A plastic clad metal profile and a method of making the same

Abstract

The application relates to the technical field of plastic-wrapped metal profiles, and particularly discloses a plastic-wrapped metal profile and a preparation method thereof. The plastic-wrapped metal profile comprises a metal core material, a bonding layer, a buffer layer and a functional layer which are tightly bonded from inside to outside. The bonding layer covers the metal core material. The buffer layer covers the bonding layer. The functional layer covers the buffer layer. The buffer layer and the functional layer are combined through a hot melting mode. The materials of the buffer layer and the functional layer are plastic. The hardness of the buffer layer is smaller than that of the functional layer. Compared with general plastic-wrapped metal profiles, the plastic-wrapped metal profile has an additional buffer layer, the thermal expansion and cold shrinkage of the functional layer can be elastically absorbed by the buffer layer, the functional layer is not easy to fall off and separate from the buffer layer, the bonding layer is not easy to crack, the bonding firmness is high, and the service life of the plastic-wrapped aluminum profile is prolonged. The recycled plastic can be used to prepare the intermediate buffer layer, and due to the existence of the buffer layer, the thickness of the functional layer can be designed to be lower, so that the product cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plastic-wrapped metal profiles, and more particularly to a plastic-wrapped metal profile and a preparation method thereof. BACKGROUND

[0002] A plastic-wrapped metal profile is a composite profile that can be used to make support frames, connecting pieces, fences, corridor frames, floors, wall panels, grilles, or doors and windows of equipment. Taking a plastic-wrapped aluminum profile as an example, it is made by compounding a functional cladding layer on the surface of an aluminum alloy substrate by means of melt extrusion. When the plastic-wrapped aluminum profile is compounded, a cladding layer with different functions can be selected to prepare a composite profile with rich functions and good appearance. At present, most plastic-wrapped aluminum profiles are first coated with a layer of adhesive on the outer surface of the aluminum alloy, and then coated with a layer of functional material. Due to cost considerations, the functional layer is generally designed to be thin. The plastic-wrapped metal profile obtained by using this scheme is prone to have the adhesive layer separated and the functional layer fall off due to repeated shrinkage of the functional layer under cold and heat, and the product is difficult to be used normally for a long time outdoors. SUMMARY

[0003] In view of the problem that the plastic-wrapped metal profile obtained by first coating a layer of adhesive on the outer surface of the metal core material and then coating a layer of functional material is prone to have the adhesive layer cracked and the functional layer fallen off due to repeated shrinkage of the functional layer under cold and heat, and the service life of the plastic-wrapped aluminum profile is relatively short, the present application provides a plastic-wrapped metal profile and a preparation method thereof.

[0004] In a first aspect, the present application provides a plastic-wrapped metal profile, and adopts the following technical scheme.

[0005] A plastic-wrapped metal profile includes a metal core material, an adhesive layer, a buffer layer, and a functional layer that are tightly bonded from inside to outside. The adhesive layer coats the metal core material. The buffer layer coats the adhesive layer. The functional layer coats the buffer layer.

[0006] The buffer layer and the functional layer are combined by a hot melt method.

[0007] 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.

[0008] By adopting the technical scheme, compared with general plastic-coated metal profiles, the plastic-coated metal profile is provided with a buffer layer, the material of the buffer layer is plastic, the material of the functional layer is plastic, the buffer layer and the functional layer are combined by hot melting, the hardness of the buffer layer is less than that of the functional layer, the thermal expansion and cold shrinkage of the functional layer can be elastically absorbed by the buffer layer, and the functional layer is not easy to separate from the buffer layer. Since the buffer layer reduces the influence of the thermal expansion and cold shrinkage of the functional layer on the adhesive layer, the adhesive layer is not easy to separate, the adhesion is high, and the service life of the plastic-coated aluminum profile is improved. The intermediate buffer layer can be prepared by using 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 the product cost. The added buffer layer also improves the impact resistance of the plastic-coated metal profile, reduces the damage caused by impact, and has better heat insulation performance. The metal core material can be an aluminum alloy.

[0009] As an improvement of the plastic-coated metal profile, the buffer layer and the functional layer have the same polymer composition. The polymer accounts for 30-100% of the mass of the buffer layer and the functional layer.

[0010] By adopting the technical scheme, the buffer layer and the functional layer have the same polymer composition with a mass ratio of 30-100%, and the combination by hot melting is stronger and less likely to separate.

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

[0012] By adopting the technical scheme, recycled waste is reused, promoting green development of the industry, and the performance of the product is equivalent to that of the buffer layer prepared by using new materials. This measure reduces production costs.

[0013] As an improvement of the plastic-coated metal profile, 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 is less than or equal to the mass percentage of HDPE in the functional layer.

[0014] By adopting the technical scheme, HDPE (high-density polyethylene) has relatively high hardness, linear molecular structure, high toughness and corrosion resistance. LDPE (low-density polyethylene) has relatively low hardness and soft texture, and low-density polyethylene has more molecular branches, making its elasticity better than that of HDPE. The hardness of the mixture of HDPE and LDPE is less than that of pure HDPE, and since the sum of the mass percentages of HDPE and LDPE in the buffer layer is less than or equal to the mass percentage of HDPE in the functional layer, the hardness of the buffer layer is generally less than that of the functional layer.

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

[0016] By adopting the above technical solution, the first filler can reduce the thermal expansion and contraction range 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 as an auxiliary agent can improve the fusion degree of HDPE and LDPE, and improve the heat resistance and oxidation resistance of the buffer layer.

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

[0018] By adopting the above technical solution, the wood powder, calcium powder, and talc 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 material of the functional layer comprises the following components in mass fraction: HDPE 70-90%, second filler 5-20%, adhesive 1-3%, anti-aging agent 2-5%, and color masterbatch 2-5%.

[0020] By adopting the above technical solution, the high proportion of HDPE makes the functional layer have good rigidity and corrosion resistance. The adhesive bonds the components. The second filler can reduce the shrinkage rate of the functional layer. The anti-aging agent can improve the anti-UV effect of the functional layer. The color masterbatch gives the functional layer color and other functions. The second filler can include one or more of calcium powder, talc powder, 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 technical scheme, the maleic anhydride grafted polyethylene has good elasticity, a plurality of maleic anhydride molecules are connected on the polyethylene molecular chain, the product has good processability and other excellent properties of polyethylene, and has strong polarity of maleic anhydride polar molecules, thereby improving the adhesion of the metal core material and the buffer layer. The adhesion layer adopts the maleic anhydride grafted polyethylene with a grafting rate of 0.8-1.2%, and is not easy to crack even under outdoor conditions for a long time, and can continuously maintain the adhesion effect. If the grafting rate of the maleic anhydride grafted polyethylene is too low, the molecular adhesion is not obviously improved; if the grafting rate of the maleic anhydride grafted polyethylene is too high, the adhesion layer is easy to crack and fail. In addition, the thickness of the adhesion layer is controlled to be 0.15-0.25 mm, so that the adhesion layer of the maleic anhydride grafted polyethylene is not easy to open glue. If the thickness of the adhesion layer is too low, the adhesion is weak; if the thickness of the adhesion layer is too high, the adhesion layer is easy to open glue, therefore, the thickness of the adhesion layer is controlled to be 0.15-0.25 mm, so that the adhesion layer has strong adhesion and is not easy to crack.

[0023] In a second aspect, the application further provides a preparation method of the plastic-coated metal profile, and adopts the following technical scheme.

[0024] The preparation method of the plastic-coated metal profile uses a co-extrusion molding system to prepare the plastic-coated metal profile, and the co-extrusion molding system includes a traction mechanism, a heating mechanism, a mold assembly, a first co-extrusion machine, a second co-extrusion machine, a third co-extrusion machine and a cooling mechanism. The preparation method includes:

[0025] The maleic anhydride grafted polyethylene is used as the adhesion layer raw material, and is put into the first co-extrusion machine and heated and melted.

[0026] The recycled HDPE, the recycled LDPE, the first filler, the lubricant and the auxiliary agent are used as the buffer layer raw material, and are put into the second co-extrusion machine and heated and melted.

[0027] The HDPE, the second filler, the adhesive, the anti-aging agent and the color masterbatch are used as the functional layer raw material, and are put into the third co-extrusion machine and heated and melted.

[0028] The traction mechanism pushes the metal core material forward, the heating mechanism preheats the metal core material in the pushing process, the metal core material enters the mold assembly, the first co-extrusion machine, the second co-extrusion machine and the third co-extrusion machine successively coat the adhesion layer, the buffer layer and the functional layer on the metal core material, and the cooling mechanism cools the adhesion layer, the buffer layer and the functional layer to obtain the plastic-coated metal profile.

[0029] By adopting the technical scheme, the adhesion layer, the buffer layer and the functional layer are sequentially coated on the metal core material in a hot melting manner and are cooled and formed, so that the preparation steps are less, and the peeling strength and the uniformity of coating are significantly improved. The metal core material can be an aluminum alloy rod, such as an aluminum alloy with a length of 3-5 meters. After cooling, the cutting port can be accurately identified through a flaw detection induction system, and a plastic-coated metal profile product with a uniform specification is manufactured. Through special surface polishing treatment, a final high-strength multi-layer composite co-extrusion profile is obtained. In the general process of coating a layer of adhesive layer on the outer surface of the metal profile and then coating a layer of functional material, during the extrusion forming, the long strip-shaped metal core material is difficult to position due to the bending deformation and other reasons. In order to reduce the cost, the adhesion layer needs to be reserved during recycling, so the functional layer and the adhesion layer need to be separated. Since the functional layer is thin, it is easy to be left on the adhesion layer during peeling, and it is difficult to peel off the functional layer for secondary recycling. After the buffer layer is added between the adhesion layer and the functional layer, the functional layer can be easily peeled off without damaging the adhesion layer.

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

[0031] The plastic-coated metal profile coats an adhesion layer on the metal core material, then coats a buffer layer, and coats a functional layer on the outermost surface. The addition of the buffer layer facilitates the positioning of the profile, and for defective products, polishing and other methods can be used for secondary utilization. The addition of the buffer layer significantly reduces the influence of thermal expansion and cold contraction on the adhesion layer, and improves the adhesion.

[0032] The intermediate buffer can be made of various recycled plastics, wood powder composites, etc., which can reduce the thickness of the functional layer and thus reduce the cost of the product.

[0033] The impact resistance and cushioning performance of the product are improved, the damage caused by impact can be reduced, and the product has excellent heat insulation and heat preservation functions.

[0034] The application uses a high-performance copolymer modified resin for the first coating layer and a high molecular material for the other layers, and uses high-frequency heating, water cooling and air ring cooling to coat and shape the high molecular material layer by layer, thereby greatly improving the peeling strength and the uniformity of coating. The metal core material joint uses a high-temperature resistant end cap in combination with a synchronous traction device to continuously enter the co-extrusion die for coating, and the rear end is matched with an automatic flaw detection induction system to accurately identify the cutting port and manufacture a plastic-coated metal profile product with a uniform specification. Through special surface polishing treatment, a final high-strength multi-layer composite co-extrusion wood-like profile is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1Schematic diagrams of the structures used in some embodiments and comparative examples to prepare plastic-coated metal profiles using a co-extrusion molding system.

[0036] Figure 2 This is an image of the test sample from Example 1 after it has been exposed to sunlight outdoors.

[0037] Figure 3 The image shows the appearance of the test sample in Example 2 of Test Example 1 after high and low temperature cycling test.

[0038] Figure 4 The image shows the phenomenon in Test Example 1 where the test sample of Comparative Example 1 was exposed to outdoor sunlight and the adhesive on all four sides came unglued, and the functional layer could be easily peeled off manually.

[0039] Figure 5 This is an image showing the phenomenon of functional layer shrinkage at the end of the test specimen in Comparative Example 1 after high and low temperature testing, as seen in Test Example 1.

[0040] Figure 6 This is an image showing the phenomenon of functional layer shrinkage at the end of the test sample in Comparative Example 1 after it has undergone a boiling water test, as seen in Test Example 1. Detailed Implementation

[0041] The following are specific examples of plastic-coated metal profiles and their preparation methods.

[0042] Example 1

[0043] refer to Figure 1 A method for preparing a plastic-coated metal profile, comprising using a co-extrusion molding system, the co-extrusion molding system including 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:

[0044] Maleic anhydride-grafted polyethylene was used as the adhesive layer material, with a grafting rate of 1.0%. The material was 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 was then placed in the first co-extruder and heated until it melted and became liquid.

[0045] Recycled HDPE, recycled LDPE, a first filler, lubricant, and additives are used as the buffer layer raw materials. These are fed into a second co-extruder and heated until molten and liquid. The first filler is dispersed in the melt as a powder. The mass percentages of the components in the buffer layer raw materials are: HDPE 50%, LDPE 20%, first filler 26%, lubricant 2%, and additives 2%. The additive is a 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 raw materials, including HDPE, second filler, adhesive, anti-aging agent and color masterbatch, are put into the third co-extrusion machine and heated to melt into liquid state, and the second filler is dispersed in the molten liquid in powder state. The functional layer raw materials include the following components with mass fraction: HDPE 81.6%, second filler 9.2%, adhesive 1.8%, anti-aging agent 3.7%, and color masterbatch 3.7%. The second filler includes 1 / 3 wood powder, 1 / 3 calcium powder and 1 / 3 talcum powder. The adhesive is SBS. The anti-aging agent is benzophenone.

[0047] The traction mechanism pushes the long rod aluminum alloy forward, and the heating mechanism preheats the long rod aluminum alloy during the pushing process. The long rod aluminum alloy enters the mold assembly, and the first co-extrusion machine, the second co-extrusion machine and the third co-extrusion machine successively coat the adhesive layer, the buffer layer and the functional layer on the long rod aluminum alloy. The cooling mechanism cools the adhesive layer, the buffer layer and the functional layer to obtain a plastic-wrapped metal profile. The thickness of the adhesive layer is 0.20 mm, the thickness of the buffer layer is 2.08 mm, and the thickness of the functional layer is 0.77 mm.

[0048] Example 2

[0049] Reference Figure 1 A method for preparing a plastic-wrapped metal profile using a co-extrusion molding system, the co-extrusion molding system including a traction mechanism, a heating mechanism, a mold assembly, a first co-extrusion machine, a second co-extrusion machine, a third co-extrusion machine and a cooling mechanism. The preparation method includes:

[0050] Maleic anhydride grafted polyethylene is used as the adhesive layer raw material, and the grafting rate of the maleic anhydride grafted polyethylene is 0.8%. First, bake at 80°C for 2 hours to remove moisture to reduce the swelling rate of the prepared adhesive layer. The adhesive layer raw material is put into the first co-extrusion machine and heated to melt into liquid state.

[0051] Recycled HDPE, recycled LDPE, first filler, lubricant and auxiliary agent are used as the buffer layer raw materials, which are put into the second co-extrusion machine and heated to melt into liquid state, and the first filler is dispersed in the molten liquid in powder state. Among them, the mass percentage of each component of the buffer layer raw materials is: HDPE 40%, LDPE 30%, first filler 26%, lubricant 1%, and auxiliary agent 3%. The auxiliary agent is hydrogenated styrene-butadiene block copolymer. The first filler includes 1 / 3 wood powder, 1 / 3 calcium powder and 1 / 3 talcum powder. The lubricant is silicone oil.

[0052] The functional layer raw materials, including HDPE, second filler, adhesive, anti-aging agent and color masterbatch, are put into the third co-extrusion machine and heated to melt into liquid state. The second filler is dispersed in the molten liquid in powder state. The functional layer raw materials include the following components with mass fraction: HDPE 90%, second filler 5%, adhesive 1%, anti-aging agent 2%, and color masterbatch 2%. The second filler includes 1 / 3 wood powder, 1 / 3 calcium powder and 1 / 3 talcum powder. The adhesive is epoxy resin. The anti-aging agent is benzophenone.

[0053] The traction mechanism pushes the long rod aluminum alloy forward, and the heating mechanism preheats the long rod aluminum alloy during the pushing process. The long rod aluminum alloy enters the mold assembly, and the first co-extrusion machine, the second co-extrusion machine and the third co-extrusion machine successively coat the adhesive layer, the buffer layer and the functional layer on the long rod aluminum alloy. The cooling mechanism cools the adhesive layer, the buffer layer and the functional layer to obtain the plastic-coated metal profile. The thickness of the adhesive layer is 0.16 mm, the thickness of the buffer layer is 2.24 mm, and the thickness of the functional layer is 0.63 mm.

[0054] Example 3

[0055] Reference Figure 1 A method for preparing a plastic-coated metal profile using a co-extrusion molding system, the co-extrusion molding system including a traction mechanism, a heating mechanism, a mold assembly, a first co-extrusion machine, a second co-extrusion machine, a third co-extrusion machine and a cooling mechanism. The preparation method includes:

[0056] Maleic anhydride grafted polyethylene is used as the adhesive layer raw material, and the grafting rate of the maleic anhydride grafted polyethylene is 1.2%. First, bake at 80°C for 2 hours to remove moisture to reduce the swelling rate of the prepared adhesive layer. The adhesive layer raw material is put into the first co-extrusion machine and heated to melt into liquid state.

[0057] Recycled HDPE, recycled LDPE, first filler, lubricant and auxiliary agent are used as the buffer layer raw materials, which are put into the second co-extrusion machine and heated to melt into liquid state. The first filler is dispersed in the molten liquid in powder state. The mass percentage of each component of the buffer layer raw materials is: HDPE 60%, LDPE 10%, first filler 26%, lubricant 3% and auxiliary agent 1%. The auxiliary agent is hydrogenated styrene-butadiene block copolymer. The first filler includes 1 / 3 wood powder, 1 / 3 calcium powder and 1 / 3 talcum powder. The lubricant is fatty acid amide.

[0058] The functional layer raw materials of HDPE, second filler, adhesive, anti-aging agent and color masterbatch are put into the third co-extrusion machine and heated to melt into liquid state, and the second filler is dispersed in the molten liquid in powder state. The raw materials of the functional layer include the following components with mass fraction: HDPE 70%, second filler 17%, adhesive 3%, anti-aging agent 5%, and color masterbatch 5%. The second filler includes 1 / 3 wood powder, 1 / 3 calcium powder and 1 / 3 talc powder. The adhesive is polyacrylate. The anti-aging agent is benzotriazole.

[0059] The traction mechanism pushes the long rod aluminum alloy forward, and the heating mechanism preheats the long rod aluminum alloy during the pushing process. The long rod aluminum alloy enters the mold assembly, and the first co-extrusion machine, the second co-extrusion machine and the third co-extrusion machine successively coat the adhesive layer, the buffer layer and the functional layer on the long rod aluminum alloy. The cooling mechanism cools the adhesive layer, the buffer layer and the functional layer to obtain a plastic-wrapped metal profile. The thickness of the adhesive layer is 0.24 mm, the thickness of the buffer layer is 2.13 mm, and the thickness of the functional layer is 0.71 mm.

[0060] Comparative Example 1

[0061] Compared with Example 1, the buffer layer is cancelled in this comparative example, and a method for preparing a plastic-wrapped metal profile is as follows.

[0062] A method for preparing a plastic-wrapped metal profile uses a co-extrusion molding system to prepare the plastic-wrapped metal profile, and the co-extrusion molding system includes a traction mechanism, a heating mechanism, a mold assembly, a first co-extrusion machine, a second co-extrusion machine and a cooling mechanism. The preparation method includes:

[0063] Maleic anhydride grafted polyethylene is used as the adhesive layer raw material, and the grafting rate of the maleic anhydride grafted polyethylene is 1.0%. First, bake at 80°C for 2 hours to remove moisture to reduce the swelling rate of the prepared adhesive layer. The adhesive layer raw material is put into the first co-extrusion machine and heated to melt into liquid state.

[0064] HDPE, second filler, adhesive, anti-aging agent and color masterbatch are used as the functional layer raw materials, which are put into the second co-extrusion machine and heated to melt into liquid state, and the second filler is dispersed in the molten liquid in powder state. The raw materials of the functional layer include the following components with mass fraction: HDPE 81.6%, second filler 9.2%, adhesive 1.8%, anti-aging agent 3.7%, and color masterbatch 3.7%. The second filler includes 1 / 3 wood powder, 1 / 3 calcium powder and 1 / 3 talc powder. The adhesive is SBS. The anti-aging agent is benzophenone.

[0065] The traction mechanism pushes the long rod aluminum alloy forward, and in the process of pushing, the heating mechanism preheats the long rod aluminum alloy, the long rod aluminum alloy enters the mold assembly, and the first and second co-extrusion machines successively coat the bonding layer and the functional layer on the long rod aluminum alloy, and the cooling mechanism cools the bonding layer and the functional layer to obtain the plastic-coated metal profile. The thickness of the bonding layer is 0.20mm, and the thickness of the functional layer is 0.77mm.

[0066] Comparative Example 2

[0067] The present comparative example adopts a technical solution basically same as that of Example 1 to prepare a plastic-coated metal profile, the only difference being that the thickness of the bonding layer of the present comparative example is 0.10mm.

[0068] Comparative Example 3

[0069] The present comparative example adopts a technical solution basically same as that of Example 1 to prepare a plastic-coated metal profile, the only difference being that the thickness of the bonding layer of the present comparative example is 0.5mm.

[0070] Comparative Example 4

[0071] The present comparative example adopts a technical solution basically same as that of Example 1 to prepare a plastic-coated metal profile, and maleic anhydride grafted polyethylene is also used as the bonding layer raw material, the only difference being that the grafting rate of the maleic anhydride grafted polyethylene of the present comparative example is 2.5%.

[0072] Comparative Example 5

[0073] The present comparative example adopts a technical solution basically same as that of Example 1 to prepare a plastic-coated metal profile, the only difference being that the bonding layer raw material used in the present comparative example is thread glue.

[0074] Comparative Example 6

[0075] The present comparative example adopts a technical solution basically same as that of Example 1 to prepare a plastic-coated metal profile, the only difference being that the auxiliary agent used in the buffer layer raw material of the present comparative example is ethylene-propylene acid copolymer.

[0076] Test Example 1

[0077] The plastic-coated metal profiles prepared in Examples 1-3 and Comparative Examples 1-6 are tested as shown in Table 1 below.

[0078] Table 1 Performance test of plastic-coated metal profile

[0079]

[0080]

[0081]

[0082] In Table 1, the outdoor exposure, high-low temperature cycle, boiling water and peel strength tests are all performed on new materials that have not been tested.

[0083] The peel strength test in Table 1 is the initial peel strength of the test product without other tests. The peel strength of the test product without a buffer layer is the peel strength of the functional layer, and the peel strength of the rest is the peel strength of the integrated functional layer and buffer layer.

[0084] As can be seen from the results in Table 1, the plastic-coated metal profiles prepared in Examples 1-3 have good resistance to strong light, high-low temperature impact, boiling water, and large peel strength. Figure 2 The image of the test product of Example 1 after outdoor exposure shows that there is no obvious change at the outer end, no gel opening, 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 while maintaining effectiveness. Figure 3 The image of the test product of Example 2 after high-low temperature cycle testing shows 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 mainly occurs at the end of the test product, and the presence of metal core material exposure indicates that the buffer layer and the functional layer have significant shrinkage. The absence of end metal exposure indicates that the buffer layer and the functional layer have no significant shrinkage.

[0085] In contrast, the test product of Comparative Example 1 has no buffer layer, is prone to gel opening under strong light and high-low temperature impact conditions, has a short outdoor service life, and has a small peel strength, which makes it prone to gel opening and the functional layer prone to shrinkage, Figure 4 The test product of Comparative Example 1 after outdoor exposure testing has four sides that are gel opening, and the functional layer is easily peeled off by hand. Figure 5 The test product of Comparative Example 1 after high-low temperature testing has a functional layer shrinkage at the end position, and the metal core material is exposed when viewed from the side. Figure 6The end position of the test product of Comparative Example 1 showed shrinkage of the functional layer after the boiling test, and the metal core material was exposed in side view. The test product of Comparative Example 2 had a too small adhesive layer thickness, was prone to adhesive failure, and had a peel strength slightly smaller than that of the test product of Example 1-3. The test product of Comparative Example 3 had a too large adhesive layer thickness, which also led to the test product being prone to adhesive failure. The grafting rate of the maleic anhydride grafted polyethylene of Comparative Example 4 was too high at 2.5%, the melt of the adhesive layer ruptured, a continuous phase could not be formed, and the adhesive layer was prone to adhesive failure. The adhesive layer material used in the test product of Comparative Example 5 was thread sealant, which was prone to adhesive failure when applied to the plastic-coated metal profile of the present application, and the peel strength was small, indicating that the adhesion between the adhesive layer and the buffer layer was small. The buffer layer material of the test product of Comparative Example 6 used an additive of ethylene-acrylic acid copolymer, and after outdoor exposure and high-low temperature cycle tests, the buffer layer had slight cracking. This is because the ethylene-acrylic acid copolymer as an additive does not significantly improve the heat resistance and oxidation resistance of the buffer layer compared to hydrogenated styrene-butadiene block copolymer.

[0086] Test Example 2

[0087] Referring to the preparation method of Example 1, the buffer layer material and the functional layer material were prepared separately, and the hardness of the buffer layer material and the functional layer material was tested, as follows.

[0088] The buffer layer material was prepared by using recycled HDPE, recycled LDPE, first filler, lubricant, and additive as the buffer layer raw material, heating to melt into a liquid state, and dispersing the first filler in powder form in the molten liquid. The mass percentage of each component of the buffer layer raw material is: HDPE 50%, LDPE 20%, first filler 26%, lubricant 2%, and additive 2%. The additive is hydrogenated styrene-butadiene block copolymer. The first filler includes 1 / 3 wood powder, 1 / 3 calcium powder, and 1 / 3 talc powder. The lubricant is silicone oil.

[0089] The functional layer material was prepared by using HDPE, second filler, adhesive, anti-aging agent, and color master as the functional layer raw material, heating to melt into a liquid state, and dispersing the second filler in powder form in the molten liquid. The raw material of the functional layer includes the following mass fractions of components: HDPE 81.6%, second filler 9.2%, adhesive 1.8%, anti-aging agent 3.7%, and color master 3.7%. The second filler includes 1 / 3 wood powder, 1 / 3 calcium powder, and 1 / 3 talc powder. The adhesive is SBS. The anti-aging agent is benzophenone.

[0090] Hardness test: the Brinell hardness of the buffer layer was 54.2 MPa, and the Brinell hardness of the functional layer was 63.7 MPa. The Brinell hardness of the buffer layer was smaller than that of the functional layer.

[0091] In summary, the above examples and comparative examples, the example uses four layers of cladding structure, aluminum alloy as the base material layer, cladding a layer of adhesive layer, and then cladding a layer of buffer layer, the outermost cladding a layer of functional layer, compared with no buffer layer of plastic package aluminum profile, increase a layer of buffer layer, has the following advantages: from the extrusion process, is beneficial to the positioning of the profile, this is because the aluminum alloy of several meters in length, when the center position of the slight deviation, will lead to the outer cladding uneven thickness, even lack of material, buffer layer can cover the aluminum alloy in the length direction of the micro deviation and micro bending deformation, help to the centering of aluminum profile, reduce the functional layer thickness uneven, lack of material and other phenomena; if the defective products, can be treated by grinding and other ways to secondary use; significantly reduce the effect of thermal expansion and contraction on the adhesive layer, improve the effectiveness of the adhesion; the intermediate buffer layer can be prepared using a variety of recycled plastic, wood powder, etc., the thickness of the functional layer of high material cost can be designed to be relatively thin, thereby reducing the cost of products; improve the impact resistance of the product, can reduce the damage of collision, has better heat insulation function.

[0092] Aluminum alloy is chemically active and easy to be oxidized. The above examples coat the surface of the long rod aluminum alloy with an adhesive layer, a buffer layer and a functional layer, which protects the aluminum alloy. This not only improves the corrosion resistance of the profile, but also improves its heat resistance, and beautifies the surface of the profile, making the product more aesthetic and increasing its commercial value.

[0093] The above are only some embodiments of the present application, and the protection scope of the present application is not limited to the above examples. It should be noted that some improvements and refinements made by ordinary skilled persons in the technical field without departing from the creative design of the present application should also fall within the protection scope 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 bonded together from the inside out; the adhesive layer covers the metal core material; the buffer layer covers the adhesive layer; and the functional layer covers the buffer layer. The buffer layer and the functional layer are joined together by thermal fusion. The buffer layer is made of plastic; the functional layer is made of plastic; the hardness of the buffer layer is less than that of the functional layer; The buffer layer and the functional layer are polymers with the same composition; each polymer accounts for 30% to 100% of the mass of the buffer layer and the functional layer. The polymer in the buffer layer is recycled material; 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 is less than or equal to the mass percentage of HDPE in the functional layer. The raw material of the buffer layer includes the following components by mass fraction: HDPE 40~60%, LDPE 10~30%, first filler 20~30%, lubricant 1~3%, and additives 1~3%; the additives are hydrogenated styrene-butadiene block copolymers. The raw materials of the functional layer include the following components by mass fraction: HDPE 70~90%, second filler 5~20%, adhesive 1~3%, anti-aging agent 2~5%, and color masterbatch 2~5%; The adhesive layer is made of maleic anhydride-grafted polyethylene, with a grafting rate of 0.8-1.2% and a thickness of 0.15-0.25 mm.

2. The plastic-coated metal profile according to claim 1, characterized in that, The first filler includes wood flour, calcium powder and talc.

3. A method for preparing a plastic-coated metal profile as described in claim 1 or 2, characterized in that, The plastic-coated metal profile is prepared using a co-extrusion molding system, the co-extrusion molding system comprising 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: Maleic anhydride-grafted polyethylene is used as the adhesive layer material and is placed in the first co-extruder and heated to melt. Recycled HDPE, recycled LDPE, first filler, lubricant and additives are used as buffer layer raw materials and put into the second co-extruder for heating and melting. HDPE, second filler, adhesive, anti-aging agent and color masterbatch are used as functional layer raw materials, and are put into the third co-extruder and heated to melt. The traction mechanism propels the metal core forward. During the propulsion process, the heating mechanism preheats the metal core. The metal core enters the mold assembly, where the first co-extruder, the second co-extruder, and the third co-extruder sequentially coat the metal core 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.

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