A method for preparing solvent-free composite polypropylene film

Abstract

The invention relates to the technical field of polypropylene film preparation, and in particular to a method for preparing a solvent-free composite polypropylene film, which is used to solve the problem that the existing polypropylene film has poor environmental protection performance and anti-fungal performance, which limits its application prospects. The preparation method adopts a hot pressing and melting composite method to form a solvent-free composite polypropylene film with a four-layer structure, so that the film has good mechanical properties, and can be directly composited with other materials only by heating without using any adhesive, and has strong composite fastness and convenient operation. In addition, no organic solvent is needed in the composite process, which significantly reduces the production cost and effectively reduces the pollution of the volatilization of organic solvents to the environment. At the same time, the modified polypropylene has excellent antibacterial performance, significantly improves the anti-fungal ability of the film, so that the film has a wide range of application prospects in multiple fields, and provides strong support for improving product quality and protecting user health.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene film preparation, and in particular to a method for preparing a solvent-free composite polypropylene film. Background Art

[0002] At present, biaxially oriented polypropylene film is increasingly being used in various fields of packaging due to its good physical and mechanical properties, chemical stability and processing performance. As people's requirements for food safety, medical health and environmental protection continue to increase, the performance requirements for packaging materials are becoming increasingly stringent.

[0003] However, due to the poor antibacterial properties of polypropylene materials themselves, traditional polypropylene films have certain deficiencies in anti-mildew performance. In humid environments or long-term storage conditions, they are easily corroded by mold, affecting the quality and service life of the product. In addition, organic solvents are used in the composite process, resulting in the production of a large amount of volatile organic compounds, which pollute the environment.

[0004] Therefore, it is of great significance to develop a method for preparing solvent-free composite polypropylene film. Summary of the invention

[0005] In order to overcome the above technical problems, the purpose of the present invention is to provide a method for preparing a solvent-free composite polypropylene film, which solves the problem that the existing polypropylene film has poor environmental performance and anti-fungal performance, which limits its application prospects.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a solvent-free composite polypropylene film comprises the following steps:

[0008] Step 1: Weigh 95-98% of modified polypropylene and 2-5% of anti-blocking agent according to the mass ratio, and mix the modified polypropylene and the anti-blocking agent evenly to obtain an anti-blocking raw material;

[0009] Step 2: Weigh 94-98% of modified polypropylene and 2-6% of antistatic masterbatch according to the mass ratio, and mix the modified polypropylene and antistatic masterbatch evenly to obtain a supporting raw material;

[0010] Step 3: adding the anti-adhesive raw material, the supporting raw material, the connecting raw material and the adhesive raw material to the No. 1 extruder, the No. 2 extruder, the No. 3 extruder and the No. 4 extruder respectively and melt-extruded, filtering through a 320-mesh filter and then converging to a die head of a four-layer structure, and extruding to form a four-layer composite thick sheet;

[0011] Step 4: The four-layer composite thick sheet is cooled to 30-35°C by cooling water, and then longitudinally stretched at a longitudinal stretching process temperature of 95-138°C, with a longitudinal stretching ratio of 4.7-5.1, and then transversely stretched at a transverse stretching process temperature of 150-170°C, with a transverse stretching ratio of 8-10 times to form a film. The film is cooled by air shower and then corona treated at a power of 18-35Wmin / m 2 The corona treatment is carried out under the conditions of , and the film mother roll is harvested. The film mother roll is subjected to aging treatment, slitting and packaging to obtain a solvent-free composite polypropylene film.

[0012] As a further solution of the present invention: the anti-adhesive agent in step 1 is one of silicon dioxide, glass beads, calcium carbonate, calcined silica, kaolin, and polymethyl methacrylate.

[0013] As a further solution of the present invention: the antistatic masterbatch in step 2 is one of Konstanp AT4030PP, Best AS2335PP and FAS25PP.

[0014] As a further solution of the present invention: the connecting raw material in step three is one of high-pressure polyethylene, ethylene-vinyl acetate, ethylene-acrylic acid copolymer and ethylene-ethyl acrylate copolymer.

[0015] As a further solution of the present invention: the adhesive raw material in step three is one of ethylene-vinyl acetate copolymer and ethylene-α-olefin copolymer.

[0016] As a further solution of the present invention: the melt extrusion temperature of the No. 1 extruder in step three is 230-250°C.

[0017] As a further solution of the present invention: the melt extrusion temperature of the No. 2 extruder is 230-250°C.

[0018] As a further solution of the present invention: the melt extrusion temperature of the No. 3 extruder is 180-230°C.

[0019] As a further solution of the present invention: the melt extrusion temperature of the No. 4 extruder is 180-230°C.

[0020] As a further solution of the present invention: the solvent-free composite polypropylene film is a four-layer structure formed by sequentially stacking and co-extruding an anti-adhesive layer, a supporting layer, a connecting layer and an adhesive layer.

[0021] As a further solution of the present invention: the thickness of the anti-adhesion layer is 1.0-2.0 μm.

[0022] As a further solution of the present invention: the thickness of the support layer is 10-15 μm.

[0023] As a further solution of the present invention: the thickness of the connecting layer is 1.0-3.0 μm.

[0024] As a further solution of the present invention: the thickness of the adhesive layer is 2.0-6.0 μm.

[0025] As a further solution of the present invention: the modified polypropylene is prepared by the following steps:

[0026] Step s1: Add nadic anhydride, N,N-dimethylethanolamine, phosphoric acid, hydroquinone and toluene into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 20-25° C. and a stirring rate of 300-400 r / min, then heat to reflux and continue stirring and reacting for 6-8 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation to obtain intermediate 1;

[0027] Step s2: Add intermediate 1, 1-bromodecane and anhydrous acetonitrile to a three-necked flask equipped with a stirrer, a thermometer and an air duct, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 20-25° C. and a stirring rate of 300-400 r / min, then heat to 45-50° C. and continue stirring and reacting for 20-30 hours. After the reaction is completed, cool the reaction product to room temperature, pour it into ice ether, stand it for precipitation, and then vacuum filter it, place the filter cake in a vacuum drying oven, and dry it at a temperature of 45-50° C. for 3-5 hours to obtain intermediate 2;

[0028] Step s3: Add intermediate 2, azobisisobutyronitrile and anhydrous tetrahydrofuran into a three-necked flask equipped with a stirrer, a thermometer and an air duct, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 20-25°C and a stirring rate of 300-400r / min, then heat to 55-60°C and continue stirring and reacting for 6-8 hours. After the reaction is completed, cool the reaction product to room temperature, pour it into ice ether, let it stand to precipitate, and then vacuum filter. Place the filter cake in a vacuum drying oven and dry it at a temperature of 45-50°C for 3-5 hours to obtain intermediate 3;

[0029] Step s4: Add intermediate 3, silver p-toluenesulfonate, dimethyl sulfoxide and nitromethane to a three-necked flask equipped with a stirrer, a thermometer and an air duct, introduce nitrogen protection, stir and react for 40-50 minutes at a temperature of -5-0°C and a stirring rate of 300-400r / min, then heat to 25-30°C and continue stirring and reacting for 1-1.5 hours. After the reaction is completed, pour the reaction product into ice ether, let it stand to precipitate, then vacuum filter, place the filter cake in a vacuum drying oven, and dry it at a temperature of 25-30°C for 10-15 hours to obtain a composite antibacterial material;

[0030] Step s5: Add polypropylene and composite antibacterial material into a mixer, stir and react for 10-20 minutes at a temperature of 20-25°C and a stirring rate of 100-150r / min, then add into an extruder, melt-extrude at a temperature of 180-220°C, and obtain modified polypropylene after water cooling and pelletizing.

[0031] As a further solution of the present invention: the usage ratio of the nadic anhydride, N,N-dimethylethanolamine, phosphoric acid, hydroquinone and toluene in step s1 is 10 mmol: 22-25 mmol: 2-3 mL: 0.01-0.02 g: 50-60 mL.

[0032] As a further solution of the present invention: the usage ratio of the intermediate 1, 1-bromodecane and anhydrous acetonitrile in step s2 is 10 mmol: 20-22 mmol: 50-60 mL.

[0033] As a further solution of the present invention: the usage ratio of the intermediate 2, azobisisobutyronitrile and anhydrous tetrahydrofuran in step s3 is 10 g: 0.01-0.02 g: 90-100 mL.

[0034] As a further solution of the present invention: the usage ratio of the intermediate 3, silver p-toluenesulfonate, dimethyl sulfoxide and nitromethane in step s4 is 10 g: 0.5-1.3 g: 50-60 mL: 50-60 mL.

[0035] As a further solution of the present invention: the usage ratio of the polypropylene and the composite antibacterial material in step s5 is 10g:0.1-1.5g; the polypropylene is PP homopolymer polypropylene North China Petrochemical HB28F.

[0036] Beneficial effects of the present invention:

[0037] The invention discloses a method for preparing a solvent-free composite polypropylene film, comprising the steps of: adding an anti-adhesive raw material, a supporting raw material, a connecting raw material and an adhesive raw material to a No. 1 extruder, a No. 2 extruder, a No. 3 extruder and a No. 4 extruder respectively and sequentially for melt extrusion; filtering the raw materials through a 320-mesh filter and sequentially converging the raw materials into a die head of a four-layer structure; extruding the four-layer composite thick sheet; cooling the four-layer composite thick sheet by cooling water; stretching the four-layer composite thick sheet to form a film; cooling the film by air showering; and then performing a corona treatment to obtain a film mother roll; performing an aging treatment, slitting and packaging the film mother roll to obtain a solvent-free composite polypropylene film; the preparation method adopts a hot pressing melt compounding method to form a four-layer structure; The solvent-free composite polypropylene film with the structure has good mechanical strength, and can be directly composited with other materials (such as paper, plastic, metal, and wood panels) by heating without using any adhesive. The composite fastness is strong and the operation is convenient. No organic solvent is required in the production process, which significantly reduces the production cost and effectively reduces the environmental pollution caused by the volatilization of organic solvents. At the same time, the modified polypropylene has excellent antibacterial properties, which significantly improves the anti-mold ability of the film, resists mold erosion for a long time, and prolongs the service life of the product. This makes the film have a wide range of application prospects in many fields, providing strong support for improving product quality and protecting user health.

[0038] In the process of preparing solvent-free composite polypropylene film, a modified polypropylene is first prepared. First, nadic anhydride and N, N-dimethylethanolamine are reacted, and the anhydride group on the nadic anhydride reacts with the hydroxyl group on the N, N-dimethylethanolamine to introduce a tertiary amine group to obtain an intermediate 1. Then, the intermediate 1 and 1-bromodecane are reacted, and the tertiary amine group on the intermediate 1 reacts with the bromine atom on the 1-bromodecane to form a quaternary ammonium group, forming an organic ammonium bromide ammonium salt to obtain an intermediate 2. Then, the intermediate 2 is polymerized to form a polymer, and the number of quaternary ammonium groups is increased to obtain an intermediate The present invention relates to a method for preparing a composite antibacterial material, wherein the intermediate 3 is reacted with silver p-toluenesulfonate, and the bromide ions on the intermediate 3 and the silver ions on the silver p-toluenesulfonate are in situ precipitated to form silver bromide, thereby improving the stability of the silver ions and reducing the loss rate of the silver ions, thereby obtaining a composite antibacterial material, and finally the composite antibacterial material is used to blend and modify polypropylene to obtain modified polypropylene; the molecular structure of the composite antibacterial material in the modified polypropylene contains a large number of quaternary ammonium groups and silver bromide particles, and the synergistic effect of the two gives it excellent antibacterial properties, effectively controls the growth and spread of harmful microorganisms, and effectively improves the hygienic properties of the solvent-free composite polypropylene film. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be further described below in conjunction with the accompanying drawings.

[0040] Figure 1 It is a schematic structural diagram of the solvent-free composite polypropylene film of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the 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. Example

[0042] This embodiment is a method for preparing a solvent-free composite polypropylene film, comprising the following steps:

[0043] Step S1: 10 mmol of nadic anhydride, 22 mmol of N,N-dimethylethanolamine, 2 mL of phosphoric acid, 0.01 g of hydroquinone and 50 mL of toluene were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at a temperature of 20° C. and a stirring rate of 300 r / min for 20 min, and then the temperature was raised to reflux and the stirring reaction was continued for 6 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation to obtain intermediate 1;

[0044] Step S2: 10 mmol of intermediate 1, 20 mmol of 1-bromodecane and 50 mL of anhydrous acetonitrile were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The mixture was stirred at 20° C. and a stirring rate of 300 r / min for 20 min, and then the mixture was heated to 45° C. and continued to stir for 20 h. After the reaction was completed, the reaction product was cooled to room temperature, and then poured into ice ether, and allowed to stand for precipitation, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 45° C. for 3 h to obtain intermediate 2;

[0045] Step S3: 10 g of intermediate 2, 0.01 g of azobisisobutyronitrile and 90 mL of anhydrous tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer and a gas duct, and nitrogen was introduced for protection. The mixture was stirred at 20° C. and a stirring rate of 300 r / min for 20 min, and then the mixture was heated to 55° C. and stirred for 6 h. After the reaction, the reaction product was cooled to room temperature, poured into ice ether, and allowed to stand for precipitation. The mixture was then vacuum filtered, and the filter cake was placed in a vacuum drying oven and dried at 45° C. for 3 h to obtain intermediate 3;

[0046] Step S4: 10 g of intermediate 3, 0.5 g of silver p-toluenesulfonate, 50 mL of dimethyl sulfoxide and 50 mL of nitromethane were added to a three-necked flask equipped with a stirrer, a thermometer and an air duct, and nitrogen was introduced for protection. The mixture was stirred at a temperature of -5 ° C and a stirring rate of 300 r / min for 40 min, and then the temperature was raised to 25 ° C and the stirring reaction was continued for 1 h. After the reaction was completed, the reaction product was poured into ice ether, allowed to stand for precipitation, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at a temperature of 25 ° C for 10 h to obtain a composite antibacterial material;

[0047] Step S5: 99% of Huabei Petrochemical HB28F polypropylene and 1% of the composite antibacterial material are weighed according to the mass ratio and added into a mixer, stirred and reacted for 20 minutes at a temperature of 20° C. and a stirring rate of 100 r / min, then added into an extruder, melt-extruded at a temperature of 180° C., water-cooled, and pelletized to obtain modified polypropylene;

[0048] Step S6: weighing 95% of modified polypropylene and 5% of anti-blocking agent according to the mass ratio, and uniformly mixing the modified polypropylene and the anti-blocking agent to obtain an anti-blocking raw material; the anti-blocking agent is silicon dioxide;

[0049] Step S7: Weigh 94% of modified polypropylene and 6% of antistatic masterbatch according to the mass ratio, and mix the modified polypropylene and the antistatic masterbatch evenly to obtain a supporting raw material; the antistatic masterbatch is Konstanp AT4030PP;

[0050] Step S8: adding the anti-adhesion raw material, the supporting raw material, the connecting raw material and the adhesive raw material to the No. 1 extruder, the No. 2 extruder, the No. 3 extruder and the No. 4 extruder respectively for melt extrusion, filtering through a 320-mesh filter and then converging into a die head of a four-layer structure, and extruding to form a four-layer composite thick sheet; the connecting raw material is high-pressure polyethylene; the adhesive raw material is ethylene-vinyl acetate copolymer (DuPont 670, USA); the melt extrusion temperature of the No. 1 extruder is 230° C.; the melt extrusion temperature of the No. 2 extruder is 230° C.; the melt extrusion temperature of the No. 3 extruder is 180° C.; the melt extrusion temperature of the No. 4 extruder is 180° C.;

[0051] Step S9: The four-layer composite thick sheet is cooled to 30°C by cooling water, and then longitudinally stretched under the conditions of 95-130°C in the preheating zone, 100°C in the stretching zone, and a longitudinal stretching ratio of 4.7, and then transversely stretched under the conditions of 160-165°C in the preheating zone, 153°C in the stretching zone, and a transverse stretching ratio of 8 times to form a film, which is then cooled by air shower and then subjected to corona treatment at a power of 18Wmin / m 2The corona treatment is carried out under the conditions of , and the film mother roll is harvested. The film mother roll is subjected to aging treatment, slitting, and packaging to obtain a film. Figure 1 Solvent-free laminated polypropylene film shown. Example

[0052] This embodiment is a method for preparing a solvent-free composite polypropylene film, comprising the following steps:

[0053] Step S1: 10 mmol of nadic anhydride, 24 mmol of N,N-dimethylethanolamine, 2.5 mL of phosphoric acid, 0.015 g of hydroquinone and 55 mL of toluene were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at a temperature of 22° C. and a stirring rate of 350 r / min for 25 min, and then the temperature was raised to reflux and the stirring reaction was continued for 7 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation to obtain intermediate 1;

[0054] Step S2: 10 mmol of intermediate 1, 21 mmol of 1-bromodecane and 55 mL of anhydrous acetonitrile were added to a three-necked flask equipped with a stirrer, a thermometer and a gas duct, and nitrogen was introduced for protection. The mixture was stirred at 22° C. and a stirring rate of 350 r / min for 25 min, and then the mixture was heated to 48° C. and stirred for 25 h. After the reaction, the reaction product was cooled to room temperature, poured into ice ether, and allowed to stand for precipitation. The mixture was then vacuum filtered, and the filter cake was placed in a vacuum drying oven and dried at 48° C. for 4 h to obtain intermediate 2;

[0055] Step S3: 10 g of intermediate 2, 0.015 g of azobisisobutyronitrile and 95 mL of anhydrous tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The mixture was stirred at 22° C. and a stirring rate of 350 r / min for 25 min, and then the mixture was heated to 58° C. and continued to stir for 7 h. After the reaction, the reaction product was cooled to room temperature, poured into ice ether, and allowed to stand for precipitation. The mixture was then vacuum filtered, and the filter cake was placed in a vacuum drying oven and dried at 48° C. for 4 h to obtain intermediate 3;

[0056] Step S4: 10 g of intermediate 3, 0.9 g of silver p-toluenesulfonate, 55 mL of dimethyl sulfoxide and 55 mL of nitromethane were added to a three-necked flask equipped with a stirrer, a thermometer and an air duct, and nitrogen was introduced for protection. The mixture was stirred at a temperature of -3 ° C and a stirring rate of 350 r / min for 45 min, and then the temperature was raised to 28 ° C and the stirring reaction was continued for 1.2 h. After the reaction was completed, the reaction product was poured into ice ether, allowed to stand for precipitation, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at a temperature of 28 ° C for 12 h to obtain a composite antibacterial material;

[0057] Step S5: 93% of HB28F polypropylene from North China Petrochemical and 7% of the composite antibacterial material were weighed according to the mass ratio and added into a mixer, stirred and reacted for 15 minutes at a temperature of 22° C. and a stirring rate of 130 r / min, and then added into an extruder, melt-extruded at a temperature of 200° C., water-cooled, and pelletized to obtain modified polypropylene;

[0058] Step S6: Weigh 97% of modified polypropylene and 3% of anti-blocking agent according to the mass ratio, and mix the modified polypropylene and the anti-blocking agent evenly to obtain an anti-blocking raw material; the anti-blocking agent is a glass microbead masterbatch;

[0059] Step S7: Weigh 96% of modified polypropylene and 4% of antistatic masterbatch according to the mass ratio, and mix the modified polypropylene and the antistatic masterbatch evenly to obtain a supporting raw material; the antistatic masterbatch is Best AS2335PP;

[0060] Step S8: adding the anti-adhesion raw material, the supporting raw material, the connecting raw material and the adhesive raw material to the No. 1 extruder, the No. 2 extruder, the No. 3 extruder and the No. 4 extruder respectively for melt extrusion, filtering through a 320-mesh filter and then converging into a die head of a four-layer structure to extrude and form a four-layer composite thick sheet; the connecting raw material is ethylene-vinyl acetate; the adhesive raw material is ethylene-α-olefin copolymer (ENGAGE 7467 of Dow Chemical, USA); the melt extrusion temperature of the No. 1 extruder is 240° C.; the melt extrusion temperature of the No. 2 extruder is 240° C.; the melt extrusion temperature of the No. 3 extruder is 205° C.; the melt extrusion temperature of the No. 4 extruder is 205° C.;

[0061] Step S9: The four-layer composite thick sheet is cooled to 32°C by cooling water, and then longitudinally stretched under the conditions of 98-132°C in the preheating zone, 105°C in the stretching zone, and a longitudinal stretching ratio of 4.7, and then transversely stretched under the conditions of 165-168°C in the preheating zone, 155°C in the stretching zone, and a transverse stretching ratio of 8 times to form a film, which is then cooled by air shower and then corona treated at a power of 26Wmin / m 2The corona treatment is carried out under the conditions of , and the film mother roll is harvested. The film mother roll is subjected to aging treatment, slitting, and packaging to obtain a film. Figure 1 Solvent-free laminated polypropylene film shown. Example

[0062] This embodiment is a method for preparing a solvent-free composite polypropylene film, comprising the following steps:

[0063] Step S1: 10 mmol of nadic anhydride, 25 mmol of N,N-dimethylethanolamine, 3 mL of phosphoric acid, 0.02 g of hydroquinone and 60 mL of toluene were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at a temperature of 25° C. and a stirring rate of 400 r / min for 30 min, and then the temperature was raised to reflux and the stirring reaction was continued for 8 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation to obtain intermediate 1;

[0064] Step S2: 10 mmol of intermediate 1, 22 mmol of 1-bromodecane and 60 mL of anhydrous acetonitrile were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The mixture was stirred at 25° C. and a stirring rate of 400 r / min for 30 min, and then the mixture was heated to 50° C. and continued to stir for 30 h. After the reaction was completed, the reaction product was cooled to room temperature, and then poured into ice ether, and allowed to stand for precipitation, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 50° C. for 5 h to obtain intermediate 2;

[0065] Step S3: 10 g of intermediate 2, 0.02 g of azobisisobutyronitrile and 100 mL of anhydrous tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer and a gas duct, and nitrogen was introduced for protection. The mixture was stirred at 25° C. and a stirring rate of 400 r / min for 30 min, and then the mixture was heated to 60° C. and the stirring reaction was continued for 8 h. After the reaction was completed, the reaction product was cooled to room temperature, and then poured into ice ether, and allowed to stand for precipitation, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 50° C. for 5 h to obtain intermediate 3;

[0066] Step S4: 10 g of intermediate 3, 1.3 g of silver p-toluenesulfonate, 60 mL of dimethyl sulfoxide and 60 mL of nitromethane were added to a three-necked flask equipped with a stirrer, a thermometer and an air duct, and nitrogen was introduced for protection. The mixture was stirred at 0°C and a stirring rate of 400 r / min for 50 min, and then the mixture was heated to 30°C and the stirring reaction was continued for 1.5 h. After the reaction was completed, the reaction product was poured into ice ether, allowed to stand for precipitation, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 30°C for 15 h to obtain a composite antibacterial material;

[0067] Step S5: 87% of HB28F polypropylene from North China Petrochemical and 13% of the composite antibacterial material were weighed according to the mass ratio and added into a mixer, stirred and reacted for 20 minutes at a temperature of 25° C. and a stirring rate of 150 r / min, and then added into an extruder, melt-extruded at a temperature of 220° C., water-cooled, and pelletized to obtain modified polypropylene;

[0068] Step S6: weighing 98% of modified polypropylene and 2% of anti-blocking agent according to the mass ratio, and mixing the modified polypropylene and the anti-blocking agent evenly to obtain an anti-blocking raw material; the anti-blocking agent is polymethyl methacrylate;

[0069] Step S7: Weigh 98% of modified polypropylene and 2% of antistatic masterbatch according to the mass ratio, and mix the modified polypropylene and the antistatic masterbatch evenly to obtain a supporting raw material; the antistatic masterbatch is excellent FAS25PP;

[0070] Step S8: adding the anti-adhesion raw material, the supporting raw material, the connecting raw material and the adhesive raw material to the No. 1 extruder, the No. 2 extruder, the No. 3 extruder and the No. 4 extruder respectively for melt extrusion, filtering through a 320-mesh filter and then converging into a die head of a four-layer structure to extrude and form a four-layer composite thick sheet; the connecting raw material is ethylene-ethyl acrylate copolymer; the adhesive raw material is ethylene-α-olefin copolymer (ethylene-butene copolymer EXACT POE9061 of ExxonMobil, USA); the melt extrusion temperature of the No. 1 extruder is 250° C.; the melt extrusion temperature of the No. 2 extruder is 250° C.; the melt extrusion temperature of the No. 3 extruder is 230° C.; the melt extrusion temperature of the No. 4 extruder is 230° C.;

[0071] Step S9: The four-layer composite thick sheet is cooled to 35°C by cooling water, and then longitudinally stretched under the conditions of 100-136°C in the preheating zone, 108°C in the stretching zone, and a longitudinal stretching ratio of 4.7, and then transversely stretched under the conditions of 166-170°C in the preheating zone, 157°C in the stretching zone, and a transverse stretching ratio of 8 times to form a film, which is then cooled by air shower and then subjected to corona treatment at a power of 30Wmin / m2 The corona treatment is carried out under the conditions of , and the film mother roll is harvested. The film mother roll is subjected to aging treatment, slitting, and packaging to obtain a film. Figure 1 Solvent-free laminated polypropylene film shown.

[0072] Comparative Example 1

[0073] This comparative example is a method for preparing a solvent-free composite polypropylene film, comprising the following steps:

[0074] Step S1: weighing 98% of HB28F polypropylene and 2% of anti-blocking agent produced by North China Petrochemical Corporation according to the mass ratio, and mixing the polypropylene and the anti-blocking agent evenly to obtain an anti-blocking raw material; the anti-blocking agent is a silica masterbatch;

[0075] Step S2: weighing 98% of HB28F polypropylene from North China Petrochemical and 2% of antistatic masterbatch according to the mass ratio, and evenly mixing the polypropylene and the antistatic masterbatch to obtain a supporting raw material; the antistatic masterbatch is a fine FAS25PP;

[0076] Step S3: adding the anti-adhesion raw material, the supporting raw material, the connecting raw material and the adhesive raw material to the No. 1 extruder, the No. 2 extruder, the No. 3 extruder and the No. 4 extruder respectively for melt extrusion, filtering through a 320-mesh filter and then converging into a die head of a four-layer structure to extrude and form a four-layer composite thick sheet; the connecting raw material is ethylene-ethyl acrylate copolymer; the adhesive raw material is ethylene-α-olefin copolymer (ethylene-butene copolymer EXACT POE9061 of ExxonMobil, USA); the melt extrusion temperature of the No. 1 extruder is 250° C.; the melt extrusion temperature of the No. 2 extruder is 250° C.; the melt extrusion temperature of the No. 3 extruder is 230° C.; the melt extrusion temperature of the No. 4 extruder is 230° C.;

[0077] Step S4: The four-layer composite thick sheet is cooled to 35°C by cooling water, and then longitudinally stretched under the conditions of 100-134°C in the preheating zone, 106°C in the stretching zone, and a longitudinal stretching ratio of 4.7, and then transversely stretched under the conditions of 165-168°C in the preheating zone, 156°C in the stretching zone, and a transverse stretching ratio of 8 times to form a film, which is then cooled by air shower and then subjected to corona treatment at a power of 35Wmin / m 2 The corona treatment is carried out under the conditions of , and the film mother roll is harvested. The film mother roll is subjected to aging treatment, slitting, and packaging to obtain a film. Figure 1 Solvent-free laminated polypropylene film shown.

[0078] The properties of the solvent-free composite polypropylene films in Examples 1-3 and Comparative Example 1 were tested, and the thickness of the anti-blocking layer in the solvent-free composite polypropylene film was controlled to be 1.5±0.15 μm, the thickness of the support layer was 12.5±0.15 μm, the thickness of the connecting layer was 1.5±0.15 μm, and the thickness of the adhesive layer was 3.0±0.15 μm. The test results are as follows:

[0079] Tensile strength: Sample preparation and determination shall be carried out in accordance with the method specified in GB / T 1040.3-2006;

[0080] Antifungal performance: The solvent-free composite polypropylene film was spread flat on the culture dish, and then the culture medium containing the same number of live mold colonies was coated on the solvent-free composite polypropylene film. The culture dish was then placed in an incubator for 48 hours. After the incubation, the number of colonies was calculated, and the antifungal rate η against mold was calculated according to the following formula:

[0081]

[0082] Where:

[0083] C0 is the initial mold colony count;

[0084] C1 is the number of mold colonies after 48 h;

[0085] Among them, the molds used in the test were Aspergillus flavus and Aspergillus niger;

[0086] The test results are shown in the following table:

[0087] .

[0088] Referring to the data in the above table, based on the comparison between Examples 1-3 and Comparative Example 1, it can be seen that the solvent-free composite polypropylene film of the present application has excellent mechanical properties and antifungal properties, outstanding performance, and broad application prospects.

[0089] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0090] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing a solvent-free composite polypropylene film, characterized in that: The following steps are involved: Step 1: Weigh 95-98% of modified polypropylene and 2-5% of anti-adhesive agent according to the mass ratio, and mix the modified polypropylene and anti-adhesive agent evenly to obtain an anti-adhesive raw material; the anti-adhesive agent is one of silicon dioxide, glass beads, calcium carbonate, calcined silica, kaolin, and polymethyl methacrylate; Step 2: Weigh 94-98% of modified polypropylene and 2-6% of antistatic masterbatch according to the mass ratio, and mix the modified polypropylene and the antistatic masterbatch evenly to obtain a supporting raw material; the antistatic masterbatch is one of Konstanp AT4030PP, Best AS2335PP and FAS25PP; Step 3: adding the anti-adhesion raw material, the supporting raw material, the connecting raw material and the adhesive raw material to the No. 1 extruder, the No. 2 extruder, the No. 3 extruder and the No. 4 extruder respectively and sequentially for melt extrusion, filtering through a 320-mesh filter and sequentially converging into a die head of a four-layer structure, and extruding to form a four-layer composite thick sheet; the connecting raw material is one of high-pressure polyethylene, ethylene-vinyl acetate, ethylene-acrylic acid copolymer and ethylene-ethyl acrylate copolymer; the adhesive raw material is one of ethylene-vinyl acetate copolymer and ethylene-α-olefin copolymer; Step 4: The four-layer composite thick sheet is cooled to 30-35°C by cooling water, and then longitudinally stretched at a longitudinal stretching process temperature of 95-138°C, with a longitudinal stretching ratio of 4.7-5.1, and then transversely stretched at a transverse stretching process temperature of 150-170°C, with a transverse stretching ratio of 8-10 times to form a film. The film is cooled by air shower and then corona treated at a power of 18-35Wmin / m 2 The corona treatment is carried out under the condition of , and the film mother roll is harvested. The film mother roll is subjected to aging treatment, slitting, and packaging to obtain a solvent-free composite polypropylene film; Wherein, the modified polypropylene is prepared by the following steps: Step s1: stirring and reacting nadic anhydride, N,N-dimethylethanolamine, phosphoric acid, hydroquinone and toluene, cooling the reaction product after the reaction, and then rotary evaporating to obtain intermediate 1; the amount ratio of nadic anhydride, N,N-dimethylethanolamine, phosphoric acid, hydroquinone and toluene is 10mmol:22-25mmol:2-3mL:0.01-0.02g:50-60mL; Step s2: stirring the intermediate 1, 1-bromodecane and anhydrous acetonitrile to react, cooling the reaction product after the reaction, and then pouring it into ice ether, standing it to precipitate, and then vacuum filtering it, drying the filter cake to obtain the intermediate 2; the amount ratio of the intermediate 1, 1-bromodecane and anhydrous acetonitrile is 10mmol:20-22mmol:50-60mL; Step s3: stirring the intermediate 2, azobisisobutyronitrile and anhydrous tetrahydrofuran for reaction, cooling the reaction product after the reaction, and then pouring it into ice ether, standing to precipitate, and then vacuum filtering, drying the filter cake to obtain the intermediate 3; the amount ratio of the intermediate 2, azobisisobutyronitrile and anhydrous tetrahydrofuran is 10g:0.01-0.02g:90-100mL; Step s4: stirring the intermediate 3, silver p-toluenesulfonate, dimethyl sulfoxide and nitromethane for reaction, pouring the reaction product into ice ether after the reaction is completed, standing to precipitate, then vacuum filtering, drying the filter cake to obtain a composite antibacterial material; the amount ratio of the intermediate 3, silver p-toluenesulfonate, dimethyl sulfoxide and nitromethane is 10g: 0.5-1.3g: 50-60mL: 50-60mL; Step s5: adding polypropylene and the composite antibacterial material into a mixer for stirring reaction, then adding them into an extruder for melt extrusion, water cooling and pelletizing to obtain modified polypropylene; the dosage ratio of the polypropylene and the composite antibacterial material is 10g:0.1-1.5g.

2. The method for preparing a solvent-free composite polypropylene film according to claim 1, characterized in that: The melt extrusion temperature of the No. 1 extruder in step 3 is 230-250°C; the melt extrusion temperature of the No. 2 extruder is 230-250°C; the melt extrusion temperature of the No. 3 extruder is 180-230°C; and the melt extrusion temperature of the No. 4 extruder is 180-230°C.

3. The method for preparing a solvent-free composite polypropylene film according to claim 1, characterized in that: The solvent-free composite polypropylene film is a four-layer structure formed by sequentially stacking and co-extruding an anti-adhesive layer, a supporting layer, a connecting layer and an adhesive layer.

4. The method for preparing a solvent-free composite polypropylene film according to claim 3, characterized in that: The thickness of the anti-adhesion layer is 1.0-2.0 μm, the thickness of the support layer is 10-15 μm, the thickness of the connection layer is 1.0-3.0 μm, and the thickness of the adhesive layer is 2.0-6.0 μm.

5. The method for preparing a solvent-free composite polypropylene film according to claim 1, characterized in that: The polypropylene is homopolymer polypropylene, which is HB28F from North China Petrochemical.

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