JP2009137797A - Synthetic amorphous aluminum-coupled silicate, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic amorphous aluminum-coupled silicate having low grindability and high cleanability, and further having transparency when used as a silica base for transparent toothpaste, wherein the storage stability of the transparency is excellent, and to provide a method for producing the same. <P>SOLUTION: Disclosed is a synthetic amorphous aluminum-coupled silicate in which the content of aluminum obtained by reacting a water soluble alkali metal silicate, a water soluble aluminum salt and mineral acid as essential raw materials in the presence of the mineral acid salt electrolyte of water soluble alkali metal lies in the range of 0.5 to 7.5 mass% to SiO<SB>2</SB>expressed in terms of Al<SB>2</SB>O<SB>3</SB>, 5 mass% slurry pH is 8.0 to 10.0, pore sizes are 1.85 to 2.10 nm, and also, the content of an OH group is 2.0 to 3.5 mass% with respect to SiO<SB>2</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a synthetic amorphous aluminum-bonded silicate having low polishing properties and high cleaning properties that do not damage teeth, and high transparency and transparency as a silica base for transparent dentifrice, and its production Regarding the method.

  Conventionally, fine powder silicic acid or calcium carbonate, calcium phosphate, and aluminum hydroxide produced by wet or dry methods have been used as dentifrice bases, and many new manufacturing methods have been developed and quality improvements or usage improvements have been made so far. Has been done.

  Currently, the fine powdered silicic acid used as a dentifrice silica base is a fine powdered silicic acid produced mainly by a wet method, generally referred to as a precipitated fine powdered silicic acid, which is produced by a dry method. Differentiated from powdered silicic acid. Such precipitated fine powdered silicic acid is usually produced by reacting a water-soluble alkali metal silicate with a mineral acid such as sulfuric acid, hydrochloric acid, nitric acid in the range of 60-100 ° C., and filtering and drying the precipitated silicic acid. Is done. However, when these are used as a dentifrice silica base, since they generally have a Mohs hardness of 4.5 to 5.0, there is a drawback that the abrasiveness is high and the teeth are damaged. Therefore, a method for producing a synthetic silicate having a low polishing property and a high cleaning property that does not damage the teeth is desired and has been developed.

As a means of obtaining a synthetic silicic acid having low abrasiveness and high cleanability that does not damage the teeth, the present applicants used water-soluble alkali metal silicate and inorganic water-soluble zirconium salt, or water-soluble titanium salt and mineral acid. It was proposed that the synthetic amorphous silicate obtained by reacting as a raw material is optimal as a dentifrice silica base. (See Patent Documents 1 and 2) In addition, a method of producing precipitated silica having a high level of abrasiveness by reacting sodium silicate with a mineral acid in the presence of an electrolyte is also known. (See Patent Document 3)
On the other hand, in the technology of blending a dentifrice silica base into a transparent toothpaste, a method of controlling the refractive index of the dentifrice silica base is important as a feature, and it is known that the refractive index can be controlled by adding aluminum. Yes. The dentifrice silica base that has the maximum transparency within the refractive index range of 1.44 to 1.46 is required as the physical properties of the dentifrice silica base necessary for transparent toothpaste. (See Patent Documents 4 and 5)
However, although the techniques of Patent Document 1 and Patent Document 2 can provide a dentifrice silica base material having suitable polishing properties and cleaning properties that do not damage the teeth, it can be used for transparent toothpaste under a refractive index range of 1.44 to 1.46. There was a problem that excellent transparency with a transmittance of 70% or more could not be obtained. In addition, the aluminum-added silicate obtained by the techniques of Patent Document 4 and Patent Document 5 provides transparency with a transmittance of 70% or more under the refractive index region of 1.44 to 1.46, but the storage stability of transparency. In addition, it is difficult to control the abrasiveness, and high polishing and high cleaning or low polishing and low cleaning.In other words, it has strong dirt removal power but also damages teeth, or teeth are not damaged, but dirt Only those with weak removal power could be obtained. Accordingly, there has been a demand for a dentifrice silica base having low polishing properties and high cleaning properties that do not damage teeth, and high transparency.

Japanese Patent Laid-Open No. 14-293530 Japanese Patent Laid-Open No. 11-140428 Japanese Patent Publication No.5-22644 Japanese Patent Publication No.59-20601 Japanese Patent Publication No.62-50403

  The present invention relates to a synthetic amorphous silicate having low polishing properties and high cleaning properties that do not damage teeth, and high transparency and transparency as a silica base for transparent dentifrice, and a method for producing the same. The purpose is to provide.

  Therefore, the present inventors have synthesized amorphous form obtained by reacting water-soluble alkali metal silicate, water-soluble aluminum salt and mineral acid as essential raw materials in the presence of a water-soluble alkali metal mineral salt electrolyte. It was discovered that silicate has low abrasiveness and high cleaning properties that do not damage teeth, and has high transparency and excellent storage stability as a transparent dentifrice base. It has been completed.

That is, the present invention is, in the presence of a water-soluble alkali metal mineral acid salt electrolyte, obtained by reacting a water soluble alkali metal silicate and a water soluble aluminum salt and a mineral acid as an essential raw material, aluminum Al ₂ O ₃ as a range of 0.5 to 7.5% by mass with respect to SiO ₂ , 5% by mass slurry pH is 8.0 to 10.0, pore diameter is 1.85 to 2.10 nm, and OH group amount is 2.0 to 3.5% by mass with respect to SiO ₂ The present invention relates to a synthetic amorphous aluminum-bonded silicate.

  Furthermore, the present invention adds a water-soluble aluminum salt and a mineral acid to an aqueous solution of a water-soluble alkali metal silicate in the presence of a water-soluble alkali metal mineral salt electrolyte to cause a reaction, and a 5 mass% slurry pH is 8.0. It is related with the manufacturing method of the said synthetic amorphous aluminum bond silicate characterized by adjusting so that it may become -10.0. The synthetic amorphous aluminum-bonded silicic acid of the present invention thus obtained is characterized by having a transparency of 70% or more in the range of refractive index of 1.44 to 1.46 and excellent transparency storage stability. To do.

  According to the present invention, when used as a dentifrice silica base, the refractive index is in the range of 1.44 to 1.46, the transparency is 70% or more, the storage stability of the transparency is excellent, and the abrasiveness is low polishing that does not damage the teeth. In addition, it is possible to obtain a synthetic amorphous aluminum-bonded silicate that is highly clean.

  The synthetic amorphous aluminum-bonded silicate of the present invention will be described in detail below based on its production method.

First, examples of the water-soluble alkali metal silicate used in the present invention include sodium, potassium and lithium silicates, but sodium silicate is generally used because of its relatively low cost. A water-soluble alkali metal silicate having a molar ratio of SiO ₂ / M ₂ O (where M represents an alkali metal) in the range of 2 to 4 can be used.

  In the present invention, a mineral acid such as hydrochloric acid, sulfuric acid or nitric acid can be used as the acidifying agent for the water-soluble alkali metal silicate.

Regarding the SiO ₂ concentration of the water-soluble alkali metal silicate solution, it can be used within a range of 5 to 15% by mass. Below the lower limit, it is not preferable from the viewpoint of production efficiency, and when it exceeds the upper limit, a synthetic amorphous aluminum-bonded silicate having the physical properties of the present invention cannot be obtained. Next, regarding a mineral acid density | concentration, 5-25 mass% can be used, More preferably, 10-20 mass% is good. By appropriately selecting other conditions for these raw material concentrations, the intended synthetic amorphous aluminum-bonded silicate of the present invention can be obtained within this range.

  The important point in the present invention is that the water-soluble alkali metal mineral salt electrolyte is present in the reaction system in the proportion described later. An important point is to add a water-soluble aluminum salt in a step of obtaining a fine powder silicate by reacting a water-soluble alkali metal silicate solution with a mineral acid. Furthermore, it is important to start these reactions from the alkali side. And more important point is to adjust the 5 mass% slurry pH obtained in the final product to be 8.0 to 10.0, and by following these important points, the object of the present invention can be achieved. it can.

  In general, by adding an electrolyte described later in the step of obtaining a fine powder silicate by reacting a water-soluble alkali metal silicate solution with a mineral acid, the cleaning property for the teeth is improved, but at the same time, the polishing property is improved. Tend to be larger. In order to obtain the desired polishability and cleanability in the present invention, it is beneficial to interpose aluminum in the step of depositing the precipitated fine powder silicate. That is, as will be described later, when the amount of aluminum is increased, the cleanability is lowered without deteriorating the cleanability. In the present invention, the desired low-polishing and high-cleaning dentifrice silica base can be obtained by appropriately selecting the amount of the electrolyte and the amount of the water-soluble aluminum salt that is the aluminum raw material.

The electrolyte used in the present invention is a water-soluble alkali metal mineral acid salt, specifically sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, or potassium nitrate. With regard to the amount used, M 2 _{O (where,} M is. For an alkali metal) is 5 to 30 mass% with respect to SiO ₂ of the water-soluble alkali metal silicate as. If the amount used is less than the lower limit, the effect is not sufficient, and if the amount exceeds the upper limit, the abrasive becomes highly abrasive and the silicate targeted by the present invention cannot be obtained. As the method of use, it is preferable that the electrolyte is contained in the water-soluble alkali metal silicate solution in advance, but the electrolyte may be added to the mineral acid and reacted.

  As the aluminum donating substance, a water-soluble aluminum salt described later can be used, and as a method of use thereof, the water-soluble aluminum salt solution may be diluted to a predetermined concentration and directly reacted, but the present inventors recommend As an example of the method, a water-soluble aluminum salt is added to a mineral acid in advance to obtain an aluminum-containing mineral acid, and this is reacted with a water-soluble alkali metal silicate solution. By carrying out this method, it is possible to produce aluminum in a state in which aluminum is dispersed more uniformly in silica than in other methods.

Examples of the water-soluble aluminum salt used in the present invention include, but are not limited to, aluminum chloride, aluminum sulfate, and aluminum nitrate. Regarding the amount of the water-soluble aluminum salt, as Al ₂ O _3, ranges from 0.5 to 7.5 wt% with respect to SiO ₂ of the water-soluble alkali metal silicate. Furthermore, the range of 1.0-6.0 mass% is more preferable. If the lower limit is not reached, the effect of addition is not sufficient to reduce the high abrasiveness associated with the addition of the electrolyte, and if the upper limit is exceeded, the abrasiveness required as a dentifrice base is lowered, which is not desirable. When a mineral acid containing aluminum is used, it may be appropriately adjusted within the above range and used for the reaction.

  By the way, it is important that the reaction of the water-soluble alkali metal silicate, the water-soluble aluminum salt and the mineral acid starts from the alkali side as described above. When the reaction is started from the acidic side, a gel-like substance is formed, and the target product cannot be obtained.

  Note that starting the reaction in the present invention from the alkali side means that nucleation is carried out on the alkali side. Specifically, for example, (1) a water-soluble alkali metal silicate is previously charged in the reaction vessel. In this method, a water-soluble aluminum salt and a mineral acid are added and reacted, and (2) a water-soluble aluminum salt-containing mineral acid and a water-soluble alkali metal silicate are simultaneously added to a reaction vessel. (3) A water-soluble alkali metal silicate is charged in advance in a reaction vessel, and the mineral acid and the water-soluble aluminum salt are added. It is a method of adding the desired amount simultaneously or separately, and the point is that the nucleation of silica is carried out on the alkali side.

  Regarding the reaction temperature, it is important that the temperature is 60 to 100 ° C. That is, when other reaction conditions are the same, when the reaction temperature is lower than 60 ° C., the cohesive force of the secondary particles is weak, and a low-polishing and high-cleaning dentifrice silica base by adding aluminum cannot be obtained.

  In terms of pH, it is important that the reaction end pH is 6-9. That is, when the other reaction conditions are the same, if the reaction completion pH exceeds 9, the precipitation of the synthetic amorphous silicate is not performed completely, and the reaction yield deteriorates. It becomes difficult to produce the synthetic amorphous aluminum-bonded silicate that is the object of the invention. That is, when the reaction completion pH is less than 6, it becomes difficult to obtain a dentifrice silica base excellent in transparency storage stability. In the present invention, what is important is to produce the product so that the 5 mass% slurry pH of the product is 8.0 to 10.0. By producing the slurry so that the 5 mass% slurry pH is 8.0 to 10.0, a base excellent in transparency storage stability can be obtained. The best method for producing a 5 mass% slurry pH of 8.0 to 10.0 is that in a repulping process in which a wet cake obtained by filtration is dispersed in several times the amount of water and washed, the pH is It is a method of adjusting. In the adjustment, when the pH is higher than the desired pH, the mineral acid used in the present invention can be used. When the pH is too low, a water-soluble alkali metal salt may be added separately. Examples of the water-soluble alkali metal salt used for this purpose include sodium hydroxide, carbonate and bicarbonate. Thus, by adjusting the 5 mass% slurry pH obtained in the final product to be 8.0 to 10.0, the transparency is 70% or more in the range of refractive index of 1.44 to 1.46 as a transparent dentifrice silica base. In addition, the synthetic amorphous aluminum-bonded silicate of the present invention having excellent transparency and storage stability can be obtained.

  The synthetic amorphous aluminum-bonded silicate of the present invention thus produced has low abrasiveness and high cleanability, is extremely suitable as a silica base for dentifrice, and is transparent when made into a transparent dentifrice. It is suitable as a dentifrice silica base having a high property of 70% or more and excellent storage stability of transparency.

  In general, the RDA method and the Tobacco Jani method have been proposed and used as methods for evaluating the polishing properties and cleaning properties of dentifrice abrasives, respectively, but the evaluation methods are complicated and costly. Therefore, in the present invention, evaluation was performed by the measurement method described later. Regarding the polishing property, a metal plate is used as the polishing plate, and the polishing amount in the range of 0.3 to 1.0 mg is preferable from the correlation with the RDA value used for evaluation of polishing properties of teeth and the like. If it is below the lower limit, it cannot be expected to function as an abrasive, and if it exceeds the upper limit, the abrasiveness is too strong, which is not preferable. Moreover, regarding the cleaning property, the range of 40 to 80 brushing times in the test method is preferable from the correlation with the tobacco stain method used for evaluating the cleaning property of teeth and the like. If the lower limit is not reached, the cleaning property is so high that the teeth and the like are damaged.

As a matter of note in the production of the synthetic amorphous aluminum-bonded silicate of the present invention, as described above, in addition to starting the reaction on the alkali side, silica in a water-soluble alkali metal silicate solution ( The water-soluble aluminum salt is added and reacted in the process until the SiO ₂ ) component is completely precipitated, and the water-soluble aluminum salt is preferably previously contained in the mineral acid. That is, the synthetic amorphous aluminum-bonded silicate of the present invention cannot be obtained even when a water-soluble aluminum salt is added from the time when all the silica has been precipitated. For example, in a method in which a water-soluble alkali metal silicate solution and a mineral acid are added simultaneously, the water-soluble aluminum salt should be added by the end of the addition of both. After the addition of the water-soluble aluminum salt, the mineral acid may be added to a desired pH depending on the application. The synthetic amorphous aluminum-bonded silicate obtained as described above has a feature that the aluminum elution rate described later is 100 ppm or less. That is, it is considered that a silicate in which aluminum is firmly bonded is formed. As described above, it is necessary to add and react the water-soluble aluminum salt in the process until the silica (SiO ₂ ) content in the water-soluble alkali metal silicate solution is completely precipitated. When a water-soluble aluminum salt is added from the time point, the bond with silica is insufficient, and the aluminum elution rate exceeds 100 ppm, and the silicate of the present invention cannot be obtained.

  After completion of the reaction / repulp washing, the slurry is filtered and washed by a usual method, and the obtained synthetic amorphous aluminum-bound silicate is separated from the liquid, dried and pulverized to obtain a product.

The synthetic amorphous aluminum-bound silicate produced in this way is amorphous by powder X-ray diffraction (see FIG. 1), has a pore diameter of 1.85 to 2.10 nm (see FIG. 2), and OH It is characterized in that the base amount is 2.0 to 3.5% by mass with respect to SiO ₂ .

  The synthetic amorphous aluminum-bonded silicate of the present invention is obtained by adding a water-soluble aluminum salt and a mineral acid to an aqueous solution of a water-soluble alkali metal silicate in the presence of an alkali metal mineral salt electrolyte as described above. It can be manufactured by reacting and adjusting the 5 mass% slurry pH to be 8.0 to 10.0. Although it is not clear about the relationship between the physical properties of the present invention synthetic amorphous aluminum-bonded silicate and polishing properties, cleanability, transparency at a specific refractive index, storage stability of transparency, etc. For the first time, moderate abrasiveness and cleanability, and excellent transparency and storage stability are exhibited.

  The synthetic amorphous aluminum-bonded silicate of the present invention having the above physical properties has moderate polishing properties of low polishing and high cleaning as a dentifrice base, and further exhibits high transparency when used as a transparent toothpaste, It is an excellent base for transparent dentifrice because of its excellent storage stability.

  Next, in describing the present invention in more detail, terms used in the present invention, that is, 5% by mass slurry pH, pore diameter, powder X-ray diffraction, refractive index and transparency, storage stability test, abrasiveness, cleanability, The OH group amount and aluminum elution amount will be described.

1. 5% by weight slurry pH
5 g of a sample was put in 95 ml of deionized water and stirred to prepare a suspension, and the reading after stirring for 2 minutes was set to 5 mass% slurry pH by the pH measurement method of the cosmetic raw material standard general test method.

2. Pore diameter BELSORP MINI manufactured by Nippon Bell Co., Ltd. is used, liquid nitrogen is used as a coolant, nitrogen gas is adsorbed at -196 ° C, and the pore size is determined by the Dollimore-Heal method from the desorption amount of the nitrogen gas. The distribution was calculated, and the maximum frequency diameter was defined as the pore diameter. The sample was degassed at 120 ° C for 60 minutes.

3. Powder X-ray diffraction X-ray diffraction was performed under the conditions of 30 kV and 40 mA using a Cu tube using an XRD-7000 manufactured by Shimadzu Corporation.

4. Refractive index and transparency
A suitable amount of D-sorbitol and water are mixed to prepare dispersion media having various refractive indexes, and 2 g of the sample is dispersed in 18 g of each dispersion medium, followed by vacuum degassing. The refractive index and transparency of this mixture at 25 ° C are measured, a refractive index-transparency curve is drawn, the refractive index of the mixture when the transparency is maximum is taken as the refractive index of the sample, and the transparency at that time is taken as the transparency of the sample. To do. An Atpe Co., Ltd. appe refractometer was used for refractive index measurement, and U-2000 made by Hitachi, Ltd. was used for transparency measurement. Transparency measurement was performed using a wavelength of 590 nm and a transparent cell made of KARTELL and having a thickness of 10 mm.

5. Storage stability test The sample having the refractive index and transparency measured by the method is stored in a constant temperature bath at 50 ° C., and the transparency after one month is measured.

6. Using a polishing horizontal reciprocating brushing type polishing machine, place a 60% aqueous glycerin solution containing 15% of the sample on a smooth metal plate, polish it 20,000 times with a load of 400 g, and then measure the weight loss of the metal plate. This was made abrasive.

7. Using a cleaning oil-based magic pen (Zebra Co., McKee), three wires of 20 x 4 mm were placed on a glass plate (Matsunami Glass Industry Co., Ltd., Micro Slide Glass, 76 x 52 x 1.1). mm), 1 g of 60% glycerin aqueous solution containing 15% of the sample was placed on the glass plate, polished using a horizontal reciprocating brushing type polishing machine with a load of 400 g, and three drawn with the magic pen. The number of brushing times when the line disappeared was measured, and this was defined as a cleaning property.

8. OH group amount Using EXSTAR-6000 manufactured by Seiko Denshi Kogyo Co., Ltd., and calculating the OH / SiO ₂ (mass%) using the following formula based on the weight change between 190 ° C and 900 ° C. It was set as the basis weight. The amount of OH groups is the same as the amount of water released between 190 ° C and 900 ° C.
OH / SiO ₂ (mass%) = (mass after firing at 190 ° C.−mass after firing at 900 ° C.) / Mass after firing at 190 ° C.
9. Aluminum elution amount
1 g of the sample was placed in a 100 ml Erlenmeyer flask, 80 g of 1M sulfuric acid was added, and the mixture was heated and stirred at 95 ° C. for 3 hours. After cooling, the filtrate, which was filtered using a membrane filter (ADVANTEC Celluose Nitrate 0.3 μm), was taken up in a 100 ml volumetric flask to prepare a test solution. Next, the amount of aluminum in this test solution was measured using ICP-AES manufactured by Jarrell-Ash, and the amount of aluminum eluted per gram of the sample was determined.

  Now, the synthetic amorphous aluminum-bonded silicate of the present invention has the above-described physical properties, has an appropriate polishing property and cleanability as a transparent dentifrice base, and has high transparency and its storage stability. However, it is extremely useful when used for various types of polishing such as plastic abrasives, metal abrasives, glass abrasives as well as dentifrice bases.

Hereinafter, examples of the present invention will be further described, but unless otherwise specified, all percentages indicate mass%.

[Example 1] In a reaction vessel with a 20 L baffle plate equipped with a stirrer having 150 mmφ turbine blades, 10 kg of 10% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution was placed, and sodium chloride was added to this solution with Na ₂ O. Mix as 6.4% as / SiO ₂ and keep the reaction temperature at 95 ° C. Further, add the 8% Al ₂ O ₃ aluminum sulfate solution and 10% sulfuric acid mixed solution at a rate of 80 ml / min, and then add 10% sulfuric acid until the pH is 7.0, as shown in Table 1. did. Next, the produced slurry was filtered, and the obtained wet cake was repulped. During this repulping, 10% sulfuric acid was added to adjust the slurry pH to 8.0. Thereafter, filtration and drying were performed to produce synthetic amorphous aluminum-bonded silicates having different aluminum contents. The 5 mass% slurry pH of the product was in the range of 9.1 to 9.5, and the aluminum elution amount was in the range of 20 to 35 ppm.

[Comparative Example 1]
A synthetic amorphous silicate was obtained under the same conditions as in Example 1 except that the aluminum sulfate solution was not added.

[Comparative Example 2]
The reaction vessel used in Example 1 is charged with 10 kg of a 10% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution and maintained at a reaction temperature of 95 ° C. Further, a mixed solution of 190 ml of 8% Al ₂ O ₃ aluminum sulfate solution and 2850 ml of 10% sulfuric acid was added at a rate of 80 ml / min, and then 10% sulfuric acid was added at pH 7.0 so that the ratio was as shown in Table 1. Added until. Next, the produced slurry was filtered, and the obtained wet cake was repulped. During this repulping, 10% sulfuric acid was added to adjust the slurry pH to 8.0. Thereafter, filtration, drying and pulverization were performed to obtain a synthetic amorphous silicate.

[Comparative Example 3]
The reaction vessel used in Example 1 is charged with 5 kg of a 10% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution and maintained at a reaction temperature of 95 ° C. Furthermore, add the mixed solution of 190% 8% Al ₂ O ₃ aluminum sulfate solution and 2850 ml of 10% sulfuric acid at a rate of 80 ml / min until the silica precipitates so that the ratio is as shown in Table 1. did. Then, the remaining solution of the above mixed solution of 10% sulfuric acid and 8% Al ₂ O ₃ aluminum sulfate solution and 5 kg of 10% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution are 80 ml / min and 120 ml / min, respectively. Added at a rate of min, then 10% sulfuric acid was added until pH 7.0. Next, the produced slurry was filtered, and the obtained wet cake was repulped. During this repulping, 10% sulfuric acid was added to adjust the slurry pH to 8.0. Thereafter, filtration, drying, and pulverization were performed to obtain a synthetic amorphous silicate.

[Comparative Example 4]
In the reaction vessel used in Example 1, 10 kg of 10% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution was added, and 6.4% sodium chloride was mixed as Na ₂ O / SiO ₂ and the reaction temperature was 95 ° C. Hold on. Further, a mixed solution of titanium oxychloride solution and 3400 ml of 10% sulfuric acid was added at a rate of 80 ml / min, and then 10% sulfuric acid was added until the pH reached 7.0 so that the ratio shown in Table 1 was obtained. Next, the produced slurry was filtered, and the obtained wet cake was repulped. During this repulping, 10% sulfuric acid was added to adjust the slurry pH to 8.0. Thereafter, filtration, drying, and pulverization were performed to obtain a synthetic amorphous silicate.

  The results of Example 1 and Comparative Examples 1 to 4 are shown in Tables 1 and 2.

As is apparent from Tables 1 and 2, the synthetic amorphous aluminum-bonded silicate of the present invention has low abrasiveness and high cleaning properties. Moreover, it turns out that the synthetic amorphous aluminum bond silicate of this invention has transparency of 70% or more in the range of refractive index 1.44-1.46, and is useful as a base for transparent dentifrice.

[Example 2]
Into the reaction vessel used in Example 1, 10 kg of 10% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution was added, and 15% of sodium sulfate was mixed as Na ₂ O / SiO ₂ to a reaction temperature of 95 ° C. Hold. To this, a mixed solution of 190 ml of 8% Al ₂ O ₃ aluminum sulfate and 2850 ml of 10% sulfuric acid was added at 80 ml / min (Al ₂ O ₃ / SiO ₂ = 2% by mass), and then 10% sulfuric acid was reacted. The solution was added until the reaction end pH reached 7.0. Next, the produced slurry was filtered, and the obtained wet cake was repulped. During this repulping, 10% sulfuric acid was added to adjust the slurry pH to 8.0. Thereafter, filtration, drying, and pulverization were performed to obtain the synthetic amorphous aluminum-bonded silicate of the present invention. The resulting synthetic amorphous aluminum-bonded silicate had an abrasive property of 0.7 mg, a cleaning property of 51 times, a transparency of 83.8% T at a refractive index of 1.444, an OH group content of 2.20% by mass, and a pore diameter of 2.00 nm. Further, when a storage stability test was conducted, the transparency was 82.3% T, and the storage stability of the transparency was very good.

[Example 3]
Into the reaction vessel used in Example 1, 10 kg of 10% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution was added, 10% sodium chloride was mixed as Na ₂ O / SiO ₂ and the reaction temperature reached 90 ° C. Hold. A mixed solution of 8 ml Al ₂ O ₃ aluminum chloride 200 ml and 10% sulfuric acid 2850 ml is added at a rate of 80 ml / min so that the addition ratio of Al ₂ O ₃ to SiO ₂ is 2.0%, and then 10% sulfuric acid Was added until pH 7.0. Next, the produced slurry was filtered, and the obtained wet cake was repulped. During this repulping, 10% sulfuric acid was added to adjust the slurry pH to 8.5. Thereafter, filtration and drying were performed to produce a synthetic amorphous aluminum-bonded silicate. The obtained synthetic amorphous aluminum-bonded silicate had a polishing property of 0.7 mg, a cleaning property of 49 times, a transparency of 82.4% T at a refractive index of 1.450, an OH group content of 2.08% by mass and a pore diameter of 2.00 nm. The aluminum elution amount was 28 ppm, and the transparency of the storage stability test was 81.1% T. The 5% slurry pH of the product was 9.6.

[Comparative Example 5]
Into the reaction vessel used in Example 1, 10 kg of 10% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution was added, 10% sodium chloride was mixed as Na ₂ O / SiO ₂ and the reaction temperature reached 90 ° C. Hold. To this was added 2850 ml of 10% sulfuric acid at a rate of 80 ml / min, and then 10% sulfuric acid was added until pH 8.5. Thereafter, 200 ml of 8% Al ₂ O ₃ aluminum chloride solution was added so that the addition ratio of Al ₂ O ₃ to SiO ₂ was 2.0%. At that time, the reaction end pH was 7.0. Next, the produced slurry was filtered, and the obtained wet cake was repulped. During this repulping, 10% sulfuric acid was added to adjust the slurry pH to 8.0. Thereafter, filtration and drying were performed to produce an aluminum-containing synthetic amorphous silicate. As a result of measuring the aluminum elution amount, it was 200 ppm.

[Comparative Example 6]
In Example 3, a synthetic amorphous aluminum-bound silicate was produced in the same manner as in Example 3 except that the amount of sodium chloride was 1% as Na ₂ O / SiO ₂ . The obtained synthetic amorphous aluminum-bonded silicate had an abrasive property of 0.2 mg, a cleaning property of 130 times, a transparency of 78.6% T at a refractive index of 1.448, an OH group content of 1.86% by mass and a pore diameter of 1.93 nm.

[Comparative Example 7]
In Example 3, an attempt was made to produce a synthetic amorphous aluminum-bonded silicate in the same manner as in Example 3 except that the amount of sodium chloride was 40% as Na ₂ O / SiO ₂ . The sodium silicate solution gelled and the synthetic amorphous aluminum bonded silicate of the present invention could not be produced.

[Comparative Example 8]
In Example 1, instead of sodium chloride, an attempt was made to produce a synthetic amorphous aluminum-bonded silicate in the same manner using the same amounts of magnesium sulfate, magnesium chloride and calcium chloride as the electrolyte. The sodium acid solution gelled and the synthetic amorphous aluminum bonded silicate of the present invention could not be produced.

[Comparative Example 9]
A synthetic amorphous aluminum-bonded silicate was produced in the same manner as in Example 2 except that 10% sulfuric acid was added during repulping in Example 2 to adjust the slurry pH to 5.5. The transparency of the obtained synthetic amorphous aluminum-bonded silicate at a refractive index of 1.450 was 82.4% T, and the transparency of the storage stability test was 61.3% T, and the transparency was remarkably reduced by storage.

1 is a powder X-ray diffraction pattern of an unfired synthetic amorphous aluminum-bonded silicate of the present invention produced in Example 1. FIG. 1 is a pore size distribution diagram of a synthetic amorphous aluminum-bonded silicate (Al ₂ O ₃ / SiO ₂ 2%) produced in Example 1. FIG. 2 is a pore size distribution diagram of the synthetic amorphous silicate produced in Comparative Example 1. FIG. 5 is a pore size distribution diagram of the synthetic amorphous silicate produced in Comparative Example 2. FIG. 6 is a pore size distribution diagram of the synthetic amorphous silicate produced in Comparative Example 3. FIG.

Claims (7)

Aluminum obtained by reacting water-soluble alkali metal silicate, water-soluble aluminum salt and mineral acid as essential raw materials in the presence of a water-soluble alkali metal mineral salt electrolyte is converted into SiO ₂ as Al ₂ O ₃ On the other hand, in the range of 0.5 to 7.5% by mass, the synthesis is characterized in that the 5% by mass slurry pH is 8.0 to 10.0, the pore diameter is 1.85 to 2.10 nm, and the OH group amount is 2.0 to 3.5% by mass with respect to SiO _2. Amorphous aluminum bonded silicate. The amount of the water-soluble alkali metal mineral salt electrolyte is 5 to 30% by mass with respect to SiO ₂ of the water-soluble alkali metal silicate as M ₂ O (wherein M represents an alkali metal). Synthetic amorphous aluminum bonded silicate as described. The synthetic amorphous aluminum-bound silicate according to claim 1 or 2, wherein the water-soluble aluminum salt is aluminum chloride, aluminum sulfate or aluminum nitrate. 4. The synthetic amorphous aluminum-bonded silicate according to claim 1, 2 or 3, wherein the transparency is 70% or more in the refractive index of the synthetic amorphous aluminum-bonded silicate in the range of 1.44 to 1.46. In the presence of a water-soluble alkali metal mineral salt electrolyte, a water-soluble aluminum salt and a mineral acid are added to the aqueous solution of the water-soluble alkali metal silicate and reacted to give a 5% by weight slurry pH of 8.0 to 10.0. The method for producing a synthetic amorphous aluminum-bonded silicate according to claim 1, wherein the method is adjusted as follows. The amount of the water-soluble alkali metal mineral salt electrolyte is 5 to 30% by mass with respect to SiO ₂ of the water-soluble alkali metal silicate as M ₂ O (wherein M represents an alkali metal). A method for producing the described synthetic amorphous aluminum-bonded silicate. The method for producing a synthetic amorphous aluminum-bound silicate according to claim 5 or 6, wherein the water-soluble aluminum salt is aluminum chloride, aluminum sulfate or aluminum nitrate.

Images