Phosphorus-titanium polyester catalyst as well as preparation method and application thereof

Abstract

The invention discloses a phosphorus-titanium polyester catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalyst preparation. The structural general formula of the phosphorus-titanium polyester catalyst is # imgabs0, wherein R1 is selected from any one of hydroxyl, C1-C12 aliphatic alkoxy or aromatic alkoxy; and R2 is selected from C2-C12 aliphatic alkyl groups. The preparation method of the catalyst comprises the following steps: reacting dihalogenated phosphite ester with dihydric alcohol, and further reacting the obtained product with organic phthalic ester to prepare the phosphorus-titanium polyester catalyst. Starting from a molecular structure, a chelate ring structure which takes a titanium atom as a center and simultaneously contains two phosphorus and titanium elements is constructed through molecular design, the chelate ring structure is stable, and the coordination and electronegativity of the central titanium atom in the catalyst can be effectively adjusted; therefore, the problems of poor catalytic stability and hydrolysis resistance of a titanium catalyst in the prior art are effectively solved, and the quality of a polyester product is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and particularly relates to a phosphorus-titanium polyester catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Polyester is the synthetic polymer material with the largest production volume and the widest application in the world at present. It is usually prepared from dibasic acids and diols through direct esterification and polycondensation. In the preparation process of polyester, a suitable catalyst is often required to promote the growth of the molecular weight of polyester. At present, the polyester catalysts mostly used in industrial production and scientific research can be mainly divided into antimony-based catalysts, germanium-based catalysts, and titanium-based catalysts.

[0003] Antimony-based catalysts are the most commonly used polyester catalysts in industry at present. They have stable activity, few side reactions, low price, and good repeatability. However, antimony-based catalysts are easily reduced to metallic antimony during use, resulting in poor hue of polyester products. Moreover, antimony belongs to heavy metals and has certain toxicity, which will cause certain harm to organisms and the ecological environment during subsequent use. Germanium-based catalysts can produce polyester chips with good color, and the thermal degradation reaction is not obvious during the catalytic process. However, germanium resources in nature are scarce, the price is expensive, and the cost is high. Moreover, there are more ether bonds in the polyester products catalyzed by germanium, resulting in a decrease in melting point.

[0004] Titanium-based catalysts do not contain heavy metals, are non-toxic and harmless to organisms, have high reaction activity, and relatively low price, so they are favored by people. At present, titanium-based catalysts can be divided into inorganic titanium catalysts and organic titanium catalysts. Inorganic titanium catalysts have a stable structure, but their solubility and dispersibility are poor, and their performance is not stable enough. Organic titanium catalysts have high catalytic activity, but it is difficult to control the reaction during the preparation of polyester, and there are many side reactions. The products are prone to yellowing, and organic titanium catalysts themselves also have problems such as poor chemical stability and easy hydrolysis. Therefore, improving the stability of titanium-based catalysts and overcoming problems such as easy yellowing of products are the prerequisites for the large-scale application of titanium-based catalysts.

[0005] Studies have shown that titanium diol complexes have been widely accepted due to their stable cyclic chelate structure. They have advantages such as good hydrolysis resistance, insensitivity to light, and easy storage. However, such catalysts often cause more side reactions due to their too high activity, break the molecular chain, resulting in polyester chips with not only unsatisfactory viscosity but also serious yellow edges and poor hue. To overcome this problem, introducing phosphonate groups into titanium diol complexes is a feasible solution.

[0006] Patent CN108484895B and Patent CN108641070B provide a series of phosphorus-titanium composite catalysts for polyesters and preparation methods thereof. The prepared catalysts contain a central titanium atom and at least two chelate rings, and at least one phosphonate group is connected to each chelate ring through a substituent. The polyester catalyst with this structure has the advantages of stable performance and excellent color value of the prepared product. However, since the phosphonate group is connected to the chelate ring through a substituent rather than constituting the main body of the chelate ring, it has strict restrictions on the number of carbon atoms in both the chelate ring and the substituent. Too many carbon atoms will lead to too large steric hindrance and it is not easy to form an effective coordination between phosphorus and titanium; too few carbon atoms will lead to difficulty in forming a ring. In addition, they both undergo a hydrolysis step in the preparation process. Due to the poor hydrolysis stability of the structure of phosphite itself, a large amount of phosphite structure will inevitably hydrolyze and be lost in this step, resulting in a large amount of raw materials being wasted and the synthesis efficiency being low. Therefore, there are many limiting factors, great preparation difficulty, low synthesis efficiency and other problems in the actual preparation process of this phosphorus-titanium polyester catalyst. Summary of the Invention

[0007] The object of the present invention is to provide a phosphorus-titanium polyester catalyst, its preparation method and application in view of the technical problems of poor chemical stability, easy hydrolysis of existing titanium-based catalysts, and easy yellowing of the prepared polyesters, as well as many limiting factors and great preparation difficulty in the preparation process of existing phosphorus-titanium catalysts.

[0008] In order to achieve the above technical objectives, the first aspect of the present invention provides a phosphorus-titanium polyester catalyst, and the general structural formula of the phosphorus-titanium polyester catalyst is:

[0009]

[0010] In the formula, R1 is selected from any one of a hydroxyl group, a C1-C12 aliphatic alkoxy group or an aromatic alkoxy group;

[0011] R2 is selected from a C2-C12 aliphatic alkyl group.

[0012] Starting from the molecular structure, through molecular design, the present invention constructs a novel phosphorus-titanium polyester catalyst centered around titanium atoms and containing two phosphite ester structures. The phosphite ester structures are connected to the central titanium atoms through alkoxy bonds, thus forming two chelate rings containing phosphorus and titanium elements. The phosphorus-titanium polyester catalyst of the present invention has the following performance advantages. On the one hand, due to its unique electronic arrangement and stable chemical bonding state, the titanium-oxy structure in the chelate ring can effectively resist the attack of hydrogen bonds and hydrogen-oxygen bonds in water molecules. This stability enables the phosphorus-titanium polyester catalyst of the present invention to maintain a long service life under hydrolysis conditions, thereby enhancing its hydrolysis resistance. On the other hand, during the polyester polymerization process, titanium atoms act as catalysts to accelerate the polymerization reaction. However, too high catalytic activity may lead to side reactions of thermal degradation of the polyester in the later stage of polymerization. The phosphite ester structure in the phosphorus-titanium polyester catalyst of the present invention can react with titanium atoms to form titanium phosphonate compounds, which can effectively reduce the catalytic activity of titanium elements, thereby avoiding the occurrence of such thermal degradation side reactions. This regulation mechanism makes the polymerization process more controllable and improves the quality of polyester products. At the same time, the compound centered around titanium atoms and containing two phosphite ester structures proposed by the present invention has broad application prospects in the field of polyester polymerization. Its unique molecular structure and performance advantages enable the compound to be used as an efficient catalyst or catalyst assistant to improve the efficiency and product quality of polyester polymerization.

[0013] In the second aspect of the present invention, a preparation method of the phosphorus-titanium polyester catalyst described in the first aspect is provided, including the following steps:

[0014] S1: Under the protection of an inert gas, add dihalophosphite to a mixed solution of aliphatic diol and an acid-binding agent, stir at 20 - 60 °C for 5 - 10 h, and obtain bis(diol-substituted) phosphite through filtration and vacuum distillation;

[0015] S2: Under the protection of an inert gas, dissolve organic phthalate in an organic solvent, then add the bis(diol-substituted) phosphite described in step S1, stir at 20 - 60 °C for 3 - 8 h, and obtain a solid product, the phosphorus-titanium polyester catalyst, through filtration, washing, and drying.

[0016] The present invention directly reacts dihalophosphite with diol in the presence of an acid-binding agent to prepare bis(diol-substituted) phosphite containing a diol structure. Compared with the prior art of introducing epoxy or ketal structures into phosphite ester groups and then further hydrolyzing to obtain phosphite esters with diol structures, the preparation method used in the present invention does not require the participation of water, thereby effectively avoiding the hydrolysis behavior of the phosphite ester structure.

[0017] The R & D team of the present invention prepared a phosphorus-titanium polyester catalyst through a large number of experiments. The sequence of preparation steps, types of raw materials, addition sequence of raw materials, and proportional relationship of raw materials are all special. Any change will lead to failure in preparation and the target product cannot be obtained. Embodiments of the present invention illustrate relevant preparation methods.

[0018] Further, the general structural formula of the dihalophosphite in step S1 is wherein R1 is selected from any one of a hydroxyl group, a C1-C12 aliphatic alkoxy group, or an aromatic alkoxy group, preferably a methoxy group, an ethoxy group, a propoxy group, and a phenoxy group, and X is selected from any one of halogen elements, preferably a chlorine element.

[0019] Further, the aliphatic diol in step S1 is any one of C2-C12 aliphatic diols, preferably any one or more of ethylene glycol, 1,3-propanediol, and 1,4-butanediol.

[0020] Further, the acid-binding agent in step S1 is any one or more of triethylamine, pyridine, and 4-dimethylaminopyridine.

[0021] Further, the molar ratio of the dihalophosphite, aliphatic diol, and acid-binding agent in step S1 is 1:(2.2-5):(2.2-3).

[0022] Further, the organotitanate in step S2 is at least one of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, alkoxy phthalate, diisopropyl bis(acetylacetonato)titanate, tetra-tert-butyl phthalate, and alkyl phthalate, preferably at least one of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and alkoxy phthalate.

[0023] Further, the organic solvent in step S2 is an anhydrous solvent capable of dissolving the organic phthalate, preferably anhydrous petroleum ether.

[0024] Further, the molar ratio of the bis(diol)phosphite to the organic phthalate in step S2 is (2.1-2.5):1.

[0025] The third aspect of the present invention provides an application of the phosphorus-titanium polyester catalyst described in the first aspect or the phosphorus-titanium polyester catalyst prepared by the preparation method described in the second aspect in polyester preparation. Using a dibasic acid and a diol as reaction monomers, an esterification reaction, a pre-polycondensation reaction, and a final polycondensation reaction are sequentially carried out under the action of the phosphorus-titanium polyester catalyst;

[0026] wherein the dibasic acid is one or more of aliphatic, cycloaliphatic, or aromatic dibasic acids with a carbon number not exceeding 10;

[0027] And / or, the diol is one or more of aliphatic, cycloaliphatic or aromatic diols having no more than 10 carbon atoms;

[0028] And / or, the molar ratio of the dibasic acid to the diol is 1:(1.2 - 2.0);

[0029] And / or, the usage amount of the phosphorus-titanium polyester catalyst is based on the mass of theoretically generated polyester, and the mass ratio of titanium atoms is 1 - 20 ppm.

[0030] Furthermore, the temperature of the esterification reaction is 140 - 240 °C, the pressure is 0 - 0.5 MPaG, the stirring rate is 50 - 200 rpm, and the reaction time is 1 - 4 h;

[0031] The temperature of the pre-polycondensation reaction is 180 - 260 °C, the pressure is 5 - 50 KPaA, the stirring rate is 50 - 200 rpm, and the reaction time is 0.5 - 2 h;

[0032] The temperature of the final polycondensation reaction is 220 - 300 °C, the pressure is 20 - 200 PaA, the stirring rate is 50 - 200 rpm, and the reaction time is 0.1 - 1 h.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) In the phosphorus-titanium polyester catalyst of the present invention, the phosphite structure is connected with titanium atoms through alkoxy bonds to form a chelate ring structure. It is easier to form effective coordination between phosphorus and titanium, and it is not affected by the number of carbon atoms on the chelate ring, with stable performance; compared with directly mixing phosphite into the titanium-based catalyst, its chemical structure is stable and it has excellent hydrolysis resistance.

[0035] (2) The phosphorus-titanium polyester catalyst of the present invention is a solid catalyst, which is convenient for storage and transportation. And due to the presence of a large number of alkoxy structures in the catalyst structure, the catalyst has good dispersibility both in the monomers for polyester reaction and in the oligomer melt, thus ensuring the stability of catalytic performance.

[0036] (3) The preparation method of the phosphorus-titanium polyester catalyst of the present invention is simple. The preparation process does not require the participation of water, has few limiting factors in the preparation process, the reaction is mild, and it is easy to carry out large-scale production.

[0037] (4) The phosphorus-titanium polyester catalyst of the present invention can be applied to the production of polyester products. The presence of the phosphite structure in the phosphorus-titanium polyester catalyst can effectively adjust the coordination and electronegativity of the central titanium atoms of the catalyst, and can effectively inhibit the too high catalytic activity of titanium elements. While ensuring the smooth preparation of polyester, it effectively inhibits the occurrence of side reactions such as thermal degradation and thermo-oxidative degradation, and improves the quality of polyester products. Detailed implementation mode

[0038] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any form, that is, it is not intended to limit the protection scope of the present invention.

[0039] The mention of "embodiment" in this article means that the specific features or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0040] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention pertains. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0041] In the present application, the intrinsic viscosity of PET / PCT is tested according to the method of "GB / T 14190-2008 Test Methods for Fiber Grade Polyester Chips (PET)". The solvent is phenol / 1,1,2,2-tetrachloroethane (mass ratio 50:50), and the number of the Ubbelohde capillary viscometer is 4-0.8.

[0042] The intrinsic viscosity of PTT is tested according to the method described in "FZ / T 51010-2014 Fiber Grade Poly(trimethylene terephthalate) (PTT)". The solvent is phenol / 1,1,2,2-tetrachloroethane (mass ratio 60:40), and the number of the Ubbelohde capillary viscometer is 4-0.8.

[0043] The intrinsic viscosity of PBT is tested according to the method of "HG / T 5510-2019 Plastics Poly(butylene terephthalate) (PBT) Resin". The solvent is phenol / 1,1,2,2-tetrachloroethane (mass ratio 60:40), and the number of the Ubbelohde capillary viscometer is 4-0.8.

[0044] The intrinsic viscosity of PBS is tested according to the method of "GB / T 30294-2013 Poly(butylene succinate)". The solvent is phenol / 1,1,2,2-tetrachloroethane (mass ratio 50:50), and the number of the Ubbelohde capillary viscometer is 4-0.8.

[0045] The carboxyl content of PET / PTT / PBT / PCT / PBS was determined according to Method A specified in "Test Methods for Fiber-grade Polyester Chips (PET) - GB / T 14190-2008". The mixed solvent used was phenol-chloroform with a volume ratio of 2:3. The standard titration solution was potassium hydroxide-benzyl alcohol, and the indicator was bromophenol blue.

[0046] The color values of PET / PTT / PBT / PCT / PBS were determined according to the provisions of 5.5.2 in "Test Methods for Fiber-grade Polyester Chips (PET) - GB / T 14190-2008", using the CIE1976L*a*b* color system. In this system, L is the lightness factor, and a and b are color measurement numbers. Among them, b represents the yellow-blue balance, which is of great significance to the color of polyester. The closer the b value is to 0, the more standard the color.

[0047] Preparation of Phosphorus-Titanium Polyester Catalyst

[0048] Example 1

[0049] This example provides a method for preparing a phosphorus-titanium polyester catalyst, which includes the following steps:

[0050] S1: Under the protection of nitrogen, ethyl dichlorophosphite was slowly dropped into the mixed solution composed of ethylene glycol and triethylamine for reaction. The molar ratio of the addition amounts of ethyl dichlorophosphite, ethylene glycol, and triethylamine was 1:2.2:2.2, and it was stirred at 20 °C for 10 h. After the reaction ended, the obtained suspension was filtered to remove insoluble substances, and then the product bis(2-hydroxyethyl) phosphite was obtained by vacuum distillation.

[0051] S2: Under the protection of nitrogen, tetraethyl titanate was dissolved in anhydrous petroleum ether, and the product bis(2-hydroxyethyl) phosphite obtained in step S1 was slowly added to the tetraethyl titanate / anhydrous petroleum ether solution for reaction. The molar ratio of the usage amounts of bis(2-hydroxyethyl) phosphite and tetraethyl titanate was 2.1:1, and it was stirred at 20 °C for 8 h. After the reaction ended, the obtained suspension was filtered to collect the insoluble substances therein, and the collected insoluble substances were washed with petroleum ether and then dried under vacuum to obtain the target catalyst, named Catalyst I.

[0052] Example 2

[0053] This example provides a method for preparing a phosphorus-titanium polyester catalyst, which includes the following steps:

[0054] S1: Under nitrogen protection, slowly drop methyl dichlorophosphite into the mixed solution composed of 1,3 - propanediol and pyridine for reaction. The molar ratio of the addition amounts of methyl dichlorophosphite, 1,3 - propanediol and pyridine is 1:5:3, and stir at 60 °C for 5 h. After the reaction ends, filter the obtained suspension to remove insoluble substances, and then obtain the product bis(1,3 - propanediol) phosphite by vacuum distillation.

[0055] S2: Under nitrogen protection, dissolve tetra - isopropyl titanate in anhydrous petroleum ether, and slowly add the product bis(1,3 - propanediol) phosphite obtained in step S1 into the tetra - isopropyl titanate / anhydrous petroleum ether solution for reaction. The molar ratio of the usage amounts of bis(1,3 - propanediol) phosphite and tetra - isopropyl titanate is 2.5:1, and stir at 60 °C for 3 h. After the reaction ends, filter the obtained suspension to collect the insoluble substances therein, and wash the collected insoluble substances with petroleum ether and then conduct vacuum drying to obtain the target catalyst, named catalyst II.

[0056] Example 3

[0057] This example provides a preparation method of a phosphorus - titanium polyester catalyst, including the following steps:

[0058] S1: Under nitrogen protection, slowly drop propyl dichlorophosphite into the mixed solution composed of 1,4 - butanediol and 4 - dimethylaminopyridine for reaction. The molar ratio of the addition amounts of propyl dichlorophosphite, 1,4 - butanediol and 4 - dimethylaminopyridine is 1:3:2.5, and stir at 40 °C for 7 h. After the reaction ends, filter the obtained suspension to remove insoluble substances, and then obtain the product bis(1,4 - butanediol) phosphite by vacuum distillation.

[0059] S2: Under nitrogen protection, dissolve tetra - butyl titanate in anhydrous petroleum ether, and slowly add the product bis(1,4 - butanediol) phosphite obtained in step S1 into the tetra - butyl titanate / anhydrous petroleum ether solution for reaction. The molar ratio of the usage amounts of bis(1,4 - butanediol) phosphite and tetra - butyl titanate is 2.3:1, and stir at 40 °C for 5 h. After the reaction ends, filter the obtained suspension to collect the insoluble substances therein, and wash the collected insoluble substances with petroleum ether and then conduct vacuum drying to obtain the target catalyst, named catalyst III.

[0060] Example 4

[0061] This example provides a preparation method of a phosphorus - titanium polyester catalyst, including the following steps:

[0062] S1: Under nitrogen protection, diphenyl dichlorophosphite was slowly dropped into a mixed solution composed of 1,4-butanediol and 4-dimethylaminopyridine for reaction. The molar ratio of the addition amounts of diphenyl dichlorophosphite, 1,4-butanediol, and 4-dimethylaminopyridine was 1:3:2.5, and it was stirred at 40 °C for 8 h. After the reaction was completed, the obtained suspension was filtered to remove insoluble substances, and then the product bis(1,4-butanediol) phenylphosphite was obtained by vacuum distillation.

[0063] S2: Under nitrogen protection, tetrabutyl titanate was dissolved in anhydrous petroleum ether, and the product bis(1,4-butanediol) phenylphosphite obtained in step S1 was slowly added to the tetrabutyl titanate / anhydrous petroleum ether solution for reaction. The molar ratio of the usage amounts of bis(1,4-butanediol) phenylphosphite and tetrabutyl titanate was 2.4:1, and it was stirred at 40 °C for 6 h. After the reaction was completed, the obtained suspension was filtered to collect the insoluble substances therein, and the collected insoluble substances were washed with petroleum ether and then dried under vacuum to obtain the target catalyst, named catalyst Ⅳ.

[0064] Comparative Example 1

[0065] Compared with Example 3, in the preparation process of the phosphorus-titanium polyester catalyst in Comparative Example 1, the dropping order of the materials was different, and the other conditions were the same as those in Example 3. The specific process is as follows:

[0066] Under nitrogen protection, 1,4-butanediol was slowly dropped into a mixed solution composed of dipropyl dichlorophosphite and 4-dimethylaminopyridine for reaction. The molar ratio of the addition amounts of dipropyl dichlorophosphite, 1,4-butanediol, and 4-dimethylaminopyridine was 1:3:2.5, and it was stirred at 40 °C for 7 h. After the reaction was completed, the obtained suspension was filtered to remove insoluble substances, and then the filtrate was subjected to vacuum distillation, and the target product bis(1,4-butanediol) propylphosphite could not be obtained, so the next step could not be carried out.

[0067] Comparative Example 2

[0068] Compared with Example 3, in Comparative Example 2, 1,4-butanediol used in the preparation process of the phosphorus-titanium polyester catalyst was changed to n-butanol, and the other conditions were the same as those in Example 3.

[0069] S1: Under nitrogen protection, dipropyl dichlorophosphite was slowly dropped into a mixed solution composed of n-butanol and 4-dimethylaminopyridine for reaction. The molar ratio of the addition amounts of dipropyl dichlorophosphite, n-butanol, and 4-dimethylaminopyridine was 1:3:2.5, and it was stirred at 40 °C for 7 h. After the reaction was completed, the obtained suspension was filtered to remove insoluble substances, and then the product bis(n-butanol) propylphosphite was obtained by vacuum distillation.

[0070] S2: Under the condition of nitrogen protection, dissolve tetrabutyl titanate in anhydrous petroleum ether, and slowly add the product dipropyl phosphite bis(n-butyl alcohol) obtained in step S1 into the tetrabutyl titanate / anhydrous petroleum ether solution for reaction. The molar ratio of the usage amount of dipropyl phosphite bis(n-butyl alcohol) to tetrabutyl titanate is 2.3:1, and stir at 40 °C for 5 h. After the stirring ends, the system is still a homogeneous solution. After detection, no reaction occurs in the system, and no new catalyst is formed.

[0071] Comparative Example 3

[0072] Compared with Example 3, in Comparative Example 3, the molar ratio of the feed of dichloropropyl phosphite to 1,4-butanediol in the preparation process of the phosphorus-titanium polyester catalyst was changed to 1:1.5, and the other conditions remained unchanged.

[0073] Under the condition of nitrogen protection, slowly drop dichloropropyl phosphite into the mixed solution composed of 1,4-butanediol and 4-dimethylaminopyridine for reaction. The molar ratio of the addition amounts of dichloropropyl phosphite, 1,4-butanediol and 4-dimethylaminopyridine is 1:1.5:2.5, and stir at 40 °C for 7 h. After the reaction ends, filter the obtained suspension to remove insoluble substances, and then perform vacuum distillation. The target product dipropyl phosphite bis(1,4-butyl alcohol) cannot be obtained, and the next step cannot be carried out.

[0074] The preparation method of the novel phosphorus-titanium polyester catalyst of the present invention is optimized through a large number of experimental verifications. Changing the preparation steps, types of raw materials, raw material ratios, etc. may result in the failure to smoothly prepare the novel phosphorus-titanium polyester catalyst.

[0075] Compared with Comparative Example 1, Example 3 only changed the addition order of 1,4-butanediol and dichloropropyl phosphite. When the addition order of 1,4-butanediol and dichloropropyl phosphite is changed to drop 1,4-butanediol into dichloropropyl phosphite, dichloropropyl phosphite is always in excess in the reaction system at the initial stage of dropping, which will cause the failure to generate the target product dipropyl phosphite bis(1,4-butyl alcohol) in the reaction system, but a large amount of oligomers will precipitate out from the system, and the catalyst cannot be prepared.

[0076] Compared with Comparative Example 2, Example 3 only changed the diol 1,4-butanediol to the monohydric alcohol n-butanol. Although n-butanol can react with dichloropropyl phosphite to form dipropyl phosphite bis(n-butyl alcohol), the product structure does not have a diol structure and cannot further complex with phthalate ester to prepare the catalyst.

[0077] In Example 3, compared with Comparative Example 3, the feeding molar ratio of propyl dichlorophosphite to 1,4-butanediol in the preparation process of the phosphorus-titanium polyester catalyst was changed to 1:1.5. Since the usage amount of 1,4-butanediol is lower than the theoretical amount, a large amount of oligomers will also precipitate from the system during the preparation process, and the target product, bis(1,4-butanediol)propyl phosphite, cannot be formed, thus the catalyst cannot be prepared.

[0078] Preparation of Polyester

[0079] Example 5

[0080] The catalyst I prepared in Example 1 was used for the preparation of polyethylene terephthalate (PET), and the steps were as follows:

[0081] Terephthalic acid and ethylene glycol were put into a polymerization kettle according to a molar ratio of 1:1.2, and catalyst I with a titanium element content of 1 ppm was added to the polymerization kettle. At this time, the phosphorus element content was 1.5 ppm. The reaction materials were subjected to esterification, pre-polycondensation, and final polycondensation reactions in sequence. The esterification reaction temperature was 220 °C, the pressure was 0.5 MPaG, and the stirring rate was 200 rpm. When the amount of water collected at the water outlet reached 90% of the theoretical water output, the esterification reaction was considered to be over, and at this time, the total reaction time was 2 h. Subsequently, the esterification reaction solution was subjected to a pre-polycondensation reaction, where the pre-polycondensation reaction temperature was 240 °C, the reaction pressure was 50 KPaA, the stirring rate was 200 rpm, and the reaction time was 1.5 h. After the pre-polycondensation reaction was over, the pre-polycondensation reaction solution was subjected to a final polycondensation reaction, where the final polycondensation reaction temperature was 260 °C, the reaction pressure was 200 PaA, the stirring rate was 200 rpm, and the reaction time was 1 h. After the reaction was over, the polymer melt was transferred to water for cooling, stretching, pelletizing, and drying to obtain PET chips.

[0082] Example 6

[0083] The catalyst II prepared in Example 2 was used for the preparation of polytrimethylene terephthalate (PTT), and the steps were as follows:

[0084] Terephthalic acid and 1,3-propanediol were charged into a polymerization kettle at a molar ratio of 1:1.5, and catalyst II with a titanium element content of 5 ppm was added to the polymerization kettle. At this time, the phosphorus element content was 7.5 ppm. The reaction materials were successively subjected to esterification, pre-polycondensation, and final polycondensation reactions. The esterification reaction temperature was 200 °C, the pressure was 0.3 MPaG, and the stirring rate was 100 rpm. When the amount of water collected at the water outlet reached 90% of the theoretical water output, the esterification reaction was considered to be completed, and at this time, the total reaction time was 4 h. Subsequently, the esterification reaction liquid was subjected to a pre-polycondensation reaction, in which the pre-polycondensation reaction temperature was 230 °C, the reaction pressure was 5 KPaA, the stirring rate was 100 rpm, and the reaction time was 2 h. After the pre-polycondensation reaction was completed, the pre-polycondensation reaction liquid was subjected to a final polycondensation reaction, in which the final polycondensation reaction temperature was 250 °C, the reaction pressure was 20 PaA, the stirring rate was 100 rpm, and the reaction time was 0.1 h. After the reaction was completed, the polymer melt was transferred to water for cooling, stretching, pelletizing, and drying to obtain PTT chips.

[0085] Example 7

[0086] The catalyst III prepared in Example 3 was used for the preparation of polybutylene terephthalate (PBT), and the steps were as follows:

[0087] Terephthalic acid and 1,4-butanediol were charged into a polymerization kettle at a molar ratio of 1:1.8, and catalyst III with a titanium element content of 10 ppm was added to the polymerization kettle. At this time, the phosphorus element content was 15 ppm. The reaction materials were successively subjected to esterification, pre-polycondensation, and final polycondensation reactions. The esterification reaction temperature was 220 °C, the pressure was 0.2 MPaG, and the stirring rate was 150 rpm. When the amount of water collected at the water outlet reached 90% of the theoretical water output, the esterification reaction was considered to be completed, and at this time, the total reaction time was 3.5 h. Subsequently, the esterification reaction liquid was subjected to a pre-polycondensation reaction, in which the pre-polycondensation reaction temperature was 240 °C, the reaction pressure was 10 KPaA, the stirring rate was 150 rpm, and the reaction time was 1.5 h. After the pre-polycondensation reaction was completed, the pre-polycondensation reaction liquid was subjected to a final polycondensation reaction, in which the final polycondensation reaction temperature was 260 °C, the reaction pressure was 100 PaA, the stirring rate was 150 rpm, and the reaction time was 0.8 h. After the reaction was completed, the polymer melt was transferred to water for cooling, stretching, pelletizing, and drying to obtain PBT chips.

[0088] Example 8

[0089] The catalyst IV prepared in Example 4 was used for the preparation of poly(1,4-cyclohexanedimethylene terephthalate) (PCT), and the steps were as follows:

[0090] Terephthalic acid and 1,4-cyclohexanedimethanol were charged into a polymerization kettle at a molar ratio of 1:2, and catalyst IV with a titanium element content of 15 ppm was added to the polymerization kettle. At this time, the phosphorus element content was 22.5 ppm. The reaction materials were successively subjected to esterification, pre-polycondensation and final polycondensation reactions. The esterification reaction temperature was 240 °C, the pressure was 0 MPaG, and the stirring rate was 50 rpm. When the amount of water collected at the water outlet reached 90% of the theoretical water output, the esterification reaction was regarded as completed, and at this time, the total reaction time was 1 h. Subsequently, the esterification reaction liquid was subjected to pre-polycondensation reaction, in which the pre-polycondensation reaction temperature was 260 °C, the reaction pressure was 20 KPaA, the stirring rate was 50 rpm, and the reaction time was 2 h. After the pre-polycondensation reaction was completed, the pre-polycondensation reaction liquid was subjected to final polycondensation reaction, in which the final polycondensation reaction temperature was 300 °C, the reaction pressure was 80 PaA, the stirring rate was 50 rpm, and the reaction time was 1 h. After the reaction was completed, the polymer melt was transferred to water for cooling, stretching, pelletizing and drying to obtain PCT chips.

[0091] Example 9

[0092] The catalyst III prepared in Example 3 was used for the preparation of poly(butylene succinate) (PBS), including the following steps:

[0093] Succinic acid and butanediol were charged into a polymerization kettle at a molar ratio of 1:1.8, and catalyst III with a titanium element content of 15 ppm was added to the polymerization kettle. At this time, the phosphorus element content was 22.5 ppm. The reaction materials were successively subjected to esterification, pre-polycondensation and final polycondensation reactions. The esterification reaction temperature was 140 °C, the pressure was 0.1 MPaG, and the stirring rate was 120 rpm. When the amount of water collected at the water outlet reached 90% of the theoretical water output, the esterification reaction was regarded as completed, and at this time, the total reaction time was 2.5 h. Subsequently, the esterification reaction liquid was subjected to pre-polycondensation reaction, in which the pre-polycondensation reaction temperature was 180 °C, the reaction pressure was 5 KPaA, the stirring rate was 120 rpm, and the reaction time was 1.8 h. After the pre-polycondensation reaction was completed, the pre-polycondensation reaction liquid was subjected to final polycondensation reaction, in which the final polycondensation reaction temperature was 220 °C, the reaction pressure was 50 PaA, the stirring rate was 120 rpm, and the reaction time was 0.9 h. After the reaction was completed, the polymer melt was transferred to water for cooling, stretching, pelletizing and drying to obtain PBS chips.

[0094] Comparative Example 4

[0095] Compared with Example 5, in Comparative Example 1, the catalyst was changed to tetraethyl titanate with a titanium element content of 1 ppm, and triethyl phosphite was added as a stabilizer in the pre-polycondensation stage, and the phosphorus element content was 1.5 ppm. The other conditions were the same as those in Example 5.

[0096] Comparative Example 5

[0097] Compared with Example 6, in Comparative Example 2, the catalyst was changed to tetra-isopropyl titanate with a titanium element content of 5 ppm, and trimethyl phosphite was added as a stabilizer during the pre-polycondensation stage with a phosphorus element content of 7.5 ppm, and the other conditions were the same as those in Example 6.

[0098] Comparative Example 6

[0099] Compared with Example 7, in Comparative Example 3, the catalyst was changed to tetra-butyl titanate with a titanium element content of 10 ppm, and tri-propyl phosphite was added as a stabilizer during the pre-polycondensation stage with a phosphorus element content of 15 ppm, and the other conditions were the same as those in Example 7.

[0100] Comparative Example 7

[0101] Compared with Example 8, in Comparative Example 4, the catalyst was changed to tetra-butyl titanate with a titanium element content of 15 ppm, and triphenyl phosphite was added as a stabilizer during the pre-polycondensation stage with a phosphorus element content of 22.5 ppm, and the other conditions were the same as those in Example 8.

[0102] Comparative Example 8

[0103] Compared with Example 9, in Comparative Example 5, the catalyst was changed to tetra-butyl titanate with a titanium element content of 15 ppm, and tri-propyl phosphite was added as a stabilizer during the pre-polycondensation stage with a phosphorus element content of 22.5 ppm, and the other conditions were the same as those in Example 9.

[0104] The prepared polyesters of the above Examples 5 - 9 and Comparative Examples 4 - 8 were subjected to the measurement of intrinsic viscosity, carboxyl group content and color value b value, and the test results are shown in Table 1.

[0105] Table 1 Test Table of Intrinsic Viscosity, Carboxyl Group Content and Color Value b Value of Polyester

[0106]

[0107]

[0108] From the test results of the intrinsic viscosity, carboxyl group content and color value b value of Examples 5 - 9 and Comparative Examples 4 - 8, it can be seen that the catalytic stability and catalytic quality of the phosphorus-titanium polyester catalyst described in the present invention are superior to the combination of ordinary organic titanate catalysts and phosphite stabilizers. Specifically:

[0109] According to the test results of the polyester products in Examples 5-9 and Comparative Examples 4-8, compared with the combination composed of a common organic titanate catalyst and a phosphite stabilizer, the phosphorus-titanium polyester catalyst prepared by the present invention has a higher intrinsic viscosity, lower carboxyl content and lower b value of the color value for the polyester products prepared using the phosphorus-titanium polyester catalyst prepared by the present invention. This indicates that the phosphorus-titanium polyester catalyst provided by the present invention not only has excellent catalytic activity, but also can effectively inhibit side reactions such as thermal degradation and thermo-oxidative degradation during the catalytic process, reduce the carboxyl content in the polyester products, improve the yellowing problem commonly existing in the polyester products prepared by titanium-based catalysts, and enhance the quality of the titanium-based polyester products.

[0110] According to the implementation results of Example 9, the phosphorus-titanium polyester catalyst prepared by the present invention not only can be used for common terephthalic acid-based polyesters, but also has excellent catalytic activity for aliphatic polyesters, indicating that this series of catalysts can be used to prepare different types of polyester products.

[0111] It should be noted that the above content is a further detailed description of the present invention in combination with specific implementation manners, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple improvements and retouches can still be made, and all of them should be regarded as belonging to the protection scope of the present invention.

Claims

1. A phosphorus-titanium polyester catalyst, characterized in that, The structural general formula of the phosphorus-titanium polyester catalyst is as follows: In the formula, R1 is selected from any one of a hydroxyl group, a C1-C12 aliphatic alkoxy group, or an aromatic alkoxy group; R2 is selected from a C2-C12 aliphatic alkyl group.

2. A preparation method of the phosphorus-titanium polyester catalyst as described in claim 1, characterized in that, It includes the following steps: S1: Under the protection of an inert gas, add a dihalophosphite to a mixed solution of an aliphatic diol and an acid-binding agent, stir at 20-60 °C for 5-10 h, filter and distill under reduced pressure to obtain a bis-diol-substituted phosphite; S2: Under the protection of an inert gas, dissolve an organic titanate in an organic solvent, then add the bis-diol-substituted phosphite described in step S1, stir at 20-60 °C for 3-8 h, filter, wash, and dry to obtain a solid product, the phosphorus-titanium polyester catalyst.

3. The preparation method of the phosphorus-titanium polyester catalyst according to claim 2, characterized in that, The structural general formula of the dihalophosphite described in step S1 is wherein R1 is selected from any one of a hydroxyl group, a C1-C12 aliphatic alkoxy group or an aromatic alkoxy group, and X is selected from any one of halogen elements.

4. The preparation method of the phosphorus-titanium polyester catalyst according to claim 2, wherein, The aliphatic diol described in step S1 is one or more of C2-C12 aliphatic diols.

5. The preparation method of the phosphorus-titanium polyester catalyst according to claim 2, wherein, The acid-binding agent described in step S1 is one or more of triethylamine, pyridine, and 4-dimethylaminopyridine.

6. The preparation method of the phosphorus-titanium polyester catalyst according to claim 2, wherein The molar ratio of the dihalophosphite, aliphatic diol, and acid-binding agent described in step S1 is 1:(2.2-5):(2.2-3).

7. The preparation method of the phosphorus-titanium polyester catalyst according to claim 2, wherein The organic titanate described in step S2 is at least one of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, alkoxy phthalate, diisopropyl bis(acetylacetonato)titanate, tetra-tert-butyl phthalate, and alkyl phthalate; And / or, the organic solvent described in step S2 is an anhydrous solvent capable of dissolving the organic phthalate.

8. The preparation method of the phosphorus-titanium polyester catalyst according to claim 2, characterized in that, The molar ratio of the bis-diol-substituted phosphite to the organic titanate described in step S2 is (2.1-2.5):

1.

9. Use of a phosphorus-titanium polyester catalyst prepared by the method according to claim 1 or prepared by the preparation method according to any one of claims 2 to 8 in the preparation of polyester, characterized in that, Using a dibasic acid and a diol as reaction monomers, carry out an esterification reaction, a pre-polycondensation reaction, and a final polycondensation reaction in sequence under the action of the phosphorus-titanium polyester catalyst; Among them, the dibasic acid is one or several of aliphatic, cycloaliphatic, or aromatic dibasic acids with a carbon number not exceeding 10; And / or, the diol is one or several of aliphatic, cycloaliphatic, or aromatic diols with a carbon number not exceeding 10; And / or, the molar ratio of the dibasic acid to the diol is 1:(1.2-2.0); And / or, the usage amount of the phosphorus-titanium polyester catalyst is based on the mass of the theoretically generated polyester, and the mass ratio of titanium atoms is 1-20 ppm.

10. The application according to claim 9, wherein, The temperature of the esterification reaction is 140-240 °C, the pressure is 0-0.5 MPaG, the stirring rate is 50-200 rpm, and the reaction time is 1-4 h; And / or, the temperature of the pre-polycondensation reaction is 180-260 °C, the pressure is 5-50 KPaA, the stirring rate is 50-200 rpm, and the reaction time is 0.5-2 h; And / or, the temperature of the final polycondensation reaction is 220-300 °C, the pressure is 20-200 PaA, the stirring rate is 50-200 rpm, and the reaction time is 0.1-1 h.

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