WO2004048072A1 - Rigid composite structure - Google Patents

Rigid composite structure Download PDF

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Publication number
WO2004048072A1
WO2004048072A1 PCT/GB2003/005110 GB0305110W WO2004048072A1 WO 2004048072 A1 WO2004048072 A1 WO 2004048072A1 GB 0305110 W GB0305110 W GB 0305110W WO 2004048072 A1 WO2004048072 A1 WO 2004048072A1
Authority
WO
WIPO (PCT)
Prior art keywords
thermoplastic material
rigid structure
thermoplastic
arrangement
fibres
Prior art date
Application number
PCT/GB2003/005110
Other languages
French (fr)
Inventor
John Crispin Arnold
Patrick William Sinnott
Brett Charles Suddell
Original Assignee
Uws Ventures Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Uws Ventures Ltd filed Critical Uws Ventures Ltd
Priority to GB0510737A priority Critical patent/GB2411145A/en
Priority to AU2003286264A priority patent/AU2003286264A1/en
Publication of WO2004048072A1 publication Critical patent/WO2004048072A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
    • B29C70/465—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs and impregnating by melting a solid material, e.g. sheets, powders of fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B32B15/085—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B21/00—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board
    • B32B21/04—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board comprising wood as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B21/08—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board comprising wood as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/12—Layered products comprising a layer of synthetic resin next to a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/08—Impregnating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B32B5/024—Woven fabric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
    • C08J5/046—Reinforcing macromolecular compounds with loose or coherent fibrous material with synthetic macromolecular fibrous material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
    • B32B2260/02—Composition of the impregnated, bonded or embedded layer
    • B32B2260/021—Fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
    • B32B2260/04—Impregnation, embedding, or binder material
    • B32B2260/046—Synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2311/00—Metals, their alloys or their compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2317/00—Animal or vegetable based
    • B32B2317/16—Wood, e.g. woodboard, fibreboard, woodchips
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2323/00—Polyalkenes
    • B32B2323/04—Polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2323/00—Polyalkenes
    • B32B2323/10—Polypropylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2410/00—Agriculture-related articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2419/00—Buildings or parts thereof
    • B32B2419/06—Roofs, roof membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2479/00—Furniture
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2590/00—Signboards, advertising panels, road signs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2607/00—Walls, panels

Definitions

  • the present invention relates to a composite rigid structure, such as a board, and a method of making it.
  • thermoplastic materials such as polyolefins, e.g. polyethylene, polypropylene, etc.
  • polyolefins e.g. polyethylene, polypropylene, etc.
  • This process requires the use of large scale plant with its consequent high capital costs and yields a product which has a very low value and has to compete with raw materials from large scale industrial plants.
  • a method for making a rigid structure which comprises (i) talcing a layer of fibres of a first thermoplastic material; (ii) placing the fibres of the first thermoplastic material in contact with a second thermoplastic material of lower melting point than the first thermoplastic material to form an arrangement of the first and second thermoplastic materials; (iii) heating and compressing the arrangement formed so that the second thermoplastic material melts and the first thermoplastic material does not melt and (iv) cooling the structure formed. After the heating and compressing of the arrangement, the fibres of the first thermoplastic material are interspersed with second thermoplastic material which, after cooling, forms a rigid structure.
  • the invention also provides a rigid structure which comprises fibres of a first thermoplastic material interspersed with a melted second thermoplastic material of lower melting point than the first thermoplastic material.
  • the first thermoplastic material is a waste thermoplastic material and the invention is particularly useful in using waste and recycled thermoplastic material.
  • the invention is particularly useful for use with polyolefins, for example the first thermoplastic material comprises polypropylene fibres and the second thermoplastic material comprises a polyethylene.
  • polypropylenes of various molecular weights and structures which are produced in fibres.
  • the polypropylene can be copolymerised or blended with other polymers and can have additives incorporated in it.
  • the fibres can be woven and are used to make fabrics which can be used, for example, as sacks, tapes, bags for agricultural products and building materials, etc.
  • any of these polypropylenes and polypropylene copolymers can be used.
  • 'fibres' includes strips, lengths etc. of the material, provided that they can be interspersed with the molten second plastics material and bound together when the molten material cools.
  • the preferred polypropylene structures are those in which the fibres have been woven. Because of the inertness and chemical and physical stability of polypropylene, these products can be difficult to dispose of unless they are recycled in some way.
  • the second thermoplastic material is preferably a polyethylene; polyethylenes are widely used for a vast range of applications, particularly for wrapping, sacks, bags etc. and can be obtained in the form of film, sheet, granules, powder, etc. They can be copolymerised or blended with other polymers and can have additives incorporated in them; any of these products can be used provided that, when they are interspersed with the fibres of the first thermoplastic material, heated and compressed, the polyethylene will melt and the first thermoplastic material does not melt.
  • the relative amounts of the first thermoplastic material and the second thermoplastic material are between 20 and 80 weight per cent of the first thermoplastic material and 80 to 20 per cent of the second thermoplastic material.
  • thermoplastic polymers There can be other components added to either of the thermoplastic polymers or to the mixture or structure if desired.
  • the mixture is preferably heated to a temperature of between 140°C to 170°C and compressed to a pressure of 0.5 to 10 MPa.
  • a plurality of alternating layers of the first and second thermoplastic material can be used to form an arrangement which, after carrying out the method of the invention, gives a structure of the desired thickness; for example, at least ten layers of each material.
  • the total number of layers can be up to one hundred or higher depending on the thickness of the starting layer and the thickness of the final structure which is tombe achieved.
  • the polypropylene fabric When using woven polypropylene fabric waste products as a starting material, the polypropylene fabric can be cut into suitably sized sections, if necessary, and any non required material, such as stitching, handles etc. removed; optionally cleaning and drying may be required.
  • the polyethylene can be used in the form of a sheet, cut into suitably sized sections if necessary or in granules, etc. and also cleaning and drying may be required.
  • the first thermoplastic material is a woven polypropylene fabric and the second thermoplastic material is a polyethylene and the polypropylene fabric and polyethylene are laid up into an uncompacted flat arrangement on a suitable flat surface, most commonly alternating the two materials, although other lay-ups are possible with more of one material than the other, or with the layers arranged in a more random manner.
  • the overall composition is between 20 and 80 per cent (by weight) of polypropylene, with the remainder being polyethylene. Where the product size is to be greater than the cut sections of polypropylene fabric, overlapping of layers can be used to form larger products.
  • the laid-up arrangement is then heated to a temperature between 140 and 170°C and compressed between platens in a suitable press.
  • the pressure to be applied is preferably between 0.5 and 10 MPa.
  • the polyethylene melts, and is forced into the weave of the polypropylene fabric, which remains solid.
  • the product is cooled and the pressure removed, which causes the polyethylene to re-solidify and bind the layers of polypropylene fabric together.
  • the board can then be removed and its edges trimmed if necessary.
  • the cooling can be accomplished by initially passing cooling water tlirough the press with the structure in it to cool the structure, e.g. to about 50°C and then allowing the structure to cool in ambient air.
  • the resultant product can be a board or slightly formed product of any thickness preferably between 1 mm and 20 mm, with good levels of flexural stiffness, flexural and tensile strength, low density, good water and weathering resistance. It can be sawn, drilled, screwed, nailed and welded with safety.
  • a summary of the typical properties of a preferred structure is given below:
  • the product formed has very low environmental impact; not only can it use 100% post-consumer recycled material but also production involves no resins containing phenol, formaldehyde, styrene or other environmentally-damaging products that are found in many other board products.
  • the products themselves are recyclable and quite stable in the outdoor environment.
  • the products can be flat sheets or curved sheets or slightly formed (concave or convex) products which can be used in a variety of applications, ncluding:
  • Construction wall, floor and roof sheeting, shuttering, lining. Agriculture - animal pens, fencing, trays, troughs and shallow channels. Domestic - internal and external furniture, shelving. • Transport - signs, barriers, lorry panels.
  • the products can be produced with a range of surface finishes, simply by incorporating a separate top and/ or bottom sheet into the compression moulding stage. Such surface finishes can include: • Coloured polymer,
  • thermoplastic material has a higher melting point than the second thermoplastic material.
  • Recycled woven polypropylene fibre fabric was obtained in the form of used agricultural fertiliser sacks.
  • the handles and seams of the sacks were cut away and the remaining material was cut into sections of about 0.6m x 0.4m.
  • the fabric weight was 86 g/m 2 .
  • the fabric was washed in an agitating water bath, and then air dried in a tumble dryer at 50°C.
  • Recycled polyethylene film was obtained in the form of used agricultural film, with a film weight of 57g/m 2 . This was cut into sections about 0.6m x 0.4m and washed and dried as with the polypropylene.
  • the two materials were laid up onto a steel platen of size lm x 1.2m.
  • the sections of polypropylene fabric and polyethylene film were overlapped to cover the platen. Alternate layers of polyethylene and polypropylene were laid up, until there were a 1 - 1 -
  • Example 2 a different type of agricultural fertiliser sack was used as the recycled woven polypropylene fabric compared to Example 1. This comprised a 3 -ply weave with a fabric weight of 125 g/m 2 . The polyethylene film used was the same as in Example 1.
  • the processing method was the same as Example 1 except that the compression temperature was 160°C and the compression force was 100 tonnes.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Composite Materials (AREA)
  • Mechanical Engineering (AREA)
  • Textile Engineering (AREA)
  • Laminated Bodies (AREA)
  • Road Paving Structures (AREA)

Abstract

A composite board is formed by heating and compressing layers of a woven waste polypropylene fabric and a polyethylene so that the polyethylene melts and binds the polypropylene fabric together to form a composite board.

Description

Rigid Composite Structure
The present invention relates to a composite rigid structure, such as a board, and a method of making it.
There are large amounts of plastics material which are thrown away and have to be disposed of. This large amount of material is presenting an ever growing problem and a range of recycling schemes and financial incentives and penalties have been proposed and implemented in an effort to reduce this problem. The most useful way of recycling waste products is to turn them into useful products which have an intrinsic value and can be used or sold so that their value can cover all of the costs of recycling. Most recycling schemes for thermoplastic materials such as polyolefins, e.g. polyethylene, polypropylene, etc., involve granulating the material and melting it down for use in e.g. extrusion, moulding processes, etc. This process requires the use of large scale plant with its consequent high capital costs and yields a product which has a very low value and has to compete with raw materials from large scale industrial plants.
We have now devised an improved method for recycling certain thermoplastic materials which yields a useful structure.
According to the invention there is provided a method for making a rigid structure which comprises (i) talcing a layer of fibres of a first thermoplastic material; (ii) placing the fibres of the first thermoplastic material in contact with a second thermoplastic material of lower melting point than the first thermoplastic material to form an arrangement of the first and second thermoplastic materials; (iii) heating and compressing the arrangement formed so that the second thermoplastic material melts and the first thermoplastic material does not melt and (iv) cooling the structure formed. After the heating and compressing of the arrangement, the fibres of the first thermoplastic material are interspersed with second thermoplastic material which, after cooling, forms a rigid structure.
The invention also provides a rigid structure which comprises fibres of a first thermoplastic material interspersed with a melted second thermoplastic material of lower melting point than the first thermoplastic material.
Preferably the first thermoplastic material is a waste thermoplastic material and the invention is particularly useful in using waste and recycled thermoplastic material.
The invention is particularly useful for use with polyolefins, for example the first thermoplastic material comprises polypropylene fibres and the second thermoplastic material comprises a polyethylene.
There is a range of polypropylenes of various molecular weights and structures which are produced in fibres. The polypropylene can be copolymerised or blended with other polymers and can have additives incorporated in it. The fibres can be woven and are used to make fabrics which can be used, for example, as sacks, tapes, bags for agricultural products and building materials, etc.
In the present invention any of these polypropylenes and polypropylene copolymers can be used.
The term 'fibres' includes strips, lengths etc. of the material, provided that they can be interspersed with the molten second plastics material and bound together when the molten material cools.
The preferred polypropylene structures are those in which the fibres have been woven. Because of the inertness and chemical and physical stability of polypropylene, these products can be difficult to dispose of unless they are recycled in some way.
The second thermoplastic material is preferably a polyethylene; polyethylenes are widely used for a vast range of applications, particularly for wrapping, sacks, bags etc. and can be obtained in the form of film, sheet, granules, powder, etc. They can be copolymerised or blended with other polymers and can have additives incorporated in them; any of these products can be used provided that, when they are interspersed with the fibres of the first thermoplastic material, heated and compressed, the polyethylene will melt and the first thermoplastic material does not melt.
Preferably the relative amounts of the first thermoplastic material and the second thermoplastic material are between 20 and 80 weight per cent of the first thermoplastic material and 80 to 20 per cent of the second thermoplastic material.
There can be other components added to either of the thermoplastic polymers or to the mixture or structure if desired.
When the first thermoplastic material is a polypropylene and the second thermoplastic material is a polyethylene, the mixture is preferably heated to a temperature of between 140°C to 170°C and compressed to a pressure of 0.5 to 10 MPa.
In forming the arrangement, a plurality of alternating layers of the first and second thermoplastic material can be used to form an arrangement which, after carrying out the method of the invention, gives a structure of the desired thickness; for example, at least ten layers of each material. There can be a different number of layers of the first and second thermoplastic material, e.g. two layers of the second thermoplastic material for each layer of the first thermoplastic material and other ratios can be used or a random arrangement of layers used. The total number of layers can be up to one hundred or higher depending on the thickness of the starting layer and the thickness of the final structure which is tombe achieved.
When using woven polypropylene fabric waste products as a starting material, the polypropylene fabric can be cut into suitably sized sections, if necessary, and any non required material, such as stitching, handles etc. removed; optionally cleaning and drying may be required.
The polyethylene can be used in the form of a sheet, cut into suitably sized sections if necessary or in granules, etc. and also cleaning and drying may be required.
In a preferred embodiment of the invention the first thermoplastic material is a woven polypropylene fabric and the second thermoplastic material is a polyethylene and the polypropylene fabric and polyethylene are laid up into an uncompacted flat arrangement on a suitable flat surface, most commonly alternating the two materials, although other lay-ups are possible with more of one material than the other, or with the layers arranged in a more random manner. The overall composition is between 20 and 80 per cent (by weight) of polypropylene, with the remainder being polyethylene. Where the product size is to be greater than the cut sections of polypropylene fabric, overlapping of layers can be used to form larger products.
The laid-up arrangement is then heated to a temperature between 140 and 170°C and compressed between platens in a suitable press. The pressure to be applied is preferably between 0.5 and 10 MPa. When heated and compressed, the polyethylene melts, and is forced into the weave of the polypropylene fabric, which remains solid. After a suitable compression time, the product is cooled and the pressure removed, which causes the polyethylene to re-solidify and bind the layers of polypropylene fabric together. The board can then be removed and its edges trimmed if necessary. In this embodiment, the cooling can be accomplished by initially passing cooling water tlirough the press with the structure in it to cool the structure, e.g. to about 50°C and then allowing the structure to cool in ambient air.
The resultant product can be a board or slightly formed product of any thickness preferably between 1 mm and 20 mm, with good levels of flexural stiffness, flexural and tensile strength, low density, good water and weathering resistance. It can be sawn, drilled, screwed, nailed and welded with safety. A summary of the typical properties of a preferred structure is given below:
Flexural strength 30-40 MPa
Flexural stiffness l - 1.3 GPa
Tensile strength -100 MPa
Tensile stiffness ~6 GPa
Strain to failure >20 %
Density l.O g/cm3
It is a feature of the invention that the product formed has very low environmental impact; not only can it use 100% post-consumer recycled material but also production involves no resins containing phenol, formaldehyde, styrene or other environmentally-damaging products that are found in many other board products. The products themselves are recyclable and quite stable in the outdoor environment.
In their final form, the products can be flat sheets or curved sheets or slightly formed (concave or convex) products which can be used in a variety of applications, ncluding:
Construction — wall, floor and roof sheeting, shuttering, lining. Agriculture - animal pens, fencing, trays, troughs and shallow channels. Domestic - internal and external furniture, shelving. • Transport - signs, barriers, lorry panels. The products can be produced with a range of surface finishes, simply by incorporating a separate top and/ or bottom sheet into the compression moulding stage. Such surface finishes can include: • Coloured polymer,
• Embossed or textured surface,
• Metallic foil surface,
• Wood veneer and wood effect surface etc.
Although the invention has been described with reference to polypropylenes and polyethylenes, other materials can be used provided the first thermoplastic material has a higher melting point than the second thermoplastic material.
The invention is illustrated in the Examples.
Example 1
Recycled woven polypropylene fibre fabric was obtained in the form of used agricultural fertiliser sacks. The handles and seams of the sacks were cut away and the remaining material was cut into sections of about 0.6m x 0.4m. The fabric weight was 86 g/m2. The fabric was washed in an agitating water bath, and then air dried in a tumble dryer at 50°C.
Recycled polyethylene film was obtained in the form of used agricultural film, with a film weight of 57g/m2. This was cut into sections about 0.6m x 0.4m and washed and dried as with the polypropylene.
The two materials were laid up onto a steel platen of size lm x 1.2m. The sections of polypropylene fabric and polyethylene film were overlapped to cover the platen. Alternate layers of polyethylene and polypropylene were laid up, until there were a 1 - 1 -
total of 30 polypropylene layers and 31 polyethylene layers, including the top and bottom layer. This gave a composition of 60% polypropylene, 40% polyethylene. A second steel platen was then placed on top of the layers and this arrangement was heated in a compression moulding press to a temperature of 150°C. A slight force of 2 tonnes was applied to the material to hold the layers together while they heated up. After 5 minutes at 150°C the compression force was increased to 200 tonnes. This pressure was held on for 2 minutes, after which cooling water was passed through the compression moulder to reduce the temperature. Once the temperature had dropped to below 50°C, the pressure was removed and the compacted sheet was removed.
Following edge trimming, the properties of this material were:
Sheet thickness 4.3 mm
Flexural strength 32 MPa
Flexural stiffness 1.2 GPa
Tensile strength 95 MPa
Tensile stiffness 5.3 GPa
Strain to failure ~ 24 %
Density 1.0 g /cm3
Example 2
In this example, a different type of agricultural fertiliser sack was used as the recycled woven polypropylene fabric compared to Example 1. This comprised a 3 -ply weave with a fabric weight of 125 g/m2. The polyethylene film used was the same as in Example 1.
In this case, neither material was washed or dried before compaction, and a layer arrangement of 2 layers of polyethylene film for every layer of polypropylene fabric was used. This gave a composition of 52% polypropylene and 48%) polyethylene. A lay up with a total of 25 polypropylene fabric layers and 52 polyethylene film layers was used.
The processing method was the same as Example 1 except that the compression temperature was 160°C and the compression force was 100 tonnes.
Following edge trimming, the properties of this material were:
Sheet thickness 6.2 mm
Flexural strength 36 MPa
Flexural stiffness 1.4 GPa
Tensile strength 93 MPa
Tensile stiffness 5.6 GPa
Strain to failure -21%
Density l.l g/cm3

Claims

Claims
1. A method for making a rigid structure which comprises (i) taking a layer of fibres of a first thermoplastic material; (ii) placing the fibres of the first thermoplastic material in contact with a second thermoplastic material of lower melting point than the first thermoplastic material to form an arrangement of the first and second thermoplastic materials; (iii) heating and compressing the arrangement formed so that the second thermoplastic material melts and the first thermoplastic material does not melt and (iv) cooling the structure formed.
2. A method as claimed in claim 1 in which the first and second thermoplastic materials comprise a polyolefin or a polyolefin copolymer.
3. A method as claimed in claim 2 in which the first thermoplastic material comprises a polypropylene and the second thermoplastic material comprises a polyethylene.
4. A method as claimed in claim 2 or 3 in which the first thermoplastic material comprises a woven polypropylene.
5. A method as claimed in any one of the preceding claims in which the relative amounts of the first thermoplastic material and the second thermoplastic material is between 20 and 80 weight per cent of the first thermoplastic material and 80 to 20 per cent of the second thermoplastic material.
6. A method as claimed in any one of the preceding claims in which the arrangement of first thermoplastic material and the second thermoplastic material is heated to a temperature of between 140°C to 170°C and compressed to a pressure of 0.5 to 10 MPa.
7. A method as claimed in any one of the preceding claims in which there are a plurality of layers of the first and second thermoplastic material.
8. A method as claimed in any one of the preceding claims in which the first thermoplastic material comprises woven fibres and at least one layer of the first and second thermoplastic materials are laid up into an uncompacted flat arrangement and the laid-up arrangement is then heated and compressed.
9. A method as claimed in claim 8 in which the first thermoplastic material comprises woven fibres and at least one layer of the first and second thermoplastic materials are laid up into an uncompacted flat arrangement on a flat surface; the laid-up arrangement is then heated and compressed between platens and the second thermoplastic material melts and is forced into the weave of the first thermoplastic material, which remains solid; the pressure is then removed, which causes the second thermoplastic material to re-solidify and bind the fibres of the first thermoplastic material together.
10. A method as claimed in any one of the preceding claims in which a separate top and/ or bottom sheet is added to the arrangement before it is heated and compressed.
11. A method as claimed in claim 10 in which the top and/or bottom sheet is selected from coloured polymers, embossed or textured surfaces, metallic foil surfaces, wood veneer and wood effect surfaces.
12. A rigid structure which comprises fibres of a first thermoplastic material interspersed with a melted second thermoplastic material of lower melting point than the first thermoplastic material.
13. A rigid structure as claimed in claim 12 in which the first and second thermoplastic materials comprise a polyolefin or a polyolefin copolymer.
14. A rigid structure as claimed in claim 13 in which the first thermoplastic material comprises a polypropylene and the second thermoplastic material comprises a polyethylene.
15. A rigid structure as claimed in claim 13 or 14 in which the first thermoplastic material comprises a woven polypropylene.
16. A rigid structure as claimed in any one of claims 12 to 15 in which the relative amounts of the first themioplastic material and the second thermoplastic material is between 20 and 80 weight per cent of the first thermoplastic material and 80 to 20 per cent of the second thermoplastic material.
17. A rigid structure as claimed in any one of claims 12 to 16 in which there are a plurality of layers of the first and second thermoplastic material.
18. A rigid structure as claimed in any one of claims 12 to 17 in which there is a separate top and/ or bottom sheet incorporated in the structure.
19. A rigid structure as claimed in claim 21 in which the top and/or bottom sheet is selected from coloured polymers, embossed or textured surfaces, metallic foil surfaces, wood veneer and wood effect surfaces.
20. A rigid structure as claimed in any one of claims 12 to 19 which is from 1 to 20mm thick.
21. A rigid structure as claimed in any one of claims 12 to 19 which is board.
22. A rigid structure as claimed in any one of claims 12 to 19 which is curved.
23. A rigid structure made by the method of any one of claims 1 to 11.
24. A rigid structure as claimed in claim 23 which has a thickness of from 1 to 20mm.
PCT/GB2003/005110 2002-11-22 2003-11-24 Rigid composite structure WO2004048072A1 (en)

Priority Applications (2)

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GB0510737A GB2411145A (en) 2002-11-22 2003-11-24 Rigid composite structure
AU2003286264A AU2003286264A1 (en) 2002-11-22 2003-11-24 Rigid composite structure

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB0227237.5A GB0227237D0 (en) 2002-11-22 2002-11-22 Composite Board
GB0227237.5 2002-11-22

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Publication number Priority date Publication date Assignee Title
FR2923179A1 (en) * 2007-11-02 2009-05-08 Carbone Forge Sarl PROCESS FOR THE MANUFACTURE BY MOLDING A THERMOPLASTIC COMPOSITE PIECE
US7641962B2 (en) 2004-11-12 2010-01-05 Woven Image Pty Ltd. Fibre privacy or room-divider panel
EP3444105A1 (en) * 2017-08-14 2019-02-20 The Boeing Company Hybrid non-woven composite part
US10343328B1 (en) 2014-01-31 2019-07-09 Ecostrate Sfs, Inc. Structural composites method and system
US10358554B2 (en) * 2012-07-15 2019-07-23 Ecostrate Sfs, Inc. Thermoformed structural composites
US11820881B2 (en) 2020-04-02 2023-11-21 Singular Solutions Inc. Plastic pro-biodegradation additives, biodegradable plastic compositions, and related methods

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Publication number Priority date Publication date Assignee Title
DE10048209A1 (en) * 1999-09-30 2001-04-05 Sumitomo Chemical Co Polypropylene based fiber reinforced composite containing reinforcing fibers and a matrix resin obtained from different polypropylene based resins, exhibits excellent adhesion between the fibers and matrix resin and strength
WO2001032405A1 (en) * 1998-04-03 2001-05-10 Griffith Research And Development Enterprises Pty. Limited Fibre reinforced thermoplastic composite

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WO2001032405A1 (en) * 1998-04-03 2001-05-10 Griffith Research And Development Enterprises Pty. Limited Fibre reinforced thermoplastic composite
DE10048209A1 (en) * 1999-09-30 2001-04-05 Sumitomo Chemical Co Polypropylene based fiber reinforced composite containing reinforcing fibers and a matrix resin obtained from different polypropylene based resins, exhibits excellent adhesion between the fibers and matrix resin and strength

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7641962B2 (en) 2004-11-12 2010-01-05 Woven Image Pty Ltd. Fibre privacy or room-divider panel
FR2923179A1 (en) * 2007-11-02 2009-05-08 Carbone Forge Sarl PROCESS FOR THE MANUFACTURE BY MOLDING A THERMOPLASTIC COMPOSITE PIECE
US10358554B2 (en) * 2012-07-15 2019-07-23 Ecostrate Sfs, Inc. Thermoformed structural composites
US10343328B1 (en) 2014-01-31 2019-07-09 Ecostrate Sfs, Inc. Structural composites method and system
EP3444105A1 (en) * 2017-08-14 2019-02-20 The Boeing Company Hybrid non-woven composite part
US10773468B2 (en) 2017-08-14 2020-09-15 The Boeing Company Hybrid non-woven composite part
US11820881B2 (en) 2020-04-02 2023-11-21 Singular Solutions Inc. Plastic pro-biodegradation additives, biodegradable plastic compositions, and related methods

Also Published As

Publication number Publication date
GB0227237D0 (en) 2002-12-31
GB0510737D0 (en) 2005-06-29
GB2411145A (en) 2005-08-24
AU2003286264A1 (en) 2004-06-18

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