Regenerated cellulose multifilament for cord thread and preparation method of regenerated cellulose multifilament

Abstract

The invention belongs to the field of fiber preparation, and particularly relates to regenerated cellulose multifilament for a cord thread and a preparation method of the regenerated cellulose multifilament. According to the regenerated cellulose multifilament prepared by the method, a cellulose solution is extruded from a spinneret orifice, enters a coagulating bath through an air gap section, then is subjected to multi-stage gradient water washing, and then is subjected to leaching, oiling and heat setting, so that the regenerated cellulose multifilament with low breaking strength and breaking elongation variation coefficient (CV (%)) is prepared. The variable coefficient (CV (%)) of the breaking strength and the breaking elongation of the regenerated cellulose multifilament is reduced, and the performance requirements of the regenerated cellulose multifilament for cord threads are met.

Description

Technical Field

[0001] The invention belongs to the field of fiber preparation, and in particular relates to a regenerated cellulose multifilament for a cord and a preparation method thereof. Background Art

[0002] Regenerated cellulose fiber has a unique position in the field of tire cords due to its excellent dimensional stability, especially its ability to maintain good dimensional stability under high temperature conditions, and its good adhesion to rubber. It is mainly used in high-speed tire meridians. At present, the regenerated cellulose fiber used in tire cords is mainly viscose strong yarn, but the existing production capacity of viscose strong yarn cannot meet the market demand. At the same time, due to the large pollution in the production process of viscose strong yarn, the increase in its production capacity is limited. The regenerated cellulose multifilament prepared by the ionic liquid solvent method adopts a direct dissolution method. Dissolution and regeneration are physical processes. The solvent can be recycled and reused, opening up a way for the clean preparation of regenerated cellulose multifilament. In addition, the regenerated cellulose multifilament prepared by the ionic liquid solvent method has the characteristics of high strength, high modulus and similar dry and wet strength, which makes it have the potential to be used in tire cords.

[0003] At present, ionic liquid solvent-based regenerated cellulose fiber products have been widely used in civilian fields, such as clothing, home textiles, and medical treatment. However, in industrial fields such as tire cord, the performance requirements for regenerated cellulose multifilament are obviously different from those in the civilian field. In addition to requiring higher strength and modulus, its various performance indicators should also have higher uniformity and stability to ensure stable performance when used as cord material. The uniformity and stability of various performance indicators can be expressed by the coefficient of variation (CV (%)).

[0004] Patent CN101578401B proposes to adjust the coagulation coefficient by adjusting the air section and the coagulation bath temperature to achieve the purpose of reducing the coefficient of variation of the cross-sectional diameter of each single filament in the regenerated cellulose multifilament. The method disclosed in the patent reduces the coefficient of variation of the cross-sectional diameter of each single filament in the regenerated cellulose multifilament and improves the uniformity of the cross-sectional diameter of each single filament in the multifilament. However, it does not improve the uniformity of various performance indicators of the regenerated cellulose multifilament, such as breaking strength, breaking elongation and modulus.

[0005] Other patents US6773648 disclose a regenerated cellulose fiber, the coefficient of variation of the cross-sectional diameter in the fiber length direction (CV(%)) is 6% to 17%, and the coefficient of variation of the cross-sectional diameter between the fibers (CV(%)) is 10% to 22%, but such a coefficient of variation is still large, and the regenerated cellulose fiber is a short fiber, which is not suitable for use as a tire cord.

[0006] Patent CN117535804A discloses a method and equipment for preparing regenerated cellulose industrial yarn, which uses gradient coagulation to increase the residual solvent in the yarn and shrink the yarn under high-temperature coagulation conditions to improve the elongation at break of the product; at the same time, the structural difference of a single yarn along the radial direction is reduced to ensure the performance of the product. However, the high-temperature coagulation condition, although it provides conditions for the movement of cellulose molecular segments, will also accelerate the rate of double diffusion, and cannot ensure the stability of the molding conditions of the entire yarn bundle, and thus cannot ensure the stability of the performance of the final regenerated cellulose multifilament.

[0007] Although many patents disclose the ionic liquid solvent method for preparing regenerated cellulose fibers, the spinning process of regenerated cellulose by the ionic liquid solvent method, including the concentration of spinning solution, the length of air segment, the coagulation bath conditions, the washing conditions, the spinning speed and the stretching ratio, all have an impact on the performance of regenerated cellulose fibers, and the performance of regenerated cellulose fibers obtained under different spinning process conditions is also different. For regenerated cellulose multifilament for cord, in addition to having certain requirements such as breaking strength and breaking elongation, the uniform stability of its various performance indicators, that is, the low coefficient of variation (CV (%)) is also a very important indicator, which determines its performance and stability in use when applied to cord.

[0008] In summary, the prior art methods for improving the performance of regenerated cellulose multifilaments for use in cords have the following problems: the uniformity of the cross-sectional diameters of the individual filaments in the multifilaments is improved, but the uniformity of the performance indicators of the regenerated cellulose multifilaments, such as breaking strength, breaking elongation, and modulus, is not improved. Summary of the invention

[0009] The main object of the present invention is to provide a regenerated cellulose multifilament for cord with reduced coefficient of variation (CV (%)) of breaking strength and breaking elongation of the regenerated cellulose multifilament and a preparation method thereof, so as to meet the performance requirements for the cord.

[0010] In order to solve the shortcomings of the prior art, the present invention adopts a new spinning technology route, adopts a mild coagulation bath condition and a multi-stage gradient water washing technology route to prepare a regenerated cellulose multifilament, thereby achieving the following purposes: reducing the coefficient of variation (CV (%)) of the breaking strength and elongation at break of the regenerated cellulose multifilament, and improving the uniformity of the breaking strength and elongation at break of each single filament of the regenerated cellulose multifilament.

[0011] To achieve the above objectives, the first aspect of the present invention adopts the following technical scheme: a regenerated cellulose multifilament with a fineness of 800-3000 dtex, a breaking strength of 4.5-6 cN / dtex, a breaking strength CV (%) ≤2.5%, a breaking elongation of 8-15%, a breaking elongation CV (%) ≤2.5%, a dry heat shrinkage rate at 177°C and 0.01 cN / dtex of ≤0.7%, and a dry heat shrinkage rate CV (%) ≤2.5% at 177°C and 0.01 cN / dtex; the regenerated cellulose multifilament is composed of 100-3000 single filaments.

[0012] The second aspect of the present invention is to disclose a method for preparing the aforementioned regenerated cellulose multifilament, comprising the following steps: (1) Preparation of spinning solution; (2) Spinning; (3) Coagulation: After the extruded filaments pass through the air section, they enter the coagulation bath. The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 0-60%, the coagulation bath temperature is 0-30 °C, the stretching ratio is 1-5 times, and the stretching speed is 10-200 m / min. (4) Multi-level gradient water washing: The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: an ionic liquid aqueous solution with a composition of 10-30% by mass, a temperature of 10-50°C, and a stretching speed of 10-200 m / min; The conditions of the second-stage water washing bath are: the composition is an ionic liquid aqueous solution with a mass fraction of 10-25%, the temperature is 10-50°C, and the stretching speed is 10-200 m / min; The third-stage water washing bath conditions are: an ionic liquid aqueous solution with a composition of 5-20% by mass, a temperature of 10-50°C, and a stretching speed of 10-200 m / min; The fourth-stage water washing bath conditions are: an ionic liquid aqueous solution with a composition of 5-15% by mass, a temperature of 10-50° C., and a stretching speed of 10-200 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 0-10%, the temperature is 10-50°C, and the stretching speed is 10-200 m / min; The ionic liquid concentration of each level of water washing bath is determined according to the ionic liquid content in the tow when entering each level of water washing bath; the ionic liquid concentration (i.e., mass content, mass fraction) of each level of water washing bath is 5-10% lower than the ionic liquid concentration (i.e., mass content, mass fraction) in the tow when entering the water washing bath of that level; (5) Post-treatment to obtain regenerated cellulose multifilament; the regenerated cellulose multifilament consists of 600-2000 single filaments.

[0013] In a preferred embodiment, in step (3), the coagulation bath is an aqueous solution of ionic liquid with a mass fraction of 30-50%, the coagulation bath temperature is 5-20°C, the stretching ratio is 1-2 times, and the stretching speed is 50-150 m / min.

[0014] In a preferred embodiment, in step (4), the first-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 20-30%, the water washing bath temperature is 30-50 ° C, and the stretching speed is 50-150 m / min; The second-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 15-25%, the water washing bath temperature is 30-50 °C, and the stretching speed is 50-150 m / min; The third-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 10-20%, the water washing bath temperature is 30-50 ℃, and the stretching speed is 50-150 m / min; The fourth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 5-10%, the water washing bath temperature is 30-50 °C, and the stretching speed is 50-150 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 0-5%, the water washing bath temperature is 30-50°C, and the stretching speed is 50-150 m / min.

[0015] In step (1), cellulose pulp with a degree of polymerization of 500-1500 and an ionic liquid are mixed, dehydrated and dissolved to prepare a cellulose spinning solution with a concentration of 5-20wt%; the ionic liquid is one or more of 1-butyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium acetate.

[0016] Preferably, in step (1), the degree of polymerization of the cellulose pulp is 700-1000; and the solid content of cellulose in the spinning solution is 8-15wt%.

[0017] In step (2), the prepared cellulose spinning stock solution is extruded through a spinneret for spinning; the number of spinneret holes is 100-3000 holes; the diameter of the spinneret holes is 0.04-0.2 mm; and the spinning temperature is 80-120°C.

[0018] Furthermore, in step (2), the number of spinneret holes is 600-2000 holes; the diameter of the spinneret holes is 0.05-0.08 mm; and the spinning temperature is 95-110°C.

[0019] In step (5), the filaments are washed with multi-stage gradient water, and then rinsed, oiled, and heat-set to obtain regenerated cellulose multifilaments.

[0020] The third aspect of the present invention is to provide a cord made from the aforementioned regenerated cellulose multifilament.

[0021] The regenerated cellulose multifilament prepared by the present invention is obtained by extruding a cellulose solution from a spinneret hole, passing through an air gap section into a coagulation bath, and then undergoing multi-stage gradient water washing, followed by elution, oiling, and heat setting, to obtain a regenerated cellulose multifilament with low breaking strength and breaking elongation coefficient of variation (CV (%)); the regenerated cellulose multifilament is obtained by a dry-jet wet spinning process comprising a coagulation bath with mild molding conditions and a five-stage water washing bath with multi-stage gradient water washing. During the coagulation and water washing process, the tow mainly undergoes a double diffusion process of solvent (ionic liquid) and non-solvent (water). For industrial regenerated cellulose industrial yarn, it is usually composed of hundreds to thousands of single filaments. Therefore, during the molding process, the core of the tow ( Figure 1 The green part in the middle) and the outer part of the tow ( Figure 1 The stability of the molding conditions (the blue part in the middle) is particularly important for the uniformity of the entire bundle. The filaments in the outer ring of the tow are more likely to contact the coagulation bath and the water washing bath, and the double diffusion process occurs first. If the difference between the solvent concentration inside the tow and the concentration of each bath liquid is too large, it will lead to the rapid molding of the outer ring of the tow, and at the same time, the bath solvent concentration at the outer ring of the tow will rise rapidly and instantly, increasing the local ionic liquid concentration of the core tow molding, which will cause the outer ring of the tow to be molded faster than the core, reducing the uniformity of the final fiber. Compared with the existing process, the present invention (1) uses a high-concentration and low-temperature coagulation bath condition, which reduces the double diffusion rate of the fiber bundle in the coagulation bath, weakens the effect of the local bath liquid instantaneous concentration rising rapidly due to the double diffusion of the outer ring of the fiber bundle first, reduces the local ionic liquid concentration difference between the outer ring and the core of the fiber bundle during molding, and improves the uniformity of the overall molding of the fiber bundle; (2) adopts a multi-stage gradient water washing technology, and sets a suitable ionic liquid concentration in each stage of the water washing bath according to the ionic liquid content in the fiber bundle when entering each stage of the water washing bath. The ionic liquid concentration of each stage of the water washing bath is 5-10% lower than the ionic liquid concentration in the fiber bundle when entering each stage of the water washing bath, so as to delay the double diffusion process of the fiber bundle in each stage of the water washing, reduce the ionic liquid concentration difference between the outer ring and the core of the fiber bundle, and achieve the purpose of removing the ionic liquid in the fiber bundle while ensuring uniform fiber molding.

[0022] Compared with existing technologies: (1) The present invention prepares regenerated cellulose multifilament with a fineness of 800-3000 dtex, a breaking strength of 4.5-6 cN / dtex, a breaking strength CV (%) ≤2.5%, a breaking elongation of 8-15%, a breaking elongation CV (%) ≤2.5%, a dry heat shrinkage at 177°C and 0.01 cN / dtex of ≤0.7%, and a dry heat shrinkage at 177°C and 0.01 cN / dtex of CV (%) ≤2.5%.

[0023] (2) The regenerated cellulose industrial yarn prepared by the present invention can meet the application requirements of cord. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A cross-sectional view of a solidified filament bundle. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0026] The following is a specific solution of the technical route of the present invention: (1) Preparation of spinning solution: The cellulose pulp with a polymerization degree of 500-1500 and the ionic liquid are mixed, dehydrated and dissolved to prepare a cellulose spinning stock solution with a concentration of 5-20wt%.

[0027] The dissolution process is a wet dissolution process; The degree of polymerization of the cellulose pulp is preferably 700-1000; The ionic liquid is preferably 1-butyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium acetate.

[0028] The solid content of cellulose in the spinning solution is preferably 8-15wt%.

[0029] (2) Spinning The prepared cellulose spinning stock solution is extruded through a spinneret for spinning; the number of spinneret holes is 100-3000 holes, preferably 600-2000 holes; the diameter of the spinneret holes is 0.04-0.2 mm, preferably 0.05-0.08 mm; the spinning temperature is 80-120°C, preferably 95-110°C.

[0030] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; The air section length is 5-500 mm, preferably 20-50 mm; The coagulation bath conditions are: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 0-60%, the coagulation bath temperature is 0-30°C, the stretching ratio is 1-5 times, and the stretching speed is 10-200 m / min; preferably: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 30-50%, the coagulation bath temperature is 5-20°C, the stretching ratio is 1-2 times, and the stretching speed is 50-150 m / min; (4) Multi-stage gradient water washing The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 10-30%, the temperature is 10-50°C, and the stretching speed is 10-200 m / min; preferably: the water washing bath is an ionic liquid aqueous solution with a mass fraction of 20-30%, the water washing bath temperature is 30-50°C, and the stretching speed is 50-150 m / min; The second-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 10-25%, the temperature is 10-50°C, and the stretching speed is 10-200 m / min; preferably: the water washing bath is an ionic liquid aqueous solution with a mass fraction of 15-25%, the water washing bath temperature is 30-50°C, and the stretching speed is 50-150 m / min; The third-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 5-20%, the temperature is 10-50°C, and the stretching speed is 10-200 m / min; preferably: the water washing bath is an ionic liquid aqueous solution with a mass fraction of 10-20%, the water washing bath temperature is 30-50°C, and the stretching speed is 50-150 m / min; The fourth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 5-15%, the temperature is 10-50°C, and the stretching speed is 10-200 m / min; preferably: the water washing bath is an ionic liquid aqueous solution with a mass fraction of 5-10%, the water washing bath temperature is 30-50°C, and the stretching speed is 50-150 m / min; The fifth stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 0-10%, the temperature is 10-50°C, and the stretching speed is 10-200 m / min; preferably: the water washing bath is an ionic liquid aqueous solution with a mass fraction of 0-5%, the water washing bath temperature is 30-50°C, and the stretching speed is 50-150 m / min; (5) Post-processing The filaments are washed with multi-stage water and gradient water, and then washed, oiled and heat-set to obtain regenerated cellulose multifilaments. The obtained regenerated cellulose industrial filaments have a fineness of 800-3000 dtex, a breaking strength of 4.5-6 cN / dtex, a breaking strength CV (%) ≤2.5%, a breaking elongation of 8-15%, a breaking elongation CV (%) ≤2.5%, a dry heat shrinkage rate at 177°C and 0.01 cN / dtex of ≤0.7%, and a dry heat shrinkage rate at 177°C and 0.01 cN / dtex of CV (%) ≤2.5%; preferably, the fineness is 1000-2000 dtex, the breaking strength is 4.5-5.5 cN / dtex, the breaking strength CV (%) ≤2.5%, the breaking elongation is 8-10%, the breaking elongation CV (%) ≤2.5%, and the drying temperature is 177°C and 0.01 The dry heat shrinkage rate under cN / dtex conditions is ≤0.6%, and the dry heat shrinkage rate CV (%) under 177 ℃ and 0.01 cN / dtex conditions is ≤2.5%.

[0031] Example 1 A method for preparing regenerated cellulose multifilament for cord (1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 700 and 1-butyl-3-methylimidazolium chloride are mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0032] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 10wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 660, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 95 °C.

[0033] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 40%, the coagulation bath temperature is 15 °C, the stretching ratio is 1.5 times, and the stretching speed is 80 m / min; (4) Multi-level gradient water washing The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: the composition is 30% by mass of ionic liquid aqueous solution, the temperature is 40 °C, and the stretching speed is 80 m / min; The conditions of the second-stage water washing bath are: the composition is 20% by mass of ionic liquid aqueous solution, the temperature is 40 °C, and the stretching speed is 80 m / min; The third-stage water washing bath conditions are: composition of 15% by mass ionic liquid aqueous solution, temperature of 40 °C, and stretching speed of 80 m / min; The fourth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 10%, the temperature is 40 °C, and the stretching speed is 80 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 5%, the temperature is 40 °C, and the stretching speed is 80 m / min; (5) Post-processing The filaments were washed with gradient water, then rinsed, oiled and heat-set to obtain regenerated cellulose industrial yarns. The regenerated cellulose industrial yarns had a fineness of 1650 dtex, a breaking strength of 4.8 cN / dtex, a breaking strength CV (%) of 2.3%, an elongation at break of 9%, an elongation at break CV (%) of 2.1%, a dry heat shrinkage at 177°C and 0.01 cN / dtex of 0.5%, and a dry heat shrinkage CV (%) of 1.7% at 177°C and 0.01 cN / dtex.

[0034] The ionic liquids in this embodiment are all 1-butyl-3-methylimidazolium chloride.

[0035] Example 2 A method for preparing regenerated cellulose multifilament for cord (1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 800 and 1-allyl-3-methylimidazolium chloride were mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0036] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 10wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 1000, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 90 °C.

[0037] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 50%, the coagulation bath temperature is 20 °C, the stretching ratio is 1.8 times, and the stretching speed is 120 m / min; (4) Multi-stage gradient water washing The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: composition of 30% by mass ionic liquid aqueous solution, temperature of 50 °C, and stretching speed of 120 m / min; The conditions of the second-stage water washing bath are: the composition is an ionic liquid aqueous solution with a mass fraction of 23%, the temperature is 50 ℃, and the stretching speed is 120 m / min; The third-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 16%, the temperature is 50 °C, and the stretching speed is 120 m / min; The fourth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 12%, the temperature is 50 °C, and the stretching speed is 120 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 5%, the temperature is 50 °C, and the stretching speed is 120 m / min; (5) Post-processing The filaments were washed with gradient water, and then rinsed, oiled and heat-set to obtain regenerated cellulose industrial yarn. The regenerated cellulose industrial yarn had a fineness of 2000 dtex, a breaking strength of 4.9 cN / dtex, a breaking strength CV (%) of 2.2%, an elongation at break of 8.3%, an elongation at break CV (%) of 2.1%, a dry heat shrinkage at 177 °C and 0.01 cN / dtex of 0.6%, and a dry heat shrinkage CV (%) of 177 °C and 0.01 cN / dtex of 1.8%.

[0038] The ionic liquids in this embodiment are all 1-allyl-3-methylimidazolium chloride.

[0039] Example 3 A method for preparing regenerated cellulose multifilament for cord (1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 800 and 1-ethyl-3-methylimidazole acetate were mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0040] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 13wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 1000, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 85 °C.

[0041] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 40%, the coagulation bath temperature is 15 °C, the stretching ratio is 1.7 times, and the stretching speed is 100 m / min; (4) Multi-stage gradient water washing The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 28%, the temperature is 50 °C, and the stretching speed is 100 m / min; The conditions of the second-stage water washing bath are: the composition is an ionic liquid aqueous solution with a mass fraction of 17%, the temperature is 50 °C, and the stretching speed is 100 m / min; The third-stage water washing bath conditions are: composition of 13% mass fraction of ionic liquid aqueous solution, temperature of 50 °C, stretching speed of 100 m / min; The fourth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 8%, the temperature is 50 °C, and the stretching speed is 100 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 3%, the temperature is 50 °C, and the stretching speed is 100 m / min; (5) Post-processing The filaments were washed with gradient water, and then rinsed, oiled and heat-set to obtain regenerated cellulose industrial yarn. The regenerated cellulose industrial yarn had a fineness of 1800 dtex, a breaking strength of 4.7 cN / dtex, a breaking strength CV (%) of 2.1%, an elongation at break of 9.7%, an elongation at break CV (%) of 2.3%, a dry heat shrinkage at 177 °C and 0.01 cN / dtex of 0.5%, and a dry heat shrinkage CV (%) of 177 °C and 0.01 cN / dtex of 1.9%.

[0042] The ionic liquids in this embodiment are all 1-ethyl-3-methylimidazolium acetate.

[0043] Example 4 A method for preparing regenerated cellulose multifilament for cord (1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 700 and 1-ethyl-3-methylimidazolium chloride are mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0044] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 12wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 1000, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 95 °C.

[0045] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 40%, the coagulation bath temperature is 15 °C, the stretching ratio is 1.8 times, and the stretching speed is 90 m / min; (4) Multi-level gradient water washing The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 29%, the temperature is 50 °C, and the stretching speed is 90 m / min; The conditions of the second-stage water washing bath are: the composition is an ionic liquid aqueous solution with a mass fraction of 16%, the temperature is 50 °C, and the stretching speed is 90 m / min; The third-stage water washing bath conditions are: composition of 12% by mass ionic liquid aqueous solution, temperature of 50 °C, and stretching speed of 90 m / min; The fourth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 7%, the temperature is 50 °C, and the stretching speed is 90 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 2%, the temperature is 50 °C, and the stretching speed is 90 m / min; (5) Post-processing The filaments were washed with gradient water, then rinsed, oiled and heat-set to obtain regenerated cellulose industrial yarn. The regenerated cellulose industrial yarn had a fineness of 1860 dtex, a breaking strength of 4.9 cN / dtex, a breaking strength CV (%) of 2.0%, an elongation at break of 10.3%, an elongation at break CV (%) of 2.1%, a dry heat shrinkage at 177°C and 0.01 cN / dtex of 0.6%, and a dry heat shrinkage CV (%) of 1.7% at 177°C and 0.01 cN / dtex.

[0046] The ionic liquids in this embodiment are all 1-ethyl-3-methylimidazolium chloride.

[0047] Comparative Example 1 On the basis of Example 1, the coagulation conditions and the washing conditions were changed to prepare the regenerated cellulose fibers. The specific steps are as follows: (1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 700 and 1-butyl-3-methylimidazolium chloride are mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0048] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 10wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 660, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 95 °C.

[0049] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 20%, the coagulation bath temperature is 25 °C, the stretching ratio is 1.5 times, and the stretching speed is 80 m / min; (4) Post-processing The filaments coagulated in a coagulation bath are then rinsed, oiled and heat-set to obtain regenerated cellulose industrial yarns. The regenerated cellulose industrial yarns have a fineness of 1650 dtex, a breaking strength of 5.1 cN / dtex, a breaking strength CV (%) of 4.3%, an elongation at break of 8.2%, an elongation at break CV (%) of 5.2%, a dry heat shrinkage at 177°C and 0.01 cN / dtex of 0.7%, and a dry heat shrinkage CV (%) of 177°C and 0.01 cN / dtex of 3.1%.

[0050] The ionic liquids in this comparative example are all 1-butyl-3-methylimidazolium chloride.

[0051] Comparative Example 2 Based on Example 2, the coagulation conditions and washing conditions were changed to prepare regenerated cellulose fibers. The specific steps are as follows: (1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 800 and 1-allyl-3-methylimidazolium chloride were mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0052] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 10wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 1000, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 90 °C.

[0053] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 20%, the coagulation bath temperature is 25 °C, the stretching ratio is 1.8 times, and the stretching speed is 120 m / min; (4) Post-processing The filaments coagulated in a coagulation bath are then washed, oiled and heat-set to obtain regenerated cellulose industrial yarns. The regenerated cellulose industrial yarns have a fineness of 2000 dtex, a breaking strength of 5.2 cN / dtex, a breaking strength CV (%) of 4.1%, an elongation at break of 7.3%, an elongation at break CV (%) of 4.8%, a dry heat shrinkage at 177°C and 0.01 cN / dtex of 0.7%, and a dry heat shrinkage CV (%) of 177°C and 0.01 cN / dtex of 2.9%.

[0054] The ionic liquids in this comparative example are all 1-allyl-3-methylimidazolium chloride.

[0055] Comparative Example 3 Based on Example 1, the washing conditions were changed to prepare regenerated cellulose fibers. The specific steps were as follows: 1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 700 and 1-butyl-3-methylimidazolium chloride are mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0056] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 10wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 660, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 95 °C.

[0057] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 40%, the coagulation bath temperature is 15 °C, the stretching ratio is 1.5 times, and the stretching speed is 80 m / min; (4) Gradient water washing The tow coagulated in the coagulation bath enters the first-stage water washing bath and the second-stage water washing bath in sequence for gradient water washing; The first-stage water washing bath conditions are: the composition is 25% by mass of ionic liquid aqueous solution, the temperature is 80 °C, and the stretching speed is 80 m / min; The conditions of the second-stage water washing bath are: the composition is an ionic liquid aqueous solution with a mass fraction of 15%, the temperature is 80 °C, and the stretching speed is 80 m / min; (5) Post-processing The filaments were washed with gradient water, then rinsed, oiled and heat-set to obtain regenerated cellulose industrial yarns. The regenerated cellulose industrial yarns had a fineness of 1650 dtex, a breaking strength of 5.1 cN / dtex, a breaking strength CV (%) of 4.6%, an elongation at break of 7.8%, an elongation at break CV (%) of 4.9%, a dry heat shrinkage at 177°C and 0.01 cN / dtex of 0.7%, and a dry heat shrinkage CV (%) of 177°C and 0.01 cN / dtex of 3.6%.

[0058] The ionic liquids in this comparative example are all 1-butyl-3-methylimidazolium chloride.

[0059] Comparative Example 4 Based on Example 1, the washing conditions were changed to prepare regenerated cellulose fibers. The specific steps were as follows: (1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 700 and 1-butyl-3-methylimidazolium chloride are mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0060] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 10wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 660, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 95 °C.

[0061] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 40%, the coagulation bath temperature is 15 °C, the stretching ratio is 1.5 times, and the stretching speed is 80 m / min; (4) Multi-level gradient water washing The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: composition of 30% by mass ionic liquid aqueous solution, temperature of 70 °C, and stretching speed of 80 m / min; The conditions of the second-stage water washing bath are: the composition is 20% by mass of ionic liquid aqueous solution, the temperature is 70 °C, and the stretching speed is 80 m / min; The third-stage water washing bath conditions are: composition of 15% by mass ionic liquid aqueous solution, temperature of 70 °C, and stretching speed of 80 m / min; The fourth-stage water bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 10%, the temperature is 70 °C, and the stretching speed is 80 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 5%, the temperature is 70 °C, and the stretching speed is 80 m / min; (5) Post-processing The filaments were washed with gradient water, and then rinsed, oiled and heat-set to obtain regenerated cellulose industrial yarn. The regenerated cellulose industrial yarn had a fineness of 1650 dtex, a breaking strength of 4.9 cN / dtex, a breaking strength CV (%) of 3.5%, an elongation at break of 8.1%, an elongation at break CV (%) of 3.8%, a dry heat shrinkage at 177 °C and 0.01 cN / dtex of 0.6%, and a dry heat shrinkage CV (%) of 177 °C and 0.01 cN / dtex of 2.7%.

[0062] The ionic liquids in this comparative example are all 1-butyl-3-methylimidazolium chloride.

[0063] Comparative Example 5 Based on Example 1, the washing conditions were changed to prepare regenerated cellulose fibers. The specific steps were as follows: (1) Preparation of spinning solution: Cellulose pulp with a degree of polymerization of 700 and 1-butyl-3-methylimidazolium chloride are mixed, and dehydrated and dissolved at a temperature of 100°C and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning solution.

[0064] The dissolution process is a wet dissolution process; The solid content of cellulose in the spinning solution is 10wt%; (2) Spinning The prepared cellulose spinning stock solution was extruded through a spinneret for spinning; the number of spinneret holes was 660, the spinneret hole diameter was 0.06 mm, and the spinning temperature was 95 °C.

[0065] (3) Solidification After the extruded filaments pass through the air section, they enter the coagulation bath; Air section length 30 mm; The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 40%, the coagulation bath temperature is 15 °C, the stretching ratio is 1.5 times, and the stretching speed is 80 m / min; (4) Multi-stage gradient water washing The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: the composition is 17% by mass of ionic liquid aqueous solution, the temperature is 40 °C, and the stretching speed is 80 m / min; The conditions of the second-stage water washing bath are: the composition is an ionic liquid aqueous solution with a mass fraction of 12%, the temperature is 40 °C, and the stretching speed is 80 m / min; The third-stage water washing bath conditions are: composition of 7% by mass ionic liquid aqueous solution, temperature of 40 °C, and stretching speed of 80 m / min; The fourth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 2%, the temperature is 40 °C, and the stretching speed is 80 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 0%, the temperature is 40 °C, and the stretching speed is 80 m / min; (5) Post-processing The filaments were washed with gradient water, and then rinsed, oiled and heat-set to obtain regenerated cellulose industrial yarn. The regenerated cellulose industrial yarn had a fineness of 1650 dtex, a breaking strength of 4.9 cN / dtex, a breaking strength CV (%) of 3.2%, an elongation at break of 8.7%, an elongation at break CV (%) of 3.5%, a dry heat shrinkage at 177°C and 0.01 cN / dtex of 0.6%, and a dry heat shrinkage CV (%) of 177°C and 0.01 cN / dtex of 2.8%.

[0066] The ionic liquids in this comparative example are all 1-butyl-3-methylimidazolium chloride.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the protection scope of the present invention.

Claims

1. A regenerated cellulose multifilament, characterized in that: The regenerated cellulose multifilament has a fineness of 800-3000 dtex, a breaking strength of 4.5-6 cN / dtex, a breaking strength CV (%) ≤2.5%, a breaking elongation of 8-15%, a breaking elongation CV (%) ≤2.5%, a dry heat shrinkage at 177°C and 0.01 cN / dtex of ≤0.7%, and a dry heat shrinkage CV (%) ≤2.5% at 177°C and 0.01 cN / dtex; the regenerated cellulose multifilament consists of 100-3000 single filaments.

2. The method for preparing a regenerated cellulose multifilament according to claim 1, characterized in that: The steps include: (1) Preparation of spinning solution; (2) Spinning; (3) Coagulation: After the extruded filaments pass through the air section, they enter the coagulation bath. The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 0-60%, the coagulation bath temperature is 0-30 °C, the stretching ratio is 1-5 times, and the stretching speed is 10-200 m / min. (4) Multi-level gradient water washing: The tow coagulated in the coagulation bath enters the first-stage water washing bath, the second-stage water washing bath, the third-stage water washing bath, the fourth-stage water washing bath and the fifth-stage water washing bath in sequence for multi-stage gradient water washing; The first-stage water washing bath conditions are: an ionic liquid aqueous solution with a composition of 10-30% by mass, a temperature of 10-50 °C, and a stretching speed of 10-200 m / min; The conditions of the second-stage water washing bath are: the composition is an ionic liquid aqueous solution with a mass fraction of 10-25%, the temperature is 10-50 °C, and the stretching speed is 10-200 m / min; The third-stage water washing bath conditions are: an ionic liquid aqueous solution with a composition of 5-20% by mass, a temperature of 10-50 °C, and a stretching speed of 10-200 m / min; The fourth-stage water washing bath conditions are: an ionic liquid aqueous solution with a composition of 5-15% by mass, a temperature of 10-50 °C, and a stretching speed of 10-200 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 0-10%, the temperature is 10-50 °C, and the stretching speed is 10-200 m / min; The ionic liquid concentration of each level of water washing bath is determined according to the ionic liquid content in the tow when entering each level of water washing bath; the ionic liquid concentration of each level of water washing bath is 5-10% lower than the ionic liquid concentration in the tow when entering the water washing bath of that level; After post-treatment, regenerated cellulose multifilament is obtained; the regenerated cellulose multifilament consists of 600-2000 single filaments.

3. The method for preparing a regenerated cellulose multifilament according to claim 2, characterized in that: In step (3), the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 30-50%, the coagulation bath temperature is 5-20°C, the stretching ratio is 1-2 times, and the stretching speed is 50-150 m / min.

4. The method for preparing a regenerated cellulose multifilament according to claim 2, characterized in that: In step (4), the first-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 20-30%, the water washing bath temperature is 30-50 ° C, and the stretching speed is 50-150 m / min; The second-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 15-25%, the water washing bath temperature is 30-50 ℃, and the stretching speed is 50-150 m / min; The third-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 10-20%, the water washing bath temperature is 30-50 °C, and the stretching speed is 50-150 m / min; The fourth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 5-10%, the water washing bath temperature is 30-50 °C, and the stretching speed is 50-150 m / min; The fifth-stage water washing bath conditions are: the composition is an ionic liquid aqueous solution with a mass fraction of 0-5%, the water washing bath temperature is 30-50° C., and the stretching speed is 50-150 m / min.

5. The method for preparing a regenerated cellulose multifilament according to claim 2, characterized in that: In step (1), cellulose pulp with a degree of polymerization of 500-1500 and an ionic liquid are mixed, dehydrated and dissolved to prepare a cellulose spinning solution with a concentration of 5-20wt%; the ionic liquid is one or more of 1-butyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium acetate.

6. The method for preparing a regenerated cellulose multifilament according to claim 5, characterized in that: In step (1), the degree of polymerization of the cellulose pulp is 700-1000; and the solid content of cellulose in the spinning solution is 8-15wt%.

7. The method for preparing regenerated cellulose multifilament according to claim 2, characterized in that: In step (2), the prepared cellulose spinning stock solution is extruded through a spinneret for spinning; the number of spinneret holes is 100-3000 holes; the diameter of the spinneret holes is 0.04-0.2 mm; and the spinning temperature is 80-120°C.

8. The method for preparing regenerated cellulose multifilament according to claim 7, characterized in that: In step (2), the number of spinneret holes is 600-2000 holes; the diameter of the spinneret holes is 0.05-0.08 mm; and the spinning temperature is 95-110 °C.

9. The method for preparing a regenerated cellulose multifilament according to claim 2, characterized in that: In step (5), the filaments are washed with multi-stage gradient water, and then rinsed, oiled, and heat-set to obtain regenerated cellulose multifilaments.

10. A cord made from the regenerated cellulose multifilament according to claim 1.

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