阅读说明：本技术 一种再生纤维素强力丝及其制备方法 (Regenerated cellulose strong yarn and preparation method thereof ) 是由 崔世强 娄善好 元伟 马君志 张玉梅 刘长军 战云 于 2019-09-29 设计创作，主要内容包括：本发明提供一种再生纤维素强力丝,所述再生纤维素强力丝,原纤化指数≤3；本发明还提供一种再生纤维素强力丝的制备方法,包括制备纺丝溶液、纺丝、拉伸；所述拉伸,纺丝得到的丝束经过空气段、然后进行第一级拉伸、第二级拉伸或更多级数拉伸。本发明制备的再生纤维素强力丝,可以同时满足高强高模且低原纤化,制得的再生纤维素的干态断裂强度为4.5~6.0cN/dtex,湿态断裂强度为3.8~5.5cN/dtex,干态模量≥90cN/dtex,原纤化指数≤3。(The invention provides a regenerated cellulose strong yarn, which has a fibrillation index less than or equal to 3, and a preparation method of the regenerated cellulose strong yarn, comprising the steps of preparing a spinning solution, spinning and stretching, wherein tows obtained by spinning pass through an air section and then are stretched in the first stage, the second stage or more stages, the prepared regenerated cellulose strong yarn can simultaneously meet the requirements of high strength, high modulus and low fibrillation, the dry breaking strength of the prepared regenerated cellulose is 4.5 ~ 6.0.0 cN/dtex, the wet breaking strength is 3.8 ~ 5.5.5 cN/dtex, the dry modulus is more than or equal to 90cN/dtex, and the fibrillation index is less than or equal to 3.)

1. The regenerated cellulose strong yarn is characterized in that the fibrillation index of the regenerated cellulose strong yarn is less than or equal to 3.

2. The regenerated cellulose strong yarn according to claim 1, characterized in that the regenerated cellulose strong yarn has a dry strength of 4.5 ~ 6.0.0 cN/dtex, a wet strength of 3.8 ~ 5.5.5 cN/dtex, and a dry modulus of 90cN/dtex or more.

3. A preparation method of regenerated cellulose strong yarn is characterized by comprising the steps of preparing spinning solution, spinning and stretching; and (3) drawing, namely, passing the tows obtained by spinning through an air section, and then carrying out primary drawing, secondary drawing or more-stage drawing.

4. The method for preparing regenerated cellulose strong yarn according to claim 3, characterized in that the tow obtained by drawing and spinning is passed through an air section and then subjected to first drawing and second drawing; the length of the air section is 10-300mm, and the retention time is 0.03-4.0 s.

5. The method of claim 4, wherein the NMMO concentration in the coagulation bath of the first stage drawing is 0% -40%, the temperature is 0-30 ℃, the drawing ratio is 1-10 times, the one-roll drawing speed is 5-20m/min, and the retention time is 0.05-25 s.

6. The method of claim 4, wherein the first drawing step produces a first drawn yarn having a composition of NMMO: 15% -40%, cellulose: 5% -25%, water: 45% -60%; the first-stage drawn yarn has the strength of 1.1-2.3cN/dtex, the elongation at break of 20-55 percent and the birefringence of 0.021-0.055.

7. The method of claim 4, wherein the concentration of NMMO in the secondary drawing and coagulation bath is 0% -30%, the temperature is 0-60 ℃, the drawing ratio is 1-5 times, the two-roll drawing speed is 10-60m/min, and the retention time is 2.0-12 s.

8. The method of claim 4, wherein the second drawing step produces a second drawn yarn having a composition of NMMO: 5% -15%, cellulose: 12% -45%, water: 40% -80%; the second-stage drawn yarn has the strength of 3.0-5.3cN/dtex, the elongation at break of 10-25 percent and the birefringence of 0.035-0.072.

9. The method of claim 3, wherein the regenerated cellulose strong yarn is produced by a method comprising the steps of,

the spinning solution contains 5-14% of cellulose, 75-80% of NMMO and the balance of water.

10. The method of claim 3, wherein the regenerated cellulose strong yarn is produced by a method comprising the steps of,

the spinning temperature is 85-105 ℃, and the diameter of a spinneret orifice is 0.05mm-0.2 mm.

Technical Field

The invention belongs to the field of fiber manufacturing, and relates to a regenerated cellulose strong yarn and a preparation method thereof.

Background

The regenerated cellulose fiber prepared by taking NMMO as a solvent has the advantages of high strength and modulus, especially high wet strength and wet modulus, similar dry and wet strength, good dimensional stability, good heat resistance, environment-friendly production process and the like; however, the fibrillated nature of Lyocell fibers presents problems not only for dyeing, wearing and washing of fabrics; but also can influence the application stability of the Lyocell fiber as the industrial high-strength yarn.

At present, aiming at the problem that Lyocell fibers are easy to fibrillate, the fibers are mainly subjected to post-treatment, and alkali liquor, resin and a crosslinking agent are mainly used for treating the fibers. The method realizes the industrial production of the Lyocell fiber with the anti-fibrillation performance.

Patent CN95192563.6A reports that a crosslinking agent having three acrylamide groups, preferably 1,3, 5-triacrylate hexahydro-1, 3, 5-triazine, reacts with wet solution spun cellulose fibers to reduce their tendency to fibrillate. Patent CN98801507.2A reports a method of reducing the fibrillation tendency of solution spun cellulose fibers with a textile auxiliary having two reactive groups, preferably a cross-linking agent of the sodium salt of 2, 4-dichloro-6-hydroxytriazine. However, the cross-linking agents used in these processes are complicated to synthesize and expensive, and the cross-linking agents are not easy to store for a long time and are easy to hydrolyze during use, thereby affecting the efficiency of the cross-linking reaction and the effect of the fibrillation resistance of the fibers.

Patent CN103306136A reports a cross-linking agent composition, which is prepared by mixing oligomeric polybasic acid with molecular weight of 400-1000 and C2-C6 polybasic acid in a certain proportion, and solves the problems of complex synthesis, high price, difficult storage and easy hydrolysis of the cross-linking agent, but in the process of treating the fiber, the treatment temperature is high, the treatment time is long, and the mechanical properties of the fiber are greatly affected.

EP-A-494851 describes ｃA process for drawing extruded and coagulated cellulose which is substantially stress-free, in which process the point is that the freshly extruded filaments are not drawn; this process is similar to a plastic deformation process in which the starting material, i.e., undrawn Lyocell filaments, has a rubbery consistency. However, the mechanical properties of the fibers produced according to the process of this patent do not meet the requirements of today.

Patent CN100410430C provides a method for post-drawing Lyocell fiber, which is to post-draw the filament after passing through an air zone and coagulating and drawing in a coagulating bath, and then drawing the filament under a certain tension under heat treatment conditions, which can improve the textile properties of Lyocell fiber, increase the mechanical strength, especially the wet modulus of the fiber, to 350CN/tex, but as a cellulose strong yarn, the mechanical properties are not satisfactory, and the problem of fibrillation of cellulose fiber is not improved.

Literature studies have shown that Lyocell spinning processes, including dope concentration, coagulation bath temperature concentration, air space length, spinning speed and draw ratio, all have an effect on the fibrillation of Lyocell fibers. The aim of reducing the fibrillation of the Lyocell fibers can be achieved by adjusting the spinning process conditions, but the mechanical property of the fibers can be influenced, the fibrillation cannot be reduced, and the Lyocell fibers with higher strength and modulus can be obtained.

In summary, the method for improving the fiber antigen capability of the Lyocell fiber in the prior art has the following technical problems:

(1) the method adopting the cross-linking agent for treatment has the advantages of high treatment temperature, long treatment time, great influence on the mechanical properties of the fibers, reduction in the mechanical properties of the fibers such as breaking strength and elongation; meanwhile, the high-temperature crosslinking treatment makes the fiber become hard and brittle and loses the original softness.

(2) The fibrillation of the Lyocell fiber can be reduced by adjusting the spinning process, but the mechanical property of the fiber is influenced at the same time, and the technology of simultaneously meeting the requirements of high strength, high modulus and antigen fibrillation is not reported.

Disclosure of Invention

In order to solve the defects in the prior art, the invention adopts a novel spinning technical method and a two-stage stretching dry-jet wet spinning process to prepare the Lyocell fiber strong yarn, and realizes the following purposes:

(1) improving the strength and modulus of the Lyocell fiber;

(2) reducing the degree of fibrillation of the Lyocell fibers;

(3) the soft performance of the Lyocell fiber is maintained.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the regenerated cellulose strong yarn has dry breaking strength of 4.5 ~ 6.0.0 cN/dtex, wet breaking strength of 3.8 ~ 5.5.5 cN/dtex, dry modulus not less than 90cN/dtex, and fibrillation index not more than 3.

The following is a further improvement of the above technical solution:

the regenerated cellulose strong yarn is Lyocell fiber.

A preparation method of regenerated cellulose strong yarn comprises the following steps:

(1) preparation of the spinning solution

Cellulose pulp with the polymerization degree of 400-1200 and NMMO solution are mixed, dehydrated and dissolved to prepare cellulose spinning solution with the concentration of 5-14%.

The degree of polymerization of the cellulose pulp is preferably 500-600;

the concentration of the NMMO solution is preferably 45-55 wt%;

the content of cellulose in the spinning solution is preferably 8-12%, the NMMO content is 76-80%, and the water content is 10-14%.

(2) Spinning

Then extruding the mixture through a spinneret orifice to carry out spinning; the diameter of the spinneret orifice is 0.05mm-0.2mm, preferably 0.1mm, and the spinning temperature is 85-105 ℃, preferably 85-95 ℃.

(3) Stretching

Passing through an air section, a first stage of stretching and a second stage of stretching;

the length of the air section is 10-300mm, preferably 50-100mm, and the residence time of the air section is 0.03-4.0s, preferably 0.3-0.6 s.

The process conditions of the first stage drawing are as follows: the coagulating bath is an NMMO aqueous solution with the mass concentration of 0-40%, the temperature of the coagulating bath is 0-30 ℃, the stretching ratio is 1-10 times, the retention time is 0.05-25s, and the one-roll stretching speed is 5-20 m/min; the first-stage drawn yarn is obtained by the following three components: NMMO 15-40%, cellulose 5-25%, water 45-60%, strength 1.1-2.3cN/dtex, elongation at break 20-55%, birefringence 0.021-0.055.

Preferably: the coagulating bath is 18-25% NMMO water solution, the temperature of the coagulating bath is 20-22 deg.C, the stretching time is 3-4 times, the retention time is 0.1-1.5s, and the one-roll stretching speed is 8-12 m/min; the first-stage drawn yarn is obtained by the following three components: NMMO 29-36%, cellulose 10-15%, water 54-56%, strength 1.75-1.95cN/dtex, elongation at break 20-22%, birefringence 0.032-0.04.

The residence time in the first stage drawing is further preferably 0.1 s.

The second-stage stretching process conditions are as follows: the coagulating bath is NMMO aqueous solution with mass concentration of 0-30%, the temperature is 0-60 ℃, the stretching magnification is 1-5 times, the retention time is 2-12s, and the two-roller stretching speed is 10-60 m/min; the obtained second-stage drawn yarn comprises the following three components in percentage by weight: NMMO: 5% -15%, cellulose: 12% -45%, water: 40-80%, strength of 3.0-5.3cN/dtex, elongation at break of 10-25%, and birefringence of 0.035-0.072.

Preferably: the second-stage stretching process conditions are as follows: the coagulating bath is 10% NMMO water solution, the temperature is 15-20 ℃, the stretching ratio is 2-2.5 times, the retention time is 5s, and the two-roller stretching speed is 20-25 m/min;

the obtained second-stage drawn yarn comprises the following three components in percentage by weight: NMMO: 10% -12%, cellulose: 12% -21%, water: 67-78%, strength 4.4-4.7cN/dtex, elongation at break 15-17%, and birefringence index 0.059-0.063.

(4) Post-treatment

The fiber obtained by the second or more stages of stretching is washed, hot stretched and heat-set, and the obtained fiber titer is 1.0-5.0 dtex, the dry strength is 4.5 ~ 6.0.0 cN/dtex, the wet strength is 3.8 ~ 5.5.5 cN/dtex, the dry modulus is more than or equal to 90cN/dtex, the elongation at break is 5-15%, the birefringence is 0.045-0.086, and the titer index is less than or equal to 3, preferably the fiber is 2-2.3dtex, the dry strength is 4.7 ~ 4.9.9 cN/dtex, the wet strength is 3.8 ~ 4.1.1 cN/dtex, the dry modulus is 93-96cN/dtex, the elongation at break is 12-14%, the birefringence is 0.073-0.075, and the fibrillation index is 2-3.

A regenerated cellulose strong yarn is prepared by extruding cellulose solution from a spinneret orifice, entering a coagulating bath through an air gap section, performing primary drawing, and then continuously performing secondary or more-stage drawing to obtain high-strength, high-modulus and low-fibrillation regenerated cellulose fibers; the high-strength yarn is prepared by a two-stage drawing dry-jet wet spinning process, compared with a primary drawing process, the secondary drawing is increased, the process condition of the first-stage drawing is changed, the fibrillation index of the fiber is reduced, and the drawing performance of the Lyocell solidified yarn in the second-stage drawing is improved. In the first stage drawing process, the stress borne by the filament and the orientation degree of the filament are reduced by adopting lower drawing multiplying power and spinning speed in the first stage drawing process, so that the fibrillation index of the filament is reduced, and the re-drawing capability of the fiber in the second stage is improved; the higher concentration of the first coagulation bath and the shorter coagulation time are adopted, the residual quantity of NMMO in the Lyocell coagulated filament is improved, the interaction among cellulose molecules is weakened, and the redrawing performance of the Lyocell coagulated filament in the second section is ensured; in the second stage drawing process, the concentration and the temperature of the second coagulating bath and the drawing ratio in the second stage are adjusted, so that the Lyocell coagulated filaments are further drawn and completely coagulated and formed, the orientation degree of the Lyocell fibers is improved, and the strength and the modulus of the fibers are improved.

Compared with the prior art, the invention has the following beneficial effects:

(1) the regenerated cellulose fiber prepared by the invention has higher strength and modulus, and can meet the performance requirements of cellulose strong yarn:

the titer of the regenerated cellulose fiber prepared by the invention is 1.0-5.0 dtex, the dry strength is 4.5 ~ 6.0.0 cN/dtex, the wet strength is 3.8 ~ 5.5.5 cN/dtex, the dry modulus is more than or equal to 90cN/dtex, the elongation at break is 5-15%, and the birefringence is 0.045-0.086.

(2) The regenerated cellulose fiber prepared by the method meets the requirements of high strength and high modulus, simultaneously reduces the fibrillation degree of the fiber, and the fibrillation index is less than or equal to 3.

(3) The preparation method of the regenerated cellulose strong yarn can be used for preparing the regenerated cellulose strong yarn with low fibrillation, and the application field of the regenerated cellulose fiber is expanded and enriched.

Detailed Description

The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.