High amino nylon 66 fiber and its preparation process
By introducing high-amino polymers into nylon 66 fibers and performing microencapsulation coating, the problem of dyeing difficulties in nylon 66 fibers has been solved, achieving stable and uniform introduction of high amino content, improving dyeing effect and fiber performance, and making it suitable for large-scale production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIANGXING (FUJIAN) NEW MATERIALS TECH CO LTD
- Filing Date
- 2026-05-07
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies make it difficult to stably, uniformly, and controllably introduce high levels of amino compounds into nylon 66 fibers, resulting in poor dyeing effects and functional dyeing results. Furthermore, amino compounds are prone to decomposition at high temperatures, affecting fiber structure and performance.
The microencapsulation technology of high-amino polymers is used to introduce high-amino polymer powder into nylon 66 fibers and generate nylon 6 or nylon 12 coating layers in situ on its surface to improve compatibility and thermal stability. Then, it is melt-blended with conventional PA66 chips to prepare high-amino functional masterbatch. Finally, high-amino nylon 66 fibers are prepared by precisely controlling the spinning process.
It significantly improves the fiber's adsorption capacity for acid dyes and reactive dyes, enhances dyeing depth and color fastness, and provides good fiber mechanical properties and spinnability, making it suitable for large-scale production.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical fiber technology, specifically to a high-amino nylon 66 fiber and its preparation process. Background Technology
[0002] Nylon 66 (PA66) fiber, also known as nylon 66, is widely used due to its excellent strength, abrasion resistance, and resilience. However, dyeing PA66 fiber, especially for deep, rich colors or certain functional dyeing (such as reactive dyeing), has always presented challenges. The fundamental reason is that nylon dyeing relies primarily on the ionic bonds between the amino groups at the ends of the fiber macromolecular chains and dye molecules (such as acid dyes). Standard PA66 has a low content of terminal amino groups (typically 40-50 mmol / kg), which limits the binding sites with dyes, leading to problems such as low dye saturation, difficulty in improving color fastness, and low dye utilization.
[0003] Increasing the terminal amino content of PA66 fibers is the key to solving the above problems. Directly increasing the amino content of the polymer is difficult to achieve in conventional polymerization processes because it will disrupt the polymerization equilibrium and affect the molecular weight. Therefore, the industry usually adopts copolymerization or blending modification. There are some methods in the existing technology to introduce amino groups by adding amine compounds or modifiers, but they generally have the following problems: (1) Poor compatibility and dispersibility: Small molecule amines or oligomers have poor compatibility with the PA66 matrix and are prone to agglomeration and migration during melt blending and spinning, resulting in uneven fiber structure, reduced strength and poor spinnability. (2) Poor thermal stability of amino groups: Many amino compounds are prone to thermal oxidation or thermal decomposition at the processing temperature of PA66 (about 280°C), resulting in amino group failure and possible bubbles and yellowing. (3) Uncontrollable amino content: Simple physical blending makes it difficult to accurately control the distribution and content of effective amino groups in the final fiber. Summary of the Invention
[0004] The purpose of this invention is to provide a high-amino nylon 66 fiber and its preparation process, which can stably, uniformly and controllably introduce a high content of amino groups and is compatible with the PA66 matrix.
[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:
[0006] A process for preparing high-amino nylon 66 fiber includes the following steps:
[0007] S1. Synthesis of high-amino polymers: Adipic acid is reacted with insufficient hexamethylenediamine to generate a prepolymer salt. Then, the temperature is raised to enter the post-condensation stage. Hexamethylenediamine and / or polyamines are added dropwise in batches and slowly. During the dropwise addition, the intensity change of the characteristic peak of carboxyl groups in the polymer melt is monitored to determine the reaction progress. The final product is granulated and cryogenically pulverized to obtain micron-sized high-amino polymer powder with a number average molecular weight of 300 g / mol-5000 g / mol and a terminal amino content of 200 mmol / kg-5000 mmol / kg.
[0008] S2. Microencapsulation coating treatment of high-amino polymer powder: Disperse high-amino polymer powder in an inert organic solvent to form a uniform slurry; under nitrogen protection, add a catalyst and caprolactam or lauryl lactam to allow caprolactam or lauryl lactam to undergo in-situ ring-opening polymerization on the surface of high-amino polymer powder to generate a nylon 6 or nylon 12 coating layer.
[0009] S3. Preparation of high-amino functional masterbatch: The coated high-amino polymer powder and PA66 chips were melt-blended and granulated by a twin-screw extruder in proportion to obtain high-amino functional masterbatch. The terminal amino content of the high-amino functional masterbatch was precisely determined to be between 150 mmol / kg and 400 mmol / kg.
[0010] S4. Preparation of high-amino nylon 66 fiber: The above-mentioned high-amino functional masterbatch and conventional PA66 chips are dried in the required ratio and then fed into the spinning production line for spinning to obtain high-amino nylon 66 fiber. The amino content Cf of the high-amino nylon 66 fiber is higher than 50 mmol / kg.
[0011] The terminal amino content Cf of the high-amino nylon 66 fiber is precisely calculated and controlled by the following formula:
[0012] Where: C m It is the amino content of high-amino functional masterbatch, C p This refers to the amino content of regular PA66 slices, W. m It is the mass fraction of high-amino functional masterbatch in the mixture. This can be achieved by adjusting W... m It is possible to linearly and predictably prepare high-amino PA66 fibers with any target amino content in the range of 50-200 mmol / kg (or even higher).
[0013] Preferably, the polyamine is diethylenetriamine or triethylenetetramine.
[0014] Preferably, the D50 of the high-amino polymer powder in step S1 is 10μm-50μm.
[0015] Preferably, the mass ratio between the coated high-amino polymer powder and PA66 chips in step S3 is 30:70 to 50:50.
[0016] Preferably, the number average molecular weight of the high-amino polymer powder in step S1 is 300 g / mol to 5000 g / mol, and the terminal amino content is 200 mmol / kg to 5000 mmol / kg.
[0017] Preferably, the terminal amino content of the high-amino functional masterbatch in step S3 is 150 mmol / kg-400 mmol / kg.
[0018] The present invention also provides a high-amino nylon 66 fiber prepared by the above-described preparation process.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] (1) The amino content at the end of the prepared nylon 66 fiber is significantly increased and controllable, which greatly enhances the fiber’s adsorption capacity for acid dyes and reactive dyes, and significantly improves the dyeing depth, color fastness and dye utilization.
[0021] (2) Through innovative HAP synthesis and microencapsulation coating technology, the dispersion problem and thermal stability problem of high polarity additives in PA66 are fundamentally solved, resulting in excellent fiber mechanical properties and spinnability.
[0022] (3) The entire process route is precisely designed. From molecular structure design to final product, the amino content can be designed, monitored and controlled throughout the process, which is suitable for large-scale production.
[0023] The core of this invention lies in designing and synthesizing a high-amino polymer HAP with a structure highly similar to PA66 but with an extremely high content of terminal amino groups. Through innovative "microencapsulation-masterbatch" technology, the problems of its dispersibility and thermal stability in the PA66 matrix are solved. Finally, through precise metering and blending spinning, highly reactive nylon 66 fibers with controllable amino content are prepared.
[0024] The nylon 6 or nylon 12 coating layer of this invention acts like a "capsule shell," serving the following functions: ① Physical isolation: preventing HAP particles from agglomerating during storage and premixing. ② Improved compatibility: the coating layer material has good affinity with PA66, improving its dispersibility in the matrix. ③ Protection of amino groups: reducing HAP's contact with air before processing and in the initial melting stage, improving thermo-oxidative stability. ④ Promotion of interfacial fusion: during melt blending, the coating layer melts first, acting as a "compatibility agent" to promote the entanglement and bonding of HAP and PA66 molecular chains. Detailed Implementation
[0025] Example 1
[0026] This embodiment provides a preparation process for high-amino nylon 66 fiber, including the following steps:
[0027] S1. Synthesis of high-amino polymer HAP:
[0028] In a high-pressure reactor equipped with a stirrer, nitrogen inlet pipe, fractionating column, and condenser receiving device, 14.6 g (0.1 mol) of adipic acid (AA) and 10.2 g (0.088 mol) of hexamethylenediamine (HMD) were added, along with an appropriate amount of deionized water to prepare a nylon salt slurry with a mass fraction of 52%. The air inside the reactor was replaced three times with high-purity nitrogen.
[0029] Subsequently, the system temperature was raised to 210°C within 2 hours using a programmed temperature ramp, while maintaining the pressure at 1.6 MPa for a pre-polymerization reaction for 2 hours. This stage primarily resulted in the formation of oligomers and the removal of most of the moisture. Following this, the pressure was slowly released to atmospheric pressure over 1 hour, while the temperature was simultaneously raised to 250°C, initiating the post-polymerization stage. Using a precision metering pump, a mixed amine solution consisting of 5.8 g (0.05 mol) HMD and 0.5 g (0.003 mol) diethylenetriamine (DETA) was slowly and uniformly added dropwise to the melt over 2.5 hours. During the dropwise addition, the characteristic carboxyl peak (~1710 cm⁻¹) in the polymer melt was monitored in real-time using an online infrared spectrometer. -1 The intensity change of ) is used to determine the progress of the reaction. It should be noted that in other examples, diethylenetriamine can be replaced with triethylenetetramine.
[0030] After the addition was complete, the system was allowed to react for another hour at 250°C under a slight vacuum (-0.05 MPa) to completely remove residual moisture and small molecule byproducts. After the reaction, the polymer melt was extruded under nitrogen pressure, cooled in a water bath, and granulated using a pelletizer to obtain translucent particles. These translucent particles were then subjected to deep embrittlement in liquid nitrogen, followed by pulverization using an ultrafine pulverizer and sieve classification to obtain a white HAP powder with a particle size distribution (D50) of approximately 25 μm. Potentiometric titration showed that the terminal amino group content of the powder was 650 mmol / kg, and gel permeation chromatography (GPC) determined its number-average molecular weight to be approximately 2800 g / mol. It should be noted that in other examples, the D50 of the high-amino polymer powder was selected within the range of 10 μm to 50 μm.
[0031] S2. Microencapsulation of high-amino polymer powder:
[0032] Untreated HAP powder has high surface energy and high polarity, resulting in poor compatibility with PA66 melt. Furthermore, the amino groups are easily oxidized at high temperatures, leading to phase separation when directly blended. In this embodiment, 10g of HAP powder was added to a 100ml reactor equipped with a high-speed dispersing paddle and a reflux condenser, along with 50ml of refined white oil as the dispersion medium. The mixture was stirred at 2000rpm for 30 minutes to form a uniform and stable suspension. Under nitrogen protection, the system was heated to 85°C, and then 2.0g of caprolactam monomer and 0.01g of sodium caprolactam catalyst (0.5% of the monomer mass) were added sequentially. It should be noted that in other examples, the caprolactam monomer can be replaced with lauryl lactam, in which case the corresponding coating layer would be a nylon 12 coating layer.
[0033] The temperature was maintained at 90±2℃, and the reaction was continued for 3 hours. During this period, caprolactam monomers underwent ring-opening polymerization on the surface of HAP powder under the action of a catalyst, forming a polycaprolactam (nylon 6) coating layer in situ. After the reaction was completed, the system was cooled to room temperature, and the solid material was separated by a plate and frame filter press. The solid material was then washed multiple times with acetone to thoroughly remove any residual white oil.
[0034] The resulting coated powder was dried in a vacuum drying oven at 80℃ for 12 hours to obtain HAP powder with a dense nylon 6-layer coating. Scanning electron microscopy (SEM) observation showed that the powder particles were monodisperse, with smooth surfaces and no obvious agglomeration.
[0035] S3. Preparation of high-amino functional masterbatch:
[0036] The coated HAP powder and conventional commercial PA66 chips (terminal amino content approximately 45 mmol / kg) with an intrinsic viscosity of 2.4 were premixed in a high-speed mixer at a mass ratio of 40:60 for 10 minutes. Melt blending and granulation were then performed using a co-rotating twin-screw extruder (L / D ratio L / D = 40:1, screw configuration with multiple kneading blocks to enhance dispersion). The extruder temperatures were set as follows: Zone 1 250℃, Zone 2 265℃, Zone 3 270℃, Zone 4 270℃, and Die 265℃. The screw speed was set to 200 rpm, and the vacuum exhaust port was maintained at -0.08 MPa to remove volatiles. The extrusion process employed a low-temperature, high-shear mode to ensure uniform HAP dispersion without severe degradation.
[0037] The melt was extruded through a die, cooled with water, granulated by a pelletizer, and then dried in a forced-air dryer at 100°C for 6 hours to obtain a high-amino functional masterbatch (labeled MB-A). Titration analysis showed that the amino content of the masterbatch was 260 mmol / kg.
[0038] It should be noted that in other examples, the mass ratio between the coated high-amino polymer powder and PA66 chips is selected in the range of 30:70 to 50:50.
[0039] Preparation of S4 and high-amino nylon 66 fibers:
[0040] The amino content C of the high-amino nylon 66 fiber f Higher than 50 mmol / kg;
[0041] The terminal amino content C of the high-amino nylon 66 fiber f Precise calculation and control are achieved through the following formula:
[0042] Where: C m It is the amino content of high-amino functional masterbatch, C p This refers to the amino content of regular PA66 slices, W. m It is the mass fraction of high-amino functional masterbatch in the mixture.
[0043] The amino content C of the high-amino functional masterbatch MB-A is known. m =260mmol / kg, amino content C of basic PA66 slices p =45mmol / kg, substitute into the target value C f =100, calculate the mass fraction W of the functional masterbatch. m ≈25.6%.
[0044] MB-A masterbatch and base PA66 chips were precisely weighed at a mass ratio of 25.6:74.4 and mixed evenly in a rotary drum mixer. The mixture was vacuum dried at 120°C for 12 hours to reduce the moisture content to below 800 ppm. The dried mixture was then fed into a screw spinning mill. The spinning chamber temperature was set to 285°C, the spinning assembly pressure to 15 MPa, and the spinning speed to 3000 m / min. The nascent fibers were cooled by side-blowing air (air temperature 20°C, air humidity 65%, air velocity 0.5 m / s) and then subjected to two stages of hot drawing, passing sequentially through a first hot roller (temperature 80°C, speed 1200 m / min) and a second hot roller (temperature 160°C, speed 4200 m / min), with a total draw ratio of 3.5. Finally, the fibers were wired and wound to obtain FDY fibers with a specification of 83D / 24F.
[0045] The obtained fibers were sampled and tested. The actual amino content, determined by chemical titration, was 98 mmol / kg, which highly matches the design value. The fiber's breaking strength was 4.7 cN / dtex, and its breaking elongation was 34.5%, exhibiting excellent mechanical properties. A comparative dyeing experiment was conducted using acid blue dye. Under the same dyeing process, the dye uptake rate of the fiber of this invention was 160% higher than that of ordinary PA66 fiber (amino content 45 mmol / kg), and the color was full, uniform, and without color variations.
[0046] Comparative Example 1
[0047] To verify the importance of coating treatment, uncoated HAP powder prepared in Example 1 was directly mixed with PA66 chips at the same amino contribution rate as in Example 1 (i.e., using less powder after conversion), and subjected to the same drying and spinning processes. During extrusion spinning, a significant increase in screw torque fluctuation (±15%) was observed, a small amount of smoke was generated at the spinneret exit, and the spinning breakage rate increased to more than three times the normal level. The resulting fiber strength decreased to 3.9 cN / dtex, and the elongation at break fluctuated greatly. After dyeing, obvious color spots appeared on the fiber surface, and the dyeing uniformity was poor.
[0048] The foregoing has shown and described the basic principles, main features and advantages of this invention. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of this invention. Various changes and modifications can be made to this invention without departing from the spirit and scope of this invention. All such changes and modifications fall within the scope of this invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A preparation process for high-amino nylon 66 fiber, characterized in that, Includes the following steps: S1. Synthesis of high-amino polymers: Adipic acid is reacted with insufficient hexamethylenediamine to generate a prepolymer salt, and then the temperature is raised to enter the post-condensation stage. Hexamethylenediamine and / or polyamines are added dropwise in batches and slowly. During the dropwise addition, the intensity change of the characteristic peak of carboxyl groups in the polymer melt is monitored to determine the reaction progress. The final product is granulated and cryogenically pulverized to obtain micron-sized high-amino polymer powder. S2. Microencapsulation coating treatment of high-amino polymer powder: Disperse high-amino polymer powder in an inert organic solvent to form a uniform slurry; under nitrogen protection, add a catalyst and caprolactam or lauryl lactam to allow caprolactam or lauryl lactam to undergo in-situ ring-opening polymerization on the surface of high-amino polymer powder to generate a nylon 6 or nylon 12 coating layer. S3. Preparation of high-amino functional masterbatch: The coated high-amino polymer powder and PA66 chips are melt-blended and granulated by a twin-screw extruder in a certain proportion to obtain high-amino functional masterbatch. S4. Preparation of high-amino nylon 66 fiber: The above-mentioned high-amino functional masterbatch and conventional PA66 chips are dried in the required ratio and then fed into a spinning production line for spinning to obtain high-amino nylon 66 fiber. The amino content C of the high-amino nylon 66 fiber is... f Higher than 50 mmol / kg; The terminal amino content C of the high-amino nylon 66 fiber f Precise calculation and control are achieved through the following formula: ； Where: C m It is the amino content of high-amino functional masterbatch, C p This refers to the amino content of regular PA66 slices, W. m It is the mass fraction of high-amino functional masterbatch in the mixture.
2. The preparation process of high-amino nylon 66 fiber according to claim 1, characterized in that: The polyamine is diethylenetriamine or triethylenetetramine.
3. The preparation process of high-amino nylon 66 fiber according to claim 1, characterized in that: The D50 of the high-amino polymer powder in step S1 is 10μm-50μm.
4. The preparation process of high-amino nylon 66 fiber according to claim 1, characterized in that: In step S3, the mass ratio between the coated high-amino polymer powder and the PA66 chips is 30:70 to 50:
50.
5. The preparation process of high-amino nylon 66 fiber according to claim 1, characterized in that: The high-amino polymer powder in step S1 has a number average molecular weight of 300 g / mol-5000 g / mol and a terminal amino content of 200 mmol / kg-5000 mmol / kg.
6. The preparation process of high-amino nylon 66 fiber according to claim 1, characterized in that: The terminal amino content of the high-amino functional masterbatch in step S3 is 150 mmol / kg-400 mmol / kg.
7. A high-amino nylon 66 fiber prepared by the preparation process described in any one of claims 1 to 6.