An anti-counterfeiting cavitation label film with low interlayer bonding force and a preparation method thereof

Abstract

The present invention relates to an anti-counterfeiting cavitation label film with low interlayer bonding force and a preparation method thereof, and belongs to the technical field of anti-counterfeiting labels. The anti-counterfeiting cavitation label film with low interlayer bonding force of the present invention comprises a first surface layer, a first surface layer, a core layer, a second surface layer and a second surface layer arranged in sequence; the first surface layer comprises polypropylene and 60-75wt% inorganic matte masterbatch, the inorganic matte masterbatch comprises polypropylene and 25-50wt% calcium carbonate or silicon dioxide, and the particle size D50 of the calcium carbonate or the silicon dioxide in the inorganic matte masterbatch is 0.5-1μm; the core layer comprises polypropylene and pearlescent masterbatch; the second surface layer comprises polypropylene and 9-12wt% ethylene-5-norbornene-2-methanol copolymer. After the label made of the anti-counterfeiting cavitation label film with low interlayer bonding force as a substrate is pasted on a product, interlayer separation phenomenon is likely to occur when the label is peeled off from the product, thereby destroying the label, which plays a role in improving the anti-counterfeiting ability of the label.

Description

Technical Field

[0001] The invention relates to the technical field of anti-counterfeiting labels, and in particular to an anti-counterfeiting cavitation label film with low interlayer bonding force and a preparation method thereof. Background Art

[0002] Product manufacturers establish their product image and brand image through excellent product quality and product effects. With the increasing abundance of material goods, when consumers have more choices in goods, brand image becomes a key factor for consumers to buy goods. The brand image is generally displayed by sticking labels with the brand's characteristic patterns and texts on the surface of the products it produces. At present, there are many kinds of labels on the market. Most of them are made of film as the base material and are made by printing on the surface of the film, such as wraparound labels made of transparent glossy film or pearl film through multi-color gravure printing, and self-adhesive labels made of pearl film through UV printing.

[0003] When using labels, hot melt adhesive or self-adhesive adhesive is generally used to stick the labels on products (such as PET or HDPE bottles). However, since the bonding strength between hot melt adhesive or self-adhesive adhesive and labels is higher than that between hot melt adhesive or self-adhesive adhesive and products, some lawless elements can easily tear off the labels together with the hot melt adhesive or self-adhesive adhesive and re-stick them on other counterfeit products, which reduces the anti-counterfeiting effect of the original product and affects the reputation of the original product. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide an anti-counterfeiting cavitation label film with low interlayer bonding force and a preparation method thereof. After a label made of the anti-counterfeiting cavitation label film with low interlayer bonding force as a substrate is pasted on a product (such as a PET or HDPE bottle), interlayer separation is likely to occur when the label is peeled off from the product, thereby destroying the label, thereby improving the anti-counterfeiting ability of the label.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A low interlayer bonding force anti-counterfeiting cavitation label film comprises a first surface layer, a first surface layer, a core layer, a second surface layer and a second surface layer which are arranged in sequence; the first surface layer comprises polypropylene and 60-75wt% of an inorganic matte masterbatch, the inorganic matte masterbatch comprises polypropylene and 25-50wt% of calcium carbonate or silicon dioxide, and the particle size D50 of the calcium carbonate or the silicon dioxide in the inorganic matte masterbatch is 0.5-1μm; the core layer comprises polypropylene and a pearlescent masterbatch; the second surface layer comprises polypropylene and 9-12wt% of an ethylene-5-norbornene-2-methanol copolymer.

[0007] The anti-counterfeiting cavitation label film with low interlayer bonding force described in the present invention forms a "cavitation" structure in the core layer by adding pearlescent masterbatch to the core layer, and by setting the first surface layer and the second surface layer, the interlayer bonding force between the first surface layer and the core layer, and between the second surface layer and the core layer is low, and interlayer separation is easy to occur under the action of external force. Therefore, when the anti-counterfeiting cavitation label film with low interlayer bonding force is used as a label made of a substrate and pasted on a product, interlayer separation is easy to occur when the label is peeled off from the product, causing interlayer separation between the first surface layer and the core layer, and / or interlayer separation between the second surface layer and the core layer, thereby destroying the label, improving the anti-counterfeiting ability of the label, and playing a role of double anti-counterfeiting insurance.

[0008] The anti-counterfeiting cavitation label film with low interlayer bonding force described in the present invention comprises polypropylene and pearlescent masterbatch in the core layer. The effective components of the pearlescent masterbatch generate cavities in the core layer by mechanical foaming during the film production process. Specifically, during the stretching process of the film production process, since the interfacial bonding force between polypropylene and the effective components of the pearlescent masterbatch is less than the strength of polypropylene itself, polypropylene and the effective components of the pearlescent masterbatch are separated to form "cavities". After the film is formed, the "cavity" shape is fixed, so that the core layer of the anti-counterfeiting cavitation label film with low interlayer bonding force forms a structure with "cavities". Since there is no filler in the "cavity" structure, the interlayer bonding force between the core layer and the first surface layer and the second surface layer is mainly provided by the polypropylene around the "cavity" structure of the core layer. On the basis of the core layer, the present invention further designs the components of the first surface layer and the second surface layer, so that the core layer and the first surface layer, and the core layer and the second surface layer, can not only not have interlayer separation during film production, but also have the characteristics of low interlayer bonding force.

[0009] The first surface layer includes polypropylene and 60-75wt% inorganic matte masterbatch, the inorganic matte masterbatch includes polypropylene and 25-50wt% calcium carbonate or silicon dioxide, and the particle size D50 of the calcium carbonate or silicon dioxide in the inorganic matte masterbatch is 0.5-1μm. The present invention adds the inorganic matte masterbatch to the first surface layer, limits the content of the calcium carbonate or silicon dioxide in the inorganic matte masterbatch to 25-50wt%, and limits the particle size D50 of the calcium carbonate or silicon dioxide in the inorganic matte masterbatch to 0.5-1μm, so that the first surface layer has a matte effect and forms a rough morphological structure. Specifically, the first surface layer utilizes the principle that the calcium carbonate or the silicon dioxide is incompatible with polypropylene, and limits the particle size D50 of the calcium carbonate or the silicon dioxide in the inorganic matte masterbatch to 0.5-1 μm, so that the first surface layer produces smaller holes (or no holes) during the stretching process of the film production process, and the calcium carbonate or the silicon dioxide protrudes from the first surface layer and can be embedded in the first surface layer or the core layer, so that the contact area between the calcium carbonate or the silicon dioxide in the first surface layer and the core layer and the polypropylene of the first surface layer is increased, and the contact area between the polypropylene in the first surface layer and the upper surface layer and the core layer is reduced, which plays a "cable breaking" role, thereby reducing the interlayer bonding force between the first surface layer and the core layer. If the content of the calcium carbonate or the silicon dioxide in the inorganic matte masterbatch is too low, and / or the content of the inorganic matte masterbatch in the first surface layer is too low, it is not conducive to the calcium carbonate or the silicon dioxide in the inorganic matte masterbatch protruding from the first surface layer, and it cannot play a role in reducing the interlayer bonding force between the first surface layer and the core layer; if the content of the calcium carbonate or the silicon dioxide in the inorganic matte masterbatch is too high, and / or the content of the inorganic matte masterbatch in the first surface layer is too high, it is easy to cause the interlayer bonding force between the first surface layer and the core layer to be too low, and even interlayer delamination occurs during film production, making it impossible to produce the film smoothly. The present invention limits the selection of calcium carbonate or silicon dioxide with a particle size D50 of 0.5-1μm as the effective component of the inorganic matte masterbatch, so that effective and uniform continuous protrusions can be formed in the first surface layer. If the particle size D50 of the calcium carbonate or the silica in the inorganic matte masterbatch is too small, protrusions cannot be effectively formed in the first surface layer; if the particle size D50 of the calcium carbonate or the silica in the inorganic matte masterbatch is too large, the amount of the calcium carbonate or the silica is reduced, and the calcium carbonate or the silica cannot form uniform and continuous protrusions after being dispersed in the first surface layer.

[0010] The second surface layer includes polypropylene and 9-12wt% ethylene-5-norbornene-2-methanol copolymer. The norbornene in the ethylene-5-norbornene-2-methanol copolymer has a ring structure and plays the role of hardened protrusions; the polar alcoholic hydroxyl group in the ethylene-5-norbornene-2-methanol copolymer is conducive to improving the binding force between the second surface layer and the effective components of the pearlescent masterbatch in the core layer, but reduces the binding force between the second surface layer and the polypropylene in the core layer; through the hardening protrusion of the ring structure of norbornene, combined with the role of polar alcoholic hydroxyl groups, the interlayer bonding force between the second surface layer and the core layer is low. In this way, after the anti-counterfeiting cavitation label film with low interlayer bonding force is made into a label and pasted on the product, it is more conducive to the polypropylene around the "hole" of the core layer (the position with the weakest interlayer bonding force) to produce delamination when torn off, thereby improving the anti-counterfeiting effect. In addition, the cyclic structure of norbornene also has a certain barrier effect, which is conducive to ensuring the viscosity of the glue (such as hot melt glue or self-adhesive glue) between the label and the product, preventing other substances from migrating or penetrating to the position of the glue between the label and the product, affecting the adhesion between the label and the product, and making the label and the product more firmly bonded. In the second surface layer, the content of the ethylene-5-norbornene-2-methanol copolymer is 9-12wt%. If the content of the ethylene-5-norbornene-2-methanol copolymer in the second surface layer is too low, the effect of increasing the polypropylene around the "hole" (the position where the interlayer bonding force is the weakest) to produce delamination is not obvious (that is, it will increase the bonding force between the core layer and the second surface layer, which is not conducive to delamination); if the content of the ethylene-5-norbornene-2-methanol copolymer in the second surface layer is too high, due to the high content of polar groups (alcohol hydroxyl groups), the hydrogen bonding force between molecular chains is too large, which will cause the second surface layer to be too brittle, which is not conducive to biaxial stretching, and stratification is prone to occur during the stretching process.

[0011] Therefore, the present invention designs the first surface layer and the second surface layer so that the core layer and the first surface layer, and the core layer and the second surface layer, can not only avoid interlayer separation during film production, but also have the characteristics of low interlayer bonding force. Due to the existence of the "hole" structure in the core layer and the design of the first surface layer and the second surface layer, the interlayer bonding force of the anti-counterfeiting cavitation label film with low interlayer bonding force along the cross section is reduced, and the polypropylene around the "hole" of the core layer becomes the position with the weakest interlayer bonding force. When the applied force is greater than the interlayer bonding force at this position, the film will produce a delamination phenomenon, causing interlayer separation between the first surface layer and the core layer, and / or interlayer separation between the second surface layer and the core layer, and the delamination phenomenon is an irreversible process. The anti-counterfeiting cavitation label film with low interlayer bonding force of the present invention can be printed on the first surface layer to make a label, and then be pasted on the product by applying hot melt adhesive or adhesive on the second surface layer (the surface facing the product (such as PET or HDPE bottle) when labeling) on ​​the label. If interlayer separation occurs when peeling the label from the product, the first surface layer and the core layer will be separated, and / or the second surface layer and the core layer will be separated, thereby destroying the label, improving the anti-counterfeiting ability of the label, and playing the role of double anti-counterfeiting insurance.

[0012] As a preferred solution of the present invention, the polypropylene in the first surface layer and the polypropylene in the inorganic matte masterbatch are copolymerized polypropylene or homopolymerized polypropylene.

[0013] As a preferred solution of the present invention, the polypropylene in the second surface layer is homopolymer polypropylene.

[0014] As a preferred embodiment of the present invention, in the second surface layer, the intrinsic viscosity of the ethylene-5-norbornene-2-methanol copolymer is 0.2-1dL / g. By limiting the intrinsic viscosity of the ethylene-5-norbornene-2-methanol copolymer to 0.2-1dL / g, it is beneficial to its melt flow matching with polypropylene and to biaxial stretching film formation.

[0015] As a preferred embodiment of the present invention, in the second surface layer, the content of 5-norbornene-2-methanol in the ethylene-5-norbornene-2-methanol copolymer is 3-6 mol%. By limiting the content of 5-norbornene-2-methanol to 3-6 mol%, it is more conducive to the polypropylene around the "hole" of the core layer (the position with the weakest interlayer bonding force) to produce delamination when the anti-counterfeiting cavitation label film with low interlayer bonding force is made into a label and pasted on the product, thereby improving the anti-counterfeiting effect.

[0016] As a preferred solution of the present invention, the polypropylene in the core layer is homopolymer polypropylene, which can give the film excellent physical and mechanical properties and provide mechanical strength for the film.

[0017] As a preferred solution of the present invention, the content of the pearlescent masterbatch in the core layer is 3-15wt%; the pearlescent masterbatch includes polypropylene and 50-80wt% polymer or calcium carbonate, the polypropylene in the pearlescent masterbatch is homopolymer polypropylene, and the polymer is a polymer incompatible with polypropylene. The effective component of the pearlescent masterbatch is the polymer or calcium carbonate, which provides a "cavitation" effect for the film, thereby providing a pearlescent effect for the film. The polymer or calcium carbonate is an effective component of the pearlescent masterbatch. During the stretching process of the film production process, the interface bonding force between the polymer or calcium carbonate and the polypropylene is less than the strength of the polypropylene itself, so that the polypropylene and the polymer or calcium carbonate are separated to form "cavities".

[0018] As a preferred embodiment of the present invention, the particle size D50 of the calcium carbonate in the pearlescent masterbatch is 1.0-1.5 μm. The particle size D50 of the calcium carbonate or the silicon dioxide in the inorganic matte masterbatch in the first surface layer is smaller than the particle size D50 of the calcium carbonate in the pearlescent masterbatch in the core layer. The pearlescent masterbatch uses calcium carbonate in the above-mentioned particle size range as an effective ingredient, which can obtain a relatively uniform "cavitation" effect, avoiding the mechanical strength of a local position being enhanced due to the poor "cavitation" effect, thereby affecting the delamination effect. After the filterability test, the pressure change of the pearlescent masterbatch prepared with calcium carbonate in the above-mentioned particle size range is <1.0 bar / 10g. The filterability test method is as follows: pass 1.0 kg of the masterbatch melt through a 1250 mesh filter, and observe the pressure change before the filter.

[0019] As a preferred embodiment of the present invention, the core layer further comprises 1-5wt% white masterbatch; the white masterbatch comprises polypropylene and 50-70wt% titanium dioxide. Adding the white masterbatch to the core layer can provide a light shielding effect for the anti-counterfeiting cavitation label film with low interlayer bonding force of the present invention. The above range does not represent a limitation of the present invention, and those skilled in the art can adjust the proportion of the white masterbatch according to actual needs with the light transmittance as an indicator.

[0020] As a preferred solution of the present invention, further, the particle size D50 of titanium dioxide in the white masterbatch is 400-800 nm. By limiting the particle size of titanium dioxide in the white masterbatch, the light shielding effect of the core layer is made uniform.

[0021] In some embodiments, those skilled in the art can add antistatic agents, lubricants and other additives to the core layer according to actual needs to improve the performance of the film. For example, 0-2wt% antistatic agent and 0-2wt% lubricant are added to the core layer.

[0022] As a preferred solution of the present invention, the first surface layer is a bright layer or a matte layer. When the first surface layer is a bright layer, the first surface layer comprises 90-100wt% polypropylene and 0-10wt% anti-blocking masterbatch, and the polypropylene in the first surface layer is copolymerized polypropylene or homopolymerized polypropylene; when the first surface layer is a matte layer, the first surface layer comprises 90-100wt% matte masterbatch and 0-10wt% anti-blocking masterbatch, and the matte masterbatch comprises copolymerized polypropylene and 30-70wt% low-pressure high-density polyethylene.

[0023] As a preferred embodiment of the present invention, the second surface layer is a bright layer or a matte layer. When the second surface layer is a bright layer, the second surface layer comprises 90-100wt% polypropylene and 0-10wt% anti-blocking masterbatch, and the polypropylene in the second surface layer is copolymerized polypropylene or homopolymerized polypropylene. When the second surface layer is a matte layer, the second surface layer comprises 90-100wt% matte masterbatch and 0-10wt% anti-blocking masterbatch, and the matte masterbatch comprises copolymerized polypropylene and 30-70wt% low-pressure high-density polyethylene.

[0024] The first surface layer in the anti-counterfeiting cavitation label film with low interlayer bonding strength of the present invention is used as a printing surface. Those skilled in the art can select the specific components of the first surface layer according to actual needs or according to the printing method. For example, when the anti-counterfeiting cavitation label film with low interlayer bonding strength is applied to a label, the printing ink thickness is 2 μm, which is suitable for printing a glossy layer, and the first surface layer can be selected as a glossy layer. If the ink thickness is large (for example, using a screen printing method), it is sufficient to cover the roughened matte surface, so the printing surface can also be selected to use a matte surface, that is, the first surface layer can be selected as a matte layer.

[0025] As a preferred solution of the present invention, when the polypropylene in each layer of the anti-counterfeiting cavitation label film with low interlayer bonding force is selected as copolymer polypropylene, the polypropylene in each layer can be independently selected from the copolymer polypropylene with the following melt index and melting point: the melting point of the copolymer polypropylene is 120-150°C, and the melt index is 6-10g / 10min. When the polypropylene in each layer of the anti-counterfeiting cavitation label film with low interlayer bonding force is selected as homopolymer polypropylene, the polypropylene in each layer can be independently selected from the homopolymer polypropylene with the following melt index and melting point: the melting point of the homopolymer polypropylene is 160-180°C, and the melt index is 2-4g / 10min. Too high a melt index will reduce the heat resistance and mechanical properties of the film, and too low a melt index will reduce the ductility of the material, making it difficult to carry out an effective stretching process, and increasing the risk of smoothness problems such as film breakage and poor stretching.

[0026] As a preferred solution of the present invention, when the polypropylene in each layer of the anti-counterfeiting cavitation label film with low interlayer bonding force is selected as homopolymer polypropylene, those skilled in the art can select commercially available homopolymer polypropylene such as FS3011E, T36F, L5D98, PPH-F03, H3035, T38, etc. according to actual needs.

[0027] As a preferred solution of the present invention, the total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force is 35-70 μm, and the apparent density is 0.55-0.80 g / cm 3 ; The thickness of the first surface layer and the second surface layer is 1.5-5.0 μm respectively; The thickness of the first surface layer and the second surface layer is 1.5-3.5 μm respectively; The total thickness of the first surface layer and the first surface layer is 3.0-10.0% of the total thickness of the whole film. If the total thickness of the first surface layer and the first surface layer accounts for less than 3.0wt% of the total thickness of the whole film, the melt may flow back under the high pressure state of other extruders due to the low extrusion amount of the first surface layer and the first surface layer; If the total thickness of the first surface layer and the first surface layer accounts for more than 10.0wt% of the total thickness of the whole film, the strength of the polypropylene of the first surface layer and the first surface layer will become the main factor determining the interlayer bonding force, and the first surface layer, the first surface layer and the core layer will not be separated during the film production process, and the core layer and the first surface layer are not easy to separate under the action of external force, and the anti-counterfeiting effect cannot be effectively achieved.

[0028] The present invention also provides a method for preparing an anti-counterfeiting cavitation label film with low interlayer bonding force, comprising the following steps:

[0029] The raw materials of each layer are added to each extruder to form a homogenized melt, and the melt is filtered and then co-extruded through a die head in multiple layers;

[0030] Then, according to the flat film method, the cast sheet is quenched into a thick sheet, and the thick sheet is made into a biaxially stretched film by a method of first longitudinally and then transversely or longitudinally and transversely simultaneously biaxially stretching; or according to the tubular film method, the melt is separated from the mold to form a primary tubular film, which is then quenched and then transversely inflated and longitudinally stretched to form a biaxially stretched film;

[0031] After cooling, the film is subjected to corona treatment, flame treatment or plasma treatment, and then rolled into a mother roll. After the mother roll is subjected to aging treatment, it is slit into finished products.

[0032] In the above process:

[0033] (1) Melt extrusion temperature:

[0034] The first surface layer or the second surface layer is a bright layer: when the first surface layer or the second surface layer is a bright layer, and the polypropylene of the first surface layer or the second surface layer is copolymerized polypropylene, the melt extrusion temperature of the first surface layer or the second surface layer is 200-260°C; when the first surface layer or the second surface layer is a bright layer, and the polypropylene of the first surface layer or the second surface layer is homopolymerized polypropylene, the melt extrusion temperature of the first surface layer or the second surface layer is 230-260°C; when the first surface layer or the second surface layer is a matte layer, the melt extrusion temperature of the first surface layer or the second surface layer is 220-260°C;

[0035] Core layer: melt extrusion temperature is 230-260℃;

[0036] First surface layer: when the polypropylene in the first surface layer is homopolymer polypropylene, the melt extrusion temperature of the first surface layer is 230-260°C; when the polypropylene in the first surface layer is copolymer polypropylene, the melt extrusion temperature of the first surface layer is 200-260°C.

[0037] Second surface layer: melt extrusion temperature is 230-260℃.

[0038] (2) Chilling water and chilling roller temperature: 15℃-50℃.

[0039] (3) Temperature in longitudinal stretching zone:

[0040] When the first surface layer or the second surface layer is a bright layer, and the polypropylene of the first surface layer or the second surface layer is copolymerized polypropylene, the temperature of the longitudinal stretching zone of the first surface layer or the second surface layer is 80°C-130°C; when the first surface layer or the second surface layer is a bright layer, and the polypropylene of the first surface layer or the second surface layer is homopolymerized polypropylene, the temperature of the longitudinal stretching zone of the first surface layer or the second surface layer is 100-135°C; when the first surface layer or the second surface layer is a matte layer, the temperature of the longitudinal stretching zone of the first surface layer or the second surface layer is 90-135°C;

[0041] (4) Transverse stretching zone temperature: 140-180°C;

[0042] (5) Stretching ratio: longitudinal stretching ratio: 4.5-5.5 times; transverse stretching ratio: 8-10 times.

[0043] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The schematic diagram of the structure of an anti-counterfeiting cavitation label film with low interlayer bonding force of the present invention. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with examples. These examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually carried out according to conventional conditions in the art or according to the conditions recommended by the manufacturer; the raw materials, reagents, etc. used, unless otherwise specified, are all raw materials and reagents that can be obtained from commercial channels such as conventional markets. Any non-substantial changes and substitutions made by those skilled in the art on the basis of the present invention belong to the scope of protection claimed by the present invention.

[0046] In the following examples or comparative examples:

[0047] Anti-blocking masterbatch: composed of 5wt% silica and 95wt% homopolymer polypropylene.

[0048] Inorganic matte masterbatch: It is composed of 30wt% calcium carbonate and 70wt% homopolymer polypropylene, wherein the particle size of calcium carbonate is 0.8μm.

[0049] Pearlescent masterbatch: It is composed of 60wt% calcium carbonate and 40wt% homopolymer polypropylene, wherein the particle size of calcium carbonate is 1.5μm.

[0050] White masterbatch: It is composed of 60wt% titanium dioxide and 40wt% homopolymer polypropylene, wherein the particle size of titanium dioxide is 500nm.

[0051] In the following examples and comparative examples, the melt index of copolymerized polypropylene is 6 g / 10 min and the melting point is 130°C, and the melt index of homopolymerized polypropylene is 3 g / 10 min and the melting point is 166°C.

[0052] Example 1

[0053] This embodiment provides an anti-counterfeiting cavitation label film with low interlayer bonding force. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a bright layer, and the second surface layer 5 is a matte layer. Specifically, the formula of each layer is as follows:

[0054] The first surface layer 1 comprises: 96 wt % copolymerized polypropylene and 4 wt % anti-blocking masterbatch;

[0055] First surface layer 2: 30wt% homopolymer polypropylene and 70wt% inorganic matte masterbatch;

[0056] Core layer 3: 84.0wt% homopolypropylene, 14.0wt% pearlescent masterbatch and 2.0wt% white masterbatch;

[0057] Second surface layer 4: 90 wt% homopolypropylene and 10 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity is 0.5 dL / g, and the content of 5-norbornene-2-methanol is 5 mol%);

[0058] Second surface layer 5: 50wt% copolymerized polypropylene and 50wt% low pressure high density polyethylene.

[0059] This embodiment also provides a method for preparing an anti-counterfeiting cavitation label film with low interlayer bonding force, comprising the following steps:

[0060] The raw materials of each layer are added to each extruder to form a homogenized melt. The melt is filtered and then co-extruded through a die head. Then, according to the flat film method, the cast sheet is chilled into a thick sheet, and the thick sheet is made into a biaxially stretched film by a biaxial stretching method, first longitudinally and then transversely. After cooling, the film is subjected to corona treatment and then rolled into a mother roll. After the mother roll is subjected to aging treatment, it is slit into finished products.

[0061] In the above process, the melt extrusion temperature of the first surface layer 1 is 200-260°C, the melt extrusion temperatures of the first surface layer 2, the core layer 3 and the second surface layer 4 are all 230-260°C, and the melt extrusion temperature of the second surface layer 5 is 220-260°C; the cooling temperature of the chilled water and the chilled roller is 15-50°C; the temperature of the longitudinal stretching zone of the first surface layer 1 is 80-130°C, and the temperature of the longitudinal stretching zone of the second surface layer 5 is 90-135°C; the temperature of the transverse stretching zone is 140-180°C; the longitudinal stretching ratio is 4.5-5.5, and the transverse stretching ratio is 8-10.

[0062] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is 60.0 μm, wherein the thickness of the first surface layer 1 is 1.8 μm, the thickness of the first surface layer 2 is 2.0 μm, the thickness of the core layer 3 is 52.4 μm, the thickness of the second surface layer 4 is 2.0 μm, and the thickness of the second surface layer 5 is 1.8 μm.

[0063] Example 2

[0064] This embodiment provides an anti-counterfeiting cavitation label film with low interlayer bonding force. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a glossy layer, and the second surface layer 5 is a glossy layer. Specifically, the formula of each layer is as follows:

[0065] The first surface layer 1 comprises: 98 wt% copolymerized polypropylene and 2 wt% anti-blocking masterbatch;

[0066] First surface layer 2: 25wt% copolymerized polypropylene and 75wt% inorganic matte masterbatch;

[0067] Core layer 3: 86.5wt% homopolypropylene, 10.0wt% pearlescent masterbatch and 3.5wt% white masterbatch;

[0068] Second surface layer 4: 90 wt% homopolypropylene and 10 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity is 0.5 dL / g, and the content of 5-norbornene-2-methanol is 5 mol%);

[0069] Second surface layer 5: 98wt% homopolypropylene+2wt% anti-blocking masterbatch.

[0070] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is basically the same as that in Embodiment 1, except that: the melt extrusion temperature of the second surface layer 5 is 230-260°C; the temperature of the longitudinal stretching zone of the second surface layer 5 is 100-135°C.

[0071] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is 68.0 μm, wherein the thickness of the first surface layer 1 is 1.5 μm, the thickness of the first surface layer 2 is 2.5 μm, the thickness of the core layer 3 is 59.7 μm, the thickness of the second surface layer 4 is 2.5 μm, and the thickness of the second surface layer 5 is 1.8 μm.

[0072] Example 3

[0073] This embodiment provides an anti-counterfeiting cavitation label film with low interlayer bonding force. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a bright layer, and the second surface layer 5 is a matte layer. Specifically, the formula of each layer is as follows:

[0074] The first surface layer 1 comprises: 96 wt % copolymerized polypropylene and 4 wt % anti-blocking masterbatch;

[0075] First surface layer 2: 40wt% homopolymer polypropylene and 60wt% inorganic matte masterbatch;

[0076] Core layer 3: 82.5wt% homopolypropylene, 16.0wt% pearlescent masterbatch and 1.5wt% white masterbatch;

[0077] Second surface layer 4: 91 wt% homopolypropylene and 9 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity is 1 dL / g, and the content of 5-norbornene-2-methanol is 6 mol%);

[0078] Second surface layer 5: 50wt% copolymerized polypropylene and 50wt% low pressure high density polyethylene.

[0079] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is the same as that in embodiment 1.

[0080] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is 68.0 μm, wherein the thickness of the first surface layer 1 is 2.0 μm, the thickness of the first surface layer 2 is 4.5 μm, the thickness of the core layer 3 is 58.0 μm, the thickness of the second surface layer 4 is 2.0 μm, and the thickness of the second surface layer 4 is 1.5 μm.

[0081] Example 4

[0082] This embodiment provides an anti-counterfeiting cavitation label film with low interlayer bonding force. Figure 1, including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a bright layer, and the second surface layer 5 is a matte layer. Specifically, the formula of each layer is as follows:

[0083] The first surface layer 1 comprises: 97 wt% homopolypropylene and 3 wt% anti-blocking masterbatch;

[0084] First surface layer 2: 25wt% copolymerized polypropylene and 75wt% inorganic matte masterbatch;

[0085] Core layer 3: 83.5wt% homopolypropylene, 15.0wt% pearlescent masterbatch and 1.5wt% white masterbatch;

[0086] Second surface layer 4: 88 wt% homopolypropylene and 12 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity is 12 dL / g, 5-norbornene-2-methanol content is 3 mol%);

[0087] Second surface layer 5: 50wt% copolymerized polypropylene and 50wt% low pressure high density polyethylene.

[0088] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is basically the same as that in Example 1, except that: the melt extrusion temperature of the first surface layer 1 is 230-260°C, the melt extrusion temperature of the first surface layer 2 is 200-260°C; the temperature of the longitudinal stretching zone of the first surface layer 1 is 100-135°C.

[0089] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is 60.0 μm, wherein the thickness of the first surface layer 1 is 2.1 μm, the thickness of the first surface layer 2 is 3.2 μm, the thickness of the core layer 3 is 49.9 μm, the thickness of the second surface layer 4 is 3.0 μm, and the thickness of the second surface layer 5 is 1.8 μm.

[0090] Example 5

[0091] This embodiment provides an anti-counterfeiting cavitation label film with low interlayer bonding force. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a glossy layer, and the second surface layer 5 is a glossy layer. Specifically, the formula of each layer is as follows:

[0092] The first surface layer 1 comprises: 95 wt% homopolypropylene and 5 wt% anti-blocking masterbatch;

[0093] First surface layer 2: 25wt% copolymerized polypropylene and 75wt% inorganic matte masterbatch;

[0094] Core layer 3: 87.5wt% homopolypropylene, 10.0wt% pearlescent masterbatch and 2.5wt% white masterbatch;

[0095] Second surface layer 4: 90 wt% homopolypropylene and 10 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity is 0.5 dL / g, and the content of 5-norbornene-2-methanol is 5 mol%);

[0096] Second surface layer 5: 95 wt% homopolypropylene and 5 wt% anti-blocking masterbatch.

[0097] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is basically the same as that in Example 1, except that: the melt extrusion temperature of the first surface layer 1 is 230-260°C; the melt extrusion temperature of the first surface layer 2 is 200-260°C; the melt extrusion temperature of the second surface layer 5 is 230-260°C; the temperature of the longitudinal stretching zone of the first surface layer 1 is 100-135°C; the temperature of the longitudinal stretching zone of the first surface layer 5 is 100-135°C.

[0098] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this embodiment is 68.2 μm, wherein the thickness of the first surface layer 1 is 1.7 μm, the thickness of the first surface layer 2 is 2.8 μm, the thickness of the core layer 3 is 59.8 μm, the thickness of the second surface layer 4 is 2.3 μm, and the thickness of the second surface layer 5 is 1.6 μm.

[0099] Comparative Example 1

[0100] This comparative example provides a cavitation label film. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a bright layer, and the second surface layer 5 is a matte layer. Specifically, the formula of each layer is as follows:

[0101] The first surface layer 1 comprises: 98 wt% copolymerized polypropylene and 2 wt% anti-blocking masterbatch;

[0102] First surface layer 2: 100wt% homopolymer polypropylene;

[0103] Core layer 3: 85.0wt% homopolypropylene, 13.0wt% pearlescent masterbatch and 2.0wt% white masterbatch;

[0104] Second surface layer 4: 100wt% homopolymer polypropylene;

[0105] Second surface layer 5: 50wt% copolymerized polypropylene and 50wt% low pressure high density polyethylene.

[0106] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is the same as that in Example 1.

[0107] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is 60.4 μm, wherein the thickness of the first surface layer 1 is 2.4 μm, the thickness of the first surface layer 2 is 4.5 μm, the thickness of the core layer 3 is 49.2 μm, the thickness of the second surface layer 4 is 2.6 μm, and the thickness of the second surface layer 5 is 1.7 μm.

[0108] Comparative Example 2

[0109] This comparative example provides a cavitation label film. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a bright layer, and the second surface layer 5 is a matte layer. Specifically, the formula of each layer is as follows:

[0110] The first surface layer 1 comprises: 98 wt% copolymerized polypropylene and 2 wt% anti-blocking masterbatch;

[0111] First surface layer 2: 100wt% homopolymer polypropylene;

[0112] Core layer 3: 85.5wt% homopolypropylene, 12.0wt% pearlescent masterbatch and 2.5wt% white masterbatch;

[0113] Second surface layer 4: 90 wt% homopolypropylene and 10 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity is 0.5 dL / g, and the content of 5-norbornene-2-methanol is 5 mol%);

[0114] Second surface layer 5: 50wt% copolymerized polypropylene and 50wt% low pressure high density polyethylene.

[0115] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is the same as that in Example 1.

[0116] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is 59.7 μm, wherein the thickness of the first surface layer 1 is 1.8 μm, the thickness of the first surface layer 2 is 2.0 μm, the thickness of the core layer is 51.7 μm, the thickness of the second surface layer 4 is 2.7 μm, and the thickness of the second surface layer 5 is 1.5 μm.

[0117] Comparative Example 3

[0118] This comparative example provides a cavitation label film. Figure 1, including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a glossy layer, and the second surface layer 5 is a glossy layer. Specifically, the formula of each layer is as follows:

[0119] The first surface layer 1 comprises: 98 wt% copolymerized polypropylene and 2 wt% anti-blocking masterbatch;

[0120] First surface layer 2: 30wt% homopolymer polypropylene and 70wt% inorganic matte masterbatch;

[0121] Core layer 3: 83.5wt% homopolypropylene, 15.0wt% pearlescent masterbatch and 1.5wt% white masterbatch;

[0122] Second surface layer 4: 100wt% homopolymer polypropylene;

[0123] Second surface layer 5: 95 wt% homopolypropylene and 5 wt% anti-blocking masterbatch.

[0124] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is basically the same as that in Example 1, except that: the melt extrusion temperature of the second surface layer 5 is 230-260°C; the temperature of the longitudinal stretching zone of the second surface layer 5 is 100-135°C.

[0125] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is 68.5 μm, wherein the thickness of the first surface layer 1 is 1.8 μm, the thickness of the first surface layer 2 is 2.0 μm, the thickness of the core layer 3 is 60.2 μm, the thickness of the second surface layer 4 is 3.0 μm, and the thickness of the second surface layer 5 is 1.5 μm.

[0126] Comparative Example 4

[0127] This comparative example provides a cavitation label film. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a glossy layer, and the second surface layer 5 is a glossy layer. Specifically, the formula of each layer is as follows:

[0128] The first surface layer 1 comprises: 98 wt% copolymerized polypropylene and 2 wt% anti-blocking masterbatch;

[0129] First surface layer 2: 30wt% homopolymer polypropylene and 70wt% inorganic matte masterbatch;

[0130] Core layer 3: 85.0wt% homopolypropylene, 13.0wt% pearlescent masterbatch and 2.0wt% white masterbatch;

[0131] Second surface layer 4: 80 wt% homopolypropylene and 20 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity is 0.5 dL / g, and the content of 5-norbornene-2-methanol is 5 mol%);

[0132] Second surface layer 5: 98 wt% homopolypropylene and 2 wt% anti-blocking masterbatch.

[0133] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is basically the same as that in Example 1, except that: the melt extrusion temperature of the second surface layer 5 is 230-260°C; the temperature of the longitudinal stretching zone of the second surface layer 5 is 100-135°C.

[0134] However, during the production process, the production was not smooth and stratification occurred.

[0135] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is 68.5 μm, wherein the thickness of the first surface layer 1 is 1.8 μm, the thickness of the first surface layer 2 is 2.0 μm, the thickness of the core layer 3 is 60.2 μm, the thickness of the second surface layer 4 is 3.0 μm, and the thickness of the second surface layer 5 is 1.5 μm.

[0136] Comparative Example 5

[0137] This comparative example provides a cavitation label film. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a glossy layer, and the second surface layer 5 is a glossy layer. Specifically, the formula of each layer is as follows:

[0138] The first surface layer 1 comprises: 98 wt% homopolypropylene and 2 wt% anti-blocking masterbatch;

[0139] First surface layer 2: 25wt% homopolymer polypropylene and 75wt% inorganic matte masterbatch;

[0140] Core layer 3: 86.5wt% homopolypropylene, 10.0wt% pearlescent masterbatch and 3.5wt% white masterbatch;

[0141] Second surface layer 4: 90 wt% homopolypropylene and 10 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity is 0.5 dL / g, and the content of 5-norbornene-2-methanol is 15 mol%);

[0142] Second surface layer 5: 96 wt% homopolypropylene and 4 wt% anti-blocking masterbatch.

[0143] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is basically the same as that in Example 1, except that: the melt extrusion temperature of the first surface layer 1 is 230-260°C; the melt extrusion temperature of the second surface layer 5 is 230-260°C; the temperature of the longitudinal stretching zone of the first surface layer 1 is 100-135°C; the temperature of the longitudinal stretching zone of the second surface layer 5 is 100-135°C.

[0144] However, during the production process, the production was not smooth and stratification occurred.

[0145] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is 68.5 μm, wherein the thickness of the first surface layer 1 is 1.8 μm, the thickness of the first surface layer 2 is 2.0 μm, the thickness of the core layer 3 is 60.2 μm, the thickness of the second surface layer 4 is 3.0 μm, and the thickness of the second surface layer 5 is 1.5 μm.

[0146] Comparative Example 6

[0147] This comparative example provides a cavitation label film. Figure 1 , including a first surface layer 1, a first surface layer 2, a core layer 3, a second surface layer 4 and a second surface layer 5 arranged in sequence, wherein the surface of the first surface layer 1 is a printing surface, the first surface layer 1 is a glossy layer, and the second surface layer 5 is a matte layer. Specifically, the formula of each layer is as follows:

[0148] The first surface layer 1 comprises: 98 wt% copolymerized polypropylene and 2 wt% anti-blocking masterbatch;

[0149] First surface layer 2: 65wt% homopolymer polypropylene and 35wt% inorganic matte masterbatch;

[0150] Core layer 3: 85.5wt% homopolypropylene, 12.0wt% pearlescent masterbatch and 2.5wt% white masterbatch;

[0151] Second surface layer 4: 90 wt% homopolypropylene and 10 wt% ethylene-5-norbornene-2-methanol copolymer (intrinsic viscosity 0.5 dL / g, 5-norbornene-2-methanol content 0.5 mol%;

[0152] Second surface layer 5: 50wt% copolymerized polypropylene and 50wt% low pressure high density polyethylene.

[0153] The preparation method of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is the same as that in Example 1.

[0154] However, during the production process, the production was not smooth and stratification occurred.

[0155] The total thickness of the anti-counterfeiting cavitation label film with low interlayer bonding force in this comparative example is 60.3 μm, wherein the thickness of the first surface layer 1 is 1.8 μm, the thickness of the first surface layer 2 is 2.0 μm, the thickness of the core layer 3 is 51.5 μm, the thickness of the second surface layer 4 is 3.0 μm, and the thickness of the second surface layer 5 is 2.0 μm.

[0156] Performance Testing

[0157] The following performance tests were performed on the films of Examples 1-5 and Comparative Examples 1-6 respectively:

[0158] Thickness: measured according to GB / T 6672-2001;

[0159] Tensile strength and nominal strain at break: measured according to GB / T 1040.3;

[0160] Density: Determined according to GB / T 10003-2008;

[0161] Delamination test: Stick 3M 810 tape on the printed surface (surface of the first surface layer 1), use a 2kg roller to roll back and forth on the tape 6 times without applying external force (meaning that no additional force is applied to the film except the weight of the roller itself), make sure there are no bubbles between the tape and the film, and finally pull up the tape at a 60-degree angle to observe the film delamination phenomenon.

[0162] Delamination effect evaluation: Excellent, meaning that the core layer of the film can be separated from both the first surface layer and the second surface layer in the delamination test; Average, meaning that the core layer of the film can only be separated from one of the first surface layer and the second surface layer in the delamination test; No delamination, meaning that no stratification occurs in the film in the delamination test.

[0163] The above test results are summarized in Table 1:

[0164] Table 1 Film performance test results

[0165]

[0166] Please refer to Table 1. The anti-counterfeiting cavitation label film with low interlayer bonding force of the present invention has good release effect and can be used as a substrate to make labels, thereby improving the anti-counterfeiting ability of the labels and playing a role of double anti-counterfeiting insurance.

[0167] In the film of Comparative Example 1, the first surface layer and the second surface layer are both composed of homopolymer polypropylene, and the total thickness of the first surface layer and the first surface layer accounts for too high a proportion of the thickness of the entire film. The film of Comparative Example 1 is not prone to interlayer separation, that is, it does not delaminate, and the anti-counterfeiting effect is poor.

[0168] The first surface layer of the film of Comparative Example 2 is composed of homopolymer polypropylene; the second surface layer of the film of Comparative Example 3 is composed of homopolymer polypropylene; the films of Comparative Examples 2-3 have average release effects and average anti-counterfeiting effects compared with the anti-counterfeiting cavitating label film with low interlayer bonding force of the present invention.

[0169] In the film of Comparative Example 4, the content of ethylene-5-norbornene-2-methanol copolymer in the second surface layer is too high, which is not conducive to smooth production, delamination is prone to occur during stretching, and the film fracture strain is low; in the film of Comparative Example 5, the first surface layer is composed of homopolypropylene, which improves the strength of the film, but the content of 5-norbornene-2-methanol in the ethylene-5-norbornene-2-methanol copolymer in the second surface layer is too high, which is not conducive to smooth production, delamination is prone to occur during stretching, and the film fracture strain is low; in the film of Comparative Example 6, the content of 5-norbornene-2-methanol in the ethylene-5-norbornene-2-methanol copolymer in the second surface layer is too low, which results in excessively high bonding force between the core layer and the second surface layer, which is not conducive to delamination.

[0170] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. An anti-counterfeiting cavitation label film with low interlayer bonding force, characterized in that: It comprises a first surface layer, a first surface layer, a core layer, a second surface layer and a second surface layer which are arranged in sequence; the first surface layer comprises polypropylene and 60-75wt% of an inorganic matte masterbatch, the inorganic matte masterbatch comprises polypropylene and 25-50wt% of calcium carbonate or silicon dioxide, and the particle size D50 of the calcium carbonate or the silicon dioxide in the inorganic matte masterbatch is 0.5-1μm; the core layer comprises polypropylene and a pearlescent masterbatch; the second surface layer comprises polypropylene and 9-12wt% of an ethylene-5-norbornene-2-methanol copolymer, and the content of 5-norbornene-2-methanol in the ethylene-5-norbornene-2-methanol copolymer is 3-6mol%.

2. The anti-counterfeiting cavitation label film with low interlayer bonding force according to claim 1, characterized in that: In the second surface layer, the intrinsic viscosity of the ethylene-5-norbornene-2-methanol copolymer is 0.2-1 dL / g.

3. The anti-counterfeiting cavitation label film with low interlayer bonding force according to claim 1, characterized in that: The content of the pearlescent masterbatch in the core layer is 3-15wt%; the pearlescent masterbatch comprises polypropylene and 50-80wt% of a polymer or calcium carbonate, wherein the polymer is a polymer incompatible with polypropylene, and the particle size D50 of the calcium carbonate in the pearlescent masterbatch is 1.0-1.5μm.

4. The anti-counterfeiting cavitation label film with low interlayer bonding force according to claim 1, characterized in that: The core layer further comprises 1-5wt% of white masterbatch; the white masterbatch comprises polypropylene and 50-70wt% of titanium dioxide.

5. The anti-counterfeiting cavitation label film with low interlayer bonding force according to claim 4, characterized in that: The particle size D50 of the titanium dioxide in the white masterbatch is 400-800 nm.

6. The anti-counterfeiting cavitation label film with low interlayer bonding force according to claim 1, characterized in that: The first surface layer is a bright layer or a matte layer; when the first surface layer is a bright layer, the first surface layer comprises 90-100wt% polypropylene and 0-10wt% anti-blocking masterbatch; when the first surface layer is a matte layer, the first surface layer comprises 90-100wt% matte masterbatch and 0-10wt% anti-blocking masterbatch.

7. The anti-counterfeiting cavitation label film with low interlayer bonding force according to claim 1, characterized in that: The second surface layer is a bright layer or a matte layer; when the second surface layer is a bright layer, the second surface layer comprises 90-100wt% polypropylene and 0-10wt% anti-blocking masterbatch; when the second surface layer is a matte layer, the second surface layer comprises 90-100wt% matte masterbatch and 0-10wt% anti-blocking masterbatch.

8. The anti-counterfeiting cavitation label film with low interlayer bonding force according to claim 1, characterized in that: The total thickness of the film is 35-70μm and the apparent density is 0.55-0.80g / cm 3 ; The thickness of the first surface layer and the second surface layer are 1.5-5.0 μm respectively; the thickness of the first surface layer and the second surface layer are 1.5-3.5 μm respectively; the total thickness of the first surface layer and the first surface layer is 3.0-10.0% of the total thickness of the entire film.

9. A method for preparing an anti-counterfeiting cavitation label film with low interlayer bonding force according to any one of claims 1 to 8, characterized in that: The following steps are involved: The raw materials of each layer are added to each extruder to form a homogenized melt, and the melt is filtered and then co-extruded through a die head in multiple layers; Then, according to the flat film method, the cast sheet is quenched into a thick sheet, and the thick sheet is made into a biaxially stretched film by a method of first longitudinally and then transversely or longitudinally and transversely simultaneously biaxially stretching; or according to the tubular film method, the melt is separated from the mold to form a primary tubular film, which is then quenched and then transversely inflated and longitudinally stretched to form a biaxially stretched film; After cooling, the film is subjected to corona treatment, flame treatment or plasma treatment, and then rolled into a mother roll. After the mother roll is subjected to aging treatment, it is slit into finished products.

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