JPS6351968B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing crystalline aluminosilicates. More specifically, the present invention relates to a method for producing a crystalline aluminosilicate slurry that is composed of fine particles and has a low content of coarse particles.

In particular, it is an object of the present invention to provide a method for producing synthetic zeolite having excellent performance as a detergent builder in high yield and productivity at low cost.

Conventionally, as a builder for detergents or cleaning agents,
Phosphate has been used as the main builder due to its low cost and high calcium ion exchange capacity. However, in recent years there has been a problem of eutrophication in lake water, etc., and builders based on phosphates are being replaced by builders based on aluminosilicate such as zeolite.

The general method for producing synthetic zeolites has been known for a long time. That is, it is produced by contacting and gelling a sodium silicate aqueous solution and a sodium aluminate aqueous solution in the presence of an excess alkali, and then heating for crystallization. For use in detergents and cleaning agents, the method is to gel and crystallize at a solid content concentration of 30% or less, and remove excess alkali by filtering and washing with water in a filter press, rotary filter press, etc. It is taken. At this time, the alkali in the liquid is concentrated, recovered, and reused. However,
Concentration for removing the excess alkali and recovering the alkali requires a large amount of expense and equipment investment, which increases the cost of zeolite. In addition, due to the rheological properties specific to zeolite, it is generally difficult to remove from an aluminosilicate suspension with a high solid content concentration of 30% or more, and gelation usually occurs at a solid content concentration of 30% or less.・The reality is that it is crystallized.

The present inventors conducted various studies on methods that could simplify the process and produce at a low cost without relying on such methods. It was found that the zeolite production range was also expanded, and therefore the amount of excess alkali was required to be less than when synthesis was performed at a low concentration. From this, it has become clear that it is possible to reduce the amount of alkali used in carrying out the reaction, neutralize it with an acid or acidic salt, and convert it directly into a builder component for detergents.

In addition, the aluminosilicate slurry synthesized at a high concentration is directly introduced into a detergent slurry consisting of other detergent active ingredients, auxiliary agents, etc., without the steps of filtration, water washing, and drying after the reaction, and is spray-dried to form a powder. It turns out that it is also possible to obtain synthetic detergents. Furthermore, when synthesized at a high concentration, less time is required for crystallization, and therefore the particle size of the zeolite particles produced tends to be smaller from a crystallographic point of view than when synthesized at a low concentration. I also found out.

To produce aluminosilicates at high concentrations,
The present inventors have found that there are various advantages as described above, but when manufacturing at a high concentration, it is difficult to control the growth rate of crystals due to the high concentration of the system, and it is difficult to control the growth rate of crystals. It has been found that so-called nodules or grain agglomerates, which are clusters of grains, may be formed. These nodules and granules are as shown in Figure 1a, but they are clusters of fine particles, and some have an average particle diameter of 10 to 20 microns.

It is extremely inconvenient for aluminosilicates used as builders for detergents and detergents to contain such coarse particles. That is, when an aluminosilicate of a certain particle size or more is used as a detergent builder, if water-insoluble particles adhere to clothes, there is a risk that the clothes will turn white after drying. Especially with water-saving washing machines, adhesion to clothes is very noticeable.
Therefore, zeolites containing such coarse particles cannot be used in practice, and zeolites with large particle sizes have a slow rate of ion exchange with calcium, making them unsuitable as detergent builders. 3 to 5μ, maximum 10μ is required.

The present inventors have conducted extensive studies to find a method for producing a high-concentration aluminosilicate suspension by pulverizing or not producing the above-mentioned granules or nodules. During crystallization, the mixture is circulated from the mixing tank to a crushing device with high shear force, and is crushed by applying high shear force, and finally the average particle size of the aluminosilicate is reduced. The present invention was completed based on the discovery that it is possible to suppress the particle size to 8μ or less. That is, the present invention provides a method for producing aluminosilicate by mixing a highly concentrated water-soluble silicate aqueous solution and a highly concentrated water-soluble aluminate aqueous solution, gelling them, crystallizing them, and simultaneously performing a crushing operation. This is what we provide.

On the other hand, the conventional method of pulverizing once crystallization is completed requires the operation of a powerful pulverizer such as a ball mill, sand mill, or attritor for a long time, and is still insufficient. This is extremely inefficient.

It is also possible to grind the gelled material to a certain particle size by grinding the gelled material before crystallization, but since the gelled material has the property of being relatively agglomerated, it is not possible to crystallize it even if it is ground once. This is not preferable since there is a possibility that agglomeration may occur in the step of step 2 and coarse particles may be formed.

Although the device used for pulverization in the present invention is not particularly limited, a pulverizer called a colloid mill, a disk integrator, or a homogenizer is usually used. Specifically, Hosokawa Iron Works
Disper Mill manufactured by Co., Ltd., Homo Mitsuku Line Mill manufactured by Tokushu Kika Kogyo Co., Ltd., Homo Mitsuku Mycolloider,
Homomitsuku line mixer etc. are mentioned.

The shearing force in the above-mentioned crushing device is desirably one that provides a shearing force of 5 m/sec or more at the circumferential speed of the outer circumference of the stirring blade or the rotating body.

Since the aluminosilicate slurry obtained by the method of the present invention has a solid content of 35% by weight or more, it can be used as it is in detergent formulations, and is of great value both economically and from a process standpoint.

According to the present invention, the reaction in such a concentrated system is
It is carried out using ~70% by weight aqueous aluminate solution and 30-50% by weight aqueous silicate solution. It is not preferable to use an aqueous solution with a higher concentration or a solid substance of the above-mentioned salt as a starting material.

In order for the produced slurry to be used as it is or after being neutralized for use in detergent formulations, it is desirable that the amount of excess alkali be small, but fortunately, as mentioned above, in the reaction in a concentrated system, Even with a small amount of excess alkali, an aluminosilicate with excellent builder performance can be obtained. In order to achieve the object of the present invention, the composition of the mixture of both the above aqueous solutions _should be _Na2O : _Al2O3 : _SiO2 : _H2O =1.2 to 2.5 in molar ratio.
It is necessary to adjust the ratio to be 1:1.5 to 3.0:15 to 35.

In the method of the present invention, gelation may be carried out batchwise or continuously. Further, the mixing method may be such that a water-soluble silicate aqueous solution is added to a water-soluble aluminate aqueous solution, or conversely, a water-soluble aluminate aqueous solution is added to a water-soluble silicate aqueous solution.

However, from the viewpoint of gel fluidity, it is most desirable to prepare an aluminosilicate gel in advance and add an aluminate aqueous solution and a silicate aqueous solution to it simultaneously.

In carrying out the present invention, it may be possible to circulate and crush the gel during gel preparation, but the effect is not so great, and when measuring the coarse particles in the gel using a 50μ wet sieve method, it is usually about 10% coarse. Particles are present.

Gelation is usually carried out at a temperature of 40 to 90°C.
It is necessary to perform this gelling adjustment so that crystallization does not occur. If crystallization begins during gelation adjustment, the crystallized core will accelerate the crystallization rate, and the added water-soluble aluminate and aqueous silicate will immediately crystallize, forming solid aggregates or nodules. Agglomerates are formed and cannot be easily pulverized even if pulverization is performed later.

Next, when gelation is completed, the temperature is raised to 60 to 110°C, and crystallization is carried out while circulating and pulverizing. Crystallization time is usually 15-120 minutes. The time required for crystallization mainly depends on the crystallization temperature, the gel concentration and the amount of excess alkali. If the crystallization time is too long or the temperature is too high, zeolite 4A will turn into hydroxysodalite, which has no ion exchange properties, so care must be taken.

Further, in carrying out the method of the present invention, it is desirable that the circulation rate to the mill is faster than the crystallization rate. The crystallization rate depends on the crystallization temperature, gel concentration,
Although it depends on the amount of excess alkali, the amount of seed gel, etc., the circulation speed is usually such that the gel or zeolite slurry in the mixing tank is circulated within the crystallization time, specifically within 1 hour, preferably 20 minutes. It is desirable to be able to cycle within minutes.

The mechanism of action of crushing at the time of crystallization in the present invention is as follows:
In the transition zone to crystallization, forming light aggregates,
This is to prevent the formation of strong aggregates by crushing and crushing. On the other hand, crushing after crystallization is not easy because strong aggregates are formed as described above.

After grinding and crystallization, the aluminosilicate slurry is cooled to below 80°C to prevent it from becoming sodalite. Due to the excess alkali content in the cooled aluminosilicate slurry, detergents or cleaning agents which, when used for detergents and detergents, should advantageously be prepared by neutralization with acids or acid salts. It can be converted into the components of

The acid or acidic salt used for the above neutralization may be an inorganic substance such as carbon dioxide gas or a mineral acid such as sulfuric acid or hydrochloric acid.

However, anionic surfactants in the form of organic acids, such as fatty acids, citric acid, polyacrylic acid, maleic acid, or acids such as alkylbenzene sulfonic acids, paratoluene sulfonic acids, alkyl sulfates, alkyl ether sulfates, etc., may also be used for this purpose. It can be used for. In addition, not only one type of acid or acidic salt, but also two or more types of acids or acidic salts can improve pH.
It is also possible to adjust.

The degree of neutralization is PH8.5 to 11.5, especially PH when the aluminosilicate suspension is measured as a 1% slurry.
A value of 10 to 11 is preferable because it exhibits excellent effectiveness as a detergent. Not leaving excess sodium hydroxide in the aluminosilicate suspension is important when spray drying a slurry of the aluminosilicate suspension and other detergent ingredients to produce a powdered detergent product. It is desirable to obtain good results in terms of powder physical properties, especially caking resistance, etc.

The suspension thus neutralized with an acid or an acidic salt is added directly to a slurry containing other detergent ingredients, and a powder detergent is obtained by spray drying.

In addition, when mixing and gelling a water-soluble silicate and a water-soluble aluminate, it is also possible to carry out the present invention by adding a dispersant such as an acrylic acid oligomer to the gelled product in order to improve its fluidity. It is.

Next, the structure and effects of the present invention will be explained in more detail by showing Examples and Comparative Examples, but the present invention is not limited to these Examples.

In the following Examples and Comparative Examples, coarse particles in aluminosilicate suspensions were examined using a test sieve with a fine diameter of 50 μm. The measurement method is to disperse the suspension well, weigh 2g of the suspension accurately, and soak it in 500ml of water at 25℃ for 5 minutes.
After stirring, the mixture is further washed with 500 ml of water, and the residue is obtained through the wire mesh described above. Then test this test sieve at 110
After drying in a dryer at ℃, it was accurately weighed and the sieve residue was calculated.

Particle size distribution is defined as the volume percentage of microcrystalline particles.
The results are shown using a light scattering particle size meter manufactured by Leeds & NORTHRUP.

Example 1 It has an external circulation system to a wet grinding device (Homo Mitsukline Mill LM-S type manufactured by Tokushu Kika Kogyo Co., Ltd.),
In a 200-meter mixing vessel with a two-stage propeller stirrer, 74 kg of an aqueous sodium aluminate solution with a molar ratio of Na ₂ O / Al ₂ O ₃ /H ₂ O = 1.06/1/8 and 3
Sodium silicate aqueous solution (Na ₂ O/
SiO ₂ /H ₂ O = 1/3.15/22.3 molar ratio) was added at a rate of 300Kg/Hr and 400Kg/Hr, respectively.
Mixed.

The mixing tank has a jacket for heating, and the temperature inside the mixing tank is controlled by steam of 2 kg/cm ² G.
The temperature was raised to 70°C, and the mixture was sent through an opening valve at the bottom of the mixing vessel to a homomic line mill, a wet grinding device with discharge performance, for circulation. The rotation speed of the Homo Mitsukline mill is 3600 rpm, and the shear speed is calculated from the peripheral speed of the internal turbine blades to be 15 m/min.
It was hot in sec. The temperature was gradually increased and the line mill was operated and circulated until it reached 90°C. After 30 minutes, crystallization was complete and circulation was stopped. The gap between the turbine blades and stator inside the Homo Mitsukline mill is
It was 0.5mm. The circulation rate to the Homomitsuku line mill is 30/min, and the number of circulations is calculated as follows.
It was about 8 times.

The amount of coarse particles in the aluminosilicate suspension after crystallization was measured using the 50μ wet sieve method described above and was found to be 0.1%. Furthermore, observation using a microscope confirmed that there were no nodules or granules. Particle size distribution was measured using a light scattering particle size meter manufactured by Leeds & NORTHRUP. The volume average diameter is
It was 4.9μ. The measurement results show the following particle spectra. (Table 1).

Table 1 Fraction (μm) <31 100% <22 99% <16 97% <11 96% <7.8 83% <5.5 79% <3.9 55% <2.8 29% Crystallized aluminosilicate suspension Liquid temperature is 70℃
Cool to 1% and make 1% slurry with carbon dioxide gas.
Neutralized until 10.6.

After neutralizing excess alkali, the aluminosilicate suspension was directly added to a detergent slurry containing other detergent actives, builders, adjuvants, etc. and spray-dried.
The detergency and powder physical properties of the obtained powder detergent were the same as those of a powder detergent produced using a commercially available aluminosilicate. In addition, an adhesion test to clothing was conducted using a water-saving washing machine, and the adhesion of water-insoluble substances to clothing did not pose a practical problem.

Comparative Example 1 Gelation and crystallization were performed in the same manner as in Example 1 without circulation to a wet grinder.

After the crystallization was completed, the mixture was sent to a wet grinding device with discharge performance through an opening valve at the bottom of the mixing vessel, and circulated under the same conditions as in Example 1. 30 cycles
After a few minutes, the amount of coarse particles in the aluminosilicate suspension was measured by the wet sieving method described above, and it was still 6%. 3 more
Although time cycling and pulverization were repeated, there was still 3% sieve residue when measured using a wet sieve method. After 3 hours of circulation, the particle size distribution was measured using a light scattering granulometer. The measurement results are shown in Table 2.

Table 2 Fractions <88 100% <62 99 <44 96 <31 86 <22 75 <16 65 <11 51 <7.8 39 <5.5 28 <3.9 16 <2.8 8 Comparative Example 2 In the same manner as Example 1 After gelling and mixing at 50°C, the mixed/gelling liquid was kept at 40 to 50°C and sent to a wet grinding device with discharge performance through the opening valve at the bottom of the mixing container, under the same conditions as in Example 1. The coarse particles in the gelled solution after 30 minutes of circulation were measured using the wet sieving method described above and found to be 4%. The mixture was circulated for an additional 3 hours, after which the circulation was stopped and the temperature was raised to 100°C to allow crystallization. The time required for crystallization was 20 minutes. When measuring coarse particles in the aluminosilicate suspension after crystallization using the wet sieving method described above,
There was 1.5% sieve residue. After 3 hours of circulation, the particle size distribution was measured using a light scattering granulometer. The measurement results are shown in Table 3.

Table 3 Fraction <88 100% <62 98 <44 96 <31 90 <22 80 <16 70 <11 58 <7.8 42 <5.5 31 <3.9 18 <2.8 8 Comparative Example 3 Mixing and After gelation and crystallization, a portion of the aluminosilicate suspension was extracted and subjected to repeated treatment with Mycoloider (LS type manufactured by Tokushu Kika Kogyo).
Passed it 10 times. The gap between the Mycolloider grinding wheels was 0.5 mm, and the rotation speed of the grinding wheels was 3600 rpm. The coarse particles in the aluminosilicate suspension passed 10 times were still 8% when measured using the wet sieving method described above.
There was some sieve residue.

[Brief explanation of drawings]

Figure 1a is a microscopic sketch of nodules that appear during the synthesis of aluminosilicate suspensions at high concentrations, and Figure 1b is a zeolite that does not form nodules.
It is a similar figure to a of the 4A particle.

Claims (1)

[Scope of Claims] 1. When producing a crystalline aluminosilicate by mixing and gelling an aluminate aqueous solution and a silicate aqueous solution, followed by hydrothermal crystallization, the aluminate aqueous solution has a concentration of 30 to 70% by weight. Using an aqueous solution and an aqueous solution having a concentration of 30 to 50% by weight as an aqueous silicate solution, the composition of the mixture of both aqueous solutions is in a molar ratio;
_Na2O : _Al2O3 : _SiO2 : _H2O =1.2 _~ 2.5:1:1.5
3.0: A method for producing a crystalline aluminosilicate, which comprises mixing at a ratio of 15 to 35 and simultaneously crystallizing and pulverizing to produce a crystalline aluminosilicate slurry having a slurry concentration of 35% by weight or more. 2. The method for producing crystalline aluminosilicate according to claim 1, wherein the pulverization is carried out using a pulverizer installed in a circulation system.