JP2020169110A - Synthetic amorphous aluminum-zinc bonded silicate - Google Patents

Abstract

To further improve the functionality of a conventional synthetic amorphous aluminum-bonded silicate.SOLUTION: A zinc-containing synthetic amorphous aluminum-bonded silicate (synthetic amorphous aluminum-zinc bonded silicate) is characterized by fulfilling five specific requirements (aluminum content, 5 mass% slurry pH, pore size, OH group content, zinc content). The synthetic amorphous aluminum-zinc bonded silicate has a higher cleanability than conventional synthetic amorphous aluminum-bonded silicates.SELECTED DRAWING: None

Description

The present invention relates to an abrasive for toothpaste, and more specifically to a synthetic amorphous aluminum-bonded silicate containing zinc (hereinafter referred to as "synthetic amorphous aluminum-zinc-bonded silicate").

Patent Document 1 discloses a technique relating to a synthetic amorphous aluminum-bonded silicate having low abrasiveness and high cleanability that does not damage teeth, and excellent storage stability of high transparency and transparency as a transparent silica base for toothpaste. It is disclosed.

Further, Patent Documents 2 to 4 disclose dentifrice compositions using the synthetic amorphous aluminum-bonded silicate.

Japanese Patent No. 4785068 Japanese Unexamined Patent Publication No. 2010-275271 Japanese Unexamined Patent Publication No. 2010-275272 Japanese Unexamined Patent Publication No. 2010-275273

The synthetic amorphous aluminum-bonded silicate described in Patent Document 1 is excellent in storage stability of high transparency and transparency, and has low abrasiveness and high cleanability that does not damage the teeth required for a transparent silica base for toothpaste. It has a high degree of technical perfection.

An object of the present invention is to further improve the functionality of the synthetic amorphous aluminum-bonded silicate described in Patent Document 1. However, regarding transparency, it cannot be said that the demand for dentifrice is high, so functions other than transparency are targeted.

As a result of diligent studies on the above-mentioned problems, the present inventors have found a surprising fact that further high cleaning property can be obtained by adding zinc to the synthetic amorphous aluminum-bonded silicate described in Patent Document 1. The present invention has been completed based on such findings.

The present invention is as follows.
[1] A synthetic amorphous aluminum-zinc-bonded silicate having all the following characteristics (1) to (5).
(1) Aluminum is in the range of 0.5 to 7.5% by mass with respect to SiO ₂ as Al ₂ O ₃ .
(2) The pH of the 5% by mass slurry is in the range of 8.0 to 10.0.
(3) The pore diameter is in the range of 1.5 to 4.0 nm.
(4) The amount of OH groups is in the range of 2.5 to 8.0% by mass with respect to SiO ₂ .
(5) Zinc as ZnO is in the range of 0.02 to 1.0% by mass with respect to SiO ₂ .
[2] Water-soluble alkali metal mineral acid The by-product is removed after reacting the water-soluble alkali metal silicate, the water-soluble aluminum salt, the water-soluble zinc compound and the mineral acid in the presence of the electrolyte. The method for producing a synthetic amorphous aluminum-zinc bonded silicate according to the above [1], which comprises the step.

Hereinafter, the present invention will be described in detail based on preferred embodiments, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the claims.
In the present invention, the notation "numerical value 1 to numerical value 2" regarding the numerical value range means a numerical value range including the numerical values 1 and 2 at both ends, with the numerical value 1 as the lower limit and the numerical value 2 as the upper limit. It is synonymous with "numerical value 1 or more and numerical value 2 or less".

(Synthetic amorphous aluminum-zinc bonded silicate)
The synthetic amorphous aluminum-zinc-bonded silicate of the present invention (hereinafter abbreviated as "Al-Zn-bonded silicate") has all the following characteristics (1) to (5).
(1) Aluminum is in the range of 0.5 to 7.5% by mass with respect to SiO ₂ as Al ₂ O ₃ .
(2) The pH of the 5% by mass slurry is in the range of 8.0 to 10.0.
(3) The pore diameter is in the range of 1.5 to 4.0 nm.
(4) The amount of OH groups is in the range of 2.5 to 8.0% by mass with respect to SiO ₂ .
(5) Zinc as ZnO is in the range of 0.02 to 1.0% by mass with respect to SiO ₂ .

Synthetic amorphous aluminum-bonded silicates (hereinafter abbreviated as "Al-bonded silicates") are described in Patent Documents 1 to 4 in the presence of a water-soluble alkali metal mineral salt electrolyte. , It is obtained by reacting a water-soluble alkali metal silicate, a water-soluble aluminum salt, and a mineral acid. Since the Al-Zn-linked silicate contains zinc in the Al-linked silicate, it also has the characteristics (1) to (4) that the Al-linked silicate had, and further, the amount of zinc. It has the characteristic (5) related to. It is unclear in what form zinc is contained in the Al-Zn-linked silicate, but for example, the form in which zinc is contained in the Al-linked silicate, at least a part of the Al-linked silicate. A form coated with zinc, a form in which these coexist, and the like can be considered.

The range of aluminum content in the Al-Zn-bonded silicate in the property (1) is defined from the viewpoint of abrasiveness. This range is preferably in the range of 1.0 to 6.0% by mass, and more preferably in the range of 1.5 to 4.5% by mass.

The method for measuring the pH of the 5% by mass slurry of characteristic (2) is to put 5 g of Al-Zn-bonded silicate in 95 ml of deionized water and stir to prepare a suspension. The pH value is read after 2 minutes of stirring by the pH measurement method of. The pH range of the 5% by mass slurry pH is preferably in the range of 9.0 to 10.0.

The method for measuring the pore size of Al-Zn-linked silicate in property (3) is to use BELSORP MINI manufactured by Nippon Bell Co., Ltd., use liquid nitrogen as a coolant, and adsorb nitrogen gas at -196 ° C. The pore size distribution is calculated from the amount of nitrogen gas adsorbed by the Dollimore-Heal method, and the maximum frequency diameter is used as the pore size. Degassing is performed at 120 ° C. for 60 minutes.

The method for measuring the amount of OH groups in the Al-Zn-bonded silicate in the characteristic (4) is to use Thermo Plus EVO2 manufactured by Rigaku Co., Ltd. and use the following formula according to the weight change between 190 ° C and 900 ° C. Calculate OH / SiO ₂ (% by mass) and use this as the amount of OH groups. The amount of OH groups shall be the same as the amount of water released between 190 ° C and 900 ° C.
Formula: OH / SiO ₂ (mass%) = (mass after firing at 190 ° C-mass after firing at 900 ° C) / mass after firing at 190 ° C

The Al-bonded silicate has low abrasiveness and high cleanability that does not damage the teeth. The property (5) contributes to further improving the high cleaning property of the Al-bonded silicate while having the same low abrasiveness as the Al-bonded silicate. The range of zinc content in the Al-Zn-linked silicate in the property (5) is preferably in the range of 0.05 to 0.5% by mass, and more preferably in the range of 0.05 to 0.1% by mass.

Generally, the RDA (Radioactive Dentin Abration) method is known as a method for evaluating the abrasiveness of a toothpaste, and the tobacco tar method is known as a method for evaluating the cleanability, but the evaluation method is complicated. In addition, the following evaluation indexes are used in the present invention because of problems such as high cost.

The evaluation index of polishability is the weight loss of gold-silver-palladium alloy plate polishing. Castwell M.C. 12% GOLD manufactured by GC is used as the gold-silver-palladium alloy plate. The measurement method is to use a horizontal reciprocating brushing grinder, place a 60 mass% glycerin aqueous solution containing Al-Zn-bonded silicate as 15 mass% on a gold-silver-palladium alloy plate, apply a load of 400 g, and stroke 20 mm. After polishing 10,000 times, the weight loss of the gold-silver-palladium alloy plate is measured. The polishing weight loss is preferably 1.0 mg or less because low polishing property is desired.

The evaluation index of cleanability is the weight loss of copper plate polishing. To measure the weight loss by polishing the copper plate, use a horizontal reciprocating brushing type grinder, place a 60 mass% glycerin aqueous solution containing Al-Zn-bonded silicate as 15 mass% on a smooth surface copper plate, and apply a load of 400 g. After polishing 20,000 times with a stroke of 20 mm, the weight loss of the copper plate is measured, and this is used as the copper plate polishing weight loss. It can be evaluated that the larger the copper plate polishing weight loss, the higher the cleaning power.

A preferred form of Al-Zn-conjugated silicate is one with a transparency of 50% or higher. In this method of measuring transparency, D-sorbitol and water are mixed in appropriate amounts to prepare dispersion media with various refractive indexes, and 2 g of Al-Zn-bonded silicate is dispersed as a sample in 18 g of each dispersion medium, and vacuum is applied. Degas. Measure the refractive index and transparency (wavelength 590 nm, optical path length 10 mm) of this mixture at 25 ° C, draw a refractive index-transparency curve, and use the refractive index of the mixture when the transparency is maximized as the refractive index of the sample. The transparency at that time is defined as the transparency of the sample.

(Production method)
A suitable method for producing an Al-Zn-linked silicate is to combine a water-soluble alkali metal silicate, a water-soluble aluminum salt, a water-soluble zinc compound and a mineral acid in the presence of a water-soluble alkali metal mineral acid electrolyte. It includes a step of removing by-products after the reaction.

In the above step, as a specific example of the reaction operation, a water-soluble alkali metal silicate and a water-soluble alkali metal mineral acid electrolyte are charged into the reaction vessel, and a water-soluble aluminum salt, a water-soluble zinc compound and a mineral acid are added thereto. It is added at the same time or separately and reacted. In order to proceed smoothly with the reaction, heating is preferable, and the heating temperature is preferably in the range of 60 to 100 ° C. Moreover, it is preferable that the pH at the end of the reaction is in the range of 6 to 9.

In the above step, a specific example of the operation for removing by-products is washing with water. Further, filtration may be performed before washing, and a method in which the wet cake obtained by filtration is dispersed in a water amount several times larger than that and washed is a good example. By-products are those that deviate from the composition of Al-Zn-linked silicates, and include unreacted products derived from raw materials, salts produced by the reaction, and ions thereof. The degree of removal of by-products may be within a range that does not interfere with the use as a dentifrice abrasive, and it is not necessary to completely remove the by-products.

After the above step, as an arbitrary step, a pH adjusting step of adjusting the pH with an acid or an alkali may be provided so that the obtained Al-Zn-bonded silicate satisfies the characteristic (2). A good example of the acid here is a mineral acid, and a good example of an alkali is a hydroxide, carbonate, or bicarbonate of sodium. Further, as an arbitrary step, a step of recovering the Al—Zn-linked silicate as a solid content may be provided. A known method such as filtration or drying can be used for the recovery.

Preferable examples of water-soluble alkali metal mineral acid electrolytes are sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, potassium nitrate and the like. As a method of its use, it is preferable to preliminarily contain a water-soluble alkali metal mineral acid electrolyte in a water-soluble alkali metal silicate solution. The amount used is preferably in the range of 5 to 30% by mass with respect to SiO ₂ of the water-soluble alkali metal silicate as M ₂ O (where M indicates an alkali metal). This range is suitable for Al-Zn-linked silicates to have low abrasiveness.

Preferable examples of the water-soluble alkali metal silicate are sodium silicate, potassium silicate, lithium silicate and the like, but sodium silicate is preferable from the viewpoint of relatively low cost. The amount used is preferably in the range of 2 to 4 as the molar ratio of SiO ₂ / M ₂ O (where M indicates an alkali metal). When using a water-soluble alkali metal silicate solution, it is preferable that the SiO ₂ concentration is in the range of 5 to 15% by mass.

A good example of the water-soluble aluminum salt is aluminum chloride, aluminum sulfate, aluminum nitrate and the like. The amount of Al ₂ O ₃ used is preferably in the range of 0.5 to 7.5% by mass, more preferably in the range of 1.0 to 6.0% by mass, based on SiO ₂ of the water-soluble alkali metal silicate.

Preferable examples of water-soluble zinc compounds are zinc sulfate, zinc chloride, zinc nitrate and the like. The amount used is preferably in the range of 0.05 to 0.5% by mass with respect to SiO ₂ as ZnO.

By appropriately designing the amounts of the water-soluble aluminum salt and the water-soluble zinc compound, the desired high cleaning property can be obtained. For example, it is preferred values obtained by multiplying the ZnO / SiO ₂ (wt%) to Al ₂ O ₃ / SiO ₂ (wt%) is in the range of 0.05 to 3. The lower limit of the above range is more preferably 0.1. The upper limit is more preferably 2.5, and even more preferably 2.

The mineral acid acts as an acidifying agent for the water-soluble alkali metal silicate, and good examples are hydrochloric acid, sulfuric acid, nitric acid and the like. The concentration of the mineral acid is preferably in the range of 5 to 25% by mass, more preferably in the range of 10 to 20% by mass.

Since the Al-Zn-linked silicate has excellent properties as a dentifrice abrasive, it can be suitably used as a raw material for a dentifrice.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[Examples 1 to 5]
10 kg of 10 mass% sodium silicate (Na ₂ O · 3.14SiO ₂ ) aqueous solution was placed in a 20 L reaction vessel with a baffle plate equipped with a stirrer with a 150 mmφ turbine blade, and sodium chloride was added to this as Na ₂ O / SiO _2. The mixture was mixed so as to have a concentration of 6.4% by mass, and the reaction temperature was maintained at 95 ° C. Further, a mixed solution of 8 mass% Al ₂ O ₃ aluminum sulfate aqueous solution, 8 mass% ZnO zinc sulfate aqueous solution and 10 mass% sulfuric acid was added at a rate of 50 ml / min so as to have the ratio shown in Table 1, and then 10 Mass% sulfuric acid was added until pH 6.5. Next, the resulting slurry was filtered and the resulting wet cake was washed. When the slurry pH was measured during this washing, the pH was around 8.0. Then, it was filtered and dried to produce Al-Zn-bonded silicates of Examples 1 to 5.

[Reference Example 1]
It was produced under the same conditions as in Example 1 except that an aqueous zinc sulfate solution was not added, to obtain an Al-bonded silicate.

When the component compositions of the Al-Zn-bonded silicates of Examples 1 to 5 and the Al-bonded silicates of Reference Example 1 were analyzed, they were almost as prepared. As a result, the Al-Zn-bonded silicates of Examples 1 to 5 all satisfied the properties (1) and (5), and the Al-bonded silicates of Reference Example 1 satisfied the property (1). ..

The following analysis was performed on the Al-Zn-bonded silicates of Examples 1 to 5 and the Al-bonded silicates of Reference Example 1, and the results are shown in Table 2. In the following description of each analysis, "sample" means the above-mentioned Al-Zn-linked silicate or Al-linked silicate.
・ 5% by mass slurry pH
5 g of the sample was placed in 95 ml of deionized water and stirred to prepare a suspension, and the pH value was read after 2 minutes of stirring by the pH measurement method of the quasi-drug raw material standard general test method.
・ Pore size Using BELSORP MINI manufactured by Nippon Bell Co., Ltd., liquid nitrogen is used as a coolant, nitrogen gas is adsorbed on the sample at -196 ° C, and the pore size is distributed by the Dollimore-Heal method from the amount of nitrogen gas adsorbed. Was calculated, and the maximum frequency diameter thereof was taken as the pore diameter. Degassing was performed at 120 ° C. for 60 minutes.
・ OH group amount
Using Thermo Plus EVO2 manufactured by Rigaku Co., Ltd., OH / SiO ₂ (mass%) was calculated using the following formula based on the weight change of the sample between 190 ° C and 900 ° C, and this was used as the OH group amount. The amount of OH groups was the same as the amount of water released between 190 ° C and 900 ° C.
Formula: OH / SiO ₂ (mass%) = (mass after firing at 190 ° C-mass after firing at 190 ° C) / mass after firing at 190 ° C / polishability Gold-silver-palladium alloy plate (Castwell MC 12% GOLD manufactured by GC) Rectangular . The size of one sheet is about 13 mm on the long side and about 8 mm on the short side), and a glass container (inner dimensions: length 62 mm x width 28 mm x height 10.5 mm) so that the short sides touch each other. A gold-silver-palladium alloy test plate (long side about 48 mm, short side about 13 mm) was placed and fixed on the bottom surface of the.
10 g of a 60 mass% glycerin aqueous solution containing a sample as 15 mass% was placed on the test plate, and a load of 400 g was applied to a toothbrush (Gum Dental Brush # 211 manufactured by Sunstar Co., Ltd.) to form a long side of the test plate. After polishing the test plate 10,000 times with a stroke of 20 mm in the parallel direction, the weight loss of the test plate was measured.
・ Cleanability Place 10 g of a 60 mass% glycerin aqueous solution containing a sample as 15 mass% on a smooth surface copper plate fixed to the bottom of a glass container (inner dimensions: length 62 mm x width 28 mm x height 10.5 mm), and use a toothbrush (((()) A load of 400 g was applied to a Dent Inclear Wind SV manufactured by UFC Supply Co., Ltd., and after polishing 20,000 times with a stroke of 20 mm, the weight loss of the copper plate was measured. It can be evaluated that the larger the weight loss, the higher the cleaning power.
・ Refractive index, transparency
An appropriate amount of D-sorbitol and water were mixed to prepare dispersion media having various refractive indexes, and 2 g of the sample was dispersed in 18 g of each dispersion medium and evacuated by vacuum. 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 maximized is the refractive index of the sample, and the transparency at that time is the transparency of the sample. did. An Appe refractive index meter manufactured by Atago Co., Ltd. was used for measuring the refractive index, and V-670 manufactured by JASCO Corporation was used for measuring the transparency. The wavelength in the transparency measurement was 590 nm, and a transparent cell with an optical path length of 10 mm was used.

As shown in Table 2, the Al-Zn-bonded silicates of Examples 1 to 5 and the Al-bonded silicates of Reference Example 1 both satisfied the properties (2) to (4).

Regarding the polishability, the Al-Zn-bonded silicates of Examples 1 to 5 and the Al-bonded silicates of Reference Example 1 showed almost the same polishing values. Moreover, those polishing values can be said to be low polishing properties.

On the other hand, regarding the cleanability, the Al-bonded silicate of Reference Example 1 had a high cleanability, but the Al-Zn-bonded silicates of Examples 1 to 5 had a higher cleanability than that. It turned out to be.

Claims (2)

It is a synthetic amorphous aluminum-bonded silicate containing zinc (hereinafter referred to as "synthetic amorphous aluminum-zinc-bonded silicate").
A synthetic amorphous aluminum-zinc bonded silicate having all of the following characteristics (1) to (5).
(1) Aluminum is in the range of 0.5 to 7.5% by mass with respect to SiO ₂ as Al ₂ O ₃ .
(2) The pH of the 5% by mass slurry is in the range of 8.0 to 10.0.
(3) The pore diameter is in the range of 1.5 to 4.0 nm.
(4) The amount of OH groups is in the range of 2.5 to 8.0% by mass with respect to SiO ₂ .
(5) Zinc as ZnO is in the range of 0.02 to 1.0% by mass with respect to SiO ₂ . A step of reacting a water-soluble alkali metal silicate, a water-soluble aluminum salt, a water-soluble zinc compound, and a mineral acid in the presence of a water-soluble alkali metal mineral acid electrolyte, and then removing by-products.
The method for producing a synthetic amorphous aluminum-zinc-bonded silicate according to claim 1.