Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-12-13
2004-02-24
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S032000, C522S064000, C522S065000, C522S066000, C522S100000, C522S170000, C522S181000, C522S168000
Reexamination Certificate
active
06696506
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a cationic photocatalyst composition and a photocurable composition incorporating the cationic photocatalyst composition. More particularly, the present invention relates to a cationic photocatalyst composition and a photocurable composition which can assure a sufficient open time after irradiation and enhance adhesive strength after cure.
BACKGROUND ART
Aryl diazonium, triaryl sulfonium, diaryl iodonium, benzyl sulfonium and phosphonium salts are conventionally known as cationic photocatalysts which polymerize or cure compounds containing an epoxy or other cationically polymerizable group. These cationic photocatalysts are used in combination with compounds containing cationically polymerizable groups, such as epoxy resins, oxetane derivatives and vinyl ether derivatives, to provide compositions useful for photopolymerization or photocure.
A variety of industrial uses have been investigated for the aforementioned compositions utilizing a photocure reaction, including paints, coatings, varnishes, matrices for composite materials, materials for giving light-developed forms, adhesives and pressure-sensitive adhesives. Particularly, the application of epoxy resins on such various uses has been investigated because they, when cured, show excellent adhesion, creep resistance, light stability, heat stability, chemical stability and the like (“Newly-revised Epoxy Resin”, Hiroshi Kakiuchi, Shoko-do, 1985).
In order for compositions to be useful for the above-described purposes, they when cured must show good adhesion to an adherend and good light stability. In addition, they must have the ability to cure quickly when cationically photopolymerized, i.e., fast-curing property. Where they are formulated into paints, coatings or varnishes, curing thereof is desired to complete as soon as irradiation is terminated. That is, it is strongly demanded that curing thereof completes quickly within a short exposure time.
Adhesives and pressure-sensitive adhesives utilizing cationic photopolymerization have been also noted. Such adhesives, when cured via cationic photopolymerization, show excellent levels of creep resistance, light stability, water resistance, heat stability and chemical stability and high adhesive strength. In addition, they show good adhesion to various materials such as metals, plastics and glasses. Adhesives, pressure-sensitive adhesives or the like have been thus proposed which utilize cationic photocure of cationically photopolymerizable compounds such as epoxy resins.
When in use for joining adherends, such adhesives, pressure-sensitive adhesives or the like are required to show fast-curing characteristics as required for paints, coatings and varnishes, and to simultaneously provide a sufficiently long work time (a period of time which permits a joint operation after they are irradiated, also referred to as an open time) to permit a joint operation. That is, it is strongly demanded that they remain sufficiently flowable, wet and tacky to permit a joint operation after they have been irradiated.
In Japanese Patent Laying-Open No. Sho 63-248825, slow-curing type UV-curable epoxy resins are disclosed utilizing a fixing agent containing a poly(alkylene oxide) residue portion. The use of fixing agent containing a poly(alkylene oxide) residue portion reduces the occurrence of skinning after exposure to an ultraviolet ray. The skinning refers to a condition wherein a skin layer is caused to cure by irradiation to reduce its wettability, tackiness and the like while an interior maintains its flowability.
In accordance with the teaching of Japanese Patent Laying-Open No. Sho 63-248825, the occurrence of skinning is successfully retarded by the use of fixing agent containing a poly(alkylene oxide) residue portion. However, since this reference contemplates to satisfy the skinning-preventive property and adhesive property simultaneously by the use of such a fixing agent. It has been accordingly difficult to design such properties independently.
Japanese Patent Laying-Open No. Hei 3-172378 discloses photocurable epoxy adhesive compositions which contain an epoxide cure retarder selected from the group consisting of nitrile- or vinyl ether-substituted organic materials. The to use of vinyl ether-substituted organic materials is reported to assure an open time of about 40 minutes. Japanese Patent Laying-Open No. Hei 3-172378 discloses photocurable epoxy adhesive compositions with an extended open time. No reference is however made as to the adhesive property, i.e., adhesive strength of such adhesive compositions.
In view of the current state of the art as described above, it is an object of the present invention to provide a cationic photocatalyst composition and a photocurable composition incorporating the cationic photocatalyst composition which are suitable for use in adhesives or pressure-sensitive adhesives utilizing cationic photopolymerization, which can present a sufficiently long open time after they are irradiated and which, when cured, provide a sufficiently high adhesive strength.
DISCLOSURE OF THE INVENTION
In accordance with a broad aspect of the present invention, a cationic photocatalyst composition is provided which is characterized as containing a photosensitive onium salt and a compound either represented by the following formula (1) or having a substituting group represented by the following formula (1).
Formula (1) [Compound B]
In the formula (1), R and R′ are suitably selected from hydrogen, halogen, saturated hydrocarbon groups, unsaturated hydrocarbon groups, substituting groups comprised of any suitable combination of elements such as carbon, hydrogen, oxygen, nitrogen and sulfur, and the like. l and n each is an integer of 2 or larger.
In accordance with another broad aspect of the present invention, a photocurable composition is provided which is characterized as containing the above-specified cationic photocatalyst composition and a compound having at least one cationically polymerizable group in a molecule.
In the present invention, a preferred cationically polymerizable group is an epoxy group.
A detailed description of the present invention is below given.
The cationic photocatalyst composition in accordance with the present invention contains the above-specified photosensitive onium salt which shows excellent cationic photocatalytic activity, and a compound either represented by the formula (1) or containing, as a substituting group, a structure of the formula (1).
Examples of onium salts include, but not limited to, aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts and the like. The use of photosensitive onium salts which exhibit low thermal catalytic activities in the approximate temperature range of 20-80° C. is preferred for their ability to increase the storage stability of the composition.
Specific examples of photosensitive onium salts include IRGACURE 261 (product of Ciba-Geigy), OPTOMER SP-150 (product of Asahi Denka Ind. Co., Ltd.), OPTOMER SP-151 (product of Asahi Denka Ind. Co., Ltd.), OPTOMER SP-170 (product of Asahi Denka Ind. Co., Ltd.), OPTOMER SP-171 (product of Asahi Denka Ind. Co., Ltd.), UVE 1014 (product of General Electronics Co., Ltd.), CD 1012 (product of Sartomer), SANAID SI-60L (product of Sanshin Chem. Ind. Co., Ltd.), SANAID SI-80L (product of Sanshin Chem. Ind. Co., Ltd.), SANAID SI-10L (product of Sanshin Chem. Ind. Co., Ltd.), CI-2064 (product of Nippon Soda Co., Ltd.), CI-2639 (product of Nippon Soda Co., Ltd.), CI-2624 (product of Nippon Soda Co., Ltd.), CI-2481 (product of Nippon Soda Co., Ltd.), RHODORSIL PHOTOINITIATOR 2074 (product of Rhone Poulenc GmbH), UVI-6990 (product of Union Carbide), BBI-103 (product of Midori Chem. Co., Ltd.), MPI-103 (product of Midori Chem. Co., Ltd.), TPS-103 (product of Midori Chem. Co., Ltd.), MDS-103 (product of Midori Chem. Co., Ltd.), DTS-103 (product of Midori Chem. Co., Ltd.), NAT-103 (product of Midori Chem. Co., Ltd.), NDS-103 (product of Midori Chem. Co., Ltd.) and the like.
The above-listed
McClendon Sanza L.
Seidleck James J.
Sekisui Chemical Co. Ltd.
Townsend & Banta
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