BOPET (Biaxially Oriented Polyethylene Terephthalate) non-silicon release film with high residual rejection rate and adjustable release force and preparation method of BOPET non-silicon release film

Abstract

The invention provides a BOPET (Biaxially Oriented Polyethylene Terephthalate) non-silicon release film with high residual rejection rate and adjustable release force and a preparation method of the BOPET non-silicon release film. The BOPET non-silicon release film with the high residual rejection rate and the adjustable release force comprises a BOPET base film and a non-silicon release layer located on at least one side of the BOPET base film. The preparation method comprises the following steps: adding corona and on-line coating procedures between longitudinal stretching and transverse stretching in the process of producing the BOPET film by a direct melting method so as to form a non-silicon release layer on the surface of at least one side of a longitudinal stretching product, and then sequentially carrying out a series of procedures of transverse preheating, stretching, curing and shaping, and traction and rolling to obtain the BOPET non-silicon release film. The BOPET non-silicon release film provided by the invention has the advantages of uniform coating thickness, stable release performance after long-term placement, high residual adhesion rate, low aging, simple production process, high production yield per unit time and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of non-silicon release films, and in particular to a BOPET non-silicon release film with high residual interception rate and adjustable release force and a preparation method thereof. Background Art

[0002] Release films are widely used in pressure-sensitive adhesive labels, car cover TPU protective films, waterproof materials, electronic products, medicine and other fields because of their low surface tension and weak adhesion after contact with specific materials under limited conditions. In addition, the release films currently sold on the market are mainly based on silicone oil and fluorine elements, and silicone oil release films will undergo trace silicon transfer when used. In addition, some special electronic products used in high-end fields are extremely sensitive to silicon and fluorine elements. Silicon elements can easily lead to poor processing and short circuit risks of electronic products, but in the preparation process of electronic products, suitable protective film materials must be used to protect them, that is, non-silicone release films. Secondly, as an environmentally friendly and highly customizable modern material, non-silicone release films are also widely used in processes such as coating, printing and bonding to avoid silicone oil residue problems. It is suitable for high-cleanliness surface treatment industries such as electronics and automobiles to ensure product quality. The environmental protection characteristics and customization capabilities of non-silicone release films give it broad application prospects in the field of high-end manufacturing.

[0003] The existing non-silicone release film production is mostly offline production with solvent-based coating liquid directly coated on the substrate. The non-silicone release film products produced have many problems such as thick coating, high cost, low production capacity, poor appearance and low coating residue. In addition, the excessive use of volatile solvents in the coating liquid during the production process has a great harm to the environment and personnel health. In addition, there is currently no mature process conditions for online stable production of non-silicone offline coating release films in China.

[0004] Therefore, it is of great significance to study a BOPET non-silicone release film and a preparation method that can be stably produced online with a high residual retention rate and adjustable release force, so as to solve the problems of poor coating appearance, high cost, low residue and low production efficiency of non-silicone release films in the prior art. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is that the non-silicon release film in the prior art cannot be stably produced online, has a low residual retention rate, a high aging rate, a poor coating appearance and a high production cost.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides a BOPET non-silicon release film with high residual retention rate and adjustable release force and a preparation method thereof.

[0009] In a first aspect, the present invention provides a BOPET non-silicone release film with high residual retention rate and adjustable release force, comprising a BOPET base film, and a non-silicone release layer coated on at least one surface of the BOPET base film;

[0010] Furthermore, the coating liquid of the non-silicone release layer is composed of 50%-75% modified polyolefin water-based resin, 0.05%-0.2% acetylene alcohol leveling agent, 0.06%-0.08% defoaming agent, 8%-12% isopropyl alcohol, and the balance is water.

[0011] Furthermore, the thickness of the BOPET base film is 15-50 μm, and the thickness of the non-silicon release layer is 70-140 nm.

[0012] The present invention also provides a modified polyolefin water-based resin, comprising the following components in percentage by mass:

[0013] Modified polyethylene water-based emulsion 55-65%

[0014] 2-Propanol 2%-5%

[0015] Dimethylaminoethanolamine 0.5-1.2%

[0016] Water 30%~42%

[0017] Furthermore, the solid content of the coating liquid of the non-silicon release layer is 20-30%.

[0018] Furthermore, the modified polyethylene aqueous emulsion is at least one of an acrylate-grafted modified linear low-density polyethylene aqueous emulsion and an acrylate-grafted modified low molecular weight polyethylene aqueous emulsion.

[0019] Furthermore, the acetylene alcohol leveling agent is selected from at least one of acetylene glycol ethylene oxide and ethoxyacetylene glycol.

[0020] Furthermore, the defoaming agent is selected from at least one of TY-500, BYK-016, HR-3074, and fatty alcohol defoaming agent KS118.

[0021] On the other hand, the present invention also provides a method for preparing a BOPET non-silicon release film with high residual retention rate and adjustable release force, comprising the steps of:

[0022] S1. Preparation of a non-silicone release layer coating liquid: adding isopropyl alcohol, an acetylenic alcohol leveling agent, a defoaming agent, and water to a modified polyolefin water-based resin, and mixing to obtain a non-silicone release layer coating liquid;

[0023] S2. coating the non-silicon release layer coating liquid on at least one surface of the BOPET base film to prepare a BOPET non-silicon release film having a non-silicon release layer.

[0024] Furthermore, the step S2 includes:

[0025] The PET resin is melted, extruded into a cast sheet, and then longitudinally stretched to obtain a longitudinally stretched film;

[0026] Performing corona treatment on the longitudinally stretched film, and then coating the non-silicone release layer coating liquid online;

[0027] Afterwards, the film is stretched transversely and then rolled up to obtain a BOPET non-silicone release film;

[0028] Furthermore, during online coating, the temperature of the coating machine is 21±2°C, the coating liquid temperature is 25-30°C, the pressure of the pressure roller is 5±0.2MPa, and the coating liquid amount is 1.8-3.5g / m 2 .

[0029] Furthermore, the online coating method is micro-gravure coating, and the coating liquid temperature is 25-30°C.

[0030] Furthermore, the process parameters include: main / auxiliary extruder temperature of 265-285°C; casting roller temperature of 25±1°C; longitudinal stretching temperature of 80-110°C, stretching ratio of 3.2-4.0; corona machine voltage of 15±0.5kV, speed ratio of 0±0.1.

[0031] Furthermore, the transverse stretching temperature is 110-120° C., the setting temperature is 195-248° C., and the stretching ratio is 3.8-4.5.

[0032] Furthermore, the BOPET base film produced by the method has a thickness of 15 to 50 μm, a production speed of 100 to 400 m / min, a haze of ≤4%, a thickness of the non-silicon release layer of 70 to 140 nm, and a release force of 15 to 60 g / in.

[0033] The present invention also provides a BOPET non-silicon release film with high residual interception rate and adjustable release force for use in pressure-sensitive adhesive labels, car cover protective films, waterproof protective films, and electronic protective films.

[0034] (III) Beneficial effects

[0035] The above technical solution of the present invention has the following advantages:

[0036] 1. Low cost and good quality: The base material used for the release film is melt-direct melting, and this process reduces the cost of raw material transportation and secondary melting. In addition, the elimination of the above two processes greatly reduces the pollution caused by the raw material transportation process and the viscosity drop caused by secondary melting. The non-silicon release film produced by this method has less oligomers, high film surface cleanliness and strong thermal stability.

[0037] 2. High residual force, low aging, and wide adjustable release force range: After multiple optimizations of the formula, the release force of this project can be stably adjusted between 15-70g / in to meet the different peeling ranges of different customers; the aging release force is low and the surface of the composite release layer is smooth and stable, which greatly reduces the phenomenon of poor peeling after customers' glue coating; in addition, the non-silicone release film produced by this formula has a high residual retention rate (≥95%) and a stable coating.

[0038] 3. Large production capacity and high efficiency: Currently, all non-silicone release films sold on the market adopt an offline coating process, which is restricted by the production capacity of the coating equipment and the drying capacity of the oven, and has low production efficiency. The present invention draws on the experience of online silicone release film production and optimizes the process, making full use of the large space size and high air supply and exhaust power of the transversely stretched oven, and has a fast production speed. The production capacity efficiency of the online non-silicone release film produced is much higher than that of the offline secondary coating process. DETAILED DESCRIPTION

[0039] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0040] A BOPET non-silicon release film with high residual retention rate and adjustable release force comprises a BOPET base film and a non-silicon release layer coated on at least one surface of the BOPET base film.

[0041] As a preferred embodiment of the present invention, the coating liquid of the non-silicone release layer is composed of 50%-75% modified polyolefin water-based resin, 0.05%-0.2% acetylene alcohol leveling agent, 0.06%-0.08% defoaming agent, 8%-12% isopropyl alcohol, and the balance is water.

[0042] As a preferred embodiment of the present invention, the thickness of the BOPET base film is 15-50 μm, and the thickness of the non-silicon release layer is 70-140 nm. The present invention can achieve a release force that is stable and adjustable in the range of 15-60 g / in and a residual bonding rate of >95% by adjusting the coating thickness and optimizing the formula.

[0043] The present invention also provides a modified polyolefin water-based resin, comprising the following components in percentage by mass:

[0044]

[0045] As a preferred embodiment of the present invention, the solid content of the coating liquid of the non-silicone release layer is 20-30%.

[0046] As a preferred embodiment of the present invention, the modified polyethylene aqueous emulsion is at least one of a linear low-density polyethylene aqueous emulsion modified by acrylate grafting and a low molecular weight polyethylene aqueous emulsion modified by acrylate grafting. The present invention improves the weather resistance, environmental protection and bonding strength of the material with the substrate by grafting and modifying low-density polyethylene or low molecular weight polyethylene.

[0047] As a preferred embodiment of the present invention, the acetylenic alcohol leveling agent is selected from at least one of acetylenic glycol ethylene oxide and ethoxyacetylenic glycol.

[0048] As a preferred embodiment of the present invention, the defoamer is selected from at least one of TY-500, BYK-016, HR-3074, and fatty alcohol defoamer KS118.

[0049] On the other hand, the present invention also provides a method for preparing a BOPET non-silicon release film with high residual retention rate and adjustable release force, comprising the steps of:

[0050] S1. Preparation of a non-silicone release layer coating liquid: adding isopropyl alcohol, an acetylenic alcohol leveling agent, a defoaming agent, and water to a modified polyolefin water-based resin, and mixing to obtain a non-silicone release layer coating liquid;

[0051] S2. coating the non-silicon release layer coating liquid on at least one surface of the BOPET base film to prepare a BOPET non-silicon release film having a non-silicon release layer.

[0052] As a preferred embodiment of the present invention, step S2 includes:

[0053] The PET resin is melted, extruded into a cast sheet, and then longitudinally stretched to obtain a longitudinally stretched film;

[0054] Performing corona treatment on the longitudinally stretched film, and then coating the non-silicone release layer coating liquid online;

[0055] Afterwards, the film is stretched transversely and then rolled up to obtain a BOPET non-silicone release film;

[0056] As a preferred embodiment of the present invention, during online coating, the temperature of the coating machine is 21±2°C, the coating liquid temperature is 25-30°C, the pressure of the pressure roller is 5±0.2MPa, and the coating liquid amount is 1.8-3.5g / m 2 .

[0057] As a preferred embodiment of the present invention, the online coating method is micro-gravure coating, and the coating liquid temperature is 25-30°C.

[0058] As a preferred embodiment of the present invention, the process parameters include: the main / auxiliary extruder temperature is 265-285°C; the casting roller temperature is 25±1°C; the longitudinal stretching temperature is 80-110°C, and the stretching ratio is 3.2-4.0; the corona machine voltage is 15±0.5kV, and the speed ratio is 0±0.1.

[0059] As a preferred embodiment of the present invention, the transverse stretching temperature is 110-120° C., the setting temperature is 195-248° C., and the stretching ratio is 3.8-4.5.

[0060] As a preferred embodiment of the present invention, the BOPET base film produced by the method has a thickness of 15 to 50 μm, a production speed of 100-400 m / min, a haze ≤ 4%, a non-silicon release layer thickness of 70-140 nm, and a release force of 15 to 60 g / in.

[0061] The raw materials used in the examples are all commercially available.

[0062] The acrylic ester grafted modified linear low-density polyethylene used has a viscosity of 4.57 MPa.s and a density of 18000-20000 kg / m3, and was purchased from Changzhou Sante Chemical.

[0063] Example 1

[0064] This embodiment provides a BOPET non-silicone release film with high residual and adjustable release force, comprising a BOPET base film and a non-silicone release layer coated on one surface of the BOPET base film.

[0065] The mass percentage composition of the coating liquid of the non-silicone release layer is:

[0066] Modified polyolefin water-based resin 63%,

[0067] Ethoxy acetylenediol leveling agent C07 0.13%,

[0068] Fatty alcohol defoamer KS118 0.065%,

[0069] Isopropyl alcohol C09 8.5%,

[0070] The balance is water.

[0071] The modified polyolefin water-based resin is composed of the following raw materials by mass fraction: 59% of acrylate grafted modified linear low-density polyethylene water-based emulsion, 2.5% of 2-propanol, 0.63% of dimethylaminoethanolamine, and 37.87% of solvent water. The density of acrylate grafted modified linear low-density polyethylene is 0.94g / ml. 3 .

[0072] The method for preparing a BOPET non-silicon release film with high residual and adjustable release force provided in this embodiment comprises the following specific steps:

[0073] Step 1, prepare the coating liquid: first weigh the modified polyolefin water-based resin and pour it into the liquid preparation barrel, start stirring at 400rpm / min; then add isopropyl alcohol C09, ethoxylated acetylene glycol leveling agent C07 and fatty alcohol defoamer KS118 mixed and diluted with water in a mass ratio of 1:1, and finally add water to adjust the solid content of the coating liquid to 17%. Continue stirring for 25 minutes and let it stand for 30 minutes to obtain the coating liquid of the non-silicone release layer.

[0074] Among them, the solvent water and dilution water used in the liquid preparation process are both treated pure water, and the operating temperature is 15°C.

[0075] Step 2, preparing a stable BOPET release film with high residual weight release force produced online, the overall process flow is: resin melting → extrusion casting → longitudinal stretching → corona treatment → online coating → transverse stretching → online dust removal → traction and winding → slitting and packaging;

[0076] The specific process parameters include: the average thickness of the BOPET base film is 50μm; the temperature of the main / auxiliary extruder is 278℃; the temperature of the casting roll is 25±1℃; the longitudinal stretching temperature is 92.3℃, and the stretching ratio is 3.2; the corona machine voltage is 15±0.5kV, and the speed ratio is 0±0.1%; the micro-concave coating process is used to apply the above-mentioned coating liquid on the single side surface of the longitudinally stretched product, the coating speed ratio is 23.7%, the coating machine temperature is 20±1℃, the pressure of the pressure roll is 5±0.2MPa, and the coating wet glue amount is 2.4g / m 2 ; The transverse stretching temperature is 116°C, the setting temperature is 240.5°C, the stretching ratio is 3.85; the winding speed is 120m / min.

[0077] The BOPET non-silicone release film with high residual and adjustable release force provided in Example 1 has an average thickness of 50 μm for the BOPET base film and a thickness limit deviation of 0.3 μm; an average thickness of the non-silicone release film coating is 0.13 μm and a thickness limit deviation of 0.02 μm;

[0078] The BOPET non-silicone release film provided in this embodiment has a 20-minute quick release force of 17.8 g / in, a 20-hour conventional release force of 21.3 g / in, a 20-hour aging release force of 45.8 g / in, and a residual bonding rate of 96.8%.

[0079] Example 2

[0080] This embodiment provides a BOPET non-silicone release film with high residual and adjustable release force, comprising a BOPET base film and a non-silicone release layer coated on one surface of the BOPET base film.

[0081] The mass percentage composition of the coating liquid of the non-silicone release layer is:

[0082] Modified polyolefin water-based resin 58%

[0083] Ethoxy acetylenediol leveling agent C07 0.15%

[0084] Fatty alcohol defoamer KS118 0.06%

[0085] Isopropyl alcohol C09 10%

[0086] The balance is water.

[0087] The modified polyolefin water-based resin is composed of the following raw materials by mass fraction: 56.3% of acrylate grafted modified linear low-density polyethylene water-based emulsion, 2.27% of 2-propanol, 0.75% of dimethylaminoethanolamine, and 40.68% of solvent water. The density of acrylate grafted modified linear low-density polyethylene is 0.98g / ml. 3 .

[0088] The method for preparing a BOPET non-silicon release film with high residual and adjustable release force provided in this embodiment comprises the following specific steps:

[0089] Step 1, prepare the coating liquid: first weigh the modified polyolefin water-based resin and pour it into the liquid preparation barrel, start stirring at 400rpm / min; then add isopropyl alcohol C09, ethoxylated acetylene glycol leveling agent C07 and fatty alcohol defoaming agent KS118 mixed and diluted with water in a mass ratio of 1:1 in sequence, and finally add water to adjust the solid content of the coating liquid to 12%, continue stirring for 25 minutes, and let it stand for 30 minutes to obtain the coating liquid of the non-silicone release layer.

[0090] Among them, the solvent water and dilution water used in the liquid preparation process are both treated pure water, and the operating temperature is 15°C.

[0091] Step 2, preparing a stable BOPET release film with high residual weight release force produced online, the overall process flow is: resin melting → extrusion casting → longitudinal stretching → corona treatment → online coating → transverse stretching → online dust removal → traction and winding → slitting and packaging;

[0092] The specific process parameters include: the average thickness of the BOPET base film is 25μm; the temperature of the main / auxiliary extruder is 276℃; the temperature of the casting roll is 25±1℃; the longitudinal stretching temperature is 109.5℃, and the stretching ratio is 3.72; the corona machine voltage is 15±0.5kV, and the speed ratio is 0±0.1%; the micro-concave coating process is used to apply the above-mentioned coating liquid on the single side surface of the longitudinally stretched product, the coating speed ratio is 25.2%, the coating machine temperature is 20±1℃, the pressure of the pressure roll is 5±0.2MPa, and the coating wet glue amount is 2.1g / m 2 ; The transverse stretching temperature is 117°C, the setting temperature is 243.5°C, the stretching ratio is 3.87; the winding speed is 216m / min.

[0093] The BOPET non-silicone release film with high residual and adjustable release force provided in Example 2 has an average BOPET base film thickness of 25 μm and a thickness limit deviation of 0.15 μm; the average thickness of the non-silicone release film coating is 0.08 μm and a thickness limit deviation of 0.01 μm.

[0094] The BOPET non-silicone release film provided in this embodiment has a 20-minute quick release force of 23.8 g / in, a 20-hour conventional release force of 35.4 g / in, a 20-hour aging release force of 46.7 g / in, and a residual bonding rate of 97.3%.

[0095] The test method involved in the specific implementation is as follows:

[0096] Release force test: 31B tape is attached to the non-silicone release film to be tested along the longitudinal (mechanical) direction. The sample is rolled back and forth twice with a standard FINAT test roller weighing 2kg to ensure that the tape and the sample are evenly attached. The blank standard sample is attached to the Teflon film in the above steps; the sample and the standard sample are cut into 200mm×30mm strips, and each sample requires at least 5 strips; the test strips and the standard sample are pressed flat between two standard stainless steel pressure strips, with a load of 20g / cm2.

[0097] For the rapid release force test, the specimen is placed at room temperature for 20 minutes. After the specimen is taken out and the load is removed, a peeling force tester can be used to perform a peeling test at an angle of 180° and a speed of 30 cm / min. The unit is g / in.

[0098] For conventional release force test, the specimen is placed at room temperature for 20 hours, then taken out, the load is removed, and placed in a standard environment for 2 hours before the peeling test can be performed under the above conditions;

[0099] For the aging release force test, the specimens were placed in an oven at 70°C for 20 hours, and the remaining steps were the same as those for the conventional peeling force test.

[0100] Residual bonding rate (i.e., residual bonding rate) test: The sample strips and standard samples prepared in the above steps are pressed flat with a pressing block at the same time, placed in a 70°C oven for 20 hours, taken out, the load is removed, and placed in a standard environment for 2 hours; the 31B tape is peeled off from the sample strips, maintaining a uniform speed, and at the same time, it is attached to the non-corona surface of the blank PET film in the longitudinal direction, and the sample is rolled back and forth twice with a standard FINAT test roller to ensure that the tape and the sample are flat; then the standard sample is peeled off from the Teflon film, and a standard blank standard sample is made according to the above steps; after placing for 2 hours, a peeling force test is performed, and the residual bonding rate is the ratio of the peeling force of the sample test to the peeling force of the blank standard test.

[0101] Ordinary products on the market: This non-silicone release film is produced offline. Compared with the online non-silicone release film production, this process requires the purchase of the base film and then rewinding and coating. Its production cost is high, efficiency is low, and the coating is thick and the uniformity is poor. Its product structure is the same as the online non-silicone release film, that is, the BOPET base film and the non-silicone release layer coated on at least one surface of the substrate.

[0102] The following is a comparison of data of Examples 1 and 2 of the present invention with common commercial products, see the table below for details.

[0103] Table 1 Performance comparison of various release films

[0104]

[0105] It can be seen from the above table that the present invention has lower quick peeling force, conventional peeling force and aging peeling force than ordinary products on the market, and has excellent residual bonding rate. The surface of the composite release layer is smooth and stable, which reduces the phenomenon of poor peeling after customers' glue coating. In addition, the non-silicone release film produced by this formula has a high residual retention rate (≥95%) and a stable coating.

[0106] It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In addition, for the sake of simplicity, detailed descriptions of known methods and technologies are omitted here.

[0107] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A BOPET non-silicone release film with high residual retention rate and adjustable release force, characterized in that: It includes a BOPET base film, and a non-silicon release layer coated on at least one surface of the BOPET base film; The coating liquid of the non-silicone release layer is composed of 50%-75% of modified polyolefin water-based resin, 0.05%-0.2% of acetylene alcohol leveling agent, 0.06%-0.08% of defoaming agent, 8%-12% of isopropyl alcohol, and the balance is water.

2. The BOPET non-silicone release film according to claim 1, characterized in that: The thickness of the BOPET base film is 15-50 μm, and the thickness of the non-silicon release layer is 70-140 nm.

3. The BOPET non-silicone release film according to claim 1, characterized in that: The modified polyolefin water-based resin comprises the following components in percentage by mass:

4. The BOPET non-silicone release film according to claim 1, characterized in that: The solid content of the coating liquid of the non-silicon release layer is 20-30%.

5. The BOPET non-silicone release film according to claim 3, characterized in that: The modified polyethylene aqueous emulsion is at least one of an acrylate-grafted modified linear low-density polyethylene aqueous emulsion and an acrylate-grafted modified low-molecular-weight polyethylene aqueous emulsion.

6. The BOPET non-silicone release film according to claim 1, characterized in that: The acetylene alcohol leveling agent is selected from at least one of acetylene glycol ethylene oxide and ethoxyacetylene glycol.

7. The BOPET non-silicone release film according to claim 1, characterized in that: The defoamer is selected from at least one of TY-500, BYK-016, HR-3074, and fatty alcohol defoamer KS118.

8. A method for preparing the BOPET non-silicon release film according to any one of claims 1 to 7, characterized in that: Includes steps: S1. Preparation of a non-silicone release layer coating liquid: adding isopropyl alcohol, an acetylenic alcohol leveling agent, a defoaming agent, and water to a modified polyolefin water-based resin, and mixing to obtain a non-silicone release layer coating liquid; S2. coating the non-silicon release layer coating liquid on at least one surface of the BOPET base film to prepare a BOPET non-silicon release film having a non-silicon release layer.

9. The method for preparing the BOPET non-silicon release film according to claim 8, characterized in that: Step S2 includes: The PET resin is melted, extruded into a cast sheet, and then longitudinally stretched to obtain a longitudinally stretched film; Performing corona treatment on the longitudinally stretched film, and then coating the non-silicone release layer coating liquid online; Afterwards, the film is stretched transversely and then rolled up to obtain a BOPET non-silicone release film; During online coating, the temperature of the coating machine is 21±2℃, the temperature of the coating liquid is 25-30℃, the pressure of the pressure roller is 5±0.2MPa, and the coating liquid amount is 1.8~3.5g / m 2 .

10. Application of the BOPET non-silicon release film according to any one of claims 1 to 7 in pressure-sensitive adhesive labels, car cover protective films, waterproof protective films, and electronic product protective films.

Images