Method for preparing liner layer and helmet

Abstract

The present application relates to the technical field of helmets, and in particular to a method for preparing a cushioning layer and a helmet, the preparation method comprising: using expandable polystyrene to prepare closed-cell polystyrene in a granular state to obtain foam particles; using polystyrene cushion waste to prepare block-shaped open-cell polystyrene to obtain a block; the absolute value deviation between the density of the block and the density of the closed-cell polystyrene is no more than 5 g / L, and the hardness of the block is lower than the hardness of the closed-cell polystyrene; pasting a plurality of the blocks into the inner wall of a helmet die; combining a helmet punch and a helmet die to form a mold cavity, injecting the foam particles into the mold cavity and heating the mold cavity at a temperature of 102°C-110°C so that the foam particles adhere to each other and wrap all the blocks; and demolding after cooling and molding. The production cost can be reduced, and the cushioning capacity and impact resistance of the cushioning layer can be ensured while avoiding excessive weight of the cushioning layer.

Description

Technical Field

[0001] The present application relates to the technical field of helmets, and in particular to a method for preparing a liner layer and a helmet. Background Art

[0002] Since polystyrene itself is relatively inexpensive and has excellent performance, the lining layers of existing protective helmets are mainly made of polystyrene. However, during the production process, some polystyrene waste or unqualified lining layer scrap products are generated (these polystyrene waste and lining layer scrap products are collectively referred to as polystyrene lining waste). Usually, these polystyrene lining wastes need to be sent to recycling companies for harmless treatment, which will cause a waste of resources for the company. Since these polystyrene lining wastes contain foaming components, they need to be heated multiple times during the helmet production process, which will cause these foaming components to basically disappear, and thus cannot be directly used in product production. Therefore, the recycling and reuse of polystyrene lining waste is difficult, resulting in the existing lining layers can only be produced using new polystyrene materials, which cannot reduce production costs.

[0003] Furthermore, due to manufacturing processes and cost control considerations, helmet liners typically utilize a single padding structure (made solely of closed-cell polystyrene). Higher liner hardness improves impact resistance, but reduces cushioning capacity. Conversely, lower liner hardness increases cushioning capacity but reduces impact resistance; achieving a balance between these two is not possible. To achieve a balance between cushioning and impact resistance, a small number of helmets utilize a dual-layer or multi-layer padding structure. The layer directly connected to the helmet shell is a high-hardness closed-cell polystyrene layer, while the layer in contact with the user's head is a lower-hardness closed-cell polystyrene layer. While the higher-hardness closed-cell polystyrene layer ensures impact resistance, the lower-hardness closed-cell polystyrene layer provides cushioning. However, this significantly increases the thickness of the padding layer, leading to increased weight and bulk. Therefore, how to ensure both cushioning and impact resistance while minimizing the weight of the padding layer remains a pressing issue.

[0004] There is currently no effective technical solution to the above problems. Summary of the Invention

[0005] The purpose of this application is to provide a method for preparing a liner layer and a helmet, which can reduce production costs, ensure the cushioning capacity and impact resistance of the liner layer and avoid excessive weight of the liner layer.

[0006] In a first aspect, the present application provides a method for preparing a liner layer, comprising the following steps:

[0007] A1. Prepare closed-cell polystyrene particles using expandable polystyrene to obtain foam particles.

[0008] A2. A block of open-cell polystyrene is prepared using waste polystyrene liner to obtain a block; the absolute value of the deviation between the density of the block and the density of the closed-cell polystyrene is no more than 5 g / L, and the hardness of the block is lower than the hardness of the closed-cell polystyrene;

[0009] A3. The plurality of blocks are pasted on the inner wall of the helmet mold;

[0010] A4. Clamping the helmet male mold and the helmet female mold to form a mold cavity, injecting the foam particles into the mold cavity and heating at a temperature of 102°C-110°C so that the foam particles adhere to each other and wrap all the blocks;

[0011] A5. After cooling and molding, demould.

[0012] The preparation method of the cushioning layer provided in the present application can reduce the production cost of the cushioning layer by preparing block-shaped open-cell polystyrene from polystyrene cushioning waste. A plurality of blocks are pasted into the inner wall of the helmet die, the helmet convex mold and the helmet die are combined to form a mold cavity, and foam particles are injected into the mold cavity. The mold cavity is heated at a temperature of 102°C-110°C so that the foam particles adhere to each other and wrap all the blocks, thereby forming a cushioning layer. The relatively high hardness of the closed-cell polystyrene can ensure the impact resistance of the cushioning layer. When the closed-cell polystyrene is hit by the user's head, the closed-cell polystyrene will squeeze the blocks wrapped by it from all directions. Since the hardness of the block is relatively small, it can form a buffering effect on the extrusion force of the closed-cell polystyrene, thereby ensuring the buffering capacity of the cushioning layer. Compared with the cushioning layer prepared from a single closed-cell polystyrene, the cushioning layer obtained by this preparation method of the present application has better buffering capacity and impact resistance. In fact, the fragility of open-cell polystyrene is related to its density. The higher the density, the higher the anti-crushing ability. However, if the density is too high, it will cause the weight of the cushioning layer to be too large. In the present application, since the density of the block is close to that of the closed-cell polystyrene, while ensuring that the block has sufficient anti-crushing ability, the weight of the cushioning layer can be avoided to be too large.

[0013] Optionally, step A1 includes:

[0014] The expandable polystyrene plastic is heated at a temperature of 90°C-100°C to a particle state and pre-foamed to obtain closed-cell polystyrene in a particle state.

[0015] Optionally, step A2 includes:

[0016] A201. The polystyrene liner waste is added to the crushing granulator to obtain open-cell polystyrene particles;

[0017] A202. After screening the open-cell polystyrene particles using a screening device, they are stored according to density classification to obtain a variety of alternative pellets of different densities;

[0018] A203. According to the density of the closed-cell polystyrene, at least one of the alternative granular materials is selected to be mixed with the closed-cell polystyrene to form the block.

[0019] The present application can improve the recycling rate of polystyrene liner waste by preparing blocks from polystyrene liner waste. The preparation process is relatively simple and can effectively reduce the production cost of the liner layer.

[0020] Optionally, step A203 includes:

[0021] comparing the density of each of the candidate pellets with the density of the closed-cell polystyrene;

[0022] If the density of all the candidate pellets is lower than that of the closed-cell polystyrene, the candidate pellet with the largest density is selected and mixed with the closed-cell polystyrene in a mass ratio of 4:1;

[0023] If the density of all the candidate pellets is greater than that of the closed-cell polystyrene, the candidate pellet with the smallest density is selected and mixed with the closed-cell polystyrene in a mass ratio of 4:1;

[0024] If at least one of the alternative pellets has a density greater than that of the closed-cell polystyrene, and at least one of the alternative pellets has a density less than that of the closed-cell polystyrene, then an alternative pellet with a density greater than that of the closed-cell polystyrene and an alternative pellet with a density less than that of the closed-cell polystyrene are selected to be mixed with the closed-cell polystyrene so that the mass ratio of the alternative pellets to the closed-cell polystyrene is 4:1.

[0025] Optionally, the density deviations of the same type of alternative granular materials are no more than 5 g / L.

[0026] In order to ensure that the absolute value deviation between the density of the block and the density of closed-cell polystyrene is no more than 5g / L, while ensuring that the block has sufficient anti-crushing ability, the weight of the lining layer can be avoided to be too heavy. Therefore, when preparing the block, it is necessary to ensure that the density deviation between the same alternative granular materials is no more than 5g / L.

[0027] Optionally, step A203 further includes:

[0028] The mixed material is molded and heated using a first molding die to obtain a rod;

[0029] The rod is cut into pieces to obtain the blocks.

[0030] Optionally, step A203 further includes:

[0031] The mixed material is molded and heated using a second molding die to obtain the block.

[0032] Optionally, step A3 includes:

[0033] The blocks are bonded to the inner wall of the helmet cavity in an array arrangement manner.

[0034] Optionally, before step A3, the method includes the following steps:

[0035] Pasting the outer shell pattern film of the helmet on the inner wall of the helmet concave mold; the outer shell pattern film is provided with a plurality of pasting point marks;

[0036] Step A3 includes:

[0037] Paste one of the blocks at each of the pasting point marks.

[0038] In a second aspect, the present application further provides a helmet comprising a shell, wherein a lining layer is provided on the inner side of the shell, and the lining layer is obtained by the above-mentioned method for preparing the lining layer.

[0039] As can be seen from the above, the present application provides a method for preparing a cushioning layer and a helmet, by using expandable polystyrene to prepare closed-cell polystyrene in a granular state to obtain foam particles; using polystyrene cushioning waste to prepare block-shaped open-cell polystyrene to obtain blocks; the absolute value deviation between the density of the blocks and the density of the closed-cell polystyrene is no more than 5g / L, and the hardness of the blocks is lower than the hardness of the closed-cell polystyrene; a plurality of the blocks are pasted into the inner wall of a helmet die; a helmet punch and a helmet die are combined to form a mold cavity, the foam particles are injected into the mold cavity and heated at a temperature of 102°C-110°C to make the foam particles adhere to each other and wrap all the blocks; after cooling and molding, demolding is performed to form a cushioning layer, which can reduce production costs, ensure the cushioning capacity and impact resistance of the cushioning layer and avoid excessive weight of the cushioning layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic flow chart of a method for preparing a liner layer provided in this application.

[0041] Figure 2 This is a schematic structural diagram of the side of a cushion layer provided in this application.

[0042] Figure 3 Schematic diagram of the mold cavity structure of the method for preparing the liner layer provided in this application.

[0043] Figure 4 Comparative test data of the liner provided for this application and the comparative liner.

[0044] Explanation of reference numerals: 100, cushion layer; 200, block; 300, mold cavity. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work fall within the scope of protection of the present application.

[0046] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

[0047] Please refer to Figure 1 , Figure 1 It is a flow chart of a method for preparing a cushioning layer in an embodiment of the present application. The method for preparing the cushioning layer of the present application can reduce production costs, ensure the buffering capacity and impact resistance of the cushioning layer 100, and avoid excessive weight of the cushioning layer 100.

[0048] In a first aspect, the present application provides a method for preparing a liner, comprising the following steps:

[0049] A1. Prepare closed-cell polystyrene particles using expandable polystyrene to obtain foam particles.

[0050] A2. A block of open-cell polystyrene is prepared using waste polystyrene liner to obtain a block 200; the absolute value of the density of the block 200 and the density of the closed-cell polystyrene is not more than 5g / L, and the hardness of the block 200 is lower than that of the closed-cell polystyrene;

[0051] A3. The plurality of blocks 200 are pasted on the inner wall of the helmet mold;

[0052] A4. The helmet male mold and the helmet female mold are closed to form a mold cavity 300, the mold cavity 300 is injected with foam particles and heated at a temperature of 102 ℃ -110 ℃ so that the foam particles adhere to each other and wrap all the blocks 200;

[0053] A5. After cooling and molding, demould.

[0054] The density and hardness of closed-cell polystyrene refer to the density and hardness of closed-cell polystyrene at room temperature.

[0055] Specifically, if Figure 1 and Figure 3 As shown, by using polystyrene liner waste to prepare block-shaped open-cell polystyrene, the recycling rate of polystyrene liner waste can be improved, and the preparation method is relatively simple, thereby reducing the production cost of the liner layer 100. By pasting a plurality of blocks 200 on the inner wall of the helmet die, the helmet male mold and the helmet female mold are combined to form a mold cavity 300, and foam particles are injected into the mold cavity 300, and heated at a temperature of 102°C-110°C to make the foam particles adhere to each other and wrap all the blocks 200, thereby forming the liner layer 100. The relatively high hardness of the closed-cell polystyrene can ensure the impact resistance of the liner layer 100. When the closed-cell polystyrene is hit by the user's head, Closed-cell polystyrene will squeeze the blocks wrapped by it from all directions. Since the hardness of the blocks is relatively small, it can form a buffering effect on the squeezing force of the closed-cell polystyrene, thereby ensuring the buffering capacity of the liner layer. Compared with the liner layer prepared from a single closed-cell polystyrene, the liner layer obtained by this preparation method of the present application has better buffering capacity and impact resistance. In fact, the fragility of open-cell polystyrene is related to its density. The higher the density, the higher the anti-crushing ability. However, if the density is too high, it will cause the weight of the liner layer to be too large. In the present application, since the density of the blocks is close to that of the closed-cell polystyrene, while ensuring that the blocks have sufficient anti-crushing ability, the weight of the liner layer can be avoided to be too large.

[0056] The polystyrene liner waste includes polystyrene waste generated during the production process of the liner layer and / or discarded liner layer products.

[0057] In some embodiments, step A1 includes:

[0058] The expandable polystyrene plastic is heated at a temperature of 90°C-100°C to a particle state and pre-foamed to obtain closed-cell polystyrene in a particle state.

[0059] Specifically, the expandable beads in the expandable polystyrene plastic are expanded to different degrees. The density varies with the degree of expansion. The desired density of the closed-cell polystyrene is obtained by controlling the temperature and time. The density of the closed-cell polystyrene can be set according to actual needs and is not limited here.

[0060] In some embodiments, step A2 includes:

[0061] A201. The polystyrene liner waste is added to the crushing granulator to obtain open-cell polystyrene particles;

[0062] A202. After screening the open-cell polystyrene particles using a screening device, they are sorted and stored by density to obtain a variety of alternative pellets with different densities;

[0063] A203. Based on the density of the closed-cell polystyrene, select at least one alternative granular material to mix with the closed-cell polystyrene to form a block 200.

[0064] Specifically, by adding polystyrene liner waste to a crushing granulator, open-cell polystyrene particles can be directly obtained, thereby improving the recycling rate of polystyrene liner waste, and its preparation process is relatively simple, which can effectively reduce the production cost of the liner layer 100; since the fragility of open-cell polystyrene is related to its density, the greater the density, the higher the crushing resistance, but if the density is too high, the weight of the liner layer will be too large. Therefore, the open-cell polystyrene particles are density screened (since the polystyrene liner waste includes polystyrene waste generated during the production process of the liner layer, and / or scrapped liner products, the densities of polystyrene waste and scrapped liner products are not necessarily the same, resulting in different densities of the mixed open-cell polystyrene particles), classified and stored according to density, and a variety of alternative granules with different densities are obtained. At least one alternative granule with a density close to that of closed-cell polystyrene is selected so that the density of the block 200 prepared therefrom is close to the density of closed-cell polystyrene, while ensuring that the block 200 has sufficient crushing resistance, the weight of the liner layer 100 can be avoided from being too large.

[0065] In some embodiments, step A203 includes:

[0066] Compare the density of each candidate pellet with the density of closed-cell polystyrene;

[0067] If the density of all candidate granules is lower than that of closed-cell polystyrene, the candidate granules with the highest density are selected and mixed with closed-cell polystyrene in a mass ratio of 4:1;

[0068] If the density of all candidate granules is greater than that of closed-cell polystyrene, the candidate granules with the smallest density are selected and mixed with closed-cell polystyrene in a mass ratio of 4:1;

[0069] If at least one alternative pellet has a density greater than that of closed-cell polystyrene, and at least one alternative pellet has a density less than that of closed-cell polystyrene, then one alternative pellet with a density greater than that of closed-cell polystyrene and one alternative pellet with a density less than that of closed-cell polystyrene are selected to be mixed with the closed-cell polystyrene so that the mass ratio of the alternative pellets to the closed-cell polystyrene is 4:1.

[0070] Specifically, since the fragility of open-cell polystyrene is related to its density, the higher the density, the higher the crush resistance. However, if the density is too high, the weight of the cushioning layer will be too large. Therefore, the above-mentioned proportion control method is adopted according to the density of the alternative granular material and the density of the closed-cell polystyrene. The absolute value deviation between the density of the obtained block 200 and the density of the closed-cell polystyrene is not more than 5g / L. While ensuring that the block 200 has sufficient crush resistance, the weight of the cushioning layer 100 can be avoided from being too large. The better the impact resistance and buffering capacity of the cushioning layer 100, the higher its safety performance and the smaller its acceleration peak. According to the standard "GB811-2010", the cushioning layer 100 obtained in this application and the comparative cushioning layer were tested (the comparative cushioning layer refers to the cushioning layer made entirely of closed-cell polystyrene, and the thickness of the two cushioning layers is the same). The experimental data obtained are as follows Figure 4 As shown in the figure, the conditions corresponding to the general environment of the test environment are: 17℃~27℃, the conditions corresponding to the low temperature are: -17℃~-13℃, the conditions corresponding to the high temperature are: 47℃~53℃, and the conditions corresponding to water immersion are: complete immersion in water at a temperature of 17℃~27℃; among them, the definitions of acceleration peak and impact anvil can be found in the standard "GB811-2010", and the peak acceleration of the helmet standard does not exceed 300g. The peak acceleration of the liner layer 100 of the present application is smaller than the peak acceleration of the comparative liner layer, and the effect achieved is more advantageous. Therefore, the liner layer 100 of the present application can not only reduce the production cost, but also ensure the buffering capacity and impact resistance of the liner layer 100 and avoid the excessive weight of the liner layer 100.

[0071] In some embodiments, the density of the same candidate pellets may vary by no more than 5 g / L.

[0072] Specifically, in order to ensure that the absolute value deviation between the density of the block 200 and the density of closed-cell polystyrene is no more than 5 g / L, while ensuring that the block 200 has sufficient anti-crushing ability, the weight of the lining layer 100 can be avoided to be too large. Therefore, when preparing the block 200, it is necessary to ensure that the density deviation between the same alternative granular materials is no more than 5 g / L.

[0073] In some embodiments, step A203 further includes:

[0074] The mixed material (a mixture of block and foam particles) is molded and heated using a first molding die to obtain a rod;

[0075] The rod is cut into blocks 200 .

[0076] The cross-sectional shape of the rod can be set according to actual needs. In this embodiment, the cross-sectional shape of the rod is circular, which can ensure that when the cushion layer is impacted, the block 200 is compressed more evenly and has better buffering performance.

[0077] Specifically, the mixed material is first molded and heated by a first molding die to obtain a rod. When the rod is cut, the block 200 can be cut into a required length according to actual needs.

[0078] In some embodiments, step A203 further includes:

[0079] The mixed material is molded and heated using a second molding die to obtain a block 200.

[0080] Specifically, to facilitate obtaining the block 200, the mixed material can be directly molded and heated using the second molding die without additional cutting. For example, the second molding die includes multiple molding cavities, each with the same shape and dimensions as the desired block 200. Through molding and heating, a block 200 is formed in each molding cavity.

[0081] In some embodiments, step A3 includes:

[0082] The blocks 200 are bonded to the inner wall of the helmet mold in an array arrangement.

[0083] Specifically, in order to ensure that the lining layer 100 has both impact resistance and buffering capability, the blocks 200 are bonded to the inner wall of the helmet die in an array arrangement.

[0084] In some embodiments, before step A3, the method includes the following steps:

[0085] The outer shell pattern film of the helmet is pasted on the inner wall of the helmet cavity mold; a plurality of pasting point marks are set on the outer shell pattern film;

[0086] Step A3 includes:

[0087] A block 200 is pasted at each pasting point mark.

[0088] Specifically, in order to better combine the shell pattern film of the helmet with the liner layer 100, the shell pattern film of the helmet is pasted on the inner wall of the helmet mold, and in order to facilitate the pasting of the block 200, a plurality of pasting point marks are set on the shell pattern film.

[0089] Second, please refer to Figure 2 The present application also provides a helmet, comprising a shell, wherein a lining layer 100 is provided on the inner side of the shell, and the lining layer 100 is obtained by the above-mentioned lining layer preparation method.

[0090] Specifically, by providing the lining layer 100 in the helmet shell, the production cost can be reduced, the cushioning capacity and impact resistance of the lining layer 100 can be ensured, and the excessive weight of the lining layer 100 can be avoided.

[0091] The preparation method of the cushioning layer provided in the present application comprises the following steps: preparing closed-cell polystyrene in a granular state from expandable polystyrene to obtain foam particles; preparing block-shaped open-cell polystyrene from polystyrene cushion waste to obtain blocks 200; the absolute value deviation between the density of the blocks 200 and the density of the closed-cell polystyrene is no more than 5 g / L, and the hardness of the blocks 200 is lower than that of the closed-cell polystyrene; pasting a plurality of blocks 200 on the inner wall of a helmet die; combining the helmet punch and the helmet die to form a cavity 300, injecting foam particles into the cavity 300 and heating the cavity 300 at a temperature of 102°C-110°C so that the foam particles adhere to each other and wrap all the blocks 200; and demolding is performed after cooling and molding; the production cost can be reduced, and the cushioning capacity and impact resistance of the cushioning layer 100 can be ensured while avoiding excessive weight of the cushioning layer 100.

[0092] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interface, the indirect coupling or communication connection of the device or unit can be electrical, mechanical or other forms.

[0093] In addition, the units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0094] Furthermore, the functional modules in each embodiment of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0095] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any actual relationship or order between these entities or operations.

[0096] The above are merely examples of the present application and are not intended to limit the scope of protection of the present application. Those skilled in the art will appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a liner, characterized in that: The following steps are involved: A1. Prepare closed-cell polystyrene particles using expandable polystyrene to obtain foam particles. A2. A block of open-cell polystyrene is prepared using waste polystyrene liner to obtain a block; the absolute value of the deviation between the density of the block and the density of the closed-cell polystyrene is no more than 5 g / L, and the hardness of the block is lower than the hardness of the closed-cell polystyrene; A3. The plurality of blocks are pasted on the inner wall of the helmet mold; Step A3 includes: The blocks are bonded to the inner wall of the helmet mold in an array arrangement; Before step A3, the steps include: Pasting the outer shell pattern film of the helmet on the inner wall of the helmet concave mold; the outer shell pattern film is provided with a plurality of pasting point marks; Step A3 includes: Pasting one of the blocks at each of the pasting point marks; A4. Clamping the helmet male mold and the helmet female mold to form a mold cavity, injecting the granular material into the mold cavity and heating it at a temperature of 102°C-110°C so that the foam particles adhere to each other and wrap all the blocks; A5. After cooling and molding, demould.

2. The method for preparing a liner layer according to claim 1, wherein: Step A1 includes: The expandable polystyrene plastic is heated at a temperature of 90°C-100°C to a particle state and pre-foamed to obtain closed-cell polystyrene in a particle state.

3. The method for preparing a liner layer according to claim 1, wherein: Step A2 includes: A201. The polystyrene liner waste is added to the crushing granulator to obtain open-cell polystyrene particles; A202. After screening the open-cell polystyrene particles using a screening device, they are stored according to density classification to obtain a variety of alternative pellets of different densities; A203. According to the density of the closed-cell polystyrene, at least one of the alternative granular materials is selected to be mixed with the closed-cell polystyrene to form the block.

4. The method for preparing a liner layer according to claim 3, wherein: Step A203 includes: comparing the density of each of the candidate pellets with the density of the closed-cell polystyrene; If the density of all the candidate pellets is lower than that of the closed-cell polystyrene, the candidate pellet with the largest density is selected and mixed with the closed-cell polystyrene in a mass ratio of 4:1; If the density of all the candidate pellets is greater than that of the closed-cell polystyrene, the candidate pellet with the smallest density is selected and mixed with the closed-cell polystyrene in a mass ratio of 4:1; If at least one of the alternative pellets has a density greater than that of the closed-cell polystyrene, and at least one of the alternative pellets has a density less than that of the closed-cell polystyrene, then an alternative pellet with a density greater than that of the closed-cell polystyrene and an alternative pellet with a density less than that of the closed-cell polystyrene are selected to be mixed with the closed-cell polystyrene so that the mass ratio of the alternative pellets to the closed-cell polystyrene is 4:

1.

5. The method for preparing the liner layer according to claim 3, wherein: The density deviations of the same type of alternative pellets are no more than 5 g / L.

6. The method for preparing a liner layer according to claim 4, wherein: Step A203 also includes: The mixed material is molded and heated using a first molding die to obtain a rod; The rod is cut into pieces to obtain the blocks.

7. The method for preparing a liner layer according to claim 4, wherein: Step A203 also includes: The mixed material is molded and heated using a second molding die to obtain the block.

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