Preparation method and application of high-toughness and high-barrier PA6 / MXD6 / POK alloy material

Abstract

The invention discloses a preparation method and application of a PA6 / MXD6 / POK alloy material with high toughness and high barrier properties, belonging to the technical field of polymer materials. The preparation method comprises the following steps: mixing a molten state of caprolactam with a polyketone resin, adding sodium hydride to reduce the carbonyl group on the polyketone to generate a hydroxyl group, adding an isocyanate activator, and removing water after the reaction to obtain component A; mixing a poly(m-phenylenediamine adipamide) resin with a molten state of caprolactam, adding a catalyst after removing water, and mixing evenly to obtain component B. Component A and component B are extruded by an extruder, cooled, and granulated to obtain a PA6 / MXD6 / POK alloy material. The hydroxyl group of the polyketone resin molecular chain after reduction reacts with the isocyanate to form a macromolecular activator, and a copolymer is generated during the reaction extrusion process, thereby improving the compatibility of POK and PA6, and realizing continuous production of the alloy material. The excellent toughness and barrier properties of the alloy material broaden the application of the material in the fields of automobile fuel tanks, cooling pipelines, and packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and specifically relates to a preparation method and application of a high-toughness and high-barrier PA6 / MXD6 / POK alloy material. Background Art

[0002] With the rapid development of my country's economy, the new energy automobile industry has also ushered in a peak period, and automobile materials are required to develop towards lightweight, multifunctional and intelligent trends. Lightweight development requires replacing steel with plastic and increasing the proportion of composite materials used in automobiles. Nylon (PA) is one of the most widely used engineering plastics at present, with advantages such as high melting point, good wear resistance and fatigue resistance, but nylon materials generally have disadvantages such as low modulus and poor impact performance.

[0003] Polyketone (POK) resin is a new type of green and environmentally friendly thermoplastic engineering plastic developed by South Korea's Hyosung Corporation. It uses carbon monoxide, ethylene and propylene as main raw materials and has low water absorption, high wear resistance, high chemical resistance, high impact strength and high gas barrier properties. Its impact toughness is 2.5 times that of PA6 and its oil resistance is 2 times that of PA12. It is almost the most balanced engineering material at present and has a very broad application prospect, but its processing temperature range is relatively narrow and the cost is relatively high.

[0004] There are some reports on PA / POK alloys, which are modified by melt blending. Chinese patents with application numbers 201711161472.5, 202011131652.0 and 202211254212.3 all disclose methods for preparing PA6 / POK alloys by blending, which modify the alloys in terms of reinforcement, flame retardancy, hydrolysis resistance and wear resistance. However, there are the following problems: (1) POK has low thermal stability and is easily oxidized and decomposed during the blending process; (2) The compatibility of PA6 and POK leads to the dispersion of POK in the matrix, which directly affects the overall performance of the alloy.

[0005] Poly(m-phenylenediamine adipamide) (MXD6) has excellent barrier properties, and the barrier properties are independent of humidity. After being added to PA6, it can not only improve the barrier properties, but also has good compatibility with PA6 and improves its mechanical properties. However, conventional PA-based composite materials are usually prepared by direct melt extrusion using PA pellets. Reactive extrusion uses the extruder as a continuous reactor to polymerize monomers or cause chemical reactions between polymers and additives to achieve the purpose of polymer modification or incompatible system capacity expansion. There are not many reports on the preparation of PA-based composite materials by lactam anion ring-opening polymerization in an extruder. Therefore, the study of the preparation of in-situ polymerized PA composite materials by reactive extrusion will be a meaningful work. Summary of the invention

[0006] The object of the present invention is to provide a preparation method and application of a high-toughness and high-barrier PA6 / MXD6 / POK alloy material. The PA6 / MXD6 / POK alloy material is continuously prepared by reactive extrusion technology. The preparation process is simple, and the alloy material has high toughness and high barrier properties.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] The present invention provides a method for preparing a high-toughness and high-barrier PA6 / MXD6 / POK alloy material, comprising the following steps:

[0009] Step 1, dissolving polyketone resin in molten caprolactam under mechanical stirring at 120-160°C, adding sodium hydride to carry out chemical reaction after mixing evenly, reducing the carbonyl group on the polyketone to generate hydroxyl group, adding isocyanate activator to react with the hydroxyl group on the polyketone resin molecular chain to generate macromolecular activator POK-g-NCO, and removing water to obtain component A;

[0010] Step 2, dissolving poly(m-xylylene adipamide) resin in molten caprolactam, adding a catalyst after removing water, and mixing evenly to obtain component B;

[0011] Step 3, add component A and component B into a liquid feeding tank respectively, add them into the feeding section of the extruder through a metering pump, pass through a compression section and a metering section, extrude them by a screw, and undergo cooling, cutting and granulation to obtain a PA6 / MXD6 / POK alloy material;

[0012] The reaction equation for reducing the carbonyl group on the polyketone to generate the hydroxyl group is as follows:

[0013]

[0014] or ;

[0015] The reaction equation for generating the macromolecular activator POK-g-NCO is as follows (taking the reaction of A with 2,4-toluene diisocyanate as an example):

[0016] ,

[0017] Among them, m=200-1000, n=500-2000.

[0018] Furthermore, in step three, the temperature of the feeding section of the extruder is 90-120°C, the temperature of the compression section is 140-200°C, the temperature of the metering section is 200-240°C, the temperature of the extruder head is 220-240°C, and the screw speed is 50-300r / min.

[0019] Further, the polyketone resin is one of a carbon monoxide-ethylene binary copolymer and a carbon monoxide-ethylene-propylene terpolymer;

[0020] The amount of propylene in the carbon monoxide-ethylene-propylene terpolymer is less than twice the amount of ethylene.

[0021] Furthermore, the isocyanate activator is at least one of 2,4-toluene diisocyanate, diphenylmethane diisocyanate and isophorone diisocyanate.

[0022] Furthermore, the relative viscosity of the poly(meta-xylylene adipamide) resin is >2.

[0023] Furthermore, the catalyst is at least one of an alkali metal hydroxide and sodium caprolactam.

[0024] Furthermore, the component A comprises the following raw materials in parts by mass: 100 parts of caprolactam, 5-50 parts of polyketone resin, 0.01-10 parts of isocyanate activator and 0.5-10 parts of sodium hydride.

[0025] Furthermore, the component B comprises the following raw materials by mass: 100 parts of caprolactam, 1-20 parts of poly(m-xylylene adipamide) resin and 0.1-10 parts of catalyst.

[0026] Furthermore, in step three, component A and component B are added to the feeding section of the reaction extruder according to a mass ratio of 1-10:1.

[0027] The present invention also provides an application of a PA6 / MXD6 / POK alloy material with high toughness and high barrier properties. The PA6 / MXD6 / POK alloy material prepared by the above-mentioned preparation method can be used in automobile fuel tanks, cooling pipelines and packaging fields.

[0028] Beneficial effects of the present invention:

[0029] (1) The present invention adopts an in-situ polymerization-reaction extrusion process, which has the characteristics of high efficiency and low cost, and can realize the continuous production of PA6 / MXD6 / POK alloy materials.

[0030] (2) The present invention reduces the carbonyl groups in the molecular chain of the polyketone resin to hydroxyl groups, reacts with isocyanate to form a macromolecular activator, and generates a copolymer during the reaction extrusion process, thereby improving the compatibility of POK and PA6, enhancing their interfacial effect, and achieving uniform dispersion of POK in PA6 monomer without adding a compatibilizer.

[0031] (3) Due to the good compatibility of MXD6, POK and PA6, the alloy material is endowed with good strength and toughness, lower water absorption and higher chemical resistance, wear resistance and barrier properties, which broadens the application of this material in automotive fuel tanks, cooling pipes and packaging fields. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0034] Polyketone resins, such as M930A, M330A and M630A produced by Hyosung Group of Korea, are selected, and the viscosity of the resin increases in sequence;

[0035] Caprolactam, industrial grade, manufactured by China Eastern Chemical Industry Group Co., Ltd.

[0036] Catalyst: analytical grade sodium caprolactam, manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd.; analytical grade potassium hydroxide, manufactured by Sinopharm Chemical Reagent Co., Ltd.;

[0037] Activator, 2,4-toluene diisocyanate (TDI), analytical grade, manufacturer Shanghai Aladdin Biochemical Technology Co., Ltd.; isophorone diisocyanate (IPDI), analytical grade, manufacturer Wanhua Chemical Group Co., Ltd.; diphenylmethane diisocyanate (MDI), analytical grade, manufacturer Guangdong Wengjiang Chemical Reagent Co., Ltd. All materials are commercially available conventional products.

[0038] Example 1

[0039] Step 1: Place 100 parts of caprolactam into a 2L three-necked flask and heat to melt, heat to 120°C, add 10 parts of polyketone resin M930A under mechanical stirring, stir and mix evenly, then add 0.5 parts of sodium hydride to react for 1 hour, add 0.5 parts of 2,4-toluene diisocyanate dropwise, react for 2 hours under stirring to generate a macromolecular activator POK-g-NCO, remove water in vacuo, and obtain component A.

[0040] Step 2: Place 100 parts of caprolactam in a 2L three-necked flask and heat to melt, heat to 140°C, add 1 part of poly(m-phenylenediamine adipamide) resin under mechanical stirring, stir and mix evenly, remove water in vacuo, add 1 part of sodium caprolactam catalyst and mix evenly to obtain component B.

[0041] Step 3, add component A and component B into the extruder feeding tank respectively, start the extruder, and use the metering pump to let component A and component B enter the feeding section of the extruder in a mass ratio of 1:1. After the compression section and the metering section, the reaction extrusion is carried out under the shearing action of the screw. After the extrudate is cooled in a cold water bath, it is sent to a cutting machine for cutting and granulation to obtain a PA6 / MXD6 / POK alloy material, wherein the feeding section temperature is 90-120°C, the compression section temperature is 140-200°C, the metering section temperature is 200-240°C, the reaction extruder head temperature is 220-240°C, and the screw speed is 300r / min.

[0042] Example 2

[0043] The difference from Example 1 is that in step 1, the temperature is heated to 140° C., the number of parts of the polyketone resin M930A is adjusted to 15 parts, and the other conditions and steps are the same as in Example 1.

[0044] Example 3

[0045] The difference from Example 1 is that in step 1, the temperature is heated to 140° C., the number of parts of the polyketone resin M930A is adjusted to 20 parts, and the other conditions and steps are the same as in Example 1.

[0046] Example 4

[0047] The difference from Example 3 is that the amount of 2,4-toluene diisocyanate in step 1 is adjusted to 0.8 parts, and the other conditions and steps are the same as Example 3.

[0048] Example 5

[0049] The difference from Example 3 is that the amount of 2,4-toluene diisocyanate in step 1 is adjusted to 1.0 part, and the other conditions and steps are the same as Example 3.

[0050] Example 6

[0051] The difference from Example 4 is that the number of parts of the poly(meta-xylylene adipamide) resin in step 2 is adjusted to 2 parts, and the other conditions and steps are the same as those in Example 4.

[0052] Example 7

[0053] The difference from Example 4 is that the number of parts of the poly(meta-xylylene adipamide) resin in step 2 is adjusted to 5 parts, and the other conditions and steps are the same as those in Example 4.

[0054] Example 8

[0055] The difference from Example 7 is that in step 1, the polyketone resin M930A is replaced by the polyketone resin M330A, and the 2,4-toluene diisocyanate is replaced by isophorone diisocyanate. Other conditions and steps are the same as in Example 1.

[0056] Example 9

[0057] The difference from Example 7 is that in step 1, the temperature is heated to 160° C., the polyketone resin M930A is replaced by the polyketone resin M630A, and the 2,4-toluene diisocyanate is replaced by diphenylmethane diisocyanate. Other conditions and steps are the same as in Example 1.

[0058] Comparative Example 1

[0059] Compared with Example 1, the alloy material of this comparative example is prepared by blending PA6 resin, polyketone resin and poly(m-xylylene adipamide) resin, and the specific steps are as follows.

[0060] Step 1: Place 100 parts of PA6 resin into a 2L three-necked flask and heat to melt, heat to 120°C, add 10 parts of polyketone resin M930A under mechanical stirring, stir and mix evenly, and remove water in vacuo to obtain component A.

[0061] Step 2: Place 100 parts of PA6 resin into a 2L three-necked flask and heat to melt, heat to 140°C, add 1 part of poly(m-phenylenediamine adipamide) resin under mechanical stirring, stir and mix evenly, and remove water in vacuo to obtain component B.

[0062] Step 3, add component A and component B into the extruder feeding tank respectively, start the extruder, and use the metering pump to let component A and component B enter the feeding section of the extruder in a mass ratio of 1:1. After the compression section and the metering section, the reaction extrusion is carried out under the shearing action of the screw. After the extrudate is cooled in a cold water bath, it is sent to a cutting machine for cutting and granulation to obtain a PA6 / MXD6 / POK alloy material, wherein the feeding section temperature is 90-120°C, the compression section temperature is 140-200°C, the metering section temperature is 200-240°C, the reaction extruder head temperature is 220-240°C, and the screw speed is 300r / min.

[0063] Mechanical test: The pellets of PA6 / MXD6 / POK alloy material obtained in the embodiment and comparative example were injection molded into mechanical property test specimens using a plastic injection machine. The tensile property test reference standard was GB / T 1040, the bending property test reference standard was GB / T9341, and the notched impact test reference standard was GB / T 1843. Five specimens were tested for each type of specimen, and the average value was taken as the result of the group.

[0064] Barrier property test: The obtained PA6 / MXD6 / POK alloy material pellets were prepared into films by injection molding and stretching. The films were respectively pasted in the mouths of bottles filled with xylene and strictly sealed. After equilibrium at 25°C and relative humidity of 50%, the amount of xylene permeated was measured every 24 hours under standard atmospheric pressure. The permeation amount was plotted against time. The slope of the straight line was the average mass change. The permeability coefficient was calculated according to the following formula:

[0065] P = QD / AT,

[0066] Where P is the permeability coefficient, unit is g·m / (m 2 / atm / 24hr); Q is the mass reduced in a given time, g; D is the thickness of the film, m; A is the area of ​​the bottle mouth, m 2 ; T is the measurement time interval, 24h.

[0067] The oxygen transmission rate was measured using an oxygen transmission rate tester from Guangzhou Biaoji Packaging Equipment Co., Ltd. Model Y310. The test principle of the coulometric oxygen sensor was followed in accordance with GB / T 19789 standard. The unit is cm 3 / (cm 2 ·24h·0.1MPa).

[0068] Performance tests were performed on Examples 1 to 9 and Comparative Example 1. The results are shown in Table 1:

[0069] Table 1

[0070]

[0071] As can be seen from Table 1, the proportion of polyketone resin in the alloy material is gradually increased in Examples 1 to 3, and an appropriate amount of polyketone resin can react with the activator to form a macromolecular activator, promote compatibility, and improve performance. The toughness and barrier properties of the alloy material in Example 2 are significantly better than those in Example 1. Excessive polyketone resin in Example 3 leads to poor compatibility and decreased performance. Examples 4 and 5 increase the amount of isocyanate on the basis of Example 3, and the compatibility of the materials is improved, and the overall performance is improved. On the basis of Example 4, Examples 6 and 7 increase the proportion of MXD6, and the performance of the alloy material is further improved. In Comparative Example 1, PA6 resin is directly used to prepare the alloy material. At this time, the polyketone resin cannot react with the activator to generate the macromolecular activator POK-g-NCO. The compatibility of the material is far inferior to that of Example 1, and various properties are poor.

[0072] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0073] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-toughness and high-barrier PA6 / MXD6 / POK alloy material, characterized in that: The following steps are involved: Step 1, dissolving polyketone resin in molten caprolactam under mechanical stirring at 120-160°C, adding sodium hydride to carry out chemical reaction after mixing evenly, reducing the carbonyl group on the polyketone to generate hydroxyl group, adding isocyanate activator to react with the hydroxyl group on the polyketone resin molecular chain to generate macromolecular activator POK-g-NCO, and removing water to obtain component A; Step 2, dissolving poly(m-xylylene adipamide) resin in molten caprolactam, adding a catalyst after removing water, and mixing evenly to obtain component B; Step 3, add component A and component B into a liquid feeding tank respectively, add them into the feeding section of the extruder through a metering pump, pass through a compression section and a metering section, extrude them by a screw, and undergo cooling, cutting and granulation to obtain a PA6 / MXD6 / POK alloy material; The component A comprises the following raw materials by weight: 100 parts of caprolactam, 10-20 parts of polyketone resin, 0.5-1.0 parts of isocyanate activator and 0.5-20 parts of sodium hydride; The component B comprises the following raw materials by weight: 100 parts of caprolactam, 1-5 parts of poly(m-xylylene adipamide) resin and 0.1-1.0 parts of catalyst; In step three, the component A and the component B are added to the feeding section of the reaction extruder according to a mass ratio of 1-10:

1.

2. The method for preparing a high-toughness and high-barrier PA6 / MXD6 / POK alloy material according to claim 1, characterized in that: In step 3, the temperature of the feeding section of the extruder is 90-120°C, the temperature of the compression section is 140-200°C, the temperature of the metering section is 200-240°C, the temperature of the extruder head is 220-240°C, and the speed of the screw is 50-300r / min.

3. The method for preparing a high-toughness and high-barrier PA6 / MXD6 / POK alloy material according to claim 1, characterized in that: The polyketone resin is one of a carbon monoxide-ethylene binary copolymer and a carbon monoxide-ethylene-propylene ternary copolymer; The amount of propylene in the carbon monoxide-ethylene-propylene terpolymer is less than twice the amount of ethylene.

4. The method for preparing a high-toughness and high-barrier PA6 / MXD6 / POK alloy material according to claim 1, characterized in that: The isocyanate activator is at least one of 2,4-toluene diisocyanate, diphenylmethane diisocyanate and isophorone diisocyanate.

5. The method for preparing a high-toughness and high-barrier PA6 / MXD6 / POK alloy material according to claim 1, characterized in that: The relative viscosity of the poly(m-xylylene adipamide) resin is>2.

6. The method for preparing a high-toughness and high-barrier PA6 / MXD6 / POK alloy material according to claim 1, characterized in that: The catalyst is at least one of an alkali metal hydroxide and sodium caprolactam.

7. An application of a high-toughness and high-barrier PA6 / MXD6 / POK alloy material, characterized in that: The PA6 / MXD6 / POK alloy material prepared by the preparation method according to any one of claims 1 to 6 is used in the fields of automobile fuel tanks, cooling pipelines and packaging.

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