An interlayer easy-peeling film

Abstract

The application discloses an interlayer easy-peeling film, which comprises at least three layers of connecting layer, functional layer and heat-sealing layer which are sequentially stacked; wherein the connecting layer is a metallocene-catalyzed polyolefin material, the functional layer is a mixture of polybutene or polypropylene and polyethylene, and the heat-sealing layer is a low-stretching-property low-temperature heat-sealing material; and the polybutene or polypropylene:polyethylene is 1:1, 1:2 or 2:1. The application can control the degree of combination between the heat-sealing layer and the functional layer by adjusting the formula of the materials of the functional layer and the heat-sealing layer, that is, the peeling strength between the two layers can be controlled, so that a good peeling hand feeling can be obtained. The heat-sealing layer adopts a low-temperature heat-sealing material, and a trace of color masterbatch is added to cause visible heat-sealing transfer, which is suitable for medical packaging. Since the interlayer peeling strength between the heat-sealing layer and the functional layer is 3-5 N / 15 mm, the heat-sealing layer can be easily peeled from the functional layer, so that a stable peeling effect can be obtained.

Description

Technical Field

[0001] This invention relates to the packaging consumables manufacturing technology industry, and in particular to an easy-peel film material with superior comprehensive performance for use in medical device products and food packaging. Background Technology

[0002] Easy-peel materials are increasingly used in medical packaging, pharmaceutical packaging, and food packaging. Currently, the most commonly used easy-peel materials employ copolymer peeling and interfacial peeling methods. The main problems with these two methods are: poor visibility, meaning it's not visually clear whether the packaging's sealing film—the easy-peel material—has been separated; inconsistent peel strength, meaning it's difficult to tear the sealing film evenly by hand, resulting in a poor tearing feel; and the tendency to produce stringy residue during peeling, leading to uncleanliness.

[0003] Therefore, overcoming the shortcomings of existing packaging bags, such as poor visibility when the sealing film is peeled off, unstable peel strength, and easy stringing, is a problem that needs to be solved in this field. Summary of the Invention

[0004] To address the technical problems of poor visibility during peeling, unstable peel strength, and easy stringing in existing easy-peel packaging materials, this invention provides a superior interlayer easy-peel film with superior overall performance. This film employs an interlayer peeling method, resulting in stable packaging seal peel strength, adjustable seal peel strength, and visible opening capability.

[0005] The present invention provides an interlayer easily peelable film, comprising at least three sequentially stacked layers: a connecting layer, a functional layer, and a heat-sealing layer; wherein the connecting layer is a metallocene-catalyzed polyolefin material, the functional layer is a mixture of polybutene or polypropylene and polyethylene, and the heat-sealing layer is a low-temperature heat-sealing material with low tensile properties.

[0006] Wherein, the ratio of polybutene or polypropylene to polyethylene is 1:1, 1:2, or 2:1.

[0007] Preferably, a filler layer and a corona layer are further provided above the connecting layer.

[0008] Preferably, the corona layer is composed of 10-60% LDPE and 40-90% LLDPE.

[0009] Preferably, the filler layer consists of 10-100% LDPE and 0-90% LLDPE.

[0010] Preferably, the connecting layer is mLLDPE with a density of 0.935.

[0011] Preferably, the thickness of the heat-sealing layer is 5 to 8 micrometers.

[0012] Preferably, the heat-sealing layer is composed of a mixture of 20-50% EVA, 25-50% LLDPE, and 0-25% LDPE, and contains a color masterbatch; wherein the VA content in the EVA is 6%.

[0013] VA stands for vinyl acetate in the copolymer molecular structure. The VA content has a significant impact on the properties of EVA, determining its softness, elasticity, density, and adhesion.

[0014] Preferably, the interlayer peel strength between the functional layer and the heat-sealing layer is 3-5 N / 15 mm.

[0015] Preferably, the interlayer easily peelable film is prepared using co-extrusion blown film or co-extrusion casting equipment.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The heat-sealing strength is very stable, and the peeling feel is good. Compared with existing easy-peel film interface peeling methods, the principle of interlayer peeling is to separate the sealing film between the functional layer and the heat-sealing layer. Therefore, by adjusting the "formulation of the functional layer and heat-sealing layer materials", the degree of fusion between the heat-sealing layer and the functional layer can be controlled, thereby stably and effectively regulating the peeling strength between the two to obtain a good peeling feel.

[0018] 2. The heat-sealing layer of the easily peelable interlayer film uses low-temperature heat-sealing materials such as elastomers EVA, LLDPE, and LDPE, with a trace amount of color masterbatch added to the heat-sealing layer, resulting in visible heat-sealing layer transfer. This property is particularly suitable for medical packaging design. The color masterbatch for the heat-sealing layer can be customized according to customer requirements, and the material used is generally LLDPE as the carrier. The material formulation of the heat-sealing layer is simple and easy to implement.

[0019] 3. Easy interlayer peeling results in a clean and aesthetically pleasing film transfer interface. Due to the special formulation design employed in this invention, the actual compatibility between the heat-sealing layer and the functional layer is relatively low, and the interlayer peel strength is generally controlled at around 3-5 N / 15 mm. Furthermore, the use of a specially designed multi-layer co-extrusion equipment allows the thickness of the heat-sealing layer to be controlled at approximately 5-8 micrometers. After heat sealing, the heat-sealing layer can be easily peeled off from the functional layer upon opening, thus achieving a stable peeling effect. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0021] Figure 2This is a schematic diagram of the process flow for preparing the interlayer easily peelable film of the present invention;

[0022] Figures 3-5 These are schematic diagrams of the sealing curves for embodiments 1, 2, and 3 of the present invention.

[0023] In the diagram, 1-corona layer, 2-filler layer, 3-connector layer, 4-functional layer, 5-heat seal layer. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments, accompanying drawings, and tabular data.

[0025] Please refer to Figure 1 This invention provides a basic interlayer easily peelable film, comprising three sequentially stacked layers: a connecting layer 3, a functional layer 4, and a heat-sealing layer 5. The functional layer 4 is composed of a mixture of polybutene or polypropylene and polyethylene. The material ratio of the functional layer is: polybutene or polypropylene: polyethylene = 1:1, 1:2, or 2:1.

[0026] The connecting layer 3 (skeleton layer) of this invention is made of metallocene-catalyzed polyolefin, which is a material with good compatibility with the functional layer material. Its characteristics are: it can achieve ideal bonding strength with both incompatible materials in the functional layer 4, and the selected material has a relatively high density of approximately 0.935 and a low melt flow index, which allows for a wider heat-sealing window.

[0027] The two raw materials constituting functional layer 4—polybutene or polypropylene and polyethylene—are immiscible materials. Depending on the mixing ratio of these two materials, such as 1:1, 1:2, or 2:1, the sealing strength between functional layer 4 and heat-sealing layer 5 varies. Based on the principle of similar compatibility, the peel strength between functional layer 4 and heat-sealing layer 5 can be controlled. Heat-sealing layer 5 uses a low-temperature heat-sealing material with a thickness of 5–8 micrometers, thus controlling the interlayer peel strength between functional layer 4 and heat-sealing layer 5 to be 3–5 N / 15 mm. After heat sealing, the heat-sealing layer 5, with a trace amount of colorant added, transfers to the other side, creating a visible transfer of the heat-sealing layer.

[0028] like Figure 1 The image shows an embodiment of the five-layer easily peelable interlayer film provided by the present invention. Specifically, a filler layer 2 and a corona layer 1 are provided above the connecting layer 3 of the basically three-layer easily peelable interlayer film structure. The specific raw materials used in each layer, their proportions, and their properties are shown in Table 1.

[0029] Table 1

[0030]

[0031] Below are Examples 1 and 2 of a five-layer structure interlayer easily peelable film. Please refer to... Figure 1 :

[0032] Example 1:

[0033]

[0034] Example 2:

[0035]

[0036]

[0037] The following is Example 3 of a seven-layer structure interlayer easily peelable film.

[0038]

[0039] Note: The interlayer ratio in the above embodiments refers to the thickness ratio of each layer of the easily peelable interlayer film.

[0040] This invention can be produced using equipment for multi-layer co-extrusion blown film or multi-layer co-extrusion casting.

[0041] Please combine Figure 2 The process flow diagram shows that the preparation of easily peelable interlayer films can be carried out by basically following the process flow diagram.

[0042] The parameters of the equipment used in the preparation of this invention are convenient and easy to adjust. The screw processing temperature of the extruder can be controlled between 130 and 160°C, and the die temperature can be controlled between 170 and 200°C. A common PE screw can be used. The raw material ratio provided by this invention has wide applicability and is suitable for the production of co-extrusion equipment with three or more layers. Its process parameters can be adjusted according to different equipment. The process parameters for preparing easily peelable interlayer films are as follows:

[0043] Temperature control

[0044]

[0045]

[0046]

[0047]

[0048] The samples prepared for the examples were tested according to the following test items and standard requirements:

[0049] Sample test report:

[0050]

[0051] Heat sealing curves of three embodiments:

[0052] Example 1

[0053] Sealing strength (N / 15mm), sealing conditions: pressure 0.6MPa, time 10s

[0054] Temperature ℃ 120 125 130 135 140 Lateral sealing strength 6.649 6.424 6.427 6.839 6.589 Longitudinal sealing strength 6.258 6.558 6.702 6.772 6.792

[0055] Example 2

[0056] Sealing strength (N / 15mm), sealing conditions: pressure 0.6MPa, time 1.0s.

[0057] Temperature ℃ 120 125 130 135 140 Lateral sealing strength 2.599 2.475 3.187 3.972 3.972 Longitudinal sealing strength 2.069 2.658 2.759 3.021 3.225

[0058] Example 3

[0059] Sealing strength (N / 15mm), sealing conditions: pressure 0.6MPa, time 1.0s.

[0060] Temperature ℃ 120 125 130 135 140 Lateral sealing strength 10.788 12.310 12.093 12.210 12.543 Longitudinal sealing strength 11.474 11.640 12.406 12.248 11.720

[0061] Schematic diagrams of the sealing curves of the three embodiments described above are shown below. Figure 3 , 4 As shown in Figure 5.

[0062] The test data from the above embodiments show that the sealing strength does not change significantly with increasing heating temperature, and the lateral and longitudinal sealing strengths are also quite similar. Therefore, this invention is suitable for a wider temperature range and can handle equipment uncertainties. Furthermore, adjusting the proportions of the functional layers allows for easy adjustment of the strength to meet customer requirements. Adding color masterbatch to the heat-sealing layer provides a visible opening effect, which helps in observing the sealing effect of the packaging and effectively identifying sealing problems.

[0063] As the principle of heat-sealing peeling shows, the heat-sealing layer material and the substrate being heat-sealed (functional layer) have excellent compatibility. Therefore, heating allows the heat-sealing material and the substrate to adhere firmly together. By designing the formula and adjusting the compatibility with the heat-sealing layer, the functional layer can achieve different interlayer strengths, thus obtaining stable heat-sealing strength performance. The functional layer utilizes the incompatibility between polyethylene and polypropylene or polybutene, mixing these two materials. The resulting mixture has reduced interlayer strength with the heat-sealing layer, producing an easy peeling effect. The heat-sealing layer material EVA can provide low-temperature heat-sealing performance.

[0064] This invention controls the degree of bonding between the heat-sealing layer and the functional layer by adjusting the formulation of the functional layer and heat-sealing layer materials, thereby regulating the peel strength between them to achieve a good peel feel. The heat-sealing layer uses a low-temperature heat-sealing material with an elastomer and a trace amount of color masterbatch, resulting in visible heat-sealing transfer, making it particularly suitable for medical packaging design. Due to the relatively low actual compatibility between the heat-sealing layer and the functional layer, the interlayer peel strength is 3-5 N / 15 mm. The thickness of the heat-sealing layer is 5-8 micrometers. The heat-sealing layer can be easily peeled off from the functional layer, thus achieving a stable peel effect.

[0065] The above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An interlayer releasable film, characterized by, The film comprises at least three layers of connecting layer, functional layer and heat-sealing layer which are stacked in sequence; the connecting layer is made of metallocene-catalyzed polyolefin material, the functional layer is made of mixture of polybutene or polypropylene and polyethylene, and the heat-sealing layer is low-stretching low-temperature heat-sealing material; wherein, The polybutene or polypropylene: polyethylene = 1:1, 1:2 or 2:1; The connecting layer is mLLDPE with density of 0.935; The heat-sealing layer is made of mixture of 20-50% EVA and 25-50% LLDPE and 0-25% LDPE, and the VA content in the EVA is 6%; The interlayer peeling strength between the functional layer and the heat-sealing layer is 3-5 N / 15mm; The raw material usage is mass percentage.

2. The interlayer releasable film according to claim 1, wherein The connecting layer is further provided with filling layer and corona layer.

3. The interlayer releasable film according to claim 2, wherein The corona layer is composed of 10-60% LDPE and 40-90% LLDPE.

4. The interlayer releasable film according to claim 2, wherein The filling layer is composed of 10-100% LDPE and 0-90% LLDPE.

5. The interlayer releasable film according to claim 1, wherein The thickness of the heat-sealing layer is 5-8 microns.

6. The interlayer releasable film according to claim 1, wherein The interlayer easy-peeling film is prepared by co-extrusion blown film or co-extrusion casting equipment.

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