Porphyrinogenic resin systems and polymers derived therefrom

Details Porphyrinogenic resin systems and polymers derived therefrom Porphyrinogenic resin systems and polymers derived therefrom

1994-09-22

2001-05-22

Hampton-Hightower, P. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From ketone or ketene reactant

C528S125000, C528S126000, C528S128000, C528S172000, C528S173000, C528S179000, C528S180000, C528S187000, C528S228000, C528S327000, C525S471000, C525S480000, C524S606000, C524S700000, C524S770000

Reexamination Certificate

active

06235868

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to porphyrinogenic resin systems and methods for their manufacture, and to coating compositions and methods involving such resins. The invention is particularly concerned with anti-corrosion coatings, derived from such resins.
BACKGROUND OF THE INVENTION
In International Patent Application No. PCT/AU91/00298, we described how the condensation of a beta-unsaturated aldehyde, especially crotonaldehyde, and pyrrole can give rise to a monomeric product which contains porphyrin-bearing unsaturated substituents. This monomeric material, which we referred to as a “polymerisable porphyrin”, then readily polymerises to produce polymeric product.
Polymers made from the monomeric material, or copolymers formed from the polymerisable material and at least one other polymerisable monomer of a known type, can be used in the production of films, coatings and other structures.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide polymerisable resins and/or compositions derived from them which have improved properties such as, for example, improved anti-corrosion properties.
We have found that this and other objectives can be achieved by reacting a cyclic ketone with pyrrole or an N-alkyl pyrrole, either of which may contain one or more suitable substituents, or a mixture of two or more such pyrroles.
Thus according to one aspect of the present invention, there is provided a polymerisable resin comprising a porphyrinogenic ring system produced by the reaction of:
(a) one or more compounds selected from the group consisting of pyrrole and N-(lower)alkyl pyrroles, any of which may be ring substituted with one or more non-deleterious substituents, with
(b) a C
4
-C
6
saturated alicyclic ketone which is capable of reacting with the 2 or 5 position of the pyrrole ring.
DETAILED DESCRIPTION OF THE INVENTION
The reaction generally requires the presence of an acid catalyst, which is selected to suit the particular chosen reagents (a) and (b). The catalyst may be an inorganic acid, or an organic acid, such as acetic or propionic acid, or an acid anhydride, such as phthalic anhydride. Organic acids which contain unsaturated groups may be used. These acids may become incorporated into and provide functional groups in the resin product, as well as providing a catalytic function. Acids containing vinyl groups, such as acrylic acid, or triple bonds, such as acetylene dicarboxylic acid, are especially useful in this regard.
Inorganic acids, especially the hydrohalic acids, such as hydrochloric acid, may also be used either alone or with an organic acid, as described above. Mixtures of an inorganic acid, e.g. HCl, and an unsaturated aliphatic aldehyde, such as acrolein or crotonaldehyde, are also effective catalysts.
Where the reactant (a) is or includes an N-alkylpyrrole, the acid catalyst also has the important function of removal of the alkyl group to allow reaction of the dialkylated pyrrole intermediate with the ketone to give the porphyrinogenic ring system. Hydrochloric acid is especially useful in this regard, particularly when used with cyclohexanone or other cyclic ketones which act as co-solvents for the (normally immiscible) aqueous acid and N-alkylpyrrole.
The preferred cyclic ketone is cyclohexanone.
The extent of the reaction may be controlled by adding one or more suitable reagents which effectively terminate the polymerisation. For example, addition of a C
1
-C
8
aliphatic alcohol, such as butanol, results in “end-capping” of the carboxyl group of an organic acid catalyst. When an inorganic acid catalyst is used, addition of a saturated cyclic monoether, such as tetrahydrofuran (THF), results in ring opening of the cyclic ether by the acid, and the acid is thereby removed from the reaction system. For example, when the catalyst is HCl, reaction with THF results in the formation of 1-chlorobutanol.
The term “porphyrinogenic ring system” as used herein means a porphyrinogen or porphyrinogen-like ring system comprising 5-membered heterocyclic rings linked in a macrocyclic ring structure by linking groups. The linking groups have unsaturated side chains and &pgr;-covalent bonding is formed between the macrocyclic ring and the double bonds of the side chains. The porphyrinogenic ring system should also have sufficient electrons to form covalent or coordinate bonds with metals, e.g.>N—M—N<, where M is a metal.
Generally the porphyrinogenic ring system contains four 5-membered heterocyclic rings. When the ketone is cyclohexanone, there will also be four 6-membered carbocyclic rings, comprising the linking groups.
The term “non-deleterious substituent” means a substituent which does not interfere with formation of the porphyrinogenic ring system or the subsequent reaction of the resin product with other materials, as described hereinafter.
In one preferred aspect of the invention the porphyrinogenic resin is obtained by the reaction of pyrrole, N-methylpyrrole, or a mixture of the two, with cyclohexanone in the presence of an acid catalyst.
The resin product may be modified by reaction with one or more acrylic monomers, for example butyl acrylate or acrylic acid. Alternatively, the pyrrole (or other reagent (a)) may be reacted with the modifier before or during reaction with reagent (b), to achieve the desired modification.
The resin products of the invention can be used alone as coating compositions or as part of a coating system. Advantageously, they may be combined with other materials for this purpose, including known coating materials or compositions, or precursors of such materials. Thus coating systems of many kinds can be advantageously formulated using the resin products of this invention. Such coating systems include, for example, combinations of the porphyrinogenic resins with epoxy, phenolic- or alkyd-based resins of known types.
Coatings or coating compositions in accordance with this invention find applications in a variety of fields, for example, they can be used in the paint industry generally and especially in anti-corrosion coatings for metals in the automotive, marine and general engineering industries. They can be utilised as decorative or protective coatings on various substrates, such as metals, paper and ceramics. They can be used as insulating coatings or as coatings for printing or masking substrates, e.g. in processes involving etching.
In particular, the resin products of the invention can be reacted with other unsaturated polymeric or polymerisable materials. Among the reagents which can be used for this purpose are polymerisable monomers, oligomers or other polymer precursors which possess appropriate reactive groups. Oligomer types which contain such groups include:
(i) melamine based oligomers
(ii) epoxy oligomers
(iii) polyurethane oligomers or
(iv) alkyd resin precursors.
Oligomers may be terminated (“end capped”) or reactive.
Preferred oligomer types are the alkyd resin precursors, such as acrylic-melamine, melamine-alkyd or simple alkyd formations.
Examples include castor oil base alkyds, soya bean oil alkyds, rosin esters, —OH rich esters and COOH rich esters (rosin precursors), —OH deficient and —COOH deficient resins.
Such reactions may require the presence of a catalyst. Inorganic acids, such as HCl or organic acids, especially acrylic acid, may be used as catalysts. Metal salts are also useful as catalysts, particularly salts of the Transition Metals (Groups 3 to 12 of the Periodic Table) and the heavier metals of Group 14. Apart from acting as catalysts, these metals can also form coordination complexes with porphyrinogenic moieties, giving rise to coloured products which are useful in coating formulations.
Conveniently, the metal halides may be used, examples of which are the chlorides of copper, iron(III), molybdenum, nickel, manganese, mercury and lead. The resin products of the invention have also been found to be capable of undergoing further reaction with metal surfaces and to thereby form strongly adherent coatings which are highly resistant to saline solutions and other corr

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