CN118812779A - A sodium sulfonate ionomer nucleating agent for polyethylene terephthalate and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of organic synthesis, and particularly relates to a sodium sulfonate ionomer nucleating agent for polyethylene glycol terephthalate, which is sodium vinylsulfonate hydroxyethyl methacrylate ionomer or sodium vinylsulfonate glycidyl methacrylate ionomer, and is obtained by reacting sodium vinylsulfonate monomer, X monomer and initiator, wherein the X monomer is hydroxyethyl methacrylate monomer or glycidyl methacrylate monomer. The nucleating agent is applied to modification of PET, so that the melting crystallization temperature of PET is increased, the crystallization rate is accelerated, the degradation of PET can be effectively reduced, a new way is provided for the application of PET as engineering plastic, and the application range of PET is widened.

Description

A sodium sulfonate ionomer nucleating agent for polyethylene terephthalate and its preparation method and application

Technical Field

The invention belongs to the technical field of organic synthesis, and in particular relates to a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate and a preparation method and application thereof.

Background Art

Polyethylene terephthalate, referred to as PET, is a thermoplastic polyester that can be divided into non-engineering plastics grade and engineering plastics grade. PET has excellent physical and mechanical properties within a certain temperature range, such as high rigidity, high impact strength, stability to more organic solvents and inorganic acids, etc., so the application field of PET is very wide. However, due to the presence of benzene rings in the main chain of the PET molecule, the rigidity of the molecular chain is relatively strong, and the ester group with strong polarity is connected to the benzene ring to form a conjugated structure, which further increases the rigidity of the molecular chain and increases the resistance to molecular movement. In this case, although PET has a flexible -CH ₂ CH ₂ -, its structure is too short, so the PET molecular chain is still mainly rigid, which leads to an increase in the crystallization temperature of PET and a decrease in the crystallization rate, which in turn leads to difficulty in processing PET during injection molding, high mold temperature, and long production cycle, which limits the application of PET in the field of engineering plastics. Therefore, improving the crystallization rate has become one of the key technologies for industrial modification of PET.

Adding nucleating agents during the PET molding process is an effective method to improve the crystallization properties of PET. The nucleating agents used in PET are generally divided into: inorganic, organic and polymer types. Among them, inorganic nucleating agents have poor dispersibility and poor nucleation effect; organic nucleating agents are mostly hydroxy acid salts, and their nucleation mechanism is chemical nucleation, that is, they react with PET during the processing process to form nucleation sites for PET crystallization, thereby promoting PET crystallization, but will cause PET chain breakage; polymer nucleating agents are mostly ionomers, such as Suryln resin developed by DuPont and AClyn ethylene acrylic acid ionomer developed by Honeywell, which are all effective nucleating agents for PET. At present, most of the effective PET nucleating agents on the market are hydroxy acid salts, and other potential PET nucleating agents need to be developed.

Summary of the invention

The present invention is intended to provide a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, in order to provide a new PET nucleating agent and expand the selection range of PET nucleating agents on the market.

In order to achieve the above object, the scheme of the present invention is: a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate hydroxyethyl methacrylate ionomer or sodium vinyl sulfonate glycidyl methacrylate ionomer, the structure of the sodium vinyl sulfonate hydroxyethyl methacrylate ionomer is shown in formula (I), and the structure of the sodium vinyl sulfonate glycidyl methacrylate ionomer is shown in formula (II);

In formula (I) and formula (II), m and n are both natural numbers, and the value range of m/n is 0.1 to 9.

The present invention also provides a method for preparing a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, comprising the following steps:

S1, mixing sodium vinyl sulfonate monomer, X monomer and the first solvent to obtain a mixed solution, dissolving the initiator in the second solvent, and then adding the mixture dropwise, heating to 70-80° C., and reacting for 3-6 hours; wherein the X monomer is hydroxyethyl methacrylate monomer or glycidyl methacrylate monomer;

S2. After the reaction is completed, the crude product is spin-dried to obtain a crude product, which is dissolved and placed in a precipitant for precipitation, and then purified and dried to obtain a nucleating agent product.

Optionally, in step S1, the molar ratio of the sodium vinyl sulfonate monomer to the X monomer is 1:0.1-9, and the molar ratio of the sum of the moles of the sodium vinyl sulfonate monomer and the X monomer to the mole of the initiator is 100:1-0.1.

Optionally, in step S1, the first solvent is an ethanol aqueous solution, in which the volume ratio of anhydrous ethanol to water is 1 to 10:3; and the second solvent is deionized water.

Optionally, in step S1, the initiator is sulfate-bisulfite.

Optionally, in step S2, the precipitant is anhydrous ethanol.

Optionally, in step S1, the initiator is dissolved in the second solvent and then added dropwise to the mixed solution at a dropping rate of 4 to 8 s/drop.

The sodium sulfonate ionomer nucleating agent for polyethylene terephthalate is used in the modification of polyethylene terephthalate. When used, the sodium sulfonate ionomer nucleating agent for polyethylene terephthalate is uniformly mixed with polyethylene terephthalate, melt-blended at 250-270° C. for 4-7 minutes, extruded and granulated to obtain a modified polyethylene terephthalate product. The mass ratio of the sodium sulfonate ionomer nucleating agent for polyethylene terephthalate to the polyethylene terephthalate is 1:100-1000.

The working principle and beneficial effects of the present invention are as follows: in this solution, on the one hand, the introduction of sodium sulfonate groups in the nucleating agent can generate ion clusters in the melt of PET, provide crystal nuclei and interfaces for crystallization, accelerate the orderly arrangement of molecular chains (heterogeneous nucleation mechanism), and the flexible molecular chains of the nucleating agent can accelerate the movement of PET molecular chains, indirectly increasing the crystallization rate of PET. On the other hand, the presence of metal salts can make the ionomer maintain a stable structure above the melting point of PET, thereby providing more interfaces for the crystallization of PET. Therefore, the nucleating agent in this solution can increase the melt crystallization temperature of PET and accelerate the crystallization rate. And compared to sodium styrene sulfonate polymers, the molecular chains of the sodium vinyl sulfonate polymers in this solution are more flexible and have a stronger crystallization effect.

Moreover, the use of sulfonate nucleating agents will not cause PET to degrade like hydroxy acid salt nucleating agents, but will significantly reduce the molecular weight, thereby reducing the mechanical properties of PET. In addition, hydroxyethyl methacrylate (HEMA) monomer and glycidyl methacrylate (GMA) monomer are similar to PET molecular structures, and the presence of ester exchange reactions will improve compatibility. Therefore, the introduction of HEMA monomer or GMA monomer can improve the compatibility of the nucleating agent with PET, so that the nucleating agent is evenly dispersed in PET, and the modification effect is significant.

Compared with sodium styrene sulfonate ionomer, the chain of sodium vinyl sulfonate ionomer in this solution is more flexible and has a stronger crystallization effect. On this basis, this solution can also effectively reduce the degradation of PET and improve the mechanical properties of PET, providing a new way for the application of PET as an engineering plastic and expanding the scope of application of PET.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an infrared spectrum of sodium vinyl sulfonate hydroxyethyl methacrylate ionomer obtained in Example 3 of the present invention;

FIG2 is an infrared spectrum of sodium vinyl sulfonate glycidyl methacrylate ionomer obtained in Example 8 of the present invention;

FIG3 is a hydrogen nuclear magnetic spectrum of the sodium vinyl sulfonate hydroxyethyl methacrylate ionomer obtained in Example 3 of the present invention;

FIG4 is a H-NMR spectrum of sodium vinyl sulfonate glycidyl methacrylate ionomer obtained in Example 8 of the present invention;

FIG5 is a hydrogen nuclear magnetic spectrum of sodium p-styrene sulfonate hydroxyethyl methacrylate ionomer obtained in a comparative example of the present invention;

FIG6 is a thermogravimetric analysis graph of PET and PET/VS-HEMA;

FIG7 is a thermogravimetric analysis graph of PET and PET/VS-GMA;

Figure 8 shows the crystallization curves of PET and PET/VS-HEMA during the cooling process of 20°C/min;

Figure 9 shows the crystallization curves of PET and PET/VS-HEMA during the cooling process of 10°C/min;

Figure 10 shows the crystallization curves of PET and PET/VS-GMA during the cooling process of 20°C/min;

Figure 11 shows the crystallization curves of PET and PET/VS-GMA during the cooling process of 10°C/min;

FIG12 is a field emission scanning electron micrograph of PET/VS-HEMA;

FIG13 is a field emission scanning electron micrograph of PET/VS-GMA;

FIG. 14 is a field emission scanning electron micrograph of PET/SSS-HEMA.

DETAILED DESCRIPTION

The following is further described in detail through specific implementation methods:

Example 1

This embodiment provides a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate hydroxyethyl methacrylate ionomer, and the preparation method of the nucleating agent comprises the following steps:

(1) 0.27 g of sodium vinyl sulfonate (VS) monomer, 2.29 mL of hydroxyethyl methacrylate (HEMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel, and after the reaction system was heated to 70°C, it was dripped into the mixed solution at a dripping rate of 5 s/drop, and the reaction was continued for 6 hours (the timing starting point of the reaction time was the time when the initiator began to be dripped, and the other embodiments were the same as the comparative example).

(2) After the reaction is completed, the deionized water and solvent (ethanol) in the reaction system are dried by spin drying to obtain a crude product, which is then dissolved in deionized water and placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium vinyl sulfonate hydroxyethyl methacrylate ionomer (nucleating agent) product.

Example 2

This embodiment provides a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate hydroxyethyl methacrylate ionomer, and the preparation method of the nucleating agent comprises the following steps:

(1) 0.55 g of sodium vinyl sulfonate (VS) monomer, 2.04 mL of hydroxyethyl methacrylate (HEMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel. After the reaction system was heated to 70°C, it was added dropwise to the mixed solution at a dropping rate of 5 s/drop and reacted for 6 hours.

(2) After the reaction is completed, the deionized water and solvent (ethanol) in the reaction system are dried by spin drying to obtain a crude product, which is then dissolved in deionized water and placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium vinyl sulfonate hydroxyethyl methacrylate ionomer (nucleating agent) product.

Example 3

This embodiment provides a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate hydroxyethyl methacrylate ionomer, and the preparation method of the nucleating agent comprises the following steps:

(1) 0.82 g of sodium vinyl sulfonate (VS) monomer, 1.78 mL of hydroxyethyl methacrylate (HEMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel. After the reaction system was heated to 70°C, the mixture was added dropwise at a dropping rate of 5 s/drop and reacted for 6 hours.

(2) After the reaction is completed, the deionized water and solvent (ethanol) in the reaction system are dried by spin drying to obtain a crude product, which is then dissolved in deionized water and placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium vinyl sulfonate hydroxyethyl methacrylate ionomer (nucleating agent) product.

Example 4

This embodiment provides a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate hydroxyethyl methacrylate ionomer, and the preparation method of the nucleating agent comprises the following steps:

(1) 1.09 g of sodium vinyl sulfonate (VS) monomer, 1.53 mL of hydroxyethyl methacrylate (HEMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel. After the reaction system was heated to 70°C, it was added dropwise to the mixed solution at a dropping rate of 5 s/drop and reacted for 6 hours.

(2) After the reaction is completed, the deionized water and solvent (ethanol) in the reaction system are dried by spin drying to obtain a crude product, which is then dissolved in deionized water and placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium vinyl sulfonate hydroxyethyl methacrylate ionomer (nucleating agent) product.

Example 5

This embodiment provides a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate glycidyl methacrylate ionomer, and the preparation method of the nucleating agent comprises the following steps:

(1) 2.46 g of sodium vinyl sulfonate (VS) monomer, 0.28 mL of glycidyl methacrylate (GMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel. After the reaction system was heated to 70°C, it was added dropwise to the mixed solution at a dropping rate of 5 s/drop and reacted for 6 hours.

(2) After the reaction is completed, the deionized water and solvent (ethanol) in the reaction system are dried by spin drying to obtain a crude product, which is then dissolved in deionized water and placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium vinyl sulfonate glycidyl methacrylate ionomer (nucleating agent) product.

Example 6

This embodiment provides a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate glycidyl methacrylate ionomer, and the preparation method of the nucleating agent comprises the following steps:

(1) 2.19 g of sodium vinyl sulfonate (VS) monomer, 0.56 mL of glycidyl methacrylate (GMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel. After the reaction system was heated to 70°C, it was added dropwise to the mixed solution at a dropping rate of 5 s/drop and reacted for 6 hours.

(2) After the reaction is completed, the deionized water and solvent (ethanol) in the reaction system are dried by spin drying to obtain a crude product, which is then dissolved in deionized water and placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium vinyl sulfonate glycidyl methacrylate ionomer (nucleating agent) product.

Example 7

This embodiment provides a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate glycidyl methacrylate ionomer, and the preparation method of the nucleating agent comprises the following steps:

(1) 1.91 g of sodium vinyl sulfonate (VS) monomer, 0.83 mL of glycidyl methacrylate (GMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel. After the reaction system was heated to 70°C, the mixture was added dropwise at a dropping rate of 5 s/drop and reacted for 6 hours.

(2) After the reaction is completed, the deionized water and solvent (ethanol) in the reaction system are dried by spin drying to obtain a crude product, which is then dissolved in deionized water and placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium vinyl sulfonate glycidyl methacrylate ionomer (nucleating agent) product.

Example 8

This embodiment provides a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, wherein the nucleating agent is sodium vinyl sulfonate glycidyl methacrylate ionomer, and the preparation method of the nucleating agent comprises the following steps:

(1) 1.64 g of sodium vinyl sulfonate (VS) monomer, 1.11 mL of glycidyl methacrylate (GMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel. After the reaction system was heated to 70°C, it was added dropwise to the mixed solution at a dropping rate of 5 s/drop and reacted for 6 hours.

(2) After the reaction is completed, the deionized water and solvent (ethanol) in the reaction system are dried by spin drying to obtain a crude product, which is then dissolved in deionized water and placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium vinyl sulfonate glycidyl methacrylate ionomer (nucleating agent) product.

Comparative Example

This comparative example provides a sodium p-styrene sulfonate and hydroxyethyl methacrylate ionomer, and the preparation method of the sodium p-styrene sulfonate and hydroxyethyl methacrylate ionomer is as follows:

(1) 1.73 g of sodium p-styrene sulfonate (SSS) monomer, 1.53 mL of hydroxyethyl methacrylate (HEMA) monomer and ethanol aqueous solution were mixed to obtain a mixed solution; wherein the ethanol aqueous solution was prepared by mixing 18.75 mL of deionized water and 6.25 mL of anhydrous ethanol. 0.048 g of ammonium persulfate, 0.016 g of sodium bisulfite and 15 mL of deionized water were mixed and placed in a constant pressure dropping funnel. After the reaction system was heated to 70°C, the mixture was added dropwise at a dropping rate of 5 s/drop and reacted for 3 hours.

(2) After the reaction is completed, the deionized water and the solvent (ethanol) in the reaction system are dried by rotation to obtain a crude product, which is dissolved in deionized water and then placed in anhydrous ethanol for precipitation, and then dialyzed and vacuum dried to obtain a sodium styrene sulfonate hydroxyethyl methacrylate ionomer product.

The sodium vinyl sulfonate hydroxyethyl methacrylate ionomer was characterized by infrared spectroscopy (FTIR), as shown in Figure 1, in which 3470 cm ^-1 is the stretching vibration peak of OH, 2954 cm ^-1 is the stretching vibration peak of CH, 2362 cm ^-1 is the peak of CO ₂ , which can be ignored, 1647 cm ^-1 is the stretching vibration peak of C=O of the ester group, and 1192-1040 cm ^-1 is the stretching vibration peak of S=O of the sulfonic acid group. The sodium vinyl sulfonate hydroxyethyl methacrylate ionomer can be further characterized by ¹ H-NMR to determine the structure of the ionomer.

The sodium vinyl sulfonate glycidyl methacrylate ionomer was characterized by infrared spectroscopy (FTIR), as shown in Figure 2, in which 2954 cm ^-1 is the stretching vibration peak of CH, 2362 cm ^-1 is the peak of CO ₂ , which can be ignored, 1647 cm ^-1 is the stretching vibration peak of C=O of the ester group, 1192-1040 cm ^-1 is the stretching vibration peak of S=O of the sulfonic acid group, and 910 cm ^-1 is the stretching vibration peak of the epoxy group. The sodium vinyl sulfonate glycidyl methacrylate ionomer can be further characterized by ¹ H-NMR to determine the structure of the ionomer.

FIG3 is a hydrogen nuclear magnetic spectrum of the sodium vinyl sulfonate hydroxyethyl methacrylate ionomer obtained in Example 3. From FIG3 , it can be determined that a random copolymer of the sodium vinyl sulfonate hydroxyethyl methacrylate ionomer is synthesized in Example 3.

FIG4 is a H-NMR spectrum of the sodium vinyl sulfonate glycidyl methacrylate ionomer obtained in Example 8. From FIG4 , the random copolymer of the sodium vinyl sulfonate glycidyl methacrylate ionomer synthesized in Example 8 can be determined.

FIG5 is a hydrogen NMR spectrum of the sodium styrene sulfonate hydroxyethyl methacrylate ionomer obtained in the comparative example. From FIG5 , it can be determined that the random copolymer of the sodium styrene sulfonate hydroxyethyl methacrylate ionomer synthesized in the comparative example is obtained.

The sodium vinyl sulfonate hydroxyethyl methacrylate ionomer product or the sodium vinyl sulfonate glycidyl methacrylate ionomer product obtained in the embodiment is used as a nucleating agent, melt-blended with polyethylene terephthalate, and extruded and granulated to obtain the modified polyethylene terephthalate. The nucleating agent and polyethylene terephthalate are melt-blended at 250-270° C. for 4-7 minutes, and the mass ratio between the nucleating agent and the polyethylene terephthalate is 1:100-1000.

Application Example 1

The nucleating agent (sodium vinyl sulfonate hydroxyethyl methacrylate ionomer obtained in Example 3) and PET were uniformly mixed in a mass ratio of 1:100, and then melt-blended at 250-270° C. and 60 rpm for 5 min, extruded and granulated to obtain modified polyethylene terephthalate, recorded as PET/VS-HEMA.

Application Example 2

The nucleating agent (sodium vinyl sulfonate glycidyl methacrylate ionomer obtained in Example 8) and PET were uniformly mixed in a mass ratio of 1:100, and then melt-blended at 250-270° C. and 60 rpm for 5 min, extruded and granulated to obtain modified polyethylene terephthalate, recorded as PET/VS-GMA.

Application Example 3

The nucleating agent (sodium styrene sulfonate hydroxyethyl methacrylate ionomer obtained in the comparative example) and PET were uniformly mixed in a mass ratio of 1:100, and then melt-blended at 250-270° C. and 60 rpm for 5 min, extruded and granulated to obtain modified polyethylene terephthalate, recorded as PET/SSS-HEMA.

In addition, pure polyethylene terephthalate was also subjected to the same processing conditions as a reference sample, that is, pure polyethylene terephthalate was melt-blended at 250-270° C. and 60 rpm for 5 min and extruded into pellets.

The thermal decomposition temperature of the nucleating agent needs to be above the processing temperature of PET, so the thermal stability of the PET blend with the nucleating agent can be characterized by a thermogravimetric analyzer (TGA), and the results are shown in Figures 6 and 7. As shown in Figures 5 and 6, the TGA curves of pure PET and PET/VS-HEMA and PET/VS-GMA are almost the same, indicating that the nucleating agent in the present invention can maintain a solid state below 400°C without degradation, and can also play a role at the processing temperature of PET, thereby providing nucleation sites for pure PET.

PET, PET/VS-HEMA and PET/VS-GMA were characterized by differential scanning calorimetry (DSC), and the results are shown in Figures 8, 9, 10 and 11. As can be seen from Figures 8 to 11, compared with the PET sample, the modified PET has a significantly increased initial crystallization temperature and a melt crystallization temperature. In addition, the half-peak width of the melt crystallization peak is narrowed. These data can all indicate that vinyl sulfonate ionomer as a nucleating agent can effectively accelerate the crystallization rate of PET.

PET/VS-HEMA, PET/VS-GMA and PET/SSS-HEMA were characterized by field emission scanning electron microscopy (FESEM), and the results are shown in Figures 12, 13 and 14. As can be seen from Figures 12-14, the sodium vinyl sulfonate hydroxyethyl methacrylate ionomer is more uniformly dispersed in the PET matrix, while the sodium vinyl sulfonate glycidyl methacrylate ionomer is more sparsely dispersed. Moreover, the dispersion effect of the sodium vinyl sulfonate hydroxyethyl methacrylate ionomer in the PET matrix is better than that of the sodium styrene sulfonate hydroxyethyl methacrylate ionomer in the PET matrix.

The viscosity of pure PET, PET/VS-HEMA, PET/VS-GMA and PET/SSS-HEMA was tested by Ubbelohde viscometer. The results are shown in Table 1.

Table 1 Viscosity test results

Serial number sample Intrinsic viscosity (dL/g) Viscosity average molecular weight (g/mol) 1 PET 1.103 3.4×10 ⁴ 2 PET/VS-HEMA 1.009 3.2×10 ⁴ 3 PET/VS-GMA 1.072 3.3×10 ⁴ 4 PET/SSS-HEMA 1.065 3.3×10 ⁴

The above test results show that the two nucleating agents (sodium vinyl sulfonate hydroxyethyl methacrylate ionomer and sodium vinyl sulfonate glycidyl methacrylate ionomer) in the present invention can both increase the crystallization temperature of PET, accelerate the crystallization rate of PET, and effectively reduce the degradation of PET (compared to the degree of degradation of PET caused by the hydroxy acid salt nucleating agent), which provides a new way for PET to be used as an engineering plastic and expands the scope of application of PET. In addition, the degree of transesterification between epoxy groups and PET is less than the degree of transesterification between hydroxyl groups and PET, resulting in the dispersibility of sodium vinyl sulfonate glycidyl methacrylate ionomer in PET being inferior to that of sodium vinyl sulfonate hydroxyethyl methacrylate ionomer and sodium p-styrene sulfonate hydroxyethyl methacrylate ionomer, therefore, the modification effect of sodium vinyl sulfonate glycidyl methacrylate ionomer on the crystallization performance of PET is also slightly worse, but the reaction degree is smaller, and the degree of degradation of PET is also smaller, so the intrinsic viscosity and viscosity-average molecular weight of PET/VS-GMA are also higher.

The above are only embodiments of the present invention. The invention is not limited to the fields involved in this implementation case. The common sense such as the known specific structures and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field to which the invention belongs before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the present invention. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to explain the content of the claims.

Claims (10)

1. A sodium sulfonate ionomer nucleating agent for polyethylene terephthalate, characterized by: the nucleating agent is sodium vinyl sulfonate hydroxyethyl methacrylate ionomer or sodium vinyl sulfonate glycidyl methacrylate ionomer, the structure of the sodium vinyl sulfonate hydroxyethyl methacrylate ionomer is shown as a formula (I), and the structure of the sodium vinyl sulfonate glycidyl methacrylate ionomer is shown as a formula (II);

In the formula (I) and the formula (II), m and n are natural numbers, and the value range of m/n is 0.1-9.

2. A process for preparing a sodium sulfonate ionomer nucleating agent for polyethylene terephthalate as defined in claim 1, wherein: the method comprises the following steps:

S1, uniformly mixing a sodium vinylsulfonate monomer, an X monomer and a first solvent to obtain a mixed solution, dissolving an initiator in a second solvent, dropwise adding the solution into the mixed solution, heating to 70-80 ℃, and reacting for 3-6 h; wherein the X monomer is a hydroxyethyl methacrylate monomer or a glycidyl methacrylate monomer;

s2, spin-drying after the reaction is finished to obtain a crude product, dissolving the crude product, placing the crude product into a precipitator for precipitation, purifying and drying to obtain a nucleating agent product.

3. The preparation method according to claim 2, characterized in that: in the step S1, the molar ratio of the sodium vinylsulfonate monomer to the X monomer is 1:0.1-9, and the molar ratio of the sum of the moles of the sodium vinylsulfonate monomer and the X monomer to the mole of the initiator is 100:1-0.1.

4. The preparation method according to claim 2, characterized in that: in the step S1, the first solvent is ethanol water solution, and the volume ratio of absolute ethanol to water in the ethanol water solution is 1-10:3; the second solvent is deionized water.

5. The preparation method according to claim 2, characterized in that: in step S1, the initiator is a sulfate-bisulfite.

6. The preparation method according to claim 2, characterized in that: in step S2, the precipitant is absolute ethanol.

7. The preparation method according to claim 2, characterized in that: in step S1, the initiator is added to the mixed solution at a dropping speed of 4 to 8S/drop after being dissolved in the second solvent.

8. Use of the sodium sulfonate ionomer nucleating agent for polyethylene terephthalate as claimed in claim 1 for modifying polyethylene terephthalate.

9. The use according to claim 8, characterized in that: uniformly mixing the sodium sulfonate ionomer nucleating agent for polyethylene terephthalate according to claim 1 with the polyethylene terephthalate, melt-blending for 4-7 min at 250-270 ℃, extruding and granulating to obtain a modified polyethylene terephthalate product.

10. The use according to claim 9, characterized in that: the mass ratio of the sodium sulfonate ionomer nucleating agent for the polyethylene terephthalate to the polyethylene terephthalate is 1:100-1000.