Dow Corning Corporation

Sherwood Spells

Chi-long Lee

Loren D Lower

Richard Alan Palmer

Beth I Gutek

Ronald W Wieck

James R Warren

A process of making a polydiorganosiloxane-silica foundation mixture from a free-flowing, powdered, surface-modified, reinforcing silica-polydiorganosiloxane concentrate used to make, for example, RTV silicone sealant compositions which have non-sag properties. The foundation mixtures are made by combining, mixing, and heating a reinforcing silica filler and a diol surface modifying agent to a temperature of 20.degree. C. to &lt;180.degree. C. using 0.05 to 0.5 parts by weight of the diol per one part by weight of the silica. Polydiorganosiloxane is added gradually to the resulting fluidized filler over a time period of less than 10 minutes to obtain the free flowing powdered reinforcing silica-polydiorganosiloxane concentrate. The foundation mixture is obtained by massing the concentrate and adding more polydiorganosiloxane to obtain a mixture which has from 5 to 20 weight percent silica filler. The foundation mixtures have a plateau stress of &gt;700 dynes/cm.sup.2 and a shear-thinned viscosity of no more than 1,000 Pa.s at a shear stress of 50,000 dynes/cm.sup.2. RTV silicone sealant compositions can be obtained in 10 to 15 minutes from the start of making the surface modified silica filler to the complete sealant composition.

Method of making a foundation polydiorganosiloxane-silica mixture, the

A process of making a pumpable, stable, polydiorganosiloxane-silica foundation mixture by mixing and heating a polydiorganosiloxane, a reinforcing silica filler, and a diol surface modifying agent at &gt;50.degree. C. to &lt;180.degree. C. using 0.05 to 0.5 parts by weight of the diol per one part by weight of the silica. The foundation mixture can be used to make RTV silicone sealant compositions which are non-sag.

Method of making a pumpable, stable polydiorganosiloxane-silica

A two part sealant cures rapidly in deep sections when the two parts are mixed together. A first part comprises a hydroxyl endblocked polydiorganosiloxane, non-reinforcing, non-acidic filler, diacetamidosilane chain extender of the general formula ##STR1## and aminoxysilicone compound having from 1 to 100 silicone atoms per molecule and from 3 to 10 aminoxy groups per molecule. A second part comprises a hydroxyl endblocked polydiorganosiloxane, non-reinforcing, non-acidic filler, and hydroxyl endblocked polydiorganosiloxane having a degree of substitution of from about 1 to 50. When mixed together, the two parts cure rapidly in deep sections.

Two-part, ultralow modulus silicone sealant

A silicone sealant composition which bonds to dolomite containing concrete after exposure to moisture is obtained by adding a silicone fluid having greater than 2 mole percent epoxy functionality to a sealant of the type containing a hydroxyl endblocked polydiorganosiloxane, acetamidosilane chain extender, and crosslinking agent selected from the group consisting of triacetamidosilane and aminoxysilicon compound.

Concrete joint sealant having improved adhesion

This disclosure relates to an applicator for placing a sealant into a groove, and comprises a member having a lower side, the lower side being adapted to extend into the groove. The lower side has an arcuate shape and a sealant passage extends through the member and includes an outlet opening in the lower side. The arcuate lower side is adapted to extend partially into said groove and engage the upper corners of the groove during use. The applicator further includes a limiter attached to the member, the limiter extending laterally of the lower side and over the upper corners of the groove.

Sealant applicator

A simplified method of manufacturing a silicone elastomeric foam comprises mechanically generating a stable froth of an aqueous emulsion, while adding surfactant and thickener, then exposing the stable froth to microwave energy to remove the water. The emulsion consists essentially of anionically stabilized hydroxyl endblocked polydiorganosiloxane, colloidal silica, an organic tin compound, and water, the emulsion having a pH in the range of 9 to 11.5 inclusive. The dried froth is an elastomeric, cellular structure possessing typical silicone elastomer heat stability and long-term aging stability.

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Midland, MI, United States of America

Sherwood Spells