JP5265905B2 - Cubic boehmite - Google Patents

Description

The present invention relates to Bemai bets that can be used as fillers in the filling material such as synthetic resin, in particular, can increase the degree of filling of the object to be filling, and physical properties with product by the filling about the cubic Bemai bets possible to suppress the deterioration.

  Boehmite is used as a filler for filling materials such as flame retardants for synthetic resins, rubber, substrates, cosmetic brighteners, high-temperature catalyst carriers, paper coating fillers, paint pigments, etc. Used as a raw material for alumina. In particular, boehmite with a high decomposition temperature is suitable as a resin flame retardant for substrates that must withstand the soldering temperature, or as a flame retardant for industrial resin materials that have high melting heat during shearing and kneading. Therefore, it is necessary to increase the filling degree because the flame retardant effect is small compared to other flame retardants. Further, when the filling degree is increased, the flame retardancy is increased. However, since the physical properties of the filling material tend to be lowered, it is important to increase the filling degree without lowering the physical properties of the filling material.

Conventionally, boehmite has plate-like boehmite (see Patent Document 1), hexagonal plate-like boehmite (see Patent Document 2), and fine plate-like boehmite (see Patent Document 3) in various forms and needle-like boehmite (Patent Document). 4)). In addition to these boehmites, cubic boehmite is also known.
JP 20032641 A JP 2003-2642 A JP-A-5-279019 JP 2003-54941 A

  However, plate-like boehmite and needle-like boehmite are excellent in orientation because the aspect ratio (major axis / thickness) is larger than that of cubic boehmite, but they are bulky and have higher viscosity than cubic boehmite, so filling to be filled There was a problem that the degree could not be increased. On the other hand, even with cubic boehmite, the larger the particle size compared to the smaller the particle size, the smaller the specific surface area and the higher the degree of filling, so it is larger to increase the degree of filling of boehmite into the filling material. Cubic boehmite with a particle size is desirable. However, the conventional cubic boehmite has a major axis smaller than 1.3 μm, and larger cubic boehmite becomes a polycrystal and cannot be obtained as a single crystal. Moreover, when the filling degree of the boehmite to the filling material is increased as described above, there is a problem that the physical properties of the filling material are lowered.

The present invention has been made in view of the above, it is possible to increase the degree of filling of the with product such as a synthetic resin, and provides a cubic Bemai bets can suppress the deterioration of physical properties with product by the filling The task is to do.

The inventors of the present invention have repeatedly studied as a subject that it can be produced by controlling to a cubic boehmite having a major axis of 1.3 μm or more, and after producing boehmite when producing boehmite by hydrothermal synthesis using aluminum hydroxide as a raw material. The present invention was completed by paying attention to the sodium ion concentration contained in the reaction filtrate. That is, the present invention has a major axis of 1.3 to 3.5 μm, an aspect ratio (major axis / thickness) of 2.00 to 3.50, and a ratio of major axis to minor axis (major axis / minor axis) of 1. The gist is cubic boehmite characterized by being a single crystal having a minor axis to thickness ratio (minor axis / thickness) of 1.42 to 2.55.

  The cubic boehmite may be filled in a resin composition, particularly a substrate, a semiconductor package, or an industrial resin material. Here, the industrial resin material is a resin material that requires corrosion resistance, chemical resistance, workability (particularly cutting, bending, welding), and the like, for example, an industrial plate.

  Since the cubic boehmite of the present invention can increase the filling degree of the filling material such as a synthetic resin, the flame retardance of the filling material can be increased. In addition, the cubic boehmite of the present invention is excellent in practicality because it can suppress a decrease in physical properties of the filling material even when the filling degree of the filling material is increased.

  Although aluminum hydroxide used as a raw material can be used without any particular limitation, aluminum hydroxide produced by the Bayer method can be used. The particle size of aluminum hydroxide is generally proportional to the particle size of boehmite to be produced. However, the particle size of boehmite should be larger than the particle size of aluminum hydroxide due to temperature conditions during hydrothermal synthesis. Can also be made smaller. Usually, the particle size of the starting aluminum hydroxide is preferably 0.5 to 5 μm.

The cubic boehmite of the present invention has a major axis of 1.3 to 3.5 μm, an aspect ratio (major axis / thickness) of 2.00 to 3.50, and a ratio of major axis to minor axis (major axis / minor axis). Is 1.68 to 1.37, and the ratio of the minor axis to the thickness (minor axis / thickness) is 1.42 to 2.55. The major axis is preferably 1.5 to 3.2 [mu] m, more preferably 1.8 to 3.1 [mu] m, and the aspect ratio is preferably 2.00 to 3.15, and 2.00 in that the form of boehmite is closer to the cube. -2.50 is more preferable. For the same reason, the ratio of the minor axis to the thickness (minor axis / thickness) is preferably 1.42 to 2.15, more preferably 1.42 to 1.65. The major axis and the minor axis are diagonal lengths of the largest surface of boehmite. Therefore, in the case of a cube, the aspect ratio (major axis / thickness) is obtained as √2 (1.41) with the diagonal length as the major axis and the minor axis. Further, the ratio of the major axis to the minor axis (major axis / minor axis) is 1. Therefore, in comparison with these, the boehmite of the present invention has an aspect ratio (major axis / thickness) of 2.00 to 3.50 and a ratio of major axis to minor axis (major axis / minor axis) of 1.68 to 1.37. Therefore, it becomes a shape close to a cube. In the case of a cube, the ratio of the minor axis to the thickness (minor axis / thickness) is obtained by using the diagonal length as the major axis and the minor axis, which is √2 (1.41) as described above.
Therefore, the boehmite of the present invention has a minor axis / thickness ratio (minor axis / thickness) of 1.42 to 2.55, and thus has a shape close to a cube from the point of the minor axis. In addition, the numerical value which prescribes | regulates said cubic boehmite is prescribed | regulated about the single crystal of boehmite.

  Subsequently, the manufacturing method of the cubic boehmite of this invention is demonstrated. Since aluminum hydroxide produced by the Bayer process uses sodium hydroxide in the production process, the produced aluminum hydroxide contains sodium. Cubic boehmite has a water ratio such that the sodium ion concentration contained in the reaction filtrate after filtration of the reaction liquid after boehmite is generated by hydrothermal synthesis is within the range of 0.001 to 0.100 mass%. Can be manufactured in advance. If the sodium ion concentration is less than 0.001% by mass, the water ratio is large and the amount of water is large, so that the energy required for maintaining the autoclave at a predetermined reaction temperature increases, resulting in poor economic efficiency. Further, as the sodium ion concentration becomes higher than 0.100% by mass, the form of boehmite becomes closer to a plate shape, and it becomes difficult to obtain cubic boehmite. In consideration of economic efficiency and boehmite in a form closer to a cube, the sodium ion concentration is preferably 0.001 to 0.070 mass%, more preferably 0.001 to 0.030 mass%. . Cubic boehmite is prepared by adding water in a preset water ratio to aluminum hydroxide and mixing well. After both are put in an autoclave, pressurize and warm, and hydrothermal synthesis is carried out under standing or stirring. Then, it can manufacture by filtering, washing | cleaning, drying, etc. of the boehmite of the obtained reaction product. The water ratio refers to the ratio of the mass of water to the mass of the starting aluminum hydroxide (the mass of water / the mass of aluminum hydroxide). The water ratio 5 is, for example, when 100 g of aluminum hydroxide is used, Become.

  The amount of sodium contained in commercially available aluminum hydroxide is shown as product information. Based on this data, the sodium ion concentration contained in the reaction filtrate should be preset to a water ratio within the above range. Easy. Of course, the amount of sodium contained in aluminum hydroxide can be determined for each lot, and the water ratio can be set based on this data.

  The temperature in the autoclave when hydrothermal synthesis is performed is 150 to 300 ° C, preferably 160 to 235 ° C, more preferably 170 to 215 ° C. If this temperature is less than 150 ° C., it is difficult to obtain boehmite as a reaction product. Further, if the temperature exceeds 300 ° C., the spontaneously generated pressure in the autoclave exceeds 8665 kPa, which increases the cost in terms of equipment and may include alumina. Moreover, the naturally generated pressure at the time of hydrothermal synthesis is 378 to 8665 kPa, preferably 522 to 3028 kPa, more preferably 699 to 2045 kPa, corresponding to the temperature in the autoclave.

  The reaction time is 4 to 24 hours, preferably 7 to 19 hours. If it is less than 4 hours, unreacted aluminum hydroxide may remain, and if it is 24 hours, the reaction is completed.

  Cubic boehmite can be filled in a synthetic resin, rubber, electric wire or the like as a flame retardant, and can be filled in cosmetics or paints as a brightening agent. Since cubic boehmite can increase the filling degree of the filling material, it is useful as a flame retardant for resin compositions that require high flame retardancy, such as substrates, semiconductor packages, or industrial resin materials.

  As the resin filled with the cubic boehmite of the present invention, polyethylene, polypropylene, polyvinyl chloride, polyamide, ABS resin, polyester, polycarbonate, polyacetal, polyphenylene sulfide, polyphenylene ether, polysulfone, polyethersulfone, polyetherimide, poly Examples include ether ether ketone, epoxy resin, silicone resin, phenol resin, alkyd resin, unsaturated polyester, diallyl phthalate, polystyrene, fluororesin, saturated polyester, urea resin, melamine-containing resin, polyurethane and the like. Examples of the rubber filled with the cubic boehmite of the present invention include silicone rubber, acrylic rubber, butyl rubber, ethylene propylene rubber, and olefin elastomer.

  EXAMPLES Next, although an Example is given and this invention is demonstrated, this invention is not limited to a following example.

[Example 1] (Production of cubic boehmite)
Boehmite was produced by hydrothermal synthesis using aluminum hydroxide (manufactured by Nippon Light Metal Co., Ltd., BF-013) as a raw material. The boehmite of Test Examples 1 to 6 shown in the table is 100 g of water (water ratio 1), 200 g (water ratio 2), 300 g (water ratio 3), 500 g (100 g of water) corresponding to 100 g of aluminum hydroxide and each water ratio. The water ratio 5), 1000 g (water ratio 10), and 10000 g (water ratio 100) were mixed well, then placed in an autoclave and hydrothermally treated at 180 ° C. for 12 hours under a naturally generated pressure (about 900 kPa). Could be dehydrated and dried.

The boehmite obtained in each test example was observed with a scanning electron microscope (manufactured by Hitachi, Ltd., S-2400), and the average value was obtained by measuring 25 points each for the major axis, minor axis, and thickness of boehmite. It was.
The major axis and minor axis were measured for diagonal length. The results are shown in Table 1.

  The sodium ion concentration contained in the reaction filtrate after the formation of boehmite in each test example was measured using an ion analyzer (IA-300, manufactured by Toa DKK Corporation). Table 2 shows the sodium ion concentration in the reaction filtrate (in the table, the sodium ion concentration is expressed as Na ion concentration) (% by mass). Also, the aspect ratio (major axis / thickness) obtained from the major axis, minor axis, and thickness in Table 1, the ratio of major axis to minor axis (major axis / minor axis), and the ratio of minor axis to thickness (minor axis / thickness). )showed that.

  From the aspect ratio (major axis / thickness), the ratio of major axis to minor axis (major axis / minor axis), and the ratio of minor axis to thickness (minor axis / thickness) in Table 2, Test Example 1 and Test Example 2 are plates. The test examples 3 to 6 were boehmite close to a cube (cubic boehmite). Moreover, although the photographic image by the scanning electron microscope of the boehmite obtained in Test Example 3 was shown in FIG. 1, it turns out that Test Example 3 is cubic boehmite from now on.

[Example 2] (Relationship between sodium ion concentration contained in reaction filtrate after formation of boehmite and aspect ratio (major axis / thickness) of boehmite, ratio of major axis to minor axis of boehmite (major axis / minor axis) And the ratio of minor axis to thickness (minor axis / thickness))
Using the semilogarithmic graph, a graph in which the horizontal axis is the sodium ion concentration (mass%) contained in the reaction filtrate, the vertical axis is the aspect ratio, and the sodium ion concentration and aspect ratio of Test Example 1 to Test Example 6 are plotted. It was prepared (see FIG. 2, in which the sodium ion concentration is expressed as Na ion concentration). From FIG. 2, it was found that there is a correlation between the sodium ion concentration and the aspect ratio, and the aspect ratio decreases with decreasing sodium ion concentration, and the shape becomes close to a cube. The horizontal axis is the sodium ion concentration (mass%) contained in the reaction filtrate, the vertical axis is the ratio of the major axis to the minor axis (major axis / minor axis), and the sodium ion concentration and major axis of Test Example 1 to Test Example 6 A graph plotting the ratio of the major axis and the minor axis (major axis / minor axis) was made using a semi-logarithmic graph (see FIG. 3, where the sodium ion concentration is expressed as the Na ion concentration). From FIG. 3, there is a correlation between the sodium ion concentration and the ratio of the major axis to the minor axis (major axis / minor axis), and the ratio of the major axis to the minor axis (major axis / minor axis) decreases with decreasing sodium ion concentration. Although it increases, the value does not exceed 2 and it has been found that the form of boehmite is close to a cube. Furthermore, the sodium ion concentration (mass%) contained in the reaction filtrate on the horizontal axis and the ratio of the minor axis to the thickness (minor axis / thickness) on the vertical axis, the sodium ion concentrations of Test Example 1 to Test Example 6 A graph plotting the ratio of the minor axis to the thickness (minor axis / thickness) was created using a semi-logarithmic graph (see FIG. 4, in which the sodium ion concentration is expressed as the Na ion concentration). From FIG. 4, there is a correlation between the sodium ion concentration and the ratio of the minor axis to the thickness (minor axis / thickness), and the ratio of the minor axis to the thickness (minor axis) as the sodium ion concentration decreases. (Thickness / thickness) also decreased, and it was found that the form of boehmite was close to a cube in terms of the minor axis and thickness (minor axis / thickness). From these results, when producing boehmite using aluminum hydroxide as a raw material, hydrothermal synthesis is performed by setting the water ratio in advance so that the sodium ion concentration contained in the reaction filtrate after the formation of boehmite is within a certain range. As a result, it has been clarified that it can be controlled to be cubic boehmite having a major axis of 1.3 μm or more.

[Example 3] (Examination of filling property of cubic boehmite)
The screw current value used as a measure of filling property when kneading resin and filler boehmite was measured with a twin-screw kneading extruder (KZW15TW-45MG-NH (-700), manufactured by Technobel Co., Ltd.). The screw current value increases when a load is applied to the twin-screw kneading extruder. Therefore, the higher the screw current value, the lower the filling degree of the resin. The cubic boehmite shown in Test Example 3 of the present invention is filled in each part by mass shown in Table 3 with respect to 100 parts by mass of the polypropylene resin (J-5051HP manufactured by Prime Polymer Co., Ltd., hereinafter referred to as “PP”). Then, the mixture was kneaded with a biaxial kneading extruder, and the screw current value displayed on the biaxial kneading extruder was measured. Further, as a control, plate-like boehmite having an aspect ratio of 15 to 25 and plate-like boehmite having an aspect ratio of 5 to 10 were filled in PP, and the screw current value was measured in the same manner. The results are shown in Table 3.

  From Table 3, it was difficult to fill 150 parts by mass of plate-like boehmite having an aspect ratio of 15 to 25 with respect to 100 parts by mass of PP. The plate boehmite having an aspect ratio of 5 to 10 had a limit of 225 parts by mass with respect to 100 parts by mass of PP. On the other hand, the cubic boehmite of the present invention was able to fill 275 parts by mass with respect to 100 parts by mass of PP. From the above results, it has been clarified that the cubic boehmite of the present invention can increase the filling degree of the filling material.

[Example 4] (Examination of physical properties of filling material filled with cubic boehmite)
100 parts by mass of cubic boehmite shown in Test Example 3 of the present invention, plate boehmite having a control aspect ratio of 15 to 25, and plate boehmite having an aspect ratio of 5 to 10 with respect to 100 parts by mass of PP to be filled. Each was kneaded using a biaxial kneading extruder, and an Izod impact strength test was conducted in accordance with JIS K7110 (plastic-Izod impact strength test method, notch). The results are shown in FIG.

  FIG. 5 shows that the PP with the cubic boehmite of the present invention has a lower Izod impact strength than the PP with no boehmite filled, but the control boehmite with an aspect ratio of 15-25 and a plate with an aspect ratio of 5-10. As compared with PP filled with each of the boehmite, the decrease was obviously small. From the above results, it has been found that the cubic boehmite of the present invention is more practical than the plate boehmite because the decrease in Izod impact strength is suppressed even when the filling degree of the filling material is increased.

  In addition, 100 mass parts each of the cubic boehmite shown in Test Example 3 of the present invention, the plate boehmite having an aspect ratio of 15 to 25, and the plate boehmite having an aspect ratio of 5 to 10 with respect to 100 parts by mass of the PP to be filled. Each part was kneaded using a biaxial kneading extruder, and a tensile test and a bending test were performed in accordance with JISK7113 (plastic tensile test method) and JISK7203 (hard plastic bending test method), respectively. The results are shown in FIG. 6 and FIG.

  6 and 7, the cubic boehmite of the present invention has less decrease in tensile strain and bending strain than the control plate boehmite, and even when the filling degree is increased, the decrease in flexibility of the filling material is suppressed. It turned out to be highly practical.

It is a photographic image by the scanning electron microscope of the cubic boehmite of the present invention. It is a graph which shows the relationship between the sodium ion concentration (mass%) contained in the reaction filtrate after the production | generation of boehmite, and an aspect-ratio. It is a graph which shows the relationship between the sodium ion concentration (mass%) contained in the reaction filtrate after the production | generation of boehmite, and the ratio of a major axis and a minor axis (major axis / minor axis). It is a graph which shows the relationship between the sodium ion concentration (mass%) contained in the reaction filtrate after the production | generation of boehmite, and the ratio of a short diameter and thickness (short diameter / thickness). It is a graph which shows the result of an Izod impact strength test. It is a graph which shows the result of a tension test. It is a graph which shows the result of a bending test.

Claims (3)

The major axis is 1.3 to 3.5 μm, the aspect ratio (major axis / thickness) is 2.00 to 3.50, and the ratio of major axis to minor axis (major axis / minor axis) is 1.68 to 1.37. Cubic boehmite characterized by being a single crystal having a minor axis / thickness ratio (minor axis / thickness) of 1.42 to 2.55.   A resin composition comprising the cubic boehmite according to claim 1.   The resin composition according to claim 2, wherein the resin composition is a substrate, a semiconductor package, or an industrial resin material.

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