WO2001010958A1

WO2001010958A1 - Highly acid-resistant, hydration-resistant magnesium oxide particles and resin compositions

Info

Publication number: WO2001010958A1
Application number: PCT/JP2000/005147
Authority: WO
Inventors: Hitoshi Anabuki
Original assignee: Kyowa Chemical Industry Co., Ltd.
Priority date: 1999-08-06
Filing date: 2000-07-31
Publication date: 2001-02-15
Also published as: AU6183900A

Abstract

Magnesium oxide particles whose surfaces are treated with an acid phosphate ester represented by the general formula (1) and which exhibit high acid resistance and high hydration resistance; and synthetic resin compositions containing the magnesium oxide particles (wherein n is 1 or 2; and R is C4-C30 alkyl or C4-C30 alkenyl). The resin compositions permit high magnesium oxide contents and are excellent in fluidity and easy of molding. Articles molded from the compositions have high acid resistance and high hydration resistance, thus being valuable as materials of electronic or electrical components.

Description

Description Magnesium oxide particles and resin composition having high acid resistance and high hydration resistance Detailed description of the invention

Technical field to which the invention belongs

The present invention relates to magnesium oxide particles and a resin composition having high acid resistance and high hydration resistance.

More specifically, the present invention has a high melting point (about 2,800 ° C), high electrical insulation, low dielectric loss, high light transmission, high thermal conductivity, non-toxicity, basicity, etc. Adds high acid resistance, high hydration resistance and high fluidity to physical properties, and improves thermal conductivity of resin, heat-resistant material, electric insulating material, sealing material, sheathed heater filler, optical material, abrasive material, etc. The present invention relates to magnesium oxide particles useful for: The present invention also relates to a resin composition containing the magnesium oxide particles.

Conventional technology

Magnesium oxide particles are classified into lightly calcined magnesium oxide (about 600 to 900 ° C and dead calcined magnesium oxide (about 1,100 to 1,500 ° C). It utilizes the excellent chemical activity for neutralization of halogen and neutralization of halogen, and its typical use is, for example, an acid acceptor for halogenated rubber such as chloroprene and chlorosulfonated polyethylene. The latter is a heat-resistant container that makes use of the excellent physical properties of magnesium oxide particles, that is, its high melting point (about 2,800 ° C), high electrical insulation at high temperatures, translucency over a wide wavelength range, and high thermal conductivity. It is used for heat-resistant parts, heat-insulating materials, IC substrates, lenses, sodium lamp containers, sheathed heaters, fillers such as resins, abrasives, etc. However, magnesium oxide particles are gradually attacked by water or water vapor and become hydroxylated. There is a problem that magnesium particles are changed (hydrated) and the above-mentioned various excellent physical properties are lost, and the range of use is narrowed. Japanese Patent Application Laid-Open No. 8-85474 proposes a method of firing at a melting temperature of 1,600 ° C or higher and lower than a melting temperature (2,800 ° C). In the method of firing at a temperature of 600 ° C or higher and lower than the melting temperature of the magnesium oxide particles, the crystal growth of the magnesium oxide particles is poor for the firing temperature, and the firing results in a large mass, which requires strong grinding. However, the single crystal of the magnesium oxide particles that have grown so long is broken, and various lattice defects are generated on the crystal surface. For this reason, there was a problem that satisfactory hydration resistance was not exhibited, and at the same time, the external shape was irregular, the flowability was poor, and it was difficult to highly fill the resin.

Japanese Patent Application Laid-Open No. 61-36119 discloses that an aqueous solution containing a water-soluble magnesium salt is reacted with 1 to 3.5 equivalents of ammonia with respect to 1 equivalent of magnesium in the presence of magnesium hydroxide species. Magnesium hydroxide consisting of apparent spherical aggregates having an average secondary particle diameter of 5 to 500 / m is synthesized and calcined at 1,200 to 2,000 ° C. Suggest a way.

In this proposed method, a water-soluble magnesium salt aqueous solution is reacted with a predetermined amount of ammonia in the presence of magnesium hydroxide particles, and then calcined at 1,200 to 2,000 ° C. The magnesium oxide particles obtained have improved fluidity and resin filling properties compared to powdered products. Note that the powdered product is a coarse magnesium oxide particle (not spherical) having an irregular outer shape with an average particle diameter of about 10 to 20 m or less, which is obtained by mechanical pulverization. However, since the magnesium hydroxide particles before calcination are relatively large crystals and have a scaly shape, the sinterability is improved compared to the case of powdered magnesium hydroxide, but it is still unsatisfactory. And requires high temperature firing. In addition, not only the inside of the agglomerate but also the agglomerates are bonded to each other, so that strong pulverization is required. As a result, there is a problem that the hydration resistance is insufficient.

JP-A-62-28811 and JP-A-6-3-4117 disclose that magnesium oxide fine powder is surface-treated with an organic silicate compound, and then heat-treated. A method of forming a silica coating on the particle surface has been proposed.

In this proposed method, a method of forming a coating of a silane compound on the surface of magnesium oxide particles by surface-treating a fine powder of magnesium oxide with an organic silane compound is disclosed in US Pat. Since the surface of the magnesium oxide particles is coated with the silane compound, it provides magnesium oxide particles having improved hydration resistance per unit area over magnesium oxide itself. However, the hydration resistance is insufficient due to the large surface area, and the surface area is about

Since a large amount of 5 to 20 m ² Z g requires a large amount of organic silane, it is not economical and, of course, has a problem of lowering the excellent thermal conductivity of the magnesium oxide particles. I was

Japanese Patent Application Laid-Open No. 7-171928 solves the above-mentioned problems of the prior art, and has a high flowability, excellent workability, and a high resin content necessary for sufficient thermal conductivity improvement. We provide a method for producing magnesium oxide with a secondary particle size and high density that enables filling, and with high hydration resistance by firing at a lower temperature than conventional methods. Furthermore, by treating the above-mentioned highly hydrated magnesium oxide particles with an organic silane, the hydration-resistant magnesium oxide particles have a further excellent hydration resistance and can be highly filled into epoxy resin, polyester resin, polyolefin resin, silicone rubber, etc. In addition, the present invention provides a method for producing magnesium oxide particles capable of imparting sufficient thermal conductivity without decreasing the inherent mechanical strength and electrical properties of the resin by increasing the affinity between the magnesium oxide particles and the resin.

Problems to be solved by the invention

However, each application is often used in an atmosphere or under conditions where high humidity and contact with acidic substances are required, and there is still a problem of low acid resistance and low hydration resistance.

An object of the present invention is to provide magnesium oxide particles in which these problems are improved.

Another object of the present invention is to provide a resin composition which has a sufficient thermal conductivity, has a small decrease in mechanical strength, and provides a molded article having excellent properties as an electronic material.

Still another object of the present invention is to provide a resin composition which can provide a molded article having sufficiently satisfactory properties even at a high temperature and in an atmosphere in contact with an acidic substance even with a high filling composition of magnesium oxide particles. Is to do. Means for solving the problem

According to the study of the present inventors, the object of the present invention is to obtain the following formula (1)

0

II

(RO) _3-n P- (OH) _n (1) (wherein, n represents 1 or 2, R represents a C _{4 to} C ₃ alkyl group or a C _{4 to} C ₃ alkyl group) ,)

This is achieved by high acid resistance and high hydration resistance magnesium oxide particles surface-treated with an acid phosphate represented by the formula:

Another object of the present invention is to provide (A) 100 parts by weight of a synthetic resin and (B) 50 to 1,000 parts by weight of magnesium oxide particles surface-treated with an acidic phosphate represented by the above formula (1). This is achieved by a resin composition that substantially becomes.

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

In the present invention, the magnesium oxide particles have an average secondary particle diameter of 0.1 to 130 xm, preferably 0.5 to 50 m, as measured by a laser single light diffraction scattering method, and are also measured by a BET method. Advantageously, the specific surface area is between 0.1 and 5 m ² Zg, preferably between 0.1 and 3 m ² / g.

The magnesium oxide particles may be manufactured by various methods. For example, a method described in JP-A-6-171928, that is, high-dispersion magnesium hydroxide is fired at a predetermined temperature, and then the resulting fired material is pulverized and classified to a predetermined particle size so as not to substantially destroy the crystal. Those obtained by the method can be used. According to this method, magnesium oxide particles having high fluidity, high filling property and high hydration resistance can be obtained. The magnesium oxide particles are obtained by granulating and drying a highly dispersible magnesium hydroxide slurry by spray drying or the like, and firing at a predetermined temperature, preferably at a temperature of about 1,100 to 1,600 ° C. Magnesium oxide particles having an egg-like shape, which are preferable for the resin composition of the present invention.

The magnesium oxide particles of the present invention are those whose surfaces have been surface-treated with an acidic phosphoric acid ester represented by the above formula (1) (hereinafter referred to as “surface treating agent”). In the above formula (1), R is an alkyl group of C ₄ to (^. Or an alkenyl group of C _{4 to} C _3Q . And these alkyl or alkenyl groups may be linear or branched. Preferred R is, C ₈ ~C _2. Is an alkyl group. N is 1 or 2, which means that the phosphate ester may be either a monoester type or a diester type. Further, a mixture of a monoester type and a diester type may be used. Examples of phosphate esters are butyl acid phosphate, 2-ethyl hexyl acid phosphate, lauryl acid phosphate, tridecyl acid phosphate, stearyl acid phosphate, g2-ethyl hexyl phosphate, and o. Rail phosphate and the like. Of these, stearyl acid phosphate is most preferred.

When the magnesium oxide particles are subjected to the surface treatment, the amount of the surface treatment agent attached to the magnesium oxide particles is 0.1 to 10% by weight, preferably 0.5 to 7% by weight. If the amount of the surface treatment agent is less than the above range, the effect of improving water resistance and acid resistance is insufficient.If the amount is more than the above range, the effect of improving water resistance and acid resistance is not further improved. Conversely, there is a possibility that the mechanical strength such as tensile strength and Izod impact strength of a molded product obtained from the synthetic resin composition containing the magnesium oxide particles is reduced.

The surface treatment of the magnesium oxide particles with the surface treatment agent is a method of directly heating the magnesium oxide particles and the surface treatment agent; the surface treatment agent dissolved in the organic solvent is directly sprayed or mixed on the magnesium oxide particles. A method of adding a surface treating agent dissolved in an organic solvent to a magnesium oxide slurry suspended in an organic solvent, mixing and separating the organic solvent, volatilizing and removing, and the like can be used. Magnesium oxide particles surface-treated by these methods not only have excellent acid resistance and hydration resistance, but also have high fluidity and high filling properties.

Since the magnesium oxide particles surface-treated with the above-mentioned acidic phosphate ester have remarkably excellent acid resistance and hydration resistance, the advantage can be remarkably exhibited by blending the particles with a synthetic resin. . As the synthetic resin, those conventionally used as a high thermal conductive material or an electrical insulating material by mixing magnesium oxide particles can be advantageously used. Examples of synthetic resins include epoxy resin Resin, silicone resin, phenol resin, diaryl phthalate resin, polyimide resin, polyphenylene sulfide resin, acrylic rubber, butyl rubber, ethylene propylene rubber, ethylene acetate biel copolymer, ethylene acrylate copolymer or fluorine resin, etc. Is mentioned. Of these, epoxy resins or silicone resins are preferred, and epoxy resins are particularly suitable for the resin composition of the present invention. Specific examples of epoxy resins include 4,4'-bis (2,3-epoxypropoxy) biphenyl and 4,4'-bis (2,3-epoxypropoxy) 3,3'5,5'- Tetramethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) 1,3,3'5,5'-tetraethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) Biphenyl type epoxy resin having biphenyl skeleton, such as -3,3'5,5, -tetramethyl-2-chlorochlorophenyl; 1,5-di (2,3-epoxypropoxy) naphthalene, 1,6- Di (2,3—epoxypropoxy) naphthene-type epoxy resin such as naphthylene; 4,4'-bis (2,3-epoxypropoxy) stilbene; 4,4'-bis (2,3) —Epoxypropoxy) 1,3'5,5'-Tetramethylstilbe Cresol novolak epoxy resin; phenol novolak epoxy resin; novolak epoxy resin such as bisphenol A skeleton-containing novolak epoxy resin; phenol aralkyl epoxy resin; naphthol aralkyl epoxy resin Examples include arylalkyl type epoxy resins such as silicone resins; epoxy resins having a dicyclopentene skeleton; polyfunctional epoxy resins such as tris (2,3-epoxypropoxy) phenylmethane. Among them, bifunctional epoxy resins such as biphenyl type epoxy resin, naphthylene type epoxy resin and stilbene type epoxy resin are particularly preferably used.

In the resin composition of the present invention, (B) the magnesium oxide particles are 50 to 100 parts by weight, preferably 60 to 500 parts by weight, based on 100 parts by weight of the synthetic resin (A). More preferably, it is blended in an amount of 70 to 400 parts by weight. The mixing of the synthetic resin and the magnesium oxide particles is carried out by a commonly known means in kneading a filler and a resin. ADVANTAGE OF THE INVENTION According to this invention, a magnesium oxide particle can be highly filled into a resin, and since the obtained composition also has excellent fluidity, it is excellent in moldability. Molded articles formed from the resin composition have good acid resistance and hydration resistance, and molded articles highly filled with magnesium oxide have high thermal conductivity. It can be used advantageously as a component material.

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

Example

Example 1

Magnesium hydroxide having an average secondary particle diameter of 0.80 // m and a BET specific surface area of 6.3 m ² Zg was calcined at 1,300 ° C to obtain magnesium oxide. This magnesium oxide was pulverized and classified. The obtained magnesium oxide particles have an average secondary particle diameter of about 2 m, a maximum particle diameter of 16 wm, and a BET specific surface area of 1.6 m ² Zg, as measured by a laser single light diffraction scattering method, and are observed with a scanning electron microscope. As a result, the particles were almost spherical magnesium oxide particles.

100 kg of the obtained magnesium oxide particles was put into a Henschel mixer manufactured by Mitsui Miike Seisakusho Co., Ltd. A solution prepared by dissolving lkg of stearyl acid phosphate in 20 liters of ethanol at 60 ° C was gradually added with stirring. After stirring for minutes, the mixture was heated to 80 ° C. or higher to remove the solvent ethanol.

Next, an acid resistance test was performed using an automatic squirt titrator AUT-21 manufactured by Toa Denpa Kogyo KK. The details are shown below.

0.5 g of magnesium oxide particles treated with stearyl acid phosphate are suspended in 50 cc of a mixed solution of ethanol: water = 1: 1, and the pH is lowered by dropping 0.1 N-nitric acid with stirring. While maintaining at 4.0, the consumption of 0.1N-nitric acid after a certain time was measured. The results are shown in Table 1.

In the hydration resistance test, stearyl acid phosphate-treated magnesium oxide was mixed with 2.5 times (weight ratio) of water, and the weight gain after drying at 105 ^DC for 2.5 hours was measured. The results are shown in Table 2.

Comparative Example 1 The same acid resistance test and hydration resistance test as in Example 1 were performed using the magnesium oxide particles before the stearyl acid phosphate treatment of Example 1.

Comparative Example 2

The same surface treatment and acid resistance test and hydration resistance test as in Example 1 were completed using vinyltriethoxysilane instead of stearyl acid phosphate in Example 1, and the test was completed.

Comparative Example 3

The vinyltriethoxysilane-treated magnesium oxide particles of Comparative Example 2 were fired at 800 ° C. for 1 hour, and subjected to the same acid resistance test and hydration resistance test as in Example 1. Tables 1 and 2 show the results of Example 1 and Comparative Examples 1, 2, and 3. table 1

Table 2

Example 2 and Comparative Examples 4 to 6

The respective magnesium oxide particles obtained in Example 1 and Comparative Examples 1 and 2 were blended in an epoxy resin at a ratio satisfying the following blending conditions, and the resulting composition was stirred and kneaded while being pulled by a vacuum pump. Then a stainless steel bat (8 cmX 1 2 cmX 3 cm), pre-cured (110 ° C, 2 hours), and post-cured (150 ° C, 3 hours). The thermal conductivity and the water absorption of the obtained molded product were measured. The results are shown in Table 3.

The case where no magnesium oxide particles were added was shown as Comparative Example 4.

The water absorption and the thermal conductivity were measured by the following methods.

1) Water absorption

The weight change was measured using a thermo-hygrostat (Advantech Toyo AGX-326) at 85 ° C and 85% RH.

2) Thermal conductivity

It was measured by a probe method using a QTM rapid thermal conductivity meter manufactured by Kyoto Electronics Industry Co., Ltd.

Blending conditions;

Epoxy resin (Epicoat 828, manufactured by Yuka Shell) 100 咅 15 Hardener (Rikasid MH-700, manufactured by Shin Nippon Rika) 80 parts Hardening accelerator (BDMA, manufactured by Koei Chemical) 1 part Magnesium oxide particles 300 咅 15 The magnesium particles obtained were the particles of Example 1 in Example 2, the particles of Comparative Example 1 in Comparative Example 5, and the particles of Comparative Example 2 in Comparative Example 6.

Table 3 Example 2 Comparative Example 4 Comparative Example 5 Comparative Example 6 Epoxy resin 100 00 100 100 Curing agent 80 80 80 80 Curing accelerator 1 1 1 1 Magnesium oxide particles 300 300 300 Surface treatment agent Stearyl acid vinyl triet

Phosphate xysilane Thermal conductivity (WZm · k) 0.704 0.18 1 0.709 0.6963 Water absorption (%) 0.37 0.65 65.45 0.40

Claims

The scope of the claims

1. The following equation (1)

0

II

(RO) _3-n P- (OH) _n (1)

(In the formula, n 1 or 2, R is C ₄ ~ (:. ₃ alkyl group or a C ₄ -C ₃ are shown the Aruke group,).

Highly acid-resistant and hydration-resistant magnesium oxide particles surface-treated with an acid phosphate represented by the formula:

2. The magnesium oxide particles according to claim 1, wherein said magnesium oxide particles have an average secondary particle diameter of 0.1 to 130 ^ m.

3. The magnesium oxide particles according to claim 1, wherein the magnesium oxide particles have a BET specific surface area of 0.1 to 5 m ² / g.

4. The magnesium oxide particles according to claim 1, wherein the magnesium oxide particles have a spherical or egg-like particle shape.

5. In the acidic phosphate ester, R is C _{8 to} C ₂ in the formula (1). The magnesium oxide particles according to claim 1, which is a compound of an alkyl group represented by the formula:

6. The magnesium oxide particles according to claim 1, wherein the total amount of the acidic phosphate represented by the formula (1) is 0.1 to 10% by weight.

7. (A) 100 parts by weight of synthetic resin and

(B) A resin composition comprising 50 to 1,000 parts by weight of the magnesium oxide particles according to claim 1.

8. (A) 100 parts by weight of synthetic resin and

(B) The resin composition according to claim 7, which is substantially 70 to 400 parts by weight of the magnesium oxide particles according to claim 1.

9. The synthetic resin is an epoxy resin, a silicone resin, a phenol resin, a diaryl phthalate resin, a polyimide resin, a polyphenylene sulfide resin, an acrylic rubber, a butyl rubber, an ethylene propylene rubber, an ethylene vinyl acetate copolymer, or an ethylene acrylate copolymer. 8. The resin composition according to claim 7, which is a polymer or a fluororesin.

10. The resin composition according to claim 7, wherein the synthetic resin is an epoxy resin.

1 1. A molded article formed from the resin composition according to claim 7.

12. An electronic material sealing agent formed from the resin composition according to claim 7.

13. An electrical insulating material formed from the resin composition according to claim 7.