JPS59101454A - Process for cooling and crystallization of molten guanidine sulfamate - Google Patents

Abstract

PURPOSE:To carry out the crystallization of the titled compound in a short time, by reacting dicyandiamide with ammonium sulfamate under molten condition, casting the molten liquid in a thin film, generating seed crystals at the surface of the cast film before solidification, and continuing the cooling of the molten liquid. CONSTITUTION:Dicyandiamide is made to react with ammonium sulfamate or with sulfamic acid and ammonia under molten condition, and the obtained molten reaction product is cast on a rotary belt in the form of a thin film at 135-145 deg.C. Prior to the solidification of the molten liquid, seed crystals are generated at the surface of the liquid by cooling the surface with air stream blasted from the air nozzle 3 and applying vibration force to the liquid. Successively, the thermal medium of 10-55 deg.C is sprayed through the water-spraying nozzle 4 to the reverse face of the belt to cool and crystallize the objective compound. The presence of the seed crystals prevents the supercooling of the molten liquid, proceeds the crystallization smoothly in a short time, and prevents the fluctuation of the time necessary to start or finish the crystallization caused by the supercooling phenomenon.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cooling and crystallizing a guanidine sulfamate melt. More specifically, the present invention relates to a cooling crystallization method in which the melt is cast in a thin layer, seed crystals are present on the surface of the cast material before assimilation, and the material is subsequently cooled.

The most common method for cooling and crystallizing a guanidine sulfamate melt is to pour the melt into a tray with a depth of about 5 CIJI to a thickness of about 2 to 41 mm, and then cool it by standing or cooling it from the outer wall. This is a method of solidifying it. However, all of these cooling methods require a long time, several hours or more, to complete cooling, and are not industrially practical. Further, the thickness of the melt layer in the tray is set to 0.5, for example.
If it is made thinner and easier to cool, such as in the case of 10 to 10, the molten liquid may be supercooled and the time required for solidification and crystallization may vary widely, and such a method is also not industrial.

In order to solve the above problems, Special Public Interest Publication No. 57-85869
In the invention of No. 1, the crystallization time is shortened by casting the melt into a thin layer and cooling in two stages: slow cooling and normal cooling. However, in this method, the range of slow cooling conditions (note: the temperature of the solidified material) in the stage before the two-stage cooling is wide;
It becomes necessary to adjust the slow cooling conditions depending on the properties of the melt,
If the adjustment is not appropriate, there is a problem that good crystals cannot be obtained.

Therefore, the present inventors conducted intensive research on the crystallization method, which does not have the drawbacks of the above-mentioned known techniques. As a result, it was possible to consider that the reason why it is difficult to adjust the slow cooling conditions using the known method is as follows.

In other words, attached Figure 1 is a temperature one-hour curve related to the cooling solidification of molten materials in general, but when a high-temperature molten material is cooled, it solidifies even after the melting point (freezing point) A of the molten material. (crystallization) does not start and is supercooled to a lower point B. When crystallization begins, the temperature of the melt increases, returns to the melting point C, and is maintained at the same temperature at the end point D1 of crystallization. Then, with the completion of crystallization, the temperature of the solidified product begins to decrease and, depending on the degree of cooling, decreases to the 9E point.

The degree of supercooling can vary widely depending not only on the slow cooling conditions of the melt, but also on the production conditions of the melt in the present invention, that is, the reaction conditions of dicyandiamide and ammonium sulfamate (or sulfamic acid and ammonia). .

Therefore, in order to prevent such fluctuations in the time required from the start of crystallization to the end of crystallization due to the passage of the supercooling period, it is sufficient to prevent the melt from entering the supercooling stage at all. Based on this consideration, extensive research has revealed that by adding seed crystals to the melt when the temperature is within a certain range, supercooling can be prevented, and the above-mentioned fluctuations in the required cooling time can be eliminated at once. The present invention was completed based on the knowledge that a solidified product can be obtained that is extremely easy to crush. Generally, the sudden generation of crystals due to the addition of seed crystals presupposes supersaturation or supercooling of the object, but in the present invention //i Since extensive supercooling is not required when adding seed crystals, subsequent crystallization will not occur. It is a surprising finding that the process progresses smoothly in a short period of time.

As is clear from the above description, an object of the present invention is to provide an efficient method for producing a crystalline product of guanidine sulfamate of good quality from a melt of the substance. Another object of the present invention is to provide a method for producing guanidine sulfamate that does not require adjusting the properties or cooling conditions of the melt.

The present invention has the following configurations (1) to 5).

(1) Melting and reacting ammonium sulfamate or sulfamino acid and ammonia with dicyandiamide, casting the resulting molten reaction product into a thin layer while maintaining it at 135 to 145°C, cooling the cast product, and solidifying it. 1. A method for cooling and crystallizing a guanidine sulfamate melt, characterized in that seed crystals are previously present on the surface of the cast material, and cooling is then continued.

(2) Casting the molten reactant in a thin layer on a rotating belt,
The cooling crystallization method according to item (1) above, wherein the cast product is cooled through the belt surface.

(3) The cooling crystallization method according to item (1) above, wherein seed crystals are generated by blowing air onto the surface of the thin layered product to cool and vibrate the surface of the product.

(4) The cooling crystallization method according to item (3) above, in which seed crystals are generated at 115 to 100°C.

(5) The belt loaded with the thin-layer cast material or its solidified material is loaded with a liquid or gaseous heat medium at a temperature of 10°C to 55°C as a heat medium for cooling the thin-layer cast material through the belt surface. The cooling crystallization method according to item (2) above, wherein the cooling crystallization method is sprayed onto the back surface of the .

The structure and effects of the present invention will be explained below.

The sulfamic acid molten reaction product used in the present invention is usually produced by the following known methods.

That is, (a) a method in which dicyandiamide, sulfamino acid, and ammonia are subjected to a melt reaction.

A method in which dicyandiamide and ammonium sulfamate are subjected to a melt reaction, or a method in which dicyandiamide and ammonium sulfamate are subjected to a melt reaction in the presence of ammonia.

Of course, the molten reaction product can be used, even if it is produced by an intermediate method of (a) to (c) above or by another method, as long as it is a molten guanidine sulfamate and can be solidified by cooling. The melt is preferably maintained in a storage tank or the like at a temperature of 135 to 145°C for convenience in casting and cooling as described below. If the temperature exceeds 145°C, the quality may deteriorate due to long-term storage, and if the temperature is below 135°C, the viscosity increases and fluidity decreases, making it difficult to cast into a thin layer as described below. There is. The following steps will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a side view of an apparatus for exemplifying the method of the present invention, and FIG. 3 is a plan view thereof.

In both figures or the corresponding figures, 1 is a stainless steel endless belt, 2 is a feeder for supplying a guanidine sulfamino acid melt, and 3 is a feeder for supplying a guanidine sulfamino acid melt (hereinafter referred to as SG) onto the upper surface of the belt. This is a nozzle that blows air onto the melt. Further, 6 is an edge rope 3 to prevent the SG melt on the belt from overflowing to the side. Instead of air, other inert gas such as nitrogen or carbon dioxide may be blown onto the belt 3. The horizontal pipe of the nozzle has small holes at approximately 101 intervals on the side of a single pipe with both ends sealed. The position where air is blown is SG
The average elapsed time is 65-120 seconds after the SG melt is fed onto the belt at about 1-b laterally from the melt feed location.

(When the belt running speed is 58 m/Hr). And S.G.
At a temperature below 115° C., preferably around 110 to 100° C., at which point solidification of the thin layer cast product of the melt occurs, air is blown in order to generate seed crystals and make them present.

The temperature of the air is not particularly limited, but is 0 to 100 DEG C., preferably room temperature to 90 DEG C. The amount of air is such that the surface of the thin layer cast material vibrates. Instead of blowing air, seed crystals may be present by uniformly scattering a small amount of seed crystals on the surface of the cast product before solidification.

In the above embodiment in which air is blown, crystallization immediately occurs due to rapid cooling and vibration. If no air blowing or other means of seed crystal presence is taken, the solidification of the cast product will be delayed by 70 to 120 seconds. Regardless of whether seed crystals are generated or added, the thin layer cast material on the belt is heated at 1o~55°C through the water spray nozzle 4 provided on the back side of the belt.
Cool by spraying with water or warm water. Due to the presence of seed crystals, crystallization progresses rapidly,
The belt is crystallized almost entirely beyond the center of the entire length (6 m) of the upper surface of the belt. Therefore, operations such as adjusting the cooling water temperature are not necessary. The belt is connected to the drive drum 7.
8 and travels at a speed of 58 m/br. The above-mentioned solidified thin layer cast product (hereinafter referred to as the solidified product) is naturally peeled off at the reversing end of the belt, and the doctor-type scraping means commonly used in this type of solidification equipment is unnecessary. , This point is also one of the effects of the method of the present invention.

The solidified material peeled off as described above is supplied to the saw blade type crusher 5 provided at the lower part of the outer side of the belt outlet end, and is crushed. The degree of crushing is adjusted by the interlocking interval and rotational speed of the crusher, but in most cases, re-pulverization or particle size adjustment is necessary, so that the particle size is about 2Qmys to ImW lotus.

The guanidine sulfamate crystallized by the method of the present invention is hard and non-sticky, so even if it is processed using the saw blade type crusher described above, it will not stick to the crushed surface, thus preventing overload operation. There are no unexpected problems.

The present invention will be explained below with reference to Examples and Comparative Examples.

Examples 1 to 3 An apparatus of the type shown in attached FIGS. 2 and 3 was used. The device has a width of 1.277Z and an engine log of 6, so when it is in effect, it is i, om, and the length of the horizontal part is 6 m, a stainless steel endless belt, installed horizontally in the belt width direction provided at the entrance of the belt. It has a melt feeder. While running the endless belt at a speed of 58,712/Hr, the sulfamino acid guanidine melt (140
°C) is continuously fed in a thin layer to the feeder via a metering pump (not shown). The supply amount is 444 kq/Hr.

This melt is uniformly distributed in a thin layer on the upper surface of the belt. The thickness of the solidified thin layer is 3 to 5 thick.

4.2 along the belt running direction on the back side of the belt.
A multi-stage water jet swirling flow nozzle 4 installed over a length of 2 m is used as a nozzle. The guanidine was cooled. Also, air at room temperature was blown through the air nozzle 3 to the melt of guanidine sulfamino acid on the upper surface of the belt to provide cooling and vibration, thereby generating seed crystals. The position is 1.7m from the melt supply position, and the temperature of the melt at this time is 99°C.
Met. Air is blown in an amount that does not scatter the thin layer of melt, and at the same time many crystals are generated and begin to solidify. Solidification is completed at a position where the vehicle has traveled for approximately 30 seconds thereafter. The solidified material eventually peels off naturally from about 1 m from the rear end of the belt. This was crushed using a saw blade type crusher 5, but there was no adhesion to the saw blade even after one week of continuous operation.

In addition, Examples 2 and 3 were carried out in the same manner except that the temperature of the water sprayed from the nozzle 4 onto the back surface of the belt 1 was set to 40°C and 50°C. The results are shown in the table below.

Comparative Examples 1 to 3 Comparative examples 1 to 3 were carried out in the same manner as in the corresponding examples, except that air was not blown onto the belt 1 by a nozzle. In addition to significantly extending the running time until the completion of solidification, each resulted in some adhesion to the crushing surface of the saw blade type crusher. The results are shown in the table below.

Table: Effects of air blowing and cooling water temperature Note A: Air blowing was carried out so that the position + Bi was unclear and unclear. On each side, the solidification start position of the melt was clear, and the time required for assimilation also corresponded to the comparative example. about 60 of
It is short at ~70%.

[Brief explanation of drawings]

FIG. 1 is a temperature one-hour curve related to cooling and solidification of the melt. FIGS. 2 and 3 are a side view and a plan view of an apparatus illustrating the present invention.

Claims (5)

[Claims] (1) Melting and reacting ammonium sulfamate or sulfamino acid and ammonia with dicyandiamide, casting the resulting molten reaction product into a thin layer while maintaining it at 135 to 145°C, cooling the cast product, and solidifying it. 1. A method for cooling and crystallizing a guanidine sulfamino acid molten liquid, characterized in that seed crystals are previously present on the surface of the cast material, and cooling is continued. (2) Casting the molten reactant in a thin layer on a rotating belt,
The cooling crystallization method according to claim 1, wherein the cast material is cooled through the belt surface. (3) Cooling crystallization according to claim (1), in which seed crystals are generated by blowing air onto the surface of the thin-layered cast product to cool and vibrate the surface of the cast product. Method. (4) The cooling crystallization method according to claim (3), in which seed crystals are generated at 115 to 100°C. (5) A liquid or gaseous heat medium of 10°C to 55°C is applied as a heat medium to cool the thin layered product through the belt surface to the back side of the belt loaded with the thin layered product or its solidified product. The cooling crystallization method according to claim (2), wherein the cooling crystallization method is sprayed onto a liquid.