Dental film and appliance

Abstract

The application discloses a dental film and appliance, which comprises a first polymer layer, a second polymer layer and a third polymer layer in sequence; the material of the first polymer layer comprises a polyamide thermoplastic elastomer or a polyurethane elastomer, the material of the second polymer layer comprises a copolyester or a polyamide, and the material of the third polymer layer comprises a polyamide thermoplastic elastomer or a polyurethane elastomer; the hardness of the second polymer layer is 55D-90D; and the thickness ratio of the first polymer layer to the second polymer layer is 1:(0.5-50). The dental film and appliance have the advantages of elastic recovery performance, anti-yellowing performance, anti-staining performance, wear resistance, corrosion resistance and anti-fracture performance.

Description

Technical Field

[0001] This invention relates to a dental membrane and an orthodontic appliance. Background Technology

[0002] Clear aligners are computer-aided removable orthodontic appliances. They consist of a series of flexible, transparent aligners that move teeth gradually and incrementally to achieve orthodontic correction. These aligners are typically made from thermoplastic sheets that are thermoformed, cut, and polished. Wearers usually change their aligners every one or two weeks, and the entire treatment process can last for several months. At different stages of treatment, only some teeth move, while others provide anchorage. Given a specific design, selecting a suitable thermoplastic sheet allows control over the magnitude and duration of the orthodontic force. The speed and effectiveness of treatment largely depend on the performance of the thermoplastic sheet used.

[0003] Orthodontic diaphragms need to have good stress retention properties to provide the force for tooth movement during a 1-2 week wearing period. Simultaneously, the diaphragms should be able to resist occlusal damage and stress cracking to prevent damage and breakage of the orthodontic appliance during wear. Furthermore, for aesthetic purposes, the diaphragms should be able to resist food stains and be easy to clean and disinfect.

[0004] In the prior art, a patent (US10549511B2) from Bay Materials Ltd. discloses a three-layer polymer material with a sandwich structure. The outer layer is a thermoplastic copolyester material, and the middle layer is a thermoplastic polyurethane elastomer. This material is relatively hard and has poor wearing comfort. A patent (US9655691B2) from Invisalign Ltd. discloses a dental appliance with a multi-layer structure, including a rigid copolyester inner layer, first and second soft thermoplastic polyurethane elastomer outer layers, and the rigid inner layer being wrapped by the soft outer layer. This structure uses soft polyurethane as the outer layer that comes into contact with the human body. During use, the outer layer material is prone to damage and staining, affecting both function and aesthetics.

[0005] Currently, there are no dental films or appliances that simultaneously possess excellent elastic recovery properties, anti-yellowing properties, anti-staining properties, wear resistance, corrosion resistance, and fracture resistance. Summary of the Invention

[0006] To address the current lack of dental membranes and orthodontic appliances that simultaneously possess excellent elastic recovery, anti-yellowing, anti-staining, wear resistance, corrosion resistance, and fracture resistance, a dental membrane and orthodontic appliance are provided. This dental membrane and orthodontic appliance offer the advantages of excellent elastic recovery, anti-yellowing, anti-staining, wear resistance, corrosion resistance, and fracture resistance.

[0007] The present invention mainly adopts the following technical solutions to solve the above-mentioned technical problems:

[0008] This invention provides a dental membrane comprising, in sequence, a first polymer layer, a second polymer layer, and a third polymer layer;

[0009] The material of the first polymer layer includes a polyamide-based thermoplastic elastomer or a polyurethane elastomer; the material of the second polymer layer includes a copolyester or a polyamide; and the material of the third polymer layer includes a polyamide-based thermoplastic elastomer or a polyurethane elastomer.

[0010] The hardness of the second polymer layer is 55D-90D;

[0011] The thickness ratio of the first polymer layer to the second polymer layer is 1:(0.5-50).

[0012] In this invention, the hardness of the second polymer layer is preferably 70D-90D, more preferably 75D-85D, for example 75D, 78D, 80D or 83D.

[0013] In this invention, the yield stress of the second polymer layer is preferably 25 MPa or higher, more preferably 40 MPa or higher, for example 44 MPa, 45 MPa, 50 MPa, 52 MPa, or 54 MPa. A yield stress of 40 MPa or higher in the second polymer layer results in better elasticity and fracture resistance of the dental membrane.

[0014] In this invention, the yield strain of the second polymer layer is preferably greater than 4.5%, more preferably greater than 5%, for example 5.3%, 8%, or 10%. A yield strain greater than 5% in the second polymer layer results in better elasticity and fracture resistance of the dental membrane.

[0015] In this invention, the tensile modulus of the second polymer layer is preferably greater than 800 MPa, more preferably 800-3000 MPa, and even more preferably 1000-2000 MPa, for example 1300 MPa, 1400 MPa, 1500 MPa, 1600 MPa, or 1800 MPa. When the tensile modulus of the second polymer layer is within the range of 1000-2000 MPa, the corrective force is moderate, and the garment is comfortable to wear.

[0016] In this invention, the elongation at break of the second polymer layer is preferably greater than 90%, more preferably greater than 100%, for example, 105%, 120%, or 123%. An elongation at break of the second polymer layer greater than 90% is beneficial for improving the fracture resistance of the dental membrane.

[0017] In this invention, preferably, the glass transition temperature of the second polymer layer is 70°C or higher, more preferably 90°C or higher, for example 93°C, 99°C, 103°C, 150°C, 158°C or 163°C.

[0018] In this invention, preferably, the density of the second polymer layer is 0.9 g / cm³. 3 The above is preferably 1 g / cm³. 3 For example, 1.02 g / cm³ 3 1.09 g / cm 3 1.12 g / cm 3 1.15g / cm 3 1.2g / cm 3 Or 1.21 g / cm 3 .

[0019] In some specific embodiments of the present invention, the material of the second polymer layer is a copolyester, and the 24-hour water absorption rate of the second polymer layer is less than 1%, preferably less than 0.5%, for example, 0.2%, 0.3% or 0.35%. When the material of the second polymer layer is a copolyester, its 24-hour water absorption rate of less than 1% is beneficial to reducing the scrap rate of dental membranes.

[0020] In some other specific embodiments of the present invention, the material of the second polymer layer is polyamide, and the 24-hour saturated water absorption rate of the second polymer layer is less than 3.5%, for example, 0.2%, 0.5%, 1.2%, 1.9%, 2.1% or 2.5%. When the material of the second polymer layer is polyamide, its 24-hour water absorption rate of less than 3.5% is beneficial to reducing the scrap rate of dental membranes.

[0021] In this invention, the hardness of the first polymer layer is preferably 60A-75D, more preferably 70A-75D, for example 80A, 85A, 90A, 95A, 45D, or 50D. A hardness of 70A-75D for the first polymer layer provides a soft texture and enhances the wearer's comfort.

[0022] In some specific embodiments of the present invention, the hardness of the first polymer layer is 20D-70D.

[0023] In this invention, the elongation at break of the first polymer layer is preferably greater than 150%, more preferably greater than 200%, for example, 209%, 210%, or 230%. An elongation at break of the first polymer layer greater than 200% can further improve the fracture resistance of the dental membrane.

[0024] In this invention, preferably, the flexural modulus of the first polymer layer is 10-700 MPa, more preferably 10-100 MPa, for example 21 MPa, 31 MPa, 32 MPa, 39 MPa, 45 MPa or 83 MPa.

[0025] In this invention, preferably, the density of the first polymer layer is ≥1 g / cm³. 3 For example, 1.05 g / cm³ 3 1.1g / cm 3 Or 1.2g / cm 3 .

[0026] In this invention, preferably, the melting point of the first polymer layer is greater than 125°C, for example, 135°C, 143°C, 144°C, 145°C, 147°C or 157°C.

[0027] In this invention, preferably, the water absorption rate of the first polymer layer is ≤3.5%, more preferably 1%-3%, for example 1.2%, 1.3%, 1.4%, 1.7%, 1.9%, 2.2% or 2.3%.

[0028] In this invention, the hardness of the third polymer layer is preferably 60A-75D, more preferably 75A-75D, and even more preferably 20D-70D, for example, 80A, 85A, 90A, 95A, 45D, or 50D. A hardness within the above range provides a soft texture and enhances wearer comfort.

[0029] In this invention, the elongation at break of the third polymer layer is preferably greater than 150%, more preferably greater than 200%, for example, 209%, 210%, or 230%. An elongation at break of the third polymer layer greater than 200% can further improve the fracture resistance of the dental membrane.

[0030] In this invention, preferably, the flexural modulus of the third polymer layer is 10-700 MPa, more preferably 10-100 MPa, for example 21 MPa, 31 MPa, 32 MPa, 39 MPa, 45 MPa or 83 MPa.

[0031] In this invention, preferably, the density of the third polymer layer is ≥1 g / cm³. 3 For example, 1.05 g / cm³3 1.1g / cm 3 Or 1.2g / cm 3 .

[0032] In this invention, preferably, the melting point of the third polymer layer is greater than 125°C, for example, 135°C, 143°C, 144°C, 145°C, 147°C or 157°C.

[0033] In this invention, preferably, the water absorption rate of the third polymer layer is ≤3.5%, more preferably 1%-3%, for example 1.2%, 1.3%, 1.4%, 1.7%, 1.9%, 2.2% or 2.3%.

[0034] In some preferred embodiments of the present invention, the first polymer layer and the third polymer layer are made of the same material.

[0035] In this invention, the number-average molecular weight of the polyamide-based thermoplastic elastomer is preferably greater than 5000.

[0036] In this invention, the polyamide-based thermoplastic elastomer is, for example, a polyether-based polyamide thermoplastic elastomer or a polyester-based polyamide thermoplastic elastomer. Specifically, the polyether-based polyamide thermoplastic elastomer is a block polymer comprising polyester soft segments and polyamide hard segments, and the polyester-based polyamide thermoplastic elastomer is a block polymer comprising polyether soft segments and polyamide hard segments.

[0037] In this invention, the thicknesses of the first polymer layer and the second polymer layer are preferably 1:(0.5-10), for example 1:0.9, 1:1, 1:2, 1:2.5, 1:3 or 1:4.

[0038] In this invention, the thickness of the third polymer layer and the second polymer layer is preferably 1:(0.5-50), more preferably 1:(0.5-10), for example 1:0.9, 1:1, 1:2, 1:2.5, 1:3 or 1:4.

[0039] In a specific embodiment of the present invention, the thickness ratio of the first polymer layer, the second polymer layer and the third polymer layer is 1:1:1.

[0040] In some specific embodiments of the present invention, the thickness of the first polymer layer and the third polymer layer are equal.

[0041] In some other specific embodiments of the present invention, the thicknesses of the first polymer layer and the third polymer layer are not equal.

[0042] Preferably, the second polymer layer accounts for 50%-95% of the thickness of the dental membrane.

[0043] In this invention, the thickness of the first polymer layer is preferably 100-300 μm, for example 150 μm, 200 μm, 240 μm or 250 μm.

[0044] In this invention, the thickness of the third polymer layer is preferably 100-300 μm, for example 150 μm, 200 μm, 240 μm or 250 μm.

[0045] In this invention, the thickness of the second polymer layer is preferably 200-600 μm, for example 220 μm, 250 μm, 400 μm or 500 μm.

[0046] In this invention, the thickness of the dental membrane is preferably 400-1500 μm, more preferably 700-1000 μm, for example 750 μm or 900 μm. A thickness in the range of 700-1000 μm can further improve the wear resistance of the dental membrane.

[0047] In this invention, preferably, the tensile modulus of the dental membrane is 800-2500 MPa, more preferably 800-1600 MPa, for example 1076 MPa, 1139 MPa, 1148 MPa, 1210 MPa, 1298 MPa, 1300 MPa or 1448 MPa.

[0048] In this invention, preferably, the yield stress of the dental membrane is greater than 25 MPa, more preferably 30-80 MPa, for example 35 MPa, 38 MPa, 40 MPa, 45 MPa, 50 MPa or 75 MPa.

[0049] In this invention, preferably, the yield strain of the dental membrane is greater than 4%, for example, 4.5%, 4.6%, 5%, 6% or 8%.

[0050] In this invention, preferably, the breaking elongation of the dental membrane is 85% or more, more preferably 90% or more, for example 92%, 100%, 120%, 140%, 150% or 180%.

[0051] In this invention, preferably, the tensile strength of the dental membrane is reduced to less than 70%, more preferably less than 65%, and even more preferably less than 60%, for example, 25%, 45%, 50% or 55%.

[0052] In this invention, preferably, the right-angle tear strength of the dental membrane is 110-220 kN / m, more preferably 110-160 kN / m, for example 114 kN / m, 119 kN / m, 121 kN / m, 130 kN / m or 150 kN / m.

[0053] In some specific embodiments of the present invention, the dental membrane is circular in shape.

[0054] The diameter of the circle is preferably 110-130 mm.

[0055] In some other specific embodiments of the present invention, the dental membrane is rectangular in shape.

[0056] The side length of the rectangle is preferably 110-130mm.

[0057] The method for preparing the dental membrane includes the following steps: the materials of the first polymer layer, the second polymer layer, and the third polymer layer are melt-co-extruded to obtain the dental membrane.

[0058] In this invention, the steps and process parameters of the melt co-extrusion can be conventional in the art.

[0059] In some specific embodiments of the present invention, the water content of the material of the first polymer layer is, for example, less than 1.5%, the water content of the material of the second polymer layer is, for example, less than 0.2%, and the water content of the material of the third polymer layer is, for example, less than 1.5%.

[0060] In some specific embodiments of the present invention, the water content of the material of the first polymer layer is, for example, less than 0.1%, the water content of the material of the second polymer layer is, for example, less than 0.1%, and the water content of the material of the third polymer layer is, for example, less than 0.1%.

[0061] In some specific embodiments of the present invention, the water content of the material of the first polymer layer is, for example, less than 0.04%, the water content of the material of the second polymer layer is, for example, less than 0.04%, and the water content of the material of the third polymer layer is, for example, less than 0.04%.

[0062] In some specific embodiments of the present invention, the melt co-extrusion step includes: extruding the materials of the first polymer layer, the second polymer layer, and the third polymer layer respectively, and then molding them by melt bonding.

[0063] In some specific embodiments of the present invention, the step of cooling and shaping by a shaping roller is further included after the melt co-extrusion.

[0064] The present invention also provides an orthodontic appliance made of the aforementioned dental membrane and conforming to one or more teeth.

[0065] In this invention, the preparation method of the orthodontic appliance includes, for example, the following steps: the above-mentioned dental film is hot-pressed to obtain the orthodontic appliance.

[0066] The temperature of the hot pressing is preferably 170-230°C, for example, 200-220°C.

[0067] The hot pressing time is preferably 18-40s, more preferably 20-40s, and for example 35s.

[0068] Those skilled in the art generally understand that the hot pressing process also includes trimming, grinding, and polishing steps.

[0069] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0070] The reagents and raw materials used in this invention are all commercially available.

[0071] The positive and progressive effects of this invention are as follows:

[0072] The dental membrane of this invention uses a soft polyamide-based thermoplastic elastomer as the surface material and a rigid polyamide or copolyester material as the intermediate layer, which gives the dental membrane and orthodontic appliance excellent elastic recovery properties (i.e., fatigue resistance), anti-yellowing properties (i.e., aging resistance), anti-staining properties (i.e., stain resistance), wear resistance, corrosion resistance, and fracture resistance. At the same time, the orthodontic appliance is soft and comfortable, which can improve wearing comfort, and it is not easy to stain during use and has stable effect. Attached Figure Description

[0073] Figure 1 The diagram shows the structure of the dental membranes prepared in Examples 1-8 and Comparative Examples 1-2.

[0074] Figure 2 The diagram shows the structure of the orthodontic appliances prepared in Examples 1-8 and Comparative Examples 1-2.

[0075] The attached figures are labeled as follows:

[0076] 1-First polymer layer; 2-Second polymer layer; 3-Third polymer layer. Detailed Implementation

[0077] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0078] The raw materials used in Examples 1-8 and Comparative Examples 1 and 2 were sourced from the following sources:

[0079] The polyether-based polyamide thermoplastic elastomer was purchased from Arkema under the trade name Pebax. ® ;

[0080] The polyester-based polyamide thermoplastic elastomer was purchased from Evonik under the trade name VESTAMID. ® ;

[0081] The polyurethane elastomer was purchased from Lubrizol under the trade name Pellaethane. ® ;

[0082] The copolyester was purchased from Eastman under the trade name Tritan Copolyester;

[0083] The polyamide was purchased from Arkema under the trade name Rilsanclear. ® .

[0084] Examples 1-8 and Comparative Examples 1 and 2

[0085] The preparation method of the dental membrane includes the following steps: The materials of the first polymer layer, the second polymer layer, and the third polymer layer are dehumidified and dried until their moisture content is less than 0.1%; then, the materials of the first polymer layer, the second polymer layer, and the third polymer layer are respectively fed into different extruders for extrusion molding, and then melt-bonded to form a multilayer structure material. This multilayer structure material is cooled and shaped to the required thickness by a shaping roller, thus obtaining the dental membrane. The material parameters of each layer in Examples 1-8 and Comparative Examples 1 and 2 are listed in Table 1.

[0086] Schematic diagrams of the dental membranes prepared in Examples 1-8 and Comparative Examples 1-2 are shown below. Figure 1 As shown, each of them sequentially includes a first polymer layer 1, a second polymer layer 2, and a third polymer layer 3; the thickness and hardness of each layer are listed in Table 1.

[0087] The dental films prepared in Examples 1-8 and Comparative Examples 1-2 were thermoformed to conform to the shape of multiple teeth, thus preparing an orthodontic appliance. The thermoforming temperature was 200-220℃, and the thermoforming time was 35 seconds. The structural schematic diagram of the prepared orthodontic appliance is shown below. Figure 2 As shown.

[0088] Table 1

[0089] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Comparative Example 1 Comparative Example 2 Material of the first polymer layer Polyether-based polyamide thermoplastic elastomers Polyether-based polyamide thermoplastic elastomers Polyether-based polyamide thermoplastic elastomers Polyester-based polyamide thermoplastic elastomer polyurethane elastomer polyurethane elastomer Polyether-based polyamide thermoplastic elastomers polyurethane elastomer Polyether-based polyamide thermoplastic elastomers polyurethane elastomer Material of the second polymer layer copolyester copolyester polyamide polyamide copolyester polyamide polyamide polyamide copolyester polyamide Material of the third polymer layer Polyether-based polyamide thermoplastic elastomers Polyether-based polyamide thermoplastic elastomers Polyether-based polyamide thermoplastic elastomers Polyester-based polyamide thermoplastic elastomer polyurethane elastomer polyurethane elastomer Polyether-based polyamide thermoplastic elastomers polyurethane elastomer Polyether-based polyamide thermoplastic elastomers polyurethane elastomer The hardness of the second polymer layer 85D 75D 80D 70D 83D 78D 80D 70D 95D 80D Water absorption rate of the second polymer layer 0.2% 0.35% 1.9% 2.5% 0.3% 2.1% 0.2% 0.5% 0.9% 1.6% Hardness of the first polymer layer 85A 80A 45D 85A 95A 90A 50D 85A 70D 95A Hardness of the third polymer layer 85A 80A 45D 85A 95A 90A 50D 85A 70D 95A Water absorption rate of the first polymer layer 1.2% 1.4% 1.2% 1.3% 1.9% 2.3% 1.7% 2.2% 1.4% 2.2% Water absorption rate of the third polymer layer 1.2% 1.4% 1.2% 1.3% 1.9% 2.3% 1.7% 2.2% 1.4% 2.2% Thickness of the first polymer layer 100um 250um 200um 200um 240um 250um 200um 150um 300um 375um Thickness of the second polymer layer 400um 500um 500um 600um 220um 250um 500um 600um 300um 150um Thickness of the third polymer layer 100um 250um 200um 200um 240um 250um 200um 150um 300um 375um Dental membrane thickness 600um 1000um 900um 1000um 700um 750um 900um 900um 900um 800um

[0090] Example 1

[0091] The first polymer layer, second polymer layer, and third polymer layer prepared in Examples 1-8 and Comparative Examples 1 and 2 were subjected to the following tests:

[0092] 1. Tensile modulus test: The tensile modulus of the second polymer layer was tested in accordance with the standard YY / T 1819-2022.

[0093] 2. Yield stress test: The tensile modulus of the second polymer layer was tested in accordance with the standard YY / T 1819-2022.

[0094] 3. Yield strain test: The yield strain of the second polymer layer was tested in accordance with the standard YY / T 1819-2022.

[0095] 4. Elongation at break test: The elongation at break of the first polymer layer, the second polymer layer and the third polymer layer were tested according to the standard YY / T 1819-2022.

[0096] 5. Glass transition temperature test: The glass transition temperature of the second polymer layer was tested in accordance with the standard ISO 11357-1:2016.

[0097] 6. Density test: The density of the first polymer layer, the second polymer layer and the third polymer layer were tested according to the standard ISO1183-1:2019.

[0098] 7. Flexural modulus test: The elongation at break of the first polymer layer and the third polymer layer were tested according to the standard ISO 178:2019.

[0099] 8. Melting point test: The melting points of the first polymer layer and the third polymer layer were tested according to the standard ISO11357-1:2016.

[0100] The test results are listed in Table 2 below:

[0101] Table 2

[0102] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Tensile modulus (MPa) of the second polymer layer 1800 1400 1500 1300 1600 1400 2100 Yield stress (MPa) of the second polymer layer 54 45 52 50 45 44 20 Yield strain of the second polymer layer 5% 4.5% 10% 8% 5.3% 10% 4.1% Elongation at break of the second polymer layer 90% 100% 105% 120% 95% 123% 131% Glass transition temperature of the second polymer layer (°C) 103 93 163 150 99 158 162 <![CDATA[Density of the second polymer layer (g / cm 3 )]]> 1.21 1.15 1.2 1.12 1.09 1.2 1.10 Elongation at break of the first polymer layer 200% 210% 180% 230% 190% 209% 80% Elongation at break of the third polymer layer 200% 210% 180% 230% 190% 209% 80% Flexural modulus of the first polymer layer (MPa) 31 21 83 32 45 39 145 Flexural modulus of the third polymer layer (MPa) 31 21 83 32 45 39 145 <![CDATA[Density of the first polymer layer (g / cm 3 ).]]> 1.1 1.2 1.2 1.1 1.05 1.05 1.03 <![CDATA[The density of the third polymer layer (g / cm 3 )]]> 1.1 1.2 1.2 1.1 1.05 1.05 1.03 Melting point of the first polymer layer 144 135 147 145 157 143 147 The melting point of the third polymer layer 144 135 147 145 157 143 147

[0103] Example 2

[0104] The dental films prepared in Examples 1-8 and Comparative Examples 1 and 2 were subjected to the following tests:

[0105] 1. The elastic modulus, yield stress, yield strain, elongation at break, tensile attenuation, and right-angle tear strength of dental membranes were tested in accordance with the standard YY / T 1819-2022.

[0106] 2. Stain Resistance Test: Dental membranes were soaked in commonly used colored beverages, such as black tea, coffee, and cola, at 37℃ for 7 days, and the staining was observed. No staining after 7 days at 37℃ indicates excellent stain resistance; partial staining (light staining) indicates good stain resistance; and complete staining (severe staining, dark color) indicates poor stain resistance.

[0107] The test results are listed in Table 3:

[0108] Table 3

[0109] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Comparative Example 1 Tensile modulus (MPa) 1448 1148 1298 1139 1300 1210 2445 1076 2855 Yield stress (MPa) 50 50 45 38 38 40 75 35 62 Yield strain 4.6% 5% 8% 6% 4.5% 5% 6% 4.5% 3.5% Elongation at break 92% 120% 100% 140% 150% 90% 87% 180% 98% Tensile attenuation 45% 50% 50% 60% 45% 25% 70% 55% 60% Right-angle tear strength (kN / m) 130 130 114 119 160 150 220 121 230 Stain resistance excellent excellent excellent excellent good good excellent good excellent

[0110] The dental membrane of this invention has a tensile modulus of 800-2500 MPa, a yield stress greater than 25 MPa, a yield strain greater than 4%, an elongation at break of more than 85%, a tensile attenuation of less than 70%, and a right-angle tear strength of 110-220 kN / m, indicating that it has excellent elastic recovery performance, anti-yellowing performance, anti-staining performance, wear resistance, corrosion resistance, and fracture resistance. At the same time, the orthodontic appliance is soft and comfortable, which can improve the wearing comfort. It is not easy to stain during use and the effect is stable.

[0111] The difference between Example 7 and Example 3 is that Example 3 selected a more suitable hardness for the materials of the first polymer layer and the third polymer layer, that is, the hardness of the materials of the first polymer layer and the third polymer layer is 85A-45D, which can further reduce the tensile modulus of the dental membrane to 800-1600MPa, which can reduce the very strong discomfort caused by the orthodontic appliance made of the dental membrane after wearing it on the human body, improve patient compliance, and thus improve orthodontic efficiency.

[0112] The difference between Example 8 and Example 3 is that the first polymer layer and the third polymer layer in Example 3 are made of polyether-based polyamide thermoplastic elastomer. Compared with polyurethane elastomer, it can reduce the aging and yellowing that may occur during the storage of dental films, thereby reducing the yellowing problem of the orthodontic appliances made from it. At the same time, polyether-based polyamide thermoplastic elastomer can further improve stain resistance and improve the aesthetics of wearing.

[0113] In Examples 1-4, the first and third polymer layers were made of non-polyurethane elastomer materials, which have yellowing resistance and stain resistance properties, and can further improve the dental membrane's aging resistance and stain resistance, and improve the aesthetics of wearing it; in Examples 5-6, the first and third polymer layers were made of polyurethane elastomers, which can further improve the fracture resistance and deformation resistance.

[0114] The second polymer layer of Comparative Example 1 has a hardness of 95D, which is outside the range of 55D-90D. This results in an excessively high tensile modulus of 2855MPa for the dental membrane, which seriously affects the comfort of wearing the orthodontic appliance. The yield stress of the second polymer layer is too low, and the elongation at break of the first and third polymer layers is too low. This makes the dental membrane easy to deform and break when it is made into an orthodontic appliance.

[0115] The thickness ratio of the first polymer layer and the second polymer layer in Comparative Example 2 was too low, not within the range of 1:(0.5-50). When the dental membrane was made into an orthodontic appliance, the appliance was too soft and could not provide sufficient orthodontic force support.

Claims

1. A dental membrane, characterized in that, It comprises, in sequence, a first polymer layer, a second polymer layer, and a third polymer layer; The material of the first polymer layer includes a polyamide-based thermoplastic elastomer or a polyurethane elastomer; the material of the second polymer layer includes a copolyester or a polyamide; and the material of the third polymer layer includes a polyamide-based thermoplastic elastomer or a polyurethane elastomer. The hardness of the second polymer layer is 55D-90D; The thickness ratio of the first polymer layer to the second polymer layer is 1:(0.5-50).

2. The dental membrane as described in claim 1, characterized in that, The hardness of the second polymer layer is 70D-90D, preferably 75D-85D, for example 75D, 78D, 80D or 83D; And / or, the yield stress of the second polymer layer is 25 MPa or more, preferably 40 MPa or more, for example 44 MPa, 45 MPa, 50 MPa, 52 MPa or 54 MPa; And / or, the yield strain of the second polymer layer is greater than 4.5%, preferably greater than 5%, for example 5.3%, 8% or 10%; And / or, the tensile modulus of the second polymer layer is greater than 800 MPa, preferably 800-3000 MPa, more preferably 1000-2000 MPa, for example 1300 MPa, 1400 MPa, 1500 MPa, 1600 MPa or 1800 MPa; And / or, the elongation at break of the second polymer layer is greater than 90%, preferably greater than 100%, for example 105%, 120% or 123%; And / or, the glass transition temperature of the second polymer layer is above 70°C, preferably above 90°C, for example 93°C, 99°C, 103°C, 150°C, 158°C or 163°C; And / or, the density of the second polymer layer is 0.9 g / cm³. 3 The above is preferably 1g / cm³. 3 For example, 1.02 g / cm³ 3 1.09 g / cm 3 1.12 g / cm 3 1.15g / cm 3 1.2g / cm 3 Or 1.21 g / cm 3 ; And / or, when the material of the second polymer layer is copolyester, the 24-hour water absorption rate of the second polymer layer is less than 1%, preferably less than 0.5%, for example, 0.2%, 0.3% or 0.35%; or, when the material of the second polymer layer is polyamide, the 24-hour saturated water absorption rate of the second polymer layer is less than 3.5%, for example, 0.2%, 0.5%, 1.2%, 1.9%, 2.1% or 2.5%.

3. The dental membrane as described in claim 1, characterized in that, The hardness of the first polymer layer is 60A-75D, preferably 70A-75D, for example 80A, 85A, 90A, 95A, 45D or 50D; And / or, the elongation at break of the first polymer layer is greater than 150%, preferably greater than 200%, for example 209%, 210% or 230%; And / or, the flexural modulus of the first polymer layer is 10-700 MPa, preferably 10-100 MPa, for example 21 MPa, 31 MPa, 32 MPa, 39 MPa, 45 MPa or 83 MPa; And / or, the density of the first polymer layer is ≥1 g / cm³. 3 For example, 1.05 g / cm³ 3 1.1g / cm 3 Or 1.2g / cm 3 ; And / or, the melting point of the first polymer layer is greater than 125°C, for example, 135°C, 143°C, 144°C, 145°C, 147°C or 157°C; And / or, the water absorption rate of the first polymer layer is ≤3.5%, preferably 1%-3%, for example 1.2%, 1.3%, 1.4%, 1.7%, 1.9%, 2.2% or 2.3%; And / or, the hardness of the third polymer layer is 60A-75D, preferably 75A-75D, more preferably 20D-70D, for example 80A, 85A, 90A, 95A, 45D or 50D; And / or, the elongation at break of the third polymer layer is greater than 150%, preferably greater than 200%, for example 209%, 210% or 230%; And / or, the flexural modulus of the third polymer layer is 10-700 MPa, preferably 10-100 MPa, for example 21 MPa, 31 MPa, 32 MPa, 39 MPa, 45 MPa or 83 MPa; And / or, the density of the third polymer layer is ≥1 g / cm³. 3 For example, 1.05 g / cm³ 3 1.1g / cm 3 Or 1.2g / cm 3 ; And / or, the melting point of the third polymer layer is greater than 125°C, for example, 135°C, 143°C, 144°C, 145°C, 147°C or 157°C; And / or, the water absorption rate of the third polymer layer is ≤3.5%, preferably 1%-3%, for example 1.2%, 1.3%, 1.4%, 1.7%, 1.9%, 2.2% or 2.3%.

4. The dental membrane as described in claim 1, characterized in that, The thickness ratio of the first polymer layer to the second polymer layer is 1:(0.5-10), for example, 1:0.9, 1:1, 1:2, 1:2.5, 1:3 or 1:4; And / or, the thickness ratio of the third polymer layer to the second polymer layer is 1:(0.5-50), preferably 1:(0.5-10), for example 1:0.9, 1:1, 1:2, 1:2.5, 1:3 or 1:4; And / or, the thickness of the first polymer layer is 100-300 μm, for example, 150 μm, 200 μm, 240 μm or 250 μm; And / or, the thickness of the third polymer layer is 100-300 μm, for example, 150 μm, 200 μm, 240 μm or 250 μm; And / or, the thickness of the second polymer layer is 200-600 μm, for example 220 μm, 250 μm, 400 μm or 500 μm; And / or, the thickness of the dental membrane is 400-1500 μm, preferably 700-1000 μm, for example 750 μm or 900 μm.

5. The dental membrane as described in claim 1, characterized in that, The tensile modulus of the dental membrane is 800-2500 MPa, preferably 800-1600 MPa, for example 1076 MPa, 1139 MPa, 1148 MPa, 1210 MPa, 1298 MPa, 1300 MPa or 1448 MPa. And / or, the yield stress of the dental membrane is greater than 25 MPa, preferably 30-80 MPa, for example 35 MPa, 38 MPa, 40 MPa, 45 MPa, 50 MPa or 75 MPa; And / or, the yield strain of the dental membrane is greater than 4%, for example, 4.5%, 4.6%, 5%, 6% or 8%; And / or, the elongation at break of the dental membrane is 85% or more, preferably 90% or more, for example 92%, 100%, 120%, 140%, 150% or 180%; And / or, the tensile strength of the dental membrane decreases by less than 70%, preferably less than 65%, more preferably less than 60%, for example, 25%, 45%, 50% or 55%; And / or, the right-angle tear strength of the dental membrane is 110-220 kN / m, preferably 110-160 kN / m, for example 114 kN / m, 119 kN / m, 121 kN / m, 130 kN / m or 150 kN / m.

6. The dental membrane as described in claim 1, characterized in that, The first polymer layer and the third polymer layer are made of the same material; And / or, the number-average molecular weight of the polyamide-based thermoplastic elastomer is preferably greater than 5000; And / or, the polyamide-based thermoplastic elastomer is, for example, a polyether-based polyamide thermoplastic elastomer or a polyester-based polyamide thermoplastic elastomer; And / or, the dental membrane is circular in shape; wherein the diameter of the circle is preferably 110-130 mm; or, the dental membrane is rectangular in shape; wherein the side length of the rectangle is preferably 110-130 mm.

7. The dental membrane according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: the materials of the first polymer layer, the second polymer layer, and the third polymer layer are melt co-extruded to obtain a dental film.

8. The dental membrane as described in claim 7, characterized in that, The melt co-extrusion step includes: extruding the materials of the first polymer layer, the second polymer layer, and the third polymer layer respectively, and then molding them by melt bonding; preferably, the melt co-extrusion step further includes a step of cooling and shaping by a shaping roller; And / or, the moisture content of the first polymer layer material is less than 1.5%, the moisture content of the second polymer layer material is less than 0.2%, and the moisture content of the third polymer layer material is less than 1.5%; or, the moisture content of the first polymer layer material is less than 0.1%, the moisture content of the second polymer layer material is less than 0.1%, and the moisture content of the third polymer layer material is less than 0.1%; or, the moisture content of the first polymer layer material is less than 0.04%, the moisture content of the second polymer layer material is less than 0.04%, and the moisture content of the third polymer layer material is less than 0.04%.

9. An orthodontic appliance, characterized in that, It is made of a dental membrane as described in any one of claims 1-8, and conforms to one or more teeth.

10. The orthodontic appliance as claimed in claim 9, characterized in that, The method for preparing the orthodontic appliance includes the following steps: the above-mentioned dental film is hot-pressed to obtain the orthodontic appliance; The temperature of the hot pressing is preferably 170-230°C, for example, 200-220°C; The hot pressing time is preferably 18-40s, more preferably 20-40s, and for example 35s.

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