CN109648899B

CN109648899B - Special film for packing polyethylene flour bags

Info

Publication number: CN109648899B
Application number: CN201910053993.1A
Authority: CN
Inventors: 孙美菊; 李永勃; 孙爱亲; 孙东伟; 李广; 王耀正; 王勇
Original assignee: Henan Yinfeng Plastic Co ltd
Current assignee: Henan Yinfeng Plastic Co ltd
Priority date: 2019-01-21
Filing date: 2019-01-21
Publication date: 2020-12-15
Anticipated expiration: 2039-01-21
Also published as: CN109648899A

Abstract

The invention discloses a special film for packaging a polyethylene flour bag, belonging to the field of packaging films. The invention adds American imported metallocene in the outer layer, adds Japanese imported metallocene B and A in the middle layer and the inner layer, the formulas of the outer layer, the middle layer and the inner layer are different, the formulas of the outer layer, the middle layer and the inner layer are respectively mixed uniformly, and three layers of thin films are formed by a co-extrusion die head for extrusion, thus preparing the special film for packaging the polyethylene flour bag. The sealing performance is better, the cost is better, the preparation process is simpler, the heat sealing temperature is lower, the firmness is better, and the packaging method is very suitable for small-batch packaging.

Description

Special film for packing polyethylene flour bags

Technical Field

The invention relates to a special film for packaging a polyethylene flour bag, which relates to a special film for packaging a polyethylene flour bag prepared by taking a raw material of high-grade imported olefin and other auxiliary agents as raw materials, and belongs to the field of packaging films.

Background

With the improvement of living standard of people, the fine requirements of people on living are better, the prior flour package is generally a woven bag package, the weight of each bag is 15-25kg, and some families need to eat one bag for several months or even one year. Meanwhile, the flour packaged by the woven bags is easy to damp and not beneficial to flour storage, and a large amount of flour dust is inevitable in the transportation and storage processes of the flour packaged by the woven bags, so that certain potential safety hazards are caused. Thus, there is a trend towards smaller packages of flour that are stored for longer periods of time.

CN201610578977.0 reports that a plastic woven bag made of BOPP as a main material meets the hygienic requirements of flour for moisture resistance, moth prevention, pollution prevention and the like, but the storage time of the woven bag cannot be too long due to the performance of the woven bag. CN201410011003.5 describes a flour packaging film which is formed by coating a PE film with modified polypropylene and then bonding the PE film with polyurethane in an intermediate layer, the flour packaging film solves the problems of flour antistatic and heat sealing, but the modified polypropylene emulsion needs to be prepared first and then compounded and coated, the production process is complex, the cost is increased, and the popularization is difficult during industrial use.

Disclosure of Invention

Aiming at the current technical situation, the invention aims to provide the special polyethylene flour bag packaging film which is good in film transparency, high in strength, firm in heat sealing and simple in forming method, is suitable for small-batch packaging of 2-5kg, is longer in storage time and is safer to transport.

In order to realize the purpose of the invention, American imported metallocene is added into the outer layer, Japanese imported metallocene A and Japanese imported metallocene B are added into the middle layer and the inner layer, the formulas of the outer layer, the middle layer and the inner layer are different, the formulas of the outer layer, the middle layer and the inner layer are respectively and uniformly mixed, and three layers of thin films are formed by a co-extrusion die head for extrusion, so that the special film for packaging the polyethylene flour bag is prepared.

The raw material formula is that the components are calculated by weight percentage,

inner layer:

domestic linear polyethylene material a: 50-70%, Japanese imported metallocene wire type material A: 20-30%, American imported low-density polyethylene material 5-15%, opening slipping agent: 1-3%, antistatic agent: 2-5% of PPA master batch and 1-10% of PPA master batch.

Middle layer:

japanese imported metallocene wire type B: 25-45%, American imported low-density polyethylene material 15-35%, domestic linear polyethylene material A: 30-50% of PPA master batch and 1-10% of PPA master batch.

Outer layer:

domestic linear polyethylene material B: 35-55%, 30-50% of American imported metallocene wire material, 5-25% of American imported low-density polyethylene material and 1-10% of PPA master batch.

The outer layer, the middle layer and the inner layer are respectively and uniformly mixed, and are extruded to form a three-layer thin film through a die head by each layer of extruder to prepare the three-layer co-extrusion ultra-low temperature heat-sealing packaging film.

The domestic linear polyethylene material B is Daqing petrochemical 7042, the Japanese imported metallocene linear material A is Japanese KF360T, the Japanese imported metallocene linear material B is Japanese SP150H, the American imported low-density polyethylene material is Exxon Mobil 150BW, the domestic linear polyethylene A is Lanzhou petrochemical 7042, and the American imported metallocene linear material is 2018MB of the Exxon Mobil.

The following formulation is preferred: the weight percentage of each component is calculated,

inner layer:

domestic linear polyethylene material a: 51%, Japanese imported metallocene wire type material A: 25%, American imported low-density polyethylene material 15%, opening slipping agent: 2%, antistatic agent: 4% and 3% of PPA master batch.

Middle layer:

japanese imported metallocene wire type B: 35%, U.S. imported low density polyethylene material 25%, domestic linear polyethylene material a: 38 percent and PPA master batch 2 percent.

Outer layer:

domestic linear polyethylene material B: 44%, 36% of American inlet metallocene wire material, 18% of American inlet low-density polyethylene material and 2% of PPA master batch.

The technical scheme is as follows:

the outer layer, the middle layer and the inner layer are metered and then are respectively and uniformly mixed, added into a hopper, fed into an extruder, melted and extruded by a multilayer co-extruder, fed into an annular co-extrusion die head to form three-layer film extrusion, and compressed air is blown in from a cooling air pipe at the center of the die head to blow and expand the film into a cylindrical film. Cooling by internal and external air, then feeding the film into a herringbone clamping plate to exhaust air in the special film bubble for packaging the polyethylene flour bag, then performing corona treatment on an inner layer corona machine, trimming and finishing the edges of the film by a trimming machine, then rolling by a back-to-back rolling machine, and finally packaging and warehousing after detection.

In the process of preparing the special film for packing the polyethylene flour bags, the raw material formula, the melt temperature, the blowing ratio, the traction ratio and the condensation line height all influence the film performance, and the optimum processing parameters are obtained by combining the optimized processing process conditions and comparing: the melting temperature is 175-190 ℃; blow-up ratio of film 1.5: 2.5; draw ratio of film 1: 8-15, the corona power is 2-4 KVA, and the corona on the surface of the film is 40-44 dynes.

The principle of the invention is as follows: the special film for packaging the polyethylene flour bag is produced by adopting a three-layer co-extrusion process, the inner layer is an antistatic and heat-sealing layer, and the small flour particles are adsorbed on the surface of the film, so that the heat-sealing of the film is not firm, the adsorption quantity of the film surface is reduced by the antistatic agent on the inner layer, and meanwhile, the heat-sealing temperature is reduced by means of the Japanese metallocene A, so that the resin can surround the small flour particles, and the heat-sealing strength is improved; the middle layer is a heat-sealing transition layer and an enhancement layer, and in order to reduce the cost, Japanese imported metallocene B is selected to improve the strength and the heat-sealing transition; the outer layer is a corona printing layer, American imported metallocene is adopted to improve the strength, and meanwhile, the printing is easier to perform at the later stage because the opening slipping agent is not contained.

The invention has the advantages that: because the strength of the metallocene imported from America is higher, and the strength of the metallocene imported from middle-layer Japan is added, the tensile strength can reach more than 41MPa, the tensile strain at break can reach more than 920 percent, and meanwhile, the puncture resistance is excellent; japanese Advance metallocenes A and B and an antistatic agent were added to the inner and middle layers, respectively, so that the heat-sealing was very firm at a heat-sealing temperature of 120 ℃ and 5kg of the sample packaging bag was not broken when it was dropped from the third floor. Is very convenient for transportation and storage.

At present, each index is detected by referring to the standard of a polyethylene blown film for packaging GB4456-2008, and through the inspection and test of an authoritative department, each quality technical index reaches or exceeds the national standard (GB4456-2008), wherein part of the indexes are more than 2 times better than the national standard (GB 4456-2008).

The invention relates to a special three-layer co-extruded polyethylene flour bag packaging film andcompared with other flour packages, the materials are selected from polyethylene which is easy to blow mould and process as the main raw material, and the Japanese imported metallocene A is matched with the antistatic agent, so that the heat sealing effect is very ideal, and meanwhile, the density of the Japanese imported metallocene is 0.925g/cm higher than that of the common metallocene³Lower, only 0.898g/cm³Therefore, the softness is better, and the cold resistance and freezing resistance are better. Has good application prospect.

Detailed Description

For a better illustration of the present invention, the following examples are given, all starting materials being commercially available.

Example 1

Inner layer:

Middle layer:

Outer layer:

According to the formula, the outer layer formula, the middle layer formula and the inner layer formula are metered, then are respectively and uniformly mixed, are respectively added into a hopper, are melted and extruded by a multilayer co-extruder, the melting temperature is set to be 175 ℃, then enter an annular co-extrusion die head to form three-layer film extrusion, compressed air is blown in from a cooling air pipe in the center of the die head, and the film is blown into a cylindrical film or a film bubble with the blowing ratio of 2.4 and the traction ratio of 1: 10. Cooling by internal and external air, then feeding the three-layer co-extruded ultralow-temperature heat-sealing packaging film bubbles into a herringbone clamping plate to exhaust air in the three-layer co-extruded ultralow-temperature heat-sealing packaging film bubbles, then carrying out corona treatment on an inner corona machine, wherein the corona voltage is 3.8KVA, trimming and finishing the edges and corners of the film by a trimming machine, and then rolling the film by a back-to-back winding machine, and finally packaging and warehousing the film after detection.

Example 2

Inner layer:

domestic linear polyethylene material a: 55%, Japanese imported metallocene wire type material A: 22%, U.S. imported low-density polyethylene material 14.5%, opening slipping agent: 2.5%, antistatic agent: 3 percent and 3 percent of PPA master batch.

Middle layer:

japanese imported metallocene wire type B: 34%, U.S. imported low density polyethylene material 34%, domestic linear polyethylene material a: 30 percent and PPA master batch 2 percent.

Outer layer:

domestic linear polyethylene material B: 42 percent of the master batch, 43 percent of American imported metallocene wire material, 13 percent of American imported low-density polyethylene material and 2 percent of PPA master batch.

According to the formula, the outer layer formula, the middle layer formula and the inner layer formula are metered, then are respectively and uniformly mixed, are respectively added into a hopper, are melted and extruded by a multilayer co-extruder, the melting temperature is set to be 180 ℃, then enter an annular co-extrusion die head to form three-layer film extrusion, compressed air is blown in from a cooling air pipe in the center of the die head, and the film is blown into a cylindrical film or a film bubble with the blowing ratio of 2.1 and the traction ratio of 1: 11. Cooling by internal and external air, then feeding the three-layer co-extruded ultralow-temperature heat-sealing packaging film bubbles into a herringbone clamping plate to exhaust air in the three-layer co-extruded ultralow-temperature heat-sealing packaging film bubbles, then carrying out corona treatment on an inner corona machine, wherein the corona voltage is 4.0KVA, trimming and finishing the edges and corners of the film by a trimming machine, and then rolling the film by a back-to-back winding machine, and finally packaging and warehousing the film after detection.

The preparation method is used.

Indexes of the special film for packaging the polyethylene flour bag prepared in the embodiments 1 and 2 are detected according to the standard of the polyethylene blown film for packaging GB4456-2008, the indexes are superior to the national standard, and the detection results are respectively shown in tables 1 and 2.

TABLE 1

TABLE 2

Comparative example 1

The Japanese imported raw material for the inner layer and the middle layer was replaced with 2018MB of the general metallocene Exxon Mobil, and the other components were the same as in example 2, and the test results are shown in Table 3.

TABLE 3

Comparative example 2

The Japanese imported material for the middle layer was replaced with 2018MB of Exxon Mobil, a general metallocene, the other ingredients were the same as in example 2, and the test results are shown in Table 4.

TABLE 4

Comparative example 3

The Japanese imported raw material for the inner layer was replaced with 2018MB of Exxon Mobil, a general metallocene, and the results of the examination are shown in Table 5.

TABLE 5

The results show that:

after comparing the results, the heat sealing of the inner layer without adding the Japanese imported metallocene A is not firm due to the effect of the flour particles, and the strength and the light transmittance of the inner layer are changed but are not obvious.

Example 1 compared to example 2, the inner layer had a greater content of the japanese imported metallocene, so its heat sealing temperature was lower by 5 ℃, whereas in comparative example 2, no japanese imported metallocene B was added to the layer, the heat sealing temperature was 134 ℃ and the difference was 11 ℃, whereas in comparative example 1 and example 2, the amount of the inner layer openness slipping agent was different, the amount of the antistatic agent was different, and the friction coefficient of the inner layer of the film was affected, the less the antistatic agent was, the more the openness slipping agent was, and the lower the friction coefficient of the inner layer was.

Experiments prove that the heat sealing temperature of the film can be improved by adding the Japanese imported metallocene and the antistatic agent into the middle layer and the inner layer, and the friction coefficient of the inner layer can be reduced by properly reducing the using amount of the antistatic agent, so that the film surface is smoother.

Claims

1. The special film for packaging the polyethylene flour bag is prepared by adjusting the formulas of an outer layer, a middle layer and an inner layer, respectively and uniformly mixing, forming a three-layer film through a co-extrusion die head and extruding, and is characterized in that the raw material formula is as follows:

the weight percentage of each component is calculated,

inner layer:

domestic linear polyethylene material a: 50-70%, Japanese imported metallocene wire type material A: 20-30%, American imported low-density polyethylene material 5-15%, opening slipping agent: 1-3%, antistatic agent: 2-5% of PPA master batch and 1-10% of PPA master batch;

middle layer:

japanese imported metallocene wire type B: 25-45%, American imported low-density polyethylene material 15-35%, domestic linear polyethylene material A: 30-50% of PPA master batch and 1-10% of PPA master batch;

outer layer:

domestic linear polyethylene material B: 35-55%, 30-50% of American imported metallocene wire material, 5-25% of American imported low-density polyethylene material and 1-10% of PPA master batch;

2. The special film for packing polyethylene flour bags according to claim 1, wherein each component is calculated by weight percentage,

inner layer:

domestic linear polyethylene material a: 51%, Japanese imported metallocene wire type material A: 25%, American imported low-density polyethylene material 15%, opening slipping agent: 2%, antistatic agent: 4%, 3% of PPA master batch;

middle layer:

japanese imported metallocene wire type B: 35%, U.S. imported low density polyethylene material 25%, domestic linear polyethylene material a: 38%, PPA master batch 2%;

outer layer: