Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1999-02-11
2001-03-27
Berman, Susan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S028000, C522S029000, C522S037000, C522S048000, C522S053000, C522S025000, C522S027000, C522S064000, C522S106000, C522S107000, C522S100000, C522S101000, C522S102000, C522S081000, C526S090000, C526S123100, C526S124200, C526S131000, C526S134000, C526S196000, C526S204000, C526S217000
Reexamination Certificate
active
06207726
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photocurable prepreg composition which comprises a resin, and a fiber-reinforcing material and/or a filler and which assumes various forms such as a roll, pipe, or tube, as well as to a production method therefor.
BACKGROUND OF THE INVENTION
With regard to fiber-reinforced plastics (hereinafter referred to as FRP) which are used as materials that require strength such as molded products and structural materials for buildings, thermosetting resins such as epoxy resins, unsaturated polyester resins, and vinyl ester resins (also called epoxy acrylate resins) are used in combination with inorganic or organic reinforcing materials such as glass fiber or carbon fiber.
Conventionally, prepreg sheets employing a thermosetting resin have been produced by impregnating a fibrous substrate such as glass fiber or carbon fiber with a thermosetting resin containing a non-reactive solvent as a diluent, and simultaneously drying to remove the non-reactive solvent and B-staging the thermosetting resin (thickening) by, e.g., heating; or by impregnating a fibrous substrate such as glass fiber or carbon fiber with a solvent-free thermosetting resin and B-staging by, e.g., heating. Among these prepregs, those of photocurable types have been used particularly for the production of large-size prepregs which cannot be heated or are difficult to heat homogeneously, or for the production of prepregs which are used outdoors. The photocurable-type prepregs have thus become of interest in that they have high curing speed and may simply be applied to buildings without use of any heat source.
There is known a method for B-staging a thermosetting resin in order to produce prepregs wherein a starting thermosetting resin is partially cured to attain an appropriate B stage at which the polymerization is terminated. However, a stable B-stage is difficult to maintain during typical production steps. In particular, when a resin containing a compound having a radical-polymerizable unsaturated group such as an unsaturated polyester resin or vinyl ester resin is B-staged by prepolymerizing the radical-polymerizable unsaturated groups, a stable B stage is difficult to maintain.
In this connection, there is known a method for thickening a vinyl ester resin wherein a hydroxyl group or a carboxyl group pendant from a hydroxyl group in the vinyl ester resin is caused to react with a diisocyanate to attain a B stage. However, using the method for providing a stable B stage is difficult, since the B-staging reaction is largely susceptible to a microamounts of water, active groups, etc.
With regard to typical methods for thickening a unsaturated polyester resin, there are methods involving addition of magnesium oxide which are disclosed in JP-A-62-73914, JP-A-62-73915, JP-A-62-73916, and JP-A-62-73917 (The term “JP-A” as used herein means an “unexamined published Japanese patent application.”).
However, the above-described methods for thickening that employ a diisocyanate and magnesium oxide involve a problem that a reactive diluent such as styrene monomer present in a resin does not participate in thickening reaction of a vinyl ester resin or unsaturated polyester resin, to thereby result in separation and sagging of the reactive diluent during storage of the prepreg.
JP-A-6-287524 discloses a method in which a gelling agent is added to a raw material of a prepreg to make the material a disintegrable gel. In the method, however, controlling transition of a gel state to a B stage is still difficult. Thus, problems related to B-staging an unsaturated polyester resin or vinyl ester resin remain unsolved.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a photocurable prepreg composition with easy control of a B stage state of a thermosetting resin such as an unsaturated polyester resin or a vinyl ester resin and realization of a stable B stage state; which provides a prepreg composition having excellent storage stability; and which has a wide range of usability, i.e., molded products having good curability and available in a variety of forms such as a sheet, roll, tube, or pipe, structural materials for buildings, or mending materials thereof.
Another object of the present invention is to provide a production method therefor.
The above objects of the present invention have been accomplished by provision of the following:
(1) a photocurable prepreg composition which comprises an unsaturated polyester resin and/or a vinyl ester resin; at least two photopolymerization initiators with photosensitivity in different wavelength ranges; and an inorganic or an organic fiber-reinforcing material and/or filler, and which composition is treated with light of a specific wavelength such that at least one photopolymerization initiator and radical-polymerizable unsaturated groups remain partially in said resin;
(2) a photocurable prepreg composition according to (1), wherein the photopolymerization initiators comprise a combination of a photopolymerization initiator with photosensitivity in near infrared range and a photopolymerization initiator with photosensitivity in visible and/or ultraviolet range;
(3) a photocurable prepreg composition according to (1), wherein the photopolymerization initiators comprise a combination of a photopolymerization initiator having photosensitivity in a visible range of wavelengths of 500 nm or more and a photopolymerization initiator with photosensitivity in a visible range of wavelengths of less than 500 nm and/or in ultraviolet range;
(4) a photocurable prepreg composition according to (2) or (3), wherein the photopolymerization initiator with photosensitivity in a visible range of wavelengths of 500 nm or more or in near infrared range comprises a combination of a cationic dye represented by formula (1):
D
+
&Circlesolid;A
−
(1)
(wherein D
+
represents a dye cation which is photosensitive in the visible or near infrared range and which is derived from methine, polymethine, cyanine, xanthene, oxazine, thiazine, arylmethane, and pyrylium; and A
−
represents an anion) and an organo borate represented by formula (2):
wherein Z
+
represents a cation; each of R
1
, R
2
, R
3
, and R
4
represents an alkyl group, an aryl group, an acyl group, an aralkyl group, an alkenyl group, an alkynyl group, a silyl group, a heterocyclic group, or a halogen atom;
(5) a photocurable prepreg composition according to (4), wherein a cation moiety (D
+
) of the photopolymerization initiator represented by formula (1) and with photosensitivity in a visible range of wavelengths of 500 nm or more or in the near infrared range is a cyanine or a triarylmethane cationic dye;
(6) a photocurable prepreg composition according to any of (1) to (5), wherein one of the photopolymerization initiators with photosensitivity in the visible range and/or ultraviolet range comprises an acylphosphine oxide compound or a combination of a hexaarylbisimidazole compound and a hydrogen-donating compound;
(7) a production method for a photocurable prepreg composition comprising a step of prepolymerization by irradiating a composition which comprises an unsaturated polyester resin and/or a vinyl ester resin; at least two photopolymerization initiators with photosensitivity in different wavelength ranges; and an inorganic or an organic fiber-reinforcing material and/or filler, with light of a wavelength in a range where at least one of the photopolymerization initiators present in the composition has photosensitivity and where at least one of the other photopolymerization initiators is without photosensitivity;
(8) a production method for a photocurable prepreg composition according to (7), which comprises a step of prepolymerization by irradiating a composition which comprises an unsaturated polyester resin and/or a vinyl ester resin; at least two photopolymerization initiators with photosensitivity in different wavelength ranges; and an inorganic or an organic fiber-reinforcing material and/or filler, with visible light of a w
Kamata Hirotoshi
Ohtani Kazuo
Sendai Hidetake
Sugita Shuichi
Watanabe Takeo
Berman Susan W.
Showa Denko Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
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