Stable slow-release urea peroxide tooth whitening agent composition and preparation method thereof
By using a combination of anhydrous whitening gel and water-based catalyst in teeth whitening products, and utilizing propylene glycol and copolymer thickeners, combined with inorganic salts and alkaline catalysts, a stable sustained-release urea peroxide teeth whitening agent is formed. This solves the problems of unstable thickeners and unstable release of urea peroxide in existing technologies, achieving significant whitening effects and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HAOBAI (ZHEJIANG) MEDICAL EQUIP CO LTD
- Filing Date
- 2026-04-14
- Publication Date
- 2026-05-12
AI Technical Summary
In existing teeth whitening products, conventional thickeners cannot stably form gels in highly alkaline and saline environments of two-component catalyst components, causing the products to easily liquefy or separate during use, affecting the whitening effect, and the release of urea peroxide active ingredients is unstable.
The whitening gel uses anhydrous propylene glycol as the matrix carrier and an aqueous gel as the catalyst. By adjusting the pH value to 7-10, the active ingredient urea peroxide is slowly released under the action of saliva in the mouth after mixing. Hydroxyethyl acrylate/sodium acryloyl dimethyl taurate copolymer is used as a thickener, combined with inorganic salts such as potassium nitrate and sodium fluoride and alkaline catalysts to form a stable slow-release urea peroxide teeth whitening agent.
It significantly improves teeth whitening effect by slowly releasing the active ingredient urea peroxide, enhancing product stability and user experience, and avoiding the instability issues of conventional thickeners.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of teeth whitening compositions, and more particularly to a stable sustained-release urea peroxide teeth whitening agent composition and its preparation method. Background Technology
[0002] Teeth whitening methods mainly include chemical bleaching with medications, cover-up whitening, and professional teeth cleaning and air polishing to restore the natural color of teeth. With the increasing development of cosmetic dentistry, chemical bleaching methods containing peroxides are becoming more and more popular. This method uses the redox chemical reaction of peroxides to break down large organic staining molecules on the tooth surface into smaller molecules, thus lightening the color and fading surface and deep-seated pigments to achieve teeth whitening. The most commonly used effective chemical components for teeth whitening are hydrogen peroxide or urea peroxide. Urea peroxide is an adduct formed by hydrogen bonds between hydrogen peroxide and urea, which dissociates into free urea peroxide and urea in aqueous solution. Teeth whitening agents containing urea peroxide are often used for at-home teeth whitening, meaning patients take the product home and use it themselves under the supervision and guidance of a dentist. Typically, it is used for 2-8 hours daily for about two weeks. Each time, the patient squeezes the product into a custom-made tray for teeth whitening.
[0003] Commercially available at-home teeth whitening products containing urea peroxide typically fall into two categories: single-component and two-component. Two-component products, in addition to the single-component formula, include a catalyst component; one end contains a whitening gel component with urea peroxide, and the other end contains a catalyst component with activating ingredients. For example, patent number 202311236889.9, entitled "A Teeth Whitening Composition Based on Two-Component Solid Particles and Its Preparation Method and Application," includes inert polymer solid particles containing whitening active ingredients and inert polymer solid particles containing a catalyst. Mixing the two solid particles yields the teeth whitening composition based on two-component solid particles. However, this mixture requires strict storage conditions and exhibits low stability.
[0004] For example, patent number 2024116194111.9, entitled "Whitening Toothpaste and its Preparation Method, Method for Whitening Teeth", states that the first paste includes a peroxide and a first carrier, and the second paste includes a low-valence metal salt and a second carrier. After the first paste and the second paste come into contact, a Fenton-like reaction occurs to generate free hydroxyl groups. The free hydroxyl groups act on the teeth to achieve a whitening effect.
[0005] On the other hand, when using whitening products, in order to activate the whitening ingredient urea peroxide, the pH of the two components is usually adjusted to 7-10 after mixing. However, the whitening gel component is generally acidic due to the properties of peroxide itself, with a pH of about 3-5. The common ratio of the whitening gel and the catalyst is generally 4:1. Thus, the alkalinity of the catalyst component must be high enough (e.g., even after a 10,000-fold dilution, its pH value is still around 10). In such a high alkaline and saline environment, conventional thickeners such as carbomer cannot tolerate it and can only barely form a gel. Furthermore, when the whitening gel and the catalyst are mixed during product use, the highly alkaline and saline aqueous gel of the catalyst encounters the anhydrous or slightly aquatic urea peroxide whitening gel, and the carbomer gel immediately liquefies upon contact and becomes unusable. Other common thickeners are also less than ideal and have various problems. For example, silica as a thickener has poor colloidal form, is prone to coarsening and separation during storage, and the released water is prone to leakage, affecting its use. In addition, silica itself is weakly acidic and will undergo an acid-base neutralization reaction with alkaline catalytic components such as sodium hydroxide, resulting in poor composition and affecting product performance. Nonionic surfactants such as poloxamer thickeners produce gels with poor thixotropy, poor leveling properties, and are difficult to spread, affecting their use. Summary of the Invention
[0006] Based on this, the purpose of this invention is to propose a stable sustained-release urea peroxide teeth whitening agent composition and its preparation method. The anhydrous whitening gel component uses propylene glycol as the matrix carrier and an aqueous gel as the catalyst. When using, the two are mixed in a 4:1 ratio, and the pH value of the mixture is 7-10. The mixed product is slowly dissolved by the moisture in oral saliva, continuously releasing the active ingredient urea peroxide, which significantly improves the whitening effect of the product.
[0007] To achieve the above objectives, the present invention provides the following technical solution: a stable sustained-release urea peroxide teeth whitening agent composition, comprising whitening gel and catalyst; Whitening gel, including urea peroxide micron powder, thickener, fragrance and propylene glycol; Catalysts include inorganic salts, thickeners, alkaline catalysts, flavorings, and water.
[0008] Preferably, the whitening gel contains the following components by weight percentage: 10-50% urea peroxide micron powder, 2-6% thickener, 0.05-0.5% fragrance, and the balance being propylene glycol.
[0009] Preferably, the catalyst comprises the following components by mass percentage: 2-27% inorganic salt, 6-8% thickener, 0.2-6.0% alkaline catalyst, 0.05-0.5% fragrance, and the balance being water.
[0010] Preferably, the thickener is a copolymer of hydroxyethyl acrylate and sodium acryloyldimethyl taurate.
[0011] Preferably, the inorganic salt includes one or more of potassium nitrate and sodium fluoride.
[0012] Preferably, the alkaline catalyst includes one of sodium hydroxide, potassium hydroxide, or a strong organic base; the pH value of the mixture of whitening gel and catalyst is 7-10.
[0013] Preferably, the whitening gel and the catalyst are mixed in a volume ratio of 4:1.
[0014] A method for preparing a stable sustained-release urea peroxide teeth whitening agent composition, the preparation method is as follows: S1: Preparation of whitening gel: Add hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer and fragrance to propylene glycol, stir at 1000-2000 rpm for 5 minutes, let stand for 2-4 hours, then add urea peroxide micro powder, stir at 1000-2000 rpm for 10 minutes to disperse it evenly, and finally degas under vacuum to obtain whitening gel; S2: Preparation of the catalyst: Potassium nitrate and sodium fluoride were dissolved in water by stirring. Then, hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer was added and stirred at 1000-2000 rpm for 5 minutes. After standing for 2-4 hours, fragrance and sodium hydroxide solution were added and stirred at 1000-2000 rpm for 10 minutes. Finally, the mixture was degassed under vacuum to obtain the catalyst.
[0015] The preparation method of urea peroxide micro powder is as follows: 1) Add a 35% hydrogen peroxide solution and urea to a jacketed double-layer stirred tank; the stirred tank has two sets of motors: a frame-type stirring motor and a high-speed shear dispersion motor; the weight ratio of hydrogen peroxide solution to urea is 2:1; the double-layer stirred tank has a frame-type stirring motor and a high-speed shear dispersion motor. 2) Control the temperature inside the double-layer stirred tank at 20-30℃, turn on the frame-type stirring motor, and stir the reaction at 50-90 rpm for 30-60 minutes. 3) Then control the temperature inside the double-layer stirred tank at 0℃ to -5℃, turn on the frame stirring motor and the high-speed shear dispersion motor, the stirring paddle at 50-90 rpm and the dispersion disc at 1000-1500 rpm, and continue to stir the mixture. During the process, gradually add an appropriate amount of cyclohexane to stimulate the crystallization of urea peroxide to precipitate fine particles. 4) Filter out the precipitated urea peroxide; 5) Dry at room temperature or under reduced pressure to obtain urea peroxide powder; 6) Pass the urea peroxide powder through a 200-mesh nylon sieve to obtain urea peroxide micro powder.
[0016] This invention employs a two-component structure, consisting of a whitening gel and a catalyst. Urea peroxide micropowder is prepared using a non-mechanical pulverization method and then uniformly dispersed in an anhydrous whitening gel component in a partially insoluble form, exhibiting excellent storage stability without the addition of any peroxide stabilizers. The anhydrous whitening gel component uses propylene glycol as a matrix carrier. Due to the presence of a thickener, the solubility of urea peroxide in the propylene glycol matrix gel at room temperature is low; therefore, the majority of the urea peroxide dispersed in the anhydrous whitening gel component exists in an insoluble form. The catalyst component is an aqueous gel, with added potassium nitrate, sodium fluoride, and other desensitizing inorganic salts, as well as a strong alkaline catalyst (e.g., sodium hydroxide or potassium hydroxide).
[0017] The whitening gel component of this composition is a partially dissolved dispersion system of urea peroxide micropowder, which has a good sustained-release effect of urea peroxide. During the 2-8 hours of use by the patient, the gel squeezed into the dental tray is slowly dissolved by the moisture in the patient's saliva during the wearing process, continuously releasing the active ingredient of urea peroxide, which significantly improves the whitening effect of the product. Detailed Implementation
[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. The following embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In the following embodiments, the percentages in the present invention are mass percentages.
[0019] Example 1: A stable sustained-release urea peroxide teeth whitening composition, comprising a whitening gel and a catalyst; the whitening gel comprises 30% urea peroxide micron powder, 4% hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer, 0.1% fragrance, and 65.9% propylene glycol; the catalyst comprises 20% potassium nitrate, 1.5% sodium fluoride, 6% hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer, 4% sodium hydroxide solution, 0.1% fragrance, and 68.4% water, wherein the concentration of the sodium hydroxide solution is 30%.
[0020] When using, mix the whitening gel and catalyst at a volume ratio of 4:1; the pH value of the mixed product is 8.67.
[0021] Example 2: A stable sustained-release urea peroxide teeth whitening composition, comprising a whitening gel and a catalyst; the whitening gel comprises 50% urea peroxide micron powder, 6% hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer, 0.1% fragrance, and 43.9% propylene glycol; the catalyst comprises 25% potassium nitrate, 2% sodium fluoride, 8% hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer, 19.8% sodium hydroxide solution (equivalent to 5.94% sodium hydroxide), 0.1% fragrance, and 45.1% water, wherein the concentration of the sodium hydroxide solution is 30%.
[0022] When using, the whitening gel and catalyst are mixed in a volume ratio of 4:1; the pH value of the mixed product is 9.93.
[0023] The preparation methods for Examples 1 and 2 are the same, and the steps are as follows: A method for preparing a stable sustained-release urea peroxide teeth whitening agent composition, the preparation method is as follows: S1: Preparation of whitening gel: Add hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer and fragrance to propylene glycol, stir at 1000-2000 rpm for 5 minutes, let stand for 2-4 hours, then add urea peroxide micro powder, stir at 1000-2000 rpm for 10 minutes to make the urea peroxide micro powder uniformly dispersed, and degas under vacuum to obtain whitening gel; S2: Preparation of the catalyst: Potassium nitrate and sodium fluoride were dissolved in water by stirring. Then, hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer was added and stirred at 1000-2000 rpm for 5 minutes. The mixture was allowed to stand for 2-4 hours. Then, fragrance and sodium hydroxide were added and stirred at 1000-2000 rpm for 10 minutes. The mixture was then degassed under vacuum to obtain the catalyst.
[0024] The preparation method of urea peroxide micro powder is as follows: 1) Add a 35% hydrogen peroxide solution and urea to a jacketed double-layer stirred tank; the stirred tank has two sets of motors: a frame-type stirring motor and a high-speed shear dispersion motor; wherein, the weight ratio of the hydrogen peroxide solution to urea is 2:1; the double-layer stirred tank has a frame-type stirring motor and a high-speed shear dispersion motor. 2) Control the temperature inside the double-layer stirred tank at 20-30℃, turn on the frame-type stirring motor, and stir the reaction at 50-90 rpm for 30-60 minutes. 3) Then control the temperature inside the double-layer stirred tank at 0℃ to -5℃, turn on the frame stirring motor and the high-speed shear dispersion motor, the stirring paddle at 50-90 rpm and the dispersion disc at 1000-1500 rpm, and continue to stir the mixture. During the process, gradually add an appropriate amount of cyclohexane to stimulate the crystallization of urea peroxide to precipitate fine particles. 4) Filter out the precipitated urea peroxide; 5) Dry at room temperature or under reduced pressure to obtain urea peroxide powder; 6) Pass the urea peroxide powder through a 200-mesh nylon sieve to obtain urea peroxide micro powder. Comparative Example 1: The whitening gel comprised 30% urea peroxide micron powder, 4% hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer, 0.1% fragrance, and 65.9% water; the catalyst comprised 20% potassium nitrate, 1.5% sodium fluoride, 6% hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer, 4% sodium hydroxide solution, 0.1% fragrance, and 68.4% water, with the sodium hydroxide solution concentration being 30%. The preparation method for Comparative Experiment 1 was the same as that for Example 1.
[0025] Product testing involved filling whitening gel and catalyst separately into dual-tube syringes, with the volume of the whitening gel tube being four times that of the catalyst tube. The filled products were then mixed and extruded using a matching mixing head with an internal spiral static mixing structure before direct testing. The urea peroxide content was determined according to the standard "YY / T 0632-2008 Determination of Peroxide Content in Dental Bleaching Materials". The finished product's urea peroxide content and pH are shown in Table 1. Table 1: Peroxyurea content and pH value of Examples 1, 2 and Comparative Example 1
[0026] Release of urea peroxide The products from Examples 1 and 2, and Comparative Example 1, were mixed and extruded into custom-made dental trays using a matching mixing head for teeth whitening. Samples were taken at various time points during the process to test the urea peroxide content and monitor its loss and release. The monitoring results are shown in Table 2. Table 2: Loss and release of urea peroxide in Examples 1, 2 and Comparative Example 1
[0027] As shown in Table 2, during use, due to the presence of saliva, the urea peroxide dissolved in the product in Comparative Example 1 was lost and released too quickly. After one hour of wearing the whitening tray, the urea peroxide content decreased from the initial 22.18% to 7.32%, indicating that most of it was lost or decomposed and released. The loss or release of urea peroxide in the Examples was significantly slowed down. In Example 1, the content decreased only from the initial 22.76% to 17.98% after one hour, and remained at 11.15% after two hours. In Example 2, the content decreased only from the initial 38.73% to 31.76% after one hour, and remained at 20.14% after two hours. Examples 1 and 2 showed excellent sustained-release effects of urea peroxide; the product gel squeezed into the tray was slowly dissolved by the moisture in the patient's saliva during wear, continuously releasing the active ingredient of urea peroxide.
[0028] Whitening effect evaluation As described above, the product was inserted into the user's custom-made dental tray and worn for 2 hours daily for two consecutive weeks. Before and after two weeks of whitening, the color difference ΔEab* (caused by the increase in ΔL* and the decrease in Δb*) was measured using an electronic colorimeter, referring to the evaluation method in Appendix B of "YY / T 0825-2011 Dentistry - External Teeth Whitening Products," to evaluate the whitening effect of the comparative product. The test results are shown in Table 3. Table 3: Test Results of Examples and Comparative Examples
[0029] The test results show that the whitening effects of Examples 1 and 2 are significantly better than those of the comparative example. Compared with the comparative example, the urea peroxide micro-powder dispersion system of the examples is slowly dissolved by the moisture in the oral saliva during the patient's wearing process, continuously releasing the active ingredient of urea peroxide, which significantly improves the whitening effect.
[0030] Product stability test This experiment investigated the product stability of the comparative and example products by measuring the decrease in urea peroxide content through accelerated aging at 37°C for 4 weeks. The test results are shown in Table 4. Table 4: Product Stability Performance of Examples and Comparative Examples
[0031] The aging test results show that the anhydrous system of the whitening gel component used in the examples exhibits very stable active ingredient urea peroxide, requiring no additional stabilizers. After accelerated aging at 37°C for 4 weeks, the urea peroxide content in Example 1 decreased by only 2.72%, and in Example 2 by only 3.54%. In contrast, the whitening gel component in the comparative examples is an aqueous gel with poor stability; after the same 4-week aging period, most of the urea peroxide had decomposed, with a content decrease of 76.9%.
Claims
1. A stable sustained-release urea peroxide teeth whitening agent composition, characterized in that... Including whitening gel and catalyst; The whitening gel includes urea peroxide micro powder, thickener, fragrance and propylene glycol; The catalyst includes inorganic salts, thickeners, alkaline catalysts, flavorings, and water.
2. The stable sustained-release urea peroxide teeth whitening agent composition according to claim 1, characterized in that, The whitening gel contains the following components by weight percentage: 10-50% urea peroxide micro powder, 2-6% thickener, 0.05-0.5% fragrance, and the balance being propylene glycol.
3. The stable sustained-release urea peroxide teeth whitening agent composition according to claim 1, characterized in that, The catalyst comprises the following components by mass percentage: 2-27% inorganic salt, 6-8% thickener, 0.2-6.0% alkaline catalyst, 0.05-0.5% fragrance, and the balance being water.
4. A stable sustained-release urea peroxide teeth whitening agent composition according to any one of claims 1-3, characterized in that, The thickener is a copolymer of hydroxyethyl acrylate and sodium acryloyl dimethyl taurate.
5. A stable sustained-release urea peroxide teeth whitening agent composition according to claim 1 or 3, characterized in that, The inorganic salts mentioned include one or more of potassium nitrate and sodium fluoride.
6. A stable sustained-release urea peroxide teeth whitening agent composition according to claim 1 or 3, characterized in that, The alkaline catalyst includes one of sodium hydroxide, potassium hydroxide, or a strong organic base; the pH value of the mixture of whitening gel and catalyst is 7-10.
7. The stable sustained-release urea peroxide teeth whitening agent composition according to claim 1, characterized in that, The whitening gel and catalyst are mixed in a volume ratio of 4:
1.
8. A method for preparing a stable sustained-release urea peroxide teeth whitening agent composition, comprising using a stable sustained-release urea peroxide teeth whitening agent composition as described in any one of claims 1-7, characterized in that, The preparation method is as follows: S1: Preparation of whitening gel: Add hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer and fragrance to propylene glycol, stir at 1000-2000 rpm for 2-10 minutes, let stand for 2-4 hours, then add urea peroxide micro powder, stir at 1000-2000 rpm for 2-20 minutes to make it evenly dispersed, and finally degas under vacuum to obtain whitening gel; S2: Preparation of the catalyst: Potassium nitrate and sodium fluoride are dissolved in water by stirring. Then, hydroxyethyl acrylate / sodium acryloyl dimethyl taurate copolymer is added and stirred at 1000-2000 rpm for 2-10 minutes. After standing for 2-4 hours, fragrance and sodium hydroxide are added and stirred at 1000-2000 rpm for 2-20 minutes. Finally, the mixture is degassed under vacuum to obtain the catalyst.
9. The method for preparing a stable sustained-release urea peroxide teeth whitening agent composition according to claim 8, characterized in that, The preparation method of the urea peroxide micro powder is as follows: A 35% hydrogen peroxide solution and urea are added to a jacketed double-layer stirred tank; the weight ratio of the hydrogen peroxide solution to urea is 2:1; the double-layer stirred tank is equipped with a frame-type stirring motor and a high-speed shear dispersion motor. 2) Control the temperature inside the double-layer stirred tank at 20-30℃, turn on the frame-type stirring motor, and stir the reaction at 50-90 rpm for 30-60 minutes. 3) Then control the temperature inside the double-layer stirred tank at 0℃ to -5℃, turn on the frame stirring motor and the high-speed shear dispersion motor, the stirring paddle rotates at 50-90 rpm and the dispersion disc rotates at 1000-1500 rpm, and continue to stir the mixture. During the process, gradually add an appropriate amount of cyclohexane to precipitate urea peroxide. 4) Filter out the precipitated urea peroxide; 5) Dry at room temperature or under reduced pressure to obtain urea peroxide powder; 6) Pass the urea peroxide powder through a 200-mesh nylon sieve to obtain urea peroxide micro powder.