JPS58217423A - Finely powdered silicic acid hydrate - Google Patents

Abstract

PURPOSE:To obtain a superior carrier for agricultural chemicals by providing high oil absorbing power and relatively low bulkiness to finely powdered silicic acid hydrate. CONSTITUTION:This finely powdered silicic acid hydrate absorbs >=0.4ml/ml linseed oil (value a) when a kneading method using a machine is applied under the provisions of JIS K5101, it absorbs >=0.6ml/ml linseed oil (value b) when the Gardner-coleman method is applied, and the ratio of b/a is <=1.5. The powder volume of the silicic acid hydrate obtd. from the apparent specific gravity under the provisions of JIS K6220 is 5-5.8ml/g. The silicic acid hydrate is manufactured by a known wet process by which silicate is decomposed with acid in the presence of water while suitably regulating the concns. of both the solns., the acid adding speed, the temp., etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved fine powder hydrated silicic acid which has a low particle size and has as low a powder cavity as possible.

As is well known, the oil absorption capacity of a powder is the amount by which a specific oil (usually linseed oil) fills the voids in the powder per unit weight.

Furthermore, it is the volume of oil that covers the surface of the powder particles, and is a convenient characteristic (physical property) for estimating the structural properties of the powder particles. Therefore, the smaller the powder particles are, the more uneven the particle surface is, and the more voids are formed between aggregated secondary and tertiary particles, the greater the amount of oil absorbed.

On the other hand, it is unavoidable that the height of the powder increases.

Micropowdered hydrated silicic acid (usually referred to as silica), which has a developed structure, is used as a filler for rubber reinforcement, as a carrier for agricultural chemicals, and for other purposes such as absorbing liquid and pulverizing feed, surfactants, etc. Although they are frequently used, powders with high cavities significantly reduce the efficiency of handling them in various ways.

Particularly when used as a pesticide carrier, it cannot be overlooked that the hydrated silicic acid particles are mixed with the hydrated silicic acid powder and adsorbed with the hydrated silicic acid particles through crushing, mixing and/or kneading. The agglomerated structure of the product is destroyed, and even if it is initially highly oil-absorbing, its oil-absorbing property decreases as it undergoes various formulation operations. Although the currently commercially available fine powdered hydrated silicic acid has high oil absorption as a product, when it is actually used for each purpose, the aforementioned low oil absorption occurs, resulting in various practical problems (e.g. (e.g. oozing of pesticide ingredients) has been pointed out.

Therefore, the present invention was proposed with the intention of improving the basic physical properties of finely powdered hydrated silicic acid.

That is, an object of the present invention is to provide a highly oil-absorbing finely powdered hydrated silicic acid. Another object of the present invention is to produce finely powdered water in which the agglomerated structure of each particle is strong, and the agglomeration is difficult to break even when subjected to stirring, kneading, etc., and the high oil absorption performance can be maintained as it is. Our objective is to provide Japanese silicic acid.

Furthermore, another object of the present invention is to provide a highly oil-absorbing product.

Its purpose is to provide finely divided hydrated silicic acid with relatively low ivy.

For measuring the oil absorption of powders such as finely divided hydrated silicic acid, we use the "spatula kneading method" specified in JIS K310/, and another method, for example, the Abtsu method specified in JIS K Otsu 22/. There is a mechanical method using a butometer, and both of these methods are commonly used as the "kneading method."

By the way, when measuring the oil absorption of hydrated silicic acid using this kneading method, as mentioned above, a certain degree of structural destruction due to kneading etc. is unavoidable, so in order to obtain fair measured values, the measurement conditions, that is, kneading etc. It is important to keep the combined pressure, kneading time, kneading and stirring speed, and amount of sample to be measured constant, but with the above-mentioned spatula kneading method, it is extremely difficult to actually make measurements while keeping these conditions constant. However, the situation is such that there is no equivalent official regulation except for very basic conditions. Furthermore, even in the case of the 9-mechanical method, there are problems such as the amount of sample cannot be kept constant depending on the buds of the sample.

Against this background, the present inventors investigated various measurement conditions using the above-mentioned mixing method in order to obtain more accurate and objectively reliable oil absorption values, and first, the Ishikawa method +/ Use θ/1 lightning crusher.

Spring pressure 23! In order to eliminate the error factor during measurement, the sample amount is 2f and the kneading time is fixed at 9 minutes under the condition where the pestle of +39 is rotating and kneading in the mortar at lt times/min. I tried. The measurement method described above significantly improves measurement accuracy including reproducibility compared to the above-mentioned spatula kneading method.

However, since such a method is a type of kneading method, some degree of destruction of the particle structure during measurement cannot be avoided. Therefore, in order to know the oil absorption amount before the agglomerated structure of hydrated silicic acid is destroyed, it is necessary to perform measurements without mixing as much as possible, that is, under conditions where the sample is subjected to as little shearing and pressure as possible. By comparing the oil absorption value in this case with the value measured by the kneading method described above, it becomes possible for the first time to estimate the strength of the agglomerated structure of the hydrated silicic acid.

The Gardner-Koleman method (G,
arrlner-Coleman Method,
(hereinafter referred to as GC method) is suitable. The present inventors published the "Pigment Handbook" (edited by Japan Pigment Technology Association) in 1939 (Showa 3).

When measuring the kneading method oil absorption amount, the GC method was also used and the measured values of both methods were compared. Naturally, due to differences in measurement conditions, the GCC method oil amount and the kneading method oil absorption amount do not match.

The smaller the difference, that is, the smaller the value of oil absorption by GC method vs. oil absorption by kneading method, the smaller the destruction of the particle structure due to mixing, crushing, kneading, etc., and the stronger the agglomerated structure of the particles. It is something.

In addition, it is generally known that highly oil-absorbing hydrated silicic acid is highly oil-absorbing, but in order to compare the relationship between this oil-absorbing property and ivy, the unit of oil absorption is linseed oil per powder volume. It is preferable to express it in terms of adsorption amount.

In addition, the powder volume of hydrated silicic acid is all JIS K Otsu 2.
It can be expressed as the reciprocal of the apparent specific gravity defined in 20.

Next, we selected three typical types of finely powdered hydrated silicic acid that are currently commercially available as agricultural chemical carriers using this method.
The oil absorption and powder volume were measured and the results shown in the table below were obtained.

Table 1 Tarishi.

Commercial product A is TOKUSHIEL P manufactured by Tokuyama Soda Co., Ltd. Commercial product B is 9 Nippusi JLNST manufactured by Nippon Silica Co., Ltd. Commercial product C
is Carplex≠lθ manufactured by Shionogi & Co., Ltd.

From the above results, for hydrated silicic acid to be excellent in both workability and quality, it is necessary to have a powder volume (bulk) of less than vrl/I and a kneading method oil absorption per volume of 01 A2 ml/me or more. Furthermore, it is said that the oil absorption amount obtained by the GC method is approximately SO higher than that obtained by the ordinary kneading method (Pigment Handbook, p. This is clear from the fact that the values of GC method oil absorption vs. kneading method oil absorption (b/a) are both over 7.50.

Each of these known products has practical problems. Setting this value to /, 30 or less means that the structural destruction of hydrated silicic acid due to kneading etc. is reduced, and it can be used as a conventionally known commercially available carrier when mixed with, for example, agricultural chemical ingredients under harsh conditions. It will be more convenient than goods. Ta\
However, if we limit ourselves to the fact that the amount of oil absorbed per unit volume is large, in the case of extremely low electric current, even if the oil absorption is poor, the amount of oil absorbed per unit volume may not be so small.

Therefore, it is important that the powder actually has a volume within a certain range, and that each oil absorption amount by the G-glue and kneading methods is high within this volume range.

The present invention was developed based on the above idea.

In other words, the gist of the present invention is that the amount of oil absorbed by linseed oil is J
011θynVtnt or more (K value) in the case of kneading method using a crusher based on ISK310/regulations.

In the case of the GC method, the b value is 060πl/ni or more, and the b/a value is /! It consists of fine powdered hydrated silicic acid with θ or less. Furthermore, the fine powder hydrated silicic acid of the present invention is characterized in that the powder volume determined from the apparent specific gravity according to JIS K2nθ is 0 to 1 ftnt/I. As mentioned above, the fine powder hydrated silicic acid according to the present invention has an oil absorption amount by linseed oil based on JIS K3; 10/regulation.
0110 ml/n1 in case of kneading method using a crusher
As mentioned above, in the case of the GC method, it is necessary that it is 0 Oml/m1 or more. By the kneading method using a crusher based on this JIS K3101 regulation; if the amount of linseed oil slick oil is less than θ'l Ome / m1, and if the amount of linseed oil slick oil determined by the GC method is less than 0 θttti / m1 However, depending on the type of pesticide active ingredient, it is not possible to adsorb a sufficient amount of it, making it difficult to use it as a pesticide carrier. Furthermore, the powdery hydrated silicic acid characteristic of the present invention has a ratio of the oil absorption amount by the GC method to the oil absorption amount by the kneading method.
It is an essential requirement that this value be 50 or less, but this value is /,! ;If it exceeds 0, it will lead to a significant decrease in oil absorption under harsh conditions.
Alternatively, this is not preferable since it may cause problems such as a decrease in powder fluidity.

In addition, the fine powder hydrated silicic acid of the present invention is thus highly oil-absorbing, and at the same time has a BET surface area of 100 m''/
The above is better<ha/ 30 m'/ or more I
It has a high value of Q, and can be used not only as a pesticide carrier, but also as a chemical carrier.
It can be expected to be used in a wide range of applications, including adsorbents, catalyst carriers, rubber reinforcing agents, and fillers for paints.

The improved fine powder hydrated silicic acid of the present invention does not require any sophisticated manufacturing method, but can be manufactured using a known wet manufacturing method in which a silicate (e.g., sodium silicate) is decomposed with an acid in the presence of water. Although it is manufactured.

In particular, in this case, hydrated silicic acid of the desired quality can be obtained by appropriately adjusting and combining the concentrations of both liquids, acid addition rate, temperature, etc.

Hereinafter, the features of the present invention will be described in more detail with reference to Examples.

[Manufacture of hydrated silicic acid] Example 1 Commercially available sodium silicate (SiO, 2/Na
Add solution 311, which is obtained by diluting r O ratio 32) with water to give a SiO2 concentration of 7 to 1/71, and while stirring, maintain the temperature at SoC, H, So, concentration! Add θg/II of sulfuric acid/l-1ml in 4 minutes. Immediately thereafter, 1 ml of sulfuric acid of the same concentration/7'' was poured over 3 g/min.

At this time, the liquid temperature is raised to 9A°C at a rate of f'c1 minute, and thereafter maintained at 9j to 97°C. After addition of sulfuric acid, the mixture was aged for 5 minutes at a temperature of about 500 ml, and then the pH was adjusted to 500 ml while cooling.

Slurry as usual? After filtering and washing with water, solid content concentration/
A suspension of 0.00 fl/l was prepared, the pH was readjusted to 0.00 fl/l, and the suspension was filtered, washed with water, dried and pulverized to obtain a fine powder of hydrated silicic acid 3jθg having the following physical properties.

(1) Oil absorption (a) Kneading method 01A II ml/ml (
1)) G C method θotjda l/m1(C)
1) /a/', guar g (2) Powder volume -yot9πl/g (3) BET surface area 225 m'/g Example U Same stirring tank as used in Example 1, sodium silicate solution and sulfuric acid 31jπt of sulfuric acid was added over 6θ minutes while stirring and keeping the temperature at 5°C. Thereafter, the temperature of the reaction system was raised to 93°C, and aged at this temperature for 6θ minutes.Then, the pH of the contents was adjusted to 4, and the same treatment as in Example 1 was carried out as follows. Obtain microcormorant-like hydrated silicic acid with unique physical properties.

(1) Oil absorption (a) Kneading method θgψ41 (1+) GC method Otsu3πl/m1 ((d)
b/a /, gu32 (2) Powder volume Yoda l/g (3) BET surface area 277 m'
/9 [Experiment using agricultural chemical carrier] Example 3 Production according to Example 1 and oil absorption amount (a) by kneading method
) is Og Otsu π//lrl, GC method) is θ Otsu 4' m//ml + the above +3/a is Z3 Otsu,
The powder volume is 5:3θml'! Regarding the fine powder hydrated silicic acid according to the present invention whose + and BET surface areas are 253 m and 2Ag, and the three commercially available hydrated silicic acids,
Each of these hydrated silicic acids lθ0g town 1. Dibutyl phthalate (hereinafter referred to as DBP) was added at 0πl and 1gθml using a twin-shaft table kneader (Model DNV-/manufactured by Irie Shokai).
is added at a rate of 10πt/min. Next, this material is pulverized and mixed using an atomizer (Model FA-3W-/manufactured by Fudo Sangyo). The thus obtained DBP mixed powder was hardened and its apparent specific gravity, loosened apparent specific gravity, and angle of repose were measured using a PT-D type powder tester manufactured by Koiyo Iron Works. The results are in Table 2.
As shown in Table 3.

(Left below) As shown in the table above, the hydrated silicic acid of the present invention is lower in bulk than commercially available products, with less change in volume, both without and after addition of DBP, and because of its low compressibility, it has good fluidity and handling. It turns out that it is advantageous.

Additionally, DBP/ff for 0 g of hydrated silicic acid lθ
Especially when a large amount of DBP is added, as in the case where Oml is added 5, the oil absorption capacity of hydrated silicic acid decreases due to crushing and mixing, and the bulk rapidly decreases due to DBP oozing out, and at the same time, the degree of compaction increases. However, the product of the present invention exhibits less electrical charge and decrease in fluidity than other commercially available products, and can sufficiently withstand high-concentration kneading with agricultural chemical ingredients. It is shown that.

Examples Three representative pesticide active ingredients for each of the hydrated silicic acids used in Example 3: Sumithion (registered trademark of Sumitomo Chemical Co., Ltd.) and Diazinon (registered trademark of Ciba Geigy)
and Kitazine (registered trademark of Kumiai Chemical Industry Co., Ltd.), the oil absorption was measured by the kneading method and the GC method according to the method described above.

The results are shown in the table below.

(The following is a blank space) As in the case of Example 3, this result also shows that the hydrated silicic acid of the present invention has a large oil absorption amount per volume.

Furthermore, it can be seen that the decrease in oil absorption capacity due to kneading etc. is clearly smaller than that of other commercially available products.

Claims (2)

[Claims] (1) ``The oil absorption amount by linseed oil is JIS K310/
0110 in case of kneading method using a crusher based on regulations
A fine powdered hydrated silicic acid characterized by having a value of πξ1 or more (a value), a value of not less than 0 (b value) in the case of the Gardner-Koleman method, and a bZa value of /jO or less. (2) The fine powder hydrated silicic acid according to claim (1), wherein the powder volume determined from the apparent specific gravity according to JIS K Otsu 22θ is θ˜51r″′17.