CN114590007A

CN114590007A - Layer-by-layer laminated composite diaphragm for invisible orthodontic correction and preparation method and application thereof

Info

Publication number: CN114590007A
Application number: CN202210232639.7A
Authority: CN
Inventors: 丁雪佳; 刘金燕; 李鹏飞; 宋长统; 吴勇振; 李阳
Original assignee: Henan Tuoren Medical Device Co ltd; Beijing University of Chemical Technology
Current assignee: Henan Tuoren Medical Device Co ltd; Beijing University of Chemical Technology
Priority date: 2022-03-09
Filing date: 2022-03-09
Publication date: 2022-06-07

Abstract

The invention relates to a laminated composite diaphragm for invisible orthodontic correction, a preparation method and application thereof, which solve the technical problems of poor transparency, low tensile strength, poor toughness and elasticity, large stress relaxation rate and unsatisfactory treatment effect of the manufactured invisible appliance of the existing invisible orthodontic correction diaphragm, and has a three-layer structure, wherein a thermoplastic polyurethane layer and a polycarbonate layer are respectively arranged on two sides of the invisible orthodontic correction diaphragm; the middle is a nano silicon dioxide modified polyethylene glycol terephthalate-1, 4-cyclohexane dimethanol ester layer. The invention can be used for preparing orthodontic materials.

Description

Layer-by-layer laminated composite diaphragm for invisible orthodontic correction and preparation method and application thereof

Technical Field

The invention relates to a high polymer material and a preparation method thereof, in particular to a layer-by-layer laminated composite diaphragm for invisible orthodontic correction and a preparation method thereof.

Background

The tooth correction is to treat malocclusion deformity through orthodontic or surgical operation, and the malocclusion deformity refers to deformity of teeth, jaw bones and craniofacial surfaces and uneven teeth caused by congenital factors or acquired factors in the growth and development process of children.

The irregular teeth can cause a plurality of problems, firstly, the normal exertion of the oral cavity function is seriously influenced, and the influence is mainly on the chewing, pronunciation, swallowing and breathing functions of people. Secondly, the health and oral hygiene of periodontal tissues are seriously affected, the dentition is irregular, especially the teeth are crowded, on one hand, dental plaque is easy to attach, on the other hand, the teeth are difficult to clean because the toothbrush is difficult to contact, so that the periodontal tissues such as open teeth and alveolar bones are easy to generate inflammation, and symptoms such as swelling in teeth, bleeding, bad breath and the like appear, and if the alveolar bones are seriously affected over time, the teeth can loosen, thereby causing serious consequences. Moreover, the growth and development of the face are seriously influenced, teeth play an extremely important role in the whole growth and development process of the face, and teeth which are normally developed and arranged have the function similar to a bracket for the normal growth of the height, the depth and the width of the face. Finally, the psychological well-being is severely compromised and psychologists indicate that patients with misaligned teeth and malocclusion will be severely compromised by their growth in a jeopardized environment for a long period of time. If not corrected in time, the patient can be burdened with heavy mental burden. The traditional bracket appliance has the problems of poor aesthetic property, easy scratching of the oral cavity, gingival bleeding, improper wearing, improper maintenance of oral cavity sanitation, even gum inflammation, tooth demineralization, color change and the like. The invisible bracket-free appliance is improved aiming at the problems, the invisible appliance is greatly improved to wear beautiful problems, the wearing is more comfortable and convenient, the correction curative effect is intuitive and predictable by combining a digital three-dimensional technology, and simultaneously, the invisible bracket-free appliance gradually permeates orthodontic market along with the change of social and economic structures, so that the invisible bracket-free appliance becomes the trend of orthodontic industry.

The oral orthodontic invisible correction technology is characterized in that a series of continuous correction devices are manufactured by computer three-dimensional reconstruction and auxiliary software design and mechanical equipment, and finally the correction purpose is achieved through continuous small range and periodontal tissue movement, and the technology is considered as a leap of the 21 st century orthodontic clinical correction technology. Compared with the traditional correction technology, the invisible correction technology has the advantages of attractive appearance, comfort, safety, sanitation, cleanness, convenience in wearing and removing, convenience in cleaning, predictable treatment results and the like. Invisible appliances are generally made by heating and softening a transparent polymer film and molding the film on a desired mold under a certain mechanical force or pressure. The hot-pressing membrane is usually made of thermoplastic polymer materials, and the manufactured orthodontic appliance can ensure the orthodontic application effect only by meeting the orthodontic characteristics. The hot-pressing film material for manufacturing bracket-free invisible orthodontic has to meet the following important properties of transparency, mechanical property, thermal property, aging resistance and biocompatibility.

At present, materials used by the invisible orthodontic diaphragm are changed from EVA, PP, PE to PET, PETG to TPU to the current composite membrane material, and the orthodontic device diaphragm material is also continuously upgraded to increase the curative effect and experience of doctors and patients in all aspects.

The Chinese utility model patent application with application number CN200420063272.8 discloses a soft transparent tooth correcting material made of cellulose acetate; chinese patent application No. CN02139224.2 discloses the use of ultra high molecular weight polyethylene for making orthodontic brackets. However, the above two methods have problems that the prepared polymer material has insufficient elastic restoring force, so that the stress generated in the tooth correcting process is insufficient, and the correcting effect is poor.

Chinese patent application No. CN201210129701.6 discloses the use of PETG in combination with TPU and PC as orthodontic material. However, the water absorption and stress relaxation rates of orthodontic materials made from such materials still need to be further reduced.

Chinese patent application publication No. CN105315624A discloses that a blend of PETG, TPU, PC and nano silica is used to make an invisible corrective film by injection molding. However, when the amount of TPU is less than 20%, transparency is ensured, and the flexibility of the material is poor because of the low amount of TPU which is limited by transparency. In addition, the injection molding process requires good material fluidity, so that the sheet material of the blending system has low overall strength, poor resilience and poor invisible correction effect.

In conclusion, the invisible orthodontic membrane prepared by the existing method has poor transparency, low tensile strength, poor toughness and elasticity and large stress relaxation rate, and the prepared invisible orthodontic device has an unsatisfactory treatment effect.

Disclosure of Invention

The invention aims to solve the technical problems of poor transparency, low tensile strength, poor toughness and elasticity and large stress relaxation rate of the existing invisible orthodontic diaphragm and unsatisfactory treatment effect of the manufactured invisible orthodontic device, and provides a layer-by-layer laminated composite diaphragm for invisible orthodontic treatment with high strength, high elasticity, high transparency and low stress relaxation rate and a preparation method thereof.

Therefore, the invention provides a laminated composite diaphragm for invisible orthodontic correction, which is of a three-layer structure, wherein the first layer A is a transparent Thermoplastic Polyurethane (TPU) layer; the second layer is a middle layer B which is a nano-silica modified polyethylene terephthalate-1, 4-cyclohexane dimethanol ester (PETG) layer, and the third layer is an outer layer C which is a Polycarbonate (PC) layer.

Preferably, the outer layer A is a transparent Thermoplastic Polyurethane (TPU) layer with Shore hardness of 75A-82D. In the present invention, component A is a thermoplastic polyurethane elastomer. The TPU has the characteristics of high mechanical property, good elasticity, wear resistance, oil resistance, cold resistance, radiation resistance, ozone resistance, dielectric property and the like. The TPU is selected as the outer layer material of the composite membrane, so that the mechanical property, the elastic property and the like of the laminated membrane can be effectively improved. According to the type of long-chain diol used in the synthesis of TPU, there are polyester type TPU and polyether type TPU. The thermoplastic polyurethane elastomer suitable for use in the present invention includes both a polyester type thermoplastic polyurethane elastomer and a polyether type thermoplastic polyurethane elastomer, but it is preferable to use the polyester type thermoplastic polyurethane elastomer. The invention can obtain products with different hardness by changing the proportion of each reaction component of the TPU, and preferably selects the TPU with Shore hardness of 75A-82D, especially the polyester TPU with the hardness.

For thermoplastic polyurethane elastomers, it can be prepared by methods known in the art, or commercially available, such as DP9665DU, DP9873D, DP3970D, RxT50D, RxT65D,945U, 8798A; TPU from 3D-AID, Taiwan, China; elastollan S375D, S160D, 5778, 58091, 58144, TPU-1195A, SP806, TPU-S90A, ALR, E65D-V, ALRE68D-V from BASF, Germany; lubrizol Estane.2103-75DS, 5778-78D, 8091-70D, 58144-65D, Isoplast.2530, 2510, 2540, 1080AF,1085AF,1095AF,3080AF,3085AF,3090AF of Taiwan great east China; WHT-1264, WHT-1172, WHT-1180, WHT-1185, WHT-1190, and the like, all available from Tantawa corporation. The thermoplastic polyurethane hygiene grades used in the present invention are preferably all medical grade or food grade.

The middle layer B is polyethylene glycol terephthalate-1, 4-cyclohexane dimethanol ester modified by nano silicon dioxide. As for the polyethylene terephthalate-1, 4-cyclohexanedimethanol ester, it can be prepared by a known method in the art, or commercially available, for example, JN100, JN120, JN200, PN200, T95 of the SK group of Korea and BR003, EB062, GN071, 26018, 26006, DA003 of Istman chemical Co., USA, PETG of Biolon Co., USA, etc. As for the modified material nano silica, it can be prepared by a known method in the art, or can be commercially available, and as examples of the nano silica, HN-200, HN-300, HN-380 of the chemical company haoney, seiko, china; w-200, W-150 and BT304 of the Chinese Baote chemical industry Co., Ltd; m-5, LM-150 of Cambot, USA; a200, a300, a380,8106,8202,8972,8974,8812, R812S of degussa germany; v15, N20, T40, H15, H18, H20, H2000 from wacker, germany; QS-102, QS-20, DM-10 of Ribendeshan; HG-NMEYHG and the like of Shanghai Jing sub-nanometer new material company.

In the invention, the average particle size of the nano silicon dioxide is 10-150 nm, preferably 15-100 nm, and more preferably 20-60 nm.

The outer layer material C is Polycarbonate (PC). It can be prepared by methods known in the art or commercially available. Such as Shanghai lithiation M-180R; tabletted K8802, S1003; tableplastic 3015, 3040, 3015; delphinidin K8303; PC-2858, 2405, 2456, 2805 of Bayer AG, Germany; G-3130S, ML3206-ZT/GN-311OP, Japan Imperial corporation; PC-115, 175 and the like of Taiwan Qimei corporation; korea SKM-180R; yanshan petrochemical EPS 30R; k8003 of the Dushan mountain petrochemical industry, etc. The Polycarbonate (PC) used in the present invention is medical grade or food grade.

Preferably, the total thickness of the composite membrane is 0.85-1.05mm, wherein the thickness of the outer layer A is 0.15-0.45 mm, the thickness of the outer layer C is 0.25-0.45 mm, and the balance is the thickness of the middle layer B.

Preferably, the surface layer TPU is transparent polyether type or polyester type thermoplastic polyurethane with Shore hardness of 75A-82D, and the weight average molecular weight of the thermoplastic polyurethane is 80000-180000, preferably 120000-150000.

Preferably, the middle layer is nano-silica modified polyethylene terephthalate-1, 4-cyclohexane dimethanol ester (PETG), and the weight average molecular weight of the PETG is 180000-420000, preferably 220000-300000.

Preferably, the outer layer C is Polycarbonate (PC), and the weight-average molecular weight of the PC is 80000-210000, and preferably 120000-150000.

Preferably, the weight percentage (the same below) of the nano-silica used for modifying the polyethylene terephthalate-1, 4-cyclohexanedimethanol ester (PETG) is controlled to be 0.2-5%, and the content of the nano-silica is preferably 0.5-4%.

Preferably, the light transmittance of the transparent Thermoplastic Polyurethane (TPU), the polyethylene terephthalate-1, 4-cyclohexanedimethanol ester (PETG), and the Polycarbonate (PC) are each independently greater than 82%, preferably 88% to 92%.

The invention also provides a preparation method of the layer-by-layer laminated composite diaphragm invisible orthodontic composite diaphragm, which comprises the following steps:

(a) drying, namely drying the transparent Thermoplastic Polyurethane (TPU) granules at 85 ℃ for 4 hours; drying polyethylene terephthalate-1, 4-cyclohexanedimethanol ester (PETG) pellets for 4 hours at 90 ℃; drying Polycarbonate (PC) at 100 ℃ for 4 hours for later use;

(b) surface treatment of nano silicon dioxide: the surface of the nano silicon dioxide is rich in active alkyl, the specific surface area is large, and the surface energy is high. Advantageously, there is a need to avoid or reduce agglomeration problems and to address compatibility with other materials of the formulation by surface treating the nanosilica. For example, nano silicon dioxide (Si 0)₂) Adding into anhydrous ethanol or toluene, stirring and dispersing for 20min, adding into ethanol or toluene solution containing silane coupling agent (such as KH-550, KH-570, etc.), placing the mixed solution in ultrasonic cleaning machine, ultrasonic treating for 50min, transferring into another container, heating and stirring at 88 deg.C, refluxing for 2.5 hr, vacuum filtering, washing with ethanol or diethyl ether solvent, and drying in vacuum drying oven at 80 deg.C for 4 hr to obtain surface modified nanometer silica (Si 0)₂). The surface energy of the nano silicon dioxide treated in the way is greatly reduced, the agglomeration is obviously reduced, and the compatibility with other components in the orthodontic material is obviously improved;

(c) PETG modification treatment: mixing the surface treated nano silicon dioxide and the dried PETG according to the proportion, setting the temperature of each section of an extruder to be 170 ℃, 190 ℃, 220 ℃, 210 ℃ and 190 ℃, respectively, melting and blending, extruding and granulating, and then drying for 5 hours at the temperature of 100 ℃ for later use;

(d) laminating and tabletting, namely preheating a mould to 130-240 ℃ by using a flat vulcanizing machine, and then sequentially putting the dried materials in the steps (a) - (c) into the mould to laminate layer by layer, wherein the pressure is 4-10 MPa, hot pressing is carried out for 10min, and air is released for 5-8 times in the hot pressing process to avoid generating bubbles; cold pressing for 20min, wherein the cold pressing temperature is 15-25 ℃, and taking out the die from the tablet press after the cold pressing is finished;

(e) demolding: removing the material from the mold;

(f) trimming and heat treatment: and removing the edge of the laminated material by using a cutter, placing the laminated composite material in an oven at 85 ℃ for heat preservation for 2 hours, and naturally cooling to obtain the laminated composite membrane for the invisible orthodontic correction.

The invention also provides application of the laminated composite diaphragm invisible orthodontic composite diaphragm in preparing the tooth socket special for invisible orthodontic correction.

The invention has the following beneficial effects:

the laminated composite diaphragm for invisible correction is of a three-layer structure, and the outer layer material A is transparent thermoplastic polyurethane. The TPU has high mechanical property and good elasticity. The TPU is selected as the outer layer material of the composite membrane, so that the mechanical property, the elastic property and the like of the laminated membrane can be effectively improved; the middle layer material B adopts polyethylene glycol terephthalate-1, 4-cyclohexane dimethanol ester modified by nano silicon dioxide, PETG has high transparency and high strength, and compared with unmodified pure PETG, the stress relaxation rate and the water absorption rate of the modified material are obviously reduced; the outer layer material C polycarbonate is mainly aimed at improving the strength and rigidity of PETG. In summary, the invention adopts the layer-by-layer laminating process technology, and the prepared invisible orthodontic diaphragm has the advantages of good transparency, low stress relaxation rate, good mechanical property and chemical property, and the like, and meets the sanitation level.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1

The embodiment provides a layer-by-layer laminated composite diaphragm for invisible correction, which has a three-layer structure, wherein an outer layer A is TPU-8798A of Germany Bayer company with the thickness of 0.15mm and the hardness of 94A, and an intermediate layer B is a layer-by-layer laminated composite diaphragm with the thickness of 0.4mm and modified by nano silicon dioxidePETG-BR003 from Istman chemical, Nemous, and PC-2858 from Bayer, Germany, with an outer layer C of 0.45mm thickness. The nano silicon dioxide is HG-NMEYHG of Shanghai Huizhi sub-nano new material company, and the specific surface texture thereof is 185m²Per gram, the average grain diameter is 40nm, and the content is more than 99.8 percent.

The preparation method of the layer-by-layer laminated composite membrane for invisible correction comprises the following steps of (a) drying, namely drying TPU-8798A of Germany Bayer company at 85 ℃ for 4 hours for later use, drying PETG-BR003 of American Istmann chemical company at 90 ℃ for 4 hours for later use, and drying PC-2858 of Germany Bayer company at 100 ℃ for 4 hours for later use; (b) surface treatment of nano silicon dioxide: mixing nano silicon dioxide (Si 0)₂) Drying in a vacuum drying oven at 100 deg.C for 2h, adding dried nano-silica into anhydrous ethanol in a three-neck flask, stirring and dispersing for 20min, adding ethanol solution containing 4% silane coupling agent KH-550, subjecting the mixture to ultrasonic treatment in an ultrasonic cleaning machine for 50min, transferring into another three-neck flask, heating and stirring at 88 deg.C, refluxing for 2h, filtering, washing with ethanol, drying in a vacuum drying oven at 80 deg.C for 2h, grinding and sieving. The nano silicon dioxide with the average particle size of 5 nm-60 nm and the surface modification is dried for 2 hours in a vacuum oven at the temperature of 105 ℃ to obtain the nano silicon dioxide after surface treatment and drying. (c) PETG modification treatment: the dried PETG and the dried nano-silica after surface treatment are uniformly mixed according to the proportion of 98/2, the obtained mixture is melted and extruded in a double-screw extruder at the rotating speed of 160rpm and under the multi-stage temperature of 170 ℃, 190 ℃, 220 ℃, 210 ℃ and 190 ℃ along the axial direction of a charging barrel (the temperature is double-screw multi-stage temperature control, wherein the temperature of a charging opening is 170 ℃, and the temperature of a machine head is 190 ℃), and the mixture is granulated. The resulting pellets were dried in a vacuum oven at 80 ℃ for 5h until use. (d) Laminating and tabletting, namely putting the polyester film on the upper inner surface, the lower inner surface and the outer surface of a flat vulcanizing instrument die, putting TPU-8798A between the polyester film layers for pre-hot pressing when the polyester film is preheated to 170 ℃, testing the thickness of the polyester film to be 0.25mm, putting the modified granular material PETG-BR003 on the polyester film layers for hot pressing in the same step, testing the thickness of the film to be 0.75mm, and then putting the outer granular material PC-2858 on the polyester film layers for hot pressingAnd (3) performing pre-hot pressing on the membrane, wherein the steps are the same as the above, finally performing hot pressing for 2min under the pressure of 10MPa, performing air release operation simultaneously, performing air release operation every 10s, releasing gas between materials, and finally performing hot pressing for 10 min. Then, cold pressing the laminated material under a flat vulcanizing instrument under the pressure of 10MPa for 20 min; (e) demolding: taking the material out of the mold, and tearing off the polyester film; (f) trimming and heat treatment: the edges of the laminate were removed with a cutter, and the laminate composite was placed in an oven at 85 ℃ for 2 hours and then allowed to cool naturally.

The obtained dried hot-pressed film was subjected to various performance tests, and the results are shown in table 1.

Example 2

Example 1 was repeated except that the thickness of TPU-8798A in the outer layer was controlled to 0.25mm, the thickness of PETG-BR003 in the intermediate layer was controlled to 0.35mm, and the thickness of PC-2858 in the outer layer was controlled to 0.40 mm.

Example 3

Example 1 was repeated except that the thickness of TPU-8798A in the outer layer was controlled to 0.35mm, that of PETG-BR003 in the intermediate layer was controlled to 0.30mm, and that of PC-2858 in the outer layer was controlled to 0.35 mm.

Example 4

Example 1 was repeated except that the thickness of TPU-8798A in the outer layer was controlled to 0.45mm, that of PETG-BR003 in the intermediate layer to 0.25mm and that of PC-2858 in the outer layer to 0.30 mm.

Example 5

This example provides a specific method of using the present invention as a mouthpiece material. Firstly, the oral environment of a patient is accurately scanned, and an accurate virtual dental model of the patient is obtained. Then, simulating the moving direction and distance of each tooth from the beginning to each stage of finishing correction by a correction engineer and a clinician through digital model software, designing and preparing a virtual correction model of each stage into a photocuring model through a 3D printing technology after the two parties reach a consistence to a simulated correction scheme, then putting the model of each stage into a vacuum hot press and fixing, then putting the diaphragm into vacuum hot press molding equipment, and performing some pretreatment on the diaphragm and the dental model before putting the diaphragm into the vacuum hot press molding equipment. For example, some separating agents are sprayed on the dental model, so that the appliance can be easily taken off from the dental model after preparation is completed, and the surface of the diaphragm needs to be wiped clean in advance before the diaphragm is placed into the hot-press forming equipment, so that impurities are prevented from remaining on the appliance during hot-press forming, and then the initial forming of the appliance can be carried out.

The primarily formed appliance may have sharp edges and the cut surface is rough, so that it is necessary to grind and trim the edge to obtain the final appliance. Firstly, the automatic polishing instrument inputs detailed information of each appliance in advance to ensure that no error of one wire occurs in the whole polishing process. And then correcting the sharp edge, and obtaining the final invisible appliance through artificial fine grinding.

The samples used as comparative examples were dv.d420006 membrane (comparative example 1) and german Erkodur membrane (comparative example 2), respectively, from Biolon, germany.

TABLE 1 Performance parameters for examples 1-4 and comparative examples 1-2

As can be seen from the table 1, the light transmittance of the material prepared in the embodiment is more than 85%, the light transmittance reflects the transparency of the material, the larger the numerical value is, the better the transparency of the material is, and the prepared material meets the transparency requirement of the invisible braces; the mechanical strength is high, and the tooth socket can provide enough force to correct the teeth; the saliva absorption amount is very low, which indicates that the correcting effect cannot be influenced by the swelling deformation of the mouthpiece material due to the saliva absorption during the wearing period of the patient; the stress relaxation rate reflects the stress attenuation speed of the material, the smaller the value of the stress relaxation rate is, the slower the mechanical property attenuation of the surface material is, and the material can be ensured to provide the correction force for a longer time

However, the above description is only exemplary of the present invention, and the scope of the present invention should not be limited thereby, and the replacement of the equivalent components or the equivalent changes and modifications made according to the protection scope of the present invention should be covered by the claims of the present invention.

Claims

1. The laminated composite diaphragm for invisible orthodontic correction is characterized in that the laminated composite diaphragm for invisible orthodontic correction is of a three-layer structure, and a thermoplastic polyurethane layer and a polycarbonate layer are respectively arranged on two sides of the laminated composite diaphragm; the middle is a nano silicon dioxide modified polyethylene glycol terephthalate-1, 4-cyclohexane dimethanol ester layer.

2. The laminated composite diaphragm for invisible orthodontic treatment of the claim 1, wherein the total thickness of the laminated composite diaphragm for invisible orthodontic treatment is 0.85-1.05mm, wherein the thickness of the thermoplastic polyurethane layer is 0.15-0.45 mm, the thickness of the polycarbonate layer is 0.25-0.45 mm, and the balance is the thickness of the nano-silica modified polyethylene terephthalate-1, 4-cyclohexanedimethanol ester layer.

3. The layer-by-layer laminated composite film for invisible orthodontic treatment of claim 1, wherein the thermoplastic polyurethane layer is transparent polyether type or polyester type thermoplastic polyurethane with Shore hardness of 75A-82D, and the weight average molecular weight of the thermoplastic polyurethane layer is 80000-180000.

4. The layer-by-layer laminated composite film for invisible orthodontic treatment of claim 1, wherein the weight average molecular weight of the nano silica modified polyethylene terephthalate-1, 4-cyclohexanedimethanol layer is 180000-420000.

5. The laminated composite film for invisible orthodontic treatment, according to claim 1, is characterized in that the weight average molecular weight of the polycarbonate layer is 80000-210000.

6. The laminated composite film for invisible orthodontic treatment, according to claim 1, is characterized in that the content of the nano silicon dioxide for modifying polyethylene terephthalate-1, 4-cyclohexanedimethanol ester (PETG) is 0.2-5% by weight.

7. The layer-by-layer laminated composite film for invisible orthodontic treatment of claim 1, wherein the light transmittance of the thermoplastic polyurethane layer, the polyethylene terephthalate-1, 4-cyclohexanedimethanol layer and the polycarbonate layer is respectively and independently greater than 82%.

8. The preparation method of the layer-by-layer laminated composite diaphragm invisible orthodontic composite diaphragm for the invisible orthodontic treatment, as claimed in any one of claims 1 to 7, is characterized by comprising the following steps:

(a) drying, namely drying the transparent thermoplastic polyurethane granules, the polyethylene glycol terephthalate-1, 4-cyclohexane dimethanol ester and the polycarbonate respectively for later use;

(b) surface treatment of nano silicon dioxide: adding the nano silicon dioxide into absolute ethyl alcohol or methylbenzene, stirring and dispersing, then adding an ethanol or methylbenzene solution containing a silane coupling agent, then placing the mixed solution into an ultrasonic cleaning machine for ultrasonic treatment, then transferring the mixed solution into another container, heating, stirring, refluxing, carrying out suction filtration, washing with an ethanol or diethyl ether solvent, and drying to obtain surface-modified nano silicon dioxide;

(c) modification treatment of polyethylene terephthalate-1, 4-cyclohexanedimethanol ester: mixing the surface-treated nano silicon dioxide in the step (b) and dried polyethylene glycol terephthalate-1, 4-cyclohexanedimethanol ester PETG in proportion, melting, blending, extruding, granulating and drying for later use;

(d) laminating and tabletting, namely preheating a mould, sequentially putting the dried materials in the steps (a) - (c) into the mould, laminating layer by layer, carrying out hot pressing and cold pressing, and taking out the mould from the tabletting machine after the cold pressing is finished;

(e) demolding: removing the material from the mold;

(f) trimming and heat treatment: and removing the edge of the laminated material by using a cutter, preserving the heat of the laminated composite material, and naturally cooling to obtain the laminated composite diaphragm for the invisible orthodontic correction layer by layer.

9. The application of the laminated composite film for invisible orthodontic treatment in the preparation of the tooth socket special for invisible orthodontic treatment according to the claim 1.