KR102436487B1 - Method for manufacturing orthodontic multilayer sheet for clear aligner - Google Patents

Abstract

An embodiment of the present invention comprises the steps of (a) mounting the soft thermoplastic polymer material in a roll state to the upper roll and the lower roll of the laminator, respectively, (b) raising the temperature of the upper roll and the lower roll, (c) ) laminating the roll sheets of the soft thermoplastic polymer material mounted on the upper roll and the lower roll in a pressing roll, and (d) laminating the hard thermoplastic polymer material while the soft thermoplastic polymer material is being laminated to the center roll of the laminator It provides a method of manufacturing a multi-layer sheet for transparent correction comprising the step of manufacturing a multi-layer sheet by inserting it into the pressing roll in the process of lamination by mounting to the above.

Description

METHOD FOR MANUFACTURING ORTHODONTIC MULTILAYER SHEET FOR CLEAR ALIGNER

The present invention relates to a method for manufacturing a multi-layered sheet for transparent orthodontics, and more particularly, to a transparent orthodontic material necessary for orthodontic procedures, which is composed of multiple layers to increase orthodontic retention, reduce patient pain, and provide excellent interlayer bonding and durability It relates to a method for manufacturing a transparent orthodontic multi-layer sheet that is configured to have a high stability of the orthodontic device and safety when worn by a patient.

Orthodontic treatment is a therapeutic action applied to treat irregular tooth arrangement or abnormal engagement of upper and lower jaws. In general, treatment is performed using brackets and wires for orthodontic treatment.

Brackets and wires made of In the case of these metal brackets and wires, they are not aesthetically good, and since treatment is carried out by fixing them to the teeth, there is a disadvantage that more attention should be paid to the cleanliness of the oral cavity.

In order to secure these shortcomings, a new orthodontic treatment called transparent orthodontic treatment has recently been progressing a lot around the world. This is an orthodontic appliance using a polymer instead of a conventional metal material. It has the advantage of being transparent and aesthetically excellent, as well as being detachable, so there is no difficulty in oral hygiene management.

The transparent orthodontic device is used for treatment by molding a polymer sheet to suit the patient's oral cavity through vacuum thermoforming. Most of the conventional polymer sheets are composed of polyethylene terephthalate glycol (PETG). Transparent orthodontic devices made of conventional polymer sheets, including PETG, have a characteristic that the pain applied to the patient at the initial stage of wearing the device is great, and the orthodontic force applied to the teeth decreases over time. This causes discomfort and pain to the patient, and gives the teeth a lower orthodontic force unlike the initial one, resulting in tooth movement that does not match the predicted results.

A multi-layer sheet (Polyester-TPU) has been developed to improve this, but there is a disadvantage in that the interlayer bonding strength is weak due to the difference in thermal properties. Due to this, delamination occurs when applying orthodontic products, which causes performance degradation, and the peeled layer exists in the patient's mouth or enters the digestive tract, affecting patient safety. Therefore, there is a need for a material with increased long-term stability of the orthodontic device and safety when wearing the device by a patient through improved interlayer bonding.

In addition, when the existing multi-layer sheet is subjected to a strong impact, permanent deformation accompanied by whitening of the intermediate layer polymer material occurs, and the performance of the device rapidly deteriorates. Therefore, it is necessary to increase the durability of the device by making the interlayer portion of the multi-layer material have a high elastic recovery force capable of resisting external forces.

US Registered Patent Publication No. 9655691 (2017.05.23)

The present invention is to solve the problems of the prior art described above, and an object of the present invention relates to a method for manufacturing a multi-layered sheet for transparent orthodontics, and more particularly, it is a transparent orthodontic material necessary for orthodontic treatment, and is composed of multiple layers. To provide a method for manufacturing a transparent orthodontic multi-layer sheet that can increase orthodontic retention, reduce patient pain, and increase stability of an orthodontic device and safety when worn by a patient by having excellent interlayer bonding and durability.

In order to achieve the above object, one aspect of the present invention is a step of (a) mounting the soft thermoplastic polymer material in a roll state to the upper roll and the lower roll of the laminator, respectively, (b) the upper roll and the lower roll Raising the temperature, (c) laminating the roll sheets of the soft thermoplastic polymer material mounted on the upper roll and the lower roll in a pressing roll, and (d) laminating the soft thermoplastic polymer material while laminating the hard It provides a method for producing a multi-layer sheet for transparent correction comprising the step of mounting a thermoplastic polymer material on a central roll of a laminator and inserting it into the pressing roll in progress of lamination to prepare a multi-layer sheet.

In one embodiment of the present invention, in the step (b), the elevated temperature of the upper roll and the lower roll may be a transparent correction multi-layer sheet manufacturing method, characterized in that 110 to 140 ℃.

In one embodiment of the present invention, in the step (c), the pressure of the pressing roll may be a transparent correction multi-layer sheet manufacturing method, characterized in that 0.2 to 1.0 KPa.

In an embodiment of the present invention, in the step (c), the lamination speed of the pressing roll may be a method of manufacturing a multi-layered sheet for transparent correction, characterized in that 0.5 to 4.5 m/min.

In one embodiment of the present invention, the flexible thermoplastic polymer material may be a transparent orthodontic multi-layer sheet manufacturing method, characterized in that the flexible polyurethane.

In one embodiment of the present invention, the rigid thermoplastic polymer material may be a method of manufacturing a multi-layer sheet for transparent correction, characterized in that the rigid polyurethane.

In one embodiment of the present invention, the flexible thermoplastic polymer material may be a transparent orthodontic multi-layer sheet manufacturing method, characterized in that it has a hardness (hardness) of 85 to 95A.

In one embodiment of the present invention, the rigid thermoplastic polymer material has a yield strength of 40 MPa or more and 60 MPa or less, and has an elastic modulus (Young's modulus) of 1500 MPa or more and 2200 MPa or less. It may be a method of making a layer sheet.

According to one aspect of the present invention, the transparent orthodontic multi-layer sheet manufactured according to the present invention has excellent orthodontic holding power due to less deformation at the tooth deformed position compared to the conventional material for a long period of time, and has excellent interlayer bonding strength, resulting in durability and safety when worn by patients. can be improved

In addition, since the outer layer is made of a soft polymer material to give flexibility, it is possible to reduce the pain of the patient during the initial correction.

In addition, as the intermediate layer is made of a hard polymer material and has high elastic recovery force, interlayer bonding strength and durability with the outer layer may be improved.

The effects of the present invention are not limited to the above effects, and it should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a perspective view illustrating a multi-layered sheet for transparent correction manufactured according to an embodiment of the present invention.
2 is a schematic diagram showing a method of manufacturing a multi-layer sheet for transparent correction according to an embodiment of the present invention.
3 is a flowchart illustrating a method of manufacturing a multi-layer sheet for transparent correction according to an embodiment of the present invention.
4 (a) and (b) is a comparison of the yield strength (Yield strength) and elastic modulus (Young's modulus) between the transparent orthodontic multi-layer sheet, the intermediate layer, and the conventional material manufactured according to an embodiment of the present invention, respectively. It is a graph.
5 is a graph comparing peel strength between a multi-layer sheet for transparent correction manufactured according to an embodiment of the present invention and a conventional material.
6 is a photograph comparing the recovery rate after deformation between the multi-layer sheet for transparent correction manufactured according to an embodiment of the present invention and a conventional material.
7 is a graph comparing the retention rate of orthodontic force between the multi-layer sheet for transparent correction manufactured according to an embodiment of the present invention and a conventional material.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in several different forms, and thus is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is "connected" with another part, this includes not only the case of being "directly connected" but also the case of being "indirectly connected" with another member interposed therebetween. . In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view illustrating a multi-layered sheet for transparent correction manufactured according to an embodiment of the present invention.

Referring to FIG. 1 , the transparent orthodontic multi-layer sheet 1000 manufactured according to the present invention has a triple-layer structure including a first outer layer 100 , a second outer layer 200 , and an intermediate layer 300 . can be

The transparent orthodontic multi-layer sheet 1000 manufactured according to the present invention differs from the conventional single-layer material sheet by configuring the material of the outer layer in contact with the soft tissue in the oral cavity and the inner layer providing rigidity differently over time. It is possible to reduce discomfort and pain inflicted on the patient while maintaining the corrective power.

In this case, the first outer layer 100 and the second outer layer 200 constitute the outer layer of the transparent orthodontic multi-layer sheet 1000 and are in contact with the soft tissue in the oral cavity, and may be made of a soft thermoplastic transparent polymer material. That is, the first outer layer 100 and the second outer layer 200 are made of a soft polymer material to give flexibility to the transparent orthodontic multi-layer sheet 1000, and when a deformation force is applied, complex stress is applied to provide high correction. It can provide holding force and elastic recovery force.

The intermediate layer 300 constitutes the inner layer of the transparent orthodontic multi-layer sheet 1000 and provides orthodontic force for tooth movement, and may be made of a rigid thermoplastic transparent polymer material. That is, the intermediate layer 300 is made of a hard polymer material to give strength to the transparent orthodontic multi-layer sheet 1000, and can provide an orthodontic force for applying a force in the direction the teeth want to move.

According to an embodiment, the first outer layer 100 and the second outer layer 200 may be made of a flexible thermoplastic polyurethane (TPU).

Polyurethane has the characteristics of both rubber and plastic, and is a non-toxic material without harmful substances such as environmental hormones and TVOC. In addition, it is an elastic material that does not require a separate plasticizer, and has the highest abrasion resistance among thermoplastic elastomers that can be plastically processed by heat.

Accordingly, the first outer layer 100 and the second outer layer 200 prepared according to the present invention are made of a flexible polyurethane having a high strain recovery rate to give flexibility to the transparent orthodontic multi-layer sheet 1000, , it is possible to reduce the pain inflicted on the patient at the initial stage of orthodontic treatment.

Meanwhile, the first outer layer 100 and the second outer layer 200 manufactured according to the present invention may be configured to have a thickness of 20 μm or more and 200 μm or less. At this time, if the thickness of the first outer layer 100 and the second outer layer 200 is less than 20 μm, the flexibility of the transparent orthodontic multi-layer sheet 1000 may be reduced because it cannot sufficiently receive elastic deformation, and the If the thickness of the first outer layer 100 and the second outer layer 200 exceeds 200 μm, the thickness of the transparent orthodontic multi-layer sheet 1000 may be excessively thick, so that the patient's wearing comfort may be reduced.

In this case, the first outer layer 100 and the second outer layer 200 are preferably configured to have a hardness of 60A or more and 100A or less. If the hardness of the first outer layer 100 and the second outer layer 200 is less than 60A, there is a fear that sufficient strength for maintaining orthodontic force cannot be provided when in contact with the teeth, and if it exceeds 100A, the strength of the outer layer is excessively increased Therefore, it may not provide sufficient elasticity, and the pain relief of the patient may be reduced.

According to one embodiment, the intermediate layer 300 may be made of a rigid thermoplastic polyurethane (Thermoplastic Poly Urethane, TPU).

Among the conventional multi-layer materials, transparent polymer materials such as PET, PE, and PC were used as materials for securing corrective power, that is, strength as materials for interlayer materials. Have.

In addition, when the conventional multi-layer sheet is subjected to a strong impact, there is a problem in that the performance of the interlayer polymer material is rapidly deteriorated due to permanent deformation accompanied by whitening of the intermediate layer polymer material. That is, it is required to increase the durability of the multi-layer material by allowing the intermediate layer of the multi-layer material to have a high elastic recovery force capable of resisting an external force while having the strength to secure the corrective force.

The intermediate layer 300 manufactured according to the present invention is made of a hard polyurethane that improves durability by increasing interlayer bonding strength with the first outer layer 100 and the second outer layer 200. Multi-layer sheet for transparent correction (1000) It is possible to impart rigidity and a high strain recovery rate to the tooth, thereby providing improved orthodontic force.

Meanwhile, the intermediate layer 300 manufactured according to the present invention may be configured to have a thickness of 200 μm or more and 1500 μm or less. At this time, if the thickness of the intermediate layer 300 is less than 200 μm, it may be difficult to secure sufficient strength for maintaining the corrective force, and if the thickness of the intermediate layer 300 exceeds 1500 μm, the thickness of the transparent orthodontic multi-layer sheet 1000 is too thick. This may reduce the patient's wearing comfort.

In this case, the intermediate layer 300 is preferably configured to have a yield strength of 40 MPa or more and 60 MPa or less, and a Young's modulus of 1500 MPa or more and 2200 MPa or less. If the yield strength of the intermediate layer 300 is less than 40 MPa and the modulus of elasticity is less than 1500 MPa, it may not be possible to provide sufficient elastic deformation, so it may be difficult to provide sufficient mechanical strength for securing the corrective force, the yield strength is more than 60 MPa and the modulus of elasticity is more than 2200 MPa It can be difficult to relieve pain in patients in the early stages of orthodontic treatment.

In addition, the intermediate layer 300 may be configured to have a transmittance of 93% or more and 97% or less.

As such, the transparent orthodontic sheet 1000 manufactured according to the present invention is composed of multiple layers of soft polyurethane and rigid polyurethane having similar thermal properties, thereby increasing orthodontic holding power, reducing patient pain, and providing excellent interlayer bonding strength. As a result, durability can be improved, and safety can be increased when worn by patients.

Figure 2 is a schematic diagram showing a method of manufacturing a multi-layer sheet for transparent correction according to an embodiment of the present invention, Figure 3 is a flowchart showing a method for manufacturing a multi-layer sheet for transparent correction according to an embodiment of the present invention to be.

2 and 3, the present invention is a step of mounting the soft thermoplastic polymer material 100, 200 in a roll state to the upper roll 10 and the lower roll 20 of the laminator, respectively (S100), the upper roll (10) and raising the temperature of the lower roll 20 (S200), pressing the roll sheet of the soft thermoplastic polymer material 100 and 200 mounted on the upper roll 10 and the lower roll 20 Lamination after bonding in the roll 30 (S300) and while the soft thermoplastic polymer materials 100 and 200 are being laminated, the rigid thermoplastic polymer material 300 is mounted on the center roll 40 of the laminator and lamination is in progress. It is possible to provide a method of manufacturing a multi-layer sheet for transparent correction comprising the step (S400) of manufacturing the multi-layer sheet 1000 by being inserted into the compression roll 30 .

The method for manufacturing a multi-layer sheet for transparent correction of the present invention may be performed by a lamination process. At this time, lamination refers to a technology that protects the surface and increases strength and stability by overlaying one or more thin layers on the target object.

The laminator used in the present invention is configured to include an upper roll 10 , a lower roll 20 , a pressing roll 30 and a center roll 40 . At this time, the upper roll 10 and the lower roll 20 provide a soft thermoplastic polymer material in a roll state, the center roll 40 provides a hard thermoplastic polymer material in a roll state, and the compression roll 30 provides the soft thermoplastic polymer material in a roll state. Compress the thermoplastic polymer material and the rigid thermoplastic polymer material to bond them together.

Hereinafter, when explaining the method for manufacturing a multi-layer sheet for transparent correction of the present invention, first, the soft thermoplastic polymer materials 100 and 200 in a roll state are mounted on the upper roll 10 and the lower roll 20 of the laminator, respectively ( S100).

Then, the temperature of the upper roll 10 and the lower roll 20 is increased (S200).

At this time, according to one embodiment, the elevated temperature of the upper roll and the lower roll is characterized in that 110 to 140 ℃. During the lamination process, if the temperature of the upper roll 10 and the lower roll 20 is less than 110 ℃, the bonding strength between the soft thermoplastic polymer material and the hard thermoplastic polymer material may be reduced, and if it exceeds 140 ℃, the soft The quality of the transparent orthodontic multilayer sheet manufactured by partially melting the thermoplastic polymer material or the rigid thermoplastic polymer material may deteriorate.

Next, the soft thermoplastic polymer materials 100 and 200 in the form of roll sheets mounted on the upper roll 10 and the lower roll 20 are laminated after bonding in the pressing roll 30 (S300).

At this time, according to one embodiment, the pressure of the compression roll 30 is characterized in that 0.2 to 1.0 KPa. If the pressure of the compression roll 30 is less than 0.2 KPa, sufficient compression between the soft thermoplastic polymer materials 100 and 200 and the hard thermoplastic polymer material 300 may not be made, so that the peel strength may decrease, and if it exceeds 1.0 KPa Since the thickness of the manufactured multi-layer sheet for transparent orthodontics is too thin, a sufficient thickness may not be secured when manufacturing a transparent orthodontic device, and product performance may be deteriorated.

In addition, according to one embodiment, the lamination speed of the pressing roll 30 is characterized in that 0.5 to 4.5 m / min. If the lamination speed is less than 0.5 m/min, the manufacturing efficiency may be lowered when manufacturing the multi-layer sheet for transparent correction, and if it exceeds 4.5 m/min, sufficient compression time by the pressing roll 30 cannot be ensured, so that the interlayer peel strength is lowered can be

Finally, while the soft thermoplastic polymer material 100, 200 is being laminated, the rigid thermoplastic polymer material 300 is mounted on the center roll 40 of the laminator and inserted into the pressing roll 30 in the process of lamination to insert a multi-layer sheet ( 1000) is prepared (S400).

As such, through the manufacturing method of the present invention, it is possible to manufacture a transparent orthodontic multilayer sheet with improved interlaminar peel strength while the soft thermoplastic polymer material and the rigid thermoplastic polymer material have an effective thickness for performance as a transparent orthodontic material.

Hereinafter, the experimental contents for comparing the mechanical property values between the multi-layer sheet 1000 for transparent calibration manufactured according to the present invention and the conventional material will be described, and each mechanical property value is a universal testing machine (UTM). was measured through

The first outer layer 100 and the second outer layer 200 of the transparent orthodontic multi-layer sheet 1000 used in the experiment were made of soft polyurethane, and the middle layer 300 was made of rigid polyurethane. . In addition, the outer layer of the conventional material is made of a flexible polyurethane, and the inner layer is configured to be made of a hard polyester.

In this case, the universal testing machine (UTM) is an experimental instrument that applies stress to the material to find out the most basic mechanical properties of the polymer material, and then measures the resulting strain to find out the physical properties of the material. Experiments such as tensile, peeling, and bending were conducted in a way that measures the LOAD value until the specimen deforms with respect to the force applied to each specimen. Since the detailed experimental method is a known fact, it will be omitted.

4 (a) and (b) is a comparison of the yield strength (Yield strength) and elastic modulus (Young's modulus) between the transparent orthodontic multi-layer sheet, the intermediate layer, and the conventional material manufactured according to an embodiment of the present invention, respectively. It is a graph.

4, the conventional material was measured to have a yield strength of about 30 MPa to 40 MPa and an elastic modulus of 1500 MPa to 1700 MPa, and the transparent orthodontic multilayer sheet 1000 prepared according to the present invention is about 40 MPa to 60 MPa It was measured to have a yield strength of 1200 MPa and an elastic modulus of 1200 MPa to 2000 MPa.

That is, the transparent orthodontic multi-layer sheet 1000 of the present invention allows greater elastic deformation compared to conventional materials, thereby reducing the pain applied to the patient at the initial stage of orthodontic treatment and improving safety when wearing the patient.

5 is a graph comparing peel strength between a multi-layer sheet for transparent correction manufactured according to an embodiment of the present invention and a conventional material.

Referring to Figure 5, the transparent calibration multi-layer sheet 1000 prepared according to the present invention and a specimen including a surface where the outer layer and the middle layer are not bonded to the conventional material were prepared, and the peel strength was measured with a universal tester. As shown in FIG. 4, the conventional material was measured to have a peel strength of about 0.1N/cm to 0.15N/cm, and the transparent orthodontic multilayer sheet 1000 prepared according to the present invention was about 0.2N/cm It was measured to have more than peel strength.

That is, the transparent orthodontic multi-layer sheet 1000 manufactured according to the present invention has a peel strength of about 2 to 3 times that of a conventional material, thereby improving interlayer bonding strength and preventing the occurrence of delamination between layers. Accordingly, it is possible to prevent performance degradation due to the peeling phenomenon and the peeling layer from being present in the patient's oral cavity or flowing into the digestive tract, thereby compromising the safety of the patient.

6 is a photograph comparing the recovery rate after deformation between a multi-layer sheet for transparent correction prepared according to an embodiment of the present invention and a conventional material, and FIG. 7 is a multi-layer for transparent correction prepared according to an embodiment of the present invention. It is a graph comparing the retention rate of orthodontic force between the sheet and the conventional material.

Referring to FIG. 6 , the multi-layer sheet 1000 for transparent correction prepared according to the present invention and the conventional material were manufactured as a 1X8cm specimen, and the amount of change for 24 hours after bending was measured. As shown in FIG. 6 , in the case of the conventional material, it can be seen that the recovery rate after deformation is relatively low because a relatively large angle is maintained for 24 hours after bending. ), it can be seen that the recovery rate after deformation is relatively large, as it is recovered almost similar to the initial state for 24 hours after bending.

Referring to FIG. 7 , the transparent orthodontic multilayer sheet 1000 and the conventional material prepared according to the present invention were manufactured as a specimen for measuring flexural strength, and the orthodontic force retention rate was measured through the strain recovery rate using a universal testing machine. As shown in FIG. 7 , in the case of a conventional material, it can be confirmed that the corrective force decreases relatively quickly with time, and the corrective force decreases significantly after a certain period of time, and in the case of the transparent orthodontic multilayer sheet 1000 of the present invention It can be seen that the corrective force decreases relatively slowly with time, so that the corrective force is maintained at a certain level even after a certain period of time has passed.

As such, the transparent orthodontic multilayer sheet 1000 manufactured according to the present invention has excellent orthodontic holding power due to less deformation at the tooth deformed position compared to conventional materials, and excellent interlayer bonding strength, so durability and safety when worn by a patient can be improved. have.

The foregoing description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

1000 clear proofing multilayer sheet
100 first outer layer
200 second outer layer
300 mezzanine
10 upper roll
20 rolls per day
30 crimp rolls
40 center roll

Claims (8)

(a) mounting the soft thermoplastic polymer material in a roll state to the upper roll and the lower roll of the laminator, respectively;
(b) raising the temperature of the upper roll and the lower roll;
(c) laminating after bonding the roll sheets of the soft thermoplastic polymer material mounted on the upper roll and the lower roll in a pressing roll; and
(d) while the soft thermoplastic polymer material is being laminated, the hard thermoplastic polymer material is mounted on the central roll of the laminator and inserted into the pressing roll in the process of lamination to prepare a multi-layer sheet,
The flexible thermoplastic polymer material is a flexible polyurethane, the rigid thermoplastic polymer material is a rigid polyurethane,
The rigid thermoplastic polymer material has a yield strength of 40 MPa or more and 60 MPa or less, and is configured to have a Young's modulus of 1500 MPa or more and 2200 MPa or less,
The peel strength (Peel strength) representing the interlayer bonding force between the soft thermoplastic polymer material and the hard thermoplastic polymer material is 0.2N/cm or more of a transparent orthodontic multi-layer sheet manufacturing method. According to claim 1,
In the step (b), the temperature of the raised upper roll and the lower roll is 110 to 140 ℃ transparent correction multi-layer sheet manufacturing method, characterized in that. According to claim 1,
In the step (c), the pressure of the pressing roll is a transparent correction multi-layer sheet manufacturing method, characterized in that 0.2 to 1.0 KPa. According to claim 1,
In the step (c), the lamination speed of the pressing roll is a transparent correction multi-layer sheet manufacturing method, characterized in that 0.5 to 4.5 m / min. delete delete According to claim 1,
The flexible thermoplastic polymer material is a transparent orthodontic multi-layer sheet manufacturing method, characterized in that it has a hardness (hardness) of 85 to 95A. delete

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