CPP (Chlorinated Polypropylene) membrane material for puncture-resistant packaging and preparation method of CPP membrane material

Abstract

The invention relates to a CPP membrane material for puncture-resistant packaging and a preparation method of the CPP membrane material, and belongs to the technical field of CPP membrane materials. The preparation method comprises the following steps: firstly, melting vinyl silane and grafting polypropylene to prepare modified polypropylene, then respectively modifying aluminum borate whisker and nano mesoporous silicon dioxide by using double-bond-containing silane, and mixing the aluminum borate whisker and the nano mesoporous silicon dioxide with a compatilizer to prepare two modified master batches; and mixing the modified master batch with modified polypropylene and an initiator, and carrying out melt extrusion and film casting to obtain the puncture-resistant CPP film material. The aluminum borate whisker can hinder crack propagation, the nano mesoporous silica can initiate micro deformation of a matrix to dissipate energy, and the aluminum borate whisker and the nano mesoporous silica cooperate with a cross-linked network to improve the puncture resistance of the membrane material; meanwhile, the three-dimensional cross-linked network and the rigid filler cooperate to limit high-temperature slippage of a polypropylene molecular chain, so that the membrane material is endowed with excellent high-temperature resistance. The high-temperature-resistant puncture-resistant cable material prepared by the invention has the effects of excellent puncture resistance and high temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of CPP film synthesis technology, specifically to a puncture-resistant CPP film for packaging and its preparation method. Background Technology

[0002] CPP film is widely used in packaging applications in the food, chemical, and pharmaceutical industries due to its excellent heat-sealing properties and mechanical strength, as well as its low cost. However, conventional CPP film, based on the characteristics of the polypropylene matrix, suffers from technical shortcomings such as insufficient puncture resistance and poor dimensional stability at high temperatures. When packaging sharp objects or heavy materials, the film is easily punctured and damaged, leading to leakage of the contents. In scenarios such as high-temperature sterilization, warehousing, and transportation, the polypropylene molecular chains are prone to slippage, causing the film to deform and its mechanical strength to drop sharply, failing to meet the requirements of high-end packaging.

[0003] Existing modification methods mostly optimize puncture resistance or high temperature resistance individually, making it difficult to achieve a synergistic improvement in both. Furthermore, some processes are complex and costly, limiting their application in the high-end packaging field. Therefore, developing a CPP film material that combines puncture resistance and high temperature resistance with a simple process is of great practical significance. Summary of the Invention

[0004] The purpose of this invention is to provide a puncture-resistant CPP film material for packaging and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a puncture-resistant CPP film material for packaging, comprising the following steps: (1) Mix polypropylene, vinyl silane and initiator in a mass ratio of 10:0.3~0.5:0.02, add to a twin-screw extruder, melt and mix the material for 6~10 min, cool to room temperature, granulate, and vacuum dry at 80℃ for 6 h to obtain modified polypropylene; (2) Add aluminum borate whiskers and silane coupling agent to silane treatment solution at a mass ratio of 10~15:1, reflux and stir at 60~70℃ for 5~7h, filter and wash, and vacuum dry at 100℃ for 12h to obtain modified aluminum borate whiskers; add nano-mesoporous silica and methacryloxypropyltrimethoxysilane to silane treatment solution at a mass ratio of 12~15:1, stir and react at 60~70℃ for 5~7h, filter and wash, and vacuum dry at 100℃ for 12h to obtain modified nano-mesoporous silica; mix the above two modified materials with compatibilizer at a mass ratio of 3~5:6~7, add them to twin-screw extruder, keep the material residence time for 6~8min, cool to room temperature, granulate and vacuum dry at 80℃ for 6h to obtain masterbatch A containing modified aluminum borate whiskers and masterbatch B containing modified nano-mesoporous silica; (3) Mix 70-80 parts by weight of modified polypropylene, 10-20 parts by weight of masterbatch A containing modified aluminum borate whiskers, 5-10 parts by weight of masterbatch B containing modified nano-mesoporous silica, 1-2 parts by weight of antioxidant and 0.5 parts by weight of initiator, add to a cast film extruder, stretch and shape the film material by traction roller, and then anneal at 100°C for 2 hours to obtain puncture-resistant packaging CPP film material.

[0006] Furthermore, the polypropylene mentioned in step (1) is a homopolymer polypropylene with a melt flow rate of 8 g / 10 min.

[0007] Furthermore, the initiator in step (1) is dicumyl peroxide.

[0008] Furthermore, the modified polypropylene particle size in step (1) is 3~5 mm.

[0009] Furthermore, the aluminum borate whiskers in step (2) have a diameter of 0.5~1μm and an aspect ratio of 20~30:1.

[0010] Furthermore, the silane coupling agent in step (2) is: methacryloyloxypropyltrimethoxysilane.

[0011] Furthermore, the nanoporous silica mentioned in step (2) has a pore size of 2 nm and a particle size of 30~50 nm.

[0012] Furthermore, the compatibilizer in step (2) is maleic anhydride-grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5 g / 10 min.

[0013] Furthermore, the antioxidant mentioned in step (3) is antioxidant 1010.

[0014] Furthermore, the thickness of the membrane material in step (3) is 40~50μm. Compared with the prior art, the beneficial effects achieved by the present invention are: This invention modifies polypropylene by mixing two modified reinforcing phases to achieve excellent puncture resistance and high temperature resistance.

[0015] This invention first obtains modified polypropylene by melt grafting vinyl silane onto polypropylene; then, aluminum borate whiskers and nanoporous silica are modified separately with double-bonded silane, and then mixed with compatibilizers to obtain two modified masterbatches. These masterbatches are then mixed with modified polypropylene and an initiator, and melt extrusion and casting are used to obtain puncture-resistant CPP film for packaging. When the film is subjected to puncture impact, the aluminum borate whiskers first hinder crack propagation. At the same time, the uniformly dispersed nanoporous silica particles can induce a large number of tiny deformations in the surrounding polypropylene matrix, dissipating a large amount of energy. The two work together through a cross-linking network to give the film excellent puncture resistance. Furthermore, the three-dimensional cross-linking network and rigid filler work together to limit the high-temperature slippage of polypropylene molecular chains, giving the material excellent high-temperature resistance. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The test methods for various indicators of the puncture-resistant CPP film material for packaging produced in the following embodiments are as follows: Puncture resistance test: According to the standard provided by GB / T36363-2018, the CPP film materials prepared in Examples 1-5 and Comparative Examples 1-7 were placed in an oven at 200℃ for 30 minutes, and then removed for puncture strength test at a test rate of (100±10) mm / min.

[0018] High temperature resistance test: Place the high temperature resistant film in an oven at 180℃ for 10 seconds and observe the time it takes for it to deform. If it is less than 3 seconds, it is unqualified. If it does not deform within 10 seconds, it is recorded as >10 seconds.

[0019] Example 1 (1) Homopolymer polypropylene, vinyl silane and dicumyl peroxide with a melt flow rate of 8 g / 10 min were mixed in a mass ratio of 10:0.3:0.02 and added to a twin-screw extruder. The parameters were set as follows: feeding section 160℃, plasticizing section 180℃, reaction section 190℃, homogenizing section 200℃, die head 200℃, material melting and mixing time 6 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into granules with a particle size of 3 mm by a pelletizer. The pellets were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to remove residual ungrafted vinyl silane and volatile matter, thus obtaining modified polypropylene. (2) Methacryloxypropyltrimethoxysilane was mixed with ethanol and water at a mass ratio of 5:85:10, and the pH was adjusted to 4 with 0.5M acetic acid aqueous solution. The mixture was stirred at 300 rpm for 30 min at room temperature to obtain a silane treatment solution. Aluminum borate whiskers with a diameter of 0.5 μm and an aspect ratio of 20:1 were added to the silane treatment solution at a mass ratio of 10:1 with methacryloxypropyltrimethoxysilane. The mixture was refluxed at 500 rpm for 5 h at 60 °C. After filtration and washing three times with anhydrous ethanol, the mixture was dried at 100 °C and vacuum degree -0.09 MPa for 12 h to obtain modified aluminum borate whiskers. (3) Mesoporous silica with a pore size of 2 nm and a particle size of 30 nm was added to a silane treatment solution at a mass ratio of 12:1. The mixture was stirred under reflux at 500 rpm for 5 h at 60 °C. After filtration and washing three times with anhydrous ethanol, the modified nanoporous silica was dried at 100 °C and vacuum degree -0.09 MPa for 12 h. (4) Modified aluminum borate whiskers and modified nanoporous silica were mixed with maleic anhydride-grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5 g / 10 min at a mass ratio of 3:6. The mixtures were added to a twin-screw extruder and the parameters were set as follows: feeding section 150℃, plasticizing section 160℃, reaction section 170℃, homogenizing section 180℃, die head 180℃, screw speed 160 rpm, material residence time 6 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into granules with a particle size of 3 mm by a pelletizer. The pellets were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to obtain masterbatch A containing modified aluminum borate whiskers and masterbatch B containing modified nanoporous silica. (5) 70 parts by weight of modified polypropylene, 20 parts by weight of masterbatch A containing modified aluminum borate whiskers, 5 parts by weight of masterbatch B containing modified nano-mesoporous silica, 1 part by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide are mixed and added to a cast film extruder. The parameters are set as follows: the extruder temperature from the feed port to the die head is 180℃, 185℃, 190℃, 200℃ and 200℃ respectively. The melt is cast through the T-die to the surface of the 25℃ cooling roller. The traction speed is 3.5m / min. The film is stretched and shaped by the traction roller. The film thickness is 40μm. Then it is annealed at 100℃ for 2h to eliminate the internal stress of the film and promote the formation of cross-linked network. After annealing, it is naturally cooled to room temperature to obtain puncture-resistant CPP film for packaging.

[0020] Example 2 (1) Homopolymer polypropylene, vinyl silane and dicumyl peroxide with a melt flow rate of 8 g / 10 min were mixed at a mass ratio of 10:0.35:0.02 and added to a twin-screw extruder. The parameters were set as follows: feeding section 160℃, plasticizing section 180℃, reaction section 190℃, homogenizing section 200℃, die head 200℃, material melting and mixing time 7 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into granules with a particle size of 3.5 mm by a pelletizer. The pellets were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to remove residual ungrafted vinyl silane and volatile matter, and modified polypropylene was obtained. (2) Methacryloxypropyltrimethoxysilane was mixed with ethanol and water at a mass ratio of 5:85:10, and the pH was adjusted to 4.2 with 0.5M acetic acid aqueous solution. The mixture was stirred at 300 rpm for 30 min at room temperature to obtain a silane treatment solution. Aluminum borate whiskers with a diameter of 0.6 μm and an aspect ratio of 22:1 were added to the silane treatment solution at a mass ratio of 11:1 with methacryloxypropyltrimethoxysilane. The mixture was refluxed at 500 rpm for 5.5 h at 62 °C. After filtration and washing three times with anhydrous ethanol, the mixture was dried at 100 °C and vacuum degree -0.09 MPa for 12 h to obtain modified aluminum borate whiskers. (3) Mesoporous silica with a pore size of 2 nm and a particle size of 35 nm was added to a silane treatment solution at a mass ratio of 13:1. The mixture was stirred under reflux at 500 rpm for 5.5 h at 62 °C. After filtration and washing three times with anhydrous ethanol, the mixture was dried at 100 °C and vacuum degree -0.09 MPa for 12 h to obtain modified mesoporous silica. (4) Modified aluminum borate whiskers and modified nanoporous silica were mixed with maleic anhydride-grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5 g / 10 min at a mass ratio of 3.5:6.2. The mixtures were added to a twin-screw extruder and the parameters were set as follows: feeding section 150℃, plasticizing section 160℃, reaction section 170℃, homogenizing section 180℃, die head 180℃, screw speed 160 rpm, material residence time 6.5 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into granules with a particle size of 3.5 mm by a pelletizer. The pellets were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to obtain masterbatch A containing modified aluminum borate whiskers and masterbatch B containing modified nanoporous silica. (5) 72 parts by weight of modified polypropylene, 18 parts by weight of masterbatch A containing modified aluminum borate whiskers, 6 parts by weight of masterbatch B containing modified nano-mesoporous silica, 1.2 parts by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide are mixed and added to a cast film extruder. The parameters are set as follows: the extruder temperature from the feed port to the die head is 180℃, 185℃, 190℃, 200℃ and 200℃ respectively. The melt is cast through the T-die to the surface of the 25℃ cooling roller. The traction speed is 3.5m / min. The film is stretched and shaped by the traction roller. The film thickness is 42μm. Then it is annealed at 100℃ for 2h to eliminate the internal stress of the film and promote the formation of cross-linked network. After annealing, it is naturally cooled to room temperature to obtain puncture-resistant CPP film for packaging.

[0021] Example 3 (1) Homopolymer polypropylene, vinyl silane and dicumyl peroxide with a melt flow rate of 8 g / 10 min were mixed at a mass ratio of 10:0.4:0.02 and added to a twin-screw extruder. The parameters were set as follows: feeding section 160℃, plasticizing section 180℃, reaction section 190℃, homogenizing section 200℃, die head 200℃, material melting and mixing time 8 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into 4 mm particles by a pelletizer. The particles were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to remove residual ungrafted vinyl silane and volatile matter, thus obtaining modified polypropylene. (2) Methacryloxypropyltrimethoxysilane was mixed with ethanol and water at a mass ratio of 5:85:10, and the pH was adjusted to 4.5 with 0.5M acetic acid aqueous solution. The mixture was stirred at 300 rpm for 30 min at room temperature to obtain silane treatment solution. Aluminum borate whiskers with a diameter of 0.7 μm and an aspect ratio of 25:1 were added to the silane treatment solution at a mass ratio of 13:1 with methacryloxypropyltrimethoxysilane. The mixture was refluxed at 500 rpm for 6 h at 65 °C. After filtration and washing three times with anhydrous ethanol, the mixture was dried at 100 °C and vacuum degree -0.09 MPa for 12 h to obtain modified aluminum borate whiskers. (3) Mesoporous silica with a pore size of 2 nm and a particle size of 40 nm was added to a silane treatment solution at a mass ratio of 13.5:1. The mixture was stirred under reflux at 500 rpm for 6 h at 65 °C. After filtration and washing three times with anhydrous ethanol, the mixture was dried at 100 °C and vacuum degree -0.09 MPa for 12 h to obtain modified mesoporous silica. (4) Modified aluminum borate whiskers and modified nanoporous silica were mixed with maleic anhydride grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5 g / 10 min at a mass ratio of 4:6.5. The mixtures were added to a twin-screw extruder and the parameters were set as follows: feeding section 150℃, plasticizing section 160℃, reaction section 170℃, homogenizing section 180℃, die head 180℃, screw speed 160 rpm, material residence time 7 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into 4 mm particles by a pelletizer. The particles were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to obtain masterbatch A containing modified aluminum borate whiskers and masterbatch B containing modified nanoporous silica. (5) 75 parts by weight of modified polypropylene, 15 parts by weight of masterbatch A containing modified aluminum borate whiskers, 8 parts by weight of masterbatch B containing modified nano-mesoporous silica, 1.5 parts by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide are mixed and added to a cast film extruder. The parameters are set as follows: the extruder temperature from the feed port to the die head is 180℃, 185℃, 190℃, 200℃ and 200℃ respectively. The melt is cast through the T-die to the surface of the 25℃ cooling roller. The traction speed is 3.5m / min. The film is stretched and shaped by the traction roller. The film thickness is 45μm. Then it is annealed at 100℃ for 2h to eliminate the internal stress of the film and promote the formation of cross-linked network. After annealing, it is naturally cooled to room temperature to obtain puncture-resistant CPP film for packaging.

[0022] Example 4 (1) Homopolymer polypropylene, vinyl silane and dicumyl peroxide with a melt flow rate of 8 g / 10 min were mixed at a mass ratio of 10:0.45:0.02 and added to a twin-screw extruder. The parameters were set as follows: feeding section 160℃, plasticizing section 180℃, reaction section 190℃, homogenizing section 200℃, die head 200℃, material melting and mixing time 9 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into 4.5 mm particles by a pelletizer. The particles were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to remove residual ungrafted vinyl silane and volatile matter, thus obtaining modified polypropylene. (2) Methacryloxypropyltrimethoxysilane was mixed with ethanol and water at a mass ratio of 5:85:10, and the pH was adjusted to 4.8 with 0.5M acetic acid aqueous solution. The mixture was stirred at 300 rpm for 30 min at room temperature to obtain a silane treatment solution. Aluminum borate whiskers with a diameter of 0.9 μm and an aspect ratio of 28:1 were added to the silane treatment solution at a mass ratio of 14:1 with methacryloxypropyltrimethoxysilane. The mixture was refluxed at 68 °C and stirred at 500 rpm for 6.5 h. After filtration and washing three times with anhydrous ethanol, the mixture was dried at 100 °C and vacuum degree -0.09 MPa for 12 h to obtain modified aluminum borate whiskers. (3) Mesoporous silica with a pore size of 2 nm and a particle size of 45 nm was added to a silane treatment solution at a mass ratio of 14:1. The mixture was stirred under reflux at 500 rpm for 6.5 h at 68 °C. After filtration and washing three times with anhydrous ethanol, the modified nanoporous silica was dried at 100 °C and vacuum degree -0.09 MPa for 12 h. (4) Modified aluminum borate whiskers and modified nanoporous silica were mixed with maleic anhydride-grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5 g / 10 min at a mass ratio of 4.5:6.8. The mixtures were added to a twin-screw extruder and the parameters were set as follows: feeding section 150℃, plasticizing section 160℃, reaction section 170℃, homogenizing section 180℃, die head 180℃, screw speed 160 rpm, material residence time 7.5 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into 4.5 mm particles by a pelletizer. The particles were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to obtain masterbatch A containing modified aluminum borate whiskers and masterbatch B containing modified nanoporous silica. (5) 78 parts by weight of modified polypropylene, 13 parts by weight of masterbatch A containing modified aluminum borate whiskers, 9 parts by weight of masterbatch B containing modified nano-mesoporous silica, 1.8 parts by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide are mixed and added to a cast film extruder. The parameters are set as follows: the extruder temperature from the feed port to the die head is 180℃, 185℃, 190℃, 200℃ and 200℃ respectively. The melt is cast through the T-die to the surface of the 25℃ cooling roller. The traction speed is 3.5m / min. The film is stretched and shaped by the traction roller. The film thickness is 48μm. Then it is annealed at 100℃ for 2h to eliminate the internal stress of the film and promote the formation of cross-linked network. After annealing, it is naturally cooled to room temperature to obtain puncture-resistant CPP film for packaging.

[0023] Example 5 (1) Homopolymer polypropylene, vinyl silane and dicumyl peroxide with a melt flow rate of 8 g / 10 min were mixed in a mass ratio of 10:0.5:0.02 and added to a twin-screw extruder. The parameters were set as follows: feeding section 160℃, plasticizing section 180℃, reaction section 190℃, homogenizing section 200℃, die head 200℃, material melting and mixing time 10 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into granules with a particle size of 5 mm by a pelletizer. The pellets were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to remove residual ungrafted vinyl silane and volatile matter, thus obtaining modified polypropylene. (2) Methacryloxypropyltrimethoxysilane was mixed with ethanol and water at a mass ratio of 5:85:10, and the pH was adjusted to 5 with 0.5M acetic acid aqueous solution. The mixture was stirred at 300 rpm for 30 min at room temperature to obtain a silane treatment solution. Aluminum borate whiskers with a diameter of 1 μm and an aspect ratio of 30:1 were added to the silane treatment solution at a mass ratio of 15:1 with methacryloxypropyltrimethoxysilane. The mixture was refluxed at 70 °C and stirred at 500 rpm for 7 h. After filtration and washing three times with anhydrous ethanol, the mixture was dried at 100 °C and vacuum degree -0.09 MPa for 12 h to obtain modified aluminum borate whiskers. (3) Mesoporous silica with a pore size of 2 nm and a particle size of 50 nm was added to a silane treatment solution at a mass ratio of 15:1. The mixture was stirred under reflux at 70 °C and 500 rpm for 7 h. After filtration and washing three times with anhydrous ethanol, the modified nanoporous silica was dried at 100 °C and vacuum degree -0.09 MPa for 12 h. (4) Modified aluminum borate whiskers and modified nanoporous silica were mixed with maleic anhydride grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5 g / 10 min at a mass ratio of 5:7. The mixtures were added to a twin-screw extruder and the parameters were set as follows: feeding section 150℃, plasticizing section 160℃, reaction section 170℃, homogenizing section 180℃, die head 180℃, screw speed 160 rpm, material residence time 8 min. The extruded strip was cooled to room temperature in a cooling water bath at 25℃ and cut into 5 mm particles by a pelletizer. The particles were dried at 80℃ and vacuum degree -0.09 MPa for 6 h to obtain masterbatch A containing modified aluminum borate whiskers and masterbatch B containing modified nanoporous silica. (5) Mix 80 parts by weight of modified polypropylene, 10 parts by weight of masterbatch A containing modified aluminum borate whiskers, 10 parts by weight of masterbatch B containing modified nano-mesoporous silica, 2 parts by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide, and add them to the cast film extruder. Set the parameters: the extruder temperature from the feed port to the die head is 180℃, 185℃, 190℃, 200℃ and 200℃ respectively. The melt is cast through the T-die to the surface of the 25℃ cooling roller. The traction speed is 3.5m / min. The film is stretched and shaped by the traction roller. The film thickness is 50μm. Then, it is annealed at 100℃ for 2h to eliminate the internal stress of the film and promote the formation of cross-linked network. After annealing, it is naturally cooled to room temperature to obtain puncture-resistant CPP film for packaging.

[0024] Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that step (1) is omitted, and step (5) is changed to: 75 parts by weight of homopolymer polypropylene with a melt flow rate of 8 g / 10 min, 15 parts by weight of masterbatch A containing modified aluminum borate whiskers, 8 parts by weight of masterbatch B containing modified nanoporous silica, 1.5 parts by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide are mixed and added to a cast film extruder. The parameters are set as follows: the extruder starts from the point of addition. The temperatures from the feed inlet to the die head are 180℃, 185℃, 190℃, 200℃, and 200℃ respectively. The melt is cast through the T-die head to the surface of the 25℃ cooling roller. The traction speed is 3.5m / min. The film material is stretched and shaped by the traction roller, and the film material thickness is 45μm. Then, it is annealed at 100℃ for 2 hours to eliminate internal stress and promote the formation of cross-linked network. After annealing, it is naturally cooled to room temperature to obtain puncture-resistant CPP film material for packaging. The remaining steps are the same as in Example 3.

[0025] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that step (2) is omitted, and step (4) is changed to: the modified nanoporous silica and maleic anhydride grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5g / 10min are mixed at a mass ratio of 4:6.5 and added to a twin-screw extruder. The parameters are set as follows: feeding section 150℃, plasticizing section 160℃, reaction section 170℃, homogenizing section 180℃, die head 180℃, screw speed 160rpm, material residence time 7min. The extruded strip is cooled to room temperature in a cooling water bath at 25℃ and cut into 4mm particles by a pelletizer. The particles are then dried at 80℃ and vacuum degree -0.09MPa for 6h to obtain masterbatch B containing modified nanoporous silica; step (5) is changed to: The following steps were modified: 75 parts by weight of modified polypropylene, 8 parts by weight of masterbatch B containing modified nanoporous silica, 1.5 parts by weight of antioxidant 1010, and 0.5 parts by weight of dicumyl peroxide were mixed and added to a cast film extruder. The parameters were set as follows: the extruder temperatures from the feed port to the die head were 180°C, 185°C, 190°C, 200°C, and 200°C, respectively. The melt was cast through a T-die to the surface of a 25°C cooling roller at a traction speed of 3.5 m / min. The film was stretched and shaped by the traction roller to a thickness of 45 μm. The film was then annealed at 100°C for 2 hours to eliminate internal stress and promote the formation of a cross-linked network. After annealing, the film was naturally cooled to room temperature to obtain a puncture-resistant CPP film for packaging. The remaining steps were the same as in Example 3.

[0026] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that step (3) is omitted, and step (4) is changed to: the modified aluminum borate whiskers and maleic anhydride grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5g / 10min are mixed at a mass ratio of 4:6.5 and added to a twin-screw extruder. The parameters are set as follows: feeding section 150℃, plasticizing section 160℃, reaction section 170℃, homogenizing section 180℃, die head 180℃, screw speed 160rpm, material residence time 7min. The extruded strip is cooled to room temperature in a cooling water bath at 25℃ and cut into 4mm particles by a pelletizer. The particles are then dried at 80℃ and vacuum degree -0.09MPa for 6h to obtain masterbatch B containing modified nanoporous silica. Step (5) is then changed to: The following steps were modified: 75 parts by weight of modified polypropylene, 15 parts by weight of masterbatch A containing modified aluminum borate whiskers, 1.5 parts by weight of antioxidant 1010, and 0.5 parts by weight of dicumyl peroxide were mixed and added to a cast film extruder. The parameters were set as follows: the extruder temperatures from the feed port to the die head were 180°C, 185°C, 190°C, 200°C, and 200°C, respectively. The melt was cast through a T-die to the surface of a 25°C cooling roller at a traction speed of 3.5 m / min. The film was stretched and shaped by the traction roller to a thickness of 45 μm. The film was then annealed at 100°C for 2 hours to eliminate internal stress and promote the formation of a cross-linked network. After annealing, the film was naturally cooled to room temperature to obtain a puncture-resistant CPP film for packaging. The remaining steps were the same as in Example 3.

[0027] Comparative Example 4 The difference between Comparative Example 4 and Example 3 is that step (4) is omitted, and step (5) is changed to: 75 parts by weight of modified polypropylene, 15 parts by weight of modified aluminum borate whiskers, 8 parts by weight of modified nano-mesoporous silica, 1.5 parts by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide are mixed and added to a cast film extruder. The parameters are set as follows: the extruder temperature from the feed port to the die head is 180°C, 185°C, 190°C, 200°C and 200°C respectively. The melt is cast through the T-die to the surface of the 25°C cooling roller. The traction speed is 3.5 m / min. The film material is stretched and shaped by the traction roller. The film material thickness is 45 μm. Then it is annealed at 100°C for 2 hours to eliminate the internal stress of the film and promote the formation of the cross-linking network. After annealing, it is naturally cooled to room temperature to obtain a puncture-resistant CPP film material for packaging. The remaining steps are the same as in Example 3.

[0028] Comparative Example 5 The difference between Comparative Example 5 and Example 3 is that steps (2), (3), and (4) are omitted, and step (5) is changed to: mixing 75 parts by weight of modified polypropylene, 15 parts by weight of aluminum borate whiskers with a diameter of 0.7 μm and an aspect ratio of 25:1, 8 parts by weight of modified nano-mesoporous silica with a mesoporous pore size of 2 nm and a particle size of 40 nm, 1.5 parts by weight of antioxidant 1010, and 0.5 parts by weight of dicumyl peroxide, and adding the mixture to a cast film extruder, setting the parameters. The extruder temperatures from the feed port to the die head are 180℃, 185℃, 190℃, 200℃, and 200℃ respectively. The melt is cast through the T-die to the surface of the 25℃ cooling roller. The traction speed is 3.5m / min. The film material is stretched and shaped by the traction roller, and the film thickness is 45μm. Then, it is annealed at 100℃ for 2 hours to eliminate internal stress and promote the formation of cross-linked network. After annealing, it is naturally cooled to room temperature to obtain puncture-resistant CPP film material for packaging. The remaining steps are the same as in Example 3.

[0029] Comparative Example 6 The difference between Comparative Example 6 and Example 3 is that steps (2), (3), and (4) are omitted, and step (5) is changed to: 75 parts by weight of modified polypropylene, 8 parts by weight of modified nano-mesoporous silica with a pore size of 2 nm and a particle size of 40 nm, 1.5 parts by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide are mixed and added to a cast film extruder. The parameters are set as follows: the extruder temperature from the feed port to the die head is 180°C, 185°C, 190°C, 200°C and 200°C respectively. The melt is cast through the T-die to the surface of the 25°C cooling roller. The traction speed is 3.5 m / min. The film material is stretched and shaped by the traction roller. The film material thickness is 45 μm. Then it is annealed at 100°C for 2 hours to eliminate the internal stress of the film and promote the formation of the cross-linking network. After annealing, it is naturally cooled to room temperature to obtain a puncture-resistant CPP film material for packaging. The remaining steps are the same as in Example 3.

[0030] Comparative Example 7 The difference between Comparative Example 7 and Example 3 is that steps (2), (3), and (4) are omitted, and step (5) is changed to: 75 parts by weight of modified polypropylene, 15 parts by weight of aluminum borate whiskers with a diameter of 0.7 μm and an aspect ratio of 25:1, 1.5 parts by weight of antioxidant 1010 and 0.5 parts by weight of dicumyl peroxide are mixed and added to a cast film extruder. The parameters are set as follows: the extruder temperature from the feed port to the die head is 180°C, 185°C, 190°C, 200°C and 200°C respectively. The melt is cast through the T-die to the surface of the 25°C cooling roller. The traction speed is 3.5 m / min. The film material is stretched and shaped by the traction roller. The film material thickness is 45 μm. Then it is annealed at 100°C for 2 hours to eliminate the internal stress of the film and promote the formation of the cross-linking network. After annealing, it is naturally cooled to room temperature to obtain a puncture-resistant CPP film material for packaging. The remaining steps are the same as in Example 3.

[0031] Example of effect Table 1 below shows the performance analysis results of the puncture-resistant CPP film materials used in Examples 1 to 5 and Comparative Examples 1 to 7 of the present invention.

[0032] Table 1

[0033] A comparison of the puncture strength experimental data of the examples and comparative examples reveals that the present invention first obtains modified polypropylene by melt grafting vinyl silane onto polypropylene; then, aluminum borate whiskers and nanoporous silica are modified separately with double-bonded silane, and then mixed with compatibilizers to obtain two modified masterbatches, which are then mixed with modified polypropylene and an initiator, and processed by melt extrusion and casting to obtain puncture-resistant CPP film material for packaging; when the film material is subjected to puncture impact, the aluminum borate whiskers first hinder crack propagation, while the uniformly dispersed nanoporous silica particles can induce a large number of tiny deformations in the surrounding polypropylene matrix, dissipating a large amount of energy. The two work together through the cross-linking network to give the film material excellent puncture resistance; a comparison of the high temperature resistance experimental data of the examples and comparative examples reveals that the three-dimensional cross-linking network and rigid filler work together in the present invention to limit the high-temperature slippage of polypropylene molecular chains, giving the material excellent high temperature resistance.

[0034] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A puncture-resistant CPP film material for packaging, characterized in that, Includes the following steps: (1) Mix polypropylene, vinyl silane and initiator in a mass ratio of 10:0.3~0.5:0.02, add to a twin-screw extruder, melt and mix the material for 6~10 min, cool to room temperature, granulate, and vacuum dry at 80℃ for 6 h to obtain modified polypropylene; (2) Add aluminum borate whiskers and silane coupling agent to silane treatment solution at a mass ratio of 10~15:1, reflux and stir at 60~70℃ for 5~7h, filter and wash, and vacuum dry at 100℃ for 12h to obtain modified aluminum borate whiskers; add nano-mesoporous silica and methacryloxypropyltrimethoxysilane to silane treatment solution at a mass ratio of 12~15:1, stir and react at 60~70℃ for 5~7h, filter and wash, and vacuum dry at 100℃ for 12h to obtain modified nano-mesoporous silica; mix the above two modified materials with compatibilizer at a mass ratio of 3~5:6~7, add them to twin-screw extruder, keep the material residence time for 6~8min, cool to room temperature, granulate and vacuum dry at 80℃ for 6h to obtain masterbatch A containing modified aluminum borate whiskers and masterbatch B containing modified nano-mesoporous silica; (3) Mix 70-80 parts by weight of modified polypropylene, 10-20 parts by weight of masterbatch A containing modified aluminum borate whiskers, 5-10 parts by weight of masterbatch B containing modified nano-mesoporous silica, 1-2 parts by weight of antioxidant and 0.5 parts by weight of initiator, add to a cast film extruder, stretch and shape the film material by traction roller, and then anneal at 100°C for 2 hours to obtain puncture-resistant packaging CPP film material.

2. The CPP film material for puncture-resistant packaging according to claim 1, characterized in that, The polypropylene mentioned in step (1) is a homopolymer polypropylene with a melt flow rate of 8 g / 10 min.

3. The CPP film material for puncture-resistant packaging according to claim 1, characterized in that, The initiator in step (1) is dicumyl peroxide.

4. The CPP film material for puncture-resistant packaging according to claim 1, characterized in that, The modified polypropylene particle size in step (1) is 3~5 mm.

5. The CPP film material for puncture-resistant packaging according to claim 1, characterized in that, The aluminum borate whiskers in step (2) have a diameter of 0.5~1μm and an aspect ratio of 20~30:

1.

6. The CPP film material for puncture-resistant packaging according to claim 1, characterized in that, The silane coupling agent in step (2) is: methacryloyloxypropyltrimethoxysilane.

7. The CPP film material for puncture-resistant packaging according to claim 1, characterized in that, The nanoporous silica mentioned in step (2) has a pore size of 2 nm and a particle size of 30~50 nm.

8. The CPP film material for puncture-resistant packaging according to claim 1, characterized in that, The compatibilizer in step (2) is maleic anhydride-grafted polypropylene with a grafting rate of 0.8% and a melt flow rate of 5 g / 10 min.

9. The CPP film material for puncture-resistant packaging according to claim 1, characterized in that, The antioxidant mentioned in step (3) is antioxidant 1010.

10. A puncture-resistant CPP film material for packaging according to claim 1, characterized in that, The thickness of the membrane material in step (3) is 40~50μm.

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