A micro-expansion plastic filler and a method for preparing the same

Abstract

The present application relates to a kind of micro-expansion plastic fillers and its preparation method, belong to polymer material technical field.The present application is by the reaction of heteroazosilatrane and isocyanuric acid triglycidyl ester, then with isocyanate base propyl triethoxysilane reaction, obtain polyfunctional silane coupling agent, then linear quartz fiber and globular nano zirconium silicate are modified using silane coupling agent, and using modified quartz fiber and modified nano zirconium silicate with hydroxyl modified polypropylene and polypropylene are melt extrusion granulation, finally carry out steam foaming.Heteroazosilatrane and isocyanuric acid structure can provide support for cell formation, its rigid cyclic structure can provide steric hindrance for quartz fiber and zirconium silicate, avoid agglomeration, functional silane coupling agent is added during steam foaming process, can form crosslinked network structure by hydrolysis, improve cell stability and micro-expansion plastic filler's heat insulation sound insulation mechanical property.

Description

Technical Field

[0001] This invention relates to a micro-expansion plastic filler and its preparation method, belonging to the field of polymer materials technology. Background Technology

[0002] Foamed plastics possess advantages such as lightweight, heat insulation, cushioning, electrical insulation, corrosion resistance, and low price. Therefore, they are widely used in daily necessities, packaging, industry, agriculture, transportation, military industry, and aerospace industry. The main varieties include polyurethane foam, polystyrene foam, polyethylene foam, and polypropylene foam. However, polyurethane foam releases harmful isocyanate residues during the foaming process, and the foamed material cannot be recycled. Polystyrene foam typically uses chlorofluorocarbons (CFCs) or butane during its foaming process, which has adverse environmental impacts, is difficult to degrade, and easily causes white pollution. Polyethylene foam also exhibits performance deviations. Polypropylene foam possesses good rigidity, heat resistance, low-temperature resistance, dimensional stability, and energy absorption properties. Therefore, due to its excellent heat resistance, hygiene, insulation, and good environmental effects, polypropylene foam products have a wide range of applications and play an important role in packaging, automotive, and construction industries.

[0003] Currently, expanded foamed polypropylene beads are typically prepared by foaming polypropylene resin, and then expanded foamed polypropylene products are made from these beads. To improve the mechanical properties of expanded foamed polypropylene, an appropriate amount of inorganic rigid filler is usually added. However, inorganic rigid fillers have poor compatibility with the polypropylene matrix. While improving the mechanical properties of the material, they also affect the viscoelasticity of the polypropylene melt and the foaming process, leading to deterioration of the cell structure and consequently affecting the material's thermal and sound insulation performance. Summary of the Invention

[0004] The purpose of this invention is to provide a micro-expansion plastic filler and its preparation method, which can solve the problem that the use of inorganic fillers to modify polypropylene foam materials leads to a decrease in the viscoelasticity of the polypropylene melt and a decrease in the thermal and sound insulation performance of the material.

[0005] This invention provides a method for preparing micro-expansion plastic fillers, comprising the following steps:

[0006] (1) Triisopropanolamine and γ-aminopropyltriethoxysilane were mixed and reacted in a molar ratio of 1:1 to obtain γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silazane[3,3,3,01,5]undecane, the structural formula of which is as follows:

[0007]

[0008] (2) γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silane[3,3,3,01,5]undecane and triglycidyl isocyanurate were mixed and reacted to obtain a hydroxyl-isocyanate compound; the molar ratio of the hydroxyl-isocyanate compound to the tricyclic amino compound was 3:1; the structural formula of the hydroxyl-isocyanate compound is as follows:

[0009]

[0010] (3) Mix and react the tricyclic isocyanuric acid hydroxy compound and γ-isocyanate propyltriethoxysilane to obtain a functional silane coupling agent; the molar ratio of the tricyclic isocyanuric acid hydroxy compound and γ-isocyanate propyltriethoxysilane is 1:3.

[0011] (4) After mixing the functional silane coupling agent, water and acetic acid, let it stand, and then mix it with quartz fiber to react and obtain modified quartz fiber.

[0012] (5) After mixing the functional silane coupling agent, water and acetic acid, let it stand, and then mix it with nano zirconium silicate to react and obtain modified nano zirconium silicate.

[0013] (6) Modified quartz fiber, modified nano zirconium silicate, functional silane coupling agent, hydroxyl-modified polypropylene and polypropylene are melt-blended, extruded and granulated to obtain a mixture; hydroxyl-modified polypropylene is prepared by reacting chlorinated polypropylene, hydroxyl-containing aryl compound, hydroxyl protectant and catalyst.

[0014] (7) The mixture is steam-foamed to obtain micro-expansion plastic filler.

[0015] Preferably, in step (1), the mixing reaction is carried out under reflux conditions for 3 to 5 hours.

[0016] Preferably, a catalyst is added during the mixing reaction in step (2), the catalyst is triethylamine, and the mass of the catalyst is 1 to 1.5% of the mass of triglycidyl isocyanurate; the temperature of the mixing reaction in step (2) is 35 to 45°C, and the time is 3 to 5 hours.

[0017] Preferably, the catalyst used in the mixing reaction in step (3) is triethylamine, and the mass of triethylamine is 1 to 1.5% of the mass of the tri-azosilane tricyclic isocyanuric acid hydroxy compound; the temperature of the mixing reaction is 70 to 90°C, and the time is 18 to 24 hours.

[0018] Preferably, in step (4), the mass ratio of quartz fiber, functional silane coupling agent, water and acetic acid is 1.5:1 to 1.2:100:2 to 2.5; the standing time is 45 to 65 minutes; and the mixing reaction time is 4 to 5 hours.

[0019] Preferably, in step (5), the mass ratio of nano-zirconium silicate, functional silane coupling agent, water and acetic acid is 1.5:1.5~2:100:2~2.5; the standing time is 45~65min; and the mixing reaction time is 4~5h.

[0020] Preferably, in step (6), the aryl compound containing hydroxyl groups is phenylethanol, and the hydroxyl protecting agent is phosphoric acid; the preparation method of hydroxyl-modified polypropylene is as follows: after dissolving chlorinated polypropylene, a chlorinated polypropylene solution is obtained; the chlorinated polypropylene solution, phenylethanol, phosphoric acid and boron trifluoride are mixed and reacted to obtain hydroxyl-modified polypropylene; the mass ratio of chlorinated polypropylene, phenylethanol, phosphoric acid and boron trifluoride is 5:6.2:5:1.5.

[0021] Preferably, in step (6), the temperature of melt blending and extrusion is 180-190°C; the mass ratio of hydroxyl-modified polypropylene to polypropylene is 30-40:60-70; the mass of modified quartz fiber is 1.2-1.5% of the total mass of hydroxyl-modified polypropylene and polypropylene; and the mass of modified nano-zirconium silicate is 0.8-1.2% of the total mass of hydroxyl-modified polypropylene and polypropylene.

[0022] Preferably, in step (7), when the steam is foamed, the steam pressure is 0.35 to 0.5 MPa and the ventilation time is 40 to 50 seconds.

[0023] This invention provides a micro-expansion plastic filler, which is prepared by the method described above.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) This invention involves reacting a tricyclic amino compound of heteroazosilane with triglycidyl isocyanate, followed by a reaction with isocyanate-propyltriethoxysilane to obtain a multi-component silane coupling agent containing a tricyclic structure of heteroazosilane and an isocyanate structure. The obtained functional silane coupling agent is then used to modify linear quartz fibers and spherical nano-zirconium silicate. The modified quartz fibers and modified nano-zirconium silicate are then melt-extruded and granulated with hydroxyl-modified polypropylene and polypropylene. Finally, steam foaming is performed to obtain a micro-expanding plastic filler. The tricyclic structure of heteroazosilane and the isocyanate structure in the micro-expanding plastic filler provide support for cell formation, and its rigid ring structure provides steric hindrance to the quartz fibers and nano-zirconium silicate, preventing agglomeration. Simultaneously, the addition of the functional silane coupling agent during steam foaming allows for further hydrolysis, forming a cross-linked network structure with hydroxyl polypropylene and the nano-filler, thus improving cell stability and the thermal insulation, sound insulation, and mechanical properties of the micro-expanding plastic filler.

[0026] (2) In the molding and foaming process of micro-expansion plastic filler, one-dimensional linear modified quartz fiber and three-dimensional spherical modified nano-zirconium silicate can achieve barrier filling effect. The linear modified quartz fiber can separate and block the spherical modified nano-zirconium silicate, while the spherical modified nano-zirconium silicate can prevent the linear modified quartz fiber from approaching and accumulating. This makes the one-dimensional linear modified quartz fiber and the three-dimensional spherical modified nano-zirconium silicate evenly dispersed in the micro-expansion plastic filler. The two play a synergistic role. The surface-grafted functional silane coupling agent can further improve the steric hindrance between quartz fiber and nano-zirconium silicate, improve the compatibility with polypropylene, improve the foaming performance and cell stability and uniformity, and thus improve the comprehensive performance of micro-expansion plastic filler.

[0027] (3) This invention modifies nano-zirconium silicate and quartz fiber using a multi-functional coupling agent, which allows the tricyclic nitrogen silicon structure and isocyanuric acid structure to be uniformly and firmly coated on the surface of the nanomaterials. This improves the compatibility between the nanomaterials and polypropylene, as well as the barrier properties between the nanomaterials, thereby enhancing the viscoelasticity of the polypropylene melt and facilitating foaming and cell stability. Experimental results show that the mixture prepared in this invention has a small loss factor, indicating a fast elastic response of the melt. Furthermore, experimental results show that modifying nano-zirconium silicate and quartz fiber with a functional silane coupling agent and using both simultaneously can significantly improve the elastic response of the material melt, reduce viscous dissipation, stabilize the cell structure during foaming, and improve the overall performance of the final expanded material.

[0028] (4) In this invention, polypropylene and modified filler are modified by coupling agent to form micro-crosslinked filler. The filler and polypropylene are mixed and then molded to obtain a composite material with a small thermal conductivity, large compressive strength, tensile strength, notched impact strength and flexural strength, and good flame retardant and heat resistance properties, which has good application prospects. Detailed Implementation

[0029] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the present invention.

[0030] Example 1

[0031] The preparation method of the micro-expansion plastic filler in this embodiment includes the following steps:

[0032] (1) 25 mmol of triisopropanolamine and 25 mmol of γ-aminopropyltriethoxysilane were added to a reaction flask and heated under reflux for 3 h with stirring. The ethanol generated in the reaction was removed by vacuum distillation to obtain a tricyclic amino azide, namely γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silane[3,3,3,01,5]undecane, with the following structural formula:

[0033]

[0034] (2) The tricyclic amino compound of heteroazosilane was dissolved in dioxane to obtain a 10% solution A; triglycidyl isocyanurate was dissolved in dioxane to obtain a 15% solution B; solutions A and B were stirred evenly, then triethylamine catalyst was added, the mixture was heated to 35°C, and stirred for 3 hours. The reaction mixture was then distilled under reduced pressure to remove the solvent and triethylamine, yielding the tricyclic amino compound of heteroazosilane-isocyanurate hydroxyl compound; wherein the molar ratio of the tricyclic amino compound of heteroazosilane to triglycidyl isocyanurate was 3:1, and the mass of the triethylamine catalyst was 1% of the mass of triglycidyl isocyanurate; the structural formula of the tricyclic amino compound of heteroazosilane-isocyanurate hydroxyl compound is as follows:

[0035]

[0036] (3) Dissolve the tricyclic isocyanuric acid hydroxy compound in dichloromethane to obtain a 10% solution C. Then add γ-isocyanate propyltriethoxysilane and the catalyst triethylamine to solution C, heat to 70°C, stir and reflux for 18 h, remove the solvent and triethylamine by vacuum distillation to obtain the functional silane coupling agent. The molar ratio of the tricyclic isocyanuric acid hydroxy compound and γ-isocyanate propyltriethoxysilane is 1:3, and the mass of triethylamine is 1% of the mass of the tricyclic isocyanuric acid hydroxy compound.

[0037] (4) Add the functional silane coupling agent, water and acetic acid to the reaction vessel, stir evenly and let stand for 45 min, then add quartz fiber (the diameter of the quartz fiber is 3 to 5 μm) to the reaction vessel, stir and react for 4 h, filter, wash and dry to obtain modified quartz fiber; wherein, the mass ratio of quartz fiber, functional silane coupling agent, water and acetic acid is 1.5:1:100:2.

[0038] (5) Add the functional silane coupling agent, water and acetic acid to the reaction vessel, stir evenly and let stand for 45 min, then add nano zirconium silicate to the reaction vessel, stir and react for 4 h, filter, wash and dry to obtain modified nano zirconium silicate; wherein, the mass ratio of nano zirconium silicate, functional silane coupling agent, water and acetic acid is 1.5:1.5:100:2.

[0039] (6) Add 5g of chlorinated polypropylene (chlorine content of 37%, molecular weight of 180,000 to 200,000) to 30mL of decahydronaphthalene, heat to 120℃ with stirring until the chlorinated polypropylene dissolves, then cool to 100℃, add 6.2g of phenylethanol and 5g of phosphoric acid to the chlorinated polypropylene solution, stir for 30min, then add 1.5g of boron trifluoride catalyst, continue stirring at 100℃ for 2h, cool the reaction system to room temperature and pour it into 200mL of 1% HCl ethanol solution, let stand for 1h, filter, wash the filter cake with dilute hydrochloric acid, then wash with sodium bicarbonate solution, and finally wash with water until the filtrate is neutral. After vacuum drying, hydroxyl-modified polypropylene with a hydroxyl content of 6.5% is obtained.

[0040] (7) Modified quartz fiber, modified nano-zirconium silicate, functional silane coupling agent (the molar amount of functional silane coupling agent is 30% of the molar amount of hydroxyl in hydroxyl-modified polypropylene), hydroxyl-modified polypropylene and polypropylene (molecular weight of 120,000 to 150,000) are added to an extruder for melt blending, extrusion and granulation to obtain a mixture; wherein, the temperature of melt blending and extrusion is 180℃; the mass ratio of hydroxyl-modified polypropylene to polypropylene is 30:70, the mass of modified quartz fiber is 1.2% of the total mass of hydroxyl-modified polypropylene and polypropylene, and the mass of modified nano-zirconium silicate is 1.2% of the total mass of hydroxyl-modified polypropylene and polypropylene.

[0041] (8) Place the mixture in a high-pressure reactor, then fill the constant temperature high-pressure reactor with steam at a pressure of 0.35 MPa and a ventilation time of 40 s. Then release the steam in the high-pressure reactor quickly, and then place the mixture in the high-pressure reactor in the air so that the air enters the bubbles. Then let it stand for 10 h. After the bubbles are shaped, the micro-expansion plastic filler is obtained.

[0042] Example 2

[0043] The preparation method of the micro-expansion plastic filler in this embodiment includes the following steps:

[0044] (1) 25 mmol of triisopropanolamine and 25 mmol of γ-aminopropyltriethoxysilane were added to a reaction flask and heated under reflux for 4 h with stirring. The ethanol generated in the reaction was removed by vacuum distillation to obtain a tricyclic amino azide, namely γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silane[3,3,3,01,5]undecane, with the following structural formula:

[0045]

[0046] (2) The tricyclic amino compound of heteroazosilane was dissolved in dioxane to obtain a 12% solution A; triglycidyl isocyanate was dissolved in dioxane to obtain a 12% solution B; solutions A and B were stirred evenly, then triethylamine catalyst was added, the mixture was heated to 40°C, and stirred for 4 hours. The reaction mixture was then distilled under reduced pressure to remove the solvent and triethylamine, yielding the tricyclic amino compound of heteroazosilane-isocyanuric acid hydroxyl compound; wherein the molar ratio of the tricyclic amino compound of heteroazosilane to triglycidyl isocyanate was 3:1, and the mass of the triethylamine catalyst was 1.2% of the mass of triglycidyl isocyanate; the structural formula of the tricyclic amino compound of heteroazosilane-isocyanuric acid hydroxyl compound is as follows:

[0047]

[0048] (3) Dissolve the tricyclic isocyanuric acid hydroxy compound in dichloromethane to obtain a solution C with a mass fraction of 12%. Then, add γ-isocyanate-propyltriethoxysilane and the catalyst triethylamine to solution C, heat to 80°C, stir and reflux for 20 h, and remove the solvent and triethylamine by vacuum distillation to obtain the functional silane coupling agent. The molar ratio of the tricyclic isocyanuric acid hydroxy compound and γ-isocyanate-propyltriethoxysilane is 1:3, and the mass of triethylamine is 1.2% of the mass of the tricyclic isocyanuric acid hydroxy compound.

[0049] (4) Add the functional silane coupling agent, water and acetic acid to the reaction vessel, stir evenly and let stand for 50 min, then add quartz fiber (the diameter of the quartz fiber is 3 to 5 μm) to the reaction vessel, stir and react for 4.5 h, filter, wash and dry to obtain modified quartz fiber; wherein, the mass ratio of quartz fiber, functional silane coupling agent, water and acetic acid is 1.5:1.1:100:2.2.

[0050] (5) Add the functional silane coupling agent, water and acetic acid to the reaction vessel, stir evenly and let stand for 50 min, then add nano zirconium silicate to the reaction vessel, stir and react for 4.5 h, filter, wash and dry to obtain modified nano zirconium silicate; wherein, the mass ratio of nano zirconium silicate, functional silane coupling agent, water and acetic acid is 1.5:1.8:100:2.3.

[0051] (6) Add 5g of chlorinated polypropylene (chlorine content of 37%, molecular weight of 180,000 to 200,000) to 30mL of decahydronaphthalene, heat to 120℃ with stirring until the chlorinated polypropylene dissolves, then cool to 100℃, add 6.2g of phenylethanol and 5g of phosphoric acid to the chlorinated polypropylene solution, stir for 30min, then add 1.5g of boron trifluoride catalyst, continue stirring at 100℃ for 2h, cool the reaction system to room temperature and pour it into 200mL of 1% HCl ethanol solution, let stand for 1h, filter, wash the filter cake with dilute hydrochloric acid, then wash with sodium bicarbonate solution, and finally wash with water until the filtrate is neutral. After vacuum drying, hydroxyl-modified polypropylene with a hydroxyl content of 6.5% is obtained.

[0052] (7) Modified quartz fiber, modified nano-zirconium silicate, functional silane coupling agent (the molar amount of functional silane coupling agent is 32% of the molar amount of hydroxyl in hydroxyl-modified polypropylene), hydroxyl-modified polypropylene and polypropylene (molecular weight of 120,000 to 150,000) are added to an extruder for melt blending, extrusion and granulation to obtain a mixture; wherein, the temperature of melt blending and extrusion is 185℃; the mass ratio of hydroxyl-modified polypropylene to polypropylene is 35:65, the mass of modified quartz fiber is 1.3% of the total mass of hydroxyl-modified polypropylene and polypropylene, and the mass of modified nano-zirconium silicate is 1% of the total mass of hydroxyl-modified polypropylene and polypropylene.

[0053] (8) Place the mixture in a high-pressure reactor, then fill the constant temperature high-pressure reactor with steam at a pressure of 0.4 MPa and a ventilation time of 45 s. Then release the steam in the high-pressure reactor quickly, and then place the mixture in the high-pressure reactor in the air so that the air enters the bubbles. Then let it stand for 11 hours. After the bubbles are shaped, the micro-expansion plastic filler is obtained.

[0054] Example 3

[0055] The preparation method of the micro-expansion plastic filler in this embodiment includes the following steps:

[0056] (1) 25 mmol of triisopropanolamine and 25 mmol of γ-aminopropyltriethoxysilane were added to a reaction flask and heated under reflux for 5 h with stirring. The ethanol generated in the reaction was removed by vacuum distillation to obtain a tricyclic amino azide, namely γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silane[3,3,3,01,5]undecane, with the following structural formula:

[0057]

[0058] (2) The tricyclic amino compound of heteroazosilane was dissolved in dioxane to obtain a 15% solution A; triglycidyl isocyanurate was dissolved in dioxane to obtain a 10% solution B; solutions A and B were stirred evenly, then triethylamine catalyst was added, the mixture was heated to 45°C, and stirred for 5 hours. The reaction mixture was then distilled under reduced pressure to remove the solvent and triethylamine, yielding the tricyclic amino compound of heteroazosilane-isocyanurate hydroxyl compound; wherein the molar ratio of the tricyclic amino compound of heteroazosilane to triglycidyl isocyanurate was 3:1, and the mass of the triethylamine catalyst was 1.5% of the mass of triglycidyl isocyanurate; the structural formula of the tricyclic amino compound of heteroazosilane-isocyanurate hydroxyl compound is as follows:

[0059]

[0060] (3) Dissolve the tricyclic isocyanuric acid hydroxy compound in dichloromethane to obtain a solution C with a mass fraction of 15%. Then add γ-isocyanate-propyltriethoxysilane and the catalyst triethylamine to solution C, heat to 90°C, stir and reflux for 24 h, remove the solvent and triethylamine by vacuum distillation to obtain the functional silane coupling agent. The molar ratio of the tricyclic isocyanuric acid hydroxy compound and γ-isocyanate-propyltriethoxysilane is 1:3, and the mass of triethylamine is 1.5% of the mass of the tricyclic isocyanuric acid hydroxy compound.

[0061] (4) Add the functional silane coupling agent, water and acetic acid to the reaction vessel, stir evenly and let stand for 65 min, then add quartz fiber (the diameter of the quartz fiber is 3 to 5 μm) to the reaction vessel, stir and react for 5 h, filter, wash and dry to obtain modified quartz fiber; wherein, the mass ratio of quartz fiber, functional silane coupling agent, water and acetic acid is 1.5:1.2:100:2.5.

[0062] (5) Add the functional silane coupling agent, water and acetic acid to the reaction vessel, stir evenly and let stand for 65 min, then add nano zirconium silicate to the reaction vessel, stir and react for 5 h, filter, wash and dry to obtain modified nano zirconium silicate; wherein, the mass ratio of nano zirconium silicate, functional silane coupling agent, water and acetic acid is 1.5:2:100:2.5.

[0063] (6) Add 5g of chlorinated polypropylene (chlorine content of 37%, molecular weight of 180,000 to 200,000) to 30mL of decahydronaphthalene, heat to 120℃ with stirring until the chlorinated polypropylene dissolves, then cool to 100℃, add 6.2g of phenylethanol and 5g of phosphoric acid to the chlorinated polypropylene solution, stir for 30min, then add 1.5g of boron trifluoride catalyst, continue stirring at 100℃ for 2h, cool the reaction system to room temperature and pour it into 200mL of 1% HCl ethanol solution, let stand for 1h, filter, wash the filter cake with dilute hydrochloric acid, then wash with sodium bicarbonate solution, and finally wash with water until the filtrate is neutral. After vacuum drying, hydroxyl-modified polypropylene with a hydroxyl content of 6.5% is obtained.

[0064] (7) Modified quartz fiber, modified nano-zirconium silicate, functional silane coupling agent (the molar amount of functional silane coupling agent is 35% of the molar amount of hydroxyl in hydroxyl-modified polypropylene), hydroxyl-modified polypropylene and polypropylene (molecular weight of 120,000 to 150,000) are added to an extruder for melt blending, extrusion and granulation to obtain a mixture; wherein, the temperature of melt blending and extrusion is 190℃; the mass ratio of hydroxyl-modified polypropylene and polypropylene is 40:60, the mass of modified quartz fiber is 1.5% of the total mass of hydroxyl-modified polypropylene and polypropylene, and the mass of modified nano-zirconium silicate is 0.8% of the total mass of hydroxyl-modified polypropylene and polypropylene.

[0065] (8) Place the mixture in a high-pressure reactor, then fill the constant temperature high-pressure reactor with steam at a pressure of 0.5 MPa and a ventilation time of 50 s. Then release the steam in the high-pressure reactor quickly, and then place the mixture in the high-pressure reactor in the air so that the air enters the bubbles. Then let it stand for 12 h. After the bubbles are shaped, the micro-expansion plastic filler is obtained.

[0066] Comparative Example 1

[0067] The difference between the preparation method of the micro-expansion plastic filler in this comparative example and the preparation method of the micro-expansion plastic filler in Example 1 is that supercritical carbon dioxide is used for foaming in step (8) of the preparation method of the micro-expansion plastic filler in this comparative example, and the foaming rate of the micro-expansion plastic filler obtained is the same as that of the micro-expansion plastic filler obtained in Example 1.

[0068] Comparative Example 2

[0069] The difference between the preparation method of the micro-expansion plastic filler in this comparative example and the preparation method of the micro-expansion plastic filler in Example 1 is that in step (2) of the preparation method of the micro-expansion plastic filler in this comparative example, the tricyclic amino compound of the diazo-silicon is replaced with phenylpropylamine.

[0070] Comparative Example 3

[0071] The difference between the preparation method of the micro-expansion plastic filler in this comparative example and the preparation method of the micro-expansion plastic filler in Example 1 is that the amount of modified quartz fiber in step (7) of the preparation method of the micro-expansion plastic filler in this comparative example is 0, and the mass of modified nano-zirconium silicate is 2.4% of the total mass of hydroxyl-modified polypropylene and polypropylene.

[0072] Comparative Example 4

[0073] The difference between the preparation method of the micro-expansion plastic filler in this comparative example and the preparation method of the micro-expansion plastic filler in Example 1 is that the amount of modified nano-zirconium silicate in step (7) of the preparation method of the micro-expansion plastic filler in this comparative example is 0, and the mass of modified quartz fiber is 2.4% of the total mass of hydroxyl-modified polypropylene and polypropylene.

[0074] Comparative Example 5

[0075] The difference between the preparation method of the micro-expansion plastic filler in this comparative example and the preparation method of the micro-expansion plastic filler in Example 1 is that the amount of functional silane coupling agent added in step (7) of the preparation method of the micro-expansion plastic filler in this comparative example is adjusted to 0.

[0076] Experimental Example 1

[0077] In order to examine the rheological properties of the mixtures in each embodiment and comparative example, and further examine their foaming effect, the loss factor of the mixtures prepared in step (7) of Examples 1-3 and Comparative Examples 2-5 at 178°C at different shear frequencies was tested, and the results are shown in Table 1.

[0078] Table 1 Loss Factors of Mixture at Different Shear Frequencies

[0079]

[0080] The loss factor is the phase difference between strain and stress experienced by the melt under alternating shear. It is significantly affected by stress and strain; the smaller the loss factor, the faster the elastic response of the melt. Table 1 shows that modifying nano-zirconium silicate and quartz fiber with functionalized silane coupling agents and using both simultaneously can significantly improve the elastic response of the material melt, reduce viscous dissipation, stabilize the cell structure during foaming, and improve the overall performance of the final expanded material.

[0081] Experiment Example 2

[0082] To evaluate the comprehensive performance of the micro-expansion plastic fillers in each embodiment and comparative example, the micro-expansion plastic fillers and polypropylene were mixed at a mass ratio of 1:1 and then molded to obtain test samples. The thermal conductivity, combustion performance, compressive strength, tensile strength, notched impact strength, and flexural strength of each sample were then tested. Thermal conductivity was measured using a thermal conductivity meter. Combustion performance was tested according to the method in standard GB / T8332-2008, and the results are expressed as self-extinguishing time. Compressive strength was tested according to the method in standard GBT8813-2008, tensile strength according to the method in standard GB / T 1040.2-2006, notched impact strength according to the method in standard GB / T 1843-2008, and flexural strength according to the method in standard GB / T 9341-2008. The test results of thermal conductivity, combustion performance, compressive strength, tensile strength, notched impact strength, and flexural strength of the materials in each embodiment and comparative example are shown in Table 2.

[0083] The table shows the thermal conductivity and flammability of the materials used in each embodiment and comparative example.

[0084] Burning performance, compressive strength, tensile strength, notched impact strength and flexural strength

[0085]

[0086] As shown in Table 2, based on Example 1 and Comparative Example 2, the tricyclic structure of the nitrogen-silicon can effectively improve the mechanical and thermal insulation properties of the micro-expansion plastic filler. Based on Example 1 and Comparative Examples 3-4, when the modified nano-zirconium silicate and modified quartz fiber in this invention are used simultaneously, the comprehensive performance of the micro-expansion plastic filler can be effectively improved. This may be because, during the foaming process of micro-expansion plastic filler, one-dimensional linear modified quartz fibers and three-dimensional spherical modified zirconium silicate nanoparticles can achieve barrier filling effects. The linear modified quartz fibers can separate and block the spherical modified zirconium silicate nanoparticles, while the spherical modified zirconium silicate nanoparticles can prevent the linear modified quartz fibers from gathering and accumulating. This results in the uniform dispersion of one-dimensional linear modified quartz fibers and three-dimensional spherical modified zirconium silicate nanoparticles in the micro-expansion plastic filler, with both playing a synergistic role. The surface-grafted functional silane coupling agent can further improve the steric hindrance between quartz fibers and zirconium silicate nanoparticles, improve the compatibility with polypropylene, improve the foaming performance and cell stability and uniformity, and thus improve the overall performance of the micro-expansion plastic filler.

[0087] Finally, the test samples obtained by molding using the micro-expansion plastic fillers of each embodiment and comparative example were subjected to sound insulation tests under different frequency sound waves (sample size and test conditions were the same). The test results are shown in Table 3. The unit of sound insulation is dB.

[0088] Table 3 shows the sound insulation properties of test samples obtained by molding using micro-expansion plastic fillers from various embodiments and comparative examples under different frequencies of sound waves.

[0089]

[0090] As shown in Table 3, the micro-expansion plastic filler of the present invention can effectively improve the sound insulation performance of polypropylene sheets, and has a higher sound insulation amount in the sound wave frequency range of 400-200Hz. While the micro-expansion plastic fillers of Comparative Examples 1-5 can also play a sound insulation role, their sound insulation amount in the sound wave frequency range of 400-200Hz is significantly lower than that of the present invention. The above results demonstrate that the present invention, by using a coupling agent with a tricyclic nitrogen silicon structure and an isocyanuric acid structure to modify polypropylene, along with fibers and zirconium silicate, can effectively improve the sound insulation performance of the material in the sound wave frequency range of 400-200Hz.

Claims

1. A method for preparing a micro-expansion plastic filler, characterized in that, Includes the following steps: (1) Triisopropanolamine and γ-aminopropyltriethoxysilane were mixed and reacted in a molar ratio of 1:1 to obtain γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silazane[3,3,3,01,5]undecane, the structural formula of which is as follows: (2) γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silane[3,3,3,01,5]undecane and triglycidyl isocyanurate were mixed and reacted to obtain a hydroxyl-isocyanate compound; the molar ratio of the hydroxyl-isocyanate compound to the tricyclic amino compound was 3:1; the structural formula of the hydroxyl-isocyanate compound is as follows: (3) Mix and react the tricyclic isocyanuric acid hydroxy compound and γ-isocyanate propyltriethoxysilane to obtain a functional silane coupling agent; the molar ratio of the tricyclic isocyanuric acid hydroxy compound and γ-isocyanate propyltriethoxysilane is 1:

3. (4) After mixing the functional silane coupling agent, water and acetic acid, let it stand, and then mix it with quartz fiber to react and obtain modified quartz fiber. (5) After mixing the functional silane coupling agent, water and acetic acid, let it stand, and then mix it with nano zirconium silicate to react and obtain modified nano zirconium silicate. (6) Modified quartz fiber, modified nano zirconium silicate, functional silane coupling agent, hydroxyl-modified polypropylene and polypropylene are melt-blended, extruded and granulated to obtain a mixture; hydroxyl-modified polypropylene is prepared by reacting chlorinated polypropylene, hydroxyl-containing aryl compound, hydroxyl protectant and catalyst. (7) The mixture is steam-foamed to obtain micro-expansion plastic filler.

2. The method for preparing the micro-expansion plastic filler as described in claim 1, characterized in that, In step (1), the mixing reaction is carried out under reflux conditions for 3 to 5 hours.

3. The method for preparing the micro-expansion plastic filler as described in claim 1, characterized in that, In step (2), a catalyst is added during the mixing reaction. The catalyst is triethylamine, and the mass of the catalyst is 1 to 1.5% of the mass of triglycidyl isocyanurate. The temperature of the mixing reaction in step (2) is 35 to 45°C, and the time is 3 to 5 hours.

4. The method for preparing the micro-expansion plastic filler as described in claim 1, characterized in that, The catalyst used in the mixing reaction in step (3) is triethylamine, and the mass of triethylamine is 1 to 1.5% of the mass of the tri-azosilane tricyclic isocyanuric acid hydroxy compound; the temperature of the mixing reaction is 70 to 90°C and the time is 18 to 24 hours.

5. The method for preparing the micro-expansion plastic filler as described in claim 1, characterized in that, In step (4), the mass ratio of quartz fiber, functional silane coupling agent, water and acetic acid is 1.5:1 to 1.2:100:2 to 2.5; the standing time is 45 to 65 minutes, and the mixing reaction time is 4 to 5 hours.

6. The method for preparing the micro-expansion plastic filler as described in claim 1, characterized in that, In step (5), the mass ratio of nano-zirconium silicate, functional silane coupling agent, water and acetic acid is 1.5:1.5~2:100:2~2.5; the standing time is 45~65min, and the mixing reaction time is 4~5h.

7. The method for preparing the micro-expansion plastic filler as described in claim 1, characterized in that, In step (6), the aryl compound containing hydroxyl groups is phenethyl alcohol, and the hydroxyl protecting agent is phosphoric acid. The preparation method of hydroxyl-modified polypropylene is as follows: after dissolving chlorinated polypropylene, a chlorinated polypropylene solution is obtained; the chlorinated polypropylene solution, phenethyl alcohol, phosphoric acid and boron trifluoride are mixed and reacted to obtain hydroxyl-modified polypropylene; the mass ratio of chlorinated polypropylene, phenethyl alcohol, phosphoric acid and boron trifluoride is 5:6.2:5:1.

5.

8. The method for preparing the micro-expansion plastic filler as described in claim 1, characterized in that, In step (6), the temperature of melt blending and extrusion is 180-190℃; the mass ratio of hydroxyl-modified polypropylene to polypropylene is 30-40:60-70; the mass of modified quartz fiber is 1.2-1.5% of the total mass of hydroxyl-modified polypropylene and polypropylene; and the mass of modified nano-zirconium silicate is 0.8-1.2% of the total mass of hydroxyl-modified polypropylene and polypropylene.

9. The method for preparing the micro-expansion plastic filler as described in claim 1, characterized in that, In step (7), when the steam is foamed, the steam pressure is 0.35-0.5 MPa and the ventilation time is 40-50 s.

10. A micro-expansion plastic filler prepared by the method described in any one of claims 1-9.

Images