Shape memory polymer-based 4D printed invisible orthodontic appliance material, preparation method and application thereof, and 4D printed invisible orthodontic appliance

Abstract

The invention provides a 4D printing invisible appliance material based on a shape memory polymer, a preparation method and application of the 4D printing invisible appliance material and a 4D printing invisible appliance, and belongs to the technical field of high-molecular polymer materials. The 4D printing invisible appliance material disclosed by the invention is prepared from the following raw materials in parts by mass: 100 to 500 parts of polyester polyol, 400 to 800 parts of isocyanate, 400 to 800 parts of a chain extender, 200 to 4800 parts of 1-vinyl-2-pyrrolidone, 5 to 35 parts of a photoinitiator and 1 to 15 parts of a polymerization inhibitor. The 4D printing invisible orthodontic appliance material is an invisible orthodontic appliance material with shape memory performance, the excellent shape memory performance is given to the material by utilizing a cross-linked structure and a hydrogen bond network structure of polyurethane, and shape memory response can be generated in an oral cavity temperature range; and finally, slow-release and lasting light force is applied to the teeth by the shape restoring force, so that the correction efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high molecular polymer materials, and in particular to a 4D printed invisible brace material based on shape memory polymer, a preparation method and application thereof, and a 4D printed invisible brace. Background Art

[0002] At present, the domestic and international orthodontic markets are growing rapidly. With the rapid advancement of biomaterials, computer-aided design and manufacturing technologies, invisible braces have attracted a large number of patients, especially adult patients, due to their aesthetics and comfort. The popular invisible braces materials on the current market have serious stress relaxation phenomena, which leads to problems such as excessive initial force on teeth after wearing, low tooth movement efficiency, and a large number of braces used in the whole course of treatment, which seriously affects the correction effect and the patient's experience. In addition, the existing invisible braces have a complex manufacturing process, and the vacuum hot pressing secondary molding process often leads to insufficient precision of the braces.

[0003] In recent years, shape memory polymers (SMPs), as a class of smart materials among cross-linked polymers, can autonomously recover from a temporary shape to its original shape after being subjected to specific stimuli (such as temperature changes). At the same time, due to their strong structural designability, excellent mechanical properties and adjustable shape memory transition temperature, they have gradually attracted widespread attention in the medical field.

[0004] In recent years, many scholars have tried to use 4D printing technology to make invisible braces. Through digital light projection, photosensitive resin is precisely cured, making the braces have higher precision and accuracy. In addition, it can effectively reduce costs and reduce material waste. However, the related shape memory polymers cannot produce shape memory effect at oral temperature, and the correction efficiency is low. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a 4D printed invisible braces material based on shape memory polymer, a preparation method and application thereof, and a 4D printed invisible braces. The 4D printed invisible braces material provided by the present invention can produce shape memory response within the oral temperature range, and finally exert a slow-release and lasting light force on the teeth with shape recovery force, thereby greatly improving the correction efficiency.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a 4D printing invisible orthodontic appliance material based on shape memory polymer, which is prepared from the following raw materials in parts by weight: 100 to 500 parts of polyester polyol, 400 to 800 parts of isocyanate, 400 to 800 parts of chain extender, 200 to 4800 parts of 1-vinyl-2-pyrrolidone (NVP), 5 to 35 parts of photoinitiator, and 1 to 15 parts of inhibitor.

[0008] Preferably, the polyester polyol comprises polyethylene terephthalate-1,4-cyclohexanedimethanol and / or polycarbonate diol.

[0009] Preferably, the number average molecular weight of the polycarbonate diol is 1000-2000.

[0010] Preferably, the chain extender comprises hydroxyethyl methacrylate and / or dimethylaminoethyl methacrylate.

[0011] The present invention also provides a method for preparing a 4D printed invisible orthodontic appliance material based on a shape memory polymer as described in the above technical solution, comprising the following steps:

[0012] The polyester polyol, isocyanate and chain extender are mixed to carry out prepolymerization reaction to obtain a polyurethane prepolymer (PU);

[0013] The polyurethane prepolymer, 1-vinyl-2-pyrrolidone, a photoinitiator and an inhibitor are mixed to obtain the 4D printing invisible orthodontic appliance material based on the shape memory polymer.

[0014] Preferably, the mass ratio of the polyurethane prepolymer to 1-vinyl-2-pyrrolidone is 1-3:3-1.

[0015] Preferably, the prepolymerization reaction is carried out at a temperature of 60 to 80° C. and for a time of 2 to 3 hours.

[0016] The present invention also provides the use of the 4D printing invisible braces material based on shape memory polymer described in the above technical scheme or the 4D printing invisible braces material based on shape memory polymer prepared by the preparation method described in the above technical scheme in the preparation of oral invisible braces.

[0017] The present invention also provides a 4D printed invisible braces, which is obtained by 4D printing the 4D printed invisible braces material based on shape memory polymer described in the above technical scheme or the 4D printed invisible braces material based on shape memory polymer prepared by the preparation method described in the above technical scheme.

[0018] Preferably, the parameters of the 4D printing include: ultraviolet light wavelength of 350-400 nm, irradiation time of 10-30 s / layer, and printing temperature of 20-60°C.

[0019] The present invention provides a 4D printing invisible orthodontic appliance material based on shape memory polymer, which is prepared from the following raw materials in parts by weight: 100 to 500 parts of polyester polyol, 400 to 800 parts of isocyanate, 400 to 800 parts of chain extender, 200 to 4800 parts of 1-vinyl-2-pyrrolidone, 5 to 35 parts of photoinitiator, and 1 to 15 parts of inhibitor.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The 4D printed invisible braces material provided by the present invention is an invisible braces material with shape memory properties. Compared with existing invisible braces materials, the present invention uses the cross-linked structure and hydrogen bond network structure of the polyurethane obtained by prepolymerization reaction of polyester polyol, isocyanate and chain extender to give the material excellent shape memory properties. Shape memory response can occur within the oral temperature range, and ultimately the shape recovery force can be used to apply sustained and long-lasting light force to the teeth. High-precision, personalized invisible braces that can continuously release light force in the mouth can be designed, thereby greatly improving the correction efficiency and reducing the number of braces used.

[0022] The present invention also provides a method for preparing the 4D printed invisible braces material described in the above technical solution. Compared with the secondary molding vacuum hot pressing application process of existing invisible braces materials, the 4D printed invisible braces material of the present invention is simple in preparation method on the one hand, and can be applied to 4D printing on the other hand to achieve high-precision, personalized printing and manufacturing of invisible braces.

[0023] The data of the examples show that the glass transition temperature of the material prepared in the present invention is -20 to 110°C, the yield stress is greater than 30 MPa, the yield strain is greater than 4%, the elastic modulus is greater than 1500 MPa, and the shape recovery rate within 4 days at 37°C is greater than 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 DMA test curves of the materials prepared in Examples 1 to 6 of the present invention;

[0025] Figure 2 A bar graph showing the glass transition temperatures of the materials obtained in Examples 1 to 6 of the present invention;

[0026] Figure 3 This is a shape memory demonstration diagram of the materials prepared in Examples 1 to 6 of the present invention;

[0027] Figure 4 The stress-strain curves of the materials obtained in Examples 1 to 6 of the present invention;

[0028] Figure 5 4D printing effect diagram of 4D printed invisible braces material of Example 5

[0029] Figure 6 It is the DSC curve diagram of the comparative example. DETAILED DESCRIPTION

[0030] The present invention provides a 4D printing invisible orthodontic appliance material based on shape memory polymer, which is prepared from the following raw materials in parts by weight: 100 to 500 parts of polyester polyol, 400 to 800 parts of isocyanate, 400 to 800 parts of chain extender, 200 to 4800 parts of 1-vinyl-2-pyrrolidone, 5 to 35 parts of photoinitiator, and 1 to 15 parts of inhibitor.

[0031] In the present invention, unless otherwise specified, the raw materials used are all commercially available products in the art.

[0032] The mass fraction of polyester polyol in the raw material of the 4D printing invisible orthodontic appliance material provided by the present invention is preferably 100, 200, 300, 400 or 500 parts.

[0033] In the present invention, the polyester polyol preferably includes polyethylene terephthalate-1,4-cyclohexanedimethanol and / or polycarbonate diol (PCDL).

[0034] In the present invention, the number average molecular weight of the polycarbonate diol is preferably 1,000 to 2,000.

[0035] Based on the mass of the polyester polyol, the mass fraction of isocyanate in the raw material is preferably 400, 500, 600, 700 or 800 parts.

[0036] In the present invention, the isocyanate is preferably hexamethylene diisocyanate (HDI).

[0037] Based on the mass of the polyester polyol, the mass fraction of the chain extender in the raw material is preferably 400, 500, 600, 700 or 800 parts.

[0038] In the present invention, the chain extender preferably includes hydroxyethyl methacrylate (HEMA) and / or dimethylaminoethyl methacrylate.

[0039] Based on the mass of the polyester polyol, the mass fraction of 1-vinyl-2-pyrrolidone in the raw material is preferably 200, 400, 500, 1000, 2000, 3000, 4000, 4500 or 4800 parts; the 1-vinyl-2-pyrrolidone serves as a copolymer and solvent and is a solvent for the polyurethane prepolymer, the photoinitiator and the inhibitor.

[0040] Based on the mass of the polyester polyol, the mass fraction of the photoinitiator in the raw material is preferably 5.5, 10, 15, 20, 25 or 34.5 parts.

[0041] In the present invention, the photoinitiator preferably includes one or more of 2,2-dimethoxy-2-phenylacetophenone (DMPA), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (PPO) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0042] Based on the mass of the polyester polyol, the mass fraction of the polymerization inhibitor in the raw material is preferably 1, 1.65, 3, 5, 8, 10.35 or 15 parts.

[0043] In the present invention, the polymerization inhibitor is preferably hydroquinone (also known as hydroquinone).

[0044] The present invention also provides a method for preparing a 4D printed invisible orthodontic appliance material based on a shape memory polymer as described in the above technical solution, comprising the following steps:

[0045] The polyester polyol, isocyanate and chain extender are mixed to carry out prepolymerization reaction to obtain a polyurethane prepolymer;

[0046] The polyurethane prepolymer, 1-vinyl-2-pyrrolidone, a photoinitiator and an inhibitor are mixed to obtain the 4D printing invisible orthodontic appliance material based on the shape memory polymer.

[0047] The invention mixes polyester polyol, isocyanate and chain extender to carry out prepolymerization reaction to obtain polyurethane prepolymer.

[0048] In the present invention, the prepolymerization reaction temperature is preferably 60-80° C., specifically 60, 65, 70, 75 or 80° C., and the prepolymerization reaction time is preferably 2-3 h.

[0049] The present invention preferably weighs the polyester polyol and isocyanate into a three-necked flask, heats and stirs in an oil bath at 60-80° C. for 2-3 hours, then adds the chain extender and continues stirring at 60-80° C. for 2-3 hours for prepolymerization to obtain the polyurethane prepolymer.

[0050] After obtaining the polyurethane prepolymer, the present invention mixes the polyurethane prepolymer, 1-vinyl-2-pyrrolidone, a photoinitiator and an inhibitor to obtain the 4D printing invisible orthodontic appliance material based on shape memory polymer.

[0051] In the present invention, the mass ratio of the polyurethane prepolymer to 1-vinyl-2-pyrrolidone is preferably 1-3:3-1, specifically 3:1, 2:1, 3:2, 1:1, 1:2 or 1:3.

[0052] In the present invention, the amount of the photoinitiator is preferably 0.5% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the amount of the inhibitor is preferably 0.15% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone.

[0053] The present invention preferably dissolves the polyurethane prepolymer in 1-vinyl-2-pyrrolidone, stirs for 1 hour at 60-80°C, then adds the photoinitiator and the inhibitor, and then stirs evenly at 60-80°C, and then removes bubbles from the resulting solution in a vacuum oven at 60-80°C until all bubbles are removed to obtain the 4D printed invisible brace material, which is then taken out for use.

[0054] The present invention also provides the use of the 4D printing invisible braces material based on shape memory polymer described in the above technical scheme or the 4D printing invisible braces material based on shape memory polymer prepared by the preparation method described in the above technical scheme in the preparation of oral invisible braces.

[0055] The present invention also provides a 4D printed invisible braces, which is obtained by 4D printing the 4D printed invisible braces material based on shape memory polymer described in the above technical scheme or the 4D printed invisible braces material based on shape memory polymer prepared by the preparation method described in the above technical scheme.

[0056] In the present invention, the parameters of the 4D printing preferably include: an ultraviolet light wavelength of 350 to 400 nm, an irradiation time of 10 to 30 s / layer, specifically 10, 20 or 30 s / layer, and a printing temperature of 20 to 60° C., specifically 20, 30, 40, 50 or 60° C.; a photo-initiated polymerization reaction occurs during the 4D printing process to form a polyurethane-based thermally responsive shape memory polymer.

[0057] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] Example 1

[0059] Take 30 parts by mass of polycarbonate diol (number average molecular weight is 1000) and 60 parts by mass of hexamethylene diisocyanate in a three-necked flask, heat and stir in an oil bath at 60°C for 3 hours, then add 60 parts by mass of hydroxyethyl methacrylate and continue stirring at 60°C for 3 hours to obtain a polyurethane prepolymer. Then 150 parts by mass of the prepared polyurethane prepolymer was dissolved in 50 parts by mass of 1-vinyl-2-pyrrolidone, and after stirring at 80°C for 1 hour, 1 part by mass of photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 0.3 parts by mass of inhibitor hydroquinone were added, and stirred evenly at 80°C. The obtained solution was then debubbled in a vacuum oven at 80°C until all the bubbles were removed and then 4D printed for use. A portion was taken for photocuring to form a film (ultraviolet light wavelength range is 350-400nm) (denoted as PU3NVP1, PU refers to polyurethane prepolymer, NVP is 1-vinyl-2-pyrrolidone, the subscript refers to the mass ratio, PU3NVP1 refers to the mass ratio of PU to NVP is =3:1) for testing and use, which is a polyurethane-based thermal responsive shape memory polymer.

[0060] Example 2

[0061] The same as Example 1, the only difference is that the mass ratio of PU to NVP is 2:1, and the amount of photoinitiator is 0.5% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, the amount of inhibitor is 0.15% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the photocured film is recorded as PU2NVP1.

[0062] Example 3

[0063] The same as Example 1, the only difference is that the mass ratio of PU to NVP is 3:2, and the amount of photoinitiator is 0.5% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, the amount of inhibitor is 0.15% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the photocured film is recorded as PU3NVP2.

[0064] Example 4

[0065] The same as Example 1, the only difference is that the mass ratio of PU to NVP is 1:1, and the amount of photoinitiator is 0.5% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, the amount of inhibitor is 0.15% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the photocured film is recorded as PU1NVP1.

[0066] Example 5

[0067] The same as Example 1, the only difference is that the mass ratio of PU to NVP is 1:2, and the amount of photoinitiator is 0.5% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, the amount of inhibitor is 0.15% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the photocured film is recorded as PU1NVP2.

[0068] Example 6

[0069] The same as Example 1, the only difference is that the mass ratio of PU to NVP is 1:3, and the amount of photoinitiator is 0.5% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, the amount of inhibitor is 0.15% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the photocured film is recorded as PU1NVP3.

[0070] Shape memory demonstration

[0071] The glass transition temperature (Tg) of the sample was measured by DMA (242°C) and the range of the glass transition temperature (Tg) was -22.5 to 113.8°C. Figure 1 ), where the oral temperature (36.3-37.5°C) is within the above range, Figure 2 The figure is a bar graph of the glass transition temperature of the material prepared in the present invention, which illustrates that the material of the present invention can produce shape memory effect at oral temperature.

[0072] The materials prepared in Examples 1 to 6 were subjected to a thermal response shape memory demonstration, and the selected temperature was 37°C. Figure 3 As shown, it can be seen that the material has a shape memory effect. The sample strip of the embodiment is folded in hot water at 70-80°C, fixed to a temporary shape in ice water at 0°C, and then placed in an oven at 37°C. It can be seen that the shape of the sample strip slowly recovers, and the shape recovery rate can reach 80% within 4 days.

[0073] Mechanical properties

[0074] The mechanical properties of the materials prepared in the examples were tested at room temperature using a Shimadzu AG-X (5000N) electronic universal testing machine. The tensile speed was 1 mm / min. The sample shape was cut into a dumbbell shape according to the international standard ISO-527-2 / 5B. The average value of three test strips was taken. The yield stress of Examples 5 and 6 was measured to be greater than 30 MPa, the yield strain was greater than 4%, and the elastic modulus was greater than 1500 MPa, which met the industry standard for tensile properties in "Diaphragms for Orthodontic Appliances in Dentistry" (YY / T 1819-2022). See for details. Figure 4 As shown, Figure 4 The picture on the right side is a partial enlarged picture.

[0075] 4D Printing

[0076] The invisible braces are modeled by computer modeling software (4DMAX, CAD, Solidworks, Blender and other three-dimensional modeling software), and then sliced ​​using slicing software. The material of Example 5 was selected for digital light processing (DLP) and stereolithography (SLA). The program used for 4D printing of the material was 350-400nm wavelength ultraviolet light irradiation for 10s / layer, and the printing chamber temperature was 60°C. The 4D printing effect diagram is as follows Figure 5 As shown, it can be seen that the printed invisible braces have a certain degree of precision.

[0077] In summary, the materials of Examples 1 to 6 meet the requirements for being materials for invisible braces with shape memory properties, and Example 5 meets the industry standard requirements for orthodontic appliance diaphragms.

[0078] Comparative Example

[0079] Commonly used invisible braces materials on the market were used as comparison examples (the hard version of Angelalign was comparison example 1, the soft version of Angelalign was comparison example 2, and Invisalign was comparison example 3). After being cut into samples, differential scanning calorimetry (DSC) testing was performed.

[0080] The glass transition temperature of the comparative example was measured using DSC STA449F3 (NETZSCH, Germany). The test was carried out under a nitrogen atmosphere. The DSC test followed the following procedure: the sample was heated from room temperature to 100°C to eliminate the influence of thermal history. Subsequently, the sample was cooled to -100°C and then heated to 100°C. The heating / cooling rate of the whole process was set to 10°C / min. The second heating stage was used to evaluate the glass transition temperature of the material.

[0081] Figure 6 It is the DSC curve diagram of the comparative example.

[0082] Table 1 shows the specific data of the glass transition temperature of the embodiments and comparative examples. It can be seen that the invisible orthodontic appliance material designed by the present invention can produce a shape memory effect within the oral temperature range (36.3-37.5°C). The polymer of the present invention is a thermally responsive shape memory polymer, which is composed of a reversible phase and a stationary phase. The stationary phase plays a role in maintaining the original shape, which is generally undertaken by the physical crosslinking points or chemical crosslinking points in the material. The reversible phase plays a role in maintaining the temporary shape, which is undertaken by the melting-crystallization or amorphous-vitrification process of the chain segments in the polymer. When heated to the melting point or glass transition temperature of the reversible phase, the reversible phase segments can move freely and can be shaped at this time. Then, the molecular chain is crystallized or vitrified by cooling to fix the reversible phase to obtain a temporary shape. When the temperature is raised again to exceed the melting point or glass transition temperature of the reversible phase, it is driven by entropy change, and the segments move freely again and tend to return to the free state and the material returns to the original shape. The melting point of the reversible phase of the polyurethane-based thermally responsive shape memory polymer of the present invention is located in the oral temperature range or its glass transition temperature includes the oral temperature range.

[0083] Table 1 Glass transition temperature of Examples and Comparative Examples

[0084] Glass transition temperature / ℃ Is it within the oral temperature range? Comparative Example 1 95.76 no Comparative Example 2 85.92 no Comparative Example 3 112.91 no Glass transition zone / ℃ Is it within the oral temperature range? Example 1 -15.6～64.1 yes Example 2 -15.5～71.4 yes Example 3 -22.5～84.3 yes Example 4 -7.3～100 yes Example 5 -5.4～113.8 yes Example 6 -7.6～109.2 yes

[0085] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A 4D printed invisible brace material based on shape memory polymer, characterized in that: The invention is prepared from the following raw materials in parts by weight: 100-500 parts of polyester polyol, 400-800 parts of isocyanate, 400-800 parts of chain extender, 200-4800 parts of 1-vinyl-2-pyrrolidone, 5-35 parts of photoinitiator and 1-15 parts of polymerization inhibitor.

2. The 4D printed invisible brace material according to claim 1, characterized in that: The polyester polyol includes polyethylene terephthalate-1,4-cyclohexanedimethanol and / or polycarbonate diol.

3. The 4D printing invisible orthodontic appliance material according to claim 1 or 2, characterized in that: The number average molecular weight of the polycarbonate diol is 1000-2000.

4. The 4D printing invisible brace material according to claim 1, characterized in that: The chain extender includes hydroxyethyl methacrylate and / or dimethylaminoethyl methacrylate.

5. The method for preparing a 4D printed invisible orthodontic appliance material based on a shape memory polymer according to any one of claims 1 to 4, characterized in that: The following steps are involved: The polyester polyol, isocyanate and chain extender are mixed to carry out prepolymerization reaction to obtain a polyurethane prepolymer; The polyurethane prepolymer, 1-vinyl-2-pyrrolidone, a photoinitiator and an inhibitor are mixed to obtain the 4D printing invisible orthodontic appliance material based on the shape memory polymer.

6. The preparation method according to claim 5, characterized in that: The mass ratio of the polyurethane prepolymer to 1-vinyl-2-pyrrolidone is 1-3:3-1.

7. The preparation method according to claim 5, characterized in that: The prepolymerization reaction temperature is 60-80° C. and the reaction time is 2-3 hours.

8. Use of the 4D printing invisible braces material based on shape memory polymer according to any one of claims 1 to 4 or the 4D printing invisible braces material based on shape memory polymer obtained by the preparation method according to any one of claims 5 to 7 in the preparation of oral invisible braces.

9. A 4D printed invisible brace appliance, characterized in that: The 4D printing invisible braces material based on shape memory polymer according to any one of claims 1 to 4 or the 4D printing invisible braces material based on shape memory polymer obtained by the preparation method according to any one of claims 5 to 7 is obtained by 4D printing.

10. The 4D printed invisible braces according to claim 9, characterized in that: The parameters of the 4D printing include: ultraviolet light wavelength of 350-400 nm, irradiation time of 10-30 s / layer, and printing temperature of 20-60° C.

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