Tooth whitening strip and preparation method thereof

Abstract

The invention discloses a tooth whitening strip and a preparation method, and relates to the technical field of oral care. According to the invention, the two key components, namely the adhesive and the desensitization protective agent, of the tooth paste are respectively designed and the synergistic effect of the adhesive and the desensitization protective agent is fully exerted, so that on one hand, the adhesion of the gel layer of the wet tooth paste on the tooth surface and the toughness of the tooth paste are improved, and the gel layer is not easy to fall off or break or remain on the tooth surface; on the other hand, calcium ions, phosphate ions and fluorine ions released by the desensitization protective agent promote generation of acid-resistant fluorapatite and induce remineralization on the enamel surface, and microscopic damage is repaired; and a cross-linked network formed by the adhesive in a gel layer matrix is beneficial to enriching the ions and leading the ions to a to-be-repaired part quickly. The tooth whitening paste can better protect and repair the tooth surface while playing a whitening role, and better oral care experience is provided for a user.

Description

Technical Field

[0001] This invention relates to the field of oral care technology, and in particular to a teeth whitening strip and its preparation method. Background Technology

[0002] The main mechanism of whitening strips is to use oxidants to decolorize extrinsic stains, thus achieving a whitening effect. Currently, whitening strips on the market are made by pressing together active ingredients with a shaping gel. They are categorized into dry and wet strips. Dry strips become sticky when exposed to moisture, adhering strongly to teeth and easily leaving residue, resulting in a poor user experience. Wet strips are already sticky, but their adhesion to teeth is weak, making them prone to falling off. Some whitening strips deform or tear after application, and the gel easily gets stuck in the gaps between teeth, making cleaning difficult and contributing to a poor user experience. Furthermore, the whitening agents in whitening strips often use oxidants such as peroxides. During the process of penetrating tooth enamel, these agents may cause tooth sensitivity or other problems for users with thin or sensitive enamel. Summary of the Invention

[0003] The main objective of this invention is to develop a teeth whitening strip that can effectively improve the teeth whitening effect. The resulting wet strip has strong adhesion and toughness on the tooth surface, making it less prone to falling off or breaking, thus providing users with a better user experience.

[0004] This invention proposes a teeth whitening strip, which includes a gel layer comprising a whitening agent, a moisturizer, a thickener, an adhesive, and a solvent; the whitening agent is selected from at least one of phthalimide peroxyhexanoic acid and sodium phytate; the adhesive comprises a first copolymer obtained from a first monomer, a second monomer, and a third monomer; wherein the first monomer comprises a phosphate ester monomer, the second monomer comprises polyethylene glycol methacrylate, and the third monomer comprises at least one of methyl methacrylate and methyl acrylate.

[0005] In one embodiment, the first copolymer comprises a first monomer, a second monomer, and a third monomer in a weight ratio of (1~2):(6~12):(7~10).

[0006] In one embodiment, the gel layer comprises: a humectant of 30 to 70 parts; a thickener of 5 to 20 parts; a whitening agent of 1 to 20 parts; an adhesive of 3 to 9 parts; and a solvent of 10 to 90 parts.

[0007] In one embodiment, the gel layer comprises a humectant and a binder in a weight ratio of (6-10):1. In another embodiment, the gel layer comprises a humectant and a thickener in a weight ratio of (9-10):3.

[0008] In one embodiment, the gel layer further includes: a sweetener: 0.1 to 1 part; a cooling agent: 0.1 to 2 parts.

[0009] In one embodiment, the humectant includes at least one of glycerin and propylene glycol; and / or, the thickener includes at least one of carbomer, carboxymethyl cellulose, sodium polyacrylate, xanthan gum, ethyl cellulose, and polyvinylpyrrolidone.

[0010] In one specific embodiment, the method for preparing the first copolymer includes the following steps: The second monomer was dissolved in an organic solvent, and then the first and third monomers were added and stirred thoroughly until a homogeneous and transparent premix was formed. Then, an initiator was added dropwise and the temperature was raised to 70°C~80°C. The mixture was stirred and reacted for 4~8 hours under nitrogen protection to obtain a reaction solution. The reaction solution was added dropwise to diethyl ether while stirring to form a precipitate. The lower precipitate was removed to complete the first purification. Multiple purifications were performed, followed by filtration and solvent removal to complete the preparation of the first copolymer.

[0011] In one embodiment, the gel layer further includes 2 to 5 parts by weight of a desensitizing protective agent; the preparation method of the desensitizing protective agent includes the following steps: Disodium hydrogen phosphate solution was added dropwise to Tris buffer solution containing calcium salt, stannous fluoride and dopamine hydrochloride. The solution temperature was maintained at 50℃~55℃ during the reaction. During the dropwise addition, the solution gradually became milky white and turbid, and then the color darkened. After reacting for 12h~20h, the lower layer precipitate was removed, filtered and desoluble, and the preparation of the desensitizing protective agent was completed.

[0012] In one specific embodiment, during the preparation of the desensitizing protective agent, the molar ratio of the calcium salt and the disodium hydrogen phosphate is 1~1.2:1.

[0013] In another specific embodiment, during the preparation of the desensitizing protective agent, the concentration of dopamine hydrochloride is 0.05M~0.1M.

[0014] In one specific embodiment, during the preparation of the desensitizing protective agent, the concentration of stannous fluoride is 0.01M~0.015M.

[0015] In another specific embodiment, during the preparation of the desensitizing protective agent, the concentration of the calcium salt is 0.15M~0.2M.

[0016] This invention also proposes a method for preparing the whitening strips, comprising the following steps: After the raw materials used to prepare the whitening strips are mixed evenly, they are prepared into a gel by vacuum emulsification, and then coated onto a protective film to complete the preparation.

[0017] This invention designs and fully leverages the synergistic effects of the two key components of the whitening strips: the adhesive and the desensitizing protective agent. On one hand, it improves the adhesion of the gel layer of the wet whitening strips to the tooth surface and enhances the strips' toughness, making them less prone to falling off, breaking, or leaving residue on the tooth surface. On the other hand, the calcium, phosphate, and fluoride ions released by the desensitizing protective agent promote the formation of acid-resistant fluorapatite and induce remineralization on the enamel surface, repairing microscopic damage. Furthermore, the cross-linked network formed by the adhesive in the gel matrix facilitates the enrichment of these ions and their rapid attraction to the areas requiring repair. This allows the whitening strips to not only whiten teeth but also better protect and repair the tooth surface, providing users with a superior oral care experience. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0020] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0021] The technical problem this application addresses is that currently available wet whitening strips have poor adhesion to teeth and are prone to falling off. Furthermore, the active ingredients in whitening strips are typically hydrogen peroxide or urea peroxide, with added thickeners and stabilizers, compressed into tablets. During use, because peroxides are somewhat corrosive, both dry and wet whitening strips can cause discomfort to the gums in some individuals. Additionally, some strips are prone to deformation or tearing after application, and gel residue can easily remain in the gaps between teeth, making cleaning difficult and resulting in a poor user experience.

[0022] To address the aforementioned technical problems, this application proposes a teeth whitening strip, comprising a gel layer, the gel layer comprising a whitening agent, a moisturizer, a thickener, an adhesive, and a solvent; the whitening agent is selected from at least one of phthalimide peroxyhexanoic acid and sodium phytate; the adhesive comprises a first copolymer obtained from a first monomer, a second monomer, and a third monomer; wherein the first monomer comprises a phosphate ester monomer, the second monomer comprises polyethylene glycol methacrylate, and the third monomer comprises at least one of methyl methacrylate and methyl acrylate.

[0023] Specifically, this application designs the adhesive, one of the main components of the teeth whitening strip, by copolymerizing phosphate ester monomers, polyethylene glycol methacrylate, and acrylate monomers. The phosphate ester groups can form stable "Ca-OP" coordination bonds with the enamel surface, which helps maintain the viscosity of the whitening strip on the tooth surface. The polyethylene glycol segments in the adhesive give the gel excellent hydrophilicity and spreadability on the tooth surface, making the whitening strip adhere better to the tooth surface without discomfort. Furthermore, the polyethylene glycol segments in the adhesive can form a highly hydrated spatial barrier in the oral environment, preventing dryness during use. The acrylate segments in the adhesive mainly serve as a framework, which helps improve the toughness and cohesive strength of the entire gel layer, ensuring that the gel layer maintains its shape stability in the presence of saliva, preventing excessive swelling, deformation, or tearing, thereby effectively preventing residue and cleaning problems caused by gel squeezing into the gaps between teeth.

[0024] It should also be noted that this application uses phthalimide peroxyhexanoic acid and / or sodium phytate as the whitening agent, which has a relatively mild oxidizing effect. While achieving effective tooth whitening, it significantly reduces the potential risk of damage to tooth enamel and soft tissues. Furthermore, the adhesive used in this application, with its specific ratio, provides an ideal interface for introducing specific desensitizing and restorative agents. The superhydrophilic gel can fully exert its ion-trapping effect, enriching the restorative components released by the desensitizing and restorative agents, such as calcium and fluoride ions, and achieving targeted and sustained delivery to the tooth surface through its network.

[0025] In one embodiment, the first copolymer comprises a first monomer, a second monomer, and a third monomer in a weight ratio of (1~2):(6~12):(7~10).

[0026] Understandably, the second monomer constitutes the main body of the copolymer, which is beneficial for leveraging the adhesive's long-lasting hydrophilicity and steric hindrance effect. The adhesive is dispersed in the gel layer, where the polyethylene glycol segments intercalate with the humectant and thickener to form a hydrated layer that effectively isolates the whitening active ingredients from the gum soft tissue, thereby significantly reducing chemical irritation. Furthermore, the more hydrophilic gel layer is easily rinsed with water or saliva after use, thus avoiding the problem of gel getting stuck between teeth and being difficult to clean. The third monomer is used to provide the necessary rigid support network and needs to be used in the same amount as the second monomer. This ensures that the gel layer has excellent hydrophilicity and comfort while possessing sufficient cohesive strength and morphological stability. During use, it will not swell excessively, deform, or tear due to saliva soaking, thus maintaining the integrity of the patch and ensuring its adhesion durability.

[0027] Furthermore, through the synergistic effect of the different monomers mentioned above, the phosphate groups play an anchoring role, the polyethylene glycol segments greatly improve the interfacial wettability and biocompatibility, and promote the phosphate groups to adhere more tightly and evenly to the tooth surface, while the rigid network of acrylate monomers prevents the polyethylene glycol segments from collapsing due to overhydration.

[0028] In one embodiment, the gel layer comprises: a humectant of 30 to 70 parts; a thickener of 5 to 20 parts; a whitening agent of 1 to 20 parts; an adhesive of 3 to 9 parts; and a solvent of 10 to 90 parts.

[0029] It's important to note that the high proportion of humectants provides long-lasting hydration and works synergistically with the hydrophilic segments or groups in the adhesive to form a continuous hydration medium. This not only provides long-lasting hydration but also effectively disperses whitening agents and desensitizing repair agents, allowing the teeth whitening strips to work gently and evenly, avoiding irritation caused by excessively high local concentrations. Simultaneously, a specific amount of thickener works synergistically with the adhesive network to precisely control the rheological properties of the gel: ensuring it remains stable and non-flowing during storage, has suitable spreadability for proper adhesion during application, and resists erosion by saliva in the mouth to maintain its shape.

[0030] In one specific embodiment, the gel layer comprises a humectant and an adhesive in a weight ratio of (6~10):1.

[0031] Specifically, by further optimizing the dosage of humectant and adhesive, the two complement each other. Sufficient humectant can fully swell the polymer chains of the adhesive, enabling the molecular chains to gain sufficient mobility and spread quickly and fully on the tooth surface. If the adhesive content is too low, a complete and firm adhesive network cannot be formed, causing the veneer to fall off easily; if the adhesive content is too high, the excessive polymer may make the gel too viscous or the film too thick, affecting the comfort of application and the release of active ingredients.

[0032] In a preferred embodiment, the gel layer comprises a humectant and an adhesive in a weight ratio of (6~8):1.

[0033] In another specific embodiment, the gel layer comprises a humectant and a thickener in a weight ratio of (9~10):3.

[0034] Specifically, by compounding specific amounts of moisturizers such as glycerin and propylene glycol, as well as thickeners such as carbomer and xanthan gum, the gel layer can lock in free water in the system. On the one hand, this can dilute and buffer the local concentration of whitening active ingredients such as PAP, and on the other hand, it can maintain the soft texture of the gel layer and have good softness, so that users can feel the gel adhering firmly without pulling or discomfort during the application process.

[0035] In one embodiment, the gel layer further includes: a sweetener: 0.1 to 1 part; a cooling agent: 0.1 to 2 parts. Specifically, the sweetener may be one or more of commonly used sweeteners in the industry, such as sucralose, xylitol, and sodium saccharin; the cooling agent may be one or more of commonly used cooling agents in the industry, such as menthol.

[0036] In one embodiment, the moisturizer includes at least one of glycerin and propylene glycol.

[0037] In one embodiment, the thickener includes at least one of carbomer, carboxymethyl cellulose, sodium polyacrylate, xanthan gum, ethyl cellulose, and polyvinylpyrrolidone.

[0038] In one specific embodiment, the method for preparing the first copolymer includes the following steps: The second monomer was dissolved in an organic solvent, and then the first and third monomers were added and stirred thoroughly to form a homogeneous and transparent premix. Then, an initiator was added dropwise and the temperature was raised to 70°C~80°C. The mixture was stirred and reacted for 4~8 hours under nitrogen protection to obtain a reaction solution. The reaction solution was added dropwise to diethyl ether while stirring to form a precipitate. The lower precipitate was removed to complete the first purification. Multiple purifications were performed, followed by washing and drying to complete the preparation of the first copolymer.

[0039] It should be noted that, due to the high viscosity of the second monomer, polyethylene glycol methacrylate, its complete dissolution is prioritized. This ensures that the polyethylene glycol segments, serving as the hydrophilic lubricant, are uniformly dispersed in the solvent from the outset of the reaction. This allows for homogeneous copolymerization at the molecular level with the other two monomers during subsequent polymerization, preventing component segregation or polyethylene glycol-enriched phases. Furthermore, the copolymerization temperature is limited to 70°C–80°C to prevent excessively vigorous reactions that could lead to branching or crosslinking side reactions, resulting in an overly broad molecular weight distribution in the first copolymer. By employing the above technical solution, the first copolymer can both dissolve in the formulation system to form a stable gel and possess sufficient chain length to construct a strong adhesive network and physical entanglement.

[0040] It should also be noted that the above purification process is performed at least three times, using ether to extract unreacted monomers, oligomers, and initiator decomposition fragments, so that the adhesive does not contain migratable irritating small molecules, thereby preventing the risk of gum discomfort caused by raw material impurities.

[0041] In another specific embodiment, the gel layer further includes 2 to 5 parts by weight of a desensitizing protective agent; the preparation method of the desensitizing protective agent includes the following steps: Disodium hydrogen phosphate solution was added dropwise to Tris buffer solution containing calcium salt, stannous fluoride and dopamine hydrochloride. The solution temperature was maintained at 50℃~55℃ during the reaction. During the dropwise addition, the solution gradually became milky white and turbid, and then the color darkened. After reacting for 12h~20h, the lower layer precipitate was removed, filtered and desoluble, and the preparation of the desensitizing protective agent was completed.

[0042] Specifically, during the preparation of the desensitizing protective agent, calcium ions and phosphate ions co-precipitate to form amorphous calcium phosphate, and dopamine is oxidized and polymerized on the surface of amorphous calcium phosphate to form a polydopamine shell. At the same time, tin ions and fluorine ions provided by stannous fluoride are in situ doped into the amorphous calcium phosphate matrix. The reaction over a long period of time allows the amorphous calcium phosphate to grow fully, eventually forming nanoscale amorphous calcium phosphate particles with a polydopamine shell on the surface.

[0043] It should also be noted that adding the desensitizing protective agent to the gel layer at a dosage of 2 to 5 parts by weight allows it to form strong hydrogen bonds and electrostatic interactions with the phosphate ester and carboxyl groups of the adhesive in the gel layer. This makes the filler particles act as reinforcing cross-linking points in the polymer network, rather than inert fillers, thereby improving overall adhesion and giving the gel better tear resistance. In the application of this application, during use, the amorphous calcium phosphate in the desensitizing protective agent decomposes to release calcium and phosphate ions. Simultaneously, under the action of fluoride ions, it promotes the formation of acid-resistant fluorapatite. Furthermore, calcium and phosphate ions can induce remineralization on the enamel surface, repairing microscopic damage. The cross-linking network formed by the adhesive in the gel layer matrix helps to enrich these ions and quickly direct them to the area to be repaired, thus helping to alleviate the user's tooth sensitivity.

[0044] By adopting the above technical solution, through the synergistic effect of desensitizing agents, adhesives, and other materials in the gel layer, whitening strips can not only whiten teeth but also better protect and repair the tooth surface, alleviate users' tooth sensitivity problems, and provide users with a better oral care experience.

[0045] In a preferred embodiment, the particle size of the desensitizing agent is 10nm~100nm. It is understood that whitening strips with a desensitizing agent of the above particle size have good softness, providing users with good comfort during use, without feeling any foreign objects or hard particles pressing on the tooth surface.

[0046] In one specific embodiment, during the preparation of the desensitizing protective agent, the molar ratio of the calcium salt and the disodium hydrogen phosphate is 1~1.2:1.

[0047] In one specific embodiment, during the preparation of the desensitizing protective agent, the weight ratio of the dopamine hydrochloride, the stannous fluoride, and the calcium salt is 4~10:0.3~0.7:5~6.5.

[0048] In another specific embodiment, during the preparation of the desensitizing protective agent, the concentration of the dopamine hydrochloride is 0.05M~0.1M; and / or, the concentration of the stannous fluoride is 0.01M~0.015M; and / or, the concentration of the calcium salt is 0.15M~0.2M.

[0049] In a more specific embodiment, during the preparation of the desensitizing protective agent, the concentration of dopamine hydrochloride is 0.05M~0.1M, the concentration of stannous fluoride is 0.01M~0.015M, and the concentration of calcium salt is 0.15M~0.2M.

[0050] This invention also proposes a method for preparing the whitening strips, comprising the following steps: After the raw materials used to prepare the whitening strips are mixed evenly, they are prepared into a gel by vacuum emulsification, and then coated onto a protective film to complete the preparation.

[0051] Understandably, the vacuum emulsification method ensures that the active ingredients and nanofillers are evenly dispersed in the gel, while also removing air bubbles introduced during stirring to prevent voids from forming in the gel layer during application.

[0052] The present invention will be further illustrated below through specific embodiments: All raw materials used in the embodiments of this invention are commercially available, and this invention does not impose any restrictions on the source of raw materials.

[0053] Example 1 The teeth whitening strips in Example 1 comprise the following raw materials in parts by weight: Glycerin: 54 parts by weight; Carbomer 940: 6 parts by weight; Phthalimide peroxyhexanoic acid: 8 parts by weight; Sodium phytate: 2 parts by weight; First copolymer: 6 parts by weight; Desensitizing protectant: 3 parts by weight; Water: 20 parts by weight.

[0054] The raw materials for the first copolymer in Example 1 include methacryloyloxyethyl phosphate, polyethylene glycol methacrylate, and methyl methacrylate in a weight ratio of 1:6:7.

[0055] The preparation method of the first copolymer includes the following steps: 30g of polyethylene glycol methacrylate was dissolved in 100mL of an alcohol-water solution (alcohol:water volume ratio 4:1). Then, 5g of methacryloyloxyethyl phosphate and 35g of methyl methacrylate were added, and the mixture was stirred thoroughly until a homogeneous and transparent premix was formed. Next, 0.5g of azobisisobutyronitrile (AIBN) was added dropwise, and the temperature was raised to 70℃~80℃. The mixture was stirred under nitrogen protection for 6 hours to obtain a reaction solution. The reaction solution was added dropwise to 500mL of ice-cold diethyl ether while stirring, resulting in a precipitate. The lower precipitate was collected, redissolved in 50mL of acetone, and then added dropwise to diethyl ether again to precipitate. This purification process was repeated three times. The mixture was then washed and dried at 40℃ to complete the preparation of the first copolymer.

[0056] The preparation method of the desensitizing protective agent in Example 1 includes the following steps: Prepare 200 mL of Tris-HCl buffer solution with a concentration of 0.1 M and a pH of approximately 8.5. Dissolve 5.94 g of dopamine hydrochloride, 0.39 g of stannous fluoride, and 5.29 g of calcium chloride dihydrate in the buffer solution to obtain solution A; dissolve 5.13 g of disodium hydrogen phosphate in 50 mL of deionized water to obtain solution B. Using a constant pressure dropping funnel, solution B is slowly added dropwise to solution A at a rate of 1 mL / min. During the addition process, the temperature of solution A is maintained at 50℃~55℃, and the reaction is continued at this temperature for 16 hours. After the reaction is completed, the solution is cooled to room temperature, centrifuged at 8000 rpm for 15 minutes, the supernatant is discarded, the precipitate is filtered, dried, and ground to a particle size of no more than 100 nm, thus completing the preparation of the desensitizing protective agent.

[0057] The preparation method of the dental strip in Example 1 includes the following steps: Deionized water, glycerin, and carbomer 940 were added to a vacuum emulsifier and stirred at 500 rpm to fully swell the gel. Then, sodium phytate, desensitizing agent powder, and the first copolymer powder, pre-dissolved in a small amount of water, were added sequentially. The stirring speed was increased to 1500 rpm, and homogenization was carried out for 15 minutes. Finally, phthalimide peroxyhexanoic acid was added under low-speed stirring to avoid generating too many bubbles. The entire system was degassed under a vacuum of -0.095 MPa for 10 minutes to obtain a uniform, dense, bubble-free gel layer. The gel was then coated onto a release film to complete the preparation of the whitening strips.

[0058] Example 2 The teeth whitening strips in Example 2 comprise the following raw materials in parts by weight: Glycerin: 40 parts by weight; Propylene glycol: 20 parts by weight; Hydroxyethyl cellulose: 5 parts by weight; Phthalimide peroxyhexanoic acid: 12 parts by weight; Sodium phytate: 2 parts by weight; First copolymer: 8 parts by weight; Desensitizing protectant: 4 parts by weight; Water: 30 parts by weight.

[0059] The raw material ratio and preparation method of the first copolymer in Example 2 are the same as those in Example 1.

[0060] The preparation method of the desensitizing protective agent in Example 2 includes the following steps: Prepare 200 mL of Tris-HCl buffer solution with a concentration of 0.1 M and a pH of approximately 8.5. Dissolve 7.92 g of dopamine hydrochloride, 0.46 g of stannous fluoride, and 5.59 g of calcium chloride dihydrate in the buffer solution to obtain solution A; dissolve 5.91 g of disodium hydrogen phosphate in 50 mL of deionized water to obtain solution B. Using a constant pressure dropping funnel, solution B is slowly added dropwise to solution A at a rate of 1 mL / min. During the addition process, the temperature of solution A is maintained at 50℃~55℃, and the reaction is continued at this temperature for 12 hours. After the reaction is completed, the solution is cooled to room temperature, centrifuged at 8000 rpm for 15 minutes, the supernatant is discarded, the solution is filtered to remove solvent, dried, and then ground to a particle size of no more than 100 nm to complete the preparation of the desensitizing protective agent.

[0061] The preparation method of the dental strip in Example 2 includes the following steps: Deionized water, glycerin, propylene glycol, and hydroxyethyl cellulose were added to a vacuum emulsifier and stirred at 500 rpm to fully swell the gel. Then, sodium phytate, desensitizing agent powder, and the first copolymer powder, pre-dissolved in a small amount of water, were added sequentially. The stirring speed was increased to 1500 rpm, and homogenization was carried out for 20 minutes. Finally, phthalimide peroxyhexanoic acid was added under low-speed stirring to avoid generating excessive bubbles. The entire system was degassed under a vacuum of -0.095 MPa for 10 minutes to obtain a uniform, dense, bubble-free gel layer. The gel was then coated onto a release film to complete the preparation of the whitening strips.

[0062] Comparative Example 1 Comparative Example 1 is based on Example 1, except that the adhesive in the dental strips of Comparative Example 1 is replaced with polyvinylpyrrolidone.

[0063] Performance testing (1) The gel layer of the whitening strips prepared in Examples 1-2 and Comparative Example 1 was subjected to tensile test at room temperature, and the tensile strength at break (MPa) and elongation at break (%) were determined respectively. (2) The gel layer of the whitening strips prepared in Examples 1-2 and Comparative Example 1 was applied to the tooth surface and peeled off after 10 minutes. The presence of any broken or residual material was recorded. 50 samples were tested in each group, and the proportion of samples with broken or residual material (as seen by the naked eye) was recorded. (3) At room temperature, the gel layer of the whitening strips prepared in Examples 1-2 and Comparative Example 1 was applied to the wall of a beaker and then completely immersed in pure water. The dissolution rate of the whitening component in the gel strip was measured at 20 minutes.

[0064] (4) Twelve bovine teeth without caries, fluorosis, or cracks were selected. After ultrasonic vibration, the teeth were rinsed with deionized water and stored in physiological saline. They were then soaked in demineralizing solution for 30 minutes to prepare a tooth enamel damage model. The tooth enamel damage model was then soaked in artificial saliva. Each day, whitening strips prepared in Examples 1-2 and Comparative Example 1 were applied to the enamel surface and soaked in artificial saliva for 1 hour. The strips were then removed, and fresh artificial saliva was used to soak the bovine teeth. The hardness of the enamel was tested using a micro Vickers hardness tester. A Vickers indenter was used, with a test load of 0.9807 N and a holding time of 10 seconds. Five points were measured for each sample, and the average value was taken. The enamel hardness of the samples was recorded after 7 days of treatment with the whitening strips.

[0065] The demineralizing solution was prepared by mixing 2.2 mmol / L calcium chloride, 2.2 mmol / L potassium dihydrogen phosphate, and 50 mmol / L acetic acid, and then adjusting the pH to approximately 4.5. The artificial saliva was prepared by mixing 0.4 g sodium chloride, 0.4 g potassium chloride, 0.795 g calcium chloride, 0.7 g sodium dihydrogen phosphate, 0.005 g sodium sulfide, and 1 g urea, then adding distilled water to a final volume of 1000 mL, and finally adjusting the pH to approximately 7.0.

[0066] The specific results of the above measurements are shown in Tables 1 and 2.

[0067] Table 1

[0068] Table 2

[0069] Analysis of the data in Table 1 shows that the gel layer of the whitening strip in this application has good flexibility and can significantly improve the problem of gel layer breakage or residue during use or peeling; and through the synergistic effect of the adhesive and desensitizing protectant, it can effectively reduce the dilution and dissolution rate of the whitening agent in the gel layer, ensuring the full realization of the whitening effect.

[0070] Analysis of the data in Table 2 shows that the adhesive in the gel layer of this application has a certain promoting effect on the remineralization process of the desensitizing protective agent on the enamel surface, thereby further improving the hardness of the enamel surface and thus playing a better restorative role on the tooth surface.

[0071] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A teeth whitening strip, characterized in that, The whitening strips include a gel layer, which comprises a whitening agent, an adhesive, a moisturizer, a thickener, and a solvent; The whitening agent is selected from at least one of phthalimide peroxyhexanoic acid and sodium phytate; The adhesive comprises a first copolymer derived from a first monomer, a second monomer, and a third monomer; wherein the first monomer comprises a phosphate monomer, the second monomer comprises polyethylene glycol methacrylate, and the third monomer comprises at least one of methyl methacrylate and methyl acrylate.

2. The teeth whitening strips as described in claim 1, characterized in that, The first copolymer comprises a first monomer, a second monomer, and a third monomer in a weight ratio of (1~2):(6~12):(7~10).

3. The teeth whitening strips as described in claim 1, characterized in that, The gel layer comprises, by weight: Moisturizer: 30-70 parts; Thickener: 5-20 parts; Whitening agent: 1-20 parts; Binder: 3-9 parts; Solvent: 10-90 parts.

4. The teeth whitening strip as described in claim 3, characterized in that, The gel layer comprises a humectant and an adhesive in a weight ratio of (6~10):1; And / or, the gel layer comprises a humectant and a thickener in a weight ratio of (9~10):

3.

5. The teeth whitening strip as described in claim 3, characterized in that, The gel layer further includes: Sweetener: 0.1 to 1 part; Cooling agent: 0.1 to 2 parts.

6. The teeth whitening strip as described in claim 5, characterized in that, The moisturizer includes at least one of glycerin and propylene glycol; And / or, the thickener includes at least one of carbomer, carboxymethyl cellulose, sodium polyacrylate, xanthan gum, ethyl cellulose, and polyvinylpyrrolidone.

7. The teeth whitening strip as described in claim 1, characterized in that, The method for preparing the first copolymer includes the following steps: The second monomer was dissolved in an organic solvent, and then the first and third monomers were added and stirred thoroughly until a homogeneous and transparent premix was formed. Then, an initiator was added dropwise and the temperature was raised to 70°C~80°C. The mixture was stirred and reacted for 4~8 hours under nitrogen protection to obtain a reaction solution. The reaction solution was added dropwise to diethyl ether while stirring to form a precipitate. The lower precipitate was removed to complete the first purification. Multiple purifications were performed, followed by filtration and solvent removal to complete the preparation of the first copolymer.

8. The teeth whitening strip as described in claim 3, characterized in that, The gel layer also includes 2 to 5 parts by weight of a desensitizing protective agent; The preparation method of the desensitizing protective agent includes the following steps: Disodium hydrogen phosphate solution was added dropwise to Tris buffer solution containing calcium salt, stannous fluoride and dopamine hydrochloride. The solution temperature was maintained at 50℃~55℃ during the reaction. During the dropwise addition, the solution gradually became milky white and turbid, and then the color darkened. After reacting for 12h~20h, the lower layer precipitate was removed, filtered and desoluble, and the preparation of the desensitizing protective agent was completed.

9. The teeth whitening strip as described in claim 8, characterized in that, In the preparation process of the desensitizing protective agent, the molar ratio of the calcium salt and the disodium hydrogen phosphate is 1~1.2:1; And / or, during the preparation of the desensitizing protective agent, the concentration of dopamine hydrochloride is 0.05M~0.1M; And / or, during the preparation of the desensitizing protective agent, the concentration of stannous fluoride is 0.01M~0.015M; And / or, during the preparation of the desensitizing protective agent, the concentration of the calcium salt is 0.15M~0.2M.

10. A method for preparing teeth whitening strips as described in any one of claims 1 to 9, characterized in that, Includes the following steps: After the raw materials used to prepare the whitening strips are mixed evenly, they are prepared into a gel by vacuum emulsification and then coated onto a release film to complete the preparation of the whitening strips.

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