A spinning-grade fully aromatic polynaphthyl ester resin and its preparation method

Abstract

The present invention belongs to the technical field of polymer materials, and particularly relates to a spinning-grade fully aromatic polynaphthyl ester resin and a preparation method thereof. The present invention utilizes p-hydroxybenzoic acid, 6-hydroxy-2-naphthylcarboxylic acid, aromatic dicarboxylic acid, and ethylene glycol monomers as raw materials, and conducts a polymerization reaction under the action of a catalyst. The spinning-grade fully aromatic polynaphthyl ester resin is successfully obtained under specific reaction conditions. The resin has a high molecular weight, low impurity content, good heat resistance, good melt fluidity, and exhibits more pronounced shear thinning, and can be directly used in the preparation of polynaphthyl ester fibers.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a spinning-grade fully aromatic polynaphthyl ester resin and a preparation method thereof. Background Art

[0002] As a high-performance polymer material with a naphthalene ring backbone, polynaphthalene ester (PBES) exhibits significantly increased main chain rigidity due to the naphthalene ring structure within the molecular chain, resulting in excellent mechanical, thermal, barrier, and radiation resistance properties. PBES can be processed into fibers, films, and sheets for use in high-end applications such as aerospace and atomic energy materials. PBES fibers, due to their strong mechanical and thermal properties and excellent stability, are used in high-end applications such as high-speed tires, ropes, and special protective equipment. However, the increased rigidity of the PBES chain leads to a series of problems, including increased glass transition temperature, high crystallization temperature, and poor melt fluidity, ultimately making PBES spinning difficult. Developing spinning-grade PBES resins and improving the spinning process are the primary approaches to addressing this issue, with spinning-grade PBES resins being the key.

[0003] At present, the preparation routes of polynaphthyl ester resin include direct esterification and transesterification. The direct esterification method is similar to the reaction of PET, but due to the presence of naphthalene rings, the steric hindrance effect is increased, so the reaction conditions are extremely harsh and the purity of the monomer is high, and there are no industrialized products at present. The transesterification method is the most widely used method in industry. The process is divided into two parts. The first is melt transesterification. In this stage, the molecular weight is high, resulting in high melt viscosity, mass transfer and heat transfer problems, which easily cause uneven molecular weight distribution, and even carbonization increases impurities and poor batch stability. The second is solid phase polycondensation, which further increases the molecular weight of polynaphthyl ester. However, the increase in molecular weight requires higher temperature and high vacuum conditions, which has higher requirements on equipment, and the reaction time is long, up to dozens of hours. The disadvantage of long cycle is self-evident.

[0004] As we all know, polymer fibers are produced by melting, forming, and winding polymer resins. Therefore, stable fiber formation requires polymer resins with excellent fluidity, a high molecular weight with a narrow molecular weight distribution, and low impurity content. Clearly, polynaphthyl esters currently produced using traditional methods are insufficient for the production of polynaphthyl ester fibers. Therefore, the development of spinning-grade fully aromatic polynaphthyl ester resins is essential. Summary of the Invention

[0005] In order to solve the above problems, the present invention considers replacing the fat part with a fully aromatic group in the molecular structure, thereby increasing the rigidity of the molecular chain segments and reducing the entanglement between the molecular segments to greatly increase the fluidity and facilitate spinning.

[0006] Specifically, in one aspect, the present invention provides a method for preparing a spinning-grade wholly aromatic polynaphthyl ester resin, the preparation method comprising: using p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, aromatic dicarboxylic acid and ethylene glycol monomers as raw materials, and carrying out a polymerization reaction under the action of a catalyst to obtain a spinning-grade wholly aromatic polynaphthyl ester resin.

[0007] Furthermore, the polymerization reaction includes: first reacting at 210-240°C for 1.5-3h, then raising the temperature to 315-325°C at a rate of ≤3°C / min, reacting under vacuum for 0.5-3h, and then reacting under nitrogen for 1-3h, crushing and drying the reaction product to obtain a wholly aromatic polynaphthyl ester prepolymer, and finally reacting and extruding the prepolymer at 300-340°C and a vacuum degree of ≥0.07MPa for 5-20min, pelletizing, and drying to obtain a spinning-grade wholly aromatic polynaphthyl ester resin.

[0008] Furthermore, the preparation method further includes acetyling the p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid before the polymerization reaction, and the ethylene glycol monomer is ethylene glycol and the ethylene glycol is acetylated before the polymerization reaction, or the ethylene glycol monomer is ethylene glycol diacetate.

[0009] Furthermore, the acetylation of p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid or ethylene glycol is achieved by using acetic anhydride at 135-155° C. for 3-5 h.

[0010] Furthermore, in the raw materials, according to molar percentage, the content of p-hydroxybenzoic acid is 60%-80%, the content of 6-hydroxy-2-naphthoic acid is 20%-32%, the content of aromatic dicarboxylic acid is 1%-6%, and the content of ethylene glycol monomer is 1%-6%.

[0011] Furthermore, the aromatic dicarboxylic acid is HOOC-Ar-COOH, wherein Ar is selected from

[0012] Furthermore, the catalyst is selected from sulfuric acid, trifluoromethanesulfonic acid, methyl trifluoromethanesulfonate, titanium dioxide, titanium glycol, titanium acetylacetonate, n-butyl titanate, isopropyl titanate, antimony glycol, antimony trioxide, antimony acetate, stannous octoate, stannous oxalate, dibutyltin oxide, dibutyltin dilaurate, butylstannoic acid, lithium acetate, potassium acetate, calcium acetate, magnesium acetate, barium acetate, zinc acetate, cobalt acetate, antimony acetate, lead acetate, manganese acetate, triisopropoxyaluminum, zinc acetate, zinc oxide, stannous chloride, concentrated sulfuric acid, p-toluenesulfonic acid, magnesium acetate, zinc acetate, zinc chloride, lithium chloride, germanium chloride, tin tetrachloride, potassium carbonate, triethylenediamine, triethylamine, zinc lactate, or a mixture of any proportions of any of the following:

[0013] Furthermore, the added amount of the catalyst is 1-1.5 wt% of the total weight of all reaction monomers.

[0014] Furthermore, the catalyst may be a mixture of magnesium acetate and n-butyl titanate. Furthermore, the mass ratio of magnesium acetate to n-butyl titanate in the mixture is 1:1 to 3:1.

[0015] In other aspects, the present invention provides a spinning-grade fully aromatic polynaphthyl ester resin obtained by the preparation method described herein.

[0016] In other aspects, the present invention provides use of the spinning-grade fully aromatic polynaphthyl ester resin as described herein or obtained by the preparation method described herein in preparing polynaphthyl ester fibers.

[0017] Beneficial effects of the present invention

[0018] The present invention uses p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, aromatic dicarboxylic acid and ethylene glycol monomers as raw materials, performs a polymerization reaction under the action of a catalyst, and successfully obtains a spinning-grade fully aromatic polynaphthyl ester resin under specific reaction conditions. The fully aromatic polynaphthyl ester resin has a high molecular weight, a low impurity content, good heat resistance, good melt fluidity and exhibits a more obvious shear thinning phenomenon, and can be directly used for the preparation of polynaphthyl ester fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure shows the product obtained after spinning of the spinning-grade wholly aromatic polynaphthyl ester resin prepared in the embodiment of the present invention.

[0020] Figure 2 The picture shows the product obtained after spinning of the wholly aromatic polynaphthyl ester resin prepared in the comparative example of the present invention. DETAILED DESCRIPTION

[0021] The present invention uses p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, aromatic dicarboxylic acid and ethylene glycol monomers as raw materials, and carries out a polymerization reaction under the action of a catalyst to obtain a spinning-grade fully aromatic polynaphthyl ester resin. The reaction scheme is as follows:

[0022]

[0023] The present invention is further described below with reference to specific examples, which, however, are not intended to limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0024] Example 1

[0025] This embodiment provides a spinning-grade fully aromatic polynaphthyl ester resin, which is prepared as follows:

[0026] (1) Acetylation of p-hydroxybenzoic acid: 10 mol (1380 g) of p-hydroxybenzoic acid and 15 mol (1531.4 g) of acetic anhydride were weighed and added to a 5 L reactor equipped with a stirrer, a thermometer, and a reflux condenser. The mixture was refluxed at 140° C. for 3 h to obtain a p-acetoxybenzoic acid solution. The solution was poured into cold water, washed with water, filtered for more than 3 times, and dried at 200° C. for 2 h (2-4 h) to obtain purified p-acetoxybenzoic acid with a purity of 98.8% (≥97.8%) and a yield of 96%.

[0027] (2) Acetylation of 6-hydroxy-2-naphthoic acid: 10 mol (1881.8 g) of 6-hydroxy-2-naphthoic acid and 15 mol (1531.4 g) of acetic anhydride were weighed and added to a 5 L reactor equipped with a stirrer, a thermometer, and a reflux condenser. The mixture was refluxed at 140° C. (135-155° C.) for 3 h (3-5 h) to obtain a 6-acetoxy-2-naphthoic acid solution. The solution was poured into cold water, washed with water, filtered for more than 3 times, and dried at 200° C. for 2 h to obtain purified 6-acetoxy-2-naphthoic acid with a purity of 98.5% (≥97.8%) and a yield of 95%.

[0028] (3) Preparation of spinning-grade fully aromatic polynaphthyl ester resin: 3.25 mol (585.5 g) of purified p-acetoxybenzoic acid, 1.25 mol (284.78 g) of purified 6-acetoxy-2-naphthoic acid, 0.25 mol (36.54 g) of ethylene glycol diacetate (1%-6%), 0.25 mol (54.05 g) of 2,6-naphthalene dicarboxylic acid and 1 wt% of the total weight of the monomers as catalysts (the mass ratio of magnesium acetate to n-butyl titanate is 7:3) were weighed and added to a 5 L belt. In a reaction kettle equipped with mechanical stirring, a reflux condenser and vacuum, the temperature is raised to 220°C for reaction for 2 hours, then the temperature is raised to 320°C at a rate of 0.5°C / min, the reaction is carried out under vacuum for 0.5 hours, nitrogen is then introduced into the reaction kettle, the reaction is carried out for 1 hour, the temperature is lowered and the material is discharged, and the whole aromatic polynaphthyl ester resin prepolymer is obtained by crushing and drying. The above prepolymer is added to a continuous polymerization device, reacted and extruded at a temperature of 320°C and a vacuum degree of 0.08 MPa for 10 minutes, pelletized and dried to obtain a spinning-grade high molecular weight whole aromatic polynaphthyl ester resin with a yield of about 80%.

[0029] Testing of the resulting spinning-grade fully aromatic polynaphthyl ester resin revealed the following results: The intrinsic viscosity of the prepared fully aromatic polynaphthyl ester resin, measured at 60°C in a 0.1 g / dL solution of pentafluorophenol, was 6.9 (range 5.6-8.7) using an Ubbelohde viscometer, indicating a high molecular weight. Ash content measured in a high-temperature muffle furnace was less than 0.05% (≤0.14%), indicating low impurity content. Thermal properties measured by DCS and TGA revealed a melting point of 280°C, a thermal decomposition temperature of 500°C, and a carbon residue of 39.23% at 800°C, demonstrating excellent heat resistance. A plate rheometer measured the resin's viscosity at 300°C and 1 Hz to be 300 Pa.s (range 250-430 Pa.s), with significant shear thinning, indicating excellent flowability. The prepared fully aromatic polynaphthyl ester resin can be directly used in fiber production.

[0030] Figure 1 3 is a picture of the product obtained after spinning the spinning-grade wholly aromatic polynaphthyl ester resin prepared in this example, indicating that the polynaphthyl ester fiber was successfully prepared.

[0031] Comparative Example 1

[0032] This comparative example provides a wholly aromatic polynaphthyl ester resin, which is prepared as follows:

[0033] (1) Acetylation of p-hydroxybenzoic acid: 10 mol (1380 g) of p-hydroxybenzoic acid and 15 mol (1531.4 g) of acetic anhydride were weighed and added to a 5 L reactor equipped with a stirrer, a thermometer, and a reflux condenser. The mixture was refluxed at 133° C. for 3 h to obtain a p-acetoxybenzoic acid solution. The solution was poured into cold water, washed with water, filtered for more than 3 times, and dried at 200° C. for 2 h to obtain purified p-acetoxybenzoic acid with a purity of 97.5% and a yield of 92%.

[0034] (2) Acetylation of 6-hydroxy-2-naphthoic acid: 10 mol (1881.8 g) of 6-hydroxy-2-naphthoic acid and 15 mol (1531.4 g) of acetic anhydride were weighed and added to a 5 L reactor equipped with a stirrer, a thermometer, and a reflux condenser. The mixture was refluxed at 135° C. for 3 h to obtain a 6-acetoxy-2-naphthoic acid solution. The solution was poured into cold water, washed with water, filtered for more than 3 times, and dried at 200° C. for 2 h to obtain purified 6-acetoxy-2-naphthoic acid with a purity of 96.8% and a yield of 95%.

[0035] (3) Preparation of fully aromatic polynaphthyl ester resin: 3.25 mol (585.5 g) of purified p-acetoxybenzoic acid, 1.25 mol (284.78 g) of purified 6-acetoxy-2-naphthoic acid, 0.6 mol (87.696 g) of ethylene glycol diacetate, 0.6 mol (129.72 g) of 2,6-naphthalene dicarboxylic acid, and 1.2 wt% of the total weight of the monomers as catalysts of magnesium acetate and n-butyl titanate (the mass ratio of magnesium acetate to n-butyl titanate is 7:3) were weighed and added to 5 L of ethanol. In a reaction kettle equipped with mechanical stirring, a reflux condenser and vacuum ability, the temperature is raised to 230°C for reaction for 2 hours, then the temperature is raised to 320°C at a rate of 5°C / min and the reaction is carried out under vacuum for 1 hour, nitrogen is then introduced into the reaction kettle, the reaction is carried out for 1 hour, the temperature is lowered and the material is discharged, and the whole aromatic polynaphthyl ester resin is obtained by crushing and drying. The above prepolymer is added to a continuous polymerization device, reacted and extruded at a temperature of 315°C and a vacuum degree of 0.05 MPa for 10 minutes, pelletized and dried to obtain a high molecular weight whole aromatic polynaphthyl ester resin with a yield of about 78%.

[0036] The resulting high-molecular-weight wholly aromatic polynaphthyl ester resin was tested. The results were as follows: A 0.1 g / dL solution prepared with pentafluorophenol exhibited an intrinsic viscosity of 3.9 at 60°C using an Ubbelohde viscometer. Ash content was measured in a high-temperature muffle furnace to be 1.5%, indicating a high impurity content. Thermal properties, measured by DCS and TGA, revealed a melting point of 265°C, a thermal decomposition temperature of 489°C, and a carbon residue of 37.37% at 800°C, demonstrating excellent heat resistance. A plate rheometer measured the resin's viscosity at 300°C and 1 Hz to be 516 Pa.s. The prepared wholly aromatic polynaphthyl ester resin cannot be directly used for fiber production. These results indicate that spinning-grade polynaphthyl ester cannot be produced directly using the same raw materials under different reaction conditions.

[0037] Figure 2 This is a picture of the product obtained after spinning the wholly aromatic polynaphthyl ester resin prepared in this comparative example, indicating that polynaphthyl ester fiber could not be successfully obtained.

[0038] It should be noted that the preferred embodiments of the present invention are given in the description of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this description. These embodiments are not intended to be additional limitations on the content of the present invention. The purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. In addition, the above-mentioned technical features are further combined with each other to form various embodiments not listed above, which are all considered to be within the scope of the description of the present invention. Furthermore, it is obvious to those skilled in the art that improvements or changes can be made based on the above description, and all such improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a spinning-grade fully aromatic polynaphthyl ester resin, characterized in that: The preparation method comprises the following steps: (1) Acetylation of p-hydroxybenzoic acid: Weigh p-hydroxybenzoic acid and acetic anhydride and add them to a reactor equipped with a stirrer, a thermometer, and a reflux condenser. React at a temperature of 135-155°C for 3-5 hours to obtain a p-acetoxybenzoic acid solution. Pour the obtained solution into cold water, wash with water, filter for more than 3 times, and dry to obtain purified p-acetoxybenzoic acid. (2) Acetylation of 6-hydroxy-2-naphthoic acid: Weigh 6-hydroxy-2-naphthoic acid and acetic anhydride and add them to a reactor equipped with a stirrer, a thermometer, and a reflux condenser. Reflux at 135-155°C for 3-5 hours to obtain a 6-acetoxy-2-naphthoic acid solution. Pour the solution into cold water, wash with water, filter for more than 3 times, and dry to obtain purified 6-acetoxy-2-naphthoic acid. (3) Preparation of spinning-grade fully aromatic polynaphthyl ester resin: Weigh purified 4-acetoxybenzoic acid, purified 6-acetoxy-2-naphthoic acid, ethylene glycol diacetate, 2,6-naphthalene dicarboxylic acid and catalyst into a reactor, raise the temperature to 210-240°C and react for 1.5-3h, then raise the temperature to 315-325°C at a rate of 0.5°C / min and react under vacuum for 0.5-3h, then fill the reactor with nitrogen and react for 1-3h, cool and discharge the material, and crush and dry to obtain fully aromatic polynaphthyl ester. Resin prepolymer; the obtained prepolymer is reactively extruded at a temperature of 300-340° C. and a vacuum degree of ≥0.07 MPa for 5-20 minutes, pelletized, and dried to obtain a spinning-grade wholly aromatic polynaphthyl ester resin; wherein, in the raw materials, the content of p-hydroxybenzoic acid is 60%-80%, the content of 6-hydroxy-2-naphthoic acid is 20%-32%, the content of 2,6-naphthalenedicarboxylic acid is 1%-6%, the content of ethylene glycol diacetate is 1%-6%, and the total molar ratio of the raw materials is 100%.

2. The preparation method according to claim 1, characterized in that The catalyst is selected from sulfuric acid, trifluoromethanesulfonic acid, methyl trifluoromethanesulfonate, titanium dioxide, titanium glycol, titanium acetylacetonate, n-butyl titanate, isopropyl titanate, antimony glycol, antimony trioxide, antimony acetate, stannous octoate, stannous oxalate, dibutyltin oxide, dibutyltin dilaurate, butylstannoic acid, lithium acetate, potassium acetate, calcium acetate, magnesium acetate, barium acetate, zinc acetate, cobalt acetate, antimony acetate, lead acetate, manganese acetate, triisopropoxyaluminum, zinc acetate, zinc oxide, stannous chloride, concentrated sulfuric acid, p-toluenesulfonic acid, magnesium acetate, zinc acetate, zinc chloride, lithium chloride, germanium chloride, tin tetrachloride, potassium carbonate, triethylenediamine, triethylamine, zinc lactate, or a mixture of any proportions of any of the following.

3. The preparation method according to claim 1, characterized in that The amount of the catalyst added is 1-1.5 wt% of the total weight of all the reaction monomers.

4. The preparation method according to claim 2, characterized in that The catalyst is a mixture of magnesium acetate and n-butyl titanate.

5. The preparation method according to claim 4, characterized in that The mass ratio of magnesium acetate to n-butyl titanate in the mixture is 1:1 to 3:

1.

6. A spinning-grade wholly aromatic polynaphthyl ester resin obtained by the preparation method according to any one of claims 1 to 5.

7. Use of the spinning-grade wholly aromatic polynaphthyl ester resin according to claim 6 in the preparation of polynaphthyl ester fibers.

Images