CN111546733B - PE blown film, PE composite film, packaging bag and preparation method of packaging bag - Google Patents

Abstract

The invention relates to the technical field of sealing packaging materials, in particular to a PE (polyethylene) blown film, a PE composite film prepared from the PE blown film, a double-volume intercommunicated flexible packaging bag prepared from the PE composite film and a preparation method of the packaging bag. The intercommunicated flexible packaging bag comprises a packaging bag main body and a destructible partition part, wherein the packaging bag main body is made of a PE composite film, and the destructible partition part is made of an opposite packaging main body with a PE strip clamped in the middle; PB and PE are incompatible two phases, but have good mutual dispersibility under the action of heating melting and shearing stress, so that PB and PE can be well melted and sealed with a PE composite film after being blended into a film, namely a PE strip, and the incompatible phases of PB and PE in the PE strip are completely separated under the action of stripping force, have slight stripping deformation but not obvious tensile deformation, so that clean separation can be realized. The sealing performance of the destructible separating part is excellent, the heat sealing strength is controllable and stable, and the bag making operation is simple.

Description

PE blown film, PE composite film, packaging bag and preparation method of packaging bag

Technical Field

The invention relates to the technical field of sealing packaging materials, in particular to a PE (polyethylene) blown film, a PE composite film prepared from the PE blown film, a double-volume intercommunicated flexible packaging bag prepared from the PE composite film and a preparation method of the packaging bag.

Background

There are some mix products with different moisture content, such as solid-liquid mix products, dried fruits, nuts, etc. with different moisture content. In order to prolong the shelf life of the mixed product or keep the original flavor of the mixed product, the traditional package adopts a mode of mixing and packaging with a drying agent or a mode of independent packaging; the mode of mixing, packaging and adding the drying agent is easy to cause the water loss of the content of the wet component, and the content of the dry component absorbs water, so that the mixture is easy to go bad and mildew, and the storage life is reduced; the contents are separately packaged independently, so that the contents are guaranteed not to influence each other, but the problems of inconvenience in consumption and failure in mixing operation of consumers exist, the waste of packaging materials is brought, the cost of a packaging process is increased, and the use convenience of the consumers is influenced.

In order to solve the problems of the packaging mode, a double-cavity integrated packaging mode appears on the market, wherein one packaging bag has two or more volumes, a plurality of volumes are separately packaged in a separated mode during packaging, transportation and sale, and when the packaging bag is consumed and used, the packaging bag does not need to be opened, only the separated area needs to be cleanly uncovered, the volumes are communicated, and the contents can be communicated and mixed. At present, the double-cavity integral packaging mode technology is to use a virtual seal (reduce the heat sealing temperature of a heat sealing hot strip of a separation region and reduce the heat sealing pressure) to bond a middle separation region during bag making, but the bonding can be reduced along with the movement of a high molecular chain along with the time, and particularly, when the environmental temperature is increased, the separation region of the virtual seal can be automatically separated; the control of the bag making operation of the virtual seal is very difficult, and especially when the thickness of the composite film material is uneven, the virtual seal is insufficient (the composite film is thin), namely, the contents are communicated when being filled, or the virtual seal is too large (the composite film is thick), namely, the end consumer hardly uncovers the separation area to ensure that the two volumes are not communicated.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects in the prior art and provide a PE blown film;

another technical problem to be solved by the present invention is to provide a PE composite film prepared by blowing a PE film;

another technical problem to be solved by the present invention is to provide a flexible packaging bag with double volumes and intercommunicating prepared from a PE composite film;

the invention aims to solve the technical problem of providing a preparation method of a double-volume intercommunicated flexible packaging bag prepared from a PE composite film;

in order to solve the technical problem, the invention adopts the technical scheme that the PE blown film is prepared by a three-layer coextrusion molding mode through a first composite layer, a first core layer and a first heat sealing layer, wherein the first composite layer is composed of linear low-density polyethylene resin with the mark of 1002YB produced by Exxon and low-density polyethylene resin with the mark of 150BW produced by Exxon according to the proportion of (1-3) to (3-1); the first core layer is composed of metallocene linear low-density polyethylene resin with the Dow brand of 5100G, linear low-density polyethylene resin with the Dow brand of 2045G and low-density polyethylene resin with the Exxon brand of 150BW according to the proportion of 1:1 (1-2); the first heat-sealing layer is composed of Dow 5100G metallocene linear low-density polyethylene resin, 2045G linear low-density polyethylene resin produced by Dow, and 150BW low-density polyethylene resin produced by Exxon according to the proportion of (1-2) to 1: 1.

In order to solve another technical problem, the invention adopts the technical scheme that the PE composite film is formed by sequentially overlapping a printing film, an ink layer, an adhesive layer and a PE blown film; or the PE composite film is formed by sequentially overlapping a printing film, an ink layer, an adhesive layer, an intermediate layer and a PE blown film.

As a further improvement of the PE composite film:

preferably, the printing film is selected from one of BOPP, BOPET, BOPA and paper.

Preferably, the intermediate layer is of a single-layer or multi-layer structure, and each layer is any one of PET, VMPET, paper, aluminum foil and BOPA.

In order to solve still another technical problem, the present invention adopts the technical scheme that a double-volume intercommunicated flexible packaging bag made of a PE composite film comprises a packaging bag main body and a breakable partition part, wherein the breakable partition part divides an inner cavity of the packaging bag main body into two chambers, the two chambers are communicated after the breakable partition part is broken, the packaging bag main body is made of a PE composite film, and a PE strip is sandwiched between the packaging bag main body and the breakable partition part.

As a further improvement of the above dual volume intercommunicating flexible package:

preferably, the PE strip is prepared by a three-layer co-extrusion molding mode through a second heat sealing layer, a second core layer and a third heat sealing layer, the second heat sealing layer is composed of metallocene linear low-density polyethylene resin, linear low-density polyethylene resin and low-density polyethylene resin in a mass ratio of 1:1:1-2:1:1, the second core layer is composed of linear low-density polyethylene resin and low-density polyethylene resin in a mass ratio of 1:3-3:1, and the third heat sealing layer is composed of metallocene linear low-density polyethylene resin, linear low-density polyethylene resin and polybutylene resin in a mass ratio of 1:2:1-3:1: 1.

More preferably, the PE tape has a metallocene linear low density polyethylene resin brand of dow 5100G, a linear low density polyethylene resin brand of dow 2045G, and a low density polyethylene resin brand of eksen 150 BW; the linear low-density polyethylene resin of the second core layer is 2045G Dow, and the low-density polyethylene resin of the second core layer is 150BW Exxon; the metallocene linear low-density polyethylene resin of the third heat-sealing layer is Dow 5100G, the linear low-density polyethylene resin of the third heat-sealing layer is Exxon 1002YB, and the polybutylene resin of the third heat-sealing layer is Bassel 8640M.

In order to solve another technical problem, the invention adopts the technical scheme that the preparation method of the double-volume intercommunicated flexible packaging bag comprises the following steps:

s1, weighing the components in parts by weight respectively according to the formula composition of a first composite layer, a first core layer and a first heat sealing layer in the PE blown film, and then preparing the PE blown film by adopting a three-layer co-extrusion film blowing process;

s2, weighing the components in parts by weight respectively according to the formula composition of a second heat-sealing layer, a second core layer and a third heat-sealing layer in the PE strip, and then preparing the PE strip by adopting a three-layer co-extrusion film blowing process;

s3, printing the benzene-free ink on the printing film in a gravure printing mode at the printing speed of 120-150m/min, and drying and curing the ink at the temperature of 65-80 ℃ to form an ink layer;

adopting a dry-type compounding or solvent-free compounding gluing mode, and uniformly coating the composite glue on one side of the printing ink layer, which is far away from the printing film, by using a gluing roller to form an adhesive layer;

if the composite film contains the middle layer, the middle layer is adhered to the side, away from the ink layer, of the adhesive;

s4, heating and pressing the PE blown film prepared in the step S1 and the printing film prepared in the step S3 through a laminating roller at the temperature of 70-90 ℃ and under the pressure of 0.2-0.4MPa, wherein the PE blown film is connected with an adhesive layer or an intermediate layer, and a PE composite film is prepared;

s5, adding an unreeling device for unreeling the PE strips of the winding drum on bag making equipment, putting the PE strips between two PE composite films when the PE composite films are cut into an upper piece and a lower piece on the bag making machine, wherein the PE strips are connected with PE blown films of the PE composite films according to set positions, and performing edge sealing and heat sealing on PE strip areas on the peripheries of the two PE composite films at 140-200 ℃ to complete bag making sealing and sealing of the PE strips;

wherein, the steps S1, S2 and S3 are not in sequence.

Compared with the prior art, the invention has the beneficial effects that:

1) in the technical scheme of the invention, the PE blown film is prepared by a first composite layer, a first core layer and a first heat sealing layer in a three-layer co-extrusion mode, wherein the composite layer of the first composite layer has better corona treatment performance, and the formula particles do not contain auxiliaries such as openings, smoothness and the like; the first middle layer has better processability, the proportion of LDPE with good processability is higher, and 25% of metallocene PE is added, so that the melting and rewinding degree of the heat-sealing layer during heat sealing can be facilitated, and the heat-sealing strength is improved; the first heat sealing layer mainly uses metallocene particles with a high proportion, and LDPE for improving processability and LLDPE for improving mechanical strength are added;

in the technical scheme of the invention, the PE strip is prepared by a second heat sealing layer, a second core layer and a third heat sealing layer in a three-layer co-extrusion mode, wherein the second heat sealing layer has the same formula as the first heat sealing layer of the PE blown film and is fused with the PE composite film after heat sealing, wound and sealed completely; polybutylene particles are added into the third heat-sealing layer, can be subjected to heat-sealing, melting and winding with the PE composite film, and can be completely peeled off at the interface of different phases of polybutylene and PE blown film;

the PE composite film is formed by sequentially overlapping a printing film, an ink layer, an adhesive layer and a PE blown film, or formed by sequentially overlapping the printing film, the ink layer, the adhesive layer, a middle layer and the PE blown film.

2) In the prior art, when preparing intercommunicated flexible packaging bags, virtual seal bonding is adopted, concave-convex deformation is formed by utilizing a high polymer material under the action of certain temperature and pressure to produce mechanical tooth force, and high polymer resin on a shallow surface layer is wound to form bonding strength; the adhesive strength gradually decreases along with the increase of storage time, the rise of ambient temperature and the self-movement of the polymer chains, so that the separation of the virtual sealed isolation regions is caused; meanwhile, when bags are made, the virtual seal is insufficient or excessive due to uneven thickness of the composite film material, so that the filling volumes are communicated or are difficult to separate.

The intercommunicated flexible packaging bag comprises a packaging bag main body and a destructible partition part, wherein the packaging bag main body is made of a PE composite film, a PE strip is clamped between the packaging bag main bodies of the destructible partition part, and a PE film blowing in the PE composite film is connected with the PE strip; PB and PE are incompatible two phases, but have good mutual dispersibility under the action of heating melting and shearing stress, so PB and PE can be well melted and sealed with a PE composite film after being blended into a film, namely a PE strip, because PE in the PE strip of the blended film and PE in the PE composite film can be completely compatible and mutually wound, and a separation area of a packaging bag is not easy to automatically separate; under the action of peeling force, PB in the PE strip and incompatible phases of PE are completely separated, and the PB and the PE strip have slight peeling deformation but no obvious tensile deformation, so that clean separation can be realized.

3) The heat seal strength of the separating part in the flexible packaging bag capable of intercommunicating is finally expressed as the separating strength of different phases, and is related to the quantity ratio of the two phases (namely PB content sum), when the PB content is increased, the heat seal strength has small influence on the heat seal peeling force because the different phases are dispersed and distributed greatly, almost no in-phase separation exists, and the tested peeling force comes from the out-of-phase separating strength, so that the heat seal strength tends to be stable and is not influenced by the heat seal cover area. The heat-sealing strength of the partition part can be realized by adjusting the heat-sealing width, the preset strength is not influenced by the change of the thickness uniformity of the composite film, the bag making controllable range is wide, and the operation is easy; the bag-making equipment is simple to reform and can be used by adding a PE strip unwinding device.

4) The intercommunicated soft packaging bag does not require the heat sealing areas of the intercommunicated edges to have high sealing strength, so that the contents can be well protected; the heat-sealed area of the partition is controllable sealing strength with excellent sealing performance, and sealing and peeling force can be designed according to end customer groups, sales areas, transportation conditions and the like; the common bag sealing device can be used only by additionally arranging a PE strip unreeling device, and the bag making operation is simple; the heat sealing process of the destructive separating part prepared from the PE strip and the PE composite film is wide in operation range, the heat sealing strength is stable, and the size and the stability of the heat sealing strength can be controlled by adjusting the formula of the PE strip and combining the heat sealing width.

Drawings

FIG. 1 is a schematic diagram of two structural structures of a PE composite membrane;

FIG. 2 is a flow chart of a process for producing a PE composite membrane;

FIG. 3 is the destructive divider heat seal strength of interoperable flexible packages prepared from PE tapes of different heat seal widths with a PB content of 50% in the heat seal layer of the PE tapes;

FIG. 4 is the destructive divider heat seal strength of interoperable flexible packages prepared from PE tapes of different heat seal widths with a PB content of 75% in the heat seal layer of the PE tapes;

FIG. 5 is a schematic diagram of the construction of a dual volume intercommunicating flexible package prepared;

the designations in the drawings have the following meanings:

1. printing a film; 2. an ink layer; 3. an adhesive layer; 4. blowing a PE film; 5. an intermediate layer; 6. an edge sealing area; 7. a breakable partition; 8. a first chamber; 9. a second chamber; 10. hanging holes on the bags;

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

Comparative example 1

S1, preparing a common PE composite membrane; the common PE composite film is formed by sequentially superposing an outer layer, a middle layer and an inner layer, wherein the outer layer is made of PET, the middle layer is VMPET, and the inner layer is prepared by co-extruding more than 80% of medium-density PE and less than 20% of low-melting-point metallocene PE;

s2, preparing a common intercommunicating flexible packaging bag; cutting the common PE composite film prepared in the step S1 into an upper piece and a lower piece, adding a long heating and ironing strip at the partition position of the double-volume intercommunicated flexible packaging bag required by a customer, performing edge sealing on the peripheries of the two common PE composite films at the temperature of 100-120 ℃ and under the pressure of 150-180kPa, and performing heat sealing on the long heating and ironing strip parts to complete bag making sealing and sealing of the partition part, thereby preparing the common intercommunicated flexible packaging bag.

Example 1

S1, weighing the components in parts by weight respectively according to the formula composition of a first composite layer, a first core layer and a first heat sealing layer in the PE blown film shown in the following table 2, and then preparing a film by adopting a three-layer co-extrusion blown film process to obtain a PE blown film 1;

weighing the components in parts by weight according to the formula composition of a second heat-sealing layer, a second core layer and a third heat-sealing layer in the PE strip shown in the following table 2, and preparing a film by adopting a three-layer co-extrusion film blowing process to obtain a PE strip 1;

weighing the components in parts by weight according to the formula composition of a second heat-sealing layer, a second core layer and a third heat-sealing layer in the PE strip shown in the following table 2, and preparing a film by adopting a three-layer co-extrusion film blowing process to obtain a PE strip 2;

the properties of each particle used in the above preparation process are shown in table 1 below:

TABLE 1 Properties of different particles

TABLE 2 composition ratio of PE blown film 1, PE strip 1 and PE strip 2

S2, printing the benzene-free ink on the printing film in a gravure printing mode at the printing speed of 120-150m/min, and drying and curing the ink at the temperature of 65-80 ℃ to form an ink layer;

uniformly coating the composite glue on the ink layer of the printing film by using a gluing roller in a dry-type composite or solvent-free composite gluing mode to form an adhesive layer, so as to obtain the printing film 1 coated with the printing ink and the glue;

and S3, heating and pressing the PE film by a laminating roller at the temperature of 70-90 ℃ and the pressure of 0.2-0.4MPa, and compounding the PE film 1 and the printing film 1 together, wherein the PE film is connected with the adhesive layer to obtain the PE composite film 1.

Example 2

Reforming bag-making equipment, adding an unwinding device of a PE strip between an upper film and a lower film, and preparing a double-volume intercommunicated flexible packaging bag by using the prepared PE composite film 1 and the prepared PE strip 1; when the PE composite film is cut into an upper piece and a lower piece on a bag making machine, the PE strips with the widths, namely the heat sealing lengths of 1mm, 2mm, 3mm, 4mm, 5mm and 6mm of the heat sealing PE strip 1 are placed between the two PE composite films 1, the heat sealing temperature is 135 ℃, the heat sealing time is 0.5s, and the heat sealing pressure is 180KPa, the periphery of the two PE composite films 1 and the area of the PE strip 1 are subjected to heat sealing, and the intercommunicated flexible packaging bags 1-6 of the separation areas with different transverse heat sealing lengths are prepared when the PB content in the heat sealing layer of the PE strips is 50 percent;

the heat-seal strengths of the partitioned area packages of different transverse heat-seal lengths prepared in example 2 above were measured to obtain the graph of FIG. 3.

It can be seen from the graph of fig. 3 that the heat-seal peel strength increases with increasing heat-seal length (i.e., width of the heat-seal PE strip, parallel to the force of heat-seal peel) because as the heat-seal area increases, the probability of interfusion and entanglement between the two layers increases, which is manifested by an increase in peel force. However, the magnitude of the increase is small because the main factors determining the peel strength are the PB content and the degree of dispersion, and the PB content is high, the dispersibility is good, and the peel force is low.

Example 3

Reforming bag-making equipment, adding an unwinding device of a PE strip between an upper film and a lower film, and preparing a double-volume intercommunicated flexible packaging bag by using the prepared PE composite film 1 and the prepared PE strip 2; when the PE composite film is cut into an upper piece and a lower piece on a bag making machine, the PE strips with the widths, namely the heat sealing lengths of 4mm, 6mm, 8mm, 10mm, 12mm and 14mm of the heat sealing PE strip 2 are placed between the two PE composite films 1, the heat sealing temperature is 135 ℃, the heat sealing time is 0.5s, and the heat sealing pressure is 180KPa, the periphery of the two PE composite films 1 and the area of the PE strip 2 are subjected to heat sealing, and the intercommunicated soft packaging bags 7-12 of the separation areas with different transverse heat sealing lengths are prepared when the PB content in the heat sealing layer of the PE strips is 75%;

the heat-seal strengths of the partitioned area packages of different transverse heat-seal lengths prepared in example 3 above were measured to obtain the graph of FIG. 4.

As can be seen from the graph of fig. 4, when the PB content in the heat-seal layer of the PE bar reaches 75%, the increase in the heat-seal length (i.e., the width of the heat-seal PE bar, parallel to the heat-seal peeling force) has less influence on the heat-seal peeling force because as the PB content in the heat-seal layer of the PE bar increases, the dispersion distribution between different phases is small, the separation in the same phase is small, the peeling force of the partitioning portion comes from the separation between the phases, the strength tends to be stable, and the influence by the heat-seal area is small.

The ordinary intercommunicating flexible package bags prepared in comparative example 1 and the intercommunicating flexible package bags 1 prepared in example 2 were left at room temperature for 15, 30, and 60 days, respectively, and the heat seal strengths of the package bags were measured, and the results are shown in table 3 below:

TABLE 3 Heat seal Strength of Normal intercommunicating Flexible packaging bag and intercommunicating Flexible packaging bag 1 after storage at Normal temperature

The ordinary intercommunicating flexible package bag prepared in comparative example 1 and the intercommunicating flexible package bag 1 prepared in example 2 were left at oven temperatures of 30 c, 40 c and 50 c for 10 days, respectively, and the heat seal strength of the package bags was measured, and the results are shown in table 4 below:

TABLE 4 Heat seal Strength of Normal intercommunicating Flexible packaging bags and intercommunicating Flexible packaging bag 1

The heat seal strength values in tables 3 and 4 above demonstrate that the intercommunicated flexible packaging bags prepared by the present invention have good stability of heat seal strength, and do not have large fluctuation due to the influence of environment; the heat sealing strength of the common intercommunicating flexible packaging bag prepared by the common method is reduced by the improvement of the environmental temperature and the placing time, the intercommunicating risk is generated in the isolation area under the goods shelf placing condition, and the initial isolation design requirement cannot be met.

It should be understood by those skilled in the art that the foregoing is only illustrative of several embodiments of the invention, and not of all embodiments. It should be noted that many variations and modifications are possible to those skilled in the art, and all variations and modifications that do not depart from the gist of the invention are intended to be within the scope of the invention as defined in the appended claims.

Claims (5)

1. A double-volume intercommunicated flexible packaging bag comprises a packaging bag main body and a destructible partition part, wherein the destructible partition part divides an inner cavity of the packaging bag main body into two chambers, and the two chambers are communicated after the destructible partition part is destroyed;

the PE strip is prepared by a second heat sealing layer, a second core layer and a third heat sealing layer through three-layer co-extrusion molding, the second heat sealing layer is composed of metallocene linear low-density polyethylene resin, linear low-density polyethylene resin and low-density polyethylene resin in a mass ratio of 1:1:1-2:1:1, the second core layer is composed of linear low-density polyethylene resin and low-density polyethylene resin in a mass ratio of 1:3-3:1, and the third heat sealing layer is composed of metallocene linear low-density polyethylene resin, linear low-density polyethylene resin and polybutylene resin in a mass ratio of 1:2:1-3:1: 1;

the PE composite film is formed by sequentially overlapping a printing film, an ink layer, an adhesive layer and a PE blown film; or the PE composite film is formed by sequentially overlapping a printing film, an ink layer, an adhesive layer, an intermediate layer and a PE blown film;

the PE blown film is prepared by a first composite layer, a first core layer and a first heat sealing layer through three-layer coextrusion molding, wherein the first composite layer is composed of linear low-density polyethylene resin with the mark of 1002YB produced by Exxon and low-density polyethylene resin with the mark of 150BW produced by Exxon according to the proportion of (1-3) to (3-1); the first core layer is composed of metallocene linear low-density polyethylene resin with the Dow brand of 5100G, linear low-density polyethylene resin with the Dow brand of 2045G and low-density polyethylene resin with the Exxon brand of 150BW according to the proportion of 1:1 (1-2); the first heat-sealing layer is composed of Dow 5100G metallocene linear low-density polyethylene resin, 2045G linear low-density polyethylene resin produced by Dow, and 150BW low-density polyethylene resin produced by Exxon according to the proportion of (1-2) to 1: 1.

2. The dual volume intercommunicating flexible packaging bag of claim 1, wherein the printed film is selected from one of BOPP, BOPET, BOPA, paper.

3. The dual volume intercommunicating flexible packaging bag of claim 1, wherein said intermediate layer is a single layer or a multi-layer structure, each layer being any one of PET, VMPET, paper, aluminum foil, BOPA.

4. The dual volume, intercommunicating, flexible packaging bag of claim 1, wherein said second heat seal layer has a metallocene linear low density polyethylene resin designation of dow 5100G, a second heat seal layer has a linear low density polyethylene resin designation of dow 2045G, a second heat seal layer has a low density polyethylene resin designation of eckson 150 BW; the linear low-density polyethylene resin of the second core layer is 2045G Dow, and the low-density polyethylene resin of the second core layer is 150BW Exxon; the metallocene linear low-density polyethylene resin of the third heat-sealing layer is Dow 5100G, the linear low-density polyethylene resin of the third heat-sealing layer is Exxon 1002YB, and the polybutylene resin of the third heat-sealing layer is Bassel 8640M.

5. A method of making a dual volume intercommunicating flexible packaging bag according to any of claims 1 to 4, comprising the steps of:

s1, weighing the components in parts by weight respectively according to the formula composition of a first composite layer, a first core layer and a first heat sealing layer in the PE blown film, and then preparing the PE blown film by adopting a three-layer co-extrusion film blowing process;

s2, weighing the components in parts by weight respectively according to the formula composition of a second heat-sealing layer, a second core layer and a third heat-sealing layer in the PE strip, and then preparing the PE strip by adopting a three-layer co-extrusion film blowing process;

s3, printing the benzene-free ink on the printing film in a gravure printing mode at the printing speed of 120-150m/min, and drying and curing the ink at the temperature of 65-80 ℃ to form an ink layer;

adopting a dry-type compounding or solvent-free compounding gluing mode, and uniformly coating the composite glue on one side of the printing ink layer, which is far away from the printing film, by using a gluing roller to form an adhesive layer;

if the composite film contains the middle layer, the middle layer is adhered to the side, away from the ink layer, of the adhesive;

s4, heating and pressing the PE blown film prepared in the step S1 and the printing film prepared in the step S3 through a laminating roller at the temperature of 70-90 ℃ and under the pressure of 0.2-0.4MPa, wherein the PE blown film is connected with an adhesive layer or an intermediate layer, and a PE composite film is prepared;

s5, adding an unreeling device for unreeling the PE strips of the winding drum on bag making equipment, putting the PE strips between two PE composite films when the PE composite films are cut into an upper piece and a lower piece on the bag making machine, wherein the PE strips are connected with PE blown films of the PE composite films according to set positions, and performing edge sealing and heat sealing on PE strip areas on the peripheries of the two PE composite films at 140-200 ℃ to complete bag making sealing and sealing of the PE strips;

wherein, the steps S1, S2 and S3 are not in sequence.

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