Yellow polylactic acid fiber with high tinting strength and high spinnability and preparation method thereof

Abstract

The invention discloses a yellow polylactic acid fiber with high tinting strength and high spinnability and a preparation method thereof.The yellow polylactic acid fiber is prepared by mixing polylactic acid matrix resin and high-concentration yellow polylactic acid color master batch and then conducting a melt spinning process, and the high-concentration yellow polylactic acid color master batch is prepared from, by weight, 80 parts of polylactic acid resin, 20 parts of yellow pigment, 20 parts of polycarboxylate superplasticizer, 1 part of antioxidant and 1 part of lubricant. 0.3-0.8 part of a hydrolysis stabilizer and 1-2 parts of a composite lubricant; the weight ratio of the polylactic acid matrix resin to the high-concentration yellow polylactic acid color master batch is (20-30): 1; the yellow pigment is C.I. Pigment yellow 139; the hydrolysis stabilizer is a carbodiimide compound. The composite lubricant is a compound of ethylene bis stearamide and oxidized polyethlene wax in a weight ratio of 1: 1. The invention relates to the technical field, and particularly provides a yellow polylactic acid fiber with high tinting strength and high spinnability and a preparation method thereof.

Description

Technical Field

[0001] This invention relates to the field of fiber coloring and processing, specifically to a yellow polylactic acid fiber with high coloring power and high spinnability and its preparation method. Background Technology

[0002] With increasing environmental awareness, the demand for biodegradable polylactic acid (PLA) fibers in the textile industry is growing. PLA fiber is a biodegradable polyester synthesized from lactic acid, possessing excellent biocompatibility, biodegradability, and environmental friendliness, making it an important material for bio-based chemical fibers. Due to its superior physicochemical properties and environmental attributes, PLA fiber is widely used in high-end apparel, home textiles, and medical fields. In the production process of PLA fiber, coloring is a key process that directly affects the final application performance and market value of the fiber.

[0003] Currently, the coloring of polylactic acid (PLA) fibers mainly employs the masterbatch method for melt spinning. This method boasts advantages such as a short process, no pollution, and high efficiency, and has become the mainstream process in the industry. In existing technologies, the pigment concentration in masterbatches commonly used in the industry is between 0.5% and 3% to balance color depth and spinnability. However, when a bright, deep yellow is required, such as for high-demand applications like warning clothing and sportswear, this concentration is often insufficient to achieve the ideal color depth. The existing technology has the following drawbacks:

[0004] (1) The contradiction between high-concentration coloring and spinnability: If the concentration of yellow pigment in the masterbatch is simply increased to 4% or higher, a large number of pigment particles will seriously damage the rheological properties of polylactic acid melt, increase melt viscosity, and easily cause the spinneret channel to be blocked, resulting in spinning pressure fluctuations, a surge in breakage rate, and inability to achieve stable continuous production.

[0005] (2) The contradiction between high-concentration coloring and fiber strength: High pigment particles act as stress concentration points in the fiber, which will significantly weaken the mechanical properties of the fiber, leading to a decrease in breaking strength and elongation; the trace metal ions that may be contained in the pigment will catalyze the hydrolytic degradation of polylactic acid at the processing temperature, further deteriorating the fiber strength.

[0006] (3) The contradiction between high-concentration coloring and color uniformity: The higher the pigment concentration, the more difficult it is to achieve nanoscale uniform dispersion in polylactic acid matrix, which easily leads to agglomeration, color spots or color stripes, resulting in uneven fiber color and affecting the appearance quality of finished products. Summary of the Invention

[0007] The technical problem to be solved by the present invention is the poor spinnability, deterioration of fiber properties and uneven color caused by high concentration of pigments in the prior art.

[0008] This invention provides the following technical invention: A yellow polylactic acid fiber with high coloring power and high spinnability is prepared by mixing polylactic acid matrix resin and high-concentration yellow polylactic acid masterbatch and then performing a melt spinning process. The high-concentration yellow polylactic acid masterbatch consists of the following components in parts by weight: 80 parts polylactic acid resin, 20 parts yellow pigment, 0.3-0.8 parts hydrolytic stabilizer, and 1-2 parts composite lubricant.

[0009] Preferred technical solution 1: The weight ratio of polylactic acid matrix resin to high-concentration yellow polylactic acid masterbatch is (20-30):1.

[0010] Preferred technical solution 2: The yellow pigment is CI Pigment Yellow 139.

[0011] Preferred technical solution 3: The hydrolysis stabilizer is a carbodiimide compound.

[0012] Preferred technical solution four: The composite lubricant is a mixture of ethylene bis-stearamide and oxidized polyethylene wax in a weight ratio of 1:1.

[0013] This invention discloses a method for preparing yellow polylactic acid fibers with high coloring power and high spinnability, specifically comprising the following steps:

[0014] Step 1: Raw material pretreatment: The high-concentration yellow polylactic acid masterbatch and polylactic acid matrix resin are vacuum dried at 85-95℃ for 8-12 hours to reduce the moisture content of the raw materials to below 150ppm.

[0015] Step 2, Mixing and Melt Spinning: The dried masterbatch and polylactic acid matrix resin are mixed evenly in a certain proportion and fed into the screw extruder. The temperature of each zone of the screw extruder is controlled as follows: Zone 1 180-190℃, Zone 2 210-220℃, Zone 3 210-220℃, Zone 4 210-220℃;

[0016] Step 3, Extrusion Molding and Cooling: The melt is extruded through a spinneret to form a fine melt stream, which is then cooled and solidified using a side-blowing method to form nascent fibers;

[0017] Step 4, Stretching and Heat Setting: The cooled nascent fibers are subjected to primary stretching at 75-85℃, with a stretching ratio of 1.5-2.5 times; then the stretched fibers are subjected to heat setting at 85-95℃ for 5-10 seconds.

[0018] Step 5, winding: The heat-set fibers are wound into a cylinder at a speed of 2800-3700 m / min to obtain the yellow polylactic acid fiber.

[0019] The present invention proposes a yellow polylactic acid fiber with high coloring power and high spinnability, and a method for preparing the same. The beneficial effects achieved by using the above scheme are as follows:

[0020] (1) By selecting CI pigment yellow 139 with excellent thermal stability and dispersibility, and using a composite lubricant composed of EBS and OPE wax, the lubricant can effectively reduce the melt viscosity, reduce the friction between the melt and the equipment, and promote the dispersion of pigment particles in melts with high pigment content. This ensures that the melt rheological properties are stable and the spinneret pressure fluctuation is small at a high fiber pigment content of 4%, thus achieving continuous and stable spinning with a low breakage rate.

[0021] (2) The addition of carbodiimide hydrolysis stabilizers effectively inhibited the hydrolysis reaction caused by pigments and trace amounts of moisture during processing, ensuring the polymer molecular weight and maintaining the fiber's tensile strength above 3.0 cN / dtex. Test data showed that the tensile strength of the fiber at a 4% concentration was 3.2 cN / dtex, while that at a 5% concentration was only 2.9 cN / dtex, with a mechanical property retention rate improved by approximately 10%.

[0022] (3) The specific combination of components and the optimized cooling forming process provide conditions for the full diffusion and orientation of pigment molecules in the fiber, avoiding uneven color phenomena such as color spots and stripes. The resulting fiber has a full and uniform color, and its color fastness to washing and rubbing both reach level 4 or above, meeting the requirements of high-end textiles;

[0023] (4) All process parameters from masterbatch formulation to spinning, drawing and heat setting have been synergistically optimized for high pigment content PLA system. The process window is clear and the adaptability is strong, which can realize the stable and efficient production of high quality yellow polylactic acid fiber. Detailed Implementation

[0024] The technologies described below will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Example 1: Preparation of 4% yellow masterbatch and fiber

[0026] A yellow polylactic acid fiber with high coloring power and high spinnability comprises 96 parts of polylactic acid resin, 4 parts of CI pigment yellow 139, 0.5 parts of carbodiimide hydrolysis stabilizer, and 1.5 parts of composite lubricant.

[0027] Color masterbatch preparation: Polylactic acid resin was vacuum dried at 85℃ for 8 hours, and then added to a high-speed mixer along with CI pigment yellow 139, hydrolytic stabilizer, and composite lubricant. The mixture was mixed at 1000 r / min for 12 minutes. The mixture was fed into a twin-screw extruder, and the extrusion temperature was controlled as follows: Zone 1 160℃, Zone 2 175℃, Zone 3 180℃, Zone 4 185℃, and screw speed 350 r / min. After melt mixing, water cooling, and pelletizing, a special color masterbatch with a particle size of 2-3 mm was obtained. The above special color masterbatch was mixed with polylactic acid matrix resin at a weight ratio of 1:20, and the final pigment concentration in the fiber was 4%.

[0028] Preparation steps for yellow polylactic acid fiber:

[0029] (1) Raw material pretreatment: Place the special color masterbatch and polylactic acid matrix resin in a vacuum dryer and dry them at 85-95℃ for 8-12 hours. The moisture content is found to be below 150ppm.

[0030] (2) Mixing: Add the dried material to a high-speed mixer and stir at 1500r / min for 10 minutes until it is evenly mixed;

[0031] (3) Melt spinning: The mixture is fed into a twin-screw extruder and the temperature is controlled as follows: Zone 1 180-190℃, Zone 2 210-220℃, Zone 3 210-220℃, Zone 4 210-220℃, and the screw speed is 320r / min.

[0032] (4) Cooling and forming: After the melt is extruded through the spinneret, it enters the side blowing cooling device, and the side blowing temperature is controlled at 22℃, the wind speed is 0.4m / s, the wind temperature fluctuation is ±0.5℃, and the temperature of the nascent fiber drops to 45℃.

[0033] (5) Stretching and heat setting: The nascent fibers are fed into the stretching machine and stretched 1.5-2.5 times at 75-85℃; then they enter the heat setting roller and are heat set at 85-95℃ for 5-10 seconds with a setting tension of 2.2cN / dtex.

[0034] (6) Winding: The cylinder is wound by a JW-800 type winding machine at a speed of 2800-3700m / min with a winding tension of 2.0cN / dtex.

[0035] Example 2: 5% yellow masterbatch and fiber were prepared using the same formula as in Example 1, but the pigment concentration was increased to 5%, while other conditions remained unchanged, and spinning comparison was carried out.

[0036] Performance testing

[0037] The performance of the yellow polylactic acid fibers obtained in Example 1 and the comparative example was tested, and the results are as follows:

[0038]

[0039] Conclusion: The test results show that the 4% pigment concentration used in this invention is a performance inflection point. At this concentration, the fiber can simultaneously achieve a bright yellow color, excellent mechanical properties, and stable spinnability. However, when the concentration is further increased to 5%, although the color is deeper, spinnability and fiber strength deteriorate significantly, and color fastness also decreases. This proves the scientific validity and industrial value of the 4% concentration ratio in this invention.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, material, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, material, or apparatus.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A yellow polylactic acid fiber with high coloring power and high spinnability, characterized in that, The high-concentration yellow polylactic acid masterbatch is prepared by melt spinning after mixing polylactic acid matrix resin with high-concentration yellow polylactic acid masterbatch. The high-concentration yellow polylactic acid masterbatch consists of the following components in parts by weight: 80 parts polylactic acid resin, 20 parts yellow pigment, 0.3-0.8 parts hydrolytic stabilizer, and 1-2 parts composite lubricant.

2. The yellow polylactic acid fiber with high coloring power and high spinnability according to claim 1, characterized in that, The weight ratio of polylactic acid matrix resin to high-concentration yellow polylactic acid masterbatch is (20-30):

1.

3. The yellow polylactic acid fiber with high coloring power and high spinnability according to claim 1, characterized in that, The yellow pigment is CI Pigment Yellow 139.

4. The yellow polylactic acid fiber with high coloring power and high spinnability according to claim 1, characterized in that, The hydrolysis stabilizer is a carbodiimide compound.

5. The yellow polylactic acid fiber with high coloring power and high spinnability according to claim 1, characterized in that, The composite lubricant is a mixture of ethylene bis-stearamide and oxidized polyethylene wax in a weight ratio of 1:

1.

6. A method for preparing a yellow polylactic acid fiber with high coloring power and high spinnability according to any one of claims 1-5, characterized in that, Specifically, the following steps are included: Step 1: Raw material pretreatment: The high-concentration yellow polylactic acid masterbatch and polylactic acid matrix resin are vacuum dried at 85-95℃ for 8-12 hours to reduce the moisture content of the raw materials to below 150ppm. Step 2, Mixing and Melt Spinning: Mix the dried masterbatch and polylactic acid matrix resin evenly in proportion and feed it into the screw extruder; control the temperature of each zone of the screw extruder as follows: Zone 1 180-190℃, Zone 2 210-220℃, Zone 3 210-220℃, Zone 4 210-220℃. Step 3, Extrusion Molding and Cooling: The melt is extruded through a spinneret to form a fine melt stream, which is then cooled and solidified using a side-blowing method to form nascent fibers; Step 4, Stretching and Heat Setting: The cooled nascent fibers are subjected to primary stretching at 75-85℃, with a stretching ratio of 1.5-2.5 times; then the stretched fibers are subjected to heat setting at 85-95℃ for 5-10 seconds. Step 5, winding: The heat-set fibers are wound into a cylinder at a speed of 2800-3700 m / min to obtain the yellow polylactic acid fiber.

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