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
  • B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
  • B29C70/543—Fixing the position or configuration of fibrous reinforcements before or during moulding
• • 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
  • B29C70/06—Fibrous reinforcements only
  • B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
  • B29C70/16—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length
  • B29C70/22—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length oriented in at least two directions forming a two dimensional structure
• • 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
  • B29C70/06—Fibrous reinforcements only
  • B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
  • B29C70/16—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length
  • B29C70/24—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length oriented in at least three directions forming a three dimensional structure
• • 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
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2101/00—Use of unspecified macromolecular compounds as moulding material
  • B29K2101/12—Thermoplastic materials

Definitions

• the invention relates to a product manufactured from a reinforcement and a matrix plastic, presented in the introductory part of the appended claim 1.
• the invention relates also to a method for manufacturing a re ⁇ inforced product, presented in the introductory part of the appended claim 6.
• a reinforced product by placing reinforce ⁇ ments in a mould cavity, whereafter matrix plastic is introduced into the mould cavity for moulding.
• the reinforcements are thus embedded in matrix plastic, forming a composite piece.
• the reinforcements are usually structures, such as woven or knitted fabrics, made of glass fibre or corresponding strong fibres.
• the matrix can be either a thermo ⁇ plastic (normal injection moulding), a thermoplastic formed of fluid components supplied in connection with moulding (reaction injection moulding, RIM), or a thermosetting plastic (resin transfer moulding, RTM).
• the product according to the invention is primarily characterized in what is presented in the characterizing part of the ap ⁇ pended claim 1.
• the reinforcement of the product consists of a sort of a reinforcement preform where the reinforcing fibres are arranged at de ⁇ sired, fixed directions thanks to the fact that they are attached to each other by means of a thermoplastic matrix before the actual casting.
• Figure 1 shows a reinforcement for use in the product according to the invention as seen from the front
• Figure 2 shows a second reinforcement for use in the invention in a perspective view
• Figure 3 shows a cross-sectional view of the mould before moulding
• Figure 4 shows examples of mouldings according to the invention
• Figure 5 illustrates the treatment of the reinforcement preform
• Figure 6 illustrates a method for the manufacture of the product.
• Figure 1 shows a reinforcement for use in the product. It is a reinforce ⁇ ment preform formed of a continuous-fibre reinforced thermoplastic im ⁇ pregnate achieved by impregnating a bundle of several continuous parallel reinforcing filaments with a thermoplastic matrix, whereby a yam 1 is formed, reinforced by filaments cohered by the thermoplastic.
• the filaments are indicated by the reference numeral 2, and al ⁇ though only few filaments are shown for the sake of clarity, there can be even more than a hundred, normally 1000 — 2000 parallel filaments in one yam.
• the cross-sectional form of the yam itself can have a circular or flat or another shape, depending on the impregnating technique. It is common to all yams that the solidified thermoplastic matrix joins the continuous filaments together. This kind of yam will be also called “prepreg" hereinafter.
• Figure 1 shows a two-dimensional reinforcement preform structure.
• the main directions of the yam 1 and thus the reinforcing filaments 2 extend always in the same plane or in parallel planes in the reinforcement preform, where different sections of the yam 1 are joined together by molten thermoplastic matrix.
• the sections of the yam 1 can be brought together e.g. by braiding or weaving solidified thermoplastic impregnate, whereby different sections of the yarn 1 are melted to ⁇ gether into a planar structure by means of a separate thermal treat ⁇ ment.
• Several planar layers of this kind can be applied on top of each other to form a rigid two-dimensional reinforcement preform.
• the same continuous yam 1 can be used for forming a pre ⁇ form, it can also be made of several different yams 1 , having e.g. dif ⁇ ferent reinforcing structures.
• yams 1 having e.g. dif ⁇ ferent reinforcing structures.
• parallel sections of the yam 1 can have a stronger reinforcing effect than sections of the yarn 1 extending in the transverse direction thereto.
• yarns comprising the same filament material but having different filament/thermoplastic matrix ratios, or yarns comprising dif ⁇ ferent filaments can be used.
• sections of the yarn 1 run- ning in one direction can comprise a glass fibre reinforcement
• sections of the yam 1 running in the other direction can comprise a car ⁇ bon fibre reinforcement.
• Figure 2 shows part of another kind of reinforcement preform.
• This can be called a three-dimensional structure, because it has, in addition to the yarn sections in the same plane described above, also sections of the yam 1 having a main direction transverse to the said planes.
• This will increase the possibilities in reinforcing the product in desired direc- tions, and also here combinations of different kinds of yams 1 can be used on the same principle as described above.
• the sections of the yam 1 running in the direction of the third dimension are placed through openings 3 left between the sections of the yam 1 forming the two-dimensional structure, and they can thus run through several parallel two-dimensional planes.
• the cross-sections of the yams running through the openings 3 do not need to fill in the openings, whereby the moulding material can penetrate into the reinforcement preform also through the openings 3.
• Another three-dimensional structure comprises planes extending in dif ⁇ ferent directions, either different two-dimensional planes connected to each other or different sections of the same two-dimensional plane.
• the structure can be achieved e.g. by winding an impregnated yam at a desired angle around a suitable piece, such as a cylinder (filament winding).
• the yams can be mutually connected at inter ⁇ sections either by heating the finished preform or by heating the yam, wherein the thermoplastic which is still in a soft state joins different sec ⁇ tions of the yarn 1 together in connection with winding.
• Figure 3 shows a reinforcement preform 5, consisting of yams 1 de ⁇ scribed above and placed in a mould cavity 4.
• the figure illustrates also the way how the reinforcement preform 5 can be used for supporting a core 6 in the mould cavity 4, thanks to the rigid reinforcement preform 5 having contact points both to the wall of the mould cavity 4 and to the surface of the core 6.
• the rigid reinforcement preform in a way fixes the core in its position so that it cannot be displaced by high moulding pressures.
• the reinforcement preform 5 can be helpful e.g. in the manufacture of long tubular pieces or other elongate pieces, inside which the reinforcement preform is left.
• the reinforce ⁇ ment preform is suitable for supporting solid cores to be drawn out after the moulding, as well as for supporting soluble cores.
• the reinforcement preform is thus made of two or more reinforce ⁇ ment preforms manufactured by a simpler method, by joining the pre- forms to each other mechanically or by preheating them, wherein they adhere to each other thanks to the thermoplastic.
• Preforms of this kind can be shaped at their edges e.g. to have overlapping structures, such as planes or yam sections, which connect the preforms mechanically to each other. Besides a mechanical connection, also preheating can thus be used. Partial preforms of this kind can be joined either before inserting the whole reinforcement preform into the mould or, when re ⁇ quired by the shape of the mould cavity, they can be joined first in the mould.
• Moulding is conducted using some generally known moulding method.
• the moulding is conducted with the same thermoplastic as the matrix of the thermoplastic impregnate of the reinforcement preform. This secures a particularly good adhesion of the matrix to be fed during the moulding and the matrix polymer of the reinforcement preform without interfaces, as well as good adhesion of reinforcing filaments to the matrix of the composite piece.
• the reinforcement preform can further be preheated before moulding with the matrix material.
• the matrix material e.g. for injection moulding with a thermoplastic (injection moulding or RIM)
• RIM injection moulding
• Figure 4 shows still some feasible pieces to be moulded by the method, in cross-sectional form.
• the reinforcement preform can be placed at any point of the piece according to the need, e.g. on the outer surface, in the middle or on the inner surface of the tu ⁇ bular pieces shown in the figure.
• the construction of the piece can comprise combinations of the previous figures in such a way that there are several reinforcement layers.
• the rein ⁇ forcement preform according to the invention can be inserted in the mould cavity forming the finished piece, to achieve a desired content of the material of the reinforcement preform and the desired orientation of the reinforcement in the mould cavity.
• Tests have shown that a reinforcement preform manufactured of a thermoplastic prepreg comprising continuous fibre reinforcement can be treated further after the manufacture of the preform using heat and pressure. Consequently, the reinforcement preform can be manufac- tured in a manner as simple as possible, to be as close to the dimen ⁇ sions and shape of the finished product as possible.
• the preparation of the prepreg form to its final shape is carried out by heating the prepreg form to a suitable temperature.
• the temperature is in the same range as the temperature of thermoplastics in sheet forming.
• the preform is turned into its final form in the mould by using pressure.
• pieces with a circular cross-section, manufactured by winding, can be turned into other shapes by heat forming.
• the different stages of this method are shown in Figure 5.
• the fibre content of the yam 1 used can vary within a very wide range, but typically the fibre content is 20...60 % of the total volume.
• the content of the material of the reinforcement preform in the finished mould preform can vary within a very wide range, but it is typically in the range 40...60 % of the volume of the final product.
• the method according to the invention is suitable particularly for injec ⁇ tion moulding of thermoplastics and reaction injection moulding with polyamide, and it can be used for manufacturing similar pieces as with normal injection moulding and RIM techniques.
• the method can further be automated e.g. in injection moulding so that a robot or a manipulator fits the reinforcement preform into the mould cavity when the mould is open.
• a yam or "prepreg” with a continuous fibre reinforcement and with a desired cross-sectional shape is manufactured from any thermoplastic and reinforcement.
• the choice of materials is by far larger than with the techniques of RTM and RIM.
• the reinforcement preform is made e.g. by winding so that the sections of the yam adhere to each other at inter- sections.
• the preforms made in this way can be further processed into a desired shape, stored and transported completely freely. Their strength is superior compared with fibre pre- forms made using RTM or RIM.
• the reinforcement preform is possibly preheated. This is to eliminate mould shrinkage of the preform and the melted mass in the process. In practice, the preform can be heated very close to the softening temperature of the moulding plastic.
• the reinforcement preform is placed in the mould cavity.
• a coextruded prepreg means a prepreg comprising two partial matrices on top of each other.
• the inner part of the prepreg is a normal prepreg reinforced with continuous fibres.
• the surface part of the prepreg is pure plastic with no reinforcement.
• the surface part must be of a plastic with very good adhesion to the inner layer.
• the surface layer can be of the same basic plastic as the inner part, it can be a similar type of plas ⁇ tic as the inner part, or it can be of a completely different polymer than the inner part.
• the purpose of the surface layer can be varied, depend- ing on the properties required of its structure; for example, its adher ⁇ ence or dyeability can be better, or it can be used to eliminate entry of the fibre-reinforced prepreg to the surface layer.
• a plastic that melts (softens) at a lower temperature can be used, thus facilitating the "welding" of prepregs together.
• the reinforced product can be manufactured of a reinforcement preform and a thermoplastic matrix also immediately after the forming of the reinforcement preform.
• a three-dimensional reinforcement preform according to the final profile (in the case of this figure, a tube) is manu ⁇ factured by braiding (by winding or some other method) starting from a prepreg with continuous fibre reinforcement.
• the preform is wound on a mandrel 7.
• the prepregs are joined to each other by weld- ing with heat at their intersections.
• the reinforcement preform thus formed is led to a tool 8 in the extruder (in this case a crosshead die), where a continuous thermoplastic matrix is extruded around the rein ⁇ forcement preform, simultaneously penetrating into the net structure of the reinforcement preform and forming a fully tight construction.
• the reinforcement profile is led to a calibrating tool 9 where the final dimensions of the product are calibrated to be at a desired level. It is also possible to use the extrusion technique in another way to apply matrix plastic in connection with the reinforcement preform 5, for ex ⁇ ample for forming planar pieces or pieces with a curved cross-section, of reinforcement preforms with corresponding shapes. Preforms formed by winding or in another manner can also be temporarily stored before extrusion.
• the tensile strength values of the materials are as follows:
• a fibre content in the range of 20...30 Vol.-% is reached in the final product, such a product can easily have a tensile strength in the range of 200...300 MPa. If the reinforcements can be installed in the piece in a fully controlled manner, it is possible to raise the tensile strength in the direction of the fibres in the piece locally to the range of 400...700 MPa without major problems.
• liquid crystal polymers which have very low melt viscosity and which can be used for manufac ⁇ turing very large pieces with thin walls.
• injection moulding by this technique can be used for manufacturing pieces with such strength properties that are not possi- ble with any other known technique.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Mechanical Engineering (AREA)
• Reinforced Plastic Materials (AREA)
• Laminated Bodies (AREA)
• Moulding By Coating Moulds (AREA)

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Publications (1)

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Citations (4)

• 1994
  • 1994-02-04 FI FI940535A patent/FI97037C/fi active
• 1995
  • 1995-07-17 WO PCT/FI1995/000401 patent/WO1997003813A1/en active Application Filing

Patent Citations (4)

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