Anti-ultraviolet bio-based polyurethane sizing agent and preparation method thereof

Abstract

The invention relates to an anti-ultraviolet bio-based waterborne polyurethane sizing agent synthesized by introducing a neutralizing agent and a preparation method of the anti-ultraviolet bio-based waterborne polyurethane sizing agent, and belongs to the technical field of sizing agents. The waterborne polyurethane sizing agent is prepared from the following components in parts by weight: 1 to 5 parts of bio-based polyurethane, 0.5 to 10 parts of a neutralizing agent and 90 to 98.5 parts of deionized water, the structural formula of the polyurethane is as shown in formula 1. The sizing agent not only can effectively improve the interface adhesion of the carbon fiber and nylon 6 resin composite material, but also has excellent ultraviolet resistance. The preparation method of the waterborne polyurethane sizing agent comprises the following steps: (1) carrying out two-step reaction and chemical conversion on vegetable oil to generate bio-based polyol; (2) synthesizing a polyurethane prepolymer by utilizing a bio-based raw material; (3) adding a neutralizing agent with an anti-ultraviolet function to prepare a bio-based polyurethane sizing agent; the sizing agent can effectively improve the interface bonding capacity of a carbon fiber nylon 6 matrix resin composite material and improve the ultraviolet resistance of the composite material, so that the service life is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of sizing agents, and particularly relates to a water-based bio-based polyurethane sizing agent with anti-ultraviolet performance and a preparation method thereof. Background Art

[0002] Carbon fiber has excellent properties such as high strength, high specific modulus, high temperature resistance, durability, light weight, corrosion resistance and radiation resistance, electrical conductivity, heat transfer, and shock absorption. These properties make it very suitable for cutting-edge fields such as aerospace, medical and military sectors. Therefore, extensive research efforts are focused on the development of high-performance CF composites with various matrices.

[0003] The inherent smoothness of the CF surface, coupled with its natural chemical inertness, leads to its insufficient interfacial properties, which greatly limits its potential application prospects. The interfacial bonding strength between the fiber and the resin matrix can be improved through carbon fiber surface modification methods such as electrophoretic deposition, chemical grafting and sizing, thereby improving the comprehensive mechanical properties of the composite material. The sizing method is not only safe and simple to operate, but also can avoid contamination of the carbon fiber surface, protect the activity of the surface groups, improve the fiber bundling, and also can wet the carbon fiber, reduce the surface tension between the carbon fiber and the matrix resin, and enhance the interfacial bonding strength between the carbon fiber and the matrix resin, thereby improving the mechanical properties of the composite material. However, most of the commercial sizing agents today are thermosetting sizing agents, which are not compatible with the heat resistance of thermoplastic resins. Nylon 6 is a thermoplastic resin with an amide bond as the repeating unit. It has the advantages of low price and wide application, and it has polar groups itself, so the development of sizing agents suitable for nylon 6 has good application prospects.

[0004] Bio-based polymers have attracted widespread attention due to their pollution-free raw material sources and low cost. According to the principle of like dissolves like, bio-based polyurethane has good compatibility with nylon due to its similar structure to the nylon matrix. After sizing the carbon fiber surface with polyurethane, a good interface layer can be formed between the carbon fiber and nylon, effectively improving the mechanical properties of carbon fiber / nylon composites. In the traditional polyurethane synthesis process, non-renewable petroleum-based raw materials are usually used, and the reaction process is prone to produce toxic substances. In addition, polyurethane will undergo free radical photooxidative degradation under light irradiation. It is unstable and easy to decompose under long-term light and extreme environments, thus affecting the service life of the composite material. Therefore, the development of a water-based thermoplastic sizing agent that is UV-resistant and bio-based for nylon 6 resin is of great significance to the development of the carbon fiber industry. Summary of the invention

[0005] The purpose of the present invention is to provide an aqueous bio-based polyurethane sizing agent with anti-ultraviolet performance and a preparation method thereof, wherein the sizing agent can not only effectively improve the interface bonding ability of carbon fiber nylon six resin composite materials, but also has excellent anti-ultraviolet performance.

[0006] The present invention first provides a water-based bio-based polyurethane sizing agent with UV resistance, which comprises, by weight:

[0007] 1-5 parts of bio-based polyurethane, 0.5-10 parts of neutralizer, 90-98.5 parts of deionized water;

[0008] The structural formula of the UV-resistant bio-based polyurethane is shown in Formula 1:

[0009]

[0010] In Formula 1, the value range of n is 20 to 80.

[0011] The present invention also provides a method for preparing a water-based bio-based polyurethane sizing agent with UV resistance, comprising the following steps:

[0012] Step 1: Preparation of bio-based polyols

[0013] First, the vegetable oil and diethanolamine were reacted under alkaline conditions with nitrogen for 4 hours, and the post-treated product was reacted with butanediol under acidic conditions with nitrogen at 180°C;

[0014] Step 2: Preparation of bio-based polyurethane prepolymer

[0015] Bio-based polyol, diisocyanate, dimethylaminopropylene glycol and a catalyst are dissolved in a solvent, nitrogen is passed through, and the reaction is carried out at 70° C. to 80° C. for 2 to 4 hours to obtain a polyurethane prepolymer, and the solvent is removed by rotary evaporation and dried to obtain a bio-based polyurethane;

[0016] Step 3: Preparation of waterborne bio-based polyurethane sizing agent with UV resistance

[0017] The bio-based polyurethane obtained in step 2 is dispersed in water under high-speed stirring, and a neutralizing agent, bio-based phenolic acid, is added dropwise to react to obtain a water-based bio-based polyurethane sizing agent with anti-ultraviolet performance.

[0018] Preferably, the bio-based phenolic acid compound is one of salicylic acid, gallic acid, ferulic acid or gentisic acid.

[0019] Preferably, the molar ratio of the bio-based phenolic acid compound to dimethylaminopropylene glycol is (10-15): (20-40).

[0020] Preferably, the diisocyanate is selected from toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate.

[0021] Preferably, the catalyst is selected from dibutyltin dilaurate, stannous octoate or tin octoate.

[0022] Preferably, the solvent in step 2 is selected from one of N,N-dimethylformamide, acetone or tetrahydrofuran.

[0023] Preferably, the molar ratio of the bio-based polyol, diisocyanate and chain extender is (1-3): (3-10): (3-10).

[0024] Compared with the prior art solutions, the beneficial effects of the present invention are as follows:

[0025] The present invention provides an aqueous bio-based polyurethane sizing agent with anti-ultraviolet performance and a preparation method thereof. The sizing agent comprises 1-5 parts of bio-based polyurethane, 0.5-10 parts of neutralizer, and 90-98.5 parts of deionized water in parts by weight. The bio-based polyurethane in the present invention has the characteristics of low viscosity and terminal polyhydroxyl groups, which is conducive to forming a uniform coating containing a large number of polar functional groups on the surface of carbon fiber, so that the carbon fiber composite material exhibits better mechanical properties. At the same time, because the bio-based phenolic acid compound has good ultraviolet absorption performance, it can protect the bio-based polyurethane from being difficult to degrade under ultraviolet light, and can stably exist under long-term ultraviolet light irradiation environment. In addition, the use of low-cost, green and pollution-free bio-based raw materials also improves the environmental protection of the polyurethane sizing agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 These are the results of testing the interlaminar shear strength and bending strength of the composite material in this experimental example. Figure 2 This is the infrared spectrum of the bio-based polyurethane in the embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention first provides a water-based bio-based polyurethane sizing agent with UV resistance, which comprises, by weight:

[0028] 1-5 parts of bio-based polyurethane, 0.5-10 parts of neutralizer, 90-98.5 parts of deionized water;

[0029] The structural formula of the bio-based polyurethane is shown in Formula 1:

[0030]

[0031] In Formula 1, the value range of n is 20 to 80.

[0032] The present invention also provides a method for preparing a water-based bio-based polyurethane sizing agent with UV resistance, comprising the following steps:

[0033] Step 1: Preparation of bio-based polyols

[0034] First, the vegetable oil and diethanolamine were reacted under alkaline conditions with nitrogen for 4 hours, and the post-treated product was reacted with butanediol under acidic conditions with nitrogen at 180°C;

[0035] The vegetable oil is preferably selected from hemp flower oil, palm oil, algae oil and grass seed oil.

[0036] The alkaline condition is preferably selected from one of sodium hydroxide, sodium methoxide, sodium ethoxide, potassium ethoxide and sodium tert-butoxide.

[0037] The acidic condition is preferably selected from one of sulfuric acid, nitric acid, phosphoric acid and acetic acid.

[0038] Step 2: Preparation of bio-based polyurethane prepolymer

[0039] Bio-based polyol, diisocyanate, dimethylaminopropylene glycol and a catalyst are dissolved in a solvent, nitrogen is passed through, and the reaction is carried out at 70° C. to 80° C. for 2 to 4 hours to obtain a polyurethane prepolymer, and the solvent is removed by rotary evaporation and dried to obtain a bio-based polyurethane;

[0040] The catalyst is preferably selected from dibutyltin dilaurate, stannous octoate or tin octoate.

[0041] The solvent is preferably selected from one of N,N-dimethylformamide, acetone or tetrahydrofuran.

[0042] The diisocyanate is preferably selected from toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate.

[0043] The molar ratio of the bio-based polyol, diisocyanate, catalyst and chain extender is (1-3): (3-10): (0.3-1.5): (3-10).

[0044] Step 3: Preparation of waterborne bio-based polyurethane sizing agent with UV resistance

[0045] The bio-based polyurethane obtained in step 2 is dispersed in water under high-speed stirring, the stirring speed is preferably 200 rpm, and the neutralizing agent bio-based phenolic acid compound is slowly added dropwise for reaction, the reaction time is preferably 20-40 minutes, to obtain a water-based bio-based polyurethane sizing agent with anti-ultraviolet properties.

[0046] The bio-based phenolic acid compound is one of salicylic acid, gallic acid, ferulic acid or gentisic acid. The molar ratio of the bio-based phenolic acid compound to dimethylaminopropylene glycol is (10-15): (20-40).

[0047] The present invention is further described in detail below with reference to specific examples, in which the raw materials involved are all commercially available.

[0048] Comparative Example 1

[0049] Eight layers of nylon 6 film and seven layers of carbon fiber plain cloth were interwoven and stacked, and then heat-compressed to prepare a nylon 6 / carbon fiber composite material with a size of 100mm×100mm×0.3mm. The interlaminar shear strength and bending strength of the composite material were 56.28MPa and 567.22MPa, respectively, tested by a universal testing machine. Figure 1 shown.

[0050] Example 1

[0051] The preparation method of a bio-based polyurethane water-based sizing agent comprises the following steps:

[0052] (1) Weigh 33.92 g of diethanolamine and 0.37 g of sodium methoxide and place them in a 250 ml three-necked flask at 80 °C N 2 Stir and heat in an oil pan under atmosphere for 20 minutes, then add 87.9 g of algae oil, raise the temperature steadily to 120°C and stir for 4 hours. After cooling, the product is fully dissolved in ether and washed with saturated sodium chloride solution, the obtained ether layer is dried with anhydrous magnesium sulfate, and finally the ether is evaporated with a rotary vacuum evaporator to obtain polyether amide.

[0053] (2) Polyetheramide (0.05 mol) and dibutyl alcohol (0.035 mol) were dissolved in xylene, 2-5 ml of dilute sulfuric acid was added dropwise, and the mixture was heated under reflux at 180° C. until a theoretical amount of water was collected in the trap. After the reaction was completed, the solvent was evaporated in a vacuum rotary evaporator under reduced pressure to obtain a bio-based polyol.

[0054] (3) Weigh 2.70 g of isophorone diisocyanate, 5.17 g of bio-based polyol and 0.72 g of dimethylaminopropylene glycol into a three-necked flask equipped with a condenser and a mechanical stirrer, add acetone to mix them thoroughly, then add 2-3 ml of dibutyltin dilaurate to the mixture, and under nitrogen protection, heat to 78 ° C for 2 h to obtain a bio-based polyurethane prepolymer. Finally, use a rotary evaporator to remove the acetone in the polyurethane to obtain a bio-based polyurethane. The infrared spectrum of the obtained bio-based polyurethane is as follows: Figure 2 shown.

[0055] (4) Take 10 g of the bio-based polyurethane obtained in step (3), slowly add 4 ml of gentisic acid as a neutralizer, disperse it in water under high-speed stirring at 200 rpm, and react for 30 minutes to obtain a water-based bio-based polyurethane sizing agent with anti-ultraviolet properties.

[0056] The carbon fiber cloth was impregnated with the sizing agent prepared in Example 1, and the CF / PA6 composite material was manufactured by hot pressing technology. The CF / PA6 composite material was stacked by eight layers of PA6 film (120mm×100mm×0.3mm) and seven layers of CF fabric (120mm×100mm), and then pressed at 5MPa and 260°C for 30 minutes to obtain a composite material. The interlaminar shear test and bending strength test specimens were cut and tested by a universal testing machine to obtain an interlaminar shear strength of 56.28MPa and a bending strength of 567.22MPa. Figure 1 The results show that the mechanical properties are significantly improved compared with the unsized carbon fiber / nylon 6 composites.

[0057] Example 2

[0058] The preparation method of a bio-based polyurethane water-based sizing agent comprises the following steps:

[0059] (1) Weigh 33.92 g of diethanolamine and 0.37 g of sodium methoxide and place them in a 250 ml three-necked flask at 80 °C N 2 Stir and heat in an oil pan under atmosphere for 20 minutes, then add 87.9 g of algae oil, raise the temperature steadily to 120°C and stir for 4 hours. After cooling, the product is fully dissolved in ether and washed with saturated sodium chloride solution, the obtained ether layer is dried with anhydrous magnesium sulfate, and finally the ether is evaporated with a rotary vacuum evaporator to obtain polyether amide.

[0060] (2) Polyetheramide (0.05 mol) and dibutyl alcohol (0.035 mol) were dissolved in xylene, 2-5 ml of dilute sulfuric acid was added dropwise, and the mixture was heated under reflux at 180° C. until a theoretical amount of water was collected in the trap. After the reaction was completed, the solvent was evaporated in a vacuum rotary evaporator under reduced pressure to obtain a bio-based polyol.

[0061] (3) 1.35 g of isophorone diisocyanate, 2.59 g of bio-based polyol and 0.36 g of dimethylaminopropylene glycol were weighed and added into a three-necked flask equipped with a condenser and a mechanical stirrer, and acetone was added to mix them thoroughly. Then 2-3 ml of dibutyltin dilaurate was added to the mixture. Under nitrogen protection, the temperature was raised to 78 ° C for reaction for 2 h to obtain a bio-based polyurethane prepolymer. Finally, the acetone in the polyurethane was removed by a rotary evaporator to obtain a bio-based polyurethane. The infrared spectrum of the obtained bio-based polyurethane is as follows: Figure 2 shown.

[0062] (4) Take 7 g of the bio-based polyurethane obtained in step (3), slowly add 3 ml of gentisic acid as a neutralizer, disperse it in water under high-speed stirring at 200 rpm, and react for 30 minutes to obtain a water-based bio-based polyurethane sizing agent with anti-ultraviolet properties.

[0063] The carbon fiber cloth was impregnated with the sizing agent prepared in Example 2, and the CF / PA6 composite material was manufactured by hot pressing technology. The CF / PA6 composite material was stacked by eight layers of PA6 film (120mm×100mm×0.3mm) and seven layers of CF fabric (120mm×100mm), and then pressed at 5MPa and 260°C for 30 minutes to obtain a composite material. The interlaminar shear test and bending strength test specimens were cut and tested by a universal testing machine to obtain an interlaminar shear strength of 50.78MPa and a bending strength of 503.89MPa. Figure 1 The results show that the mechanical properties are significantly improved compared with the unsized carbon fiber / nylon 6 composites.

[0064] Example 3

[0065] The preparation method of a bio-based polyurethane water-based sizing agent comprises the following steps:

[0066] (1) Weigh 33.92 g of diethanolamine and 0.37 g of sodium methoxide and place them in a 250 ml three-necked flask at 80 °C N 2 Stir and heat in an oil pan under atmosphere for 20 minutes, then add 87.9 g of algae oil, raise the temperature steadily to 120°C and stir for 4 hours. After cooling, the product is fully dissolved in ether and washed with saturated sodium chloride solution, the obtained ether layer is dried with anhydrous magnesium sulfate, and finally the ether is evaporated with a rotary vacuum evaporator to obtain polyether amide.

[0067] (2) Polyetheramide (0.05 mol) and dibutyl alcohol (0.035 mol) were dissolved in xylene, 2-5 ml of dilute sulfuric acid was added dropwise, and the mixture was heated under reflux at 180° C. until a theoretical amount of water was collected in the trap. After the reaction was completed, the solvent was evaporated in a vacuum rotary evaporator under reduced pressure to obtain a bio-based polyol.

[0068] (3) Weigh 0.675 g of isophorone diisocyanate, 1.3 g of bio-based polyol and 0.18 g of dimethylaminopropylene glycol into a three-necked flask equipped with a condenser and a mechanical stirrer, add acetone to mix them thoroughly, then add 2-3 ml of dibutyltin dilaurate to the mixture, and under nitrogen protection, heat to 78 ° C for 2 h to obtain a bio-based polyurethane prepolymer. Finally, use a rotary evaporator to remove acetone from the polyurethane to obtain a bio-based polyurethane. The infrared spectrum of the obtained bio-based polyurethane is as follows: Figure 2 shown.

[0069] (4) Take 4 g of the bio-based polyurethane obtained in step (3), slowly add 2 ml of gentisic acid as a neutralizer, disperse it in water under high-speed stirring at 200 rpm, and react for 30 minutes to obtain a water-based bio-based polyurethane sizing agent with anti-ultraviolet properties.

[0070] The carbon fiber cloth was impregnated with the sizing agent prepared in Example 3, and the CF / PA6 composite material was manufactured by hot pressing technology. The CF / PA6 composite material is stacked by eight layers of PA6 film (120mm×100mm×0.3mm) and seven layers of CF fabric (120mm×100mm), and then pressed at 5MPa and 260°C for 30 minutes to obtain a composite material. The interlaminar shear test and bending strength test specimens were cut and tested by a universal testing machine to obtain an interlaminar shear strength of 54.25MPa and a bending strength of 542.74MPa. Figure 1 The results show that the mechanical properties are significantly improved compared with the unsized carbon fiber / nylon 6 composites.

[0071] Figure 2 The infrared spectrum of the high solid content bio-based polyurethane of the present invention is shown in FIG. 1 , wherein the characteristic absorption peak of the isocyanate group disappears completely, while the characteristic peak of the hydroxyl group appears at 3390 cm -1 At 1724 cm -1 The strong absorption peak at 1631 cm -1 The absorption peak at 1558 cm is the C=O bond in the urea structure. -1 The absorption peak at is the bending vibration peak of -NH, indicating that the -OH and NCO- groups have reacted; these results prove that the structure of the prepared bio-based polyurethane is as expected.

[0072] Figure 1 The results of testing interlaminar shear strength and flexural strength of composite materials prepared by sizing carbon fibers with the aqueous polyurethane sizing agent provided in Comparative Example 1 and Examples 1-3 of the present invention.

Claims

1. A water-based bio-based polyurethane sizing agent with UV resistance, characterized in that Calculated by weight, the composition comprises: 1-5 parts of bio-based polyurethane, 0.5-10 parts of neutralizer, and 90-98.5 parts of deionized water.

2. The water-based bio-based polyurethane sizing agent with UV resistance according to claim 1, characterized in that: The neutralizing agent is a bio-based carboxylic acid.

3. The method for preparing a water-based bio-based polyurethane sizing agent with UV resistance according to claim 1, characterized in that: The following steps are involved: Step 1: Bio-based polyols First, the vegetable oil and diethanolamine were reacted under alkaline conditions with nitrogen for 4 hours, and the post-treated product was reacted with butanediol under acidic conditions with nitrogen at 180°C; Step 2: Preparation of polyurethane prepolymer Bio-based polyol, diisocyanate, dimethylaminopropylene glycol and a catalyst are dissolved in a solvent, nitrogen is passed through, and the reaction is carried out at 70° C. to 80° C. for 2 to 4 hours to obtain a polyurethane prepolymer, and the solvent is removed by rotary evaporation and dried to obtain a bio-based polyurethane; Step 3: Preparation of waterborne bio-based polyurethane sizing agent with UV resistance The bio-based polyurethane obtained in step 2 is dispersed in water under high-speed stirring, and a neutralizing agent, bio-based phenolic acid, is added dropwise to react to obtain a water-based bio-based polyurethane sizing agent with anti-ultraviolet performance.

4. The method for preparing a water-based bio-based polyurethane sizing agent with UV resistance according to claim 3, characterized in that: The bio-based phenolic acid compound is one of salicylic acid, gallic acid, ferulic acid or gentisic acid.

5. The method for preparing a water-based bio-based polyurethane sizing agent with UV resistance according to claim 3, characterized in that: The molar ratio of the bio-based phenolic acid compound to dimethylaminopropylene glycol is (10-15): (20-40).

6. The method for preparing a water-based bio-based polyurethane sizing agent with UV resistance according to claim 3, characterized in that: The diisocyanate is preferably selected from toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate.

7. The method for preparing a water-based bio-based polyurethane sizing agent with UV resistance according to claim 3, characterized in that: The catalyst is selected from dibutyltin dilaurate, stannous octoate or tin octoate.

8. The method for preparing a water-based bio-based polyurethane sizing agent with UV resistance according to claim 3, characterized in that: The solvent in step 2 is selected from one of N,N-dimethylformamide, acetone or tetrahydrofuran.

9. The method for preparing a water-based hyperbranched polyurethane sizing agent with UV resistance according to claim 3, characterized in that: The molar ratio of the bio-based polyol, diisocyanate and chain extender is (1-3): (3-10): (3-10).

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