CN116355187A - Polyester material and preparation method thereof - Google Patents

Abstract

The invention provides a polyester material and a preparation method thereof, wherein the polyester material is prepared by polymerizing aromatic dibasic acid or aromatic dibasic ester and aliphatic dihydric alcohol, and the aliphatic dihydric alcohol is 1, 4-cyclohexanediol, 2, 3-butanediol and C ₂ ～C ₆ Mixtures of linear alkylene glycols. The polyester material provided by the invention is a polyester material with high transparency, high glass transition temperature, high molecular weight and amorphous.

Description

A kind of polyester material and preparation method thereof

technical field

The invention relates to the technical field of polymer material synthesis, and furthermore, relates to a polyester material and a preparation method thereof.

Background technique

In recent years, as the fossil energy crisis has become increasingly severe, countries around the world have paid more and more attention to the development and utilization of biomass monomers. Following this, the types of bio-based materials are also developing rapidly. The application of various bio-based materials It is also becoming more widespread and is gradually replacing petroleum-based materials.

Bio-based material is a kind of green and environment-friendly material, some of its raw materials are renewable biomass raw materials, thus effectively reducing the use of non-renewable fossil energy and greatly relieving environmental pressure, which is in line with the trend of sustainable development today. Conducive to environmental protection.

Nowadays, there are more and more types of bio-based polymers, and bio-based polyester materials are one of them. Polyester materials have been widely used in many fields such as film, fiber, sheet, etc. due to their good mechanical properties, molding and processing properties, and easy degradation characteristics. They are the most important and the largest amount of synthetic materials in the world. one. With the continuous development of polyester materials, the types of polyester are also expanding to adapt to various application environments. Among the many polyester products, there are few products with high glass transition temperature and high light transmittance, which is one of the shortcomings of the polyester family.

2,3-butanediol is an isomer of 1,4-butanediol. It is a diol with two branched asymmetric methyl groups. The asymmetric methyl group can inhibit the rotation of the polyester molecular chain and destroy the molecular chain. The regular structure of the chain has a strong ability to inhibit the movement of molecular segments, which is conducive to increasing the glass transition temperature and inhibiting crystallization. Such as Chinese invention patent CN102093543A discloses a kind of preparation method of poly(2,3-butylene terephthalate) and copolyester thereof, selects dicarboxylic acid monomer or dimethyl ester monomer and 2,3-butanediol and Other reactive monomers make copolyesters. The reaction is divided into three steps: first, the aromatic dibasic acid or aromatic dibasic ester and linear diol are reacted to obtain prepolymer 1 through esterification or transesterification, and then the aromatic dibasic acid or aromatic dibasic ester Reaction with 2,3-butanediol to prepare prepolymer 2, and finally the two prepolymers were transesterified to obtain the product. The method adds linear diol and adopts the method of prepolymer reaction, which alleviates the problem of difficult polymerization of 2,3-butanediol to a certain extent. However, the steps of this polymerization method are cumbersome. Firstly, two kinds of prepolymers need to be synthesized separately, the continuity is poor, and the equilibrium molecular weight and glass transition temperature cannot be obtained only by linear diols.

Chinese invention patent CN103159907A discloses a high molecular weight polyester plastic based on 2,3-butanediol and its preparation method. Supplemented with one or more of aliphatic dibasic acids, aliphatic diols, and alicyclic diols to prepare 2,3-butanediol-based ester plastics, which are produced by esterification and transesterification in this patent The weight-average molecular weight of polyester is extremely low, which can only reach less than 5000. It is necessary to continue to react in a twin-screw extruder with isocyanate as a chain extender to obtain a product with a certain molecular weight. The steps are also cumbersome, and the temperature in the transesterification stage is as high as 240-280°C. It is well known that long-term high temperature in the polyester reaction will inevitably be accompanied by severe side reactions, and yellowing of the product is inevitable, which will affect the aesthetics and light transmittance of the product.

In summary, 2,3-butanediol is an excellent bio-based monomer for the preparation of polyester materials with high glass transition temperature and high transparency. The material is deficient in the field of high Tg transparent materials, but because the two hydroxyl groups of 2,3-butanediol are secondary hydroxyl groups, the reactivity is low, and the asymmetric methyl group increases the steric hindrance, making it difficult to polymerize , it is difficult to obtain high molecular weight polyester, which limits its development.

Contents of the invention

To solve the above problems, the present invention provides a polyester material and a preparation method thereof. The polyester material provided by the invention is an amorphous polyester material with high transparency, high glass transition temperature and high molecular weight, which further enriches and optimizes the types of polyester products.

First, one of the objects of the present invention is to provide a polyester material.

Specifically, the polyester material is obtained by polymerization of aromatic dibasic acids or aromatic dibasic esters, and aliphatic diols, and the general structural formula is:

in,

中的一种或组合；和/或，R ₁ is one or a combination of aromatic rings, preferably

one or a combination of; and/or,

R ₂ is one or a combination of C ₂ -C ₆ linear linear alkanediols, preferably one or a combination of C ₄ -C ₆ linear linear alkanediols;

x is 0.30-0.80 mole fraction, preferably 0.35-0.65 mole fraction; y is 0.08-0.40 mole fraction, preferably 0.15-0.30 mole fraction; z is 0-0.40 mole fraction, preferably 0.10-0.35 mole fraction.

The second object of the present invention is to provide the preparation method of the polyester material according to one of the objects.

Include the following steps:

After fully mixing aromatic dibasic acid or aromatic dibasic ester, aliphatic dibasic alcohol, catalyst, and antioxidant, first perform transesterification to obtain a prepolymer, and then perform polycondensation to obtain the polyester material.

Specifically, the preparation method comprises the following steps:

S1, transesterification reaction

Add aromatic dibasic acid or aromatic dibasic ester, aliphatic dibasic alcohol, catalyst, and antioxidant into the reaction kettle and mix thoroughly. Under the condition of protective gas, the temperature of the reaction system is slowly raised to 180~220℃ within 2~4 hours. °C, preferably 200-220 °C, and kept at this temperature for 2-6 hours. The slow heating process can also effectively prevent a large amount of diol monomers from evaporating and discharging under high temperature conditions.

It is worth mentioning that on the basis of the traditional condensing device, this device is equipped with a Webster fractionation column, whose function is to control the temperature of the Webster fractionation column, so that the diol monomers can return to the reactor to continue to participate in the reaction. The small molecules produced by the reaction are excluded from the reactor, so that the reaction temperature can be raised above the boiling point of the monomer, and the loss of the monomer can be effectively reduced.

Further, the molar ratio of the amount of aromatic dibasic acid or aromatic dibasic ester to aliphatic dihydric alcohol is 1:1.2-1:2, preferably 1:1.4-1:1.8.

Further, the amount of the catalyst used is 0.05-1.0% of the total mass of the aromatic dibasic acid or aromatic dibasic ester and the aliphatic dihydric alcohol; preferably 0.2-0.6%.

Further, the amount of the antioxidant is 0.01-0.2% of the total mass of the aromatic dibasic acid or aromatic dibasic ester and the aliphatic dihydric alcohol; more preferably 0.01-0.1%.

Preferably, in a preferred embodiment of the present invention, the aromatic dibasic acid or aromatic dibasic ester is one of terephthalic acid, isophthalic acid, phthalic acid, and dimethyl terephthalate or a combination.

Preferably, in a preferred embodiment of the present invention, the aliphatic diol is a mixture of 1,4-cyclohexanediol, 2,3-butanediol, and C ₂ -C ₆ linear linear alkanediol, wherein , in aliphatic diols, 1,4-cyclohexanediol accounts for 8 to 40% of the total molar ratio of aliphatic diols, and 2,3-butanediol accounts for 30% of the total molar ratio of aliphatic diols ~80%, linear alkanediol accounts for 0~40% of the total molar ratio of aliphatic dihydric alcohols.

Preferably, in a preferred embodiment of the present invention, the C ₂ -C ₆ linear linear alkanediol is ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, One or a combination of 1,6-hexanediol.

Preferably, in a preferred embodiment of the present invention, the catalyst is selenium dioxide, antimony trioxide, antimony ethylene glycol, p-toluenesulfonic acid, acetate, alkylaluminum with 1 to 12 carbon atoms, organic One or a combination of tin compounds and titanates; preferably stannous octoate.

Preferably, in a preferred embodiment of the present invention, the antioxidant is one or a combination of phosphoric acid, phosphorous acid, phosphoric acid ester, phosphorous acid ester, and phenyl phosphate.

S2, polycondensation reaction

First raise the temperature of the reaction system to 200-240°C, preferably 210-230°C, and pre-condense at 3-10kPa for 1-4h; then vacuumize the reaction system to below 500Pa, and finally polycondense for 2-12h to complete the reaction . Among them, the reaction temperature of polycondensation can not only ensure that the reaction system has a considerable reaction speed, but also prevent a large number of thermal degradation reactions in the system.

Compared with the prior art, the beneficial effects of the present invention are:

1. The present invention uses bio-based 2,3-butanediol and bio-based linear diol as raw materials to prepare polyester materials, which responds to the national double-carbon strategy and alleviates the impending depletion of petrochemical energy.

2. The present invention optimizes the reaction process, adds a Webster fractionation column and improves the reaction temperature, effectively improves the reaction efficiency, suppresses the yellowing phenomenon, and significantly improves the molecular weight and aesthetics of the material.

3. The present invention introduces 1,4-cyclohexanediol and straight-chain diol into the polyester material at the same time, and successfully prepares the polyester material with 2,3-butanediol, solving the problem of 2,3-butanediol The problem of difficult alcohol polymerization balances the relationship between molecular weight and glass transition temperature, obtains polyester materials with both high molecular weight and high Tg, and enriches and optimizes the types of polyester materials.

4. The present invention prepares polyester materials by substituting 1,4-cyclohexanediol for part of 2,3-butanediol, utilizing the higher reactivity of 1,4-cyclohexanediol than 2,3-butanediol, And further improved the glass transition temperature and appearance.

5. The polyester material prepared by the present invention through aromatic dibasic acid or dibasic ester, 2,3-butanediol, 1,4-cyclohexanediol and linear diol has a high glass transition temperature, and the use temperature is The upper limit is high, which is enough to meet most of the needs of medium and high temperature use in daily life, and has a wide application prospect.

6. The polyester material obtained in the present invention is an amorphous material, has good light transmittance and low haze, has no obvious yellowing phenomenon, and has good aesthetics. This polyester material can be applied to transparent packaging and other transparency and Use in areas with high temperature requirements.

Description of drawings

Fig. 1 is the nuclear magnetic spectrogram of the polyester material that preferred embodiment 1 of the present invention prepares;

Detailed ways

Below in conjunction with specific accompanying drawing and embodiment the present invention is carried out concrete description, it is necessary to point out here that following embodiment is only used for further explanation of the present invention, can not be interpreted as the restriction to protection scope of the present invention, those skilled in the art according to the present invention Summary of the invention Some non-essential improvements and adjustments made to the present invention still belong to the protection scope of the present invention.

The raw materials and reagents used in the following examples are from commercially available products.

Example 1

Add dimethyl terephthalate, 2,3-butanediol, 1,4-cyclohexanediol, and ethylene glycol into the reaction kettle, wherein the molar ratio of dimethyl terephthalate to diol is 1 :1.2, the molar ratio of the three diols is 0.35:0.3:0.35. Stannous octoate (0.3% of the total mass) and triphenyl phosphite (0.03% of the total mass) were added into a reaction kettle with a reflux condenser, and fully mixed under a nitrogen atmosphere.

Slowly raise the temperature of the system to 200°C within 2 hours, maintain normal pressure, react at 200°C for 4 hours, and discharge methanol; then raise the temperature of the system to 220°C, reduce the pressure to 5kPa, continue prepolymerization for 2 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.35, y=0.30, z=0.35.

Figure 1 is the NMR spectrum of the polyester material prepared in this example. It can be seen from the figure that 5.39ppm (d, d`) corresponds to -O-CH (CH <sub>3</sub> )- The absorption peak at 1.44ppm (c,i,i`) corresponds to the -CH ₃ characteristic absorption peaks of different chiral 2,3-BDO structural units in the molecular chain and at the end of the molecular chain, 3.92ppm and 4.03ppm ( h, h`) corresponds to the absorption peak of HO-CH(CH <sub>3</sub> )- in 2,3-BDO at the chain end, and 4.52ppm and 4.57ppm (g,g`) correspond to the 2,3-BDO at the chain end The characteristic absorption peak of HO-CH(CH ₃ )-CH(CH ₃ )- in is, 8.05ppm (a) corresponds to the characteristic absorption peak on the benzene ring (CH), and 4.69ppm (b) corresponds to the characteristic absorption peak in EG The characteristic absorption peak of -O-CH ₂ -CH ₂ -O-, at 5.18ppm (e), corresponds to the absorption peak of -O-CH- in 1,4-CHD monomer, at 2.17ppm～1.80ppm (f) It corresponds to the absorption peak of -CH ₂ - on the six-membered ring.

Example 2

Add dimethyl terephthalate, 2,3-butanediol, 1,4-cyclohexanediol, and ethylene glycol into the reaction kettle, wherein the molar ratio of dimethyl terephthalate to diol is 1 :1.5, the molar ratio of the three diols is 0.65:0.08:0.27. Add stannous octoate (0.05% of the total mass) and phosphorous acid (0.1% of the total mass) into a reaction kettle with a reflux condenser, and mix thoroughly under a nitrogen atmosphere.

Slowly raise the temperature of the system to 180°C within 2 hours, maintain normal pressure, react at 180°C for 3 hours, and discharge methanol; then raise the temperature of the system to 200°C, reduce the pressure to 5kPa, continue prepolymerization for 2 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.65, y=0.08, z=0.27.

Example 3

Add terephthalic acid, 2,3-butanediol, 1,4-cyclohexanediol, and 1,4-butanediol into the reaction kettle, wherein the molar ratio of dimethyl terephthalate to diol is 1:1.5, the molar ratio of the three diols is 0.5:0.2:0.3. Tetrabutyl titanate (1.0% of the total mass) and triethyl phosphate (0.2% of the total mass) were added into a reaction kettle with a reflux condenser, and fully mixed under a nitrogen atmosphere.

Slowly raise the temperature of the system to 200°C within 2 hours, maintain normal pressure, react at 200°C for 4 hours, and discharge methanol; then raise the temperature of the system to 220°C, drop the pressure to 5kPa, continue prepolymerization for 3 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.5, y=0.2, z=0.3.

Example 4

Add phthalic acid, dimethyl terephthalate, 2,3-butanediol, 1,4-cyclohexanediol, 1,6-hexanediol into the reaction kettle, in which phthalic acid, terephthalate The molar ratio of dimethyl phthalate to diol is 1:1.5 (the molar ratio of phthalic acid to dimethyl terephthalate is 1:2), and the molar ratio of the three diols is 0.65:0.3 :0.05. Antimony trioxide (1.0% of the total mass) and trimethyl phosphite (0.1% of the total mass) were added into a reaction kettle with a reflux condenser, and fully mixed under a nitrogen atmosphere.

Slowly raise the temperature of the system to 220°C within 2 hours, maintain normal pressure, react at 220°C for 3 hours, and discharge methanol; then raise the temperature of the system to 240°C, reduce the pressure to 5kPa, continue prepolymerization for 4 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material structure is as follows, wherein, x=0.65, y=0.3, z=0.05, R is

Example 5

Add isophthalic acid, 2,3-butanediol, 1,4-cyclohexanediol, and 1,5-pentanediol into the reaction kettle, and the molar ratio of isophthalic acid to diol is 1:1.7 , the molar ratio of the three diols is 0.55:0.3:0.15. Antimony ethylene glycol (0.6% of the total mass) and triphenyl phosphite (0.2% of the total mass) were added into a reaction kettle with a reflux condenser, and mixed thoroughly under a nitrogen atmosphere.

Slowly raise the temperature of the system to 220°C within 2 hours, maintain normal pressure, react at 220°C for 4 hours, and discharge methanol; then raise the temperature of the system to 220°C, drop the pressure to 5kPa, continue prepolymerization for 4 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.55, y=0.3, z=0.15.

Example 6

Add terephthalic acid, dimethyl terephthalate, 2,3-butanediol, 1,4-cyclohexanediol, and 1,4-butanediol into the reaction kettle, of which phthalic acid, terephthalate The molar ratio of dimethyl diformate to diol is 1:1.5, (the molar ratio of terephthalic acid to dimethyl terephthalate is 1:1) and the molar ratio of the three diols is 0.35:0.3:0.35 . Stannous octoate (0.3% of the total mass) and triphenyl phosphite (0.1% of the total mass) were added into a reaction kettle with a reflux condenser, and fully mixed under a nitrogen atmosphere.

Slowly raise the temperature of the system to 200°C within 2 hours, maintain normal pressure, react at 200°C for 3 hours, and discharge methanol; then raise the temperature of the system to 220°C, drop the pressure to 5kPa, continue prepolymerization for 2 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.35, y=0.3, z=0.35.

Example 7

Add terephthalic acid, 2,3-butanediol, 1,4-cyclohexanediol, and 1,4-butanediol into the reaction kettle, wherein the molar ratio of terephthalic acid to diol is 1:1.7 , the molar ratio of the three diols is 0.42:0.28:0.3. Tetraethyl titanate (0.5% of the total mass) and trimethyl phosphite (0.1% of the total mass) were added into a reaction kettle with a reflux condenser, and fully mixed under a nitrogen atmosphere.

Slowly raise the temperature of the system to 210°C within 2 hours, maintain normal pressure, react at 210°C for 3 hours, and discharge methanol; then raise the temperature of the system to 220°C, drop the pressure to 5kPa, continue prepolymerization for 2 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.42, y=0.28, z=0.3.

Example 8

Add dimethyl terephthalate, 2,3-butanediol, 1,4-cyclohexanediol, and ethylene glycol into the reaction kettle, wherein the molar ratio of dimethyl terephthalate to diol is 1 :2, the molar ratio of the three diols is 0.42:0.28:0.3. Selenium dioxide (0.05% of the total mass) and trimethyl phosphite (0.1% of the total mass) were added into a reaction kettle with a reflux condenser, and mixed thoroughly under a nitrogen atmosphere.

Slowly raise the temperature of the system to 200°C within 2 hours, maintain normal pressure, react at 200°C for 2 hours, and discharge methanol; then raise the temperature of the system to 220°C, reduce the pressure to 5kPa, continue prepolymerization for 2 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.42, y=0.28, z=0.3.

Example 9

Add dimethyl terephthalate, 2,3-butanediol, and 1,4-cyclohexanediol into the reaction kettle, wherein the molar ratio of dimethyl terephthalate to diol is 1:1.5, two The molar ratio of the diols is 0.7:0.3. Stannous octoate (0.3% of the total mass) and triphenyl phosphite (0.03% of the total mass) were added into a reaction kettle with a reflux condenser, and fully mixed under a nitrogen atmosphere.

Slowly raise the temperature of the system to 200°C within 2 hours, maintain normal pressure, react at 200°C for 3 hours, and discharge methanol; then raise the temperature of the system to 220°C, reduce the pressure to 5kPa, continue prepolymerization for 4 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.7, y=0.3.

Comparative example 1

Add dimethyl terephthalate, 2,3-butanediol, and ethylene glycol into the reactor, wherein the molar ratio of dimethyl terephthalate to diol is 1:1.5, and the molar ratio of the two diols is 0.5:0.5. Stannous octoate (0.3% of the total mass) and triphenyl phosphite (0.03% of the total mass) were added into a reaction kettle with a reflux condenser, and fully mixed under a nitrogen atmosphere.

Slowly raise the temperature of the system to 200°C within 2 hours, maintain normal pressure, react at 200°C for 2 hours, and discharge methanol; then raise the temperature of the system to 220°C, reduce the pressure to 5kPa, continue prepolymerization for 2 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.5, z=0.5.

Comparative example 2

Add dimethyl terephthalate, 1,4-cyclohexanediol, and ethylene glycol into the reactor, wherein the molar ratio of dimethyl phthalate to diol is 1:1.5, and the molar ratio of the two diols is 0.5:0.5. Stannous octoate (0.3% of the total mass) and triphenyl phosphite (0.03% of the total mass) were added into a reaction kettle with a reflux condenser, and fully mixed under a nitrogen atmosphere.

Slowly raise the temperature of the system to 200°C within 2 hours, maintain normal pressure, react at 200°C for 2 hours, and discharge methanol; then raise the temperature of the system to 220°C, reduce the pressure to 5kPa, continue prepolymerization for 2 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material structure is as follows, wherein, y=0.5, z=0.5

Comparative example 3

Add dimethyl terephthalate, 2,3-butanediol, 1,4-cyclohexanediol, and ethylene glycol into the reactor, wherein the molar ratio of dimethyl terephthalate to glycol is 1: 1.5, the molar ratio of the three diols is 0.2:0.2:0.6. Add stannous octoate (0.3% of the total mass) and triphenyl phosphite (0.02% of the total mass) into a reaction kettle with a reflux condenser, and mix thoroughly under a nitrogen atmosphere.

Slowly raise the temperature of the system to 200°C within 2 hours, maintain normal pressure, react at 200°C for 4 hours, and discharge methanol; then raise the temperature of the system to 220°C, reduce the pressure to 5kPa, continue prepolymerization for 2 hours, and finally continue to vacuum the system. Continue polycondensation until the end of the reaction, the obtained polyester material has the following structure, wherein, x=0.2, y=0.2, z=0.6.

Comparative example 4

This comparative example follows the preparation method and proportioning provided by Chinese patent CN 103159907A. Add 46.6g of dimethyl terephthalate, 32.4g of 2,3-butanediol, 41.8g of 1,4-cyclohexanediol, and 0.12g of tetra-n-butyl titanate into a three-necked flask, and react under nitrogen under conditions. Heat to 220°C. After the reactants form a homogeneous system, control the reaction temperature to 220°C and react for 3 hours. During this process, water is distilled from the reaction mixture as a by-product until the amount of the distillate reaches the theoretically calculated amount. 92%. 0.12 g of antimony trioxide and 0.10 g of trimethyl phosphate were respectively added to the reaction mixture as a polycondensation reaction catalyst (ie, the second catalyst) and a heat stabilizer. The polymerization reaction is carried out at a temperature of 250° C., vacuumed to less than 500 Pa, stirred for 3 hours, and the reaction is stopped. The structure of the obtained polyester material is as follows, wherein, x=0.5, y=0.5.

Table 1 is used to illustrate the performance of the polyester material that embodiment 1～9, comparative example 1～4 make, specifically as follows:

Mw(g/mol) Tg(°C) Tm(°C) Transmittance(%) Example 1 20600 113 n.d. 91 Example 2 22200 118 n.d. 91 Example 3 23600 104 n.d. 89 Example 4 16600 97 n.d. 89 Example 5 26600 95 n.d. 90 Example 6 21700 112 n.d. 91 Example 7 19600 109 n.d. 91 Example 8 17100 110 n.d. 90 Example 9 19800 121 n.d. 89 Comparative example 1 21500 100 n.d. 81 Comparative example 2 18400 77 218 n.d. Comparative example 3 26000 90 232 n.d. Comparative example 4 3300 52 n.d. 47

From the data in Table 1, it can be seen that the glass transition temperatures of a series of polyester materials prepared by the present invention are all above 95°C, which is at a relatively high level, and the light transmittance is maintained above 89%, which is also very excellent. Among them, the glass transition temperature of the polyester material prepared in Example 9 can reach 121° C., and the light transmittance can reach 91%, which is higher than most polyester materials. From Comparative Example 1, it can be seen that without adding 1,4-cyclohexanediol, the light transmittance of the polyester material is greatly reduced, which is due to the more stable six-membered ring structure. Side reactions are not easy to occur, making the system more uniform, and its strong rigid structure further destroys the crystallization ability of polyester; from Comparative Example 2, it can be seen that without adding 2,3-butanediol, the polyester material appeared Crystallization phenomenon, which becomes opaque, and the glass transition temperature has also dropped significantly, which shows that the 2,3-butanediol unit has a strong ability to destroy crystallization and inhibit the movement of chain segments, which is crucial for the preparation of high Tg transparent materials Important; as can be seen from Comparative Example 3, when the amount of linear diol is too much, crystallization will occur in the polyester material. Therefore, when preparing polyester materials, it is also necessary to strictly control the amount of linear diol; it can be seen from Comparative Example 4 , This application provides a preparation method of polyester material with better molecular weight, Tg and light transmittance.

Claims (10)

1. The polyester material is characterized by comprising an aromatic dibasic acid or aromatic dibasic ester and aliphatic dihydric alcohol, wherein the polyester material is obtained by polymerization of the aromatic dibasic acid or the aromatic dibasic ester and the aliphatic dihydric alcohol and has a structural general formula:

wherein,,

R ₁ is one or a combination of aromatic rings; and/or the number of the groups of groups,

R ₂ is C ₂ ～C ₆ One or a combination of linear straight chain alkane diols;

x is 0.30 to 0.80 mole fraction;

y is 0.08 to 0.40 mole fraction;

z is 0 to 0.40 mole fraction.

2. The polyester material according to claim 1, wherein in the structural formula,

R ₁ is that

One or a combination of the above; and/or the number of the groups of groups,

R ₂ is C ₄ ～C ₆ One or a combination of linear straight chain alkane diols;

x is 0.35 to 0.65 mole fraction;

y is 0.15 to 0.30 mole fraction;

z is 0.10 to 0.35 mole fraction.

3. A process for the preparation of a polyester material as claimed in claim 1 or 2, comprising the steps of:

fully mixing aromatic dibasic acid or aromatic dibasic ester, aliphatic dibasic alcohol, catalyst and antioxidant, performing transesterification reaction to obtain prepolymer, and performing polycondensation reaction to obtain the polyester material.

4. A process for preparing a polyester material as claimed in claim 3, wherein,

the aromatic dibasic acid or the aromatic dibasic ester is one or the combination of terephthalic acid, isophthalic acid, phthalic acid and dimethyl terephthalate; and/or the number of the groups of groups,

the aliphatic dihydric alcohol is 1, 4-cyclohexanediol, 2, 3-butanediol, C ₂ ～C ₆ Mixtures of linear alkylene glycols.

5. The method for producing a polyester material according to claim 4, wherein,

in the aliphatic diol, the 1, 4-cyclohexanediol accounts for 8-40% of the total mole ratio of the aliphatic diol, the 2, 3-butanediol accounts for 30-80% of the total mole ratio of the aliphatic diol, and the linear chain alkanediol accounts for 0-40% of the total mole ratio of the aliphatic diol.

6. The method for producing a polyester material according to claim 4, wherein,

the C is ₂ ～C ₆ The linear straight chain alkylene glycol is one or a combination of ethylene glycol, 1, 3-propylene glycol, 1, 4-butanediol, 1, 5-pentanediol and 1, 6-hexanediol.

7. A process for preparing a polyester material as claimed in claim 3, wherein,

the molar ratio of the aromatic dibasic acid or aromatic dibasic ester to the aliphatic dihydric alcohol is 1:1.2-1:2, preferably 1:1.4-1:1.8.

8. A process for preparing a polyester material as claimed in claim 3, wherein,

the catalyst is one or a combination of selenium dioxide, antimonous oxide, ethylene glycol antimon, p-toluenesulfonic acid, acetate, alkyl aluminum with 1-12 carbon atoms, organic tin compounds and titanate; stannous octoate is preferred;

the dosage of the catalyst is 0.05-1.0% of the total mass of the aromatic dibasic acid or the aromatic dibasic ester and the aliphatic dihydric alcohol; preferably 0.2 to 0.6%.

9. A process for preparing a polyester material as claimed in claim 3, wherein,

the antioxidant is one or a combination of phosphoric acid, phosphorous acid, phosphate ester, phosphite ester and phenyl phosphate;

the dosage of the antioxidant is 0.01-0.2% of the total mass of the aromatic dibasic acid or the aromatic dibasic ester and the aliphatic dihydric alcohol; preferably 0.01 to 0.1%.

10. A process for preparing a polyester material as claimed in claim 3, wherein,

the transesterification is carried out under the condition of protective gas, and the transesterification system needs to be heated to 180-220 ℃ within 2-4 h, preferably 200-220 ℃, and kept at the temperature for 2-6 h;

when the polycondensation reaction is carried out, the reaction system is firstly heated to 200-240 ℃, preferably 210-230 ℃, and pre-polycondensed for 1-4 hours under 3-10 kPa; then the reaction system is vacuumized to below 500Pa and polycondensed for 2-12 h.

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