US2342861A - Method of improving the adhesivity of bituminous compositions - Google Patents

Description

'from by rain and atmospheric conditions.

Patented Feb. 29, 1944 2,342,861 OFFICE.

METHOD OF IMPROVING THE ADHESIVITY OF BITUMINOUS COMPOSITIONS Lucien Hemmer. Notre Dame de Gravenchon, France, assignor, by meme assignments, to Standard Catalytic Company, a corporation of Delaware No Drawing. Application September 1, 1938, Serial No. 227,961. In France September 15, 1937 4 Claiml.

This invention relates to a process of increasing adhesivity of bituminous binders, particularly asphalt cutbacks and emulsionaby addition of heavy metal compounds of organic acids and products thereof.

Asphalt is used in road construction either in a form oi. a cutback or an emulsion. Since adhesiveness is a consequence of wetting power, it is important that the wetting power of a bituminous binder toward the mineral aggregate be as high as possible. In presence of water, adhesiveness depends upon the respective wetting powers of the water. and the bituminous binder toward the mineral aggregate; if the wetting power of water is higher than that of the binder, the former will displace the latter and prevent the bituminous binder from adhering to the surface of the stone. This usually occurs with acid or si- .liceous type of-mineral aggregates, such as quartzite, silex, porphyry, etc. If the road construction is carried out with wet mineral aggregate, a bitumen of an ordinary cutback or emulsion will not adhere sumciently to the surface of the mineral aggregate. Similarly, the bitumen will be displaced from the surface of the mineral aggregate by rain after the road is constructed.

An object of the present invention is to prepare bituminous binders, such as cutbacks or asphalt emulsions, that will adhere to the surface of the mineral aggregate and will not be displaced there- Another object is to treat all types of mineral aggregate s, both alkaline and siliceous types, so that they can be coated with bitumen of good adhesivity.

Bituminous binders for paving compositions and road building are usually prepared by fluxing asphalts of low. penetrations with non-volatile oils. Extracts obtained in solvent extraction processes for preparing lubricating oils are preierred for this purpose. Thus, forexample, an 85-100 penetration base stock which is employed in the manufacture of cutbacks may be obtained by blending 88% of a 21-30 penetration Colombian asphalt with 12% of a lubricating oil extract having 3 Engler viscosity at 100 C. Both the asphalt and the extract obtained from Colombian base stocks contain naphthenic acids. Thus, for example, the above-mentioned Colombian extract contains about 1.8% of naphthenlc acids and other organic acids. It has now been found that the adhesivity of bituminous binders prepared from such stocks is greatly improved by heating the same with a heavy metal oxide, such as, for example, litharge or other lead oxide, iron oxide, etc. The heavy metal oxide should be present in at least the theoretical amount required to react with the naphthenic acid present and preferably in excess. The oxide may be added to the asphalt stock during the reduction period, i. e. during the distillation step while preparing the asphalt of the desired penetration. It may also be added to the flux obtained by admixing the asphalt stock with the extract. Since the concentration of naphthenic and other organic acids is rather low, a satisfactory dispersion of litharge or other heavy metal oxide is only obtained if fairly high temperatures, say 180 C. or more, are used and vigorous mixing is employed for at least 30 minutes or more. In order to eliminate the excess of uncomb'ined heavy metal oxide, it is necessary to allow the hot mixture to stand and settle 'i'or about half an hour, alter which the asphalt flux can be separated from the excess of metal oxide by decantation.

A reaction temperature of about to C. may be used when a volatile solvent, such as kerosene or heavy cracked naphtha, is added to the flux and the finished cutback so obtained is treated with themetal oinde. In this case, howevenit is desirable to carry out the reaction and the settling under pressure on account of the volatility of the solvent. The cutback obtained by this method has substantially the same adhesivity as one prepared by adding 2% lead oleate.

According to a second method, only the extract used in the preparation or the asphalt flux is heated with the heavy metal oxide. The extracts usually contain higher percentages of naphthenic and other organic acids than the asphalt. stocks themselves. Also the combination of the heavy metal oxide and the naphthenic acid, and the settling of the litharge or other heavy metal oxide is much quicker with extract alone than with the asphalt flux or the asphalt stock itself.

A variation of this method consists in rerunning the extract in the presence of litharge or other metal oxide by distilling of! the light ends and retainingin the residue the lead naphthenates that are formed, which residue is then used for fluxing with asphalt. V

The cutbacks obtained irom the fluxes prepared by this method are about as active regarding their adhesivity to mineral aggregates as those obtained by the addition of 1% of lead oleate.

To obtain satisfactory results in the above, it is necessary that either the straight reduced asphalt or the extract used for fluxing contain enough naphthenic acids or other high molecular-weight organic acids. When neither the bitumen nor the extract contains natural naphthenic acids,

such as those obtained from Iraq crudes, 0.5 to a or more or organic high molecular weight acid, for example, oleic or naphthenic acids, is added and the asphalt or extract is then heated with the necessary amount of litharge or other metal oxide as described above. The source of naphthenic acids to be used for this purpose may be the gasoline and kerosene fractions obtained by distillation from certain crudes, such as Colomwith sodium hydroxide or sodium carbonate, yield alkali naphthenates from which the naphthenic acids are easily liberated by means of sulphuric or other strong inorganic acids. The naphthenic acids thus obtained may be added to the asphalt, the asphalt flux, the cutback or the extract in order to supply the necessary amount of high molecular weight organic acid to then combine with the heavy metal oxide to obtain adhesive bituminous binders.

Instead of adding high molecular weight organic acids to the various asphalt products, before the treatment with lead or other metal oxide,

In the briqueting soaking test containing bituminous composition with 2 of lead naphthenate, the briquet was kept under water for 390 days before final failure resulted.

It was found that the improvement in adhesivity obtained by the use of the various agents indicates that practically the same improvement is obtained with asphalts from Mexican (Panuco) Venezuelan, Mid-Continent. Colombian or cracking coal tar sources when treated with 256% by weight of lead oleate or the lead salt of the fatty acids obtained on oxidizing paraflln wax.

The following table illustrates the effect of the addition of 2 /2% of the lead soaps on different types of asphalt:

Tsau: 2

Lead salts of Adhesivity test employed None sag Lead oleate "23 5 wax Dis- Boll- Dis- 1300- Dis Boil- Dis- Boil- Souroe Grade placeing placeing placein placein! ment 1 min ment 1 min. ment 1 in ment 1 min.

10M) /5 70/80 00 80/00 00/100 95 /10 0/5 70 70/80 00 80+ 80/90 80M 5 5 80/90 60/70 80/90 80/90 iD/l00 90 /20 0/5 90 70/80 MM 81/90 00 00 5/10 5 90 70/80 00/100 70/80 fll/DO 90 10 0/5 90/100 70 80 80/90 K) H- 10 0/5 60 40/50 70 70/80 some 05 5/10 0/5 50/60 BOIW i!) 80/90 ill Do 5 5/10 70/80 70/80 70/80 90 W/lill -80 Mld-Continent Binder 0 20 0/5 80 50/60 70/80 50 80/90 80 Do 31/40 penetra /20 0/5 90 60/70 80/90 80 90/10) 90 Cracking coal tar... Ennjay 110 (100/110 pen.).. 10/20 80/90 70/80 80 90/100 80 such acids may be prepared in the bituminous product in situ by means of oxidation. Although it is possible to first oxidize the bituminous product and then treat it with the heavy metal oxide, it is preferable to carry out the oxidation in the presence of the heavy metal oxide in order to obtain good adhesive products. The oxidation -may be eii'ected by blowing the product, such as asphalt, the extract or the flux, with air or a free Tan: 1

Eflect of per cent of agent on asphalt adhesivity Adhesivity measurement Agent Agent in asphalt based on Boiling test asphalt Displacement test 1 min. 5 min.

Lead salts of fatty acids from oxidised petal. Per cent Where a Venezuelan asphalt containing fil of lead naphthenate was used to coat mineral aggregate and molded to form a briquet and immersed in water, there was no initial failure in 390 days. The boiling test by keeping an asphalt coated aggregate in water for one minute showed that 80% of the bituminous composition was not displaced from the mineral aggregate when lead naphthenate was used.

These bituminous compositions can also be used in emulsion form, that is, emulsified with water. It has been found that the spreading and adhesivity of this bituminous composition containing metallic salts of organic acids was superior to that of the same bitumen without the added salts in solution.

Other heavy metal salts of organic acids may likewise be added to the bitumen, such as 1 to 20% of heavy metal or alkaline earth metal phenolate or cresolate. The following metals come especially into consideration: Fe, Al, Mn, Zn, Co, Ni, Sn, Ca, Str, 3a,. and Mg. Various phenolic compounds may be used, such as phenol, cresols, or industrial products containing phenolic compounds, such as coal tar, coal tar pitch, lignite tar, peat tar, wood tar and shale tar. Not only the various tars mentioned but also fractions obtained by distillation thereof and containing substantial amounts of phenolic compounds are appropriate raw materials for preparing the heavy metal compounds which will improve the adhesivity of bitumens.

The heavy metal phenolates or cresolates can be obtained either by double decomposition of water soluble alkali phenolates or cresolates and a heavy metal water soluble salt, or by direct combination of phenols or cresols or of industrial products containing phenolic compounds with the heavy metal oxides, hydroxides, carbonates, etc. The phenolic compounds or the industrial products containing the same may be incorporated in' the bituminous binder and the product thus obtained heated with heavy metal oxide or hydroxide or else the heavy metal oxide or hydroxide may first be combined with the phenolic compound or the industrial product containing the same and the product thus obtained which contains heavy metal phenolates or cresolates may then be admixed with the bituminous binder. By heating coal tars with a sufficient amount of heavy metal oxide or hydroxide, especially with litharge, a highly adhesive product is obtained which, when added to bitumen or cutback in amounts of say 2 to 20%, greatly increases. their adhesivity; when the tar containing the bitumen is fractionated, and the fractions so obtained are reacted by heating with a heavy metal oxide, such as litharge, it is experienced that certain fractions give better adhesivity-improving products than others, the former indicating a predominance of phenols and cresols. The treatment of commercial tricresol by heating with litharge will give a very effective adhesivity-improving agent. a

In the preparation of the heavy metal phenolic compounds, it is often advantageous to dilute the raw material with the solvent employed in the preparation of the cutback before the heating with litharge or other heavy metal oxide. Such dilution leads to better adhesivity-improving agents. The following experiments will substantiate this statement:

, 20 parts by weight of tricresol were heated wit 20 parts by weight of PhD (about the theoretical quantity) at 110 C. for one hour, whereby a solid mass was formed which only slightly improved the adhesivity of bitumen to which it is added. This product will be called (a). In a parallel experiment parts by weight of tricresol were dissolved in 100 par-ts by weight of solvent employed. in preparing cutbacks and heated with 20 parts of PbO for one hour at 140 C. The product thereby obtained greatly improved the adhesivity of bitumen to which it was added. This product will be called (b).

These two products were then admixed with bitumen and submitted to coating tests in which the mineral aggregate to be coated was under water. Three tests were carried out:

1. No coating was obtained with the following composition: r

Parts by weight Asphalt of 85 to 100 penetration 60 Solvent for cutback 40 Product (a) 1 2. Total coating was obtained with the following composition:

, Parts by weight Asphalt of 85 to 100, penetrationl 60 Solvent for cutback 40 Product (b) 1 3. Total coating was also obtained with the following composition:

' Parts by weight Asphalt of 85 to 100 penetration 60 Solvent for cutback 16 Product (b) 4 Various coal tars were heated for one hour.

While cutbacks containing a comparatively low percentage, such as 1 to 2% and up to 5%, of heavy metal phenolic compound show good adhesivity to mineral aggregates, it is in most cases advantageous to prepare a cutback containing a high percentage, such as 5 to 20% and preferably between 10 and 15%, of heavy metal phenolic compound and use the activated cutback so obtained for precoating the mineral aggregate, after which a further amount of ordinary cutback is added or an ordinary bituminous emulsion, the added cutback or emulsion containing no ad'- hesivity-improving agent. While the process oi. improving the adhesivity of bituminous compositions has been described above in connection with the coating of mineral aggregates, it will be understood that the bituminous compositions containing heavy metal phenolic compounds willalso improve the adhesivity to metals, such as iron pipes and solid surfaces, other than mineral aggregates or metals. l I

Bituminous binders containing 0.5 to 2% of heavy metal salts of organic acids and in some cases 5 to 20% of heavy salts of organic acids have been found to have greater adhesivity to mineral aggregates and metals, such as iron pipes,

and other solid surfaces. The heavy metal soaps which are used are those soluble in oil and insoluble in water. Soaps of the following were found to be effective; lead, iron, zinc, copper, cobalt, manganese, calcium, barium, etc. acids which were used in the preparation of the said soaps are (a) fatty acids, especially those of the unsaturated series having 7 or more carbon atoms, such as oleic, linoleic, ricinoleic, etc.; (b) aromatic and naphthenic acids; (0) sulfonic acids, such as sulfolinolic acids, sulfonaphthenic acids, sulfonic acids obtained in the treatment of petroleum products, etc. Lead and iron oleates I and naphthenates were preferred.

The invention is not to be limited to the specific embodiments shown or the specific examples given, nor to any theories advanced as to the operation of the invention, but in the appended claims it is intended to claim all inherent novelty in the invention as broadly as the prior art permits.

I claim:

'1. A method of improving the adhesivity of bituminous compositions which comprises adding to a flux oil. a phenolic compound and a metal compound, subjecting the mixture of flux oil. phenolic compound and metal compound to an elevated temperature to form, a phenolicsalt of the said metal and incorporating this mixture in an asphalt.

2. A method of improving the adhesivity of bituminous compositions according to claim 1 in which the temperature to which the flux oil, phenolic compound and metal compound were subjected was C.

3. A method of improving the adhesivity of The organic bituminous compositions which comprises adding to a flux oil, a cresol and a metal compound, sub- Jecting the mixture or flux oil, cresol and metal compound to an elevated temperature to form a. cresol salt of the metal compound and thereafter incorporating this mixture in an asphalt.

4. A method of improving the adhesivity of bituminous compositions which comprises adding to a flux oil, tricresol and lead oxide, subjecting the mixture of flux oil, tricresol and lead oxide to an elevated temperature to form a tricresol salt of the lead and incorporating this mixture in an asphalt.

LUCIEN