Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-09-13
2001-05-22
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S059000, C524S575000, C525S314000
Reexamination Certificate
active
06235817
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to polymer-modified bituminous compositions, used for roofing and waterproofing membranes or material.
BACKGROUND OF THE INVENTION
Physical properties of a bituminous composition used for roofing and waterproofing membranes or material such as low temperature break resistance, flexibility, high temperature flow resistance and vicinity can be improved, as disclosed in U.S. Pat. No. 4,530,652, by incorporating radial elastomeric block copolymers whose structure is defined by the general formula (A-B)
n
Y wherein Y is the residue of a polyfunctional coupling agent, (A-B) represents a single arm constituted of a polydiene block B and a polyvinyl aromatic endblock A, and “n” represents the number of arms (A-B).
Bituminous compositions comprising such copolymers, when used for roofing or waterproofing membranes, provide indeed good performance properties. However, the latter are obtained at the detriment of other physical properties ling their broader applications. For example, when those elastomeric block copolymers are added to a bituminous material to improve high temperature properties, the low temperature performance is impaired. Likewise, when both high and low temperature properties are met, the viscosity of the roofing material is such as to render its handling inoperable with standard equipment
In U.S. Pat. No. 4,196,115, two radial elastomeric block copolymers, one having a low, the other having a high molecular weight, (or, alternatively, one radial of high molecular weight and one linear elastomeric block copolymer of low molecular weight) are blended together with a bituminous component to prepare a roofing material. Both copolymers are selected in such a way that the final bituminous composition yields the desirable high and low temperature properties satisfying tests which determine the said properties for ultimate use of the roofing membranes.
Unfortunately, this process implies the mixture of at least two compounds, namely two separately-prepared copolymers, with a bituminous component in order to obtain compositions that give the desired properties to the final membranes.
The present invention aims at new bituminous compositions which enable to enlarge the range of service temperatures of roofing and waterproofing membranes or material, without impairing appropriate viscosities that allow an easy handling with standard installation equipment, by proposing bituminous compositions that do not require the presence of two or more separately-prepared (co)polymers in bituminous compositions in order to be especially suitable to those applications.
An objective of this invention is to provide improved bituminous compositions which are suitable for roofing and waterproofing material or membranes.
A further objective of this invention is to disclose a bituminous composition which does not require the presence of more than one copolymer component.
A further objective of this invention is to enlarge the range of the working temperatures for roofing and waterproofing membranes or material which are made from these bituminous compositions.
A further objective of this invention is to ensure appropriate dynamic viscosities to the bituminous composition such that an easy handling of the ultimate roofing and waterproofing material or membranes be possible with standard installation equipments.
SUMMARY OF THE INVENTION
The present invention relates to bituminous compositions, used for roofing and waterproofing membranes or material, which consist of a bituminous component and one or more rubbery components constituted of coupled polyvinyl aromatic polydiene block copolymers having an asymmetrical structure, the term “asymmetrical” meaning that the endblocks in the molecular stature are polyvinyl aromatic segments of at least two different lengths, one short and one long.
More particularly, the bituminous composition of this invention is constituted of a bituminous component and elastomeric block copolymers whose molecular structures are described by the general formula (A
1
—X
1
)
n
Y in which Y represents the residue of a coupling agent, “n” is the functionality number of said coupling agent and the number of arms (A
1
—X
1
), A
1
represents polymeric endblocks of monovinyl aromatic monomers, and X
1
elastomeric segments. These asymmetrical elastomeric block copolymers are characterised by endblocks A
i
having at least two different molecular weights, one “high” and one “low”.
It has been unexpectedly found that improved physical properties at both high and low temperature of a bituminous composition are obtained by incorporating small amounts of such asymmetrical elastomeric block copolymers in a bituminous composition. The copolymer-containing bituminous composition obtained by this invention is surprisingly provided with all the desired physical performance that gives to final roofing and waterproofing membranes or material, broader ranges of working temperatures and appropriate dynamic viscosities required by standard application equipments. The improved ranges of service temperatures, which are defined as the difference between the softening point and the cold-bending temperature, give to the ultimate membranes both good high and low temperature performance so that they can be used under prevailing environmental conditions in any geographical location.
DETAILED DESCRIPTION OF THE INVENTION
In the following description, the peak molecular weights M
p
of copolymers or polymeric segments are peak molecular weights that appear on the molecular weight distribution curve generated by Gel Permeation Chromatography analyses that are performed on those copolymers or segments.
The bituminous compositions of the invention essentially consist of (I) a bituminous component having a penetration grade according to ASTM D5-75 ranging from 3 to 30 mm at 25° C., and (II) at least one block copolymer constituted of polymerised monomer units of (a) at least one monovinyl aromatic hydrocarbon and (b) at least one conjugated diene, the said block copolymer comprising from 50 to 82% by weight of polymerised monomer (b), having a peak molecular weight ranging from 75000 to 350000, and having the general formula (A
i
—X
i
)
n
Y in which Y represents the residue of a coupling agent, “n”, greater than one, is the functionality number of said coupling agent and the number of arms (A
i
—X
i
) wherein “i” is an integer ranging from 1 to “n”, A
i
represents polymeric endblocks of monovinyl aromatic monomers (a), and X
i
elastomeric segments essentially constituted of polymerised conjugated diene monomers (b), the total amount of copolymer (II) in the bituminous component (I) ranging from 1 to 20% by weight of the total (I)+(II), the bituminous compositions being characterised in that the said copolymer contains blocks A
i
having at least two different peak molecular weights, at least one being comprised between 15000 and 60000 and at least one being comprised between 5000 and 25000, the ratio (c) of the highest to the lowest peak molecular weight being equal to or greater than 1.2, and the number (d) of blocks A
i
having a molecular weight above the number average molecular weight of blocks A
i
and that (e) of blocks A
i
having a molecular weight below said average each represent at least 5% of the total number of polymeric endblocks A
i
.
Structural Definition of the Copolymers
The compositions of this invention essentially contain a bituminous component and asymmetrical coupled elastomeric block copolymers whose structure is described by the general formula (A
i
—X
i
)
n
Y in which Y represents the residue of a coupling agent, “n” is the functionality number of this coupling agent and the number of arms (A
i
—X
i
) wherein “i” is an integer ranging from 1 to “n”, A
i
represents polymeric blocks of monovinyl aromatic monomers, and X
i
elastomeric segments essentially constituted of polymerised conjugated diene monomers.
The term “asymmetrical” means that the endblocks A
i
, in the molecular structure described hereabove, have at least t
Hallet Jean-Philippe
Haveaux Bernard
Lanza Emmanuel
Noiret Andre
Fina Research S.A.
Szekely Peter
Wheelington Jim D.
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