Multilayer tough paperboard

Abstract

The multi-layer tough paperboard provided by the embodiment of the utility model comprises a yellow paperboard layer and a connecting layer, the yellow paper board layer comprises a first layer of paper board and a second layer of paper board; the connecting layer comprises a supporting part and a bonding part; the bonding part covers and is connected to the surface of the supporting part; the connecting layer is arranged between the first layer of paperboard and the second layer of paperboard; and the bonding parts are respectively bonded with the first-layer paperboard and the second-layer paperboard, so that the undesirable phenomenon that scraps are generated due to the fact that burrs are easily broken when a traditional paperboard is folded or bent is solved to a certain extent, and the purpose of wide application of the paperboard is achieved.

Description

Technical Field

[0001] This utility model relates to the field of paperboard production technology, and in particular to a multi-layer strong and tough paperboard. Background Technology

[0002] Traditional cardboard, also known as corrugated cardboard, is mostly made from recycled waste paper through processes such as shredding, cooking, bleaching, and pulping. Due to its toughness and excellent tear resistance, it is often used to make packaging boxes, paper bags, and sound insulation materials. However, because of its relatively rough texture, poor flexibility, and susceptibility to breakage, corrugated cardboard may have some drawbacks in use. For example, its strength is relatively low, making it prone to tearing under significant pressure; moreover, its water resistance is poor, easily affected by humid environments, which can degrade its quality. Furthermore, in some applications, single-layer corrugated cardboard may not meet the requirements, as its special raw materials and processing techniques can cause it to break during folding, resulting in rough edges and debris that affect the product's appearance and usability.

[0003] Therefore, traditional cardboard is prone to breakage when folded or bent, resulting in rough edges and debris. Utility Model Content

[0004] In view of the above problems, the present invention aims to propose a multi-layer strong and tough cardboard, which fixes and bonds the cardboard layers by means of a connecting layer with an adhesive part, thereby solving to a certain extent the problem that traditional cardboard is prone to cracking and breaking when folded or bent, resulting in the generation of debris, and achieving the goal of widespread application of cardboard.

[0005] This utility model provides a multi-layer strong and tough paperboard, comprising: a yellow paperboard layer and a connecting layer; the yellow paperboard layer includes a first paperboard layer and a second paperboard layer; the connecting layer includes a support portion and an adhesive portion; the adhesive portion covers and connects to the surface of the support portion; the connecting layer is disposed between the first paperboard layer and the second paperboard layer; the adhesive portion is bonded to the first paperboard layer and the second paperboard layer respectively.

[0006] In this invention, the first layer of cardboard plays a crucial role in protecting and supporting the entire cardboard structure; the second layer provides a solid foundation for the overall structure; and the connecting layer, through lamination, tightly connects the first and second layers, forming a complete three-layer structure. This structure increases the mechanical properties of the cardboard during folding, avoiding problems such as breakage and burrs. Simultaneously, the connecting layer, bonded between adjacent cardboard layers, firmly secures the cardboard, effectively preventing delamination or loosening during normal use, thus maintaining the overall structural stability.

[0007] Furthermore, in the aforementioned multi-layered strong paperboard, the support portion has a mesh-like structure.

[0008] In this invention, the mesh structure can effectively improve the air permeability of the entire cardboard, allowing air to circulate more smoothly inside the cardboard and effectively avoiding adverse conditions such as dampness and odor that may be caused by poor air circulation.

[0009] Furthermore, in the aforementioned multi-layered strong cardboard, the supporting portion is a hollow regular hexagonal structure.

[0010] In this invention, the hexagonal structure is closer to a honeycomb structure, exhibiting higher structural strength and stability. This structure better disperses pressure, improving the cardboard's compressive strength. Simultaneously, at the same thickness, the hexagonal grid has a larger bonding area and higher bonding strength, thus enhancing the overall strength of the cardboard. Furthermore, compared to other grid shapes, the hexagonal grid has a larger opening area, allowing for smoother airflow and better breathability. This is particularly advantageous for items requiring breathable preservation, such as food and flowers.

[0011] Furthermore, in the aforementioned multi-layered strong cardboard, the support portion is made of a biodegradable material.

[0012] In this invention, the biodegradable support portion allows the cardboard to be decomposed by microorganisms in the natural environment after it has fulfilled its intended purpose and been discarded. Unlike materials that are difficult to degrade, it does not remain in the natural environment for extended periods, thus preventing pollution of soil, water, and other ecological elements, and promoting a green and environmentally friendly lifestyle. Furthermore, biodegradable materials are typically lightweight, adding minimal weight to the cardboard and facilitating transportation and handling. In addition, biodegradable materials can be composted with other organic waste to convert them into organic fertilizer, achieving resource recycling.

[0013] Furthermore, in the aforementioned multi-layered strong paperboard, the supporting portion is made of recycled fiber material.

[0014] In this invention, the support part is made of recycled fiber material, which has good biocompatibility and will not cause adverse reactions to the human body, making it suitable for the medical field; at the same time, recycled fiber has good air permeability and moisture absorption, which is beneficial for the application of cardboard; furthermore, recycled fiber is lightweight, making it more convenient to use.

[0015] Furthermore, in the aforementioned multi-layered strong paperboard, the adhesive portion is an adhesive; the connecting layer is a mesh fiber double-sided adhesive.

[0016] In this invention, the mesh fiber double-sided adhesive, with its mesh structure and the inherent properties of the fiber material, can significantly enhance the extensibility of cardboard, enabling it to better adapt to various bending and folding situations and greatly reducing the possibility of breakage or damage.

[0017] Furthermore, in the aforementioned multi-layered strong cardboard, the yellow cardboard layer is made of recyclable material.

[0018] In this invention, the recyclable cardboard layer facilitates the recycling of resources, which aligns perfectly with the current widespread demand for environmentally friendly materials.

[0019] Furthermore, in the aforementioned multi-layered strong paperboard, the yellow paperboard layer is made of recycled pulp.

[0020] In this invention, recycled pulp can be recycled and reused, reducing dependence on forest resources and reducing environmental pollution; at the same time, the cost of recycled pulp is usually lower than that of virgin pulp, which helps to reduce product costs.

[0021] Furthermore, in the aforementioned multi-layered strong paperboard, the yellow paperboard layer is provided with air vents penetrating the surface.

[0022] In this invention, air vents are provided that penetrate the surface, which makes the overall air permeability of the cardboard better and its application prospects wider.

[0023] Furthermore, in the aforementioned multi-layered strong paperboard, the air vents are round holes.

[0024] In this invention, the air vents with a circular hole structure are easy to implement and have a more aesthetically pleasing geometric appearance.

[0025] In summary, it can be seen that the multi-layer strong and tough cardboard provided by this utility model uses a connecting layer with an adhesive part to fix and bond the yellow cardboard layers, thereby achieving the purpose of widespread application of cardboard. This solves to a certain extent the problem that traditional yellow cardboard is prone to rough edge breakage and thus generates debris when folded or bent. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0027] Figure 1 This is a schematic diagram of the structure of the multi-layer strong and tough cardboard in Embodiment 1 of this utility model;

[0028] Figure 2 This is a partial cross-sectional view of the connecting layer in Embodiment 1 of this utility model;

[0029] Figure 3 This is a schematic diagram illustrating the application of the orthopedic splint in Embodiment 1 of this utility model;

[0030] Figure 4This is a schematic diagram of the structure of the multi-layer strong and tough cardboard in Embodiment 2 of this utility model; and

[0031] Figure 5 This is a schematic diagram of the overall packaging box in Embodiment 2 of this utility model.

[0032] Explanation of reference numerals in the attached figures

[0033] 10—Multi-layer strong cardboard; 101—Yellow cardboard layer; 1011—First layer cardboard; 1012—Second layer cardboard; 1013—Third layer cardboard; 102—Connecting layer; 1021—Supporting part; 1022—Adhesive part; 103—Ventilation hole; 20—Orthopedic splint; 30—Strap; 40—Upper limb; 50—Packaging box. Detailed Implementation

[0034] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the following is a detailed description of the embodiments of the multi-layer strong and tough cardboard of this utility model.

[0035] Example 1:

[0036] Reference Figures 1 to 3 This utility model provides an application of multi-layer strong and tough cardboard 10, namely, an orthopedic splint 20. The orthopedic splint 20 is composed of multiple multi-layer strong and tough cardboard 10s, and the shape of the multi-layer strong and tough cardboard 10s is cut according to the distribution and structural characteristics of human bones. In this embodiment, the orthopedic splint 20 for the upper limb 40 of the human body is taken as an example. The multi-layer strong and tough cardboard 10s are strips and there are three of them.

[0037] The aforementioned multi-layer strong paperboard 10 has three layers, including: a yellow paperboard layer 101 and a connecting layer 102; the yellow paperboard layer 101 includes a first paperboard layer 1011 and a second paperboard layer 1012; the connecting layer 102 includes a support portion 1021 and an adhesive portion 1022; the adhesive portion 1022 covers and connects to the surface of the support portion 1021; the connecting layer 102 is disposed between the first paperboard layer 1011 and the second paperboard layer 1012; the adhesive portion 1022 is bonded to the first paperboard layer 1011 and the second paperboard layer 1012 respectively.

[0038] In this invention, the first layer of cardboard 1011 plays a crucial role in protecting and supporting the entire cardboard structure; the second layer of cardboard 1012 provides a solid foundation for the overall structure; and the connecting layer 102 tightly connects the first layer of cardboard 1011 and the second layer of cardboard 1012 through bonding, forming a complete three-layer structure. This structure increases the mechanical properties of the cardboard when folded, avoiding problems such as breakage and burrs during folding; at the same time, the connecting layer 102, bonded between adjacent cardboard layers, can firmly fix the cardboard, effectively ensuring that the entire cardboard structure will not easily delaminate or loosen during normal use, thus effectively maintaining the overall stability of the multi-layer strong cardboard 10 structure.

[0039] Preferably, the first layer of cardboard 1011 has a flat surface.

[0040] Secondly, in the aforementioned multi-layer strong and tough paperboard 10, the support part 1021 has a grid-like structure.

[0041] In this invention, the mesh structure can effectively improve the air permeability of the entire multi-layer strong cardboard 10, allowing air to circulate more smoothly inside the cardboard and effectively avoiding adverse conditions such as dampness and odor that may be caused by poor air circulation.

[0042] Furthermore, in the aforementioned multi-layered strong cardboard 10, the support portion 1021 is a hollow regular hexagonal structure.

[0043] In this invention, the hexagonal structure is closer to a honeycomb structure, exhibiting higher structural strength and stability. This structure better disperses pressure, improving the cardboard's compressive strength. Simultaneously, at the same thickness, the hexagonal mesh has a larger bonding area and higher bonding strength, thus enhancing the overall strength of the cardboard. Furthermore, compared to other mesh shapes, the hexagonal mesh has a larger opening area, allowing for smoother airflow and better breathability. This is particularly beneficial for wound areas requiring ventilation.

[0044] Furthermore, in the aforementioned multi-layered strong cardboard 10, the support portion 1021 is made of a biodegradable material.

[0045] In this invention, the biodegradable support portion 1021, after the multi-layered, strong cardboard 10 has completed its intended function and is discarded, can be decomposed by microorganisms in the natural environment. Unlike materials that are difficult to degrade, it will not remain in the natural environment for a long time, thus polluting ecological elements such as soil and water, which is conducive to promoting a green and environmentally friendly lifestyle. At the same time, biodegradable materials are usually lightweight, which will not add too much weight to the cardboard, making it convenient for transportation and handling. In addition, biodegradable materials can be composted together with other organic waste to be converted into organic fertilizer, realizing resource recycling.

[0046] Furthermore, in the aforementioned multi-layer strong and tough paperboard 10, the support portion 1021 is made of recycled fiber material.

[0047] In this invention, the support part 1021 is made of recycled fiber material, which has good biocompatibility and will not cause adverse reactions to the human body, making it suitable for the medical field; at the same time, recycled fiber has good air permeability and moisture absorption, which is beneficial for the application of multi-layer strong and tough cardboard 10; furthermore, recycled fiber is lightweight, making it more convenient to use.

[0048] Furthermore, in the aforementioned multi-layer strong and tough paperboard 10, the adhesive portion 1022 is an adhesive; the connecting layer 102 is a double-sided mesh fiber adhesive.

[0049] In this invention, the double-sided adhesive of the mesh fiber, with its mesh structure and the characteristics of the fiber material itself, can significantly enhance the extensibility of the paperboard, enabling the multi-layer strong paperboard 10 to better adapt to various bending and folding situations, and greatly reducing the possibility of breakage or damage.

[0050] Furthermore, in the aforementioned multi-layer strong paperboard 10, the yellow paperboard layer 101 is a recyclable material.

[0051] In this invention, the recyclable cardboard layer 101 facilitates the recycling of resources, which aligns perfectly with the current widespread demand for environmentally friendly materials.

[0052] Furthermore, in the aforementioned multi-layer strong paperboard 10, the yellow paperboard layer 101 is made of recycled pulp.

[0053] In this invention, recycled pulp can be recycled and reused, reducing dependence on forest resources and reducing environmental pollution; at the same time, the cost of recycled pulp is usually lower than that of virgin pulp, which helps to reduce product costs.

[0054] Furthermore, in the aforementioned multi-layer strong paperboard 10, the yellow paperboard layer 101 is provided with ventilation holes 103 that penetrate the surface.

[0055] In this invention, a permeable vent 103 is provided through the surface, which makes the overall air permeability of the multi-layer strong and tough cardboard 10 better and its application prospects are more extensive.

[0056] Preferably, in the above-mentioned multi-layer strong and tough paperboard 10, the air vent 103 is a round hole.

[0057] In this invention, the vent 103 with a circular hole structure is easy to implement and has a more aesthetically pleasing geometric appearance.

[0058] Refer again Figures 1 to 3 In practical applications:

[0059] 1. Based on the specific injury location of the patient's upper limb 40, place three multi-layered strong cardboard 10 evenly;

[0060] 2. Secure the multi-layered strong cardboard 10 to the upper limb 40 of the human body using straps 30;

[0061] 3. With the help of the ventilation holes 103 and the mesh fibers, the extensibility of the paperboard can be significantly enhanced, allowing the multi-layer strong paperboard 10 to better adapt to various bending and folding situations, greatly reducing the possibility of the multi-layer strong paperboard 10 breaking or being damaged due to the movement of the upper limb 40; at the same time, although the multi-layer strong paperboard 10 is close to the upper limb 40, due to its good breathability, it will not produce adverse reactions such as dampness or odor.

[0062] 4. After the bone setting splint 20 is used up, it can be removed and classified as recyclable waste for easy reuse.

[0063] The application of multi-layer strong cardboard 10 in this embodiment, namely the orthopedic splint 20, can to some extent solve the problems of insufficient strength and easy breakage of traditional single-layer yellow cardboard as orthopedic splint, as well as the problems of poor air permeability and easy breakage when folding when the thickness of traditional yellow cardboard is increased.

[0064] Example 2:

[0065] Reference Figure 4 and Figure 5 This utility model embodiment also provides an application of the multi-layer strong and tough cardboard 10, namely a packaging box 50. The packaging box 50 is formed by assembling the multi-layer strong and tough cardboard 10 in a folded manner.

[0066] The aforementioned multi-layered strong cardboard 10 has five layers, including: a yellow cardboard layer 101 and a connecting layer 102; the yellow cardboard layer 101 includes a first cardboard layer 1011, a second cardboard layer 1012, and a third cardboard layer 1013; there are two connecting layers 102; each connecting layer 102 includes a support portion and an adhesive portion; the adhesive portion covers and connects to the surface of the support portion; a connecting layer 102 is provided between the first cardboard layer 1011 and the second cardboard layer 1012; a connecting layer 102 is provided between the second cardboard layer 1012 and the third cardboard layer 1013; the first cardboard layer 1011 and the second cardboard layer 1012 are bonded together by the adhesive portion; the second cardboard layer 1012 and the third cardboard layer 1013 are bonded together by the adhesive portion.

[0067] This invention comprises a five-layer structure consisting of three cardboard layers and two connecting layers 102. Compared to a three-layer structure, it offers better protection and support. Furthermore, the bonding of the two connecting layers 102 ensures overall stability, making it more suitable for transportation and packaging applications. It is also less prone to edge breakage or debris when folded or bent.

[0068] Secondly, in the aforementioned multi-layer strong and tough paperboard 10, the support part has a grid structure.

[0069] In this invention, the mesh structure can effectively improve the air permeability of the entire multi-layer strong cardboard 10, allowing air to circulate more smoothly inside the cardboard and effectively avoiding adverse conditions such as dampness and odor that may be caused by poor air circulation.

[0070] Furthermore, in the aforementioned multi-layer strong paperboard 10, the support portion is a hollow regular hexagonal structure.

[0071] In this invention, the hexagonal structure is closer to a honeycomb structure, exhibiting higher structural strength and stability. This structure better disperses pressure, improving the cardboard's compressive strength. Simultaneously, at the same thickness, the hexagonal mesh has a larger bonding area and higher bonding strength, thus enhancing the overall strength of the cardboard. Furthermore, compared to other mesh shapes, the hexagonal mesh has a larger opening area, allowing for smoother airflow and better breathability. This is particularly beneficial for wound areas requiring ventilation.

[0072] Furthermore, in the aforementioned multi-layered strong cardboard 10, the support portion is made of a biodegradable material.

[0073] In this invention, the biodegradable material supporting the multi-layered, strong cardboard 10, after fulfilling its intended purpose and being discarded, can be decomposed by microorganisms in the natural environment. Unlike materials that are difficult to degrade, it will not remain in the natural environment for a long time, thus avoiding pollution of ecological elements such as soil and water, and promoting a green and environmentally friendly lifestyle. At the same time, biodegradable materials are usually lightweight, not adding excessive weight to the cardboard, making transportation and handling convenient. Furthermore, biodegradable materials can be composted together with other organic waste to convert them into organic fertilizer, achieving resource recycling.

[0074] Furthermore, in the aforementioned multi-layer strong and tough paperboard 10, the support part is made of recycled fiber material.

[0075] In this invention, the support part is made of recycled fiber material, which has good air permeability and moisture absorption, which is beneficial to the application of multi-layer strong and tough cardboard 10; furthermore, recycled fiber is lighter in weight and more convenient to use.

[0076] Furthermore, in the aforementioned multi-layer strong paperboard 10, the adhesive part is an adhesive; the connecting layer 102 is a double-sided mesh fiber adhesive.

[0077] In this invention, the double-sided adhesive of the mesh fiber, with its mesh structure and the characteristics of the fiber material itself, can significantly enhance the extensibility of the paperboard, enabling the multi-layer strong paperboard 10 to better adapt to various bending and folding situations, and greatly reducing the possibility of breakage or damage.

[0078] Furthermore, in the aforementioned multi-layer strong paperboard 10, the yellow paperboard layer 101 is a recyclable material.

[0079] In this invention, the recyclable cardboard layer 101 facilitates the recycling of resources, which aligns perfectly with the current widespread demand for environmentally friendly materials.

[0080] Furthermore, in the aforementioned multi-layer strong paperboard 10, the yellow paperboard layer 101 is made of recycled pulp.

[0081] In this invention, recycled pulp can be recycled and reused, reducing dependence on forest resources and reducing environmental pollution; at the same time, the cost of recycled pulp is usually lower than that of virgin pulp, which helps to reduce product costs.

[0082] Furthermore, in the aforementioned multi-layer strong paperboard 10, the yellow paperboard layer 101 is provided with ventilation holes 103 that penetrate the surface.

[0083] In this invention, a permeable vent 103 is provided through the surface, which makes the overall air permeability of the multi-layer strong and tough cardboard 10 better and its application prospects are more extensive.

[0084] Preferably, in the above-mentioned multi-layer strong and tough paperboard 10, the air vent 103 is a round hole.

[0085] In this invention, the vent 103 with a circular hole structure is easy to implement and has a more aesthetically pleasing geometric appearance.

[0086] The application of multi-layer strong and tough cardboard 10 in this embodiment, namely packaging box 50, can solve the problems of rough edges and breakage after being squeezed or pulled by external forces to a certain extent. It has good air-permeable preservation function and can maintain its shape and structural integrity in handling, stacking and various complex usage environments, thereby properly ensuring the safety of the items inside the packaging.

[0087] It should be noted that in this utility model, the number of layers of the multi-layer strong and tough cardboard 10 is not limited to three or five layers. As long as the connecting layer 102 is located between the yellow cardboard layers 101 and is connected to each other by adhesive, it is acceptable to create a multi-layer strong and tough cardboard 10 that meets the needs of different application scenarios. Secondly, in addition to regular hexagons, other structures such as rectangles and circles can be selected for the grid structure, as long as they provide a breathable effect. Furthermore, the application of the multi-layer strong and tough cardboard 10 as an orthopedic splint is not limited to the forelimbs. According to the distribution and structural characteristics of human bones, it can be cut into other shapes, such as for fixing ankles and leg bones. Moreover, in addition to recycled pulp, the yellow cardboard layers 101 can also be made of natural fiber materials, as long as they are conducive to the recycling and reuse of cardboard.

[0088] In summary, this multi-layer strong and tough cardboard 10, as an environmentally friendly, lightweight, and biodegradable material, has broad application prospects in the medical and packaging transportation fields. Its excellent fixation performance, breathability, and extensibility make it an ideal choice for bone-setting treatment and wrapping. Simultaneously, its biodegradable properties align with the concept of green environmental protection, contributing to environmental conservation. By using the aforementioned multi-layer strong and tough cardboard 10, the problems of traditional yellow cardboard easily causing rough edges and breakage, resulting in debris, can be solved to a certain extent.

[0089] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0090] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly defined.

[0091] Numerous specific details are set forth in this specification. However, it will be understood that embodiments of this invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0092] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and description of this utility model.

Claims

1. A multi-layer strong and tough cardboard, characterized in that, include: Yellow cardboard layer and connecting layer; The yellow cardboard layer includes a first layer of cardboard and a second layer of cardboard; The connecting layer includes a support portion and an adhesive portion; The adhesive portion covers and connects to the surface of the support portion; The connecting layer is disposed between the first layer of paperboard and the second layer of paperboard; The adhesive portion is bonded to the first layer of cardboard and the second layer of cardboard, respectively.

2. The multi-layer strong and tough paperboard according to claim 1, characterized in that, The support part has a mesh structure.

3. The multi-layer strong and tough paperboard according to claim 2, characterized in that, The support portion is a hollow regular hexagonal structure.

4. The multi-layer strong and tough paperboard according to claim 1, characterized in that, The support is made of a biodegradable material.

5. The multi-layer strong and tough paperboard according to claim 4, characterized in that, The support is made of recycled fiber material.

6. The multi-layer strong and tough paperboard according to claim 5, characterized in that, The adhesive portion is made of adhesive; The connecting layer is a double-sided adhesive made of mesh fibers.

7. The multi-layer strong and tough paperboard according to claim 1, characterized in that, The cardboard layer is made of recyclable material.

8. The multi-layer strong and tough paperboard according to claim 7, characterized in that, The yellow cardboard layer is made of recycled pulp.

9. The multi-layer strong and tough paperboard according to claim 1, characterized in that, The yellow cardboard layer has ventilation holes that extend through its surface.

10. The multi-layer strong and tough paperboard according to claim 9, characterized in that, The vent is a round hole.

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