A biaxially stretched polypropylene-based film, a method for manufacturing the same, and a tape film

Abstract

The present application relates to the field of film, particularly to a biaxially oriented polypropylene-based film and its preparation method and adhesive tape film, the base film sequentially comprises a release function layer, a core layer and a surface layer; the release function layer comprises homopolymer polypropylene, 5-10wt% ethylene-propylene copolymer polypropylene and 20-30wt% fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer, the fluorine-containing polysiloxane segment is connected by 3-4 fluorine-containing siloxane units, and the ethylene-norbornene segment is connected by 1-2 ethylene-norbornene units; the core layer comprises homopolymer polypropylene; the surface layer comprises ethylene-propylene copolymer polypropylene and 10-20wt% PMMA-g-EVA. The present application can reduce the release force of the release function layer and improve the barrier property under the premise of ensuring the uniformity of the release, so that the prepared base film and 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 primer, and the adhesive tape film is beneficial to use in a high-humidity environment for a long time.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of film, in particular to a biaxially stretched polypropylene-based film, a preparation method thereof and a tape film. BACKGROUND

[0002] The existing tape film generally comprises, from bottom to top, a substrate layer, a primer layer and an adhesive layer, wherein the substrate layer is usually a biaxially stretched polypropylene film (BOPP film for short) or a biaxially stretched polyester film (BOPET film for short), and the thickness is 12-20 μm; the BOPP film has the characteristics of high transparency, good brightness, waterproofness, heat resistance and low price, and is an ideal material for the tape film.

[0003] In actual application, the tape film is usually stored after being wound, and the adhesive layer covers the other side of the substrate layer after being wound. However, since the surface energy of the BOPP film is low and the polarity of the acrylate in the glue used for preparing the adhesive layer is very strong, the adhesive layer is easy to be bonded with the other side of the substrate layer, and then the phenomena of being unable to unwind, the adhesive layer being separated from the primer layer or the adhesive layer being separated from the substrate layer with the primer layer are caused. Therefore, when the BOPP film is used as the substrate layer, a material with lower surface energy such as silicone oil needs to be coated on the other side of the substrate layer to make the other side of the substrate layer easy to be peeled from the adhesive layer in use.

[0004] However, the inventors have found through a large number of practices that the existing tape film still has the following defects after being coated with silicone oil: first, the coating process needs to be used to coat the material with lower surface energy on the other side of the substrate layer, which increases the production process and processing cost, and it is difficult to ensure the uniformity of the coating, and the silicone oil is easy to migrate after being coated, which affects the adhesion strength between the adhesive layer and the primer layer; second, the existing tape film usually has the problem of insufficient adhesion when being exposed in a high-humidity environment for a long time; third, the adhesion between the adhesive layer and the substrate layer of the existing tape film is insufficient, which causes the adhesive layer to be separated from the substrate layer when the tape film is unwound or when the tape film that has been pasted is torn off to be used again, and the separated part of the adhesive layer needs to be cut off or a new tape film needs to be used for pasting. SUMMARY

[0005] Based on this, the purpose of the present application is to provide a biaxially oriented polypropylene-based film and a preparation method thereof. The biaxially oriented polypropylene-based film of the present application, on the one hand, by adding a certain amount of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer in the release functional layer, reduces the release force of the release functional layer under the premise of ensuring the compatibility of the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer and the homopolymer polypropylene, and realizes the smoothness of the adhesive tape film and the biaxially oriented polypropylene-based film without coating silicone oil; on the other hand, by adding poly methyl methacrylate grafted ethylene vinyl acetate copolymer (PMMA-g-EVA) on the surface layer, the adhesion between the surface layer and the adhesive layer is ensured without coating primer on the surface layer, the release force of the surface layer is enhanced, which is beneficial to ensure that the adhesive tape film prepared does not separate from the surface layer during unwinding, and can be easily torn off for repeated use after use. In addition, the addition of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer also improves the barrier property of the release functional layer, which is beneficial to the adhesive tape film to maintain high adhesion under high humidity environment, and can be used in high humidity environment for a long time.

[0006] The technical scheme of the present application is realized by the following way:

[0007] A biaxially oriented polypropylene-based film, comprising a release functional layer, a core layer and a surface layer arranged in sequence; the release functional layer comprises homopolymer polypropylene, 5-10wt% ethylene-propylene copolymerized polypropylene and 20-30wt% fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer, the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer is copolymerized by fluorine-containing polysiloxane segments and ethylene-norbornene segments, the fluorine-containing polysiloxane segments are copolymerized by 3-4 fluorine-containing siloxane units, and the ethylene-norbornene segments are copolymerized by 1-2 ethylene-norbornene units; the core layer comprises homopolymer polypropylene; and the surface layer comprises ethylene-propylene copolymerized polypropylene and 10-20wt% poly methyl methacrylate grafted ethylene vinyl acetate copolymer.

[0008] The bidirectional stretching polypropylene-based film provided by the application, the bidirectional stretching polypropylene-based film provided by the application, on one hand, a certain amount of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer and ethylene-propylene copolymer polypropylene are added in the release function layer, the release force of the release function layer is reduced under the premise of ensuring the compatibility of the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer and the homopolymer polypropylene, and the unwinding and winding smoothness of the adhesive tape film and the bidirectional stretching polypropylene-based film can be realized without coating silicone oil; on the other hand, by adding poly-methyl-methacrylate grafted ethylene-vinyl acetate copolymer (PMMA-g-EVA) on the surface layer, the adhesion between the surface layer and the adhesive layer can be ensured without coating a primer on the surface layer, the release force of the surface layer is enhanced, and the surface layer is beneficial to ensuring that the adhesive layer is not separated from the surface layer when the prepared adhesive tape film is unwound and can be torn off smoothly after use to be reused. In addition, the addition of the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer also improves the barrier property of the release function layer, and under the synergistic effect of the enhanced release force of the surface layer, the adhesive tape film can still maintain high adhesion in a high-humidity environment, and can be used in a high-humidity environment for a long time.

[0009] The application adds 20-30wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer in the release function layer and limits the composition of the molecular chain, improves the release effect of the release function layer while improving the barrier property of the release function layer, realizes the unwinding and winding smoothness of the adhesive tape film and the bidirectional stretching polypropylene-based film without coating silicone oil, and under the synergistic effect of the enhanced release force of the surface layer, the adhesive tape film is beneficial to use in a high-humidity environment for a long time and maintain the adhesion between the adhesive layer and the substrate in a high-humidity environment; specifically, if the content of the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer is less than 20wt%, the release effect is not obviously improved, and it is also not beneficial to the unwinding and winding smoothness of the base film itself in the production process, and it will also have a certain adverse effect on the release force of the surface layer; if the content of the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer is more than 30wt%, it is not conducive to the effective co-extrusion of the release function layer and the core layer, and it is not conducive to the smoothness of bidirectional stretching, and cracks will be generated during production; if the number of ethylene-norbornene units in a single ethylene-norbornene segment is greater than 2, the rigidity of the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer will be too large, which is not conducive to bidirectional stretching; if the number of polysiloxane units in a single polysiloxane segment is greater than 4, the compatibility of the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer with other components of the release function layer will be poor, which is not conducive to the uniformity of the release effect, and the final release effect will be poor.

[0010] On this basis, in order to ensure the compatibility of the fluorosilicone functionalized ethylene-norbornene block copolymer and the polypropylene in the release functional layer, 5-10wt% of ethylene-propylene copolymerized polypropylene is added in the release functional layer to ensure that the fluorosilicone functionalized ethylene-norbornene block copolymer can be uniformly dispersed in the release functional layer.

[0011] On the other hand, 10-20wt% of polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is added in the surface layer. The polymethyl methacrylate grafted ethylene-vinyl acetate copolymer, due to the introduction of amorphous polymethyl methacrylate (PMMA) through graft polymerization process, disturbs the filling of the crystalline polyethylene segment, reduces the crystallinity, is conducive to the formation of smooth microstructure, has high adhesion area, and increases the content of polar ester group, which is more conducive to the improvement of the adhesion between the surface layer and the adhesive layer, so that the adhesive layer can be coated directly on the surface layer without coating a primer layer. In addition, the PMMA-g-EVA has a short PMMA graft chain, which is further conducive to the formation of 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 compatibilized and have high adhesion, which is conducive to the realization of coating the adhesive layer without coating a primer layer.

[0012] Further, the melt index of the fluorosilicone functionalized ethylene-norbornene block copolymer is 50-100g / 10min measured at 190℃ under a load of 2.16kg. The use of fluorosilicone functionalized ethylene-norbornene block copolymer within the limited melt index range is conducive to improving the fluidity required by the release functional layer and ensuring the adhesion of the longitudinal stretching roller to the thick sheet during production.

[0013] Further, the surface layer further comprises 0.5-1wt% of crosslinked polymethyl methacrylate particles. The crosslinked polymethyl methacrylate particles can be uniformly dispersed in the surface layer, and the addition of crosslinked polymethyl methacrylate particles in the surface layer is conducive to ensuring the smoothness of the biaxially stretched polypropylene-based film during unwinding and winding.

[0014] Further, the content of the polymethyl methacrylate in the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 20-40 wt%; the number average molecular weight of the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 20000-22000 g / mol. The application also limits the content of PMMA in PMMA-g-EVA. If the content of PMMA is greater than 40 wt%, it will cause the viscosity of PMMA-g-EVA to be too large, the compatibility of PMMA-g-EVA with ethylene-propylene copolymerized polypropylene to be poor, and it is not conducive to obtaining a thick sheet suitable for biaxial stretching, and there may be a problem of sticking to the roller. If the content of PMMA is less than 20 wt%, it is not 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 limited range of the number average molecular weight, the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer has good melt matching with the ethylene-propylene copolymerized polypropylene in the surface layer.

[0015] Further, the melting point of the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 90-100℃. EVA generally has a lower melting point and poor thermal stability, and the melting point of the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 90-100℃, which has better thermal stability than EVA.

[0016] Further, the melting point of the ethylene-vinyl acetate copolymer in the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 80-90℃, and the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 15-25 wt%, which is conducive to maintaining the thermal stability of the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer and preventing degradation at the processing temperature of the application.

[0017] Further, 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 stretched polypropylene-based film is 12-25 μm. If the thickness of the release functional layer is > 2 μm, it will cause the haze of the biaxially stretched polypropylene-based film to increase, and the production cost will increase. If the thickness of the release functional layer is < 1 μm, it is difficult to achieve good release effect, which is not conducive to the use of the adhesive film in the application.

[0018] Further, the melt index of the ethylene-propylene copolymerized polypropylene is 5-10 g / 10 min measured at 230℃ under a load of 2.16 kg.

[0019] Further, the melt index of the homopolymer polypropylene is 1-5 g / 10 min measured at 230℃ under a load of 2.16 kg.

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

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

[0022] The application further provides a preparation method of the biaxially stretched polypropylene-based film, comprising the following steps: co-extruding and cooling the surface layer, the core layer and the release functional layer to form a resin sheet; longitudinally and transversely stretching the resin sheet; performing corona treatment on the surface layer; and winding, wherein the extrusion temperature of the surface layer and the core layer is 220-260 DEG C, and the extrusion temperature of the release functional layer is 200-250 DEG C. The application adopts a co-extrusion one-step forming process, simplifies the processing technology, and reduces the cost; the surface layer is subjected to corona treatment, which is beneficial to enhancing the surface tension of the surface layer, so that the surface layer of the biaxially stretched polypropylene-based film has good adhesion, and the coating adhesive layer process can be realized on the surface layer without primer, and is applied to the preparation of adhesive tape film. The biaxially stretched polypropylene-based film prepared by the biaxial stretching process has good bonding force between the surface layer, the core layer and the release functional layer, so that the co-extrusion is smooth, the release functional layer has good release effect, the winding is smooth, the cost is reduced, and the production efficiency is improved.

[0023] The application further provides an adhesive tape film comprising the biaxially stretched polypropylene-based film, further comprising an adhesive layer, wherein the release functional layer, the core layer, the surface layer and the adhesive layer are sequentially arranged. The adhesive tape film has small required peeling force between the biaxially stretched polypropylene-based film and the adhesive layer after winding, has good release effect, and has smooth winding and unwinding.

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

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

[0026] It should be clear that the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

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

[0028] The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims. In this description of the present application, it should be understood that the terms "first", "second", "third", etc., merely identify similar objects in order to distinguish one from another, and are not necessarily used to describe a particular sequential or chronological order, nor are they used to indicate or imply relative importance. The specific meaning of the above terms in the present application can be understood according to the specific circumstances by those of ordinary skill in the art.

[0029] In addition, in the description of the present application, "a plurality of" means two or more, unless otherwise specified. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the front and rear associated objects are in an "or" relationship.

[0030] It should be understood that the embodiments of the present application are not limited to the exact structures 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 application, the embodiment provides a biaxially stretched polypropylene-based film, comprising a release function layer, a core layer and a surface layer arranged in sequence; the release function layer comprises homopolymer polypropylene, 5-10wt% ethylene-propylene copolymer polypropylene and 20-30wt% fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer, the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer is copolymerized by fluorine-containing polysiloxane segments and ethylene-norbornene segments, the fluorine-containing polysiloxane segments are copolymerized by 3-4 fluorine-containing siloxane units, and the ethylene-norbornene segments are copolymerized by 1-2 ethylene-norbornene units; the core layer comprises homopolymer polypropylene; and the surface layer comprises ethylene-propylene copolymer polypropylene and 10-20wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer.

[0032] Further, the melt index of the fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer is 50-100g / 10min measured at 190℃ under the condition of 2.16kg.

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

[0034] Further, the content of the polymethyl methacrylate in the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 20-40 wt%; the number average molecular weight of the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 20000-22000 g / mol.

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

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

[0037] Further, 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 stretched polypropylene-based film is 12-25 μm.

[0038] The application also provides a preparation method of the biaxially stretched polypropylene-based film, comprising the following steps: co-extruding and cooling the surface layer, the core layer and the release functional layer to form a resin sheet; longitudinally and transversely stretching the resin sheet; and performing corona treatment on the surface layer, and winding, wherein the extrusion temperature of the surface layer and the core layer is 220℃-260℃, and the extrusion temperature of the release functional layer is 200℃-250℃.

[0039] The application also provides a tape film of the biaxially stretched polypropylene-based film, further comprising an adhesive layer, and the release functional layer, the core layer, the surface layer and the adhesive layer are sequentially arranged.

[0040] Further, the adhesive layer comprises at least one of an acrylic resin, a water-based acrylic adhesive and a vinyl acetate resin.

[0041] The physical property indexes of the embodiments or the comparative examples of the application and the test methods thereof are as follows:

[0042] The melt index (melt mass flow rate MFR) is determined according to GB / T 3682-2018;

[0043] The release film 180° peel force test is performed according to the national standard GB / T 25256-2010 for the base film, and the test is performed in a high humidity environment, and the specific steps are as follows: (1) release functional layer peel force evaluation: a 3M standard pressure-sensitive adhesive tape with a width of 25 mm is adhered to the BOPP base film (adhered to the release functional layer) of the application with a width of 25 mm, and a pressure roller is used to roll back and forth twice at a speed of about 10 mm / s, and the test is performed at a temperature of 23℃±2℃, a relative humidity of 80%±5%, and a pressure of 70 g / cm2.2 (1) Pressed under pressure for 20 hours, and then tested at 180° with a tensile testing machine. The relative humidity of the test environment was 80% ± 5%. (2) Evaluation of the peel force of the surface layer: A 25mm wide 3M standard pressure-sensitive tape was attached to a 25mm wide release film of this patent (adhesive to the surface layer). The film was rolled back and forth twice with a pressure roller at a speed of about 10mm / s. The test was conducted at a temperature of 23℃ ± 2℃, a relative humidity of 80% ± 5%, and a pressure of 70g / cm. 2 The sample was pressed 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 flow index of homopolymer polypropylene is 3.0 g / 10 min (test conditions: 190℃, 2.16 kg);

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

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

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

[0048] The ethylene vinyl acetate copolymer in the polymethyl methacrylate-grafted ethylene vinyl acetate copolymer has a melting point of 85°C, and the ethylene vinyl acetate copolymer contains 20 wt% vinyl acetate.

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

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

[0051] The adhesive layer uses a water-based acrylic adhesive.

[0052] It should be noted that the percentages mentioned in the embodiments or comparative examples of this invention are all weight percentages.

[0053] Example 1

[0054] This embodiment provides a biaxially oriented polypropylene (BOPP) base film, comprising a release functional layer, a core layer, and a surface layer sequentially disposed therefrom. The preparation method of each resin layer of the BOPP base film in this embodiment includes the following steps:

[0055] Preparation of the release functional layer resin: 71 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 20 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (the ethylene-norbornene copolymer segment is connected by 1 ethylene-norbornene copolymer unit, and the fluorine-containing polysiloxane copolymer segment is connected by 3 fluorine-containing siloxane copolymer units), and 1 wt% of anti-blocking agent are uniformly mixed to obtain the release functional layer resin.

[0056] Preparation of the core layer resin: 99 wt% of homopolymer polypropylene and 1 wt% of antistatic agent are uniformly mixed to obtain the core layer resin.

[0057] Preparation of the surface layer resin: 89 wt% of ethylene-propylene copolymer polypropylene, 10 wt% of polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 20 wt%, number average molecular weight Mn is 20000 g / mol, and melting point Tm is 90°C), and 1 wt% of crosslinked PMMA microparticles are uniformly mixed to obtain the surface layer resin.

[0058] The preparation method of the BOPP film of the present embodiment comprises the following steps: introducing the surface layer resin, the core layer resin, and the release functional layer resin into an extruder for co-extrusion, converging 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 quenching roller at 28°C and cast into a resin sheet; the resin sheet is preheated at 130°C and then stretched longitudinally by 5 times, followed by introduction into a transverse stretching device, stretched transversely by 8.5 times after preheating at 162°C, and finally wound up after corona treatment (corona power 25 w.min / m); then, aging treatment is performed, and the film is cut according to the required specifications, packaged, and obtained as the biaxially stretched polypropylene-based film.

[0059] The biaxially stretched polypropylene-based film has a thickness of 20 μm, wherein the thickness of the release functional layer is 2 μm, the thickness of the core layer is 17 μm, and the thickness of the surface layer is 1 μm. During the preparation process, the winding and unwinding are smooth.

[0060] In the surface layer of the biaxially stretched polypropylene-based film of the present embodiment, an adhesive layer with a thickness of 5 μm is coated to obtain an adhesive film. During the preparation process, the winding and unwinding are smooth.

[0061] Example 2

[0062] The present embodiment provides a biaxially stretched polypropylene-based film, which comprises a release functional layer, a core layer, and a surface layer arranged in sequence. The preparation method of the resin of each layer of the biaxially stretched polypropylene-based film of the present embodiment comprises the following steps:

[0063] Preparation of the release functional layer resin: 61 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 30 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (the ethylene-norbornene copolymer segment is connected by 2 ethylene-norbornene copolymer units, and the fluorine-containing polysiloxane copolymer segment is connected by 4 fluorine-containing siloxane copolymer units), and 1 wt% of anti-blocking agent are uniformly mixed to obtain the release functional layer resin.

[0064] Preparation of the core layer resin: 99 wt% of homopolymer polypropylene and 1 wt% of antistatic agent are uniformly mixed to obtain the core layer resin.

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

[0066] The preparation method of the biaxially stretched polypropylene-based film of the present example is the same as that of Example 1, and thus is not described herein.

[0067] The biaxially stretched polypropylene-based film has a thickness of 20 μm, wherein 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 preparation process, the winding and unwinding are smooth.

[0068] A biaxially stretched polypropylene-based film is prepared by coating a layer of adhesive on the surface layer of the biaxially stretched polypropylene-based film of the present example to form an adhesive layer with a thickness of 5 μm. During the preparation process, the winding and unwinding are smooth.

[0069] Example 3

[0070] The present example provides a biaxially stretched polypropylene-based film, which comprises a release functional layer, a core layer, and a surface layer arranged in sequence. The preparation method of the resin of each layer of the biaxially stretched polypropylene-based film of the present example comprises the following steps:

[0071] Preparation of the release functional layer resin: 61 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 30 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (the ethylene-norbornene copolymer segment is connected by 2 ethylene-norbornene copolymer units, and the fluorine-containing polysiloxane copolymer segment is connected by 4 fluorine-containing siloxane copolymer units), and 1 wt% of anti-blocking agent are uniformly mixed to obtain the release functional layer resin.

[0072] Preparation of the core layer resin: 99 wt% of homopolymer polypropylene and 1 wt% of antistatic agent are uniformly mixed to obtain the core layer resin.

[0073] Surface layer resin preparation: 91wt% ethylene-propylene copolymerized polypropylene, 8wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content 30wt%, number average molecular weight Mn 21000g / mol, melting point Tm 95°C) and 1wt% crosslinked PMMA microparticles were uniformly mixed to obtain the surface layer resin.

[0074] The preparation method of the biaxially stretched polypropylene-based film of the present example is the same as that of Example 1, and thus is not described herein.

[0075] The biaxially stretched polypropylene-based film has a thickness of 20μm, wherein the thickness of the release functional layer is 2μm, the thickness of the core layer is 17μm, and the thickness of the surface layer is 1μm. During the preparation process, the winding and unwinding are smooth.

[0076] In the biaxially stretched polypropylene-based film of the present example, an adhesive layer with a thickness of 5μm is coated on the surface layer to obtain an adhesive film. During the preparation process, the winding and unwinding are smooth.

[0077] Comparative Example 1

[0078] The present comparative example provides a biaxially stretched polypropylene-based film, which comprises a release functional layer, a core layer and a surface layer arranged in sequence. The preparation method of the biaxially stretched polypropylene-based film of the present comparative example comprises the following steps:

[0079] Release functional layer resin preparation: 66wt% homopolymerized polypropylene, 8wt% ethylene-propylene copolymerized polypropylene, 25wt% fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment connected by 2 ethylene-norbornene copolymer units, fluorine-containing polysiloxane copolymer segment connected by 3 fluorine-containing siloxane copolymer units) and 1wt% anti-blocking agent were uniformly mixed to obtain the release functional layer resin.

[0080] Core layer resin preparation: 99wt% homopolymerized polypropylene and 1wt% antistatic agent were uniformly mixed to obtain the core layer resin.

[0081] Surface layer resin preparation: 91wt% ethylene-propylene copolymerized polypropylene, 8wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content 30wt%, number average molecular weight Mn 21000g / mol, melting point Tm 95°C) and 1wt% crosslinked PMMA microparticles were uniformly mixed to obtain the surface layer resin.

[0082] The preparation method of the biaxially stretched polypropylene-based film of the present comparative example is the same as that of Example 1, and thus is not described herein.

[0083] The biaxially stretched polypropylene-based film has a thickness of 20μm, wherein the thickness of the release functional layer is 2μm, the thickness of the core layer is 17μm, and the thickness of the surface layer is 1μm. During the preparation process, the winding and unwinding are smooth.

[0084] A double-stretched polypropylene-based film of the present comparative example was coated with an adhesive on the surface layer to form an adhesive layer with a thickness of 5 μm, thereby obtaining an adhesive tape film. During the preparation process, the winding and unwinding was smooth.

[0085] Comparative Example 2

[0086] The present comparative example provides a double-stretched polypropylene-based film including a release functional layer, a core layer, and a surface layer arranged in sequence. The preparation method of the double-stretched polypropylene-based film of the present comparative example includes the following steps:

[0087] Preparation of the release functional layer resin: 66 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 25 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment connected by 2 ethylene-norbornene copolymer units, and fluorine-containing polysiloxane copolymer segment connected by 3 fluorine-containing siloxane copolymer units), and 1 wt% of anti-blocking agent were uniformly mixed to obtain the release functional layer resin.

[0088] Preparation of the core layer resin: 99 wt% of homopolymer polypropylene and 1 wt% of antistatic agent were uniformly mixed to obtain the core layer resin.

[0089] Preparation of the surface layer resin: 76 wt% of ethylene-propylene copolymer polypropylene, 23 wt% of polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content of 30 wt%, number average molecular weight Mn of 21000 g / mol, and melting point Tm of 95 °C), and 1 wt% of crosslinked PMMA microparticles were uniformly mixed to obtain the surface layer resin.

[0090] The preparation method of the double-stretched polypropylene-based film of the present comparative example is the same as that of Example 1, and thus a detailed description thereof will not be provided.

[0091] The double-stretched polypropylene-based film had a thickness of 20 μm, in which the release functional layer had a thickness of 2 μm, the core layer had a thickness of 17 μm, and the surface layer had a thickness of 1 μm. During the preparation process, the winding and unwinding was not smooth, and there was a situation of roller sticking.

[0092] A double-stretched polypropylene-based film of the present comparative example was coated with an adhesive on the surface layer to form an adhesive layer with a thickness of 5 μm, thereby obtaining an adhesive tape film. During the preparation process, the winding and unwinding was smooth.

[0093] Comparative Example 3

[0094] The present comparative example provides a double-stretched polypropylene-based film including a release functional layer, a core layer, and a surface layer arranged in sequence. The preparation method of the double-stretched polypropylene-based film of the present comparative example includes the following steps:

[0095] Preparation of the release functional layer resin: 73 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 18 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (the ethylene-norbornene copolymer segment is connected by 2 ethylene-norbornene copolymer units, and the fluorine-containing polysiloxane copolymer segment is connected by 3 fluorine-containing siloxane copolymer units), and 1 wt% of anti-blocking agent were uniformly mixed to obtain the release functional layer resin.

[0096] Preparation of the core layer resin: 99 wt% of homopolymer polypropylene and 1 wt% of antistatic agent were uniformly mixed to obtain the core layer resin.

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

[0098] The preparation method of the biaxially stretched polypropylene-based film of the present comparative example was the same as that of Example 1, and thus will not be described here.

[0099] The biaxially stretched polypropylene-based film of the present comparative example had a thickness of 20 μm, wherein the release functional layer had a thickness of 2 μm, the core layer had a thickness of 17 μm, and the surface layer had a thickness of 1 μm. During the preparation process, the winding and unwinding were smooth.

[0100] A biaxially stretched polypropylene-based film was obtained by coating a layer of adhesive on the surface layer of the biaxially stretched polypropylene-based film of the present comparative example to form an adhesive layer with a thickness of 5 μm. During the preparation process, the winding and unwinding were not smooth enough.

[0101] Comparative Example 4

[0102] The present comparative example provided a biaxially stretched polypropylene-based film, which comprised a release functional layer, a core layer, and a surface layer arranged in sequence. The preparation method of the resin of each layer of the biaxially stretched polypropylene-based film of the present comparative example comprised the following steps:

[0103] Preparation of the release functional layer resin: 59 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 32 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (the ethylene-norbornene copolymer segment is connected by 2 ethylene-norbornene copolymer units, and the fluorine-containing polysiloxane copolymer segment is connected by 3 fluorine-containing siloxane copolymer units), and 1 wt% of anti-blocking agent were uniformly mixed to obtain the release functional layer resin.

[0104] Preparation of the core layer resin: 99 wt% of homopolymer polypropylene and 1 wt% of antistatic agent were uniformly mixed to obtain the core layer resin.

[0105] Surface layer resin preparation: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content 30 wt%, number average molecular weight Mn 21000 g / mol, melting point Tm 95 °C) and 1 wt% crosslinked PMMA microparticles were uniformly mixed to obtain the surface layer resin.

[0106] The preparation method of the biaxially stretched polypropylene-based film of the present comparative example was the same as that of Example 1, and thus will not be described again.

[0107] The biaxially stretched polypropylene-based film had a thickness of 20 μm, wherein the thickness of the release functional layer was 2 μm, the thickness of the core layer was 17 μm, and the thickness of the surface layer was 1 μm. During the preparation process, the production smoothness was poor, and it was difficult to stretch into a film.

[0108] A biaxially stretched polypropylene-based film was obtained by coating an adhesive layer with a thickness of 5 μm on the surface layer of the biaxially stretched polypropylene-based film of the present comparative example to form an adhesive layer. During the preparation process, the unwinding and winding were smooth.

[0109] Comparative Example 5

[0110] The present comparative example provided a biaxially stretched polypropylene-based film, which included a release functional layer, a core layer and a surface layer arranged in sequence. The preparation method of the resin of each layer of the biaxially stretched polypropylene-based film of the present comparative example included the following steps:

[0111] Release functional layer resin preparation: 66 wt% homopolymerized polypropylene, 8 wt% ethylene-propylene copolymerized polypropylene, 25 wt% fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment connected by 2 ethylene-norbornene copolymer units, fluorine-containing polysiloxane copolymer segment connected by 3 fluorine-containing siloxane copolymer units) and 1 wt% anti-blocking agent were uniformly mixed to obtain the release functional layer resin.

[0112] Core layer resin preparation: 99 wt% homopolymerized polypropylene and 1 wt% antistatic agent were uniformly mixed to obtain the core layer resin.

[0113] Surface layer resin preparation: 84 wt% ethylene-propylene copolymerized polypropylene, 15 wt% ethylene-vinyl acetate copolymer (vinyl acetate (VA) content 20 wt%, melt index of the ethylene-vinyl acetate copolymer measured at 230 °C under a load of 2.16 kg was 15 g / 10 min, melting point Tm 85 °C) and 1 wt% crosslinked PMMA microparticles were uniformly mixed to obtain the surface layer resin.

[0114] The preparation method of the biaxially stretched polypropylene-based film of the present comparative example was the same as that of Example 1, and thus will not be described again.

[0115] The biaxially-stretched polypropylene-based film of the present comparative example has a thickness of 20 μm, wherein the thickness of the release functional layer is 2 μm, the thickness of the core layer is 17 μm, and the thickness of the surface layer is 1 μm. During the preparation process, the production smoothness is good.

[0116] A biaxially-stretched polypropylene-based film of the present comparative example is coated with an adhesive on the surface layer to form an adhesive layer with a thickness of 5 μm, thereby obtaining an adhesive tape film. During the preparation process, the unwinding and winding are not smooth enough, and there is a phenomenon of adhesive tape film peeling off.

[0117] Comparative Example 6

[0118] The present comparative example provides a biaxially-stretched polypropylene-based film, which comprises a release functional layer, a core layer, and a surface layer arranged in sequence. The preparation method of the resins of the respective layers of the biaxially-stretched polypropylene-based film of the present comparative example comprises the following steps:

[0119] Preparation of the release functional layer resin: 66 wt% of homopolymerized polypropylene, 8 wt% of ethylene-propylene copolymerized polypropylene, 25 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (the ethylene-norbornene copolymer segment is connected by 2 ethylene-norbornene copolymer units, and the fluorine-containing polysiloxane copolymer segment is connected by 3 fluorine-containing siloxane copolymer units), and 1 wt% of anti-blocking agent are uniformly mixed to obtain the release functional layer resin.

[0120] Preparation of the core layer resin: 99 wt% of homopolymerized polypropylene and 1 wt% of antistatic agent are uniformly mixed to obtain the core layer resin.

[0121] Preparation of the surface layer resin: 84 wt% of ethylene-propylene copolymerized polypropylene, 15 wt% of polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content is 50 wt%, number average molecular weight Mn is 21000 g / mol, and melting point Tm is 95 °C), and 1 wt% of crosslinked PMMA microparticles are uniformly mixed to obtain the surface layer resin.

[0122] The preparation method of the biaxially-stretched polypropylene-based film of the present comparative example is the same as that of Example 1, and thus a detailed description is omitted.

[0123] The biaxially-stretched polypropylene-based film of the present comparative example has a thickness of 20 μm, wherein the thickness of the release functional layer is 2 μm, the thickness of the core layer is 17 μm, and the thickness of the surface layer is 1 μm. During the preparation process, the production smoothness is poor, and there is a situation of roller sticking.

[0124] A biaxially-stretched polypropylene-based film of the present comparative example is coated with an adhesive on the surface layer to form an adhesive layer with a thickness of 5 μm, thereby obtaining an adhesive tape film. During the preparation process, the unwinding and winding are not smooth enough.

[0125] Comparative Example 7

[0126] The comparative example 2 provides a biaxially stretched polypropylene-based film including a release functional layer, a core layer and a surface layer arranged in sequence. The preparation method of the biaxially stretched polypropylene-based film of the comparative example 2 includes the following steps:

[0127] Preparation of the release functional layer resin: 66 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 25 wt% of a blend of fluorine-containing polysiloxane and ethylene-norbornene copolymer (the blend molar ratio of fluorine-containing polysiloxane and ethylene-norbornene copolymer is 3:2, and the melt index of the blend is 60 g / 10 min (test conditions: 190°C, 2.16 kg)), and 1 wt% of an anti-blocking agent are uniformly mixed to obtain the release functional layer resin.

[0128] Preparation of the core layer resin: 99 wt% of homopolymer polypropylene and 1 wt% of an antistatic agent are uniformly mixed to obtain the core layer resin.

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

[0130] The preparation method of the biaxially stretched polypropylene-based film of the comparative example 2 is the same as that of the example 1, and thus a repeated description is omitted.

[0131] The biaxially stretched polypropylene-based film has a thickness of 20 μm, in 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. In the preparation process, the production is smooth and good.

[0132] A biaxially stretched polypropylene-based film is prepared by coating a layer of adhesive on the surface layer of the biaxially stretched polypropylene-based film of the comparative example 2 to form an adhesive layer having a thickness of 5 μm, thereby obtaining an adhesive film. In the preparation process, the unwinding and winding are not smooth enough.

[0133] Comparative example 8

[0134] The comparative example 3 provides a biaxially stretched polypropylene-based film including a release functional layer, a core layer and a surface layer arranged in sequence. The preparation method of the biaxially stretched polypropylene-based film of the comparative example 3 includes the following steps:

[0135] Preparation of the release functional layer resin: 66 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 25 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (the ethylene-norbornene copolymer segment is connected by 3 ethylene-norbornene copolymer units, and the fluorine-containing polysiloxane copolymer segment is connected by 3 fluorine-containing siloxane copolymer units), and 1 wt% of an anti-blocking agent are uniformly mixed to obtain the release functional layer resin.

[0136] Core layer resin preparation: 99 wt% of homopolymer polypropylene and 1 wt% of antistatic agent were mixed uniformly to obtain the core layer resin.

[0137] Surface layer resin preparation: 84 wt% of ethylene-propylene copolymer polypropylene, 15 wt% of polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content of 30 wt%, number average molecular weight Mn of 21000 g / mol, and melting point Tm of 95 °C), and 1 wt% of crosslinked PMMA microparticles were mixed uniformly to obtain the surface layer resin.

[0138] The preparation method of the biaxially stretched polypropylene-based film of the present comparative example was the same as that of Example 1, and thus a detailed description thereof will not be given.

[0139] The biaxially stretched polypropylene-based film of the present comparative example had a thickness of 20 μm, in which the release functional layer had a thickness of 2 μm, the core layer had a thickness of 17 μm, and the surface layer had a thickness of 1 μm. During the preparation process, the production smoothness was poor, and the biaxial stretching film formation was difficult.

[0140] A biaxially stretched polypropylene-based film was obtained by coating an adhesive layer having a thickness of 5 μm on the surface layer of the biaxially stretched polypropylene-based film of the present comparative example. During the preparation process, the unwinding and winding were smooth.

[0141] Comparative Example 9

[0142] The present comparative example provides a biaxially stretched polypropylene-based film including a release functional layer, a core layer, and a surface layer, which are sequentially disposed. The preparation method of the resin of each layer of the biaxially stretched polypropylene-based film of the present comparative example includes the following steps.

[0143] Release functional layer resin preparation: 66 wt% of homopolymer polypropylene, 8 wt% of ethylene-propylene copolymer polypropylene, 25 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (ethylene-norbornene copolymer segment connected by 2 ethylene-norbornene copolymer units, and fluorine-containing polysiloxane copolymer segment connected by 1 fluorine-containing siloxane copolymer unit), and 1 wt% of anti-blocking agent were mixed uniformly to obtain the release functional layer resin.

[0144] Core layer resin preparation: 99 wt% of homopolymer polypropylene and 1 wt% of antistatic agent were mixed uniformly to obtain the core layer resin.

[0145] Surface layer resin preparation: 84 wt% of ethylene-propylene copolymer polypropylene, 15 wt% of polymethyl methacrylate grafted ethylene-vinyl acetate copolymer (PMMA content of 30 wt%, number average molecular weight Mn of 21000 g / mol, and melting point Tm of 95 °C), and 1 wt% of crosslinked PMMA microparticles were mixed uniformly to obtain the surface layer resin.

[0146] The preparation method of the biaxially stretched polypropylene-based film of the present comparative example was the same as that of Example 1, and thus a detailed description thereof will not be given.

[0147] The biaxially-stretched polypropylene-based film of the present comparative example has a thickness of 20 μm, wherein the thickness of the release functional layer is 2 μm, the thickness of the core layer is 17 μm, and the thickness of the surface layer is 1 μm. During the preparation process, the winding and unwinding is not smooth enough.

[0148] A biaxially-stretched polypropylene-based film of the present comparative example is obtained by coating a layer of adhesive on the surface layer to form a 5 μm thick adhesive layer. During the preparation process, the winding and unwinding is not smooth enough.

[0149] Comparative Example 10

[0150] The biaxially-stretched polypropylene-based film of the present comparative example comprises a release functional layer, a core layer and a surface layer arranged in sequence. The preparation method of the resins of the respective layers of the biaxially-stretched polypropylene-based film of the present comparative example comprises the following steps:

[0151] Preparation of the release functional layer resin: 66 wt% of homopolymerized polypropylene, 8 wt% of ethylene-propylene copolymerized polypropylene, 25 wt% of fluorine-containing polysiloxane functionalized ethylene-norbornene block copolymer (the ethylene-norbornene copolymer segment is connected by 2 ethylene-norbornene copolymer units, and the fluorine-containing polysiloxane copolymer segment is connected by 5 fluorine-containing siloxane copolymer units), and 1 wt% of anti-blocking agent are uniformly mixed to obtain the release functional layer resin.

[0152] Preparation of the core layer resin: 99 wt% of homopolymerized polypropylene and 1 wt% of antistatic agent are uniformly mixed to obtain the core layer resin.

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

[0154] The preparation method of the biaxially-stretched polypropylene-based film of the present comparative example is the same as that of Example 1, and thus is not described herein.

[0155] The biaxially-stretched polypropylene-based film of the present comparative example has a thickness of 20 μm, wherein the thickness of the release functional layer is 2 μm, the thickness of the core layer is 17 μm, and the thickness of the surface layer is 1 μm. During the preparation process, the winding and unwinding is smooth.

[0156] A biaxially-stretched polypropylene-based film of the present comparative example is obtained by coating a layer of adhesive on the surface layer to form a 5 μm thick adhesive layer. During the preparation process, the winding and unwinding is smooth.

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

[0158] Table 1

[0159]

[0160] From the performance test data above, it can be seen that:

[0161] The biaxially oriented polypropylene-based film of Examples 1-3, on the one hand, has a release function layer with a relatively low peeling force, and without coating silicone oil, the surface layer and the adhesive layer can not be adhered to the release function layer when unwinding, realizing the smoothness of the adhesive film and the biaxially oriented polypropylene-based film when winding and unwinding, and improving the barrier property of the release function layer, which is conducive to maintaining the adhesion between the adhesive layer and the substrate in a high-humidity environment, and can be used in a high-humidity environment for a long time. On the other hand, the surface layer has a relatively high peeling force, and without coating a primer, the surface layer and the adhesive layer can produce good adhesion, which is conducive to ensuring that the adhesive layer does not separate from the surface layer when unwinding, and can be easily torn off after use for repeated use. In addition, the addition of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer also improves the barrier property of the release function layer, which is conducive to maintaining the high adhesion of the adhesive film in a high-humidity environment under the synergistic effect of the enhanced peeling force of the surface layer, and can be used in a high-humidity environment for a long time.

[0162] According to the data of Comparative Example 1 and Example 2, under the same conditions of the release function 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 that of Example 2, which is not conducive to effectively ensuring the adhesion between the surface layer and the adhesive layer of the adhesive film, and there is a risk of delamination. It is also not conducive to use in a high-humidity environment.

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

[0164] According to the data of Comparative Example 3 and Example 2, under the same conditions of the surface layer, the content of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer in the release function layer of Comparative Example 3 is too low, and the release effect is not obvious. The peeling force of the release function layer of Comparative Example 3 is significantly higher than that of Example 2, which is not conducive to the detachment of the adhesive layer and the release function layer, and the prepared adhesive film has the problem of not being smooth enough when winding and unwinding. In addition, the low content of fluorinated polysiloxane functionalized ethylene-norbornene block copolymer leads to a decrease in the barrier property of the release function layer, and the peeling force of the surface layer of Comparative Example 3 is also slightly lower than that of 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 the fluorosilicone functionalized ethylene-norbornene block copolymer in the release function layer of Comparative Example 4 is too high, and the release force of the release function layer of Comparative Example 4 is obviously lower than that of Example 2, but the biaxially stretched polypropylene-based 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 an unmodified ethylene-vinyl acetate copolymer without grafting polymethyl methacrylate, and the adhesion effect is not as good as that of the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer, and the surface layer release force of Comparative Example 5 is obviously lower than that of Example 2, which is not conducive to effectively ensuring the bonding force between the surface layer and the adhesive layer of the adhesive tape film, and there is a risk of delamination, and it is also not conducive to application in high humidity environments.

[0167] According to the data of Comparative Example 6 and Example 2, the content of PMMA in the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer of Comparative Example 6 is too high, although the surface layer release force of Comparative Example 6 is obviously higher than that of Example 2, but the surface layer of the biaxially stretched polypropylene-based film of Comparative Example 6 is too sticky, and the film-forming properties during production are poor, and it cannot be smoothly produced.

[0168] According to the data of Comparative Example 7 and Example 2, Comparative Example 7 adds a blend of fluorosilicone and ethylene-norbornene copolymer to the release function layer, and the compatibility and uniformity of the blend in the release function layer will be poorer than that of the fluorosilicone functionalized ethylene-norbornene block copolymer, and the release force of the release function layer of Comparative Example 7 is slightly lower than that of Example 2, and the BOPP-based film of Comparative Example 7 has bright spots on the surface.

[0169] According to the data of Comparative Example 8 and Example 2, the number of ethylene-norbornene copolymer units constituting the ethylene-norbornene segment in the release function layer of Comparative Example 8 is too high, the release force of the release function layer of Comparative Example 8 is lower than that of Example 2, and due to the improvement of the barrier property, the release force of the surface layer is greater than that of Example 2, but Comparative Example 8 has a problem of difficult stretching 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 content of fluorosilicone in the fluorosilicone constituting the fluorosilicone segment of Comparative Example 9 is too low, and the release effect is not obvious, the release force of the release function layer of Comparative Example 9 is obviously higher than that of Example 2, which is not conducive to the detachment of the adhesive layer and the release function layer, and the prepared adhesive tape film has the problem of not being smooth enough during unwinding and winding, and it is also not conducive to the smoothness of the BOPP-based film itself during unwinding and winding.

[0171] According to the data of Comparative Example 10 and Example 2, the fluorosilicone in the release function layer of Comparative Example 10 is too much to form a fluorosilicone segment, and its compatibility and dispersion uniformity in the release function layer are worse than those of the fluorosilicone functionalized ethylene norbornene block copolymer. Although the release force of the release function layer of Comparative Example 10 is lower than that of the release function layer of Example 2, the BOPP base film surface of Comparative Example 10 has bright spots, which is not conducive to the uniformity of the release.

[0172] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, and the present application also intends to include these modifications and improvements.

Claims

1. A biaxially stretched polypropylene-based film, characterized in that, The release function layer, the core layer and the surface layer are sequentially arranged; the release function layer comprises homopolymer polypropylene, 5-10wt% ethylene-propylene copolymerized polypropylene and 20-30wt% fluorosilicone functionalized ethylene-norbornene block copolymer, the fluorosilicone functionalized ethylene-norbornene block copolymer is copolymerized by fluorosilicone segments and ethylene-norbornene segments, the fluorosilicone segments are copolymerized by 3-4 fluorosilicone units, and the ethylene-norbornene segments are copolymerized by 1-2 ethylene-norbornene units; the core layer comprises homopolymer polypropylene; and the surface layer comprises ethylene-propylene copolymerized polypropylene and 10-20wt% polymethyl methacrylate grafted ethylene-vinyl acetate copolymer, the content of polymethyl methacrylate in the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 20-40wt%.

2. The biaxially-stretched polypropylene-based film according to claim 1, characterized in that, The surface layer further comprises 0.5-1wt% crosslinked polymethyl methacrylate microparticles.

3. The biaxially oriented polypropylene-based film according to claim 1, wherein, The melt index of the fluorosilicone functionalized ethylene-norbornene block copolymer is 50-100g / 10min measured at 190℃ under a load of 2.16kg.

4. The biaxially oriented polypropylene-based film according to claim 1, wherein The number average molecular weight of the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 20000-22000g / mol.

5. The biaxially oriented polypropylene-based film according to claim 1, wherein, The melting point of the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 90-100℃.

6. The biaxially oriented polypropylene-based film according to claim 1, wherein, The melting point of the ethylene-vinyl acetate copolymer in the polymethyl methacrylate grafted ethylene-vinyl acetate copolymer is 80-90℃, and the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 15-25wt%.

7. The biaxially oriented polypropylene-based film according to claim 1, wherein The thickness of the release function layer is 1-2μm, the thickness of the surface layer is 1-2μm, and the thickness of the biaxially stretched polypropylene-based film is 12-25μm.

8. A process for producing a biaxially stretched polypropylene-based film as claimed in any one of claims 1 to 7, characterized in that, The surface layer, the core layer and the release function layer are co-extruded and cooled to form a resin sheet; and the resin sheet is longitudinally stretched and transversely stretched; The surface layer is subjected to corona treatment and winding, the extrusion temperature of the surface layer and the core layer is 220-260℃, and the extrusion temperature of the release function layer is 200-250℃.

9. A tape film comprising the biaxially stretched polypropylene-based film according to any one of claims 1 to 7, characterized in that, The adhesive layer is further arranged, and the release function layer, the core layer, the surface layer and the adhesive layer are sequentially arranged.

10. The tape film of claim 9, wherein, The adhesive layer comprises at least one of acrylic resin, water-based acrylate adhesive and vinyl acetate resin.

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