Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1993-06-14
1995-05-02
Reddick, Judy M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524476, 524502, 524531, 524548, 524556, 524563, 524564, 524533, 525274, 5253278, 5253302, 525370, C08L 4302
Patent
active
054120225
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a lyo gel, to its production and to its use for sealing, more particularly devices involving the use of electrical current. The lyo gel consists of at least two components, namely a network of a copolymer containing at least one comonomer bearing functional groups of carboxylic acid and carboxylic anhydride on the one hand and polyvalent metals on the other hand as gelling agent and an organic liquid as dispersant.
2. Discussion of Related Art
One such lyo gel is described in DE-OS 26 49 544, according to which a gel is formed from an alkyl acrylate copolymer of alkyl acrylate, .alpha.,.beta.-unsaturated carboxylic anhydrides, more particularly 0.2 to about 20% by weight maleic anhydride, and ethylenically unsaturated monomers, which is dissolved in an organic solvent, and from a metal alkoxide on storage at room temperature (see page 10, lines 4 to 8). The organic solvents are readily volatile substances so that the polymer solution rapidly dries (see page 12, paragraph 2). Since gelation is undesirable, at least 20% by weight of a lower aliphatic alcohol is added and the metal alkoxides are chelated (see page 5, last paragraph to page 6, line 3 and page 10 from line 12 to page 11, paragraph 3). Octylene glycol, triethanolamine, 2,4pentanedione or lactic acid are specifically mentioned, acetyl acetonates being preferred. The copolymer solution thus stabilized is used as an adhesive. After removal of the solvent, including the alcohol, the copolymer crosslinks and gives bonds of high cohesive strength (see page 13, paragraph 2).
A similar copolymer is described by Milka and Czech in "Adhasion" (1985), pages 29 to 32. A copolymer of 2-ethylhexyl acrylate, n-butyl acrylate and hydroxyethyl acrylate and also acrylic acid is dissolved in ethyl acetate, methyl ethyl ketone and acetone and crosslinked with titanic acid esters and metal acetyl acetonates (see page 29, middle column). Where organoyl titanate is used, a gel is formed, even in the presence of alcohols (see page 31, middle column). However, this is undesirable. Instead, the polymer solutions are used as contact adhesives because the acrylate copolymers crosslink spontaneously after evaporation of the alcohol and the other solvents (see page 29, left-hand column).
Other pressure-sensitive adhesive mixtures of the type in question are described in DE-OSS 24 16 991 and 23 37 558.
In all these cases, the object is to produce pressure-sensitive adhesives. The formation of gels is undesirable. The gels nevertheless obtained are attended, for example, by the disadvantage that, for a solids content of 10 to 60%, the rest of the solvent has to be removed which involves a contraction in volume (page 21 of DE-OS 24 16 991). A reduction in volume during drying also occurs in the case of DE-OS 23 37 558. The gels obtained are not fluid at room temperature and do not have an adequate sealing effect. There is no reference to their use as sealants.
The function of sealants is to fill gaps, joints and spaces between bodies in a volume-bridging, gas-tight and liquid-tight manner by plugging. Thus, spaces in cables and their connecting elements, such as free connectors, raceways, joint boxes, etc., are frequently filled to seal them against environmental influences, such as water, dust, air, oil, etc. and to provide mechanical and electrical protection.
Sealing systems based on the following macro-molecular substances are used for this purpose: molding compounds, etc., and
The known systems have the following disadvantages: application temperature and the in-use temperature. This gives rise to stresses which can even lead to cracks and leaks, particularly in the case of systems A), B) and D). because, outside this more or less narrow range, they lose mechanical strength, break, flow out or decompose. This applies in particular to systems A), B) and D). materials. This generally applies to systems A), B), C) and D).
4.) The sealants are not sufficiently plastic, for example when further con
REFERENCES:
patent: 4012567 (1977-03-01), Loveless
patent: 4062817 (1977-12-01), Westerman
patent: 4130213 (1978-12-01), Wszolek
patent: 4200561 (1980-04-01), Chang
patent: 4929690 (1990-05-01), Goertz et al.
patent: 4985506 (1991-01-01), Blum et al.
patent: 5149745 (1992-09-01), Owens et al.
patent: 5218011 (1993-06-01), Freeman
patent: 5256705 (1993-10-01), Freeman
Milka and Czech, "Adhasion" (1985), pp. 29-32.
"Adhesives Age" (1989), pp. 24-29.
Andres Johannes
Heucher Reimar
Wichelhaus Juergen
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Reddick Judy M.
Szoke Ernest G.
Wood John Daniel
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