Cationic polyester and preparation method thereof

Abstract

The invention belongs to the technical field of polyester preparation, and relates to cationic polyester and a preparation method thereof. The cationic polyester is prepared by reacting dibasic acid, aliphatic dihydric alcohol, polyether glycol and metal dicarboxylate with a specific structure. The preparation method comprises the following steps: sequentially carrying out esterification reaction and polycondensation reaction on the reaction raw materials to obtain the cationic polyester. Metal dicarboxylate is used for replacing traditional sulfonate, polyether glycol is combined, group aggregation is avoided through cooperation of metal dicarboxylate and polyether glycol, viscosity rising is buffered, the implosion problem is solved, and cation dyeability is reserved.

Description

Technical Field

[0001] This invention belongs to the field of polyester preparation technology, and relates to a cationic polyester and its preparation method. Background Technology

[0002] Polyester materials are widely used in fiber, packaging, and engineering plastics due to their excellent mechanical properties, chemical stability, and processability. Among them, cationic dyeable polyester (CDP, commonly known as cationic polyester) improves dyeing performance by introducing ionic groups, meeting the textile industry's demand for diverse fiber colors and becoming an important direction for polyester modification.

[0003] Currently, existing technologies, such as patent application CN115161801A, generally use sodium isophthalate sulfonate (SIPA) or its dimethyl ester (SIPM) as cationic modifying monomers, introducing sodium sulfonate groups into the polyester backbone through copolymerization with diacids and diols. However, this technical route has significant drawbacks: the sodium sulfonate groups are highly polar and easily form local aggregates in the molecular chain, leading to a sharp increase in melt viscosity during the high-vacuum polycondensation stage. When the polycondensation reaction proceeds to a certain extent, the melt fluidity drops sharply, easily resulting in polymer "climbing the rod," excessive gel content, or even "explosive polymerization" phenomena such as stirrer seizure, seriously affecting production stability. At the same time, the chips produced by explosive polymerization, due to uneven molecular weight distribution and numerous gel particles, frequently cause problems such as filter component blockage and fiber breakage during subsequent spinning processes, significantly reducing spinning efficiency and finished fiber quality.

[0004] To alleviate the above problems, existing technologies mostly attempt to adjust the amount of SIPA or optimize the polycondensation process parameters: reducing the amount of SIPA can reduce the risk of explosive polymerization, but it will lead to a significant decrease in the dyeing performance of cationic polyester, making it difficult to balance practicality; adjusting process parameters such as temperature and pressure is limited by equipment and can only slightly improve melt flowability, but cannot fundamentally solve the problem of sudden viscosity increase caused by the aggregation of polar groups, and the overall effect is limited.

[0005] In addition, traditional cationic polyesters have strong melt rigidity. Even if explosive polymerization does not occur, the viscosity rise rate during polycondensation is still relatively fast, resulting in short high-vacuum polycondensation time and poor reaction controllability. At the same time, rigid molecular chains are prone to breakage due to stress concentration during spinning, which further limits their application in high-end textile fields. Summary of the Invention

[0006] The purpose of this invention is to solve the problems existing in the prior art and to provide a cationic polyester and its preparation method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A cationic polyester is prepared by reacting a diacid, an aliphatic diol, a polyether diol, and a metal dicarboxylate. The mass of the metal dicarboxylate is less than 10% of the mass of the diacid. If the amount of metal dicarboxylate is too high, there is still a risk of explosive polymerization.

[0009] The structural formula of the metal dicarboxylate is: HOOC-R1-COO-M 2+ -COO-R2-COOH, where -R1- and -R2- are both chain segments composed of carbon and hydrogen atoms, and the number of carbon atoms in -R1- and -R2- is 1-8. The number of carbon atoms in -R1- and -R2- may be the same or different. M 2+ It can be Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ra²⁺, Fe²⁺, Zn²⁺, or Co²⁺.

[0010] As a preferred technical solution:

[0011] In the cationic polyester described above, the mass of the metal dicarboxylate is more than 0.5% of the mass of the dicarboxylic acid. If the amount of metal dicarboxylate is too low, the improvement in dyeability will be limited.

[0012] As described above, in a cationic polyester, HOOC-R1-COO- and -COO-R2-COOH are oxalic acid segments, malonic acid segments, succinic acid segments, glutaric acid segments, adipic acid segments, heptanoic acid segments, octanoic acid segments, cyclohexanedicarboxylic acid segments, terephthalic acid segments, isophthalic acid segments, or phthalic acid segments.

[0013] As described above, the metal dicarboxylate is magnesium dimalonate, zinc dimalonate, calcium dimalonate, magnesium disuccinate, calcium disuccinate, zinc disuccinate, magnesium adipate, calcium adipate, zinc adipate, calcium isophthalate, zinc isophthalate, magnesium isophthalate, calcium terephthalate, magnesium terephthalate, or zinc terephthalate.

[0014] In the cationic polyester described above, the dicarboxylic acid is terephthalic acid, isophthalic acid, succinic acid, or adipic acid; the aliphatic diol is ethylene glycol, 1,3-propanediol, 1,4-butanediol, or neopentyl glycol; and the polyether diol is polyethylene glycol, polytetrahydrofuran ether diol, polypropylene oxide diol, or polyethylene oxide-propylene oxide copolymer diol.

[0015] As described above, the molecular weight of the cationic polyester is 1000-5000 g / mol for polyethylene glycol, 600-2000 g / mol for polytetrahydrofuran ether diol, 1000-2000 g / mol for polypropylene oxide diol, and 1000-2000 g / mol for polyethylene oxide-propylene oxide copolymer diol.

[0016] As described above, the molar ratio of aliphatic diol to diacid is 1.1-2.2:1; the amount of polyether diol added is 5-60% of the theoretical yield of the cationic polyester.

[0017] The present invention also provides a method for preparing a cationic polyester as described in any of the preceding claims, wherein a diacid, an aliphatic diol, a polyether diol and a metal dicarboxylate are used as reactants, and esterification and polycondensation reactions are carried out sequentially to obtain a cationic polyester.

[0018] As a preferred technical solution:

[0019] As described above, a catalyst is added before the esterification reaction. The catalyst is one or more of antimony trioxide, antimony glycolate, germanium dioxide, tetrabutyl titanate, and tetraisopropyl titanate. The amount of catalyst used is 50-1000 ppm of the theoretical yield of cationic polyester. After the esterification reaction and before the polycondensation reaction, a stabilizer is added. The stabilizer is one or more of triphenyl phosphate, tributyl phosphate, triphenyl phosphite, antioxidant 1010, and antioxidant 245. The amount of stabilizer used is 50-3000 ppm of the theoretical yield of cationic polyester.

[0020] The specific steps of the method described above are as follows:

[0021] (a) After mixing the dicarboxylic acid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification under nitrogen or inert atmosphere at a temperature of 190-270℃ and a pressure of 0-0.5MPa until the esterification rate reaches 95%. Then the pressure is released to atmospheric pressure to end the esterification process.

[0022] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 230-290℃ and an absolute pressure of ≤100Pa. The polycondensation reaction is carried out for more than 110 minutes to obtain cationic polyester.

[0023] The principle of this invention is as follows:

[0024] Existing technologies have not thoroughly analyzed the essence of the process problems caused by sodium sulfonate groups. Through systematic investigation, this invention has found that: due to their extremely high polarity, sodium sulfonate groups are prone to local aggregation in the molecular side chain region through strong electrostatic attraction, forming ion clusters (i.e., stable structural units formed by the aggregation of multiple ions through electrostatic interaction); these ion clusters are the core inducing factors that cause a sharp increase in melt viscosity during the polycondensation process and trigger explosive polymerization.

[0025] In high-vacuum polycondensation reactions, the influence mechanism of ion clusters on melt viscosity is manifested in the following ways: First, as dynamic physical cross-linking points, ion clusters firmly fix the ionic groups on the molecular chains through electrostatic attraction, forming local rigid constraint regions that restrict the rotation and translation of molecular chain segments. This forces the molecular chains to overcome higher energy barriers to undergo conformational changes, directly reducing melt fluidity. Second, multiple ion clusters can further induce the formation of multi-chain entanglement networks, complicating the molecular chain topology and significantly increasing the resistance to molecular chain slippage and untangling, further hindering fluid flow. Thirdly, the shearing and stretching during the polycondensation process disrupts the dynamic equilibrium of "depolymerization-recombination" of ion clusters, causing the cluster structure to continuously increase and combine with molecular chains to form a large number of "ion cluster-molecular chain complexes," significantly increasing energy dissipation and flow resistance. This ultimately leads to a sharp increase in melt viscosity, resulting in polymer climbing, excessive gel content, and in severe cases, stirrer seizure (i.e., "explosive polymerization"). Furthermore, the polyester chips after explosive polymerization, due to uneven molecular weight distribution and the presence of a large number of gel particles, are prone to clogging filter components and causing filament breakage during subsequent spinning, affecting production efficiency and product quality.

[0026] The metal dicarboxylate selected in this invention forms a salt with a metal cation and a carboxyl group. The ionic groups are dispersed in the molecular chain through the stable combination of metal ions and carboxyl groups, avoiding the strong polar aggregation of traditional sulfonate groups. The dispersing effect of the ionic groups of the metal dicarboxylate and the melt structure regulation effect of the polyether diol work synergistically: the metal dicarboxylate reduces polar aggregation to lower viscosity fluctuations, while the polyether diol further buffers the viscosity increase trend through its flexible chain. Together, they ensure the stability and controllability of the polycondensation process, while retaining the cationic stainability of the metal dicarboxylate.

[0027] Beneficial effects:

[0028] This invention uses metal dicarboxylate to replace traditional sulfonate-based cationic modified monomers. Its ionic groups can be dispersed in the molecular chain through the stable combination of metal ions and carboxyl groups, avoiding the local aggregation of traditional sulfonate groups in the side chain region. At the same time, combined with the flexible chain of polyether diol, the two work together to reduce polar aggregation to reduce viscosity fluctuations and further buffer the viscosity increase trend. This effectively solves the problem of explosive polymerization caused by the sudden increase in melt viscosity during high vacuum polycondensation, ensuring that the polycondensation process is stable and controllable, while retaining the cationic stainability brought by metal dicarboxylate. Attached Figure Description

[0029] Figure 1 This is the 1H NMR spectrum of the cationic polyester of Example 8 of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0031] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0032] Polycondensation reaction time: When the polycondensation temperature reaches the process set temperature and the absolute pressure inside the polymerization reactor is ≤100Pa, start timing; set the stirring speed to 40rpm, and stop timing when the stirring power display reaches the set value (300W). This time period is the polycondensation reaction time.

[0033] Number of fiber breaks during melt spinning: Using a spinning machine (Abe Corporation, Japan, ABE Φ25×2 type), the spinning temperature (290℃) was set according to the specific finished product requirements, the winding speed was fixed at 800m / min, and the other process parameters were referenced to the conventional polyester spinning conditions. The sample to be tested was melt spun and run stably, and the number of fiber breaks per hour was counted.

[0034] Example 1

[0035] A method for preparing a cationic polyester, comprising the following specific steps:

[0036] (1) Preparation of materials;

[0037] Dicarboxylic acid: terephthalic acid;

[0038] Aliphatic diols: Ethylene glycol;

[0039] Polyether diol: polyethylene glycol, with a molecular weight of 1000 g / mol;

[0040] Metal dicarboxylate: Zinc diisophthalate;

[0041] Catalyst: Antimony glycol;

[0042] Stabilizer: Triphenyl phosphate;

[0043] (2) Preparation of cationic polyester;

[0044] (a) After mixing the dicarboxylic acid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification reaction at 240°C and 0.2 MPa under nitrogen or inert atmosphere (with stirring at 40 rpm) until the esterification rate reaches 95%. Then the pressure is released to atmospheric pressure to end the esterification.

[0045] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 280°C and an absolute pressure of ≤100Pa, and then polycondensation reaction is carried out for 110 minutes to obtain cationic polyester.

[0046] In steps (a) to (b), the mass of the metal dicarboxylate is 1 / 10 of the mass of the diacid, the molar ratio of the aliphatic diol to the diacid is 1.5:1, the amount of polyether diol added is 6.5% of the theoretical yield of cationic polyester, the amount of catalyst used is 250 ppm of the theoretical yield of cationic polyester, and the amount of stabilizer used is 300 ppm of the theoretical yield of cationic polyester.

[0047] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0048] Comparative Example 1

[0049] A method for preparing a cationic polyester differs from Example 1 in that: no polyether diol is added, the metal dicarboxylate is replaced with sodium isophthalate sulfonate, the mass of sodium isophthalate sulfonate is 1 / 40 of the mass of the dicarboxylic acid, and the polycondensation reaction time is 75 min.

[0050] Tests showed that the final cationic polyester had a breakage rate of 7 times per hour during melt spinning.

[0051] Compared with Example 1, it can be seen that even though the amount of sodium isophthalate sulfonate added in Comparative Example 1 is much lower than that added in Example 1 (zinc isophthalate), the polycondensation reaction time is still significantly shortened, and the number of breakages in the melt-spun cationic polyester is significantly increased, resulting in significantly poorer spinnability. This is because the sodium sulfonate group of sodium isophthalate sulfonate is extremely polar and easily forms local ion clusters on the side chains of the molecular chain, causing molecular chain entanglement and significantly increasing the melt viscosity, resulting in the polycondensation reaction quickly reaching the stirring power threshold and shortening the reaction time. At the same time, the gel particles induced by the ion clusters and the uneven molecular weight distribution make the filter components easy to clog and the fibers easy to break during spinning, resulting in a significant increase in the number of breakages.

[0052] Comparative Example 2

[0053] A method for preparing a cationic polyester differs from Example 1 in that: no polyether diol is added, and the metal dicarboxylate is replaced with sodium isophthalate sulfonate; the polycondensation reaction time is 45 min.

[0054] Tests showed that the final cationic polyester had a breakage rate of 17 times per hour during melt spinning.

[0055] Compared with Example 1, Comparative Example 2 showed a significantly shorter polycondensation reaction time and a significantly worse spinnability of the cationic polyester. This is because Comparative Example 2 did not add polyether diol and used sodium isophthalate sulfonate: on the one hand, the strong polar aggregation effect of sodium sulfonate groups was not suppressed, ion clusters formed and expanded rapidly, accelerating the entanglement of molecular chain networks, and the melt viscosity increased sharply, causing the polycondensation reaction to reach the power limit faster; on the other hand, the lack of polyether diol to regulate the melt structure increased the rigidity of the molecular chain, aggravated the stress concentration problem during spinning, and significantly increased the frequency of fiber breakage.

[0056] Comparative Example 3

[0057] A method for preparing cationic polyester differs from Example 1 in that: the metal dicarboxylate is replaced with sodium isophthalate sulfonate, the amount of polyether diol added is 25.1% of the theoretical yield of cationic polyester, and the polycondensation reaction time is 75 min.

[0058] Tests showed that the final cationic polyester had a breakage rate of 3 times per hour during melt spinning.

[0059] Compared with Example 1, Comparative Example 3 showed a significantly shorter polycondensation reaction time and a significantly worse spinnability of the cationic polyester. This is because the sodium sulfonate groups of sodium isophthalate sulfonate are prone to forming ionic clusters. These ionic clusters, acting as physical crosslinking points, restrict the movement of molecular chains. Their aggregation effect exceeds the viscosity buffering capacity of the polyether diol, resulting in a shorter polycondensation reaction time. At the same time, the molecular weight inhomogeneity and gel particles caused by the ionic clusters were not completely eliminated, and the problem of yarn breakage still exists during spinning.

[0060] Comparative Example 4

[0061] A method for preparing a cationic polyester differs from Example 1 in that: no polyether diol is added; and the polycondensation reaction time is 90 min.

[0062] Tests showed that the final cationic polyester had a breakage rate of 2 times per hour during melt spinning.

[0063] Compared with Example 1, Comparative Example 4 showed a significantly shorter polycondensation reaction time and a significantly worse spinnability of the cationic polyester. This is because Comparative Example 4 did not add polyether diol, lacking the flexible chain regulation of polyether diol. The melt viscosity rise rate was not buffered, and the polycondensation reaction reached the power threshold faster. At the same time, the molecular chain rigidity was relatively high, which increased the chain segment slip resistance during spinning and increased the probability of filament breakage.

[0064] Example 2

[0065] A method for preparing cationic polyester differs from Example 1 in that: the amount of polyether diol added is 25.1% of the theoretical yield of cationic polyester; and the polycondensation reaction time is 175 min.

[0066] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0067] Example 3

[0068] A method for preparing cationic polyester differs from Example 1 in that: the metal dicarboxylate is zinc dimalonate, the amount of polyether diol added is 25.1% of the theoretical yield of cationic polyester, and the polycondensation reaction time is 160 min.

[0069] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0070] Example 4

[0071] A method for preparing cationic polyester differs from Example 1 in that: the metal dicarboxylate is zinc disuccinate, the amount of polyether diol added is 25.1% of the theoretical yield of cationic polyester, and the polycondensation reaction time is 165 min.

[0072] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0073] Example 5

[0074] A method for preparing cationic polyester differs from Example 1 in that: the metal dicarboxylate is magnesium dimalonate, the amount of polyether diol added is 25.1% of the theoretical yield of cationic polyester, and the polycondensation reaction time is 170 min.

[0075] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0076] Example 6

[0077] A method for preparing cationic polyester differs from Example 1 in that: the metal dicarboxylate is magnesium disuccinate, the amount of polyether diol added is 25.1% of the theoretical yield of cationic polyester, and the polycondensation reaction time is 175 min.

[0078] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0079] Example 7

[0080] A method for preparing cationic polyester differs from Example 1 in that: the metal dicarboxylate is magnesium adipate, the amount of polyether diol added is 25.1% of the theoretical yield of cationic polyester, and the polycondensation reaction time is 180 min.

[0081] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0082] Example 8

[0083] A method for preparing a cationic polyester, comprising the following specific steps:

[0084] (1) Preparation of materials;

[0085] Dicarboxylic acid: terephthalic acid;

[0086] Aliphatic diols: 1,4-Butanediol;

[0087] Polyether diol: Polytetrahydrofuran ether diol, with a molecular weight of 1000 g / mol;

[0088] Metal dicarboxylate: Zinc diisophthalate;

[0089] Catalyst: Tetrabutyl titanate;

[0090] Stabilizer: Triphenyl phosphate;

[0091] (2) Preparation of cationic polyester;

[0092] (a) After mixing the diacid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification reaction at 220°C and 0.3 MPa under nitrogen or inert atmosphere (with stirring at 40 rpm) until the esterification rate reaches 98%. Then the pressure is released to atmospheric pressure to end the esterification.

[0093] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 255°C and an absolute pressure of ≤100Pa, and then polycondensation reaction is carried out for 120 minutes to obtain cationic polyester.

[0094] In steps (a) to (b), the mass of the metal dicarboxylate is 1 / 20 of the mass of the diacid, the molar ratio of the aliphatic diol to the diacid is 1.5:1, the amount of polyether diol added is 5.84% of the theoretical yield of cationic polyester, the amount of catalyst used is 500 ppm of the theoretical yield of cationic polyester, and the amount of stabilizer used is 300 ppm of the theoretical yield of cationic polyester.

[0095] Tests show that the final cationic polyester (NMR spectrum as shown in Figure 1) has good properties. Figure 1 As shown, the number of yarn breaks during the melt spinning process is 0 times / hour.

[0096] Comparative Example 5

[0097] A method for preparing a cationic polyester differs from Example 8 in that: no polyether diol is added; and the polycondensation reaction time is 80 min.

[0098] Tests showed that the final cationic polyester had a breakage rate of 1 per hour during melt spinning.

[0099] Compared with Example 8, Comparative Example 5 showed a significantly shorter polycondensation reaction time and a significantly worse spinnability of the cationic polyester. This is because without the addition of polyether diol, the melt lacks the flexible chain regulation of polyether diol, resulting in no buffering of viscosity increase and a faster polycondensation reaction reaching the power limit. Furthermore, the molecular chain rigidity is relatively high, making the fibers prone to breakage due to stress concentration during spinning, thus increasing the number of fiber breaks.

[0100] Example 9

[0101] A method for preparing a cationic polyester differs from Example 8 in that: the polyether diol is polyethylene glycol with a molecular weight of 1000 g / mol; and the polycondensation reaction time is 120 min.

[0102] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0103] Example 10

[0104] A method for preparing a cationic polyester differs from Example 8 in that: the polyether diol is a polypropylene oxide diol with a molecular weight of 1000 g / mol; and the polycondensation reaction time is 140 min.

[0105] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0106] Example 11

[0107] A method for preparing a cationic polyester differs from Example 8 in that: the aliphatic diol is 1,3-propanediol; and the polycondensation reaction time is 125 min.

[0108] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0109] Comparative Example 6

[0110] A method for preparing a cationic polyester differs from that in Example 11 in that: no polyether diol is added; and the polycondensation reaction time is 95 min.

[0111] Tests showed that the final cationic polyester had a breakage rate of 5 times per hour during melt spinning.

[0112] Compared with Example 11, Comparative Example 6 showed a significantly shorter polycondensation reaction time and a significantly worse spinnability of the cationic polyester. This is because no polyether diol was added, and the lack of viscosity buffering provided by the polyether diol resulted in a faster rate of increase in melt viscosity and a shorter polycondensation reaction time. At the same time, the rigidity of the molecular chain was not improved by the flexible chain, which increased the resistance to chain segment movement during spinning and led to a high frequency of filament breakage.

[0113] Example 12

[0114] A method for preparing a cationic polyester differs from Example 11 in that: the polyether diol is polyethylene glycol with a molecular weight of 1000 g / mol; and the polycondensation reaction time is 124 min.

[0115] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0116] Example 13

[0117] A method for preparing cationic polyester differs from that in Example 12 in that the amount of polyether diol added is 23% of the theoretical yield of cationic polyester; and the polycondensation reaction time is 160 min.

[0118] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0119] Example 14

[0120] A method for preparing a cationic polyester, comprising the following specific steps:

[0121] (1) Preparation of materials;

[0122] Dicarboxylic acid: isophthalic acid;

[0123] Aliphatic diols: Neopentyl glycol;

[0124] Polyether diol: polyethylene glycol, with a molecular weight of 5000 g / mol;

[0125] Metal dicarboxylate: calcium diisophthalate;

[0126] Catalyst: Tetrabutyl titanate;

[0127] Stabilizer: Tributyl phosphate;

[0128] (2) Preparation of cationic polyester;

[0129] (a) After mixing the dicarboxylic acid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification reaction at 190°C and 0.5 MPa under nitrogen or inert atmosphere (with stirring at 40 rpm) until the esterification rate reaches 95%. Then the pressure is released to atmospheric pressure to end the esterification.

[0130] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 230°C and an absolute pressure of ≤100Pa, and then polycondensation reaction is carried out for 120 minutes to obtain cationic polyester.

[0131] In steps (a) to (b), the mass of the metal dicarboxylate is 1 / 200 of the mass of the diacid, the molar ratio of the aliphatic diol to the diacid is 1.1:1, the amount of polyether diol added is 10% of the theoretical yield of cationic polyester, the amount of catalyst used is 50 ppm of the theoretical yield of cationic polyester, and the amount of stabilizer used is 300 ppm of the theoretical yield of cationic polyester.

[0132] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0133] Example 15

[0134] A method for preparing a cationic polyester, comprising the following specific steps:

[0135] (1) Preparation of materials;

[0136] Dicarboxylic acid: succinic acid;

[0137] Aliphatic diols: 1,4-Butanediol;

[0138] Polyether diol: Polytetrahydrofuran ether diol, with a molecular weight of 600 g / mol;

[0139] Metal dicarboxylate: magnesium diisophthalate;

[0140] Catalyst: Germanium dioxide;

[0141] Stabilizer: Triphenyl phosphite;

[0142] (2) Preparation of cationic polyester;

[0143] (a) After mixing the diacid, aliphatic diol, polyether diol, metal dicarboxylate and catalyst, the mixture is subjected to esterification reaction at 190°C and 0.5 MPa under nitrogen or inert atmosphere (with stirring at 40 rpm) until the esterification rate reaches 98%, then the pressure is released to atmospheric pressure to end the esterification.

[0144] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 230°C and an absolute pressure of ≤100Pa, and then polycondensation reaction is carried out for 130 minutes to obtain cationic polyester.

[0145] In steps (a) to (b), the mass of the metal dicarboxylate is 1 / 150 of the mass of the diacid, the molar ratio of the aliphatic diol to the diacid is 1.3:1, the amount of polyether diol added is 20% of the theoretical yield of cationic polyester, the amount of catalyst used is 100 ppm of the theoretical yield of cationic polyester, and the amount of stabilizer used is 50 ppm of the theoretical yield of cationic polyester.

[0146] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0147] Example 16

[0148] A method for preparing a cationic polyester, comprising the following specific steps:

[0149] (1) Preparation of materials;

[0150] Dicarboxylic acid: adipic acid;

[0151] Aliphatic diols: 1,3-propanediol;

[0152] Polyether diol: Polytetrahydrofuran ether diol, with a molecular weight of 2000 g / mol;

[0153] Metal dicarboxylate: calcium terephthalate;

[0154] Catalyst: Tetrabutyl titanate;

[0155] Stabilizer: Antioxidant 1010;

[0156] (2) Preparation of cationic polyester;

[0157] (a) After mixing the dicarboxylic acid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification reaction at 250°C and 0.3 MPa under nitrogen or inert atmosphere (with stirring at 40 rpm) until the esterification rate reaches 97%. Then the pressure is released to atmospheric pressure to end the esterification.

[0158] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 270°C and an absolute pressure of ≤100Pa, and then polycondensation reaction is carried out for 140 minutes to obtain cationic polyester.

[0159] In steps (a) to (b), the mass of the metal dicarboxylate is 1 / 120 of the mass of the diacid, the molar ratio of the aliphatic diol to the diacid is 1.5:1, the amount of polyether diol added is 30% of the theoretical yield of cationic polyester, the amount of catalyst used is 300 ppm of the theoretical yield of cationic polyester, and the amount of stabilizer used is 1000 ppm of the theoretical yield of cationic polyester.

[0160] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0161] Example 17

[0162] A method for preparing a cationic polyester, comprising the following specific steps:

[0163] (1) Preparation of materials;

[0164] Dicarboxylic acid: isophthalic acid;

[0165] Aliphatic diols: Ethylene glycol;

[0166] Polyether diol: Polypropylene oxide diol, with a molecular weight of 2000 g / mol;

[0167] Metal dicarboxylate: magnesium diterephthalate;

[0168] Catalyst: Antimony glycol;

[0169] Stabilizer: Antioxidant 245;

[0170] (2) Preparation of cationic polyester;

[0171] (a) After mixing the dicarboxylic acid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification reaction at 250°C and 0.3 MPa under nitrogen or inert atmosphere (with stirring at 40 rpm) until the esterification rate reaches 97%. Then the pressure is released to atmospheric pressure to end the esterification.

[0172] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 270°C and an absolute pressure of ≤100Pa, and then polycondensation reaction is carried out for 120 minutes to obtain cationic polyester.

[0173] In steps (a) to (b), the mass of the metal dicarboxylate is 1 / 100 of the mass of the diacid, the molar ratio of the aliphatic diol to the diacid is 1.8:1, the amount of polyether diol added is 40% of the theoretical yield of cationic polyester, the amount of catalyst used is 500 ppm of the theoretical yield of cationic polyester, and the amount of stabilizer used is 1500 ppm of the theoretical yield of cationic polyester.

[0174] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0175] Example 18

[0176] A method for preparing a cationic polyester, comprising the following specific steps:

[0177] (1) Preparation of materials;

[0178] Dicarboxylic acid: isophthalic acid;

[0179] Aliphatic diols: Ethylene glycol;

[0180] Polyether diol: Polyethylene oxide-propylene oxide copolymer diol with a molecular weight of 1000 g / mol;

[0181] Metal dicarboxylate: Zinc diterephthalate;

[0182] Catalyst: Tetraisopropyl titanate;

[0183] Stabilizer: Triphenyl phosphate;

[0184] (2) Preparation of cationic polyester;

[0185] (a) After mixing the dicarboxylic acid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification reaction at 270°C and 0 MPa under nitrogen or inert atmosphere (with stirring at a speed of 40 rpm) until the esterification rate reaches 97%. Then the pressure is released to atmospheric pressure to end the esterification.

[0186] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 290°C and an absolute pressure of ≤100Pa, and then polycondensation reaction is carried out for 140 minutes to obtain cationic polyester.

[0187] In steps (a) to (b), the mass of the metal dicarboxylate is 1 / 60 of the mass of the diacid, the molar ratio of the aliphatic diol to the diacid is 2:1, the amount of polyether diol added is 50% of the theoretical yield of cationic polyester, the amount of catalyst used is 800 ppm of the theoretical yield of cationic polyester, and the amount of stabilizer used is 2200 ppm of the theoretical yield of cationic polyester.

[0188] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0189] Example 19

[0190] A method for preparing a cationic polyester, comprising the following specific steps:

[0191] (1) Preparation of materials;

[0192] Dicarboxylic acid: terephthalic acid;

[0193] Aliphatic diols: Ethylene glycol;

[0194] Polyether diol: Polyethylene oxide-propylene oxide copolymer diol with a molecular weight of 2000 g / mol;

[0195] Metal dicarboxylate: calcium dimalonate;

[0196] Catalyst: Tetrabutyl titanate;

[0197] Stabilizer: Triphenyl phosphate;

[0198] (2) Preparation of cationic polyester;

[0199] (a) After mixing the dicarboxylic acid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification reaction at 270°C and 0 MPa under nitrogen or inert atmosphere (with stirring at 40 rpm) until the esterification rate reaches 98%. Then the pressure is released to atmospheric pressure to end the esterification.

[0200] (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 290°C and an absolute pressure of ≤100Pa, and then polycondensation reaction is carried out for 120 minutes to obtain cationic polyester.

[0201] In steps (a) to (b), the mass of the metal dicarboxylate is 1 / 40 of the mass of the diacid, the molar ratio of the aliphatic diol to the diacid is 2.2:1, the amount of polyether diol added is 60% of the theoretical yield of cationic polyester, the amount of catalyst used is 1000 ppm of the theoretical yield of cationic polyester, and the amount of stabilizer used is 3000 ppm of the theoretical yield of cationic polyester.

[0202] Tests showed that the final cationic polyester had 0 yarn breaks per hour during melt spinning.

[0203] In all the above embodiments and comparative examples, the pressure reduction was stopped when the pressure of the reaction system during the polycondensation reaction was lower than 100 Pa.

Claims

1. A cationic polyester, characterized in that, It is prepared by reacting a dicarboxylic acid, an aliphatic diol, a polyether diol, and a metal dicarboxylate, wherein the mass of the metal dicarboxylate is less than 10% of the mass of the dicarboxylic acid. The structural formula of the metal dicarboxylate is: HOOC-R1-COO-M 2+ -COO-R2-COOH, where -R1- and -R2- are both chain segments composed of carbon and hydrogen atoms, and the number of carbon atoms in -R1- and -R2- is 1-8. The number of carbon atoms in -R1- and -R2- may be the same or different. M 2+ For Be 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Ra 2+ Fe 2+ Zn 2+ or Co 2+ .

2. The cationic polyester according to claim 1, characterized in that, The mass of the metal dicarboxylate is more than 0.5% of the mass of the dicarboxylic acid.

3. The cationic polyester according to claim 1, characterized in that, HOOC-R1-COO- and -COO-R2-COOH are oxalic acid segments, malonic acid segments, succinic acid segments, glutaric acid segments, adipic acid segments, hematonic acid segments, octanoic acid segments, cyclohexanedicarboxylic acid segments, terephthalic acid segments, isophthalic acid segments, or phthalic acid segments.

4. A cationic polyester according to claim 3, characterized in that, The metal dicarboxylate salts are magnesium dimalonate, zinc dimalonate, calcium dimalonate, magnesium disuccinate, calcium disuccinate, zinc disuccinate, magnesium diadhesive, calcium diadhesive, zinc diadhesive, calcium isophthalate, zinc isophthalate, magnesium isophthalate, calcium terephthalate, magnesium terephthalate, or zinc terephthalate.

5. A cationic polyester according to claim 1, characterized in that, The dicarboxylic acid is terephthalic acid, isophthalic acid, succinic acid, or adipic acid; the aliphatic diol is ethylene glycol, 1,3-propanediol, 1,4-butanediol, or neopentyl glycol; the polyether diol is polyethylene glycol, polytetrahydrofuran ether diol, polypropylene oxide diol, or polyethylene oxide-propylene oxide copolymer diol.

6. A cationic polyester according to claim 5, characterized in that, The molecular weight of polyethylene glycol is 1000-5000 g / mol, the molecular weight of polytetrahydrofuran ether diol is 600-2000 g / mol, the molecular weight of polypropylene oxide diol is 1000-2000 g / mol, and the molecular weight of polyethylene oxide-propylene oxide copolymer diol is 1000-2000 g / mol.

7. A cationic polyester according to claim 1, characterized in that, The molar ratio of aliphatic diol to diacid is 1.1-2.2:1; the amount of polyether diol added is 5-60% of the theoretical yield of cationic polyester.

8. A method for preparing a cationic polyester as described in any one of claims 1 to 7, characterized in that, Using diacid, aliphatic diol, polyether diol and metal dicarboxylate as reactants, esterification and polycondensation reactions are carried out sequentially to obtain cationic polyester.

9. The method according to claim 8, characterized in that, A catalyst is added before the esterification reaction. The catalyst is one or more of antimony trioxide, antimony glycolate, germanium dioxide, tetrabutyl titanate, and tetraisopropyl titanate. The amount of catalyst used is 50-1000 ppm of the theoretical yield of cationic polyester. A stabilizer is added after the esterification reaction and before the polycondensation reaction. The stabilizer is one or more of triphenyl phosphate, tributyl phosphate, triphenyl phosphite, antioxidant 1010, and antioxidant 245. The amount of stabilizer used is 50-3000 ppm of the theoretical yield of cationic polyester.

10. The method according to claim 9, characterized in that, The specific steps are as follows: (a) After mixing the dicarboxylic acid, aliphatic diol, polyether diol, metal dicarboxylate, and catalyst, the mixture is subjected to esterification under nitrogen or inert atmosphere at a temperature of 190-270℃ and a pressure of 0-0.5MPa until the esterification rate reaches 95%. Then the pressure is released to atmospheric pressure to end the esterification process. (b) After adding a stabilizer to the reaction system, the reaction system is gradually depressurized and heated to a temperature of 230-290℃ and an absolute pressure of ≤100Pa. The polycondensation reaction is carried out for more than 110 minutes to obtain cationic polyester.

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