JPS60172303A - Process for preventing caking of powder body obtained by crystallization - Google Patents

Abstract

PURPOSE:To obtain an effective process for preventing caking of powder body having tendency of forming cake obtd. by crystallization and to facilitate handling of the powder body in a process for obtg. powder body by crystallization by adding a specified polymer previously to a soln. contg. the powder body by dissolving. CONSTITUTION:In a process for obtg. powder body by crystallization, amorphous polymer of triethylenediamine existing in a soln. in the form of colloid and having low average mol.wt. selected from triethylenediamine polymers insoluble in water an org. solvent and having high heat resistance is added previously to the soln. contg. the powder body dissolved therein. The triethylenediamine polymer to be suitably used has <=3,000 average mol.wt., and suitable amt. thereof to be added is >=0.002pts.wt. per 100pts.wt. powder body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing caking of a powder that has caking properties among powders obtained by a crystallization operation.

Generally, powders have cohesive and adhesive properties, so they may solidify while being stored in a container such as a silo or drum. In particular, powders with strong hygroscopicity or powders with strong sublimation properties are easily solidified by a slight amount of moisture mixed in or by an increase in temperature. For this reason, powders with such caking properties require special care when handling, and if the powder solidifies, handling becomes extremely difficult. Measures to prevent caking include increasing the particle size of the powder itself, removing impurities in the powder, adding anti-caking agents to the powder, or storing the powder in a closed container. .

At present, this is done as appropriate by methods such as coating the powder surface with a suitable substance (microencapsulation).

However, powders of amines such as piperazine and triethylenediamine, powders of anthraquinone derivatives, and benzoic acid derivatives easily solidify with a slight temperature rise even when stored in a closed container.

These powders have strong sublimation properties and sublimate on the powder surface.

It is thought that during repeated coagulation, the contact area between powder particles increases, resulting in solidification. Addition of an anti-caking agent or microencapsulation are effective methods for preventing caking for all powders, including those with strong sublimation properties.

Conventional anti-caking agents used include silica powder and polyethylene glycol liquids, but additives ■↓
There was no effect unless the amount was increased to 0.002 to 1%. In addition, the microencapsulation method requires that after the powder is produced, it must undergo microencapsulation processes such as spray drying, vacuum evaporation, and interfacial polymerization, all of which require a large amount of equipment. However, the operation is complicated.

The present inventors have completed the present invention as a result of searching and researching a method for preventing caking that is easier to operate and more effective.

That is, the present invention provides a powder characterized in that, when obtaining a powder by a crystallization operation, a triethylenediamine polymer having an average molecular weight of Hs, ooo or less is added to a solution in which the powder is dissolved. The present invention provides a method for preventing caking.

The present invention will be explained in detail below.

In the present invention, the crystallization operation is performed by heating a solution in which the target powder is dissolved to evaporate the solvent, or by cooling a concentrated solution, or by performing evaporation and cooling at the same time. This is an operation to obtain powder, and there are no restrictions on the type of solvent or powder.

In the present invention, when obtaining a powder by the above-mentioned crystallization operation, water is used.

It is insoluble in organic solvents and has excellent heat resistance.It is amorphous and has a low average molecular weight, existing in colloidal form in solution. It is added to the solution in which it is being prepared.

The reason why caking is prevented in the present invention is considered to be as follows.

When a solution in which the powder is dissolved is heated and concentrated, the colloidal triethylenediamine polymer is uniformly dispersed in the solution. Next, when the concentrated solution is cooled to crystallize each other, the dispersed triethylenediamine polymer molecules serve as seed crystals, and crystals are generated and grown using these as nuclei. As the crystal grows, it incorporates triethylenediamine polymer molecules, and eventually the surface of the crystal is densely covered with triethylenediamine polymer molecules.
It is presumed that because sublimation and condensation on the crystal surface are significantly suppressed, an anti-caking effect can be obtained.

Triethylenediamine polymer can be produced from a low molecular weight with an average molecular weight of about 2,000 to a high molecular weight with an average molecular weight of about 30,000 by changing the polymerization conditions of the triethylenediamine monomer (polymerization temperature 9 polymerization catalyst). The triethylenediamine polymer used in the present invention has a wide variety of molecular weights.
The average molecular weight is 3.000 or less, preferably 2.500 or less. When the average molecular weight exceeds 3.000, the crystallinity of the triethylenediamine polymer molecules increases,
Triethylene diamine boron I is added to the solution in which the powder is dissolved.
Even if J or - is added, the dispersibility deteriorates. Then, when crystallizing the powder, it becomes impossible to uniformly contain the triethylenediamine polymer, making it impossible to obtain the anti-caking effect.

The amount added is 0,002 parts by weight per 100 parts by weight of powder.
There is no problem as long as it is more than 0.002 parts by weight, but 0.002 to 0.02 parts by weight is preferred from the viewpoint of economy and changes in the solidified layer. If the amount added is less than 0,002 parts by weight, it is difficult to suppress sublimation and coagulation on the crystal surface of the powder. This average molecule zs
To obtain a low molecular weight triethylenediamine polymer of less than .
It is preferable to carry out the polymerization at a temperature in the range of .degree. C. to 190.degree. C., but in order to obtain a low molecular weight triethylenediamine polymer on an industrial scale, a method using sulfuric acid as a catalyst is preferred.

The present invention has many superior features compared to conventional powder caking prevention methods, such as adding and mixing an anti-caking agent to powder that has caking properties, or microencapsulation methods. are doing.

For example, adding an anti-caking agent to a powder that has caking properties,
In the mixing method, after producing the powder, it is necessary to mix the powder and the anti-caking agent for a long time using a mixing device such as a pump blender-2 type mixer. In contrast, in the present invention, since the powder can be crystallized and at the same time can be subjected to caking prevention treatment, no mixing bags or rows are required. In addition, in the U method, silica powder or polyethylene glycol is usually used as an anti-caking agent, but the amount of these powders to be mixed is 0.02 parts by weight per 100 parts by weight of the powder. parts to i, o parts by weight, whereas
In this method, if the amount of triethylenediamine polymer mixed in the powder is at least 0.02 parts by weight per 100 parts by weight of the powder, an anti-caking effect can be obtained, and a very small amount is sufficient.

Adding an anti-caking agent may not affect the physical properties of the powder in some cases, but even if triethylenediamine polymer is contained in the powder, it will not have any effect on the physical properties of the powder. This is also a noteworthy point. Furthermore, in the present invention, when performing crystallization, particles of the powder to be crystallized are covered with triethylenediamine polymer, so it is considered that a type of microencapsulation is performed. Usual microencapsulation method (vacuum deposition method).

In the spray drying method, phase separation method, interfacial polymerization method, etc., once the powder is produced, equipment for making microcapsules, such as a vacuum evaporation device, a centrifuge, a drying machine, and a static tank, is used for polymerization. A reaction device is required, and interfacial polymerization requires polymerization to be carried out selectively only on the powder surface, so the polymerization conditions must be carefully controlled in a clean system free of impurities. In contrast, the present invention does not require any special equipment, and even if impurities are present in the system during crystallization, it is not affected at all, and process control is extremely simple. Furthermore, since there are no restrictions on the type of solvent or the type of powder, this is an innovative method for preventing caking that can be applied to all powders obtained by crystallization.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example-1 Triethylenediamine 3509' purified by sublimation in a flask with an internal volume of 6 + special grade methanol 100cc,
0.19 (0,0003 mol %) of 97% concentrated sulfuric acid was added and heated with a mantle heater, and the distilled methanol and a small amount of water were condensed and collected in a cooling tube. Liquid iII+i! When the temperature reached 174°C, the distillation valve was closed and the mixture was completely refluxed for 2 hours. Thereafter, the mixture is allowed to cool down to 60° C. or lower, and methanol is added to dissolve unreacted monomers. The resulting triethylenediamine polymer was allowed to precipitate, separated from the supernatant, washed six times with methanol, and dried under vacuum to obtain a triethylenediamine polymer with an average molecular weight of H2, soo (hereinafter referred to as TED+ket). Obtained 17Q.

Next, a methanol solution of piperazine having a composition of 40 parts by weight of piperazine and 60 parts by weight of methanol was put into a flask with an internal volume of 21, and the average molecular weight was 2.500.
of TEIIIA polymer was added. (00075 parts by weight per 100 parts by weight of piperazine) Heat with a mantle heater, stop heating when 300 cc of methanol has been distilled out, and immerse the flask in a water bath until the liquid temperature reaches 20°C. Cooling port closed. The crystallized piperazine was suction filtered through A30P paper, washed with a small amount of special grade methanol, and then vacuum dried to obtain piperazine 83.

Take a portion of the piperazine thus obtained and -side 5an.

It was packed in a box with a height of 2 cnr, a plastic plate of 5 II on each side was placed, a weight of 3009 was placed on top of it, and the product was stored in a desiccator. The pressure applied to piperazine is 12
g/cnr, and this value corresponds to the pressure applied at the center of the drum when piperazine is packed into a 25 to 9 fiber drum.

After storing it in a desiccator for one month, remove the weight and box, put the plastic plate down, and measure it with a bookstore type hardness tester.
Pressure was applied to the center of the piperazine mass and the pressure was read when the piperazine mass was crushed.

The crushing pressure was 0.0'5 kg/crfl, and no caking occurred. The value thus measured was defined as the degree of caking, and the caking tendency of the powder was quantitatively evaluated. In the following Examples and Comparative Examples, the degree of consolidation was measured in the same manner.

For comparison, exactly the same operation was performed except that no TKDA polymer was added. The solidified dust of piperazine obtained was 5
．． It was 8 kg/cr/l and solidified to the inside.

Example 2 In Example 1, TEDA polymers with various average molecular weights obtained by variously changing the operating conditions were added in the same manner as in Example-1, and the relationship between the average molecular weight of the TEDA polymer and solidified dust was investigated. Ta. The results are shown in FIG. As is clear from FIG. 1, the average molecular weight of the TEDA polymer is s,
When the temperature exceeds o o o, the consolidated dust rapidly increases in size. On the contrary, it can be seen that when the average molecular weight becomes 5.000 or less, the amount of solidified dust approaches almost zero.

Example 6 1.000 liters of an ammonium chloride aqueous solution having a composition of 65 parts by weight of ammonium chloride and 65 parts by weight of water was prepared to an internal volume of 2 I!
T of the average molecule 1j12.700 obtained by changing the operating conditions in Example 1.
EDA polymer 0029 was added. (6 parts by weight of a, oo for 100 parts by weight of ammonium chloride) Heat with a mantle heater, stop heating when 300 cc of water has been distilled out, and immerse the flask in a water bath until the liquid temperature reaches 2.
It was cooled to 0°C. The crystallized ammonium chloride crystals were suction filtered using 7'scP paper, washed with a small amount of pure water, and then vacuum dried to obtain 98 ammonium chloride crystals. As a result of measuring the amount of solidified dust of the ammonium chloride crystals thus obtained, it was found to be 0.05 kg/ctft, indicating that there was no solidification at all. For comparison, the solidified dust of crystals obtained by performing exactly the same operation except that no TEDA polymer was added was measured, and it was found to be solidified at 2.3 kg lcr&.

Example 4 A methanol solution of triethylenediamine monomer having a composition of 40 mm and 60 parts by weight of methanol was placed in a flask with an internal volume of 21 mm, and T with an average molecular weight of 2,500 obtained in Example 1 was put into a flask with an internal volume of 21.
EDA polymer 0049 (001 parts by weight per 100 parts by weight of triethylenediamine monomer) was added. Heat methanol to 350 c using a mantle heater.
c After distillation, heating was stopped, the flask was immersed in a water bath, and cooled to the liquid temperature of 20°C. The crystallized triethylenediamine monomer was converted into A5 (! Ff
[After suction filtration and washing with a small amount of special grade methanol, vacuum drying yields triethylenediamine monomer 113.
! I got 17. The solidified dust of the triethylenediamine monomer thus obtained was 0.03 kg/cr/I and was not solidified at all.

Example-5 Consolidated dust and TKDA were obtained by performing the same operation as in Example-4 by varying the amount of TEDA polymer added.
The relationship between polymer-added nails is shown in Figure 2. As is clear from FIG. 2, when the amount of TEDA polymer added to 100 parts by weight of triethylenediamine monomer becomes less than 0002 parts by weight, the consolidated dust begins to grow and becomes 0001 parts by weight.
When the amount is less than parts by weight, the size of the solidified dust increases rapidly. On the other hand, when the amount added increases, it can be seen that there is almost no difference in the amount of solidified dust even if the amount increases by 0.02 parts by weight or more.

Example-6 An aqueous ammonium sulfate solution (1.0009 g) consisting of 40 parts by weight of ammonium sulfate and 60 parts by weight of water was put into a flask having an internal volume of 21, and the average molecule obtained in Example 1 was [2,50 parts by weight].
0 TEDA polymer 0029 (ammonium sulfate 10
0005 parts by weight relative to 0 parts by weight) was added and heated with a mantle heater.

When 400 cc of water was distilled off, heating was stopped and the same operation as in Example 6 was carried out to obtain 241 ammonium sulfate.
I got a 9. The solidified ammonium sulfate dust thus obtained was 0.1 kg/cnl and was not solidified at all. On the other hand, when the TEDA polymer was not added, the solidified dust was solidified to the inside at 4.1 kg/crd.

Example-7 An aqueous solution of IJium chloride, consisting of 28 parts by weight of IJium chloride and 72 parts by weight of water, 1.500 parts by weight! ;l,
The TEDA polymer 0059 (with an average molecular weight of 12.500 obtained in Example 1) was placed in a flask with an internal volume of 21 mm.
0.012 parts by weight per 100 parts by weight of sodium chloride) was added and heated with a mantle heater.

Sodium chloride was crystallized while water was evaporated, and when 50 Occ of water was finally distilled off, the crystallization operation was stopped and 136 g of sodium chloride was obtained.

The degree of solidification of the sodium chloride thus obtained is 0.11.
(9/CH7 was not solidified at all. On the other hand,
When the TEDA polymer was not added, the degree of consolidation of thorium chloride was 2.8 kg/Cnl.

Example 8 20 parts by weight of sodium chloride, 70 parts by weight of water, and 10 parts by weight of alkyl pyrazines and polyethylene amines as impurities. 0.0431;
1 (0,012 parts by weight per 100 parts by weight of sodium chloride) was added and heated with a mantle heater. 600 yen of water
9 was distilled off, the heating was stopped, and the rest of the procedure was carried out in the same manner as in Example 7 to obtain 107 g of sodium chloride. The degree of consolidation of the IJium chloride obtained in this way is 0.1 k
g 1crd and was not solidified at all. On the other hand,
If TEDA polymer was not added, the degree of consolidation was 2.
．． It was solidified at 7 kg/cr/l.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the average molecular weight of a TEDA polymer and the degree of consolidation. FIG. 2 is a diagram showing the relationship between the amount of TED'A polymer added and the degree of consolidation. Patent applicant Toyo Soda Kogyo Co., Ltd. Figure 7 10.000 20.000 T E D A Hori v - (7) sl<uniform molecular weight -,
i, i 21st

Claims (1)

[Claims] 1. When obtaining powder by crystallization operation, the average molecular weight is 3.0
The anti-caking power of powder is characterized by adding a triethylenediamine polymer having a particle size of 0.00 or less to a solution in which the powder is dissolved.