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...
Reexamination Certificate
1999-08-27
2001-10-02
Moore, Margaret G. (Department: 1712)
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...
C524S588000, C524S862000, C524S773000, C528S015000, C528S031000
Reexamination Certificate
active
06297305
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a curable silicone composition, and more specifically a curable silicone composition which can form a cured product with superior matte properties as a result of being cured by a hydrosilylation reaction and a condensation reaction.
BACKGROUND OF THE INVENTION
Curable silicone compositions which are cured by a hydrosilylation reaction and a condensation reaction can be cured by heating or by means of moisture in the air. Accordingly, such compositions are suitable for use as fillers or adhesive agents such as sealing agents, etc., used in electrical and electronic devices, etc.
However, in the case of such curable silicone compositions, the cured product obtained by curing has surface luster; as a result, in cases where this cured product is used as a filler or adhesive agent for the waterproofing of an LED (light-emitting diode) display device, etc., the cured product reflects light from the LEDs and light from the outside, so that the visual recognition characteristics are poor.
Accordingly, attempts have been made to deluster the cured product obtained in such cases by mixing an inorganic filler with the curable silicone composition; however, it has not been possible to endow such compositions with sufficient matte properties. Furthermore, large quantities of filler must be used in order to endow such compositions with matte properties; however, if such large quantities of filler are used, the fluidity of the curable silicone composition that is obtained drops, so that the handling and working characteristics of the composition deteriorate.
The object of the present invention is to provide a curable silicone composition which can form a cured product with superior matte properties as a result of being cured by a hydrosilylation reaction and a condensation reaction.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a curable silicone composition which is cured by a hydrosilylation reaction and a condensation reaction, and which is characterized by the fact that the composition contains an air-oxidation-curable unsaturated compound.
This unsaturated compound is a component which is used to endow the cured product obtained by curing the present composition with sufficient matte properties. Such unsaturated compounds are cured by the oxidation of the unsaturated bonds in the molecule by oxygen contained in the air; typical examples of such unsaturated compounds are aliphatic compounds which have at least two unsaturated bonds per molecule. Examples of such compounds include unsaturated higher fatty acids such as linolenic acid and linolic acid, etc.; fats and oils consisting of esters of unsaturated higher fatty acids and glycerol such as tung oil, linseed oil and soybean oil, etc.; esters of unsaturated higher fatty acids and alcohols such as methyl linolenate and methyl linolate, etc.; unsaturated hydrocarbon compounds such as butadiene, pentadiene and hexadiene, etc.; and polymers of such compounds. In particular, linolenic acid, alkyl linolenates, tung oil, linseed oil, 1,3-hexadiene and polybutadienes are especially desirable.
In the present invention, it is desirable that the content of the abovementioned air-oxidation-curable unsaturated compound be in the range of 0.01 to 50 parts by weight per 100 parts by weight of the silicone component in the present composition; a content in the range of 0.1 to 20 parts by weight is even more desirable, and a content in the range of 0.1 to 10 parts by weight is especially desirable. Note that if the content of this unsaturated compound is less than the lower limit of the abovementioned range, there tends to be an insufficient endowment of the resulting cured silicone product with matte properties. On the other hand, if the content exceeds the upper limit of the abovementioned range, the mechanical characteristics of the resulting cured silicone product tend to deteriorate.
It is desirable that such a curable silicone composition which is cured by a hydrosilylation reaction and a condensation reaction be a composition consisting of at least (A) a mixture of (a) an organopolysiloxane which contains at least two alkoxy groups bonded to silicon atoms in each molecule, and which does not contain any alkenyl groups bonded to silicon atoms, and (b) an organopolysiloxane which contains at least two alkenyl groups bonded to silicon atoms in each molecule, and which does not contain any alkoxy groups bonded to silicon atoms, or alternatively to the combination of (a) and (b), (c) an organopolysiloxane which respectively contains at least two alkoxy groups bonded to silicon atoms and two alkenyl groups bonded to silicon atoms in each molecule,
(B) an organopolysiloxane which contains at least two hydrogen atoms bonded to silicon atoms in each molecule,
(C) a condensation reaction catalyst,
(D) a platinum type catalyst, and
(E) an air-oxidation-curable unsaturated compound.
Component (A) is a mixture of (a) an organopolysiloxane which contains at least two alkoxy groups bonded to silicon atoms in each molecule, and which does not contain any alkenyl groups bonded to silicon atoms, and (b) an organopolysiloxane which contains at least two alkenyl groups bonded to silicon atoms in each molecule, and which does not contain any alkoxy groups bonded to silicon atoms, or (c) an organopolysiloxane which respectively contains at least two alkoxy groups bonded to silicon atoms and two alkenyl groups bonded to silicon atoms in each molecule. Component (a) should have at least two alkoxy groups bonded to silicon atoms in each molecule; if the number of alkoxy groups bonded to silicon atoms is less than two groups per molecule, it is difficult to achieve sufficient curing of the resulting composition by means of a condensation reaction.
The molecular structure of component (a) may be linear, linear with partial branching, or branched. In particular, a linear structure is especially desirable. Examples of alkoxy groups which may constitute the alkoxy groups bonded to silicon atoms in component (a) include methoxy groups, ethoxy groups, propoxy groups, butoxy groups, methoxymethoxy groups and methoxyethoxy groups. In particular, methoxy groups are especially desirable. The bonding positions of these alkoxy groups may be on the terminals of the molecular chains, or on side chains of the molecular chains; bonding on the terminals of the molecular chains is especially desirable, since the reactivity is good in the case of such bonding positions. These alkoxy groups may be directly bonded to silicon atoms of the principal chains, or may be bonded to silicon atoms which are in turn bonded to silicon atoms of the principal chains via alkylene groups. Furthermore, examples of groups other than alkoxy groups which may be bonded to silicon atoms in component (a) include alkyl groups such as methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups and octadecyl groups, etc.; cycloalkyl groups such as cyclopentyl groups and cyclohexyl groups, etc.; aryl groups such as phenyl groups, tolyl groups, xylyl groups and naphthyl groups, etc.; aralkyl groups such as benzyl groups, phenethyl groups and phenylpropyl groups, etc.; and halogenated alkyl groups such as 3-chloropropyl groups and 3,3,3-trifluoropropyl groups, etc. In particular, methyl groups and phenyl groups are especially desirable. Furthermore, it is desirable that the viscosity of component (a) be in the range of 20 to 200,000 mPa·s at 25° C., and a viscosity in the range of 100 to 100,000 mPa·s is especially desirable. Note that if the viscosity at 25° C. is less than the lower limit of the above-mentioned range, physical properties of the resulting cured product such as softness and elongation, etc., tend to deteriorate; on the other hand, if the viscosity exceeds the upper limit of the above-mentioned range, the handling and working characteristics of the resulting composition tend to deteriorate.
Examples of organopolysiloxanes which can be used
Nakata Toshiki
Onishi Masayuki
Dow Corning Toray Silicone Company, Ltd.
Milco Larry A.
Moore Margaret G.
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