Polyamide copolymer with narrow molecular weight distribution and preparation method thereof

Abstract

The present invention discloses a polyamide copolymer with a narrow molecular weight distribution and a preparation method thereof, belonging to the technical field of polyamide copolymer preparation. The method comprises: polymerizing a fatty chain diamine monomer and a fatty chain diacid monomer at 180°C to 220°C for 1 to 3 hours to form a prepolymer; polymerizing the formed prepolymer, alicyclic binary material, a composite additive, and the binary monomer in proportion at 220 to 240°C for 1 to 3 hours, venting the mixture to a pressure below 0.5 MPa, and polymerizing the mixture at a temperature of 260 to 300°C for 1 to 5 hours; venting the mixture, evacuating the mixture, continuing polymerization at 280 to 320°C, crushing the mixture, and drying the mixture to obtain a final polymerized product. The method first reduces the activity of the fatty chain monomer through the reaction of the fatty chain diamine monomer and the fatty chain diacid monomer, making it similar in activity to the alicyclic monomer, thereby facilitating uniform subsequent reactions, reducing the molecular weight distribution, and improving physical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polyamide preparation, in particular to a polyamide copolymer with narrow molecular weight distribution and a preparation method thereof. Background Art

[0002] Because the melting point of high-temperature polyamides containing alicyclic rings can reach 300-350°C, making them difficult to industrially apply, they are often copolymerized with long-chain nylon to lower the melting point. The most common method is to copolymerize an aliphatic chain diamine with an aliphatic chain diacid and an alicyclic diacid. However, alicyclic diacids are often affected by steric effects and have different reactivity than aliphatic chain diacids during polymerization. This can lead to competition during the polymerization process and uneven polymerization. Specifically, this may result in a large amount of fatty chain diacids participating in the polymerization in the early stages, and only after a large amount of aliphatic chain diacids are consumed do alicyclic diacids begin to participate in the polymerization in large quantities. Microscopically, this manifests as a molecular chain containing a high proportion of PA106 segments, while another contains a high proportion of PA10C segments. Macroscopically, it manifests as a blend of two different polymers with a large difference in melting points. This results in the prepared high-temperature resistant polyamide copolymers always having the phenomenon of the diacid ratio in the molecular chain not matching the feed, a wide molecular weight distribution, and multiple peaks in the GPC spectrum, which greatly affects the stability of the polymer, and thus makes the thermal and mechanical properties unstable, seriously hindering its large-scale production and industrial application. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a polyamide copolymer with a narrow molecular weight distribution and a method for preparing the same. The present invention first reduces the activity of the fatty chain-containing monomers by reacting fatty chain diamine monomers with fatty chain diacid monomers, making them more similar in reactivity to alicyclic monomers. This facilitates uniform subsequent reactions, reduces molecular weight distribution, and improves physical properties.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] In one aspect, the present invention provides a method for preparing a polyamide copolymer having a narrow molecular weight distribution, comprising:

[0006] Step 1: According to actual production requirements, weigh a fatty chain diamine monomer, a fatty chain diacid monomer, deionized water, and an alicyclic binary substance; add the fatty chain diacid monomer and deionized water into a reaction kettle, continuously flow nitrogen, raise the temperature to 60-90° C., and stir at a constant temperature to completely dissolve the fatty chain diacid monomer in the water, then raise the temperature to 180-220° C., add the fatty chain diamine monomer, maintain the temperature for 1-3 hours after the addition is completed, and discharge to obtain a prepolymer solid with the same end group as the alicyclic binary substance;

[0007] Wherein, the alicyclic dibasic substance is an alicyclic dicarboxylic acid or an alicyclic diamine;

[0008] When the alicyclic binary substance is an alicyclic dibasic acid having 1 alicyclic ring, the molar ratio of the aliphatic chain diamine monomer to the aliphatic chain diacid monomer is 1:2-3, and the prepolymer solid is a dicarboxyl-terminated prepolymer;

[0009] Alternatively, the alicyclic binary substance contains an alicyclic diamine having 1 alicyclic ring, the molar ratio of the aliphatic chain diamine monomer to the aliphatic chain diacid monomer is 2-3:1, and the prepolymer solid is a diamino-terminated prepolymer;

[0010] Alternatively, the alicyclic dibasic substance contains an alicyclic dibasic acid having 2 alicyclic rings, the molar ratio of the aliphatic chain diamine monomer to the aliphatic chain diacid monomer is 2:3-6, and the prepolymer solid is a dicarboxyl-terminated prepolymer;

[0011] Alternatively, the alicyclic diamine containing two alicyclic rings in the alicyclic diamine substance has two alicyclic rings, the molar ratio of the aliphatic chain diamine monomer to the aliphatic chain diacid monomer is 3-6:2, and the prepolymer solid is a diamino-terminated prepolymer;

[0012] Step 2: Weighing the prepolymer, composite additives and binary monomers prepared in step 1, wherein the amount of the binary monomer is the sum of the molar amounts of the prepolymer and the alicyclic binary substance;

[0013] The prepolymer, the alicyclic binary substance, the composite additive and the binary monomer are polymerized at 220-240° C. for 1-3 hours according to the proportion, the mixture is vented until the pressure is lower than 0.5 MPa, and the temperature reaches 260-300° C. and polymerized for 1-5 hours;

[0014] Wherein, the alicyclic binary substance is an alicyclic dibasic acid, and the binary monomer is the same aliphatic chain diamine as in step 1;

[0015] Alternatively, when the alicyclic binary substance is an alicyclic diamine, the binary monomer is the same aliphatic chain diacid as in step 1;

[0016] Step 3: Expel all gases, apply vacuum, and continue polymerization at 280-320°C. Crushed and dried to obtain the final polymerized product. Preferably, the polymerization time in step 4 is 0.5-2 hours; alternatively, the polymerization time is 5-8 hours. If the polymerization time in this step is 5-8 hours, a product with higher randomness and narrower molecular weight distribution can be obtained through the amidation reaction. However, the product obtained with a polymerization time of 0.5-2 hours already has excellent regularity and a lower molecular weight distribution.

[0017] Furthermore, the fatty chain dibasic acid monomer is a dibasic acid with a carbon chain length of 3 to 18; the fatty chain diamine monomer is a diamine with a carbon chain length of 4 to 18;

[0018] The alicyclic dicarboxylic acid is a para- or meta-substituted hexacyclic dicarboxylic acid, preferably 1,4-cyclohexanedicarboxylic acid (1,4CHDA), 1,4-cyclohexanediacetic acid or 1,3-cyclohexanedicarboxylic acid (1,3CHDA); the alicyclic diamine is a para- or meta-substituted hexacyclic diamine, preferably 1,4-cyclohexanedimethylamine, 1,4-cyclohexanediethylamine (1,4CBMA), 1,3-cyclohexanedimethylamine, 4,4'-diaminodicyclohexylmethane (PACM), 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM) or 4,4'-diaminodicyclohexylpropane (PACP).

[0019] Furthermore, the composite additive comprises an antioxidant, a stabilizer, and a catalyst; the amount of the catalyst is 0.6-1 wt‰ of the total mass of the fatty chain diamine monomer, the fatty chain diacid monomer, the alicyclic binary substance, and the binary monomer; the antioxidant is 1-2 wt‰ of the total mass of the fatty chain diamine monomer, the fatty chain diacid monomer, the alicyclic binary substance, and the binary monomer; and the stabilizer is 0.6-1 wt‰ of the total mass of the fatty chain diamine monomer, the fatty chain diacid monomer, the alicyclic binary substance, and the binary monomer. Preferably, the catalyst is one or more of phosphoric acid, calcium hypophosphite, sodium hypophosphite, antimony trioxide, sodium antimonate, titanium tetrachloride, and tetraethyl titanate; the antioxidant is one or more of antioxidant 1098, antioxidant 1010, antioxidant B215, and antioxidant seed; and the stabilizer is one or more of stabilizer H10, stabilizer 3322, stabilizer ANSEED, and stabilizer N392.

[0020] In the present invention, the molar ratio of acid to amine is the same. If the monomer used is volatile, such as pentamethylenediamine, it should be slightly excessive, with a ratio of 1:1.02 to 1:1.05.

[0021] On the other hand, the present invention also provides a polyamide copolymer prepared by the above method.

[0022] Assume that the alicyclic dicarboxylic acid is A, the aliphatic chain dicarboxylic acid is B, and the aliphatic chain diamine is C. The copolymer prepared this time has a cyclic acid to chain acid ratio of 1:9. Further assuming that 0.1 mol of cyclic acid and 0.9 mol of chain acid are used this time, the ratios of each step are as follows:

[0023] S1: The prepared microblock is BCB, where the total amount of B is set to 0.9 mol and C is half of B, i.e., 0.45 mol. To ensure the formation of BCB, the amount of B used can be excessive. For example, the molar amount of B used here is less than 1.35 mol, but since only 0.45 mol of C is added, the final BCB block prepared is also 0.45 mol. It can be regarded as a new diacid with the following structural formula:

[0024]

[0025] Wherein, m is 1, R1 is a C4-C18 alkyl group, and R2 is C3-C18;

[0026] S2: The diacid units in the system now contain 0.45 mol BCB and 0.1 mol A, totaling 0.55 mol diacid, so 0.55 mol diamine monomer needs to be added. Considering that the diamine may volatilize, 1.02 to 1.05 times the diamine is usually added.

[0027] If the alicyclic diamine is copolymerized with a fatty chain diamine and a fatty chain diacid, the positions of the above-mentioned acid and amine can be switched.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention first controls the amount of monomer addition through the reaction of a fatty chain diamine monomer and a fatty chain diacid monomer to obtain a prepolymer with different repeating units, thereby reducing the reactivity of the fatty chain monomer to make it similar to the reactivity of the alicyclic monomer, facilitating a uniform reaction in the subsequent reaction process, reducing the molecular weight distribution, and improving the physical properties.

[0030] The present invention determines the number of repeating units of the prepolymer according to the structure of the binary substance containing an alicyclic ring, and then ensures the structure of the generated prepolymer by using an excess of one of the aliphatic chain monomers, which can effectively prevent the problem of uneven reaction caused by different monomers. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The DSC diagram of the copolymer prepared in Example 1;

[0032] Figure 2 is the TGA graph of the copolymer prepared in Example 1;

[0033] Figure 3 GPC chart of the copolymer prepared in Example 1;

[0034] Figure 4 This is the GPC chart of the copolymer prepared in Example 2;

[0035] Figure 5 This is the GPC chart of the copolymer prepared in Example 3;

[0036] Figure 6 This is the GPC chart of the copolymer prepared in Example 5;

[0037] Figure 7 This is the GPC chart of the copolymer prepared in Example 6. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0039] In the present invention, the materials and reagents used, unless otherwise specified, can be obtained from commercial sources.

[0040] The present invention provides a polyamide copolymer with narrow molecular weight distribution and a preparation method thereof, and specific embodiments are as follows.

[0041] Example 1 (10C-5:5)

[0042] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0043] S1: Weigh 86 parts by weight of decanediamine, 219 parts by weight of adipic acid, and 122 parts by weight of deionized water, add the adipic acid and deionized water into a glass reactor, continuously flow nitrogen, raise the temperature to 90°C, and stir at this constant temperature for 20 minutes to completely dissolve the adipic acid in the water. Then, raise the temperature to 180°C, slowly add decanediamine, and keep the temperature constant for 2 hours after the addition is completed. Discharge the material to obtain a solid prepolymer, which is then washed with water and ethanol multiple times and dried in an oven at 60°C.

[0044] S2: Weigh 172 parts by weight of 1,4-cyclohexanedicarboxylic acid, 258 parts by weight of decanediamine, 0.66 parts by weight of calcium hypophosphite, 0.66 parts by weight of stabilizer 3322, and 1.32 parts by weight of antioxidant seed, and put them into a high-temperature reactor together with the prepolymer. Turn on the condensation water, start stirring, and polymerize at 230°C for 2 hours. At this time, slowly release the gas, and adjust the heating and exhaust rates by detecting the pressure change and the mass of the discharged water. At the same time, set the program temperature to 300°C. Wait until the pressure drops below 0.5 MPa and the temperature reaches 300°C;

[0045] S3: exhaust the gas and start vacuuming. During this process, the temperature continues to rise to 320°C. The polymerization is continued for 5 hours. The material is discharged, crushed and dried in a vacuum oven for 12 hours to obtain a uniformly polymerized copolymerized polyamide product.

[0046] Depend on Figure 1-3 It can be seen that the melting point of the copolymer prepared in Example 1 is 289.9°C, the onset decomposition temperature is 375.8°C, the maximum thermal decomposition temperature is 457.17°C, the molecular weight distribution is only 1.86, and the relative molecular weight is 16206. The molecular weight distribution of the copolymer prepared in this example is narrow and has only one melting point, which proves that the continuous reading distribution of the copolymer prepared by the present invention is more uniform.

[0047] Example 2 (6C-1:9)

[0048] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0049] S1: Weigh 54 parts by weight of hexamethylenediamine, 131 parts by weight of adipic acid, and 74 parts by weight of deionized water, add the adipic acid and deionized water into a glass reactor, continuously flow nitrogen, raise the temperature to 90°C, and stir at this constant temperature for 10 minutes to completely dissolve the adipic acid in the water. Then, raise the temperature to 180°C, slowly add hexamethylenediamine, and maintain the temperature for 1.5 hours after the addition is complete. Discharge the solid prepolymer, wash it with water and ethanol several times, and dry it in an oven at 60°C.

[0050] S2: Weigh 17 parts by weight of 1,4-cyclohexanedicarboxylic acid, 64 parts by weight of hexamethylenediamine, 0.22 parts by weight of calcium hypophosphite, 0.22 parts by weight of stabilizer 3322, and 0.44 parts by weight of antioxidant 1010, and put them into a high-temperature reactor together with the prepolymer. Turn on the condensation water, start stirring, and polymerize at 220°C for 2 hours. At this time, start to slowly release the gas, and adjust the rate of heating and exhaust by detecting the pressure change and the mass of the discharged water. At the same time, set the program temperature to 260°C. Wait until the pressure drops below 0.5 MPa and the temperature reaches 260°C.

[0051] S3: exhaust the gas and start vacuuming. During this process, the temperature continues to rise to 280°C, and the polymerization is continued for 5 hours. The material is discharged, crushed, and dried in a vacuum oven for 12 hours to obtain a uniformly polymerized copolymerized polyamide product.

[0052] Depend on Figure 4 It can be seen that the copolymer prepared in this example has a weight distribution of 1.98.

[0053] Example 3 (PA46 / 41,4-cyclohexanediacetic acid - 8:2)

[0054] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0055] S1: Weigh 36 parts by weight of butanediamine, 146 parts by weight of adipic acid, and 121 parts by weight of deionized water, add the adipic acid and deionized water into a glass reactor, continuously flow nitrogen, raise the temperature to 90°C, and stir at this constant temperature for 10 minutes to completely dissolve the adipic acid in the water. Then, raise the temperature to 180°C, slowly add butanediamine, and maintain the temperature for 1.5 hours after the addition is complete. Discharge the material to obtain a solid prepolymer, which is then washed with water and ethanol multiple times and dried in an oven at 60°C.

[0056] S2: Weigh 28 parts by weight of 1,4-cyclohexanediacetic acid, 53 parts by weight of hexamethylenediamine, 0.22 parts by weight of calcium hypophosphite, 0.22 parts by weight of stabilizer 3322, and 0.44 parts by weight of antioxidant 1010, and put them into a high-temperature reactor together with the prepolymer. Turn on the condensation water, start stirring, and polymerize at 230°C for 2 hours. At this time, start to slowly release the gas. Adjust the rate of heating and exhaust by detecting the pressure change and the mass of the discharged water. At the same time, set the program temperature to 300°C. Wait until the pressure drops below 0.5 MPa and the temperature reaches 280°C.

[0057] S3: exhaust the gas and start vacuuming. During this process, the temperature continues to rise to 330°C, and the polymerization is continued for 1 hour. The material is discharged, crushed, and dried in a vacuum oven for 12 hours to obtain a uniformly polymerized copolymerized polyamide product.

[0058] Depend on Figure 5 It can be seen that the weight distribution of the copolymer prepared in this example is 2.61.

[0059] Example 4: (PA101, 3CHDA / 1010-6:4)

[0060] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0061] The experimental steps are the same as in Example 1, and the proportions of the reactants added are as follows:

[0062] S1: 81 parts by weight of sebacic acid, 35 parts by weight of decanediamine, and 104 parts by weight of deionized water;

[0063] S2: S1 prepolymer, 103 parts by weight of 1,3-cyclohexanedicarboxylic acid, 138 parts by weight of decanediamine, 0.34 parts by weight of calcium hypophosphite, 0.34 parts by weight of stabilizer 3322, and 0.68 parts by weight of antioxidant 1010.

[0064] Example 5 (PA1,4-cyclohexanediamine 10 / 610-8:2)

[0065] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0066] S1: Weigh 21 parts by weight of sebacic acid, 35 parts by weight of hexamethylenediamine, and 37 parts by weight of deionized water, add the sebacic acid and deionized water to a glass reactor, continuously flow nitrogen, raise the temperature to 90°C, and stir at this constant temperature for 10 minutes to completely dissolve the adipic acid in the water. Then, raise the temperature to 180°C, slowly add hexamethylenediamine, and maintain the temperature for 1 hour after the addition is complete. Discharge the solid prepolymer, wash it with water and ethanol several times, and dry it in an oven at 60°C.

[0067] S2: Weigh 90 parts by weight of 1,4-cyclohexanediamine, 182 parts by weight of dodecanedioic acid, 0.31 parts by weight of calcium hypophosphite, 0.31 parts by weight of stabilizer 3322, and 0.62 parts by weight of antioxidant 1010, and put them into a high-temperature reactor together with the prepolymer. Turn on the condensation water, start stirring, and polymerize at 220°C for 2 hours. At this time, start to slowly release the gas. Adjust the rate of heating and exhaust by detecting the pressure change and the mass of the discharged water. At the same time, set the program temperature to 280°C. Wait until the pressure drops below 0.5 MPa and the temperature reaches 280°C.

[0068] S3: exhaust the gas, start vacuuming, continue to increase the temperature to 320 ° C, polymerize for 1 hour, discharge the material, crush it and dry it in a vacuum oven for 12 hours to obtain a uniformly polymerized copolymerized polyamide product.

[0069] Depend on Figure 6 It can be seen that the copolymer prepared in this example has a weight distribution of 2.67.

[0070] Example 6: (PA1,3-cyclohexanedimethylamine 6 / 106-5:5)

[0071] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0072] The experimental steps are the same as in Example 1, and the proportions of the reactants added are as follows:

[0073] S1: 36.5 parts by weight of adipic acid, 103 parts by weight of decanediamine, and 94 parts by weight of deionized water;

[0074] S2: S1 prepolymer, 71 parts by weight of 1,3-cyclohexanedimethylamine, 110 parts by weight of adipic acid, 0.29 parts by weight of calcium hypophosphite, 0.29 parts by weight of stabilizer 3322, and 0.58 parts by weight of antioxidant 1010.

[0075] Depend on Figure 7 It can be seen that the copolymer prepared in this example has a weight distribution of 2.52.

[0076] Example 7: (PA1, 4CBMA6 / 66-9:1)

[0077] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0078] The experimental steps are the same as those in Example 5, and the proportions of the added amounts of the reactants are as follows:

[0079] S1: 36.5 parts by weight of adipic acid, 8 parts by weight of hexamethylenediamine, and 29 parts by weight of deionized water;

[0080] S2: S1 prepolymer, 157 parts by weight of 1,4-cyclohexanediethylamine, 144 parts by weight of adipic acid, 0.33 parts by weight of calcium hypophosphite, 0.33 parts by weight of stabilizer 3322, and 0.66 parts by weight of antioxidant 1010.

[0081] Example 8 (PA612 / PACM12-2:8)

[0082] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0083] S1: Weigh 23 parts by weight of dodecanedioic acid, 35 parts by weight of hexamethylenediamine, and 38 parts by weight of deionized water, add the dodecanedioic acid and deionized water into a glass reactor, continuously flow nitrogen, raise the temperature to 90°C, and stir at this constant temperature for 10 minutes to completely dissolve the adipic acid in the water. Then, raise the temperature to 180°C, slowly add hexamethylenediamine, and maintain the temperature for 1 hour after the addition is complete. Discharge the solid prepolymer, wash it with water and ethanol several times, and dry it in an oven at 60°C.

[0084] S2: Weigh 168 parts by weight of PACM, 207 parts by weight of dodecanedioic acid, 0.28 parts by weight of calcium hypophosphite, 0.28 parts by weight of stabilizer 3322, and 0.56 parts by weight of antioxidant 1010, and put them into a high-temperature reactor together with the prepolymer. Turn on the condensation water, start stirring, and polymerize at 200°C for 2 hours. At this time, slowly release the gas, and adjust the rate of heating and exhaust by detecting the pressure change and the mass of the discharged water. At the same time, set the program temperature to 230°C. Wait until the pressure drops below 0.5 MPa and the temperature reaches 230°C.

[0085] S3: exhaust the gas, start vacuuming, continue polymerization for 3 hours, discharge the material, crush it and dry it in a vacuum oven for 12 hours to obtain a transparent copolymerized polyamide product.

[0086] Example 9: (PA MACM18 / 618-4:6)

[0087] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0088] The experimental steps are the same as those in Example 8, and the proportions of the reactants added are as follows:

[0089] S1: Weigh 126 parts by weight of octadecanedioic acid, 70 parts by weight of hexamethylenediamine, and 130 parts by weight of deionized water;

[0090] S2: Weigh 84 parts by weight of MACM, 189 parts by weight of octadecane dioic acid, 0.47 parts by weight of calcium hypophosphite, 0.47 parts by weight of stabilizer 3322, and 0.93 parts by weight of antioxidant 1010.

[0091] Example 10: (PA PACP16 / 1016-3:7)

[0092] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0093] The experimental steps are the same as those in Example 8, and the proportions of the reactants added are as follows:

[0094] S1: Weigh 134 parts by weight of hexadecanedioic acid, 121 parts by weight of decanediamine, and 103 parts by weight of deionized water.

[0095] S2: Weigh 43 parts by weight of PACP, 152 parts by weight of hexadecanedioic acid, 0.35 parts by weight of calcium hypophosphite, 0.35 parts by weight of stabilizer 3322, and 0.7 parts by weight of antioxidant 1010.

[0096] In order to further illustrate the beneficial effects of the present invention, the following comparative examples are constructed.

[0097] Comparative Example 1 (10C-5:5)

[0098] A method for preparing a polyamide copolymer comprises:

[0099] S1: Weigh 172 parts by weight of decanediamine, 86 parts by weight of 1,4-cyclohexanedicarboxylic acid, 73 parts by weight of adipic acid, 220 parts by weight of deionized water, and a composite additive consisting of 0.22 parts by weight of calcium hypophosphite, 0.22 parts by weight of stabilizer 3322, and 0.44 parts by weight of antioxidant seed. Stir well and put into a high-temperature reactor. Turn on the condenser water and heating. Keep the temperature at 90°C for 60 minutes, then raise the temperature to 220°C and keep the temperature at this temperature for 2 hours.

[0100] S2: Set the program to 300℃, slowly release the gas, and gradually increase the temperature. When the temperature reaches 300 degrees, the pressure drops to below 0.5MPa, evacuate the gas, vacuumize, and continue polymerization for 1 hour. Discharge the material, crush it, and dry it in a vacuum oven for 12 hours to obtain a conventionally polymerized copolyamide product.

[0101] Comparative Example 2

[0102] A method for preparing a polyamide copolymer comprises:

[0103] S1: Weigh 173 parts by weight of hexamethylenediamine, 26 parts by weight of 1,4-cyclohexanedicarboxylic acid, 197 parts by weight of adipic acid, 264 parts by weight of deionized water, and a composite additive consisting of 0.4 parts by weight of calcium hypophosphite, 0.4 parts by weight of stabilizer 3322, and 1.19 parts by weight of antioxidant 1010. After stirring evenly, put them into a high-temperature reactor, turn on the condenser water, turn on the heating, keep the temperature at 90°C for 60 minutes, then raise the temperature to 220°C and keep the temperature at that for 4 hours.

[0104] S2: Set the program to 260°C, slowly release the gas, and gradually increase the temperature. When the temperature reaches 260°C and the pressure drops below 0.5 MPa, evacuate the gas, apply vacuum, and continue polymerization for 2 hours. Discharge the material, crush it, and dry it in a vacuum oven for 12 hours to obtain a conventionally polymerized copolyamide product.

[0105] Comparative Example 3

[0106] A method for preparing a polyamide copolymer comprises:

[0107] S1: Weigh 172 parts by weight of decanediamine, 219 parts by weight of adipic acid, and 122 parts by weight of deionized water, add the adipic acid and deionized water into a glass reactor, continuously flow nitrogen, raise the temperature to 90°C, and stir at this constant temperature for 20 minutes to completely dissolve the adipic acid in the water. Then, raise the temperature to 180°C, slowly add decanediamine, and maintain the temperature for 2 hours after the addition is completed. Discharge the material to obtain a prepolymer.

[0108] S2: Weigh 258 parts by weight of 1,4-cyclohexanedicarboxylic acid, 344 parts by weight of decanediamine, 0.99 parts by weight of calcium hypophosphite, 0.99 parts by weight of stabilizer 3322, and 1.98 parts by weight of antioxidant seed, and put them into a high-temperature reactor together with the prepolymer. Turn on the condensation water, start stirring, and polymerize at 230°C for 2 hours. At this time, slowly release the gas, and adjust the heating and exhaust rates by detecting the pressure change and the mass of the discharged water. At the same time, set the program temperature to 300°C. Wait until the pressure drops below 0.5 MPa and the temperature reaches 300°C;

[0109] S3: exhaust the gas and start vacuuming. During this process, the temperature continues to rise to 320°C. The polymerization is continued for 5 hours. The material is discharged, crushed and dried in a vacuum oven for 12 hours to obtain a uniformly polymerized copolymerized polyamide product.

[0110] Comparative Example 4

[0111] A method for preparing a polyamide copolymer comprises:

[0112] S1: Weigh 155 parts by weight of decanediamine, 175 parts by weight of adipic acid, and 122 parts by weight of deionized water, add the adipic acid and deionized water into a glass reactor, continuously flow nitrogen, raise the temperature to 90°C, and stir at this constant temperature for 20 minutes to completely dissolve the adipic acid in the water. Then, raise the temperature to 180°C, slowly add decanediamine, maintain the constant temperature for 2 hours after the addition is completed, and discharge the material to obtain a prepolymer.

[0113] S2: Weigh 206 parts by weight of 1,4-cyclohexanedicarboxylic acid, 258 parts by weight of decanediamine, 0.79 parts by weight of calcium hypophosphite, 0.79 parts by weight of stabilizer 3322, and 1.58 parts by weight of antioxidant seed, and put them into a high-temperature reactor together with the prepolymer. Turn on the condensation water, start stirring, and polymerize at 230°C for 2 hours. At this time, slowly release the gas, and adjust the heating and exhaust rates by detecting the pressure change and the mass of the discharged water. At the same time, set the program temperature to 300°C. Wait until the pressure drops below 0.5 MPa and the temperature reaches 300°C;

[0114] S3: exhaust the gas and start vacuuming. During this process, the temperature continues to rise to 320°C. The polymerization is continued for 5 hours. The material is discharged, crushed and dried in a vacuum oven for 12 hours to obtain a uniformly polymerized copolymerized polyamide product.

[0115] Comparative Example 5

[0116] A method for preparing a polyamide copolymer with a narrow molecular weight distribution comprises:

[0117] S1: Weigh 172 parts by weight of 1,4-cyclohexanedicarboxylic acid, 258 parts by weight of decanediamine, and 122 parts by weight of deionized water, add the adipic acid and deionized water into a glass reactor, continuously flow nitrogen, raise the temperature to 90°C, and stir at this constant temperature for 20 minutes to completely dissolve the adipic acid in the water. Then, raise the temperature to 180°C, slowly add decanediamine, and maintain the temperature for 2 hours after the addition is completed. Discharge the material to obtain a prepolymer.

[0118] S2: 86 parts by weight of decanediamine, 219 parts by weight of adipic acid, 0.66 parts by weight of calcium hypophosphite, 0.66 parts by weight of stabilizer 3322, and 1.32 parts by weight of antioxidant seed were weighed and placed into a high-temperature reactor together with the prepolymer. The condenser water was turned on, stirring was started, and polymerization was carried out at 230°C for 2 hours. At this time, slow gas release was started. The heating and gas release rates were adjusted by detecting the pressure change and the mass of the discharged water. At the same time, the program temperature was set to 300°C. When the pressure dropped below 0.5 MPa and the temperature reached 300°C;

[0119] S3: exhaust the gas and start vacuuming. During this process, the temperature continues to rise to 320°C. The polymerization is continued for 5 hours. The material is discharged, crushed and dried in a vacuum oven for 12 hours to obtain a uniformly polymerized copolymerized polyamide product.

[0120] The copolymers prepared in Examples 1-10 and Comparative Examples 1-5 were subjected to performance testing using the following testing methods. The test results are shown in Table 1-2.

[0121] Relative viscosity test: using m-cresol as the standard solvent, dissolve 0.25 g of sample in 25 ml of m-cresol, shake well, and measure the relative viscosity using an Ubbelohde viscometer.

[0122] Gel Permeation Chromatography (GPC): Dissolve 3-5 mg of sample in 1-2 ml of hexafluoroisopropanol and shake thoroughly before testing. The mobile phase is hexafluoroisopropanol at a flow rate of 1 ml / min, and the standard is polymethyl methacrylate (PMMA).

[0123] Thermogravimetric analysis (TG): Weigh at least 10 mg of sample, test at a temperature of 25-600°C at a heating rate of 10°C / min, under nitrogen protection, and obtain a curve of sample mass change during the heating process.

[0124] Differential Scanning Calorimetry (DSC): Prepare a sample of less than 10 mg in an aluminum crucible. The test temperature program is: 30°C to 350 / 400°C, heating rate 20°C / min, 350 / 400°C to 30°C, cooling rate 20°C / min, and after eliminating the thermal history, the temperature is raised again to 30°C to 350 / 400°C at a heating rate of 10°C / min. The melting point and crystallization temperature of the product are tested.

[0125] Table 1

[0126]

[0127] As can be seen from Table 1, in Examples 1-4, the alicyclic dibasic acid containing an alicyclic binary substance with an alicyclic ring number of 1 is used, and the molar ratio of the alicyclic diamine monomer to the alicyclic diacid monomer is regulated to obtain a prepolymer having a dicarboxyl-terminated repeating unit of 1. Then, the prepolymer and the alicyclic dibasic acid are reacted simultaneously with the alicyclic diamine. Since the prepolymer, the alicyclic dibasic acid and the alicyclic diamine have comparable reactivity, a copolymer with uniform segment distribution can be obtained, with a molecular weight distribution of 1.86-2.35 and a relatively narrow molecular weight distribution, which also proves that the prepared copolymer is relatively uniform. In Examples 5-7, the alicyclic diamine containing an alicyclic binary substance with an alicyclic ring number of 1 also has a narrow molecular weight distribution of the obtained copolymer. In Examples 8-10, the alicyclic diamine containing an alicyclic binary substance with an alicyclic ring number of 2 has a molecular weight distribution of 2.18-2.39.

[0128] The copolymers prepared in Examples 1-7 of the present invention exhibited a single melting point, demonstrating relatively uniform copolymer segments and high tensile strength. In Examples 8-10, the alicyclic binary substances, due to their two alicyclic rings, exhibited significant steric hindrance, hindering crystallization. Consequently, the resulting copolymers exhibited no melting point. However, the resulting copolymers exhibited high light transmittance (92% for Example 8, 90% for Example 9, and 75% for Example 10), while also exhibiting excellent mechanical properties.

[0129] Table 2

[0130]

[0131] As can be seen from Table 2, in Comparative Examples 1 and 2, all monomers were added to the reactor at one time, and the resulting copolymer had two melting points, a molecular weight distribution of 10-12.47, and the tensile strength of the prepared copolymer was also low; in Comparative Examples 3-4, the substances were the same as in Example 1, but the molar ratio of decanediamine and adipic acid was adjusted so that the repeating unit of the prepared prepolymer was 2 or 3, and the molecular weight distribution of the obtained copolymer was also relatively wide, and the copolymer had two melting points or a melting point with a wide tolerance, and the mechanical properties were also greatly reduced; this is because the reactivity of the prepolymers of different repeating units is different from that of 1,4-cyclohexanedicarboxylic acid. During the reaction of both with decanediamine at the same time, the different reactivity caused some chain segments to be unevenly distributed, resulting in a wide molecular weight distribution of the prepared copolymer and reduced mechanical properties.

[0132] In Comparative Example 5, 1,4-cyclohexanedicarboxylic acid is first reacted with decanediamine to obtain a prepolymer, which is then mixed with adipic acid and reacted with decanediamine simultaneously. Due to the serious mismatch between the reactivity of the prepolymer and the reactivity of adipic acid, the prepared copolymer has a wide molecular weight distribution and poor mechanical properties.

[0133] In summary, the present invention regulates the molar amounts of the fatty chain diamine monomer and the fatty chain diacid monomer based on the number of alicyclic rings in the alicyclic binary substance, so that the reactivity of the prepared prepolymer is equivalent to that of the alicyclic binary substance, which facilitates the subsequent reaction process, enables the reaction to proceed uniformly, reduces the molecular weight distribution, and improves the physical properties.

[0134] The above is a preferred embodiment of the present invention. For ordinary technicians in this technical field, making several improvements and modifications without departing from the principles of the present invention should also be considered as the scope of protection of the present invention.

Claims

1. A method for preparing a polyamide copolymer with a narrow molecular weight distribution, characterized in that: include: Step 1: Weighing a fatty chain diamine monomer, a fatty chain diacid monomer, deionized water, and an alicyclic binary substance; adding the fatty chain diacid monomer and deionized water into a reaction kettle, continuously flowing nitrogen, heating to 60-90° C., stirring at a constant temperature to completely dissolve the fatty chain diacid monomer in the water, then heating to 180-220° C., adding the fatty chain diamine monomer, and maintaining the temperature for 1-3 hours after the addition is completed, to obtain a prepolymer solid with the same end group as the alicyclic binary substance; Wherein, the alicyclic dibasic substance is an alicyclic dicarboxylic acid or an alicyclic diamine; When the alicyclic binary substance is an alicyclic dibasic acid having 1 alicyclic ring, the molar ratio of the aliphatic chain diamine monomer to the aliphatic chain diacid monomer is 1:2-3, and the prepolymer solid is a dicarboxyl-terminated prepolymer; Alternatively, the alicyclic binary substance contains an alicyclic diamine having 1 alicyclic ring, the molar ratio of the aliphatic chain diamine monomer to the aliphatic chain diacid monomer is 2-3:1, and the prepolymer solid is a diamino-terminated prepolymer; Alternatively, the alicyclic dibasic substance contains an alicyclic dibasic acid having 2 alicyclic rings, the molar ratio of the aliphatic chain diamine monomer to the aliphatic chain diacid monomer is 2:3-6, and the prepolymer solid is a dicarboxyl-terminated prepolymer; Alternatively, the alicyclic diamine containing two alicyclic rings in the alicyclic diamine substance has two alicyclic rings, the molar ratio of the aliphatic chain diamine monomer to the aliphatic chain diacid monomer is 3-6:2, and the prepolymer solid is a diamino-terminated prepolymer; Step 2: Weigh the prepolymer, composite additive, and binary monomer prepared in step 1, where the amount of the binary monomer is the sum of the molar amounts of the prepolymer and the alicyclic binary substance; polymerize the prepolymer, alicyclic binary substance, composite additive, and binary monomer according to a certain proportion at 220-240° C. for 1-3 hours, exhaust until the pressure is lower than 0.5 MPa, and polymerize at a temperature of 260-300° C. for 1-5 hours; Wherein, the alicyclic binary substance is an alicyclic dibasic acid, and the binary monomer is the same aliphatic chain diamine as in step 1; Alternatively, when the alicyclic binary substance is an alicyclic diamine, the binary monomer is the same aliphatic chain diacid as in step 1; Step 3: exhaust the gas, evacuate the mixture, continue polymerization at 280-320°C, crush and dry the mixture to obtain the final polymerization product.

2. The preparation method according to claim 1, characterized in that The polymerization time in step 3 is 0.5 to 2 hours; or the polymerization time is 5 to 8 hours.

3. The preparation method according to claim 2, characterized in that In step 1, the fatty chain dibasic acid monomer is a dibasic acid with a carbon chain length of 3 to 18; the fatty chain diamine monomer is a diamine with a carbon chain length of 4 to 18; The alicyclic dicarboxylic acid is a para- or meta-substituted hexacyclic dicarboxylic acid; the alicyclic diamine is a para- or meta-substituted hexacyclic diamine.

4. The preparation method according to claim 3, characterized in that The alicyclic dicarboxylic acid is 1,4-cyclohexanedicarboxylic acid (1,4CHDA), 1,4-cyclohexanediacetic acid or 1,3-cyclohexanedicarboxylic acid (1,3CHDA); The alicyclic diamine is 1,4-cyclohexanedimethylamine, 1,4-cyclohexanediethylamine (1,4CBMA), 1,3-cyclohexanedimethylamine, 4,4'-diaminodicyclohexylmethane (PACM), 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM) or 4,4'-diaminodicyclohexylpropane (PACP).

5. The preparation method according to claim 2, characterized in that In step 1, the composite additive comprises an antioxidant, a stabilizer and a catalyst; The amount of the catalyst is 0.6-1 wt‰ of the total mass of the fatty chain diamine monomer, the fatty chain diacid monomer, the alicyclic binary substance and the binary monomer; the amount of the antioxidant is 1-2 wt‰ of the total mass of the fatty chain diamine monomer, the fatty chain diacid monomer, the alicyclic binary substance and the binary monomer; and the amount of the stabilizer is 0.6-1 wt‰ of the total mass of the fatty chain diamine monomer, the fatty chain diacid monomer, the alicyclic binary substance and the binary monomer.

6. The preparation method according to claim 5, characterized in that The catalyst is one or more of phosphoric acid, calcium hypophosphite, sodium hypophosphite, antimony trioxide, sodium antimonate, titanium tetrachloride, and tetraethyl titanate.

7. The preparation method according to claim 5, characterized in that The antioxidant is one or more of antioxidant 1098, antioxidant 1010, antioxidant B215, and antioxidant seed.

8. The preparation method according to claim 5, characterized in that The stabilizer is one or more of stabilizer H10, stabilizer 3322, stabilizer ANSEED, and stabilizer N392.

9. The polyamide copolymer prepared by the method according to any one of claims 1 to 8.

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