Strontium / potassium polyaspartate as well as preparation method and application thereof

Abstract

The invention discloses strontium / potassium polyaspartate as well as a preparation method and application thereof, and belongs to the technical field of daily chemical products. The strontium / potassium polyaspartate can be prepared by hydrolyzing polysuccinimide in an aqueous solution of strontium hydroxide and potassium hydroxide. The preparation process has the characteristics of mild conditions, simple process, low cost, high efficiency, environmental protection and the like. The strontium / potassium polyaspartate provided by the invention has dual effects of moisturizing, whitening and resisting allergy when being used for whitening and resisting allergy, and compared with the use of sodium polyaspartate, potassium chloride, strontium chloride and strontium / potassium polyaspartate respectively, a large amount of sodium ions and chloride ions are omitted, the ion concentration in the formula is effectively reduced, and the difficulty of the formula is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of daily chemical products, and particularly relates to a polyaspartic acid strontium / potassium, a preparation method thereof and an application thereof. Background Art

[0002] Desensitizing agents are added to anti-allergy toothpaste as anti-allergy active ingredients. Generally, fluorides, silver salts, potassium salts, strontium salts, etc. are selected as desensitizing agents. Among them, strontium ions have an adsorbability to all calcified tissues including dentin. When it enters the dentinal tubules, it reacts with calcium in the dental hard tissues to form calcified strontium apatite and deposits on the wall of the dental tubules, which can seal the open dentinal tubules and thus prevent toothache. Potassium ions act on the nerve endings of the dentinal tubules. By changing the ion gradient, the resting membrane potential of nerve cells can be changed, depolarizing the pulp sensory nerves, thereby interrupting the transmission of pain.

[0003] Polyaspartic acid can not only be used 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 blocking calcium ions at physiological pH values, inhibiting the precipitation of calcium phosphate salts, and ultimately achieving the effects of reducing dental calculus, inhibiting dental plaque, and reducing tooth staining.

[0004] During the production process of anti-allergy toothpaste, abrasives, humectants, thickeners, foaming agents, fragrances, desensitizing agents, water and other additives are formulated and mixed. Generally, potassium and strontium enter the formula in the form of soluble salts such as potassium chloride and strontium chloride, and polyaspartic acid is also added in the form of sodium polyaspartate. Therefore, in order to reflect the anti-allergy and moisturizing effects of toothpaste, there will be a large number of potassium ions, strontium ions, chloride ions, sodium ions and the side-chain carboxylate ions of polyaspartic acid in the formula system, which brings challenges to the selection and dosage of thickeners, the selection and foaming effect of foaming agents, and the whitening and anti-allergy effects of toothpaste.

[0005] Therefore, how to reduce the ionic strength, thereby reducing the toothpaste formulation difficulty and enhancing the whitening and anti-allergy effects is one of the problems that need to be solved for anti-allergy toothpaste. Summary of the Invention

[0006] To solve the above problems, the present invention provides a polyaspartic acid strontium / potassium, a preparation method thereof and an application thereof. 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 has the characteristics of mild process conditions, simple process, low cost, high efficiency and environmental protection. The product polyaspartic acid strontium / potassium has dual effects of moisturizing, whitening and anti-allergy; in addition, compared with separately adding sodium polyaspartate, potassium chloride and strontium chloride, a large number of sodium ions and chloride ions are eliminated, effectively reducing the ionic concentration in the formula and reducing the formulation difficulty.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention: Provide a strontium / potassium polyaspartate, and the structural formula of the strontium / potassium polyaspartate is as follows:

[0009]

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

[0011] The compound of the above structural formula can also be named "strontium / potassium polyaspartate" or "strontium / potassium polyaspartic acid".

[0012] Another technical solution of the present invention: Provide a preparation method of the above strontium / potassium polyaspartate, including the following steps:

[0013] Mix poly(succinimide), strontium hydroxide and potassium hydroxide in water, and obtain the strontium / potassium polyaspartate after hydrolysis reaction;

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

[0015] The strontium content in the strontium / potassium polyaspartate prepared according to the above method is 3.5 to 8.0 wt%, and the potassium content is 18.0 to 25.0 wt%.

[0016] Another name of the raw material "poly(succinimide)" used in the present invention is "polybutanimide".

[0017] Preferably, the number average molecular weight of the poly(succinimide) is 3 to 50 kDa.

[0018] Preferably, the mass ratio of the poly(succinimide) to the water is 1:4 to 10.

[0019] Preferably, the temperature of the hydrolysis reaction is 20 to 60 °C, and the time is 1 to 4 h.

[0020] Preferably, the purification step is further included after the hydrolysis reaction, and the purification step specifically includes: adjusting the pH value of the reaction system to 8.0 to 9.0, then ultrafiltrating and drying to obtain the strontium / potassium polyaspartate.

[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: Provide an application of the above-mentioned strontium / potassium polyaspartate in the preparation of a whitening and anti-allergic toothpaste.

[0023] The fourth technical solution of the present invention: Provide a whitening and anti-allergic toothpaste, and the functional components for anti-allergy and whitening are the above-mentioned strontium / potassium polyaspartate.

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

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

[0026] The strontium / potassium polyaspartate provided by the present invention is used in a whitening and anti-allergic toothpaste, and has the dual effects of moisturizing, whitening and anti-allergy. Compared with separately adding sodium polyaspartate and potassium chloride, strontium chloride, the use of strontium / potassium polyaspartate eliminates a large amount of sodium ions and chloride ions, effectively reduces the ion concentration in the formula, and reduces the formula difficulty. Detailed implementation manners

[0027] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation manners of the present invention. It should be understood that the terms described in the present invention are only used to describe specific implementation manners and are not used to limit the present invention.

[0028] It should be noted that the parts not described in detail in the present invention are all conventional operation means in the art and are not the focus of the present invention.

[0029] In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0030] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention.

[0031] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, that is, they are intended to include but not limited to.

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

[0033] The pH value was measured using a SevenDirect SD20 from Mettler Toledo;

[0034] The strontium content was determined by flame atomic absorption spectrometry in accordance with the light industry standard "QB / T 2968-2021 Method for the determination of strontium content in toothpaste, an oral cleaning and care product";

[0035] The potassium content was determined by flame atomic absorption spectrometry after dilution with reference to the national standard "GB / T 17767.3-2010 Methods for the determination of organic-inorganic compound fertilizers - Part 3: Determination of total potassium content";

[0036] In vitro efficacy evaluation methods such as dentin permeability testing and tooth stain removal ability testing using the conductivity method were used to analyze and compare the tooth hypersensitivity and whitening effects of strontium / potassium polyaspartate.

[0037] In the examples of the present invention, "room temperature" refers to a temperature of 25 ± 5°C.

[0038] Examples 1 to 11

[0039] Preparation of strontium / potassium polyaspartate:

[0040] Accurately measured deionized water was added to a beaker, and then accurately weighed Sr(OH) 2 ; After stirring thoroughly to completely dissolve Sr(OH) 2 accurately weighed KOH was added, and the mixture was stirred and mixed evenly at room temperature; then accurately weighed PSI was added to the resulting mixed solution, and the reaction was carried out at room temperature for 2 h with stirring, and then the insoluble matter was removed by filtration to obtain a brownish-yellow aqueous solution.

[0041] After adjusting the pH value of the above brownish-yellow aqueous solution to 8.0 - 9.0 with 1 mol / L hydrochloric acid aqueous solution, ultrafiltration was carried out through a filter membrane with a molecular weight cut-off of 3 kDa, and the concentrated solution was taken to obtain an aqueous solution of strontium / potassium polyaspartate. The obtained aqueous solution of strontium / potassium polyaspartate was freeze-dried to obtain a pale yellow to yellow powder, which is strontium / potassium polyaspartate.

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

[0043] Table 1

[0044]

[0045] Example 12

[0046] Investigate the stability of the preparation process of strontium / potassium polyaspartate:

[0047] According to the process method of Example 1, five consecutive repeated experiments were carried out, and the product detection results are shown in Table 2.

[0048] Table 2

[0049] 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 strontium / potassium polyaspartate provided by the present invention is relatively stable.

[0051] Example 13

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

[0053] Based on the process method of Example 1, industrial preparation of strontium / potassium polyaspartate was carried out. The specific method is as follows: Add 72.0 L of deionized water to a 100 L reaction tank, and slowly add 1.84 kg of Sr(OH) 2 , after complete dissolution, add 6.87 kg of KOH and stir, dissolve, and mix evenly. After the mixed solution returns to room temperature, slowly add 12 kg of PSI with stirring and continue stirring for 2 h to obtain a brownish-yellow aqueous solution.

[0054] After removing the insoluble matter from the obtained brownish-yellow aqueous solution through a pipeline filter, adjust its pH to 8.0 with 1 mol / L hydrochloric acid aqueous solution, and ultrafilter through a filter membrane with a molecular weight cut-off of 3 kDa. Take the concentrated solution to obtain an aqueous solution of strontium / potassium polyaspartate. Spray-dry the obtained aqueous solution of strontium / potassium polyaspartate to obtain a pale-yellow powder, which is strontium / potassium polyaspartate.

[0055] After testing, the strontium content in the strontium / potassium polyaspartate product prepared in Example 13 is 6.10 wt%, and the potassium content is 21.90 wt%, which is very close to that in Example 1.

[0056] Example 14

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

[0058] Based on the strontium / potassium polyaspartate prepared in Example 1, prepare a whitening and anti-allergic toothpaste according to the formula in Table 3.

[0059] Table 3

[0060]

[0061] Comparative Example 1

[0062] Preparation of whitening toothpaste:

[0063] Using hydrogen peroxide and titanium dioxide as whitening agents, prepare a whitening toothpaste according to the formula in Table 4.

[0064] Table 4

[0065]

[0066]

[0067] Comparative Example 2

[0068] Preparation of anti-allergy toothpaste:

[0069] Using potassium nitrate and hydroxyapatite as anti-sensitivity components, prepare anti-allergy toothpaste according to the formula in Table 5.

[0070] Table 5

[0071]

[0072] Example 15

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

[0074] The greater the degree of opening of dentinal tubules, the stronger the permeability and the higher the tooth sensitivity. The permeability can be evaluated by measuring the conductivity of dentin samples, and then the effect of the test sample on tooth sensitivity can be characterized.

[0075] Experimental method: 1) Use a diamond slicing machine to cut the extracted human third molar into dentin slices with a thickness of 1 - 2 mm, then remove the enamel and cementum, expose the dentin surface, and wash it with distilled water to remove debris for later use. 2) Evenly coat the whitening and anti-sensitivity toothpaste prepared in Example 14 on the surface of the above-treated dentin slices as samples for later use. 3) Fix the above samples in the test device, contact both ends with electrodes, and immerse them in physiological saline at 37°C, and let them stand for 10 min; use a conductivity meter to record the initial conductivity value, and then record the conductivity every 5 min for 30 min.

[0076] Use the dentin slices without coated toothpaste as the blank control, the whitening toothpaste prepared in Comparative Example 1 as the negative control, and the anti-allergy toothpaste prepared in Comparative Example 2 as the positive control. The conductivity measurement results of each group of experiments are shown in Table 6.

[0077] Table 6

[0078]

[0079] As can be seen from Table 6, the whitening and anti-sensitivity toothpaste prepared by the present invention has excellent anti-sensitivity performance, and, compared with the existing commonly used anti-sensitivity components, the strontium / potassium polyaspartate prepared by the present invention has a better tooth anti-allergy effect.

[0080] Example 16

[0081] In vitro Whitening Efficacy Evaluation (Tooth Stain Removal Ability Test)

[0082] By contacting hydroxyapatite with common external tooth staining sources, simulating the staining of tooth matrix, and then through chemical decolorization, bleaching, oxidation, adsorption and other effects in the tooth whitening formula, the absorbance values of the staining source solutions before and after the action of tooth whitening components are measured. The stain removal ability of tooth whitening components on typical pollution sources such as coffee stains, tea stains, red wine stains, and tobacco stains can be calculated.

[0083] Experimental Method:

[0084] 1) Main reagents: Hydroxyapatite (particle size 80μm); Oolong tea (add a little commercially available oolong tea to an appropriate amount of boiling water, soak for 15 minutes and then filter for standby; must be used within 3 hours), coffee (add a little commercially available coffee beans to an appropriate amount of boiling water, soak for 15 minutes and then filter for standby; must be used within 3 hours), tobacco extract (after removing the filter tip and cigarette paper from commercially available cigarettes, add the removed tobacco to an appropriate amount of boiling water, soak for 15 minutes and then filter for standby; must be used within 3 hours), red wine (newly opened commercially available red wine within 3 hours for standby); hydrochloric acid solution (1mol / L); sample solution (0.3wt% aqueous solution of strontium / potassium polyaspartate of Example 1, fully dissolved and filtered with a 0.22μm filter membrane for standby), reference solution (0.3wt% aqueous solution of sodium polyaspartate, fully dissolved and filtered with a 0.22μm filter membrane for standby).

[0085] 2) Test procedure: After rinsing, hydroxyapatite is added to tea extract, coffee, tobacco extract, and red wine staining sources respectively. Mix well to fully stain the hydroxyapatite, remove the excess staining source, and set aside. Mix hydrochloric acid solution with the stained hydroxyapatite thoroughly for elution and separation to obtain hydrochloric acid eluate. Use it as the calibration solution to measure the absorbance of each sample. Measure the hydrochloric acid eluate with a spectrophotometer to get AL, and AL is 0.

[0086] After rinsing, hydroxyapatite is added to tea extract, coffee, tobacco extract, and red wine staining sources respectively. Mix well to fully stain the hydroxyapatite, remove the excess staining source, and set aside. Treat the stained hydroxyapatite with the product to be tested and fully remove the tooth powder solution to obtain the stained hydroxyapatite treated with the sample solution. Mix hydrochloric acid solution with the stained hydroxyapatite thoroughly for elution and separation to obtain hydrochloric acid eluate. Measure the hydrochloric acid eluate with a spectrophotometer to get AS respectively. Take the average value of AS after multiple measurements.

[0087] After rinsing, hydroxyapatite is added to hydrochloric acid solution, and the supernatant is taken and measured with a spectrophotometer to get AH.

[0088] The calculation method of stain removal ability is: Among them, E is the stain removal power of the test sample, AL is the absorbance value after hydroxyapatite staining, is the absorbance value after hydroxyapatite staining and then decolorization by the sample, and AH is the absorbance value of the negative control.

[0089] According to the above test method, the test results obtained are shown in Table 7.

[0090] Table 7

[0091]

[0092]

[0093] Considering the difference in the atomic weights of strontium / potassium elements and sodium elements in the sample and the control, which causes the difference in the amount of substance of polyaspartic acid under the same mass concentration, the stain removal powers of the samples and the control listed in Table 7 for 4 kinds of stains are basically the same.

[0094] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A strontium / potassium polyaspartate, characterized in that: The structural formula of the strontium / potassium polyaspartate is as follows: Among them, x+y+m+n=25~440, and (m+n):(x+y)=1:4~100.

2. A method for preparing strontium / potassium polyaspartate according to claim 1, characterized in that: The following steps are involved: The polysuccinimide, strontium hydroxide and potassium hydroxide are mixed in water, and the polystrontium / potassium aspartate is obtained after hydrolysis reaction; The molar ratio of the succinimide unit in the polysuccinimide, the strontium hydroxide and the potassium hydroxide 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.

3. The method for preparing strontium / potassium polyaspartate according to claim 2, characterized in that: The number average molecular weight of the polysuccinimide is 3 to 50 kDa.

4. The method for preparing strontium / potassium polyaspartate according to claim 2, characterized in that: The mass ratio of the polysuccinimide to the water is 1:4-10.

5. The method for preparing strontium / potassium polyaspartate according to claim 2, characterized in that: The temperature of the hydrolysis reaction is 20-60° C. and the time is 1-4 hours.

6. The method for preparing strontium / potassium polyaspartate according to claim 2, characterized in that: The method further comprises a purification step after the hydrolysis reaction, and the purification step specifically comprises: adjusting the pH value of the reaction system to 8.0-9.0, and then ultrafiltration and drying to obtain the strontium / potassium polyaspartate.

7. Use of the strontium / potassium polyaspartate according to claim 1 in the preparation of whitening and anti-allergic toothpaste.

8. A whitening and anti-allergic toothpaste, characterized in that: The anti-allergic and whitening functional ingredients include the strontium / potassium polyaspartate described in claim 1.

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