JPH09176367A - Aluminum hydroxide for resin filling and resin composition using the same - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a resin molded product which can be uniformly dispersed in a resin at the time of mixing, gives a sufficient compound hardness at the time of pressing, and has excellent mechanical strength and appearance. The purpose is to develop resin-filled aluminum hydroxide suitable for molding. A mean particle diameter of 5 m to 30 m, BET specific surface function 0.5m ² /g~4.5m ² / g, a shape factor 2-10 by X-ray [gibbsite (002) plane / (110)
And the aluminum hydroxide powder having a whiteness of 93 or more are used as a resin filler for BMC molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-filling aluminum hydroxide, and more particularly, when applied to a resin, it has good moldability, and particularly BMC (Bulk Moul).
aluminum compound for resin filling capable of providing a resin composition which gives a compound viscosity behavior suitable for molding, has an excellent molding cycle property at the time of curing, and has excellent mechanical strength and appearance of the molded body after curing. Is.

[0002]

2. Description of the Related Art Conventionally, artificial marble obtained by filling a resin with an inorganic filler and curing it has been widely used for applications such as kitchen counters and bathtubs. Among these inorganic fillers, aluminum hydroxide has physical properties such as transparency, chemical stability, and flame retardancy, and its hardness is lower than that of silica, etc., so that the stirring device used for mixing with a mold or resin can be used. It is very useful as a filler for artificial marble because it is less worn and is inexpensive. Further, a highly white substance containing less impurities such as organic substances is less excellent in coloring the molded product, and is particularly excellent as a filler for an artificial marble because it gives a high-quality artificial marble.

However, when using commercially available aluminum hydroxide as a filler, there has been a problem in that sufficient compound hardness cannot be obtained in BMC molding. Therefore, compound hardness is maintained (fill viscosity is increased)
As a method, aluminum hydroxide having a small particle size is used, a filling amount is increased, a thickener or the like is added, and the like. However, when increasing the resin filling viscosity by these methods, a compound having sufficient hardness can be obtained, but since the viscosity at the time of mixing is high, aluminum hydroxide cannot be uniformly dispersed in the resin, and therefore the molding Problems such as insufficient mechanical strength of the body and adverse effects on the appearance and mechanical strength of the molded body such as inclusion of air bubbles and formation of cavities during pressing occur.

[0004]

In view of such circumstances, in view of the above circumstances,
From the results of many experiments, the present inventors have found that a resin composition suitable for BMC application has sufficient compound hardness such that cavities do not occur at the time of pressing (that is, at low shear rate), and when mixed. At a high shear rate (that is, at a high shear rate), a low viscosity that allows aluminum hydroxide powder to be uniformly mixed is required, so that thixotropy within a certain range is required, and a filler suitable for BMC applications. as,
A resin composition prepared by filling 100 parts by weight of a vinyl ester resin having a viscosity of 8 to 10 poises at 25 ° C. with 200 parts by weight of aluminum hydroxide was kept at 25 ° C. and was measured with a DVU-B type viscometer. When using 7 rotors and the viscosity at 5 rpm (at low shear speed) is 500 poises to 2000 poises, it should have sufficient compound hardness so that cavities do not occur during pressing. Two
A value (5 rpm viscosity / 20 rpm viscosity: this is referred to as thixotropy index) obtained by dividing the above-mentioned measured viscosity value at 5 rpm by a value measured at 0 rpm (at high shear rate) is in the range of 1 to 3. In this case, aluminum hydroxide was uniformly dispersed in the resin, and it was found that a molded product having no bubbles, a beautiful appearance, and excellent mechanical strength was obtained, and many aluminum hydroxide powders were used as an index. As a result of conducting experimentation by combining physical properties as variables, when aluminum hydroxide having a certain specific range of average particle diameter, BET specific surface area, X-ray shape factor and high whiteness is used, all the above problems are solved. Resin composition capable of providing a resin-filled aluminum hydroxide suitable for a BMC application, and providing a molded article having excellent physical properties when using this as a filler This has led to the completion of the present invention found that can be obtained.

[0005]

Means for Solving the Problems That is, the present invention provides an average particle size of 5 μm to 30 μm and a BET specific surface area of 0.5 m ² /
g-4.5 m ² / g, X-ray shape factor 2 to 10 [gibbsite (002) plane / (110) plane peak intensity ratio], and whiteness of 93 or more, resin used for BMC molding To provide aluminum hydroxide for filling.

The present invention further provides a resin composition obtained by filling 50 to 400 parts by weight of the above aluminum hydroxide for resin filling with 100 parts by weight of an unsaturated polyester resin, a vinyl ester resin or a methacrylate resin. .

[0007]

The present invention will be described in more detail below. As the aluminum hydroxide powder used in the present invention, an alumina hydrate represented by the general formula Al ₂ O ₃ .nH ₂ O (where n = 1 to 3), generally alumina trihydrate is used. .

The average particle diameter of the aluminum hydroxide powder used in the present invention is 5 μm to 30 μm, preferably 8 μm to 2
The range is 0 μm. If it is less than 5 μm, the viscosity at the time of resin filling becomes too high, uniform dispersion becomes difficult, and there is a problem that the gelling time is delayed, and the amount of hydroxylation that can give the texture of the artificial marble to the resin is provided. Filling with aluminum becomes difficult. On the other hand, when it is larger than 30 μm, not only the surface gloss of the finally obtained resin composition molded article is deteriorated but also the mechanical strength is lowered, but also the gravity precipitation of the aluminum hydroxide powder may occur depending on the curing conditions. In some cases, a molded body in which the filling material is unevenly dispersed may be obtained. Here, the average particle size used in the present invention refers to a value measured by a particle size distribution measuring device by a laser diffraction method.

Further, BET specific surface area of the aluminum hydroxide powder used in the present invention is 0.5m ² /g~4.5m ² /
g, preferably in the range of 1.5m ² /g~3.0m ² / g. If the BET specific surface area of the powder is less than 0.5 m ² / g, the amount of physically adsorbed water on the surface of aluminum hydroxide is small, and sufficient compound hardness cannot be obtained, making press molding difficult. On the other hand, if it is more than 4.5 m ² / g, the amount of physically adsorbed water on the surface of the aluminum hydroxide powder will be too much, and the gelling time (the time until the compound is cured to form a molded product) will be delayed, and in some cases curing failure may occur. It may occur, and the resin filling viscosity also increases. Here, the BET specific surface area used in the present invention means a value measured by a nitrogen adsorption method.

Further, the X-ray shape factor of the aluminum hydroxide powder used in the present invention is in the range of 2 to 10, preferably 4 to 8. If this value is smaller than 2, the thixotropy required for BMC molding, that is, the viscosity behavior that the viscosity during mixing is low and the viscosity during pressing is high cannot be obtained. On the contrary, if this value is larger than 10, thixotropy occurs but the viscosity at the time of substantial mixing becomes high, making it difficult to uniformly disperse the powder in the resin,
Further, the viscosity at the time of press molding may be too high, and the molded body may have cavities. The X-ray shape factor used in the present invention means aluminum hydroxide powder at a voltage of 50 kV and 40 mA.
The value obtained by dividing the peak intensity of the gibbsite (002) plane by the X-ray diffraction measurement with the Cu-Kα ray generated under the condition of No. 1 by the peak intensity of the gibbsite (110) plane, the cleavage plane by crushing It is a value that indicates how much it appears.

The whiteness of the aluminum hydroxide powder used in the present invention is 93 or more, preferably 95 or more.
If this value is less than 93, the molded body is colored and a high-quality appearance of artificial marble cannot be obtained. Here, the whiteness in the present invention refers to the Hunter whiteness of the powder. Aluminum hydroxide having each of these physical properties independently has existed in the past, but the present inventors, when satisfying all of these physical properties at the same time, have excellent workability and physical properties as a resin filler for BMC molding. It has been found that a resin composition having the above can be obtained. Even if the average particle diameter and the BET specific surface area are within this range, if the X-ray shape factor is out of this range, it is suitable for BMC molding. There is a problem that the thixotropic property cannot be obtained.

The method for obtaining the aluminum hydroxide powder having such physical properties is not particularly limited, but an aluminum hydroxide raw material having a high whiteness and a sharp particle size distribution, for example, an average particle diameter of about 20 to 120 μm and a BET ratio. An aluminum hydroxide powder having a surface area of 0.05 to 0.5 m ² / g, a D _90% / D _10% ratio of 3.5 or less, more preferably 3 or less and a whiteness of 85 or more was used as a raw material. It can be obtained by pulverizing with a volume pulverizer such as a vibration mill.

In the practice of the present invention, aluminum hydroxide is treated with a surface treating agent such as a silane coupling agent on the surface of aluminum hydroxide for the purpose of improving the mechanical strength or boiling resistance of the obtained molded product. It can also be used.

The silane coupling agent is not particularly limited, but examples thereof include methacrylic silane, acrylic silane, vinyl silane, epoxy silane, and amino silane. Further, these silane coupling agents may be used in combination with silicate or the like, and can be used properly according to the purpose. The amount of these surface-treating agents added is naturally determined from the desired physical properties and the balance of price, but it is usually used in the range of about 0.1 to 3 parts by weight per 100 parts by weight of the aluminum hydroxide powder. It is common. The addition method of these surface treatment agents is not particularly limited, but a Henschel mixer,
A method of adding aluminum hydroxide powder while stirring with a blender or the like is general, and these surface treatment agents may be added to the crusher at the same time as aluminum hydroxide, and the crushing and the treatment may be performed at the same time.

The resin to be blended with the aluminum hydroxide of the present invention is not particularly limited as long as it is a resin used for BMC molding, but for artificial marble, for example, unsaturated polyester resin, vinyl ester resin, methyl methacrylate. Resin etc. are mentioned. The addition amount (filling amount) of the aluminum hydroxide of the present invention into the resin may be within a known range. For example, when used for artificial marble, it is about 50 parts by weight to about 400 parts by weight with respect to 100 parts by weight of the resin. Parts, preferably in the range of about 150 parts by weight to about 300 parts by weight. If the amount of aluminum hydroxide added to the resin is small, it is difficult to obtain the texture of the artificial marble, and since the amount of resin is relatively large, the cost becomes high, which is not preferable. On the contrary, when the filling amount of aluminum hydroxide is too large, the dispersibility of the aluminum hydroxide powder in the resin is deteriorated and the mechanical strength of the obtained molded product is lowered.

[0016]

As described above in detail, the aluminum hydroxide powder of the present invention is filled in a considerably large amount with a resin such as unsaturated polyester resin, vinyl ester or methacrylate to obtain a molded article such as artificial marble. Even in such a case, it can be uniformly dispersed in the resin at the time of mixing, gives sufficient compound hardness at the time of pressing, and the obtained resin molded product also has excellent mechanical strength and appearance.
It is extremely effective as a resin-filled aluminum hydroxide powder for C molding, and its industrial value is enormous.

[0017]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In this Example, the particle size distribution was measured by the following method. Particle size distribution: 0.5 g of aluminum hydroxide powder was added to 60 ml of 0.2% sodium hexametaphosphate aqueous solution, and 1
The sample solution obtained by ultrasonically dispersing for 0 minutes was used as a laser diffraction type microtrack particle size analyzer model 7997-10-S.
In RA, cumulative 50% particle size and cumulative 90
Measure percent particle size and cumulative 10 percent particle size,
Calculated.

Example 1 BET specific surface area of 0.13 m with whiteness of 98^Two/ G, average grain
Child diameter 62.1 μm, D _90%/ D_Ten%Grains with a ratio of 3.2
Contains 300g of aluminum hydroxide with a sharp degree distribution
2 liter alumina pot (aluminum with a diameter of 8 mm
2.9 kg of balls made by Na are filled in) and the amplitude is 3 mm.
Vibratory mill grinding was performed for 0 minutes. The resulting hydroxide
Luminium has an average particle size of 9.8 μm and a BET specific surface area.
1.58m ^Two/ G, X-ray shape factor 4.0, whiteness 97
there were. 200 parts by weight of the above aluminum hydroxide is added at 25 ° C.
Vinyl ester resin with a viscosity of 8.5 poise (commercial
Product name XP-675, manufactured by Takeda Pharmaceutical Co., Ltd.) 100
The parts were filled and mixed well. At 25 ° C of this composition
Measure with a DVU-B type viscometer (using a No. 7 rotor)
When determined, the viscosity at 5 rpm is 1200 poise.
The thixotropic index was 1.5. This composition
The cured product has a transparent appearance and little coloration.
It was good.

Example 2 Vibration milling was performed under the same conditions as in Example 1 except that the grinding raw material used in Example 1 was used and the grinding time was changed to 60 minutes. The aluminum hydroxide obtained as a result had an average particle diameter of 7.1 μm, a BET specific surface area of 2.63 m ² / g, an X-ray shape factor of 6.8, and a whiteness of 96. Using this, a resin composition was prepared in the same manner as in Example 1 and the viscosity was measured. As a result, the viscosity at 5 rpm was 1640 poise and the thixotropy index was 2.0. The appearance of the molded product obtained by curing this composition was good with little transparency and little coloring.

Example 3 A BET specific surface area of 0.14 m ² /
g, average particle diameter 88.0 μm, D _90% / D _10% ratio of 2.
Vibration milling was performed under the same conditions as in Example 1 except that aluminum hydroxide having a sharp particle size distribution of 7 was used. The resulting aluminum hydroxide had an average particle diameter of 12.0 μm, a BET specific surface area of 1.70 m ² / g, and an X
The linear shape factor was 2.3 and the whiteness was 96. Using this, a resin composition was prepared in the same manner as in Example 1 and the viscosity was measured. As a result, the viscosity at 5 rpm was 850 poise and the thixotropy index was 1.3. The appearance of the molded product obtained by curing this composition was good with little transparency and little coloring.

Example 4 Vibration milling was carried out under the same conditions as in Example 3 except that the grinding raw material used in Example 3 was used and the grinding time was changed to 60 minutes. The resulting aluminum hydroxide had an average particle size of 9.0 μm, a BET specific surface area of 2.44 m ² / g, an X-ray shape factor of 8.0, and a whiteness of 95. Using this, a resin composition was prepared in the same manner as in Example 1 and the viscosity was measured. As a result, the viscosity at 5 rpm was 1850 poise and the thixotropy index was 2.3. The appearance of the molded product obtained by curing this resin composition was good with little transparency and little coloring.

Comparative Example 1 BET specific surface area of 0.15 m ² /
g, average particle size 74.4 μm, D _90% / D _10% ratio of 4.
Example 1 except that aluminum hydroxide of 0 was used
Vibration milling was performed under the same conditions as above. The aluminum hydroxide obtained as a result had an average particle size of 35.2 μm, a BET specific surface area of 1.23 m ² / g, an X-ray shape factor of 3.5, and a whiteness of 96. Using this, a resin composition was prepared in the same manner as in Example 1 and the viscosity was measured. As a result, 5 rpm
Viscosity is 460 poise and thixotropic index is 1.3.
Met.

Comparative Example 2 Vibration milling was carried out under the same conditions as in Comparative Example 1 except that the grinding raw material used in Comparative Example 1 was used and the grinding time was changed to 60 minutes. The aluminum hydroxide obtained as a result had an average particle size of 13.9 μm, a BET specific surface area of 2.42 m ² / g, an X-ray shape factor of 15.3, and a whiteness of 95. Using this, a resin composition was prepared in the same manner as in Example 1 and the viscosity was measured. As a result, the viscosity at 5 rpm was 2500 poise and the thixotropy index was 3.5.

Comparative Example 3 Vibration milling was carried out under the same conditions as in Example 1 except that the grinding raw material used in Example 1 was used and the grinding time was changed to 10 minutes. The aluminum hydroxide obtained as a result had an average particle size of 32.7 μm, a BET specific surface area of 1.00 m ² / g, an X-ray shape factor of 1.7, and a whiteness of 98. Using this, a resin composition was prepared in the same manner as in Example 1 and the viscosity was measured. As a result, the viscosity at 5 rpm was 450 poise and the thixotropy index was 1.2.

Comparative Example 4 The pulverization raw material used in Example 1 was used, and the pulverization time was 120.
Vibration milling was performed under the same conditions as in Example 1 except that the amount was changed to minutes. The aluminum hydroxide obtained as a result had an average particle size of 5.3 μm, a BET specific surface area of 4.85 m ² / g, an X-ray shape factor of 9.4, and a whiteness of 94. Using this, a resin composition was prepared in the same manner as in Example 1 and the viscosity was measured. As a result, the viscosity at 5 rpm was 3100 poise, and the thixotropy index was 2.9.

Comparative Example 5 BET specific surface area 0.21 m ² /
g, average particle size 67.1 μm, D _90% / D _10% ratio of 3.
Example 1 except that aluminum hydroxide which is 3 is used
Vibration milling was performed under the same conditions as above. The resulting aluminum hydroxide has an average particle size of 11.0 μm, BET
The specific surface area was 1.32 m ² / g, the X-ray shape factor was 3.5, and the whiteness was 89. Using this, a resin composition was prepared in the same manner as in Example 1 and the viscosity was measured. As a result, 5 rp
The viscosity at m was 1030 poise and the thixotropy index was 1.4. The molded product obtained by curing this resin composition had a transparent appearance but was colored yellow, which was not preferable as the color tone of artificial marble.

Claims (2)

[Claims] 1. A mean particle size 5 m to 30 m, BET specific surface area 0.5m ² /g~4.5m ² / g, a shape factor 2-10 by X-ray [gibbsite (002) plane / (110)
Surface intensity ratio] and a whiteness of 93 or more, the resin-filled aluminum hydroxide used for BMC molding. 2. The resin-filling aluminum hydroxide according to claim 1 is added in an amount of 50 to 100 parts by weight of an unsaturated polyester resin, a vinyl ester resin or a methacrylate resin.
A resin composition filled with 400 parts by weight.