GB1584504A - Bituminous emulsions - Google Patents

Description

(54) BITUMINOUS EMULSIONS (71) We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V., a Company organised under the laws of the Netherlands, of 30 Carel van Bylandtlaan, The Hague. The Netherlands, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention is concerned with the preparation of aqueous emulsions of chemically coupled bituminous products, with the emulsions so prepared and with the dry chemically coupled bituminous products obtained from such emulsions.

It is known to prepare chemically coupled bituminous products by reacting a bitumen having attached thereto carboxylic acid anhydride groups (hereinafter referred to as modified bitumen), optionally in admixture with a polymer also having attached thereto such groups (hereinafter referred to as modified copolymer), with coupling agents such as metal compounds, e.g. alkali-metal hydroxides, or organic compounds, e.g. polyhydroxy-, polyepoxy- or polyamino-compounds; for example, see published Netherlands Patent Application No. 7503612. Such chemically coupled bituminous products have a higher resistance against flow at higher temperatures than the uncoupled bitumens from which they are derived which is a desirable characteristic for many applications.

For some applications of bitumens it is desirable to use the bitumen in the form of an aqueous emulsion and it has also been proposed, in the above-mentioned Application, to prepare anionic aqueous emulsions of chemically coupled bituminous products by the in situ chemical coupling of a mixture of modified bitumen and modified copolymer by reaction thereof with an aqueous solution of a metal compound coupling agent and an emulsifier which may be the metal compound coupling agent itself. Although aqueous emulsions of chemically coupled bituminous product may be prepared in this manner it has been found that the dried chemically coupled bituminous products, obtained from such emulsions, do not retain their resistance to flow at high temperatures.

The Applicants have now found that aqueous emulsions of chemically coupled products may also be prepared by mixing the modified bitumen, optionally in admixture with a modified polymer, with an aqueous solution of a polyamine having at least two non-tertiary amino groups and an emulsifier. Moreover, the dried chemically coupled bituminous product obtained from these emulsions are more resistant to flow at high temperatures than the dried chemically coupled bituminous products obtained from emulsions of the type described in the above-mentioned Application.

According to the present invention, a process for preparing an aqueous emulsion of a chemically coupled bituminous product comprises mixing a bitumen having attached thereto carboxylic acid anhydride groups, optionally in admixture with a polymer also having attached thereto such groups, with an aqueous solution of a polyamine having at least two non-tertiary amino groups and an emulsifier.

The modified bitumen for use in the present invention may be prepared by reacting a bitumen with an olefinically unsaturated anhydride, e.g. maleic anhydride, by the so-called "maleinization" reaction. The maleinization may be carried out by well-known methods, for example by heating the bitumen with maleic anhydride at a temperature in the range of from 100 to 200"C with stirring. The amount of maleic anhydride is suitably from 0.5 to 10 %w, based on weight of bitumen. Thus only a minor part of the bitumen may be maleinized. The proportion of anhydride groups in the modified bitumen, or in the mixture thereof with modified copolymer may vary between wide limits but preferably corresponds to an acid value, determined by titration of from 0.01 to 2.0 meq/g. more preferably of from 0.1 to 0.35 meq/g.The modified bitumen may be blended with solvents or diluents ("cutbacks") before being used to prepare the emulsions.

The bitumen which is used to prepare the modified bitumen may be a naturally occurring material, such as gilsonite, but is preferably derived from mineral oil. As examples of suitable bitumens may be mentioned: distillation or "straight-run" bitumens; precipitation bitumens e.g. propane bitumens; blown bitumens e.g. those obtained by the air-blowing of straight-run bitumens; and cracked bitumens which are obtained as residues from a cracking operation, for example pitches formed as by-product of the thermal cracking at atmospheric pressure of suitable distillation residues. Blends of these bitumens with each other and/or with solvents or diluents may also be considered.

As stated above the modified bitumen may be used in admixture with a modified polymer which may also be prepared by reacting a polymer with an olefinically unsaturated anhydride, e.g. from 0.5 to 10%w, as described above for the preparation of the modified bitumen. If a mixture of a modified bitumen and a modified polymer is used, it may be prepared by mixing together the separately prepared components or by reacting a mixture of the bitumen and polymer with the olefinically unsaturated anhydride. Suitable reaction temperatures are from 100 to 200C C. The amount of anhydride used is suitably from 0.5 to 10 %based on weight of bitumen and polymer.The amount of modified copolymer which may be present in such mixtures may vary between wide limits with mixtures in which the modified bitumen represents the major amount, e.g. more than 80 % w of the mixture, are preferred. Particularly preferred amounts of the modified copolymer are from 0.1 to 10 %w, based on the weight of the mixture. The mixture may be blended with solvents or diluents before being used to prepare the emulsions.

The polymers which are used to prepare the modified polymers are suitably olefinically unsaturated elastomeric material having preferred molecular weights in the range 100,000 to 500,000. Particularly suitable are rubbers such as natural or synthetic rubber or a rubber-like polymer or copolymer. The polymers may be linear, branched or star-shaped. Particularly suitable polymers are natural rubber, styrene-butadiene rubber, styrene-butadiene-styrene rubber, isoprene rubber, butadiene rubber, nitrile rubber, polyurethane rubber,chlor'oprene rubber and ethene-propene rubber. Preferred polymers are styrene-butadiene rubbers, especially those comprising styrene and butadiene in molar ratios of from about 1:3 to 1:6 and having molecular weights in the range of from 100,000 to 500,000 e.g. "CARIFLEX" S 1712 and "CARIFLEX" S 1500 ("CARIFLEX" is a registered Trade Mark).

As stated above the modified bitumen, and optionally the modified polymer, is mixed with an aqueous solution of the polyamine and an emulsifier. Preferably the amount of modified bitumen and modified polymer, if any, added to the aqueous solution is from 50 to 125 %w based on the weight of the water in the aqueous solution.

Suitable polyamines present in the aqueous solution are those having at least two primary amino groups. Preferred polyamines are aliphatic polyamines having at least two primary amino groups. Examples include the mono- and polyalkylene polyamines, such as ethylene diamine, propylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine etc. The polyamines may have groups other than amino groups, for example mercapto or hydroxyl groups. Particularly suitable polyamines are the polyalkylene polyamines which are usually prepared by reacting ethylene dichloride with ammonia. Preferred polyalkylene polyamines may be represented by the general formula: H2Nt alkylene- NH)nH wherein n is an integer having an average value of at least 3, more preferably of at least 5.

Such preferred polyalkylene polyamines may be obtained as the residue in the above reaction after removal of the ethylene diamine and lower polyalkylene polyamines. Such residues are mixtures of compounds including nitrogen compounds other than polyamines. The amount of polyamine present in the aqueous solution may vary between wide limits but is usually from 25 to 500 %w of that required to react stoichiometrically with the carboxylic acid anhydride groups of the modified bitumen and modified polymer, if any. Amounts ranging from 50 to 300 %w, particularly from 75 to 200 %w of the theoretical amount, are preferred, however.

The aqueous solution should be free of components e.g. inorganic acids such as hydroch loric acid which would react with the polyamines and thereby prevent the reaction of the amines with modified bitumen and modified polymer if any.

Suitable emulsifiers for use in the present invention are of the anionic, non-ionic or amphoteric type. Examples of anionic emulsifiers include metal salts, such as the alkali metal salts of weak acids and of alkylbenzene sulphonic acids, e.g. the sodium and potassium salts of oleic and lauric acids. Examples of non-ionic emulsifiers include alkylene oxide e.g. ethylene oxide adducts of fatty alcohols e.g. Cs to C20 alcohols and of alkyl phenols, e.g. C6 to C20 alkyl phenols. Examples of amphoteric emulsifiers include sulphobetaines and betaines. Preferred emulsifiers are anionic or non-ionic emulsifiers. The amount of emulsifier present in the aqueous solution may vary between wide limits but is suitably from 0.1 to 5.0 %w based on the weight of modified bitumen and modified polymer, if any.

The aqueous solutions used in the process of the present invention may, if desired, contain other ingredients such a semulsion stabilizers e.g. bases e.g. alkali-metal hydroxides, which stabilize the aqueous emulsions, especially non-ionic emulsions, of the chemically coupled bituminous product.

The aqueous emulsions are prepared by conventional techniques such as by adding the modified bitumen, and modified polymer, if any, in a liquid or molten state to the aqueous solution. Suitably the temperature of the aqueous solution is from ambient temperature to 50"C. The mixture is suitably agitated. Equipment e.g. a Hurrell mill, conventionally used for preparing bituminous emulsions may be used.

The aqueous emulsions prepared by the process of the present invention may be used in a wide variety of applications such as coatings e.g. car body undercoatings, adhesives, waterproofing, roofing and road coverings etc. The aqueous emulsions may be applied to the article to be coated by conventional techniques such as brushing or spraying. The emulsion is then allowed to dry.

The invention will now be illustrated by reference to the following Examples. In the examples the penetration refers to the penetration (0.1 mm) at 250C according to ASTM D5 and the softening point to the Ring and Ball softening point ("C) according to ASTM D36.

Examples I and 2 A mixture of modified bitumen and modified polymer was prepared as followed. 120 g of of a styrene-butadiene rubber, MW 200,000, bound styrene 23 %w ("CARIFLEX" S 1500) was dissolved in 3000 g of a Kuwait short residue bitumen (penetration 300) by sitrring with a Silverson high shear mixture at 1600C. The solution was then reacted with 60 g of maleic anhydride for 3 hours at 1800C. The final product was admixed with 5 %w of kerosene.An aqueous emulsion of a chemically coupled bitumen/polymer mixture was then prepared (Example 1) by mixing, with a Hurrell mill, 300 g of the mixture prepared as above, having a temperature of 1500C with 200 g of an aqueous solution containing 1.2 g of a polyalkylene polyamine having an average molecular weight of from 250 to 300 E 100 exDow), 3.0gofa non-ionic emulsifier (Antarox CO 990, a registered Trade Mark and 1.0 g of potassium hydroxide.

A further aqueous emulsion of a chemically coupled bitumen/polymer mixture was prepared (Example 2) by mixing, with a Hurrell mill, 1500 g of the mixture prepared as above, having a temperature of 1500C, with 1000 g of an aqueous solution containing 4 g of the polyalkylene polyamine described above (E 100 ex Dow) and 18 g of potassium oleate (an anionic emulsifier).

Steel plates were then coated with a layer (1.6 mm thick) of the emulsion and the emulsion allowed to dry after which the plates were placed vertically in an oven, at various temperatures, for 2 hours and the flow of the dried chemically coupled bituminous product determined. The results are given in Table I.

For comparison an aqueous emulsion (Example a) was prepared as described above but with the difference that the aqueous solution did not contain the polyamine coupling agent.

Also for comparison an aqueous emulsion (Example b) was prepared by mixing, with a Hurrell mill, 500 g of the mixture prepared as above, having a temperature of 1500C with 500 g of an aqueous solution containing 5 g of potassium hydroxide and 7.5 g of a non-ionic emulsifier (Antarox CO 990, a registered Trade Mark). Also for comparison an aqueous emulsion (Example c) was prepared by mixing, with a Hurrell mill, 600 g of the mixture prepared as above, having a temperature of 1500C with 400 g of an aqueous solution containing 3.1 g of potassium hydroxide and 5.4 g of potassium oleate (an anionic emulsifier).

The aqueous emulsions were tested as above and the results are also given in Table I.

Table I Example Flow (mm) 80"C 100 C 1200C 140"C 1 0 0 0 2-8 2 0 0 6 > 20 a > 20 - - b 0 > 20 - c - > 20 - Example 3 The procedure of Example 1 was repeated using an emulsion prepared from 300 g of a modified bitumen alone and 200 g of an aqueous solution containing 3 g of the non-ionic emulsifier, 4 g of the polyamine coupling agent and 1 g of potassium hydroxide.

The modified bitumen was prepared by reacting 1000g of a Kuwait semi-blown bitumen (ASTM penetration 80-100) with 40 g of maleic anhydride. The product was admixed with 15 %w of an aromatic oil extract (Dutrex 729 HP).

The emulsion was dried and the dried chemically coupled bituminous product was found to have a softening point of 73"C. A dried bituminous product obtained from an aqueous emulsion prepared as described above, with the difference that the aqueous phase did not contain the polyamine coupling agent, was found to have a softening point of 45"C.

WHAT WE CLAIM IS: 1. A process for preparing an aqueous emulsion of a chemically coupled bituminous product comprises mixing a bitumen having attached thereto carboxylic acid anhydride groups, optionally in admixture with a polymer also having attached thereto such groups, with an aqueous solution of a polyamine having at least two non-tertiary amino groups and an emulsifier.

2. A process as claimed in claim 1, wherein the bitumen is the reaction product of a bitumen with maleic anhydride and the polymer, if present, is the reaction product of an olefinically unsaturated polymer with maleic anhydride.

3. A process as claimed in claim 2, wherein the polymer, if present, is the reaction product of a styrene-butadiene rubber with maleic anhydride.

4. A process as claimed in any one of claim 1 to 3, wherein the amount of the bitumen having attached thereto carboxylic acid anhydride groups together with the amount if any, of the polymer also having attached thereto such groups is from 50 to 125 %w based on the weight of the water in the aqueous solution.

5. A process as claimed in any one of claims 1 to 4, wherein the polyamine is a polyalkylene polyamine, preferably a general formula: H2Nt alkylene -NH+nH wherein n is an integer having an average value of at least 3.

6. A process as claimed in any one of claims 1 to 5, wherein the amount of polyamine is from 25 to 500 %w of the amount required to react stoichiometrically with the carboxylic acid anhydride groups of the bitumen, and, if present, polymer.

7. A process as claimed in any one of claims 1 to 6, wherein the emulsifier is an anionic or a non-ionic emulsifier.

8. A process as claimed in any one of claims 1 to 7, wherein the amount of emulsifier is from 0.1 to 5.0 %w based on the amount of the bitumen having attached thereto carboxylic acid anhydride groups together with the amount, if any, of the polymer also having attached thereto such groups.

9. A process for preparing an aqueous emulsion of a chemically coupled bituminous product as claimed in claim 1, substantially as hereinbefore described with particular reference to the Examples.

10. An aqueous emulsion of a chemically coupled bituminous product whenever prepared by a process claimed in any one of claims 1 to 9.

11. Dried chemically coupled bituminous products whenever obtained from an aqueous emulsion of a chemically coupled bituminous product as claimed in claim 10.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. modified bitumen alone and 200 g of an aqueous solution containing 3 g of the non-ionic emulsifier, 4 g of the polyamine coupling agent and 1 g of potassium hydroxide. The modified bitumen was prepared by reacting 1000g of a Kuwait semi-blown bitumen (ASTM penetration 80-100) with 40 g of maleic anhydride. The product was admixed with 15 %w of an aromatic oil extract (Dutrex 729 HP). The emulsion was dried and the dried chemically coupled bituminous product was found to have a softening point of 73"C. A dried bituminous product obtained from an aqueous emulsion prepared as described above, with the difference that the aqueous phase did not contain the polyamine coupling agent, was found to have a softening point of 45"C. WHAT WE CLAIM IS:

1. A process for preparing an aqueous emulsion of a chemically coupled bituminous product comprises mixing a bitumen having attached thereto carboxylic acid anhydride groups, optionally in admixture with a polymer also having attached thereto such groups, with an aqueous solution of a polyamine having at least two non-tertiary amino groups and an emulsifier.

2. A process as claimed in claim 1, wherein the bitumen is the reaction product of a bitumen with maleic anhydride and the polymer, if present, is the reaction product of an olefinically unsaturated polymer with maleic anhydride.

3. A process as claimed in claim 2, wherein the polymer, if present, is the reaction product of a styrene-butadiene rubber with maleic anhydride.

4. A process as claimed in any one of claim 1 to 3, wherein the amount of the bitumen having attached thereto carboxylic acid anhydride groups together with the amount if any, of the polymer also having attached thereto such groups is from 50 to 125 %w based on the weight of the water in the aqueous solution.

5. A process as claimed in any one of claims 1 to 4, wherein the polyamine is a polyalkylene polyamine, preferably a general formula: H2Nt alkylene -NH+nH wherein n is an integer having an average value of at least 3.

6. A process as claimed in any one of claims 1 to 5, wherein the amount of polyamine is from 25 to 500 %w of the amount required to react stoichiometrically with the carboxylic acid anhydride groups of the bitumen, and, if present, polymer.

7. A process as claimed in any one of claims 1 to 6, wherein the emulsifier is an anionic or a non-ionic emulsifier.

8. A process as claimed in any one of claims 1 to 7, wherein the amount of emulsifier is from 0.1 to 5.0 %w based on the amount of the bitumen having attached thereto carboxylic acid anhydride groups together with the amount, if any, of the polymer also having attached thereto such groups.

9. A process for preparing an aqueous emulsion of a chemically coupled bituminous product as claimed in claim 1, substantially as hereinbefore described with particular reference to the Examples.

10. An aqueous emulsion of a chemically coupled bituminous product whenever prepared by a process claimed in any one of claims 1 to 9.

11. Dried chemically coupled bituminous products whenever obtained from an aqueous emulsion of a chemically coupled bituminous product as claimed in claim 10.