Micro-expansive plastic filler and preparation method thereof

Abstract

The invention relates to a micro-expansive plastic filler and a preparation method thereof, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: reacting a silazane tricyclic amino compound with triglycidyl isocyanurate, then reacting with isocyanate propyl triethoxy silane to obtain a polysilane coupling agent, and then modifying linear quartz fibers and spherical nano zirconium silicate by using the silane coupling agent to obtain the high-temperature-resistant quartz fiber composite material. Carrying out melt extrusion granulation on the modified quartz fiber, the modified nano zirconium silicate, the hydroxyl modified polypropylene and the polypropylene, and finally carrying out steam foaming. The silatrane structure and the isocyanuric acid structure can provide support for foam pore formation, the rigid annular structure can provide steric hindrance for quartz fibers and zirconium silicate to avoid agglomeration, a functional silane coupling agent is added in the water vapor foaming process, a cross-linked net structure can be formed through hydrolysis, and the foam pore forming effect is improved. The cell stability and the heat-insulation and sound-insulation mechanical properties of the micro-expansion plastic filler are improved.

Description

Technical Field

[0001] The invention relates to a micro-expansion plastic filler and a preparation method thereof, belonging to the technical field of polymer materials. Background Art

[0002] Foam plastics have the advantages of light weight, heat insulation, cushioning, 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 are polyurethane foam plastics, polystyrene foam plastics, polyethylene foam plastics, and polypropylene foam plastics. In the foaming process of polyurethane foam, there are isocyanate residues that are harmful to the human body, and the foaming material cannot be recycled. In the process of polystyrene foaming, chlorofluorocarbon compounds or butane are usually used, which have an adverse effect on the environment, the product is difficult to degrade, and it is easy to form white pollution. Performance deviation of polyethylene foam plastics. Polypropylene foam plastics have good rigidity, heat resistance, low temperature resistance, dimensional stability, and energy absorption performance. Therefore, due to its excellent heat resistance, hygiene, heat insulation, and good environmental effects, polypropylene foam products are widely used and can play an important role in packaging, automobiles, construction and other fields.

[0003] At present, generally, expanded polypropylene beads are prepared by foaming polypropylene resin, and then the corresponding expanded polypropylene products are prepared by using the expanded polypropylene beads. In order to improve the mechanical properties of expanded foamed polypropylene, an appropriate amount of inorganic hard filler is usually added, but the inorganic hard filler has poor compatibility with the polypropylene matrix. While improving the mechanical properties of the material, it will affect the viscoelasticity of the polypropylene melt and the foaming process of the material, resulting in the degradation of the pore structure, thereby affecting the thermal insulation and sound insulation properties of the material. Summary of the invention

[0004] The purpose of the present invention is to provide a micro-expanded plastic filler and a preparation method thereof, which can solve the problem that the viscoelasticity of the polypropylene melt and the thermal insulation and sound insulation properties of the material deteriorate when inorganic fillers are used to modify polypropylene foam materials.

[0005] The present invention provides a method for preparing a micro-expandable plastic filler, comprising the following steps:

[0006] (1) Triisopropanolamine and γ-aminopropyltriethoxysilane in a molar ratio of 1:1 are mixed and reacted to obtain γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silatricyclo[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-silatricyclo[3,3,3,01,5]undecane and triglycidyl isocyanurate are mixed and reacted to obtain a silatricyclo-isocyanuric acid hydroxy compound; the molar ratio of the silatricycloamino compound to triglycidyl isocyanurate is 3:1; the structural formula of the silatricyclo-isocyanuric acid hydroxy compound is as follows:

[0009]

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

[0011] (4) mixing a functional silane coupling agent, water and acetic acid, leaving the mixture to stand, and then mixing the mixture with quartz fiber to react, thereby obtaining a modified quartz fiber;

[0012] (5) mixing a functional silane coupling agent, water and acetic acid, and then standing the mixture, and then mixing and reacting the mixture with nano zirconium silicate to obtain modified nano zirconium silicate;

[0013] (6) melt-blending, extruding and granulating the modified quartz fiber, modified nano zirconium silicate, functional silane coupling agent, hydroxyl-modified polypropylene and polypropylene to obtain a mixture; the hydroxyl-modified polypropylene is prepared by reacting chlorinated polypropylene, an aromatic compound containing a hydroxyl group, a hydroxyl protective agent and a catalyst;

[0014] (7) The mixed material is subjected to water vapor foaming to obtain a micro-expandable plastic filler.

[0015] Preferably, in step (1), the mixed 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 mixed reaction in step (3) is triethylamine, the mass of triethylamine is 1-1.5% of the mass of the silazotricyclo-isocyanuric acid hydroxy compound; the temperature of the mixed reaction is 70-90° C., and the time is 18-24 h.

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

[0020] Preferably, in step (6), the hydroxyl-containing aromatic compound is phenylethyl alcohol, and the hydroxyl protecting agent is phosphoric acid; the preparation method of hydroxyl-modified polypropylene is as follows: dissolving chlorinated polypropylene to obtain a chlorinated polypropylene solution; mixing the chlorinated polypropylene solution, phenylethyl alcohol, phosphoric acid and boron trifluoride to obtain hydroxyl-modified polypropylene; the mass ratio of chlorinated polypropylene, phenylethyl alcohol, 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 the modified quartz fiber is 1.2-1.5% of the total mass of hydroxyl-modified polypropylene and polypropylene, and the mass of the 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 water vapor is foamed, the water vapor pressure is 0.35 to 0.5 MPa and the ventilation time is 40 to 50 seconds.

[0023] The present invention provides a micro-expanding plastic filler, which is prepared by the preparation method of the micro-expanding plastic filler as described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention reacts a silane tricyclic amino compound with triglycidyl isocyanurate, and then reacts with isocyanate propyl triethoxysilane to obtain a polysilane coupling agent containing a silane tricyclic structure and an isocyanuric acid structure, and then uses the obtained functional silane coupling agent to modify linear quartz fiber and spherical nano zirconium silicate, and uses the modified quartz fiber and modified nano zirconium silicate to melt-extrude granulate with hydroxyl modified polypropylene and polypropylene, and finally performs water vapor foaming to obtain a micro-expanded plastic filler. The silane tricyclic structure and isocyanuric acid structure in the micro-expanded plastic filler can provide support for the formation of pores, and its rigid ring structure can provide steric hindrance for quartz fiber and nano zirconium silicate to avoid agglomeration. At the same time, the functional silane coupling agent is added during the water vapor foaming process, which can be further hydrolyzed to form a cross-linked network structure with hydroxyl polypropylene and nano filler, thereby improving the stability of the pores and the heat insulation and sound insulation mechanical properties of the micro-expanded plastic filler.

[0026] (2) During the foaming process of micro-expandable plastic filler, one-dimensional linear modified quartz fiber and three-dimensional spherical modified nano zirconium silicate can play a barrier and filling role. The linear modified quartz fiber can separate and block the spherical modified nano zirconium silicate, while the spherical modified nano zirconium silicate can hinder the linear modified quartz fiber from approaching and stacking, thereby making the one-dimensional linear modified quartz fiber and the three-dimensional spherical modified nano zirconium silicate evenly dispersed in the micro-expandable plastic filler. The two play a synergistic role. The surface-grafted functional silane coupling agent can further improve the steric hindrance between the quartz fiber and nano zirconium silicate, improve the compatibility with polypropylene, improve the foaming performance and the stability and uniformity of the pores, and thus improve the comprehensive performance of the micro-expandable plastic filler.

[0027] (3) The present invention uses a multifunctional coupling agent to modify nano zirconium silicate and quartz fiber, so that the heteroazosilicon tricyclic structure and isocyanuric acid structure can be evenly and firmly coated on the surface of the nano material, thereby improving the compatibility between the nano material and polypropylene and the barrier properties between the nano materials, improving the viscoelasticity of the polypropylene melt, and facilitating the foaming process and the stability of the pores. The experimental results show that the mixture prepared in the present invention has a smaller loss factor, indicating that the elastic response of the melt is faster. In addition, the experimental results show that the use of a functional silane coupling agent to modify nano zirconium silicate and quartz fiber and using both at the same time can significantly improve the elastic response of the material melt, reduce the viscous dissipation phenomenon, and help stabilize the pore structure of the material during foaming, thereby improving the comprehensive performance of the final expanded material.

[0028] (4) The present invention prepares micro-crosslinked fillers by modifying polypropylene and modified fillers with a coupling agent, and then mixes the prepared fillers with polypropylene and performs molding to obtain a composite material having a small thermal conductivity, large compressive strength, tensile strength, notched impact strength and bending strength, and good flame retardant and heat resistant properties, which has good application prospects. DETAILED DESCRIPTION

[0029] The following examples are intended to further illustrate 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-expandable plastic filler of this embodiment comprises the following steps:

[0032] (1) 25 mmol of triisopropanolamine and 25 mmol of γ-aminopropyltriethoxysilane were added to a reaction flask, heated under reflux for reaction for 3 h under stirring conditions, and ethanol generated by the reaction was removed by distillation under reduced pressure to obtain a tricyclic amino compound of azasilylamine, i.e., γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silatricyclo[3,3,3,01,5]undecane, having the following structural formula:

[0033]

[0034] (2) dissolving a silane tricyclic amino compound in dioxane to obtain a solution A with a mass fraction of 10%; dissolving triglycidyl isocyanurate in dioxane to obtain a solution B with a mass fraction of 15%; stirring solution A and solution B evenly, then adding triethylamine catalyst, heating to 35° C., stirring and reacting for 3 hours, and then distilling the system after the reaction under reduced pressure to remove the solvent and triethylamine to obtain a silane tricyclic-isocyanuric acid hydroxy compound; wherein the molar ratio of the silane tricyclic amino compound to triglycidyl isocyanurate is 3:1, and the mass of the triethylamine catalyst is 1% of the mass of triglycidyl isocyanurate; the structural formula of the silane tricyclic-isocyanuric acid hydroxy compound is as follows:

[0035]

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

[0037] (4) Adding a functional silane coupling agent, water and acetic acid into a reaction kettle, stirring evenly and standing for 45 minutes, then adding quartz fiber (the diameter of the quartz fiber is 3 to 5 μm) into the reaction kettle, stirring and reacting for 4 hours, filtering, washing, and drying to obtain a 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) adding a functional silane coupling agent, water and acetic acid into a reaction kettle, stirring evenly and standing for 45 minutes, then adding nano zirconium silicate into the reaction kettle, stirring and reacting for 4 hours, filtering, washing and drying 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) 5 g of chlorinated polypropylene (chlorine content of 37%, molecular weight of 180,000 to 200,000) was added to 30 mL of decahydronaphthalene, heated to 120° C. under stirring until the chlorinated polypropylene was dissolved, then cooled to 100° C., then 6.2 g of phenylethanol and 5 g of phosphoric acid were added to the chlorinated polypropylene solution, stirred for 30 min, then 1.5 g of boron trifluoride catalyst was added, and the reaction was continued at 100° C. with stirring for 2 h. The system after the reaction was cooled to room temperature and poured into 200 mL of 1% HCl ethanol solution, left to stand for 1 h, filtered, and the filter cake was washed with dilute hydrochloric acid, then washed with sodium bicarbonate solution, and finally washed with water until the filtrate was neutral. After vacuum drying, hydroxyl-modified polypropylene was obtained with a hydroxyl content of 6.5%.

[0040] (7) Adding modified quartz fiber, modified nano zirconium silicate, functional silane coupling agent (the molar amount of the functional silane coupling agent is 30% of the molar amount of hydroxyl groups in hydroxyl-modified polypropylene), hydroxyl-modified polypropylene and polypropylene (molecular weight of 120,000 to 150,000) into an extruder for melt blending, extrusion and granulation to obtain a mixture; wherein the temperature of melt blending and extrusion is 180° C.; 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) The mixture is placed in an autoclave, and then water vapor is filled into the autoclave at a constant temperature. The water vapor pressure is 0.35 MPa, and the ventilation time is 40 seconds. The water vapor in the autoclave is then quickly released. The mixture in the autoclave is then placed in air to allow air to enter the pores. The mixture is then left to stand for 10 hours. After the pores are shaped, a micro-expanded plastic filler is obtained.

[0042] Example 2

[0043] The preparation method of the micro-expandable plastic filler of this embodiment comprises the following steps:

[0044] (1) 25 mmol of triisopropanolamine and 25 mmol of γ-aminopropyltriethoxysilane were added to a reaction flask, heated under reflux for 4 h under stirring conditions, and ethanol generated by the reaction was removed by distillation under reduced pressure to obtain a tricyclic amino compound of azasilane, i.e., γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silatricyclo[3,3,3,01,5]undecane, having the following structural formula:

[0045]

[0046] (2) dissolving a tricyclic amino compound of azosilane in dioxane to obtain a solution A with a mass fraction of 12%; dissolving triglycidyl isocyanurate in dioxane to obtain a solution B with a mass fraction of 12%; stirring the solution A and the solution B evenly, then adding a triethylamine catalyst, heating to 40° C., stirring and reacting for 4 hours, and then distilling the system after the reaction under reduced pressure to remove the solvent and triethylamine to obtain a tricyclic amino compound of azosilane-isocyanuric acid hydroxyl compound; wherein the molar ratio of the tricyclic amino compound of azosilane to triglycidyl isocyanurate is 3:1, and the mass of the triethylamine catalyst is 1.2% of the mass of triglycidyl isocyanurate; the structural formula of the tricyclic amino compound of azosilane-isocyanuric acid hydroxyl compound is as follows:

[0047]

[0048] (3) Dissolving the silane tricyclic-isocyanuric acid hydroxy compound in dichloromethane to obtain a solution C with a mass fraction of 12%, then adding γ-isocyanate propyl triethoxysilane and a catalyst triethylamine to the solution C, heating to 80° C., stirring and reflux reaction for 20 hours, and removing the solvent and triethylamine by reduced pressure distillation to obtain a functional silane coupling agent; the molar ratio of the silane tricyclic-isocyanuric acid hydroxy compound to the γ-isocyanate propyl triethoxysilane is 1:3, and the mass of the triethylamine is 1.2% of the mass of the silane tricyclic-isocyanuric acid hydroxy compound.

[0049] (4) Adding a functional silane coupling agent, water and acetic acid into a reaction kettle, stirring evenly and standing for 50 minutes, then adding quartz fiber (the diameter of the quartz fiber is 3 to 5 μm) into the reaction kettle, stirring and reacting for 4.5 hours, filtering, washing, and drying 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) adding a functional silane coupling agent, water and acetic acid into a reaction kettle, stirring evenly and standing for 50 minutes, then adding nano zirconium silicate into the reaction kettle, stirring and reacting for 4.5 hours, filtering, washing and drying 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) 5 g of chlorinated polypropylene (chlorine content of 37%, molecular weight of 180,000 to 200,000) was added to 30 mL of decahydronaphthalene, heated to 120° C. under stirring until the chlorinated polypropylene was dissolved, then cooled to 100° C., then 6.2 g of phenylethanol and 5 g of phosphoric acid were added to the chlorinated polypropylene solution, stirred for 30 min, then 1.5 g of boron trifluoride catalyst was added, and the reaction was continued at 100° C. with stirring for 2 h. The system after the reaction was cooled to room temperature and poured into 200 mL of 1% HCl ethanol solution, left to stand for 1 h, filtered, and the filter cake was washed with dilute hydrochloric acid, then washed with sodium bicarbonate solution, and finally washed with water until the filtrate was neutral. After vacuum drying, hydroxyl-modified polypropylene was obtained with a hydroxyl content of 6.5%.

[0052] (7) Adding modified quartz fiber, modified nano zirconium silicate, functional silane coupling agent (the molar amount of the functional silane coupling agent is 32% of the molar amount of hydroxyl groups in hydroxyl-modified polypropylene), hydroxyl-modified polypropylene and polypropylene (molecular weight of 120,000 to 150,000) into an extruder for melt blending, extrusion and granulation to obtain a mixture; wherein the temperature of melt blending and extrusion is 185° C.; 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) The mixture is placed in an autoclave, and then water vapor is filled into the autoclave at a constant temperature. The water vapor pressure is 0.4 MPa and the ventilation time is 45 seconds. The water vapor in the autoclave is then quickly released. The mixture in the autoclave is then placed in air to allow air to enter the pores. The mixture is then left to stand for 11 hours. After the pores are shaped, a micro-expanded plastic filler is obtained.

[0054] Example 3

[0055] The preparation method of the micro-expandable plastic filler of this embodiment comprises the following steps:

[0056] (1) 25 mmol of triisopropanolamine and 25 mmol of γ-aminopropyltriethoxysilane were added to a reaction flask, heated under reflux for reaction for 5 h under stirring conditions, and ethanol generated by the reaction was removed by distillation under reduced pressure to obtain a tricyclic amino compound of azasilylamine, i.e., γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silatricyclo[3,3,3,01,5]undecane, having the following structural formula:

[0057]

[0058] (2) dissolving a silane tricyclic amino compound in dioxane to obtain a solution A with a mass fraction of 15%; dissolving triglycidyl isocyanurate in dioxane to obtain a solution B with a mass fraction of 10%; stirring solution A and solution B evenly, then adding triethylamine catalyst, heating to 45° C., stirring and reacting for 5 hours, and then distilling the system after the reaction under reduced pressure to remove the solvent and triethylamine to obtain a silane tricyclic-isocyanuric acid hydroxy compound; wherein the molar ratio of the silane tricyclic amino compound to triglycidyl isocyanurate is 3:1, and the mass of the triethylamine catalyst is 1.5% of the mass of triglycidyl isocyanurate; the structural formula of the silane tricyclic-isocyanuric acid hydroxy compound is as follows:

[0059]

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

[0061] (4) Adding a functional silane coupling agent, water and acetic acid into a reaction kettle, stirring evenly and standing for 65 minutes, then adding quartz fiber (the diameter of the quartz fiber is 3 to 5 μm) into the reaction kettle, stirring and reacting for 5 hours, filtering, washing, and drying to obtain a modified quartz fiber; wherein the mass ratio of the quartz fiber, the functional silane coupling agent, water and acetic acid is 1.5:1.2:100:2.5.

[0062] (5) adding a functional silane coupling agent, water and acetic acid into a reaction kettle, stirring evenly and standing for 65 minutes, then adding nano zirconium silicate into the reaction kettle, stirring and reacting for 5 hours, filtering, washing and drying 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) 5 g of chlorinated polypropylene (chlorine content of 37%, molecular weight of 180,000 to 200,000) was added to 30 mL of decahydronaphthalene, heated to 120° C. under stirring until the chlorinated polypropylene was dissolved, then cooled to 100° C., then 6.2 g of phenylethanol and 5 g of phosphoric acid were added to the chlorinated polypropylene solution, stirred for 30 min, then 1.5 g of boron trifluoride catalyst was added, and the reaction was continued at 100° C. with stirring for 2 h. The system after the reaction was cooled to room temperature and poured into 200 mL of 1% HCl ethanol solution, left to stand for 1 h, filtered, and the filter cake was washed with dilute hydrochloric acid, then washed with sodium bicarbonate solution, and finally washed with water until the filtrate was neutral. After vacuum drying, hydroxyl-modified polypropylene was obtained with a hydroxyl content of 6.5%.

[0064] (7) Adding modified quartz fiber, modified nano zirconium silicate, functional silane coupling agent (the molar amount of the functional silane coupling agent is 35% of the molar amount of hydroxyl groups in hydroxyl-modified polypropylene), hydroxyl-modified polypropylene and polypropylene (molecular weight of 120,000 to 150,000) into an extruder for melt blending, extrusion and granulation to obtain a mixture; wherein the temperature of melt blending and extrusion is 190° C.; the mass ratio of hydroxyl-modified polypropylene to 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) The mixture is placed in an autoclave, and then water vapor is filled into the autoclave at a constant temperature. The water vapor pressure is 0.5 MPa and the ventilation time is 50 seconds. The water vapor in the autoclave is then quickly released. The mixture in the autoclave is then placed in air to allow air to enter the pores. The mixture is then left to stand for 12 hours. After the pores are shaped, a micro-expanded plastic filler is obtained.

[0066] Comparative Example 1

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

[0068] Comparative Example 2

[0069] The difference between the preparation method of the micro-expandable plastic filler of this comparative example and the preparation method of the micro-expandable plastic filler of Example 1 is that in step (2) of the preparation method of the micro-expandable plastic filler of this comparative example, the tricyclic amino compound of heteroazosilane is replaced by amphetamine.

[0070] Comparative Example 3

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

[0072] Comparative Example 4

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

[0074] Comparative Example 5

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

[0076] Experimental Example 1

[0077] In order to investigate the rheological properties of the mixtures in the various embodiments and comparative examples, and further investigate their foaming effects, the loss factors of the mixtures prepared in step (7) of embodiments 1-3 and comparative examples 2-5 were tested at different shear frequencies at 178°C, and the results are shown in Table 1.

[0078] Table 1 Loss factor of mixture at different shear frequencies

[0079]

[0080] The loss factor is the phase difference between strain and stress of the melt under alternating shearing, which is greatly affected by stress and strain. The smaller the loss factor, the faster the elastic response of the melt. From the results in Table 1, it can be seen that the use of functional silane coupling agent to modify nano zirconium silicate and quartz fiber and use them together can significantly improve the elastic response of the material melt, reduce viscous dissipation, stabilize the pore structure of the material during foaming, and improve the comprehensive performance of the final expanded material.

[0081] Experimental Example 2

[0082] In order to evaluate the comprehensive performance of the micro-expanded plastic filler of each embodiment and comparative example, the micro-expanded plastic filler and polypropylene were mixed in a mass ratio of 1:1 and then molded to obtain test samples, and then the thermal conductivity, combustion performance, compression strength, tensile strength, notched impact strength and flexural strength of each sample were tested; wherein, the thermal conductivity was obtained by thermal conductivity instrument testing, the combustion performance was tested according to the method in standard GB / T8332-2008, and the test results were expressed as self-extinguishing time, the compression strength was tested according to the method in standard GBT8813-2008, the tensile strength was tested according to the method in standard GB / T 1040.2-2006, the notched impact strength was tested according to the method in standard GB / T 1843-2008, and the flexural strength was tested according to the method in standard GB / T 9341-2008. The test results of thermal conductivity, combustion performance, compression strength, tensile strength, notched impact strength and flexural strength of the materials of each embodiment and comparative example are shown in Table 2.

[0083] Table 1 Thermal conductivity, fuel efficiency, and thermal conductivity of the materials in the examples and comparative examples.

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

[0085]

[0086] It can be seen from Table 2 that according to Example 1 and Comparative Example 2, the tricyclic structure of heteroazosilicon can effectively improve the mechanical properties and thermal insulation properties of the micro-expanding plastic filler; according to Example 1 and Comparative Examples 3-4, it can be seen that when the modified nano zirconium silicate and modified quartz fiber in the present invention are used at the same time, the comprehensive performance of the micro-expanding plastic filler can be effectively improved. This may be because the one-dimensional linear modified quartz fiber and the three-dimensional spherical modified nano zirconium silicate can have a barrier and filling effect during the molding and foaming process of the micro-expanding plastic filler. The linear modified quartz fiber can separate and block the spherical modified nano zirconium silicate, while the spherical modified nano zirconium silicate can hinder the linear modified quartz fiber from approaching and stacking, thereby making the one-dimensional linear modified quartz fiber and the three-dimensional spherical modified nano zirconium silicate evenly dispersed in the micro-expanding plastic filler. The two play a synergistic role, and the surface-grafted functional silane coupling agent can further improve the steric hindrance between the quartz fiber and nano zirconium silicate, improve the compatibility with polypropylene, improve the foaming performance and bubble stability and uniformity, and thus improve the comprehensive performance of the micro-expanding plastic filler.

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

[0088] Table 3 Sound insulation of test samples obtained by molding using micro-expanded plastic fillers in various embodiments and comparative examples at different frequencies of sound waves

[0089]

[0090] As can be seen from Table 3, the micro-expanded plastic filler of the present invention can effectively improve the sound insulation performance of the polypropylene sheet, and has a higher sound insulation value in the sound wave frequency range of 400 to 200 Hz. Although the micro-expanded plastic fillers of Comparative Examples 1-5 can also play a sound insulation role, the sound insulation value in the sound wave frequency range of 400 to 200 Hz is significantly lower than that of the present invention. The above results show that the coupling agent modified polypropylene, fiber and zirconium silicate with a silazane tricyclic structure and an isocyanuric acid structure in the present invention can effectively improve the sound insulation performance of the material in the sound wave frequency range of 400 to 200 Hz.

Claims

1. A method for preparing a micro-expandable plastic filler, characterized in that: The following steps are involved: (1) Triisopropanolamine and γ-aminopropyltriethoxysilane in a molar ratio of 1:1 are mixed and reacted to obtain γ-aminopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silatricyclo[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-silatricyclo[3,3,3,01,5]undecane and triglycidyl isocyanurate are mixed and reacted to obtain a silatricyclo-isocyanuric acid hydroxy compound; the molar ratio of the silatricycloamino compound to triglycidyl isocyanurate is 3:1; the structural formula of the silatricyclo-isocyanuric acid hydroxy compound is as follows: (3) mixing a silane tricyclic-isocyanuric acid hydroxy compound and γ-isocyanate propyl triethoxy silane to obtain a functional silane coupling agent; the molar ratio of the silane tricyclic-isocyanuric acid hydroxy compound to the γ-isocyanate propyl triethoxy silane is 1:3; (4) mixing a functional silane coupling agent, water and acetic acid, leaving the mixture to stand, and then mixing the mixture with quartz fiber to react, thereby obtaining a modified quartz fiber; (5) mixing a functional silane coupling agent, water and acetic acid, and then standing the mixture, and then mixing and reacting the mixture with nano zirconium silicate to obtain modified nano zirconium silicate; (6) melt-blending, extruding and granulating the modified quartz fiber, modified nano zirconium silicate, functional silane coupling agent, hydroxyl-modified polypropylene and polypropylene to obtain a mixture; the hydroxyl-modified polypropylene is prepared by reacting chlorinated polypropylene, an aromatic compound containing a hydroxyl group, a hydroxyl protective agent and a catalyst; (7) The mixed material is subjected to water vapor foaming to obtain a micro-expandable plastic filler.

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

3. The method for preparing the micro-expandable plastic filler according to claim 1, characterized in that: During the mixed reaction in step (2), a catalyst is added, the catalyst is triethylamine, and the mass of the catalyst is 1-1.5% of the mass of triglycidyl isocyanurate; the temperature of the mixed reaction in step (2) is 35-45° C., and the time is 3-5 hours.

4. The method for preparing the micro-expandable plastic filler according to claim 1, characterized in that: The catalyst used in the mixed reaction in step (3) is triethylamine, the mass of which is 1 to 1.5% of the mass of the silazotricyclo-isocyanuric acid hydroxy compound; the temperature of the mixed reaction is 70 to 90° C., and the time is 18 to 24 hours.

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

6. The method for preparing the micro-expandable plastic filler according to 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 45-65 minutes, and the mixing reaction time is 4-5 hours.

7. The method for preparing the micro-expandable plastic filler according to claim 1, characterized in that: In step (6), the hydroxyl-containing aromatic compound is phenylethyl alcohol, and the hydroxyl protecting agent is phosphoric acid. The preparation method of hydroxyl-modified polypropylene is as follows: dissolving chlorinated polypropylene to obtain a chlorinated polypropylene solution; mixing the chlorinated polypropylene solution, phenylethyl alcohol, phosphoric acid and boron trifluoride to obtain hydroxyl-modified polypropylene; the mass ratio of chlorinated polypropylene, phenylethyl alcohol, phosphoric acid and boron trifluoride is 5:6.2:5:1.

5.

8. The method for preparing the micro-expandable plastic filler according to claim 1, characterized in that: 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 the modified quartz fiber is 1.2-1.5% of the total mass of the hydroxyl-modified polypropylene and polypropylene, and the mass of the modified nano zirconium silicate is 0.8-1.2% of the total mass of the hydroxyl-modified polypropylene and polypropylene.

9. The method for preparing the micro-expandable plastic filler according to claim 1, characterized in that: In step (7), when the water vapor is foaming, the water vapor pressure is 0.35 to 0.5 MPa and the ventilation time is 40 to 50 seconds.

10. A micro-expandable plastic filler prepared by the method for preparing a micro-expandable plastic filler according to any one of claims 1 to 9.

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