A method for preparing low melting point polyester or copolyester by synthetic method

Abstract

The present application relates to the technical field of polymer synthesis, and specifically discloses a method for preparing low-melting-point polyester or copolyester by synthesis; a method for preparing low-melting-point polyester or copolyester by synthesis, comprising the following specific steps: mixing dibasic acid and diol as raw materials with a composite catalyst and heating, obtaining an esterified product after esterification reaction, mixing the esterified product with terminal hydroxyl silicone oil and a modifier for polycondensation reaction to obtain a melt, extruding the melt through an inert gas, and granulating to obtain the low-melting-point polyester or copolyester; the modifier comprises ethylenediamine and epoxy resin; the epoxy resin and ethylenediamine can change the molecular structure of the polyester, and the introduction of the silicon-containing component can reduce the structural stability of the polyester, thereby reducing the melting point of the polyester.

Description

Technical Field

[0001] The present application relates to the technical field of polymer synthesis, and in particular to a method for preparing low-melting-point polyester or copolyester by synthesis. Background Art

[0002] Polyester or copolyester is an important part of modern polymer material science and is widely used in textile, packaging, electronics and other fields. These materials are favored for their excellent physical properties and chemical stability. During the synthesis or processing of high melting point polymers, as the temperature increases, the side reactions increase, which affects the quality and increases energy consumption. In order to avoid the side reactions caused by high temperature polymerization, the molecular weight of the polymer is often increased by solid phase viscosity increase. For example, PET polymer particles are generally crystallized at about 140-180℃ for about 40min-1h, then preheated to about 180-215℃, kept at a constant temperature for 1-4h, and then solid-state polymerized at about 200-220℃ for about 8-12h to increase their molecular weight.

[0003] The solid phase viscosity increase is accompanied by an increase in crystallinity, which can reach 45%. Such a high crystallinity and high melting point of the polymer are disadvantages in the extrusion zone of the molding process, because as the melting point of the polymer increases, more energy is required to melt the polymer particles. Therefore, high melting point polyesters or copolyesters require higher temperatures during processing and use, which not only increases energy consumption, but also increases production costs. Summary of the invention

[0004] In order to lower the melting point of polyester or copolyester, the present application provides a method for synthesizing low-melting-point polyester or copolyester.

[0005] The present application provides a method for preparing low-melting-point polyester or copolyester by a synthetic method, which adopts the following technical scheme: A method for preparing low-melting-point polyester or copolyester by a synthetic method, comprising the following specific steps: mixing a dibasic acid and a diol as raw materials with a composite catalyst and heating them, obtaining an esterified product after an esterification reaction, mixing the esterified product with terminal hydroxyl silicone oil and a modifier for a condensation reaction to obtain a melt, extruding the melt through an inert gas, and granulating to obtain a low-melting-point polyester or copolyester; the modifier comprises ethylenediamine and an epoxy resin.

[0006] By adopting the above technical scheme, in the polycondensation reaction, the esterification product continues to undergo polymerization reaction under the action of the catalyst and the modifier to generate a longer polyester chain. The addition of the modifier can change the molecular structure of the polyester, thereby reducing the melting point of the polyester and the copolyester. The introduction of terminal hydroxyl silicone oil into the polyester molecular chain can reduce the structural regularity of the polyester and the copolyester, thereby reducing the melting point of the polyester and the copolyester. At the same time, the introduction of silicon-containing components can improve the carbon residue and impact strength of the polyester and the copolyester. Epoxy resin and ethylenediamine can react with the carboxyl or hydroxyl group in the polyester chain to form a new chemical bond, destroy the regularity of the polyester molecule, reduce the interaction force between the molecules, and thereby reduce the melting point of the polyester and the copolyester.

[0007] Preferably, the molar ratio of the dibasic acid to the diol is 1:(1-2).

[0008] Preferably, the composite catalyst accounts for 0.02-0.05% of the total mass of the raw materials, the modifier accounts for 1-5% of the total mass of the esterification product, and the terminal hydroxyl silicone oil accounts for 5-8% of the total mass of the esterification product.

[0009] Preferably, the composite catalyst is at least two of a titanium-based catalyst, a silicon-based catalyst, a cobalt-based catalyst, an antimony-based catalyst, a tin-based catalyst, and a germanium-based catalyst.

[0010] By adopting the above technical solutions, titanium-based catalysts, silicon-based catalysts, cobalt-based catalysts, antimony-based catalysts, tin-based catalysts, and germanium-based catalysts can improve the efficiency of the polycondensation reaction by providing active centers, while controlling the molecular weight and molecular structure of the polyester.

[0011] Preferably, the modifier further comprises aspartic acid, and the mass ratio of ethylenediamine, aspartic acid and epoxy resin is (0.5-0.8):(0.8-1):1.

[0012] By adopting the above technical scheme, in the condensation reaction, the carboxyl group and amino group of aspartic acid can react with the hydroxyl group or carboxyl group in the polyester chain to form a new amide bond or ester bond, introducing polar groups. These polar groups can change the interaction force between molecules, change the crystallinity of polyester, and lower the melting point of polyester.

[0013] Preferably, the aspartic acid is modified with di-tert-butyl dicarbonate, and the modification method comprises the following specific steps: dissolving the aspartic acid under nitrogen, adding di-tert-butyl dicarbonate dropwise under ice bath conditions, then heating to 20-30° C. and stirring for reaction, removing the solvent by rotary evaporation, extracting and taking the organic layer, and drying to obtain the modified aspartic acid.

[0014] By adopting the above technical scheme, aspartic acid is modified by di-tert-butyl dicarbonate, so that tert-butoxy group can be introduced. The tert-butoxy group can react with aspartic acid and polyester polymer respectively to form new ester bonds, thereby improving the compatibility of aspartic acid with the polyester or copolyester matrix, promoting the uniform dispersion of aspartic acid in the polymer matrix, protecting the carboxyl group of aspartic acid from being destroyed in the subsequent high-temperature reaction, and improving the stability of the polyester and copolyester reactions.

[0015] Preferably, the dibasic acid is at least one of terephthalic acid, isophthalic acid, phthalic acid, succinic acid, glutaric acid, adipic acid and pimelic acid, and the diol is at least one of ethylene glycol, polyethylene glycol, neopentyl glycol, propylene glycol, butanediol, octanediol, dodecanediol and 1,4-cyclohexanedimethanol.

[0016] Preferably, the intrinsic viscosity of the polyester or copolyester is 0.5-1.0 dl / g, and the terminal carboxyl group is ≤25 mmol / kg.

[0017] Please have the following beneficial effects: 1. Since the present application uses ethylenediamine and epoxy resin as modifiers in the polycondensation reaction, and mixes with the esterification product to change the molecular structure of polyester and reduce the melting point of polyester and copolyester. The terminal hydroxyl silicone oil is introduced into the polyester molecular chain, and the structural regularity of polyester and copolyester is reduced by the introduction of silicon-containing components, thereby reducing the melting point of polyester and copolyester.

[0018] 2. In the present application, aspartic acid is used to react with the hydroxyl or carboxyl group in the polyester chain, and polar groups are introduced to change the crystallinity of the polyester and reduce the melting point of the polyester. At the same time, di-tert-butyl dicarbonate is used to modify aspartic acid to enhance the compatibility of aspartic acid with the polyester matrix, protect the carboxyl group of aspartic acid from being destroyed in the subsequent high-temperature reaction, and improve the stability of the polyester and copolyester reaction. DETAILED DESCRIPTION

[0019] The present application is further described in detail below in conjunction with embodiments.

[0020] All raw materials in the examples are commercially available. Example

[0021] Example 1 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: Using terephthalic acid and octanediol in a molar ratio of 1:1.5 as raw materials, the composite catalyst is a mixture of antimony trioxide and tetrabutyl titanate, the mass ratio of antimony trioxide to tetrabutyl titanate is 1:1, terephthalic acid, octanediol and the composite catalyst are mixed, the composite catalyst is 0.03% of the total mass of terephthalic acid and octanediol, heated to 80°C and stirred for 20 minutes, and then heated to 220°C under the protection of nitrogen for esterification reaction until water discharge is completed to obtain an esterified product.

[0022] S2: The esterified product is mixed with terminal hydroxyl silicone oil and a modifier, wherein the modifier accounts for 3% of the total mass of the esterified product. The modifier is a mixture of ethylenediamine and epoxy resin E44, and the mass ratio of ethylenediamine to epoxy resin is 1:1. The terminal hydroxyl silicone oil accounts for 7% of the total mass of the esterified product. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, which is extruded by nitrogen and granulated to obtain a polyester having a terminal carboxyl group ≤ 25 mmol / kg.

[0023] Example 2 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: Use terephthalic acid and octanediol in a molar ratio of 1:1 as raw materials, and a composite catalyst which is a mixture of antimony trioxide and tetrabutyl titanate, wherein the mass ratio of antimony trioxide to tetrabutyl titanate is 1:1, mix terephthalic acid, octanediol and the composite catalyst, wherein the composite catalyst accounts for 0.05% of the total mass of terephthalic acid and octanediol, heat to 80°C and stir for 20 minutes, then heat to 220°C under the protection of nitrogen to carry out esterification reaction until water discharge is completed, to obtain an esterified product.

[0024] S2: The esterified product is mixed with terminal hydroxyl silicone oil and a modifier, wherein the modifier accounts for 1% of the total mass of the esterified product. The modifier is a mixture of ethylenediamine and epoxy resin E44, and the mass ratio of ethylenediamine to epoxy resin is 1:1. The terminal hydroxyl silicone oil accounts for 8% of the total mass of the esterified product. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, which is extruded by nitrogen and granulated to obtain a polyester having a terminal carboxyl group ≤ 25 mmol / kg.

[0025] Example 3 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: Using terephthalic acid and octanediol in a molar ratio of 1:2 as raw materials, and a composite catalyst which is a mixture of antimony trioxide and tetrabutyl titanate, wherein the mass ratio of antimony trioxide to tetrabutyl titanate is 1:1, terephthalic acid, octanediol and the composite catalyst are mixed, wherein the composite catalyst accounts for 0.02% of the total mass of terephthalic acid and octanediol, and the mixture is heated to 80°C and stirred for 20 minutes, and then heated to 220°C under the protection of nitrogen to carry out esterification reaction until water discharge is completed, thereby obtaining an esterified product.

[0026] S2: The esterified product is mixed with terminal hydroxyl silicone oil and a modifier, wherein the modifier accounts for 5% of the total mass of the esterified product. The modifier is a mixture of ethylenediamine and epoxy resin E44, and the mass ratio of ethylenediamine to epoxy resin is 1:1. The terminal hydroxyl silicone oil accounts for 5% of the total mass of the esterified product. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, which is extruded by nitrogen and granulated to obtain a polyester having a terminal carboxyl group ≤ 25 mmol / kg.

[0027] Example 4 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: isophthalic acid and dodecyl glycol with a molar ratio of 1:1.5 are used as raw materials, and the composite catalyst is a mixture of stannous octoate and germanium dioxide, and the mass ratio of stannous trioctoate and germanium dioxide is 1:1. The isophthalic acid, dodecyl glycol and the composite catalyst are mixed, and the composite catalyst accounts for 0.03% of the total mass of the isophthalic acid and dodecyl glycol. After heating to 80°C and stirring for 20 minutes, the temperature is raised to 220°C under the protection of nitrogen to carry out esterification reaction until water discharge is completed to obtain an esterified product.

[0028] S2: The esterified product is mixed with terminal hydroxyl silicone oil and a modifier, wherein the modifier accounts for 3% of the total mass of the esterified product. The modifier is a mixture of ethylenediamine and epoxy resin E44, and the mass ratio of ethylenediamine to epoxy resin is 1:1. The terminal hydroxyl silicone oil accounts for 7% of the total mass of the esterified product. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, which is extruded by nitrogen and granulated to obtain a polyester having a terminal carboxyl group ≤ 25 mmol / kg.

[0029] Example 5 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: Using terephthalic acid and octanediol in a molar ratio of 1:1.5 as raw materials, the composite catalyst is a mixture of antimony trioxide and tetrabutyl titanate, the mass ratio of antimony trioxide to tetrabutyl titanate is 1:1, terephthalic acid, octanediol and the composite catalyst are mixed, the composite catalyst is 0.03% of the total mass of terephthalic acid and octanediol, heated to 80°C and stirred for 20 minutes, and then heated to 220°C under the protection of nitrogen for esterification reaction until water discharge is completed to obtain an esterified product.

[0030] S2: The esterified product is mixed with terminal hydroxyl silicone oil and a modifier, wherein the modifier accounts for 3% of the total mass of the esterified product. The modifier is a mixture of ethylenediamine, aspartic acid and epoxy resin E44, and the mass ratio of ethylenediamine, aspartic acid and epoxy resin is 0.6:0.9:1. The terminal hydroxyl silicone oil accounts for 7% of the total mass of the esterified product. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, which is extruded by nitrogen and granulated to obtain a polyester having a terminal carboxyl group ≤ 25 mmol / kg.

[0031] Example 6 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: Using terephthalic acid and octanediol in a molar ratio of 1:1.5 as raw materials, the composite catalyst is a mixture of antimony trioxide and tetrabutyl titanate, the mass ratio of antimony trioxide to tetrabutyl titanate is 1:1, terephthalic acid, octanediol and the composite catalyst are mixed, the composite catalyst is 0.03% of the total mass of terephthalic acid and octanediol, heated to 80°C and stirred for 20 minutes, and then heated to 220°C under the protection of nitrogen for esterification reaction until water discharge is completed to obtain an esterified product.

[0032] S2: The esterified product is mixed with terminal hydroxyl silicone oil and a modifier, wherein the modifier accounts for 3% of the total mass of the esterified product. The modifier is a mixture of ethylenediamine, aspartic acid and epoxy resin E44, and the mass ratio of ethylenediamine, aspartic acid and epoxy resin is 0.5:1:1. The terminal hydroxyl silicone oil accounts for 7% of the total mass of the esterified product. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, which is extruded by nitrogen and granulated to obtain a polyester having a terminal carboxyl group ≤ 25 mmol / kg.

[0033] Example 7 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: Using terephthalic acid and octanediol in a molar ratio of 1:1.5 as raw materials, the composite catalyst is a mixture of antimony trioxide and tetrabutyl titanate, the mass ratio of antimony trioxide to tetrabutyl titanate is 1:1, terephthalic acid, octanediol and the composite catalyst are mixed, the composite catalyst is 0.03% of the total mass of terephthalic acid and octanediol, heated to 80°C and stirred for 20 minutes, and then heated to 220°C under the protection of nitrogen for esterification reaction until water discharge is completed to obtain an esterified product.

[0034] S2: The esterified product is mixed with terminal hydroxyl silicone oil and a modifier, wherein the modifier accounts for 3% of the total mass of the esterified product. The modifier is a mixture of ethylenediamine, aspartic acid and epoxy resin E44, and the mass ratio of ethylenediamine, aspartic acid and epoxy resin is 0.8:0.8:1. The terminal hydroxyl silicone oil accounts for 7% of the total mass of the esterified product. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, which is extruded by nitrogen and granulated to obtain a polyester having a terminal carboxyl group ≤ 25 mmol / kg.

[0035] Example 8 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: Using terephthalic acid and octanediol in a molar ratio of 1:1.5 as raw materials, the composite catalyst is a mixture of antimony trioxide and tetrabutyl titanate, the mass ratio of antimony trioxide to tetrabutyl titanate is 1:1, terephthalic acid, octanediol and the composite catalyst are mixed, the composite catalyst is 0.03% of the total mass of terephthalic acid and octanediol, heated to 80°C and stirred for 20 minutes, and then heated to 220°C under the protection of nitrogen for esterification reaction until water discharge is completed to obtain an esterified product.

[0036] S2: Under nitrogen conditions, use sodium bicarbonate aqueous solution to dissolve aspartic acid, then add tetrahydrofuran solution, the mass ratio of tetrahydrofuran solution to sodium bicarbonate aqueous solution is 1:1, stir evenly under ice bath conditions, add di-tert-butyl dicarbonate dropwise, the mass ratio of di-tert-butyl dicarbonate to aspartic acid is 1:1, then raise the temperature to 25°C and stir to react for 12 hours, evaporate the solvent, extract the organic layer, and dry to obtain modified aspartic acid.

[0037] S3: The esterified product is mixed with terminal hydroxyl silicone oil and a modifier, wherein the modifier accounts for 3% of the total mass of the esterified product. The modifier is a mixture of ethylenediamine, aspartic acid and epoxy resin E44, and the mass ratio of ethylenediamine, modified aspartic acid and epoxy resin is 0.5:1:1. The terminal hydroxyl silicone oil accounts for 7% of the total mass of the esterified product. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, which is extruded by nitrogen and granulated to obtain a polyester having a terminal carboxyl group ≤ 25 mmol / kg.

[0038] Comparative Example Comparative Example 1 The present embodiment provides a method for preparing a low melting point polyester or copolyester by a synthetic method, comprising the following specific steps: S1: Using terephthalic acid and octanediol in a molar ratio of 1:1.5 as raw materials, the composite catalyst is a mixture of antimony trioxide and tetrabutyl titanate, the mass ratio of antimony trioxide to tetrabutyl titanate is 1:1, terephthalic acid, octanediol and the composite catalyst are mixed, the composite catalyst is 0.03% of the total mass of terephthalic acid and octanediol, heated to 80°C and stirred for 20 minutes, and then heated to 220°C under the protection of nitrogen for esterification reaction until water discharge is completed to obtain an esterified product.

[0039] S2: The esterified product is mixed with a modifier, wherein the modifier accounts for 3% of the total mass of the esterified product, and the modifier is a mixture of ethylenediamine and epoxy resin E44, and the mass ratio of ethylenediamine to epoxy resin is 1:1. A polycondensation reaction is carried out at 250°C for 10 minutes to obtain a melt, and the melt is pressed out by nitrogen and granulated to obtain polyester.

[0040] Performance testing The polyester prepared by the method for manufacturing low melting point polyester or copolyester according to the synthesis method provided in Examples 1-8 and Comparative Example 1 of the present application was subjected to the following performance tests, and the specific test results are shown in Table 1.

[0041] Detection Methods 1. Intrinsic viscosity With reference to the standard of GB / T10247-2008 "Viscosity Measurement Method", the SC-1632Z fully automatic intrinsic viscosity tester produced by Changsha Sichen Instrument Technology Co., Ltd. was used to test the intrinsic viscosity of the polyester prepared in this application.

[0042] 2. Melting point The melting point of the polyester prepared in the present application was tested using an X6 series microscopic melting point tester produced by Beijing Century Kexin Scientific Instrument Co., Ltd.

[0043] Table 1: Performance test results data table From the performance test results, it can be seen that the polyester prepared in the present application has a lower melting point and also maintains a certain intrinsic viscosity. By comparing Comparative Example 1 with Example 1, it can be seen that the polyester prepared in Comparative Example 1 does not use terminal hydroxyl silicone oil in the polyester raw material, and although the prepared polyester still has a lower melting point than conventional polyester, the melting point of the polyester is significantly increased compared with Example 1, further indicating that the introduction of the silicon-containing component can significantly reduce the melting point of the polyester.

[0044] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for producing a low melting point polyester or copolyester by synthesis, characterized in that: The method comprises the following specific steps: mixing dibasic acid and diol as raw materials with a composite catalyst and heating them, obtaining an esterified product after esterification reaction, mixing the esterified product with terminal hydroxyl silicone oil and a modifier for polycondensation reaction to obtain a melt, extruding the melt through an inert gas, and granulating to obtain a low melting point polyester or copolyester; the modifier comprises ethylenediamine and epoxy resin.

2. The method for producing low melting point polyester or copolyester by synthesis according to claim 1, characterized in that: The molar ratio of the dibasic acid to the diol is 1:(1-2).

3. The method for producing low melting point polyester or copolyester by synthesis according to claim 1, characterized in that: The composite catalyst accounts for 0.02-0.05% of the total mass of the raw materials, the modifier accounts for 1-5% of the total mass of the esterified product, and the terminal hydroxyl silicone oil accounts for 5-8% of the total mass of the esterified product.

4. The method for producing low melting point polyester or copolyester by synthesis according to claim 3, characterized in that: The composite catalyst is at least two of a titanium-based catalyst, a silicon-based catalyst, a cobalt-based catalyst, an antimony-based catalyst, a tin-based catalyst, and a germanium-based catalyst.

5. The method for producing low melting point polyester or copolyester by synthesis according to claim 3, characterized in that: The modifier also includes aspartic acid, and the mass ratio of ethylenediamine, aspartic acid and epoxy resin is (0.5-0.8): (0.8-1):

1.

6. The method for producing low melting point polyester or copolyester by synthesis according to claim 5, characterized in that: The aspartic acid is modified by di-tert-butyl dicarbonate, and the modification method comprises the following specific steps: dissolving the aspartic acid under nitrogen, adding di-tert-butyl dicarbonate dropwise under ice bath, heating to 20-30° C. and stirring for reaction, removing the solvent by rotary evaporation, extracting and taking the organic layer, and drying to obtain the modified aspartic acid.

7. The method for producing low melting point polyester or copolyester by synthesis according to claim 1, characterized in that: The dibasic acid is at least one of terephthalic acid, isophthalic acid, phthalic acid, succinic acid, glutaric acid, adipic acid and pimelic acid, and the diol is at least one of ethylene glycol, polyethylene glycol, neopentyl glycol, propylene glycol, butanediol, octanediol, dodecanediol and 1,4-cyclohexanedimethanol.

8. The method for producing low melting point polyester or copolyester by synthesis according to claim 1, characterized in that: The intrinsic viscosity of the polyester or copolyester is 0.5-1.0 dl / g, and the terminal carboxyl group is ≤25 mmol / kg.

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