Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-12-21
2004-03-09
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S425000, C524S788000, C525S454000, C525S477000, C528S012000, C528S014000, C528S033000, C528S034000, C528S038000, C528S041000, C528S043000
Reexamination Certificate
active
06703453
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to polyurethane compositions which cross-link via a silane polycondensation and contain at least one alkoxysilane-functional polyurethane, at least one basic filler, at least one reaction product of an aminosilane with a maleic or fumaric ester, at least one organometallic compound and optionally additional auxiliary substances, to a process for their preparation, and to their use.
Alkoxysilane-functional polyurethanes which cross-link via a silane polycondensation are part of long-known prior art. A survey of the topic is to be found in “Adhesives Age” 4/1995, page 30 ff. (authors: Ta-Min Feng. B. A. Waldmann). Such alkoxysilane-terminated, moisture-curing one-component polyurethanes are increasingly being used as flexible elastic coating, sealing and adhesive compositions in the construction industry and in the automobile industry. For these applications, high demands are placed on the extensibility, the adhesive power and on the speed of cure.
Such products are described by way of example in EP-A 596360, EP-A 831108, EP-A 807649 or in EP-A 676403. Organometallic catalysts as well as adhesion promoters of the aminosilane type are commonly used concomitantly in the formulation of systems of this kind. But the addition of aminosilane compounds can often lead to problems with stability in storage, particularly when higher proportions of aminosilanes are used in order to achieve a good adhesion to difficult substrates.
Accordingly, the object of the present invention was to provide polyurethane compositions which cross-link via a silane polycondensation, contain aminosilanes and have an improved stability in storage.
This object was achieved by the provision of the polyurethane compositions which cross-link by condensation described in more detail below.
SUMMARY OF THE INVENTION
The invention provides polyurethane compositions which cross-link via a silane polycondensation, containing
A) at least one alkoxysilane-functional polyurethane having end groups corresponding to the general formula (I)
wherein
R
1
represents an organic group having 1 to 12 carbon atoms,
n is an integer from 2 to 4 and
X, Y, Z denote identical or different organic groups, with the proviso that at least one of the groups is an alkoxy group having 1 to 4 carbon atoms, preferably a methoxy or ethoxy group,
B) at least one basic filler,
C) at least one reaction product of at least one aminosilane corresponding to the general formula (II)
wherein
R
2
represents a hydrogen atom, or an aminoethyl group and
n, X, Y, Z have the meanings given for formula (I),
with at least one maleic or fumaric (ester) corresponding to the general formula (III)
R
3
OOC—CH═CH—COOR
3
(III),
wherein
R
3
represents an alkyl group having 1 to 12 carbon atoms,
E) at least one organometallic compound and
F) optionally additional auxiliary substances.
DETAILED DESCRIPTION OF THE INVENTION
The invention is based on the surprising observation that the adducts of aminosilanes with maleic or fumaric esters which, according to the invention, are used instead of the aminosilanes conventionally employed as adhesion promoters, bring about improved mechanical properties and an improved stability in storage.
The reaction products of maleic or of fumaric esters and aminosilanes which according to the invention are to be used as component C) are known in principle and are described by way of example in EP-A 596360 or EP-A 831108. According to the disclosures in these publications, the reaction products of maleic or of fumaric esters with aminosilanes are used for the reaction with isocyanate prepolymers. The use of these products as an additive for improving the mechanical properties and for improving the adhesion of polyurethanes which cross-link via silane polycondensation is hitherto unknown.
The polyurethanes having alkoxysilane end groups which according to the invention are to be used as component A) are known in principle and are prepared by reacting long-chain, preferably linear, NCO prepolymers with aminofunctional silanes corresponding to the general structural formula (II)
wherein R
1
represents an organic group having 1 to 12 carbon atoms, preferably a phenyl group or particularly preferably a group corresponding to the general structural formula (IIb),
wherein R
4
represents an alkyl group having 1 to 4 carbon atoms. In the above structural formula, n is an integer from 2 to 4, preferably 3.
X, Y, Z in the above structural formula denote identical or different organic groups, with the proviso that at least one of the groups is an alkoxy group having 1 to 4 carbon atoms. Preferably at least one of the groups is a methoxy or ethoxy group. Particularly preferably X, Y and Z each represent a methoxy group.
Examples of suitable aminofunctional silanes producing end groups corresponding to structural formula (I) are N-methyl-3-aminopropyltrimethoxysilane. N-methyl-3-aminopropyltriethoxysilane, N-butyl-3-aminopropyltrimethoxysilane. The use of N-phenyl-3-aminopropyltrimethoxysilane is preferred. It is particularly preferable to use the aspartic esters described in EP-A 596360. which are formed through the reaction of aminosilanes corresponding to the general structural formula (II) with maleic or fumaric esters corresponding to formula (III).
NCO prepolymers which can be used for the preparation of the polyurethanes A) having alkoxysilane end groups are prepared in known per se manner by reacting polyether polyols, preferably polyether diols, with diisocyanates and have an NCO content of between 0.4 and 4%.
Compounds which can be used as basic fillers B) are precipitated or ground chalks, metal oxides, metal sulfates, metal silicates, metal hydroxides, metal carbonates and metal hydrogen carbonates. Other fillers are, for example, reinforcing and non-reinforcing fillers such as, for example, pyrogenic or precipitated silicas, carbon black or quartz powder. Both the basic fillers and the other reinforcing or non-reinforcing fillers may optionally be surface-modified. Precipitated or ground chalks and pyrogenic silicas are particularly preferably used as basic fillers B). The component B) may, of course, also be mixtures of fillers.
Compounds used as component C) are reaction products of aminosilane compounds corresponding to the general structural formula (II)
wherein
R
2
, X, Y, Z and n have the meanings given above,
with maleic or fumaric (esters) corresponding to the general formula (III)
R
3
OOC—CH═CH—COOR
3
(III),
wherein
R
3
represents an alkyl group having 1 to 12 carbon atoms.
Examples of usable aminosilane compounds corresponding to formula (II) are 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-aminoethyl-3-amino-propyltrimethoxysilane, N-aminomethyl-3-aminopropyltriethoxysilane, 3-amino-propylmethyldiethoxysilane and N-aminoethyl-3-aminopropylmethyldimethoxysilane.
In formula (III), R
3
represents a linear or branched aliphatic hydrocarbon group having at most 12 carbon atoms. Examples of suitable maleic and fumaric esters are diethyl maleate, dimethyl maleate, dibutyl maleate, dioctyl maleate, diethyl fumarate, dimethyl fumarate, dioctyl fumarate.
In the case where the products in which R
2
in formula (II) denotes a hydrogen atom are used as aminosilanes, in the course of the reaction with the maleic or fumaric esters in accordance with the disclosure in EP-A 596360, aspartic esters corresponding to the general structural formula (IV) are formed
wherein
R
3
, X, Y, Z and n have the meanings given for formulae (II) and (III).
In the particularly preferred case, where products in which R
2
denotes an aminoethyl group are used as aminosilanes corresponding to formula (II), piperazinone derivatives corresponding to the general formula (V)
wherein
R
3
, X, Y, Z and n have the meanings given for formula (IV),
are formed through a cyclocondensation reaction.
All organometallic catalysts, which—as is generally known—promote silane polycondensation, can be used as component E). These are in particular
Lemmerz Ralf
Schmalstieg Lutz
Walter Marie-Hélène Marie-Ange Christiane
Walter Ulrich
Wilmes Oswald
Bayer Aktiengesellschaft
Gil Joseph C.
Matz Gary F.
Roy Thomas W.
Sergent Rabon
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