Biaxially oriented polypropylene base film, preparation method thereof and adhesive tape film

Abstract

The invention relates to the field of films, in particular to a biaxially oriented polypropylene base film, a preparation method thereof and an adhesive tape film, the base film sequentially comprises a release functional layer, a core layer and a surface layer; the release functional layer comprises homo-polypropylene, 5-10 wt% of ethylene-propylene co-polypropylene and 20-30 wt% of a fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer, a fluorine-containing polysiloxane chain segment is formed by copolymerization connection of 3-4 fluorine-containing siloxane units, and an ethylene-norbornene chain segment is formed by copolymerization connection of 1-2 ethylene-norbornene units; the core layer comprises homo-polypropylene; the surface layer comprises ethylene-propylene co-polypropylene and 10 to 20 weight percent of PMMA (Polymethyl Methacrylate)-g-EVA (Ethylene The release force of the release functional layer can be reduced and the barrier property can be improved on the premise of ensuring the release uniformity, so that the prepared base film and the adhesive tape film are smoothly wound and unwound, the release force of the surface layer is improved, the adhesive force between the surface layer and the adhesive layer can be ensured without coating a bottom coating, and the production cost is reduced. And the adhesive tape film can be used in a high-humidity environment for a long time.

Description

Technical Field

[0001] The present invention relates to the field of films, in particular to a biaxially oriented polypropylene base film, a preparation method thereof, and an adhesive tape film. Background Art

[0002] Existing adhesive tape films generally include a substrate layer, a primer layer, and an adhesive layer from bottom to top. The substrate layer is usually a biaxially oriented polypropylene film (BOPP film) or a biaxially oriented polyester film (BOPET film) with a thickness of 12-20 μm. BOPP film has the characteristics of high transparency, good brightness, waterproofness, heat resistance, and low price, making it an ideal material for adhesive tape films.

[0003] In practical applications, tape films are typically rolled up and stored, with the adhesive layer applied to the other side of the substrate layer. However, due to the low surface energy of BOPP film and the strong polarity of the acrylate in the glue used to prepare the adhesive layer, the adhesive layer easily adheres to the other side of the substrate layer, resulting in the tape being unable to be unwound, the adhesive layer being separated from the primer layer, or the adhesive layer being separated from the substrate layer with the primer layer. Therefore, when using BOPP film as the substrate layer, it is generally necessary to coat the other side of the substrate layer with a material with lower surface energy, such as silicone oil, to facilitate separation of the other side of the substrate layer from the adhesive layer during use.

[0004] However, the inventors have found through extensive practice that the existing adhesive tape film still has the following defects after being coated with silicone oil: First, a coating process is required to cover the other side of the substrate layer with a silicone oil material with lower surface energy, which increases the production process and processing costs. It is difficult to ensure the uniformity of the coating during coating, and the silicone oil is prone to migration after coating, affecting the bonding strength between the adhesive layer and the primer layer; Second, the existing adhesive tape film usually has the problem of insufficient adhesion when exposed to a high-humidity environment for a long time; Third, the adhesion between the adhesive layer and the substrate layer of the existing adhesive tape film is insufficient, resulting in the adhesive layer detaching from the substrate layer when the tape film is unwound or the already pasted tape film is torn off for re-pasting and use, and the detached part of the adhesive layer needs to be cut off or a new tape film needs to be used for pasting. Summary of the Invention

[0005] Based on this, the object of the present invention is to provide a biaxially oriented polypropylene base film and a preparation method thereof. The biaxially oriented polypropylene base film of the present application, on the one hand, reduces the peeling force of the release functional layer by adding a certain amount of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer to the release functional layer while ensuring the compatibility of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer with homopolypropylene, and can achieve smooth winding and unwinding of the tape film and the biaxially oriented polypropylene base film without applying silicone oil; on the other hand, by adding polymethyl methacrylate grafted ethylene vinyl acetate copolymer (PMMA-g-EVA) to the surface layer, it is possible to ensure the adhesion between the surface layer and the adhesive layer without applying a primer layer on the surface layer, thereby enhancing the peeling force of the surface layer, which is beneficial to ensure that the adhesive layer of the prepared tape film will not separate from the surface layer when unwinding, and can be smoothly torn off for reuse after use. In addition, the addition of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer also improves the barrier properties of the release functional layer. Combined with the enhanced surface peeling force, it is beneficial for the tape film to maintain high adhesion in a high humidity environment, and can be used in a high humidity environment for a long time.

[0006] The technical solution of the present invention is achieved by the following methods:

[0007] A biaxially oriented polypropylene-based film comprises a release functional layer, a core layer, and a surface layer, which are sequentially arranged. The release functional layer comprises homopolypropylene, 5-10 wt% ethylene-propylene copolymerized polypropylene, and 20-30 wt% fluorinated polysiloxane-functionalized ethylene-norbornene block copolymer, wherein the fluorinated polysiloxane-functionalized ethylene-norbornene block copolymer is formed by copolymerizing a fluorinated polysiloxane segment and an ethylene-norbornene segment, wherein the fluorinated polysiloxane segment is formed by copolymerizing and connecting 3-4 fluorinated siloxane units, and the ethylene-norbornene segment is formed by copolymerizing and connecting 1-2 ethylene-norbornene units. The core layer comprises homopolypropylene, and the surface layer comprises ethylene-propylene copolymerized polypropylene and 10-20 wt% polymethyl methacrylate grafted ethylene vinyl acetate copolymer.

[0008] The biaxially oriented polypropylene base film described in the present invention and the biaxially oriented polypropylene base film of the present application, on the one hand, add a certain amount of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer and ethylene-propylene copolymerized polypropylene to the release functional layer, thereby reducing the peeling force of the release functional layer while ensuring the compatibility of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer with homopolypropylene, and achieving smooth winding and unwinding of the tape film and the biaxially oriented polypropylene base film without the need for coating silicone oil; on the other hand, by adding polymethyl methacrylate grafted ethylene vinyl acetate copolymer (PMMA-g-EVA) to the surface layer, the adhesion between the surface layer and the adhesive layer can be ensured without coating a primer layer on the surface layer, thereby enhancing the peeling force of the surface layer, which is beneficial to ensuring that the adhesive layer of the prepared tape film will not separate from the surface layer when unwinding, and can be smoothly torn off for reuse after use. In addition, the addition of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer also improves the barrier properties of the release functional layer. Combined with the enhanced surface peeling force, it is beneficial for the tape film to maintain high adhesion in a high humidity environment, and can be used in a high humidity environment for a long time.

[0009] The present application adds 20-30wt% of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer to the release functional layer and defines the composition of its molecular chain, thereby improving the release effect of the release functional layer while improving the barrier performance of the release functional layer. The tape film and the biaxially oriented polypropylene base film can be smoothly wound and unwound without the need for coating with silicone oil. The surface peeling force is enhanced, which is beneficial for the tape film to be used in a high-humidity environment for a long time and to maintain the adhesion between the adhesive layer and the substrate in a high-humidity environment. Specifically, if the content of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer is less than 20wt%, the release effect is not obvious, and it is not conducive to the smoothness of the winding and unwinding of the base film itself during the production process, and the surface peeling force is not significantly affected. It will also produce certain adverse effects; if the content of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer is higher than 30wt%, it will be detrimental to the effective co-extrusion of the release functional layer and the core layer, detrimental to the smoothness of biaxial stretching, and cracks will occur during production; if the number of ethylene-norbornene units in a single ethylene-norbornene segment is greater than 2, the rigidity of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer will be too large, which is not conducive to biaxial stretching; if the number of polysiloxane units in a single polysiloxane segment is greater than 4, the compatibility of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer with other components of the release functional layer may be poor, which is not conducive to the uniformity of the release effect and leads to poor final release effect.

[0010] On this basis, in order to ensure the compatibility of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer with the polypropylene in the release functional layer, the present application also adds 5-10 wt% of ethylene-propylene copolymerized polypropylene to the release functional layer to ensure that the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer can be evenly dispersed in the release functional layer.

[0011] On the other hand, the present application also adds 10-20wt% polymethyl methacrylate grafted ethylene vinyl acetate copolymer to the surface layer. The polymethyl methacrylate grafted ethylene vinyl acetate copolymer introduces amorphous polymethyl methacrylate (PMMA) through the graft polymerization process, disrupting the filling of the crystalline polyethylene segment and reducing the crystallinity, which is conducive to forming a smooth microstructure, giving it a high adhesion area, and increasing the content of polar ester groups, which is more conducive to improving the adhesion between the surface layer and the adhesive layer, so that the adhesive layer can be directly coated on the surface layer without applying a primer. In addition, the PMMA-g-EVA has shorter PMMA graft chains, which is conducive to forming a uniform interpenetrating polymer network at the interface between the surface layer and the adhesive layer, so that the surface layer and the adhesive layer are effectively increased in volume and have high adhesion, which is conducive to achieving the coating of the adhesive layer without applying a primer.

[0012] Furthermore, the melt index of the fluorinated polysiloxane-functionalized ethylene-norbornene block copolymer was measured at 190°C and 2.16 kg, ranging from 50 to 100 g / 10 min. Using a fluorinated polysiloxane-functionalized ethylene-norbornene block copolymer within this melt index range improves the required fluidity of the release layer, ensuring the proper adhesion between the longitudinal pull roller and the thick sheet during production.

[0013] Furthermore, the surface layer further comprises 0.5-1 wt% cross-linked polymethyl methacrylate particles. The cross-linked polymethyl methacrylate particles can be evenly dispersed in the surface layer. Adding cross-linked polymethyl methacrylate particles to the surface layer is beneficial to ensuring smooth winding and unwinding of the biaxially oriented polypropylene base film.

[0014] Furthermore, the content of polymethyl methacrylate in the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 20-40wt%; the number average molecular weight of the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 20,000-22,000 g / mol. This application also defines the content of PMMA in PMMA-g-EVA. If the PMMA content is greater than 40wt%, the viscosity of PMMA-g-EVA will be too high, and the compatibility with ethylene-propylene copolymer polypropylene will be poor, which is not conducive to obtaining thick sheets suitable for biaxial stretching, and there may be problems with roller sticking. If the PMMA content is less than 20wt%, it will not be possible to effectively form a uniform interpenetrating polymer network at the interface, which is not conducive to the adhesion between the surface layer and the adhesive layer. Within the specified number average molecular weight range, the polymethyl methacrylate grafted ethylene vinyl acetate copolymer has good melt matching with the ethylene-propylene copolymer polypropylene in the surface layer.

[0015] Furthermore, the melting point of the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 90-100° C. EVA generally has a low melting point and poor thermal stability. The melting point of the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 90-100° C., and it has better thermal stability than EVA.

[0016] Furthermore, the melting point of the ethylene vinyl acetate copolymer in the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 80-90° C., and the content of vinyl acetate in the ethylene vinyl acetate copolymer is 15-25 wt %, which is beneficial to maintaining the thermal stability of the polymethyl methacrylate grafted ethylene vinyl acetate copolymer and will not degrade at the processing temperature of the present invention.

[0017] Furthermore, the thickness of the release layer is 1-2 μm, the thickness of the surface layer is 1-2 μm, and the thickness of the biaxially oriented polypropylene base film is 12-25 μm. If the thickness of the release layer is greater than 2 μm, the haze of the biaxially oriented polypropylene base film will increase, which will increase production costs. If the thickness of the release layer is less than 1 μm, it will be difficult to achieve a good release effect, which is not conducive to unwinding the tape film in applications.

[0018] Furthermore, the melt index of the ethylene-propylene copolymer polypropylene is measured to be 5-10 g / 10 min at 230° C. and 2.16 kg.

[0019] Furthermore, the melt index of the homopolypropylene is measured to be 1-5 g / 10 min at 230° C. and 2.16 kg.

[0020] Furthermore, the release functional layer further comprises 0.5-1 wt % of an anti-adhesive agent.

[0021] Furthermore, the core layer further comprises 0.5-1 wt% of an antistatic agent.

[0022] The present invention also provides a method for preparing any of the above-mentioned biaxially oriented polypropylene base films, comprising the following steps: coextruding the surface layer, core layer, and release functional layer and cooling them to form a resin sheet; stretching the resin sheet longitudinally and transversely; corona treating the surface layer and winding it, wherein the extrusion temperature of the surface layer and the core layer are both 220°C to 260°C, and the extrusion temperature of the release functional layer is 200°C to 250°C. This application adopts a coextrusion one-step molding process, which simplifies the processing process and reduces costs; corona treating the surface layer is beneficial to enhancing the surface tension of the surface layer, so that the surface layer of the biaxially oriented polypropylene base film has good adhesion, and an adhesive layer coating process can be achieved on the surface layer without a primer, and is used in the preparation of tape film. The biaxially oriented polypropylene base film prepared by the biaxially oriented process of the present invention has good bonding strength between the surface layer, the core layer, and the release functional layer, thereby enabling smooth coextrusion. The release functional layer has good release effect, and winding and unwinding are smooth, reducing costs and improving production efficiency.

[0023] The present invention also provides an adhesive tape comprising any of the aforementioned biaxially oriented polypropylene base films, further comprising an adhesive layer, wherein the release functional layer, the core layer, the surface layer, and the adhesive layer are sequentially disposed. The adhesive tape of the present invention exhibits a low peeling force between the biaxially oriented polypropylene base film and the adhesive layer after winding, exhibiting good release properties and enabling smooth winding and unwinding.

[0024] Furthermore, the adhesive layer includes at least one of acrylic resin, water-based acrylic adhesive, and vinyl acetate resin.

[0025] In order to better understand and implement the present invention, the present invention is described in detail below. DETAILED DESCRIPTION

[0026] It should be clear that the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the embodiments of the present application.

[0027] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the embodiments of the present application. The singular forms "a," "the," and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0028] The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of devices and methods consistent with certain aspects of the present application, as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first," "second," "third," etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or precedence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0029] In addition, in this application, unless otherwise specified, "plurality" refers to two or more. "And / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0030] It should be understood that the embodiments of the present application are not limited to the precise structure described above, and various modifications and changes can be made without departing from the scope thereof. The scope of the embodiments of the present application is limited only by the appended claims.

[0031] As an embodiment of the present invention, this embodiment provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer and a surface layer arranged in sequence; the release functional layer comprises homopolypropylene, 5-10 wt% ethylene-propylene copolymer polypropylene and 20-30 wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer, the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer is copolymerized by a fluorinated polysiloxane segment and an ethylene-norbornene segment, the fluorinated polysiloxane segment is copolymerized and connected by 3 to 4 fluorinated siloxane units, and the ethylene-norbornene segment is copolymerized and connected by 1 to 2 ethylene-norbornene units; the core layer comprises homopolypropylene; the surface layer comprises ethylene-propylene copolymer polypropylene and 10-20 wt% polymethyl methacrylate grafted ethylene vinyl acetate copolymer.

[0032] Furthermore, the melt index of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer measured at 190° C. and 2.16 kg is 50-100 g / 10 min.

[0033] Furthermore, the surface layer further comprises 0.5-1 wt% of cross-linked polymethyl methacrylate particles.

[0034] Furthermore, the content of polymethyl methacrylate in the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 20-40 wt %; and the number average molecular weight of the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 20,000-22,000 g / mol.

[0035] Furthermore, the melting point of the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 90-100°C.

[0036] Furthermore, the melting point of the ethylene vinyl acetate copolymer in the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 80-90° C., and the content of vinyl acetate in the ethylene vinyl acetate copolymer is 15-25 wt %.

[0037] Furthermore, the thickness of the release functional layer is 1-2 μm, the thickness of the surface layer is 1-2 μm, and the thickness of the biaxially oriented polypropylene base film is 12-25 μm.

[0038] The present invention also provides a method for preparing any of the above-mentioned biaxially oriented polypropylene base films, comprising the following steps: co-extruding the surface layer, core layer and release functional layer and cooling them to form a resin sheet; longitudinally stretching and transversely stretching the resin sheet; corona treating the surface layer and winding it up, wherein the extrusion temperatures of the surface layer and the core layer are both 220°C to 260°C, and the extrusion temperature of the release functional layer is 200°C to 250°C.

[0039] The present invention also provides a tape film of any of the above-mentioned biaxially oriented polypropylene-based films, further comprising an adhesive layer, wherein the release functional layer, the core layer, the surface layer and the adhesive layer are arranged in sequence.

[0040] Furthermore, the adhesive layer includes at least one of acrylic resin, water-based acrylic adhesive, and vinyl acetate resin.

[0041] The physical properties and testing methods of the embodiments and comparative examples of the present invention are as follows:

[0042] Melt index (melt mass flow rate MFR) is determined according to GB / T3682-2018;

[0043] The 180° peeling force test of the release film was carried out by referring to the national standard GB / T 25256-2010 to measure the peeling force of the base film. The test was carried out in a high humidity environment. The details are as follows: (1) Evaluation of the peeling force of the release functional layer: a 3M standard pressure-sensitive adhesive tape with a width of 25 mm was used to stick it on the BOPP base film of the patent with a width of 25 mm (bonded to the release functional layer). The pressure roller was rolled back and forth twice at a speed of about 10 mm / s. The test was carried out at a temperature of 23°C ± 2°C, a relative humidity of 80% ± 5%, and a pressure of 70 g / cm2 The test was carried out under the pressure of 20 hours, and then tested with a tensile machine at 180 degrees. The relative humidity of the test environment was 80% ± 5%. (2) Evaluation of the peeling force of the surface layer: a 3M standard pressure-sensitive adhesive tape with a width of 25 mm was used to stick it on the release film of the present invention (adhered to the surface layer) with a width of 25 mm. The pressure roller was rolled back and forth twice at a speed of about 10 mm / s. The test was carried out under the temperature of 23℃ ± 2℃, the relative humidity of 80% ± 5% and the pressure of 70g / cm 2 The samples were placed under pressure for 20 hours, and then tested at 180° using a tensile testing machine. The relative humidity of the test environment was 80% ± 5%.

[0044] The melt index of homopolymer polypropylene is: 3.0 g / 10 min (test conditions: 190°C, 2.16 kg);

[0045] The melt index of ethylene-propylene copolymer polypropylene is: 7.5g / 10min (test conditions: 230℃, 2.16kg);

[0046] The melt index of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer is 60 g / 10 min (test conditions: 190° C., 2.16 kg).

[0047] The fluorinated siloxane unit is methyl(trifluoropropyl)siloxane;

[0048] The melting point of the ethylene vinyl acetate copolymer in the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 85° C., and the content of vinyl acetate in the ethylene vinyl acetate copolymer is 20 wt %;

[0049] The anti-adhesive agent in the release functional layer is silicon dioxide;

[0050] The antistatic agent in the core layer is glyceryl stearate;

[0051] The adhesive layer adopts water-based acrylic adhesive.

[0052] It should be noted that the proportions described in the embodiments or comparative examples of the present invention are all percentages by weight.

[0053] Example 1

[0054] This embodiment provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing each layer of resin of the biaxially oriented polypropylene base film of this embodiment comprises the following steps:

[0055] Preparation of release functional layer resin: Take 71wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 20wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 1 ethylene-norbornene copolymer unit, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0056] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0057] Preparation of surface resin: 89 wt% ethylene-propylene copolymerized polypropylene, 10 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 20 wt%, number average molecular weight Mn is 20,000 g / mol, melting point Tm is 90°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0058] The preparation method of the BOPP film of this embodiment includes the following steps: introducing the surface layer resin, the core layer resin and the release functional layer resin into an extruder for co-extrusion, and merging them at a T-shaped die after passing through a flow channel distributor to form a resin melt, wherein the extrusion temperature of the surface layer and the core layer is 250°C, and the extrusion temperature of the release functional layer is 230°C; the resin melt is then cooled by a chilled roller at 28°C and cast to obtain a resin sheet; the resin sheet is preheated at 130°C and longitudinally stretched 5 times, then introduced into a transverse stretching device, preheated at 162°C and transversely stretched 8.5 times, and finally wound after corona treatment (corona power 25w.min / m); then aging treatment is performed, and the sheet is cut according to the required specifications and packaged to obtain the described biaxially oriented polypropylene base film.

[0059] The biaxially oriented polypropylene base film is 20 μm thick, with a 2 μm release layer, a 17 μm core layer, and a 1 μm surface layer. During the production process, the film can be wound and unwound smoothly.

[0060] A layer of adhesive was applied to the surface of the biaxially oriented polypropylene base film of this embodiment to form a 5 μm thick adhesive layer to obtain an adhesive tape film. During the preparation process, the tape was rolled up and unrolled smoothly.

[0061] Example 2

[0062] This embodiment provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing each layer of resin of the biaxially oriented polypropylene base film of this embodiment comprises the following steps:

[0063] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0064] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0065] Preparation of surface resin: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 30 wt%, number average molecular weight Mn is 21000 g / mol, melting point Tm is 95°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0066] The preparation method of the biaxially oriented polypropylene base film of this embodiment is the same as that of Example 1, so it is not described in detail.

[0067] The biaxially oriented polypropylene base film is 20 μm thick, with a 2 μm release layer, a 17 μm core layer, and a 1 μm surface layer. During the production process, the film can be wound and unwound smoothly.

[0068] A layer of adhesive was applied to the surface of the biaxially oriented polypropylene base film of this embodiment to form a 5 μm thick adhesive layer to obtain an adhesive tape film. During the preparation process, the tape was rolled up and unrolled smoothly.

[0069] Example 3

[0070] This embodiment provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing each layer of resin of the biaxially oriented polypropylene base film of this embodiment comprises the following steps:

[0071] Preparation of release functional layer resin: Take 61wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 30wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 4 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0072] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0073] Preparation of surface resin: 79 wt% ethylene-propylene copolymerized polypropylene, 20 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 40 wt%, number average molecular weight Mn is 20,000 g / mol, melting point Tm is 100°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0074] The preparation method of the biaxially oriented polypropylene base film of this embodiment is the same as that of Example 1, so it is not described in detail.

[0075] The biaxially oriented polypropylene base film is 20 μm thick, with a 2 μm release layer, a 17 μm core layer, and a 1 μm surface layer. During the production process, the film can be wound and unwound smoothly.

[0076] A layer of adhesive was applied to the surface of the biaxially oriented polypropylene base film of this embodiment to form a 5 μm thick adhesive layer to obtain an adhesive tape film. During the preparation process, the tape was rolled up and unrolled smoothly.

[0077] Comparative Example 1

[0078] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0079] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0080] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0081] Preparation of surface resin: Take 91wt% ethylene-propylene copolymer polypropylene, 8wt% polymethyl methacrylate grafted ethylene vinyl acetate copolymer (PMMA content is 30wt%, number average molecular weight Mn is 21000g / mol, melting point Tm is 95℃) and 1wt% cross-linked PMMA particles and mix them evenly to obtain the surface resin.

[0082] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0083] The biaxially oriented polypropylene base film is 20 μm thick, with a 2 μm release layer, a 17 μm core layer, and a 1 μm surface layer. During the production process, the film can be wound and unwound smoothly.

[0084] A layer of adhesive was coated on the surface of the biaxially oriented polypropylene base film of this comparative example to form an adhesive layer with a thickness of 5 μm to obtain an adhesive tape film. During the preparation process, the film was wound and unwound smoothly.

[0085] Comparative Example 2

[0086] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0087] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0088] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0089] Preparation of surface resin: Take 76wt% ethylene-propylene copolymer polypropylene, 23wt% polymethyl methacrylate grafted ethylene vinyl acetate copolymer (PMMA content is 30wt%, number average molecular weight Mn is 21000g / mol, melting point Tm is 95℃) and 1wt% cross-linked PMMA particles and mix them evenly to obtain the surface resin.

[0090] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0091] The biaxially oriented polypropylene base film is 20 μm thick, with a 2 μm release layer, a 17 μm core layer, and a 1 μm surface layer. During the production process, the winding and unwinding process was not smooth, and the rolls sometimes stuck.

[0092] A layer of adhesive was coated on the surface of the biaxially oriented polypropylene base film of this comparative example to form an adhesive layer with a thickness of 5 μm to obtain an adhesive tape film. During the preparation process, the film was wound and unwound smoothly.

[0093] Comparative Example 3

[0094] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0095] Preparation of release functional layer resin: Take 73wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 18wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0096] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0097] Preparation of surface resin: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 30 wt%, number average molecular weight Mn is 21000 g / mol, melting point Tm is 95°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0098] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0099] The biaxially oriented polypropylene base film is 20 μm thick, with a 2 μm release layer, a 17 μm core layer, and a 1 μm surface layer. During the production process, the film can be wound and unwound smoothly.

[0100] A layer of adhesive was applied to the surface of the biaxially oriented polypropylene base film of this comparative example to form a 5 μm thick adhesive layer to obtain an adhesive tape film.

[0101] Comparative Example 4

[0102] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0103] Preparation of release functional layer resin: Take 59wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 32wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0104] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0105] Preparation of surface resin: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 30 wt%, number average molecular weight Mn is 21000 g / mol, melting point Tm is 95°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0106] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0107] The biaxially oriented polypropylene base film has a thickness of 20 μm, of which the release functional layer is 2 μm thick, the core layer is 17 μm thick, and the surface layer is 1 μm thick. During the preparation process, the production smoothness is poor and stretching film formation is difficult.

[0108] A layer of adhesive was coated on the surface of the biaxially oriented polypropylene base film of this comparative example to form an adhesive layer with a thickness of 5 μm to obtain an adhesive tape film. During the preparation process, the film was wound and unwound smoothly.

[0109] Comparative Example 5

[0110] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0111] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0112] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0113] Preparation of surface resin: Take 84wt% of ethylene-propylene copolymer polypropylene, 15wt% of ethylene-vinyl acetate copolymer (the content of vinyl acetate (VA) is 20wt%, the melt index of ethylene-vinyl acetate copolymer measured at 230℃ and 2.16kg is 15g / 10min, and the melting point Tm is 85℃) and 1wt% of cross-linked PMMA particles and mix them evenly to obtain the surface resin.

[0114] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0115] The biaxially oriented polypropylene base film has a thickness of 20 μm, of which the release functional layer has a thickness of 2 μm, the core layer has a thickness of 17 μm, and the surface layer has a thickness of 1 μm. During the production process, the production was smooth.

[0116] A layer of adhesive was applied to the surface of the biaxially oriented polypropylene base film of this comparative example to form a 5 μm thick adhesive layer to obtain an adhesive tape film. During the preparation process, the winding and unwinding process was not smooth and debonding occurred.

[0117] Comparative Example 6

[0118] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0119] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0120] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0121] Preparation of surface resin: Take 84wt% ethylene-propylene copolymer polypropylene, 15wt% polymethyl methacrylate grafted ethylene vinyl acetate copolymer (PMMA content is 50wt%, number average molecular weight Mn is 21000g / mol, melting point Tm is 95℃) and 1wt% cross-linked PMMA particles and mix them evenly to obtain the surface resin.

[0122] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0123] The biaxially oriented polypropylene base film has a thickness of 20 μm, of which the release functional layer has a thickness of 2 μm, the core layer has a thickness of 17 μm, and the surface layer has a thickness of 1 μm. During the production process, the production smoothness was poor and there was some sticking to the roller.

[0124] A layer of adhesive was applied to the surface of the biaxially oriented polypropylene base film of this comparative example to form a 5 μm thick adhesive layer to obtain an adhesive tape film.

[0125] Comparative Example 7

[0126] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0127] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane and ethylene-norbornene copolymer blend (the blending molar ratio of fluorinated polysiloxane and ethylene-norbornene copolymer is 3:2, and the melt index of the blend is 60g / 10min (test conditions: 190°C, 2.16kg)) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0128] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0129] Preparation of surface resin: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 30 wt%, number average molecular weight Mn is 21000 g / mol, melting point Tm is 95°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0130] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0131] The biaxially oriented polypropylene base film has a thickness of 20 μm, of which the release functional layer has a thickness of 2 μm, the core layer has a thickness of 17 μm, and the surface layer has a thickness of 1 μm. During the production process, the production was smooth.

[0132] A layer of adhesive was applied to the surface of the biaxially oriented polypropylene base film of this comparative example to form a 5 μm thick adhesive layer to obtain an adhesive tape film.

[0133] Comparative Example 8

[0134] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0135] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene norbornene copolymer segment is composed of 3 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 3 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0136] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0137] Preparation of surface resin: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 30 wt%, number average molecular weight Mn is 21000 g / mol, melting point Tm is 95°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0138] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0139] The thickness of the biaxially oriented polypropylene base film is 20 μm, of which the release functional layer is 2 μm thick, the core layer is 17 μm thick, and the surface layer is 1 μm thick. During the preparation process, the production smoothness is poor and biaxially oriented film formation is difficult.

[0140] A layer of adhesive was coated on the surface of the biaxially oriented polypropylene base film of this comparative example to form an adhesive layer with a thickness of 5 μm to obtain an adhesive tape film. During the preparation process, the film was wound and unwound smoothly.

[0141] Comparative Example 9

[0142] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0143] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 1 fluorinated silicone copolymer unit connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0144] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0145] Preparation of surface resin: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 30 wt%, number average molecular weight Mn is 21000 g / mol, melting point Tm is 95°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0146] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0147] The biaxially oriented polypropylene base film is 20 μm thick, with a 2 μm release layer, a 17 μm core layer, and a 1 μm surface layer. During the production process, the winding and unwinding process was not smooth enough.

[0148] A layer of adhesive was applied to the surface of the biaxially oriented polypropylene base film of this comparative example to form a 5 μm thick adhesive layer to obtain an adhesive tape film.

[0149] Comparative Example 10

[0150] This comparative example provides a biaxially oriented polypropylene base film, comprising a release functional layer, a core layer, and a surface layer arranged in sequence. The method for preparing the resin layers of the biaxially oriented polypropylene base film of this comparative example comprises the following steps:

[0151] Preparation of release functional layer resin: Take 66wt% homopolypropylene, 8wt% ethylene-propylene copolymer polypropylene, 25wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment is composed of 2 ethylene-norbornene copolymer units connected, and fluorinated polysiloxane copolymer segment is composed of 5 fluorinated silicone copolymer units connected) and 1wt% anti-blocking agent and mix them evenly to obtain a release functional layer resin.

[0152] Preparation of core layer resin: 99 wt% homopolypropylene and 1 wt% antistatic agent were mixed evenly to obtain core layer resin.

[0153] Preparation of surface resin: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 30 wt%, number average molecular weight Mn is 21000 g / mol, melting point Tm is 95°C) and 1 wt% cross-linked PMMA particles are mixed evenly to obtain the surface resin.

[0154] The preparation method of the biaxially oriented polypropylene base film of this comparative example is the same as that of Example 1, so it is not described in detail.

[0155] The biaxially oriented polypropylene base film is 20 μm thick, with a 2 μm release layer, a 17 μm core layer, and a 1 μm surface layer. During the production process, the film can be wound and unwound smoothly.

[0156] A layer of adhesive was coated on the surface of the biaxially oriented polypropylene base film of this comparative example to form an adhesive layer with a thickness of 5 μm to obtain an adhesive tape film. During the preparation process, the film was wound and unwound smoothly.

[0157] The performance test results of the biaxially oriented polypropylene base films of Examples 1 to 3 and Comparative Examples 1 to 10 are shown in Table 1 below.

[0158] Table 1

[0159]

[0160] From the above performance test data, we can see that:

[0161] The biaxially oriented polypropylene films of Examples 1-3, on the one hand, have a low release layer, preventing the surface layer and adhesive layer from adhering to the release layer during unwinding without the need for silicone oil coating. This ensures smooth unwinding and rewinding of the tape film and biaxially oriented polypropylene film, and enhances the barrier properties of the release layer. This helps maintain adhesion between the adhesive layer and the substrate in high-humidity environments, allowing for prolonged use in such environments. On the other hand, the surface layer has a high release force, ensuring good adhesion between the surface layer and the adhesive layer without the need for a primer coating. This helps ensure that the adhesive layer does not separate from the surface layer during unwinding, allowing for smooth removal and reuse after use. Furthermore, the addition of a fluorinated polysiloxane-functionalized ethylene-norbornene block copolymer also enhances the barrier properties of the release layer. This synergistic effect of the enhanced peel force of the surface layer helps maintain the high adhesion of the tape film in high-humidity environments, allowing for prolonged use in such environments.

[0162] According to the data of Comparative Example 1 and Example 2, under the same conditions of the release functional layer, the content of polymethyl methacrylate grafted ethylene vinyl acetate copolymer in the surface layer of Comparative Example 1 is too low, and the peeling force of the surface layer of Comparative Example 1 is significantly lower than the peeling force of the surface layer of Example 2, which is not conducive to effectively ensuring the bonding strength between the surface layer and the adhesive layer of the tape film, there is a risk of degumming, and it is not conducive to application in high-humidity environments.

[0163] According to the data of Comparative Example 2 and Example 2, under the same conditions of the release functional layer, the content of polymethyl methacrylate grafted ethylene vinyl acetate copolymer in the surface layer of Comparative Example 2 is too high, resulting in the surface layer being too sticky. The peeling force of the surface layer of Comparative Example 2 is significantly higher than the peeling force of the surface layer of Example 2, but the film-forming property is poor during the production process, resulting in the phenomenon of sticking to the roller, and the smoothness of winding and unwinding of the base film itself is poor.

[0164] Based on the data from Comparative Example 3 and Example 2, under identical surface layer conditions, the low content of the fluorosilicone-functionalized ethylene norbornene block copolymer in the release layer of Comparative Example 3 resulted in insignificant release improvement. The peel force of the release layer of Comparative Example 3 was significantly higher than that of the release layer of Example 2, hindering the desorption of the adhesive layer from the release layer. The resulting tape film also suffered from issues with smooth winding and unwinding, which also hindered the smooth winding and unwinding of the BOPP base film itself. Furthermore, the low content of the fluorosilicone-functionalized ethylene norbornene block copolymer reduced the barrier properties of the release layer, resulting in slightly lower peel force on the surface layer of Comparative Example 3 than in Example 2.

[0165] According to the data of Comparative Example 4 and Example 2, under the same conditions of the surface layer, the content of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer in the release functional layer of Comparative Example 4 is too high, and the peel force of the release functional layer of Comparative Example 4 is significantly lower than the peel force of the release functional layer of Example 2, but the biaxially oriented polypropylene base film of Comparative Example 4 has poor film-forming properties during production.

[0166] According to the data of Comparative Example 5 and Example 2, Comparative Example 5 directly uses unmodified ethylene vinyl acetate copolymer without grafting polymethyl methacrylate, and the viscosity-increasing effect is not as good as that of polymethyl methacrylate grafted ethylene vinyl acetate copolymer. The surface peeling force of Comparative Example 5 is significantly lower than the surface peeling force of Example 2, which is not conducive to effectively ensuring the bonding force between the surface layer and the adhesive layer of the tape film, there is a risk of degumming, and it is not conducive to application in high humidity environments.

[0167] According to the data of Comparative Example 6 and Example 2, the PMMA content in the polymethyl methacrylate grafted ethylene vinyl acetate copolymer of Comparative Example 6 is relatively high. Although the surface peeling force of Comparative Example 6 is significantly higher than that of Example 2, the surface layer of the biaxially oriented polypropylene base film of Comparative Example 6 is too sticky, and the film-forming property is poor during the production process, and smooth production cannot be achieved.

[0168] According to the data of Comparative Example 7 and Example 2, the release functional layer of Comparative Example 7 contains a blend of fluorinated polysiloxane and ethylene-norbornene copolymer, and its compatibility and dispersion uniformity in the release functional layer are worse than those of the fluorinated polysiloxane-functionalized ethylene-norbornene block copolymer. The peeling force of the release functional layer of Comparative Example 7 is slightly lower than that of the release functional layer of Example 2, and the surface of the BOPP base film of Comparative Example 7 has bright spots.

[0169] According to the data of Comparative Example 8 and Example 2, the number of ethylene-norbornene copolymer units constituting the ethylene-norbornene chain segments in the release functional layer of Comparative Example 8 is too large, and the peeling force of the release functional layer of Comparative Example 8 is lower than that of Example 2. Moreover, due to the improvement of the barrier property, the peeling force of the surface layer is greater than that of Example 2. However, Comparative Example 8 has the problem of being difficult to stretch into a film, which is not conducive to the smoothness of biaxial stretching.

[0170] According to the data of Comparative Example 9 and Example 2, under the same conditions of the surface layer, the fluorinated polysiloxane constituting the fluorinated polysiloxane chain segment in Comparative Example 9 is too little, and the improvement in release effect is not obvious. The peel force of the release functional layer of Comparative Example 9 is significantly higher than that of the release functional layer of Example 2, which is not conducive to the desorption of the adhesive layer and the release functional layer. The prepared tape film has the problem of not being smooth in winding and unwinding, which is also not conducive to the smoothness of winding and unwinding of the BOPP base film itself.

[0171] According to the data from Comparative Example 10 and Example 2, the release layer of Comparative Example 10 contains too much fluorinated polysiloxane that constitutes the fluorinated polysiloxane chain segment, and its compatibility and dispersion uniformity in the release layer are worse than those of the fluorinated polysiloxane-functionalized ethylene norbornene block copolymer. Although the release layer of Comparative Example 10 has a lower peel force than that of the release layer of Example 2, the BOPP base film of Comparative Example 10 has bright spots on its surface, which is not conducive to uniform release.

[0172] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to encompass such modifications and variations.

Claims

1. A biaxially oriented polypropylene base film, characterized in that: The invention comprises a release functional layer, a core layer and a surface layer arranged in sequence; the release functional layer comprises homopolypropylene, 5-10 wt% ethylene-propylene copolymerized polypropylene and 20-30 wt% fluorinated polysiloxane functionalized ethylene-norbornene block copolymer, the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer is copolymerized by a fluorinated polysiloxane segment and an ethylene-norbornene segment, the fluorinated polysiloxane segment is copolymerized and connected by 3-4 fluorinated siloxane units, and the ethylene-norbornene segment is copolymerized and connected by 1-2 ethylene-norbornene units; the core layer comprises homopolypropylene; the surface layer comprises ethylene-propylene copolymerized polypropylene and 10-20 wt% polymethyl methacrylate grafted ethylene vinyl acetate copolymer.

2. The biaxially oriented polypropylene base film according to claim 1, characterized in that The surface layer further comprises 0.5-1 wt% of cross-linked polymethyl methacrylate particles.

3. The biaxially oriented polypropylene base film according to claim 1, characterized in that The melt index of the fluorinated polysiloxane functionalized ethylene-norbornene block copolymer measured at 190° C. and 2.16 kg is 50-100 g / 10 min.

4. The biaxially oriented polypropylene base film according to claim 1, characterized in that The content of polymethyl methacrylate in the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 20-40 wt %; and the number average molecular weight of the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 20,000-22,000 g / mol.

5. The biaxially oriented polypropylene base film according to claim 1, characterized in that: The melting point of the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 90-100°C.

6. The biaxially oriented polypropylene base film according to claim 1, characterized in that: The melting point of the ethylene vinyl acetate copolymer in the polymethyl methacrylate grafted ethylene vinyl acetate copolymer is 80-90° C., and the content of vinyl acetate in the ethylene vinyl acetate copolymer is 15-25 wt %.

7. The biaxially oriented polypropylene base film according to claim 1, characterized in that: The thickness of the release functional layer is 1-2 μm, the thickness of the surface layer is 1-2 μm, and the thickness of the biaxially oriented polypropylene base film is 12-25 μm.

8. A method for preparing a biaxially oriented polypropylene base film according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: co-extruding the surface layer, the core layer and the release functional layer and cooling the co-extrusion to form a resin sheet; longitudinally stretching and transversely stretching the resin sheet; The surface layer is subjected to corona treatment and rolled up. The extrusion temperatures of the surface layer and the core layer are both 220° C. to 260° C., and the extrusion temperature of the release functional layer is 200° C. to 250° C.

9. An adhesive tape film comprising the biaxially oriented polypropylene base film according to any one of claims 1 to 7, characterized in that: It also includes an adhesive layer, and the release functional layer, the core layer, the surface layer and the adhesive layer are arranged in sequence.

10. The adhesive tape film according to claim 9, characterized in that The adhesive layer includes at least one of acrylic resin, water-based acrylic adhesive, and vinyl acetate resin.

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