Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-12-01
2002-03-19
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C525S454000, C525S504000, C525S523000, C525S528000
Reexamination Certificate
active
06359036
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a curing agent for epoxy resin.
A curing agent for epoxy resin of the invention can cure epoxy resin in a relatively short curing time at low temperatures in the range of 10° C. and below, especially, about 0° C. The curing agent is useful as, for example, a curing agent of epoxy resin adhesive for outdoor construction.
Epoxy resin is widely used as sealing material, coating composition, adhesive, etc, in a variety of fields such as electricity, electronics, and civil engineering and construction, because a cured product of epoxy resin has excellent electrical insulating properties, moisture proof, heat resistance, soldering resistance, chemical resistance, durability, adhesive property, and mechanical strength.
BACKGROUND ART
Conventionally, the curing of epoxy resin is carried out by adding a curing agent to epoxy resin, followed by heating. As typical representative examples of curing agent, there are, for example, diethylenetriamine, triethylenetetramine, isophoronediamine, diaminodiphenylmethane, diaminodiphenylsulfone, polyamides, dicyandiamide, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, novolac type phenol resin, tertiary amines, imidazoles, and amine complex of boron trifluoride.
Of these curing agents, ones which can cure epoxy resin at room temperature are amine curing agents such as diethylenetriamine, triethylenetetramine, polyamides, and tertiary amines. However, diethylenetriamine and triethylenetetramine require four days for curing, and polyamides and tertiary amines require seven days for curing. It is very difficult for other curing agents to be cured at room temperature, and they generally require a curing temperature of 80 to 200° C. and a curing time of 0.5 to 6 hours.
Meanwhile, an epoxy resin adhesive for outdoor construction is generally used in the field of civil engineering and construction. With a conventional curing agent, however, it is very difficult to cure epoxy resin without heating, as previously described. Even with one capable of curing, it takes an extremely long period of time, namely, four to seven days. Especially, for winter-season execution of works in which the outdoor temperature is often 10° C. and below, it is essential to initiate the curing reaction by heating.
Such characteristic of epoxy resin adhesive prolongs the period of execution of works in civil engineering and construction, which is also one of the causes of interfering with labor saving.
An object of the present invention is to provide a curing agent for epoxy resin which can rapidly cure epoxy resin at low temperatures in the range of near 0° C., especially, under −5 ° C.
DISCLOSURE OF THE INVENTION
The present invention provides a curing agent for epoxy resin which comprises at least one selected from 1-aminopyrrolidine and its salt, as an effective component.
The present invention also provides an epoxy resin cured with the above curing agent for epoxy resin.
The present invention also provides an adhesive composition for civil engineering and construction which contains the above curing agent for epoxy resin.
The present invention also provides an epoxy resin coating composition containing the above curing agent for epoxy resin.
A curing agent for epoxy resin of the invention is capable of curing epoxy resin at low temperatures of 10° C. and below, especially, near 0° C., and, in some instances, at extremely low temperatures in the range of near −20° C. Thus, when an epoxy resin adhesive for outdoor is used, for example, in civil engineering and construction, the adhesive can be cured without applying heat, by adding a curing agent for epoxy resin of the invention. This affords a great merit on working process.
It can be said that a curing agent for epoxy resin of the invention serves as a curing agent having an extremely short curing time, at ordinary temperature or higher, whereas it requires several hours for curing at low temperatures in the range of 10° C. and below, especially about 0° C., thereby having a moderate easy-to-use pot life.
A curing agent for epoxy resin of the invention comprises at least one selected from 1-aminopyrrolidine and its salt, as an effective component. Both 1-aminopyrrolidine and its salt are known compounds, and these are used as an intermediate for preparing chemicals or agricultural chemicals. Examples of the salt of 1-aminopyrrolidine are hydrochloride, sulfate and phosphate. Of these, 1-aminopyrrolidine itself can be used suitably.
Although 1-aminopyrrolidine and its salt can be added directly, in the form of powder, to epoxy resin, these are usually used in the form of an aqueous solution, organic solvent solution, or dispersion. Examples of organic solvent are lower alcohols such as methanol, ethanol and isopropanol; aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane; ethers; polar solvent; and halogenated hydrocarbons. In addition, a solution of water and a suitable organic solvent or dispersion may be used. Of these various forms, an aqueous solution is preferred.
The amount of 1-aminopyrrolidine and its salt to be added to epoxy resin is not specifically limited. It may be suitably selected from a wide range, depending on various conditions such as the kind of epoxy resin, the kind and amount of other additives, the use of a cured product of epoxy resin to be obtained, and the curing conditions (the designed curing time and temperature, curing location, etc.). It is usually about 0.4 to 0.6 mole, preferably about 0.45 to 0.55 mole of 1-aminopyrrolidine or its salt, with respect to a single epoxy group of epoxy resin.
Conventional curing agent and curing accelerator can be added, as required, to a curing agent for epoxy resin of the invention insofar as its preferred characteristic is not impaired. As a curing agent, the same as the mentioned conventional ones are usable, and it is also possible to use dihydrazide compound, melamine, methylolmelamine, resol type compound, etc. As a curing accelerator, there are, for example, tertiary amines such as tri-n-butylamine, benzylmethylamine and 2,4,6-tris-(dimethylaminomethyl)phenol; and imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole. These conventional curing agents and curing accelerators can be used singly or in a combination of at least two of them.
Epoxy resin to which a curing agent for epoxy resin of the invention is applicable is not specifically limited, and it may be hitherto known one. Examples thereof are glycidyl ether type epoxy resin, glycidylamine type epoxy resin, cyclic aliphatic epoxy resin, glycidyl ester resin, heterocyclic epoxy resin, and urethane-modified epoxy resin.
Examples of glycidyl ether type epoxy resin are bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, biphenyl type, naphthalene type, fluorene type, phenol novolac type, cresol novolac type, DPP novolac type, trifunctional type, tris(hydroxyphenyl)methane type, and tetraphenylolethane type epoxy resins.
Examples of glycidylamine type epoxy resin are tetraglycidyldiaminodiphenylmethane, triglycidyl isocyanurate, hydantoin type, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, aminophenol type, aniline type, and toluidine type epoxy resins.
Examples of glycidyl ester type epoxy resin are hexahydrophthalate type and phthalate type epoxy resins.
To epoxy resin to which a curing agent for epoxy resin of the invention is applied, an inorganic filler and reinforcing agent can be added, as required, which have conventionally been added to epoxy resin. As an inorganic filler, any known ones are usable, and there are, for example, silica, fused quartz, calcium carbonate, barium carbonate, barium sulfate, alumina hydrate, alumina, magnesia hydrate, zircon, cordierite, silicon nitride, boron nitride, and aluminum nitride. As a reinforcing agent, any known ones are useable, and there are, for example, inorganic materials such as gl
Furuichi Tomohiro
Ishikawa Keiichiro
Kitajima Takashi
Nabeshima Akihiro
Tomotaki Yoshihisa
Kubovcik & Kubovcik
Otsuka Kagaku Kabushiki Kaisha
LandOfFree
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