Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
2001-09-17
2003-02-25
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C428S413000, C428S414000, C428S320200, C428S3550EN, C428S473500, C156S330000, C156S331700, C525S452000, C525S528000, C525S540000
Reexamination Certificate
active
06524711
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a thermosetting resin composition, as well as to a resin coated metal foil, a prepreg and a film-shaped adhesive all using the above composition, suitably used particularly in electric and electronic fields.
(2) Description of the Prior Art
In printed wiring boards widely used in high-frequency devices, computers, etc. employed in electric or electronic appliances and communication, the wiring density is becoming finer and the signal processing speed is becoming higher. In connection therewith, the insulating resin constituting the laminate is strongly desired to have higher heat resistance and a lower dielectric constant. Meanwhile, the printed substrate used in the printed wiring board is ordinarily produced by impregnating an insulating resin into a base material such as a glass cloth (this sheet-like material is called a prepreg) and hot-pressing several sheets of the prepreg. Further, for production of a multilayer printed wiring board, a build-up process has been developed in recent years. In this build-up process, a resin coated metal foil (the metal foil is a copper foil in many cases) is used. The insulating resin used in such applications is required to have high heat resistance, a low dielectric constant, a low dielectric loss tangent, a high adhesion strength, a low water absorption, etc. in good balance.
As the insulating resins heretofore used in electric or electronic material fields, there are mentioned an epoxy resin, a polyimide resin, a phenolic resin, a BT (bismaleimide triazine) resin, etc. For example, a thermosetting resin composition comprising an epoxy resin, an amine type curing agent or an acid anhydride type curing agent and, as necessary, a curing accelerator has been used in production of a prepreg by impregnation into a base material such as a glass cloth and subsequent curing up to a B-stage, or in production of a resin coated metal foil having thereon a resin layer formed by the thermosetting resin composition, used for lamination on a circuit pattern-printed inner layer substrate for production of a multilayer printed wiring board (see, for example, JP-A-9-232763).
Epoxy resins have been used most generally from the standpoint such as overall balance of cost and properties. However, they are unable to respond to the higher requirements for resin properties, associated with the movement of electric or electronic appliances in recent years toward smaller size and higher wiring density; further, in producing therewith a prepreg, a resin coated metal foil, a film-shaped adhesive, etc., they have had, in the B-stage, operational problems such as remaining of resin tack, detaching of resin powder, resin cracking and the like. BT resins have had problems in, for example, high water absorption and inferior adhesivity to metals. Polyimide resins have had problems of, for example, requiring a high temperature during molding.
SUMMARY OF THE INVENTION
The present invention aims at alleviating the above-mentioned problems of the prior art and providing mainly a thermosetting resin composition which is, in a semi-cured state (a B-stage), free from resin cracking or resin powder detaching when bent and therefore easy to handle and, after curing, has good electrical properties and heat resistance.
The present inventors had made an intensive study in order to alleviate the problems possessed by conventional thermosetting resin compositions. As a result, the present inventors had developed a thermosetting resin composition composed mainly of a polycarbodiimide and an epoxy resin, having excellent heat resistance and adhesivity, and a patent application had been filed therefor. The present inventors made a further study in order to provide a thermosetting resin composition of higher properties useful particularly in electric and electronic fields. As a result, the present invention has been completed.
The present invention provides the following inventions to accomplish the above aims.
[1] A thermosetting resin composition comprising:
a polycarbodiimide obtained from organic polyisocyanates containing at least one kind of aromatic polyisocyanate,
an epoxy resin,
a curing agent for epoxy resin, and
a rubber component,
wherein the proportions of the individual components are 100 parts by weight of the polycarbodiimide, 30 to 150 parts by weight of the epoxy resin, 1.0 equivalent or less, relative to the epoxy resin, of the curing agent for epoxy resin, and 0.1 to 20 parts by weight of the rubber component.
[2] A resin coated metal foil which is a metal foil having thereon a resin layer formed by semi-curing a thermosetting resin composition set forth in the above [1].
[3] A prepreg obtained by impregnating a base material with a thermosetting resin composition set forth in the above [1].
[4] A film-shaped adhesive obtained by dissolving a thermosetting resin composition set forth in the above [1], in a solvent and casting the resulting solution.
[5] A film-shaped sealant obtained by dissolving a thermosetting resin composition set forth in the above [1], in a solvent and casting the resulting solution.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
As described above, the thermosetting resin composition of the present invention comprises:
a polycarbodiimide obtained from organic polyisocyanates containing at least one kind of aromatic polyisocyanate,
an epoxy resin,
a curing agent for epoxy resin, and
a rubber component.
As the polycarbodiimide used in the present invention, there can be mentioned those polycarbodiimides which can be produced, for example, by a process disclosed in JP-A-51-61599, a process by L. M. Alberin et al. [J. Appl. Polym. Sci., 21, 1999 (1977)], or a process disclosed in JP-A-2-292316, etc., that is, those polycarbodiimides which can be produced form an organic polyisocyanate in the presence of a catalyst capable of promoting the carbodiimidization of isocyanate. These polycarbodiimides can be used singly or in admixture.
As the organic polyisocyanate used as a raw material for synthesis of polycarbodiimide in each of the above processes, there can be mentioned, for example, aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and mixtures thereof. Specifically, there can be mentioned 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, crude tolylene diisocyanate, crude methylene diphenyl diisocyanate, 4,4′,4″-triphenylmethylene triisocyanate, xylylene diisocyanate, m-phenylene diisocyanate, naphthylene-1,5-diisocyanate, 4,4′-biphenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-biphenyl diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′diisocyanate, tetramethylxylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, etc., and mixtures thereof.
At least one kind of the organic polyisocyanates which are a raw material for synthesis of the polycarbodiimide used in the present invention, must be an aromatic polyisocyanate capable of giving a polycarbodiimide having a film-formability, because the thermosetting resin composition of the present invention obtained with the polycarbodiimide needs to be able to become a film after semi-curing or curing. As a particularly preferable example of such an aromatic polyisocyanate, 4,4′-diphenylmethane diisocyanate can be mentioned. Herein, “aromatic polyisocyanate” refers to an isocyanate having, in the molecule, at least two isocyanate groups directly bonding to the aromatic ring.
The aromatic polyisocyanate can be used in such an amount that the thermosetting resin composition of the present invention shows no tack in a semi-cured state (a B-stage). The aromatic polyisocyanate is preferably contained in the organic polyisocyanates used, specificall
Imashiro Yasuo
Ito Takahiko
Nakamura Norimasa
Tomita Hideshi
Dawson Robert
Feely Michael J
Kubovick & Kubovcik
Nisshinbo Industries Inc.
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