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WO1989003759A1 - Materiau composite - Google Patents

Materiau composite Download PDF

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Publication number
WO1989003759A1
WO1989003759A1 PCT/GB1988/000931 GB8800931W WO8903759A1 WO 1989003759 A1 WO1989003759 A1 WO 1989003759A1 GB 8800931 W GB8800931 W GB 8800931W WO 8903759 A1 WO8903759 A1 WO 8903759A1
Authority
WO
WIPO (PCT)
Prior art keywords
yarn
composite material
fabric
knitted
fibres
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/GB1988/000931
Other languages
English (en)
Inventor
Dennis John Williams
Gerald Francis Day
Frank Robinson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Akzo Nobel UK PLC
Original Assignee
Courtaulds PLC
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 Courtaulds PLC filed Critical Courtaulds PLC
Publication of WO1989003759A1 publication Critical patent/WO1989003759A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • B29C70/06—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
    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
    • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
    • D02G3/22—Yarns or threads characterised by constructional features, e.g. blending, filament/fibre
    • D02G3/34—Yarns or threads having slubs, knops, spirals, loops, tufts, or other irregular or decorative effects, i.e. effect yarns
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04B—KNITTING
    • D04B1/00—Weft knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes

Definitions

  • This invention relates to a composite material reinforced with knitted fabric.
  • a composite material having improved strength comprises a matrix material reinforced by a fabric of knitted yarn embedded within the matrix material characterised in that the yarn has a main body and surface fibres which project laterally from the main body which fibres project into the regions of matrix material located within the knitted loops of yarn so as to reinforce those regions.
  • the surface fibres of the yarn may be in the form of fibres having free ends at the extremity of projection or in the form of filament loops.
  • the terms "fibres” and “filaments” are used interchangeably except where the context requires otherwise.
  • the yarn is preferably of the core/effect type but may also be a spun yarn having a hairy surface.
  • Suitable core/effect yarns include texturised continuous filament yarns, particularly air-texturised yarns having an effect portion in the form of projecting filamentary loops, boucle yarns, knop yarns and other yarns of the so-called fancy effect type.
  • the proportion by weight of the projecting surface fibres is preferably at least 10 per cent and more preferably at least 30 per cent of the total weight of the yarn.
  • a preferred range, particularly for core/effect yarns, is for the projecting surface fibres to be 40 to 60 per cent by weight of the yarn with the main body (or core in a core/ effect yarn) making up the difference.
  • the improvement in strength possessed by the composite material of the invention compared with a composite knitted from a flat (i.e. untexturised) continuous filament yarn is believed to derive from the reinforcement of the resin-rich regions enclosed by the yarn loops.
  • This reinforcement is provided by the surface fibres projecting into those regions from the main body of the yarn constituting the knitted loops. Crack propagation which can proceed unchecked across resin-rich regions can be stopped or minimised because any path which a crack might follow without meeting a fibre can be made tortuous rather than straight by the presence of the fibres.
  • Improved results in this regard are obtained if the surface fibres are of sufficient length that when they project into the region within the knitted loops there is overlapping of fibres projecting from adjacent or opposite parts of the knitted loops.
  • the yarn preferably comprises high strength fibres or filaments made from one or more of the materials comprising carbon, aromatic polyamides, silicon carbide, ceramics and glass.
  • Core/effect constructions in which the effect portion is combined with the core portion during yarn manufacture or processing allow the use of different filaments or fibres in the respective portions.
  • the core portion may be of high strength filaments and the effect portion of high strain filaments to give a balance of properties in the composite material.
  • the matrix material may be of any suitable material including a thermosetting resin, a thermoplastics resin, carbon or a ceramic material.
  • Suitable thermosetting resins include epoxy, polyester and phenolic resins.
  • the matrix material of the composite material according to the invention may incorporate particulate or short fibre fillers including talcum powder, silica powder and rubber or glass microspheres
  • the composite material of the invention may be further improved by knitting the fabric in a structure which produces lengths of unlooped float yarn in the fabric.
  • weft knitted fabric such floats can be produced in the course direction, for example, as in a cross float jersey tuck fabric. It is also possible to lay in additional yarns along the course direction with weft knitted fabrics or along the wale direction in the case of warp knitted fabrics. Both of these techniques can give considerable improvements in strength in the direction of the float or of the laid-in yarn. However, this can be at the expense of a balance of strength properties in the wale and course directions of the fabric which balance is desirable when the composite material is required to have isotropic properties.
  • Another technique which can be employed to vary the strength of the composite material in the wale and course directions of the fabric is to vary the shape -of the knitted loops.
  • the usual elongated loop structure produces greater wale strength then course strength.
  • Course strength can be improved by changing the shape of the loops so that their width is increased at the expense of their height. This change in shape tends to occur when using the bulky, surface effect yarns employed according to the invention. These yarns also make it possible to control loop shape to suit the desired balance of properties.
  • a process for making a composite material by knitting a fabric from yarn and embedding that fabric in a matrix material as reinforcement therefor is characterised by knitting the fabric from a yarn having a main body and surface fibres which project laterally from the main body, tensioning the fabric during the knitting process and/or subsequently to produce knitted loops of the desired shape for optimum reinforcement and maintaining that desired shape during subsequent processing into the composite material by the inter-engagement of the surface fibres projecting from adjacent portions of yarn.
  • Tensioning during the knitting process may be varied by the tensioning effect of the fabric draw-down rollers.
  • the pressure of the presser foot can also be controlled.
  • tensioning of the fabric longitudinally will increase the length of the loops to give greater wale direction strength to the composite material.
  • Lateral tensioning for example by stretching the fabric out on a stenter, can be employed to widen the loops and improve course direction strength.
  • the use of the yarn as specified according to the invention allows the fabric to be maintained in the desired loop configuration whilst it is being processed into a composite material. This is made possible because the fibres projecting from the main body of the yarn inter- engage and thereby hold adjacent portions of yarn in the set position. This effect promotes general stability of the fabric and facilitates handling in assembly operations involved in the manufacture of composite structures. The effect is especially marked when the projecting surface fibres are in the form of loops.
  • Weft knitting particularly employing a machine with a presser foot facility, can be used to produce three- dimensionally shaped structures which can constitute a pre-for of a composite structure.
  • the use of the specified yarn to knit such structures facilitates handling of the shaped structure and helps to maintain it in the desired shape during incorporation in the matrix material.
  • Figure 1 shows diagrammatically the configuration of two knitted loops in a composite material
  • Figure 2 is an enlarged section on the line A-A of Figure 1 extended to show links of a loop of yarn adjacent to that shown in Figure ___. ,
  • Figure 3 is a diagrammatic representation of two interconnected loops of a fabric knitted from yarn having surface fibres projecting in the form of loops, and
  • Figure 4 is a diagram including a graph, illustrating the variation in fibre concentration in a region such as that of the section A-A in Figure 1, plotted against displacement across the region.
  • micrographs of composite materials reinforced with knitted fabric have been obtained which correspond closely with Figure 2 and show that crack propagation in the composite material tends to follow a line such as the broken line 7, passing round the fibre reinforcement 8, in this case a yarn, and extended straight across resin-rich regions 5 and 10.
  • the strength of the composite material can be considerably improved. Crack propagation in pure resin regions requires less energy than where fibres are present to act as reinforcement.
  • a yarn 12 as specified according to the invention is used to knit the reinforcing fabric, as shown in Figure 3, the strength of the resulting composite material will be increased.
  • the projecting fibres, projecting from the main body 11 of the yarn are in the form of loops 13 of filaments such as would be produced in a core/effect, air-texturised continuous filament yarn or a boucle yarn.
  • FIG 4 shows a graph of fibre concentration (as defined above) along the y-axis against the distance moved along the x-axis by the element of volume used to determine the fibre concentration.
  • the variation in fibre concentration is illustrated in relation to the two limbs 14 and 15 of the head of a knitted loop along the section shown in the upper part of Figure 4 (i.e. a section such as the section A-A in Figure 1).
  • Flat, untexturised continuous filament yarn will produce a fibre concentration curve such as that indicated by reference numeral 16.
  • a yarn as specified according to the invention will result in a curve such as 17 and, if a sufficient proportion of surface fibres project from the main body of the yarn, the curve 17 may be modified by the introduction of the portion 18 shown in dotted line. This may be produced by the effect of the overlapping of the surface fibres projecting from the two limbs 14 and 15 of the knitted loop into the region between them.
  • filaments in the main body of the yarn for example the core portion or a proportion of it in a core/effect yarn
  • the laterally projecting surface fibres in the yarn may advantageously be a high strain fibre, preferably having a greater strain to break than the matrix material of the composite material.
  • High tensile strength filaments in the body of the yarn may, of course, advantageously be combined with high strain filaments projecting laterally from the main body, for example in loop form.
  • the invention is illustrated by the following Example.
  • Two fabrics A and B were knitted in the same construction on a 5 gauge flat bed knitting machine having a presser foot facility. Both fabrics were knitted using continuous filament glass yarns of 1660 overall decitex comprising individual filaments of 6 microns diameter.
  • the yarn used to make fabric A which was the control fabric, was a flat, untexturised yarn whereas the yarn used to make fabric B was an air-texturised yarn made using a "Taslan" (Registered Trade Mark) type of air-texturising jet.
  • the latter yarn comprised a core portion of essentially straight filaments from which projected an effect portion comprising loops of filaments projecting laterally from the core portion.
  • the effect or loop portion of this yarn constituted 57 per cent by weight of the total yarn weight.
  • the fabric construction of both fabrics was a weft knitted double jersey construction in which the two layers of jersey were joined by a tuck stitch. Each jersey layer was knitted using three yarn feeds with the yarns knitting on successive needles so that each yarn knitted on every third needle and floated across the two intermediate needles in a so-called 2 1 cross float jersey structure.
  • Fabric A had a weight of 1,800 gms/sq.metre and fabric B had a weight of 1,413 gms/sq. metre.
  • Composite materials were made using each of fabrics A and B by pouring a thermosetting resin onto the respective fabrics and working the resin into the fabrics manually.
  • the resin used was an epoxy resin made by Ciba-Geigy Limited coded LY 1927 GB with hardener HY 960.
  • a and B respectively, two plies of resin-impregnated fabric were placed with their wales in alignment in a compression press pre-heated . to a temperature of 60°C. and compressed to squeeze out excess resin. The resin was then allowed to cure over 9 minutes to produce a 3 mm thick plate of composite material having a volume fraction of glass fibres of 50 per cent in the case of fabric A and 45 per cent in the case of fabric B. Rectangular test samples were cut from each of the plates some with the fabric wales in alignment with the long edges of the samples and some with the fabric courses in such alignment. The samples were then tested using an Instron apparatus for tensile strength and tensile modulus according to the test method ASTM/D/3039 and for flexural strength and flexural modulus according to the test method ASTM/D/790.
  • test results for the composite material made using fabric A show the usual pattern for knitted fabric reinforcement of higher strength and modulus in the wale direction compared with the course direction. This produces an anisotropic composite material. This pattern is maintained despite the use of a knitting construction which produces float yarns in the course direction.
  • test results for the composite material made using fabric B show a reversal of the usual pattern, with higher strengths in the course direction then in the wale direction.
  • the tensile and flexural strengths in the course direction are substantially increased and there is a comparative fall in tensile and flexural strengths in the wale direction which brings the strengths in the two directions more into balance.
  • Tensile and flexural modulus is affected in the same way to produce a very good balance of modulus between the wale and course directions.
  • Industrial Applicability T h is invention finds application in the field of composite materials reinforced by fabrics of knitted yarn.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Knitting Of Fabric (AREA)

Abstract

Un matériau composite présentant une résistance accrue comprend un matériau matriciel (5) renforcé par un tissu de fil tricoté (12) incorporé dans le matériau matriciel (5). Le fil (12) comporte des fibres de surface (13) qui s'étendent latéralement depuis le corps principal (11) dans des régions (5, 10) du matériau matriciel situées à l'intérieur de boucles tricotées (6) du fil, de façon à renforcer ces régions.
PCT/GB1988/000931 1987-10-30 1988-10-28 Materiau composite Ceased WO1989003759A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8725470 1987-10-30
GB8725470A GB8725470D0 (en) 1987-10-30 1987-10-30 Textured composites

Publications (1)

Publication Number Publication Date
WO1989003759A1 true WO1989003759A1 (fr) 1989-05-05

Family

ID=10626185

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1988/000931 Ceased WO1989003759A1 (fr) 1987-10-30 1988-10-28 Materiau composite

Country Status (2)

Country Link
GB (1) GB8725470D0 (fr)
WO (1) WO1989003759A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991015619A1 (fr) * 1990-03-30 1991-10-17 Courtaulds Plc Armature et structure renforcee
US5395684A (en) * 1991-01-23 1995-03-07 Courtaulds Aerospace Limited Thermal insulation materials
WO2002057067A1 (fr) * 2001-01-19 2002-07-25 Bae Systems Plc Composites
EP4089217A1 (fr) * 2021-05-10 2022-11-16 Pai Lung Machinery Mill Co., Ltd. Procédé de tricotage et de formation de tricot à mailles cueillies d'épaisseur variable par une tricoteuse rectiligne et tricot à mailles cueillies correspondant

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB747726A (en) * 1953-02-10 1956-04-11 Polychemical Developments Ltd Improvements in or relating to the manufacture of reinforced plastic material
US3323975A (en) * 1965-07-06 1967-06-06 Owens Corning Fiberglass Corp Resinous coated glass fiber yarn and fabric woven therefrom
GB1212396A (en) * 1968-02-13 1970-11-18 Gen Technologies Corp A high shear-strength fiber-reinforced composite body
US3551269A (en) * 1967-03-06 1970-12-29 Owens Corning Fiberglass Corp Glass fiber-plastic composites of improved strength
FR2160998A1 (fr) * 1971-11-24 1973-07-06 Du Pont
US3808087A (en) * 1967-09-26 1974-04-30 Gen Technologies Corp Surface-treated lamination structures
EP0035904A2 (fr) * 1980-03-12 1981-09-16 Arthur Murray Reader Etoffes secondaires de renforcement pour tapis
WO1987003250A1 (fr) * 1985-11-22 1987-06-04 Peabody Abc Corporation Tissu tricote en chaine et a insertion de trame, et feuille plastique renforcee avec ce tissu

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB747726A (en) * 1953-02-10 1956-04-11 Polychemical Developments Ltd Improvements in or relating to the manufacture of reinforced plastic material
US3323975A (en) * 1965-07-06 1967-06-06 Owens Corning Fiberglass Corp Resinous coated glass fiber yarn and fabric woven therefrom
US3551269A (en) * 1967-03-06 1970-12-29 Owens Corning Fiberglass Corp Glass fiber-plastic composites of improved strength
US3808087A (en) * 1967-09-26 1974-04-30 Gen Technologies Corp Surface-treated lamination structures
GB1212396A (en) * 1968-02-13 1970-11-18 Gen Technologies Corp A high shear-strength fiber-reinforced composite body
FR2160998A1 (fr) * 1971-11-24 1973-07-06 Du Pont
EP0035904A2 (fr) * 1980-03-12 1981-09-16 Arthur Murray Reader Etoffes secondaires de renforcement pour tapis
WO1987003250A1 (fr) * 1985-11-22 1987-06-04 Peabody Abc Corporation Tissu tricote en chaine et a insertion de trame, et feuille plastique renforcee avec ce tissu

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991015619A1 (fr) * 1990-03-30 1991-10-17 Courtaulds Plc Armature et structure renforcee
US5395684A (en) * 1991-01-23 1995-03-07 Courtaulds Aerospace Limited Thermal insulation materials
WO2002057067A1 (fr) * 2001-01-19 2002-07-25 Bae Systems Plc Composites
EP4089217A1 (fr) * 2021-05-10 2022-11-16 Pai Lung Machinery Mill Co., Ltd. Procédé de tricotage et de formation de tricot à mailles cueillies d'épaisseur variable par une tricoteuse rectiligne et tricot à mailles cueillies correspondant

Also Published As

Publication number Publication date
GB8725470D0 (en) 1987-12-02

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