DK157032B - PROCEDURE FOR PREPARING A WATER-BITUMEN-containing EMULSION - Google Patents

Description

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DK 157032 B

The present invention relates to a process of the kind set forth in the preamble to the claim for preparing an aqueous bitumen-containing emulsion.

It is known to use bitumen-containing compositions 5 containing a bituminous component and a rubber or rubbery block copolymer for a variety of applications, such as in road construction, as adhesives for synthetic roofing materials and as pressure-sensitive adhesives.

So far, only the relatively high viscosity of such 10 mixtures, especially in the case of high bitumen content, has been reduced by the addition of volatile organic solvents, see, for example, British Pat.

1201135.

The use of such a "diluted" bitumen, a so-called "cutback" product, shows in practice great disadvantages. Thus, for example, the bitumen components and the block polymer must satisfy stringent requirements to be compatible with each other.

According to British Patent Specification No. 1,201,135, only 20 certain bitumen substances and certain block copolymers can be stored in admixture with one another and additionally withstand dilution with organic solvents without entering phase separation at room temperature.

By the addition of relatively large quantities of 25 volatile solvents, road construction can be applied at room temperature up to a temperature of approx. 95 ° C. One disadvantage of this precaution, however, is that the volatile solvent must be evaporated after the application of cutback along the way, which gives rise to the presence of relatively large amounts of hydrocarbons in the atmosphere.

In addition, this evaporation is time consuming, so that no traffic on the road can be allowed for a considerable period of time because the bituminous composition must be almost solvent-free to achieve the desired hardness. Furthermore, skin formation is often observed. which delays the evaporation of the volatile solvents even more.

DK 157032 B

2 X case of bituminous preparations to be used as adhesives, it is often a disadvantage that they must be applied at elevated temperature (due to the necessary flow properties), especially if one or both of the 5 parts to be adhered to each other cannot withstand high temperatures, such as if they are made of foamed polystyrene.

German Patent Publication No. 1815026 does, however, describe aqueous bitumen emulsions that have come without these drawbacks. These are statistical mixture polymers emulsified with the bituminous aqueous phase substance. However, it has been found that stable emulsions cannot be prepared in the manner described in German Publications No. 1815026.

It has now surprisingly been found that despite high viscosity, mixtures of a bitumen component and certain block copolymers can be converted into well-workable and stable aqueous emulsions on condition that special precautions are taken.

The invention thus relates to a process for preparing an aqueous bitumen-containing emulsion containing a) a bituminous component whose aromaticity, expressed as the fraction of n-heptane malt (f) aromatic carbon, is higher than 0.004 x P + 0.280, where c1 P indicates the weight percent of n-heptane asphaltenes in the bi-tuminose component, b) a block copolymer of the general formula ABA where the two blocks A are the same or different thermoplastic non-elastomeric polymer blocks produced by polymerization of one or more monovinyl aromatic compounds and wherein B is an elastomeric polymer block prepared either by polymerization of one or more conjugated dienes or by copolymerization of one or more conjugated dienes with one or more monovinyl aromatic compounds, which polymer block B is optionally partially or completely hydrogenated, and

DK 157032 B

3 c) an emulsifier and the process according to the invention are characterized by the characterizing part of the claim, i.e. by first mixing components a) and b) and then emulsifying this mixture in water in the presence of (c) at 100 ° C. 200 ° C and at a pressure above atmospheric pressure.

The aqueous emulsions produced by the process according to the invention have the advantage over those of British Patent Specification No. 1,201,355 that cutback products are extremely environmentally friendly because no solvent vapors are released into the free atmosphere. In addition, these emulsions are well processable despite high binder content; the reason for this is that their viscosity is sufficiently low.

As bituminous components, mixtures of one or more of the aforementioned materials with aromatic petroleum extracts, aromatic petroleum distillates or paraffinic-naphthenic petroleum distillates can be suitably used in such an amount that the desired aromaticity is obtained. When using a bituminous component of this type, a mixture of a precipitate bitumen and an aromatic petroleum extract is preferably selected, in particular a mixture of a propane bitumen and an aromatic extract of a heavy lubricating oil.

25 In the block copolymer A-B-A which constitutes the one component

in the aqueous emulsion, the thermoplastic polymer blocks A preferably have a molecular weight between 7500 and 100,000, especially between 10,000 and 50,000. Preferably, the elastomeric polymer block B of block copolymer A-B-A has a molecular weight between 25,000 and 1,000,000, especially between 35,000 and 150,000. Preferably, the amount of the thermoplastic polymer blocks A in the block copolymer A-B-A

10-70 wt%, especially 20-50 wt% of the block copolymer A-B-A. As monovinyl aromatic monomers suitable for the preparation of the thermoplastic polymer blocks A and the elastomeric polymer blocks B of the block copolymer, there are mentioned styrene and α-methylstyrene. As conjugated diene which is suitable

DK 157032 B

4 as monomer to prepare the elastomeric polymer block B in the block copolymers in question, dienes having 4 to 8 carbon atoms per molecules, especially butadiene and isoprene.

Examples of suitable block copolymers are polystyrene-polyisoprene-polystyrene, polystyrene-polybutadiene-polystyrene, polystyrene-partially hydrogenated polyisoprene-polystyrene, polystyrene-almost fully hydrogenated polybutylene-diene-polystyrene, and polystyrene-styrene-butadiene copolymer. polystyrene. Preferably, a polystyrene-polybutadiene-polystyrene block copolymer is used in the aqueous emulsion prepared according to the invention.

The emulsifier may be of any type suitable as a dispersant for bituminous materials and may be, for example, an anionic emulsifier, a cationic emulsifier or a nonionic emulsifier. It may appear as a solid powder. Mixtures of emulsifiers, e.g., of cationic and nonionic emulsifiers, can also be used.

Examples of anionic emulsifiers include various kinds of soaps such as alkali metal salts of fatty acids, resin acids and naphthenic acids as well as alkaline proteins such as caseinates.

As an example of a solid powder which can advantageously be used in the preparation of the emulsion may be mentioned a colloidal 1er such as, for example, bentonite.

Examples of cationic emulsifiers include salts, for example, with hydrochloric acid or acetic acid of long alkyl chain mono- and polyamines (i.e. containing at least 30 carbon atoms), quaternary long-chain ammonium salts, and long alkyl chain pyridinium salts. Suitable as polyamines are high-grade (poly) -alkylene polyamines with long hydrocarbon chain, for example alkylated triethylenetetramine and tetraethylenepentamine. As particular examples may be mentioned the hydrochloric acid salt of N-alkyl-1,3-propylenediamine wherein the alkyl chains are derived from fatty acids and contain 16 and / or 18 carbon atoms.

DK 157032 B

5 In the salts of amines which can be used as cationic emulsifiers, the number of equivalents of acid used for salt formation does not necessarily have to be exactly equal to the number of equivalents of basic nitrogen 5 in the amine. Excess acid or amine can be used, but excess acid is usually preferred.

Whether one should prefer an emulsion prepared by an anionic or a cationic emulsifier (hereinafter referred to as anionic and cationic emulsion, respectively) depends on the intended use of the emulsion and the ambient conditions. For example, an anionic emulsion will in many cases be suitable for use in road construction. Since a cationic emulsion generally breaks somewhat more easily in contact with the mineral material (e.g., stone) used in the construction than an anionic emulsion, the former is particularly preferred where relatively low temperatures prevail, e.g., in autumn and spring. In the case that a large proportion of the stones in the road have a negative charge on the surface, for example consisting of silicates, the use of cationic emulsions is very advantageous.

The amounts of the bituminous component, the block copolymer, the emulsifier and water in the aqueous emulsions prepared according to the invention may vary within wide limits.

Very conveniently, the amount of the block copolymer is from 2-50% by weight of the total amount of block copolymer plus bituminos component. If it is intended to use the aqueous emulsion for road construction, the proportion of block copolymer is preferably 5-15% by weight of the total 30 amounts of block copolymer and bituminos component. For use as an adhesive, for impregnating paper for roofing materials, stone cladding and dykes or ditches, for coating on building elements and other industrial applications of quantities of block copolymer of 10-25% by weight of the amount of block copolymer plus bituminos component very appropriate. For putty and priming in the paint industry and paints, the amount of block copolymer is often no- »

DK 157032 B

6, up to 50% by weight of the total block copolymer plus bituminos component.

The amount of emulsifier in the aqueous emulsion may also vary within wide limits, but it will be understood that the proportion thereof is kept as low as possible to obtain an emulsion of desired stability. Large amount of emulsifier will delay breaking of the emulsion after application at the desired location. Amounts of 0.05-2% emulsifier, in particular 0.1-1%, based on the total weight of the emulsion, are generally very convenient. If a solid powder is used as an emulsifier, the proportion can often be up to 15% of the total weight of the emulsion.

The amount of water is chosen so that the aqueous emulsion has a viscosity that provides good manageability at ambient temperature and at the application temperature (e.g., the emulsion could easily be sprayed if used for road construction) while the viscosity, on the other hand, must not be so high that the emulsion flows away from the processing site, eg by road construction from the stones. Water volumes of 22-55%, especially 30-40%, based on the total weight of the emulsion, are particularly suitable for most applications.

The viscosity of the bituminose component in the emulsion is conveniently expressed by the penetration at 25 ° C, determined in accordance with ASTM method D 5.

It may vary within wide limits and be selected according to the intended use.

For several industrial applications, aqueous emulsions with a bituminous component having a penetration up to 2000 at 25 ° C may be used, while a penetration of the bituminous component of 10-300 at 25 ° C is very suitable for road building purposes.

Optionally, the emulsion may also contain fillers, antioxidants, compounds affecting the rheological properties (e.g., mineral salts, asbestos and cellulose derivatives), compounds having an effect on the rate at which the emulsion breaks (e.g., calcium chloride),

DK 157032 B

7 additives and other usual additives.

The mixing of the bituminous component a) and the block copolymer for the emulsification can be carried out in a simple manner by stirring the block copolymer in the form of a finely divided solid or in the form of a solution in the molten bituminous component.

Since a mixture of components a) and b) often has a high viscosity, the emulsification must be carried out at elevated temperature and pressure, at 100-200 ° C and at a pressure above atmospheric pressure by mixing the components intimately, e.g. and a colloid mill.

If a long-chain amine site is to be used as an emulsifier, it is often advantageous to add the amine to the emulsification of the mixture of the bituminous component a) and the block polymer b) with the acid from which the salts are derived (e.g. hydrochloric or acetic acid) in the water for the emulsification. The number of equivalents of basic nitrogen in the amine need not be exactly the same as the number of acid equivalents.

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Example

A bitumen (obtained by admixing a propane bitumen and an aromatic extract of a heavy residual lubricating oil) with a penetration of 100 (determined according to ASTM 25 method D 5), a content of the n-heptane asphalt of 7 (determined after IP method 143) and a value of 0.36 (calculated from density 20/4, the percentage of carbon and the percentage of hydrogen according to the method described by RB Williams in Proceedings, 6th World 20 Petroleum Congress, section V, paper 17, 1963) was blended with a polystyrene-polybutadiene-polystyrene block copolymer in which the polystyrene blocks had a molecular weight of 14,000 and the polybutadiene block had a molecular weight of 65,000. The proportion of block copolymer was 6% of the total weight of the mixture.

This mixture was emulsified by introducing it at a temperature of 180 ° C into a pressurized colloid mole together with an aqueous phase which, in addition to water, contained

DK 157032 B

8 0.35 wt% alkylpropylenediamine and 0.18 wt% hydrochloric acid and having a temperature of 38 ° C. The weight ratio of the mixture of the bituminous component on the one hand and the mixed aqueous phase on the other side was 68:32. A stable emulsion is obtained.

This emulsion was applied to a strong traffic. 2 straight way, spreading 1 liter of emulsion per m. Then 10 mm granite shingles were scattered. After a year, the road was in very good condition; the loss of 10 stones was small and no oil layer formed.

In comparison, an emulsion of a bitumen with a penetration of approx. 200, which contained no block copolymer, on the same path and granite shavings as described above were sprinkled. The surface coating was completely destroyed after 30 days of oil formation and loss of stone.

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Claims (1)

Process for preparing an aqueous bitumen-containing emulsion containing (a) a bituminous component whose aromaticity, expressed as the fraction of aromatic carbon of the n-heptane malt phase (f), is higher than 0.004 x P + 0.280 wherein cL P is the weight percent of n-heptane asphaltenes in the bituminous component, and (b) a block copolymer of the general formula ABA, wherein the two blocks A represent the same or different thermoplastic non-elastomeric polymer blocks made by polymerizing one or more monovinyl aromatic compounds and wherein B represents an elastomeric polymer block prepared either by polymerization of one or more conjugated dienes or by copolymerizing one or more conjugated dienes with one or more monovinyl aromatic compounds, which polymer block B is optionally fully or partially hydrogenated, and (c) an emulsifier characterized by first mixing components (a) and (b) and thereafter is emulsifying this mixture in water in the presence of (c) at a temperature between 100 and 200 ° C and at a pressure above atmospheric pressure. 30? * i. 'Ί 35