US2041234A - Bituminous dispersions for coatings or coverings and a process of preparing them - Google Patents

Description

' the like, as coatings for sheets, roofs, for bituminous linings of tubes, walls, shafts, chimneys or Patented ay re, 1936 TES NT OFFICE EARING THEM Karl Daimler, Frankfort-on-the-Main-Hochst, Germany, assignor to 1. G. Farbenindustrie Aktiengesellschaft, Gery Frort on the Main,

No Drawing. Application January 2, 1931, Serial No. 506,316. in Germany January 30, 1939 3 illaims.

I have found that dispersions for coatings or coverings can be prepared by mixing high-melting bitumen and low-melting bitumen in the form of a stable'dispersion at a temperature which is below the softening point of the low-melting bitumen. These dispersions contain high-melting bitumen and low-melting bitumen side by side, i. e., the particles of the different bitumens are not combined by dissolution or melting together. During the storage of the dispersion the dissolution of the particles of high-melting bitumen in those of low-melting bitumen is prevented by the dispersion Water so that no uniform dissolution product of an average melting temperature is produced. g

These dispersions are used, if required mixed with comminuted stone, such as chips, sand and ,for the preparationof bituminous mortar masses,

riation of temperature. When preparing road coverings one can proceed in the usual manner; either by applying the asphalt dispersions on the roads and subsequently covering them with chips or sand or by mixing finely broken stones, chips and sand in a mixing machine with ltheyasphalt dispersion and spreading the mixed mass in a thickness of several centimeters on the road and compressing it either by rolling or ramming.

When the dispersions are allowed to dry, the particles keep their characteristic feature, this being a surprising fact. The particles a lutinate with each other but they do not mix in the sense of yielding a uniform solution. A coating or a bituminous film produced from these mixed dis-= persons can be imagined as a mosaic wherein the low-melting particles fulfil their function as an elastic adhesive even in the severe cold whereas the high-melting particlesact nearly as an inert filler constituent. in summer these high-melting particles prevent the covering running too much and getting soft, as the particles hen show the highest degree of elasticity ,adhesiveness when the low-melting particles have already become liquid. Even in midsummer a suficient viscosity of the cementing cover of the mineral material is thus guaranteed.

It may be particularly advantageous to use mixed dispersions which contain such dispersing agents as are no longer affected or redissolved by water after the dispersion has been allowed to dry once. It may become important for the process whether the dispersions which are to be united contain the same or difierent dispersing agents and at which time the dispersions are united whether before or while being worked up.

During the manufacture and storing of the mixed dispersions one must proceed in such a. manner that a mixing of the low-melting with the high-melting bitumen is excluded. Temperatures above the softening point have likewise to be avoided as much as possible. The process is, therefore, preferably carried out as follows: The ready made cold asphalt with low-melting bitumen is mixed at ordinary temperature with ready"made cold asphalt which is prepared from high-melting bitumen. While observing particular precautions and very low dispersing temperatures the two bituminous substances may be dispersed together simultaneously in the same vessel without their dissolving or mixing with each other.

The following examples serve to illustrate the invention, but they are not intended to limit it thereto, the parts being by weight:

(1'). 200 parts of a bituminous dispersion of 50 per cent strength prepared from petroleum asphalt having a softening point according to Kramer-Sarnow of 50 C.-60 C. are mixed at ordinary temperature with 100 parts of a 50 per cent dispersion of petroleum asphalt. prepared from petroleum asphalt of the softening point according to Krdmer-Sarnow of (1-30 C.

The product serves for painting gutters or for coating roofs which, if they are to be walked on, are subsequently covered with sand.

into 208 parts of a per cent paste of finely ground lignite containing humic acid there are caused to run at a temperature of between 40 C. and 50 C. the fused mass of 500 parts of petroleum asphalt having a temperature of 80 C. and a softening point according to Kramer- Sarnow of 50 C.-60 0., while vigorously stirring and adding 300 parts oi cold water in such a manner that the temperature of the dispersion produced never exceeds 50 C. The mixture is then cooled to 30C. so that the particles of the petroleum pitch melting at 50 C.-60 C. are always below their softening point and are thus present in the dispersion in solid form surrounded by water. Into the dispersion there are caused to run the fused mass of 500 parts of road making tar having a temperature of about 50 C. while cooling the impregnating vessel and vigorously stirring, in such a mannerthat the content of the vessel does not rise above 30 C. Partly simultaneously, partly after the addition of the tar there are added 500 parts of cold water. During this method of working the road making tar is converted into very fine particles which are surrounded from all sides by water and which, therefore, cannot be united with the solidified particles of petroleum pitch likewise surrounded by water. Even during the storage and use of these mixed dispersions the two kinds of bituminous components cannot be united with each other, this being prevented on the one hand by the water-cover of the various particles, on the other hand by the temperature which is constantly kept below the softening point of the petroleum pitch.

The mixed dispersion thus obtained is spread upon a well cleaned macadamized road and well coated. The road is then covered with basalt chips. The process may be repeated several times, if required.

(3) A mixture containing 30 parts of finely ground chips (2-3 cm.), 30 parts of chips (granular size 5-8 cm.),'30 parts of sand, 10 parts of pulverized basalt, all products in the natural moist condition, is intimately mixed with 10 parts of the bituminous dispersion prepared according to Example 2. This mixture is particularlysuitable for the preparation of mixed covers. For this purpose the mixture is poured upon the road and uniformly spread by means of a rake and then compressed by rollers so as to form a layer having a thickness of 3-4 cm'.

I claim:

1. The method of insuring the binding actio 'of asphalt which is applied as an asphalt emulsion to serve as a binder in the construction of highways, which method comprises incorporating in a hard asphalt emulsion an independent emulsion of a softer, solid, bituminous material fluxible with said hard asphalt, and preventing the fluxing of the softer, bituminous material with said hard asphalt whilepresent in the emulsion by means of a dispersing film which prevents coalescence until the emulsion has dried or has been broken, whereby a better binding is effected when the emulsion is dried or broken than could be effected by the use of a simple emulsion of the hard asphalt and the soft bituminous material.

2. An aqueous asphalt emulsion consisting essentially of a hard asphalt in an aqueous phase in the form of rounded solid asphalt particles separated from the continuous aqueous phase by an interfacial film and a lower melting solid asphalt likewise dispersed in an aqueous phase in the form .of rounded particles separated from the continuous phase by an interfacial film, the hard asphalt and the lower melting asphalt being dispersed in the same aqueous phase whereby the interfacial films on the hard asphalt particles and the lower melting asphalt particles respectively prevent the fluxing of the hard asphalt with the lower melting asphalt'prior to the breaking of the emulsion.

3. An aqueous asphalt emulsion consisting essentially of a small amount of an emulsifier, about 25% to about 33% of a hard asphalt in an aqueous phase in the form of roundedsolid asphalt particles separated from the continuous aqueous phase by an interfacial film and about 16% to about 25% of .a lower melting solid asphalt likewise dispersed in an aqueous phase in the form of rounded particles separated from the continuous phase by an interf'acial film, the hard asphalt andthe lower melting asphalt being dispersed in the same aqueous phase whereby the interfacial films on the hard asphalt particles and the lower melting asphalt particles respectively prevent the fluxing of the hard asphalt with the lower melting asphalt prior to the breaking of the emulsion.

KARL DAIMLER.