Earth boring – well treating – and oil field chemistry – Well treating – Contains organic component
Reexamination Certificate
2001-11-14
2003-11-04
Tucker, Philip (Department: 1712)
Earth boring, well treating, and oil field chemistry
Well treating
Contains organic component
C507S234000, C166S292000, C166S295000
Reexamination Certificate
active
06642184
ABSTRACT:
The present invention relates to use of inhibitor compounds, in particular inhibitor compounds suitable for inhibiting curing of an organosilicon composition by a hydrosilylation reaction. More particularly, the present invention relates to the use of inhibitor compounds for inhibiting curing of an organosilicon composition by a hydrosilylation reaction under extreme environmental conditions.
Many organosilicon compositions cure by a hydrosilylation reactions, in which a transition metal containing catalyst, for example a platinum group containing compound or complex, is used to catalyse a hydrosilylation reaction, typically between olefinic groups of a siloxane polymer containing aliphatic unsaturation and hydrogen atoms of a cross-linker compound containing silicon-bonded hydrogen atoms. Inhibitor compounds are used to inhibit the transition metal catalyst from catalysing the hydrosilylation reaction and hence inhibit curing of the organosilicon composition, for example to reduce cure rate and/or extend pot life of the organosilicon composition. Such inhibitors are well known in the art and are commercially available. Examples of these inhibitors include unsaturated organic compounds such as ethylenically or aromatically unsaturated amides (eg see U.S. Pat. No. 4,337,332), acetylenic compounds (U.S. Pat. Nos. 3,445,420 and 4,347,346), ethylenically unsaturated isocyanates (U.S. Pat. No. 3,882,083), olefinic siloxanes (U.S. Pat. No. 3,989,667), unsaturated hydrocarbon diesters (U.S. Pat. Nos. 4,256,870, 4,476,166 and 4,562,096), conjugated ene-ynes (U.S. Pat. Nos. 4,465,818 and 4,472,563, hydroperoxides (U.S. Pat. No. 4,061,609), ketones (U.S. Pat. No. 3,418,731), sulphoxides, amines, phosphines, phosphates, nitriles (U.S. Pat. No. 3,344,111), diaziridines (U.S. Pat. No. 4,043,977), acetylinic alcohols (U.S. Pat. No. 3,445,420), unsaturated carboxylic esters (U.S. Pat. No. 4,256,870), maleates and fumarates (U.S. Pat. Nos. 4,562,096 and 4,774,111). Organosilicon compositions which contain an inhibitor may be cured by raising the temperature of the composition to the boiling point of the inhibitor, thus evaporating the inhibitor and allowing the hydrosilylation catalyst to catalyse the hydrosilylation reaction and hence cure the organosilicon composition.
Silicones have characteristics which make them particularly useful in applications where extreme environmental conditions exist, for example their high resistance to heat and chemical attack. For example, WO 99/43923 discloses a method for carrying out well construction, repair and/or abandonment operations which comprises using an addition-curing silicone formulation. However, a problem with the use of commercially available silicones in extreme environmental conditions such as these is that the conditions may cause the organosilicon composition to cure en route to the desired location, for example in an oil well, which causes blockages within the pumps, pipework and other equipment used to get the organosilicon composition to the desired location.
The present inventors have found that conventional inhibitors suitable for inhibiting curing of organosilicon compositions by a hydrosilylation reaction can be used to reduce the cure rate of an organosilicon composition in conditions of elevated temperature and pressure sufficiently to enable arrival of the organosilicon composition at a desired location substantially uncured.
According to the present invention there is provided use of an inhibitor compound in an organosilicon composition for inhibiting curing of the organosilicon composition by a hydrosilylation reaction at a temperature of from 40° C. to 100° C., or 100° C. and above, and a pressure of 1×10
6
N/m
2
to 5×10
6
N/m
2
, or 5×10
6
N/m
2
and above.
The cure time for a particular organosilicon composition used in the present invention will depend upon the particular composition in question and the severity of the cure conditions. However, typical cure times may be the order of 4 to 12 hours. By way of comparison, the same organosilicon composition without a cure inhibitor will cure in minutes.
In a preferred application, the organosilicon composition cures to form a silicone gel or elastomeric seal or plug within an oil or gas well.
Any inhibitor compound may be used in the organosilicon composition which is effective at inhibiting curing of the organosilicon composition by a hydrosilylation reaction. Such inhibitors are commercially available and are referred to hereinabove. Preferred inhibitor compounds include aromatic alcohols, alkynyl alcohols and their derivatives, methylvinylcyclosiloxanes, and fumarates and maleates. Examples of suitable aromatic alcohols include benzyl alcohol, 1-phenyl-1-butanol, and 4-phenyl-1-butanol. Examples of suitable alkynyl alcohols and their derivatives include, 1-ethynyl-1-cyclopentanoly, 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,7-dimethyl-3-5-octadiyne-2, 7-diol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 2,4,7,9-tetramethyl-5-decyne-4, 7-diol, 1,4-Bis(1′hydroxycyclohexyl)-1,3-butadiyne, 1-(1-butynyl)cyclopentanol, 2,5-dimethyl-5-hexen-3-yn-2-ol, 5-dimethylamino-2-methyl-3-pentyn-2-ol, 3,4,4-trimethyl-1-pentyn-3-ol, 3-isobutyl-5-methyl-1-hexyn-3-ol, 2,5,8-trimethyl-1-nonen-3-yn-5-ol, 1-(1-propyny) cyclohexanol, 3-4dimethyl-1-pentyn-3,4-diol, 2,3,6,7-tetramethyl-4-octyn-3,6-diol, and 4-ethyl-1-octyn-3-ol; examples of methylvinyl cyclosiloxanes include tetramethylvinylcyclotetrasiloxane and pentamethylvinylcyclopentasiloxane, and examples of fumarates and maleates include diethyl fumarate and diethyl maleate respectively. Particular preferred inhibitors are 1-ethynyl-1-cyclopentanol and 1-ethynyl-1-cyclohexanol.
The inhibitor is preferable present in the organosilicon composition in an amount of from 1 to 10 wt. %, more preferable from 2 to 5 wt. %.
The organosilicon composition may comprise a siloxane polymer having aliphatic unsaturation, an organosilicon cross-linker having Si—H functionality and a catalyst. Preferably the siloxane polymer is a linear polyorganosiloxane having the general structure (I)
wherein R is a monovalent hydrocarbon group having up to 18 carbon atoms, R′ is a monovalent hydrocarbon group having up to 6 carbon atoms or a hydrogen atom, and x is an integer, for example having a value of from 10 to 1500. It is particularly preferred that R denotes an alkyl or aryl group having from 1 to 8 carbon atoms, eg methyl, ethyl, propyl, isobutyl, hexyl, phenyl or octyl. More preferably at least 50% of all R groups are methyl groups, most preferably substantially all R groups are methyl groups. R′ is preferably selected from an aliphatically unsaturated hydrocarbon group or a hydrogen atom. More preferably R′ denotes an alkenyl group having up to 6 carbon atoms, more preferably vinyl, allyl or hexenyl suitable for hydrosilylation reactions.
The organosilicon cross-linker is preferably selected from silanes, low molecular weight organosilicon resins and short chain organosiloxane polymers. The cross-linker compound has silicon-bonded substituents which are capable of reacting with the silicon-bonded aliphatically unsaturated hydrocarbon groups or hydrogen atoms R′ of the siloxane polymer described above. Where the group R′ in the polymer is an alkenyl group, it is preferred that the reactive substituents on the cross-linking organosilicon compound are hydrogen atoms, allowing a hydrosilylation reaction between the cross-linking organosilicon compound and the polyorganosiloxane according to the general reaction scheme (I), wherein R″ is a divalent hydrocarbon group and y is 0 or 1.
≡Si—R″
y
CH═CH
2
+H—Si≡→≡Si—R″
y
CH
2
—CH
2
—Si≡ (I)
Suitable organosilicon cross-linking compounds include organosilicon resins consisting mainly of tetrafunctional siloxane units of the formula SiO
4/2
and monofunctional units R
V
R
o
w
SiO
1/2
, where in R is as defined above, R
o
denotes a silicon-bonded substit
Dow Corning S.A.
McKellar Robert L.
McKellar Stevens
Tucker Philip
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