FR2664349A1 - SEAL SEAL. - Google Patents

Abstract

Seal of the type intended to provide a seal between two facing parts by being housed in a groove formed in one of the parts and produced at least in part by molding a mixture containing, as basic component, an elastomer, as well as the usual fillers and additives and being substantially the same color as the part comprising said groove. The mixture contains a product that is fluorescent under ultraviolet light illumination and is chemically stable at temperatures of at least 200 ° C and pressures of at least 500 kg per cm2, said product being contained in the mixture in a proportion of between 0.1 and 3% by weight of the basic elastomeric component.

Description

The present invention relates to a seal of the type intended

  to achieve a seal between two parts facing each other while being

  housed in a groove in one of the rooms.

  Many types of such seals are known for producing both static seals when the two parts facing each other are fixed and clamped against each other (housing and cover for example) or dynamic seals when one of the parts is mobile, in particular in rotation or in translation relative to the other, (for example a tree in

  a housing bore or a piston in a cylinder.

  These seals can have many forms of section such as circular (O-rings), polygonal, X etc. An example of such a seal providing a static seal and having a quadrangular sectional shape is illustrated in the patent

  FR-A-89 02980 of the applicant company.

  These seals are usually made by molding a mixture having as basic component an elastomer and various conventional fillers and additives, in particular providing functions of initiator and activator of vulcanization, protective functions with respect to the oxidation and functions to impart to the formed joint

good mechanical properties.

  To this latter effect, a greater or lesser proportion of carbon black is usually used which is known to give excellent properties with respect to strength and elongation at

  the rupture of the formed seal.

  The carbon black is present in the molding mixture in proportions which, in practice, may be between

  and 130% by weight of the elastomeric base component.

  The presence of carbon black gives the seal

got a black coloring.

  However, in common practice, particularly in the automotive industry, the seals are delivered to the manufacturer by being premounted on the part provided with the seal receiving groove, the manufacturer having only to realize the assembly of this piece with the piece opposite, this assembly then being sealed due to the presence

of the seal.

  Increasingly, plastic parts are being used and it now happens in many cases that the seal is pre-assembled in a black plastic part, so that when the parts are assembled, the manufacturer does not can be easily realized by a simple visual check of the presence or absence of the seal which 1 - may have been omitted as a result of a handling error, or could possibly be released from the groove of the corresponding part then

  previous operations of handling and transport.

  This is particularly the case in the automotive industry for engine head cover gaskets o the seal is delivered

  preassembled in the plate forming head cover.

  The idea of using clear colored pigments in the molding mixture is not easily conceivable in practice in the measure o given the relatively large amount of carbon black, the seal obtained remain black and the color contrast effect could not be obtained with respect to the black color piece in

which it must be mounted.

  The present invention relates to a seal made by molding a mixture based on elastomer, able to be housed in a groove of a part having substantially the same color as the seal, and which can be easily and easily. quickly identified, even when mounted in

the room.

  The seal according to the invention is at least partly made by molding a mixture containing as base component an elastomer, as well as usual fillers and additives, and is characterized essentially by the fact that said mixture contains a fluorescent product in ultraviolet light and chemically stable light at temperatures of at least 2000 C and pressures of at least 500 kg / cm 2, said product being contained in the mixture in a proportion of

  between 0.1 and 3% by weight of the basic elastomeric component.

  Thanks to the presence of this product emitting a fluorescence in ultraviolet light illumination, it is sufficient to illuminate the assembly consisting of the part and the seal mounted in the groove thereof in ultraviolet light to immediately note the presence or the Absence of

  fluorescence characterizing the presence or absence of the joint.

  The seals according to the invention can be made both by injection molding and by compression molding. When a solid molding mixture is used, it is preferable to use a fluorescent product in ultraviolet light illumination also in the solid state generally in the form of a powder.

Room temperature.

  It is thus possible to use for this purpose in particular 2, 5 bis (5'-tert-butyl-benzoxazolyl (2)) thiophene 2 - However, any product emitting fluorescence in ultraviolet light illumination and stable under the molding conditions, that is to say, especially at temperatures of the order of 200 ° C. and

  pressures of the order of 500 kg / cm 2 can be used.

  Thus it is possible to use, for example, an aminotriazine-formaldehyde sulfonamide co-condensate or the compound of formula:

X O CH = CH CH = CH

OCH 3 H 3 CO

  The basic elastomer component of the molding mixture may be in particular any natural or synthetic rubber used for the manufacture of seals, such as in particular the elastomer

  hydrogenated nitrile known under the trade name THERBAN.

  The seal according to the invention can of course

  be of a type with or without a reinforcement.

  The seal according to the invention may also be of a bi or multi-material type, in which case the seal may be only partially made with the elastomer mixture containing the product.

  fluorescent in ultraviolet light.

  The part comprising the groove housing the seal may be advantageously made of plastic but may also be made of

  other materials, especially metals (aluminum for example).

  Although the invention has been described in connection with particular chemicals, these are given by way of examples in no way limiting In particular the invention is not limited to black colored joints housed in throats of pieces of

black color.

3 -

Claims (3)

1 of the type intended to seal between two parts facing being housed in a groove in one of the parts and made at least in part by molding a mixture containing, as a component of base, an elastomer, as well as usual fillers and additives and being substantially of the same color as the part comprising said groove, characterized in that said mixture contains a fluorescent product in ultraviolet light illumination and chemically stable at temperatures of at least 200 ° C and pressures of at least 500 kg per cm 2, said product being contained in the mixture in a proportion of between 0.1 and 3% by weight of the elastomeric base component.  2 seal according to claim 1, characterized in that the fluorescent product in ultraviolet light illumination is introduced into the mixture in the solid state, in particular in the form of powder. 3 Seal according to any one of   claims I and 2, characterized in that the fluorescent product   ultraviolet light illumination is: 2,5 bis (5 'ter-butyl-benzoxazolyl (2)) thiophene 4 Gasket according to any one of   preceding claims, characterized in that the component   The base elastomer of the blend is a hydrogenated nitrile elastomer.   Seal according to any one of   Claims 1 to 4, characterized in that the molding mixture contains carbon black.   6 Use of the seal according to any one of   of the preceding claims as a motor cylinder head cover gasket motor vehicle.   7 Use according to claim 6, characterized in that the seal is pre-assembled in a groove plate forming a headlamp   8 -Use according to any one of claims 6   and 7 of the seal according to claim 5, characterized in that the   plate forming head cover is black. 4 -