JPS5920652B2 - Method for producing powdered glyoxal - Google Patents

Description

[Detailed description of the invention] Glyoxal has been used in the production of organic chemicals, textile processing,
It is used for various purposes such as paper processing, deodorization, and soil stabilization.

However, when using it, glyoxal is usually commercially available as an aqueous solution with a concentration of about 40%, but powdered glyoxal may be required depending on the application, and if necessary, the powder can be mixed in water. If it is easily converted into an aqueous solution when added to a powder, it has the advantage of reducing transportation and storage costs. Conventionally, various proposals have been made as methods for producing such powdered glyoxal.

For example, (1) a method in which seed crystals are added to an aqueous glyoxal solution and left to stand for a long period of time to precipitate white crystals. (2) A method for obtaining amorphous polyglyoxal hydrate by dehydrating and concentrating an aqueous glyoxal solution. (3) A method in which a powdered inorganic or organic carrier is immersed in an aqueous glyoxal solution and then dried to support glyoxal on the carrier.
etc. can be mentioned.

However, all of these methods have advantages and disadvantages in terms of production and performance of the obtained glyoxal powder.

In other words, in (1), the rate of crystallization of glyoxal is very slow. For example, if polyglyoxal seed crystals are added to a 60% concentration glyoxal aqueous solution and kept at 15°C, about 50% of the theoretical amount of polyglyoxal crystals can be obtained. It takes more than 20 days to complete the process, and it is difficult to say that it is an industrially advantageous method.
Furthermore, since the crystalline glyoxal obtained by this method has poor solubility in water, there are limitations in its use as an aqueous solution. As for (2), as the glyoxal aqueous solution is heated and concentrated, the aqueous solution becomes viscous and eventually becomes a highly sticky cake-like substance, which becomes difficult to stir and concentrate using ordinary equipment. Although the viscous material solidifies when cooled, it adheres to the container and is difficult to remove and furthermore to crush. (3) is a method for which the present applicant has already filed a patent application and is in practical use to some extent, and there are no particular problems in terms of production. There is a problem that the carrier remains as an undissolved substance, and even if the carrier is soluble, the dissolution rate tends to be slow, so there are restrictions depending on the application. As mentioned above, pulverizing glyoxal itself has various problems and has hardly been put to practical use. However, the present inventors have conducted extensive research with the aim of finding a practical method for efficiently producing solid, especially powdered, glyoxal, and further, to obtain powdered glyoxal with excellent water solubility. As a result, the viscosity at 80°C obtained by heating and concentrating the glyoxal aqueous solution was 100
The present invention was completed based on the discovery that the above object can be achieved by applying a shearing force to a viscous material of 00 poise or more.

When concentrating a commercially available 40% glyoxal aqueous solution by heating and stirring under normal pressure or reduced pressure, when the glyoxal concentration reaches about 6070, it becomes a viscous liquid with a viscosity of about 1 poise. When the viscosity reaches about 70%, the viscosity suddenly increases to over 100 poise, making it more sticky and cake-like than fluid. Even if you try to heat it up and stir it to concentrate and dry it, a normal stirrer won't work. It is extremely difficult to further concentrate and solidify the product using normal methods, as it becomes unusable and causes discoloration and deterioration due to heating unless some kind of stirring is performed. However, glyoxal concentrated to this level of concentration will solidify if cooled, but like rice cake, it will stick to the wall of the concentrator and it will be difficult to remove the solidified material.
Even if it were extracted, it would not be easy to crush it. However, when shearing force is applied to the viscous glyoxal that has been concentrated to the extent that it takes on the appearance of a cake-like substance, the cake-like substance gradually loses its adhesive strength and becomes a brittle lump, and when further shearing force is applied, it becomes powdery. It will become. This phenomenon occurs when a shearing force is applied to the glyoxal aqueous solution when it is concentrated and its viscosity at 80°C is 10,000 poise or more.
In a state of 00 poise or less, no powdering or embrittlement phenomenon occurs even if shearing force is applied. There is no particular limit to the magnitude of the shearing force, and it is at least 103 dynes/C! It is sufficient that the force is greater than IL, and the greater the force and the longer the force is applied, the more remarkable the effect will be. However, the properties of the obtained lumps differ depending on the magnitude of the shearing force and the duration of the shearing force. It turns into small lumps and eventually becomes powder. Even if the shearing force is small and the material is in the form of a lump, compared to a lump that is not subjected to shearing force, the stickiness will be reduced and it will be extremely brittle and break easily. It has the advantage of being available.

That is, in the present invention, a lump that can be easily powdered can be obtained by simply applying shearing force to the rice cake having a viscosity above the specific viscosity, and the lump thus obtained can be further continuously subjected to shearing force. By applying the powder, it is easily ground into fine powder and the desired product can be obtained.

In this case, there is a drawback that a fairly strong cutting force is required to crush the lumps, which places a considerable load on the equipment, but the series of steps from dehydration and concentration of the glyoxal aqueous solution to powderization is one continuous process. It has the great advantage of being able to be carried out on an industrial scale, making it extremely useful when carried out on an industrial scale. Furthermore, the present invention is not limited to the case where the powdering is performed in one step as described above, but the lumps to which shearing force has been applied are taken out of the device and mechanically crushed using a crusher. Of course, this is also possible. In this case as well, as mentioned earlier, an extremely large crushing force is required to crush unprecedented lumps due to shear force, but it is possible to obtain a uniform powder with a small crushing force. , its industrial value is very high. As a device for applying shearing force, a seconder, an extruder, a disintegrator, etc. can be used.

The temperature at that time may be room temperature, but it is more preferable to heat it in the range of about 60 to 100°C, and the pressure may be further reduced. The powdered glyoxal obtained by the method of the present invention is a hydrate of amorphous polyglyoxal in which several molecules of glyoxal are associated, and the water content is 15 to 20%. However, since bound water accounts for about 15%, it is a small amount of free water.

Since such powdered glyoxal is a white powder and has low hygroscopicity even when left in the air and has good solubility in water, it is expected that new uses for glyoxal will be developed. Next, the method of the present invention will be explained in more detail by giving examples.

Example 1 A 1-horsepower stainless steel kneader with a charging volume of 51 and two rotary blades and a heating bath has a weight of 40? 2.51<g of glyoxal aqueous solution was charged, kneading was started at a rotational speed of 50 rpm, and dehydration was started while heating the bath to 85°C to 90°C.

The dehydration and concentration process will be explained with reference to FIG. In FIG. 1, 1->- indicates the change over time in the concentration of glyoxal, and 1←(s)- indicates the change in the load of the kneader 1 (change in the current flowing through the ammeter connected to the kneader 1). 3 hours after starting dehydration, glyoxal concentration is 60 weight? become(
4).

At this point, the concentrate has a viscosity of about 1 poise and is in a liquid state. Up until now, the load on the second one has been steady. As the viscosity gradually increased, a burden began to be placed on the secondary, and the glyoxal concentration of the concentrate became 78% by weight, making it cake-like (B). The viscosity at this point is approximately 15000 poise and the applied shear force is approximately 5X105 dynes/CT
It was hot. Dehydration was continued while applying a shearing force to the sample, and when the glyoxal concentration reached 80% and 70% by weight (at 0, the viscosity of the cake-like material reached its maximum point, and at the same time, the load on the second product also reached its maximum value). Further, dehydration was continued while rotating the second cylinder, and when the temperature reached about 8270 a)), the rice cake-like material began to solidify a little and began to break up into small lumps. As a result, the load on the secondary staff also decreased. Furthermore, by the time the point (E) was reached, the above-mentioned small lumps had changed to fine powder, and the load on the kneader had become constant, showing the same value as at the start of dehydration. Glyoxal concentration reached 83 approximately 6 hours after the start of dehydration.
1.2 kg of powdered glyoxal with a weight of 70 and a uniform particle size was obtained. Example 2 The lumps at point (9) in Example 1 were taken out from the secondary, and the lumps were artificially crushed with a hammer.

The lumps were almost completely pulverized within a few minutes, and pulverization was extremely easy. Control example 1 In Example 1, dehydration was performed without rotating the secondary cylinder.
Concentration was carried out.

The change in the concentrate was the same as in Example 1, but at point (B) the concentrate solidified and subsequent dehydration became impossible. Attempts were made to remove the solid material from the container, but it adhered to the wall, requiring a strong force, and could not be removed completely. Example 2 by forcefully removing a part
An attempt was made to artificially crush the solid material using the same method. However, the solid material was extremely hard and could only be broken into small pieces, making it almost impossible to powder it.

[Brief explanation of the drawing]

FIG. 1 is a graph showing changes over time in glyoxal concentration and changes over time in the load applied to the secondary when an aqueous glyoxal solution is dehydrated and concentrated.

Claims (1)

[Claims] 1 Temperature at which glyoxal aqueous solution was concentrated: 80°C
A method for producing powdered glyoxal, which comprises applying a shearing force to a viscous substance having a viscosity of 10,000 poise or more.