CN118996664A - Preparation method of porous polyurethane fiber - Google Patents

Abstract

The present invention belongs to the field of textile application, and in particular relates to a method for preparing porous (homogeneous porous) polyurethane fibers, that is, a method for constructing porous polyurethane fibers by precipitation-induced phase separation and atmospheric pressure drying. The present invention comprises the following steps: using a polyurethane solution as a polyurethane spinning solution, using an alcohol/water mixed solution as a mixed coagulation bath, allowing the polyurethane spinning solution to enter a spinneret at a set injection speed, and then ejecting it into the mixed coagulation bath for wet spinning to complete phase separation, and the obtained polyurethane gel fiber is dried at atmospheric pressure to obtain a porous (homogeneous porous) polyurethane fiber with high elasticity and high thermal insulation.

Description

Preparation method of porous polyurethane fiber

Technical Field

The invention belongs to the field of textile application, and particularly relates to a preparation method of porous (homogeneous porous) polyurethane fiber, namely a method for constructing porous polyurethane fiber by a precipitation-induced phase separation method and normal-pressure drying.

Background

Polyurethane fibers have been widely used in the fields of clothing, textiles, biomedical materials, and the like, due to their characteristics of high strength, low modulus, high rebound resilience, and high elongation at break.

The prior methods for preparing the porous polyurethane fiber basically adopt a wet spinning method to obtain polyurethane gel fiber; the pore-forming technology in the wet spinning method process is different, some adopt freeze drying method pore-forming, some adopt precipitation induction phase separation method pore-forming; the freeze drying method is to sublimate through an ice crystal template to obtain pores, the energy consumption of the freeze drying method for pore formation is high (75 ℃ below zero), and the period is 3-7 days long; the precipitation-induced phase separation method uses water as a non-solvent (non-solvent of a coagulating bath), the interaction force between the solvent and the non-solvent is large, the dynamic diffusion rate between the solvent and the non-solvent is high, more macropores (50-300 microns) are generated, and the porosity is low.

When the precipitation-induced phase separation method is adopted, because a large number of gas-liquid and liquid-liquid interfaces exist in the polyurethane gel, severe shrinkage and cracking of the gel can be caused in the normal-pressure drying process, and finally the fiber performance is deteriorated (the porosity of the porous fiber product is reduced, the elongation at break is reduced, and the heat insulation performance is not achieved), so that the high-quality porous fiber product cannot be obtained. In order to solve the key technical problem, the following drying process is usually implemented by using a supercritical drying process or freeze drying process, but the methods still have some drawbacks, for example: expensive equipment, rigorous control of process conditions, long period, unfavorable mass production of porous fiber materials and the like, thereby limiting the industrial production of porous polyurethane fibers. Therefore, developing a green, environment-friendly, low-cost and simple porous polyurethane fiber preparation technology and obtaining a porous fiber product with adjustable pore structure and excellent performance is a key problem to be solved in the current stage.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for preparing porous (homogeneous porous) polyurethane fiber by normal-pressure drying, which is environment-friendly, low in cost and simple in process.

In order to solve the above technical problems, the present invention provides a method for preparing a porous (homogeneous porous) polyurethane fiber (i.e., a method for preparing a porous polyurethane fiber constructed by a precipitation-induced phase separation method), comprising the steps of:

s1, preparing polyurethane spinning solution:

Adding polyurethane master batches into an organic solvent, and stirring until the polyurethane master batches are completely dissolved, wherein the obtained polyurethane solution is used as polyurethane spinning solution;

s2, preparing a mixed coagulation bath:

mixing alcohol and water, and stirring uniformly, wherein the obtained alcohol/water mixed solution is used as a mixed coagulation bath (namely, used as a non-solvent of the mixed coagulation bath);

S3, wet spinning:

The polyurethane spinning solution obtained in the step S1 enters a spinneret at a set injection speed, and is then sprayed into the mixed coagulation bath obtained in the step S2 for wet spinning, so that phase separation (separation of a solvent in the polyurethane spinning solution and a non-solvent in the mixed coagulation bath) is completed, and polyurethane gel fibers are obtained; the temperature of the mixed coagulation bath is 30-70 ℃ (preferably 35-65 ℃);

description: the injection speed of the polyurethane spinning solution is controlled by a micro-flow pump, and a spinneret is positioned in a coagulating bath, which is a conventional technology;

s4, drying under normal pressure

And (3) drying the polyurethane gel fiber obtained in the step (S3) under normal pressure to obtain the porous (homogeneous porous) polyurethane fiber.

As an improvement of the preparation method of the invention: the mass fraction of polyurethane master batch in the polyurethane solution is 5-30% (preferably 10-30%).

As a further improvement of the preparation method of the invention:

In step S1, the organic solvent is at least any one of the following: dimethylformamide, dimethylacetamide and dimethyl sulfoxide, namely one or more of dimethylformamide, dimethylacetamide and dimethyl sulfoxide;

In step S2, the alcohol is at least any one of the following: ethanol, isopropanol and tertiary butanol, wherein the mass concentration of the alcohol in the alcohol/water mixed solution is 10% -90% (preferably 30% -60%).

As a further improvement of the preparation method of the invention:

in step S1, the stirring is performed mechanically at 25 to 80 ℃ (preferably 30 to 70 ℃).

As a further improvement of the preparation method of the invention:

In step S3, the wet spinning nozzle has a diameter of 200 to 800 μm (preferably 300 to 700 μm).

As a further improvement of the preparation method of the invention:

in step S3, under the control of the flow rate of the micro-flow pump, the polyurethane spinning solution enters the spinneret at a push speed of 1-10 mL/min (preferably 1.5-5 mL/min), and the collection speed is 20-100 m/min (preferably 10-50 m/min).

As a further improvement of the preparation method of the invention:

In the step S4, the normal pressure drying treatment is to dry at 40-100 ℃ for 1-5 h (preferably at 50-80 ℃ for 2-4.5 h).

As a further improvement of the preparation method of the invention:

the polyurethane is thermoplastic polyurethane.

As a further improvement of the preparation method of the invention:

Polyurethane solution with the mass fraction of 10% is used as polyurethane spinning solution;

the mixed coagulation bath was prepared by using a 60% ethanol/water mixture as a mixed coagulation bath, and the temperature of the mixed coagulation bath was 65 ℃.

In the wet spinning method, a precipitation-induced phase separation method is adopted to prepare holes; namely, the present invention provides a method for preparing a porous polyurethane fiber constructed by an atmospheric drying and precipitation-induced phase separation method. The invention is based on wet spinning technology, regulates and controls the dynamic diffusion coefficient of phase separation by regulating the non-solvent ratio in the coagulating bath, and prepares the porous polyurethane fiber with high elasticity and high thermal insulation performance after drying and shaping under normal pressure. The preparation method is simple and easy to realize, is convenient for industrial production, and the prepared product has good heat insulation performance. The porous structure and high porosity of the polyurethane porous fiber endow the fiber with light weight, and provide potential application for light, thin and high-heat insulation textiles.

The beneficial effects of the invention are as follows:

1. According to the invention, the dynamic diffusion coefficient in the phase separation process is regulated and controlled by selecting a non-solvent (ethanol/water mixed solution) with low interaction force between the solvent and the non-solvent, so that macropore generation is reduced, and the porosity is increased, thereby constructing the porous (homogeneous porous) polyurethane fiber. The method has short period (5-12 hours) and low energy consumption (normal pressure environment drying).

2. According to the invention, the polyurethane porous network structure is reinforced and the capillary stress is resisted by regulating and controlling the coagulation bath temperature.

3. The invention prepares uniform pore structure by changing the non-solvent proportion and the non-solvent temperature in precipitation-induced phase separation.

In summary, the preparation method and the application of the porous polyurethane fiber constructed by the precipitation-induced phase separation method provided by the invention are based on the wet spinning technology, and the porous (homogeneous porous) polyurethane fiber with high elasticity and high thermal insulation performance is prepared by regulating and controlling the dynamic diffusion coefficient in the phase separation process, regulating and controlling the pores in the solidification forming process of the fiber in the wet spinning process and drying under normal pressure. The preparation method is simple and easy to realize, easy to regulate and control, low in cost, environment-friendly and convenient for industrial production.

Drawings

The following describes the embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional electron microscopic view of the porous polyurethane fiber prepared in examples 1-4;

In fig. 1: a to d correspond to examples 1 to 4 in sequence;

FIG. 2 is a stress-strain curve of the porous polyurethane fibers prepared in examples 1 to 4;

FIG. 3 is a graph showing the temperature rise in the heating environment at 35℃for examples 1-4.

Detailed Description

The invention will be further described with reference to the following specific examples, but the scope of the invention is not limited thereto:

The polyurethane master batch is 1180A10 from Basiff (China) Co., ltd, the grain size is 2cm, and the specific gravity of polyurethane is: 1.11g/cm ³, tensile modulus: 12.4MPa, flexural modulus: 17.2MPa. Is thermoplastic polyurethane.

Example 1, a method for preparing porous polyurethane fiber by precipitation-induced phase separation, comprising the following steps in sequence:

(1) And adding 5g of polyurethane master batch into 45g of N, N-dimethylformamide at 30-70 ℃ and stirring until the polyurethane master batch is completely dissolved to obtain polyurethane solution with the polyurethane mass fraction of 10%, and taking the polyurethane solution as polyurethane spinning solution.

(2) 150G of ethanol was added to 350g of water and stirred at 35℃for 1 hour to obtain a 30% ethanol/water mixed solution as a mixed coagulation bath (i.e., as a non-solvent for the mixed coagulation bath);

(3) Wet spinning is adopted:

Under the control of the flow rate of a micro-flow pump, the polyurethane spinning solution enters a spinneret at a push injection speed of 1.5mL/min and is sprayed into the mixed coagulation bath obtained in the step 2) for wet spinning, and phase separation (separation of a solvent in the polyurethane spinning solution and a non-solvent in the mixed coagulation bath) is completed, so that polyurethane gel fibers are obtained;

spinneret diameter 400 microns (i.e., the fiber formed has a diameter of 400 microns); the collection rate is 20m/min; setting the temperature of the mixed coagulation bath to 35 ℃;

(4) And drying the polyurethane gel fiber subjected to phase separation at 50 ℃ and normal pressure for 2 hours to obtain the porous polyurethane fiber.

Example 2a method for preparing a porous polyurethane fiber constructed by precipitation induced phase separation,

The following changes were made with respect to example 1:

(2) 200g of ethanol is added into 300g of water, and the mixture is stirred for 1h at 45 ℃ to obtain 40% ethanol/water mixed solution as a mixed coagulation bath;

in the step (3): setting the temperature of the mixed coagulation bath to 45 ℃;

the remainder was identical to example 1.

Example 3a method for preparing a porous polyurethane fiber constructed by precipitation induced phase separation,

The following changes were made with respect to example 1:

(2) 250g of ethanol is added into 250g of water, and the mixture is stirred for 1h at 55 ℃ to obtain 50% ethanol/water mixed solution as mixed coagulation bath;

In the step (3): setting the temperature of the mixed coagulation bath to 55 ℃;

the remainder was identical to example 1.

Example 4a method for preparing homogeneous porous polyurethane fiber by precipitation induced phase separation,

The following changes were made with respect to example 1:

(2) 300g of ethanol is added into 200g of water, and the mixture is stirred for 1h at 65 ℃ to obtain a 60% ethanol/water mixed solution as a mixed coagulation bath;

In the step (3): setting the temperature of the mixed coagulation bath to 65 ℃;

the remainder was identical to example 1.

The porous polyurethane fibers prepared in experiment 1 and examples 1 to 4 were analyzed in cross section; the electron microscope is shown in fig. 1, and according to fig. 1, it can be known that: example 1 (fig. 1 a) produced a large number of finger-like pores and large cell-like pores, which gradually decreased as the ethanol content in the coagulation bath increased; when the ethanol content was 60% (example 4, fig. 1 d), the inside of the fiber had no macropores and the pore structure was uniform, thus preparing a homogeneous porous polyurethane fiber.

Experiment 2 the porous polyurethane fibers prepared in examples 1 to 4 were tested according to GB/T3923.1-2013, and the stress strain curve is shown in FIG. 2, and according to FIG. 2, it can be seen that: as the macropores within the porous polyurethane fiber decreased, the elongation at break of the fiber increased, and the homogeneous porous fiber of example 4 exhibited a maximum elongation at break of 2865%.

Experiment 3, heating the porous polyurethane fibers prepared in examples 1 to 4 in a heating environment at 35 ℃; the temperature rise curve is shown in fig. 3, and it can be seen from fig. 3 that: the porous polyurethane fibers prepared in examples 1 to 4 had a temperature difference of 3.48,3.59,3.71 and 3.85 c, respectively, and the homogeneous porous polyurethane fiber prepared in example 4 had the highest heat insulation performance.

The performance comparisons of examples 1 to 4 are shown in table 1 below:

TABLE 1 porous polyurethane fiber thermal insulation and stress strain Performance statistics

Example 5-1, the "dimethylformamide" in example 4 was changed to "dimethylacetamide", the amount was kept unchanged, and the rest was the same.

Example 5-2, the "dimethylformamide" in example 4 was changed to "dimethylsulfoxide", the amount was kept unchanged, and the rest was the same.

Example 6-1, the "ethanol" in example 4 was changed to "isopropanol", the amount was kept unchanged, and the rest was the same.

Example 6-2, in which "ethanol" in example 4 was changed to "t-butanol", the amount was kept unchanged, and the rest was the same.

In example 7-1, the polyurethane master batch 5g and the N, N-dimethylformamide 45g in example 4 are changed into the polyurethane master batch 2.5g and the N, N-dimethylformamide 47.5g, namely, a polyurethane solution with the mass fraction of 5% is obtained; the remaining equivalents.

In the example 7-2, the polyurethane master batch 5g and the N, N-dimethylformamide 45g in the example 4 are changed into the polyurethane master batch 15g and the N, N-dimethylformamide 35g, namely the polyurethane solution with the mass fraction of 30 percent is obtained; the remaining equivalents.

Example 8-1, "the urethane solution of example 4 was fed into the spinneret at a bolus rate of 1.5 mL/min" was changed to "the urethane solution was fed into the spinneret at a bolus rate of 2 mL/min"; the remaining equivalents.

Example 8-2, "the urethane solution of example 4 was fed into the spinneret at a bolus rate of 1.5 mL/min" was changed to "the urethane solution was fed into the spinneret at a bolus rate of 3 mL/min"; the remaining equivalents.

Examples 8-3, "the urethane solution of example 4 was fed into the spinneret at a bolus rate of 1.5 mL/min" was changed to "the urethane solution was fed into the spinneret at a bolus rate of 5 mL/min"; the remaining equivalents.

Example 9-1, the "collection rate 20m/min" in example 4 was changed to "collection rate 10m/min"; the remaining equivalents.

Example 9-2, the "collection rate 20m/min" in example 4 was changed to "collection rate 30m/min"; the remaining equivalents.

Examples 9 to 3, the "collection rate 20m/min" in example 4 was changed to "collection rate 50m/min"; the remaining equivalents.

The above examples 5-1 to 9-3 were tested in the experimental manner described above, and the performance comparisons of the respective examples are shown in the following table 1:

TABLE 2 thermal insulation Properties and stress strain Performance statistics of porous polyurethane fibers

Comparative examples 1 to 1, in which the "60% ethanol/water mixture" in example 4 was changed to "90% ethanol/water mixture", were otherwise identical to example 4.

Comparative examples 1 to 2, the remainder was the same as in example 4 except that "60% ethanol/water mixture" in example 4 was changed to "20% ethanol/water mixture".

Comparative example 2-1, the "temperature of the mixed coagulation bath" in example 4 was changed from 65℃to 75℃and the remainder was identical to example 4.

Comparative example 2-2, the "temperature of the mixed coagulation bath" in example 4 was changed from 65℃to 25℃and the remainder was identical to example 4.

All of the above comparative examples were tested in the experimental manner above and compared with the performance of example 4 as shown in table 3 below:

TABLE 3 thermal insulation Properties and stress strain Performance statistics of porous polyurethane fibers

Finally, it should also be noted that the above list is merely a few specific embodiments of the present invention. Obviously, the invention is not limited to the above embodiments, but many variations are possible. All modifications directly derived or suggested to one skilled in the art from the present disclosure should be considered as being within the scope of the present invention.

Claims (9)

1. The preparation method of the porous polyurethane fiber is characterized by comprising the following steps of:

s1, preparing polyurethane spinning solution:

Adding polyurethane master batches into an organic solvent, and stirring until the polyurethane master batches are completely dissolved, wherein the obtained polyurethane solution is used as polyurethane spinning solution;

s2, preparing a mixed coagulation bath:

Mixing alcohol and water, and taking the obtained alcohol/water mixed solution as a mixed coagulation bath;

S3, wet spinning:

the polyurethane spinning solution obtained in the step S1 enters a spinneret at a set injection speed, and is then sprayed into the mixed coagulation bath obtained in the step S2 for wet spinning, so that phase separation is completed, and polyurethane gel fibers are obtained; the temperature of the mixed coagulation bath is 30-70 ℃;

s4, drying under normal pressure

And (3) drying the polyurethane gel fiber obtained in the step (S3) under normal pressure to obtain the porous polyurethane fiber.

2. The method for producing a porous polyurethane fiber according to claim 1, wherein: the mass fraction of polyurethane master batch in the polyurethane solution is 5-30%.

3. The method for producing a porous polyurethane fiber according to claim 2, wherein:

In step S1, the organic solvent is at least any one of the following: dimethylformamide, dimethylacetamide, dimethylsulfoxide;

In step S2, the alcohol is at least any one of the following: ethanol, isopropanol and tertiary butanol, wherein the mass concentration of the alcohol in the alcohol/water mixed solution is 10-90%.

4. A method of preparing a cellular polyurethane fiber according to claim 3, wherein:

In the step S1, the stirring is performed mechanically at 25-80 ℃.

5. The method for producing a porous polyurethane fiber according to claim 4, wherein:

in step S3, the diameter of the wet spinning head is 200-800 μm.

6. The method for producing a porous polyurethane fiber according to claim 5, wherein:

in the step S3, the injection speed is 1-10 ml/min, and the collection speed is 20-100 m/min.

7. The method for producing a porous polyurethane fiber according to any one of claims 1 to 6, characterized in that:

In the step S4, the normal pressure drying treatment is that the drying is carried out for 1 to 5 hours at the temperature of 40 to 100 ℃.

8. The method for producing a porous polyurethane fiber according to any one of claims 1 to 7, wherein:

the polyurethane is thermoplastic polyurethane.

9. The method for producing a porous polyurethane fiber according to any one of claims 1 to 8, characterized in that:

Polyurethane solution with the mass fraction of 10% is used as polyurethane spinning solution;

the mixed coagulation bath was prepared by using a 60% ethanol/water mixture as a mixed coagulation bath, and the temperature of the mixed coagulation bath was 65 ℃.