Polymer composite material based on boron nitride and production process thereof

Abstract

The invention relates to the technical field of materials, and discloses a boron nitride-based polymer composite material and a production process thereof, the polymer composite material is prepared by using high density polyethylene as a base material and modified boron nitride and the like as auxiliary materials through blending and extrusion processes, wherein the modified boron nitride is prepared by modifying a functional polymerization modifier on the surface of boron nitride, and a molecular chain of the functional polymerization modifier can extend to each region of a polyethylene molecular matrix in a melting process, so that a tenon-and-mortise-like embedded structure is formed at an interface; boron nitride can effectively play a role as an inorganic reinforcing agent, the mechanical strength of polyethylene is effectively improved, a hindered phenol antioxidant structure is contained in the functional polymerization modifier structure, a good modification effect on the antioxidant performance of polyethylene can be achieved, in addition, uniformly dispersed boron nitride can form a heat conduction network, and the heat conduction performance of polyethylene is improved. Therefore, the heat stability of the polyethylene is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a boron nitride-based polymer composite material and a production process thereof. Background Art

[0002] Polyethylene is a thermoplastic with the characteristics of low density and light weight, which makes it easy to process and transport. Moreover, polyethylene has excellent low-temperature resistance, with the lowest operating temperature reaching -100°C to -70°C. It also has good chemical stability, high transparency, superior waterproof performance and excellent electrical insulation. It is currently widely used in all walks of life.

[0003] With the continuous development of science and technology, the performance requirements for polymer products are becoming higher and higher. Although the comprehensive performance of polyethylene in all aspects is acceptable, it is gradually unable to meet the application needs of special industries. In particular, polyethylene has poor thermal stability and is easy to soften at high temperatures. In addition, thermal oxidative aging is prone to occur when used in high temperature environments, which greatly shortens the service life of the product. This is a huge obstacle to the further application of polyethylene plastic products. Therefore, how to improve the high temperature resistance and antioxidant properties of polyethylene has become a research hotspot at this stage.

[0004] At present, it is common to modify polyethylene by using additives, such as small molecule antioxidants, etc. However, small molecule antioxidants themselves are easy to volatilize and migrate, and it is difficult for them to exist continuously in the polyethylene matrix, which leads to the fact that the long-term antioxidant effect of polyethylene cannot be guaranteed. In addition, there are also methods of adding inorganic fillers to improve the mechanical strength of polyethylene, etc. However, there is a serious interface repulsion effect between the inorganic filler and the polyethylene matrix, which makes it difficult to disperse evenly. When the addition amount is large, it will also have a negative impact on the performance of the polyethylene. Therefore, the present invention provides a polyethylene-based polymer composite material, which can solve the problems existing in the prior art. Summary of the invention

[0005] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a boron nitride-based polymer composite material and a production process thereof.

[0006] (II) Technical solution A production process of a polymer composite material based on boron nitride, the polymer composite material comprising the following raw materials in parts by weight: High density polyethylene 55-65 parts; 25-35 parts of low density polyethylene; Compatibilizer 5-15 parts; Modified boron nitride 2-4.5 parts; 0.5-1.5 parts of UV absorber; 1-2 parts of lubricant; The production process comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight. Step 2: Add the prepared high-density polyethylene, low-density polyethylene, compatibilizer, modified boron nitride, ultraviolet absorber and lubricant into the mixer, control the temperature to 80-100°C, the stirring rate to 600-800r / min, stir and mix for 20-40min, cool and discharge to form a premix; The third step is to feed the premix into a twin-screw extruder through a feed port, and then undergo a melt extrusion process to obtain a polymer composite material.

[0007] As a further embodiment of the present invention, the compatibilizer is maleic anhydride grafted polyethylene or at least one of maleic anhydride grafted polyethylene.

[0008] As a further embodiment of the present invention, the preparation method of the modified boron nitride comprises the following steps: Step S1, dispersing hydroxylated boron nitride in toluene, then adding anhydride to the formed uniform dispersion, raising the temperature to 90-100°C, adding p-toluenesulfonic acid, stirring for 2-4 hours, cooling and discharging, separating the solid material, and obtaining a boron nitride modified intermediate material; Step S2, adding the boron nitride modified intermediate material and the composite catalyst into tetrahydrofuran, and after uniform ultrasonic dispersion, continuing stirring for 1-2 hours, and then adding the functional polymerization modifier, stirring at room temperature for 4-8 hours after the addition is complete, cooling and discharging the material, and the modified boron nitride can be obtained.

[0009] As a further embodiment of the present invention, in step S1, the acid anhydride substance is any one of maleic anhydride, succinic anhydride or glutaric anhydride.

[0010] As a further embodiment of the present invention, in step S1, the preparation method of the hydroxylated boron nitride is: Hexagonal boron nitride is added to hydrogen peroxide with a mass fraction of 30%, and treated at an ultrasonic frequency of 80-100kHz for 10-30 minutes, and then the temperature is controlled to 80-90°C, and the mixture is stirred for 6-12 hours. The heating is stopped, the temperature is lowered, and the material is discharged to obtain hydroxylated boron nitride.

[0011] As a further solution of the present invention, in step S2, the composite catalyst is dicyclohexylcarbodiimide and 4-dimethylaminopyridine, and the mass ratio is 1:0.1-0.3.

[0012] As a further solution of the present invention, in step S2, the specific preparation method of the functional polymerization modifier comprises the following steps: Step SS1, adding 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidol to toluene, starting stirring, and after a uniform mixed solution is formed, adding a phase transfer catalyst to the mixed solution, after the addition is completed, starting heating, maintaining the temperature at 70-80° C., keeping the temperature for 2-4 hours, evaporating to remove the solvent, cooling the material, collecting the product, and obtaining a hindered phenol intermediate; Step SS2, add the hindered phenol intermediate to N,N-dimethylformamide, stir to mix, continue to add sodium hydroxide aqueous solution, after adding, stir at 50-60°C for 2-4h, continue to add 2,7-dibromo-9,9-dimethylfluorene, and increase the temperature to 90-100°C, keep warm for 8-12h, and the functional polymerization modifier can be obtained.

[0013] As a further embodiment of the present invention, in step SS1, the phase transfer catalyst is any one of tetrabutylammonium bromide, tetrabutylammonium hydrogen sulfate or tetramethylammonium chloride.

[0014] As a further embodiment of the present invention, in step SS2, the molar ratio of the hindered phenol intermediate to 2,7-dibromo-9,9-dimethylfluorene is 1:0.8-1.

[0015] Specifically, firstly, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidol are used as raw materials. Under the action of a phase transfer catalyst, the active carboxyl substituent and the epoxy substituent can undergo a ring-opening esterification reaction to obtain a hindered phenol intermediate containing two equivalents of active hydroxyl substituents in the structure. Then, sodium hydroxide is used as an activator to activate the hydroxyl groups in the structure. Then, 2,7-dibromo-9,9-dimethylfluorene is used as a bridging agent to carry out continuous substitution reactions to form a macromolecular substance with a block connection structure, namely a functional polymerization modifier. By controlling the dosage ratio of the two, the functional polymerization modifier can have a hydroxyl-terminated structure.

[0016] The surface of hydroxylated boron nitride is modified by using anhydride substances to obtain boron nitride with active carboxyl functional groups on the surface, thereby obtaining a boron nitride modified intermediate material. Then, under the action of a composite catalyst, the capped hydroxyl groups in the structure of the functional polymerization modifier can be further esterified and condensed with the carboxyl groups of the boron nitride modified intermediate material, thereby modifying the functional polymerization modifier on the surface of the boron nitride to obtain a modified boron nitride.

[0017] A boron nitride-based polymer composite material is prepared by adopting the above production process.

[0018] 3. Beneficial technical effects The present invention prepares modified boron nitride by modifying the surface of boron nitride with a functional polymer modifier, and uses the modified boron nitride as an additive to modify a polyethylene matrix. Firstly, the presence of the functional polymer modifier can form a transition connection layer at the interface between the boron nitride and the polyethylene matrix, and the transition structure can greatly improve the interface bonding performance between each other, avoiding the problem of negative impact caused by the boron nitride agglomeration problem. Secondly, the molecular chain of the functional polymer modifier can extend to various regions of the polyethylene molecular matrix during the melting process, and then form a "mortise and tenon" type mosaic structure at the interface, so that the boron nitride can efficiently exert its effect as an inorganic reinforcing agent and effectively improve the mechanical strength of polyethylene.

[0019] In addition, since the functional polymerization modifier contains a block-linked hindered phenol antioxidant structure, it can have a good modification effect on the antioxidant properties of polyethylene, and due to the mutual entanglement between the molecular chains, the hindered phenol antioxidant structure will not migrate, which can ensure the long-term antioxidant effect of polyethylene. In addition, the functional polymerization modifier structure also contains a rigid heterocyclic structure, which can improve the stability of polyethylene and improve its thermal stability. In addition, the uniformly dispersed boron nitride can form a heat-conducting network to dissipate heat, thereby further improving the thermal stability of polyethylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0021] Figure 1 This is the infrared analysis test diagram of the functional polymerization modifier. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. Preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0023] Preparation Example 1.

[0024] Preparation of modified boron nitride: Step S1, adding hexagonal boron nitride to hydrogen peroxide with a mass fraction of 30%, treating at an ultrasonic frequency of 100 kHz for 20 minutes, then controlling the temperature to 90°C, keeping the temperature and stirring for 9 hours, stopping heating, cooling and discharging, and obtaining hydroxylated boron nitride; Step S2, dispersing 1.5 g of hydroxylated boron nitride in toluene, and then adding 3.4 g of succinic anhydride to the formed uniform dispersion. After the addition, the temperature is raised to 100° C., and 0.1 g of p-toluenesulfonic acid is added. After stirring for 3 hours, the temperature is lowered and the material is discharged. The solid material is separated to obtain a boron nitride modified intermediate material; Step S3, add 1.2g of boron nitride modified intermediate material, 0.5g of dicyclohexylcarbodiimide, and 0.1g of 4-dimethylaminopyridine to tetrahydrofuran, and after ultrasonic dispersion, continue stirring for 1h, and then add 1.5g of functional polymerization modifier. After the addition is complete, stir at room temperature for 6h, cool and discharge the material to obtain modified boron nitride.

[0025] The specific preparation method of the functional polymerization modifier is as follows: Step SS1, adding 0.4 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and 0.1 g of glycidol to toluene, stirring, and after a uniform mixed solution is formed, 0.02 g of tetrabutylammonium bromide is added to the mixed solution. After the addition is completed, heating is started and the temperature is maintained at 756° C. After keeping the temperature for 3 hours, the solvent is evaporated and removed, the temperature is lowered and the material is discharged, and the product is collected to obtain a hindered phenol intermediate; Step SS2, add 0.6 g of hindered phenol intermediate to N,N-dimethylformamide, stir to mix, continue to add 10 mL of 20% sodium hydroxide aqueous solution, after adding, stir at 60 ° C for 3 h, continue to add 0.5 g of 2,7-dibromo-9,9-dimethylfluorene, and increase the temperature to 90 ° C., keep warm for 9 h, and you can get a functional polymerization modifier.

[0026] Figure 1 This is the infrared analysis test chart of the functional polymerization modifier, where 3302cm -1 The characteristic absorption peak at 3000cm is the characteristic absorption peak of hydroxyl group. -1 ~3100cm -1 The characteristic absorption peak at 2800cm is the characteristic absorption peak of carbon and hydrogen in benzene ring. -1 ~3000cm -1 The characteristic absorption peaks appearing at 1748cm are the characteristic absorption peaks of carbon and hydrogen in methyl and methylene. -1 The characteristic absorption peak at 1100 cm is the direct C=O characteristic absorption peak produced by the ring-opening esterification reaction. -1 The characteristic absorption peak appearing at is the characteristic absorption peak of the ether bond produced by the substitution reaction.

[0027] Example 1. A boron nitride-based polymer composite material comprises the following raw materials in parts by weight: 55 parts of high density polyethylene; 25 parts of low density polyethylene; 5 parts of maleic anhydride grafted polyethylene; 2 parts of modified boron nitride; 0.5 parts of UV absorber; 1 part lubricant; The production process of the polymer composite material comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight. Step 2: Add the prepared high-density polyethylene, low-density polyethylene, maleic anhydride grafted polyethylene, modified boron nitride, ultraviolet absorber and lubricant into a mixer, control the temperature to 80°C, the stirring rate to 600r / min, stir and mix for 40 minutes, cool and discharge the materials to form a premix; The third step is to feed the premix into the twin-screw extruder through the feeding port, control the temperature of each zone of the extruder to 200°C, 210°C, 220°C, 220°C, 210°C, 210°C, and the screw speed to 50rpm, and obtain the polymer composite material through the melt extrusion process.

[0028] The preparation method of the modified boron nitride is shown in Preparation Example 1; UV-234 is selected as the ultraviolet absorber; polyethylene wax is selected as the lubricant, and the rest are the same.

[0029] Example 2. A boron nitride-based polymer composite material comprises the following raw materials in parts by weight: High density polyethylene 60 parts; 30 parts of low density polyethylene; Maleic anhydride grafted polyethylene 8 parts; 4 parts of modified boron nitride; 1 part of UV absorber; 1.5 parts of lubricant; The production process of the polymer composite material comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight. Step 2: Add the prepared high-density polyethylene, low-density polyethylene, maleic anhydride grafted polyethylene, modified boron nitride, ultraviolet absorber and lubricant into a mixer, control the temperature to 100°C, the stirring rate to 600r / min, stir and mix for 30 minutes, cool and discharge the materials to form a premix; The third step is to feed the premix into the twin-screw extruder through the feeding port, control the temperature of each zone of the extruder to 200°C, 210°C, 220°C, 220°C, 210°C, 210°C, and the screw speed to 50rpm, and obtain the polymer composite material through the melt extrusion process.

[0030] Example 3. A boron nitride-based polymer composite material comprises the following raw materials in parts by weight: 65 parts of high density polyethylene; 35 parts of low density polyethylene; 15 parts of maleic anhydride grafted polyethylene; 4.5 parts of modified boron nitride; 1.5 parts of UV absorber; 2 parts of lubricant; The production process of the polymer composite material comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight. Step 2: Add the prepared high-density polyethylene, low-density polyethylene, maleic anhydride grafted polyethylene, modified boron nitride, ultraviolet absorber and lubricant into a mixer, control the temperature to 100°C, the stirring rate to 800r / min, stir and mix for 20 minutes, cool and discharge the materials to form a premix; The third step is to feed the premix into the twin-screw extruder through the feeding port, control the temperature of each zone of the extruder to 200°C, 210°C, 220°C, 220°C, 210°C, 210°C, and the screw speed to 50rpm, and obtain the polymer composite material through the melt extrusion process.

[0031] Comparative Example 1. A boron nitride-based polymer composite material, comprising the following raw materials in parts by weight: High density polyethylene 60 parts; 30 parts of low density polyethylene; Maleic anhydride grafted polyethylene 8 parts; 4 parts of hexagonal boron nitride; 1 part of UV absorber; 1.5 parts of lubricant; The production process of the polymer composite material comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight. Step 2: Add the prepared high-density polyethylene, low-density polyethylene, maleic anhydride grafted polyethylene, hexagonal boron nitride, ultraviolet absorber and lubricant into a mixer, control the temperature to 100°C, the stirring rate to 600r / min, stir and mix for 30 minutes, cool and discharge the materials to form a premix; The third step is to feed the premix into the twin-screw extruder through the feeding port, control the temperature of each zone of the extruder to 200°C, 210°C, 220°C, 220°C, 210°C, 210°C, and the screw speed to 50rpm, and obtain the polymer composite material through the melt extrusion process.

[0032] Comparative Example 2. A boron nitride-based polymer composite material, comprising the following raw materials in parts by weight: High density polyethylene 60 parts; 30 parts of low density polyethylene; Maleic anhydride grafted polyethylene 8 parts; 4 parts of functional polymer modifier; 1 part of UV absorber; 1.5 parts of lubricant; The production process of the polymer composite material comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight. Step 2: Add the prepared high-density polyethylene, low-density polyethylene, maleic anhydride grafted polyethylene, functional polymerization modifier, ultraviolet absorber and lubricant into a mixer, control the temperature to 100°C, the stirring rate to 600r / min, stir and mix for 30 minutes, cool and discharge the materials to form a premix; The third step is to feed the premix into the twin-screw extruder through the feeding port, control the temperature of each zone of the extruder to 200°C, 210°C, 220°C, 220°C, 210°C, 210°C, and the screw speed to 50rpm, and obtain the polymer composite material through the melt extrusion process.

[0033] Comparative Example 3. A boron nitride-based polymer composite material, comprising the following raw materials in parts by weight: High density polyethylene 60 parts; 30 parts of low density polyethylene; Maleic anhydride grafted polyethylene 8 parts; 1 part of UV absorber; 1.5 parts of lubricant; The production process of the polymer composite material comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight. Step 2: Add the prepared high-density polyethylene, low-density polyethylene, maleic anhydride grafted polyethylene, ultraviolet absorber and lubricant into a mixer, control the temperature to 100°C, the stirring rate to 600r / min, stir and mix for 30 minutes, cool and discharge the materials to form a premix; The third step is to feed the premix into the twin-screw extruder through the feeding port, control the temperature of each zone of the extruder to 200°C, 210°C, 220°C, 220°C, 210°C, 210°C, and the screw speed to 50rpm, and obtain the polymer composite material through the melt extrusion process.

[0034] Test Example: The polymer composite materials in the examples and comparative examples were made into test samples that met the specifications, and various performance tests were performed. The results are recorded in the following table:

[0035] The tensile strength test refers to the standard GB / T 1040.1-2018. The samples of the same batch are subjected to tensile strength test under normal conditions and recorded as the initial value. Then the samples are placed in an oven at 150°C for accelerated aging test. After 12 hours, the samples are taken out and the tensile strength is tested. The value is recorded as the post-treatment value. The antioxidant properties of the samples are evaluated by the difference between the two. Generally speaking, the smaller the difference, the better the antioxidant properties, and vice versa.

[0036] The thermal decomposition temperature test method is: place the sample in an oven, set the heating rate to 5°C / min, increase the temperature from room temperature to 500°C, and the temperature when the sample loses 5% of its weight is the initial decomposition temperature.

[0037] Based on the ideal embodiment of the present invention, through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A production process of a polymer composite material based on boron nitride, characterized in that: The polymer composite material comprises the following raw materials in parts by weight: High density polyethylene 55-65 parts; 25-35 parts of low density polyethylene; Compatibilizer 5-15 parts; Modified boron nitride 2-4.5 parts; 0.5-1.5 parts of UV absorber; 1-2 parts of lubricant; The production process comprises the following steps: The first step is to weigh and prepare all the raw materials according to their weight. Step 2: Add the prepared high-density polyethylene, low-density polyethylene, compatibilizer, modified boron nitride, ultraviolet absorber and lubricant into the mixer, control the temperature to 80-100°C, the stirring rate to 600-800r / min, stir and mix for 20-40min, cool and discharge to form a premix; The third step is to feed the premix into a twin-screw extruder through a feed port, and then undergo a melt extrusion process to obtain a polymer composite material.

2. The production process of a boron nitride-based polymer composite material according to claim 1, characterized in that: The compatibilizer is at least one of maleic anhydride grafted polyethylene or maleic anhydride grafted polyethylene.

3. The production process of a boron nitride-based polymer composite material according to claim 1, characterized in that: The preparation method of the modified boron nitride comprises the following steps: Step S1, using anhydride substances to perform surface modification on hydroxylated boron nitride to obtain a boron nitride modified intermediate material; Step S2: using a composite catalyst to catalyze a further grafting reaction between the functional polymerization modifier and the boron nitride modified intermediate material, thereby obtaining modified boron nitride.

4. The production process of a boron nitride-based polymer composite material according to claim 3, characterized in that: In step S1, the acid anhydride substance is any one of maleic anhydride, succinic anhydride or glutaric anhydride.

5. The production process of a boron nitride-based polymer composite material according to claim 3, characterized in that: In step S1, the preparation method of the hydroxylated boron nitride is: Hexagonal boron nitride is added to hydrogen peroxide with a mass fraction of 30%, and treated at an ultrasonic frequency of 80-100kHz for 10-30 minutes, and then the temperature is controlled to 80-90°C, and the mixture is stirred for 6-12 hours. The heating is stopped, the temperature is lowered, and the material is discharged to obtain hydroxylated boron nitride.

6. The production process of a boron nitride-based polymer composite material according to claim 3, characterized in that: In step S2, the composite catalyst is dicyclohexylcarbodiimide and 4-dimethylaminopyridine, and the mass ratio is 1:0.1-0.

3.

7. The production process of a boron nitride-based polymer composite material according to claim 3, characterized in that: In step S2, the specific preparation method of the functional polymerization modifier comprises the following steps: Step SS1, adding 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidol to toluene, starting stirring, and after a uniform mixed solution is formed, adding a phase transfer catalyst to the mixed solution, after the addition is completed, starting heating, maintaining the temperature at 70-80° C., keeping the temperature for 2-4 hours, evaporating to remove the solvent, cooling the material, collecting the product, and obtaining a hindered phenol intermediate; Step SS2, add the hindered phenol intermediate to N,N-dimethylformamide, stir to mix, continue to add sodium hydroxide aqueous solution, after adding, stir at 50-60°C for 2-4h, continue to add 2,7-dibromo-9,9-dimethylfluorene, and increase the temperature to 90-100°C, keep warm for 8-12h, and the functional polymerization modifier can be obtained.

8. The production process of a boron nitride-based polymer composite material according to claim 7, characterized in that: In step SS1, the phase transfer catalyst is any one of tetrabutylammonium bromide, tetrabutylammonium hydrogen sulfate or tetramethylammonium chloride.

9. The production process of a boron nitride-based polymer composite material according to claim 7, characterized in that: In step SS2, the molar ratio of the hindered phenol intermediate to 2,7-dibromo-9,9-dimethylfluorene is 1:0.8-1.

10. A polymer composite material based on boron nitride, characterized in that: The method is prepared by the production process according to any one of claims 1 to 9.

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