Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
2001-06-25
2003-09-16
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C428S034100, C428S034600, C428S034700, C428S035700, C428S035900, C428S297400, C428S300700, C428S320200, C523S400000, C523S427000, C523S428000, C525S107000
Reexamination Certificate
active
06620510
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a prepreg, which is an intermediate material for providing a fiber-reinforced resin composite material such as roll of a resin reinforced with reinforcing fibers, and the like, and an epoxy resin composition suitable for use as a matrix resin for a prepreg.
In addition, the present invention relates to roll of a resin reinforced with reinforcing fibers which possesses an adequate rigidity; a roll of a resin reinforced with reinforcing fibers which exhibits superior humidity and heat resistance properties; and a roll of a resin reinforced with reinforcing fibers which exhibits an adequate rigidity in addition to superior humidity and heat resistance properties.
The present application is based on the corresponding Japanese Patent Applications (Japanese Patent Application, First Publication No. Hei 10-370506, Japanese Patent Application, First Publication No. Hei 10-370507, and Japanese Patent Application, First Publication No. Hei 11-136441), the disclosures of which are included as a part of the present specification.
BACKGROUND
Fiber-reinforced resin molded articles (FRP) comprising a reinforcing fiber of carbon fiber or the like, and matrix resins of epoxy resins and the like, enjoy wide use ranging from general purpose application, such as in fishing rods, golf club shafts, and the like, to the industrial and aerospace fields, due to their light weight and superior mechanical properties, e.g., rigidity, and the like. There exist several methods for molding these FRP molded articles. When using carbon fiber as a reinforcing fiber, a method which utilizes a so-called “prepreg”, an intermediate material wherein a matrix resin is impregnated in advance into the reinforcing fiber, is most widely employed.
In order to satisfy the high speed requirement for printing machines, paper-making machines, paper processing machines, and the like, in recent years, such FRP molded articles having light weight and high rigidity have seen increasing use as a main material for rolls in such machines, which had been conventionally made of steel or aluminum. In particular, in an ink roll and/or nip roll of a rotary press for newspapers, and the like, FRP rolls coated with rubber are starting to be used.
For roll shells of a nip roll for a rotary press for newspapers, an adequate rigidity to resist the molding pressure during nipping is required. Deterioration in the rigidity of a roll shell affects the deflection of a nip roll. Increases in the deflection of a nip roll create difficulty in adjusting the nip width, due to the generation of wrinkles in the paper and deviations in the nip width. Thus, a steel roll shell has been used in the conventional nip roll. Accordingly, when using an PRP roll for a roll shell of a nip roll, it is necessary to provide a rigidity equivalent to that of a steel roll shell.
In addition, as a method for molding an FRP roll, the filament winding method is conventionally known. However, this method does not allow freedom with respect to the design if the rigidity equivalent to that of a steel roll shell is provided. Furthermore, rubber-coated rolls generally need replacement and re-vulcanization of the rubber when the life of the rubber comes to an end. Vulcanization of rubber is conducted under strict high-temperature and high-humidity conditions, and thus, the material used for this purpose needs to be superior with respect to its humidity and heat resistance properties.
However, FRP molded articles comprising a prepreg material that is generally used in sports equipment, which is cured at 130° C., does not exhibit a sufficient heat resistance. In addition, FRP molded articles comprising mainly multi-functional epoxy resins, which are used for imparting heat resistance, do not exhibit sufficient performance due to their high water absorption rate.
The properties of a matrix resin are affected largely by the composition of its resin composition. Recently, the epoxy resin composition that is most widely used as a prepreg matrix resin is cured at 130° C. and used mainly in sports equipment. This epoxy resin composition mainly comprises a bisphenol A epoxy resin, or a phenol novolak epoxy resin, which is then mixed with a curing agent.
This aforementioned epoxy resin composition exhibits superior, balanced properties with regard to the above-described properties; however, this resin composition cannot be used for purposes requiring a higher heat resistance, since the glass-transition temperature of the cured product obtained by curing the resin composition is usually 150° C. or lower.
On the other hand, the resin composition essentially comprising a multi-functional epoxy resin provides a cured product having a high heat resistance from the curing; however, this resin composition also exhibits unfavorable humidity and heat resistance properties, in general, due to a high moisture absorption rate. In addition, the resin composition comprising this multi-functional epoxy resin as a main component possesses unfavorable handling properties with respect to a prepreg obtained thereof, by means of impregnating the epoxy resin into a reinforcing fiber aggregate, due to strong tacking of the prepreg. Furthermore, the resin tends to flow easily while performing curing/molding of this prepreg, thus leading to an undesirable moldability of the prepreg.
Thus, a prepreg cured at 130° C., used when obtaining fiber-reinforced resin molded articles for general sports equipment, does not produce molded articles with sufficient heat resistance. In addition, the cured-molded articles from a prepreg essentially comprising a multi-functional epoxy resin composition, as a matrix resin, which is used for producing fiber-reinforced resin molded articles for their heat resistance properties, generally exhibit a high water absorption rate. In this manner, they pose problems with respect to humidity and heat resistance when used in a fiber-reinforced resin roll for the aforementioned purpose.
Accordingly, a first object of the present invention is to provide an epoxy resin composition, which can provide a cured product with superior humidity and heat resistance properties; an epoxy resin composition which can provide both a cured product with superior humidity and heat resistance properties, and a prepreg with adequate tacking properties, in addition to favorable handling and molding properties at the time of the curing/molding; and a prepreg which possesses adequate tacking properties, and favorable handling and molding properties at the time of the curing/molding.
In addition, a second object of the present invention is to provide a roll of a resin reinforced with reinforcing fibers that is resistant to the severe high temperature, high humidity conditions, e.g., under the vulcanizing conditions for forming a rubber-coated layer.
In addition, a third object of the present invention is to provide a roll of a resin reinforced with reinforcing fibers that possesses an equivalent rigidity to a steel roll.
Furthermore, the fourth object of the present invention is to provide a roll of a resin reinforced with reinforcing fibers that possesses a rigidity equivalent to that of a steel roll, i.e., resistant to the severe high temperature, high humidity conditions such as under the vulcanizing conditions for forming a rubber-coated layer.
DISCLOSURE OF THE INVENTION
In other words, the epoxy resin composition according to the present invention is characterized in satisfying the following condition (a).
(a) the water absorption rate of a cured resin board formed by means of curing said epoxy resin composition after sitting for 60 hours under a saturated vapor at 150° C. is no greater than 3.5% by weight.
Such an epoxy resin composition is able to exhibit superior humidity and heat resistance properties when cured.
In addition, the epoxy resin composition according to the present invention preferably satisfies the following condition (b).
(b) the ratio (LogG′ after/ LogG′ before) of the rigidity (LogG′ after) at 150° C. of said cured resin
Koba Hisao
Taguchi Masato
Yamaguchi Yutaka
Dawson Robert
Feely Michael J
Mitsubishi Rayon Co. Ltd.
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