Multilayer polymer diaphragm and dental appliance

Abstract

The invention discloses a multilayer polymer diaphragm and a dental appliance. The diaphragm comprises an A-layer polymer, a B-layer polymer and a C-layer polymer. Wherein the polymer of the layer A is a high-strength thermoplastic polymer, and the bending elastic modulus of the polymer of the layer A is 1500-2400 MPa; the polymer of the B layer is thermoplastic copolyester with moderate strength, and the bending elastic modulus of the B layer ranges from 1400 MPa to 1800 MPa; and the polymer of the C layer is a thermoplastic elastomer polymer, and the bending elastic modulus is less than or equal to 700MPa. Compared with the prior art, the multi-layer polymer sheet and the dental appliance have better pollution resistance, are flexible and not easy to break, are small in stress attenuation, and are tightly attached to the tooth surface when being worn in the oral cavity. And meanwhile, a comfortable wearing feeling is provided for a user.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a multilayer polymer film and a dental appliance. Background Art

[0002] Invisible braces are removable correction devices made of transparent elastic materials. They achieve the purpose of tooth alignment through continuous small-range tooth movement. At present, the most commonly used diaphragm materials for invisible braces are polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG) and high-hardness polyurethane (TPU, Shore hardness 75-85D). Single-layer diaphragms made of these materials can meet the basic requirements of tooth movement, but there are some shortcomings. For example, single-layer PETG is easy to break under stress, and braces made from it have many cases of breakage in clinical practice. Braces made of high-hardness polyurethane materials are not easy to break, but their stress decay is faster in humid environments. Clinically, it is generally reported that the braces made from them can no longer feel the correction force after being worn in the mouth for 3-5 days. In addition, single-layer diaphragms have a high modulus and poor wearing comfort for patients.

[0003] The ideal brace membrane material should have the following characteristics: (1) The surface is highly wear-resistant and not easy to break; (2) It fits tightly to the tooth surface and provides better mechanical expression; (3) It is stain-resistant and not easy to stain, and is beautiful and hygienic; (4) It has low stress attenuation and provides long-lasting and gentle correction force; (5) It has a moderate elastic modulus and provides a comfortable wearing feeling.

[0004] In order to improve the shortcomings of single-layer materials, a solution of laminating multiple materials has emerged.

[0005] A search of existing patent documents revealed that CN207666718U uses a double-layer structure, with a layer A of hard transparent thermoplastic polyurethane with a Shore hardness of 60D-90D and a soft transparent thermoplastic polyurethane with a Shore hardness of 55A-55D for lamination. This combination improves the disadvantage of a single diaphragm with a high modulus. However, the stress decay of the combined diaphragm is still relatively fast. In addition, when the diaphragm is used to produce an appliance, if the soft polyurethane is facing the tooth model, the layer of soft polyurethane is easily bonded to the tooth model after melting, resulting in the inability to demold. The way to overcome this problem is to spray a layer of release agent on the tooth model in advance. This operation is not only cumbersome, but also causes the release agent to remain on the inner wall of the appliance, thereby creating potential toxicological risks. If the soft polyurethane layer is facing the lip side, the layer is prone to color absorption and odor, affecting the wearing experience. At the same time, this layer of soft layer material is easily worn when the teeth are bitten, causing damage to the appliance, affecting the correction process.

[0006] CN104395379B Multilayer film with improved modulus properties (Bayer) provides a multilayer film having a core layer A, the core layer A comprising at least one polycarbonate or copolycarbonate and / or polyester or copolyester, the glass transition temperature Tg of which is 80°C to 200°C, and the core layer A is located between two outer layers B, the outer layer B comprising at least one thermoplastic polyurethane with a hardness of 45 Shore D to 85 Shore D. Although the polymer sheet described in the patent improves the easy-to-break property of the polyester material, in the process of pressing the orthodontic appliance, the soft layer material is very easy to adhere to the tooth model, which makes demolding difficult; at the same time, the soft material exposed in the outermost layer is easy to absorb color and odor, affecting the wearing experience. In addition, the soft layer material is easy to wear when the teeth are bitten.

[0007] US10549511B2 (Bay) Dual shell dental appliance and material constructions provides a polymer sheet, which adopts a sandwich structure including three layers of A, B, and C, wherein the outer layers A and C are thermoplastic polymers, and the bending elastic modulus thereof ranges from 1000-2500 MPa, and the glass transition temperature or melting point is 80-180°C. The central layer is a thermoplastic polyurethane elastomer, and the bending elastic modulus thereof ranges from 50-500 MPa, and the glass transition temperature or melting point is 90-220°C. The polymer sheet composed of the A layer, the B layer, and the C layer has a total thickness of 250-2000 microns and a bending elastic modulus of 500-1500 MPa. This technology solves the problem of appliance staining, but the rigid material of the outer layer has a poor fit with the teeth, and the polyester material is exposed to the outside, and there is still a possibility of fracture and failure. Summary of the invention

[0008] In order to solve the above problems and provide a better brace diaphragm material, the present invention provides a multilayer polymer diaphragm and a dental appliance. In order to meet the functional requirements of the brace diaphragm, the present invention designs a multilayer diaphragm, wherein layer A is polyurethane or polyamide, layer B is copolyester, and layer C is polyester elastomer material or polyether polyamide elastomer, so as to improve the problem of fitting with the tooth surface. The multilayer diaphragm of the present invention has the characteristics of anti-staining, anti-fracture and high stress retention. When the brace made of the multilayer diaphragm is worn in the oral cavity, layer A faces the lip side and layer C faces the tooth surface.

[0009] Specifically, the purpose of the present invention is achieved through the following technical solutions:

[0010] The present invention provides a multilayer polymer film, comprising a polymer layer A, a polymer layer B and a polymer layer C. The polymer layer A is a high-strength thermoplastic polymer with a bending elastic modulus of 1500-2400 MPa; the polymer layer B is a medium-strength thermoplastic copolyester with a bending elastic modulus of 1400-1800 MPa; the polymer layer C is a thermoplastic polymer elastomer with a bending elastic modulus of ≤700 MPa. The polymer layer B is located between the polymer layer A and the polymer layer C. Preferably, the modulus of the layer B is ≤ the modulus of the layer A.

[0011] As an embodiment of the present invention, the A layer polymer has at least one of the following technical features:

[0012] A. comprising one or more of polyurethane and polyamide;

[0013] B. The bending elastic modulus ranges from 1500 to 2000 MPa.

[0014] As an embodiment of the present invention, the C-layer polymer has at least one of the following technical features:

[0015] A, is a composition selected from polyester elastomer and polyether polyamide elastomer;

[0016] B. Friction coefficient measured according to ASTM D1894>1.0.

[0017] As an embodiment of the present invention, the C-layer polymer is a polyester elastomer. The polyester elastomer is a polyester ether or a copolyester ether, and its glass transition temperature (Tg) is in the range of -60°C to 0°C.

[0018] As an embodiment of the present invention, the polyester elastomer comprises:

[0019] (a) a dicarboxylic acid component comprising 70 wt% to 99 wt% of residues of 1,4-cyclohexanedicarboxylic acid, and 1 wt% to 30 wt% of residues of terephthalic acid, based on 100 wt% of the total acid residues;

[0020] (b) a diol component comprising: i) 70 mol% to 80 mol% of 1,4-cyclohexanedimethanol (CHDM) residues, ii) 10 mol% to 20 mol% of poly(tetramethylene ether) glycol (PTMG) residues, and iii) less than 15 mol% of diol residues other than CHDM and PTMG residues; the mole percentages are based on the total moles of diol residues, with the total moles of diol residues being 100%.

[0021] As an embodiment of the present invention, the lamination is obtained by co-extrusion, and dispenser co-extrusion or in-mold co-extrusion can be selected, and in-mold co-extrusion is preferred.

[0022] As an embodiment of the present invention, the combined thickness of the sheet is 250-2000 microns, wherein the thickness of the polymer layer A accounts for 10-20% of the total thickness, the thickness of the polymer layer B accounts for 60-80% of the total thickness, and the thickness of the polymer layer C accounts for 10-20% of the total thickness.

[0023] The present invention also relates to a dental appliance made of the aforementioned multi-layer polymer film and conforming to one or more teeth.

[0024] As one embodiment of the present invention, the polymer layer C of the multi-layer polymer sheet faces / adheres to the teeth.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) Based on the multilayer polymer film of the present invention, excellent stress retention performance and fracture resistance are shown;

[0027] 2) Based on the multi-layer polymer film of the present invention, better tooth surface fit and wearing comfort can be provided;

[0028] 3) The multilayer polymer film of the present invention exhibits good anti-staining performance. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, some adjustments and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0030] The information of the polymers of the A layer, B layer and C layer of the present invention is shown in Table 1:

[0031] Table 1

[0032]

[0033]

[0034] The compositions of the embodiments and comparative examples are shown in Table 2 below:

[0035] Table 2

[0036]

[0037]

[0038] The performance test results are shown in Table 3:

[0039] Table 3

[0040]

[0041] The yield strain test method refers to the method of GB / T 1040.3-2006 Determination of tensile properties of plastics, and the equipment tensile speed is set to 50mm / min. Type 5 specimens are used.

[0042] The testing method of bending elastic modulus is carried out in accordance with the method specified in GB / T 9341-2008 Determination of flexural properties of plastics.

[0043] The folding endurance test method is carried out in accordance with the method specified in "GB T235-2013 Metal Sheet and Strip Repeated Bending Test Method", and the sample thickness is 0.76mm, width is 25mm, and length is 150mm.

[0044] The puncture resistance test method is carried out in accordance with the method specified in "GB / T 37841-2019 Test method for puncture resistance of plastic film and sheeting". The sample thickness is 0.76mm, the puncture needle diameter is 10±0.05mm, the puncture needle head is hemispherical, the radius is 0.5±0.05mm, and the puncture speed is 200mm / min. The maximum force of the puncture needle vertically penetrating the membrane is the puncture resistance (N).

[0045] The anti-staining performance test method is as follows: soak the sample in coffee at 37°C for 72 hours, and use a 3nhYS3010 spectrophotometer to test the color difference ΔE of the film before and after soaking. The larger the ΔE, the more obvious the color change.

[0046] The stress relaxation test method is: take the tensile elastic modulus test specimen described in this case, stretch it to 101.5% strain, maintain the strain for 24 hours, and record the attenuation curve of the tensile force on the specimen during this period. The test environment is in a 37°C water bath.

[0047] The wear resistance was tested according to the method specified in ASTM F2496-05. A Taber 5900 reciprocating abrader was used, an H18 grinding head was selected (the A side of the diaphragm faced the grinding head), the load was set to 10 Newtons, the reciprocating length was set to 50 mm, the reciprocating speed was set to 60 reciprocations / minute, and the mass loss of the diaphragm after 1000 reciprocations was recorded. The higher the mass loss, the worse the wear resistance.

[0048] In summary, the embodiments of the present invention have a lower stress relaxation rate and better puncture resistance, and are an ideal diaphragm for orthodontic appliances.

[0049] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A multilayer polymer sheet, characterized in that: It comprises a layer A polymer, a layer B polymer and a layer C polymer, wherein the layer B polymer is located between the layer A polymer and the layer C polymer; the layer A polymer is a high-strength thermoplastic polymer with a bending elastic modulus of 1500-2400 MPa; the layer B polymer is a thermoplastic copolyester with a bending elastic modulus ranging from 1400-1800 MPa; the layer C polymer is a thermoplastic elastomer polymer with a bending elastic modulus of ≤700 MPa.

2. The multilayer polymer sheet according to claim 1, characterized in that The A-layer polymer has at least one of the following technical features: A. comprising one or more of polyurethane and polyamide; B. The bending elastic modulus ranges from 1500 to 2000 MPa.

3. The multilayer polymer sheet according to claim 1, characterized in that The C-layer polymer has at least one of the following technical features: A, is a composition selected from polyester elastomer and polyether polyamide elastomer; B. Friction coefficient measured according to ASTM D1894>1.

0.

4. The multilayer polymer sheet according to claim 1, characterized in that The C-layer polymer is a polyester elastomer.

5. The multilayer polymer sheet according to claim 4, characterized in that The polyester elastomer is a polyester ether or a copolyester ether, and its glass transition temperature (Tg) is in the range of -60°C to 0°C.

6. The multilayer polymer sheet according to claim 4, wherein The polyester elastomer comprises: (a) a dicarboxylic acid component comprising 70 wt% to 99 wt% of residues of 1,4-cyclohexanedicarboxylic acid, and 1 wt% to 30 wt% of residues of terephthalic acid, based on 100 wt% of the total acid residues; (b) a diol component comprising: i) 70 mol% to 80 mol% of 1,4-cyclohexanedimethanol (CHDM) residues, ii) 10 mol% to 20 mol% of poly(tetramethylene ether) glycol (PTMG) residues, and iii) less than 15 mol% of diol residues other than CHDM and PTMG residues; the mole percentages are based on the total moles of diol residues, with the total moles of diol residues being 100%.

7. The multilayer polymer sheet according to claim 1, characterized in that The laminate is obtained by co-extrusion lamination, which can be dispenser co-extrusion or in-die co-extrusion, and in-die co-extrusion lamination is preferred.

8. The multilayer polymer sheet according to claim 1, wherein The combined thickness of the sheet is 250 microns to 2000 microns, wherein the thickness of the polymer layer A accounts for 10-20% of the total thickness, the thickness of the polymer layer B accounts for 60-80% of the total thickness, and the thickness of the polymer layer C accounts for 10-20% of the total thickness.

9. A dental appliance made from the multilayer polymer sheet of claim 1, which can conform to one or more teeth.

10. The dental appliance according to claim 9, wherein: The polymer layer C of the multi-layer polymer sheet faces / adheres to the teeth.

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