Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Patent
1996-11-05
1998-04-14
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
528901, 524588, 524837, C08G 7726
Patent
active
057392480
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a kit for the production of rapidly hardening, aminosilane cross-linking silicone masses consisting of at least bi-functionally terminated diorganopolysiloxanes, aminosilane cross-linking agents, as well as possibly filling materials, suitable additives, pigments, colouring materials, oxidation-, heat- and light-protecting pigments, as well as solvents and plasticisers, as well as the use as adhesives or moulding materials.
Such organopolysiloxane mixtures, also known as cold-vulcanising, single component silicone rubbers, usually cross-link at room temperature with the take-up of water from the surrounding atmosphere to give rubber-elastic polymers. As chain lengtheners and cross-linkers, there are used bi- and higher functional aminosilane compounds which, by reaction with the polysiloxsne or by hydrolysis, split off amines and so initiate the formation of a macromolecular meshwork. After hardening has taken place, such masses are characterised by a good inherent adhesion on the most varied work material surfaces and by a generally high stability against the action of temperature, light, moisture, as well as chemicals.
The hardening of such single-component polysiloxane mixtures cross-linking at room temperature with the take-up of moisture takes place comparatively slowly since the water necessary for the reaction must diffuse into the interior of the mass in gaseous form from the surrounding atmosphere. Therefore, the speed of the hardening decreases with progressing reaction in the interior of the mass. In the case of low atmospheric humidity or in the case of an unfavourable ratio of surface to volume of the silicone mass, the reaction can become very slow or, as in moisture-tight closed spaces, can also come to a stop.
The per se diverse possibilities of use of such atmospheric moisture-hardening silicones as sealing or adhesive material are especially limited in the case of use for industrial purposes because of the slow hardening. Admittedly, two-component silicone rubber systems hardening rapidly at room temperature or hardening first at a higher temperature are known but the use thereof fails frequently because of the deficient inherent adhesion or also of the comparatively low temperature stability of these products. If, however, one uses silicones hardening only slowly under the influence of atmospheric moisture, in the case of short cycle times desired for economic reasons, large intermediate storages are necessary for the sealed-off or stuck parts in order to ensure the hardening. These intermediate storages must, in addition, possibly be climatised or moistened. Under certain circumstances, in this way, very large numbers of pieces are already produced before a testing for freedon from fault and function of the goods produced is first possible. Large-surface adhesions between diffusion-tight surfaces can, in practice, be carried out with atmospheric moisture-hardening silicones, such as the production of moulded bodies in closed moulds.
If one adds water in liquid form to the known aminosilane-containing and atmospheric moisture-hardening masses, in comparison with the cross-linking with atmospheric moisture a certain acceleration of the hardening is achieved. However, this form of the cross-linking does not lead to end products with material properties such as are obtained in the case of purely atmospheric moisture cross-linking. On the contrary, masses result which, in the long term, remain substantially softer, display poor inherent adhesion and are still swollen for a long time with the amine resulting as cross-linking cleavage product. The amine smell, generally found to be extremely unpleasant, is also maintained correspondingly long.
Similar results, thus only small hardening acceleration combined with comparatively poorer material properties and with long-lasting amine smell, are obtained when water is added in the form of salts containing water of crystallisation or also knowingly surface-moistened materials.
Thus, the task forming the basis of the in
REFERENCES:
patent: 4462828 (1984-07-01), Otsuki
patent: 4592959 (1986-06-01), Wong
patent: 4593085 (1986-06-01), Lucas
Heidelberger Baustofftechnik GmbH
Marquis Melvyn I.
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