A modal fiber with ultra-high wet modulus variation and its preparation process

Abstract

This application relates to the field of modal fiber, specifically a preparation process for a modal fiber with ultra-high wet modulus variation. The relevant process parameters are set as follows: the degree of polymerization of alkalized cellulose after aging is 350-750; the weight percentage of carbon disulfide added to methyl cellulose is 36-48%; the viscose aging degree is 10-16 mL (10% NH4Cl); in the spinning coagulation bath, the sulfuric acid concentration is 65-105 g / L, the sodium sulfate concentration is 105-210 g / L, the zinc sulfate concentration is 45-85%, and the coagulation bath temperature is 20-55℃; the fiber draw ratio is 90-120%. This process has the advantage of further improving the wet modulus of the modified modal fiber while ensuring high fiber hook strength.

Description

Technical Field

[0001] This application relates to the technical field of modal fibers, and in particular to a modal fiber with ultra-high wet modulus variation and its preparation process. Background Technology

[0002] Viscose fiber, similar to cotton fiber, possesses the unique comfort of cellulosic fabrics, especially in terms of moisture absorption and breathability. However, viscose fiber swells dramatically when wet, significantly reducing its wet breaking strength. Its low wet modulus makes it prone to elongation under relatively light loads when wet, causing fabrics to deform easily during washing and rubbing, shrink after drying, and exhibit dimensional instability, severely impacting the fabric's performance. To improve the quality of viscose fiber, high wet modulus viscose fiber, namely Modal fiber, has been developed.

[0003] Modal fibers mainly include two types: Polinosic fiber and high wet modulus modal fiber. Polinosic fiber possesses excellent properties such as high breaking strength, low breaking elongation, and high wet modulus, but it has low hook strength, high fiber brittleness, and poor fatigue performance. High wet modulus modal fiber, developed based on Polinosic fiber, aims to overcome the shortcomings of Polinosic fiber, such as low hook strength, high brittleness, and complex production process. It improves the hook strength of the fiber, but the dimensional stability and wrinkle resistance of the fabric are significantly lower than those of Polinosic fiber.

[0004] Regarding the aforementioned technologies, the inventors believe that while existing high wet modulus variable modal fibers have high hook strength, their wet modulus is insufficient. Developing variable modal fibers with higher wet modulus while ensuring high hook strength can further improve the dimensional stability and application range of fiber-made products. Summary of the Invention

[0005] In order to further improve the wet modulus of modified modal fibers while ensuring high fiber hook strength, this application provides a modified modal fiber with ultra-high wet modulus and its preparation process.

[0006] In a first aspect, this application provides a preparation process for ultra-high wet modulus variable modal fibers, employing the following technical solution:

[0007] A process for preparing a modal fiber with ultra-high wet modulus variation is characterized by comprising the following steps: alkalization of pulp, aging of pulp cellulose, xanthation and dissolution of pulp cellulose, filtration of viscose, maturation of viscose, degassing of viscose, treatment of spinning solution, preparation of nascent filaments, drawing of nascent filaments, desulfurization of fibers, bleaching of fibers, washing of fibers, oiling of fibers, and drying of fibers.

[0008] The preparation process includes the following parameters: the degree of polymerization of alkalized cellulose after aging is 350-750; the weight percentage of carbon disulfide added to methyl cellulose is 36-48%; the viscose aging degree is 10-16 mL (10% NH4Cl); in the spinning coagulation bath, the sulfuric acid concentration is 65-105 g / L, the sodium sulfate concentration is 105-210 g / L, the zinc sulfate concentration is 45-85 g / L, and the coagulation bath temperature is 20-55℃; the fiber draw ratio is 90-120%.

[0009] By adopting the above technical solution, eight factors that directly affect the dry breaking strength, wet modulus, and hook strength of modal fibers were selected: degree of polymerization of alkalized cellulose after aging, amount of xanthated carbon disulfide added, viscose maturity, concentration of sulfuric acid, sodium sulfate, and zinc sulfate in the coagulation bath, coagulation bath temperature, and fiber draw ratio. Orthogonal experiments and range analysis were used to analyze the influence trends of these eight factors on the dry breaking strength, wet modulus, and hook strength of modal fibers. The results demonstrated that the main factors affecting the wet modulus and dry breaking strength, and their order of influence, are fiber draw ratio and amount of carbon disulfide added. The most important factors affecting modal fiber hook strength are the degree of polymerization of alkalized cellulose and the concentration of sulfuric acid in the coagulation bath, with the fiber draw ratio being the most significant factor and the other three being secondary factors. The main factors affecting fiber hook strength, in order of influence, are the zinc sulfate concentration in the coagulation bath, the sodium sulfate to sulfuric acid ratio, the sulfuric acid concentration, and the degree of polymerization of alkalized cellulose after aging. The zinc sulfate concentration is the most significant factor, with the other three being secondary factors. This led to the determination of an optimized process combination, enabling modal fiber to achieve excellent wet modulus while also exhibiting high hook strength, greatly improving the performance of modal fiber and expanding its application prospects.

[0010] As a preferred embodiment, the preparation process includes the following process parameters: the degree of polymerization of alkalized cellulose after aging is 400-600, the mass percentage of carbon disulfide added to methyl cellulose is 40-48%, and the viscose aging degree is 14-16 mL (10% NH4Cl); in the spinning coagulation bath, the sulfuric acid concentration is 75-95 g / L, the sodium sulfate concentration is 135-180 g / L, the zinc sulfate concentration is 55-85 g / L, the coagulation bath temperature is 30-45℃, and the fiber draw ratio is 110-120%.

[0011] By adopting the above technical solutions and further optimizing the process parameters, the wet modulus and hook strength of modal fibers can be further improved.

[0012] Preferably, the pulp is wood pulp or bamboo pulp, the average degree of polymerization of the pulp is >600, and the methyl cellulose content is >92%.

[0013] By adopting the above technical solution, when the pulp in this application is wood pulp, high-performance modal fiber can be prepared.

[0014] As a preferred embodiment, the alkalization step of the pulp is as follows:

[0015] The pulp is soaked in a NaOH solution with a concentration of 180-250 g / L, and a penetrant is added. The penetrant accounts for 0.05-5% of the mass percentage of cellulose A in the pulp. The reaction time is 40-60 min, the reaction temperature is 30-50℃, and the bath ratio is 1:(3-6).

[0016] By adopting the above technical solution, and by limiting the concentration of sodium hydroxide and the alkalization temperature, and by selecting the amount of penetrant, the pulp can be alkalized more thoroughly, and under these process parameters, there is no significant impact on the performance of the final modal fiber.

[0017] Preferably, the xanthation and dissolution of the pulp cellulose are as follows:

[0018] A dry xanthation process is adopted, with an initial xanthation temperature of 25-30℃. The xanthated cellulose sulfonate is dissolved in a NaOH solution with a concentration of 15-20 g / L at a temperature of 0-4℃. The volume ratio of cellulose sulfonate to NaOH solution is 1:(3-5). The obtained cellulose xanthate solution is ground to obtain a viscose.

[0019] By adopting the above technical solution, and by controlling the amount of carbon disulfide added, as well as the xanthation initiation temperature, sodium hydroxide concentration, and temperature, the residual esterification degree of the fiber when it leaves the coagulation bath can be maintained at more than 15%, which can obtain a greater plastic elongation rate during stretching, thereby obtaining fibers with higher strength and wet modulus.

[0020] Preferably, the treatment steps of the spinning solution include the following:

[0021] Add a composite modifier to the spinning solution at a mass of 0.5-4% of the mass of cellulose A in the viscose; then add a defoamer at a volume of 0.02-0.1% of the spinning solution.

[0022] By adopting the above technical solution and controlling the dosage of composite modifier and defoamer, the molding stability of the viscose is greatly changed, enabling stable cellulose filaments to be obtained in a low-acid, low-salt coagulation bath.

[0023] Preferably, the preparation steps of the nascent filaments include the following:

[0024] The treated spinning solution is coagulated in a spinning coagulation bath, which consists of H2SO4, ZnSO4, Na2SO4, coagulation bath additives and water. The concentration of the coagulation bath additives is 0.2-0.7 g / L, and the immersion time of the filaments in the coagulation bath is 1-2 seconds.

[0025] By adopting the above technical solutions, the grain size in the fiber can be limited, and fibers with high hook strength can be produced; the regeneration rate of cellulose xanthate can be controlled to avoid the inability to obtain higher plastic tensile strength after complete regeneration; and higher hook strength and higher wet modulus of the fiber can be achieved at the same time.

[0026] Preferably, in the preparation step of the nascent filament, the spinning speed is 25-40 m / min.

[0027] Secondly, this application provides a modal fiber with ultra-high wet modulus variation, employing the following technical solution:

[0028] A modal fiber with ultra-high wet modulus variation, wherein the ultra-high wet modulus variation modal fiber is prepared by the above-mentioned preparation process of a modal fiber with ultra-high wet modulus variation.

[0029] By adopting the above technical solutions, the wet modulus of the modal fibers prepared in this application is above 15.2 cN / dtex, the dry breaking strength is above 3.31 cN / dtex, and the hook strength exceeds 0.72 cN / dtex. This indicates that the modal fibers prepared in this application achieve excellent wet modulus performance and high hook strength. Compared with international and domestic leading modal fiber products and international modal fiber standards, the wet modulus of the modal fibers prepared in this application exceeds that of international and domestic leading products by 29.2%, exceeds the international standard value by 83.4%, and exceeds the current textile industry standard value by 61%. The hook strength of the fibers is superior to that of leading domestic and foreign products, and other performance standards meet the current textile industry standards.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] 1. Eight factors that directly affect the dry breaking strength, wet modulus, and hook strength of Modal fibers were selected: degree of polymerization of alkalized cellulose (after aging), amount of xanthated carbon disulfide added, viscose maturity, and concentrations of sulfuric acid, sodium sulfate, and zinc sulfate in the coagulation bath, as well as coagulation bath temperature and fiber draw ratio. Orthogonal experiments and range analysis were used to analyze the influence trends of these eight factors on the dry breaking strength, wet modulus, and hook strength of Modal fibers. The results showed that the main factors affecting the wet modulus and dry breaking strength, and their order of influence, were: fiber draw ratio, amount of carbon disulfide added, etc. The degree of polymerization of alkalized cellulose and the concentration of sulfuric acid in the coagulation bath are the most important factors, with the fiber draw ratio being the most important, and the other three being secondary factors. The main factors affecting the fiber hook strength, in order of influence, are the zinc sulfate concentration in the coagulation bath, the sodium sulfate to sulfuric acid ratio, the sulfuric acid concentration, and the degree of polymerization of alkalized cellulose. The zinc sulfate concentration is the most important factor, and the other three are secondary factors. Thus, the optimized process combination was determined, enabling Modal fiber to achieve excellent wet modulus and high hook strength, which greatly improves the performance of Modal fiber and expands its application prospects.

[0032] 2. The wet modulus of the modal fibers prepared in this application is above 15.2 cN / dtex, the dry breaking strength is above 3.31 cN / dtex, and the hook strength exceeds 0.72 cN / dtex. This indicates that the modal fibers prepared in this application achieve excellent wet modulus performance and high hook strength. Compared with international and domestic leading modal fiber products and international modal fiber standards, the wet modulus of the fibers prepared in this application exceeds that of international and domestic leading products by 29.2%, exceeds the international standard value by 83.4%, and exceeds the current textile industry standard value by 61%. The hook strength of the fibers is superior to that of leading domestic and foreign products, and other performance standards meet the current textile industry standards. Detailed Implementation

[0033] The following provides a more detailed description of this application in conjunction with specific details.

[0034] raw material

[0035] The pulp used in this application is wood pulp or bamboo pulp, wherein the content of methyl cellulose in the pulp is >92% and the average degree of polymerization is >600; the remaining raw materials are commercially available products.

[0036] Example

[0037] This application uses an orthogonal experiment to study eight factors that directly affect the dry breaking strength, wet modulus, and hook strength of modal fibers: degree of polymerization of alkalized cellulose, amount of xanthated carbon disulfide added, viscose maturity, concentration of sulfuric acid, sodium sulfate, and zinc sulfate in the coagulation bath, coagulation bath temperature, and fiber draw ratio (represented by A, B, C, D, E, F, G, and H in this specification). 27 (3 13 The influence trends of eight factors on the dry breaking strength, wet modulus, and hook strength of modal fibers were analyzed using range analysis. The main factors and important procedural sequences affecting dry breaking strength, wet modulus, and hook strength were identified, and the optimal process combination was determined. The levels of the eight selected factors are as follows:

[0038] Degree of polymerization of alkalized cellulose after aging (A): Select three degree of polymerization levels, namely 350-400, 400-600, and 600-750; Amount of xanthated carbon disulfide added (B): Select three levels, with the weight percentage of carbon disulfide to methyl cellulose being 36-38%, 38-40%, and 40-48%, respectively.

[0039] Adhesive maturity (C) (10% NH4Cl): Select three levels: 10-12 mL, 12-14 mL, and 14-16 mL.

[0040] Sulfuric acid concentration (D) in the coagulation bath: Select three levels, namely 65-75 g / L, 75-95 g / L, and 95-105 g / L;

[0041] Sodium sulfate concentration (E) in the coagulation bath: The sodium sulfate concentration in the solid bath depends on the sulfuric acid concentration. Three levels of low, medium and high relative to the sulfuric acid concentration were selected, as shown in Table 1.

[0042] Table 1. Table of sodium sulfate dosage factors in the embodiments of this application.

[0043]

[0044] Zinc sulfate concentration (F) in the coagulation bath: Three levels were selected, namely 45-50 g / L, 51-55 g / L, and 55-85 g / L;

[0045] Condensation bath temperature (G): Select three levels: 20-30℃, 30-45℃, and 45-55℃.

[0046] Fiber draw ratio (H): Select three levels: 90-100%, 100-110%, and 110-120%.

[0047] Examples 1-27

[0048] A modal fiber with ultra-high wet modulus variation, the parameters of its preparation process are shown in Table 2, the pulp used is wood pulp, and the preparation process is as follows:

[0049] 1) Alkalization of pulp: Dissolve the pulp in a 235 g / L NaOH solution, add penetrant JL-EBZ, the penetrant JL-EBZ accounts for 1% of the mass percentage of cellulose methyl ester, the impregnation time is 50 min, the impregnation temperature is 45℃, and the bath ratio is 1:5.5;

[0050] 2) Aged pulp cellulose: The alkalized cellulose treated in step 1) is placed into an aging device, the temperature is controlled at 35℃, and the aging time is 100min;

[0051] 3) Xanthation and dissolution of pulp cellulose: A dry xanthation process was adopted. The alkalized cellulose treated in step 2) was reacted with carbon disulfide. The mass ratio of carbon disulfide to cellulose A in the pulp was 43%, the reaction time was 1 hour, and the initial reaction temperature was 27℃. The xanthated cellulose sulfonate was dissolved in a 17 g / L NaOH solution at 2℃. The volume ratio of cellulose sulfonate to NaOH solution was 1:3.5. The obtained cellulose xanthate solution was ground 7 times to form a viscose.

[0052] 4) Filtration of adhesive: The adhesive processed in step 3) is filtered using a filter machine;

[0053] 5) Adhesive curing: The adhesive treated in step 4) is cured in a curing tank at a controlled temperature of 26-28℃ for 8 hours.

[0054] 6) Degassing of viscose: The spinning solution obtained in step 5) is subjected to a continuous and rapid degassing method to remove air bubbles from the viscose, so as to obtain a spinning solution that can be used for spinning.

[0055] 7) Treatment of spinning solution: Add composite modifier JL-FS to the spinning solution obtained in step 6), the composite modifier accounting for 2.8% of the mass percentage of cellulose A; then add defoamer CD-FFA01, the amount of defoamer added is 0.06% of the volume of spinning solution;

[0056] 8) Preparation of nascent filaments: The spinning solution treated in step 7) is solidified in a spinning coagulation bath. The coagulation bath consists of H2SO4, ZnSO4, Na2SO4, coagulation bath additives and water (H2SO4, ZnSO4 and Na2SO4 are shown in Table 2). The concentration of the coagulation bath additives is 0.5 g / L. The coagulation bath temperature is shown in Table 2. Spinning is carried out using a precious metal alloy spinneret. The spinning speed is 30 m / min. The immersion time of the filaments in the coagulation bath is 1.5 seconds.

[0057] 9) Drafting of nascent filaments: The nascent filaments treated in step 8) were plastically drafted in a two-bath chamber. The fiber drafting rate is shown in Table 2.

[0058] 10) Desulfurization of fibers: Immerse the fibers treated in step 9) in a NaOH solution with a concentration of 3 g / L for 15 seconds at a solution temperature of 80°C.

[0059] 11) Fiber bleaching: Immerse the fibers treated in step 10) in a sodium hypochlorite solution with a concentration of 1.2 g / L for 20 seconds at a solution temperature of 55°C.

[0060] 12) Washing the fibers: Immerse the fibers treated in step 11) in hot water at 70°C for 60 seconds;

[0061] 13) Oiling the fibers: Immerse the fibers treated in step 12) in an oil bath solution of 7 g / L, at a temperature of 70°C, for 15 seconds.

[0062] 14) Drying of fibers: The fibers processed in step 13) are dried to obtain bamboo raw material modal fibers.

[0063] Table 2 Process parameters for Examples 1-27

[0064]

[0065] Performance testing of Examples 1-27

[0066] Detection methods

[0067] High wet modulus variation modal fibers were prepared according to the preparation process of Examples 1-27, and then tested according to the following test methods. The test results are shown in Tables 3 and 4.

[0068] Sampling regulations: Sampling of performance items shall be carried out in accordance with the product sampling methods specified in GB / T 14334.

[0069] The wet modulus, dry breaking strength and hook strength shall be tested in accordance with the methods specified in GB / T 14337.

[0070] Table 3 Detection Results

[0071]

[0072]

[0073] Table 4 Range Analysis

[0074]

[0075]

[0076] As can be seen from Examples 1-27 and the detection data in Tables 3 and 4, the orthogonal experiment (L... 27 (3 13 According to the range analysis, the influence of the eight factors (AH) on wet modulus, dry fracture strength and hook strength, in descending order, is as follows: Wet modulus: HBADECGF;

[0077] Dry fracture strength: HBADCEFG;

[0078] Hook strength: FEDAGHBC.

[0079] The above analysis shows that the high wet modulus variable modal fiber exhibits excellent performance when the process parameters are within the following range: alkalized cellulose polymerization degree (after aging) of 400-600, carbon disulfide addition to methyl cellulose weight percentage of 40-48%, viscose maturity of 14-16 mL (10% NH4Cl); in the spinning coagulation bath, sulfuric acid concentration of 75-95 g / L, sodium sulfate concentration of 135-180 g / L, zinc sulfate concentration of 55-85 g / L, temperature of 30-45℃, and fiber draw ratio of 110-120%. This range of process parameters was used as a trial production process, as illustrated in the following application example.

[0080] Application examples

[0081] Application Examples 1-4

[0082] The process parameters for the ultra-high wet modulus variable modal fibers used in Examples 1-4 are shown in Table 5, and the remaining steps are the same as in Example 1.

[0083] Table 5 Process parameters for application examples 1-4

[0084]

[0085] Application Example 5

[0086] The ultra-high wet modulus modal fiber in Application Example 5 differs from Application Example 3 in that the pulp used is bamboo pulp, while the other steps are the same as in Application Example 3.

[0087] Performance testing of Application Examples 1-5

[0088] High wet modulus variation modal fibers were prepared according to the preparation process of Application Examples 1-5, and then tested according to the above-mentioned testing methods. The test results are shown in Tables 6-8.

[0089] Among them, the length deviation rate, extra-long fiber rate, and double-length fiber content are all in accordance with the provisions of GB / T 14336;

[0090] The residual sulfur content shall be determined in accordance with the provisions of FZ / T 50014;

[0091] Defects shall be inspected in accordance with the provisions of GB / T 14339;

[0092] Whiteness shall be determined in accordance with the provisions of FZ / T 50013;

[0093] The oil content shall be determined in accordance with the provisions of GB / T 6504.

[0094] Table 6 shows the detection results of application examples 1-5.

[0095]

[0096] As can be seen from the test data of Application Examples 1-5 and Table 6, the wet modulus of the modal fibers prepared in this application is above 15.2 cN / dtex, the dry breaking strength is above 3.31 cN / dtex, and the hook strength is above 0.72 cN / dtex. This indicates that the modal fibers prepared in this application have achieved excellent wet modulus performance and high hook strength, which greatly improves the performance of modal fibers and expands the application prospects of modal fibers.

[0097] Table 7 Detection results of Application Example 3

[0098]

[0099]

[0100] As can be seen from the test data in Application Example 3 and Table 7, the various properties of the Modal fiber prepared in this application meet the superior grade indicators in the textile industry standard "Modal Fiber" and also meet the various indicators of BISFA Modal fiber.

[0101] Table 8 Comparison of Main Technical Indicators of Products

[0102]

[0103] As shown in Table 8, compared with leading international and domestic modal fiber products and international modal fiber standards, the wet modulus of the modal fiber prepared in this application exceeds that of leading international and domestic products by 29.2%, exceeds the international standard value by 83.4%, and exceeds the current textile industry standard value by 61%. The fiber hook strength is also superior to leading domestic and foreign products, and other performance standards meet the current textile industry standards.

[0104] The proposed high wet modulus modal fiber product will sell for over 10,000 RMB / ton more than ordinary viscose staple fiber, while increasing production costs by approximately 4,000 RMB / ton, resulting in a net profit of approximately 6,000 RMB / ton. Based on a 10% upgrade of domestic viscose staple fiber production capacity (5 million tons), this would generate an additional 3 billion RMB in profit annually, demonstrating significant economic benefits. This application's findings can break the control of some domestic and international viscose fiber manufacturers over high-end modal fiber production technology, promoting the upgrading and transformation of viscose fiber production enterprises.

[0105] The embodiments described above are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A preparation process for a modal fiber with ultra-high wet modulus variation, characterized in that: It includes the following steps: alkalization of pulp, aging of pulp cellulose, xanthation and dissolution of pulp cellulose, filtration of viscose, maturation of viscose, degassing of viscose, treatment of spinning solution, preparation of nascent filaments, drawing of nascent filaments, desulfurization of fibers, bleaching of fibers, washing of fibers, oiling of fibers, and drying of fibers. The preparation process includes the following parameters: the degree of polymerization of alkalized cellulose after aging is 400-600; the mass percentage of carbon disulfide added to methyl cellulose is 40-48%; the viscose aging degree is 14-16 mL (10% NH4Cl); in the spinning coagulation bath, the sulfuric acid concentration is 75-95 g / L, the sodium sulfate concentration is 135-180 g / L, the zinc sulfate concentration is 55-85 g / L, the coagulation bath temperature is 30-45℃, and the fiber draw ratio is 110-120%. The pulp is wood pulp or bamboo pulp, and the average degree of polymerization of the pulp is >600, wherein the methyl cellulose content is >92%; The alkalization step of the pulp is as follows: The pulp was soaked in a NaOH solution with a concentration of 180-250 g / L, and a penetrant was added. The penetrant accounted for 0.05-5% of the mass percentage of methyl cellulose in the pulp. The reaction time was 40-60 min, the reaction temperature was 30-50℃, and the bath ratio was 1:(3-6). The xanthation and dissolution of the pulp cellulose are as follows: A dry xanthation process is adopted, with an initial xanthation temperature of 25-30℃. The xanthated cellulose sulfonate is dissolved in a NaOH solution with a concentration of 15-20 g / L at a temperature of 0-4℃. The volume ratio of cellulose sulfonate to NaOH solution is 1:(3-5). The obtained cellulose xanthate solution is ground to obtain a viscose. The processing steps of the spinning solution include the following: Add a composite modifier to the spinning solution at a mass of 0.5-4% of the mass of methyl cellulose in the viscose; then add a defoamer at a volume of 0.02-0.1% of the spinning solution. The preparation steps of the nascent filaments include the following: The treated spinning solution is solidified in a spinning coagulation bath. The coagulation bath consists of H2SO4, ZnSO4, Na2SO4, coagulation bath additives and water. The concentration of the coagulation bath additives is 0.2-0.7 g / L, and the immersion time of the filaments in the coagulation bath is 1-2 seconds. In the preparation step of the nascent filament, the spinning speed is 25-40 m / min.

2. A modal fiber with ultra-high wet modulus variation, characterized in that, The ultra-high wet modulus variable modal fiber is prepared by the preparation process of ultra-high wet modulus variable modal fiber as described in claim 1.

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