Outdoor composite plywood floor

Abstract

The utility model belongs to the technical field of artificial boards, and particularly discloses an outdoor composite plywood floor. The outdoor composite plywood floor comprises a core layer, secondary surface layers arranged on the two opposite surfaces of the core layer, surface layers arranged on the outer sides of the two secondary surface layers and protective coatings arranged on the outer sides of the two surface layers. Wherein the core layer comprises a plurality of layers of rift-grain veneers which are sequentially laminated, the secondary surface layer is a cross-grain veneer, and the surface layer is a rift-grain veneer. According to the outdoor composite plywood floor, the multiple layers of rift grain veneers are sequentially stacked, the beam effect is effectively formed, and the flexural rigidity of the rift grain veneers is intensively improved; the transverse grain veneer on the secondary surface layer can effectively restrain transverse shrinkage stress generated by the rift grain veneer on the core layer, and the warping rate of the board is reduced; the rift-grain veneer on the surface layer can provide a flat plate base surface so as to enhance the adhesive force of the protective coating on the rift-grain veneer, and meanwhile, the rift-grain bending resistance is secondarily enhanced. By improving the structure of the plywood, the requirement for high performance of the outdoor floor is met economically and environmentally friendly.

Description

Technical Field

[0001] This utility model belongs to the field of engineered wood products technology, and more specifically, it relates to an outdoor composite plywood flooring that combines high strength and good protective performance. Background Technology

[0002] Most existing outdoor flooring is made from preservative-treated solid wood (such as Scots pine) or WPC (wood-plastic composite). For example, Chinese patent CN207003919U discloses an outdoor wood-plastic flooring that has preservative-treated solid wood, a heat insulation layer, a preservative layer, an elastic layer, and a plastic layer arranged sequentially from top to bottom in the inner cavity of the flooring. Drainage holes are opened on the sides, grooves are opened on both sides, and a material-saving groove is opened at the bottom. The elastic layer and the preservative layer make the flooring less prone to cracking and deformation. The heat insulation layer prevents the flooring from being affected by heat. The drainage holes reduce the erosion of the flooring by rainwater. The plastic layer protects the preservative-treated solid wood from surface erosion and has a water-permeable function. For example, Chinese patent CN108973283A discloses an outdoor composite wood-plastic flooring and its manufacturing method. It is made from wood-plastic composite layers A, B, and C through a hot-pressing process. Graphene oxide-modified polyurethane elastomer is added to both layers A and C to increase the flooring's impact resistance, mechanical strength, and abrasion resistance. Rare earth modified plastics are added to layer B to further improve the flooring's impact resistance and heat stability. Rosin is added to all three layers to improve the compatibility between plant fiber raw materials and polyvinyl chloride (PVC) plastic, reducing the flooring's water absorption. However, the former technology, using preservative-treated solid wood as raw material, often suffers from high costs and the depletion of natural forest resources, while the latter, WPC material, contains plastic components that are difficult to degrade. Neither of these approaches aligns with the development trend and requirements of green building.

[0003] Therefore, it is necessary to conduct further research on outdoor flooring to meet the performance requirements of high strength and good protective properties (weather resistance, abrasion resistance, etc.) in harsh outdoor environments, while also taking into account the needs of economy and environmental protection.

[0004] Meanwhile, plywood, as one of the most important engineered wood products, has advantages such as low cost, relative environmental friendliness, and mature manufacturing processes. However, traditional plywood often uses a cross-grain veneer assembly method (meaning the grain direction of each adjacent pair of veneers is perpendicular). While this technology can balance the anisotropy of the veneers, the static bending strength along the grain direction is insufficient for high-load-bearing applications such as outdoor flooring. Especially when plywood is exposed to harsh outdoor environments with high humidity and large temperature fluctuations for extended periods, it is prone to deformation, cracking, or delamination, resulting in a shorter lifespan.

[0005] In conclusion, if plywood can be improved to meet the performance requirements of outdoor flooring, such as high strength and good protection, it will greatly benefit the economical and environmentally friendly development of the outdoor flooring industry. Utility Model Content

[0006] To address the issues of current outdoor flooring failing to meet green and environmental protection requirements due to the consumption of natural forestry resources and the non-degradable nature of plastic components, as well as the inability of traditional plywood to meet stringent outdoor performance demands, this invention improves the structure of plywood, giving it both high strength and good protective properties, thus meeting the performance requirements of outdoor flooring. At the same time, it remains a type of plywood and also has the advantages of being economical and environmentally friendly.

[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0008] An outdoor composite plywood flooring, comprising:

[0009] The core layer consists of multiple layers of parallel-grained veneers stacked sequentially;

[0010] The secondary surface layer is set on the two opposite surfaces of the core layer, and both surface layers are horizontal striped veneers.

[0011] The surface layer is set on the surface of the two surface layers that is far away from the core layer, and both surface layers are veneers with parallel grain.

[0012] A protective coating is applied to the surface of the two outer layers, away from the core layer.

[0013] This outdoor composite plywood flooring utilizes a multi-layered, parallel-grained veneer stacking technique. Firstly, this technique effectively creates a "beam effect," providing core strength for the flooring. Compared to alternating layers of parallel and cross-grained veneers, this method concentrates the bending stiffness of the parallel-grained veneers, effectively overcoming the drawback of insufficient static bending strength in the parallel grain direction to meet the requirements of high-performance boards. Secondly, the two surface layers are positioned on opposite sides of the core layer, using cross-grained veneers perpendicular to the core. This balances lateral stress and effectively suppresses lateral shrinkage stress in the parallel-grained veneers caused by temperature and humidity changes, thus reducing warping. Finally, the use of parallel-grained veneers perpendicular to the sub-surface layer provides a smooth surface, enhancing the adhesion of the protective coating and further strengthening the parallel-grained bending resistance.

[0014] Optionally, the core layer comprises 5 to 7 layers of parallel-grained veneer stacked sequentially.

[0015] Fewer layers may lead to a significant reduction in longitudinal bending strength (such as load-bearing capacity), which can easily cause fracture, especially under long-term outdoor loads. On the other hand, more layers can lead to large differences in transverse and longitudinal anisotropy, and stress accumulation in the longitudinal direction, which can cause cracks or delamination after long-term use. Neither of these can meet the harsh environment of outdoor flooring.

[0016] Optionally, the thickness of each parallel-grained veneer used to form the core layer is 1.8 mm to 3.0 mm.

[0017] Optionally, the thickness of each layer of cross-grain veneer used to form the sub-surface layer is 1.2 mm to 2.0 mm.

[0018] Optionally, the thickness of each layer of parallel-grain veneer used to form the surface layer is 0.8 mm to 1.5 mm.

[0019] Optionally, both parallel-grain veneers and cross-grain veneers are made of high density (density of 600 kg / m³). 3 ~1000kg / m 3 The veneer is made of birch or eucalyptus wood and has a moisture content of no more than 10%.

[0020] Each pair of adjacent veneers in the core layer, sub-layer, and top layer is connected by adhesive.

[0021] Preferably, phenolic adhesive is used as the adhesive for bonding the individual veneers.

[0022] Optionally, the protective coating includes an anti-mildew layer, a putty layer, and a UV topcoat layer applied sequentially on the surface.

[0023] Preferably, the protective coating further includes a transition bonding layer coated between the anti-mildew layer and the putty layer; wherein the transition bonding layer is a structural layer formed using a silane coupling agent as a material.

[0024] Optionally, the wet film thickness of the anti-mildew layer is 0.08 mm to 0.18 mm.

[0025] Furthermore, the anti-mildew layer is a dense structural layer formed by spraying or rolling an anti-mildew agent and then drying it.

[0026] Furthermore, the antifungal agent can be selected from conventional commercially available antifungal products such as isothiazolinone, quaternary ammonium copper, and nano silver / zinc oxide antifungal agents.

[0027] Optionally, the thickness of the putty layer can be 0.3mm to 0.6mm.

[0028] Optionally, the dry film thickness of the UV topcoat layer is 100μm to 180μm.

[0029] Furthermore, the UV topcoat layer is a dense, non-porous film layer formed by drying and curing UV topcoat as the material.

[0030] Furthermore, the UV topcoat can be selected from conventional commercially available UV topcoat products such as UV polyurethane topcoat, UV acrylic topcoat, and UV epoxy resin topcoat.

[0031] This utility model has the following beneficial effects:

[0032] 1) This outdoor composite plywood flooring, through the directional reinforcement design of "multi-layer parallel grain core layer + cross grain sub-surface layer + parallel grain surface layer", breaks the traditional balanced cross and parallel grain sequential stacking pattern, and concentrates to improve the parallel grain static bending strength, so that the obtained plywood meets the high strength performance.

[0033] 2) This outdoor composite plywood flooring uses a composite protective coating of "anti-mildew agent-putty-UV topcoat" to form a gradient protective barrier through multiple surface treatment methods, which improves the weather resistance, surface durability and other protective performance of the outdoor composite plywood flooring, making it suitable for high-load, humid and variable outdoor environments.

[0034] 3) This outdoor composite plywood flooring still has the overall structure of plywood, which has the advantages of plywood such as readily available raw materials, mature technology, economy and environmental protection. It avoids the use of natural forest resources such as anti-corrosion solid wood, and does not contain non-environmentally friendly components such as plastics. Attached Figure Description

[0035] Figure 1 This is a structural schematic diagram of an outdoor composite plywood floor according to an embodiment of the present utility model;

[0036] Figure 2 yes Figure 1 A schematic diagram of the structure of a core layer;

[0037] Figure 3 yes Figure 2 A schematic diagram of the structure of a protective coating;

[0038] Figure 4 yes Figure 2 A schematic diagram of another type of protective coating. Detailed Implementation

[0039] To enable those skilled in the art to better understand the solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0040] In the description of this utility model, it should be understood that the terms "thickness," "upper," "lower," etc., indicate the orientation or state relationship based on the orientation or state relationship shown in the accompanying drawings. These terms are mainly for the purpose of better describing this utility model and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0041] Furthermore, in addition to indicating location or state relationships, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0042] See Figure 1 An embodiment of this utility model provides an outdoor composite plywood floor, which includes a core layer 1, a sub-surface layer 2 located on the upper and lower surfaces of the core layer 1, a surface layer 3 located on the surface of the sub-surface layer 2 away from the core layer 1, and a protective coating 4 located on the surface of the surface layer 3 away from the core layer 1.

[0043] Specifically, the core layer 1 comprises multiple layers of parallel-grained veneers stacked sequentially (hereinafter referred to as core layer parallel-grained veneers).

[0044] Both the upper surface layer 21 and the lower surface layer 22 are formed by a single layer of horizontal stripe veneer.

[0045] Both the upper surface layer 31 and the lower surface layer 32 are formed by a single layer of parallel-grained veneer.

[0046] Thus, the resulting outdoor composite plywood flooring has a main structure with a "straight grain - cross grain - multiple layers of straight grain - cross grain - straight grain" assembly method. Firstly, multiple layers of straight-grain veneers are stacked sequentially to form the core layer, effectively creating a "beam effect" and concentrating on improving the bending stiffness of the straight-grain veneers, serving as the core strength structural layer of the flooring. Secondly, a layer of cross grain veneer is set on each of the two opposite surfaces of the core layer 1 as a secondary surface layer, which is arranged perpendicularly to the straight-grain veneers in the adjacent core layer 1, balancing the transverse grain. The stress can effectively suppress the transverse shrinkage stress caused by temperature and humidity changes in the core layer veneer of the core layer 1, thereby reducing the warping rate of the entire floor; thirdly, a layer of veneer with the same grain is set on the outer side of the two layers of cross-grain veneer (with the side of the cross-grain veneer adjacent to the core layer 1 as the inner side), which is arranged perpendicularly to the adjacent cross-grain veneer again. This not only strengthens the bending resistance of the cross grain for a second time, but also provides a flat board base surface to enhance the adhesion of the surface treatment layer (i.e., the protective coating 4 applied to the surface layer 3).

[0047] The core layer 1 preferably has 5 to 7 layers of parallel-grained veneers.

[0048] Further integration Figure 2 The diagram shows a core layer formed by sequentially stacking six layers of parallel-grained veneer 1a.

[0049] As can be seen from the above, both the sub-layer 2 and the surface layer 3 include two structural layers dispersed on both sides of the core layer 1.

[0050] For ease of description, the term "upper sublayer 21" will be used to refer to the sublayer located above core layer 1 in the diagram, and "lower sublayer 22" will be used to refer to the sublayer located below core layer 1 in the diagram. Similarly, "upper sublayer 31" will be used to refer to the sublayer located above upper sublayer 21 in the diagram, and "lower sublayer 32" will be used to refer to the sublayer located below lower sublayer 22 in the diagram.

[0051] In each core layer parallel-grain veneer 1a, the horizontal-grain veneer used to form the sub-surface layer, and the parallel-grain veneer used to form the surface layer, every two adjacent veneers are bonded together by adhesive.

[0052] Preferably, a phenolic adhesive is used for bonding. Phenolic adhesives can be purchased from any commercially available product or synthesized using any existing technology.

[0053] The core component of phenolic adhesives is phenolic resin, which has a three-dimensional cross-linked structure. The structure is dense and stable, making it difficult for water molecules to penetrate or break the chemical bonds. It also contains a large number of benzene ring structures. The strong hydrophobicity of the benzene rings can effectively repel water, reduce the water absorption rate of the formed adhesive layer, and thus improve the weather resistance of the entire floor.

[0054] The thickness of the core layer parallel-grain veneer 1a is generally controlled to be 1.8mm to 3.0mm; the thickness of the horizontal-grain veneer used to form the secondary surface layer is generally controlled to be 1.2mm to 2.0mm; and the thickness of the parallel-grain veneer used to form the surface layer is generally controlled to be 0.8mm to 1.5mm.

[0055] The core layer veneer 1a, the veneer used to form the sub-layer, and the veneer used to form the surface layer are all high-density birch or eucalyptus veneers with a density of 600 kg / m³. 3 ~1000kg / m 3 The moisture content of these materials is all less than 10% (≤10%), indicating low moisture content. High-density birch or eucalyptus veneers are used as the core, sub-layer, and surface layers. These high-density veneers are based on wood with thicker cell walls and smaller cell cavities, forming a dense microstructure. Water cannot easily penetrate the wood quickly through capillary action, resulting in a significantly lower water absorption rate compared to low-density woods (such as pine, with a density of 400 kg / m³). 3 ~500kg / m 3 It can effectively resist moisture penetration and reduce expansion and deformation in high humidity outdoor environments.

[0056] The protective coating 4 has a multi-layer structure.

[0057] Reference Figure 3 As shown, in some embodiments, the protective coating 4 includes an anti-mildew layer 41, a putty layer 42, and a UV topcoat layer 43 sequentially coated on the surface layer 3.

[0058] Specifically, according to Figure 3 As shown, an upper anti-mildew layer 411, an upper putty layer 421, and an upper UV topcoat layer 431 are sequentially coated above the upper surface layer 31; and a lower anti-mildew layer 412, a lower putty layer 422, and a lower UV topcoat layer 432 are sequentially coated below the lower surface layer 32.

[0059] The anti-mold layer 41 is a dense anti-mold barrier formed by applying an anti-mold agent through a spraying or roller coating process and then drying it to inhibit the growth of fungi.

[0060] The wet film thickness of the anti-mildew layer 41 should be controlled between 0.08mm and 0.18mm.

[0061] Generally, antifungal agents can be selected from conventional commercially available antifungal products such as isothiazolinone, quaternary ammonium copper, and nano silver / zinc oxide antifungal agents.

[0062] The putty layer 42 is a structural layer formed by applying putty to the anti-mildew layer 41. It is used to fill the micropores on the surface of the veneer of the surface layer 3 and improve the smoothness of the subsequent paint film.

[0063] The thickness of the putty layer 42 should be controlled between 0.3mm and 0.6mm.

[0064] The UV topcoat layer 43 is a dense, non-porous film layer formed by applying UV topcoat to the putty layer 42 and then drying and curing it. It effectively prevents moisture from penetrating into the wood, blocks the growth environment of fungi and bacteria, and prevents the veneer from absorbing water, swelling, deforming, or becoming moldy, thereby improving the waterproof, mildew-proof, and corrosion-resistant properties of the flooring.

[0065] Meanwhile, UV topcoats typically contain hard particle functional fillers that form a high-strength cross-linked network through UV curing, increasing the surface hardness of the flooring. Furthermore, the photoinitiators in UV topcoats absorb or scatter ultraviolet light (wavelength 280nm–400nm), reducing degradation of the wood veneer and coating, and improving the flooring's resistance to aging.

[0066] The dry film thickness of the UV topcoat layer 43 should be controlled between 100μm and 180μm.

[0067] Generally, UV topcoats can be selected from conventional commercially available UV topcoat products such as UV polyurethane topcoats, UV polyester topcoats, and UV epoxy resin topcoats.

[0068] In this way, a gradient protection system of "anti-mildew agent - putty - UV topcoat" is formed, and multiple surface treatments are carried out to form a gradient protective barrier, which improves the weather resistance and surface durability of the floor, making it suitable for high-load, humid and variable outdoor environments.

[0069] Reference Figure 4 As shown, in some embodiments, the protective coating 4 includes an anti-mildew layer 41, a transition bonding layer 44, a putty layer 42, and a UV topcoat layer 43 sequentially coated on the surface layer 3.

[0070] Specifically, according to Figure 4 As shown, the upper surface layer 31 is sequentially coated with an upper anti-mildew layer 411, an upper putty layer 421, an upper transition bonding layer 441, and an upper UV topcoat layer 431; the lower surface layer 32 is sequentially coated with a lower anti-mildew layer 412, a lower transition bonding layer 442, a lower putty layer 422, and a lower UV topcoat layer 432.

[0071] The anti-mold layer 41 is a dense anti-mold barrier formed by applying an anti-mold agent to the surface layer 3 by spraying or rolling and then drying it, so as to inhibit the growth of fungi.

[0072] The wet film thickness of the anti-mildew layer 41 should be controlled between 0.08mm and 0.18mm.

[0073] Generally, antifungal agents can be selected from conventional commercially available antifungal products such as isothiazolinone, quaternary ammonium copper, and nano silver / zinc oxide antifungal agents.

[0074] The transition layer 44 is a structural layer formed by applying a silane coupling agent to the anti-mildew layer 41. The transition layer 44 optimizes gradient protection and enhances the interfacial bonding between the anti-mildew layer 41 and the putty layer 42.

[0075] The putty layer 42 is a structural layer formed by applying putty to the transition bonding layer 44 to fill the micropores on the surface of the veneer of the surface layer 3 and improve the smoothness of the subsequent paint film.

[0076] The thickness of the putty layer 42 should be controlled between 0.3mm and 0.6mm.

[0077] The UV topcoat layer 43 is a dense, non-porous film layer formed by applying UV topcoat to the putty layer 42 and then drying and curing it. It effectively prevents moisture from penetrating into the wood, blocks the growth environment of fungi and bacteria, and prevents the veneer from absorbing water, swelling, deforming, or becoming moldy, thereby improving the waterproof, mildew-proof, and corrosion-resistant properties of the flooring.

[0078] Meanwhile, UV topcoats typically contain hard particle functional fillers that form a high-strength cross-linked network through UV curing, increasing the surface hardness of the flooring. Furthermore, the photoinitiators in UV topcoats absorb or scatter ultraviolet light (wavelength 280nm–400nm), reducing degradation of the wood veneer and coating, and improving the flooring's resistance to aging.

[0079] The dry film thickness of the UV topcoat layer 43 should be controlled between 100μm and 180μm.

[0080] Generally, UV topcoats can be selected from conventional commercially available UV topcoat products such as UV polyurethane topcoats, UV polyester topcoats, and UV epoxy resin topcoats.

[0081] Thus, based on the main gradient protection system of "anti-mildew agent-putty-UV topcoat", a transitional connecting layer 44 made of silane coupling agent is set between the anti-mildew layer and the putty layer to further enhance the bonding force between the anti-mildew agent and the putty, reduce the risk of the putty layer 42 and the UV topcoat layer 43 falling off, and further improve the weather resistance and surface durability of the floor.

[0082] The following specific examples will demonstrate the above-mentioned outdoor composite plywood flooring and its effects.

[0083] Example 1

[0084] In this embodiment, refer to Figure 1 , Figure 3 As shown, the provided outdoor composite plywood flooring includes a lower surface layer 32, a second lower surface layer 22, a core layer 1, an upper second surface layer 21, and an upper surface layer 31 arranged in sequence. The lower surface layer 32 is coated with a lower anti-mildew layer 412, a lower putty layer 422, and a lower UV topcoat layer 432 in sequence, and the upper surface layer 31 is coated with an upper anti-mildew layer 411, an upper putty layer 421, and an upper UV topcoat layer 431 in sequence.

[0085] The core layer 1 is formed by five layers of core layer veneer bonded together in sequence.

[0086] Example 2

[0087] In this embodiment, refer to Figure 1 , Figure 4 As shown, the provided outdoor composite plywood flooring includes a lower surface layer 32, a second lower surface layer 22, a core layer 1, an upper second surface layer 21, and an upper surface layer 31 arranged in sequence. The lower surface layer 32 is coated with a lower anti-mildew layer 412, a lower transition layer 442, a lower putty layer 422, and a lower UV topcoat layer 432 in sequence. The upper surface layer 31 is coated with an upper anti-mildew layer 411, an upper transition layer 441, an upper putty layer 421, and an upper UV topcoat layer 431 in sequence.

[0088] The core layer 1 is formed by seven layers of core layer veneer bonded together in sequence.

[0089] The following are the performance test results of the outdoor composite plywood flooring provided in the above embodiments.

[0090] The static bending strength test shall be performed in accordance with the provisions of section 4.8 of GB / T 17657-2022.

[0091] Table 1. Test results of static bending strength of outdoor composite plywood flooring provided in the embodiments.

[0092]

[0093] Meanwhile, a 5-hour boiling test was conducted on the outdoor composite plywood flooring provided in the two embodiments above. After 5 hours of boiling and soaking treatment, its bending cracking degree also met the requirements, and no obvious bending cracking occurred.

[0094] As shown in Table 1, the outdoor composite plywood flooring provided in the embodiments of this utility model has good static bending strength and meets the standard in the 5-hour boiling test, thus satisfying the corresponding performance requirements of outdoor flooring.

[0095] In the description of this specification, the reference to the term "some embodiments" means that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0096] 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 of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. An outdoor composite plywood flooring, characterized by, include: The core layer consists of multiple layers of parallel-grained veneers stacked sequentially; The secondary surface layer is disposed on two opposite surfaces of the core layer, and both secondary surface layers are horizontal striped veneers; The surface layer is disposed on the surface of the sub-surface layer away from the core layer, and both surface layers are parallel-grained veneers; And a protective coating, applied to the surface of the outer layer away from the core layer.

2. The outdoor composite plywood flooring according to claim 1, wherein, The core layer comprises 5 to 7 layers of parallel-grained veneer stacked sequentially.

3. The outdoor composite plywood flooring according to claim 1 or 2, characterized in that, The thickness of each parallel-grained veneer used to form the core layer is 1.8 mm to 3.0 mm.

4. The outdoor composite plywood flooring of claim 1, wherein, The thickness of each horizontally grained veneer used to form the subsurface layer is 1.2 mm to 2.0 mm, and / or the thickness of each parallel-grained veneer used to form the surface layer is 0.8 mm to 1.5 mm.

5. The outdoor composite plywood flooring of claim 1, wherein, The parallel-grain veneer and the cross-grain veneer can be either birch veneer or eucalyptus veneer.

6. The outdoor composite plywood flooring according to claim 1 or 2, wherein The protective coating comprises an anti-mildew layer, a putty layer, and a UV topcoat layer, which are sequentially applied to the surface layer.

7. The outdoor composite plywood flooring of claim 6, wherein, The wet film thickness of the anti-mildew layer is 0.08mm to 0.18mm, the scraping thickness of the putty layer is 0.3mm to 0.6mm, and the dry film thickness of the UV topcoat layer is 100μm to 180μm.

8. The outdoor composite plywood flooring according to claim 1 or 2, wherein, The protective coating comprises an anti-mildew layer, a transition layer, a putty layer, and a UV topcoat layer, which are sequentially layered on the surface; wherein the transition layer is a connecting structure layer formed using a silane coupling agent.

9. The outdoor composite plywood flooring according to claim 8, characterized in that, The wet film thickness of the anti-mildew layer is 0.08mm to 0.18mm, the scraping thickness of the putty layer is 0.3mm to 0.6mm, and the dry film thickness of the UV topcoat layer is 100μm to 180μm.

10. The outdoor composite plywood flooring according to claim 1 or 2, wherein, In the outdoor composite plywood flooring, each pair of adjacent veneers is bonded together with adhesive.

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