Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-04-20
2003-04-15
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S504000, C525S523000, C525S534000, C525S535000, C525S537000, C428S297400
Reexamination Certificate
active
06548608
ABSTRACT:
During the course of a study on pipeline coatings, the Applicant was concerned with polymer compositions. Following this work, compositions of particular interest for coating pipelines, particularly externally, were developed, these compositions containing at least one heat stable thermoplastic polymer which is amorphous or of low crystallinity, and at least one modified epoxy resin.
The present invention concerns polymer compositions, and a process for synthesising these compositions. It also concerns the use of these compositions, in particular for coating conduits, especially pipeline coatings, to obtain pre-impregnates for the production of composition materials, also to produce adhesives and mastics, in particular to rehabilitate oil or geothermal wells or more generally any excavations.
Pipelines are metal tubes, often formed from steel, essentially used in wells to transport crude oil and natural gas, but any type of fluid could be transported by this pipeline. The internal surface of the pipeline is corroded by the transported fluid. When the transported fluid is oil, the sulphur-containing compounds contained in the oil are the main causes of the corrosion. When drilling offshore, the external surface of the pipeline is also corroded by sea water. Treating conduit surfaces has already been described in the prior art. As an example, United States patent U.S. Pat. No. 5,447,798 describes a concrete conduit on which an intermediate layer is deposited which is a mixture of epoxy resin modified by a polysulphide and concrete, then a layer of epoxy resin modified by a polysulphide.
The principal problem with depositing a polymer on a metal surface, for example the external and/or internal surface of a pipeline, for example of steel, is the behaviour of the polymer when it is subjected to heat stress. Even if the oil is cooled before transporting it, the pipeline is often heated to a temperature of about 50° C. to 200° C. by contact with hot oil. Certain polymers, for example polypropylene, tend to deform and no longer adhere to the metal once the temperature exceeds 130° C. Other polymers, such as polyetherimides or polysulphones, adhere at high temperatures but their application temperature (at which it is deposited on the metal) is higher, about 360° C. Further, metals, in particular steel, may undergo phase distortions from a temperature of about 250° C., and certain of their mechanical and physical properties can be altered.
In addition, good adhesion of the polymer at a higher temperature enables the oil to be transported without the need to cool it, or at least it only needs to be cooled to a lesser extent. At a relatively high temperature, oil is less viscous and therefore easier to transport.
The criteria which the desired polymer compositions must satisfy are thus a temperature for deposition on steel such that the steel is not altered and good adhesion to the steel.
The present invention provides a polymer composition which overcomes the above disadvantages. The application temperature at which the polymer composition of the present invention is deposited onto steel is about 180° C. to 250° C., and in that temperature range, the mechanical behaviour of steel is good. The polymer composition of the present invention has particular good adhesion, in particular to steel, high stiffness, and good resistance to sea water. Further, these qualities are not substantially altered when the compositions are aged.
The polymer compositions of the present invention contain at least one heat stable thermoplastic polymer, preferably amorphous, and at least one epoxy resin modified by at least one aromatic polyamine, preferably sterically hindered. The heat stable thermoplastic polymer preferably represents about 15% to 98%, more preferably 35% to 80% by weight, with respect to the total composition weight; preferably, the modified epoxy resin represents about 2% to 85%, more preferably about 20% to 65% by weight, with respect to the total composition weight.
In the present description, the “aromatic polyamine” contains at least two primary amine groups in its molecule. It is preferably sterically hindered, i.e., it contains at least one alkyl substituent containing 1 to 12 carbon atoms located alpha to one of the amine groups.
The most frequently used thermoplastic polymers are polysulphones and polyetherimides.
The term “polysulphone” may be the source of an ambiguity. The first polymer of commercial importance with a base unit containing a sulphone group—SO
2
— was the polymer sold by AMOCO under the trade name UDEL. Because of this, this particular polysulphone is often designated by the generic term polysulphone. In the present description, the term “polysulphone” is used in its generic sense, and not just the limiting sense of a UDEL type polysulphone.
The polysulphones used in the polymer compositions of the invention are preferably aromatic polysulphones and, more preferably, UDEL type polysulphones, RADEL A polysulphone type polyether-sulphones sold by AMOCO, and RADEL R type polyphenylene sulphones also sold by AMOCO.
The polyetherimides used in the polymer compositions of the invention are preferably ULTEM type polyetherimides sold by General Electric Plastics.
These polyetherimides can be used alone, mixed with each other or mixed with other polymers such as polyphenylene ethers, aromatic polyetherketones or polyphenylene sulphides. Polymer compositions of the present invention comprising polyphenylene ethers contain about 5% to 98% by weight thereof with respect to the total weight of the thermoplastic polymers. Polymer compositions of the present invention comprising aromatic polyetherketones contain about 1% to 50% by weight thereof with respect to the total weight of thermoplastic polymers. Polymer compositions of the present invention comprising polyphenylene sulphides contain about 1% to 50% by weight thereof with respect to the total weight of thermoplastic polymers.
The epoxy resins modified by at least one aromatic polyamine, preferably sterically hindered, used in the polymer compositions of the present invention are epoxy resins formed from at least one polyepoxide containing at least two epoxy groups in its molecule and at least one aromatic polyamine, preferably sterically hindered, the mole ratio of the amine to the epoxy being such that each amine group corresponds to 1.6 to 2.6 epoxy groups.
Preferred aromatic polyamines are selected for their low reactivity and for their non toxic nature.
The epoxy resin can be selected from the group formed by the following commercially available resins: the diglycidylether of bis-phenol-A or bis-phenol F, bis-phenol formol epoxy resin, phenol-novolac epoxy resin, cycloaliphatic epoxy resins, tri- or tetrafunctional epoxy resins, resins formed from triglycidylether-isocyanurate and/or triglycidylether-cyanurate and/or triglycidyl-cyanurate and/or triglycidyl-isocyanurate or mixtures of at least two of these epoxy resins.
The epoxy resins obtained from the epoxy resins cited in U.S. Pat. No. 4,921,047 can also be used in the present invention.
The aromatic polyamines used in the polymer compositions of the present invention includes a first series of aromatic amines comprising a single aromatic ring such as 3,5-diethyl-2,4-aminotoluene, 3,5-diethyl-2,6-diaminotoluene and mixtures of these two isomers. Usually, a mixture of these two isomers generally known as DETDA is used.
In the second series of amines used in the present invention, amines containing at least two aromatic rings can be considered, these two aromatic rings generally being connected to each other by a bivalent linear or branched hydrocarbon residue containing 1 to 18 carbon atoms. These two aromatic rings are either connected via a bivalent alkylene group or are connected one to the other via a bivalent linear or branched hydrocarbon residue containing 6 to 18 carbon atoms and containing an aromatic ring.
The aromatic polyamine can also contain at least one substituent selected from the group formed by fluorine, iodine, bromine and chlorine. It prefera
Bonnet Anthony
Camberlin Yves
Grenier Jacky
Pascault Jean-Pierre
Taha Mohamed
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
Sellers Robert E. L.
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