Compositions and methods for forming articles having silver metal
Electrically-conductive silver metal can be provided in a thin film or pattern on a substrate from a silver complex having reducing silver ions and represented by: (Ag + ) a (L) b (P) c (I) wherein L represents an α-oxy carboxylate; P represents a 5- or 6-membered N-heteroaromatic compound; a is 1 or 2; b is 1 or 2; and c is 1, 2, 3, or 4, provided that when a is 1, b is 1, and when a is 2, b is 2. The silver complex is mixed in a hydroxy-free, nitrile-containing aprotic solvent with a polymer that is either (i) a hydroxy-containing cellulosic polymer or (ii) a non-cellulosic acrylic polymer having a halo- or hydroxy-containing side chain. The reducible silver ions in the a thermally sensitive thin film or pattern can be thermally converted to electrically-conductive metallic silver under suitable heating conditions to provide a product article that can be used in various devices.
1. A non-aqueous precursor composition consisting essentially of:
(a) a silver complex comprising one or more reducible silver ions that are present in an amount of at least 30 weight % and up to and including 90 weight %, based on the total weight of the non-aqueous precursor composition, which one or more reducible silver ions are complexed with an α-oxy carboxylate and a 5- or 6-membered N-heteroaromatic compound,
the silver complex being represented by the following formula (I):
(Ag + ) a (L) b (P) c (I)
wherein L represents the α-oxy carboxylate; P represents the 5- or 6-membered N-heteroaromatic compound; a is 1 or 2; b is 1 or 2; and c is 1, 2, 3, or 4, provided that when a is 1, b is 1, and when a is 2, b is 2;
(b) a hydroxy-free, nitrile-containing aprotic solvent having a boiling point at atmospheric pressure of at least 100° C. and less than 500° C.; and
(c) a polymer that is either (i) a hydroxy-containing cellulosic polymer or (ii) a non-cellulosic acrylic polymer having a halo- or hydroxy-containing side chain, which polymer is present in an amount of at least 0.25 weight % and up to and including 15 weight %, based on the total weight of reducible silver ions in the silver complex,
wherein L is represented by the following formula (II):
wherein R 1 , R 2 and R 3 are independently hydrogen or branched or linear alkyl groups, or by the following formula (III):
wherein R 4 is a branched or linear alkyl group having 1 to 8 carbon atoms and any of the hydrogen atoms in the R 4 branched or linear alkyl group optionally can be replaced with a fluorine atom, and
P is selected from the group consisting of pyridine, 2-methylpyridine, 4-methylpyridine, 2,6-dimethylpyridine, 2,3-dimethylpyridine, 3,4-dimethylpyridine, 4-pyridylacetone, 3-chloropyridine, 3-fluoropyridine, oxazole, 4-methyloxazole, isoxazole, 3-methylisoxazole, pyrimidine, pyrazine, pyridazine, and thiazole.
2. The non-aqueous precursor composition of claim 1 , wherein the (i) hydroxy-containing cellulosic polymer is selected from the group consisting of hydroxypropyl methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, and mixtures thereof.
3. The non-aqueous precursor composition of claim 1 , wherein the (ii) non-cellulosic acrylic polymer comprises recurring units derived from one or more (meth)acrylates, at least one of which (meth)acrylates comprises a halo- or hydroxy-containing side chain.
4. The non-aqueous precursor composition of claim 1 , wherein the (i) or (ii) polymer is present in an amount of at least 2 weight % and up to and including 15 weight %, based on the total weight of reducible silver ions in the silver complex.
5. The non-aqueous precursor composition of claim 1 , wherein the hydroxy-free, nitrile-containing aprotic solvent is acetonitrile, benzonitrile, butyronitrile, propionitrile, isovaleronitrile, or valeronitrile or a mixture of two or more of these.
6. The non-aqueous precursor composition of claim 1 , wherein: the hydroxy-free, nitrile-containing aprotic solvent is acetonitrile; P is selected from the group consisting of pyridine, 2-methylpyridine, 4-methylpyridine, 2,6-dimethylpyridine, 2,3-dimethylpyridine, 3,4-dimethylpyridine, 3-chloropyridine, and 3-fluoropyridine; and the (c) polymer is hydroxypropylmethyl cellulose.
7. The non-aqueous precursor composition of claim 1 , wherein R 1 is hydrogen or a branched or linear alkyl group having 1 to 3 carbon atoms, and R 2 and R 3 are independently branched or linear alkyl groups having 1 to 8 carbon atoms, wherein any of the hydrogen atoms in the R 1 , R 2 , and R 3 branched or linear alkyl groups optionally can be replaced with a fluorine atom.
8. The non-aqueous precursor composition of claim 1 , wherein a and b are both 1 and c is 1 or 2.
9. The non-aqueous precursor composition of claim 1 , comprising two or more different silver complexes, each represented by formula (I).
10. The non-aqueous precursor composition of claim 1 , having long term stability such that, when it is held at ambient temperature and under yellow safelight for 24 hours, less than 0.1 mol % of its original silver ion content is reduced to silver metal.
11. The non-aqueous precursor composition of claim 1 , comprising no more than 5 weight % based on the total weight of the hydroxy-free, nitrile-containing aprotic solvent.