US3842628A - Industrial tapes - Google Patents

Abstract

An industrial tape for reinforcing materials such as laminates and mouldings, comprises a knitted woven or non-woven ground fabric on which a carbon filament tow is held by overlying holding threads. In the case of a knitted ground fabric the overlying holding threads are preferably knitted loops.

Description

man States Patent [191 Bennett et a1.

INDUSTRIAL TAPES Inventors: James Bennett; Ashby Parva, both of Nr. Rugby, England Assignee: Specialized Tapes Limited,

Hinckley, England Filed: Oct. 5, 1972 Appl. No.: 295,337

[30] Foreign Application Priority Data Oct. 28, 1971 Great Britain 50407/71 US. Cl. 66/193, 66/202 Int. Cl D04b 21/14 Field of Search 66/ 190-195, 66/202; 139/420 R, 420 C, 425; 57/140 R,

[56] References Cited UNITED STATES PATENTS 2,800,783 7/1957 Abood 66/192 Primary Examinerlames Kee Chi Attorney, Agent, or Firm-Burgess, Dinklage & Sprung 57 ABSTRACT An industrial tape for reinforcing materials such as laminates and mouldings, comprises a knitted woven or non-woven ground fabric on which a carbon filament tow is held by overlying holding threads. 1n the case of a knitted ground fabric the overlying holding threads are preferably knitted loops.

7 Claims, 9 Drawing Figures u i were k r n n PAIEmnnm 3.842.828

- smuuF-a WA RP I FIG. FIG. FIG. FIG.

2A 28" 2c 20 Y INDUSTRIAL TAPES The invention relates to industrial tapes for the stiffening and reinforcement of materials, in particular plastics, wood and/or metal laminates and matrix materials such as plastics mouldings, and to a method of producing such tapes.

Carbon filaments are a valuable reinforcing material for the manufacture of, for example, reinforced plastics mouldings, and such mouldings comprising carbon filaments in a plastics matrix have a very desirable stiffness to weight ratio. The carbon filaments are preferably laid in the form of a tow which may contain about 10,000 individual filaments and one difficulty in the manufacture of such reinforced mouldings, lies in the handling of the tow.

The invention provides an industrial tape comprising a ground fabric on which is supported at least one carbon filament tow held to the fabric by an overlying holding thread. Preferably the tape is knitted, with the overlying holding thread forming part of the knitted construction. An alternative construction is a woven or non-woven ground fabric on which a carbon filament tow is held by overlying stitches. The ground fabric is preferably made from glass fibre threads, which have physical properties suitable for use themselves as reinforcements in matrix materials. The overlying holding thread is preferably also a glass fibre thread. A number of carbon filament tows may be arranged longitudinally along the tape, each retained by an overlying holding thread. Each carbon filament tow may comprise a single carbon fibre bundle or may be built up from a number of such bundles. For certain applications, for example the reinforcement of fairly large panels such as car bodies and boat hulls, each carbon filament tow preferably stands proud of the plane of the rest of the tape for as great a height as possible. Flattening of a tow by the overlying holding thread can be prevented by reducing the tension of the holding thread, or, in the case of a knitted construction, by increasing the tension of the threads of the knitted ground fabric. For other applications, for example the reinforcement of laminated structures in which the tape is held in a plastics matrix between two sheets that are bonded together by the matrix, the carbon filament tow is preferably substantially flush or nearly as flush as possible with the rest of the tape.

The carbon filament tow may extend axially along the tape or diagonally across the tape in zig-zag formation. The latter provides a reinforcement against torsional stress as well as against longitudinal flexure. Tapes having at least two carbon filament tows one or more of which extends axially along the tape and one or more of which extends diagonally across the tape provide reinforcement against longitudinal as well as torsional flexure and are particularly suitable for the reinforcement of moulded snow skis.

Tapes according to the invention can be knitted on warp knitting machines equipped with warp inlay bars, preferably at least three. A suitable machine would be a single bed raschel knitting machine. The tapes may have a thickness of two or more needles, preferably six needles.

The preferred method of knitting a tape according to the invention with a single carbon filament tow is as follows: each warp needle knits a chain of loops, and a first warp inlay bar shogs reciprocally over two or more needle spacings to lay one or more backing threads to form a ground structure. A second warp inlay bar inserts the carbon filament tow down the ground structure between adjacent needles. If the second warp inlay bar lays in the carbon filament tow without shogging the tow is arranged axially along the tape. If the second warp inlay bar shogs from side to side the tow is arranged diagonally across the tape in zig-zag configuration. A third warp inlay bar shogs reciprocally ever two or more needle spacings to lay the holding thread between the needles on each side of the carbon filament tow. The tension of the backing thread below the carbon filament tow should be increased or that of the holding thread above the carbon filament tow reduced if it is desired that the carbon filament tow should stand proud of the rest of the tape. For example, the holding thread may be laid in at a negligible tension so that it forms an upstanding loop around the carbon filament tow and does not flatten the tow. To knit a tape with more than one carbon filament tow an analogous procedure is used, optionally using more than one holding thread. The knitted structure may if desired incorporate a ladderresist thread formation.

The invention is illustrated by the drawings, of which:

FIG. 1 is a loop diagram of a tape according to this invention; and

FIGS. 2A to 2D are diagrams showing warp chains and the movements of the three warp inlay bars of a single bed raschel knitting machine that would produce the tape of FIG. 1. Only the two needles one on each side of the carbon filament tow are shown in FIGS. 2A to 2D.

FIG. 3 shows the loop diagram of a tape of the invention having a zig-zag carbon tow.

FIGS. 3A to 3C are diagrams showing the movement of the three warp inlay bars of a single raschel knitting machine that would produce the tape of FIG. 3.

Six needles are used to knit the tape. Warp chains shown in FIG. 2A are formed. A chain of loops of glass fibre thread 1 is knitted on each needle, and five glass fibre ground threads 2 are laid around adjacent needles on successive courses (FIG. 2B). The five ground threads 2 are laid by a single warp inlay bar which carries five warp inlay tubes at single needle spacings. A carbon filament tow 3 is inserted from a second warp inlay bar with no bar sideways movement (FIG. 2C). The warp inlay tube feeding the carbon filament tow preferably has a flared inlet to assist insertion of the tow and prevent shredding. A glass fibre holding thread 4 is simultaneously laid from a third warp inlay bar around the needles on each side of the tow 3, shogging the third warp inlay bar through two needle spaces in alternative directions every other course (FIG. 2D). The tension of the holding thead 4 is reduced to a minimum so that it does not flatten the tow 3 but forms an upstanding loop around the tow.

The resulting tape is relatively easy to handle, especially when used in the reinforcement of fairly large mouldings such as car bodies and boat hulls.

I claim:

1. A warp knitted industrial reinforcement tape having a knitted structure comprising:

a. chains of warp-knitted stitches formed of warp threads;

b. at least one backing thread laid into the knitted structure beneath the chains of warp-knitted stitches;

c. at least one carbon filament tow laid into the knitted structure over the chains of warp-knitted stitches; and

d. at least one holding thread laid into the knitted structure over the chains of warp knitted stitches and the carbon filament tow to hold the tow in the ta e.

2. A warp-knitted industrial reinforcement tape according to claim 1, wherein the threads forming chains of warp-knitted stitches, the backing threads and the holding threads are all glass fiber threads.

3. A warp-knitted industrial reinforcement tape according to claim 1, wherein at least one backing thread is at higher tension than the at least one holding thread so that the carbon filament tow stands proud of the plane of the rest of the tape.

4. A warp-knitted industrial reinforcement tape according to claim 1, wherein the backing and holding threads are at substantially the same low tension so that the carbon filament tow lies substantially flush with the rest of the tape.

5. A warp knitted industrial reinforcement tape according to claim 1, wherein the carbon filament tow extends axially along the tape.

6. A warp-knitted industrial reinforcement tape according to claim 1, wherein the carbon filament tow extends diagonally across the tape in a zig-zag configuration.

7. A warp-knitted industrial reinforcement tape according to claim 1, wherein at least two carbon filament tows are held in the tape by the at least one holding thread, one carbon filament tow extending axially along the tape and the other carbon filament tow extending diagonally across the tape in a zig-zag configuration.

" 1:53; UNITED sums IA'USN'LLUI'I'ILE. I CERTIFICATE OF? CORRECTION I Patent No. 4 ,628

Dated October 22, 1974 InventorGO James Bennett It is certified that error appears" in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

For. Inventors:

"James" Bennett; Ashby'Parva, b'oth'of Nr. Rugby, England" should read "James Bennett of Ashby Pa'rva, Nr. Rugby, England".

Signed and sealed this 2 4thday of December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents

Claims (7)

1. A warp knitted industrial reinforcement tape having a knitted structure comprising: a. chains of warp-knitted stitches formed of warp threads; b. at least one backing thread laid into the knitted structure beneath the chains of warp-knitted stitches; c. at least one carbon filament tow laid into the knitted structure over the chains of warp-knitted stitches; and d. at least one holding thread laid into the knitted structure over the chains of warp knitted stItches and the carbon filament tow to hold the tow in the tape.

2. A warp-knitted industrial reinforcement tape according to claim 1, wherein the threads forming chains of warp-knitted stitches, the backing threads and the holding threads are all glass fiber threads.

3. A warp-knitted industrial reinforcement tape according to claim 1, wherein at least one backing thread is at higher tension than the at least one holding thread so that the carbon filament tow stands proud of the plane of the rest of the tape.

4. A warp-knitted industrial reinforcement tape according to claim 1, wherein the backing and holding threads are at substantially the same low tension so that the carbon filament tow lies substantially flush with the rest of the tape.

5. A warp-knitted industrial reinforcement tape according to claim 1, wherein the carbon filament tow extends axially along the tape.

6. A warp-knitted industrial reinforcement tape according to claim 1, wherein the carbon filament tow extends diagonally across the tape in a zig-zag configuration.

7. A warp-knitted industrial reinforcement tape according to claim 1, wherein at least two carbon filament tows are held in the tape by the at least one holding thread, one carbon filament tow extending axially along the tape and the other carbon filament tow extending diagonally across the tape in a zig-zag configuration.

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