Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Noninterengaged fiber-containing paper-free web or sheet...
Reexamination Certificate
2000-06-28
2003-05-06
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Noninterengaged fiber-containing paper-free web or sheet...
C428S301400, C428S413000, C428S414000, C428S416000, C428S418000, C428S457000, C428S460000, C442S023000, C442S043000, C442S045000, C442S058000, C442S233000, C525S534000
Reexamination Certificate
active
06558783
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a curable poly-phenylene ether resin composition, and a cured composition and a cured structure obtainable therefrom by curing (hereinafter, a polyphenylene ether is frequently referred to as a “PPE”). More particularly, the present invention is concerned with a curable polyphenylene ether resin composition comprising: (a) a polyphenylene ether resin; and (b) a compound having a 3,4-dihydro-3-substituted-1,3-benzoxazine skeleton (hereinafter, frequently referred to as a “DSBS compound”), or a mixture of the DSBS compound and a ring-opening polymerization reaction product thereof. The present invention is also concerned with a cured resin composition obtainable by curing the curable PPE resin composition, and a laminate structure obtainable therefrom. The curable PPE resin composition of the present invention exhibits, after cured, excellent chemical resistance, moisture resistance, dimensional stability, dieletric electric characteristics, heat resistance and flame retardancy, so that the curable PPE resin composition can be advantageously used as a dielectric material, an insulating material, a heat-resisting material and the like in the electrical and electronic industries, and also in the space and aircraft industries. Especially, the curable PPE resin composition of the present invention can be advantageously used as a resin composition forming insulating layers, such as substrates for a single-sided printed circuit board, a double-sided printed circuit board, a multi-layer printed circuit board, a flexible printed circuit board and a semi-rigid circuit board, and a substrate for a structure having excellent heat removal characteristics.
2. Prior Art
In recent years, electronic components used in various fields, such as communication, household and industries, have been showing a great tendency toward miniaturization. For the purpose of miniaturization, the electronic components have been required to be mounted with high density packing. Accordingly, it has been strongly desired that materials for the electronic components should be excellent not only in heat resistance, flame retardancy, moisture resistance and dimensional stability, but also in electrical characteristics, such as electrical insulating characteristics and dielectric characteristics. For example, a copper-clad laminate made of a thermocurable resin, such as a phenol resin or an epoxy resin, has been used as a substrate for a printed circuit board. However, such a thermocurable resin used as a material for a copper-clad laminate, although having a good balance of various properties mentioned above, has problems in that the resin exhibits undesirable electrical characteristics. Specifically, such a resin exhibits a high dielectric constant and a high dielectric loss tangent in a high frequency range.
For solving the above-mentioned problems, polyphenylene ether resins have recently been expected to be new materials for electronic components, and various attempts have been made to use polyphenylene ether resins as materials for copper-clad laminates.
For example, Unexamined Japanese Patent Application Laid-Open Specification No. 61-287739 (corresponding to U.S. Pat. No. 5,124,415) discloses a laminate comprising an insulating layer and a metallic foil, wherein the insulating layer is obtained by curing a resin composition comprising a polyphenylene ether, and triallyl isocyanurate and/or triallyl cyanurate. However triallyl isocyanurate and/or triallyl cyanurate, which is used as a crosslinking agent, has neither satisfactory flame retardancy nor satisfactory moisture resistance. Therefore, when the above-mentioned laminate is used as a substrate for a printed circuit board, it is necessary to additionally use a chlorine-containing flame retardant and/or a bromine-containing flame retardant, or an auxiliary flame retardant, such as Sb
2
O
3
, Sb
2
O
5
, or NaSbO
3
.1/4H
2
O, so as to improve the flame retardancy of the laminate. However, it has recently been revealed that the use of halogen-containing flame retardants, such as a chlorine-containing retardant and a bromine-containing flame retardant, has a problem in that the combustion of a material containing a halogen-containing flame retardant is accompanied by the generation of toxic gas. Moreover, for solving the problem of poor moisture resistance, it is required to lower the hygroscopicity of the laminate.
Unexamined Japanese Patent Application Laid-Open Specification Nos. 2-55721 and 2-55722 (corresponding to U.S. Pat. Nos. 4,853,423 and 5,073,605, respectively) disclose thermocurable resin compositions comprising a polyphenylene ether, various epoxy resins and the like. Specifically, Unexamined Japanese Patent Application Laid-Open Specification No. 2-55721 discloses a resin composition comprising: (i) a product obtained by reacting bisphenol glycidyl ether, an epoxidated novolak and brominated bisphenol; (ii) a polyphenylene ether; (iii) a novolak resin; (iv) imidazole and poly-amines; (v) a zinc salt; and (vi) Sb
2
O
5
and the like. Unexamined Japanese Patent Application Laid-Open Specification No. 2-55722 discloses a resin composition comprising: (i) bisphenol glycidyl ether, (ii) an epoxidated novolak and (iii) a bromine-containing polyphenylene ether. These resin compositions disclosed in Unexamined Japanese Patent Application Laid-Open Specification Nos. 2-55721 and 2-55722 respectively contain a combination of a bromine-containing flame retardant and Sb
2
O
5
, and a bromine-containing flame retardant, so that these resin compositions exhibit flame retardancy. However, as mentioned above, a bromine-containing flame retardant has a problem in that the combustion of a material containing a bromine-containing flame retardant is accompanied by the generation of toxic gas.
On the other hand, a compound having a 3,4-dihydro-3-substituted-1,3-benzoxazine skeleton (DSBS compound) is disclosed in each of U.S. Pat. No. 5,152,939 and Unexamined Japanese Patent Application Laid-Open Specification No. 9-157456. Specifically, U.S. Pat. No. 5,152,939 discloses that a DSBS compound is caused by heating to form therein a crosslinked mesh structure by a ring-opening polymerization reaction. Unexamined Japanese Patent Application Laid-Open Specification No. 9-157456 discloses a thermocurable resin composition comprising a compound having a 1,3-benzoxazine ring and an epoxy resin. However, the resin composition has low moisture resistance. Further, since the flame retardancy of the resin composition is given by a halogen moiety introduced into an epoxy resin skeleton in the resin composition, the resin composition is likely to cause an environmental pollution due to the generation of toxic gas, as mentioned above.
SUMMARY OF THE INVENTION
In this situation, the present inventors have made extensive and intensive studies with a view toward developing a curable resin composition which is free from the above-mentioned problems accompanying the conventional curable resin compositions, which has excellent dielectric characteristics inherently possessed by a polyphenylene ether and which is not only inexpensive but also simultaneously exhibits, even after cured, excellent flame retardancy, chemical resistance, moisture resistance, dimensional stability, heat resistance and dielectric characteristics. As a result, it has unexpectedly been found that the desired curable resin composition having not only excellent curability but also excellent flame retardancy, chemical resistance, moisture resistance, dimensional stability, heat resistance and dielectric characteristics can be realized by a curable polyphenylene ether resin composition comprising (a) a specific amount of a polyphenylene ether resin; and (b) a specific amount of a compound having a 3,4-dihydro-3-substituted-1,3-benzoxazine skeleton (DSBS compound), or of a mixture of the DSBS compound and ring-opening polymerization reaction product thereof. Based on this novel finding, the present invention has been completed.
Accord
Kato Akihiro
Kinoshita Shozo
Asahi Kasei Kabushiki Kaisha
Birch & Stewart Kolasch & Birch, LLP
Jackson Monique R.
Thibodeau Paul
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