Composite material plate as well as preparation method and application thereof

Abstract

The invention relates to a composite material plate and a preparation method and application thereof, the structure and processing technology of a multilayer metal plate composite material are designed aiming at the problems that a bending technology metal cabinet product is prone to sinking in the using process, by introducing a honeycomb aluminum material, the problem that a plate face is prone to sinking can be solved, and the strength of the plate is improved; in addition, the composite material plate structure further has the advantages of water resistance and moisture resistance, the problems caused by water swelling can be solved, and the service life of a product is prolonged. In addition, by directly adopting a cutting and edge sealing process on the composite material plate, the processing efficiency can be remarkably improved, the cost for preparing the bathroom cabinet body is reduced, and the product competitiveness is high.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material preparation, and in particular to a composite material plate and a preparation method and application thereof. Background Art

[0002] With the improvement of people's living standards, bathroom cabinets are more and more widely used. Bathroom cabinets are usually made of solid wood, PVC, density board, metal plate, etc. Among them, bathroom cabinets made of some materials will absorb water and swell during use due to being in a humid environment. In severe cases, the edge banding will fall off, making it unusable, seriously affecting the user experience and shortening the product life.

[0003] Metal bathroom cabinets have gradually become a popular choice because of their good waterproof, moisture-proof and corrosion-resistant properties. Most of the metal bathroom cabinets on the market are currently produced by bending technology. For example, CN102989869A discloses a bathroom cabinet and its manufacturing process, wherein the bathroom cabinet includes a stainless steel frame, side walls and cabinet doors. The side walls and cabinet doors are composed of a panel and a side panel. The panel has a first bending portion, a second bending portion and a third bending portion, and forms a cavity. The side panel has a fourth bending portion, and the fourth bending portion is inserted into the cavity. The manufacturing process is: cutting, punching, bending, wood grain processing, stainless steel frame production, installation, etc. However, the processing steps of this product are relatively cumbersome and the production efficiency is low.

[0004] In addition, some bathroom cabinets use internal and external buckle plate technology, and the corners are connected with plastic parts, which requires high product processing accuracy. If the requirements are not met, there will be problems such as large gaps and corner depressions. The internal and external buckle metal cabinets also have fatal shortcomings, such as poor impact resistance. When they are subjected to external force during transportation or use, pits are prone to appear, which cannot be repaired.

[0005] CN102613926A discloses a metal bathroom cabinet, including supporting feet, side panels, door panels, back panels and bottom panels made of metal substrates, wherein the side panels or door panels are provided with shaping plates or shaping strips to produce various shapes of surfaces, and the shapes of the shaping plates or shaping strips match the surface shapes of the side panels or door panels. A method for making a metal bathroom cabinet is also disclosed. The side panels and the front panel are shaped by using shaping plates or shaping strips, and the supporting feet are bent or processed by other methods and the skirt is cut, so that the metal bathroom cabinet produces a variety of surface shapes with beautiful lines. The processing efficiency of the bathroom cabinet prepared by the invention is low, the cost is high, and the large-scale production of the product has limitations.

[0006] Therefore, in view of the shortcomings of the prior art, it is necessary to provide a composite material board that can be used in bathrooms, has strong structural impact resistance and low production cost. Summary of the invention

[0007] The object of the present invention is to provide a composite material board and a preparation method and application thereof. The composite material board has a strong structural impact resistance and a low production cost and can meet the requirements for being used as a bathroom cabinet material.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a composite material plate, comprising a coating layer, an aluminum substrate layer, a honeycomb aluminum layer, an aluminum substrate layer and a coating layer stacked in sequence; the honeycomb aluminum layer is arranged in a hexagonal honeycomb hole shape, and the single side length of the hexagonal honeycomb hole is 3-5mm.

[0010] The composite material board provided by the present invention has a honeycomb aluminum material pressed between two layers of aluminum substrate layers, and at the same time limits the single-side length of the hexagonal honeycomb holes of the honeycomb aluminum layer to a reasonable range, which can significantly improve the strength of the board and avoid the problem of dents during use; by coating the surface of the aluminum substrate, the waterproof and moisture-proof properties of the board can be improved and the service life can be extended.

[0011] The length of a single side of the hexagonal honeycomb hole is 3-5 mm, for example, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0012] The structure of the honeycomb aluminum layer adopts a regular hexagon, and its main advantages are high specific strength, high specific stiffness, and light weight, which helps to improve the mechanical properties of the product.

[0013] Preferably, the thickness of the aluminum substrate layer is 0.3-1.2 mm, for example, 0.3 mm, 0.5 mm, 0.7 mm, 0.8 mm or 1.2 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 0.5-0.8 mm.

[0014] Preferably, the wall thickness of the hexagonal honeycomb cells is 0.36-0.4 mm, for example, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm or 0.4 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0015] Preferably, an adhesive layer is provided between the coating layer and the aluminum substrate layer, and between the aluminum substrate layer and the aluminum honeycomb panel layer, respectively.

[0016] Preferably, the material of the adhesive layer includes polyurethane AB glue.

[0017] Preferably, the material of the coating layer includes PET film or PVC film.

[0018] In a second aspect, the present invention provides a method for preparing the composite material plate as described in the first aspect, the preparation method comprising the following steps:

[0019] Placing the honeycomb aluminum material between the first bonding surfaces of the two aluminum substrates for lamination; then laminating the second bonding surfaces of the two aluminum substrates to obtain the composite material plate;

[0020] Alternatively, the first bonding surfaces of the two aluminum substrates are subjected to a coating treatment; and then the honeycomb aluminum material is placed between the second bonding surfaces of the two aluminum substrates for a pressing treatment to obtain the composite material plate.

[0021] The preparation method of the composite material plate provided by the present invention designs a processing technology for a multi-layer metal plate composite material in view of the problem that a bending process metal cabinet product is prone to dents during use. By introducing honeycomb aluminum material, the problem of the plate surface being prone to dents can be solved, thereby improving the strength of the plate. In addition, the composite material plate structure has the advantages of being waterproof and moisture-proof through lamination treatment, effectively solving the problem caused by water absorption and expansion, and extending the service life of the product.

[0022] Preferably, before the lamination process and the coating process, adhesive is coated on the first bonding surface and the second bonding surface of the two aluminum substrates respectively.

[0023] Preferably, the coating amount of the adhesive is 74.5-120 g / m 2 , for example, it can be 74.5g / m 2 , 89g / m 2 , 92g / m 2 , 95g / m 2 , 100g / m 2 , 105g / m 2 or 120g / m 2 , but not limited to the listed values, other values ​​not listed in the numerical range are also applicable, preferably 95-105g / m 2 .

[0024] Preferably, the amount of the honeycomb aluminum material is 0.74-1.05 kg / m 2 , for example, it can be 0.745kg / m 2 , 0.835kg / m 2 , 0.895kg / m 2 , 0.955kg / m 2 or 1.05kg / m 2 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the pressure of the pressing treatment is 2500-4000 MPa, for example, 2500 MPa, 3000 MPa, 3500 MPa, 3800 MPa or 4000 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 3500 MPa.

[0026] Preferably, the holding time of the pressing treatment is 6-10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 8 hours.

[0027] Preferably, the lamination pressure of the coating treatment is 2500-4000 MPa, for example, 2500 MPa, 3000 MPa, 3500 MPa, 3800 MPa or 4000 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 3500 MPa.

[0028] Preferably, the holding time of the coating treatment is 6-10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 8 hours.

[0029] Preferably, the coating treatment temperature is 150-180°C, for example, 150°C, 160°C, 170°C, 175°C or 180°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 170°C.

[0030] Preferably, the production speed of the production line of the composite material board is 19-25m / min, for example, it can be 19m / min, 20m / min, 22m / min, 23m / min or 25m / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] In a third aspect, the present invention provides an application of the composite material board as described in the first aspect, wherein the composite material board is used to prepare a bathroom cabinet, and the method for preparing the bathroom cabinet comprises the following steps:

[0032] (a) cutting the composite material plate to a target size, and then performing edge banding treatment with edge banding strips to obtain a finished composite material plate;

[0033] (b) punching and assembling the finished composite material board obtained in step (a) to obtain the bathroom cabinet.

[0034] The composite material board is suitable for preparing bathroom cabinet bodies. On the one hand, it has high-strength structure and waterproof and moisture-proof characteristics. On the other hand, by directly adopting the cutting and edge sealing process for the composite material board, the processing efficiency can be significantly improved, the cost can be reduced, and the product competitiveness is higher than other bathroom cabinets.

[0035] Preferably, the material of the edge banding strip in step (a) includes PVC or ABS.

[0036] Preferably, the drilling in step (b) is performed using a six-sided drill.

[0037] Preferably, the assembly in step (b) is performed by using rivet connectors.

[0038] The composite material panels are processed to obtain bottom panels, side panels, tie bars, visor panels and door panels that meet target dimensions, and then connected by rivet connectors to complete assembly.

[0039] Preferably, a circular plastic stopper is placed in the door hinge hole used for the assembly in step (b).

[0040] The main function of the circular plastic stopper is to reduce the noise generated by the direct contact between the door hinge and the honeycomb aluminum material, and effectively prevent the debris of the honeycomb aluminum material from falling off.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The composite material plate provided by the present invention aims at the problem that bending process metal cabinet products are prone to dents during use, and designs the structure and processing technology of the multi-layer metal plate composite material. By introducing honeycomb aluminum material and limiting the single-side length of the hexagonal honeycomb holes of the honeycomb aluminum layer within a reasonable range, the problem that the plate surface is prone to dents can be solved, and the strength of the plate can be improved. In addition, the composite material plate structure also has the advantages of being waterproof and moisture-proof, completely solving the problems caused by water absorption and expansion, and extending the service life of the product. In addition, by directly adopting the cutting and edge sealing process for the composite material plate, the processing efficiency can be significantly improved, the cost of preparing the bathroom cabinet body can be reduced, and the product competitiveness is strong. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] Example 1

[0045] The present embodiment provides a composite material plate, which includes a PVC film layer, an aluminum substrate layer, a honeycomb aluminum layer, an aluminum substrate layer and a PVC film layer stacked in sequence; a polyurethane AB glue layer is respectively arranged between the PVC film layer and the aluminum substrate layer, and between the aluminum substrate layer and the aluminum honeycomb plate layer.

[0046] The thickness of the aluminum substrate layer is 0.7 mm; the honeycomb aluminum layer is stacked in the form of hexagonal honeycomb holes, the single side length of the hexagonal honeycomb holes is 3 mm, and the wall thickness is 0.38 mm.

[0047] The method for preparing the composite material plate comprises the following steps:

[0048] Polyurethane AB glue is applied on the first bonding surface of the two aluminum substrates, with a coating amount of 100g / m 2 , then 0.895kg / m 2 The honeycomb aluminum material is placed between two aluminum substrates for pressing, the pressure is 3000MPa, and the pressure holding time is 8h; the second bonding surfaces of the two aluminum substrates are coated with polyurethane AB glue, and the coating amount is 100g / m 2 ; Then, a PVC film is used for lamination treatment, the pressing pressure is 3000MPa, the holding time is 8h, the temperature is 170°C, and the composite material board is obtained. The production speed of the production line where the composite material board is located is 22m / min.

[0049] The composite material board is used to prepare a bathroom cabinet, and the method for preparing the bathroom cabinet comprises the following steps:

[0050] (a) cutting the composite material board to a target size, and then using a PVC edge banding strip to perform edge banding to obtain a finished composite material board;

[0051] (b) using a six-sided drill to punch holes in the finished composite material board obtained in step (a), and then using rivet connectors to connect the bottom plate, side plates, pull strips, fascia and door panels made of the composite material board, and placing circular plastic baffles in the door hinge holes, and completing the assembly to obtain the bathroom cabinet body.

[0052] Example 2

[0053] The present embodiment provides a composite material plate, which includes a PET film layer, an aluminum substrate layer, a honeycomb aluminum layer, an aluminum substrate layer and a PET film layer stacked in sequence; a polyurethane AB glue layer is respectively arranged between the PET film layer and the aluminum substrate layer, and between the aluminum substrate layer and the aluminum honeycomb plate layer.

[0054] The thickness of the aluminum substrate layer is 0.5 mm; the honeycomb aluminum layer is stacked in the form of hexagonal honeycomb holes, the single side length of the hexagonal honeycomb holes is 5 mm, and the wall thickness is 0.36 mm.

[0055] The method for preparing the composite material plate comprises the following steps:

[0056] Polyurethane AB glue is applied on the first bonding surfaces of the two aluminum substrates, with a coating amount of 95g / m 2 , then 0.74kg / m 2 The honeycomb aluminum material is placed between two aluminum substrates for pressing, the pressure is 2500MPa, and the pressure holding time is 10h; the second bonding surfaces of the two aluminum substrates are coated with polyurethane AB glue, and the coating amount is 95g / m 2 ; Then, a PET film is used for lamination treatment, the pressing pressure is 2500MPa, the holding time is 10h, the temperature is 150°C, and the composite material board is obtained. The production speed of the production line where the composite material board is located is 25m / min.

[0057] The composite material board is used to prepare a bathroom cabinet, and the method for preparing the bathroom cabinet comprises the following steps:

[0058] (a) cutting the composite material board to a target size, and then using a PVC edge banding strip to perform edge banding to obtain a finished composite material board;

[0059] (b) using a six-sided drill to punch holes in the finished composite material board obtained in step (a), and then using rivet connectors to connect the bottom plate, side plates, pull strips, fascia and door panels made of the composite material board, and placing circular plastic baffles in the door hinge holes, and completing the assembly to obtain the bathroom cabinet body.

[0060] Example 3

[0061] The present embodiment provides a composite material plate, which includes a PVC film layer, an aluminum substrate layer, a honeycomb aluminum layer, an aluminum substrate layer and a PVC film layer stacked in sequence; a polyurethane AB glue layer is respectively arranged between the PVC film layer and the aluminum substrate layer, and between the aluminum substrate layer and the aluminum honeycomb plate layer.

[0062] The thickness of the aluminum substrate layer is 0.8 mm; the honeycomb aluminum layer is stacked in the form of hexagonal honeycomb holes, the single side length of the hexagonal honeycomb holes is 4 mm, and the wall thickness is 0.4 mm.

[0063] The method for preparing the composite material plate comprises the following steps:

[0064] Polyurethane AB glue was applied on the first bonding surfaces of the two aluminum substrates, with a coating amount of 105 g / m 2 Then, PVC film was used for lamination treatment, with a pressing pressure of 4000MPa, a holding time of 6h, and a temperature of 180°C; polyurethane AB glue was applied to the second bonding surfaces of the two aluminum substrates, with a coating amount of 105g / m2 , then 1.05kg / m 2 The honeycomb aluminum material is placed between two aluminum substrates for pressing at a pressure of 4000 MPa and a holding time of 6 hours to obtain the composite material plate. The production speed of the production line of the composite material plate is 19 m / min.

[0065] The composite material board is used to prepare a bathroom cabinet, and the method for preparing the bathroom cabinet comprises the following steps:

[0066] (a) cutting the composite material board to a target size, and then using a PVC edge banding strip to perform edge banding to obtain a finished composite material board;

[0067] (b) using a six-sided drill to punch holes in the finished composite material board obtained in step (a), and then using rivet connectors to connect the bottom plate, side plates, pull strips, fascia and door panels made of the composite material board, and placing circular plastic baffles in the door hinge holes, and completing the assembly to obtain the bathroom cabinet body.

[0068] Example 4

[0069] This embodiment provides a composite material plate, which is different from the embodiment 1 in that the thickness of the aluminum substrate is adjusted to 0.3 mm, and the coating amount of the polyurethane AB glue in the preparation method of the composite material plate is adjusted to 74.5 g / m 2 , the rest are the same as in Example 1.

[0070] Example 5

[0071] This embodiment provides a composite material plate, which is different from the embodiment 1 in that the thickness of the aluminum substrate is adjusted to 1.2 mm, and the coating amount of the polyurethane AB glue in the preparation method of the composite material plate is adjusted to 120 g / m 2 , the rest are the same as in Example 1.

[0072] Example 6

[0073] This embodiment provides a composite material plate. The difference between the preparation method of the composite material plate and that of Embodiment 1 is that, except that the pressure of the pressing treatment is adjusted to 2000MPa and the pressing pressure of the coating treatment is adjusted to 2000MPa, the rest is the same as that of Embodiment 1.

[0074] Example 7

[0075] This embodiment provides a composite material plate. The difference between the preparation method of the composite material plate and that of Embodiment 1 is that, except that the pressure of the pressing treatment is adjusted to 4500 MPa and the pressing pressure of the coating treatment is adjusted to 4500 MPa, the rest is the same as that of Embodiment 1.

[0076] Comparative Example 1

[0077] This comparative example provides a bathroom cabinet, which adopts the bathroom cabinet disclosed in CN102989869A.

[0078] Comparative Example 2

[0079] This comparative example provides a composite material plate, which is different from Example 1 in that, except that the single side length of the hexagonal honeycomb holes of the honeycomb aluminum material is adjusted to 2.5 mm, the rest is the same as Example 1.

[0080] Comparative Example 3

[0081] This comparative example provides a composite material plate, which is different from Example 1 in that, except that the single side length of the hexagonal honeycomb holes of the honeycomb aluminum material is adjusted to 5.5 mm, the rest is the same as Example 1.

[0082] The bathroom cabinet bodies made of the composite material panels provided in Examples 1-7, Comparative Examples 2 and 3, and the bathroom cabinet provided in Comparative Example 1 were subjected to a mechanical property-ultimate strength test using GB 24977 bathroom furniture, and the results obtained were divided into "no damage", "slightly loose", and "loose"; a drop test was carried out using the GBT 4857.5-1992 packaging and transport package drop test method, and the results obtained were divided into "intact", "slightly damaged", "damaged", and "severely damaged"; the screw holding force was tested using the GB-T 17657-2022 test method for physical and chemical properties of artificial boards and veneered artificial boards, and the results obtained are shown in Table 1.

[0083] Table 1

[0084] Mechanical properties-ultimate strength Drop test Screw holding force (N) Example 1 No damage Intact 786 Example 2 No damage Intact 652 Example 3 No damage Slightly damaged 734 Example 4 Slightly loose Slightly damaged 423 Example 5 No damage Intact 740 Example 6 Loose Lossy 427 Example 7 Loose Lossy 431 Comparative Example 1 Loose Seriously damaged 409 Comparative Example 2 Loose Seriously damaged 421 Comparative Example 3 Loose Seriously damaged 415

[0085] It can be seen from Table 1 that the bathroom cabinet body made of the composite material board provided by the present invention has excellent strength and screw holding force, and can meet the requirements of the bathroom environment;

[0086] By comparing Example 1 with Examples 6 and 7, it can be seen that if the pressing pressure is too small, the composite material plate structure will be easily unstable, thereby affecting the strength and screw holding force. If the pressure is too large, the internal honeycomb aluminum structure will be destroyed, thereby reducing the strength and screw holding force.

[0087] By comparing Example 1 with Comparative Example 1, it can be seen that the strength of the bathroom cabinet produced by the metal bending process is significantly reduced, serious dents will occur during use, and the production efficiency will be reduced; by comparing Example 1 with Comparative Examples 2 and 3, it can be seen that the single-side length of the hexagonal honeycomb holes of the honeycomb aluminum material exceeds the specified range, which will reduce the strength and screw holding force of the product, and further cause dents during use.

[0088] To sum up, the composite material plate provided by the present invention is designed to solve the problem that the metal cabinet products produced by the bending process are prone to dents during use, and the structure and processing technology of the multi-layer metal plate composite material are designed. By introducing honeycomb aluminum material and limiting the single-side length of the hexagonal honeycomb holes of the honeycomb aluminum layer to a reasonable range, the problem that the plate surface is prone to dents can be solved, and the strength of the plate can be improved. In addition, the composite material plate structure also has the advantages of being waterproof and moisture-proof, which can solve the problems caused by water absorption and expansion, and extend the service life of the product. In addition, by directly adopting the cutting and edge sealing process for the composite material plate, the processing efficiency can be significantly improved, the cost of preparing bathroom cabinets can be reduced, and the product competitiveness is strong.

[0089] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A composite material board, characterized in that: The composite material plate comprises a coating layer, an aluminum substrate layer, a honeycomb aluminum layer, an aluminum substrate layer and a coating layer which are stacked in sequence; the honeycomb aluminum layer is arranged in a hexagonal honeycomb hole shape, and the single side length of the hexagonal honeycomb hole is 3-5 mm.

2. The composite material plate according to claim 1, characterized in that: The thickness of the aluminum substrate layer is 0.3-1.2 mm, preferably 0.5-0.8 mm; Preferably, the wall thickness of the hexagonal honeycomb holes is 0.36-0.4 mm.

3. The composite material plate according to claim 1 or 2, characterized in that: An adhesive layer is provided between the coating layer and the aluminum substrate layer, and between the aluminum substrate layer and the aluminum honeycomb panel layer; Preferably, the material of the bonding layer includes polyurethane AB glue; Preferably, the material of the coating layer includes PET film or PVC film.

4. A method for preparing a composite material plate according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: Placing the honeycomb aluminum material between the first bonding surfaces of the two aluminum substrates for lamination; then laminating the second bonding surfaces of the two aluminum substrates to obtain the composite material plate; Alternatively, the first bonding surfaces of the two aluminum substrates are subjected to a coating treatment; and then the honeycomb aluminum material is placed between the second bonding surfaces of the two aluminum substrates for a pressing treatment to obtain the composite material plate.

5. The preparation method according to claim 4, characterized in that: Before the lamination process and the coating process, the first bonding surface and the second bonding surface of the two aluminum substrates are respectively coated with adhesive; Preferably, the coating amount of the adhesive is 74.5-120 g / m 2 , preferably 95-105g / m 2 ; Preferably, the amount of the honeycomb aluminum material is 0.74-1.05 kg / m 2 .

6. The preparation method according to claim 4 or 5, characterized in that: The pressure of the pressing treatment is 2500-4000MPa; Preferably, the holding time of the pressing process is 6-10 hours.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The lamination pressure of the lamination treatment is 2500-4000MPa; Preferably, the holding time of the coating treatment is 6-10 hours; Preferably, the coating treatment temperature is 150-180°C.

8. The preparation method according to any one of claims 4 to 7, characterized in that: The production speed of the production line of the composite material plate is 19-25 m / min.

9. An application of the composite material board according to any one of claims 1 to 3, characterized in that: The composite material board is used to prepare a bathroom cabinet, and the method for preparing a bathroom cabinet comprises the following steps: (a) cutting the composite material plate to a target size, and then performing edge banding treatment with edge banding strips to obtain a finished composite material plate; (b) punching and assembling the finished composite material board obtained in step (a) to obtain the bathroom cabinet.

10. The use according to claim 9, characterized in that: The material of the edge banding strip in step (a) includes PVC or ABS; Preferably, the assembly in step (b) is performed by using rivet connectors; Preferably, a circular plastic stopper is placed in the door hinge hole used for the assembly in step (b).