Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-01-26
2001-06-19
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S033000, C528S034000, C528S043000, C528S421000, C528S029000, C549S512000, C549S555000, C549S215000, C556S458000, C556S457000, C556S450000, C556S459000, C525S476000, C525S533000
Reexamination Certificate
active
06248854
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an epoxysiloxane condensate modified by means of an in situ reaction with an organic compound, preferably a di-functional or multi-functional compound.
BACKGROUND OF THE INVENTION
From German Patent document number 43 28 465, a method is known for manufacturing epoxysiloxane condensates in which epoxysiloxanes are obtained by condensation of epoxy-functional alkoxysiloxanes with silanoles. These epoxysiloxane condensates can be used either directly as casting resins or for mixing with epoxy resins for electronics applications. The casting resin systems with epoxy-containing siloxanes are also suitable for the manufacture of temperature-stable and thermomechanically loadable molding materials. The epoxysiloxane condensates have a general structure that can be derived from the epoxyalkoxysilanes used and the silanoles used and chemical analyses. In order further to adapt the epoxysiloxane condensates to the specific areas of use, it is desirable to be able to vary the electronic and steric ratios and also the polarity of the resins within wide limits. By means of the chemical modification of the condensates, custom-tailored casting resins are made available that can be adapted in a particularly flexible fashion to the technical requirements in processing and later operation.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a method for modifying epoxysiloxane condensates as well as modified epoxysiloxane condensates in which the chemical-functional structure of the products can be adjusted within wide limits.
The general recognition of the invention is that in alkoxysilanol condensation the ratio of reactive silanol groups to the alkoxy groups of the epoxy-functional siloxanes can be adjusted in wide limits in such a way that not all alkoxy groups are consumed by silanoles. These alkoxy groups still free after the reaction with the silanoles can be converted in a further condensation step with organic compounds that are as multifunctional as possible. By means of the construction of different organic compounds, the physico-chemical characteristics of the casting resins can be purposively influenced. The possibly contained further functionalities of the organic compounds (also called modifiers) serve as additional points of connection of the obtained siloxane casting resins in the epoxy resin cross-linkages. The epoxysiloxanes can thereby be built into the epoxy resin cross-linkage even more effectively.
The subject matter of the invention is a modified epoxysiloxane condensate that can be obtained by means of the following condensation steps:
a) Condensation of an epoxyalkoxysilane of the general structure 1 with a silanol of the general structure 2
whereby
R
1
stands for an alkyl residue with 1 to 22 C atoms or an aryl residue,
R
2
is a glycidyloxyalkyl residue, epoxyalkyl residue or an epoxycycloalkyl residue, the two residues
R
3
stand for OR
1
or R
2,
independently of one another, or for a further alkyl or aryl residue,
R
4
means alkyl- or aryl-, the residues
R
5
stand for OH or R
4
, independently of one another, and
n is a whole number greater than 1
and
b) condensation of the alkoxy-group-containing epoxysiloxane condensate obtained in this way with a stoichiometric quantity of an organic compound with a linear, branched or cyclical, aromatic if warranted, carbon structure of 1 to 24 C atoms and at least one condensable functional group.
In addition, the subject matter of the present invention is a method for modifying epoxysiloxanes in which, in a first condensation step,
a) an epoxysiloxane 1 is condensed with a silanol 2, whereby 1 and 2 are the compounds indicated above, and after reaction of the silanol 2, in a further condensation step,
b) the alkoxy-group-containing epoxysiloxane condensate so obtained is condensed in situ with an organic compound with a linear, branched, or cyclical, and aromatic if warranted, carbon structure of 1 to 24 C atoms.
Finally, the subject matter of the present invention also includes the application of the inventively modified epoxysiloxane condensate for mixing with standard epoxy resins. The time at which the mixing with the epoxy resin takes place can thereby be selected arbitrarily during, before and after the reaction sequence a) condensation of 1 with 2, then b) condensation of the obtained alkoxy-group-containing epoxysiloxane condensate with an organic compound, di-functional or multifunctional if warranted.
Other objects and advantages of the present invention will become apparent from reading the following detailed description and appended claims, and upon reference to the accompanying drawings.
REFERENCES:
patent: 4851481 (1989-07-01), Kuriyama et al.
patent: 5280098 (1994-01-01), Witucki et al.
patent: 0 468 239 A2 (1990-07-01), None
patent: 0 641 826 A1 (1993-08-01), None
patent: WO 95/06050 (1993-08-01), None
Hohn Klaus
Wipfelder Ernst
Dawson Robert
Peng Kuo-Liang
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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