Calcium-based powder material for polypropylene film and preparation method of calcium-based powder material

Abstract

The invention discloses a calcium-based powder material for a polypropylene film and a preparation method of the calcium-based powder material, and belongs to the technical field of powder. According to the calcium-based powder material for the polypropylene film, alkynyl-containing POSS and azidation modified calcium carbonate whiskers are subjected to a click chemistry reaction to form a triazole ring, a three-dimensional network structure is constructed on the surfaces of the calcium carbonate whiskers, and interface transfer is inhibited; meanwhile, graded filling is formed by the POSS and the micron scale of the calcium carbonate whiskers, and meanwhile the rigidity and heat resistance of PP are improved; a triazole ring formed by click chemistry enables stress to be efficiently transmitted to the whisker and POSS network from a PP matrix; the nano dispersion of POSS fills the gaps among the whiskers, and reduces stress concentration. Meanwhile, triazole ring groups formed by azido and alkynyl are self-crosslinked under a high-temperature condition to form an olefin network or are subjected to cyclotrimerization to form an aromatic ring which has the characteristic of high-temperature char formation, a compact nano-structure protective layer is formed on the surface of the polypropylene material, and the polypropylene material has a good mass transfer and heat insulation barrier and good flame retardant property.

Description

Technical Field

[0001] The present invention relates to the technical field of powder materials, and particularly to a calcium-based powder material for polypropylene films and a preparation method thereof. Background Art

[0002] Polypropylene films are widely used in packaging, agriculture and other fields due to their excellent mechanical properties, transparency and processing properties; in order to reduce costs and improve properties (such as rigidity, gas permeability, thermal stability, etc.), calcium carbonate is widely studied as an inorganic filler.

[0003] Calcium carbonate is widely sourced, inexpensive, non-toxic and odorless, and is an environmentally friendly material. Calcium carbonate as a skeleton material can improve the mechanical properties, processing properties, heat resistance properties, etc. of polypropylene materials. However, there are still a large number of hydrophilic groups on the surface of calcium carbonate, and its compatibility with polypropylene materials is poor, and calcium carbonate is prone to sedimentation, thereby affecting the properties of polypropylene.

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

[0005] In order to achieve the above object, the present invention provides a calcium-based powder material for polypropylene films and a preparation method thereof. The calcium-based powder material prepared by this method has good dispersibility in polypropylene films, good processing fluidity, and good compatibility with polypropylene materials. It can significantly improve the mechanical properties of polypropylene films and at the same time improve their flame retardancy.

[0006] The high aspect ratio of calcium carbonate whiskers endows them with good mechanical properties in polypropylene materials. The calcium carbonate whiskers act as a rigid framework in the polypropylene materials, effectively inhibiting the deformation of polypropylene films. Meanwhile, when crack propagation encounters the whiskers, it deflects or branches, consuming more energy, and an anisotropic reinforcement network is formed during processing. The surface of the calcium carbonate whiskers is smooth and the aspect ratio is moderate, reducing the mechanical interlocking between particles, improving fluidity, and reducing the energy consumption during injection molding and extrusion. The calcium carbonate whiskers can reduce the shrinkage rate and thermal expansion coefficient of polypropylene, and reduce the warping of products.

[0007] A preparation method of a calcium-based powder material for polypropylene films comprises the following steps:

[0008] S1. Treat calcium carbonate whiskers with a coupling agent to obtain pretreated calcium carbonate whiskers;

[0009] S2. Using glycidyl methacrylate, acryloyl chloride, styrene, and pretreated calcium carbonate whiskers as raw materials, and azobisisobutyronitrile as an initiator, prepare azide-modified calcium carbonate whiskers;

[0010] S3. Using 4-ethynylphenylacetic acid and octa(4-aminophenyl)-POSS as raw materials, prepare alkynyl-containing POSS;

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

[0012] However, as an inorganic filler, the surface of calcium carbonate whiskers contains a large number of hydrophilic groups, with poor compatibility with polypropylene materials, poor dispersibility, and easy agglomeration, which in turn affect their mechanical properties and even easily generate cracks.

[0013] On the above basis, 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane are used to treat calcium carbonate whiskers simultaneously. In addition to improving the surface properties of calcium carbonate whiskers, new active groups are introduced. On the one hand, the surface energy of calcium carbonate whiskers is reduced, and on the other hand, its dispersibility in polypropylene materials is improved, thereby improving its mechanical properties, stability and other characteristics. Using glycidyl methacrylate, acryloyl chloride, and styrene as raw materials, and introducing calcium carbonate whiskers treated with a coupling agent, azide-modified calcium carbonate whiskers are prepared under the action of an initiator; the above-obtained azide-modified calcium carbonate whiskers also contain epoxy groups, benzene rings, ester groups, etc., which significantly improve the interfacial combination between calcium carbonate whiskers and polypropylene and reduce phase separation. At the same time, the styrene chain segments contained are non-polar and have high compatibility with polypropylene molecular chains. The interfacial binding force is enhanced through molecular chain entanglement. The ester groups introduced by acryloyl chloride produce dipole-dipole interactions with the tertiary carbon atoms in PP; the grafted polymer forms a spatial barrier on the surface of calcium carbonate whiskers, preventing the whiskers from approaching each other and improving the mechanical strength at the same time.

[0014] Using 4-ethynylphenylacetic acid and octaphenylaminopropyl-POSS as raw materials, alkynyl-POSS is prepared. Under the action of copper(I) bromide and pentamethyldiethylenetriamine, it undergoes a "click chemistry" reaction with azide-modified calcium carbonate whiskers to form a triazole ring, constructing a three-dimensional network structure on the surface of calcium carbonate whiskers to inhibit interfacial transfer; at the same time, POSS forms hierarchical filling with the micron scale of calcium carbonate whiskers, improving the rigidity and heat resistance of PP at the same time; the triazole ring formed by click chemistry enables stress to be efficiently transferred from the PP matrix to the whiskers and POSS network; the nanodispersion of POSS fills the voids between the whiskers, reducing stress concentration. Moreover, at the same time, the triazole ring groups formed by azide and alkynyl self-crosslink to form an olefin network or undergo a cyclotrimerization reaction to form an aromatic ring under high-temperature conditions, which has the characteristics of high-temperature char formation. A dense nanostructured protective layer is formed on the surface of the polypropylene material, which has a good mass transfer and heat insulation barrier and good flame retardant properties.

[0015] Further preferably, a preparation method of a calcium-based powder material for polypropylene films includes the following steps:

[0016] S1. Add calcium carbonate whiskers and a coupling agent to a 50-70 wt% ethanol aqueous solution, mix evenly, heat to 60-70 °C and treat for 1-5 h. After the reaction ends, 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, treat at 60 - 70 °C for 1 - 6 h. After the reaction ends, 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(4-aminophenyl)-POSS to 100 - 200 parts by weight of dimethyl sulfoxide and mix evenly. Then add 1 - 3 parts by weight of 1-hydroxybenzotriazole and 5 - 8 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and stir at room temperature for 24 - 48 h under a nitrogen atmosphere. After the reaction ends, concentrate, precipitate, wash, and dry to obtain alkyne-functionalized 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 alkyne-functionalized 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, and react at 40 - 60 °C for 24 h under a nitrogen atmosphere. After the reaction ends, wash and dry to obtain a calcium-based powder material for polypropylene film.

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

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

[0022] Advantages of the present invention:

[0023] 1. Compared with the prior art, alkyne-functionalized POSS is prepared using 4-ethynylphenylacetic acid and octa(4-aminophenyl)-POSS as raw materials, and undergoes a "click chemistry" reaction with azide-modified calcium carbonate whiskers under the action of cuprous bromide and pentamethyldiethylenetriamine to form a triazole ring, constructing a three-dimensional network structure on the surface of calcium carbonate whiskers to inhibit interfacial transfer; at the same time, the micron-scale of POSS and calcium carbonate whiskers forms hierarchical filling, simultaneously improving the rigidity and heat resistance of PP; the triazole ring formed by click chemistry enables efficient stress transfer from the PP matrix to the whiskers and POSS network; the nanodispersion of POSS fills the voids between whiskers, reducing stress concentration.

[0024] 2. Compared with the existing technology, the triazole ring groups formed by azide and alkyne groups self-crosslink under high temperature conditions to form an olefin network or cyclotrimerization reaction to form aromatic rings have the characteristics of high-temperature carbonization, forming a dense nanostructured protective layer on the surface of polypropylene materials, having a good mass transfer and heat insulation barrier, and having good flame retardant properties. DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in the present 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0026] Introduction of some raw materials used in the embodiments of the present invention:

[0027] The preparation method of the calcium carbonate whisker used in the embodiment is as follows: 20 mL of water and 80 mL of triethanolamine are mixed evenly and ultrasonically treated for 30 minutes, then 2.78 g of anhydrous calcium chloride and 10.5 g of urea are added and mixed evenly to obtain a mixed solution, and the mixed solution is transferred to a polytetrafluoroethylene-lined reactor at 120° C. for 6 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain calcium carbonate whiskers.

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

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

[0030] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

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

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

[0034] S2. Add 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 and mix evenly. Treat at 70 °C for 5 h. After the reaction ends, 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 octaphenylaminophenyl-POSS into 200 parts by weight of dimethyl sulfoxide and mix evenly. Then add 3 parts by weight of 1-hydroxybenzotriazole and 8 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride. Under a nitrogen atmosphere, stir at room temperature for 45 h. After the reaction ends, concentrate, precipitate, wash, and dry to obtain alkynyl-containing POSS.

[0036] S4. Add 3 parts by weight of the above-prepared azide-modified calcium carbonate whiskers and 0.5 parts by weight of alkynyl-containing POSS into 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. Under a nitrogen atmosphere, react at 60 °C for 24 h. After the reaction ends, wash and dry to obtain a calcium-based powder material for polypropylene film.

[0037] Example 2

[0038] A preparation method of a calcium-based powder material for polypropylene film, comprising the following steps: Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent into an aqueous ethanol solution of 70 wt% and mix evenly. Heat to 70 °C and treat for 3 h. After the reaction ends, centrifuge, wash, and dry to obtain a calcium-based powder material for polypropylene film; 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 preparation method of a calcium-based powder material for polypropylene film, comprising the following steps:

[0041] S1. Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent into 70wt% ethanol aqueous solution, mix evenly, heat to 70°C and treat for 3h. After the reaction ends, 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 5h. After the reaction ends, centrifuge, wash, and dry to obtain calcium-based powder material for polypropylene film.

[0043] Example 4

[0044] A preparation method of calcium-based powder material for polypropylene film, comprising the following steps:

[0045] S1. Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent into 70wt% ethanol aqueous solution, mix evenly, heat to 70°C and treat for 3h. After the reaction ends, 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 5h. After the reaction ends, centrifuge, wash, and dry to obtain azide-modified calcium carbonate whiskers.

[0047] S3. Mix 3 parts by weight of the above-prepared azide-modified calcium carbonate whiskers and 0.5 parts by weight of octaphenylamino-POSS into 50 parts by weight of N,N-dimethylformamide evenly, add 0.4 parts by weight of cuprous bromide and 0.45 parts by weight of pentamethyldiethylenetriamine, react at 60°C for 24h under a nitrogen atmosphere. After the reaction ends, wash and dry to obtain calcium-based powder material for polypropylene film.

[0048] Example 5

[0049] A preparation method of calcium-based powder material for polypropylene film, comprising the following steps:

[0050] S1. Add 3 parts by weight of calcium carbonate whiskers and 0.8 parts by weight of coupling agent into 70wt% ethanol aqueous solution, mix evenly, heat to 70°C and treat for 3h. After the reaction is completed, centrifuge, wash and dry to obtain pretreated calcium carbonate whiskers; wherein the coupling agent is composed of 3-(azidopropyl)triethoxysilane and 3-(methacryloxy)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 octaphenylaminophenyl-POSS into 200 parts by weight of dimethyl sulfoxide, mix evenly, then add 3 parts by weight of 1-hydroxybenzotriazole and 8 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and stir at room temperature for 45h under a nitrogen atmosphere. After the reaction is completed, concentrate, precipitate, wash and dry to obtain alkynyl-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 into 50 parts by weight of N,N-dimethylformamide, mix evenly, add 0.4 parts by weight of cuprous bromide and 0.45 parts by weight of pentamethyldiethylenetriamine, and react at 60°C for 24h 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 preparation method of calcium-based powder material for polypropylene film, comprising the following steps: Add 3 parts by weight of calcium carbonate whiskers and 0.5 parts by weight of octaphenylaminophenyl-POSS into 50 parts by weight of N,N-dimethylformamide, mix evenly, add 0.4 parts by weight of cuprous bromide and 0.45 parts by weight of pentamethyldiethylenetriamine, and react at 60°C for 24h under a nitrogen atmosphere. After the reaction is completed, wash and dry to obtain calcium-based powder material for polypropylene film.

[0055] Application Example 1

[0056] A method for preparing a polypropylene film is to uniformly mix 80 parts by weight of polypropylene (product number: R027063, Shanghai Aladdin Biochemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride grafted polypropylene (grade 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearic acid amide, and 15 parts by weight of the calcium-based powder material prepared from the polypropylene film of Example 1. Then, it is put into an extruder through a feeding device and heated to melt into a viscous liquid state. After filtration, it is extruded through a die head, and the melt temperature is controlled at 225 °C. The extruded melt is cooled by 20 °C cooling water to form a cast film. The cast film is first longitudinally stretched, with a preheating temperature of 130 °C, a stretching temperature of 100 °C, a stretching ratio of 5.5 times, and a setting temperature of 90 °C. Then, it is transversely stretched, with a preheating temperature of 165 °C, a stretching temperature of 155 °C, a stretching ratio of 6.2 times, and a setting temperature of 110 °C. Finally, it enters a traction machine, the temperature of the traction roller is 30 °C, and it is wound up to obtain the polypropylene film.

[0057] Application Example 2

[0058] A method for preparing a polypropylene film is to uniformly mix 80 parts by weight of polypropylene (product number: R027063, Shanghai Aladdin Biochemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride grafted polypropylene (grade 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearic acid amide, and 15 parts by weight of the calcium-based powder material prepared from the polypropylene film of Example 2. Then, it is put into an extruder through a feeding device and heated to melt into a viscous liquid state. After filtration, it is extruded through a die head, and the melt temperature is controlled at 225 °C. The extruded melt is cooled by 20 °C cooling water to form a cast film. The cast film is first longitudinally stretched, with a preheating temperature of 130 °C, a stretching temperature of 100 °C, a stretching ratio of 5.5 times, and a setting temperature of 90 °C. Then, it is transversely stretched, with a preheating temperature of 165 °C, a stretching temperature of 155 °C, a stretching ratio of 6.2 times, and a setting temperature of 110 °C. Finally, it enters a traction machine, the temperature of the traction roller is 30 °C, and it is wound up to obtain the polypropylene film.

[0059] Application Example 3

[0060] A method for preparing a polypropylene film comprises mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yien Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride grafted polypropylene (brand number 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearic acid amide, and 15 parts by weight of calcium-based powder material for polypropylene film prepared in Example 3, and feeding the mixture into an extruder through a feeding device, heating and melting the mixture into a viscous liquid state, and then filtering the mixture and mixing the mixture in a mold. The melt is extruded from a polypropylene head with the melt temperature controlled at 225°C; the extruded melt is cooled by cooling water at 20°C to form a cast sheet; the cast sheet is first longitudinally stretched with a preheating temperature of 130°C, a stretching temperature of 100°C, a stretching ratio of 5.5 times, and a setting temperature of 90°C; then transversely stretched with a preheating temperature of 165°C, a stretching temperature of 155°C, a stretching ratio of 6.2 times, and a setting temperature of 110°C; finally, it enters a traction machine with a traction roller temperature of 30°C and is rolled up to obtain a polypropylene film.

[0061] Application Example 4

[0062] A method for preparing a polypropylene film comprises mixing 80 parts by weight of polypropylene (product number: R027063, Shanghai Yien Chemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride grafted polypropylene (brand number 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearic acid amide, and 15 parts by weight of the polypropylene film calcium-based powder material prepared in Example 4, and feeding the mixture into an extruder through a feeding device, heating and melting the mixture into a viscous liquid state, and then filtering the mixture and then heating the mixture in a mold. The melt is extruded from a polypropylene head with the melt temperature controlled at 225°C; the extruded melt is cooled by cooling water at 20°C to form a cast sheet; the cast sheet is first longitudinally stretched with a preheating temperature of 130°C, a stretching temperature of 100°C, a stretching ratio of 5.5 times, and a setting temperature of 90°C; then transversely stretched with a preheating temperature of 165°C, a stretching temperature of 155°C, a stretching ratio of 6.2 times, and a setting temperature of 110°C; finally, it enters a traction machine with a traction roller temperature of 30°C and is rolled up to obtain a polypropylene film.

[0063] Application Example 5

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

[0065] Application Example 6

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

[0067] Application Example 7

[0068] A method for preparing a polypropylene film is to uniformly mix 80 parts by weight of polypropylene (product number: R027063, Shanghai Aladdin Biochemical Technology Co., Ltd.), 10 parts by weight of maleic anhydride grafted polypropylene (grade 50E806, DuPont), 5 parts by weight of antioxidant 1010, 3 parts by weight of stearic acid amide, and 15 parts by weight of calcium carbonate whiskers, and then put them into an extruder through a feeding device to be heated and melted into a viscous liquid state. After filtration, it is extruded in a die head, and the melt temperature is controlled at 225 °C; the extruded melt is cooled by 20 °C cooling water to form a cast sheet; the cast sheet is first longitudinally stretched, the preheating temperature is 130 °C, the stretching temperature is 100 °C, the stretching ratio is 5.5 times, and the setting temperature is 90 °C; then it is transversely stretched, the preheating temperature is 165 °C, the stretching temperature is 155 °C, the stretching ratio is 6.2 times, and the setting temperature is 110 °C; finally, it enters a traction machine, the temperature of the traction roller is 30 °C, and it is wound up to obtain a polypropylene film.

[0069] Test Example 1

[0070] Refer to GB / T 10003-2008 "Test Method for Tensile Properties of Plastic Films" to measure the longitudinal tensile strength and transverse tensile strength of the polypropylene film prepared in the application example.

[0071] Table 1 Test Results of Mechanical Properties

[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 can be seen from Table 1, by comparing Application Example 7 with Application Example 2, it can be found that the polypropylene film prepared by treating calcium carbonate whiskers with 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane in Application Example 2 has good mechanical properties. 3-(Azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane introduce new active groups while improving the surface characteristics of calcium carbonate whiskers. On the one hand, they reduce the surface energy of calcium carbonate whiskers, and on the other hand, they improve their dispersibility in the polypropylene material, thereby improving its mechanical properties, stability and other characteristics.

[0074] Comparing Application Example 1 with Application Examples 2 - 7, it is found that in Application Example 1, 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane are used to treat calcium carbonate whiskers simultaneously. Besides improving the surface properties of calcium carbonate whiskers, new active groups are introduced. On the one hand, the surface energy of calcium carbonate whiskers is reduced, and on the other hand, their dispersibility in polypropylene materials is improved, thereby improving their mechanical properties, stability and other characteristics. Using glycidyl methacrylate, acryloyl chloride, and styrene as raw materials, and introducing calcium carbonate whiskers treated with a coupling agent, azide-modified calcium carbonate whiskers are prepared under the action of an initiator; the above-mentioned obtained azide-modified calcium carbonate whiskers also contain epoxy groups, benzene rings, ester groups, etc., significantly improving the interfacial bonding between calcium carbonate whiskers and polypropylene, reducing phase separation. At the same time, the styrene segments contained are non-polar and have high compatibility with polypropylene molecular chains, enhancing the interfacial bonding force through molecular chain entanglement. The ester groups introduced by acryloyl chloride produce dipole-dipole interactions with the tertiary carbon atoms in PP; the grafted polymer forms a spatial barrier on the surface of calcium carbonate whiskers, preventing the whiskers from approaching each other and improving the mechanical strength at the same time. Using 4-ethynylphenylacetic acid and octaphenylamino-POSS as raw materials to prepare alkynyl-containing POSS, and under the action of cuprous bromide and pentamethyldiethylenetriamine, a "click chemistry" reaction occurs with azide-modified calcium carbonate whiskers to form a triazole ring, constructing a three-dimensional network structure on the surface of calcium carbonate whiskers to inhibit interfacial transfer; at the same time, POSS forms hierarchical filling with the micron scale of calcium carbonate whiskers, improving the rigidity and heat resistance of PP simultaneously; the triazole ring formed by click chemistry enables stress to be efficiently transferred from the PP matrix to the whiskers and POSS network; the nanodispersion of POSS fills the voids between the whiskers, reducing stress concentration.

[0075] Test Example 2

[0076] Refer to GB / T9639.1 - 2008 "Test Method for Impact Resistance of Plastic Films and Sheets" to conduct impact damage quality testing on the polypropylene films prepared in the application examples.

[0077] Table 2 Impact Damage Quality Test Results

[0078] Impact breakage mass at 25°C / 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 can be seen from Table 2, the polypropylene film prepared in Application Example 1 has good toughness. The possible reason is that alkynyl POSS is prepared from 4-ethynylphenylacetic acid and octaphenylaminopropyl-POSS, and undergoes a "click chemistry" reaction with azide-modified calcium carbonate whiskers under the action of cuprous bromide and pentamethyldiethylenetriamine to form a triazole ring, constructing a three-dimensional network structure on the surface of the calcium carbonate whiskers to inhibit interfacial transfer. At the same time, the micron scale of POSS and calcium carbonate whiskers forms a hierarchical filling, improving the rigidity and heat resistance of PP simultaneously. The triazole ring formed by click chemistry enables stress to be efficiently transferred from the PP matrix to the whiskers and POSS network. The nanodispersion of POSS fills the voids between the whiskers, reducing stress concentration.

[0080] Test Example 3

[0081] The vertical combustion performance was tested by referring to the vertical combustion test in GB / T 2408-2008 Plastics - Determination of burning behaviour - 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] The present invention utilizes the characteristics that the triazole ring group formed by azide and alkynyl self-crosslinks to form an olefin network or undergoes a cyclotrimerization reaction to form an aromatic ring at high temperatures, forming a dense nanostructured protective layer on the surface of the polypropylene material, having a good mass transfer and heat insulation barrier, and having good flame retardant performance.

[0085] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention through logical analysis, reasoning, or limited experiments based on the concept of the present invention on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A preparation method of a calcium-based powder material for polypropylene film, characterized in that: The azide-modified calcium-based material and alkynyl-POSS undergo a click chemical reaction under the action of cuprous bromide and pentamethyldiethylenetriamine to prepare a calcium-based powder material for polypropylene films.

2. The preparation method of the calcium-based powder material for polypropylene film according to claim 1, characterized in that: The preparation method of the azide-modified calcium-based material uses glycidyl methacrylate, acryloyl chloride, styrene, and a pretreated calcium-based material as raw materials, and under the action of an initiator, an azide-modified calcium carbonate whisker is prepared.

3. The preparation method of the calcium-based powder material for polypropylene film according to claim 1, characterized in that: The preparation method of the alkynyl-POSS uses 4-ethynylphenylacetic acid and octa(4-aminophenyl)-POSS as raw materials to prepare alkynyl-POSS.

4. The preparation method of the calcium-based powder material for polypropylene film according to claim 2, characterized in that: The preparation method of the pretreated calcium-based material is to treat the calcium-based material with a coupling agent to obtain the pretreated calcium-based material.

5. The preparation method of the calcium-based powder material for polypropylene film according to claim 4, characterized in that: The coupling agent is at least one of 3-(azidopropyl)triethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane.

6. The preparation method of the calcium-based powder material for polypropylene film according to claim 2, wherein: The initiator is azobisisobutyronitrile.

7. The preparation method of the calcium-based powder material for polypropylene film according to claim 4, characterized in that: The calcium-based material is calcium carbonate whisker.

8. The preparation method of the calcium-based powder material for polypropylene film according to claim 7, characterized in that: The preparation method of the calcium carbonate whisker is to mix water and triethanolamine evenly and perform ultrasonic treatment, then add anhydrous calcium chloride and urea and mix evenly to obtain a mixed solution. Transfer the above mixed solution to a reaction kettle with a polytetrafluoroethylene inner liner for reaction. After the reaction is completed, centrifuge, wash, and dry to obtain calcium carbonate whisker.

9. Calcium-based powder material for polypropylene film, characterized in that: It is prepared by using the preparation method described in any one of claims 1-8.