Preparation method of high-wear-resistance PP composite material for stationery

Abstract

The invention discloses a preparation method of a high-wear-resistance PP composite material for stationery, the configuration of core-shell-shell composite particles is designed, a coating layer can provide protection, keep the particles complete and avoid early leakage of a core layer during processing, the binding force between the coating layer and a PP component is strong, the falling phenomenon of the composite particles can be reduced, and the wear resistance of the composite particles is improved. In addition, the coating layer is also beneficial to promoting the composite particles to migrate to the surface layer of the material, the wear resistance is better improved, the coating layer is synchronously released when the shearing force is large, a shear-heat dual response mechanism is constructed under the cooperation, and the ionic liquid and the latent curing agent are in contact with moisture in air after being released to polymerize to form a repairing film layer. The addition of the composite particles helps to improve the wear resistance of the pp material.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a method for preparing high abrasion-resistant PP composite materials for stationery. Background Technology

[0002] Stationery is a common tool for students, such as pencil cases, stationery boxes, and ballpoint pens. Common stationery materials include PP material. However, PP material has slightly poor wear resistance. Stationery is prone to obvious wear marks after long-term use or vigorous friction, which affects its appearance and does not meet the performance requirements of high-end stationery on the market.

[0003] To address the above issues, common solutions include adding inorganic wear-resistant particles. However, the amount of these particles added is relatively large, which can easily affect other properties of the PP material and requires improvement. Summary of the Invention

[0004] To address at least one of the aforementioned technical deficiencies, the present invention provides the following technical solution:

[0005] This application discloses a method for preparing a high abrasion-resistant PP composite material for stationery, including the following steps: First, the preparation of core-shell composite particles. The core is covered by a shell, the shell is covered by a coating layer, the core is an ionic liquid and a latent curing agent, the shell is polyethylene wax, and the coating layer is ethylene-vinyl acetate copolymer. Second, the core-shell composite particles are mixed with PP components and additives to prepare a molded composite material.

[0006] Furthermore, the preparation steps of the shell-coated core are as follows: ionic liquid, latent curing agent and PE-g-MAH are mixed and sheared and stirred at high speed at 60-70℃ for at least 30 min to form a core precursor. Hydrophobic nano-silica is dispersed in polyethylene wax solution to form a mother liquor. The core precursor is added dropwise to the mother liquor and sheared at high speed at 100-110℃ for 10-15 min to form microdroplets. Then, molten polyethylene wax is mixed with microdroplets and sheared and stirred, extruded, granulated underwater and cryogenically pulverized to obtain shell-coated core composite particles.

[0007] Furthermore, the mass ratio of the ionic liquid to the latent curing agent is 8:2-3, the hydrophobic nano-silica is 0.3-0.8% of the mass of the ionic liquid, and the mass ratio of the polyethylene wax to the ionic liquid and the latent curing agent is 6:3-4.

[0008] Furthermore, the preparation steps of coating the shell layer are as follows: the core-type composite particles are modified with a silane coupling agent to obtain modified particles, the modified particles are added to a shear mixer and preheated to 60-70°C, EVA resin is melted and sprayed onto the high-speed rotating core composite particle layer through an atomizing nozzle, heating is stopped and cooling is performed so that EVA is solidified on the core composite particles to form a coating layer, and the core-shell-coated composite particles are obtained by sieving.

[0009] Furthermore, zinc stearate at a mass of 0.1% is added when the EVA resin is melted, and the mass ratio of EVA resin to core-type composite particles is 3-2:5.

[0010] Furthermore, in the second step, the PP components and additives are mixed and injection molded. The injection molding parameters are as follows: mold-fixed mold: 60-80℃, mold-moving mold: 20-30℃, front section: 225-235℃, middle section: 210-220℃, rear section: 190-200℃, nozzle: 230-240℃, injection speed: 40-60mm / s, holding pressure: 40-60MPa, and holding time: 3-5s.

[0011] Furthermore, the additives are a mixture of PP-g-MAH, nucleating agent, and antioxidant. By mass, PP-g-MAH accounts for 0.3-0.8% of the composite material, the nucleating agent accounts for 0.1-0.2% of the composite material, and the antioxidant accounts for 0.2-0.3% of the composite material.

[0012] Furthermore, by mass, the core-shell composite particles account for 0.6-3% of the composite material.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention designs a core-shell-coated composite particle configuration, wherein the coating layer provides protection during processing, maintaining particle integrity and preventing premature leakage of the core layer. Furthermore, the coating layer has strong adhesion to the PP component, reducing particle detachment. Additionally, the coating layer helps promote particle migration to the material surface, improving wear resistance. The shell layer is low-melting-point; when stationery friction exceeds its melting point, the shell softens or melts to open a channel for core release. Simultaneously, the coating layer is released under high shear stress, creating a shear-thermal dual response mechanism. After release, the ionic liquid and latent curing agent contact moisture in the air to polymerize and form a repair film. The addition of these composite particles helps improve the wear resistance of PP materials.

[0014] 2. The present invention defines the composition of additives in composite materials, wherein nucleating agents, interface modifiers such as PP-g-MAH help to promote the migration of composite particles to the surface of the material, thereby improving wear resistance with a small amount of doping.

[0015] 3. The process parameters of the material are limited by the present invention. High injection speed, holding pressure and mold temperature help to promote the migration of composite particles to the surface of the material. Detailed Implementation

[0016] The present invention will be further described below with reference to specific embodiments.

[0017] materials: PP component: Sinopec K8003; Ionic liquid: hydrophobic imidazole, [bmim]PF6; Latent curing agent: Aldehydeimide; Polyethylene wax: melting point 130-138℃, acid value 15-17, viscosity 8100-9000, Jiaxing Zhongcheng Environmental Protection Technology Co., Ltd., model 316A; Ethylene-vinyl acetate copolymer (EVA): Merck, CAS No.: 437247; Nucleating agent: β-type nucleating agent, WBG-II; Antioxidant: Type 1010; Hydrophobic nano-silica: CAS No.: 68611-44-9.

[0018] Example 1 A method for preparing high abrasion-resistant PP composite material for stationery includes the following steps: First, the preparation of core-shell composite particles. The core is covered by a shell, the shell is covered by a coating layer, the core is an ionic liquid and a latent curing agent, the shell is polyethylene wax, and the coating layer is ethylene-vinyl acetate copolymer. The specific steps are as follows: The preparation steps of the core with shell coating are as follows: the above ionic liquid, latent curing agent and PE-g-MAH are mixed and stirred at high speed (2100 rpm) at 65°C for 35 min to form the core precursor. The mass ratio of ionic liquid, latent curing agent and PE-g-MAH is 8:2:0.5.

[0019] Hydrophobic nano-silica (mass ratio of 100:0.5 to ionic liquid) was dispersed in polyethylene wax solution (1 / 20 of the total mass of ionic liquid and latent curing agent) to form a mother liquor. The core precursor was added dropwise to the mother liquor and sheared at high speed (6000 rpm) at 105℃ for 10 min to form microdroplets. Then, molten polyethylene wax (mass ratio of 3:2 to ionic liquid and latent curing agent) was mixed with the microdroplets and sheared and stirred (1500 rpm) for 10 min. After that, it was extruded and granulated underwater (cutter speed 2000 rpm). Particles of 350-450 μm were obtained by sieving. The sieved particles were then subjected to cryogenic pulverization (pre-cooling temperature -120℃, time 6 min, pulverization chamber temperature -90±3℃, rotor linear speed 65 m / s) to obtain shell-coated core-type composite particles with a particle size in the range of 50-200 μm.

[0020] The preparation steps of coating the shell layer are as follows: The core-type composite particles prepared above are modified with silane coupling agent (KH560, sprayed, accounting for 0.6% of the total mass of the core-type composite particles) to obtain modified particles. The modified particles are added to a shear mixer (1000 rpm) and stirred and preheated to 65°C. EVA resin (in a ratio of 2:5 to the total mass of the core-type composite particles) is melted and sprayed onto the high-speed rotating core composite particle layer through an atomizing nozzle. After spraying, heating is stopped and cold air is introduced to cool so that EVA is cured on the core composite particles to form a coating layer. The core-shell-coated composite particles (particle size in the range of 50-200 μm) are obtained by sieving.

[0021] When EVA resin is melted, zinc stearate is added at a rate of 0.1% of its mass.

[0022] Second, the PP component and additives are mixed and injection molded. By mass, the core-shell composite particles account for 0.8% of the composite material. The additives are a mixture of PP-g-MAH, nucleating agent, and antioxidant. By mass, PP-g-MAH accounts for 0.3% of the composite material, the nucleating agent accounts for 0.1% of the composite material, the antioxidant accounts for 0.3% of the composite material, and the remainder is the PP component.

[0023] The injection molding parameters are as follows: mold - fixed mold: 65℃, mold - moving mold: 25℃, front section: 230℃, middle section: 212℃, rear section: 195℃, nozzle: 230℃, injection speed: 50mm / s, holding pressure: 52MPa, holding time: 4s.

[0024] Example 2 A method for preparing high abrasion-resistant PP composite material for stationery includes the following steps: First, the preparation of core-shell composite particles. The core is covered by a shell, the shell is covered by a coating layer, the core is an ionic liquid and a latent curing agent, the shell is polyethylene wax, and the coating layer is ethylene-vinyl acetate copolymer. The specific steps are as follows: The preparation steps of the core with shell coating are as follows: ionic liquid, latent curing agent and PE-g-MAH are mixed and stirred at high speed (2100 rpm) at 65℃ for 35 min to form core precursor. The mass ratio of ionic liquid, latent curing agent and PE-g-MAH is 8:3:0.6.

[0025] Hydrophobic nano-silica (mass ratio of 100:0.6 to ionic liquid) was dispersed in polyethylene wax solution (1 / 20 of the total mass of ionic liquid and latent curing agent) to form a mother liquor. The core precursor was added dropwise to the mother liquor and sheared at high speed (6000 rpm) at 105℃ for 10 min to form microdroplets. Then, molten polyethylene wax (mass ratio of 3:2 to ionic liquid and latent curing agent) was mixed with the microdroplets and sheared and stirred (1500 rpm) for 10 min. After that, it was extruded and granulated underwater (cutter speed 2000 rpm). Particles of 350-450 μm were obtained by sieving. The sieved particles were then subjected to cryogenic pulverization (pre-cooling temperature -120℃, time 6 min, pulverization chamber temperature -90±3℃, rotor linear speed 65 m / s) to obtain shell-coated core composite particles with a particle size in the range of 50-200 μm.

[0026] The preparation steps of the coating layer are as follows: The core-type composite particles prepared above are modified with silane coupling agent (KH560, sprayed, accounting for 0.6% of the total mass of the core-type composite particles) to obtain modified particles. The modified particles are added to a shear mixer (1000 rpm) and stirred and preheated to 65°C. EVA resin (in a ratio of 2.2:5 to the total mass of the core-type composite particles) is melted and sprayed onto the high-speed rotating core composite particle layer through an atomizing nozzle. After spraying, heating is stopped and cold air is introduced to cool so that EVA is cured on the core composite particles to form a coating layer. The core-shell coating composite particles (particle size in the range of 50-200 μm) are obtained by sieving.

[0027] Zinc stearate at a mass of 0.2% is added when EVA resin is melted.

[0028] Second, the PP component and additives are mixed and injection molded. By mass, the core-shell composite particles account for 0.8% of the composite material. The additives are a mixture of PP-g-MAH, nucleating agent, and antioxidant. By mass, PP-g-MAH accounts for 0.4% of the composite material, the nucleating agent accounts for 0.2% of the composite material, the antioxidant accounts for 0.5% of the composite material, and the remainder is the PP component.

[0029] The injection molding parameters are as follows: mold - fixed mold: 65℃, mold - moving mold: 25℃, front section: 230℃, middle section: 212℃, rear section: 195℃, nozzle: 230℃, injection speed: 50mm / s, holding pressure: 52MPa, holding time: 4s.

[0030] Example 3 A method for preparing high abrasion-resistant PP composite material for stationery includes the following steps: First, the preparation of core-shell composite particles. The core is covered by a shell, the shell is covered by a coating layer, the core is an ionic liquid and a latent curing agent, the shell is polyethylene wax, and the coating layer is ethylene-vinyl acetate copolymer. The specific steps are as follows: The preparation steps of the core with shell coating are as follows: ionic liquid, latent curing agent and PE-g-MAH are mixed and stirred at high speed (2100 rpm) at 65℃ for 35 min to form core precursor. The mass ratio of ionic liquid, latent curing agent and PE-g-MAH is 8:2:0.5.

[0031] Hydrophobic nano-silica (mass ratio of 100:0.5 to ionic liquid) was dispersed in polyethylene wax solution (1 / 20 of the total mass of ionic liquid and latent curing agent) to form a mother liquor. The core precursor was added dropwise to the mother liquor and sheared at high speed (6000 rpm) for 10 min at 100-110℃ to form microdroplets. Then, molten polyethylene wax (mass ratio of 3:2 to ionic liquid and latent curing agent) was mixed with the microdroplets and sheared and stirred (1500 rpm) for 10 min. After that, it was extruded and granulated underwater (cutter speed 2000 rpm). Particles of 350-450 μm were obtained by sieving. The sieved particles were then subjected to cryogenic pulverization (pre-cooling temperature -120℃, time 6 min, pulverization chamber temperature -90±3℃, rotor linear speed 65 m / s) to obtain shell-coated core composite particles with a particle size in the range of 50-200 μm.

[0032] The preparation steps of the coating layer are as follows: The core-type composite particles prepared above are modified with silane coupling agent (KH560, sprayed, accounting for 0.6% of the total mass of the core-type composite particles) to obtain modified particles. The modified particles are added to a shear mixer (1000 rpm) and stirred and preheated to 65°C. EVA resin (in a ratio of 3:5 to the total mass of the core-type composite particles) is melted and sprayed through an atomizing nozzle onto the high-speed rotating core composite particle layer. After spraying, heating is stopped and cold air is introduced to cool so that EVA is cured on the core composite particles to form a coating layer. The core-shell coating composite particles (particle size in the range of 50-200 μm) are obtained by sieving.

[0033] Zinc stearate at a mass of 0.3% is added when EVA resin is melted.

[0034] Second, the PP component and additives are mixed and injection molded. By mass, the core-shell composite particles account for 1.5% of the composite material. The additives are a mixture of PP-g-MAH, nucleating agent, and antioxidant. By mass, PP-g-MAH accounts for 0.5% of the composite material, the nucleating agent accounts for 0.3% of the composite material, the antioxidant accounts for 0.4% of the composite material, and the remainder is the PP component.

[0035] The injection molding parameters are as follows: mold - fixed mold: 65℃, mold - moving mold: 25℃, front section: 230℃, middle section: 212℃, rear section: 195℃, nozzle: 230℃, injection speed: 55mm / s, holding pressure: 55MPa, holding time: 4s.

[0036] The wear resistance of the PP composite material prepared above was tested under normal atmospheric pressure, with a load of 200 N and a time of 1 hour. The wear amount is as follows: Table 1

[0037] As shown in Table 1, the PP composite material prepared above exhibits excellent wear resistance. Furthermore, cross-sectional analysis reveals that nearly 40% of the core-shell composite particles are located in the surface region, confirming surface migration. Additionally, our company tested the coefficient of friction of the PP composite material prepared in Example 1. From 0-5 min, the coefficient of friction was 0.35-0.45, primarily due to friction from the PP matrix. From 5-20 min, the coefficient of friction was 0.20-0.25, due to the release of ionic liquid and polyethylene wax from the ruptured core-shell structure, forming a lubricating film.

[0038] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing high abrasion-resistant PP composite material for stationery, characterized in that, Includes the following steps: First, the preparation of core-shell composite particles. The core is covered by a shell, the shell is covered by a coating layer, the core is an ionic liquid and a latent curing agent, the shell is polyethylene wax, and the coating layer is ethylene-vinyl acetate copolymer. Second, the core-shell composite particles are mixed with PP components and additives to prepare a molded composite material.

2. The preparation method of the high abrasion-resistant PP composite material for stationery as described in claim 1, characterized in that: The preparation steps of the shell-coated core are as follows: ionic liquid, latent curing agent and PE-g-MAH are mixed and sheared and stirred at high speed at 60-70℃ for at least 30 min to form a core precursor. Hydrophobic nano-silica is dispersed in polyethylene wax solution to form mother liquor. The core precursor is added dropwise to the mother liquor and sheared at high speed at 100-110℃ for 10-15 min to form microdroplets. Then the molten polyethylene wax is mixed with the microdroplets and sheared and stirred, extruded, granulated underwater and cryogenically pulverized to obtain shell-coated core composite particles.

3. The method for preparing high abrasion-resistant PP composite material for stationery as described in claim 2, characterized in that: The mass ratio of the ionic liquid to the latent curing agent is 8:2-3, the hydrophobic nano-silica is 0.3-0.8% of the mass of the ionic liquid, and the ratio of the polyethylene wax to the ionic liquid and the latent curing agent is 6:3-4.

4. The method for preparing the high abrasion-resistant PP composite material for stationery as described in claim 2, characterized in that: The preparation steps of coating the shell are as follows: the core-type composite particles are modified with silane coupling agent to obtain modified particles, the modified particles are added to a shear mixer and preheated to 60-70℃, EVA resin is melted and sprayed onto the high-speed rotating core composite particle layer through an atomizing nozzle, heating is stopped and cooling is performed so that EVA is solidified on the core composite particles to form a coating layer, and the core-shell-coated composite particles are obtained by sieving.

5. The method for preparing the high abrasion-resistant PP composite material for stationery as described in claim 1, characterized in that: When EVA resin is melted, zinc stearate is added at a mass ratio of 0.1% of its mass. The mass ratio of EVA resin to core-type composite particles is 3-2:

5.

6. The method for preparing the high abrasion-resistant PP composite material for stationery as described in claim 1, characterized in that: In the second step, the PP components and additives are mixed and injection molded. The injection molding parameters are as follows: mold-fixed mold: 60-80℃, mold-moving mold: 20-30℃, front section: 225-235℃, middle section: 210-220℃, rear section: 190-200℃, nozzle: 230-240℃, injection speed: 40-60mm / s, holding pressure: 40-60MPa, and holding time: 3-5s.

7. The method for preparing the high abrasion-resistant PP composite material for stationery as described in claim 6, characterized in that: The additives are a mixture of PP-g-MAH, nucleating agent, and antioxidant. By mass, PP-g-MAH accounts for 0.3-0.8% of the composite material, the nucleating agent accounts for 0.1-0.2% of the composite material, and the antioxidant accounts for 0.2-0.3% of the composite material.

8. The method for preparing the high abrasion-resistant PP composite material for stationery as described in claim 1, characterized in that: By mass, the core-shell composite particles account for 0.6-3% of the composite material.

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