Preparation method and application of vanillin-based chain extender and waterborne polyurethane film-forming agent

Abstract

The invention discloses a preparation method and application of a vanillin-based chain extender and a waterborne polyurethane film-forming agent, and belongs to the technical field of waterborne polyurethane preparation.The preparation method comprises the steps that firstly, vanillin and 4, 4-diaminodiphenylmethane are subjected to a Schiff base reaction to synthesize the vanillin-based chain extender, then the vanillin-based chain extender reacts with isocyanic acid and polyhydric alcohols to generate a prepolymer, and then the prepolymer is subjected to a reaction with the waterborne polyurethane film-forming agent to obtain the vanillin-based chain extender. Then synthesizing a waterborne polyurethane emulsion through an emulsification reaction, adding an amine chain extender after emulsification, and carrying out a post-chain extension reaction, so as to obtain the waterborne polyurethane film-forming agent. The waterborne polyurethane film-forming agent prepared by the invention can be used for preparing a glass fiber wire-drawing impregnating compound, a fabric sizing agent or a coating and the like, the film-forming agent is environment-friendly, the production process is green and pollution-free, an organic solvent does not need to be added in the reaction process, and zero VOC (Volatile Organic Compounds) emission can be realized; meanwhile, the special structure of the vanillin-based chain extender also endows the waterborne polyurethane film-forming agent with higher rigidity.

Description

Technical Field

[0001] The invention belongs to the technical field of waterborne polyurethane preparation, and specifically relates to a preparation method and application of a vanillin-based chain extender and a waterborne polyurethane film-forming agent. Background Art

[0002] Glass fiber sizing plays a role in protecting, lubricating, bundling and strengthening the glass fiber during the preparation process. It is composed of coupling agent, film former, lubricant and antistatic agent. Film former is also called binder or bundling agent. It is the main component of glass fiber sizing besides water. Its content accounts for about 2%~10% of the total sizing. Although its content is low, as the main component of glass fiber sizing, it plays an important role in improving the interface strength of glass fiber surface, enhancing the mechanical strength and corrosion resistance of glass fiber and composite materials.

[0003] Waterborne polyurethane used in glass fiber manufacturing is referred to as waterborne polyurethane film-forming agent. The emission of volatile organic compounds in the manufacturing and use process of waterborne polyurethane is almost zero, and it is an environmentally friendly polymer material. Waterborne polyurethane has the characteristics of adjustable hardness, wear resistance, solvent resistance and strong adhesion with most materials, and has developed rapidly in recent years. As a film-forming agent in the wetting agent, waterborne polyurethane emulsion is a polymer material with repeated urethane units in its molecular structure. It is mainly prepared by polyurethane prepolymer and chain extender, and has a microphase separation structure, including soft segment and hard segment. The soft segment is composed of polyols, which provides the elasticity of the material, while the hard segment is composed of diisocyanates and small molecule diols or diamines (chain extenders), which provide physical or chemical cross-linking points and enhance its mechanical strength. Therefore, the mechanical properties of materials obtained by different diol chain extenders and different molecular structures are also different. The main raw materials of polyurethane usually come from the petroleum industry, but petroleum-based materials have the disadvantages of being non-renewable and difficult to biodegrade, causing serious environmental problems.

[0004] Therefore, it is of far-reaching significance to develop a vanillin-based chain extender and water-based polyurethane film-forming agent based on renewable and degradable biomass raw materials. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a vanillin-based chain extender and a preparation method and application of an aqueous polyurethane film-forming agent, so as to solve the technical problems of poor environmental protection and mechanical properties of the aqueous polyurethane film-forming agent in the existing glass fiber impregnating agent.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a vanillin-based chain extender, the chemical structural formula of which is: .

[0007] The present invention also discloses a method for preparing the vanillin-based chain extender, comprising: reacting vanillin, 4,4-diaminodiphenylmethane and methanol in N 2 The mixture is mixed and reacted under an atmosphere. After the reaction is completed, the mixture is filtered under reduced pressure, washed and dried to obtain a vanillin-based chain extender.

[0008] Preferably, the usage ratio of vanillin, 4,4-diaminodiphenylmethane and methanol is (0.08-0.8) mol: (0.04-0.4) mol: (50-300) mL.

[0009] Preferably, the reaction temperature is 55-65°C under N 2 The reaction was refluxed under atmosphere for 6-10 h; the washing condition was methanol washing; the drying condition was vacuum drying at 60-80 °C for 8-12 h.

[0010] The invention also discloses a method for preparing an aqueous polyurethane film-forming agent, which adopts the vanillin-based chain extender prepared by the preparation method as a reaction raw material for preparation, comprising: mixing polyester polyol and polyether polyol, performing dehydration treatment, adding diisocyanate and an organic tin catalyst under the protection of an inert gas to perform a prepolymerization reaction to obtain a polyurethane prepolymer; then adding the vanillin-based chain extender to perform a prepolymerization reaction to obtain a polyurethane resin; then adding a first portion of deionized water during stirring to perform an emulsification reaction, and obtaining an aqueous polyurethane emulsion after the emulsification is completed; adding an amine chain extender to perform a post-chain extension reaction, adding a second portion of deionized water again, and stirring to obtain the aqueous polyurethane film-forming agent.

[0011] Preferably, the molar ratio of polyester polyol to polyether polyol is 1:1; The polyester polyol is one or two of polycarbonate, poly(hexanediol adipate) and poly(neopentyl adipate); the average molecular weight of the polycarbonate is 2000 g / mol, the average molecular weight of the poly(hexanediol adipate) is 2000 g / mol, and the average molecular weight of the poly(neopentyl adipate) is 2000 g / mol; The polyether polyol is at least one of polyethylene glycol monomethyl ether and polytetramethylene furan polyether diol; the average molecular weight of polyethylene glycol monomethyl ether is 1000 g / mol, and the average molecular weight of polytetramethylene furan polyether diol is 1000 g / mol; The vacuum degree of dehydration is -0.01~-0.1MPa, the temperature of dehydration is 110~130℃, and the time of dehydration is 1~3h.

[0012] Preferably, the diisocyanate is at least one of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, 2,6-hexamethylene diisocyanate and isophorone diisocyanate; The organotin catalyst is at least one of dibutyltin dilaurate, stannous octoate, dibutyltin didodecylsulfide and dibutyltin diacetate; The mass fraction of diisocyanate is 10%~30%; The mass fraction of the organotin catalyst is 0.02%; The prepolymerization temperature is 80~100℃ and the time is 2~4h; The mass fraction of vanillin-based chain extender is 1%~9%; The prepolymerization reaction temperature is 80~100°C and the time is 1~2h.

[0013] Preferably, the amine chain extender is any one of isophoronediamine and ethylenediamine; The mass fraction of amine chain extenders is 1.10%~7.05%; The temperature of the emulsification reaction is 35~45°C, and the stirring rate is 1500~2200rpm; The amount of the first deionized water added is 40% to 50% of the total mass of the polyurethane resin, and the amount of the second deionized water added is 5% to 10% of the total mass of the waterborne polyurethane emulsion.

[0014] The invention also discloses an aqueous polyurethane film-forming agent, which is prepared by adopting the preparation method.

[0015] The invention also discloses the use of the aqueous polyurethane film-forming agent prepared by the preparation method in preparing glass fiber drawing sizing agent, fabric sizing agent, leather finishing agent, carbon fiber sizing agent, adhesive or coating.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a vanillin-based chain extender. The presence of benzene rings in the vanillin-based chain extender increases the rigidity of an aqueous polyurethane film-forming agent attached to the surface of glass fiber, increases the mechanical strength of the glass fiber, and at the same time, the increase in the hard segment content promotes microphase separation, which is helpful for improving mechanical properties. At the same time, by adjusting the hard-soft ratio and the imine content, an aqueous polyurethane film-forming agent that meets different needs of people can be designed. The highly symmetrical structure and C=N double bond contained in the polyurethane are conducive to improving mechanical properties, and the imine bond undergoes a rapid exchange reaction as the temperature increases, which also gives the material self-healing and excellent reprocessing properties.

[0017] The present invention also discloses a method for preparing the vanillin-based chain extender. The presence of benzene rings in the vanillin-based chain extender not only improves the rigidity of the waterborne polyurethane film-forming agent attached to the surface of the glass fiber, but also significantly increases the mechanical strength of the glass fiber. This performance improvement is of great significance for the expansion of glass fiber in high-end application fields. No organic solvent is required during the preparation process, and zero emission of VOC is achieved, which meets the current green and environmentally friendly production requirements.

[0018] The present invention also discloses a method for preparing an aqueous polyurethane film-forming agent, using the vanillin-based chain extender seat raw material prepared by the above preparation method, and adjusting the hard-soft ratio and the imide content to design an aqueous polyurethane film-forming agent that meets different needs, so that the film-forming agent can exert excellent performance in a variety of applications. The highly symmetrical structure and C=N double bond in the polyurethane, as well as the rapid exchange reaction of the imide bond, give the material self-healing and excellent reprocessability, which greatly improves the service life and economic benefits of the material. The entire preparation process is green and pollution-free, meets environmental protection requirements, and helps promote the sustainable development of the polyurethane industry.

[0019] The present invention also discloses an aqueous polyurethane film-forming agent prepared by the above preparation method. The presence of benzene rings improves the rigidity of the aqueous polyurethane film-forming agent attached to the surface of glass fiber and increases the mechanical strength of glass fiber. The increase in the hard segment content promotes microphase separation and helps to improve mechanical properties such as tensile strength, bending strength and impact strength. The presence of dynamic imine bonds gives the material excellent self-healing and reprocessing properties, which means that when the material is damaged, it can self-repair under certain conditions, extending its service life.

[0020] The present invention also discloses the use of the aqueous polyurethane film-forming agent prepared by the above-mentioned preparation method in the preparation of glass fiber drawing sizing, fabric sizing agent, leather finishing agent, carbon fiber sizing agent, adhesive or coating; the film-forming agent is relatively friendly to the environment, the production process is green and pollution-free, no organic solvent needs to be added during the reaction, and 0 VOC emissions can be achieved. At the same time, the special structure of the vanillin-based chain extender also gives the aqueous polyurethane film-forming agent stronger rigidity, and an aqueous polyurethane film-forming agent that meets people's different needs can be designed by adjusting the soft-hard ratio and the imide content. The glass fiber produced by the film-forming agent can be used to enhance the functional requirements of polyimide, polyetheretherketone, polysulfone, etc. for aviation, aerospace, automobiles and other fields for light weight and high strength. The presence of the dynamic imide bond of the film-forming agent also gives the material excellent self-healing and reprocessing performance, increases the service life of the material, so the aqueous polyurethane film-forming agent has significant economic benefits. The impregnating agent prepared by using the film-forming agent provided by the present invention as the main film-forming agent is applied to FRP products, and the impregnation speed is fast, and the tensile strength, flexural strength, flexural modulus and unnotched impact strength are significantly improved compared with the comparative impregnating agent A. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the infrared spectrum of the vanillin-based chain extender prepared in Example 1 of the present invention; Figure 2 The vanillin-based chain extender prepared in Example 1 of the present invention 1 H NMR spectrum; Figure 3 This is a tensile stress-strain curve of the waterborne polyurethane film-forming agent in Example 2 of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings: The present invention uses vanillin as a bio-based raw material to prepare a vanillin-based chain extender, and adopts the vanillin-based chain extender to prepare an aqueous polyurethane film-forming agent. The aqueous polyurethane film-forming agent is applied to the preparation of glass fiber products, and the comprehensive performance indicators of the prepared products all meet or exceed the requirements of the target application field of the material. First, vanillin and 4,4-diaminodiphenylmethane are reacted by Schiff base to synthesize the vanillin-based chain extender, and then the vanillin-based chain extender is reacted with isocyanic acid and polyol to generate a prepolymer, and then an aqueous polyurethane emulsion is synthesized by emulsification reaction, and an amine chain extender is added after emulsification to perform a post-chain extension reaction to obtain an aqueous polyurethane film-forming agent. The aqueous polyurethane film-forming agent prepared by the present invention can be used to prepare glass fiber drawing sizing, fabric sizing agent or coating, etc. The film-forming agent is relatively friendly to the environment, the production process is green and pollution-free, no organic solvent needs to be added during the reaction, and 0 VOC emissions can be achieved. At the same time, the special structure of the vanillin-based chain extender also gives the aqueous polyurethane film-forming agent stronger rigidity.

[0025] The present invention discloses a vanillin-based chain extender, which is 4,4'-((1E, 1'E)-(methylenebis(4,1-phenylene)bis(azamethylene))bis(methylmethylene)bis(2-methoxyphenol) (VSB), and has the structural formula: .

[0026] The preparation method of the vanillin-based chain extender VSB comprises: mixing vanillin, 4,4-diaminodiphenylmethane and methanol in a designed ratio in N 2 The mixture was added into a four-necked flask under an atmosphere for reaction to synthesize the vanillin-based chain extender VSB.

[0027] Furthermore, the usage ratio of the vanillin, 4,4-diaminodiphenylmethane and methanol is (0.08-0.8) mol: (0.04-0.4) mol: (50-300) mL.

[0028] Furthermore, the reaction temperature is 55-65°C under N 2 Reflux under atmosphere for 6-10 h to obtain a crude product containing VSB.

[0029] Furthermore, the bright yellow solution obtained by the above reaction was filtered under reduced pressure to obtain a yellow precipitate, which was washed three times with methanol, and vacuum dried at 60-80° C. for 8-12 h to obtain the vanillin-based chain extender, 4,4'-((1E,1'E)-(methylenebis(4,1-phenylene)bis(azamethylene))bis(methylmethylene)bis(2-methoxyphenol).

[0030] The present invention uses the above-mentioned vanillin-based chain extender as a component and adopts the acetone method to successfully prepare a waterborne polyurethane film-forming agent. The preparation method of the waterborne polyurethane comprises the following steps: 1) Mix polyester polyol and polyether polyol in a molar ratio of 1:1 and add them into a four-necked flask, dehydrate them at a pressure of -0.01~-0.1MPa, a temperature of 110~130℃, and a dehydration time of 1~3h.

[0031] 2) Under the protection of inert gas, add 10% to 30% of diisocyanate by mass to the dehydrated polyol, and add 0.02% of organic tin catalyst by mass. Carry out prepolymerization at 80 to 100°C for 2 to 4 hours to obtain polyurethane prepolymer.

[0032] 3) Add 1% to 9% by mass of a vanillin-based chain extender to the prepolymer 1 to carry out a prepolymerization reaction to obtain a polyurethane resin.

[0033] 4) Pour the above polyurethane prepolymer 2 into a dispersion kettle and stir. During the stirring process, add the first portion of deionized water for emulsification. After the emulsification is completed, an aqueous polyurethane emulsion is obtained; 1.10% to 7.05% of an amine chain extender is added for post-chain extension, and the second portion of deionized water is added again. After stirring, an aqueous polyurethane film-forming agent is obtained.

[0034] In step 1), the polyester polyol is one or a combination of polycarbonate, poly(hexanediol adipate) and poly(neopentyl adipate). The average molecular weight of polycarbonate is 2000 g / mol, the average molecular weight of poly(hexanediol adipate) is 2000 g / mol, and the average molecular weight of poly(neopentyl adipate) is 2000 g / mol.

[0035] In step 1), the polyether polyol is one or both of polyethylene glycol monomethyl ether and polytetramethylene glycol diol. The average molecular weight of polyethylene glycol monomethyl ether is 1000 g / mol, and the average molecular weight of polytetramethylene glycol diol is 1000 g / mol.

[0036] In step 2), the prepolymerization temperature is 80-100°C, and the diisocyanate reaction time is 2-4 hours.

[0037] In step 2), the diisocyanate is one or more combinations of 2,4-toluene diisocyanate (TDI), 2,6-toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), 2,6-hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI).

[0038] In step 2), the organotin catalyst is a mixture of one or more of dibutyltin dilaurate, stannous octoate, dibutyltin didodecylsulfide, and dibutyltin diacetate. Dibutyltin dilaurate is preferred.

[0039] In step 3), the temperature of the prepolymerization reaction of the vanillin-based chain extender is 80-100° C. and the duration is 1-2 hours.

[0040] In step 4), the amine chain extender is any one of isophoronediamine and ethylenediamine.

[0041] In step 4), the emulsification temperature is 35-45°C and the stirring speed is 1500-2200 rpm.

[0042] In step 4), the amount of the first portion of deionized water added is 40% to 50% of the total mass of the polyurethane resin, and the amount of the second portion of deionized water added is 5% to 10% of the total mass of the aqueous polyurethane emulsion.

[0043] The present invention also discloses an aqueous polyurethane film-forming agent prepared by the above-mentioned preparation method. The presence of benzene rings in the vanillin-based chain extender VSB increases the rigidity of the aqueous polyurethane film-forming agent attached to the surface of the glass fiber, increases the mechanical strength of the glass fiber, and at the same time, the increase in the hard segment content promotes microphase separation, which is helpful for improving the mechanical properties. At the same time, by adjusting the hard-soft ratio and the imide content, an aqueous polyurethane film-forming agent that meets people's different needs can be designed. The highly symmetrical structure and C=N double bond contained in the polyurethane are conducive to improving the mechanical properties, and the imide bond undergoes a rapid exchange reaction as the temperature increases, which also gives the material self-healing and excellent reprocessing properties.

[0044] The present invention also discloses the use of the aqueous polyurethane film-forming agent prepared by the above-mentioned preparation method in the preparation of glass fiber drawing sizing, fabric sizing, leather finishing agent, carbon fiber sizing agent, adhesive or coating. The aqueous polyurethane film-forming agent is used to prepare glass fiber drawing sizing, fabric sizing, leather finishing agent, carbon fiber sizing agent, adhesive or coating, etc. The aqueous polyurethane film-forming agent is relatively friendly to the environment, the production process is green and pollution-free, no organic solvent is required to be added during the reaction process, and 0 VOC emissions can be achieved. At the same time, the special structure of the vanillin-based chain extender also gives the aqueous polyurethane film-forming agent stronger rigidity, and an aqueous polyurethane film-forming agent that meets different needs of people can be designed by adjusting the soft-hard ratio and the imide content. The glass fiber produced by the film-forming agent can be used to enhance the functional requirements of polyimide, polyetheretherketone, polysulfone, etc. for aviation, aerospace, automobile and other fields for light weight and high strength. The presence of the dynamic imide bond of the film-forming agent also gives the material excellent self-healing and reprocessing performance, increasing the service life of the material, so the aqueous polyurethane film-forming agent has significant economic benefits. The waterborne polyurethane emulsion is modified by unsaturated dibasic acid, and the modified polyurethane emulsion film-forming agent is used to prepare the wetting agent, which is then applied to the preparation of FRP products. The presence of benzene rings in the vanillin-based chain extender improves the rigidity of the waterborne polyurethane film-forming agent attached to the surface of the glass fiber and increases the mechanical strength of the glass fiber. At the same time, the increase in the hard segment content promotes microphase separation and helps to improve the mechanical properties. By adjusting the soft-hard ratio and the imine content, a waterborne polyurethane film-forming agent that meets people's different needs can be designed. The highly symmetrical structure and C=N double bonds contained in the polyurethane are conducive to the improvement of mechanical properties.

[0045] Example 1 A method for preparing an aqueous polyurethane film-forming agent comprises the following steps: Weigh 1.65g of vanillin and dissolve it in 10mL of methanol. Weigh 1.07g of 4,4-diaminodiphenylmethane and dissolve it in 10mL of methanol. Add them to the reactor, mix them evenly, heat them to 65°C, and react them for 8h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash it with 10mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 80°C for 12h at a pressure of -0.01MPa. The mass of vanillin-based chain extender VSB is 2.2g, and the yield is 87%. Weigh 20g of polycarbonate and 10g of polyethylene glycol monomethyl ether, mix them evenly, heat them to 120°C, and dehydrate them under vacuum conditions for 2h. Cool down to 70℃, weigh 9.5g of isophorone diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, dibutyltin dilaurate), control the reaction temperature at 90℃, and stir the reaction for 2h. Add 2.2g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 90℃, and stir the reaction for 1h to obtain polyurethane resin. Transfer the obtained polyurethane resin to an emulsifying kettle, control the temperature of the polyurethane resin at 40℃, add 60.1g of deionized water under high-speed stirring, control the stirring rate at 1900rpm, and emulsify and disperse. After emulsification, weigh 2.3g of isophorone diamine and 5.0g of deionized water, slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain an aqueous polyurethane film-forming agent.

[0046] See 1 for the infrared spectrum of the vanillin-based chain extender prepared in Example 1 of the present invention. It can be seen from the figure that the VSB curve of the vanillin-based chain extender is at 1624 cm -1 The stretching vibration absorption peak of -C=N- appeared at 3370 cm -1 The -NH- bond at 1730 cm -1 The carbonyl stretching vibration peak on the aldehyde disappeared, indicating that the vanillin-based chain extender was successfully generated through the Schiff base reaction.

[0047] Figure 2 The vanillin-based chain extender prepared in Example 1 of the present invention 1 H NMR spectrum, from Figure 2 It can be seen that the H atom labeled e at 8.3 ppm in the chemical shift is the H atom connected to the C atom on the imine bond, indicating the successful formation of the imine bond with intrinsic self-healing properties, proving the successful synthesis of the vanillin-based chain extender.

[0048] Example 2 A method for preparing an aqueous polyurethane film-forming agent comprises the following steps: Weigh 2.38g of vanillin and dissolve it in 15mL of methanol. Weigh 1.55g of 4,4-diaminodiphenylmethane and dissolve it in 15mL of methanol. Add them to the reactor, mix them evenly, heat them to 65°C, and react them for 8h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash it with 15mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 80°C for 12h at a pressure of -0.01Mpa. The mass of vanillin-based chain extender VSB is 3.25g, and the yield is 89%. Weigh 20g of polycarbonate and 10g of polyethylene glycol monomethyl ether, mix them evenly, heat them to 120°C, and dehydrate them under vacuum conditions for 2h. Cool down to 70 ° C, weigh 10.4g of isophorone diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, dibutyltin dilaurate), control the reaction temperature at 90 ° C, and stir the reaction for 2h. Add 3.25g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 90 ° C, and stir the reaction for 1h to obtain a polyurethane resin. Transfer the obtained polyurethane resin to an emulsifier, control the temperature of the polyurethane resin at 40 ° C, add 43.6g of deionized water under high-speed stirring, and control the stirring rate at 2200rpm for emulsification and dispersion. After emulsification, weigh 2.53g of isophorone diamine and 4.1g of deionized water, slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain an aqueous polyurethane film-forming agent.

[0049] Figure 3 is a tensile stress-strain curve of the waterborne polyurethane film-forming agent in Example 2 of the present invention, from Figure 3 It can be seen that the stretching rate is 30 mm / min.

[0050] Example 3 A method for preparing an aqueous polyurethane film-forming agent comprises the following steps: Weigh 1.52g of vanillin and dissolve it in 10mL of methanol. Weigh 0.99g of 4,4-diaminodiphenylmethane and dissolve it in 10mL of methanol. Add them to the reactor, mix well, heat to 65°C, and react for 8h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash with 10mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 80°C for 12h at a pressure of -0.01MPa. The mass of vanillin-based chain extender VSB is 2.1g, and the yield is 90%. Weigh 20g of polycarbonate and 10g of polyethylene glycol monomethyl ether, mix well, heat to 120°C, and dehydrate under vacuum conditions for 2h. Cool down to 70 ° C, weigh 8.7g of isophorone diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, dibutyltin dilaurate), control the reaction temperature at 90 ° C, and stir the reaction for 2h. Add 2.1g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 90 ° C, and stir the reaction for 1h to obtain a polyurethane resin. Transfer the obtained polyurethane resin to an emulsifier, control the temperature of the polyurethane resin at 40 ° C, add 60g of deionized water under high-speed stirring, and control the stirring rate at 2000rpm for emulsification and dispersion. After emulsification, weigh 2.1g of isophorone diamine and 5.2g of deionized water, slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain an aqueous polyurethane film-forming agent.

[0051] Example 4 A method for preparing an aqueous polyurethane film-forming agent comprises the following steps: Weigh 3.12g of vanillin and dissolve it in 10mL of methanol. Weigh 2.03g of 4,4-diaminodiphenylmethane and dissolve it in 10mL of methanol. Add them to the reactor, mix them evenly, heat them to 65°C, and react them for 8h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash it with 10mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 80°C for 12h at a pressure of -0.01MPa. The mass of vanillin-based chain extender VSB is 4.4g, and the yield is 92%. Weigh 20g of polycarbonate and 10g of polyethylene glycol monomethyl ether, mix them evenly, heat them to 120°C, and dehydrate them under vacuum conditions for 2h. Cool down to 70℃, weigh 11.3g of isophorone diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, dibutyltin dilaurate), control the reaction temperature at 90℃, and stir the reaction for 2h. Add 4.4g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 90℃, and stir the reaction for 1h to obtain polyurethane resin. Transfer the obtained polyurethane resin to an emulsifier, control the temperature of the polyurethane resin at 40℃, add 65.5g of deionized water under high-speed stirring, and control the stirring rate at 1900rpm for emulsification and dispersion. After emulsification, weigh 2.73g of isophorone diamine and 8.0g of deionized water, slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain a water-based polyurethane film-forming agent.

[0052] Example 5 A method for preparing an aqueous polyurethane film-forming agent comprises the following steps: Weigh 0.29g of vanillin and dissolve it in 10mL of methanol. Weigh 0.19g of 4,4-diaminodiphenylmethane and dissolve it in 10mL of methanol. Add them to the reactor, mix well, heat to 65°C, and react for 8h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash with 10mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 80°C for 12h at a pressure of -0.01MPa. The mass of vanillin-based chain extender VSB is 0.41g, and the yield is 90%. Weigh 20g of polycarbonate and 10g of polyethylene glycol monomethyl ether, mix well, heat to 120°C, and dehydrate under vacuum conditions for 2h. Cool down to 70℃, weigh 8g of isophorone diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, stannous octoate), control the reaction temperature at 90℃, and stir the reaction for 2h. Add 0.41g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 90℃, and stir the reaction for 1h to obtain polyurethane resin. Transfer the obtained polyurethane resin to an emulsifying kettle, control the temperature of the polyurethane resin at 40℃, add 57.62g of deionized water under high-speed stirring, and control the stirring rate at 2000rpm for emulsification and dispersion. After emulsification, weigh 1.93g of isophorone diamine and 7.5g of deionized water, slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain an aqueous polyurethane film-forming agent.

[0053] Example 6 A method for preparing an aqueous polyurethane film-forming agent comprises the following steps: Weigh 0.29g of vanillin and dissolve it in 10mL of methanol. Weigh 0.19g of 4,4-diaminodiphenylmethane and dissolve it in 10mL of methanol. Add them to the reactor, mix well, heat to 55°C, and react for 6h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash with 10mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 60°C for 10h at a pressure of -0.05MPa. The mass of vanillin-based chain extender VSB is 0.41g, and the yield is 90%. Weigh 20g of polyhexanediol adipate and 10g of polytetrahydrofuran polyether diol, mix well, heat to 110°C, and dehydrate for 3h under vacuum conditions. Cool down to 70℃, weigh 8g of 2,4-toluene diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, dibutyltin di(dodecylsulfide)), control the reaction temperature at 80℃, and stir for 4h. Add 0.41g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 80℃, and stir for 2h to obtain polyurethane resin. Transfer the obtained polyurethane resin to an emulsifier, control the temperature of the polyurethane resin at 35℃, add 57.62g of deionized water under high-speed stirring, and control the stirring rate at 1500rpm for emulsification and dispersion. After emulsification, weigh 1.93g of ethylenediamine and 6.0g of deionized water, slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain a waterborne polyurethane film-forming agent.

[0054] Example 7 Weigh 0.29g of vanillin and dissolve it in 10mL of methanol. Weigh 0.19g of 4,4-diaminodiphenylmethane and dissolve it in 10mL of methanol. Add them to the reactor, mix well, heat to 65°C, and react for 10h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash with 10mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 70°C for 8h at a pressure of -0.1MPa. The mass of vanillin-based chain extender VSB is 0.41g, and the yield is 90%. Weigh 20g of poly (neopentyl adipate) and 10g of polyethylene glycol monomethyl ether, mix well, heat to 130°C, and dehydrate under vacuum conditions for 1h. Cool down to 70℃, weigh 8g of 2,6-toluene diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, dibutyltin diacetate), control the reaction temperature at 100℃, and stir for 3h. Add 0.41g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 100℃, and stir for 1.5h to obtain polyurethane resin. Transfer the obtained polyurethane resin to an emulsifier, control the temperature of the polyurethane resin at 45℃, add 57.62g of deionized water under high-speed stirring, and control the stirring rate at 2000rpm for emulsification and dispersion. After emulsification, weigh 1.93g of isophorone diamine and 10.1g of deionized water, slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain a water-based polyurethane film-forming agent.

[0055] Example 8 Weigh 0.29g of vanillin and dissolve it in 10mL of methanol. Weigh 0.19g of 4,4-diaminodiphenylmethane and dissolve it in 10mL of methanol. Add them to the reactor, mix well, heat to 65°C, and react for 10h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash with 10mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 70°C for 8h at a pressure of -0.1MPa. The mass of vanillin-based chain extender VSB is 0.41g, and the yield is 90%. Weigh 20g of poly (neopentyl adipate) and 10g of polyethylene glycol monomethyl ether, mix well, heat to 130°C, and dehydrate under vacuum conditions for 1h. Cool down to 70℃, weigh 8g of diphenylmethane diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, dibutyltin diacetate), control the reaction temperature at 100℃, and stir the reaction for 3h. Add 0.41g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 100℃, and stir the reaction for 1.5h to obtain polyurethane resin. Transfer the obtained polyurethane resin to an emulsifier, control the temperature of the polyurethane resin at 45℃, add 57.62g of deionized water under high-speed stirring, and control the stirring rate at 2000rpm for emulsification and dispersion. After emulsification, weigh 1.93g of isophorone diamine and 9.2g of deionized water, slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain a water-based polyurethane film-forming agent.

[0056] Example 9 Weigh 0.29g of vanillin and dissolve it in 10mL of methanol. Weigh 0.19g of 4,4-diaminodiphenylmethane and dissolve it in 10mL of methanol. Add them to the reactor, mix well, heat to 65°C, and react for 10h under nitrogen atmosphere to obtain the crude product of vanillin-based chain extender VSB. Wash with 10mL of methanol 3 times during vacuum filtration. The obtained bright yellow solid powder is placed in a vacuum drying oven and vacuum dried at 70°C for 8h at a pressure of -0.1MPa. The mass of vanillin-based chain extender VSB is 0.41g, and the yield is 90%. Weigh 20g of poly (neopentyl adipate) and 10g of polyethylene glycol monomethyl ether, mix well, heat to 130°C, and dehydrate under vacuum conditions for 1h. Cool down to 70℃, weigh 8g of 2,6-hexamethylene diisocyanate and add it to the reaction system, add 20μL of catalyst (0.02g, dibutyltin diacetate), control the reaction temperature at 100℃, and stir for 3h. Add 0.41g of vanillin-based chain extender VSB prepared above to the reaction system, control the reaction temperature at 100℃, and stir for 1.5h to obtain polyurethane resin. Transfer the obtained polyurethane resin to an emulsifier, control the temperature of the polyurethane resin at 45℃, add 57.62g of deionized water under high-speed stirring, and control the stirring rate at 2000rpm for emulsification and dispersion. After emulsification, weigh 1.93g of isophorone diamine and 6.5g of deionized water and slowly add them to the above-obtained emulsion and continue stirring for 1h to obtain a water-based polyurethane film-forming agent.

[0057] In summary, the present invention modifies the waterborne polyurethane emulsion by unsaturated dibasic acid, uses the modified polyurethane emulsion film-forming agent to prepare the wetting agent, and then applies it to the preparation of FRP products. The presence of benzene rings in the vanillin-based chain extender VSB improves the rigidity of the waterborne polyurethane film-forming agent attached to the surface of the glass fiber, increases the mechanical strength of the glass fiber, and the increase in the hard segment content promotes microphase separation, which helps to improve the mechanical properties. By adjusting the soft-hard ratio and the imine content, a waterborne polyurethane film-forming agent that meets different needs of people can be designed. The highly symmetrical structure and C=N double bonds contained in the polyurethane are conducive to the improvement of mechanical properties.

[0058] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A vanillin-based chain extender, characterized in that: The chemical structure is: 。 2. The method for preparing the vanillin-based chain extender according to claim 1, characterized in that: Vanillin, 4,4-diaminodiphenylmethane and methanol are mixed and reacted under a N2 atmosphere. After the reaction is completed, the mixture is filtered under reduced pressure, washed and dried to obtain a vanillin-based chain extender.

3. The method for preparing the vanillin-based chain extender according to claim 2, characterized in that: The usage ratio of the vanillin, 4,4-diaminodiphenylmethane and methanol is (0.08-0.8) mol: (0.04-0.4) mol: (50-300) mL.

4. The method for preparing the vanillin-based chain extender according to claim 2, characterized in that: The reaction temperature is 55-65° C., and the reflux reaction is carried out under N2 atmosphere for 6-10 hours; the washing condition is methanol washing; and the drying condition is vacuum drying at 60-80° C. for 8-12 hours.

5. A method for preparing an aqueous polyurethane film-forming agent, characterized in that: The preparation method adopts the vanillin-based chain extender obtained by the preparation method according to any one of claims 2 to 4 as a reaction raw material, comprising: mixing polyester polyol and polyether polyol, dehydrating, adding diisocyanate and organic tin catalyst under the protection of inert gas to carry out prepolymerization reaction to obtain polyurethane prepolymer; then adding the vanillin-based chain extender to carry out prepolymerization reaction to obtain polyurethane resin; then adding the first portion of deionized water during stirring to carry out emulsification reaction, and obtaining an aqueous polyurethane emulsion after the emulsification is completed; adding an amine chain extender to carry out post-chain extension reaction, adding the second portion of deionized water again, and stirring to obtain an aqueous polyurethane film-forming agent.

6. The method for preparing the aqueous polyurethane film-forming agent according to claim 5, characterized in that: The molar ratio of the polyester polyol to the polyether polyol is 1:1; The polyester polyol is one or two of polycarbonate, poly(hexanediol adipate) and poly(neopentyl adipate); the average molecular weight of the polycarbonate is 2000 g / mol, the average molecular weight of poly(hexanediol adipate) is 2000 g / mol, and the average molecular weight of poly(neopentyl adipate) is 2000 g / mol; The polyether polyol is at least one of polyethylene glycol monomethyl ether and polytetramethylene furan polyether diol; the average molecular weight of polyethylene glycol monomethyl ether is 1000 g / mol, and the average molecular weight of polytetramethylene furan polyether diol is 1000 g / mol; The vacuum degree of the dehydration is -0.01 to -0.1 MPa, the temperature of the dehydration is 110 to 130° C., and the time of the dehydration is 1 to 3 hours.

7. The method for preparing the aqueous polyurethane film-forming agent according to claim 5, characterized in that: The diisocyanate is at least one of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, 2,6-hexamethylene diisocyanate and isophorone diisocyanate; The organotin catalyst is at least one of dibutyltin dilaurate, stannous octoate, dibutyltin didodecylsulfide and dibutyltin diacetate; The mass fraction of the diisocyanate is 10% to 30%; The mass fraction of the organotin catalyst is 0.02%; The prepolymerization reaction temperature is 80-100°C and the time is 2-4h; The mass fraction of the vanillin-based chain extender is 1% to 9%; The prepolymerization reaction is carried out at a temperature of 80-100° C. and for a time of 1-2 hours.

8. The method for preparing the aqueous polyurethane film-forming agent according to claim 5, characterized in that: The amine chain extender is any one of isophoronediamine and ethylenediamine; The mass fraction of the amine chain extender is 1.10% to 7.05%; The temperature of the emulsification reaction is 35-45°C, and the stirring rate is 1500-2200rpm; The amount of the first portion of deionized water added is 40% to 50% of the total mass of the polyurethane resin, and the amount of the second portion of deionized water added is 5% to 10% of the total mass of the aqueous polyurethane emulsion.

9. An aqueous polyurethane film-forming agent, characterized in that: The method is prepared by any one of claims 5 to 8.

10. Use of the aqueous polyurethane film-forming agent prepared by the preparation method according to any one of claims 5 to 8 in the preparation of glass fiber drawing sizing, fabric sizing agent, leather finishing agent, carbon fiber sizing agent, adhesive or coating.

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