CN111389319A

CN111389319A - Phase-change thermoregulation microcapsule and preparation method and application thereof

Info

Publication number: CN111389319A
Application number: CN202010345096.0A
Authority: CN
Inventors: 金美菊; 杨福斌; 刘艳春; 刘优娜
Original assignee: NINGBO FIBRE INSPECTION INSTITUTE
Current assignee: NINGBO FIBRE INSPECTION INSTITUTE
Priority date: 2020-04-27
Filing date: 2020-04-27
Publication date: 2020-07-10

Abstract

The invention discloses a phase-change thermoregulation microcapsule and a preparation method and application thereof, belonging to the technical field of materials and comprising a phase-change material core material and a wall material wrapping the phase-change material core material. Researching the influence of experimental parameters on the synthesis of the microcapsule through an orthogonal test, and finally determining a microcapsule synthesis process; the technical indexes of the process are as follows: the average grain diameter of the temperature-adjusting microcapsule is about 1 mu m, and the phase transition temperature is 34-39 ℃. The phase-change temperature-regulating fiber of the invention has the following technical indexes: the average breaking strength of the viscose-based microcapsule phase-change thermoregulation fiber is 18.97cN/tex, and the average breaking elongation is 13.1%.

Description

Phase-change thermoregulation microcapsule and preparation method and application thereof

Technical Field

The invention relates to the technical field of materials, in particular to a phase-change thermoregulation microcapsule and a preparation method and application thereof.

Background

With the improvement of the living standard of people and the development of science and technology, the demand of people on functional fiber is increasing day by day. Research shows that when human body is in heat balance, the average skin temperature is around 33.4 deg.c, the difference between the skin temperature of any part of the body and the average skin temperature is 1.5-3.0 deg.c, and the human body will feel cold or warm over +/-4.5 deg.c.

Phase Change Materials (PCM) are substances that absorb or release heat from or to the environment by virtue of their reversible Phase changes over a range of temperatures. There are about 500 kinds of natural or synthetic phase change materials that have been found and mastered by human beings, and they exist in nature in various forms. The phase-change temperature-regulating fiber capable of freely regulating the temperature within a certain range can be developed by adding the phase-change material into the fiber carrier.

The phase-change thermoregulation fiber is a bidirectional thermoregulation heat-preservation fiber, can absorb, store, redistribute and release heat, has a heat absorption function when the ambient temperature is higher, has a heat release function when the ambient temperature is lower, fundamentally expands the original performance of the fiber, and belongs to novel intelligent fibers.

The development of the phase-change temperature-regulating textile generally adopts a microcapsule coating method, namely phase-change microcapsules are coated on the surface of a fabric through a polymer adhesive, a coating agent and the like, so that the phase-change temperature-regulating textile is obtained. A number of studies have been conducted on such coatings by Triangle, Bryant and Zuckerman et al. The method for preparing the phase-change thermoregulation textile by adopting the microcapsule coating method is simple and convenient, but the physical and mechanical properties and the air permeability of the textile are reduced.

And secondly, a microcapsule spinning method is adopted, namely the phase-change microcapsules are directly implanted into the fibers. Because the microcapsules are permanently sealed in the fibers, the microcapsules have good stability, and the fibers can keep original softness by adopting a common process during subsequent spinning, weaving and dyeing, but the strength of the fibers is greatly lost due to improper control of the synthetic particle size of the microcapsules, a spinning process and the like.

At present, the research on producing phase change thermoregulation fiber by microcapsule composite spinning mainly has the following problems:

(1) because the microcapsule has certain size and property, when the microcapsule and the spinning solution are blended and spun, the spinning performance and the mechanical performance of the composite fiber are easily influenced, and the subsequent spinning processing performance and the application performance are reduced. The size of a common spinneret is about tens of microns, so the size of the microcapsule for spinning is required to be about 1 micron, while the size of the common microcapsule is often 3 microns or more, the microcapsule is easy to block in spinning, the forming is often poor, the phase change performance is poor, and the microcapsule for spinning is difficult to be suitable for synthesizing the microcapsule for spinning.

(2) In the synthesis of the phase-change material microcapsule, higher requirements are put on the coating property of the microcapsule due to repeated phase change. The selection of microcapsule wall materials directly influences the coating function of the microcapsule fibers, and the phase change microcapsules require the wall materials with good film forming property and sealing property to prevent liquid leakage in the using process.

Disclosure of Invention

The invention aims to provide a phase-change thermoregulation microcapsule, a preparation method and application thereof, which are used for solving the problems in the prior art.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a preparation method of a phase-change thermoregulation microcapsule, which comprises the following steps:

adding ethylenediamine into distilled water to obtain an ethylenediamine solution, adding sodium dodecyl sulfate into the ethylenediamine solution, and heating to obtain an ethylenediamine and sodium dodecyl sulfate aqueous solution;

heating paraffin to melt, placing the ethylenediamine and sodium dodecyl sulfate aqueous solution under a high shear condition, rapidly adding the melted paraffin and toluene-2, 4-diisonitrile acid ester, adding an emulsion, emulsifying, and obtaining a stably dispersed emulsion after emulsification;

and carrying out ultrasonic oscillation reaction on the emulsion under the condition of stirring and refluxing, carrying out suction filtration, washing and drying after the reaction is finished, thus obtaining the phase-change thermoregulation microcapsule.

Further, the time of the ultrasonic oscillation is 1-4 h.

Further, the emulsion is hydrolysate of styrene-maleic anhydride copolymer, the concentration of the emulsion is 2.5-20 g/L, and the pH value is 7.4-13.4.

Further, the high shear condition is realized by an emulsifying machine with the rotation speed of 12000 and 28000r/min and the emulsifying time of 0.5-4 h.

Further, the stirring speed under the stirring reflux condition is 400-900r/min, and the temperature is 50-90 ℃.

Further, the paraffin comprises liquid paraffin and solid paraffin, and the mass ratio of the liquid paraffin to the solid paraffin is 1-3: 1.

The invention also provides the phase-change temperature-regulating microcapsule prepared by the preparation method, which comprises a phase-change material core material and a wall material wrapping the phase-change material core material; the phase change material core material is paraffin, and the wall material is toluene-2, 4-diisocyanate and hexamethylene diamine.

Further, the mass ratio of the phase change material core material to the wall material is 1-6: 1-2.

Furthermore, the average particle size of the phase-change temperature-regulating microcapsule is 1 μm, and the phase-change temperature is 34-39 ℃.

The invention also provides an application of the phase-change temperature-regulating microcapsule in phase-change temperature-regulating fibers.

The invention discloses the following technical effects:

the invention takes phase-change material paraffin as core material, toluene-2, 4-diisocyanate (TDI) and hexamethylene diamine as wall material, synthetic copolymer styrene-maleic anhydride hydrolysate (SMH) as emulsifier, and adopts in-situ polymerization technology to coat the phase-change material in the microcapsule to prepare the phase-change temperature-regulating microcapsule, and the influence of experimental parameters on the synthesis of the microcapsule is researched through orthogonal experiments, and finally the microcapsule synthesis process is determined to be that the ultrasonic time is 2h, the mass ratio of the core material to the wall material is 4:1, the concentration of the SMH is 5 g/L, the reaction time is 2h, and the reaction temperature is 70 ℃.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic view showing the influence of mass ratio of core material to wall material on average particle size of a body;

FIG. 2 is a schematic diagram showing the effect of ultrasonic time on volume average particle size;

FIG. 3 is a schematic diagram of the average particle size distribution of microcapsules;

FIG. 4 is a schematic view of the number average particle size distribution of microcapsules;

FIG. 5 is a graph showing the effect of concentration of emulsifier SMH (g/L) on volume average particle size;

FIG. 6 is a graph showing the effect of pH on the volume average particle size of emulsifier SMH;

FIG. 7 is a schematic diagram showing the influence of emulsification rate (r/m) on volume-average particle size;

FIG. 8 is a schematic diagram showing the effect of emulsification time (h) on volume average particle size;

FIG. 9 is a schematic diagram showing the influence of the reaction rotation speed (r/min) on the volume-average particle size;

FIG. 10 is a schematic diagram showing the effect of reaction temperature on volume average particle size;

FIG. 11 is a scanning electron microscope image of phase change thermoregulation microcapsule;

FIG. 12 is a DSC of core material and microcapsules A, B showing the temperature rise process;

FIG. 13 is a DSC chart of the cooling process of the core material and the microcapsule A, B;

FIG. 14 is a TG diagram of core and microcapsules A, B and shell materials;

FIG. 15 is a temperature rise curve for a phase change temperature regulating fiber;

FIG. 16 is a cooling curve of a phase change temperature regulating fiber.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The invention provides a phase-change thermoregulation microcapsule, which comprises a phase-change material core material and a wall material wrapping the phase-change material core material; the phase change material core material is paraffin, and the wall material is toluene-2, 4-diisocyanate and hexamethylene diamine.

As a further improvement of the invention, the paraffin wax comprises liquid paraffin wax and solid paraffin wax, and the mass ratio of the liquid paraffin wax to the solid paraffin wax is 1-3: 1.

As a further improvement of the invention, the mass ratio of the toluene-2, 4-diisocyanate to the hexamethylene diamine is 1-5: 1-2.

Selecting a phase-change temperature-regulating microcapsule core material: mixing liquid paraffin and solid paraffin according to a certain mass ratio, heating and uniformly mixing, cooling and placing. A series of mixed paraffin with different mass ratios are obtained by the method for selection. The melting range, heat absorption enthalpy, solidification range and heat release enthalpy of the mixed paraffin with different mass proportions are measured, and the results are shown in table 1. By integrating the factors such as melting range, peak value, heat absorption enthalpy and the like, when the ratio of the solid paraffin to the liquid paraffin is 3:1, the heat absorption enthalpy and the heat release enthalpy are the largest, so that the ratio of 3: 1.

TABLE 1

As a further improvement of the invention, the mass ratio of the phase change material core material to the wall material is 1-6: 1-2.

The mass ratio of the core material to the wall material has influence on the average particle size of the phase change microcapsule: the mass ratio of the core material to the wall material is 1:2, 1:1, 2:1, 3:1, 4:1, 5:1 and 6:1 respectively, and the results are shown in figure 1. When the mass ratio of the core material to the wall material is gradually increased, the volume average particle size is sharply reduced from about 21 μm to about 5 μm, and when the ratio of the core material is further increased, the volume average particle size is further increased. It can be concluded that this single factor has a significant effect on the volume average particle size. When less paraffin is added, the system has excessive tetraethylenepentamine and isocyanate, and in addition, the isocyanate reacts with water to generate amino, which does not influence the continuous growth of chain segments, so that only a small part of microcapsules are formed, and the majority of the microcapsules are polyurea particles, so the volume is larger; when the proportion of the paraffin gradually rises, a large amount of microcapsules begin to be generated, so that the average particle size of the microcapsules is reduced; when the amount of wax added is increased to an excessive amount, the amount of wall material is insufficient to form a coating on each small dispersed wax particle, and thus agglomeration of the wax occurs and the volume average particle diameter increases. The optimal core-shell ratio is 4:1 in comprehensive consideration.

As a further improvement of the invention, the average particle size of the phase-change temperature-adjusting microcapsule is 1 μm, and the phase-change temperature is 34-39 ℃.

The invention also provides a preparation method of the phase-change temperature-regulating microcapsule, which comprises the following steps:

heating paraffin to melt slightly, putting the ethylenediamine and sodium dodecyl sulfate aqueous solution under a high shear condition, quickly adding the melted paraffin and toluene-2, 4-diisonitrile acid ester, adding an emulsion, emulsifying, and obtaining a stably dispersed emulsion after emulsification;

As a further improvement of the invention, the time of the ultrasonic oscillation is 1-4 h.

Influence of ultrasonic time on average particle size of phase change microcapsules: the ultrasonic oscillation is helpful to disperse large particle groups in the reaction liquid into small particles and gather ultrafine particles into slightly larger particle groups, so that the particle size distribution of the microcapsule is narrowed, and the volume average particle size is greatly reduced. As can be seen from FIG. 2, the volume average particle diameter was significantly reduced as the ultrasonic time was increased, and remained substantially unchanged after more than 2 hours. Therefore, the ultrasonic oscillation time is selected to be 2 h.

Volume average particle diameter (d)_v) Is thatCalculated as the volume fraction of the total mass of microcapsules of different particle size, and the number average particle diameter (d)_n) The method is calculated according to the number fraction of the microcapsules with different particle sizes in the total, and the calculation methods of the microcapsules and the total are different. That is, the volume average particle size is determined by the volume of the larger portion; the number average particle diameter is determined by the number of the particles. Distribution index PDI ═ d_v/d_nThe closer the PDI value is to 1, the better the dispersibility of the microcapsules. Experimental results can prove that the ultrasonic oscillation is helpful for dispersing large particle groups in the reaction liquid into small particles one by one, and gathering ultrafine particles into slightly larger particle groups, so that the particle size distribution of the microcapsule is narrowed, and the volume average particle size is greatly reduced. The microcapsules prepared by the laser particle size analyzer test had a volume average particle size and a number average particle size of 4.08 μm and 1.04 μm, respectively, and PDI was 4.08/1.04 and 3.93, as shown in fig. 3 and 4.

As a further improvement of the invention, the emulsion is hydrolysate of styrene-maleic anhydride copolymer, the concentration of the emulsion is 2.5-20 g/L, and the pH value is 7.4-13.4.

Influence of emulsifier concentration on phase change microcapsule particle size, emulsifier SMH (styrene-maleic anhydride polymer) concentrations are selected to be 2.5 g/L, 5 g/L, 10 g/L, 15 g/L and 20 g/L respectively to carry out a single-factor experiment, as shown in figure 5, when the SMH concentration is gradually increased from 2.5 g/L to 20 g/L, the volume average particle size is gradually increased after being reduced because the good dispersion and emulsification effect is not achieved when the SMH dosage is small, the paraffin is not uniformly dispersed, so the volume average particle size is large, when the SMH dosage is gradually increased, the dispersion and emulsification effect is gradually enhanced, the volume average particle size is obviously reduced, when the dosage is gradually increased, redundant SMH is coated in the microcapsule, so the particle size is increased, and when the SMH dosage is 5 g/L, the volume average particle size reaches the minimum value, which is the optimal value of the SMH dosage.

Influence of the pH value of the aqueous solution of the emulsifier SMH on the average particle size of the phase-change microcapsule: the SMH aqueous solution with pH of 7.4, 8.4, 9.4, 10.4, 11.4, 12.4 and 13.4 is selected respectively for single-factor experiment. As shown in fig. 6: as the pH of the SMH aqueous solution increased from 7.4 to 13.4, the microcapsules had a volume average particle size difference of within 1.5 μm, so it can be concluded that the pH of the SMH aqueous solution had a small effect on the volume average particle size.

As a further improvement of the invention, the high shear condition is realized by an emulsifying machine with the rotation speed of 12000 and 28000r/min and the emulsifying time of 0.5-4 h.

Influence of emulsification speed on average particle size of microcapsules: 5 different emulsifying machine rotating speeds are selected for experiments, wherein the rotating speeds are 12000r/min, 16000r/min, 20000r/min, 24000r/min and 28000r/min respectively, and the results are shown in figure 7. The average particle size of the microcapsules is reduced from 8.2 μm to 5.3 μm as the emulsification rate is increased from 12000r/m to 28000r/m, and the average particle size is gradually reduced to 5.5 μm after the emulsification rate is increased to 20000r/m or more. From this it can be concluded that: the emulsifying rotation speed is an important factor influencing the volume average particle size of the microcapsule, the volume average particle size of the microcapsule can be obviously reduced by increasing the emulsifying rotation speed, but the improving effect is weakened when a certain rotation speed is reached. Comprehensively considering the experimental conditions and the experimental results, the emulsifying rotation speed is determined to be 20000 r/min.

Influence of emulsification time on average particle size of microcapsules: the emulsification times of 0.5h, 1.0h, 2.0h, 3.0h and 4.0h were selected respectively for experiments, as shown in FIG. 8. The volume average particle size decreased significantly with increasing emulsification time, and increased slightly over 2 hours, probably due to the increased thickness of the polymer film coating on the paraffin wax surface. If the emulsification is carried out for less than 2 hours, the reaction is not sufficiently carried out. The optimum emulsification time was determined to be 2 hours.

As a further improvement of the invention, the stirring speed of the stirring reflux condition is 400-900r/min, and the temperature is 50-90 ℃.

Influence of reaction speed on average particle size of microcapsules: the reaction rotation speeds of 400r/min, 500r/min, 600r/min, 700r/min, 800r/min and 900r/min were respectively selected for experiments, as shown in FIG. 9. When the reaction speed is increased from 400r/min to 900r/min, the difference of the volume-average particle size is within 2 μm, and the following results are shown: the reaction speed has little influence on the average grain diameter of the microcapsule body. The reaction speed is only required to be 700r/min, and the reaction liquid is easy to splash when the speed is too high.

The reaction temperature influences the average particle size of the microcapsule: the reaction temperatures of 50 ℃, 60 ℃, 70 ℃, 80 ℃ and 90 ℃ are respectively selected for experiments, as shown in fig. 10, when the temperature is increased from 50 ℃ to 90 ℃, the volume average particle size is obviously reduced, probably because the diffusion speed of the monomer is accelerated along with the increase of the reaction temperature, and the monomer is rapidly adsorbed on the surface of paraffin to form a film. On the other hand, since the core material is paraffin with a relatively high viscosity, the viscosity thereof decreases with an increase in temperature, which facilitates dispersion of the paraffin, thereby obtaining microcapsules with a small particle size. It can be concluded from this that the reaction temperature is one of the main factors influencing the average particle size of the microcapsules. The optimum reaction temperature was determined to be 70 ℃.

And selecting whether ultrasonic waves exist in the phase-change temperature-regulating microcapsule preparation process, the mass ratio of the core material to the wall material, the concentration of SMH, the reaction time and the reaction temperature as influence factors to perform orthogonal experiments according to the conditions, and searching the influence of each factor on the volume average particle diameter in the phase-change microcapsule preparation process. The pH value of the aqueous solution of the SMH is fixed at 12, the emulsifying rotating speed is fixed at 20000r/min, and the rotating speed is fixed at 700r/min during the reaction. The experimental conditions are shown in Table 2.

As can be seen from table 2, the very difference in the term "presence or absence of ultrasonic waves" reached 25.375, indicating that it had the greatest effect on the volume average particle size of the phase-change microcapsules; the "ratio of core material to wall material" is extremely poor at 12.175, which indicates that it also has a significant influence on the volume average particle size of the phase-change microcapsules; the extreme differences of the reaction time, the reaction temperature and the concentration of SMH are 5.775, 5.475 and 2.700 respectively, and compared with the two factors, the three factors have smaller influence on the volume average particle size of the phase-change microcapsule.

From the 4 mean values, the optimal process conditions can be determined, wherein the ultrasonic time is 2h, the mass ratio of the core material to the wall material is 4:1, the concentration of SMH is 5 g/L, the reaction time is 2h, and the reaction temperature is 70 ℃.

TABLE 2

Example 1

The preparation method of the phase-change temperature-regulating microcapsule comprises the following steps:

The mass ratio of the core material to the wall material is 4: 1.

The time of the ultrasonic oscillation is 2 hours.

The mass ratio of the toluene-2, 4-diisocyanate to the hexamethylene diamine is 3: 1.5.

the emulsion is hydrolysate of styrene-maleic anhydride copolymer, the concentration of the emulsion is 5 g/L, and the pH value is 12.

The high shear condition is realized by an emulsifying machine, the rotating speed is 20000r/min, and the emulsifying time is 2 h.

The stirring speed under the stirring reflux condition is 700r/min, and the temperature is 70 ℃.

Test examples the phase-change thermoregulation microcapsule prepared in example 1 was tested for properties

1. Analysis by scanning electron microscope

The apparent morphology of the phase-change microcapsules was observed by JSM-5600L V scanning electron microscope and the results are shown in FIG. 11.

As can be seen from fig. 11, the microcapsules have a small particle size and a narrow particle size distribution, approximately in the range of 1-5 μm. The microcapsule has good integral dispersion degree, and the particles are basically not adhered to each other. The surface of the microcapsule is not broken basically, probably because the wall material has sufficient reaction at the interface and can completely coat the emulsified phase-change material microspheres.

2. Heat absorption and release performance of temperature-regulating microcapsule

A differential scanning calorimeter (DSC method) was used to measure the melting range, the endothermic enthalpy, the solidification range, and the exothermic enthalpy of the core material (paraffin wax mixed with liquid paraffin wax at a mass ratio of 3: 1) and the microcapsules, specifically, see table 3, where the microcapsule a was the microcapsule prepared in example 1, and the microcapsule B was prepared without ultrasonic oscillation.

TABLE 3

The DSC shows that most of the enthalpy is concentrated between 30 ℃ and 37 ℃ as shown in figures 12 and 13 in the process of temperature rise and temperature fall, and is suitable for regulating the temperature of the human body.

3. Heat resistance of temperature-regulating microcapsule

Thermogravimetric analysis was performed on the core material, the microcapsule a, the microcapsule B and the shell material (polyurea) using a thermogravimetric analyzer, respectively, and the cracking temperatures are listed in table 4, and the cracking process is shown in fig. 14.

TABLE 4

Table 4 shows that the cracking temperatures of the core material, the microcapsule A, B and the shell material are 130 ℃, 200 ℃ and 260 ℃ respectively, which indicates that the shell material has a protective effect on the phase-change material paraffin between 130 ℃ and 200 ℃; meanwhile, the phase-change material paraffin is better coated in the shell material and has better heat resistance.

4. Acid resistance of temperature-regulating microcapsules

Weighing 1g of temperature-adjusting microcapsule, adding 250ml of water for dissolving, putting into a flat-bottomed flask, adding 2g of sulfuric acid, heating and observing, wherein the result is shown in table 5, and the microcapsule is known to be relatively acid-resistant according to the observation result. The acid resistance of the microcapsules does not cause great problems in the acid bath process and the acid washing process of post-treatment in the viscose spinning process.

TABLE 5

Operating procedure	Phenomenon of liquid test
		Adding acid for 1min	Microcapsule particle suspension, water transparency
40℃，30min	Microcapsule particle suspension, water transparency
		60℃，30min	Microcapsule particle suspension, water transparency
80℃，30min	A small amount of paraffin is separated out, microcapsule particles are suspended, and water is transparent
		100℃，30min	A small amount of paraffin is separated out, floccules appear and water is semitransparent

5. Alkali resistance of temperature-regulating microcapsule

Weighing 1g of temperature-adjusting microcapsule, adding 250ml of water for dissolving, putting into a flat-bottomed flask, adding 2.5g of sodium hydroxide, heating and observing, wherein the result is shown in table 6, and the microcapsule is known to be more alkali-resistant according to the observation result. The alkali resistance of the microcapsules does not cause much problem in the desulfurization process.

TABLE 6

Operating procedure	Phenomenon of liquid test
		Adding alkali for 1min	Microcapsule particle suspension, water transparency
40℃，30min	Microcapsule particle suspension, water transparency
		60℃，30min	Microcapsule particle suspension, water transparency
80℃，30min	Very little paraffin is separated out, microcapsule particles are suspended, and water is transparent
		100℃，30min	A small amount of paraffin is separated out, floccules appear, and water is slightly transparent

The invention adopts a solution composite spinning method, adds phase-change microcapsules into spinning solution, and performs blended spinning to prepare the phase-change thermoregulation viscose fiber. Selecting high-quality cellulose pulp such as cotton pulp, wood pulp and the like as raw materials, and carrying out the steps of dipping, squeezing, crushing, ageing, yellowing, dissolving, mixing, filtering, ripening, defoaming, spinning, drafting, refining, drying and the like, wherein the preparation process is consistent with that of common viscose fiber, and specifically comprises the following steps:

(1) cellulose yellow grease is prepared by soaking, squeezing, crushing, ageing and yellowing cellulose pulp, wherein the process parameters comprise 20% of alkali mass fraction, 40 ℃ of soaking temperature, 30min of soaking time, 1: 40 of bath ratio, 2.8 of pressing multiple, 150 g/L of crushing degree, 25 ℃ of low-temperature ageing temperature, 72h of low-temperature ageing temperature, 2h of yellowing time, 25 ℃ of temperature and 125% of carbon disulfide.

(2) Adding temperature-regulating microcapsules into cellulose xanthate, mixing and stirring, filtering and curing to obtain spinning glue with the temperature-regulating microcapsules having effective cellulose content of about 10% and alkali content of about 7.5%;

(3) and spraying the prepared spinning glue into a coagulating bath with the temperature of 48 ℃, the coagulating bath containing 20 g/L of sulfuric acid, 15 g/L of zinc sulfate and 330 g/L of sodium sulfate for forming, and performing post-treatment such as drafting, refining, drying and the like to obtain the temperature-regulating microcapsule fiber.

Phase change thermoregulation microcapsule fiber performance test

a. Temperature regulation Performance test

Testing when the outside environment temperature rises: the temperature-controlled microcapsule fiber and the common viscose fiber are placed in a constant-temperature constant-humidity environment (the temperature is 20 ℃ and the humidity is 60%) and balanced for 24 hours, then the temperature-controlled microcapsule fiber and the common viscose fiber are respectively placed on a heat-insulation board at 40 ℃, the surface temperature of the fiber is measured by an infrared thermometer every 2-3 seconds, and a temperature-rise curve is recorded and drawn, as shown in figure 15.

Testing when the outside environment temperature is reduced: placing the temperature-controlled microcapsule fiber and common viscose fiber in a 42 ℃ oven, heating and preserving heat for 2h, then quickly taking out, naturally cooling to the ambient temperature (temperature 20 ℃ and humidity 60%), measuring the surface temperature of the fiber by using an infrared thermometer at intervals of 2-3s in the process, recording and drawing a temperature-reducing curve, and referring to fig. 16.

As can be seen from fig. 15: at 30 ℃, the microcapsule temperature-regulating fiber begins to absorb heat, the self temperature-rising rate is gradually slowed down, the temperature reaches the minimum value at 35 ℃, and finally the temperature slowly reaches 37 ℃; as can be seen from fig. 16: at 34 ℃, the microcapsule temperature-regulating fiber begins to release self heat, the self cooling rate is reduced, the temperature reaches the minimum value at 30 ℃ and finally reaches 20 ℃. The temperature of the common viscose fiber is higher than that of the temperature-adjusting fiber in both temperature rising speed and temperature lowering speed.

Experiments show that: the temperature control range of the viscose-based microcapsule phase change temperature-adjusting fiber is about 20-37 ℃, and is basically consistent with the heat absorption and heat release temperature range of the adopted phase change microcapsule.

b. Selection of temperature regulation performance characteristic index

The temperature regulating and preserving effects of the phase change temperature regulating fibers are detected and researched by adopting differential scanning calorimetry and differential thermal analysis methods respectively, and the results are shown in tables 7 and 8.

TABLE 7

TABLE 8

The above two tables were analyzed to show that: for the microcapsule and the phase-change temperature-adjusting fiber, the test results of the two methods are basically consistent, but the phase-change point can be found more accurately by a Differential Thermal Analysis (DTA) curve. Therefore, a relatively intuitive Differential Thermal Analysis (DTA) measurement result, namely the phase transition temperature, is finally selected as a characteristic index of the phase-change thermoregulation fiber.

c. Strength test of temperature-regulating microcapsule fiber

For phase change thermoregulation viscose fiber test samples with different microcapsule effective contents, fiber breaking strength and breaking elongation are tested according to the national standard GB/T14344-2008 'chemical fiber filament tensile property test method'. See table 9:

TABLE 9

From the test results, when the adding amount of the microcapsule is less than 12%, the breaking strength of the fiber is more than 18.97cN/tex, and the breaking elongation is more than 13%. For ordinary viscose fibers, the product standard GB/T13758-2008 viscose filament stipulates: the first-class product has dry breaking strength not less than 1.75cN/dtex and dry elongation at break (16.0-25.0)%. Therefore, the elongation at break of the phase change thermoregulation fiber added with the microcapsule is reduced.

d. Influence of particle size of temperature-regulating microcapsules

The microcapsule has the particle size of more than 3 mu m, is difficult to spin and poor in forming, and is not suitable for subsequent processing.

The phase-change microcapsules with the grain diameters of 2 microns and 1 micron are respectively adopted, the addition amount is 12 percent, the viscose-based microcapsule phase-change temperature-regulating fiber is spun in a trial mode, and the test results of the physical properties are shown in a table 10. As can be seen from the table: the microcapsule grain size is increased, the elongation at break of the phase change fiber is reduced, and the variation coefficient of the breaking strength is obviously increased. The spinnability is obviously reduced.

TABLE 10 comparison of viscose-based microcapsule phase-change thermoregulation fibers prepared from microcapsules of different particle sizes

In addition, two types of dyes commonly used for cellulose materials, namely direct dyes and reactive dyes, are selected to dye the microcapsule phase change thermoregulation viscose fiber and the common viscose fiber respectively, and a spectrophotometer is utilized to determine the dye-uptake degree and the final dye-uptake rate in the dyeing process; and evaluating the fixation degree according to indexes such as soaping color fastness, rubbing color fastness and the like of the dyed sample. Therefore, the influence of the dye concentration and the dye bath temperature on the dyeing performance of the phase change thermoregulation viscose fiber and the common viscose fiber of the microcapsule is respectively researched. The experimental results show that: the dyeing performance of the microcapsule phase-change thermoregulation viscose fiber is basically consistent with that of the common viscose fiber. For analytical reasons, it is possible that the phase change material for textile use generally does not function substantially for dyeing processes with a 40 ℃ dye-out, since the temperature control range is usually below 40 ℃. In addition, the microcapsule phase change material is added into the fiber spinning solution in a physical form, and the molecular structure is not changed, so that the dyeing performance is basically not influenced.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. The preparation method of the phase-change thermoregulation microcapsule is characterized by comprising the following steps:

2. The preparation method of the phase-change temperature-regulating microcapsule according to claim 1, wherein the time of the ultrasonic oscillation is 1-4 h.

3. The method for preparing phase-change thermoregulation microcapsule according to claim 1, wherein the emulsion is hydrolysate of styrene-maleic anhydride copolymer, the concentration of the emulsion is 2.5-20 g/L, and the pH is 7.4-13.4.

4. The method for preparing phase-change thermoregulation microcapsule according to claim 1, wherein the high shear condition is realized by an emulsifying machine, the rotation speed is 12000 and 28000r/min, and the emulsifying time is 0.5-4 h.

5. The preparation method of the phase-change temperature-regulating microcapsule as claimed in claim 1, wherein the stirring speed under the stirring reflux condition is 400-900r/min and the temperature is 50-90 ℃.

6. The phase-change thermoregulation microcapsule according to claim 1, wherein the paraffin comprises liquid paraffin and solid paraffin, and the mass ratio of the liquid paraffin to the solid paraffin is 1-3: 1.

7. The phase-change thermoregulation microcapsule prepared by the preparation method of the phase-change thermoregulation microcapsule according to any one of claims 1 to 6, which is characterized by comprising a phase-change material core material and a wall material wrapping the phase-change material core material; the phase change material core material is paraffin, and the wall material is toluene-2, 4-diisocyanate and hexamethylene diamine.

8. The phase-change thermoregulation microcapsule according to claim 7, wherein the mass ratio of the phase-change material core material to the wall material is 1-6: 1-2.

9. The phase-change thermoregulation microcapsule according to claim 7, wherein the phase-change thermoregulation microcapsule has an average particle size of 1 μm and a phase-change temperature of 34-39 ℃.

10. Use of a phase change tempering microcapsule according to any of claims 7-9 in a phase change tempering fiber.