Resin-metal composite and method for manufacturing the same

Abstract

To provide a resin-metal composite and a method for manufacturing the same, which can bond a metal core material to its outer surface and a wood-resin composite material coating layer with a higher adhesive force using a simple method. [Solution] A resin-metal composite comprising a metal core material 10 with a surface treatment and a coating layer 30 made of wood-resin composite material covering the outer surface of the core material 10, wherein the outer surface of the core material 10 is covered with a pseudo-rough surface layer 20 made of water-based resin, the outer surface of the pseudo-rough surface layer 20 is dehydrated by rapid drying of the water-based resin and roughened to an uneven surface, the coating layer 30 made of wood-resin composite material is laminated on the outer surface of the core material 10 via the pseudo-rough surface layer 20, and is fixed by a combination of physical and chemical adhesive action of the pseudo-rough surface layer 20.

Description

Technical Field

[0001] The present invention relates to a resin-metal composite coated with a coating layer made of a synthetic resin mixed with wood powder on the surface of a metal material. More specifically, it relates to a resin-metal composite in which a coating layer made of a synthetic resin is firmly coated on a metal material and a method for manufacturing the same.

Background Art

[0002] Common building materials are made of solid wood. However, solid wood requires maintenance, and even when coated with a weather-resistant film such as paint or varnish as a measure against deterioration caused by weather exposure or the like, the protection period is relatively short.

[0003] In recent years, as an alternative building material to wood, a wood-plastic composite (WPC) manufactured by mixing wood powder (filler) and resin has been used as an interior building material or an exterior building material with excellent design. Since the wood-plastic composite contains a large amount of wood powder, when it is commercialized as a building material, it is heavier than wood, and when it has a hollow structure, it is vulnerable to water and impact, and the wood-plastic composite is prone to breakage.

[0004] In order to solve the strength problem, a coated structure has been proposed in which a cylindrical coating body is formed in advance from a wood-plastic composite and a steel material such as a C-shaped steel or a square steel pipe is inserted into the coating body. This coated structure not only has a high manufacturing cost, but also the operation of inserting the steel material into the coating body is very difficult. Furthermore, since a gap occurs between the coating body and the steel material, when an impact is applied, the coating body is prone to breakage.

[0005] In order to avoid the problems of the coated structure, a resin-metal composite with improved adhesion to the coating has been proposed in Patent Document 1. Patent Document 1 discloses a resin-metal composite in which a coating made of wood-resin composite material is formed on the surface of a thin metal material by applying a primer or plasma treatment to the surface of the metal material, followed by applying a wood-resin composite material containing a coupling agent.

[0006] If a thermosetting resin suitable for adhesion to metal materials (e.g., epoxy resin) is used alone as a primer base material, the adhesion to wood-resin composite materials will be weak. Therefore, as described in Patent Document 1, a mixture of two types of resins is used as a base material: a thermosetting resin suitable for adhesion to metal materials (e.g., epoxy resin, melamine resin) and a thermoplastic resin suitable for adhesion to wood resin composite materials (e.g., methylcellulose, polyvinyl acetate resin).

[0007] In addition, in plasma-based surface treatment of metal materials, the entire surface of the metal material is irradiated with plasma in a pressure-controlled environment filled with plasma gas (argon), thereby physically roughening the surface of the metal material. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 2015-505750 [Patent Document 2] Special Publication No. 2017-510477 [Patent Document 3] Special Publication No. 2012-66403 [Overview of the project] [Problems that the invention aims to solve]

[0009] The resin-metal composite disclosed in Patent Document 1 has the following problems. <1> Because thermosetting resins and thermoplastic resins differ in physical properties, melting conditions, etc., it is technically difficult to mix and use different types of resins. <2> When mixing two types of primer resins, uneven mixing can easily occur depending on the mixing conditions. If the primer is applied with uneven mixing, it can lead to variations in adhesion and cause poor adhesion. <3> When adhesion failure occurs due to the factors described above, the bonded area is prone to peeling due to impact, temperature contraction, etc. during use, ultimately leading to the problem of the surface coating being easily damaged. <4> When using a primer for surface preparation of metal materials, applying a thick layer of primer to avoid poor adhesion increases the cost of surface preparation. <5> When using plasma treatment as a surface treatment method for metal materials, it is necessary to secure a pressure control chamber, and to install plasma gas supply equipment and plasma irradiation equipment for the plasma treatment. Therefore, plasma facilities are large-scale, and the cost of surface treatment for metal materials becomes very high.

[0010] The present invention has been made in view of the above points, and its object is to provide a resin-metal composite and a method for manufacturing the same that can fix the outer surface of a metal core material and a coating layer made of wood-resin composite material with a higher adhesive force by a simple method. [Means for solving the problem]

[0011] The present invention relates to a resin-metal composite comprising a surface-treated metal core and a resin coating layer covering the outer circumferential surface of the core, wherein the outer circumferential surface of the core is covered with a pseudo-roughened surface layer made of an aqueous resin, the outer circumferential surface of the pseudo-roughened surface layer is dehydrated by rapid drying of the aqueous resin and thus roughened to an uneven surface, the coating layer is laminated to the outer circumferential surface of the core via the pseudo-roughened surface layer, and the coating layer is integrally fixed to the outer circumferential surface of the core by a combination of physical adhesion through the uneven surface of the pseudo-roughened surface layer and chemical adhesion between the resins of the pseudo-roughened surface layer and the coating layer. In another embodiment of the present invention, the aqueous resin is an aqueous dispersion or an aqueous emulsion. In another embodiment of the present invention, the coating layer is composed of a wood-resin composite material which is a mixture of wood powder and resin. The present invention relates to a method for manufacturing a resin-metal composite in which a metal core material is subjected to an uneven surface treatment and the outer surface of the core material is covered with a resin coating layer, comprising: an aqueous resin coating step of applying an aqueous resin to the surface of the core material; a core material surface treatment step of rapidly drying the aqueous resin to form an uneven pseudo-rough surface layer on the outer surface of the core material; a coating layer coating step of covering the outer surface of the core material via the pseudo-rough surface layer to form a resin-metal composite; and a cooling step of cooling the resin-metal composite, wherein the coating layer is integrally fixed to the outer surface of the core material by combining a physical adhesive action via the uneven surface of the pseudo-rough surface layer and a chemical adhesive action between the resins of the pseudo-rough surface layer and the coating layer. In another embodiment of the present invention, in the surface processing step of the core material, the means for rapidly drying the aqueous resin is one of a high-frequency induction heating device, a dielectric heating device, a hot air circulation furnace, or an infrared heating furnace. In another embodiment of the present invention, in the coating step of the coating layer, a mold is used to coat the outer surface of the core material with a coating layer made of wood-resin composite material via a pseudo-roughened layer. In another embodiment of the present invention, the aqueous resin may be an aqueous dispersion or an aqueous emulsion. In another embodiment of the present invention, the coating layer is composed of a wood-resin composite material which is a mixture of wood powder and resin. [Effects of the Invention]

[0012] The present invention provides at least one of the following effects. <1> In this invention, a coating layer is fixed to the outer surface of a metal core material by combining a physical fixing action that utilizes the uneven shape of a pseudo-roughened surface layer made of water-based resin formed on the outer surface of the metal core material, and a chemical fixing action that utilizes the resin components of the pseudo-roughened surface layer. Therefore, compared to conventional chemical surface preparation methods that involve applying a primer to the outer surface of the metal core, or conventional physical surface preparation methods that involve roughening the outer surface of the metal core by creating irregularities, the bonding strength between the metal core and the coating layer is significantly improved. <2>Since the adhesion strength between the core material and the coating layer is significantly improved, the durability of the coating layer against external impact forces, temperature shrinkage, etc. is higher than that of the prior art. <3>The pseudo-rough layer can be formed using an aqueous resin. This not only eliminates the need for the cumbersome primer treatment that combines different types of resins as in the prior art, but also resolves the problems of uneven resin mixing and variations in adhesion caused by such uneven mixing. <4>In the present invention, by simply rapidly drying the aqueous resin applied to the outer peripheral surface of the metal core material to form a pseudo-rough layer, a pseudo-concave-convex surface can be economically formed on the flat outer peripheral surface of the core material. Therefore, a large-scale plasma treatment facility is not required for the surface treatment of the metal core material.

Brief Description of the Drawings

[0013] [Figure 1] Perspective view of the resin-metal composite according to the present invention, with a part broken [Figure 2] Explanatory drawing of the manufacturing method of the resin-metal composite according to the present invention <E [Figure 3] Cross-sectional model diagram of the resin-metal composite in each manufacturing process of the resin-metal composite [Figure 4A] Model diagram of the pseudo-rough layer [Figure 4B] Microscopic photograph of the pseudo-rough layer

Modes for Carrying Out the Invention

[0014] The present invention will be described in detail below with reference to the drawings.

[0015] <1>Overview of the resin-metal composite The resin-metal composite according to the present invention includes a metal core material 10, a pseudo-rough layer 20 integrally formed on the smooth outer peripheral surface (surface) of the core material 10, and a coating layer 30 made of a wood plastic composite (WPC) that covers the surface of the pseudo-rough layer 20. That is, in the present invention, the pseudo-rough layer 20 and the coating layer 30 are sequentially integrated and laminated on the surface of the core material 10.

[0016] <2> metal core The metal core material 10 is a strength component of a resin-metal composite and is made of a metal material.

[0017] <2.1> Examples of metal materials As the material for the metal core 10, known metal materials such as aluminum, stainless steel, iron, titanium alloy, zinc alloy, and brass can be used, and the metal material is appropriately selected depending on the intended use of the resin-metal composite. When using resin-metal composites as interior or exterior building materials, aluminum is a suitable metal material due to its lightweight nature, durability, and excellent workability.

[0018] <2.2>Cross-sectional shape of the core material The cross-sectional shape of the core material 10 can be appropriately selected depending on the intended use of the resin-metal composite. The specific cross-sectional shape of the core material 10 can be any of the following forms: cylindrical or rod-shaped (with a circular, elliptical, polygonal cross-section, etc.), L-shaped or U-shaped, or plate-shaped. In this example, we will describe the form of a hollow cylindrical body in which the cross-section of the core material 10 is rectangular.

[0019] <3> Pseudo-roughened layer The pseudo-roughened surface layer 20 is a water-based resin-based roughened surface layer located between the core material 10 and the coating layer 30, and exhibits suitable adhesion to the core material 10 and the coating layer 30. In the present invention, the aqueous resin layer is transformed into an uneven, pseudo-rough surface layer 20 by rapidly drying the aqueous resin applied to the outer surface of the core material 10 to forcibly dehydrate the aqueous resin.

[0020] <3.1>Aqueous resin Water-based resins are preferably in the form of water-based dispersions or water-based emulsions.

[0021] <4> Covering layer In this invention, the entire outer surface or a portion of the outer surface of the core material 10 is covered with a coating layer 30 via a pseudo-roughened surface layer 20 and fixed integrally. The coating layer 30 is composed of a known wood-plastic composite material (WPC), which is a mixture of wood powder (filler) and resin. The wood powder may be one or a mixture of either organic wood powder (wood powder, wood pellets, wood fibers, etc.) or inorganic filler (talc, calcium carbonate, wollastonite, or kaolinite, etc.).

[0022] [Manufacturing method] Next, the manufacturing method of the resin-metal composite will be explained in detail with reference to Figures 2 and 3. The resin-metal composite is manufactured through the following processes: "surface processing (S10)", "coating layer application (S20)", and "cooling process (S30)". When manufacturing a resin-metal composite on a production line, the core material 10 is preferably transported sequentially to each process via a known feeding device.

[0023] <1> Preparation of core material Prepare core materials 10 with various cross-sectional shapes. In this example, we will describe the form of a hollow cylindrical body in which the cross-section of the core material 10 is rectangular. The metal core material 10 is supplied to the surface processing process via the feeding device 40. The metal core material 10 is used with a smooth outer surface, without roughening it.

[0024] <2> Surface finishing process for the core material (S10) In this invention, the core material 10 is surface-treated by applying an aqueous resin to its outer surface and then rapidly drying the applied aqueous resin. <2.1> Application of water-based resins A water-based resin solution is applied to the outer surface of the metal core material 10 to form a coating.

[0025] <2.1.1> Thickness of the water-based resin coating The coating thickness of the water-based resin film should be appropriately selected depending on the intended use of the resin-metal composite.

[0026] <2.1.2>Means (apparatus) for applying water-based resins The coating apparatus 50 for the water-based resin can be used for application by spraying, using a coating roller, or a brush. In practice, the coating apparatus 50 can be operated using a known spraying method. By using a spray-type coating device 50, the water-based resin can be uniformly applied to the entire outer surface of the core material 10.

[0027] After the water-based resin coating process is complete, the core material 10 is supplied to the surface finishing process.

[0028] <2.2> Rapid drying (formation of a pseudo-roughened surface layer) Next, the water-based resin is rapidly heated and dehydrated using the quick-drying device 60, thereby transforming the water-based resin layer applied to the outer surface of the core material 10 into a pseudo-rough surface layer 20.

[0029] <2.2.1> Purpose of rapid drying The purpose of rapid drying is not to shorten the curing time of the water-based resin, but to evaporate the water contained in the water-based resin and form a pseudo-roughened surface layer 20. By forming a pseudo-roughened surface layer 20 on the flat outer surface of the core material 10, the outer surface of the core material 10 is formed as a pseudo-uneven surface. By simply rapidly drying the water-based resin, there is no need to directly perform physical surface roughening on the outer surface of the core material 10.

[0030] Thus, in this invention, a pseudo-roughened surface can be formed on the outer surface of the core material 10 simply by rapidly drying an aqueous resin applied to the outer surface of the core material 10, thereby forming a pseudo-roughened layer 20 on the outer surface of the core material 10. Therefore, it is not necessary to directly roughen the outer surface of the core material 10 using physical surface roughening methods such as plasma processing or shot blasting.

[0031] <2.2.2>Methods for rapid drying by heating (rapid drying device) Simply allowing a water-based resin to air dry for a long period of time makes it difficult to mold it into a rough surface. As a result of diligent research, this invention has discovered that a water-based resin layer can be roughened by rapidly drying it and forcibly dewatering it in a short period of time.

[0032] As the rapid drying device 50, which is a means for rapidly drying the aqueous resin layer, conventionally known heating means such as a high-frequency induction heating device, a dielectric heating device, a hot air circulation furnace, or an infrared heating furnace can be used. Since the energy efficiency of infrared heating is around 30%, while that of high-frequency induction heating is 70% or more, a high-frequency induction heating device is preferable.

[0033] When rapidly drying water-based resins using a high-frequency induction heating device, the frequency and heating time should be appropriately selected considering the coating thickness of the water-based resin.

[0034] <2.2.3> Structure of the pseudo-roughened layer Figures 4A and 4B show micrographs of the surface of the pseudo-roughened layer 20. As can be seen in the microscopic image, crack-like deep grooves 21 exhibiting a tortoise-shell pattern are formed on the surface of the pseudo-roughened layer 20. The deep grooves 21 are formed by the rapid drying of the water-based resin, which causes the water-based resin to shrink.

[0035] <2.2.4> Heating temperature and heating time When using a high-frequency induction heating device, the frequency (heating temperature) and heating time should be appropriately selected considering the components and thickness of the water-based resin.

[0036] <2.2.5> Adhesion between the core material and the pseudo-roughened layer The water-based resin adheres to the outer surface of the core material 10 due to its self-adhesive properties. However, since the pseudo-roughened layer 20 is formed by the alteration of the water-based resin attached to the outer surface of the core material 10, the adhesion between the outer surface of the core material 10 and the back surface of the pseudo-roughened layer 20 is enhanced. Once the surface treatment of the core material 10 is complete, the core material 10 is supplied to the coating process for the coating layer.

[0037] <3> Coating process for the coating layer (S20) A coating layer 30 made of wood-plastic composite material (WPC) is formed on the surface of the core material 10, which is covered with a pseudo-roughened layer 20.

[0038] <3.1> Thickness of the coating layer The thickness of the coating layer 30 is selected appropriately depending on the intended use of the resin-metal composite.

[0039] <3.2>Means for forming a coating layer For example, a coating layer 30 can be applied to the surface of the pseudo-roughened layer 20 using a mold 60 and an extrusion device 61. The mold 60 has a structure that allows the core material 10 to be inserted through it, and an extrusion device 61 is integrally assembled to a part of the mold 60, so that the wood-resin composite material can be extruded into the mold 60 in a molten state through the extrusion device 61.

[0040] <3.3> Method for forming a coating layer While supplying the core material 10 with a pseudo-roughened surface layer 20 formed inside the mold 60, the wood-resin composite material is started to be supplied into the mold 60 in a molten state through the extrusion device 61. The discharge volume and discharge pressure of the wood-resin composite material are appropriately selected considering the supply speed of the core material 10 and the thickness of the coating layer 30.

[0041] Inside the mold 60, a wood-resin composite material is applied to the outer surface of the pseudo-roughened layer 20 to form a coating layer 30 of a predetermined thickness. As previously described, the coating layer 30 adheres firmly to the outer surface of the core material 10 via the pseudo-roughened surface layer 20.

[0042] <3.4> Adhesion strength (bonding strength) between the pseudo-roughened surface layer and the coating layer Figure 3 shows an enlarged view of the cross-section of the pseudo-roughened layer 20. In addition to the formation of deep grooves 21 in a tortoise-shell pattern on the pseudo-roughened layer 20, minute uneven surfaces 22 are formed on the surface of the pseudo-roughened layer 20 as traces of water evaporation.

[0043] The outer surface of the core material 10 is formed as an uneven surface via the pseudo-roughened surface layer 20. Therefore, the coating layer 30 penetrates into the deep grooves 21 and uneven surfaces 22 of the pseudo-roughened layer 20, exerting an anchoring effect, thus physically fixing the pseudo-roughened layer 20 and the coating layer 30 together. Furthermore, the aqueous resin component constituting the pseudo-roughened surface layer 20 and the resin component constituting the coating layer 30 react and fuse together, thereby chemically fixing the space between the pseudo-roughened surface layer 20 and the coating layer 30. Thus, in this invention, since both physical and chemical fastening means exert their fastening functions simultaneously, the pseudo-roughened layer 20 and the coating layer 30 can be firmly fixed together. Therefore, in the present invention, the bonding strength between the metal core material 10 and the coating layer 30 made of wood resin composite material is significantly improved compared to conventional chemical surface treatment methods that involve applying a primer to the outer surface of the metal core material 10, or conventional physical surface treatment methods that involve roughening the outer surface of the metal core material 10 by creating an uneven surface.

[0044] In particular, since the bonding area due to the chemical bonding surface is formed and increased along the outer circumferential surface of the deep groove 21 and the uneven surface 22, a greater bonding force can be achieved compared to when the bonding is performed in a form where the deep groove 21 and uneven surface 22 do not exist.

[0045] <4> Cooling process (S30) The resin-metal composite fabricated by covering the outer surface of the pseudo-roughened layer 20 with a coating layer 30 is cooled. The cooling device 70 may be either an air cooling means (forced air cooling) or a water cooling means (submersion cooling). The cooling process is not limited to forced cooling using the cooling device 70; natural cooling can also be applied. [Explanation of symbols]

[0046] 10. Metal core material 20. Water-based resin-based pseudo-rough surface layer 20a...Water-based resin 21...deep groove 22...Uneven surface 30...Coating layer 40.. Coating device 50...Quick drying device 60... Mold 61.. Extrusion device 70...Cooling device

Claims

1. A resin-metal composite comprising a metal core material with a surface treatment and a resin coating layer covering the outer surface of the core material, The outer surface of the core material is covered with a pseudo-roughened layer made of a water-based resin. The outer surface of the aforementioned pseudo-roughened layer is dehydrated by rapid drying of the aqueous resin and then roughened to an uneven surface. A coating layer is laminated on the outer surface of the core material via the aforementioned pseudo-roughened layer. The coating layer is integrally fixed to the outer surface of the core material by a combination of physical adhesion through the uneven surface of the pseudo-roughened layer and chemical adhesion between the resins of the pseudo-roughened layer and the coating layer. Resin metal composite.

2. The resin-metal composite according to claim 1, characterized in that the aqueous resin is an aqueous dispersion or an aqueous emulsion.

3. The resin-metal composite according to claim 1, characterized in that the coating layer is composed of a wood-resin composite material which is a mixture of wood powder and resin.

4. A method for manufacturing a resin-metal composite, wherein the outer surface of a metal core is subjected to an uneven surface treatment, and the outer surface of the core is covered with a resin coating layer, A step of applying an aqueous resin to the surface of the core material, A core material surface processing step, in which the aqueous resin is rapidly dried to form a pseudo-roughened surface layer exhibiting an uneven shape on the outer surface of the core material, A coating step to form a resin-metal composite by coating the outer surface of the core material with a coating layer via the aforementioned pseudo-roughened surface layer, The process includes a cooling step for cooling the resin-metal composite, The coating layer is integrally fixed to the outer surface of the core material by using both a physical adhesive action through the uneven surface of the pseudo-roughened layer and a chemical adhesive action between the resins of the pseudo-roughened layer and the coating layer. A method for manufacturing resin-metal composites.

5. The method for manufacturing a resin-metal composite according to claim 4, characterized in that, in the surface processing step of the core material, the means for rapidly drying the aqueous resin is one of a high-frequency induction heating device, a dielectric heating device, a hot air circulation furnace, or an infrared heating furnace.

6. The method for manufacturing a resin-metal composite according to claim 4, characterized in that, in the coating step of the coating layer, a mold is used to coat the outer surface of the core material with a coating layer made of wood-resin composite material via a pseudo-roughened surface layer.

7. The method for producing a resin-metal composite according to claim 4, characterized in that the aqueous resin is an aqueous dispersion or an aqueous emulsion.

8. The method for producing a resin-metal composite according to claim 4, characterized in that the coating layer is a wood-resin composite material which is a mixture of wood powder and resin.

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