Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1996-12-13
1998-01-13
Szekely, Peter A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524 59, 524 69, C08L 9500
Patent
active
057080623
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to bitumen compositions. Bitumens are useful as sealing materials and for surfacing roads but are often too hard in winter and too fluid in summer. In addition, the coatings must resist cracking when rutted and bitumens exhibit an absence of gelling; it is also important that bitumens should be stable when stored.
The prior art has already proposed bitumens modified with various additives.
Epoxy resins, polyurethanes, rubbers, thermoplastic elastomers and thermoplastic resins are known. However, epoxy resins are not flexible enough, and this causes cracks and poor resistance to inclement weather; on the other hand, they provide good mechanical strength and resistance to alkalis. Polyurethanes have an excellent elasticity but do not stand up to inclement weather and to chemical products and require an excessively long crosslinking time, which is a difficult problem in road surfacing.
U.S. Pat. No. 5,306,750 describes bitumens modified with polymers which have glycidyl (meth)acrylate groups. A storage stability can be obtained but the viscosity is too high when the polymer content exceeds 3%; gelling prevents processing.
Modifiers of the rubber type may be latices or powders of SBR (styrene butadiene rubber), of NR (natural rubber) and SIR (styrene isoprene rubber). This is described in patents JP-B-4024034, JP-B-433120, JP-B-5423691 and JP-A-17618. The thermoplastic elastomers may be block copolymers such as SBS (styrene butadiene styrene), SIS (styrene isoprene styrene) and SEBS (hydrogenated SBS) as described in JP-B-59-13098. The thermoplastic resins may be EVA (ethylene - vinyl acetate copolymer), EEAs (ethylene - ethyl acrylate copolymers), polyethylene or polypropylene, as described in JP-B-60 47404, JP-B-1-15642 and JP-A-63 304059.
The modifiers are generally employed in a proportion of 3 to 7% by weight of the bitumen. However, the proportion must be higher if a better viscosity is wanted; on the other hand, this entails a phase separation of the modified bitumen, that is to say of the mixture of bitumen and of modifier, during transport or storage at high temperature. This results in an inhomogeneous product or a lowering of the melt fluidity.
The other known modifiers are thermoplastic epoxies described in JP-A-503543, JP-A-6116500 and JP-A-6-116333 and combinations of polymers which have glycidyl groups with styrene-based elastomers as described in U.S. Pat. No. 5,331,028. However, these modified bitumens are not sufficiently stable when stored. The modified bitumens of the present invention are stable when stored and exhibit an absence of gelling although the viscosity has been increased. The coatings resist cracking and rutting. The modified bitumens of the invention include, by weight:
(A) 100 parts of bitumen
(B) 0.1 to 10 parts of a copolymer of an alpha-olefin, of an unsaturated epoxide and of an ester of unsaturated carboxylic acid
(C) 0.1 to 10 parts of a copolymer of an alpha-olefin and of an ester of unsaturated carboxylic acid.
The bitumen (A) my be natural or synthetic, for example bitumens for road surfacing, natural bitumens, semiblown bitumen, bitumen partially modified with blown bitumen or any combinations thereof.
The viscosity of (A) at 60.degree. C. is, for example, between 10 and 20000 poises, preferably 300 to 5000 poises.
(B) is a copolymer of an alpha-olefin including at least one unsaturated epoxide and at least one ester of unsaturated carboxylic acid.
The unsaturated epoxide may be chosen from: glycidyl ether, glycidyl maleate and itaconate, glycidyl acrylate and methacrylate, and ether, diglycidyl cyclohexene-4,5-dicarboxylate, glycidyl cyclohexene-4-carboxylate, glycidyl 5-norbornene-2-methyl-2-carboxylate
Glycidyl (meth)acrylate is advantageously employed.
The ester of unsaturated carboxylic acid may be, for example, an alkyl (meth)acrylate, it being possible for the alkyl group to have up to 24 carbon atoms.
Examples of alkyl acrylate or methacrylate which can be employed are especially methyl methacrylate, ethyl acrylate,
REFERENCES:
patent: 5306750 (1994-04-01), Goodrich et al.
patent: 5331028 (1994-07-01), Goodrich
patent: 5556900 (1996-09-01), Goodrich et al.
patent: 5576363 (1996-11-01), Gallagher et al.
patent: 5604274 (1997-02-01), Gallagher et al.
Abstract in English, JP 61-215658.
Brule Bernard
Gazeau Sabine
Komornicki Jacques
Maillet Jerome
Miyaki Yoshiyuki
Elf Atochem S.A.
Enterprise Jean Lefebvre
Szekely Peter A.
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