Support Board for Formwork Made from Indonesian Rubber Tree with Latex Removed Using Laminated Veneer Process and Manufacturing Method thereof

Abstract

A waterproof plywood for formwork made from Indonesian rubber wood with a laminated veneer structure according to the present invention is formed into a plate shape comprising a plurality of veneer layers laminated by filling Indonesian rubber wood from which latex has been removed to a thickness less than or equal to a predetermined standard thickness, wherein the plurality of veneer layers are bonded by an adhesive resin and compressed, and a waterproof film may be attached to the construction surface that contacts the formwork.

Description

Technology Field

[0001] The present invention relates to a waterproof plywood for formwork and a method for manufacturing the same, and more specifically, to a waterproof plywood for formwork formed by laminating thinly peeled veneers of Indonesian rubberwood from which the latex has been removed, and having a waterproof film attached to the construction surface, and a method for manufacturing the same. Background Technology

[0002] Formwork is used to cure concrete into desired shapes when constructing concrete structures at construction sites. Formwork serves to support the concrete from the time of pouring until curing is complete, and it is common practice to reuse it after demolding for repeated use. Various types of wooden planks have been used as formwork materials, and the quality of the surface in direct contact with the concrete has a direct influence on determining the surface quality of the final construction product.

[0003] Wooden planks used as formwork materials require resistance to moisture during contact with concrete. Concrete contains a large amount of moisture upon pouring and continues to generate moisture during the curing process. Repeated exposure of wooden planks to such moisture can reduce the bonding strength between the wood layers, leading to problems such as surface delamination or warping. Furthermore, the sides and corners of wooden planks are often insufficiently waterproofed, allowing moisture to penetrate inward and cause interlayer delamination and decay.

[0004] Furthermore, wooden formwork panels had problems such as uneven strength depending on the grain direction and reduced dimensional stability due to repeated expansion and contraction caused by moisture. Such issues reduced the reuse frequency of the formwork and consequently caused an increase in construction costs.

[0005] Meanwhile, although rubber trees are widely cultivated as a latex-producing species, their use in wood products has been limited due to the latex content. Most rubber trees after latex extraction have been discarded or utilized only for low-value purposes; however, with the recent rise in interest in environmental protection and resource recycling, attempts are being made to convert these discarded rubber trees into useful wood resources.

[0006] Therefore, there is a need for a new formwork panel structure and manufacturing method that can solve the problems of wood strength and dimensional stability, improve waterproofing performance, and efficiently utilize discarded rubberwood. Prior art literature

[0007] Korean Utility Model Registration No. 20-0394606 The problem to be solved

[0008] The present invention is an invention devised to solve the problems of the aforementioned prior art, and aims to provide a waterproof plywood for formwork with improved waterproofing performance and dimensional stability by forming a laminated structure of veneers thinly peeled from Indonesian rubberwood with the latex removed and attaching a waterproof film to the construction surface, and a method for manufacturing the same.

[0009] The problems of the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0010] The waterproof plywood for formwork using Indonesian rubber wood as a raw material and having a laminated veneer structure according to the present invention for achieving the above-mentioned purpose is formed into a plate shape comprising a plurality of veneer layers laminated by filling Indonesian rubber wood from which latex has been removed to a thickness less than or equal to a predetermined standard thickness, wherein the plurality of veneer layers are bonded by an adhesive resin and compressed, and a waterproof film may be attached to the construction surface that contacts the formwork.

[0011] In addition, the plurality of veneer layers can be laminated such that the grain direction of each veneer layer is oriented in the same direction.

[0012] At this time, the plurality of veneer layers can be interlaced such that the grain directions of adjacent veneer layers are orthogonal to each other.

[0013] And the above waterproof film can be formed by impregnating paper with phenol-formaldehyde resin.

[0014] Meanwhile, a waterproof film may be additionally attached to the back surface formed on the opposite side of the above-mentioned construction surface.

[0015] In addition, a waterproof resin may be applied to the perimeter of the aforementioned plurality of veneer layers.

[0016] Furthermore, the method for manufacturing a waterproof plywood for formwork using Indonesian rubber wood as a raw material having a laminated veneer structure according to the present invention for achieving the above-mentioned purpose may include the following steps: (a) preparing Indonesian rubber wood from which the latex has been removed; (b) producing a plurality of veneer layers by filling the rubber wood to a thickness less than or equal to a predetermined standard thickness; (c) applying an adhesive resin to the plurality of veneer layers; (d) laminating the plurality of veneer layers coated with the adhesive resin; (e) compressing the plurality of veneer layers laminated by step (d) to form a waterproof plywood for formwork in the shape of a plate; and (f) attaching a waterproof film to the construction surface of the waterproof plywood for formwork that contacts the formwork.

[0017] In addition, step (f) above may additionally attach a waterproof film to the back surface formed on the opposite side of the construction surface.

[0018] In addition, after step (f) above, step (g) of applying a waterproof resin to the periphery of the plurality of veneer layers may be further included.

[0019] Meanwhile, in step (g) above, the waterproof resin can be applied stepwise in the order of the perimeter surface, the corners where the perimeter surfaces meet, and the vertices where the corners meet. Effects of the invention

[0020] The waterproof plywood for formwork using Indonesian rubber wood with a laminated veneer structure according to the present invention, and the method for manufacturing the same, which solves the above-mentioned problem, have the advantage of providing an environmentally friendly and economical waterproof plywood for formwork by utilizing Indonesian rubber wood from which latex has been removed as a raw material, thereby enabling the recycling of resources that were previously discarded.

[0021] In addition, the present invention has the advantage of improving the quality uniformity and dimensional stability of waterproof plywood for formwork by forming a laminated structure by bonding a plurality of thinly peeled veneer layers of rubber wood with an adhesive resin, thereby minimizing defects such as knots and cracks in the wood and reducing variations in strength along the grain direction.

[0022] Therefore, the present invention has the advantage of extending the reuse cycle of waterproof plywood for formwork and reducing construction costs by preventing interlayer delamination and decay caused by moisture generated during the concrete pouring and curing process through the attachment of a waterproof film to the construction surface in contact with the formwork. Brief explanation of the drawing

[0023] FIG. 1 is a drawing showing the appearance of a waterproof plywood for formwork made from Indonesian rubber wood with a laminated veneer structure according to one embodiment of the present invention. FIG. 2 is a drawing showing the structure of a waterproof plywood for formwork made from Indonesian rubber wood with a laminated veneer structure according to one embodiment of the present invention. FIG. 3 is a diagram showing each process of a method for manufacturing waterproof plywood for formwork using Indonesian rubber wood from which latex has been removed as a raw material, according to one embodiment of the present invention. Specific details for implementing the invention

[0024] In this specification, where a component (or region, layer, part, etc.) is described as being "on," "connected," or "combined" with another component, it means that it may be directly placed / connected / combined with the other component, or that a third component may be placed between them.

[0025] Identical reference numerals denote identical components. Additionally, in the drawings, the thicknesses, proportions, and dimensions of the components are exaggerated for the effective illustration of the technical content.

[0026] "And / or" includes all one or more combinations that the associated configurations can define.

[0027] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0028] Additionally, terms such as "below," "lower side," "above," and "upper side" are used to describe the relationships between the components depicted in the drawings. These terms are relative concepts and are described based on the directions indicated in the drawings.

[0029] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Additionally, terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and are explicitly defined herein unless interpreted in an ideal or overly formal sense.

[0030] Terms such as "include" or "have" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0032] FIG. 1 is a drawing showing the appearance of a waterproof plywood (100) for formwork made from Indonesian rubber wood with a laminated veneer structure according to one embodiment of the present invention, and FIG. 2 is a drawing showing the structure of a waterproof plywood (100) for formwork made from Indonesian rubber wood with a laminated veneer structure according to one embodiment of the present invention.

[0033] The waterproof plywood (100) for formwork according to the present invention can be used as a material for formwork to cure concrete into a desired shape at a construction site. The waterproof plywood (100) for formwork includes a construction surface that comes into direct contact with concrete and can be equipped with waterproofing performance to prevent interlayer delamination and decay even when exposed to moisture generated during the concrete pouring and curing process. The waterproof plywood (100) for formwork can be reused repeatedly after demolding and can be continuously utilized as long as its waterproofing performance is maintained.

[0034] As illustrated in FIGS. 1 and 2, a waterproof plywood (100) for formwork according to one embodiment of the present invention may be formed into a plate shape by including a plurality of veneer layers (110) laminated by filling Indonesian rubber wood from which latex has been removed to a thickness less than or equal to a predetermined standard thickness.

[0035] Rubber trees are widely cultivated as a species that produces latex, but their use in wood products has been limited due to the latex components contained within them. Therefore, most rubber trees from which latex has been harvested have been discarded or used only for low-value-added purposes. However, in the present invention, the recycling of waste resources can be realized by utilizing rubber trees from which latex has been removed as raw materials for waterproof plywood (100) for formwork.

[0036] Multiple veneer layers (110) can be produced by filling rubber wood into a thin sheet form. The filling process can be performed by rotating the raw wood and thinly slicing it with a blade, thereby producing veneer layers (110) with a uniform thickness. A pre-set standard thickness can be set considering the quality and lamination efficiency of the veneer layers (110), and by forming the veneer layers (110) thinly, defects such as knots and cracks present in the raw wood can be prevented from affecting the entire veneer layer (110).

[0037] A plurality of veneer layers (110) can be formed by compression bonding with an adhesive resin. The adhesive resin can be applied between the veneer layers (110) to provide bonding strength between the veneer layers (110), and various types of adhesive resins such as phenolic resin, urea resin, and melamine resin can be used.

[0038] A plurality of veneer layers (110) coated with adhesive resin can be laminated and then compressed to be integrally bonded, and the compression process can be performed using a cold pressing method or a hot pressing method. The cold pressing method is a method of curing the adhesive resin by applying pressure at room temperature, and the hot pressing method is a method of promoting the curing of the adhesive resin by applying heat and pressure simultaneously.

[0039] Meanwhile, in the present invention, a plurality of veneer layers (110) may be laminated such that the grain direction of each veneer layer (110) is oriented in the same direction. The grain direction of the veneer layer (110) refers to the direction in which the wood fibers extend, and if all veneer layers (110) are laminated with the grain direction oriented in the same direction, the strength in a specific direction can be improved.

[0040] In addition, in the present invention, a plurality of veneer layers (110) may be cross-stacked such that the grain directions of adjacent veneer layers (110) are orthogonal to each other. When the grain directions of adjacent veneer layers (110) are cross-stacked so that they are orthogonal to each other, the waterproof plywood (100) for formwork can have uniform strength in all directions. That is, the difference in strength between the length direction and the width direction is reduced, so that it can be stably supported regardless of which direction a load is applied, and resistance to twisting or bending can also be improved.

[0041] A waterproof film (120) may be attached to the construction surface of the waterproof plywood (100) for formwork that comes into contact with the formwork. The waterproof film (120) can block moisture from penetrating into the waterproof plywood (100) for formwork through the construction surface, and can maintain the interlayer bonding strength of the waterproof plywood (100) for formwork even when repeatedly exposed to moisture generated during the concrete pouring and curing process.

[0042] The waterproof film (120) may be a film formed by impregnating a paper with phenol-formaldehyde resin. The phenol-formaldehyde resin has excellent water resistance and heat resistance, so it can secure resistance to moisture and heat in a concrete pouring environment, and by impregnating the paper, it can improve the shape stability of the waterproof film (120). The density of the waterproof film (120) may be formed in the range of 120 gsm to 180 gsm, and as the density is lower, flexibility is improved, and as the density is higher, waterproof performance and durability can be improved.

[0043] In addition, in this embodiment, the waterproof film (120) can be additionally attached to the back side formed on the opposite side of the construction surface, thereby protecting both sides of the waterproof plywood (100) for formwork from moisture.

[0044] Additionally, a waterproof resin (130) may be applied to the perimeter of the plurality of veneer layers (110). The waterproof resin (130) may serve to prevent moisture from penetrating into the interior through the perimeter forming the side of the waterproof plywood (100) for formwork.

[0045] The waterproof resin (130) may include at least one of the synthetic resin series waterproof resins such as epoxy resin, urethane resin, acrylic resin, silicone resin, etc., and an appropriate type may be selected depending on the usage environment and required waterproof performance.

[0046] Such waterproof resin (130) can be applied step by step in the order of the perimeter surface, the corners where the perimeter surfaces meet, and the vertices where the corners meet. By first applying the waterproof resin (130) to the perimeter surface, then treating the corners, and finally treating the vertices, the waterproof resin (130) can be applied without gaps to all exposed parts of the waterproof plywood (100) for formwork.

[0047] FIG. 3 is a diagram showing each process of a method for manufacturing waterproof plywood for formwork using Indonesian rubber wood from which latex has been removed as a raw material, according to one embodiment of the present invention.

[0048] As illustrated in FIG. 3, the method for manufacturing waterproof plywood for formwork in the present invention may include steps (a), (b), (ex1), (c), (d), (e), (ex2), (f), and (g).

[0049] Step (a) is the step of preparing Indonesian rubber trees from which the latex has been removed. In Step (a), rubber trees scheduled for disposal after the latex extraction from the rubber trees is completed can be secured. The rubber trees from which the latex has been removed can be processed into wood and, through a drying process, can be prepared in a state suitable for manufacturing waterproof plywood (100) for formwork.

[0050] Step (b) is a step of producing multiple veneer layers (110) by filling the rubberwood to a thickness less than or equal to a predetermined standard thickness. In Step (b), the prepared rubberwood can be fed into a rotary filling device or a slicing device to produce veneer layers (110) in the form of thin sheets. The rotary filling method is a method of continuously thinning the raw wood with a blade while rotating it, and the slicing method is a method of thinly cutting the raw wood by moving the blade while it is fixed. The filled veneer layers (110) can have a uniform thickness less than or equal to a predetermined standard thickness, thereby ensuring uniform quality of the waterproof plywood (100) for formwork after lamination.

[0051] Step (ex1) is a step of drying multiple veneer layers (110). Step (ex1) can be performed between Step (b) and Step (c) and may be a process of removing moisture contained in the peeled veneer layers (110). The drying of the veneer layers (110) can be performed by natural drying or hot air drying, and can proceed until the moisture content of the veneer layers (110) is reduced to a level suitable for bonding with the adhesive resin. By drying the veneer layers (110), the bonding strength of the adhesive resin is improved, and the dimensional stability of the waterproof plywood (100) for formwork after lamination can be secured.

[0052] (c) Step is a step of applying an adhesive resin to a plurality of veneer layers (110). In step (c), the adhesive resin can be uniformly applied to the surface of the dried veneer layer (110). The adhesive resin can be applied by means such as a roller, spray, or curtain coating, and can be evenly distributed over the entire surface of the veneer layer (110).

[0053] Step (d) is a step of laminating a plurality of veneer layers (110) coated with adhesive resin. In Step (d), the veneer layers (110) coated with adhesive resin can be laminated by stacking them sequentially. During the lamination process, the grain direction of each veneer layer (110) can be oriented in the same direction, or the grain directions of adjacent veneer layers (110) can be arranged in an intersecting manner so that they are orthogonal to each other. Laying so that the grain directions are oriented in the same direction can improve strength in a specific direction, while intersecting so that the grain directions are orthogonal to each other can ensure uniform strength in all directions.

[0054] Step (e) is a step of forming a waterproof plywood (100) for formwork in the shape of a plate by compressing a plurality of veneer layers (110) laminated by Step (d). In Step (e), the laminated veneer layers (110) can be fed into a press device to apply pressure. The compression process can be performed using a cold pressing method or a hot pressing method; the cold pressing method is a method of curing the adhesive resin by applying only pressure at room temperature, and the hot pressing method is a method of promoting the curing of the adhesive resin by applying heat and pressure simultaneously. Once compression is completed, the plurality of veneer layers (110) can be integrally bonded to form a waterproof plywood (100) for formwork in the shape of a plate.

[0055] Step (ex2) is a step of polishing the surface of the waterproof plywood (100) for formwork. Step (ex2) can be performed after Step (e), and the surface of the waterproof plywood (100) for formwork can be smoothed through surface treatment processes such as sanding and polishing. Surface polishing removes surface unevenness that may occur during the compression process and ensures a uniform surface condition before attaching the waterproof film (120).

[0056] Step (f) is a step of attaching a waterproof film (120) to the construction surface that contacts the formwork of the waterproof plywood (100) for formwork. In this embodiment, in step (f), the waterproof film (120) can be attached to the construction surface using a heat-press method. The heat-press method may be a method of firmly bonding the waterproof film (120) to the construction surface by applying heat and pressure simultaneously after placing the waterproof film (120) on the construction surface, and the phenol-formaldehyde resin impregnated in the waterproof film (120) can be strongly bonded to the construction surface as it hardens due to heat.

[0057] In addition, step (f) may also attach a waterproof film (120) to the back side formed on the opposite side of the construction surface, thereby protecting both sides of the waterproof plywood (100) for formwork from moisture.

[0058] Step (g) is a step of applying a waterproof resin (130) to the periphery of a plurality of veneer layers (110). Step (g) can be performed after step (f) and can prevent moisture from penetrating into the interior through the sides of the waterproof plywood (100) for formwork.

[0059] In this embodiment, step (g) may apply the waterproof resin (130) step by step in the order of the perimeter surface, the corners where the perimeter surfaces meet, and the vertices where the corners meet. By first applying the waterproof resin (130) to the perimeter surface, then treating the corners, and finally treating the vertices, the waterproof resin (130) can be applied without gaps to all exposed parts of the waterproof plywood (100) for formwork, and the moisture penetration path can be completely blocked.

[0060] For the above, a waterproof plywood (100) made of Indonesian rubber wood with a laminated veneer structure according to each embodiment of the present invention and a method for manufacturing the same have been described in detail. Below, various structures and processes that can be additionally applied to the present invention will be described.

[0061] In the present invention, step (a) is a step of preparing an Indonesian rubber tree from which the latex has been removed, and in detail may include a process of securing a rubber tree from which the latex has been harvested and a process of removing the latex.

[0062] The process of securing rubber trees for which latex extraction has been completed may involve selecting and securing rubber trees that no longer produce latex after extraction is finished. Rubber trees are felled when their productivity declines following latex extraction for a certain period, and the felled trees may contain residual latex.

[0063] The latex removal process may involve removing residual latex from the secured rubber trees and can be performed using natural drying or heat treatment methods. Natural drying may involve drying the felled rubber trees in a natural state for a specified period to evaporate or solidify the internal moisture and latex components. The natural drying period may vary depending on the size of the rubber trees, climatic conditions, etc., and may continue until the internal moisture content of the rubber trees decreases to a level suitable for wood processing.

[0064] The heat treatment method may involve applying high-temperature steam or hot air to felled rubber trees to melt or expel the internal latex components. Compared to natural drying, the heat treatment method can remove the latex in a shorter time; by placing the rubber trees in a sealed chamber and supplying steam at a predetermined temperature, the latex can be liquefied and then expelled. After heat treatment, the rubber trees can be further dried to control the moisture content.

[0065] In addition, the latex removal process in the present invention may further include a mechanical compression method. The mechanical compression method may be a method of forcibly expelling the internal latex by applying physical pressure to a felled rubber tree. By feeding the rubber tree into a roller press or a hydraulic press and applying pressure in the longitudinal or diametrical direction, the latex inside the rubber tree can be expelled to the outside through the pores between the tissues. The mechanical compression method may be performed in parallel with a natural drying method or a heat treatment method; if mechanical compression is performed while the rubber tree is heated after heat treatment, the viscosity of the latex is lowered, which can improve the expulsion efficiency.

[0066] In addition, the latex removal process in the present invention may further include a chemical treatment method. The chemical treatment method may involve immersing the rubber tree in a treatment solution containing a latex coagulant or a latex decomposer, or applying the treatment solution to the surface of the rubber tree. The latex coagulant can fix the latex so that it does not flow within the wood tissue by solidifying the polymer structure of the latex, while the latex decomposer can minimize the impact during wood processing by breaking down the polymer structure of the latex and converting it into low-molecular-weight substances. After chemical treatment, the rubber tree is washed to remove residual treatment solution, and stability as wood can be ensured through a drying process.

[0067] Furthermore, the latex removal process in the present invention may additionally include a vacuum treatment method. The vacuum treatment method may involve placing the rubber tree inside a sealed vacuum chamber and reducing the pressure inside the chamber to a level lower than atmospheric pressure to evaporate or discharge the latex and moisture inside the rubber tree. Heating the inside of the chamber during the vacuum treatment process can promote the evaporation of latex and moisture, and since evaporation is possible even at low temperatures under a vacuum state, damage to the wood tissue of the rubber tree can be minimized. The vacuum treatment method can shorten the processing time compared to the natural drying method and can uniformly remove latex even from the inside of the rubber tree.

[0068] In this way, in step (a), the latex removal process can be performed by selecting at least one of natural drying, heat treatment, mechanical pressing, chemical treatment, and vacuum treatment methods, or by combining these, and the optimal method can be selected by considering the condition of the rubber tree, treatment time, cost, etc.

[0069] Next, in the present invention, a plurality of veneer layers (110) may be formed with different thicknesses depending on the position of each layer. Among the plurality of veneer layers (110), the veneer layer (110) adjacent to the construction surface direction to which the waterproof film (120) is attached may be formed with a first thickness, and the veneer layer (110) positioned in the central part among the plurality of veneer layers (110) may be formed with a second thickness greater than the first thickness.

[0070] The first thickness can be formed to be smaller than the second thickness, and by forming a thin veneer layer (110) adjacent to the direction of the construction surface, the stress distribution effect can be improved when a load is applied during concrete pouring. The thin veneer layer (110) has densely formed interlayer boundaries so that the load can be distributed over multiple layers and prevent stress from concentrating on a specific layer. In addition, the thin veneer layer (110) can minimize the impact of wood defects on the entire layer, thereby improving the durability of the construction surface.

[0071] By forming the veneer layer (110) placed in the central part thickly to a second thickness, the structural strength of the entire waterproof plywood (100) for formwork can be secured. The central veneer layer (110) can perform the role of supporting the main load of the waterproof plywood (100) for formwork, and by forming it thickly, resistance to bending or deformation can be improved. Therefore, stress distribution and overall strength can be secured simultaneously through a differential thickness structure in which a thin veneer layer (110) is placed in the direction of the construction surface and a thick veneer layer (110) is placed in the central part.

[0072] Next, in the present invention, step (c) may apply different adhesive resins or apply different amounts of adhesive resin depending on the position of the plurality of veneer layers (110). Among the plurality of veneer layers (110), the first adhesive resin may be applied to the outer veneer layer exposed to the outside of the waterproof plywood (100) for formwork, and the second adhesive resin may be applied to the inner veneer layer positioned inside the plurality of veneer layers (110).

[0073] The first adhesive resin may be an adhesive resin with excellent water resistance or weather resistance. Since the outer veneer layer may be repeatedly exposed to external environments such as moisture and temperature changes during the concrete pouring and curing process, applying the first adhesive resin with excellent water resistance and weather resistance can prevent a decrease in bonding strength caused by the external environment. Phenolic resin, melamine resin, etc., may be used as the first adhesive resin, and since it has excellent resistance to moisture, it can maintain the bonded state even during long-term use.

[0074] The second adhesive resin may be an adhesive resin with excellent bonding strength. Since the inner veneer layer is not directly exposed to the external environment, bonding strength may be more important than water resistance, and urea resin, epoxy resin, etc. may be used as the second adhesive resin. The second adhesive resin provides high bonding strength after curing, which can improve the overall structural strength of the waterproof plywood (100) for formwork.

[0075] Meanwhile, in step (c), among the plurality of veneer layers (110), the veneer layer (110) adjacent to the construction surface direction may be coated with a first coating amount, and the veneer layer (110) placed in the center may be coated with a second coating amount greater than the first coating amount. Since the veneer layer (110) adjacent to the construction surface direction is formed thinly and the interlayer boundary is dense, sufficient bonding strength can be secured with a relatively small amount of adhesive resin, and excessive application of adhesive resin may delay the curing time or increase costs. On the other hand, since the central veneer layer (110) is formed thickly and has a wide contact area, a strong bond can be secured by sufficiently applying the adhesive resin with the second coating amount.

[0076] In this way, by applying different types or amounts of adhesive resin according to the location of the veneer layer (110), the performance required for each location can be optimized and the overall quality and economic efficiency can be improved.

[0077] Next, a functional insert layer may be disposed between a plurality of veneer layers (110) in the present invention. The functional insert layer may be selectively disposed between at least some of the plurality of veneer layers (110) and may perform a role in improving specific performance required for the waterproof plywood (100) for formwork. The functional insert layer may include at least one of a flame retardant impregnated layer, a preservative impregnated layer, or a reinforcing fiber layer.

[0078] The flame retardant impregnated layer may be formed in the form of a sheet or film impregnated with a flame retardant component and may be placed between the veneer layers (110) adjacent to the construction surface direction among the plurality of veneer layers (110). Since the construction surface direction may be exposed to high temperatures or fire hazards in a concrete pouring environment, placing the flame retardant impregnated layer can delay the combustion speed and prevent fire spread in the event of a fire. The flame retardant impregnated layer may be in the form of paper, non-woven fabric, or film impregnated with a flame retardant component such as a phosphorus-based flame retardant, a halogen-based flame retardant, or aluminum hydroxide, and may be laminated together with an adhesive resin between the veneer layers (110) to be integrally bonded.

[0079] The preservative-impregnated layer may be formed in the form of a sheet or film impregnated with a preservative component and may be placed between the outer veneer layers exposed to the outside among the plurality of veneer layers (110). Since the outer veneer layers may be exposed to moisture, mold, pests, etc. during the concrete pouring and curing process, the wood can be prevented from decaying and biologically deteriorating by placing the preservative-impregnated layer. The preservative-impregnated layer may be in the form of paper, non-woven fabric, or film impregnated with a preservative component such as a copper-based preservative, a boron-based preservative, or an insecticide, and may improve the durability of the veneer layer (110).

[0080] The reinforcing fiber layer can be formed in the form of a sheet or fabric made of high-strength fibers such as glass fibers, carbon fibers, or aramid fibers, and can be placed between the veneer layers (110) that are positioned in the central part among the plurality of veneer layers (110). Since the central part is the part that performs the main load-bearing role of the waterproof plywood (100) for formwork, the tensile strength, compressive strength, and bending strength of the waterproof plywood (100) for formwork can be improved by placing the reinforcing fiber layer. The reinforcing fiber layer may be in the form of a unidirectional sheet in which the fibers are oriented in a certain direction, or in the form of a fabric in which the fibers are cross-arranged, and can be laminated together with an adhesive resin between the veneer layers (110) to form a composite structure.

[0081] Additionally, in the present invention, step (d) may include a process of selectively placing a functional insert layer during the process of laminating a plurality of veneer layers (110). In step (d), while laminating the veneer layers (110) sequentially, a flame retardant impregnated layer, a preservative impregnated layer, or a reinforcing fiber layer may be inserted at a specific location. The functional insert layer may be cut to the same size as the veneer layer (110) and placed, and may be bonded together with the veneer layer (110) by the adhesive resin by being inserted between the veneer layers (110) coated with the adhesive resin.

[0082] In this way, by selectively placing a functional insert layer between multiple veneer layers (110), the flame retardancy, durability, and strength of the waterproof plywood (100) for formwork can be selectively improved, and the type and placement location of the functional insert layer can be adjusted according to the usage environment and required performance.

[0083] Next, in the present invention, the waterproof film (120) may be formed as a multilayer structure in which a plurality of layers are laminated. Compared to the case where the waterproof film (120) is formed as a single layer, by being formed as a multilayer structure, water resistance, surface smoothness, and durability can be improved simultaneously.

[0084] Specifically, the waterproof film (120) may include a first film layer bonded to the construction surface of the veneer layer (110) and a second film layer laminated on the outer side of the first film layer. The first film layer may be a film formed by impregnating a paper material with phenol-formaldehyde resin. The phenol-formaldehyde resin has excellent water resistance and heat resistance, so it can secure resistance to moisture and heat generated in a concrete pouring environment, and has excellent bonding strength with the construction surface of the veneer layer (110), so it can prevent the waterproof film (120) from peeling off from the construction surface. The first film layer can be bonded to the construction surface of the veneer layer (110) by a heat-pressing method, and the phenol-formaldehyde resin can be strongly bonded to the construction surface as it hardens by heat.

[0085] The second film layer may be a film formed by impregnating a paper with melamine resin. Melamine resin has high surface hardness and excellent smoothness, which can create a smooth surface on the construction surface when pouring concrete, and can facilitate demolding by reducing adhesion to the concrete. In addition, melamine resin has excellent abrasion resistance, which can prevent damage to the surface of the waterproof film (120) even during repeated demolding operations. The second film layer may be laminated on the outer side of the first film layer by a hot-press method and bonded integrally with the first film layer.

[0086] In this way, by forming the waterproof film (120) into a multilayer structure consisting of a first film layer impregnated with phenol-formaldehyde resin and a second film layer impregnated with melamine resin, excellent water resistance and bonding strength with the veneer layer (110) due to the first film layer, and excellent surface smoothness and demolding due to the second film layer can be simultaneously secured. In addition, the multilayer structure of the waterproof film (120) has a thicker thickness compared to a single-layer structure, so the moisture blocking path is longer, thereby further improving the waterproofing performance of the waterproof plywood (100) for formwork.

[0087] Preferred embodiments according to the present invention have been described above, and it is obvious to those skilled in the art that, in addition to the embodiments described above, the present invention may be embodied in other specific forms without departing from the spirit or scope thereof. Therefore, the embodiments described above should be regarded as illustrative rather than restrictive, and accordingly, the present invention is not limited to the description above but may be modified within the scope of the appended claims and their equivalents. Explanation of the symbols

[0088] 100: Waterproof plywood 110: Veneer layer 120: Waterproof film 130: Waterproof resin

Claims

Claim 1 A plate shape is formed by including a plurality of veneer layers laminated by filling Indonesian rubber wood from which the latex has been removed to a thickness less than or equal to a predetermined standard thickness, wherein the plurality of veneer layers are bonded and compressed by a first adhesive resin or a second adhesive resin, and a waterproof film is attached to the construction surface in contact with the formwork, wherein one or more veneer layers among the plurality of veneer layers adjacent to the direction of the construction surface are formed with a first thickness, and a veneer layer among the plurality of veneer layers disposed in the inner central part of the veneer layer formed with the first thickness is formed with a second thickness greater than the first thickness, wherein the first adhesive resin is applied to the outer veneer layer exposed to the outside among the plurality of veneer layers, and the second adhesive resin is applied to the inner veneer layer disposed inside among the plurality of veneer layers, wherein either the first adhesive resin or the second adhesive resin is applied to the veneer layer formed with the first thickness in a first application amount, and the Waterproof plywood for formwork, wherein either a first adhesive resin or a second adhesive resin is applied in a second application amount that is relatively larger than the first application amount. Claim 2 In claim 1, the plurality of veneer layers are laminated such that the grain direction of each veneer layer is oriented in the same direction, forming a waterproof plywood for formwork. Claim 3 In claim 1, the plurality of veneer layers are interlaced such that the grain directions of adjacent veneer layers are orthogonal to each other, forming a waterproof plywood for formwork. Claim 4 In claim 1, the waterproof film is a waterproof plywood for formwork formed by impregnating a paper material with phenol-formaldehyde resin. Claim 5 In claim 1, a waterproof plywood for formwork having a waterproof film additionally attached to the back surface formed on the opposite side of the construction surface. Claim 6 In claim 1, a waterproof plywood for formwork, wherein a waterproof resin is applied to the perimeter surface of the plurality of veneer layers. Claim 7 (a) preparing Indonesian rubber trees from which the latex has been removed; (b) producing multiple veneer layers by filling the rubber trees to a thickness less than or equal to a predetermined standard thickness; (c) applying a first adhesive resin or a second adhesive resin to the multiple veneer layers; (d) laminating the multiple veneer layers to which the first adhesive resin or the second adhesive resin has been applied; and (e) compressing the multiple veneer layers laminated in step (d) to form a waterproof plywood board in the shape of a plate for formwork. The method comprises: (f) attaching a waterproof film to the construction surface of the waterproof plywood for the formwork that contacts the formwork; wherein step (b) comprises manufacturing one or more veneers adjacent to the direction of the construction surface among the plurality of veneers with a first thickness, and manufacturing a veneer layer positioned in the inner central part of the veneer layer formed with the first thickness with a second thickness greater than the first thickness; and step (c) comprises applying the first adhesive resin to the outer veneer layer exposed to the outside among the plurality of veneers, and applying the second adhesive resin to the inner veneer layer positioned inside among the plurality of veneers, wherein either the first adhesive resin or the second adhesive resin is applied to the veneer layer formed with the first thickness with a first application amount, and either the first adhesive resin or the second adhesive resin is applied to the veneer layer formed with the second thickness with a second application amount that is relatively larger than the first application amount. Waterproof plywood manufacturing method. Claim 8 A method for manufacturing waterproof plywood for formwork, wherein in claim 7, step (f) additionally attaches a waterproof film to the back surface formed opposite to the construction surface. Claim 9 A method for manufacturing a waterproof plywood for formwork according to claim 7, further comprising, after step (f), step (g) of applying a waterproof resin to the periphery of the plurality of veneer layers. Claim 10 A method for manufacturing waterproof plywood for formwork, wherein in claim 9, step (g) involves applying a waterproof resin stepwise in the order of the perimeter surface, the corners where the perimeter surfaces meet, and the vertices where the corners meet.

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