Calcium-based powder material for polypropylene film and method for preparing the same

Abstract

The application discloses a calcium-based powder material for polypropylene film and a preparation method thereof, and belongs to the technical field of powder materials. The calcium-based powder material for polypropylene film is formed by the "click chemistry" reaction of a modified calcium carbonate whisker with an azide group and an alkyne group POSS, the triazole ring is formed, the three-dimensional network structure is constructed on the surface of the calcium carbonate whisker, and the interface transfer is inhibited; meanwhile, the micrometer scale of the POSS and the calcium carbonate whisker forms hierarchical filling, and the rigidity and heat resistance of the PP are simultaneously improved; the triazole ring formed by the click chemistry enables the stress to be efficiently transmitted from the PP matrix to the whisker and the POSS network; the nanodispersion of the POSS fills the gaps between the whiskers and reduces stress concentration. Moreover, the triazole ring group formed by the azide group and the alkyne group has the characteristics of high-temperature carbonization, self-crosslinking of the alkenes network or the formation of aromatic rings by the cyclo-trimerization reaction under high-temperature conditions, the dense nano-structure protective layer is formed on the surface of the polypropylene material, the mass transfer heat insulation barrier is good, and the flame-retardant performance is good.

Description

Technical Field

[0001] This invention relates to the field of powder materials technology, and in particular to a calcium-based powder material for polypropylene films and its preparation method. Background Technology

[0002] Polypropylene film is widely used in packaging, agriculture and other fields due to its excellent mechanical properties, transparency and processing performance; calcium carbonate has been extensively studied as an inorganic filler in order to reduce costs and improve performance (such as rigidity, air permeability and thermal stability).

[0003] Calcium carbonate is widely available, inexpensive, non-toxic, and odorless, making it an environmentally friendly material. As a skeletal material, calcium carbonate can improve the mechanical properties, processing performance, and heat resistance of polypropylene. However, the surface of calcium carbonate contains numerous hydrophilic groups, resulting in poor compatibility with polypropylene. Furthermore, calcium carbonate is prone to molding, which negatively impacts the performance of polypropylene.

[0004] CN105348641A discloses a calcium carbonate-filled flame-retardant polypropylene material and its preparation method. The flame-retardant polypropylene material is composed of the following raw materials in parts by weight: 25-85 parts polypropylene resin, 10-60 parts calcium carbonate, 1-10 parts compounded flame retardant, 1-20 parts compatibilizer, 0.2-0.6 parts antioxidant, 0.2-1.0 parts lubricant, and 0.1-0.3 parts white mineral oil. The preparation method of the flame-retardant polypropylene material includes the following steps: 1) adding polypropylene resin and white mineral oil to a high-speed mixer and mixing evenly; 2) adding calcium carbonate, compounded flame retardant, compatibilizer, antioxidant, and lubricant to a high-speed mixer and mixing evenly; 3) adding the material from the high-speed mixer to a twin-screw extruder for melt extrusion granulation to obtain the calcium carbonate-filled flame-retardant polypropylene material. The flame-retardant polypropylene material of this invention has excellent flame-retardant properties, good mechanical properties, excellent processing performance, and low cost, but its mechanical properties need further improvement. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides a calcium-based powder material for polypropylene films and a method for preparing the same. The calcium-based powder material prepared by this method exhibits good dispersibility and processing fluidity in polypropylene films, and has good compatibility with polypropylene materials. It can significantly improve the mechanical properties of polypropylene films and improve their flame retardant properties.

[0006] The high aspect ratio of calcium carbonate whiskers gives them excellent mechanical properties in polypropylene materials. As a rigid skeleton, calcium carbonate whiskers effectively inhibit the deformation of polypropylene films. At the same time, when crack propagation encounters whiskers, it is deflected or branched, consuming more energy. During processing, an anisotropic reinforcing network is formed. The smooth surface and moderate aspect ratio of calcium carbonate whiskers reduce mechanical interlocking between particles, improve flowability, and reduce energy consumption during injection molding and extrusion. Calcium carbonate whiskers can reduce the shrinkage rate and coefficient of thermal expansion of polypropylene, and reduce product warping.

[0007] A method for preparing a calcium-based powder material for polypropylene films includes the following steps:

[0008] S1. Calcium carbonate whiskers are treated with a coupling agent to obtain pretreated calcium carbonate whiskers.

[0009] S2. Azide-modified calcium carbonate whiskers were prepared using glycidyl methacrylate, acryloyl chloride, styrene, and pretreated calcium carbonate whiskers as raw materials and azobisisobutyronitrile as an initiator.

[0010] S3. Using 4-ethynylphenylacetic acid and octa-aminophenyl-POSS as raw materials, alkynyl-containing POSS was prepared.

[0011] S4. The azide-modified calcium carbonate whiskers and alkynyl POSS prepared above undergo a click chemical reaction under the action of cuprous bromide and pentamethyldiethylenetriamine to prepare calcium-based powder material for polypropylene film.

[0012] However, as an inorganic filler, calcium carbonate whiskers have a large number of hydrophilic groups on their surface, which makes them incompatible with polypropylene materials. They also have poor dispersibility and are prone to agglomeration, which affects their mechanical properties and can even cause cracks.

[0013] Based on the above, calcium carbonate whiskers are treated simultaneously with 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane. This not only improves the surface properties of calcium carbonate whiskers but also introduces new active groups. On the one hand, this reduces the surface energy of calcium carbonate whiskers, and on the other hand, it improves their dispersibility in polypropylene materials, thereby improving their mechanical properties, stability, and other characteristics. Azide-modified calcium carbonate whiskers were prepared using glycidyl methacrylate, acryloyl chloride, and styrene as raw materials and a coupling agent was introduced. The azide-modified calcium carbonate whiskers also contain epoxy groups, benzene rings, and ester groups, which significantly improve the interfacial bonding between the calcium carbonate whiskers and polypropylene, reducing phase separation. The styrene segments are nonpolar and highly compatible with the polypropylene molecular chains, enhancing interfacial bonding through molecular chain entanglement. The ester groups introduced by the acryloyl chloride generate dipole-dipole interactions with the tertiary carbon atoms in PP. The grafted polymer forms a spatial barrier on the surface of the calcium carbonate whiskers, preventing the whiskers from approaching each other and improving mechanical strength.

[0014] Alkyne-containing POSS was prepared using 4-ethynylphenylacetic acid and octa-aminophenyl-POSS as raw materials. Under the action of cuprous bromide and pentamethyldiethylenetriamine, it underwent a "click chemistry" reaction with azide-modified calcium carbonate whiskers to form triazole rings, constructing a three-dimensional network structure on the surface of the calcium carbonate whiskers and inhibiting interface transfer. Simultaneously, POSS and calcium carbonate whiskers formed a hierarchical filling effect at the micron scale, improving the rigidity and heat resistance of PP. The triazole rings formed by click chemistry efficiently transferred stress from the PP matrix to the whiskers and POSS network. The nano-dispersion of POSS filled the voids between whiskers, reducing stress concentration. Furthermore, the triazole ring groups formed by the azide and alkynyl groups simultaneously self-crosslinked at high temperatures to form an olefin network or formed aromatic rings through cyclic trimerization, exhibiting high-temperature charring characteristics. This resulted in a dense nanostructured protective layer on the surface of the polypropylene material, providing excellent mass transfer and thermal insulation barriers, and exhibiting good flame retardant properties.

[0015] A further preferred method for preparing a calcium-based powder material for polypropylene films includes the following steps:

[0016] S1. Add calcium carbonate whiskers and coupling agent to 50-70wt% ethanol aqueous solution, mix evenly, heat to 60-70℃ for 1-5h, after the reaction is completed, centrifuge, wash and dry to obtain pretreated calcium carbonate whiskers.

[0017] S2. Mix 0.1-0.8 parts by weight of glycidyl methacrylate, 0.01-0.2 parts by weight of acryloyl chloride, 0.01-0.3 parts by weight of styrene, 1-3 parts by weight of pretreated calcium carbonate whiskers, and 0.001-0.02 parts by weight of azobisisobutyronitrile evenly, and treat at 60-70℃ for 1-6 hours. After the reaction is completed, centrifuge, wash, and dry to obtain azide-modified calcium carbonate whiskers.

[0018] S3. Add 1-4 parts by weight of 4-ethynylphenylacetic acid and 3-5 parts by weight of octa-p-aminophenyl-POSS to 100-200 parts by weight of dimethyl sulfoxide and mix well. Then add 1-3 parts by weight of 1-hydroxybenzotriazole and 5-8 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride. Stir at room temperature under a nitrogen atmosphere for 24-48 hours. After the reaction is completed, concentrate, precipitate, wash and dry to obtain alkynyl-containing POSS.

[0019] S4. Add 1-3 parts by weight of the azide-modified calcium carbonate whiskers prepared above and 0.01-0.5 parts by weight of alkynyl POSS to 30-50 parts by weight of N,N-dimethylformamide and mix evenly. Add 0.01-0.4 parts by weight of cuprous bromide and 0.01-0.45 parts by weight of pentamethyldiethylenetriamine. React at 40-60°C for 24 hours under a nitrogen atmosphere. After the reaction is completed, wash and dry to obtain calcium-based powder material for polypropylene film.

[0020] In step S1, the mass ratio of calcium carbonate whiskers to coupling agent is 1:(0.1-0.6); the mass ratio of calcium carbonate whiskers to ethanol aqueous solution is 1:(10-20).

[0021] The coupling agent is at least one of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane.

[0022] The beneficial effects of this invention are:

[0023] 1. Compared with existing technologies, alkynyl POSS is prepared using 4-ethynylphenylacetic acid and octa-aminophenyl-POSS as raw materials. Under the action of cuprous bromide and pentamethyldiethylenetriamine, it undergoes a "click chemistry" reaction with azide-modified calcium carbonate whiskers to form triazole rings, constructing a three-dimensional network structure on the surface of calcium carbonate whiskers and inhibiting interface transfer. At the same time, POSS and calcium carbonate whiskers form a hierarchical filling at the micron scale, which improves the rigidity and heat resistance of PP. The triazole rings formed by click chemistry enable stress to be efficiently transferred from the PP matrix to the whiskers and POSS network. The nano-dispersion of POSS fills the gaps between whiskers and reduces stress concentration.

[0024] 2. Compared with existing technologies, the triazole ring groups formed by azide and alkynyl groups can form an olefin network through self-crosslinking or an aromatic ring through cyclic trimerization under high temperature conditions. This has the characteristic of high-temperature char formation and forms a dense nanostructure protective layer on the surface of polypropylene materials, which has a good mass transfer and heat insulation barrier and good flame retardant properties. Detailed Implementation

[0025] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0026] Description of some of the raw materials used in the embodiments of this invention:

[0027] The method for preparing calcium carbonate whiskers used in the example is as follows: 20 mL of water and 80 mL of triethanolamine are mixed evenly and ultrasonically treated for 30 min. Then, 2.78 g of anhydrous calcium chloride and 10.5 g of urea are added and mixed evenly to obtain a mixture. The mixture is then transferred to a reaction vessel lined with polytetrafluoroethylene and reacted at 120 °C for 6 h. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain calcium carbonate whiskers.

[0028] Octaaminophenyl-POSS, CAS: 518359-82-5, purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0029] Other raw materials not mentioned are all common raw materials. The above content is only for the purpose of illustrating the present invention and should not be construed as a strict limitation of the present invention. Those skilled in the art can directly purchase the same / similar raw materials from the market or prepare them themselves.

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] A method for preparing a calcium-based powder material for polypropylene films includes the following steps:

[0033] S1. Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent to a 70 wt% ethanol aqueous solution and mix evenly. Heat to 70°C for 3 hours. After the reaction is completed, centrifuge, wash and dry to obtain pretreated calcium carbonate whiskers. The coupling agent is composed of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane mixed in a mass ratio of 1:1.

[0034] S2. Mix 0.8 parts by weight of glycidyl methacrylate, 0.2 parts by weight of acryloyl chloride, 0.3 parts by weight of styrene, 3 parts by weight of pretreated calcium carbonate whiskers, and 0.02 parts by weight of azobisisobutyronitrile evenly, treat at 70°C for 5 hours, and after the reaction is completed, centrifuge, wash and dry to obtain azide-modified calcium carbonate whiskers.

[0035] S3. Add 4 parts by weight of 4-ethynylphenylacetic acid and 5 parts by weight of octa-p-aminophenyl-POSS to 200 parts by weight of dimethyl sulfoxide and mix well. Then add 3 parts by weight of 1-hydroxybenzotriazole and 8 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride. Stir at room temperature for 45 h under nitrogen atmosphere. After the reaction is completed, concentrate, precipitate, wash and dry to obtain alkynyl-containing POSS.

[0036] S4. Add 3 parts by weight of the azide-modified calcium carbonate whiskers prepared above and 0.5 parts by weight of alkynyl POSS to 50 parts by weight of N,N-dimethylformamide and mix evenly. Add 0.4 parts by weight of cuprous bromide and 0.45 parts by weight of pentamethyldiethylenetriamine. React at 60°C for 24 hours under a nitrogen atmosphere. After the reaction is completed, wash and dry to obtain calcium-based powder material for polypropylene film.

[0037] Example 2

[0038] A method for preparing a calcium-based powder material for polypropylene films includes the following steps: adding 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent to a 70 wt% ethanol aqueous solution and mixing evenly, heating to 70°C for 3 hours, centrifuging, washing, and drying after the reaction to obtain the calcium-based powder material for polypropylene films; wherein the coupling agent is composed of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane mixed in a mass ratio of 1:1.

[0039] Example 3

[0040] A method for preparing a calcium-based powder material for polypropylene films includes the following steps:

[0041] S1. Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent to a 70 wt% ethanol aqueous solution and mix evenly. Heat to 70°C for 3 hours. After the reaction is completed, centrifuge, wash and dry to obtain pretreated calcium carbonate whiskers. The coupling agent is composed of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane mixed in a mass ratio of 1:1.

[0042] S2. Mix 0.8 parts by weight of glycidyl methacrylate, 0.2 parts by weight of acryloyl chloride, 0.3 parts by weight of styrene, 3 parts by weight of pretreated calcium carbonate whiskers, and 0.02 parts by weight of azobisisobutyronitrile evenly, treat at 70°C for 5 hours, centrifuge, wash and dry after the reaction to obtain calcium-based powder material for polypropylene film.

[0043] Example 4

[0044] A method for preparing a calcium-based powder material for polypropylene films includes the following steps:

[0045] S1. Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent to a 70 wt% ethanol aqueous solution and mix evenly. Heat to 70°C for 3 hours. After the reaction is completed, centrifuge, wash and dry to obtain pretreated calcium carbonate whiskers. The coupling agent is composed of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane mixed in a mass ratio of 1:1.

[0046] S2. Mix 0.8 parts by weight of glycidyl methacrylate, 0.2 parts by weight of acryloyl chloride, 0.3 parts by weight of styrene, 3 parts by weight of pretreated calcium carbonate whiskers, and 0.02 parts by weight of azobisisobutyronitrile evenly, treat at 70°C for 5 hours, and after the reaction is completed, centrifuge, wash and dry to obtain azide-modified calcium carbonate whiskers.

[0047] S3. Add 3 parts by weight of the azide-modified calcium carbonate whiskers prepared above and 0.5 parts by weight of octa-aminophenyl-POSS to 50 parts by weight of N,N-dimethylformamide and mix evenly. Add 0.4 parts by weight of cuprous bromide and 0.45 parts by weight of pentamethyldiethylenetriamine. React at 60°C for 24 hours under a nitrogen atmosphere. After the reaction is completed, wash and dry to obtain calcium-based powder material for polypropylene film.

[0048] Example 5

[0049] A method for preparing a calcium-based powder material for polypropylene films includes the following steps:

[0050] S1. Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent to a 70 wt% ethanol aqueous solution and mix evenly. Heat to 70°C for 3 hours. After the reaction is completed, centrifuge, wash and dry to obtain pretreated calcium carbonate whiskers. The coupling agent is composed of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane mixed in a mass ratio of 1:1.

[0051] S2. Add 4 parts by weight of 4-ethynylphenylacetic acid and 5 parts by weight of octa-aminophenyl-POSS to 200 parts by weight of dimethyl sulfoxide and mix well. Then add 3 parts by weight of 1-hydroxybenzotriazole and 8 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride. Stir at room temperature for 45 h under nitrogen atmosphere. After the reaction is completed, concentrate, precipitate, wash and dry to obtain alkynyl-containing POSS.

[0052] S3. Add 3 parts by weight of the pretreated calcium carbonate whiskers prepared above and 0.5 parts by weight of alkynyl POSS to 50 parts by weight of N,N-dimethylformamide and mix evenly. Add 0.4 parts by weight of cuprous bromide and 0.45 parts by weight of pentamethyldiethylenetriamine. React at 60°C for 24 hours under a nitrogen atmosphere. After the reaction is completed, wash and dry to obtain calcium-based powder material for polypropylene film.

[0053] Example 6

[0054] A method for preparing a calcium-based powder material for polypropylene film includes the following steps: adding 3 parts by weight of calcium carbonate whiskers and 0.5 parts by weight of octa-aminophenyl-POSS to 50 parts by weight of N,N-dimethylformamide and mixing evenly; adding 0.4 parts by weight of cuprous bromide and 0.45 parts by weight of pentamethyldiethylenetriamine; reacting at 60°C for 24 hours under a nitrogen atmosphere; after the reaction is completed, washing and drying to obtain the calcium-based powder material for polypropylene film.

[0055] Application Example 1

[0056] A method for preparing a polypropylene film involves uniformly mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yi'en Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride-grafted polypropylene (brand name 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearamide, and 15 parts by weight of the polypropylene film prepared in Example 1 with calcium-based powder material. The mixture is then fed into an extruder via a feeding device and heated to melt into a viscous liquid state. After filtration, the mixture is then deposited into a die. The material is extruded from the head, with the melt temperature controlled at 225℃. The extruded melt is cooled with 20℃ cooling water to form a cast sheet. The cast sheet is first longitudinally stretched, with a preheating temperature of 130℃, a stretching temperature of 100℃, a stretching ratio of 5.5 times, and a setting temperature of 90℃. Then it is transversely stretched, with a preheating temperature of 165℃, a stretching temperature of 155℃, a stretching ratio of 6.2 times, and a setting temperature of 110℃. Finally, it enters the traction machine, with the traction roller temperature at 30℃, and is wound up to obtain a polypropylene film.

[0057] Application Example 2

[0058] A method for preparing a polypropylene film involves uniformly mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yi'en Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride-grafted polypropylene (brand name 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearamide, and 15 parts by weight of the polypropylene film prepared in Example 2 with calcium-based powder material. The mixture is then fed into an extruder via a feeding device and heated to melt into a viscous liquid state. After filtration, the mixture is then deposited into a die. The material is extruded from the head, with the melt temperature controlled at 225℃. The extruded melt is cooled with 20℃ cooling water to form a cast sheet. The cast sheet is first longitudinally stretched, with a preheating temperature of 130℃, a stretching temperature of 100℃, a stretching ratio of 5.5 times, and a setting temperature of 90℃. Then it is transversely stretched, with a preheating temperature of 165℃, a stretching temperature of 155℃, a stretching ratio of 6.2 times, and a setting temperature of 110℃. Finally, it enters the traction machine, with the traction roller temperature at 30℃, and is wound up to obtain a polypropylene film.

[0059] Application Example 3

[0060] A method for preparing a polypropylene film involves uniformly mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yi'en Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride-grafted polypropylene (brand name 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearamide, and 15 parts by weight of the polypropylene film prepared in Example 3 with calcium-based powder material. The mixture is then fed into an extruder via a feeding device and heated to melt into a viscous liquid state. After filtration, the mixture is then deposited into a die. The material is extruded from the head, with the melt temperature controlled at 225℃. The extruded melt is cooled with 20℃ cooling water to form a cast sheet. The cast sheet is first longitudinally stretched, with a preheating temperature of 130℃, a stretching temperature of 100℃, a stretching ratio of 5.5 times, and a setting temperature of 90℃. Then it is transversely stretched, with a preheating temperature of 165℃, a stretching temperature of 155℃, a stretching ratio of 6.2 times, and a setting temperature of 110℃. Finally, it enters the traction machine, with the traction roller temperature at 30℃, and is wound up to obtain a polypropylene film.

[0061] Application Example 4

[0062] A method for preparing a polypropylene film involves uniformly mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yi'en Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride-grafted polypropylene (brand name 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearamide, and 15 parts by weight of the polypropylene film prepared in Example 4 with calcium-based powder material. The mixture is then fed into an extruder via a feeding device and heated to melt into a viscous liquid state. After filtration, the mixture is then deposited into a die. The material is extruded from the head, with the melt temperature controlled at 225℃. The extruded melt is cooled with 20℃ cooling water to form a cast sheet. The cast sheet is first longitudinally stretched, with a preheating temperature of 130℃, a stretching temperature of 100℃, a stretching ratio of 5.5 times, and a setting temperature of 90℃. Then it is transversely stretched, with a preheating temperature of 165℃, a stretching temperature of 155℃, a stretching ratio of 6.2 times, and a setting temperature of 110℃. Finally, it enters the traction machine, with the traction roller temperature at 30℃, and is wound up to obtain a polypropylene film.

[0063] Application Example 5

[0064] A method for preparing a polypropylene film involves uniformly mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yi'en Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride-grafted polypropylene (brand name 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearamide, and 15 parts by weight of the polypropylene film prepared in Example 5 with calcium-based powder material. The mixture is then fed into an extruder via a feeding device and heated to melt into a viscous liquid state. After filtration, the mixture is then deposited into a die. The material is extruded from the head, with the melt temperature controlled at 225℃. The extruded melt is cooled with 20℃ cooling water to form a cast sheet. The cast sheet is first longitudinally stretched, with a preheating temperature of 130℃, a stretching temperature of 100℃, a stretching ratio of 5.5 times, and a setting temperature of 90℃. Then it is transversely stretched, with a preheating temperature of 165℃, a stretching temperature of 155℃, a stretching ratio of 6.2 times, and a setting temperature of 110℃. Finally, it enters the traction machine, with the traction roller temperature at 30℃, and is wound up to obtain a polypropylene film.

[0065] Application Example 6

[0066] A method for preparing a polypropylene film involves uniformly mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yi'en Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride-grafted polypropylene (brand name 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearamide, and 15 parts by weight of the polypropylene film prepared in Example 6 with calcium-based powder material. The mixture is then fed into an extruder via a feeding device and heated to melt into a viscous liquid state. After filtration, the mixture is then deposited into a die. The material is extruded from the head, with the melt temperature controlled at 225℃. The extruded melt is cooled with 20℃ cooling water to form a cast sheet. The cast sheet is first longitudinally stretched, with a preheating temperature of 130℃, a stretching temperature of 100℃, a stretching ratio of 5.5 times, and a setting temperature of 90℃. Then it is transversely stretched, with a preheating temperature of 165℃, a stretching temperature of 155℃, a stretching ratio of 6.2 times, and a setting temperature of 110℃. Finally, it enters the traction machine, with the traction roller temperature at 30℃, and is wound up to obtain a polypropylene film.

[0067] Application Example 7

[0068] A method for preparing a polypropylene film involves uniformly mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yi'en Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride-grafted polypropylene (brand name: 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearamide, and 15 parts by weight of calcium carbonate whiskers. The mixture is fed into an extruder via a feeding device and heated to a viscous state. After filtration, the mixture is extruded through a die, with the melt temperature controlled at 225°C. The extruded melt is cooled with 20°C cooling water to form a cast sheet. The cast sheet is first longitudinally stretched at a preheating temperature of 130°C, a stretching temperature of 100°C, a stretch ratio of 5.5 times, and a setting temperature of 90°C. Then, it is transversely stretched at a preheating temperature of 165°C, a stretching temperature of 155°C, a stretch ratio of 6.2 times, and a setting temperature of 110°C. Finally, the film is fed into a traction machine with a traction roller temperature of 30°C and wound up to obtain the polypropylene film.

[0069] Test Example 1

[0070] The longitudinal and transverse tensile strengths of polypropylene films prepared in accordance with the corresponding test cases of GB / T10003-2008 "Test Methods for Tensile Properties of Plastic Films" were determined.

[0071] Table 1 Mechanical Performance Test Results

[0072] Longitudinal tensile strength / MPa Transverse tensile strength / MPa Application Example 1 164 231 Application Example 2 109 165 Application Example 3 128 187 Application Example 4 145 203 Application Example 5 152 218 Application Example 6 93 144 Application Example 7 71 95

[0073] As shown in Table 1, by comparing Application Example 7 with Application Example 2, it can be found that the polypropylene film treated with calcium carbonate whiskers simultaneously by 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane in Application Example 2 has good mechanical properties. In addition to improving the surface properties of calcium carbonate whiskers, 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane introduce new active groups, which on the one hand reduce the surface energy of calcium carbonate whiskers, and on the other hand improve their dispersibility in polypropylene materials, thereby improving their mechanical properties, stability and other characteristics.

[0074] Comparing Application Example 1 with Application Examples 2-7, it was found that in Application Example 1, 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane were used to treat calcium carbonate whiskers simultaneously. In addition to improving the surface properties of calcium carbonate whiskers, new active groups were introduced. On the one hand, the surface energy of calcium carbonate whiskers was reduced, and on the other hand, its dispersibility in polypropylene materials was improved, thereby improving its mechanical properties, stability and other characteristics. Azide-modified calcium carbonate whiskers were prepared using glycidyl methacrylate, acryloyl chloride, and styrene as raw materials and a coupling agent was introduced. The azide-modified calcium carbonate whiskers also contain epoxy groups, benzene rings, and ester groups, which significantly improve the interfacial bonding between the calcium carbonate whiskers and polypropylene, reducing phase separation. The styrene segments are nonpolar and highly compatible with the polypropylene molecular chains, enhancing interfacial bonding through molecular chain entanglement. The ester groups introduced by the acryloyl chloride generate dipole-dipole interactions with the tertiary carbon atoms in PP. The grafted polymer forms a spatial barrier on the surface of the calcium carbonate whiskers, preventing the whiskers from approaching each other and improving mechanical strength. Alkyne-containing POSS was prepared using 4-ethynylphenylacetic acid and octa-aminophenyl-POSS as raw materials. Under the action of cuprous bromide and pentamethyldiethylenetriamine, it underwent a "click chemistry" reaction with azide-modified calcium carbonate whiskers to form triazole rings, constructing a three-dimensional network structure on the surface of the calcium carbonate whiskers and inhibiting interface transfer. Simultaneously, POSS and calcium carbonate whiskers formed a hierarchical filling effect at the micron scale, improving the rigidity and heat resistance of PP. The triazole rings formed by the click chemistry enabled efficient stress transfer from the PP matrix to the whiskers and the POSS network. The nano-dispersion of POSS filled the voids between whiskers, reducing stress concentration.

[0075] Test Example 2

[0076] The impact breakage quality of polypropylene film prepared in accordance with the corresponding test cases of GB / T9639.1-2008 "Test Method for Impact Resistance of Plastic Films and Sheets" was tested.

[0077] Table 2 Impact Failure Quality Test Results

[0078] Impact failure mass at 25℃ / g Application Example 1 511 Application Example 2 421 Application Example 3 437 Application Example 4 475 Application Example 5 493 Application Example 6 410 Application Example 7 384

[0079] As shown in Table 2, the polypropylene film prepared using Example 1 exhibits good toughness. This may be because alkynyl POSS was prepared using 4-ethynylphenylacetic acid and octa-aminophenyl-POSS as raw materials. Under the action of cuprous bromide and pentamethyldiethylenetriamine, it underwent a "click chemistry" reaction with azide-modified calcium carbonate whiskers to form triazole rings, constructing a three-dimensional network structure on the surface of the calcium carbonate whiskers and inhibiting interface transfer. At the same time, POSS and calcium carbonate whiskers form a hierarchical filling at the micron scale, which improves the rigidity and heat resistance of PP. The triazole rings formed by the click chemistry enable the stress to be efficiently transferred from the PP matrix to the whiskers and the POSS network. The nano-dispersion of POSS fills the gaps between the whiskers, reducing stress concentration.

[0080] Test Example 3

[0081] The vertical burning performance was tested in accordance with the vertical burning test in GB / T 2408-2008 "Determination of Burning Performance of Plastics - Horizontal and Vertical Methods".

[0082] Table 3 Flame retardant performance test results

[0083] Vertical burning / (UL94 1.6mm) Application Example 1 V-0 Application Example 2 V-2 Application Example 3 V-1 Application Example 4 V-1 Application Example 5 V-1 Application Example 6 V-2 Application Example 7 V-2

[0084] This invention utilizes the triazole ring groups formed by azide and alkynyl groups to form an olefin network through self-crosslinking under high temperature conditions or to form an aromatic ring through cyclic trimerization, which has the characteristic of high-temperature char formation. This forms a dense nanostructure protective layer on the surface of polypropylene material, which has a good mass transfer and heat insulation barrier and good flame retardant properties.

[0085] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a calcium-based powder material for polypropylene films, characterized in that: A calcium-based powder material for polypropylene film was prepared by a click chemical reaction of azide-modified calcium-based material and alkynyl-containing POSS under the action of cuprous bromide and pentamethyldiethylenetriamine. The method for preparing the azidated modified calcium-based material is to use glycidyl methacrylate, acryloyl chloride, styrene, and pretreated calcium-based material as raw materials, and prepare azidated modified calcium carbonate whiskers under the action of an initiator. The method for preparing the alkynyl-containing POSS is to use 4-ethynylphenylacetic acid and octa-aminophenyl-POSS as raw materials to prepare the alkynyl-containing POSS. The method for preparing the pretreated calcium-based material is to treat the calcium-based material with a coupling agent to obtain the pretreated calcium-based material; The coupling agent is composed of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane in a mass ratio of 1:

1. The calcium-based material is calcium carbonate whiskers.

2. The method for preparing calcium-based powder material for polypropylene films as described in claim 1, characterized in that: The initiator is azobisisobutyronitrile.

3. The method for preparing calcium-based powder material for polypropylene films as described in claim 1, characterized in that: The method for preparing the calcium carbonate whiskers is as follows: water and triethanolamine are mixed evenly and ultrasonically treated, then anhydrous calcium chloride and urea are added and mixed evenly to obtain a mixture. The mixture is then transferred to a reaction vessel lined with polytetrafluoroethylene for reaction. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain calcium carbonate whiskers.

4. The method for preparing calcium-based powder material for polypropylene films as described in claim 1, characterized in that: Includes the following steps: S1. Add calcium carbonate whiskers and coupling agent to 50-70wt% ethanol aqueous solution, mix evenly, heat to 60-70℃ for 1-5h, after the reaction is completed, centrifuge, wash and dry to obtain pretreated calcium carbonate whiskers. S2. Mix 0.1-0.8 parts by weight of glycidyl methacrylate, 0.01-0.2 parts by weight of acryloyl chloride, 0.01-0.3 parts by weight of styrene, 1-3 parts by weight of pretreated calcium carbonate whiskers, and 0.001-0.02 parts by weight of azobisisobutyronitrile evenly, and treat at 60-70℃ for 1-6 hours. After the reaction is completed, centrifuge, wash, and dry to obtain azide-modified calcium carbonate whiskers. S3. Add 1-4 parts by weight of 4-ethynylphenylacetic acid and 3-5 parts by weight of octa-p-aminophenyl-POSS to 100-200 parts by weight of dimethyl sulfoxide and mix well. Then add 1-3 parts by weight of 1-hydroxybenzotriazole and 5-8 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride. Stir at room temperature under a nitrogen atmosphere for 24-48 hours. After the reaction is completed, concentrate, precipitate, wash and dry to obtain alkynyl-containing POSS. S4. Add 1-3 parts by weight of the azide-modified calcium carbonate whiskers prepared above and 0.01-0.5 parts by weight of alkynyl POSS to 30-50 parts by weight of N,N-dimethylformamide and mix evenly. Add 0.01-0.4 parts by weight of cuprous bromide and 0.01-0.45 parts by weight of pentamethyldiethylenetriamine. React at 40-60°C for 24 hours under a nitrogen atmosphere. After the reaction is completed, wash and dry to obtain calcium-based powder material for polypropylene film.

5. A calcium-based powder material for polypropylene films, characterized in that: It is prepared by the preparation method described in any one of claims 1-4.

6. A method for preparing a calcium-based powder material for polypropylene films, characterized in that, Includes the following steps: S1. Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent to a 70 wt% ethanol aqueous solution and mix evenly. Heat to 70°C for 3 hours. After the reaction is completed, centrifuge, wash and dry to obtain pretreated calcium carbonate whiskers. The coupling agent is composed of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane mixed in a mass ratio of 1:

1. S2. Mix 0.8 parts by weight of glycidyl methacrylate, 0.2 parts by weight of acryloyl chloride, 0.3 parts by weight of styrene, 3 parts by weight of pretreated calcium carbonate whiskers, and 0.02 parts by weight of azobisisobutyronitrile evenly, treat at 70°C for 5 hours, and after the reaction is completed, centrifuge, wash and dry to obtain azide-modified calcium carbonate whiskers. S3. Add 4 parts by weight of 4-ethynylphenylacetic acid and 5 parts by weight of octa-p-aminophenyl-POSS to 200 parts by weight of dimethyl sulfoxide and mix well. Then add 3 parts by weight of 1-hydroxybenzotriazole and 8 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride. Stir at room temperature for 45 h under nitrogen atmosphere. After the reaction is completed, concentrate, precipitate, wash and dry to obtain alkynyl-containing POSS. S4. Add 3 parts by weight of the azide-modified calcium carbonate whiskers prepared above and 0.5 parts by weight of alkynyl POSS to 50 parts by weight of N,N-dimethylformamide and mix evenly. Add 0.4 parts by weight of cuprous bromide and 0.45 parts by weight of pentamethyldiethylenetriamine. React at 60°C for 24 hours under a nitrogen atmosphere. After the reaction is completed, wash and dry to obtain calcium-based powder material for polypropylene film.