FR2718574A1 - Method of sealing an electrical connector and connector thus obtained. - Google Patents

Abstract

The method comprises the operations consisting of: - inserting, into a box-shaped housing (12), the respective ends (18) of several electrical cables (20) and - sealing, by means of a resin (22), the gaps existing between the cables (20) and the walls of the housing (12), this process being characterized by the fact that the resin (22) used is a two-component and crosslinkable resin. The electrical connector can be obtained by implementing this process.

Description

The present invention relates to a method of sealing a connector

  electric motor, intended in particular for use on motor vehicles,

  as well as the connector thus obtained.

  More particularly, the present invention relates to a method comprising the steps of: - inserting the different ends of several electrical cables into a box-shaped casing and - sealing with a resin the interstices between them cable

and the walls of the case.

  The sealing operation must ensure the impermeability of the container to the water in the entire range of temperatures to which it may be

  during its operation, as well as its resistance and its impermeability

  the various fluids used in a motor vehicle, such as fuels, lubricating oils, liquids for the cooling and

brakes and the like.

  In the known art, the sealants used are

  hot-melt polyamide resins which are hot-run in the above-mentioned

  These are then solidified by cooling.

  Such resins have the disadvantage of melting or softening already at

  temperatures below 150 C and therefore not being able to guarantee

  thermal resistance properties that meet the current requirements of

car drivers.

  In order to overcome the aforesaid drawback, the subject of the present invention is a process of the type indicated above and characterized in that the resin

  used is a two-component, crosslinkable resin.

  Such resins also easily withstand temperatures of the order of 150 C and thus fully meet the thermal resistance requirements, while at the same time having good resistance to fluids commonly used in

the automotive field.

  Preferably, the resins used in accordance with the invention are

  amino-epoxy type, and more preferably of the polyurethane type.

  The essential characteristics of these resins lie in the fact that they polymerize rapidly by crosslinking (at most within a few minutes at temperatures between room temperature and C) and in the fact that they have good properties adhesion to the materials constituting the box-like housing, for example materials

  plastics of the polyamide or polyester type.

  These resins also have a reduced viscosity (preferably between 1,000 and 30,000 mPa.s at 23 ° C.), which allows them easy penetration into

  the rather narrow interstices of the box-like casing, and good isolating properties

  electrical resistance (for example a volume resistivity greater than 10 ohm.cm).

  Polyurethane-type resins are obtained by mixing a first

  first polyol component with a second isocyanate component.

  The two components may further comprise a series of common additives

  used in the field of plastics production and having

  to achieve the required performance.

  The first component may for example comprise polyols, such as

  polyethers, polyesters and oxhydryl gums, inorganic fillers

  reinforcement, such as calcium carbonates with or without coating,

  Silicates and silicates of Ca, Mg and Al, alumina and hydrated alumina, plastics

  non-reactive fiers, such as phthalates, adipates, sulfonic esters, partially or fully hydrogenated polyphenyls, and naphthenic, paraffinic or aromatic oils, polymerization accelerators, such as tertiary amines, polycyclic amines and organic metal salts such as Sn , Bi, Hg, Zn, Se, Ti and Pt, moisture absorbents, such as zeolites, adhesion promoters, such as silanes, thermal stabilizers and antioxidants, such as

  as substituted phenols or esters of thiodipropionic acids.

  The second component may for example comprise isocyanates of a varied nature (essentially of the TDI and MDI type), both monomers and prepolymers, in addition to plasticizers and non-organic fillers of a type similar to

  to those indicated in connection with the first component.

  The resins are obtained by mixing a first component based on

  epoxy with a second component based on amine or polyaminoamide.

  The first component may for example comprise epoxy resins, produced by reaction of epichlorohydrin with bisphenol A or F, their mixtures or combinations with gums made functional polymers or reactive monomers, and having an equivalent weight of between 170 and 300, reactive epoxy diluents, such as glicydyl ethers, non-reactive plasticizers and

  inorganic loads of a type similar to those indicated in connection with the

sines of the polyurethane type.

  The second component may for example comprise aliphatic amines.

  cycloaliphatic substances and their combinations with epoxides, amides and poly-

  amineamides, accelerators, such as tertiary amines, non-organic

  non-reactive plasticizers of a type similar to those

  with polyurethane resins.

  In a preferred embodiment of the method of the present invention, the aforesaid box-shaped casing made of plastic is subjected to a surface activation treatment, for example by means of exposure to a gaseous plasma or to a corona effect, prior to insertion of the cables and

  sealing with the resin that follows.

  Treatment with ionized gases (plasma) eliminates impurities

  These elements, possibly adhering to the walls of the housing, could compromise good adhesion of the sealants to these walls, thus ensuring the sealing of the connector. Such impurities could in particular be constituted by residues of substances (for example waxes or silicones)

  which are used to make it easier to separate the housing from the mold used

se for its manufacture.

  Another subject of the present invention is a connector that can be obtained

  naked by the method of manufacture described above.

  Other advantages and features of the present invention disclosed

  will be obvious from the following detailed description which is made in re-

  attached drawings, presented only as a non-limitative example, of which:

  FIG. 1 is a perspective view of a connector manufactured in accordance with

  to the process of the invention and Figure 2 illustrates, schematically, the different phases of the

method of the invention.

  In FIG. 1, reference numeral 10 designates an electrical connector, already connected to

  it comprises a box-like housing 12 having a side wall 14 and a bottom grid wall 16 into which are inserted,

  a substantially perpendicular direction, the respective ends 18 of several

  In addition, a tubular appendix 21 protrudes

  on the central portion of the housing 12 to allow its mechanical attachment.

  A two-component, cross-linked resin 22 seals the interstices

  both between the cables 20 and the walls 14, 16 of the box, which is made of

  re plastic, for example of the polyamide or polyester type.

  An example of a method of manufacturing the connector 10 is described

following after.

  The housing 12 (shown schematically in a) in Figure 2 is subject

  in (b) a plasma treatment, in a device indicated schematically

  24, prior to the installation of the cable ends.

  20 and sealing resin 22 within this housing.

  Such a treatment is intended to activate the surface of the housing 1 2 and eliminate

  impurities, possibly adhering to these walls, which could compromise

  put the subsequent adhesion of the resin 22.

  Apparatus 24 that can be used to perform the treatment at

  Plasma is of a conventional type and allows to obtain, after a period of treatment,

  within a few minutes, surface tension values of the material constituting the housing 12 which are greater than 56 dynes / cm and an angle

  contact of the order of 17 or less.

  Such values make it possible to obtain optimum adhesion of the residence.

22 to the walls of the housing 12.

  Once this operation is completed, we insert (in c) the ends of the

  cables 20 in the bottom wall of the housing 12 which is grid-shaped.

  The box-shaped casing 12 is then put in place (in d).

  in an envelope 26 on the bottom of which is placed a layer of wax

  due to low melting point material or high viscosity liquid 28.

  the housing 12 on the layer of melted wax 28 which is then solidified

  (e), so as to close the holes in the grid-like wall of the bottom 14 (end).

gure 1).

  The resin of the polyurethane type 22 is then cast (in f) into the

  2 5 interstices between the walls 14, 16 of the housing 12 and the cables 20, this resi-

  not being prevented from exiting by the layer of wax 28.

  This operation is performed by means of a mixing machine and

  two-component resins which is in itself known and is shown schematically

  30 by the reference 30 (in f).

  The machine 30 preferably has a plurality of outlet ducts 32 which

  allow the resin 22 to flow so as to ensure a distribution of this

  as uniformly as possible inside the case 1 2.

  According to a first example of composition of the resin 22,

  parts by weight of a first component and from 20 to 40, preferably 30,

  by weight of a second component.

  The composition of the first component is as follows: Poly BD 45 HT (hydroxyl endblocked butadiene liquid functional polymer, produced by Atochem) -50 parts (preferably 40 parts) PU thinner (alcohol ether produced by Bayer) 0-10 parts (preferably 5 parts) - Ethylhexanediol (polyol) 0-10 parts (preferably 5 parts)

  - DABCO 33LV (a catalyst consisting of a mixture of triethylenediamine and di-

  propylene glycol, produced by Air Products) 0-1 part (preferably 0.1 part)

  - OMYA BSH (inorganic filler mainly based on calcium carbonate

  cium, produced by OMYA) 30-60 parts (preferably 55.9 parts) SYLOSIV A4 (molecular sieve having a function of absorbing moisture, produced by GRACE) 0-10 parts (preferably 4 parts) IRGANOX 1010 + IRGANOX P5800 (thermal stabilizers and antioxidants, produced by CIBA) 0 - 2 parts (preferably 0.6 parts)

  The second component, on the contrary, consists entirely of a poly-

  isocyanate prepolymer based on diphenylmethane diisocyanate (for example

DESMODUR VL, produced by BAYER).

  According to another example of composition of the resin 22, parts by weight of a first component and 20-40 (preferably 30) parts are mixed.

by weight of a second component.

  The composition of the first component is as follows: - VORANOL CP 4711 (4700 molecular weight triol, produced by DOW) - 20 parts (preferably 18 parts) - VORANOL CP 455 (450 molecular weight triol, produced by DOW) - 15 parts (preferably 12 parts) - ricin oil (natural at maximum acidity 0.5%) -10 parts (preferably 6 parts) - SYLOSIV A4 (molecular sieve - zeolite - produced by GRACE) 0-10 parts (preferably 4 parts) - hydrated alumina SH150 (AI2033H20, produced by PECHINEY) - 60 parts (preferably 50 parts) - PALATINOL N (diisononylphthalate, produced by BASF) 0-10 parts (preferably 9.8 parts) - DESMORAPID PP (accelerator tertiary amine, produced by BAYER) 0-0.5 part (preferably 0.2 part) The second component consists of a prepolymer polyisocyanate based on diphenylmetanediisocyanate (for example SUPRASEC DNR, produced by ICI). This prepolymer also has self-extinguishing characteristics.

  The properties of the resin 22 obtained by mixing the first and second

  The components are as follows: Viscosity at 23 ° C (Brookfield RVT) 10,000-15,000 mPa · s (preferably 12,000 mPa · s) Gel time about 100g at 23 ° C min Volume resistivity 10 ohm.cm Shore hardness A to 23 C-80 is then allowed the resin 22 cast in the housing 12 to crosslink and solidify at room temperature (g) Figure 2 for a period of time

between 1 and 3 minutes.

  The connector 10, now complete and still supported on the wax layer 28 which occupies the bottom of the envelope 26, is then passed (in h) into a tunnel oven 34 maintained at a temperature of between 100 ° C. and 120 ° C. approximately, so as to cause the fusion of the wax 28 and to make free the

connector 10.

  Thus, this connector is ready (in i) to be sent to the place of use.

  tion, while the envelope 26 and the associated wax 28 can be reused in

  a subsequent production cycle of another connector 10.

  It is of course obvious that, the principle of the invention remaining valid, the particular features and the embodiments can vary to a large extent with respect to what has been described and shown in the drawings,

  without thereby departing from the scope of the present invention.

Claims (7)

  A method of sealing an electrical connector (10) comprising the steps of:   - to insert, in a housing (12) box-shaped, the ends respectively   connecting the cables (20) to the walls of the housing (12) by means of a resin (22), said method being characterized by the the resin (22) used is a   two-component and crosslinkable resin.   2. Method according to claim 1, characterized in that the resin (22)   is of the amino-epoxy type and preferably of the polyurethane type.   3. A method according to any one of the preceding claims,   characterized in that the box-shaped housing (12) is made of plastic material and is subjected to superficial activation treatment prior to sealing by means of the resin (22).   4. Method according to claim 3, characterized in that the superficial activation treatment is performed by means of an exposure of the housing (12) to   a gas plasma or a corona effect.   5. Method according to any one of the preceding claims,   characterized in that the box-like housing (12) has a side wall   (14) and a bottom portion (16) and that the ends (18) of the cables   electric cables (20) are inserted into the bottom wall (16) of the housing (12)   in a direction substantially perpendicular to the bottom wall (16).   6. Method according to claim 5, characterized in that, prior   when sealed with the resin (22), the housing (12) is   box in an envelope (26) on the bottom of which is arranged a cou-   melted wax, low melting point material or high viscosity liquid.   vee (28), by causing the bottom wall (14) to rest on the layer (28), which is then solidified, and after sealing, by means of the resin (22), gaps between the ends (18) of the cables (20) and the side wall (14) of the housing (12), the layer (28) is melted, thereby allowing the separate from the housing (12).   7. Electrical connector (10) obtainable by executing a   method according to any one of the preceding claims.