Polyacrylate fluoride-free waterproof agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of textile chemical assistants, in particular to a polyacrylate fluoride-free waterproof agent as well as a preparation method and application thereof. The invention provides a polyacrylate fluoride-free waterproof agent which comprises the following components in parts by weight: 7-11 parts of a hard monomer, 81-85 parts of a hydrophobic acrylate monomer, 3-7 parts of a crosslinking monomer, 1-5 parts of a functional monomer, 4-8 parts of a compound emulsifier, 26-30 parts of a cosolvent, 0.4-0.8 part of an initiator and 400-430 parts of water, the compound emulsifier comprises hexadecyl trimethyl ammonium chloride and allyloxy polyoxyethylene ether with the molecular weight of 800 to 1000 Da. According to the invention, allyloxy polyoxyethylene ether and polyacrylate are polymerized and then grafted with a polyoxyethylene ether chain segment, so that the bonding strength of the polyacrylate fluoride-free waterproof agent and fibers can be enhanced, and excellent durability is achieved; by controlling the length of a polyoxyethylene ether chain segment, the arrangement direction and position of a hydrophobic chain are relatively controlled, so that excellent waterproofness is achieved.

Description

A fluorine-free polyacrylate waterproofing agent, its preparation method and application Technical Field

[0001] This invention relates to the field of textile chemical auxiliaries technology, specifically to a polyacrylate-based fluorine-free waterproofing agent, its preparation method, and its application. Background Technology

[0002] Waterproofing finishing of textiles, as a key branch of functional finishing, has received considerable attention in the textile industry in recent years. With the rise of outdoor sports and the increasing demand for functional textiles, the importance of waterproofing finishing has become increasingly prominent. For a long time, fluorinated waterproofing agents have dominated the market due to their superior water and oil repellency. However, research shows that long-chain fluorocarbons (such as C8) are difficult to degrade in the environment and have bioaccumulation and potential biotoxicity, posing a threat to the ecological environment and human health. With increasingly stringent environmental regulations (such as the EU PFOA ban), the development of high-performance fluorinated-free waterproofing agents has become an urgent need for the industry.

[0003] Currently, fluorine-free waterproofing agents on the market are mainly divided into paraffin-metal salts, silicones, and polyacrylates. Paraffin-based products have a hard feel and poor durability; silicone-based products have a soft feel, but their waterproofing effect, especially their hydrostatic pressure resistance, is usually inferior to fluorine-containing products. Fluorine-free polyacrylate waterproofing agents, through molecular design, can introduce long-chain alkyl groups to simulate the low surface tension characteristics of fluorocarbon chains, showing potential for lower cost and better environmental performance. However, existing fluorine-free polyacrylate waterproofing agents generally suffer from insufficient durability (water resistance, abrasion resistance), a hard feel, or poor emulsion stability; and the waterproofing performance of ordinary fluorine-free waterproofing agents cannot meet the high demands of the market.

[0004] Therefore, developing a fluorine-free polyacrylate waterproofing agent that combines high-efficiency waterproofing, water resistance, and environmental friendliness has significant practical importance and market value. Summary of the Invention

[0005] This invention provides a fluorine-free polyacrylate-based waterproofing agent, its preparation method, and its application. The invention uses methyl methacrylate as a hard monomer, octadecyl acrylate as a hydrophobic monomer, and introduces N-hydroxymethylacrylamide and hydroxyethyl acrylate as crosslinking functional monomers. A polymer emulsion is prepared via a semi-continuous seed emulsion polymerization method. Through innovative compounding of emulsifiers, specifically hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether, this invention significantly improves the product's wash resistance while ensuring excellent waterproofing. This waterproofing agent is fluorine-free and suitable for environmentally friendly finishing of textiles.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a polyacrylate-based fluorine-free waterproofing agent, comprising, by weight: 7-11 parts hard monomer, 81-85 parts hydrophobic acrylate monomer, 3-7 parts crosslinking monomer, 1-5 parts functional monomer, 4-8 parts composite emulsifier, 26-30 parts cosolvent, 0.4-0.8 parts initiator, and 400-430 parts water; wherein the composite emulsifier comprises hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether with a molecular weight of 800-1000 Da.

[0007] This invention, in addition to conventional polyacrylate formulations, utilizes a blend of two emulsifiers to significantly enhance the water resistance and durability of polyacrylate while stabilizing the polyacrylate emulsion. Hexadecyltrimethylammonium chloride, a common long-chain cationic emulsifier, carries a positive charge, making the polyacrylate emulsion positively charged. This allows for spontaneous adsorption onto the negatively charged fiber surface, achieving a strong bond between the polyacrylate emulsion and the fiber surface. Allyloxy polyoxyethylene ether, unlike typical nonionic emulsifiers, possesses double bonds and can react with polyacrylate to graft a polyoxyethylene ether segment onto the polyacrylate. This gives the polyacrylate-based fluorine-free waterproofing agent provided by this invention a polyoxyethylene ether segment, which offers two advantages: firstly, the polyoxyethylene ether segment itself is hydrophilic, allowing for dehydration condensation with the hydroxyl groups on the fiber during the baking stage, further strengthening the interaction between the polyacrylate-based fluorine-free waterproofing agent and the fiber surface. Secondly, when the polyoxyethylene ether segments combine with the fiber due to their hydrophilic properties, the position of the hydrophobic chains brought by the hydrophobic acrylate monomers is also relatively fixed. When the hydrophilic segments face the fiber side, the hydrophobic chains face away from the fiber side. In this way, the hydrophobic chains with hydrophobic effects can be arranged as far outward as possible, which can achieve a better waterproof effect.

[0008] However, during the exploratory phase, the inventors discovered that although the position of the hydrophobic chain could be controlled after fixing the hydrophilic segment, the waterproofing effect still did not reach the ideal state. Furthermore, the inventors found that the length of the hydrophilic segment affects the arrangement of the hydrophobic chain. When the molecular weight of the allyloxy polyoxyethylene ether is controlled at 800~1000 Da, the length of the introduced polyoxyethylene ether segment has a more effective control effect on the direction of the hydrophobic chain arrangement, and can better meet the waterproofing requirements.

[0009] Ultimately, this invention provides a polyacrylate-based fluorine-free waterproofing agent that utilizes hexadecyltrimethylammonium chloride and allyloxyethylene ether with a molecular weight of 800-1000 Da as composite emulsifiers. By grafting polyoxyethylene ether segments onto the polymerized polyacrylate, the bonding strength between the polyacrylate-based fluorine-free waterproofing agent and the fiber can be strengthened, thereby achieving excellent durability. By controlling the length of the polyoxyethylene ether segments, the arrangement direction and position of the hydrophobic chains can be relatively controlled, thereby achieving excellent waterproofing.

[0010] Preferably, the mass ratio between the hexadecyltrimethylammonium chloride and the allyloxy polyoxyethylene ether with a molecular weight of 800-1000 Da is 1:(1.5-2.5).

[0011] Both hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether possess amphiphilic properties, helping to balance the hydrophobic and hydrophilic groups in the emulsion, ensuring emulsion stability and preventing microphase separation. Their combination also hinders latex particle collisions and gelation, ensuring a smooth polymerization reaction. Therefore, the ratio of the composite emulsifier significantly impacts the performance of fluorine-free polyacrylate waterproofing agents, affecting monomer conversion during polymerization and the stability of the polyacrylate emulsion. Furthermore, an inappropriate ratio can lead to a rapid increase in the particle size of fluorine-free polyacrylate waterproofing agents and a decrease in stability, resulting in a decline in overall waterproof performance and durability. This may be related to the amount of polyoxyethylene ether segments introduced; insufficient polyoxyethylene ether segments weaken the bonding between the fluorine-free polyacrylate waterproofing agent and the fiber surface, leading to a more significant decline in durability. When there is an excessive amount of polyoxyethylene ether segments, the number of hydroxyl groups on the fiber is limited. In addition to the polyoxyethylene ether segments, crosslinking functional monomers such as N-hydroxymethylacrylamide and hydroxyethyl acrylate can also introduce hydrophilic hydroxymethyl and hydroxyl groups into polyacrylate-based fluorine-free waterproofing agents. Therefore, an excessive amount of polyoxyethylene ether segments is actually detrimental to the arrangement of hydrophobic chains, resulting in a decrease in waterproofing performance. Furthermore, an excessive amount of polyoxyethylene ether segments will significantly increase the particle size of polyacrylate-based fluorine-free waterproofing agents, leading to decreased stability and hindering the effective performance of waterproofing.

[0012] Preferably, the pH of the polyacrylate-based fluorine-free waterproofing agent is 4.5 to 6.0.

[0013] Allyloxy polyoxyethylene ether breaks its double bonds and reacts with polyacrylate, grafting hydrophilic polyoxyethylene ether segments onto the polyacrylate. Under weakly acidic conditions, the reaction between the hydrophilic polyoxyethylene ether segments and the hydroxyl groups on the fiber is accelerated during the baking stage (160~180℃), allowing the hydrophilic groups to be quickly fixed in position and the hydrophobic chains to rapidly orient outwards, thus improving the waterproofing performance of the fluorine-free waterproofing agent. Simultaneously, the dehydration condensation reaction between the polyoxyethylene ether segments and the hydroxyl groups on the fiber results in a stronger bond between the fluorine-free waterproofing agent and the fiber, further enhancing its durability.

[0014] Preferably, the hard monomer is at least one of methyl methacrylate, tert-butyl methacrylate, and styrene.

[0015] Preferably, the hydrophobic acrylate monomer is at least one of octadecyl acrylate, octadecyl methacrylate, and hexadecyl acrylate.

[0016] Preferably, the crosslinking monomer is at least one of N-hydroxymethylacrylamide, N-methoxymethylacrylamide, and glycidyl methacrylate; and / or, the functional monomer is at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxybutyl acrylate.

[0017] Preferably, the cosolvent is isopropanol or ethanol; and / or, the initiator is potassium persulfate, ammonium persulfate or sodium persulfate.

[0018] Methyl methacrylate, as a hard monomer, provides rigid support for the polymer backbone, giving the film excellent durability. Octadecyl acrylate, with its long-chain alkyl structure, can significantly reduce the surface energy of the polymer film, thus giving the fabric excellent hydrophobic properties. The hydroxymethyl group of the N-hydroxymethylacrylamide side chain can covalently cross-link with the hydroxyl groups in the cellulose molecules on the fabric surface during film formation, significantly improving the wash fastness of the finished fabric. Hydroxyethyl acrylate, while participating in the copolymerization reaction, introduces active sites for further reaction through its side hydroxyl groups, which not only promotes the densification of the cross-linked network inside the film but also enhances the chemical bonding with the fiber interface, thereby synergistically improving the durability and stability of the finishing effect.

[0019] This invention also provides a method for preparing a polyacrylate-based fluorine-free waterproofing agent, comprising: S1. Preparing pre-emulsion A: mixing 0.4~0.6g hard monomer, 19.0~20.0g hydrophobic acrylate monomer, 0.9~1.1g crosslinking monomer, 0.9~1.1g functional monomer, 0.9~1.1g composite emulsifier, 3~5g cosolvent with 65~75mL water, homogenizing and emulsifying to obtain pre-emulsion A; S2. Preparing pre-emulsion B: mixing 2.4~2.6g hard monomer, 7.3~7.7g hydrophobic acrylate monomer, 0.6~0.7g crosslinking monomer, 0.45~0.55g composite emulsifier, 2.5~3.5g cosolvent with 33~37mL water, homogenizing and emulsifying to obtain pre-emulsion B; S3. Preparing solution C: mixing 0.45~0.51g composite emulsifier with 65~75mL water, homogenizing and emulsifying to obtain pre-emulsion B; S4. Preparation of solution D: Mix 0.18-0.22g of initiator with 9-11mL of water to obtain solution D; S5. Seed emulsion preparation and polymerization: Add solution C to the reactor, heat to 72-78℃ and stir for 25-35min; then add 6.5-7.5g of pre-emulsion A, stir for 4-6min, and then add 1.8-2.2g of solution D; S6. Semi-continuous dropwise polymerization: Add the remaining pre-emulsion A, all pre-emulsion B and the remaining solution D to the reactor at a uniform rate over 2.0-3.0h. After the addition is complete, continue the reaction at 72-78℃ for 3.5-4.5h, add acid to adjust the pH to 4.5-6.0, and the polyacrylate-based fluorine-free waterproofing agent is obtained.

[0020] In the seed emulsion polymerization process, a composite emulsifier system is used as the initial reaction medium, and a portion of pre-emulsion A (rich in hydrophobic acrylate monomers) is added as seed monomers to form "seed" latex particles under the action of an initiator. At this stage, the proportion of hydrophobic acrylate monomers is relatively high, laying the foundation for the subsequent construction of a highly hydrophobic core layer or compositional gradient structure. Subsequently, the remaining pre-emulsion A and pre-emulsion B (with an increased proportion of hard monomers and a correspondingly decreased proportion of hydrophobic monomers) are simultaneously and slowly added dropwise to the reaction system along with the initiator solution, guiding the polymer chain composition to gradually evolve from the inside out during growth: the internal hydrophobic segments are enriched, while the proportion of rigid segments in the outer layer gradually increases. This gradient structure promotes the migration and orderly arrangement of internal hydrophobic long-chain alkyl groups to the film surface during film formation, forming a low surface energy layer; simultaneously, the higher external glass transition temperature helps to lock this hydrophobic arrangement structure, thereby endowing the textile with durable waterproof properties.

[0021] This invention also provides the application of polyacrylate-based fluorine-free waterproofing agents in waterproof finishing of textiles.

[0022] The present invention also provides a method for waterproof finishing, wherein the fabric is immersed in a finishing solution containing 50-70 g / L of the polyacrylate-based fluorine-free waterproofing agent, subjected to two dips and two nips, with a nip-off rate of 60-80%, then pre-dried at 70-90°C for 1-5 min, and then baked at 160-180°C for 1-3 min.

[0023] The present invention has the following beneficial effects: (1) The present invention uses allyloxy polyoxyethylene ether with a molecular weight of 800~1000 Da as a co-emulsifier. After the allyloxy polyoxyethylene ether is polymerized with polyacrylate, the polyoxyethylene ether segments grafted on it can strengthen the bonding strength between the polyacrylate-based fluorine-free waterproofing agent and the fiber, thereby achieving excellent durability. By controlling the length of the polyoxyethylene ether segments, the arrangement direction and position of the hydrophobic chain can be relatively controlled, thereby achieving excellent waterproofing.

[0024] (2) The present invention utilizes hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether to greatly enhance the water resistance and durability of polyacrylate at a specific mass ratio; and hexadecyltrimethylammonium chloride imparts positive charge to the emulsion, which binds tightly to the negatively charged fiber surface through electrostatic adsorption, and works together with the polyoxyethylene ether segments to enhance durability.

[0025] (3) This invention regulates the polyacrylate-based fluorine-free waterproofing agent to a weakly acidic environment. The weak acid catalyzes the reaction between the polyoxyethylene ether segments and the hydroxyl groups on the fiber during the baking stage (160~180℃), rapidly fixing the positions of the hydrophilic groups and causing the hydrophobic chains to quickly orient outwards, thus improving the waterproofing performance of the fluorine-free waterproofing agent. Simultaneously, the dehydration condensation reaction between the polyoxyethylene ether segments and the hydroxyl groups on the fiber strengthens the bond between the fluorine-free waterproofing agent and the fiber, further enhancing the durability of the fluorine-free waterproofing agent.

[0026] (4) In this invention, methyl methacrylate is used as a hard monomer, octadecyl acrylate is used as a hydrophobic monomer, and N-hydroxymethylacrylamide and hydroxyethyl acrylate are introduced as crosslinking functional monomers. N-hydroxymethylacrylamide can undergo self-crosslinking during baking at 160~180℃ and can also react with the hydroxyl groups on the fiber surface to form a stable three-dimensional network structure, which significantly improves the wash resistance and abrasion resistance of the fabric; the hydroxyl groups of hydroxyethyl acrylate can enhance the affinity with the fiber and participate in the crosslinking reaction, further improving the durability of the finishing layer.

[0027] (5) This invention employs seed emulsion polymerization technology, which is simple to implement and produces an emulsion with excellent storage stability. This waterproofing agent has nano-sized particles and monodispersity, allowing it to penetrate deeply into the gaps between textile fibers to form a dense, uniform hydrophobic film, thereby significantly improving waterproofing efficiency. Furthermore, the waterproofing agent is fluoride-free, environmentally friendly, and leaves the finished fabric soft, smooth, and without stiffness. Attached Figure Description

[0028] Figure 1 shows the infrared spectrum of the emulsion polymer, a-N-hydroxymethylacrylamide; b-hydroxyethyl acrylate; c-methyl methacrylate; d-octadecyl acrylate; e-Example 1.

[0029] Figure 2 shows the XPS spectrum of Example 1.

[0030] Figure 3 shows the SEM images of the untreated polyester fabric (a) and the polyester fabric treated with the waterproofing process of Example 1 (b). Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0032] The main raw materials used in this section are as follows: methyl methacrylate, octadecyl acrylate, N-hydroxymethylacrylamide, hydroxyethyl acrylate, sodium dodecyl sulfate, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, nonylphenol polyoxyethylene ether, polyethylene glycol methacrylate, and isopropanol were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and allyloxy polyoxyethylene ethers of 700 Da, 1000 Da, and 2000 Da were all purchased from Haian Petrochemical Plant in Jiangsu Province.

[0033]

Example

[0034] 2.5 g methyl methacrylate, 7.5 g octadecyl acrylate, 0.65 g N-hydroxymethylacrylamide, 0.16 g cetyltrimethylammonium chloride, 0.32 g 1000 Da allyloxyethylene ether, 3 g isopropanol and 35 mL water were added to a beaker and homogenized using a homogenizer to obtain preemulsion B.

[0035] 0.16 g of hexadecyltrimethylammonium chloride, 0.32 g of 1000 Da allyloxy polyoxyethylene ether, 2 g of isopropanol and 20 mL of water were added to a beaker to obtain solution C.

[0036] Add 0.2 g of potassium persulfate and 10 mL of water to a beaker to obtain solution D.

[0037] Use two syringes, one 50 mL and the other 10 mL, to draw 50 mL of pre-emulsion A, pre-emulsion B, and solution D respectively. Then use a 50 mL syringe to draw the remaining pre-emulsion A.

[0038] After preparation, solution C was first added to a three-necked flask equipped with a constant temperature stirring device and a reflux condenser, and stirred at 75°C for 30 min. After stirring, 7.18 g of preemulsion A was added, and the mixture was stirred for 5 min. Then, 2 g of solution D was added to initiate the reaction. Finally, using a micro-injection pump, the remaining preemulsion A, all of preemulsion B, and the remaining solution D were injected into the flask over 2.5 h. After injection, the reaction was allowed to continue for 4 h. Hydrochloric acid was added to adjust the pH to 5.5, yielding a fluorine-free polyacrylate waterproofing agent.

[0039] Example 2 This example is basically the same as Example 1, except that hydrochloric acid is not added to adjust the pH.

[0040] Comparative Example 1 is basically the same as Example 1, except that the addition of allyloxy polyoxyethylene ether is omitted in the composite emulsifier.

[0041] Comparative Example 2 is basically the same as Example 1, except that: hexadecyltrimethylammonium chloride in the composite emulsifier is replaced with an equal mass of sodium dodecyl sulfate.

[0042] Comparative Example 3 is basically the same as Example 1, except that: hexadecyltrimethylammonium chloride in the composite emulsifier is replaced with an equal mass of dodecyltrimethylammonium chloride.

[0043] Comparative Example 4 is basically the same as Example 1, except that: hexadecyltrimethylammonium chloride in the composite emulsifier is replaced with an equal mass of octadecyltrimethylammonium chloride.

[0044] Comparative Example 5 is basically the same as Example 1, except that the allyloxy polyoxyethylene ether in the composite emulsifier is replaced with an equal mass of nonylphenol polyoxyethylene ether.

[0045] Comparative Example 6 is basically the same as Example 1, except that the allyloxy polyoxyethylene ether in the composite emulsifier is replaced with an equal mass of polyethylene glycol methacrylate.

[0046] Comparative Example 7 is basically the same as Example 1, except that: in the composite emulsifier, hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether are compounded in a mass ratio of 2:1.

[0047] Comparative Example 8 is basically the same as Example 1, except that: in the composite emulsifier, hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether are compounded in a mass ratio of 1:1.

[0048] Comparative Example 9 is basically the same as Example 1, except that: in the composite emulsifier, hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether are compounded in a mass ratio of 3:1.

[0049] Comparative Example 10 is basically the same as Example 1, except that: in the composite emulsifier, hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether are compounded in a mass ratio of 1:3.

[0050] Comparative Example 11 is basically the same as Example 1, except that the 1000 Da allyloxy polyoxyethylene ether is replaced with an equal mass of 700 Da allyloxy polyoxyethylene ether.

[0051] Comparative Example 12 is basically the same as Example 1, except that 1000 Da allyloxy polyoxyethylene ether is replaced with an equal mass of 2000 Da allyloxy polyoxyethylene ether.

[0052] [Performance Testing] Contact Angle Test: The textile was made of polyester fabric. The waterproofing agent prepared in Examples 1-2 and Comparative Examples 1-12 was treated with a waterproofing process (the fabric was immersed in a finishing solution containing 60g / L of waterproofing agent, dipped and rubbed twice, with a pick-up rate of 60%-70%, then pre-dried at 80℃ for 3 minutes, and then baked at 170℃ for 100 seconds). The water contact angle (static) was tested according to DB44 / T1872-2016 "Determination of Wetting Properties of Textile Surfaces - Contact Angle Method".

[0053] Waterproof performance test: The textile was made of polyester fabric. The waterproofing agent prepared in Examples 1-2 and Comparative Examples 1-12 was treated with a waterproofing process (the fabric was immersed in a finishing solution containing 60g / L of waterproofing agent, dipped and rubbed twice, with a pick-up rate of 60%-70%, then pre-dried at 80°C for 3 minutes, and then baked at 170°C for 100 seconds). The waterproof performance was tested according to AATCC 22-2014 "Water repellency test: spray test".

[0054] Contact angle test after 20 washes: The textile was made of polyester fabric. The waterproofing agent prepared in Examples 1-2 and Comparative Examples 1-12 was applied to the fabric using a waterproofing process (the fabric was immersed in a finishing solution containing 60 g / L of waterproofing agent, dipped and rubbed twice, with a pick-up rate of 60%-70%, then pre-dried at 80°C for 3 minutes, and then baked at 170°C for 100 seconds). The fabric was then tumble-washed with water at 40°C for 15 minutes, tumble-dried, and the washing was repeated 20 times. After 20 washes, the contact angle was tested according to the contact angle test method.

[0055] 1. Structural Characterization: The waterproofing agent prepared in Example 1 was subjected to infrared spectroscopy testing, and the results are shown in Figure 1. As shown in Figure 1, the structure is located at 1631 cm⁻¹. -1 The absorption peak of the C=C double bond stretching vibration (usually corresponding to unsaturated bonds in acrylate or olefin monomers) in the near-field electron microscopy spectrum is significantly weaker than that in the a, b, c, and d spectra. This indicates that the four monomers containing C=C functional groups in the system were largely consumed during the polymerization process and fully participated in the copolymerization reaction, demonstrating the successful synthesis of the polyacrylate-based fluorine-free waterproofing agent. Furthermore, at 722 cm⁻¹... -1 The peak at 1070 cm⁻¹ corresponds to the absorption vibration of long-chain alkanes, indicating that octadecyl acrylate participated in the polymerization reaction. -1 The peak at 1665 cm⁻¹ is a characteristic peak of the COC ether bond, consistent with the aliphatic ether structural unit in the allyloxy polyoxyethylene ether structure, indicating that the monomer has been successfully integrated into the polyacrylate backbone. -1 The characteristic peak at 2850 cm⁻¹ indicates that N-hydroxymethylacrylamide participated in the polymerization reaction, suggesting that the amide group was involved. -1 and 2920 cm -1 The two absorption peaks correspond to the symmetric and asymmetric stretching vibrations of the methylene group, respectively, indicating that a long-chain alkane structure has been introduced into the polyacrylate-based fluorine-free waterproofing agent, forming a rich methylene skeleton.

[0056] The waterproofing agent prepared in Example 1 was subjected to XPS testing, and the results are shown in Figure 2. Its main elemental composition is carbon and oxygen, and it also contains nitrogen and O1. S N1 S C1 S They are located near 532 eV, 402 eV, and 285 eV, respectively.

[0057] The surface morphology of the polyester fabrics before and after treatment was characterized using scanning electron microscopy, and the results are shown in Figure 3. As can be seen from Figure 3, the fiber surface of the untreated sample is clearly exposed, showing its inherent texture and obvious gaps; after the waterproof treatment in Example 1, the fibers are uniformly covered by a continuous and dense latex film, indicating that polyacrylate has successfully formed a complete film layer on the fabric surface.

[0058] 2. Waterproofing Performance Based on the above characterization of the film-forming effect on polyester fabrics, it can be inferred that the polyacrylate-based fluorine-free waterproofing agent provided by the present invention has good waterproofing performance. Furthermore, the waterproofing performance of the waterproofing agents prepared in Examples 1-2 and Comparative Examples 1-12 was verified, and the results are shown in Table 1.

[0059] Table 1 Performance test results of different waterproofing agents

[0060] The infrared results in Figure 1 show that allyloxy polyoxyethylene ether reacts with polyacrylate, grafting polyoxyethylene ether segments onto the polyacrylate. As shown in Table 1 (Comparative Example 1 and Example 1), the polyoxyethylene ether segments significantly increase the particle size of the polyacrylate emulsion. This is consistent with the infrared results indicating the reaction between allyloxy polyoxyethylene ether and polyacrylate. However, the absence of allyloxy polyoxyethylene ether and the introduction of polyoxyethylene ether segments significantly reduces the waterproofing performance of the polyacrylate-based fluorine-free waterproofing agent. Furthermore, the durability also slightly decreases after 20 washes, compared to the decrease in contact angle. It is speculated that after the polyoxyethylene ether segments, acting as hydrophilic segments, bond with the fiber surface, the position of the C18 hydrophobic chain of octadecyl acrylate becomes relatively fixed, and the polyoxyethylene ether segments play a crucial role in the directional arrangement of the C18 hydrophobic chains, thus causing a significant change in waterproofing performance.

[0061] Furthermore, in Comparative Examples 7-10, only the ratio of hexadecyltrimethylammonium chloride to allyloxy polyoxyethylene ether was adjusted, resulting in a significant decrease in stability and a corresponding significant deterioration in waterproofing performance. This indicates that an inappropriate compounding ratio can cause a rapid increase in the particle size of fluorine-free polyacrylate waterproofing agents and a decrease in stability, leading to a decline in overall waterproofing performance and durability. It is speculated that this may be related to the amount of polyoxyethylene ether segments introduced. Insufficient polyoxyethylene ether segments weaken the bonding between the fluorine-free polyacrylate waterproofing agent and the fiber surface, resulting in a more significant decline in durability. Conversely, excessive polyoxyethylene ether segments limit the number of hydroxyl groups on the fiber. In addition to polyoxyethylene ether segments, crosslinking functional monomers such as N-hydroxymethylacrylamide and hydroxyethyl acrylate also introduce hydrophilic hydroxymethyl and hydroxyl groups into the fluorine-free polyacrylate waterproofing agent. Therefore, excessive polyoxyethylene ether segments are actually detrimental to the arrangement of hydrophobic chains, resulting in a decrease in waterproofing performance. Furthermore, excessive polyoxyethylene ether segments significantly increase the particle size of fluorine-free polyacrylate waterproofing agents, leading to decreased stability, which is detrimental to waterproofing performance. Meanwhile, comparing the solid content and monomer conversion rate of the emulsion at different mass ratios (Table 2) revealed a non-monotonic trend of "increase-decrease-increase-decrease" as the proportion of allyloxy polyoxyethylene ether increases. When the mass ratio of hexadecyltrimethylammonium chloride to allyloxy polyoxyethylene ether was 1:2 (Example 1), both reached their peak values ​​(solid content 16.53%, monomer conversion rate 80.03%). These results demonstrate the importance of the compound emulsifier formulation ratio.

[0062] Table 2. Effect of different ratios of hexadecyltrimethylammonium chloride to allyloxypolyoxyethylene ether on the reaction.

[0063] The molecular weight of allyloxy polyoxyethylene ether has a more critical impact on water resistance, demonstrating that the length of the polyoxyethylene ether segment has the greatest influence on the orientation of the C18 hydrophobic chains. Results from Comparative Examples 11-12 and Example 1 show that when the molecular weight of allyloxy polyoxyethylene ether is controlled within the range of 800-1000 Da, the relative length of the introduced polyoxyethylene ether segment better controls the orientation of the hydrophobic chains, meeting water resistance requirements. Under weakly acidic conditions, the hydrophilic polyoxyethylene ether segments react more rapidly with the hydroxyl groups on the fiber during the baking stage (170°C), quickly fixing the positions of the hydrophilic groups and causing the hydrophobic chains to oriented outwards, thus improving the water resistance of the fluorine-free waterproofing agent. Simultaneously, the dehydration condensation reaction between the polyoxyethylene ether segments and the hydroxyl groups on the fiber strengthens the bond between the fluorine-free waterproofing agent and the fiber, further enhancing its durability. Therefore, the combination of weak acid and allyloxy polyoxyethylene ether can further improve the water resistance and durability of the waterproofing agent, as demonstrated in the data from Examples 1 and 2. When acidity adjustment was removed, the waterproof performance of Example 2 decreased slightly compared to Example 1, demonstrating that controlling the weak acid environment can further improve the waterproofness and durability of the waterproofing agent.

Claims

1. A fluorine-free polyacrylate waterproofing agent, characterized in that, By weight, it comprises: 7-11 parts hard monomer, 81-85 parts hydrophobic acrylate monomer, 3-7 parts crosslinking monomer, 1-5 parts functional monomer, 4-8 parts composite emulsifier, 26-30 parts cosolvent, 0.4-0.8 parts initiator, and 400-430 parts water; the composite emulsifier comprises hexadecyltrimethylammonium chloride and allyloxy polyoxyethylene ether with a molecular weight of 800-1000 Da.

2. The polyacrylate-based fluorine-free waterproofing agent as described in claim 1, characterized in that, The mass ratio between the hexadecyltrimethylammonium chloride and the allyloxy polyoxyethylene ether with a molecular weight of 800-1000 Da is 1:(1.5-2.5).

3. The polyacrylate-based fluorine-free waterproofing agent as described in claim 1 or 2, characterized in that, The pH of the polyacrylate-based fluorine-free waterproofing agent is 4.5~6.

0.

4. The polyacrylate-based fluorine-free waterproofing agent as described in claim 1, characterized in that, The hard monomer is at least one of methyl methacrylate, tert-butyl methacrylate, and styrene.

5. The polyacrylate-based fluorine-free waterproofing agent as described in claim 1, characterized in that, The hydrophobic acrylate monomer is at least one of octadecyl acrylate, octadecyl methacrylate, and hexadecyl acrylate.

6. The polyacrylate-based fluorine-free waterproofing agent as described in claim 1, characterized in that, The crosslinking monomer is at least one of N-hydroxymethylacrylamide, N-methoxymethylacrylamide, and glycidyl methacrylate; and / or, the functional monomer is at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxybutyl acrylate.

7. The polyacrylate-based fluorine-free waterproofing agent as described in claim 1, characterized in that, The cosolvent is isopropanol or ethanol; and / or the initiator is potassium persulfate, ammonium persulfate or sodium persulfate.

8. A method for preparing a polyacrylate-based fluorine-free waterproofing agent as described in any one of claims 1 to 7, characterized in that, include: S1. Preparation of preemulsion A: Mix 0.4~0.6g hard monomer, 19.0~20.0g hydrophobic acrylate monomer, 0.9~1.1g crosslinking monomer, 0.9~1.1g functional monomer, 0.9~1.1g composite emulsifier, 3~5g cosolvent with 65~75mL water, and homogenize emulsify to obtain preemulsion A; S2. Preparation of preemulsion B: Mix 2.4~2.6g hard monomer, 7.3~7.7g hydrophobic acrylate monomer, 0.6~0.7g crosslinking monomer, 0.45~0.55g composite emulsifier, 2.5~3.5g cosolvent with 33~37mL water, and homogenize emulsify to obtain preemulsion B; S3. Preparation of solution C: Mix 0.45~0.51g composite emulsifier, 1.5~2.5g cosolvent with 18~22mL water to obtain solution C; S4. Preparation of solution D: Mix 0.18~0.22g of initiator with 9~11mL of water to obtain solution D; S5. Seed emulsion preparation and polymerization: Add solution C to the reactor, heat to 72~78℃ and stir for 25~35min; then add 6.5~7.5g of pre-emulsion A, stir for 4~6min, and then add 1.8~2.2g of solution D; S6. Semi-continuous dropwise polymerization: Add the remaining pre-emulsion A, all pre-emulsion B and the remaining solution D to the reactor at a uniform rate over 2.0~3.0h. After the addition is complete, continue the reaction at 72~78℃ for 3.5~4.5h, add acid to adjust the pH to 4.5~6.0, and the polyacrylate-based fluorine-free waterproofing agent is obtained.

9. The application of the polyacrylate-based fluorine-free waterproofing agent as described in any one of claims 1 to 7 in the waterproofing finishing of textiles.

10. A method for waterproof finishing, characterized in that, Using the polyacrylate-based fluorine-free waterproofing agent as described in any one of claims 1 to 7; the fabric is immersed in a finishing solution containing 50 to 70 g / L of the polyacrylate-based fluorine-free waterproofing agent, subjected to two dips and two nips, with a nip-off rate of 60 to 80%, then pre-dried at 70 to 90°C for 1 to 5 min, and then baked at 160 to 180°C for 1 to 3 min.

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