Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2000-07-19
2002-04-30
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S060000, C528S065000, C528S045000, C528S085000, C525S124000, C427S117000, C428S364000, C428S423100, C428S901000, C156S331700
Reexamination Certificate
active
06380343
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to thermosetting resin compositions for overcoats of flexible circuits, which are particularly excellent in low shrinkage during curing and flexibility.
2. Prior Art
Formerly, the surface protective films of flexible wiring circuits include, for example, those prepared by cutting polyimide films, called as coverlay films, using a die made corresponding to the pattern, which are then adhered onto a substrate with an adhesive; and those prepared by applying a ultraviolet rays-curable or thermosetting overcoat composition the film from which is imparted with flexibility, according to the screen printing method, the latter being more advantageous in workability.
As such curable overcoats, resin compositions mainly consisting of an epoxy resin, an acryl resin, or a mixture thereof have been known. These resins often comprise, as main ingredients, a resin denatured by introducing, particularly, a butadiene or siloxane skeleton, or a long chain fatty skeleton, thereby improving flexibility and preventing warp due to cure shrinkage while trying to avoid reduction of inherent heat resistance, chemical resistance, and electrical insulation.
Recently, however, with lightening and miniaturization of electronic equipment (cameras, 8 mm automatic projectors, portable telephones, personal computers, printers, etc.), flexible substrates have been reduced in thickness and weight, and thus more remarkably affected by flexibility and cure shrinkage of the cured resin composition to be overcoated. Therefore, curing type overcoats do not satisfy requirements for warp upon cure shrinkage and flexibility of the cured products.
[Problems to be solved by the Invention]
In consideration of such points, there have been found no curable resin compositions having properties required of overcoats for flexible circuit such as low shrinkage during curing, and whose cured products have satisfactory properties such as flexibility, adherence, electrical insulation, chemical resistance, heat resistance, etc., and therefore development of such compositions has been expected.
SUMMARY OF THE INVENTION
The present inventors have studied intensively to solve the above problems. As the results, they have attained a group of inventions so linked as to form a single general inventive concept.
A first one of the group of inventions relates to a curable resin composition for overcoat of flexible circuit which comprises a polyol with a number-average molecular weight of 1,000-8,000 and having 2-10 hydroxyl groups per molecule, said polyol being sometimes referred to as “Polyol A” herein, and a polyblock isocyanate, said isocyanate being sometimes referred to as “Isocyanate X” herein; and a curable resin composition for overcoat of flexible circuit which comprises a polybutadiene polyol with a number-average molecular weight of 1,000-8,000 and having 2-10 hydroxyl groups per molecule, said polyol being sometimes referred to as “Polyol Aa” herein, and polybutadiene polyblock isocyanate with a number-average molecular weight of 1,000-8,000 and having 2-10 blockisocyanate groups per molecule, said isocyanate being sometimes referred to as “Isocyanate Xa” herein.
Said invention has been attained based on the findings by the present inventors that curing a urethane resin composition containing, as the main ingredient, a polyol with a number-average molecular weight of 1,000-8,000 and having 2-10 hydroxyl groups (Polyol A) and polyblock isocyanate (Isocyanate X) provides a low shrinkage upon curing, and that a protective film resulting from curing has such satisfactory flexibility, adherence, electric insulation, chemical resistance, heat resistance, and the like properties.
A second one of the group of inventions relates to a curable resin composition for overcoat of flexible circuit which comprises a polyol with a number-average molecular weight of 1,000-8,000 and having 2-10 hydroxyl groups per molecule (Polyol A), a polyol with a number-average molecular weight of 13,000-30,000 and having 2-10 hydroxyl groups per molecule, said polyol being sometimes referred to as “Polyol B” herein, and a polyblock isocyanate (Isocyanate X) as the essential ingredient, wherein the weight ratio (as solid content) of said two polyols is (Polyol A):(Polyol B)=40:60-90:10, and said polyblock isocyanate (Isocyanate X) is in an amount of 0.8-3.5 gram equivalents based on, i.e., per one gram equivalent of, the total hydroxyl groups of the two polyols (Polyol A plus Polyol B); and a curable resin composition for overcoat of flexible circuit which comprises a polyol with a number-average molecular weight of 200-600 and having 2-10 hydroxyl groups per molecule, said polyol being sometimes referred to as “Polyol C” herein, a polyol with a number-average molecular weight of 13,000-30,000 and having 2-10 hydroxyl groups per molecule (Polyol B), and a polyblock isocyanate (Isocyanate X), wherein the weight ratio (as solid content) of the polyols is (Polyol C):(Polyol B)=20:80-50:50 and the polyblock isocyanate (Isocyanate X) is in an amount of 0.8-3.5 gram equivalents based on the total hydroxyl groups of the polyols.
Said invention has been attained based on the findings by the present inventors that mixing a polyol with a number-average molecular weight of 1000-8,000 and having 2-10 hydroxyl groups per molecule (Polyol A) or a polyol with a number-average molecular weight of 200-600 and having 2-10 hydroxyl groups per molecule (Polyol C), and a polyol with a number-average molecular weight of 13,000-30,000 and having 2-10 hydroxyl groups per molecule (Polyol B), and a polyblock isocyanate (Isocyanate X) at a defined ratio provides a low shrinkage upon curing and that a protective film resulting from curing has such satisfactory flexibility, adherence, electric insulation, chemical resistance, heat resistance, and the like properties.
And, a third one of the group of inventions relates to a curable resin composition for overcoat of flexible circuit which comprises, as the essential ingredient, a polybutadiene polyol with a number-average molecular weight of 1,000-8,000 and having 2-10 hydroxyl groups per molecule (Polyol Aa), a polyester polyol with a number-average molecular weight of 13,000-30,000 and having 2-10 hydroxyl groups per molecule, said polyol being sometimes referred to as “Polyol Bb” herein, and a polybutadiene polyblock isocyanate with a number-average molecular weight of 1,000-8,000 and having 2-10 blockisocyanate groups per molecule (Isocyanate Xa), wherein the weight ratio of said polyols (as solid content) is (Polyol Aa) (Polyol Bb)=40:60-90:10 and said polyblock isocyanate (Isocyanate Xa) is in an amount of 0.8-3.5 gram equivalents based on the total hydroxyl groups of the polyols.
Said invention has been attained based on the findings by the present inventors that mixing a polybutadiene polyol with a number-average molecular weight of 1,000-8,000 and having 2-10 hydroxyl groups per molecule (Polyol Aa) and a polyester polyol with a number-average molecular weight of 13,000-30,000 and having 2-10 hydroxyl groups per molecule (Polyol Bb), and a polybutadiene polyblock isocyanate with a number-average molecular weight of 1,000-8,000 and having 2-10 hydroxyl groups per molecule (Isocyanate Xa) at a defined ratio provides a low shrinkage upon curing and that a protective film resulting from curing has such satisfactory flexibility, adherence, electrical insulation, chemical resistance, heat resistance, and the like properties.
DETAILED DESCRIPTION OF THE INVENTION
The group of inventions will be sequentially illustrated in detail below.
Firstly, the first invention will be illustrated in detail.
As for the ingredients of the present curable resin composition for flexible circuit overcoat, the ratio of a polyol with a number-average molecular weight of 1,000-8,000 and having 2-10 hydroxyl groups per molecule (Polyol A) to a polyblock isocyanate (Isocyanate X) is preferably in an amount of 0.8-3.5 gram equivalents of the polyblock i
Orikabe Hiroshi
Yokota Tadahiko
Ajinomoto Co. Inc.
Gorr Rachel
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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