阅读说明：本技术 一种单一材料复合可回收冷冻食品包装膜及其制备方法 (Single-material composite recyclable frozen food packaging film and preparation method thereof ) 是由 杨伟 顾静 陈德元 许君尉 于 2019-11-22 设计创作，主要内容包括：本发明涉及一种单一材料复合可回收冷冻食品包装膜,从上至下依次包括表层和热封层,所述表层和热封层通过胶黏剂复合在一起；其中,所述表层为经过电子交联处理的BOPE膜,厚度为20-50um；所述热封层为普通PE膜,厚度为40-80um；所述胶黏剂为无溶剂聚氨酯胶黏剂,含量低于包装膜原料总含量的1％。本发明采用单一的PE膜制作表层和热封层,回收时可直接回收而无需分离处理,从而简化了回收工序,降低了回收成本。本发明还提供了上述包装膜的制备方法,通过对表层PE膜进行双向拉伸与电子交联处理相结合的方式,大大提高了包装膜的粘合度、耐刺穿性能和耐热性能。(The invention relates to a single-material composite recyclable frozen food packaging film which sequentially comprises a surface layer and a heat sealing layer from top to bottom, wherein the surface layer and the heat sealing layer are compounded together through an adhesive; wherein the surface layer is a BOPE film subjected to electronic crosslinking treatment, and the thickness of the BOPE film is 20-50 um; the heat sealing layer is a common PE film, and the thickness of the heat sealing layer is 40-80 um; the adhesive is solvent-free polyurethane adhesive, and the content of the adhesive is lower than 1% of the total content of the raw materials of the packaging film. The surface layer and the heat sealing layer are made of the single PE film, and can be directly recycled without separation treatment during recycling, so that the recycling process is simplified, and the recycling cost is reduced. The invention also provides a preparation method of the packaging film, which greatly improves the adhesion degree, the puncture resistance and the heat resistance of the packaging film by combining the biaxial stretching and the electronic crosslinking treatment of the PE film on the surface layer.)

1. The single-material composite recyclable frozen food packaging film is characterized by sequentially comprising a surface layer and a heat sealing layer from top to bottom, wherein the surface layer and the heat sealing layer are compounded together through an adhesive; wherein the surface layer is a BOP E film subjected to electronic cross-linking treatment and has the thickness of 20-50 um; the heat sealing layer is a common PE film, and the thickness of the heat sealing layer is 40-80 um; the adhesive is solvent-free polyurethane adhesive, and the content of the adhesive is lower than 1% of the total content of the raw materials of the packaging film.

2. The method of making a single material composite recyclable frozen food packaging film as described in claim 1, comprising the steps of:

s1 preparation of PE film on surface layer

Putting the PE master batches into corresponding hoppers of an extruder, carrying out melt plasticizing and co-extrusion through a die head to obtain a semi-finished product of the surface layer PE film, then carrying out biaxial stretching treatment to obtain a BOPE film, and carrying out electronic crosslinking treatment on the BOPE film to obtain the surface layer PE film; wherein the die head temperature of the extruder is 220 ℃; setting parameters of biaxial stretching treatment: the longitudinal stretching preheating temperature is 60-70 ℃, the longitudinal stretching temperature is 100-105 ℃, the longitudinal stretching ratio is 3.5-4.2, the transverse stretching preheating temperature is 85-95 ℃, the longitudinal stretching temperature is 100-105 ℃, and the transverse stretching ratio is 3.0-4.0; parameter setting of the electronic crosslinking treatment: the linear velocity is 60m/min, the K value is 2.3, the number of quenching layers is 5, the beam current is 30mA, and the voltage is 0.2 Mv;

s2 preparation of heat-seal layer PE film

Putting the PE master batches into corresponding hoppers of an extruder, and carrying out melt plasticizing and co-extrusion through a die head to obtain a heat-sealing layer PE film, wherein the temperature of the die head of the extruder is 220 ℃;

s3 sizing and compounding

And (3) uniformly coating a layer of solvent-free polyurethane adhesive on the inner side of the heat-sealing layer PE film prepared in the step S2, enabling the inner side of the surface layer PE film prepared in the step S1 to be opposite to the heat-sealing layer PE film, then compounding the heat-sealing layer PE film and the inner side of the surface layer PE film on a solvent-free compounding machine, and curing to obtain the packaging film.

3. The method as claimed in claim 2, wherein the solvent-free polyurethane adhesive is applied in an amount of 1-2g/m in the step S3²。

4. The method as claimed in claim 2, wherein the parameters of the compounding machine in step S3 are set as follows: the compounding temperature is 50-70 ℃, and the compounding pressure is 0.2-0.4 MPa.

5. The method as claimed in claim 2, wherein the curing temperature in step S3 is 45-55 ℃ and the holding time is 48 h.

Technical Field

The invention relates to the technical field of packaging films, in particular to a single-material composite recyclable frozen food packaging film and a preparation method thereof.

Background

In the field of food packaging, polyethylene is often used for manufacturing a packaging film in a co-extrusion mode, but the polyethylene co-extrusion film has poor puncture resistance and is easy to break, so that food is leaked or oxidized in the storage and transportation processes to cause loss, and the problem is particularly prominent for frozen food.

In order to improve the problems, the invention-PE liquid packaging film and the preparation method thereof disclosed in the Chinese patent publication No. CN103481620B are modified by adding additives such as calcium carbonate, ethylene-vinyl acetate copolymer, styrene-maleic anhydride copolymer and the like into PE master batches of each layer; the invention of Chinese patent publication No. CN 108032577A, namely a high-strength clean PE film and a preparation method thereof, can achieve the purpose of modifying the high-strength clean PE film by adding high-pressure low-density polyethylene materials in an inner layer and an outer layer, although the anti-puncturing capability of the high-strength clean PE film is greatly enhanced, the difficulty of later-stage recovery of PE particles is greatly increased by adding excessive auxiliary agents in the inner layer, the polyethylene materials of different types of the outer layer are mixed to be not beneficial to separate recovery and reutilization, and the application occasions are limited if the polyethylene materials are recovered and reproduced together.

Therefore, there is a need to improve the existing frozen food packaging film to solve the above problems.

Disclosure of Invention

A first object of the present invention is to provide a single material composite recyclable frozen food packaging film.

The second purpose of the invention is to provide a preparation method of the single-material composite recyclable frozen food packaging film.

In order to achieve the purpose of the invention, the technical scheme of the invention is as follows:

the invention provides a single-material composite recyclable frozen food packaging film, which sequentially comprises a surface layer and a heat sealing layer from top to bottom, wherein the surface layer and the heat sealing layer are compounded together through an adhesive; wherein the surface layer is a BOPE film subjected to electronic crosslinking treatment, and the thickness of the BOPE film is 20-50 um; the heat sealing layer is a common PE film, and the thickness of the heat sealing layer is 40-80 um; the adhesive is solvent-free polyurethane adhesive, and the content of the adhesive is lower than 1% of the total content of the raw materials of the packaging film.

The invention provides a preparation method of the single-material composite recyclable frozen food packaging film, which comprises the following steps:

s1 preparation of PE film on surface layer

Putting the PE master batches into corresponding hoppers of an extruder, carrying out melt plasticizing and co-extrusion through a die head to obtain a semi-finished product of the surface layer PE film, then carrying out biaxial stretching treatment to obtain a BOPE film, and carrying out electronic crosslinking treatment on the BOPE film to obtain the surface layer PE film; wherein the die head temperature of the extruder is 220 ℃; setting parameters of biaxial stretching treatment: the longitudinal stretching preheating temperature is 60-70 ℃, the longitudinal stretching temperature is 100-105 ℃, the longitudinal stretching ratio is 3.5-4.2, the transverse stretching preheating temperature is 85-95 ℃, the longitudinal stretching temperature is 100-105 ℃, and the transverse stretching ratio is 3.0-4.0; parameter setting of the electronic crosslinking treatment: the linear velocity is 60m/min, the K value is 2.3, the number of quenching layers is 5, the beam current is 30mA, and the voltage is 0.2 Mv;

s2 preparation of heat-seal layer PE film

Putting the PE master batches into corresponding hoppers of an extruder, and carrying out melt plasticizing and co-extrusion through a die head to obtain a heat-sealing layer PE film, wherein the temperature of the die head of the extruder is 220 ℃;

s3 sizing and compounding

And (3) uniformly coating a layer of solvent-free polyurethane adhesive on the inner side of the heat-sealing layer PE film prepared in the step S2, enabling the inner side of the surface layer PE film prepared in the step S1 to be opposite to the heat-sealing layer PE film, then compounding the heat-sealing layer PE film and the inner side of the surface layer PE film on a solvent-free compounding machine, and curing to obtain the packaging film.

Further, said is freeThe gluing amount of the solvent polyurethane adhesive is 1-2g/m²。

Further, the parameters of the compound machine are set as: the compounding temperature is 50-70 ℃, and the compounding pressure is 0.2-0.4 MPa.

Further, the curing temperature is 45-55 ℃, and the holding time is 48 h.

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

1. the surface layer and the heat sealing layer are made of a single PE film, and the content of the adhesive is negligible, so that the PE film can be directly recycled without separation treatment during recycling, thereby simplifying the recycling process and reducing the recycling cost;

2. the surface layer PE film is subjected to electronic cross-linking treatment after being subjected to biaxial stretching treatment, so that the puncture resistance and high temperature resistance of the packaging film are improved, and the adhesion degree of the packaging film is improved, so that the packaging film is not easy to tear in the use process;

3. the frozen food packaging film disclosed by the invention is simple in preparation method, strong in puncture resistance, not easy to damage, easy to recycle and capable of being widely popularized and applied to the field of food packaging.

Detailed Description

The single-material composite recyclable frozen food packaging film sequentially comprises a surface layer and a heat sealing layer from top to bottom, wherein the surface layer and the heat sealing layer are compounded together through an adhesive; wherein the surface layer is a BOPE film subjected to electronic crosslinking treatment, and the thickness of the BOPE film is 20-50 um; the heat sealing layer is a common PE film, and the thickness of the heat sealing layer is 40-80 um; the adhesive is solvent-free polyurethane adhesive, and the content of the adhesive is lower than 1% of the total content of the raw materials of the packaging film.

The preparation method of the single-material composite recyclable frozen food packaging film comprises the following steps:

s1 preparation of PE film on surface layer

Putting the PE master batches into corresponding hoppers of an extruder, carrying out melt plasticizing and co-extrusion through a die head to obtain a semi-finished product of the surface layer PE film, then carrying out biaxial stretching treatment to obtain a BOPE film, and carrying out electronic crosslinking treatment on the BOPE film to obtain the surface layer PE film; wherein the die head temperature of the extruder is 220 ℃; setting parameters of biaxial stretching treatment: the longitudinal stretching preheating temperature is 60-70 ℃, the longitudinal stretching temperature is 100-105 ℃, the longitudinal stretching ratio is 3.5-4.2, the transverse stretching preheating temperature is 85-95 ℃, the longitudinal stretching temperature is 100-105 ℃, and the transverse stretching ratio is 3.0-4.0; parameter setting of the electronic crosslinking treatment: the linear velocity is 60m/min, the K value is 2.3, the number of quenching layers is 5, the beam current is 30mA, and the voltage is 0.2 Mv;

s2 preparation of heat-seal layer PE film

Putting the PE master batches into corresponding hoppers of an extruder, and carrying out melt plasticizing and co-extrusion through a die head to obtain a heat-sealing layer PE film, wherein the temperature of the die head of the extruder is 220 ℃;

s3 sizing and compounding

And (3) uniformly coating a layer of solvent-free polyurethane adhesive on the inner side of the heat-sealing layer PE film prepared in the step S2, enabling the inner side of the surface layer PE film prepared in the step S1 to be opposite to the heat-sealing layer PE film, then compounding the heat-sealing layer PE film and the inner side of the surface layer PE film on a solvent-free compounding machine, and curing to obtain the packaging film.

Further, the gluing amount of the solvent-free polyurethane adhesive is 1-2g/m²。

Further, the parameters of the compound machine are set as: the compounding temperature is 50-70 ℃, and the compounding pressure is 0.2-0.4 MPa.

Further, the curing temperature is 45-55 ℃, and the holding time is 48 h.

The present invention will be further described with reference to the following specific examples.