JP3303374B2 - Gibbsite type aluminum hydroxide for resin filling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gibbsite type aluminum hydroxide for resin filling. More specifically, a gibbsite-type hydroxide for resin filling with excellent heat resistance that reduces swelling and cracking of the resin caused by detachment of water of crystallization during kneading with a resin, processing, and further, when using a processed product. It concerns aluminum.

[0002]

2. Description of the Related Art In recent years, as electronic components have become higher in performance and higher in density, there has been a demand for flame-retardant peripheral resin materials (insulating materials, wiring boards, packages, etc.) to be used. In response to this demand, various additive-type flame retardants such as phosphate ester type, halogen type, antimony oxide, and metal hydroxide have been developed and put into practical use. Among them, inorganic hydroxides such as aluminum hydroxide and magnesium hydroxide exhibit a flame-retardant effect by releasing crystallization water when heated, and thus are widely used as excellent flame retardants without generation of toxic gas. . At present, aluminum hydroxide filled as a flame retardant generally contains gibbsite-type crystals (Al
₂ O ₃ .3H ₂ O). Gibbsite-type aluminum hydroxide is relatively inexpensive and has about 35% by weight of water of crystallization. With heating, it is usually dehydrated at about 200 to about 300 ° C. to decompose into intermediate alumina and absorb a large amount of heat. Therefore, it is said to exhibit excellent properties as a flame retardant. However, when gibbsite-type aluminum hydroxide is actually filled in a resin and applied to an electronic substrate, it is usually exposed to a solder melting temperature of about 260 ° C. in a soldering step. For this reason, the gibbsite-type aluminum hydroxide filled in the substrate starts to thermally decompose, and a part of the gibbsite-type aluminum hydroxide (Al ₂ O)
_In order to dislocate to 3.H ₂ O), a part of the crystallization water is released, causing swelling and cracking of the substrate.

[0003] Such a phenomenon is caused not only in the field of electronic materials, but also in the case of using a gibbsite type aluminum hydroxide as a flame retardant in a thermoplastic resin such as polyethylene or polypropylene to use as a wall covering material, an interior material such as an automobile or a wire covering material. In applications, when the processing temperature is high, a part of the crystallization water is released during processing in the same manner as above, and the resin swells and the molded product surface becomes uneven, reducing the commercial value. Then the problem arises.

In order to suppress the initial thermal decomposition of aluminum hydroxide, JP-A-59-204632 discloses a resin composition using gibbsite type aluminum hydroxide having a total Na ₂ O concentration of 0.1% by weight or less. Has been proposed. Further, instead of gibbsite-type aluminum hydroxide, boehmite-type aluminum hydroxide (JP-A-62-71643)
No.) or a method using magnesium hydroxide (Japanese Unexamined Patent Publication No.
128038 to 63-128044), a method of filling aluminum hydroxide which has been subjected to a partial boehmite treatment (Japanese Patent Application Laid-Open Nos. 61-143444 and 62-5902).
No. 1), a technique for suppressing the initial thermal decomposition and improving the solder heat resistance is already known. In recent years, it has been recently considered that the cause of the decrease in heat resistance is due to the pulverization of aluminum hydroxide obtained by crystallization, and aluminum hydroxide having a desired particle diameter (primary particle diameter) is precipitated from the beginning, and this is substantially reduced. (Japanese Patent Laid-Open Publication No. Hei 3-
8715, JP-A-3-28121, JP-A-4-2939
1 etc.).

[0005] In the above-mentioned prior art, when the content Na ₂ 0 concentration was filled with 0.1 wt% or less of the gibbsite type aluminum hydroxide, an improvement in heat resistance is seen yet sufficiently satisfy consumers In addition, boehmite-type aluminum hydroxide and magnesium hydroxide have a crystallization water per atom of one-third and two-thirds, respectively, as compared with gibbsite-type aluminum hydroxide. In addition, the amount of heat absorbed and the amount of water of crystallization released during thermal decomposition are small, and the effect as a flame retardant is inferior. Further, boehmite-type aluminum hydroxide and partially boehmite-formed gibbsite-type aluminum hydroxide increase the cost because the gibbsite-type aluminum hydroxide is produced by hydrothermal treatment in an autoclave or the like. Further, there is a problem that sufficient heat resistance cannot be obtained by a method of precipitating aluminum hydroxide having a desired particle size (primary particle size) from the beginning.

[0006]

Under such circumstances, the present inventors have found that although the gibbsite type aluminum hydroxide has a large endothermic amount, it has little dislocation to boehmite in the initial stage of thermal decomposition, so-called high heat resistance. As a result of intensive studies to find gibbsite-type aluminum hydroxide for resin filling, the present invention has been completed.

[0007]

SUMMARY OF THE INVENTION Namely, the present invention provides (1) a spherical approximation specific surface area B _s which is calculated based on the particle size distribution measured by sedimentation balance method, BET specific surface area was measured by N ₂ adsorption method B _m Is 2 ≦ B _m / B _s , (2) the content of Na is 0.1% by weight or less in terms of Na ₂ O, and (3) the particle size distribution by sedimentation balance method is 4μ ≦ D ₅₀ ≦ Filling with thermosetting resin characterized in that 10 μD ₉₀ <D ₅₀ +10 μ (where D ₅₀ is the central particle diameter, and D ₉₀ is the particle diameter which becomes 90% by weight accumulation from the fine particle portion). To provide gibbsite-type aluminum hydroxide for use.

[0008] The present invention provides (1) a spherical approximation specific surface area B _s which is calculated based on the particle size distribution measured by sedimentation balance method, N ₂ ratio 2 ≦ B of BET specific surface area B _m as measured by adsorption _m / B _s , (2) the content of Na concentration is 0.1% by weight or less in terms of Na ₂ O, and (3) the particle size distribution by sedimentation balance method is D ₅₀ ≦ 4 μ D ₉₀ <D ₅₀ +4 μ (Wherein, D ₅₀ represents a central particle diameter, and D ₉₀ represents a particle diameter of 90% by weight accumulation from a fine particle portion). The present invention provides a gibbsite-type aluminum hydroxide for filling a thermoplastic resin. Things.

Hereinafter, the present invention will be described in more detail. Aluminum hydroxide of the present invention is a spherical approximation specific surface area B _s which is calculated on the basis of the particle size distribution measured by sedimentation balance method, a ratio of BET specific surface area B _m as measured by N ₂ adsorption method is 2 or more Required. The ratio of B _m / B _s is an index indicating the disorder of the crystal of aluminum hydroxide. If B _m / B _s is less than 2, the effect of the disorder on the crystal surface is weak, or the effect of suppressing the initial thermal decomposition. Is small.

The concentration of Na in aluminum hydroxide is 0.1% by weight or less in terms of Na ₂ O, usually 0.001%.
Wt% to 0.1 wt%, preferably 0.001 wt% to
It must be 0.05% by weight. For example if the Na concentration in the aluminum hydroxide exceeds the range B _m
/ Not seen the effect of improving the heat resistance and desired even when the ratio of B _s satisfies two or more.

Although the method for producing such aluminum hydroxide is not particularly limited, it is desirable that the concentration of Na contained in aluminum hydroxide is 0.1% by weight or less in terms of Na ₂ O and that it is desired as a filler. Gibbsite type aluminum hydroxide having an average primary particle diameter of twice or more the average secondary particle diameter can be obtained by pulverizing with a wet medium pulverizer. As the wet medium pulverizer to be used, for example, an attritor, a sand mill, a pearl mill, a Glen mill, an Apex mill and the like are used. If the average primary particle diameter of the aluminum hydroxide to be pulverized is not more than twice the average secondary particle diameter desired as a filler, it is difficult to satisfy the condition of 2 ≦ B _m / B _s , in which case heat resistance No improvement effect is seen.

Although the aluminum hydroxide for resin filling of the present invention is used for various purposes, it is preferable to appropriately select the particle size distribution of the particles to be used depending on the type of the resin to be charged. Thermosetting resins such as epoxy resins, phenol resins, urea resins, melamine resins, particle size distribution 4μ ≦ D ₅₀ ≦ 10μ D ₉₀ by sedimentation balance method when used as a filler such as silicon resin <D ₅₀ + 10 [mu] (Where D ₅₀ is the central particle size, and D ₉₀ is the particle size at which the weight accumulation from the fine particle portion becomes 90%) is recommended. In the case of the average secondary particle diameter in the above range, there is little problem in handleability due to an increase in viscosity when the resin and aluminum hydroxide are mixed, and in addition, the aluminum hydroxide precipitates in the resin before the resin cures, resulting in an uneven composite. The problem of generating is also reduced. Further, when the coarse particles are in the above range, the effect of improving heat resistance can be further seen, although the reason is not clear.

Such an aluminum hydroxide for filling a thermosetting resin can be obtained, for example, by grinding aluminum hydroxide having an average primary particle diameter of about 20 μ or more obtained by the Bayer method with a wet medium pulverizer. Grinding conditions include the type of crusher used, crushing capacity, type of crushing medium,
Since it is not unique depending on the amount of the medium, the shape of the medium, and the like, the conditions may be set in advance by a preliminary test. When the aluminum hydroxide after pulverization contains coarse particles in the above range or more, the coarse particles may be removed by sieving or the like before use.

When used as a filler such as a thermoplastic resin, for example, a polyolefin resin such as polyethylene or polypropylene, or a polystyrene resin, the particle size distribution by a sedimentation balance method is D ₅₀ ≦ 4 μ D ₉₀ <D ₅₀ +4 μ (wherein D ₅₀ is the median particle diameter, D ₉₀ is recommended to be in the range of illustrating the particle diameter at 90% by weight cumulative from fine portion). If the average secondary particle size is larger than the above range, the mechanical strength required for a molded article composed of the filling composition of the thermoplastic resin and aluminum hydroxide may decrease. Further, when the coarse particles are in the above range, the effect of improving heat resistance is further obtained.

The filling amount of the gibbsite type aluminum hydroxide of the present invention with respect to the resin is not unique depending on the use and is not particularly limited as long as it is within the range of the conventional aluminum hydroxide-filled resin composition. For example, in the case of an epoxy resin, 50 to 3
In the case of a thermoplastic resin, it may be used in the range of 20 to 200 parts by weight based on 100 parts by weight of the resin.

[0016]

The gibbsite-type aluminum hydroxide having the physical properties of the present invention described in detail above has succeeded in improving the heat resistance at a low cost without impairing the flame retardancy as compared with the conventional aluminum hydroxide. So, as a filler for thermosetting resin, for impregnating a flyback transformer of a television receiver, an insulating material for sealing electronic components, an electrical material such as a printed wiring board, or a wall covering material as a filler for a thermoplastic resin, It can be used for various purposes such as interior materials for automobiles, bathtubs, kitchen counters, building materials, etc., and its industrial value is extremely large.

[0017]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. In the examples, the powder physical properties of aluminum hydroxide (central particle diameter and cumulative 90% particle diameter and B _m / B
_s ), powder decomposition start temperature, resin composition obtained using aluminum hydroxide (resin filling particle size and solder heat resistance)
Were measured by the following methods.

(1) Median particle size (D ₅₀ ) and particle size of 90% cumulative (D ₉₀ ): Measured by using a sedimentation balance RS-1000 manufactured by Shimadzu Corporation.

(2) B _m / B _s (quantification of the degree of crystal disorder on the particle surface); B _s : each particle obtained from the spherical approximation BET of each particle size and the particle size distribution measured by a sedimentation balance method the specific surface area is calculated by integration by existing ratio B _m: N ₂ BET specific surface area B _s as measured by adsorption was calculated as specifically below. It reads the particle size distribution diagram as measured by sedimentation balance method to the computer, subdivided into minute interval 30 for the particle diameter, an average product of existence ratio spherical approximation BET diameter of each minute section, and the sum B _s did.

(3) Measurement of thermal decomposition initiation temperature; 7 mg of aluminum hydroxide was sealed in a 6 mm x 1.5 mm aluminum cell, and the temperature at which the endothermic reaction started when the temperature was raised at 10 ° C / min was measured. Starting temperature. Note that a differential scanning calorimeter DSC-40 manufactured by Shimadzu Corporation was used for the measurement.

(4) Resin filling viscosity: epoxy resin (Sumiepoxy ELA-128, manufactured by Sumitomo Chemical Co., Ltd.) 100
g and 100 g of aluminum hydroxide, and kneaded well until there are no aggregated particles of aluminum hydroxide.
c) and kept at 30 ± 0.1 ° C. for 1 hour.
o. The measurement was performed with the rotor No. 4 under the condition of 12 rpm.

(5) Heat resistance of solder (solder): JIS-C-
It was measured by a method according to 6481. Epoxy resin (Sumiepoxy ELA-128, manufactured by Sumitomo Chemical Co., Ltd.) 1
00g and 100g of aluminum hydroxide are mixed and kneaded well until there are no agglomerates of aluminum hydroxide, a hardener is added, and a glass casting frame (inner size: 150 × 150 ×
2 mm), cured at 170 ° C. for 2 hours, and taken out. Next, the cured product was cut into 25 × 25 × 2 mm squares, pretreated in a thermostat at 105 ± 2 ° C. for 75 minutes, floated in a solder bath adjusted to 300 ± 20 ° C., and taken out after a certain period of time. After cooling, cracks and the like on the resin surface were observed, and the longest time at which cracks and the like did not occur was taken as the solder heat resistance time.

Examples 1 and 2 The average primary particle diameter obtained by the Bayer method was 30 μm, the content N
a As ₂ O is 0.05% of coarse aluminum hydroxide pulverized raw material was pulverized under the following conditions using Apex Mill (grinding capacity 1 liter). Example 1 Grinding media: 2 mmφ zirconia balls 2.6 kg Mill rotation speed: 1980 rpm Slurry concentration: 550 g / liter Flow rate: 550 ml / min Example 2 Grinding media: 2 mmφ zirconia balls 2.6 kg Mill rotation speed: 1980 rpm Slurry concentration: 550 g / Liter flow rate: 400 ml / min After pulverization, solid-liquid separation, washing and drying were performed to obtain a high heat-resistant gibbsite-type aluminum hydroxide having powder properties as listed in Table 1. The thus obtained aluminum hydroxide was filled in an epoxy resin, and the resin filling properties were measured. Table 1 shows the results. The measuring method and the sample preparation method were performed according to the method described in the physical property measuring method.

Comparative Examples 1 to 3 Resin compositions were prepared in the same manner as in Examples 1 and 2, except that the following methods were used as aluminum hydroxide, and physical properties were measured. Table 1 shows the results. Comparative Example 1: The content of Na ₂ O obtained by the Bayer method was 0.1%.
5%, aluminum hydroxide having an average primary particle diameter of 20 μ was pulverized to 8 to 9 μ and then classified to remove a coarse component to obtain a sample. Comparative Example 2: Commercially available gibbsite-type aluminum hydroxide (trade name: H32ST, manufactured by Showa Denko KK) Comparative Example 3: Content of Na ₂ O obtained by the Bayer method was 0.0
4%, aluminum hydroxide having an average secondary particle diameter of 10 μ was weakly pulverized to 4 μ to obtain a sample.

[0025]

[Table 1]

Example 3 The thermal decomposition onset temperature of the aluminum hydroxide obtained by the pulverization of Examples 1, 2, and Comparative Examples 1 and 3 and the commercially available aluminum hydroxide of Comparative Example 2 were measured. As a result, the thermal decomposition onset temperature of aluminum hydroxide in Example 1 was 231 ° C., Example 2 was 236 ° C., Comparative Example 1 was 221 ° C.,
Comparative Example 2 was 222 ° C., and Comparative Example 3 was 224 ° C.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-52-80300 (JP, A) JP-A-62-246961 (JP, A) JP-A-2-199020 (JP, A) JP-A-6-1990 199519 (JP, A) JP 59-12605 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08

Claims (2)

(57) [Claims] 1. A (1) and the spherical approximation specific surface area B _s which is calculated based on the particle size distribution measured by sedimentation balance method, the ratio of the measured with N ₂ adsorption method BET specific surface area B _m is 2 ≦
A _{B m / B s, (2} ) containing Na concentration is not more than 0.1 wt% in terms of Na ₂ O, and (3) the particle size distribution by sedimentation balance method _{4μ ≦ D 50 ≦ 10μ D 90} <D Gibbsite-type hydroxide for filling with thermosetting resin, characterized in that it has a particle size of ₅₀ + 10 µ (wherein, D ₅₀ is a central particle diameter, and D ₉₀ is a particle diameter of 90% by weight accumulation from a fine particle portion). aluminum. Wherein (1) and the spherical approximation specific surface area B _s which is calculated based on the particle size distribution measured by sedimentation balance method, the ratio of the measured with N ₂ adsorption method BET specific surface area B _m is 2 ≦ B _m / B a _s, (2) containing Na concentration is not more than 0.1 wt% in terms of Na ₂ O, and (3) the particle size distribution by sedimentation balance method _{D 50 ≦ 4μ D 90 <D} 50 + 4μ ( wherein , D ₅₀ is the median particle diameter, D ₉₀ is a thermoplastic resin filling gibbsite type aluminum hydroxide, characterized in that a indicating the particle diameter at 90% in weight cumulative from fine portion).