JP2017190267A - Alumina particle material and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of an alumina particle material, with which a particle material can be phase-transferred to an α-phase while suppressing change of the shape.SOLUTION: A method to α-convert a particle material while mostly maintaining sphericity is disclosed. The method is completed by finding that when the speed of advance of α-conversion is equal to or larger than a specified value, the particle material is deformed and sphericity is deteriorated. For suppressing advance of α-conversion, (i) a method to lower heating temperature, and (ii) a method to use a silicon-containing compound which reduces the speed of advance of α-conversion are found to be effective. In the method to lower heating temperature (i), as it has been made apparent that α-conversion does not advance in a state of a low content of the α-phase by simply lowering the temperature, temperature is lowered after a portion of the particle material has been α-converted initially, and thereby α-conversion has advanced slowly thereafter. In the method (ii), the speed of advance of α-conversion can be suitably controlled by suitably controlling the content of the silicon-containing compound.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a highly spherical alumina particle material and a method for producing the same.

  As a mounting material such as a semiconductor sealing material, a resin composition in which a filler is dispersed in a resin is widely used. Dispersing the filler improves the physical properties of the mounting material.

  It is known that the shape of the filler is preferably closer to a true sphere from the viewpoint of fluidity, filling properties, wearability, etc. (As an example of conventional α-alumina, FIG. 3: Sumiko Random AA3, Sumitomo Chemical Co., Ltd. Company-made). Silica and alumina are commonly used as the filler, but alumina has an advantage that it has excellent thermal conductivity (Patent Document 1, etc.).

Japanese Patent Laid-Open No. 2001-019425 JP2016-028993

  By the way, although the thermal conductivity of the α phase is high as the crystal structure of alumina, it is difficult to produce a true spherical particle material made of α phase alumina (Patent Document 2, etc.). There is a VMC method (deflagration method) for producing true spherical alumina. However, since the amorphous alumina is formed in the VMC method, it is necessary to perform a phase transition to the α phase. In order to make the phase transition to the α phase, it is necessary to heat it above a certain temperature. However, the shape of the particle material changes with the phase transition, so that the true spherical shape cannot be maintained or the particle material cannot be fused. There was a problem of wearing (as a typical example, FIG. 1). In particular, when the particle diameter is small, it was impossible to improve the sphericity after the formation of α.

  The present invention has been completed in view of the above circumstances, and provides an alumina particle material manufacturing method capable of phase transition of the particle material to an α phase while suppressing a change in shape, and an alumina particle material having a high sphericity and α conversion. It is a problem to be solved.

  The method for producing an alumina particle material of the present invention that solves the above-mentioned problems is a method of aluminizing an alumina particle material having a sphericity of 0.9 or more while maintaining the sphericity substantially (as a representative example, FIG. 2). It was completed based on the knowledge that the particle material is deformed and the sphericity is lowered when the progress of the pregelatinization is above a certain level.

  As a method for suppressing the progress rate of pregelatinization, (i) a method for lowering the heating temperature and (ii) a method using a silicon-containing compound, which is a compound containing silicon, which is an element that decreases the pregelatinization rate, were found.

  In the method of lowering the heating temperature of (i), it has been clarified that if the temperature is simply lowered, α-ization does not proceed in a state where the α phase ratio is low. It became possible to carry out the progress of the subsequent alpha-gradation slowly by reducing. It has been clarified that the progress of alpha conversion is slow at the beginning, and it is possible to interrupt the alpha production in a low state, but it is understood that if the heating is continued as it is, the alpha production will progress at once. Therefore, after the progress of the α-ization was interrupted at a low rate of α-ization, the subsequent α-ization rate was successfully reduced to a controllable level by heating at a lower temperature. As the temperature after the interruption, even if the α phase does not exist, the α formation can proceed using the α phase once generated as a seed, even if the α formation hardly proceeds.

In the method (ii), it is possible to appropriately control the progress rate of pregelatinization by appropriately controlling the content of the silicon-containing compound. Moreover, since the progress rate of the α-ization can be improved by coexisting a specific nitrogen compound in addition to the silicon-containing compound, the progress of the α-ization can be appropriately controlled.
(1) The method for producing an alumina particle material of the present invention has been completed based on the above (i) knowledge. That is, the method for producing an alumina particle material according to the present invention includes a particle material whose sphericity is 0.9 or more and whose main component is alumina, and the α phase is 10% or more and 40% or less at a temperature exceeding 1200 ° C. A pretreatment step of heating, and an αization step of heating to a temperature lower than 1225 ° C. and higher than 1150 ° C. to obtain a pregelatinized alumina particle material having a sphericity of 0.9 or more. Have

By preheating at a high temperature of 1200 ° C. or more as a pretreatment step, the alumina particle material is promptly gelatinized. Here, it is defined that a small amount of the particulate material is in the α phase as the end condition of the pretreatment step. This is because the pregelatinization can be easily stopped at the initial stage. Then, pregelatinization is further advanced by heating at a temperature lower than that of the pretreatment step as the pregelatinization step. The reason why the pregelatinization progresses even at a low temperature is that the pretreatment step generates the pregelatinization and the further pregelatinization proceeds.
(2) Here, in (1), the pretreatment step is preferably a step of heating at a temperature of 1220 ° C. or higher. By setting this temperature range, the generation of the α phase can surely proceed within a controllable range.
(3) In the above-mentioned (1) and / or (2), the pregelatinization step is preferably completed at a pregelatinization rate of 90% or less. By making the progress of alpha conversion within this range, deformation of the particle material can be suppressed.
(4) The method for producing the alumina particle material of the present invention is based on the above knowledge (ii). That is, the method for producing an alumina particle material according to the present invention is based on a particle material mainly composed of alumina having a sphericity of 0.9 or more and a surface area of the particle material, and less than 6.4 μmol / m ^{2 and} less than 0 μmol / m ^2. a mixing step of mixing a silicon-containing compound having a silicon atom of more than m ² to form a mixture; and heating the mixture at a temperature of more than 1200 ° C. and not more than 1325 ° C. to produce a pregelatinized alumina particle material having a sphericity of 0.9 or more A second alpha process.

By including the silicon-containing compound in the above-described range, it is possible to control the progression rate of the α-ization to an appropriate rate, so that deformation of the particle material can be suppressed.
(5) The method for producing an alumina particle material of the present invention is based on the findings of (ii) above. That is, the method for producing an alumina particle material of the present invention may be the same as the above-mentioned silicon-containing compound, a particle material having a sphericity of 0.9 or more and mainly containing alumina, a silicon-containing compound having a silicon atom, and A second mixing step in which a nitrogen-containing compound that releases a compound having an NH bond by heating is mixed to form a mixture; and the mixture is heated to above 1200 ° C. and at most 1325 ° C. to obtain a α having a sphericity of 0.9 or more And a second alphatization step for making the alumina particle material.

By including the silicon-containing compound in the above-mentioned range, it is possible to control the progress rate of the alpha conversion to an appropriate rate, so that the deformation of the particulate material can be suppressed, and the effect of the invention disclosed in (4) can be exhibited. In addition, the addition of a nitrogen-containing compound makes it possible to precisely control the advancement rate of the pregelatinization.
(6) Here, the silicon-containing compound in the inventions of the above (4) and (5) is a polysiloxane compound in which a part of the side chain is hydrogen, silica particles having a particle size of 100 nm or less, hexamethyldisilazane It is preferable that it is one or more of these.
(7) The alumina particle material of the present invention is composed of an α-alumina particle material having a particle size of 500 μm or less and a sphericity of 0.9 or more and mainly containing α-phase alumina.

  If the alumina particle material has a large particle size, it may be possible to improve the sphericity after mechanical conversion by mechanical processing, but if the particle size is small (500 μm or less), the sphericity cannot be improved. It is. In particular, when the particle size is 50 μm or less, the feasibility of improving the sphericity by mechanical processing is not considered.

It is a SEM photograph about the sample fuse | melted by heating a spherical alumina particle. It is a SEM photograph about the sample which is not fused even if it heats true spherical alumina particles. It is a SEM photograph of commercially available alumina particles. It is a SEM photograph about the alumina particle which is not fused in Test 7 of an example. It is a SEM photograph about the alumina particle fused in Test 7 of an example.

  The alumina particle material and the production method thereof according to the present invention will be described in detail based on the following embodiments. In addition, although the manufacturing method of the alumina particle material of this embodiment is a method suitable for manufacture of the alumina particle material of this embodiment, it is not a method of manufacturing only the alumina particle material of this embodiment. For example, the particle size of the alumina particle material of the present embodiment is 500 μm or less, but the method for producing the alumina particle material of the present embodiment effectively maintains its form even when applied to a particle material having a particle size of more than 500 μm. α-ization can proceed.

  The alumina particle material of the present embodiment is a material having a high degree of alpha and a high sphericity. In addition to exhibiting high thermal conductivity when employed as a filler in a resin composition, effects such as filler filling properties, improvement in fluidity of the resin composition, and reduction in wearability due to the filler are expected.

  The manufacturing method of the alumina particle material of this embodiment is roughly classified into the two forms (i) and (ii) described above. This is a method for producing an alumina particle material having a high degree of spheroidization and a high degree of spheroidization from a particulate material made of alumina having a low degree of sphericity. Note that the two forms are not exclusive and are compatible. The alpha conversion rate of the finally produced alumina particle material is not particularly limited, but is preferably 50% or more, 60% or more, or 70% or more. In addition, according to the manufacturing method of the alumina particle material of this embodiment, the change of a form can be decreased. Even if the shape slightly changes and the particles harden, they can be easily crushed.

  A method for producing a particulate material having a high sphericity is not particularly limited. An example is the VMC method. The VMC method is a method of forming a particulate material by burning metal aluminum powder particles together with oxygen into a flame. By controlling the particle size of aluminum metal, the supply rate, the mixing ratio with oxygen, and the like, the particle size, sphericity, etc. of the generated particulate material can be controlled.

  The particle size of the particle material is not particularly limited, but the effect is particularly exerted when applied to a particle material having a small particle size. This is because, when the particle size is small, the influence of fusion is large with the formation of α, heat conduction by heating is fast, and it is difficult to control heating. In addition, if a small particle material is applied, the alumina particle material obtained by the present invention can be used for such a mounting material in a situation where the mounting material is becoming lighter and thinner. Specifically, the upper limit of the particle diameter of the particle material that is effective when applied includes 500 μm, 200 μm, 100 μm, 50 μm, 20 μm, 10 μm, 5 μm, 3 μm, 2 μm, 1 μm, and the like. This particle size can be determined by the particle size of individual particles, or by D50 or volume average particle size. Moreover, the same range can be employ | adopted as a preferable particle size of the alumina particle material of this embodiment.

The value of sphericity is preferably 0.95 or more, and more preferably 0.99 or more. The sphericity is measured and calculated from the SEM photograph. Specifically, arbitrary particles are selected from the SEM photograph, and the projected area (A) and circumference (M) of the particles are measured. Assuming a true sphere having the measured circumference (M), its radius (r) is M / 2π, and the assumed area (B) of the true sphere is π × (M / 2π) ² . The sphericity (A / B) = A × 4π / M ² is calculated from the areas A and B thus measured and calculated. The sphericity is measured for 100 particles, and the average value is adopted as the sphericity.
(First form)
The manufacturing method of the alumina particle material of this embodiment is equivalent to the above-mentioned (i), and has a pretreatment process and an alpha process. Furthermore, it can have a crushing process as needed.
-Pre-processing process A pre-processing process is a process of heating the particulate material used as a raw material at the temperature over 1200 degreeC. As the lower limit of the heating temperature, 1210 ° C., 1220 ° C., and 1225 ° C. can be adopted. Examples of the upper limit include 1275 ° C., 1260 ° C., and 1250 ° C. in view of the ease of controlling the progress of the pregelatinization.

The heating time is performed until the α phase becomes 10% or more and 40% or less. This is a range in which the entire alumina particle material is not pregelatinized (the α phase is less than 50%) and is set as a range in which the progress of the pregelatinization can be stopped by stopping heating. As the lower limit value, 15% and 20% can be adopted, and as the upper limit value, 35% and 30% can be adopted.
-Alpha process The alpha process is a process of heating at a lower temperature than the pretreatment process. Since the heating is performed at a temperature lower than that in the pretreatment step, the α-formation usually does not proceed or is slow, but since some of the particles have been α-ized by the pretreatment step, the α-phase is the starting point. As shown in FIG. Further, the upper limit is a temperature lower than 1225 ° C., and the lower limit is more than 1150 ° C. It can be estimated that the sphericity decreases when this step is performed. This step is performed in a range where the sphericity is 0.9 or more. Although it does not specifically limit as a specific method of heating, Well-known apparatuses and methods, such as a rotary kiln, are employable.

The degree of pregelatinization in this step is preferably stopped when the α phase is 90% or less, and more preferably 80% or less. The treatment time of this step is preferably determined based on the result of examination in a test in which the pregelatinization rate is preliminary.
-Crushing process Primary particle | grains may aggregate in the pregelatinization process mentioned above. In that case, it is preferable to crush by some method. Even if a crushing step is not particularly provided, it can be sufficiently expected that crushing proceeds while handling the alumina particle material. However, by adopting the crushing step, it is possible to quickly crush to a state close to primary particles. Specifically, a preferable crushing method is a method of applying a shearing force to the aggregated primary particles using a pulverizer or a mixer, and examples thereof include a method of treating with a jet mill.
(Second form)
The manufacturing method of the alumina particle material of this embodiment has a (2nd) mixing process and a 2nd alpha formation process. If necessary, the crushing step described in the first embodiment can be employed as it is. When combined with the manufacturing method of the first form, the mixing process or the second mixing process of the second form can be adopted before the alpha conversion process of the first form.
-Mixing process A mixing process is a process of mixing a silicon containing compound with respect to particulate material. The mixing method is not particularly limited, but it is preferable to mix so that the particle material is coated with the silicon-containing compound. That is, it is preferable that a silicon-containing compound is disposed at the interface of the particle material. If a material in which a silicon-containing compound is disposed at the interface of the particle material can be formed, there is a possibility that a composition exhibiting favorable pregelatinization behavior when subjected to the pregelatinization step described below without depending on mixing may be obtained. (The second mixing step is the same).

  A silicon-containing compound is a compound containing a silicon atom in the composition. Examples thereof include polysiloxane and silica. The polysiloxane is preferably partially hydrogenated in the side chain. Silica preferably has a small particle size. For example, the particle size is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less. The method for producing silica having a small particle size is not particularly limited, and can be produced by a sol-gel method, a VMC method, or the like. Silica having a small particle size may be used for the mixing step in a state of being dispersed in water called colloidal silica or may be used in a dry state. When used in a dry state, it is preferably used in a state where it can be separated into primary particles. It is preferable to employ silica particles that have been subjected to a surface treatment described later because the amount of impurities can be reduced by washing as necessary.

The silicon-containing compound is preferably mixed so as to have silicon atoms of less than 6.4 μmol / m ^{2 and} more than 0 μmol / m ² on the basis of the surface area of the particulate material. 5 [mu] mol ^{/ m} 2 as the upper limit, 4μmol ^{/ m} 2, can be exemplified about ^{3μmol / m 2, 0.5μmol / m} 2 as a lower limit, 1μmol ^/ m 2, about 1.5μmol / ^{m 2} can be exemplified. By making it within this range, the progress of the alpha conversion is suppressed and the control becomes easy.
-2nd mixing process It can replace with a mixing process and can also employ | adopt a 2nd mixing process. In the second mixing step, in addition to the silicon-containing compound, a nitrogen-containing compound that releases a compound having an NH bond by heating is also mixed. Although it does not specifically limit as a nitrogen-containing compound, Compounds, such as hexamethyldisilazane (HMDS) which has NH bond in the molecule | numerator of a silicon-containing compound, can also be employ | adopted individually or in combination.

When a nitrogen-containing compound is contained, the silicon-containing compound exerts an effect of accelerating the α-conversion as opposed to suppressing the progress of the α-ization. For this reason, the appropriate amount for mixing the silicon-containing compound also increases according to the amount of the nitrogen-containing compound added, so that it is difficult to apply the appropriate value shown in the above mixing step as it is. According to the findings by HMDS, in the range where the amount of HMDS added is small, the effect of suppressing the progress of pregelatinization is the main effect, and the effect of promoting pregelatinization is not noticeable. When the amount of HMDS added is increased, the promotion effect is the main effect rather than the progress inhibition effect of the pregelatinization. 34.3μmol / ^{m 2} near (30~40μmol / ^{m 2} or so) and 85.7μmol / ^{m 2} near (75~95μmol / ^{m 2} or so) in the preferred amount as the amount of silicon atoms as an additive amount of the order HMDS Is recognized.
-2nd gelatinization process The obtained mixture is heated above 1200 degreeC at 1325 degrees C or less, and it is set as the alpha alumina particle material whose sphericity is 0.9 or more. It can be estimated that the sphericity decreases when this step is performed. Examples of the lower limit of the heating temperature include 1220 ° C, 1225 ° C, and 1250 ° C. Although it does not specifically limit as a specific method of heating, Well-known methods, such as a rotary kiln, are employable.
(Example of surface treatment when silica particles are employed as the silicon-containing compound: production of surface-treated silica particles)
A method for producing the surface-treated silica particles is exemplified below. Surface-treated silica particles (surface-treated silica particles) are represented by the functional group represented by the formula (1): -OSiX ¹ X ² X ³ and the formula (2): -OSiY ¹ Y ² Y ^3. Are attached to the surface. Hereinafter, the functional group represented by the formula (1) is referred to as a first functional group, and the functional group represented by the formula (2) is referred to as a second functional group.

X ¹ in the first functional group is a phenyl group, vinyl group, epoxy group, methacryl group, amino group, ureido group, mercapto group, isocyanate group, or acrylic group. X ² and X ³ are —OSiR ³ or —OSiY ⁴ Y ⁵ Y ⁶ , respectively. Y ⁴ is R. Y ⁵ and Y ⁶ are each R or —OSiR 3.

Y ¹ in the second functional group is R. Y ² and Y ³ are each —OSiR ³ or —OSiY ⁴ Y ⁵ Y ⁶ .

  The more -OSiR3 contained in the first functional group and the second functional group, the more R on the surface of the surface-treated silica particles. The more R (alkyl group having 1 to 3 carbon atoms) contained in the first functional group and the second functional group, the less the surface-treated silica particles are aggregated.

Regarding the first functional group, when X ² and X ³ are each —OSiR ³ , the number of R is minimized. Further, ^{X 2} and ^{X 3} are each a -OSiY ⁴ Y ⁵ Y ^{6, and,} if Y 5, ^{Y 6} is -OSiR3 respectively, the number of R is maximized.

Regarding the second functional group, when Y ² and Y ³ are each —OSiR ³ , the number of R is minimized. Further, ^{Y 2} and ^{Y 3} are -OSiY ⁴ Y ⁵ Y ^6, respectively, ^and, in the case of Y 5, ^{Y 6} Gazorezore -OSiR3, the number of R is maximized.

The number of X ¹ contained in the first functional group, the number of R contained in the first functional group, and the number of R contained in the second functional group are the abundance ratio of R and X ¹ , silica What is necessary is just to set suitably according to the particle size and use of particle | grains.

^{Incidentally, X 2, X 3, Y} 2, Y 3, Y 5, and any of ^{Y 6, X} 2 of the adjacent ^{functionality, X 3, Y 2, Y} 3, Y 5, and any ^{Y 6} You may combine with heel -O-. For example, any one of the first functional group X ² , X ³ , Y ⁵ , and Y ⁶ is the first functional group adjacent to the first functional group X ² , X ³ , Y ⁵ , and It may be bonded to any of Y ⁶ by —O—. Similarly, any of Y ² , Y ³ , Y ⁵ , and Y ⁶ of the second functional group is replaced with Y ² , Y ³ , Y ⁵ , Y ² of the second functional group adjacent to the second functional group. And Y ⁶ may be bonded to each other by —O—. Furthermore, any one of the first functional groups X ² , X ³ , Y ⁵ , and Y ⁶ is the second functional group adjacent to the first functional group, Y ² , Y ³ , Y ⁵ , And Y ⁶ may be bonded to each other by —O—.

In the surface-treated silica particles, if the abundance ratio of the first functional group to the second functional group is 1:12 to 1:60, X ¹ and R are balanced on the surface of the surface-treated silica particles. It exists well. For this reason, the surface-treated silica particles having an abundance ratio of the first functional group to the second functional group of 1:12 to 1:60 are particularly excellent in the affinity for the resin and the aggregation suppressing effect. Moreover, X ¹ is as long as 0.5 to 2.5 per unit surface area of the surface-treated silica particles (nm ^2), surface-treated first functional groups of sufficient number to the surface of the silica particles are bonded There are also a sufficient number of R derived from the first functional group and the second functional group. Therefore, also in this case, the affinity for the resin and the effect of suppressing aggregation of the silica particles are sufficiently exhibited.

In any case, R per unit surface area (nm ² ) of the surface-treated silica particles is preferably 1 to 10. In this case, the balance between the number of X ¹ present on the surface of the surface-treated silica particles and the number of R is improved, and both the affinity for the resin and the aggregation suppressing effect of the surface-treated silica particles are well balanced. Demonstrated.

In the surface-treated silica particles, it is preferable that all of the hydroxyl groups present on the surface of the silica particles are substituted with the first functional group or the second functional group. When the sum of the first functional group and the second functional group is 2.0 or more per unit surface area (nm ² ) of the surface-treated silica particles, the surface-treated silica particles have the surface of the silica particles It can be said that almost all of the existing hydroxyl groups are substituted with the first functional group or the second functional group.

The surface-treated silica particles have R on the surface. This can be confirmed by an infrared absorption spectrum. Specifically, when the infrared absorption spectrum of the surface-treated silica particles is measured by a solid diffuse reflection method, there is a maximum absorption of C—H stretching vibration at 2962 ± 2 cm ⁻¹ . For this reason, it can be confirmed by the infrared absorption spectrum whether it is a surface-treated silica particle.

  Further, as described above, the surface-treated silica particles hardly aggregate. Therefore, the surface-treated silica particles can be applied to silica particles having a small particle size. For example, the surface-treated silica particles can have an average particle size of about 3 nm to 5000 nm. It is preferable to apply to silica particles having an average particle diameter of 3 to 200 nm.

  The surface-treated silica particles can be dispersed again by ultrasonic treatment even if they are slightly aggregated. Specifically, the surface-treated silica particles can be substantially dispersed into primary particles by irradiating the surface-treated silica particles dispersed in methyl ethyl ketone with ultrasonic waves having an oscillation frequency of 39 kHz and an output of 500 W. The ultrasonic irradiation time at this time may be 10 minutes or less. Whether or not the surface-treated silica particles are dispersed into primary particles can be confirmed by measuring the particle size distribution. Specifically, if the silica particle methyl ethyl ketone dispersion material is measured with a particle size distribution measuring device such as a microtrack device, and if there is a particle size distribution of the silica particles, it can be said that the surface-treated silica particles are dispersed to primary particles.

  Since the surface-treated silica particles hardly aggregate, they can be provided as silica particles that are not dispersed in a liquid medium such as water or alcohol. In this case, since no liquid medium is brought in, it is preferably used as a filler for a resin material.

  The surface-treated silica particles preferably have a bulk density of 450 g / L or less. The measurement of the bulk density in this specification is performed using the Tsutsui RIKEN KIKAI CO., LTD .: electromagnetic vibration type | mold density measuring device (MVD-86 type | mold). Specifically, after the sample to be measured is put into the upper 500 μm sieve as the sample tank, the sample is dispersed through the two upper and lower 500 μm sieves under electromagnetic acceleration conditions, and dropped into a 100 mL sample container. The mass was measured, and the bulk density was calculated from the mass and volume. In order to prevent a decrease in bulk density due to its own weight, measurement should be performed within 1 hour after dropping.

  Preferable upper limit is 400 g / L, 350 g / L, 300 g / L, 250 g / L. A preferred lower limit is 100 g / L. By setting the bulk density to a value below these upper limits, primary particles can be separated more reliably. Moreover, when the bulk density is set to a value higher than these lower limits, the bulk is small and the handling becomes easy.

As a method of obtaining surface-treated silica particles by subjecting the silica particles to surface treatment, there is a step of treating the silica particles with a silane coupling agent and an organosilazane (surface treatment step) in a liquid medium containing water. The silane coupling agent has three alkoxy groups and a phenyl group, a vinyl group, an epoxy group, a methacryl group, an amino group, a ureido group, a mercapto group, an isocyanate group, or an acrylic group (that is, X ¹ described above).

By performing the surface treatment with the silane coupling agent, the hydroxyl group present on the surface of the silica particles is substituted with a functional group derived from the silane coupling agent. The functional group derived from the silane coupling agent is represented by the formula (3); —OSiX ¹ X ⁴ X ⁵ . The functional group represented by the formula (3) is referred to as a third functional group. X ¹ in the third functional group is the same as X ¹ in the functional group represented by the formula (1). X ⁴ and X ⁵ are each an alkoxy group. By surface-treating with organosilazane, the third functional group X ⁴ and X ⁵ are derived from organosilazane —OSiY ¹ Y ² Y ³ (the functional group represented by the formula (2), the second functional group ). When all of the hydroxyl groups present on the surface of the silica particles are not substituted with the third functional group, the hydroxyl groups remaining on the surface of the silica particles are substituted with the second functional group. Therefore, on the surface of the surface-treated silica particles, a functional group represented by the formula (1): —OSiX ¹ X ² X ³ (that is, the first functional group) and a formula (2): —OSiY ¹ The functional group represented by Y ² Y ³ is bonded to the functional group (that is, the second functional group). In addition, since the molar ratio of the silane coupling agent to the organosilazane is silane coupling agent: organosilazane = 1: 2 to 1:10, the first functional group and the first functional group in the obtained surface-treated silica particles The abundance ratio with the functional group of 2 is theoretically from 1:12 to 1:60.

In the surface treatment step, the silica particles may be simultaneously surface treated with a silane coupling agent and an organosilazane. Alternatively, the silica particles may first be surface treated with a silane coupling agent and then surface treated with organosilazane. Alternatively, the silica particles may be first surface treated with organosilazane, then surface treated with a silane coupling agent, and then surface treated with organosilazane. In any case, the amount of organosilazane may be adjusted so that all the hydroxyl groups present on the surface of the silica particles are not substituted with the second functional group. The hydroxyl groups present on the surface of the silica particles may all be substituted with the third functional group, or only a part may be substituted with the third functional group, and the other part may be substituted with the second functional group. It may be replaced. All of X ⁴ and X ⁵ contained in the third functional group may be substituted with the second functional group.

A part of organosilazane may be replaced with the second silane coupling agent. As the second silane coupling agent, one having three alkoxy groups and one alkyl group can be used. In this case, X ⁴ and X ⁵ contained in the third functional group are substituted with the fourth functional group derived from the second silane coupling agent. The fourth functional group has the formula (4); - represented by OSiY ¹ X ⁶ X ^7. Y ¹ is the same R as ^{Y 1} in the second functional ^{group, X 6,} X ⁷ is an alkoxy group or a hydroxyl group, respectively. X ⁶ and X ⁷ contained in the fourth functional group are substituted with the second functional group derived from organosilazane, or are substituted with another fourth functional group. In this case, the amount of R present on the surface of the silica particles can be further increased. When a part of the organosilazane is replaced with the second silane coupling agent, it is necessary to surface-treat with the organosilazane again after the surface treatment with the second silane coupling agent. This is because X ⁶ and X ⁷ contained in the fourth functional group are finally substituted with the second functional group derived from organosilazane.

When a part of the organosilazane is replaced with the second silane coupling agent, X ⁴ and X ⁵ contained in the first functional group described above are substituted with the second functional group derived from the organosilazane, Substitution with a fourth functional group derived from the second silane coupling agent. When X ⁴ and X ⁵ are substituted with the fourth functional group, X ⁶ and X ⁷ contained in the fourth functional group are substituted with the second functional group or another fourth functional group. Is replaced by If X ^6, X ⁷ contained in the fourth functional group has been replaced by another fourth functional group, X ^6, X ⁷ contained in the fourth functional groups is substituted with the second functional group The For this reason, the second silane coupling agent is an organosilazane set when the surface treatment is performed only with the first coupling agent and the organosilazane (when the organosilazane is not replaced with the second silane coupling agent). A maximum of 5a / 3 mol can be substituted for the amount (a) mol. The amount of organosilazane required in this case is 8a / 3 mol.

  The alkoxy groups of the silane coupling agent and the second silane coupling agent are not particularly limited, but those having a relatively small carbon number are preferred, and those having 1 to 12 carbon atoms are preferred. Considering the hydrolyzability of the alkoxy group, the alkoxy group is more preferably any one of a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

  Specific examples of silane coupling agents include phenyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-glycidoxypropyltrimethoxysilane. 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-phenyl-3 -Aminopropyltrimethoxysilane.

  Any organosilazane may be used as long as it can replace the hydroxyl group present on the surface of the silica particles and the alkoxy group derived from the silane coupling agent with the second functional group described above. preferable. Specific examples include tetramethyldisilazane, hexamethyldisilazane, pentamethyldisilazane, and the like.

  Examples of the second silane coupling agent include methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, and hexyltriethoxysilane.

  In the surface treatment step, a polymerization inhibitor may be added in order to suppress polymerization of the silane coupling agent or polymerization of the second silane coupling agent. As the polymerization inhibitor, common ones such as 3,5-dibutyl-4-hydroxytoluene (BHT) and p-methoxyphenol (methoquinone) can be used.

  The surface treatment method for silica particles may include a solidification step after the surface treatment step. The solidification step is a step of precipitating the surface-treated silica particles with a mineral acid and washing and drying the precipitate with water to obtain a solid of silica particles. As described above, since general silica particles are very likely to aggregate, it is very difficult to disperse once solidified silica particles. However, since silica particles are difficult to aggregate, they are difficult to aggregate even when solidified, and are easily redispersed even when aggregated. In addition, as mentioned above, the silica particle used for uses, such as an electronic component, can be easily manufactured by wash | cleaning a silica particle with water. In the washing step, washing is preferably repeated until the electric conductivity of silica particle extraction water (specifically, water in which silica particles are immersed at 121 ° C. for 24 hours) is 50 μS / cm or less.

  Examples of the mineral acid used in the solidification step include hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and hydrochloric acid is particularly desirable. The mineral acid may be used as it is, but is preferably used as a mineral acid aqueous solution. The concentration of the mineral acid in the aqueous mineral acid solution is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. The amount of the mineral acid aqueous solution can be about 6 to 12 times based on the mass of the silica particles to be cleaned.

  The cleaning with the mineral acid aqueous solution can be performed a plurality of times. The washing with the mineral acid aqueous solution is preferably performed after the surface-treated silica particles are immersed in the mineral acid aqueous solution and then stirred. Further, it can be left in the immersed state for 1 to 24 hours, and further for about 72 hours. When it is allowed to stand, stirring can be continued or not stirred. When washing in the mineral acid-containing liquid, it can be heated to room temperature or higher.

  Thereafter, the surface-treated silica particles washed and suspended are collected by filtration and then washed with water. It is desirable that the water used does not contain ions such as alkali metals (for example, 1 ppm or less on a mass basis). For example, ion exchange water, distilled water, pure water and the like. Washing with water is the same as washing with mineral acid aqueous solution. The surface-treated silica particles can be dispersed and suspended, and then filtered, or the filtered surface-treated silica particles can pass through water continuously. This is also possible. The end of washing with water may be determined by the electric conductivity of the extracted water described above, or may be the time when the alkali metal concentration in the waste water after washing the surface-treated silica particles becomes 1 ppm or less. And it is good also as the time of the alkali metal concentration of extraction water becoming 5 ppm or less. When washing with water, it can be heated to a room temperature or higher.

  The surface-treated silica particles can be dried by a conventional method. For example, heating or leaving under reduced pressure (vacuum).

  As a method of dehydrating the surface-treated silica particles other than drying, a mixed material that can be dissolved in the water-based organic solvent after adding a water-based organic solvent having a boiling point higher than water to the water-treated surface-treated silica particles Can be used to remove water. Examples of aqueous organic solvents include propylene glycol monomethyl ether (propylene glycol-1-methyl ether, boiling point of about 119 ° C .; propylene glycol-2-methyl ether, boiling point of about 130 ° C.), butanol (boiling point of 117.7 ° C.), N-methyl- Examples include 2-pyrrolidone (boiling point of about 204 ° C.) and γ-butyrolactone (boiling point of about 204 ° C.).

(Test 1: Alphaization by heating to particulate material: Part 1)
The time dependence of the alpha conversion rate when the particulate material made of alumina with D50 of 0.58 μm and an initial alpha conversion ratio of 2% was heated at various temperatures was examined. At the same time, the form of the heated product obtained was observed with an SEM to evaluate the degree of fusion.

  The heating temperatures were 1225 ° C., 1250 ° C., 1275 ° C., 1300 ° C., and 1325 ° C. The heating time was 3 minutes, 5 minutes, 10 minutes, and 20 minutes. The results are shown in Table 1. The measured D50 was measured on a sample that had been baked under a certain condition in an automatic mortar. A larger D50 is considered to have a greater degree of fusion. Here, an SEM photograph of the sample treated at 1325 ° C. for 3 minutes is shown in FIG.

As is apparent from the table, it was found that after the alpha conversion rate progressed to around 20%, the alpha conversion rate progressed to around 90% in a short time, and the degree of fusion also advanced. It was found that the change in the pregelatinization rate was abrupt and it was difficult to stop in the middle of the state (conditions that fall between 30% and 80% of the pregelatinization degree could not be found).
(Test 2: Alpha conversion by heating to particulate material: Part 2)
The time dependence of the alpha conversion rate when the particulate material made of alumina with D50 of 8.8 μm and the original alpha conversion ratio of 19% was heated at various temperatures was examined. At the same time, the form of the heated product obtained was observed with an SEM to evaluate the degree of fusion.

  The heating temperatures were 1225 ° C., 1250 ° C., 1275 ° C., 1300 ° C., and 1325 ° C. The heating time was 3 minutes, 5 minutes, and 10 minutes. The results are shown in Table 2.

As can be seen from the table, the degree of pregelatinization, which was about 19%, exceeded 90% in 3 minutes to 5 minutes, and it was found that the progress of the degree of pregelatinization was rapid as in the test of “Part 1”. . Note that the degree of fusion was weak under these conditions. This was presumed to be due to the fact that, under this condition, the initial D50 was 8.8 μm, which was larger than “Part 1” D50, and the particle diameters were uniform, so there was little contact between the particles. In addition, although the particle | grains with a small particle diameter existed on the surface from the beginning, the small particle | grain was fuse | melted to the large particle | grain by heating. It should be noted that the degree of pregelatinization changed rapidly from 19% to 90% or more (in a few minutes), and since the change was faster than in the “No. 1” test, It was speculated that the phase transition proceeded rapidly starting from the α phase.
(Test 3: Examination of multi-step heating temperature for particulate material)
In Test 1, it was found that when heated at 1225 ° C. for 10 minutes, the degree of pregelatinization was 25%. The progress of pregelatinization when the sample was heated at various temperatures as a raw material was examined.

  A particle material made of alumina having a D50 of 0.58 μm and an initial alpha conversion rate of 2% was heat-treated at 1225 ° C. for 10 minutes. As a result, the α degree was 33% and D50 was 2.4. The sample was heated at 1100 ° C., 1150 ° C., and 1200 ° C. The heating time was 5 minutes, 10 minutes, 15 minutes, and 20 minutes, and the time dependence of the pregelatinization rate was examined. At the same time, the form of the heated product obtained was observed with an SEM to evaluate the degree of fusion. The results are shown in Table 3. Here, an SEM photograph of the sample treated at 1200 ° C. for 20 minutes is shown in FIG.

As is apparent from the table, the fusion which causes a problem in heating at 1200 ° C. or less did not proceed, and D50 did not become too large. In the heating at 1200 ° C., the degree of alpha conversion increased linearly with the passage of time, and the control of the degree of alpha alpha became easy. In addition, a slight increase in the degree of α was observed even at 1150 ° C., which could be expected to be used for controlling the degree of α. Under these conditions, the tendency of change in the degree of alpha conversion was not known when heated at 1100 ° C. In addition, when the same sample was heated at 1125 degreeC, it progressed to the alpha degree of 86% in 10 minutes, and it turned out that D50 is also 16.0 micrometers and a fusion degree becomes strong and the grade of a fusion | melting becomes high.
(Test 4: Examination of silicon-containing compound: polysiloxane in which some side chains are hydrogen-substituted)
Various types of polysiloxanes (manufactured by Shin-Etsu Chemical Co., Ltd., KF9901) in which some side chains are hydrogenated as a silicon-containing compound with respect to a particle material made of alumina having a D50 of 0.58 μm and an initial alpha conversion rate of 2% The time dependency of the alpha conversion rate when the mixture obtained by mixing at a ratio (mass% based on the mass of the particulate material: molar amount based on the surface area of the particulate material) was heated at 1275 ° C. was examined. At the same time, the form of the heated product obtained was observed with an SEM to evaluate the degree of fusion. The heating time was 3 minutes, 5 minutes, and 10 minutes. The results are shown in Table 4.

As is apparent from the table, it was found that the advancement rate of the pregelatinization can be suppressed by adding the silicon-containing compound. Moreover, it turned out that the progress rate of pregelatinization also falls with the increase in addition amount. In particular, it was found that the progress of the pregelatinization of the sample added with 0.1% or 0.2% is excellent in controllability.
(Test 5: Examination of silicon-containing compound: silica)
Various silica particles (volume average particle diameter 10 nm, phenyl group introduced on the surface, manufactured by Admatechs) as a silicon-containing compound with respect to the particle material made of alumina with D50 of 0.58 μm and an initial alpha conversion rate of 2% The time dependency of the alpha conversion rate when the mixture obtained by mixing at a ratio (mass% based on the mass of the particulate material: molar amount based on the surface area of the particulate material) was heated at 1275 ° C. was examined. At the same time, the form of the heated product obtained was observed with an SEM to evaluate the degree of fusion. The heating time was 3 minutes, 5 minutes, and 10 minutes. The results are shown in Table 5.

As is apparent from the table, it was found that the advancement rate of the pregelatinization can be suppressed by adding the silicon-containing compound. Moreover, it turned out that the progress rate of pregelatinization also falls with the increase in addition amount. In particular, it has been found that the progress of the pregelatinization of the sample added in the range of 0.1% to 0.5% is excellent in controllability.
(Test 6: Examination of silicon-containing compound and nitrogen-containing compound: HMDS)
Various ratios of HMDS as a silicon-containing compound and a nitrogen-containing compound with respect to a particle material made of alumina with D50 of 0.58 μm and an initial alpha conversion rate of 2% (mass% based on the mass of the particle material: particle material The time dependence of the pregelatinization rate when heated at 1275 ° C. was examined for a mixture obtained by mixing at a molar amount based on the surface area of the slag. At the same time, the form of the heated product obtained was observed with an SEM to evaluate the degree of fusion. The heating time was 3 minutes, 5 minutes, and 10 minutes. The results are shown in Table 6.

As is apparent from the table, it has been found that the addition amount and the advancement rate of the pregelatinization are not simply correlated with each other by adding a nitrogen-containing compound in addition to the silicon-containing compound. Specifically, it was found that, after the treatment with HDMS and the aging treatment at 60 ° C. for 12 hours, the addition rate of 5.0% is excellent in controllability of the progress of the α-formation. It was found that for those not subjected to aging treatment, the addition of 2.0% is excellent in controllability of the progression rate of pregelatinization. That is, it was considered that addition of 2.0% (without aging) and 5.0% (with aging: ammonia generation) exhibited the same effect of suppressing α-formation depending on the presence or absence of aging. In addition, HMDS is hydrolyzed by aging at 60 ° C. for 12 hours to produce ammonia, but since the ammonia remains, the effect of promoting α-ization due to ammonia is exerted, so that the test is different between different concentrations. It is considered that an inhibitory effect was observed. It was speculated that the promotion effect of ammonia-induced amination was related to the formation of aluminum nitride with a crystal structure similar to that of the α-phase of alumina.
(Test 7)
The sphericity of the alumina particle material obtained for Tests 1-6 was measured. The sphericity was measured by the method described above. FIG. 4 shows an example of a sample in which fusion has progressed, and FIG. 5 shows an example of a sample in which fusion has not progressed. 4 and 5 depict a line surrounding the periphery of the particle, and the sphericity is calculated by the above formula using the length of the line and the area of the particle. The sample of FIG. 4 has a sphericity of 0.67, and the sample of FIG. 5 has a sphericity of 0.96. In Tests 1 to 6, it was judged that the degree of fusion was “weak”, and all the samples had a sphericity of 0.9 or more.
(Test 8)
In the tests 1 to 7 described above, the state before and after crushing with a jet mill was examined for the case where the degree of fusion was “strong” and “weak”. The “weak” particles were able to be in a state close to primary particles while maintaining the sphericity after crushing. For example, when KF9901 was treated with 0.1% (Si content: 2.1 μmol / m ² ) and heated at 1275 ° C. for 10 minutes under the same conditions as in Test 4, D50 was found immediately after heating. When the true specific gravity was 8.8 μm and the true specific gravity was 3.7 g / mL, after pulverizing with a jet mill, the D50 was 0.6, the true specific gravity was 3.9, and the particle material was 0.58 μm. It was possible to crush to the same level as. Further, it was found that the sphericity after pulverization was a value that was almost the same as that of the raw material particle material, and the α-degree was as high as 83%.

  Other samples with a low degree of fusion were also able to be crushed to a particle size and sphericity comparable to that of the raw material. Some samples with a fusion strength of “strong” can be crushed, but some of the energy required for crushing is higher than that of “weak”, and some samples cannot be crushed. It was also found that the sphericity was significantly lower than that of the raw material particle material although the degree of alpha conversion could be increased even if the material could be crushed.

Claims (8)

A particle material having a sphericity of 0.9 or more and mainly composed of alumina;
A pretreatment step of heating until the α phase becomes 10% or more and 40% or less at a temperature exceeding 1200 ° C .;
An alphatization step of heating to a temperature lower than 1225 ° C and greater than 1150 ° C to a pregelatinized alumina particle material having a sphericity of 0.9 or more,
The manufacturing method of the alumina particle material which has this.   The method for producing an alumina particle material according to claim 1, wherein the pretreatment step is a step of heating at a temperature of 1220 ° C or higher.   The method for producing an alumina particle material according to claim 1 or 2, wherein the pregelatinization step is completed at a pregelatinization rate of 90% or less. A particle material having a sphericity of 0.9 or more and mainly composed of alumina, and a silicon-containing compound having a silicon atom of less than 6.4 μmol / m ^{2 and} more than 0 μmol / m ^{2 based on} the surface area of the particle material A mixing step of mixing into a mixture;
A second α-izing step in which the mixture is heated above 1200 ° C. and below 1325 ° C. to obtain an α-aluminized alumina particle material having a sphericity of 0.9 or more;
The manufacturing method of the alumina particle material which has this. Particulate material having a sphericity of 0.9 or more and mainly composed of alumina, a silicon-containing compound having a silicon atom, and a nitrogen-containing compound that releases the compound that may be the same as the silicon-containing compound and that has an NH bond by heating A second mixing step of mixing
A second α-izing step in which the mixture is heated above 1200 ° C. and below 1325 ° C. to obtain an α-aluminized alumina particle material having a sphericity of 0.9 or more;
The manufacturing method of the alumina particle material which has this.   The alumina particles according to claim 4 or 5, wherein the silicon-containing compound is one or more of a polysiloxane compound in which a part of a side chain is hydrogen, a silica particle having a particle size of 100 nm or less, and hexamethyldisilazane. Material manufacturing method.   An alumina particle material having a particle size of 500 μm or less and a sphericity of 0.9 or more and comprising an α-alumina particle material mainly composed of α-phase alumina.   The alumina particle material according to claim 7, wherein the particle size is 50 μm or less.