A strontium / potassium polyaspartate and a method for its preparation and use

Abstract

The application discloses a kind of polystrontium aspartate / potassium and its preparation method and application, belong to daily chemical technical field.The polystrontium aspartate / potassium using poly succinimide can be prepared in the aqueous solution of strontium hydroxide and potassium hydroxide hydrolysis.The preparation process has the characteristics of mild conditions, simple process, low cost, high efficiency and environmental protection.The polystrontium aspartate / potassium provided by the application is used for whitening and anti-allergic toothpaste, has the dual effect of moisturizing and whitening and anti-allergic, compared with adding poly sodium aspartate and potassium chloride, strontium chloride respectively, the use of polystrontium aspartate / potassium eliminates a large number of sodium ions and chloride ions, effectively reduces the ion concentration in formula, reduces formula difficulty.

Description

Technical Field

[0001] This invention belongs to the field of daily chemical products technology, specifically relating to a polyaspartic acid strontium / potassium, its preparation method, and its application. Background Technology

[0002] Desensitizing agents are added to anti-sensitivity toothpaste as active ingredients. Common desensitizing agents include fluoride, silver salts, potassium salts, and strontium salts. Strontium ions, in particular, have an adsorption capacity for all calcified tissues, including dentin. They enter the dentinal tubules and react with calcium in the hard dental tissue to form strontium apatite, which is then deposited on the tubule walls, sealing open dentinal tubules and preventing tooth sensitivity. Potassium ions act on the nerve endings in the dentinal tubules, altering the ion gradient and changing the resting membrane potential of nerve cells. This depolarizes the sensory nerves in the dental pulp, thus interrupting pain transmission.

[0003] Polyaspartic acid can not only act as a humectant, but also reduce the adhesion of bacteria to hydroxyapatite through the chelation of metals by its side chains, thereby reducing the number of plaques on the tooth surface; and it can also block calcium ions at physiological pH, inhibiting the precipitation of calcium phosphate salts, ultimately achieving the effects of reducing tartar, inhibiting dental plaque, and reducing tooth staining.

[0004] In the manufacturing process of anti-sensitivity toothpaste, abrasives, humectants, thickeners, foaming agents, flavorings, desensitizing agents, water, and other additives are mixed. Generally, potassium and strontium are incorporated into the formula as soluble salts such as potassium chloride and strontium chloride, while polyaspartic acid is added as sodium polyaspartate. Therefore, to achieve the anti-sensitivity and moisturizing effects of toothpaste, the formula contains a large number of potassium ions, strontium ions, chloride ions, sodium ions, and carboxylate ions from the side chains of polyaspartic acid. This presents challenges in selecting and using thickeners, choosing foaming agents and achieving optimal foaming effects, as well as determining the whitening and anti-sensitivity effects of the toothpaste.

[0005] Therefore, how to reduce ionic strength, thereby reducing the difficulty of toothpaste formulation and enhancing whitening and anti-sensitivity effects, is one of the problems that anti-sensitivity toothpaste needs to solve. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a polyaspartic acid strontium / potassium, its preparation method, and its applications. The provided polyaspartic acid strontium / potassium is prepared by hydrolyzing polysuccinimide (PSI) in an aqueous solution of potassium hydroxide and strontium hydroxide. This production method features mild production conditions, simple process, low cost, high efficiency, and environmental friendliness. The product, polyaspartic acid strontium / potassium, possesses dual effects of moisturizing and whitening, as well as anti-allergy properties. Furthermore, compared to separately adding sodium polyaspartate and potassium chloride / strontium chloride, it eliminates the need for large amounts of sodium and chloride ions, effectively reducing the ion concentration in the formulation and simplifying the formulation process.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] One of the technical solutions of this invention is to provide a polyaspartic acid strontium / potassium, the structural formula of which is as follows:

[0009]

[0010] Where x+y+m+n=25~440, and (m+n):(x+y)=1:4~100.

[0011] The compound with the above structure can also be named "polyaspartic strontium / potassium" or "polyaspartic strontium / potassium".

[0012] The second technical solution of the present invention provides a method for preparing the above-mentioned polyaspartic strontium / potassium, comprising the following steps:

[0013] Polysuccinimide, strontium hydroxide, and potassium hydroxide were mixed in water and hydrolyzed to obtain the polyaspartic acid strontium / potassium.

[0014] The molar ratio of succinimide units, strontium hydroxide, and potassium hydroxide in the polysuccinimide is 1:a:b, wherein a and b satisfy 0.9≤a+b≤1.2 and 1≤2a+b, and a:b=1:2~50.

[0015] The polyaspartic acid strontium / potassium prepared according to the above method contains 3.5–8.0 wt% strontium and 18.0–25.0 wt% potassium.

[0016] The raw material used in this invention, "polysuccinimide," is also known as "polysuccinimide."

[0017] Preferably, the number-average molecular weight of the polysuccinimide is 3 to 50 kDa.

[0018] Preferably, the mass ratio of the polysuccinimide to the water is 1:4 to 10.

[0019] Preferably, the hydrolysis reaction is carried out at a temperature of 20–60°C for 1–4 hours.

[0020] Preferably, the hydrolysis reaction is followed by a purification step, which specifically includes: adjusting the pH of the reaction system to 8.0-9.0, then ultrafiltration and drying to obtain the polyaspartic acid strontium / potassium.

[0021] Preferably, the acid used to adjust the pH value includes one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, lactic acid, citric acid, malic acid, succinic acid, and tartaric acid.

[0022] The third technical solution of the present invention provides an application of the above-mentioned polyaspartic strontium / potassium in the preparation of whitening and anti-sensitivity toothpaste.

[0023] The fourth technical solution of the present invention provides a whitening and anti-sensitivity toothpaste, wherein the anti-sensitivity and whitening functional ingredients are the above-mentioned polyaspartic acid strontium / potassium.

[0024] The beneficial technical effects of the present invention are as follows:

[0025] The preparation process of polyaspartic acid strontium / potassium provided by this invention has the characteristics of mild conditions, simple process, low cost, high efficiency and environmental protection.

[0026] The strontium / potassium polyaspartate provided by this invention is used in whitening and anti-sensitivity toothpaste, which has the dual effects of moisturizing and whitening as well as anti-sensitivity. Compared with the separate addition of sodium polyaspartate and potassium chloride and strontium chloride, the use of strontium / potassium polyaspartate eliminates the need for a large number of sodium ions and chloride ions, effectively reducing the ion concentration in the formula and reducing the difficulty of formulating. Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0028] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0029] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] The detection instruments and methods involved in the embodiments are as follows:

[0033] pH values ​​were measured using a Mettler Toledo SevenDirect SD20.

[0034] The strontium content was determined by flame atomic absorption spectrometry in accordance with the light industry standard QB / T 2968-2021 "Method for Determination of Strontium Content in Toothpaste for Oral Hygiene Products".

[0035] The potassium content was determined by flame atomic absorption spectrometry after dilution, in accordance with the national standard GB / T 17767.3-2010 "Determination of Organic-Inorganic Compound Fertilizers - Part 3: Total Potassium Content".

[0036] The anti-sensitivity and whitening effects of polyaspartic acid strontium / potassium were analyzed and compared using in vitro efficacy evaluation methods such as dentin permeability test and tooth stain removal ability test.

[0037] In this embodiment of the invention, "room temperature" refers to a temperature of 25±5℃.

[0038] Examples 1-11

[0039] Preparation of Strontium / Potassium Polyaspartic Acid:

[0040] Add an accurate amount of deionized water to a beaker, then add an accurate amount of Sr(OH)2; stir thoroughly until the Sr(OH)2 is completely dissolved, then add an accurate amount of KOH and stir to mix evenly at room temperature; then add an accurate amount of PSI to the resulting mixed solution, and react at room temperature for 2 hours with stirring, then filter to remove insoluble matter to obtain a brownish-yellow aqueous solution.

[0041] The pH of the above brownish-yellow aqueous solution was adjusted to 8.0-9.0 with 1 mol / L hydrochloric acid solution. The solution was then ultrafiltered through a filter membrane with a molecular weight cutoff of 3 kDa and the concentrate was collected to obtain a polyaspartic acid strontium / potassium aqueous solution. The obtained polyaspartic acid strontium / potassium aqueous solution was freeze-dried to obtain a pale yellow to yellow powder, which is polyaspartic acid strontium / potassium.

[0042] The specific process parameters and product test results for the above process are detailed in Table 1.

[0043] Table 1

[0044]

[0045] Example 12

[0046] The stability of the preparation process of polyaspartic strontium / potassium was investigated:

[0047] The process method of Example 1 was used to conduct five consecutive repeatable experiments, and the product test results are shown in Table 2.

[0048] Table 2

[0049] serial number 1 2 3 4 5 RSD (%) Strontium content (wt%) 6.10 6.15 6.08 6.21 6.11 0.84 Potassium content (wt%) 21.79 21.81 21.94 21.81 21.73 0.35

[0050] As can be seen from the RSD in Table 2, the preparation process of polyaspartic acid strontium / potassium provided by the present invention is relatively stable.

[0051] Example 13

[0052] Scale-up of the preparation process of polyaspartic strontium / potassium:

[0053] Based on the process method of Example 1, an industrial-scale preparation of polyaspartic acid strontium / potassium was carried out. Specifically, 72.0 L of deionized water was added to a 100 L reaction vessel. While stirring, 1.84 kg of Sr(OH)₂ was slowly added. After complete dissolution, 6.87 kg of KOH was added and thoroughly stirred, dissolved, and mixed. After the mixed solution returned to room temperature, 12 kg of PSI was slowly added while stirring, and stirring continued for 2 hours to obtain a brownish-yellow aqueous solution.

[0054] After removing insoluble matter by passing the obtained brownish-yellow aqueous solution through a pipeline filter, the pH was adjusted to 8.0 with 1 mol / L hydrochloric acid aqueous solution, and then ultrafiltered through a filter membrane with a molecular weight cutoff of 3 kDa. The concentrated solution was taken to obtain polyaspartic acid strontium / potassium aqueous solution. The obtained polyaspartic acid strontium / potassium aqueous solution was spray-dried to obtain a light yellow powder, which is polyaspartic acid strontium / potassium.

[0055] Upon testing, the strontium content in the polyaspartic acid strontium / potassium product prepared in Example 13 was 6.10 wt%, and the potassium content was 21.90 wt%, which was very close to that in Example 1.

[0056] Example 14

[0057] Preparation of whitening and anti-sensitivity toothpaste:

[0058] Based on the polyaspartic acid strontium / potassium prepared in Example 1, whitening and anti-sensitivity toothpaste was prepared according to the formulation in Table 3.

[0059] Table 3

[0060]

[0061] Comparative Example 1

[0062] Preparation of whitening toothpaste:

[0063] Whitening toothpaste was prepared according to the formula in Table 4, using hydrogen peroxide and titanium dioxide as whitening agents.

[0064] Table 4

[0065]

[0066]

[0067] Comparative Example 2

[0068] Preparation of anti-sensitivity toothpaste:

[0069] Anti-sensitivity toothpaste was prepared according to the formula in Table 5, using potassium nitrate and hydroxyapatite as anti-sensitivity ingredients.

[0070] Table 5

[0071]

[0072] Example 15

[0073] In vitro efficacy evaluation experiment for anti-allergy effects (dentin permeability test using conductivity method)

[0074] The greater the degree of opening of dentinal tubules, the stronger the permeability, and the higher the tooth sensitivity. The permeability of dentin samples can be assessed by measuring their electrical conductivity, thus characterizing the effect of the test sample on tooth sensitivity.

[0075] Experimental methods: 1) Using a diamond slicer, extracted human third molars were cut into dentin slices 1-2 mm thick. Enamel and cementum were then removed to expose the dentin surface. The slices were washed with distilled water to remove debris and set aside. 2) The whitening and desensitizing toothpaste prepared in Example 14 was evenly applied to the surface of the treated dentin slices as samples. 3) The samples were fixed in the testing device, with both ends in contact with electrodes, and immersed in physiological saline at 37°C for 10 minutes. The initial conductivity value was recorded using a conductivity meter, and then the conductivity was recorded every 5 minutes for 30 minutes.

[0076] Dentin slices without toothpaste coating were used as blank controls, whitening toothpaste prepared in Comparative Example 1 was used as negative controls, and anti-sensitivity toothpaste prepared in Comparative Example 2 was used as positive controls. The conductivity measurement results of each group are shown in Table 6.

[0077] Table 6

[0078]

[0079] As shown in Table 6, the whitening and desensitizing toothpaste prepared by the present invention has excellent desensitizing properties. Furthermore, compared with commonly used desensitizing ingredients, the polyaspartic acid strontium / potassium prepared by the present invention has a better desensitizing effect on teeth.

[0080] Example 16

[0081] Evaluation of whitening efficacy in vitro (teeth stain removal ability test)

[0082] By contacting hydroxyapatite with common external staining sources of teeth, the effects of chemical decolorization, bleaching, oxidation, and adsorption in the teeth whitening formula after tooth matrix staining are simulated. The absorbance values ​​of the staining source solution before and after the action of the teeth whitening components are tested, and the stain removal power of the teeth whitening components on typical staining sources that pollute the cleanliness of teeth, such as coffee stains, tea stains, red wine stains, and tobacco stains, can be calculated.

[0083] Experimental methods:

[0084] 1) Main reagents: Hydroxyapatite (particle size 80μm); Oolong tea (add a small amount of commercially available oolong tea to an appropriate amount of boiling water, steep for 15 minutes, then filter and set aside; must be used within 3 hours), Coffee (add a small amount of commercially available coffee beans to an appropriate amount of boiling water, steep for 15 minutes, then filter and set aside; must be used within 3 hours), Tobacco extract (after removing the filter and cigarette paper from commercially available cigarettes, add the extracted tobacco to an appropriate amount of boiling water, steep for 15 minutes, then filter and set aside; must be used within 3 hours), Red wine (freshly opened commercially available red wine within 3 hours); Hydrochloric acid solution (1mol / L); Sample solution (0.3wt% Strontium / Potassium polyaspartate aqueous solution of Example 1, fully dissolved and filtered through a 0.22μm filter membrane for use), Reference solution (0.3wt% Sodium polyaspartate aqueous solution, fully dissolved and filtered through a 0.22μm filter membrane for use).

[0085] 2) Testing Procedure: After rinsing, hydroxyapatite was added to tea extract, coffee extract, tobacco extract, and red wine staining source, respectively. The mixture was thoroughly mixed to ensure complete staining of the hydroxyapatite, and excess staining source was removed. The stained hydroxyapatite was then eluted with hydrochloric acid solution to obtain the hydrochloric acid eluent. This eluent was used as a calibration solution to measure the absorbance of each sample. The absorbance (AL) of the hydrochloric acid eluent was measured using a spectrophotometer, and the AL value was 0.

[0086] Hydroxyapatite was rinsed and then mixed with tea extract, coffee extract, tobacco extract, and red wine staining agent, respectively. The mixture was thoroughly mixed to ensure complete staining of the hydroxyapatite, and excess staining agent was removed. The stained hydroxyapatite was then treated with the test product, and the tooth powder solution was thoroughly removed to obtain stained hydroxyapatite treated with the sample solution. The stained hydroxyapatite was then thoroughly mixed with hydrochloric acid solution for elution and separation, yielding the hydrochloric acid eluent. The ascorbic acid (AS) value of the hydrochloric acid eluent was measured using a spectrophotometer. The AS value was calculated by averaging multiple measurements.

[0087] Hydroxyapatite was rinsed and then added to hydrochloric acid solution. The supernatant was then measured with a spectrophotometer to obtain AH.

[0088] The method for calculating stain removal power is as follows: Where E represents the stain-removing power of the test sample, and AL represents the absorbance after hydroxyapatite staining. The absorbance values ​​are those after hydroxyapatite staining and sample decolorization, while AH represents the absorbance value of the negative control.

[0089] The test results obtained using the above testing method are shown in Table 7.

[0090] Table 7

[0091]

[0092]

[0093] Considering the difference in atomic weights of strontium / potassium and sodium in the samples and controls, resulting in a difference in the amount of polyaspartic acid at the same mass concentration, the stain removal power of the samples and controls listed in Table 7 is basically the same for the four types of stains.

[0094] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A polyaspartic strontium / potassium compound, characterized in that, The preparation steps of the polyaspartic strontium / potassium are as follows: Add 1.08 L of deionized water to a beaker, then add 27.6 g of Sr(OH)2; stir thoroughly until the Sr(OH)2 is completely dissolved, then add 101.7 g of KOH and stir to mix evenly at 20-30 °C; then add 180 g of polysuccinimide with a number average molecular weight of 20 kDa to the resulting mixed solution, and react at 20-30 °C for 2 h with stirring, then filter to remove insoluble matter, and obtain a brownish-yellow aqueous solution; After adjusting the pH of the brownish-yellow aqueous solution to 8.01 with 1 mol / L hydrochloric acid aqueous solution, the solution was ultrafiltered through a filter membrane with a molecular weight cutoff of 3 kDa and the concentrate was collected to obtain a polyaspartic acid strontium / potassium aqueous solution. The polyaspartic acid strontium / potassium aqueous solution was then freeze-dried to obtain polyaspartic acid strontium / potassium.

2. The use of the polyaspartic strontium / potassium polyaspartate as described in claim 1 in the preparation of whitening and anti-sensitivity toothpaste.

3. A whitening and anti-sensitivity toothpaste, characterized in that, The anti-allergy and whitening functional ingredients include the polyaspartic acid strontium / potassium as described in claim 1.

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