An aluminosilicate flame-retardant regenerated cellulose fiber and its preparation method

Abstract

The present invention provides an aluminosilicate flame-retardant regenerated cellulose fiber and a preparation method thereof. The cellulose content in the fiber is 60-80 wt%, the SiO2 content is 20-35 wt%, and the Al2O3 content is 0-5 wt%. By reducing the temperature of the coagulation bath, reducing the contents of sulfuric acid and sodium sulfate in the coagulation bath, increasing the content of zinc sulfate, and delaying the fiber forming speed, more zinc cellulose sulfonate with a cross-linked structure can be generated by the reaction of zinc sulfate and sodium cellulose sulfonate, laying a foundation for the two-bath cross-linking forming; reducing the draw in the coagulation bath, preventing the breakage of the incompletely formed tow, and ensuring the spinnability of the fiber. In the second bath, Al 3+ undergoes a cross-linking and curing reaction with silicic acid and polysilicic acid in the gel state in the incompletely formed tow to form an aluminosilicate network structure penetrating through the cellulose macromolecules. At the same time, the incompletely formed nascent fiber tow is solidified and formed by sulfuric acid in the second bath, which can improve the strength of the fiber to a certain extent.

Description

Technical Field

[0001] The present invention belongs to the field of cellulose fibers, and particularly relates to an aluminosilicate flame-retardant regenerated cellulose fiber and a preparation method thereof. Background Art

[0002] Regenerated cellulose fiber is the second largest fiber variety in chemical fibers. It has the essence of cotton and the quality of silk. It originates from nature and is superior to nature. It is an important textile raw material and is widely used in the textile industry. However, the flammability of cellulose fibers poses a major hidden danger to people's lives and property safety, and to a certain extent restricts its application fields. The flame-retardant research of cellulose fibers has always been one of the key points of research and development. Currently, the flame-retardant fiber preparation technologies generally include three types: blending flame retardancy, graft copolymerization flame retardancy, and post-finishing flame retardancy. The currently industrialized products mainly adopt the method of adding and blending, which can endow the fibers with relatively durable flame-retardant properties. However, for the flame-retardant viscose fibers produced by the blending technology, there are problems such as a large amount of flame retardant added, loss of flame retardant during fiber production or use, decline in the mechanical properties of the flame-retardant fibers, and reduction in the wearing properties of the fibers. The "863" project of the state, "Research on New Flame-Retardant and Anti-Melting Fiber Materials and Textiles", undertaken by Qingdao University and Shandong Hailong, realized the industrial production of inorganic silicon-based flame-retardant viscose fibers and was promoted and applied in the non-woven field. However, the problem of loss of flame retardant during the dyeing and finishing and washing processes of fiber fabrics has always affected its application in the textile and clothing fields.

[0003] Patent CN200310117767.4 discloses that the precursor of SiO2, sodium silicate or potassium silicate, is added to the viscose solution to produce a composite material of silicon dioxide / cellulose; Patent CN102605452A discloses a preparation method of flame-retardant silicate fibers. To improve the loss of SiO2 in the coagulation bath forming process of the blend solution of the precursor of SiO2 and viscose, the control index of SiO2 is increased in the coagulation bath composition. Patent CN1847476A discloses a process method of inorganic silicon-based flame-retardant viscose fibers. To improve the flame-retardant and finishing resistance performance of inorganic silicon-based flame-retardant viscose fibers, a crosslinking treatment is added in the refining process. Using meta-aluminate, crosslinking treatment is carried out during the desulfurization of inorganic flame-retardant viscose fibers. Under high-temperature alkaline conditions, the silicic acid on the fibers dissolves and reacts with Al 3+ to form stable aluminosilicate on the fiber surface, improving the flame-retardant and finishing resistance performance of the fibers. While the refining crosslinking treatment improves the adhesion firmness of the flame retardant to the fibers, it also causes a certain amount of loss of the flame retardant SiO2, and there is also an uneven crosslinking treatment problem between the upper and lower cotton layers of the refining machine. This treatment technology is not suitable for industrial continuous production.

[0004] Wang Ke proposed in the paper "Research and Development of High Temperature Resistant and Flame Retardant Silicon-Aluminum-Cellulose Blended Viscose Fiber" that a certain amount of sodium aluminate was added to the mixed solution of sodium silicate and viscose by in-spinning injection. At the same time, aluminum sulfate component was added to the coagulation bath during the forming process. It was also mentioned that the addition of sodium aluminate had an impact on the filtration and spinnability of the flame retardant viscose solution. This method would cause the reaction between sodium silicate in the sodium aluminate and viscose mixture, resulting in the risk of gelation. Al 3+ in the coagulation bath would react with silicic acid, aggregate and precipitate, and did not have the feasibility of continuous production. Based on the process of patent CN102605452A, the present invention adjusted the spinning and forming process, delayed the forming speed of the flame retardant fiber bundle in the coagulation bath, and added the two-bath crosslinking forming technology for the flame retardant fiber bundle to realize the development and stable production of the flame retardant and finishing-resistant aluminosilicate flame retardant regenerated cellulose fiber. Summary of the Invention

[0005] In order to solve the problem of flame retardant loss in inorganic silicon-based flame retardant viscose fibers in the prior art, the present invention provides an aluminosilicate flame retardant regenerated cellulose fiber and its preparation method. By adjusting the solidification and forming conditions and adopting the two-bath crosslinking forming technology, a flame retardant and finishing-resistant aluminosilicate flame retardant regenerated cellulose fiber is prepared.

[0006] In order to solve the above technical problems, one of the purposes of the present invention is to provide an aluminosilicate flame retardant regenerated cellulose fiber, wherein the cellulose content in the fiber is 60-80 wt%, the SiO2 content is 20-35 wt%, and the Al2O3 content is 0-5 wt%.

[0007] Another purpose of the present invention is to provide a preparation method of an aluminosilicate flame retardant regenerated cellulose fiber, and the preparation method includes the following steps:

[0008] S1. Preparation of flame retardant viscose spinning solution

[0009] Using cellulose pulp as the raw material, cellulose xanthate is prepared through steps including impregnation, pressing, pulverization, aging, and xanthation; the cellulose xanthate is dissolved in a 4-8% sodium hydroxide solution, and then the precursor solution of the silicon-based flame retardant is added and dissolved, and the flame retardant viscose spinning solution is obtained through filtration, aging, and defoaming.

[0010] Preferably, the content of alpha cellulose in the flame retardant viscose spinning solution is 6.2-7.8 wt%, and the content of the active ingredient SiO2 of the silicon-based flame retardant relative to alpha cellulose is 30-50 wt%; the content of NaOH in the flame retardant viscose spinning solution is 6.0-8.2 wt%.

[0011] Preferably, the precursor of the silicon-based flame retardant is sodium silicate.

[0012] S2. Coagulation bath treatment

[0013] The flame-retardant viscose spinning solution is solidified in a coagulation bath to obtain a nascent fiber bundle.

[0014] Preferably, the coagulation bath includes H2SO4, ZnSO4, Na2SO4 and a silicon-based flame retardant.

[0015] Preferably, the contents of the components in the coagulation bath are as follows: 60 - 80 g / L of H2SO4, 50 - 60 g / L of ZnSO4, 220 - 250 g / L of Na2SO4, and the effective content of SiO2 in the silicon-based flame retardant is 0.1 - 1.2 g / L.

[0016] The temperature of the coagulation bath is controlled at 35 - 40 °C, the time is 0.5 - 2.0 s, and the draw ratio in the coagulation bath is controlled at 10 - 50%.

[0017] S3. Crosslinking and forming in the second bath

[0018] The nascent fiber bundle coming out of the coagulation bath undergoes inter-disk drawing and enters the second bath for crosslinking and forming. The time in the second bath is 20 - 50 s.

[0019] Preferably, the inter-disk draw ratio is controlled at 30 - 60%.

[0020] Preferably, the second bath is an H2SO4 solution containing an aluminum salt, and the aluminum salt is Al2SO4 or AlCl3 or a mixture of Al2SO4 and AlCl3; the contents of the components in the second bath are as follows: 20 - 60 g / L of H2SO4, and the concentration of Al 3+ is 0.5 - 5 g / L; the temperature of the second bath is controlled at 55 - 90 °C.

[0021] S4. Refining and drying

[0022] The fibers after crosslinking and forming in the second bath are washed, cut, and enter the refining process. After washing, desulfurization, bleaching, oiling, drying, and packing, the finished product of aluminosilicate flame-retardant regenerated cellulose fiber is obtained.

[0023] Due to the adoption of the above technical solutions, the technical effects achieved by the present invention are as follows:

[0024] 1. The aluminosilicate flame-retardant regenerated cellulose fiber prepared by the present invention has excellent mechanical properties, and the dry breaking strength is as high as 2.05 - 2.5 cN / dtex, and the spinnability is stronger.

[0025] 2. The present invention delays the fiber forming speed by reducing the temperature of the coagulation bath, reducing the contents of sulfuric acid and sodium sulfate in the coagulation bath, increasing the content of zinc sulfate, and at the same time, zinc sulfate and sodium cellulose sulfonate can react to form more zinc cellulose sulfonate with a crosslinked structure, laying a foundation for crosslinking and forming in the second bath; reducing the draw ratio in the coagulation bath to prevent the breakage of incompletely formed fiber bundles and ensuring the spinnability of the fibers. In the second bath, Al 3+Crosslinking and curing reaction with silicic acid and polysilicic acid in the gel state in the incompletely formed tow to generate an aluminosilicate network structure penetrating the cellulose macromolecules. At the same time, the incompletely formed primary fiber tow is solidified and formed by sulfuric acid in the second bath, which can improve the strength of the fiber to a certain extent.

[0026] 3. The present invention uses a two-bath crosslinking and curing method to prepare aluminosilicate flame-retardant regenerated cellulose fibers, reducing the loss of flame retardants during the fiber preparation process, making the flame retardants more stable and uniform in the fibers, ensuring the flame-retardant and wash-resistant properties of the fibers, with simple operation and low cost, and is suitable for industrial production. Detailed implementation manners

[0027] The following further elaborates the present invention in conjunction with specific embodiments.

[0028] Example 1

[0029] S1. Preparation of flame-retardant viscose spinning solution

[0030] Using wood pulp as raw material, cellulose xanthate is prepared through steps including impregnation, pressing, pulverization, aging, and xanthation; the cellulose xanthate is dissolved in a 6% sodium hydroxide solution, and then a precursor solution of a silicon-based flame retardant is added, and after filtration, aging, and degassing, a flame-retardant viscose spinning solution is obtained.

[0031] The content of alpha-cellulose in the flame-retardant viscose spinning solution is 6.2 wt%, the content of the active ingredient SiO2 of the silicon-based flame retardant relative to alpha-cellulose is 30 wt%; the content of NaOH in the flame-retardant viscose spinning solution is 6.0 wt%.

[0032] The precursor of the silicon-based flame retardant is sodium silicate.

[0033] S2. Treatment of coagulation bath

[0034] The flame-retardant viscose spinning solution is metered by a metering pump and sprayed into the coagulation bath through a spinneret for coagulation to obtain a primary fiber tow.

[0035] The coagulation bath includes H2SO4, ZnSO4, Na2SO4, and a silicon-based flame retardant.

[0036] The contents of each component in the coagulation bath are: H2SO4 is 65 g / L, ZnSO4 is 60 g / L, Na2SO4 is 230 g / L, and the effective content of SiO2 of the silicon-based flame retardant is 1.2 g / L.

[0037] The temperature of the coagulation bath is controlled at 38°C, the time is 0.8 s, and the draw ratio in the coagulation bath is controlled at 26%.

[0038] S3. Two-bath crosslinking and forming

[0039] The nascent fiber tow emerging from the coagulation bath undergoes inter-disk stretching and then enters the second bath for crosslinking and shaping. The time in the second bath is 45S.

[0040] The inter-disk stretching is controlled at 30%.

[0041] The second bath is an H2SO4 solution containing Al2SO4; the contents of each component in the second bath are: 56g / L of H2SO4, and 3+ 2.5g / L of Al; the temperature of the second bath is controlled at 82°C.

[0042] S4, refining and drying

[0043] The fiber after crosslinking and shaping in the second bath is washed, cut, and then enters the refining process. After washing, desulfurization, bleaching, oiling, drying, and packing, the finished product of aluminosilicate flame-retardant regenerated cellulose fiber is obtained; the fineness of the obtained fiber is 3.33 dtex, the dry breaking strength is 2.5 cN / dtex, the burning residue is 31.9% (including 28.6% of SiO2 and 3.3% of Al2O3), and the loss rate of the silicon-based flame retardant after 50 times of washing is 2.06%.

[0044] Example 2

[0045] S1. Preparation of flame-retardant viscose spinning solution

[0046] Using cotton pulp as the raw material, cellulose xanthate is prepared through steps including impregnation, pressing, pulverization, aging, and xanthation; the cellulose xanthate is dissolved in a 4% sodium hydroxide solution, and then the precursor solution of the silicon-based flame retardant is added, and after filtration, aging, and degassing, the flame-retardant viscose spinning solution is obtained.

[0047] The content of alpha cellulose in the flame-retardant viscose spinning solution is 7.8 wt%, the content of the active ingredient SiO2 of the silicon-based flame retardant relative to alpha cellulose is 42.5 wt%; the content of NaOH in the flame-retardant viscose spinning solution is 8.2 wt%.

[0048] The precursor of the silicon-based flame retardant is sodium silicate.

[0049] S2. Coagulation bath treatment

[0050] The flame-retardant viscose spinning solution is metered by a metering pump and sprayed into the coagulation bath through a spinneret for coagulation to obtain a nascent fiber tow.

[0051] The coagulation bath includes H2SO4, ZnSO4, Na2SO4, and a silicon-based flame retardant.

[0052] The contents of each component in the coagulation bath are: 75g / L of H2SO4, 50g / L of ZnSO4, 220g / L of Na2SO4, and the effective content of SiO2 of the silicon-based flame retardant is 0.1g / L.

[0053] The temperature of the coagulation bath is controlled at 36°C, the time is 0.5S, and the draw ratio in the coagulation bath is controlled at 35%.

[0054] S3. Crosslinking and forming in the second bath

[0055] The nascent fiber bundle coming out of the coagulation bath undergoes inter-disk drawing and enters the second bath for crosslinking and forming. The time in the second bath is 35S.

[0056] The inter-disk draw ratio is controlled at 45%.

[0057] The second bath is an H2SO4 solution containing AlCl3; the content of each component in the second bath is: 45g / L of H2SO4, Al 3+ The concentration is 5g / L; the temperature of the second bath is controlled at 70°C.

[0058] S4. Refining and drying

[0059] The fiber after crosslinking and forming in the second bath is washed, cut, and enters the refining process. After washing, desulfurization, bleaching, oiling, drying, and packing, the finished product of aluminosilicate flame-retardant regenerated cellulose fiber is obtained; the fineness of the obtained fiber is 4.89 dtex, the dry breaking strength is 2.34 cN / dtex, the burning residue is 33.6% (including 29.4% of SiO2 and 4.2% of Al2O3), and the loss rate of the silicon-based flame retardant after 50 washes is 2.73%.

[0060] Example 3

[0061] S1. Preparation of flame-retardant viscose spinning solution

[0062] Using cotton pulp and wood pulp with a mass ratio of 1:1 as raw materials, cellulose xanthate is prepared through steps including impregnation, pressing, crushing, aging, and xanthation; the cellulose xanthate is dissolved in an 8% sodium hydroxide solution, and then the precursor solution of the silicon-based flame retardant is added, and the flame-retardant viscose spinning solution is obtained through filtration, aging, and degassing.

[0063] The content of alpha-cellulose in the flame-retardant viscose spinning solution is 7.2 wt%, the content of the effective component SiO2 of the silicon-based flame retardant relative to alpha-cellulose is 50 wt%; the content of NaOH in the flame-retardant viscose spinning solution is 7.8 wt%.

[0064] The precursor of the silicon-based flame retardant is sodium silicate.

[0065] S2. Coagulation bath treatment

[0066] The flame-retardant viscose spinning solution is metered by a metering pump and sprayed into the coagulation bath through a spinneret for coagulation to obtain a nascent fiber bundle.

[0067] The coagulation bath includes H2SO4, ZnSO4, Na2SO4, and a silicon-based flame retardant.

[0068] The contents of each component in the coagulation bath are as follows: H2SO4 is 80 g / L, ZnSO4 is 58 g / L, Na2SO4 is 250 g / L, and the effective content of SiO2 in the silicon-based flame retardant is 0.86 g / L.

[0069] The temperature of the coagulation bath is controlled at 35 °C, the time is 2.0 s, and the draw ratio in the coagulation bath is controlled at 10%.

[0070] S3. Crosslinking and forming in the second bath

[0071] The nascent fiber bundle coming out of the coagulation bath undergoes inter-disk drawing and enters the second bath for crosslinking and forming. The time in the second bath is 50 s.

[0072] The inter-disk draw ratio is controlled at 60%.

[0073] The second bath is an H2SO4 solution containing AlCl3; the contents of each component in the second bath are as follows: H2SO4 is 60 g / L, and the concentration of Al 3+ is 0.5 g / L; the temperature of the second bath is controlled at 55 °C.

[0074] S4. Refining and drying

[0075] The fiber after crosslinking and forming in the second bath is washed, cut, and enters the refining process. After washing, desulfurization, bleaching, oiling, drying, and packing, the finished product of aluminum silicate flame retardant regenerated cellulose fiber is obtained. The fineness of the obtained fiber is 4.78 dtex, the dry breaking strength is 2.05 cN / dtex, the burning residue is 34.8% (including 33.8% of SiO2 and 1.0% of Al2O3), and the loss rate of the silicon-based flame retardant after 50 times of washing is 2.27%.

[0076] Example 4

[0077] S1. Preparation of flame retardant viscose spinning solution

[0078] Using cotton pulp and wood pulp with a mass ratio of 1:3 as raw materials, cellulose xanthate is prepared through steps including impregnation, pressing, crushing, aging, and yellowing; the cellulose xanthate is dissolved in a 6% sodium hydroxide solution, and then the precursor solution of the silicon-based flame retardant is added. After filtration, aging, and degassing, the flame retardant viscose spinning solution is obtained.

[0079] The content of alpha cellulose in the flame retardant viscose spinning solution is 7.4 wt%, and the content of the effective component SiO2 of the silicon-based flame retardant relative to alpha cellulose is 46 wt%; the content of NaOH in the flame retardant viscose spinning solution is 7.2 wt%.

[0080] The precursor of the silicon-based flame retardant is sodium silicate.

[0081] S2. Coagulation bath treatment

[0082] The flame-retardant viscose spinning solution is metered by a metering pump and sprayed into a coagulation bath through a spinneret for coagulation to obtain a nascent fiber bundle.

[0083] The coagulation bath includes H2SO4, ZnSO4, Na2SO4 and a silicon-based flame retardant.

[0084] The contents of each component in the coagulation bath are: 60 g / L of H2SO4, 52 g / L of ZnSO4, 240 g / L of Na2SO4, and the effective content of SiO2 in the silicon-based flame retardant is 0.5 g / L.

[0085] The temperature of the coagulation bath is controlled at 40 °C, the time is 1.2 s, and the draw ratio in the coagulation bath is controlled at 50%.

[0086] S3. Crosslinking and forming in the second bath

[0087] The nascent fiber bundle coming out of the coagulation bath undergoes inter-disk drawing and enters the second bath for crosslinking and forming, and the time in the second bath is 25 s.

[0088] The inter-disk draw ratio is controlled at 35%.

[0089] The second bath is an H2SO4 solution containing Al2SO4; the contents of each component in the second bath are: 20 g / L of H2SO4, and the concentration of Al 3+ is 3 g / L; the temperature of the second bath is controlled at 65 °C.

[0090] S4. Refining and drying

[0091] The fiber after crosslinking and forming in the second bath is washed, cut and enters the refining process. After washing, desulfurization, bleaching, oiling, drying and packing, the finished product of aluminosilicate flame-retardant regenerated cellulose fiber is obtained. The fineness of the prepared fiber is 5.56 dtex, the dry breaking strength is 2.18 cN / dtex, the burning residue is 33.4% (including 30.6% of SiO2 and 2.8% of Al2O3), and the loss rate of the silicon-based flame retardant after 50 times of washing is 2.3%.

[0092] Comparative example 1

[0093] Select the representative Example 1, remove Al2SO4 in the second bath, and the rest are the same as in Example 1, as Comparative example 1. The fineness of the prepared fiber is 3.5 dtex, the dry breaking strength is 1.98 cN / dtex, the burning residue is 27.4%, and the loss rate of the silicon-based flame retardant after 50 times of washing is 62.7%, indicating that crosslinking and forming in the second bath significantly improves the washing resistance of the flame-retardant fiber.

[0094] Comparative example 2

[0095] The flame-retardant fiber was prepared according to the process of Example 1 in Patent CN102605452A. As Comparative Example 2, the loss rate of the silicon-based flame retardant after 50 times of washing was tested to be 74%, which was higher than that of Comparative Example 1. This was because in the present invention, the coagulation bath delayed the forming process and the second bath completed the forming process, so that the silicon-based flame retardant was more evenly distributed in the fiber; while in the process of Comparative Example 2, the flame retardant was directly added to the coagulation bath for one-time forming, and the uniformity of the silicon-based flame retardant in the fiber was poor, and the wash resistance was also worse.

[0096] Unless otherwise specified, the ratios described in the present invention are all mass ratios, and the percentages are all mass percentages; the raw materials are all commercially available.

[0097] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An aluminosilicate flame-retardant regenerated cellulose fiber, characterized in that, The cellulose content in the fiber is 60 - 80 wt%, the SiO2 content is 20 - 35 wt%, and the Al2O3 content is 0 - 5 wt%. The preparation method of the aluminosilicate flame - retardant regenerated cellulose fiber includes the preparation of flame - retardant viscose spinning solution, coagulation bath treatment, two - bath cross - linking forming, and refining and drying. The coagulation bath treatment is to coagulate the flame - retardant viscose spinning solution in the coagulation bath to obtain a nascent fiber bundle. The coagulation bath includes H2SO4, ZnSO4, Na2SO4 and a silicon - based flame retardant. The contents of each component in the coagulation bath are: H2SO4 is 60 - 80 g / L, ZnSO4 is 50 - 60 g / L, Na2SO4 is 220 - 250 g / L, and the effective content of SiO2 in the silicon - based flame retardant is 0.1 - 1.2 g / L. The temperature of the coagulation bath is controlled at 35 - 40 °C, the time is 0.5 - 2.0 s, and the draw ratio in the coagulation bath is controlled at 10 - 50%. The two - bath cross - linking forming is that the nascent fiber bundle coming out of the coagulation bath undergoes inter - bobbin drawing and then enters the two - bath cross - linking forming, and the two - bath time is 20 - 50 s. The inter - bobbin drawing is controlled at 30 - 60%. The two - bath is an H2SO4 solution containing an aluminum salt, and the aluminum salt is AlCl3. The content of each component in the second bath is as follows: H2SO4 is 20 to 60 g / L, and the concentration of Al 3+ is 0.5 to 5 g / L; the temperature of the second bath is controlled at 55 to 90 °C.

2. The aluminosilicate flame-retardant regenerated cellulose fiber according to claim 1, wherein, The preparation of the flame - retardant viscose spinning solution is as follows: using cellulose pulp as the raw material, cellulose xanthate is obtained through steps including impregnation, pressing, crushing, aging, and xanthation; the cellulose xanthate is dissolved in a 4 - 8% sodium hydroxide solution, and then the precursor solution of the silicon - based flame retardant is added, and after filtration, ripening, and degassing, the flame - retardant viscose spinning solution is obtained.

3. The aluminosilicate flame-retardant regenerated cellulose fiber according to claim 2, wherein, The content of alpha - cellulose in the flame - retardant viscose spinning solution is 6.2 - 7.8 wt%, the content of the effective component SiO2 in the silicon - based flame retardant relative to alpha - cellulose is 30 - 50 wt%; the content of NaOH in the flame - retardant viscose spinning solution is 6.0 - 8.2 wt%.

4. The aluminosilicate flame-retardant regenerated cellulose fiber according to claim 1, wherein, The refining and drying is that the fiber after two - bath cross - linking forming is washed, cut and then enters the refining process, and after washing, desulfurization, bleaching, oiling, drying, and packing, the finished product of aluminosilicate flame - retardant regenerated cellulose fiber is obtained.