A method for preparing micron-sized or submicron-sized filler using polymer material

Abstract

The present invention relates to the technical field of polymer materials, and in particular to a method for preparing micron- or submicron-sized fillers using polymer materials, comprising: immersing the recovered polymer materials in a surfactant and liquid nitrogen in turn, taking them out and rolling them into polymer particles under the action of a press, adding them to a ball mill for primary grinding, immersing the ground polymer particles in deionized water for ultrasonic treatment, adding them to a ball mill for secondary grinding, washing the ground polymer particles with water and then adding them to deionized water to freeze them into solids, sublimating and removing moisture, and obtaining micron- or submicron-sized fillers. The present invention solves the problem of internal molecular chain breakage and degradation caused by remelting of recovered polymer materials in the prior art. The micron- or submicron-sized fillers of the present invention have a narrow particle size distribution, and the size is in the micron or submicron range, which can significantly improve the mechanical properties of the polymer system.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a method for preparing micron-level or submicron-level fillers by using polymer materials. Background Art

[0002] Polymer materials are widely used in industry, agriculture, and transportation. Disposing used plastics as waste is a huge waste of resources and is unsustainable.

[0003] In order to obtain higher mechanical properties, polymer materials often add polymer fillers of other components to the polymer matrix, such as adding plastic to rubber to obtain rubber or plastic products with better performance. Therefore, the quality of the filler has a significant impact on the performance of the composite product. In the prior art, in order to improve resource utilization, recycled polymer particles are generally used as polymer fillers to improve the comprehensive performance of the composite material.

[0004] The existing polymer material recycling technology causes internal molecular chain breakage and degradation due to re-melting processing, which reduces the comprehensive performance of the recycled polymer. This is the main factor limiting the reuse of plastics, rubber, etc. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing micron-level or submicron-level fillers using polymer materials, which is used to solve the problem that the internal molecular chains may be broken and degraded when the polymer materials are recycled and melted again in the prior art. The micron-level or submicron-level fillers of the present invention have a narrow particle size distribution, and the size is in the micron or submicron range, which can significantly increase the mechanical properties of the polymer system.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides a method for preparing a micron-sized or submicron-sized filler using a polymer material, comprising the following steps:

[0007] Step 1: clean the recovered polymer material and cut it into small pieces, immerse it in a surfactant and stir it, take it out and soak it in liquid nitrogen, and then roll it into polymer particles under the action of a press;

[0008] Step 2: Add the polymer particles into a ball mill for grinding, immerse the ground polymer particles in deionized water for ultrasonic treatment, take out and dry to obtain micron-sized polymer particles;

[0009] Step 3: Add the micron-sized polymer particles into a ball mill for secondary grinding, wash the ground polymer particles with water, add them into deionized water and freeze them into a solid, and sublimate to remove water to obtain a micron-sized or submicron-sized filler.

[0010] The polymer material is a recycled material. The above preparation method is used to recycle plastic and prepare it into a micron-level or submicron-level filler, which avoids defects such as molecular chain cracking caused by the remelting of the recycled polymer material during the recycling process. The present invention first selects recyclable plastics or rubbers to avoid thermal degradation caused by the remelting of the polymer during the processing. Secondly, through two grindings, the filler prepared by the recycling process has a narrow particle size distribution, and the particle size is at the micron level or submicron level. The mechanical properties of the composite material using the filler are significantly improved.

[0011] The mechanical properties of polymer products are not only determined by the polymer matrix, but also closely related to the fillers added therein. The type, particle size distribution and particle size of the filler directly affect its dispersibility or distribution in the matrix and determine the interfacial interaction between the polymer matrix. The use of polymer fillers with specific particle size distribution can significantly improve the crystallization properties of the polymer and improve the mechanical properties. The micron- or submicron-grade fillers of the present invention have a narrow particle size distribution and a size of microns or submicrons, which can significantly increase the mechanical properties of the polymer system. The plastic taken out of the liquid nitrogen in step one is quickly crushed into millimeter-sized polymer particles under the action of a press. The smaller the ball diameter in the ball mill, the more conducive it is to prepare smaller-scale plastic particles.

[0012] The water washing in step 3 is beneficial to remove the residual active agent on the surface of the particles and improve the purity of the product; the sublimation time of the freezing system is as long as possible, and the slow sublimation is beneficial to the dispersion of the filler and avoids the agglomeration of the polymer particles.

[0013] In the present invention, micron level refers to 1.0 to 25.0 μm, and submicron level refers to 100 to 1000 nm.

[0014] In one embodiment of the present invention, the difference between the original melt processing temperature and the melting point of the recycled polymer material in step 1 is 10-40° C. The difference between the melt processing temperature and the melting point of the recycled polymer material is 10-40° C., which can minimize the degradation of the molecular chain before recycling and ensure the mechanical properties of the final plastic product.

[0015] In one embodiment of the present invention, the difference between the melt processing temperature and the melting point of the polymer material recovered in step 1 is 10-30°C.

[0016] In one embodiment of the present invention, the specific operation of cutting in step 1 is: cleaning the surface of the recycled polymer material, putting it into ice water and cutting it into small pieces of millimeter size; the polymer particles in step 1 are millimeter size particles. The whole process of cutting the plastic into small pieces is carried out in ice water to avoid the heat generated during the mechanical cutting process affecting the plastic particles.

[0017] In one embodiment of the present invention, the surfactant in step 1 is at least one of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant. The surfactant can ensure that the small-sized polymer particles do not agglomerate during the preparation process, which is beneficial to their dispersion, and the particle size distribution of the polymer particles finally prepared is narrow.

[0018] In one embodiment of the present invention, the small pieces are immersed in liquid nitrogen for ≥3 minutes in step 1. Immersing in liquid nitrogen for ≥3 minutes can ensure that the molecular segments of the small particle plastic are fully frozen, the brittleness of the material increases sharply, and it is conducive to further splitting of the small particle size.

[0019] In one embodiment of the present invention, the specific operation of the one-time grinding in step 2 is: putting the polymer particles and dry ice into a ball mill for grinding to obtain.

[0020] In one embodiment of the present invention, the ultrasonic frequency of the ultrasonic treatment in step 2 is ≥40kHz. The ultrasonic treatment applies ultrasonic impact force to the system, which is beneficial to reducing the size of small plastic particles and making the particle size uniform.

[0021] In one embodiment of the present invention, the grinding time of step 2 and step 3 is ≥ 20 minutes, and the freezing time in step 3 is 1 to 10 minutes. Within this grinding time range, it is beneficial to fully grind the plastic particles and make them uniform in size. Within this freezing time range, it is beneficial to disperse the micron or submicron plastic particles and avoid aggregation.

[0022] In one embodiment of the present invention, the grinding time in step 2 and step 3 is ≥ 30 min, and the freezing time in step 3 is 1 to 5 min.

[0023] As described above, the method of preparing micron-sized or submicron-sized fillers using polymer materials of the present invention has the following beneficial effects: firstly, the present invention selects recyclable plastics or rubbers to avoid thermal degradation caused by remelting of polymers during processing. Secondly, through two grindings, the filler prepared by the recycling process has a narrow particle size distribution, and the particle size is in the micron or submicron level, and the mechanical properties of the composite material using the filler are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the particle size distribution diagram of the filler in Example 1.

[0025] Figure 2 This is the particle size distribution diagram of the filler in Example 5.

[0026] Figure 3 This is a particle size distribution diagram of the filler of Comparative Example 1. DETAILED DESCRIPTION

[0027] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0028] Example 1

[0029] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0030] Step 1: Clean 1 kg of polytetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA) pipe products, the original processing temperature before recycling is 25°C higher than the melting point, remove other impurities, and cut it into millimeter-sized small pieces in ice water.

[0031] Step 2: Immerse the millimeter-sized small pieces in the fatty alcohol polyoxyethylene ether sodium sulfate surfactant and stir evenly. Take out the PFA particles immersed in the fatty alcohol polyoxyethylene ether sodium sulfate surfactant, transfer them to liquid nitrogen for 25 minutes, and then take them out. Immediately put the PFA particles under a 10-ton press and reciprocate to crush them into plastic particles with smaller particle size.

[0032] Step 3: Place the crushed PFA particles in a ball grinder and grind for 40 minutes. Add a small amount of dry ice to the grinder to cool it down. The PFA particles are ground into micrometer-sized particles by the metal ball. The ground polymer particles are immersed in deionized water for ultrasonic treatment (80kHz ultrasonic wave) to obtain micrometer-sized polymer particles.

[0033] Step 4: Replace the metal balls with smaller ball diameters in the grinder to further prepare the micron-sized PFA particles into submicron-sized ones. Wash the powder in deionized water 4 times to remove the fatty alcohol polyoxyethylene ether sodium sulfate surfactant on the PFA powder, freeze the water in the system into a solid state within 5 minutes, slowly sublime the water in the frozen system, collect the PFA powder, and obtain a submicron-sized PFA polymer with a narrow particle size distribution.

[0034] Example 2

[0035] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0036] Step 1: Clean 1 kg of polyvinylidene fluoride (PVDF) film products, the original processing temperature before recycling is 10°C higher than the melting point, remove other impurities, and cut it into small pieces of millimeter size in ice water.

[0037] Step 2: Immerse the millimeter-sized small pieces in the surfactant of non-ionic Gemini fluorocarbon and stir evenly. Take out the PVDF particles immersed in the non-ionic Gemini fluorocarbon, transfer them to liquid nitrogen for 3 minutes, then take them out. Immediately put the PVDF particles under a 10-ton press and reciprocate to crush them into plastic particles with smaller particle size.

[0038] Step 3: Place the crushed PVDF particles in a ball grinder and grind for 30 minutes. Add a small amount of dry ice to the grinder to cool it down. The metal balls grind the particles into micrometer-sized PVDF particles. Immerse the ground polymer particles in deionized water for ultrasonic treatment (90kHz ultrasonic wave) to obtain micrometer-sized polymer particles.

[0039] Step 4: Replace the metal balls with smaller ball diameters in the mill to further prepare the micron-sized PVDF particles into submicron-sized particles. Wash twice in deionized water to remove the non-ionic Gemini fluorocarbon surfactant on the PVDF powder, freeze the water in the system into a solid state within 5 minutes, slowly sublime the water in the frozen system, collect the PVDF powder, and obtain a micron-sized PVDF polymer with a narrow particle size distribution.

[0040] Example 3

[0041] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0042] Step 1: Clean 1 kg of polyetheretherketone (PEEK) injection molded products, the original processing temperature is 20°C higher than the melting point before recycling, remove other impurities, and cut it into millimeter-sized pieces in ice water.

[0043] Step 2: Immerse the millimeter-sized small pieces in anionic fluorocarbon surfactant and stir evenly. Take out the PEEK particles immersed in the anionic fluorocarbon surfactant, transfer them to liquid nitrogen for 30 minutes, and then take them out. Immediately put the PEEK particles under a 10-ton press to reciprocate and roll them into plastic particles with smaller particle size.

[0044] Step 3: Place the crushed PEEK particles in a ball grinder and grind for 40 minutes. Add a small amount of dry ice to the grinder to cool it down, and grind the metal balls to produce micrometer-sized PEEK particles. Immerse the ground polymer particles in deionized water for ultrasonic treatment (40kHz ultrasonic wave) to obtain micrometer-sized polymer particles.

[0045] Step 4: Replace the metal balls with smaller diameters in the grinder to further prepare the micron-sized PEEK particles into submicron-sized particles. Wash the PEEK powder three times in deionized water to remove the anionic fluorocarbon surfactant on the PEEK powder, freeze the water in the system into a solid state within 7 minutes, slowly sublime the water in the frozen system, collect the PEEK powder, and obtain a micron-sized PEEK polymer with a narrow particle size distribution.

[0046] Example 4

[0047] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0048] Step 1: Clean 1 kg of ECTFE injection molded products, the original processing temperature is 30°C higher than the melting point before recycling, remove other impurities, and cut them into small pieces of millimeter size in ice water.

[0049] Step 2: Immerse the millimeter-sized small pieces in sodium dodecylbenzene sulfonate surfactant and stir evenly. Take out the ECTFE particles immersed in the sodium dodecylbenzene sulfonate surfactant, transfer them to liquid nitrogen for 7 minutes, and then take them out. Immediately put the ECTFE particles under a 10-ton press and reciprocate to become plastic particles with smaller particle size.

[0050] Step 3: Place the rolled ECTFE particles in a ball grinder and grind for 35 minutes. Add a small amount of dry ice to the grinder to cool it down. The metal balls grind the ECTFE particles into micrometer-sized particles. Immerse the ground polymer particles in deionized water for ultrasonic treatment (60kHz ultrasonic wave) to obtain micrometer-sized polymer particles.

[0051] Step 4: Replace the metal balls with smaller ball diameters in the grinder to further prepare the micron-level ECTFE particles into submicron-level particles. Wash the ECTFE powder twice in deionized water to remove the sodium dodecylbenzene sulfonate surfactant on the ECTFE powder, freeze the water in the system into a solid state within 4 minutes, slowly sublime the water in the frozen system, collect the ECTFE powder, and obtain a submicron-level ECTFE polymer with a narrow particle size distribution.

[0052] Example 5

[0053] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0054] Step 1: Clean the surface of 1 kg of polyphenylene ether (PPO) plastic products, the original processing temperature before recycling exceeds the melting point by 40°C, remove other impurities, and cut it into small pieces of millimeter size in ice water.

[0055] Step 2: Immerse the millimeter-sized small pieces in a surfactant (alkyl glycoside Glucopon 225DK) and stir evenly. Take out the PPO particles immersed in the surfactant, transfer them to liquid nitrogen for 5 minutes, and then take them out. Immediately place the PPO particles under a 10-ton press and reciprocate to crush them into plastic particles with smaller particle sizes.

[0056] Step 3: Place the crushed PPO particles in a ball grinder and grind for 20 minutes. Add a small amount of dry ice to the grinder to cool it down. The metal balls grind the PPO particles into micrometer-sized particles. Immerse the ground polymer particles in deionized water for ultrasonic treatment (60kHz ultrasonic wave) to obtain micrometer-sized polymer particles.

[0057] Step 4: Wash with deionized water for 3 times to remove the alkyl glycoside Glucopon 225DK surfactant on the PPO powder. Freeze the water in the system into a solid state within 10 minutes, slowly sublime the water in the frozen system, collect the PPO powder, and obtain a micron-sized PPO polymer with a narrow particle size distribution.

[0058] Example 6

[0059] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0060] Step 1: Clean 1 kg of polyamide 66 (PA66) injection molded products, the original processing temperature before recycling is 30°C higher than the melting point, remove other impurities, and cut it into small pieces of millimeter size in water.

[0061] Step 2: Immerse the millimeter-sized small pieces in the ethoxylated sorbitan ester surfactant and stir evenly. Take out the PA66 particles immersed in the ethoxylated sorbitan ester surfactant, transfer them to liquid nitrogen for 5 minutes, and then take them out. Immediately put the PA-66 particles under a 10-ton press to reciprocate and roll them into plastic particles with smaller particle size.

[0062] Step 3: Place the rolled PA66 particles in a ball grinder and grind for 50 minutes. Add a small amount of dry ice to the grinder to cool it down. The PA66 particles are ground into micrometer-sized particles by the metal ball. The ground polymer particles are immersed in deionized water for ultrasonic treatment (50kHz ultrasonic wave) to obtain micrometer-sized polymer particles.

[0063] Step 4: Replace the metal balls with smaller diameters in the grinder to further prepare the micron-sized PA66 particles into submicron-sized particles. Wash twice in deionized water to remove the ethoxylated sorbitan ester surfactant on the PA66 powder, freeze the water in the system into a solid state within 7 minutes, slowly sublime the water in the frozen system, collect the PA66 powder, and obtain a micron-sized PA66 polymer with a narrow particle size distribution.

[0064] Example 7

[0065] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0066] Step 1: Clean 1 kg of polysulfone (PSF) sintered products, the original processing temperature is 15°C higher than the melting point before recycling, remove other impurities, and cut them into small pieces of millimeter size in water.

[0067] Step 2: Immerse the millimeter-sized small pieces in the dehydrated sorbitan ester surfactant and stir evenly. Take out the PSF particles immersed in the dehydrated sorbitan ester surfactant, transfer them to liquid nitrogen for 20 minutes, and then take them out. Immediately put the PSF particles under a 10-ton press and reciprocate to crush them into plastic particles with smaller particle size.

[0068] Step 3: Place the crushed PSF particles in a ball grinder and grind for 60 minutes. Add a small amount of dry ice to the grinder to cool it down. Micron-sized PSF particles are formed under the grinding of metal balls. The ground polymer particles are immersed in deionized water for ultrasonic treatment (50kHz ultrasonic wave) to obtain micron-sized polymer particles.

[0069] Step 4: Replace the metal balls with smaller diameters in the grinder to further prepare the micron-sized PSF particles into submicron-sized ones. Wash the PSF powder in deionized water for 5 times to remove the dehydrated sorbitan ester surfactant on the PSF powder, freeze the water in the system into a solid state within 3 minutes, slowly sublime the water in the frozen system, collect the PSF powder, and obtain a micron-sized PSF polymer with a narrow particle size distribution.

[0070] Comparative Example 1

[0071] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0072] Step 1: Clean 1 kg of polyamide 66 (PA66) injection molded products, the original processing temperature before recycling is 50°C higher than the melting point, remove other impurities, and cut it into small particles in ice water.

[0073] Step 2: Place the PA66 particles under a press and reciprocate to crush them into plastic particles with smaller particle size. Place the crushed PA66 particles in a ball grinder and grind for 10 minutes, collect the PA66 powder, and obtain the PA66 polymer.

[0074] Comparative Example 2

[0075] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0076] Step 1: Clean 1kg of polyvinyl chloride (PVC) pipe products, the original processing temperature before recycling exceeds the melting point by 45°C, remove other impurities, and cut them into small particles in ice water.

[0077] Step 2: Place the PVC particles under a press and reciprocate to crush them into plastic particles with smaller particle sizes. Place the crushed PVC particles in a ball grinder and grind them for 5 minutes, collect the PVC powder, and obtain PVC polymer.

[0078] Comparative Example 3

[0079] A method for preparing a micron-sized or submicron-sized filler using a polymer material comprises the following steps:

[0080] Step 1: Clean 1kg of polypropylene (PP) film, the original processing temperature before recycling exceeds the melting point by 45°C, and remove other impurities. Cut it into small particles in ice water.

[0081] Step 2: Place the PP particles under a press and reciprocate to crush them into plastic particles with smaller particle sizes. Place the crushed PP particles in a ball grinder and grind for 20 minutes, collect the PP powder, and obtain PP polymer.

[0082] The fillers of Examples 1 to 7 and Comparative Examples 1 to 3 were added to NBR and FKM at a mass ratio of 3%, respectively, and their mechanical properties were tested. The specific results are shown in Table 1:

[0083] The tensile strength test is carried out in accordance with the national standard GB / T 1040.1-2006;

[0084] The tear strength test is carried out in accordance with the national standard GB / T 36878-2018;

[0085] Shore A hardness test is carried out in accordance with the national standard GB / T 3398.1-2008.

[0086] Table 1

[0087]

[0088] It can be seen from Table 1 that the mechanical properties of the examples and comparative examples are improved after adding fillers, but the tensile properties of the examples are more improved, the tear strength is stronger, and the hardness is higher.

[0089] Figure 1 , Figure 2 They are the particle size distribution diagrams of the fillers in Example 1 and Example 5 respectively; Figure 3 is the particle size distribution diagram of the filler in Comparative Example 1. Figure 1 , 2 and Figure 3 By comparison, it can be seen that the particle size distribution of Example 1 is narrow, while the particle size distribution of Comparative Example 1 is wide, the particle size is large, and the specific surface area is small. In summary, the product prepared by the recycling technology of the present invention is stable, and the performance of the rubber product after adding as a filler is more excellent.

[0090] In summary, the present invention firstly selects recyclable plastics or rubbers, and avoids thermal degradation caused by remelting of polymers during processing. Secondly, through two grindings, the filler particle size distribution prepared by the recycling process is narrow, and the particle size is in the micron or submicron level, and the mechanical properties of the composite material using the filler are significantly improved. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0091] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing micron-sized or submicron-sized fillers using polymer materials, characterized in that: The steps include: Step 1, cleaning the recovered polymer material and cutting it into small pieces, then immersing it in a surfactant and stirring it, taking it out and soaking it in liquid nitrogen, and then rolling it into polymer particles under the action of a press; the difference between the melt processing temperature and the melting point of the recovered polymer material is 10-40° C.; the polymer particles are millimeter-sized particles; the specific operation of the cutting is: cleaning the surface of the recovered polymer material, putting it in ice water and cutting it into millimeter-sized small pieces; Step 2: Add the polymer particles into a ball mill for grinding, immerse the ground polymer particles in deionized water for ultrasonic treatment, and obtain micron-sized polymer particles; Step 3: Add micron-sized polymer particles into a ball mill for secondary grinding, wash the ground polymer particles with water, add them into deionized water and freeze them into a solid, sublimate to remove water, and obtain micron-sized or submicron-sized fillers; the freezing time is 1 to 10 minutes.

2. The method for preparing micron-sized or submicron-sized fillers using polymer materials according to claim 1, characterized in that: The difference between the melt processing temperature and the melting point of the polymer material recovered in step 1 is 10 to 30°C.

3. A method for preparing micron-sized or submicron-sized fillers using polymer materials according to any one of claims 1 to 2, characterized in that: The surfactant in step 1 is at least one of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant.

4. A method for preparing micron-sized or submicron-sized fillers using polymer materials according to any one of claims 1 to 2, characterized in that: In the step 1, the small pieces are immersed in liquid nitrogen for ≥3 minutes.

5. The method for preparing micron-sized or submicron-sized fillers using polymer materials according to claim 1, characterized in that: The specific operation of the first grinding in step 2 is: putting the polymer particles and dry ice into a ball mill for grinding to obtain.

6. The method for preparing micron-sized or submicron-sized fillers by using polymer materials according to claim 1 or 5, characterized in that: The ultrasonic frequency of the ultrasonic treatment in step 2 is ≥40 kHz.

7. The method for preparing micron-sized or submicron-sized fillers using polymer materials according to claim 1, characterized in that: The grinding time of step 2 and step 3 is both ≥ 20 min.

8. The method for preparing micron-sized or submicron-sized fillers by using polymer materials according to claim 1 or 7, characterized in that: The grinding time in step 2 and step 3 is both ≥30 min, and the freezing time in step 3 is 1 to 5 min.

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