Data processing: measuring – calibrating – or testing – Calibration or correction system – Fluid or fluid flow measurement
Reexamination Certificate
1998-09-10
2001-01-09
Williams, Hezron (Department: 2856)
Data processing: measuring, calibrating, or testing
Calibration or correction system
Fluid or fluid flow measurement
Reexamination Certificate
active
06173237
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to the manufacture of bitumen/polymers mixtures, notably designed for the production of roofing sealing membranes.
DESCRIPTION OF THE RELATED ART
The polymers used in these mixtures can be of various natures. Recycled polymers or polymers in the form of waste are classically used in order to reduce the cost of raw materials.
We can also mention the APP (atactic polypropylene) which constitutes a manufacture waste of the IPP (isotactic polypropylene).
The physical characteristics of these recycled polymers are not constant. Still, the manufacturers of sealing membranes must respect the technical specifications and guarantee the quality of their products.
The manufacturers have only empirical means in order to forecast the physical characteristics of a bitumen/polymers mixture, when the quantity of the polymers is caused to vary or when the nature of the polymers is modified.
For each new polymer or for each new delivery of a recycled polymer or of a polymer in the form of waste, the manufacturers must perform tests in order to adjust the quantity of polymers in the mixture. Moreover, in practice, the polymers are used in excess in order to guarantee the quality of the finished product, which increases the costs. Finally, frequent and expensive quality checks are necessary.
When a quality check shows that the characteristics of the bitumen/polymers mixture do not comply with the technical specifications, once again empirical means are implemented to correct the mixture, among other things by incorporating additional quantities of polymers.
In the relatively old technical field of sealing membranes, these empirical means for determining bitumen/polymers mixtures are the only ones to be used. The number of tests is also limited not to block the production.
The implementation of more rational methods is, generally, rejected, taking into account the risks of slowing down the manufacture.
SUMMARY OF THE INVENTION
The purpose of the invention is to remedy these shortcomings while offering a process to determine the influence of the percentage of the different polymers of a bitumen/polymers mixture on at least one physical characteristic of the mixture, on the basis of a limited number of tests which are carried out to establish a reference model, for the polymers and the bitumen under consideration.
Thus, the process according to the invention consists in:
performing a limited number of bitumen/polymers mixtures, according to the test schemes method, whereby the polymers and the bitumen are identical in all the mixtures and whereas the respective percentages of the polymers can be set to a maximum level or to a minimum level, of a range of values to be determined in advance for each of them,
measuring the said physical characteristic(s) for each of the said mixtures,
and deducing, by statistical calculations, a modelling of the said physical characteristic(s).
The process according to the invention exhibits the advantage of being able to take into account the influence of another polymer, which would be introduced into the mixture.
The process then consists moreover in:
performing at least four additional mixtures incorporating another polymer,
measuring the said physical characteristic(s) for each of these additional mixtures,
and deducing the changes to make to the modelling of the said physical characteristic(s), to take into account the introduction of this other polymer.
The process according to the invention is not limited to the introduction of a single other polymer, whereas the previous phases of the process can be repeated for any other polymer which should be introduced into the mixture.
The bitumen/polymers mixture can contain fillers. The percentage of fillers in the mixture may be constant.
The physical characteristic(s) of the mixture is (are) notably flexibility at low temperature in mint condition and in aged condition, Brookfield viscosity at 180° C., penetration at 25° C. and 60° C. and/or softening temperature.
As regards the manufacture of sealing membranes, the polymers of the said bitumen/polymers mixture are selected, for exemplification purposes, among the APP, IPP and the copolymers of ethylene/propylene type.
The invention also relates to a process for the determination of at least one physical characteristic of a bitumen/polymers mixture according is to the polymers used.
This process consists in:
implementing the process according to the invention for determining the influence of the percentage of the different polymers of the mixture on the said physical characteristic(s),
and fixing the percentages of each polymer in order to derive the value of the said physical characteristic(s).
The invention also relates to a process for obtaining a bitumen/polymers mixture exhibiting one(several) desirable physical characteristic(s) of the mixture
The process consists in:
implementing the process according to the invention for determining the influence of the percentage of the different polymers of the mixture in the said physical characteristic(s),
fixing a range of values for the said characteristic(s) and
deriving the percentage of each polymer in the mixture.
This process consists in determining the percentages of the polymers while taking their cost into account.
These processes enable to maximize the bitumen/polymers mixtures in terms of quality and of cost of raw materials, while remaining fast and cheap to be implemented.
The invention also relates to a process for modifying a bitumen/polymers mixture exhibiting one (several) determined physical characteristic(s) to be modified.
This process consists in:
implementing the process according to the invention to determine the influence of the percentage of the different polymers of the mixture on the said physical characteristic(s),
fixing other values of the said physical characteristic(s) of the said mixture and
calculating the additional quantity of at least one polymer to be added to the said mixture so that it exhibits physical characteristics of values more or less equal to these other values.
All these processes call for prior determination of the influence of the different polymers on the mixture, but their implementation does not require any complementary test during manufacture.
The invention will be understood better and other aims, advantages and characteristics of the former will appear more clearly when reading the detailed description, which follows.
Maximization of the bitumen/polymers mixtures requires knowing the influence of each of the constitutive parts of the mixture on the physical characteristics of the former.
The physical characteristics adopted are for instance imposed by standards or classically selected by the manufacturers.
The following can be mentioned, among others:
flexibility at low temperature (expressed in degrees Celsius) in mint condition and in aged condition (after 4 weeks at 80° C.), measured according to a so-called UEATC (Union Europ{acute over (e)}enne des Agr{acute over (e)}ments Techniques de la Construction—European Union of the Technical Building Permits),
Brookfield viscosity at 180° C. (expressed in centipoises), measured with a rotary viscometer (pointer 28, speed 50 rpm),
penetration at 25° C. and at 60° C. (expressed in deci mm), measured according to the standard NFT 66-004,
softening temperature (expressed in degrees Celsius), measured according to the standard NFT 66-008.
Inasmuch as the physical characteristics of the polymers-modified bitumen depend on the nature of each polymer and on its percentage in the mixture, as well as on the bitumen selected, the theoretical number of tests is enormous in order to establish sound modelled physical characteristics. This acts as a deterrent for the man of the art and this is the reason why no model has been developed in this technical field.
REFERENCES:
patent: 3853800 (1974-12-01), Haberl
patent: 3887422 (1975-06-01), Bosniack
patent: 3917895 (1975-11-01), Bosniack
patent: 3960793 (1976-06-01), Bosniack
patent: 4357169 (1982-11-01), Trujillo
patent: 5326798 (19
Onduline
Politzer Jay L.
Williams Hezron
Young & Thompson
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