Fibre reinforced composite moulding

Abstract

A method of producing molded articles. The method uses a fibrous material and a first and second resin material. The first resin material is at least partially cured before being combined with the fibrous material and the second resin material. The molding material is inserted into a mold and processed to form a molded article by providing energy. The molded article is produced using less energy than would be necessary for processing a molding material which did not include a partially cured first resin material.

Claims

1. A method of manufacturing a molded article comprising: a) providing a molding material comprising a fibrous reinforcement material, a first resin material and a second resin material, the first resin material being at least partially processed; followed by b) providing the molding material into a mold to form a molding; and c) processing the molding in said mold to form the molded article by providing energy input to the molding, the energy input for processing the molding to form the molded article being less than the energy input required for manufacturing the molded article from a molding comprising the same volume of said first and second resin material in which the first resin material is not at least partially processed.

2. A method of manufacturing a molded article according to claim 1 wherein said in-mold processing comprises heating said molding to a cure temperature and maintaining the molding at a dwell temperature in a dwell stage, the dwell stage being shorter than the dwell stage required for manufacturing the molded article from a molding comprising the same first and second resin material in which the first resin material is unprocessed.

3. The method of claim 1, wherein the molding is processed by heating to a cure temperature and maintaining the molding at a dwell temperature in a dwell stage, the dwell stage being shorter than the dwell stage required for manufacturing the molded article from a molding comprising the same first and second resin material in which the first resin material is unprocessed.

4. The method of claim 2, wherein in-mold processing comprises a dwell temperature which is higher than the dwell temperature required for manufacturing the molded article from a molding comprising the same first and second resin material in which the first resin material is unprocessed.

5. The method of claim 1, wherein the partially processed first resin material is fully cured.

6. A method of manufacturing a molding material comprising: a) providing a fibrous reinforcement material, a first resin material and a second resin material, the first and second resin materials being contact with said fibrous reinforcement material, the second fibrous reinforcement material and said first and second resin materials together forming a molding; and b) at least partially processing the first resin material before locating the molding material in relation to a mold, wherein the step of partially processing comprises at least part curing of the first resin material.

7. A molding material comprising a fibrous reinforcement material, a first resin material and a second resin material, the respective resin materials being in contact with said fibrous reinforcement material, the first resin material being at least partially processed prior to in-mold processing of the molding material.

8. The material of claim 7, wherein the energy input for processing the molding to form the molded article is less than the energy input required for in-mold processing of the molded article from a molding material comprising the same first and second resin material in which the first resin material is unprocessed.

9. The material of claim 7, wherein the dwell stage during processing is shorter than the dwell stage required for manufacturing the molded article from a molding comprising the same first and second resin material in which the first resin material is unprocessed.

10. The material of claim 7, wherein the material has a dwell temperature which is higher than the dwell temperature required for manufacturing the molded article from a molding comprising the same first and second resin material in which the first resin material is unprocessed.

11. The material of claim 7, wherein the fibrous reinforcement material comprises a first layer comprising the first resin material and a second layer comprising the second resin material, the partially processed first layer being in contact with the second layer to form the molding material.

12. The material of claim 7, wherein one or more reinforcement layers are at least partially impregnated with a. resin material.

13. The material of claim 7, wherein the resin material is conjoined to the surface of a fibrous reinforcement layer, whilst the fibrous reinforcement material provides an air path through its structure.

Description

(1) The invention will now be clarified by way of example only and with reference to the accompanying drawings in which

(2) FIG. 1 present a diagrammatic view of a moulding according to an embodiment of the invention;

(3) FIG. 2 presents a diagrammatic view of a moulding according to another embodiment of the invention;

(4) FIG. 3 presents a diagrammatic view of a process for producing the moulding material according to a further embodiment of the invention;

(5) FIG. 4 presents a diagrammatic view of another process for producing the moulding material according to a further embodiment of the invention, and

(6) FIG. 5 presents a comparison between a conventional moulding cure and a moulding cure according to the invention.

(7) FIG. 1 shows a moulding material 10 comprising a first fibrous layer 14 impregnated with a first resin which has been cured by processing and a further fibrous layer 12 impregnated with a second resin which has not been processed.

(8) FIG. 2 shows an alternative moulding material 20 comprising a fibrous layer which is impregnated with a first resin material 24 and a second resin material 22. The first resin material is partially cured by processing, whereas the second resin material 22 is uncured.

(9) The moulding materials 10,20 can be assembly on a roll by winding and may be laid up in a mould as a single layer or in multiple layers or in combination with other moulding materials to form a moulding. Once laid up, the moulding is processed by curing the moulding to produce a moulded article.

(10) FIG. 3 shows the schematic process for manufacturing the moulding material of the invention. The process comprises multiple steps. First a preimpregnated fibrous material is provided as a prepreg precursor 40. A section of this material is cured 42 to form a cured prepreg, preferably whilst the reinforcement material is under tension. Another section of the material remains unprocessed. The cured prepreg and the unprocessed prepreg are then combined in step 44 to form a moulding material 46.

(11) In use, one or more layers of the moulding materials 10,20 are applied to a mould surface to form a moulding. The moulding materials may also be combined with other additional moulding materials.

(12) The moulding is subsequently processed using a suitable cure schedule which includes a temperature increase to a cure temperature, and a single dwell stage for a period of time at or above the cure temperature during which the moulding reacts to full cure. The dwell stage is followed by cooling of the moulding and its release from the mould as a moulded article.

(13) FIG. 4 shows a particular process for manufacturing the moulding material. In this process 50 a cure station 56 across one or more locations on the surface of the prepreg precursor locally cures the resin. This results in a prepreg comprising processed or cured sections 54 and uncured or unprocessed sections in which the resin is still curable following processing of the moulding material in an in mould lay-up.

(14) FIG. 5 shows a cure of a moulding assembly comprising multiple prepreg layers (50 layers) 100 and the same prepreg (25 layers) in combination with its cured counterpart (25 layers) which are interleaved with the uncured prepreg.

(15) The conventional prepreg assembly 100 is cured by increasing the temperature to a dwell temperature of 80 degrees C. During the dwell period 108, the stack releases its exothermic energy as is evidenced by the increase in assembly temperature with a peak of 140 degrees C. after 3.5 hours. The temperature is then increased to the cure temperature 112 of 120 degrees C. and the assembly is then cured.

(16) The assembly of the invention 102 is cured by increasing the temperature to a higher dwell temperature of approx. 100 degrees C. During the dwell period 110, the stack releases a reduced amount of exothermic energy and this energy is released much sooner after 2.2 hours as is evidenced by the increase in assembly temperature with a peak of 135 degrees C. The temperature is then increased to the cure temperature 112 of 123 degrees C. and the assembly is then cured.

(17) As is evident from this Figure, the cure of an assembly comprising the moulding material of the invention is much quicker and the heat input or energy input which is required to process and cure the material is also reduced.

(18) There is thus provided a moulding material and a method of manufacturing the moulding material which has a reduced exothermic release of heat or energy during the in-mould processing of the material. During the manufacture of the moulding material part of the processing has already taken place which would occur during in-mould processing. This results in a simpler cure schedule, improved performance and quality of the moulded article, greater processing speeds and a reduction of the energy input for in-mould processing of the moulding to form a moulded article.