Poly(1,4-cyclohexylenedimethylene 1,4-dimethyleneterephthalate) and process for its preparation

Abstract

The application belongs to the technical field of new materials, and particularly relates to a poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate and a preparation method thereof. The preparation method comprises the following steps: mixing terephthalic acid, 1,4-cyclohexanedicarboxylic acid and 1,3-propanediol, performing esterification under the action of a catalyst, and then placing the system in a 240 DEG C to 260 DEG C environment to perform polycondensation reaction for 1 h to 7 h, so as to obtain the poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate. The poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate has high intrinsic viscosity and degradability, and the highest intrinsic viscosity is 1.41 dL / g, the melting point is 160 DEG C to 220 DEG C, and TD5% is 360 DEG C to 380 DEG C.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new materials, and particularly relates to a poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester and a preparation method thereof. BACKGROUND

[0002] With the breakthrough of the technology of preparing 1,3-propanediol by biological fermentation method and chemical method on a large scale, it is possible to prepare poly-1,3-propanediol terephthalate on a large scale. The poly-1,3-propanediol terephthalate is also called PTT, which is a new type of thermoplastic polyester material and is widely used in the fields of textile and garment, carpet, engineering plastic and film. The PTT has the strength, toughness and heat resistance of polyethylene terephthalate (PET) and the processing advantage of polybutylene terephthalate (PBT), and the fiber made of PTT has higher tensile resilience and lower modulus than PET and PBT, and has the advantages of easy processing, easy dyeing and bulkiness of polyamide fiber PA. However, the processing temperature of the poly-1,3-propanediol terephthalate is relatively high, about 250 DEG C, and it does not have degradation performance, which limits its application.

[0003] In the synthesis process of PTT, the addition of aliphatic acids such as lactic acid and succinic acid makes the biodegradability of the copolyester weak, but the melting point of the obtained copolyester is greatly different from that of PTT. SUMMARY

[0004] In order to solve the above problems, the present application provides a poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester and a preparation method thereof. The present application uses 1,4-cyclohexanedicarboxylic acid as a comonomer to effectively improve the thermal stability and chemical resistance of the polyester material, and obtains a high intrinsic viscosity poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester.

[0005] In order to achieve the above purpose, the technical scheme of the present application is as follows.

[0006] The first aspect of the present application provides a preparation method of a poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester, comprising the following steps:

[0007] The terephthalic acid, 1,4-cyclohexanedicarboxylic acid and 1,3-propanediol are mixed, and esterification is carried out under the action of a catalyst. When the conversion rate is greater than 94%, the esterification is stopped, and after water removal, a system containing terephthalic acid-1,3-propanediol ester and 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester is obtained;

[0008] The system is placed at 240-260℃ for 1-7h to remove small molecule substances, and the poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester is obtained.

[0009] The present application introduces 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester structural unit into PTT high molecular chain, reduces the melting point of PTT high molecular chain, and improves the toughness and processing performance of the polymer from the molecular level. The direct esterification and polycondensation process is adopted to promote the polycondensation reaction balance and facilitate the formation of high polymer, and the polyester resin material with high intrinsic viscosity is prepared.

[0010] In another preferred embodiment, the molar ratio of the terephthalic acid and the 1,4-cyclohexanedicarboxylic acid is 0.1:1-1:0.1.

[0011] In another preferred embodiment, the molar ratio of the total terephthalic acid and 1,4-cyclohexanedicarboxylic acid to 1,3-propanediol is 1:1.1-2.0.

[0012] In another preferred embodiment, the catalyst is tetrabutyl titanate.

[0013] In another preferred embodiment, the molar ratio of the tetrabutyl titanate to the mixture is 0.3-0.9:260-870.

[0014] In another preferred embodiment, the temperature of the esterification reaction is 230-245℃, and the time is 1.5-4h. Preferably, the time of the esterification reaction is 3-4h.

[0015] In another preferred embodiment, the esterification reaction is carried out in a nitrogen atmosphere.

[0016] In another preferred embodiment, the removal of small molecule substances refers to the removal of 1,3-propanediol and oligomers by vacuum distillation.

[0017] The second aspect of the present application provides the poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester prepared by the preparation method of the poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester. Specifically, the structural formula of the poly-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester is shown in formula (1).

[0018] Formula (1);

[0019] The melting point of the copolyester is 160-220℃, the crystallization temperature is 110-181℃, and the thermal decomposition temperature TD5% is 360-380℃.

[0020] In another preferred embodiment, the intrinsic viscosity of the poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) is 0.8 dL / g to 1.4 dL / g.

[0021] Compared with the prior art, the present application has the following beneficial effects.

[0022] The present application selects 1,4-cyclohexanedicarboxylic acid as the third component monomer, and performs melt copolycondensation with terephthalic acid and 1,3-propanediol, so as to introduce 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester structural units in the structure, thereby being capable of adjusting the melting point and crystallization temperature of PTT, so that the melting point is 160-220 DEG C, the crystallization temperature is 110-181 DEG C, and the thermal decomposition temperature TD5% is 360-380 DEG C. The PTT is converted from an engineering plastic with high melting point, fast crystallization and brittle to a new generation of green polyester with low melting point, controllable crystallization, high toughness and viscosity, and easy degradation, thereby significantly widening the application boundary of the PTT in the fields of degradable packaging and high-end elastic fibers. The poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) in the present application has a degradation time of not more than half a year in soil in the preparation of degradable packaging.

[0023] The copolyester prepared in the present application is beneficial to improving the flexibility, brittleness, elongation, processability and degradability of the material, and the poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) prepared has high intrinsic viscosity, and the intrinsic viscosity is 0.8 dL / g to 1.4 dL / g. The present application adopts a direct esterification method, i.e., normal pressure esterification precondensation-high vacuum condensation-reduced pressure low-molecule removal, has strong controllability, short process flow, and small catalyst consumption, and can obtain copolyester with high intrinsic viscosity of 1.41 dL / g within a reaction period of 7-8 hours. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a nuclear magnetic hydrogen spectrum of the poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate).

[0025] Figure 2 It is a differential scanning calorimetry result graph of the poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate), wherein the curve a indicates a curve of temperature rising from -70 DEG C to 300 DEG C, and the curve b indicates a curve of temperature falling from 300 DEG C to -70 DEG C.

[0026] Figure 3 It is a thermogravimetric analysis graph of the poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate). DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0028] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative labor shall fall within the scope of protection of the present application. In the embodiments of the present application, the materials and equipment used, if not specifically stated, can be purchased in the market.

[0029] Embodiment 1: A preparation method of a poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) copolymer, comprising the following steps.

[0030] S1, 16.61 g, 100 mmol of terephthalic acid, 1.72 g, 10 mmol of 1,4-cyclohexanedicarboxylic acid, 11.4 g, 150 mmol of 1,3-propanediol and 0.17 g, 0.5 mmol of tetrabutyl titanate were placed in an esterification reaction bottle, the esterification temperature was controlled at 235°C under a nitrogen atmosphere, and esterification was carried out for 3 h. After water removal, a system containing 1,3-propanediol terephthalate and 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester was obtained.

[0031] S2, the system in S1 was vacuumized by a rotary vane vacuum pump, the reaction temperature was increased to 260°C, and after 4 h of polycondensation reaction, residual 1,3-propanediol and low-boiling oligomers were removed by reduced pressure distillation to prepare a poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) copolymer with a high intrinsic viscosity, and the intrinsic viscosity thereof was 1.11 dL / g.

[0032] Figure 1 The figure is a nuclear magnetic resonance spectrum of the poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) copolymer prepared in this embodiment 1. As can be seen from the figure, the prepared product is a poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) copolymer. Figure 3 The figure is a thermogravimetric analysis diagram of the poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) copolymer prepared in this embodiment 1.

[0033] Embodiment 2: A preparation method of a poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol terephthalate) copolymer, comprising the following steps.

[0034] S1, 16.61 g, 100 mmol of terephthalic acid, 3.44 g, 20 mmol of 1,4-cyclohexanedicarboxylic acid, 10.65 g, 140 mmol of 1,3-propanediol and 0.14 g, 0.4 mmol of tetrabutyl titanate were placed in an esterification reaction bottle, the esterification temperature was controlled at 230°C under a nitrogen atmosphere, and esterification was performed for 4 h. After water removal, a system containing terephthalic acid-1,3-propanediol ester and 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester was obtained.

[0035] S2, the system in S1 was vacuumized by a rotary vane vacuum pump, the reaction temperature was increased to 240°C, and the polycondensation reaction was maintained for 5 h. A small amount of 1,3-propanediol and low-boiling oligomers were removed by reduced pressure distillation to prepare a high intrinsic viscosity poly(terephthalic acid-1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester having an intrinsic viscosity of 0.90 dL / g.

[0036] Example 3: A method for preparing a poly(terephthalic acid-1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester, comprising the following steps.

[0037] S1, 16.61 g, 100 mmol of terephthalic acid, 3.44 g, 20 mmol of 1,4-cyclohexanedicarboxylic acid, 10.65 g, 140 mmol of 1,3-propanediol and 0.14 g, 0.4 mmol of tetrabutyl titanate were placed in an esterification reaction bottle, the esterification temperature was controlled at 230°C under a nitrogen atmosphere, and esterification was performed for 4 h. After water removal, a system containing terephthalic acid-1,3-propanediol ester and 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester was obtained.

[0038] S2, the system in S1 was vacuumized by a rotary vane vacuum pump, the reaction temperature was increased to 240°C, and the polycondensation reaction was maintained for 5 h. A small amount of 1,3-propanediol and low-boiling oligomers were removed by reduced pressure distillation to prepare a high intrinsic viscosity poly(terephthalic acid-1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester having an intrinsic viscosity of 0.90 dL / g.

[0039] Example 4: A method for preparing a poly(terephthalic acid-1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester, comprising the following steps.

[0040] S1, 16.61 g, 100 mmol of terephthalic acid, 3.44 g, 20 mmol of 1,4-cyclohexanedicarboxylic acid, 10.65 g, 140 mmol of 1,3-propanediol and 0.14 g, 0.4 mmol of tetrabutyl titanate were placed in an esterification reaction bottle, the esterification temperature was controlled at 230°C under a nitrogen atmosphere, and esterification was performed for 4 h. After water removal, a system containing terephthalic acid-1,3-propanediol ester and 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester was obtained.

[0041] S2, the system in S1 is pumped into vacuum by a rotary vane vacuum pump, the reaction temperature is increased to 265°C, and the polycondensation reaction is maintained for 2 h. A small amount of 1,3-propanediol and low-boiling oligomers are removed by vacuum distillation to prepare a high intrinsic viscosity poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester with an intrinsic viscosity of 0.92 dL / g.

[0042] Example 5: A method for preparing a poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester, comprising the following steps.

[0043] S1, 49.84 g, 300 mmol of terephthalic acid, 20.66 g, 120 mmol of 1,4-cyclohexanedicarboxylic acid, 34.38 g, 450 mmol of 1,3-propanediol, and 0.27 g, 0.8 mmol of tetrabutyl titanate are placed in an esterification reaction bottle, the esterification temperature is controlled at 235°C under a nitrogen atmosphere, and the esterification is performed for 1.5 h. After water removal, a system containing terephthalic acid-1,3-propanediol ester and 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester is obtained.

[0044] S2, the system in S1 is pumped into vacuum by a rotary vane vacuum pump, the reaction temperature is increased to 255°C, and the polycondensation reaction is maintained for 6 h. A small amount of 1,3-propanediol and low-boiling oligomers are removed by vacuum distillation to prepare a high intrinsic viscosity poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester with an intrinsic viscosity of 0.81 dL / g.

[0045] Example 6: A method for preparing a poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester, comprising the following steps:

[0046] S1, 49.84 g, 300 mmol of terephthalic acid, 20.66 g, 120 mmol of 1,4-cyclohexanedicarboxylic acid, 34.38 g, 450 mmol of 1,3-propanediol, and 0.27 g, 0.8 mmol of tetrabutyl titanate are placed in an esterification reaction bottle, the esterification temperature is controlled at 235°C under a nitrogen atmosphere, and the esterification is performed for 1.5 h. After water removal, a system containing terephthalic acid-1,3-propanediol ester and 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester is obtained.

[0047] S2, the system in S1 is pumped into vacuum by a rotary vane vacuum pump, the reaction temperature is increased to 255°C, and the polycondensation reaction is maintained for 6 h. A small amount of 1,3-propanediol and low-boiling oligomers are removed by vacuum distillation to prepare a high intrinsic viscosity poly(1,4-cyclohexanedicarboxylic acid-1,3-propanediol) copolyester with an intrinsic viscosity of 0.81 dL / g.

[0048] Comparative Example 1 is different from Example 1 in that 1,4-cyclohexanedicarboxylic acid is not added, and other steps are the same as those in Example 1. The prepared poly-1,3-propylene terephthalate has a intrinsic viscosity of 0.8 dL / g.

[0049] Compared with the poly-1,3-propylene terephthalate prepared in Comparative Example 1, the copolyester prepared in the application reduces the melting point and crystallization temperature of PTT macromolecules, and improves the mechanical properties of the polymer at the molecular level. At the same time, the copolyester prepared in the application has a high intrinsic viscosity.

[0050] The performance indicators of the poly-1,4-cyclohexanedicarboxylic acid-1,3-propylene glycol copolyester are tested as follows.

[0051] 1. The melting temperature and crystallization temperature are measured by differential scanning calorimetry, and the results are shown in Table 1. The instrument used is Mettler-Toledo DSC3 instrument. The test is performed on a 10 mg sample under a nitrogen atmosphere at a flow rate of 50 mL / min. Figure 2

[0052] First, the sample is heated from room temperature to 300°C at a rate of 10°C / min to eliminate thermal history. Then, it is cooled to -70°C at a rate of 10°C / min. Finally, the second heating scan is performed at a heating rate of 10°C / min, and the temperature is raised from -70°C to 300°C. All the melting temperature values are from the second scan, and the melting temperature is 203°C.

[0053] The thermal decomposition temperature is obtained by thermogravimetric analysis using a NETZSCH STA449 Jupiter instrument. The measurement is performed under a nitrogen atmosphere at a flow rate of 50 mL / min, and the temperature is raised at a rate of 10°C / min from 30°C to 850°C. The thermal decomposition temperature TD5% is 371°C.

[0054] 2. Degradation experiment

[0055] The degradation performance in acid and alkali solutions is mainly studied. PTT and PTTC-20% powders are placed in 1 mol / L NaOH and 1 mol / L HCl aqueous solutions for solution degradation experiments. The mass change is monitored periodically, and the results are shown in Tables 1 and 2. PTTC-20% is the poly-1,4-cyclohexanedicarboxylic acid-1,3-propylene glycol copolyester prepared in Example 2.

[0056] Table 1 Degradation effect under acidic conditions

[0057]

[0058] Table 2 Degradation effect under alkaline conditions ​

[0059]

[0060] As can be seen from Table 1, the mass loss of PTTC-20% in 1 mol / L HC1 solution was 9.3% in 77 days, which was similar to the mass loss of pure PTT, 9.8%. However, the molecular weight of PTT and PTTC-20% decreased by 3946 and 9729, respectively, indicating that the long molecular chain segments of the copolymer were more prone to breakage into small molecules. The results showed that the introduction of CDHA into the PTT chain could promote chain termination during the polymer degradation process. As shown in Table 2, the polymers also underwent degradation in NaOH alkaline solution. Their degradation rate was significantly faster than that in acidic solution. In 1 mol / L NaOH solution, the mass loss of PTTC-20% was 14.7% in 42 days, which was faster than the mass loss of PTTC-20% of 9.3% in 77 days. The degradation results of PTT and PTTC-20% in alkaline solution were similar to those in acidic solution.

[0061] The above description is only the preferred embodiment of the present application, and the above specific embodiments are not a limitation of the present application. Various modifications and changes can occur within the scope of the technical idea of the present application, and any modification, change or equivalent replacement made by those skilled in the art according to the above description shall fall within the scope of the present application.

Claims

1. A process for the preparation of a poly(l,4-cyclohexylenedimethylene 1,4- cyclohexanedicarboxylate 1,3-propanediol copolyester, characterized in that, The method comprises the following steps: terephthalic acid, 1,4-cyclohexanedicarboxylic acid and 1,3-propanediol are mixed to obtain a mixture, a catalyst is added to the mixture, an esterification reaction is carried out, the esterification reaction is stopped when the esterification rate is greater than 94%, and after water is removed, a system containing terephthalic acid-1,3-propanediol ester and 1,4-cyclohexanedicarboxylic acid-1,3-propanediol ester is obtained; the system is subjected to a polycondensation reaction at 240-260°C for 1-7h to remove small molecular substances, and the polyterephthalic acid-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester is obtained; the mass ratio of the terephthalic acid to the 1,4-cyclohexanedicarboxylic acid is 0.1-1:1-0.1; the total mass of the terephthalic acid and the 1,4-cyclohexanedicarboxylic acid to the mass of the 1,3-propanediol is 1:1.1-2.

0.

2. The process for the preparation of poly(l,4 cyclohexane dicarboxylic acid- 1,3 -propanediol) co-polyester according to claim 1, characterized in that, the catalyst is tetrabutyl titanate.

3. The process for the preparation of poly(l,4 cyclohexanediol-1,3 -propanediol) terephthalate copolyester according to claim 2, characterized in that, the mass ratio of the tetrabutyl titanate to the mixture is 0.3-0.9:260-870.

4. The process for the preparation of poly(l,4 cyclohexane dicarboxylic acid- 1,3 -propanediol co polyester) according to claim 1, characterized in that, the esterification reaction is carried out at 230-245°C for 1.5-4h.

5. The process for preparing poly(l,4 cyclohexane dicarboxylic acid-l,3- propanediol) co-polyester according to claim 1, characterized in that, the esterification reaction is carried out in a nitrogen atmosphere.

6. The process for the preparation of poly(l,4 cyclohexane dicarboxylic acid- 1,3 -propanediol co polyester) according to claim 1, characterized in that, the removal of small molecular substances refers to removal of 1,3-propanediol and oligomers by vacuum distillation.

7. A polyterephthalic acid-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester prepared by the method of any one of claims 1-6.

8. The poly(l,4 cyclohexanediol-1,3 -propanediol) terephthalate copolyester of claim 7, wherein, the intrinsic viscosity of the polyterephthalic acid-1,4-cyclohexanedicarboxylic acid-1,3-propanediol copolyester is 0.8-1.4 dL / g.

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