PROCESS FOR PREPARING A MODIFIER FOR BITUMEN AND PRODUCT OBTAINED THEREFROM

Abstract: Process for preparing a modifier for bitumen, consisting of: mixing a socalled ''lubricating fraction'' composed of lubricating liquids derived from oil or synthetic products with polymers or polymer mixtures which can be attacked by the ''lubricating fraction'' and with other additives such as atactic ehylene-propylene copolymers, polyolefins, polystirene, polydiene; melting said solid components to make them homogeneous to one another; casting said components in cake-shaped moulds or reducing them to grains; cooling said mixture to room temperature. The obtained product is a modifier to be successively added to bitumen in order to provide impermeable sheaths or other impregnating products, conglomerates or featheredges.

Description: PROCESS FOR PREPARING A MODIFIER FOR BITUMEN AND PRODUCT OBTAINED THEREFROM. This invention relates to a process for preparing a modifier adapted to mainly improve the physical-chemical, technological, mechanical properties of bitumen as well as the modifier provided by such a process. Bitumen, which is formed of the residue of the natural or industrial oil evaporation, exhibits by nature the properties of being impermeable to water and other atmospheric agents as well. It was really used up to 30-40 years ago either alone or together with a reinforcement of cardboard or fiber glass in the building industry as well as when a building should be protected. Bitumen exhibits, however, some properties limiting its capability of being used such as e.g. the brittleness at temperatures even higher than 0°C, the tendency to be deformed (high penetrability, ductility) and so on. Therefore, modifiers directed to improve the most important properties have been studied for the last decades. Generally these modifiers are formed of polymers of various kind showing better properties of cold-flexibility and mechanical strength as well. Researches have been carried out for long time to provide such a modifier prepared bv ixinσ different fractions cf polyolefins. A modifier able to improve the properties of the bitumen for the i permeabilization has been already prepared by mixing and melting at about 180°C suitable quantities of atactic polypropylene with the addition of additives, such as polypropylene wax, with small quantities of bitumen having the main function of fluidizing and dying agent, and by cooling such a mixture. However, it has been proved for years that manufacturers of polypropylene direct their efforts towards greater and greater yields of isotactic polypropylene to the detriment of the atactic fraction. This invention seeks to provide a process and a product which can successfully replace the raw materials used as mentioned above for the production of conventional modifiers for bitumen. The process of this invention seeks to replace those polypropylene fractions (atactic polypropylene) which can be found on the market with ever-growing difficulty with a mixture of hydrocarbons from the distillation of crude oil which is destined to form the socalled "lubricating fraction" of the additive for bitumen. In other words it is that fraction which distills between 200 and 500°C in the oil treatment. In practice the isotactic polypropylene has been solubilized according to this invention with different kinds of oil, from the most fluid to the most viscous, from diathermic oils to piston oils, from lubricating motor oils to oils for compressors. It was experimentally found that by using materials thrown on the market with the name of "synthetic oils" the results could be perfectly compared with those achieved by using oils from petroliferous products. It was further found that the previous story of the used oil has no influence (i.e. wheter it is pure, restored or exhausted oil) provided that it has kept its solvent capability. It should be appreciated that by mixing suitable quantities of the above mentioned "lubricating fraction" with isotactic polypropylene a modifier for bitumen is produced having particular properties, i.e. the capability of providing a material which is extremely elastic at low temperatures, even much lower than 0°C. It was sufficient to add small quantities of atactic ethylene-propylene copolymer to the preceding mixtures to provide a modifier repeating or improving the physical-mechanical properties of the product of the previous art. The researches have been extended from such first experiments to all the available polyolefin polymers, in particular to the high and low density polyethylene, thus detecting that the "lubricating fraction" showed a remarkable solvent capability and a very good compatibility. The use of the "lubricating fraction" has been extended with success to the polyolefin copoly ers, polystirene, polydiene and copolymers thereof. By using polydiene (natural or synthetic rubber) alwavs together with the - - "lubricating fraction" and the isotactic polypropylene the use of atactic polyethylene-propylene copolymers can be avoided, thus getting away from the by-products of the polymerization of the isotactic polypropylene. Among the advantages in the production of a modifier for bitumen according to this invention besides the above mentioned, non-negligible possibility of replacing raw materials which are hardly to be found, following advantages are to be mentioned: the recycle of mineral or synthetic oils even though they are exhausted, said oils being available in large quantities; the capability of said oils to attack the above mentioned polymers which cannot be mixed with bitumen, thus causing the solubilization thereof; the better use, in the production of a modifier, of a raw material at the liquid state as far as the stockage, displacement, mixing and after all every step of the treatment thereof is concerned. It should be further appreciated that the advantages coming from the constant qualities of oils of the "lubricating fraction", unlike the continuous variability of atactic polypropylene depending on the origin thereof, allow the quality of the waterproofing sheats as final products obtained with the bitumen provided with additives according to the invention to be improved as far as the aging under atmospheric conditions and the mechanical properties, in particular the flexibility, is concerned. Therefore, this invention provides a process for preparing a modifier adapted to improve the properties of bitumen destined to waterproofing sheaths, impregnating products, conglomerates, featheredges and the like, comprising following steps: mixing a "lubricating fraction" formed of either pure or restored or exhausted oils from the distillation of petroleum or synthetic oils with polymers which can be attacked by said "lubricating fraction" and mainly consisting of isotactic polypropylene, polystirene and mixtures thereof as well as with other additives such as atactic polypropylene omopolymers and atactic ethylene- propylene copolymers, polyolefins, polystirene, polydiene, bitumen, afterwards socalled "additives"; melting said mixture by increasing temperature up to about 180°C; casting and cooling said mixture in cakes or grains. The modifier provided by the process of this invention can have following composition: lubricating fraction: 1 - 85% attackable polymers: 1 - 70% additives: 1 - 90% The selection of specific percent values regarding each component is depending on the requested modifier, the function performed when mixed with bitumen as well as particular needs of users. As a way of example some formulations are indicated: lubricating fraction: 60 - 80% attackable polymers: 15 - 30% additives: 5 - 10% This is a more fluid modifier designed to be used as corrective agent for harder bitumen. lubricating fraction: 30 - 55% attackable polymers: 35 - 50% additives: 10 - 20% Such modifiers can be used in combination with softer bitumen.

Claims: CLA I MS 1. Process for preparing a modifier for bitumen, characterized by the mixing of: a) a "lubricating fraction" essentially formed of mineral and synthetic, pure or restored or exhausted oils; b) polymers which can be attacked by said "lubricating fraction" and essentially consisting of isotactic polypropylene, polyethylene and mixtures thereof; c) additives consisting of atactic omopolymers, atactic _ polyethylene-polypropylene copolymers, polyolefins, polystirene, polydiene, bitumen and polymers thereof; said resulting mixture being then melted, made homogeneous, cast and cooled in cakes or grains. 2. Process according to claim 1,. characterized in that when said mixture is being mixed and made homogeneous, the temperature thereof is increased to about 180°C. 3. Modifier for bitumen, characterized by following composition: a) a "lubricating fraction" essentially formed of mineral and synthetic, pure or restored or exhausted oils; b) polymers which can be attacked by said "lubricating fraction" and essentially consisting of isotactic polypropylene, polyethylene and mixtures thereof; c) additives formed of atactic omopolymers, atactic polyethylene-polypropylene copolymers, polyolefins, polystirene, polydiene, bitumen and polymers thereof. 4. Modifier for bitumen according to claim 3, characterized in that the "lubricating fraction" is in the range between 1 and 85%. 5. Modifier for bitumen according to claim 3, characterized in that the attackable polymers are in the range between 1 and 70%. 6. Modifier for bitumen according to claim 3, characterized in that the additives are in the range between 1 and 90%. 7. Modifier for bitumen according to claims 4, 5 and 6, characterized in that the "lubricating fraction" is in the range between 60 and 80%, the attackable polymers are in the range between 15 and 30% and the additives are in the range between 5 and 10%. 8. Modifier for bitumen according to claim 4, 5 and 6, characterized in that the "lubricating fraction" is in the range between 30 and 55%, the attackable polymers are in the range between 35 and 50% and the additives are in the range between 10 and 20%. 9. Bitumen composition, in particular adapted for waterproofing sheaths, various impregnating products, conglomerates of featheredges and the like, characterized in that it consists of a modifier for bitumen according to any claim 3 to 8.

Inventors: BORIA LUIGI, BOTTALLI RENATO, BROUSSARD GABRIELE, BORIA, LUIGI, BOTTALLI, RENATO, BROUSSARD, GABRIELE
Applicants: INTERCHIMICA SPA, INTERCHIMICA S.P.A.
Application year: 1988
Main classification: C08L95
IPC codes: C08L95