Highly printable ink receptive and low haze low density label films, methods of making and use thereof

Abstract

The present application belongs to the technical field of shrink film processing, and particularly relates to a label film with strong printing ink adaptability, low haze and low density, a preparation method and application thereof. The modified resin material is obtained through grafting reaction of acrylic acid and epoxy resin, and then is blended and granulated with cyclic olefin polymer to obtain a modified surface film layer base material. Finally, the label film with a density less than 0.96 g / cm<3> is prepared through improvement of subsequent three-layer co-extrusion process conditions, so that it can float on the surface of water after being crushed, and is separated from other components by flotation due to the density difference. Meanwhile, the label film obtained by the present application has strong printing ink adaptability and low haze, and can significantly improve the adhesion effect and stability of ink on the surface thereof. In addition, the label film obtained by the present application has good opening property. 3 ​

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of shrink film processing, and particularly relates to a label film with strong printing ink adaptability, low haze and low density and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of the packaging industry, label films, as a key component of food, daily necessities and other commodity packaging, are increasingly widely used. Label films are usually used for shrink sleeve labeling, full-seal labeling, bottle cap and bottle cap sealing, etc. Compared with traditional label materials, label films, especially heat-shrinkable label films, have the advantages of good adhesion, high transparency, good gloss, high strength, etc., which can greatly improve the visual effect and shelf appeal of the packaging. At present, the mainstream heat-shrinkable label film materials on the market include polyvinyl chloride (PVC), polyethylene terephthalate-1,4-cyclohexane dimethanol (PETG) and oriented polystyrene (OPS). Among them, PVC film has a serious environmental defect that it may produce harmful substances dioxin in the recycling process, and its application is strictly limited and gradually replaced. OPS film has the advantages of high strength, good printing performance and low cost; PETG film is excellent in non-toxicity, high shrinkage rate, mechanical and optical properties. Therefore, the use of OPS and PETG films is rapidly increasing.

[0003] However, the existing OPS and PETG label film technologies still have two significant defects in terms of sustainability and application performance. First, recycling separation is difficult, affecting the circular economy: In the recycling process of polyethylene terephthalate (PET) bottles and other containers, the water flotation method is usually used to separate the bottle body (PET material) from the label film. Ideally, PET bottle pieces (density greater than water) should sink, and label film materials (density should be less than water) should float, thereby achieving effective separation. However, the densities of OPS and PETG materials are both greater than water, causing them to sink to the bottom of the water along with the PET bottle pieces during the flotation process, making separation difficult. If OPS or PETG is mixed into the recycled PET material, it will seriously contaminate the recycled material stream, causing its reprocessing performance to deteriorate and making it unable to be used to manufacture new PET bottles, greatly hindering the closed-loop recycling of plastic packaging. Second, the ink adhesion and film opening performance are not good, affecting the printing quality and processing efficiency: First, the surface properties of existing label film materials need to be optimized, resulting in insufficient ink adhesion and long-term stability on them, affecting the quality and durability of the printed pattern. Second, to prevent the film from sticking together during winding and storage, an opening agent is usually added to the film material. The commonly used inorganic silica opening agent has the following disadvantages: particles are prone to agglomeration, causing defects such as "fish eyes" and scratches on the film surface, and may clog the filter screen of the extruder; at the same time, inorganic particles can significantly increase the haze of the film, damaging its transparency. If no opening agent is added, the film may stick together due to a large coefficient of friction. Therefore, the industry urgently needs an improved solution that can effectively balance the opening performance and optical performance of the film.

[0004] In summary, developing a new type of label film that is easy to recycle and separate (especially from PET bottles), while having excellent ink adhesion and ideal opening performance, has become a technical problem that needs to be solved in the field. In view of this, the present invention is proposed. SUMMARY

[0005] The present invention aims to at least partially solve one of the problems of the prior art. To this end, the present invention provides a strong printing ink adaptability and low haze and low density label film, as well as a preparation method and application thereof.

[0006] The technical solutions provided by the present invention are as follows:

[0007] In a first aspect, the present invention provides a strong printing ink adaptability and low haze and low density label film, which is formed in an ABA three-layer structure by three-layer co-extrusion. The material of the A layer structure comprises at least 99% of a modified cycloolefin polymer, which is prepared by blending and granulating an epoxy resin-acrylic composite modified resin and a cycloolefin polymer. The material of the B layer structure is selected from at least one of a cycloolefin copolymer, polypropylene, polyethylene, and a polyolefin polymer containing less than 10% butene.

[0008] Preferably, the epoxy-acrylic composite modified resin is prepared by grafting reaction of an epoxy resin solution, a monomer mixture and an initiator at a temperature of 100-120°C; the monomer mixture contains at least 5% of acrylic monomers.

[0009] Preferably, the modified cycloolefin polymer is COC or COP.

[0010] Preferably, the material of the A layer structure contains 100% of the modified cycloolefin polymer.

[0011] Preferably, the cycloolefin copolymer accounts for 0-30% of the material of the B layer structure.

[0012] Preferably, the polypropylene accounts for 0-80% of the material of the B layer structure.

[0013] Preferably, the polyethylene accounts for 0-50% of the material of the B layer structure.

[0014] Preferably, the polyolefin polymer containing less than 10% of butene accounts for 0-50% of the material of the B layer structure.

[0015] Preferably, the material of the B layer structure contains 70-90% of polypropylene and 10-30% of linear low-density polyethylene. Preferably, for the label film of the present application, the label film is coated with ink, a tape is attached to the side of the label film coated with ink, and then the tape and the label film are separated by a tension machine, the ink drop area on the separated label film is counted, and the ink drop ratio is less than 10%.

[0016] Preferably, for the label film of the present application, the proportion of the number of film surface crystal points with a size greater than 0.5 and ≤1 to the total number of all film surface crystal points is >60%.

[0017] In the second aspect, the present application provides a preparation method of the label film with strong printing ink adaptability and low haze and low density, which comprises the following steps: mixing and melt-plasticizing B layer core film layer material and A layer surface film layer material, and then forming an ABA three-layer structure by three-layer co-extrusion; wherein the material of the A layer structure contains 100% of a modified cycloolefin polymer, the modified cycloolefin polymer is prepared by blending and granulating an epoxy-acrylic composite modified resin and a cycloolefin polymer; the material of the B layer structure is selected from at least one of a cycloolefin copolymer, polypropylene, polyethylene and a polyolefin polymer containing less than 10% of butene.

[0018] Preferably, the filter extrusion temperature of the core film layer material is 230-260°C, the filter extrusion temperature of the surface film layer material is 230-260°C, and the rotation speed of the screw is 100-200 rpm.

[0019] Preferably, the B layer core film layer material and the A layer surface film layer material are sequentially subjected to the steps of feeding mixing, melt plasticizing, filtering extruding, casting sheet, longitudinal stretching, transverse stretching, edge cutting and winding; wherein the preheating temperature in the longitudinal stretching is 90±2℃, the longitudinal stretching temperature is 81±2℃, the longitudinal stretching ratio is 1.12±0.01, the longitudinal stretching setting temperature is 85±2℃, and the setting time is 3±1 seconds; the preheating temperature in the transverse stretching is 110±2℃, the transverse stretching temperature is 90±2℃, the transverse stretching ratio is 4.8±0.1, the transverse stretching setting temperature is 70±2℃, and the transverse stretching setting time is 8±1 seconds.

[0020] In a third aspect, the application provides the application of the label film with strong printing ink adaptability and low haze and low density or the label film prepared by the preparation method in product packaging.

[0021] Advantages

[0022] The application provides a label film with strong printing ink adaptability and low haze and low density and a preparation method and application thereof. 3 The label film prepared by the method has a density of less than 0.96 g / cm Specific embodiments

[0023] The application provides a label film with strong printing ink adaptability and low haze and low density and a preparation method and application thereof.

[0024] In the specific embodiments and the following examples, the label film with strong printing ink adaptability and low haze and low density is prepared by the following steps.

[0025] (1) Pretreatment: epoxy resin (E-51) is dissolved in xylene (solid content 60%); monomers (MMA, BA, AA) are excluded from the polymerization inhibitor.

[0026] (2) Grafting reaction: Add epoxy resin solution to the flask, heat to 110°C, and drop "monomer mixture + initiator (BPO)" (5% AA in monomer, providing carboxyl group to react with epoxy group; BPO dosage 1.0%) dropwise for 2-3h.

[0027] (3) Insulation: Continue to react for 2-3h at 100-120°C to make epoxy group of epoxy resin and carboxyl group of AA fully react (ester bond is formed), and monomers are grafted to the epoxy backbone through free radicals.

[0028] (4) Post-processing: After cooling, add triethylamine to neutralize residual carboxyl group (pH adjusted to 7-8), and adjust the solid content of the solvent to 60% to obtain an epoxy resin-acrylic composite modified resin (used as a surface modifier).

[0029] (5) The obtained epoxy resin-acrylic composite modified resin and cycloolefin polymer are blended and granulated using a twin-screw extruder, and a modified cycloolefin polymer is obtained. The epoxy resin-acrylic composite modified resin accounts for 3-8%, and the temperature of the twin-screw extruder is set to 200-250°C.

[0030] (6) The modified cycloolefin polymer obtained in step (5) is added to extruder 1, and the modified polyolefin mixture is added to extruder 2 for melt plasticization. Both extruders 1 and 2 are twin-screw extruders, and their processing temperatures are maintained at 230-260°C.

[0031] (7) The raw materials in step (6) are dispersed through an adapter, combined in a die, and extruded to a chill roll for casting.

[0032] (8) The melt castings in step (7) are subjected to longitudinal and transverse stretching, respectively, and are drawn and wound to obtain a low-density label film with a structure of ABA three layers, usually with a thickness of 20-100μm, and the A layer accounts for 10%-50% of the total layer thickness.

[0033] Further, the components of the cycloolefin polymer in the present application can be COC or COP.

[0034] Further, the attachment method of the castings in the present application can use one or both of calendering or air knife coating.

[0035] Further, the raw materials in extruder 1 in the present application are used in the two A layers of the label film, and the raw materials in extruder 2 are used in the B layer.

[0036] Further, the A layer material in the present application is made of 100% cycloolefin polymer, and no opening agent is added.

[0037] Further, the B layer modified polyolefin component in the present application includes 0-30% cyclic olefin copolymer, 0-80% polypropylene, 0-50% polyethylene and 0-50% polyolefin polymer containing less than 10% butene.

[0038] Further, the strong printing ink adaptability and low haze low density label film in the present application is surface opening modified by special process of the extruder, and by virtue of the special structure of the cyclic olefin, the system automatically increases the speed ratio of the extruder by 0.5 every half an hour during the processing, until 2.0 is added, and then decreases by 0.5 every half an hour, until 2.0 is reduced. The screw shear speed is changed all the time, while the extrusion amount is kept constant, so that the cyclic olefin polymer can generate uniform and stable small crystal points in the extruder, which are distributed on the surface of the film to play the role of opening.

[0039] Further, the scheme in the present application controls the growth speed of the crystal points by keeping the speed of the screw within the range of 100-200 rpm, so that better film properties are obtained.

[0040] Further, the density of the strong printing ink adaptability and low haze low density label film finally prepared in the present application is less than 0.96 g / cm 3 .

[0041] In summary, the strong printing ink adaptability and low haze low density label film is prepared by modifying the surface raw material and improving the process through the modified acrylic resin. The density of the heat shrinkable film is controlled to be less than 0.96 g / cm 3 , so that it can float on the surface of water after being crushed, and the flotation separation is realized due to the density difference between the other components. The separation process is simple and efficient, and is suitable for large-scale recycling procedures. The strong printing ink adaptability and low haze low density label film is prepared after the surface modification by the surface modifier, which can significantly improve the adhesion effect and stability of the ink on the surface, and the ink fastness test method is efficient and accurate. The technical scheme provided by the present application avoids the addition of inorganic opening agent silicon dioxide, reduces the haze of the film, and the surface opening modification component is more uniformly distributed, and the film properties are better.

[0042] The test of the ink adhesion effect in the prior art usually uses a standard width of 3M tape to stick and then peel off, which cannot determine the difference in the ink adhesion effect of the two ways of ink falling. In a more specific embodiment, the ink adhesion effect of the label film is determined by the following method.

[0043] The method for determining the ink adhesion effect of the label film of the present application comprises the following steps:

[0044] (1) Respectively select the concave printing red ink of polyurethane and acrylic system, use the ink scraping stick to evenly spread on the film surface, after the solvent volatilizes completely, respectively select 10cm*10cm small square sample.

[0045] (2) Take 10cm*10cm transparent tape to paste the printed label film full coverage, and then select 5kg / 10cm*10cm sample to press for 5min.

[0046] (3) Take three pieces of each sample, and carry out tensile testing machine stretching (the upper clamp of the tensile testing machine clamps the adhesive tape, and the lower clamp clamps the printed ink label), until the adhesive tape and the film are completely separated.

[0047] (4) Place the label on the coordinate paper to count the ink dropping area, and then calculate the average value.

[0048] (5) Count and calculate the ink dropping ratio, and the calculation formula is: ink dropping ratio=ink dropping area / 100.

[0049] Determination shows that the ink dropping ratio of the label film is less than 10%, and the ink adhesion effect of the label film is good.

[0050] The crystal point generation and distribution of the conventional label film in the production process are generally not controlled. The processing technology provided by the application makes the cycloolefin polymer itself generate crystal points, and the crystal points are uniformly distributed on the film surface, which can replace the generation of the traditional opening master batch. In a more specific embodiment, the application adopts the following method to test the uniformity of the distribution of the crystal points.

[0051] The method for testing the uniformity of the distribution of the crystal points comprises the following steps:

[0052] (1) Select a 0.001*0.001m sample film every 1-5m, and a total of 9 pieces.

[0053] (2) Measure the size of the marked particles and count the number under the electron microscope, and the crystal points include multiple crystal points with the size less than 0.3um, 0.3≤crystal point size≥0.5, 0.5<crystal point size≥1, 1<crystal point size≥2 and crystal point size>2um.

[0054] (3) Make the percentage of the particle size and the number of particles.

[0055] Determination shows that for the label film provided by the application, the number of crystal points with a specific size (0.5<crystal point size≥1) / total number of crystal points on the film surface>60%, and the uniformity of the distribution of the crystal points of the label film is good.

[0056] The application will be described with reference to the embodiments described below. It should be pointed out that these embodiments are only descriptive and do not limit the application in any way. All other embodiments obtained by those skilled in the art on the basis of the embodiments described in the application without creative labor are within the scope of the application.

[0057] The endpoints of the ranges and any values disclosed in the specification are not limited to the precise values stated. The ranges or values should be construed to be approximations that allow for significant variation. Various ranges of values that are stated in the specification as being desired, or, alternatively, preferred, to achieve successful results should be considered to include any and all values falling within the range, including the values which are adjacent or intermediate to or one or more values which are subsumed in the ranges. It is intended to claim by way of disclosure each and every sub-combination of the disclosed elements, whether specifically disclosed or not.

[0058] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", or "some specific embodiments" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0059] The materials, reagents and the like used in the following examples can be obtained from commercial channels unless otherwise specified. The experimental methods in the examples not specified in the specific conditions are usually carried out according to the conventional conditions or according to the conditions recommended by the manufacturer.

[0060] Example 1

[0061] The present embodiment provides a floating heat shrinkable label film with strong printing ink adaptability and low haze and low density, and the preparation method is as follows:

[0062] (I) Preparation of surface modifier:

[0063] (1) Pretreatment: 3000g of epoxy resin (E-51) is dissolved in 2326mL of dimethylbenzene to obtain an epoxy resin solution with a solid content of 60%; MMA, BA and AA monomers are prepared, and the monomers are treated with a polymerization inhibitor. After the monomer is treated with a polymerization inhibitor, the amount of AA is 150g, the amount of BA is 1995g, and the amount of MMA is 855g.

[0064] (2) Grafting reaction: 4762 mL of epoxy resin solution was added to a flask, and the temperature was raised to 110°C. 5000 mL of "monomer mixture + initiator (BPO)" was added dropwise, and the dropping was completed in 2.5 h. The monomer mixture was composed of 150 g of AA, 1995 g of MMA, 855 g of BA, and 1744 mL of xylene solvent (solvent type). The proportion of AA in the monomer mixture was 5%, providing carboxyl groups for reaction with epoxy groups. The amount of BPO was 30 g, accounting for 1.0% of the total amount of monomers.

[0065] (3) Heat preservation: continue to react at 110°C for 2.5 h to make the epoxy groups of the epoxy resin fully react with the carboxyl groups of AA (ester bond is formed), and at the same time, the monomers are grafted to the epoxy backbone through free radicals.

[0066] (4) Post-treatment: After cooling to room temperature, add triethylamine to neutralize the residual carboxyl groups (pH adjusted to 8) to obtain an epoxy resin-acrylic composite modified resin with a solid content of 60%.

[0067] (5) The obtained epoxy resin-acrylic composite modified resin and cycloolefin polymer (COC) are blended and granulated using a twin-screw extruder to obtain a modified cycloolefin polymer (modified COC). The proportion of epoxy resin-acrylic composite modified resin is 5%, and the mass ratio of cycloolefin polymer is 95%. The temperature of the twin-screw extruder is set to 230°C.

[0068] (II) Preparation of a floatable heat shrinkable film:

[0069] (1) The core film layer material and the surface film layer material are respectively fed, mixed, melted and plasticized, and filtered and extruded through a three-layer co-extrusion biaxial stretching production process, and then the heat shrinkable film is obtained after casting, longitudinal stretching, transverse stretching, edge cutting and winding.

[0070] (2) The surface film layer material includes 100 parts of the modified COC described above by weight; the core film layer material includes 80 parts of PP and 20 parts of LLDPE.

[0071] (3) The filtration extrusion temperature of the core film layer material is 240°C, and the filtration extrusion temperature of the surface film layer material is 260°C. The screw rotation speed is 150 rpm. During the processing process of the auxiliary extruder, the rotation speed ratio of the extruder is automatically increased by 0.5 every hour, until it is increased to 2.0, and then it is decreased by 0.5 every half hour, until it is decreased to 2.0.

[0072] (4) The preheating temperature in the longitudinal stretching is 90°C, the longitudinal stretching temperature is 81°C, the longitudinal stretching ratio is 1.12, the longitudinal stretching setting temperature is 85°C, and the setting time is 3 seconds and a half.

[0073] (5) The preheating temperature in the transverse stretching is 110°C, the transverse stretching temperature is 90°C, the transverse stretching ratio is 4.8 times, the transverse stretching setting temperature is 70°C, and the transverse stretching setting time is 8 seconds.

[0074] (6) The prepared floatable heat-shrinkable film is a three-layer composite structure with a layer thickness of 40 μm, wherein the surface film layer has a thickness of 8 μm, the longitudinal shrinkage rate is 2%, and the transverse shrinkage rate is 70%.

[0075] Example 2

[0076] This example is the same as Example 1, except that in the step (5) of the first part, the cyclic olefin polymer COP is used.

[0077] Example 3

[0078] This example is the same as Example 1, except that in the step (3) of the first part, the holding temperature is 100°C; and in the step (2) of the second part, the core film layer material comprises 60 parts of PP, 25 parts of a polyolefin polymer containing 6% butene, and 15 parts of LLDPE.

[0079] Comparative Example 1

[0080] This comparative example provides a label film, and the preparation method thereof is the same as that of Example 1, except for the preparation steps of the floatable heat-shrinkable film, which are as follows:

[0081] (1) The core film layer material and the surface film layer material are respectively fed, mixed, melted and plasticized, and filtered and extruded through a three-layer co-extrusion biaxial stretching production process, and then the heat-shrinkable film is prepared after casting, longitudinal stretching, transverse stretching, edge cutting and winding.

[0082] (2) The surface film layer material comprises 98 parts of COC and 2 parts of silicon dioxide by weight; and the core film layer material comprises 80 parts of PP and 20 parts of LLDPE.

[0083] (3) The filtering extrusion temperature of the core film layer material is 240°C, and the filtering extrusion temperature of the surface film layer material is 260°C, and the screw rotation speed is 150 rpm.

[0084] (4) The preheating temperature in the longitudinal stretching is 90°C, the longitudinal stretching temperature is 81°C, the longitudinal stretching ratio is 1.12, the longitudinal stretching setting temperature is 85°C, and the setting time is 3 seconds and a half.

[0085] (5) The preheating temperature in the transverse stretching is 110°C, the transverse stretching temperature is 90°C, the transverse stretching ratio is 4.8 times, the transverse stretching setting temperature is 70°C, and the transverse stretching setting time is 8 seconds.

[0086] (6) The prepared floatable heat-shrinkable film has a three-layer composite structure, with a layer thickness of 40 μm, wherein the surface film layer has a thickness of 8 μm, a longitudinal shrinkage rate of 2%, and a transverse shrinkage rate of 70%.

[0087] Experimental Example 1

[0088] In this experimental example, the floatable heat-shrinkable film prepared in Example 1 is used as the test material, and the properties of the test material are detected.

[0089] (I) Test of uniformity of crystal point distribution:

[0090] (1) Every 1 m, select a 0.001 x 0.001 m sample film, a total of 9 pieces.

[0091] (2) Place the sample film under a microscope for small crystal point classification and counting.

[0092] The test results are shown in Table 1.

[0093]

[0094] (II) Test of printing fastness of ink:

[0095] (1) Select polyurethane and acrylic system gravure red ink respectively, and evenly apply them on the surface of the film using a squeegee. After the solvent is completely volatilized, select 10 cm x 10 cm small square samples.

[0096] (2) Use 10 cm x 10 cm transparent tape to paste the printed label film completely, and then select 5 kg per piece of 10 cm x 10 cm sample for pressing for 5 min.

[0097] (3) Then, each of the three samples is stretched by a tensile testing machine (the upper clamp clamps the tape, and the lower clamp clamps the printed label), until the tape and the film are completely separated. (4) Place the label on the coordinate paper to count the ink loss area, calculate the ink loss area ratio, and obtain the average value.

[0098] The test results are shown in Table 2.

[0099]

[0100] Referring to the above method, the label film prepared in Comparative Example 1 is used as the test material, and the properties of the test material are detected. The results are shown in Table 3.

[0101]

[0102] (III) Test of haze:

[0103] The haze tester of BYK is used to test according to the test method of ASTM D 1003.

[0104] The haze value of the label film obtained in Example 1 was 2.8.

[0105] The haze value of the label film obtained in Comparative Example 1 was 5.8.

[0106] Finally, it should be noted that the above examples are only the preferred embodiments of the present application, which are used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application; therefore, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A label film with strong adaptability to printing inks and low haze and low density, characterized in that, The label film is formed into an ABA three-layer structure through three-layer co-extrusion. The A-layer structure is made of 100% modified cyclic olefin polymer, which is obtained by blending and granulating an epoxy resin-acrylic composite modified resin and a cyclic olefin polymer. The epoxy resin-acrylic composite modified resin is obtained by grafting an epoxy resin solution, a monomer mixture, and an initiator at a temperature of 100-120°C. The monomer mixture contains at least 5% acrylic monomer. The B-layer structure is made of at least one of cyclic olefin copolymers, polypropylene, polyethylene, and polyolefin polymers containing less than 10% butene. The label film is coated with ink, specifically a polyurethane or acrylic gravure red ink. Adhesive tape is then pressed onto the ink-coated side of the label film, and a tensile testing machine is used to separate the tape and label film. The area of ​​ink loss on the separated label film is counted, and the ink loss rate is less than 10%. The proportion of film surface crystal points with a crystal point size greater than 0.5 μm and ≤ 1 μm is greater than 60% of the total number of film surface crystal points.

2. The label film with strong adaptability to printing inks and low haze and low density according to claim 1, characterized in that, Cyclic olefin polymers are composed of COC or COP.

3. The label film with strong adaptability to printing inks and low haze and low density according to claim 1, characterized in that, The proportion of cyclic olefin copolymers in the B-layer structure is 0-30%; Alternatively, polypropylene may comprise 0-80% of the material in the B-layer structure. Alternatively, polyethylene may comprise 0-50% of the material in the B-layer structure. Alternatively, the proportion of polyolefin polymers containing less than 10% butene in the B-layer structure material is 0-50%.

4. The label film with strong adaptability to printing inks and low haze and low density according to claim 3, characterized in that, The B-layer structure is composed of 80 parts by weight of polypropylene and 20 parts by weight of linear low-density polyethylene.

5. The method for preparing the label film with strong adaptability to printing inks and low haze and low density as described in any one of claims 1-4, characterized in that, The process includes the following steps: The core film material (B layer) and the surface film material (A layer) are fed, mixed, and melt-plasticized, and then a three-layer ABA structure is formed through co-extrusion. The A layer structure is made of 100% modified cyclic olefin polymer, which is obtained by blending and granulating epoxy resin-acrylic composite modified resin and the cyclic olefin polymer. During processing, the system automatically increases the extruder speed ratio by 0.5 every half hour until it reaches 2.0, then decreases it by 0.5 every half hour until it reaches 2.

0. The screw shear speed is maintained throughout the process, while the extrusion volume remains constant. The material of the B layer structure is selected from at least one of cyclic olefin copolymers, polypropylene, polyethylene, and polyolefin polymers containing less than 10% butene.

6. The application of the label film according to any one of claims 1-4 or the label film prepared by the preparation method according to claim 5 in product packaging.

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