Multilayer material for recycling SMC (Sheet Molding Compound), preparation mold and preparation method

Abstract

The embodiment of the invention discloses an SMC recycled multi-layer material, a preparation mold and a preparation method.The SMC recycled multi-layer material comprises an SMC semi-finished product and a foaming material layer, the SMC semi-finished product comprises a top plate and a surrounding edge arranged around the outer edge of the top plate, a cavity is formed by the top plate and the surrounding edge, and the foaming material layer is arranged in the cavity. The cavity is filled with the foaming material layer, and the interior of the foaming material layer is evenly filled with crushed SMC recycled materials. According to the multi-layer material for recycling the SMC, the mechanical performance of the multi-layer material is guaranteed, and meanwhile efficient recycling of the waste SMC is achieved. The filling of the foaming material layer reduces the density, improves the sound insulation characteristic, optimizes the processing adaptability, reduces the production cost, and has the advantages of environmental protection and economy.

Description

Technical Field

[0001] The present invention relates to the technical field of SMC (Sheet Molding Compound) sheet molding compound, and more specifically, to a multi-layer material for SMC recycling, a preparation mold, and a preparation method thereof. Background Art

[0002] SMC (Sheet Molding Compound) is a high-strength and high-rigidity composite material, which is widely used in fields such as automobiles, aerospace, and construction. However, SMC materials are mainly composed of unsaturated polyester resins, glass fibers, and fillers, and their thermosetting characteristics make it difficult to melt and reshape after curing, restricting the feasibility of traditional mechanical recycling or chemical recycling methods. Currently, the treatment of scrapped SMC components mainly relies on incineration or landfill, but these methods have certain environmental problems: incineration may release harmful gases such as styrene monomer or dioxin, while landfill may cause long-term environmental pollution. In addition, due to the relatively large density of SMC materials, they occupy more landfill space, which also increases the cost of waste management. Summary of the Invention

[0003] The present invention aims to solve one of the technical problems in the related art to a certain extent. For this purpose, an embodiment of the present invention provides a multi-layer material for SMC recycling. While ensuring mechanical properties, the multi-layer material realizes the efficient recycling of waste SMC. The filling of the foaming material layer reduces the density, improves the sound insulation characteristics, optimizes the processing adaptability, and at the same time reduces the production cost, having environmental and economic advantages.

[0004] An embodiment of the present invention also provides a mold for preparing the above-mentioned multi-layer material for SMC recycling.

[0005] An embodiment of the present invention also provides a method for preparing the above-mentioned multi-layer material for SMC recycling.

[0006] The technical solution adopted by the present invention is as follows: A multi-layer material for SMC recycling is provided, which includes an SMC semi-finished product and a foaming material layer. The SMC semi-finished product includes a top plate and a surrounding edge provided around the outer edge of the top plate. A cavity is formed between the top plate and the surrounding edge. The foaming material layer is filled in the cavity, and the inside of the foaming material layer is evenly filled with crushed SMC recycled materials.

[0007] After adopting the above structure, the multi-layer material can effectively recycle waste SMC materials while ensuring mechanical properties. Specifically, the filling of the foamed material layer not only reduces the density of the overall material, making it lighter, but also improves the sound insulation characteristics of the material. Since the crushed SMC recycled material is evenly dispersed in the foamed material, this recycled material can partially replace the virgin foaming foam material, thereby reducing production costs and improving resource utilization. In addition, this structure can maintain good processing adaptability without affecting the overall strength and durability of the material, making it applicable to the molding of products with different shapes and sizes. Compared with traditional landfill and incineration treatment methods, the technical solution of the present invention has obvious advantages in terms of environmental friendliness and economic feasibility, providing a new idea for the sustainable development of SMC materials.

[0008] According to an embodiment of the present invention, the SMC recycled material is particles with a particle size range of 0.1 mm - 20 mm, preferably particles with a particle size range of 2 mm - 5 mm.

[0009] According to an embodiment of the present invention, the mass ratio of the SMC recycled material to the foam material in the foamed material layer is 5:100 to 80:20, preferably the mass ratio is 20:80 to 30:70.

[0010] According to an embodiment of the present invention, the foam material includes at least one of the following: foamed polyethylene, foamed polypropylene, foamed polystyrene, foamed ethylene-vinyl acetate, and foamed polyurethane.

[0011] A preparation mold for a multi-layer material includes an SMC molding mold and a foaming molding mold. The SMC molding mold is used to prepare an SMC semi-finished product, and the foaming molding mold is used to fill the cavity of the SMC semi-finished product with a foam material containing the SMC recycled material and cool and form a foamed material layer.

[0012] According to an embodiment of the present invention, when the upper mold core of the foaming molding mold is closed, it contacts the peripheral edge of the SMC semi-finished product to seal the cavity of the SMC semi-finished product.

[0013] According to an embodiment of the present invention, the foaming molding mold includes a first foaming mold and a second foaming mold. The first foaming mold is used to foam and form a first foamed material layer in the cavity of the SMC semi-finished product, and the second foaming mold is used to form a second foamed material layer on the surface of the first foamed material layer.

[0014] According to an embodiment of the present invention, the combination of the first foamed material layer and the second foamed material layer constitutes the foamed material layer.

[0015] A preparation method for a multi-layer material such as SMC recycling and reuse includes the following steps: S1. Prepare SMC semi-finished products using an SMC molding die; S2. Place the SMC semi-finished products into a first foaming die, and fill and form a first foaming material layer in its cavity.

[0016] A method for preparing a multi-layer material by recycling SMC is characterized by comprising the following steps: S1. Prepare SMC semi-finished products using an SMC molding die; S2. Place the SMC semi-finished products into a first foaming die, and fill and form a first foaming material layer in its cavity; S3. Place the SMC semi-finished products containing the first foaming material layer into a second foaming die, and form a second foaming material layer on the surface of the first foaming material layer. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a cross-sectional view of the SMC die in the embodiment of the present invention.

[0019] Figure 2 It is a cross-sectional view of the SMC semi-finished product in the embodiment of the present invention.

[0020] Figure 3 It is a cross-sectional view of the first foaming die in the embodiment of the present invention.

[0021] Figure 4 It is a cross-sectional view of the multi-layer material in the embodiment of the present invention.

[0022] Figure 5 It is a schematic structural diagram of the first foaming die in the embodiment of the present invention.

[0023] Figure 6 It is a schematic structural diagram of the second foaming die in the embodiment of the present invention.

[0024] Explanation of the reference numerals in the drawings: 10. SMC die; 20. Multi-layer material; 30. First foaming die; 40. Second foaming die; 21. SMC semi-finished product; 22. First foaming material layer; 23. Second foaming material layer; 21a. Top plate; 21b. Perimeter; 21c. Cavity. Detailed Embodiments

[0025] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having like or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0026] In this embodiment, the SMC filler is made by crushing waste SMC materials, and its composition is as follows: Component Content (wt%) SMC debris (particle size 2 mm - 5 mm) 70-90 Calcium carbonate 5-15 Glass fiber (chopped fiber, length 3 - 6 mm) 5-15 The SMC filler is subjected to screening, cleaning, and drying treatments to ensure good dispersibility when filled into the foamed material layer and to form a firm bond with the foamed material.

[0027] The SMC semi-finished product is formed by sheet molding compound, and its main components are as follows: Component Content (wt%) Unsaturated polyester resin 20-35 Glass fiber (chopped fiber, length 25 - 50 mm) 25-40 Calcium carbonate filler 15-30 Initiator (peroxide) 1-3 Toughening agent (styrene monomer or vinyl monomer) 3-7 Other additives (demolding agent, diluent, etc.) 1-5 The SMC semi-finished product is formed by compression molding to form a shell-like structure with a top plate and a surrounding edge, providing a closed cavity for subsequent filling of the foamed material layer.

[0028] The foamed material layer is composed of a polymer foaming system and SMC filler, and the formula is as follows: Component Content (wt%) Polyurethane or expanded polyethylene 50-80 SMC filler (broken SMC particles) 10-40 Foaming agent (such as AC foaming agent) 1-5 Crosslinking agent 0.5-2 Stabilizer 0.5-2 In some other embodiments, the foam material is one or more of foamed polypropylene, foamed polystyrene, foamed ethylene-vinyl acetate, and foamed polyurethane.

[0029] Examples 1 to 2 As Figures 1 - 4 shown, in this embodiment, a multi-layer material for SMC recycling and reuse is disclosed, including an SMC semi-finished product and a foamed material layer. The SMC semi-finished product includes a top plate and a surrounding edge disposed around the outer edge of the top plate. The top plate and the surrounding edge form a cavity, and the foamed material layer is filled in the cavity, and the crushed SMC recycled material is uniformly filled inside the foamed material layer.

[0030] In this embodiment, a preparation mold for the multi-layer material is also disclosed, including an SMC molding mold and a foaming molding mold. The SMC molding mold is used to prepare the SMC semi-finished product, and the foaming molding mold is used to fill the foamed material containing the SMC recycled material into the cavity of the SMC semi-finished product and cool and form it into a foamed material layer. When the upper mold core of the foaming molding mold is closed, it contacts the edge of the surrounding edge of the SMC semi-finished product to seal the cavity of the SMC semi-finished product. The foaming molding mold includes a foaming mold, which is used to foam and form a foamed material layer in the cavity of the SMC semi-finished product.

[0031] In this embodiment, the preparation method of the mold includes the following steps: S1. Use an SMC molding die to prepare an SMC semi-finished product. The SMC is ordinary SMC sheet molding compound, with a width of 1000 mm - 1500 mm and a thickness of 2 mm. That is, place the SMC sheet into the SMC molding die. The SMC molding die is pre-heated to 120°C - 160°C to promote the resin curing reaction. At the same time, coat the mold surface with a release agent to prevent the formed product from adhering. Then place the pre-cut SMC sheet into the mold cavity according to the set weight and shape, ensuring uniform material distribution to guarantee the structural integrity of the formed product. Close the upper and lower molds of the SMC mold and apply high pressure (usually 5 - 15 MPa). Under the action of high temperature and high pressure, the resin gradually flows to fill the cavity, and at the same time, a cross-linking curing reaction occurs. The glass fiber plays a reinforcing role during the molding process, enabling the formed SMC semi-finished product to have good mechanical properties. After curing for a certain period of time (generally 30 - 300 seconds, depending on the material formula, and curing for 120 seconds in this embodiment), the SMC semi-finished product reaches the designed strength and dimensional stability, and then cools down to the demolding temperature; S2. Place the SMC semi-finished product into a foaming mold and fill and form a foaming material layer in its cavity; that is, place the shell-shaped SMC semi-finished product into the foaming mold. The opening of the SMC semi-finished product faces the injection end of the foaming mold. When the upper mold of the foaming mold is closed, the upper mold core contacts the peripheral edge of the SMC semi-finished product to seal the cavity of the SMC semi-finished product. Then the foaming mold injects a foaming material into this cavity. The foaming material is mixed with SMC recycled material. The foaming agent decomposes by heat or undergoes a chemical reaction to generate gas, prompting the material to expand in volume and form a uniform porous structure. As the reaction progresses, the foaming material gradually fills the entire mold cavity and completes curing within a certain period of time, finally obtaining a foamed product with stable dimensions and uniform density. Among them, the mass ratio of the SMC recycled material to the foam material in the foaming material layer is 5:100.

[0032] The difference between the second embodiment and the first embodiment is that in the second embodiment, the mass ratio of the SMC recycled material to the foam material in the foaming material layer is 80:20.

[0033] Embodiments Three to Eight Combined with Figures 5 - 6 As shown, the difference between this embodiment and the first embodiment is that in the first embodiment, the foaming material layer adopts a single-layer structure, while in this embodiment, the foaming material layer adopts a double-layer structure.

[0034] In this embodiment, a preparation mold for multi-layer materials is also disclosed, which includes an SMC molding mold and a foaming molding mold. The SMC molding mold is used to prepare SMC semi-finished products, and the foaming molding mold is used to fill a cavity of the SMC semi-finished product with a foam material containing SMC recycled material and cool and form a foaming material layer. When the upper mold core of the foaming molding mold is closed, it contacts the peripheral edge of the SMC semi-finished product to seal the cavity of the SMC semi-finished product. The foaming molding mold includes a first foaming mold and a second foaming mold. The first foaming mold is used to foam and form a first foaming material layer in the cavity of the SMC semi-finished product, and the second foaming mold is used to form a second foaming material layer on the surface of the first foaming material layer. The combination of the first foaming material layer and the second foaming material layer constitutes the foaming material layer.

[0035] In this embodiment, the preparation method of the mold includes the following steps: S1. Use the SMC molding mold to prepare SMC semi-finished products. The SMC is ordinary SMC sheet molding compound with a size of 1000 mm - 1500 mm in width and 2 mm in thickness. That is, place the SMC sheet into the SMC molding mold, and the SMC molding mold is pre-heated to 120°C - 160°C to promote the resin curing reaction. At the same time, apply a mold release agent to the mold surface to prevent the molded product from adhering. Then place the pre-cut SMC sheet into the mold cavity according to the set weight and shape to ensure uniform material distribution and guarantee the structural integrity of the molded product. The upper and lower molds of the SMC mold are closed, and a high pressure (usually 5 - 15 MPa) is applied. Under the action of high temperature and high pressure, the resin gradually flows to fill the cavity, and at the same time, a cross-linking curing reaction occurs. The glass fiber plays a reinforcing role during the molding process, enabling the molded SMC semi-finished product to have good mechanical properties. After a certain curing time (generally 30 - 300 seconds, depending on the material formula, and cured for 120 seconds in this embodiment), the SMC semi-finished product reaches the designed strength and dimensional stability, and then the temperature is lowered to the demolding temperature; S2. Place the SMC semi-finished product into the first foaming mold and fill and form a first foaming material layer in its cavity; that is, place the shell-shaped SMC semi-finished product into the first foaming mold, with the opening of the SMC semi-finished product facing the injection end of the first foaming mold. When the upper mold of the first foaming mold is closed, the upper mold core contacts the peripheral edge of the SMC semi-finished product to seal the cavity of the SMC semi-finished product. Then the first foaming mold injects a foaming material into the cavity. The foaming material is mixed with SMC recycled material. Under appropriate temperature and pressure, the foaming agent decomposes by heat or undergoes a chemical reaction to generate gas, prompting the material to expand in volume and form a uniform porous structure. As the reaction progresses, the foaming material gradually fills the entire mold cavity and completes curing within a certain time, finally obtaining a foaming product with stable dimensions and uniform density.

[0036] S3. Place the SMC semi-finished product in the second foaming mold, and fill and form a second foaming material layer in its cavity; that is, place the shell-shaped SMC semi-finished product into the second foaming mold, with the opening of the SMC semi-finished product facing the injection end of the second foaming mold. When the upper mold of the second foaming mold is closed, the upper mold core contacts the peripheral edge of the SMC semi-finished product to seal the cavity of the SMC semi-finished product. Then, the second foaming mold injects foaming material into this cavity. The foaming material is mixed with SMC recycled material. The foaming agent decomposes by heat or undergoes a chemical reaction to generate gas, prompting the material to expand in volume and form a uniform porous structure. As the reaction progresses, the foaming material gradually fills the entire mold cavity and completes curing within a certain period of time, finally obtaining a foamed product with stable dimensions and uniform density.

[0037] Among them, the mass ratio of SMC recycled material to foam material in the foaming material layer is: First foaming material layer Second foaming material layer Example 3 5:100 80:20 Example 4 30:100 80:20 Example 5 50:100 60:20 Example 6 80:20 5:100 Example 7 80:20 30:100 Example 8 60:20 50:100 As can be seen from the above table, in Examples 3 to 5, the mass proportion of SMC recycled material in the second foaming material layer is greater than that in the first foaming material layer. In Examples 6 to 8, the mass proportion of SMC recycled material in the first foaming material layer is greater than that in the second foaming material layer. In this embodiment, the multi-layer material with SMC recycled and reused is used for outdoor weather-resistant floors, and the application scenarios include parks, garden bridges, etc. The thickness of the multi-layer material is 20 - 100 mm. Therefore, the multi-layer material with SMC recycled and reused is used as the test group, and the sound insulation test is carried out according to Standard ASTM E2179 - 09. The test results are shown in the following table: Test item Thickness (mm) Improvement amount of walking noise (%) Improvement amount of impact noise (%) Example 1 48 23 12 Example 2 48 28 17 Example 3 48 24 13 Example 4 48 26 15 Example 5 48 26 16 Example 6 48 30 21 Example 7 48 32 24 Example 8 48 29 23 As can be seen from the above test results, under different mass ratios of SMC recycled material to foam material, there are certain differences in the improvement effects of the multi-layer material with SMC recycled and reused on walking noise and impact noise. Among them, the improvement amount of walking noise in Example 7 is the highest, reaching 32%, while the improvement amount of impact noise in Example 6 is the highest, being 21%.

[0038] Further analysis of the test results shows that the mass ratio of SMC recycled material in the first foaming material layer and the second foaming material layer has a significant impact on the sound insulation performance of the final product. When the mass proportion of SMC recycled material in the first foaming material layer is relatively high (such as in Examples 6 and 7), the improvement effect of impact noise is better, presumably related to the strengthening effect of SMC recycled material and the structural characteristics of the foaming material. When the mass proportion of SMC recycled material in the second foaming material layer is relatively high (such as in Examples 2 and 5), the improvement effect of walking noise is relatively better, which may be because the second foaming material layer is closer to the surface layer and has a stronger ability to absorb high-frequency noise. The final product in Example 8 has the best comprehensive sound insulation performance and can significantly improve impact noise and walking noise.

[0039] In addition, from the overall trend, appropriately increasing the proportion of SMC recycled material can improve the noise suppression effect, but too high a content of SMC recycled material may affect the uniformity and mechanical properties of the foamed material layer. Therefore, in specific applications, it is necessary to adjust the proportion of SMC recycled material in the first foamed material layer and the second foamed material layer according to actual needs to achieve the optimal noise suppression performance.

[0040] In summary, the present invention provides a multi-layer material based on SMC recycled material, which not only effectively recycles SMC waste and realizes resource reuse, but also exhibits excellent sound insulation performance in the application of outdoor weather-resistant floors. By adjusting the proportion of SMC recycled material in the first foamed material layer and the second foamed material layer, the sound insulation effect in different application scenarios can be optimized.

[0041] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0042] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0043] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A multi-layer material for SMC recycling and reuse, characterized in that: It includes an SMC semi-finished product and a foaming material layer. The SMC semi-finished product includes a top plate and a surrounding edge provided around the outer edge of the top plate. The top plate and the surrounding edge form a cavity, the foaming material layer is filled in the cavity, and the broken SMC recycled material is evenly filled inside the foaming material layer.

2. The multi-layer material for SMC recycling according to claim 1, characterized in that: The SMC recycled material is particles with a particle size range of 0.1 mm - 20 mm.

3. The multi-layer material for SMC recycling according to claim 1, wherein: The mass ratio of the SMC recycled material to the foam material in the foaming material layer is 5:100 to 80:

20.

4. The multi-layer material for SMC recycling according to claim 3, characterized in that: The foam material includes at least one of the following: expanded polyethylene, expanded polypropylene, expanded polystyrene, ethylene-vinyl acetate foam, and polyurethane foam.

5. A preparation mold for a multi-layer material as described in any one of claims 1-4, characterized in that: It includes an SMC molding die and a foaming molding die. The SMC molding die is used to prepare the SMC semi-finished product, and the foaming molding die is used to fill the cavity of the SMC semi-finished product with the foam material containing the SMC recycled material and cool and form it into a foaming material layer.

6. The manufacturing die for the multi-layer material according to claim 5, characterized in that: When the upper mold core of the foaming molding die is closed, it contacts the edge of the surrounding edge of the SMC semi-finished product to seal the cavity of the SMC semi-finished product.

7. The preparation mold for the multi-layer material according to claim 5, characterized in that: The foaming molding die includes a first foaming die and a second foaming die. The first foaming die is used to foam and form a first foaming material layer in the cavity of the SMC semi-finished product, and the second foaming die is used to form a second foaming material layer on the surface of the first foaming material layer.

8. The preparation mold for the multi-layer material according to claim 7, characterized in that: The combination of the first foaming material layer and the second foaming material layer constitutes the foaming material layer.

9. A method for preparing a multi-layer material for SMC recycling as described in any one of claims 1-4, characterized in that It includes the following steps: S1. Prepare the SMC semi-finished product using the SMC molding die; S2. Place the SMC semi-finished product in the first foaming die and fill and form the first foaming material layer in its cavity.

10. A method for preparing a multi-layer material for SMC recycling as described in any one of claims 1-4, characterized in that It includes the following steps: S1. Prepare the SMC semi-finished product using the SMC molding die; S2. Place the SMC semi-finished product in the first foaming die and fill and form the first foaming material layer in its cavity; S3. Place the SMC semi-finished product containing the first foaming material layer into the second foaming die and form the second foaming material layer on the surface of the first foaming material layer.

Images