Plastic-coated metal profile and manufacturing method therefor

Abstract

A plastic-coated metal profile and a manufacturing method therefor. The plastic-coated metal profile comprises a metal core, an adhesive layer, a buffer layer, and a functional layer which are tightly bonded from the inside out; the adhesive layer covers the metal core; the buffer layer covers the adhesive layer; the functional layer covers the buffer layer; the buffer layer and the functional layer are bonded by means of hot melting; the buffer layer and the functional layer are both made of plastic; and the hardness of the buffer layer is lower than that of the functional layer. Compared with common plastic-coated metal profiles, the plastic-coated metal profile has an additional buffer layer, the thermal expansion and contraction of the functional layer can be resiliently absorbed by the buffer layer, the functional layer is not easy to fall off and separate from the buffer layer, the adhesive layer is not easy to crack, and the adhesive strength is high, thereby prolonging the service life. The intermediate buffer layer may be manufactured by using recycled plastic, and due to the presence of the buffer layer, the thickness of the functional layer may be designed to be lower, thereby reducing product costs.

Description

Plastic-coated metal profile and preparation method thereof Technical Field

[0001] The present application relates to the technical field of plastic-coated metal profiles, and more specifically, to a plastic-coated metal profile and a preparation method thereof. Background Art

[0002] Plastic-coated metal profiles are composite profiles that can be used to make equipment support frames, connectors, fences, pergolas, floors, wall panels, grilles, doors and windows, etc. Taking plastic-coated aluminum profiles as an example, they are made by compounding a functional coating layer on the surface of an aluminum alloy substrate by melt extrusion. When preparing plastic-coated aluminum profiles, coating layers with different functions can be selected to prepare functionally rich and beautiful composite profiles. Most of the current plastic-coated aluminum profiles are first coated with a layer of glue on the outer surface of the aluminum alloy, and then coated with a layer of functional material. For cost considerations, the functional layer is generally designed to be thinner. The plastic-coated metal profiles obtained by this scheme are easy to detach from the glue layer and the functional layer is easy to fall off due to the repeated contraction of the functional layer due to heating and cooling, making it difficult for the product to be used normally outdoors for a long time. Summary of the Invention

[0003] In view of the problem that the plastic-coated metal profile is obtained by first coating a layer of glue on the outer surface of the metal core material and then coating it with a layer of functional material, the glue layer is prone to cracking and the functional layer is prone to falling off due to repeated contraction of the functional layer when heated and cooled, thus the service life of the plastic-coated aluminum profile is short. This application proposes a plastic-coated metal profile and a preparation method thereof.

[0004] In a first aspect, the present application proposes a plastic-coated metal profile and adopts the following technical solution.

[0005] A plastic-coated metal profile comprises a metal core, an adhesive layer, a buffer layer, and a functional layer, which are tightly bonded from the inside out. The adhesive layer covers the metal core. The buffer layer covers the adhesive layer. The functional layer covers the buffer layer.

[0006] The buffer layer and the functional layer are combined by hot melting.

[0007] The material of the buffer layer is plastic. The material of the functional layer is plastic. The hardness of the buffer layer is lower than that of the functional layer.

[0008] By adopting the above technical solution, the plastic-coated metal profile has an additional buffer layer compared to the general plastic-coated metal profile. The material of the buffer layer is plastic, and the material of the functional layer is plastic. The buffer layer and the functional layer have a strong bonding force through hot melting, and the hardness of the buffer layer is less than that of the functional layer. The thermal expansion and contraction of the functional layer can be elastically absorbed by the buffer layer, and the functional layer is not easy to fall off and separate from the buffer layer. Since the buffer layer reduces the influence of the thermal expansion and contraction effect of the functional layer on the adhesive layer, the adhesive layer is not easy to fall off, the bonding strength is high, and the service life of the plastic-coated aluminum profile is improved. The middle buffer layer can be made of recycled plastic, and due to the presence of the buffer layer, the thickness of the functional layer can be designed to be lower, thereby reducing product costs. The added buffer layer also improves the impact resistance of the plastic-coated metal profile, can also reduce collision damage, and also has better thermal insulation performance. Among them, the metal core material can be an aluminum alloy.

[0009] As an improvement to the plastic-coated metal profile, the buffer layer and the functional layer have polymers of the same composition, and the polymers each account for 30-100% of the mass of the buffer layer and the functional layer.

[0010] By adopting the above technical solution, the buffer layer and functional layer with the same polymer composition accounting for 30~100% by mass have stronger bonding strength through hot melt and are less likely to separate and fall off.

[0011] As an improvement to the plastic-coated metal profile, the polymer in the buffer layer is recycled material.

[0012] By adopting the above technical solution, waste materials are recycled and reused, which promotes the green development of the industry. The product performance is equivalent to that of the buffer layer prepared with new materials. This measure reduces production costs.

[0013] As an improvement to the plastic-coated metal profile, the polymer in the buffer layer includes HDPE and LDPE. The polymer in the functional layer is HDPE. The sum of the mass percentages of HDPE and LDPE in the buffer layer is ≤ the mass percentage of HDPE in the functional layer.

[0014] In the above technical solution, HDPE (high-density polyethylene) has relatively high hardness and a linear molecular structure, resulting in high toughness and corrosion resistance. LDPE (low-density polyethylene) has relatively low hardness and a softer texture. Its high molecular branching makes it more elastic than HDPE. The hardness of a blend of HDPE and LDPE is lower than that of pure HDPE. Because the combined mass percentage of HDPE and LDPE in the buffer layer is less than the mass percentage of HDPE in the functional layer, the buffer layer is generally harder than the functional layer.

[0015] As an improvement to the plastic-coated metal profile, the buffer layer comprises the following components by mass: 40-60% HDPE, 10-30% LDPE, 20-30% first filler, 1-3% lubricant, and 1-3% additive. The additive is hydrogenated styrene-butadiene block copolymer.

[0016] By adopting the above technical solution, the first filler can reduce the thermal expansion and contraction of the buffer layer. The lubricant can improve the extrusion efficiency of the material in the equipment. The lubricant can include silicone oil and / or fatty acid amide. The hydrogenated styrene-butadiene block copolymer used as an additive can improve the fusion degree of HDPE and LDPE, thereby enhancing the heat resistance and oxidation resistance of the buffer layer.

[0017] As an improvement of the plastic-coated metal profile, the first filler includes wood powder, calcium powder and talcum powder.

[0018] By adopting the above technical solution, wood powder, calcium powder and talcum powder can reduce the shrinkage rate of the buffer layer, so that the buffer layer maintains good reliability.

[0019] As an improvement of the plastic-coated metal profile, the raw materials of the functional layer include the following components in mass fraction: HDPE 70-90%, second filler 5-20%, adhesive 1-3%, anti-aging agent 2-5%, and masterbatch 2-5%.

[0020] By adopting the above technical solution, the high proportion of HDPE gives the functional layer excellent rigidity and corrosion resistance. The adhesive bonds the various components together. The secondary filler reduces the shrinkage of the functional layer. The anti-aging agent enhances the UV resistance of the functional layer. The masterbatch imparts color and other functions to the functional layer. The secondary filler can include one or more of calcium powder, talc, and wood powder. The adhesive can include one or more of SBS, polystyrene, polyacrylate, and epoxy resin. The anti-aging agent can include one or more of benzophenone and benzotriazole.

[0021] As an improvement of the plastic-coated metal profile, the material of the adhesive layer is maleic anhydride grafted polyethylene, the grafting rate of the maleic anhydride grafted polyethylene is 0.8-1.2%, and the thickness of the adhesive layer is 0.15-0.25 mm.

[0022] By adopting the above technical solution, maleic anhydride-grafted polyethylene has good elasticity. By grafting several maleic anhydride molecules onto the polyethylene molecular chain, the product combines the good processability and other excellent properties of polyethylene with the strong polarity of maleic anhydride polar molecules, improving adhesion to the metal core and buffer layer. The bonding layer utilizes maleic anhydride-grafted polyethylene with a grafting ratio of 0.8-1.2%, which is not prone to cracking even under long-term outdoor storage conditions and maintains its bonding effect. If the grafting ratio of the maleic anhydride-grafted polyethylene is too low, the molecular bonding strength is not significantly improved; if the grafting ratio is too high, the bonding layer is prone to cracking and failure. Furthermore, the thickness of the bonding layer is controlled to 0.15-0.25 mm, making the bonding layer of the maleic anhydride-grafted polyethylene less likely to delaminate. If the thickness of the adhesive layer is too low, the bonding force is weak; if the thickness of the adhesive layer is too high, the adhesive layer is easy to debond. Therefore, controlling the thickness of the adhesive layer to 0.15~0.25mm can make the adhesive layer have strong bonding force while not easy to crack.

[0023] On the second aspect, the present application also proposes a method for preparing a plastic-coated metal profile, and adopts the following technical solution.

[0024] A method for preparing a plastic-coated metal profile, using a co-extrusion molding system to prepare the plastic-coated metal profile, the co-extrusion molding system comprising a traction mechanism, a heating mechanism, a mold assembly, a first co-extruder, a second co-extruder, a third co-extruder, and a cooling mechanism. The preparation method comprises:

[0025] Maleic anhydride grafted polyethylene is used as the raw material of the adhesive layer, put into the first co-extruder, and heated to melt.

[0026] Recycled HDPE, recycled LDPE, a first filler, a lubricant and an additive are used as raw materials for the buffer layer, put into the second co-extruder, and heated and melted.

[0027] HDPE, a second filler, an adhesive, an anti-aging agent and a masterbatch are used as raw materials for the functional layer, put into the third co-extruder, and heated and melted.

[0028] The traction mechanism pushes the metal core material forward. During the pushing process, the heating mechanism preheats the metal core material. The metal core material enters the mold assembly. The first co-extruder, the second co-extruder and the third co-extruder sequentially coat the metal core material with an adhesive layer, a buffer layer and a functional layer. The cooling mechanism cools the adhesive layer, the buffer layer and the functional layer to obtain the plastic-coated metal profile.

[0029] By adopting the above technical solution, an adhesive layer, a buffer layer, and a functional layer are sequentially coated on a metal core material using a hot-melt method, followed by cooling and forming. This not only reduces the number of production steps but also significantly improves the peel strength of each layer and the uniformity of the coating. The metal core material can be an aluminum alloy rod, such as a 3-5 meter long aluminum alloy. After cooling, a flaw detection sensing system can accurately identify the cutting port, resulting in a plastic-coated metal profile product of uniform specifications. A special surface polishing treatment is then applied to the final high-strength multi-layer co-extruded profile. The conventional process of first coating the metal profile with an adhesive layer and then with a functional material layer is used. However, during extrusion molding, the long metal core material bends and deforms during the extrusion process, making it difficult to position the metal core. Furthermore, to reduce costs during recycling, the adhesive layer must be retained, requiring the functional layer and adhesive layer to be separated. However, due to the thinness of the functional layer, peeling residue easily remains on the adhesive layer, making it difficult to peel the functional layer for secondary recycling. After the method adds a buffer layer between the adhesive layer and the functional layer, the functional layer can be peeled off more easily without damaging the adhesive layer.

[0030] In summary, the plastic-coated metal profile and its preparation method of the present application have the following beneficial effects:

[0031] Plastic-coated metal profiles are coated with an adhesive layer on the metal core, a buffer layer, and a functional layer on the outside. The addition of a buffer layer is beneficial to the positioning of the profile, and defective products can be processed by grinding and other methods for secondary use.

[0032] Adding a buffer layer significantly reduces the impact of thermal expansion and contraction on the bonding layer, improving adhesion;

[0033] The intermediate buffer can be made of a composite of various recycled plastics and wood powder, which can reduce the thickness of the functional layer and thus reduce product costs;

[0034] It improves the impact resistance and cushioning performance of the product, can reduce damage when it is bumped, and has better heat insulation and thermal insulation functions.

[0035] This application uses multi-layer co-extrusion coating technology. The first coating layer uses high-performance copolymer modified resin, and the other layers use polymer materials. The polymer materials are coated and shaped layer by layer with high-frequency heating, water cooling and air ring cooling, which greatly improves the peel strength and coating uniformity. The metal core material joints use high-temperature resistant end caps and synchronous traction devices to continuously enter the co-extrusion mold for coating. The back end is equipped with an automated flaw detection sensing system that can accurately identify the cutting port and produce plastic-coated metal profile products of uniform specifications. Later, through a special surface polishing treatment method, the final high-strength multi-layer composite co-extruded imitation wood profile is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG1 is a schematic structural diagram of plastic-coated metal profiles prepared using a co-extrusion molding system in some embodiments and comparative examples.

[0037] FIG2 is an image of the test product of Example 1 after being exposed to sunlight outdoors in Test Example 1.

[0038] FIG3 is an appearance image of the test product of Example 2 in Test Example 1 after the high and low temperature cycle test.

[0039] FIG4 is a picture showing the phenomenon that the test product of Comparative Example 1 in Test Example 1 is debonded on all four sides after outdoor exposure test, and the functional layer can be easily peeled off manually.

[0040] FIG5 is a picture showing the shrinkage of the functional layer at the end of the sample of Comparative Example 1 in Test Example 1 after high and low temperature tests.

[0041] FIG6 is a picture showing the shrinkage of the functional layer at the end of the sample of Comparative Example 1 after the boiling water test in Test Example 1. DETAILED DESCRIPTION

[0042] The following describes in detail some embodiments of the plastic-coated metal profile and its preparation method. Example

[0043] Referring to Figure 1, a method for preparing a plastic-coated metal profile is shown, wherein the plastic-coated metal profile is prepared using a co-extrusion molding system. The co-extrusion molding system includes a traction mechanism, a heating mechanism, a mold assembly, a first co-extruder, a second co-extruder, a third co-extruder, and a cooling mechanism. The preparation method includes:

[0044] The adhesive layer material is maleic anhydride-grafted polyethylene, with a grafting ratio of 1.0%. It is first baked at 80°C for 2 hours to remove moisture and reduce the expansion rate of the resulting adhesive layer. The adhesive layer material is then placed in a first coextruder and heated until it melts and becomes liquid.

[0045] Recycled HDPE, recycled LDPE, a first filler, a lubricant, and additives are used as the raw materials for the buffer layer. These are placed in a second coextruder and heated until melted into a liquid state. The first filler is then dispersed in a powdered state within the melt. The weight percentages of the components used in the buffer layer are: 50% HDPE, 20% LDPE, 26% first filler, 2% lubricant, and 2% additive. The additive is hydrogenated styrene-butadiene block copolymer. The first filler comprises 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The lubricant is silicone oil.

[0046] The functional layer materials, HDPE, a secondary filler, an adhesive, an anti-aging agent, and a masterbatch, were placed in a third coextruder and heated until melted into a liquid state. The secondary filler, in powder form, was then dispersed into the melt. The functional layer materials consisted of the following components by weight: 81.6% HDPE, 9.2% secondary filler, 1.8% adhesive, 3.7% anti-aging agent, and 3.7% masterbatch. The secondary filler consisted of 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The adhesive was SBS, and the anti-aging agent was benzophenone.

[0047] The traction mechanism propels the long aluminum alloy rod forward. During this process, the heating mechanism preheats the long rod. The long rod enters the die assembly, where the first, second, and third co-extruders sequentially coat the long rod with an adhesive layer, a buffer layer, and a functional layer. The cooling mechanism cools these layers, resulting in a plastic-coated metal profile. The adhesive layer is 0.20 mm thick, the buffer layer is 2.08 mm thick, and the functional layer is 0.77 mm thick. Example

[0048] Referring to Figure 1, a method for preparing a plastic-coated metal profile is shown, wherein the plastic-coated metal profile is prepared using a co-extrusion molding system. The co-extrusion molding system includes a traction mechanism, a heating mechanism, a mold assembly, a first co-extruder, a second co-extruder, a third co-extruder, and a cooling mechanism. The preparation method includes:

[0049] The adhesive layer is made of maleic anhydride-grafted polyethylene with a grafting ratio of 0.8%. It is first baked at 80°C for 2 hours to remove moisture and reduce the expansion rate of the adhesive layer. The adhesive layer material is then placed in the first coextruder and heated until it melts and becomes liquid.

[0050] Recycled HDPE, recycled LDPE, a first filler, a lubricant, and additives are used as the buffer layer materials. These are placed in a second coextruder and heated until melted into a liquid state. The first filler is then dispersed in a powdered state within the melt. The weight percentages of the buffer layer materials are as follows: 40% HDPE, 30% LDPE, 26% first filler, 1% lubricant, and 3% additives. The additive is hydrogenated styrene-butadiene block copolymer. The first filler comprises 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The lubricant is silicone oil.

[0051] The functional layer materials, HDPE, a secondary filler, an adhesive, an anti-aging agent, and a masterbatch, are placed in a third coextruder and heated until melted into a liquid state. The secondary filler, in powder form, is then dispersed into the melt. The functional layer materials consist of the following components by weight: 90% HDPE, 5% secondary filler, 1% adhesive, 2% anti-aging agent, and 2% masterbatch. The secondary filler comprises 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The adhesive is epoxy resin, and the anti-aging agent is benzophenone.

[0052] The traction mechanism propels the long aluminum alloy rod forward. During this process, the heating mechanism preheats the long rod. The long rod enters the die assembly, where the first, second, and third co-extruders sequentially coat the long rod with an adhesive layer, a buffer layer, and a functional layer. The cooling mechanism cools these layers, resulting in a plastic-coated metal profile. The adhesive layer is 0.16mm thick, the buffer layer is 2.24mm thick, and the functional layer is 0.63mm thick. Example

[0053] Referring to Figure 1, a method for preparing a plastic-coated metal profile is shown, wherein the plastic-coated metal profile is prepared using a co-extrusion molding system. The co-extrusion molding system includes a traction mechanism, a heating mechanism, a mold assembly, a first co-extruder, a second co-extruder, a third co-extruder, and a cooling mechanism. The preparation method includes:

[0054] The adhesive layer is made of maleic anhydride-grafted polyethylene with a grafting ratio of 1.2%. It is first baked at 80°C for 2 hours to remove moisture and reduce the expansion rate of the adhesive layer. The adhesive layer material is then placed in the first coextruder and heated until it melts and becomes liquid.

[0055] Recycled HDPE, recycled LDPE, a first filler, a lubricant, and additives are used as the buffer layer materials. These are placed in a second coextruder and heated until melted into a liquid state. The first filler is then dispersed in a powdered state within the melt. The weight percentages of the buffer layer materials are: 60% HDPE, 10% LDPE, 26% first filler, 3% lubricant, and 1% additive. The additive is hydrogenated styrene-butadiene block copolymer. The first filler comprises 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The lubricant is fatty acid amide.

[0056] The functional layer materials, HDPE, a secondary filler, an adhesive, an anti-aging agent, and a masterbatch, were placed in a third coextruder and heated until melted into a liquid state. The secondary filler, in powder form, was then dispersed into the melt. The functional layer materials consisted of the following components by weight: 70% HDPE, 17% secondary filler, 3% adhesive, 5% anti-aging agent, and 5% masterbatch. The secondary filler consisted of 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The adhesive was polyacrylate, and the anti-aging agent was benzotriazole.

[0057] The traction mechanism propels the long rod of aluminum alloy forward. During this process, the heating mechanism preheats the long rod. The long rod then enters the die assembly. The first, second, and third co-extruders sequentially coat the long rod with an adhesive layer, a buffer layer, and a functional layer. The cooling mechanism cools these layers, resulting in a plastic-coated metal profile. The adhesive layer is 0.24mm thick, the buffer layer is 2.13mm thick, and the functional layer is 0.71mm thick.

[0058] Comparative Example 1

[0059] Compared with Example 1, the buffer layer is eliminated in this comparative example. The specific method for preparing a plastic-coated metal profile is as follows.

[0060] A method for preparing a plastic-coated metal profile uses a co-extrusion molding system to prepare the plastic-coated metal profile. The co-extrusion molding system includes a traction mechanism, a heating mechanism, a mold assembly, a first co-extruder, a second co-extruder, and a cooling mechanism. The preparation method includes:

[0061] The adhesive layer material is maleic anhydride-grafted polyethylene, with a grafting ratio of 1.0%. It is first baked at 80°C for 2 hours to remove moisture and reduce the expansion rate of the resulting adhesive layer. The adhesive layer material is then placed in a first coextruder and heated until it melts and becomes liquid.

[0062] HDPE, a secondary filler, an adhesive, an antioxidant, and a masterbatch are placed in a second coextruder and heated until a liquid state is formed. The secondary filler is then dispersed in a powdered state within the melt. The functional layer comprises the following components by weight: 81.6% HDPE, 9.2% secondary filler, 1.8% adhesive, 3.7% antioxidant, and 3.7% masterbatch. The secondary filler comprises 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The adhesive is SBS, and the antioxidant is benzophenone.

[0063] The traction mechanism propels the long aluminum alloy rod forward. During this process, the heating mechanism preheats the rod, which then enters the die assembly. The first and second co-extruders sequentially coat the rod with an adhesive layer and a functional layer. The cooling mechanism cools these layers, resulting in a plastic-coated metal profile. The adhesive layer is 0.20 mm thick, and the functional layer is 0.77 mm thick.

[0064] Comparative Example 2

[0065] This comparative example adopts a technical solution basically the same as that of Example 1 to prepare a plastic-coated metal profile, the only difference being that the thickness of the adhesive layer in this comparative example is 0.10 mm.

[0066] Comparative Example 3

[0067] This comparative example adopts a technical solution basically the same as that of Example 1 to prepare a plastic-coated metal profile, the only difference being that the thickness of the adhesive layer in this comparative example is 0.5 mm.

[0068] Comparative Example 4

[0069] This comparative example adopts a technical solution basically the same as that of Example 1 to prepare a plastic-coated metal profile, and also uses maleic anhydride grafted polyethylene as the raw material for the adhesive layer. The only difference is that the grafting rate of the maleic anhydride grafted polyethylene in this comparative example is 2.5%.

[0070] Comparative Example 5

[0071] This comparative example adopts a technical solution basically the same as that of Example 1 to prepare a plastic-coated metal profile, the only difference being that the raw material of the bonding layer used in this comparative example is thread glue.

[0072] Comparative Example 6

[0073] This comparative example adopts a technical solution basically the same as that of Example 1 to prepare a plastic-coated metal profile. The only difference is that the auxiliary agent used in the buffer layer raw material of this comparative example is ethylene-acrylic acid copolymer.

[0074] Test Example 1

[0075] The plastic-coated metal profiles prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to the tests shown in Table 1 below.

[0076] Table 1 Performance test of plastic-coated metal profiles

[0077] Test items: Outdoor exposure, high and low temperature cycling, boiling water peel strength Test conditions / implementation standards Internal testing, 30cm long test specimen, direct outdoor exposure GB / T 22412-2016GB / T 22412-2016, the standard is to boil water for 2 hours, and the actual boiling time is 72 hours. GB / T2790-1995 Example 1: No debonding after 60 days of testing, no other obvious changes. Appearance: No obvious change. Peel strength decrease rate: 4.2%. The functional layer and the buffer layer have no shrinkage phenomenon, no debonding, and no other obvious changes in appearance. 5.6KN / m. Example 2: No debonding after 60 days of testing, no other obvious changes. Appearance: No obvious change. Peel strength decrease rate: 6.5%. The functional layer and the buffer layer have no shrinkage phenomenon, no debonding, and no other obvious changes in appearance. 5.2KN / m. Example 3: No debonding after 60 days of testing, no other obvious changes. Appearance: No obvious change. Peel strength decrease rate: 7.3%. The functional layer and the buffer layer have no shrinkage phenomenon, no debonding, and no other obvious changes in appearance. 5.1KN / m. Comparative Example 1: Debonding on all sides after 30 days of testing, the longest being 27mm, and the functional layer can be easily peeled off manually. Appearance: The functional layer shrinks, and the debonding length is about 10.0mm. Peel strength decrease rate: 15.3% Functional layer shrinkage, debonding, functional layer peeling 4.2KN / m Comparative Example 2 had slight debonding after 45 days of testing, the debonding length was 2mm, and there was no other obvious change Appearance: the debonding length was about 3.1mm Peel strength decrease rate: 9.8% The functional layer and the buffer layer had no shrinkage, no debonding, and no other obvious changes in appearance 4.8KN / m Comparative Example 3 had slight debonding after 60 days of testing, the debonding length was 1.3mm, and there was no other obvious changes Appearance: the functional layer shrank, and the debonding length was about 1.6mm; Peel strength decrease rate: 11.5% The functional layer and the buffer layer had no shrinkage, no debonding, and no other obvious changes in appearance 5.3KN / m Comparative Example 4 had debonding on all sides after 30 days of testing, the longest being 19mm Appearance: cracks appeared in the adhesive layer, and the debonding length was about 8.1mm; Peel strength decrease rate: 13.8% There is no shrinkage in the functional layer and the buffer layer, no debonding, and no other obvious changes in appearance. 4.8KN / m Comparative Example 5 has slight debonding after 10 days of testing, with a debonding length of 4mm and no other obvious changes. Appearance: Debonding length is about 7mm. Peel strength decrease rate: 56.3% There is no shrinkage in the functional layer and the buffer layer, and the debonding length is about 6mm. 2.5KN / m Comparative Example 6 has slight cracking in the buffer layer after 10 days of testing, and no other obvious changes. Appearance: The buffer layer has slight cracking. Peel strength decrease rate: 25.5% There is no shrinkage in the functional layer and the buffer layer, and cracking occurs in the buffer layer. There is no obvious change in other appearance. 4.8KN / m Comparative Example 7 The adhesive layer detaches from the aluminum alloy after 7 days of testing: The functional layer shrinks, the debonding length is 10.5mm, and the peel strength decreases by 25.3%. There is no shrinkage in the functional layer and the buffer layer, no debonding, and no obvious changes in other appearance. 5.0KN / m

[0078] Among them, the outdoor exposure, high and low temperature cycle, boiling water and peel strength tests in Table 1 were all conducted using new materials that had not been tested before.

[0079] The peel strength test in Table 1 is the initial peel strength of the test piece without other tests. The test piece without buffer layer is used to test the peel strength of the functional layer. The others are used to test the peel strength of the integrated functional layer and buffer layer.

[0080] From the results in Table 1, it can be seen that the plastic-coated metal profiles prepared in Examples 1-3 have good resistance to strong light, resistance to high and low temperature impact, resistance to boiling water, and high peeling strength. Figure 2 is an image of the test product of Example 1 after outdoor exposure, showing that there is no obvious change at its outer end, no debonding, and no shrinkage of the buffer layer and the functional layer. The plastic-coated metal profiles prepared in Examples 1-3 can be used outdoors for a long time and maintain their effectiveness. Figure 3 is an image of the appearance of the test product of Example 2 after the high and low temperature cycle test, showing that there is no shrinkage of the buffer layer and the functional layer. It should be noted that the shrinkage of the buffer layer and the functional layer is mainly reflected at the end of the test product. Check whether the metal core material is exposed. If the metal at the end is exposed, it indicates that the buffer layer and the functional layer have obvious shrinkage. If the metal at the end is not exposed, it indicates that the buffer layer and the functional layer have no obvious shrinkage.

[0081] In comparison, the sample in Comparative Example 1 lacks a buffer layer and is prone to debonding under strong light, high- and low-temperature impact conditions. It has a short outdoor service life and its low peel strength also makes it prone to debonding, with the functional layer prone to shrinkage. Figure 4 shows the sample in Comparative Example 1 debonding on all four sides after an outdoor exposure test, with the functional layer easily peeled off manually. Figure 5 shows the sample in Comparative Example 1 after undergoing a high- and low-temperature test, with the functional layer shrinking at the end, and the metal core material exposed when viewed from the side. Figure 6 shows the sample in Comparative Example 1 after undergoing a boiling water test, with the functional layer shrinking at the end, and the metal core material exposed when viewed from the side. The sample in Comparative Example 2 has an adhesive layer that is too thin, making it prone to debonding, and its peel strength is slightly lower than that of the samples in Examples 1-3. The sample in Comparative Example 3 has an adhesive layer that is too thick, which also makes it prone to debonding. The grafting rate of maleic anhydride-grafted polyethylene in Comparative Example 4 is 2.5%, which is too high. The adhesive layer suffers from melt fracture and cannot form a continuous phase, causing the adhesive layer to debond easily. The adhesive layer material used in the sample of Comparative Example 5 was thread glue. When used in the plastic-coated metal profile of this solution, it easily debonded and had weak peel strength, indicating weak adhesion to the buffer layer. The buffer layer material used in the sample of Comparative Example 6 was an ethylene-acrylic acid copolymer additive. After outdoor exposure and high-low temperature cycling tests, the buffer layer showed slight cracking. This is because the ethylene-acrylic acid copolymer additive did not significantly improve the heat resistance and oxidation resistance of the buffer layer compared to hydrogenated styrene-butadiene block copolymer.

[0082] Test Example 2

[0083] Referring to the preparation method of Example 1, the buffer layer material and the functional layer material were prepared separately, and then the hardness of the buffer layer material and the functional layer material was tested, as follows.

[0084] Preparation of the buffer layer material: Recycled HDPE, recycled LDPE, a first filler, a lubricant, and additives are used as the buffer layer raw materials. These are heated until melted into a liquid state, and the first filler is dispersed in the melt in powder form. The weight percentages of the components in the buffer layer raw materials are: 50% HDPE, 20% LDPE, 26% first filler, 2% lubricant, and 2% additive. The additive is hydrogenated styrene-butadiene block copolymer. The first filler comprises 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The lubricant is silicone oil.

[0085] Preparation of the functional layer material: HDPE, a secondary filler, an adhesive, an antioxidant, and a masterbatch were heated to a molten liquid state. The secondary filler was then dispersed in a powdered state within the melt. The functional layer materials consisted of the following components (by weight): 81.6% HDPE, 9.2% secondary filler, 1.8% adhesive, 3.7% antioxidant, and 3.7% masterbatch. The secondary filler consisted of 1 / 3 wood flour, 1 / 3 calcium powder, and 1 / 3 talc. The adhesive was SBS, and the antioxidant was benzophenone.

[0086] Hardness test: The Brinell hardness of the buffer layer is 54.2 MPa, and the Brinell hardness of the functional layer is 63.7 MPa. The Brinell hardness of the buffer layer is lower than that of the functional layer.

[0087] Combining the above embodiments and comparative examples, the embodiment uses a four-layer coating structure, with aluminum alloy as the base material layer, coated with an adhesive layer, then coated with a buffer layer, and the outermost coated with a functional layer. Compared with the plastic-coated aluminum profile without a buffer layer, adding a buffer layer has the following advantages: from the extrusion process, it is beneficial to the positioning of the profile. This is because when the aluminum alloy of several meters in length is pushed forward, there is a slight deviation from the center position, which will cause the thickness of the outer coating to be uneven, or even lack of material. The buffer layer can cover the slight deviation and slight bending deformation of the aluminum alloy in the length direction, which is helpful for the centering of the aluminum profile and reduces the uneven thickness and lack of material of the functional layer; if defective products are produced, they can be processed by grinding and other methods for secondary utilization; the influence of thermal expansion and contraction effects on the adhesive layer is significantly reduced, and the bonding effectiveness is improved; the middle buffer layer can be prepared using a variety of recycled plastics, wood powder, etc., and the thickness of the functional layer with high material cost can be designed to be relatively thin, thereby reducing product cost; the impact resistance of the product is improved, collision damage can be reduced, and it has better thermal insulation function.

[0088] Aluminum alloys are chemically active and easily oxidized. The above embodiments coat the surface of the aluminum alloy long rod with an adhesive layer, a buffer layer, and a functional layer, providing protection for the aluminum alloy. This not only improves the profile's corrosion resistance but also its heat resistance. It also enhances the profile's surface, making the product more aesthetically pleasing and increasing its commercial value.

[0089] The above are only some embodiments of the present application. The scope of protection of the present application is not limited to the above embodiments. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the creative design of the present application should also fall within the scope of protection of the present application.

Claims

1. A plastic-coated metal profile, characterized in that, It includes a metal core material, an adhesive layer, a buffer layer, and a functional layer that are tightly adhered from the inside out; the adhesive layer covers the metal core material; the buffer layer covers the adhesive layer; the functional layer covers the buffer layer; The buffer layer and the functional layer are combined by a hot-melt method; The material of the buffer layer is plastic; the material of the functional layer is plastic; the hardness of the buffer layer is less than that of the functional layer.

2. The plastic-coated metal profile according to claim 1, wherein The buffer layer and the functional layer have polymers with the same composition; the polymer accounts for 30-100% of the mass of the buffer layer and the functional layer respectively.

3. The plastic-coated metal profile according to claim 2, characterized in that, The polymer in the buffer layer is recycled material.

4. The plastic-coated metal profile according to claim 2, wherein In the buffer layer, the polymer includes HDPE and LDPE; in the functional layer, the polymer is HDPE; the sum of the mass percentages of HDPE and LDPE in the buffer layer ≤ the mass percentage of HDPE in the functional layer.

5. The plastic-coated metal profile according to any one of claims 1 to 4, characterized in that, The raw materials of the buffer layer include the following components by mass fraction: 40-60% HDPE, 10-30% LDPE, 20-30% first filler, 1-3% lubricant, 1-3% additive; the additive is a hydrogenated styrene-butadiene block copolymer.

6. The plastic-coated metal profile according to claim 5, characterized in that, The first filler includes wood powder, calcium powder, and talc powder.

7. The plastic-coated metal profile according to any one of claims 1 to 4, characterized in that, The raw materials of the functional layer include the following components by mass fraction: 70-90% HDPE, 5-20% second filler, 1-3% adhesive, 2-5% anti-aging agent, 2-5% color masterbatch.

8. The plastic-coated metal profile according to claim 1, characterized in that, The material of the adhesive layer is maleic anhydride grafted polyethylene, the grafting rate of the maleic anhydride grafted polyethylene is 0.8-1.2%, and the thickness of the adhesive layer is 0.15-0.25 mm.

9. A preparation method of a plastic-coated metal profile, characterized in that, A co-extrusion molding system is used to prepare the plastic-coated metal profile. The co-extrusion molding system includes a traction mechanism, a heating mechanism, a die assembly, a first co-extruder, a second co-extruder, a third co-extruder, and a cooling mechanism; the preparation method includes: Using maleic anhydride grafted polyethylene as the raw material of the adhesive layer, putting it into the first co-extruder, and heating and melting it; Using recycled HDPE, recycled LDPE, the first filler, the lubricant, and the additive as the raw materials of the buffer layer, putting them into the second co-extruder, and heating and melting them; Using HDPE, the second filler, the adhesive, the anti-aging agent, and the color masterbatch as the raw materials of the functional layer, putting them into the third co-extruder, and heating and melting them; The traction mechanism pushes the metal core material forward. During the pushing process, the heating mechanism preheats the metal core material. The metal core material enters the die assembly, and the first co-extruder, the second co-extruder, and the third co-extruder sequentially coat the adhesive layer, the buffer layer, and the functional layer on the metal core material. The cooling mechanism cools the adhesive layer, the buffer layer, and the functional layer to obtain the plastic-coated metal profile.

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