A xylitol-based hyperbranched polyurethane acrylate, its preparation method and application

Abstract

The present invention discloses a xylitol-based hyperbranched polyurethane acrylate, a preparation method thereof and an application thereof, relating to the technical field of waterborne self-extinguishing resins. The present invention uses the synthesized xylitol-based hyperbranched polyurethane acrylate to modify acrylate to prepare a waterborne self-extinguishing acrylate emulsion. The introduction of the xylitol-based hyperbranched polyurethane acrylate increases the crosslinking density of the emulsion and the particle size of the emulsion, resulting in a decrease in the glossiness of the obtained waterborne self-extinguishing acrylate. At the same time, due to the toughening effect of the hyperbranched structure, excellent mechanical properties are imparted to the coating film, overcoming the disadvantages of poor mechanical properties and high brittleness of the acrylate prepared by using short-chain small molecules as crosslinking agents. Moreover, due to the increase in the crosslinking density, the heat resistance stability, acid and alkali resistance and adhesion of the waterborne self-extinguishing acrylate are also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of waterborne self - extinction resins, and more specifically, to a xylitol - based hyperbranched polyurethane acrylate, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, low - gloss coatings have attracted increasing attention from consumers. Compared with high - gloss coatings, the coatings obtained from low - gloss coatings exhibit a softer and more natural appearance and can eliminate the adverse effects of glare. The methods for preparing matte coatings can be divided into physical matting and chemical matting. Physical matting includes two methods: surface post - treatment and adding matting agents. After surface treatment, a rough surface is mainly obtained through mechanical polishing, which is time - consuming and laborious; adding matting agents is the most commonly used method at present. Matting agents such as silica, diatomaceous earth, and clay are added to the polymer emulsion. During the film - forming process of the emulsion, the migration of the matting agent will produce a rough surface structure, reducing the gloss. Moreover, due to the incompatibility between the matting agent and the polymer emulsion, problems such as increased brittleness of the coating, poor handfeel, poor adhesion, and reduced storage stability of the coating will occur. Currently, most of the self - matting resins for waterborne coatings are waterborne polyurethanes, with relatively high costs.

[0003] The prior art discloses a waterborne self - matting acrylate - modified polyurethane resin and a preparation method thereof. The obtained waterborne self - matting acrylate - modified polyurethane resin has excellent heat resistance and does not lose the soft and elastic touch of polyurethane waterborne, with good handfeel and a matte - level surface gloss. However, the waterborne self - matting acrylate - modified polyurethane resin obtained by this method does not show improvement in film adhesion, acid - alkali resistance, and mechanical properties. Summary of the Invention

[0004] In order to overcome the deficiencies of poor film adhesion, acid - alkali resistance, tensile strength, and toughness of the existing waterborne self - matting coatings, the present invention provides a preparation method of a xylitol - based hyperbranched polyurethane acrylate. The xylitol - based hyperbranched polyurethane acrylate prepared by using this method is used to modify acrylate, which can comprehensively improve the mechanical properties, thermal stability, acid - alkali resistance, and adhesion of waterborne self - matting acrylate.

[0005] Another object of the present invention is to provide a xylitol - based hyperbranched polyurethane acrylate.

[0006] Another object of the present invention is to provide an application of a xylitol - based hyperbranched polyurethane acrylate in the preparation of waterborne self - matting acrylate.

[0007] Another object of the present invention is to provide a waterborne self - matting acrylate.

[0008] Another object of the present invention is to provide a preparation method of an aqueous self - extinguishing acrylate.

[0009] The above object of the present invention is achieved by the following technical solutions:

[0010] A preparation method of xylitol - based hyperbranched polyurethane acrylate, comprising the following steps:

[0011] S1. Under solvent - free conditions, xylitol, polyhydroxycarboxylic acid and a catalyst are fully reacted in an inert atmosphere. After full reaction, the pressure is reduced to - 0.09~ - 0.1 MPa, and the reaction is continued until the reaction is complete to obtain a hydroxyl - terminated hyperbranched polyester; the reaction temperature is 100~180 °C; the molar ratio of xylitol to polyhydroxycarboxylic acid is 1:(1~6);

[0012] S2. Diisocyanate, a catalyst, an inhibitor and a solvent are mixed, and hydroxyalkyl acrylate is added. After the reaction is complete, a prepolymer containing isocyanate groups is obtained; the addition rate of the hydroxyalkyl acrylate is 0.1~2 mL / min; the molar ratio of the diisocyanate to the hydroxyalkyl acrylate is 1:(0.5~1.5); the reaction temperature is 0~30 °C;

[0013] S3. The hydroxyl - terminated hyperbranched polyester obtained in S1 and a solvent are mixed, and the temperature is raised to 50~90 °C. After the hydroxyl - terminated hyperbranched polyester is dissolved, a catalyst is added, and then the prepolymer obtained in S2 is added. After the reaction is complete, xylitol - based hyperbranched polyurethane acrylate is obtained through post - treatment; the addition rate of the prepolymer is 0.1~2 mL / min; the molar ratio of the hydroxyl - terminated hyperbranched polyester to the prepolymer is 1:(4~14).

[0014] It should be noted that:

[0015] Xylitol has a polyhydroxy structure. 1 mole of xylitol has 5 moles of hydroxyl groups, with high reaction activity. It can be used as a core molecule to carry out polycondensation reaction with polyhydroxycarboxylic acid to prepare a hydroxyl - terminated hyperbranched polyester with a highly branched structure, and then react with an isocyanate - containing intermediate to prepare xylitol - based hyperbranched polyurethane acrylate. Since the molecular structure of xylitol is mainly composed of short chains, the prepared hyperbranched polyurethane acrylate has a compact structure and a high degree of branching, approaching the spherical structure of dendritic molecules. Using the prepared xylitol - based hyperbranched polyurethane acrylate to modify aqueous self - extinguishing acrylate can utilize its characteristics of high functionality, high degree of branching and the presence of hydrogen bonds in the molecule to improve the mechanical properties, heat resistance and chemical resistance of the acrylate.

[0016] The reaction described in S1 is carried out in an inert atmosphere, which can prevent side reactions from occurring and ensure the smooth progress of the polycondensation reaction of xylitol and polyhydroxycarboxylic acid. After the reaction for 1 - 4 h, reduced pressure is applied to remove the water generated in the polycondensation reaction and ensure the continuous progress of the polycondensation reaction. The magnitude of the pressure will affect the degree of progress of the polycondensation reaction. In S1, it is also necessary to strictly control the molar ratio of xylitol to polyhydroxycarboxylic acid because the molar ratio of the two will affect the generation number and branching degree of the prepared hydroxyl - terminated hyperbranched polyester.

[0017] In S2, controlling the addition rate of hydroxyalkyl acrylate is to control the reaction rate and avoid the reaction from proceeding too fast, resulting in a rapid increase in the reaction temperature and the self - polymerization of the double bond of hydroxyalkyl acrylate, making the reaction unable to proceed smoothly. Preferably, the addition rate of the hydroxyalkyl acrylate is 0.2 - 0.8 mL / min, and more preferably 0.4 mL / min. The molar ratio of diisocyanate to hydroxyalkyl acrylate will affect the content of isocyanate groups and double bonds in the prepolymer containing isocyanate groups, so it needs to be reasonably controlled. In addition, the reaction in S2 is carried out at a lower temperature to control the reaction of hydroxyalkyl acrylate with only one isocyanate group on the diisocyanate. Preferably, the reaction temperature is 0 - 15 °C.

[0018] The reflux and temperature increase in S3 are to fully dissolve the hydroxyl - terminated hyperbranched polyester and enable it to react fully with the prepolymer in S2 later. Among them, the temperature will affect the reaction rate. Preferably, the temperature is 65 - 85 °C. In addition, the addition rate of the prepolymer will also affect the reaction rate. If the dropping rate is too fast, the reaction rate will be too fast, the temperature will rise rapidly, and the double bond of the prepolymer will undergo self - polymerization. Preferably, the addition rate is 0.5 - 1 mL / min, and more preferably 0.8 mL / min. The molar ratio of the hydroxyl - terminated hyperbranched polyester to the prepolymer will affect the double - bond content of the hyperbranched polyurethane acrylate.

[0019] The catalyst addition amount in S1 is 0.1 - 1% of the total mass of xylitol, polyhydroxycarboxylic acid, and the catalyst, preferably 0.3 - 0.7%, and more preferably 0.5%.

[0020] The addition amounts of the catalyst, inhibitor, and solvent in S2 are 0.1 - 1%, 0.5 - 1.5%, and 30 - 70% of the total mass of diisocyanate, catalyst, inhibitor, solvent, and hydroxyalkyl acrylate, respectively; preferably 0.1 - 0.4%, 0.5 - 1%, and 40 - 60%; more preferably 0.15%, 0.6%, and 50%.

[0021] The addition amounts of the catalyst and solvent in S3 are 0.1 - 1% and 30 - 70% of the total mass of hydroxyl - terminated hyperbranched polyester, prepolymer, solvent, and catalyst, respectively; preferably 0.3 - 0.7% and 40 - 60%; more preferably 0.5% and 50%.

[0022] Controlling the addition amounts of the catalyst, inhibitor and solvent in each step is conducive to better controlling the reaction rate and enabling the reaction to proceed smoothly and steadily.

[0023] Preferably, the molar ratio of xylitol to polyhydroxycarboxylic acid in S1 is 1:(2-4), more preferably 1:3.

[0024] Preferably, the molar ratio of diisocyanate to hydroxyalkyl acrylate in S2 is 1:(0.8-1.1), more preferably 1:1.

[0025] Preferably, the molar ratio of the terminal hydroxyl hyperbranched polyester to the prepolymer in S3 is 1:(6-10), more preferably 1:8.

[0026] Specifically, in S1, the polyhydroxycarboxylic acid is one or more of dimethylolbutyric acid, dimethylolpropionic acid, and dihydroxycinnamic acid; the catalyst is one or more of p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, and concentrated sulfuric acid.

[0027] Specifically, in S2 and S3, the diisocyanate is one or more of isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and dicyclohexylmethane diisocyanate; the hydroxyalkyl acrylate is one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; the catalyst is one or more of dibutyltin dilaurate, butyltin acid, bis(dimethylaminoethyl) ether, titanium tetraisopropoxide, and zinc naphthenate; the inhibitor is one or more of p-methoxyphenol, hydroquinone, diphenylamine, and nitrobenzene; the solvent is one or more of 1,4-dioxane, dimethyl sulfoxide, N,N-dimethylformamide, and toluene.

[0028] Specifically, the sufficient reaction in S1 is for 1-4 h.

[0029] Specifically, the post-treatment in S2 is freeze-drying under vacuum.

[0030] The present invention selects xylitol as a raw material to prepare polyurethane acrylate. Not only can a polyurethane acrylate with a high degree of branching be obtained, but xylitol is a renewable bio-based material, which is more environmentally friendly and conforms to the concept of green sustainable development. By controlling conditions such as temperature and addition amount in each step, the reaction is ensured to proceed smoothly, and a xylitol-based hyperbranched polyurethane acrylate with a certain degree of branching is obtained.

[0031] The present invention protects a xylitol-based hyperbranched polyurethane acrylate prepared by the above preparation method.

[0032] Specifically, the degree of branching of the xylitol-based hyperbranched polyurethane acrylate is 0.4 to 0.6.

[0033] The degree of branching of the xylitol-based hyperbranched polyurethane acrylate obtained in the present invention is 0.4 to 0.6. When preparing the waterborne self-extinguishing acrylate, the hyperbranched structure in the xylitol-based hyperbranched polyurethane acrylate can improve the crosslinking density of the acrylate while enhancing the mechanical properties of the waterborne self-extinguishing acrylate film. Moreover, the obtained waterborne self-extinguishing acrylate has a stable structure, good acid and alkali resistance, and good thermal stability.

[0034] Hyperbranched polymers are composed of three repeating units: terminal units (T), dendritic units (D), and linear units (L). The degree of branching (DB) is an important parameter for measuring the density of branching points. The DB of an ideal dendritic polymer is equal to 1, while the DB of a hyperbranched polymer is between 0 and 1. The DB can be calculated by 13 the integration of the peaks corresponding to the linear unit (L), terminal unit (T), and dendritic unit (D) in the quaternary carbon region of the 13C NMR spectrum.

[0035] The DB calculation formula is: DB = (D + T) / (D + L + T), where L, T, and D are the integrals of the peaks of the linear unit (L), terminal unit (T), and dendritic unit (D), respectively.

[0036] 13 The three quaternary carbon atom peaks at 46 - 51 PPM in the 13C NMR spectrum represent the linear unit, terminal unit, and dendritic unit respectively. Based on the integration of the three peaks, the degree of branching can be calculated according to the DB calculation formula.

[0037] The present invention also protects the use of the above xylitol-based hyperbranched polyurethane acrylate in the preparation of waterborne self-extinguishing acrylate.

[0038] The present invention particularly protects a waterborne self-extinguishing acrylate, which is obtained by subjecting an acrylate mixed monomer and the above xylitol-based hyperbranched polyurethane acrylate to a free radical polymerization reaction;

[0039] wherein, the mass fraction of the acrylate mixed monomer is 40 - 120 parts, and the mass fraction of the xylitol-based hyperbranched polyurethane acrylate is 0.2 - 4 parts.

[0040] The present invention uses the above xylitol-based hyperbranched polyurethane acrylate and acrylate mixed monomer to prepare the waterborne self-extinguishing acrylate. The obtained waterborne self-extinguishing acrylate has good stability, and its gloss, adhesion, tensile strength, and toughness are all improved. Moreover, the raw materials are environmentally friendly and the cost is relatively low, and it can be widely used in fields such as wall coatings, furniture coatings, leather coatings, and automotive interior coatings.

[0041] Specifically, in the radical polymerization reaction, 0.2 to 7 parts by mass of an emulsifier is added, preferably 0.2 to 4 parts by mass.

[0042] By controlling the amount of the emulsifier, the gloss of the waterborne self - extinguishing acrylate can be regulated.

[0043] Specifically, in the radical polymerization reaction, 0.2 to 0.9 parts by mass of an initiator and 100 to 300 parts by mass of deionized water are also added.

[0044] The present invention also protects a preparation method of the above - mentioned waterborne self - extinguishing acrylate, which comprises the following steps:

[0045] S1. Add deionized water and the emulsifier into a closed container, and mix them evenly under the temperature condition of 30 to 60 °C;

[0046] S2. Add the acrylate mixed monomer and xylitol - based hyperbranched polyurethane acrylate into a closed container, mix them evenly, and maintain the temperature at 30 to 60 °C;

[0047] S3. Raise the temperature to 70 to 95 °C, add the initiator into the closed container at a rate of 2 to 12 mL / h, and obtain the waterborne self - extinguishing acrylate after post - treatment after the reaction is complete.

[0048] Among them, in S1 and S2, by controlling the temperature, the acrylate mixed monomer and xylitol - based hyperbranched polyurethane acrylate can be fully emulsified; in S3, raising the temperature is to reach the initiation temperature of the radical polymerization reaction. In addition, in S3, the addition rate of the initiator also needs to be controlled to avoid a too fast reaction rate and the generation of a large amount of gel; preferably, the addition rate is 5 to 10 mL / h, and more preferably 8 mL / h.

[0049] Specifically, the acrylate mixed monomer is one or more of butyl acrylate, ethyl acrylate, methyl acrylate, isooctyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isooctyl methacrylate;

[0050] The emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, dodecylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isomeric alcohol polyoxyethylene ether, OP - 10 emulsifier;

[0051] Specifically, the emulsifier can adopt a non - ionic emulsifier (such as OP - 10 emulsifier), and sodium dodecyl sulfate is an anionic emulsifier. The compounding of the two can improve the emulsification effect and the stability of the emulsion.

[0052] The initiator is potassium persulfate or ammonium persulfate.

[0053] The waterborne self - extinguishing acrylate prepared by the present invention is in the form of an emulsion.

[0054] Specifically, the post - treatment in S2 includes cooling, neutralization, and filtration. Among them, neutralization is carried out by adding a neutralizing agent, and the mass fraction of the neutralizing agent is 0.5 - 2.5 parts.

[0055] The neutralizing agent is one or more of ammonia water, triethylamine, and N,N - dimethylethanolamine.

[0056] For the parts not specifically described in the present invention, selection can be made according to the conventional conditions in the art.

[0057] Compared with the prior art, the present invention has at least the following beneficial effects:

[0058] The present invention provides a preparation method of xylitol - based hyperbranched polyurethane acrylate. The synthesized xylitol - based hyperbranched polyurethane acrylate is used to modify acrylate to prepare waterborne self - extinguishing acrylate. The introduction of xylitol - based hyperbranched polyurethane acrylate increases the cross - linking density of the emulsion and the particle size of the emulsion, resulting in a decrease in the gloss of the obtained waterborne self - extinguishing acrylate. At the same time, due to the toughening effect of the hyperbranched structure, the coating film is endowed with excellent mechanical properties, overcoming the disadvantages of poor mechanical properties and high brittleness of the acrylate prepared by using short - chain small molecules as cross - linkers. Moreover, due to the increase in cross - linking density, the heat - resistant stability, acid and alkali resistance, and adhesion of the waterborne self - extinguishing acrylate are also improved. In addition, the present invention can also control the gloss of the waterborne self - extinguishing acrylate by adjusting the addition amount of the emulsifier.

[0059] The adhesion of the waterborne self - extinguishing acrylate obtained in the present invention is above 5B, the tensile strength is above 13 MPa, the elongation at break is above 968%, the 5wt% weight loss temperature reaches 351.2 °C, the acid resistance reaches 0.41%, and the alkali resistance reaches 1.32%. Specific Embodiments

[0060] In the examples and comparative examples of the present invention, the 13 13C NMR spectrum was tested by an AVANCEIII HD600MHz (Bruker, Switzerland) NMR instrument, using DMSO - d6 as the solvent and tetramethylsilane (TMS) as the internal standard.

[0061] The following further illustrates the present invention in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw material reagents used in the embodiments of the present invention are conventional raw material reagents purchased.

[0062] Example 1

[0063] A preparation method of xylitol-based hyperbranched polyurethane acrylate, comprising the following steps:

[0064] S1. Under solvent-free conditions, add 50 g of xylitol, 132 g of dimethylolpropionic acid, and 0.9 g of p-toluenesulfonic acid to a reaction kettle, introduce nitrogen, stir and react at 170 °C under normal pressure for 2 h, then stop introducing nitrogen, reduce the pressure to -0.097 MPa, and continue to react under vacuum for 2 h to obtain a light yellow solid xylitol-terminated hydroxy hyperbranched polyester;

[0065] Among them, the molar ratio of xylitol to dimethylolpropionic acid is 1:3; the mass percentage of p-toluenesulfonic acid is 0.5%;

[0066] S2. Add 40 g of isophorone diisocyanate, 0.6 g of dibutyltin dilaurate, 0.7 g of p-methoxyphenol, and 62 g of dioxane to a reaction kettle, control the temperature of the reaction kettle at 10 °C, and gradually add 21 g of hydroxyethyl acrylate dropwise at a certain speed. After adding, react under normal pressure for 3 h to obtain a red-brown liquid isocyanate-terminated prepolymer;

[0067] Among them, the molar ratio of isophorone diisocyanate to hydroxyethyl acrylate is 1:1; the addition speed of hydroxyethyl acrylate is 0.4 mL / min; the mass percentages of dibutyltin dilaurate, p-methoxyphenol, and dioxane are 0.5%, 0.6%, and 50% respectively;

[0068] S3. Add 10 g of xylitol-terminated hydroxy hyperbranched polyester, 50 g of dioxane, and 0.5 g of dibutyltin dilaurate to a reaction kettle, control the temperature of the reaction kettle at 80 °C, and gradually add 40 g of isocyanate-terminated prepolymer dropwise to the reaction kettle at a certain speed. After adding, react under normal pressure for 4 h, and obtain white powdery hyperbranched polyurethane acrylate after freeze-drying under vacuum for 24 h;

[0069] Among them, the molar ratio of the hydroxy-terminated hyperbranched polyester to the prepolymer is 1:8; the addition speed of the prepolymer is 0.8 ml / min; the mass percentages of dibutyltin dilaurate and dioxane are 0.5% and 50% respectively.

[0070] The degree of branching of the xylitol-based hyperbranched polyurethane acrylate prepared above is 0.60.

[0071] The water-based self-extinguishing acrylate prepared from the above xylitol-based hyperbranched polyurethane acrylate, the water-based self-extinguishing acrylate is obtained by free radical polymerization of butyl acrylate and xylitol-based hyperbranched polyurethane acrylate. Among them, the mass fraction of the acrylate mixed monomer is 100 parts, and the mass fraction of the xylitol-based hyperbranched polyurethane acrylate is 0.2 parts;

[0072] The specific preparation method includes the following steps:

[0073] S1. Add 180 parts by mass of deionized water, 1 part of OP-10 emulsifier and 1 part of sodium dodecyl sulfate into a reaction kettle, heat up to 35 °C, and stir at a speed of 120 r / min for 20 min;

[0074] S2. Add 60 parts by mass of methyl methacrylate and 40 parts of butyl acrylate into the reaction kettle, heat up to 45 °C, and stir at a speed of 600 r / min for 45 min;

[0075] S3. Adjust the speed to 300 r / min, heat up to 70 °C, dissolve 0.6 part by mass of potassium persulfate in 20 parts of deionized water to prepare an aqueous solution of potassium persulfate, and add the aqueous solution of potassium persulfate dropwise into the reaction kettle within 3 h. After adding, continue to react for 2 h, cool to room temperature, add 0.7 part by mass of triethylamine for neutralization, and finally filter through a 200-mesh filter to obtain a light blue emulsion; among them, the addition rate of potassium persulfate is 8 ml / h.

[0076] Examples 2 to 14

[0077] A preparation method of xylitol-based hyperbranched polyurethane acrylate, the steps are the same as those in Example 1, and the differences are shown in Table 1; among them, the degrees of branching of the xylitol-based hyperbranched polyurethane acrylate prepared in Examples 2 to 14 are 0.40, 0.42, 0.46, 0.45, 0.48, 0.51, 0.57, 0.55, 0.54, 0.58, 0.56, 0.51, 0.52 respectively.

[0078] Table 1. Preparation parameters of xylitol-based hyperbranched polyurethane acrylate

[0079]

[0080]

[0081]

[0082] The waterborne self-extinguishing acrylate prepared from the above xylitol-based hyperbranched polyurethane acrylate, the formula is shown in Table 2, and the preparation method is the same as that in Example 1, and the differences are shown in Table 3.

[0083] Table 2. Formula of waterborne self-extinguishing acrylate

[0084]

[0085] Table 3. Preparation parameters of waterborne self-extinguishing acrylate

[0086]

[0087]

[0088] Example 15

[0089] An aqueous self - extinction acrylate is prepared from the xylitol - based hyperbranched polyurethane acrylate of Example 2. The preparation method is the same as that of Example 2, except that the addition amount of the emulsifier is 0.2 parts.

[0090] Example 16

[0091] An aqueous self - extinction acrylate is prepared from the xylitol - based hyperbranched polyurethane acrylate of Example 3. The preparation method is the same as that of Example 3, except that the addition amount of the emulsifier is 1 part.

[0092] Comparative Example 1

[0093] An aqueous self - extinction acrylate, the preparation method is the same as that of Example 1, except that the xylitol - based hyperbranched polyurethane acrylate of Example 1 is not added.

[0094] Comparative Example 2

[0095] A preparation method of an aqueous self - extinction acrylate - modified polyurethane resin includes the following steps:

[0096] S1. Preparation of pre - emulsion: Dissolve the emulsifier in deionized water and stir evenly at a speed of 400 RPM. Then add the functional monomer and monomer to it and carry out emulsification for 60 min to obtain the pre - emulsion. Among them, the mass of deionized water used in this step is 40% of the total mass of deionized water in the raw material ratio;

[0097] S2. Preparation of initiator solution: Dissolve the initiator in deionized water to obtain the initiator solution. Among them, the mass of deionized water used in this step is 5% of the total mass of deionized water in the raw material ratio;

[0098] S3. Preparation of acrylic emulsion: Add the remaining deionized water to the reaction kettle, heat it to 80 °C at a speed of 400 RPM, and simultaneously and uniformly drop - wise add the pre - emulsion and the initiator solution to it. The pre - emulsion is uniformly dropped - wise added within 1.5 - 4 hours, and the initiator solution is uniformly dropped - wise added within 2 hours. During the dropping process, maintain a speed of 800 RPM and control the temperature at 75 °C. After the pre - emulsion and the initiator solution are dropped - wise added, maintain the temperature at 85 °C for heat preservation for 0.5 hours, then heat it up to 95 °C for heat preservation for 0.5 hours, and then cool it to 50 °C to obtain the acrylic emulsion containing amino groups;

[0099] S4. Add the polyol into the reaction kettle. After heating up to 110 °C, start to evacuate the air, dehydrate under vacuum for 4 h, then fill in N2, and cool down to 80 °C. Add the polyisocyanate and the catalyst into it, keep the temperature for reaction for 3 h, then heat up to 90 °C and react for 2 h. During the reaction process, intermittently add the solvent (adding the solvent in this step is to reduce the viscosity of the system and ensure the rapid progress of the reaction). After the reaction, obtain the prepolymer with isocyanate group at the end.

[0100] S5. Add the acrylic emulsion obtained in S3 into a high-speed disperser with a rotation speed of 1000 RPM, and also add the prepolymer obtained in S4 into it for chain extension. After the chain extension is completed, add the end-capping agent and react for 0.5 h, and start to evacuate the air. Remove the solvent under vacuum, then cool down to room temperature, and thus obtain the waterborne self-extinguishing acrylate-modified polyurethane resin.

[0101] Comparative Example 3

[0102] A kind of waterborne self-extinguishing acrylate, the preparation method is the same as that of Example 1, the difference is that the hyperbranched unsaturated polyester obtained by conventional purchase on the market is used to replace the xylitol-based hyperbranched polyurethane acrylate, and the branching degree of the hyperbranched unsaturated polyester is 0.45.

[0103] Result Detection

[0104] Use a coating rod to evenly coat the waterborne self-extinguishing acrylate emulsion obtained in the examples and comparative examples on the glass sheet to form a wet film of 200 μm, dry it in a blast drying oven at 60 °C for 24 h to form a film, and store the film in a desiccator after tearing it off to prepare for the next performance test.

[0105] Thermogravimetric analysis: Measure by using the STA409PC instrument of Netzsch, Germany. The measurement conditions are heating from 30 °C to 600 °C at a heating rate of 10 °C / min under a nitrogen flow rate of 25 mL / min.

[0106] Glossiness test: According to ISO 2813, use the HG60S glossiness meter of Shenzhen 3nh Technology Co., Ltd. to measure the glossiness of the self-extinguishing acrylate film at an incident angle of 60°. Measure each sample ten times and record the average result. The smaller the value, the smaller the glossiness.

[0107] Mechanical property test: Use the electronic universal testing machine of SUST model in Zhuhai, China to test the mechanical properties of the film at a tensile speed of 20 mm / min at 25 °C; the sample is made into a dumbbell shape with dimensions of 75×4×0.5 mm.

[0108] Comprehensive performance test: The adhesion, pencil hardness, and flexibility of the film were measured according to ASTM D3359, ASTM D3363, and ASTM D522, respectively. The chemical resistance of the film was tested according to GB / T 1763-1979 and expressed as the weight loss rate of the film. The film was immersed in aqueous solutions of 10 wt% HCl and 10 wt% NaOH at room temperature for 24 h, then the film was taken out and dried to a constant weight, weighed, and its weight loss rate was calculated.

[0109] The results are shown in Tables 4 and 5.

[0110] Table 4. Performance test results of waterborne self-extinguishing acrylate of Examples 1-14 and Comparative Examples 1-3

[0111]

[0112]

[0113] Table 5. Performance test results of waterborne self-extinguishing acrylate of Examples 2-3 and Examples 15-16

[0114] Test Items Example 2 Example 3 Example 15 Example 16 60° Glossiness 87.3 62.5 11.6 12.6 Tensile Strength (MPa) 10.42 10.56 10.34 10.48 Elongation at Break (%) 642.12 649.31 638.21 650.42 Fracture Energy (MPa) 45.34 46.54 44.67 46.51 5wt% Weight Loss Temperature (°C) 346.5 346.9 345.7 347.3 10wt% Weight Loss Temperature (°C) 359.7 360.8 359.5 361.2 Pencil Hardness H H H H Adhesion 4B 4B 4B 4B Flexibility (mm) 1 1 1 1 HCl Resistance (%) 1.23 1.43 1.27 1.38 NaOH Resistance (%) 2.41 2.65 2.38 2.61

[0115] It can be seen from Table 4 that the amount of emulsifier used is the main factor affecting the gloss, and the gloss can be regulated by controlling the amount of emulsifier used; compared with the comparative examples, modifying acrylate with xylitol-based hyperbranched polyurethane acrylate can significantly improve the mechanical properties, thermal stability, acid and alkali resistance, and adhesion of the coating film, among which the elongation at break and fracture energy are improved most significantly. This is mainly because the addition of xylitol-based hyperbranched polyurethane acrylate can not only increase the crosslinking density of the film but also has an internal plasticizing effect. Example 1 exhibits the best performance, with a tensile strength, elongation at break, fracture energy, adhesion, 5 wt% weight loss temperature, and 60° gloss of 13.68 MPa, 968.32%, 74.93 MPa, 5B, 351.2 °C, and 13.6, respectively.

[0116] It can be seen from Table 5 that by comparing Examples 2 and 15, and Examples 3 and 16, it can be known that the change in the amount of emulsifier added will affect the gloss of the waterborne self-extinguishing resin. This is because the decrease in the amount of emulsifier used will increase the particle size of the emulsion, and the increase in particle size helps to form a rough surface, resulting in a decrease in gloss, but it has no significant effect on other properties.

[0117] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A preparation method of xylitol-based hyperbranched polyurethane acrylate, characterized in that, It includes the following steps: S1. Under solvent-free conditions, xylitol, polyhydroxycarboxylic acid and a catalyst are fully reacted in an inert atmosphere. After full reaction, the pressure is reduced to -0.09 to -0.1 MPa, and the reaction is continued until the reaction is complete to obtain a hydroxyl-terminated hyperbranched polyester; the reaction temperature is 100 to 180 °C; the molar ratio of xylitol to polyhydroxycarboxylic acid is 1:(1 - 6); S2. Diisocyanate, a catalyst, an inhibitor and a solvent are mixed, and hydroxyalkyl acrylate is added. After the reaction is complete, a prepolymer containing an isocyanate group is obtained; the addition rate of the hydroxyalkyl acrylate is 0.1 to 2 mL / min; the molar ratio of the diisocyanate to the hydroxyalkyl acrylate is 1:(0.5 - 1.5); the reaction temperature is 0 to 30 °C; S3. The hydroxyl-terminated hyperbranched polyester obtained in S1 and a solvent are mixed, heated to 50 to 90 °C. After the hydroxyl-terminated hyperbranched polyester is dissolved, a catalyst is added, and then the prepolymer obtained in S2 is added. After the reaction is complete, xylitol-based hyperbranched polyurethane acrylate is obtained through post-treatment; the addition rate of the prepolymer is 0.1 to 2 mL / min; the molar ratio of the hydroxyl-terminated hyperbranched polyester to the prepolymer is 1:(4 - 14); Among them, in step S1, the polyhydroxycarboxylic acid is one or both of dimethylolbutyric acid and dimethylolpropionic acid; In step S3, the branching degree of the xylitol-based hyperbranched polyurethane acrylate is 0.4 to 0.

6.

2. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of xylitol to polyhydroxycarboxylic acid is 1:(2 - 4).

3. The preparation method according to claim 1, wherein In S2, the molar ratio of the diisocyanate to the hydroxyalkyl acrylate is 1:(0.8 - 1.1).

4. The preparation method according to claim 1, characterized in that, In S3, the molar ratio of the hydroxyl-terminated hyperbranched polyester to the prepolymer is 1:(6 - 10).

5. A xylitol-based hyperbranched polyurethane acrylate prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the xylitol-based hyperbranched polyurethane acrylate according to claim 5 in the preparation of a waterborne self-extinguishing acrylate.

7. An aqueous self - extinguishing acrylate, characterized in that, The waterborne self-extinguishing acrylate is obtained by a free radical polymerization reaction of an acrylate mixed monomer and the xylitol-based hyperbranched polyurethane acrylate according to claim 5; Among them, the mass fraction of the acrylate mixed monomer is 40 to 120 parts, and the mass fraction of the xylitol-based hyperbranched polyurethane acrylate is 0.2 to 4 parts; In the free radical polymerization reaction, 0.2 to 7 parts of an emulsifier are added by mass.

8. A preparation method of the waterborne self - extinguishing acrylate according to claim 7, characterized in that, It includes the following steps: S1. Deionized water and an emulsifier are added to a closed container and mixed evenly under the temperature condition of 30 to 60 °C; S2. The acrylate mixed monomer and the xylitol-based hyperbranched polyurethane acrylate are added to a closed container, mixed evenly, and the temperature is maintained at 30 to 60 °C; S3. The temperature is raised to 70 to 90 °C, and the initiator is added to the closed container at a rate of 2 to 12 mL / h. After the reaction is complete, a waterborne self-extinguishing acrylate is obtained through post-treatment.

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