Release agents for bituminous substances

Details Release agents for bituminous substances Release agents for bituminous substances

2000-08-15

2003-01-14

Dawson, Robert (Department: 1712)

Coating processes

Coating pavement or the earth

Asphalt, bitumen, oil, or tar containing coating

C428S041800, C428S447000, C428S448000, C106S287100

Reexamination Certificate

active

06506444

ABSTRACT:

TECHNICAL FIELD
The invention relates to compositions, to a coating system comprising said compositions and to a process for producing such a coating.
BACKGROUND ART
Many bituminous compositions are in commercial use. Bitumens such as highway paving bitumens and industrial bitumens, bituminous binders, for example in the form of solutions and emulsions, and polymer-modified bitumens and asphalts, for example, natural asphalts and industrial asphalts, bitumen sheets, coal tar pitches, special-purpose coal tar pitches and formulations comprising special-purpose coal tar pitches such as highway pitches, coal tar binder pitches, coal tar impregnating pitches, prepared pitches, pitch suspensions and special-purpose coal tar pitches with minerals, are widely employed in asphalt, priming, insulating and leather coatings for use in the construction, electrical, paint, and coating industries. Since at conventional temperatures, bitumens, bituminous binders and asphalts are fairly solid and unaffected by water, they are used extensively to “asphalt” traffic areas, such as highways, lots and streets (in admixture with a large number of other materials), and roofs, and also to produce roofing felts.
The same properties which give bitumens, bituminous binders and asphalts their desired profile of properties, for example, toughness and outstanding adhesion to a great variety of different materials, cause significant problems in the course of their use in respect to their separation from surfaces with which they come into contact, such as truck beds and other transportation vessels, asphalting machines, road rollers, shovels, rakes and other tools.
These problems have intensified through the use of new kinds of asphalt compositions which are modified with organic polymers, for example, with synthetic or natural rubbers, thermoplastic elastomers, or thermoplastic resins, since these new kinds of asphalt compositions display increased adhesion to a very wide variety of surfaces.
Petroleum products such as diesel fuel, for example, have been and still are being used in the case of truck beds and other transportation vessels, asphalting machines, road rollers, shovels, rakes and other tools in order to facilitate the separation of bitumens, bituminous binders, asphalts, special-purpose coal tar pitches and formulations comprising special-purpose coal tar pitches from their surfaces. Diesel fuels in this application, however, are regarded as environmentally suspect. A further factor is that the release effect of diesel fuels subsides over time; the effectiveness may be inadequate in the case of relatively long journeys from the asphalt manufacturer to the asphalting project or, in particular, for the new kinds of asphalt compositions described above, such as silent (rubberized) asphalts, water-permeable asphalts, abrasion resistant asphalts, colored asphalts and high-viscosity asphalts. Furthermore, diesel fuel may incorporate itself into asphalt compositions, where it may lead to the formation of local soft spots and changes in color of the asphalt composition, especially as a result of subsequent migration to the surface of asphalted areas under the effect of heat and light. This is undesirable for asphalt compositions in general and especially so for colored asphalts. For these reasons, diesel fuels can no longer be recommended as asphalt release agents.
U.S. Pat. No. 4,078,104 describes asphalt release coatings comprising polydialkylsiloxanes such as polydimethylsiloxanes, which additionally contain from 0.1 to 90.0% by weight of aminofunctional silanes or siloxanes. The compositions can be applied in pure form with special spraying devices, or in solution in organic solvents, such as naphtha, for example. These compositions do have a release action but are expensive. The application of the pure composition requires special spraying devices, while application from solution in organic solvent is no longer acceptable from an environmental standpoint.
U.S. Pat. No. 5,494,502 describes the use of emulsions of animal or vegetable fatty oils, such as, for example, soybean oil, linseed oil, tung oil and olive oil, together with a surfactant with which the oil can be dispersed in water. The preferred mode of application involves foaming the release agent with a special foaming apparatus, which considerably limits ease of application. In addition, the release properties are distinctly limited. As soon as the water has evaporated from the formulation, the fatty oils soften the asphalt and cause it to stick more strongly to surfaces such as, for example, truck beds. Furthermore, emulsions are metastable systems which may become unstable, especially at high dilution, and may tend toward creaming and separation, which is a hindrance to application.
DISCLOSURE OF INVENTION
It is an object of the invention to improve the state of the art, and in particular, to provide an inexpensive, environmentally compatible release agent for bituminous substances and pitches which can be applied without the use of organic solvents and without special equipment, which is stable, and which displays outstanding (multiple) release properties with respect to hot bitumens, bituminous binders, asphalts, bitumen sheets, coal tar pitches, special-purpose coal tar pitches and formulations comprising special-purpose coal tar pitches, and, in particular, the new kinds of asphalts described above. These and other objects are achieved by the present invention. It has surprisingly been found that release agents for bituminous substances and pitches can be prepared from certain organopolysiloxanes as herein defined, and can advantageously be provided in the form of aqueous solutions.
BEST MODE FOR CARRYING OUT THE INVENTION
The invention provides a composition which comprises at least one organopolysiloxane in aqueous solution or dispersion, most preferably in the absence of additional dispersants. The organopolysiloxane may be an individual organopolysiloxane or a mixture of different organopolysiloxanes. The organopolysiloxanes carry functional groups to the extent that stable aqueous solutions, suspensions or dispersions can be obtained in the absence of additional surfactants or dispersants. The organopolysiloxanes can be linear, branched or resinous and are formed from units of the formulae R
3
SiO
1/2
(M units), R
2
SiO
2/2
, (D units), RSiO
3/2
(T units) and SiO
4/2
(Q units). Organopolysiloxanes containing T and Q units are branched. Organopolysiloxanes which include large proportions of T and Q units are organopolysiloxane resins. In the preceding formulae, R is a saturated or unsaturated, unsubstituted or substituted C
1
-C
60
hydrocarbon radical.
Examples of radicals R are alkyl radicals such as the methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and tert-pentyl radicals; hexyl radicals, such as the n-hexyl radical; heptyl radicals such as the n-heptyl radical; octyl radicals such as the n-octyl radical and isooctyl radicals such as the 2,2,4-trimethylpentyl radical; nonyl radicals such as the n-nonyl radical; decyl radicals such as the n-decyl radical; dodecyl radicals such as the n-dodecyl radical; alkenyl radicals such as the vinyl and the allyl radicals; cycloalkyl radicals such as cyclopentyl, cyclohexyl, cycloheptyl radicals and methylcyclohexyl radicals; aryl radicals, such as the phenyl and the naphthyl radicals; alkaryl radicals such as o-, m-, p-tolyl radicals, xylyl radicals and ethylphenyl radicals; and aralkyl radicals such as the benzyl radical, the alpha- and the &bgr;-phenylethyl radical. C
1
-C
18
hydrocarbon radicals are preferred. Particular preference is given to the methyl radical.
Examples of substituted hydrocarbon radicals as radical R are halogenated hydrocarbon radicals, such as the chloromethyl, 3-chloropropyl, 3-bromopropyl, 3,3,3-trifluoropropyl and 3,3,4,4,5,5,5-heptafluoropentyl radical, and also the chlorophenyl, dichlorophenyl and trifluorotolyl radicals; mercaptoalkyl radicals such as the 2-mercaptoethyl and 3-mercaptopropyl radicals;

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