JPS6259048B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to stable molded products of anhydrous dithionite salts, particularly sodium salts, zinc salts, etc., and a method for producing the same. More specifically, the present invention relates to an anhydrous dithionite molded product characterized by granulating or molding anhydrous dithionite using an organic or inorganic binder and pulverized anhydrous dithionite. An anhydrous dithionite molded product characterized in that the acid salt is mixed with an organic or inorganic binder and a volatile solvent in any order, then granulated or molded, and then the volatile solvent is removed. It is a manufacturing method. Since anhydrous dithionite easily decomposes in aqueous solution and has excellent reducing properties, it is used in fields such as pulp bleaching, butt dye dyeing, and decolorization of azo dye-dyed products. However, the currently commercially available anhydrous dithionite is a fine powder with an average diameter of 0.3 mm or less, so it easily scatters when used, which not only causes a deterioration of the working environment but also disrupts the normal surroundings. It decolorizes dyed products or scatters and mixes with the dye bath, causing poor reproducibility. Furthermore, since it is a fine powder, it easily decomposes due to moisture absorption during storage, which not only significantly deteriorates its reducing power, but also
It is well known that in some cases, sulfur content can spontaneously ignite and cause fires. In addition, especially when bleaching pulp, when such commercially available fine powder is added to a high viscosity pulp slurry, it floats in the upper layer of the pulp slurry and once suspended, it is difficult to settle and dissolve. By the time the solution is prepared, a significant amount of the anhydrous dithionite has decomposed. The amount of decomposed anhydrous dithionite tends to increase as the dissolution temperature increases and the viscosity of the aqueous solution or slurry increases, and 20 to 50% of the added amount decomposes by the time solution preparation is completed. Therefore, the actual situation is that 1.5 to 2.2 times the theoretical amount of anhydrous dithionite is generally used. Solving these problems is a major challenge for the industry, and various measures regarding scattering prevention and stabilization have been proposed to date. For example, Special Publication No. 42-20372, Special Publication No. 42-24651
Special Publication No. 43-24774, Special Publication No. 12013, Special Publication No. 12013, Special Publication No. 8093, Special Publication No. 45-26610, Special Publication No. 1977
−16659, Special Publication No. 34493, Special Publication No. 1977-
No. 34494, Special Publication No. 1973-34495, Special Publication No. 1977-34496
No. 51-17155, etc., all of which include suberic acid, azelaic acid, sebacic acid and their salts, aldehydes, surfactants, aminopolycarboxylic acids, anhydrous sodium bisulfite, alkylene oxides, and fats. Substances such as group amines, oxypropylated starch, oxypropylated cellulose, and glycoses can be simply mixed with anhydrous dithionite, coated on the crystal surface of anhydrous dithionite, or coated with anhydrous dithionite. This method involves reacting with an acid salt to form a stable compound on the crystal surface. That is, the anhydrous dithionite obtained by the methods proposed so far still has an average diameter of 0.3
This product targets fine powders of mm or less in size, and the above-mentioned drawbacks of anhydrous dithionite include scattering during use, decomposition due to moisture absorption during storage, and floating in the upper layer of pulp slurry during pulp bleaching. It is difficult to fundamentally solve this problem, and even today, solving this problem is one of the most urgent challenges in the industry. As a result of intensive research and study, the present inventors found that fine particles or pulverized anhydrous dithionite are granulated or molded using an organic or inorganic binder that is soluble or miscible in volatile solvents and solid at room temperature. The obtained molded product is extremely stable for powder products, and the purpose can be conveniently achieved without the problem of floating that occurs when it is added to a pulp slurry, for example, during pulp bleaching. Moreover, it has been found that problems such as deterioration of the working environment due to dust scattering caused by waste products can be solved all at once. Conventionally, anhydrous dithionite is extremely flammable in the presence of moisture and oxygen, and manufacturing molded products has been thought to be extremely difficult industrially due to the risk of heat accumulation and ignition. It is surprising that the molded article according to the present invention is extremely stable, making its manufacture industrially valuable. Next, a method for producing an anhydrous dithionite molded article of the present invention will be explained. Dithionite anhydride, which is obtained by dissolving or mixing one or more selected organic binders, one or more inorganic binders, or a mixture thereof in one or more volatile solvents, and then pulverized to an average particle size of about 5 μm. Salt and, if necessary, known additives, stabilizers, etc. are added and mixed, and this mixture is tumble-granulated or tablet-molded by a conventional method, and then heated and dried under a nitrogen stream or dried under reduced pressure to make it volatile. A stable molded body can be obtained by removing the solvent. Note that the mixing order may be arbitrary. Examples of the anhydrous dithionite mentioned in the present invention include sodium salts, potassium salts, ammonium salts, zinc salts, etc., and sodium salts or zinc salts are particularly preferably used. Typical volatile solvents used in the present invention include lower alcohols such as methanol and ethanol, and their ethers, acetone, ketones such as methyl ethyl ketone, solvent naphtha, petroleum ether, cyclohexane, benzene, etc. Examples include aliphatic or aromatic hydrocarbons, but are not necessarily limited to these. The mixture of the volatile solvent, anhydrous dithionite and the binder is made into a paste by using the volatile solvent, and then subjected to the granulation or molding process, and after the granulation or molding, the volatile solvent is removed. Can be easily removed. Typical organic or inorganic binders that are solid at room temperature and are soluble or miscible in the volatile solvent referred to in the present invention include tetramethylolmethane, dipentaerythritol, trimethylolpropane, trimethylolethane, and neopentyl. Polyhydric alcohols such as glycol and polyethylene oxide, or monoalcohols such as neopentyl alcohol and stearyl alcohol; Fatty acids or aromatic carboxylic acid ester compounds of these alcohols; Ethers such as aryl ether compounds of these alcohols; Compounds such as formaldehyde sulfoxylate, sodium acetaldehyde sulfoxylate, acetaldehyde ammonia, and urea formalin initial condensate; aldehydes such as glycolaldehyde and 2,4-dioxybenzaldehyde; glycol;
Sugars such as lactose, dextrin, maltose, sucrose;
Urea such as urea, acetylmethylurea, methylurea, phenylurea, thiourea, diethylthiourea, methylthiourea; thioacetamide,
Amides such as acrylamide, azimidotoluene, acetamide, acetamidobenzoic acid, acetamidophenol, butylamide, dicyandiamide, dicyandiamidine, acetylglycine, acetonaphthalide, caprolactam, capronamide; acetaldehyde semicarbazone, acetyl semicarbazide, etc. Carbazones or carbazides; oximes such as acetaldoxime and acetoxime; stearic acid, acetylene dicarboxylic acid, m-acetophenonecarboxylic acid,
Carboxylic acids such as 4-chlorophthalic acid, 2,3-dioxybenzoic acid, 2,6-dioxybenzoic acid, 4,5-dioxyphthalic acid; 1,3-dioxynaphthalic acid, 1,7-dioxynaphthalic acid,
Naphthalenes such as 2,7-dioxynaphthalene; polymer compounds such as methylcellulose, ethylcellulose, butylcellulose; and other 1,3
-cyclohexanedione, 1,6-hexanediol, tetraoxybenzene, trioxyacetophenones, etc., but are not necessarily limited to these. Typical inorganic binders include sodium borohydride, imidobisulfonylamide ammonium chloride, potassium hydroxide, sodium hydroxide, and sodium hydrogen carbonate, but these are not necessarily the only ones. Not limited. The amount of binder added may be any amount depending on the purpose, but it is preferably 1 part or more per 100 parts of anhydrous dithionite itself or anhydrous dithionite to which a stabilizer has been added. more than 10 parts, more preferably 10 parts
It is more than 100%. The greater the amount added, the greater the stability under humid conditions, but too much is not preferred from an economic standpoint. Therefore, it is generally used in a range of 5 to 30 parts. Depending on the type of binder, if the solubility in volatile solvents is low and it is impossible to add the prescribed amount, a method is to mix and granulate while drying and dropping a volatile solvent in which the binder has been dissolved. Adopt. or,
In some cases, the binder and anhydrous dithionite may be mixed in powder form. The mixing ratio of the volatile solution containing the binder to the anhydrous dithionite itself or the anhydrous dithionite to which a stabilizer has been added is determined by the particle size of the anhydrous dithionite, sodium carbonate, nitrite, It varies depending on the presence or absence of a stabilizer such as sodium tripolyphosphate, and is determined by taking into consideration the optimum conditions for granulation and molding, but the present invention is not limited thereto. The shape of the anhydrous dithionite molded product of the present invention may be arbitrary, but from the viewpoint of handling, it is preferably spherical or granular, and the diameter is 1 mm or more, preferably 3 mm or more, and more preferably 3 mm or more when expressed as an average diameter. Those with a diameter of 5 mm or more exhibit excellent stability. The anhydrous dithionite molded product according to the present invention is not only extremely stable even when left in the air, but also
When added to viscous liquids such as pulp slurry and waste sludge, it does not float in the upper layer, making it possible to extremely reduce the amount of anhydrous dithionite decomposed. In addition, since it is a molded product and has high strength, there is no need to worry about dust, and it is extremely good in terms of pollution. Another feature of the anhydrous dithionite molded product of the present invention is that when it is dissolved in water, it gradually dissolves from the surface, so it takes a long time to exhibit the necessary reduction potential. Commercially available anhydrous dithionite salts are fine particles, so they dissolve all at once and are extremely easy to decompose, so they have the disadvantage that the time required to exhibit the required reduction potential is shortened as a result. It must be said that the use of the anhydrous dithionite molded product according to the present invention is extremely economical since the same effect can be achieved with a smaller amount added. In other words, the anhydrous dithionite molded product according to the present invention solves all the problems of the existing fine powder products mentioned above, and is extremely useful in industrial fields such as pulp bleaching, butt dyeing, and decolorizing dyed materials. It is valuable and useful. The present invention will be specifically explained below with reference to Examples, but the present invention is not limited by these. [Example 1] Anhydrous sodium dithionite powder (purity: 90.4
%, particle size: 100 mesh all-through) was sufficiently ground in a mortar to pulverize it to 5μ or less, and then mixed with 15 parts of methanol and 20 parts of the various binders shown in Table 1.
A solution obtained by dissolving or mixing these parts was added and mixed. This was granulated in a nitrogen atmosphere using a rolling granulator until it became spherical with an average particle size of 15 to 20 mm.
The mixture was dried for 3 hours to obtain an anhydrous sodium dithionite molded product. Put 30g of this anhydrous sodium dithionite molded body into a 100ml beaker with an inner diameter of 55mmφ,
The sample was left in the air under the same conditions to measure the change in purity of anhydrous sodium dithionite over time. For comparison, similar measurements were made on anhydrous sodium dithionite powder and simply dried powder before granulation after addition of a binder. The results are shown in Table 1. However, the numbers in parentheses indicate the decomposition rate (%). Urea only versus methanol
13 parts were dissolved.

[Table] As shown in Table 1, it was confirmed that the molded product according to the present invention was significantly more stable than the powder product. The stability in an aqueous solution is shown in the usage example below. (Usage example 1) Put 500g of 5% pulp slurry into a 1000ml beaker and use a two-bladed blade with a length of 45mm and a width of 20mm.
The mixture was stirred at a speed of 20 rpm and heated to 60°C.
30 g of anhydrous sodium dithionite molded article (purity: 76.4%) of Example-1 No. 4 was added to this. As a result, the entire amount settled as soon as it was added and did not float. In addition, anhydrous sodium dithionite powder (purity
25.4 g of 90.4% particle size 100 mesh all-through) was added. As a result, about 40% of the sample floated and it took about 2 minutes for it to completely settle. In addition, changes over time were measured at the same time as the addition. Table 2 shows the change in anhydrous sodium dithionite concentration over time.

[Table] As shown in Table 2, it was confirmed that the stability of the molded product according to the present invention in an aqueous solution was significantly superior to that of a powder product. Furthermore, it was confirmed that the molded article according to the present invention quickly settled in the pulp slurry, gradually dissolved and decomposed, and the anhydrous sodium dithionite introduced into the pulp slurry was effectively utilized. (Usage example 2) Add 40 parts of refined ground pulp (dry equivalent) to 960 parts of water and heat while stirring gently to raise the temperature to 60℃. Next, 0.4 part of the anhydrous sodium dithionite molded product obtained in Example-[] No. 4 was added,
Process for 30 minutes at a temperature of 60 °C. Next, the paper was made into gauze paper using TAPPI standard circular gauze stock, and Hunter whiteness was measured using a Color Difference Nata to obtain paper having a whiteness of 49 Hunter whiteness points. (Average value of 3 tests) For comparison, 0.4 part of powdered anhydrous sodium dithionite (purity 85%) was used instead of the anhydrous sodium dithionite molded product of Example No. 4. As shown in Table 5, the molded product of the present invention obtained good results in terms of whiteness. In addition, it was found that the powder product partially floats in the upper layer of the pulp slurry and takes time to dissolve inside the slurry, but the molded product of the present invention immediately settles in the pulp slurry and can be effectively utilized. .

[Example 2]

Anhydrous sodium dithionite powder (purity: 90:
4%, particle size: 100 mesh all-through) was added with the reagent sodium carbonate to obtain a product with a purity of 86.7%. Sodium tripolyphosphate 4.5 to 91.7 parts of this
and 3.8 parts of urotropin were added to make 100 parts, thoroughly ground in a mortar to a size of 5μ or less, treated with a binder in the same manner as in Example 1 to form a molded body, and similarly aged. It was measured. For comparison, changes over time were also measured for the powder before it was crushed in a mortar. The results are shown in Table 3. However, the numbers in parentheses indicate the decomposition rate (%).

[Example 3]

Anhydrous sodium dithionite powder (purity: 90.4
%, particle size: 100 mesh all through) 100 parts methanol and trimethylolpropane content is 4th
As shown in the table, 30 parts of the solution was prepared and mixed, compressed into tablets at a pressure of 30Kg/ ^cm2 , and then heated at 50℃ for 10 minutes.
Dry under reduced pressure for 2 hours at mmHg, diameter 15mmφ, thickness 7.
A disc-shaped anhydrous sodium dithionite molded body of mm size was obtained. Changes over time of this anhydrous sodium dithionite molded body were measured by the method of Example-1. For comparison, the change over time of anhydrous sodium dithionite powder was also measured in the same manner. The results are shown in Table 4. However, the numbers in parentheses indicate the decomposition rate (%).

[Example 5]

In place of the binder used in Example-1, ethyl cellulose or butyl cellulose was used for 2 hours each.
A stable molded anhydrous sodium dithionite was obtained in the same manner as in Example 1 except that 33 parts of ethanol was used instead of methanol. [Example 6] Instead of the binder used in Example-1, acetaldehyde ammonia, 2 parts sodium borohydride, 1 part sodium hydroxide, 25 parts trimethylolethane, and dithionite anhydride were used. A stable molded anhydrous sodium dithionite was obtained in the same manner as in Example 1 except that 90 parts of sodium was used. [Example 7] Anhydrous sodium dithionite powder (purity: 90.4
%, particle size: 100 mesh all-through), 12 parts of crushed sodium formaldehyde sulfoxylate, 5 parts of sodium tripolyphosphate, and 3 parts of sodium carbonate were gently stirred in a Nauta mixer. Prepare a homogeneous powder mixture. Next, 10 parts of methanol and 10 parts of ethanol are added and mixed by gentle stirring to form a paste. This paste-like composition was molded into tablets at a pressure of 30 kg/cm ² , and then the volatile solvent was removed in a vacuum dryer to obtain stable molded anhydrous sodium dithionite (particle size: 3 mm). In addition, by changing the tablet shape, it was possible to form molded products of arbitrary particle size and shape, such as spherical or fruit-like shapes. Using the obtained molded anhydrous sodium dithionite, Nihonsuren Blue BC was prepared in the usual manner.
Daspoused powder (butt dye manufactured by Sumitomo Chemical)
CI, Vat Blue 6) was able to be dyed into a bright blue color on cotton fabric with good reproducibility. [Example 8] Polyoxyethylene nonyl phenyl ether (number of moles added: 50) was used instead of sodium formaldehyde sulfoxylate used in Example-7.
1 part, polyoxyethylene phthalate ester (additional mole number 50) 1 part, trimethylolethane 6
A stable molded anhydrous sodium dithionite was obtained in the same manner as in Example 7 except that 1 part and 4 parts of dicyandiamidine were used. [Example 9] Example 7 except that anhydrous zinc dithionite or anhydrous potassium dithionite was used instead of the anhydrous sodium dithionite used in Example 7.
A stable molded body of anhydrous zinc dithionite or anhydrous potassium dithionite was obtained in the same manner as described above. [Example 10] In place of the polyoxyethylene nonyl phenyl ether used in Example-8, 1 part of 1,3-dioxynaphthalene was used, and in place of the polyoxyethylene phthalate ester, 2,6-dioxy A stable molded anhydrous sodium dithionite was obtained in the same manner as in Example 8 except that 1 part of benzoic acid and 4 parts of acetaldehyde semicarbazone were used in place of dicyandiamidine. [Example 11] Anhydrous potassium dithionite powder (purity: 90.4
%, particle size: 100 mesh all-through), 2 parts of polyethylene glycol (number of moles added: 50), 18 parts of neopentyl glycol, and 5 parts of sodium tripolyphosphate are mixed in a Nauta mixer. Next, 30 parts of methanol was added to form a paste, which was then molded to a particle size of 20 mm using a tableting method. Next, methanol was removed in a vacuum dryer to obtain a stable molded anhydrous potassium dithionite. [Example 12] A stable molded anhydrous potassium dithionite was obtained in the same manner as in Example 11 except that lactose or maltose was used instead of the binder used in Example 11. . [Example 13] Anhydrous ammonium dithionite powder (purity:
90.4%, particle size: 100 mesh all through) 80
1 part of ethyl cellulose, 14 parts of trimethylolpropane, 2 parts of ammonium chloride, and 3 parts of sodium tripolyphosphate are gently stirred in a Nauta mixer to prepare a uniform powder mixture. Next, add 25 parts of ethanol and mix gently to form a paste. This paste composition was molded into tablets in the same manner as in Example 3, and then ethanol was removed in a vacuum dryer to obtain a stable anhydrous ammonium dithionite molded product. [Example 14] Instead of the binder used in Example-13, 1,6-
A stable molded product of anhydrous ammonium dithionite was obtained in the same manner as in Example 13 except that hexanediol or tetraoxybenzene was used.

Claims (1)

[Scope of Claims] 1. An anhydrous dithionite which is produced by granulating or molding anhydrous dithionite using an organic or inorganic binder that is soluble or miscible in a volatile solvent and solid at room temperature. Dithionite molded body. 2. The molded article according to claim 1, wherein the average diameter of the molded article is 1 mm or more. 3. Pulverized anhydrous dithionite, an organic or inorganic binder that is soluble or miscible in a volatile solvent and solid at room temperature, and a volatile solvent are mixed in any order, and then granulated or molded. 1. A method for producing an anhydrous dithionite molded product, which comprises removing the volatile solvent after the reaction.