A high-density composite fiber containing a polyamide and a method for producing the same

Abstract

The application belongs to the technical field of composite fibers, and particularly relates to a high-density composite fiber containing polyamide and a preparation method thereof. The high-density composite fiber containing polyamide is obtained by blending modified polyamide fibers and polyester fibers; the modified polyamide fibers are obtained by melt spinning of modified polyamide; and the preparation method of the modified polyamide comprises the following steps: reacting caprolactam and adipic acid under the action of an opening agent to obtain a polyamide prepolymer; and reacting the polyamide prepolymer, a modifier A and a modifier B under the action of a catalyst to obtain the modified polyamide; the modifier A is a vanillin Schiff base compound; and the modifier B is a plant oil modified palm wax. The fabric prepared from the high-density composite fiber containing polyamide has excellent waterproofness and sun protection, and also has excellent wrinkle resistance; and the fabric is not prone to the phenomena of unclear opening, disordered yarn, fluffing, broken yarn and the like during preparation of the high-density fabric.

Description

Technical Field

[0001] This invention belongs to the field of composite fiber technology, specifically relating to a high-density composite fiber containing polyamide and its preparation method. Background Technology

[0002] Polyamide fibers have excellent abrasion resistance and windproof properties, and are widely used in outdoor clothing, especially in protective clothing such as windbreakers.

[0003] However, traditional polyamide fibers have the following technical problems: (1) They have strong hydrophilicity and are prone to absorbing moisture in humid or rainy environments, causing the fabric to become wet; (2) They have limited ability to block ultraviolet rays and are difficult to effectively protect the skin from ultraviolet damage under strong sunlight; (3) They are prone to wrinkling. Although they have good elasticity, they are easy to wrinkle. The above technical problems limit their application in wide-cut outdoor clothing.

[0004] The applicant's previous technical solution: Chinese patent with authorization announcement number CN 118087087 B discloses a waterproof and sun-proof polyamide fiber and fabric, comprising the following components by weight: 40-60 parts of polyamide thermoplastic elastomer, 30-50 parts of composite polyamide elastomer, 10-20 parts of reinforcing elastomer, 6-8 parts of composite microparticles, and 1-2 parts of calcium stearate. This technical solution strengthens the polyamide thermoplastic elastomer by preparing composite polyamide elastomer, reinforcing elastomer, and composite microparticles, which not only effectively enhances the tensile properties of polyamide fiber, but also improves the abrasion resistance and long-lasting waterproof, sun-proof, and antibacterial properties of polyamide fiber fabric.

[0005] Chinese Patent Publication No. CN 114875554 B discloses a method for preparing a garment with stain-resistant and wrinkle-resistant fabric, comprising the following steps: (1) preparing modified polyamide fibers; (2) using modified polyamide fibers and polyvinyl acetal fibers to obtain warp yarns, and using modified polyamide fibers and viscose fibers to obtain weft yarns; (3) using the warp and weft yarns in an alternating up-down weaving pattern to prepare a garment fabric rough; (4) post-processing the garment fabric rough to obtain the garment fabric; (5) processing the garment fabric to complete the garment preparation. The garment fabric obtained by this technical solution has superior oil stain resistance and wrinkle resistance compared to conventional polyamide fiber fabrics.

[0006] However, all of the above technical solutions use fluorinated compounds, which do not meet increasingly stringent environmental protection requirements. Summary of the Invention

[0007] To address the problems existing in the prior art, the purpose of this invention is to provide a high-density composite fiber containing polyamide and its preparation method.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A high-density composite fiber containing polyamide is obtained by blending modified polyamide fiber and polyester fiber;

[0010] The modified polyamide fiber is obtained by melt spinning of modified polyamide;

[0011] The modified polyamide is prepared by reacting caprolactam and adipic acid under the action of a ring-opening agent to obtain a polyamide prepolymer; the polyamide prepolymer, modifier A and modifier B are reacted under the action of a catalyst to obtain the modified polyamide.

[0012] The modifier A is a vanillin Schiff base compound;

[0013] Modifier B is a vegetable oil-modified palm wax.

[0014] Preferably, the ring-opening agent is deionized water.

[0015] Preferably, the catalyst is composed of antimony glycolate and triphenyl phosphite in a weight ratio of 1:2.

[0016] Preferably, the mass ratio of caprolactam, ring-opening agent and adipic acid is 1-2:0.05-0.1:0.1-0.3.

[0017] Preferably, the mass ratio of caprolactam, catalyst, modifier A and modifier B is 1-2:0.01-0.02:0.1-0.3:0.2-0.4.

[0018] Preferably, the modified polyamide is prepared by: adding caprolactam, adipic acid, and a ring-opening agent into a nitrogen-protected high-pressure reactor and stirring; keeping the high-pressure reactor sealed; raising the temperature of the high-pressure reactor to 230-240°C and holding the reaction for 2-3 hours; evacuating the high-pressure reactor to remove water and obtaining a prepolymer; adding a catalyst, modifier A, and modifier B into the high-pressure reactor; sealing the reactor and introducing nitrogen; raising the pressure of the high-pressure reactor to 0.1-0.2 MPa; raising the temperature of the high-pressure reactor to 250-260°C and holding the reaction for 2-3 hours; and then performing post-treatment to obtain the modified polyamide.

[0019] The synthesis principle of modified polyamide is as follows: caprolactam and adipic acid are heated in a high-pressure reactor, and the amide group and carboxylic acid group undergo a condensation reaction to remove water molecules and form a polymer chain. Under the catalysis of the catalyst, modifier A and modifier B can undergo esterification reaction with the terminal carboxyl group of the prepolymer to further extend the polymer chain and obtain modified polyamide containing vanillin Schiff base compound and vegetable oil modified palm wax co-block.

[0020] Through the above technical solutions, the inventors discovered that, without modifying polyamide with fluorinated compounds, fabrics prepared using the polyamide-containing high-density composite fibers of this invention possess excellent waterproof and sun-protective properties as well as excellent wrinkle resistance. This may be attributed to the hydrophobic effect and UV resistance of the rigid aromatic ring in vanillin Schiff base compounds, as well as the hydrophobic and lubricating effects of long-chain fatty acid esters in vegetable oil-modified palm wax. In addition, unlike existing technologies, the polyamide-containing high-density composite fibers provided by this invention are designed to prepare high-density fabrics. These fabrics are finer, and high-density fabrics are characterized by high warp and weft density, a large total number of warp threads, numerous weaving points, and a dense fabric surface. Therefore, during the weaving process, problems such as unclear opening, tangled yarns, pilling, and broken yarns often occur. The lubricating effect of the vegetable oil-modified palm wax prepared by this invention precisely solves the above-mentioned technical problems.

[0021] Preferably, the post-processing method is as follows: after the reaction is completed, the temperature of the high-pressure reactor is reduced to 110-120°C, the material is discharged under vacuum and then crushed to obtain the final product.

[0022] Preferably, the modifier A is prepared by: first stirring and heating an anhydrous ethanol solution of vanillin, then adding an anhydrous ethanol solution of p-phenylenediamine dropwise; after the addition is complete, maintaining the temperature and stirring the reaction, and then removing the anhydrous ethanol to obtain the modifier A.

[0023] Preferably, the vanillin mass concentration in the anhydrous ethanol solution of vanillin is 5-10%.

[0024] Preferably, the mass concentration of the anhydrous ethanol solution of p-phenylenediamine is 5-10%.

[0025] Preferably, the molar ratio of vanillin to p-phenylenediamine is 1:1.

[0026] Preferably, the modifier A is prepared by: first stirring and heating an anhydrous ethanol solution of vanillin to 60-70°C, then adding an anhydrous ethanol solution of p-phenylenediamine dropwise. After the addition is complete, keep warm and stir for 1-3 hours, and then remove the anhydrous ethanol to obtain the modifier A.

[0027] The synthesis principle of modifier A is as follows: the aldehyde group of vanillin reacts with the amino group of p-phenylenediamine to form a Schiff base compound.

[0028] Preferably, the modifier B is prepared by mixing vegetable oil, palm wax, p-toluenesulfonic acid and 1,4-dioxane, heating and stirring under closed conditions, removing p-toluenesulfonic acid and 1,4-dioxane under reduced pressure, and washing until neutral to obtain the product.

[0029] The synthesis reaction principle of modifier B is as follows: the carboxylic acid in vegetable oil reacts with the fatty alcohol in palm wax through esterification to obtain vegetable oil modified palm wax.

[0030] Preferably, the vegetable oil is selected from at least one of soybean oil, castor oil, corn oil, and tung oil.

[0031] Preferably, the mass ratio of the vegetable oil, palm wax, p-toluenesulfonic acid, and 1,4-dioxane is 30-40:8-12:0.05-0.1:80-120.

[0032] Preferably, the modifier B is prepared by mixing vegetable oil, palm wax, p-toluenesulfonic acid and 1,4-dioxane, heating to 110-120°C under closed conditions and stirring for 5-8 hours, removing p-toluenesulfonic acid and 1,4-dioxane under reduced pressure, and washing until neutral to obtain the product.

[0033] Preferably, the modified polyamide fiber is prepared by placing dried modified polyamide in a screw extruder, melting and extruding it into a spinning machine, ejecting it through a spinneret, and stretching it to obtain modified polyamide fiber.

[0034] Preferably, the spinning machine has a spinning temperature of 270-290℃, a spinning speed of 1400-2000m, a draw ratio of 8-12 times, and a draw temperature of 120-130℃.

[0035] Preferably, the modified polyamide fiber has a fiber fineness of 5.0-7.0 dtex.

[0036] Preferably, the polyester fiber has a fiber fineness of 3.0-7.0 dtex.

[0037] Preferably, the mass ratio of the modified polyamide fiber to the polyester fiber is 6-8:2-4.

[0038] The present invention also provides a method for preparing polyamide-containing high-density composite fibers, comprising the following steps: uniformly mixing modified polyamide fibers and polyester fibers, spinning, and obtaining polyamide-containing high-density composite fibers.

[0039] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0040] This invention modifies a prepolymer prepared from caprolactam and adipic acid by using vanillin Schiff base compounds and vegetable oil-modified palm wax to obtain a modified polyamide containing co-blocks of vanillin Schiff base compounds and vegetable oil-modified palm wax. Even without fluorinated compounds, the fabric made from this polyamide high-density composite fiber still has excellent waterproof and sun protection properties as well as excellent wrinkle resistance. Furthermore, during the preparation of high-density fabric, issues such as unclear openings, tangled yarns, pilling, and broken yarns are less likely to occur. Attached Figure Description

[0041] Figure 1 This is a photograph of a fabric made from polyamide-containing high-density composite fibers prepared in Example 1. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Unless otherwise specified in the examples and comparative examples, the conditions were performed under standard conditions or conditions recommended by the manufacturer. All reagents and instruments used were commercially available products unless otherwise specified.

[0044] Example 1

[0045] A method for preparing a high-density composite fiber containing polyamide is as follows: modified polyamide fiber and polyester fiber are uniformly mixed at a mass ratio of 7:3 and spun to obtain a high-density composite fiber containing polyamide.

[0046] The polyester fiber has a fineness of 7.0 dtex and is sourced from Ningbo Zhuocheng Chemical Fiber Co., Ltd.

[0047] The modified polyamide fiber is prepared by placing dried modified polyamide in a screw extruder, melting and extruding it into a spinning machine, spraying it out through a spinneret, and stretching it to obtain polyamide fiber with a fiber fineness of 7.0 dtex.

[0048] The spinning machine has a spinning temperature of 290℃, a spinning speed of 1600m, a draw ratio of 10, and a draw temperature of 130℃.

[0049] The modified polyamide is prepared as follows: caprolactam, adipic acid, and a ring-opening agent are added to a nitrogen-protected high-pressure reactor and stirred. The high-pressure reactor is kept sealed, and the temperature of the high-pressure reactor is raised to 230°C and kept at this temperature for 2 hours. The high-pressure reactor is then evacuated to remove water, resulting in a prepolymer. A catalyst, modifier A, and modifier B are added to the high-pressure reactor. The reactor is then sealed and nitrogen is introduced. The pressure of the high-pressure reactor is raised to 0.1 MPa, and the temperature of the high-pressure reactor is raised to 250°C and kept at this temperature for 2 hours. After the reaction is complete, the temperature of the high-pressure reactor is lowered to 110°C, and the material is discharged under vacuum and pulverized to obtain the final product.

[0050] The ring-opening agent is deionized water.

[0051] The catalyst is composed of antimony glycolate and triphenyl phosphite in a weight ratio of 1:2.

[0052] The mass ratio of caprolactam, ring-opening agent, and adipic acid is 1.5:0.08:0.2.

[0053] The mass ratio of caprolactam, catalyst, modifier A and modifier B is 1.5:0.015:0.2:0.3.

[0054] The preparation method of the modifier A is as follows: first, stir and heat the anhydrous ethanol solution of vanillin to 70°C, then add anhydrous ethanol solution of p-phenylenediamine dropwise. After the addition is complete, keep warm and stir for 2 hours, and then remove the anhydrous ethanol to obtain the product.

[0055] The vanillin mass concentration in the anhydrous ethanol solution is 8%.

[0056] The mass concentration of the anhydrous ethanol solution of p-phenylenediamine is 8%.

[0057] The molar ratio of vanillin to p-phenylenediamine is 1:1.

[0058] The preparation method of the modifier B is as follows: vegetable oil, palm wax, p-toluenesulfonic acid and 1,4-dioxane are mixed, heated to 120°C under closed conditions and stirred for 6 hours, p-toluenesulfonic acid and 1,4-dioxane are removed by vacuum recovery, and the mixture is washed until neutral to obtain the final product.

[0059] The vegetable oil is castor oil.

[0060] The mass ratio of the vegetable oil, palm wax, p-toluenesulfonic acid, and 1,4-dioxane is 25:10:0.08:100.

[0061] Example 2

[0062] A method for preparing a high-density composite fiber containing polyamide is as follows: modified polyamide fiber and polyester fiber are uniformly mixed at a mass ratio of 7:3 and spun to obtain a high-density composite fiber containing polyamide.

[0063] The polyester fiber has a fineness of 7.0 dtex and is sourced from Ningbo Zhuocheng Chemical Fiber Co., Ltd.

[0064] The modified polyamide fiber is prepared by placing dried modified polyamide in a screw extruder, melting and extruding it into a spinning machine, spraying it out through a spinneret, and stretching it to obtain polyamide fiber with a fiber fineness of 7.0 dtex.

[0065] The spinning machine has a spinning temperature of 290℃, a spinning speed of 1600m, a draw ratio of 10, and a draw temperature of 130℃.

[0066] The modified polyamide is prepared as follows: caprolactam, adipic acid, and a ring-opening agent are added to a nitrogen-protected high-pressure reactor and stirred. The high-pressure reactor is kept sealed, and the temperature of the high-pressure reactor is raised to 230°C and kept at this temperature for 2 hours. The high-pressure reactor is then evacuated to remove water, resulting in a prepolymer. A catalyst, modifier A, and modifier B are added to the high-pressure reactor. The reactor is then sealed and nitrogen is introduced. The pressure of the high-pressure reactor is raised to 0.1 MPa, and the temperature of the high-pressure reactor is raised to 250°C and kept at this temperature for 2 hours. After the reaction is complete, the temperature of the high-pressure reactor is lowered to 110°C, and the material is discharged under vacuum and pulverized to obtain the final product.

[0067] The ring-opening agent is deionized water.

[0068] The catalyst is composed of antimony glycolate and triphenyl phosphite in a weight ratio of 1:2.

[0069] The mass ratio of caprolactam, ring-opening agent, and adipic acid is 2:0.1:0.3.

[0070] The mass ratio of caprolactam, catalyst, modifier A and modifier B is 1:0.01:0.1:0.4.

[0071] The preparation method of the modifier A is as follows: first, stir and heat the anhydrous ethanol solution of vanillin to 70°C, then add anhydrous ethanol solution of p-phenylenediamine dropwise. After the addition is complete, keep warm and stir for 2 hours, and then remove the anhydrous ethanol to obtain the product.

[0072] The vanillin mass concentration in the anhydrous ethanol solution is 8%.

[0073] The mass concentration of the anhydrous ethanol solution of p-phenylenediamine is 8%.

[0074] The molar ratio of vanillin to p-phenylenediamine is 1:1.

[0075] The preparation method of the modifier B is as follows: vegetable oil, palm wax, p-toluenesulfonic acid and 1,4-dioxane are mixed, heated to 120°C under closed conditions and stirred for 6 hours, p-toluenesulfonic acid and 1,4-dioxane are removed by vacuum recovery, and the mixture is washed until neutral to obtain the final product.

[0076] The vegetable oil is castor oil.

[0077] The mass ratio of the vegetable oil, palm wax, p-toluenesulfonic acid, and 1,4-dioxane is 25:10:0.08:100.

[0078] Example 3

[0079] A method for preparing a high-density composite fiber containing polyamide is as follows: modified polyamide fiber and polyester fiber are uniformly mixed at a mass ratio of 7:3 and spun to obtain a high-density composite fiber containing polyamide.

[0080] The polyester fiber has a fineness of 7.0 dtex and is sourced from Ningbo Zhuocheng Chemical Fiber Co., Ltd.

[0081] The modified polyamide fiber is prepared by placing dried modified polyamide in a screw extruder, melting and extruding it into a spinning machine, spraying it out through a spinneret, and stretching it to obtain polyamide fiber with a fiber fineness of 7.0 dtex.

[0082] The spinning machine has a spinning temperature of 290℃, a spinning speed of 1600m, a draw ratio of 10, and a draw temperature of 130℃.

[0083] The modified polyamide is prepared as follows: caprolactam, adipic acid, and a ring-opening agent are added to a nitrogen-protected high-pressure reactor and stirred. The high-pressure reactor is kept sealed, and the temperature of the high-pressure reactor is raised to 230°C and kept at this temperature for 2 hours. The high-pressure reactor is then evacuated to remove water, resulting in a prepolymer. A catalyst, modifier A, and modifier B are added to the high-pressure reactor. The reactor is then sealed and nitrogen is introduced. The pressure of the high-pressure reactor is raised to 0.1 MPa, and the temperature of the high-pressure reactor is raised to 250°C and kept at this temperature for 2 hours. After the reaction is complete, the temperature of the high-pressure reactor is lowered to 110°C, and the material is discharged under vacuum and pulverized to obtain the final product.

[0084] The ring-opening agent is deionized water.

[0085] The catalyst is composed of antimony glycolate and triphenyl phosphite in a weight ratio of 1:2.

[0086] The mass ratio of caprolactam, ring-opening agent, and adipic acid is 1:0.05:0.1.

[0087] The mass ratio of caprolactam, catalyst, modifier A and modifier B is 2:0.02:0.3:0.2.

[0088] The preparation method of the modifier A is as follows: first, stir and heat the anhydrous ethanol solution of vanillin to 70°C, then add anhydrous ethanol solution of p-phenylenediamine dropwise. After the addition is complete, keep warm and stir for 2 hours, and then remove the anhydrous ethanol to obtain the product.

[0089] The vanillin mass concentration in the anhydrous ethanol solution is 8%.

[0090] The mass concentration of the anhydrous ethanol solution of p-phenylenediamine is 8%.

[0091] The molar ratio of vanillin to p-phenylenediamine is 1:1.

[0092] The preparation method of the modifier B is as follows: vegetable oil, palm wax, p-toluenesulfonic acid and 1,4-dioxane are mixed, heated to 120°C under closed conditions and stirred for 6 hours, p-toluenesulfonic acid and 1,4-dioxane are removed by vacuum recovery, and the mixture is washed until neutral to obtain the final product.

[0093] The vegetable oil is castor oil.

[0094] The mass ratio of the vegetable oil, palm wax, p-toluenesulfonic acid, and 1,4-dioxane is 25:10:0.08:100.

[0095] Comparative Example 1

[0096] The only difference from Example 1 is that modifier A is replaced with an equal mass of modifier B; all other aspects are the same.

[0097] Comparative Example 2

[0098] The only difference from Example 1 is that modifier A is replaced with an equal mass of modified polysiloxane; the modified polysiloxane is the modified polysiloxane disclosed in Example 1 of Chinese Patent No. CN 118087087 B, and the preparation method is as follows: 13.2 g of allyl dimethoxysilane, 171.3 g of 1,7-dimethoxyoctamethyltetrasiloxane and 428 mL of anhydrous ethanol are added to a reaction vessel and stirred. The temperature of the reaction vessel is raised to 55°C, and 85.6 mL of 10 wt% sodium hydroxide solution is added to the reaction vessel. The reaction is kept at this temperature for 4 hours. After the reaction is complete, the ethanol is removed by vacuum distillation, the temperature of the reaction vessel is lowered to room temperature, 300 mL of purified water and 500 mL of dichloromethane are added to the reaction vessel, and the mixture is stirred at room temperature for 10 minutes. After standing and separation, the organic phase is washed twice with purified water and then transferred to a rotary evaporator with a water bath temperature of 45°C. The solvent is removed by vacuum distillation to obtain the modified polysiloxane; the rest is the same.

[0099] Comparative Example 3

[0100] The only difference from Example 1 is that modifier B is replaced with an equal mass of modifier A; all other aspects are the same.

[0101] Comparative Example 4

[0102] The only difference from Example 1 is that modifier B is replaced with an equal mass of modified polysiloxane; the modified polysiloxane is the modified polysiloxane disclosed in Example 1 of Chinese Patent No. CN 118087087 B, and the preparation method of the modified polysiloxane is the same as that of Comparative Example 2; all other aspects are the same.

[0103] Comparative Example 5

[0104] The only difference from Example 1 is that the preparation method of the modified polyamide is as follows: caprolactam, adipic acid, and a ring-opening agent are added to a nitrogen-protected high-pressure reactor and stirred. The high-pressure reactor is kept sealed, the temperature of the high-pressure reactor is raised to 230°C, and the reaction is maintained at this temperature for 2 hours. The high-pressure reactor is then evacuated to remove water, and a prepolymer is obtained. Epoxy castor oil (Zibo Kailian Chemical Co., Ltd., model: ESO-KLO1) and N,N-carbonyldiimidazole are added to the high-pressure reactor. The reactor is sealed and nitrogen is introduced. The pressure of the high-pressure reactor is raised to 0.1 MPa, the temperature of the high-pressure reactor is raised to 220°C, and the reaction is maintained at this temperature for 3 hours. After the reaction is completed, the temperature of the high-pressure reactor is lowered to 110°C, the material is discharged under vacuum, and then pulverized to obtain the final product. The mass ratio of caprolactam, epoxy castor oil, and N,N-carbonyldiimidazole is 10:1:0.02; all other parameters are the same.

[0105] Performance Testing: High-density fabrics with a warp and weft density of 782×646, woven from the polyamide-containing high-density composite fibers prepared in the above examples and comparative examples, were subjected to performance testing. A physical image of the fabric prepared using the polyamide-containing high-density composite fibers of Example 1 is shown below. Figure 1 As shown.

[0106] 1. Weaving performance: Observe whether there are any problems such as unclear opening, messy yarn, pilling, or broken yarn during the weaving process. If any of these problems are present, it is considered unqualified.

[0107] 2. Water resistance: (1) The surface moisture resistance level is tested according to standard GB / T 4745-2012;

[0108] (2) Refer to standard GB / T 32614-2023 "Outdoor Sports Clothing and Waterproof Jackets" 6.1.19 pressurization method: 6.0 kPa / min, water temperature: 20.0℃, test the hydrostatic pressure with the front facing down in contact with the water surface;

[0109] 3. Sun protection: The ultraviolet protection factor was determined in accordance with the standard GB / T 18830-2009 "Evaluation of Ultraviolet Protection Performance of Textiles";

[0110] 4. Wrinkle resistance: The wrinkle recovery angle is tested according to the standard GB / T 3819-1997 "Textiles - Determination of Crease Recovery - Recovery Angle Method".

[0111] Table 1

[0112]

[0113] Data Analysis:

[0114] By comparing and analyzing the data in Table 1 above, the polyamide-containing high-density composite fiber prepared by this invention has excellent weaving performance. During the weaving process, there are no problems such as unclear opening, tangled yarn, pilling, or broken yarn. The fabric prepared from the polyamide-containing high-density composite fiber has excellent water resistance: a moisture resistance rating of 4-5 and a hydrostatic pressure >170KPa; excellent UV resistance: UV protection factor >50; and excellent wrinkle resistance: wrinkle recovery angle >320°. The test data of each embodiment are generally better than those of the comparative example, indicating that by preparing vanillin Schiff base compounds and vegetable oil-modified palm wax to modify polyamide, this invention can effectively improve the water resistance, sun protection, and wrinkle resistance of polyamide fibers while making them suitable for the preparation of high-density fabrics.

[0115] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-density composite fiber containing polyamide, characterized in that, It is obtained by blending modified polyamide fibers and polyester fibers; The modified polyamide fiber is obtained by melt spinning of modified polyamide; The modified polyamide is prepared by reacting caprolactam and adipic acid under the action of a ring-opening agent to obtain a polyamide prepolymer; the polyamide prepolymer, modifier A and modifier B are reacted under the action of a catalyst to obtain the modified polyamide. The modifier A is a vanillin Schiff base compound; Modifier B is a vegetable oil-modified palm wax.

2. The polyamide-containing high-density composite fiber according to claim 1, characterized in that, The modified polyamide is prepared as follows: caprolactam, adipic acid, and a ring-opening agent are added to a nitrogen-protected high-pressure reactor and stirred. The high-pressure reactor is kept sealed, and the temperature of the high-pressure reactor is raised to 230-240℃. The reaction is maintained at this temperature for 2-3 hours. The high-pressure reactor is then evacuated to remove water, resulting in a prepolymer. A catalyst, modifier A, and modifier B are added to the high-pressure reactor. The reactor is then sealed and nitrogen is introduced. The pressure of the high-pressure reactor is raised to 0.1-0.2 MPa, and the temperature of the high-pressure reactor is raised to 250-260℃. The reaction is maintained at this temperature for 2-3 hours. The modified polyamide is then obtained through post-treatment.

3. The polyamide-containing high-density composite fiber according to claim 1 or 2, characterized in that, The modifier A is prepared by first stirring and heating an anhydrous ethanol solution of vanillin, then adding an anhydrous ethanol solution of p-phenylenediamine dropwise. After the addition is complete, the mixture is kept warm and stirred to react, and the anhydrous ethanol is removed to obtain the modifier A.

4. The polyamide-containing high-density composite fiber according to claim 1 or 2, characterized in that, The preparation method of the modifier B is as follows: vegetable oil, palm wax, p-toluenesulfonic acid and 1,4-dioxane are mixed, heated and stirred under closed conditions, p-toluenesulfonic acid and 1,4-dioxane are removed by vacuum recovery, and the mixture is washed until neutral to obtain the final product.

5. The polyamide-containing high-density composite fiber according to claim 4, characterized in that, The vegetable oil is selected from at least one of soybean oil, castor oil, corn oil, and tung oil.

6. The polyamide-containing high-density composite fiber according to claim 5, characterized in that, The mass ratio of the vegetable oil, palm wax, p-toluenesulfonic acid, and 1,4-dioxane is 30-40:8-12:0.05-0.1:80-120.

7. The polyamide-containing high-density composite fiber according to claim 1, characterized in that, The modified polyamide fiber is prepared by placing dried modified polyamide in a screw extruder, melting and extruding it into a spinning machine, spraying it out through a spinneret, and stretching it to obtain modified polyamide fiber.

8. The polyamide-containing high-density composite fiber according to claim 7, characterized in that, The modified polyamide fiber has a fiber fineness of 5.0-7.0 dtex; the polyester fiber has a fiber fineness of 3.0-7.0 dtex.

9. The polyamide-containing high-density composite fiber according to claim 8, characterized in that, The mass ratio of the modified polyamide fiber to the polyester fiber is 6-8:2-4.

10. The method for preparing polyamide-containing high-density composite fibers according to any one of claims 1-9, characterized in that, The process includes the following steps: uniformly mixing modified polyamide fibers and polyester fibers, spinning them, and obtaining high-density composite fibers containing polyamide.

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