Preparation method of spinning solution and regenerated cellulose fiber, compound and preparation method and application thereof

Abstract

The invention discloses a spinning solution, a preparation method of regenerated cellulose fiber, a compound, and a preparation method and application of the compound. The preparation method comprises the following steps: mixing cellulose, an N-methylmorpholine-N-oxide aqueous solution, dimethyl sulfoxide and morpholine bromine salt to obtain a spinning solution; according to the method, the viscosity of the spinning solution can be reduced, and the breaking strength of the regenerated cellulose fiber can be improved.

Description

Technical Field

[0001] The present invention relates to a spinning solution and a preparation method of regenerated cellulose fiber, and also relates to a compound and a preparation method and application thereof. Background Art

[0002] Cellulose, with its wide availability, renewability, biodegradability, and excellent biocompatibility, is becoming a key component of the textile industry's green transformation. Regenerated cellulose holds broad application prospects in a variety of fields, including textiles, healthcare, and construction. However, the preparation of regenerated cellulose fibers often faces challenges such as high viscosity, difficulty dissolving, and poor spinning stability, limiting their large-scale industrial application.

[0003] The traditional viscose process is an older cellulose regeneration technology, but its production requires the use of large amounts of toxic chemicals such as carbon disulfide, which poses a serious threat to the environment and human health. The N-methylmorpholine-N-oxide (NMMO) solvent method, with its environmentally friendly and efficient dissolution, has become an increasingly important method for producing regenerated cellulose fibers. However, the high viscosity of the cellulose / NMMO system negatively impacts spinning stability and fiber properties.

[0004] CN104419994A discloses a method for preparing a high-concentration spinning solution, comprising the steps of dissolving a proton salt and a cellulose material in a solvent comprising dimethyl sulfoxide and N-methylmorpholine-N-oxide. In the solvent, the mass ratio of dimethyl sulfoxide is greater than or equal to the mass ratio of N-methylmorpholine-N-oxide. The spinning solution has a high viscosity, and the resulting regenerated cellulose fiber has a low strength.

[0005] CN115537955A discloses a method for preparing Juncao regenerated cellulose fiber using an NMMO solvent method. The method comprises the following steps: adding a DMSO / NMMO mixed solvent to Juncao pulp, and simultaneously adding an antioxidant and cobalt chloride and mixing uniformly to obtain a mixed system; subjecting the mixed system to swelling and dissolution to obtain a Juncao fiber glue solution; and filtering, degassing, and spinning the Juncao fiber glue solution to obtain Juncao regenerated cellulose fiber. The resulting Juncao fiber glue solution has a high viscosity, but the resulting cellulose fiber has a low strength. Summary of the Invention

[0006] In view of this, one object of the present invention is to provide a method for preparing a spinning solution, which method can reduce the viscosity of the spinning solution. Another object of the present invention is to provide a method for preparing cellulose fibers, which method can increase the breaking strength of regenerated cellulose fibers. Another object of the present invention is to provide a compound. Another object of the present invention is to provide a method for preparing a compound. Another object of the present invention is to provide a use of the compound.

[0007] In one aspect, the present invention provides a method for preparing a spinning solution, comprising the following steps:

[0008] mixing cellulose, an aqueous solution of N-methylmorpholine-N-oxide, dimethyl sulfoxide and morpholine bromide to obtain a spinning solution;

[0009] Among them, the structural formula of morpholine bromide is as follows:

[0010]

[0011] Wherein, A is halogen; R1 to R5 are independently selected from H and C1 to C6 alkyl; and X is selected from C3 to C10 alkylene.

[0012] According to the preparation method of the present invention, preferably, A is bromine; R1 is selected from C1-C3 alkyl; R2-R5 are H; and X is selected from C4-C6 alkylene.

[0013] According to the preparation method of the present invention, preferably, the mass ratio of the N-methylmorpholine-N-oxide aqueous solution to dimethyl sulfoxide is 10:1-5, and the mass ratio of morpholine bromide to dimethyl sulfoxide is 0.5-1.5:100.

[0014] According to the preparation method of the present invention, preferably, the concentration of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide aqueous solution is greater than 85 wt %.

[0015] In another aspect, the present invention provides a method for preparing regenerated cellulose fiber, comprising the following steps:

[0016] (1) obtaining a spinning solution according to the above preparation method;

[0017] (2) The spinning solution is formed into regenerated cellulose fibers in a spinning device.

[0018] In another aspect, the present invention provides a compound, which is morpholinium bromide, and has the following structural formula:

[0019]

[0020] Wherein, A is halogen; R1 to R5 are independently selected from H and C1 to C6 alkyl; and X is selected from C3 to C10 alkylene.

[0021] According to the compound of the present invention, preferably, A is bromine; R1 is selected from C1-C3 alkyl; R2-R5 are H; and X is selected from C4-C6 alkylene.

[0022] According to the compound of the present invention, preferably, the compound is N-methyl-N-(4-oxobutyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxopentyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide or N-methyl-N-(4-oxoheptyl-(4'-cyanobiphenyl))morpholine bromide.

[0023] In another aspect, the present invention provides a method for preparing the above compound, comprising the steps of:

[0024] (1) reacting the compound represented by formula (IV) with the compound represented by formula (V) to obtain the compound represented by formula (II);

[0025]

[0026] (2) reacting the compound represented by formula (II) with the compound represented by formula (III);

[0027]

[0028] In formulae (II), (III), (IV) and (V), A is a halogen; R1 to R5 are independently selected from H and C1 to C6 alkyl; and X is selected from C3 to C10 alkylene.

[0029] In another aspect, the present invention provides use of the above compound in producing regenerated cellulose fibers, for reducing the viscosity of the spinning solution and increasing the breaking strength of the regenerated cellulose fibers.

[0030] The method for preparing the spinning solution of the present invention can reduce the viscosity of the spinning solution and improve the breaking strength of the regenerated cellulose fiber. According to the preferred technical solution of the present invention, the present invention can improve the structural regularity of the regenerated cellulose fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The compound obtained in Preparation Example 1 1 H NMR spectrum.

[0032] Figure 2 This is the SEM image of the regenerated cellulose fiber obtained in Example 5. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0034] <Method for Preparing Spinning Solution>

[0035] The preparation method of the spinning solution of the present invention comprises the following steps: mixing cellulose, N-methylmorpholine-N-oxide aqueous solution, dimethyl sulfoxide and morpholine bromide to obtain the spinning solution.

[0036] The structural formula of the morpholine bromide of the present invention is as follows:

[0037]

[0038] Wherein, A is halogen; R1 to R5 are independently selected from H and C1 to C6 alkyl; and X is selected from C3 to C10 alkylene.

[0039] R1 is connected to the nitrogen atom. R2-R5 represent substituents at any position on the phenyl ring. Examples of C1-C6 alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and n-hexyl.

[0040] The C3-C10 alkylene group may be a straight-chain alkyl group or a branched-chain alkyl group; preferably a straight-chain alkyl group. Examples of the C3-C10 alkylene group include, but are not limited to, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, and decylene.

[0041] Halogen may be fluorine, chlorine, bromine or iodine.

[0042] According to one embodiment of the present invention, A is bromine.

[0043] According to another embodiment of the present invention, R1 is selected from H or C1-C3 alkyl; preferably, R1 is methyl.

[0044] According to another embodiment of the present invention, X is selected from butylene, pentylene, hexylene, and heptylene. Preferably, X is hexylene.

[0045] According to a specific embodiment of the present invention, A is bromine, R1 is methyl, R2-R5 are H, and X is butylene, pentylene, hexylene, or heptylene. Specifically, the morpholinium bromide is preferably N-methyl-N-(4-oxyalkyl-(4'-cyanobiphenyl))morpholinium bromide. The alkylene group of the oxyalkyl group can be a C3-C10 alkylene group; preferably, butylene, pentylene, hexylene, or heptylene. N-methyl-N-(4-oxoalkyl-(4'-cyanobiphenyl))morpholine bromide can be N-methyl-N-(4-oxobutyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxopentyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide or N-methyl-N-(4-oxoheptyl-(4'-cyanobiphenyl))morpholine bromide; preferably N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide.

[0046] The N-methylmorpholine-N-oxide aqueous solution of the present invention can be a commercially available product. The concentration of N-methylmorpholine-N-oxide in the N-methylmorpholine-N-oxide aqueous solution of the present invention is greater than 85 wt%, preferably greater than 86 wt%, and more preferably greater than 86.7 wt%. This helps reduce the viscosity of the spinning solution.

[0047] The cellulose of the present invention can be selected from one or more of wood pulp cellulose and cotton pulp cellulose. Preferably, the cellulose is wood pulp cellulose. The degree of polymerization of the cellulose can be 200 to 1000, preferably 400 to 800, and more preferably 600 to 750. This helps reduce the viscosity of the spinning solution and ensures the breaking strength of the regenerated cellulose fiber.

[0048] The length of the cellulose may be 20 to 400 μm, preferably 40 to 300 μm.

[0049] In the present invention, the mass ratio of the aqueous solution of N-methylmorpholine-N-oxide to dimethyl sulfoxide is 10:1 to 5, preferably 10:2 to 4, and more preferably 10:3 to 4. This helps reduce the viscosity of the spinning solution and ensure the breaking strength of the regenerated cellulose fiber.

[0050] In the present invention, the mass ratio of morpholinium bromide to dimethyl sulfoxide is 0.5 to 1.5:100, preferably 0.8 to 1.2:100, and more preferably 1 to 1.1:100. This helps reduce the viscosity of the spinning solution and ensure the breaking strength of the regenerated cellulose fiber.

[0051] The mixing temperature of cellulose, N-methylmorpholine-N-oxide aqueous solution, dimethyl sulfoxide, and morpholine bromide can be 50 to 90°C, preferably 60 to 80°C. The mixing is carried out under stirring. The stirring speed can be 300 to 800 rpm, preferably 400 to 600 rpm. The mixing time can be 0.5 to 5 hours, preferably 0.8 to 3 hours, and more preferably 1 to 1.5 hours.

[0052] The concentration of cellulose in the spinning solution of the present invention may be 10 to 18 wt%, preferably 13 to 15 wt%, which is beneficial for ensuring the breaking strength of the regenerated cellulose fibers.

[0053] The viscosity of the spinning solution obtained by the present invention is significantly reduced. Compared with a spinning solution obtained without the addition of dimethyl sulfoxide and morpholinium bromide, the viscosity of the spinning solution obtained by the present invention is reduced by 60% or more, preferably 55% or more, and more preferably 50% or more. The viscosity reduction is calculated using the following formula:

[0054] Viscosity reduction range = (η1-η0) / η0×100%.

[0055] η0 represents the viscosity of the spinning solution obtained without adding dimethyl sulfoxide and morpholinium bromide, and η1 represents the viscosity of the spinning solution obtained with adding dimethyl sulfoxide and morpholinium bromide.

[0056] <Method for producing regenerated cellulose>

[0057] The method for preparing regenerated cellulose of the present invention comprises the following steps: (1) preparing a spinning solution; and (2) obtaining regenerated cellulose fibers. The steps for preparing the spinning solution are as described above and are not repeated here. The steps for obtaining regenerated cellulose fibers are described below.

[0058] The spinning solution is formed into regenerated cellulose fibers in a spinning device.

[0059] The spinning solution is degassed and then formed in a spinning device to obtain regenerated cellulose fibers. Specifically, the spinning solution is placed in a vacuum drying device and degassed at a temperature of 40 to 70° C., preferably 45 to 60° C., for 30 to 90 minutes, preferably 50 to 70 minutes, to obtain a degassed spinning solution.

[0060] The degassed spinning solution is delivered to the spinneret via a metering pump, extruded, and then formed in a coagulation bath to obtain nascent fibers. Drawing can be performed during the coagulation process to facilitate smooth spinning. The distance between the spinneret and the coagulation bath is 0.5 to 5 cm, preferably 1 to 4 cm, and more preferably 2 to 3 cm. The diameter of the spinneret's orifice is 80 to 150 μm, preferably 80 to 120 μm, and more preferably 100 to 120 μm. The spinning temperature can be 60 to 100°C, preferably 70 to 90°C, and more preferably 80 to 95°C. The coagulation bath can be formed from water or an aqueous solution of N-methylmorpholine-N-oxide. The temperature of the coagulation bath can be 20 to 40°C, and preferably 25 to 30°C.

[0061] The spun fibers are washed, dried, and oiled to obtain regenerated cellulose fibers. The washing, drying, and oiling can be performed using equipment and process parameters well known in the art, and the steps are not described here.

[0062] The breaking strength of the regenerated cellulose fibers obtained by the present invention is significantly improved. Compared with regenerated cellulose fibers obtained without the addition of dimethyl sulfoxide and morpholinium bromide, the breaking strength of the regenerated cellulose fibers obtained by the present invention is increased by 35-160%, preferably 70-150%, and more preferably 100-135%. The increase in breaking strength is calculated using the following formula:

[0063] Increase in breaking strength = (X1-X0) / X0×100%.

[0064] X0 represents the breaking strength of the regenerated cellulose fiber obtained without adding dimethyl sulfoxide and morpholinium bromide, and X1 represents the breaking strength of the regenerated cellulose fiber obtained with adding dimethyl sulfoxide and morpholinium bromide.

[0065] <Compound>

[0066] The compound of the present invention is shown in formula (I):

[0067]

[0068] Wherein, A is halogen; R1 to R5 are independently selected from H and C1 to C6 alkyl; and X is selected from C3 to C10 alkylene.

[0069] R1 is connected to the nitrogen atom. R2-R5 represent substituents at any position on the phenyl ring. Examples of C1-C6 alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and n-hexyl.

[0070] The C3-C10 alkylene group may be a straight-chain alkyl group or a branched-chain alkyl group; preferably a straight-chain alkyl group. Examples of the C3-C10 alkylene group include, but are not limited to, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, and decylene.

[0071] Halogen may be fluorine, chlorine, bromine or iodine.

[0072] According to one embodiment of the present invention, A is bromine.

[0073] According to another embodiment of the present invention, R1 is selected from H or C1-C3 alkyl; preferably, R1 is methyl.

[0074] According to another embodiment of the present invention, X is selected from butylene, pentylene, hexylene, and heptylene. Preferably, X is hexylene.

[0075] According to one embodiment of the present invention, A is bromine, R1 is methyl, R2-R5 are H, and X is butylene, pentylene, hexylene, or heptylene. Specifically, the compound of the present invention is morpholinium bromide; preferably N-methyl-N-(4-oxyalkyl-(4'-cyanobiphenyl))morpholinium bromide. The alkylene group of the oxyalkyl group can be a C3-C10 alkylene group; preferably, butylene, pentylene, hexylene, or heptylene. N-methyl-N-(4-oxoalkyl-(4'-cyanobiphenyl))morpholine bromide can be N-methyl-N-(4-oxobutyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxopentyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide or N-methyl-N-(4-oxoheptyl-(4'-cyanobiphenyl))morpholine bromide; preferably N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide.

[0076] <Method for preparing compound>

[0077] The preparation method of the compound of the present invention comprises the following steps: (1) obtaining the compound represented by formula (II); and (2) obtaining the compound of the present invention. Detailed description is given below.

[0078] The compound represented by formula (IV) is reacted with the compound represented by formula (V) to obtain the compound represented by formula (II).

[0079]

[0080] A, R2 to R5 and X have the same meanings as described above.

[0081] The molar ratio of the compound represented by formula (IV) to the compound represented by formula (V) is 1:(1-1.8); preferably 1:(1.3-1.6).

[0082] The compound represented by formula (IV) and the compound represented by formula (V) can react in the presence of potassium carbonate and acetone to obtain a first reaction product. The molar ratio of the compound represented by formula (IV) to potassium carbonate can be 1:(1.5-3); preferably 1:(1.8-2.5); more preferably 1:(2-2.2). The molar ratio of the compound represented by formula (IV) to acetone can be 1:(1.5-3); preferably 1:(1.8-2.5); more preferably 1:(2-2.2). This is conducive to improving the yield.

[0083] The reaction temperature can be 40-80°C, preferably 50-70°C, and more preferably 55-65°C. The reaction time can be 7-18 hours, preferably 10-16 hours, and more preferably 12-14 hours. This is beneficial to improving the yield.

[0084] Acetone is removed from the first reaction product obtained by reacting the compound represented by formula (IV) with the compound represented by formula (V) by rotary evaporation. The first reaction product, from which acetone has been removed, is poured into a mixture of water and chloroform, and then separated to obtain an organic phase. The volume ratio of water to chloroform can be 1:(1-2).

[0085] The solid product in the organic phase is separated, washed with water, and then washed with saturated brine to obtain a washed solid product. The organic phase in the washed solid product is removed by rotary evaporation to obtain a crude intermediate. The crude intermediate is recrystallized from petroleum ether and then dried to obtain a compound represented by formula (II).

[0086] The compound represented by formula (II) and the compound represented by formula (III) are reacted to obtain the compound of the present invention.

[0087]

[0088] The meaning represented by R1 is as described above.

[0089] The molar ratio of the compound represented by formula (II) to the compound represented by formula (III) is 1:(1 to 1.8); preferably 1:(1.3 to 1.6).

[0090] The compound represented by formula (II) and the compound represented by formula (III) can react in the presence of acetonitrile to obtain a second reaction product.

[0091] The reaction temperature can be 50-90°C, preferably 60-85°C, and more preferably 65-80°C. The reaction time can be 3-16 hours, preferably 6-15 hours, and more preferably 8-13 hours. This is beneficial to improving the yield of the product.

[0092] The acetonitrile in the second reaction product is removed by rotary evaporation. The excess compound represented by formula (III) in the second reaction product is removed by extraction. The extractant can be diethyl ether. The extractant is removed by suction filtration to obtain a crude product. The crude product is recrystallized from ethyl acetate and then dried to obtain the compound of the present invention, as represented by formula (I).

[0093] The yield of the compound of the present invention obtained by the above method is 75% or more, preferably 80% or more, and more preferably 85% or more.

[0094] <Uses of Compounds>

[0095] The present invention also provides a use of a compound in the production of regenerated cellulose fibers, which is used to reduce the viscosity of the spinning solution and increase the breaking strength of the regenerated cellulose fibers. The above compound is shown in formula (I), and the specific structure is as described above.

[0096] Cellulose, an aqueous solution of N-methylmorpholine-N-oxide, dimethyl sulfoxide, and morpholine bromide are mixed to obtain a spinning solution. The specific conditions are as described above. Compared to a spinning solution obtained without the addition of dimethyl sulfoxide and morpholine bromide, the viscosity of the spinning solution obtained in the present invention is reduced by at least 60%, preferably at least 55%, and more preferably at least 50%. The viscosity reduction is calculated using the following formula:

[0097] Viscosity reduction range = (η1-η0) / η0×100%.

[0098] η0 represents the viscosity of the spinning solution obtained without adding dimethyl sulfoxide and morpholinium bromide, and η1 represents the viscosity of the spinning solution obtained with adding dimethyl sulfoxide and morpholinium bromide.

[0099] The spinning solution is formed into regenerated cellulose fibers in a spinning apparatus. The specific conditions are as described above. Compared to regenerated cellulose fibers obtained without the addition of dimethyl sulfoxide and morpholinium bromide, the regenerated cellulose fibers obtained in the present invention have an increase in breaking strength of 35-160%, preferably 70-150%, and more preferably 100-135%. The increase in breaking strength is calculated using the following formula:

[0100] Increase in breaking strength = (X1-X0) / X0×100%.

[0101] X0 represents the breaking strength of the regenerated cellulose fiber obtained without adding dimethyl sulfoxide and morpholinium bromide, and X1 represents the breaking strength of the regenerated cellulose fiber obtained with adding dimethyl sulfoxide and morpholinium bromide.

[0102] The test method is described as follows:

[0103] 1 H NMR: The compounds of the present invention were dissolved in deuterated DMSO and analyzed using Bruker

[0104] 400M liquid nuclear magnetic resonance spectrometer for testing.

[0105] SEM test: The test was performed using a Gemini SEM 500 scanning electron microscope produced by ZEISS, Germany.

[0106] Viscosity of spinning solution: The spinning solution after degassing was subjected to steady-state rotational shear test at three temperatures: 60°C, 80°C and 100°C using HAAKE MARS rheometer. The shear rate was adjusted from 0.1s to - 1 increments to 100s - 1. Record the corresponding shear viscosity curve. The unit of viscosity is Pa·s.

[0107] Regenerated cellulose fiber breaking strength: Measured using an electronic single fiber strength tester according to the method specified in GB / T 14337-2008. The test conditions are a tensile speed of 50 mm / min, a return speed of 80 mm / min, an initial tensile force of 10 cN, a clamp distance of 10 mm, a test temperature of 25°C, and a relative humidity of 40 BH%. The fibers were dried at 50°C for 2 hours before testing. Breaking strength is reported in cN / dtex.

[0108] The raw materials are as follows:

[0109] The wood pulp cellulose used in the following examples and comparative examples has a degree of polymerization of 702 and was purchased from Shandong Hailong Co., Ltd.

[0110] Preparation Example 1

[0111] The synthetic route of N-methyl-N-oxyhexyl-(4'-cyanobiphenyl)morpholine bromide is as follows:

[0112]

[0113] The detailed steps are as follows:

[0114] 30 mmol of p-cyanodiphenol, 60 mmol of potassium carbonate, 45 mmol of 1,6-dibromohexane, and 60 mmol of acetone were mixed and reacted at 60°C for 12 hours to obtain a first reaction product. The acetone in the first reaction product was removed by rotary evaporation, and then the product was poured into a 1:1 mixture of chloroform and water by volume for extraction to obtain an organic phase. The solid product in the organic phase was separated, washed three times with water, and then washed once with saturated brine to obtain a washed solid product. The chloroform in the washed solid product was removed by rotary evaporation to obtain a crude intermediate. The crude intermediate was recrystallized from petroleum ether and then dried under vacuum to obtain the intermediate.

[0115] 30 mmol of the intermediate, 45 mmol of 4-methylmorpholine, and acetonitrile were mixed and stirred at 80°C for 12 hours to obtain a second reaction product. The reaction progress was assessed by TLC. The acetonitrile in the second reaction product was removed by rotary evaporation, followed by extraction of the excess 4-methylmorpholine with ether. The ether was then removed by filtration to obtain a crude product. The crude product was purified by recrystallization from ethyl acetate and then vacuum dried to obtain the compound morpholine bromide, namely N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide. The yield reached 85%.

[0116] Figure 1The figure shows the NMR spectrum of the compound obtained in Preparation Example 1. The peaks at 6.98-7.95 ppm are characteristic of H on the benzene ring, 4.04 ppm are characteristic of H on the flexible chain affected by oxygen atoms, 3.78-3.98 ppm are characteristic of H on the methylmorpholine group affected by oxygen atoms, 3.36-3.51 ppm are characteristic of H on the methylmorpholine group and H on the flexible chain affected by nitrogen atoms, 3.13 ppm are characteristic of H on the methyl group of the methylmorpholine group, and 1.38-1.74 ppm are characteristic of H on the methylene group of the flexible chain not affected by other atoms.

[0117] A larger amount of N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide was obtained by scaling up the experiment and used for later use.

[0118] Preparation Examples 2 to 4

[0119] Except that 1,6-dibromohexane was replaced by 1,4-dibromobutane, 1,5-dibromopentane and 1,7-dibromoheptane, respectively, the other conditions were the same as those in Preparation Example 1, and the compounds N-methyl-N-(4-oxobutyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxopentyl-(4'-cyanobiphenyl))morpholine bromide and N-methyl-N-(4-oxoheptyl-(4'-cyanobiphenyl))morpholine bromide were obtained, respectively.

[0120] Examples 1 to 9

[0121] The wood pulp cellulose is crushed into cellulose with a length of 49 to 297 μm by a high-speed crusher.

[0122] Cellulose, an N-methylmorpholine-N-oxide (NMMO) aqueous solution, a cosolvent (dimethyl sulfoxide (DMSO), and the N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide of Preparation Example 1 were mixed and stirred at 70° C. and 500 rpm for 1 hour to obtain a cellulose liquid crystal spinning solution having a cellulose concentration of 13 wt%. The mass ratio of the NMMO aqueous solution to DMSO and the mass ratio of the compound of the present invention (N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide) to DMSO are shown in Table 1; the NMMO concentration of the NMMO aqueous solution was greater than 86.7 wt%. The viscosity η1 of the cellulose liquid crystal spinning solution was measured.

[0123] The cellulose liquid crystal spinning solution was placed in a vacuum drying oven and degassed at 50°C for 60 minutes. The degassed cellulose liquid crystal spinning solution was pumped to a spinneret via a metering pump. The spinning solution was extruded and placed into a coagulation bath (water) to form spun fibers. The distance between the spinneret and the coagulation bath was 2 cm; the spinneret orifice diameter was 110 μm; and the spinning temperature was 80°C. The spun fibers were washed, dried, and oiled to produce regenerated cellulose fibers. The breaking strength (X1) of the regenerated cellulose fibers was measured.

[0124] According to SEM observation, the regenerated cellulose fibers obtained in Examples 1 to 9 have good structural regularity. The SEM image of the regenerated cellulose fibers of Example 5 is as follows: Figure 2 As shown. Figure 2 It can be seen that the structural regularity of the regenerated cellulose fibers is very good.

[0125] Comparative Example 1

[0126] The same conditions as in Example 1 were used, except that the cosolvent (dimethyl sulfoxide (DMSO)) and N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholinium bromide were omitted, to produce a cellulose liquid crystal spinning solution having a cellulose concentration of 13 wt%. The viscosity η0 of the cellulose liquid crystal spinning solution was measured. Regenerated cellulose fibers were then produced according to the conditions of Example 1. The breaking strength X0 of the regenerated cellulose fibers was measured.

[0127] Increase in breaking strength = (X1-X0) / X0×100%.

[0128] The increase in breaking strength is shown in Table 1.

[0129] Table 1

[0130]

[0131] As shown in the table, the combination of DMSO and the compound of the present invention can increase the breaking strength of regenerated cellulose fibers. When the mass ratio of NMMO aqueous solution to DMSO is 10:3, the breaking strength increase is even greater. The highest increase in breaking strength is achieved when the mass ratio of the compound of the present invention to DMSO is 1:100.

[0132] Comparative Examples 2-3

[0133] Dimethyl sulfoxide (DMSO) was replaced with dimethylformamide (DMF) or dimethylacetamide (DMAC), and the remaining conditions were the same as in Example 1 to obtain a cellulose liquid crystal spinning solution having a cellulose concentration of 13 wt %. The viscosity η1 of the cellulose liquid crystal spinning solution was measured.

[0134] Viscosity reduction range = (η1-η0) / η0×100%.

[0135] The extent of viscosity reduction of the cellulose liquid crystal spinning solution is shown in Table 2. As can be seen from the table, DMSO has the best effect on reducing the viscosity of the cellulose liquid crystal spinning solution.

[0136] Table 2

[0137] serial number Co-solvent type Viscosity reduction of cellulose liquid crystal spinning solution Comparative Example 2 DMAC 20％ Comparative Example 3 DMF 40％ Example 1 DMSO ＞50％

[0138] The present invention is not limited to the above-mentioned embodiments. Any modification, improvement, or substitution that can be conceived by those skilled in the art without departing from the essential content of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing a spinning solution, characterized in that: The steps include: mixing cellulose, an aqueous solution of N-methylmorpholine-N-oxide, dimethyl sulfoxide and morpholine bromide to obtain a spinning solution; Among them, the structural formula of morpholine bromide is as follows: Wherein, A is halogen; R1 to R5 are independently selected from H and C1 to C6 alkyl; and X is selected from C3 to C10 alkylene.

2. The preparation method according to claim 1, characterized in that A is bromine; R1 is selected from C1-C3 alkyl; R2-R5 are H; and X is selected from C4-C6 alkylene.

3. The preparation method according to claim 1, characterized in that The mass ratio of the N-methylmorpholine-N-oxide aqueous solution to dimethyl sulfoxide is 10:1-5, and the mass ratio of morpholine bromide to dimethyl sulfoxide is 0.5-1.5:

100.

4. The preparation method according to claim 1, characterized in that In the aqueous solution of N-methylmorpholine-N-oxide, the concentration of N-methylmorpholine-N-oxide is greater than 85 wt %.

5. A method for preparing regenerated cellulose fiber, characterized in that: The steps include: (1) obtaining a spinning solution according to the preparation method according to any one of claims 1 to 4; (2) The spinning solution is formed into regenerated cellulose fibers in a spinning device.

6. A compound, characterized in that The compound is morpholine bromide, and its structural formula is as follows: Wherein, A is halogen; R1 to R5 are independently selected from H and C1 to C6 alkyl; and X is selected from C3 to C10 alkylene.

7. The compound according to claim 6, characterized in that A is bromine; R1 is selected from C1-C3 alkyl; R2-R5 are H; and X is selected from C4-C6 alkylene.

8. The compound according to claim 6, characterized in that The compound is N-methyl-N-(4-oxobutyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxopentyl-(4'-cyanobiphenyl))morpholine bromide, N-methyl-N-(4-oxohexyl-(4'-cyanobiphenyl))morpholine bromide or N-methyl-N-(4-oxoheptyl-(4'-cyanobiphenyl))morpholine bromide.

9. The method for preparing the compound according to any one of claims 6 to 8, characterized in that: The steps include: (1) reacting the compound represented by formula (IV) with the compound represented by formula (V) to obtain the compound represented by formula (II); (2) reacting the compound represented by formula (II) with the compound represented by formula (III); In formulae (II), (III), (IV) and (V), A is a halogen; R1 to R5 are independently selected from H and C1 to C6 alkyl; and X is selected from C3 to C10 alkylene.

10. Use of the compound according to any one of claims 6 to 8 in the production of regenerated cellulose fibers, characterized in that It serves to reduce the viscosity of the spinning solution and to increase the breaking strength of the regenerated cellulose fibers.

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