Fluorine-free waterproof auxiliary agent for high-density polyester fabric and preparation method of fluoride-free waterproof auxiliary agent

Abstract

The invention relates to the technical field of polyester fiber products, and discloses a fluoride-free waterproof auxiliary agent for a high-density polyester fabric and a preparation method of the fluoride-free waterproof auxiliary agent. Comprising the following raw materials in parts by weight: 15-55 parts of long-chain alkyl waterborne polyurethane, 10-20 parts of a blocked isocyanate cross-linking agent, 1-3 parts of a nonionic low-foam penetrant, 0.5-1.5 parts of ethylenediamine propyl imidazoline, 1.5-2.2 parts of a KH-570 silane coupling agent and 1-3 parts of a polyol cross-linking accelerator, wherein the long-chain alkyl waterborne polyurethane is waterborne polyurethane resin in which C12-C18 long-chain alkyl is introduced for hydrophobic modification. The fluoride-free waterproof auxiliary agent can form a tightly-combined waterproof film on a fabric, and has both waterproof performance and durability.

Description

Technical Field

[0001] This invention relates to the field of polyester fiber products technology, and in particular to a fluorine-free waterproofing agent for high-density polyester fabrics and its preparation method. Background Technology

[0002] High-density polyester fabrics, due to their high strength, abrasion resistance, lightweight, and ease of molding, are widely used in clothing, bags, tents, down jackets, and other fields. These applications place high demands on the fabric's waterproof performance and washability. Traditional waterproofing treatments for polyester fabrics often employ fluorinated waterproofing agents, relying on the low surface energy of fluorocarbon chains to achieve excellent waterproofing. However, fluorinated waterproofing agents contain perfluorinated and polyfluoroalkyl substances (PFAS), which are environmentally persistent, bioaccumulative, and have been proven to pose health risks such as hepatotoxicity and reproductive toxicity. They have been included in the elimination list of the Stockholm Convention on Persistent Organic Pollutants, and are strictly prohibited under the EU REACH regulation. my country also prohibits the production and use of PFAS except for specific exemptions. The application of fluorinated waterproofing agents has been comprehensively restricted, making the development of fluorine-free, environmentally friendly waterproofing finishing systems a growing industry trend.

[0003] Currently, various fluorine-free waterproofing additives have emerged in existing technologies, such as long-chain alkyl compounds, polyurethane compounds, and polyolefin compounds. Although they can meet the basic requirements for fluorine-free environmental protection, due to the tight arrangement of fibers and low surface polarity of high-density polyester fabrics, fluorine-free waterproofing additives tend to float on the surface of the fabric. The waterproof film formed is only physically adsorbed and bound, making it difficult to balance waterproof performance and durability. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a fluorine-free waterproofing agent for high-density polyester fabrics, which can form a tightly bonded waterproof membrane on the fabric, balancing waterproof performance and durability.

[0005] The specific technical solution of the present invention is as follows: a fluorine-free waterproofing agent for high-density polyester fabrics, comprising the following raw materials by weight: 15-55 parts of long-chain alkyl waterborne polyurethane, 10-20 parts of blocked isocyanate crosslinking agent, 1-3 parts of nonionic low-foaming penetrant, 0.5-1.5 parts of ethylenediaminopropylimidazoline, 1.5-2.2 parts of KH-570 silane coupling agent, and 1-3 parts of polyol crosslinking accelerator, wherein the long-chain alkyl waterborne polyurethane is a waterborne polyurethane resin with C12-C18 long-chain alkyl groups introduced for hydrophobic modification.

[0006] The mechanism of action of the above-mentioned fluorine-free waterproofing additives is as follows: KH-570 silane coupling agent can hydrolyze to generate silanol groups, which undergo dehydration condensation with the hydroxyl groups on the surface of polyester fibers, forming a chemical anchor on the fiber surface and achieving surface activation, thereby improving the interfacial compatibility and reactivity between the fiber and subsequent resins. The imidazoline ring and active amino group in ethylenediaminepropylimidazoline can bond with the hydroxyl and amino groups on the long-chain alkyl waterborne polyurethane molecules. On the one hand, it introduces the imidazoline ring as a novel active site on the polyurethane molecular chain, enhancing its reactivity; on the other hand, it activates the original active groups of polyurethane, allowing a single polyurethane molecule to simultaneously bind with multiple crosslinking agents and fiber surface activation sites, significantly improving the utilization rate and bonding density of effective adhesion sites. Based on this, the -NCO groups released by the closed isocyanate crosslinking agent after thermal desealing can undergo crosslinking reactions with fiber activation sites, polyurethane molecules, and polyol crosslinking accelerators. The polyol crosslinking accelerators further enhance the crosslinking density through their multi-hydroxyl structure, resulting in a denser and more stable crosslinking network. The nonionic low-foaming penetrant reduces the surface tension of the system, allowing it to quickly penetrate the fiber gaps of high-density polyester fabrics. This enables the activator, waterproofing agent, and crosslinking agent to uniformly penetrate into the inner layer of the fiber, achieving simultaneous activation and interfacial bonding of the inner fiber layer. Ultimately, under the synergistic effect of all components, this fluorine-free waterproofing agent forms a four-dimensional crosslinking network structure of "fiber-activator-waterproofing agent-crosslinking agent" with the fiber. The components are anchored at multiple points and interlocked with each other, resulting in significantly better interfacial bonding than conventional fluorine-free waterproofing systems. This leads to the formation of a continuous, dense, and firmly bonded waterproof membrane on the fabric, achieving both excellent waterproof performance and high durability without the use of fluorine compounds.

[0007] Optionally, by weight, it may also include 2 to 3 parts of KH-550 silane coupling agent.

[0008] In the above technical solution, the addition of KH-550 silane coupling agent can further increase the number of chemical bonds and the density of interfacial anchor points between the fiber and resin system on the basis of the original four-dimensional cross-linked network, forming a denser and stronger interfacial bond, thereby significantly improving the overall interfacial bonding strength and durability.

[0009] Optionally, by weight, it may also include 4 to 5 parts of nonionic fabric softener.

[0010] In the above technical solution, the addition of nonionic softener can improve the feel of the fabric and at the same time avoid the adhesion and peeling caused by the brittleness of the waterproof membrane.

[0011] Optionally, the nonionic softener is a polyether-modified silicone emulsion.

[0012] Optionally, it may also include 0.5 to 1.5 parts by weight of an acidity regulator.

[0013] In the above technical solution, the addition of an acid regulator can adjust the fluorine-free waterproofing agent system to acidity, which can stabilize the emulsion system and activate the activity of crosslinking agents and activators, thereby promoting the full reaction of each adhesion site.

[0014] Optionally, the acidity regulator is glacial acetic acid.

[0015] Optionally, the polyol crosslinking accelerator is glycerol polyoxyethylene ether, and the nonionic low-foaming penetrant is isomeric alcohol polyoxyethylene ether.

[0016] Optionally, the mass ratio of the long-chain alkyl waterborne polyurethane to ethylenediaminepropylimidazoline is (30~35):1.

[0017] Another specific technical solution of the present invention is: a method for preparing a fluorine-free waterproofing agent for high-density polyester fabrics, comprising the following steps: S1: First, add ethylenediaminopropylimidazoline to an acidic aqueous solution and mix to obtain an activation solution. Then, add long-chain alkyl aqueous polyurethane to the activation solution and perform an activation reaction to obtain an activated modified waterproofing agent solution. S2: Add KH-570 silane coupling agent solution to the activated modified waterproofing agent solution and mix. Then add nonionic low-foaming penetrant, polyol crosslinking promoter, KH-550 silane coupling agent and nonionic softener, and mix to obtain composite modified liquid. S3: Add a blocked isocyanate crosslinking agent to the composite modified liquid and mix to obtain a fluorine-free waterproofing agent working liquid.

[0018] In the above preparation method, ethylenediaminopropylimidazoline is the primary activator. It needs to be protonated and activated in an acidic aqueous solution to form a positively charged active group before the long-chain alkyl waterborne polyurethane is added to ensure the stable dispersion of the main waterproof component. If the order is reversed, it will cause local pH mutation, causing the long-chain alkyl waterborne polyurethane to demulsify and flocculate. At the same time, the activator cannot be fully protonated in a stable acidic environment.

[0019] Optionally, in step S1, the preparation process of the acidic aqueous solution is as follows: an acidic regulator is added to the aqueous solution to adjust the pH value of the system to 5.5~6.5.

[0020] Optionally, in step S1, the activation reaction temperature is 20~30℃ and the reaction time is 15~30min.

[0021] Optionally, in step S2, the KH-570 silane coupling agent solution is prepared by diluting KH-570 silane coupling agent with water at a mass ratio of 1:(4~6).

[0022] The fluorine-free waterproofing agent of this invention is applied to the waterproofing finishing of high-density polyester fabrics in the form of a working solution. The method of use is as follows: The high-density polyester fabric is fed into the padding tank and immersed in the fluorine-free waterproofing agent working solution. The speed is 28~35m / min, the padding rate is 58%~65%, and the padding pressure is 0.2~0.3Mpa. The padded fabric is then sent to a dryer for pre-drying. The pre-drying temperature is 105~115℃, and the drying time is 4~8 minutes, which is adjusted according to the fabric thickness to ensure that the surface moisture of the fabric is completely dried. The pre-dried fabric is then sent to a setting machine for high-temperature baking. The baking temperature is 175~185℃, and the baking time is 80~100 seconds. The baked fabric is then sent to a cooling zone and cooled to room temperature to obtain a waterproof fabric.

[0023] During the padding stage, the fabric carries sufficient fluorine-free waterproofing agents. The working solution fully penetrates the inner layer and surface of the high-density polyester fibers, completing physical adhesion and basic molecular contact with the fibers. After a pre-drying process at 105-115℃, the surface moisture of the fabric is thoroughly removed, allowing the waterproofing agent, activator, and crosslinking agent to spread evenly on the fiber surface. The KH-570 silane coupling agent further hydrolyzes to generate sufficient silanol groups, which complete preliminary dehydration condensation with the hydroxyl groups on the surface of the polyester fibers. Then, it enters a high-temperature baking stage at 175-185℃. The blocked isocyanate crosslinking agent is deactivated by heat, releasing -NCO active groups, which initiate crosslinking reactions with various active sites in the system. Simultaneously, the KH-570 silane coupling agent... Under these high-temperature conditions, the acryloyloxy group in the fiber opens its double bond to form an active free radical, which completes a dehydration condensation reaction with the hydroxyl groups on the fiber surface. This forms a stable chemical anchor on the fiber surface and achieves complete surface activation, significantly improving the interfacial compatibility and reactivity between the fiber and the waterproof resin. It also adds a large number of double bond active sites to the fiber end. The KH-550 aminosilane coupling agent simultaneously condenses with the activated hydroxyl groups of the fiber and combines with the active groups of the crosslinking agent and the waterproofing agent. Together with KH-570, it constructs a dual attachment site. Finally, with -NCO as the core crosslinking link, the active sites at the fiber end and the active sites at the modified auxiliary agent end are bonded at multiple points and interlocked with each other to form a four-dimensional crosslinked network structure.

[0024] Compared with the prior art, the present invention has at least the following advantages: The present invention breaks through the traditional physical adsorption binding method of fluorine-free waterproofing agents. By dual activation of the auxiliary agent end and the fiber end, the system forms a four-dimensional cross-linked network structure of "fiber-activator-waterproofing agent-cross-linking agent" at the fiber interface, thereby forming a continuous, dense and firmly bonded waterproof membrane on the fabric. Thus, without using fluorine compounds, it achieves excellent waterproof performance and high durability at the same time. Detailed Implementation

[0025] The present invention will now be described through specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of the inventive concept are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0026] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used in this invention are conventional in the art and can be obtained through conventional commercial means; unless otherwise specified, the methods used in this invention are conventional methods in the art.

[0027] In the embodiments of this invention, the long-chain alkyl waterborne polyurethane used is Covestro PUD waterborne polyurethane, the ethylenediaminepropylimidazoline is obtained by the condensation and dehydration reaction of C8-C18 fatty acids and diethylenetriamine, and the remaining raw materials are conventional commercially available products in the field of waterproof finishing of polyester fabrics.

[0028] Example 1: This invention provides a fluorine-free waterproofing agent for high-density polyester fabrics, comprising the following raw materials: 30 parts long-chain alkyl waterborne polyurethane, 13 parts blocked isocyanate crosslinking agent, 2 parts isomeric alcohol polyoxyethylene ether, 0.9 parts ethylenediaminopropylimidazoline, 1.8 parts KH-570 silane coupling agent, 2 parts glycerol polyoxyethylene ether, 2.2 parts KH-550 silane coupling agent, 4.5 parts polyether-modified silicone emulsion, and 0.9 parts glacial acetic acid.

[0029] The preparation method of the above-mentioned fluorine-free waterproofing agent includes the following steps: S1: Slowly add 0.9g of glacial acetic acid to a mixing tank containing 700ml of deionized water to adjust the pH of the system to 6. Add 0.9g of ethylenediaminopropylimidazoline to the acidic aqueous solution, stir for 4 minutes, and then turn on a 200W ultrasonic disperser to disperse for 3 minutes to obtain an activated solution. Add 30g of long-chain alkyl waterborne polyurethane to the activated solution to carry out the activation reaction. The reaction temperature is 25℃, and the mixture is stirred for 6 minutes while maintaining 150W ultrasonic dispersion throughout. After stirring, turn off the ultrasonic and let it stand for 12 minutes. After the reaction is completed, the activated modified waterproofing agent solution is obtained. S2: Dilute 1.8g of KH-570 silane coupling agent with deionized water at a mass ratio of 1:5 to prepare a KH-570 silane coupling agent solution. Add the KH-570 silane coupling agent solution to the activated modified waterproofing agent solution and mix. Stir for 5 minutes to ensure that the KH-570 silane coupling agent is evenly dispersed and initially hydrolyzed. Then, add 2.0g of isomeric alcohol polyoxyethylene ether, 2.0g of glycerol polyoxyethylene ether, 2.2g of KH-550 silane coupling agent and 4.5g of polyether modified organosilicon emulsion in sequence, and keep stirring throughout the process to obtain a composite modified liquid. S3: Add 13g of blocked isocyanate crosslinking agent to the composite modified liquid and stir for 5 minutes to obtain the fluorine-free waterproofing agent working liquid.

[0030] To avoid the risk of premature cross-linking of the system, step S3 is performed 10-15 minutes before the machine is started.

[0031] Example 2: This invention provides a fluorine-free waterproofing agent for high-density polyester fabrics, comprising the following raw materials: 15 parts long-chain alkyl waterborne polyurethane, 10 parts blocked isocyanate crosslinking agent, 1 part isomeric alcohol polyoxyethylene ether, 0.5 parts ethylenediaminopropylimidazoline, 1.5 parts KH-570 silane coupling agent, 2 parts glycerol polyoxyethylene ether, 2 parts KH-550 silane coupling agent, 4 parts polyether-modified silicone emulsion, and 0.5 parts glacial acetic acid.

[0032] The preparation method of the above-mentioned fluorine-free waterproofing agent includes the following steps: S1: Slowly add 0.5g of glacial acetic acid to a mixing tank containing 700ml of deionized water to adjust the pH of the system to 6.5. Add 0.5g of ethylenediaminopropylimidazoline to the acidic aqueous solution, stir for 4 minutes, and then turn on a 200W ultrasonic disperser to disperse for 3 minutes to obtain an activated solution. Add 15g of long-chain alkyl waterborne polyurethane to the activated solution to carry out the activation reaction. The reaction temperature is 20℃, and the mixture is stirred for 10 minutes while maintaining 150W ultrasonic dispersion throughout. After stirring, turn off the ultrasonic and let it stand for 10 minutes. After the reaction is completed, the activated modified waterproofing agent solution is obtained. S2: Dilute 1.5g of KH-570 silane coupling agent with deionized water at a mass ratio of 1:4 to prepare a KH-570 silane coupling agent solution. Add the KH-570 silane coupling agent solution to the activated modified waterproofing agent solution and mix. Stir for 5 minutes to ensure that the KH-570 silane coupling agent is evenly dispersed and initially hydrolyzed. Then add 1.0g of isomeric alcohol polyoxyethylene ether, 2.0g of glycerol polyoxyethylene ether, 2g of KH-550 silane coupling agent and 4g of polyether modified organosilicon emulsion in sequence, and keep stirring throughout the process to obtain a composite modified liquid. S3: Add 10g of blocked isocyanate crosslinking agent to the composite modified liquid and stir for 5 minutes to obtain the fluorine-free waterproofing agent working liquid.

[0033] To avoid the risk of premature cross-linking of the system, step S3 is performed 10-15 minutes before the machine is started.

[0034] Example 3: This invention provides a fluorine-free waterproofing agent for high-density polyester fabrics, comprising the following raw materials: 55 parts long-chain alkyl waterborne polyurethane, 20 parts blocked isocyanate crosslinking agent, 3 parts isomeric alcohol polyoxyethylene ether, 1.5 parts ethylenediaminopropylimidazoline, 2.2 parts KH-570 silane coupling agent, 3 parts glycerol polyoxyethylene ether, 3 parts KH-550 silane coupling agent, 5 parts polyether-modified silicone emulsion, and 1.2 parts glacial acetic acid.

[0035] The preparation method of the above-mentioned fluorine-free waterproofing agent includes the following steps: S1: Slowly add 1.2g of glacial acetic acid to a mixing tank containing 700ml of deionized water to adjust the pH of the system to 6.5. Add 1.5g of ethylenediaminopropylimidazoline to the acidic aqueous solution, stir for 4 minutes, and then turn on a 200W ultrasonic disperser to disperse for 3 minutes to obtain an activated solution. Add 55g of long-chain alkyl waterborne polyurethane to the activated solution to carry out the activation reaction. The reaction temperature is 30℃, and the mixture is stirred for 10 minutes while maintaining 150W ultrasonic dispersion throughout. After stirring, turn off the ultrasonic and let it stand for 20 minutes. After the reaction is completed, the activated modified waterproofing agent solution is obtained. S2: Dilute 2.2g of KH-570 silane coupling agent with deionized water at a mass ratio of 1:6 to prepare a KH-570 silane coupling agent solution. Add the KH-570 silane coupling agent solution to the activated modified waterproofing agent solution and mix. Stir for 5 minutes to ensure that the KH-570 silane coupling agent is evenly dispersed and initially hydrolyzed. Then add 3.0g of isomeric alcohol polyoxyethylene ether, 3.0g of glycerol polyoxyethylene ether, 3g of KH-550 silane coupling agent and 5g of polyether modified organosilicon emulsion in sequence, and keep stirring throughout the process to obtain a composite modified liquid. S3: Add 20g of blocked isocyanate crosslinking agent to the composite modification liquid and stir for 5 minutes to obtain the fluorine-free waterproofing agent working liquid.

[0036] To avoid the risk of premature cross-linking of the system, step S3 is performed 10-15 minutes before the machine is started.

[0037] The fluorine-free waterproofing agent working solution prepared in Example 1 was applied to the waterproofing finishing of high-density polyester fabric. The specific process is as follows: A 20cm×20cm piece of high-density polyester fabric was placed into the padding tank and immersed in the fluorine-free waterproofing agent working solution. The padding speed was controlled at 30m / min, the padding pressure at 0.25MPa, and the padding rate was controlled at 60%. The padded fabric was quickly sent to the dryer and pre-dried at 110℃ for 30s. Then the fabric was sent to the setting machine and baked at 180℃ for 90 seconds. After the baking was completed, the fabric was taken out and allowed to cool naturally to room temperature to obtain a test sample of high-density polyester waterproof fabric.

[0038] The waterproof performance and durability of the high-density polyester waterproof fabric sample were tested. The testing standard followed AATCC 22, with 250 mL of deionized water sprayed vertically onto the sample surface over 25 seconds. The test results showed no water residue or wetting on the fabric surface, achieving a rating of 100 points, and the water droplets exhibited good roll-off properties. After 50 standard washes, the waterproof rating remained above 90 points. These results indicate that the fluorine-free waterproofing agent prepared in this invention forms a waterproof film on high-density polyester fabric with excellent initial waterproof performance, good wash resistance, and long-lasting waterproof effect.

[0039] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A fluorine-free waterproofing agent for high-density polyester fabrics, characterized in that, By weight, it comprises the following raw materials: 15-55 parts long-chain alkyl waterborne polyurethane, 10-20 parts blocked isocyanate crosslinking agent, 1-3 parts nonionic low-foaming penetrant, 0.5-1.5 parts ethylenediaminopropylimidazoline, 1.5-2.2 parts KH-570 silane coupling agent, and 1-3 parts polyol crosslinking accelerator, wherein the long-chain alkyl waterborne polyurethane is a waterborne polyurethane resin with C12-C18 long-chain alkyl groups introduced for hydrophobic modification.

2. The fluorine-free waterproofing agent for high-density polyester fabrics according to claim 1, characterized in that, It also includes 2 to 3 parts by weight of KH-550 silane coupling agent.

3. The fluorine-free waterproofing agent for high-density polyester fabrics according to claim 1, characterized in that, It also includes 4 to 5 parts by weight of nonionic softener.

4. The fluorine-free waterproofing agent for high-density polyester fabrics according to claim 1, characterized in that, It also includes 0.5 to 1.5 parts by weight of acid regulator.

5. A fluorine-free waterproofing agent for high-density polyester fabrics according to claim 1, characterized in that, The polyol crosslinking accelerator is glycerol polyoxyethylene ether, and the nonionic low-foaming penetrant is isomeric alcohol polyoxyethylene ether.

6. A fluorine-free waterproofing agent for high-density polyester fabrics according to any one of claims 1 to 5, characterized in that, The mass ratio of the long-chain alkyl waterborne polyurethane to ethylenediaminepropylimidazoline is (30~35):

1.

7. A method for preparing a fluorine-free waterproofing agent for high-density polyester fabrics, characterized in that, Includes the following steps: S1: First, add ethylenediaminopropylimidazoline to an acidic aqueous solution and mix to obtain an activation solution. Then, add long-chain alkyl aqueous polyurethane to the activation solution and perform an activation reaction to obtain an activated modified waterproofing agent solution. S2: Add KH-570 silane coupling agent solution to the activated modified waterproofing agent solution and mix. Then add nonionic low-foaming penetrant, polyol crosslinking promoter, KH-550 silane coupling agent and nonionic softener, and mix to obtain composite modified liquid. S3: Add a blocked isocyanate crosslinking agent to the composite modified liquid and mix to obtain a fluorine-free waterproofing agent working liquid.

8. A method for preparing a fluorine-free waterproofing agent for high-density polyester fabrics according to claim 7, characterized in that, In step S1, the preparation process of the acidic aqueous solution is as follows: an acidic regulator is added to the aqueous solution to adjust the pH value of the system to 5.5~6.

5.

9. A method for preparing a fluorine-free waterproofing agent for high-density polyester fabrics according to claim 7, characterized in that, In step S1, the activation reaction temperature is 20~30℃ and the reaction time is 15~30min.

10. A method for preparing a fluorine-free waterproofing agent for high-density polyester fabrics according to claim 7, characterized in that, In step S3, the KH-570 silane coupling agent solution is prepared by diluting KH-570 silane coupling agent and water at a mass ratio of 1:(4~6).