JP4774236B2 - Magnesium hydroxide particles, method for producing the same, and resin composition containing the same - Google Patents

Description

  The present invention relates to magnesium hydroxide particles excellent in environmental properties, flame retardancy, and fluidity, filling properties, dispersibility, and economic efficiency for a resin, a method for producing the same, and a resin containing the magnesium hydroxide as a flame retardant. Relates to the composition.

  Magnesium hydroxide does not generate toxic gas during sintering and is excellent in environmental properties. Therefore, it is blended as a flame retardant in a resin composition, for example, a resin composition for sealing a semiconductor device. Such magnesium hydroxide flame retardant is required not only to have good flame retardancy but also to have good properties such as good filling property to the resin.

  In the conventional magnesium hydroxide flame retardant, fine crystals of magnesium hydroxide aggregate to form an aggregate having an average secondary particle size of about 10 to 100 μm. Therefore, when this magnesium hydroxide flame retardant is added to the resin, there is a problem that the dispersibility is poor and the function as the flame retardant is not sufficiently exhibited.

  Therefore, a method for producing magnesium hydroxide having an arbitrary particle size and good dispersibility (Patent Document 1), a method for producing magnesium hydroxide of hexagonal columnar crystals by a hydrothermal synthesis process under high temperature and high pressure (Patent Document 2), Specially shaped magnesium hydroxide composite with improved fluidity (Patent Document 3), one specifying the particle size distribution of polyhedral complex metal hydroxide (Patent Document 4), and mineral-derived magnesium hydroxide A flame retardant whose surface is coated with a surface treatment agent that regulates the content of impurities such as iron (Fe) compounds and silicon (Si) compounds, and specifies the average particle size and particle size distribution (Patent Document 5). Proposed.

  However, the above-mentioned magnesium hydroxide flame retardants are not necessarily satisfactory in terms of dispersibility and fluidity when blended with resin, or the manufacturing process is complicated and expensive, and it is still improved. There is room for. In particular, the hexagonal columnar magnesium hydroxide particles described in Patent Document 2 are flat and insufficient in thickness, and the polyhedral magnesium hydroxide particles described in Patent Document 3 also have a sufficient crystal thickness. However, both have not achieved satisfactory liquidity.

JP-A 63-277510 Japanese Patent Laid-Open No. 03-170325 Japanese Patent Laid-Open No. 11-11945 JP 2000-53876 A JP 2003-3171 A

  The object of the present invention is to solve the above-mentioned problems and to have good fluidity, filling property and dispersibility when blended in a resin, and excellent in environmental properties at the time of combustion. A method for producing magnesium oxide, a resin composition containing this magnesium hydroxide as a flame retardant, and a semiconductor device using this resin composition as a sealant are provided.

  In order to solve the above problems, the present inventors have made various studies. As a result, the inventors focused on the crystal shape of the magnesium hydroxide particles, and have a hexagonal column shape, which is much thicker than the conventional crystal. It has been found that an excellent effect can be obtained when magnesium hydroxide particles that are large, that is, having a hexagonal column shape and sufficiently grown in the c-axis direction, are used as a flame retardant material. Furthermore, the inventors have found a production method capable of obtaining magnesium hydroxide particles sufficiently grown in the c-axis direction with a smaller number of steps than the conventional method, and have completed the present invention.

That is, according to the present invention, the crystal outer shape is hexagonal prism-shaped particles composed of two parallel upper and lower hexagonal basal planes and six outer peripheral prismatic planes formed between these basal planes. Thus, magnesium hydroxide particles having a size in the c-axis direction of the hexagonal column-shaped particles of 1.5 × 10 ^{−6 to} 6.0 × 10 ⁻⁶ m are provided.

The magnesium hydroxide flame retardant of the present invention has a hexagonal column shape as shown in FIG. 1 and includes magnesium hydroxide particles whose c-axis direction size (hereinafter referred to as “Lc”) is within a predetermined range. Specifically, Lc is 1.5 × 10 ^{−6 to} 6.0 × 10 ⁻⁶ m, and Lc is 1.5 × 10 ^{−6 to} 3.0 × 10 ⁻⁶ m. More preferred.

When Lc is 1.5 × 10 ⁻⁶ m or more, the filling property and fluidity of the magnesium hydroxide particles to the resin are improved. This indicates that the larger the value of Lc, the more the hexagonal columnar particles are developed in the c-axis direction. Some interaction exists at the interface between the magnesium hydroxide particles and the resin, and the particle shape causes the free movement of the resin to be constrained. In general, this tendency is affected by the particle shape. In other words, the effect increases as the degree of shape anisotropy increases. This is because the magnesium hydroxide particles of the present invention are particles sufficiently grown in the c-axis direction, so that they have a smaller shape anisotropy than the conventional particles and there are few factors that hinder the free movement of the resin. In addition, although the average particle diameter d of a magnesium hydroxide particle is not specifically limited, Usually, it is preferable to set it as the range of 0.1 * 10 < ^-6 > -10 * 10 <^-6> m.

  In the present invention, the size Lc of the magnesium hydroxide particles in the c-axis direction is a measured value of the particles having the maximum length in the field of view in the scanning electron microscope observation, and the volume V is the basis of the particles. The length of the hexagonal piece of the surface was measured and calculated. Further, the average particle diameter d of the magnesium hydroxide particles is a value of a 50% diameter of the powder sample measured by a particle size distribution measuring apparatus by a laser diffraction / scattering method.

Further, the magnesium hydroxide particles of the present invention having Lc in a predetermined range described above, preferably has a volume of ^{8.0 × 10 -18 ~600 × 10 -18} m 3. Furthermore, the magnesium hydroxide particles of the present invention are preferably obtained by hydrating magnesium oxide having a crystallite diameter of 50 × 10 ⁻⁹ m or more. This is because magnesium oxide in which crystals having a large crystallite diameter have developed has low hydration activity, so that formation of fine particles is suppressed and magnesium hydroxide that grows greatly in the c-axis direction can be obtained. The crystallite diameter is a value calculated by the Scherrer equation using the X-ray diffraction method.

In the method for producing magnesium hydroxide of the present invention, MgO powder having a crystallite diameter of 50 × 10 ⁻⁹ m or more obtained by pulverizing and sieving a magnesium oxide (MgO) raw material is added to an organic acid at 100 ° C. It includes the steps of adding the following warm water, then carrying out a hydration reaction of MgO under high shear stirring, and then filtering off the generated solid, washing with water and drying.

  Although it does not specifically limit as said organic acid, Preferably, monocarboxylic acid, oxycarboxylic acid (oxyacid), etc. are mention | raise | lifted. Examples of the monocarboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, acrylic acid, crotonic acid, and the like. Examples of the oxycarboxylic acid (oxyacid) include glycolic acid, lactic acid, Examples include hydroacrylic acid, α-oxybutyric acid, glyceric acid, salicylic acid, benzoic acid, and gallic acid.

In the method for producing magnesium hydroxide of the present invention, MgO used as a raw material is not particularly limited as long as the crystallite diameter is 50 × 10 ⁻⁹ m or more, but was obtained by an electrofusion method. It is preferable that magnesium hydroxide particles having a predetermined thickness can be obtained by only one hydration reaction by using electrofused MgO.

  The above hydration reaction is performed under high shear stirring in warm water of 100 ° C. or lower, for example, 50 to 100 ° C. Specifically, it is preferable to use a high-speed stirrer equipped with turbine blades. The temperature of the hot water is preferably 60 to 100 ° C.

The average particle diameter d of the magnesium hydroxide particles obtained here is 0.5 × 10 ^{−6 to} 1.0 × 10 ⁻⁶ m, and this is used as a seed crystal during the new hydration reaction. By being present in a proportion, magnesium hydroxide particles having a larger particle size and having the predetermined Lc of the present invention can be obtained. Then, the initially obtained small particle size magnesium hydroxide particles and the latter large particle size magnesium hydroxide particles are mixed by a dry method using a V-type mixer or the like, or wet in a slurry state after hydration. By stirring and mixing, it is possible to further improve the filling property to the resin.

  Further, after the above hydration reaction, the obtained magnesium hydroxide may be subsequently subjected to various surface treatments by known methods. Examples of the surface treatment agent for increasing the affinity for the resin include higher fatty acids or alkali metal salts thereof, phosphate esters, silane coupling agents, fatty acid esters of polyhydric alcohols, and the like.

  On the other hand, in order to increase acid resistance, water repellency, etc., for example, by coating with silica metal salt by baking at about 500 to 1000 ° C. after alumina coating, silica coating, silicone oil, polyfluoroalkyl phosphate ester salt, etc. Examples of the surface treatment method include coating. In order to enhance the ultraviolet absorptivity, for example, a surface treatment method in which titanyl sulfate is hydrolyzed to coat titanium dioxide can be used. A plurality of these surface treatments may be combined.

  In the process of producing the above magnesium hydroxide particles, as described in JP-A-11-11945, a zinc compound such as zinc oxide or zinc chloride is added, and the magnesium hydroxide is mixed with a composite metal hydroxide. It is also possible to manufacture as a product.

  The resin composition of the present invention is obtained by kneading together with an epoxy resin, a curing agent, an inorganic filler, etc., using magnesium hydroxide obtained as described above as a flame retardant. In this resin composition, the compounding amount of the magnesium hydroxide flame retardant is preferably 1 to 35% by mass of the entire resin composition, and more preferably the total of the inorganic substances, that is, the magnesium hydroxide flame retardant and the inorganic It is to make the total compounding quantity with a filler be 60-95 mass% of the whole resin composition.

  The above resin composition is excellent in environmental resistance such as flame retardancy, moisture resistance, and acid resistance, and is useful as a sealing agent for semiconductors. Therefore, various semiconductors sealed with this resin composition The device can be manufactured.

  The method for preparing the semiconductor sealing resin composition is not particularly limited as long as various raw materials can be uniformly dispersed and mixed. Specific examples include, for example, sufficient mixing with a mixer, etc., melt-kneading with a mixing roll, an extruder, etc., cooling, pulverizing, and molding this into granules, dimensions and weight that match the molding conditions Or a mixture of each component of the resin composition received on a pallet, and after cooling it, press rolling, roll rolling, or a mixture of solvent is applied to form a sheet, etc. It can be made into various forms such as one formed into a sheet by a method.

  The method for sealing a semiconductor element using the resin composition for sealing a semiconductor thus obtained is not particularly limited, and for example, a known molding method such as ordinary transfer molding can be used.

  EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples.

Synthesis example 1
<Manufacture of magnesium hydroxide particles>
Electrofused MgO having a crystallite diameter of 58.3 × 10 ⁻⁹ m (manufactured by Tateho Chemical Co., Ltd.) was pulverized with a ball mill and passed through a 200-mesh sieve by a wet method. The particles that passed through the sieve were added to a 20 L container with 10 L of acetic acid having a concentration of 0.02 mol / L so that the oxide (MgO) concentration was 100 g / L. While maintaining the obtained MgO-containing mixed solution at 90 ° C., using a high-speed stirrer (trade name: Homomixer, manufactured by Tokushu Kika Co., Ltd.), stirring the peripheral speed of the turbine blade at 10 m / s for 4 hours A hydration reaction was performed. The obtained reaction product was passed through a 500 mesh sieve, and the fine particles that passed through the sieve were subsequently filtered, washed with water, and dried to obtain magnesium hydroxide particles. Table 1 shows the particle shape, size (Lc) and volume (V) of the obtained magnesium hydroxide particles in the c-axis direction. Further, a scanning electron micrograph of the obtained magnesium hydroxide particles is shown in FIG.

<Evaluation test>
The magnesium hydroxide particles were kneaded with the epoxy resin at the ratio shown in Table 2, and the spiral flow and flame retardancy of the obtained resin composition were measured under the following conditions. The results are shown in Table 2. Here, the spiral flow is a value representing the fluidity of the thermoplastic resin and the thermosetting resin.
The epoxy resin is a cresol novolac type epoxy resin (epoxy equivalent 198), the curing agent is a phenol novolac resin (hydroxyl equivalent 105), the curing accelerator is triphenylphosphine, and the inorganic filler is a spherical melt. Each silica was used.

(Flame resistance measurement method)
A flame retardant test piece having a thickness of 1/16 inch was prepared using the epoxy resin composition (molding conditions: temperature 175 ° C., time 120 seconds, post cure 175 ° C. × 6 hours), UL-94 V-0 standard The flame retardancy was evaluated according to the method.
(Spiral flow measurement method)
A spiral flow value was measured according to EMMI 1-66 using a spiral flow measurement mold under the conditions of a temperature of 175 ° C. and a pressure of 6086 MPa.

Example 1
The same operation as in Synthesis Example 1 was carried out except that 30 g of the magnesium hydroxide particles obtained in Synthesis Example 1 were previously suspended in 10 L of 0.02 mol / L acetic acid as seed crystals. Thus, magnesium hydroxide particles obtained by further crystal growth from the particles obtained in the above were obtained. Each numerical value representing the particle shape of the magnesium hydroxide particles is shown in Table 1, and a scanning electron micrograph is shown in FIG. And this magnesium hydroxide particle was knead | mixed with the epoxy resin in the ratio shown in Table 2, the spiral flow and flame retardance of the obtained resin composition were measured on said conditions, and the result was shown in Table 2.

Example 2
500 g of the magnesium hydroxide particles obtained in Synthesis Example 1 and 500 g of the magnesium hydroxide particles obtained in Example 1 were placed in a V-type mixer and mixed for 20 minutes to obtain magnesium hydroxide particles. Each numerical value representing the particle shape of the magnesium hydroxide particles is shown in Table 1, and a scanning electron micrograph is shown in FIG. And this magnesium hydroxide particle was knead | mixed with the epoxy resin in the ratio shown in Table 2, the spiral flow and flame retardance of the obtained resin composition were measured on said conditions, and the result was shown in Table 2.

Comparative Example 1
As the magnesium hydroxide particles, Echo Mag (registered trademark) Z-10 manufactured by Tateho Chemical Industry Co., Ltd. was used as it was. Each numerical value representing the particle shape of the magnesium hydroxide particles is shown in Table 1, and a scanning electron micrograph is shown in FIG. And this magnesium hydroxide particle was knead | mixed with the epoxy resin in the ratio shown in Table 2, the spiral flow and flame retardance of the obtained resin composition were measured on said conditions, and the result was shown in Table 2.

Comparative Example 2
Fine magnesium (registered trademark) MO manufactured by TMG Corporation was used as it was as magnesium hydroxide particles. Each numerical value representing the particle shape of the magnesium hydroxide particles is shown in Table 1, and a scanning electron micrograph is shown in FIG. And this magnesium hydroxide particle was knead | mixed with the epoxy resin in the ratio shown in Table 2, the spiral flow and flame retardance of the obtained resin composition were measured on said conditions, and the result was shown in Table 2.

As apparent from the results in Table 2, the magnesium hydroxide particles of the present invention include magnesium hydroxide particles having Lc of 1.5 × 10 ^{−6 to} 6.0 × 10 ⁻⁶ m. When kneaded into a resin as a flame retardant, it was confirmed that the spiral flow was larger and the flowability was better than conventional magnesium hydroxide particles.

  From the above, the magnesium hydroxide flame retardant of the present invention is excellent in flame retardancy and resin filling properties, and can be produced at a low cost by a single hydration reaction. It is also economical. Therefore, it is extremely useful as a filler for sealing resins in semiconductor devices such as transistors, ICs, and LSIs, and its industrial value is extremely large.

It is explanatory drawing which shows the external shape of the magnesium hydroxide particle of this invention. 2 is a scanning electron micrograph showing the magnesium hydroxide of Synthesis Example 1. 2 is a scanning electron micrograph showing magnesium hydroxide of Example 1. FIG. 2 is a scanning electron micrograph showing magnesium hydroxide of Example 2. FIG. 2 is a scanning electron micrograph showing magnesium hydroxide of Comparative Example 1. 4 is a scanning electron micrograph showing magnesium hydroxide of Comparative Example 2.

Claims (7)

A hexagonal columnar particle having a hexagonal basal plane of two upper and lower surfaces parallel to each other and six outer peripheral prismatic surfaces formed between these basal planes, Magnesium hydroxide particles having a size in the c-axis direction of 1.5 × 10 ^{−6 to} 6.0 × 10 ⁻⁶ m. The magnesium hydroxide particle according to claim 1, wherein the magnesium hydroxide particle has a volume of 8.0 × 10 ⁻¹⁸ to 600 × 10 ⁻¹⁸ m ³ . The magnesium hydroxide particle according to claim 1, wherein the magnesium hydroxide particle is obtained by hydrating magnesium oxide having a crystallite diameter of 50 × 10 ⁻⁹ m or more. (A) epoxy resin,
A resin composition comprising (b) a curing agent, (c) an inorganic filler, and (d) a magnesium hydroxide particle according to any one of claims 1 to 3 . The resin composition of Claim 4 whose compounding quantity of the said magnesium hydroxide particle is 1-35 mass% of the said resin composition. The semiconductor sealing agent which consists of a resin composition of Claim 4 or 5 . A semiconductor device using the semiconductor sealing agent according to claim 6 .