NO773199L - IMPROVED BITUMEN MIXTURE. - Google Patents

Description

Improved bitumen mixture.

The present invention relates to new bitumen mixtures in which

a high molecular weight olefinic unsaturated organic compound is added to bitumen.

When bitumen is used for various purposes, for example as a binder for coatings or for road covering purposes, they must exhibit certain necessary mechanical properties. These properties are determined by various tests, of which the following can be mentioned: - test for determining the softening point (the so-called "Ring and Ball" test) according to French standard NF T 66-008,

- test for determination of Fraass or breaking point in accordance

to standard IP 80/53,

- test for the determination of stickiness, in which the adhesiveness of the bitumen is determined in the presence of water according to the method described by the French Laboratoire Central des Ponts et Chaussées (test for the determination, in the presence of water, of a binding

film of bituminous, fluidized bituminous, fluxed bituminous, tars, composite tars, June 1971), - test for determination of fracture rheological properties, i.e. ultimate breaking strength (bar), ultimate elongation (%), breaking strength (bar) and breaking elongation (%) according to to French standard NF T 66 004,

I - test for determining penetration (penetration value) according to French standard NF T 46 002. i

Conventional bitumen does not generally meet all these requirements, and it has already been proposed to add certain products, especially polymers, to the bitumen in order to improve the mechanical properties of the bitumen. The added polymers or copolymers, which are often referred to as elastomers, are components with a high molecular weight, preferably higher than 100,000.

These elastomers will improve the mechanical properties of the bitumen, but in most cases they result in solubility problems which result in separation problems during storage.

It is an aim of the present invention to overcome these disadvantages by providing a method which, instead of only mixing the added polymer, adds an olefinically unsaturated organic compound with a relatively high molecular weight, even if this molecular weight is significantly less than the above-mentioned polymers, by chemical reaction to reactive sites in bitumen.

It is also a purpose of the present invention to provide new bitumen mixtures which are obtained by contacting, at a temperature in the range 140 - 220°C:

- a bitumen with a penetration value in the range 30 - 220 med

an olefinically unsaturated organic compound with the general formula:

in which the groups , R_ and R^ are either hydrogen or methyl,

of which at least two of these groups are a methyl group, and wherein R is essentially a hydrocarbon group which may be saturated or unsaturated and which may include cyclic groups and functional groups such as a carboxyl group, and where this

group is chosen so that the molecular weight of the organic compound

In these lies in the area 300 - 3000,

in

- in the presence of sulphur.

IN

The olefinically unsaturated organic compound is generally added

in the form of a liquid and in such a quantity that it constitutes 5-30% by weight of the amount of bitumen.

The amount of sulfur added during the preparation of the mixture

is chosen so that sulfur makes up 0.2-4% by weight of the total amount of the other two components.

Any synthetic bituminous and asphalts, if applicable

blown with air or steam, can be used to produce the mixtures according to the present invention. The penetration value is chosen essentially taking into account the particular application for the prepared mixture. The penetration or penetration value is measured according to the method

that specified in the American Standard ASTM D 5 52 which corresponds to the French standard NFT 66004.

The organic compound corresponding to the formula shown above exhibits two essential properties, namely: - a double bond at the end of the chain, either in the a- or ..position, where one of the two carbon atoms connected to the double bond is connected to at least one methyl group, the organic compound may also comprise a second double bond at the other end of the chain, and - the molecular weight is in the range 300 - 3000, preferably in the range 400 - 2000.

The above-mentioned organic compound may be a polymer

or a copolymer with a relatively low molecular weight (oligomers).

In this case, the group R indicated in the above general formula is a linear or optionally branched group, when the polymer consists of polyisobutene or polybutadiene. It can

also contain cyclic groups when the polymer consists of piperylene-isoprene and cyclopentadiene-isoprene, as in the case of petroleum resins containing 5 carbon atoms, with

In tylstyrene and vinyltoluene such as petroleum resins containing!<I>

9 carbon atoms. in

The olefinically unsaturated organic compound may also contain a non-polymeric large molecule, in which the group R, in the general formula, is constituted by linear or cyclic structures which may contain functional groups, especially carboxyl groups. Among structures of this type can be mentioned esters of fatty acids (oleic acid, palmitic acid, stearic acid, etc.), and higher alcohols such as lanosterol, cholesterol, isocholesterol, etc. Such structures are found especially in lanolin.

These structures can be schematically represented by the general formula:

where n is 12 - 16.

It will be understood that the olefinically unsaturated organic compound used for the preparation of the mixture according to the present invention often consists of a mixture of a number of closely related compounds.

Thus in this case the molecular weight will be the average molecular weight for the mixture.

When the mixture of bitumen and the olefinically unsaturated compound is prepared, sulfur incorporated into the mixture will act as a "catalyst" with regard to the addition of the organic compound to the bitumen. Sulfur will not remain in the reaction medium, but will be released during the reaction in the form of hydrogen sulphide. The reaction mechanism for sulfur is probably of a radical nature, and it is therefore important to incorporate sulfur into j

II an active form, taking into account the assumed type of reaction, especially in the form of flower of sulphur, powdered sulphur, molten sulphur, etc., i.e. generally a form in which sulfur is not chemically bound.

Preferably, the reaction is carried out at a temperature at which . the various components in the mixture are in liquid form, i.e. a temperature in the range 140 - 220°C, preferably in the range 160 - 210°C.

The reaction time, i.e. the time during which contact between the different components of the mixture is critical, is to achieve a satisfactory addition of the organic compound to the bitumen used.

This reaction time should be at least 10 h, and there is no theoretical upper limit, but practice has shown that the reaction time should not be longer than 20 h.

Preferably, the reaction time is carried out in the presence of an inert gas such as nitrogen or argon. This inert gas can, for example, be bubbled through the molten mass which is subjected to stirring, •

The invention will now be described with reference to the following examples.

Example 1

13.4 parts of liquid polyisobutene with an average molecular weight of 1015 and 3.7 parts of sulfur are added to 100 parts of "Safanyah 80 - 100" bitumen. The mixture is heated to 166°C

in an inert atmosphere, with stirring, for approx. 13 hours. A chemical reaction takes place in the mixture and hydrogen sulphide is released.

The properties of the modified bitumen (B) thus obtained, as well as the properties of the starting bitumen (A) are

given in the following table I.

Example 2

The same method as described in example 1 is used, except that instead of polyisobutene, 13.4 parts of "normal fat" obtained from a neutral extract of sheep's wool are used,

and which has the following properties:

- average molecular weight: 680.

- moisture content (H20)<1%, determined by drying at 105°C

for 4 hours,

- acid number: 4-6, the acid number indicates the number of mg of KOH required

to neutralize the free acid present in the fat.

- saponification number: 90 100%o, (90 - 100^),

- ash: 0.1- 0.3%o,

- cholesterol: 10 - 13%, determined chromatographically in the sterols contained in the non-saponifiable material.

This normal fat is a mixture of esters formed by fat-

acids and higher alcohols, as previously described.

The mechanical properties of the thus modified bitumen (C) are given in table I.

Example 3 I!

In this comparative example, the method described in example 1 was used, however, no polyisobutene was incorporated into the reaction medium. The properties of the obtained bitumen (D) are given in Table I.

Example 4

In this comparison example, the procedure was according to

to Example 1 repeated, but the reaction medium was heated to 166°C for 15 min. instead for 13 h. The properties of the thus obtained product (E) are given in table I.

Example 5

In this comparison example, the procedure was according to

to Example 1 followed, however, no sulfur was incorporated. The properties of the obtained product (F) are given in table 1.

The properties indicated in table 1 are determined according to the previously mentioned standard test methods.

Analysis of the obtained products indicated in table 1 shows that:

- the olefinically unsaturated organic compound added to

bitumen significantly improves all the mechanical properties of the starting bitumen (compare bitumin B and C

with bitumen A),

- when the organic compound is absent (bitumen D)

the properties at low temperature (break point) are significantly less satisfactory. - In addition, an insufficient reaction time (bitumen E) will result in a significant lowering of the softening point and ultimate breaking strength.

i - The results given in Table 1 also show that when sulfur does not

: is present in the reaction medium, the organic compound j

as such act only as a solvent for bitumen ' !

without improving their properties.

Examples 6-11 •

In these examples, different parameters for the method were used

according to the invention for the production of the bitumen mixtures varied, i.e. the sulfur content in the mixture, the amount of added olefinic unsaturated organic compound (oligomers), the molecular weight of the polymer and the reaction temperature, as well as the reaction time.

The conditions used when carrying out these tests and the main properties of the bitumen obtained are shown in tables 2 and 3, the treated bitumen or the starting bitumen is the same as described in example 1.

The results shown in tables 2 and 3 show that the conditions for carrying out the present method can be varied within the limits described above, and that the products obtained are very similar when compared with each other with respect to the plasticity interval Det. It should also be noted, as can be seen from example 6, that if the molecular weight of the polymer is too low, the end product will be of poor quality and even less satisfactory than the bitumen used as starting material.

Claims (6)

1. New bitumen mixtures characterized in that at 140 - 220°C a. bitumen with a penetrance value in the range 30 - 220, no chemically bound sulfur and an olefinically unsaturated organic compound with the general formula: in which the groups , R^ and R^ are either hydrogen or methyl, with j| at least two of these groups e: e: methyl group, and where R is a group i, essentially of a hydrocarbon nature and possibly comprising. , <!> i I 'cyclic groups and functional groups, such as a carboxyl- I . group, and where the group has a molecular weight such that the molecular weight of the organic compound is in the range 300 - 3000. 2.B landings according to claim 1, characterized in that the amount of olefinic unsaturated organic compound constitutes 5-30% by weight of the amount of bitumen, and that the amount of added sulfur amounts to 0.2-4% by weight of the amount of the other two components in the mixture. 3. Mixtures according to claim 1 or 2, characterized in that the olefinically unsaturated compound is an olefinic polymer with an average molecular weight in the range 400 - 2000. '4. Mixtures according to claim 1 or 2, characterized in that the olefinically unsaturated compound is a mixture of esters of fatty acids containing 14 - 13 carbon atoms and higher alcohols. 5. Mixtures according to claims 1-4, characterized in that the components of the mixture are contained in contact with each other for at least 10 h. 6. Mixtures according to claims 1-5, characterized in that the components of the mixture are mixed in the presence of an inert gas.