Lightweight soft polyurethane material for soft volleyball and preparation method of lightweight soft polyurethane material

Abstract

The invention discloses a light soft polyurethane material for a soft volleyball and a preparation method of the light soft polyurethane material, and relates to the technical field of polyurethane materials. The preparation method comprises the following steps: S1, adding polyether glycol, polyester glycol and isophorone diisocyanate into acetone under the protection of nitrogen, uniformly stirring and mixing, then adding dibutyltin dilaurate, and stirring and reacting at 75-85 DEG C for 1-3 hours; s2, adding a lignin-based chain extender into the reaction system, stirring and heating to 80-90 DEG C, stirring and reacting for 1-3 hours, then adding a diamine chain extender, and keeping the temperature and stirring and reacting for 30-60 minutes; s3, finally, activated calcium carbonate is added into a reaction system, stirring and mixing are conducted for 1-2 h, acetone is removed through rotary evaporation, and the light soft polyurethane material is obtained. The light soft polyurethane material has excellent mechanical properties, ultraviolet resistance and aging resistance, and light volleyballs obtained through processing are excellent in performance and better in applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane materials, in particular to a lightweight and soft polyurethane material for soft volleyball and a preparation method thereof. Background Art

[0002] Soft volleyball is a popular sport. However, the common soft volleyballs on the market have problems such as heavy weight, lack of flexibility and poor durability. This to a certain extent limits the performance of athletes during the sport and causes a certain amount of waste of resources.

[0003] In recent years, polyurethane materials have garnered widespread attention in the sports equipment field due to their excellent performance. Polyether polyurethane, in particular, offers excellent flexibility, making it a promising candidate for soft volleyballs. However, the excessive flexibility of polyether polyurethane makes the resulting soft volleyballs too soft, which can hinder the player's ability to strike with force and, to a certain extent, limit their performance. Furthermore, soft volleyball is an intense outdoor sport, and polyurethane materials are susceptible to UV radiation degradation.

[0004] Based on this, in order to solve the above problems, the present invention will prepare a lightweight polyurethane material for soft volleyball, which has good mechanical properties, UV resistance, and durability. The soft volleyball processed by it has excellent performance and better applicability. Summary of the Invention

[0005] The object of the present invention is to provide a lightweight and soft polyurethane material for soft volleyball and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for preparing a lightweight and flexible polyurethane material for a soft volleyball comprises the following steps:

[0008] S1: Under nitrogen protection, polyether diol, polyester diol, and isophorone diisocyanate are added to acetone, stirred and mixed evenly, and then dibutyltin dilaurate is added thereto, and stirred and reacted at 75-85°C for 1-3 hours;

[0009] S2: Then, add the lignin-based chain extender to the reaction system, stir and heat to 80-90°C, stir and react for 1-3 hours, then add the diamine chain extender, keep warm and stir and react for 0.5-1 hour;

[0010] S3: Finally, activated calcium carbonate is added to the reaction system, and the mixture is stirred for 1 to 2 hours. The acetone is removed by rotary evaporation to obtain a light and soft polyurethane material.

[0011] Furthermore, the lightweight and soft polyurethane material includes the following raw material components: by weight, 35-45 parts of polyether diol, 5-15 parts of polyester diol, 18-23 parts of isophorone diisocyanate, 0.1-0.3 parts of dibutyltin dilaurate, 4-8 parts of lignin-based chain extender, 1-3 parts of diamine chain extender, 5-10 parts of activated calcium carbonate, and 70 parts of acetone.

[0012] Furthermore, the mass ratio of the polyether diol to the polyester diol is (7-9):(1-3).

[0013] Furthermore, the polyether diol includes but is not limited to a combination of one or more of polytetramethylene ether diol, polyoxypropylene diol, polyether N-210, polyether N-220, and polyether N-240, and has an average molecular weight of 4000 to 6000.

[0014] Furthermore, the polyester diol includes but is not limited to a combination of one or more of polyethylene adipate, polyethylene glycol oxalate, polyethylene neopentyl glycol oxalate, and polycarbonate diol, and has an average molecular weight of 3000 to 5000.

[0015] Furthermore, the preparation method of the lignin-based chain extender is as follows: (1) adding lignin to dimethylformamide, stirring and dissolving to obtain a 0.02 g / mL lignin solution; adding 50-60 wt% hydrogen iodide solution to the lignin solution, stirring and heating to 155-165°C for 1-12 hours, and terminating the reaction; after it is naturally cooled to room temperature, adding sufficient n-hexane, stirring and mixing, then adding sufficient saturated sodium metabisulfite solution, continuing to stir and mix, standing for 0.5-1 hour, filtering and collecting the precipitate, washing and drying to obtain demethylated lignin; (2) adding demethylated lignin, glycidyl methacrylate, catalyst C-94, and 1-butyl-3-methylimidazole methanesulfonate to an appropriate amount of dimethylformamide, stirring and heating to 90-1 00℃ for 1-6h, then add 4-propyleneoxy-2-hydroxybenzophenone, keep warm and stir for 1-6h, terminate the reaction, wait for it to cool naturally to room temperature, add sufficient deionized water, stir and mix, let it stand for 0.5-1h, filter and collect the precipitate, wash and dry to obtain epoxy-containing lignin; (3) add epoxy-containing lignin and amino-terminated polydimethylsiloxane to a mixed solution of dimethylformamide and chloroform in a volume ratio of 1:1, stir and heat to 80-90℃ for 1-6h, then add 3-glycidyloxytrimethoxysilane, keep warm and stir for 1-6h, terminate the reaction, add sufficient deionized water, stir and mix, let it stand for 0.5-1h, filter and collect the precipitate, wash and dry to obtain a lignin-based chain extender.

[0016] Furthermore, the ratio of the lignin solution to the hydrogen iodide solution is 10:1.

[0017] Furthermore, the mass ratio of the demethylated lignin, glycidyl methacrylate, 4-propyleneoxy-2-hydroxybenzophenone, catalyst C-94, and 1-butyl-3-methylimidazolium methanesulfonate is 2:(0.5-0.7):(0.2-0.3):(0.02-0.025):(0.015-0.02).

[0018] Furthermore, the mass ratio of the epoxy-containing lignin, amino-terminated polydimethylsiloxane, and 3-glycidyloxytrimethoxysilane is 1:(0.1-0.2):(0.02-0.04).

[0019] Furthermore, the average molecular weight of the amino-terminated polydimethylsiloxane is 2000-3000.

[0020] Furthermore, the diamine chain extender includes but is not limited to a combination of one or more of ethylenediamine, propylenediamine, and isophoronediamine.

[0021] Furthermore, the activated calcium carbonate is obtained by activating light calcium carbonate;

[0022] The activation method is as follows: (1) 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol are mixed in a mass ratio of (0.04-0.06):1:4, and stirred for 0.5-1 hour to obtain a silane hydrolyzate; (2) light calcium carbonate is added to the silane hydrolyzate, stirred for 1-2 hours, filtered, and dried to obtain activated calcium carbonate.

[0023] Furthermore, the mass ratio of the 1,2-bis(trimethoxysilane)ethane and light calcium carbonate is (0.05-0.1):1.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) Polyether polyurethane contains abundant ether bonds, so it has good flexibility, which can show better flexibility. Moreover, polyether polyurethane is not easy to hydrolyze, and the ether bonds can also provide certain antistatic properties, making the volleyball easier to clean and maintain on a daily basis. In general, polyether polyurethane has better durability than polyester polyurethane. It is more suitable to use polyether polyurethane to make a lightweight and soft polyurethane material suitable for soft volleyball. However, the inventors also considered that if the flexibility of polyether polyurethane is too high, the volleyball prepared therefrom will not be easy to exert force when hitting. Therefore, the soft volleyball prepared using only polyether polyurethane cannot meet the requirements of practical applications. Polyester polyurethane has better mechanical properties and has higher strength and wear resistance than polyether polyurethane, which can just improve the performance of polyether polyurethane. Therefore, to obtain a polyurethane material with superior overall performance, the present invention adopts a compromise solution. During the polyurethane material preparation process, both a polyether diol and a portion of a polyester diol are introduced, and the two are reacted simultaneously with isophorone diisocyanate to produce a polyurethane material containing both polyether and polyester segments. This material not only meets the soft performance requirements of soft volleyballs but also improves their durability. It is not advisable to add too much polyester diol because the polyester segments have poor water resistance and are easily hydrolyzed, which reduces their durability during daily washing or contact with sweat. Therefore, a mass ratio of polyether diol to polyester diol of (7-9):(1-3) is more suitable.

[0026] (2) Relying solely on polyester segments to provide certain mechanical properties to polyurethane materials is not enough to meet the requirements of volleyball performance. Based on this, the present invention demethylates lignin to increase its phenolic hydroxyl content, providing more reaction sites for subsequent chemical modification, and then reacts the phenolic hydroxyl groups on the lignin with the double bonds of glycidyl methacrylate and 4-propyleneoxy-2-hydroxybenzophenone in sequence to obtain epoxy-containing lignin, and then reacts the epoxy-containing lignin with amino-terminated polydimethylsiloxane, and then caps it with 3-glycidyloxytrimethylsilane to obtain a lignin chain extender. The lignin chain extender is obtained by modifying lignin, and lignin has a certain rigidity. When introduced into the polyurethane chain end, it can improve the strength and wear resistance of the polyurethane material. In addition, due to the demethylation of lignin, the phenolic hydroxyl content on the lignin-based chain extender is relatively high. At the same time, combined with the benzophenone structure introduced into the lignin-based chain extender, the lignin chain extender has relatively excellent anti-ultraviolet oxidation performance. Furthermore, polydimethylsiloxane segments and silane chain ends are introduced into the lignin chain extender. Among them, the role of the polydimethylsiloxane segment is: first, it can cooperate with the benzophenone structure and the phenolic hydroxyl group on the lignin to play an anti-ultraviolet oxidation role, thereby improving the anti-aging performance of the polyurethane material; its dimethylsiloxane segment has a certain lubricity, which can better combine with the rigidity of lignin and improve the wear resistance of the polyurethane; its trimethylsiloxane chain end has a certain hydrophobicity, which can delay the hydrolysis of the polyester segment in the polyurethane, thereby improving the durability of the polyurethane material; The role of the alkyl chain segment is: it has a blocking effect to prevent the epoxy-containing lignin and amino-terminated polydimethylsiloxane from agglomerating; secondly, after the volleyball is prepared, although the polydimethylsiloxane chain segment is hydrophobic, it is inevitable that some water will invade as time goes by. At this time, the silane chain end will hydrolyze. On the one hand, it can form a delayed cross-linking network with the subsequently added filler, thereby achieving a self-reinforcement effect. On the other hand, the silane chain end has a higher hydrolysis ability, which can avoid the hydrolysis of the polyester chain segment. All these factors enable the volleyball to maintain good performance for a long time and have excellent anti-aging properties.

[0027] (3) The present invention also adds a diamine chain extender, the amino group contained in the diamine chain extender can form a polyurea structure with the isocyanate group, which can further enhance the relevant mechanical properties of the polyurethane material and improve the structural stability of the polyurethane material.

[0028] (4) In the present invention, 1,2-bis(trimethoxysilane)ethane is used to activate light calcium carbonate. 1,2-bis(trimethoxysilane)ethane contains multiple hydroxyl groups after hydrolysis. Using it to treat light calcium carbonate can increase the number of hydroxyl groups on the light calcium carbonate, so that it can better combine with the hydrolyzed silane segments on the lignin chain extender in the later stage, forming a delayed cross-linking network, thereby enhancing the performance of the volleyball and delaying the aging of the volleyball. Furthermore, the hydroxyl groups can also form hydrogen bonds with the carbamate groups in the polyurethane chain ends, preventing phase separation between the light calcium carbonate and the polyurethane material, thereby enhancing the mechanical properties and UV resistance of the polyurethane material.

[0029] In summary, the present invention strengthens the polyurethane material by adjusting the amount of polyether diol and polyester diol, and introducing lignin chain extender, diamine chain extender, and activated light calcium carbonate, thereby comprehensively obtaining a lightweight and soft polyurethane material with excellent mechanical properties, UV resistance, and anti-aging properties. The lightweight volleyball prepared therefrom has excellent performance and better applicability. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] It should be noted that the following parts are calculated by weight, and the purchasers of all raw materials involved in the present invention include, without any special restrictions, the following examples:

[0032] In the following examples, polytetramethylene glycol, average molecular weight 5000; polyethylene adipate, average molecular weight 4000; lignin, purity 99%, average molecular weight 18000; catalyst C-94, produced by Acordis, Germany; amino-terminated polydimethylsiloxane, average molecular weight 2500, product number 481688; all were purchased from Merck Reagent Co., Ltd.

[0033] Glycidyl methacrylate, purity 99.5%; 3-glycidyloxytrimethoxysilane, purity 99.5%; 1,2-bis(trimethoxysilane)ethane, purity 99.5%; ethylenediamine, purity 99%; all purchased from Hubei Jusheng Technology Co., Ltd.

[0034] 1-Butyl-3-methylimidazolium methanesulfonate, purity 99%, purchased from Shanghai Dingmiao Chemical Technology Co., Ltd.;

[0035] Light calcium carbonate, purity 99%, product number CG112, density 0.5-1.5g / cm 3 , purchased from Shandong Zhengxing New Materials Co., Ltd.; other raw materials were purchased from the market, and the following parts are by weight.

[0036] Example 1: A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0037] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 9 hours to terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) Add 8 parts of demethylated lignin, 2.4 parts of glycidyl methacrylate, 0.09 parts of catalyst C-94, 0.07 parts of 1-butyl-3-methylimidazole methanesulfonate to 20 parts of dimethylformamide (3) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. After the mixture was cooled to room temperature naturally, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (4) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0038] Preliminary preparation 2: Preparation of activated calcium carbonate: (1) Mix 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol in a mass ratio of 0.05:1:4, and stir for 45 minutes to obtain a silane hydrolyzate; (2) Add light calcium carbonate to the silane hydrolyzate, stir for 1.5 hours, filter, and dry to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate is 0.075:1;

[0039] S1: Under nitrogen protection, 40 parts of polytetramethylene ether glycol, 10 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0040] S2: Then, 6 parts of lignin-based chain extender were added to the reaction system, heated to 85°C with stirring, and stirred for 2 hours. Then, 2 parts of ethylenediamine were added, and the mixture was stirred and stirred for 60 minutes.

[0041] S3: Finally, 7.5 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0042] Example 2: A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0043] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 1 hour to terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) Add 8 parts of demethylated lignin, 2 parts of glycidyl methacrylate, 0.08 parts of catalyst C-94, 0.06 parts of 1-butyl-3-methylimidazole methanesulfonate to 20 parts of dimethylformamide (3) 8 parts of epoxy-containing lignin and 0.8 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.16 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. After the mixture was cooled to room temperature naturally, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (4) 8 parts of epoxy-containing lignin and 0.8 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.16 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0044] Preliminary preparation 2: Preparation of activated calcium carbonate: (1) 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol were mixed in a mass ratio of 0.05:1:4, and stirred for 45 minutes to obtain a silane hydrolyzate; (2) Light calcium carbonate was added to the silane hydrolyzate, stirred for 1.5 hours, filtered, and dried to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate was 0.05:1;

[0045] S1: Under nitrogen protection, 40 parts of polytetramethylene ether glycol, 10 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0046] S2: Then, 6 parts of lignin-based chain extender were added to the reaction system, heated to 85°C with stirring, and stirred for 2 hours. Then, 2 parts of ethylenediamine were added, and the mixture was stirred and stirred for 60 minutes.

[0047] S3: Finally, 7.5 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0048] Example 3: A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0049] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 12 hours to terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) Add 8 parts of demethylated lignin, 2.8 parts of glycidyl methacrylate, 0.1 parts of catalyst C-94, 0.08 parts of 1-butyl-3-methylimidazole methanesulfonate to 20 parts of dimethylformamide (3) 8 parts of epoxy-containing lignin and 1.6 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.32 parts of 3-glycidyloxytrimethoxysilane were added, and the mixture was stirred and reacted for 4 hours, and the reaction was terminated. After the mixture was naturally cooled to room temperature, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (4) 8 parts of epoxy-containing lignin and 1.6 parts of amino-terminated polydimethylsiloxane were added to a mixed solution obtained by mixing 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.32 parts of 3-glycidyloxytrimethoxysilane were added, and the mixture was stirred and reacted for 4 hours, and the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0050] Preliminary preparation 2: Preparation of activated calcium carbonate: (1) Mix 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol in a mass ratio of 0.05:1:4, and stir for 45 minutes to obtain a silane hydrolyzate; (2) Add light calcium carbonate to the silane hydrolyzate, stir for 1.5 hours, filter, and dry to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate is 0.1:1;

[0051] S1: Under nitrogen protection, 40 parts of polytetramethylene ether glycol, 10 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0052] S2: Then, 6 parts of lignin-based chain extender were added to the reaction system, heated to 85°C with stirring, and stirred for 2 hours. Then, 2 parts of ethylenediamine were added, and the mixture was stirred and stirred for 60 minutes.

[0053] S3: Finally, 7.5 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0054] Example 4: A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0055] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 9 hours to terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) Add 8 parts of demethylated lignin, 2.4 parts of glycidyl methacrylate, 0.09 parts of catalyst C-94, 0.07 parts of 1-butyl-3-methylimidazole methanesulfonate to 20 parts of dimethylformamide (3) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. After the mixture was cooled to room temperature naturally, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (4) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0056] Preliminary preparation 2: Preparation of activated calcium carbonate: (1) Mix 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol in a mass ratio of 0.05:1:4, and stir for 45 minutes to obtain a silane hydrolyzate; (2) Add light calcium carbonate to the silane hydrolyzate, stir for 1.5 hours, filter, and dry to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate is 0.075:1;

[0057] S1: Under nitrogen protection, 35 parts of polytetramethylene ether glycol, 15 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0058] S2: Then, 4 parts of lignin-based chain extender were added to the reaction system, heated to 85°C with stirring, and reacted with stirring for 2 hours. Then, 1 part of ethylenediamine was added, and the mixture was stirred and reacted for 60 minutes;

[0059] S3: Finally, 5 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0060] Example 5: A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0061] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 9 hours to terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) Add 8 parts of demethylated lignin, 2.4 parts of glycidyl methacrylate, 0.09 parts of catalyst C-94, 0.07 parts of 1-butyl-3-methylimidazole methanesulfonate to 20 parts of dimethylformamide (3) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. After the mixture was cooled to room temperature naturally, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (4) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0062] Preliminary preparation 2: Preparation of activated calcium carbonate: (1) Mix 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol in a mass ratio of 0.05:1:4, and stir for 45 minutes to obtain a silane hydrolyzate; (2) Add light calcium carbonate to the silane hydrolyzate, stir for 1.5 hours, filter, and dry to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate is 0.075:1;

[0063] S1: Under nitrogen protection, 45 parts of polytetramethylene ether glycol, 5 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, stirred and mixed uniformly, and then 0.2 parts of dibutyltin dilaurate were added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0064] S2: Then, 8 parts of lignin-based chain extender were added to the reaction system, heated to 85°C with stirring, and reacted with stirring for 2 hours. Then, 3 parts of ethylenediamine were added, and the mixture was stirred and reacted for 60 minutes;

[0065] S3: Finally, 10 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0066] The following comparative experiments were conducted based on Example 1, and comparative examples 1 to 5 were set as follows:

[0067] Comparative Example 1: Comparative Example 1 is based on Example 1, with the following adjustments: no polyester diol is added, and other processes remain unchanged, specifically:

[0068] A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0069] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 9 hours to terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) Add 8 parts of demethylated lignin, 2.4 parts of glycidyl methacrylate, 0.09 parts of catalyst C-94, 0.07 parts of 1-butyl-3-methylimidazole methanesulfonate to 20 parts of dimethylformamide (3) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. After the mixture was cooled to room temperature naturally, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (4) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0070] Preliminary preparation 2: Preparation of activated calcium carbonate: (1) Mix 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol in a mass ratio of 0.05:1:4, and stir for 45 minutes to obtain a silane hydrolyzate; (2) Add light calcium carbonate to the silane hydrolyzate, stir for 1.5 hours, filter, and dry to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate is 0.075:1;

[0071] S1: Under nitrogen protection, 50 parts of polytetramethylene glycol and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0072] S2: Then, 6 parts of lignin-based chain extender were added to the reaction system, heated to 85°C with stirring, and stirred for 2 hours. Then, 2 parts of ethylenediamine were added, and the mixture was stirred and stirred for 60 minutes.

[0073] S3: Finally, 7.5 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0074] Comparative Example 2: Comparative Example 2 is based on Example 1, with the following adjustments: no lignin-based chain extender is added, and other processes remain unchanged, specifically:

[0075] A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0076] Preliminary preparation 1: Preparation of activated calcium carbonate: (1) Mix 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol in a mass ratio of 0.05:1:4, and stir for 45 minutes to obtain a silane hydrolyzate; (2) Add light calcium carbonate to the silane hydrolyzate, stir for 1.5 hours, filter, and dry to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate is 0.075:1;

[0077] S1: Under nitrogen protection, 40 parts of polytetramethylene ether glycol, 10 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0078] S2: Then, 8 parts of ethylenediamine were added to the reaction system, heated to 85°C with stirring, and reacted with stirring for 2 hours;

[0079] S3: Finally, 7.5 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0080] Comparative Example 3: Comparative Example 3 is based on Example 1, with the following adjustments: 4-propyleneoxy-2-hydroxybenzophenone is not added during the preparation of epoxy-containing lignin, and other processes remain unchanged, specifically:

[0081] A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0082] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 9 hours, and terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) 8 parts of demethylated lignin, 3.4 parts of glycidyl methacrylate, 0.09 parts of catalyst C-94, 0.07 parts of 1-butyl-3-methyl (3) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, and the mixture was stirred and reacted for 4 hours, and then the reaction was terminated. After the mixture was naturally cooled to room temperature, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (4) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, and the mixture was stirred and reacted for 4 hours, and then the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0083] Preliminary preparation 2: Preparation of activated calcium carbonate: (1) Mix 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol in a mass ratio of 0.05:1:4, and stir for 45 minutes to obtain a silane hydrolyzate; (2) Add light calcium carbonate to the silane hydrolyzate, stir for 1.5 hours, filter, and dry to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate is 0.075:1;

[0084] S1: Under nitrogen protection, 40 parts of polytetramethylene ether glycol, 10 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0085] S2: Then, 6 parts of lignin-based chain extender were added to the reaction system, heated to 85°C with stirring, and stirred for 2 hours. Then, 2 parts of ethylenediamine were added, and the mixture was stirred and stirred for 60 minutes.

[0086] S3: Finally, 7.5 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0087] Comparative Example 4: Comparative Example 4 is based on Example 1, with the following modifications: amino-terminated polydimethylsiloxane and 3-glycidyloxytrimethoxysilane are not added, and 3-aminopropyltriethoxysilane is used instead. Other processes remain unchanged, specifically:

[0088] A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0089] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 9 hours, and terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) 8 parts of demethylated lignin, 2.4 parts of glycidyl methacrylate, 0.09 parts of catalyst C-94, 0.07 parts of 1-butyl-3- Methylimidazole methanesulfonate was added to 20 parts of dimethylformamide, stirred and heated to 95°C for reaction for 4 hours, and then 1 part of 4-propyleneoxy-2-hydroxybenzophenone was added, and the mixture was stirred and reacted for 4 hours. The reaction was terminated, and after it was naturally cooled to room temperature, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (3) 8 parts of epoxy-containing lignin and 1.44 parts of 3-aminopropyltriethoxysilane were added to a mixed solution obtained by mixing 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for reaction for 4 hours, and the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0090] Preliminary preparation 2: Preparation of activated calcium carbonate: (1) Mix 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol in a mass ratio of 0.05:1:4, and stir for 45 minutes to obtain a silane hydrolyzate; (2) Add light calcium carbonate to the silane hydrolyzate, stir for 1.5 hours, filter, and dry to obtain activated calcium carbonate; wherein the mass ratio of 1,2-bis(trimethoxysilane)ethane to light calcium carbonate is 0.075:1;

[0091] S1: Under nitrogen protection, 40 parts of polytetramethylene ether glycol, 10 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0092] S2: Then, 6 parts of lignin-based chain extender were added to the reaction system, heated to 85°C with stirring, and stirred for 2 hours. Then, 2 parts of ethylenediamine were added, and the mixture was stirred and stirred for 60 minutes.

[0093] S3: Finally, 7.5 parts of activated calcium carbonate were added to the reaction system, stirred and mixed for 2 hours, and acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0094] Comparative Example 5: Comparative Example 5 is based on Example 1, with the following adjustments: no activated calcium carbonate is added, and other processes remain unchanged, specifically:

[0095] A method for preparing a lightweight and soft polyurethane material for soft volleyball:

[0096] Preliminary preparation 1: Preparation of lignin-based chain extender: (1) Add lignin to dimethylformamide, stir and dissolve to obtain 0.02 g / mL lignin solution; add 55 wt% hydrogen iodide solution to the lignin solution, stir and heat to 160 ° C for 9 hours to terminate the reaction; after it is naturally cooled to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let it stand for 1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin, wherein the volume ratio of lignin solution to hydrogen iodide solution is 10:1; (2) Add 8 parts of demethylated lignin, 2.4 parts of glycidyl methacrylate, 0.09 parts of catalyst C-94, 0.07 parts of 1-butyl-3-methylimidazole methanesulfonate to 20 parts of dimethylformamide (3) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. After the mixture was cooled to room temperature naturally, sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain epoxy-containing lignin; (4) 8 parts of epoxy-containing lignin and 1.2 parts of amino-terminated polydimethylsiloxane were added to a mixed solution of 20 parts of dimethylformamide and chloroform in a volume ratio of 1:1, stirred and heated to 85°C for 4 hours, and then 0.24 parts of 3-glycidyloxytrimethoxysilane were added, heated and stirred for 4 hours, and then the reaction was terminated. Sufficient deionized water was added, stirred and mixed, and the mixture was allowed to stand for 1 hour. The precipitate was collected by filtration, washed, and dried to obtain a lignin-based chain extender;

[0097] S1: Under nitrogen protection, 40 parts of polytetramethylene ether glycol, 10 parts of polyethylene adipate, and 21 parts of isophorone diisocyanate were added to 70 parts of acetone, and the mixture was stirred and mixed uniformly. Then, 0.2 parts of dibutyltin dilaurate was added thereto, and the mixture was stirred and reacted at 80°C for 2 hours;

[0098] S2: Then, 6 parts of lignin-based chain extender were added to the reaction system, the temperature was raised to 85°C with stirring, and the reaction was stirred for 2 hours. Then, 2 parts of ethylenediamine were added, and the temperature was kept stirring for 60 minutes. After the reaction was terminated, the acetone was removed by rotary evaporation to obtain a lightweight and soft polyurethane material.

[0099] Performance testing: Under molding conditions of 180°C and 15 MPa, the lightweight, flexible polyurethane materials prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were processed into 20 cm × 2 cm × 2 cm test specimens. The specimens were then subjected to tensile performance tests, UV resistance tests, water vapor aging tests, and wear resistance tests. The specific testing methods are as follows:

[0100] (1) Tensile strength test: Use a universal testing machine to test the tensile strength and elongation at break of the test specimens;

[0101] (2) Anti-ultraviolet performance test: At a distance of 30 cm from the test specimen, use ultraviolet light with a wavelength of 365 nm and a power of 20 W / cm 2 The light intensity was irradiated with UV light for 120 hours, and then the tensile strength was tested;

[0102] (3) Water vapor aging performance test: The test specimens were placed in an environment of 20±2°C and 95% humidity for 360 hours, and then subjected to a tensile strength test;

[0103] (4) Wear resistance test: A friction and wear tester was used to test the strips at a speed of 200 r / min under a load of 30 N for 1 h, and the mass difference between the strips before and after the test was calculated.

[0104] The specific test results are shown in Table 1 below:

[0105] Table 1

[0106]

[0107] Result analysis: From the data in Table 1 above, it can be seen that the present invention achieves a lightweight and soft polyurethane material with excellent mechanical properties, anti-ultraviolet aging properties, anti-water vapor aging properties, and wear resistance by: ① adjusting the usage ratio of polyether diol and polyester diol; ② demethylating lignin, introducing benzophenone structure, polydimethylsiloxane chain segments, and silane chain ends; ③ introducing light calcium carbonate and activating the light calcium carbonate.

[0108] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a lightweight and flexible polyurethane material for soft volleyball, characterized by: The following steps are involved: S1: Under nitrogen protection, polyether diol, polyester diol, and isophorone diisocyanate are added to acetone, stirred and mixed evenly, and then dibutyltin dilaurate is added thereto, and stirred and reacted at 75-85°C for 1-3 hours; S2: Then, add the lignin-based chain extender to the reaction system, stir and heat to 80-90°C, stir and react for 1-3 hours, then add the diamine chain extender, keep warm and stir and react for 0.5-1 hour; S3: Finally, activated calcium carbonate is added to the reaction system, stirred and mixed for 1 to 2 hours, and acetone is removed by rotary evaporation to obtain a lightweight and soft polyurethane material; The lightweight and flexible polyurethane material comprises the following raw material components: by weight, 35-45 parts of polyether diol, 5-15 parts of polyester diol, 18-23 parts of isophorone diisocyanate, 0.1-0.3 parts of dibutyltin dilaurate, 4-8 parts of lignin-based chain extender, 1-3 parts of diamine chain extender, 5-10 parts of activated calcium carbonate, and 70 parts of acetone; The mass ratio of the polyether diol to the polyester diol is (7-9):(1-3); The activated calcium carbonate is obtained by activating light calcium carbonate.

2. The method for preparing a lightweight and flexible polyurethane material for soft volleyball according to claim 1, characterized in that: The polyether diol includes one or more of polytetramethylene ether diol, polyoxypropylene diol, polyether N-210, polyether N-220, and polyether N-240, and has an average molecular weight of 4000 to 6000.

3. The method for preparing a lightweight and flexible polyurethane material for soft volleyball according to claim 1, characterized in that: The polyester diol comprises a combination of one or more of polyethylene adipate, polyethylene oxalate, polyethylene neopentyl oxalate, and polycarbonate diol, and has an average molecular weight of 3,000 to 5,000.

4. The method for preparing a lightweight and flexible polyurethane material for soft volleyball according to claim 1, characterized in that: The preparation method of the lignin-based chain extender is: (1) Add lignin to dimethylformamide and stir to dissolve to obtain a 0.02 g / mL lignin solution; add 50-60 wt% hydrogen iodide solution to the lignin solution, stir and heat to 155-165°C for 1-12 hours, and terminate the reaction; after cooling naturally to room temperature, add sufficient n-hexane, stir and mix, then add sufficient saturated sodium metabisulfite solution, continue to stir and mix, let stand for 0.5-1 hour, filter and collect the precipitate, wash and dry to obtain demethylated lignin; (2) Demethylated lignin, glycidyl methacrylate, catalyst C-94, and 1-butyl-3-methylimidazole methanesulfonate are added to an appropriate amount of dimethylformamide, stirred and heated to 90-100°C for reaction for 1-6 hours, and then 4-propyleneoxy-2-hydroxybenzophenone is added. The mixture is stirred and reacted for 1-6 hours. The reaction is terminated, and after naturally cooling to room temperature, sufficient deionized water is added, stirred and mixed, and allowed to stand for 0.5-1 hour. The precipitate is collected by filtration, washed, and dried to obtain epoxy-containing lignin; (3) Add epoxy-containing lignin and amino-terminated polydimethylsiloxane to a mixed solution of dimethylformamide and chloroform in a volume ratio of 1:1, stir and heat to 80-90°C for reaction for 1-6 hours, then add 3-glycidyloxytrimethoxysilane, keep warm and stir for reaction for 1-6 hours, terminate the reaction, add sufficient deionized water, stir and mix, let stand for 0.5-1 hour, filter and collect the precipitate, wash and dry to obtain a lignin-based chain extender.

5. The method for preparing a lightweight and flexible polyurethane material for soft volleyball according to claim 4, characterized in that: The ratio of the lignin solution to the hydrogen iodide solution is 10:1; The mass ratio of the demethylated lignin, glycidyl methacrylate, 4-propyleneoxy-2-hydroxybenzophenone, catalyst C-94, and 1-butyl-3-methylimidazolium methanesulfonate is 2:(0.5-0.7):(0.2-0.3):(0.02-0.025):(0.015-0.02); The mass ratio of the epoxy-containing lignin, amino-terminated polydimethylsiloxane, and 3-glycidyloxytrimethoxysilane is 1:(0.1-0.2):(0.02-0.04); The average molecular weight of the amino-terminated polydimethylsiloxane is 2000-3000.

6. The method for preparing a lightweight and flexible polyurethane material for soft volleyball according to claim 1, characterized in that: The diamine chain extender includes one or more of ethylenediamine, propylenediamine, and isophoronediamine.

7. The method for preparing a lightweight and flexible polyurethane material for soft volleyball according to claim 1, characterized in that: The activation method of the activated calcium carbonate is: (1) 1,2-bis(trimethoxysilane)ethane, deionized water, and anhydrous ethanol were mixed in a mass ratio of (0.04-0.06):1:4, and stirred for 0.5-1 h to obtain a silane hydrolyzate; (2) Adding light calcium carbonate to the silane hydrolyzate, stirring and mixing for 1 to 2 hours, filtering and drying to obtain activated calcium carbonate.

8. The method for preparing a lightweight and flexible polyurethane material for soft volleyball according to claim 7, characterized in that: The mass ratio of the 1,2-bis(trimethoxysilane)ethane and light calcium carbonate is (0.05-0.1):

1.

9. A lightweight and soft polyurethane material prepared by the method for preparing a lightweight and soft polyurethane material for soft volleyball according to any one of claims 1 to 8.

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