JPS6235963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing stabilized dicalcium phosphate dihydrate for toothpaste. Conventionally, dicalcium phosphate dihydrate has been used as a toothpaste base material due to its hardness, particle shape, etc. However, when dicalcium phosphate dihydrate is used as a base material for toothpaste, it partially dehydrates over time, solidifies and forms a coagulated mass, causing roughness on the toothpaste and making it difficult to remove from the tube. There have been problems such as increased polishing force that damages the tooth structure, and when aluminum is used for the tube, the aluminum material corrodes. Therefore, in order to prevent dehydration of dicalcium phosphate dihydrate, that is, to stabilize it, various stabilizers have been added to the dicalcium phosphate dihydrate. (U.S. Patent No.
No. 2018410), especially magnesium phosphate octahydrate. The present inventors have repeatedly researched dicalcium phosphate dihydrate as a toothpaste base material and magnesium phosphate as a stabilizer thereof, and have proposed the following combinations for each. are being conducted separately. In other words, for dicalcium phosphate dihydrate, which is the base material, the pH of the alkali metal phosphate and calcium salt is
A mixture of dicalcium phosphate dihydrate in columnar to plate-like crystals obtained by reacting at pH 2.5 to 3.5 and flat crystals obtained by reacting at pH 3.5 to 5.0, preferably 5:5 to 9:1.
It has been found that a mixture with a mixing ratio of is excellent in both polishing power and kneading properties. In addition, in producing a mixture of columnar to plate-like crystals and flat crystal dicalcium phosphate dihydrate, each is produced separately and the two are mixed, or an alkali metal phosphate and a calcium salt are heated at a reaction temperature. 40
℃ or below, the reaction is carried out at a pH of 2.5 to 3.5 in the first stage, and an alkaline substance is added in the second stage to raise the pH to 3.5 to 3.5.
We have also found that a more suitable method can be obtained by setting the value to 5.0. On the other hand, stabilizing magnesium phosphate has superior manufacturing methods and purity compared to anhydrous salt, tetrahydrate salt, octahydrate salt, and dodecyl salt, which have been known as magnesium phosphate, and is also suitable for use as a toothpaste base material. As an excellent stabilizing effect of dicalcium phosphate dihydrate, we have discovered and proposed a new magnesium phosphate that is amorphous and has a bound water content of octahydrate or less. This novel magnesium phosphate can be obtained by heating and dehydrating magnesium phosphate dodechydrate obtained by the reaction of an alkali metal phosphate and a magnesium salt. The present invention uses dicalcium phosphate dihydrate, which is a mixture of columnar to plate-like crystals and flat crystals, which is excellent as a base material for tooth brushing, and the above-mentioned amorphous, which has excellent properties as a stabilizer. quality and the amount of bound water is 8
The present invention relates to a method for producing stabilized dicalcium phosphate dihydrate for toothpaste using a novel magnesium phosphate that is less than hydrate. This columnar shape of dicalcium phosphate dihydrate
Simply mixing the mixture of plate crystals and flat crystals with the new magnesium phosphate has a weak stabilizing effect, so it is necessary to thoroughly mix the pre-pulverized dicalcium phosphate dihydrate and magnesium phosphate and then further crush the mixture. Good. The amount of magnesium phosphate added is 1 to 6% by weight, preferably 2 to 4% by weight based on dicalcium phosphate dihydrate.
If it is less than 1% by weight, no stabilizing effect can be obtained, and if it is added more than 6% by weight, no further effect can be expected, and if it is added in excess, the abrasive properties of dicalcium phosphate dihydrate , which is undesirable because it adversely affects physical properties such as kneading characteristics. In addition, as for the type of pulverization, a grinding type pulverizer such as a soaker is suitable, and if pulverizing is performed with an impact type pulverizer such as a pin type mill, thick dicalcium phosphate dihydrate can be obtained. However, this tends to become a thinner dicalcium phosphate dihydrate for toothpaste due to its expansion, and as a result,
This is similar to the case where only flat crystals were manufactured from the beginning. In addition, types such as ball mills and pipro mills that simultaneously perform grinding and impact are not preferred because dicalcium phosphate dihydrate adheres to the inner wall of the grinder, resulting in a very poor grinding efficiency. In order to obtain the optimal dicalcium phosphate dihydrate for toothpaste, the selection of the type of crusher is very important. Next, examples of manufacturing dicalcium phosphate dihydrate and novel magnesium phosphate used in the present invention, and examples in which combinations of these products were investigated will be given. Production example of dicalcium phosphate dihydrate 1 Sodium ammonium hydrogen phosphate (hereinafter referred to as phosphorus salt) produced from wet phosphoric acid was 7% P ₂ O ₅
Phosphate salt solution diluted with warm water to give 20%
A CaCl ₂ solution was continuously added to the first reaction tank at a Ca/p molar ratio of 1.10 and a reaction temperature of 30°C, and at the same time, a 35% HCl solution was added while adjusting the reaction pH to 2.7.
Furthermore, in the second reaction tank, 20% Ca(OH) ₂ slurry was added.
Adjust the pH to 4.3 and continuously obtain a slurry of monocalcium phosphate dihydrate. Then, it is separated from the mother liquor, washed,
It was dehydrated and dried at 50°C. This one has an average thickness
Most of the crystals are thick columnar to plate-like crystals of about 10 to 15 μm.
Some flat crystals with a thickness of about 1 to 2 μm were present. The mixing ratio of columnar (plate) crystals and flat crystals was 8:2. This micrograph is shown in FIG. Production example 2 14% P ₂ O ₅ phosphorus salt solution and 14% CaCl ₂ solution were mixed with Ca/p
Continuously added to the first reaction tank at a molar ratio of 1.10 and a reaction temperature of 30°C, simultaneously added 35% HCl solution to make the reaction pH 2.7, and further added 20% NaOH to the second reaction tank.
A slurry of dicalcium phosphate dihydrate is continuously obtained while adjusting the pH to 4.5 with a solution. Hereinafter, the same operations as in Production Example 1 were performed. The mixture ratio of the product obtained here was 8:2. Production example 3 14% P ₂ O ₅ phosphorus salt solution and 14% CaCl ₂ solution were mixed with Ca/p
Continuously added to the first reaction tank at a molar ratio of 1.00 and a reaction temperature of 35°C, and simultaneously added 35% HCl solution to make the reaction pH 3.3, and further added 20% dicalcium dihydrate to the second reaction tank. Obtain a slurry of Hereinafter, the same operations as in Production Example 1 were performed. The mixing ratio was 6:4. Production example 4 (comparative production example) 14% P ₂ O ₅ phosphorus salt solution and 14% CaCl solution were mixed with Ca/p
Add it to the reaction tank at a molar ratio of 1.10 and a reaction temperature of 30℃, and at the same time add 35% HCl solution so that the reaction pH becomes 2.7.
Continuously obtain dicalcium phosphate dihydrate slurry. The mother liquor was then separated, washed, dehydrated and dried at 50°C.
This material consisted of only columnar to plate crystals having an average thickness of about 10 to 15 μm. This micrograph is shown in FIG. Production Example 5 (Comparative Production Example) The reaction pH was set to 4.5 using the same procedure as Production Example 4.
The obtained crystals were only flat crystals with an average thickness of about 1 to 2 μm. This micrograph is shown in FIG. Manufacturing example of stabilizer magnesium phosphate 6 Add 10% magnesium sulfate solution dropwise to 10% sodium dihydrogen phosphate solution so that the Mg/P molar ratio is 1.5, making sure that the PH does not become 9 or less.
5N sodium hydroxide was also added dropwise at the same time. Note that the reaction temperature was 35°C and the reaction time was 1 hour. The generated large crystals of 50 to 150μ were filtered, washed, and dried at 40°C. This product showed the X-ray diffraction pattern shown in FIG. 4, and was confirmed to be magnesium phosphate 22-hydrate. Next, 100 g of dried magnesium phosphate 22 hydrate was spread thinly in a vat and dehydrated for 10 minutes at 150° C. in an internal heating dryer.
The weight of the dehydrated product was 62 g, and analysis revealed that the composition was approximately octahydrate. Moreover, the X-ray diffraction pattern of the dehydrated product showed the one shown in FIG. 4, confirming that it was amorphous. Production example 7 Add 5% magnesium chloride solution dropwise to 5% disodium hydrogen phosphate solution so that the Mg/P molar ratio is 1.5, making sure that the pH does not fall below 9.
5N sodium hydroxide was also added at the same time. Hereinafter, reaction, filtration, washing, and
Dry. This product was found to be magnesium phosphate 22-hydrate by X-ray diffraction. Spread 100g of this 22-hydrate salt thinly in a vat and heat it in an internal heating dryer at 100℃.
Dehydrated for 30 minutes. The dehydrated weight of this thing is 55
It was hot at g. As a result of analysis, the composition was almost hexahydrate. In addition, this product has X
It was confirmed by line diffraction that it was amorphous. Production Example 8 (Comparative Production Example) Add 20% phosphoric acid solution to 20% magnesium hydroxide slurry so that the Mg/P molar ratio is 1.5, and add N sodium hydroxide solution so that the PH does not become 9 or less. was added at the same time. Note that the reaction temperature is 50
℃, and the reaction time was 5 hours. The crystals thus obtained were extremely fine with an average grain size of about 1 to 5 microns, and the process required an excessively long time. After washing the crystals, they were dried at 80°C. The X-ray diffraction pattern of this product was shown in Figure 4-2, and it was confirmed that it was magnesium phosphate octahydrate crystals. Production Example 9 (Comparative Production Example) Magnesium phosphate obtained in the same manner as Production Example 6
100 g of 22-hydrate salt was spread thinly in a vat and dehydrated at 80°C for 40 minutes in an internal heating dryer. The weight of the dehydrated product was 67 g, and the amount of bound water was approximately 10 hydrate. This material was confirmed to be amorphous by X-ray diffraction. Examples and Comparative Examples The dicalcium phosphate dihydrate produced in Production Examples 1, 2, 3, 4, and 5 and the magnesium phosphate produced in Production Examples 6, 7, 8, and 9, or the reagent sodium pyrophosphate were used. Add a certain amount, mix and crush with a pickling machine,
Table 1 shows the results of physical property tests and stability tests using samples that passed 350#. In addition, the physical property test was conducted as follows. (a) Average particle size...by air permeation method. (b) Bulk specific gravity...value measured after 50 tappings using a powder tester scent manufactured by Hosokawa Iron Works. (c) Dispersibility: Make a paste of the sample and 80% glycerin and measure using a JISK-5101 grind meter. (d) Condition of kneading: Condition when sample and 80% glycerin are squeezed. (e) Oil absorption: Knead 30g of sample with 80% glycerin,
The amount of glycerin when a certain viscosity is reached. (f) Polishing power: Weight loss when a sample is suspended in a 30% glycerin solution and an Al piece is polished for a certain period of time using a toothbrush of constant hardness in the suspension. In the stability test, 30g of the sample and 20g of 80% glycerin were kneaded into a test tube, and the condition was observed and evaluated after standing at each temperature for each period of time. The evaluation display symbols are as follows. ◎ The viscosity of the specimen before and after the test does not change at all 〇 Compared to before the test, it is slightly solidified and the viscosity has increased △ It is solidified and has almost no fluidity × It is solidified and has no fluidity at all 【table】

[Brief explanation of the drawing]

Figures 1, 2 and 3 are microscopic photographs of dicalcium phosphate dihydrate, with Figure 1 being of the present invention and Figures 2 and 3 being comparative examples. FIG. 4 is an X-ray diffraction pattern of magnesium phosphate of the present invention and for comparison, and 1 is the one of the present invention.

Claims (1)

[Scope of Claims] 1 (A) The ratio of dicalcium phosphate dihydrate in plate-like to columnar crystals to dicalcium phosphate dihydrate in flat crystals is 5:5 to 5:5.
dicalcium phosphate dihydrate consisting of a 9:1 mixture;
(B) Magnesium phosphate, which has a composition in which the amount of bound water is octahydrate or less, and is amorphous, is used in a range of 1 to 6% by weight of the above-mentioned magnesium phosphate based on the above-mentioned dicalcium phosphate dihydrate. A method for producing stabilized dicalcium phosphate dihydrate for toothpaste, which comprises mixing and then pulverizing. 2. Platy to columnar crystals obtained by reacting alkali metal phosphate and calcium at a reaction temperature of 40°C or lower, with a pH of 2.5 to 3.5 in the first stage, and a pH of 3.5 to 5.0 in the second stage. A method for producing stabilized dicalcium phosphate dihydrate for toothpaste according to claim 1, which uses dicalcium phosphate dihydrate consisting of a mixture of flat crystals.