KR20200028863A - Thermoplastic polyurethane particles and method for preparing the same - Google Patents

Abstract

The present invention provides thermoplastic polyurethane particles formed from a thermoplastic polyurethane resin in a continuous matrix phase and having a particle diameter of 1 to 100 μm. The thermoplastic polyurethane particles have an average particle diameter (D50) of 20 to 50 μm, have a cumulative volume 10% particle diameter (D10) of 5 to 15 μm, and have a cumulative volume 90% particle diameter (D90) of 40 to 80 μm. The thermoplastic polyurethane particles have a D value of 5 to 20, wherein the D value represents the distribution of the particles. According to the present invention, material properties of a product to which the thermoplastic polyurethane particles are applied can be improved, thereby improving quality of the product.

Description

Thermoplastic polyurethane particles and methods for manufacturing the same {THERMOPLASTIC POLYURETHANE PARTICLES AND METHOD FOR PREPARING THE SAME}

The present invention relates to a thermoplastic polyurethane particle and a method for manufacturing the same.

Thermoplastic polyurethane particles are used in various industrial fields such as cosmetic, paint or coating fillers, hot melt adhesives, heat molded products, and polymerized toners. In particular, thermoplastic polyurethane particles having a small diameter of less than 100 µm are used for 3D printing products manufactured by SLS (Selective Laser Sintering) and color cosmetics. In order for the small-diameter thermoplastic polyurethane particles to be utilized for this purpose, the size and shape of the basically manufactured particles must be uniformly produced, and the better the flowability and dispersibility of the particles, the higher the quality of the manufactured products.

In order to manufacture such small-diameter thermoplastic polyurethane particles, the following three methods have been mainly used. Specifically, the method for producing the thermoplastic polyurethane particles is a grinding method represented by freeze grinding; A solvent-soluble precipitation method in which a precipitate is cooled by dissolving in a high-temperature solvent or dissolved in a solvent and then precipitated by adding a poor solvent; And a melt kneading method in which a thermoplastic resin and an incompatible resin are mixed in a mixer to form a composition having a thermoplastic resin in a dispersed phase and a thermoplastic resin and an incompatible resin in a continuous phase, and then the thermoplastic resin particles are obtained by removing the incompatible resin.

When producing particles through the grinding method, it is difficult to ensure uniformity of the size and shape of the produced thermoplastic polyurethane particles. In addition, since liquid nitrogen is used for cooling of the pulverization method, it takes a high cost compared to the particle obtaining process, and when a compounding process of adding a pigment, an antioxidant, etc. to the thermoplastic polyurethane resin raw material is added, it proceeds in a batch mode. Because of this, productivity is lowered compared to the continuous particle obtaining process. When the particles are produced through the solvent dissolution precipitation method and the melt-kneading method, a problem that other components such as a solvent may be detected as impurities in addition to the thermoplastic resin particles, which may be included per particle when particles having a small diameter are produced. The problem may be more serious because the amount of impurities may be higher. Due to the above-mentioned problems, when the small diameter thermoplastic polyurethane particles manufactured by the conventional method are applied to 3D printing products and color cosmetics, the quality of the products is deteriorated.

Accordingly, in the related art, there is a need for thermoplastic polyurethane particles having improved particle properties to be suitable for application to 3D printing products and color cosmetics.

Japanese Patent Application Publication No. 2001-288273 Japanese Patent Application Publication No. 2000-007789 Japanese Patent Application Publication No. 2004-269865

The present invention is to provide a thermoplastic polyurethane particle having excellent physical properties when manufacturing 3D printing products and color cosmetics.

According to a first aspect of the invention,

The present invention provides a thermoplastic polyurethane particle formed of a continuous phase from a thermoplastic polyurethane resin, having a particle diameter of 1 to 100㎛.

In one embodiment of the invention, the thermoplastic polyurethane particles have an average particle diameter (D ₅₀ ) of 20 to 50㎛.

In one embodiment of the invention, the thermoplastic polyurethane particles have a cumulative volume 10% particle diameter (D ₁₀ ) of 5 to 15㎛.

In one embodiment of the invention, the thermoplastic polyurethane particles have a cumulative volume 90% particle diameter (D ₉₀ ) of 40 to 80㎛.

In one embodiment of the present invention, the thermoplastic polyurethane particles have a D value of 5 to 20 calculated by the following equation (1).

[Calculation formula 1]

Here, D ₁₀ is a cumulative volume 10% particle diameter, D ₅₀ is an average particle diameter, and D ₉₀ is a cumulative volume 90% particle diameter.

In one embodiment of the present invention, the impurity content of the thermoplastic polyurethane particles is 50ppm or less.

In one embodiment of the present invention, the thermoplastic polyurethane particles have a glass transition temperature (T _g ) and a melting point in a DSC curve derived from an elevated temperature analysis of 10 ° C./min by Differential Scanning Calorimetry (DSC). The peak of the cold crystallization temperature (T _cc ) is shown at a temperature between (T _m ).

In one embodiment of the present invention, the thermoplastic polyurethane particles have an aspect ratio calculated by the following formula 2 is 1.00 or more and less than 1.05,

The degree of spheroidization calculated by the following formula (3) is 0.95 to 1.00.

[Calculation formula 2]

Aspect ratio = major axis / minor axis

[Calculation formula 3]

Roundness = 4 × area / (π × long axis ^ 2).

In one embodiment of the invention, the thermoplastic polyurethane particles have a compressibility of 7 to 15% calculated by the following equation (4).

[Calculation formula 4]

Compression degree = (compressed bulk density-relaxed bulk density) / compressed bulk density × 100.

In one embodiment of the present invention, the thermoplastic polyurethane particles have a compressed bulk density of 0.4 to 0.45 g / cm ³ .

In one embodiment of the present invention, the thermoplastic polyurethane particles have a flow time of 10 to 20 seconds.

According to the second aspect of the invention,

The present invention (1) feeding a thermoplastic polyurethane resin to the extruder to extrude;

(2) supplying the extruded thermoplastic polyurethane resin and air to the nozzle, contacting the thermoplastic polyurethane resin with air to granulate the thermoplastic polyurethane resin, and then discharging the granulated thermoplastic polyurethane resin; And

(3) After supplying the discharged thermoplastic polyurethane particles to a cooler, after cooling the thermoplastic polyurethane particles, there is provided a method for producing thermoplastic polyurethane particles comprising the step of obtaining cooled thermoplastic polyurethane particles.

In one embodiment of the present invention, the extruded thermoplastic polyurethane resin supplied to the nozzle in step (2) has a melt viscosity of 0.5 to 20 Pa · s.

In one embodiment of the present invention, air is supplied to the central portion and the outer portion based on the cross section of the nozzle in step (2), and the extruded thermoplastic polyurethane resin is supplied between the central portion and the outer portion to which air is supplied. .

In one embodiment of the present invention, the extruded thermoplastic polyurethane supplied between the air supplied to the outer portion and the center and the outer portion to which the air is supplied, based on the cross section in the discharge portion of the nozzle in step (2). The resin has a cross-sectional area ratio of 4: 1 to 6: 1.

In one embodiment of the present invention, the interior of the nozzle in step (2) is maintained at 250 to 350 ° C.

In one embodiment of the present invention, the discharge portion of the nozzle in step (2) is maintained at a temperature calculated by the following equation (5).

[Calculation formula 5]

Discharge temperature = glass transition temperature (T _g ) + (decomposition temperature (T _d ) -glass transition temperature (T _g )) × B

In the calculation formula 5, the glass transition temperature and decomposition temperature are values for the thermoplastic polyurethane, and B is 0.5 to 1.5.

The thermoplastic polyurethane particles according to the present invention have physical properties suitable for manufacturing 3D printing products and color cosmetics, and can improve the quality of applied products.

1 is an image schematically showing the shape of the thermoplastic polyurethane particles of the present invention.
2 is a process flow chart schematically showing a method of manufacturing a thermoplastic polyurethane particle according to the present invention.
Figure 3 is a cross-sectional view of the nozzle discharge portion showing the supply position of the thermoplastic polyurethane resin and air to the nozzle according to an embodiment of the present invention.

The specific examples provided according to the present invention can all be achieved by the following description. It should be understood that the following description is to describe preferred embodiments of the invention, and it is to be understood that the invention is not necessarily limited thereto.

In the following specification, for the numerical range, the expression "to" is used to mean including both the upper and lower limits of the range, and when the upper or lower limits are not included, "less than", " The expressions "over", "below" or "above" are used.

The present invention provides thermoplastic polyurethane particles having physical properties suitable for use in 3D printing products, color cosmetics, and the like that could not be obtained by a conventional particle manufacturing method. Hereinafter, the thermoplastic polyurethane particles according to the present invention will be described in detail.

Thermoplastic polyurethane particles

The present invention provides a thermoplastic polyurethane particle produced by extruding a thermoplastic polyurethane resin in contact with air to atomize it. The manufacturing method of the thermoplastic polyurethane particles according to the present invention is an improved method compared to the conventional grinding method, the solvent dissolution precipitation method, and the melt-kneading method, and the specific manufacturing method is described in the “Production Method of Thermoplastic Polyurethane Particles” section below. Explain.

The thermoplastic polyurethane particles according to the present invention have a particle diameter of 1 to 100 μm, more specifically 5 to 80 μm. When the particles have a particle diameter of less than 1 μm, the thermoplastic polyurethane particles are excessively dispersed, and thus it is difficult to realize the particle characteristics of the thermoplastic polyurethane in the product, and when the particles have a particle diameter of more than 100 μm, the particles are too large. For example, when applied to cosmetics, etc., the spreadability and the like are reduced, which is not suitable. The thermoplastic polyurethane particles have an average particle diameter (D ₅₀ ) (or 50% cumulative particle size) of 20 to 50 μm, more specifically 25 to 40 μm. Product materials such as color cosmetics that satisfy the average particle diameter of the above-described range may be uniformly dispersed while maintaining a proper distance between materials. The thermoplastic polyurethane particles have a cumulative volume 10% particle diameter (D ₁₀ ) of 5 to 15 μm, more specifically 7 to 12 μm. The thermoplastic polyurethane particles have a cumulative volume 90% particle diameter (D ₉₀ ) of 40 to 80 μm, more specifically 50 to 70 μm. In the present specification, the particle size distribution of the thermoplastic polyurethane particles was measured by a wet method using a particle size analyzer (Microtrac, S3500), and the specific method is described in the Examples below. Here, D ₁₀ , D ₅₀ , and D ₉₀ mean particle diameters in which the cumulative volume percentages in the cumulative volume distribution of the particles correspond to 10%, 50%, and 90%, respectively. Regarding the particle size distribution of the thermoplastic polyurethane particles, the thermoplastic polyurethane particles according to the present invention have a D value of 5 to 20, more specifically 10 to 15, and the D value is calculated by the following Equation 1.

[Calculation formula 1]

The D value is a numerical value indicating where particles having a larger cumulative volume 90% particle diameter (D ₉₀ ) and particles having a smaller cumulative volume 10% particle diameter (D ₁₀ ) are located based on particles having an average particle diameter (D ₅₀ ). It is one value. Here, particles having a relatively large particle diameter serve to support particles having an average particle diameter when applied together with particles having an average particle diameter, and particles having a relatively small particle diameter are average particle diameter when applied together with particles having an average particle diameter It serves to fill the voids between the particles having. The smaller the D value, the closer the particle diameter of the particles is distributed, and the larger the D value, the larger the D particle size is, the larger the particle diameter is. When the D value is small, the ratio of particles close to the average particle diameter is high, so it is difficult to obtain an effect due to the diversity of the particle size. On the other hand, when the D value is large, the ratio of particles distant to the average particle diameter is increased and the reference particle size is calculated Difficult to apply Average particle diameter When the particle satisfies the D value in the above-described range, the particles are distributed in a proper ratio of large particles and small particles around the average particle diameter, and thus can exhibit excellent properties when applied to 3D printing products and color cosmetics. .

In the present invention, the shape of the particles is evaluated in the following aspect ratio (aspect ratio) and roundness (roundness), the closer the aspect ratio and the degree of spheroidization is 1, the shape of the particles is interpreted as closer to the sphere. The aspect ratio is calculated by Equation 2 below.

[Calculation formula 2]

Aspect ratio = major axis / minor axis

In addition, the degree of spheronization is calculated by the following equation (3).

[Calculation formula 3]

Roundness = 4 × area / (π × long axis ^ 2)

To specifically describe the above calculation formula, FIG. 1 schematically showing thermoplastic polyurethane particles is provided. According to FIG. 1, in the calculation formulas 2 and 3, “long axis” means the longest distance among the vertical distances (d) between two parallel tangent lines of the 2D image (cross section) of the thermoplastic polyurethane particles, and “short axis” is It means the shortest distance among the vertical distances (d) between two parallel tangent lines of the 2D image (cross section) of the thermoplastic polyurethane particles. In addition, in the calculation formula 3, “area” means a cross-sectional area including the long axis of the thermoplastic polyurethane particles. 1 is an example of the case where the vertical distance (d) between two parallel tangent planes of the thermoplastic polyurethane particles is a long axis, and shows the area (A).

According to one embodiment of the present invention, the thermoplastic polyurethane particles according to the present invention may have an aspect ratio of 1.00 or more and less than 1.05, more specifically 1.02 or more and less than 1.05, and 0.95 to 1.00, and more specifically 0.98 to 1.00 It can have a degree of spheroidization. When the shape of the thermoplastic polyurethane particles satisfies the range of the aspect ratio and the degree of spheroidization described above, the flowability and uniformity of the thermoplastic polyurethane particles are increased to facilitate the handling of the particles in application to 3D printing products and color cosmetics, The 3D printing product and the color cosmetics to which the particles are applied can be improved in quality due to excellent flowability and dispersibility of the particles.

Numerical values according to the calculation formulas 2 and 3 are measured by converting the image of the thermoplastic polyurethane particles into an image using ImageJ (National Institutes of Health (NIH))-converting to a binary image and quantifying the degree of spheroidization of individual particles- It is possible.

The thermoplastic polyurethane particles according to the present invention are particles formed in a continuous matrix form from a thermoplastic polyurethane resin. Forming a continuous matrix phase from a thermoplastic polyurethane resin means forming a continuously dense structure of the thermoplastic polyurethane resin without additional components. By extruding the thermoplastic polyurethane resin, melting and then granulating the melt with air, the thermoplastic polyurethane particles are continuously produced with a dense structure. On the other hand, according to the conventional manufacturing method, since particles are formed by adding additional components or particles are formed through a discontinuous process of cooling and crushing, particles are not formed in a continuous matrix.

Particles formed in a continuous matrix form from a thermoplastic polyurethane resin have a high purity because basically no impurities are mixed in the production process of the particles. Here, "impurity" means a component other than a thermoplastic polyurethane that may be incorporated during particle production. Exemplary impurities include a solvent for dispersing the thermoplastic polyurethane resin, a heavy metal component included in the grinding or grinding process, and an unreacted monomer included in the polymerization process. According to one embodiment of the present invention, the impurity content of the thermoplastic polyurethane particles of the present invention may be 50 ppm or less, preferably 20 ppm or less, more preferably 5 ppm or less.

In addition, the particles may additionally have other properties as well as purity. As one of these characteristics, the thermoplastic polyurethane particles are between the glass transition temperature (T _g ) and the melting point (T _m ) in the DSC curve derived from the elevated temperature analysis of 10 ° C./min by differential scanning calorimetry (DSC). The peak of the cold crystallization temperature (T _cc ) appears at the temperature of. The thermoplastic polyurethane particles are spherical solid particles at room temperature. When these particles are subjected to an elevated temperature analysis using a differential scanning calorimeter, the fluidity gradually increases as the temperature increases. At this time, the thermoplastic polyurethane particles have a peak of the cold crystallization temperature (T _cc ) at a temperature between the glass transition temperature (T _g ) and the melting point (T _m ), which is soon before the thermoplastic polyurethane particles are melted. It means that it has the characteristic of heating. According to one embodiment of the present invention, the cold crystallization temperature (T _cc ) appears in the 30% to 70% section between the glass transition temperature (T _g ) and the melting point (T _m ). In this section, 0% is the glass transition temperature (T _g ), and 100% is the melting point (T _m ). Further, according to the DSC curve, the thermoplastic polymer particles may have a difference (ΔH1-ΔH2) value of 3 to 100 J / g between an endothermic amount (ΔH1) and a calorific value (ΔH2). Due to this feature, when the thermoplastic polyurethane particles are utilized in a heating process, it is possible to obtain an advantage that processing is possible at a low temperature compared to the processing temperature of the same type of thermoplastic polyurethane particles.

The thermoplastic polyurethane particles of the present invention have a higher degree of compression than conventional thermoplastic polyurethane particles. The compressibility may be calculated by the following Equation 4, according to an embodiment of the present invention, the thermoplastic polyurethane particles have a compressibility of 7 to 15%.

[Calculation formula 4]

Compression degree = (P-R) / P × 100

In the above equation 4, P means compressed bulk density, and R means relaxed bulk density.

As described above, since the thermoplastic polyurethane particles according to the present invention have good flowability, they can fill the voids between the particles, and accordingly, they have a higher compressive value than the thermoplastic polyurethane particles produced by other manufacturing methods. maintain. The degree of compression of the thermoplastic polyurethane particles can affect the quality of the product when manufacturing the product through the particles. In the case of using thermoplastic polyurethane particles having a degree of compression or higher as in the present invention, in the case of a molded article, it may have an effect of minimizing voids that may occur in the product, and in the case of products such as cosmetics, between the skin and the product The compressibility can be improved. According to one embodiment of the present invention, the thermoplastic polyurethane particles have a compressed bulk density of 0.4 to 0.45 g / cm ³ . The compressed bulk density has a lower numerical value than the thermoplastic polyurethane particles produced by another manufacturing method, which is a constant between the particles of the thermoplastic polyurethane particles according to the present invention having a high sphericity and uniform particle size distribution after compression This is because it can have pores of size.

The thermoplastic polyurethane particles according to the present invention have a flow time of 10 to 20 seconds. The flow time is a numerical value indicating the fluidity of the powder. The short flow time means that there is little frictional resistance between particles, and if the frictional resistance between particles is small, it is easy to handle the particles. The thermoplastic polyurethane particles according to the present invention can maintain an appropriate level even in terms of the flow time, and the particles are easily handled in applying the particles.

The thermoplastic polyurethane particles having the above-described characteristics are produced by the following manufacturing method. Hereinafter, a method of manufacturing the thermoplastic polyurethane particles according to the present invention will be described in detail.

Manufacturing method of thermoplastic polyurethane particles

2 schematically shows a process flow chart for the manufacturing method. The manufacturing method comprises the steps of extruding by supplying a thermoplastic polyurethane resin to the extruder (S100); Supplying the extruded thermoplastic polyurethane resin and air to the nozzle, making the thermoplastic polyurethane resin granulate by contacting the thermoplastic polyurethane resin with air, and discharging the granulated thermoplastic polyurethane resin (S200); And supplying the discharged thermoplastic polyurethane particles to a cooler to cool the thermoplastic polyurethane particles, and then obtaining the cooled thermoplastic polyurethane particles (S300). Hereinafter, each step of the manufacturing method will be described in detail.

In order to manufacture thermoplastic polyurethane particles according to the present invention, first, a thermoplastic polyurethane resin as a raw material is supplied to an extruder and extruded. By extruding the thermoplastic polyurethane resin, the thermoplastic polyurethane resin has properties suitable for particle processing in the nozzle. The thermoplastic polyurethane resin used as a raw material may have a weight average molecular weight (Mw) of 10,000 to 200,000 g / mol in consideration of proper physical properties of the produced particles.

The extruder to which the thermoplastic polyurethane resin is supplied adjusts physical properties such as viscosity of the thermoplastic polyurethane resin by heating and pressing the thermoplastic polyurethane resin. The type of the extruder is not particularly limited as long as it can be adjusted to a property suitable for granulation in a nozzle. According to one embodiment of the present invention, the extruder may be a twin screw extruder for efficient extrusion. The interior of the extruder may be preferably maintained at 150 to 300 ° C, preferably 170 to 270 ° C, more preferably 200 to 250 ° C. When the internal temperature of the extruder is less than 150 ° C, the viscosity of the thermoplastic polyurethane resin is high, which is not suitable for granulation in the nozzle, and the flowability of the thermoplastic polyurethane resin in the extruder is low, which is not efficient for extrusion. In addition, if the internal temperature of the extruder exceeds 300 ° C, the flowability of the thermoplastic polyurethane resin is high, so that efficient extrusion is possible, but it is difficult to control fine physical properties when the thermoplastic polyurethane resin is granulated at the nozzle.

The extrusion amount of the thermoplastic polyurethane resin can be easily set to control the properties of the thermoplastic polyurethane resin in consideration of the size of the extruder. According to one embodiment of the invention, the thermoplastic polyurethane resin is extruded at a rate of 1 to 10kg / hr. The viscosity of the extruded thermoplastic polyurethane resin may be 0.5 to 20 Pa · s, preferably 1 to 15 Pa · s, and more preferably 2 to 10 Pa · s. When the viscosity of the thermoplastic polyurethane resin is less than 0.5 Pa · s, it is difficult to process particles at the nozzle, and when the viscosity of the thermoplastic polyurethane resin exceeds 20 Pa · s, the flow efficiency of the thermoplastic polyurethane resin at the nozzle is low, resulting in poor processing efficiency. The temperature of the extruded thermoplastic polyurethane resin may be 150 to 250 ℃.

The thermoplastic polyurethane resin extruded from the extruder is supplied to the nozzle. Along with the thermoplastic polyurethane resin, air is also supplied to the nozzle. The air is in contact with the thermoplastic polyurethane resin in the nozzle to granulate the thermoplastic polyurethane resin. In order to properly maintain the properties of the thermoplastic polyurethane resin, hot air is supplied to the nozzle. According to one embodiment of the present invention, the temperature of the air may be 250 to 450 ° C, preferably 260 to 400 ° C, more preferably 270 to 350 ° C. When the temperature of the air is less than 250 ° C or more than 450 ° C, when the thermoplastic polyurethane particles are produced in the thermoplastic polyurethane resin, the properties of the surface in contact with the air can be changed in an undesirable direction, which is a problem. In particular, when the temperature of the air exceeds 450 ° C, excessive heat is supplied to the contact surface with the air, so that the decomposition phenomenon of the thermoplastic polyurethane may occur on the surface of the particles.

The thermoplastic polyurethane resin and air supplied to the nozzle are set in a supply position so that the thermoplastic polyurethane particles can have an appropriate size and shape, and the formed particles are evenly dispersed. Figure 3 shows a cross-sectional view of the nozzle discharge portion, the supply position of the thermoplastic polyurethane resin and air according to an embodiment of the present invention will be specifically described through FIG. For the detailed description in this specification, the position of the nozzle is expressed as “injection part”, “discharge part”, and “end part”. The “injection part” of the nozzle means the position where the nozzle starts, and the “discharge part” of the nozzle means the position where the nozzle ends. Also, the “end portion” of the nozzle means the position from the two-thirds point of the nozzle to the discharge portion. Here, the zero point of the nozzle is the injection portion of the nozzle, and the one point of the nozzle is the discharge portion of the nozzle.

3, the cross section perpendicular to the flow direction of the thermoplastic polyurethane resin and air is circular. The air is supplied through the first air stream 40 supplied to the center of the circle and the second air stream 20 supplied to the outer portion of the circle, and the thermoplastic polyurethane resin is the first air stream 40 And a second air stream (20). Each supply flow (thermoplastic polyurethane resin flow 30, first air flow 40, and second air flow 20) from when the thermoplastic polyurethane resin and air are supplied to the injection portion of the nozzle to immediately before the discharge portion of the nozzle ) Is separated by the structure inside the nozzle. Just before the discharge portion of the nozzle, the flow of the thermoplastic polyurethane resin and the second air flow are brought into contact with the thermoplastic polyurethane resin, whereby the thermoplastic polyurethane resin is granulated. Alternatively, the first air stream is separated from the thermoplastic polyurethane resin stream and the second air stream by the nozzle inner structure until the thermoplastic polyurethane resin and air are discharged from the nozzle. The first air flow prevents particles of the thermoplastic polyurethane resin granulated by the second air flow from adhering at the discharge portion of the nozzle, and distributes the discharged particles evenly before being supplied to the cooler after discharge from the nozzle. do.

The thermoplastic polyurethane resin extruded from the extruder is all supplied to the above-described position of the nozzle, and the flow rate of air supplied to the nozzle can be adjusted according to the flow rate of the extruded thermoplastic polyurethane resin. According to one embodiment of the present invention, the air is supplied to the nozzle at a flow rate of 1 to 300 m ³ / hr, preferably 30 to 240 m ³ / hr, more preferably 60 to 180 m ³ / hr. Within the flow rate range of the air, air is supplied separately to the first air flow and the second air flow. As described above, the thermoplastic polyurethane resin is granulated by the second air flow, and the ratio of the thermoplastic polyurethane resin and the second air flow as well as the temperature of the second air flow can determine the physical properties of the particles. According to one embodiment of the present invention, the ratio of the cross-sectional area of the thermoplastic polyurethane resin and the second air stream based on the cross-section of the discharge portion of the nozzle may be 4: 1 to 6: 1, preferably 4.3: 1 to 5: 1. have. When the ratio of the thermoplastic polyurethane resin and the second air flow is controlled within the above range, it is possible to manufacture thermoplastic polyurethane particles of a suitable size and shape with high utility in 3D printing products and color cosmetics.

Since the thermoplastic polyurethane resin is granulated in the nozzle, the inside of the nozzle is adjusted to a temperature suitable for granulating the thermoplastic polyurethane resin. Since the rapid increase in temperature can change the structure of the thermoplastic polyurethane, the temperature from the extruder to the discharge portion of the nozzle can be increased step by step. Therefore, the internal temperature of the nozzle is set on average to a range higher than the internal temperature of the extruder. Since the temperature for the distal end of the nozzle is defined separately below, the internal temperature of the nozzle in this specification means the average temperature of the rest of the nozzle except the distal end of the nozzle, unless otherwise specified. According to one embodiment of the invention, the interior of the nozzle may be maintained at 250 to 350 ℃. When the internal temperature of the nozzle is less than 250 ° C, sufficient heat for satisfying physical properties is not transmitted to the thermoplastic polyurethane resin, and when the internal temperature of the nozzle is greater than 350 ° C, excessive heat is supplied to the thermoplastic polyurethane resin to give the thermoplastic poly The structure of urethane can be changed.

The distal end of the nozzle can be maintained at a temperature above the average temperature inside the nozzle to improve the external and internal properties of the resulting particles. The temperature at the distal end of the nozzle may be determined between the glass transition temperature (T _g ) and the thermal decomposition temperature (T _d ) of the thermoplastic polyurethane, and may be specifically determined according to the following Equation 5.

[Calculation formula 5]

Terminal temperature = glass transition temperature (T _g ) + (pyrolysis temperature (T _d ) -glass transition temperature (T _g )) × B

Here, B may be 0.5 to 1.5, preferably 0.65 to 1.35, and more preferably 0.8 to 1.2. When the B is less than 0.5, it is difficult to expect improvement in the external and internal properties of particles due to the temperature rise at the end of the nozzle, and when the B is more than 1.5, the heat substantially transferred to the thermoplastic polyurethane at the end of the nozzle is excessively increased. Thus, the structure of the thermoplastic polyurethane may be modified. The glass transition temperature and thermal decomposition temperature may vary depending on the type of polymer, polymerization degree, structure, and the like. According to one embodiment of the present invention, the thermoplastic polyurethane of the present invention has a glass transition temperature of -40 to -20 ℃, a thermoplastic polyurethane having a thermal decomposition temperature of 250 to 350 ℃ may be used. Since the distal end of the nozzle is maintained above the average temperature of the nozzle, in some cases, the distal end of the nozzle may be provided with additional heating means.

The thermoplastic polyurethane particles discharged from the nozzle are supplied to a cooler. The nozzle and the cooler can be positioned spaced apart, in which case the discharged thermoplastic polyurethane particles are primarily cooled by ambient air before being fed to the cooler. In the nozzle, not only the thermoplastic polyurethane particles, but also hot air is discharged together. By separating the nozzle from the cooler, the hot air can be discharged outside the cooler, so that the cooling efficiency can be increased in the cooler. According to one embodiment of the present invention, the cooler is positioned 100 to 500 mm away from the nozzle, preferably 150 to 400 mm, more preferably 200 to 300 mm apart. When the separation distance is shorter than the above distance, a large amount of high temperature air is injected into the cooling chamber to reduce the cooling efficiency, and when the separation distance is longer than the above distance, the amount cooled by the surrounding air increases and rapid cooling by the cooling chamber This is not done. In addition, when discharging the thermoplastic polyurethane particles from the nozzle, the injection angle may be 10 to 60 °. When discharging the thermoplastic polyurethane particles at the corresponding angle, the effect of the separation between the nozzle and the cooler may be doubled.

The cooler may cool the thermoplastic polyurethane particles by supplying low-temperature air to the cooler to contact the air and the thermoplastic polyurethane particles. The low-temperature air forms a rotating airflow in the cooler, and the residence time of the thermoplastic polyurethane particles in the cooler can be sufficiently secured by the rotating airflow. The flow rate of the air supplied to the cooler may be adjusted according to the supply amount of the thermoplastic polyurethane particles, and according to an embodiment of the present invention, the air may be supplied to the cooler at a flow rate of 1 to 10 m ³ / min. The air may preferably have a temperature of -30 to -20 ℃. By supplying cryogenic air into the cooler in comparison to the thermoplastic polyurethane particles supplied to the cooler, the thermoplastic polyurethane particles are rapidly cooled, so that when discharged, the internal structure of the high temperature thermoplastic polyurethane particles can be properly maintained. When the thermoplastic polyurethane particles are actually applied for the production of a product, they are reheated again, where the reheated thermoplastic polyurethane has properties favorable for processing. The thermoplastic polyurethane particles cooled by low-temperature air are cooled and discharged below 40 ° C, and the discharged particles are collected through a cyclone or bag filter.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are provided only to more easily understand the present invention and the present invention is not limited thereto.

Example

Example  One

Thermoplastic polyurethane resin (Lubrizol, Pearlthane ^TM D91M80, Mw: about 160,000 _g / mol, glass transition temperature (T _g ): about -37 ° C, pyrolysis temperature (T _d ): about 290 ° C) twin screw extruder (Diameter (D) = 32 mm, length / diameter (L / D) = 40). The twin screw extruder was set at a temperature condition of about 220 ° C. and an extrusion amount condition of about 5 kg / hr to proceed with extrusion. The extruded thermoplastic polyurethane resin has a viscosity of about 5 Pa · s, and the extruded thermoplastic polyurethane resin has an internal temperature of about 300 ° C. and an end temperature of about 300 ° C. (B value according to calculation formula 5 is about 1.03). It was supplied to the set nozzle. In addition, air at about 350 ° C was supplied to the nozzle at a flow rate of about 1 m ³ / min. The air was supplied to the center and outer portion of the nozzle cross-section, and the extruded thermoplastic polyurethane resin was supplied between the center and the outer portion of the nozzle to which air was supplied. The cross-sectional area ratio of the air supplied to the outer portion and the extruded thermoplastic polyurethane supplied between the central portion and the outer portion supplied with air was about 4.5: 1. The thermoplastic polyurethane resin supplied to the nozzle was atomized by contact with hot air, and the atomized particles were sprayed from the nozzle. The injection angle from the nozzle was about 45 °, and the injected particles were supplied to a cooling chamber (diameter (D) = 1,100 mm, length (L) = 3,500 mm) spaced about 200 mm from the nozzle. In addition, the cooling chamber was adjusted to form a rotating airflow by injecting air at -25 ° C at a flow rate of about 6 m ³ / min from before the injected particles were supplied. Particles sufficiently cooled to below 40 ° C. in the cooling chamber were captured through a cyclone or bag filter.

Comparative example  One

Thermoplastic polyurethane particles were prepared in the same manner as in Example 1, except that the temperature of the end portion was adjusted to 124 ° C (the B value according to the calculation formula 5 is about 0.49).

Comparative example  2

Thermoplastic polyurethane particles were prepared in the same manner as in Example 1, except that the temperature of the end portion was adjusted to 470 ° C (the B value according to calculation formula 5 is about 1.55).

Comparative example  3

The same thermoplastic polyurethane resin as in Example 1 was fed through a hopper to a screw feeder. Water was removed while moving the raw material through a screw, and then the raw material was introduced into a grinder supplied with liquid nitrogen at -130 ° C. The crusher was a pin crusher type crusher. The particle size was controlled through a crush size pin. Particulate particles were collected through a cyclone through a cyclone.

Comparative example  4

Thermoplastic polyurethane particles were prepared in the same manner as in Example 1, except that the cross-sectional area ratio of the air supplied to the outer portion and the extruded thermoplastic polyurethane supplied between the center and the outer portion supplied with air was 3.5: 1.

Comparative example  5

Thermoplastic polyurethane particles were prepared in the same manner as in Example 1, except that the cross-sectional area ratio of the air supplied to the outer portion and the extruded thermoplastic polyurethane supplied between the central portion and the outer portion supplied with air was 6.5: 1.

Experimental Example  One

It is shown in Table 1 below by measuring the particle size distribution of the thermoplastic polyurethane particles prepared according to Example 1 and Comparative Examples 1 to 5. Specifically, the particle size distribution was measured by the following two steps.

1) Sample pretreatment: Put the powder sample in ethanol about 0.003wt%, set it to 30% of the maximum amplitude using an ultrasonic disperser of 50Watt / 30kHz, and disperse the powder sample on ethanol with ultrasonic waves for about 120 seconds.

2) Measurement of particle size distribution: Measure particle size distribution according to ISO 13320 standard.

Particle size distribution D ₁₀ (㎛) D ₅₀ (㎛) D ₉₀ (㎛) D Example 1 10 28 60 12.42 Comparative Example 1 550 800 1150 4.17 Comparative Example 2 1.2 8 16.5 48.73 Comparative Example 3 8 45 68 33.92 Comparative Example 4 195 232 325 3.38 Comparative Example 5 2.5 15 30.5 40.13

According to Table 1, the particle diameter of the particles prepared according to Example 1 is not biased in a direction large or small based on the average particle diameter, unlike the particle sizes of particles prepared according to Comparative Examples 2, 3 and 5, D ₅₀ You can see that the ratio of / D ₁₀ and D ₉₀ / D ₅₀ remains similar. In addition, the particle diameter of the particles produced according to Example 1 is not too large unlike the particle diameters of particles prepared according to Comparative Examples 1 and 4, and the ratio of D ₅₀ / D ₁₀ and D ₉₀ / D ₅₀ is higher than a certain level ( It can be seen that it is maintained at about 2 to 3).

When the particles have the same particle size distribution as the particles produced according to Example 1, it is possible to effectively compensate for the disadvantages of having only an average particle diameter when applied to a product.

Experimental Example  2

The physical properties of the particles prepared according to Example 1 and Comparative Example 3 were measured and are shown in Table 2 below.

Average particle diameter ^{1 )} (㎛) Aspect ratio ^{2 )} Sphericalization degree ^{3 )} Relaxed bulk density ^{4 )} (g / cm ³ ) Compressed bulk density ^{5 )} (g / cm ³ ) Compression degree ^{6 )} (%) Travel time ^{7 )} (s) Example 1 28 1.02 ± 0.02 0.98 ± 0.02 0.401 0.435 7.8 18 Comparative Example 3 45 1.44 ± 0.35 0.71 ± 0.25 0.45 0.46 2.2 21

1) Average particle diameter: D ₅₀ value is measured by the method of Experimental Example 2. 2), 3) Aspect ratio and spheroidization: Image processing using the same device-Converting to binary image and quantifying the degree of spheroidization of individual particles- The formation of the particles was analyzed, and the aspect ratio and degree of spheronization were derived by equations 2 and 3.

4) Relaxed bulk density: The mass per unit volume is calculated by measuring the mass when particles are quietly filled in a cylinder of 100 ml (average value measured 5 times repeatedly).

5) Compressed Bulk Density: After the cylinder filled with the particles is beaten 10 times with a constant force by 1), the mass is measured per mass to calculate the mass per unit volume (average value measured 5 times).

6) Compression degree (%) = (P-R) / P × 100, P: particle compression bulk density, R: particle relaxation bulk density.

7) Flow time: After filling particles in a cylinder of 100ml, pour it into the funnel of the apparent specific gravity measuring device of KS M 3002 and open the outlet to measure the time it takes for the sample to come out completely (average value measured 5 times).

According to Table 2, the particles of Example 1 have a small diameter and a uniform particle distribution compared to the particles of Comparative Example 3. In addition, the particles of Example 1 have a high degree of spheroidization compared to the particles of Comparative Example 3, whereby a certain space can be secured during compression and thus have a low compression bulk density. The particles of Example 1 may have an effect of minimizing voids that may occur in the product when used in a molded article while having low compression bulk density and high compression, and when used in products such as cosmetics, between the skin and the product The compressibility can be improved.

Experimental Example  3

Particles prepared according to Example 1 and Comparative Example 3 were analyzed by DSC and are shown in Table 3 below. Specifically, using a differential scanning calorimeter (DSC, Perkin-Elmer, DSC8000), the temperature was raised from 0 ° C to 200 ° C under a heating rate of 10 ° C / min to obtain a DSC curve. From each DSC curve, the difference between the glass transition temperature (T _g ), melting point (T _m ), cold crystallization temperature (T _cc ), and heat absorption (ΔH1) and calorific value (ΔH2) was derived.

T _g (℃) T _m (℃) T _cc (℃) △ H1- △ H2 (J / g) Example 1 -37 136 36 6 Comparative Example 3 -34 140 - -

It was confirmed that the thermoplastic polyurethane particles of Example 1 exhibited a cold crystallization temperature peak at 36 ° C, whereas the thermoplastic polyurethane particles of Comparative Example 3 did not exhibit such a cold crystallization temperature peak. Furthermore, in Example 1, it was confirmed that the difference between the endothermic amount (ΔH1) and the calorific value (ΔH2) was about 6 J / g.

When the thermoplastic polyurethane particles have a cold crystallization temperature peak as in Example 1, when heat-processing using these particles, it may have the advantage of being able to process at a low temperature compared to the processing temperature of the thermoplastic polyurethane particles of Comparative Example 3 .

All simple modifications or changes of the present invention belong to the scope of the present invention, and the specific protection scope of the present invention will become apparent by the appended claims.

d: the vertical distance of two parallel tangent planes
A: Area
10: nozzle
20: second air flow
30: thermoplastic polyurethane resin flow
40: first air flow

Claims (17)

It is formed in a continuous matrix from a thermoplastic polyurethane resin,
Thermoplastic polyurethane particles having a particle diameter of 1 to 100㎛.
The method according to claim 1,
The thermoplastic polyurethane particles are thermoplastic polyurethane particles, characterized in that having an average particle diameter (D ₅₀ ) of 20 to 50㎛.
The method according to claim 1,
The thermoplastic polyurethane particles have a cumulative volume of 5 to 15㎛ 10% particle diameter (D ₁₀ ) of the thermoplastic polyurethane particles.
The method according to claim 1,
The thermoplastic polyurethane particles have a cumulative volume of 40 to 80㎛ 90% particle diameter (D ₉₀ ), characterized in that the thermoplastic polyurethane particles.
The method according to claim 1,
The thermoplastic polyurethane particles are thermoplastic polyurethane particles, characterized in that the D value calculated by the following formula 1 is 5 to 20:

[Calculation formula 1]

Here, D ₁₀ is a cumulative volume 10% particle diameter, D ₅₀ is an average particle diameter, and D ₉₀ is a cumulative volume 90% particle diameter.
The method according to claim 1,
Thermoplastic polyurethane particles, characterized in that the impurity content of the thermoplastic polyurethane particles is 50ppm or less.
The method according to claim 1,
The thermoplastic polyurethane particles are cooled at a temperature between the glass transition temperature (T _g ) and the melting point (T _m ) in a DSC curve derived from an elevated temperature analysis of 10 ° C./min by differential scanning calorimetry (DSC). Thermoplastic polyurethane particles characterized in that the peak of the crystallization temperature (T _cc ) appears.
The method according to claim 1,
The thermoplastic polyurethane particles have an aspect ratio calculated by the following formula 2 is 1.00 or more and less than 1.05,
Thermoplastic polyurethane particles having a sphericity degree of 0.95 to 1.00 calculated by the following formula (3):

[Calculation formula 2]
Aspect ratio = major axis / minor axis

[Calculation formula 3]
Roundness = 4 × area / (π × long axis ^ 2).
The method according to claim 1,
The thermoplastic polyurethane particles are thermoplastic polyurethane particles, characterized in that the compression degree calculated by the following equation 4 is 7 to 15%:

[Calculation formula 4]
Compression degree = (compressed bulk density-relaxed bulk density) / compressed bulk density × 100.
The method according to claim 9,
The thermoplastic polyurethane particle is a thermoplastic polyurethane particle, characterized in that it has a compressed bulk density of 0.4 to 0.45g / cm ³ .
The method according to claim 1,
The thermoplastic polyurethane particles are thermoplastic polyurethane particles, characterized in that having a flow time of 10 to 20 seconds.
A method for producing a thermoplastic polyurethane particle according to claim 1,
The manufacturing method,
(1) supplying a thermoplastic polyurethane resin to the extruder to extrude;
(2) supplying the extruded thermoplastic polyurethane resin and air to the nozzle, contacting the thermoplastic polyurethane resin with air to granulate the thermoplastic polyurethane resin, and then discharging the granulated thermoplastic polyurethane resin; And
(3) A method of manufacturing a thermoplastic polyurethane particle comprising supplying the discharged thermoplastic polyurethane particle to a cooler to cool the thermoplastic polyurethane particle, and then obtaining the cooled thermoplastic polyurethane particle.
The method according to claim 12,
The method for producing thermoplastic polyurethane particles, characterized in that the extruded thermoplastic polyurethane resin supplied to the nozzle in step (2) has a melt viscosity of 0.5 to 20 Pa · s.
The method according to claim 12,
Based on the cross-section of the nozzle in step (2), air is supplied to the central portion and the outer portion, and the extruded thermoplastic polyurethane resin is supplied between the central portion and the outer portion to which air is supplied. Manufacturing method.
The method according to claim 14,
In the step (2), the ratio of the cross-sectional area of the extruded thermoplastic polyurethane resin supplied between the air supplied to the outer portion and the central portion and the outer portion to which the air is supplied is 4: 1 to Method of producing a thermoplastic polyurethane particles, characterized in that 6: 1.
The method according to claim 12,
The method of manufacturing the thermoplastic polyurethane particles, characterized in that the inside of the nozzle in step (2) is maintained at 250 to 350 ℃.
The method according to claim 16,
The method of manufacturing a thermoplastic polyurethane particle characterized in that the discharge portion of the nozzle in step (2) is maintained at a temperature calculated by the following Equation 5:

[Calculation formula 5]
Discharge temperature = glass transition temperature (T _g ) + (decomposition temperature (T _d ) -glass transition temperature (T _g )) × B

In the calculation formula 5, the glass transition temperature and decomposition temperature are values for the thermoplastic polyurethane, and B is 0.5 to 1.5.

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