Modified polyamide, acid dyeable nylon 66 fiber and preparation method and application thereof
By introducing sulfonate or carboxylate ion groups into the nylon 66 molecular chain through copolymerization modification, the problem of insufficient dyeing performance of homopolymer nylon 66 fibers was solved, achieving a dyeing effect with high dyeing rate and low color difference, while maintaining the mechanical properties of the fiber and reducing the preparation cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-07
AI Technical Summary
Homopolymer nylon 66 fiber suffers from low dye uptake and poor level dyeing properties. Existing modification methods may damage the mechanical properties of the fiber or increase the preparation cost.
By introducing sulfonate or carboxylate ionic groups into the nylon 66 molecular chain through copolymerization modification, modified polyamide is formed. The ionic groups act as an in-situ leveling agent during the dyeing process, thereby improving the dyeing rate and maintaining the mechanical properties of the fiber.
A high dyeing rate and low color difference were achieved without the use of additional leveling agents, while maintaining the excellent mechanical properties of the fiber and reducing the production cost.
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Figure CN121801076A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a modified polyamide, an acid-dyeable nylon 66 fiber, its preparation method and application. Background Technology
[0002] Homopolymer nylon 66 (polyhexamethylene adipamide) fiber, with its high strength, abrasion resistance, and stable chemical properties, has become a core material in the manufacture of industrial yarns and high-end textiles. However, in the field of apparel textiles, homopolymer nylon 66 fiber still has limitations in terms of dyeing performance.
[0003] Homopolymer nylon 66 fiber (hereinafter referred to as nylon 66 fiber) has a regular structure, high molecular chain flexibility, strong crystallization ability, dense fiber structure, and strong hydrophobicity, making it difficult for dyes to enter the crystalline regions, resulting in a low dye uptake rate. On the other hand, during the cooling process of melt spinning, the surface layer of the filament cools quickly, has high tension, crystallizes rapidly, and has a low degree of crystallization perfection, while the core layer cools relatively slowly, has low tension, and has a high degree of crystallization perfection. The higher-order structure of nylon 66 fiber, such as crystallization and orientation, is quite sensitive to spinning conditions (spinning temperature, spinning tension). If the spinning conditions are not set properly or the process parameters fluctuate greatly, it is very easy to cause the resulting fiber to have a more obvious core-sheath structure and uneven yarn, which in turn leads to poor dyeing uniformity during dyeing.
[0004] The terminal amine groups of nylon 66 fiber can bind to acid dyes. To overcome the low dye uptake of nylon 66 fiber, the terminal amine groups can bind to acid dyes. To improve its dyeability, the method of increasing the amine content is usually adopted. However, there are limitations to increasing the number of amine groups because amine end-capping can adversely affect its molecular weight. In addition, in practice, modification methods such as blending, copolymerization, and grafting can be used to introduce heterogeneous dye sites that can be easily increased in number. However, the dyeing site of nylon 66 fiber itself is a terminal amine group, and it is generally dyed with acid dyes (which are anionic dyes). Existing technology introduces sulfonate monomers into the nylon 66 molecule to provide a dyeing site for cationic dyes. When preparing nylon 66 fibers that can be dyed with cationic dyes, the terminal amine group will offset part of the effect of the sulfonate dyeing site. The high content of sulfonate monomers is prone to forming "ionomers". The ions in the ionomers will form ion clusters, which will lead to a significant increase in melt viscosity. At the same time, it will strongly reduce the crystallinity of nylon 66 fiber itself, thus bringing additional difficulties to the spinning process and deteriorating the mechanical properties of the fiber.
[0005] The common method to solve the leveling problem of nylon 66 fibers is to add a leveling agent to delay dye uptake and prevent dye from accumulating too quickly in easily dyed areas, thus avoiding color differences. Sulfonate anionic surfactants are commonly used leveling agents for nylon 66 fibers. Before the dye is added, they can bind to the terminal amine groups and occupy some dye sites. However, their binding force to the amine groups is weaker than that of the dye molecules, so they are gradually replaced by the dye in subsequent processes. Therefore, leveling agents sacrifice some dye uptake to reduce color differences.
[0006] In summary, to expand the application of nylon 66 fiber in the textile field, it is urgent to develop a nylon 66 fiber with good dyeing uniformity while maintaining the mechanical properties of nylon 66 fiber to the maximum extent. Summary of the Invention
[0007] To address the aforementioned problems, this invention provides a modified polyamide, an acid-dyeable nylon 66 fiber, its preparation method, and its applications. The acid-dyeable nylon 66 fiber of this invention can achieve excellent leveling effect and high dyeing rate without the use of leveling agents, and still has excellent mechanical properties after modification. The preparation cost is low and the process is simple.
[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a modified polyamide, which is polymerized from a modified monomer, adipic acid and hexamethylenediamine; wherein the modified monomer is a dicarboxylic acid monomer containing sulfonate ion groups or a dicarboxylic acid monomer containing carboxylate ion groups.
[0009] Compared with existing technologies, this invention introduces ionic groups into the polyamide molecular chain through copolymerization modification. The resulting modified polyamide maintains excellent mechanical properties, and the introduced ionic groups act as in-situ leveling agents during the dyeing process, achieving excellent dyeing results with high dyeing rate and low color difference without the need for additional leveling agents. This invention selects modified monomers with sizes similar to those of nylon 66 monomer molecules (adipic acid and hexamethylenediamine), whose introduction has minimal impact on the symmetry of the polyamide molecular chain and will not adversely affect the mechanical properties of the polyamide.
[0010] Preferably, the modified polyamide has a number-average molecular weight of 20,000 to 25,000 and a molecular weight distribution index of 1.9 to 2.4.
[0011] Preferably, the mass ratio of the modified monomer to adipic acid is (0.1~0.4):100, and the molar ratio of adipic acid to hexamethylenediamine is (0.1~5):(0.1~5).
[0012] This invention controls the substitution amount of the modified monomer for adipic acid or hexamethylenediamine monomer within 0.1wt%~0.4wt%, i.e., a mass ratio of (0.1~0.4):100, which does not cause additional difficulties to the polymerization process. The modified monomer of this invention has a similar molecular size to that of nylon 66 monomer, and has little impact on the symmetry of the nylon 66 molecular chain.
[0013] Existing leveling agents require diffusion into the nylon 66 molecule to be effective, but the aggregated structure of nylon 66 is quite dense. Therefore, only a small amount of the added leveling agent achieves its intended leveling effect. In this invention, the sulfonate or carboxylate groups of the modified monomer exist directly within the modified nylon 66 molecule, effectively enhancing its leveling properties. To achieve the same leveling effect, the amount of modified monomer added in this invention is significantly less than the amount of leveling agent typically required.
[0014] It should be noted that when the introduced ionic group is a carboxylate, when the fiber is dyed in a dye bath with acetic acid adjusted to pH, the carboxylate and acetic acid can also act as a buffer solution, stabilizing the pH value of the dye bath, making the dyeing process more stable and the dyeing effect more uniform.
[0015] More preferably, the molar ratio of adipic acid to hexamethylenediamine is 1:1.
[0016] Preferably, the modified monomer is sodium 2-sulfonate terephthalic acid, sodium 5-sulfonate isophthalic acid, or sodium pyromellitic acid monosodium salt.
[0017] Secondly, the present invention provides a method for preparing the above-mentioned modified polyamide, the method comprising the following steps: S1. Mix the modified monomer, adipic acid, hexamethylenediamine and water evenly, add catalyst and antioxidant, and carry out a neutralization reaction under inert gas and 90~100℃ to obtain modified nylon 66 salt solution; S2. The modified nylon 66 salt solution is subjected to a polymerization reaction to obtain modified polyamide.
[0018] Preferably, in step S1, the catalyst is at least one of sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, and zinc hypophosphite; and the antioxidant is at least one of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide, pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), and N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide].
[0019] Preferably, in step S1, the ratio of the mass of the catalyst, the mass of the antioxidant, to the total mass of the modified monomer, adipic acid, and hexamethylenediamine is (0.01~0.03): (0.1~0.2): 100; and the neutralization reaction time is 20~40 min.
[0020] Preferably, in step S2, the polymerization reaction includes the following steps: S2-1. React for 1-3 h at 90~100℃→210~230℃ and atmospheric pressure→1.8~2.2 MPa; S2-2. Maintain a pressure of 1.8~2.2 MPa and react at 210~230℃→270~295℃ for 1~2 h; S2-3. React for 1-3 hours under the conditions of 270~285℃→290~300℃ and 1.8~2.2MPa→normal pressure; S2-4. Maintain a temperature of 290~300℃ and a normal pressure for 5~15 min, then remove a vacuum and react for another 5~15 min to obtain the modified polyamide.
[0021] It should be noted that the "normal pressure" mentioned in this invention refers to ambient atmospheric pressure, and the specific value depends on the geographical environment. For example, the ambient atmospheric pressure is lower in high-altitude areas and higher in low-altitude areas. In this invention, "normal pressure" is defined as ambient atmospheric pressure of 86–106 kPa.
[0022] Thirdly, the present invention provides the application of the above-mentioned modified polyamide or the modified polyamide prepared by the above-mentioned method in the preparation of nylon 66 fiber.
[0023] Fourthly, the present invention provides an acid-dyeable nylon 66 fiber, wherein the acid-dyeable nylon 66 fiber is made from the above-mentioned modified polyamide as raw material.
[0024] Preferably, the acid-dyeable nylon 66 fiber comprises nylon 66 elastic yarn.
[0025] This invention introduces ionic groups into the nylon 66 molecular chain through copolymerization modification. The product can maintain the excellent properties of nylon 66 itself. At the same time, the ionic groups act as an in-situ leveling agent during the fiber dyeing process, so that a high dyeing rate and low color difference can be obtained without the need to add additional leveling agents.
[0026] Fifthly, the present invention also provides a method for preparing the above-mentioned acid-dyeable nylon 66 fiber, comprising the following steps: Modified polyamide is melt-spun to obtain pre-oriented yarn (POY yarn). The pre-oriented yarn is false-twisted to obtain acid-dyeable nylon 66 fiber (DTY yarn).
[0027] Preferably, the acid-dyeable nylon 66 fiber has a single filament fineness of 2~2.7 dtex, a breaking strength ≥4.0 cN / dtex, a breaking elongation of 25%~35%, a crimp shrinkage of 1.5%~5.5%, an oil content of 0.8%~1.2%, and a dyeing color difference ΔE <0.20.
[0028] More preferably, the melt spinning conditions include: spinning temperature 290~300℃, cooling temperature 20~22℃, and winding speed 2800~3000 m / min.
[0029] Further preferably, the false twisting deformation conditions include: first hot roller 90~95℃, second hot roller 185~195℃, stretch ratio 1.65~1.75, D / Y ratio 1.7~1.9, deformation temperature 200~215℃, setting temperature 170~180℃, relaxation rate 3%~5%, network pressure 0.45~0.55MPa, and network density 40~50 pieces / m.
[0030] The acid-dyeable nylon 66 fiber provided by this invention exhibits in-situ leveling properties. First, a modified polyamide is obtained by copolymerizing adipic acid and hexamethylenediamine with a modified monomer. This polyamide is then processed into POY yarn and texturized to obtain DTY yarn. The ionic groups in the modified monomer of this invention provide an in-situ retarding effect within the nylon 66 fiber and do not bind to the dye set. The resulting DTY yarn can achieve excellent leveling effects and high dye uptake without the use of a leveling agent. The modified monomer of this invention is added in small amounts and has a molecular size similar to that of nylon 66 monomer, minimizing its adverse effects on the polymerization process and the molecular structure of nylon 66. The modified nylon 66 fiber still possesses excellent mechanical properties. The acid-dyeable nylon 66 fiber prepared by this invention has low cost, simple process, and broad application prospects. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the slow dyeing mechanism of conventional leveling agent (A) and acid dyeable nylon 66 fiber (B) in this embodiment of the invention. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0033] The slow dyeing mechanism of acid-dyeable nylon 66 fiber with in-situ level dyeing properties in this invention is as follows: Figure 1 As shown.
[0034] When dyeing nylon 66 fibers with acid dyes in an acidic dye bath, a conventional leveling agent containing sulfonate groups is added before the dye (mechanism as follows). Figure 1 As shown in A, ionization will occur, producing -SO3. - Anions, while the terminal amine group of nylon 66 combines with a proton to become -NH3. + As a cationic dye, the leveling agent can electrostatically bind to the terminal amine groups. However, when an acidic dye with the same sulfonate group is added, the binding of the acidic dye to the dye sites becomes more moderate because some of the terminal amine sites are occupied by the leveling agent. When the distribution of terminal amine concentration is uneven due to the uneven fiber structure (distribution of crystalline and amorphous regions), without the moderating effect of a leveling agent, dye molecules will obviously aggregate in easily accessible areas or areas with high amine concentrations, resulting in uneven dyeing. Although the leveling agent will gradually be replaced by the dye in subsequent processes (due to the difference in molecular structure, the latter has a stronger binding ability to amine groups), the dyeing rate will decrease due to incomplete substitution, and the substitution process is strongly affected by dyeing conditions. Therefore, the process design of leveling agents is quite challenging.
[0035] When sulfonate (or carboxylate) groups are introduced onto the nylon molecular chain, such as Figure 1 As shown in Figure B, due to the entanglement of polymers, the terminal amino groups of Nylon 66 are wrapped in the surrounding molecular chains, while the sulfonates on the molecular chains ionize in an acidic dye bath to produce -SO3. - Anions will surround -NH3 + The surrounding structure can also prevent dye molecules from binding to the terminal amine group staining sites. However, as the dye bath temperature is gradually increased to enhance molecular mobility, this surrounding structure becomes unstable, allowing dye molecules to bind to the staining sites again. It is important to note that due to the -SO3 group... - Anions are anchored to the molecular chain and cannot move freely; they interact with -NH3. + The probability of direct binding is very small, so the number of staining sites will not be "wasted", thus improving the staining rate while playing a role in slowing down the staining.
[0036] The reagents and detection methods used for testing the dyeing properties of fibers in this embodiment of the invention are as follows: 1. Dyes Acid Blue R, 2.0% (owf) 2. Dyeing process The dye bath pH is 5. The fiber is dyed at 40℃ and kept at that temperature for 10-15 minutes. The temperature is increased to boiling within 45 minutes at a rate of 1.0-2.0℃ / min. The dyeing continues for another 45 minutes. Then the temperature is gradually reduced to 40℃ and washed with cold water.
[0037] 3. Determination of dyeing percentage Perform the dyeing process as described above, and separately pipette 2 mL of the pre-dye solution and the residual solution after dyeing into 10 mL volumetric flasks. Add acetic acid aqueous solution with pH=5 to the mark, and then measure the λ using a spectrophotometer. max The absorbance A0 and A1 of the dye before and after staining are as follows: Percentage of dye uptake (%) = (l - A1 / A0) × 100% In the formula: A0 represents the absorbance of the pre-dye solution; A1 represents the absorbance of the residual solution.
[0038] 4. Determination of color fastness Test according to GB3920-83, GB251-64, and GB3921-83.
[0039] 5. Determination of color yield and color difference A colorimeter was used for testing.
[0040] 6. Measurement of apparent color depth (K / S) Using the Kubelka-Munk function K / S = (1―R) 2 The formula is calculated as / 2R, where K is the absorption coefficient of the object being tested, S is the scattering coefficient of the object being tested, and R is the reflectance of the object being tested at infinite thickness. The SF600XDatacolor colorimeter was used for testing; each sample was tested 5 times in different areas, and the mathematical average was taken.
[0041] To better illustrate the present invention, further examples are provided below.
[0042] Example 1 This embodiment provides an acid-dyeable nylon 66 fiber, the preparation method of which includes the following steps: (1) At a stirring speed of 10 rpm, 1500 g of deionized water, 3000 g of adipic acid, hexamethylenediamine, and sodium 2-sulfonate terephthalic acid were added to the polymerization reactor in sequence; wherein, the mass ratio of sodium 2-sulfonate terephthalic acid to adipic acid was 0.1:100, and the molar ratio of total amine to acid in the system was 1:1; after adding sodium hypophosphite catalyst with a concentration of 200 ppm of total monomer (i.e., the total amount of adipic acid, hexamethylenediamine, and sodium 2-sulfonate terephthalic acid) and antioxidant N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide with a total monomer concentration of 0.15 wt%, nitrogen was injected to replace the air in the reactor and the stirring speed was increased to 80 rpm, and then the temperature was raised to 90 ℃ and reacted for 30 min to complete the neutralization and salt formation.
[0043] (2) Heating and pressurizing stage: The temperature inside the reactor is raised to 220℃ within 2 hours, and the pressure is raised from 0MPa to 2.0MPa; Heating and pressurizing stage: The reactor is pressurized at 2.0MPa for 1.5 hours, and the temperature inside the reactor is gradually raised to 280℃ during the pressurizing and venting stage; Heating and depressurizing stage: After the temperature inside the reactor reaches 280℃, the pressure is depressurized to atmospheric pressure for 2 hours. When the pressure is depressurized, the temperature inside the reactor rises to 300℃; After the pressure inside the reactor drops to atmospheric pressure, the reaction is carried out for 10 minutes, and then the pressure inside the reactor is controlled at -0.06MPa for 10 minutes. Then nitrogen is injected to a slightly positive pressure, and the material is discharged from the outlet. The material is cooled and cast in a water bath and then granulated to obtain modified copolyamide; The number average molecular weight of the obtained modified polyamide is 25000 and the molecular weight distribution index is 2.4.
[0044] (3) The above-mentioned modified copolyamide is spun into POY by metering, spinneret extrusion, cooling, oiling and winding, and then further processed into DTY by guiding, heating and stretching, false twisting, heat setting and winding. The parameters for the POY process are: spinning temperature 300℃, cooling temperature 20℃, and winding speed 2800m / min; the parameters for the DTY process are: first hot roller 95℃, second hot roller 195℃, draw ratio 1.65, D / Y ratio 1.7, deformation temperature 215℃, setting temperature 180℃, relaxation rate 5%, network pressure 0.55MPa, and network density 50 pieces / m.
[0045] Example 2 This embodiment provides an acid-dyeable nylon 66 fiber, the preparation method of which includes the following steps: (1) At a stirring speed of 10 rpm, 1500 g of deionized water, 3000 g of adipic acid, hexamethylenediamine, and sodium isophthalic acid 5-sulfonate were added to the polymerization reactor in sequence; wherein, the mass ratio of sodium isophthalic acid 5-sulfonate to adipic acid was 0.2:100, and the molar ratio of total amine to acid in the system was 1:1; after adding 200 ppm of sodium hypophosphite catalyst and 0.15 wt% of antioxidant N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide, nitrogen was injected to replace the air in the reactor and the stirring speed was increased to 80 rpm, and then the temperature was raised to 90 ℃ and reacted for 30 min to complete the neutralization and salt formation.
[0046] (2) Heating and pressurizing stage: The temperature inside the reactor is raised to 220℃ within 2 hours, and the pressure is raised from 0MPa to 2.05MPa; Heating and pressurizing stage: The reactor is pressurized at 2.05MPa for 1.5 hours, and the temperature inside the reactor is gradually raised to 280℃ during the pressurizing and venting stage; Heating and depressurizing stage: After the temperature inside the reactor reaches 280℃, the pressure is depressurized to atmospheric pressure for 2 hours. When the pressure is depressurized, the temperature inside the reactor rises to 300℃; After the pressure inside the reactor drops to atmospheric pressure, the reaction is carried out for 10 minutes, and then the pressure inside the reactor is controlled at -0.06MPa for 10 minutes. Then nitrogen is injected to a slightly positive pressure, and the material is discharged from the outlet. The material is cooled and cast in a water bath and then granulated to obtain modified copolyamide; The number average molecular weight of the obtained modified polyamide is 24000 and the molecular weight distribution index is 2.2.
[0047] (3) The above-mentioned modified copolyamide is spun into POY by metering, spinneret extrusion, cooling, oiling and winding, and then further processed into DTY by guiding, heating and stretching, false twisting, heat setting and winding. The parameters for the POY process are: spinning temperature 298℃, cooling temperature 21℃, and winding speed 2900m / min; the parameters for the DTY process are: first hot roller 93℃, second hot roller 195℃, draw ratio 1.65, D / Y ratio 1.7, deformation temperature 212℃, setting temperature 178℃, relaxation rate 5%, network pressure 0.55MPa, and network density 50 pieces / m.
[0048] Example 3 This embodiment provides an acid-dyeable nylon 66 fiber, the preparation method of which includes the following steps: (1) At a stirring speed of 10 rpm, 1500 g of deionized water, 3000 g of adipic acid, hexamethylenediamine, and sodium pyromellitic acid were added to the polymerization reactor in sequence; wherein, the mass ratio of sodium pyromellitic acid to adipic acid was 0.3:100, and the molar ratio of total amine to acid in the system was 1:1; after adding 200 ppm of sodium hypophosphite catalyst and 0.15 wt% of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide antioxidant, nitrogen was injected to replace the air in the reactor and the stirring speed was increased to 80 rpm, and then the temperature was raised to 100℃ and reacted for 30 min to complete the neutralization and salt formation.
[0049] (2) Heating and pressurizing stage: The temperature inside the reactor is raised to 220℃ within 2 hours, and the pressure is raised from 0MPa to 2.1MPa; Heating and pressurizing stage: The pressure inside the reactor is maintained at 2.1MPa for 1.5 hours. During the pressure maintenance and venting stage, the temperature inside the reactor is gradually raised to 280℃; Heating and depressurizing stage: After the temperature inside the reactor reaches 280℃, the pressure is depressurized to atmospheric pressure for 2 hours. When the pressure is depressurized, the temperature inside the reactor rises to 298℃; After the pressure inside the reactor drops to atmospheric pressure, the reaction is carried out for 10 minutes. Then, the pressure inside the reactor is controlled at -0.06MPa for 10 minutes. Then, nitrogen is injected to a slightly positive pressure. The material is discharged from the outlet, cooled in a water bath, cast into strips, and granulated to obtain modified copolyamide; The number average molecular weight of the obtained modified polyamide is 23000, and the molecular weight distribution index is 2.1.
[0050] (3) The above-mentioned modified copolyamide is spun into POY by metering, spinneret extrusion, cooling, oiling and winding, and then further processed into DTY by guiding, heating and stretching, false twisting, heat setting and winding. The parameters for the POY process are: spinning temperature 297℃, cooling temperature 20℃, and winding speed 2950m / min; the parameters for the DTY process are: first hot roller 92℃, second hot roller 190℃, draw ratio 1.75, D / Y ratio 1.8, deformation temperature 210℃, setting temperature 175℃, relaxation rate 4.5%, network pressure 0.50MPa, and network density 48 cells / m.
[0051] Comparative Example 1 This comparative example provides a method for preparing nylon 66 fiber, the steps and parameters of which are similar to those of Example 1, except that sodium 2-sulfonate terephthalic acid is not added in step (1). The remaining steps and parameters are the same as those of Example 1 and will not be repeated here.
[0052] Comparative Example 2 This comparative example provides a method for preparing nylon 66 fiber, the steps and parameters of which are similar to those of Example 2, except that sodium isophthalic acid 5-sulfonate is not added in step (1). The remaining steps and parameters are the same as those of Example 2 and will not be repeated here.
[0053] Comparative Example 3 This comparative example provides a method for preparing nylon 66 fiber, the steps and parameters of which are similar to those of Example 3, except that in step (1), sodium pyromellitic acid is not added. The remaining steps and parameters are the same as those of Example 3 and will not be repeated here.
[0054] Detection Example 1 The dyeing rate, apparent color depth (K / S), color difference, and fastness of nylon 66 fibers obtained according to the methods described in Examples 1-3 and Comparative Examples 1-3 were tested respectively, and the results are shown in Table 1.
[0055] Table 1 Dyeing performance test of Nylon 66 fiber
[0056] As shown in Table 1, the dyeing properties of nylon 66 fibers obtained by the methods described in Examples 1-3 are significantly better than those obtained by the methods described in Comparative Examples 1-3, including dyeing rate, apparent color depth (K / S), color difference, and fastness. In particular, the dyeing rate of the nylon 66 fibers obtained in Example 1 is as high as 86.1%.
[0057] Detection Example 2 The nylon 66 fibers obtained in Examples 1-3 and Comparative Examples 1-3 were tested according to GB / T 14343-2008 "Test Method for Linear Density of Chemical Fiber Filaments", GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", GB / T 6506-2017 "Test Method for Curling Properties of Synthetic Fiber Textured Yarns", and GB / T 6504-2017 "Test Method for Oil Content of Chemical Fibers", and the results are as follows: The acid-dyeable nylon 66 fiber with in-situ level dyeing properties prepared in Example 1 has a single filament fineness of 2.7 dtex, a breaking strength of 4.7 cN / dtex, a breaking elongation of 35.0%, a crimp shrinkage of 3.70%, a linear density deviation of 1.8%, a breaking strength CV value of 3.7%, a breaking elongation CV value of 7.2%, a crimp shrinkage CV value of 6.9%, and an oil content of 1.0%. All of these indicators are close to those of Comparative Example 1.
[0058] The acid-dyeable nylon 66 fiber with in-situ level dyeing properties prepared in Example 2 has a single filament fineness of 2.6 dtex, a breaking strength of 4.5 cN / dtex, a breaking elongation of 33.0%, a crimp shrinkage of 3.62%, a linear density deviation rate of 1.7%, a breaking strength CV value of 3.5%, a breaking elongation CV value of 7.1%, a crimp shrinkage CV value of 7.3%, and an oil content of 1.1%. All of these indicators are close to those of Comparative Example 2.
[0059] The acid-dyeable nylon 66 fiber with in-situ level dyeing properties prepared in Example 3 has a single filament fineness of 2.5 dtex, a breaking strength of 4.6 cN / dtex, a breaking elongation of 30.0%, a crimp shrinkage of 4.67%, a linear density deviation of 1.8%, a breaking strength CV value of 3.4%, a breaking elongation CV value of 7.3%, a crimp shrinkage CV value of 6.9%, and an oil content of 1.2%. All indicators are close to those of Comparative Example 3.
[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A modified polyamide, characterized in that, It is polymerized from modified monomers, adipic acid and hexamethylenediamine; the modified monomers are dicarboxylic acid monomers containing sulfonate ion groups or dicarboxylic acid monomers containing carboxylate ion groups.
2. The modified polyamide according to claim 1, characterized in that, The modified polyamide has a number-average molecular weight of 20,000 to 25,000 and a molecular weight distribution index of 1.9 to 2.
4.
3. The modified polyamide according to claim 1, characterized in that, The mass ratio of the modified monomer to adipic acid is (0.1~0.4):100, and the molar ratio of adipic acid to hexamethylenediamine is (0.1~5):(0.1~5); the modified monomer is sodium 2-sulfonate terephthalic acid, sodium 5-sulfonate isophthalic acid, or sodium pyromellitic acid monosodium salt.
4. The method for preparing the modified polyamide according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Mix the modified monomer, adipic acid, hexamethylenediamine and water evenly, add catalyst and antioxidant, and carry out a neutralization reaction under inert gas and 90~100℃ to obtain modified nylon 66 salt solution; S2. The modified nylon 66 salt solution is subjected to a polymerization reaction to obtain modified polyamide.
5. The method for preparing the modified polyamide according to claim 4, characterized in that, In step S1, the catalyst is at least one of sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, or zinc hypophosphite; the antioxidant is at least one of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide, pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), or N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide]. In step S1, the ratio of the mass of the catalyst, the mass of the antioxidant, to the total mass of the modified monomer, adipic acid, and hexamethylenediamine is (0.01~0.03): (0.1~0.2): 100; In step S1, the neutralization reaction takes 20 to 40 minutes.
6. The method for preparing the modified polyamide according to claim 4, characterized in that, In step S2, the polymerization reaction includes the following steps: S2-1. React for 1-3 h at 90~100℃→210~230℃ and atmospheric pressure→1.8~2.2 MPa; S2-2. Maintain a pressure of 1.8~2.2 MPa and react at 210~230℃→270~295℃ for 1~2 h; S2-3. React for 1-3 hours under the conditions of 270~285℃→290~300℃ and 1.8~2.2MPa→normal pressure; S2-4. Maintain a temperature of 290~300℃ and react at normal pressure for 5~15 min, then react under vacuum for another 5~15 min to obtain modified polyamide.
7. The use of the modified polyamide according to any one of claims 1 to 3 or the modified polyamide prepared by the method according to any one of claims 4 to 6 in the preparation of nylon 66 fiber.
8. An acid-dyeable nylon 66 fiber, characterized in that, The acid-dyeable nylon 66 fiber is made from the modified polyamide described in any one of claims 1 to 3.
9. The acid-dyeable nylon 66 fiber according to claim 8, characterized in that, The acid-dyeable nylon 66 fiber includes nylon 66 elastic yarn.
10. The method for preparing acid-dyeable nylon 66 fiber according to claim 9, characterized in that, Includes the following steps: The modified polyamide was melt-spun to obtain pre-oriented yarn; The pre-oriented yarn is false-twisted to obtain acid-dyeable nylon 66 fiber.