阅读说明：本技术 一种高回弹抗收缩可发泡改性聚酯珠粒及其制备方法 (High-resilience anti-shrinkage foamable modified polyester bead and preparation method thereof ) 是由 李金隆 冉启迪 王松林 朱楷 于 2021-08-31 设计创作，主要内容包括：本发明涉及聚酯领域,本发明公开了一种高回弹抗收缩可发泡改性聚酯珠粒及其制备方法,该可发泡改性聚酯包括：对苯二甲酸100份,乙二醇20～80份,除乙二醇外的二醇共聚单体10～50份,聚醚单体10～30份,催化剂0.02～0.12份,开孔剂0.01～2份。制备方法包括：(1)将对苯二甲酸、乙二醇和二醇共聚单体和催化剂混合进行酯化；(2)加入聚醚单体、开孔剂进行预缩聚、终缩聚反应,制得改性聚酯切片；(3)通过超临界流体发泡,制得成品。本发明利用二醇共聚单体破坏聚酯的链段规整性和结晶性能,降低加工温度；通过聚醚单体使改性聚酯具有较好的回弹性。通过加入开孔剂的提高泡沫的抗收缩性能。(The invention relates to the field of polyester, and discloses high-resilience anti-shrinkage foamable modified polyester beads and a preparation method thereof, wherein the foamable modified polyester comprises the following components in parts by weight: 100 parts of terephthalic acid, 20-80 parts of ethylene glycol, 10-50 parts of glycol comonomer except the ethylene glycol, 10-30 parts of polyether monomer, 0.02-0.12 part of catalyst and 0.01-2 parts of pore-forming agent. The preparation method comprises the following steps: (1) mixing terephthalic acid, ethylene glycol and glycol comonomer with a catalyst for esterification; (2) adding a polyether monomer and a pore-forming agent to carry out pre-polycondensation and final polycondensation reaction to prepare a modified polyester chip; (3) foaming with supercritical fluid to obtain the final product. The invention utilizes the diol comonomer to destroy the chain segment regularity and the crystallization property of the polyester, and reduces the processing temperature; the modified polyester has better rebound resilience through the polyether monomer. The shrinkage resistance of the foam is improved by adding the cell opening agent.)

1. A high-resilience anti-shrinkage foamable modified polyester bead is characterized in that: the feed comprises the following raw materials in parts by weight:

100 parts of terephthalic acid, namely terephthalic acid,

20-80 parts of ethylene glycol,

10-50 parts of glycol comonomer except ethylene glycol,

10-30 parts of a polyether monomer,

0.02 to 0.12 portion of catalyst,

0.01-2 parts of a pore-forming agent.

2. The high resilience shrinkage-resistant expandable modified polyester bead as claimed in claim 1, wherein:

the diol comonomer is selected from one or more of propylene glycol, butylene glycol, pentanediol, neopentyl glycol, 1, 4-cyclohexanedimethanol, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, and diethylene glycol;

the polyether monomer is selected from one or more of polyoxypropylene diol, polyoxypropylene triol, polytetrahydrofuran diol and tetrahydrofuran-propylene oxide copolymerized diol.

3. The high resilience shrinkage-resistant expandable modified polyester bead as claimed in claim 2, wherein:

the diol comonomer is selected from one or more of propylene glycol, neopentyl glycol and 1, 4-cyclohexanedimethanol;

the polyether is selected from one or more of polyoxypropylene diol, polyoxypropylene triol and polytetrahydrofuran diol, and the number average molecular weight is 800-4000.

4. The high resilience shrinkage-resistant expandable modified polyester bead as claimed in claim 1, wherein: the pore-forming agent is one or more of ALLCHEM-3350, GK-350D and Ortegol-501.

5. The high resilience shrinkage-resistant expandable modified polyester bead as claimed in claim 1, wherein: the catalyst is selected from one or more of two-dimensional composite titanium heterogeneous polyester catalyst, ethylene glycol antimony, antimony trioxide, antimony acetate, tetrabutyl titanate, tetraisopropyl titanate and zinc acetate.

6. A process for the preparation of high resilience shrink-resistant expandable modified polyester beads as claimed in any one of claims 1 to 5, characterized in that: the method comprises the following steps:

(1) adding terephthalic acid, ethylene glycol, glycol comonomer and a catalyst into a polymerization reactor to carry out esterification reaction;

(2) adding a polyether monomer and a pore-forming agent, and sequentially carrying out pre-polycondensation and final polycondensation to obtain modified polyester chips;

(3) and placing the modified polyester chips into a foaming device, and filling a foaming agent medium to carry out supercritical fluid foaming to prepare the high-resilience anti-shrinkage foamable modified polyester beads.

7. The method of claim 6, wherein: in the step (1), the preheating temperature of the polymerization reactor is 60-150 ℃, the esterification reaction temperature is 200-260 ℃, and the pressure is 0-0.35 MPa.

8. The method of claim 6, wherein: in the step (2), the condition of the pre-polycondensation reaction is that the vacuum pumping is carried out until the absolute pressure is below 1000Pa, and the pre-polycondensation temperature is 260-280 ℃; the final polycondensation temperature is 265-295 ℃, the pressure is 0-300Pa, and the final polycondensation reaction time is 10-120 min.

9. The method of claim 6, wherein: in the step (3), the foaming agent is one or two of carbon dioxide and nitrogen.

10. The production method according to claim 6 or 9, characterized in that: in the step (3), the foaming temperature is 80-200 ℃, the foaming pressure is 10-30MPa, the pressure maintaining time is 5-120min, the pressure relief time is controlled at 0-10s, and the cooling time is controlled at 0-30 min.

Technical Field

The invention relates to the field of polyester, in particular to high-resilience anti-shrinkage foamable modified polyester beads and a preparation method thereof,

background

Polyethylene terephthalate (PET) is widely used in the fields of fiber weaving, packaging and the like due to its excellent mechanical properties, high temperature resistance and aging resistance. The PET has higher melting point, higher crystallinity, lower melt strength and narrow foaming process window. The PET foaming method comprises a kettle pressure method, an extrusion method, a micropore foaming method and the like, the extrusion method is adopted for polyester foaming in the industry at present, and the obtained product is a hard foam plate and is mainly applied to the field of wind power. The production method of bead foam is a batch kettle type foaming method, and the principle of the method is that a foaming agent is introduced into a kettle, the foaming agent fully permeates into a polymer blank at a certain temperature and pressure, and gas is diffused in the pressure relief process to expand a polymer so as to form a foaming structure. Compared with other polymers, the PET molecular structure has stronger rigidity, so that the foamed PET is suitable for being used as a sandwich material with a sandwich structure and meets the requirements of light weight and high strength. In addition, the foaming material has better heat-insulating property, and in addition, the PET has the characteristics of oil resistance, high temperature resistance, chemical corrosion resistance, easy recovery and the like, so the foaming PET has great application prospect in the fields of packaging, refrigerator inner plates, wall body heat preservation, cold chain logistics, automobiles, aerospace industry and the like.

PET is a linear crystalline high polymer material, is easily degraded at high temperature, the viscosity and strength of a melt are sharply reduced after the temperature is higher than a melting point, gas cannot be kept in the melt in a bubble expansion process to cause cell breakage, and the central cell cannot be fully cooled to avoid collapse of the central cell before crystallization and solidification in a cooling process, so that the conventional polyester resin has the inherent defect of foaming, and has low foaming ratio and poor elasticity.

Patent CN102993421B adopts polyhydric alcohol, polybasic acid or polybasic acid anhydride as chain extender to directly melt and polymerize, then prepares long chain branching PET with high melt strength through solid-phase tackifying, has high melt index and high shear viscosity, and finally prepares PET foam board through extrusion. The fluidity is poor after chain extension, the processing temperature is high, the requirement on equipment is high, and the prepared foam plate has high rigidity and no elasticity. Patent CN102993421A provides a foamable poly (terephthalic acid)The preparation method of the acid ethylene glycol copolyester is characterized in that other dibasic acids and dihydric alcohols except terephthalic acid and ethylene glycol, and polybasic acid, polybasic acid anhydride or polyhydric alcohol containing more than two functional groups are added in the esterification reaction, wherein the adding ratio of the ethylene glycol to the other glycols is 3-5: 1. The copolyester prepared by the method can be applied to extrusion foaming, but still has a crystalline structure, the melting points are all above 200 ℃, the processing temperature is still high, the foaming multiplying power is limited, and the elasticity is poor. Patent CN109476869A proposes a method for preparing ester-based elastomer foam molded body, which is used for replacing polyurethane in a part of high-end market. In the method, isophthalic acid is added into a polyester hard segment to further destroy the regularity, although the melting point is reduced to below 200 ℃, a certain crystallinity is still kept to maintain high resilience, the corresponding product density is higher, and the lowest foam density in the embodiment is 59kg/m³However, no clear improvement is proposed to combat the shrinkage problem.

In summary, the performance and processing mode of the existing PET foaming material are single, the foaming temperature is high, the foaming ratio is low, and the problems of elasticity and shrinkage resistance are less researched.

Disclosure of Invention

The invention provides a high-resilience anti-shrinkage foamable modified polyester bead and a preparation method thereof, aiming at solving the problems of high processing temperature, low foaming ratio, poor elasticity, no shrinkage resistance and the like in the existing polyester foaming process. On one hand, other diol comonomers are added into the polyester to destroy the chain segment regularity and crystallization performance of the polyester, so that the melting interval is widened, the processing temperature is greatly reduced, and the foaming window is enlarged; on the other hand, the polyether monomer is added to introduce a soft segment structure into the modified polyester, so that the modified polyester has better resilience. Finally, the anti-shrinkage performance of the foam is improved by adding the cell opening agent in the polymerization process, and the obtained foam has high foaming ratio, high resilience and anti-shrinkage performance.

The specific technical scheme of the invention is as follows:

in a first aspect, the invention provides high-resilience anti-shrinkage foamable modified polyester beads, which comprise the following raw materials in parts by weight:

100 parts of terephthalic acid, namely terephthalic acid,

20-80 parts of ethylene glycol,

10-50 parts of glycol comonomer except ethylene glycol,

10-30 parts of a polyether monomer,

0.02 to 0.12 portion of catalyst,

0.01-2 parts of a pore-forming agent.

Firstly, other diol comonomers except ethylene glycol are added into the polyester, and a random copolymerization structure is formed by the competition of the other diol comonomers with the ethylene glycol, so that the original regularity of a PET chain segment is damaged, the crystallinity of the modified polyester is reduced, the melting point of the modified polyester is reduced, the processing temperature is greatly reduced, and the foaming window is expanded. The randomness, the processing temperature and the foaming performance of the modified polyester can be controlled by adjusting the addition proportion of the monomer diol. Secondly, the polyether monomer is added to introduce a soft segment structure into the modified polyester, and the content of the soft segment in the modified polyester can be controlled by controlling the adding amount of the polyether monomer, so that the modified polyester has better rebound resilience. In addition, the present inventors have found during their research and development that the amount of comonomer (diol comonomer and polyether monomer) added needs to be strictly controlled, and when the amount is too high, a block structure mainly composed of comonomer is easily formed under the combined effect of monomer concentration and reactivity, resulting in formation of a new crystalline region, increasing crystallinity and deteriorating foamable performance. Therefore, the comonomer content should be controlled within the above reasonable range.

In addition, the polyester foaming bead reduces the surface tension of the modified polyester, improves the opening rate of the foaming polyester, improves the specific surface area, balances the internal and external pressure intensity of the foaming bead and improves the anti-shrinkage performance of the foaming polyester by adding the opening agent; the finally prepared foam has high foaming ratio, high resilience and shrinkage resistance.

Preferably, the diol comonomer is selected from one or more of propylene glycol, butylene glycol, pentylene glycol, neopentyl glycol, 1, 4-cyclohexanedimethanol, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, and diethylene glycol; further preferred is one or more of propylene glycol, neopentyl glycol and 1, 4-cyclohexanedimethanol.

The reason why the monomers such as propylene glycol, neopentyl glycol and 1, 4-cyclohexanedimethanol are further preferred is that the difference between the reactivity of the monomers and that of ethylene glycol is small, a random copolymerization structure is easily formed, the damage to the regularity and the crystallinity of a polyester chain segment is more effective, the utilization rate in the reaction process is high, and the content is controllable.

Preferably, the polyether monomer is selected from one or more of polyoxypropylene diol, polyoxypropylene triol, polytetrahydrofuran diol and tetrahydrofuran-oxypropylene copolyol; further preferably one or more of polyoxypropylene diol, polyoxypropylene triol and polytetrahydrofuran diol, and has a number average molecular weight of 800-4000.

According to the different molecular weights of the selected polyether monomers, the different properties of the modified polyester can be controlled.

Preferably, the pore-forming agent is one or more of ALLCHEM-3350, GK-350D and Ortegol-501.

Preferably, the catalyst is selected from one or more of two-dimensional composite titanium heterogeneous polyester catalyst, ethylene glycol antimony, antimony trioxide, antimony acetate, tetrabutyl titanate, tetraisopropyl titanate and zinc acetate.

In a second aspect, the invention provides a preparation method of high-resilience anti-shrinkage expandable modified polyester beads, which comprises the following steps:

(1) terephthalic acid, ethylene glycol, glycol comonomer and catalyst are added to a polymerization reactor for esterification.

(2) Adding a polyether monomer and a pore-forming agent, and carrying out pre-polycondensation and final polycondensation reaction to obtain the modified polyester chip.

(3) Placing the modified polyester chips into a foaming device, filling a foaming agent medium into the foaming device for supercritical fluid foaming to prepare the high-resilience anti-shrinkage foamable modified polyester beads. The density of the obtained expandable modified polyester beads ranges from 25 to 200kg/m³。

The invention adopts an in-situ polymerization mode, is simple and easy to operate, can directly foam the product, does not need subsequent processing such as reaction extrusion and the like, simplifies the production flow and reduces the energy consumption compared with the prior polyester rigid foam beads; the foaming process of the method provided by the invention obviously reduces the preparation cost of the polyester foam, shortens the processing time, and is simple and efficient in operation process.

Preferably, in the step (1), the preheating temperature of the polymerization reactor is 60-150 ℃, the esterification reaction temperature is 200-260 ℃ and the pressure is 0-0.35 MPa.

Preferably, in the step (2), the conditions of the pre-polycondensation reaction are that the vacuum is pumped to the absolute pressure of less than 1000Pa, and the pre-polycondensation temperature is 260-280 ℃; the final polycondensation temperature is 265-295 ℃, the pressure is 0-300Pa, and the final polycondensation reaction time is 10-120 min.

Preferably, in the step (2), the intrinsic viscosity of the modified polyester chip is 0.50 to 0.95 dl/g.

Preferably, in the step (3), the foaming agent is one or two of carbon dioxide and nitrogen.

Preferably, in the step (3), the foaming temperature is 80-200 ℃, the foaming pressure is 10-30MPa, the pressure maintaining time is 5-120min, the pressure relief time is controlled to be 0-10s, and the cooling time is controlled to be 0-30 min.

In the foaming process, the key steps are the control of pressure maintaining time and a pressure relief mode, and unreasonable pressure maintaining time can cause material bonding collapse and foaming failure; the pressure relief is not uniform, too fast can cause the foam cells to be too small and have low multiplying power, too slow can cause the foam cells to be too large, and the foam rebound rate is low.

Compared with the prior art, the invention has the following technical effects:

(1) according to the invention, other diol comonomers except ethylene glycol are added into the polyester, and the prepared high-resilience anti-shrinkage foamable modified polyester bead is low-melting-point or amorphous random modified polyester, is convenient to process and has a wide foaming interval. Meanwhile, polyether monomers are added to form polyether blocks, so that the polyester foam beads have high resilience.

(2) The foaming ratio of the polyester foaming bead prepared by the invention is controllable, and the thermal property and the melt strength of the raw materials are changed by changing the contents of the diol monomer and the polyether polyol in the formula, so that the foaming ratio of the foaming bead is controlled.

(3) According to the polyester expanded bead, the surface tension of the modified polyester is reduced, the opening rate of the polyester expanded bead is improved, the specific surface area is improved, the internal and external pressure of the expanded bead is balanced, and the anti-shrinkage performance of the polyester expanded bead is improved by adding the opening agent.

(4) The invention adopts an in-situ polymerization mode, is simple and easy to operate, can directly foam the product, does not need subsequent processing such as reaction extrusion and the like, simplifies the production flow and reduces the energy consumption compared with the prior polyester rigid foam beads.

(5) The foaming process of the invention obviously reduces the preparation cost of the polyester foaming beads, shortens the processing time and has simple and efficient operation process.

Detailed Description

The present invention will be further described with reference to the following examples.

General examples

The high-resilience anti-shrinkage foamable modified polyester bead comprises the following raw materials in parts by weight: 100 parts of terephthalic acid, 20-80 parts of ethylene glycol, 10-50 parts of glycol comonomer except the ethylene glycol, 10-30 parts of polyether monomer, 0.02-0.12 part of catalyst and 0.01-2 parts of pore-forming agent.

Preferably, the diol comonomer is selected from one or more of propylene glycol, butylene glycol, pentylene glycol, neopentyl glycol, 1, 4-cyclohexanedimethanol, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, and diethylene glycol; further preferred is one or more of propylene glycol, neopentyl glycol and 1, 4-cyclohexanedimethanol.

Preferably, the polyether monomer is selected from one or more of polyoxypropylene diol, polyoxypropylene triol, polytetrahydrofuran diol and tetrahydrofuran-oxypropylene copolyol; further preferred is one or more of polyoxypropylene diol, polyoxypropylene triol and polytetrahydrofuran diol, and the polyether selected has a number average molecular weight of 800-4000.

Preferably, the pore-forming agent is one or more of ALLCHEM-3350, GK-350D and Ortegol-501.

Preferably, the catalyst is selected from one or more of two-dimensional composite titanium heterogeneous polyester catalyst, ethylene glycol antimony, antimony trioxide, antimony acetate, tetrabutyl titanate, tetraisopropyl titanate and zinc acetate.

The preparation method of the two-dimensional composite titanium heterogeneous polyester catalyst comprises the following steps:

(a) mixing titanium carbide material MXene (Ti)₃C₂T_x、Ti₂CT_x、(Ti_0.5，Nb_0.5)₂CT_x、Zr₃C₂T_x、Ti₃CNT_x、Mo₂TiC₂T_xOr Mo₂Ti₂C₃T_x(ii) a T represents MXene surface group (-OH, -F, ═ O, etc.), x is positive integer, adding into corrosive agent (mixed solution of hydrochloric acid and fluorine salt, hydrochloric acid concentration is 6-9mol/L), molar ratio of fluorine salt and titanium carbide material MXene is 1: 7.5-9. Stirring sequentially (30-45 deg.C, 24-48h) under protective atmosphere, washing, drying, ultrasonic stripping, and alkali solution (4-10 wt% NaOH, KOH or Mg (OH))₂Solution) treatment (20-45 ℃ for 1-3h), centrifugation, washing and drying to obtain the alkalized two-dimensional MXene.

(b) Dissolving a guanidine modifier (guanidine, guanidine hydrochloride or guanidine-naphthalenesulfonic acid) in ethylene glycol to obtain a 10-30 wt% guanidine solution; dispersing the alkalized two-dimensional MXene in ethylene glycol to obtain 10-20 wt% of alkalized two-dimensional MXene dispersion liquid; and uniformly mixing the guanidine solution and the MXene dispersion liquid, wherein the mass ratio of the guanidine modifier to the alkalized two-dimensional MXene is 1: 5-10. Adjusting pH to 7-11 with pH regulator (triethanolamine, 2-aminomethyl propanol), and grinding (25-45 deg.C, 1-3h, grinding medium is mixed zirconium bead with diameter of 0.3-0.7mm, and filling ratio is 60-75%) to obtain grinding dispersion.

(c) Performing first-step centrifugation (1000-; storing at 5-10 deg.C in the absence of oxygen.

A preparation method of high-resilience anti-shrinkage expandable modified polyester beads comprises the following steps:

(1) terephthalic acid, ethylene glycol, glycol comonomer and catalyst are added into a polymerization reactor with the preheating temperature of 60-150 ℃ for esterification reaction, the esterification reaction temperature is 200-260 ℃ and the pressure is 0-0.35 MPa.

(2) Adding polyether monomer and pore opening agent, vacuumizing to below 1000Pa, heating to 260-280 deg.C for pre-polycondensation, and final polycondensation at 265-295 deg.C under 0-300Pa for 10-120min to obtain modified polyester chip with intrinsic viscosity of 0.50-0.95 dl/g.

(3) Placing the modified polyester slices into a foaming device, filling a foaming agent medium (carbon dioxide and/or nitrogen) for supercritical fluid foaming, heating to 80-200 ℃, keeping the temperature and pressure for 5-120min under 10-30MPa, then decompressing for 0-10s, and cooling for 0-30min to obtain the high-resilience anti-shrinkage foamable modified polyester bead.

Example 1

Adding 100 parts of terephthalic acid, 60 parts of ethylene glycol, 30 parts of 1, 3-butanediol and 0.05 part of ethylene glycol antimony into a 2.5L reaction kettle, stirring at 100 ℃ for 15min, and introducing N₂The esterification reaction was started at 230 ℃ and 0.30 MPa. After the water discharge was completed, 10 parts of polytetrahydrofuran (2000) and 33500.02 parts of pore former ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the kettle at 280 ℃ under reduced vacuum. After the vacuum meter reaches-101 kPa, high vacuum is pumped, after the vacuum degree reaches below 100Pa, current readings are recorded, and the reaction is carried out for 90min from the beginning of the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 200 ℃ and 15 MPa. And (3) after the constant temperature and the constant pressure are maintained for 20min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Comparative example 1 (different from example 1 in that 1, 3-butanediol was replaced with ethylene glycol in the same mass part) 100 parts of terephthalic acid, 90 parts of ethylene glycol and 0.05 part of ethylene glycol antimony were put into a 2.5L reactor, stirred at 100 ℃ for 15min and then N was introduced₂The esterification reaction was started at 230 ℃ and 0.30 MPa. After the water discharge is finished, 10 parts of polytetrahydrofuran (2000) and a pore forming agent ALLCH are addedEM33500.02 parts, stirred for 10min, pulled low vacuum while the kettle temperature was set to 280 ℃. And (4) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current reading after the vacuum degree reaches below 100Pa, and reacting for 90 min. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 200 ℃ and 15 MPa. And (3) after the constant temperature and the constant pressure are maintained for 20min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Comparative example 2 (different from example 1 in that polytetrahydrofuran (2000) was not added)

Adding 100 parts of terephthalic acid, 60 parts of ethylene glycol, 30 parts of 1, 3-butanediol and 0.05 part of ethylene glycol antimony into a 2.5L reaction kettle, stirring at 100 ℃ for 15min, and introducing N₂The esterification reaction was started at 230 ℃ and 0.30 MPa. After the water discharge was completed, 33500.02 parts of an air-hole opener ALLCHEM was added, and the mixture was stirred for 10min, and then a low vacuum was applied while the temperature of the kettle was set to 280 ℃. And (4) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current reading after the vacuum degree reaches below 100Pa, and reacting for 90 min. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 200 ℃ and 15 MPa. And (3) after the constant temperature and the constant pressure are maintained for 20min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Comparative example 3 (different from example 1 in that excessive polytetrahydrofuran (2000) was added from 10 parts to 50 parts)

Adding 100 parts of terephthalic acid, 60 parts of ethylene glycol, 30 parts of 1, 3-butanediol and 0.05 part of ethylene glycol antimony into a 2.5L reaction kettle, stirring at 100 ℃ for 15min, and introducing N₂The esterification reaction was started at 230 ℃ and 0.30 MPa. After the water discharge was completed, 50 parts of polytetrahydrofuran (2000) and 33500.02 parts of pore former ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the kettle at 280 ℃ under reduced vacuum. After the vacuum meter reaches-101 kPa, high vacuum is pumped, after the vacuum degree reaches below 100Pa, current readings are recorded, and the reaction is carried out for 30min from the beginning of the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to a temperature of 200 ℃ andthe pressure is 15 MPa. And (3) after the constant temperature and the constant pressure are maintained for 20min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Comparative example 4 (different from example 1 in that ALLCHEM3350 as a pore former was not added)

Adding 100 parts of terephthalic acid, 60 parts of ethylene glycol, 30 parts of 1, 3-butanediol and 0.05 part of ethylene glycol antimony into a 2.5L reaction kettle, stirring at 100 ℃ for 15min, and introducing N₂The esterification reaction was started at 230 ℃ and 0.30 MPa. After the water discharge is finished, 10 parts of polytetrahydrofuran (2000) are added, the mixture is stirred for 10min, the vacuum is pumped, and meanwhile, the temperature of the kettle is set to 280 ℃. After the vacuum meter reaches-101 kPa, high vacuum is pumped, after the vacuum degree reaches below 100Pa, current readings are recorded, and the reaction is carried out for 90min from the beginning of the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 200 ℃ and 15 MPa. And (3) after the constant temperature and the constant pressure are maintained for 20min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Example 2

100 parts of terephthalic acid, 80 parts of ethylene glycol, 20 parts of neopentyl glycol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂The esterification reaction was started at 230 ℃ and 0.30 MPa. After the completion of the water discharge, 10 parts of polytetrahydrofuran (2000) and 33500.02 parts of ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the reactor at 280 ℃ under reduced vacuum. And (4) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current reading after the vacuum degree reaches below 100Pa, and reacting for 90 min. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 180 ℃ and 15 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Example 3

100 parts of terephthalic acid, 80 parts of ethylene glycol, 20 parts of 1, 4-cyclohexanedimethanol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂Starting the ester at 230 ℃ and 0.30MPaAnd (4) carrying out a reaction. After the water discharge was completed, 10 parts of polytetrahydrofuran (2000) and 33500.02 parts of pore former ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the reactor at 280 ℃ under reduced vacuum. And (4) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current reading after the vacuum degree reaches below 100Pa, and reacting for 90 min. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 140 ℃ and 15 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Example 4

100 parts of terephthalic acid, 70 parts of ethylene glycol, 30 parts of 1, 4-cyclohexanedimethanol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 00 ℃ for 15min and then N is introduced₂The esterification reaction was started at 250 ℃ and 0.3 MPa. After the water discharge was completed, 10 parts of polyoxypropylene triol and 33500.02 parts of cell opener ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the kettle at 280 ℃ under reduced vacuum. And (3) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current readings after the vacuum degree reaches below 100Pa, and reacting for 90min from the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 130 ℃ and 15 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Comparative example 5 (different from example 4 in that the pot pressure foaming conditions were 70 ℃ C., 15MPa)

100 parts of terephthalic acid, 70 parts of ethylene glycol, 30 parts of 1, 4-cyclohexanedimethanol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂The esterification reaction was started at 230 ℃ and 0.3 MPa. After the water discharge was completed, 10 parts of polyoxypropylene triol and 33500.02 parts of cell opener ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the kettle at 280 ℃ under reduced vacuum. And (3) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current readings after the vacuum degree reaches below 100Pa, and reacting for 90min from the current rise. Stopping the reaction, discharging and pelletizing. Placing the obtained slices in a foaming kettle, and fillingAdding foaming agent CO₂Preheating to 70 ℃ and 15 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Comparative example 6 (different from example 4 in that the foaming conditions under still pressure were 85 ℃ C., 6MPa)

100 parts of terephthalic acid, 70 parts of ethylene glycol, 30 parts of 1, 4-cyclohexanedimethanol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂The esterification reaction was started at 230 ℃ and 0.3 MPa. After the water discharge was completed, 10 parts of polyoxypropylene triol and 33500.02 parts of cell opener ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the kettle at 280 ℃ under reduced vacuum. And (3) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current readings after the vacuum degree reaches below 100Pa, and reacting for 90min from the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 85 ℃ and 6 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Example 5

100 parts of terephthalic acid, 75 parts of ethylene glycol, 5 parts of 1, 3-propanediol, 25 parts of 1, 4-cyclohexanedimethanol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂The esterification reaction was started at 230 ℃ and 0.3 MPa. After the water discharge was completed, 10 parts of polyoxypropylene triol and 33500.02 parts of cell opener ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the kettle at 280 ℃ under reduced vacuum. And (3) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current readings after the vacuum degree reaches below 100Pa, and reacting for 90min from the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 120 ℃ and 15 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Comparative example 7 (different from example 5 in that the addition of an excess of ALLCHEM3350, from 0.02 parts to 2.5 parts)

100 parts of terephthalic acid, 75 parts of ethylene glycol, 5 parts of 1, 3-propanediol, 25 parts of 1, 4-cyclohexanedimethanol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂The esterification reaction was started at 230 ℃ and 0.3 MPa. After the water discharge was completed, 10 parts of polyoxypropylene triol and 33502.5 parts of cell opener ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the kettle at 280 ℃ under reduced vacuum. And (3) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current readings after the vacuum degree reaches below 100Pa, and reacting for 90min from the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 120 ℃ and 15 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Example 6

100 parts of terephthalic acid, 80 parts of ethylene glycol, 20 parts of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂The esterification reaction was started at 230 ℃ and 0.3 MPa. After the water discharge was completed, 10 parts of polyoxypropylene triol and 33500.2 parts of cell opener ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while keeping the temperature of the kettle at 280 ℃ under reduced vacuum. And (3) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current readings after the vacuum degree reaches below 100Pa, and reacting for 90min from the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 180 ℃ and 15 MPa. Keeping the constant temperature and the constant pressure for 15min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Example 7

100 parts of terephthalic acid, 70 parts of ethylene glycol, 30 parts of 1, 4-cyclohexanedimethanol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂The esterification reaction was started at 230 ℃ and 0.3 MPa. After the water discharge was completed, 20 parts of polyoxypropylene glycol and 33500.02 parts of ALLCHEM were added thereto, and the mixture was stirred for 10 minutes while applying a low vacuumThe pot temperature was set to 280 ℃. And (3) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current readings after the vacuum degree reaches below 100Pa, and reacting for 90min from the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 130 ℃ and 15 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Example 8

100 parts of terephthalic acid, 70 parts of ethylene glycol, 30 parts of 1, 4-cyclohexanedimethanol and 0.05 part of ethylene glycol antimony are added into a 2.5L reaction kettle, stirred at 100 ℃ for 15min and then N is introduced₂The esterification reaction was started at 230 ℃ and 0.3 MPa. After the water discharge was completed, 10 parts of polyoxypropylene glycol, 10 parts of polytetrahydrofuran (2000), and 0.2 part of zinc acetate were added, stirred for 10min, and then a vacuum was applied while the temperature of the reactor was set to 280 ℃. And (3) vacuumizing after the vacuum instrument reaches-101 kPa, recording the current readings after the vacuum degree reaches below 100Pa, and reacting for 90min from the current rise. Stopping the reaction, discharging and pelletizing. Placing the prepared slices in a foaming kettle, and filling foaming agent CO₂Preheating to 130 ℃ and 15 MPa. And (3) after keeping the constant temperature and the constant pressure for 10min, quickly relieving the pressure for 3s to the normal pressure through a manual valve, cooling for 10min, opening the foaming kettle and taking out a sample.

Example 9 (different from example 8 in that 0.05 part of ethylene glycol antimony was replaced with an ethylene glycol solution (catalyst content: 0.002 part) of a two-dimensional composite titanium-based heterogeneous polyester catalyst)

The preparation method of the two-dimensional composite titanium heterogeneous polyester catalyst comprises the following steps:

(1) preparing 1L of 9mol/L hydrochloric acid solution, adding LiF with the total molar weight of 1.93mol, stirring to dissolve, adding 50g of raw material Ti₃AlC₂. Then, the atmosphere was replaced with argon gas, the mixture was sealed, and the mixture was stirred continuously at 40 ℃ for 48 hours and then washed with pure water until the pH was 7. After centrifugal separation, vacuum drying at 60 deg.C for 12h, adding the obtained powder into oxygen-free water at a mass ratio of 1: 300, ultrasonically treating for 1h, centrifuging at 3500rpm for 1h, adding KOH into the obtained suspension to make KOH mass concentration 6 wt%, continuously stirring at 25 deg.C for 2h, centrifuging, and mixingThe sediment was washed to pH 7 and finally centrifuged and dried in vacuo for 12h to give alkalised two dimensional MXene.

(2) Dissolving 3g of guanidine in 12g of ethylene glycol to prepare a solution with the mass concentration of 20 wt%; 30g of the above-mentioned alkalized two-dimensional MXene was dispersed in 270g of ethylene glycol at a mass concentration of 10% by weight, and the guanidine solution was added to the MXene dispersion with stirring. Adjusting the pH value of the MXene dispersion liquid to 8 by using triethanolamine, and adjusting the temperature to 25 ℃; and fully grinding for 3 hours by using a grinder.

(3) The ground dispersion was centrifuged at 1500rpm for 30min in a centrifuge, the resulting sediment was removed and the suspension was centrifuged in the next step. And centrifuging at 8000rpm for 20min to obtain precipitate, and adjusting mass concentration of the obtained suspension to 8 wt% with ethylene glycol.

The catalyst is a catalyst self-developed by the applicant, and the preparation principle and the advantages thereof are as follows: firstly, corroding by using a corrosion reagent to remove an Al layer on MXene, simultaneously intercalating MXene by using metal ions in the corrosion reagent, stripping in an ultrasonic mode to obtain a large number of fragmented two-dimensional MXene, and then replacing Ti-F sites on the surface of MXene by using alkali to obtain the alkalified two-dimensional MXene with a large number of Ti-OH functional groups. Because the Ti-OH sites on the surface of the alkalized two-dimensional MXene are electronegative and are easy to react with amino compounds to form hydrogen bonds, the guanidine modifier is adopted to grind and modify the surface of the MXene, so that the grafting modification purpose can be achieved, and in the grinding process of the MXene, the solvent and the small guanidine molecules can be inserted into the MXene layers, the interlayer acting force is further weakened, so that the two-dimensional MXene can be further stripped, part of the MXene can be broken into small pieces of MXene in collision, and more terminal titanium sites are exposed. The two effects can improve the dispersibility of the MXeen catalyst, so that the polycondensation time is short, and the reaction speed is faster and more uniform. After modification, not only can guanidine be introduced to improve catalytic activity, but also a synergistic effect can be generated between the Ti-based site and the guanidine, so that the reaction process is balanced while the electron transfer is promoted to accelerate the reaction rate, the surface electrical property is favorably changed, the contact reaction between the Ti-based site and a hydroxylated substance in the polymerization process is blocked, the generation of a colored organic titanium compound is inhibited, and the hue deviation of polyester is avoided. In addition, the doping of a small amount of two-dimensional material is also beneficial to enhancing the strength of the polyester. Compared with an antimony catalyst, the catalyst is green and nontoxic, and can realize similar catalytic effect with a very small addition amount.

Performance testing

The foamed modified polyesters obtained in the examples and the comparative examples were subjected to performance tests, wherein:

(1) intrinsic viscosity: polyester samples were dissolved in phenol: in a mixed solvent of tetrachloroethane at a mass ratio of 3: 2, the intrinsic viscosity of the sample was measured at room temperature using an Ubbelohde viscometer.

(2) Melting point and glass transition temperature: and (3) adopting a differential scanning calorimeter to scan a sample for heating and cooling cycles between 30 and 280 ℃, and determining the melting point and the glass transition temperature of the polymer.

(3) The rebound resilience: and (3) measuring by adopting a falling ball rebound method, dropping the metal ball to the same specification sample plate made of different foaming beads from the same height, measuring the rebound height and calculating the rebound rate.

(4) Shrinkage rate: the density of the expanded beads was measured by the drainage method, the same beads were left at normal temperature for 24 hours, the density of the expanded beads was measured again, and the shrinkage was calculated.

The formulation and test data for the foam modified polyesters of each example and comparative example are shown in Table 1.

TABLE 1 comparison of sample parameters for each example and comparative example

And (4) conclusion: it is clear from examples 1, 2, 3 and 6 that the thermal properties of the products obtained using different diol comonomers are different, in terms of glass transition temperature, melting point and foaming temperature. Wherein, the 1, 3-butanediol product has melting point, the highest foaming temperature and poor foaming effect; the polymerization reaction activity of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol is low, more cell opening agents are needed to be added to improve the foaming ratio, the cost is improved, and although the product is of a random structure, the heat resistance is good, so the foaming temperature is high, and the foaming effect is poor; the neopentyl glycol foaming effect is good, and the regularity of polyester can be better destroyed due to the multi-branched structure of the neopentyl glycol; a completely random structure is formed after 1, 4-cyclohexanedimethanol is used, but compared with 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, the molecular structure has better flexibility, weakened rigidity, greatly reduced foaming temperature and high foaming ratio.

From examples 3 and 4, it can be seen that the foaming temperature and the foaming effect of the product can be changed by adjusting the contents of the monomeric diol and the polyether polyol, and the foaming ratio can be effectively improved by increasing the comonomer within a certain addition range.

From examples 4 and 5, it can be seen that the randomness of the molecular structure can be further enhanced, the foaming temperature can be reduced, and the foaming multiplying power can be improved by selecting two proper comonomers for compounding.

As can be seen from examples 3, 4, 7 and 8, the selected 3 preferred polyether polyols can achieve better foaming effect, but different polyether polyols have different elasticity for the synthesized modified polyester due to different chain segment softening degrees, wherein the modified polyester synthesized by the polyoxypropylene diol and the polyether polyol compounded with the polytetrahydrofuran (2000) has the best elasticity, and the modified polyester synthesized by the polyoxypropylene triol has the poor elasticity.

It is understood from examples 8 and 9 that when a two-dimensional composite titanium-based heterogeneous polyester catalyst is used as the catalyst, the amount of the catalyst can be reduced and the same effect as that of ethylene glycol antimony can be obtained.

As can be seen from the comparison between example 1 and comparative example 1, the glass transition temperature and the melting point are both significantly reduced after the addition of the comonomer, and the polymerization product obtained by using only ethylene glycol has regular chain segments, good crystallinity, a higher melting point, no swelling at the same foaming temperature, and no foaming effect.

It is understood from comparison of comparative example 2 with example 1 that the absence of addition of polyether polyol results in a smaller decrease in glass transition temperature and melting point of the modified polyester and a large decrease in resilience.

As can be seen from comparison of comparative example 3 with example 1, after excessive polyether polyol is added, the glass transition temperature of the modified polyester is obviously reduced, the foaming temperature is reduced, the rebound resilience is greatly improved, and the foaming ratio is lower.

The comparative example 4 is compared with the example 1, and it is understood that the shrinkage resistance of the cell opener to the foamed polyester is remarkably improved.

As can be seen from comparison between comparative example 5 and example 4, the modified polyester prepared by the invention can be foamed in a wider temperature range, meanwhile, the foaming effect is greatly influenced by the foaming temperature, and if the temperature is too low, the polymer cannot sufficiently soften and dissolve the foaming agent, so that the multiplying power is obviously reduced.

As can be seen from comparison of comparative example 6 with example 4, the foaming effect is also significantly affected by the pressure, and the pressure during foaming is too low, CO₂The solubility in the polymer is reduced, and meanwhile, the pressure difference in the pressure relief process is too small, so that the polymer cannot be fully expanded by the diffusion of the foaming agent, and the foaming ratio is reduced.

As is clear from comparison of comparative example 7 with example 5, the addition of an excessive amount of the additive causes a slight increase in the intrinsic viscosity and the glass transition temperature, and the magnification is slightly decreased at the same foaming temperature, so that the optimum foaming temperature thereof is presumably higher than 130 ℃ and the energy consumption is increased.

From the data of examples 1 to 9 and comparative examples 1 to 7, it is clear that the above requirements can be satisfied in all aspects only by the embodiments within the preferred range of the present invention, and that an optimized high elasticity shrinkage resistant foamable modified polyester can be obtained. The change of the mixture ratio and the replacement/addition/subtraction of the raw materials can bring corresponding negative effects.

The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.