Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-05-07
2002-09-17
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S059000, C106S277000, C106S668000, C106S670000
Reexamination Certificate
active
06451885
ABSTRACT:
The present invention relates to stabilised bitumen emulsions and their incorporation into composite compositions comprising either hydraulic or organic binders, or inorganic fillers, or a mixture of these components. The present invention relates more particularly to surfactant-stabilised aqueous emulsions of bitumen, and compositions formulated from such emulsions and designed to be incorporated at the time of use into the above components, for use in the building industry or civil engineering, and notably mortar-adhesive compositions, seams for roads and highways, paints, mortars for flooring, coatings and concretes.
The formulation of mortar-adhesive type products, coatings for outer facings, paints, coatings for finishing floors, etc comprises a basic binder, generally hydraulic or organic, to which the various additives, or even other binders, are added, to improve, among other things, rheological properties (facilitating implementation), mechanical characteristics, and drying characteristics. Frequently, when hydraulic binders are used for example, polymers are incorporated for improving mechanical strength characteristics, flexibility, and ability to withstand deformation. In the case of hydraulic binders, this polymer is generally in the form of a polymer in emulsion or in dispersion (latex, for example). This additive represents a non-negligible supplementary cost in such formulations, which it is desirable to reduce.
The question of using bitumen in emulsion, known to be inexpensive, has frequently been posed, but great difficulties in achieving formulations in the fields of application applicant is aiming at were encountered, as:
a bitumen emulsion that is stable over a long period must be provided, notably stable for more than six months, before mixing it with products which are frequently in powder form, whether or not pre-formulated, in the dry state, meaning that the complete product should be able to be stored in the form of a kit of components;
the hydraulic binders or inorganic fillers of the formulation flocculate or cause the emulsion to flocculate during mixing therewith;
the formulations to be provided do not achieve the desired characteristics or the formulations are too complex or expensive to be employed in practice.
The applicant has consequently set out to obtain bitumen emulsions which can meet these objectives, having universal suitability for incorporation, without breaking the emulsion, into formulations, for example for construction, which are easy to implement, in other words, notably, not presenting problems of delaying or accelerating setting.
Bitumens are mixtures of heavy hydrocarbons, essentially naphthenic and paraffinic, originating from the distillation of crude oils. These products are distillation residues and are classified by their physical properties, their chemical properties varying very widely as a function of the origins of the crude. Generally speaking, conventional crudes contain up to 30% bitumen, and heavy crudes up to 50%. As bitumen requirements of the majority of countries represent 2 to 4% of their crude oil consumption, this means that bitumen is available in very plentiful supply. Bitumens contain such a diversity of constituents that it is impossible to define their exact composition; nevertheless, it is possible to classify these constituents into major chemical families:
saturated compounds, essentially paraffinic;
aromatic compounds, in which 30% of the carbon atoms are included in aromatic cycles, with a sulphur content of around 2 to 3%;
asphaltenes, which are insoluble in hydrocarbons, are aromatic and rich in sulphur, nitrogen, and oxygen; they take the form of black brittle solids practically incapable of being melted.
For given bitumens, the percentage of these various families depends heavily on the extraction method used. Thus, products of this type are essentially classified by the following physical properties: penetrability (NFT 66-004), softening point (NFT 66-008), density (NFT 66-007), flashpoint (NFT 60-118), solubility (NFT 66-012) ductility (NFT 66-006), brittleness point. Commercially available bitumens, classified by penetrability index, are generally situated between 10 and 200. Currently, only two grades are able to remain emulsified at atmospheric pressure, the 80/100s and 180/220s, but it is possible, in certain cases, to emulsify 40/50 grade.
Like all materials, bitumen is sensitive to fatigue, and consequently its breaking strength can fall when subject to repeated stresses. As against this, it has a self-repairing capability allowing the destructive effects of fatigue phenomena to be limited. It is known to improve the flexibility properties of some bitumens by mixing them with synthetic elastomers such as styrene-butadiene polymers or atactic polypropylene.
Bitumen emulsions were developed for making cold coating compounds, some 60 years ago, and numerous articles and patents disclose bitumen emulsions manufacture by associating several surfactants of different natures. The three main types of emulsion are:
cationic emulsions, in which the surfactants are constituted by polar molecules of formula RNH3
+
X
−
, R being the hydrocarbon chain constituting the lipophilic portion of the molecule, and NH3
+
X
−
the hydrophilic portion, X
−
being any anion whatsoever of a strong acid.
anionic emulsions of general formula R—Y— C
+
, R being the hydrocarbon chain constituting the lipophilic portion, and Y
−
C
+
being the hydrophilic portion, Y
−
being a carboxylic, sulphonic, sulphuric, phosphonic or phosphoric group, C
+
being a metal cation, frequently alkaline, or ammonium;
non-ionic emulsions, in which the surfactants are constituted by molecules of the R—(EO)
n
—OH type, in which R is the hydrocarbon chain constituting the lipophilic portion of the molecule, the hydrophilic portion being constituted by the —(EO)
n
—OH radical (EO signifying ethylene oxide). The most frequently encountered bitumen emulsions are however cationic or anionic emulsions.
The surfactants employed for obtaining these emulsions are chosen so as to stabilise the emulsion during the period of storage, which frequently is not very long, for example only a few weeks, in the case of emulsions for roads and highways for carrying out cold coating. Moreover, it is frequently necessary to add components other than surfactants such as thickeners, to improve their stability.
Generally speaking, bitumen emulsions are made hot, by mixing, continuously or discontinuously, the two pre-heated phases (water at 50° C., bitumen from 140° C. to 170° C.) using a disperser, the emulsifying surfactant being able to be introduced previously into either the aqueous or bitumen phase. Examples of known emulsions obtained in this way are given below in table 1:
TABLE 1
Anionic emulsion
cationic emulsion
80/100 bitumen: 55%
180/220 bitumen: 65%
Sodium dodecylbenzene
propylene diamine of tallow
sulfonate: 3%
(Dinoram S): 2 g/l
hydrochloric acid up to
pH = 2.0 to 2.5
gelling agent (Nopco DSX
1550): 1.75 g/l
Water: 42%
water: 35%
The bitumen emulsions thus obtained are used in many different ways. For example, in the road making field, it is known to “provoke breakage” of the bitumen emulsion by introducing a small amount of a cement into it the sole effect of which is to cause the medium to flocculate and improve departure of water. These emulsions are, in effect, formulated so as to provoke their destabilisation in the presence of inorganic granulates or powers (e.g. silica, chalk, cement). The most common applications of these types of emulsions are bituminous beds or base courses, cold surfacing materials, bituminous slurries, and keying and waterproofing layers. Applications other than road making are essentially those of sealing compounds for dams and canals in civil engineering as well as roof and foundation waterproofing in the building industry.
Cationic surfactants, (like amphoteric surfactants) cannot be used where it is desired to mix the bitumen emulsions and a hyd
Dresin Jean-Marc
Picard Nadège
Siaud Brice
Stock Claude
Kenyon & Kenyon
Lafarge
Szekely Peter
LandOfFree
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