JP2887679B2 - Method for producing condensed ammonium phosphate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a condensed ammonium phosphate. More specifically, the present invention relates to a condensed ammonium phosphate which is condensed in a short time while preventing temperature unevenness during heating and does not impair the whiteness and PH of the product.

(Prior art) Phosphoric acid-containing material and ammonia-condensing agent
When producing condensed ammonium phosphate, it is essential to provide thermal energy. Heretofore, known methods of applying this heat energy include: A. A method of heating in a liquid heat medium (for example, Japanese Patent Publication No. 47-38).
319) B. Heat transfer from a heating pot, a heating furnace, a heating vessel, etc. (for example, JP-B-49-30356, JP-B-52-4280, JP-B-53-15478). Is also an external heating method using a heat medium.

(Problems to be Solved by the Invention) When a mixture of a phosphoric acid-containing substance and an ammoniated condensate is heated, soft melting starts from a material temperature of around 110 ° C and 140 ° C.
The viscosity gradually increases at ~ 160 ° C with vigorous foaming, and the whole solidifies through a paste. At this time, in the known external heating method, a. Foreign matter such as metal powder is mixed by physical and mechanical polishing.

b. It takes 2 to 3 hours to complete the reaction, and it cannot be processed efficiently.

c. The viscous and solidified substances adhere to the stirring blades and vessel walls, causing temperature unevenness especially where they contact the heat transfer surface and where they do not.

d. This long time is required, and as a result of the temperature unevenness, the whiteness of the product is deteriorated. In particular, there is a problem in using it as a paint flame retardant.

In addition, since there is a portion that is exposed to high temperatures for a long time, ammonia is desorbed to lower the product PH. In particular, when used as a flame retardant for papermaking, burning of papermaking is a problem.

The present invention seeks to provide a manufacturing method that solves these problems.

(Means for Solving the Problems) In order to achieve the above object, the inventor examined physical, chemical, and electrical characteristics of each raw material.

The present invention relates to a method for producing a condensed ammonium phosphate, which comprises subjecting a mixture comprising a phosphoric acid-containing substance and an ammoniating-condensing agent to heat condensation by heating with high frequency to produce a condensed ammonium phosphate.

The phosphoric acid-containing substance of the present invention includes ammonium hydrogen phosphate, ammonium dihydrogen phosphate, phosphorus pentoxide, condensed phosphoric acid, condensed ammonium phosphate, urea phosphate and the like.

The ammonification-condensing agent of the present invention is, for example, ammonium urea carbamate. Of these, urea is preferred.

The mixture of the phosphate-containing and the ammonification-condensing agent is:
The molar ratio, 1 to 2 of the ammonia-condensing agent per phosphoric acid-containing substance is preferred. If it is less than 1, the reaction requires a long time, and the solidified product is easily fused to the container.
If it exceeds 2, the concentration of phosphoric acid decreases. When the mixture is impregnated with water, the treatment capacity is improved, and the water content is preferably 0.1 to 1 part by weight of water per 100 parts by weight of the mixed raw material. This is because high frequency waves are intensively absorbed by water and are heated to promote the thermal condensation reaction of the main reaction. If the amount of water is excessive, energy is lost due to evaporation of the water, and if the amount is more than 5%, the efficiency is poor.

The condensed ammonium phosphate obtained by the production method of the present invention can be exemplified by the general formula (NH ₄ ) _{n + 2 Pn} O _{3n + 1} n> 20.

In the high-frequency heating method of the present invention, a mixture of a phosphoric acid-containing substance and an ammoniated monocondensing agent is placed between electrodes,
A strong high-frequency voltage is applied to this, and the internal heat generated by the dielectric loss of the mixture is used as a heating source. The frequency may be any frequency used for industrial heating sources, and among them, internationally assigned frequencies of 915 MHz and 2450 MHz are preferable. Oscillation output is 0.
5 to 6.0 kW can be produced economically. The high-frequency irradiation time may be selected according to the output of the oscillator and the amount of processing to be solidified, and may be about 30 minutes with an oscillator output of 6 KW and a phosphoric acid content of 1 kg.

(Effect of the Invention) Since the manufacturing method of the present invention is internal heating by high frequency,
Uniform heating is possible, and it can be produced without stirring during heating.

Since the production method of the present invention can be produced without stirring, foreign matter such as metal powder or the like due to a processed product or mechanical polishing can be prevented from being mixed.

Since the manufacturing method of the present invention is internal heating by high frequency,
Since uniform heating can be efficiently performed, the reaction is completed in a short time.

Since the manufacturing method of the present invention is uniform internal heating by high frequency, there is no temperature unevenness in the product.

Since the manufacturing method of the present invention is internal heating by high frequency,
Since there is no temperature unevenness in a short time, the whiteness of the product is not deteriorated.

Since the production method of the present invention is a short-time heating with uniform internal heating by high frequency, ammonia is less desorbed and the product PH is close to neutral. Therefore, the reaction vessel and the like are not corroded and impurities such as iron are not mixed.

In the production method of the present invention, since the temperature of the reaction product drops after the reaction is completed, the dissociation of the ammonia group does not occur, and therefore, it is not necessary to intentionally use an ammonia atmosphere.

As described above, the production method of the present invention eliminates the steps of stirring and injecting ammonia gas, and can be produced efficiently in a short time.The condensed ammonium phosphate of the present invention has good whiteness, PH is almost neutral, and papermaking is performed. It can be suitably used as a flame retardant for paints, paints and resins.

(Example) The unit and the evaluation method are as follows.

Oscillator output is TMB-5100 type manufactured by Toshiba Corporation, output 3kW,
The one with a frequency of 2450 Hz was used.

The power consumption is KW including the time required for 1 kg of NH ₄ H ₂ PO ₄
h was determined.

10% slurry PH 10 g of the obtained condensed ammonium phosphate powder was suspended in 90 g of pure water, and the suspension was stirred at room temperature for 60 minutes. Next, the suspension was centrifuged to settle the powder, a part of the supernatant was taken out, and the pH at this time was determined.

Elution rate% A part of the supernatant was taken out, precisely weighed, dried, and the elution amount was measured from the weight of the precipitate.

Whiteness T% The reflectance was determined using a photoelectric whiteness meter manufactured by Kett, with the reflectance of standard MgO being 85 with 400 mμ light.

 Iron (ppm) Determined by atomic absorption method.

 Peelability from container Judged visually.

Example 1 A mixture of 1000 g of ammonium dihydrogen phosphate and 680 g of urea was spread on a 500 mmφ Teflon flat plate to a thickness of 20 to 30 mm,
Irradiated with high frequency of output 3kW frequency 2450Hz. The temperature of the mixture measured by a fiber-type radiation thermometer became soft melting and foaming from around 120 ° C., and became 250 ° C. in 40 minutes after passing through a paste, and the whole was solidified as a porous foamed pair. Even after irradiation, the temperature of the reaction product subsequently dropped. The foam was easy to peel off without fusing to the container. This foam was ground to 100 mesh. This whiteness is 98
And pure white. Condensation degree by end group titration method is 12.
0, Iron as impurity is 10ppm, 10% slurry PH is 6.2
Met. These are shown in Table 1.

Reference Example 1 The physical properties of a mixture of 1000 gr of ammonium dihydrogen phosphate and 680 gr of urea before high-frequency irradiation were measured.

Comparative Example 1 1000 g of ammonium dihydrogen phosphate and 680 g of urea were added to a kneader indicated with a rotary kneading blade and a heating jacket.
And the mixture was heated. 120 minutes after 60 minutes
And softening began, and the viscosity increased with vigorous foaming at 150 to 160 ° C for up to 120 minutes, and completely solidified at 170 ° C after 180 minutes through the paste. The device continued to violently vibrate, and eventually failed to withstand heavy loads and stopped naturally. The product solidified and attached by a jig equipped with a cutting blade was artificially unraveled and taken out. At that time, the blades and the vessel wall adhered stubbornly, especially on the vessel wall contact surface, where the product was exposed to high temperature and ammonia groups were dissociated, and partly became polyphosphoric acid and the vessel wall corroded. Was. The reaction product was pulverized through 100 mesh, and the quality was evaluated according to Example 1. These are shown in Table 1.

Comparative Example 2 Comparative Example 1 was followed except that heating was performed while injecting ammonia gas continuously at 2 L / min.

Comparative Example 3 Sumitomo Chemical Sumisafe P was obtained as a commercial product and evaluated according to Example 1.

Examples 2 to 6 0.1 to 10 parts by weight of water shown in Table 2 was added to 1000 gr of ammonium dihydrogen phosphate and 680 gr of urea, and the mixture was spread on a Teflon flat plate. Irradiated until solidified. The obtained condensed ammonium phosphate was precisely weighed. Further, this condensed ammonium phosphate was pulverized with a pestle, and the condensed ammonium phosphate was produced according to Example 1 and evaluated as shown in Table 2.

Impregnation with an appropriate amount of water shortens the required time and improves the processing capacity, and the water content is preferably 0.1 to 1.0 part by weight. If the water content is excessive, energy is deprived by evaporation of the water content, and power consumption increases by 5% or more.

The reaction product was obtained as a hollow foam, which was easily peeled from the container and easily pulverized, without impairing the color (whiteness).

Examples 7 to 8 Microwave irradiation was performed in the same manner as in Example 1 except that the molar ratio of ammonium dihydrogen phosphate and urea was changed to various ratios indicated. Table 3 shows the irradiation results. The releasability from the container and the hue (whiteness) were the same as in Example 1 and were good.

Claims (3)

(57) [Claims] (1) A method for producing a condensed ammonium phosphate, which comprises heating and condensing a mixture comprising a phosphoric acid-containing substance and an ammonia-condensing agent by heating at a high frequency to produce a condensed ammonium phosphate. 2. The process for producing a condensed ammonium phosphate according to claim 1, wherein water is added in an amount of 0.1 to 1 part by weight based on 100 parts by weight of a mixture comprising the phosphoric acid-containing substance and the ammonia-condensing agent. 3. The process for producing condensed ammonium phosphate according to claim 2, wherein the phosphoric acid-containing substance is ammonium dihydrogen phosphate and the ammoniating-condensing agent is urea.