Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-07-01
2004-11-09
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S319000, C526S326000, C526S329700, C526S334000, C526S091000, C526S229000, C526S217000, C520S001000
Reexamination Certificate
active
06815517
ABSTRACT:
FIELD OF INVENTION
The object of the present invention is a mortar composition of at least two components curable by heat initiation, containing at least one polymerizable monomer and/or at least one curable resin, at least one polymerization initiator for the polymerizable monomer and/or the curable resin and, optionally, at least one filler, as well as a method for fastening tie rods, reinforcing steel for concrete or the like in solid substrates using this mortar composition.
BACKGROUND INFORMATION AND PRIOR ART
Normally, two-component mortar compositions, based on methacrylates or epoxide resins, are used to fasten tie bars, reinforcing steel for concrete or similar elements in a borehole in mineral substrates. These mortar compositions, after their constituents, which react with on another, are mixed, have a certain pot life, during which the element, which is to be fastened, can be set and, at the end of a further time span, reach their ultimate strength. Under ordinary conditions, said pot life is of the order of a few minutes. The curing usually takes place within a few minutes to a few hours. In any case, the two effects are coupled to one another, that is, a longer pot life leads to a longer curing time. Furthermore, these times may vary, depending on the conditions of the surroundings, especially on the temperature.
In order to overcome this temperature dependence, the older German patent application 100 02 367.3 proposes a mortar composition, which can be cured by frontal polymerization after thermal initiation and which contains, aside from a polymerizable monomer or curable resin and, optionally, at least one filler, a polymerization initiator for the monomer, which can be activated at a temperature above 30° C., and/or a polymerization initiator for the monomer, which can be released thermally, and/or a curing accelerator for the curable resin. The nature and amount of monomers or resin and polymerization initiator or curing accelerator are selected so that, after the polymerization is initiated, the polymerization front has a speed of at least 10 cm/min (frontal speed).
U.S. Pat. No. 6,057,406 discloses that, for the frontal polymerization of a monomer mixture, tricapryl-methylammonium-persalfate an initiator can be used which has the advantage that gases are not formed during the decomposition. However, this very reactive polymerization initiator leads to an initiation of the polymerization already during the storage of a mixture of the initiator with polymerizable monomers.
Moreover, there is basically, that is, for frontal polymerization as well as for other methods of thermally initiated, free radical polymerization, a contradiction between the shelf life of the material to be used and the necessary high reactivity of the composition. For this reason, it is customary to formulate mortar constituents in two components and to combine either a less reactive initiator in one component with an accelerator in the second component or to store the active initiator in an inert substance (usually a plasticizer) separately from the polymerizable monomer or resin.
The amount of plasticizer used must be kept low, as it affects the mechanical properties of the cured mortar. This leads to mixing ratios of 1:10 to 1:7, which are disadvantageous for homogeneous mixing. For this reason, different procedures were proposed for using reactive carrier substances, which, in turn, make special reactants necessary in the other component.
Accordingly, the use of water as carrier substance has already been proposed. On the other hand, the WO-A-94/19397 discloses the use of epoxide and/or isocyanates as carrier material.
OBJECT OF THE INVENTION
However, since such carrier materials are expensive and disadvantageous, because reactions with the other components of the mortar composition may result, it is an object of the present invention to indicate a mortar composition, which can be cured by thermal initiation, does not require any additional carrier materials for the polymerization initiator, solves the problem of the homogeneous mixing and, while having a good shelf life, has a high reactivity and leads to homogeneously cured end products of high mechanical strength.
SUMMARY OF THE INVENTION
Thermal initiation is understood to mean that the polymerization reaction of the mortar composition, obtained by mixing the constituents present in the separate components, can be initiated at any time after the mixture is formed, by supplying heat so that the pot life of the mortar composition is very long and the curing can be started selectively at any time. By these means, it becomes possible initially to charge a large number of boreholes with the mortar composition, subsequently to insert and adjust the fastening elements and then to initiate the curing, so that it becomes possible to achieve an optimum and largely identical curing and, with that, largely identical pull-out strengths for the installed fastening elements.
Surprisingly, it has now turned out that it is possible to accomplish this objective in a very simple and elegant manner owing to the fact that, as polymerization initiator, an organically substituted ammonium persulfate is used, which, however, is present only in the form of the required starting materials in separate components of the mortar composition and is formed only in the mortar composition when the at least two components are mixed in situ. In this connection, one component of the mortar composition contains at least one organically substituted ammonium salt, while a different component contains at least one inorganic persulfate, which forms the organically substituted ammonium persulfate by a very rapid reaction, which is then available as initiator for the free radical curing of the mortar composition.
An object of the invention therefore is an at least two-component mortar composition of claim
1
, which can be cured by thermal initiation The dependent claims relate to the preferred embodiments of this object, as well as to a method for fastening elements, such as tie rods, reinforcing steel for concrete or the like in solid substrates using this mortar composition.
The invention therefore relates to an at least two-component mortar composition, which can be cured by thermal initiation and contains
a) at least one polymerizable monomer and/or at least one curable resin,
b) at least one polymerization initiator for the polymerizable monomer and/or the curable resin and
c) optionally at least one filler, wherein, as polymerization initiator, at least one organically substituted ammonium salt is contained as constituent of a mortar component and at least one inorganic persulfate is contained as constituent of a further mortar component, which, after the mortar components are mixed in situ, results in an organically substituted ammonium persulfate, the nature and amount of the organically substituted ammonium salt and inorganic persulfate as well as of polymerizable monomer or curable resin being selected in such a manner, that a mortar composition results, which can be polymerized by free radical polymerization due to the action of heat.
In accordance with a preferred embodiment of the invention, the mortar composition contains
a) 10 to 98% by weight of at least one compound (A), which has at least one polymerizable vinyl group, as polymerizable monomer or curable resin,
b) 1 to 15% by weight of at least one organically substituted ammonium salt (B)
c) 1 to 15% by weight of at least one inorganic persulfate (C)
d) 0 to 60% by weight of at least one filler (D)
e) 0 to 10% by weight of at least one thickening agent (E)
f) 0 to 30% by weight of at least one further polymerization initiator (F), which can be activated thermally and/or released thermally at a temperature above 30° C. and has a self-acceleration decomposition temperature (SADT) of at least 30° C., for the vinyl compound (A)
g) 0 to 10% by weight of at least one polymerization accelerator (G) and
h) 0 to 10% by weight of at least one solvent or diluent (H), the organically substituted ammonium salt (B)
Böck Marianne
Bürgel Thomas
Hilti Aktiengesellschaft
Sastri Satya B
Sidley Austin Brown & Wood LLP
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