Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-12-17
2001-11-13
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S459000, C523S466000
Reexamination Certificate
active
06316529
ABSTRACT:
DESCRIPTION
1. Technical Field
The subject matter of the present invention is a two-component coating agent based on epoxy resin that is especially suited for cement-bound backgrounds.
2. State of the Art
In the past, self-leveling, filled and/or pigmented coating materials based on epoxy resin have proven themselves well for the coating of cement-bound backgrounds such as, for example, industrial floors, warehouses and traffic surfaces that are heavily walked or driven upon and walls which are exposed to weathering conditions and/or chemical influences. In particular, the mechanical and chemical resistance can be distinctly increased with coatings of this type.
In this connection, increasing chemical resistance against aggressive gaseous or liquid medium chiefly stands in the fore-ground but also improving crack bridging properties that, above all, should prevent leakiness which is caused by cracks in the background.
Particular demands are placed on the epoxide resin-based coating systems in special fields of application in which regulations are to be observed such as, for example, the Construction and Testing Rules (“Bau- und Prüfungssätze”; BPG) of the German Institute for Civil Engineering. Hence, among others, this regulation for coating systems that are to be used in warehouses in which water-endangering liquids are held requires a static crack bridging capacity of at least 0.2 mm with an as high as possible chemical resistance at the same time. The total resistance of the coatings are tested with special test liquids over a time period of 42 days and under an applied pressure of one bar. The standardized test liquids represent certain groups of possible stock chemicals such as, for example, inorganic bases or acids, organic acids, esters, ketones, alcohols or aromatic hydrocarbons.
In order to meet the posed requirements, various epoxide resin coating systems have been developed which are all composed of several individual layers.
The simplest coating system consists of a primer and an elasticized covering layer; however, this system has only a very limited durability.
After that, systems were developed that possess an intermediate layer between the primer and a rigid, highly cross-linked covering layer which is meant to guarantee the resistance. For crack bridging, this can either be elastic or can consist of a laminate layer with fabric or non-woven inserts.
Only with the multi-layered systems has it been possible up to now to combine the crack bridging capacity with the resistance against certain chemical test groups required by regulations, whereby the quality is still unsatisfactory. In addition, the high price and the extreme laying effort negatively burden the economic efficiency of these systems.
Up to now, mostly coating systems based on epoxide resin have been used which typically contain epoxide resins with a molecular weight <700 g/mol, such as bisphenol A and/or F, reactive diluents and polyamine-based hardener formulations as components. In this connection, the hardener can be pre-added to a certain degree and contains amines such as 3-aminomethyl-3,5,5-trimethyl cyclohexylamine (IPDA), diaminodiphenylmethane (DDM), bis-paraaminocyclohexylmethane (PACM)), 1,3-bis(aminomethyl)cyclohexane(BAC) or triethylenetetramine(TETA).
With coating agents that contain these amines individually or in mixtures, cracks <0.2 mm can be bridged by simultaneously covering a large number of test groups (including solvents) (type A) or cracks ≧0.2 mm, whereby, however, only a small number of test groups (without solvents) are covered (type B). In the later case, extenders (liquid fillers) and/or resins and/or hardeners with long-chained structures are typically added to the coating agents for elastification.
In all, it is to be assumed that coating systems that meet the requirements of DIBT (German Institute for Civil Engineering) test groups 3, 8, 10 to 12 and 14 only have a low resistance; that which fulfils the test groups 1, 2 and 9 meets average demands and high demands are fulfilled by meeting the requirements of the test groups 4 to 7 and 13.
In order to improve the requirement profile of the coating systems, accelerators or highly reactive amines, above all m-xylylenediamine (MXDA), are also added to the epoxide resin mixtures in addition to the above mentioned components. The use of MXDA as a hardener component in mixtures with tertiary amines is also known; however, in these relatively seldom cases which are only limited to special uses, rigid coating materials are always obtained with a high elastic (E) modulus as well as intense embrittlement phenomena in the hardened coating agent as well such that an elastic crack bridging with these MXDA containing hardener mixtures was not possible.
Therefore, the object from the described short-comings of the state of the art was to develop a two-component coating agent based on epoxide resin that guarantees an elastic crack bridging without embrittlement phenomena and, at the same time, has a very high chemical resistance, whereby laminar intermediate layers can be dispensed with for simplified working properties.
SUMMARY OF THE INVENTION
This object was solved with a two-component coating agent based on epoxide resin with a resin component A and a hardener component B, characterized in that the resin component A comprises 15 to 80% by weight, in relation to the component A, of an epoxide resin and at least at one additional component selected from a reactive diluent, a filler, other ingredients such as pigments, additives and extenders, and the hardener component B comprising 20 to 50% by weight, in relation to component B, of m-xylylenediamine and at least one additional component selected from an adductor resin, an extender and an accelerator, and that the components A and B are present in a molar ratio of 1:0.8 to 1.2.
It was completely surprising to find that by maintaining the above quantitative proportions and by exclusive use of m-xylylenediamine as a hardener component and/or by a large excess of MXDA in relation to the total amine content in the hardener, the crack bridging properties can be combined very well with an extremely high chemical resistance. In addition, it was also shown that layer thicknesses of several centimeters can be durably built-up with coatings according to the invention that are possible without the effort associated with installation of floating or laminate layers which was not to be expected to this degree.
BEST MODE FOR CARRYING OUT THE INVENTION
For the effects that are to be achieved by the present invention, it has proven itself favorable when epoxide resins of the type bisphenol A and/or F are preferably used for the resin component A. The amount of epoxide resin can be 15 to 80% by weight, preferably 20 to 60% by weight.
As already mentioned, further components in varying portions can be present in both components A and B of the coating agent according to the invention aside from the main components of epoxide resin and m-xylylenediamine that are essential for the invention.
Thus, it has been proven favorable for certain applications when the reactive diluents are added to the coating agents whereby the viscosity is adjustable and the total chemical resistance of the coating material is controllable, especially in component A. The use of reactive diluents for the preparation of component B positively influences the viscosity of the total hardener component. Typical reactive diluents according to the invention are epoxide group-containing mono-, di- or polyfunctional ethers, preferably of the type hexanediol-, neopentyl diglycol and trimethylolpropane triglycidyl ethers. However, other representatives are considered, for example, cresyl glycidyl ethers, n-dodecyl or n-tetradecyl glycidyl ethers, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether or cyclohexane dimethanol diglycidyl ether. If a reactive diluent is contained in component A, its amount is preferably up to 30% by weight, for example, 3 to 20% by weight.
As also mentioned above, large layer thickn
Krausche Christian
Pretz Thorsten
Temme Werner
Aylward D.
Conica Technik AG
Dawson Robert
Goldberg Joshua B.
Nath Gary M.
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