High-molecular composite false tooth safety paste and preparation method thereof

Abstract

The invention relates to the technical field of oral care, in particular to high-molecular composite false tooth safety paste and a preparation method thereof. The denture safety paste specifically comprises the following components in parts by weight: 10-20 parts of white oil; 20 to 40 parts of Vaseline; 20 to 40 parts of CMC (carboxy methyl cellulose); 20 to 40 parts of PVM-MA (Polyvinyl M-Methacrylate); 0.1 to 1 part of silicon dioxide; 0.1-1 part of 95% ethanol; 0.05 to 1 part of methylparaben; 0.05 to 1 part of menthol; 0.05 to 1 part of peppermint oil; 0.001 to 0.01 part of azo jade red; and 8-12 parts of hydrophobic modified chitosan. The denture fixing paste provided by the invention has high bonding strength, can tolerate high stability requirements under the scenes of excessive chewing, frequent water drinking and the like, can realize long-acting stability for 12-18 hours, and is easy to pick after being used.

Description

Technical Field

[0001] This application relates to the technical field of oral care, and in particular to a polymer composite denture adhesive and its preparation method. Background Technology

[0002] Dentures, as an important medical device for tooth replacement, are widely used by middle-aged and elderly people and patients who have lost teeth due to aging, tooth decay, trauma, etc. Ideal denture fitting requires precise conformation to the oral soft tissues to ensure chewing function, speech expression, and oral hygiene safety. However, in clinical practice, due to individual differences in oral anatomy and factors such as wear and deformation after denture fitting, most dentures cannot perfectly conform to the oral soft tissues, resulting in insufficient retention and poor stability. This not only causes chewing difficulties and reduced eating efficiency but also makes it easy for food debris to become trapped in the gap between the denture and the mucosa. In the warm, moist environment of the mouth, microorganisms thrive, increasing the risk of oral infections and seriously affecting the quality of life and oral health of denture wearers.

[0003] Dental adhesive, as a core auxiliary material for enhancing denture retention and improving wearing stability, has had its practical value validated through long-term clinical practice. According to the ISO 10873 international standard, denture adhesives (i.e., dental adhesive) can be divided into two main categories: Type 1 adhesive (using water-soluble polymers as the core adhesive component, including powder, paste, and sheet types) and Type 2 lining adhesive (non-water-soluble prosthetic denture adhesive). An ideal dental adhesive must meet multiple core requirements: non-toxic and non-irritating to the oral mucosa, excellent biocompatibility, no promotion of microbial growth, odorless and tasteless, easy to use, and quick and thorough removal from the denture tissue-supporting surface.

[0004] In the existing technology, the composition and performance of various denture fixation pastes differ significantly, as detailed below: (1) Type 1 (powder, denture fixation powder): The core component is water-soluble powder such as sodium alginate. When using it, the denture base needs to be moistened first, and then the powder is sprinkled on the surface of the base. It takes effect after biting for a few seconds after wearing. It relies on sodium alginate to absorb water and expand to fill the gap, but the bonding strength is limited, and the powder is easy to fall off and be swallowed during the operation. At the same time, because sodium alginate is extremely water-soluble, it is easily washed away when drinking water or eating during the wearing period, resulting in a rapid decline in the retention effect, which cannot meet the needs of long-term stable wearing.

[0005] (2) Type 1, Category 2 (paste-like, denture fixation paste): The mainstream products use sodium carboxymethyl cellulose and polymethyl vinyl ether-maleic anhydride copolymer (PVM-MA) as core components. Among them, sodium carboxymethyl cellulose has high initial bonding strength and can effectively fill gaps after absorbing water and swelling, but it is highly water-soluble and easily dissolves, resulting in poor fixation durability, and is only suitable for short-term scenarios; PVM-MA has low solubility, long activation time, and longer fixation duration, but it has the defect of insufficient initial bonding strength. Some products in the existing technology have achieved a balance between initial bonding strength and short-term durability, and are easy to remove after 8 hours, gaining market recognition, but still cannot meet the high stability requirements of specific users in scenarios such as excessive chewing and frequent drinking, and it is difficult to achieve long-term stability of 12-18 hours.

[0006] (3) Type 1, Category 3 (thin sheet type, denture bonding pad): uses spunlace nonwoven fabric as a carrier, with sodium alginate sprayed on the surface as an adhesive component. Due to the standardized size of industrial production, it is difficult to adapt to the differences in oral anatomy among different users, and sodium alginate itself has weak bonding strength, resulting in low market acceptance.

[0007] (4) Type 2 (lining type, non-water-soluble prosthesis adhesive): The core component is polyvinyl acetate. Because it is non-water-soluble, the retention time can be up to 24 hours, but there are significant defects: the denture is difficult to remove (especially when it needs to be removed in advance), and the adhesive residue on the denture surface is difficult to completely remove; and the product usually contains a large amount of ethanol, which not only affects the safety of the production process, but also increases the difficulty of approval as a medical device.

[0008] In summary, existing denture retention pastes generally face a core technical dilemma that is difficult to reconcile: short-acting products, while convenient to use and easy to remove after application, have limited bonding strength and cannot withstand the scouring effects of excessive chewing and frequent drinking, resulting in a rapid decline in retention; long-acting products either rely on non-water-soluble ingredients, leading to difficulties in denture removal and residue removal, or pose production safety hazards or compliance deficiencies in medical device approval. Even existing composite retention pastes, which achieve a balance between initial bonding strength and retention within 8 hours, still cannot maintain stable retention under high-load usage scenarios such as excessive chewing and frequent drinking, let alone meet the long-term stability requirements of 12-18 hours.

[0009] In existing technologies, "viscosity" is commonly used to describe the consistency of a product (detected by a rotational viscometer). However, the actual retention ability of denture adhesive is primarily reflected in its adhesive force. Therefore, "bonding strength" can more accurately characterize its retention effect. "Durability" is defined as the duration for which the product maintains effective bonding strength, and it is a key indicator for evaluating the practical performance of denture adhesive.

[0010] Clinical and market feedback shows that denture wearers (especially those who need to eat or socialize for extended periods) have clearly identified the core requirements of Angu paste as "high bonding strength + resistance to chewing / water erosion + 12-18 hours of long-lasting stability + easy removal after use".

[0011] Therefore, developing a polymer composite denture adhesive that can meet the above requirements has become an urgent direction to break through the existing technological bottlenecks and solve the practical problems of denture wearers. Summary of the Invention

[0012] This application provides a polymer composite denture adhesive and its preparation method. The denture adhesive provided by this application has high bonding strength, can withstand the high stability requirements of scenarios such as excessive chewing and frequent drinking, and can achieve long-term stability for 12-18 hours, and is easy to remove after use.

[0013] In the first aspect, this application provides a polymer composite denture fixation paste, which adopts the following technical solution: A polymeric composite denture adhesive, comprising the following components in parts by weight: 10-20 parts white oil; 20-40 parts petrolatum; 20-40 parts CMC (sodium carboxymethyl cellulose); 20-40 parts PVM-MA (calcium sodium salt of methyl vinyl ether-maleic anhydride copolymer); 0.1-1 part silica; 0.1-1 part 95% ethanol; 0.05-1 part methylparaben; 0.05-1 part menthol; 0.05-1 part peppermint oil; 0.001-0.01 part azorubicin; and 8-12 parts hydrophobically modified chitosan (HM-CS).

[0014] In this application, white oil and petrolatum are commonly used oily bases in the pharmaceutical / daily chemical fields. CMC and PVM-MA are classic core adhesive components of type 1 Class 2 paste denture adhesive in ISO 10873 standard. Silica, 95% ethanol, methylparaben, menthol, peppermint oil, and azorubin are also commonly used rheology modifiers, solvents, preservatives, fragrances, and colorants in oral care products. Each component in the formula has a clear role and works synergistically: white oil and petrolatum work together to regulate the consistency, spreadability, and formability of the paste, while slowing down the dissolution rate of water-soluble adhesive components to prolong the fixation time; CMC absorbs water and swells rapidly upon contact with saliva, filling the gap between the denture and the mucosa and providing excellent initial bonding strength; PVM-MA, with its low solubility, is slowly activated to form a stable adhesive layer for long-term stability. The combination of the two precisely matches the core requirements of "initial fixation + long-term stability"; silica improves the thixotropy and storage stability of the paste, preventing stratification and sedimentation; 95% ethanol helps to evenly disperse the fat-soluble components; methylparaben inhibits microbial growth to extend shelf life; menthol and peppermint oil provide a refreshing taste and mask odors, improving wearing comfort; azorubine gives the product a specific color, enhancing its visual recognition, ultimately forming a practical formula that balances adhesive performance, user experience, and storage stability.

[0015] The addition of hydrophobically modified chitosan in this application can specifically address the shortcomings of the basic solution, such as "insufficient bonding strength and weak resistance to scene interference".

[0016] The core function of hydrophobically modified chitosan is "basic reinforcement + hydrophobic protection," based on the interaction between structure and components: the hydrophobic segments of hydrophobically modified chitosan are compatible with the oil phase (white oil, petrolatum) of the basic solution and can be uniformly dispersed in the system, avoiding the "adhesion failure caused by water / oil phase stratification" in the basic solution; the amino and hydroxyl groups of chitosan can form hydrogen bonds with the carboxyl groups of CMC and PVM-MA in the basic solution, strengthening the intermolecular forces at the bonding interface and improving the initial bonding strength; the hydrophobically modified segments form a dense hydrophobic layer at the bonding interface, reducing the penetration and swelling of artificial saliva, reducing the damage to the bonding interface caused by chewing and drinking, thereby improving the anti-interference stability.

[0017] Optionally, the hydrophobically modified chitosan is 9-11 parts by weight.

[0018] In one specific embodiment, the hydrophobically modified chitosan is in the following weight proportions: 8 parts, 9 parts, 10 parts, 11 parts, and 12 parts.

[0019] In some specific embodiments, the hydrophobically modified chitosan is in the following weight proportions: 8-9 parts, 8-10 parts, 8-11 parts, 9-10 parts, 9-11 parts, 9-12 parts, 10-11 parts, 10-12 parts, and 11-12 parts.

[0020] Optionally, the method for preparing the hydrophobically modified chitosan includes the following steps: (1) Chitosan dissolution: Add chitosan to glacial acetic acid solution and stir at room temperature until completely dissolved to form a uniform, transparent, viscous solution; (2) Schiff base formation: Slowly add octanal or dodecyl ethanol to chitosan solution; maintain system temperature at 42-48℃, stir at 150-200r / min in the dark for 7-11h to form a uniform yellow transparent Schiff base intermediate solution. (3) Reduction reaction: Cool the reaction solution to room temperature naturally, and slowly adjust the pH to 9-10 with NaOH solution; add sodium borohydride in portions, maintaining the pH at 9-10 during the addition process, and stir the reaction at 150-200 r / min for 2.5-3.5 h. (4) Product purification: After the reaction is completed, the pH is slowly adjusted to 6.2-6.8 with HCl solution; the neutralized solution is slowly poured into anhydrous ethanol to precipitate, and the white solid is collected by filtration; the product is washed 2-3 times with anhydrous ethanol and distilled water in sequence, and then dried under vacuum to obtain a white or light yellow powder product.

[0021] Optionally, the denture fixation paste further includes 10-15 parts of amino-modified hydroxypropyl methylcellulose (HPMC-NH2) and 2-5 parts of aldehyde-modified polyethylene glycol diacrylate (PEG-CHO-DA).

[0022] Optionally, the amino-hydroxypropyl methylcellulose is present in parts by weight of 12-14.

[0023] In one specific embodiment, the amino-hydroxypropyl methylcellulose is present in parts by weight of 10, 12, 13, 14, or 15.

[0024] In some specific embodiments, the amino-hydroxypropyl methylcellulose is expressed in parts by weight of 10-12, 10-13, 10-14, 12-13, 12-14, 12-15, 13-14, 13-15, or 14-15.

[0025] Optionally, the aldehyde-based polyethylene glycol diacrylate is present in parts by weight of 3-4 parts.

[0026] In one specific embodiment, the aldehyde-based polyethylene glycol diacrylate is present in parts by weight of 2, 3, 3.5, 4, or 5.

[0027] In some specific embodiments, the aldehyde-based polyethylene glycol diacrylate is present in parts by weight of 2-3 parts, 2-4 parts, 2-5 parts, 3-3.5 parts, 3-4 parts, 3-5 parts, 3.5-4 parts, 3.5-5 parts, or 4-5 parts.

[0028] In this application, the addition of hydrophobically modified chitosan, followed by the addition of amino-modified hydroxypropyl methylcellulose and aldehyde-modified polyethylene glycol diacrylate, can further solve the problem of "insufficient long-term stability" and enhance the overall performance.

[0029] The core function of amino-hydroxypropyl methylcellulose and aldehyde-modified polyethylene glycol diacrylate is "dynamic cross-linking network construction", which forms a synergistic system of "basic reinforcement + dynamic long-term effect" with hydrophobically modified chitosan. The principle is as follows: The amino group (-NH2) of aminated HPMC reacts with the aldehyde group (-CHO) of aldehyde-modified polyethylene glycol diacrylate through a Schiff base reaction (generating a -C=N- dynamic covalent bond), forming a three-dimensional cross-linked network in the system. This network has a certain strength (enhancing adhesion and anti-chewing properties) and can slowly and reversibly dissociate in the oral environment (the strength drops to 50% of the initial value after 12-18 hours, making it easy to remove). The hydrophobic layer constructed by hydrophobically modified chitosan can reduce the hydrolytic damage of the Schiff base dynamic bond by artificial saliva, prolonging the stability time of the cross-linked network, thereby achieving long-term stability of 12-18 hours. The appropriate amount of aminated HPMC and aldehyde-modified polyethylene glycol diacrylate avoids both "long-term failure caused by insufficient cross-linking" and "difficulty in removal caused by excessive cross-linking", ultimately achieving a balance between "long-term stability and convenient removal".

[0030] Optionally, the method for preparing the amino-modified hydroxypropyl methylcellulose includes the following steps: (1) Alkalization treatment: HPMC is added to a mixed solvent of isopropanol and water and stirred at room temperature until completely dissolved; NaOH solution is slowly added dropwise to adjust the pH to 10-12, the temperature is maintained at 25-35℃, and the reaction is stirred for 1-2 hours to form an alkaline cellulose solution; (2) Amination reaction: Dissolve CTA in deionized water and slowly add it dropwise to the alkaline cellulose solution; heat to 65-75℃ and stir at 150-200r / min for 4-6h under nitrogen protection, maintaining pH 10-12; determination of reaction endpoint: take a small amount of sample and test with silver nitrate solution to detect no chloride ion precipitation; (3) Neutralization and purification: After the reaction is completed, cool to room temperature and adjust the pH to 7.0-7.5 with HCl; pour the solution into acetone to precipitate, filter and collect the white solid; wash with acetone and distilled water in sequence, and vacuum dry to obtain a white powder product.

[0031] Optionally, the method for preparing the aldehyde-based polyethylene glycol diacrylate includes the following steps: (1) PEG aldehyde hydration: Dissolve PEG in distilled water and add ethylene glycol as a protective agent; under light-protected conditions, add sodium periodate in portions, control the system temperature at 28-32℃, and stir the reaction at 150-200r / min for 4.5-5.5h. (2) PEG-CHO purification: After the reaction was completed, excess ethylene glycol was added to terminate the reaction; the reaction solution was dialyzed for 40-50 h to completely remove inorganic salts; the dialysate was freeze-dried to obtain a white flocculent PEG-CHO intermediate; (3) Acrylate modification: Dissolve PEG-CHO in anhydrous dichloromethane, add triethylamine, and cool in an ice bath; slowly add acrylic anhydride, maintaining the system temperature ≤10℃ during the addition process, and continue stirring at 150-200r / min for 1.5-2.5h under ice bath conditions; then raise the temperature to room temperature and continue stirring for 14-22h. (4) Product purification: Add sodium bicarbonate solution to the reaction solution, shake and wash, let stand and separate into layers and discard the aqueous phase; dry the organic phase with anhydrous sodium sulfate and filter to remove the desiccant; evaporate the filtrate by rotary evaporation at 35-40℃ and 0.03-0.05MPa; slowly add the concentrated product dropwise to anhydrous diethyl ether while stirring to promote complete precipitation; filter and collect the white precipitate, vacuum dry to obtain a colorless, transparent, viscous product.

[0032] Secondly, this application provides a method for preparing a polymeric composite denture adhesive, employing the following technical solution: A method for preparing a polymeric composite denture adhesive, the method specifically comprising the following steps: (1) Put white oil and petroleum jelly into an emulsifying pot, heat to 60-80℃, and stir continuously at a stirring speed of 100-150r / min for 10-20min until the petroleum jelly is completely melted to form a uniform and continuous oil phase system; (2) Add PVM-MA to the oil phase system and stir at a stirring speed of 150-200 r / min for 50-70 min to make PVM-MA uniformly dispersed in the oil phase; (3) Add CMC, hydrophobically modified chitosan and silica to the system, and continue stirring at a stirring speed of 200-250 r / min for 50-70 min to ensure that CMC, silica and oil phase and PVM-MA are fully integrated; (4) Add methylparaben, peppermint oil, menthol, azorubin and 95% ethanol to the system in sequence, then evacuate to -0.05~-0.1MPa, stir at a stirring speed of 250-300r / min for 1.5-2.5h to ensure that all excipients are thoroughly mixed, and the denture fixation paste is obtained.

[0033] Optionally, the denture fixation paste further includes amino-substituted hydroxypropyl methylcellulose and aldehyde-substituted polyethylene glycol diacrylate.

[0034] Optionally, the timing of adding the amino-modified hydroxypropyl methylcellulose is consistent with the timing of adding CMC.

[0035] Optionally, the aldehyde-modified polyethylene glycol diacrylate is added before the addition of methylparaben.

[0036] In summary, this application includes at least one of the following beneficial technical effects: The denture adhesive provided in this application has high bonding strength, can withstand the high stability requirements of excessive chewing and frequent drinking, and can achieve long-term stability for 12-18 hours. It is also easy to remove after use. Detailed Implementation

[0037] Before describing the embodiments of this application in detail, it should be understood that the terminology used herein is for the purpose of describing a particular embodiment only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term pertains.

[0038] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0039] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0040] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0041] This application provides a polymeric composite denture securing paste. The denture securing paste specifically comprises the following components in parts by weight: 10-20 parts white oil; 20-40 parts petrolatum; 20-40 parts CMC; 20-40 parts PVM-MA; 0.1-1 part silica; 0.1-1 part 95% ethanol; 0.05-1 part methylparaben; 0.05-1 part menthol; 0.05-1 part peppermint oil; 0.001-0.01 part azorubicin; and 8-12 parts hydrophobically modified chitosan.

[0042] Furthermore, the denture fixation paste also includes 10-15 parts of amino-modified hydroxypropyl methylcellulose and 2-5 parts of aldehyde-modified polyethylene glycol diacrylate.

[0043] The preparation method of hydrophobically modified chitosan (HM-CS, grafted C8-C12 alkyl chain) includes the following steps: (1) Chitosan dissolution: Add 45-55g of chitosan (degree of deacetylation ≥90%) to 450-550ml of 10% (mass-volume ratio) glacial acetic acid solution, and stir at 150-200r / min for 1.2-1.8h at room temperature (20-25℃) until completely dissolved to form a uniform and transparent viscous solution.

[0044] (2) Schiff base formation: Dissolve 28-52g (0.23-0.42mol) of octanal or dodecanoal (C8 / C12 alkyl chain selected according to requirements) in 90-110ml of anhydrous ethanol, and slowly add it dropwise to the chitosan solution over 30-60min; maintain the system temperature at 42-48℃, and stir the reaction at 150-200r / min in the dark for 7-11h to form a uniform yellow transparent Schiff base intermediate solution.

[0045] (3) Reduction reaction: Cool the reaction solution to room temperature naturally, and slowly adjust the pH to 9-10 with 0.8-1.2 mol / L NaOH solution; add 15-20 g (0.39-0.53 mol) of sodium borohydride (NaBH4) in 3-5 portions, maintaining the pH at 9-10 during the addition process, and stir the reaction at 150-200 r / min for 2.5-3.5 h.

[0046] (4) Product purification: After the reaction is completed, the pH is slowly adjusted to 6.2-6.8 with 0.8-1.2 mol / L HCl solution; the neutralized solution is slowly poured into 900-1100 ml of anhydrous ethanol, and stirred at 100-150 r / min for 10-15 min to promote complete precipitation. The white solid is collected by filtration; the solid is washed 2-3 times with 300-400 ml of anhydrous ethanol and 2-3 times with 300-400 ml of distilled water, and then vacuum dried at 38-42℃ and 0.02-0.05 MPa for 20-26 h to obtain a white or light yellow powder HM-CS product.

[0047] The preparation method of amino-modified hydroxypropyl methylcellulose (HPMC-NH2) includes the following steps: (1) Alkalization treatment: Add 100g HPMC to 450-550ml of isopropanol / water mixed solvent (volume ratio of 9:1), stir at room temperature for 30-60min until completely dissolved; slowly add 20-40% NaOH solution, adjust pH to 10-12, maintain temperature at 25-35℃, stir reaction for 1-2h to form alkaline cellulose solution for later use.

[0048] (2) Amination reaction: Dissolve 10-30g (0.05-0.15mol) CTA (3-chloro-2-hydroxypropyltrimethylamine hydrochloride) in 40-60ml of deionized water and slowly add it dropwise to the alkaline cellulose solution over 30-60min; raise the temperature to 65-75℃ and stir the reaction at 150-200r / min for 4-6h under nitrogen protection, maintaining the pH at 10-12; the endpoint of the reaction is determined by taking a small amount of sample and testing with silver nitrate solution to detect the absence of chloride ion precipitation.

[0049] (3) Neutralization and purification: After the reaction is completed, cool to room temperature and adjust the pH to 7.0-7.5 with 0.8-1.2 mol / L HCl; pour the solution into 900-1100 ml of acetone to precipitate, filter and collect the white solid; wash with acetone and distilled water 2-3 times in sequence, and dry at 40-50℃ and vacuum degree <0.05MPa for 12-24 h to obtain a white powder product.

[0050] Degree of substitution (DS) control: By adjusting the amount of CTA (10-30g), an amino substitution degree of 0.3-0.8 can be obtained.

[0051] The preparation method of aldehyde-modified polyethylene glycol diacrylate (PEG-CHO-DA) includes the following steps: (1) PEG aldehyde conversion: Dissolve 100g PEG (polyethylene glycol, Mn=2000-6000) in 280-320ml distilled water, add 8-12ml ethylene glycol as a protective agent (to inhibit excessive oxidation of aldehyde groups); under light-protected conditions, add 22-28g (0.10-0.13mol) sodium periodate (NaIO4) in 3-5 portions, control the system temperature at 28-32℃, and stir the reaction at 150-200r / min for 4.5-5.5h.

[0052] (2) PEG-CHO purification: After the reaction is completed, add 5-8 ml of excess ethylene glycol to terminate the reaction (react with the remaining sodium periodate); transfer the reaction solution into a dialysis bag with a molecular weight cutoff of 1000, and dialyze with deionized water for 40-50 h (replace the deionized water every 8-12 h) to completely remove inorganic salts; freeze-dry the dialysate (temperature -40~-30℃, vacuum degree 0.01-0.03MPa) to obtain a white flocculent PEG-CHO intermediate.

[0053] (3) Acrylate modification: Dissolve 45-55g of PEG-CHO in 230-270ml of anhydrous dichloromethane (DCM), add 9-11ml of triethylamine (TEA), and cool in an ice bath to 0-5℃; slowly add 18-22g (0.17-0.22mol) of acrylic anhydride over 30-60min, maintaining the system temperature ≤10℃ during the addition process. After the addition is complete, continue stirring the reaction at 150-200r / min for 1.5-2.5h under ice bath conditions; then remove the ice bath, raise the temperature to room temperature (20-25℃), and continue stirring the reaction for 14-22h.

[0054] (4) Product purification: Add 90-110 ml of 5% (mass-volume ratio) sodium bicarbonate (NaHCO3) solution to the reaction solution, shake and wash 2-3 times, let stand for separation and discard the aqueous phase (containing unreacted acrylic anhydride and TEA·HCl); dry the organic phase with 15-20 g of anhydrous sodium sulfate for 2-4 h, filter to remove the desiccant; concentrate the filtrate to 1 / 3-1 / 2 of the original volume by rotary evaporation at 35-40℃ and 0.03-0.05 MPa; slowly add the concentrated product dropwise to 900-1100 ml of anhydrous diethyl ether while stirring (100-150 r / min) to promote complete precipitation; filter and collect the white precipitate, and vacuum dry at 38-42℃ and 0.02-0.05 MPa for 20-26 h to obtain a colorless, transparent, viscous PEG-CHO-DA product.

[0055] This application also provides a method for preparing a polymeric composite denture adhesive. The preparation method specifically includes the following steps: (1) Raw material pretreatment: Prepare materials and strictly control the moisture content of each raw material. Solid raw materials such as CMC and PVM-MA can be dried in advance (drying at 50-60℃ for 2-4 hours) to avoid residual moisture in subsequent processes from condensing into water droplets at the top of the emulsification pot and falling into the paste to form hard particles.

[0056] (2) Melting and emulsifying white oil and petroleum jelly: Put white oil and petroleum jelly into an emulsifying pot, heat to 60-80℃, and stir continuously at a stirring speed of 100-150r / min for 10-20min until the petroleum jelly is completely melted to form a uniform and continuous oil phase system.

[0057] (3) Heat preservation and dispersion of PVM-MA: PVM-MA is added to the oil phase system and stirred at a stirring speed of 150-200r / min for 50-70min to make PVM-MA uniformly dispersed in the oil phase.

[0058] (4) Insulation and mixing of CMC, hydrophobic modified chitosan and silica: Add CMC and silica to the system and continue stirring at a stirring speed of 200-250r / min for 50-70min to ensure that CMC, silica and oil phase and PVM-MA are fully integrated without clumping or local aggregation.

[0059] (5) Addition of functional excipients and vacuum emulsification: Add methylparaben, peppermint oil, menthol, azorubicin, and 95% ethanol to the system in sequence, then vacuum to -0.05~-0.1MPa, and stir at a stirring speed of 250-300r / min for 1.5-2.5h to ensure that all excipients are thoroughly mixed. At the same time, the humidity around the emulsification pot should be controlled to further prevent moisture condensation and contamination of the paste.

[0060] (6) Cooling: After emulsification is complete, stop heating and let it cool naturally to 40-50℃ to allow the paste to initially solidify to a suitable consistency.

[0061] (7) Filling and post-processing: Maintain the temperature of the paste at 40-50℃, and carry out the processes of filling, capping and sealing in sequence. Then, complete the boxing and coding, and finally package and put it into the warehouse.

[0062] Furthermore, the denture fixation paste also includes amino-modified hydroxypropyl methylcellulose and aldehyde-modified polyethylene glycol diacrylate. The amino-modified hydroxypropyl methylcellulose is added at the same time as the CMC. The aldehyde-modified polyethylene glycol diacrylate is added before the addition of methylparaben.

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0064] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0065] The following provides a more detailed description of this application in conjunction with preparation examples, implementation examples, and test results.

[0066] Preparation Example 1 This preparation example provides a hydrophobically modified chitosan (HM-CS).

[0067] The preparation method of the above-mentioned hydrophobically modified chitosan includes the following steps: (1) Chitosan dissolution: Add 50g of chitosan (degree of deacetylation ≥90%) to 500ml of 10% glacial acetic acid solution and stir at 180r / min for 1.5h at room temperature until completely dissolved to form a uniform and transparent viscous solution.

[0068] (2) Schiff base formation: Dissolve 40g of octanal in 100ml of anhydrous ethanol and slowly add it dropwise to the chitosan solution over 40min; maintain the system temperature at 45℃ and stir at 180r / min in the dark for 9h to form a uniform yellow transparent Schiff base intermediate solution.

[0069] (3) Reduction reaction: Cool the reaction solution to room temperature naturally, and slowly adjust the pH to 9-10 with 1mol / L NaOH solution; add 18g sodium borohydride in 4 portions, maintaining the pH at 9-10 during the addition process, and stir the reaction at 180r / min for 3h.

[0070] (4) Product purification: After the reaction is completed, the pH is slowly adjusted to 6.2-6.8 with 1 mol / L HCl solution; the neutralized solution is slowly poured into 1000 ml of anhydrous ethanol, stirred at 180 r / min for 12 min to promote complete precipitation, and the white solid is collected by filtration; the solid is washed 3 times with 300-400 ml of anhydrous ethanol and 3 times with 300-400 ml of distilled water, and then vacuum dried at 40℃ and 0.03 MPa for 24 h to obtain white or light yellow powdered HM-CS product.

[0071] Preparation Example 2 This preparation example provides an amino-modified hydroxypropyl methylcellulose (HPMC-NH2).

[0072] The above-mentioned method for preparing amino-hydroxypropyl methylcellulose includes the following steps: (1) Alkalization treatment: Add 100g HPMC (hydroxypropyl methylcellulose, viscosity 1000-5000mPa·s) to 500ml isopropanol / water mixed solvent (volume ratio 9:1), stir at room temperature for 40min until completely dissolved; slowly add 20-40% NaOH solution, adjust pH to 10-12, maintain temperature at 30℃, stir reaction for 1.5h to form alkaline cellulose solution for later use.

[0073] (2) Amination reaction: Dissolve 25g CTA in 50ml deionized water and slowly add it dropwise to an alkaline cellulose solution over 30-60min; heat to 70℃ and stir under nitrogen protection for 5h, maintaining pH 10-12 (add NaOH if necessary). Endpoint determination: Take 0.1-1.0g of sample and test with 0.1-0.2mol / L silver nitrate solution. The endpoint is determined when no obvious chloride ion precipitate is formed.

[0074] (3) Neutralization and purification: After the reaction is completed, cool to room temperature (20-25℃), adjust the pH to 7.0-7.5 with 1mol / L HCl; pour the solution into 1000ml acetone, stir for 10min to promote precipitation, filter and collect the white solid; wash 3 times with 300-400ml acetone and 3 times with 300-400ml distilled water, then vacuum dry (40-50℃, vacuum degree <0.05MPa) for 18h to obtain white powdered HPMC-NH2 product.

[0075] Preparation Example 3 This preparation example provides an aldehyde-based polyethylene glycol diacrylate (PEG-CHO-DA).

[0076] The preparation method of the above-mentioned aldehyde-modified polyethylene glycol diacrylate includes the following steps: (1) PEG aldehyde: Dissolve 100g PEG in 300ml distilled water and add 10ml ethylene glycol as a protective agent; under light-protected conditions, add 25g sodium periodate in 4 portions, control the system temperature at 30℃, and stir the reaction at 180r / min for 5h.

[0077] (2) PEG-CHO purification: After the reaction was completed, 6 ml of excess ethylene glycol was added to terminate the reaction; the reaction solution was transferred into a dialysis bag with a molecular weight cutoff of 1000 and dialyzed with deionized water for 45 h (the deionized water was replaced every 9 h) to completely remove inorganic salts; the dialysate was freeze-dried (temperature -35℃, vacuum degree 0.02MPa) to obtain white flocculent PEG-CHO intermediate.

[0078] (3) Acrylate modification: Dissolve 50g PEG-CHO in 250ml anhydrous dichloromethane, add 10ml triethylamine, and cool in an ice bath to 0-5℃; slowly add 20g acrylic anhydride over 40min, maintaining the system temperature ≤10℃ during the addition process, and continue stirring at 180r / min for 2h under ice bath conditions after the addition is complete; then remove the ice bath, raise the temperature to room temperature, and continue stirring for 18h.

[0079] (4) Product purification: Add 100 ml of 5% sodium bicarbonate solution to the reaction solution, shake and wash 3 times, let stand and separate the layers, and discard the aqueous phase; dry the organic phase with 18 g of anhydrous sodium sulfate for 3 h, and filter to remove the desiccant; concentrate the filtrate to 1 / 3-1 / 2 of the original volume by rotary evaporation at 38℃ and 0.034 MPa; slowly add the concentrated product dropwise to 1000 ml of anhydrous diethyl ether while stirring (120 r / min) to promote complete precipitation; filter and collect the white precipitate, and vacuum dry it at 40℃ and 0.04 MPa for 22 h to obtain a colorless, transparent, viscous PEG-CHO-DA product.

[0080] Example 1

[0081] This embodiment provides a polymeric composite denture adhesive. The specific amounts of each component are shown in Table 1. The hydrophobically modified chitosan used was prepared in Preparation Example 1.

[0082] The preparation method of the above-mentioned denture bonding paste specifically includes the following steps: (1) Raw material pretreatment: Prepare materials and strictly control the moisture content of each raw material. Dry solid raw materials such as CMC and PVM-MA in advance (dry at 50-60℃ for 2-4 hours) to prevent residual moisture from condensing into water droplets at the top of the emulsification pot in subsequent processes and falling into the paste to form hard particles.

[0083] (2) Melting and emulsifying white oil and petroleum jelly: Add white oil and petroleum jelly to an emulsifying pot, heat to 70°C, and stir continuously at a stirring speed of 120 r / min for 15 min until the petroleum jelly is completely melted to form a uniform and continuous oil phase system.

[0084] (3) Heat preservation and dispersion of PVM-MA: PVM-MA is added to the oil phase system and stirred at a stirring speed of 180r / min for 60min to keep PVM-MA uniformly dispersed in the oil phase.

[0085] (4) Insulation and mixing of CMC, hydrophobic modified chitosan and silica: Add CMC and silica to the system and continue stirring at a stirring speed of 220r / min for 60min to ensure that CMC, silica and oil phase and PVM-MA are fully integrated without clumping or local aggregation.

[0086] (5) Addition of functional excipients and vacuum emulsification: Add methylparaben, peppermint oil, menthol, azorubicin and 95% ethanol to the system in sequence, then vacuum to -0.08MPa and keep warm and stir at 280r / min for 2h to ensure that all excipients are thoroughly mixed.

[0087] (6) Cooling: After emulsification is complete, stop heating and let it cool naturally to 45°C to allow the paste to initially solidify to a suitable consistency.

[0088] (7) Filling and post-processing: Maintain the temperature of the paste at 45°C, and carry out the filling, capping and sealing processes in sequence. Then, complete the boxing and coding, and finally package and put it into the warehouse.

[0089] Table 1. Dosage of each component in Example 1

[0090] Table 2. Amounts of some components in the denture adhesive formulations of the embodiments and comparative examples in this application.

[0091] Examples 2-5 This embodiment provides a polymeric composite denture adhesive. The difference between this embodiment and Embodiment 1 lies in the amount of hydrophobically modified chitosan added, as shown in Table 2. All other operating steps remain the same as in Embodiment 1.

[0092] Example 6

[0093] This embodiment provides a polymeric composite denture adhesive. The difference between this embodiment and Embodiment 3 is that, based on Embodiment 3, amino-modified hydroxypropyl methylcellulose is added, as shown in Table 2. All other operating steps remain the same as in Embodiment 3.

[0094] Example 7

[0095] This embodiment provides a polymeric composite denture adhesive. The difference between this embodiment and Embodiment 3 is that, based on Embodiment 3, aldehyde-modified polyethylene glycol diacrylate is added, as shown in Table 2. All other operating steps remain the same as in Embodiment 3.

[0096] Example 8

[0097] This embodiment provides a polymeric composite denture securing paste. The difference between this embodiment and Embodiment 3 is that, based on Embodiment 3, amino-modified hydroxypropyl methylcellulose and aldehyde-modified polyethylene glycol diacrylate are also added, with the specific amounts shown in Table 2. The timing of adding amino-modified hydroxypropyl methylcellulose is consistent with the timing of adding CMC. The timing of adding aldehyde-modified polyethylene glycol diacrylate is before adding methylparaben. All other operating steps are consistent with Embodiment 3.

[0098] Examples 9-12 This embodiment provides a polymeric composite denture adhesive. The difference between this embodiment and Embodiment 8 lies in the amount of aminopropyl methylcellulose added, as shown in Table 2. All other operating steps remain the same as in Embodiment 8.

[0099] Examples 13-16 This embodiment provides a polymeric composite denture adhesive. The difference between this embodiment and Embodiment 10 lies in the amount of aldehyde-modified polyethylene glycol diacrylate added, as shown in Table 2. All other operating steps remain the same as in Embodiment 10.

[0100] Comparative Example 1 This comparative example provides a denture securing paste. The difference between this denture securing paste and Example 1 is that it does not contain hydrophobically modified chitosan, as detailed in Table 2. All other operating steps are consistent with Example 1.

[0101] Performance testing The denture adhesive provided in the above embodiments and comparative examples were tested as follows.

[0102] (a) Basic Project Test The above-mentioned denture adhesive was tested according to the items shown in Table 3.

[0103] Table 3 Judgment Criteria and Testing Methods for Basic Item Tests

[0104] The denture adhesive provided in this application was subjected to the above-mentioned tests, and the test results all met the above-mentioned judgment criteria. Therefore, it can be seen that the denture adhesive provided in this application meets the corresponding requirements in terms of appearance, pH value, and viscosity.

[0105] (ii) Core function performance test, the test results are shown in Table 4.

[0106] (1) Bond strength test Reference standards: GB / T 7124-2023 Determination of tensile shear strength of adhesives, ISO 11609:2019 Dental materials Test methods.

[0107] Test subjects: denture base (small test piece made of PMMA material, dimensions: 25mm long × 10mm wide × 2mm thick), simulated oral mucosa (small test piece made of medical silicone rubber, dimensions: 25mm long × 10mm wide × 2mm thick).

[0108] The detection method is as follows: Sample preparation: Apply an appropriate amount of denture bonding paste evenly to the bonding area of ​​the PMMA specimen (10mm × 10mm), with a thickness controlled at 0.1-0.2mm. Immediately after application, attach the bonding surface of the silicone rubber specimen and gently press with a force of 5N. Then place it in a "simulated human oral environment" (temperature 37℃, humidity 95%) for 30 minutes to form a bonded specimen. Prepare 5 parallel samples for each test sample.

[0109] Test procedure: The bonded specimen is placed on the fixture of the tensile testing machine. The machine is set to pull slowly at a speed of 5 mm per minute along a direction parallel to the bonded surface (shear direction). The maximum tensile force when the specimen is pulled apart is recorded.

[0110] Calculation method: Bond strength (unit: kPa) = maximum tensile force (N) ÷ bonded area (converted to square meters, 10mm × 10mm = 0.0001m²), the result is the average of 5 specimens. Judgment criterion: bond strength ≥ 30kPa.

[0111] (2) Anti-chewing stability test Reference standards: ISO 11609:2019 "Dental materials - Test methods", YY / T 0113 "Dental materials - Mastication test".

[0112] Test object: The same bonding specimen prepared as in the "bonding strength test".

[0113] The detection method is as follows: Sample preparation: Similar to the method for "bond strength test", 5 bonding specimens are made for each sample to be tested.

[0114] Test procedure: Fix the bonded specimen onto the clamp of the chewing simulation testing machine, and set the machine parameters as follows: temperature 37℃ (consistent with oral temperature), biting force 50N (equivalent to the force of normal chewing), chewing 60 times per minute, continuously simulating chewing for 2 hours. After chewing, remove the specimen and measure its remaining bond strength according to the "bond strength test" method.

[0115] Calculation method: Chewing stability retention rate (%) = (Residual bond strength after chewing ÷ Initial bond strength before chewing) × 100%, and the result is the average of 5 specimens. Judgment criterion: Retention rate ≥ 80%.

[0116] (3) Stability test against drinking water flushing Reference standard: ISO 10271:2011 Dental materials - Oral environment simulation cycle testing.

[0117] Test object: The same bonding specimen prepared as in the "bonding strength test".

[0118] The detection method is as follows: Sample preparation: Similar to the method for "bond strength test", 5 bonding specimens are made for each sample to be tested.

[0119] Test procedure: Place the bonded specimen into a device for circulating artificial saliva. Set the parameters as follows: temperature 37℃, saliva flow rate 5 mL / min, and replace with fresh saliva every 30 minutes for a total of 10 times (simulating frequent drinking). After rinsing, remove the specimen and measure its remaining bond strength according to the "bond strength test" method.

[0120] Calculation method: Retention rate of water erosion resistance (%) = (Residual bond strength after erosion ÷ Initial bond strength before erosion) × 100%, and the result is the average of 5 specimens. Judgment criterion: Retention rate ≥ 75%.

[0121] (4) Long-term stability test Reference standard: ISO 11609:2019 Dental materials, Test methods.

[0122] Test object: The same bonding specimen prepared as in the "bonding strength test".

[0123] The detection method is as follows: Sample preparation: Prepare the same bonding specimens as in the "Bond Strength Test".

[0124] Test procedure: Place all bonded specimens in a simulated human oral cavity environment (37℃, 95% humidity). Take one specimen every 30 minutes after standing, and measure its current bond strength according to the "bond strength test" method.

[0125] Judgment method: Record the duration for which the bond strength drops to 50% of the initial bond strength; repeat the test 3 times and take the average of the 3 results. Judgment criterion: The duration is between 12-18 hours.

[0126] (5) Ease of picking test Reference standard: YY / T 0871 "Test of removable performance of dental denture adhesive".

[0127] Test object: The same bonding specimen prepared as in the "bonding strength test".

[0128] The detection method is as follows: Sample preparation: Similar to the method for "bond strength test", 5 bonding specimens are made for each sample to be tested.

[0129] Test procedure: After placing the bonded specimen in a simulated human oral cavity environment for 18 hours, remove the specimen and mount it on the fixture of a tensile testing machine. Set the machine to pull the specimen apart slowly at a speed of 2 mm per minute along a direction perpendicular to the bonded surface. Record the maximum tensile force (removal force, unit: N) when the specimen is completely separated. After separation, examine the bonded surface using a stereomicroscope and measure the proportion of residual paste to the total area of ​​the bonded surface.

[0130] Calculation method: The removal force is the average of 5 specimens, and the residual area ratio is the average of 5 specimens.

[0131] Judgment criteria: Picking force ≤ 5N (roughly equivalent to the weight of half a bottle of mineral water), residual area ≤ 5%.

[0132] Table 4. Performance Test Results of Core Functions

[0133] As shown in Table 4, by adjusting the amount of hydrophobically modified chitosan added in Examples 1-5, the bonding strength increased from 32 kPa to 38 kPa, changing from "close to the standard" to "far exceeding the ≥30 kPa limit"; the anti-chewing retention rate increased from 82% to 87%, and the anti-water erosion retention rate increased from 76% to 85%, meeting the requirements of "tolerance to excessive chewing and frequent drinking"; the residual area ratio decreased from 4.6% to 3.8%, gradually approaching the "≤5%" standard. In contrast, Comparative Example 1, without the addition of this component, had a bonding strength of only 25 kPa and an anti-chewing retention rate of 60%, failing to meet the core performance standards.

[0134] By introducing a combination of amino-modified hydroxypropyl methylcellulose (amino site) and aldehyde-modified polyethylene glycol diacrylate (aldehyde site) in Examples 8-16, the duration of action is directly increased to 12.5-18 hours, precisely covering the requirement of "12-18 hours of long-lasting effect". In contrast, Examples 6-7, which only added a single crosslinking component, only have a duration of 9-9.5 hours. At the same time, after adding the crosslinking system, the bonding strength increased from 36 kPa in Example 3 to 48 kPa, the chewing resistance retention rate increased from 85% to 94%, and the drinking water erosion resistance retention rate increased from 79% to 89%, further enhancing the effect of "high adhesion and resistance to scene interference". The removal force decreased from 4.3 N to 3.3 N, and the residual area ratio decreased from 4.1% to 3%, meeting the requirement of convenient removal.

[0135] Based on the above, the denture adhesive provided in this application has high bonding strength, can withstand the high stability requirements of scenarios such as excessive chewing and frequent drinking, and can achieve long-term stability for 12-18 hours, and is easy to remove after use.

[0136] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A polymeric composite denture adhesive, characterized in that, The denture bonding paste specifically comprises the following components in parts by weight: 10-20 parts white oil; 20-40 parts petrolatum; 20-40 parts CMC; 20-40 parts PVM-MA; and 0.1-1 parts silica. 0.1-1 part of 95% ethanol; 0.05-1 part of methylparaben; 0.05-1 part of menthol; Peppermint oil, 0.05-1 part; Azorubicin 0.001-0.01 parts; 8-12 parts of hydrophobically modified chitosan.

2. The denture securing paste according to claim 1, characterized in that, The hydrophobically modified chitosan is present in 9-11 parts by weight.

3. The denture securing paste according to claim 1, characterized in that, The method for preparing the hydrophobically modified chitosan includes the following steps: (1) Chitosan dissolution: Add chitosan to glacial acetic acid solution and stir at room temperature until completely dissolved to form a uniform, transparent, viscous solution; (2) Schiff base formation: Slowly add octanal or dodecyl ethanol to chitosan solution; maintain system temperature at 42-48℃, stir at 150-200r / min in the dark for 7-11h to form a uniform yellow transparent Schiff base intermediate solution. (3) Reduction reaction: Cool the reaction solution to room temperature naturally, and slowly adjust the pH to 9-10 with NaOH solution; add sodium borohydride in portions, maintaining the pH at 9-10 during the addition process, and stir the reaction at 150-200 r / min for 2.5-3.5 h. (4) Product purification: After the reaction is completed, the pH is slowly adjusted to 6.2-6.8 with HCl solution; the neutralized solution is slowly poured into anhydrous ethanol to precipitate, and the white solid is collected by filtration; the product is washed 2-3 times with anhydrous ethanol and distilled water in sequence, and then dried under vacuum to obtain a white or light yellow powder product.

4. The denture securing paste according to claim 1, characterized in that, The denture adhesive also includes 10-15 parts of amino-modified hydroxypropyl methylcellulose and 2-5 parts of aldehyde-modified polyethylene glycol diacrylate.

5. The denture securing paste according to claim 4, characterized in that, The amino-modified hydroxypropyl methylcellulose is present in parts by weight of 12-14.

6. The denture securing paste according to claim 4, characterized in that, The aldehyde-based polyethylene glycol diacrylate is present in parts by weight of 3-4 parts.

7. The denture securing paste according to claim 4, characterized in that, The method for preparing the amino-modified hydroxypropyl methylcellulose includes the following steps: (1) Alkalization treatment: HPMC is added to a mixed solvent of isopropanol and water and stirred at room temperature until completely dissolved; NaOH solution is slowly added dropwise to adjust the pH to 10-12, the temperature is maintained at 25-35℃, and the reaction is stirred for 1-2 hours to form an alkaline cellulose solution; (2) Amination reaction: Dissolve CTA in deionized water and slowly add it dropwise to the alkaline cellulose solution; heat to 65-75℃ and stir at 150-200r / min for 4-6h under nitrogen protection, maintaining pH 10-12; determination of reaction endpoint: take a small amount of sample and test with silver nitrate solution to detect no chloride ion precipitation; (3) Neutralization and purification: After the reaction is completed, cool to room temperature and adjust the pH to 7.0-7.5 with HCl; pour the solution into acetone to precipitate, filter and collect the white solid; wash with acetone and distilled water in sequence, and vacuum dry to obtain a white powder product.

8. The denture securing paste according to claim 4, characterized in that, The method for preparing the aldehyde-modified polyethylene glycol diacrylate includes the following steps: (1) PEG aldehyde hydration: Dissolve PEG in distilled water and add ethylene glycol as a protective agent; under light-protected conditions, add sodium periodate in portions, control the system temperature at 28-32℃, and stir the reaction at 150-200r / min for 4.5-5.5h. (2) PEG-CHO purification: After the reaction was completed, excess ethylene glycol was added to terminate the reaction; the reaction solution was dialyzed for 40-50 h to completely remove inorganic salts; the dialysate was freeze-dried to obtain a white flocculent PEG-CHO intermediate; (3) Acrylate modification: Dissolve PEG-CHO in anhydrous dichloromethane, add triethylamine, and cool in an ice bath; slowly add acrylic anhydride, maintaining the system temperature ≤10℃ during the addition process, and continue stirring at 150-200r / min for 1.5-2.5h under ice bath conditions; then raise the temperature to room temperature and continue stirring for 14-22h. (4) Product purification: Add sodium bicarbonate solution to the reaction solution, shake and wash, let stand and separate into layers and discard the aqueous phase; dry the organic phase with anhydrous sodium sulfate and filter to remove the desiccant; evaporate the filtrate by rotary evaporation at 35-40℃ and 0.03-0.05MPa; slowly add the concentrated product dropwise to anhydrous diethyl ether while stirring to promote complete precipitation; filter and collect the white precipitate, vacuum dry to obtain a colorless, transparent, viscous product.

9. A method for preparing a denture adhesive according to any one of claims 1-8, characterized in that, The preparation method specifically includes the following steps: (1) Put white oil and petroleum jelly into an emulsifying pot, heat to 60-80℃, and stir continuously at a stirring speed of 100-150r / min for 10-20min until the petroleum jelly is completely melted to form a uniform and continuous oil phase system; (2) Add PVM-MA to the oil phase system and stir at a stirring speed of 150-200 r / min for 50-70 min to make PVM-MA uniformly dispersed in the oil phase; (3) Add CMC, hydrophobically modified chitosan and silica to the system, and continue stirring at a stirring speed of 200-250 r / min for 50-70 min to ensure that CMC, silica and oil phase and PVM-MA are fully integrated; (4) Add methylparaben, peppermint oil, menthol, azorubin and 95% ethanol to the system in sequence, then evacuate to -0.05~-0.1MPa, stir at a stirring speed of 250-300r / min for 1.5-2.5h to ensure that all excipients are thoroughly mixed, and the denture fixation paste is obtained.

10. The preparation method according to claim 9, characterized in that, The denture fixative also includes amino-modified hydroxypropyl methylcellulose and aldehyde-modified polyethylene glycol diacrylate; Optionally, the timing of adding the amino-modified hydroxypropyl methylcellulose is consistent with the timing of adding CMC; Optionally, the aldehyde-modified polyethylene glycol diacrylate is added before the addition of methylparaben.

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