Spinning-grade wholly aromatic polynaphthoate resin and preparation method therefor

Abstract

The present invention relates to the technical field of polymer materials, and in particular to a spinning-grade wholly aromatic polynaphthoate resin and a preparation method therefor. In the present invention, p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, an aromatic dicarboxylic acid, and an ethylene glycol monomer are used as starting materials and are polymerized under the action of a catalyst. Under specific reaction conditions, a spinning-grade wholly aromatic polynaphthoate resin is successfully obtained. The spinning-grade wholly aromatic polynaphthoate resin has high molecular weight, low impurity content, good heat resistance and good melt fluidity, exhibits a more pronounced shear thinning behavior, and can be directly used for the preparation of polynaphthoate fibers.

Description

A spinning-grade all-aryl polynaphthalene ester resin and its preparation method Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a spinning-grade all-aryl polynaphthalene ester resin and its preparation method. Background Technology

[0002] Polynatrimethylene ester (PAN), a high-performance polymer material with a naphthalene ring backbone, exhibits significantly increased main-chain rigidity due to the naphthalene ring structure, resulting in excellent mechanical, thermal, barrier, and radiation resistance properties. PAN can be processed into fibers, films, and sheets for high-end applications such as aerospace and nuclear materials. PAN fibers, in particular, are suitable for high-speed tires, ropes, and special protective applications due to their strong mechanical, thermal, and excellent stability. However, the increased rigidity of the PAN chain leads to a series of problems, including higher glass transition temperature, higher crystallization temperature, and poor melt flowability, ultimately making PAN spinning difficult. Developing spinning-grade PAN resins and improving the spinning process are the main approaches to solving this problem, with spinning-grade PAN resins being fundamental.

[0003] Currently, there are two main routes for preparing polynatride resin: direct esterification and transesterification. Direct esterification is similar to the reaction in PET, but the presence of the naphthalene ring increases steric hindrance, resulting in extremely demanding reaction conditions and high monomer purity requirements; no industrially produced products have been found yet. Transesterification is currently the most widely used method in industry. This process consists of two parts: first, melt transesterification. In the later stages of this stage, the high molecular weight leads to high melt viscosity, causing mass and heat transfer problems, easily resulting in uneven molecular weight distribution, and even carbonization increasing impurities and poor batch stability. The second step is solid-state polycondensation, which further increases the molecular weight of polynatride. However, increasing the molecular weight requires high temperatures and high vacuum conditions, placing high demands on equipment and resulting in a long reaction time, sometimes reaching tens of hours; the long cycle is a significant drawback.

[0004] As is well known, polymer fibers are obtained by melting, fiberizing, and winding polymer resins. Therefore, stable fiber forming requires polymer resins with excellent flowability, high molecular weight with narrow distribution, and low impurity content. Clearly, polynatride prepared using traditional methods cannot meet the requirements for polynatride fiber production. Therefore, developing spinning-grade all-aryl polynatride resins is necessary. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes to replace the fatty portion with fully aromatic groups in the molecular structure, thereby increasing the rigidity of the molecular chain segments and reducing entanglement between them to significantly increase fluidity and facilitate spinning.

[0006] Specifically, in one aspect, the present invention provides a method for preparing a spinning-grade all-aryl polynaphthalene ester resin, the 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 all-aryl polynaphthalene ester resin.

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

[0008] Furthermore, the preparation method further includes acetylation of 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 reacting acetic anhydride at 135-155°C for 3-5 hours.

[0010] Furthermore, in the raw materials, the content of p-hydroxybenzoic acid is 60%-80% by molar percentage, 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] Further, the catalyst is selected from sulfuric acid, trifluoromethanesulfonic acid, methyl trifluoromethanesulfonate, titanium dioxide, titanium glycol, titanium acetylacetonate, n-butyl titanate, isopropyl titanate, antimony glycolate, antimony trioxide, antimony acetate, stannous octoate, stannous oxalate, dibutyltin oxide, dibutyltin dilaurate, butylstannic acid, lithium acetate, potassium acetate, calcium acetate, magnesium acetate, barium acetate, zinc acetate, cobalt acetate, antimony acetate, lead acetate, manganese acetate, aluminum triisopropoxy, zinc acetate, zinc oxide, stannous chloride, concentrated sulfuric acid, p-toluenesulfonic acid, magnesium acetate, zinc acetate, zinc chloride, lithium chloride, germanium chloride, stannous tetrachloride, potassium carbonate, triethylenediamine, triethylamine, and zinc lactate, or a mixture of several of these in any proportion.

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

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

[0015] In other respects, the present invention provides a spinning-grade all-aryl polynaphthalene ester resin obtained by the preparation method described herein.

[0016] In other respects, the present invention provides the use of spinning-grade all-aryl polynaphthalene ester resins as described herein or prepared by the methods described herein in the preparation of polynaphthalene ester fibers.

[0017] Beneficial effects of the present invention

[0018] This invention uses p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, aromatic dicarboxylic acid and ethylene glycol monomers as raw materials to carry out a polymerization reaction under the action of a catalyst, and successfully obtains a spinning-grade all-aryl polynaphthyl ester resin under specific reaction conditions. It has a high molecular weight, low impurity content, good heat resistance, good melt flowability and more obvious shear thinning phenomenon, and can be directly used for the preparation of polynaphthyl ester fibers. Attached Figure Description

[0019] Figure 1 shows an image of the product obtained after spinning of the spinning-grade all-aryl polynaphthalene ester resin prepared according to an embodiment of the present invention.

[0020] Figure 2 shows an image of the product obtained after spinning of the all-aryl polynaphthalene ester resin prepared in the comparative example of this section. Detailed Implementation

[0021] This 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 all-aryl polynaphthalene ester resin. The reaction route is shown below:

[0022] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not 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 this technical field.

[0023] Example 1

[0024] This embodiment provides a spinning-grade all-aryl polynaphthalene ester resin, which is prepared as follows:

[0025] (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, thermometer and 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 and filtered 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%.

[0026] (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, thermometer and 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 and filtered 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%.

[0027] (3) Preparation of spinning-grade all-aryl polynaphthalene ester resin: Weigh 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-naphthalenedicarboxylic acid, and 1 wt% of magnesium acetate and n-butyl titanate as catalysts (mass ratio of magnesium acetate to n-butyl titanate is 7:3) and add them to a 5L container. In a reaction vessel equipped with mechanical stirring, a reflux condenser, and a vacuum system, the temperature was raised to 220°C and reacted for 2 hours. Then, the temperature was raised to 320°C at a rate of 0.5°C / min and reacted under vacuum for 0.5 hours. Nitrogen gas was then introduced into the reaction vessel, and the reaction was continued for 1 hour. The mixture was then cooled and discharged, pulverized, and dried to obtain a fully aromatic polynaphthalene resin prepolymer. The prepolymer was then added to a continuous polymerization apparatus and reacted and extruded at 320°C and a vacuum of 0.08 MPa for 10 minutes. After pelleting and drying, a high molecular weight fully aromatic polynaphthalene resin of spinning grade was obtained, with a yield of approximately 80%.

[0028] The obtained spinning-grade all-aryl polynaphthalene ester resin was tested, and the results are as follows: A 0.1 g / dL solution prepared with pentafluorophenol showed an intrinsic viscosity of 6.9 (5.6-8.7) at 60℃ using an Ubbelohde viscometer, indicating a relatively high molecular weight. The 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 showed a melting point of 280℃, a thermal decomposition temperature of 500℃, and a char residue of 39.23% at 800℃, demonstrating good heat resistance. A plate rheometer test showed a viscosity of 300 Pa·s (250-430 Pa·s) at 300℃ and 1 Hz, exhibiting more pronounced shear thinning, indicating excellent flowability. The prepared all-aryl polynaphthalene ester resin can be directly used for fiber preparation.

[0029] Figure 1 is a picture of the product obtained after spinning of the spinning-grade all-aryl polynaphthalene ester resin prepared in this embodiment, indicating that polynaphthalene ester fiber was successfully prepared.

[0030] Comparative Example 1

[0031] This comparative example provides a fully aromatic polynaphthalene ester resin, which is prepared as follows:

[0032] (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, thermometer and 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 and filtered 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%.

[0033] (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, thermometer and 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 and filtered 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%.

[0034] (3) Preparation of all-aryl polynaphthalene ester resin: Weigh 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-naphthalenedicarboxylic acid, and 1.2 wt% of magnesium acetate and n-butyl titanate as catalysts (mass ratio of magnesium acetate to n-butyl titanate is 7:3) and add them to 5 L In a reactor equipped with mechanical stirring, a reflux condenser, and a vacuum system, the temperature was raised to 230°C and reacted for 2 hours. Then, the temperature was raised to 320°C at a rate of 5°C / min and reacted under vacuum for 1 hour. Nitrogen gas was then introduced into the reactor, and the reaction was continued for 1 hour. The mixture was then cooled and discharged, pulverized, and dried to obtain a fully aromatic polynaphthalene resin. The prepolymer was then added to a continuous polymerization apparatus and reacted and extruded at 315°C and a vacuum of 0.05 MPa for 10 minutes. After pelleting and drying, a high molecular weight fully aromatic polynaphthalene resin was obtained, with a yield of approximately 78%.

[0035] The obtained high molecular weight fully aromatic polynaphthalene ester resin was tested, and the results are as follows: A 0.1 g / dL solution prepared with pentafluorophenol showed an intrinsic viscosity of 3.9 at 60°C, measured using an Ubbelohde viscometer; the ash content in a high-temperature muffle furnace was 1.5%, indicating a high impurity content; thermal properties measured by DCS and TGA showed a melting point of 265°C, a thermal decomposition temperature of 489°C, and a char residue of 37.37% at 800°C, exhibiting good heat resistance; its viscosity at 300°C and 1 Hz, measured by a plate rheometer, was 516 Pa·s. The prepared fully aromatic polynaphthalene ester resin cannot be directly used for fiber preparation. These results indicate that even using the same raw materials, spinning-grade polynaphthalene ester cannot be obtained under different reaction conditions.

[0036] Figure 2 is a picture of the product obtained after spinning of the all-aryl polynaphthalene ester resin prepared in this comparative example, indicating that polynaphthalene ester fibers could not be successfully obtained.

[0037] It should be noted that while the preferred embodiments of the present invention are provided in this specification, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of the present invention; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of the present invention. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a spinning-grade all-aryl polynaphthalene ester resin, characterized in that, The preparation method includes: using p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, aromatic dicarboxylic acid, and ethylene glycol monomers as raw materials, carrying out a polymerization reaction under the action of a catalyst to obtain a spinning-grade all-aryl polynaphthalene ester resin. The polymerization reaction includes: first, reacting at 210-240℃ for 1.5-3h; then, raising the temperature to 315-325℃ at a rate of ≤3℃ / min; reacting under vacuum for 0.5-3h; then, reacting under nitrogen for 1-3h; pulverizing and drying the reaction product to obtain a fully aromatic polynaphthalene ester prepolymer; and finally, reacting and extruding the prepolymer at 300-340℃ and a vacuum of ≥0.07MPa for 5-20min, pelletizing, and drying to obtain spinning-grade fully aromatic polynaphthalene ester resin.

2. The preparation method according to claim 1, characterized in that, The preparation method further includes acetylation of 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.

3. The preparation method according to claim 2, characterized in that, The acetylation of p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, or ethylene glycol is achieved by reacting acetic anhydride at 135-155°C for 3-5 hours.

4. The preparation method according to claim 1, characterized in that, In the raw materials, the content of p-hydroxybenzoic acid is 60%-80% by molar percentage, 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%.

5. The preparation method according to claim 1, characterized in that, The aromatic dicarboxylic acid is HOOC-Ar-COOH, wherein Ar is selected from...

6. 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 glycolate, antimony trioxide, antimony acetate, stannous octoate, stannous oxalate, dibutyltin oxide, dibutyltin dilaurate, butylstannic acid, lithium acetate, potassium acetate, calcium acetate, magnesium acetate, barium acetate, zinc acetate, cobalt acetate, antimony acetate, lead acetate, manganese acetate, aluminum triisopropoxy, zinc acetate, zinc oxide, stannous chloride, concentrated sulfuric acid, p-toluenesulfonic acid, magnesium acetate, zinc acetate, zinc chloride, lithium chloride, germanium chloride, stannous tetrachloride, potassium carbonate, triethylenediamine, triethylamine, and zinc lactate, or a mixture of several of these in any proportion.

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

8. The preparation method according to claim 6, characterized in that, The catalyst is a mixture of magnesium acetate and n-butyl titanate; Furthermore, the mass ratio of magnesium acetate to tetrabutyl titanate in the mixture is 1:1 to 3:

1.

9. A spinning-grade all-aryl polynaphthalene ester resin obtained by the preparation method according to any one of claims 1-8.

10. The application of the spinning-grade all-aryl polynaphthalene ester resin as described in claim 9 in the preparation of polynaphthalene ester fibers.

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