Transparent resin as well as preparation method and application thereof

Abstract

The invention discloses transparent resin as well as a preparation method and application thereof, and belongs to the technical field of polyester synthesis and application and development of polyester materials. The preparation method comprises the following steps: sequentially carrying out esterification reaction and polycondensation reaction on a mixture containing dibasic acid, dihydric alcohol, a catalyst and a stabilizer to obtain transparent resin; the binary acid is selected from at least one of terephthalic acid, 2, 5-furandicarboxylic acid and 2, 5-thiophenedicarboxylic acid; the dihydric alcohol is selected from at least two of ethylene glycol, 1, 4-butanediol, 1, 4-cyclohexanedimethanol, isosorbide and 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, and the dihydric alcohol is selected from at least two of ethylene glycol, 1, 4-butanediol, 1, 4-cyclohexanedimethanol, isosorbide and 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol; the catalyst is selected from defect-state nano titanium dioxide; and the stabilizer is selected from triphenyl phosphate. By using the combination of the defect-state nano titanium dioxide catalyst and the triphenyl phosphate stabilizer, the polymerization reaction can be completed with high activity and low time consumption, and meanwhile, good transparency, excellent color, low ash content and excellent thermodynamic property of the product are kept.

Description

Technical Field

[0001] The present application relates to a transparent resin and a preparation method and application thereof, belonging to the technical field of polyester synthesis and polyester material application development. Background Art

[0002] In the field of orthodontics, traditional braces are primarily metal. However, metal braces suffer from poor aesthetics. With rising aesthetic demands, resin materials are emerging for transparent braces. Transparent polyester resins offer excellent optical clarity, making braces virtually invisible when worn, meeting patients' aesthetic needs. They also possess good flexibility and elasticity. These properties allow braces to conform to the tooth surface and effectively transmit corrective forces during the correction process, helping teeth gradually move into the correct position. From a processing perspective, transparent polyester resins are easy to process and shape. Through methods such as hot pressing or injection molding, transparent braces can be custom-made to fit the individual patient's oral shape. Furthermore, this material is chemically stable, allowing it to withstand prolonged use in the complex oral environment (such as varying pH levels, temperature fluctuations, and saliva composition) without easily deforming, aging, or releasing harmful chemicals. Transparent brace materials must meet medical grade, be biosafe, and exhibit high transparency, good mechanical properties, excellent toughness, temperature resistance, high tear resistance, and good processing properties.

[0003] Traditional polyester resins are typically prepared using a melt polymerization method, where terephthalic acid and ethylene glycol are first esterified and then polycondensed over commonly used catalysts such as tetrabutyl terephthalate, isopropyl terephthalate, stannous octoate, antimony acetate, stannous oxide, and antimony oxide. However, these commonly used catalysts often lead to issues such as high catalyst usage, high ash content, long polymerization times, and poor product color and light transmittance. Summary of the Invention

[0004] To address the aforementioned technical issues existing in the conventional art of preparing transparent dental brace materials, this application proposes a technical solution for preparing a medical-grade transparent resin. This solution utilizes a combination of defective nano-TiO2 catalyst and triphenyl phosphate stabilizer, enabling a homogeneous, highly active, and time-efficient polymerization reaction while maintaining excellent transparency, color, and low ash content. This preparation method eliminates the need to modify conventional PCTG production lines for large-scale production, resulting in stable product performance.

[0005] This application adopts the following technical solutions:

[0006] According to a first aspect of the present application, a method for preparing a transparent resin is provided, comprising the following steps:

[0007] subjecting a mixture containing a dibasic acid, a diol, a catalyst, and a stabilizer to an esterification reaction and a polycondensation reaction in sequence to obtain the transparent resin;

[0008] The dibasic acid is selected from at least one of terephthalic acid, 2,5-furandicarboxylic acid, and 2,5-thiophenedicarboxylic acid;

[0009] The diol is selected from at least two of ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, isosorbide, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol;

[0010] The catalyst is selected from defective nano-TiO2;

[0011] The stabilizer is selected from triphenyl phosphate.

[0012] The preparation of defective nano-TiO2 in this application is not strictly limited. Those skilled in the art can prepare or purchase commodities according to the prior art. The defective nano-TiO2 catalyst plays the role of efficient catalysis through the defective nano-TiO2 active site. Compared with traditional metal salts, metal complexes and metal oxide catalysts, due to its high activity, the dosage can be significantly reduced while maintaining the same catalytic activity, thereby reducing the ash content in the product and shortening the polymerization time. If it can be combined with a suitable antioxidant, the color and luster of the product can be kept excellent while achieving the above-mentioned advantages.

[0013] Optionally, the molar ratio of the diol to the dibasic acid is 1.2 to 1.7:1.

[0014] Optionally, the diol includes ethylene glycol and other alcohols;

[0015] The other alcohol is selected from at least one of 1,4-butanediol, 1,4-cyclohexanedimethanol, isosorbide, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol;

[0016] The molar ratio of the ethylene glycol to other alcohols is 1:0.01-5.

[0017] Optionally, the diol includes ethylene glycol and 1,4-cyclohexanedimethanol, and the molar ratio of the ethylene glycol to the 1,4-cyclohexanedimethanol is 1:0.01-5.

[0018] Optionally, the amount of the catalyst used is 0.001‰ to 5‰ of the total mass of the dibasic acid and the diol.

[0019] Optionally, the amount of the stabilizer used is 0.001‰ to 0.01‰ of the total mass of the dibasic acid and the diol.

[0020] Optionally, the esterification reaction conditions include: the reaction is carried out in an inert atmosphere, the reaction temperature is 180 to 245° C., and the reaction time is 0.5 to 6 hours.

[0021] Optionally, the esterification reaction is carried out under step-by-step temperature increase conditions.

[0022] Optionally, the inert atmosphere is selected from nitrogen and argon.

[0023] Optionally, the conditions for the polycondensation reaction include: the reaction is carried out under vacuum conditions, the reaction temperature is 180-270° C., and the reaction time is 0.5-8 h.

[0024] Optionally, the polycondensation reaction is carried out under step-by-step temperature increase conditions.

[0025] Optionally, the vacuum condition is: vacuum degree ≤ 200Pa.

[0026] According to a second aspect of the present application, a transparent resin obtained by the above preparation method is provided, wherein the transparent resin has at least one of the following performance characteristics:

[0027] The chromaticity b of the transparent resin is ≤ 2.0;

[0028] The light transmittance of the transparent resin is ≥93%;

[0029] The transparent resin has an intrinsic viscosity of 0.60 to 1.5 dL / g;

[0030] The tensile strength of the transparent resin is ≥50 MPa.

[0031] According to a third aspect of the present application, there is provided a transparent resin obtained by the above-mentioned preparation method or an application of the above-mentioned transparent resin in the field of orthodontics.

[0032] Optionally, the application includes using the transparent resin in transparent braces for orthodontic treatment.

[0033] The beneficial effects of this application include:

[0034] The transparent resin preparation method provided in this application utilizes highly active defective nano-TiO2 as a catalyst, enabling a homogeneous polymerization reaction and significantly reducing polymerization time. The use of triphenyl phosphate as a stabilizer allows the polymerization reaction to proceed homogeneously and significantly reduce polymerization time while maintaining excellent transparency, good color, and low ash content. The transparent resin prepared in this application exhibits excellent optical and mechanical properties, biosafety, and good processability. It can be used as a transparent brace material for orthodontic procedures. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the structural formula of the optical resin of this application;

[0036] Figure 2 This is a schematic diagram of the structure of the defective nano-TiO2 catalyst of this application. DETAILED DESCRIPTION

[0037] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0038] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0039] The source of defective nano-TiO2 is self-made, and its structural diagram is as follows Figure 1 As shown, the defective nano-TiO2 is nano-TiO2 with oxygen vacancy defects, and the EPR test spectrum is as follows Figure 2 As shown, there is a characteristic signal peak of oxygen vacancies capturing single electrons.

[0040] Unless otherwise specified, conventional methods were used for testing, and instrument settings were those recommended by the manufacturer.

[0041] The colorimeter (CS-826) used in the embodiments of the present application for measuring chromaticity and transmittance, and the Zhongwang Ubbelohde viscometer (IVS100) used for measuring intrinsic viscosity, all use the test method in GB / T 14190-2008 standard for measuring viscosity and chromaticity. The Instron electronic universal material testing machine (Instron-1121) used for measuring tensile strength was used to perform tensile tests at 25°C according to ASTM D638 requirements. The tensile speed was 5 mm / min. A dumbbell-shaped sample with a width of 3.18 mm and a thickness of 3.2 mm was prepared by injection molding using an injection molding machine, and the tensile strength of the sample was obtained.

[0042] Example 1

[0043] 0.1 mol of terephthalic acid, 0.07 mol of ethylene glycol, and 0.07 mol of 1,4-cyclohexanedimethanol (molar ratio of alcohol to acid is 1.4) were added, 0.005‰ of the total mass of the acid-alcohol feed, a defective nano-TiO2 compound catalyst, and 0.001‰ of triphenyl phosphate stabilizer were added, mixed evenly, and esterification reaction was carried out under nitrogen protection. The temperature was increased gradually, esterification at 200-240℃ for 3.5h, and polycondensation reaction was stopped at 260℃ for 2h. The obtained product polyester S1 was subjected to viscosity, optical and mechanical tests. The results are shown in Table 1.

[0044] The structural diagram of the product polyester is as follows Figure 1 shown.

[0045] Example 2

[0046] 0.1 mol of terephthalic acid, 0.08 mol of ethylene glycol, and 0.08 mol of 1,4-cyclohexanedimethanol (the molar ratio of alcohol to alcohol is 1.6) were added with 0.001‰ of the total mass of the acid-alcohol feed as a defective nano-TiO2 compound catalyst and 0.005‰ of triphenyl phosphate stabilizer. The mixture was evenly mixed and the esterification reaction was carried out under nitrogen protection. The temperature was increased gradually from 200 to 240°C for 3.5 hours, and the polycondensation reaction was stopped at 260°C for 2 hours. The obtained product polyester S2 was subjected to intrinsic viscosity, optical and mechanical tests. The results are shown in Table 1.

[0047] Example 3

[0048] 0.1 mol of terephthalic acid, 0.07 mol of ethylene glycol and 0.07 mol of 1,4-cyclohexanedimethanol were used as raw materials (the molar ratio of alcohol to acid was 1.4), and 5‰ of the total mass of the acid-alcohol feed was added as a defective nano-TiO2 compound catalyst and 0.007‰ of triphenyl phosphate stabilizer were added and mixed evenly. The esterification reaction was carried out under nitrogen protection, with a gradient temperature increase of 200-240℃ for esterification for 3.5h, and the polycondensation reaction was stopped at 260℃ for 2h. The obtained product polyester S3 was subjected to viscosity, optical and mechanical tests. The results are shown in Table 1.

[0049] Example 4

[0050] 0.1 mol of terephthalic acid, 0.06 mol of ethylene glycol, and 0.10 mol of 1,4-cyclohexanedimethanol (molar ratio of alcohol to alcohol is 1.6) were added, 0.006‰ of the total mass of the acid-alcohol feed, a defective nano-TiO2 compound catalyst, and 0.01‰ of triphenyl phosphate stabilizer were added, mixed evenly, and esterification reaction was carried out under nitrogen protection. The temperature was increased gradually, esterification was carried out at 180-240℃ for 3.0h, and polycondensation reaction was carried out at 240-260℃ for 2h to stop the reaction. The obtained product polyester S4 was subjected to viscosity, optical and mechanical tests. The results are shown in Table 1.

[0051] Example 5

[0052] 0.1 mol of terephthalic acid, 0.04 mol of ethylene glycol and 0.08 mol of 1,4-cyclohexanedimethanol were used as raw materials (the molar ratio of alcohol to acid was 1.2), and 0.001‰ of a defective nano-TiO2 compound catalyst and 0.001‰ of a triphenyl phosphate stabilizer were added and mixed evenly. The esterification reaction was carried out under nitrogen protection with a gradient temperature increase of 180-245°C for 3.0 h, and the polycondensation reaction was stopped at 240-265°C for 2 h. The obtained product polyester S5 was subjected to intrinsic viscosity, optical and mechanical tests. The results are shown in Table 1.

[0053] Example 6

[0054] 0.1 mol of terephthalic acid, 0.04 mol of ethylene glycol and 0.13 mol of 1,4-cyclohexanedimethanol were used as raw materials (the molar ratio of alcohol to acid was 1.7), and 0.5‰ of the total mass of the acid and alcohol feed was added as a defective nano-TiO2 compound catalyst and 0.01‰ of triphenyl phosphate stabilizer. The mixture was evenly mixed and the esterification reaction was carried out under nitrogen protection. The temperature was increased gradually from 180 to 235°C for 3.0 h, and the condensation reaction was stopped at 240 to 245°C for 2 h. The obtained product polyester S6 was subjected to viscosity, optical and mechanical tests. The results are shown in Table 1.

[0055] Comparative Example 1

[0056] 0.1 mol of terephthalic acid, 0.07 mol of ethylene glycol, and 0.07 mol of 1,4-cyclohexanedimethanol were used as raw materials (the molar ratio of alcohol to acid was 1.4), and 5‰ of the total mass of acid and alcohol as a stannous oxide catalyst was added and mixed evenly. The esterification reaction was carried out under nitrogen protection, with a gradient temperature increase from 200 to 240°C for 3.5 hours, and the polycondensation reaction was stopped at 260°C for 2 hours. The obtained product polyester D1 was subjected to intrinsic viscosity, optical and mechanical tests. The results are shown in Table 1.

[0057] Comparative Example 2

[0058] 0.1 mol of terephthalic acid, 0.07 mol of ethylene glycol and 0.07 mol of 1,4-cyclohexanedimethanol were used as raw materials (the molar ratio of alcohol to acid was 1.4), and 5‰ of antimony oxide catalyst was added as the total mass of acid and alcohol. The mixture was evenly mixed and the esterification reaction was carried out under nitrogen protection. The temperature was increased gradually from 200 to 240°C for esterification for 3.5 hours, and the polycondensation reaction was stopped at 260°C for 2 hours. The intrinsic viscosity, optical and mechanical tests of the obtained product polyester D2 were performed. The results are shown in Table 1.

[0059] Table 1

[0060]

[0061]

[0062] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a transparent resin, characterized in that: The steps include: subjecting a mixture containing a dibasic acid, a diol, a catalyst, and a stabilizer to an esterification reaction and a polycondensation reaction in sequence to obtain the transparent resin; The dibasic acid is selected from at least one of terephthalic acid, 2,5-furandicarboxylic acid, and 2,5-thiophenedicarboxylic acid; The diol is selected from at least two of ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, isosorbide, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; The catalyst is selected from defective nano-TiO2; The stabilizer is selected from triphenyl phosphate.

2. The preparation method according to claim 1, characterized in that The molar ratio of the diol to the dibasic acid is 1.2-1.7:

1.

3. The preparation method according to claim 1, characterized in that The diols include ethylene glycol and other alcohols; The other alcohol is selected from at least one of 1,4-butanediol, 1,4-cyclohexanedimethanol, isosorbide, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; The molar ratio of ethylene glycol to other alcohols is 1:0.01-5; Preferably, the diol includes ethylene glycol and 1,4-cyclohexanedimethanol, and the molar ratio of the ethylene glycol to the 1,4-cyclohexanedimethanol is 1:0.01-5.

4. The preparation method according to claim 1, characterized in that The amount of the catalyst used is 0.001‰ to 5‰ of the total mass of the dibasic acid and the diol.

5. The preparation method according to claim 1, characterized in that: The amount of the stabilizer used is 0.001‰ to 0.01‰ of the total mass of the dibasic acid and the diol.

6. The preparation method according to claim 1, characterized in that The conditions of the esterification reaction include: the reaction is carried out in an inert atmosphere, the reaction temperature is 180 to 245° C., and the reaction time is 0.5 to 6 hours; Preferably, the inert atmosphere is selected from nitrogen and argon.

7. The preparation method according to claim 1, characterized in that The conditions of the polycondensation reaction include: the reaction is carried out under vacuum conditions, the reaction temperature is 180-270° C., and the reaction time is 0.5-8 hours; Preferably, the vacuum condition is: vacuum degree ≤ 200Pa.

8. The transparent resin obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The transparent resin has at least one of the following performance characteristics: The chromaticity b of the transparent resin is ≤ 2.0; The light transmittance of the transparent resin is ≥93%; The transparent resin has an intrinsic viscosity of 0.60 to 1.5 dL / g; The tensile strength of the transparent resin is ≥50 MPa.

9. Use of the transparent resin obtained by the preparation method according to any one of claims 1 to 7 or the transparent resin according to claim 8 in the field of orthodontics.

10. The use according to claim 9, characterized in that The applications include using the transparent resin in transparent braces for orthodontic treatment.

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