CN113024863A - Ultrathin BOPP printing bag making film and preparation method thereof - Google Patents

Ultrathin BOPP printing bag making film and preparation method thereof Download PDF

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Publication number
CN113024863A
CN113024863A CN202110448236.1A CN202110448236A CN113024863A CN 113024863 A CN113024863 A CN 113024863A CN 202110448236 A CN202110448236 A CN 202110448236A CN 113024863 A CN113024863 A CN 113024863A
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bopp
film
mixture
stretching
mass
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翁晓锋
帖玮婷
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Zhejiang Lanye Film Co ltd
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Zhejiang Lanye Film Co ltd
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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18Manufacture of films or sheets
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/10Homopolymers or copolymers of propene
    • C08J2323/12Polypropene
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2447/00Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds; Derivatives of such polymers

Abstract

The invention relates to a BOPP printing bag making film, and discloses an ultrathin BOPP printing bag making film and a preparation method thereof, wherein the preparation method comprises the following steps: preparing a propylene polymer, uniformly mixing the propylene polymer with polyisoprene according to the mass ratio of 6-8:1, then obtaining mixed slurry through a casting machine, and adding 10-15% of modified plant fiber in percentage by mass into the mixed slurry; and adding a mixture of a thickening agent and a compatilizer with the mass percent of 5-8%, and finally obtaining the ultrathin BOPP printing bag making film after extrusion, stretching, slicing, corona, printing and rolling. According to the invention, the finally prepared BOPP printing bag-making film has good strength and toughness on the premise of being thin enough by preparing the stretching casting sheet with excellent stretching performance, good elasticity and good ductility.

Description

Ultrathin BOPP printing bag making film and preparation method thereof
Technical Field
The invention relates to a BOPP printing bag making film, in particular to an ultrathin BOPP printing bag making film and a preparation method thereof.
Background
BOPP film is a very important flexible packaging material, and after corona treatment, it has good printing adaptability, and can be color-register printed to obtain exquisite appearance effect, so it is often used as surface layer material of composite film.
The balance between the thinness and the strength of the BOPP film in the production process is always the key point pursued in the field, and in the prior art, many thin films have poor strength and toughness, and the thin film with good strength is thick, so that the problem to be solved in the field is needed to prepare the ultrathin BOPP printing bag making film with good tensile strength and good elasticity.
Disclosure of Invention
The invention provides an ultrathin BOPP printing bag making film and a preparation method thereof, aiming at the problems of the BOPP printing bag making film in the prior art.
In order to solve the technical problem, the invention is solved by the following technical scheme:
the preparation method of the ultrathin BOPP printing bag making film comprises the following steps:
step one, preparing a propylene polymer by using a propylene monomer;
step two, uniformly mixing the propylene polymer and polyisoprene in the step one according to the mass ratio of 6-8:1 to obtain a mixture A;
step three, the mixture A in the step two is processed by a casting machine to obtain mixed slurry, and the processing temperature in the casting machine is 160-200 ℃;
step four, adding 10-15% by mass of modified plant fibers into the mixed slurry, and uniformly mixing to obtain a mixture B; wherein, the modified plant fiber is prepared by putting natural plant fiber into 10-20% sodium hydroxide for water bath treatment for 1h, the water bath treatment temperature is 60 ℃, and after treatment, centrifugal dealkalization treatment is carried out until the alkali content in the natural plant fiber is 30-40%; then soaking the natural plant fiber subjected to alkali treatment in a glutaraldehyde solution for 10h, placing the soaked natural plant fiber in water with the temperature of 150-180 ℃ for hydrothermal reaction, and cooling to obtain modified plant fiber;
step five, adding a mixture of 5-8% by mass of a thickening agent and a compatilizer into the mixture B, controlling the temperature in the mixing chamber to be 170-200 ℃ during mixing, and the mixing time to be 10-15min, then introducing nitrogen into the mixing chamber, controlling the pressure in the mixing chamber to be 0.15MPa, raising the temperature in the mixing chamber to be 400-450 ℃ at the speed of 10 ℃/min, preserving the heat for 12mim, and then cooling to 180-220 ℃ to obtain a mixture C;
sixthly, putting the mixture C into an extruder to be extruded to obtain a tensile casting sheet;
and step seven, placing the stretched casting sheet in a biaxial stretching device for stretching, and obtaining the ultrathin BOPP printing bag making film after slicing, corona, printing and rolling after stretching.
Preferably, the preparation method of the propylene polymer in the first step comprises the following steps: carrying out polymerization reaction on propylene monomers in a deionized water reaction kettle with the reaction pressure of 0.6MPa and the temperature of 3-5 ℃, and adding ammonium persulfate and ferrous sulfate in sequence in the polymerization reaction process.
Preferably, the mass of the ammonium persulfate is 0.5% of the mass of the deionized water, and the mass of the ferrous sulfate is 0.25% of the mass of the deionized water.
Preferably, the hydrothermal reaction time in the fourth step is 10-14 h.
Preferably, in the mixture of the thickening agent and the compatilizer in the step five, the mass ratio of the thickening agent to the compatilizer is 20-25: 1.
The ultrathin BOPP printing bag making film is prepared by the preparation method of the ultrathin BOPP printing bag making film.
Due to the adoption of the technical scheme, the invention has the remarkable technical effects that:
according to the invention, the finally prepared BOPP printing bag-making film has good strength and toughness on the premise of being thin enough by preparing the stretching casting sheet with excellent stretching performance, good elasticity and good ductility.
Drawings
Fig. 1 is a schematic structural diagram of embodiment 5 of the present invention.
Fig. 2 is a schematic view of the structure of fig. 1 with the upper end plate removed.
Fig. 3 is a schematic structural diagram of the film limiting mechanism in fig. 1.
Fig. 4 is a cross-sectional view of the movable roller of fig. 1.
Fig. 5 is a schematic structural diagram of a limiting block in fig. 4.
FIG. 6 is a schematic diagram of the slider shown in FIG. 4.
Fig. 7 is a distribution diagram of a BOPP film when stretched in the machine direction.
Fig. 8 is a distribution diagram of a BOPP film when stretched in the transverse direction.
Detailed Description
Example 1
The preparation method of the ultrathin BOPP printing bag making film comprises the following steps:
step one, preparing a propylene polymer; the preparation method of the propylene polymer in this example is as follows: carrying out polymerization reaction on propylene monomers in a deionized water reaction kettle with the reaction pressure of 0.6MPa and the temperature of 3-5 ℃, and adding ammonium persulfate and ferrous sulfate in sequence in the polymerization reaction process. Wherein the mass of the ammonium persulfate is 0.5 percent of the mass of the deionized water, and the mass of the ferrous sulfate is 0.25 percent of the mass of the deionized water.
Ammonium persulfate has strong oxidizing property and is easy to dissolve in water emulsion, and is used as an initiator for polymerizing a propylene monomer into a propylene polymer, and the obtained propylene polymer has good water resistance; ferrous sulfate is used as a polymerization catalyst, a propylene monomer is fully contacted with deionized water containing an initiator, a polymerization catalyst and other auxiliaries, the resin performance is good, the average tensile strength of the finally obtained propylene polymer can reach more than 40MPa, and the tensile strength of the finally obtained foam material can be effectively improved by using the propylene polymer with better tensile strength as a raw material of the foam material.
In this example, an olefin polymerization catalyst having main components including titanium, magnesium, chlorine and an electron donor was further added during the preparation of the propylene polymer.
Step two, uniformly mixing the propylene polymer and polyisoprene in the step one according to the mass ratio of 6:1 to obtain a mixture A; in the embodiment, polyisoprene is added into the raw material for preparation, so that the polyisoprene has very good tensile property and higher tensile strength, and can provide a good premise guarantee for the subsequent stretching of the cast sheet, so that a thin film with higher strength can be stretched in the subsequent stretching process.
Step three, the mixture A in the step two is processed by a casting machine to obtain mixed slurry, and the processing temperature in the casting machine is 180 ℃; through making its preliminary treatment for being the mixture of thick liquids state with mixture A through the casting machine in this embodiment, make its can with the plant fiber of follow-up addition can be better mix for modified plant fiber can be more abundant fuse to mixture A in, make the tensile casting piece texture that makes more even, plant fiber can evenly distributed everywhere in tensile casting piece, then effectively improve the tensile homogeneity of film.
Step four, adding 10% by mass of modified plant fibers into the mixed slurry, and uniformly mixing to obtain a mixture B;
wherein, the modified plant fiber is prepared by putting natural plant fiber into 10% sodium hydroxide for water bath treatment for 1h, the water bath treatment temperature is 60 ℃, and after treatment, centrifugal dealkalization treatment is carried out until the alkali content in the natural plant fiber is 30%; then soaking the natural plant fiber subjected to alkali treatment in a glutaraldehyde solution for 10 hours, placing the natural plant fiber in water at 150 ℃ for hydrothermal reaction for 12 hours after soaking, and cooling to obtain modified plant fiber;
in the embodiment, the modified plant fiber is added into the mixed slurry, so that the structural strength of the film material can be effectively improved, the tensile property and the elastic property of the film material can be better improved, wherein the added plant fiber is modified plant fiber, which is firstly treated by sodium hydroxide to change the tensile property of the plant fiber and greatly improve the tensile strength of the final film material, and the dealkalized plant fiber still contains 30 percent of sodium hydroxide when being soaked by glutaraldehyde, thereby forming alkaline glutaraldehyde, which can protect the hollow structure of the plant fiber from being damaged and not easy to collapse, and can change the groups on the surface of the plant fiber by carrying out hydrothermal reaction after being soaked by alkaline glutaraldehyde, the obtained mixture B has hydrophilic performance and oleophilic performance, so that the elasticity and the tensile property of the mixture B are further improved.
Step five, adding a mixture of 6 mass percent of thickening agent and compatilizer into the mixture B, controlling the mass ratio of the thickening agent to the compatilizer in the mixture of the thickening agent and the compatilizer to be 22:1, controlling the temperature in a mixing chamber to be 190 ℃ during mixing, mixing for 12min, introducing nitrogen into the mixing chamber, controlling the pressure in the mixing chamber to be 0.15MPa, raising the temperature in the mixing chamber to 400 ℃ at the speed of 10 ℃/min, preserving the temperature for 12mim, and then cooling to 200 ℃ to obtain a mixture C;
in the embodiment, the thickening agent and the compatilizer are added into the mixture B with better elasticity and adsorption performance, so that the tensile property is improved when the finally prepared tensile casting sheet is stretched, the tensile stress point is not easy to break, and the tensile uniformity is improved. Simultaneously, let in nitrogen gas in this step, the planar structure between the carbon element in mixture B can be changed in the infiltration of nitrogen element in the nitrogen gas, can make better the integration between each component to combine out the carbon nitrogen bond, make the film material that finally obtains have better ductility, then stretch out thinner bag making film.
Sixthly, putting the mixture C into an extruder to be extruded to obtain a tensile casting sheet;
and step seven, placing the stretched casting sheet in a biaxial stretching device for stretching, and obtaining the ultrathin BOPP printing bag making film after slicing, corona, printing and rolling after stretching.
Example 2
The preparation method of the ultrathin BOPP printing bag making film comprises the following steps:
step one, preparing a propylene polymer; the preparation method of the propylene polymer in this example is as follows: carrying out polymerization reaction on propylene monomers in a deionized water reaction kettle with the reaction pressure of 0.6MPa and the temperature of 3-5 ℃, and adding ammonium persulfate and ferrous sulfate in sequence in the polymerization reaction process. Wherein the mass of the ammonium persulfate is 0.5 percent of the mass of the deionized water, and the mass of the ferrous sulfate is 0.25 percent of the mass of the deionized water.
Step two, uniformly mixing the propylene polymer and polyisoprene in the step one according to the mass ratio of 8:1 to obtain a mixture A;
step three, the mixture A in the step two is processed by a casting machine to obtain mixed slurry, and the processing temperature in the casting machine is 200 ℃;
step four, adding 15% by mass of modified plant fibers into the mixed slurry, and uniformly mixing to obtain a mixture B;
wherein, the modified plant fiber is prepared by putting natural plant fiber into sodium hydroxide with the concentration of 20% for water bath treatment for 1h, the water bath treatment temperature is 60 ℃, and after treatment, centrifugal dealkalization treatment is carried out until the alkali content in the natural plant fiber is 40%; then soaking the natural plant fiber subjected to alkali treatment in a glutaraldehyde solution for 10 hours, placing the natural plant fiber after soaking in water at 180 ℃ for hydrothermal reaction for 12 hours, and cooling to obtain modified plant fiber;
step five, adding a mixture of a thickening agent and a compatilizer with the mass percent of 5-8% into the mixture B, controlling the mass ratio of the thickening agent to the compatilizer in the mixture of the thickening agent and the compatilizer to be 25:1, controlling the temperature in a mixing chamber to be 180 ℃ during mixing, mixing for 15min, introducing nitrogen into the mixing chamber, controlling the pressure in the mixing chamber to be 0.15MPa, raising the temperature in the mixing chamber to 450 ℃ at the speed of 10 ℃/min, preserving the heat for 12mim, and then cooling to 220 ℃ to obtain a mixture C;
sixthly, putting the mixture C into an extruder to be extruded to obtain a tensile casting sheet;
and step seven, placing the stretched casting sheet in a biaxial stretching device for stretching, and obtaining the ultrathin BOPP printing bag making film after slicing, corona, printing and rolling after stretching.
After the BOPP printed bag making film finally prepared in this example is subjected to the relevant performance tests, the tensile properties, elastic properties, and the like of the BOPP printed bag making film are not much different from those of example 1.
Example 3
The preparation method of the ultrathin BOPP printing bag making film comprises the following steps:
step one, preparing a propylene polymer; the preparation method of the propylene polymer in this example is as follows: carrying out polymerization reaction on propylene monomers in a deionized water reaction kettle with the reaction pressure of 0.6MPa and the temperature of 3-5 ℃, and adding ammonium persulfate and ferrous sulfate in sequence in the polymerization reaction process. Wherein the mass of the ammonium persulfate is 0.5 percent of the mass of the deionized water, the mass of the ferrous sulfate is 0.25 percent of the mass of the deionized water, and the propylene homopolymer is formed by polymerizing a propylene monomer and a comonomer through an olefin polymerization catalyst.
Step two, the propylene polymer in the step one is processed by a casting machine to obtain mixed slurry, and the processing temperature in the casting machine is 160-200 ℃;
step four, adding 10-15% of natural plant fibers in percentage by mass into the mixed slurry, and uniformly mixing to obtain a mixture B;
step five, adding a mixture of a thickening agent and a compatilizer with the mass percentage of 5-8% into the mixture B, wherein the mass ratio of the thickening agent to the compatilizer in the mixture of the thickening agent and the compatilizer is 20-25:1, the temperature in a mixing chamber is controlled to be 170-200 ℃ during mixing, the mixing time is 10-15min, then nitrogen is introduced into the mixing chamber, the pressure in the mixing chamber is controlled to be 0.15MPa, the temperature in the mixing chamber is increased to 400-450 ℃ at the speed of 10 ℃/min, the temperature is kept for 12mim, and then the temperature is reduced to 180-220 ℃ to obtain a mixture C;
sixthly, putting the mixture C into an extruder to be extruded to obtain a tensile casting sheet;
and step seven, placing the stretched casting sheet in a biaxial stretching device for stretching, and obtaining the ultrathin BOPP printing bag making film after slicing, corona, printing and rolling after stretching.
In the embodiment, common natural plant fibers are added into the mixed slurry, and polyisoprene is not added, compared with the embodiment 1 and the embodiment 2, the tensile property, the elastic property and the like of the BOPP printing bag-making film obtained finally are obviously reduced compared with the embodiment 1 and the embodiment 2.
Example 4
An ultra-thin BOPP printed bagging film made by the method of making the ultra-thin BOPP printed bagging film of example 1 or example 2.
Example 5
The ultrathin BOPP printed bagging film is prepared by the preparation method of the ultrathin BOPP printed bagging film in the embodiment 1 or the embodiment 2, and in addition, the specific structure of the biaxial stretching device in the seventh step is as follows:
as shown in fig. 1-8, the device comprises a device body 1, the device body 1 includes two oppositely arranged installation side plates 101, the device body 1 further includes an upper plate 301 and a lower plate 401 located at the upper and lower end faces of the installation side plates 101, the lower part of the lower plate 401 is further provided with a base, the base is a rectangular frame structure formed by a plurality of rods, and the base is configured to support the whole stretching device so as to be better matched with other devices in the BOPP film production process, such as an extruder in the preceding step, a cooling device in the subsequent step, a heat treatment device, a coating device, a winding device, and the like. In this embodiment can also design into the structural style that can go up and down with the base to make its better and other equipment cooperations, make whole BOPP film production technology go on more stably, efficient.
Install vertical tension mechanism on the installation curb plate 101, vertical tension mechanism is including installing the stretch roller set 102 that just the level was arranged between two installation curb plates 101, and stretch roller set 102 includes two fixed rolls 103 in this embodiment, and stretch roller set 102 is still including setting up a movable roll 104 between two adjacent fixed rolls 103, can set up with fixed roll 103 and movable roll 104 of a large amount according to the demand in the actual product, and its quantity is more, and tensile performance is better, tensile efficiency is higher.
The movable roller 104 can move up and down along the height direction of the installation side plates 101, the tension roller 105 positioned outside the tension roller group 102 is further arranged between the two installation side plates 101, and the tension roller 105 can move up and down along the height direction of the installation side plates 101. In this embodiment, a plurality of pairs of longitudinal sliding grooves 201 which are arranged oppositely are arranged on the two mounting side plates 101, a motor mounting seat 202 which can slide along the longitudinal sliding grooves 201 is arranged in each longitudinal sliding groove 201, a first driving motor 203 is mounted on each motor mounting seat 202, one end of each of the movable roller 104 and the tension roller 105 extends into each motor mounting seat 202 and is connected with a motor shaft of the corresponding first driving motor 203, and the other end of each movable roller 104 and the other end of each tension roller 105 are in clearance fit with the corresponding longitudinal sliding groove 201; a second driving motor 204 connected with one end of the fixed roller 103 is fixedly installed on the outer side surface of the installation side plate 101, and the other end of the fixed roller 103 is rotatably connected to the installation side plate 101. A mounting seat driving cylinder 302 is fixed on the upper end plate 301, a piston rod of the mounting seat driving cylinder 302 is longitudinally arranged, and the lower end part of the mounting seat driving cylinder 302 is connected with the motor mounting seat 202.
In this embodiment, the guide rollers 106 located at two end portions of the apparatus body are further disposed between two mounting side plates of the apparatus body, when a BOPP film is longitudinally stretched, two ends of the film are fixed, and the tail end of the film is rolled by the rolling mechanism, the film is horizontally fed into the stretching apparatus before stretching by the guide rollers 106, and horizontally discharged out of the stretching apparatus after stretching, in addition to the stretching of the two ends of the film by applying force, the movable rollers 104 are also moved upwards by the driving cylinders and the driving motors, and in the moving process, the movable rollers 104 and the fixed rollers 103 are both in a rotating state, and the control of the stretching uniformity of the film can be realized by adjusting the rotation speed. The movable roller 104 can drive the film to move upwards in the upward movement process, so that the movable roller 104 applies force to the film to realize longitudinal stretching of the film at the movable roller 104, if enough movable rollers 104 are available, stretching and force application at more positions can be realized, and the uniformity of the longitudinal stretching of the film can be better.
In this embodiment, a plurality of transverse stretching mechanisms 404 are arranged on the lower bottom plate 401 and between the two mounting side plates 101, the transverse stretching mechanisms 404 are arranged between the movable rollers 104 and the fixed rollers 103, each transverse stretching mechanism 404 comprises two support plates 402 connected through a transversely arranged spring, the lower end surfaces of the support plates 402 are slidably connected to the upper surface of the lower bottom plate 401, the upper surface of each support plate 402 is provided with a stretching plate 403 capable of moving transversely, and a clamping gap for clamping the BOPP film is formed between the upper surface of each support plate 402 and the lower surface of each stretching plate 403; when the movable roller 104 moves to the bottommost part, a film passing gap is formed in the horizontal direction with the fixed roller 103, and the clamping gap and the film passing gap are on the same horizontal plane and have the same width.
In this embodiment, a sliding block 405 is disposed on the lower end surface of the supporting plate 402, and a sliding groove which is transversely disposed and is matched with the sliding block 405 is disposed on the upper surface of the lower base plate 401. The upper surface of the support plate 402 includes a horizontal section 406 and an inclined section 407, the horizontal section 406 is located at the middle of the apparatus body 1, and the inclined section 407 is located at the edge of the apparatus body 1 near the installation side plate 101 and is inclined upward from the middle to the edge. A plurality of traveling rollers 408 which are axially vertical to the moving direction of the stretching plate 403 are arranged on the lower surface of the stretching plate 403, a pull rod 409 is arranged at the end part of the stretching plate 403, a limit plate 410 is arranged at the end part of the support plate 402 close to the installation side plate 101, and the pull rod 409 passes through the limit plate 410 and is connected with a stretching plate driving cylinder 411 which is arranged on the installation side plate 101 and is used for driving the stretching plate 403.
When the BOPP film is transversely stretched, the stretching plate 403 in the initial state is located at the edge of the device body 1 and abuts against the mounting side plate 101, before stretching, the movable roller 104 needs to be lowered below the fixed roller 103 to form a film passing gap with the fixed roller 103, so that the BOPP film in the stretching roller group 102 is in a horizontal state, the BOPP film is tiled on the supporting plate 402 at the moment, then the stretching plate 403 is moved to the middle of the device body 1 to clamp the BOPP film between the stretching plate 403 and the supporting plate 402, then the stretching plate 403 is moved towards the edge of the device body 1 until the stretching plate is moved to the inclined surface of the supporting plate 402 to gradually clamp the edge of the BOPP film, and the stretching plate continues to directly transversely stretch the BOPP film on the one hand, and on the other hand, the supporting plate 402 can be driven to move towards the edge of the device body 1, so that the BOPP film is transversely stretched again, and this kind of mode is because the degree that presss from both sides tight to film edge is more and more near to can make the tensile degree at film edge bigger, effectively avoid being less than the tensile inhomogeneous condition that the tensile degree leads to in the middle of the tensile degree of edge portion that leads to because of the edge portion presss from both sides tightly.
In order to ensure that the BOPP film is in a horizontal state, the tension rollers 105 need to be lifted in the descending process of the movable roller 104, so that the tension rollers 105 tension the film positioned outside the stretching roller group 102, in this embodiment, the tension rollers 105 are arranged on the front side and the rear side of the stretching roller group 102, and the distance between each tension roller 105 and the adjacent fixed roller 103 is smaller than the distance between each fixed roller 103 and the movable roller 104, so that two tension rollers 105 are configured to horizontally tension the film which is excessive when the movable roller 104 descends, so as to ensure that the BOPP film is in a horizontal state when the BOPP film is transversely stretched, and ensure the transverse stretching quality.
In this embodiment, a film limiting mechanism 501 connected to the transverse stretching mechanism 404 is disposed on the upper surface of the movable roller 104, the film limiting mechanism 501 includes an elongated slot 502 disposed on the upper surface of the movable roller 104 and extending along the axial direction of the movable roller 104, and further includes two limiting assemblies 503 arranged oppositely, each limiting assembly 503 includes a limiting block 504 inserted into the elongated slot 502 and in interference fit with the elongated slot 502, the limiting block 504 can slide along the elongated slot 502 under the action of an external force, and further includes a sliding block 505 connected to the limiting block 504 through a spring, the sliding block 505 is in clearance fit with the elongated slot 502 and the sliding block 505 is L-shaped, and the sliding blocks 505 located at two sides of the movable roller 104 together form a limiting gap for limiting two side edges of. The lower end of the limiting block 504 is provided with inserting blocks 506 at two sides of the limiting block 504, and the inserting blocks 506 can be completely inserted into the supporting plate 402 from top to bottom.
The arrangement of the film limiting mechanism 501 can ensure that the BOPP film does not deviate from the central position of the device body 1 during stretching, so as to improve the uniformity of longitudinal stretching; in addition, the film limiting mechanism 501 is connected to the transverse stretching mechanism 404, when the movable roller 104 moves below the fixed roller 103, the insertion block 506 on the limiting block 504 is inserted into the supporting plate 402, and when the stretching plate 403 drives the supporting plate 402 to move towards the edge of the device body 1, the supporting plate 402 drives the limiting block 504 to overcome the friction force between the limiting block and the elongated slot 502 and the elastic force of the spring to move towards the edge of the device body 1, so as to ensure that the sliding block 505 does not interfere with the stretched film edge; when the supporting block moves toward the middle of the apparatus body 1 under the action of the spring before the next section of film is stretched transversely, the limiting block 504 also moves to the original position toward the middle of the apparatus body 1 at this time. In addition, the limiting block 504 and the sliding block 505 in this embodiment are also connected by a spring, so that when the film is limited, if the width of the film is wide, the film can overcome the spring force to move the sliding blocks 505 on the two sides back to back, so as to ensure that the sliding blocks do not interfere with the edge of the film.
The specific stretching process comprises the following steps:
step S1, longitudinal stretching: placing the stretched casting sheet on the BOPP film multipoint stretching device for longitudinal stretching, and specifically comprising the following steps:
step S11, placing the stretch cast sheet on the tension roller 105 and the stretch roller group 102, fixing the two ends of the BOPP film, and starting a first driving motor 203 connected with the movable roller 104 and a second driving motor 204 connected with the fixed roller 103 to enable the fixed roller 103 and the movable roller 104 to be in a rotating state;
step S12, horizontally moving the movable roller 104 in the drawing roller group 102 upwards through the mounting seat driving cylinder 302 to drive the BOPP film to move upwards, and winding the tail end of the BOPP film through a winding roller in the process;
step S2, transition of longitudinal stretching and transverse stretching: after the longitudinal stretching is finished, a mounting seat driving air cylinder 302 connected with the movable roller 104 is driven to enable the movable roller 104 to move downwards until the movable roller 104 moves to the lower part of the fixed roller 103 and forms a film passing gap with the fixed roller 103, meanwhile, a first driving motor 203 connected with the tension roller 105 and the mounting seat driving air cylinder 302 used for driving the tension roller 105 to move up and down are started, and the tension roller 105 moves upwards to enable the film to be in a horizontal state;
step S3, transverse stretching: placing the stretched casting sheet on the BOPP film multipoint stretching device for transverse stretching, and specifically comprising the following steps:
step S31, the BOPP film is placed on the supporting plate 402 under the action of the tension roller 105 and the movable roller 104, and the inserting block 506 on the limiting block 504 is completely inserted into the supporting plate 402;
step S32, placing the stretching plate 403 on the upper surface of the BOPP film under the action of the stretching plate driving cylinder 411;
step S33, driving the stretching plate driving cylinder 411 to make the stretching plate 403 move towards the installation side plate 101 until the edge of the BOPP film is clamped on the inclined surface of the support plate 402;
step S34, the stretching plate 403 continues to move to the end of the supporting plate 402 and drives the supporting plate 402 to move toward the edge, and the supporting plate 402 drives the film limiting mechanism 501 to move so as to stretch the BOPP film in the transverse direction.
The method in the embodiment can ensure that the finally prepared BOPP film has better uniformity, higher film thickness and better performance.
In summary, the above-mentioned embodiments are only preferred embodiments of the present invention, and all equivalent changes and modifications made in the claims of the present invention should be covered by the claims of the present invention.

Claims (6)

1. The preparation method of the ultrathin BOPP printing bag making film is characterized by comprising the following steps:
step one, preparing a propylene polymer by using a propylene monomer;
step two, uniformly mixing the propylene polymer and polyisoprene in the step one according to the mass ratio of 6-8:1 to obtain a mixture A;
step three, the mixture A in the step two is processed by a casting machine to obtain mixed slurry, and the processing temperature in the casting machine is 160-200 ℃;
step four, adding 10-15% by mass of modified plant fibers into the mixed slurry, and uniformly mixing to obtain a mixture B; wherein, the modified plant fiber is prepared by putting natural plant fiber into 10-20% sodium hydroxide for water bath treatment for 1h, the water bath treatment temperature is 60 ℃, and after treatment, centrifugal dealkalization treatment is carried out until the alkali content in the natural plant fiber is 30-40%; then soaking the natural plant fiber subjected to alkali treatment in a glutaraldehyde solution for 10h, placing the soaked natural plant fiber in water with the temperature of 150-180 ℃ for hydrothermal reaction, and cooling to obtain modified plant fiber;
step five, adding a mixture of 5-8% by mass of a thickening agent and a compatilizer into the mixture B, controlling the temperature in the mixing chamber to be 170-200 ℃ during mixing, and the mixing time to be 10-15min, then introducing nitrogen into the mixing chamber, controlling the pressure in the mixing chamber to be 0.15MPa, raising the temperature in the mixing chamber to be 400-450 ℃ at the speed of 10 ℃/min, preserving the heat for 12mim, and then cooling to 180-220 ℃ to obtain a mixture C;
sixthly, putting the mixture C into an extruder to be extruded to obtain a tensile casting sheet;
and step seven, placing the stretched casting sheet in a biaxial stretching device for stretching, and obtaining the ultrathin BOPP printing bag making film after slicing, corona, printing and rolling after stretching.
2. The method of preparing an ultra-thin BOPP printed bagging film of claim 1, wherein: the preparation method of the propylene polymer in the first step comprises the following steps: carrying out polymerization reaction on propylene monomers in a deionized water reaction kettle with the reaction pressure of 0.6MPa and the temperature of 3-5 ℃, and adding ammonium persulfate and ferrous sulfate in sequence in the polymerization reaction process.
3. The method of preparing an ultra-thin BOPP printed bagging film of claim 2, wherein: the mass of the ammonium persulfate is 0.5 percent of the mass of the deionized water, and the mass of the ferrous sulfate is 0.25 percent of the mass of the deionized water.
4. The method of preparing an ultra-thin BOPP printed bagging film of claim 1, wherein: the hydrothermal reaction time in the fourth step is 10-14 h.
5. The method of preparing an ultra-thin BOPP printed bagging film of claim 1, wherein: and in the fifth step, the mass ratio of the thickening agent to the compatilizer in the mixture of the thickening agent and the compatilizer is 20-25: 1.
6. Ultra-thin BOPP printing system bag membrane, its characterized in that: which is prepared by the method for preparing the ultra-thin BOPP printed bagging film according to any one of claims 1 to 5.
CN202110448236.1A 2021-04-25 2021-04-25 Ultrathin BOPP printing bag making film and preparation method thereof Pending CN113024863A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020173602A1 (en) * 1998-03-26 2002-11-21 David Appleyard Random propylene copolymers
CN102190824A (en) * 2010-03-15 2011-09-21 江苏彩华包装集团公司 Hot-seal functional stretch film
CN103434151A (en) * 2013-08-30 2013-12-11 华威聚酰亚胺有限责任公司 High-performance ultrathin polypropylene capacitor film and manufacturing method thereof
US20160304681A1 (en) * 2013-12-18 2016-10-20 Borealis Ag Bopp film with improved stiffness/toughness balance

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020173602A1 (en) * 1998-03-26 2002-11-21 David Appleyard Random propylene copolymers
CN102190824A (en) * 2010-03-15 2011-09-21 江苏彩华包装集团公司 Hot-seal functional stretch film
CN103434151A (en) * 2013-08-30 2013-12-11 华威聚酰亚胺有限责任公司 High-performance ultrathin polypropylene capacitor film and manufacturing method thereof
US20160304681A1 (en) * 2013-12-18 2016-10-20 Borealis Ag Bopp film with improved stiffness/toughness balance

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Application publication date: 20210625