In-situ polymerized polyester nucleating agent master batch and preparation method of heat-resistant regenerated polyester

Abstract

The invention discloses an in-situ polymerization polyester nucleating agent master batch and a preparation method of heat-resistant regenerated polyester, and belongs to the technical field of new regenerated polyester materials. The composite nucleating agent master batch of the ionic polymer and the active nanoparticles is synthesized through in-situ polymerization and is blended with the regenerated PET to obtain the heat-resistant regenerated polyester, so that the crystallization rate and the crystallinity of the regenerated PET are remarkably improved, the crystal structure of the regenerated PET is improved, and a remarkable effect can be achieved by adding a small amount of the composite nucleating agent master batch into the PET. The method is simple in process, controllable in cost and suitable for the fields with high requirements on heat resistance, such as high-temperature food packaging and electronic and electric appliance parts.

Description

Technical Field

[0001] The invention relates to the technical field of recycled polyester material preparation, and in particular to a method for preparing in-situ polymerized and heat-resistant recycled polyester. Background Art

[0002] PET is a thermoplastic polyester, primarily synthesized through direct esterification of terephthalic acid with ethylene glycol or transesterification of dimethyl terephthalate with ethylene glycol. The global annual production of PET polyester exceeds 79 million tons. It is widely used in food packaging due to its non-toxicity, high transparency, good stability within a wide temperature range, and resistance to acid and alkali corrosion. However, conventional PET materials have limitations in terms of heat resistance, with a low heat deformation temperature, which restricts their application in high-temperature environments. For example, in the food packaging field, for products that require high-temperature sterilization, ordinary PET materials are difficult to meet the requirements. Although there are various existing methods to improve the heat resistance of PET, there are still many shortcomings. For example, the addition of conventional nucleating agents has little effect or has a negative impact on other properties of the material; and methods such as blending and modification have problems such as uneven dispersion and complex processing.

[0003] The thermal properties of PET are closely related to its crystallinity. PET molecules possess strong crystallization potential, but due to the rigidity of their molecular chains and their high glass transition temperature, which hinder their movement, PET is only a semi-crystalline material. To address PET's slow crystallization rate, research is ongoing on PET modification, and a variety of nucleating agents have been developed to accelerate PET crystallization. For example, in the field of inorganic nucleating agents, in-depth research has been conducted on boron nitride, carbon nanotubes, and zinc oxide. By optimizing their particle size and surface treatment, their dispersibility in PET has been improved. In the field of organic nucleating agents, sodium linoleate, sodium benzenesulfonate metal salts, and ionic polymers can significantly improve PET's crystallization properties, accelerate crystallization rates, and increase crystallinity. Regarding preparation processes, BASF, a global leader in chemicals and materials, has a rich portfolio of nucleating agent products and advanced technological applications. For example, the nucleating agent Irgastab NA 287 can improve material rigidity, impact resistance, hardness, and heat distortion temperature, and is suitable for materials such as PP, PE, and nylon. The development of heat-resistant recycled polyester, through the introduction of efficient nucleating agents and optimization of the preparation process, not only improves the crystallinity and heat resistance of recycled PET, but also expands the application range of recycled materials, such as for use in high-end applications such as high-temperature food packaging and electronic components, thereby promoting the "upcycling" model, reducing raw material waste, and promoting the improvement of the circular economy system. However, the melting point range of this material is 380-400°C, which means that the high-temperature resistance performance of the processing equipment is higher and the cost is increased. There is still room for improvement in the refinement of the preparation process and the stability of product quality. Summary of the Invention

[0004] The present invention aims to solve technical problems such as slow crystallization rate and poor heat resistance of existing PET materials, and provides a method for preparing in-situ polymerized polyester nucleating agent masterbatch and heat-resistant recycled polyester. The polyester nucleating agent masterbatch prepared by this method is added to PET, which can significantly improve the heat resistance of the PET material and increase the heat deformation temperature to above 120 degrees, while ensuring that other properties of the material are not damaged. The preparation process is simple and the cost is controllable.

[0005] To achieve the above objectives, the present invention provides a method for preparing an in-situ polymerized polyester nucleating agent masterbatch and a heat-resistant recycled polyester. The specific technical scheme is as follows:

[0006] An in-situ polymerized polyester nucleating agent masterbatch, composed of an ionic polymer and a nano-oxide; wherein the ionic polymer is a sulfonate copolyester having a sodium ion content greater than 10% mol / mol in the polymer molar ratio;

[0007] The nano-oxide is a combination of one or more of zinc oxide, zirconium oxide, and silicon dioxide. As a preferred technical solution, the particle size of the nano-oxide is in the range of 5-100 nm. As a preferred technical solution, a method for preparing an in-situ polymerized polyester nucleating agent masterbatch and heat-resistant recycled polyester comprises the following steps:

[0008] Step S1: adding sodium 5-sulfoisophthalate and ethylene glycol in a certain ratio into a reactor equipped with a fractionating column, stirring and heating to a predetermined temperature to carry out an esterification reaction, condensing and collecting water produced during the reaction, and controlling the reaction rate to obtain product 1;

[0009] Step S2: adding terephthalic acid and ethylene glycol in a certain proportion into a reaction vessel and mixing them uniformly, and conducting an esterification reaction under certain reaction conditions, to obtain Product 2 after the reaction. Step S3: placing a certain amount of ethylene glycol into a reaction vessel, adding a certain amount of nano-oxide into the vessel, and uniformly dispersing the nano-oxide in the ethylene glycol. Then, adding the mixed solution of ethylene glycol and nano-oxide into a sand mill equipped with zirconium beads with a diameter of less than 1 mm and grinding for 2 hours to obtain Additive 1.

[0010] Step S4: adding the product 1 obtained in step S1 and the product 2 obtained in step S2 into a polycondensation kettle in a certain ratio, and adding additive 1 at the same time, then heating the polycondensation kettle to 220° C. to remove excess ethylene glycol, then further heating the kettle to 270° C., polycondensing under vacuum conditions for 1 hour, and pressing out with nitrogen to obtain polyester nucleating agent masterbatch;

[0011] Step S5: adding the polyester nucleating agent masterbatch prepared in step S4 to the light-regenerated PET chips or recycled polyester bottle chips at a certain mass ratio, melt-blending in a twin-screw extruder, and granulating to obtain heat-resistant recycled polyester chips;

[0012] As a preferred technical solution, the input amounts of 5-sodium sulfoisophthalate and ethylene glycol in step S1 are 50 parts of 5-sodium sulfoisophthalate and 150 parts of ethylene glycol; the predetermined temperature is 180° C.; and the reaction rate is 75-80%.

[0013] As a preferred technical solution, the input ratio of phthalic acid and ethylene glycol in step S2 is 1:1.1-2.0 mol / mol; the reaction conditions are: pressure controlled at 0-0.3 MPa, and temperature around 250°C.

[0014] As a preferred technical solution, the input amounts of the nano-oxide and ethylene glycol in step S3 are: 20 parts of nano-oxide and 80 parts of ethylene glycol respectively.

[0015] As a preferred technical solution, the mass ratio of Product 1 to Product 2 in step S4 is 0.6-1:1; the amount of Additive 1 added is 0.1-0.3 of the total mass of Product 1 and Product 2. As a preferred technical solution, the amount of polyester nucleating agent masterbatch added in step S5 is 1-3.5% of the mass of the light-treated recycled PET chips or recycled polyester bottle flakes; the intrinsic viscosity of the light-treated recycled PET chips or recycled polyester bottle flakes is 0.60-0.90 dl / g.

[0016] As a preferred technical solution, the container, tableware or sheet made of the heat-resistant recycled polyester obtained in step S5 can withstand high temperatures above 120°C.

[0017] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0018] The invention significantly improves the heat resistance of recycled PET materials, so that it can meet the needs of scenarios with high heat resistance requirements such as high-temperature sterilization food packaging and high-temperature components of electronic appliances, and broadens the application field of recycled PET; through the in-situ polymerization process, the inorganic ultrafine powder is evenly dispersed in the copolyester, effectively avoiding the problem of powder agglomeration in traditional blending methods, and the addition amount is small, which has little effect on the mechanical properties of the recycled polyester; at the same time, the preparation method is simple, does not require complex equipment and special processes, has low cost, and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the DSC melting crystallization peak of the regenerated heat-resistant polyester of the present invention;

[0020] Figure 2 These are photos of examples and comparative examples of the recycled heat-resistant polyester of the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0023] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0024] Example 1

[0025] This embodiment provides a method for preparing an in-situ polymerized polyester nucleating agent masterbatch and a heat-resistant recycled polyester, and the specific steps are as follows:

[0026] Step S1: 50 g of 5-sodium sulfoisophthalate and 150 g of ethylene glycol were added to a reactor equipped with a fractionating column, and the mixture was stirred and heated to 180° C. for esterification. The water produced during the reaction was condensed and collected, and the reaction rate was controlled to 75-80%, thereby obtaining Product 1.

[0027] Step S2: 166 g of terephthalic acid and 124 g of ethylene glycol were added to a reaction vessel and mixed evenly, and an esterification reaction was carried out at 0.2 MPa and 250° C. to obtain Product 2 after the reaction was completed;

[0028] Step S3: 80 g of ethylene glycol was placed in a container, 20 g of nano-oxide having a particle size of 20 nm was added to the container, and the nano-oxide was uniformly dispersed in the ethylene glycol. The mixed ethylene glycol and nano-oxide solution was then added to a sand mill equipped with zirconium beads having a diameter of less than 1 mm and ground for 2 hours to obtain Additive 1.

[0029] Step S4: 112 g of the product 1 obtained in step S1 and 40 g of the product 2 obtained in step S2 were weighed and added to a polycondensation kettle, and 20 g of the additive 1 was added at the same time. The polycondensation kettle was then heated to 220° C. to remove excess ethylene glycol, and then the temperature was further raised to 270° C. and polycondensed under vacuum for 1 hour. The polycondensation was then pressed out with nitrogen to obtain a polyester nucleating agent masterbatch. The intrinsic viscosity of the nucleating masterbatch was tested to be 0.39 dl / g.

[0030] Step S5: adding the polyester nucleating agent masterbatch prepared in step S4 at a mass ratio of 1% to glossy recycled PET with an intrinsic viscosity of 0.69 dl / g, melt-blending in a twin-screw extruder, and pelletizing to obtain heat-resistant recycled polyester chips;

[0031] Example 2

[0032] The process of this embodiment is basically the same as that of embodiment 1, except that:

[0033] In step 4, the mass of product 1 added was 56 g, and the intrinsic viscosity of the obtained polyester nucleating agent masterbatch was 0.45 dl / g.

[0034] Example 3

[0035] The process of this embodiment is basically the same as that of embodiment 1, except that:

[0036] In step 4, the mass of product 1 added was 28 g, and the intrinsic viscosity of the obtained polyester nucleating agent masterbatch was 0.47 dl / g.

[0037] Example 4

[0038] The process of this embodiment is basically the same as that of embodiment 1, except that:

[0039] In step 3, nano zinc oxide was replaced by nano zirconium oxide, and the intrinsic viscosity of the obtained polyester nucleating agent masterbatch was 0.40 dl / g.

[0040] Example 5

[0041] The process of this embodiment is basically the same as that of embodiment 1, except that:

[0042] In step 3, nano zinc oxide was replaced with nano silicon oxide, and the intrinsic viscosity of the obtained polyester nucleating agent masterbatch was 0.42 dl / g.

[0043] Example 6

[0044] The process of this embodiment is basically the same as that of embodiment 1, except that:

[0045] In step 5, the mass ratio of the polyester nucleating agent masterbatch was changed to 2%.

[0046] Example 7

[0047] The process of this embodiment is basically the same as that of embodiment 1, except that:

[0048] In step 5, the mass ratio of the polyester nucleating agent masterbatch was changed to 3%.

[0049] Example 8

[0050] The process of this embodiment is basically the same as that of embodiment 1, except that:

[0051] In step 5, the mass ratio of the polyester nucleating agent masterbatch was changed to 4%.

[0052] Example 9

[0053] The process of this embodiment is basically the same as that of embodiment 1, except that:

[0054] In step 5, the mass ratio of the polyester nucleating agent masterbatch was changed to 5%.

[0055] Comparative Example 1

[0056] The process of this comparative example is basically the same as that of Example 1, except that:

[0057] The product 1 and product 2 of step S4 and the additive 1 were directly blended in a conventional blending manner without in-situ polymerization to prepare the polyester nucleating agent masterbatch. Other conditions were the same as those in Example 1.

[0058] Comparative Example 2

[0059] The process of this comparative example is basically the same as that of Example 1, except that:

[0060] Only the sulfonate copolyester nucleating agent was added, and other conditions were the same as those in Example 1.

[0061] Comparative Example 3

[0062] The process of this comparative example is basically the same as that of Example 1, except that:

[0063] Only nano zinc oxide nucleating agent was added, and other conditions were the same as those in Example 1.

[0064] Comparative Example 4

[0065] The process of this comparative example is basically the same as that of Example 1, except that:

[0066] No nucleating agent was added, and other conditions were the same as in Example 1.

[0067] The heat-resistant recycled polyester chips prepared in Examples 1-9 and Comparative Examples 1-4 were subjected to relevant tests:

[0068] The DSC test procedure is as follows: 8 mg of sample is placed in an aluminum crucible and placed in a differential scanning calorimeter. In a nitrogen atmosphere, the temperature is increased from 35°C to 280°C at a rate of 10°C / min, held at that temperature for 4 minutes to remove thermal history, and then cooled to 35°C at a rate of 20°C / min. The first cooling curve is recorded. Tmc is the crystallization temperature, and ΔHf is the melting enthalpy.

[0069]

[0070] Note: “○” represents no deformation, “√” represents slight deformation, and “×” represents obvious deformation.

[0071] Comparative DSC testing of the materials of Examples 1-3 and Comparative Example 1 revealed that the crystallization temperature of the materials of Examples 1-3 was approximately 20°C higher than that of the material of Comparative Example 1, demonstrating the significant advantages of the polyester nucleating agent masterbatch prepared by in-situ polymerization of the present invention. Comparative DSC testing of the materials of Example 1 and Examples 6-9 revealed that the crystallization temperature of the material of Example 1 was approximately 10°C higher than that of the materials of Examples 6-9, demonstrating that adding 1-3% by weight of the nucleating masterbatch is the optimal choice for achieving optimal crystallization.

[0072] In summary, the present invention significantly improves the heat resistance of recycled PET materials, enabling them to meet the needs of scenarios with high heat resistance requirements such as high-temperature sterilization food packaging and high-temperature components of electronic appliances, thereby broadening the application fields of recycled PET. Through the in-situ polymerization process, the inorganic ultrafine powder is evenly dispersed in the copolyester, effectively avoiding the problem of powder agglomeration in the traditional blending method, and the addition amount is small, which has little effect on the mechanical properties of the recycled polyester. At the same time, the preparation method is simple, does not require complex equipment and special processes, has low cost, and has good industrial application prospects.

[0073] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An in-situ polymerized polyester nucleating agent masterbatch, characterized in that: It is composed of an ionic polymer and nano-oxide; Wherein, the ionic polymer is a sodium ion content of the polymer molar ratio is greater than 10% mol / mol sulfonate copolyester; The nano-oxide is one or more combinations of zinc oxide, zirconium oxide and silicon dioxide.

2. The in-situ polymerized polyester nucleating agent masterbatch according to claim 1, characterized in that , the particle size of the nano oxide is in the range of 5-100nm.

3. A method for preparing an in-situ polymerized polyester nucleating agent masterbatch and heat-resistant recycled polyester according to any one of claims 1 to 2, comprising the following steps: Step S1: adding sodium 5-sulfoisophthalate and ethylene glycol in a certain ratio into a reactor equipped with a fractionating column, stirring and heating to a predetermined temperature to carry out an esterification reaction, condensing and collecting water produced during the reaction, and controlling the reaction rate to obtain product 1; Step S2: adding terephthalic acid and ethylene glycol in a certain ratio into a reaction vessel and mixing them evenly, and performing an esterification reaction under certain reaction conditions to obtain product 2 after the reaction is completed; Step S3: placing a certain amount of ethylene glycol in a reaction container, adding a certain amount of nano-oxide to the container to uniformly disperse the nano-oxide in the ethylene glycol, and then adding the mixed solution of ethylene glycol and nano-oxide to a sand mill equipped with zirconium beads with a diameter of less than 1 mm and grinding for 2 hours to obtain additive 1; Step S4: adding the product 1 obtained in step S1 and the product 2 obtained in step S2 into a polycondensation kettle in a certain ratio, and adding additive 1 at the same time, then heating the polycondensation kettle to 220° C. to remove excess ethylene glycol, then further heating the kettle to 270° C., polycondensing under vacuum conditions for 1 hour, and pressing out with nitrogen to obtain polyester nucleating agent masterbatch; Step S5: adding the polyester nucleating agent masterbatch prepared in step S4 to the light-regenerated PET chips or recycled polyester bottle chips at a certain mass ratio, melt-blending in a twin-screw extruder, and granulating to obtain heat-resistant recycled polyester chips.

4. The method for preparing an in-situ polymerized polyester nucleating agent masterbatch and heat-resistant recycled polyester according to claim 3, characterized in that: In step S1, the input amounts of 5-sodium sulfoisophthalate and ethylene glycol are 50 parts of 5-sodium sulfoisophthalate and 150 parts of ethylene glycol; the predetermined temperature is 180° C.; and the reaction rate is 75-80%.

5. The method for preparing an in-situ polymerized polyester nucleating agent and heat-resistant recycled polyester masterbatch according to claim 3, characterized in that: In step S2, the input ratio of phthalic acid and ethylene glycol is 1:1.1-2.0 mol / mol; the reaction conditions are: the pressure is controlled at 0-0.3 MPa and the temperature is about 250°C.

6. The method for preparing an in-situ polymerized polyester nucleating agent masterbatch and heat-resistant recycled polyester according to claim 3, characterized in that: The input amounts of the nano-oxide and ethylene glycol in step S3 are: 20 parts of nano-oxide and 80 parts of ethylene glycol respectively.

7. The method for preparing an in-situ polymerized polyester nucleating agent masterbatch and heat-resistant recycled polyester according to claim 3, characterized in that: In step S4, the input mass ratio of product 1 and product 2 is 0.6-1:1; the input mass ratio of additive 1 is 0.1-0.3 of the total mass of product 1 and product 2.

8. The method for preparing an in-situ polymerized polyester nucleating agent masterbatch and heat-resistant recycled polyester according to claim 3, characterized in that: The polyester nucleating agent masterbatch in step S5 is added in an amount of 1-3.5% of the mass of the light-regenerated PET chips or recycled polyester bottle chips; the intrinsic viscosity of the light-regenerated PET chips or recycled polyester bottle chips is 0.60-0.90 dl / g.

9. The method for preparing an in-situ polymerized polyester nucleating agent masterbatch and heat-resistant recycled polyester according to claim 3, characterized in that: The container, tableware or sheet made of the heat-resistant recycled polyester obtained in step S5 can withstand high temperatures above 120°C.

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