TEXTILE REINFORCEMENT FOR PULTRUSION AND METHOD FOR THE PRODUCTION THEREOF

Abstract

Textile reinforcement that can be used for the production of composite parts by pultrusion, including a central layer made from glass fibre segments and polyester, and in which, in the central layer, the glass fibre segments are enrobed with polyester, the central layer including a central reinforcement core surrounded by the glass fibre segments enrobed with polyester, at least one fibre-web surface layer forming one of the external faces of the textile reinforcement.

Claims

1-19. (canceled)

20. A textile reinforcement which can be used to make composite parts by pultrusion, comprising a central layer having segments of glass fiber coated with polyester, wherein: the central layer furthermore comprises a central reinforcement core, surrounded by said segments of glass fiber coated with polyester, at least one surface layer of fiber web forms one of the outer surfaces of the textile reinforcement.

21. The textile reinforcement as claimed in claim 20, wherein the glass fiber segments in the central layer are pieces of fiber obtained from rovings of glass thread.

22. The textile reinforcement as claimed in claim 20, wherein the glass fiber segments in the central layer comprise glass threads having a linear weight of 40 to 50 tex (40 to 50 grams per kilometer of thread).

23. The textile reinforcement as claimed in claim 20, wherein the polyester coating the glass fiber segments in the central layer is an unsaturated bisphenol polyester, soluble or insoluble in styrene.

24. The textile reinforcement as claimed in claim 20, wherein the central reinforcement core (6) is formed of fibers structured by weaving, or by a grid, or by longitudinal and transverse threads.

25. The textile reinforcement as claimed in claim 24, wherein the fibers forming the central reinforcement core are continuous glass threads having an individual linear weight of 68 to 272 tex.

26. The textile reinforcement as claimed in claim 24, wherein the fibers forming the central reinforcement core are rovings of continuous glass threads and have a linear weight of the roving of 320 to 1200 tex.

27. The textile reinforcement as claimed in claim 20, wherein it comprises two surface layers of fiber web, forming the two external faces of the textile reinforcement.

28. The textile reinforcement as claimed in claim 20, wherein the surface layer(s) is/are made of polyester, polyamide, or polypropylene, having a melting point higher than that of the polyester present in the central reinforcement layer.

29. The textile reinforcement as claimed in claim 20, wherein, in the central layer, the glass fiber segments have a length of 40 to 120 mm.

30. The textile reinforcement as claimed in claim 20, wherein the glass fiber segments are present in the central layer in a quantity of 150 to 2000 g per square meter.

31. The textile reinforcement as claimed in claim 20, wherein in the central layer the polyester is present in a quantity of 3 to 5% by weight of the glass fibers.

32. A method of fabrication of a textile reinforcement usable in making composite parts by pultrusion, involving the following consecutive steps: a) on top of a conveyor belt moving in the longitudinal direction (I-I), arranging a first web of fibers made of polyester, polyamide or polypropylene, b) cutting rovings of glass fiber and letting them drop onto a first pin roller at the same time receiving a polyester powder, making drop onto said first web placed on the moving conveyor belt a first mixture of segments of glass fiber and polyester powder, the polyester powder being chosen so as to have a melting point lower than that of the fibers making up the first web, c) arranging a reinforcement core of reinforcing fibers on the first mixture of glass fiber segments and polyester powder, d) cutting rovings of glass fiber and letting them drop onto a second pin roller at the same time receiving a polyester powder, making drop onto said reinforcement core of reinforcing fibers a second mixture of glass fiber segments and polyester powder, f) heating the assemblage by passing through an oven so as to melt the polyester powder and ensure its distribution around the glass fiber segments, yet without melting the fibers of the first web (23).

33. The method as claimed in claim 32, comprising, prior to step f), an intermediate step e) consisting in depositing, on said second mixture of glass fiber segments and polyester powder, a second web of polyester, polyamide, or polypropylene.

34. The method as claimed in claim 32, wherein the first web is obtained by carding and has a surface density of 20 to 40 g per square meter.

35. The method as claimed in claim 32, wherein the polyester powder used to make the central layer consists of an unsaturated bisphenol polyester resin, soluble or insoluble in styrene, in a quantity of 3 to 5% by weight of glass fiber segments.

36. The method as claimed in claim 32, wherein the polyester powder has the property of melting when subjected to a temperature of 100° C. for two minutes.

37. The method as claimed in claim 32, wherein the polyester powder is in the form of a dry powder or in the form of a powder emulsion in water.

38. The method as claimed in claim 32, wherein a colored polyester web is used.

Description

DESCRIPTION OF THE DRAWINGS

[0047] Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, given in regard to the enclosed figures, in which:

[0048] FIG. 1 is a schematic side view in longitudinal section of a textile reinforcement according to a first embodiment of the invention;

[0049] FIG. 2 is a schematic view in transverse section of the textile reinforcement of FIG. 1;

[0050] FIG. 3 is a schematic side view in longitudinal section of a textile reinforcement according to a second embodiment of the invention;

[0051] FIG. 4 is a schematic view in transverse section of the textile reinforcement of FIG. 3;

[0052] FIG. 5 is a schematic top view of the textile reinforcement according to any of the preceding figures;

[0053] FIG. 6 is a schematic side view illustrating a device and a method for making the textile reinforcement of FIGS. 1 to 5.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0054] In the embodiment illustrated in FIGS. 1 and 2, the textile reinforcement 1 comprises a central layer 2 based on segments of glass fiber 3 coated with polyester 4. A surface layer 5, of fiber web, forms one of the external faces of the textile reinforcement 1, in the present instance, the lower external face.

[0055] The glass fiber segments 3 are rovings of single-strand thread pieces, having a linear weight of 40 to 50 tex, and oriented in random manner between the longitudinal direction and the transverse direction of the textile reinforcement 1.

[0056] The polyester 4 coating the glass fiber segments 3 is an unsaturated bisphenol polyester, whose melting point is on the order of 100° C., lower than the melting point of the synthetic material composing the surface layer 5.

[0057] The surface layer 5 may be made of polyester, polyamide, or polypropylene, reserving the fact that its melting point is higher than that of the polyester making up the central layer 2. A melting point of the fibers of the surface layer 5 can be, for example, around 250° C.

[0058] The central layer 2 moreover comprises a central core of longitudinal reinforcement 6, which is surrounded on its two principal faces by the glass fiber segments 3 coated with polyester 4.

[0059] In the embodiment illustrated in FIGS. 1 and 2, the central core of longitudinal reinforcement 6 is formed of fibers basically oriented in the longitudinal direction and in the transverse direction of the textile reinforcement 1.

[0060] In order to guarantee good mechanical strength under longitudinal traction, the central core of longitudinal reinforcement 6 basically consists of longitudinal threads. The polyester surrounding the glass fibers ensures a good mechanical strength resisting the transverse deformation of the reinforcement.

[0061] In order to guarantee at the same time a good mechanical strength in the transverse direction of the reinforcement, the central core of longitudinal reinforcement 6 is formed of fibers structured by weaving, or by a grid, thus comprising warp threads and weft threads. The advantage of the grid is that it is more easy and quick to produce than the weaving.

[0062] Preferably, the fibers in the central core of longitudinal reinforcement 6 are secured to each other, by gluing, to facilitate the passage through the pultrusion spinneret when the textile reinforcement 1 is used to make a profiled piece by pultrusion.

[0063] A textile reinforcement 1 according to the invention with central core comprising warp threads and weft threads provides a satisfactory mechanical strength not only in the longitudinal direction but also in the transverse direction, allowing such a textile reinforcement 1 to be used to make profiled pieces of greater width.

[0064] In the second embodiment, illustrated in FIGS. 3 and 4, the elements of the embodiment of FIGS. 1 and 2 are found again. Thus, the central layer 2, the glass fibers 3, the polyester 4, the lower surface layer 5, the central core of longitudinal reinforcement 6 are found. The difference lies in the additional presence of a second surface layer 7 of fiber web forming the second external face of the textile reinforcement 1, namely, the upper surface in the illustrated case.

[0065] The second surface layer 7 can be composed of the same synthetic material as the first surface layer 5.

[0066] At least one of the two surface layers 5 and 7 can itself be colored in the mass.

[0067] As can be seen in FIG. 5 in top view, the textile reinforcement according to the invention can be fabricated in the form of a wide band, extending longitudinally along an elongation axis I-I, and of width L consistent with the manufacturing capacities of the customary apparatus for production of textile reinforcements. For example, the width L may be around 2 to 3 m, while the length along the axis I-I may be much greater, and the reinforcement may be wound on a reel.

[0068] In this figure, the fact is illustrated that the textile reinforcement 1 can then be sliced longitudinally along the dotted lines to form bands 1a, 1b, 1c, 1d, 1e, 1f, 1g, and 1h, each of them constituting a pultrusion reinforcement to make a profiled piece.

[0069] Now considering FIG. 6, which represents schematically a device for the fabrication of a textile reinforcement 1 according to the present invention and at the same time illustrates the method of fabrication of the textile reinforcement 1.

[0070] The device 10 represented in this figure comprises a conveyor belt 11, for example in the form of a conveyor band moving between an entry roller 12 and an exit roller 13 in a longitudinal direction I-I as shown by the arrow 14. Near the entry roller 12, above the conveyor belt 11, there is located a first distributor of glass fiber rovings 15 which can deliver glass fiber rovings 16 to a first chopper 17. The pieces of glass fiber rovings 18 emerging from the first chopper 17 are sent to a first pin roller 19 which breaks up the pieces of glass fiber rovings to produce glass fiber segments 20. At the same time, a first powder distributor 21 distributes a polyester powder on the first pin roller 19, which first pin roller 19 at the same time accomplishes the mixing of the powder with the glass fiber segments 20.

[0071] Upstream from the first pin roller 19 there is provided a first web distributor 22 to generate a first web 23 and to arrange it on the conveyor belt 11.

[0072] Furthermore, downstream from the first pin roller 19, there is provided a core distributor 26, which arranges a reinforcement core 27 on the first mixture of fiber segments and powder already present on the conveyor belt 11.

[0073] Downstream from the core distributor 26 there is provided a second distributor of glass fiber rovings 28 which delivers ravings of glass fiber 29 to a second chopper 30, which itself delivers pieces of glass fiber ravings 31 to a second pin roller 32, which itself breaks up the pieces of glass fiber ravings and mixes them with a polyester powder received from a second powder distributor 33 and lets them drop onto the longitudinal reinforcement core 27, forming a second mixture.

[0074] Downstream on the conveyor belt 11 there is provided an oven 24 able to heat the elements placed on the conveyor belt 11, and downstream from the oven 24 there are one or more pressing rollers 25 able to press the materials moving on the conveyor belt 11.

[0075] The oven 24 can be adjusted for example to a temperature of around 180° C., and the speed of movement of the conveyor belt 11 can be such that the heating produced by the oven 24 is sufficient to melt the polyester powder, yet low enough to prevent a melting of the other components of the reinforcement.

[0076] Thus, during the fabrication of the textile reinforcement 1 by the device 10, a first polyester web 23 is arranged on top of the conveyor belt 11 moving in the longitudinal direction I-I. With the first chopper 17, ravings of glass fiber 16 are chopped and made to drop onto the first pin roller 19, which at the same time receives the polyester powder coming from the first powder distributor 21. The glass fiber segments 20 mixed with the polyester powder drop onto the first web 23, itself having been placed on the moving conveyor belt 11, forming first mixture. The core distributor 26 arranges on the first mixture the longitudinal reinforcement core 27, and then the second chopper 30, the second powder distributor 33 and the second pin roller 32 produce and deposit on the longitudinal reinforcement core 27 a second mixture of pieces of glass fiber ravings and polyester powder. During the passage through the oven 24, the polyester powder melts and is distributed around the glass fiber segments. The pressing rollers 25 encourage the formation of a sheet of constant thickness by pressing the melted powder on the glass fiber segments. The result at the exit of the device is a textile reinforcement 1 according to the embodiment of FIGS. 1 and 2.

[0077] Downstream from the second pin roller 32 there can be provided a second web distributor 34, which supplies a web 35 and places it on the assemblage of components present on the conveyor belt 11. After passing through the oven 24 and the pressing rollers 25, a textile reinforcement 1 according to the embodiment of FIGS. 3 and 4 is obtained.

[0078] As a preferred example, the polyester powder may be an unsaturated bisphenol polyester resin. Such a powder is a commercially available product, for example, from COIM SPA with the reference FILCO 661.

[0079] Alternatively, the polyester powder may be an unsaturated bisphenol polyester resin used in an aqueous emulsion, such as the ones commercially available from COIN SPA with the references FILCO 657 or FILCO 659. Its drying temperature is 170 to 200° C. for 40 to 70 seconds. After cross linking, it becomes insoluble in styrene and acquires its bonding ability.

[0080] The present invention is not limited to the embodiments which have been explicitly described, and instead it includes the different variants and generalizations thereof contained in the scope of the following claims.