Pipes and tubular conduits – Distinct layers – Bonded to each other
Reexamination Certificate
1999-01-22
2002-02-26
Chen, Vivian (Department: 1773)
Pipes and tubular conduits
Distinct layers
Bonded to each other
C138S145000, C138S146000, C428S035700, C428S035800, C428S411100, C428S413000, C428S418000, C428S457000
Reexamination Certificate
active
06349747
ABSTRACT:
During the course of a study on surface coatings, the Applicant was concerned with polymer compositions. Following this work, compositions of particular interest for surface coatings were developed, these compositions containing at least one thermoplastic polymer which is usually amorphous or of low crystallinity, and at least one epoxy resin modified by at least one aromatic polyamine.
The present invention concerns the use of these compositions to coat metal or other surfaces, for example for receptacles or conduits. These compositions are particular suitable for protecting surfaces, in particular metal surfaces. These compositions are used to coat conduits and pipelines in particular, especially metal conduits and steel pipelines.
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 such pipelines. 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.
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 distort 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 particlar steel—frequently used in the production of pipelines—, 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 use of the polymer compositions of the present invention overcomes the above disadvantages; in particular, such use produces pipelines with a coating with good adhesion, good stiffness, and good resistance to sea water. Further, the properties of the polymer compositions used are only slightly altered when these compositions are aged.
The polymer compositions used contain at least one thermoplastic polymer, usually having a high glass transition temperature and preferably being amorphous or of low crystallinity, usually selected from the group formed by polysulphones, polyetherimides and polyphenylene ethers and at least one epoxy resin modified by at least one aromatic polyamine containing at least two primary amine groups in its molecule; preferably, sterically hindered polyamines are selected, i.e., they contain at least one alkyl substituent containing 1 to 12 carbon atoms located alpha to one of the amine groups. In the remainder of the description, the polyamines described above are termed “aromatic polyamines”.
Preferably, the polymer compositions used contain at least one thermoplastic polymer in an amount of about 15% to 98% by weight, more preferably 30% to 70% by weight, with respect to the total composition weight, and at least one epoxy resin modified by at least one aromatic polyamine in an amount of about 2% to 85% by weight, preferably about 30% to 70% by weight, with respect to the total composition weight.
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, more preferably UDEL type polysulphones, RADEL A polysulphone type polyether-sulphones sold by AMOCO, and RADEL R polysulphone type polyphenylene sulphones also sold by AMOCO.
The polyetherimides used in the polymer compositions are preferably ULTEM type polyetherimides sold by General Electric Plastics.
The polyphenylene ethers used in the polymer compositions are preferably PPE 800 type polyphenylene ethers sold by General Electric Plastics.
As used in the present invention, the thermoplastic polymers can be used alone, mixed with each other or mixed with other polymers such as aromatic polyetherketones or polyphenylene sulphides. Polymer compositions comprising aromatic polyetherketones contain about 1% to 50% by weight thereof with respect to the total weight of thermoplastic polymers. Polymer compositions 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 are epoxy resins formed from at least one polyepoxide containing at least two epoxy groups in its molecule and at least one aromatic polyamine containing at least two primary amine groups in its molecule, and at least one alkyl substituent containing 1 to 12 carbon atoms located alpha to one of the amine groups, the mole ratio of the amine to the epoxy being such that each amine group corresponds to 1.6 to 2.6 epoxy groups.
The 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 resin, phenol-novolac resin, cycloaliphatic resins, tri- or tetrafunctional 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 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 include a first series of aromatic amines comprising a single aromatic ring such as 3,5-diethyl-2,4-dinitrotoluene, 3,5-diethyl-2,6-diaminotoluene and mistures of these two isomers. Usually, a mixture of these two isomers generally known as DETDA is used.
In a second series of amines used, 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 alkyl 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 amine can also contain at least one substituent selected from the group formed by fluorine, iodine, bromine and chlorine. It preferably contains at least two alkyl substituents, each being alpha either side of an amino group.
When the two aromatic rings are connected via a bivalent alkyl residue, this residue is preferably a methylidene group which is non substituted or substituted by at least one radical selected from alkyl radicals and halogenoalkyl radicals containing 1 to 3 carbon atoms. As an example, this alkyl residue is selected from the group formed by the methylidene group, the isopropylidene group, the halogenoisopropylidene groups, and the hexafluoroisopropylidene group. In this case, the amine is preferably selected
Bonnet Anthony
Camberlin Yves
Grenier Jacky
Pascault Jean-Pierre
Poncet Stéphane
Ahmed Sheeba
Chen Vivian
Institut Francais du Pe'trole
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