Nylon 12 resin and preparation method thereof, and nylon 12 fiber and preparation method thereof

Abstract

The invention discloses a nylon 12 resin and a preparation method thereof, and a nylon 12 fiber and a preparation method thereof. Preparation raw materials of the laurolactam resin comprise the following components in parts by weight: 100 parts of laurolactam, 0.2-1 part of an end-capping reagent, 4-8 parts of metal salt, 0.1-0.5 part of a catalyst, 0.01-0.05 part of a main antioxidant, 0.01-0.05 part of an auxiliary antioxidant and 5-20 parts of water. The molecular weight distribution (PDI) of the nylon 12 resin is 1.6-1.9, and the prepared nylon 12 fiber has the advantages of few broken ends, high monofilament strength (greater than or equal to 5.5 cN / dtex) and good stretchability, is suitable for spinning of superfine denier specification fiber 30D / 24F, has high color fastness, and is helpful for reducing chromatic aberration and dyeing defect phenomena in the dyeing process.

Description

Technical Field

[0001] This invention relates to the field of nylon polymerization, and more particularly to nylon 12 resin and nylon 12 resin fiber. Background Technology

[0002] Polyamide (commonly known as nylon) is a polymer containing repeating amide groups (-COHN-) in its main chain. It possesses a range of excellent properties, including good mechanical and electrical properties, self-lubrication, solvent resistance, non-toxicity, and ease of molding and processing. As the world's first fiber entirely synthesized chemically, its invention marked the birth of the synthetic fiber industry, revolutionizing modern textiles, materials, and even the military industry. Despite its superior performance and wide range of applications, nylon fiber still has some inherent drawbacks and areas for improvement based on current technology. Compared to natural fibers (such as cotton and silk), nylon (nylon 6) has poor moisture absorption, resulting in fabrics that feel stuffy and uncomfortable to wear, poor breathability and comfort, and a tendency to generate static electricity. This limits the application of nylon materials in high-end fields to some extent.

[0003] Nylon 12 is lightweight, has extremely low water absorption, is abrasion-resistant, and exhibits excellent low-temperature toughness. Its resistance to chemicals, especially salts and alkalis, is far superior to that of Nylon 6. It also shows good resistance to greases, hydrocarbons, alcohols, and detergents, filling the gaps left by Nylon 6 in medical applications (surgical sutures, antibacterial mesh, etc.), marine and water treatment, advanced textiles and composite materials, and precision instruments. However, the spinning industry has extremely high requirements for the molecular weight distribution of the resin. In traditional polymerization, the growth rate of Nylon 12 molecular chains varies, easily forming a system with a wide molecular weight distribution (some chains are too long, some are too short). During spinning, the inconsistent melt flow of the short chains easily leads to stress concentration at the spinneret, causing breakage. Furthermore, the spinning and dyeing processes of nylon are complex, and the color fastness after dyeing is not high, which to some extent limits the application of Nylon 12 in the textile field.

[0004] CN116023654A discloses a method for preparing nylon films, the core of which lies in introducing a small amount of inorganic salt as a heterogeneous nucleating agent. The purpose of this method is to improve the dimensional stability and transparency of the film by promoting nylon crystallization and forming a fine, uniform grain structure. However, this method is only suitable for film-forming processes that pursue high crystallinity and high modulus. For melt spinning, a process that requires good tensile rheology and chain segment orientation capabilities in the spinning channel, excessively high and rapidly formed crystallinity is unsuitable. It leads to increased melt elasticity, premature filament solidification, and increased internal stress, severely affecting the stability of the spinning process and the uniformity and drawability of the fibers. Summary of the Invention

[0005] This invention provides a nylon 12 resin and its preparation method, as well as a nylon 12 fiber and its preparation method. By introducing a specific high concentration of metal salt, a strong interaction is achieved between the metal salt and the amide groups on the nylon molecular chain, thereby controllably disrupting part of the hydrogen bond network in the molten state and effectively suppressing premature and excessive crystallization. This effect fundamentally reduces the apparent viscosity of the nylon melt, improves the melt uniformity and tensile fluidity, and creates ideal conditions for high-speed and stable melt spinning. This invention provides a new method designed specifically for optimizing the spinning and processing performance of nylon from the perspective of in-situ polymerization of materials, which has significant industrial value for producing high-performance, highly uniform nylon fibers. It also improves the spinnability and dyeability of nylon 12 resin.

[0006] To achieve the above technical objectives, the technical solution adopted by the present invention includes:

[0007] A nylon 12 resin with good spinnability and easy dyeing is prepared by means of the following components, in parts by weight: 100 parts dodecyl lactam, 0.2-1 parts end-capping agent, 4-8 parts metal salt, 0.1-0.5 parts catalyst, 0.01-0.05 parts main antioxidant, 0.01-0.05 parts auxiliary antioxidant, and 5-20 parts water.

[0008] As a preferred embodiment, the nylon 12 resin comprises the following components, by weight: 100 parts nylon 12 resin, 0.4-0.8 parts end-capping agent, 4-6 parts metal salt, 0.2-0.4 parts catalyst, 0.02-0.04 parts primary antioxidant, 0.02-0.04 parts secondary antioxidant, and 10-15 parts water.

[0009] This invention also provides a method for preparing the nylon 12 resin, comprising the following steps: according to a ratio,

[0010] (1) Add dodecyl lactam, end-capping agent, metal salt, catalyst, main antioxidant and auxiliary antioxidant and water into the reaction vessel and mix evenly;

[0011] (2) Prepolymerize first, then polymerize later to obtain polyamide melt;

[0012] (3) Cut the polyamide melt into strips and pellets.

[0013] As a preferred embodiment, the capping agent is selected from one or more of ethylenediamine, pentanediamine, hexanediamine, and decanediamine, with decanediamine being preferred.

[0014] As a preferred embodiment, the metal salt is selected from one or more of sodium chloride, calcium chloride, lithium chloride, and magnesium oxide, with calcium chloride being preferred.

[0015] As a preferred embodiment, the catalyst is selected from one or more of zinc phenylphosphide and sodium phenylphosphide.

[0016] As a preferred embodiment, the primary antioxidant is antioxidant 168; the secondary antioxidant is antioxidant 1098.

[0017] As a preferred embodiment, in step (2), the prepolymerization pressure is 2-3 MPa, preferably 2.3-2.5 MPa, and the prepolymerization temperature is 220-260℃, preferably 230-250℃.

[0018] As a preferred embodiment, in step (2), the prepolymerization time is 2-6 hours, preferably 3-6 hours.

[0019] As a preferred embodiment, in step (2), the post-polymerization pressure is -60 to -90 kPa, preferably -70 to -90 kPa, and the post-polymerization temperature is 210-250℃, preferably 220-230℃.

[0020] Another aspect of the present invention provides a method for preparing nylon 12 fiber, comprising the following steps: melt spinning the nylon resin described in the present invention.

[0021] In one optional embodiment, the process parameters for melt spinning include: temperature of 190-280℃; spinning speed of 600-8000m / min; side-blowing air temperature of 0-20℃; side-blowing air speed of 0.3-1m / min; relative humidity of cooling air of 40-85%; stretching ratio of 1.2-5 times; heat setting temperature of 100-160℃; and number of spinnerets of 25-500.

[0022] As a preferred embodiment, in the method for preparing the nylon 12 fiber, the nylon resin is dried to a moisture content of less than 500 ppm, such as by drying at 90°C for 6-24 hours.

[0023] Compared with the prior art, the advantages of the present invention are mainly as follows: (1) The present invention first dissolves the metal salt in deionized water, and it directly participates in the polymerization reaction of nylon 12 resin in ionic form. In the reaction vessel, the metal salt is uniformly dispersed in the polymerization system. As the nylon 12 molecular chain grows, the ions will be "locked" in the resin matrix at the same time, forming a uniform dispersion state at the molecular level, which completely avoids the interface defects caused by the agglomeration of solid particles. This dispersion method will not destroy the regularity of the nylon 12 molecular chain and the continuity of the matrix. Therefore, the mechanical properties of the modified resin, such as tensile strength and impact strength, are basically not reduced compared with pure nylon 12, and are even slightly optimized due to the improvement of dispersion uniformity, which fully meets the requirements of spinning processing for the mechanical properties of resin.

[0024] (2) The efficient exchange of amide bonds enables all polymer chains to grow synchronously and uniformly, ultimately forming a resin system with a narrow and regular molecular weight distribution. This fundamentally solves the industry problem of frequent breakage during the spinning process and significantly improves spinning efficiency and yield.

[0025] (3) The complexation of metal ions with amide bonds disrupts the regular arrangement of nylon 12 molecular chains, hindering crystal growth and perfection, and providing sufficient penetration channels for dye molecules. This not only makes the dye more easily and uniformly adsorbed, but also reduces dye shedding during the dyeing process, significantly improving the color fastness to washing and rubbing of the finished fiber. At the same time, the reduction in crystallinity and the uniformity of the resin system (narrow molecular weight distribution and uniform dispersion of inorganic salts) avoid "uneven dyeing" caused by differences in crystallinity within the fiber, effectively reducing color difference and color spots after dyeing, and improving the appearance consistency and quality stability of the product. Detailed Implementation

[0026] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0027] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0028] Test method:

[0029] (1) Molecular weight distribution test: The test was conducted by a gel permeation chromatography (GPC) system, model WATERS1515, under the condition of hexafluoroisopropanol system.

[0030] (2) Melt index test: The test was conducted using a melt indexer, specifically an Instron MFi5 melt indexer, at 190℃ and 2.16 kg.

[0031] (3) Relative viscosity test: The test was conducted using a relative viscosity meter, specifically a ZVISCO IV6400 fully automatic Ubbelohde viscometer, under the condition of a 0.5 wt% m-cresol solution.

[0032] (4) Differential scanning calorimeter test: The resin melting temperature and crystallization temperature are tested by heating and cooling at a rate of 10°C from room temperature to 250°C, cooling down to room temperature, and then heating up to 250°C again.

[0033] (5) Test method for tensile strength: The test shall be conducted in accordance with the national standard GB / T14344-2008, with a clamping distance of 200 mm and a tensile speed of 200 mm / min;

[0034] (6) Test method for dyeing rate: The dyeing rate of nylon 12 spun fibers was obtained by following GB / T 2378-2003 and using black dye.

[0035] (7) Test method for color fastness: The test shall be conducted in accordance with GB / T 3921-2008 to obtain the color fastness to washing.

[0036] Example 1

[0037] Nylon 12 resin, denoted as PA12-1#, is prepared according to the following steps:

[0038] (1) Addition: 100 parts of dodecyl lactam, 0.4 parts of decanediamine, 4 parts of calcium chloride, 0.2 parts of zinc phenylphosphite, 0.02 parts of antioxidant 168, 0.02 parts of antioxidant 1098, and 10 parts of water, mix evenly.

[0039] (2) Polymerization: Prepolymerization temperature 240℃, prepolymerization pressure 2.4MPa, pressure holding for 6h, pressure release for 2h-4h, cooling to 230℃, vacuum reaction at -90kPa for 90min.

[0040] (3) The polyamide melt is pulled into strips and granulated to obtain polyamide resin particles, which are dried for 16 hours until the moisture content is below 500 ppm.

[0041] (4) Spinning: Spinning temperature 230-250℃, spinning speed 2000m / min, side blowing temperature 17℃, cooling air relative humidity 50%, side blowing speed 0.5m / min, stretching ratio 1.5 times, heat setting temperature 110℃; the number of spinnerets on the spinneret used for spinning is 24, and the fiber specification is 30D / 24F.

[0042] Example 2

[0043] Nylon 12 resin was prepared according to the following steps, which were basically the same as in Example 1, except that the calcium chloride content was increased to 4.5 parts, and it was designated as PA12-2#:

[0044] (1) Addition: 100 parts of dodecyl lactam, 0.4 parts of decanediamine, 4.5 parts of calcium chloride, 0.2 parts of zinc phenylphosphite, 0.02 parts of antioxidant 168, 0.02 parts of antioxidant 1098, and 10 parts of water, mix evenly.

[0045] (2) Polymerization: Prepolymerization temperature 240℃, prepolymerization pressure 2.4MPa, pressure holding for 6h, pressure release for 2h-4h, cooling to 230℃, vacuum reaction at -90kPa for 90min.

[0046] (3) The polyamide melt is pulled into strips and granulated to obtain polyamide resin particles, which are dried for 16 hours until the moisture content is below 500 ppm.

[0047] (4) Spinning: Spinning temperature 230-250℃, spinning speed 2000m / min, side blowing temperature 17℃, cooling air relative humidity 50%, side blowing speed 0.5m / min, stretching ratio 1.5 times, heat setting temperature 110℃; the number of spinnerets on the spinneret used for spinning is 24, and the fiber specification is 30D / 24F.

[0048] Example 3

[0049] Nylon 12 resin was prepared according to the following steps, which were basically the same as in Example 1, except that the amount of calcium chloride was increased to 5 parts, and it was designated as PA12-3#:

[0050] (1) Addition: 100 parts of dodecyl lactam, 0.4 parts of decanediamine, 5 parts of calcium chloride, 0.2 parts of zinc phenylphosphite, 0.02 parts of antioxidant 168, 0.02 parts of antioxidant 1098, and 10 parts of water, mix evenly.

[0051] (2) Polymerization: Prepolymerization temperature 240℃, prepolymerization pressure 2.4MPa, pressure holding for 6h, pressure release for 2h-4h, cooling to 230℃, vacuum reaction at -90kPa for 90min.

[0052] (3) The polyamide melt is pulled into strips and granulated to obtain polyamide resin particles, which are dried for 16 hours until the moisture content is below 500 ppm.

[0053] (4) Spinning: Spinning temperature 230-250℃, spinning speed 2000m / min, side blowing temperature 17℃, cooling air relative humidity 50%, side blowing speed 0.5m / min, stretching ratio 1.5 times, heat setting temperature 110℃; the number of spinnerets on the spinneret used for spinning is 24, and the fiber specification is 30D / 24F.

[0054] Example 4

[0055] Nylon 12 resin was prepared according to the following steps, which were basically the same as in Example 1, except that the calcium chloride content was increased to 5.5 parts, and it was designated PA12-4#:

[0056] (1) Addition: 100 parts of dodecyl lactam, 0.4 parts of decanediamine, 5.5 parts of calcium chloride, 0.2 parts of zinc phenylphosphite, 0.02 parts of antioxidant 168, 0.02 parts of antioxidant 1098, and 10 parts of water, mix evenly.

[0057] (2) Polymerization: Prepolymerization temperature 240℃, prepolymerization pressure 2.4MPa, pressure holding for 6h, pressure release for 2h-4h, cooling to 230℃, vacuum reaction at -90kPa for 90min.

[0058] (3) The polyamide melt is pulled into strips and granulated to obtain polyamide resin particles, which are dried for 16 hours until the moisture content is below 500 ppm.

[0059] (4) Spinning: Spinning temperature 230-250℃, spinning speed 2000m / min, side blowing temperature 17℃, cooling air relative humidity 50%, side blowing speed 0.5m / min, stretching ratio 1.5 times, heat setting temperature 110℃; the number of spinnerets on the spinneret used for spinning is 24, and the fiber specification is 30D / 24F.

[0060] Comparative Example 1

[0061] Nylon 12 resin, denoted as PA12-5#, is prepared according to the following steps:

[0062] (1) Addition: 100 parts of dodecyl lactam, 0.4 parts of decanediamine, 0.2 parts of zinc phenylphosphite, 0.02 parts of antioxidant 168, 0.02 parts of antioxidant 1098, and 10 parts of water, mix evenly.

[0063] (2) Polymerization: Prepolymerization temperature 240℃, prepolymerization pressure 2.4MPa, pressure holding for 6h, pressure release for 2h-4h, cooling to 230℃, vacuum reaction at -90kPa for 90min.

[0064] (3) The polyamide melt is pulled into strips and granulated to obtain polyamide resin particles, which are dried for 16 hours until the moisture content is below 500 ppm.

[0065] (4) Spinning: Spinning temperature 230-250℃, spinning speed 2000m / min, side blowing temperature 17℃, cooling air relative humidity 50%, side blowing speed 0.5m / min, stretching ratio 1.5 times, heat setting temperature 110℃; the number of spinnerets on the spinneret used for spinning is 24, and the fiber specification is 30D / 24F.

[0066] Comparative Example 2

[0067] Nylon 12 resin was prepared according to the following steps. The polymerization stage was basically the same as that of Comparative Example 1. The resin obtained after polymerization was co-extruded with 5 parts of calcium chloride and labeled as PA12-6#.

[0068] (1) Addition: 100 parts of dodecyl lactam, 0.4 parts of decanediamine, 0.2 parts of zinc phenylphosphite, 0.02 parts of antioxidant 168, 0.02 parts of antioxidant 1098, and 10 parts of water, mix evenly.

[0069] (2) Polymerization: Prepolymerization temperature 240℃, prepolymerization pressure 2.4MPa, pressure holding for 6h, pressure release for 2h-4h, cooling to 230℃, vacuum reaction at -90kPa for 90min.

[0070] (3) The polyamide melt is pulled into strips and granulated to obtain polyamide resin particles, which are dried for 16 hours until the moisture content is below 500 ppm.

[0071] (4) Extrusion: The pelletizing resin is blended with 5 parts of calcium chloride, extruded and granulated, and then dried.

[0072] (5) Spinning: Spinning temperature 230-250℃, spinning speed 2000m / min, side blowing temperature 17℃, cooling air relative humidity 50%, side blowing speed 0.5m / min, stretching ratio 1.5 times, heat setting temperature 110℃; the number of spinnerets on the spinneret used for spinning is 24, and the fiber specification is 30D / 24F.

[0073] Comparative Example 3

[0074] Nylon 12 resin was prepared according to the following steps, which were basically the same as in Experiment 1, except that the calcium chloride was reduced to 1 part, and it was designated as PA12-7#:

[0075] (1) Addition: 100 parts of dodecyl lactam, 0.4 parts of decanediamine, 1 part of calcium chloride, 0.2 parts of zinc phenylphosphite, 0.02 parts of antioxidant 168, 0.02 parts of antioxidant 1098, and 10 parts of water, mix evenly.

[0076] (2) Polymerization: Prepolymerization temperature 240℃, prepolymerization pressure 2.4MPa, pressure holding for 6h, pressure release for 2h-4h, cooling to 230℃, vacuum reaction at -90kPa for 90min.

[0077] (3) The polyamide melt is pulled into strips and granulated to obtain polyamide resin particles, which are dried for 16 hours until the moisture content is below 500 ppm.

[0078] (4) Spinning: Spinning temperature 230-250℃, spinning speed 2000m / min, side blowing temperature 17℃, cooling air relative humidity 50%, side blowing speed 0.5m / min, stretching ratio 1.5 times, heat setting temperature 110℃; the number of spinnerets on the spinneret used for spinning is 24, and the fiber specification is 30D / 24F.

[0079] The physical properties of the polyamide resins prepared in each embodiment and comparative example were tested, and the evaluation results are summarized in Table 1 below.

[0080] Table 1. Resin property tests for examples and comparative examples.

[0081] Melt index relative viscosity Elongation at break Melting temperature Crystallization temperature PDI PA12-1# 12.8 1.656 210 176 147 1.82 PA12-2# 11.5 1.685 220 176 147 1.65 PA12-3# 13.5 1.641 208 174 145 1.80 PA12-4# 12.4 1.651 202 174 145 1.61 PA12-5# 13.6 1.639 210 180 150 2.35 PA12-6# 12.7 1.653 130 177 150 2.39 PA12-7# 13.2 1.645 98 180 151 2.29

[0082] The polyamide resins prepared in each embodiment and comparative example were tested for spinning breakage rate, monofilament strength, dyeing rate, yarn evenness (U%), and color fastness to washing. The evaluation results are summarized in Table 2 below.

[0083] Table 2. Resin Evaluation of Examples and Comparative Examples

[0084]

[0085]

[0086] Based on the above results, at the same melt flow rate level, the nylon 12 fiber prepared by this invention can significantly improve the spinnability, dyeing rate and color fastness of nylon 12 resin while ensuring that the tensile strength is at the same level or does not degrade, thus effectively broadening the application fields of nylon 12 fiber clothing.

[0087] Finally, it should be noted that the above embodiments are only used to describe preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that various modifications and improvements made to the technical solutions of the present invention by means of modifications or equivalent substitutions should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A nylon 12 resin, the raw materials for which are prepared contain the following components, in parts by weight: 100 parts dodecanoic acid, 0.2-1 parts end-capping agent, 4-8 parts metal salt, 0.1-0.5 parts catalyst, 0.01-0.05 parts main antioxidant, 0.01-0.05 parts auxiliary antioxidant, and 5-20 parts water.

2. The nylon 12 resin according to claim 1, characterized in that, It contains the following components: 100 parts of nylon 12 resin, 0.4-0.8 parts of end-capping agent, 4-6 parts of metal salt, 0.2-0.4 parts of catalyst, 0.02-0.04 parts of primary antioxidant, 0.02-0.04 parts of secondary antioxidant, and 10-15 parts of water.

3. The nylon 12 resin according to claim 1, characterized in that, The capping agent is selected from one or more of ethylenediamine, pentanediamine, hexamethylenediamine, and decanediamine.

4. The nylon 12 resin according to claim 1, characterized in that, The metal salt is selected from one or more of sodium chloride, calcium chloride, lithium chloride, and magnesium oxide.

5. A method for preparing the nylon 12 resin according to any one of claims 1-4, comprising the following steps: according to a ratio, (1) Add dodecyl lactam, end-capping agent, metal salt, catalyst, main antioxidant and auxiliary antioxidant and water into the reaction vessel and mix evenly; (2) Prepolymerize first, then polymerize later to obtain polyamide melt; (3) Cut the polyamide melt into strips and pellets.

6. The method according to claim 5, characterized in that, In step (2), the prepolymerization pressure is 2-3 MPa, preferably 2.3-2.5 MPa, and the prepolymerization temperature is 220-260℃, preferably 230-250℃.

7. The method according to claim 5, characterized in that, In step (2), the post-polymerization pressure is -60 to -90 kPa, preferably -70 to -90 kPa, and the post-polymerization temperature is 210-250℃, preferably 220-230℃.

8. A nylon 12 fiber, wherein the raw material for its preparation comprises the nylon 12 resin according to any one of claims 1-4 or the nylon 12 resin prepared by the method according to any one of claims 5-7.

9. A method for preparing nylon 12 fiber, comprising the following steps: The nylon 12 resin prepared by the method according to any one of claims 1-4 or any one of claims 5-7 is melt-spun.

10. The method according to claim 9, characterized in that, The process parameters for melt spinning include: Temperature: 190-280℃; Spinning speed: 600-8000m / min; Side blowing temperature: 0-20℃; Side blowing speed: 0.3-1m / min; Cooling air relative humidity: 40-85%; Strength ratio: 1.2-5 times; Heat setting temperature: 100-160℃; Number of spinnerets: 25-500.

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