A block copolymer nylon and its preparation method

Abstract

The present invention provides a block copolymerized nylon and a preparation method thereof. The preparation method includes carrying out polymerization reactions on at least two nylon salts respectively in the presence of a catalyst and a capping agent to obtain a double-ended nylon oligomer, and then carrying out polycondensation reaction on the obtained double-ended nylon oligomer to obtain the block copolymerized nylon. The present invention can obtain a block copolymerized nylon product with high strength, good toughness, low water absorption and good softness.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and specifically, to a block copolymerized nylon and a preparation method thereof. Background Art

[0002] Copolymerized nylon is a copolymer. Usually, the copolymerized nylon prepared is a random copolymer, which has a low melting point and poor performance, and is mainly used as a hot melt adhesive. For example, nylon 1212 is a long-chain nylon, which has the characteristics of low density, low water absorption rate, good dimensional stability, excellent chemical resistance, corrosion resistance, wear resistance, fatigue resistance and good low-temperature impact resistance. It is mainly used in industries such as automobiles, electrical appliances and machinery, such as coil skeletons, insulating layers of wires and cables, fuel oil pipelines, oil pressure system pipelines, conduits, etc. For example, nylon 66 is a short-chain nylon, which has higher toughness and strength. Making nylon 1212 and nylon 66 into block copolymerized nylon combines the strength and toughness of nylon 66 and the low water absorption and low-temperature resistance of nylon 1212, has better softness, lower water absorption rate, more stable product dimensions, and wear resistance, and can be used in industries such as automobiles and electronics.

[0003] The properties of block copolymerized nylon can be regulated by controlling the segment ratio. Compared with nylon salt copolymers directly copolymerized from nylon salts, it has a higher melting point, stronger strength and wear resistance. Summary of the Invention

[0004] In order to overcome the problems of low melting point, low strength and poor toughness of copolymerized nylon in the prior art, the present invention provides a block copolymerized nylon and a preparation method thereof.

[0005] One object of the present invention is to provide a preparation method of block copolymerized nylon, which includes carrying out a polymerization reaction on at least two nylon salts in the presence of a catalyst and a capping agent to obtain a double-end-based nylon oligomer, and then carrying out a polycondensation reaction on the obtained at least two double-end-based nylon oligomers to obtain block copolymerized nylon.

[0006] In the preparation method, the nylon salt is prepared from a diamine and a diacid; wherein, the diamine is selected from diamines having 5 to 20 carbon atoms, and the diacid is selected from diacids having 5 to 20 carbon atoms.

[0007] The molar ratio of the diacid to the diamine is 1:(1 - 1.05), preferably 1:(1 - 1.01).

[0008] Preferably, the method of the present invention is used to prepare block copolymer nylon of long-chain nylon and short-chain nylon. The long-chain nylon oligomer is prepared from a long-chain diamine and a long-chain dibasic acid. The diamine can be a C10-C20 long-chain diamine, and the dibasic acid can be a C10-C20 long-chain dibasic acid. The short-chain nylon oligomer is prepared from a short-chain diamine and a short-chain dibasic acid. The diamine can be a C5-C6 short-chain diamine, and the dibasic acid can be a C5-C6 short-chain dibasic acid. For example, a block copolymer of nylon 66 or nylon 56 and nylon 1212 or nylon 1012 is obtained.

[0009] In the preparation method, the nylon salt is preferably prepared by the following steps:

[0010] a) Mix the dibasic acid with solvent A and heat-treat to obtain solution A;

[0011] b) Mix the diamine with solvent B and heat-treat to obtain solution B;

[0012] c) Add solution B to solution A and react to obtain the nylon salt.

[0013] Among them, in step a), the solvent A is selected from at least one of methanol, ethanol, and propanol. The weight ratio of the dibasic acid to solvent A is 1:(2-10), preferably 1:(3-7). Heat to 50-95°C and keep for 10-50 min, preferably heat to 60-75°C and keep for 20-40 min.

[0014] In step b), the solvent B is selected from at least one of methanol, ethanol, and propanol. The weight ratio of the diamine to solvent B is 1:(1-6), preferably 1:(1-3). Heat to 40-90°C and keep for 10-50 min, preferably heat to 50-70°C and keep for 20-40 min.

[0015] In step c), the reaction is carried out at 50-100°C for 0.2-4 h. Preferably, the reaction is carried out at 70-80°C for 0.5-2 h.

[0016] After step c), cool to below 40°C, preferably cool to below 30°C, and then filter and dry to obtain the nylon salt.

[0017] In the preparation method, at least two nylon salts are respectively subjected to a polymerization reaction in the presence of a catalyst and a capping agent to obtain a double-ended nylon oligomer.

[0018] Each of the bifunctional nylon oligomers is obtained by subjecting raw materials including nylon salt, water, a catalyst, and a capping agent to a hydrothermal polymerization reaction, where the reaction temperature is 150 to 220 °C, the reaction pressure is 0.8 to 2.0 MPa, and the reaction time is 0.5 to 6.0 h; preferably, the reaction temperature is 180 to 200 °C, the reaction pressure is 1.0 to 1.5 MPa, and the reaction time is 1 to 6.0 h.

[0019] The capping agent is selected from at least one of dibasic acids and diamines, and among at least two nylon salts, one uses a dibasic acid capping agent and the other uses a diamine capping agent; preferably, the diamine is selected from diamines having 5 to 20 carbon atoms, and the dibasic acid is selected from dibasic acids having 5 to 20 carbon atoms.

[0020] The dosage of the capping agent is preferably 0.05 to 1.0 wt% of the nylon salt, more preferably 0.1 to 0.5 wt%.

[0021] The catalyst is selected from at least one of phosphoric acid, phosphorous acid, hypophosphorous acid, sodium phosphite, and sodium hypophosphite.

[0022] The dosage of the catalyst is preferably 0.05 to 0.5 wt% of the nylon salt, more preferably 0.1 to 0.3 wt%.

[0023] The dosage of water is preferably 50 to 200 wt% of the nylon salt, more preferably 100 to 150 wt%.

[0024] In the preparation of the nylon oligomer, the raw materials further include an antioxidant, and the antioxidant is preferably selected from at least one of bis(2,4 - di - tert - amylphenyl)pentaerythritol diphosphite, antioxidant 1790, antioxidant 3114, antioxidant 1010, and antioxidant 1098.

[0025] The dosage of the antioxidant is preferably 0.05 to 0.5 wt% of the nylon salt, more preferably 0.1 to 0.3 wt%.

[0026] In the preparation method, the polycondensation reaction includes: mixing raw materials including at least two bifunctional nylon oligomers, water, and a molecular weight regulator, heating and increasing the pressure for reaction; reducing the pressure to atmospheric pressure; and continuing the reaction at atmospheric pressure to obtain the block copolymer nylon.

[0027] Preferably, the polycondensation reaction may include: mixing raw materials including at least two double-ended nylon oligomers, water, and a molecular weight regulator, heating to 180 - 240 °C, increasing the pressure to 1.2 - 2.2 MPa, and reacting for 0.2 - 5.0 h. More preferably, reacting at 200 - 220 °C and 1.5 - 2.0 MPa for 0.5 - 4.0 h; slowly releasing gas to maintain the pressure in the system at 1.2 - 2.5 MPa within the first 0.2 - 3.0 h and reducing it to atmospheric pressure within the subsequent 0.2 - 4.0 h. More preferably, slowly releasing gas to maintain the pressure in the system at 1.5 - 2.0 MPa within the first 0.5 - 2.0 h and reducing it to atmospheric pressure within the subsequent 0.5 - 3.0 h; finally, continuing the reaction at 180 - 300 °C and atmospheric pressure for 0.2 - 8.0 h. More preferably, conducting the reaction at 200 - 260 °C for 0.5 - 6.0 h.

[0028] Among them, the molecular weight regulator is preferably at least one of monocarboxylic acid, dicarboxylic acid, monoamine, and diamine. The molecular weight regulator includes but is not limited to lauric acid, acetic acid, dodecanedioic acid, adipic acid, etc.

[0029] The dosage of the molecular weight regulator is preferably 0.05 - 1.0 wt% of the total amount of nylon oligomers, more preferably 0.1 - 0.5 wt%.

[0030] The dosage of water is 20 - 100 wt% of the total amount of nylon oligomers.

[0031] There is no particular limitation on the ratio between the double-ended nylon oligomers, which can be adjusted according to the use of the resulting block copolymer nylon; preferably, when there are two double-ended nylon oligomers, the ratio between them is (0.1:0.9) - (0.9:0.1).

[0032] The second object of the present invention is to provide the block copolymer nylon obtained by the preparation method.

[0033] The present invention prepares block copolymer nylon through steps such as neutralization and salt formation, hydrothermal polymerization of nylon oligomers, and block copolymerization of oligomers, which preferably solves the problems in the prior art such as high water absorption of short-chain nylon, insufficient strength of long-chain nylon, and low melting point and poor strength of random copolymer nylon, achieving good technical effects.

[0034] The following further elaborates on the present invention through examples. Detailed Embodiments

[0035] The following specifically describes the present invention in combination with specific examples. It is necessary to point out here that the following examples are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0036] For the raw materials used in the examples and comparative examples, if not specifically defined, they are all disclosed in the prior art. For example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0037] The present invention provides a block copolymerized nylon and a preparation method thereof. Through steps such as neutralization and salt formation, hydrothermal polymerization to prepare nylon oligomers, and block copolymerization of oligomers, a copolymerized nylon product with high strength, good toughness, low water absorption, and good softness is prepared.

[0038] According to a preferred technical solution of the present invention, the preparation method includes the following steps:

[0039] (1) Two different nylon salts are respectively prepared by neutralizing a diamine with a dicarboxylic acid;

[0040] (2) One nylon salt, distilled water, a catalyst, a capping agent, and an antioxidant are added to a polymerization kettle, heated to about 150 - 220 °C for hydrothermal polymerization reaction. After cooling, filtering, drying, and pelletizing, a nylon oligomer is obtained;

[0041] (3) The other nylon salt, distilled water, a catalyst, a capping agent, and an antioxidant are added to a polymerization kettle, heated to about 150 - 220 °C for hydrothermal polymerization reaction. After cooling, filtering, drying, and pelletizing, another nylon oligomer is obtained;

[0042] (4) The two nylon salt oligomers, distilled water, a molecular weight regulator, etc. are added to a polymerization kettle. After heating, pressure reduction, and final polycondensation reaction, a block copolymerized nylon product is obtained.

[0043] In the above technical solution, the nylon salts in step (1) are preferably a long-chain nylon salt and a short-chain nylon salt respectively.

[0044] According to a more preferred technical solution, the long-chain nylon salt is nylon 1212 salt or nylon 1012 salt, and the short-chain nylon salt is nylon 66 salt or nylon 56 salt.

[0045] In the above technical solution, the specific process of salt formation in step (1) is as follows: (1-1) Add a dibasic acid and 2 to 10 times the amount of ethanol to a neutralization kettle, heat to 50 to 95 °C for dissolution, and maintain for 10 to 50 minutes; (1-2) Add a diamine with a molar ratio of 1.0 to 1.05 to the dibasic acid and 1 to 6 times the amount of ethanol to a dissolution kettle, heat to 40 to 90 °C for dissolution, and maintain for 10 to 50 minutes; (1-3) Pump all the diamine ethanol solution into the neutralization kettle, react while stirring, control the reaction temperature at 50 to 100 °C, continue to react for 0.2 to 4 hours after adding the materials, cool the neutralization kettle to make the temperature drop below 40 °C, filter the neutralized solution through a filter, and dry it in a drying oven to obtain two kinds of nylon salts.

[0046] In the above technical solution, the specific process of preparing a nylon oligomer in step (2) is as follows: (2-1) Mix a kind of nylon salt, water, catalyst, capping agent, and antioxidant in a ratio of 1:0.5 to 2.0:0.05 to 0.5%:0.05 to 1.0%:0.05 to 0.5%, add them to a polymerization kettle, evacuate and replace the air in the kettle with nitrogen; (2-2) Heat up, when the temperature in the kettle rises to 150 to 220 °C and the pressure in the kettle rises to 0.8 to 2.0 MPa, maintain this temperature and pressure for reaction for 0.5 to 6.0 hours; (2-3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (2-4) Filter and dry the material to obtain nylon oligomer powder.

[0047] In the above technical solution, the specific process of preparing another nylon oligomer in step (3) is as follows: (3-1) Mix another kind of nylon salt, water, catalyst, capping agent, and antioxidant in a ratio of 1:0.5 to 2.0:0.05 to 0.5%:0.05 to 1.0%:0.05 to 0.5%, add them to a polymerization kettle, evacuate and replace the air in the kettle with nitrogen; (3-2) Heat up, when the temperature in the kettle rises to 150 to 220 °C and the pressure in the kettle rises to 0.8 to 2.0 MPa, maintain this temperature and pressure for reaction for 0.5 to 4.0 hours; (3-3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (3-4) Filter and dry the material to obtain another kind of nylon oligomer powder.

[0048] In the above technical solution, according to a preferred embodiment, the catalyst is one or a mixture of two or more of phosphoric acid, phosphorous acid, hypophosphorous acid, sodium phosphite, and sodium hypophosphite, and its dosage is 0.05 to 0.5 wt% of the nylon salt dosage; among them, the catalyst is more preferably sodium hypophosphite.

[0049] In the above technical solution, according to a preferred embodiment, the antioxidant is one or a mixture of two or more of bis(2,4-dicumylphenyl)pentaerythritol diphosphite, antioxidant 1790, antioxidant 3114, antioxidant 1010 or antioxidant 1098, and its dosage is 0.05-0.5 wt% of the nylon salt dosage; among them, antioxidant 1010 is more preferred.

[0050] In the above technical solution, the end-capping agent is one of a dicarboxylic acid and a diamine, and one of the two nylon oligomers is end-capped with a dicarboxylic acid and the other is end-capped with a diamine. According to a preferred embodiment, the dosage of the end-capping agent is 0.05-1.0 wt% of the nylon salt dosage, such as 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, etc. According to a specific embodiment, for example, the nylon 1212 oligomer uses a dodecane diamine end-capping agent, and the nylon 66 oligomer uses an adipic acid end-capping agent.

[0051] In the above technical solution, the temperature of the hydrothermal polymerization reaction is, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, etc., the pressure is 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, etc., and the reaction time is 0.5 hour, 1 hour, 2 hours, 3 hours, 4.0 hours, etc.

[0052] The method of the present invention can prepare nylon oligomers with two end groups and controllable molecular weight through methods such as salification and hydrothermal polymerization.

[0053] In the above technical solution, the specific process for preparing the block copolymer nylon in step (4) is as follows: (4-1) Mix one nylon oligomer, another nylon oligomer, distilled water, and a molecular weight regulator in a ratio of 0.1-0.9:0.9-0.1:0.2-1.0:0.05-1.0%, add them to a polymerization kettle, evacuate, and then displace the air in the kettle with nitrogen; (4-2) Heat up. When the temperature in the kettle rises to 180-240 °C and the pressure in the kettle rises to 1.2-2.2 M MPa, maintain this temperature and pressure and react for 0.2-5.0 hours; (4-3) Slowly release the gas so that the pressure in the kettle is maintained at 1.2-2.5 MPa within the first 0.2-3.0 hours, and then the pressure in the kettle drops to atmospheric pressure within the next 0.2-4.0 hours; (4-4) After reacting at the reaction temperature of 180-300 °C under atmospheric pressure for 0.2-8.0 hours, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head. After cooling, it is pelletized to obtain the block copolymer nylon product.

[0054] In the above technical solution, according to a preferred embodiment, the molecular weight regulator used in step (4) is one or a mixture of monocarboxylic acids, dicarboxylic acids, monoamines, and diamines, and its dosage is 0.05-1.0 wt% of the nylon salt dosage. Among them, lauric acid is preferably used as the molecular weight regulator.

[0055] In the above technical solution, in step (4-2), the reaction temperature is, for example, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, etc., the pressure is, for example, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, 2.1 MPa, 2.2 MPa, etc., and the reaction time is 0.2 hours, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, etc.

[0056] In the above technical solution, in step (4-4), the reaction temperature is, for example, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, etc., and the reaction time is 0.2 hours, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.

[0057] In this application, for the water absorption rate test, the specimen is immersed in distilled water at 23 °C, placed at a specified temperature for a certain period of time, the mass difference between when the specimen starts the test and after water absorption is measured, and it is expressed as the percentage of the mass difference to the initial mass.

[0058] The specific test method is as follows: Dry the test specimens in an oven at 50 °C for 24 h, then cool them to room temperature in a desiccator and weigh each specimen. Place the specimens in a container filled with distilled water, and control the water temperature at 23 °C; after soaking for 24 h, take out the specimens, quickly wipe off all the water on the surface of the specimens with a clean dry cloth or filter paper, and weigh each specimen again.

[0059] In the present invention, the tensile strength is tested according to the standard GB / T 1040.1-2006, and the impact strength is tested according to the standard GB / T 1043.1-2008.

[0060]

Example 1

[0061] 1. Nylon salt formation: (1) Add 900.5 g of dodecanedioic acid and 4500 g of ethanol to a neutralization kettle, heat to 75 °C to dissolve, and maintain for 30 minutes; (2) Add 783.5 g of dodecanediamine and 1000 of ethanol to a dissolution kettle, heat to 60 °C to dissolve, and maintain for 30 minutes; (3) Pump all the dodecanediamine ethanol solution into the neutralization kettle, react with stirring, control the reaction temperature at 78 °C, continue to react for 1.0 hour after adding the materials, cool the neutralization kettle to below 30 °C, filter the neutralized liquid through a filter, and dry it in an oven to obtain nylon 1212 salt;

[0062] Replace dodecanedioic acid with adipic acid and dodecanediamine with hexamethylenediamine, and prepare nylon 66 salt by the same steps;

[0063] 2. Hydrothermal polymerization of nylon 1212: (1) Mix 600 g of nylon 1212 salt with 600 g of water, 0.6 g of catalyst sodium hypophosphite, 0.6 g of end-capping agent dodecanediamine, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 200 °C, and the pressure in the kettle rises to 1.5 MPa, maintain this temperature and pressure and react for 3.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, and fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 1212 oligomer powder;

[0064] 3. Hydrothermal polymerization of nylon 66: (1) Mix 600 g of nylon 66 salt with 600 g of water, 0.6 g of catalyst sodium hypophosphite, 0.6 g of end-capping agent adipic acid, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 200 °C, and the pressure in the kettle rises to 1.5 MPa, maintain this temperature and pressure and react for 3.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, and fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 66 oligomer powder;

[0065] 4. Nylon Copolymerization: (1) Mix 500 g of nylon 1212 oligomer, 500 g of nylon 66 oligomer, 500 g of water, and 1.0 g of molecular weight regulator lauric acid evenly and add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat up. When the temperature in the kettle rises to 210 °C and the pressure rises to 1.8 MPa, maintain this temperature and pressure and react for 1.0 hour; (3) Slowly release the gas so that the pressure in the kettle is maintained at 1.8 MPa within the first 1.0 hour, and the pressure in the kettle drops to atmospheric pressure within the next 1.0 hour; (4) After reacting at a reaction temperature of 240 °C under atmospheric pressure for 2.0 hours, stop stirring, open the discharge valve, fill with nitrogen, the material flows out through the injection head, and is pelletized after cooling to obtain a block copolymerized nylon product.

[0066]

Example 2

[0067] The nylon salt formation step remains unchanged, and the hydrothermal polymerization steps of nylon 1212 and nylon 66 remain unchanged. The nylon copolymerization steps include:

[0068] Nylon Copolymerization: (1) Mix 100 g of nylon 1212 oligomer, 900 g of nylon 66 oligomer, 500 g of water, and 1.0 g of molecular weight regulator lauric acid evenly and add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat up. When the temperature in the kettle rises to 210 °C and the pressure rises to 1.8 MPa, maintain this temperature and pressure and react for 1.0 hour; (3) Slowly release the gas so that the pressure in the kettle is maintained at 1.8 MPa within the first 1.0 hour, and the pressure in the kettle drops to atmospheric pressure within the next 1.0 hour; (4) After reacting at a reaction temperature of 240 °C under atmospheric pressure for 2.0 hours, stop stirring, open the discharge valve, fill with nitrogen, the material flows out through the injection head, and is pelletized after cooling to obtain a block copolymerized nylon product.

[0069]

Example 3

[0070] The nylon salt formation step remains unchanged, and the hydrothermal polymerization steps of nylon 1212 and nylon 66 remain unchanged. The nylon copolymerization steps include:

[0071] Nylon Copolymerization: (1) Mix 900 g of nylon 1212 oligomer, 100 g of nylon 66 oligomer, 500 g of water, and 1.0 g of molecular weight regulator lauric acid evenly and add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat up. When the temperature in the kettle rises to 210 °C and the pressure rises to 1.8 MPa, maintain this temperature and pressure and react for 1.0 hour; (3) Slowly release the gas so that the pressure in the kettle is maintained at 1.8 MPa within the first 1.0 hour, and the pressure in the kettle drops to atmospheric pressure within the next 1.0 hour; (4) After reacting at a reaction temperature of 240 °C under atmospheric pressure for 2.0 hours, stop stirring, open the discharge valve, fill with nitrogen, the material flows out through the injection head, and is pelletized after cooling to obtain a block copolymerized nylon product.

[0072]

Example 4

[0073] Compared with Example 1, the nylon salt formation step remains unchanged, the nylon copolymerization step remains unchanged, and the hydrothermal polymerization step of nylon 1212 includes:

[0074] Hydrothermal polymerization of nylon 1212: (1) Mix 600 g of nylon 1212 salt with 600 g of water, 0.6 g of catalyst sodium hypophosphite, 3.0 g of capping agent dodecane diamine, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 200 °C, the pressure in the kettle rises to 1.5 MPa, and maintain this temperature and pressure for reaction for 3.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 1212 oligomer powder;

[0075] Hydrothermal polymerization of nylon 66: (1) Mix 600 g of nylon 66 salt with 600 g of water, 0.6 g of catalyst, 3.0 g of capping agent adipic acid, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 200 °C, the pressure in the kettle rises to 1.5 MPa, and maintain this temperature and pressure for reaction for 3.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 66 oligomer powder.

[0076]

Example 5

[0077] Compared with Example 1, the nylon salt formation step remains unchanged, the nylon copolymerization step remains unchanged, and the hydrothermal polymerization step of nylon 1212 includes:

[0078] Hydrothermal polymerization of nylon 1212: (1) Mix 600 g of nylon 1212 salt with 600 g of water, 0.6 g of catalyst sodium hypophosphite, 6.0 g of capping agent dodecane diamine, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 200 °C, the pressure in the kettle rises to 1.5 MPa, and maintain this temperature and pressure for reaction for 3.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 1212 oligomer powder;

[0079] Hydrothermal polymerization of nylon 66: (1) Mix 600 g of nylon 66 salt, 600 g of water, 0.6 g of catalyst sodium hypophosphite, 6.0 g of end-capping agent adipic acid, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 200 °C, and the pressure in the kettle rises to 1.5 MPa. Maintain this temperature and pressure for 3.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 66 oligomer powder.

[0080]

Example 6

[0081] Compared with Example 1, the nylon salt formation step remains unchanged, the nylon copolymerization step remains unchanged, and the hydrothermal polymerization step of nylon 1212 includes:

[0082] Hydrothermal polymerization of nylon 1212: (1) Mix 600 g of nylon 1212 salt, 600 g of water, 0.6 g of catalyst sodium hypophosphite, 0.6 g of end-capping agent dodecane diamine, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 180 °C, and the pressure in the kettle rises to 1.0 MPa. Maintain this temperature and pressure for 3.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 1212 oligomer powder;

[0083] Hydrothermal polymerization of nylon 66: (1) Mix 600 g of nylon 66 salt, 600 g of water, 0.6 g of catalyst, 0.6 g of end-capping agent adipic acid, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 180 °C, and the pressure in the kettle rises to 1.0 MPa. Maintain this temperature and pressure for 3.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 66 oligomer powder.

[0084]

Example 7

[0085] Compared with Example 1, the nylon salt formation step remains unchanged, the nylon copolymerization step remains unchanged, and the hydrothermal polymerization step of nylon 1212 includes:

[0086] Hydrothermal polymerization of nylon 1212: (1) Mix 600 g of nylon 1212 salt with 600 g of water, 0.6 g of catalyst sodium hypophosphite, 0.6 g of end-capping agent dodecanediamine, and 0.6 g of antioxidant 1010 evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 200 °C, and the pressure in the kettle rises to 1.5 MPa. Maintain this temperature and pressure for 6.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 1212 oligomer powder;

[0087] Hydrothermal polymerization of nylon 66: (1) Mix 600 g of nylon 66 salt with 600 g of water, 0.6 g of catalyst, 0.6 g of end-capping agent adipic acid, and 0.6 g of antioxidant evenly, and then add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat for 1.0 hour to raise the temperature to 200 °C, and the pressure in the kettle rises to 1.5 MPa. Maintain this temperature and pressure for 6.0 hours; (3) Cool to room temperature, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head; (4) Filter and dry the material to obtain nylon 66 oligomer powder.

[0088]

Example 8

[0089] The nylon salt formation step remains unchanged, and the hydrothermal polymerization steps of nylon 1212 and nylon 66 remain unchanged. The nylon copolymerization steps include:

[0090] Nylon copolymerization: (1) Mix 500 g of nylon 1212 oligomer with 500 g of nylon 66 oligomer, 500 g of water, and 1.0 g of molecular weight regulator lauric acid evenly, and add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat up. When the temperature in the kettle rises to 210 °C and the pressure rises to 1.8 MPa, maintain this temperature and pressure for 1.0 hour; (3) Slowly release the gas to keep the pressure in the kettle at 1.8 MPa within the first 1.0 hour, and then the pressure in the kettle drops to atmospheric pressure within the next 1.0 hour; (4) After maintaining the reaction temperature at 200 °C under atmospheric pressure for 2.0 hours, stop stirring, open the discharge valve, fill with nitrogen, the material flows out through the injection head, and after cooling, it is pelletized to obtain the block copolymer nylon product.

[0091]

Example 9

[0092] The nylon salt formation step remains unchanged, and the hydrothermal polymerization steps of nylon 1212 and nylon 66 remain unchanged. The nylon copolymerization steps include:

[0093] Nylon copolymerization: (1) Mix 500 g of nylon 1212 oligomer, 500 g of nylon 66 oligomer, 500 g of water, and 1.0 g of molecular weight regulator lauric acid evenly and add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat up. When the temperature in the kettle rises to 210 °C and the pressure rises to 1.8 MPa, maintain this temperature and pressure and react for 1.0 hour; (3) Slowly release the gas so that the pressure in the kettle is maintained at 1.8 MPa within the first 1.0 hour, and the pressure in the kettle drops to atmospheric pressure within the next 1.0 hour; (4) Keep the reaction temperature at 260 °C under atmospheric pressure and react for 2.0 hours, then stop stirring, open the discharge valve, fill with nitrogen, the material flows out through the injection head, and is pelletized after cooling to obtain the block copolymerized nylon product.

[0094]

Example 10

[0095] The nylon salification step remains unchanged, the hydrothermal polymerization steps of nylon 1212 and nylon 66 remain unchanged, and the nylon copolymerization steps include:

[0096] Nylon copolymerization: (1) Mix 500 g of nylon 1212 oligomer, 500 g of nylon 66 oligomer, 500 g of water, and 1.0 g of molecular weight regulator lauric acid evenly and add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat up. When the temperature in the kettle rises to 210 °C and the pressure rises to 1.8 MPa, maintain this temperature and pressure and react for 1.0 hour; (3) Slowly release the gas so that the pressure in the kettle is maintained at 1.8 MPa within the first 1.0 hour, and the pressure in the kettle drops to atmospheric pressure within the next 1.0 hour; (4) Keep the reaction temperature at 240 °C under atmospheric pressure and react for 0.5 hour, then stop stirring, open the discharge valve, fill with nitrogen, the material flows out through the injection head, and is pelletized after cooling to obtain the block copolymerized nylon product.

[0097]

Example 11

[0098] The nylon salification step remains unchanged, the hydrothermal polymerization steps of nylon 1212 and nylon 66 remain unchanged, and the nylon copolymerization steps include:

[0099] Nylon copolymerization: (1) Mix 500 g of nylon 1212 oligomer, 500 g of nylon 66 oligomer, 500 g of water, and 1.0 g of molecular weight regulator lauric acid evenly and add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat up. When the temperature in the kettle rises to 210 °C and the pressure rises to 1.8 MPa, maintain this temperature and pressure and react for 1.0 hour; (3) Slowly release the gas so that the pressure in the kettle is maintained at 1.8 MPa within the first 1.0 hour, and the pressure in the kettle drops to atmospheric pressure within the next 1.0 hour; (4) Keep the reaction temperature at 240 °C under atmospheric pressure and react for 4.0 hours, then stop stirring, open the discharge valve, fill with nitrogen, the material flows out through the injection head, and is pelletized after cooling to obtain the block copolymerized nylon product.

[0100]

Comparative Example 1

[0101] The nylon salt formation step remains unchanged. Nylon 1212 salt and nylon 66 salt are directly copolymerized. The steps include:

[0102] (1) Mix 500 g of nylon 1212 salt, 500 g of nylon 66 salt, 500 g of water, 1.0 g of catalyst sodium hypophosphite, 1.0 g of molecular weight regulator lauric acid, and 1.0 g of antioxidant 1010 evenly and add them to a 2.0 L high-temperature and high-pressure polymerization kettle; (2) Heat up. When the temperature in the kettle rises to 210 °C and the pressure rises to 1.8 MPa, maintain this temperature and pressure and react for 1.0 hour; (3) Slowly release the gas so that the pressure in the kettle remains at 1.8 MPa within the first 1.0 hour and then drops to atmospheric pressure within the next 1.0 hour; (4) After reacting at a reaction temperature of 240 °C under atmospheric pressure for 4.0 hours, stop stirring, open the discharge valve, fill with nitrogen, and the material flows out through the injection head. After cooling, it is pelletized to obtain a random copolymer nylon product.

[0103]

Comparative Example 2

[0104] Nylon 1212 and nylon 66 are not copolymerized. The prepared nylon 1212 and nylon 66 are melt-blended and extruded in a twin-screw extruder at a weight ratio of 1:1 to obtain a blend nylon, and its properties are tested. The preparation methods of nylon 1212 and nylon 66 are similar to those of the copolymer nylon in Comparative Example 1, except that the raw materials of nylon 1212 salt and nylon 66 salt are replaced with nylon 1212 salt for separate feeding; the preparation method of nylon 66 replaces the raw materials with nylon 66 salt, and the final reaction temperature is 280 °C.

[0105] The mechanical properties and water absorption of the nylon products obtained in the examples and comparative examples are tested, and the results are shown in Table 1:

[0106] Table 1

[0107] Project Melting point Tensile strength (Mpa) <![CDATA[Notched impact strength (kJ / m 2 )]]> Water absorption rate (%) Example 1 170.5 48.8 14.8 0.68 Example 2 172.1 50.1 13.9 1.53 Example 3 167.6 45.4 15.2 0.41 Example 4 161.3 42.3 13.5 0.75 Example 5 151.9 32.1 8.9 0.81 Example 6 162.1 41.5 13.3 0.7 Example 7 170.6 49.1 14.9 0.66 Example 8 170.4 45.1 13.5 0.69 Example 9 170.8 49.2 15.1 0.63 Example 10 170.2 45.2 13.6 0.71 Example 11 170.7 49.1 14.9 0.64 Comparative Example 1 135.1 21.2 7.8 0.92 Comparative Example 2 235.2 33.1 7.5 1.25

[0108] As can be seen from Table 1,

[0109] (1) By comparing the examples and comparative examples, it can be seen that block copolymer nylon has better strength and toughness than random copolymer nylon and blend nylon;

[0110] (2) By comparing the examples and comparative examples, it can be seen that block copolymer nylon has lower water absorption;

[0111] (3) From Examples 1 to 3, it can be seen that when the nylon 1212 block is the main part, the toughness is better and the water absorption is lower; when the nylon 66 block is the main part, the melting point and strength will be higher;

[0112] (4) It can be seen from Examples 1, 4, and 5 that the more end-capping agent there is, the closer the performance is to that of random copolymerization. At this time, due to almost no crystallization, the melting point, strength, and toughness all decrease;

[0113] (5) Comparing different reaction conditions, the higher the temperature and the longer the reaction time, the polymer molecular weight will increase, and the mechanical properties will be slightly higher at this time.

Claims

1. A preparation method of block copolymerized nylon, comprising obtaining a nylon oligomer with double terminal groups by subjecting at least two nylon salts to hydrothermal polymerization reaction with raw materials including nylon salt, water, catalyst, and end-capping agent, wherein the reaction temperature is 150 - 220 °C, the reaction pressure is 0.8 - 2.0 MPa, and the reaction time is 0.5 - 6.0 h. The nylon salt is prepared from diamine and dibasic acid, and the two nylon salts are a long-chain nylon salt and a short-chain nylon salt respectively; then subjecting the obtained nylon oligomer with double terminal groups to polycondensation reaction to obtain block copolymerized nylon.

2. The preparation method of block copolymerized nylon according to claim 1, characterized in that: the diamine is selected from diamines with 5 - 20 carbon atoms, the dibasic acid is selected from dibasic acids with 5 - 20 carbon atoms, and the molar ratio of the dibasic acid to the diamine is 1:(1 - 1.05).

3. The preparation method of block copolymerized nylon according to claim 2, characterized in that: the molar ratio of the dibasic acid to the diamine is 1:(1 - 1.01).

4. The preparation method of block copolymerized nylon according to claim 2, characterized in that the nylon salt is prepared by the following steps: a) Mix the dibasic acid with solvent A and perform heat treatment to obtain solution A; b) Mix the diamine with solvent B and perform heat treatment to obtain solution B; c) Add solution B to solution A and react to obtain nylon salt.

5. The preparation method of block copolymerized nylon according to claim 4, characterized in that: in step a), solvent A is selected from at least one of methanol, ethanol, and propanol, the weight ratio of the dibasic acid to solvent A is 1:(2 - 10), and it is heated to 50 - 95 °C and maintained for 10 - 50 min; and / or, in step b), solvent B is selected from at least one of methanol, ethanol, and propanol, the weight ratio of the diamine to solvent B is 1:(1 - 6), and it is heated to 40 - 90 °C and maintained for 10 - 50 min; and / or, in step c), the reaction is carried out at 50 - 100 °C for 0.2 - 4 h.

6. The preparation method of block copolymerized nylon according to claim 1, characterized in that: the end-capping agent is selected from at least one of dibasic acid and diamine, and among at least two nylon salts, one uses a dibasic acid end-capping agent and the other uses a diamine end-capping agent; and / or, the catalyst is selected from at least one of phosphoric acid, phosphorous acid, hypophosphorous acid, sodium phosphite, and sodium hypophosphite.

7. The preparation method of block copolymerized nylon according to claim 6, characterized in that: the diamine is selected from diamines with 5 - 20 carbon atoms, and the dibasic acid is selected from dibasic acids with 5 - 20 carbon atoms.

8. The preparation method of block copolymerized nylon according to claim 1, characterized in that: the water dosage is 50 - 200 wt% of the nylon salt; the end-capping agent dosage is 0.05 - 1.0 wt% of the nylon salt; the catalyst dosage is 0.05 - 0.5 wt% of the nylon salt.

9. The preparation method of block copolymerized nylon according to claim 1, characterized in that: the raw materials include antioxidant; the antioxidant dosage is 0.05 - 0.5 wt% of the nylon salt.

10. The preparation method of the block copolymerized nylon according to claim 9, characterized in that: the antioxidant is selected from at least one of bis(2,4 - dicumylphenyl)pentaerythritol diphosphite, antioxidant 1790, antioxidant 3114, antioxidant 1010, and antioxidant 1098.

11. The preparation method of the block copolymerized nylon according to claim 1, characterized in that the polycondensation reaction includes: mixing raw materials including at least two kinds of double - end - group nylon oligomers, water, and a molecular weight regulator, heating up and increasing the pressure for reaction; reducing the pressure to atmospheric pressure; and continuing the reaction under atmospheric pressure to obtain the block copolymerized nylon.

12. The preparation method of the block copolymerized nylon according to claim 11, characterized in that: heating up to 180 - 240 °C and increasing the pressure to 1.2 - 2.2 MPa for reaction for 0.2 - 5.0 h; and continuing the reaction for 0.2 - 8.0 h at 180 - 300 °C and atmospheric pressure.

13. The preparation method of the block copolymerized nylon according to claim 11, characterized in that: the molecular weight regulator is at least one of monocarboxylic acid, dicarboxylic acid, monoamine, and diamine.

14. The preparation method of the block copolymerized nylon according to claim 13, characterized in that: the dosage of the molecular weight regulator is 0.05 - 1.0 wt% of the total amount of the nylon oligomers.

15. The block copolymerized nylon obtained by the preparation method according to any one of claims 1 - 14.