WO2005021916A1

WO2005021916A1 - Composite material structure produced by co-extrusion without using adhesive and method of making the same

Info

Publication number: WO2005021916A1
Application number: PCT/KR2004/002116
Authority: WO
Inventors: Do-Young Lee; Yu Huh; Heung-Gyu Lim; Sung-Gye Kim
Original assignee: Lg Chem. Ltd.
Priority date: 2003-08-27
Filing date: 2004-08-23
Publication date: 2005-03-10
Also published as: KR200340251Y1; CN1597300A; CN100503208C

Abstract

Disclosed herein is a composite material structure comprising a metal core having an uneven and grooved outer face, and a synthetic resin, wherein the composite material structure is produced by co-extruding the metal core and the synthetic resin in in-line mode, thereby satisfying the required structural strength, eliminating the need of an adhesive, improving the workability, lessening post-processing steps, and expressing various desired colors. Conventional composite material structures can enhance the adhesion and prevent peeling between different materials by applying an adhesive upon co-extrusion of the materials. In contrast, the claimed composite material structure can prevent peeling between different materials by structurally designing the outer face of the metal core so as to have serrations, and co-extruding the materials without the use of an adhesive. The synthetic resin allows the claimed composite material structure to exhibit superior durability and weather resistance, and to express various desired colors. The inner metal core, such as aluminum, co-extruded in in-line mode, together with the synthetic resin, allows the claimed composite material structure to satisfy the required structural strength.

Description

Description COMPOSITE MATERIAL STRUCTURE PRODUCED BY CO-EXTRUSION WITHOUT USING ADHESIVE AND METHOD OF MAKING THE SAME Technical Field

[1] The present invention relates to a composite material stricture produced by co- extruding a metal core and a synthetic resin in in-line mode, and more particularly to a composite material stricture comprising a metal core having an uneven and grooved outer face, and a synthetic resin, wherein the composite material structure is prodiced by co-extruding the metal core and the synthetic resin in in-line mode, thereby satisfying the required strictural strength, eliminating the need of an adhesive, improving the workability, lessening post-processing steps, and expressing various desired colors. Background Art

[2] The term 'composite material' refers to a material wherein two or more different raw materials are combined to form a physically and chemically new phase. The composite material has more effective functions than the raw materials.

[3] Glass fiber reinforced plastic is the first modern composite material, and has been used since the early 1940s. The concept of the reinforced plastic has been further extended to the fields of metals and ceramics, due to the appearance of carbon fiber having superior properties to glass fiber in the 1960s, and development into metals and ceramics as well as plastics led to the creation of the comprehensive term 'composite material'.

[4] Composite materials are divided into fibrous composite materials and particulate composite materials, depending on the stricture of reinforcements . In addition, composite materials are divided into polymer matrix composite materials, metal matrix composite materials and ceramic matrix composite materials, depending on the kind of matrices to be reinforced.

[5] Of these composite materials, fiber reinforced plastics (FRPs) combining the concept of fiber reinforcement and polymer matrix play a pivotal roll in modern composite materials. FRP is often compared to reinforced concrete.

[6] Assuming that the strength of a polymer matrix is 1, the strength of a glass fiber and a carbon fiber is between 25 and 40. The glass and carbon fibers have a higher stiffness of 20 times and 70 times, respectively, than the polymer matrix. That is, glass and carbon fibers have physical properties superior or comparable to steel, but are lighter in weight than metals. For these reasons, FRP combined with a lighter polymer matrix is an 'ideal lightweight strictural material' which is stronger than steel and lighter than aluminum. Glass fiber reinforced plastics GFRPs) and carbon fiber reinforced plastics (CFRPs), as representative fiber reinforced plastics, are used as essential strictural materials of sporting goods, sich as tennis rackets and golf clubs, ships, express railways, aircrafts, and the like.

[7] In order to obtain light weight and high strength, carbon fibers, silicon carbide fibers, alumina fibers and the like are employed as reinforcing fibers in composite materials using metal or ceramic as a matrix. Such composite materials are used for special applications, e.g., high temperature conditions, where conventional polymer matrix composite materials cannot be applied.

[8] Since conventional windows frames are made of a single material selected from aluminum, synthetic resins and wood, they have many problems. Specifically, aluminum-made window frames have problems in terms of an inflexible opening/ closing operation, limited corrosion resistance, air-tightness, sound- proofness, and heat nsulation. Although window frames made of synthetic resins do not have the above-mentioned problems, instead, they have poor structural strength, high heat susceptibility, and severe compression and expansion due to their high coefficient of linear expansion, compared to the aluminum made window frames. In addition, the burial of a reinforcing steel in a hollow is required to enhance the strictural strength of the synthetic resin-made window frames. F wever, this burial process is very troublesome and complicated, causing poor workability and productivity.

[9] In order to solve these problems of the single material made window frames, composite material window frames consisting of two or more raw materials have been developed.

[10] According to conventional PVC-made window frames, a metal core, such as steel or aluminum, is inserted into PVC during a post-processing step in order to enhance poor structural strength of the PVC-made window frames. Fbwever, uniform quality maintenance is not ensured due to problems caused during post-processing and insertion steps.

[11] Korean Patent Laidopen No. 1992-6091 discloses a method for molding a window frame comprising the steps of applying an adhesive to the surface of a metal core for easy co-extrusion, and covering the outer face of the metal core with a synthetic resin melt-extruded from an extruder; and an apparatus for implementing the method. According to the patent publication, since the adhesive is used in order to improve the bonding strength between the metal core and the synthetic resin, the composite material window frame shows improved adhesion between the different raw materials. Fbwever, the method has disadvantages in terms of non-uniform application of the adhesive, degraded functions of the adhesive components, and frequent occurrence of operational defects. Disclosure of Invention Technical Problem

[12] The present inventors have earnestly and intensively conducted research with the aim of improving the problems associated with the use of an adhesive to enhance the adhesion and to prevent peeling between different materials in the conventional method for applying the adhesive upon co-extrusion of the materials in in-line mode, and as a result, have found that when the shape of the metal core is structurally designed, the peeling between different materials can be prevented without the use of an adhesive.

[13] Based on this finding, it is an object of the present invention to provide a co- extruded composite material structure with superior durability and weather resistance which can prevent the peeling between different materials, ensure uniform quality maintenance during post-processing steps, and express various desired colors. Technical Solution

[14] In order to accomplish the above object of the present invention, there is provided a composite material structure comprising a metal core having a predetermined shape, and a synthetic resin, wherein the composite material structure is produced by co- extruding the metal core and the synthetic resin in in-line mode such that the outer face of the metal core is covered with the synthetic resin melt-extruded from an extruder, and serrations are formed over the outer face of the metal core.

[15] Preferably, a plurality of outwardly-tapered guide grooves are formed on the outer face of the metal core so that separation of the metal core from the synthetic resin can be prevented, and the bonding strength between the different materials can be enhanced.

[16] The composite material structure of the present invention is characterized in that the metal core and the synthetic resin are integrally formed by the serrations and/or the guide grooves, without the use of an adhesive. Since the metal core is engaged with the synthetic resin without the use of an adhesive, the problems of non-uniform application of the adhesive, degraded functions of the adhesive components and frequent occurrence of operational defects can be solved, contributing to the improvement of process efficiency and productivity.

[17] In the present invention, since a metal, preferably aluminum, is used as a material for the inner core, the composite material structure produced by co-extruding the metal core and the synthetic resin in in-line mode satisfies the required structural strength. In addition, post-processing and insertion steps are omitted, ensuring uniform quality maintenance of the composite material structure.

[18] The synthetic resin, preferably poly vinyl chloride (PVC), allows the composite material structure to exhibit superior heat insulation, durability and weather resistance, and to express various desired colors.

[19] Since the composite material structure of the present invention is lightweight and has superior heat insulation to conventional aluminum structures, it can be suitably applied to various structures, such as window frames and factory trusses, particularly, window frames.

[20] In accordance with another aspect of the present invention, there is provided a method for producing a composite material structure comprising the steps of forming serrations over the outer face of a metal core having a predetermined shape, and co- extruding the metal core and a synthetic resin in in-line mode to cover the outer face of the metal core with the synthetic resin melt-extruded from an extruder.

[21] Preferably, the method of the present invention further comprises the step of forming a plurality of outwardly-tapered guide grooves on the outer face of the metal core.

[22] The composite material structure of the present invention can prevent peeling between the metal core, such as aluminum core, and the synthetic resin, such as PVC, without the use of an adhesive, by forming serrations and guide grooves at the interface between the metal core and the synthetic resin to increase the surface area. In addition, the composite material structure of the present invention is integrally formed by covering the outer face of the metal core on which the serrations and guide grooves are formed, with the synthetic resin melt-extruded from an extruder. Furthermore, the composite material structure of the present invention satisfies the required structural strength, greatly improves quality maintenance during post-processing steps, exhibits superior durability and weather resistance, and expresses various desired colors. Advantageous Effects

[23] As explained above, the composite material structure of the present invention can prevent peeling between the metal core, such as aluminum core, and the synthetic resin, such as PVC, without the use of an adhesive, by forming serrations and guide grooves at the interface between the metal core and the synthetic resin to increase the surface area. In addition, the composite material structure of the present invention is integrally formed by covering the outer face of the metal core on which the serrations and guide grooves are formed, with the synthetic resin melt-extruded from an extruder, by action of extrusion pressure. Furthermore, the composite material structure of the present invention greatly improves poor quality maintenance caused during postprocessing steps for imparting sufficient structural strength to conventional PVC-made window frames. Moreover, since the composite material structure of the present invention uses the synthetic resin, such as PVC, it can exhibit superior heat insulation, durability and weather resistance, and can express various desired colors. Description of Drawings

[24] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[25] Fig. 1 is an elevation of a composite material window frame according to one embodiment of the present invention;

[26] Fig. 2 is a view showing the structure of the composite material window frame shown in Fig. 1;

[27] Fig. 3 is a cross-sectional view showing the overall structure of a window assembly including the composite material window frame shown in Fig. 1;

[28] Fig. 4 is a transverse cross-sectional view showing the structure of a window assembly including the composite material window frame shown in Fig. 1;

[29] Fig. 5 is a longitudinal cross-sectional view showing the structure of a window assembly including the composite material window frame shown in Fig. 1;

[30] Fig. 6 is a fragmentary enlarged sectional view of the part A' shown in Fig. 5;

[31] Fig. 7 is a fragmentary sectional view of a conventional composite material window frame produced by using an adhesive; and

[32] Fig. 8 is a schematic view showing the structure of an apparatus for producing a composite material window frame by co-extrusion according to one embodiment of the present invention. Best Mode

[33] The present invention will now be described in more detail with reference to the accompanying drawings.

[34] Fig. 1 is an elevation of a composite material window frame according to one embodiment of the present invention. Figs. 2 to 5 are showing the structure of the composite material window frame shown in Fig. 1, as viewed from various locations. Referring to Figs. 2 to 5, the window frame 1 is composed of an inner metal core 2 and a synthetic resin 3 covering the outer face of the metal core 2.

[35] In one embodiment of the present invention, the metal core 2 has an uneven and grooved outer face. A plurality of guide grooves are formed on the outer face of the metal core 2, and serrations are formed over the outer face of the metal core 2. The plurality of guide grooves are arranged at uniform intervals on upper, lower, left and right sides of the metal core 2.

[36] The uneven and grooved outer face of the metal core 2 of the composite material window frame according to the embodiment of the present invention will be specifically explained below. Fig. 6 is a fragmentary enlarged sectional view of the part A' shown in Fig. 5. As shown in Fig. 6, serrations B in a wave shape are formed over the outer face of the metal core 2, and an outwardly-tapered guide groove C is formed on the outer face of the inner metal core 2 so as to effectively prevent the synthetic resin 3 covering the metal core 2 from being peeled off from the metal core 2. Specifically, when the angle between the outer face of the metal core 2 and the guide groove C is close to 90 , the engagement of the synthetic resin 3 with the metal core is weak, causing separation of the synthetic resin 3 from the metal core 3. As the angle decreases, the engagement of the synthetic resin 3 is strengthened. On the other hand, when the angle is too small, the guide groove C substantially disappears. The angle is preferably in the range of 20 to 70 . The optimum angle at which the synthetic resin 3 is stably engaged with the metal core 2 is 45 .

[37] Fig. 7 is a fragmentary sectional view of a conventional composite material window frame produced by using an adhesive. As shown in Fig. 7, since the outer face of a metal core 2' is planar, the use of an adhesive 4 is required to firmly adhere the metal core 2' to a synthetic resin 3' and to prevent peeling of the metal core 2' from the synthetic resin 3'.

[38] The composite material window frame according to one embodiment of the present invention is produced by co-extrusion in accordance with the following procedure. The serrations are formed over the outer face of the metal core 2, and the guide grooves are formed on the outer face of the metal core 2. The metal core 2 used herein has a high structural strength, superior heat resistance and a low coefficient of linear expansion. Then, the outer face of the metal core 2 is covered with the synthetic resin 3 by a co- extrusion process. The synthetic resin 3 used herein has superior heat insulation, sound-proofness, air- tightness, and corrosion resistance.

[39] It is preferable to simultaneously form the serrations and guide grooves by extrusion molding. For better engagement of the metal core 2 with the synthetic resin 3, it is preferable that the metal core 2 is slightly heated prior to passing through an extruder.

[40] Fig. 8 is a schematic view showing the structure of an apparatus for producing the composite material window frame by co-extrusion according to the embodiment of the present invention. Referring to Fig. 8, a guide 6 for introducing a metal core 2 is arranged at a lower part of an extruder 5. A correction section 7 for correcting the shape and dimensions of the metal core 2, and a co-extrusion section 8, are arranged in a line in a lengthwise direction of the metal core 2.

[41] When the metal core 2 whose outer face is uneven and grooved reaches the front end of the co-extrusion section 8, it is guided by the guide 6, passes through the dimension correction section 7, and arrives at the co-extrusion section 8. In the co- extrusion part 8, the synthetic resin 3 melt-extruded from the extruder 5 covers the outer face of the metal core 2 to produce the composite material window frame according to the embodiment of the present invention.

[42] For purposes of comparison, a linear window frame produced without the use of an adhesive (Comparative Example 1, reference length: 499.43mm), a linear window frame produced by using an adhesive (Comparative Example 2, reference length: 502.45mm), and a window frame structurally designed to have serrations and guide grooves and produced without the use of an adhesive (Example 1, reference length: 498.08mm) were produced. All these composite material window frames were produced by using aluminum as a material for a metal core and PVC as a material for a synthetic resin. The compression/expansion rate of these window frames was measured, and the results are shown in Table 1 below.

[43] The compression/expansion rate is measured while alternating from a very low temperature to a very high temperature. Specifically, the window frames are placed at a high temperature (60 C) for 1 hour, and are then placed at a low temperature (-20 C) for 1 hour. This procedure is continuously repeated for three cycles. The compression/ expansion rate is calculated by dividing an increase or decrease value in the dimensi ons of the window frames measured at high and low temperatures by the respective reference lengths (about 0.5m) and the temperature difference (80 C/2 = 40 C). For reference, the compression/expansion rate of aluminum is 0.2mm/lm/10 C and that of PVC is 0.8mm/lm/10°C. [44] Table 1 [45]

[46] As can be seen from Table 1, the linear window frame produced by co-extrusion without the use of an adhesive (Comparative Example 1) had high compression/ expansion rates at both high and low temperatures, but the window frame structurally designed to have serrations and guide grooves and produced without the use of an adhesive (Example 1) had compression/expansion rates comparable to those of the linear window frame produced by using an adhesive window frame (Comparative Example 2). Accordingly, the window frame wherein aluminum was structurally designed eliminates the use of an adhesive.

[47] As apparent from the foregoing, the window frame according to one embodiment of the present invention solves various problems, e.g., poor heat insulation, sound- proofness, and severe freezing in the winter months, of conventional colored aluminum window frames for expressing various desired colors, as compared to PVC window frames. In addition, although various desired colors can be expressed by using one-touch type finishing materials during post processing, the finishing materials are easily separated and uniform quality maintenance is difficult due to increased processing steps. The window frame according to one embodiment of the present invention can solve these problems. Furthermore, conventional methods wherein a metal such as aluminum is inserted to enhance the structural strength during postprocessing are troublesome and cause increased processing steps. The window frame according to one embodiment of the present invention can solve these problems. Moreover, since the window frame according to one embodiment of the present invention is produced without the use of an additive, the application of adhesive is omitted and the production line is simplified, contributing to the reduction of defects and improvement of productivity.

[48] Although the window frame has been disclosed as an example of the composite material structure according to the present invention, the present invention can be applied to other composite material structures. Accordingly, those skilled in the art will appreciate that various modifications are possible, without departing from the technical spirit of the present invention as disclosed in the accompanying claims. It is to be understood that such modifications are within the scope of the present invention. Industrial Applicability

[49] As explained above, the composite material structure of the present invention can prevent peeling between the metal core, such as aluminum core, and the synthetic resin, such as PVC, without the use of an adhesive, by forming serrations and guide grooves at the interface between the metal core and the synthetic resin to increase the surface area. In addition, the composite material structure of the present invention is integrally formed by covering the outer face of the metal core on which the serrations and guide grooves are formed, with the synthetic resin melt-extruded from an extruder, by action of extrusion pressure. Furthermore, the composite material structure of the present invention greatly improves poor quality maintenance caused during postprocessing steps for imparting sufficient structural strength to conventional PVC-made window frames. Moreover, since the composite material structure of the present invention uses the synthetic resin, such as PVC, it can exhibit superior heat insulation, durability and weather resistance, and can express various desired colors.

Claims

[1] A composite material structure, comprising: a metal core having a predetermined shape; and a synthetic resin, wherein the composite material structure is produced by co-extruding the metal core and the synthetic resin in in-line mode such that the outer face of the metal core is covered with the synthetic resin melt-extruded from an extruder, and serrations are formed over the outer face of the metal core. [2] The composite material structure according to claim 1, further comprising a plurality of outwardly-tapered guide grooves formed on the outer face of the metal core. [3] The composite material structure according to claim 2, wherein the angle between the outer face of the metal core and the guide groove is in the range of 20° to 70°. [4] The composite material structure according to claim 1, wherein the metal core and the synthetic resin are integrally formed without the use of an adhesive. [5] The composite material structure according to claim 1, wherein the metal core is made of aluminum, and the synthetic resin is PVC. [6] The composite material structure according to claim 1, wherein the composite material structure is a window frame. [7] A method for producing a composite material structure, comprising the steps of: forming serrations over an outer face of a metal core having a predetermined shape; and co-extruding the metal core and a synthetic resin in in-line mode to cover the outer face of the metal core with the synthetic resin melt-extruded from an extruder. [8] The method according to claim 7, further comprising the step of forming a plurality of outwardly-tapered guide grooves on the outer face of the metal core.