Preparation method of polylactic acid fiber tow, polylactic acid fiber tow and application of polylactic acid fiber tow

Abstract

The invention relates to a preparation method of a polylactic acid fiber tow, the polylactic acid fiber tow and application of the polylactic acid fiber tow. The preparation method of the polylactic acid fiber tow comprises a fore-spinning step and a post-spinning step, the fore-spinning step comprises the steps of drying, melting, spinning and winding first polylactic acid slices and modifier master batches, and nascent fibers are obtained; the modifier master batch comprises a second polylactic acid slice and a modifier, and the modifier is selected from titanium dioxide; the post-spinning step comprises the steps that the nascent fibers are sequentially subjected to oil immersion, drafting, water bath and hot water ironing, intermediate fibers are obtained, and the temperature of hot water ironing treatment is 60-90 DEG C. Compared with a traditional tow production technology, a tension heat setting process does not need to be adopted, equipment investment and energy consumption are reduced, meanwhile, the tows are ironed with hot water before curling, the consistency and stability of the curling effect are improved, and the curling quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of polylactic acid spinning, and in particular to a preparation method of a polylactic acid fiber bundle, a polylactic acid fiber bundle and applications thereof. Background Art

[0002] At present, the main materials for cigarette filters are diacetate fiber tow and polypropylene fiber tow. Polypropylene is a completely crystalline polymer with a stable structure and no polar groups. The tow surface is smooth, the adsorption performance is poor, and the spicy taste is heavy. It can only be used in low-end cigarettes. With the improvement of people's living standards and health and environmental protection requirements, it has basically withdrawn from the market in my country and is mainly used in Southeast Asian cigarette markets such as Vietnam and Laos.

[0003] Diacetate fiber tow is a filter material with good performance and widely used at home and abroad. The raw materials come from high-quality wood (such as eucalyptus) grown for many years. Dry solution spinning is used to produce tows of different specifications. The domestic production generally adopts the technology of developed countries such as Celanese, Eastman and Daicel of Japan. The polymer chain of diacetate fiber tow contains strong polar groups such as -OH, and the surface of the tow has micropores. Therefore, diacetate fiber tow has adsorption and filtration effects on harmful components of smoke. Triacetin is added for bonding during the molding process, and the filter rod meets the requirements of hardness, circumference and suction resistance. However, the raw material of diacetate fiber tow is high-quality wood grown for many years, which mainly relies on imports. At the same time, acetone is required as a solvent in the production of wood pulp, esterification of cellulose and spinning of diacetate fiber tow. The production process is more dangerous and seriously pollutes the environment, resulting in high production costs. In addition, compared with polylactic acid fiber, its biodegradability is poor, and it takes several years to degrade. It will cause certain pollution to the environment after being discarded.

[0004] Polylactic acid is a biopolymer material made from renewable plant resources (corn, cassava) or straw cellulose (corn cobs and plant straw, etc.) using modern biofermentation technology to make lactic acid, which is then polymerized. It has good biodegradability and recyclability, is safe and environmentally friendly, and meets the sustainable development requirements of the domestic and international communities. Polylactic acid has good processability, uses melt spinning, has low energy consumption, and does not cause any pollution to the environment. The surface of polylactic acid fiber has discontinuous horizontal stripes and grooves, and contains polar groups (ester groups) in the molecules. It has a strong adsorption and filtration effect on harmful components in smoke, and is a suitable material for cigarette filters. Compared with the development and application of textile materials, the development of polylactic acid fiber tow as a filter material for cigarettes is relatively slow in China, and there are few reports on the large-scale application of polylactic acid fiber tow in cigarette filter materials. Therefore, the development of polylactic acid fiber tow, especially the tow products used in new low-temperature cigarette filter rods, is of great significance. Summary of the invention

[0005] In order to solve the above technical problems existing in the prior art, the present invention provides a method for preparing a polylactic acid fiber bundle.

[0006] In a first aspect, the preparation method of the polylactic acid fiber bundle provided by the present invention comprises a pre-spinning step and a post-spinning step, wherein the pre-spinning step comprises drying, melting, spinning and winding the first polylactic acid slice and the modifier masterbatch to obtain the spun fiber; wherein the modifier masterbatch comprises the second polylactic acid slice and the modifier, and the modifier is selected from titanium dioxide;

[0007] The post-spinning step includes sequentially subjecting the primary fibers to oil immersion, drafting, water bath treatment and hot water ironing treatment to obtain intermediate fibers, wherein the temperature of the hot water ironing treatment is 60°C-90°C.

[0008] In some embodiments, the post-spinning step further comprises sequentially subjecting the intermediate fibers to curling, relaxation heat setting, and packaging to obtain the polylactic acid fiber tow.

[0009] In some embodiments, the temperature of the hot water ironing treatment is 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or any value therebetween. The present invention performs hot water ironing on the tow before curling, especially hot water ironing at a specific temperature, which can well improve the consistency and stability of the curling effect and ensure the curling quality. In some embodiments, the temperature of the hot water ironing treatment is 70°C-80°C.

[0010] In some embodiments, based on the mass of the modifier masterbatch, the mass content of the modifier is 20%-55%. In some embodiments, the mass content of the modifier is 22%, 25%, 27%, 30%, 33%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 46%, 48%, 50%, 53% or any value therebetween. In some embodiments, the mass content of the modifier is 35%-45%.

[0011] In some embodiments, based on the mass content of the first polylactic acid slice, the mass content of the modifier masterbatch is 0.4%-0.8%. In some embodiments, the mass content of the modifier masterbatch is 0.43%, 0.45%, 0.47%, 0.51%, 0.53%, 0.55%, 0.57%, 0.59%, 0.60%, 0.61%, 0.63%, 0.65%, 0.67%, 0.69%, 0.71%, 0.73%, 0.75%, 0.77% or any value therebetween. In some embodiments, the mass content of the modifier masterbatch is 0.5%-0.7%.

[0012] In some embodiments, in the pre-spinning step, the moisture content of the first polylactic acid slice after drying is less than 0.05‰. In some embodiments, in the pre-spinning step, the moisture content of the modifier masterbatch after drying is less than 0.05‰.

[0013] In some embodiments, the temperature of the first polylactic acid chip drying process is 90° C.-110° C., for example, 93° C., 95° C., 97° C., 99° C., 100° C., 103° C., 105° C. or 107° C. In some embodiments, the temperature of the first polylactic acid chip drying process is 95° C.-105° C.

[0014] In some embodiments, the first polylactic acid slice is dried for 3 hours to 12 hours, such as 4 hours, 6 hours, 8 hours or 10 hours. In some embodiments, the first polylactic acid slice is dried for 5 hours to 9 hours.

[0015] In some embodiments, the temperature of the drying process of the modifier masterbatch is 90°C-110°C, for example, 93°C, 95°C, 97°C, 99°C, 100°C, 103°C, 105°C or 107°C. In some embodiments, the temperature of the drying process of the modifier masterbatch is 95°C-103°C.

[0016] In some embodiments, the time for drying the modifier masterbatch is greater than or equal to 24 hours. In some embodiments, the time for drying the modifier masterbatch is 25 hours to 40 hours.

[0017] In some embodiments, in the pre-spinning step, the melt treatment is carried out in a screw extruder. In some embodiments, during the melt treatment, the screw temperature is 220°C-250°C, for example, 223°C, 225°C, 227°C, 230°C, 233°C, 235°C, 237°C, 240°C, 243°C, 245°C or 247°C. In some embodiments, the screw temperature is 225°C-240°C.

[0018] In some embodiments, in the pre-spinning step, the spinning process is performed in a spinning beam.

[0019] In some embodiments, the spinning process includes filtering and spinning the melt after the melt treatment. In some embodiments, during the spinning process, the spinning manifold temperature is 210°C-240°C, for example, 213°C, 215°C, 217°C, 220°C, 223°C, 225°C, 227°C, 230°C, 233°C, 235°C or 237°C. In some embodiments, the spinning manifold temperature is 215°C-230°C.

[0020] In some embodiments, the number of holes of the spinneret used for spinning is 180-800 holes, for example, 200 holes, 250 holes, 300 holes, 350 holes, 400 holes, 450 holes, 500 holes, 550 holes, 600 holes, 650 holes, 700 holes or 750 holes.

[0021] In some embodiments, the spinneret hole shape is Y-shaped or circular.

[0022] In some embodiments, the winding speed of the winding process is 500m / min-1200m / min, for example, 600m / min, 700m / min, 800m / min, 900m / min, 1000m / min or 1100m / min. In some embodiments, the winding speed of the winding process is 600m / min-1000m / min.

[0023] In some embodiments, in the post-spinning step, the spun fibers are subjected to a bundling treatment before being subjected to an oil soaking treatment.

[0024] In some embodiments, in the post-spinning step, the temperature of the oil immersion treatment is less than or equal to 40° C. In some embodiments, in the post-spinning step, the temperature of the oil immersion treatment is 25° C.-35° C.

[0025] In some embodiments, in the post-spinning step, the drafting treatment is a waterbath drafting treatment. In some embodiments, the temperature during the drafting treatment is 60°C-80°C, for example, 65°C, 67°C, 70°C, 73°C, 75°C or 77°C. In some embodiments, the temperature during the drafting treatment is 62°C-75°C.

[0026] In some embodiments, the drafting ratio is 2.4 to 3.0 times.

[0027] In some embodiments, in the post-spinning step, the water bath treatment temperature is 70° C.-90° C., for example, 73° C., 75° C., 77° C., 79° C., 83° C., 85° C. or 87° C. In some embodiments, in the post-spinning step, the water bath treatment temperature is 75° C.-85° C.

[0028] In some embodiments, in the post-spinning step, during the crimping process, the crimping wheel diameter is 50 mm-100 mm, for example, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm or 95 mm. In some embodiments, the crimping wheel diameter is 60 mm-80 mm.

[0029] In some embodiments, in the post-spinning step, during the crimping process, the crimping wheel width is 15 mm-30 mm, for example, 17 mm, 20 mm, 23 mm, 25 mm or 27 mm. In some embodiments, the crimping wheel width is 20 mm-28 mm.

[0030] In some embodiments, in the post-spinning step, the temperature of the relaxation heat setting treatment is 45°C-60°C, for example, 47°C, 50°C, 53°C, 55°C or 57°C. In some embodiments, the temperature of the relaxation heat setting treatment is 50°C-55°C.

[0031] In some embodiments, in the post-spinning step, the time of the relaxation heat setting treatment is 5 min-20 min, for example, 7 min, 9 min, 10 min, 13 min, 15 min or 17 min. In some embodiments, the time of the relaxation heat setting treatment is 10 min-15 min.

[0032] In some embodiments, the method for preparing the polylactic acid fiber tow comprises the following specific steps:

[0033] The pre-spinning step includes drying the polylactic acid slices and the modifier masterbatch respectively, and then simultaneously inputting them into the screw for melting and the spinning box for filtering and spinning through the components, and then winding and dropping into the barrel to obtain the primary fiber;

[0034] The post-spinning step includes the steps of oil soaking, water bath drawing, hot water bath, hot water ironing, curling, relaxation and heat setting, and packaging to obtain the finished polylactic acid fiber bundle after the primary fiber is bundled.

[0035] In a second aspect, the present invention provides a polylactic acid fiber bundle prepared by the preparation method described in the first aspect.

[0036] In some embodiments, the single-filament linear density of the polylactic acid fiber tow is 5.56 dtex-31.11 dtex, and the overall linear density of the tow is 2.22 ktex-4.44 ktex.

[0037] In some embodiments, the linear density variation coefficient of the polylactic acid fiber tow is ≤0.6%.

[0038] In a third aspect, the present invention provides the use of the polylactic acid fiber bundle described in the second aspect in a cigarette filter rod.

[0039] The beneficial effects of the present invention are:

[0040] (1) The tow produced by the present invention can be directly applied to the production of filter rods for new low-temperature cigarettes without the need to apply adhesives such as triacetin, thereby reducing production processes and costs.

[0041] (2) Compared with the traditional tow production technology, the present invention does not need to adopt the tensile heat setting process, which reduces the equipment investment and energy consumption.

[0042] (3) Compared with the traditional yarn production technology, the present invention irons the yarn bundle with hot water before curling, which improves the consistency and stability of the curling effect and ensures the curling quality.

[0043] (4) The polylactic acid fiber tow produced by the present invention has no defects, and the coefficient of variation of linear density is ≤0.6%, which meets the standard requirements of diacetate fiber tow. DETAILED DESCRIPTION

[0044] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0045] Unless otherwise specified, all reagents and raw materials used in the present invention are commercially available products or products that can be prepared by known methods.

[0046] The polylactic acid slices used in the examples were purchased from Anhui Fengyuan Futailai Polylactic Acid Co., Ltd.

[0047] The linear density test adopts YC / T 169.1-2009 Determination of physical and chemical properties of tobacco tow Part 1: Linear density of tow and YC / T 169.2-2009 Determination of physical and chemical properties of tobacco tow Part 1: Linear density of single yarn.

[0048] Example 1

[0049] 1. Pre-spinning steps

[0050] Raw material drying: The polylactic acid chips were dried at 95°C for 9 hours; the modifier masterbatch (a blend of polylactic acid chips and titanium dioxide, in which the titanium dioxide content is 40%) was weighed according to 0.6% of the amount of polylactic acid chips and dried at 95°C for 30 hours. After drying, the moisture content of the polylactic acid chips was 0.03‰, and the moisture content of the modifier masterbatch was 0.045‰.

[0051] Screw melting and spinning box assembly filtering and spinning: The dried polylactic acid slices and modifier masterbatch are simultaneously transported to the screw extruder for heating and melting, and the melt is filtered and spun through the assembly in the spinning box to form primary fibers. The screw temperature during heating and melting is 235°C and the spinning box temperature is 226°C; the spinneret has 320 holes, and the spinneret hole shape is Y-shaped.

[0052] Winding and dropping into barrel: the nascent fiber is wound by a traction machine and a feeding machine and sent into a fiber barrel, and the winding speed is 1000m / min.

[0053] 2. Post-spinning steps

[0054] Bunching, oiling, drawing, water bathing, ironing: Bunching the nascent fibers obtained by spinning is followed by oiling, water bath drawing, hot water bathing, and hot water ironing to improve physical and mechanical properties and obtain better curling effects. The oiling temperature is 31°C; the water bath drawing temperature is 70°C, the drawing multiple is 2.75 times; the hot water bath temperature is 80°C; and the hot water ironing temperature is 75°C.

[0055] Crimping, relaxation heat setting, and packaging: the fibers after hot water ironing are sent to the crimping machine for crimping, and then dried in the relaxation heat setting machine and packaged to obtain a polylactic acid fiber tow with a single-filament linear density of 8.89 dtex and a total linear density of 2.22 ktex. The crimping wheel used for the crimping has a diameter of 80 mm and a width of 20 mm; the relaxation heat setting temperature is 52°C and the time is 12 minutes.

[0056] After testing, the yarn defects were 0, the coefficient of variation of linear density was 0.41%, the number of crimps was 28 / 25mm, the breaking strength was 18.4cN, the breaking elongation was 39.6%, and the moisture content was 0.18%.

[0057] Example 2

[0058] 1. Pre-spinning steps

[0059] Raw material drying: The polylactic acid chips were dried at 100°C for 7 hours; the modifier masterbatch (the titanium dioxide content in the masterbatch was 35%) was weighed according to 0.4% of the amount of polylactic acid chips and dried at 100°C for 27 hours. After drying, the moisture content of the polylactic acid chips was 0.028‰, and the moisture content of the modifier masterbatch was 0.042‰.

[0060] Screw melting and spinning box assembly filtering and spinning: The dried polylactic acid slices and modifier masterbatch are simultaneously transported to the screw extruder for heating and melting, and the melt is filtered and spun through the assembly in the spinning box to form primary fibers. The screw temperature during heating and melting is 240°C and the spinning box temperature is 230°C; the spinneret has 180 holes, and the spinneret hole shape is circular.

[0061] Winding and dropping into barrel: the raw fiber is wound by the traction machine and the feeding machine and sent into the wire barrel, and the winding speed is 700m / min.

[0062] 2. Post-spinning steps

[0063] Bunching, oiling, drawing, water bathing, ironing: Bunching the primary fibers obtained by spinning is followed by oiling, water bath drawing, hot water bathing, and hot water ironing in order to improve the physical and mechanical properties and obtain a better curling effect. The oiling temperature is 35°C; the water bath drawing temperature is 75°C, the drawing multiple is 2.5 times; the hot water bath temperature is 85°C; and the hot water ironing temperature is 80°C.

[0064] Crimping, relaxation heat setting, and packaging: the fibers after hot water ironing are sent to the crimping machine for crimping, and then dried in the relaxation heat setting machine and packaged to obtain a polylactic acid fiber tow with a single-filament linear density of 31.11 dtex and a total linear density of 4.44 ktex. The crimping wheel used for the crimping has a diameter of 80 mm and a width of 28 mm; the relaxation heat setting temperature is 55°C and the time is 13 minutes.

[0065] After testing, the yarn defects were 0, the coefficient of variation of linear density was 0.44%, the number of crimps was 25 / 25mm, the breaking strength was 56.1cN, the breaking elongation was 45.6%, and the moisture content was 0.23%.

[0066] Example 3

[0067] 1. Pre-spinning steps

[0068] Raw material drying: The polylactic acid chips were dried at 105°C for 5 hours; the modifier masterbatch (the titanium dioxide content in the masterbatch was 45%) was weighed according to 0.8% of the amount of polylactic acid chips and dried at 105°C for 25 hours. After drying, the moisture content of the polylactic acid chips was 0.023‰, and the moisture content of the modifier masterbatch was 0.04‰.

[0069] Screw melting and spinning box assembly filtering and spinning: The dried polylactic acid slices and modifier masterbatch are simultaneously transported to the screw extruder for heating and melting, and the melt is filtered and spun through the assembly in the spinning box to form primary fibers. The screw temperature during heating and melting is 232°C and the spinning box temperature is 224°C; the spinneret has 800 holes, and the spinneret hole shape is Y-shaped.

[0070] Winding and dropping into barrel: the raw fiber is wound by the traction machine and the feeding machine and sent into the wire barrel, and the winding speed is 800m / min.

[0071] 2. Post-spinning steps

[0072] Bunching, oiling, drawing, water bathing, ironing: Bunching the nascent fibers obtained by spinning is followed by oiling, water bath drawing, hot water bathing, and hot water ironing in order to improve physical and mechanical properties and obtain better curling effects. The oiling temperature is 28°C; the water bath drawing temperature is 68°C, the drawing multiple is 2.95 times; the hot water bath temperature is 78°C; and the hot water ironing temperature is 73°C.

[0073] Crimping, relaxation heat setting, and packaging: the fibers after hot water ironing are sent to the crimping machine for crimping, and then dried in the relaxation heat setting machine and packaged to obtain a polylactic acid fiber tow with a single-filament linear density of 6.67 dtex and a total linear density of 4.0 ktex. The crimping wheel used for the crimping has a diameter of 80 mm and a width of 28 mm; the relaxation heat setting temperature is 50°C and the time is 15 minutes.

[0074] After testing, the yarn defects were 0, the coefficient of variation of linear density was 0.51%, the number of crimps was 26 / 25mm, the breaking strength was 13.8cN, the breaking elongation was 37.5%, and the moisture content was 0.21%.

[0075] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a polylactic acid fiber tow, comprising a pre-spinning step and a post-spinning step, in, The pre-spinning step includes drying, melting, spinning and winding the first polylactic acid chips and the modifier masterbatch to obtain the primary fiber; wherein the modifier masterbatch includes the second polylactic acid chips and the modifier, and the modifier is selected from titanium dioxide; The post-spinning step includes sequentially subjecting the primary fibers to oil immersion, drafting, water bath treatment and hot water ironing treatment to obtain intermediate fibers, wherein the temperature of the hot water ironing treatment is 60°C-90°C.

2. The preparation method according to claim 1, It is characterized in that The post-spinning step also includes sequentially subjecting the intermediate fibers to curling, relaxation, heat setting and packaging to obtain the polylactic acid fiber bundles.

3. The preparation method according to claim 1 or 2, It is characterized in that The temperature of the hot water ironing treatment is 70°C-80°C.

4. The preparation method according to any one of claims 1 to 3, It is characterized in that Based on the mass of the modifier masterbatch, the mass content of the modifier is 20%-55%, preferably 35%-45%.

5. The preparation method according to any one of claims 1 to 4, It is characterized in that Based on the mass content of the first polylactic acid chips, the mass content of the modifier masterbatch is 0.4%-0.8%, preferably 0.5%-0.7%.

6. The preparation method according to any one of claims 1 to 5, It is characterized in that In the pre-spinning step, the moisture content of the first polylactic acid slice after drying is less than 0.05‰, and the moisture content of the modifier masterbatch after drying is less than 0.05‰; Preferably, the temperature of the first polylactic acid slice drying treatment is 90°C-110°C, preferably 95°C-105°C, and the time is 3h-12h, preferably 5h-9h; Preferably, the temperature of the drying treatment of the modifier masterbatch is 90° C.-110° C., preferably 95° C.-103° C., and the time is greater than or equal to 24 h, preferably 25 h-40 h.

7. The preparation method according to any one of claims 1 to 6, It is characterized in that In the pre-spinning step, the melt treatment is carried out in a screw extruder. Preferably, during the melt treatment, the screw temperature is 220°C-250°C, preferably 225°C-240°C; and / or The spinning process is carried out in a spinning manifold. Preferably, the spinning process includes filtering and spinning the melt after the melt treatment. More preferably, during the spinning process, the temperature of the spinning manifold is 210° C.-240° C., preferably 215° C.-230° C., the number of spinneret holes used for spinning is 180-800 holes, and the shape of the spinneret holes is Y-shaped or circular; and / or The winding speed of the winding process is 500m / min-1200m / min, preferably 600m / min-1000m / min.

8. The preparation method according to any one of claims 1 to 7, It is characterized in that In the post-spinning step, the spun fibers are bundled before being treated with oil; and / or The temperature of the oil immersion treatment is less than or equal to 40°C, preferably 25°C-35°C; and / or The stretching treatment is a water bath stretching treatment, preferably, the temperature during the stretching treatment is 60°C-80°C, preferably 62°C-75°C, and the stretching ratio is 2.4 times-3.0 times; and / or The temperature of the water bath treatment is 70°C-90°C, preferably 75°C-85°C; and / or During the curling process, the diameter of the curling wheel is 50 mm-100 mm, preferably 60 mm-80 mm, and the width of the curling wheel is 15 mm-30 mm, preferably 20 mm-28 mm; and / or The temperature of the relaxation heat setting treatment is 45°C-60°C, preferably 50°C-55°C, and the time is 5min-20min, preferably 10min-15min.

9. A polylactic acid fiber tow prepared by the preparation method according to any one of claims 1 to 8, preferably, the single-filament linear density of the polylactic acid fiber tow is 5.56 dtex-31.11 dtex, the overall linear density of the tow is 2.22 ktex-4.44 ktex, and the linear density variation coefficient is ≤0.6%.

10. Use of the polylactic acid fiber tow according to claim 9 in cigarette filter rods.