JPH06263721A - Production of thiourea dioxide improved in stability and fluidity - Google Patents

Abstract

PURPOSE:To obtain stable thiourea dioxide without lowering the solubility and consolidating even if the fluidity is improved by treating a crystal of the thiourea dioxide with an aqueous solution of a water-soluble polymer such as poval. CONSTITUTION:A crystal of thiourea dioxide, i.e., aminomethanesulfinic acid or formamidinesulfinic acid is treated with an aqueous solution of a water-soluble polymer to improve the stability and fluidity thereof. A method for mixing the aqueous solution of the water-soluble polymer with the crystal of the thiourea dioxide or spraying the aqueous solution thereon with a spray, etc., and then drying the crystal by using the fluidized bed drying or with a vibrating fluidized bed dryer under fluidized conditions or feeding the mixture or sprayed crystal to a granulator and subsequently drying the granulated crystal, etc., is preferred as a treating means. Polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, polyethylene oxide, hydroxypropyl cellulose, methyl cellulose, hydroxyethyl cellulose, dextrin, etc., are cited as the water-soluble polymer. The crystal subjected to this treatment can be prevented from yellowing of form raising the acid content during the preservation thereof.

Description

Detailed Description of the Invention

[0001]

This invention relates to a method of improving the stability and flowability of thiourea dioxide.

[0002]

2. Description of the Related Art Thiourea dioxide (hereinafter referred to as TUD)
Is also referred to as aminomethanesulfinic acid or formamidinesulfinic acid, which is commercially available and can be obtained as a white powder.

[0003] TUD exhibits a reducing property by making its aqueous solution alkaline or heating it, and its reducing power is extremely large.

Therefore, the fields of application thereof include reducing agents for vat dyes, reducing detergents for fibers dyed with disperse dyes, decolorizing agents for fibers dyed with various dyes, can body cleaners for dyeing machines,
Keratin fiber shrinkproofing agent, protein fiber, polyamide fiber and phenol resin fiber bleaching agent, polyacrylonitrile fiber and polyvinyl alcohol fiber manufacturing process decolorizing agent, various dye discharge agents, color discharge agents, dyeing fastness improvement Application to textile industry such as bleaching agent, pulp bleaching agent, antioxidant of organic amine, polymerization catalyst, photographic auxiliary agent for photographic use, one component of detergent, metal ion reducing agent, hydrazone compound of nitro compound belonging to organic compound Alternatively, there are various agents such as reducing agents for amines, reducing agents for secondary alcohols of ketones, reducing agents for primary alcohols of aldehydes, reducing agents for thiols of disulfide.

However, most of the commercially available T
UD has poor fluidity, is easily solidified during storage, requires a soft solution to use, and requires a lot of labor. TUD is a stable compound at room temperature, but it decomposes violently at high temperatures. Sometimes it is decomposed by frictional heat generated during softening work or filling work, and poor fluidity often causes troubles in handling.

[0006] Further, it is known that TUD turns yellow while gradually producing acid during storage. Yellowed TUD
Reduces the reducing power and produces sulfur that is insoluble in acids and alkalis, so it has good fluidity and stable TUD
The demand for is increasing.

As a method for producing TUD, many methods have been reported which are obtained by reacting thiourea and hydrogen peroxide in a solvent. These methods depend on the type of solvent used and a non-aqueous solvent or water. They are roughly classified into solvents, but they are all related to improvement of yield and purity, and few proposals for improvement of stability and fluidity are found. Generally, the larger the particle size, the better the fluidity, but in the case of TUD, T
The solubility of UD is as small as about 3 wt% at room temperature, and it has a drawback that the dissolution rate remarkably decreases as the particle size increases.

The inventors of the present invention have conducted intensive studies on a method for producing a stable TUD in which the dissolution rate does not decrease even if the fluidity is improved and the solidification does not occur. .

[0009]

The present invention is a process for producing TUD having improved stability and fluidity, which comprises treating TUD crystals with an aqueous solution of a water-soluble polymer.

The TUD used in the present invention is not particularly limited, but a wet TUD crystal obtained by deliquoring a TUD slurry obtained through a TUD production process or a dried TUD crystal is usually used.

The present invention treats such TUD crystals with an aqueous solution of a water-soluble polymer. The water-soluble polymer used in the present invention is preferably non-alkaline, and specific examples thereof include polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, synthetic products such as polyethylene oxide, hydroxypropyl cellulose, methyl cellulose, hydroxyethyl cellulose, There are semi-synthetic products such as ethyl cellulose and natural products such as dextrin, cyclodextrin, glucose, maltose, maltotriose, frutotetraose, maltopentaose, maltohexaose, oligosaccharides and starch.

The amount of the water-soluble polymer used is usually 0.05 to 5% by weight, preferably 0.5 to 2% by weight, based on TUD. Too little is not effective, and too much is not economical.

The water-soluble polymer needs to be an aqueous solution at the time of processing. Usually, it is provided as an aqueous solution in advance, but it may be made into an aqueous solution by allowing water to coexist during the treatment.

As a treatment means, an aqueous solution of a water-soluble polymer is mixed with TUD crystals or sprayed with a spray or the like, and then the TUD crystals are dried in a fluidized bed using a fluidized bed dryer or a vibrating fluidized dryer. A method of supplying to a granulator generally used in a granulation technique such as extrusion, rolling, compression, stirring, or tumbling flow and then drying is preferable. A method of spraying in a centrifuge or spraying in a dryer is also preferable.

By such treatment, the proportion of fine crystals of 100 μm or less present in the TUD crystals is reduced, the fluidity is improved without lowering the dissolution rate, and further yellowing and acid content during storage are improved. Stability such as prevention of rise is also improved.

The following are examples of the present invention, which are for illustrative purposes only and are not intended to limit the present invention.

[0017]

[Example] TUD obtained by deliquoring from TUD slurry
An aqueous solution of a water-soluble polymer was mixed with 2.5 kg of wet crystals and then dried in a fluidized bed dryer. The obtained TUD
Table 1 shows the results of measuring the average particle size, the fluidity, the degree of solidification, and the water-soluble stability of the above.

(A) b value: Measured using a colorimetric color difference meter model 1001DP manufactured by Nippon Denshoku Industries Co., Ltd. (COLOR AND COLOR DIFFEREN
A positive value of CE METER) b indicates a yellowish color, and a negative value indicates a bluish color.

(B) For the acid content, take 5 g of the sample and take 50 ml.
Of pure water and methyl red of N / 10 NaOH
Titrated with.

(C) Since TUD is less stable at higher temperatures, it was stored at 50 ° C. as an accelerated test.

(D) The angle of repose is manufactured by Tsutsui Rikagaku Kikai Co., Ltd. B. It was measured using a D powder property measuring device (A.B.D.-72 type).

(E) Sample 20 was packed in a high-density polyethylene bag having a solidification degree of 85 mm × 120 mm and a thickness of 0.2 mm.
0 g was filled and a pressure of 4 t / m ² was applied from the top, and the mixture was left for 3 weeks, and then the solidified sample was cut into 2 cm squares and the hardness was measured (Tsutsui Rikagaku Kiki, Simplified Granule Hardness Tester).

(F) Maltotetraose: Maltotetraose 50%, Maltotriose 8%, Maltose
7%, glucose 2%, maltopentaose 2%,
It consists of 30% oligosaccharide textulin. Run 7-
Maltooligosaccharide No. 12 had glucose 4.4%, maltose 13.4%, maltotriose 7.9%, maltotetraose 7.6%, maltopentaose 7.
6%, maltohexaose + maltoheptaose 4
It consists of 0.0% and 19.1% of other sugars.

(G) PEG of RUN 13 has a degree of polymerization of 2
000, No. The PEG of 14 has a degree of polymerization of 5,000.
Run 15 PVA has a saponification degree of 98.5 ± 0.5 mo
1%, Run 16 has a saponification degree of 88.0 ± 1.5 mol
%, The degree of polymerization is 500.

(H) Run 17 degree of polymerization 2700-75
00, Run 18 is 15,000 to 20,000.

[0026]

[Table 1]

[0027]

[Table 2]

Claims (4)

[Claims] 1. A process for producing thiourea dioxide having improved stability and fluidity, which comprises treating crystals of thiourea dioxide with an aqueous solution of a water-soluble polymer. 2. The method according to claim 1, wherein the amount of the water-soluble polymer used is 0.05 to 5% by weight based on thiourea dioxide. 3. Treatment with an aqueous solution of a water-soluble polymer is carried out by mixing or spraying the aqueous solution with the crystals and drying the crystals in the fluidized state, or after granulation treatment with a granulator and drying. The method according to claim 1 or 2. 4. The water-soluble polymer is polyvinyl alcohol,
Polyethylene glycol, polyvinyl pyrrolidone, polyethylene oxide, hydroxypropyl cellulose,
Methyl cellulose, hydroxyethyl cellulose, ethyl cellulose, dextrin, cyclodextrin,
The method according to any one of claims 1 to 3, wherein the method is selected from the group consisting of glucose, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, oligosaccharides and starch, or two or more thereof.