Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Patent
1993-04-16
1995-01-17
Kight, III, John
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
528 745, 528905, C08G 1858
Patent
active
053826477
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a polyurethane-based friable sealing compound produced from a polyol component and an isocyanate component.
In many fields of industry, a housing, a tube or similar articles have to be sealed at their open end(s) so that moisture or water is unable to penetrate. This applies in particular to cables for the transmission of information, for example in the communications field and in various parts of the electrical industry.
2. Discussion of Related Art
Communications cables consist of a plurality of electrically conductive wires which are bunched together, several such bunches being, accommodated in an outer protective sheath. To join two such cables or even to join cables of different construction to one another, these bunches of wires have tn be fanned out and joined to the wires of the other cable. The individual wires thus joined have to be insulated from one another, so that, in some cases, a much more bulky structure is formed. Since the insulation of the individual wires was opened, this structure has to be protected against the penetration of moisture or water. This is done by so-called cable fittings in the form of connectors consisting of a joint box and a plastics material accommodated therein, this plastics material being known as a friable sealing compound because it is required to show high notch sensitivity. Friable sealing compounds can be removed easily by hand without any need for special tools. They must have a high volume resistance, for example where they are used in cable fittings, and in addition their so-called pot life during processing should be long but, if necessary, should be able to be shortened by addition of catalysts.
In view of the efforts being made to replace petrochemical products by renewable raw materials, it would be desirable if friable sealing compounds could be provided on the same basis. Finally, a friable sealing compound should as far as possible be a homogeneous product, i.e. a uniform product with no additives.
DESCRIPTION OF THE INVENTION
The problem of providing such friable sealing compounds pounds has been solved by the friable sealing compound according to claim 1. Further advantageous embodiment can be found in the subsidiary claims.
Accordingly, the friable sealing compounds according to the invention consist of only one technical product of which the polyol component is obtained from renewable raw materials. They have high stability in storage and a high electrical resistance coupled with excellent friability. In addition, they are free both from solvents and from plasticizers so that there is no separation or migration of such additives with the disadvantages normally involved. In addition, the friable sealing compounds according to the invention are, surprisingly, completely transparent which enables electrical connections etc. embedded in the friable sealing compound according to the invention to be visually and hence non-destructively inspected so that faults in need of repair can be located much more easily and unnecessary work and wastage of material can be avoided.
The polyol component according to the invention is selected from modified triglycerides, for example of the type described in DE-A1 32 46 612, which can be obtained by partial ring opening of epoxidized triglycerides of a fatty acid mixture at least partly containing olefinically unsaturated fatty acids with monohydric or polyhydric alcohols.
In principle, the isocyanate component according to the invention may be selected from any of the usual poly-functional aromatic and aliphatic isocyanates, such as for example even oligomeric or polymeric isocyanate compounds, of which HDI trimer (tris-6-isocyanatohexyl isocyanurate), polyisocyanate (4,4-diphenylmethane diisocyanate (MDI)) and HDI biuret (1,3,5-tri-(6-isocyanatohexyl)-biuret are mentioned as examples. Non-toxic compounds which do not require identification are particularly preferred.
The OH:NCO equivalent ratio is 1:0.1 to 1:1.15 and, more particul
REFERENCES:
patent: 4551517 (1985-11-01), Herold et al.
patent: 4603188 (1986-07-01), Kusakawa et al.
patent: 4826944 (1989-05-01), Hoefer et al.
patent: 4886893 (1989-12-01), Meffert et al.
Daute Peter
Gruetzmacher Roland
Hoefer Rainer
Stoll Gerhard
Grandmaison Real J.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Johnson R.
Kight III John
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