JP3869241B2 - Ceramic powder - Google Patents

Description

【００４３】
（４）樹脂複合材料の評価
次に、前記実施例４で製造した２次粒子からなるシリカ造粒粉末と、セラミックス１次粒子であるシリカ微粒子の粉末とを用いて、ＰＥＴ樹脂からなる複合材料を製造した。そして、その試験片について、曲げ強度、曲げ弾性率、Ｔｇ（ガラス転移点）、吸湿性（吸水率）、アイゾット衝撃値および線膨張率を測定した結果を表２に示す。
【００４４】
なお、上記試験片は、次のようにして製造した。先ず、セラミックス粉末（シリカ造粒粉末またはシリカ微粒子）５０部とＰＥＴペレット（帝人製、ＴＲ４５５０ＢＨＫ）５０部とをミキサーで予備混合し、二軸押出機を用いて溶融混錬してペレット化した。そのペレットを射出成形機により成形して、上記試験片を製造した。
【００４５】
【表２】

【００４６】
以上の実施例から解るように、本発明に係るセラミックス粉末を用いると、２次粒子の分散性や流動性が良好であり、また、得られたセラミックス分散樹脂材の特性も良好であった。
【００４７】
【発明の効果】
本発明のセラミックス粉末によれば、マトリックス材中における分散性と、製造時の流動性との両立を図ることができる。
【図面の簡単な説明】
【図１】１次粒子占有体積率と２次粒子の分散性および流動性との相関関係を示す分散図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ceramic powder that is dispersed and filled in a matrix material.
[0002]
[Prior art]
Various composite materials are used from the viewpoint of achieving multi-functionality of materials. For example, a resin composite material in which ceramic particles are dispersed and filled in a matrix resin is used for the purpose of improving the strength, rigidity, thermal conductivity, heat resistance and the like of the resin. As a specific example, a semiconductor chip sealing material in which ceramic particles such as silicon oxide (silica) or silicon carbide are dispersed and filled in an epoxy resin or the like is used. By dispersing the ceramic particles, the heat dissipation (thermal conductivity), strength, etc. of the sealing material can be improved.
[0003]
By the way, spherical oxide fine particles (ceramic fine particles) are used as such a ceramic dispersion material. The oxide fine particles are produced, for example, by a VMC method (Vaporated Metal Combination Method). Briefly explaining this method, a chemical flame is formed by a burner in an oxygen atmosphere, and the raw material powder (metal powder, etc.) of the target oxide fine particles is introduced into the chemical flame to such an extent that a dust cloud is formed. To do. Then, fine oxide particles are obtained by deflagration, melting, and scattering. The fine oxide particles obtained by this method have a substantially spherical shape and a sharp particle size distribution (that is, the particle size is substantially constant). When these oxide fine particles are used as a resin filler, various functions of the resin material such as wear resistance, dimensional stability, thermal conductivity, and heat resistance can be improved. Spherical silica fine particles, which are a kind of oxide fine particles, are actually used for the semiconductor chip sealing material.
[0004]
Since the oxide fine particles obtained by the VMC method are generated in a dry state, there are few surface adsorbed water, surface hydroxyl groups and the like, and the aggregation of the particles hardly occurs. Therefore, the particles are very excellent from the viewpoint of being dispersed in the resin. However, the fine powder composed of the oxide fine particles is easily scattered. In addition, since the bulk density is large, when it is put into a hopper or the like, it becomes difficult to discharge due to internal bridging and compression. That is, the powder in the form of fine oxide particles is not easy to handle, and injection molding or the like cannot be performed efficiently.
Thus, for example, Japanese Patent Application Laid-Open No. Sho 62-96311-96313 discloses that the oxide fine particles are granulated to form secondary particles to improve the handleability of the used powder. According to those publications, silica fine particles (primary particles), which are oxide fine particles, are slurried with water, spray-dried by a spray dryer method, and granulated to improve the handleability of the oxide particles.
[0005]
[Problems to be solved by the invention]
However, when granulation is performed using water as a binder, the hydroxyl groups are strongly bonded to each other on the surface of the oxide fine particles, and strongly aggregated secondary particles are generated. As a result, even if the secondary particles and the resin are kneaded, the secondary particles are hardly decomposed into the original oxide fine particles in the resin. That is, the dispersibility in the resin is poor. Poor dispersibility may cause problems such as resin strength reduction, cracking, and surface roughness deterioration.
In addition to the granulation method disclosed in the above publication, there are a rolling granulation method and an agitation granulation method, but all use water as a binder, and the dispersibility is similarly low.
[0006]
On the other hand, if a non-aqueous binder such as an organic solvent or paraffin wax is used as the binder, the secondary particles become porous and the dispersibility can be eliminated. However, since the conventional secondary particles are not preferable in terms of fluidity, the handling of ceramic powder has not been improved in the end.
As described above, there has never been a secondary particle capable of achieving both the dispersibility of ceramic primary particles constituting the ceramic powder and the handling properties such as fluidity in a high dimension.
This invention is made | formed in view of such a situation, and provides ceramic powder which consists of the granulated secondary particle which can make the dispersibility and fluidity | liquidity of ceramic primary particle compatible in high dimension. Objective.
[0007]
[Means for Solving the Problems]
Therefore, the present inventor has eagerly studied to solve this problem, and as a result of repeated trial and error, when the volume ratio of the primary ceramic particles in the granulated secondary particles is within a predetermined range, the primary ceramics. The inventors have investigated that particle dispersibility and fluidity can be achieved at a high level, and have completed the present invention.
That is, the ceramic powder of the present invention is a ceramic powder composed of secondary particles obtained by granulating primary ceramic particles having a particle size of 0.01 to 10 μm, and the secondary particles have an overall volume ratio of 100%. Ri said primary particle volume ratio is the volume ratio of ceramic primary particles 50 to 65% der upon, the ceramic primary particles are characterized Rukoto such silica particles.
[0008]
According to the ceramic powder of the present invention, the dispersibility and fluidity of the ceramic primary particles can be made compatible, but the reason is not necessarily clear. The current situation is considered as follows.
That is, by setting the primary particle occupation volume ratio to 50 to 65%, the aggregated ceramic primary particles are moderately easily decomposed, and it is considered that both the fluidity and the dispersibility can be achieved. Here, assuming that the ceramic primary particles are isometric spheres, the occupied volume ratio in the closest packed state is about 74%. This seems to be close to the occupied volume ratio of the secondary particles granulated with water as a binder as described above.
[0009]
It can be said that the secondary particles according to the present invention are in a state where the occupied volume ratio is lower than that in the close-packed state and appropriate gaps exist between the ceramic primary particles. That is, it is considered that the dispersibility and fluidity are ensured because the ceramic primary particles are agglomerated with some gaps remaining.
When the primary particle occupation volume ratio is less than 50%, void portions increase in the secondary particles and fluidity is lowered, which is not preferable. On the other hand, if it exceeds 65%, the dispersibility of the primary particles is lowered, which is not preferable. From these viewpoints, the primary particle occupation volume ratio is more preferably 55 to 60%.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to embodiments.
(1) Ceramic primary particles Ceramic primary particles are made of ceramic fine particles having a particle size of 0.01 to 10 μm. In addition to the fine particles produced by the VMC method described above, fine particles produced by other atomizing methods may be used. Moreover, it is not limited to metal oxide fine particles such as alumina, but may be oxide fine particles such as silica, and further may be fine particles such as SiC.
[0011]
The finer the ceramic primary particles, the better the reinforcing effect and the appearance such as surface gloss when dispersed in a resin or the like, but too fine particles are difficult to manufacture and handle. Then, although the particle size of the ceramic primary particle was 0.01-10 micrometers, it is more preferable in it being 0.05-1 micrometer.
The sphericity of the ceramic primary particles can be compared using, for example, an aspect ratio. If the aspect ratio is 1 to 1.1, it may be considered to be almost spherical. Silica oxide fine particles and the like produced by the VMC method are true spherical particles having an aspect ratio of nearly 1. Such spherical particles are particularly excellent in appearance such as a reinforcing effect as a dispersing material and surface gloss.
[0012]
By the way, if the surface of the ceramic primary particles is coated before granulation to the secondary particles, it is more excellent in dispersibility. As the surface treatment agent, there is a coupling agent or a surfactant. More specifically, for example, γ-glycidoxypropyltrimethoxysilane, silanes such as hexamethyldisilazane, titanates such as isopropyltriisostearoyl titanate, aluminates such as acetoalkoxyaluminum diisopropylate, zirconate Coupling agents, higher fatty acids such as stearic acid, anionic surfactants such as higher fatty acid alkali salts and alkyl sulfonates, cationic surfactants such as higher amine halogenates and quaternary ammonium salts, polyethylene Nonionic surfactants such as glycol alkyl ethers and fatty acid monoglycerides, and amphoteric surfactants such as amino acids.
[0013]
(2) Secondary particles The secondary particles preferably have a particle size of 100 μm to 5 mm, more preferably 355 μm to 3 mm, in addition to the primary particle occupation volume ratio. If the powder (fine powder) consisting of small secondary particles having a particle size of less than 100 μm is increased, adhesion or fixation tends to occur, and the fluidity is deteriorated. On the other hand, even if the particle size of the secondary particles is large, there is almost no problem, but when it is 5 mm or less, the handleability is good.
These secondary particles are produced by a roll press method, which will be described later, in addition to a rolling granulation method, a stirring granulation method, and the like. When the secondary particles are granulated, a binder for the primary ceramic particles is not always necessary. However, when an appropriate amount of an appropriate binder is used, secondary particles having excellent primary particle fluidity and dispersibility can be easily obtained.
[0014]
Examples of the binder include release materials such as paraffin wax, low molecular weight polyethylene and dimethyl silicone oil, vinyl polymers such as polyethylene, polypropylene and polyvinyl alcohol, acrylics such as polyacrylonitrile and polymethyl methacrylate, and methacrylic polymers. , Polyvinyl ether polymers such as polyvinyl methyl ether and polyvinyl ethyl ether, polyester polymers such as polyethylene terephthalate and polybutylene terephthalate, cellulose polymers such as sodium carboxymethyl cellulose and methyl cellulose, and liquid crystals such as poly (phenylene terephthalamide) Type polymers. Of course, since there is compatibility between the primary particles and the binder, for example, the ceramic primary particles may be silica particles and the binder may be paraffin.
[0015]
Further, when the amount of the binder is too large, the dispersibility of the primary particles is lowered, so that it is desirable that the amount is an appropriate ratio. For example, when the total volume fraction of secondary particles is 100%, the volume ratio occupied by the binder is 0.6 to 8%, more preferably 0.7 to 7%, and further 0 .86 to 4.3% is preferable. These binder occupying volume ratios correspond to 0.4 to 6% by weight, 0.5 to 5% by weight, and 0.6 to 3% by weight, respectively, when the entire secondary particles are 100% by weight. To do.
[0016]
(3) Use of ceramic powder The ceramic powder of the present invention is preferably used as a dispersion or filler in a matrix material. The matrix material may be a metal such as Al in addition to the resin. The resin used as the matrix material is a general resin such as a thermosetting resin such as phenol or epoxy, or a thermoplastic resin such as vinyl or polyimide.
For example, a ceramic-dispersed resin material in which silica fine particles are dispersed in an epoxy resin is preferable as a sealing material for semiconductor chips and the like. In particular, even if the semiconductor chip is highly integrated by ultrafine processing, the ceramic dispersed resin material can be injected into the details of the semiconductor chip because the ceramic particles of the present invention are excellent in fluidity and dispersibility.
[0017]
【Example】
Next, an Example is given and this invention is demonstrated more concretely.
(1) Embodiment (1) Embodiment 1
As the raw material ceramic fine particles (ceramic primary particles), spherical silica fine particles (particle diameter 0.5 μm: Admafine SO-C2) produced by a commercially available VMC method were prepared. 1 part of paraffin wax is added to 100 parts of silica fine particles (parts by weight, the same applies hereinafter) to a Laedige mixer (WB-75, manufactured by Taiheiyo Kiko Co., Ltd.) equipped with a crushing blade heated to 80 ° C. with a boiler. did. Then, the mixture was stirred and mixed for 15 minutes at a spindle rotation speed of 50 rpm and a crushing shaft rotation speed of 3000 rpm (mixing step).
[0018]
The mixture obtained in this mixing step was put into a commercially available compacting granulator, and secondary particles were granulated by a roll press method (granulation step). At this time, the compacting granulator has a powder supply rate of 100 kg / h, a roll rotational speed of 22 rpm, a roll hydraulic pressure of 17 MPa, a roll gap of 0.25 mm, a precompression screw rotational speed of 60 rpm, and a roll linear pressure (compression pressure) of 850 kN / m. I drove under the conditions of In addition, since it is difficult to measure the surface pressure accurately, the roll linear pressure obtained from the force applied to the roll and the roll width was used as an index.
In addition, the product immediately after performing this roll press method was a flake-like piece, and it was not necessary to crush (the same also in the following examples).
[0019]
(2) Example 2
To 100 parts of the same silica fine particles as in Example 1, a 30% strength toluene solution containing 0.6 parts of paraffin was dropped over 2 minutes, and then stirred and mixed for 15 minutes with the above-mentioned Laedige mixer. . The Roedige mixer was operated at a spindle speed of 50 rpm and a crushing axis speed of 3000 rpm without heating.
[0020]
Thereafter, the obtained mixture was dried by heating at 140 ° C. for 2 hours with a hot air circulation dryer (that is, toluene was removed).
Using the mixture after heat drying, the mixture was granulated by the same roll press method as in Example 1. However, the operating conditions of the compacting granulator are: powder supply rate 300 kg / h, roll rotation speed 30 rpm, roll hydraulic pressure 15 MPa, roll gap 1.0 mm, no precompression screw, roll linear pressure (compression pressure) 400 kN / m It was.
[0021]
(3) Example 3
In this example, the silica fine particles were directly fed into a compacting granulator without using a binder. The operating conditions are the same as in Example 2.
[0022]
(4) Example 4
While spraying 50 parts of isopropanol solution containing a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM403) as a surface treatment agent at a ratio of 2 parts to 100 parts of the same silica fine particles as in Example 1, The mixture was stirred and mixed for 10 minutes with a mixer. Thus, the surface treatment was performed on the silica fine particles. The Roedige mixer was operated at a main shaft rotation speed of 500 rpm and a crushing shaft rotation speed of 3000 rpm without heating.
[0023]
Thereafter, 1 part of paraffin wax was added, and the mixture was stirred and mixed for 15 minutes. At this time, the Laedige mixer was operated under the same conditions as in Example 1.
The mixture thus obtained was dried by heating at 120 ° C. for 5 hours with a hot air circulating dryer. And the secondary particle was granulated by the roll press method on the same conditions as Example 1 using the mixture after heat drying.
[0024]
(5) Example 5
In this example, only the addition amount of the paraffin wax mixed with the silica fine particles was changed from 1 part to 3 parts in Example 1, and other than that, the secondary particles were granulated in the same manner as in Example 1. It was.
[0025]
(6) Example 6
In this example, only the addition amount of the paraffin wax mixed with the silica fine particles was changed from 1 part of Example 1 to 5 parts, and other than that, the secondary particles were granulated in the same manner as in Example 1. It was.
[0026]
(7) Example 7
Fused silica fine particles were prepared in place of the silica fine particles, and the same granulation as in Example 1 was performed using the fused silica fine particles. The fused silica fine particles are obtained by melting commercially available pulverized silica (average particle size 0.7 μm) with a propane gas melting burner using a VMC silica production facility (average particle size 0.6 μm). .
[0027]
(2) Comparative Example (1) Comparative Example 1
To 100 parts of the same silica fine particles as in Example 1, a 30% strength toluene solution containing 1 part of paraffin was added dropwise over 2 minutes. Thereafter, the mixture was stirred for 10 minutes and granulated in the same manner as in Example 2. The obtained granulated material was dried by heating at 140 ° C. for 2 hours with a hot air circulating dryer.
[0028]
(2) Comparative example 2
To 100 parts of the same silica fine particles as in Example 1, 2 parts of isopropanol was added to a Ladige mixer. Thereafter, the mixture was stirred and granulated for 30 minutes in the same manner as in Example 2. The obtained granulated material was dried by heating at 140 ° C. for 2 hours with a hot air circulating dryer.
[0029]
(3) Comparative Example 3
For 100 parts of the same silica fine particles as in Example 1, 4 parts of water was put into a Laedige mixer. Thereafter, the mixture was stirred and granulated for 30 minutes in the same manner as in Example 2. The obtained granulated material was dried by heating at 140 ° C. for 10 hours with a hot air circulating dryer.
[0030]
(4) Comparative Example 4
One part of paraffin wax was added to a Ladige mixer with respect to 100 parts of the same silica fine particles as in Example 1. Thereafter, the mixture was stirred and mixed for 15 minutes in the same manner as in Example 1. The obtained mixture was put into a compacting granulator, and secondary particles were granulated by a roll press method. At this time, the compacting granulator has the following conditions: powder supply rate 80 kg / h, roll rotation speed 20 rpm, roll hydraulic pressure 10 MPa, roll gap 0.5 mm, no pre-compression screw, roll linear pressure (compression pressure) 150 kN / m Drove in.
[0031]
(5) Comparative Example 5
A slurry was prepared by mixing 20 parts of the same silica fine particles as in Example 1 with 80 parts of water. The slurry was supplied to a rotating disk type spray dryer (L-12, manufactured by Okawara Kako Co., Ltd.), and sprayed into dry air at 240 ° C. and dried to granulate secondary particles.
[0032]
(6) Comparative Example 6
Granulation was performed in the same manner as in Comparative Example 1 using the fused silica fine particles described in Example 7.
[0033]
(7) Comparative Example 7
Granulation was performed in the same manner as Comparative Example 5 using the fused silica fine particles.
[0034]
(3) Evaluation of secondary particles For each sample obtained in the above examples and comparative examples, the average particle size, fluidity (flow time) of secondary particles, dispersibility in resin, primary particle occupied volume Table 1 shows the ratio, the volume occupied by the binder (the volume occupied by paraffin), and the shape immediately after granulation. In addition, the characteristics of the ceramic primary particles (silica fine particles or fused silica fine particles) used in Examples and the like are also shown in Table 1 for reference.
[0035]
{Circle around (1)} The average particle diameter was determined for each of Examples 1 to 7, Comparative Examples 1 to 4 and Comparative Example 6 by a sieve separation method (weight basis). Comparative Examples 5 and 7 were determined by microscopic observation. Incidentally, the ceramic primary particles were measured by laser diffraction particle size distribution measurement (LA-500, manufactured by Horiba, Ltd.).
[0036]
(2) The fluidity was evaluated by the flow time. The flow time is the time required for filling a stainless steel funnel (φ150 × φ35 × H110 mm) with the powder, then opening the bottom of the funnel, and discharging the entire amount of the powder from the bottom.
In addition, "x" shown in Table 1 shows that the bridge | bridging was formed in powder and discharge | emission after that was not made | formed.
[0037]
(3) For dispersibility, a resin composite material in which various powders are dispersed in PET resin is actually manufactured, and the degree of aggregation of dispersed particles in the flakes (10 × 10 × about 0.02 mm) is observed with a microscope ( The magnification was 175 times). Table 1 shows 凝集 if the particle size of the agglomerates present in the flakes is 30 μm or less, ○ if the particle size is 30 to 70 μm, and x if the particle size is 70 μm or more.
The flakes were premixed with 50 parts of silica powder (secondary particles or ceramic primary particles) and 50 parts of PET pellets (TR4550BHK, Teijin) and melt-kneaded using a twin-screw extruder. The pellet is formed into a film having a thickness of about 20 μm by hot pressing.
[0038]
{Circle around (4)} The primary particle occupation volume ratio is obtained by changing the silica specific gravity (density: g / cc) of the granulated piece to the true specific gravity of silica (density: 2.21 (g / cc)) as shown in the formula (2). It was obtained by dividing by. Primary particle occupation volume ratio (%) = (silica specific gravity of granulated piece / 2.21) × 100 (2)
In addition, what is necessary is just to measure the specific gravity of a granulated piece by a generally well-known method. For example, a certain number of granulated pieces (plate-like or spherical) were obtained by dividing the weight by the volume obtained from microscopic observation. In the case where paraffin or the like is present in the secondary particles, the weight of the portion is excluded and the silica specific gravity of the granulated piece is taken.
[0039]
Moreover, the paraffin occupation volume ratio (binder occupation volume ratio) was similarly calculated | required by Formula (3).
Paraffin occupied volume ratio (%) = (specific gravity of paraffin of granulated piece / 0.92)
X100 (3) Here, the specific gravity of paraffin of the granulated piece = (paraffin weight / granulated piece volume), and the true specific gravity of paraffin is 0.92 (g / cc).
[0040]
(5) The silica fine particles used in the above examples or comparative examples are spherical with an aspect ratio of 1, and the fused silica particles have an indefinite angle with an aspect ratio of about 1.5 (reciprocal: 0.67). Shaped spherical particles. This aspect ratio is obtained as a ratio (D / d) of the major axis (D) to the minor axis (d) by measuring the particle diameter by microscopic observation.
[0041]
(6) Based on the above results, the correlation between the primary particle occupation volume ratio and the dispersibility or fluidity of the secondary particles is shown in FIG. As can be seen from the figure, when the primary particle occupation volume ratio is in the range of 50 to 65%, it is understood that both dispersibility and fluidity are excellent. On the other hand, when the primary particle occupation volume ratio exceeds 65% outside the range, the dispersibility deteriorates rapidly. Conversely, when the primary particle occupation volume ratio is less than 50%, the fluidity deteriorates rapidly. It became clear. In addition, the dispersibility in FIG. 1 displays the said 3 step | paragraph evaluation, and fluidity | liquidity displays the reciprocal number of the said flow time relatively.
[0042]
[Table 1]

[0043]
(4) Evaluation of Resin Composite Material Next, a composite material made of PET resin using the silica granulated powder made of the secondary particles produced in Example 4 and the powder of silica fine particles being the ceramic primary particles. Manufactured. And about the test piece, the result of having measured bending strength, bending elastic modulus, Tg (glass transition point), hygroscopicity (water absorption rate), Izod impact value, and linear expansion coefficient is shown in Table 2.
[0044]
In addition, the said test piece was manufactured as follows. First, 50 parts of ceramic powder (silica granulated powder or silica fine particles) and 50 parts of PET pellets (manufactured by Teijin, TR4550BHK) were premixed with a mixer, and melt-kneaded using a twin-screw extruder to be pelletized. The pellets were molded by an injection molding machine to produce the test piece.
[0045]
[Table 2]

[0046]
As understood from the above examples, when the ceramic powder according to the present invention was used, the dispersibility and fluidity of the secondary particles were good, and the characteristics of the obtained ceramic dispersed resin material were also good.
[0047]
【The invention's effect】
According to the ceramic powder of the present invention, both dispersibility in the matrix material and fluidity during production can be achieved.
[Brief description of the drawings]
FIG. 1 is a dispersion diagram showing the correlation between the volume fraction occupied by primary particles and the dispersibility and fluidity of secondary particles.

Claims (5)

A ceramic powder comprising secondary particles obtained by granulating ceramic primary particles having a particle size of 0.01 to 10 μm,
The secondary particles, Ri the primary particle volume ratio is the volume ratio of ceramic primary particles 50 to 65% der when the total volume ratio is 100%,
Ceramic powder the ceramic primary particles, wherein Rukoto such silica particles. The secondary particles contain a binder that binds the ceramic primary particles, and a binder occupied volume ratio that is a volume ratio occupied by the binder when the total volume ratio of the secondary particles is 100%. The ceramic powder according to claim 1, which is 0.6 to 8%. The ceramic powder according to claim 2, wherein the binder is paraffin. The ceramic powder according to claim 1, wherein the ceramic primary particles have been subjected to a surface treatment with a coupling agent or a surfactant. The ceramic powder according to claim 1, wherein the ceramic primary particles are true spherical particles having an aspect ratio of 1 to 1.1.

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