A retort-resistant, low-yellowing-finger polyamide, its preparation method and application

Abstract

This invention belongs to the field of polyamide products, and discloses a retort-resistant, low-yellowing-index polyamide, its preparation method, and its applications. The polyamide is polymerized from the following components: X is an alicyclic diamine 3,3'-dimethyl-4,4-diaminodicyclohexylmethane or a derivative thereof with substituents on its cyclohexyl group; Y is bis(4-aminophenoxy)benzene or a derivative thereof with substituents on its benzene ring; and Z is an aliphatic diacid. The polyamide PA XZ / YZ and its composition obtained by this invention, compared to traditional long-chain nylons, alicyclic nylons such as TR90, have a higher glass transition temperature, thus exhibiting higher temperature resistance and retort resistance. Simultaneously, it maintains low water absorption, high toughness, and a lighter color.

Description

Technical Field

[0001] This invention belongs to the field of polyamide products, and specifically relates to a retortable, low-yellowing-index polyamide, its preparation method, and its application. Background Technology

[0002] Polyamide (hereinafter referred to as PA) has excellent mechanical, high temperature resistance, wear resistance, oil resistance and processing properties. It has become an indispensable means of production in human society and is widely used in industries such as electronics, automobiles, construction, office equipment, machinery, and aerospace, playing a very important role in the national economy.

[0003] PA66 and PA6 are the most produced varieties in the PA family, with suitable production costs and meeting the needs of common applications. However, they also have drawbacks such as poor salt tolerance, high water absorption, poor hydrolysis resistance, and insufficient heat resistance. Later, researchers developed long-chain PAs and alicyclic PAs to overcome these shortcomings. Long-chain PA molecules have a methylene to amide bond ratio of at least 7 in the main chain. In addition to possessing most of the general properties of PAs, such as lubricity, wear resistance, pressure resistance, and processability, long-chain PAs also exhibit good toughness and flexibility, low water absorption, good dimensional stability, good salt and hydrolysis resistance, and low density. Alicyclic PAs have high glass transition temperatures, providing better heat resistance, while also reducing crystallization, improving transparency, and expanding their application range. Among them, TR90 developed by EMS is the most famous. This material uses alicyclic diamines and long-chain diacids as its main components, successfully achieving high heat resistance, low water absorption, high transparency, and high toughness.

[0004] Due to the excellent properties of this type of polymer, its market applications are gradually expanding. However, in the development of new applications, it has been found that commercially available materials such as TR90 still suffer from insufficient heat resistance in some new applications, particularly in the medical and food sectors where steam sterilization is required. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a retortable, low-yellowing polyamide. This polyamide has a diamine structure of bis(4-aminophenoxy)benzene or its derivatives, exhibits a higher glass transition temperature than the MACM of TR90, and maintains toughness, low water absorption, and a lighter color.

[0006] Another objective of this invention is to provide a method for preparing the above-mentioned retort-resistant, low-yellowing-index polyamide.

[0007] Another object of the present invention is to provide the application of the above-mentioned retort-resistant, low-yellowing-index polyamide.

[0008] The objective of this invention is achieved through the following solution: A polyamide PA XZ / YZ is polymerized from the following components: X is an alicyclic diamine 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM) or a derivative thereof with a substituent on the cyclohexyl group; Y is bis(4-aminophenoxy)benzene or a derivative thereof with substituents on its benzene ring; Z is an aliphatic diacid; The alicyclic diamine X is 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM). The bis(4-aminophenoxy)benzene is at least one of 1,3-bis(4-aminophenoxy)benzene and 1,4-bis(4-aminophenoxy)benzene.

[0009] The aliphatic diacid Z is at least one of aliphatic diacids containing 6 to 12 carbon atoms.

[0010] Preferably, the aliphatic diacid is at least one of adipic acid, azelaic acid, sebacic acid, undecanoic acid, and dodecanoic acid; more preferably, it is at least one of sebacic acid, undecanoic acid, or dodecanoic acid.

[0011] In polyamide PA XZ / YZ, the molar fraction of XZ is 50-90%, the molar fraction of YZ is 10-50%, and the total molar content of XZ and YZ is 100%. Preferably, the molar fraction of XZ is 60-80%.

[0012] In the molar values ​​of dicarboxylic acids and diamines forming the polyamide, the sum of the molar amounts of all diamines is substantially equal to the sum of the molar amounts of all dicarboxylic acids. "Substantially equal to" means that the maximum molar excess of dicarboxylic acids or diamines is 4%, preferably 2%, which means that the molar ratio of dicarboxylic acids to diamines is from 1.04:1 to 1:1.04, and preferably from 1.02:1 to 1:1.02.

[0013] This application also provides a method for preparing polyamide PA XZ / YZ, comprising the following steps: 1) Add components X, Y and Z to water to pre-saltize them and then feed them into the polymerization reactor for dehydration reaction, or directly feed components X, Y and Z into the polymerization reactor for dehydration reaction; 2) After the reaction is complete, the polyamide melt is discharged, and the melt is formed by casting through a die head, and then cooled and granulated.

[0014] In step 1), a suitable catalyst for accelerating the polymerization reaction may also be added to the reactor. The catalyst is a phosphorus-containing acid, such as at least one of H3PO2, H3PO3, H3PO4 and their salts or organophosphonic acid derivatives. The amount of the catalyst is such that the mass of the catalyst accounts for 4 to 6% of the mass of the reactants (the total mass of components X, Y and Z).

[0015] The amount of water used in step 1) is sufficient to completely dissolve the reactants; The dehydration reaction described in step 1) refers to a reaction at 260-320℃ for 2-8 hours; The process of removing the polyamide melt in step 2) is carried out by injecting nitrogen into the reactor after the reaction is completed to remove the water generated by the reaction, and then pressurizing to remove the polyamide melt.

[0016] In polymerization reactions, heating, stirring, and dehydration can efficiently remove water from the reaction system in a short time, thereby increasing the reaction rate and promoting the formation of amide bonds to achieve the desired molecular weight. The relative viscosity and corresponding molecular weight can be adjusted in a known manner.

[0017] The present invention also provides a polyamide composition comprising: A. 30-100 wt% of at least one of the aforementioned polyamides PA XZ / YZ; B. 0-70wt% of reinforcing materials and / or fillers; C. 0-50wt% additives and / or other polymers; The total weight of components A through C is 100 wt%.

[0018] Preferably, component B in the polyamide composition contains at least a certain amount of glass fibers and / or carbon fibers, which may be short fibers of 2-50 mm or continuous long fibers, and the glass fibers and / or carbon fibers have a circular or non-circular cross-section.

[0019] Preferably, component C in the polyamide composition includes at least one selected from the following additives and / or other polymers: impact modifiers, adhesion promoters, compatibilizers, crystallization promoters or retarders, flow aids, lubricants, release agents, pigments, plasticizers, stabilizers, processing aids, flame retardants, antistatic agents, conductive additives, and polymerization process additives.

[0020] The present invention also provides a plastic part comprising the aforementioned polyamide composition.

[0021] Preferably, the plastic part is prepared from the polyamide composition. The plastic part is a molded part, an extruded part, or a blow-molded part, and can be produced using standard processing techniques for polyamides. For example, molded parts can be produced in a conventional injection molding machine with a standard three-screw at a barrel temperature 10-60°C above the melting point. The mold temperature is set to 40-130°C, preferably 70-100°C.

[0022] The plastic parts described in this invention can be used in medical devices, especially medical devices and equipment requiring steam sterilization; food utensils; automobiles; electronics and electrical appliances, especially portable electronic devices such as mobile phones, smartwatches, smart bracelets, portable computers, game consoles, VR glasses, tablets, cameras, etc.; sports equipment; fluid pipelines for non-automotive applications; mechanical engineering; leisure; toys; and measurement and control technology.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects: The polyamide PA XZ / YZ and its composition obtained in this invention have a higher glass transition temperature than traditional long-chain nylons, alicyclic nylons such as TR90, resulting in better temperature resistance and boiling resistance. At the same time, they maintain low water absorption, high toughness, and a lighter color. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0025] Example 1 A polyamide, the preparation method of which includes the following steps: 1) Add 10 kg of deionized water to a 50 L automated polymerization reactor equipped with a stirrer, then add 20 kg of a mixture of diacid and diamine with the molar ratio corresponding to the ratio in Table 1, and then add 1 g of phosphoric acid. The dehydration reaction is carried out for 4.5 h at a pressure of 20 bar and a temperature of 285 °C in the polymerization reactor. 2) After the reaction, nitrogen gas is injected to remove the water generated by the reaction, and then the polyamide melt is discharged under pressure. The melt is formed by casting through a die head and then cooled and granulated.

[0026] Table 1. Molar ratio of each raw material added during the polymerization reaction

[0027] Example 2 The particles obtained in Example 1 were dried in a vacuum oven at 80°C for 8 hours, then injection molded at 280°C, and their various properties were tested.

[0028] Glass transition temperature refers to ISO 11357-2, tensile test refers to ISO 527-2, notched impact strength refers to ISO 179 / 1eA, water absorption refers to ISO 62, and color Lab value refers to ISO 11664.

[0029] Table 2 shows the performance test results of various polymers in Example 1.

[0030] Table 2 shows that the polyamide with the bis(4-aminophenoxy)benzene copolymer component of this application exhibits significantly higher glass transition temperature, higher tensile strength, and higher impact strength compared to traditional long-chain polyamides and alicyclic polyamides, with comparable water absorption. The higher glass transition temperature and comparable water absorption result in higher resistance to boiling. Furthermore, when the copolymer component is suitable (e.g., PA-5), it can maintain a breakage elongation and yellow index (b<3.0) comparable to TR90. Conversely, while the glass transition temperature of the copolymer increases when p-phenylenediamine is used, the toughness (impact and breakage elongation) decreases significantly, and the yellow index increases dramatically, rendering it impractical.

[0031] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A polyamide PA XZ / YZ, characterized in that... It is polymerized from the following components: X is an alicyclic diamine, 3,3'-dimethyl-4,4-diaminodicyclohexylmethane; Y is bis(4-aminophenoxy)benzene; Z is at least one of sebacic acid, undecanoic acid, and dodecanoic acid; In polyamide PA XZ / YZ, the molar fraction of XZ is 50-90%, the molar fraction of YZ is 10-50%, and the total molar content of XZ and YZ is 100%.

2. The polyamide PA XZ / YZ according to claim 1, characterized in that: The bis(4-aminophenoxy)benzene is at least one of 1,3-bis(4-aminophenoxy)benzene and 1,4-bis(4-aminophenoxy)benzene.

3. The polyamide PA XZ / YZ according to claim 1, characterized in that: The molar ratio of diacid to diamine is 1.04:1 to 1:1.

04.

4. A method for preparing polyamide PA XZ / YZ according to any one of claims 1-3, characterized in that... Includes the following steps: 1) Add components X, Y and Z to water to pre-saltize them and then feed them into the polymerization reactor for dehydration reaction, or directly feed components X, Y and Z into the polymerization reactor for dehydration reaction; 2) After the reaction is complete, the polyamide melt is discharged, and the melt is formed by casting through a die head, and then cooled and granulated.

5. The method for preparing polyamide PA XZ / YZ according to claim 4, characterized in that: In step 1), a catalyst for accelerating the polymerization reaction is also added to the reactor. The catalyst is at least one of H3PO2, H3PO3, H3PO4, hypophosphite, phosphite, and phosphate. The amount of catalyst used is such that the mass of the catalyst accounts for 4-6% of the mass of the reactants. The amount of water used in step 1) is sufficient to completely dissolve the reactants; The dehydration reaction described in step 1) refers to a reaction at 260-320℃ for 2-8 hours; The process of removing the polyamide melt in step 2) is carried out by injecting nitrogen into the reactor after the reaction is completed to remove the water generated by the reaction, and then pressurizing to remove the polyamide melt.

6. A polyamide composition, characterized in that... Include: A. 30-100 wt% of at least one polyamide PA XZ / YZ; B. 0-70wt% of reinforcing materials and / or fillers; C. 0-50wt% additives and / or other polymers; The total weight of components A through C is 100 wt%. The polyamide PA XZ / YZ in component A is the polyamide PA XZ / YZ as described in any one of claims 1-3.

7. The polyamide composition according to claim 6, characterized in that: Component B in the composition comprises at least glass fiber and / or carbon fiber; The additives in component C of the composition are selected from at least one of the following: impact modifiers, adhesion promoters, compatibilizers, crystallization promoters or retardants, flow aids, lubricants, release agents, pigments, plasticizers, stabilizers, flame retardants, antistatic agents, and conductive additives.

8. A plastic part, characterized in that... It is prepared from the polyamide composition according to claim 6 or 7.

9. The application of the plastic parts according to claim 8 in the fields of medical devices, food utensils, automobiles, portable electronic devices, sports equipment, non-automotive fluid lines, toys, and measurement and control technologies.

10. The application of the plastic parts according to claim 8 in medical devices and equipment requiring steam sterilization, mobile phones, smartwatches, smart bracelets, portable computers, game consoles, VR glasses, and cameras.

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