Panel for concrete formwork and manufacturing method thereof

Abstract

A panel for a concrete formwork comprises a polymer core material (1) and a reinforcing layer (2) on at least one side of the core material (1). The reinforcing layer (2) comprises woven glass fibers. The core material (1) comprises a thermosetting polymer waste material, a glass fiber filler and a thermosetting resin, wherein the glass fiber filler is a glass fiber filler existing in the thermosetting polymer waste material and / or a glass fiber filler independent of the thermosetting polymer waste material. The invention also relates to a manufacturing method of the panel (such as the panel).

Description

Technical Field

[0001] The invention relates to a panel for a concrete formwork and a manufacturing method thereof. Background Art

[0002] Panels for concrete formworks generally comprise a wood core material which gives them very good mechanical characteristics at a competitive price. Panels having the same characteristics as the general panels with a wood core material are also known, which comprise a polymer core material and a reinforcement layer on at least one side of the core material.

[0003] EP1635010A1 discloses a panel for a concrete formwork, the panel comprising a polymer core and an optional layer on at least one face of the core. The polymer core comprises thermoplastic waste, in particular recycled polypropylene, combined with rubber waste. Summary of the invention

[0004] The object of the present invention is to provide a panel for a concrete formwork and a method for manufacturing the same as defined in the claims.

[0005] A first aspect of the present invention relates to a panel for a concrete formwork, the panel comprising a polymer core material and a reinforcing layer on at least one side of the core material. The reinforcing layer comprises woven glass fibers. The core material comprises thermosetting polymer waste, glass fiber filler and thermosetting resin, wherein the glass fiber filler is a glass fiber filler present in the thermosetting polymer waste and / or a glass fiber filler independent of the thermosetting polymer waste.

[0006] A second aspect of the invention relates to a method of manufacturing a structural panel, such as the panel described above, comprising the following steps:

[0007] a. Grinding thermosetting polymer waste;

[0008] b. mixing a thermosetting resin and a glass fiber filler separate from the thermosetting polymer waste with the ground thermosetting polymer waste; and

[0009] c. curing the thermosetting resin so that it acts as a binder for the ground thermosetting polymer waste and glass fiber filler to form a mixture, thereby obtaining the panel.

[0010] With the panel of the invention, an alternative to panels for concrete formwork with a wood core and to panels with a thermoplastic waste core is obtained. The panel of the invention meets the required mechanical characteristics and enables the use of thermosetting polymer waste that is difficult to recycle and highly polluting.

[0011] These and other advantages and features of the present invention will become apparent from the accompanying drawings and detailed description of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a cross-sectional elevation view of a panel according to a preferred embodiment of the present invention.

[0013] Figure 2 is a cross-sectional elevation view of a panel according to a second embodiment of the present invention in a horizontal concrete form. DETAILED DESCRIPTION

[0014] The concrete formwork panels 10 and 10' of the present invention include a polymer core material 1 and a reinforcing layer 2 on at least one side of the core material 1. Figure 1 and 2 As shown. The reinforcement layer 2 comprises woven glass fibers, and the core material 1 comprises thermosetting polymer waste, glass fiber filler and thermosetting resin, wherein the glass fiber filler is a glass fiber filler existing in the thermosetting polymer waste and / or a glass fiber filler independent of the thermosetting polymer waste. In other words, the glass fiber filler in the core material 1 is the sum of the glass fiber filler existing in the thermosetting polymer waste and / or the glass fiber filler added to the thermosetting polymer waste during the manufacturing method of the panel.

[0015] In those cases where all the glass fiber fillers are present in the thermosetting polymer waste, it is avoided that other glass fiber fillers independent of the thermosetting polymer waste must be added to the thermosetting polymer waste, thereby reducing the raw material cost. In those cases where the glass fiber fillers in the thermosetting polymer waste are residual, all the glass fiber fillers of the core material must be added separately, except that they are independent of the thermosetting polymer waste. However, in most cases, a part of them is already present in the thermosetting polymer waste, and another part will have to be added separately. The percentage of glass fiber fillers and thermosetting polymer waste that must be added will depend on the type of starting thermosetting polymer waste.

[0016] The core material 1 comprises thermosetting polymer waste, instead of thermoplastic waste. In fact, thermosetting polymer waste preferably comprises the majority weight percentage of the main compound of the core material.

[0017] Thermosetting polymer materials are processed by heat curing (where polymer bonds are formed) to achieve rigidity. Thermosetting polymer waste is waste, residual or leftover thermosetting polymer material that is discarded because it has cured and cannot be reheated and shaped because it degrades, unlike thermoplastic waste, which can be reshaped and heated as many times as needed. Therefore, while thermosetting polymer waste contributes to pollution like all polymer waste, it is more difficult to recycle or reuse at a competitive cost because it takes generations to decompose.

[0018] In order to be able to reuse the thermosetting polymer waste, the ground thermosetting waste is mixed with a thermosetting resin. Despite the fact that the thermosetting polymer waste may contain a thermosetting resin, the thermosetting resin of the waste is ineffective because it is in a cured or semi-cured state, wherein the panel of the present invention requires a thermosetting resin that is not pre-cured to be able to act as a binder for the thermosetting polymer waste. Therefore, when forming the core material, the thermosetting resin of the core material acts as a binder for the ground thermosetting polymer waste and the glass fiber filler.

[0019] The concrete formwork panel of the present invention meets the mechanical characteristics required for formwork applications, such as a flexural strength of at least 30 MPa and a flexural modulus of at least 3500 MPa. The mechanical characteristics in the panel of the present invention are achieved in particular due to the glass fiber filler of the core material and the woven glass fibers of the reinforcement layer.

[0020] Glass fiber fillers are formed of glass fibers that are chopped and dispersed in the core material. In contrast, in woven glass fibers, glass fibers are interwoven with each other to form a single-layer bi-directional glass fiber fabric or multiple layers of three-dimensional glass fiber fabric. Although glass fibers improve mechanical characteristics compared to other fibers at a relatively competitive price, woven glass fibers provide better mechanical characteristics than chopped glass fibers.

[0021] With the panel of the invention, an alternative to panels for concrete formwork with a wood core and to panels with a thermoplastic waste core is obtained. The panel of the invention meets the required mechanical characteristics and enables the use of thermosetting polymer waste that is difficult to recycle and highly polluting.

[0022] exist Figure 1 In the first embodiment shown, the board 10 comprises a reinforcement layer 2 on each side of a core material 1, forming a sandwich type panel. A panel with better mechanical characteristics is thereby achieved, which is easier to manufacture due to the symmetrical construction which traps the ground thermosetting polymer waste of the core material between the reinforcement layers.

[0023] The weight percentage of the thermosetting resin may be 5% to 15% of the weight of the core material 1 .

[0024] Thermosetting polymer waste preferably comprises epoxy resin and / or melamine waste. In other embodiments, the thermosetting polymer waste may comprise phenolic, urea or polyester waste, or a combination of said wastes.

[0025] The total glass fiber filler in the core material 1 is at least 30%, preferably 40% by weight of the core material 1. The higher the weight percentage of glass fiber filler, the better the mechanical characteristics obtained in the panel.

[0026] The glass fiber filler can be chopped glass fiber yarns with a length of 5 mm to 35 mm, preferably 10 mm to 15 mm. Within the glass fiber length range, a compromise needs to be found between good mechanical properties and production difficulty so that the glass fibers can be well impregnated and dispersed.

[0027] The thermosetting resin is preferably a phenolic resin, which has very high cost competitiveness. The thermosetting resin may also be a melamine resin or a combination of a phenolic resin and a melamine resin.

[0028] The woven glass fibers of the reinforcement layer 2 may be pre-impregnated in a thermosetting resin of the same type as the thermosetting resin of the core material 1. Fibers pre-impregnated in a resin are also referred to as prepregs. This enables the joining of the core material 1 and the reinforcement layer 2 to be formed in a single forming process, and a panel having very good adhesion is obtained. In the joining forming step for forming the core material 1 and the reinforcement layer 2, the thermosetting resin of the reinforcement layer 2, on the one hand, serves as a binder for the woven glass fibers, and on the other hand, flows into the core material 1 and cures simultaneously with the thermosetting resin of the core material 1, and since both are the same type of resin, the core material 1 and the reinforcement layer 2 are chemically bonded to each other.

[0029] Preferably, the woven glass fibers of the reinforcement layer 2 are polymer molding compounds supplied in the form of glass fiber reinforced sheet material (also called GF-SMC) or glass fiber sheet molding compounds.

[0030] The basis weight of the reinforcement layer 2 may be 60 to 1200 g / m 2 , preferably 60 to 200 g / m 2 Although better mechanical characteristics in the panel are obtained with a higher basis weight of the reinforcing layer 2, 60 to 200 g / m 2 The basis weight of 200 μm enables the desired mechanical characteristics to be obtained, and the reinforcement layer 2 can be formed together with the core material 1 in a single forming step without the need for additional equipment for a second or third forming step.

[0031] exist Figure 2 In the second embodiment shown, in addition to the above features, the panel 10' further comprises a facing layer 3 on at least one reinforcement layer 2, the reinforcement layer 2 being the reinforcement surface in contact with the cast concrete H, the facing layer 3 comprising melamine resin and aluminum oxide particles. The aluminum oxide is preferably corundum. Therefore, the panel 10' comprises a non-slip smooth finishing surface with excellent wear resistance on the surface in contact with the cast concrete. The facing layer is particularly advantageous in the panel for concrete formwork.

[0032] When the core material 1 and the reinforcement layer 2 are formed in a single forming cycle, the basis weight of the reinforcement layer 2 for achieving the desired mechanical characteristics can be limited, because too high a basis weight of the reinforcement layer 2 may hinder the proper curing of the thermosetting resin of the core material 1. Therefore, the facing layer 3 preferably includes a woven glass fiber mesh or a plurality of woven glass fiber meshes. Thus, the facing layer 3 provides part of the mechanical characteristics for the panel 10', so that the basis weight of the reinforcement layer 2 can be reduced to achieve specific mechanical characteristics, or better mechanical characteristics can be achieved by maintaining the basis weight of the reinforcement layer 2.

[0033] Preferably, the basis weight of the woven glass fiber mesh of the facing layer 3 is equal to or less than 200 g / m 2 Therefore, the woven glass fiber mesh can be well impregnated in the melamine resin and can therefore be well adhered to the facing layer 2 and provide good bending strength.

[0034] Preferably, the woven glass fiber mesh or meshes are arranged away from the surface in contact with the poured concrete H. Therefore, it does not affect the properties required of the surface in contact with concrete, such as smooth surface finish, good wear resistance and chemical resistance.

[0035] Table 1 below shows the values ​​of flexural modulus and flexural strength obtained in a test using a pair of example panels 10 (Sample 1 and Sample 2) according to the present invention.

[0036] Table 1

[0037]

[0038] A second aspect of the present invention relates to a method for manufacturing a panel (such as the above-mentioned panels 10 and 10'), the method comprising the following steps:

[0039] a. Grinding thermosetting polymer waste;

[0040] b. mixing a thermosetting resin and a glass fiber filler separate from the thermosetting polymer waste with the ground thermosetting polymer waste; and

[0041] c. curing the thermosetting resin so that it acts as a binder for the ground thermosetting polymer waste and glass fiber filler to form a mixture, thereby obtaining the panel.

[0042] Preferably, the mixture is placed on the reinforcement layer 2 before forming the mixture, wherein the core material 1 is formed together with the reinforcement layer 2. Therefore, a single forming step is required to form the core material and the reinforcement layer, and better adhesion is obtained between the core material and the reinforcement layer to avoid delamination problems during use.

[0043] Furthermore, an additional reinforcement layer 2 may be placed on the mix before forming the mix, wherein the core material 1 is formed together with the two reinforcement layers 2 in order to produce a sandwich type panel.

[0044] The method may comprise an additional forming step, in which a facing layer 3 is formed; and an attaching step after the additional forming step, in which the facing layer 3 is attached to at least one reinforcement layer 2 by cold adhesion, in order to manufacture a panel comprising the facing layer.

[0045] Preferably, constant temperature and pressure are applied during the forming step.

[0046] Although panels for formwork have been specifically described, the panels of the present invention may also be used in other building applications, such as in structural framing, baseboards, wall panels, ceilings and floors, or in any other application in construction where a structural panel is required.

[0047] Features and / or aspects described for the panel are also applicable to the manufacturing method and vice versa.

Claims

1. A panel for a concrete formwork, comprising a polymer core material (1) and a reinforcing layer (2) on at least one side of the core material (1), characterized in that The reinforcing layer (2) comprises woven glass fibers, and the core material (1) comprises thermosetting polymer waste, thermosetting resin and glass fiber filler, wherein the glass fiber filler is a glass fiber filler present in the thermosetting polymer waste and / or a glass fiber filler independent of the thermosetting polymer waste.

2. A panel as claimed in claim 1, comprising a reinforcement layer (2) on each side of the core material (1), forming a sandwich type panel.

3. A panel as claimed in any preceding claim, wherein the thermosetting polymer waste comprises epoxy resin and / or melamine waste.

4. A panel as claimed in any preceding claim, wherein the glass fibre filler is chopped glass fibre yarns having a length of from 5mm to 35mm, preferably from 10mm to 15mm.

5. The panel according to any one of the preceding claims, wherein the weight percentage of the thermosetting resin is 5% to 15% of the weight of the core material (1).

6. The panel according to any one of the preceding claims, wherein the weight percentage of the total glass fiber filler in the core material (1) is at least 30%, preferably 40%, of the weight of the core material (1).

7. A panel as claimed in any preceding claim, wherein the thermosetting resin is a phenolic resin.

8. A panel as claimed in any one of the preceding claims, wherein the woven glass fibres of the reinforcement layer (2) are pre-impregnated in a thermosetting resin, the thermosetting resin being of the same type as the thermosetting resin of the core material (1), and the woven glass fibres of the reinforcement layer (2) are preferably a polymer moulding compound supplied in the form of a glass fibre reinforced sheet.

9. The panel according to any one of the preceding claims, wherein the reinforcement layer (2) has a basis weight of 60 to 1200 g / m 2 , preferably 60 to 200 g / m 2 .

10. The panel according to any one of the preceding claims, comprising a facing layer (3) on at least one reinforcement layer (2), said facing layer (3) comprising melamine resin and aluminium oxide particles.

11. The panel according to claim 10, wherein the facing layer (3) comprises a woven glass fiber mesh or a plurality of woven glass fiber meshes.

12. The panel according to claim 11, wherein the basis weight of the woven glass fiber mesh of the facing layer (3) is equal to or less than 200 g / m 2 .

13. A method for manufacturing a panel as claimed in any one of the preceding claims, comprising the steps of: - grinding said thermosetting polymer waste; - mixing the thermosetting resin and a glass fiber filler separate from the thermosetting polymer waste with the ground thermosetting polymer waste; and - Curing the thermosetting resin so that it acts as a binder for the ground thermosetting polymer waste and glass fiber filler to form a mixture, thereby obtaining the panel.

14. The manufacturing method according to claim 13, wherein before forming the mixture, the mixture is placed on the reinforcement layer (2), and the core material (1) is formed together with the reinforcement layer (2).

15. The manufacturing method according to claim 13 or 14, wherein constant temperature and pressure are applied in the forming step.

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