A regenerated cellulose multifilament for a cord and a method for producing the same

Abstract

The present application belongs to the field of fiber preparation, and particularly relates to a kind of regenerated cellulose multifilament for cord and a preparation method thereof.The regenerated cellulose multifilament prepared by the present application is extruded from a spinneret by cellulose solution, enters a coagulation bath through a gas gap section, then is washed by multiple-stage gradient water, and then is subjected to leaching, oiling and heat setting to obtain the regenerated cellulose multifilament with low breaking strength and breaking elongation coefficient of variation (CV (%)). The present application reduces the breaking strength and breaking elongation coefficient of variation (CV (%)) of the regenerated cellulose multifilament, and meets the performance requirements of the regenerated cellulose multifilament for cord.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fiber preparation, and particularly relates to a regenerated cellulose multifilament for cord and a preparation method thereof. BACKGROUND

[0002] The regenerated cellulose fiber has a unique position in the field of tire cord due to its excellent dimensional stability, especially the good dimensional stability under high temperature conditions, and good adhesion to rubber, and is mainly applied to the tire radial of high-speed driving. At present, the regenerated cellulose fiber applied to the tire cord is mainly viscose strong silk, but the existing production capacity of the viscose strong silk cannot meet the market demand, and the increase of the production capacity is limited due to the great pollution in the production process of the viscose strong silk. The regenerated cellulose multifilament prepared by the ionic liquid solvent method is dissolved in a direct way, and the dissolution and regeneration are physical processes. The solvent can be recycled and reused, which opens up the road for the clean preparation of the 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 has the potential to be applied to the tire cord.

[0003] At present, the regenerated cellulose fiber product prepared by the ionic liquid solvent method has been widely applied to the civil field, such as clothing, home textiles, medical treatment and the like. However, as the industrial field of tire cord and the like, the performance requirements of the regenerated cellulose multifilament are obviously different from those in the civil field. In addition to the high strength and modulus, the performance indicators should also have high uniformity and stability, so as to ensure the stable performance of the regenerated cellulose multifilament as the cord material. The uniformity and stability of the performance indicators can be represented by the coefficient of variation (CV (%)).

[0004] The patent CN101578401B proposes to adjust the coagulation coefficient by adjusting the air section and the coagulation bath temperature, so as to reduce the coefficient of variation of the cross-sectional diameter of each filament in the regenerated cellulose multifilament. The method disclosed in the patent reduces the coefficient of variation of the cross-sectional diameter of each filament in the regenerated cellulose multifilament, and improves the uniformity of the cross-sectional diameter of each filament in the multifilament. However, the uniformity of the performance indicators of the regenerated cellulose multifilament, such as the breaking strength, elongation at break and modulus, is not improved.

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

[0006] Patent CN117535804A discloses a preparation method and equipment of regenerated cellulose industrial silk, which adopts gradient coagulation means, increases the residual solvent in the silk, and makes the silk shrink in high temperature coagulation conditions to improve the breaking elongation rate of the product; at the same time, the structural difference of single silk along the radial direction is reduced to ensure the performance of the product. However, the use of high temperature coagulation conditions, although provides conditions for the movement of cellulose molecular segments, but also accelerates the rate of double diffusion, which cannot ensure the stability of the forming conditions of the whole silk bundle, and thus cannot ensure the stable performance of the regenerated cellulose multifilament.

[0007] Although many patents disclose the preparation of regenerated cellulose fibers by ion liquid solvent method, in the ion liquid solvent method for spinning regenerated cellulose fibers, the concentration of the spinning solution, the length of the air section, the coagulation bath conditions, the washing conditions, the spinning speed and the drawing ratio all have an influence on the performance of the regenerated cellulose fibers, and the performance of the regenerated cellulose fibers obtained under different spinning process conditions also has differences. For the regenerated cellulose multifilament for cord, in addition to the requirements of certain breaking strength, breaking elongation and other requirements, the uniform stability of various performance indicators, i.e. low coefficient of variation (CV (%)) is also a very important index, which determines the application performance and use stability of the cord.

[0008] In summary, the existing technology for improving the performance of regenerated cellulose multifilament for application in cord has the following problems: the uniformity of the cross-sectional diameter of each filament in the multifilament is improved, but the uniformity of various performance indicators of the regenerated cellulose multifilament, such as breaking strength, breaking elongation and modulus, is not improved. SUMMARY

[0009] The main purpose of the present application is to provide a regenerated cellulose multifilament for cord and a preparation method thereof, which reduces the coefficient of variation (CV (%)) of the breaking strength and breaking elongation of the regenerated cellulose multifilament, to meet the performance requirements of the cord.

[0010] To solve the problems of the prior art, the present application adopts a new spinning technology route, adopts a mild coagulation bath condition and a multi-stage gradient washing technology route, to prepare a regenerated cellulose multifilament, to achieve the following purposes: reducing the coefficient of variation (CV (%)) of the breaking strength and breaking elongation of the regenerated cellulose multifilament, and improving the uniformity of the breaking strength and breaking elongation of each filament of the regenerated cellulose multifilament.

[0011] To achieve the above object, the first aspect of the present application adopts the following technical solution: a regenerated cellulose multifilament, the fineness of which is 800-3000 dtex, the breaking strength of which is 4.5-6 cN / dtex, the breaking strength CV of which is ≤2.5 %, the breaking elongation of which is 8-15 %, the breaking elongation CV of which is ≤2.5 %, the dry heat shrinkage under the condition of 177 ℃ and 0.01 cN / dtex of which is ≤0.7 %, and the dry heat shrinkage CV under the condition of 177 ℃ and 0.01 cN / dtex of which is ≤2.5 %; the regenerated cellulose multifilament is composed of 100-3000 filaments.

[0012] The second aspect of the present application discloses a preparation method of the aforementioned regenerated cellulose multifilament, comprising the following steps:

[0013] (1) preparation of a spinning dope;

[0014] (2) spinning;

[0015] (3) coagulation: the extruded yarn is led into a coagulation bath after passing through an air section; the coagulation bath conditions are as follows: the coagulation bath is an aqueous ionic liquid solution with a mass fraction of 30-60 %, the coagulation bath temperature is 0-30 ℃, the draw ratio is 1-5 times, and the drawing speed is 10-200 m / min;

[0016] (4) multi-stage gradient washing:

[0017] the yarn bundle coagulated in the coagulation bath is sequentially led into a first-stage washing bath, a second-stage washing bath, a third-stage washing bath, a fourth-stage washing bath and a fifth-stage washing bath for multi-stage gradient washing;

[0018] the first-stage washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 10-30 %, the temperature is 10-50 ℃, and the drawing speed is 10-200 m / min;

[0019] the second-stage washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 10-25 %, the temperature is 10-50 ℃, and the drawing speed is 10-200 m / min;

[0020] the third-stage washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 5-20 %, the temperature is 10-50 ℃, and the drawing speed is 10-200 m / min;

[0021] the fourth-stage washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 5-15 %, the temperature is 10-50 ℃, and the drawing speed is 10-200 m / min;

[0022] The fifth washing bath has a composition of 0-10% ionic liquid aqueous solution, a temperature of 10-50°C, and a stretching speed of 10-200 m / min;

[0023] The concentration of the ionic liquid in each washing bath is determined according to the content of the ionic liquid in the filament entering the washing bath, and the concentration of the ionic liquid in each washing bath (i.e. the mass content or mass fraction) is 5-10% lower than the concentration of the ionic liquid in the filament entering the washing bath (i.e. the mass content or mass fraction);

[0024] (5) post-treatment to obtain regenerated cellulose multifilament; the regenerated cellulose multifilament is composed of 600-2000 single filaments.

[0025] In a preferred embodiment, 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, and the stretching ratio is 1-2 times, and the stretching speed is 50-150 m / min.

[0026] In a preferred embodiment, in step (4), the first washing bath has a composition of 20-30% ionic liquid aqueous solution, a temperature of 30-50°C, and a stretching speed of 50-150 m / min;

[0027] The second washing bath has a composition of 15-25% ionic liquid aqueous solution, a temperature of 30-50°C, and a stretching speed of 50-150 m / min;

[0028] The third washing bath has a composition of 10-20% ionic liquid aqueous solution, a temperature of 30-50°C, and a stretching speed of 50-150 m / min;

[0029] The fourth washing bath has a composition of 5-10% ionic liquid aqueous solution, a temperature of 30-50°C, and a stretching speed of 50-150 m / min;

[0030] The fifth washing bath has a composition of 0-5% ionic liquid aqueous solution, a temperature of 30-50°C, and a stretching speed of 50-150 m / min.

[0031] In step (1), cellulose pulp with a degree of polymerization of 500-1500 is mixed with an ionic liquid to be dehydrated and dissolved to prepare a cellulose spinning dope 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.

[0032] Preferably, in step (1), the degree of polymerization of the cellulose pulp is 700-1000; the solid content of the cellulose in the spinning dope is 8-15 wt%.

[0033] In step (2), the prepared cellulose spinning dope is extruded through a spinneret cap for spinning; the number of spinneret holes is 100-3000 holes; the spinneret hole diameter is 0.04-0.2 mm; the spinning temperature is 80-120 ℃.

[0034] Further, in step (2), the number of spinneret holes is 600-2000 holes; the spinneret hole diameter is 0.05-0.08 mm; the spinning temperature is 95-110 ℃.

[0035] In step (5), the yarn after multi-stage gradient washing is obtained by rinsing, oiling and heat setting to obtain regenerated cellulose multifilament.

[0036] The third aspect of the present application is to provide a cord made of the aforementioned regenerated cellulose multifilament.

[0037] The regenerated cellulose multifilament prepared by the present application is prepared by extruding cellulose solution from a spinneret hole, passing through a gas gap section into a coagulation bath, then passing through a multi-stage gradient washing, and then rinsing, 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 prepared by a dry-jet wet spinning process comprising a coagulation bath with a mild forming condition and a five-stage gradient washing bath. During the coagulation and washing process, the yarn bundle 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 several hundred to several thousand single filaments, so during the forming process, the yarn bundle core (green part) and the yarn bundle periphery (blue part) have different diffusion conditions, which leads to the formation of a yarn bundle with a core-sheath structure. Figure 1 The core-sheath structure of the yarn bundle leads to the formation of a yarn bundle with a core-sheath structure. Figure 1The forming condition of the middle blue part is particularly important to the uniformity of the whole bundle. The filaments of the outer circle of the bundle are more likely to contact with the coagulation bath and the washing bath, and the double diffusion process occurs first. If the difference between the solvent concentration of the bundle and the concentration of each bath is too large, the outer circle of the bundle will be coagulated quickly, and the solvent concentration of the bath at the outer circle of the bundle will rise rapidly, which will increase the local ionic liquid concentration of the core of the bundle, and the coagulation speed of the outer circle of the bundle will be faster than that of the core, which will reduce the uniformity of the final fiber. Compared with the existing process, the application (1) uses a high-concentration low-temperature coagulation bath, which reduces the double diffusion rate of the bundle in the coagulation bath, weakens the effect of the rapid rise of the local bath concentration due to the double diffusion of the outer circle of the bundle, reduces the difference in the local ionic liquid concentration between the outer circle and the core of the bundle during coagulation, and improves the uniformity of the whole bundle; (2) adopts a multi-stage gradient washing technology, and according to the ionic liquid content in the bundle entering each stage of the washing bath, the appropriate ionic liquid concentration is set in each stage of the washing bath, and the ionic liquid concentration in each stage of the washing bath is 5-10% lower than the ionic liquid concentration in the bundle entering each stage of the washing bath, so as to delay the double diffusion process of the bundle in each stage of the washing bath, reduce the difference in the ionic liquid concentration between the outer circle and the core of the bundle, and achieve the purpose of removing the ionic liquid in the bundle while ensuring the uniform coagulation of the fiber.

[0038] Compared with the prior art:

[0039] (1) The regenerated cellulose multifilament prepared by the application 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 rate under the condition of 177 ℃ and 0.01 cN / dtex≤0.7%, and a dry heat shrinkage rate CV under the condition of 177 ℃ and 0.01 cN / dtex≤2.5%.

[0040] (2) The regenerated cellulose industrial yarn prepared by the application can meet the application requirements of the cord. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 It is a cross-sectional view of the coagulated bundle. DETAILED DESCRIPTION

[0042] The application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or modifications to the application after reading the content taught by the application, and these equivalent forms also fall within the scope defined by the claims attached hereto.

[0043] The following is a specific scheme of the technical route of the application:

[0044] (1) Preparation of the spinning dope:

[0045] The cellulose pulp with a degree of polymerization of 500-1500 is mixed with an ionic liquid to prepare a cellulose spinning dope with a concentration of 5-20 wt%.

[0046] The dissolving process is a wet dissolving process;

[0047] The degree of polymerization of the cellulose pulp is preferably 700-1000;

[0048] 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, etc.

[0049] The solid content of the cellulose in the spinning dope is preferably 8-15 wt%.

[0050] (2) Spinning

[0051] The prepared cellulose spinning dope is extruded through a spinneret cap for spinning; the number of spinneret holes is 100-3000, preferably 600-2000; the diameter of the spinneret holes is 0.04-0.2 mm, preferably 0.05-0.08 mm; the spinning temperature is 80-120 ℃, preferably 95-110 ℃.

[0052] (3) Coagulation

[0053] The extruded filaments enter a coagulation bath after passing through an air section;

[0054] The length of the air section is 5-500 mm, preferably 20-50 mm;

[0055] The coagulation bath conditions are as follows: the coagulation bath is an ionic liquid aqueous solution with a mass fraction of 30-60%, the coagulation bath temperature is 0-30 ℃, and the draw ratio is 1-5, and the draw 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 ℃, the draw ratio is 1-2, and the draw speed is 50-150 m / min;

[0056] (4) Multi-stage gradient water washing

[0057] The filaments coagulated in the coagulation bath enter a first-stage water washing bath, a second-stage water washing bath, a third-stage water washing bath, a fourth-stage water washing bath, and a fifth-stage water washing bath in sequence for multi-stage gradient water washing;

[0058] The first stage water washing bath conditions are: 10-30% ionic liquid aqueous solution by mass fraction, temperature 10-50°C, drawing speed 10-200 m / min; preferably: water washing bath is 20-30% ionic liquid aqueous solution by mass fraction, water washing bath temperature is 30-50°C, drawing speed is 50-150 m / min;

[0059] The second stage water washing bath conditions are: 10-25% ionic liquid aqueous solution by mass fraction, temperature 10-50°C, drawing speed 10-200 m / min; preferably: water washing bath is 15-25% ionic liquid aqueous solution by mass fraction, water washing bath temperature is 30-50°C, drawing speed is 50-150 m / min;

[0060] The third stage water washing bath conditions are: 5-20% ionic liquid aqueous solution by mass fraction, temperature 10-50°C, drawing speed 10-200 m / min; preferably: water washing bath is 10-20% ionic liquid aqueous solution by mass fraction, water washing bath temperature is 30-50°C, drawing speed is 50-150 m / min;

[0061] The fourth stage water washing bath conditions are: 5-15% ionic liquid aqueous solution by mass fraction, temperature 10-50°C, drawing speed 10-200 m / min; preferably: water washing bath is 5-10% ionic liquid aqueous solution by mass fraction, water washing bath temperature is 30-50°C, drawing speed is 50-150 m / min;

[0062] The fifth stage water washing bath conditions are: 0-10% ionic liquid aqueous solution by mass fraction, temperature 10-50°C, drawing speed 10-200 m / min; preferably: water washing bath is 0-5% ionic liquid aqueous solution by mass fraction, water washing bath temperature is 30-50°C, drawing speed is 50-150 m / min;

[0063] (5) Post-treatment

[0064] The regenerated cellulose multifilament is obtained after the yarn is washed by a multi-stage water washing gradient, and then is washed, oiled and heat set. The regenerated cellulose industrial yarn 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 under the condition of 177 ℃ and 0.01 cN / dtex≤0.7 %, and a dry heat shrinkage CV under the condition of 177 ℃ and 0.01 cN / dtex≤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 %, the dry heat shrinkage under the condition of 177 ℃ and 0.01 cN / dtex≤0.6 %, and the dry heat shrinkage CV under the condition of 177 ℃ and 0.01 cN / dtex≤2.5 %.

[0065] Example 1: Preparation method of regenerated cellulose multifilament for a cord

[0066] (1) Preparation of a spinning dope

[0067] The cellulose pulp with a degree of polymerization of 700 and 1-butyl-3-methylimidazolium chloride are mixed, and are subjected to dewatering and dissolution under the condition of a temperature of 100 ℃ and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning dope.

[0068] The dissolution process is a wet dissolution process;

[0069] The solid content of the cellulose in the spinning dope is 10 wt%;

[0070] (2) Spinning

[0071] The prepared cellulose spinning dope is extruded through a spinneret cap to perform spinning; the number of spinneret holes is 660, the diameter of the spinneret holes is 0.06 mm, and the spinning temperature is 95 ℃.

[0072] (3) Coagulation

[0073] The extruded yarn is subjected to an air section and then enters a coagulation bath;

[0074] The length of the air section is 30 mm;

[0075] The coagulation bath has a mass fraction of 40% ionic liquid aqueous solution, a coagulation bath temperature of 15 ℃, a draw ratio of 1.5 times, and a drawing speed of 80 m / min;

[0076] (4) Multi-stage gradient water washing

[0077] The filament bundle coagulated by 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;

[0078] The first-stage water washing bath has a composition of 30% by mass of the ionic liquid aqueous solution, a temperature of 40℃ and a drawing speed of 80 m / min;

[0079] The second-stage water washing bath has a composition of 20% by mass of the ionic liquid aqueous solution, a temperature of 40℃ and a drawing speed of 80 m / min;

[0080] The third-stage water washing bath has a composition of 15% by mass of the ionic liquid aqueous solution, a temperature of 40℃ and a drawing speed of 80 m / min;

[0081] The fourth-stage water washing bath has a composition of 10% by mass of the ionic liquid aqueous solution, a temperature of 40℃ and a drawing speed of 80 m / min;

[0082] The fifth-stage water washing bath has a composition of 5% by mass of the ionic liquid aqueous solution, a temperature of 40℃ and a drawing speed of 80 m / min;

[0083] (5) Post-treatment

[0084] The filament bundle subjected to the gradient water washing is subjected to rinsing, oiling and heat setting to obtain regenerated cellulose industrial yarn, which has a fineness of 1650 dtex, a breaking strength of 4.8 cN / dtex, a breaking strength CV of 2.3%, a breaking elongation of 9%, a breaking elongation CV of 2.1%, a dry heat shrinkage at 177℃ and 0.01 cN / dtex of 0.5% and a dry heat shrinkage CV at 177℃ and 0.01 cN / dtex of 1.7%.

[0085] The ionic liquid in the embodiment is 1-butyl-3-methylimidazolium chloride.

[0086] Example 2: Preparation method of regenerated cellulose multifilament for cord

[0087] (1) Preparation of spinning dope:

[0088] The cellulose pulp with a degree of polymerization of 800 is mixed with 1-allyl-3-methylimidazolium chloride, and is subjected to dewatering and dissolution under the conditions of a temperature of 100℃ and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning dope.

[0089] The dissolution process is a wet dissolution process;

[0090] The solid content of cellulose in the spinning dope is 10 wt%;

[0091] (2) Spinning

[0092] The prepared cellulose spinning dope is extruded through a spinneret cap for spinning; the number of spinneret holes is 1000, the diameter of the spinneret holes is 0.06 mm, and the spinning temperature is 90°C.

[0093] (3) Coagulation

[0094] The extruded filaments enter a coagulation bath after passing through an air section;

[0095] The length of the air section is 30 mm;

[0096] The coagulation bath conditions are: the coagulation bath is an aqueous ionic liquid solution with a mass fraction of 50%, the coagulation bath temperature is 20°C, the draw ratio is 1.8 times, and the draw speed is 120 m / min;

[0097] (4) Multi-stage gradient washing

[0098] The filaments coagulated in the coagulation bath sequentially enter a first-stage washing bath, a second-stage washing bath, a third-stage washing bath, a fourth-stage washing bath, and a fifth-stage washing bath for multi-stage gradient washing;

[0099] The first-stage washing bath conditions are: the composition is an aqueous ionic liquid solution with a mass fraction of 30%, the temperature is 50°C, and the draw speed is 120 m / min;

[0100] The second-stage washing bath conditions are: the composition is an aqueous ionic liquid solution with a mass fraction of 23%, the temperature is 50°C, and the draw speed is 120 m / min;

[0101] The third-stage washing bath conditions are: the composition is an aqueous ionic liquid solution with a mass fraction of 16%, the temperature is 50°C, and the draw speed is 120 m / min;

[0102] The fourth-stage washing bath conditions are: the composition is an aqueous ionic liquid solution with a mass fraction of 12%, the temperature is 50°C, and the draw speed is 120 m / min;

[0103] The fifth-stage washing bath conditions are: the composition is an aqueous ionic liquid solution with a mass fraction of 5%, the temperature is 50°C, and the draw speed is 120 m / min;

[0104] (5) Post-treatment

[0105] The yarns after gradient water washing, then through rinsing, oiling, heat setting, the regenerated cellulose industrial yarn is obtained, the regenerated cellulose industrial yarn has a fineness of 2000 dtex, a breaking strength of 4.9 cN / dtex, a breaking strength CV of 2.2 %, a breaking elongation of 8.3 %, a breaking elongation CV of 2.1 %, a dry heat shrinkage at 177 ℃ and 0.01 cN / dtex of 0.6 %, and a dry heat shrinkage CV at 177 ℃ and 0.01 cN / dtex of 1.8 %.

[0106] The ionic liquid in the embodiment is 1-allyl-3-methylimidazole chloride.

[0107] Example 3: Preparation method of regenerated cellulose multifilament for cord

[0108] (1) Preparation of spinning dope:

[0109] The cellulose pulp with a degree of polymerization of 800 is mixed with 1-ethyl-3-methylimidazole acetate, and is subjected to dewatering and dissolution under the conditions of a temperature of 100 ℃ and a vacuum degree of 500 Pa for 90 min, to obtain a cellulose spinning dope.

[0110] The dissolving process is a wet dissolving process;

[0111] The solid content of the cellulose in the spinning dope is 13 wt%;

[0112] (2) Spinning

[0113] The prepared cellulose spinning dope is extruded through a spinneret cap for spinning; the number of spinneret holes is 1000, the diameter of the spinneret holes is 0.06 mm, and the spinning temperature is 85 ℃.

[0114] (3) Coagulation

[0115] The extruded yarns enter a coagulation bath after passing through an air section;

[0116] The length of the air section is 30 mm;

[0117] 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 ℃, the draw ratio is 1.7 times, and the draw speed is 100 m / min;

[0118] (4) Multi-stage gradient water washing

[0119] The yarns coagulated in the coagulation bath enter a first-stage water washing bath, a second-stage water washing bath, a third-stage water washing bath, a fourth-stage water washing bath, and a fifth-stage water washing bath in sequence for multi-stage gradient water washing;

[0120] The first-stage water washing bath condition is: the ionic liquid aqueous solution with a mass fraction of 28%, a temperature of 50 ℃, and a drawing speed of 100 m / min;

[0121] The second-stage water washing bath condition is: the ionic liquid aqueous solution with a mass fraction of 17%, a temperature of 50 ℃, and a drawing speed of 100 m / min;

[0122] The third-stage water washing bath condition is: the ionic liquid aqueous solution with a mass fraction of 13%, a temperature of 50 ℃, and a drawing speed of 100 m / min;

[0123] The fourth-stage water washing bath condition is: the ionic liquid aqueous solution with a mass fraction of 8%, a temperature of 50 ℃, and a drawing speed of 100 m / min;

[0124] The fifth-stage water washing bath condition is: the ionic liquid aqueous solution with a mass fraction of 3%, a temperature of 50 ℃, and a drawing speed of 100 m / min;

[0125] (5) Post-treatment

[0126] After the gradient water washing, the yarn is subjected to rinsing, oiling, and heat setting to obtain the regenerated cellulose industrial yarn, which has a fineness of 1800 dtex, a breaking strength of 4.7 cN / dtex, a breaking strength CV of 2.1%, a breaking elongation of 9.7%, a breaking elongation CV of 2.3%, a dry heat shrinkage at 177 ℃ and 0.01 cN / dtex of 0.5%, and a dry heat shrinkage CV at 177 ℃ and 0.01 cN / dtex of 1.9%.

[0127] The ionic liquid in the embodiment is 1-ethyl-3-methylimidazole acetate.

[0128] Example 4: Preparation method of regenerated cellulose multifilament for cord

[0129] (1) Preparation of the spinning dope:

[0130] The cellulose pulp with a degree of polymerization of 700 is mixed with 1-ethyl-3-methylimidazole chloride, and is subjected to dewatering and dissolution under the conditions of a temperature of 100 ℃ and a vacuum degree of 500 Pa for 90 min to obtain the cellulose spinning dope.

[0131] The dissolving process is a wet dissolving process;

[0132] The solid content of the cellulose in the spinning dope is 12 wt%;

[0133] (2) Spinning

[0134] The prepared cellulose spinning dope is extruded through a spinneret cap for spinning; the number of spinneret holes is 1000, the spinneret hole diameter is 0.06 mm, and the spinning temperature is 95 ℃.

[0135] (3) coagulation

[0136] The extruded filaments enter a coagulation bath after passing through an air section;

[0137] The air section has a length of 30 mm;

[0138] The coagulation bath conditions are as follows: the coagulation bath is an aqueous ionic liquid solution with a mass fraction of 40%, the coagulation bath temperature is 15 ℃, the draw ratio is 1.8 times, and the drawing speed is 90 m / min;

[0139] (4) multi-stage gradient water washing

[0140] The filaments coagulated in the coagulation bath enter a first-stage water washing bath, a second-stage water washing bath, a third-stage water washing bath, a fourth-stage water washing bath, and a fifth-stage water washing bath in sequence for multi-stage gradient water washing;

[0141] The first-stage water washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 29%, the temperature is 50 ℃, and the drawing speed is 90 m / min;

[0142] The second-stage water washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 16%, the temperature is 50 ℃, and the drawing speed is 90 m / min;

[0143] The third-stage water washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 12%, the temperature is 50 ℃, and the drawing speed is 90 m / min;

[0144] The fourth-stage water washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 7%, the temperature is 50 ℃, and the drawing speed is 90 m / min;

[0145] The fifth-stage water washing bath conditions are as follows: the composition is an aqueous ionic liquid solution with a mass fraction of 2%, the temperature is 50 ℃, and the drawing speed is 90 m / min;

[0146] (5) post-treatment

[0147] The yarns after gradient water washing, then through rinsing, oiling, heat setting, the regenerated cellulose industrial yarn is obtained, the regenerated cellulose industrial yarn has a fineness of 1860 dtex, a breaking strength of 4.9 cN / dtex, a breaking strength CV of 2.0 %, a breaking elongation of 10.3 %, a breaking elongation CV of 2.1 %, a dry heat shrinkage at 177 ℃ and 0.01 cN / dtex of 0.6 %, and a dry heat shrinkage CV at 177 ℃ and 0.01 cN / dtex of 1.7 %.

[0148] The ionic liquid in the embodiment is 1-ethyl-3-methylimidazolium chloride.

[0149] Comparative Example 1

[0150] On the basis of Example 1, the coagulation conditions and water washing conditions are changed to prepare the regenerated cellulose fiber, and the specific steps are as follows:

[0151] (1) Preparation of the spinning dope:

[0152] The cellulose pulp with a degree of polymerization of 700 and 1-butyl-3-methylimidazolium chloride are mixed, and under the conditions of a temperature of 100 ℃ and a vacuum degree of 500 Pa, the cellulose spinning dope is obtained by dehydrating and dissolving for 90 min.

[0153] The dissolving process is a wet dissolving process;

[0154] The solid content of the cellulose in the spinning dope is 10 wt%;

[0155] (2) Spinning

[0156] The prepared cellulose spinning dope is extruded through the spinneret cap for spinning; the number of spinneret holes is 660, the diameter of the spinneret hole is 0.06 mm, and the spinning temperature is 95 ℃.

[0157] (3) Coagulation

[0158] The extruded yarns pass through the air section and then enter the coagulation bath;

[0159] The length of the air section is 30 mm;

[0160] 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 ℃, the draw ratio is 1.5 times, and the drawing speed is 80 m / min;

[0161] (4) Post-treatment

[0162] The yarns solidified in the coagulation bath are obtained into regenerated cellulose industrial yarns after rinsing, oiling and heat setting. The regenerated cellulose industrial yarns obtained have a fineness of 1650 dtex, a breaking strength of 5.1 cN / dtex, a breaking strength CV of 4.3%, a breaking elongation of 8.2%, a breaking elongation CV of 5.2%, a dry heat shrinkage at 177 ℃ and 0.01 cN / dtex of 0.7%, and a dry heat shrinkage CV at 177 ℃ and 0.01 cN / dtex of 3.1%.

[0163] The ionic liquid in the present comparative example is 1-butyl-3-methylimidazolium chloride.

[0164] Comparative Example 2

[0165] On the basis of Example 2, the coagulation conditions and the rinsing conditions are changed to prepare regenerated cellulose fibers, and the specific steps are as follows:

[0166] (1) Preparation of the spinning dope:

[0167] The cellulose pulp with a degree of polymerization of 800 is mixed with 1-allyl-3-methylimidazolium chloride, and is subjected to dewatering and dissolution under the conditions of a temperature of 100 ℃ and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning dope.

[0168] The dissolution process is a wet dissolution process;

[0169] The solid content of the cellulose in the spinning dope is 10 wt%;

[0170] (2) Spinning

[0171] The prepared cellulose spinning dope is extruded through a spinneret cap to perform spinning; the number of spinneret holes is 1000, the diameter of the spinneret holes is 0.06 mm, and the spinning temperature is 90 ℃.

[0172] (3) Coagulation

[0173] The extruded yarns enter a coagulation bath after passing through an air section;

[0174] The length of the air section is 30 mm;

[0175] 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 ℃, the draw ratio is 1.8 times, and the drawing speed is 120 m / min;

[0176] (4) Post-treatment

[0177] The yarns solidified in the coagulation bath are then subjected to rinsing, oiling and heat setting to obtain regenerated cellulose industrial yarns, the regenerated cellulose industrial yarns obtained 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 ℃ and 0.01 cN / dtex of 0.7 %, and a dry heat shrinkage at 177 ℃ and 0.01 cN / dtex CV of 2.9 %.

[0178] The ionic liquid in the present comparative example is 1-allyl-3-methylimidazolium chloride.

[0179] Comparative Example 3

[0180] On the basis of Example 1, the water washing conditions were changed to prepare regenerated cellulose fibers, and the specific steps were as follows:

[0181] 1) Preparation of the spinning dope:

[0182] The cellulose pulp with a degree of polymerization of 700 was mixed with 1-butyl-3-methylimidazolium chloride, and was subjected to dewatering and dissolution under the conditions of a temperature of 100 ℃ and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning dope.

[0183] The dissolution process is a wet dissolution process;

[0184] The solid content of the cellulose in the spinning dope is 10 wt%;

[0185] (2) Spinning

[0186] The prepared cellulose spinning dope was extruded through a spinneret cap to perform spinning; the number of spinneret holes was 660, the diameter of the spinneret holes was 0.06 mm, and the spinning temperature was 95 ℃.

[0187] (3) Coagulation

[0188] The extruded yarns passed through an air section and then entered a coagulation bath;

[0189] The length of the air section was 30 mm;

[0190] The coagulation bath conditions were as follows: the coagulation bath was an aqueous ionic liquid solution with a mass fraction of 40%, the coagulation bath temperature was 15 ℃, the draw ratio was 1.5 times, and the draw speed was 80 m / min;

[0191] (4) Gradient water washing

[0192] The yarns solidified in the coagulation bath entered a first-stage water washing bath and a second-stage water washing bath in sequence to perform gradient water washing;

[0193] The first-stage water washing bath condition is: the composition is an aqueous solution of ionic liquid with a mass fraction of 25%, the temperature is 80 ℃, and the drawing speed is 80 m / min.

[0194] The second-stage water washing bath condition is: the composition is an aqueous solution of ionic liquid with a mass fraction of 15%, the temperature is 80 ℃, and the drawing speed is 80 m / min.

[0195] (5) Post-treatment

[0196] The yarns subjected to gradient water washing are then subjected to rinsing, oiling and heat setting to obtain regenerated cellulose industrial yarns. The regenerated cellulose industrial yarns obtained have a fineness of 1650 dtex, a breaking strength of 5.1 cN / dtex, a breaking strength CV of 4.6%, a breaking elongation of 7.8%, a breaking elongation CV of 4.9%, a dry heat shrinkage at 177 ℃ and 0.01 cN / dtex of 0.7%, and a dry heat shrinkage CV at 177 ℃ and 0.01 cN / dtex of 3.6%.

[0197] The ionic liquid in the present comparative example is 1-butyl-3-methylimidazolium chloride.

[0198] Comparative Example 4

[0199] On the basis of Example 1, the water washing condition is changed to prepare regenerated cellulose fibers, and the specific steps are as follows:

[0200] (1) Preparation of the spinning dope:

[0201] The cellulose pulp with a degree of polymerization of 700 is mixed with 1-butyl-3-methylimidazolium chloride, and is subjected to dewatering and dissolution under the conditions of a temperature of 100 ℃ and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning dope.

[0202] The dissolution process is a wet dissolution process;

[0203] The solid content of the cellulose in the spinning dope is 10 wt%;

[0204] (2) Spinning

[0205] The prepared cellulose spinning dope is extruded through a spinneret cap to perform spinning; the number of spinneret holes is 660, the diameter of the spinneret holes is 0.06 mm, and the spinning temperature is 95 ℃.

[0206] (3) Coagulation

[0207] The extruded yarns enter a coagulation bath after passing through an air section;

[0208] The length of the air section is 30 mm;

[0209] The coagulation bath is an aqueous solution of ionic liquid with a mass fraction of 40%, the coagulation bath temperature is 15 ℃, the stretching ratio is 1.5 times, and the stretching speed is 80 m / min.

[0210] (4) Multi-stage gradient water washing

[0211] The yarns coagulated in the coagulation bath are sequentially subjected to multi-stage gradient water washing in 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.

[0212] The first-stage water washing bath has a composition of an aqueous solution of ionic liquid with a mass fraction of 30%, a temperature of 70 ℃, and a stretching speed of 80 m / min.

[0213] The second-stage water washing bath has a composition of an aqueous solution of ionic liquid with a mass fraction of 20%, a temperature of 70 ℃, and a stretching speed of 80 m / min.

[0214] The third-stage water washing bath has a composition of an aqueous solution of ionic liquid with a mass fraction of 15%, a temperature of 70 ℃, and a stretching speed of 80 m / min.

[0215] The fourth-stage water washing bath has a composition of an aqueous solution of ionic liquid with a mass fraction of 10%, a temperature of 70 ℃, and a stretching speed of 80 m / min.

[0216] The fifth-stage water washing bath has a composition of an aqueous solution of ionic liquid with a mass fraction of 5%, a temperature of 70 ℃, and a stretching speed of 80 m / min.

[0217] (5) Post-treatment

[0218] The yarns subjected to gradient water washing are subjected to rinsing, oiling, and heat setting to obtain regenerated cellulose industrial yarns. The regenerated cellulose industrial yarns have a fineness of 1650 dtex, a breaking strength of 4.9 cN / dtex, a breaking strength CV of 3.5%, a breaking elongation of 8.1%, a breaking elongation CV of 3.8%, a dry heat shrinkage at 177 ℃ and 0.01 cN / dtex of 0.6%, and a dry heat shrinkage CV at 177 ℃ and 0.01 cN / dtex of 2.7%.

[0219] The ionic liquid in the comparative example is 1-butyl-3-methylimidazolium chloride.

[0220] Comparative Example 5

[0221] On the basis of Example 1, the water washing conditions are changed to prepare regenerated cellulose fibers, and the specific steps are as follows:

[0222] (1) Preparation of the spinning dope:

[0223] Cellulose pulp with a degree of polymerization of 700 and 1-butyl-3-methylimidazolium chloride were mixed, and were dehydrated and dissolved under the conditions of a temperature of 100 ℃ and a vacuum degree of 500 Pa for 90 min to obtain a cellulose spinning dope.

[0224] The dissolving process is a wet dissolving process;

[0225] The solid content of the cellulose in the spinning dope is 10 wt%;

[0226] (2) Spinning

[0227] The prepared cellulose spinning dope was extruded through a spinneret cap for spinning; the number of spinneret holes was 660, the diameter of the spinneret holes was 0.06 mm, and the spinning temperature was 95 ℃.

[0228] (3) Coagulation

[0229] The extruded filaments passed through an air section and then entered a coagulation bath;

[0230] The length of the air section was 30 mm;

[0231] The coagulation bath conditions were as follows: the coagulation bath was an aqueous ionic liquid solution with a mass fraction of 40%, the coagulation bath temperature was 15 ℃, the draw ratio was 1.5 times, and the draw speed was 80 m / min;

[0232] (4) Multi-stage gradient washing

[0233] The filaments coagulated in the coagulation bath sequentially entered a first-stage washing bath, a second-stage washing bath, a third-stage washing bath, a fourth-stage washing bath, and a fifth-stage washing bath for multi-stage gradient washing;

[0234] The first-stage washing bath conditions were as follows: the composition was an aqueous ionic liquid solution with a mass fraction of 17%, the temperature was 40 ℃, and the draw speed was 80 m / min;

[0235] The second-stage washing bath conditions were as follows: the composition was an aqueous ionic liquid solution with a mass fraction of 12%, the temperature was 40 ℃, and the draw speed was 80 m / min;

[0236] The third-stage washing bath conditions were as follows: the composition was an aqueous ionic liquid solution with a mass fraction of 7%, the temperature was 40 ℃, and the draw speed was 80 m / min;

[0237] The fourth-stage washing bath conditions were as follows: the composition was an aqueous ionic liquid solution with a mass fraction of 2%, the temperature was 40 ℃, and the draw speed was 80 m / min;

[0238] The fifth-stage washing bath conditions were as follows: the composition was an aqueous ionic liquid solution with a mass fraction of 0%, the temperature was 40 ℃, and the draw speed was 80 m / min;

[0239] (5) Post-treatment

[0240] The yarns after gradient water washing, then through rinsing, oiling, heat setting to obtain regenerated cellulose industrial yarn, the regenerated cellulose industrial yarn obtained has a fineness of 1650 dtex, a breaking strength of 4.9 cN / dtex, a breaking strength CV of 3.2 %, a breaking elongation of 8.7 %, a breaking elongation CV of 3.5 %, a dry heat shrinkage at 177 ℃, 0.01 cN / dtex of 0.6 %, and a dry heat shrinkage CV at 177 ℃, 0.01 cN / dtex of 2.8 %.

[0241] The ionic liquid in the present comparative example is all 1-butyl-3-methylimidazolium chloride.

[0242] The above examples are only used to illustrate the technical solutions of the present application, and those skilled in the art should understand that the above examples do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

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 of less than or equal to 2.5%, a breaking elongation of 8-15%, a breaking elongation CV of less than or equal to 2.5%, a dry heat shrinkage at 177 ℃ and 0.01 cN / dtex of less than or equal to 0.7%, and a dry heat shrinkage CV at 177 ℃ and 0.01 cN / dtex of less than or equal to 2.5%. The regenerated cellulose multifilament is composed of 100-3000 filaments.

2. A process for the production of regenerated cellulose multifilaments according to claim 1, characterized in that The method comprises the following steps: (1) preparation of a spinning dope, wherein cellulose pulp with a degree of polymerization of 500-1500 is mixed with an ionic liquid to prepare a cellulose spinning dope with a concentration of 5-20 wt%; (2) spinning; (3) coagulation, wherein the extruded yarn is subjected to an air section and then enters a coagulation bath; the coagulation bath is composed of an ionic liquid aqueous solution with a mass fraction of 30-60%, the coagulation bath temperature is 0-30 ℃, and the draw ratio is 1-5 times, and the draw speed is 10-200 m / min; (4) multi-stage gradient washing: the yarn bundle coagulated in the coagulation bath is sequentially subjected to first-stage, second-stage, third-stage, fourth-stage and fifth-stage water washing baths for multi-stage gradient washing; the first-stage water washing bath is composed of an ionic liquid aqueous solution with a mass fraction of 10-30%, the temperature is 10-50 ℃, and the draw speed is 10-200 m / min; the second-stage water washing bath is composed of an ionic liquid aqueous solution with a mass fraction of 10-25%, the temperature is 10-50 ℃, and the draw speed is 10-200 m / min; the third-stage water washing bath is composed of an ionic liquid aqueous solution with a mass fraction of 5-20%, the temperature is 10-50 ℃, and the draw speed is 10-200 m / min; the fourth-stage water washing bath is composed of an ionic liquid aqueous solution with a mass fraction of 5-15%, the temperature is 10-50 ℃, and the draw speed is 10-200 m / min; the fifth-stage water washing bath is composed of an ionic liquid aqueous solution with a mass fraction of 0-10%, the temperature is 10-50 ℃, and the draw speed is 10-200 m / min; the ionic liquid concentration of each stage is determined according to the ionic liquid content in the yarn bundle entering each stage; the ionic liquid concentration of each stage is 5-10% lower than the ionic liquid concentration in the yarn bundle entering the stage; (5) post-treatment to obtain the regenerated cellulose multifilament; the regenerated cellulose multifilament is composed of 600-2000 filaments.

3. A process for the production of regenerated cellulose multifilaments according to claim 2, characterized in that In step (3), the coagulation bath is composed of an ionic liquid aqueous solution with a mass fraction of 30-50%, the coagulation bath temperature is 5-20 ℃, the draw ratio is 1-2 times, and the draw speed is 50-150 m / min.

4. A process for the production of regenerated cellulose multifilaments according to claim 2, characterized in that In step (4), the first-stage water washing bath is composed of an ionic liquid aqueous solution with a mass fraction of 20-30%, the water washing bath temperature is 30-50 ℃, and the draw speed is 50-150 m / min; The second-stage water washing bath has a composition of 15-25% ionic liquid aqueous solution by mass fraction, a water washing bath temperature of 30-50 DEG C, and a drawing speed of 50-150 m / min; The third-stage water washing bath has a composition of 10-20% ionic liquid aqueous solution by mass fraction, a water washing bath temperature of 30-50 DEG C, and a drawing speed of 50-150 m / min; The fourth-stage water washing bath has a composition of 5-10% ionic liquid aqueous solution by mass fraction, a water washing bath temperature of 30-50 DEG C, and a drawing speed of 50-150 m / min; The fifth-stage water washing bath has a composition of 0-5% ionic liquid aqueous solution by mass fraction, a water washing bath temperature of 30-50 DEG C, and a drawing speed of 50-150 m / min.

5. A process for the production of regenerated cellulose multifilaments according to claim 2, characterized in that In step (1), 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. A process for the production of regenerated cellulose multifilaments according to claim 5, characterized in that In step (1), the cellulose pulp has a degree of polymerization of 700-1000; and the cellulose in the spinning dope has a solid content of 8-15 wt%.

7. A process for the production of regenerated cellulose multifilaments according to claim 2, characterized in that In step (2), the prepared cellulose spinning dope is extruded through a spinneret cap for spinning; the spinneret cap has 100-3000 holes; the spinneret cap has a diameter of 0.04-0.2 mm; and the spinning temperature is 80-120 DEG C.

8. A process for the production of regenerated cellulose multifilaments according to claim 7, characterized in that In step (2), the spinneret cap has 600-2000 holes; the spinneret cap has a diameter of 0.05-0.08 mm; and the spinning temperature is 95-110 DEG C.

9. A process for the production of regenerated cellulose multifilaments according to claim 2, characterized in that, In step (5), the yarn after the multi-stage gradient water washing is subjected to rinsing, oiling and heat setting to obtain regenerated cellulose multifilament.

10. A cord made of the regenerated cellulose multifilament of claim 1.

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