Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2000-06-07
2001-11-06
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
C149S019200, C044S361000
Reexamination Certificate
active
06313334
ABSTRACT:
The invention relates to ferrocene dicarboxylic acid diesters having the general formula
to processes for preparing the same, their use, solid composite propellants containing the ferrocene. dicarboxylic acid diesters in accordance with the invention, and to processes for preparing the same.
Ferrocenyleaters are known in principle from the prior art, for example 2(2-n-butoxyethoxy)ethyl ferrocene from U.S. Pat. No. 3,558,680, which can be prepared from ferrocene carboxylic acid and 2(2-n-butoxyethoxy) ethanol.
Ferrocene derivatives are used in the widest variety of fields, among others also as combustion moderators for solid propellants. Most of the known ferrocene-containing combustion moderators, however, display the unwanted property of migration, i.e. they travel out of the rubber-like binder matrix of the solid propellant into the surrounding insulation material, which leads to an uneven combustion and to a worsening of the resistance to ageing of the solid propellant.
In order to solve this problem, relatively complex ferrocene, derivatives were developed, which have a clearly reduced migration behaviour, or even none at all, such as, for example, so-called butacene (see EP 0 169 130 and BP 0 171 307). Apart from the difficult and complex preparation processes, these derivatives, in comparison with the migrating ferrocene derivatives, display a worse combustion as combustion moderators.
Developments (for example U.S. Pat. No. 3,932,240) for binding ferrocene derivatives having terminal hydroxyl groups or isocyanate groups by reaction to the plastic matrix of the solid propellants also exist. However, these combustion moderators also display an unsatisfactory combustion.
The object of the present invention is to make available ferrocene dicarboxylic acid diesters which, in solid propellants, have no tendency to migrate and nevertheless have a good to excellent combustion behaviour. In particular, they are to be suitable as combustion moderators for solid propellants. Furthermore, they are to have a low viscosity and a low vapour pressure.
This object was achieved in accordance with the invention by ferrocene dicarboxylic acid diesters having the general formula
in which X is an oligoethylene glycol radical having 2 to 20 ethoxy units and/or an &agr;,&ohgr;-alkyldiol radical having 2 to 8 C atoms.
Of the ferrocene dicarboxylic acid diesters in accordance with the invention, those in which X is an oligoethylene glycol radical having 2 to 4 ethoxy units are particularly preferred, This compound has particularly favourable properties, in particular with respect to the viscosity and the vapour pressure. For the same reasons, of the ferrocene dicarboxylic acid diesters in accordance with the invention that have an &agr;,&ohgr;-alkyldiol radical, the compounds in which the alkyldiol radical has 2 to 8 C atoms are particularly suitable. In this connection, the aliphatic chain of the alkyldiol radicals having 3 to 8 C atoms can even be branched. However, compounds having a linear carbon chain are preferred.
A suitable way for preparing the ferrocene dicarboxylic acid diesters in accordance with the invention is the synthesis by way of the ferrocene di(carboxylic acid chloride). As a rule, an excess of the corresponding diol or glycol compound is used in this connection. However, a process which starts from the corresponding ferrocene dicarboxylic acid is preferred. As a rule, a stoichiometric excess of the diol or glycol compound is used here as well.
Usually, as a result of the low carbonyl activity, carboxylic acids generally react only slowly with alcohols. By adding catalysts, usually typical esterification catalysts, in particular anhydrous hydrogen chloride, the esterification can be accelerated considerably. In this connection, the reaction mixture can be saturated with dry hydrogen chloride gas at the start of the reaction, or dry hydrogen chloride gas can even be passed through the reaction mixture throughout the entire reaction.
The ferrorene dicarboxylic acid diesters in accordance with the invention can be used in solid composite propellants, among other things.
A further object therefore consisted in preparing solid composite propellants which do not have the disadvantages of the solid composite propellants known from the prior art but which distinguish themselves by an improved combustion behaviour.
This object was achieved in accordance with the invention by a solid composite propellant having the features of claim
6
. Advantageous developments are characterised in claims
7
to
25
.
Because the ferrocene dicarboxylic acid diesters in accordance with the invention have a liquid and not too highly viscous consistency and can be mixed with the binder polymers of the solid composite propellants and have, by way of their terminal OH groups, an unambiguously reproducible bonding functionality with constant equivalence values, they ensure a uniform casting viscosity for the fully mixed propellant slurry without negatively influencing the hardening reaction or the pot time. Moreover, they display no substantial impairment of the rubber-like properties of the binder polymers, for example by increasing the cross-linking density. They are oxidation-stable in the solid composite propellant matrix, so the stability of the solid composite propellant is not impaired The safety-related properties of the solid composite propellant are not negatively influenced by the binding in of the substances in accordance with the invention.
The ferrocene dicarboxylic acid diester derivatives in accordance with the invention are used as combustion moderators in the solid composite propellant. In this connection, the binding agent used in the solid composite propellant fixes the ferrocene dicarboxylic acid diester derivatives in accordance with the invention by way of their terminal hydroxyl groups.
Suitable polymer binders for the solid composite propellants in accordance with the invention consist of pre-polymers having terminal hydroxyl groups, which are converted with suitable linking reagents to form the actual binding agent. Examples of such pre-polymers are polyurethane binders such as polybutadiene (HTPB), polyester polyols or polyether polyols. Coupling reagents to be used are, for example, bifunctional or trifunctional isocyanates, preferably isophoron diisocyanate (IPDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI) or mixtures of the same. Particularly preferably, toluene diisocyanate (TDI) is used, In order to improve the network formation, when bifunctional isocyanates are used, low-molecular triols, for example trimethylolpropane, trimethylolethane or 1,2,4-butane triol, trifunctional polyethers orpolyesters can be used in a molar concentration corresponding substantially to the ferrocene dicarboxylic acid diester derivative, As polyurethane pre-polymers, preferably polybutadienes (HTPB) having terminal hydroxyl groups having an average molecular weight of 400 to 4,000, preferably 1,000 to 3,000, come into question.
In addition to these binding agents consisting of pre-polymers having terminal hydroxyl groups and the bifunctional or trifunctional isocyanates, polymer binders consisting of a cross-linkable mixture of hydroxyl-group-containing polymers and a polymer based on a 1,3-butadiene having lateral-position succinic anhydride groups have proven to be particularly suitable. These polymer binders harden in the presence of heat. The use of such polymers as binding agents for propellant bodies is described in DE-PS 38 09 297. The hydroxyl-group-containing polymer generally has an average molecular weight of between 1,000 and 10,000 and a hydroxyl number between 5 and 200 [mg KOH/g]. A hydroxyl-group-containing polybutadiene is particularly preferred. Other hydroxyl-group-containing polymers which are liquid at room temperature can also be used. These include the polyester polyols or polyether polyols already mentioned above, the polyethylene polyols or the polypropylene polyols. The reaction partner based on the 1,3-butadiene having lateral-position
Gottlieb Klaus
Hebekeuser Hans-Peter
Jungbluth Hubert
MacKowiak Hans-Peter
Neitsch Horst
Antonelli Terry Stout & Kraus LLP
Dynamit Nobel GmbH Explosivstoff - und Systemtechnik
Nazario-Gonzalez Porfirio
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