FR2566315A1 - PROCESS FOR MANUFACTURING CARBON FIBER REINFORCED ELASTOMER PARTS - Google Patents

Abstract

A.PROCESS OF MANUFACTURING PARTS IN ELASTOMER REINFORCED BY CARBON FIBERS. B. PROCESS CHARACTERIZED IN THAT IT IS SHAPED BY A MULTIFILAMENT CARBON WIRE CONTAINING AT LEAST 40,000 FILAMENTS WHICH IS COATED WITH A LATEX DISPERSION, THE COATED WIRE IS DRIED, CUT IN SEGMENTS OF 1 TO 20MM LONG AND, BY SWIRLING IN A CURRENT OF AIR, A CLUSTER OF FIBER SEGMENTS FORM; THE FIBER CLUSTER IS MIXED WITH AN ELASTOMER AND THE MIXTURE IS ROLLED INTO A FLAT STRUCTURE.

Description

1.- "Process for manufacturing reinforced elastomer parts

by carbon fibers. "

  The invention relates to a method for producing flat parts made of elastomer reinforced by

carbon fibers.

  Carbon fibers prepared almost ex-

  clusively by pyrolysis of polymers under

  form of fibers, are used above all as reinforcements

  synthetic resins such as epoxy resins,

  polyesters or polyamides. Synthetic resins reinforced with carbon fibers present9 for a specific mass lower than that of materials

  metal, mechanical strength and rigidity

  and, as a result, 9 these are materials that are

  recommended in the construction of vehicles,

  for example space, air and land vehicles.

  Carbon fibers are also used as replacements

  asbestos cement for joints and fittings to

  which often contain an elastomer such as

  trice. The most important base fibers of carbon fibers are polyacrylonitrile and pitch or tar fibers. By heating the fibers to about 200

  at 300 ° C., generally in an oxidizing atmosphere, the

  raw materials are crosslinked or thermally stabilized

  while retaining the fibrous form Stable fibers

  2. - lized are infusible, and will be referred to in the following as carbon fibers as fibers

  completely pyrolyzed, containing exclusively

  bone. Cross-linking and pyrolysis produce heat-resistant fibers with mechanical strength and

  rigidity, which can in principle be trans-

  formed like other textile fibers. The breaking ability and the low resistance to bending are here

  a disadvantage, and a difficulty which makes it very difficult

  manipulation and processing as textile fiber.

  tile. We know the possibility of improving the maneuverability

  carbon fibers by applying a primer. Contrary

  to the applications usually practiced on other

  In the case of textile fibers, the application of approvals causes problems here if the coated fibers have to be incorporated in a matrix. The finishes must at least not compromise the adhesion of the fibers to the matrix, but improve it as much as possible. is to say that they must be compatible with matrices? Of course,

  there is no primer that allows for textile shaping

  satisfactory carbon fiber and which is also

  if compatible with all usual matrix systems

  technically necessary in the industry.

  this, we know only the primers that fill these

  conditions for one or for some matrices. For example

  plep the diglycidylether-coated carbon fibers of the

  bisphenol A adhere well to an epoxy resin matrix.

  of, but insufficiently on a terephthalate matrix of

  polybutylene (US Patent 4,364,993). For thermal resins

  In particular, such polycarbonates or polyamides, it should be advantageous to apply polyurethane solution and dispersion coatings (DE-OS 33 02 012). These known primers cited as exem

  ple, and others, are not, however, suitable for

  to form carbon fibers in an elastomer matrix

  39 - mother. Thin elastomer parts that can be converted into gaskets, clutch

  for this purpose, include carbon fibers

  as reinforcing material, generally in a non-uniform distribution and bond in the elastomer matrix, so that the properties of the products only partially and not always meet the application conditions. objective of improving the known processes for the manufacture of

  thin elastomer products containing

  bone, especially the handling of carbon fibers,

  to reduce the number of fiber breaks in

  during the production of the composite

  site, evenly distribute the fibers in the matrix

  of elastomer and bind them firmly to the matrix.

  For this purpose, the invention proposes a process characterized in that: a) a multifilament carbon thread is formed comprising

  at least 40 000 filaments, which is coated with a

  latex yarn, the coated yarn is dried, cut into segments

  from 1 to 20 mm long and 9 by swirling in

  a stream of air, a cluster of

bers,

  b) the pile of fibers is mixed with an elastomer and the mixture

  ge is processed by rolling into a flat structure.

  The product obtained is then converted into gaskets and

brakes or clutch.

  To achieve the object of the invention, it is necessary to first coat the carbon fibers with a matrix-compatible primer and then dispose the coated fibers into a loose pile. The coating of

  viscose and polyamide fibers and, after a

  special preliminary treatment, also of polyester and aramid, with latex dispersions, and the incorporation of the 4, - fibers coated in the elastomer as well as the adhesion

  improved fibers thus treated in the disordered matrix.

tomère, are known,

  In view of the fundamental behavior

  different from the carbon fiber surface, the specialist could not expect the fibers to

  carbon coated with latex, behave in the same way

  in particular, that the rigid fibers coated are not broken or destroyed by incorporation into the elastomer mass. This effect

  However, this is only achieved if the carbon fibers in

  picks are heaped together by swirling in a stream of air. Without the formation of a loose pile, it is also not possible to evenly distribute the fibers in the elastomer matrix. The carbon fibers are coated with an aqueous dispersion of latex, preferably a dispersion.

  further containing a butadiene-styrene copolymer

  vinylpyridine, whose adhesion is somewhat superior.

  It is also advantageous to add to the dispersion a pre-

  Resorcinol-formaldehyde condensate, which contains both substances

  in a ratio of 10 o. 1 to 2 O 1o The content of the dispersion

  precondensate must not be greater than 10% q because with higher contents9 the filaments of the

  could fit together. In accordance with the nomencla-

  In use, the term elastomer refers to natural and synthetic materials whose transition temperature for the vitreous state is less than 000 and lower than the temperature of use, in particular, natural and synthetic rubber. Carbon threads used to reinforce elastomers - including thermally stabilized fiber yarns - must contain at least 40,000 filaments, because homogeneous distribution is not possible with yarns where the number of filaments is smaller. The yarns are preferably drawn by passing through a trough filled with latex dispersion and passing for drying in a drying channel or oven, and

  Coated wires are cut into segments 1 to 20 mm long.

  For the cutting of yarns, all the tools used in the preparation of short fibers are suitable, for

  example the "bars" cutting or rotating blades.

  The fiber segments are then subject to a vortex

  in a stream of air and separates a pile of

  in a filter or a cyclone, with a specific gravity

  bulk of 20 to 200 g / il preferably. The length of the segments

  fiber densities and the density of the fiber pile are de-

  terminated separately by the use of the fiber reinforced elastomer mass, and may be evaluated by simple prior testing. Generally, the length of the fibers taken in the cluster is between 0.5 and 20 mm, and the bulk density between 20 and 200 g / l. The pile of fibers is incorporated into the elastomer matrix using a

  conventional forced-blending kneader, and the mixture is trans-

  formed by rolling into a thin product, the proportion of

  fibers is a function of the application of the elastic part

  tomère; for friction linings, it will be 5 to 20%, and for seals, greater than%. The invention will be better understood with the aid of the following example. A thermally stabilized polyacrylonitrile multifilament yarn comprising 32,000,000 filaments, a titer of 42 ktex and a density of 1.40 g / cm 3 is coated with an aqueous dispersion of latexo Composition of the dispersion: free water 61.5% ammonia 0Q2 copolymer latex dispersion 30 (proportion of butadiene-butyrene-vinylpyridine fibers 40%) resorcinol-formaldehyde precondensate 893 (proportion of solid matter 30%) 6.- The dispersions mentioned are: products

of commingce.

  The multifilament yarn is pulled through a trough filled with dispersion; the dimmersion time is about 1 minute. The coated yarn is heated to room temperature and at about 130 to 140 C in a

  drying channel, cut from a cutting mill in seg-

  3 to 10 mm long and swirled in a stream of air. The pile of fibers that separates in a cyclone with a bulk density of about 50 g / l is

  incorporated into chloroprene rubber in a mala-

  forced mixing and the mixture is charged with

and a vulcanizing agent.

  Composition Chloroprene rubber 20% coated fiber 18 iron oxide 15 magnesium oxide 15 talc 15 calcium hydroxide 10 graphite 5 sulfur 1 zinc oxide 1

  The mixture was granulated and pressed, by

  buffer, at about 16000 C and under a pressure of 20 MPa,

  in flat discs that have been subjected to post-vulcaniza-

  at about 1800 ° C. in a circulating air oven. Microscopic study of discs intended to act as friction linings for disc brakes.

  and drum brakes, has shown that, for a proportion

  preponderance of stabi- lized polyacrylonitrile fibers

  thermally, the fibers have not been reduced

  In lengthwise mixing and forming of the elastomer mass, it also showed the homogeneous distribution of the fibers in the matrix and the very good bonding of the fibers in this matrix. Similarly, the dispersion of the wear and the braking effect (retardation) measured

on a test bench, was weak.

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Claims (5)

REVEND I C A T I 0 NS   1.- Method of manufacturing flat parts   made of elastomer reinforced with carbon fibers,   in that: a) a multi-carbon carbon wire is formed comprising   at least 40,000 filaments9 which is coated with a   Latex persion, the coated wire is dried, cut into segments 1 to 20 mm long and, by swirling in a stream of air, a cluster of fiber segments is formed,   b) the pile of fibers is mixed with an elastomer and the   The lange is rolled into a flat structure.   2. Process according to claim 1, camisole   characterized in that a latex dispersion formed from a copolymer   butadiene-styrene-vinylpyridine mother is used,   3. Process according to any one of the   1 and 2, characterized in that a dispersion of   latex containing a resorcinol-formaldehyde pre-condensate is Lisée.   4. Process according to any one of the   1 to 3, characterized in that dispersions   with a pre-condensate content of 2 to 10% are used   Sees. Process according to any one of Claims 1 to 4, characterized in that a pile of fibers having a bulk density of 20 to 200 g / l is formed. 6. Process for the production of flat parts elastomer reinforced with carbon fibers, according to   any of claims 1 to 5, characterized in that   what the parts obtained are used as seals flat sealing.   7.- Process for manufacturing carbon fiber reinforced elastomeric flat parts according to   any one of claims 1 to 55 characterized in   the parts obtained are used as friction linings,