A GMA graft-modified copolymer, its preparation method, and toughened polyamide

Abstract

This invention provides a GMA graft-modified copolymer, its preparation method, and a toughening polyamide, relating to the field of polymer materials technology. The GMA graft-modified copolymer provided by this invention is prepared by melt grafting of the following raw materials in parts by weight: 50-95 parts EMA and / or EBA; 3-5 parts GMA; 0.1-0.6 parts peroxide initiator; 2-5 parts co-reactant; and 0.5-1 parts lubricant. The preparation method includes: premixing GMA, co-reactant, lubricant, and peroxide initiator to obtain a masterbatch; adding the masterbatch and EMA and / or EBA to a twin-screw extruder, melt grafting at 140-200°C, and extruding to obtain the GMA graft-modified copolymer. Using the GMA graft-modified copolymer as a toughening agent for polyamide can significantly improve the elongation at break and notched impact strength of the toughened polyamide.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a GMA graft-modified copolymer, its preparation method, and a toughened polyamide. Background Technology

[0002] Polyamide (PA) materials are widely used in the automotive, electronics, and industrial sectors due to their excellent mechanical properties, heat resistance, and chemical resistance. However, PA materials exhibit poor toughness at low temperatures, particularly at -40°C, where they easily become brittle, severely limiting their application in cold environments. To address the insufficient toughness of polyamide (PA) materials at low temperatures, toughening modification techniques are commonly employed. Among various toughening modification methods, elastomer toughening has become one of the most widely used methods due to its stable effects and wide applicability.

[0003] However, in the process of toughening PA with elastomers, the compatibility between the elastic toughening agent and the PA matrix is ​​poor. Insufficient compatibility can easily lead to weakened interfacial bonding, thereby deteriorating the mechanical property stability of the material and significantly restricting the achievement of the toughening effect. To improve the compatibility between the toughening agent and the PA matrix, it is usually necessary to functionalize the toughening agent to give it functional groups that can react with PA. In the prior art, maleic anhydride (MAH) grafted polyolefin elastomers (such as POE-g-MAH) are commonly used PA toughening agents. Patent document CN102391432B discloses a high-flowability ethylene-α-octene graft copolymer and its preparation method. This method uses a side-feeding technique to achieve a higher grafting rate and lower gel content in the product, resulting in better flow properties and excellent impact resistance when applied to polyamide.

[0004] However, the MAH functional group can only react with the amine group (-NH2) at the end of the PA chain, and cannot react with the carboxyl group (-COOH) at the other end of the PA chain. This results in low reaction efficiency and poor compatibility toughening effect. In addition, the poor compatibility between the toughening substrate POE and PA further affects the toughening effect.

[0005] Therefore, there is an urgent need to develop a new type of PA toughening agent that can react with both the amine and carboxyl groups of PA to improve compatibility and toughening effect, especially to improve the toughness of PA materials under low temperature conditions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a GMA graft-modified copolymer, its preparation method, and a toughened polyamide. The GMA graft-modified copolymer exhibits good compatibility with polyamide and can significantly improve the elongation at break and low-temperature notched impact strength of polyamide.

[0007] The specific technical solution of this invention is as follows:

[0008] In a first aspect, the present invention provides a GMA graft-modified copolymer comprising the following raw materials in parts by weight:

[0009] 50-95 parts of ethylene-methyl acrylate copolymer and / or ethylene-butyl acrylate copolymer,

[0010] Peroxide initiator 0.1-0.6 parts,

[0011] 3-5 parts of glycidyl methacrylate

[0012] 2-5 parts of co-reactant

[0013] Lubricant 0.5-1 part;

[0014] The peroxide initiator is at least one of cumene peroxide and 2,5-dimethyl-2,5-di-tert-butylperoxide.

[0015] In one possible implementation, the co-reactant is styrene.

[0016] In one possible implementation, the lubricant is methyl silicone oil.

[0017] Secondly, the present invention provides a method for preparing the above-mentioned GMA graft-modified copolymer, comprising the following steps:

[0018] S1. The mass fractions of glycidyl methacrylate, peroxide initiator, co-reactant and lubricant are premixed to obtain masterbatch;

[0019] S2. The masterbatch mentioned in step S1 is mixed evenly with the ethylene-methyl acrylate copolymer and / or ethylene-butyl acrylate copolymer in the specified mass fractions and then added to an extruder. The mixture is melt-grafted and extruded at 140-220 °C to obtain the GMA grafted modified copolymer.

[0020] In one possible implementation, the processing temperature of the extruder is: Zone 1 140-145 ℃, Zone 2 170-180 ℃, Zone 3 185-190 ℃, Zone 4 190-195 ℃, Zone 5 190-195 ℃, Zone 6 190-195 ℃, and die head 200-220 ℃.

[0021] In one possible implementation, the extruder is a twin-screw extruder.

[0022] Thirdly, the present invention provides a toughened polyamide comprising 85-95 wt% of a polyamide matrix and 5-15 wt% of the above-mentioned GMA graft-modified copolymer.

[0023] In one possible implementation, the polyamide matrix is ​​at least one of PA6 and PA66.

[0024] In one possible implementation, the toughened polyamide has an elongation at break of ≥50% at room temperature.

[0025] In one possible implementation, the toughened polyamide has a notched impact strength ≥70 kJ / m² at room temperature.

[0026] In one possible implementation, the toughened polyamide has a low-temperature notched impact strength of ≥28kJ / m² at -40 °C.

[0027] The positive and progressive effects of this invention are as follows:

[0028] Compared with the prior art, the GMA graft-modified copolymer, its preparation method, and the toughened polyamide provided by the present invention have the following three beneficial effects:

[0029] I. By grafting GMA onto ethylene-methyl acrylate copolymer and / or ethylene-butyl acrylate copolymer matrices, the reactivity with the terminal amino and carboxyl groups of polyamides is significantly enhanced. When applied to polyamide matrices, it can greatly improve the compatibility with polyamides and significantly increase the elongation at break and low-temperature notched impact strength of polyamides. Moreover, its toughening effect is superior to the current mainstream POE-g-MAH (maleic anhydride-grafted polyolefin elastomer), and it also has a significant competitive advantage in raw material costs.

[0030] 2. By adjusting the compounding ratio of ethylene-methyl acrylate copolymer and / or ethylene-butyl acrylate copolymer, the toughness requirements of polyamides with different melt viscosities can be precisely adapted. In particular, it performs outstandingly in improving the low-temperature toughness of polyamides (such as -40℃ notched impact strength), solving the problems of poor compatibility of conventional toughening agents with polyamides of different viscosities and insufficient low-temperature toughness.

[0031] Third, the production process of GMA grafted modified copolymers is simple and easy to implement. Melt grafting can be completed on conventional extruders. This not only ensures that EMA and / or EBA grafted materials achieve a high grafting rate, but also requires no special modification to the production equipment. The process is highly stable and easy to achieve large-scale industrial production. Detailed Implementation

[0032] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the present invention.

[0033] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.

[0035] Terminology Explanation

[0036] GMA is short for glycidyl methacrylate, an ester compound with the molecular formula C7H. 10 O3, also known as 2,3-epoxypropyl methacrylate.

[0037] The specific technical solution of this invention is as follows:

[0038] In a first aspect, the present invention provides a GMA graft-modified copolymer comprising the following raw materials in parts by weight:

[0039] 50-95 parts of ethylene-methyl acrylate copolymer (EMA) and / or ethylene-butyl acrylate copolymer (EBA)

[0040] Peroxide initiator 0.1-0.6 parts,

[0041] Glycidyl methacrylate (GMA) 3-5 parts,

[0042] 2-5 parts of co-reactant

[0043] Lubricant 0.5-1 part;

[0044] The peroxide initiator is at least one of cumene peroxide (DCP) and 2,5-dimethyl-2,5-di-tert-butylperoxide (BPDP).

[0045] This invention provides a GMA graft-modified copolymer that achieves good compatibility with polyamide and significantly improves the elongation at break and low-temperature notched impact strength of polyamide through the synergistic effect of five core components: EMA and / or EBA copolymer matrix, GMA graft-modified units, peroxide initiator, co-reactant, and lubricant. The acrylate groups in the EMA and / or EBA molecular chains are polar groups, which can reduce the interfacial tension between EMA and / or EBA and PA through polar-polar interactions, initially improving the dispersibility with PA. Furthermore, EMA and / or EBA themselves are excellent toughness materials. When present as a dispersed phase in the PA matrix, they can act as numerous elastic microdomains, effectively absorbing and dispersing impact energy. 50-95 parts of EMA and / or EBA ensure that the GMA graft-modified copolymer contains sufficient flexible segments to provide a toughening effect. The epoxy group (-COC-) of GMA has high reactivity and can undergo ring-opening reactions with the terminal amino (-NH2) and terminal carboxyl (-COOH) groups of polyamide. On the one hand, this is beneficial to further improve the compatibility between GMA graft-modified copolymers and polyamides. On the other hand, it can directly connect GMA graft-modified copolymers with polyamide molecular chains, so that flexible GMA graft-modified copolymers and rigid polyamides form chemically bonded interfaces. Under stress, stress can be efficiently transferred to flexible GMA graft-modified copolymers through the chemical bonds formed by epoxy groups and terminal amino and carboxyl groups, thereby improving the elongation at break and low-temperature notched impact strength of polyamides. 3-5 parts of GMA are sufficient to form a sufficiently dense chemical bond network at the interface between GMA graft-modified copolymers and polyamides. Cumene peroxide and 2,5-dimethyl-2,5-di-tert-butylperoxide are both organic peroxides. When heated, they decompose to produce free radicals. These free radicals preferentially abstract tertiary C-hydrogen atoms from the EMA and / or EBA molecular chains, generating macromolecular free radicals on the EMA and / or EBA backbone. The GMA monomer comes into contact with the macromolecular free radicals and undergoes a graft copolymerization reaction, thereby chemically linking the GMA molecules to the EMA and / or EBA molecular chains. An initiator dosage of 0.1-0.6 parts provides a sufficient number of free radicals, ensuring that the GMA graft-modified copolymer has a sufficient GMA grafting rate, while avoiding the cross-linking reaction of the EMA and / or EBA matrix caused by excessive free radicals, which would cause the GMA graft-modified copolymer to change from a flexible elastomer to a rigid cross-linker, thus losing its toughening effect on PA. The core role of 2-5 parts of co-reactant is to work synergistically with the peroxide initiator to regulate the direction of free radical reaction, maximize the GMA grafting rate, minimize harmful crosslinking side reactions, and maintain the good flowability and toughness of GMA graft-modified copolymers even at high grafting rates, thereby achieving a significant improvement in the elongation at break and impact strength of polyamide.Adding 0.5-1 part of lubricant can reduce the processing viscosity of GMA graft-modified copolymer and PA, forming a lubricating film at the interface of the processed melt, reducing intermolecular friction, and enabling the GMA graft-modified copolymer to be uniformly dispersed into fine particles, ensuring the uniform dispersion of the flexible dispersed phase (GMA graft-modified copolymer) in the polyamide. The GMA graft-modified copolymer provided by this invention, through the precise proportioning and synergistic effect of the above-mentioned technical features, not only solves the compatibility problem between elastic toughening agents and polyamide, but also specifically enhances the toughness and impact resistance of polyamide (especially low-temperature impact resistance), providing a feasible technical path for the low-temperature application of polyamide.

[0046] In one possible implementation, the co-reactant is styrene. When the co-reactant is styrene, the styrene monomer can react with the free radicals generated by the decomposition of the peroxide initiator to form styrene free radicals. During the grafting reaction, the free radicals generated by the decomposition of the peroxide initiator have a short lifespan and are prone to termination, while styrene free radicals, due to their conjugated stable structure, can prolong their existence time, increase the chance of the free radicals reacting with the EMA and / or EBA matrix and GMA, further promoting the grafting of GMA, thereby increasing the grafting rate and thus more effectively improving the compatibility and toughening effect with polyamides.

[0047] In one possible implementation, the lubricant is methyl silicone oil. When the lubricant is methyl silicone oil, it not only reduces the processing viscosity of the GMA graft-modified copolymer and PA, promoting dispersion, but also, due to its good chemical stability, prevents it from reacting chemically with EMA and / or EBA, GMA, polyamide, etc., during processing, and avoids negatively affecting the mechanical properties of polyamide, such as elongation at break and low-temperature notched impact strength. Furthermore, it can form an extremely thin protective film on the surface of polyamide, reducing the erosion of polyamide by ultraviolet light, oxygen, etc., and delaying the aging process of polyamide.

[0048] Secondly, the present invention provides a method for preparing the above-mentioned GMA graft-modified copolymer, comprising the following steps:

[0049] S1. The mass fractions of glycidyl methacrylate, peroxide initiator, co-reactant and lubricant are premixed to obtain masterbatch;

[0050] S2. The masterbatch mentioned in step S1 is mixed evenly with the ethylene-methyl acrylate copolymer and / or ethylene-butyl acrylate copolymer in the specified mass fractions and then added to an extruder. The mixture is melt-grafted and extruded at 140-220 °C to obtain the GMA grafted modified copolymer.

[0051] The method for preparing GMA graft-modified copolymers provided by this invention involves pre-mixing GMA, a peroxide initiator, a co-reactant, and a lubricant to form a masterbatch. This ensures uniform micro-scale dispersion of the raw materials during the pre-mixing stage. Subsequent mixing with an EMA and / or EBA matrix achieves secondary dispersion, which helps reduce the distribution deviation of GMA in the EMA and / or EBA matrix, laying the foundation for uniformity in the grafting reaction. Then, by controlling the grafting reaction temperature at 140-220 °C, the processing characteristics of the EMA and / or EBA matrix are compatible with the decomposition characteristics of the peroxide initiator, ensuring sufficient decomposition of the initiator to generate free radicals, thereby grafting GMA onto the EMA and / or EBA matrix to obtain the GMA graft-modified copolymer. Furthermore, the preparation method for GMA graft-modified copolymers is simple, and pre-mixing and extrusion can be achieved using conventional plastic processing equipment (high-speed mixer + twin-screw extruder), making it suitable for industrial production.

[0052] In one possible implementation, the extruder's processing temperature is: Zone 1 140-145℃, Zone 2 170-180℃, Zone 3 185-190℃, Zone 4 190-195℃, Zone 5 190-195℃, Zone 6 190-195℃, and Die Head 200-220℃. Setting the extruder's temperature in each zone to a gradient increase mode of "Zone 1 140-145℃, Zone 2 170-180℃, Zone 3 185-190℃, Zones 4-6 190-195℃, and Die Head 200-220℃" can adapt to the reaction characteristics and material processing requirements of GMA graft-modified copolymers. Zone 1, serving as the material inlet area, is set at 140-145°C, slightly higher than the melting temperature of the EMA and / or EBA matrix (EMA approximately 80-100°C, EBA approximately 70-90°C). This allows for slow melting of the EMA and / or EBA matrix while preventing premature decomposition of the peroxide initiator before the material is fully melted. Zone 2, at 170-180°C, triggers the slow decomposition of the peroxide initiator, generating initial free radicals. Zone 3, at 185-190°C, accelerates free radical generation. At this point, the material is fully melted and forms a homogeneous melt, ensuring that the free radicals interact effectively with the EMA and / or EBA matrix and GMA. The contact efficiency of the monomer initiates the grafting reaction; zones four to six are the main areas of the grafting reaction, and 190-195℃ can ensure the continuous decomposition of the initiator, so that the decomposition rate of the peroxide initiator matches the grafting reaction rate; the die head is the material outlet area, and appropriately increasing the temperature to 200-220℃ can reduce the melt viscosity, ensure the smooth extrusion molding of the grafted product, and at the same time avoid material retention and degradation caused by excessive die head pressure.

[0053] In one possible implementation, the extruder is a twin-screw extruder. Using a twin-screw extruder allows for two advantages: firstly, it disperses the masterbatch and EMA and / or EBA matrix into micron-sized melt streams, ensuring a uniform molecular-level distribution of additives such as GMA and peroxide initiators within the matrix; secondly, by adjusting the screw speed and pitch combination of the twin-screw extruder, the residence time of the material in the barrel can be precisely controlled, matching it with the decomposition rate of the peroxide initiator and the grafting reaction kinetics of GMA.

[0054] Thirdly, the present invention provides a toughened polyamide comprising 85-95 wt% of a polyamide matrix and 5-15 wt% of the above-mentioned GMA graft-modified copolymer.

[0055] In the toughened polyamide provided by this invention, a high proportion of 85-95 wt% polyamide is used to form a continuous phase, ensuring that the toughened polyamide maintains its original excellent mechanical strength and heat resistance. 5-15 wt% of GMA graft-modified copolymer is uniformly distributed in the polyamide matrix as a dispersed phase, which can provide the best compatibilization and toughening effect.

[0056] In one possible implementation, the polyamide matrix is ​​at least one of PA6 and PA66. PA6 has the advantages of good toughness and high processing fluidity, making it suitable for applications with high requirements for impact resistance and molding efficiency; PA66 has higher strength and better heat resistance, making it suitable for high-temperature and high-load conditions. The selection or combination of PA6 and PA66 can flexibly match the different requirements of various applications for strength, toughness, and heat resistance.

[0057] In one possible implementation, the toughened polyamide has an elongation at break of ≥50% at room temperature. An elongation at break of ≥50% indicates that the toughened polyamide has excellent flexibility, can undergo large deformation under stress without easily breaking, can effectively buffer external impacts, reduce the risk of direct fracture due to instantaneous stress concentration, and is suitable for structural components with high reliability requirements.

[0058] In one possible implementation, the toughened polyamide has a notched impact strength ≥70 kJ / m² at room temperature. When the toughened polyamide has a notched impact strength ≥70 kJ / m² at room temperature, it can still absorb a large amount of impact energy and is not easily broken even in the presence of defects such as notches and cracks, making it suitable for scenarios with high requirements for structural stability.

[0059] In one possible embodiment, the toughened polyamide has a notched impact strength ≥28 kJ / m² at -40 °C. At -40 °C, most polyamides are prone to embrittlement due to molecular chain stiffness, while a strength ≥28 kJ / m² is desirable. 2The notched impact strength allows toughened polyamide to effectively absorb energy and avoid brittle failure when subjected to low-temperature impacts (such as automotive parts in cold regions being hit by gravel or outdoor equipment being impacted after freezing).

[0060] The technical solution of the present invention will be further described below with reference to specific embodiments and comparative examples. All reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing. The instruments used in the embodiments are also commercially available.

[0061] Example 1

[0062] This embodiment provides a GMA-grafted modified EMA copolymer, which is prepared by melt grafting reaction from the following parts by weight of raw materials:

[0063] EMA 94 parts, BPDH 0.3 parts, GMA 3 parts, styrene 2 parts, silicone oil 0.5 parts.

[0064] The preparation method of GMA grafted modified EMA copolymer in this embodiment includes the following steps:

[0065] S1. Thoroughly mix 3 parts GMA, 2 parts styrene, 0.5 parts silicone oil and 0.3 parts BPDH to obtain the masterbatch;

[0066] S2. The masterbatch obtained in S1 is mixed with 94 parts of EMA and treated for 3-5 min. Then, it is added to a twin-screw extruder for melt grafting reaction. The temperature of each section of the twin-screw extruder is set as follows: Zone 1 140℃, Zone 2 180℃, Zone 3 190℃, Zone 4 195℃, Zone 5 195℃, Zone 6 195℃, and Die head 200℃. After the grafting reaction is completed in the extruder, the material is extruded and pelletized to obtain GMA grafted modified EMA copolymer.

[0067] Example 2

[0068] This embodiment provides a GMA-grafted modified EMA copolymer, which is prepared by melt grafting reaction from the following parts by weight of raw materials:

[0069] EMA 91 parts, BPDH 0.5 parts, GMA 5 parts, styrene 3 parts, silicone oil 0.5 parts.

[0070] The preparation method of GMA grafted modified EMA copolymer in this embodiment includes the following steps:

[0071] S1. Thoroughly mix 5 parts GMA, 3 parts styrene, 0.5 parts silicone oil and 0.5 parts BPDH to obtain the masterbatch;

[0072] S2. The masterbatch obtained in S1 is mixed with 91 parts of EMA and treated for 3-5 minutes. Then, it is added to a twin-screw extruder for melt grafting reaction. The temperature of each section of the twin-screw extruder is set as follows: Zone 1 140℃, Zone 2 180℃, Zone 3 190℃, Zone 4 195℃, Zone 5 195℃, Zone 6 195℃, and Die head 200℃. After the grafting reaction is completed in the extruder, the material is extruded and pelletized to obtain GMA grafted modified EMA copolymer.

[0073] Example 3

[0074] This embodiment provides a GMA-grafted modified EBA copolymer, which is prepared by melt grafting reaction from the following raw materials in parts by weight:

[0075] EBA 94 parts, BPDH 0.3 parts, GMA 3 parts, styrene 2 parts, silicone oil 0.5 parts.

[0076] The preparation method of GMA-grafted modified EBA copolymer in this embodiment includes the following steps:

[0077] S1. Thoroughly mix 3 parts GMA, 2 parts styrene, 0.5 parts silicone oil and 0.3 parts BPDH to obtain the masterbatch;

[0078] S2. The masterbatch obtained in S1 is mixed with 94 parts of EBA and treated for 3-5 min. Then, it is added to a twin-screw extruder for melt grafting reaction. The temperature of each section of the twin-screw extruder is set as follows: Zone 1 140 ℃, Zone 2 180 ℃, Zone 3 190 ℃, Zone 4 195 ℃, Zone 5 195 ℃, Zone 6 195 ℃, and the die head 200 ℃. After the grafting reaction is completed in the extruder, the material is extruded and pelletized to obtain GMA grafted modified EBA copolymer.

[0079] Example 4

[0080] This embodiment provides a GMA-grafted modified EBA copolymer, which is prepared by melt grafting reaction from the following raw materials in parts by weight:

[0081] EMA 91 parts, BPDH 0.5 parts, GMA 5 parts, styrene 3 parts, silicone oil 0.5 parts.

[0082] The preparation method of GMA-grafted modified EBA copolymer in this embodiment includes the following steps:

[0083] S1. Thoroughly mix 5 parts GMA, 3 parts styrene, 0.5 parts silicone oil and 0.5 parts BPDH to obtain the masterbatch;

[0084] S2. The masterbatch obtained in S1 is mixed with 91 parts of EBA and treated for 3-5 min. Then, it is added to a twin-screw extruder for melt grafting reaction. The temperature of each section of the twin-screw extruder is set as follows: Zone 1 140 ℃, Zone 2 180 ℃, Zone 3 190 ℃, Zone 4 195 ℃, Zone 5 195 ℃, Zone 6 195 ℃, and Die head 200 ℃. After the grafting reaction is completed in the extruder, the material is extruded and pelletized to obtain GMA grafted modified EBA copolymer.

[0085] Example 5

[0086] This embodiment provides a GMA-grafted modified EMA and EBA copolymer, which is prepared by melt grafting reaction from the following raw materials in parts by weight:

[0087] EMA 45.5 parts, EBA 45.5 parts, BPDH 0.5 parts, GMA 5 parts, styrene 3 parts, silicone oil 0.5 parts.

[0088] The preparation method of GMA-grafted modified EMA and EBA copolymer in this embodiment includes the following steps:

[0089] S1. Thoroughly mix 5 parts GMA, 3 parts styrene, 0.5 parts silicone oil and 0.5 parts BPDH to obtain the masterbatch;

[0090] S2. The masterbatch obtained in S1 is mixed with 45.5 parts EMA and 45.5 parts GBA and treated for 3-5 minutes. Then, it is added to a twin-screw extruder for melt grafting reaction. The temperature of each section of the twin-screw extruder is set as follows: Zone 1 140 ℃, Zone 2 180 ℃, Zone 3 190 ℃, Zone 4 195 ℃, Zone 5 195 ℃, Zone 6 195 ℃, and Die head 200 ℃. After the grafting reaction is completed in the extruder, the material is extruded and pelletized to obtain GMA grafted modified EMA and EBA copolymer.

[0091] Example 6

[0092] This embodiment provides a toughened polyamide comprising 85 wt% of a PA6 matrix and 15 wt% of the GMA-grafted modified EMA copolymer from Example 1.

[0093] The preparation method of the toughened polyamide in this embodiment includes the following steps:

[0094] D1. Add 15 wt% of the GMA grafted modified EMA copolymer prepared in Example 1 to 85 wt% of PA6 and mix evenly to obtain a preliminary mixture.

[0095] D2. Add antioxidants of type 168 and 1098, vinyl bis-stearamide (EBS) and calcium stearate lubricant to the initial mixture described in step D1, and mix evenly to obtain a mixture.

[0096] D3. The mixture described in step D2 is added to a twin-screw extruder, and after extrusion, pelleting and drying, the extrusion temperature is 220 ℃ and the drying temperature is 80 ℃ to obtain toughened polyamide.

[0097] Example 7

[0098] This embodiment provides a toughened polyamide comprising 85 wt% of a PA6 matrix and 15 wt% of the GMA-grafted modified EMA copolymer from Example 2.

[0099] The preparation method of the toughened polyamide in this embodiment includes the following steps:

[0100] D1. Add 15 wt% of the GMA grafted modified EMA copolymer prepared in Example 2 to 85 wt% of PA6 and mix evenly to obtain a preliminary mixture.

[0101] D2. Add antioxidants with oxidant type 168 and 1098, EBS and calcium stearate lubricant to the initial mixture described in step D1, mix evenly to obtain a mixture.

[0102] D3. The mixture described in step D2 is added to a twin-screw extruder, and after extrusion, pelleting and drying, the extrusion temperature is 240 ℃ and the drying temperature is 90 ℃ to obtain toughened polyamide.

[0103] Example 8

[0104] This embodiment provides a toughened polyamide comprising 85 wt% of a PA6 matrix and 15 wt% of the GMA-grafted modified EBA copolymer from Example 3.

[0105] The preparation method of the toughened polyamide in this embodiment includes the following steps:

[0106] D1. Add 15 wt% of the GMA grafted modified EBA copolymer prepared in Example 3 to 85 wt% of PA6 and mix evenly to obtain a preliminary mixture.

[0107] D2. Add antioxidants of type 168 and 1098, EBS and calcium stearate lubricant to the initial mixture described in step D1, mix evenly to obtain a mixture.

[0108] D3. The mixture described in step D2 is added to a twin-screw extruder, and after extrusion, pelleting and drying, the extrusion temperature is 240 ℃ and the drying temperature is 90 ℃ to obtain toughened polyamide.

[0109] Example 9

[0110] This embodiment provides a toughened polyamide comprising 85 wt% of a PA6 matrix and 15 wt% of the GMA-grafted modified EBA copolymer from Example 4.

[0111] The preparation method of the toughened polyamide in this embodiment includes the following steps:

[0112] D1. Add 15 wt% of the GMA grafted modified EBA copolymer prepared in Example 4 to 85 wt% of PA6 and mix evenly to obtain a preliminary mixture.

[0113] D2. Add antioxidants of type 168 and 1098, EBS and calcium stearate lubricant to the initial mixture described in step D1, mix evenly to obtain a mixture.

[0114] D3. The mixture described in step D2 is added to a twin-screw extruder, and after extrusion, pelleting and drying, the extrusion temperature is 240 ℃ and the drying temperature is 90 ℃ to obtain toughened polyamide.

[0115] Example 10

[0116] This embodiment provides a toughened polyamide comprising 85 wt% of a polyamide matrix and 15 wt% of the GMA-grafted modified EMA and EBA copolymer from Example 5.

[0117] The preparation method of the toughened polyamide in this embodiment includes the following steps:

[0118] D1. Add 15 wt% of the GMA-grafted modified EMA and EBA copolymer prepared in Example 5 to 85 wt% of PA6 and mix evenly to obtain a preliminary mixture.

[0119] D2. Add antioxidants of type 168 and 1098, EBS and calcium stearate lubricant to the initial mixture described in step D1, mix evenly to obtain a mixture.

[0120] D3. The mixture described in step D2 is added to a twin-screw extruder, and after extrusion, pelleting and drying, the extrusion temperature is 230 ℃ and the drying temperature is 85 ℃ to obtain toughened polyamide.

[0121] Example 11

[0122] This embodiment provides a toughened polyamide comprising 95 wt% of a polyamide matrix and 5 wt% of the GMA-grafted modified EMA and EBA copolymer from Example 7.

[0123] The preparation method of the toughened polyamide in this embodiment includes the following steps:

[0124] D1. Add 5 wt% of the GMA-grafted modified EMA and EBA copolymer prepared in Example 7 to 95 wt% of PA6 and mix evenly to obtain a preliminary mixture.

[0125] D2. Add antioxidants of type 168 and 1098, EBS and calcium stearate lubricant to the initial mixture described in step D1, mix evenly to obtain a mixture.

[0126] D3. The mixture described in step D2 is added to a twin-screw extruder, and after extrusion, pelleting and drying, the extrusion temperature is 230 ℃ and the drying temperature is 85 ℃ to obtain toughened polyamide.

[0127] Example 12

[0128] This embodiment provides a toughened polyamide comprising 90 wt% of a polyamide matrix and 10 wt% of the GMA-grafted modified EMA and EBA copolymer from Example 7.

[0129] The preparation method of the toughened polyamide in this embodiment includes the following steps:

[0130] D1. Add 10 wt% of the GMA-grafted modified EMA and EBA copolymer prepared in Example 7 to 90 wt% of PA6 and mix evenly to obtain a preliminary mixture.

[0131] D2. Add antioxidants of type 168 and 1098, EBS and calcium stearate lubricant to the initial mixture described in step D1, mix evenly to obtain a mixture.

[0132] D3. The mixture described in step D2 is added to a twin-screw extruder, and after extrusion, pelleting and drying, the extrusion temperature is 230 ℃ and the drying temperature is 85 ℃ to obtain toughened polyamide.

[0133] Comparative Example 1

[0134] This comparative example provides a polyamide composed of 100 wt% PA6 without the addition of toughening agents.

[0135] Comparative Example 2

[0136] This comparative example provides a toughened polyamide composed of 85 wt% PA6 and 15 wt% POE-g-MAH toughening agent.

[0137] The polyamides in Examples 6-10 and Comparative Examples 1-2 were subjected to performance tests, and the results are as follows.

[0138] The dried toughened polyamide granules obtained in Examples 6-10, the dried polyamide granules in Comparative Example 1, and the dried toughened polyamide granules in Comparative Example 2 were injection molded on an injection molding machine to prepare test samples. After the test samples were placed for 12 hours, their performance was tested according to the following standards:

[0139] Tensile property testing was conducted according to GB / T1040-1992, with a sample size of 150*10*4 mm and a tensile rate of 50 mm / min.

[0140] Bending performance testing was conducted according to GB / T3356-1996, with a sample size of 80*10*4 mm and a tensile rate of 2 mm / min.

[0141] The notched impact strength test of the cantilever beam was carried out in accordance with GB / T1843-1996. The sample size was 80*10*4 mm and the notch depth was 2 mm.

[0142] Specific performance data is shown in Table 1:

[0143] Table 1 Performance test data of the toughened polyamide in Examples 6-10 and Comparative Example 2 and the polyamide in Comparative Example 1

[0144]

[0145] As shown in Table 1, the elongation at break of the toughened polyamides prepared in Examples 6-10 is generally superior to that of the polyamide in Comparative Example 1; the elongation at break of the toughened polyamides in Examples 6-10 is also significantly superior to that of the polyamides in Comparative Example 1 and Comparative Example 2. The room temperature notched impact strength data shows that the room temperature notched impact strength of the toughened polyamides prepared in Examples 6-10 is significantly higher than that of the polyamides in Comparative Example 1 and Comparative Example 2. The low-temperature notched impact strength (-40 ℃) data shows that, compared to the polyamide using POE-g-MAH toughening agent in Comparative Example 2, the toughened polyamides prepared in Examples 6-10 have a higher low-temperature notched impact strength at -40 ℃, indicating that the toughened polyamide provided by this invention possesses superior toughness at low temperatures. The polyamide in Comparative Example 1 has very poor toughness at -40 ℃, and its low-temperature notched impact strength is very low, so it was not tested. The flexural strength data shows that the flexural strength of the toughened polyamides prepared in Examples 6-10 is generally comparable to that of Comparative Examples 1 and 2. However, the data on elastic modulus and tensile strength show that the toughened polyamides prepared in Examples 6-10, due to the addition of GMA graft-modified copolymer as a toughening agent, have significantly lower elastic modulus and tensile strength than the polyamide in Comparative Example 1. Compared to the polyamide in Comparative Example 2 using POE-g-MAH toughening agent, their overall performance is roughly equivalent. This indicates that the GMA graft-modified copolymer provided by this invention, while ensuring high flexural strength, elastic modulus, and tensile strength of the polyamide, can also significantly improve the elongation at break, room temperature notched impact strength, and low temperature notched impact strength of the polyamide.

[0146] As shown in Table 1, the GMA-grafted modified copolymer provided by this invention can significantly improve the toughness of polyamide. This is because the introduction of GMA functional groups promotes the interfacial compatibility between EMA and / or EBA and PA. In particular, GMA can react with the end groups of PA and bond together, making EMA and / or EBA more compatible with PA, thus making the toughening effect of EMA and / or EBA more obvious. Simultaneously, a comparison reveals that EMA grafted with GMA is more beneficial for improving notched impact strength, while EBA grafted with GMA is more beneficial for improving elongation at break. The compound can combine these two properties. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this invention and are not intended to limit it. Although the invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this invention.

Claims

1. A GMA-grafted modified copolymer, characterized in that, The raw materials include the following parts by weight: 50-95 parts of ethylene-methyl acrylate copolymer and / or ethylene-butyl acrylate copolymer Peroxide initiator 0.1-0.6 parts, 3-5 parts of glycidyl methacrylate 2-5 parts of co-reactant Lubricant 0.5-1 part; The peroxide initiator is at least one of cumene peroxide and 2,5-dimethyl-2,5-di-tert-butylperoxide, the co-reactant is styrene, and the lubricant is methyl silicone oil; The preparation method of the GMA graft-modified copolymer includes the following steps: S1. The mass fractions of glycidyl methacrylate, peroxide initiator, co-reactant and lubricant are premixed to obtain masterbatch; S2. The masterbatch mentioned in step S1 is mixed evenly with the ethylene-methyl acrylate copolymer and / or ethylene-butyl acrylate copolymer in the specified mass fractions and then added to an extruder. The mixture is melt-grafted and extruded at 140-220 °C to obtain the GMA grafted modified copolymer.

2. The GMA graft-modified copolymer according to claim 1, characterized in that, The processing temperatures of the extruder are: Zone 1 140-145 ℃, Zone 2 170-180 ℃, Zone 3 185-190 ℃, Zone 4 190-195 ℃, Zone 5 190-195 ℃, Zone 6 190-195 ℃, and Die head 200-220 ℃.

3. The GMA graft-modified copolymer according to claim 1, characterized in that, The extruder is a twin-screw extruder.

4. A toughened polyamide, characterized in that, It comprises 85-95 wt% of a polyamide matrix and 5-15 wt% of the GMA graft-modified copolymer of claim 1.

5. The toughened polyamide according to claim 4, characterized in that, The polyamide matrix is ​​at least one of PA6 and PA66.

6. The toughened polyamide according to claim 4, characterized in that, The toughened polyamide has an elongation at break of ≥50% at room temperature, and is tested according to GB / T 1040-1992 with a tensile rate of 50 mm / min.

7. The toughened polyamide according to claim 4, characterized in that, The toughened polyamide has a notched impact strength ≥70 kJ / m² at room temperature, and is tested according to GB / T 1843-1996. The sample size is 80×10×4 mm and the notch depth is 2 mm.

8. The toughened polyamide according to claim 4, characterized in that, The toughened polyamide has a low-temperature notched impact strength of ≥28 kJ / m² at -40 ℃, and is tested according to GB / T 1843-1996. The sample size is 80×10×4 mm and the notch depth is 2 mm.

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