A polyolefin release film and preparation method thereof and a preparation method of a roughened surface layer

Abstract

The present invention belongs to the technical field of waterproof materials, and relates to a polyolefin release film, a preparation method thereof, and a preparation method of a roughened surface layer. The release film comprises: a polyolefin polymer roughened surface layer and an organic polymer hardened isolation coating; the organic polymer hardened isolation coating is coated on at least one side of the roughened surface layer; the roughened surface layer comprises a polyolefin polymer and a micropowder material embedded therein, at least part of the micropowder material protrudes from the base film of the roughened surface layer, and the micropowder material has no physical state change below 240°C. The rough surface of the polyolefin release film of the present invention does not contain any foaming substances, rough granular substances, or sharp protruding structures, and does not cause any structural and performance damage to the substrate film; at the same time, the structure also solves the uniformity of the release coating, so that the release force of the polyolefin release film is uniform and stable and the residual joint is low, the release film is easier to separate from the coil and it is not easy to have asphalt residue after peeling, thereby improving the construction efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of waterproof materials, and more specifically, relates to a polyolefin release film and a preparation method thereof and a preparation method of a roughened surface layer. Background Art

[0002] Release film is an important "anti-sticking and isolation" functional material for self-adhesive modified asphalt waterproofing membrane. CN204020090U discloses a release film with an embossed structure. A series of semi-destructive convex points are selected in the film to buffer the residual local stress during the curling and storage of the asphalt membrane, so that the wrinkle state of the membrane surface layer is improved. However, this embossing is a sharp and soft convex structure. Under the action of pressure, it is very easy to embed in the asphalt self-adhesive layer, so that an anchoring structure is formed between the release film and the self-adhesive layer, which is difficult to tear off during construction. CN102666094A discloses a release film with protrusions formed on a base film and containing more than one cured product containing a photocurable resin composition. The protrusions of this structure are also easily embedded in the asphalt self-adhesive layer, making it difficult to tear off the film during construction. At the same time, due to the lack of a barrier layer, it cannot reduce the migration of small molecules in asphalt and glue, which greatly shortens the service life of the waterproof membrane.

[0003] After investigation, it is found that there is another technology that adds hollow microspheres that expand at a certain temperature to the base film, and uses at least one volatile organic compound in the hollow microspheres to achieve surface structure roughening. However, this process is difficult to control during implementation, and this "destructive" roughening method is very likely to destroy the structure of the release film itself.

[0004] In summary, there are currently three methods for roughening release films:

[0005] 1) A pressure roller with a certain texture structure is used to press at a certain temperature and pressure to achieve roughening of the surface of the base film.

[0006] 2) A composition containing a photocurable resin is used to form concave and convex points on the surface of the base film to roughen the surface.

[0007] 3) adding hollow microspheres that expand at a certain temperature, and using at least one volatile organic compound in the hollow microspheres to roughen the surface structure.

[0008] Through the above analysis, the above three release film roughening treatment methods cannot effectively solve the problem of effective separation of the release film from the coil, and may also damage the structure of the substrate film.

[0009] In order to solve the above problems, the present invention achieves roughening of the substrate surface by adding a high melting point organic-inorganic solid granular material to the polymer carrier and utilizing the different thermodynamic properties of the polymer carrier and the organic-inorganic solid granular material. The rough surface of the present invention does not contain the sharp protrusion structure in the embossed release film, but is a flat texture, which does not cause any structural and performance damage to the substrate film; at the same time, the structure also better solves the uniformity of the release coating, and the release force is uniform and stable. The release force of the polyolefin release film of the present invention is uniform and stable, and the residual connection is low. After long-term storage, the fluctuation of the release force is <10%, which makes the release film easier to separate from the roll material and it is not easy to have asphalt residue after peeling, thereby improving the construction efficiency. Furthermore, the waterproof roll material with the polyolefin release film has an excellent self-adhesiveness retention rate, and the viscosity retention rate is above 85% after accelerated aging at 70°C for 7 days. Summary of the invention

[0010] In view of the deficiencies in the prior art, the present invention provides a polyolefin release film, the rough surface of which does not contain any foaming substances, rough granular substances, or sharp protruding structures, and does not cause any structural and performance damage to the substrate film; at the same time, the structure also solves the problem of uniformity in release coating, so that the release force of the polyolefin release film is uniform and stable and the residual joint is low. After long-term storage, the fluctuation of the release force is less than 10%, so that the release film is easier to separate from the coil and less asphalt residue is left after peeling, thereby improving construction efficiency.

[0011] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a polyolefin release film, which includes: a polyolefin polymer roughened surface layer and an organic polymer hardened isolation coating; the organic polymer hardened isolation coating is coated on at least one side of the roughened surface layer; the roughened surface layer includes a polyolefin polymer and a micropowder material embedded therein, at least a portion of the micropowder material protrudes out of the base film of the roughened surface layer, and the micropowder material has no physical state change below 240°C.

[0012] The second aspect of the present invention provides a method for preparing a polyolefin release film, characterized in that the preparation method comprises: laminating other layers except the organic polymer hardened release coating in a mold in one step to prepare a film, coating at least one side of the film with a slurry of the organic polymer hardened release coating and then thermally curing the film to form the polyolefin release film;

[0013] The mold is preferably any one of a circular shape and a flat plate shape;

[0014] The film is preferably prepared in a casting form, a co-extrusion blown film form, or a co-extrusion blown film-extrusion form.

[0015] The coating method is preferably any one of extrusion coating and transfer coating;

[0016] The thermal curing is preferably ultraviolet high-pressure mercury lamp thermal curing; the power of the high-pressure mercury lamp is preferably 10-50 kilowatts, and the thermal curing temperature is preferably 100-140°C;

[0017] The film is preferably subjected to surface roughening treatment and / or corona treatment before coating; the surface roughening is preferably formed by embossing with a roller having a textured surface; the temperature of the embossing treatment is preferably not greater than 130°C, and the pressure is not more than 10kgf; the depth of the roller texture is preferably 0.5-10% of the thickness of the base film of the roughened surface layer (R).

[0018] The third aspect of the present invention provides a method for preparing a roughened surface layer, comprising: blending micropowder particles with a polyolefin polymer, melt extruding, and casting and cooling to form the roughened surface layer;

[0019] The temperature of the melt extrusion is preferably 150 to 250°C;

[0020] Based on the total weight of the micropowder particles and the polyolefin polymer, the added amount of the micropowder particles is preferably 3-20%, and the added amount of the polyolefin polymer is preferably 80-97%.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1) The rough surface adopts a special pattern design, which can ensure the coverage of the release agent at a lower coating weight of the release agent, saving the cost of raw materials.

[0023] 2) It can effectively improve the wrinkles of waterproof membrane during storage and use, and enhance the waterproof performance.

[0024] 3) The release force is stable and the residual joint is low. After long-term storage, the fluctuation of the release force is less than 10%, making it easier to separate the release film from the roll material and less likely to leave asphalt residue after peeling, thereby improving construction efficiency.

[0025] 4) The rough surface does not contain any foaming substances or rough granular substances, but is prepared by molding, which is simple, convenient and practical.

[0026] 5) Compared with the existing embossed release film, the rough surface of the present invention does not contain the sharp protrusion structure in the embossed release film, but is a flat texture, which does not cause any structural and performance damage to the substrate film; at the same time, the structure also better solves the uniformity of the release coating, and the release force is uniform and stable.

[0027] 6) Compared with the existing PE and PP release films, the present invention is a multilayer structure with a rough structure functional layer on the surface. Through the superposition of multiple functional layers, the functional role of each structure is fully exerted, effectively improving the wrinkles of the waterproof roll material during storage and use, and improving the waterproof performance.

[0028] 7) Compared with the existing release film, it can also reduce the migration of small molecules in asphalt and glue and reduce the oxygen exchange between air and the self-adhesive layer, thereby improving the durability of the self-adhesive layer and extending the service life of the waterproof membrane.

[0029] 8) Compared with the existing release film, the peeling force variation range when laminating with the roll material is small, and the film tearing performance is stable. When stored under natural conditions for 50 days, when using white tape as the anti-yellowing test method, the yellowing color difference of the tape is less than 5, while the conventional release film has serious color difference.

[0030] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0032] Figure 1 Schematic diagram of the cross section of the polyolefin release film in Example 1 of the present invention.

[0033] Figure 2 This is a schematic cross-sectional view of the polyolefin release film in Example 2 of the present invention.

[0034] Figure 3 Schematic diagram of the cross section of the polyolefin release film in Example 3 of the present invention.

[0035] Figure 4 Schematic diagram of the embossed pattern on the surface of the polyolefin release film in an embodiment of the present invention.

[0036] R-polyolefin polymer roughened surface layer, Si-organic polymer hardened isolation coating, P-barrier layer, a-polyolefin polymer layer, d-modified adhesive layer DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0038] The present invention provides a polyolefin release film, which comprises: a polyolefin polymer roughened surface layer R and an organic polymer hardened isolation coating Si; the organic polymer hardened isolation coating Si is coated on at least one side of the roughened surface layer R; the roughened surface layer R comprises a polyolefin polymer and a micropowder material embedded therein, at least part of the micropowder material protrudes from the base film of the roughened surface layer R, and the micropowder material has no physical state change below 240°C.

[0039] The no physical state change means that no physical state change such as melting or expansion occurs.

[0040] In the release film of the present invention, the roughened surface layer is formed by organic and / or inorganic micropowders of a certain size. The micropowder material is preferably organic and / or inorganic fillers with non-hollow structures, and most preferably silica micropowders and acrylic resin microspheres. Such micropowders or microspheres are distributed in the roughened layer R, and the structural shape and interlayer position are still intact during high-temperature and high-speed processing, so that the roughened surface layer of the entire release film has a stable roughened structure after molding. Since it is an integrated molding and there is no chemical expansion process during the process, the quality control is convenient and the equipment investment is low.

[0041] The roughened surface layer of the present invention does not contain any foaming substances or coarse granular substances, but is prepared by molding, which is simple, convenient and practical.

[0042] Preferably, the release film further comprises: a barrier layer P and at least one modified adhesive layer.

[0043] The modified adhesive layer is located between the barrier layer P and the roughened surface layer R.

[0044] The organic polymer hardened isolation coating Si is coated on the outer surface of at least one of the roughened surface layers R.

[0045] Preferably, the release film further comprises at least one polyolefin polymer layer.

[0046] The polyolefin polymer layer is in contact with the roughened surface layer R and / or the modified adhesive layer.

[0047] Compared with the existing PE and PP release films, the present invention is a multilayer structure with a rough structure functional layer on the surface. Through the superposition of multiple functional layers, the functional role of each structure is fully exerted, effectively improving the wrinkles of the waterproof roll material during storage and use, and improving the waterproof performance.

[0048] Compared with the existing release film, it can also reduce the migration of small molecules in asphalt and glue and reduce the oxygen exchange between air and the self-adhesive layer, thereby improving the durability of the self-adhesive layer and extending the service life of the waterproof membrane.

[0049] According to the present invention, the polyolefin polymer in the polyolefin polymer roughened surface layer R is selected from at least one of homopolypropylene, copolymer polypropylene, high-density polyethylene, linear polyethylene, linear low-density polyethylene, metallocene polyethylene, and thermoplastic polyolefin elastomer.

[0050] The micropowder material is an organic or inorganic filler with a solid structure, and is preferably selected from at least one of polyacrylic resin microspheres and silicon dioxide micropowder.

[0051] The particle size of the micro powder material is 0.1-280 microns, preferably 0.5-180 microns.

[0052] The size of the base film of the roughened surface layer R of the micro-powder material protruding out is not greater than 4 microns.

[0053] Based on the total mass of the roughened surface layer R, the mass fraction of the micropowder particles is preferably 3-20%, and the mass fraction of the polyolefin polymer is preferably 80-97%.

[0054] The thickness of the roughened surface layer R is 1-10 microns, preferably 3-7 microns.

[0055] Specifically, at least one side of the roughened surface layer R has texture.

[0056] The organic polymer hardened isolation coating Si is coated on the textured side of the roughened surface layer R.

[0057] The texture is preferably an embossing roller texture, and the shape of the texture is preferably any one of a curve, a mesh line, a tree branch, a rectangle, a diamond, and a polygon.

[0058] The depth of the lines is preferably 0.5-10% of the thickness of the base film of the roughened surface layer R.

[0059] The roughened surface layer adopts a special pattern design, which can ensure the coverage of the release agent at a lower coating weight of the release agent, saving raw material costs.

[0060] The non-continuous grain pattern is used to improve the wrinkle problem caused by coil storage, and it is also easier to peel off without leaving any residue after peeling.

[0061] Compared with the existing embossed release film, the roughened surface layer of the present invention does not contain the sharp protrusion structure in the embossed release film, but is a flat texture, which does not cause any structural and performance damage to the substrate film; at the same time, the structure also better solves the uniformity of the release coating, and the release force is uniform and stable.

[0062] According to the present invention, the slurry of the organic polymer hardened isolation coating Si is any one of epoxy-modified organic siloxane compounds, organic acrylate-modified organic siloxane compounds, vinyl organic siloxane compounds, and fluorosilicone polymers.

[0063] The thickness of the organic polymer hardened isolation coating Si is 0.2 to 1.5 microns.

[0064] According to the present invention, the raw material of the barrier layer P is any one of polyamide and ethylene-vinyl alcohol copolymer, and the thickness thereof is 1-10 microns, preferably 2-5 microns.

[0065] The ethylene content of the ethylene-vinyl alcohol copolymer is preferably 21 mol% to 38 mol%.

[0066] The raw material of the modified adhesive layer is at least one of maleic anhydride modified polyethylene and maleic anhydride modified polypropylene.

[0067] The thickness of the modified bonding layer is 1-7 microns, preferably 3-5 microns.

[0068] Specifically, the polyolefin polymer in the polyolefin polymer layer is the same as or different from the polyolefin polymer in the roughened surface layer R, and is selected from at least one of homopolypropylene, copolymer polypropylene, high-density polyethylene, linear polyethylene, linear low-density polyethylene, metallocene polyethylene, and thermoplastic polyolefin elastomer;

[0069] The thickness of the polyolefin polymer layer is 1-10 microns, preferably 3-7 microns.

[0070] The present invention also provides a method for preparing a polyolefin release film, the method comprising: laminating other layers except an organic polymer hardened release coating Si in a mold in one step to prepare a film, coating at least one side of the film with a slurry of the organic polymer hardened release coating Si and then thermally curing the film to form the polyolefin release film;

[0071] The mold is preferably any one of a circular shape and a flat plate shape;

[0072] The film is preferably prepared in a casting form, a co-extrusion blown film form, or a co-extrusion blown film-extrusion form.

[0073] The coating method is preferably any one of extrusion coating and transfer coating;

[0074] The thermal curing is preferably ultraviolet high-pressure mercury lamp thermal curing; the power of the high-pressure mercury lamp is preferably 10-50 kilowatts, and the thermal curing temperature is preferably 100-140°C;

[0075] The film is preferably subjected to surface roughening treatment and / or corona treatment before coating; the surface roughening is preferably formed by embossing with a roller having a textured surface; the temperature of the embossing treatment is preferably not greater than 130°C, and the pressure is not more than 10kgf; the depth of the roller texture is preferably 0.5-10% of the thickness of the base film of the roughened surface layer R.

[0076] The present invention also provides a method for preparing a roughened surface layer, comprising: blending micropowder particles with polyolefin polymers, melt extruding, and casting and cooling to form the roughened surface layer.

[0077] The temperature of the melt extrusion is preferably 150 to 250°C.

[0078] Based on the total weight of the micropowder particles and the polyolefin polymer, the added amount of the micropowder particles is preferably 3-20%, and the added amount of the polyolefin polymer is preferably 80-97%.

[0079] The polyolefin release film has at least one of the following characteristics: the fluctuation of release force is less than 20%, preferably less than 10%; the release film / asphalt roll peeling force range is 5 to 30 g / 25 mm; the 50-day yellowing resistance color difference is less than 15, preferably less than 10.

[0080] The release force fluctuation test is carried out in accordance with GB / T25256, and the method is: after the self-adhesive asphalt with a release film is stored for a period of 50 days, the standard release force of the release film is tested.

[0081] The release force range test is carried out in accordance with GB / T25256. The method is: the self-adhesive asphalt with a release film is stored for a long time and the range of variation of the peeling force during the test process is tested.

[0082] The 50-day non-yellowing test is conducted according to the company's internal testing method, which is: stick a white film tape on the non-silicon side of the release film, and test the color difference of the tape surface before and after long-term storage.

[0083] The present invention is described in more detail below through embodiments, comparative examples and test examples.

[0084] Comparative Example 1

[0085] The polyolefin release film is composed of an embossed convex structure layer and a hardened isolation coating, with a total thickness of 20 microns; the embossed convex structure layer R is 19.5 microns thick and is composed of 100% homopolymer polypropylene, and the hardened isolation coating Si is 0.5 microns thick and is a hard polysiloxane silicone oil layer formed after UV light curing. Homopolymer polypropylene is blown by a 220-250°C screw extruder to form a 19.5 micron thick film, and then passes through an extrusion roller composed of sharp convexities on the surface online to form an embossed convex structure layer; then it is transferred to a coating roller to be evenly coated on the rough surface, and cured and formed by a UV light curing device.

[0086] Example 1

[0087] This example is used to illustrate the preparation method of the polyolefin release film of the present invention.

[0088] The polyolefin release film is composed of a polyolefin polymer roughened surface layer R and an organic polymer hardened isolation coating Si, with a total thickness of 20 μm; the polyolefin polymer roughened surface layer R is 19.5 microns thick and is composed of 100% homopolymer polypropylene and 15% by mass of silica powder; the organic polymer hardened isolation coating Si is 0.5 microns thick and is a hard polysiloxane silicone oil layer formed after UV light curing. The silica powder is blended with homopolymer polypropylene and blown by a 220-250°C screw extruder to form a 19.5 micron thick film, and then passed through an extrusion roller with a surface prefabricated with points and curves to form a polyolefin polymer roughened surface layer R; then it is transferred to a coating roller to evenly coat the slurry of the organic polymer hardened isolation coating Si on the rough surface, and cured and formed by UV light curing equipment.

[0089] Example 2

[0090] This example is used to illustrate the preparation method of the polyolefin release film of the present invention.

[0091] The polyolefin release film has a thickness of 40 microns and is composed of a polyolefin polymer roughened surface layer R, a polyolefin polymer layer a, a modified adhesive layer d, a barrier layer P, and an organic polymer hardened isolation coating Si. The polyolefin polymer roughened surface layer R has a thickness of 3.9 microns and is composed of 55% high-density polyethylene (HDPE), 40% linear low-density polyethylene (LLDPE), 5% homopolymer polypropylene (MPP), and 10% silica powder by mass; the polyolefin polymer layer a has a thickness of 5 microns and is composed of 55% linear low-density polyethylene (LLDPE) and 45% high-density polyethylene (HDPE); the modified adhesive layer d has a thickness of 4 microns and is composed of 100% maleic anhydride modified polyethylene; the barrier layer P has a thickness of 4 microns and is composed of 100% nylon 6. Silica powder is blended with high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and homopolymer polypropylene (MPP) and blown into a polyolefin polymer roughened surface layer R with a thickness of 3.9 microns through a screw extruder at 220-250°C; the polyolefin polymer roughened surface layer R is sequentially stacked with other layers and blown into a co-extrusion film; then, after passing through an extrusion roller with a surface prefabricated with points and curves, a slurry of an organic polymer hardened isolation coating Si is coated, and finally heat-cured to form; wherein the thickness of the organic polymer hardened isolation coating Si is 0.2 microns.

[0092] Example 3

[0093] This example is used to illustrate the preparation method of the polyolefin release film of the present invention.

[0094] The polyolefin release film has a thickness of 20 microns and is composed of a polyolefin polymer roughened surface layer R, a modified adhesive layer d, a barrier layer P, and an organic polymer hardened isolation coating Si. The polyolefin polymer roughened surface layer R has a thickness of 3.8 microns and is composed of 40% homopolymer polypropylene, 60% copolymer polypropylene, and 15% by weight of polyacrylic resin microspheres; the modified adhesive layer has a thickness of 4 microns and is composed of 100% maleic anhydride modified polypropylene; the barrier layer P has a thickness of 4 microns and is composed of 100% EVOH. The polyacrylic resin microspheres are blended with homo-polypropylene and copolymer polypropylene and blown through a screw extruder at 220-250°C to form a 3.8 micron thick polyolefin polymer roughened surface layer R; the polyolefin polymer roughened surface layer R is sequentially stacked with other layers and co-extruded and cast; then, after passing through an extrusion roller with a surface prefabricated with points and curves, a slurry of an organic polymer hardened isolation coating Si is coated, and finally UV curing is performed; wherein the thickness of the organic polymer hardened isolation coating Si is 0.4 micron.

[0095] Test Example 1

[0096] The release films prepared in the comparative example and Examples 1-3 were applied to the self-adhesive asphalt coil to test the silicone oil coating weight. The test method was: Oxford Lab-X3500 silicone coating tester was used for testing. The test results are shown in Table 1.

[0097] Test Example 2

[0098] The release films prepared in the comparative example and Examples 1-3 were applied to the self-adhesive asphalt roll to test the release force. The test method was: using a 25 mm wide Tesa 7475 tape for testing. The test results are shown in Table 1.

[0099] Test Example 3

[0100] The release films prepared in the comparative example and Examples 1-3 were applied to the self-adhesive asphalt coil performance for release film / asphalt peeling force test. The test method was as follows: a 25 mm release film was attached to the surface of the asphalt self-adhesive layer, and a pressure roller was used to move back and forth evenly for 3 times, and the film was left for 24 hours. After the debugging was completed, the film was tested at a speed of 300 mm / min. The test results are shown in Table 1.

[0101] Test Example 4

[0102] The release films prepared in the comparative example and Examples 1-3 were applied to the self-adhesive asphalt coil performance to carry out the asphalt self-adhesive layer / aluminum plate peeling force test. The test was carried out in accordance with GB / T23441. The method was as follows: a 50 mm wide asphalt self-adhesive layer was attached to the aluminum plate, and rolled back and forth with a roller for 3 times, left to stand for 24 hours, and then tested at a speed of 100 mm / min. The test results are shown in Table 1.

[0103] Test Example 5

[0104] The release films prepared in the comparative example and Examples 1-3 were applied to the self-adhesive asphalt coil performance to test the asphalt self-adhesive layer / aluminum plate bonding peeling force retention rate after thermal aging. The test was carried out in accordance with GB / T23441. The method is: the self-adhesive asphalt with the release film is placed in a 70°C oven for heat treatment for 7 days and then tested. The test results are shown in Table 1.

[0105] Test Example 6

[0106] The release films prepared in the comparative example and Examples 1-3 were used to test the release force fluctuation of the self-adhesive asphalt roll. The test was carried out in accordance with GB / T25256. The method was as follows: after the self-adhesive asphalt with the release film was stored for a period of 50 days, the standard release force of the release film was tested. The test results are shown in Table 1.

[0107] Test Example 7

[0108] The release films prepared in the comparative example and Examples 1-3 were used to test the release force range of the self-adhesive asphalt roll. The test was carried out in accordance with GB / T25256. The method was as follows: the self-adhesive asphalt with the release film was stored for a long time and the range of variation of the peeling force during the test was tested. The test results are shown in Table 1.

[0109] Test Case 8

[0110] The release films prepared in the comparative example and Examples 1-3 were applied to the self-adhesive asphalt roll material for a 50-day non-yellowing performance test. The test was conducted according to the company's internal test method, which is: a white film tape was attached to the non-silicon surface of the release film, and the color difference of the tape surface before and after long-term storage was tested. The test results are shown in Table 1.

[0111] Table 1

[0112]

[0113] From the comparative data in Table 1, it can be seen that the various properties of Example 3 are the most excellent. In terms of silicone oil coating weight, Example 3 is 0.4 g / m 2, while the release agent coating weights of Example 1, Example 2 and Comparative Example 1 are also very low, which indicates that the rough surface adopts a special pattern design, and the coverage of the release agent can be guaranteed at a lower release agent coating weight. In terms of the release film / asphalt peeling force, Examples 1-3 are all relatively low, indicating that the roughened surface layer R embedded with micropowder material has excellent peeling force. In terms of the appearance of asphalt coiled materials, Examples 1-3 are all wrinkle-free, indicating that the superposition of multiple functional layers in the release film improves its anti-wrinkle performance. In terms of the asphalt self-adhesive layer / aluminum plate bonding peeling force retention rate after thermal aging, Examples 1-3 perform excellently, indicating that the roughened surface layer R embedded with micropowder material is not easy to be thermally bonded with the asphalt self-adhesive layer. In the test of the fluctuation of the release force, the release force of Examples 1-3 fluctuates very little over time, indicating that the performance of the release film coated with silicon after the rough structure is stable. In terms of the release force range, the variation range of Examples 1-3 is very small during the long-term storage of the asphalt coil, indicating that the release film coated with silicon using a rough structure and UV curing method has stable performance and excellent peeling force with the asphalt coil. In the 50-day yellowing resistance test, the color difference changes of Examples 1-3 are significantly better than those of the comparative example, indicating that the structural design of the roughened layer has improved its yellowing resistance to a certain extent, and the multiple functional layer structure has effectively improved the yellowing resistance.

[0114] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a polyolefin release film, It is characterized in that The release film comprises: a polyolefin polymer roughened surface layer (R) and an organic polymer hardened isolation coating layer (Si); The organic polymer hardened isolation coating (Si) is coated on at least one side of the roughened surface layer (R); The roughened surface layer (R) comprises a polyolefin polymer and a micropowder material embedded therein, at least a portion of the micropowder material protrudes from the base film of the roughened surface layer (R), and the micropowder material has no physical state change below 240° C.; The release film further comprises: a barrier layer (P) and at least one modified adhesive layer; The modified adhesive layer is located between the barrier layer (P) and the roughened surface layer (R); The organic polymer hardened barrier coating (Si) is coated on the outer surface of at least one of the roughened surface layers (R); The size of the base film of the micro-powder material protruding from the roughened surface layer (R) is not greater than 4 microns; The roughened surface layer (R) has texture on at least one side; The organic polymer hardened isolation coating (Si) is coated on the textured side of the roughened surface layer (R); The depth of the lines is 0.5-10% of the thickness of the base film of the roughened surface layer (R); The preparation method comprises: laminating the other layers except the organic polymer hardened isolation coating (Si) in a mold in one step to prepare a film, coating at least one side of the film with a slurry of the organic polymer hardened isolation coating (Si) and then thermally curing the slurry to form the polyolefin release film; The surface roughening is formed by embossing with a roller having a texture on the surface; The depth of the roller texture is 0.5-10% of the thickness of the base film of the roughened surface layer (R).

2. The method for preparing a polyolefin release film according to claim 1, It is characterized in that The release film further comprises at least one polyolefin polymer layer; the polyolefin polymer layer is in contact with the roughened surface layer (R).

3. The method for preparing a polyolefin release film according to claim 1, It is characterized in that The release film further comprises at least one polyolefin polymer layer; the polyolefin polymer layer is in contact with the roughened surface layer (R) and / or the modified adhesive layer.

4. A method for preparing a polyolefin release film according to any one of claims 1 to 3, It is characterized in that The polyolefin polymer in the polyolefin polymer roughened surface layer (R) is selected from at least one of homopolypropylene, copolymer polypropylene, high-density polyethylene, linear polyethylene, linear low-density polyethylene, metallocene polyethylene, and thermoplastic polyolefin elastomer; The micro powder material is an organic or inorganic filler with a solid structure; The particle size of the micro powder material is 0.1 to 280 microns; The thickness of the roughened surface layer (R) is 1-22 microns.

5. The method for preparing a polyolefin release film according to claim 4, It is characterized in that The micro powder material is selected from at least one of polyacrylic resin microspheres and silicon dioxide micro powder; The particle size of the micro powder material is 0.5-180 microns; Based on the total mass of the roughened surface layer (R), the mass fraction of the micropowder material is 3-20%, and the mass fraction of the polyolefin polymer is 80-97%; The thickness of the roughened surface layer (R) is 3-20 microns.

6. A method for preparing a polyolefin release film according to any one of claims 1 to 3, It is characterized in that The slurry of the organic polymer hardened isolation coating (Si) is any one of epoxy-modified organic siloxane compounds, organic acrylate-modified organic siloxane compounds, vinyl organic siloxane compounds, and fluorosilicone polymers; The thickness of the organic polymer hardened isolation coating (Si) is 0.2-1.5 microns.

7. The method for preparing a polyolefin release film according to claim 1, It is characterized in that The texture is an embossing roller texture, and the shape of the texture is any one of a curve, a mesh line, a tree branch, a rectangle, a diamond, and a polygon.

8. The method for preparing a polyolefin release film according to any one of claims 1 or 3, It is characterized in that The barrier layer (P) is made of any one of polyamide and ethylene-vinyl alcohol copolymer, and has a thickness of 1-10 μm; The raw material of the modified adhesive layer is at least one of maleic anhydride modified polyethylene and maleic anhydride modified polypropylene; The thickness of the modified adhesive layer is 1-7 microns.

9. The method for preparing a polyolefin release film according to claim 8, It is characterized in that The thickness of the barrier layer (P) is 2-5 μm; The ethylene content of the ethylene-vinyl alcohol copolymer is 21 mol% to 38 mol%; The thickness of the modified adhesive layer is 3-5 microns.

10. The method for preparing a polyolefin release film according to any one of claims 2 to 3, It is characterized in that The polyolefin polymer in the polyolefin polymer layer is the same as or different from the polyolefin polymer in the roughened surface layer (R), and is selected from at least one of homopolypropylene, copolymer polypropylene, high-density polyethylene, linear polyethylene, linear low-density polyethylene, metallocene polyethylene, and thermoplastic polyolefin elastomer; The thickness of the polyolefin polymer layer is 1-10 microns.

11. The method for preparing a polyolefin release film according to claim 10, It is characterized in that The thickness of the polyolefin polymer layer is 3-7 microns.

12. The method for preparing a polyolefin release film according to claim 1, It is characterized in that The mold is any one of a circular shape and a flat plate shape; The film is prepared in any one of a casting method, a co-extrusion blown film method, and a co-extrusion blown film-extrusion method; The coating method is any one of extrusion coating and transfer coating; The thermal curing is ultraviolet high pressure mercury lamp thermal curing; The film is subjected to surface roughening treatment and / or corona treatment before coating; The roughened surface layer (R) is prepared by the following method: blending micropowder particles with polyolefin polymers, melt extruding, and casting and cooling to form the roughened surface layer (R); The temperature of the embossing treatment is not more than 130°C, and the pressure is not more than 10kgf; The power of the high-pressure mercury lamp is 10-50 kilowatts, and the thermal curing temperature is 100-140°C; The temperature of the melt extrusion is 150-250°C; Based on the total weight of the micropowder particles and the polyolefin polymer, the added amount of the micropowder particles is 3-20%, and the added amount of the polyolefin polymer is 80-97%.

13. The method for preparing the polyolefin release film according to claim 1, It is characterized in that The polyolefin release film has at least one of the following characteristics: The fluctuation of release force is less than 20%; The peeling force range of release film / asphalt membrane is 5~30g / 25mm; The yellowing resistance color difference is less than 15 after 50 days.

14. The method for preparing a polyolefin release film according to claim 13, It is characterized in that The fluctuation of release force is less than 10%; The color difference of yellowing resistance is less than 10 after 50 days.

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