Preparation method of an aqueous polyurethane-acrylate adhesive for fabric lamination

Abstract

The present invention provides a preparation method of an aqueous polyurethane-acrylate adhesive for fabric lamination, belonging to the technical field of adhesive preparation. In the present invention, a polyurethane prepolymer is synthesized from an aliphatic polycarbonate-polyether polyol, a hydrophilic chain extender and an isocyanate, and then partially blocked with a hydroxyacrylate monomer. After salification with a neutralizing agent, low-temperature chain extension with a post-chain extender and seed emulsion polymerization, an aqueous polyurethane-acrylate emulsion with a core-shell structure is generated. By selecting the types of polyurethane-acrylate monomers and optimizing the ratio of the chain segments, the synthesized composite adhesive has pressure sensitivity and provides initial strength. During the later use process, through crosslinking with a curing agent, the bonding strength and wash resistance of the composite fabric are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesive preparation, and particularly relates to a preparation method of a waterborne polyurethane-acrylate adhesive for fabric lamination. Background Art

[0002] Polyurethane has received extensive attention due to its excellent properties, and the global restrictions on volatile solvents have promoted the development and utilization of waterborne polyurethane. Waterborne polyurethane uses water as the dispersion medium, and has the advantages of low toxicity, non-flammability, low pollution, energy saving, safety, etc. It has a clearer development prospect compared with solvent-based polyurethanes. However, waterborne polyurethane has disadvantages such as slow drying, low initial adhesion, and poor water washing resistance. Especially for textile composite fabrics, higher requirements are placed on water washing resistance. Therefore, many scholars have done a lot of work on the modification of waterborne polyurethane emulsions, among which the comprehensive performance of waterborne acrylate-modified polyurethane emulsions is better.

[0003] The most typical modification methods are physical blending modification and copolymerization modification. The physical mixing method is relatively simple. The invention patent CN201610718198.6 discloses a preparation method of a carbon dioxide-based waterborne polyurethane-polyacrylate composite emulsion and its composite coating. The coating prepared by this technology is a transparent waterborne polyurethane-acrylate coating, but the two are only mixed in the form of an interpenetrating network structure, and the mechanical properties are not significantly improved and the stability of the system is poor. The invention patent of CN103059230B discloses a modified waterborne polyurethane. First, waterborne polyurethane is prepared, and then styrene and acrylic acid are used to modify the waterborne polyurethane dispersion to obtain an acrylic acid-modified waterborne polyurethane with an interpenetrating network structure. The interpenetrating network forms a topological bond rather than a true covalent bond, which belongs to physical modification. Compared with the physical modification method, the chemical copolymerization method has great advantages in solving the compatibility of PU and PA and improving the comprehensive performance of the emulsion. The invention patents with the publication number CN101906192B both provide a preparation method of a waterborne polyurethane-acrylate composite emulsion, in which an unsaturated polyurethane monomer with a double bond and an acrylate monomer are copolymerized, without the need to add an external solvent and emulsifier. However, there are problems such as a long reaction time, a low grafting rate of polyurethane and acrylate monomers, easy retention of residual monomers, and a low solid content of the product.

[0004] Therefore, it is urgent to develop a new type of environmentally friendly and high-performance waterborne polyurethane adhesive. Summary of the Invention

[0005] The object of the present invention is to address the above problems existing in the prior art and propose a preparation method of a waterborne polyurethane-acrylate adhesive for fabric lamination.

[0006] The object of the present invention can be achieved by the following technical solutions: A preparation method of an aqueous polyurethane-acrylate adhesive for fabric lamination, comprising the following steps: S1 Preparation of an aqueous polyurethane prepolymer: S1.1 Dehydration pretreatment: Aliphatic polycarbonate-polyether polyol PPCD, non-ionic polyol N120, hydrophilic chain extender and antioxidant are mixed evenly and then dehydrated to obtain a dehydrated mixture; the hydrophilic chain extender is DMPA or DMBA; S1.2 Isocyanate polycondensation reaction: After cooling the dehydrated mixture, isocyanate is added to the dehydrated mixture for polycondensation reaction to obtain a mixture after isocyanate polycondensation reaction; the isocyanate is specifically one of IPDI, hydrogenated MDI, MDI-50 and HDI; S1.3 Partial capping reaction: After cooling the mixture after isocyanate polycondensation reaction, hydroxyacrylate monomer is added to the mixture after isocyanate polycondensation reaction for partial capping reaction. After the reaction ends, a mixture after partial capping reaction is obtained; the hydroxyacrylate monomer is specifically HEA monomer or HPA monomer; S1.4 Salt formation: After cooling the mixture after partial capping reaction, a neutralizing agent and a viscosity regulator are added to the mixture after partial capping reaction for salt formation reaction to obtain a mixture after salt formation reaction; the neutralizing agent is triethylamine; S1.5 High-speed dispersion: After cooling the mixture after salt formation reaction, it is placed in a cold water bath device, then deionized water is added, and then high-speed dispersion treatment is carried out to obtain an initial dispersion mixture; S1.6 Post-chain extender dropping: An aqueous solution of a post-chain extender is dropped into the initial dispersion mixture for reaction to obtain an initial target mixture; the post-chain extender is ethylenediamine; S1.7 Post-treatment: The initial target mixture is subjected to high-speed dispersion treatment. After the dispersion ends, filtration operation and removal of the viscosity regulator operation are carried out in sequence to obtain an aqueous polyurethane prepolymer;

[0007] S2 Synthesis of an aqueous polyurethane-acrylate emulsion: S2.1 Polymerization reaction: The aqueous polyurethane prepolymer, a partial acrylate monomer mixture, a chain initiator and deionized water are mixed evenly and then subjected to a polymerization reaction; after the reaction ends, the remaining acrylate monomer mixture is added dropwise and the polymerization reaction is continued. After the reaction ends, a polymerization reaction mixture is obtained; the acrylate monomer mixture includes ethyl acrylate, isooctyl acrylate, n-butyl acrylate and hydroxyacrylate; the chain initiator is azobisisobutyronitrile; S2.2 Additives addition: After cooling the mixture after polymerization reaction, a defoaming agent and a leveling agent are added, and then stirring operation is carried out. After stirring until uniform, an aqueous polyurethane-acrylate adhesive is obtained.

[0008] Preferably, in step S1, the antioxidant is antioxidant 1010; the viscosity regulator is acetone.

[0009] Preferably, in step S1, by weight ratio, aliphatic polycarbonate-polyether polyol PPCD: non-ionic polyol N120: hydrophilic chain extender: isocyanate: antioxidant 1010: hydroxyacrylate monomer: neutralizing agent: post-chain extender is 65-80:1-5:2-5:20-30:0.1-0.5:2-5:1-3:1-3; the amount of deionized water used is 2-2.4 times the sum of the weights of aliphatic polycarbonate-polyether polyol PPCD, non-ionic polyol N120, hydrophilic chain extender, isocyanate, antioxidant 1010, hydroxyacrylate monomer, neutralizing agent and post-chain extender.

[0010] In the operation of removing the viscosity regulator, acetone is removed by means of vacuum distillation.

[0011] In the aqueous solution of the post-chain extender, the concentration of ethylenediamine is 50%.

[0012] Preferably, in step S2.1, by weight ratio, partial acrylate monomer mixture: remaining acrylate monomer mixture is 1:2.

[0013] Preferably, in step S1.1, the dehydration operation is carried out under vacuum conditions, the temperature of the dehydration operation is 110-120 °C, and the water content in the dehydration mixture is less than 300 ppm.

[0014] Preferably, in step S1.2, the target temperature of the cooling operation is below 60 °C, and the polycondensation reaction temperature is 100-110 °C; in step S1.3, the target temperature of the cooling operation is 80 °C, and the partial capping reaction temperature is 80 °C; in step S1.4, the target temperature of the cooling operation is 55-60 °C, and the salt formation reaction temperature is 55-60 °C; in step S1.5, the target temperature of the cooling operation is not higher than 30 °C, and the temperature of the cold water in the cold water bath device is 5-15 °C; in step S2.1, the polymerization reaction temperature is 80-85 °C; in step S2.2, the target temperature of the cooling operation is below 40 °C.

[0015] Preferably, the leveling agent is specifically one of Tego410 type leveling agent, Tego425 type leveling agent and Runhe T1008 type leveling agent; the defoaming agent is specifically one of 810S type defoaming agent and BYK-024 type defoaming agent.

[0016] By weight ratio, aqueous polyurethane prepolymer: ethyl acrylate: isooctyl acrylate: n-butyl acrylate: hydroxyacrylate: chain initiator: defoaming agent: leveling agent: deionized water is 100:10-15:1-3:3-6:1-3:0.05-1:0.05-1:0.05-1:35-50.

[0017] Preferably, in step S1.2, the polycondensation reaction time is 2 hours; in step S1.3, the partial capping reaction time is 30 minutes; in step S1.4, the salt-forming reaction time is 30 minutes.

[0018] Preferably, in steps S1.5 and S1.7, the stirring speed for high-speed dispersion treatment is 1000 - 15000 r / min;

[0019] Preferably, in step S1.7, in the filtration operation, a 200-mesh filter screen is used;

[0020] The purpose of the dehydration operation under vacuum conditions is as follows: During the synthesis of polyurethane, the presence of water can lead to side reactions. Especially when reacting with isocyanates, water reacts with isocyanates to form carbon dioxide and amino compounds, affecting the structure and properties of the final product. Through dehydration treatment, this unwanted side reaction can be avoided.

[0021] Hydrophilic chain extenders, DMPA (bis(2-hydroxyethyl)aminoacetic acid) or DMBA (bis(2-hydroxyethyl)aminobutyric acid), play two key roles in the synthesis of waterborne polyurethane: Improving water solubility and hydrophilicity: Hydrophilic chain extenders can introduce hydrophilic groups into the polyurethane molecule, thereby improving the water solubility and hydrophilicity of polyurethane. This is very important for the stability of the subsequent emulsion because waterborne polyurethane emulsions need to have good water dispersibility and stability. Enhancing dispersibility and stability: In an aqueous system, hydrophilic chain extenders can effectively enhance the water dispersibility of polymers, promoting the dispersion and stability of adhesives. It helps to form a more uniform and delicate dispersion system during the reaction process, avoiding the aggregation or precipitation of polyurethane prepolymers in water.

[0022] Improving the properties of the final product: The introduction of hydrophilic groups not only enhances the compatibility of polyurethane with aqueous media but also has a positive impact on aspects such as the adhesion, flexibility, and mechanical properties of the final waterborne adhesive.

[0023] Functions of antioxidants: Antioxidant 1010 is mainly used to prevent the degradation or invalidation of raw materials and substances generated during the polymerization reaction due to oxidation. The functions of antioxidants in the preparation of waterborne polyurethane-acrylate adhesives are mainly reflected in the following aspects: Preventing oxidation reactions: During the synthesis of polyurethane and acrylate, especially during high-temperature reactions, oxidation reactions may occur due to the presence of oxygen, leading to the degradation of molecular chains and the deterioration of polymer properties. Antioxidants ensure that the molecular chains of the polymer are not excessively degraded by inhibiting oxidation reactions, thus guaranteeing the performance of the final product. Improving thermal stability: Antioxidant 1010 has strong thermal stability and can protect the polymers in the reaction system from oxidation in high-temperature environments, avoiding the degradation of reaction intermediates or polymers caused by oxidation. Improving weather resistance: The addition of antioxidants also helps to improve the long-term stability of the adhesive during use, especially when exposed to air, increasing the weather resistance and service life of the product.

[0024] The addition of hydrophilic chain extenders is mainly to improve the hydrophilicity and water dispersibility of waterborne polyurethane, enhance the stability of the adhesive and the performance of the final product. The addition of antioxidants is to prevent oxidation reactions, protect the polymers in the reaction from oxidative degradation, and ensure the thermal stability and weather resistance of the product.

[0025] Definition of the capping reaction: The capping reaction refers to a chemical reaction in which a capping group is added to terminate or partially terminate the reactivity of the polymer chain. In the synthesis of polyurethane, a compound with reactive groups is added to react with the unreacted isocyanate groups (-NCO), thereby completing the capping process. Capping can limit the chain growth of the polymer, prevent over-polymerization, and also regulate the molecular weight and properties of the final polymer. Why is it called partial capping: This reaction is called partial capping because it does not completely block all isocyanate groups, but only partially caps the end groups of the polyurethane chain. Specifically: In this step, a hydroxyacrylate monomer (such as HEA or HPA monomer) reacts with the isocyanate group (-NCO) to form a hydroxy-capped polyurethane. This partial capping means that not all isocyanate groups react with the hydroxyacrylate monomer, but some isocyanate groups remain unreacted, providing possible active sites for subsequent reactions. This strategy of partial capping is usually to ensure that certain parts of the polyurethane chain have sufficient reactivity to undergo further copolymerization or crosslinking reactions with other subsequent monomers (such as acrylate monomers). Introduction of acrylate functional groups: Introducing acrylate groups onto the polyurethane chain (through the reaction of hydroxyacrylate monomers) is to make the final aqueous polyurethane-acrylate adhesive crosslinkable and have better adhesive properties. Acrylate groups are highly reactive groups and can participate in crosslinking during subsequent polymerization reactions to form a more stable and strong bond. Adjusting molecular weight and properties: By partial capping, the length of the final polyurethane molecular chain can be controlled, and its relative molecular weight can also be adjusted. Appropriate capping can control the solubility, mechanical properties, and other physical and chemical properties of the polyurethane. Avoiding excessive crosslinking or polymerization: If complete capping occurs in this step, it will lead to too high a degree of crosslinking of the polyurethane chain, thus affecting the fluidity, stability, and adhesiveness of the final emulsion. Therefore, partial capping can effectively avoid over-polymerization while retaining an appropriate number of active sites. Enhancing subsequent emulsion synthesis: The partially capped aqueous polyurethane can react better with acrylate monomers and participate in subsequent emulsion polymerization reactions (the polymerization reaction in step S2), thereby forming an aqueous polyurethane-acrylate adhesive with good adhesive properties. In this process, the final properties of the polyurethane-acrylate emulsion, such as adhesive strength, thermal stability, flexibility, etc., all depend on the degree of this capping process and the control of subsequent reactions. Summary: The partial capping reaction is a process of introducing a capping group through the reaction of a hydroxyacrylate monomer with an isocyanate group during the synthesis of aqueous polyurethane. Its purposes are: 1) to control the length and properties of the molecular chain; 2) to retain a certain degree of reactivity in subsequent polymerization reactions to ensure that the final product has good adhesive properties and crosslinkability. This is a very important step that directly affects the performance of the final aqueous adhesive.

[0026] In step S1.5, the purpose of performing high-speed dispersion treatment in the cold water bath device is as follows: To improve the dispersion effect: When the aqueous polyurethane prepolymer is mixed with deionized water, the viscosity of the system is relatively high. Through high-speed dispersion treatment, the polymer can be dispersed into fine particles, improving the uniformity and stability of the system. The cold water bath device can help rapidly cool the reaction mixture, preventing the dispersion effect from decreasing due to excessive temperature, thereby achieving better dispersion and uniformity. To improve the dispersion effect. High-speed dispersion is not only for uniformly mixing each component but also affects the size distribution of the final polymer particles. In the cold water bath device, the temperature of the cooling water is maintained at 5 - 15°C. This low-temperature environment helps control the growth and aggregation of particles, preventing particle aggregation or caking caused by excessive temperature. The cold water bath can effectively control the final size and dispersibility of the particles, which is very important for the performance of the aqueous polyurethane adhesive, especially the fluidity and adhesion of the adhesive.

[0027] The aqueous solution of the post-chain extender is slowly added mainly to avoid excessive heat accumulation caused by rapid reaction during the reaction process. Too fast a reaction may lead to problems such as uneven degree of polymerization and unsatisfactory molecular weight distribution. Slowly adding the aqueous solution of the post-chain extender helps ensure that the reactants react gradually and fully, enabling the chain extension process to proceed uniformly and ultimately obtaining the desired product performance.

[0028] The reason for controlling the addition amount of deionized water is to ensure the formation of an aqueous system. The preparation of the aqueous polyurethane adhesive relies on water as a solvent and dispersion medium. During the synthesis of the aqueous polyurethane prepolymer, a certain amount of water needs to be added to help dissolve and disperse the polyurethane components and promote the aqueous nature of the system. A relatively large amount of deionized water is added mainly to ensure that the reaction system can be effectively dispersed and emulsified, thereby forming a uniform aqueous dispersion system. Too little water makes the reaction system too thick to form a stable emulsion, affecting the performance of the final aqueous adhesive. Setting the amount of deionized water to be 2 - 2.4 times the sum of the other components is to provide an appropriate solvent environment throughout the reaction process, ensuring the smooth progress of the reaction, the uniformity of the system, the control of the reaction rate, and the quality stability of the final product.

[0029] The practice of adding the acrylate monomer mixture in two portions is mainly to control the rate of the polymerization reaction, improve the reaction efficiency, and optimize the final properties of the adhesive. The following are the principles and purposes of adding the acrylate monomer mixture in portions: 1. Control the polymerization reaction rate: Acrylate monomers (such as ethyl acrylate, isooctyl acrylate, etc.) undergo a copolymerization reaction with the aqueous polyurethane prepolymer during the polymerization process to form an aqueous polyurethane-acrylate adhesive. Since the concentration of acrylate monomers is relatively high in the initial stage of the reaction, if all acrylate monomers are added at once, the rate of the polymerization reaction will be too fast, leading to the following problems: Too fast reaction may cause premature crosslinking of polymer molecular chains, forming an uneven polymer structure, which affects the final properties of the adhesive (such as bonding strength, flexibility, etc.). Too fast reaction results in a sharp increase in the viscosity of the polymer, affecting the fluidity of the reaction system, making the reaction incomplete or difficult to control. Therefore, adding acrylate monomers in two portions can: Slowly initiate the polymerization reaction and avoid overly fast polymerization in the initial stage of the reaction. Reduce the initial viscosity of the system, ensure that the system can react uniformly, and avoid local supersaturation or too high viscosity. 2. Promote the formation of a stable copolymer: When the acrylate monomers are added for the first time, the concentration of acrylate is relatively low, which helps to control the interaction between the aqueous polyurethane prepolymer and the acrylate monomers, ensuring that the two can be uniformly mixed and form a stable copolymer. At the beginning of the reaction, the acrylate monomers with low concentration will not overly participate in the crosslinking reaction, which helps to avoid sudden changes in the properties of the adhesive. The second addition of acrylate monomers (adding the remaining 2 / 3 by weight) is to promote the continuous progress of the polymerization reaction and ensure that the polymerization reaction can be completed under appropriate conditions to form a stable copolymer. Reach the required acrylate content to ensure that the adhesive has appropriate mechanical properties (such as water resistance, bonding strength, etc.). 3. Avoid local over-polymerization and non-uniformity: If all acrylate monomers are added at once, local over-polymerization or crosslinking may occur in some areas of the reaction system, resulting in non-uniform properties of the adhesive. Adding acrylate monomers in batches can avoid this situation and ensure the uniformity and consistency of the entire system by controlling the progress of the reaction. 4. Improve the activity of the chain initiator: In the polymerization reaction, the chain initiator (azobisisobutyronitrile) initiates the activity of the polymerization reaction, and it can usually be better activated and carry out the polymerization reaction when the concentration of acrylate monomers is relatively low. By adding acrylate monomers in portions, sufficient monomers can be provided to the chain initiator at an appropriate time point, ensuring the maximization of the role of the initiator and promoting the smooth progress of the polymerization process. Therefore, the main purpose of adding the acrylate monomer mixture separately is to control the rate of the polymerization reaction, optimize the reaction conditions, avoid the adverse effects caused by too fast reaction, and ensure the stability and uniformity of the final properties of the adhesive. By this method of adding in portions, the structure and properties of the adhesive can be effectively controlled, improving its performance in practical applications.

[0030] Acetone is used as a viscosity regulator in this preparation method. Its main function is to reduce the viscosity of the reaction system, making the reaction mixture easier to handle and disperse. However, acetone is not expected to remain in the product for a long time because it will affect the performance, stability, and safety of the final product. Specifically, the addition amount of acetone is 10%-30% of the amount of the mixture after the partial capping reaction, preferably 15%-17%.

[0031] After the preparation of the waterborne polyurethane-acrylate adhesive, during its use, a waterborne curing agent is selected. The specific model of the waterborne curing agent is DB-601 waterborne curing agent, which is from Zhejiang Duobang New Materials Co., Ltd. The usage amount of the waterborne curing agent is 1%-3% of the weight of the waterborne polyurethane-acrylate adhesive.

[0032] The principle of the present invention is as follows: A polyurethane prepolymer is synthesized through an aliphatic polycarbonate-polyether polyol, a hydrophilic chain extender, and an isocyanate, and then it is partially capped with a hydroxyacrylate monomer. After

[0033] neutralization with a neutralizing agent, low-temperature chain extension with a post-chain extender, and seed emulsion polymerization, a core-shell structured waterborne polyurethane-acrylate emulsion is formed. By selecting the types of polyurethane-acrylate monomers and optimizing the ratio of the chain segments, the synthesized composite adhesive has pressure sensitivity and provides initial strength. During the later use process, through the crosslinking of the curing agent, the bonding strength and wash resistance of the composite fabric are improved.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] First, through the treatment of the aliphatic polycarbonate-polyether polyol and other auxiliary materials, the polycondensation reaction of the isocyanate is completed under temperature control conditions, and it is combined with the hydroxyacrylate monomer through a partial capping reaction to form a waterborne polyurethane prepolymer. In this process, through steps such as cooling, viscosity adjustment, and addition of a post-chain extender, the molecular structure of the polymer is precisely controlled, making the final product have good physical and chemical properties. Second, a waterborne polyurethane-acrylate adhesive emulsion is formed by mixing the waterborne polyurethane prepolymer with acrylate monomers, a chain initiator, and deionized water and then carrying out a polymerization reaction. During the polymerization process, the remaining acrylate monomers are gradually added to ensure the adhesion performance of the adhesive and the stability of the emulsion. Finally, after the polymerization reaction is completed, by adding auxiliaries such as defoamers and leveling agents, the surface performance of the adhesive is further optimized to ensure its good coatability, leveling property, and defoaming property, and to improve the application effect of the final adhesive.

[0036] In summary, through the semi - continuous seed emulsion polymerization method, the present invention copolymerizes acrylate monomers onto the polyurethane main chain to form an emulsion with a core - shell structure. This structure of the emulsion exhibits good stability and hydrolysis resistance; by selecting the types of polyurethane - acrylate monomers and optimizing the ratio of the chain segments, the synthesized adhesive not only has pressure - sensitivity and good initial adhesion strength, but also can further improve the adhesion and hydrolysis resistance through the cross - linking reaction with the curing agent during subsequent use. Among them, the soft monomer acrylate with a lower glass transition temperature provides the initial pressure - sensitivity, and at the same time, hydroxy - acrylate monomers are added to participate in the free - radical polymerization reaction, and the hydroxyl groups are grafted to the amino groups at the ends of the polyurethane, increasing the stability of the core - shell structure. Detailed implementation mode

[0037] The following are specific examples of the present invention to further describe the technical solutions of the present invention, but the present invention is not limited to these examples.

[0038] A preparation method of an aqueous polyurethane - acrylate adhesive for fabric lamination, the preparation method of the aqueous polyurethane - acrylate adhesive comprising the following steps:

[0039] S1 Preparation of an aqueous polyurethane prepolymer: S1.1 Vacuum dehydration pretreatment: After uniformly mixing an aliphatic polycarbonate - polyether polyol, a non - ionic polyol, a hydrophilic chain extender, and antioxidant 1010, vacuum dehydration operation is carried out at 120 °C. After the dehydration operation is completed, a dehydrated mixture is obtained; S1.2 Isocyanate polycondensation reaction: The temperature of the dehydrated mixture is reduced to 55 °C, isocyanate is added to the dehydrated mixture, and after mixing evenly, the reaction is carried out at a temperature of 110 °C to obtain a mixture after the isocyanate polycondensation reaction; S1.3 Partial capping reaction: The temperature of the mixture after the isocyanate polycondensation reaction is cooled to 80 °C, hydroxy - acrylate monomers are added to the mixture after the isocyanate polycondensation reaction, and after mixing evenly, the reaction is carried out at a temperature of 80 °C. After the reaction is completed, a mixture after the partial capping reaction is obtained; S1.4 Salt formation: The temperature of the mixture after the partial capping reaction is reduced to 55 °C, a neutralizing agent and a viscosity - regulating agent are added to the mixture after the partial capping reaction, and after mixing evenly, a salt - formation reaction is carried out at a temperature of 55 °C. After the reaction is completed, a mixture after the salt - formation reaction is obtained; S1.5 High - speed dispersion: After the temperature of the mixture after the salt - formation reaction is reduced to 25 °C, the mixture after the salt - formation reaction is placed in a cold - water bath device, then deionized water is added, and then high - speed dispersion treatment is carried out to obtain an initial dispersion mixture; the temperature of the cold water in the cold - water bath device is 5 °C; S1.6 Dropwise addition of the post - chain extender: An aqueous solution of the post - chain extender is dropwise added to the initial dispersion mixture, the dropwise addition time is T1, and after the dropwise addition is completed, an initial target mixture is obtained; S1.7 Post - treatment: The initial target mixture is subjected to high - speed dispersion treatment. After the dispersion is completed, filtration operation and removal of the viscosity - regulating agent operation are carried out in sequence to obtain an aqueous polyurethane prepolymer;

[0040] The aliphatic polycarbonate-polyether polyol is specifically PPCD, the non-ionic polyol is specifically N120; the hydrophilic chain extender is DMPA, the isocyanate is specifically IPDI; the neutralizing agent is triethylamine; the post-chain extender aqueous solution is an ethylenediamine aqueous solution with a concentration of 50%; the hydroxyacrylate monomer is specifically the HEA monomer; the viscosity regulator is selected as acetone;

[0041] By weight ratio, aliphatic polycarbonate-polyether polyol: non-ionic polyol: hydrophilic chain extender: isocyanate: antioxidant 1010: hydroxyacrylate monomer: neutralizing agent: post-chain extender is 65-80:1-5:2-5:20-30:0.1-0.5:2-5:1-3:1-3;

[0042] In step S1, the amount of deionized water used is 2-2.4 times the sum of the weights of the aliphatic polycarbonate-polyether polyol, non-ionic polyol, hydrophilic chain extender, isocyanate, antioxidant 1010, hydroxyacrylate monomer, neutralizing agent and post-chain extender;

[0043] S2 Synthesis of waterborne polyurethane-acrylate emulsion: S2.1 Polymerization reaction: Add the waterborne polyurethane prepolymer, 1 / 3 weight of the acrylate monomer mixture, the chain initiator and deionized water into a constant temperature reaction device. After mixing evenly, start the constant temperature reaction device and set the working temperature of the constant temperature reaction device to 85°C; after the reaction time T2, add 2 / 3 weight of the acrylate monomer mixture in a dropping manner, and the dropping time is T3; after the dropping is completed, continue to keep the temperature for reaction, and the reaction time is T4. After the reaction is completed, obtain the polymerization reactant. S2.2 Cooling and additive addition: Cool the temperature of the mixture after the polymerization reaction to 36°C, add the defoaming agent and the leveling agent, and carry out stirring operation. After stirring evenly, obtain the waterborne polyurethane-acrylate adhesive;

[0044] The acrylate monomer mixture includes ethyl acrylate, isooctyl acrylate, n-butyl acrylate and hydroxyacrylate, and the chain initiator is azobisisobutyronitrile; the leveling agent is specifically the Tego410 type leveling agent; the defoaming agent is specifically the BYK-024 type defoaming agent.

[0045] By weight ratio, waterborne polyurethane prepolymer: ethyl acrylate: isooctyl acrylate: n-butyl acrylate: hydroxyacrylate: chain initiator: defoaming agent: leveling agent: deionized water is 100:10-15:1-3:3-6:1-3:0.05-1:0.05-1:0.05-1:35-50.

[0046] In step S1.1, the water content in the dehydrated mixture is less than 300 ppm.

[0047] In step S1.2, the polycondensation reaction time of the isocyanate is 2 hours; the time for the partial capping reaction is 30 minutes; the time for the salt formation reaction is 30 minutes, T1 is 50 minutes; T2 is 60 minutes; T3 is 30 minutes, and T4 is 120 minutes. These times are generous enough to ensure the completion of the reaction.

[0048] In steps S1.5 and S1.7, the stirring speed for the high-speed dispersion treatment is 1000 - 15000 r / min;

[0049] In step S1.7, in the filtration operation, a 200-mesh filter screen is used;

[0050] In the operation of removing the viscosity regulator, acetone is removed by vacuum distillation.

[0051] Waterborne polyurethane-acrylate adhesive products 1, 2 and the comparative product are prepared respectively according to the above methods. After the preparation is completed, during the use process, a waterborne curing agent is selected. The specific model of the waterborne curing agent is DB-601 waterborne curing agent, which is from Zhejiang Duobang New Materials Co., Ltd. The usage amount of the waterborne curing agent is 2% of the product weight. The weight parameters and product performance test parameters in the specific preparation process are shown in Table 1:

[0052] Table 1

[0053] Test standard for viscosity: Refer to the rotational viscosity test method of ASTM D1084-16(2021).

[0054] Test standard for solid content: Refer to the test method for non-volatile matter in the test method for synthetic resin emulsions of GB / T11175-2021.

[0055] Test method for emulsion stability: Centrifuge at 3000 r / min for 15 min in a centrifuge, and observe whether precipitation and emulsion stratification occur.

[0056] Test method for water absorption: Refer to the test method for water absorption of plastics of GB / T1034-2008.

[0057] Test standards for tensile strength and elongation at break: Refer to GB / T 528-2009 for testing.

[0058] Test standard for initial tack in a loop: Refer to the test method for initial tack of adhesive tapes - loop method of GB / T31125-2014.

[0059] Test standard for peel strength: The peel strength of flexible materials to flexible materials in the test standard of GB / T 2791-1995.

[0060] Test standard for washing conditions: Refer to the washing test method in HG / T 3697-2016.

[0061] The performance analysis is as follows:

[0062] Viscosity: Viscosity is an important indicator for evaluating the fluidity and workability of adhesives. The viscosities of Product 1 and Product 2 are 200 mPa·s and 160 mPa·s respectively, which are much higher than 80 mPa·s of the comparative product. The higher viscosity helps to provide better control during coating and bonding processes, thus reducing dripping and uneven coating situations.

[0063] Emulsion stability: Both Product 1 and Product 2 show good emulsion stability without precipitation or delamination. This is a particularly important property for aqueous systems because any precipitation or delamination may lead to inconsistencies during construction and affect the quality of the final product.

[0064] Water absorption rate: The water absorption rate of aqueous polyurethane is an indicator for evaluating its waterproof performance. The water absorption rates of Product 1 and Product 2 are 4.5% and 6.0% respectively, which are significantly better than 12.6% of the comparative product. This indicates that the modified aqueous polyurethane adhesive has better resistance to water intrusion.

[0065] Tensile strength and elongation at break: The tensile strengths of Product 1 and Product 2 are 32 MPa and 29 MPa respectively, and the elongations at break are 800% and 880% respectively, showing excellent flexibility and tensile properties.

[0066] Initial tack and peel strength: Initial tack and peel strength are important indicators for evaluating the immediate and long-term bonding ability of adhesives. Product 1 and Product 2 show good initial tack and peel strength, especially without warping or delaminating after washing, indicating their good wash resistance.

[0067] From the performance comparison, it can be seen that the comparative product without acrylate modification has a higher water absorption rate and relatively poor initial tack, especially it is not wash-resistant, while the modified aqueous polyurethane-acrylate adhesive products 1 and 2 have better comprehensive performance.

[0068] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains may make various modifications or supplements to the described specific embodiments or use similar means for substitution, but will not deviate from the spirit of the present invention or exceed the defined scope. Although the present invention has been described in detail in the foregoing description, such description is considered to be illustrative or exemplary rather than restrictive. It should be understood that within the scope of the following claims, changes and modifications can be made by those of ordinary skill in the art. Specifically, the present invention encompasses additional embodiments having any combination of features from the different embodiments described above. With respect to the use of the expressions "generally" or "substantially", this patent application should be understood to disclose that the same fully meets these features and values, i.e., without the foregoing being characterized as "generally" or "substantially".

Claims

1. A preparation method of an aqueous polyurethane-acrylate adhesive for fabric lamination, characterized in that, The preparation method of the waterborne polyurethane-acrylate adhesive comprises the following steps: S1 Preparation of waterborne polyurethane prepolymer: S1.1 Dehydration pretreatment: After uniformly mixing an aliphatic polycarbonate-polyether polyol PPCD, a nonionic polyol N120, a hydrophilic chain extender, and an antioxidant, carry out dehydration operation to obtain a dehydrated mixture; S1.2 Isocyanate polycondensation reaction: After cooling the dehydrated mixture, add an isocyanate to the dehydrated mixture for polycondensation reaction to obtain a mixture after the isocyanate polycondensation reaction; S1.3 Partial capping reaction: After cooling the mixture after the isocyanate polycondensation reaction, add a hydroxyacrylate monomer to the mixture after the isocyanate polycondensation reaction for partial capping reaction to obtain a mixture after the partial capping reaction; S1.4 Salt formation: After cooling the mixture after the partial capping reaction, add a neutralizing agent and a viscosity regulator to the mixture after the partial capping reaction for salt formation reaction to obtain a mixture after the salt formation reaction; S1.5 High-speed dispersion: After cooling the mixture after the salt formation reaction, place it in a cold water bath device, then add deionized water, and then carry out high-speed dispersion treatment to obtain an initial dispersed mixture; S1.6 Dropwise addition of post-chain extender: Dropwise add an aqueous solution of the post-chain extender to the initial dispersed mixture for reaction to obtain an initial target mixture; S1.7 Post-treatment: Carry out high-speed dispersion treatment on the initial target mixture. After the dispersion is completed, successively carry out filtration operation and removal of the viscosity regulator operation to obtain the waterborne polyurethane prepolymer; S2 Synthesis of waterborne polyurethane-acrylate emulsion: S2.1 Polymerization reaction: After uniformly mixing the waterborne polyurethane prepolymer, a partial acrylate monomer mixture, a chain initiator, and deionized water, carry out polymerization reaction; After the reaction is completed, add the remaining acrylate monomer mixture in a dropwise manner and continue the polymerization reaction to obtain a polymerization reaction mixture; S2.2 Additives addition: After cooling the mixture after the polymerization reaction, add an antifoaming agent and a leveling agent, and stir until uniform to obtain the waterborne polyurethane-acrylate adhesive; The hydrophilic chain extender is DMPA or DMBA; the acrylate monomer mixture includes ethyl acrylate, isooctyl acrylate, n-butyl acrylate and hydroxyacrylate; the chain initiator is azobisisobutyronitrile; the antioxidant is antioxidant 1010; the viscosity regulator is acetone; in step S1, by weight, aliphatic polycarbonate-polyether polyol PPCD: non-ionic polyol N120: hydrophilic chain extender: isocyanate: antioxidant 1010: hydroxyacrylate monomer: neutralizer: post-chain extender is 65-80:1-5:2-5:20-30:0.1-0.5:2-5:1-3:1-3; the amount of deionized water used is 2-2.4 times the sum of the weights of aliphatic polycarbonate-polyether polyol PPCD, non-ionic polyol N120, hydrophilic chain extender, isocyanate, antioxidant 1010, hydroxyacrylate monomer, neutralizer and post-chain extender; in step S2.1, by weight, waterborne polyurethane prepolymer: ethyl acrylate: isooctyl acrylate: n-butyl acrylate: hydroxyacrylate: chain initiator: deionized water is 100:10-15:1-3:3-6:1-3:0.05-1:35-50.

2. The preparation method of the waterborne polyurethane-acrylate adhesive for fabric lamination according to claim 1, characterized in that, In the operation of removing the viscosity regulator, acetone is removed by means of vacuum distillation.

3. The preparation method of the waterborne polyurethane-acrylate adhesive for fabric lamination according to claim 1, characterized in that, In the aqueous solution of the post-chain extender, the concentration of ethylenediamine is 50%.

4. The preparation method of the waterborne polyurethane-acrylate adhesive for fabric lamination according to claim 1, wherein, In step S2.1, by weight, part of the acrylate monomer mixture: the remaining acrylate monomer mixture is 1:

2.

5. The preparation method of the waterborne polyurethane-acrylate adhesive for fabric lamination according to claim 1, characterized in that, In step S1.1, the dehydration operation is carried out under vacuum conditions, the temperature of the dehydration operation is 110-120 °C, and the water content in the dehydration mixture is less than 300 ppm.

6. The preparation method of the aqueous polyurethane-acrylate adhesive for fabric lamination according to claim 1, wherein, In step S1.2, the target temperature of the cooling operation is below 60 °C, and the polycondensation reaction temperature is 100-110 °C; in step S1.3, the target temperature of the cooling operation is 80 °C, and the partial capping reaction temperature is 80 °C; in step S1.4, the target temperature of the cooling operation is 55-60 °C, and the salt-forming reaction temperature is 55-60 °C; in step S1.5, the target temperature of the cooling operation is not higher than 30 °C, and the temperature of the cold water in the cold water bath device is 5-15 °C; in step S2.1, the polymerization reaction temperature is 80-85 °C; in step S2.2, the target temperature of the cooling operation is below 40 °C.

7. The preparation method of the waterborne polyurethane-acrylate adhesive for fabric lamination according to claim 1, wherein In step S2.2, the leveling agent is specifically one of Tego410 type leveling agent, Tego425 type leveling agent and Runhe T1008 type leveling agent; the defoaming agent is specifically one of 810S type defoaming agent and BYK-024 type defoaming agent.

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