阅读说明：本技术 二元醇改性的对苯二甲酸乙二醇共聚酯的制造方法及其应用 (Preparation method and application of glycol modified ethylene terephthalate copolyester ) 是由 黄昱豪 许瑞熙 于 2021-04-29 设计创作，主要内容包括：本发明公开了一种二元醇改性的对苯二甲酸乙二醇共聚酯的制造方法及其,制造方法包括下述步骤。提供反应混合物。反应混合物包括对苯二甲酸、乙二醇、1,4-环己烷二甲醇及一水性钛类触媒。使反应混合物进行酯化反应与缩聚合反应以得到二元醇改性的对苯二甲酸乙二醇共聚酯。(The invention discloses a method for preparing glycol modified ethylene terephthalate copolyester and a preparation method thereof. A reaction mixture is provided. The reaction mixture comprises terephthalic acid, ethylene glycol, 1,4-cyclohexanedimethanol and an aqueous titanium catalyst. And carrying out esterification reaction and polycondensation reaction on the reaction mixture to obtain the glycol modified ethylene terephthalate copolyester.)

1. A method for making glycol-modified ethylene terephthalate copolyester, comprising:

providing a reaction mixture, wherein the reaction mixture comprises terephthalic acid, ethylene glycol, 1,4-cyclohexanedimethanol and an aqueous titanium catalyst; and

and carrying out esterification reaction and polycondensation reaction on the reaction mixture to obtain the glycol modified ethylene terephthalate copolyester.

2. The process for producing the glycol-modified ethylene terephthalate copolyester according to claim 1, wherein the polycondensation reaction has a reaction temperature higher than the esterification reaction and a reaction pressure lower than the esterification reaction.

3. The method of claim 1, wherein the aqueous titanium catalyst comprises an organic acid chelated titanium complex, an organic base chelated titanium complex, or a combination thereof.

4. The method of claim 3, wherein the organic acid chelated titanium complex is selected from the group consisting of citric acid chelated titanium complex, lactic acid chelated titanium complex, ammonium lactate chelated titanium complex, and any combination thereof; the organic base chelated titanium coordination compound comprises a triethanolamine chelated titanium complex.

5. The method according to claim 1, wherein the reaction mixture further comprises a metal catalyst selected from the group consisting of zinc acetate, manganese acetate, calcium acetate, magnesium acetate, cobalt acetate, and any combination thereof.

6. The process for making the glycol-modified ethylene terephthalate copolyester of claim 5, wherein the moles of the ethylene glycol in the reaction mixture are greater than the moles of the 1, 4-cyclohexanedimethanol.

7. The method of claim 1, further comprising adding a phosphorus stabilizer to the reaction mixture after the esterification reaction.

8. The process for producing the glycol-modified ethylene terephthalate copolyester according to claim 1, wherein the polycondensation is carried out simultaneously with or after the esterification.

9. The process for producing the glycol-modified ethylene terephthalate copolyester according to claim 1, wherein the glycol-modified ethylene terephthalate copolyester comprises 1,4-cyclohexanedimethanol units formed from the 1,4-cyclohexanedimethanol and ethylene glycol units formed from the ethylene glycol, and the percentage of the moles of the 1,4-cyclohexanedimethanol units to the total moles of the 1,4-cyclohexanedimethanol units and the ethylene glycol units in the glycol-modified ethylene terephthalate copolyester is at least 10 mol%.

10. A molded article made of the glycol-modified ethylene terephthalate copolyester obtained by the production method according to any one of claims 1to 9.

Technical Field

The disclosure relates to a method for preparing glycol modified ethylene terephthalate copolyester and application thereof.

Background

The polyester terephthalate material, taking polyethylene terephthalate as an example, is a milky or light yellow polymer with high crystallinity and smooth and glossy surface, and has the advantages of wide application temperature range, excellent physical and mechanical properties, high electrical insulation, high creep resistance, high fatigue resistance, high friction resistance and good dimensional stability; and the cost is low, so that the method is widely applied to industries such as textiles, plastics, films, PET bottles and the like.

However, the conventional polyethylene terephthalate has insufficient toughness due to high crystallinity, and thus limits its application range. In order to increase its added value, the prior art uses diol (diol), such as 1,4-Cyclohexanedimethanol (CHDM) or Ethylene Glycol (EG), to modify polyethylene terephthalate or poly-1, 4-cyclohexanedimethanol terephthalate to form a functional copolyester terephthalate material, such as polyethylene terephthalate1,4-cyclohexanedimethanol modified copolyester (polyethylene terephthalate1, 4-cyclohexanedimethylene modified, PETG) or polyethylene terephthalate1,4-cyclohexanedimethanol modified copolyester (poly1, 4-cyclohexanedimethylene modified, pcg) to make it have better optical properties, high transparency, impact resistance, heat resistance, gas resistance, chemical resistance, gamma resistance, printing resistance, and electrostatic resistance, and no tg, can be widely applied to industries such as medical science, optics, electronic products, food/cosmetic packaging, signboards/storage racks, furniture, building materials and the like.

The method for producing a terephthalic acid copolyester material with excellent properties can be classified into an esterification method using terephthalic acid as a starting material and an ester exchange method using dimethyl terephthalate (DMT) as a starting material, depending on the starting material. Since the esterification process using terephthalic acid as a starting material has water as a by-product rather than methanol, the water phase is easier to remove and safer than methanol. Therefore, the esterification method using terephthalic acid as a starting material is preferred in the process.

However, the water produced as a by-product in the esterification reaction of terephthalic acid hydrolyzes the non-aqueous catalyst commonly used in the prior art to lose catalytic activity and form insoluble precipitates, which in turn reduces the transparency of the final product. In addition, under the high-temperature reaction condition, ethylene glycol can be dehydrated to generate a by-product diethylene glycol (DEG), and diethylene glycol participates in polymerization to enable a molecular chain of the 1,4-cyclohexanedimethanol modified copolyester (PETG) of polyethylene terephthalate to have a diethylene glycol unit, so that the molecular chain of the 1,4-cyclohexanedimethanol modified copolyester (PETG) of the polyethylene terephthalate becomes soft, the Glass Transition temperature (Tg) of the PETG is reduced, and the processing problems of insufficient mechanical properties and thermal stability of the polyester are caused. When the nonaqueous catalyst is hydrolyzed in the esterification reaction, resulting in a decrease in activity, the reaction time will be lengthened, resulting in an increase in the diethylene glycol unit in the polyester molecule, which worsens the above-mentioned processing problems. If the amount of the non-aqueous catalyst is supplemented, the hue of the final product will be deteriorated.

Therefore, there is a need to provide an advanced method for manufacturing terephthalic acid copolyester and its application to solve the problems faced by the prior art.

Disclosure of Invention

One embodiment of the present disclosure discloses a method for manufacturing glycol-modified ethylene terephthalate copolyester, comprising the following steps: a reaction mixture is provided. The reaction mixture comprises terephthalic acid, ethylene glycol, 1,4-cyclohexanedimethanol and an aqueous titanium catalyst. And carrying out esterification reaction and polycondensation reaction on the reaction mixture to obtain the glycol modified ethylene terephthalate copolyester.

One embodiment of the present disclosure discloses a product made of the above glycol-modified ethylene terephthalate copolyester.

Drawings

FIG. 1 is a graph showing the relationship between the content of titanium in the dibasic acid of the titanium-based catalyst and the number average molecular weight of the polyester produced in examples 1to 3 and comparative examples 1to 3.

FIG. 2 is a graph showing the relationship between the content of titanium in the dibasic acid of the titanium-based catalyst in examples 1to 3 and comparative examples 1to 3 and the mole fraction of diethylene glycol unit to diol unit of the polyester produced.

FIG. 3 is a graph showing the relationship between the content of the dibasic acid in titanium of the titanium catalyst and the hue value of the polyester obtained in examples 1to 3 and comparative examples 1to 3.

Detailed Description

The specification provides a preparation method and application of glycol modified ethylene terephthalate copolyester, and the glycol modified ethylene terephthalate copolyester has good mechanical property, good color phase, high transparency and high thermal stability.

A process for making a glycol-modified ethylene terephthalate copolyester comprising the steps of: providing a reaction mixture, and carrying out esterification reaction and polycondensation reaction on the reaction mixture to obtain the glycol modified ethylene terephthalate copolyester. The reaction mixture comprises terephthalic acid, ethylene glycol, 1,4-cyclohexanedimethanol and an aqueous titanium catalyst.

In one embodiment, the amount of ethylene glycol in the reaction mixture may be greater than 1,4-cyclohexanedimethanol, for example, the molar ratio of ethylene glycol: the mole number of the 1,4-cyclohexanedimethanol may be 2-10: 1, or 5-10: 1. In another example, the reaction mixture contains ethylene glycol in an amount similar to 1,4-cyclohexanedimethanol, e.g., moles of ethylene glycol: the mole number of the 1,4-cyclohexanedimethanol may be 1: 2to 2: 1. In another embodiment, the amount of ethylene glycol in the reaction mixture may be less than 1,4-cyclohexanedimethanol, for example, the molar ratio of ethylene glycol: the mole number of the 1,4-cyclohexanedimethanol may be 1: 2to 10, or 1: 5to 10.

Molar number of terephthalic acid: the mole number of the ethylene glycol can be 1: 1-5, or 1: 2-4.

The aqueous titanium catalyst comprises an organic acid chelated titanium complex, an organic base chelated titanium complex, or a combination thereof. Organic acid chelated titanium complexes (titanium (iv) carboxylate complexes) include, for example, citric acid chelated titanium complexes (titanium (iv) citrate complexes), lactic acid chelated titanium complexes (titanium (iv) lactic acid chelate complexes), ammonium lactate chelated titanium complexes (titanium (iv) lactic acid ammonium salts complexes), or combinations thereof. Examples of the organic base chelate titanium complex include triethanolamine chelate titanium complexes (titanium (iv) and the like). The aqueous titanium catalyst of the reaction mixture has a titanium content of greater than 60ppm, for example from 60ppm to 1000ppm, or from 60ppm to 500ppm, or from 60ppm to 100ppm, based on the diacid content.

In some embodiments, the aqueous titanium-based catalyst of the reaction mixture has a titanium content of less than 30ppm, such as from 1ppm to 30ppm, or from 5ppm to 25ppm, or from 10ppm to 25ppm, based on the diacid (including terephthalic acid).

Because the citric acid chelated titanium complex adopts triprotic citric acid as the chelating agent, the titanium chelate has the advantages of good stability, hydrolysis resistance, high polymerization activity, less impurity insoluble substances and wide applicable pH range. In some embodiments of the present disclosure, citric acid chelated titanium complex is used as an aqueous titanium catalyst to catalyze the esterification of terephthalic acid, ethylene glycol, and 1, 4-cyclohexanedimethanol.

In some embodiments, the reaction mixture may also include other types of catalysts, such as non-titanium-containing catalysts, including, for example, zinc acetate (Zn (C)₂H₃O₂)₂) Manganese acetate (Mn (C)₂H₃O₂)₂) Calcium acetate (Ca (C))₂H₃O₂)₂) Magnesium acetate (Mg (C)₂H₃O₂)₂) Cobalt acetate (Co (C)₂H₃O₂)₂) Or any combination of the above.

Simultaneously with or after the esterification reaction, polycondensation may be carried out in the same reaction tank to form a 1, 4-cyclohexanedimethanol-modified copolyester of polyethylene terephthalate or an ethylene glycol-modified copolyester of poly (1,4-cyclohexanedimethanol terephthalate). Among them, the polycondensation reaction is a transesterification reaction, and mainly acts to remove alcohols (e.g., remove Ethylene Glycol (EG)). In contrast, the esterification reaction functions as dehydration. The main product ester compound and the by-product water are generated in the reaction mixture due to the esterification reaction. The completion of the esterification reaction can be judged by visual observation when the reaction mixture is transparent and not turbid or when water is not distilled off any more. The reaction temperature of the esterification reaction may be 100 ℃ above the boiling point of water, thereby facilitating the removal of by-product water. The reaction temperature of the esterification reaction may be between 200 ℃ and 280 ℃. The reaction pressure for the esterification reaction may be between 725torr and 4145 torr.

The polycondensation reaction is an ester exchange reaction (dealcoholization) between terephthalic acid, ethylene glycol and an ester compound formed by esterification of 1, 4-cyclohexanedimethanol. The reaction temperature of the polycondensation reaction may be higher than the reaction temperature of the esterification reaction. The reaction temperature of the polycondensation reaction may be between 240 ℃ and 300 ℃. The reaction pressure of the polycondensation reaction may be lower than the reaction pressure of the esterification reaction. The reaction pressure of the polycondensation reaction can be between 400torr and 0.1 torr.

In one embodiment, a phosphorus-based stabilizer may be added to the reaction mixture after the esterification reaction and before the polycondensation reaction. The phosphorus based stabilizer may include octyl alcohol phosphate (isooctyl phosphate).

If the content ratio (mole ratio) of ethylene glycol and the sum of ethylene glycol and 1,4-cyclohexanedimethanol in the reaction tank is less than 50% (mole ratio of ethylene glycol/(ethylene glycol +1, 4-cyclohexanedimethanol) is less than 50%), the content of poly (1, 4-cyclohexanedimethylene terephthalate) in the generated final product is high, and the final product can be called as poly (1, 4-cyclohexanedimethylene terephthalate) ethylene glycol modified copolyester (PCTG). If the content ratio (mole ratio) of the ethylene glycol and the sum of the ethylene glycol and the 1,4-cyclohexanedimethanol in the reaction tank is more than 50% (the mole ratio of ethylene glycol/(ethylene glycol +1, 4-cyclohexanedimethanol) is more than 50%), the content of the polyethylene terephthalate in the generated final product is more, and the final product can be called as 1,4-cyclohexanedimethanol modified copolyester (PETG) of the polyethylene terephthalate.

In some embodiments of the present description, the ethylene glycol content in the reaction mixture is greater than 1, 4-cyclohexanedimethanol; and the titanium content of the aqueous titanium catalyst in the reaction mixture is more than 60 ppm. The number average molecular weight of the glycol-modified ethylene terephthalate copolyester formed by the reaction mixture is more than 12500, such as 12500-20000, or 12500-15000, or 12500-14000.

The glycol-modified ethylene terephthalate copolyester comprises 1,4-cyclohexanedimethanol units formed from 1,4-cyclohexanedimethanol, ethylene glycol units formed from ethylene glycol, and terephthalic acid units formed from terephthalic acid. In the glycol-modified ethylene terephthalate copolyester, the percentage of moles of 1,4-cyclohexanedimethanol units to the total moles of 1,4-cyclohexanedimethanol units and ethylene glycol units is at least 10 mole%, alternatively at least 20 mole%, alternatively at least 30 mole%.

The glycol-modified ethylene terephthalate copolyester produced in the above embodiments can be applied to industries such as medical, optical, electronic products, food/cosmetic packaging, signboard/storage rack, furniture, building materials, etc., to produce finished products such as (but not limited to) textiles, medical devices, containers, optical films, food/cosmetic packaging films, and pet bottles, which have excellent optical properties, high transparency, impact resistance, heat resistance, high gas barrier properties, gamma ray resistance, chemical resistance, and are easy to print and do not generate static electricity.

< example 1>

An atmospheric reaction tank was charged with 75.000 g (0.45 mole) of terephthalic acid (TPA), 61.589 g (0.99 mole) of Ethylene Glycol (EG), and 19.533 g (0.135 mole) of 1,4-Cyclohexanedimethanol (CHDM), and the condensation system was turned on. Then, 0.030 g (titanium content is 20ppm based on the dibasic acid) of citric acid chelated titanium complex (aqueous titanium-based catalyst, titanium content is 5%) and 0.125 g of 2 wt.% zinc acetate (non-titanium-containing catalyst, zinc content is 10ppm based on the dibasic acid) ethylene glycol solution were added, the temperature of the reaction tank was raised from room temperature to 230 ℃ while removing by-product water, and the temperature of the reaction tank was maintained at 230 ℃ to 260 ℃ until the reaction mixture was visually observed to be transparent and not turbid, and it was judged that the esterification reaction had been completed. Then, 0.028 g of a phosphorus stabilizer was added to the reaction mixture, and the temperature of the reaction vessel was raised to 270 ℃ while the reaction pressure in the reaction vessel was lowered to 18torr, and the reaction was carried out for 4 hours. Then, the reaction vessel was heated to 275 ℃ and the reaction pressure was reduced to 1torr, and the polycondensation reaction was completed in 4 hours. Thus obtaining the glycol modified ethylene terephthalate copolyester.

< example 2 and example 3>

The manufacturing method of the glycol-modified ethylene terephthalate copolyesters of example 2 and example 3 is the same as that of example 1. Except that the reaction mixture varied in the content of the citric acid chelated titanium complex. Wherein the reaction mixture of example 2 had a content of citric acid chelated titanium complex of 0.090 g (titanium content is 60ppm based on the dibasic acid); the reaction mixture of example 3 contained 0.120 g of the citric acid chelated titanium complex (titanium content relative to dibasic acid is 80 ppm).

< comparative examples 1to 3>

The method for manufacturing the glycol-modified ethylene terephthalate copolyesters of comparative examples 1to 3 is the same as in example 1. Except that a non-aqueous titanium catalyst was used as the titanium catalyst in the reaction mixture: tetrabutyl titanate (tetrabutyltantalate), and the content is varied. The reaction mixture of comparative example 1 had a tetrabutyl titanate content of 0.030 g (titanium content relative to the dibasic acid is 20 ppm); the reaction mixture of comparative example 2 had a tetrabutyl titanate content of 0.090 g (the content of titanium with respect to the dibasic acid was 60 ppm); the reaction mixture of comparative example 3 had a tetrabutyl titanate content of 0.120 g (titanium content relative to the dibasic acid is 80 ppm).

< comparative example 4>

56.059 g (0.338 mol) of terephthalic acid (TPA), 18.686 g (0.113 mol) of isophthalic acid (IPA) and 48.918 g (0.789 mol) of Ethylene Glycol (EG) were placed in the reaction tank, and the condensation system was started. Then 0.030 g (titanium content 20ppm based on dibasic acid) of citric acid chelated titanium complex (aqueous titanium based catalyst) and 0.125 g of 2 wt.% zinc acetate (non-titanium containing catalyst, zinc content 10ppm based on dibasic acid) ethylene glycol solution were added, the reaction tank temperature was raised from room temperature to 230 ℃ while removing by-product water, the reaction tank temperature was maintained at 230 ℃ to 260 ℃ until the esterification reaction was judged to have been completed when the reaction mixture was visually observed to be transparent and not cloudy. Then, the temperature of the reaction tank was increased to 270 ℃ and the reaction pressure of the reaction tank was decreased to 12torr, and the reaction was carried out for 1 hour. Then, the reaction vessel was heated to 285 ℃ and the reaction pressure was reduced to 1torr, and the polycondensation reaction was completed in 6 hours. Thus obtaining the binary acid modified ethylene glycol phthalate copolyester.

Next, the polyesters prepared in examples 1to 3 and comparative examples 1to 4 were sampled respectively for property analysis to calculate the number average molecular weight and hue (APHA color) value of each sample respectively.

< number average molecular weight test >

The polyesters prepared in examples 1to 3 and comparative examples 1to 4 were dissolved in a solvent of Tetrahydrofuran (THF), and the number average molecular weight was measured using Polystyrene (PS) as an analytical standard using a Gel Permeation chromatograph (Gel Permeation Chromatography) manufactured by Waters. Wherein the analysis conditions of the gel dialysis chromatograph comprise using a separation column with model number of KD-806M; the mobile phase was tetrahydrofuran and the flow rate was 1.0 milliliter per minute (ml/min). By means of the elution of the mobile phase, the high molecules with different molecular weights are separated in different detention time in the column. And Nuclear Magnetic Resonance (NMR) analysis was performed using a detector model RI-2410 manufactured by Waters corporation to obtain a one-dimensional hydrogen spectrum (R) ((R))¹HNMR) and the following were calculated from the area ratio of the peaks of the atlas:

the mole fraction (% by mol) of diethylene glycol units to diol units in the polyester is shown in Table 1. In examples 1to 3 and comparative examples 1to 3, this mole fraction is equal to the number of moles of diethylene glycol units divided by the total number of moles of 1,4-cyclohexanedimethanol units and ethylene glycol units multiplied by 100, expressed as a percentage. In comparative example 4, this mole fraction is equal to the number of moles of diethylene glycol units divided by the number of moles of ethylene glycol units multiplied by 100, expressed as a percentage.

The percentage of mole fraction of 1,4-cyclohexanedimethanol units relative to diol units in the polyester. In examples 1-3 and comparative examples 1-3, the percentage of this mole fraction is equal to the percentage of moles of 1,4-cyclohexanedimethanol units divided by the total number of moles of 1,4-cyclohexanedimethanol units and ethylene glycol units. The results of examples 1to 3 and comparative examples 1to 3 were all 30 mol%.

The polyester of comparative example 4 has a percentage (mol%) of the mole fraction of isophthalic acid units to diacid units that is equal to the number of moles of isophthalic acid units divided by the total number of moles of isophthalic acid units and terephthalic acid units. The result of comparative example 4 was 25 mol%.

< color analysis >

The yellowness index of a nearly transparent material was quantified by dissolving the polyesters prepared in examples 1to 3 and comparative examples 1to 4 in acetone (acetone), and measuring the hue value using a UV-VIS spectrophotometer (model number: SHIMADZU) and platinum-cobalt (Pt-Co) as an analytical standard. Among them, a smaller hue value indicates a better hue (a lower yellowing degree).

Table 1 shows the kinds and amounts of starting reaction raw materials and catalysts of the reaction mixtures for preparing polyesters in examples 1to 3 and comparative examples 1to 4, and the results of analyzing the properties of the polyesters.

TABLE 1

FIG. 1 is a graph showing the relationship between the content of titanium in the dibasic acid of the titanium-based catalyst and the number average molecular weight of the polyester produced in examples 1to 3 and comparative examples 1to 3.

FIG. 2 is a graph showing the relationship between the content of titanium in the dibasic acid of the titanium-based catalyst in examples 1to 3 and comparative examples 1to 3 and the mole fraction of diethylene glycol unit to diol unit of the polyester produced.

FIG. 3 is a graph showing the relationship between the content of the dibasic acid in titanium of the titanium catalyst and the hue value of the polyester obtained in examples 1to 3 and comparative examples 1to 3.

From table 1 and fig. 1to 3, the following results can be found. From the results of examples 1to 3 and comparative examples 1to 3 using the same polymerization monomers (TPA, EG, and CHDM), it was found that the use of an aqueous citric acid chelated titanium complex as a titanium catalyst has excellent characteristics of being not easily hydrolyzed and being thermally stable, does not lose catalytic activity in the by-product water produced by the esterification reaction, and can maintain highly active catalytic activity in the subsequent polycondensation reaction. The hue value (yellowing degree) of the glycol-modified ethylene terephthalate copolyester obtained in the example is lower than that of the comparative example under the same use amount of the titanium catalyst. In addition, the glycol-modified ethylene terephthalate copolyester obtained in the examples has a lower diethylene glycol unit content than that of the comparative examples at the same amount of the titanium-based catalyst. This indicates that the aqueous titanium catalyst used in the examples is not easily hydrolyzed during polycondensation reaction and loses its catalytic activity, and the polycondensation reaction time can be shortened. In particular, under the reaction condition of low-dose catalyst (for example, titanium accounts for less than 30ppm of dibasic acid), the effect of reducing the generation of the diethylene glycol unit in the polyester is more obvious: that is, the smaller the amount of the aqueous titanium catalyst (citric acid chelated titanium complex), the smaller the content of the diethylene glycol unit in the polyester, and the better the hue of the final product of the polyethylene terephthalate alcohol-modified copolymer. Thus, the problem of poor hue of the final product due to by-products can be suppressed by using an aqueous titanium citrate chelate complex as a titanium catalyst and preparing a polyethylene terephthalate alcohol-modified copolymer by an esterification method. In addition, the aqueous titanium catalyst of the embodiment can be dissolved in water, so that turbid insoluble substances can not be generated in the reaction mixture, and the glycol modified ethylene terephthalate copolyester can have good transparency. In addition, the glycol-modified ethylene terephthalate copolyesters of the examples have better mechanical properties and thermal stability.

From the results of comparative example 4 in Table 1, it was found that the aqueous titanium catalyst was not suitable for use in an esterification reaction system not containing 1,4-Cyclohexanedimethanol (CHDM).

The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.