KR102349694B1 - A novel thermoplastic polyurethane-silica composite for orthodontic power chain and a method of preparing the same - Google Patents

Abstract

The present invention relates to a thermoplastic polyurethane-silica composite for an orthodontic power chain and a manufacturing method thereof, and more particularly, to a thermoplastic polyether-based polyurethane containing 0.2 to 5 wt% of nano-sized silica particles based on the total weight. A method of manufacturing a thermoplastic polyether-based polyurethane-silica composite using a thermoplastic polyether-based polyurethane-silica composite and an extrusion process, including a substrate, wherein the silica particles are dispersed inside the thermoplastic polyether-based polyurethane substrate provides

Description

A novel thermoplastic polyurethane-silica composite for orthodontic power chain and a method of preparing the same

To a thermoplastic polyurethane-silica composite, and more particularly, to a thermoplastic polyurethane-silica composite for an orthodontic power chain and a method for manufacturing the same.

The elastic materials used for orthodontic treatment mainly include orthodontic rubber bands, power chains, and nickel-titanium coil springs.

Among them, the power chain is a rubber chain made of a polymer material and is used for the purpose of moving the teeth in a desired direction because it connects the brackets attached to the teeth. Power chains are mainly manufactured using elastic materials such as latex or polyurethane. Currently, they are not produced in Korea, but are imported in full. They tend to avoid its use.

Looking at the prior art related to the power chain, there is Republic of Korea Utility Model Registration No. 20-0437951, which relates to an orthodontic elastic body molded of silicone or synthetic rubber.

Typically, as a polymer for power chains, thermoplastic polyurethane is used, and the thermoplastic polyurethane has transparent optical properties, so it meets aesthetics as a material for orthodontic treatment, is harmless to the human body, and is easy to process. However, such an elastomer has a high elongation, but has a lower Young's modulus compared to other polymer materials, so mechanical properties should be improved by adding a reinforcing material.

In particular, in order to manufacture a composite material for a power chain suitable for orthodontic treatment, mechanical properties must be satisfied, and reinforcement of an appropriate color and size is required. In consideration of aesthetic factors, it is necessary to manufacture a composite material having an optimal composition ratio containing suitable mechanical properties while maintaining optical properties.

The soft segment of the polyurethane is largely divided into two types, a polyester series and a polyether series. Polyester-type polymers have the advantage of high resistance to hydrolysis, but are yellowed due to poor chemical and physical resistance. cause the phenomenon Conversely, in the case of polyether-based polyurethane, yellowing can be reduced by taking advantage of good physical properties and chemical resistance.

An object of the present invention is to provide an organic-inorganic composite material for a power chain having better physical properties and a method for manufacturing the same, which can solve various problems including the above problems. However, these problems are exemplary, and the scope of the present invention is not limited thereto.

details:

According to one aspect of the present invention, a thermoplastic polyether-based polyurethane containing nano-sized silica particles of 0.2 to 5% by weight based on the total weight is included, and the silica particles are dispersed in the thermoplastic polyether-based polyurethane. A thermoplastic polyether-based polyurethane-silica composite is provided.

According to another aspect of the present invention, there is provided a thermoplastic polyether-based polyurethane-silica composite film prepared by molding the thermoplastic polyether-based polyurethane-silica composite.

According to another aspect of the present invention, there is provided an orthodontic power chain manufactured by processing the thermoplastic polyether-based polyurethane-silica composite film.

According to another aspect of the present invention, injecting a predetermined weight ratio of thermoplastic polyether type polyurethane and nano-sized silica particles into the hopper of the extruder; and

Operating the extruder and recovering the extruded composite material from the outlet of the extruder, the thermoplastic polyether-based polyurethane-based method for producing a silica composite is provided.

According to another aspect of the present invention, injecting a predetermined weight ratio of thermoplastic polyether type polyurethane and nano-sized silica particles into the hopper of the extruder; and

operating the extruder and recovering the extruded composite pellets from the outlet of the extruder;

A film processing step of processing the composite pellets into a film; and

A method of manufacturing a power chain for orthodontics using a thermoplastic polyether-based polyurethane-silica composite is provided, comprising a film forming step of forming the film in the form of a power chain for orthodontics.

According to an embodiment of the present invention made as described above, it is possible to manufacture a thermoplastic polyether-based polyurethane-silica composite material for a power chain with improved various properties compared to a conventional power chain. However, the scope of the present invention is not limited by these effects.

1 is a series of shots of polyester (top) or polyether (bottom) series thermoplastic polyurethane (TPU) composite pellets containing silica of various concentrations according to an embodiment of the present invention manufactured through extrusion. are pictures of
2 is a graph showing the results of measuring the tensile strength (upper) and tensile modulus (lower) of the polyether-based thermoplastic polyurethane composite prepared according to an embodiment of the present invention.
3 is a graph showing the stress relaxation test results of the polyether-based thermoplastic polyurethane type composite according to an embodiment of the present invention.
4 is a scanning electron microscope (SEM) photograph of the fracture surface analysis result of the polyether-based thermoplastic polyurethane composite material according to an embodiment of the present invention.
5 is a graph showing the porosity measurement result of the polyether-based thermoplastic polyurethane composite prepared according to an embodiment of the present invention.
6 shows the results of thermogravimetric analysis performed to compare the thermal stability of three types of power chains currently on the market and power chains using polyester-based and polyether-based thermoplastic polyurethanes manufactured according to an embodiment of the present invention; It is a graph.
7 is a photograph prepared in the form of a power chain for orthodontics by cutting a polyether-based thermoplastic polyurethane-silica composite film according to an embodiment of the present invention manufactured through extrusion.

Definition of Terms:

As used in this document, the term "thermoplastic" is the opposite of thermoset, which is a material that does not melt and decomposes when heat is applied. possible properties of the material.

As used herein, the term "polymer composite" refers to a material to which a polymer is blended with other organic and/or inorganic materials to increase the physical properties of the polymer or to impart electrical properties.

The term "polyurethane" used in this document refers to a polymer compound in which urethane bonds are repeatedly included in the main chain of the polymer, and consists of a repeating structure of a soft segment and a hard segment. . Polyurethane is a polyol such as polyester diol, polycaprolactone diol, and polycarbonate diol having hydroxyl groups (-OH) at both ends, and diisocyanate such as TDI (toluene diisocyanate), MDI (methylene diphenyl diisocyanate) and NDI (naphthalene diisocyanate). It is made by polymerization of isocyanate to make a prepolymer having an isocyanate group (-N=C=O) at the terminal, and then addition polymerization with a chain extender such as amine or diol. In this case, the polyol portion constitutes the soft fragment, and the urethane formed by reacting isocyanate with an amine or hydroxyl group, and a urea bond and unreacted portion constitute the hard fragment. By varying the raw material composition of the soft segment and the hard segment, various designs are possible, from rubber-like elastomers to thermosetting engineering plastics with high rigidity. The polyol is further divided into polyester-based polyol and polyether-based polyol. Polyurethane prepared using polyester-based polyol is polyester-based polyurethane. Polyurethane prepared using polyether-based polyol is polyether-based polyurethane. is called

DETAILED DESCRIPTION OF THE INVENTION:

According to one aspect of the present invention, it includes a thermoplastic polyether-based polyurethane substrate containing nano-sized silica particles of 0.2 to 5% by weight based on the total weight, wherein the silica particles are inside the thermoplastic polyether-based polyurethane substrate A thermoplastic polyether-based polyurethane-silica composite, dispersed in

In the composite, the silica may be nanoparticles having a diameter of 100 to 990 nm, 200 to 900 nm, 300 to 850 nm, 400 to 800 nm, but is not limited thereto. .

In the composite material, the silica may be included in an amount of 0.2 to 5.0, 0.3 to 4.0, or 0.5 to 3.0 wt%.

In the composite material, the thermoplastic polyether-based polyurethane substrate contains diisocyanate, polyalkylene oxide, 1,4-butadiene, lubricant, antioxidant and hydrolytic agent in an amount of 0.03% or less based on the total weight of polyurethane it may have been

The composite material may be prepared through an extrusion process to disperse the silica particles in the thermoplastic polyether-based polyurethane substrate.

According to another aspect of the present invention, there is provided a thermoplastic polyether-based polyurethane-silica composite film prepared by molding the thermoplastic polyether-based polyurethane-silica composite.

The thermoplastic polyether-based polyurethane-silica composite film may be prepared by pressing or film extrusion of the thermoplastic polyether-based polyurethane-silica composite.

The composite film may have a tensile strength of 51 MPa or more and a tensile modulus of 15.1 MPa or more.

According to another aspect of the present invention, the thermoplastic polyether-based polyurethane-silica composite material or the thermoplastic polyether-based polyurethane-silica composite film may be provided as a composite material for orthodontic power chains.

According to another aspect of the present invention, injecting a predetermined weight ratio of thermoplastic polyether type polyurethane and nano-sized silica particles into the hopper of the extruder; and

Operating the extruder and recovering the extruded composite material from the outlet of the extruder, the thermoplastic polyether-based polyurethane-based method for producing a silica composite is provided.

According to another aspect of the present invention, injecting a predetermined weight ratio of thermoplastic polyether type polyurethane and nano-sized silica particles into the hopper of the extruder; and

operating the extruder and recovering the extruded composite pellets from the outlet of the extruder;

A film processing step of processing the composite pellets into a film; and

A method of manufacturing a power chain for orthodontics using a thermoplastic polyether-based polyurethane-silica composite is provided, comprising a film forming step of forming the film in the form of a power chain for orthodontics.

The urethane group of the thermoplastic polyurethane and the hydroxyl group of the silica may interact to form a hydrogen bond. Accordingly, the present inventors investigated whether it is possible to increase the mechanical properties of the thermoplastic polyurethane by adding silica particles having a hydroxyl group (-OH) in the terminal group in order to strengthen the mechanical properties through interaction with the polar functional group of the thermoplastic polyurethane. . The present inventors performed tensile strength, tensile modulus, scanning electron microscope, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and mercury porosimetry analysis to analyze the mechanical properties, optical properties and thermal properties of the material. The correlation between mechanical and thermal properties according to the structure was investigated. In addition, a comparative analysis was performed to determine which of the polyester-based and polyether-based polyurethanes is more suitable. As a result, when compounding using polyester-based polyurethane, it was confirmed that yellowing occurred, and as a result of replacing it with ether-based thermoplastic polyurethane, yellowing was suppressed, which is one of the most important factors for aesthetics. The transparency of the composite material suitable for orthodontic power chains was secured.

Hereinafter, the present invention will be described in more detail through Examples and Experimental Examples. However, the present invention is not limited to the synthesis examples, examples and experimental examples disclosed below, but can be implemented in various different forms, and the following synthesis examples, examples and experimental examples are provided so that the disclosure of the present invention is complete. and is provided to fully inform those of ordinary skill in the scope of the invention.

Example: Preparation of Thermoplastic Polyurethane-Silica Composite for Power Chain

Thermoplastic polyurethane is K-492A (polyester type) and K-395AB (polyether type) purchased from Kolon Industries, and silica particles are MUS-5 products purchased from Ajou Industries, which were dried for 4 hours before extrusion. .

For composite production, a co-rotating twin screw extruder (SM-PLATEK, TEK-25, L/D=40, 25 mm) was used. After the thermoplastic polyurethane and silica particles were weighed and mixed, the mixture was inserted into the main feeder. The temperature of the barrel was set sequentially from 170°C to 215°C from the hopper to the die. The soft segment of K-492A is polyester, and K-395AB is polyether. As can be seen in Table 1, when K-492A thermoplastic polyurethane was used, the silica particle content in the composite material was prepared in a total of 5 types of 0, 1, 2, 5, and 10 wt%. However, it was confirmed that when pellets were prepared using polyester-based polyurethane, the yellowing phenomenon was strengthened as the silica content increased. Since the orthodontic power chain composite material is an important factor in aesthetics, if yellowing occurs in the material itself, no matter how good its mechanical properties are, it can be said that it is not suitable for use as a power chain. Accordingly, the present applicants determined that the content of K-395AB thermoplastic polyurethane and silica particles in the manufacture of a composite of 0, 0.5, 1, 1.5, 2, and 5% by weight of granular A composite material of content ratio was prepared.

Mixing ratio according to various embodiments of the present invention Example Polyurethane type Polyurethane content (wt%) Silica content (wt%) One polyester type 100 0 2 99.0 1.0 3 98.0 2.0 4 95.0 5.0 5 90.0 10.0 6 polyether type 100 0 7 99.5 0.5 8 99.0 1.0 9 98.5 1.5 10 98.0 2.0 11 95.0 5.0

The color and shape of the prepared pellets are shown in FIG. 1, and the polyether-based polyurethane composite pellets prepared according to Examples 1 to 11 were dried at 80° C. for 12 hours and then using a high-temperature press to a film of 60 to 80 μm. was molded with In addition, power chain products of Ormco (USA), American orthodontics (USA), and Xceldent (China) that are currently on the market were pressed and manufactured into films of the same thickness to compare the properties of composite materials.

Experimental Example 1: Analysis of mechanical properties

Next, the present inventors analyzed the effect of the interaction between silica and polyurethane in a total of 11 types of thermoplastic polyurethane composite specimens prepared according to Examples 1 to 11 on the mechanical properties of the composite and analyzed the effects of the domestic production of power chains. To determine suitability, experiments were performed to measure tensile strength, elongation at break, and tensile modulus.

As shown in FIG. 2 , a composite sample for each content ratio was prepared as a film, and mechanical properties were measured. As a comparative group, Xceldent power chain products made in China were pressed into a film and then measured together. Tensile strength and tensile modulus were measured at a speed of 500 mm/min using a universal testing machine (UTM, Instron, 3343). Measurements were made using samples. As a result of comparing the film properties of the thermoplastic polyether-based polyurethane-silica composite film according to an embodiment of the present invention and a commercially available product, 1.5 and 5 wt% silica-containing polyurethane prepared in Examples 9 and 11 of the present invention, respectively The composite material showed high tensile strength, and in particular, the 1.5 wt% composite material showed better tensile modulus than the Xceldent sample, which had the best mechanical properties among the three types of power chains.

As shown in FIG. 3, the stress (MPa) with respect to time was measured using a dynamic mechanical analyzer (DMA, TA Instrument, Q800). In the tensile test of FIG. 2 , two types of composite materials with the content ratio of 1.5 and 5% by weight having the best physical properties were selected and processed, and three types of power chain products from foreign power chains were press-processed into films. In the stress relaxation test, elastic force for 1 hour was measured in a state where 1% of the initial length was applied. As a result, both at 1.5 and 5 wt % of silica content, higher stress values were recorded than conventional commercial products. This means that when the silica-polyurethane composite film of the present invention is used as a power chain, the teeth can be moved with a stronger force.

This result is presumed to be a result of the interaction between the thermoplastic polyurethane and silica particles and the ratio of hard fragments of the thermoplastic polyurethane.

Experimental Example 2: fracture surface analysis

Next, the present inventors prepared polyether-based polyurethane composites (silica content 0, 1.5 and 5 wt%) prepared in Examples 6, 9 and 11, which showed excellent tensile strength, in order to analyze the mechanical properties according to the dispersion degree of the composite material. The fracture surface was photographed with a scanning electron microscope and analyzed. The fracture surface was photographed using a scanning electron microscope (FE-SEM, Hitachi, S-4300SE) manufactured by Hitachi. As a result, as shown in FIG. 4, the fracture surface of the thermoplastic polyurethane composite containing 1.5 and 5 wt% silica has silica particles dispersed inside the thermoplastic polyurethane, and the silica particles interact with the polyurethane substrate by hydrogen bonding and was found to be

Experimental Example 3: Density and porosity measurement

Next, the present inventors measured the density and porosity of the two polyether-based polyurethane composites using a mercury porosimeter (Micrometrics, AutoPore IV, USA) at various pressures. As a result, as shown in FIG. 5 , the polyurethane composite film to which silica particles were added showed higher density and lower porosity compared to the polyurethane film to which silica particles were not added. Detailed values are shown in Table 2, and the decrease in porosity was significant. It can be concluded that the reason for this phenomenon is that the pore size is reduced and the density of the polymer composite is increased due to the interaction through hydrogen bonding between the polymer matrix and the silica particles, which is a reinforcement material.

Density and porosity of polyurethane and polyurethane-silica composites according to an embodiment of the present invention Metrics unit Example 6 Example 9 bulk density g/cm ³ 1.14 1.15 bone density g/cm ³ 1.21 1.22 porosity % 6.17 5.89 Median pore size (volume) nm ³ 8.0 7.9 Median pore size (area) nm ² 4.8 4.8 Average pore size (4V/A) nm 7.2 7.2

Experimental Example 4: Thermal stability analysis of composites

The present inventors performed thermogravimetric analysis (TGA) to investigate whether there is no change in the thermal stability of the composite after the addition of silica particles. In the case of thermogravimetric analysis, the temperature is increased at a constant rate and the change in weight of the sample is observed. Through this, the composition and composition ratio of the substance can be identified. Before TGA analysis, both the polymer composite material and the commercialized power chain were dried in an oven at 70° C. for 12 hours, and then the experiment was performed. TGA analysis was performed using a thermogravimetric analyzer (Q50, TA Instruments, USA) at a heating rate of 10° C./min in a temperature range of 30 to 700° C. under nitrogen conditions. As a result, in the graph shown in FIG. 6 , the first differential peak point of pyrolysis means the decomposition of the hard fragment of the thermoplastic polyurethane, and the second differential peak point means the degradation of the soft fragment of the thermoplastic polyurethane. Both three hard/soft decomposition temperatures, which are characteristic of thermoplastic polyurethane, were observed in the three commercial companies and the composite material of the present invention. In addition, as shown in Table 3, the decomposition temperature (T _max1 ) of the soft fragment in the polyurethane and the decomposition temperature (T _max2 ) of the hard fragment in the polyurethane were compared with the residual material remaining after the thermogravimetric analysis was finished. Residues may be caused by carbonization of polymers or inorganic silica as additives. The content of residual substances was much higher in the polyether-type polyurethane-silica polymer composite than in polyurethane without silica particles. It is estimated that the amount of silica nanoparticles that are not thermally decomposed within the TGA temperature range increases as the interfacial adhesion increases as the silica nanoparticles are dispersed in the polyurethane, or that ash and tar increase.

Thermal decomposition temperature and unreacted residue content of polyurethane composite material and commercial power chain material according to an embodiment of the present invention Kinds brand or
Example number Metrics T _max1 (℃) T _max2 (℃) Residue content
(weight%) commercial goods Ormco 314 374 7.1 American orthodontics 318 391 7.2 Xceldent 331 409 2.4 Polyester based composites Example 1 354 408 2.3 Example 2 338 406 3.8 Example 4 346 406 8.5 Polyether based composites Example 6 355 418 5.6 Example 9 353 413 14.1 Example 11 350 415 16.0

Experimental Example 5: Fabrication of the power chain structure

Next, the present inventors manufactured the power chain structure mentioned in Example 1 in the form of a power chain as shown in FIG. 7 with the polyether-based polyurethane composite film. The polyether-based thermoplastic polyurethane-silica composite prepared in Example 1 was film-formed using a hot press to have a thickness of 500 μm, which is similar to the thickness of commercial power chain products (Ormco, American orthodontics, Xceldent), It was manufactured in the form of a power chain using a cutting tool.

Although the present invention has been described with reference to the above-described examples and experimental examples, these are merely exemplary, and those of ordinary skill in the art will realize that various modifications and equivalent other examples and experimental examples are possible therefrom. will understand Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims (13)

A thermoplastic polyether-based polyurethane substrate containing silica particles having a nano-sized terminal group of hydroxyl (-OH) in an amount of 0.2 to 5.0% by weight based on the total, wherein the silica particles are inside the thermoplastic polyether-based polyurethane substrate Dispersed, thermoplastic polyether based polyurethane-silica composite. According to claim 1,
The silica is nanoparticles having a diameter of 100 to 990 nm, a thermoplastic polyether-based polyurethane-silica composite. According to claim 1,
The thermoplastic polyether-based polyurethane base includes diisocyanate, polyalkylene oxide, 1,4-butadiene, lubricants, antioxidants and hydrolysers in an amount of 0.03% or less based on the weight of the total polyurethane, thermoplastic polyether A series of polyurethane-silica composites. According to claim 1,
A thermoplastic polyether-based polyurethane-silica composite material produced through an extrusion process to disperse the silica particles in the thermoplastic polyether-based polyurethane substrate. The thermoplastic polyether-based polyurethane-silica composite film produced by molding the thermoplastic polyether-based polyurethane-silica composite of any one of claims 1 to 4. 6. The method of claim 5,
A thermoplastic polyether-based polyurethane-silica composite film having a tensile strength of 51 MPa or more and a tensile modulus of 15.1 MPa or more. The power chain for orthodontics manufactured by processing the thermoplastic polyether-based polyurethane-silica composite of any one of claims 1 to 4. 8. The method of claim 7,
A power chain for orthodontics manufactured by molding the thermoplastic polyether-based polyurethane-silica composite material. The power chain for orthodontics manufactured by processing the thermoplastic polyether-based polyurethane-silica composite film of claim 6 . 10. The method of claim 9,
A power chain for orthodontics produced by cutting and molding the thermoplastic polyether-based polyurethane-silica composite film. injecting silica particles having a predetermined weight ratio of thermoplastic polyether type polyurethane and nano-sized end groups of hydroxyl groups (-OH) into the hopper of the extruder; and
5. A method for producing a thermoplastic polyether-based polyurethane-silica composite of any one of claims 1 to 4, comprising the step of operating the extruder and recovering the extruded composite material from the outlet of the extruder. 12. The method of claim 11,
The silica particles: a certain weight ratio of the thermoplastic polyether-based polyurethane is a ratio of 0.2:99.8 to 5:95, the manufacturing method. injecting silica particles having a predetermined weight ratio of thermoplastic polyether type polyurethane and nano-sized end groups of hydroxyl groups (-OH) into the hopper of the extruder; and
operating the extruder and recovering the extruded composite pellets from the outlet of the extruder;
A film processing step of processing the composite pellets into a film; and
A method of manufacturing a power chain for orthodontics using the thermoplastic polyether-based polyurethane-silica composite of claim 1, comprising a film forming step of forming the film in the form of a power chain for orthodontics.

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