Use of compounds as catalysts in the preparation of polyesters by esterification polymerization, polyesters and methods of preparation and use thereof

Abstract

The present application relates to the technical field of catalysts for polyester synthesis, and particularly relates to application of a compound as a catalyst in esterification polymerization for preparing polyester, polyester and a preparation method and application thereof.The structure of the compound is shown as formula (I), wherein R1 and R2 are each independently selected from *-R4, R4 is selected from a substituted or unsubstituted aromatic group, a substituted or unsubstituted cyclic alkyl group or a substituted or unsubstituted chain alkyl group, n2 is an integer between 1 and 12; R3 is selected from cycloalkenylene or alkylene; Y is selected from *=X, X is S or O; n1 is 1 or 2; * represents a connection site.The compound with the specific structure in the present application can play the advantage of high activity in the process of esterification polymerization for preparing polyester.

Description

Technical Field

[0001] This invention relates to the field of catalysts for polyester synthesis, specifically to the application of a compound as a catalyst in the esterification polymerization of polyester, polyester and its preparation method and application. Background Technology

[0002] Plasticizers are substances added to polymer materials to increase their plasticity. The use of plasticizers can improve the properties of polymer materials, reduce production costs, and increase production efficiency. The main function of plasticizers is to weaken the secondary valence bonds between resin molecules, increase the mobility of resin molecular bonds, reduce the crystallinity of resin molecules, increase the plasticity of resin molecules, and enhance their flexibility and ease of processing. Currently, the most widely used plasticizers in industry are those containing phthalates or DOA. Although their plasticizing effect is significant, they are prone to migration, affecting the performance and service life of the products. Furthermore, when plasticizers migrate outward from the product, they can also cause harm to human health and the ecological environment.

[0003] Environmentally friendly polyester plasticizers are chemicals used to improve the properties of plastics. They possess environmentally friendly properties, reducing the environmental pollution problems that traditional plasticizers may cause. These plasticizers are commonly used in polyester plastics, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). They improve the processing performance of plastics and the physical properties of the final product by increasing the flexibility of the polymer chains. Environmentally friendly polyester plasticizers reduce the use of harmful substances during the production process, meeting current requirements for environmental protection and sustainable development.

[0004] Esterification polymerization is a chemical reaction process used to synthesize polyester plasticizers. In esterification polymerization, the reaction of an acid and an alcohol typically involves the formation of esters and water. When the reaction proceeds under polymerization conditions, the esterification of monomers occurs continuously, forming long-chain polyester molecules. This process can be achieved through polycondensation, in which monomer molecules lose smaller molecules (such as water) to form polymer chains. Esterification polymerization is often carried out in the presence of a catalyst to achieve the esterification and polymerization process. Currently, metal-based catalysts, such as titanium-based catalysts, are commonly used. However, the catalyst is usually replenished after the reaction and separated from the polymerization system, leaving residual metal ions in the polyester. This can affect the performance of the final polymer product and result in polyesters with high color intensity. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of metal residue and high color of polyester prepared by esterification polymerization in the prior art. In the research process, a metal-free compound was discovered that can be used for esterification polymerization to prepare polyester and also has excellent catalytic activity.

[0006] Based on this, the present invention provides, in one aspect, the application of a compound as a catalyst in the esterification polymerization preparation of polyester, the structure of which is shown in formula (I).

[0007]

[0008] Among them, R1 and R2 are each independently selected. R4 is selected from substituted or unsubstituted aromatic groups, substituted or unsubstituted cyclic alkyl groups, and substituted or unsubstituted chain alkyl groups; n2 is an integer between 1 and 12; R3 is selected from cycloene alkenyl groups or alkylene groups; Y is selected from... X represents S or O; n1 represents 1 or 2; * indicates a connection site.

[0009] A second aspect of the present invention provides a method for preparing a polyester, the method comprising: esterifying and polymerizing a reaction mixture comprising at least one dicarboxylic acid and at least one diol in the presence of a catalyst of the compound represented by formula (I) of the first aspect of the present invention.

[0010] The third aspect of the present invention provides a polyester prepared by the preparation method described in the second aspect of the present invention.

[0011] The fourth aspect of the present invention provides the use of the polyester described herein in plasticizers.

[0012] Through the above technical solution, the catalysts used in the existing esterification polymerization to prepare polyester are generally metal-based catalysts, such as tetrabutyl titanate or stannous octoate. However, metal-based catalysts can cause reverse reactions in the esterification polymerization process. The inventors of this invention unexpectedly discovered that the compound with a specific structure in this invention can exert a high activity advantage in the esterification polymerization process to prepare polyester. In addition, the compound does not contain trace metals, and the final polyester product does not contain trace metals either. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] The first aspect of this invention provides the application of a compound as a catalyst in the esterification polymerization preparation of polyester, the structure of which is shown in formula (I).

[0015]

[0016] Among them, R1 and R2 are each independently selected from *-R4 R4 is selected from substituted or unsubstituted aromatic groups, substituted or unsubstituted cyclic alkyl groups, and substituted or unsubstituted chain alkyl groups; n2 is an integer between 1 and 12; R3 is selected from cycloene alkenyl groups or alkylene groups; Y is selected from... X represents S or O; n1 represents 1 or 2; * indicates a connection site.

[0017] Existing catalysts used in the esterification polymerization of polyester are generally metal-based catalysts, such as tetrabutyl titanate or stannous octoate. However, metal-based catalysts can cause reverse reactions in the esterification polymerization process. The inventors of this invention unexpectedly discovered that using compounds with a specific structure in this invention can exert a high activity advantage in the esterification polymerization of polyester. In addition, this compound does not contain trace amounts of metal, and the final polyester product also does not contain trace amounts of metal.

[0018] According to the present invention, R4 is selected from substituted or substituted aromatic groups, substituted or unsubstituted cyclic alkyl groups, and substituted or unsubstituted chain alkyl groups. The substituted aromatic group is one or more hydrogen atoms on the aromatic group that are replaced by a substituent. The substituted cyclic alkyl group and the substituted alkyl group also have corresponding definitions. As long as the purpose of the present invention can be achieved, the type of substituent is not particularly limited. In a preferred embodiment of the present invention, the substituents on the aromatic group, cyclic alkyl group and chain alkyl group in R4 are each independently hydroxyl, trifluoromethyl, and methyl, preferably each independently hydroxyl and trifluoromethyl.

[0019] According to the present invention, as long as the purpose of the present invention can be achieved, there is no particular limitation on the number of substituents on the aromatic group, cyclic alkyl group and chain alkyl group in R4. In a preferred embodiment of the present invention, the number of substituents on the phenyl group, cyclohexyl group and alkyl group is independently 0-5. When it is 0, it is indicated as "unsubstituted", that is, it does not contain substituents. For example, it is 0, 1, 2, 3, 4 or 5, preferably 0-2.

[0020] According to a preferred embodiment of the present invention, R4 is selected from substituted or unsubstituted C6-C12 aromatic groups and substituted or unsubstituted C4-C8 cyclic alkyl groups. The catalysts of the aforementioned embodiments exhibit superior catalytic activity in the preparation of polyesters.

[0021] The aromatic groups that can be listed in this invention include phenyl, biphenyl, etc., which are C6-C12 groups; the cyclic alkyl groups that can be listed in this invention include cyclobutyl, cyclopentyl, cyclohexyl, etc., which are C4-C8 groups.

[0022] According to a preferred embodiment of the present invention, n2 is an integer between 2 and 5, for example, 2, 3, 4, or 5. When it is 2, it indicates that the corresponding group is ethylidene; when it is 3, it indicates that the corresponding group is propylidene; when it is 4, it indicates that the corresponding group is butylidene; and when it is 5, it indicates that the corresponding group is pentylidene.

[0023] According to a preferred embodiment of the present invention, R1 is selected from *-R4, and R2 is selected from...

[0024] According to a preferred embodiment of the present invention, R1 is selected from *-R4, and R2 is selected from...

[0025] According to a preferred embodiment of the present invention, R1 is selected from *-R4, and R2 is selected from...

[0026] In this invention, the two connections in the compound represented by formula (I) refer to the two N atoms in formula (I) being connected by an R3 group (cycloene-alkenyl or alkylene), wherein one or two H atoms on R3 are replaced by Y. According to a preferred embodiment of the invention, R3 is selected from C3-C4. 14 Cycloalkenyl or C1-C5 alkylene groups.

[0027] C3-C can be listed in this invention. 14 The cycloalkylene groups include cycloalkylene propenylene, cycloalkylene butenylene, cycloalkylene pentenylene, 3-methylcycloalkylene pentenylene, 2,3-dimethylcycloalkylene pentenylene, cycloalkylene hexenylene, cycloalkyl heptenylene, cycloalkyl octenylene, etc., and preferably R3 is selected from C4-C6 cycloalkylene groups.

[0028] The C1-C5 alkylene groups that can be listed in this invention include methylene, ethylene, propylene, butylene, and pentylene, with R3 preferably selected from C1-C2 alkylene groups.

[0029] According to a preferred embodiment of the present invention, X is S.

[0030] According to a preferred embodiment of the present invention, the structure of the compound is shown in one of formulas (I1)-(I7), and the structure of the preferred compound is shown in one of formulas (I1)-(I6):

[0031]

[0032]

[0033] According to the present invention, in one embodiment, the structure of the compound is shown in formula (I1); in one embodiment, the structure of the compound is shown in formula (I2); in one embodiment, the structure of the compound is shown in formula (I3); in one embodiment, the structure of the compound is shown in formula (I4); in one embodiment, the structure of the compound is shown in formula (I5); and in one embodiment, the structure of the compound is shown in formula (I6).

[0034] A second aspect of the present invention provides a method for preparing a polyester, the method comprising: esterifying and polymerizing a reaction mixture comprising at least one dicarboxylic acid and at least one diol in the presence of a catalyst of the compound represented by formula (I) of the first aspect of the present invention.

[0035] In this invention, the compounds of this invention are used to prepare polyester. The preparation method of the synthesized polyester is simple, the process is controllable, and it is non-toxic, harmless, green and environmentally friendly. The polyester prepared does not contain trace metal elements and has the advantages of low color.

[0036] According to the present invention, the amount of catalyst used is sufficient to allow the esterification polymerization reaction to proceed sufficiently. In a preferred embodiment, the molar ratio of the catalyst to the dicarboxylic acid is (0.5-5) × 10⁻⁶. -5 :1, preferably (2-3)×10 -5 :1.

[0037] According to a preferred embodiment of the present invention, the molar ratio of the diol to the dicarboxylic acid is (0.1-2):1, preferably (0.8-1.5):1.

[0038] In the preparation of polyester, to increase the polyester's aging resistance or other properties, appropriate additives, such as antioxidants, may be added as needed. In one embodiment, the reaction mixture further contains an antioxidant, preferably with a molar ratio of (0.8-1.2)×10⁻⁶ to the dicarboxylic acid. -3 :1.

[0039] In this invention, the appropriate dicarboxylic acid can be selected according to the type of polyester, preferably an aliphatic dicarboxylic acid.

[0040] According to a preferred embodiment of the present invention, the dicarboxylic acid is selected from C2-C. 12 The aliphatic dicarboxylic acid. Preferably selected from at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, and sebacic acid. Adipic acid is used as an example in this invention to illustrate its advantages, but the invention is not limited thereto.

[0041] According to the present invention, the appropriate diol can be selected according to the type of polyester required. Preferably, the diol is selected from aliphatic diols.

[0042] According to a preferred embodiment of the present invention, the diol is selected from C2-C. 12 The aliphatic diol is preferably selected from at least one of ethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and 2,2-dimethyl-1,3-propanediol. 1,2-propanediol and / or diethylene glycol are used as examples to illustrate the advantages of the invention, but the invention is not limited thereto.

[0043] According to a preferred embodiment of the present invention, the esterification polymerization reaction includes sequentially performed pressurized esterification polymerization and negative pressure esterification polymerization.

[0044] In this invention, pressurized esterification polymerization refers to a polymerization reaction carried out under a certain pressure. Preferred conditions for pressurized esterification polymerization include: conducting the reaction under an inert atmosphere, wherein the inert atmosphere is a conventional inert atmosphere in the art, such as nitrogen; that is, the air in the reactor is replaced with an inert gas before the reaction. Preferred conditions for pressurized esterification polymerization also include: a reaction temperature of 100-250℃, preferably 150-180℃. The endpoint of the pressurized reaction is not specifically defined; when the set reaction temperature is reached, the reaction system has a certain pressure, generally 0.2-0.3 MPa. The reaction is carried out at this temperature. During the reaction, when the pressure reaches approximately 0 MPa, the pressurized esterification polymerization is stopped and replaced with negative pressure esterification polymerization. The reaction time is generally 1-2 hours.

[0045] In this invention, negative pressure esterification polymerization refers to polymerization reaction carried out under a certain vacuum. Preferred conditions for negative pressure esterification polymerization include: reaction temperature of 150-300℃, preferably 180-250℃; preferred conditions for negative pressure esterification polymerization include: vacuum degree of 50-150Pa; preferred conditions for negative pressure esterification polymerization include: reaction endpoint of acid value below 5mg KOH / g.

[0046] The third aspect of the present invention provides a polyester prepared by the preparation method described in the second aspect of the present invention.

[0047] The polyester in this invention has a low chromaticity. Preferably, the chromaticity of the polyester is not higher than 35, and more preferably 20-30.

[0048] According to the present invention, polyester can be used in different fields as needed, and the fourth aspect of the present invention provides the application of the polyester described herein in plasticizers.

[0049] According to the present invention, preferably, the polyester is used as a plasticizer in PVC.

[0050] The plasticizer exhibits good compatibility with polyvinyl chloride (PVC), has a light color, and possesses suitable viscosity, density, acid value, and other properties for processing. When applied to PVC, this plasticizer produces plasticized PVC with good thermal stability, high elongation at break, and significantly improved plasticizing efficiency.

[0051] The present invention will be described in detail below through embodiments. The following embodiments include:

[0052] The acid value of the polyester was obtained by ASTM D664-18e2 test;

[0053] The dynamic viscosity of the polyester was obtained by testing according to ASTM D445-23;

[0054] Colorimetric analysis was performed according to ASTM D1500-12 (2017).

[0055] The number-average molecular weight was obtained by testing according to GB / T 14190-93 3.

[0056] Example 1

[0057] Preparation of polyester:

[0058] (1): 1,2-Propanediol, adipic acid, antioxidant 168, and catalyst were added to the reactor in a solid-to-liquid ratio; wherein the molar ratio of 1,2-propanediol to adipic acid was 1.2:1; and the molar ratio of antioxidant 168 to adipic acid was 1.0 × 10⁻⁶. -3 :1; The molar ratio of catalyst to adipic acid is 2.5 × 10⁻⁶. -5 :1; The catalyst is (E)-2-(2-hydroxybenzylmethyl)-N-phenylhydrazine-1-amide (CAS No. 91991-03-6);

[0059] (2): Nitrogen gas is introduced into the reactor to replace the air three times, and then nitrogen gas is introduced to 0.1 MPa;

[0060] (3): Pressurized esterification polymerization, the reactor is heated, and the pressure inside the reactor is 0.2MPa after the temperature inside the reactor reaches 160℃. When the pressure inside the reactor is 0MPa, the pressurized esterification polymerization reaction ends.

[0061] (4): Negative pressure esterification polymerization, the temperature inside the reactor is 205℃ and the vacuum degree is 100Pa, and the negative pressure esterification reaction is carried out;

[0062] (5): Discharge the material. When the acid value of the reaction system is lower than 5 mg KOH / g, cool down and discharge the material to obtain polyester A.

[0063] The characterization of polyester A and the time taken for negative pressure esterification polymerization are shown in Table 1.

[0064] Example 2

[0065] Preparation of polyester:

[0066] (1): 1,2-Propanediol, adipic acid, antioxidant 168, and catalyst were added to the reactor in a solid-to-liquid ratio; wherein the molar ratio of 1,2-propanediol to adipic acid was 1.5:1; and the molar ratio of antioxidant 168 to adipic acid was 1.2 × 10⁻⁶. -3 :1; 3×10 of catalyst and adipic acid -5 :1; The catalyst is (E)-2-(4-hydroxybenzylmethyl)-N-phenylhydrazine-1-thioamide (CAS No. 76572-74-2);

[0067] (2): Nitrogen gas is introduced into the reactor to replace the air three times, and then nitrogen gas is introduced to 0.1 MPa;

[0068] (3): Pressurized esterification polymerization: The reactor is heated to 170℃ and the pressure inside the reactor is 0.21MPa. When the pressure inside the reactor is 0MPa, the pressurized esterification polymerization reaction ends.

[0069] (4): Negative pressure esterification polymerization, the temperature inside the reactor is 210℃ and the vacuum degree is 100Pa, and the negative pressure esterification reaction is carried out;

[0070] (5): Discharge the material. When the acid value of the reaction system is lower than 5 mg KOH / g, cool down and discharge the material to obtain polyester B.

[0071] The characterization of polyester B and the time taken for negative pressure esterification polymerization are shown in Table 1.

[0072] Example 3

[0073] (1): Diethylene glycol, adipic acid, antioxidant 168, and catalyst were added to the reactor in a solid-to-liquid ratio; wherein the molar ratio of diethylene glycol to adipic acid was 1:1; and the molar ratio of antioxidant 168 to adipic acid was 1.0 × 10⁻⁶. -3 :1; 2.5 × 10⁻⁶ for catalyst and adipic acid -5 :1; The catalyst is 1-(3,5-bis(trifluoromethyl)phenyl)-3-(2-(diphenylphosphino)ethyl)urea (CAS No. 1938090-75-5);

[0074] (2): Nitrogen gas is introduced into the reactor to replace the air three times, and then nitrogen gas is introduced to 0.1 MPa;

[0075] (3): Pressurized esterification polymerization, the reactor is heated, and the pressure inside the reactor is 0.21 MPa after the temperature inside the reactor reaches 170℃. When the pressure inside the reactor is 0 MPa, the pressurized esterification polymerization reaction ends.

[0076] (4): Negative pressure esterification polymerization, the temperature inside the reactor is 205℃ and the vacuum degree is 100Pa, and the negative pressure esterification reaction is carried out;

[0077] (5): Discharge the material. When the acid value of the reaction system is lower than 5 mg KOH / g, cool down and discharge the material to obtain polyester C.

[0078] The characterization of polyester C and the time taken for negative pressure esterification polymerization are shown in Table 1.

[0079] Example 4

[0080] Preparation of polyester:

[0081] (1): Diethylene glycol, adipic acid, antioxidant 168, and catalyst were added to the reactor in a solid-to-liquid ratio; wherein the molar ratio of diethylene glycol to adipic acid was 0.8:1; and the molar ratio of antioxidant 168 to adipic acid was 0.9 × 10⁻⁶. -3 :1; 2.2 × 10⁻⁶ for catalyst and adipic acid -5 :1; The catalyst is 3-((3,5-bis(trifluoromethyl)phenyl)amino)-4-((3-hydroxyphenyl)amino)cyclobut-3-ene–1,2-dione (CAS No. 2490231-69-9);

[0082] (2): Nitrogen gas is introduced into the reactor to replace the air three times, and then nitrogen gas is introduced to 0.1 MPa;

[0083] (3): Pressurized esterification polymerization, the reactor is heated, and the pressure inside the reactor is 0.19MPa after the temperature inside the reactor reaches 165℃. When the pressure inside the reactor is 0MPa, the pressurized esterification polymerization reaction ends.

[0084] (4): Negative pressure esterification polymerization, the temperature inside the reactor is 215℃ and the vacuum degree is 100Pa, and the negative pressure esterification reaction is carried out.

[0085] (5): Discharge the material. When the acid value of the reaction system is lower than 5 mg KOH / g, cool down and discharge the material to obtain polyester D.

[0086] The characterization of polyester D and the time taken for negative pressure esterification polymerization are shown in Table 1.

[0087] Example 5

[0088] (1): Diethylene glycol, adipic acid, antioxidant 168, and catalyst were added to the reactor in a solid-to-liquid ratio; wherein the molar ratio of diethylene glycol to adipic acid was 1:1; and the molar ratio of antioxidant 168 to adipic acid was 1.0 × 10⁻⁶. -3 :1; 2.5 × 10⁻⁶ for catalyst and adipic acid -5 :1; The catalyst is 1-cyclohexyl-3-(2-(diphenylphosphino)ethyl)urea (CAS No. 2892082-04-9);

[0089] (2): Nitrogen gas is introduced into the reactor to replace the air three times, and then nitrogen gas is introduced to 0.1 MPa;

[0090] (3): Pressurized esterification polymerization, the reactor is heated, and the pressure inside the reactor is 0.21 MPa after the temperature inside the reactor reaches 170℃. When the pressure inside the reactor is 0 MPa, the pressurized esterification polymerization reaction ends.

[0091] (4): Negative pressure esterification polymerization, the temperature inside the reactor is 205℃ and the vacuum degree is 100Pa, and the negative pressure esterification reaction is carried out;

[0092] (5): Discharge the material. When the acid value of the reaction system is lower than 5 mg KOH / g, cool down and discharge the material to obtain polyester C.

[0093] The characterization of polyester E and the time taken for negative pressure esterification polymerization are shown in Table 1.

[0094] Example 6

[0095] Preparation of polyester:

[0096] (1): Diethylene glycol, adipic acid, antioxidant 168, and catalyst were added to the reactor in a solid-to-liquid ratio; wherein the molar ratio of diethylene glycol to adipic acid was 1:1; and the molar ratio of antioxidant 168 to adipic acid was 1.0 × 10⁻⁶. -3 :1; 2.5 × 10⁻⁶ for catalyst and adipic acid -5 :1; The catalyst is 1-(2-(diphenylphosphino)ethyl)-3-phenylthiourea (CAS No. 261177-72-4);

[0097] (2): Nitrogen gas is introduced into the reactor to replace the air three times, and then nitrogen gas is introduced to 0.1 MPa;

[0098] (3): Pressurized esterification polymerization, the reactor is heated, and the pressure inside the reactor is 0.21 MPa after the temperature inside the reactor reaches 170℃. When the pressure inside the reactor is 0 MPa, the pressurized esterification polymerization reaction ends.

[0099] (4): Negative pressure esterification polymerization, the temperature inside the reactor is 205℃ and the vacuum degree is 100Pa, and the negative pressure esterification reaction is carried out;

[0100] (5): Discharge the material. When the acid value of the reaction system is lower than 5 mg KOH / g, cool down and discharge the material to obtain polyester C.

[0101] The characterization of polyester F and the time taken for negative pressure esterification polymerization are shown in Table 1.

[0102] Example 7

[0103] Preparation of polyester:

[0104] (1): 1,2-Propanediol, adipic acid, antioxidant 168, and catalyst were added to the reactor in a solid-to-liquid ratio; wherein the molar ratio of 1,2-propanediol to adipic acid was 1.2:1; and the molar ratio of antioxidant 168 to adipic acid was 1.0 × 10⁻⁶. -3 :1; The molar ratio of catalyst to adipic acid is 2.5 × 10⁻⁶. -5 :1; The catalyst is N-butyl-2-[(2-hydroxyphenyl)methylene]hydrazinoamide (CAS No. 728881-88-7);

[0105] (2): Nitrogen gas is introduced into the reactor to replace the air three times, and then nitrogen gas is introduced to 0.1 MPa;

[0106] (3): Pressurized esterification polymerization: After the reactor is heated to 160°C, the pressure inside the reactor is 0.2 MPa. When the pressure inside the reactor is 0 MPa, the pressurized esterification polymerization reaction ends.

[0107] (4): Negative pressure esterification polymerization, the temperature inside the reactor is 205℃ and the vacuum degree is 100Pa, and the negative pressure esterification reaction is carried out;

[0108] (5): Discharge the material. When the acid value of the reaction system is lower than 5 mg KOH / g, cool down and discharge the material to obtain polyester A.

[0109] The characterization of polyester G and the time taken for negative pressure esterification polymerization are shown in Table 1.

[0110] Comparative Example 1

[0111] The method is the same as in Example 1, except that:

[0112] The catalyst in Example 1 was replaced with titanium butoxide, and the molar ratio of titanium butoxide (based on titanium) to adipic acid was 2.5 × 10⁻⁶. -5 :1.

[0113] Comparative Example 2

[0114] The method is the same as in Example 2, except that:

[0115] The catalyst in Example 2 was replaced with tetrabutyl titanate, and the molar ratio of tetrabutyl titanate (based on titanium) to adipic acid was 3 × 10⁻⁶. -5 :1.

[0116] Comparative Example 3

[0117] The method is the same as in Example 3, except that:

[0118] The catalyst in Example 3 was replaced with tetraisopropyl titanate, and the molar ratio of tetrabutyl titanate (based on titanium) to adipic acid was 2.5 × 10⁻⁶. -5 :1.

[0119] Comparative Example 4

[0120] The method is the same as in Example 4, except that:

[0121] The catalyst in Example 4 was replaced with titanium glycolate, and the molar ratio of titanium glycolate (based on titanium) to adipic acid was 2.2 × 10⁻⁶. -5 :1.

[0122] Table 1

[0123]

[0124] The results in Table 1 show that the compounds of the present invention do not contain metal ions and can be used for esterification polymerization to synthesize polyester products. The resulting polyester products not only have excellent catalytic activity, but also have low color.

[0125] Application examples

[0126] The elongation at break was obtained by testing according to GB-T 14344-2022;

[0127] The tensile strength was obtained by testing according to GB-T 14344-2022.

[0128] 55 parts by weight of polyester and DOP from Examples 1-3 were added to 100 parts by weight of PVC resin (brand name SG-3) and then melt-blended to obtain plasticized PVC.

[0129] The properties of the obtained plasticized PVC are shown in Table 2.

[0130] Table 2

[0131] No. % Elongation at break Tensile strength / MPa Example 1 473.7 22.1 Example 2 626.9 20.1 Example 3 572.6 33.2 DOP 357 17.5

[0132] As can be seen from the test results in Table 2, compared with DOP plasticizer, polyester obtained by esterification polymerization using the compound of this invention as a catalyst has better compatibility with PVC resin and has superior plasticizing performance.

[0133] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. The application of a compound as a catalyst in the esterification polymerization preparation of polyester, characterized in that, The structure of the compound is shown in formula (I). Among them, R1 and R2 are each independently selected from *-R4, R4 is selected from substituted or unsubstituted aromatic groups, substituted or unsubstituted cyclic alkyl groups, and substituted or unsubstituted chain alkyl groups, and n2 is an integer between 1 and 12; R3 is selected from cycloene-olefin or alkylene-olefin; Y is selected from *=x, and X is S or O; n1 is 1 or 2; * indicates a connection point.

2. The application according to claim 1, wherein, In R4, the substituents on the aromatic group, cyclic alkyl group, and chain alkyl group are each independently hydroxyl, trifluoromethyl, and methyl, preferably each independently hydroxyl and trifluoromethyl; and / or In R4, the number of substituents on the aromatic group, cyclic alkyl group, and chain alkyl group is independently 0-5, preferably 0-2; and / or R4 is selected from substituted or unsubstituted C6-C12 aromatic groups and substituted or unsubstituted C4-C8 cyclic alkyl groups.

3. The application according to claim 1 or 2, wherein, n2 is an integer between 2 and 5; and / or R1 is selected from *-R4, R2 is selected from 4. The application according to any one of claims 1-3, wherein, R3 is selected from C3-C 14 Cycloalkenyl or C1-C5 alkylene groups, preferably selected from C4-C6 cycloalkenyl or C1-C2 alkylene groups; and / or X is S.

5. The application according to any one of claims 1-4, wherein, The structure of the compound is shown in one of formulas (I1)-(I7), and the structure of the preferred compound is shown in one of formulas (I1)-(I6):

6. A method for preparing polyester, characterized in that, The preparation method includes: An esterification polymerization reaction comprising at least one dicarboxylic acid and at least one diol is carried out in the presence of a catalyst of the compound of formula (I) according to any one of claims 1-5.

7. The preparation method according to claim 6, wherein, The molar ratio of the catalyst to the dicarboxylic acid is (0.5-5)×10. -5 :1, preferably (2-3)×10 -5 : 1; and / or The molar ratio of the diol to the dicarboxylic acid is (0.1-2):1, preferably (0.8-1.5):1; and / or The reaction mixture also contains an antioxidant, preferably in a molar ratio of (0.8-1.2)×10⁻⁶ to the dicarboxylic acid. -3 :1; and / or The dicarboxylic acid is selected from aliphatic dicarboxylic acids, preferably from C2-C. 12 Aliphatic dicarboxylic acids; Preferably, the C2-C 12 The aliphatic dicarboxylic acid is selected from at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, and sebacic acid, preferably adipic acid; and / or The diol is selected from aliphatic diols, preferably from C2-C. 12 aliphatic diols; Preferably, the C2-C 12 The aliphatic diol is selected from at least one of ethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and 2,2-dimethyl-1,3-propanediol, preferably 1,2-propanediol and / or diethylene glycol.

8. The preparation method according to claim 6 or 7, wherein, The esterification polymerization reaction includes sequentially performed pressurized esterification polymerization and negative pressure esterification polymerization; Preferably, The conditions for the pressurized esterification polymerization include: being carried out under an inert atmosphere and / or, with a reaction temperature of 100-250°C, preferably 150-180°C; and / or The conditions for the negative pressure esterification polymerization include: a reaction temperature of 150-300℃, preferably 180-250℃ and / or, a vacuum degree of 50-150Pa and / or, and a reaction endpoint of acid value below 5mg KOH / g.

9. A polyester prepared by the preparation method according to any one of claims 6-8; Preferably, the color of the polyester is not higher than 35, and more preferably 20-30.

10. The use of the polyester of claim 9 in a plasticizer; Preferably, the polyester is used as a plasticizer in PVC.

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