A barrier POF heat shrinkable printed packaging film and preparation method thereof

Abstract

The present invention discloses a barrier POF heat shrinkable printing packaging film, comprising a scratch-resistant polishing oil layer, an ink layer, a first barrier layer, a printing base layer, a second barrier layer and a heat sealing layer arranged in sequence from the outside to the inside, wherein the printing base layer and the heat sealing layer are polypropylene layers, the first barrier layer is a polyvinyl alcohol layer, and the second barrier layer is a mixed layer of linear low-density polyethylene and nylon 6. The present invention also discloses a method for preparing the barrier POF heat shrinkable printing packaging film. The barrier POF heat shrinkable printing packaging film prepared by the present invention can effectively prevent the penetration of oily substances.

Description

Technical Field

[0001] The invention belongs to the field of heat shrink film packaging, and in particular relates to a barrier POF heat shrink printed packaging film and a preparation method thereof. Background Art

[0002] POF heat shrink film is a biaxially stretched polyolefin shrink film. It is a new type of environmentally friendly heat shrink film that is currently widely used and developing rapidly. POF heat shrink film is prepared by biaxially stretched three-layer or five-layer melt co-extrusion process. It is a soft heat shrink film with high transparency, high shrinkage rate, high toughness, and high heat sealing performance. It is also antistatic and cold-resistant. It is safe and reliable. It is widely used in individual outer packaging and collective packaging of food, cosmetics, gifts, medicines, stationery, toys, audio-visual products, electronics, wood products, plastic hardware, daily necessities and other products.

[0003] However, POF heat shrink film cannot prevent the penetration of oily substances. When it is used as the outer packaging of oily substances, grease can easily penetrate the POF heat shrink film and reach the outer layer of the packaging, which will not only cause pollution of other substances outside the POF heat shrink film; but also the ink printed on the outer layer of the POF heat shrink film will fall off, resulting in the loss or unrecognition of the relevant information of the printed package. Summary of the invention

[0004] The purpose of the present invention is to provide a barrier POF heat shrinkable printing packaging film which can prevent oily substances from penetrating.

[0005] The technical solution of the present invention is:

[0006] A barrier POF heat shrinkable printed packaging film comprises a scratch-resistant varnish layer, an ink layer, a first barrier layer, a printing base layer, a second barrier layer and a heat sealing layer which are sequentially arranged from the outside to the inside, wherein the printing base layer and the heat sealing layer are polypropylene layers, the first barrier layer is a polyvinyl alcohol layer, and the second barrier layer is a mixed layer of linear low-density polyethylene and nylon 6.

[0007] The barrier POF heat shrinkable printing packaging film of the present invention has a second barrier layer which is a mixed layer of linear low-density polyethylene and nylon 6. Nylon 6 has a good oil-blocking effect and can effectively prevent the exudation of oily substances packaged in the packaging film, thereby achieving oil-blocking of the packaging film. However, the fusibility of nylon 6 and polypropylene is very poor, and pure nylon 6 cannot be fused with polypropylene to form an integrated structural film during multi-layer co-extrusion. The present invention uses a mixed layer of linear low-density polyethylene and nylon 6 as the second barrier layer. After the linear low-density polyethylene is mixed with nylon 6, it has good fusibility with polypropylene. The second barrier layer can be fused with the printing base layer and the heat sealing layer of polypropylene material to form a whole, so that the barrier POF heat shrinkable printing packaging film of the present invention has a good oil-blocking effect, which can effectively prevent the exudation of oily substances in the packaging contents, and further effectively prevent the dissolution of ink in the ink layer from causing pollution and loss of printed information. The barrier POF heat shrinkable printing packaging film of the present invention is also provided with a first barrier layer between the printing base layer and the ink layer, and the first barrier layer is a polyvinyl alcohol layer. Since the polyvinyl alcohol layer cannot penetrate oily substances, the POF heat shrinkable printed packaging film prepared therefrom forms a second oil-blocking defense line.

[0008] The two oil-blocking lines of the barrier POF heat-shrinkable printed packaging film of the present invention have different functions: the mixed layer of linear low-density polyethylene and nylon 6 is set as the second barrier layer inside the heat-sealing layer, which can effectively block the liquid macromolecular oily substances and prevent them from further penetrating into the internal dissolving ink layer of the packaging film; and the first barrier layer is set as a polyvinyl alcohol layer, which can effectively prevent the penetration of small molecular organic matter and effectively block the small molecular organic matter of the packaging film, thereby further preventing the small molecular organic matter from polluting and dissolving the ink layer, and can also prevent the loss of volatile organic small molecular substances in the inner packaging material, so that the aroma in the internal packaging such as food is not easy to be lost, thereby achieving the effect of preserving freshness and fragrance. The innermost heat-sealing layer of the barrier POF heat-shrinkable printed packaging film of the present invention is a polypropylene layer, which can maintain good adhesion when the barrier POF heat-shrinkable printed packaging film of the present invention is closed. The scratch-resistant polishing oil layer located on the outermost layer can effectively prevent scratches and protect the external damage to the printed information of the ink layer. Therefore, the barrier POF heat shrinkable printed packaging film of the present invention is arranged in multiple layers in an orderly manner according to reasonable levels, so that the layers cooperate and work together with each other, which can not only prevent pollution caused by the penetration of oily substances and the loss of printed information, but also has good preservation and fragrance preservation effects, and the bag making is firmly bonded.

[0009] Preferably, the ink layer is a chlorinated polypropylene ink layer.

[0010] Preferably, the thickness of the first barrier layer is 1-2 um. A 1-2 um polyvinyl alcohol layer can effectively prevent the loss of small organic molecules and maintain a good bonding effect with adjacent layers.

[0011] The present invention also provides a method for preparing the above-mentioned barrier POF heat shrinkable printed packaging film, comprising the following steps:

[0012] Step 1: blend linear low-density polyethylene and nylon 6 in a mass ratio of 2:1, and mix them evenly, extruding and pelletizing them through a pelletizer, and then mixing them evenly to obtain mixed pellets;

[0013] Step 2: adding the obtained mixed pellets into linear low-density polyethylene, wherein the mixed pellets account for 5-10% by weight; after hot melting, the mixed pellets are used as an intermediate layer and the inner and outer layers of polypropylene through a three-layer co-extrusion film to obtain a three-layer co-extrusion heat shrink film;

[0014] Step 3, using a 75-line, 45um-deep mesh roller to coat the polyvinyl alcohol emulsion on one side of the obtained three-layer co-extruded heat shrinkable film; drying at 40-60°C;

[0015] Step 4: Print the required graphic information on the surface of the polyvinyl alcohol layer to form an ink layer, and apply a scratch-resistant polish layer on the surface of the obtained ink layer after curing.

[0016] In the above preparation method of the present invention, linear low-density polyethylene and nylon 6 are first blended and pelletized at a mass ratio of 2:1, and then mixed and added to the linear low-density polyethylene, so that the linear low-density polyethylene and nylon 6 are mixed more fully, so as to ensure that the second barrier layer can be well combined with the printing base layer and the heat-sealing layer during the three-layer co-extrusion in step 2, and the nylon 6 with oil-blocking effect is evenly dispersed in the second barrier layer without stratification. In step 3, the polyvinyl alcohol emulsion is coated with a 75-line, 45um deep screen roller to obtain a polyvinyl alcohol layer with strong bonding force.

[0017] Preferably, the heating temperature of the extruder screw in step 2 is 200-260° C. 200-260° C. can effectively combine the polypropylene layer as the printing base layer and the heat-sealing layer with the linear low-density polyethylene and nylon 6 mixture of the second barrier layer into one, and the thickness is uniform.

[0018] Preferably, the dry coating amount of polyvinyl alcohol in step 3 is 3-8 g / m 2 3-8g / m 2 The thickness of the polyvinyl alcohol layer is 1-2um, which can effectively prevent the loss of small organic molecules and maintain a good bonding effect.

[0019] Preferably, after printing the graphic information in step 4, it needs to be cured under natural environmental conditions for 12-24 hours.

[0020] Preferably, the ink used for printing in step 4 is chlorinated polypropylene ink, 3-5% by mass of curing agent isocyanate is added to the ink, the solvent used for the ink is an ester solvent, and the ink viscosity during coating is 13-17S of 3# Zahn cup. The addition of curing agent isocyanate can make the ink layer better cured under natural conditions; the 13-17S 3# Zahn cup ink viscosity makes the graphics clearer and has good bonding during printing. If no curing agent is used, the curing time will be long.

[0021] Preferably, when the scratch-resistant polish layer is applied in step 4, the viscosity of the scratch-resistant polish is 14-18 seconds per 3# Zahn cup, and the drying temperature is 40-60°C.

[0022] Preferably, the solvent used for the polyvinyl alcohol emulsion in step 3 is an aqueous solution of ethanol, and the viscosity during coating is 14-18 seconds in a 3# Zahn cup. Using ethanol and water as solvents not only evaporates quickly but also leaves no harmful residues.

[0023] The beneficial effects of the present invention are:

[0024] The barrier POF heat shrinkable printing packaging film prepared by the preparation method of the barrier POF heat shrinkable printing packaging film of the present invention has a second barrier layer arranged between the heat sealing layer of polypropylene material and the printing base layer, and the second barrier layer uses linear low-density polyethylene and nylon 6 as a mixed layer, which effectively prevents the outflow of greasy substances in the packaging content, and further effectively prevents the dissolution of ink in the ink layer from causing pollution and loss of printed information; a first barrier layer is arranged inside the ink layer, and the first barrier layer uses a polyvinyl alcohol layer, which can effectively prevent the penetration of small molecular organic matter, prevent the small molecular organic matter from polluting and dissolving the ink layer, and make the aroma in the content packaging such as food not easy to dissipate, thereby achieving the effect of preserving freshness and fragrance. The barrier POF heat shrinkable printing packaging film of the present invention is combined into one layer, which can effectively prevent the penetration of oily substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the barrier POF heat shrinkable printed packaging film of the present invention.

[0026] In the figure: 1. scratch-resistant oil layer; 2. ink layer; 3. first barrier layer; 4. printing base layer; 5. second barrier layer; 6. heat sealing layer. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0028] like Figure 1As shown, a barrier POF heat shrinkable printed packaging film of the present invention comprises a scratch-resistant varnish layer 1, an ink layer 2, a first barrier layer 3, a printing base layer 4, a second barrier layer 5 and a heat sealing layer 6 which are arranged in sequence from the outside to the inside, wherein the printing base layer 4 and the heat sealing layer 6 are polypropylene layers, the first barrier layer 3 is a polyvinyl alcohol layer, and the second barrier layer 5 is a mixed layer of linear low-density polyethylene and nylon 6.

[0029] Example 1

[0030] A barrier POF heat shrinkable printed packaging film is prepared as follows:

[0031] Step 1: blend linear low-density polyethylene and nylon 6 in a mass ratio of 2:1, and mix them evenly, extruding and pelletizing them through a pelletizer, and then mixing them evenly to obtain mixed pellets;

[0032] Step 2: adding the obtained mixed pellets into linear low-density polyethylene, wherein the mixed pellets account for 5% by mass; after hot melting, the mixed pellets are used as the middle layer and the inner and outer layers of polypropylene through a three-layer co-extrusion film to obtain a three-layer co-extruded heat shrinkable film, and the heating temperature of the extruder screw is 260°C.

[0033] Step 3: Use a 75-line, 45-um-deep mesh roller to coat a single side of the obtained three-layer co-extruded heat shrinkable film with polyvinyl alcohol emulsion, wherein the solvent used for the polyvinyl alcohol emulsion is ethanol aqueous solution, and the viscosity during coating is 14 seconds per 3# Zahn cup; the dry basis coating amount of polyvinyl alcohol is 5 g / m 2 , drying at 40℃;

[0034] Step 4: Print the required graphic information on the surface of the polyvinyl alcohol layer with chlorinated polypropylene ink to form an ink layer. The ink contains 3% by mass of curing agent isocyanate. The solvent used in the ink is an ester solvent. The ink viscosity during coating is 3# Zahn cup 13S. Curing is carried out under natural environment for 12 hours, and then a scratch-resistant varnish layer is applied on the surface of the obtained ink layer. When the scratch-resistant varnish layer is applied, the viscosity of the scratch-resistant varnish is 3# Zahn cup 14 seconds, and the drying temperature is 40°C.

[0035] Appearance inspection: The barrier POF heat shrinkable printed packaging film obtained in this example has no wrinkles or bubbles.

[0036] Example 2

[0037] A barrier POF heat shrinkable printed packaging film is prepared as follows:

[0038] Step 1: blend linear low-density polyethylene and nylon 6 in a mass ratio of 2:1, and mix them evenly, extruding and pelletizing them through a pelletizer, and then mixing them evenly to obtain mixed pellets;

[0039] Step 2: adding the obtained mixed pellets into linear low-density polyethylene, wherein the mixed pellets account for 10% by mass; after hot melting, the mixed pellets are used as the middle layer and the inner and outer layers of polypropylene through a three-layer co-extrusion film to obtain a three-layer co-extruded heat shrinkable film, and the heating temperature of the extruder screw is 200°C.

[0040] Step 3: Use a 75-line, 45-um-deep mesh roller to coat a single side of the obtained three-layer co-extruded heat shrinkable film with polyvinyl alcohol emulsion, wherein the solvent used for the polyvinyl alcohol emulsion is ethanol aqueous solution, and the viscosity during coating is 14 seconds per 3# Zahn cup; the dry basis coating amount of polyvinyl alcohol is 3 g / m 2 , drying at 60℃;

[0041] Step 4: Print the required graphic information on the surface of the polyvinyl alcohol layer with chlorinated polypropylene ink to form an ink layer. The ink contains 3% by mass of curing agent isocyanate. The solvent used in the ink is an ester solvent. The ink viscosity during coating is 3# Zahn cup 13S. Curing is carried out under natural environment for 12 hours, and then a scratch-resistant varnish layer is applied on the surface of the obtained ink layer. When the scratch-resistant varnish layer is applied, the viscosity of the scratch-resistant varnish is 3# Zahn cup 14 seconds, and the drying temperature is 40°C.

[0042] Appearance inspection: The barrier POF heat shrinkable printed packaging film obtained in this example has no wrinkles or bubbles.

[0043] Example 3

[0044] A barrier POF heat shrinkable printed packaging film is prepared as follows:

[0045] Step 1: blend linear low-density polyethylene and nylon 6 in a mass ratio of 2:1, and mix them evenly, extruding and pelletizing them through a pelletizer, and then mixing them evenly to obtain mixed pellets;

[0046] Step 2: adding the obtained mixed pellets into linear low-density polyethylene, wherein the mixed pellets account for 5% by mass; after hot melting, the mixed pellets are used as the middle layer and the inner and outer layers of polypropylene through a three-layer co-extrusion film to obtain a three-layer co-extruded heat shrinkable film, and the heating temperature of the extruder screw is 250°C.

[0047] Step 3: Use a 75-line, 45-um-deep mesh roller to coat a single side of the obtained three-layer co-extruded heat shrinkable film with polyvinyl alcohol emulsion, wherein the solvent used for the polyvinyl alcohol emulsion is ethanol aqueous solution, and the viscosity during coating is 3# Zahn cup 18 seconds; the dry basis coating amount of polyvinyl alcohol is 8g / m 2 , drying at 50℃;

[0048] Step 4: Print the required graphic information on the surface of the polyvinyl alcohol layer with chlorinated polypropylene ink to form an ink layer. The ink contains 5% by mass of curing agent isocyanate. The solvent used in the ink is an ester solvent. The ink viscosity during coating is 3# Zahn cup 17S. Curing is carried out under natural environment for 24 hours, and then a scratch-resistant varnish layer is applied on the surface of the obtained ink layer. When the scratch-resistant varnish layer is applied, the viscosity of the scratch-resistant varnish is 3# Zahn cup 18 seconds, and the drying temperature is 60°C.

[0049] Appearance inspection: The barrier POF heat shrinkable printed packaging film obtained in this example has no wrinkles or bubbles.

[0050] Comparative Example 1

[0051] A POF heat shrinkable printed packaging film is prepared as follows:

[0052] Step 1: A three-layer co-extruded heat shrinkable film is obtained by extruding a linear low-density polyethylene as a middle layer and inner and outer layers of polypropylene through a three-layer co-extruded film, and the heating temperature of the extruder screw is 260°C.

[0053] Step 2: Print the required graphic information on the surface of the three-layer co-extruded heat shrinkable film with chlorinated polypropylene ink to form an ink layer. The ink contains 3% by mass of curing agent isocyanate. The solvent used in the ink is an ester solvent. The ink viscosity during coating is 3# Zahn cup 13S. Curing is carried out under natural environment for 12 hours, and then a scratch-resistant polish layer is applied on the surface of the obtained ink layer. When the scratch-resistant polish layer is applied, the viscosity of the scratch-resistant polish is 3# Zahn cup 14 seconds, and the drying temperature is 40°C.

[0054] Appearance inspection: The barrier POF heat shrinkable printed packaging film obtained in this comparative example has no wrinkles or bubbles.

[0055] Oil resistance performance test:

[0056] The POF heat shrinkable printed packaging films prepared in Examples 1, 2, 3 and Comparative Example 1 were tested according to the following methods. The test results are shown in Table 1.

[0057] Completely immerse the POF heat shrinkable printed packaging film in edible oil (using 1:1:1 edible vegetable blended oil of Golden Dragon Fish), leave it at room temperature for 24 hours, take it out, control the oil, and observe whether the image and text print on the ink layer is blurred, deformed, or de-inked.

[0058] Table 1

[0059] Examples Ink layer graphics Example 1 The text and images are clear without any deformation or ink loss. Example 2 The text and images are clear without any deformation or ink loss. Example 3 The text and images are clear without any deformation or ink loss. Comparative Example 1 The images and text are blurred and the colored ink can be seen in the oil.

[0060] It can be seen from the above results that the barrier POF heat shrinkable printed packaging film prepared by the method of the present invention can effectively prevent the penetration of oil. After being soaked in edible oil for 24 hours, the edible oil fails to penetrate into the ink layer to dissolve or destroy the ink layer. However, the POF heat shrinkable film prepared by the preparation method of the present invention cannot prevent the penetration of oil because the first barrier layer and the second barrier layer are not set. The oil penetrates into the ink layer to dissolve the printed ink and destroy the graphic information.

[0061] It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. For example, in the above embodiments, only chlorinated polypropylene is used as the ink layer. Those skilled in the art can easily know that printing can still be performed using other inks, and it does not affect the oil barrier properties of the barrier POF heat shrinkable printed packaging film of the present invention, and the same technical effect can be achieved. In addition, the technical features involved in the various embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. In addition, the above are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

Claims

1. A barrier POF heat shrinkable printed packaging film, characterized in that: The invention comprises a scratch-resistant varnish layer, an ink layer, a first barrier layer, a printing base layer, a second barrier layer and a heat-sealing layer arranged in sequence from the outside to the inside, wherein the printing base layer and the heat-sealing layer are polypropylene layers, the first barrier layer is a polyvinyl alcohol layer, and the second barrier layer is a mixed layer of linear low-density polyethylene and nylon 6; The ink layer is a chlorinated polypropylene ink layer; The thickness of the first barrier layer is 1-2 um.

2. A method for preparing the barrier POF heat shrinkable printing packaging film according to claim 1, characterized in that: The following steps are involved: Step 1, linear low-density polyethylene and nylon 6 are blended in a mass ratio of 2:1, and mixed to obtain mixed pellets after extrusion and pelletization by a pelletizer; Step 2: adding the obtained mixed pellets into linear low-density polyethylene, wherein the mixed pellets account for 5-10% by weight; after hot melting, the mixed pellets are used as an intermediate layer and the inner and outer layers of polypropylene through a three-layer co-extrusion film to obtain a three-layer co-extrusion heat shrink film; Step 3, using a 75-line, 45-um-deep mesh roller to coat a single side of the obtained three-layer co-extruded heat shrinkable film with polyvinyl alcohol emulsion; Dry at 40-60℃; Step 4: Print the required graphic information on the surface of the polyvinyl alcohol layer to form an ink layer, and apply a scratch-resistant polish layer on the surface of the obtained ink layer after curing.

3. The method for producing a barrier POF heat shrinkable printing packaging film according to claim 2, characterized in that: The heating temperature of the extruder screw in the step 2 is 200-260°C.

4. The method for producing a barrier POF heat shrinkable printing packaging film according to claim 2, characterized in that: The dry coating amount of polyvinyl alcohol in step 3 is 3-8 g / m 2 .

5. The method for producing a barrier POF heat shrinkable printing packaging film according to claim 2, characterized in that: After the printing information in step 4 is printed, it is cured under natural environment conditions for 12-24 hours.

6. The method for producing a barrier POF heat shrinkable printing packaging film according to claim 2, characterized in that: The ink used for printing in step 4 is chlorinated polypropylene ink, to which isocyanate, a curing agent, is added at a mass ratio of 3-5%, and the solvent used in the ink is an ester solvent. The viscosity of the ink during coating is 13-17 seconds for a 3# Zahn cup.

7. The method for producing a barrier POF heat shrinkable printing packaging film according to claim 2, characterized in that: When the scratch-resistant polish layer is applied in step 4, the viscosity of the scratch-resistant polish is 14-18 seconds for a 3# Zahn cup, and the drying temperature is 40-60°C.

8. The method for producing a barrier POF heat shrinkable printing packaging film according to claim 2, characterized in that: The solvent used for the polyvinyl alcohol emulsion in step three is ethanol aqueous solution, and the viscosity during coating is 14-18 seconds in a 3# Zahn cup.

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