JP2843047B2 - Hollow sphere made of sodium sulfate and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention comprises, for example, sodium sulfate, which can adsorb and saturate a liquid composition of various organic compounds in a large amount, or can be applied as a builder to a granular synthetic detergent composition. The present invention relates to a hollow spherical body and a method for producing the same.

(Prior Art) Conventionally, inorganic particles having a honeycomb structure have been known as a substrate that absorbs and saturates organic substances such as detergents, baths, disinfectants, disinfectants, and agricultural chemicals. For example, U.S. Pat.No. 4,547,352
The specification discloses that a solvent is further sprayed and locally dissolved on a porous granule produced by rapidly expanding a borax pentahydrate particle at a temperature equal to or higher than its melting point, thereby forming fine voids in the granule. It has been proposed that the pores are communicated with each other to form a network, thereby increasing the ability to absorb and saturate organic substances and the like. Although this method is effective for improving the adsorptivity, it requires a number of careful steps and is inevitably disadvantageous industrially. In addition, in Japan, boron resources such as borax are extremely scarce and not only rely almost entirely on imports, but also similar boron-based baths are being voluntarily regulated in the United States for health reasons. At times, there is a need to develop a replacement for Borax.

On the other hand, granules of sodium silicate or sodium sulphate, which are resource-rich and harmless for health and hygiene and environmental protection, have been conventionally put to practical use, especially for mixing with granular synthetic cleaning compositions, and there are many related proposals. There is. For example, JP-A-48-15798 discloses a dilute solution of sodium silicate (4
(0% or less) by spray-drying, which indicates that hollow spherical particles can be obtained, and in order to eliminate defects such as easy disintegration of such particles, a plurality of small particles are aggregated. It proposes to be granular sodium silicate. As described in this proposal, conventionally known hollow spherical particles produced by simply spray-drying a sodium silicate solution that is dilute enough to be spray-dried have various practical difficulties, and a special process is required to solve them. And modification of the shape.

Further, with respect to sodium sulfate, a method using sodium silicate as a binder has been proposed in order to convert the high-density, small-particle size powder into a useful low-bulk-density, large-particle aggregate. 49-96992, the granules obtained by spray drying sodium sulfate discharged from the production process of synthetic aliphatic acids, further passed through a foamed layer of a surfactant-containing aqueous sodium sulfate solution. Attempts to improve particle size have been made by Soviet Patent 1,125,192 (Chemical Abstracts,
102: 134377m). However, these prior arts all disclose a complicated process for obtaining sodium sulfate granules having a small bulk density and a large particle size, and suggest hollow spherical particles of sodium sulfate or a method for producing the same. Absent.

(Problems to be Solved by the Invention) The present inventor has been conducting research on the effective activity of sodium sulfate produced as a by-product in large quantities from the viscose rayon and caprolactam production processes and the like and discharged as a titanium dioxide production process waste liquid. The present invention has been completed as a result of intensive studies, focusing on the possibility of a substitute for borax.

That is, an object of the present invention is to provide a hollow spherical body of sodium sulfate having a relatively large particle size and a relatively small bulk density and exhibiting an increased oil absorbing ability.

Another object is to provide an economically advantageous and simple method for producing such hollow spheres.

Another object is to provide an easy-to-handle powder which is made of organic liquids such as various chemicals and agricultural chemicals adsorbed and saturated.

Yet another object is to mix with the granular detergent composition,
It is an object of the present invention to provide sodium sulfate hollow spheres which are not easily separated.

Still another object is to make effective use of sodium sulfate, which is a by-product or effluent of various manufacturing processes.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a substantially anhydrous microporous solid shell containing sodium sulfate as a main component and containing 0.05 to 1.5% by weight of a surfactant. A hollow sphere made of sodium sulfate, characterized by having an average outer diameter of 100 to 500 μm and an effective pore volume of at least 0.5, and having a surface activity of 40 to 70% by weight of sodium sulfate 0.025-0.8
% Aqueous solution comprising at least 35 ° C
This is a method for producing a hollow spherical body made of sodium sulfate, which is characterized by spraying into a high-temperature air stream at a temperature of 300 to 450 ° C. after dehydration and drying.

 Hereinafter, the configuration of the present invention will be described in detail.

Sodium sulfate, Na ₂ suitable for the above method of the present invention
SO ₄ , whose purity is preferably 98% or more, more preferably 99% or more.
% Or more, so-called neutral anhydrous sodium sulfate powder. When a commercially available sodium sulfate powder having a large average particle size is used, it is more commonly used in the method of the present invention.
About 200 mesh pass (particle size of about 80 μm or less), preferably pulverized to about 250 mesh pass (particle size of about 60 μm or less) is poured into water with stirring to obtain a concentration of 40 to 70% by weight.
Preferably, it is 42 to 66% by weight of a homogeneous viscous aqueous slurry. If a particle size larger than the above is used, it is difficult to obtain a slurry which is sufficiently uniform and viscous and stable. On the other hand, if the slurry concentration is too low outside the above range, a large amount of heat is required for evaporating and removing water in the next spray drying step, which is not only uneconomical, but also the outer shell of the hollow sphere to be formed becomes thin. This is not preferable because the strength of the sphere is insufficient. On the other hand, if the concentration is too high, atomization by spraying from the nozzle becomes difficult, so it should be avoided.

In order to prevent sedimentation and separation of such a high-concentration slurry and keep the suspension phase more stable, an appropriate amount of any known suspending agent, for example, bentonite, can be added as necessary. The addition amount is usually 0.3 to 0.6% by weight, preferably
It is in the range of 0.35 to 0.55% by weight. When the amount is too small, the effect of stabilizing the slurry is insufficient. On the other hand, when the amount is too large, impurities remain in the product in a large amount, which may affect the quality, so that all are unsuitable.

In the method of the present invention, the slurry further contains an appropriate amount of a surfactant. As the surfactant, known anionic, nonionic, cationic or amphoteric surfactants can be applied as appropriate, and anionic or nonionic surfactants are particularly suitable. The suitable amount of the additive is usually 0.025 to 0.8% by weight, preferably 0.05 to 0.5% by weight in terms of the active ingredient.
%, More preferably in the range of 0.1 to 0.25% by weight. In the present invention, the surfactant controls an important function as described below. The optimum amount of the surfactant is, of course, affected by the type of the surfactant, but if the added amount is less than the above, a sufficient effect is obtained. Is difficult to exert, and there is a concern that a decrease in the bulk density and an increase in the particle size of the formed sphere may not be achieved. Further, even if it is increased beyond the above range, the effect is not substantially changed, and therefore it should be avoided from an economic viewpoint.

The aqueous slurry of sodium sulfate thus prepared has a viscosity of at least 100 cps as measured by a B-type viscometer at 12 rotations and 70 ° C.

Next, the slurry is subjected to a spray drying process. Sodium sulphate has a critical temperature of 32.5 at which the transition from anhydrous to decahydrate occurs.
Because of the ° C, the sodium sulfate slurry is preheated to at least 35 ° C, preferably at least 40 ° C, prior to being subjected to the spray-drying step to prevent conversion to the decahydrate. This preheating prevents the phase separation of the slurry, lowers the viscosity appropriately, helps atomize the slurry in the spray drying step, and facilitates dehydration and drying with a high-temperature air stream.

The preheated slurry is sprayed from a nozzle into a high-temperature air stream heated to an inlet temperature of 300 to 450 ° C., preferably 350 to 400 ° C., and dehydrated and dried using a known and commonly used spray dryer. Suitable operating conditions for efficiently obtaining hollow spheres having a sufficiently large particle size and a small bulk density include a one-fluid spray nozzle having an orifice diameter of 1.0 to 1.4 mm and a pressure of 7 to 20.
It is advisable to spray at a rate of kg / cm ² and a supply amount of 60 to 100 kg / hr, and adjust the flow rate appropriately so as to maintain the outlet temperature at least 120 ° C.

If the inlet temperature of the heated air flow is too high, the slurry mist drops may explode and do not form hollow spheres, while if it is too low, drying becomes insufficient, and the slurry adheres to the vessel wall or agglomerates between the spheres (agglomeration). ), Which does not meet the purpose of the present invention.

The product obtained by the method according to the invention consists of at least 98% by weight, preferably 99% by weight, of sodium sulphate and has a solids content of 0.05 to 1.5% by weight, preferably 0.1 to 1.5% by weight.
Hollow spheres comprising 1.0% by weight, more preferably 0.2-0.5% by weight of a surfactant and optionally a small amount of a suspending agent, respectively, each having a solid component and a substantially anhydrous microporous solid shell. Mainly the body. The hollow sphere has an average outer diameter of 100 to 500 μm, preferably 140 to 400 μm, more preferably 150 to 300 μm, and the outer shell has a thickness of about 2 to 10 μm. Microscopic observation confirmed that a large number of micropores on the order of angstrom to nonameter penetrated the outer shell. It should be understood that “substantially anhydrous” means that a slight amount of water in the atmosphere is absorbed and a water content that does not impair the performance of the product is acceptable.

In the present invention, the basic structure of such a micro hollow sphere is as described above, but due to subtle condition fluctuations in the manufacturing process, a hollow sphere or a small number of fine pieces with a smaller diameter are built in the hollow sphere. Things can be generated or mixed. These transformation products are also within the scope of the present invention as long as they have a hollow spherical shell and have an equivalent function.

(Operation) The present invention has the above-mentioned constitution, and in the method of the present invention, high-concentration uniform and stable slurry can be prepared because sodium sulphate pulverized into fine powder is used as a raw material. When a suspending agent is used, its stability is further increased. Such a high-concentration slurry greatly reduces the amount of heat required for drying and dewatering, and is extremely economically advantageous. Further, even at a high temperature, even if the viscosity is high, the viscosity is appropriately reduced by preheating, and the atomization becomes easy. The mist droplets are rapidly dehydrated from the outer peripheral surface by being exposed to a high-temperature airflow at a specific temperature, and the water inside the mist droplets also moves to the peripheral surface sequentially and evaporates through the outer periphery. The mechanism and behavior of the surfactant applied to the method of the present invention are not completely clear, but are presumed as follows. That is, as a result of the surfactant decreasing the surface tension of the mist droplet, the mist droplet easily expands due to the increase of the internal pressure due to the vaporization of the internal moisture, and dehydration and solidification proceeds. Because the outer shell during solidification still has a low surface tension, it does not show high resistance to water vapor penetration and dehydration, and therefore does not explode, and the water vapor on the inner surface forms numerous micropores in the outer shell. I do. Thus, a microporous spherical outer shell is formed, and sodium sulfate inside migrates in the centrifugal direction and deposits on the inner surface of the outer shell to form a hollow spherical body having a relatively large wall thickness. It is.

(Effect of the Invention) The product according to the present invention thus obtained is 100 to 500
It is a hollow sphere having a relatively large average outer diameter of μm, and is composed of a microporous outer shell.
Since it shows an increased effective pore volume of 0.5 and uniformly contains a surfactant, it shows excellent affinity for both organic liquids and inorganic liquids. Therefore, organic liquids, such as various chemicals such as detergents, surfactants, disinfectants and disinfectants, herbicides, liquid fertilizers, pesticides such as insect repellents, and difficult-to-handle liquids such as mineral oil, are well adsorbed and saturated, and the granular state is reduced. It is useful as a carrier for carrying out. This adsorption / saturation ability was determined in accordance with JIS K 5101-1978 (pigment test method), paragraph 19, the method of measuring the amount of oil absorption, and using PEG400 instead of oil for boiling as follows.

Oil absorption: 3 g of a sample is placed on a glass plate (approximately 250 x 250 x 5 mm), and PEG400 (polyethylene glycol having an average molecular weight of 400, manufactured by Wako Pure Chemical Industries, Ltd.) is dropped from the burette into the center of the sample little by little. Knead well. Repeat the operation of dripping and coating, the whole becomes a hard putty-like lump for the first time, and the end point is when it is rolled up in a spiral shape with a steel spatula, the amount of PEG 400 used up to that point is determined, Oil absorption by the following formula (%)
Calculate G.

Here, H: amount of PEG400 (ml) S: weight of sample (g) The sodium sulfate hollow spheres according to the present invention exhibit an oil absorption of at least 35%, preferably at least 40%.

The effective pore volume which seems to correlate with the oil absorption means a volume per unit volume of the sample capable of absorbing the liquid, and is a value measured as follows.

Effective pore volume: Transfer about 50 cc of sample to a 200 cc graduated cylinder and read the exact volume. 50cc of dehydrated isopropyl alcohol
Weigh and add to it. Use this measuring cylinder for approximately 7.
Place it in an ultrasonic cleaner (45 kHz) with water in a water tank up to a height of 5 cm, apply ultrasonic waves for 30 seconds, and then repeat the operation of leaving for 1 minute to deaerate three times, Read the total volume in the graduated cylinder. The effective pore volume (cc / cc) is determined by the following equation.

The sodium sulfate hollow spherical body according to the present invention is at least 0.5, preferably at least 0.5, in combination with being hollow as described above and having a microporous outer shell.
6, more preferably having an effective pore volume of at least 0.7.

On the other hand, the sodium sulfate hollow spheres according to the present invention are also useful for mixing as a buffer or anti-caking agent into the granular synthetic detergent composition, and have a special shape and a low bulk specific gravity close to that of the granular synthetic detergent. For this reason, the surfactants contained in the hollow spheres of the present invention are readily soluble in water, and dissolve instantaneously and have a cleaning effect, as well as detergents, without becoming easily compatible with granular synthetic detergents and easily causing laminar separation. It also has the effect of promoting.

Furthermore, the hollow spherical body according to the present invention has an appropriate strength by an outer shell having an appropriate thickness, and the weakness due to the thin wall thickness of a known hollow spherical body usually manufactured by spray drying is improved, Does not collapse easily during storage or transportation.

According to the present invention, the way of effectively utilizing sodium sulfate produced as a by-product or discharged in various production processes is pioneered, and industrial contribution is great.

(Examples) Hereinafter, the present invention will be further described by examples. In Examples, “%” and “parts” are “% by weight” unless otherwise specified.
And "parts by weight".

Example 1 Neutral anhydrous sodium sulfate (Mitajiri Chemical Industry) having a purity of 99.8%, a pH of 7, and a particle size of 250 mesh was used as sodium sulfate. As a surfactant, Marpomerse OT (trade name of dialkyl sulfosuccinate anionic surfactant, manufactured by Matsumoto Yushi Seiyaku Co., Ltd., active ingredient 70%), and as a suspending agent, bentonite "Asama Ink" (Toyojun Yoko Sales, solid content (92%) using the following formulation.

Pure content conversion% Glauber's salt 50.0 parts 52.67 Marpomase OT 0.27〃 0.20 Bentonite 0.47〃 0.46 Water 44.0 〃 46.67 94.74 parts 100.00 The mixture was heated to 67 ° C. with further stirring,
A uniform and stable slurry having a viscosity of 225 cps was obtained. A vertical spray dryer of the type that supplies hot air from above and sprays the stock solution to be dehydrated upward from the lower nozzle: Niro Atomizer SD
10 kg / cm ² of the above slurry in a -12.5-N type nozzle type spray dryer (manufactured by Ashizawa Niro Atomizer).
80 from one fluid nozzle with an orifice diameter of 1.4 mm at supply pressure of
Spraying was performed with a feed rate of 9090 kg / hr. The inlet temperature of the hot air was controlled at 400 to 380 ° C, and the flow rate was such that the outlet temperature was maintained at 160 ° C.

The dried particles collected from the bottom of the dryer tower have the maximum particle size
300-440μm hollow sphere, with many fine holes penetrating the outer shell, average particle size 220μm, bulk density 0.57-0.55g
/ cc, effective pore volume 0.712 ~ 0.722, oil absorption 42% (cc / g). Microscopic observation confirmed that the outer shell had a wall thickness of about 4 to 9 μm. Analysis of the hollow spheres produced revealed that they had a composition of 98.77% sodium sulfate, 0.38% surfactant and 0.85% bentonite.

Example 2 An aqueous slurry having a viscosity of 150 cps was prepared by the following formulation using the same sodium sulfate, surfactant and suspending agent as in Example 1 above.

Purified content % Glauber's salt 58.58 Marpomase OT 0.20 Bentonite 0.45 This slurry was heated to 50 ° C., and dried and dehydrated using the same spray dryer as described in Example 1 under the following conditions.

One-fluid nozzle, orifice diameter 1.2 mm Slurry supply pressure 7-10 kg / cm ² Liquid supply amount 70 kg / hr Hot air inlet temperature 350 ° C Hot air outlet temperature 125-150 ° C The properties and analysis values of the obtained hollow spherical bodies are as follows: Met.

Maximum particle size 300 ~ 400μm Average particle size 150 ~ 200μm Bulk density 0.58 ~ 0.64g / cc Wall thickness 3 ~ 8μm Effective pore volume 0.723 ~ 0.725 Oil absorption 40% (cc / g) Analysis value: Sodium sulfate 98.78% Surface activity Agent 0.35% Bentonite 0.87% Example 3 An aqueous slurry having a viscosity of 150 cps was prepared by the following formulation using the same sodium sulfate, surfactant and suspending agent as in Example 1 above.

Purified content% Glauber's salt 63.43 Marpomase OT 0.22 Bentonite 0.49 This slurry was heated to 45 ° C., and dried and dehydrated under the following conditions using the same spray dryer as described in Example 1.

One-fluid nozzle, orifice diameter 1.2 mm Slurry supply pressure 8 to 10 kg / cm ² Liquid supply amount 75 kg / hr Hot air inlet temperature 400 to 350 ° C Hot air outlet temperature 160 ° C The properties of the obtained hollow spheres were as follows: .

Maximum particle size 400 μm Average particle size 200 μm Bulk density 0.72 to 0.69 g / cc Wall thickness 4 to 8 μm Example 4 The same formulation as in Example 1 was used, but with a viscosity of 350 cps by the following formulation using sodium sulfate, a surfactant and a suspending agent. An aqueous slurry was prepared.

Pure content% Glauber's salt 65.33 Marpomase OT 0.91 Bentonite 0.45 This slurry was preheated to 44 ° C., and dried and dehydrated under the following conditions using the same spray dryer as described in Example 1.

One-fluid nozzle, orifice diameter 1.2 mm Slurry supply pressure 10-15 kg / cm ² Liquid supply amount 65-100 kg / hr Hot air inlet temperature 350-450 ° C Hot air outlet temperature 160-210 ° C The properties of the obtained hollow spheres are as follows. It was right.

Maximum particle size 300 ~ 430μm Average particle size 190μm Bulk density 0.77 ~ 0.688g / cc Effective pore volume 0.650 ~ 0.692 Wall thickness 5 ~ 10μm Example 5 After preheating the same slurry used in Example 1 to 70 ° C, Spray dryer: Dehydrated and dried using a DC-225G nozzle type spray dryer (manufactured by Okawara Koki) under the following conditions.

One-fluid nozzle, orifice diameter 1.2 mm Slurry supply pressure 10-20 kg / cm ² Liquid supply amount 65-75 kg / hr Hot air inlet temperature 350 ° C Hot air outlet temperature 168-180 ° C The properties of the obtained hollow spheres are as follows. there were.

Maximum particle size 300 to 440 μm Average particle size 190 μm Bulk density 0.43 g / cc Effective pore volume 0.724 Wall thickness 3 to 9 μm Oil absorption 40% (cc / g) Example 6 Same as the above Example 1, glaubrite and surfactant An aqueous slurry having a viscosity of 125 cps was prepared according to the following formulation using a suspension and a suspending agent.

Pure content% Glauber's salt 42.93 Marpomase OT 0.16 Bentonite 0.37 After preheating this slurry to 70 ° C., it was dried and dehydrated by the spray drier used in Example 5 under the following conditions.

One-fluid nozzle, orifice diameter 1.2 mm Slurry supply pressure 10 kg / cm ² Liquid supply amount 75 kg / hr Hot air inlet temperature 350 ° C Hot air outlet temperature 166 ° C The properties of the obtained hollow spherical body were as follows.

Maximum particle size 340μm Average particle size 170μm Bulk density 0.27g / cc Effective pore volume 0.833 Wall thickness 4-8μm Oil absorption 44% (cc / g) Comparative Example 1 99.8% pure as sodium sulfate, pH7, average particle size 218μ
m neutral anhydrous sodium sulfate (Mitajiri Chemical Industry Co., Ltd.), dissolve in water with stirring, and add Na ₂ S
A saturated solution of 32% O ₄ and 2.3 cps viscosity was prepared. 60 ℃
After being preheated to the above temperature, the spray dryer used in Example 1 was used for dehydration and drying under the following conditions using a two-fluid nozzle.

Nozzle air pressure 1.0 to 1.5 kg / cm ² Fluid pressure 1.0 to 1.2 kg / cm ² Liquid supply 9 kg / hr Hot air inlet temperature 290 ° C Hot air outlet temperature 130 ° C The properties of the obtained hollow spheres are as follows. Was.

Maximum particle size 180μm Average particle size 90μm Bulk density 0.25g / cc Effective pore volume 0.748 Wall thickness 1-4μm As described above, in this experiment, the fragile hollow sphere with small particle size and thin wall thickness and extremely low bulk density Thus, a mixture of a large amount of fine powder in which the powder collapsed was obtained, and the hollow sphere was easily crushed by ultrasonic waves when measuring the effective pore volume.

Comparative Example 2 The sodium sulfate used in Comparative Example 1 was pulverized with a ball mill to a particle size of 250 mesh pass, and added to water with stirring without adding a surfactant or the like to prepare an aqueous slurry having a concentration of 53% and a viscosity of 350 cps. did. This was preheated to 44 ° C., and then dewatered and dried by the spray dryer used in Example 1 using a two-fluid nozzle under the following conditions.

Nozzle air pressure 1.0 to 1.5 kg / cm ² Fluid pressure 1.0 kg / cm ² Liquid supply 5 kg / hr Hot air inlet temperature 290 ° C Hot air outlet temperature 130 ° C The properties of the obtained hollow spherical body were as follows.

Maximum particle size 180μm Average particle size 90μm Bulk density 0.45g / cc Effective pore volume 0.727 Wall thickness 1-3μm As mentioned above, even in this experiment, a mixture of fragile hollow spheres with small particle size and small wall thickness and fine powder Was obtained, and the hollow sphere was easily crushed by ultrasonic waves at the time of measuring the effective pore volume.

Claims (2)

(57) [Claims] A hollow sphere comprising a substantially anhydrous microporous solid outer shell containing sodium sulfate as a main component and 0.05 to 1.5% by weight of a surfactant, having an average outer diameter of 100 to 500 µm. A hollow sphere made of sodium sulfate having an effective pore volume of at least 0.5. 2. 40 to 70% by weight of sodium sulfate and a surfactant
A hollow sphere made of sodium sulfate, characterized in that an aqueous slurry containing 0.025 to 0.8% by weight is heated to at least 35 ° C and then sprayed into a high-temperature air stream at a temperature of 300 to 450 ° C to be dehydrated and dried. Manufacturing method.