A transparent bio-based nylon resin and its preparation method

Abstract

This invention discloses a transparent bio-based nylon resin and its preparation method. The preparation method includes: reacting bio-based pentanediamine with terephthalic acid and isophthalic acid to form a salt, obtaining a mixed salt of nylon 5T and 5I; subjecting the nylon 5T and 5I mixed salt to a prepolymerization reaction under the action of a catalyst to obtain a prepolymer of nylon 5T and 5I; adding the obtained prepolymer and a nucleating agent to a tubular reactor for a final polymerization reaction to obtain a transparent nylon resin; pressurizing the obtained transparent nylon resin into an extruder, adding a tackifier and a first compatibilizer for solid-phase tackification, then drawing the resin into strips and feeding them into a pelletizer for pelletizing; and drying the pellets to obtain transparent bio-based nylon resin chips. This invention solves the problems of inaccurate control of polymerization temperature, poor stability of transparent nylon, easy oxidation and yellowing, and easy clogging of reaction equipment by polymer as molecular weight increases.

Description

Technical Field

[0001] This invention relates to the field of nylon preparation, specifically to a transparent bio-based nylon resin and its preparation method. Background Technology

[0002] Currently, the raw materials for nylon 6 and nylon 66 products widely used in industry are mainly derived from the reprocessing of petroleum refining byproducts, resulting in a high dependence on petroleum and environmental pollution problems during the manufacturing process. The synthesis of novel, green, and sustainable nylons has become a research hotspot in recent years. Utilizing inexpensive and renewable biomass resources as raw materials and employing bioengineering methods to synthesize the raw materials needed for nylon to prepare bio-based nylon products is one of the future development trends for nylon.

[0003] Bio-based nylon materials refer to materials produced from renewable biomass resources, such as glucose, cellulose, and vegetable oils (including castor oil, oleic acid, and linoleic acid), through bioengineering methods. These raw materials are typically diacids, diamines, or lactams. Common bio-based nylon materials include nylon 56, nylon 510, nylon 5T, nylon 11, nylon 1010, nylon 610, nylon 410, and nylon 1012. Bio-based nylon has numerous applications in clothing fibers, natural gas pipelines, medical protective goggles, metal protective coatings, high-end fire-resistant oil-gas separators and crankshaft end caps, food packaging, automotive fuel lines, LED packaging components, and sporting goods.

[0004] Transparent nylon, a type of specialty nylon, is a thermoplastic nylon with a microcrystalline or amorphous structure. At a thickness of 2mm, its light transmittance exceeds 90%, and it exhibits superior abrasion resistance, chemical resistance, flexibility, and low density. Furthermore, it significantly outperforms PC and PMMA in environmental stress cracking resistance. Currently, the annual consumption of transparent nylon is substantial, but production capacity is very low. Traditional raw materials for nylon 6 and nylon 66 are obtained through petroleum cracking. The raw material for synthesizing transparent bio-based nylons, such as nylon 5T, is 1,5-pentanediamine, which can be converted from lysine through bioengineering, significantly reducing dependence on petroleum. PA5T possesses advantages such as high tensile strength and heat resistance, making it a viable alternative to nylon 6 in the automotive and electrical / electronic industries. Nylon 5T's excellent weldability, high-temperature rigidity, chemical resistance, low water absorption, excellent dimensional stability, excellent flowability, and resistance to burrs during molding make it a promising alternative to traditional nylon 6 and nylon 66 in the electronics and automotive industries. If 40% of nylon 66 is replaced by bio-based nylon in the future, its market size will reach 1.4 million tons per year, indicating a broad market prospect. Therefore, research and development of transparent bio-based nylon product preparation technology is of great significance.

[0005] CN202211398042.6 discloses a bio-based copolymer transparent nylon and its preparation method. The preparation method includes: 1) mixing aliphatic diamine, aromatic diacid, isosorbide, aromatic acid, catalyst and deionized water; 2) stirring and heating the mixture under a protective atmosphere, controlling the reaction temperature and pressure, and reacting for 2-3 hours; 3) heating and pressurizing the mixture, controlling the reaction temperature and pressure, and reacting for 3-4 hours; 4) depressurizing the mixture to a reaction pressure of 0.2-0.5 MPa, heating it to a reaction temperature of 310-340°C, and then evacuating it under vacuum for 1-3 hours; finally, pressurizing the mixture to discharge it, thus obtaining the bio-based copolymer transparent nylon.

[0006] CN202111351444.6 discloses a nylon comprising a bio-based nylon 5X polymer, wherein the raw materials for the bio-based nylon 5X polymer include nylon 5X salt, a phenolic antioxidant, and a hindered amine light stabilizer. The polymerization method employs a concentrated polyamide 5X salt solution, and the polymerization process is divided into two steps: pre-polymerization and post-polymerization. Flash evaporation is performed between the two polymerization steps, and finally, the nylon 5X resin is sliced ​​and processed at high temperature.

[0007] CN202211335848.0 discloses the application of low-melting-point copolymer nylon 56 / 66 in transparent films. The transparency of the nylon 56 / 66 copolymer is improved by increasing the content of PA56 segments. The preparation method is as follows: 1) In an inert atmosphere, nylon 56 salt and nylon 56 salt crystals or their aqueous solution are directly mixed to obtain an aqueous solution of nylon 56 / 66 salt; 2) The aqueous solution of nylon 56 / 66 salt is subjected to melt polycondensation to obtain copolymer nylon 56 / 66.

[0008] Although the above-mentioned existing technologies provide a method for preparing transparent bio-based nylon, the following problems still exist: (1) Nylon polymerization needs to be carried out at high temperature. The reaction temperature of the reactor polymerization cannot be precisely controlled, which will lead to uneven molecular weight distribution of nylon products and generate more energy consumption; (2) Although the synthesized transparent bio-based nylon has high transparency, it has poor stability. It is easy to oxidize and turn yellow after being stored for a long time, which reduces its transparency and limits its application; (3) Solid-phase thickening or vacuuming to increase molecular weight in the reaction equipment is very easy to clog the reaction equipment and the reaction process is unsafe and has high energy consumption. Summary of the Invention

[0009] The purpose of this invention is to provide a transparent bio-based nylon resin and its preparation method. This addresses the problems in existing technologies, such as the inability to precisely control the polymerization temperature, the poor stability of transparent nylon, its susceptibility to oxidation and yellowing, and the tendency for the polymer to clog reaction equipment as the molecular weight increases.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] This invention provides a method for preparing a transparent bio-based nylon resin, the method comprising the following steps:

[0012] Bio-based pentanediamine reacts with terephthalic acid and isophthalic acid to form a salt, yielding a mixed salt of nylon 5T and 5I.

[0013] The nylon 5T and 5I mixed salt undergoes a prepolymerization reaction under the action of a catalyst to obtain nylon 5T and 5I prepolymers;

[0014] The obtained prepolymer and nucleating agent were added to a tubular reactor for final polymerization to obtain transparent nylon resin;

[0015] The obtained transparent nylon resin was pressurized and fed into an extruder, and a tackifier and a first compatibilizer were added for solid-phase tackification. Then, it was drawn into strips and fed into a pelletizer for pelletizing. After drying, transparent bio-based nylon resin chips were obtained.

[0016] In some embodiments of the present invention, the molar ratio of the bio-based pentanediamine to terephthalic acid and isophthalic acid is 1:(1 to 1.2).

[0017] In some embodiments of the present invention, the molar ratio of terephthalic acid to isophthalic acid is 1:(2-4).

[0018] In some embodiments of the present invention, the salt formation reaction is carried out in water, and the resulting nylon 5T and 5I mixed salt solution and catalyst are added to a reaction vessel to carry out the prepolymerization reaction to obtain nylon 5T and 5I prepolymers.

[0019] In some embodiments of the present invention, the salt-forming reaction is carried out at a temperature of 60–90°C and for a time of 0.5–2 h.

[0020] In some embodiments of the present invention, the mass ratio of the nylon 5T, 5I mixed salt to water is 1:(0.3-0.8).

[0021] In some embodiments of the present invention, the catalyst is a combination of anhydrous acetic acid and sodium hypochlorite in a molar ratio of 1:1.

[0022] In some embodiments of the present invention, the amount of catalyst added is 0.3% to 2% of the mass of the nylon 5T and 5I mixed salt solution.

[0023] In some embodiments of the present invention, the reaction temperature of the prepolymerization reaction is 120–160°C, the reaction pressure is 1.5–4 MPa, and the reaction time is 0.5–2 h.

[0024] In some embodiments of the present invention, the nucleating agent, calculated based on a total weight of 100 parts, comprises: 30-40 parts of nano-silica, 15-30 parts of talc, 10-22 parts of kaolin, 5-10 parts of calcium hypochlorite, 5-10 parts of sodium hypochlorite, 1-5 parts of antioxidant, 0.5-3 parts of dispersant, and 1-3 parts of second compatibilizer.

[0025] In some embodiments of the present invention, the antioxidant may be selected from phosphite antioxidants or sulfur-containing antioxidants, such as tris[2,4-di-tert-butylphenyl]phosphite.

[0026] In some embodiments of the present invention, the dispersant may be polyethylene low molecular weight wax, etc.

[0027] In some embodiments of the present invention, the second compatibilizer may be maleic anhydride grafted with POE, etc.

[0028] In some embodiments of the present invention, the amount of nucleating agent added is 5% to 30% of the mass of the nylon 5T and 5I mixed salt solution.

[0029] In some embodiments of the present invention, the specific surface area of ​​the tubular reactor is greater than 80 m². 2 / m 3 It is equipped with a pressure regulating device with a control range of 0 to 10 MPa.

[0030] In some embodiments of the present invention, the reaction time of the final polymerization reaction is 1.5 to 3 hours, the reaction pressure is 1.5 to 4 MPa, and the reaction temperature is 220 to 260°C.

[0031] In some embodiments of the present invention, the tackifier may be BASF nylon polyester tackifier ADR4370.

[0032] In some embodiments of the present invention, the amount of the tackifier added is 0.2% to 2% of the mass of the transparent nylon resin.

[0033] In some embodiments of the present invention, the first compatibilizer may be maleic anhydride grafted with POE.

[0034] In some embodiments of the present invention, the amount of the first compatibilizer added is 0.5% to 2% of the mass of the transparent nylon resin.

[0035] In some embodiments of the present invention, the solid phase thickening process is carried out at a temperature of 200–280°C for 1–6 hours and at an extruder speed of 100–800 rpm.

[0036] Another aspect of the present invention provides a transparent bio-based nylon resin, which is obtained by any of the above preparation methods.

[0037] In some embodiments of the present invention, the light transmittance of the transparent bio-based nylon resin is 90% to 95%.

[0038] In some embodiments of the present invention, the tensile strength of the transparent bio-based nylon resin is 80-100 GPa; preferably 82-87 GPa.

[0039] In some embodiments of the present invention, the number average molecular weight of the transparent bio-based nylon resin is 20,000 to 40,000, preferably 36,000 to 39,000.

[0040] The beneficial effects of this invention include:

[0041] 1) This invention addresses the characteristics of nylon dehydration and polycondensation by introducing a tubular reactor into the nylon reaction. Compared to a reaction vessel, the tubular reactor can effectively remove the heat of reaction, precisely control the reaction temperature, effectively meet the required residence time, control the concentration distribution of reactants, and simultaneously allow for better cross-linking of the nucleating agent and nylon prepolymer, ultimately producing nylon resin with uniform molecular weight; further saving energy and improving reaction efficiency. This invention also employs a combination of a reaction vessel and a tubular reactor, which effectively controls the reaction rhythm and ensures a more complete reaction.

[0042] 2) This invention addresses the problem of nylon's excessive viscosity causing it to stick to the reactor walls and clog. The solid-phase viscosity-enhancing process of nylon is carried out after it is introduced into the extruder. Compared to the reactor, the extruder does not require vacuum polycondensation, and the reaction conditions are more mild and controllable, allowing the molecular weight of nylon to increase stably. Subsequently, it is directly traction extruded without causing clogging.

[0043] 3) This invention addresses the problem that transparent nylon resin materials are prone to oxidation and yellowing during storage and transportation when exposed to light, thus affecting the appearance and performance of nylon. A nucleating agent is designed to further improve the light transmittance of nylon resin, so that transparent bio-based nylon resin will not be oxidized for a longer period of time and will not have yellowing problems, thus giving the resin a better service life. Detailed Implementation

[0044] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0045] This invention provides a novel polymerization method for transparent bio-based nylon materials. By using a tubular reactor in a reaction vessel, the time, temperature, and reactant concentration distribution of the nylon polycondensation reaction are controlled, resulting in a more uniform molecular weight distribution, more stable performance, improved reaction efficiency, and reduced energy consumption. Simultaneously, a novel nucleating agent is provided, which not only improves the transparency of the nylon resin but also solves the problem of nylon resin's susceptibility to oxidation and yellowing. Furthermore, the risk of reaction equipment blockage is reduced by solid-phase thickening in the extruder, providing a more feasible method for the efficient production of transparent bio-based nylon resin.

[0046] The method for preparing the transparent bio-based nylon material provided by this invention includes the following steps:

[0047] S1, bio-based pentanediamine reacts with terephthalic acid and isophthalic acid to form a salt, yielding a mixed salt of nylon 5T and 5I;

[0048] S2. The nylon 5T and 5I mixed salt undergoes a prepolymerization reaction under the action of a catalyst to obtain nylon 5T and 5I prepolymers;

[0049] S3. The obtained prepolymer and nucleating agent are added to a tubular reactor to carry out a final polymerization reaction to obtain transparent nylon resin.

[0050] S4. The obtained transparent nylon resin is pressurized and fed into an extruder, and a tackifier and a first compatibilizer are added for solid-phase tackification. Then, it is drawn into strips and fed into a pelletizer for pelletizing. After drying, transparent bio-based nylon resin chips are obtained.

[0051] The following provides a detailed explanation of each step:

[0052] S1, bio-based pentanediamine reacts with terephthalic acid and isophthalic acid to form a salt, yielding a mixed salt of nylon 5T and 5I.

[0053] The molar ratio of the bio-based pentanediamine to terephthalic acid and isophthalic acid is 1:(1-1.2). The ratio of terephthalic acid to isophthalic acid affects the transparency of the resulting nylon material; preferably, the molar ratio of terephthalic acid to isophthalic acid is 1:(2-4).

[0054] In some specific embodiments of the present invention, the salt formation reaction is carried out in water, and the resulting Nylon 5T and 5I mixed salt solution is used directly for the next reaction without further treatment. It is added to the reactor with the catalyst to carry out the prepolymerization reaction to obtain the Nylon 5T and 5I prepolymer.

[0055] In some specific embodiments of the present invention, the reaction temperature of the salt formation reaction is 60-90°C and the reaction time is 0.5-2h.

[0056] In some specific embodiments of the present invention, the mass ratio of the nylon 5T, 5I mixed salt to water is 1:(0.3~0.8).

[0057] S2. The nylon 5T and 5I mixed salt undergoes a prepolymerization reaction under the action of a catalyst to obtain the nylon 5T and 5I prepolymer.

[0058] The prepolymerization reaction is carried out in a reactor. Preferably, the reaction temperature of the prepolymerization reaction is 120-160°C, the reaction pressure is 1.5-4 MPa, and the reaction time is 0.5-2 h.

[0059] In some specific embodiments of the present invention, the catalyst is a combination of anhydrous acetic acid and sodium hypochlorite; the amount of catalyst added is preferably 0.3% to 2% of the mass of the nylon 5T and 5I mixed salt solution.

[0060] S3. The obtained prepolymer and nucleating agent are added to a tubular reactor for final polymerization to obtain transparent nylon resin.

[0061] The final polymerization reaction is carried out in a tubular reactor, preferably with a specific surface area greater than 80 m². 2 / m 3 It is equipped with a pressure regulating device with a control range of 0 to 10 MPa.

[0062] Compared to a reaction vessel, a tubular reactor can effectively remove the heat of reaction, precisely control the reaction temperature, effectively meet the required residence time, control the concentration distribution of reactants, and simultaneously allow for better cross-linking of the nucleating agent and nylon prepolymer, ultimately producing nylon resin with uniform molecular weight; it also further saves energy and improves reaction efficiency. This invention employs a combination of a reaction vessel and a tubular reactor, which effectively controls the reaction rhythm and ensures a more complete reaction.

[0063] In some specific embodiments of the present invention, the nucleating agent, calculated based on a total weight of 100 parts, includes: 30-40 parts of nano-silica, 15-30 parts of talc, 10-22 parts of kaolin, 5-10 parts of calcium hypochlorite, 5-10 parts of sodium hypochlorite, 1-5 parts of antioxidant, 0.5-3 parts of dispersant, and 1-3 parts of second compatibilizer.

[0064] Nano-silica, talc, and kaolin are the main components of the nucleating agent. Calcium hypochlorite and sodium hypochlorite have both catalytic and anti-yellowing effects. The components and proportions of the nucleating agent developed in this invention can achieve optimal transparency and anti-yellowing effects.

[0065] In some specific embodiments of the present invention, the antioxidant is a phosphite antioxidant or a sulfur-containing antioxidant, such as tris[2,4-di-tert-butylphenyl]phosphite or dibutyl pyrophosphate; the dispersant is a low molecular weight polyethylene wax; and the second compatibilizer is maleic anhydride-grafted POE.

[0066] In some specific embodiments of the present invention, the amount of nucleating agent added is 5% to 30% of the mass of the nylon 5T and 5I mixed salt solution.

[0067] In some specific embodiments of the present invention, the reaction time of the final polymerization reaction is 1.5 to 3 hours, the reaction pressure is 1.5 to 4 MPa, and the reaction temperature is 220 to 260°C.

[0068] S4. The obtained transparent nylon resin is pressurized and fed into an extruder, and a tackifier and a first compatibilizer are added for solid-phase tackification. Then, it is drawn into strips and fed into a pelletizer for pelletizing. After drying, transparent bio-based nylon resin chips are obtained.

[0069] This invention performs the solid-phase thickening process of nylon after it is introduced into the extruder. Compared with the reactor, the extruder does not need to perform vacuum polycondensation, and the reaction conditions are more mild and controllable, which allows the molecular weight of nylon to increase stably. Then, it can be directly traction extruded without causing clogging problems.

[0070] The tackifier can be any conventional tackifier in the art, such as BASF nylon polyester tackifier ADR4370 used in some specific embodiments of the present invention. The preferred amount of the tackifier added is 0.2% to 2% of the mass of the transparent nylon resin.

[0071] In some specific embodiments of the present invention, the first compatibilizer is maleic anhydride-grafted POE. The preferred amount of the first compatibilizer added is 0.5% to 2% of the mass of the transparent nylon resin.

[0072] In some specific embodiments of the present invention, during the solid-phase thickening process, the temperature is 200-280°C, the time is 1-6 hours, and the extruder speed is 100-800 rpm.

[0073] The transparent bio-based nylon resin obtained by any of the above preparation methods preferably has a light transmittance of 90% to 95%; a tensile strength preferably of 80 to 100 GPa, more preferably of 82 to 87 GPa; and a number-average molecular weight preferably of 20,000 to 40,000, more preferably of 36,000 to 39,000.

[0074] The following specific examples are provided for illustration, wherein all numerical specifications (e.g., temperature, time, concentration, and weight, including ranges for each) are generally approximate values ​​that may be changed in increments of 0.1 or 1.0 (+) or (-). All numerical specifications are to be understood as being preceded by the term "about".

[0075] The nucleating agent used in the following examples and comparative examples has the following formulation: 40 parts nano-silica, 20 parts talc, 15 parts kaolin, 10 parts calcium hypochlorite, 10 parts sodium hypochlorite, 2 parts antioxidant, 2 parts dispersant, and 1 part second compatibilizer. The antioxidant is tris[2,4-di-tert-butylphenyl]phosphite; the dispersant is low molecular weight polyethylene wax; and the second compatibilizer is maleic anhydride-grafted POE.

[0076] The tackifier is BASF nylon polyester tackifier ADR4370; the first compatibilizer is maleic anhydride grafted POE.

[0077] Example 1

[0078] The following embodiments are all based on this experimental procedure, including:

[0079] S1. Take 16.62g of terephthalic acid and 66.45g of isophthalic acid and add them to 41.2g of purified water. Heat the mixture to 80℃ and start stirring. After the terephthalic acid and isophthalic acid dissolve, slowly add 51.09g of bio-based pentanediamine under nitrogen protection. Continue stirring at 80℃ for 1 hour. Stop the reaction when the solution becomes transparent. At this time, the pH value of the obtained nylon 5T and 5I salt solution is measured to be 6.8.

[0080] S2. Take 100g of the prepared nylon 5T and 5I salt solution and place it into a reaction vessel. Add 0.5g of anhydrous acetic acid and 0.5g of sodium hypochlorite dropwise. Purge with nitrogen three times until there is no air in the vessel. Under nitrogen protection, carry out the prepolymerization reaction at 140℃. After reacting for 1 hour, the prepolymer of nylon 5T and 5I is obtained.

[0081] S3. The prepolymers of nylon 5T and 5I are introduced into a tubular reactor, and 30g of nucleating agent is added. After sealing the tubular reactor, the temperature is raised to 240℃ and reacted for 3 hours to obtain nylon 5T and 5I molten resin.

[0082] S4. The obtained nylon 5T and 5I molten resins are further pressurized (just apply a little pressure to ensure they enter the extruder smoothly) and fed into the extruder. 2.8g of tackifier and 2g of compatibilizer are added, and solid-phase tackification is carried out in the extruder. During solid-phase tackification, the extruder temperature is 240℃, the extruder speed is 500rpm, and the reaction is carried out in the extruder for 5 hours. Then, the resin is drawn into strips and fed into a pelletizer for pelletizing. After drying, transparent bio-based nylon resin chips are obtained.

[0083] Table 1 shows the mass, number-average molecular weight, and tensile strength of the nylon products obtained by changing the molar ratio of isophthalic acid, terephthalic acid, and pentanediamine under the experimental conditions described above.

[0084] Table 1

[0085]

[0086] As shown in Table 1, when the ratio of diamine to diacid is 1:(1 to 1.2), the molecular weight of the resulting nylon resin ranges from 38,000 to 39,000, and the tensile strength is between 82 and 86 GPa.

[0087] Example 2

[0088] Example 2 is similar to Examples 1-2, except that the mass of purified water added in the salt formation reaction is different. In Example 2, the amount of purified water added is changed, resulting in different mass ratios of 5T and 5I salts to purified water. The mass, number-average molecular weight, and tensile strength of the final nylon product are shown in Table 2.

[0089] Table 2

[0090]

[0091] As shown in Table 2, when the mass ratio of nylon 5T and 5I salt to pure water is 1:(0.3 to 0.8), the molecular weight of the resulting nylon resin ranges from 36,000 to 39,000, and the tensile strength is between 83 and 86 GPa.

[0092] Example 3

[0093] Example 3 is similar to Examples 2-2, except that the mass of anhydrous acetic acid and sodium hypochlorite catalysts added to the reactor is different. In Example 3, the amount of anhydrous ethanol and sodium hypochlorite added was changed. The mass, number-average molecular weight and tensile strength of the final nylon product are shown in Table 3.

[0094] Table 3

[0095]

[0096] As shown in Table 3, when the ratio of anhydrous acetic acid and sodium hypochlorite in the nylon 56 salt solution is 0.3% to 2%, the molecular weight of the resulting nylon resin ranges from 38,000 to 39,000, and the tensile strength is between 84 and 86 GPa.

[0097] Example 4

[0098] Example 4 is similar to Examples 3-3, except that the reaction temperature of the prepolymerization reaction in the reactor is different. In Example 4, the reaction temperature of the prepolymerization reaction in the reactor, the pressure in the reactor, and the data of the final nylon product mass, number-average molecular weight and tensile strength are shown in Table 4.

[0099] Table 4

[0100]

[0101] As shown in Table 4, when the prepolymerization temperature in the reactor is 120-140℃, the molecular weight of the obtained nylon resin ranges from 38,000 to 39,000, and the tensile strength is between 84 and 86 GPa.

[0102] Example 5

[0103] Example 5 is similar to Examples 4-2, except that the reaction time of the prepolymerization reaction in the reactor is different. In Example 5, the reaction time of the prepolymerization reaction in the reactor was changed, and the data of the final nylon product mass, number-average molecular weight and tensile strength are shown in Table 5.

[0104] Table 5

[0105]

[0106] As shown in Table 5, when the prepolymerization reaction time in the reactor is 0.5 to 2 hours, the molecular weight of the obtained nylon resin ranges from 37,000 to 39,000, and the tensile strength is between 83 and 87 GPa.

[0107] Example 6

[0108] Example 6 is similar to Examples 5-3, except that the mass of the nucleating agent added in the reaction tube is different. In Example 6, the mass of the nucleating agent added in the reaction tube was changed. The data on the mass of the final nylon product, its number-average molecular weight, tensile strength and resin transparency are shown in Table 6.

[0109] Table 6

[0110]

[0111] As shown in Table 6, when the nucleating agent accounts for 5% to 30% of the mass of the nylon salt solution, the molecular weight of the resulting nylon resin ranges from 37,000 to 39,000, and the tensile strength is between 83 and 87 GPa.

[0112] Example 7

[0113] Example 7 is similar to Examples 6-4, except that the reaction temperature of the final polymerization reaction in the reaction tube is different. In Example 7, the reaction temperature of the final polymerization reaction in the reaction tube, the pressure in the reaction tube, and the data of the final nylon product mass, number-average molecular weight and tensile strength are shown in Table 7.

[0114] Table 7

[0115]

[0116] As shown in Table 7, when the reaction temperature for the final polymerization reaction in the tubular reactor is 220–240℃, the molecular weight of the obtained nylon resin ranges from 38,000 to 39,000, and the tensile strength is between 84 and 86 GPa.

[0117] Example 8

[0118] Example 8 is similar to Examples 7-2, except that the reaction time of the final polymerization reaction in the reaction tube is different. In Example 8, the reaction time of the final polymerization reaction in the reaction tube was changed, and the data of the final nylon product mass, its number-average molecular weight and tensile strength are shown in Table 8.

[0119] Table 8

[0120]

[0121] As shown in Table 8, when the reaction time for the final polymerization reaction in the tubular reactor is 1.5 to 3 hours, the molecular weight of the obtained nylon resin ranges from 37,000 to 39,000, and the tensile strength is between 84 and 86 GPa.

[0122] Example 9

[0123] Example 9 is similar to Examples 8-3, except that the mass of the thickener or first compatibilizer added during solid-phase thickening in the extruder is different. In Example 9, the mass of the thickener or first compatibilizer added was changed, and the data of the mass of the final nylon product, its number-average molecular weight, and tensile strength are shown in Tables 9 and 10.

[0124] Table 9

[0125]

[0126] Table 10

[0127]

[0128] As shown in Table 9, when the amount of tackifier added to nylon 56 resin is 0.2% to 2%, the molecular weight of the resulting nylon resin ranges from 36,000 to 39,000, and the tensile strength is between 84 and 87 GPa.

[0129] As shown in Table 10, when the amount of the first compatibilizer added is 0.5% to 2%, the molecular weight of the resulting nylon resin is in the range of 37,000 to 38,000, and the tensile strength is between 85 and 86 GPa.

[0130] Example 10

[0131] Example 10 is similar to Examples 9-3, except that the reaction temperature during solid-phase thickening in the extruder is different. In Example 10, the reaction temperature of the extruder was changed, and the data on the final nylon product mass, number-average molecular weight, and tensile strength are shown in Table 11.

[0132] Table 11

[0133]

[0134] As shown in Table 11, when the solid-phase thickening reaction temperature is 220-240℃, the molecular weight of nylon resin is 38,000-39,000, and the tensile strength is in the range of 84-86 GPa.

[0135] Example 11

[0136] Example 11 is similar to Examples 10-2, except that the reaction time for solid-phase thickening in the extruder is different. In Example 11, the reaction time for solid-phase thickening in the extruder was changed, and the final nylon product mass, number-average molecular weight, and tensile strength data are shown in Table 12.

[0137] Table 12

[0138]

[0139] As shown in Table 12, when the solid-phase thickening reaction time is 1 to 5 hours, the molecular weight of the nylon resin ranges from 36,000 to 39,000, and the tensile strength is in the range of 83 to 86 GPa.

[0140] Comparative Example 1

[0141] In this comparative example, the final polymerization reaction was carried out in a reactor.

[0142] S1. Take 16.62g of terephthalic acid and 66.45g of isophthalic acid and put them into 41.2g of purified water. After heating to 80℃, start stirring. After the terephthalic acid and isophthalic acid dissolve, under nitrogen protection, slowly add 51.09g of bio-based pentanediamine. Continue stirring at 80℃ for 1 hour. Stop the reaction when the solution becomes clear. At this time, the pH value of the obtained nylon 5T and 5I salt solution is measured to be 6.8.

[0143] S2. Take 100g of the prepared nylon 5T and 5I salt solution and 30g of nucleating agent and put them into a reaction vessel. Add 0.5g of anhydrous acetic acid and 0.5g of sodium hypochlorite dropwise. Purge with nitrogen three times until there is no air in the vessel. Under nitrogen protection, carry out a prepolymerization reaction at 140℃ for 1 hour. Then raise the temperature to 220℃ and continue the final polymerization reaction for 3 hours to obtain a transparent bio-based nylon melt resin.

[0144] S3. Continue to feed the transparent bio-based nylon molten resin into the extruder, and add 2.8g of tackifier and 2g of compatibilizer. Perform solid-phase tackification in the extruder. During solid-phase tackification, the extruder temperature is 240℃, the extruder speed is 500rpm, and the reaction is carried out in the extruder for 5 hours. Then, the resin is drawn into strips and fed into a pelletizer for pelletizing. After drying, transparent bio-based nylon resin chips are obtained.

[0145] Under the same conditions as above, only the final polymerization reaction steps were changed in this comparative example. The resulting nylon 56 resin had a mass of 135.12 g, a number-average molecular weight of 35,500, and a tensile strength of 82.63 GPa.

[0146] As can be seen from this comparative example compared with Example 1, under the same conditions except that the final polymerization reaction in the reaction tube is omitted, the yield of the final nylon product, as well as the number-average molecular weight and tensile strength, will be reduced.

[0147] Comparative Example 2

[0148] This comparative example demonstrates solid-phase thickening in a tubular reactor.

[0149] S1. Take 16.62g of terephthalic acid and 66.45g of isophthalic acid and put them into 41.2g of purified water. After heating to 80℃, start stirring. After the terephthalic acid and isophthalic acid dissolve, slowly add 51.09g of bio-based pentanediamine under nitrogen protection. Continue stirring at 80℃ for 1 hour. Stop the reaction when the solution becomes clear. At this time, the pH value of the obtained nylon 5T and 5I salt solution is measured to be 6.8.

[0150] S2. Take 100g of the nylon 5T and 5I salt solution prepared above and put it into a reaction vessel. Add 0.5g of anhydrous acetic acid and 0.5g of sodium hypochlorite dropwise. Purge with nitrogen three times until there is no air in the vessel. Under nitrogen protection, carry out the prepolymerization reaction at 140℃. After reacting for 1 hour, the prepolymer of nylon 5T and 5I is obtained.

[0151] S3. The prepolymers of Nylon 5T and 5I are introduced into a tubular reactor, and 30g of nucleating agent, 2.8g of tackifier and 2g of compatibilizer are added. After sealing the tubular reactor, the temperature is raised to 220℃ and reacted for 3 hours. Then the gas is released to normal pressure, and then a vacuum is drawn to 0.2-0.8MPa. After 30 minutes, Nylon 5T and 5I molten resin is obtained.

[0152] S4. Continue to feed molten nylon 5T and 5I resin into the extruder at an extruder temperature of 240℃ and an extruder speed of 500rpm for 5 hours. Then, traction and stripping are performed and the resin is fed into a pelletizer for pelletizing. After drying, transparent bio-based nylon resin chips are obtained.

[0153] Under the same conditions as above, this comparative example only changed the solid-phase thickening step, moving it to the S3 final polymerization step. The resulting nylon resin had a mass of 136.12 g, a number-average molecular weight of 35,500, and a tensile strength of 83.73 GPa.

[0154] As can be seen from the comparison with Example 1, under the same conditions, except that the solid-phase thickening step in the extruder in this application is moved to the final polymerization reaction step, the yield of the final nylon product, as well as the number-average molecular weight and tensile strength, will be reduced.

[0155] Comparative Example 3

[0156] No nucleating agent was added to this comparative example.

[0157] S1. Take 16.62g of terephthalic acid and 66.45g of isophthalic acid and add them to 67.08g of purified water. Heat the mixture to 80℃ and start stirring. After the terephthalic acid and isophthalic acid dissolve, slowly add 51.09g of bio-based pentanediamine under nitrogen protection. Continue stirring at 80℃ for 1 hour. Stop the reaction when the solution becomes transparent. At this time, the pH value of the obtained nylon 5T and 5I salt solution is measured to be 6.8.

[0158] S2. Take 100g of the prepared nylon 5T and 5I salt solution and place it into a reaction vessel. Add 1g of anhydrous acetic acid and 1g of sodium hypochlorite dropwise. Purge with nitrogen three times until there is no air in the vessel. Under nitrogen protection, carry out the prepolymerization reaction at 140℃. After reacting for 2 hours, the prepolymer of nylon 5T and 5I is obtained.

[0159] S3. The prepolymers of nylon 5T and 5I are introduced into a tubular reactor. After sealing the tubular reactor, the temperature is raised to 220°C and reacted for 3 hours to obtain molten nylon 5T and 5I resin.

[0160] S4. Continue to feed nylon 5T and 5I molten resin into the extruder, add 2.8g of tackifier and 2g of compatibilizer, and carry out solid-phase tackification in the extruder. During solid-phase tackification, the extruder temperature is 240℃ and the extruder speed is 500rpm. After reacting in the extruder for 5 hours, the resin is then drawn into strips and fed into a pelletizer for pelletizing. After drying, transparent bio-based nylon resin chips are obtained.

[0161] Under the same conditions as described above, but without the addition of a nucleating agent, the comparative example yielded 137.12 g of nylon resin with a number-average molecular weight of 37,000, a tensile strength of 84.63 GPa, and a transparency of only 75%. Furthermore, the resin exhibited yellowing after 24 hours of exposure to ultraviolet light at room temperature, with a yellowing value ΔE of 26.4. In contrast, the nylon resin with the addition of a nucleating agent in the present invention did not exhibit yellowing after 24 hours of exposure to ultraviolet light at room temperature, with a yellowing value ΔE of 12.2.

[0162] As can be seen from the comparison with Example 6, under the same conditions except that no nucleating agent was added, the light transmittance of the final nylon product decreased significantly and yellowing was obvious.

[0163] Example 12

[0164] Example 12 is similar to Examples 6-4, except that the proportion of the nucleating agent added in the reaction tube is different. In Example 12, the nucleating agent added in the reaction tube was changed, and the final nylon product mass, number-average molecular weight, tensile strength, resin transparency, and yellowing value are shown in Tables 13, 14, and 15. Except for the changes in the proportions of the components listed in the tables, the proportions of other components remained unchanged, either increased or decreased proportionally.

[0165] Table 13

[0166]

[0167] As shown in Table 13, nano-silica can improve the transparency of nylon resin. When the addition amount is 30% to 40%, the transparency is 92% to 94%.

[0168] Table 14

[0169]

[0170] In Table 14, the ratio between talc and kaolin remains unchanged. As can be seen from the data in Table 13, talc and kaolin can improve the transparency of nylon resin. When the addition amount is 30% to 40%, the transparency is 93% to 94%.

[0171] Table 15

[0172]

[0173] In Table 15, the ratio between calcium hypochlorite and sodium hypochlorite remains unchanged. As can be seen from the data in Table 14, calcium hypochlorite and sodium hypochlorite can further improve the yellowing resistance of nylon resin. When the addition amount is 10% to 20%, the yellowing value is between 12 and 19.

[0174] The tensile strength involved in the above embodiments and comparative examples was measured using a universal tensile testing machine, the number-average molecular weight was determined using GPC gel chromatography, the transparency was tested according to "GB 2410-1980 Test Method for Light Transmittance of Transparent Plastics", and the yellowing was tested according to "GB / T 7921—2008".

[0175] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a transparent bio-based nylon resin, wherein, The preparation method includes the following steps: Bio-based pentanediamine reacts with terephthalic acid and isophthalic acid to form a salt, yielding a mixed salt of nylon 5T and 5I. The salt formation reaction is carried out in water. The resulting mixed salt solution of nylon 5T and 5I is added to the reactor along with the catalyst to carry out a prepolymerization reaction, thereby obtaining the prepolymer of nylon 5T and 5I. The obtained prepolymer and nucleating agent were added to a tubular reactor for final polymerization to obtain transparent nylon resin; The obtained transparent nylon resin was pressurized and fed into an extruder, and a tackifier and a first compatibilizer were added for solid-phase tackification. Then, it was drawn into strips and fed into a pelletizer for pelletizing. After drying, transparent bio-based nylon resin chips were obtained. The nucleating agent, calculated based on a total weight of 100 parts, includes: 30-40 parts of nano-silica, 15-30 parts of talc, 10-22 parts of kaolin, 5-10 parts of calcium hypochlorite, 5-10 parts of sodium hypochlorite, 1-5 parts of antioxidant, 0.5-3 parts of dispersant, and 1-3 parts of second compatibilizer. The amount of nucleating agent added is 5% to 30% of the mass of the nylon 5T and 5I mixed salt solution.

2. The preparation method according to claim 1, wherein, The antioxidant is selected from phosphite antioxidants or sulfur-containing antioxidants.

3. The preparation method according to claim 1, wherein, The dispersant is a low molecular weight polyethylene wax.

4. The preparation method according to claim 1, wherein, Both the first compatibilizer and the second compatibilizer are maleic anhydride-grafted POE.

5. The preparation method according to claim 1, wherein, The molar ratio of the bio-based pentanediamine to terephthalic acid and isophthalic acid is 1:(1~1.2).

6. The preparation method according to claim 1, wherein, The molar ratio of terephthalic acid to isophthalic acid is 1:(2~4).

7. The preparation method according to claim 1, wherein, The salt formation reaction is carried out at a temperature of 60-90℃ for a time of 0.5-2 h.

8. The preparation method according to claim 1, wherein, The mass ratio of the nylon 5T and 5I mixed salt to water is 1:(0.3~0.8).

9. The preparation method according to claim 1, wherein, The catalyst is a combination of anhydrous acetic acid and sodium hypochlorite in a molar ratio of 1:

1.

10. The preparation method according to claim 9, wherein, The catalyst is added at a rate of 0.3% to 2% of the mass of the nylon 5T and 5I mixed salt solution.

11. The preparation method according to claim 1, wherein, The reaction temperature of the prepolymerization reaction is 120~160℃, and the reaction time is 0.5~2 h.

12. The preparation method according to claim 1, wherein, The specific surface area of ​​the tubular reactor is greater than 80 m². 2 / m 3 It is equipped with a pressure regulating device with a control range of 0~10 MPa.

13. The preparation method according to claim 1, wherein, The reaction time for the final polymerization reaction is 1.5 to 3 hours, and the reaction temperature is 220 to 260°C.

14. The preparation method according to claim 1, wherein, The amount of the tackifier added is 0.2% to 2% of the mass of the transparent nylon resin.

15. The preparation method according to claim 1, wherein, The amount of the first compatibilizer added is 0.5% to 2% of the mass of the transparent nylon resin.

16. The preparation method according to claim 1, wherein, During the solid-phase thickening process, the temperature is 200~280℃ and the time is 1~6 h.

17. A transparent bio-based nylon resin obtained by the preparation method according to any one of claims 1-16.

18. The transparent bio-based nylon resin according to claim 17, wherein, The transparent bio-based nylon resin has a light transmittance of 90%~95%, a tensile strength of 80~100 GPa, and a number-average molecular weight of 20000~40000.

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