JPH03122014A - Coarse aluminum hydroxide for filler and method for producing the same - Google Patents

Abstract

PURPOSE:To obtain a coarse aluminum hydroxide for filler, having excellent mechanical strength and optical properties, by forming a mixture of aluminum hydroxide and an inorganic binder into particles having specific particle diameters and heat-treating. CONSTITUTION:Aluminum hydroxide is blended with an inorganic binder, formed into particles having >= 100 mu average particle diameter and heat-treated to give a coarse aluminum hydroxide having >= 100 mu average secondary particle diameter. When an aluminum hydroxide having <= 1mu secondary particle diame ter is used, a large amount of binder is required, light transmission properties as filler is deteriorated and prepared artificial marble has reduced physical properties such as whitening. Aluminum hydroxide forms secondary particles by aggregation of primary particles, an aluminum hydroxide applied, having usually >= about 0.5mu primary particle diameter is preferably used because the aluminum hydroxide becomes aluminum hydroxide having excellent light transmission properties.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to aluminum hydroxide for use as a filler, which has excellent mechanical strength and optical properties.

More specifically, 10 has excellent mechanical strength and translucency.
The present invention relates to aluminum hydroxide for use as a filler, which is suitable as a raw material for artificial marble and the like and has an average secondary particle size of 0 μm or more.

<Conventional technology> In recent years, there has been a remarkable trend toward luxury products such as bathroom vanities, bathtubs, kitchen products, interior decorations, and garden stones.
Materials that are closer to the real thing, or materials that mimic the appearance of the real thing but have a functional beauty that only exists in artificial materials (for example, providing a material that has a uniform surface condition even over a wide area, or a material that has a color tone that matches its surroundings) There are high hopes for the provision of materials that pursue the following.

As is well known, artificial marble is currently manufactured by dispersing and mixing aluminum hydroxide as a filler in methyl methacrylate resin or unsaturated polyester resin, heating and melting the mixture and molding it into the desired shape. Aluminum oxide has an average secondary particle diameter of several micrometers to 7 to 80 micrometers, and if it is used as a filler for artificial marble as it is, only pure white fine powder will be dispersed in the resin matrix, which is unique to marble. It is not possible to obtain the crystal-like appearance of porphyrite, etc., or the crystal-like appearance of biotite, etc., in granite.

Therefore, as a filler for comb stone-like artificial marble, there is a method in which the same resin as the matrix is kneaded with aluminum hydroxide as a binder, which is then molded and crushed to be used as aluminum hydroxide for filler. Although this method has been proposed, it has the drawbacks of high processing cost, inconveniences that may arise due to the difference between the resin used as the binder and the resin that forms the matrix, and poor versatility.

(Problem to be solved by the invention) In view of the above circumstances, the present inventors have developed a material that is inexpensive, unaffected by the resin used, and has excellent mechanical strength and translucency that can emphasize its presence in the matrix. As a result of intensive studies, we have completed the present invention.

Means for Solving the Problems) That is, the present invention provides coarse aluminum hydroxide for fillers having an average secondary particle size of 100 μm or more, which is obtained by bonding aluminum hydroxide with an inorganic binder, and furthermore, Coarse aluminum hydroxide for filler with an average secondary particle size of 100 μm or more, characterized by mixing aluminum hydroxide and an inorganic binder, shaping the mixture so that the average secondary particle size is 100 μm or more, and then heat-treating the mixture. The present invention provides a method for manufacturing.

The present invention will be explained in more detail below.

The aluminum hydroxide used as the inorganic binder in the present invention is not particularly limited as long as it is aluminum hydroxide used as a filler, but aluminum hydroxide obtained by the Bayer method is usually used.

These aluminum hydroxides have an average secondary particle diameter of about 1 μm or more, usually about 10 μm or more, preferably about 50 μm or more.

- When using aluminum hydroxide with a particle size of 1 μm or less, a large amount of binder is required, which deteriorates the translucency as a filler and causes a decrease in physical properties such as hot water whitening resistance of the resulting artificial marble. .

In aluminum hydroxide, primary particles aggregate to form secondary particles, and the aluminum hydroxide used in the present invention usually has a primary particle size of about 0.5 μm or more, more preferably about 1 μm or more. This is preferable because aluminum hydroxide for fillers can have excellent translucency.

Examples of the inorganic binder used in the present invention include sodium silicate and aluminum phosphate.

The amount of these inorganic binders added to aluminum hydroxide is not unique depending on the average particle size of the raw material aluminum hydroxide, the strength required of aluminum hydroxide after molding, etc., but in the case of sodium silicate, for example, Na2
O・n5io□, molar composition n・2~4, SiO□ is 23
When using ~37% by weight water glass, approximately 0.1 to approximately 10% by weight based on aluminum hydroxide (dry body basis);
Preferably, it may be used in an amount of about 3 to about 5% by weight.

The inorganic binder and aluminum hydroxide are kneaded so as to be uniform, and the aluminum hydroxide is bonded with the inorganic binder to form an average secondary particle size of about 100 μm or more, preferably about 100 μm or more to 1 mm.

Of course, it may be formed to a size larger than about 500 μm to about 1 mm, then pulverized and then heat treated, or it may be pulverized to a desired size after the heat treatment.

The molding method is not particularly limited as long as it is a known granulation method such as dish granulation, centrifugal granulation, or pressure granulation, but a pressure molding method such as roll compression is used. In some cases, aluminum hydroxide with a high particle packing density can be obtained (usually pressurized to aim for a bulk density of about 1.8 gre! or more), and coarse aluminum hydroxide for filling with high translucency can be obtained, so the pressure molding method is used. is recommended.

The formed aluminum hydroxide is then subjected to heat treatment.

The heat treatment method is not particularly limited, and usually about 1
What is necessary is just to heat it at 00-200 degreeC for 1-24 hours.

When such treatment is applied, the bonding strength between the inorganic binder and aluminum hydroxide is increased, resulting in a filler with excellent mechanical strength.When kneaded with the resin that becomes the matrix, the aluminum hydroxide as a filler collapses and the matrix becomes weaker. This is preferable because it does not cause any inconvenience such as a decrease in light transmittance.

In the present invention, only a mixture of an inorganic binder and aluminum hydroxide is exemplified as a raw material, but the present invention also includes the addition of fillers such as limescale, calcium carbonate, etc., or dyes and pigments to the extent that the characteristics of the present invention can be achieved. However, it may be molded and heated to be used as coarse aluminum hydroxide for filler. For example, when carbon black is added to an inorganic binder and aluminum hydroxide to form coarse aluminum hydroxide by the method of the present invention, granite It can be an excellent filler for finished artificial marble.

(Effects of the Invention) As detailed above, the aluminum hydroxide for filler of the present invention is inexpensive and has excellent mechanical strength and translucency, and when applied as a filler for artificial marble, it has a texture that is more like the real thing. Moreover, it exhibits the functional beauty unique to artificial materials and can give a sense of luxury as a product, so its industrial value is enormous.

<Example> Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Water glass (S i Oz = 35 to 38%, Na, ○-17 to
19%, Wako 1st class reagent) was added in the ratio shown in Table 1 and kneaded with a stirrer, and then 5 g of the kneaded powder was added to a press (Impertarp L/S, ESB-015-Q O1 Toyo Hydraulic Machinery). ), 500 kg/
It was pressure-molded using crA, and then heat-treated in a drying oven at a temperature of 150° C. for 10 hours. Table 1 shows the bulk density and crushing strength of the molded product obtained.

The molded body thus obtained was crushed in a mortar to form particles with an average particle size of 500μ, and then the unsaturated polyester resin (
Add 100 parts by weight to 100 parts by weight of Eborasoku G-22L (manufactured by Nippon Shokubai Kagaku), add 1.5% by weight of methyl ethyl ketone peroxide (based on the resin) as a hardening agent, and mix thoroughly with a stirrer. It was molded, hardened at 60° C. for 6 hours, and cooled to obtain a molded product of 10×10×1 cd. Table 1 shows the properties of the molded product obtained.

In addition, the method was the same except that aluminum hydroxide, which was prepared by pre-mixing 1% by weight of carbon blank (based on the aluminum hydroxide soft body) with the same aluminum hydroxide used in the above examples, was used in place of the raw material aluminum hydroxide in the above examples. A molded product was obtained by mixing with unsaturated polyester. The results are shown in Table 1 as Experiment Level 5. In addition, molded bodies were obtained by the same treatments as in Experiments 1 to 4 above except that the post-molding heat treatment was not performed, and a molded body was also obtained by mixing with unsaturated polyester. The results are shown in Table 1 as Experiment 8.

Furthermore, a molded body was obtained in the same manner except that aluminum hydroxide with an average secondary particle size of 1 μm (average primary particle size of 0.5 μm) was used in place of the raw material aluminum hydroxide used in Experiments 1 to 4 above. , and also mixed with unsaturated polyester to obtain a molded article.

Experiment with the results! 17 in Table 1.

In addition, in this example, the crushing strength was determined by universal tensile test i (TC
M-1000, Shinko iJ! (manufactured by Ishin Kogyo) at a weighted impression acceleration of 1 c+a/min.

Claims (2)

[Claims] (1) Coarse aluminum hydroxide for use as a filler and having an average secondary particle diameter of 100 μm or more, which is obtained by bonding aluminum hydroxide with an inorganic binder. (2) Aluminum hydroxide and an inorganic binder are mixed, formed to have an average particle size of 100 μm or more, and then heat treated.The average secondary particle size is 10 μm or more.
A method for producing coarse aluminum hydroxide for fillers with a size of 0 μm or more.