A polyamide composite material and its preparation method and application

Abstract

The present invention discloses a polyamide composite material, a preparation method thereof and an application thereof. The polyamide composite material comprises the following components, measured by weight: 40-60 parts of a copolymerized polyamide resin; 35-80 parts of an aromatic polyamide resin; and 0.5-5 parts of a rare earth metal salt; the copolymerized polyamide resin is a copolymer of caprolactam and PA66 salt. The present invention preferably selects a copolymerized polyamide resin, adds a certain proportion of aromatic polyamide, and simultaneously adds a rare earth metal salt. Under the action of the rare earth metal salt, the copolymerized polyamide and the aromatic polyamide can be well combined, the crystallization temperature can be lowered, the toughness can be improved, and a high-barrier polyamide composite material with good water vapor barrier properties and excellent moisture and heat resistance can be prepared (water vapor permeability ≤3.0g / mm 2 24h, and can still maintain good toughness after being treated under hot and humid conditions of 60℃ and 90% humidity for 5h).

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polyamide composite material and a preparation method and application thereof. Background Art

[0002] With the continuous development of polymer materials, polyamide (PA) has an increasingly important position in the field of packaging applications. Compared with traditional materials such as metal and glass, polyamide has the advantages of light weight, easy molding and easy processing. However, its barrier properties are poor (especially water vapor barrier properties), and the barrier properties are unstable and easily affected by temperature and humidity (the barrier properties will decrease with the increase of temperature and humidity). In addition, due to the strong polarity of the amide group in the polyamide molecular chain, it is easy to form hydrogen bonds with water molecules in the environment. In high temperature and high humidity environments, it is very easy to absorb water and cause toughness deterioration. This greatly limits the application range of polyamide materials. Therefore, it is necessary to study how to improve the barrier properties and toughness of polyamide.

[0003] Prior art applications include Chinese patent application CN112094498A, which describes a polyamide material that effectively blocks oxygen and carbon dioxide by combining a polyamide resin and a thermoplastic polyester as the base resins and adding an additive containing a specific functional group. Similarly, Chinese patent application CN112739779A discloses an MXD6 resin containing plate-shaped talc with an aspect ratio exceeding 18 to enhance the material's barrier properties. However, these solutions primarily improve the polyamide's oxygen barrier properties, while their water vapor barrier capabilities are limited, and the material's toughness remains unresolved. Summary of the Invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a high-barrier polyamide material with good water vapor barrier properties and the ability to maintain good toughness under high temperature and high humidity conditions.

[0005] The present invention is achieved through the following technical solutions:

[0006] A polyamide composite material, comprising the following components in parts by weight:

[0007] 40-60 parts of copolyamide resin;

[0008] 35-80 parts of aromatic polyamide resin;

[0009] 0.5-5 parts of rare earth metal salt;

[0010] The copolyamide resin is a copolymer of caprolactam and PA66 salt.

[0011] Preferably, the polyamide composite material comprises the following components in parts by weight:

[0012] 45-55 parts of copolyamide resin;

[0013] 50-65 parts of aromatic polyamide resin;

[0014] 1-3 parts of rare earth metal salt.

[0015] The PA66 salt described in the present invention refers to a product produced by neutralization, crystallization, centrifugal separation and other processes of adipic acid and hexamethylenediamine, and is an intermediate in the polymerization of PA66.

[0016] The copolyamide resin of the present invention can be purchased commercially or prepared by itself. The present invention has no special requirements for the preparation method of the copolyamide resin. A certain proportion of caprolactam is added to the polymerization process of PA66 to carry out polymerization to obtain the copolyamide resin.

[0017] The present invention utilizes a polyamide resin copolymerized with caprolactam and PA66 salt, which readily forms hydrogen bonds, thereby reducing water vapor transmission rate and improving the barrier properties of the material. Preferably, the weight content of caprolactam in the copolyamide resin is 2-15%, more preferably 3-10%. The weight content of caprolactam in the copolyamide resin can be determined according to the GB / T 5009-2003 standard.

[0018] Preferably, the melting point of the copolyamide resin is 240-265° C., more preferably 245-260° C. Too high a melting point will reduce the toughness of the material.

[0019] Preferably, the aromatic polyamide resin of the present invention is selected from any one or more of PA MXD6 or PPA.

[0020] Preferably, the glass transition temperature of the aromatic polyamide resin is 100-120°C. Within the preferred range, aromatic polyamide resins with higher glass transition temperatures are more conducive to improving the barrier properties of the material, while excessively high glass transition temperatures can reduce the toughness of the material. The glass transition temperature is tested in accordance with the standard GB / T 19466-2004.

[0021] Preferably, the weight ratio of the copolymerized polyamide resin to the aromatic polyamide resin is (0.6-1.5):1.

[0022] Preferably, the rare earth metal salt is an acidified rare earth metal salt; more preferably, it is a rare earth metal salt treated with phosphoric acid.

[0023] Preferably, the rare earth metal salt is selected from any one or more of lanthanum salts; the lanthanum salt is preferably any one or more of lanthanum chloride, lanthanum nitrate or lanthanum acetate, more preferably lanthanum chloride.

[0024] Further preferably, in the polyamide composite material of the present invention, the percentage of the rare earth metal salt is 0.4%-5%.

[0025] According to the material properties, the polyamide composite material of the present invention further comprises 1-5 parts by weight of an auxiliary agent; the auxiliary agent is selected from any one or more of an antioxidant, a lubricant or a nucleating agent.

[0026] The antioxidant can be selected from any one or more of antioxidant 1098, antioxidant 1010, antioxidant 1076 or antioxidant 168.

[0027] The lubricant can be selected from any one or more of E wax, fatty acid ester or hyperbranched amide.

[0028] The nucleating agent can be selected from any one or more of boron nitride, talc, and the like.

[0029] The present invention also provides a method for preparing the polyamide composite material, comprising the following steps:

[0030] S1. First, add phosphoric acid to the rare earth metal salt for acidification, wherein the ratio of the rare earth metal salt to the phosphoric acid is 1 g: (5-20) mL to obtain the acidified rare earth metal salt;

[0031] S2. Premix the acidified rare earth metal salt with other components according to the proportions, mix them evenly, and then put them into a twin-screw extruder for melt mixing, extrusion and granulation to prepare a polyamide composite material; wherein the twin-screw extruder has a screw aspect ratio of 40-48:1, a barrel temperature of 250-300°C, and a screw speed of 200-550 rpm.

[0032] The present invention mixes the copolymerized polyamide 66 material and the aromatic nylon in a suitable proportion, and then adds an acidified rare earth metal salt. During the melt blending modification, the degradation of the nylon can be appropriately induced in the presence of an inorganic acid. The carboxyl and hydroxyl groups generated by the degradation can reduce the crystallization temperature of the material under the action of the metal salt. At the same time, the compatibility of the copolymerized polyamide and the semi-aromatic polyamide can be improved, the fusion effect of the material can be increased, the toughness of the material can be effectively improved, the barrier performance is more superior, the material has a stable structure in a hot and humid environment and is not easy to degrade. The material can effectively block the passage of water vapor and maintain stable performance.

[0033] The present invention also provides the use of the polyamide composite material in the field of food packaging or as a component material used in a high-temperature and high-humidity environment (temperature>50°C, humidity>50%).

[0034] The present invention has the following beneficial effects:

[0035] The present invention prepares a high barrier polyamide composite material with good water vapor barrier properties and excellent heat and humidity resistance (water vapor transmission rate ≤3.0g / mm2) by optimizing the copolymerized polyamide resin, adding a certain proportion of aromatic polyamide, and adding rare earth metal salt. Under the action of the rare earth metal salt, the copolymerized polyamide and aromatic polyamide can be well combined, the crystallization temperature can be lowered, and the toughness can be improved. 2 24h, and can still maintain good toughness after being treated under hot and humid conditions of 60℃ and 90% humidity for 5h). DETAILED DESCRIPTION

[0036] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0037] The raw materials used in the examples and comparative examples of the present invention are described below, but are not limited to these materials:

[0038] Copolyamide resin 1: PA66 EP26CL, caprolactam content 5.5% by weight, melting point 255°C, Huafeng Group Corporation;

[0039] Copolyamide resin 2: C2710, caprolactam content 12% by weight, melting point 244°C, Shenma Group;

[0040] Copolyamide resin 3: FYR25T30, caprolactam content 2% by weight, melting point 256°C, Shenma Group;

[0041] Homopolymer polyamide resin: PA6621SPC, Osend;

[0042] Aromatic polyamide resin 1: PA MXD6, glass transition temperature of 102°C, Mitsubishi Corporation, Japan;

[0043] Aromatic polyamide resin 2: PPA N200, glass transition temperature 123°C, Zhejiang Xinhecheng Special Materials Co., Ltd.

[0044] Rare earth metal salt 1: lanthanum chloride, Shanghai Longjin Company;

[0045] Rare earth metal salt 2: lanthanum nitrate, Jining Zhongkai New Materials Co., Ltd.;

[0046] Rare earth metal salt 3: lanthanum acetate, Wuhan Kemik Biopharmaceutical Technology Co., Ltd.;

[0047] Additive: Antioxidant 1098, commercially available.

[0048] Preparation methods of Examples 1-15 and Comparative Examples 1-5:

[0049] S1. First, phosphoric acid was added to the rare earth metal salt for acidification, wherein the ratio of the rare earth metal salt to the phosphoric acid was 1 g: 10 mL to obtain the acidified rare earth metal salt;

[0050] S2. According to the ratio, the acidified rare earth metal salt is pre-mixed with other components, and after uniform mixing, the mixture is put into a twin-screw extruder for melt mixing, and extruded into granules to prepare a polyamide composite material; wherein, the screw length-to-diameter ratio of the twin-screw extruder is 48:1, and the temperature of zone 1 of the twin-screw extruder is 250-270℃, the temperature of zone 2 is 260-280℃, the temperature of zone 3 is 260-280℃, the temperature of zone 4 is 260-280℃, the temperature of zone 5 is 270-290℃, the temperature of zone 6 is 280-300℃, the temperature of zone 7 is 270-290℃, the temperature of zone 8 is 260-280℃, and the temperature of zone 9 is 240-260℃; the screw speed is 350rpm.

[0051] Preparation method of Comparative Example 6:

[0052] According to the ratio, the components are pre-mixed, mixed evenly, and then put into a twin-screw extruder for melt mixing, extrusion and granulation to prepare a polyamide composite material; wherein the screw length-diameter ratio of the twin-screw extruder is 48:1, the temperature of zone 1 of the twin-screw extruder is 250-270°C, the temperature of zone 2 is 260-280°C, the temperature of zone 3 is 260-280°C, the temperature of zone 4 is 260-280°C, the temperature of zone 5 is 270-290°C, the temperature of zone 6 is 280-300°C, the temperature of zone 7 is 270-290°C, the temperature of zone 8 is 260-280°C, and the temperature of zone 9 is 240-260°C; and the screw speed is 350rpm.

[0053] Related performance test methods:

[0054] The prepared polyamide composite material was injection molded in an injection molding machine at 295° C., a rated speed of 50% and a pressure of 60 bar using a 280T injection molding machine.

[0055] (1) Barrier performance test: Prepared samples and 0.55 mm thin sheets are tested in a water vapor transmission rate test system according to GB / T 31355 standard. The dry chamber is kept at 5% humidity and the wet chamber is kept at 89% humidity. The barrier performance of the material is tested by measuring the weight change of the thin sheet after 24 hours.

[0056] (2) Material toughness performance test: The material is injection molded into 80*10*0.8mm thick specimens. After being treated at 60℃ and 90% humidity for 5 hours, the specimens are folded 90 degrees along the middle of the specimens, and then folded 180 degrees in the opposite direction. The material is observed for breaking and cracking: if there are obvious cracks and the crack length is greater than 7mm, it is "severe cracking"; if there are obvious cracks and the crack length is 2-7mm, it is "moderate cracking"; if there are no obvious cracks and the crack length is less than 2mm, it is "slight cracking"; if there are no cracks, it is "no cracking". The better the toughness of the material, the less likely it is to crack.

[0057] Table 1: Distribution ratios of each group in Examples 1-7 (by weight) and related performance test results

[0058] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Copolyamide resin 1 50 50 50 50 50 40 60 Aromatic polyamide resin 1 55 35 80 55 55 55 55 Lanthanum chloride 2.5 2.5 2.5 0.5 5 2.5 2.5 <![CDATA[Water vapor transmission rate / g / mm 2 ·24 h]]> 1.1 2.8 1.5 2.3 2.6 2.1 2.4 Toughness test No cracking No cracking Slight cracking Slight cracking No cracking No cracking No cracking

[0059] Table 2: Distribution ratios of each group in Examples 10-14 (by weight) and related performance test results

[0060] Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Copolyamide resin 1 50 50 50 55 45 Copolyamide resin 2 50 Copolyamide resin 3 50 Aromatic polyamide resin 1 55 55 55 55 50 65 Aromatic polyamide resin 2 55 Lanthanum chloride 2.5 2.5 2.5 3 1 Lanthanum nitrate 2.5 Lanthanum acetate 2.5 antioxidants / / / / / 1.2 1.6 <![CDATA[Water vapor transmission rate / g / mm 2 ·24h]]> 1.6 2.4 2.7 1.9 2.1 2.0 1.9 Toughness test No cracking No cracking No cracking No cracking No cracking No cracking No cracking

[0061] Table 3: Distribution ratios of each group in Comparative Examples 1-7 (by weight) and related performance test results

[0062] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Copolyamide resin 1 50 50 105 50 50 50 Homopolymer polyamide resin 50 Aromatic polyamide resin 1 55 25 / / 55 55 55 Lanthanum chloride 2.5 2.5 2.5 2.5 0.2 7 / <![CDATA[Water vapor transmission rate / g / mm 2 ·24h]]> 5.8 5.5 6.9 5.9 6.0 5.2 6.6 Toughness test Severe cracking No cracking No cracking Moderate cracking Moderate cracking Slight cracking Severe cracking

[0063] From the results of the above examples, it can be seen that the present invention prepares a high barrier polyamide composite material with good water vapor barrier properties and excellent heat and moisture resistance (water vapor transmission rate ≤3.0g / mm2) by preferably copolymerizing polyamide resin, adding a certain proportion of aromatic polyamide, and adding rare earth metal salt. 2 24h, and can still maintain good toughness after being treated under hot and humid conditions of 60℃ and 90% humidity for 5h).

[0064] Comparative Example 1 uses a homopolymer polyamide resin, which has a high water vapor permeability and poor toughness.

[0065] In comparative examples 2 / 3, the amount of aromatic polyamide resin added was too little or not added, and thus good water vapor barrier performance could not be achieved.

[0066] In comparative examples 5 / 7, too little lanthanum chloride was added or no lanthanum chloride was added, resulting in poor water vapor barrier properties and toughness of the material.

[0067] In Comparative Example 6, excessive addition of lanthanum chloride leads to an increase in the water vapor permeability of the material and a deterioration in toughness.

Claims

1. A polyamide composite material, characterized in that: Calculated by weight, it includes the following components: 40-60 parts of copolyamide resin; 35-80 parts of aromatic polyamide resin; 0.5-5 parts of rare earth metal salt; The copolyamide resin is a copolymer of caprolactam and PA66 salt; The aromatic polyamide resin is selected from any one or more of PA MXD6 and PPA; The rare earth metal salt is a rare earth metal salt acidified with an inorganic acid.

2. The polyamide composite material according to claim 1, characterized in that Calculated by weight, it includes the following components: 45-55 parts of copolyamide resin; 50-65 parts of aromatic polyamide resin; 1-3 parts of rare earth metal salt.

3. The polyamide composite material according to claim 1, characterized in that The weight content of caprolactam in the copolymerized polyamide resin is 2-15%.

4. The polyamide composite material according to claim 3, characterized in that The weight content of caprolactam in the copolymerized polyamide resin is 3-10%.

5. The polyamide composite material according to claim 1, characterized in that The melting point of the copolyamide resin is 240-265°C.

6. The polyamide composite material according to claim 5, characterized in that The melting point of the copolyamide resin is 245-260°C.

7. The polyamide composite material according to claim 1, characterized in that The glass transition temperature of the aromatic polyamide resin is 100-120°C.

8. The polyamide composite material according to claim 1, characterized in that The rare earth metal salt is a rare earth metal salt that has been treated with phosphoric acid.

9. The polyamide composite material according to claim 1, characterized in that The rare earth metal salt is selected from any one or more of lanthanum salts; the lanthanum salt is selected from any one or more of lanthanum chloride, lanthanum nitrate or lanthanum acetate.

10. The polyamide composite material according to claim 9, characterized in that: The lanthanide salt is selected from lanthanum chloride.

11. The polyamide composite material according to claim 1, characterized in that: Calculated by weight, the invention further comprises 1-5 parts of auxiliary agents; the auxiliary agents are selected from any one or more of antioxidants, lubricants or nucleating agents.

12. The method for preparing a polyamide composite material according to any one of claims 1 to 11, characterized in that: The following steps are involved: S1. First, add phosphoric acid to the rare earth metal salt for acidification, wherein the ratio of the rare earth metal salt to the phosphoric acid is 1 g: (5-20) mL to obtain the acidified rare earth metal salt; S2. Premix the acidified rare earth metal salt with other components according to the proportions, mix them evenly, and then put them into a twin-screw extruder for melt mixing, extrusion and granulation to prepare a polyamide composite material; wherein the twin-screw extruder has a screw aspect ratio of 40-48:1, a barrel temperature of 250-300°C, and a screw speed of 200-550 rpm.

13. Use of the polyamide composite material according to any one of claims 1 to 11 in the field of food packaging or as a component material used in high temperature and high humidity environments.