Stress relaxation resistant TPU material multilayer dental diaphragm and preparation method thereof

Abstract

The present invention belongs to the field of biomedical science and technology, and specifically discloses a multilayer dental diaphragm made of TPU material for stress relaxation resistance and a preparation method thereof, comprising a three-layer TPU material diaphragm, wherein the first and third layers are both high-relaxation performance TPU materials, and the second layer is low-flexural modulus TPU material. Through photocuring and crosslinking, chemical bonds are formed between the three diaphragm layers. The high-relaxation performance TPU outer layer provides the correction force required for the diaphragm, and the low-flexural modulus TPU inner layer produces a certain buffering effect to prevent excessive initial correction force from causing discomfort to the patient, taking into account both correction effect and comfort. The three-layer dental diaphragm is prepared with these two materials, and then through photocuring and crosslinking, chemical bonds are formed between the three diaphragm layers to ensure that the multilayer diaphragm retains better relaxation performance while greatly improving the patient's wearing comfort. By changing the content of TMPME in the inner and outer layers, the crosslinking density can be changed, thereby achieving a gradient change in diaphragm performance to meet the different strengths of correction force and relaxation effect required for orthodontics.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical science and technology, and specifically discloses a multi-layer dental diaphragm made of TPU material for stress relaxation resistance and a preparation method thereof. Background Art

[0002] At present, with the improvement of people's aesthetic taste, more and more patients with malocclusion are beginning to seek orthodontic treatment. For orthodontic treatment, people need to avoid affecting their normal life as much as possible without affecting their aesthetic appearance. As an auxiliary treatment, orthodontic treatment can adjust the coordination between the facial bones, teeth, and maxillofacial nerves and muscles, making it easier for patients to eat and drink; at the same time, it can also make the patient's oral and maxillofacial system more balanced and beautiful. In recent years, the social recognition of removable bracketless invisible braces has gradually increased. Invisible braces have controllable efficacy, are comfortable and beautiful to wear, and the correction force and treatment period can be controlled to a certain extent. Therefore, they are widely accepted by doctors and patients. The invisible braces market has an annual growth of 40%. However, invisible braces have certain problems: for example, the correction force is lower than that of bracket straight wire braces, and the correction effect is poor for cases such as large incisor movement. In addition, removable bracketless invisible braces usually have high stress attenuation, which may lead to a longer correction period.

[0003] To solve the stress relaxation problem, patent application number 202210798699.5 provides a process for preparing a multilayer diaphragm. This process greatly improves the relaxation performance of the diaphragm through the multilayer structure of the diaphragm, allowing the diaphragm to withstand long-term use and still maintain a high correction force. However, compared with a single-layer diaphragm, this multilayer diaphragm causes the correction force to be reduced to varying degrees. Patent application number CN 113773462 A provides a method for preparing a polyurethane diaphragm for invisible orthodontics. This patent uses in-situ polymerization technology to dope nanohydroxyapatite into the formed polyurethane elastomer, and utilizes the covalent bond density between nanohydroxyapatite and the polymer material and its own physical cross-linking effect to improve the strength and rebound rate of the material. The TPU diaphragm obtained by this method can adjust the maximum correction force, but the stress relaxation performance is still defective, and the correction force is greatly attenuated in a relatively short period of time. Summary of the Invention

[0004] In order to solve the problems in the background technology, the present invention discloses a multi-layer dental diaphragm made of TPU material for stress relaxation, including a three-layer TPU material diaphragm, the outer layer is a high-relaxation performance TPU material, and the inner layer is a low-bending modulus TPU material. The high-relaxation performance TPU outer layer provides the corrective force required for the diaphragm, and the low-relaxation performance TPU inner layer produces a certain buffering effect to prevent excessive initial corrective force from causing discomfort to the patient. It can take into account both the corrective effect and comfort, and meet the different intensities of corrective force and relaxation effect required for orthodontics.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] The multi-layer dental diaphragm made of TPU material for stress relaxation resistance includes three layers of TPU material diaphragms, which are the first layer, the second layer and the third layer arranged in sequence. The first layer and the third layer are both high relaxation performance TPU materials, and the second layer is a low bending modulus TPU material. Through photocuring cross-linking, chemical bonds are formed between the three layers of the diaphragm.

[0007] Furthermore, the stress relaxation resistant TPU material multilayer dental diaphragm, the high relaxation performance TPU material has the following components:

[0008]

[0009] Furthermore, the ratio of each component of the TPU material multilayer dental diaphragm with low bending modulus is:

[0010]

[0011] The method for preparing a multilayer dental film made of TPU material for stress relaxation resistance comprises the following steps:

[0012] Step c1: preparing a high relaxation performance TPU material and a low flexural modulus TPU material, crushing the obtained two TPU material block materials respectively, and screening the obtained granules using a sieve;

[0013] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU film with a thickness of 0.4-0.75 mm, wherein the thickness ratio of the first layer, the second layer, and the third layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240° C. and 260° C., and the processing temperature of the low flexural modulus TPU material is between 200° C. and 220° C.;

[0014] Step c3: first heating the obtained multilayer film, and irradiating it with UV light to crosslink and solidify the film, and then cooling it to obtain a light-cured, cross-linked, stress relaxation-resistant TPU material multilayer dental film.

[0015] Furthermore, the method for preparing the stress relaxation resistant TPU material multilayer dental membrane and the method for preparing the high relaxation performance TPU material are as follows:

[0016] Step a1, prepolymerization: mixing the dried oligomer diol and trimethylolpropane monoallyl ether with diisocyanate, antioxidant and catalyst, introducing nitrogen, and stirring to react at 80-100 degrees;

[0017] Step a2, chain extension: heating the prepolymer system to 120-150° C., adding dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0018] Step a3, cooling, molding and crushing: The polyurethane material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a granular high-relaxation performance TPU product.

[0019] Furthermore, the method for preparing the stress relaxation resistant TPU material multilayer dental membrane and the method for preparing the low flexural modulus TPU material are as follows:

[0020] Step b1, prepolymerization: after drying, the oligomer diol and trimethylolpropane monoallyl ether are mixed with diisocyanate, antioxidant and catalyst, nitrogen is introduced, and stirring reaction is carried out at 80-100 degrees;

[0021] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried small molecule diol to the prepolymer to react and obtain polyurethane;

[0022] Step b3, cooling, forming and crushing: The polyurethane material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0023] Furthermore, in the method for preparing a multilayer dental film made of TPU material for stress relaxation resistance, in step c3, the obtained product is heated to 90 degrees Celsius, and then irradiated with ultraviolet light with a wavelength of 365nm, an irradiation time of 7 seconds, and an exposure energy of 600mJ / cm2 for photocuring and cross-linking, and cooled to obtain a photocured and cross-linked multilayer dental film made of TPU material for stress relaxation resistance.

[0024] Furthermore, in the method for preparing a multilayer dental film made of TPU material for stress relaxation resistance, the oligomer diol refers to a mixture of one or more of polybutylene adipate diol, polyε-caprolactone diol, and polytetramethylene glycol, and has a number average molecular weight of 500-2000.

[0025] Furthermore, in the method for preparing the stress relaxation resistant TPU material multilayer dental membrane, the diisocyanate is a mixture of one or more of IPDI, MDI, and HDI.

[0026] Furthermore, in the method for preparing the stress relaxation resistant TPU material multilayer dental film, the small molecule diol is a mixture of one or more of 1,4-butanediol, 1,6-hexanediol and 1,4-cyclohexanedimethanol.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention discloses a multilayer dental diaphragm made of TPU material for stress relaxation, comprising a three-layer TPU material diaphragm, an outer layer of which is a high-crosslinked multilayer diaphragm made of TPU material, the high-relaxation performance TPU outer layer provides the correction force required by the diaphragm, and an inner layer is a low-bending modulus TPU material, the low-bending modulus TPU inner layer produces a certain buffering effect, thereby preventing excessive initial correction force from causing discomfort to patients, and can take into account both correction effect and comfort. The three-layer dental diaphragm is prepared with these two materials, and then light-cured cross-linking is performed to form chemical bonds between the three layers of the diaphragm, thereby ensuring that the multilayer diaphragm retains better relaxation performance while greatly improving the wearing comfort of the patient. By changing the content of TMPME in the inner and outer layers, the cross-linking density can be changed, thereby achieving a gradient change in the diaphragm performance to meet the different strengths of correction force and relaxation effect required for orthodontics. DETAILED DESCRIPTION

[0029] In order to make the technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1

[0031] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0032]

[0033] Preparation method of outer layer high relaxation performance TPU material:

[0034] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether, 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0035] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0036] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0037] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0038]

[0039] The preparation method of the inner layer low bending modulus TPU material comprises:

[0040] Step b1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0041] Step b2, chain extension: the system is heated to 120-150°C, and dried 1,6-hexanediol is added to the prepolymer to react and obtain polyurethane;

[0042] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0043] Here, it should be noted that in the prepolymerization reactions in steps a1 and b1 of the present invention, the antioxidant is one or two or more of 1010, 1076, 1098 or 168 antioxidants, and the catalyst is any one or a mixture of two of stannous octoate or an amine catalyst. Different antioxidants and catalysts have little effect on the experimental results. Therefore, in other embodiments and comparative examples other than Example 1, the antioxidant is 1010 antioxidant and the catalyst is stannous octoate catalyst as an example for illustration.

[0044] Preparation method of three-layer TPU dental diaphragm:

[0045] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0046] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0047] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm2 .

[0048] Example 2

[0049] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0050]

[0051] Preparation method of outer layer high relaxation performance TPU material:

[0052] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0053] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0054] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0055] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0056]

[0057] The preparation method of the inner layer low bending modulus TPU material comprises:

[0058] Step b1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours.

[0059] Step b2, chain extension: the system is heated to 120-150°C, and dried 1,6-hexanediol is added to the prepolymer to react and obtain polyurethane;

[0060] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0061] Preparation method of three-layer TPU dental diaphragm:

[0062] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0063] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0064] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0065] Example 3

[0066] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0067]

[0068] Preparation method of outer layer high relaxation performance TPU material:

[0069] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0070] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0071] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0072] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0073]

[0074]

[0075] The preparation method of the inner layer low bending modulus TPU material comprises:

[0076] Step b1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0077] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried 1,6-hexanediol to the prepolymer to react and obtain polyurethane;

[0078] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0079] Preparation method of three-layer TPU dental diaphragm:

[0080] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0081] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0082] Step c3: irradiate the multilayer film obtained in step c2 with UV light to crosslink and cure the film. The UV light wavelength is 365 nm, the irradiation time is 7 seconds, and the exposure energy is 600 mJ / cm 2 .

[0083] Example 4

[0084] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0085]

[0086] Preparation method of outer layer high relaxation performance TPU material:

[0087] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0088] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0089] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0090] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0091]

[0092] The preparation method of the inner layer low bending modulus TPU material comprises:

[0093] Step b1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0094] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried 1,6-hexanediol to the prepolymer to react and obtain polyurethane;

[0095] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0096] Preparation method of three-layer TPU dental diaphragm:

[0097] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0098] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0099] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0100] Example 5

[0101] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0102]

[0103]

[0104] Preparation method of outer layer high relaxation performance TPU material:

[0105] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, and then isophorone diisocyanate (IPDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst are mixed, nitrogen is introduced, and the mixture is stirred and reacted at 80-100 degrees for 3 hours;

[0106] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0107] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0108] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0109]

[0110] The preparation method of the inner layer low bending modulus TPU material comprises:

[0111] Step b1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing isophorone diisocyanate (IPDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0112] Step b2, chain extension: the system is heated to 120-150°C, and dried 1,6-hexanediol is added to the prepolymer to react and obtain polyurethane;

[0113] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0114] Preparation method of three-layer TPU dental diaphragm:

[0115] Step c1, crushing the high relaxation performance TPU product and the low flexural modulus TPU product block products prepared according to the above preparation method, and screening the obtained pellets using a sieve;

[0116] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0117] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0118] Example 6

[0119] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0120]

[0121] Preparation method of outer layer high relaxation performance TPU material:

[0122] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing hexamethylene diisocyanate (HDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0123] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0124] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0125] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0126]

[0127] The preparation method of the inner layer low bending modulus TPU material comprises:

[0128] Step b1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, and then hexamethylene diisocyanate (HDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst are mixed, nitrogen is introduced, and the mixture is stirred and reacted at 80-100 degrees for 3 hours.

[0129] Step b2, chain extension: the system is heated to 120-150°C, and dried 1,6-hexanediol is added to the prepolymer to react and obtain polyurethane;

[0130] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0131] Preparation method of three-layer TPU dental diaphragm:

[0132] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0133] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0134] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0135] Example 7

[0136] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0137]

[0138] Preparation method of outer layer high relaxation performance TPU material:

[0139] Step a1, prepolymerization: poly-ε-caprolactone diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) were dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), poly-ε-caprolactone diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0140] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0141] Step a3, cooling, forming and crushing: Cool the material obtained in step a2 to obtain a block product, and then crush the block product into a crusher to obtain a crushed granular high relaxation performance TPU product.

[0142] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0143]

[0144]

[0145] The preparation method of the inner layer low bending modulus TPU material comprises:

[0146] Step b1, prepolymerization: poly-ε-caprolactone diol and trimethylolpropane monoallyl ether (TMPME) were dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), poly-ε-caprolactone diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0147] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried 1,6-hexanediol to the prepolymer to react and obtain polyurethane;

[0148] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0149] Preparation method of three-layer TPU dental diaphragm:

[0150] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0151] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0152] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0153] Example 8

[0154] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0155]

[0156] Preparation method of outer layer high relaxation performance TPU material:

[0157] Step a1, prepolymerization: Tetrahydrofuran diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polytetrahydrofuran diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0158] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0159] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0160] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0161]

[0162] The preparation method of the inner layer low bending modulus TPU material comprises:

[0163] Step b1, prepolymerization: polytetrahydrofuran diol and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polytetrahydrofuran diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring the reaction at 80-100 degrees for 3 hours;

[0164] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried 1,6-hexanediol to the prepolymer to react and obtain polyurethane;

[0165] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0166] Preparation method of three-layer TPU dental diaphragm:

[0167] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0168] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; wherein the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0169] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0170] Example 9

[0171] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0172]

[0173] Preparation method of outer layer high relaxation performance TPU material:

[0174] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0175] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0176] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0177] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0178]

[0179] The preparation method of the inner layer low bending modulus TPU material comprises:

[0180] Step b1, prepolymerization: polybutylene adipate diol and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0181] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried 1,4-butanediol to the prepolymer to react and obtain polyurethane;

[0182] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0183] Preparation method of three-layer TPU dental diaphragm:

[0184] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0185] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; wherein the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0186] Step c3: irradiate the multilayer film obtained in step 3 with UV light to crosslink and cure the film. The UV light wavelength is 365 nm, the irradiation time is 7 seconds, and the exposure energy is 600 mJ / cm 2 .

[0187] Example 10

[0188] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0189]

[0190] Preparation method of outer layer high relaxation performance TPU material:

[0191] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0192] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120°C to 150°C for 2 to 3 hours, heating the prepolymer system to 120-150°C, adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0193] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0194] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0195]

[0196] The preparation method of the inner layer low bending modulus TPU material comprises:

[0197] Step b1, prepolymerization: polybutylene adipate diol and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0198] Step b2, chain extension: heating the system to 120-150°C, adding dried 1,4-cyclohexanedimethanol to the prepolymer to react and obtain polyurethane;

[0199] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0200] Preparation method of three-layer TPU dental diaphragm:

[0201] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0202] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0203] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0204] Example 11

[0205] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0206]

[0207] Preparation method of outer layer high relaxation performance TPU material:

[0208] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0209] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0210] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0211] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0212]

[0213] The preparation method of the inner layer low bending modulus TPU material comprises:

[0214] Step b1, prepolymerization: polybutylene adipate diol and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring the reaction at 80-100 degrees for 3 hours.

[0215] Step b2, chain extension: the system is heated to 120-150°C, and dried 1,6-hexanediol is added to the prepolymer to react and obtain polyurethane;

[0216] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

[0217] Preparation method of three-layer TPU dental diaphragm:

[0218] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0219] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm; the ratio of each layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C.

[0220] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0221] Comparative Example 1

[0222] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0223]

[0224] Preparation method of outer layer high relaxation performance TPU material:

[0225] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) is dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring the mixture at 80-100 degrees for 3 hours;

[0226] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0227] Step a3, cooling, forming and crushing: the material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product.

[0228] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0229]

[0230] The preparation method of the inner layer low bending modulus TPU material comprises:

[0231] Step b1, prepolymerization: polybutylene adipate diol and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours.

[0232] Step b2, chain extension: the system is heated to 120-150°C, and dried 1,6-hexanediol is added to the prepolymer to react and obtain polyurethane;

[0233] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product.

[0234] Preparation method of three-layer TPU dental diaphragm:

[0235] Step c1, crushing the two TPU block products prepared according to the above preparation method, and screening the obtained pellets using a sieve;

[0236] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU film with a thickness of 0.4-0.75 mm; wherein the ratio of each layer is 3:4:3,

[0237] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0238] Comparative Example 2

[0239] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0240]

[0241] Preparation method of outer layer high relaxation performance TPU material:

[0242] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) and trimethylolpropane monoallyl ether (TMPME) are dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), trimethylolpropane monoallyl ether (TMPME), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0243] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0244] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product with high relaxation performance.

[0245] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0246]

[0247] The preparation method of the inner layer low bending modulus TPU material comprises:

[0248] Step b1, prepolymerization: drying polybutylene adipate diol at 70 degrees for 4 hours, then mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0249] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried 1,6-hexanediol to the prepolymer to react and obtain polyurethane;

[0250] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product.

[0251] Preparation method of three-layer TPU dental diaphragm:

[0252] Step c1, crushing the two TPU block products prepared according to the above preparation method, and screening the obtained pellets using a sieve;

[0253] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU film with a thickness of 0.4-0.75 mm; wherein the ratio of each layer is 3:4:3,

[0254] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0255] Comparative Example 3

[0256] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0257]

[0258] Preparation method of outer layer high relaxation performance TPU material:

[0259] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) is dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring the mixture at 80-100 degrees for 3 hours;

[0260] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0261] Step a3, cooling, forming and crushing: The material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product.

[0262] The mass of each component of the inner layer low flexural modulus TPU material is as follows:

[0263]

[0264] The preparation method of the inner layer low bending modulus TPU material comprises:

[0265] Step b1, prepolymerization: drying polybutylene adipate diol at 70 degrees for 4 hours, then mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0266] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried 1,6-hexanediol to the prepolymer to react and obtain polyurethane;

[0267] Step b3, cooling, forming and crushing: the material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product.

[0268] Preparation method of three-layer TPU dental diaphragm:

[0269] Step c1, crushing the two TPU products prepared according to the above preparation method, and screening the obtained pellets using a sieve;

[0270] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU film with a thickness of 0.4-0.75 mm; wherein the ratio of each layer is 3:4:3,

[0271] Step c3: The multilayer film obtained in step c2 is irradiated with UV light to crosslink and cure the film. The UV wavelength is 365nm, the irradiation time is 7 seconds, and the exposure energy is 600mJ / cm 2 .

[0272] Comparative Example 4

[0273] The mass of each component of the outer layer high relaxation performance TPU material is as follows:

[0274]

[0275]

[0276] Preparation method of high relaxation performance TPU material:

[0277] Step a1, prepolymerization: polybutylene adipate diol (Mn=1000) is dried at 70 degrees for 4 hours, followed by mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring the mixture at 80-100 degrees for 3 hours;

[0278] Step a2, chain extension: drying 2,2,4,4-tetramethyl-1,3-cyclobutanediol at 120° C. to 150° C. for 2 to 3 hours, heating the prepolymer system to 120-150° C., adding the dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane;

[0279] Step a3, cooling, forming and crushing: the material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product.

[0280] Preparation method of TPU dental diaphragm:

[0281] Step c1, crushing the bulk material prepared by the above preparation method, and screening the obtained granules using a sieve;

[0282] Step c2: the crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a TPU film with a thickness of 0.4-0.75 mm;

[0283] Comparative Example 5

[0284] The mass of each component of low flexural modulus TPU material is as follows:

[0285]

[0286] The preparation method of the inner layer low bending modulus TPU material includes:

[0287] Step b1, prepolymerization: drying polybutylene adipate diol at 70 degrees for 4 hours, then mixing diphenylmethane diisocyanate (MDI), polybutylene adipate diol (Mn=1000), 1010 antioxidant and stannous octoate catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees for 3 hours;

[0288] Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried 1,6-hexanediol to the prepolymer to react and obtain polyurethane;

[0289] Step b3, cooling, forming and crushing: The material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular TPU product.

[0290] Preparation method of three-layer TPU dental diaphragm:

[0291] Step c1, crushing the bulk products of the high relaxation performance TPU product and the low flexural modulus TPU product prepared according to the above preparation method, and screening the obtained pellets using a sieve respectively;

[0292] Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU membrane with a thickness of 0.4-0.75 mm.

[0293] Test the tensile mechanical properties of diaphragm materials, including tensile strength, elongation at break, tensile attenuation, flexural modulus and other performance indicators.

[0294] The tensile test refers to the national standard "GB / T1040.3-2006 / ISO527-3:1995 Plastics - Determination of tensile properties - Part 3: Test conditions for film and sheeting".

[0295] The tensile attenuation test refers to the industry standard "YY / T1819-2022: Diaphragms for Orthodontic Appliances in Dentistry".

[0296] The bending test refers to the standard "ASTM D790-2017 Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulation Materials".

[0297] The following are the test results:

[0298]

[0299] Combined with Comparative Examples 4, 5 and other embodiments, it can be considered that when the multilayer diaphragm is compounded, the performance will be neutralized to a certain extent, and the relaxation performance and bending modulus of the composite diaphragm are between the two single-layer diaphragms. Examples 1-4 show that as the content of trimethylolpropane monoallyl ether (TMPME) in the formula increases, the relaxation performance of the diaphragm becomes better. This is because the cross-linking effect of the chemical bond makes it more difficult for the molecular chain of the material to move. Combined with Comparative Example 4 and other embodiments, when the multilayer material is compounded, the bending modulus is greatly reduced, which means that the patient's wearing comfort may be better. Examples 5-11 show that the final performance of the diaphragm is almost unaffected by arbitrarily replacing diisocyanates, small molecule diols, and oligomer diols of the same molecular weight. When high molecular weight oligomers are used to replace raw materials, the relaxation performance of the diaphragm decreases, the bending modulus decreases, and the elongation at break increases. To sum up, the advantage of the composite diaphragm is that it can make up for the shortcomings of the performance of a single diaphragm. In the present invention, the outer layer material with high relaxation performance is compounded with the inner layer material with low bending modulus. The prepared composite diaphragm retains better relaxation performance, while improving the hardness of the diaphragm and improving the wearing comfort of the patient. At the same time, the outer layer material and the inner layer material produce chemical bonds through chemical reactions, rather than thermal bonding at the material level, which further improves the performance of the diaphragm.

[0300] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. The multi-layer dental diaphragm made of TPU material for stress relaxation resistance is characterized by: The invention comprises three layers of TPU material membrane, which are the first layer, the second layer and the third layer arranged in sequence. The first layer and the third layer are both made of high relaxation performance TPU material, and the second layer is made of low bending modulus TPU material. Through light curing and cross-linking, chemical bonds are formed between the three layers of membrane; The proportion of each component of high relaxation performance TPU material is: Diisocyanate 50% to 70%; Oligomeric diol 5% to 10%; 2,2,4,4-tetramethyl-1,3-cyclobutanediol 20% to 40%; Trimethylolpropane monoallyl ether 5% to 15%; Antioxidant 0.1% to 0.8%; Catalyst 0.001%~0.01%; The proportion of each component of low flexural modulus TPU material is: Diisocyanate 50% to 70%; Oligomeric diol 5% to 10%; Small molecule diols 20% to 40%; Trimethylolpropane monoallyl ether 5% to 15%; Antioxidant 0.1% to 0.8%; Catalyst 0.001%~0.01%.

2. The method for preparing a multilayer dental diaphragm made of TPU material for stress relaxation resistance according to claim 1, wherein: The steps include: Step c1: preparing a high relaxation performance TPU material and a low flexural modulus TPU material, crushing the obtained two TPU material block materials respectively, and screening the obtained granules using a sieve; Step c2: The crushed material is extruded using a multi-layer co-extrusion casting machine to prepare a three-layer TPU film with a thickness of 0.4-0.75 mm, wherein the thickness ratio of the first layer, the second layer, and the third layer is 3:4:3, the processing temperature of the high relaxation performance TPU material is between 240°C and 260°C, and the processing temperature of the low flexural modulus TPU material is between 200°C and 220°C; Step c3: first heating the obtained multilayer film, and irradiating it with UV light to crosslink and solidify the film, and then cooling it to obtain a light-cured, cross-linked, stress relaxation-resistant TPU material multilayer dental film.

3. The method for preparing a multilayer dental diaphragm made of TPU material for stress relaxation resistance according to claim 2, wherein: The preparation method of high relaxation performance TPU material is as follows: Step a1, prepolymerization: mixing the dried oligomer diol and trimethylolpropane monoallyl ether with diisocyanate, antioxidant and catalyst, introducing nitrogen, and stirring to react at 80-100 degrees; Step a2, chain extension: heating the prepolymer system to 120-150° C., adding dried 2,2,4,4-tetramethyl-1,3-cyclobutanediol to the prepolymer to react and obtain polyurethane; Step a3, cooling, molding and crushing: The polyurethane material obtained in step a2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a granular high-relaxation performance TPU product.

4. The method for preparing a multilayer dental diaphragm made of TPU material for stress relaxation resistance according to claim 2, wherein: The preparation method of low flexural modulus TPU material is as follows: Step b1, prepolymerization: mixing the dried oligomer diol and trimethylolpropane monoallyl ether with diisocyanate, antioxidant and catalyst, introducing nitrogen, and stirring and reacting at 80-100 degrees; Step b2, chain extension: heating the prepolymer system to 120-150°C, adding dried small molecule diol to the prepolymer to react and obtain polyurethane; Step b3, cooling, forming and crushing: The polyurethane material obtained in step b2 is cooled to obtain a block product, and the block product is crushed by a crusher to obtain a crushed granular low flexural modulus TPU product.

5. The method for preparing a multilayer dental film made of TPU material for stress relaxation resistance according to claim 2, wherein: In step c3, the obtained product is heated to 90 degrees Celsius and then irradiated with ultraviolet light with a wavelength of 365 nm, an irradiation time of 7 seconds, and an exposure energy of 600 mJ / cm 2 , perform photocuring and cross-linking, and cool to obtain a photocuring and cross-linking TPU material multilayer dental membrane for stress relaxation resistance.

6. The method for preparing a multilayer dental diaphragm made of TPU material for stress relaxation resistance according to claim 3 or 4, characterized in that: The oligomer diol refers to a mixture of one or more of polybutylene adipate diol, polyε-caprolactone diol and polytetramethylene glycol, and has a number average molecular weight of 500-2000.

7. The method for preparing a multilayer dental diaphragm made of TPU material for stress relaxation resistance according to claim 3 or 4, characterized in that: The diisocyanate is a mixture of one or more of IPDI, MDI, and HDI.

8. The method for preparing a multi-layer dental diaphragm made of TPU material for stress relaxation resistance according to claim 4, wherein: The small molecule diol is a mixture of one or more of 1,4-butanediol, 1,6-hexanediol and 1,4-cyclohexanedimethanol.

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