Polyolefin flame-retardant weather-resistant adhesive film, preparation method thereof and film-coated board

Abstract

The present application relates to the technical field of metal laminated board, and particularly relates to a polyolefin flame-retardant weather-resistant adhesive film, a preparation method thereof and a laminated board. The polyolefin flame-retardant weather-resistant adhesive film comprises a first protective layer, a second protective layer, a flame-retardant core layer and an adhesive layer which are sequentially stacked; the first protective layer comprises TPO, a first polyolefin elastomer, titanium white, an antioxidant, a light stabilizer and an acid absorbent; the second protective layer comprises a second polyolefin elastomer, magnesium hydroxide, maleic anhydride grafted polyethylene and an antioxidant; the flame-retardant core layer comprises polyethylene resin, magnesium hydroxide, maleic anhydride grafted polyethylene and an antioxidant; and the adhesive layer comprises polyolefin adhesive resin grafted with maleic anhydride. The polyolefin flame-retardant weather-resistant adhesive film has good flame retardancy and excellent weather resistance, and can maintain a long-lasting interfacial adhesive strength with a metal substrate, so that the service life of the metal material is prolonged and the environmental adaptability is improved when the polyolefin flame-retardant weather-resistant adhesive film is applied to the laminated board.

Description

Technical Field

[0001] This invention relates to the field of metal-coated panel technology, and in particular to a polyolefin flame-retardant and weather-resistant adhesive film, its preparation method, and the coated panel thereof. Background Technology

[0002] Polymer coating, as a new type of metal external corrosion protection technology, has outstanding advantages such as good coating uniformity, excellent corrosion resistance, strong weather resistance and high environmental protection. It is gradually replacing traditional oil-based paints and powder coatings and is widely used in building decoration materials, home appliance shells, roof curtain walls and other fields.

[0003] Polyolefin laminated panels are one of the mainstream laminated metal sheets currently available. While the polyolefin film used in these panels possesses anti-corrosion and weather-resistant properties, it lacks flame retardancy in its unmodified form, limiting its widespread adoption and application. To achieve flame retardancy in polyolefins, large amounts of flame retardants such as magnesium hydroxide are typically added. However, magnesium hydroxide exhibits poor dispersion in the polyolefin matrix, which weakens the mechanical properties, weather resistance, and anti-corrosion performance of the film material. In particular, it is easily corroded by highly penetrating organic gases such as hydrofluoric acid, severely impacting the protective effect and service life of polyolefin laminated panels when used outdoors.

[0004] Chinese patent application CN116836477A discloses a TPO flame-retardant composition that utilizes alkyl phosphates to reduce surface polarity, thereby improving the dispersibility of fillers such as magnesium hydroxide and titanium dioxide in TPO and balancing the flame-retardant properties and weather resistance of the material to some extent. However, existing laminated panels still contain a large amount of flame retardants such as magnesium hydroxide in their surface materials. Although the dispersibility is improved, the introduction of a large amount of flame retardants still has a significant impact on the mechanical properties and weather resistance of the panels, making them prone to powdering and cracking during long-term outdoor use. In addition, existing technologies require additional adhesives to bond the surface layer to the metal sheet, which is not only unfavorable for continuous production, but also often makes it difficult to achieve both reliable adhesion and flame retardancy.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a polyolefin flame-retardant and weather-resistant adhesive film, its preparation method, and a coated board. The polyolefin flame-retardant and weather-resistant adhesive film of this invention has both good flame retardancy and excellent weather resistance, and can maintain a long-lasting interfacial adhesion strength with the metal substrate. Applying it to a coated board helps to extend the service life of metal materials and improve their environmental adaptability.

[0007] To achieve the above-mentioned objectives of the present invention, a first aspect of the present invention provides a polyolefin flame-retardant and weather-resistant adhesive film, comprising a first protective layer, a second protective layer, a flame-retardant core layer and an adhesive layer stacked sequentially. The first protective layer comprises the following components by weight: 55-80 parts of TPO, 15-35 parts of the first polyolefin elastomer, 5-15 parts of titanium dioxide, 0.1-3 parts of antioxidant, 0.1-3 parts of light stabilizer, and 0.1-3 parts of acid absorber; The second protective layer comprises the following components by weight: 40-75 parts of a second polyolefin elastomer, 20-35 parts of magnesium hydroxide, 2-5 parts of maleic anhydride-grafted polyethylene, and 0.1-3 parts of an antioxidant. The flame-retardant core layer comprises the following components by weight: 30-55 parts polyethylene resin, 40-60 parts magnesium hydroxide, 5-10 parts maleic anhydride-grafted polyethylene, and 0.1-3 parts antioxidant. The adhesive layer comprises a polyolefin adhesive resin grafted with maleic anhydride.

[0008] In a specific embodiment of the present invention, the melt index of the TPO under the conditions of 230℃ / 2.16kg is 0.5~4g / 10min, and the melting point is 140~165℃.

[0009] In a specific embodiment of the present invention, the melt index of the first polyolefin elastomer under the condition of 230℃ / 2.16kg is 7~10g / 10min, and the Vicat softening point is 40~65℃.

[0010] In a specific embodiment of the present invention, the mass ratio of TPO to the first polyolefin elastomer in the first protective layer is (2.5~4):1.

[0011] In a specific embodiment of the present invention, the melt index of the second polyolefin elastomer under the conditions of 230°C / 2.16kg is 2~5g / 10min, and the Vicat softening point is 60~95°C.

[0012] In a specific embodiment of the present invention, the grafting rate of the maleic anhydride-grafted polyethylene is 0.5% to 1.5%.

[0013] In a specific embodiment of the present invention, the melt index of the polyolefin adhesive resin grafted with maleic anhydride under the conditions of 230°C / 2.16kg is 2~5g / 10min, and the Vicat softening point is 70~85°C.

[0014] In a specific embodiment of the present invention, the thickness ratio of the first protective layer, the second protective layer, the flame-retardant core layer and the adhesive layer is (1~3) : (1~3) : (4~8) : 1.

[0015] In a specific embodiment of the present invention, the thickness of the polyolefin flame-retardant and weather-resistant adhesive film is 0.1~0.3mm.

[0016] In a specific embodiment of the present invention, the thickness of the first protective layer is 0.02~0.05mm; the thickness of the second protective layer is 0.02~0.05mm; and the thickness of the flame-retardant core layer is 0.08~0.12mm.

[0017] The second aspect of the present invention provides a method for preparing the polyolefin flame-retardant and weather-resistant adhesive film provided in the first aspect of the present invention, comprising the following steps: performing multilayer co-extrusion casting or blown film casting of the first protective layer raw material, the second protective layer raw material, the flame-retardant core layer raw material and the adhesive layer raw material to obtain the polyolefin flame-retardant and weather-resistant adhesive film.

[0018] A third aspect of the present invention provides a coated panel, comprising a metal substrate and a polyolefin flame-retardant and weather-resistant adhesive film disposed on at least one surface of the metal substrate; the polyolefin flame-retardant and weather-resistant adhesive film is the polyolefin flame-retardant and weather-resistant adhesive film provided in the first aspect of the present invention.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The polyolefin flame retardant and weather resistant adhesive film of the present invention has a multi-layer structure consisting of a first protective layer, a second protective layer, a flame retardant core layer and an adhesive layer, and the composition of each layer is designed to make it have both good flame retardancy and excellent weather resistance, while maintaining a long-lasting interfacial bonding strength with the metal substrate.

[0020] (2) The film-coated board of the present invention is formed by hot pressing a polyolefin flame-retardant and weather-resistant adhesive film and a metal substrate in one step, without the need for additional adhesive processes, and without VOC emissions during the process. It also has the advantages of high production efficiency and good product quality stability. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0022] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] The first aspect of the present invention provides a polyolefin flame-retardant and weather-resistant adhesive film, comprising a first protective layer, a second protective layer, a flame-retardant core layer and an adhesive layer stacked sequentially; The first protective layer comprises the following components by weight: 55-80 parts of TPO, 15-35 parts of the first polyolefin elastomer, 5-15 parts of titanium dioxide, 0.1-3 parts of antioxidant, 0.1-3 parts of light stabilizer, and 0.1-3 parts of acid absorber; The second protective layer comprises the following components by weight: 40-75 parts of a second polyolefin elastomer, 20-35 parts of magnesium hydroxide, 2-5 parts of maleic anhydride-grafted polyethylene, and 0.1-3 parts of an antioxidant. The flame-retardant core layer comprises the following components by weight: 30-55 parts polyethylene resin, 40-60 parts magnesium hydroxide, 5-10 parts maleic anhydride-grafted polyethylene, and 0.1-3 parts antioxidant. The adhesive layer comprises a polyolefin adhesive resin grafted with maleic anhydride.

[0024] The polyolefin flame-retardant and weather-resistant adhesive film of the present invention has a multi-layer structure consisting of a first protective layer, a second protective layer, a flame-retardant core layer, and an adhesive layer. The composition of each layer is designed. The first protective layer gives the adhesive film excellent weather resistance, the flame-retardant core layer achieves good flame retardancy, the second protective layer provides a good transition between the first protective layer and the flame-retardant core layer, and the adhesive layer can be firmly bonded to the metal substrate through high-temperature hot-pressing. At the same time, the layers have good compatibility, so that the polyolefin flame-retardant and weather-resistant adhesive film has both good flame retardancy and excellent weather resistance, and can maintain a long-lasting interfacial bonding strength with the metal substrate.

[0025] In a specific embodiment of the present invention, the first protective layer comprises the following components by weight: 55-80 parts of TPO, 15-35 parts of the first polyolefin elastomer, 5-15 parts of titanium dioxide, 0.1-3 parts of antioxidant, 0.1-3 parts of light stabilizer and 0.1-3 parts of acid absorber. In different embodiments, the amount of TPO, by weight, can be 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, or any combination thereof; the amount of the first polyolefin elastomer can be 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, or any combination thereof; the amount of titanium dioxide can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, or any combination thereof; the amount of antioxidant can be 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, or any combination thereof; the amount of light stabilizer can be 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, or any combination thereof; and the amount of acid scavenger can be 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, or any combination thereof.

[0026] TPO, as the base resin of the first protective layer, imparts a certain degree of rigidity and strength to the layer. The first polyolefin elastomer exhibits relatively good compatibility with substances such as titanium dioxide. Through the compounding of the two, it is possible to ensure that the layer maintains good mechanical integrity, processing fluidity, and interlayer bonding stability even with a high titanium dioxide content to improve its aging resistance and UV blocking performance. This avoids problems such as increased brittleness, surface defects, or peeling from adjacent layers caused by high filler content, thereby achieving long-term protection for the flame-retardant core layer and adhesive layer.

[0027] In a specific embodiment of the present invention, the second protective layer comprises the following components by weight: 40-75 parts of a second polyolefin elastomer, 20-35 parts of magnesium hydroxide, 2-5 parts of maleic anhydride-grafted polyethylene, and 0.1-3 parts of an antioxidant. In different embodiments, the amount of the second polyolefin elastomer by weight can be 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, or any combination thereof; the amount of magnesium hydroxide can be 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, or any combination thereof; the amount of maleic anhydride-grafted polyethylene can be 2 parts, 3 parts, 4 parts, 5 parts, or any combination thereof; and the amount of the antioxidant can be 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, or any combination thereof.

[0028] The selection and dosage of components in the second protective layer serve two purposes: firstly, to improve the flame-retardant properties of the polyolefin flame-retardant and weather-resistant film; and secondly, to connect the first protective layer and the flame-retardant core layer, ensuring a smooth transition and preventing delamination and poor processability due to poor compatibility. Specifically, the second polyolefin elastomer, as the base resin of the second protective layer, needs to ensure the dispersion of magnesium hydroxide and its connection to adjacent layers. If the dosage of the second polyolefin elastomer is too low, it will hinder the dispersion of magnesium hydroxide and easily lead to insufficient interlayer adhesion; if the dosage is too high, the relative content of magnesium hydroxide will decrease, which is detrimental to improving the flame-retardant properties.

[0029] In a specific embodiment of the present invention, the flame-retardant core layer comprises the following components by weight: 30-55 parts of polyethylene resin, 40-60 parts of magnesium hydroxide, 5-10 parts of maleic anhydride-grafted polyethylene, and 0.1-3 parts of antioxidant. In different embodiments, the amount of polyethylene resin by weight can be 30 parts, 35 parts, 40 parts, 45 parts, 55 parts, or any combination thereof; the amount of magnesium hydroxide can be 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, or any combination thereof; the amount of maleic anhydride-grafted polyethylene can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, or any combination thereof; and the amount of antioxidant can be 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, or any combination thereof. Adding a large amount of magnesium hydroxide to the flame-retardant core layer, along with the use of polyethylene resin and maleic anhydride-grafted polyethylene, can improve the uniformity of magnesium hydroxide dispersion in this layer, thus ensuring flame retardant performance, processability, and interlayer compatibility.

[0030] The adhesive layer uses a polyolefin adhesive resin grafted with maleic anhydride, which can form a stable bond with metal through surface chemical coordination bonds. Moreover, there are no VOC emissions during use, making it more reliable and environmentally friendly than traditional adhesives.

[0031] Furthermore, the polyolefin flame-retardant and weather-resistant film of the present invention, through the above-mentioned layer composition design, not only has good compatibility between the layers, but also has good processing performance. It can be prepared by multi-layer co-extrusion blown film or casting, and can be composited with metal by hot pressing without additional adhesive processes. The resulting polyolefin coated board can be widely used in building decoration and other fields.

[0032] In a specific embodiment of the present invention, the melt index of the TPO under the condition of 230℃ / 2.16kg is 0.5~4g / 10min, specifically it can be a range of 0.5g / 10min, 1g / 10min, 2g / 10min, 3g / 10min, 4g / 10min or any two of them. The melt index within this range can ensure that the first protective layer has suitable melt strength and processing fluidity. The melting point is 140~165℃, specifically it can be a range of 140℃, 145℃, 150℃, 155℃, 160℃, 165℃ or any two of them. The melting point within this range allows the first protective layer to have suitable processing window and heat resistance.

[0033] In specific embodiments of the present invention, the TPO includes, but is not limited to, at least one of LyondellBasell Hifax CA1147A and LyondellBasell Adflex Q 300F.

[0034] In a specific embodiment of the present invention, the melt index of the first polyolefin elastomer under the condition of 230℃ / 2.16kg is 7~10g / 10min, specifically it can be a range of 7g / 10min, 7.5g / 10min, 8g / 10min, 9g / 10min, 10g / 10min or any two of them. The first polyolefin elastomer has relatively high fluidity and can be fully mixed and dispersed with TPO, titanium dioxide, etc., to improve the processing performance of the first protective layer. The Vicat softening point is 40~65℃, specifically it can be a range of 40℃, 45℃, 50℃, 55℃, 60℃, 65℃ or any two of them, which is more conducive to the balance between the mechanical properties and processing performance of the first protective layer.

[0035] In a specific embodiment of the present invention, the first polyolefin elastomer includes, but is not limited to, at least one of Exxon Vistamaxx 3000, Exxon Vistamaxx 6000, and Dow Versify 3200.

[0036] In a specific embodiment of the present invention, the mass ratio of TPO to the first polyolefin elastomer in the first protective layer is (2.5~4):1, specifically within the range of 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, or any combination thereof. Controlling the ratio of TPO to the first polyolefin elastomer in the first protective layer within the above range is more conducive to balancing the mechanical properties, weather resistance, and processing performance of the first protective layer. If the ratio is too high (too much TPO), it is not conducive to the dispersion of additives such as titanium dioxide, leading to a decrease in mechanical properties and difficulties in film formation; if the ratio is too low (too little TPO), the weather resistance is insufficient.

[0037] In a specific embodiment of the present invention, the melt index of the second polyolefin elastomer at 230°C / 2.16kg is 2~5g / 10min, specifically within the range of 2g / 10min, 2.5g / 10min, 3g / 10min, 3.5g / 10min, 4g / 10min, 4.5g / 10min, 5g / 10min, or any combination thereof; the Vicat softening point is 60~95°C, specifically within the range of 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or any combination thereof. The melt index and Vicat softening point of the second polyolefin elastomer satisfying the above conditions not only ensure the uniform dispersion of magnesium hydroxide within the layer but also guarantee the compatibility of the interlayer structure.

[0038] In a specific embodiment of the present invention, the second polyolefin elastomer includes, but is not limited to, at least one of Dow Versify 2000, Dow Versify 2200, and Exxon Vistamaxx 3020FL.

[0039] In a specific embodiment of the present invention, the grafting rate of the maleic anhydride-grafted polyethylene is 0.5% to 1.5%, specifically 0.5%, 0.8%, 1%, 1.2%, 1.5%, or any two of these ranges, to improve the uniformity of the dispersion of fillers such as magnesium hydroxide in the matrix.

[0040] In a specific embodiment of the present invention, the polyethylene resin includes, but is not limited to, at least one of Guangzhou Petrochemical 7042, CNOOC Shell 2420H, and Yangzi Petrochemical 5000S.

[0041] In a specific embodiment of the present invention, the melt index of the polyolefin adhesive resin grafted with maleic anhydride at 230°C / 2.16kg is 2~5g / 10min, specifically 2g / 10min, 3g / 10min, 4g / 10min, 5g / 10min or any combination thereof; the Vicat softening point is 70~85°C, specifically 70°C, 75°C, 80°C, 85°C or any combination thereof.

[0042] In a specific embodiment of the present invention, the polyolefin adhesive resin grafted with maleic anhydride includes, but is not limited to, at least one of Guangzhou Lushan TP101 and VB790.

[0043] In a specific embodiment of the present invention, the titanium dioxide is rutile titanium dioxide. Further, the average particle size of the titanium dioxide is 0.2~0.5 μm, specifically within the range of 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, or any combination thereof.

[0044] In a specific embodiment of the present invention, the acid absorbent includes at least one of aluminum hydroxide, calcium stearate, and magnesium hydroxide. Further, the average particle size of the acid absorbent is 10-15 μm, specifically within the range of 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any combination thereof.

[0045] In a specific embodiment of the present invention, the antioxidants in the first protective layer, the second protective layer and the flame-retardant core layer may be independently selected from at least one of antioxidant 1010, antioxidant 1076, antioxidant 1024, antioxidant 168, antioxidant 264 and antioxidant 245.

[0046] In a specific embodiment of the present invention, the light stabilizer in the first protective layer may be selected from at least one of hindered amine light stabilizers, benzophenone light stabilizers, and benzotriazole light stabilizers.

[0047] In a specific embodiment of the present invention, the average particle size of magnesium hydroxide in the second protective layer and the flame-retardant core layer is 1.5~2.5μm, specifically it can be a range of 1.5μm, 1.8μm, 2μm, 2.2μm, 2.5μm or any combination thereof.

[0048] In a specific embodiment of the present invention, the thickness ratio of the first protective layer, the second protective layer, the flame-retardant core layer, and the adhesive layer is (1~3):(1~3):(4~8):1. Specifically, the thickness ratio of the first protective layer to the adhesive layer can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or any combination thereof; the thickness ratio of the second protective layer to the adhesive layer can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or any combination thereof; the thickness ratio of the flame-retardant core layer to the adhesive layer can be 4:1, 5:1, 6:1, 7:1, 8:1, or any combination thereof. By adjusting the thickness of each layer to meet the above conditions, a good balance can be achieved between weather resistance, flame retardancy, and adhesive strength.

[0049] In a specific embodiment of the present invention, the thickness of the polyolefin flame-retardant and weather-resistant adhesive film is 0.1~0.3mm, specifically it can be a range of 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm or any two of them.

[0050] In a specific embodiment of the present invention, the thickness of the first protective layer is 0.02~0.05mm; the thickness of the second protective layer is 0.02~0.05mm; and the thickness of the flame-retardant core layer is 0.08~0.12mm.

[0051] In a specific embodiment of the present invention, the polyolefin flame-retardant and weather-resistant adhesive film is integrally formed from the raw materials of the first protective layer, the second protective layer, the flame-retardant core layer and the adhesive layer through a multi-layer co-extrusion process.

[0052] The second aspect of the present invention provides a method for preparing the polyolefin flame-retardant and weather-resistant adhesive film provided in the first aspect of the present invention, comprising the following steps: performing multilayer co-extrusion casting or blown film casting of the first protective layer raw material, the second protective layer raw material, the flame-retardant core layer raw material and the adhesive layer raw material to obtain the polyolefin flame-retardant and weather-resistant adhesive film.

[0053] In a specific embodiment of the present invention, the preparation of the first protective layer material, the second protective layer material, and the flame-retardant core layer material includes: mixing them according to the composition ratio of the first protective layer, the second protective layer, and the flame-retardant core layer, respectively, and then melt-extruding and granulating them to obtain the first protective layer material, the second protective layer material, and the flame-retardant core layer material.

[0054] In a specific embodiment of the present invention, the preparation of the first protective layer raw material, the second protective layer raw material, and the flame-retardant core layer raw material is carried out by melt extrusion granulation using a twin-screw extruder. Further, the melt extrusion temperature is 190~230℃, the screw speed is 300~350rpm, the feed rate is 5~7Hz, and the length-to-diameter ratio of the twin screw is (36~44):1. In a specific embodiment of the present invention, a multi-layer co-extrusion casting machine or a multi-layer co-extrusion blown film machine is used for multi-layer co-extrusion. Further, the multi-layer co-extrusion processing temperature is 150–210°C.

[0055] A third aspect of the present invention provides a coated panel, comprising a metal substrate and a polyolefin flame-retardant and weather-resistant adhesive film disposed on at least one surface of the metal substrate; the polyolefin flame-retardant and weather-resistant adhesive film is the polyolefin flame-retardant and weather-resistant adhesive film provided in the first aspect of the present invention.

[0056] In a specific embodiment of the present invention, the coated plate includes a metal substrate and a polyolefin flame-retardant and weather-resistant adhesive film disposed on both sides of the metal substrate; the adhesive layer of the polyolefin flame-retardant and weather-resistant adhesive film is attached to the metal substrate.

[0057] In a specific embodiment of the present invention, the coated board is prepared by hot-pressing the metal substrate with a polyolefin flame-retardant and weather-resistant adhesive film; the hot-pressing temperature is 160~200℃, specifically a range of 160℃, 170℃, 180℃, 190℃, 200℃, or any combination thereof; the hot-pressing pressure is 0.3~0.6MPa, specifically a range of 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, or any combination thereof. In actual operation, hot-pressing can be performed using a continuous roller pressing device.

[0058] Example 1 This embodiment provides a polyolefin flame-retardant and weather-resistant adhesive film, comprising a first protective layer, a second protective layer, a flame-retardant core layer, and an adhesive layer stacked sequentially from top to bottom, with thicknesses of 0.04 mm, 0.04 mm, 0.1 mm, and 0.02 mm respectively.

[0059] The first protective layer comprises the following components by weight: 68 parts of LyondellBasell Hifax CA 1147A, 20 parts of Dow Versify 3200, 10 parts of titanium dioxide (average particle size 0.4 μm), 0.5 parts of calcium stearate (average particle size 10 μm), 0.6 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 0.4 parts of light stabilizer UV-622, and 0.3 parts of light stabilizer UV-326.

[0060] The second protective layer comprises the following components by weight: 70.7 parts of Dow VERSIFY 2200, 25 parts of magnesium hydroxide (average particle size of 2 μm), 4 parts of maleic anhydride-grafted polyethylene (average maleic anhydride grafting rate of 1%), 0.2 parts of antioxidant 1010, and 0.1 parts of antioxidant 168.

[0061] The flame-retardant core layer comprises the following components by weight: 21.7 parts of Guangzhou Petrochemical 7042, 0 parts of CNOOC Shell 2420H2, 50 parts of magnesium hydroxide (average particle size of 2μm), 8 parts of maleic anhydride-grafted polyethylene (average maleic anhydride grafting rate of 1%), 0.2 parts of antioxidant 1010, and 0.1 parts of antioxidant 168.

[0062] The adhesive layer is made of Guangzhou Lushan adhesive resin TP101, with a melt index of 3.5 g / 10 min and a Vicat softening point of 75℃.

[0063] The preparation method of the polyolefin flame-retardant and weather-resistant adhesive film in this embodiment includes the following steps: (1) The raw materials required for the first protective layer, the second protective layer and the flame-retardant core layer are mixed evenly by a high-speed mixer according to their respective proportions, and then extruded and granulated by a twin-screw extruder to obtain the first protective layer granules, the second protective layer granules and the flame-retardant core layer granules respectively; wherein, the twin-screw extrusion temperature of the first protective layer granules, the second protective layer granules and the flame-retardant core layer granules is 200℃, the screw speed is 300rpm, the feeding speed is 7Hz, and the twin-screw length-to-diameter ratio L:D=40:1.

[0064] (2) The first protective layer granules, the second protective layer granules, the flame-retardant core layer granules and the adhesive layer granules are co-extruded and cast in multiple layers to obtain a polyolefin flame-retardant and weather-resistant film; wherein, during the multi-layer co-extruded casting, the processing temperatures corresponding to the first protective layer, the second protective layer, the flame-retardant core layer, the adhesive layer and the die head are 190℃, 190℃, 180℃, 150℃ and 180℃, respectively.

[0065] This embodiment provides a polyolefin-coated panel, comprising a galvanized steel sheet (0.6 mm thick) as a metal substrate and polyolefin flame-retardant and weather-resistant adhesive films disposed on its upper and lower surfaces respectively. The preparation method includes: stacking the polyolefin flame-retardant and weather-resistant adhesive film, the galvanized steel sheet, and the polyolefin flame-retardant and weather-resistant adhesive film in that order, with the adhesive layer of the polyolefin flame-retardant and weather-resistant adhesive film facing the galvanized steel sheet; then hot-rolling the composite at 160°C and 0.4 MPa at a composite linear speed of 5 m / min; and finally cooling to obtain the polyolefin-coated panel.

[0066] Example 2 This embodiment is the same as that in Embodiment 1, except that the thickness of the flame-retardant core layer is different.

[0067] In this embodiment, the thickness of the flame-retardant core layer in the polyolefin flame-retardant and weather-resistant adhesive film is 0.08 mm.

[0068] Example 3 This embodiment is the same as that in Embodiment 1, except that the thickness of the flame-retardant core layer is different.

[0069] In this embodiment, the thickness of the flame-retardant core layer in the polyolefin flame-retardant and weather-resistant film is 0.12 mm.

[0070] Example 4 This embodiment is the same as that in Embodiment 1, except that the thickness of the first protective layer and the second protective layer are different.

[0071] In this embodiment, the polyolefin flame-retardant and weather-resistant film has a first protective layer thickness of 0.02 mm and a second protective layer thickness of 0.05 mm.

[0072] Example 5 This embodiment is the same as that in Embodiment 1, except that the thickness of the first protective layer and the second protective layer are different.

[0073] In this embodiment, the thickness of the first protective layer in the polyolefin flame-retardant and weather-resistant film is 0.05 mm, and the thickness of the second protective layer is 0.02 mm.

[0074] Example 6 group This embodiment group refers to Embodiment 1, the only difference being the amount of LyondellBasell Hifax CA1147A and Dow Versify 3200 used in the first protective layer. All other aspects are the same as in Embodiment 1, with the specific differences as follows: Example 6a: 73 copies of LyondellBasell Hifax CA 1147A, 15 copies of Dow Versify 3200; Example 6b: 58 copies of LyondellBasell Hifax CA 1147A, 30 copies of Dow Versify 3200; Example 6c: 88 copies of LyondellBasell Hifax CA 1147A and 0 copies of Dow Versify 3200.

[0075] Example 7 This embodiment is the same as that in Embodiment 1, except that the amount of Dow VERSIFY 2200 and maleic anhydride-grafted polyethylene used in the second protective layer is different. All other aspects are the same as in Embodiment 1.

[0076] In the second protective layer of this embodiment, there are 72.7 parts of Dow VERSIFY 2200 and 2 parts of maleic anhydride-grafted polyethylene (average maleic anhydride grafting rate of 1%).

[0077] Example 8 This embodiment is the same as that in Embodiment 1, except that the amount of Guangzhou Petrochemical 7042 and magnesium hydroxide in the flame-retardant core layer is different.

[0078] In the flame-retardant core layer of this embodiment, there are 31.7 parts of Guangzhou Petrochemical 7042 and 40 parts of magnesium hydroxide.

[0079] Example 9 This embodiment is the same as that in Embodiment 1, except that the material of the adhesive layer is different.

[0080] The adhesive layer in this embodiment is Guangzhou Lushan adhesive resin VB790, with a melt index of 4.3 g / 10min and a Vicat softening point of 70℃.

[0081] Comparative Example 1 Comparative Example 1 is the same as Example 1, except that it does not include the first protective layer and the thickness of the flame-retardant core layer is different.

[0082] In this comparative example, the thickness of the flame-retardant core layer is 0.14 mm.

[0083] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that it does not include a second protective layer and the thickness of the flame-retardant core layer is different.

[0084] In this comparative example, the thickness of the flame-retardant core layer is 0.14 mm.

[0085] Comparative Example 3 Comparative Example 3 is the same as Example 1, except that it does not include an adhesive layer and the thickness of the flame-retardant core layer is different.

[0086] In this comparative example, the thickness of the flame-retardant core layer is 0.12 mm.

[0087] Comparative Example 4 Comparative Example 4 is the same as Example 1, except that the composition of the first protective layer is different, while the rest is the same as Example 1.

[0088] In this comparative example, the first protective layer comprises the following components by weight: 88 parts of Guangzhou Petrochemical 7042, 10 parts of titanium dioxide (average particle size of 0.4 μm), 0.5 parts of calcium stearate (average particle size of 10 μm), 0.6 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 0.4 parts of light stabilizer UV-622, and 0.3 parts of light stabilizer UV-326.

[0089] Comparative Example 5 Comparative Example 5 is the same as Example 1, except that the composition of the second protective layer is different.

[0090] In this comparative example, the second protective layer comprises the following components by weight: 70.7 parts of Guangzhou Petrochemical 7042, 25 parts of magnesium hydroxide (average particle size of 2μm), 4 parts of maleic anhydride-grafted polyethylene (average maleic anhydride grafting rate of 1%), 0.2 parts of antioxidant 1010, and 0.1 parts of antioxidant 168.

[0091] Comparative Example 6 Comparative Example 6 is the same as Example 1, except that the composition of the second protective layer and the flame-retardant core layer is different.

[0092] In this comparative example, the second protective layer comprises the following components by weight: 95.7 parts of Dow VERSIFY 2200, 4 parts of maleic anhydride-grafted polyethylene (average maleic anhydride grafting rate of 1%), 0.2 parts of antioxidant 1010, and 0.1 parts of antioxidant 168; the flame-retardant core layer comprises the following components by weight: 71.7 parts of Guangzhou Petrochemical 7042, 20 parts of CNOOC Shell 2420H, 8 parts of maleic anhydride-grafted polyethylene (average maleic anhydride grafting rate of 1%), 0.2 parts of antioxidant 1010, and 0.1 parts of antioxidant 168.

[0093] Experimental Example The following performance tests were conducted on the polyolefin flame-retardant and weather-resistant adhesive films and polyolefin coated boards of different embodiments and comparative examples. The test results are shown in Table 1.

[0094] 1. Mechanical properties: The polyolefin flame retardant and weather-resistant film was tested according to GB / T 1040.3 standard, with a tensile speed of 100 mm / min.

[0095] 2. 180° peel strength: The polyolefin coated board was tested according to the 180° peel strength test method specified in GB / T 2790-1995 standard, with a peel speed of 100 mm / min.

[0096] 3. Flame retardant performance: The polyolefin coated board was tested according to GB / T 8626 standard; the ignition time was 30s, and the phenomenon of burning drips igniting the filter paper was observed within 60s, as well as the flame tip height within 60s.

[0097] 4. Artificial Climate Accelerated Aging: The polyolefin coated board to be tested was tested according to GB / T 18244-2022 standard. The cumulative radiant energy at a wavelength of 340nm should not be less than 5100kJ / (m²). 2 (nm), the total aging time of the xenon lamp is 6000h; observe for delamination, powdering, peeling and flaking every 500h.

[0098] 5. Film processing performance: During the production process, the polyolefin flame-retardant and weather-resistant film was sampled 5 times, with a sampling interval of more than 10 minutes, and the following tests (1) and (2) were performed: (1) Appearance: Whether there are any abnormalities such as wrinkles or orange peel texture; (2) Mass per unit area: Tested according to GB / T 31729-2015, and the ratio R of the range to the average of the 5 results was recorded and calculated; The processing performance of the adhesive film is evaluated according to the above results: if there are no abnormalities in appearance and R≤5%, it is considered excellent; if there are no abnormalities in appearance and 5%<R≤10%, it is considered good; if there are abnormalities in appearance or R>10%, it is considered poor.

[0099] Table 1 Performance Test Results

[0100] As can be seen from the above test results, the polyolefin flame-retardant and weather-resistant adhesive film of the present invention has both good flame retardancy and excellent weather resistance, and can maintain a long-lasting interfacial bonding strength with the metal substrate.

[0101] Comparing Example 1 and Comparative Example 1, it can be seen that the absence of a first protective layer in the adhesive film severely affects its weather resistance. Comparing Example 1 and Comparative Example 2, it can be seen that the absence of a second protective layer in the adhesive film leads to poor compatibility among the layers, resulting not only in decreased peel strength but also in delamination under accelerated aging in artificial climate conditions.

[0102] Comparing Example 1 and Comparative Example 4, it can be seen that when TPO is not used in the first protective layer, it not only negatively affects the processing performance and mechanical properties of the film, but also leads to a decrease in weather resistance. Comparing Example 1 and Example 6c, when the first polyolefin elastomer is not used in the first protective layer, it affects the compatibility of the components, resulting in a significant decrease in weather resistance and mechanical properties, and delamination occurs after aging.

[0103] Comparing Example 1 with Comparative Example 5, it can be seen that when the second polyolefin elastomer is not used in the second protective layer, a good transition cannot be achieved between the first protective layer and the flame-retardant core layer, the peel strength is greatly reduced, and delamination occurs after aging.

[0104] Comparing Example 1 and Comparative Example 6, it can be seen that when the second protective layer and the flame-retardant core layer do not contain magnesium hydroxide, the film has no flame-retardant effect.

[0105] Comparing Example 1 with Examples 6a and 6b, it can be seen that adjusting the ratio of thermoplastic elastomer to first polyolefin elastomer in the first protective layer within the above-mentioned range is more conducive to the balance between mechanical properties, weather resistance, and processing performance of the first protective layer. When the amount of TPO is too high, it is not conducive to the dispersion of additives such as titanium dioxide, affecting the processing performance of the film; when the amount of TPO is too low, the weather resistance deteriorates.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyolefin flame-retardant and weather-resistant adhesive film, characterized in that, It includes a first protective layer, a second protective layer, a flame-retardant core layer, and an adhesive layer that are stacked sequentially; The first protective layer comprises the following components by weight: 55-80 parts of TPO, 15-35 parts of the first polyolefin elastomer, 5-15 parts of titanium dioxide, 0.1-3 parts of antioxidant, 0.1-3 parts of light stabilizer, and 0.1-3 parts of acid absorber; The second protective layer comprises the following components by weight: 40-75 parts of a second polyolefin elastomer, 20-35 parts of magnesium hydroxide, 2-5 parts of maleic anhydride-grafted polyethylene, and 0.1-3 parts of an antioxidant; The flame-retardant core layer comprises the following components by weight: 30-55 parts polyethylene resin, 40-60 parts magnesium hydroxide, 5-10 parts maleic anhydride-grafted polyethylene, and 0.1-3 parts antioxidant. The adhesive layer comprises a polyolefin adhesive resin grafted with maleic anhydride.

2. The polyolefin flame-retardant and weather-resistant adhesive film according to claim 1, characterized in that, The TPO has a melt index of 0.5~4g / 10min and a melting point of 140~165℃ under the condition of 230℃ / 2.16kg. The melt index of the first polyolefin elastomer under the conditions of 230℃ / 2.16kg is 7~10g / 10min, and the Vicat softening point is 40~65℃.

3. The polyolefin flame-retardant and weather-resistant adhesive film according to claim 1, characterized in that, In the first protective layer, the mass ratio of TPO to the first polyolefin elastomer is (2.5~4):

1.

4. The polyolefin flame-retardant and weather-resistant adhesive film according to claim 1, characterized in that, The melt index of the second polyolefin elastomer under the conditions of 230℃ / 2.16kg is 2~5g / 10min, and the Vicat softening point is 60~95℃.

5. The polyolefin flame-retardant and weather-resistant adhesive film according to claim 1, characterized in that, The grafting rate of the maleic anhydride-grafted polyethylene is 0.5% to 1.5%.

6. The polyolefin flame-retardant and weather-resistant adhesive film according to claim 1, characterized in that, The polyolefin adhesive resin grafted with maleic anhydride has a melt index of 2~5 g / 10 min and a Vicat softening point of 70~85℃ under the conditions of 230℃ / 2.16 kg.

7. The polyolefin flame-retardant and weather-resistant adhesive film according to claim 1, characterized in that, The thickness ratio of the first protective layer, the second protective layer, the flame-retardant core layer and the adhesive layer is (1~3):(1~3):(4~8):

1.

8. The polyolefin flame-retardant and weather-resistant adhesive film according to claim 1, characterized in that, The thickness of the polyolefin flame-retardant and weather-resistant adhesive film is 0.1~0.3mm; The thickness of the first protective layer is 0.02~0.05mm; the thickness of the second protective layer is 0.02~0.05mm; and the thickness of the flame-retardant core layer is 0.08~0.12mm.

9. The method for preparing the polyolefin flame-retardant and weather-resistant adhesive film according to any one of claims 1 to 8, characterized in that, The process includes the following steps: multi-layer co-extrusion casting or blown film casting of the first protective layer material, the second protective layer material, the flame-retardant core layer material and the adhesive layer material to obtain the polyolefin flame-retardant and weather-resistant adhesive film.

10. A coated board, characterized in that, The invention includes a metal substrate and a polyolefin flame-retardant and weather-resistant adhesive film disposed on at least one surface of the metal substrate; the polyolefin flame-retardant and weather-resistant adhesive film is the polyolefin flame-retardant and weather-resistant adhesive film according to any one of claims 1 to 8 or the polyolefin flame-retardant and weather-resistant adhesive film prepared by the preparation method according to claim 9.

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