KR101011787B1 - A shape memory polyurethane electrospun web and method for preparation of the same - Google Patents

Abstract

The present invention relates to a process for the preparation of poly (ε-caprolactone diol) (PCL), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4- To prepare a polyurethane; (b) dissolving the polyurethane in a solvent mixed with N, N-dimethylformamide (DMF) and tetrahydrofuran (THF) in a ratio of 6: 4 to 4: 6 (v / v) Preparing a polyurethane solution for room use; And (c) 4 to 7% by weight of an electrospun polyurethane solution is electrospun under the conditions of a voltage of 6 to 16 kV, a radiation distance of 5 to 20 cm and a discharge amount of 1.0 to 2.5 ml / A method of making a shape memory polyurethane electrospun web comprising the steps of: obtaining a urethane emissive web; And a shape memory polyurethane electrospun web made according to this method.

The shape memory polyurethane electrospun web according to the present invention is excellent in thermal performance, comfort performance (air permeability, moisture permeability, warmth, etc.) and exhibits superior heat resistance particularly in a high temperature and dry environment. And the like.

Polyurethane, polyol, poly (ε-caprolactone diol), 4,4'-diphenylmethane diisocyanate, 1,4-butanediol, N, N-dimethylformamide, tetrahydrofuran , Voltage, radiation distance, discharge amount, transition temperature, pore, heat insulation, breathability, moisture permeability.

Description

TECHNICAL FIELD [0001] The present invention relates to a shape memory polyurethane electrospun web, and a method of manufacturing the same. More particularly, the present invention relates to a shape memory polyurethane electrospun web,

The present invention relates to a shape memory polyurethane electrospun web and a method of manufacturing the same. More specifically, the present invention relates to a method of synthesizing a shape memory polyurethane by controlling the molecular weight of a polyol, the kind and ratio of a solvent, and then synthesizing a shape memory polyurethane by electrospinning under optimal conditions (solution concentration, voltage, A method of producing a shape memory polyurethane electrospun web excellent in not only an optimal shape memory effect but also excellent thermal performance, pleasant performance (air permeability, moisture permeability, warmth, etc.); And a shape memory polyurethane electrospun web produced by this method.

In addition to the rapid development of nanotechnology in high-tech industries, much interest has been focused on the manufacture of nanofibers having a diameter of several nanometers to several hundreds of nanometers in the field of fibers. In particular, It has attracted attention.

Electrospinning can produce fibers of various diameters according to various radiation conditions such as the intensity of the voltage, the distance and angle between the syringe tip and the collector, the amount of solution discharged, the radiation temperature / humidity, The equipment is comparatively simple and applicable to a wide range of polymer materials. Nanofiber materials made by electrospinning have resistance to the transmission of fine particles by nano-sized pores. In addition, it has various advantages such as breathability that can exhaust the sweat of the inner structure structurally, waterproof and windproof effect outside the film, and air entrapment due to high air content.

'Shape storage material' means a material capable of recovering from its original shape temporarily stored by external stimuli. As such shape memory materials, shape memory alloys and shape memory polymers (polymers) are known. The 'shape memory effect' means that the shape memory material does not return to its original shape when the shape memory material is made to form at an arbitrary shape at high temperature and is then cooled and then deformed at low temperature. However, It means the effect of going. Shape memory effect may occur in response to heat, or may be caused by light or chemical reaction. Shape memory polymers (eg, polynorbornene, poly (isoprene-butadiene-styrene, polyurethane, polystyrene, etc.) are lighter than shape memory alloys, have a higher shape memory recovery rate, are easier to process, The shape memory polymer is structurally composed of a two-phase structure in which softening and hardening can be reversibly reversed by fixing points and temperature changes that interfere with the flow of the polymer It is possible to recover the residual strain at the time of temperature rise.

Shape memory polyurethanes are block copolymers composed of two different segments. These two segments have a structure separated by a soft segment and a hard segment due to the thermodynamic incompatibility. The physical properties of the polyurethane depend on the degree of phase separation and phase separation of the two segments. The soft segment has a low glass transition temperature (Tg) or a low melting point (Tm) and is in a non-oriented state of the random coil in the normal relaxed state due to its abundant flexibility. The hard segment forms a rigid crystal lattice due to the interaction between the strong hydrogen bonds between the urethane bonds and the plane structure between the benzene rings to form a three-dimensional network structure by physical crosslinking. Therefore, when the polyurethane is stretched by forming a discontinuous phase, slip between the molecular chains is prevented, thereby imparting stability, elasticity, etc. to the polyurethane. When stretched, the molecular chains of the soft segments in the random coil state are elongated as they become linear. When the stretching force is removed, the soft segments are returned to the original length by the entropy elasticity.

The shape memory polyurethane has a glass transition temperature (T _{g, hard} ) of the _hard segment higher than a glass transition temperature (T _{g, soft} ) of the soft segment. Polyurethane is most active in all polymer chains at temperatures above the melting point (T _{m, hard} ). When it is cooled to the glass transition temperature (T _{g, hard} ) of the hard segment, the shape of the hard segment is stored by physical crosslinking. However, the shape of the hard segment is stored between the soft segment's glass transition temperature (T _{g, soft} ) and the hard segment's glass transition temperature (T _{g, hard} ), but the soft segment has a glass transition temperature (T _{g, soft} ) Or more, so that it can be deformed into a temporary shape due to its fluidity. Below the glass transition temperature (T _{g, soft} ) of the soft segment, the soft segment is completely in the glassy state and the deformed shape remains fixed even when the external force is removed. If the soft segment is again raised above the glass transition temperature (T _{g, soft} ) of the soft segment, the soft segment is free to move and is restored to its original length by entropy elasticity. As the physical cross-linking of the hard segment is released, the memorized shape of the polymer is erased.

In the case of a polyurethane mainly used as a shape memory polymer, since the glass transition temperature of the soft segment is very low, in order to exhibit the shape memory effect near room temperature, the molecular weight of the soft segment or the ratio of the hard segment to the soft segment is adjusted, There was an attempt to raise it to the vicinity, but there were many difficulties.

The inventors of the present invention have conducted intensive studies and have found that PCL, which exhibits a transition temperature at a melting point (T _{m, soft} ) of a soft segment and exhibits at room temperature or higher, is used as a polyol. By controlling the molecular weight, Urethane is synthesized and then electrospun under optimal conditions (concentration of solution, voltage, radial distance, amount of solution discharged, etc.), not only the optimal shape memory effect is manifested, but also thermal performance and comfort performance , Warmth, etc.), and so on. Based on this, it is expected to be applied to intelligent protective clothing or sportswear with protective function.

The present invention provides a shape memory polyurethane electrospun web excellent in thermal performance, comfort performance (air permeability, moisture permeability, warmth, etc.) and a method for manufacturing the same, as well as exhibiting an optimal shape memory effect, So that it can be expected to be applied to intelligent protective clothing or sportswear.

The present invention relates to a process for producing a shape memory polyurethane electrospun web, comprising the steps of: (a) reacting poly (ε-caprolactone diol) (PCL), 4,4'-diphenylmethane diisocyanate (MDI) BD) at a molar ratio of 1: 2 to 6: 1 to 5 to synthesize a polyurethane; (b) dissolving the polyurethane in a solvent mixed with N, N-dimethylformamide (DMF) and tetrahydrofuran (THF) in a ratio of 6: 4 to 4: 6 (v / v) Preparing a polyurethane solution for room use; And (c) 4 to 7% by weight of an electrospun polyurethane solution is electrospun under the conditions of a voltage of 6 to 16 kV, a radiation distance of 5 to 20 cm and a discharge amount of 1.0 to 2.5 ml / Wherein the polyurethane emissive web is a polyurethane emissive web.

In the step (a), the molecular weight (Mw) of the poly (? -Caprolactone diol) (PCL) is preferably 2500 to 4500, more preferably 3000 to 4000, and most preferably 4000. In addition, when poly (ε-caprolactone diol) (PCL), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) are mixed at a molar ratio of 1: (PCL), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) having a molecular weight of 4000 in a ratio of 1: 6: 5 Mixing is most preferred.

In the polyurethane synthesized in the step (a), the ratio of the content of the hard segment to the content of the soft segment is preferably 75 to 95: 5 to 25, most preferably 92: 8 Do.

The solvent used in step (b) is preferably 6: 4 to 4: 6 (v / v), most preferably 5: 5 (v / v). When the DMF is used alone, the volatility of the solvent is low, and the state of the web collected on the collector during electrospinning is not good. Therefore, by mixing the DMF and THF in the above ratio, Of the web.

 In step (c), 4 to 7 wt% of the polyurethane solution for electrospinning is electrospun under the conditions of a voltage of 6 to 16 kV, a radiation distance of 5 to 20 cm and a discharge amount of 1.0 to 2.5 ml / hour. More preferably, 4 to 7% by weight of the polyurethane solution for electrospinning is electrospun under the conditions of a voltage of 9 to 16 kV, a radiation distance of 14 to 16 cm and a discharge amount of 1.0 to 2.0 ml / hour. Thereby, an optimal shape memory polyurethane electrospun web can be obtained.

The present invention also provides a shape memory polyurethane electrospun web produced by the above-described method.

The shape memory polyurethane electrospun web according to the present invention has a pore size of 144 to 553 nm when it is in a steady state and a pore size of 153 to 807 nm when it is immobilized by elongating 50% The size of the pores is 149 to 605 nm.

The shape memory polyurethane electrospun web of the present invention has a transition temperature (T _trans ) of More preferably 35 to 40 占 폚, and still more preferably 38 to 39 占 폚.

The shape memory polyurethane electrospun web according to the present invention preferably has a shape recovery of 90% or more, more preferably 95% or more.

The shape memory polyurethane emissive web according to the present invention has a transmittance of 9 to 10 cm 3 / cm 2 / s when the air permeability measured by the ASTM D737 method is steady, and 30 cm 3 / cm 2 / / Cm < 2 > / s or more. The moisture permeability of the shape memory polyurethane electrospun web measured by ASTM E96 method was increased from 2000 to 2400 g / m 2/24 hours to 5800 to 5900 g / m 2/24 hours when the temperature was raised from 20 ° C to 40 ° C Being; The internal water of the shape memory polyurethane electrospun web measured by the ISO 811 method is preferably 30 to 80 cmWC.

The shape-memory polyurethane electrospun web according to the present invention has a high temperature and high humidity environment (relative humidity (RH): 10%, temperature: 20 ° C -> 30 ° C -> 40 ° C) Temperature: 20 占 폚 - 30 占 폚 - 40 占 폚], it is preferable that the temperature difference?

The shape memory polyurethane electrospun web according to the present invention is excellent in thermal performance, comfort performance (air permeability, water resistance, warmth, etc.), and exhibits superior heat resistance particularly in a high temperature and dry environment. And the like.

The following examples further illustrate the present invention. However, the following examples are intended to illustrate the present invention, and the scope of the present invention should not be construed as being limited to the following examples. Accordingly, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Example

Preparation of polyurethane solution for electric room use

(PCL) having a molecular weight of 4000, 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) in a molar ratio of 1: 6: Polyurethane having a ratio of the segment content to the soft segment content of 92: 8 was synthesized. Subsequently, the polyurethane was dissolved in a solvent in which N, N-dimethylformamide (DMF) and tetrahydrofuran (THF) were mixed at a ratio of 5: 5 (v / v) Was prepared.

Electrospinning under optimal conditions

We tried to find the optimum electrospinning condition by changing the concentration of polyurethane solution for electric room and finding the concentration range suitable for electrospinning and adjusting the voltage, radiation distance [distance between syringe tip and collector] and the amount of solution discharge.

The electrospinning conditions were adjusted while varying the concentration of the polyurethane solution from 4 wt% to 8 wt%. As a result of observing the voltage while controlling the electrospun web of 4 wt% solution, it was confirmed that electrospinning was possible at 6 kV. Electrospinning was started at 7 kV, 9 kV, 10 kV, and 11 kV at 5 wt%, 6 wt%, 7 wt%, and 8 wt%, respectively. As the concentration of the solution increased, . The optimal voltages for the solutions were 9, 10, 14, and 16 kV at 4 wt%, 5 wt%, 6 wt%, and 7 wt%, respectively. The most uniform and stable web ). At a voltage lower than the optimum voltage of the solution, the web was not uniform, and some agglomerated state appeared. At higher voltages than the optimum voltage, the solution splashed or beads were formed on the web. It has been confirmed that the beads generated from the electrospun web have a major influence on the voltage, and the formation of the beads also varies depending on the concentration of the solution and the type of the solvent.

The optimum amount of the solution according to the concentration of the solution was 1.0 ml / hr, 1.5 ml / hr, 2.0 ml / hr and 2.0 ml / hr in the solutions of 4 wt%, 5 wt%, 6 wt% and 7 wt%, respectively. When electrospinning at an appropriate voltage according to the concentration of the solution, if the amount of the solution discharged becomes large, all of the discharged solution in the course of collecting the electrospun solution on the collector on the web does not form a web, Shape. This was more prominent when the 4 wt% solution with low viscosity was electrospun.

The distance between the syringe tip and the collector was adjusted in the range of 10-20 cm. In the case of 10 cm, the amount of fibers collected in the collector was large, but the amount of the splashing solution was increased by the voltage, . Therefore, the distance between the syringe tip and collector was selected to be about 15 cm.

On the other hand, the solution of 8 wt% or more showed a sharp increase in viscosity, which was radiated in a very thick and non-uniform form and appeared to be a concentration unsuitable for electrospinning.

Performance of shape memory polyurethane electrospun web

Experiments were conducted on the performance of a shape memory polyurethane electrospun web formed by spinning under the optimum conditions mentioned above.

● Transition temperature (T _trans )

The thermal behavior of the shape memory polyurethane electrospun web was measured using differential scanning calorimetry (DSC). The shape memory polyurethane electrospun web showed an endothermic peak at 38.16 ° C. In addition, the curve shows a more inclined curve in the endo direction of the heat flow as the temperature rises continuously. In particular, nanofibers have been found to have better crystallization and orientation in the process of forming the nanoweb, and thus have higher transition temperature and higher heat of fusion.

● Shape memory effect

Shape memory polyurethane electrospun web showed shape recovery of more than 95% due to orientation development of hard segment. However, since the shape memory polyurethane electrospun web has a nano-sized thin fibrous mesh structure, the shape retention is relatively low at 66%.

● Pore (气 孔)

The shape memory polyurethane electrospun web had an average pore diameter of 346 nm in the steady state and an average pore diameter of 478 nm in the case of immobilization with 50% elongation in both directions. The average pore diameter was 382 nm .

● Air permeability, moisture and water resistance

The shape memory polyurethane electrospun web was 9.5 cm 3 / cm 2 / s when the air permeability measured by the ASTM D737 method was steady, and 30 cm 3 / cm 2 / s or greater when immobilized by 50% stretching in both directions .

The water vapor transmission rate measured by the ASTM E96 method was increased from 2000 to 2400 g / m 2/24 hours to 5800 to 5900 g / m 2/24 hours when the temperature was raised from 20 ° C to 40 ° C. When the elongated electrospun web is immobilized by 50% elongation in both directions, the increase of the pore size and the increase of the vapor pressure due to the temperature rise show a synergistic effect of the water vapor permeability. However, Since it restores more than 95% while shrinking to the original shape, it does not show a large difference from the electroluminescent web not stretched at 40 캜.

On the other hand, the internal capacity of the shape memory polyurethane electrospun web measured by the ISO 811 method was relatively low in the range of 30 to 80 cm WC. However, it was thought that if we fabricated the actual fabric with the bottom fabric together, we could greatly improve our water supply.

● Train building

The apparatus for evaluating thermal resistance as shown in Fig. 5 was used to evaluate thermal resistance in a high temperature and high humidity and high temperature drying environment.

The inside of the chamber and the inside of the insulating box were kept at the same temperature and a relative humidity (RH) of 65% at a temperature of 20 ° C, then the relative humidity (RH) of the chamber was maintained at 65%, the temperature was raised to 30 ° C and 40 ° C The change in the temperature inside the insulation box was measured. The temperature difference (ΔT) when the insulation box was shut off when it was heated to 30 ℃ and when it was not blocked was about 2 ℃ maximum. In addition, when the temperature was raised to 40 ° C, the temperature difference (ΔT) when the insulating box was shut off and when it was not shut off was about 4 ° C at the maximum.

 The inside of the chamber and the inside of the insulating box were kept at the same temperature of 20 ° C and relative humidity (RH) of 65%, and then the relative humidity (RH) of the chamber was lowered from 65% to 10% Lt; RTI ID = 0.0 > C, < / RTI > The temperature difference (ΔT) when the insulation box was shut off when it was heated to 30 ℃ and when it was not blocked was about 2.5 ℃. In addition, when the temperature was raised to 40 ° C, the temperature difference (ΔT) when the insulating box was shut off and when it was not shut off was about 4 ° C at the maximum.

Therefore, it was confirmed that the shape memory polyurethane electrospun web has the ability to block heat from the outside in an active and aggressive manner while maintaining the moisture permeability by controlling the pore size according to the ambient temperature. In particular, it has superior thermal performance in a high temperature and dry environment. Therefore, it is expected that it can be widely applied to sportswear or fire wall of extreme environment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram for manufacturing a shape memory polyurethane electrospun web of the present invention. FIG.

Figure 2 is a typical stress-strain curve for shape memory effect measurements.

Fig. 3 shows a device for evaluating thermal resistance.

4 shows a system for controlling the temperature and humidity inside the chamber of the apparatus shown in FIG.

Fig. 5 is an enlarged view of a video microscope image at 600 times magnification at optimal conditions of various concentrations of shape memory polyurethane solutions.

6 is a graph showing the relationship between optimum voltage and heat flow of shape memory polyurethane solutions at various concentrations.

7 is a scanning electron micrograph of a shape memory polyurethane electrospun web prepared by electrospinning 4 wt% of a shape memory polyurethane solution under optimal conditions at 2000 times magnification.

8 is a graph showing the pore diameter distribution of the shape memory polyurethane electrospun web.

9 is a graph showing the air permeability of the sample.

10 is a graph showing the moisture permeability of the shape memory polyurethane electrospun web according to the temperature.

11 is a graph showing the internal resistance of the sample.

12 is a graph showing the thermal shock resistance of a sample at a temperature of 30 캜 and a relative humidity (RH) of 65%.

13 is a graph showing the thermal conductivity of the sample at a temperature of 40 DEG C and a relative humidity (RH) of 65%.

14 is a graph showing the thermal resistance of the sample at a temperature of 30 DEG C and a relative humidity (RH) of 10%.

15 is a graph showing the thermal conductivity of a sample at a temperature of 40 DEG C and a relative humidity (RH) of 10%.

Claims (12)

(a) poly (ε-caprolactone diol) (PCL), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) in a molar ratio of 1: 2 to 6: Synthesizing a polyurethane by mixing; (b) dissolving the polyurethane in a solvent mixed with N, N-dimethylformamide (DMF) and tetrahydrofuran (THF) in a ratio of 6: 4 to 4: 6 (v / v) Preparing a polyurethane solution for room use; And (c) 4 to 7% by weight of an electrically conductive polyurethane solution is electrospun under conditions of a voltage of 6 to 16 kV, a radiation distance of 5 to 20 cm and a discharge amount of 1.0 to 2.5 ml / And a step of obtaining an electrospun web. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 1, Wherein the poly (ε-caprolactone diol) (PCL) has a molecular weight of 2500 to 4500. The method according to claim 1, Wherein the polyurethane synthesized in the step (a) has a ratio of a content of a hard segment to a content of a soft segment of 75 to 95: 5 to 25, A method of manufacturing a web. The method according to claim 1, Wherein a solvent in which N, N-dimethylformamide (DMF) and tetrahydrofuran (THF) are mixed in a ratio of 5: 5 (v / v) is used in the step (b) A method of manufacturing a spinning web. The method according to claim 1, In the step (c), 4 to 7% by weight of the polyurethane solution for use in electrospinning is electrospun under the conditions of a voltage of 9 to 16 kV, a radiation distance of 14 to 16 cm and a discharge amount of 1.0 to 2.0 ml / Wherein the shape memory polyurethane emissive web is formed by a method comprising the steps of: A shape memory polyurethane electrospun web produced according to the method of any one of claims 1 to 5. The method according to claim 6, The shape-memory polyurethane electrospun web had pore sizes of 144 to 553 nm in a steady state and pore sizes of 153 to 807 nm when they were immobilized by stretching 50% in both directions in both directions, Wherein the size of the polyurethane emissive layer is from 149 to 605 nm. The method according to claim 6, The transition temperature (T _trans ) of the shape memory polyurethane electrospun web is Lt; RTI ID = 0.0 > 35-40 C. < / RTI > The method according to claim 6, Wherein the shape recovery of the shape memory polyurethane electrospun web is greater than 90%. The method according to claim 6, The air permeability of the shape memory polyurethane electrospun web measured by the ASTM D737 method was 9 to 10 cm3 / cm2 / s in a steady state and 30 cm3 / cm2 / lt; RTI ID = 0.0 > p < / RTI > The method according to claim 6, The moisture permeability of the shape memory polyurethane electrospun web measured by the ASTM E96 method is increased from 2000 to 2400 g / m 2/24 hr to 5800 to 5900 g / m 2/24 hr when the temperature is raised from 20 ° C to 40 ° C; Wherein the internal memory of the shape memory polyurethane electrospun web measured by the ISO 811 method is 30-80 cm WC. The method according to claim 6, (Relative humidity (RH): 10%, temperature: 20 ° C → 30 ° C → 40 ° C) in a high temperature and high humidity environment (relative humidity (RH): 65%, temperature: 20 ° C → 30 ° C → 40 ° C) , And the temperature difference (? T) of the shape memory polyurethane electrospun web when the heat insulating material is not adhered and when it is adiabated are respectively not less than 4 占 폚 at the maximum.

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