Tooth correction material, preparation method thereof, dental orthodontic appliance and dental orthodontic retainer

Abstract

The invention discloses a tooth correction material and a preparation method thereof, a dental orthodontic appliance and a dental orthodontic retainer, the tooth correction material is made of copolyester, the structural formula of the copolyester is as shown in the formula 1, # imgabs0 contains a structural unit I derived from terephthalic acid, a structural unit II derived from isosorbide, a structural unit II derived from 1, 3-butanediol, a structural unit II derived from 1, 3-butanediol, a structural unit II derived from 1, 3-butanediol, a structural unit II derived from 1, 3-butanediol and a structural unit II derived from 1, 3-butanediol. The structural unit III is derived from 1, 4-cyclohexanedimethanol; the structural unit IV is derived from ethylene glycol; the copolyester has the following characteristics: the light transmittance is not less than 85%, and the haze is lt; 2%, the bending modulus is not greater than 1900 MPa, the bending strength is not less than 50 MPa, and the glass transition temperature is not less than 85 DEG C. The copolyester film provided by the invention has excellent transparency, heat resistance and environmental stress relaxation resistance, is simple in processing technology, and is suitable for preparing invisible dental orthodontic appliances and retainers.

Description

Technical Field

[0001] The invention relates to a tooth invisible orthodontic material, in particular to a tooth correction material and a preparation method thereof, a dental orthodontic appliance and a dental orthodontic retainer. Background Art

[0002] In recent years, people's attention and demand for oral health have increased significantly, and dental orthodontics and restoration are hot topics. Because of its aesthetic, convenient and good therapeutic effect, invisible orthodontics has gradually become a new treatment that can replace metal brackets. The appliances and retainers used in treatment are prepared by thermoforming high-transmittance polymer membranes on 3D printed dental molds. The optical, mechanical and heat resistance properties of appliances and retainers all depend on the material of the membrane, so this high-value consumable membrane places high demands on materials science.

[0003] The earliest invisible orthodontic appliance was made of a hard polyurethane diaphragm, whose mechanical properties could not fully meet clinical requirements, and was criticized for its optical properties and biosafety. Subsequently, many companies adopted materials such as PETG copolyester (polyethylene terephthalate-1,4-cyclohexanedimethanol ester) to produce transparent braces and retainers. The PETG material has good transparency, strong rigidity but weak toughness, and low heat deformation temperature, which makes it heat-resistant and prone to stress cracking during use. In addition, existing invisible braces usually have stress relaxation behavior during use. Therefore, the orthodontic force provided during the correction process cannot be maintained continuously and stably, and sometimes it is difficult to obtain satisfactory orthodontic effects, thereby reducing the treatment efficiency. This mechanical behavior is mainly related to the stress relaxation resistance of the material of the dental diaphragm itself. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a dental correction material and a preparation method thereof, a dental orthodontic appliance and a dental orthodontic retainer. The dental correction material is an amorphous copolyester transparent film required for the preparation of a dental appliance or a retainer. The copolyester in the present invention is an amorphous copolyester, which contains a structural unit 1 derived from terephthalic acid, a structural unit 2 derived from isosorbide, a structural unit 3 derived from 1,4-cyclohexanedimethanol and a structural unit 4 derived from ethylene glycol; in terms of molar fraction, relative to 100 parts of the structural unit 1, the content of the structural unit 2 is 0.5-30 parts, the content of the structural unit 3 is 51-70 parts, and the content of the structural unit 4 is the difference between 100 parts and the sum of the contents of the structural unit 2 and the structural unit 3. In common understanding, commercial copolyesters with similar structures are generally used in fields such as fibers, films, bottles or engineering plastics. PCTG (polyethylene terephthalate-1,4-cyclohexanedimethanol ester, ethylene glycol-derived structural units are not more than 50 mol%) is a crystalline copolyester, and its optical properties and processing conditions are difficult to meet the needs of dental braces. When PETG is used as an orthodontic material, it is criticized for its high modulus and obvious stress relaxation that affects the treatment effect.

[0005] The inventors of the present invention have found in their research that the introduction of isosorbide as the third diol monomer allows the structural units of the above four monomers to cooperate synergistically, which can effectively destroy the regular structure of the molecular chain and make it difficult to crystallize, so that the copolyester is in an amorphous state and thus has excellent transparency; and in this case, the four structural units act synergistically to improve the heat resistance, toughness and environmental stress relaxation resistance of the copolyester, so that it can effectively maintain its mechanical properties in the oral environment, and is very suitable as a dental orthodontic material. This discovery has broadened the source of dental orthodontic materials; not only that, the copolyester in the present invention is prepared by using a titanium-based catalyst with high biocompatibility and extremely low dosage, which can meet the safety requirements of medical devices, and with the optimization and adjustment of the catalytic system and the copolymerization ratio, it has better optical and mechanical properties than the dental orthodontic material obtained by blending polymer raw materials.

[0006] In order to achieve the above-mentioned object, the present invention provides a dental correction material in the first aspect, wherein the material of the dental correction material is copolyester, and the structural formula of the copolyester is shown in Formula 1, and contains a structural unit 1 derived from terephthalic acid, a structural unit 2 derived from isosorbide, a structural unit 3 derived from 1,4-cyclohexanedimethanol, and a structural unit 4 derived from ethylene glycol;

[0007]

[0008] In terms of molar amount, relative to 100 parts of structural unit 1, the content of structural unit 2 is 0.5-30 parts, the content of structural unit 3 is 51-70 parts, and the content of structural unit 4 is the difference between 100 parts and the sum of the contents of structural unit 2 and structural unit 3;

[0009] The copolyester has the following characteristics:

[0010] The transmittance is not less than 85%, the haze is <2%, the flexural modulus is not greater than 1900MPa, the flexural strength is not less than 50MPa, and the glass transition temperature is not less than 85°C.

[0011] According to the present invention, in terms of molar amount, relative to 100 parts of structural unit 1, the content of structural unit 2 is 0.5-30 parts, the content of structural unit 3 is 51-70 parts, the content of structural unit 4 is 100 parts minus the difference between the sum of the contents of structural unit 2 and structural unit 3, and the content of structural unit 4 is not 0 parts. Preferably, in terms of molar amount, relative to 100 parts of structural unit 1, the content of structural unit 2 derived from isosorbide is 0.5-20 parts, the content of structural unit 3 derived from 1,4-cyclohexanedimethanol is 55-70 parts, the content of structural unit 4 derived from ethylene glycol is 100 parts minus the difference between the sum of the contents of structural unit 2 and structural unit 3, and the content of structural unit 4 is not 0 parts.

[0012] In a preferred embodiment of the present invention, the copolyester is obtained by polycondensing monomer raw materials including terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol under the synergistic action of a titanium bimetallic catalyst, a hindered phenol compound and a phosphite compound; more preferably,

[0013] The titanium bimetallic catalyst, hindered phenol compound, phosphite compound and ethylene glycol are mixed and configured into a solution through complex reaction, and then added into a slurry containing terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol to carry out polycondensation reaction.

[0014] In a further more preferred embodiment of the present invention, the process of the polycondensation reaction comprises:

[0015] Add the ethylene glycol solution of titanium bimetallic catalyst, hindered phenol compound and phosphite compound to the slurry containing terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol, mix and carry out esterification reaction at 230-260°C to obtain copolyester oligomer; then carry out pre-polycondensation reaction and final polycondensation reaction in sequence at 250-280°C, preferably the pressure of pre-polycondensation reaction is 0.5-5kPa, and the pressure of final polycondensation reaction is preferably 50-500Pa; obtain copolyester melt, cool and solidify to obtain copolyester. The above pressures are absolute pressures.

[0016] In a preferred embodiment of the present invention, the molar ratio of terephthalic acid to isosorbide and 1,4-cyclohexanedimethanol is 1:(0.1-0.5):(0.5-0.75), and the molar ratio of terephthalic acid to the total amount of isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol is 1:(1.05-1.3).

[0017] In a preferred embodiment of the present invention, relative to the total weight of all monomer raw materials, the addition amount of the titanium bimetallic catalyst is 5-50 ppm, the addition amount of the hindered phenol compound is 8-150 ppm, and the addition amount of the phosphite compound is 20-150 ppm.

[0018] In a preferred embodiment of the present invention, the other metal element in addition to titanium in the titanium-based bimetallic catalyst is magnesium; more preferably,

[0019] The structural formula of the titanium-based bimetallic catalyst is shown in Formula 2.

[0020]

[0021] In a preferred embodiment of the present invention, the copolyester is prepared by the following method:

[0022] (1) mixing terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol to obtain a slurry; preferably, the mixing conditions include: a temperature of 80-100° C. and a time of 0.3-2 hours;

[0023] (2) Mixing a titanium-magnesium bimetallic catalyst, a hindered phenol compound, and a phosphite compound with ethylene glycol to obtain a solution through a complexation reaction; preferably, the content of ethylene glycol in the solution is 98-99.5 wt %.

[0024] (3) Adding the solution obtained in step (2) to the slurry obtained in step (1), and subjecting the mixture to esterification reaction and polycondensation reaction to obtain the copolyester.

[0025] In a preferred embodiment of the present invention, the hindered phenol compound is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-methylphenol, 2,4-dimethyl-6-(1-methylpentadecyl)-phenol, and 4,4'-methylenebis(2,6-di-tert-butylphenol); and / or

[0026] The phosphite compound is at least one selected from tris(2,4-di-tert-butyl)phenyl phosphite, 4,4'-biphenyl diphosphite, distearyl pentaerythritol diphosphite, and bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite.

[0027] As described above, the copolyester has the following characteristics: light transmittance is not less than 85%, haze <2%, bending modulus is not more than 1900MPa, bending strength is not less than 50MPa, and glass transition temperature is not less than 85°C. In a more preferred embodiment of the present invention, the copolyester has at least one of the following characteristics:

[0028] The dental correction material is a copolyester film, preferably with a thickness of 0.5-1 mm;

[0029] The glass transition temperature of the copolyester polymer is 85-120°C;

[0030] The heat distortion temperature of the copolyester polymer is 75-105°C;

[0031] The flexural modulus of the copolyester polymer is 1500-1900 MPa;

[0032] The flexural strength of the copolyester polymer is 50-65 MPa;

[0033] The light transmittance of the copolyester polymer is 85%-92%;

[0034] The terminal carboxyl content is not higher than 40 mol / t;

[0035] The copolyester is an amorphous copolyester;

[0036] Chroma b value is not higher than 10;

[0037] The intrinsic viscosity is 0.6-0.8dL / g;

[0038] The content of diethylene glycol is not higher than 1.5 mol%.

[0039] The second aspect of the present invention is to provide a method for preparing the dental correction material described in the first aspect, comprising subjecting the copolyester to melt extrusion casting, injection molding or compression molding to obtain the dental correction material;

[0040] The preferred molding temperature is 200°C - 250°C.

[0041] The film prepared from the copolyester polymer can be used as a dental correction material in the field of preparing transparent dental orthodontic appliances and retainers.

[0042] The third aspect of the present invention is to provide a use of the dental correction material described in the first aspect or the dental correction material obtained by the preparation method described in the second aspect as a dental invisible orthodontic correction material; preferably used for dental orthodontic appliances and / or dental orthodontic retainers;

[0043] More preferably, it is used for transparent orthodontic appliances and / or transparent orthodontic retainers.

[0044] The fourth aspect of the present invention is to provide a dental orthodontic appliance, the dental orthodontic appliance comprising the dental orthodontic material described in the first aspect or the dental orthodontic material obtained by the preparation method described in the second aspect;

[0045] Preferably, the orthodontic appliance is a transparent orthodontic appliance.

[0046] The fifth aspect of the present invention is to provide a dental orthodontic retainer, the dental orthodontic retainer comprising the dental orthodontic material described in the first aspect or the dental orthodontic material obtained by the preparation method described in the second aspect;

[0047] Preferably, the orthodontic retainer is a transparent orthodontic retainer.

[0048] The advantages of the present invention are:

[0049] The present invention uses a specific amorphous copolyester film as a tooth correction material. The structural formula of the copolyester is shown in Formula 1, which contains a structural unit 1 derived from terephthalic acid, a structural unit 2 derived from isosorbide, a structural unit 3 derived from 1,4-cyclohexanedimethanol, and a structural unit 4 derived from ethylene glycol;

[0050]

[0051] In terms of molar amount, relative to 100 parts of structural unit 1, the content of structural unit 2 is 0.5-30 parts, the content of structural unit 3 is 51-70 parts, and the content of structural unit 4 is 100 parts minus the sum of the contents of structural unit 2 and structural unit 3; the copolyester has the following characteristics: light transmittance is not less than 85%, haze is less than 2%, bending modulus is not more than 1900MPa, bending strength is not less than 50MPa, and glass transition temperature is not less than 85°C.

[0052] The tooth correction material of the present invention has excellent transparency, heat resistance and resistance to environmental stress relaxation, and has a simple processing technology, and is suitable for preparing invisible dental orthodontic appliances and retainers. DETAILED DESCRIPTION

[0053] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0054] The performance test items of the polyester chips in the embodiments and comparative examples are as follows: intrinsic viscosity η (dL / g), test method: refer to GB / T14190-2008; terminal carboxyl content (mol / t), test method: refer to GB / T14190-2008; diethylene glycol content (%), test method: refer to GB / T 14190-2008. Chromaticity b value test method: Konica Minolta CM-5 spectrophotometer is used for testing;

[0055] The various mechanical and optical properties of the copolyesters in the embodiments and comparative examples were prepared by injection molding and measured according to national standards: including heat deformation temperature (GB / T1634.2-2019), flexural modulus (GB / T9341-2008), light transmittance and haze (GB / T2410-2008) and simply supported beam notched impact performance (abbreviated as simply supported beam notched impact) (GB / T1043.1-2008).

[0056] The stress relaxation performance test equipment is Shimadzu Universal Mechanical Testing Machine. The dumbbell-shaped specimens punched out from the cast film were soaked in 40 degrees Celsius water for 16 hours before testing. The sample was stretched to a strain of 2.5% and kept constant. The stress value was tested to change with time. The test cycle was 1 hour, and the ratio of stress to initial stress was recorded at the end of the test.

[0057] The actual chemical composition of the copolyesters was studied using a 600 MHz nuclear magnetic resonance spectrometer (Bruker AVANCE III), deuterated trifluoroacetic acid (TFA) was used as the polyester solvent, and tetramethylsilane (TMS) was used as the internal standard.

[0058] Glass transition temperature (°C), test method: tested by Perkin Elmer DSC 8000 differential scanning calorimeter at a heating and cooling rate of 20°C / min, sample T g The midpoint of the heat capacity transition of the second heating curve is taken;

[0059] Titanium-magnesium bimetallic catalyst Reference Cost-Effective Sustainable Synthesis of High-Performance High-Molecular-WeightPoly(trimethylene terephthalate) by Eco-Friendly and Highly Active Ti / MgCatalysts (DOI: 10.1021 / acssuschemeng.6b02358).

[0060] The pressures of the preliminary polycondensation reaction and the final polycondensation reaction in the present invention are absolute pressures.

[0061] Example 1

[0062] According to the preparation method provided by the present invention, copolyester chips, test samples and dental correction materials are prepared, and the specific steps are as follows:

[0063] 1) Copolyester polymerization:

[0064] (1) Terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol were added into a reaction kettle in a molar ratio of 1:0.10:0.55:0.40 to prepare a slurry, wherein the slurry preparation time was 1.5 hours and the temperature was 90°C.

[0065] (2) A titanium-magnesium bimetallic catalyst, 2,6-di-tert-butyl-4-methylphenol, 4,4'-biphenyl diphosphite and ethylene glycol are mixed at 80° C. and prepared into a solution through a complexation reaction.

[0066] (3) adding an ethylene glycol solution of a titanium magnesium bimetallic catalyst / 2,6-di-tert-butyl-4-methylphenol / 4,4'-biphenyl diphosphite into a reactor and mixing the mixture evenly with the slurry prepared in step (1), adjusting the heat medium temperature of the reactor to 240° C., and performing an esterification reaction to obtain a heat-resistant polyester oligomer, wherein the ethylene glycol content of the ethylene glycol solution of the titanium magnesium bimetallic catalyst / 2,6-di-tert-butyl-4-methylphenol / 4,4'-biphenyl diphosphite is 98 wt %; relative to the weight of the heat-resistant polyester, the addition amount of the titanium magnesium bimetallic catalyst is 15 ppm, the addition amount of 2,6-di-tert-butyl-4-methylphenol is 80 ppm, and the addition amount of 4,4'-biphenyl diphosphite is 80 ppm.

[0067] (4) The heat medium temperature of the reactor is adjusted to 250° C., and the heat-resistant polyester oligomer obtained in step (3) is subjected to a pre-polycondensation reaction and a final polycondensation reaction in sequence to obtain a heat-resistant polyester melt, wherein the pre-polycondensation reaction pressure is 0.5 kPa and the final polycondensation reaction pressure is 200 Pa.

[0068] (5) The heat-resistant polyester melt prepared in step (4) is filtered through a filter and then sent to a casting head for cooling and solidification, and then pelletized by a pelletizer to obtain heat-resistant polyester chips.

[0069] 2) After the raw material obtained in the polymerization step (5) is dried, it is injection molded to obtain specimens and samples for mechanical and optical property tests, and the processing temperature is controlled at 230° C.-250° C.

[0070] 3) After drying the raw material obtained in the polymerization step (5), melt extrusion casting is performed using a single screw extruder, the screw speed is 15r / min, the processing temperature is controlled between 200°C and 250°C, and the thickness of the cast sheet is controlled to be 0.75mm-0.8mm. The cast sheet is cut to obtain a circular copolyester film, which is used as a dental correction material.

[0071] Example 2

[0072] 1) Copolyester polymerization:

[0073] Terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol were added into a reactor at a molar ratio of 1:0.15:0.65:0.40 to prepare slurry, wherein the slurry preparation time was 1.5 hours and the temperature was 90°C.

[0074] The catalyst configuration, antioxidant addition, esterification and polycondensation conditions, and granulation process are the same as (2) to (5) in step 1) of Example 1.

[0075] 2) The injection molding process is the same as step 2) of Example 1.

[0076] 3) The tape casting process is the same as step 3) of Example 1.

[0077] Example 3

[0078] 1) Copolyester polymerization:

[0079] (1) Terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol were added into a reaction kettle in a molar ratio of 1:0.3:0.65:0.15 to prepare a slurry, wherein the slurry preparation time was 1.5 hours and the temperature was 90°C.

[0080] The catalyst configuration, antioxidant addition, esterification and polycondensation conditions, and granulation process are the same as (2) to (5) in step 1) of Example 1.

[0081] 2) The injection molding process is the same as step 2) of Example 1.

[0082] 3) The tape casting process is the same as step 3) of Example 1.

[0083] Example 4

[0084] 1) Copolyester polymerization:

[0085] (1) Terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol are added into a reaction kettle in a molar ratio of 1:0.5:0.55:0.15 to prepare a slurry; wherein the slurry preparation time is 1.5 hours and the temperature is 90°C.

[0086] (2) A titanium-magnesium bimetallic catalyst, 2,6-di-tert-butyl-4-methylphenol, tri(2,4-di-tert-butyl)phenyl phosphite and ethylene glycol are mixed and prepared into a solution through a complexation reaction at 120° C., wherein the ethylene glycol content in the solution is 98 wt %.

[0087] (3) adding the solution obtained in step (2) into a reactor and mixing evenly with the slurry prepared in step (1), adjusting the heat medium temperature of the reactor to 240° C., and performing an esterification reaction to obtain a heat-resistant polyester oligomer; wherein, relative to the weight of the polyester, the amount of the titanium-magnesium bimetallic catalyst added is 5 ppm, the amount of 2,6-di-tert-butyl-4-methylphenol added is 50 ppm of the polyester melt, and the amount of tri(2,4-di-tert-butyl)phenyl phosphite added is 80 ppm of the polyester melt.

[0088] (4) The heat medium temperature of the reaction kettle is adjusted to 255° C., and the oligomer obtained in step (3) is subjected to a pre-polycondensation reaction and a final polycondensation reaction in sequence to obtain a heat-resistant polyester melt; wherein the pre-polycondensation reaction pressure is 3 kPa, and the final polycondensation reaction pressure is 250 Pa.

[0089] (5) The heat-resistant polyester melt prepared in step (4) is filtered through a filter and then sent to a casting head for cooling and solidification, and then pelletized by a pelletizer to obtain heat-resistant polyester chips.

[0090] 2) The injection molding process is the same as step 2) of Example 1.

[0091] 3) The tape casting process is the same as step 3) of Example 1.

[0092] Example 5

[0093] 1) Copolyester polymerization:

[0094] (1) Terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol were added into a reaction kettle in a molar ratio of 1:0.15:0.75:0.40 to prepare a slurry, wherein the slurry preparation time was 1.5 hours and the temperature was 90°C.

[0095] The catalyst configuration, antioxidant addition, esterification and polycondensation conditions, and granulation process are the same as (2) to (5) in step 1) of Example 4.

[0096] 2) The injection molding process is the same as step 2) of Example 1.

[0097] 3) The tape casting process is the same as step 3) of Example 1.

[0098] Comparative Example 1

[0099] 1) Copolyester polymerization:

[0100] (1) Terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol were added into a reactor at a molar ratio of 1:0.3:0.55:0.35 to prepare a slurry, wherein the slurry preparation time was 0.5 h and the temperature was 100° C.

[0101] (2) The titanium-magnesium bimetallic catalyst and ethylene glycol are prepared into a solution through a complex reaction at 120°C.

[0102] (3) adding the ethylene glycol solution of the titanium-magnesium bimetallic catalyst into the reactor and mixing evenly with the slurry prepared in step (1), adjusting the heat medium temperature of the reactor to 250°C, and performing an esterification reaction to obtain a heat-resistant polyester oligomer; wherein the ethylene glycol content in the ethylene glycol solution of the titanium-magnesium bimetallic catalyst is 98wt%; and the addition amount of the titanium-magnesium bimetallic catalyst is 50ppm relative to the weight of the heat-resistant polyester.

[0103] (4) The temperature of the heat medium in the reactor is adjusted to 265° C., and the heat-resistant polyester oligomer obtained in step (3) is subjected to a pre-polycondensation reaction and a final polycondensation reaction in sequence to obtain a heat-resistant polyester melt, wherein the pre-polycondensation reaction pressure is 4 kPa and the final polycondensation reaction pressure is 50 Pa.

[0104] (5) The heat-resistant polyester melt prepared in step (4) is filtered through a filter and then sent to a casting head for cooling and solidification, and then pelletized by a pelletizer to obtain heat-resistant polyester chips.

[0105] 2) The injection molding process is the same as step 2) of Example 1.

[0106] 3) The tape casting process is the same as step 3) of Example 1.

[0107] Comparative Example 2

[0108] This comparative example is used to illustrate the preparation of copolyester chips, samples and films according to the copolymer structure of commercial PETG.

[0109] (1) Terephthalic acid, 1,4-cyclohexanedimethanol and ethylene glycol were added into a reaction kettle in a molar ratio of 1:0.35:0.85 to prepare a slurry, wherein the slurry preparation time was 1 hour and the temperature was 90°C.

[0110] The catalyst configuration, antioxidant addition, esterification and polycondensation conditions, and granulation process are the same as (2) to (5) in step 1) of Example 1.

[0111] 2) The injection molding process is the same as step 2) of Example 1.

[0112] 3) The tape casting process is the same as step 3) of Example 1.

[0113] Experimental Example 1

[0114] In order to further illustrate the beneficial effects of the present invention, the properties of the heat-resistant polyester chips prepared in Examples 1 to 5 and Comparative Example 1 were tested, and the test items were as follows: intrinsic viscosity η (dL / g), terminal carboxyl content (mol / t), diethylene glycol content (%), and chromaticity b value.

[0115] The test results are shown in Table 1.

[0116] Table 1 Performance test results of polyester chips prepared in Examples 1 to 5 and Comparative Example 1

[0117]

[0118] It can be observed from Table 1 that the chromaticity value and terminal carboxyl content of the heat-resistant polyester chips prepared in Comparative Example 1 are significantly higher than those of the heat-resistant polyester chips prepared in Example. In Comparative Example 1, titanium magnesium is used as a catalyst for the heat-resistant polyester. Since titanium ions have a high catalytic activity on the thermal degradation reaction of the heat-resistant polyester, the heat-resistant polyester produces severe yellowing, with a chromaticity b value of up to 20 and a terminal carboxyl content of up to 33 mol / t.

[0119] Experimental Example 2

[0120] The microstructures and macroscopic properties of Examples 1 to 5 and Comparative Examples 1 to 2 were compared.

[0121] The actual copolymer composition of the sample is obtained by nuclear magnetic resonance characterization, and the glass transition temperature of the sample is obtained by differential scanning calorimetry. The macroscopic properties are measured by injection molding or cast sheet, and the test contents include: heat deformation temperature, flexural modulus, light transmittance, simply supported beam notched impact performance (abbreviated as simply supported beam notched impact) and stress relaxation rate.

[0122] Table 2 Structure and glass transition temperature of copolyester chips prepared in Examples 1 to 5 and Comparative Examples 1 to 2

[0123]

[0124] In Table 2, 1,4-cyclohexanedimethanol, ethylene glycol, and isosorbide each represent a structural unit derived from a corresponding monomer, and the content of the structural unit derived from terephthalic acid is 100 mol%.

[0125] Table 3 Macroscopic properties of copolyesters prepared in Examples 1 to 5 and Comparative Example 2

[0126]

[0127]

[0128] From the macroscopic test results, it can be seen that the bending modulus of the copolyester prepared in the examples is significantly lower than that of the PETG copolyester in the comparative example. The stress relaxation test uses a relatively large strain (2.5%) to characterize the degree of mechanical attenuation of the material under deformation. From the results, it can be seen that the stress relaxation of the examples is less than that of the PETG copolyester. Combining these test results, it can be seen that the copolyester prepared in the examples can provide a more suitable and more stable correction force in the application of dental orthodontic appliances, thereby achieving a better treatment effect.

[0129] In summary, the specific copolyester used in the present invention obtains a dental correction material with excellent transparency, low chromaticity b value, good heat resistance and high resistance to environmental stress relaxation. The processing technology is simple and suitable for preparing invisible dental orthodontic appliances, retainers and other dental correction equipment.

[0130] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

[0131] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0132] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0133] The endpoints and any values ​​of the scope disclosed in the present application document are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0134] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

[0135] Moreover, any embodiment described in this document may be freely combined with one or more other embodiments described in this document, and the technical solutions or technical ideas formed thereby are deemed to be part of the original disclosure or original record of the present invention, and should not be regarded as new content that has not been disclosed or anticipated in this document, unless a person skilled in the art considers that the combination is obviously unreasonable.

Claims

1. A tooth correction material, wherein the material of the tooth correction material is copolyester, the structural formula of the copolyester is as shown in Formula 1, and contains a structural unit 1 derived from terephthalic acid, a structural unit 2 derived from isosorbide, a structural unit 3 derived from 1,4-cyclohexanedimethanol, and a structural unit 4 derived from ethylene glycol; In terms of molar amount, relative to 100 parts of structural unit 1, the content of structural unit 2 is 0.5-30 parts, the content of structural unit 3 is 51-70 parts, and the content of structural unit 4 is the difference between 100 parts and the sum of the contents of structural unit 2 and structural unit 3; The copolyester has the following characteristics: The transmittance is not less than 85%, the haze is <2%, the flexural modulus is not greater than 1900MPa, the flexural strength is not less than 50MPa, and the glass transition temperature is not less than 85°C.

2. The dental correction material according to claim 1, characterized in that: The copolyester is obtained by polycondensing monomer raw materials including terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol under the synergistic action of a titanium bimetallic catalyst, a hindered phenol compound and a phosphite compound; preferably, The titanium bimetallic catalyst, hindered phenol compound, phosphite compound and ethylene glycol are mixed and configured into a solution through complex reaction, and then added into a slurry containing terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol to carry out polycondensation reaction.

3. The dental correction material according to claim 2, characterized in that: The molar ratio of terephthalic acid to isosorbide and 1,4-cyclohexanedimethanol is 1:(0.1-0.5):(0.5-0.75), and the molar ratio of terephthalic acid to the total amount of isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol is 1:(1.05-1.3).

4. The dental correction material according to claim 2, characterized in that: Relative to the total weight of all monomer raw materials, the addition amount of the titanium-based bimetallic catalyst is 5-50 ppm, the addition amount of the hindered phenol compound is 8-150 ppm, and the addition amount of the phosphite compound is 20-150 ppm.

5. The dental correction material according to claim 2, characterized in that: The other metal element in the titanium-based bimetallic catalyst besides titanium is magnesium; preferably, The structural formula of the titanium bimetallic catalyst is shown in Formula 2.

6. The dental correction material according to claim 2, characterized in that: The hindered phenol compound is at least one selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-methylphenol, 2,4-dimethyl-6-(1-methylpentadecyl)-phenol, and 4,4'-methylenebis(2,6-di-tert-butylphenol); and / or The phosphite compound is at least one selected from tris(2,4-di-tert-butyl)phenyl phosphite, 4,4'-biphenyl diphosphite, distearyl pentaerythritol diphosphite, and bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite.

7. The dental correction material according to claim 2, characterized in that: The process of the polycondensation reaction comprises: A titanium bimetallic catalyst, an ethylene glycol solution of a hindered phenol compound and a phosphite compound are added to a slurry containing terephthalic acid, isosorbide, 1,4-cyclohexanedimethanol and ethylene glycol, and after mixing, an esterification reaction is carried out at 230-260° C. to obtain a copolyester oligomer; then a pre-polycondensation reaction and a final polycondensation reaction are carried out in sequence at 250-280° C., preferably the pressure of the pre-polycondensation reaction is 0.5-5 kPa, and the pressure of the final polycondensation reaction is preferably 50-500 Pa, to obtain a copolyester melt, which is cooled and solidified to obtain a copolyester.

8. The dental correction material according to any one of claims 1 to 7, characterized in that: The copolyester has at least one of the following characteristics: The dental correction material is a copolyester film, preferably with a thickness of 0.5-1 mm; The glass transition temperature of the copolyester polymer is 85-120°C; The heat distortion temperature of the copolyester polymer is 75-105°C; The flexural modulus of the copolyester polymer is 1500-1900 MPa; The flexural strength of the copolyester polymer is 50-65 MPa; The light transmittance of the copolyester polymer is 85%-92%; The terminal carboxyl content is not higher than 40 mol / t; Chroma b value is not higher than 10; The copolyester is an amorphous copolyester; The intrinsic viscosity is 0.6-0.8dL / g; The content of diethylene glycol is not higher than 1.5 mol%.

9. A method for preparing a dental correction material according to any one of claims 1 to 8, comprising subjecting the copolyester to melt extrusion casting, injection molding or compression molding to obtain the dental correction material; The preferred molding temperature is 200-250°C.

10. Use of the dental correction material according to any one of claims 1 to 8 or the dental correction material obtained by the preparation method according to claim 9 as a dental invisible orthodontic correction material; preferably used for dental orthodontic appliances and / or dental orthodontic retainers; More preferably, it is used for transparent orthodontic appliances and / or transparent orthodontic retainers.

11. A dental orthodontic appliance, comprising the dental orthodontic material according to any one of claims 1 to 8 or the dental orthodontic material obtained by the preparation method according to claim 9; Preferably, the orthodontic appliance is a transparent orthodontic appliance.

12. A dental orthodontic retainer, comprising the dental orthodontic material according to any one of claims 1 to 8 or the dental orthodontic material obtained by the preparation method according to claim 9; Preferably, the orthodontic retainer is a transparent orthodontic retainer.

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