Stock material or miscellaneous articles – Sheets or webs edge spliced or joined – Sheets or webs coplanar
Patent
1997-01-09
1999-09-14
Gulakowski, Randy
Stock material or miscellaneous articles
Sheets or webs edge spliced or joined
Sheets or webs coplanar
4283044, 4283173, 4283177, 428347, 428349, 428355R, 428355EP, 428413, 4284744, 427516, 525423, 525432, 525425, B32B 300
Patent
active
059520710
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a two-part curable adhesive system, and especially to such systems which may be very suitable for blocking electrical cables and harnesses to prevent penetration of fluids between the wires of the cable or harness.
INTRODUCTION TO THE INVENTION
Known blocking adhesives tend to suffer from problems such as inability to penetrate adequately into the cable wire bundle, or excessive flow along the wire bundle, or inability to maintain adequate cable blocking action when the blocked cable is tested after exposure to temperatures above 110.degree. C., for example 3000 hours at 125.degree. C. and 240 hours at 150.degree. C.
SUMMARY OF THE INVENTION
The adhesive system of the present invention provides room-temperature stability and defines for the first time the "window" of melt flow characteristics and controlled speed and level of reaction in the molten state, which combine to alleviate the problems of the previously known blocking adhesives and tend to produce reliable blocking capable of achieving the aforementioned temperature performance, as hereinafter described.
The invention accordingly provides a two-part curable adhesive system comprising Part A material and Part B material, both of which Parts (A and B) comprise polymeric material and are substantially solid or substantially non-flowable at temperatures up to 60.degree. C. and are substantially unreactive in contact with each other at temperatures up to 40.degree. C.,
and which Parts (A and B) are capable of flowing and reacting together when heated in contact with each other to temperatures above 80.degree. C., preferably within the range from 80 to 150.degree. C.,
the materials of Part A and Part B being selected and proportioned so that each of the Parts A and B individually has a Brookfield viscosity less than 200 Pa.s at 80.degree. C., and preferably less than 50 Pa.s at 100.degree. C., and preferably less than 20 Pa.s at 120.degree. C.,
and preferably being selected and proportioned so that the viscosity of either Part is not more than 2 times (preferably not more than 1.5 times, more preferably not more than 1.33) times that of the other part at the same temperature within the range from 80 to 150.degree. C.
wherein material (preferably polymeric material) of at least a first type included in Part A carries reactive groups of at least a first kind, and wherein Part B is substantially free from reactive groups of the kind or kinds contained in Part A, and Part B includes material (preferably polymeric material) of the said first type and/or of a second type (preferably substantially completely compatible with the said first type), and wherein material (preferably polymeric or oligomeric material) included in Part B carries reactive groups of at least a second kind capable of reacting with the said reactive groups contained in Part A when the Parts A and B are heated together as aforesaid,
and wherein the proportion of the said reactive groups in Part A and/ or in Part B respectively 60.times.10.sup.-5 moles, more preferably at least 90.times.10.sup.-5 moles), of the said reactive groups per gram of total material present in the relevant Part, 150.times.10.sup.-5 moles), of the said reactive groups per gram of total material present in the relevant Part,
and wherein the reactivity and proportions of the said reactive groups in Part A and Part B are selected so that, when the Parts are heated to flow and react together, the Brookfield viscosity of the resulting reacting mixture of Part A and Part B
(a) remains below 300 Pa.s C., 100.degree. C., and 150.degree. C.
(b) rises to at least 1000 Pa.s C.,
DETAILED DESCRIPTION OF THE INVENTION
It is comparatively easy to select materials for making Part A and Part B of the system which are substantially solid or at least substantially non-flowable, at temperatures up to 60.degree. C. The materials are also selected so that Part A and Part B are substantially unreactive when placed in contact with each other at temperatures up to 40.degree. C.
The
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De Blick Gerry
Kennan Aine
Miles Graham
Overbergh Noel
Rijsdijk Henk
Burkard Herbert G.
Gerstner Marguerite E.
Gulakowski Randy
N.V. Raychem S.A.
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