1. Field of the Invention
The present invention relates to a room temperature curing organopolysiloxane composition, and in particular to a dealcoholation type room temperature curable trifluoropropylmethylpolysiloxane composition (hereinafter referred to as an RTV fluorosilicone composition) excellent in storage stability and its cured product.
2. Description of the Prior Art
RTV fluorosilicone compositions are excellent in properties, for example, heat resistance, solvent resistance, and acid/base resistance. However, these compositions have a problem that the reactivity of the hydroxyl groups at the terminals of trifluoropropylmethylpolysiloxanes contained as a base polymer is lower than that of the hydroxyl groups at the terminals of dimethylpolysiloxane. Further, there is a problem that the siloxane bond may break under basic conditions. Consequently, these RTV fluorosilicone compositions are available as products only in the form of acidic acetic acid-elimination type RTV fluorosilicone compositions wherein the curing agent is high in reactivity. As a result, the compositions have a defect that they have an irritating order of acetic acid and are strongly corrosive, and therefore the application thereof in electric and electronic industry is restricted.
Further, alcohol removal type RTV silicone compositions have defects that the curing speed is slow and the internal curability and the storage stability are poor and they have a problem that if they are kept for a long period of time even under water-free conditions, they do not cure when used.
On the other hand, an alcohol removal type RTV silicone composition good in storage stability is disclosed in Japanese Pre-examination Patent Publication (kokai) No. 47868/1991. This composition uses, as a so-called alcohol scavenger, an organosilicon compound having a group represented by the following general formula (2): ##STR2## wherein R represents a hydrogen atom, a methyl group, or an ethyl group, R' represents a monovalent hydrocarbon group, and p is an integer of 1 to 3.
However, since the alcohol scavenger disclosed in the above prior art needs to use a basic organosilicon compound as a catalyst, this scavenger cannot be applied to RTV fluorosilicone compositions. That is, this is because the basic organosilicon compound used as a catalyst causes the polysiloxane chain to crack, leading to failure in curing.
USPTO Backgrounds
USPTO Backgrounds