WO2000039199A1

WO2000039199A1 - Method of manufacturing a plastic composite, and a plastic composite

Info

Publication number: WO2000039199A1
Application number: PCT/FI1999/001072
Authority: WO
Inventors: Marja Marjoniemi; Johanna Pursiainen
Original assignee: Mantereen Kenkätehdas Oy
Priority date: 1998-12-23
Filing date: 1999-12-22
Publication date: 2000-07-06
Also published as: FI106964B; AU3047200A; FI982799A; FI982799A0; WO2000039199A8

Abstract

The invention relates to a method of manufacturing a plastic composite, whereby a composite structure is formed by mixing a matrix plastic (1) with solid particles. The solid particles used in this case are bird feathers (2). A preferred embodiment of the invention is based on the idea that the feathers (2) are arranged into layers one on top of the other, the feathers (2) in each layer being on a same plane and crosswise oriented. The invention also relates to a plastic composite comprising a plastic matrix (1) and solid particles. According to the idea or the invention, the solid particles are bird feathers (2).

Description

METHOD OF MANUFACTURING A PLASTIC COMPOSITE, AND A PLASTIC COMPOSITE

The invention relates to a method of manufacturing a plastic composite, whereby a matrix plastic of a suitable plastic material is mixed with solid particles to provide a desired structure.

The invention further relates to a plastic composite comprising a plastic matrix of a suitable plastic material and solid particles arranged into the plastic matrix.

'Composite' is a general term referring to any combination of two or more materials where the materials act together, but are not dissolved or melted into each other. The constituent that binds the material combination together is called a matrix. Other constituents bound together by the matrix may be solid constituents, such as reinforcing fibres or filling material. In plastic composites, the matrix is a plastic, and the solid reinforcement materials most usually consist of thin fibres, used as such, or of fibres formed into bundles, reinforcement mats, braids, textures or adhesive fabrics. The fibres most typically used are glass and carbon fibres, but in some cases the use of aramide fibres, which are more expensive, may be justified as well.

Heat-insulating plastic structures are made for example by using cellular plastic, the structure of which comprises gas spaces that allow a relatively low thermal conductivity to be obtained. A disadvantage in this kind of a structure is, however, that most cellular plastics in use are compressible. Therefore, when subjected to continuous pressing forces, the plastic gradually compresses and the gas spaces it contains no longer provide insulation, which significantly impairs the heat-insulating capacity of the structure. In addition, the structure does not possess sufficient mechanical properties for all purposes of use.

It is an object of the present invention to provide a novel plastic composite that allows prior art disadvantages to be avoided. A further object is to provide a method of manufacturing the novel plastic composite.

The method of the invention is characterized in that bird feathers are used as solid constituents.

The plastic composite of the invention is further characterized in that bird feathers are arranged as solid constituents. An essential idea of the invention is that the plastic composite comprises a plastic matrix made of a suitable plastic material, and bird feathers arranged into the plastic matrix. An essential idea of a preferred embodiment of the invention is that the feathers are arranged in layers one on top of the other, the feathers in each layer and the separate layers of feathers being substantially parallel with each other. Otherwise the feathers in each layer may be in random orientation. The feathers being positioned crosswise with regard to each other, the feather layers arranged one on top of the other thus form a net-like structure. Further, according to another preferred embodiment of the invention, the matrix plastic and the feathers are attached together by casting or by another method of manufacture, the feather layers thus causing a plural number of gas spaces to be formed into the structure, the gas spaces serving as heat insulation.

An advantage of the invention is that the feathers function as a reinforcement in the plastic composite, a mechanically very strong structure being thereby obtained. With regard to their weight, feathers have extremely good mechanical properties. Measurements have shown that feathers provide a structure with good bending, cutting and tensile properties. The properties of feathers as a reinforcement is particularly emphasized when they are arranged crosswise with regard to each other. Furthermore, crosswise feather layers arranged one on top of the other allow gas spaces to be formed into the composite structure when it is manufactured, thereby allowing a structure with good heat insulation capacity to be obtained. In addition, the heat conductivity of feathers, particularly those of arctic birds, is low. The feathers of arctic geese, for example, themselves contain internal gas spaces that act as heat- insulating portions in the feathers. A further advantage is that feathers, which up to this have only been waste and caused costs and trouble to slaughter houses and other similar establishments, can now be utilized. This is ecologically beneficial because the amount of waste, and, on the other hand, that of industrially manufactured fibres can be reduced. Feathers are also more economical to use than current reinforcement and filling materials. A further advantage of the invention is that, when a porous plastic matrix comprising gas spaces is used, feathers arranged in layers one on top of the other prevent the structure from compressing. Consequently, the structure does not lose its heat insulating capacity and bending properties.

In this context, 'feathers' refer to plumes, down, and the like, covering birds' skin and used as such or in the materials made of these. The invention will be described in greater detail in the accompanying drawings, in which

Figure 1 is a schematic sectional view of a composite structure of the invention; Figure 2 is a microscope picture of a net-like structure formed by feathers arranged into layers one on top of the other;

Figure 3 is a schematic and sectional structural view of an application of the plastic composite of the invention.

Figure 1 illustrates a strongly simplified sectional view of a composite structure of the invention. The composite comprises a plastic matrix 1 , which can be made of basically any plastic material suitable for the purpose. In the manufacturing process, bird feathers 2 are arranged into the plastic matrix, the feathers serving as reinforcement and/or filling material in the structure, as needed. The feathers can be arranged into the structure in a fully random orientation, or, as shown in Figure 1 , they can be arranged into substantially parallel layers one on top of the other. The feather layers can be arranged into the composite structure either so as to be parallel with a surface plane of the structure, parallel with the centre axis of the structure's cross profile, or at a desired angle, depending on the method of manufacture or on the properties the structure is required to have. For the sake of clarity, Figure 1 only shows a simplified schematic view. In practice the amount of feathers is naturally far greater and they preferably overlap with each other at least to some extent.

The plastic composite of the invention can be manufactured by making use of pre-fabricated portions made of feathers, thus allowing the actual composite to be rapidly made. The feathers can be formed into a desired layer in advance for example by pressing them into a suitable composition, by bonding them to form a mat or by casting them into plastic in advance. Figure 2 shows a microscope enlargement of a net-like structure formed by feather layers arranged one on top of the other. The Figure shows a midrib 3a of a topmost feather and a midrib 3b of a feather under the topmost one. The midribs of the feathers have smaller strips and floccules which are further branched into smaller floccules. A structure such as this provides a very efficient reinforcement. The Figure also shows feathers, drawn with a weaker line, that are under the two topmost feathers. When arranged one on top of the other, the crosswise midribs 3a and 3b are capable of receiving compression and tensile forces acting on the structure, which is advantageous when an easily compressible plastic, such as polyurethane (PU), is used.

Figure 3 shows an application of the invention. The composite structure of the invention can be used for example in shoe soles. Shoe soles are required to have good mechanical properties, lightness, and, at least in northern conditions, good thermal insulation capacity. Prior art solutions use a layer made of polyurethane (PU), polyethylene (PE) or polypropylene (PP) provided with a reflective layer attached by gluing, vacuum evaporation or laminating. Such a layer, made for example of a glossy aluminium foil, is meant to reflect thermal radiation emitted from the foot to the shoe back to the foot to provide a warm base layer and, on the other hand, to provide a structure that prevents heat radiation from a hot surface, for example, to the foot. This kind of a solution is disclosed for example in FI patent publication 98042. The plastic used in the solution is polypropylene (PP) which has a heat conductivity of 0.120 Wm^"1K^"1, whereas polyurethane (PU), for example, has a heat conductivity of only about a tenth of that, i.e. 0.015 Wnτ¹K^"1. Furthermore, measurements have been conducted which show that the described reflective layers have hardly any practical significance. Metal films functioning as surfaces reflecting back heat as disclosed in the publication should be mirror surfaces. However, this is only possible in theory, because in an insulating material, laminated metal films follow the roughness of the surfaces they are attached to, and thus the heat radiation acting on the film is no longer reflected as planned, but disadvantageous scattering of the heat radiation occurs. In the present invention, the upper surface of the feather-filled composite structure 4 is provided with a soft textile layer 5, or the like, facing the foot. The lower surface, in turn, is provided with a suitable support layer 6, such as TEXON™. The composite structure of the invention can thus be combined with different kinds of other structural layers, as need arises. The composite structure of Figure 3 uses a porous plastic matrix, for example foamed polyurethane. The plastic matrix comprises gas spaces 7 that provide good thermal insulation. Gas spaces are usually filled with air, but when closed-cell plastics are used, it is possible to use in the matrix a gas which has better insulating properties than air. The Figure also shows gas spaces 8 located at the feathers, the features causing the gas spaces to be formed into the structure during the manufacturing process. Feathers arranged in a crosswise orientation with regard to each other prevent the matrix plastic from being packed tightly against the feathers during the manufacture, spaces not filled with plastic and acting as insulating gas spaces 6 being thus left in the structure. The positioning of the feather layers with regard to each other, the degree of density of the layers, the type of feathers and matrix plastic used, and the method of manufacturing to be applied have an effect on the amount of gas spaces that will be formed into the structure. For example, in casting methods in which overpressure or vacuum is applied, the formation of the gas spaces can be influenced on by regulating the pressure. When necessary, it is possible to form a composite structure which has no gas spaces caused by the mutual positioning of the feathers and the arrangement of the matrix plastic. However, due to the small internal gas spaces in the structure of the feathers themselves, even this structure comprises gas spaces acting as heat-insulating gas pockets. The drawings and the accompanying specification are only meant to illustrate the idea of the invention. The details of the invention may vary within the scope of the claims. Consequently, it is not necessary to arrange the feathers evenly throughout the entire composite structure, but the composite portion comprising feathers can be formed for example only in the middle layer of the structure to be manufactured and/or on its surfaces, other portions being made of the plastic matrix alone, or of plastic reinforced with other solid constituents. Furthermore, the amount and quality of the feathers may vary in different parts of the structure with regard to the desired properties. It is also fully possible to combine the feathers with other reinforcement and filling materials to form composite structures. Yet another possibility is to produce feather-filled matrices by using feathers which are originally very short, or bulk feather made by cutting feathers and used similarly as staple fibre. The invention is not restricted to clothing accessories, but it can be successfully applied to products of the building industry, for example, where structures offering good mechanical and thermal properties at competitive prices are needed.

Claims

1. A method of manufacturing a plastic composite, whereby shoe soles are produced by mixing a matrix plastic (1) made of a suitable plastic material with solid constituents, a shoe sole structure being then formed of the plastic composite for example by casting, characterized in that the solid constituents used are bird feathers (2) which are arranged in layers one on top of the other, the feathers in each layer being substantially parallel with a same plane; that the feathers (2) in the separate layers are crosswise oriented in relation to each other, the feathers in the separate layers thus forming a net- like reinforcement that sustains compression well and the feathers causing heat-insulating gas spaces (8) to be left in the shoe sole structure.

2. A method according to claim ^ characterized in that the plastic material used is cellular plastic.

3. A plastic composite meant to be used for shoe soles and comprising a plastic matrix (1) made of a suitable plastic material and solid constituents arranged into the plastic matrix, characterized in that feathers (2) are arranged as solid constituents, the feathers (2) being arranged into substantially parallel layers one on top of the other in such a way that in each layer, the feathers are substantially parallel with a same plane, and that the orientation of the feathers (2) is such that the feathers positioned crosswise with regard to each other in the separate layers arranged one on top of the other form a net-like reinforcement that sustains compression and that the feathers (2) cause heat-insulating gas spaces (8) to be left in the structure.

4. A plastic composite according to claim 3, characterized in that the plastic matrix (1) is made of cellular plastic, such as polyurethane (PU).