A preparation method of green and environmentally friendly PP plastic

Abstract

The invention relates to the technical field of polypropylene composite materials, and discloses a method for preparing green and environmentally friendly PP plastic. The invention uses ethylenediamine as a crosslinking agent, crosslinks epoxysiloxane polyacrylate and ethylenediamine to form a wall material of a microcapsule through a crosslinking reaction of an amino group and an epoxy group, realizes in-situ coating of ammonium polyphosphate, obtains polyacrylate-coated ammonium polyphosphate microcapsules, and uses sisal fiber oxidized by potassium permanganate as a biomass environmentally friendly modifier to perform blending modification on polypropylene, thereby improving the mechanical strength of polypropylene. Meanwhile, sisal fiber, as a natural biomass green and environmentally friendly resource, is non-toxic and pollution-free, and is compounded with polypropylene to obtain a green and environmentally friendly composite material, thereby further enhancing the green and environmentally friendly effect of the polypropylene composite material while enhancing the performance of the polypropylene material.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene composite materials, in particular to a method for preparing green and environmentally friendly PP plastic. Background Art

[0002] In recent years, as people's environmental awareness continues to improve, the use of non-degradable petroleum-based polymer materials such as polypropylene and polystyrene is gradually being reduced; currently, countries around the world are vigorously developing green and environmentally friendly materials. By compounding plastics such as polypropylene with natural bio-based materials such as wood powder and cellulose, green and environmentally friendly wood-plastic composite materials with excellent performance can be obtained.

[0003] Although polypropylene (PP) plastic has the advantages of low density, light weight, good processing performance, and excellent electrical insulation, it has poor mechanical strength and is easy to burn, which is not conducive to the application of polypropylene plastic in flame retardant and fireproof materials; ammonium polyphosphate is a common flame retardant, widely used in plastics, fibers and other fields; ammonium polyphosphate has poor resistance to moisture and heat, easily absorbs moisture to form agglomerates, and has poor compatibility with materials such as polypropylene. When the addition amount is too large, it will have a great impact on the mechanical strength of the material.

[0004] As a natural biomass resource, sisal fiber has good mechanical strength, toughness and wear resistance. It can be used as a filler and compounded with polymers such as polypropylene to improve the performance of polypropylene plastics. Therefore, the interface compatibility between sisal fiber and polypropylene is required. The main modification methods include coupling agent modification, acidification modification, oxidation modification and other methods. Summary of the invention

[0005] Technical problem solved: Provides a green and environmentally friendly method for preparing PP plastic, solving the problem of low strength and poor flame retardancy of PP plastic.

[0006] Technical solution:

[0007] A green and environmentally friendly PP plastic comprises the following raw materials: 100 parts by weight of polypropylene, 15-60 parts by weight of potassium permanganate oxidized sisal fiber, and 10-35 parts by weight of polyacrylate-coated ammonium polyphosphate microcapsules; the preparation method of the green and environmentally friendly PP plastic is as follows:

[0008] Step S1, adding epoxysiloxane polyacrylate to N,N-dimethylformamide, stirring and dispersing, adding ammonium polyphosphate and cross-linking agent ethylenediamine, reflux reaction at 55-65° C. for 6-12 hours, filtering, washing with water, and drying to obtain polyacrylate-coated ammonium polyphosphate microcapsules.

[0009] Step S2, adding polypropylene, potassium permanganate oxidized sisal fiber, and polyacrylate-coated ammonium polyphosphate microcapsules into an open mill, mixing at 180-200° C. for 5-10 min, and then heat-maintaining and pressure-maintaining treatment at 190-200° C. for 5-10 min in a flat vulcanizer at a pressure of 10-15 MPa to obtain green and environmentally friendly PP plastic.

[0010] Wherein, the mass of epoxysiloxane polyacrylate and ethylenediamine in step S1 are 15-35% and 8-15% of ammonium polyphosphate respectively.

[0011] Wherein, the preparation method of epoxysiloxane polyacrylate is as follows:

[0012] Step (1), add 100 parts by weight of 3-chloro-2-hydroxypropyl methacrylate and 70-88 parts by weight of pyridine to toluene, add 65-80 parts by weight of trimethylchlorosilane dropwise in a nitrogen atmosphere, react at 30-45° C. for 6-12 hours, concentrate under reduced pressure, wash with petroleum ether, and obtain a siloxane acrylate intermediate.

[0013] Step (2), adding the siloxane acrylate intermediate to tetrahydrofuran, adding sodium hydride and tetrabutylammonium bromide under an ice-water bath, reacting at 25-35° C. for 8-18 hours, adding water after the reaction, concentrating under reduced pressure to remove tetrahydrofuran, then adding ethyl acetate, shaking and extracting, concentrating the ethyl acetate organic phase to obtain an epoxy siloxane acrylate monomer.

[0014] Step (3), adding epoxysiloxane acrylate monomer to N,N-dimethylformamide, adding azobisisobutyronitrile dropwise in a nitrogen atmosphere, reacting at 55-70° C. for 3-6 hours, cooling, pouring the solution into ethanol to precipitate, filtering, washing with ethanol, and drying to obtain epoxysiloxane polyacrylate.

[0015] Wherein, the masses of sodium hydride and tetrabutylammonium bromide in step (2) are 22-30% and 2-3% of the siloxane acrylate intermediate respectively.

[0016] Wherein, the mass of azobisisobutyronitrile in step (3) is 0.8-1.3% of the epoxysiloxane acrylate monomer.

[0017] Technical effect: The present invention uses 3-chloro-2-hydroxypropyl methacrylate, trimethylchlorosilane, glycidol and the like as reactants, and prepares a novel epoxysiloxane acrylate monomer through siloxane and substitution reactions, and obtains epoxysiloxane polyacrylate through polymerization reactions.

[0018] The invention uses epoxysilicone polyacrylate as a wall material, ammonium polyphosphate as a capsule material, and ethylenediamine as a crosslinking agent. Through the crosslinking reaction of amino groups and epoxy groups, the epoxysilicone polyacrylate and ethylenediamine are crosslinked to form the wall material of the microcapsule, thereby realizing in-situ coating of the ammonium polyphosphate and obtaining the polyacrylate-coated ammonium polyphosphate microcapsules.

[0019] The present invention uses polyacrylate-coated ammonium polyphosphate microcapsules as flame retardants and potassium permanganate-oxidized sisal fibers as biomass green and environmentally friendly modifiers to perform blending modification on polypropylene. After the ammonium polyphosphate is coated with the polyacrylate wall material, its solubility in water is greatly reduced, and its water absorption rate and water absorption rate are reduced, which is conducive to overcoming the problem that the ammonium polyphosphate has poor moisture and heat resistance and is easy to absorb water and moisture and agglomerate. It avoids affecting the mechanical properties of the polypropylene matrix. Moreover, as a natural biomass green and environmentally friendly resource, sisal fibers are non-toxic and pollution-free. After being compounded with polypropylene, a green and environmentally friendly wood-plastic composite material can be obtained. While strengthening the performance of the polypropylene material, the green and environmentally friendly effect of the polypropylene composite material is further enhanced.

[0020] The polyacrylate-coated ammonium polyphosphate microcapsules of the present invention have good compatibility with polypropylene, so that the microcapsules coated with ammonium polyphosphate have excellent dispersibility in polypropylene PP plastics, avoiding the addition of microcapsules or the addition of ammonium polyphosphate alone, which has a bad effect on the mechanical properties of PP plastics.

[0021] The sisal fiber of the invention is treated with sodium hydroxide alkali and oxidized with potassium permanganate, so that the interface performance of the sisal fiber is improved, the interface interaction between the sisal fiber and the polypropylene is improved, and the impact strength and bending strength of the PP plastic are improved.

[0022] The ammonium polyphosphate coated in the microcapsules of the present invention and the flame-retardant silicon element in the polyacrylate microcapsules form an NP-Si synergistic flame-retardant system, which promotes the formation of a carbon-silicon-inorganic barrier layer when the substrate burns, reduces heat transfer and hinders the contact between the substrate and oxygen, thus achieving a good flame-retardant effect. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0024] The sisal fiber was added into 12% sodium hydroxide, stirred at 30°C for 5 hours, the sisal fiber was taken out, washed with water and dried, and then added into 0.8% potassium permanganate aqueous solution, stirred at 25°C for 1 hour, filtered, washed with water and dried to obtain potassium permanganate oxidized sisal fiber.

[0025] Example 1

[0026] 17.8 g of 3-chloro-2-hydroxypropyl methacrylate and 13.8 g of pyridine were added to 250 mL of toluene, and 12.9 g of trimethylsilyl chloride was added dropwise in a nitrogen atmosphere. The mixture was reacted at 30° C. for 12 h, and concentrated under reduced pressure. The siloxane acrylate intermediate was obtained after washing with petroleum ether.

[0027] Add 25g of siloxane acrylate intermediate to 400mL of tetrahydrofuran, add 6.8g of sodium hydride and 0.65g of tetrabutylammonium bromide under ice-water bath, react at 35°C for 8h, add water after reaction, concentrate under reduced pressure to remove tetrahydrofuran, add ethyl acetate, shake and extract, concentrate the ethyl acetate organic phase to obtain epoxy siloxane acrylate monomer. The reaction route is as follows:

[0028]

[0029] Add 30 g of epoxysiloxane acrylate monomer to 300 mL of N,N-dimethylformamide, add 3.9 g of azobisisobutyronitrile dropwise in a nitrogen atmosphere, react at 60°C for 6 h, cool, pour the solution into ethanol to precipitate, filter, wash with ethanol, and dry to obtain epoxysiloxane polyacrylate.

[0030] Add 15 g of epoxysiloxane polyacrylate to 500 mL of N,N-dimethylformamide, stir and disperse, add 100 g of ammonium polyphosphate and 8 g of cross-linking agent ethylenediamine, reflux at 55°C for 12 h, filter, wash with water, and dry to obtain polyacrylate-coated ammonium polyphosphate microcapsules.

[0031] 500g of polypropylene, 75g of potassium permanganate-oxidized sisal fiber, and 50g of polyacrylate-coated ammonium polyphosphate microcapsules were added into an open mill, mixed at 200°C for 5min, and then heat- and pressure-treated at 195°C for 10min at a pressure of 10MPa in a flat vulcanizer to obtain green and environmentally friendly PP plastic.

[0032] Example 2

[0033] 17.8 g of 3-chloro-2-hydroxypropyl methacrylate and 15.6 g of pyridine were added to 300 mL of toluene, and 14.3 g of trimethylsilyl chloride was added dropwise in a nitrogen atmosphere. The mixture was reacted at 45 °C for 6 h, and concentrated under reduced pressure. The siloxane acrylate intermediate was obtained after washing with petroleum ether.

[0034] Add 25 g of siloxane acrylate intermediate to 300 mL of tetrahydrofuran, add 5.5 g of sodium hydride and 0.5 g of tetrabutylammonium bromide under an ice-water bath, react at 25 ° C for 12 hours, add water after the reaction, concentrate under reduced pressure to remove tetrahydrofuran, add ethyl acetate, shake and extract, concentrate the ethyl acetate organic phase to obtain epoxy siloxane acrylate monomer.

[0035] Add 30 g of epoxysiloxane acrylate monomer to 250 mL of N,N-dimethylformamide, add 3.2 g of azobisisobutyronitrile dropwise in a nitrogen atmosphere, react at 55° C. for 6 h, cool, pour the solution into ethanol to precipitate, filter, wash with ethanol, and dry to obtain epoxysiloxane polyacrylate.

[0036] Add 25 g of epoxysiloxane polyacrylate to 500 mL of N,N-dimethylformamide, stir and disperse, add 100 g of ammonium polyphosphate and 12 g of cross-linking agent ethylenediamine, reflux at 65°C for 6 h, filter, wash with water, and dry to obtain polyacrylate-coated ammonium polyphosphate microcapsules.

[0037] 500g of polypropylene, 180g of potassium permanganate-oxidized sisal fiber, and 100g of polyacrylate-coated ammonium polyphosphate microcapsules were added to an open mill, mixed at 190°C for 10 min, and then kept warm and pressure-treated at 190°C for 10 min in a flat vulcanizer at a pressure of 15MPa to obtain green and environmentally friendly PP plastic.

[0038] Example 3

[0039] Add 17.8 g of 3-chloro-2-hydroxypropyl methacrylate and 12.4 g of pyridine to 20 ml of toluene, add 11.5 g of trimethylsilyl chloride dropwise in a nitrogen atmosphere, react at 30° C. for 10 h, concentrate under reduced pressure, and wash with petroleum ether to obtain the siloxane acrylate intermediate.

[0040] Add 25 g of siloxane acrylate intermediate to 400 mL of tetrahydrofuran, add 7.5 g of sodium hydride and 0.75 g of tetrabutylammonium bromide under an ice-water bath, react at 25 ° C for 12 hours, add water after the reaction, concentrate under reduced pressure to remove tetrahydrofuran, add ethyl acetate, shake and extract, concentrate the ethyl acetate organic phase to obtain epoxy siloxane acrylate monomer.

[0041] Add 30 g of epoxysiloxane acrylate monomer to 200 mL of N,N-dimethylformamide, add 2.4 g of azobisisobutyronitrile dropwise in a nitrogen atmosphere, react at 70°C for 3 h, cool, pour the solution into ethanol to precipitate, filter, wash with ethanol, and dry to obtain epoxysiloxane polyacrylate.

[0042] Add 35 g of epoxysiloxane polyacrylate to 500 mL of N,N-dimethylformamide, stir and disperse, add 100 g of ammonium polyphosphate and 15 g of cross-linking agent ethylenediamine, reflux at 65°C for 6 h, filter, wash with water, and dry to obtain polyacrylate-coated ammonium polyphosphate microcapsules.

[0043] 500g of polypropylene, 300g of potassium permanganate-oxidized sisal fiber, and 175g of polyacrylate-coated ammonium polyphosphate microcapsules were added to an open mill, mixed at 180°C for 10min, and then heat- and pressure-treated at 200°C for 5min at a pressure of 10MPa in a flat vulcanizer to obtain green and environmentally friendly PP plastic.

[0044] Weigh 50g of polyacrylate-coated ammonium polyphosphate microcapsules and ammonium polyphosphate respectively and add them to 1L of water, stir at 25℃, 50℃, and 75℃ for 1h, collect the upper liquid by centrifugation, dry and weigh to obtain the mass m of ammonium polyphosphate dissolved in water, and calculate the solubility W, W = (m / V) g / L, V is the volume of water. The greater the solubility, the worse the moisture and heat resistance.

[0045]

[0046]

[0047] The solubility of the coated ammonium polyphosphate in water at temperatures of 25°C, 50°C, and 75°C reaches 4.96 g / L, 15.02 g / L, and 35.19 g / L, and its moisture and heat resistance is poor.

[0048] In Example 3, when the mass of epoxysiloxane polyacrylate is 35% of ammonium polyphosphate, the solubility of ammonium polyphosphate in water at 25°C, 50°C, and 75°C is only 2.04g / L, 5.96g / L, and 11.10g / L, and it has excellent moisture and heat resistance.

[0049] Comparative Example 1

[0050] 500g of polypropylene, 75g of potassium permanganate-oxidized sisal fiber and 50g of ammonium polyphosphate were added into an open mill and mixed at 200°C for 5min. Then, the mixture was subjected to heat and pressure maintenance treatment at 195°C for 10min at a pressure of 10MPa in a flat vulcanizer to obtain green and environmentally friendly PP plastic.

[0051] Comparative Example 2

[0052] 500g of polypropylene, 75g of potassium permanganate-oxidized sisal fiber, and 50g of epoxysiloxane polyacrylate were added to an open mill, mixed at 200°C for 5 minutes, and then subjected to heat and pressure treatment at 195°C for 10 minutes at a pressure of 10MPa in a flat vulcanizer to obtain green and environmentally friendly PP plastic.

[0053] Comparative Example 3

[0054] 500g of polypropylene, 75g of potassium permanganate-oxidized sisal fiber, 10g of epoxysiloxane polyacrylate and 40g of ammonium polyphosphate were added to an open mill and mixed at 200°C for 5min. Then, the mixture was subjected to heat and pressure maintenance treatment at 195°C for 10min at a pressure of 10MPa in a flat vulcanizer to obtain green and environmentally friendly PP plastic.

[0055] Comparative Example 4

[0056] 500g of polypropylene, 75g of sisal fiber, and 50g of polyacrylate-coated ammonium polyphosphate microcapsules were added to an open mill, mixed at 200°C for 5min, and then heat- and pressure-treated at 195°C for 10min at a pressure of 10MPa in a flat vulcanizer to obtain green and environmentally friendly PP plastic.

[0057] The performance test of green and environmentally friendly PP plastic is shown in the following table.

[0058]

[0059] Each embodiment adds polyacrylate-coated ammonium polyphosphate microcapsules. Since polyacrylate polymers have good compatibility with polypropylene, the microcapsules coated with ammonium polyphosphate have excellent dispersion in polypropylene PP plastics, avoiding the addition of microcapsules and the addition of ammonium polyphosphate alone, which will have a bad impact on the mechanical properties of PP plastics. At the same time, the sisal fiber oxidized by potassium permanganate improves the interface properties of the sisal fiber, improves the interface interaction between the sisal fiber and polypropylene, and improves the impact strength and bending strength of the PP plastic. The impact strength reaches 33.5-40.1 kJ / m 2 , the bending strength reaches 36.1-45.4MPa. The limiting oxygen index reaches 28.5-34.2%.

[0060] The flame-retardant silicon element in the microcapsule-encapsulated ammonium polyphosphate and the polyacrylate microcapsule added in each embodiment forms an NP-Si synergistic flame-retardant system, which promotes the formation of a carbon-silicon-inorganic barrier layer when the substrate burns, reduces heat transfer and hinders the contact between the substrate and oxygen, thus achieving a good flame-retardant effect.

[0061] Compared with Example 1, Comparative Example 1 only adds ammonium polyphosphate, which has poor dispersibility in polypropylene and oxidized sisal fiber, has a greater impact on the strength of PP plastic, and does not add polyacrylate microcapsules containing flame-retardant silicon elements, resulting in poor flame retardancy.

[0062] Comparative Example 2, in which only epoxysiloxane polyacrylate was added without ammonium polyphosphate, had the worst flame retardancy.

[0063] In Comparative Example 3, epoxysiloxane polyacrylate and ammonium polyphosphate were added, but the two did not form a microcapsule structure. The dispersibility of ammonium polyphosphate in polypropylene and oxidized sisal fiber was poor, which had a great impact on the flame retardant properties and strength of PP plastics. The limiting oxygen index was lower than that of Example 1.

[0064] The sisal fiber added in Comparative Example 4 was not oxidized by potassium permanganate, and the interface interaction between the fiber and the polypropylene was poor, so the mechanical strength of the PP plastic was the lowest.

Claims

1. A method for preparing green and environmentally friendly PP plastic, characterized in that: The green and environmentally friendly PP plastic includes the following raw materials: 100 parts by weight of polypropylene, 15-60 parts by weight of potassium permanganate oxidized sisal fiber, and 10-35 parts by weight of polyacrylate-coated ammonium polyphosphate microcapsules; the preparation method is as follows: Step S1, adding epoxysiloxane polyacrylate to N,N-dimethylformamide, stirring and dispersing, adding ammonium polyphosphate and cross-linking agent ethylenediamine, filtering after reaction, washing with water, and drying to obtain polyacrylate-coated ammonium polyphosphate microcapsules; Step S2, adding polypropylene, potassium permanganate oxidized sisal fiber, and polyacrylate-coated ammonium polyphosphate microcapsules into an open mill, mixing at 180-200° C. for 5-10 min, and then heat-maintaining and pressure-maintaining treatment at 190-200° C. for 5-10 min at a pressure of 10-15 MPa in a flat vulcanizer to obtain green and environmentally friendly PP plastic; The preparation method of the epoxysiloxane polyacrylate is as follows: Step (1), adding 100 parts by weight of 3-chloro-2-hydroxypropyl methacrylate and 70-88 parts by weight of pyridine to toluene, adding 65-80 parts by weight of trimethylchlorosilane dropwise in a nitrogen atmosphere, reacting at 30-45° C. for 6-12 hours, concentrating under reduced pressure, and washing with petroleum ether to obtain a siloxane acrylate intermediate; Step (2), adding a siloxane acrylate intermediate to tetrahydrofuran, adding sodium hydride and tetrabutylammonium bromide under an ice-water bath, adding water after the reaction, concentrating under reduced pressure to remove tetrahydrofuran, adding ethyl acetate, extracting by shaking, concentrating the ethyl acetate organic phase, and obtaining an epoxysiloxane acrylate monomer; 2,3-epoxy-1-propanol is also added in step (2); Step (3), adding epoxysiloxane acrylate monomer to N,N-dimethylformamide, adding azobisisobutyronitrile dropwise in a nitrogen atmosphere, cooling after the reaction, pouring the solution into ethanol to precipitate, filtering, washing with ethanol, and drying to obtain epoxysiloxane polyacrylate.

2. The method for preparing green and environmentally friendly PP plastic according to claim 1, characterized in that: In the step S1, the mass of the epoxysiloxane polyacrylate and ethylenediamine are 15-35% and 8-15% of the ammonium polyphosphate, respectively.

3. The method for preparing green and environmentally friendly PP plastic according to claim 1, characterized in that: In step S1, the reaction is refluxed at a temperature of 55-65° C. for 6-12 hours.

4. The method for preparing green and environmentally friendly PP plastic according to claim 1, characterized in that: In the step (2), the mass of sodium hydride and tetrabutylammonium bromide are 22-30% and 2-3% of the siloxane acrylate intermediate respectively.

5. The method for preparing green and environmentally friendly PP plastic according to claim 1, characterized in that: The reaction in step (2) is carried out at a temperature of 25-35° C. for 8-18 hours.

6. The method for preparing green and environmentally friendly PP plastic according to claim 1, characterized in that: The mass of azobisisobutyronitrile in step (3) is 0.8-1.3% of the epoxysiloxane acrylate monomer.

7. The method for preparing green and environmentally friendly PP plastic according to claim 4, characterized in that: The reaction in step (3) is carried out at a temperature of 55-70° C. for 3-6 hours.

Images