CN110129915B

CN110129915B - Method for preparing black polylactic acid fiber by coloring stock solution

Info

Publication number: CN110129915B
Application number: CN201910449813.1A
Authority: CN
Inventors: 付少海; 张丽平; 董浩; 李敏; 王冬; 刘明明
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2019-05-28
Filing date: 2019-05-28
Publication date: 2020-11-06
Anticipated expiration: 2039-05-28
Also published as: CN110129915A

Abstract

The invention discloses a method for preparing black polylactic acid fiber by coloring stock solution, belonging to the technical field of fiber production. The method comprises the steps of adding modified carbon black and polylactic acid into a pulverizer to be pulverized and mixed, adding the pulverized and mixed materials into a double-cone micro mixing mill after the pulverized and mixed materials are fully mixed, heating the mixture to a specified temperature, extruding and drafting the mixture to a winder after the molten and mixed materials are melted and blended to prepare the polylactic acid fiber. The invention can effectively control the mechanical property, color depth, fiber diameter and other properties of the colored polylactic acid fiber by adjusting the conditions of the type of the carbon black, the ratio of the carbon black to the polylactic acid, the winding speed, the drafting process and the like. The obtained polylactic acid fiber has high color fastness, easy control of color depth, small fiber difference among different batches in the same process, and suitability for continuous production.

Description

Method for preparing black polylactic acid fiber by coloring stock solution

Technical Field

The invention particularly relates to a method for preparing black polylactic acid fiber by coloring stock solution, belonging to the technical field of fiber production.

Background

Polylactic acid is a high molecular material which is derived from natural raw materials such as corn, soybean and the like and has good biocompatibility, and is often applied to the medical field such as surgical sutures, orthopedic fixation equipment, drug controlled release and the like. In recent years, due to breakthrough of synthesis methods, the molecular weight and molecular weight distribution of polylactic acid are well controlled, so that the polylactic acid becomes an important raw material of biomass fibers. In addition, the polylactic acid fiber has mechanical properties comparable to those of polyester fiber, has the advantages of easy biodegradation, wrinkle resistance, ultraviolet resistance, higher limited oxygen index, good hydrophilicity and the like, and is one of the biomass fibers which are most important and have good application prospects in the textile field.

Polylactic acid fiber is similar to polyester fiber in chemical structure, and is usually dyed with disperse dye. But because the linear aliphatic thermoplastic polyester structure of the polylactic acid fiber has poor hydrolysis resistance, the mechanical property of the dyed polylactic acid fiber is reduced by adopting the traditional disperse dye dyeing process, and the wearability of the polylactic acid is influenced. For example, the author Yang named as company of dispersion dye exhaustion, color yield, and color fastness between polylactic acid and poly (ethylene terephthalate) (2010,90(12):3285-3290) in Journal of applied Polymer Science dyes adopts disperse dyes to dye PLA, and research results show that increasing the pH value of a dye bath is beneficial to the dye uptake of the disperse dyes on the PLA fiber, but when the pH value is higher than 7, the PLA fiber is strongly hydrolyzed, and the mechanical properties of the PLA fiber are seriously influenced.

The dope dyeing technique is a dyeing method that a coloring agent is added into a spinning solution or a melt to obtain a colored polymer or a melt, and the colored polymer or the melt is directly made into colored fibers through spinning. Pigment used in stock solution coloring exists in a medium in a dispersion state, so the particle size and distribution characteristics of the pigment directly influence the color performance and mechanical property of colored fiber, and the traditional black fiber is black polyester fiber obtained by coloring the stock solution of the polyester fiber by using carbon black; U.S. Pat. No. 3, 07, 099,534 discloses a process for preparing a black liquid colorant for dope-colored polyester fibers by adding carbon black, which is liquid-phase oxidized and neutralized by gas-phase oxidation, to a polyester solution to obtain a jet-black polyester having a bluish hue. However, the black fiber material obtained by the above method has weak mechanical properties and color fastness, and a method for preparing colored polylactic acid fiber with strong mechanical properties and more excellent color fastness needs to be found.

Disclosure of Invention

In order to solve the problems, the invention is based on stock solution coloring, utilizes the blending of modified carbon black and polylactic acid, and combines the conditions of specific ratio of the carbon black to the polylactic acid, winding speed, drafting process and the like to control the particle size of the carbon black and improve the compatibility of carbon black pigment and polylactic acid matrix so as to prepare the stock solution coloring black polylactic acid fiber with excellent thermodynamic property.

The first purpose of the invention is to provide a preparation method of black polylactic acid fiber, which utilizes non-ionic modified carbon black and polylactic acid to melt and extrude, and then drafts to obtain black polylactic acid fiber; the mass part of the nonionic modified carbon black relative to the polylactic acid is 1-2.5%.

In one embodiment of the present invention, the nonionic modified carbon black is a carbon black having polyester structural units grafted on the surface.

In one embodiment of the invention, the polyester building blocks comprise one or more of polylactic acid, polyethylene terephthalate, polypropylene terephthalate, polybutylene succinate.

In one embodiment of the present invention, the melt extrusion temperature is 170 to 210 ℃.

In one embodiment of the invention, the melt extrusion is carried out in a double-cone micro-compounder; wherein the temperatures of a left plate and a right plate in the double-cone micro mixing mill are the same, and the rotating speed of a screw is 50-80 rpm.

In one embodiment of the invention, the method further comprises winding with a winder followed by drawing after extrusion.

In one embodiment of the invention, the winding speed of the winder is 5 to 30 m/min.

In one embodiment of the invention, the drawing is performed in a water bath at 65 to 95 ℃.

In one embodiment of the present invention, the time for the drawing is 20 to 120 seconds.

In one embodiment of the present invention, the draft ratio is 1.5 to 3 times.

In one embodiment of the invention, the carbon black comprises one or more of MA-100 type carbon black, rubber carbon black N110, N220, N330, N550, pigment carbon black R330, R400, R660.

Drying polylactic acid in a vacuum oven at 80 ℃ for 24 hours, taking a certain amount of polylactic acid and carbon black, fully crushing and mixing the polylactic acid and the carbon black in a powder grinding machine, then adding the polylactic acid and the carbon black into a double-cone micro mixing mill, heating to a specified temperature, and stretching the polylactic acid to a small winder after the polylactic acid is melted and extruded to prepare black polylactic acid fiber; the fiber wound on the winding machine is taken down and placed in a water bath for drafting, and the fiber is endowed with more excellent mechanical property by controlling factors such as the temperature of the water bath, the residence time in the water bath, the drafting multiplying power and the like.

The second purpose of the invention is to provide a black polylactic acid fiber, which is prepared by the method.

A third object of the present invention is to provide a textile product comprising the black polylactic acid fiber.

The fourth object of the present invention is to apply the black polylactic acid fiber described above to the field of clothing.

The invention has the following beneficial effects:

according to the invention, by a physical blending method, firstly, carbon black and polylactic acid are uniformly mixed, added into a double-cone micro mixing mill according to a certain proportion for melt blending, and then extruded and drawn to a small-sized winding machine to prepare the stock solution coloring black polylactic acid fiber. Obtaining the fibers with different mechanical properties through different drafting processes. The method has the following characteristics:

1. the coloring process of the fiber in the method of the invention is to add a colorant into the melt to obtain the colored fiber, belonging to the physical change process. The coloring agent in the fiber prepared by spinning and drafting is directly fixed in the fiber, and the post-fiber dyeing link is omitted, so that the damage of improper dyeing condition on the mechanical property of the fiber is avoided, the energy consumption is reduced, the production cost of the colored yarn is reduced, the pollution problem caused by dyeing can be avoided, and the method is a green dyeing method.

2. In the method, the mechanical properties, the color depth, the fiber diameter and other properties of the colored polylactic acid fiber can be controlled by adjusting the type and the performance of the carbon black, the ratio of the carbon black to the polylactic acid, the winding speed, the drafting process and other conditions, wherein the strength can reach more than 0.22N/tex, and the mechanical properties of the fiber can not be lost; the coloring depth is high, the CMC DE is not more than 0.5, and the dyeing effect is very uniform. The obtained polylactic acid fiber has high color fastness, easy control of color depth, small fiber difference among different batches in the same process, and suitability for continuous production.

Detailed Description

In order to clearly understand the technical contents of the present invention, the following examples are given in detail for the purpose of better understanding the contents of the present invention and are not intended to limit the scope of the present invention.

And (3) measuring the mechanical property: testing the mechanical property of the fiber by adopting an EZ-SX type electronic universal testing machine;

and (3) color property determination: testing the color performance of the fiber by adopting a CI7800 type computer color testing and matching instrument; wherein the level of CMC DE is evaluated: the color change can not be observed within 1, and the dyeing is uniform.

And (3) soaping color fastness determination: testing the soaping color fastness of the product by GB/T3921A-2008;

the preparation method of the nonionic modified carbon black comprises the following steps: 2.5g of silane coupling agent and 5g of carbon black are added into an alcohol-water mass ratio of 9: 1 in 100g of mixed solvent, performing ultrasonic treatment for 30min, transferring to a water bath kettle at 40 ℃, preserving heat, stirring and reacting for 24 h. And then adding 1g of the mixture into 50g of toluene solution, adding 1g of nonionic comonomer, heating, adding 0.06g of catalyst stannous octoate, and carrying out heat preservation reaction for a period of time to obtain the nonionic modified carbon black. Wherein the non-ionic comonomer comprises one or more of lactide, ethylene terephthalate, trimethylene terephthalate, butylene terephthalate and butylene succinate.

Example 1

Putting polylactic acid in a vacuum oven at 80 ℃ for drying for 24 hours, taking 10g of dried polylactic acid and 0.15g of nonionic modified carbon black with a polylactic acid structure grafted on the surface, fully stirring and mixing the polylactic acid and the nonionic modified carbon black, adding the mixture into a double-cone micro mixing mill, adjusting the rotating speed of a screw to 60rpm, raising the temperature of a left plate and a right plate to 190 ℃, stretching the polylactic acid to a small winder after the polylactic acid is melted and extruded, adjusting the winding speed to 20m/min, taking down the fiber wound on the winder after a period of time, placing the fiber in a water bath kettle at 70 ℃ for stretching for 30 seconds, improving the orientation degree of the fiber and extending the length of the fiber to 2 times of the original fiber. Taking out and drying at room temperature.

Surface grafting polylactic acid structure nonionic modified carbon black: 2.5g of silane coupling agent and 5g of carbon black are added into an alcohol-water mass ratio of 9: 1 in 100g of mixed solvent, performing ultrasonic treatment for 30min, transferring to a water bath kettle at 40 ℃, preserving heat, stirring and reacting for 24 h. And then adding 1g of the mixture into 50g of toluene solution, adding 1g of lactide, heating, adding 0.06g of catalyst stannous octoate, and carrying out heat preservation reaction for a period of time to obtain the nonionic modified carbon black.

Example 2 Effect of amount of modified carbon Black on fiber products

Referring to example 1, the amount of the nonionic modified carbon black was changed to 0.1g, 0.2g, 0.25g, 0.3g, 1g, and 2g, respectively, and the other conditions were not changed, to prepare corresponding fiber products. The specific performance results of the product are shown in table 1.

TABLE 1 Performance results for fibers obtained with varying amounts of non-ionic modified carbon Black

Amount of modified carbon black	Strength (N/tex)	Fastness to soaping	K/S	CMC DE
					0.1g	0.22	5	19.63	0.45
0.15g	0.37	5	20.23	0.23
					0.2g	0.29	5	21.38	0.31
0.25g	0.23	5	22.10	0.29
					0.3g	0.15	5	23.09	0.28
1g	0.12	5	23.55	0.25
					2g	0.10	5	23.58	0.26

Example 3

Referring to example 1, the drafting time was changed to 10s, 20s, 60s, and 300s, respectively, and the other conditions were not changed, to prepare corresponding fiber products. The specific results are shown in Table 2.

TABLE 2 Performance results for fibers obtained at different draw times

Drafting time(s)	Strength (N/tex)	Fastness to soaping	K/S	CMC DE
					10	0.27	5	20.23	0.25
20	0.30	5	20.22	0.23
					60	0.35	5	20.00	0.23
300	0.33	5	20.12	0.21

Example 4

Referring to example 1, the corresponding fiber products were prepared by replacing the water bath temperature with 65 ℃, 70 ℃, 80 ℃, 85 ℃,90 ℃ and 95 ℃ respectively, and keeping the other conditions unchanged. The specific results are shown in Table 3.

TABLE 3 Performance results for fibers obtained at different bath temperatures

Temperature of Water bath (. degree.C.)	Strength (N/tex)	Fastness to soaping	K/S	CMC DE
					65	0.27	5	20.30	0.23
70	0.33	5	20.22	0.23
					80	0.36	5	20.15	0.25
85	0.34	5	20.19	0.24
					90	0.29	5	20.32	0.22
95	0.26	5	20.34	0.23

Example 5

Referring to example 1, corresponding fiber products were prepared by replacing the winding speeds with 5m/min, 20m/min, and 30m/min, respectively, and leaving the other conditions unchanged. The specific results are shown in Table 4.

TABLE 4 Performance results for fibers obtained at different winding speeds

Comparative example 1

Putting polylactic acid in a vacuum oven at 80 ℃ for drying for 24 hours, taking 10g of dried polylactic acid and 2g of original carbon black, fully stirring and mixing the polylactic acid and the original carbon black in a flask, adding the mixture into a double-cone micro mixing mill, adjusting the rotation speed of a screw to 60rpm, raising the temperature of a left plate and a right plate to 190 ℃, drawing the polylactic acid to a small winder after the polylactic acid is melted and extruded, adjusting the winding speed to 10m/min, taking down the fiber wound on the winder after a period of time, putting the fiber in a water bath kettle at 70 ℃ for drawing for 30 seconds, improving the orientation degree of the fiber and extending the length of the fiber to 2 times of the original fiber. Taking out and drying at room temperature.

Comparative example 2

Putting polylactic acid in a vacuum oven at 80 ℃ for drying for 24 hours, taking 10g of dried polylactic acid and 2g of anionic modified carbon black, fully stirring and mixing the polylactic acid and the anionic modified carbon black in a flask, adding the mixture into a double-cone micro mixing mill, adjusting the rotating speed of a screw to 60rpm, raising the temperature of a left plate and a right plate to 190 ℃, drawing the polylactic acid to a small winder after the polylactic acid is melted and extruded, adjusting the winding speed to 10m/min, taking down the fiber wound on the winder after a period of time, placing the fiber in a water bath kettle at 70 ℃ for drawing for 30 seconds, improving the orientation degree of the fiber and extending the length of the fiber to 2 times of the original fiber. Taking out and drying at room temperature.

The preparation method of the anion modified carbon black comprises the following steps: 2.5g of silane coupling agent and 5g of carbon black are added into an alcohol-water mass ratio of 9: 1 in 100g of mixed solvent, performing ultrasonic treatment for 30min, transferring the mixture to a water bath kettle at 40 ℃, preserving heat, stirring and reacting for 24h to obtain the silane coupling agent modified carbon black. And then 1g of silane coupling agent modified carbon black is taken to be dispersed into ethanol, 25g of sodium p-styrene sulfonate is added under the condition of continuous stirring, 5g of ammonium persulfate is added dropwise after the temperature is raised, and the anionic modified carbon black is obtained after the reaction is kept for a period of time.

Comparative example 3

Referring to example 1, the winding process was omitted, and the melt-extruded fiber was directly drawn in a water bath at 70 ℃ for 30 seconds to increase the degree of orientation of the fiber and extend the length thereof to 2 times that of the fibril. Taking out and drying at room temperature.

Comparative example 4

Referring to example 1, the fiber was melt-extruded, wound, cooled, solidified, oiled, drawn on a drawing plate for 30 seconds to increase the degree of orientation of the fiber and elongate the length of the fiber by 2 times the original fiber. Taking out and drying at room temperature.

The specific results of the fibers obtained in the above comparative examples are shown in Table 5.

TABLE 5 Performance results for fibers obtained in the comparative examples

Results of the experiment	Strength (N/tex)	Fineness (micrometer)	K/S	CMC DE
					Comparative example 1	0.26	48	21.7	1.44
Comparative example 2	0.11	48	22.462	1.68
					Comparative example 3	0.20	48	21.22	1.83
Comparative example 4	0.10	48	21.9	0.70

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. The preparation method of the black polylactic acid fiber is characterized in that nonionic modified carbon black and polylactic acid are subjected to melt extrusion, then a winding machine is used for winding, and then drafting is carried out to obtain the black polylactic acid fiber; the mass part of the nonionic modified carbon black relative to the polylactic acid is 1.5-2.5%; the drafting time is 20-120 s;

the winding speed of the winding machine is 20-30 m/min;

the drafting is carried out in a water bath at 65-95 ℃;

the non-ionic modified carbon black is prepared by carrying out surface treatment on carbon black by adopting a silane coupling agent to obtain pretreated carbon black; then adding a nonionic comonomer to modify the pretreated carbon black to obtain nonionic modified carbon black; wherein the non-ionic comonomer comprises one or more of lactide, ethylene terephthalate, trimethylene terephthalate, butylene terephthalate and butylene succinate.

2. The method of claim 1, wherein the melt extrusion temperature is 170-210 ℃.

3. The method according to claim 1, wherein the draft is 1.5 to 3 times.

4. Black polylactic acid fiber prepared by the method of any one of claims 1 to 3.

5. A textile made of the black polylactic acid fiber according to claim 4.

6. Use of the black polylactic acid fiber according to claim 4 in the field of clothing.