Patent EP-1454936-A1 (EP)
Inventor: KOUCHI SHINJI
IPC: C08G59/32
Filed: 2002-11-06
Abstract: The present invention relates to an epoxy resin composition for
fiber reinforced composite material comprising the following
components (1) - (3) as essential components, their mixing ratios
meeting the following conditions (I) - (IV), and component (3) being
dissolved homogeneously:
   component (1): epoxy resin that is liquid at room temperature,   component (2): aromatic polyamine that is liquid at room
temperature,   component (3): diaminodiphenylsulfone,   condition (I): The proportion of component (1) relative to the
entire epoxy resin in the composition is 60-100 wt%,   condition (II): The sum of the proportions of components (2) and
(3) relative to the entire polyamine in the composition is 70-100
wt%,   condition (III): The proportion of component (3) relative to the
entire polyamine in the composition is 25-60 wt%, and   condition (IV): The stoichiometric ratio of the entire polyamine
to the entire epoxy resin in the composition is 0.7-1.3.    
     Another embodiment of the invention relates to an epoxy resin
composition for fiber reinforced composite material that contains
at least the following components (4) - (6), forms a cured product
with a theoretical molecular weight between crosslinking points
in the range of 250-350 g/mol, and has an initial viscosity at 80°C
of 1-500 MPa·s:
   (4): aromatic epoxy resin with tri- or higher functionality,   (5): aromatic epoxy resin with di- or higher and lower than
tri-functionality, and   (6): aromatic polyamine,  
the molecular weight between crosslinking points being defined as
the weight of the entire cured epoxy resin divided by the number
of crosslinking points contained in the entire cured epoxy resin.
The invention also relates to an epoxy resin composition for fiber
reinforced composite material that consists of the following
components (7) and (8):   (7) a polyglycidyl ether of phenol aralkyl resin as represented
by the following formula:
 
where R 1 , R 2 , R 3  and R 4  denote a hydrogen atom, an alkyl group having
1-8 carbon atoms, or a halogen atom, and m and n denote an integer
of 1-4 and a real number of 0 or more and less than 1, respectively,
and   (8) polyamine.    
     With the constitution described above, the present invention can
provide a liquid epoxy resin composition for low cost production
of high performance fiber reinforced composite material, that has
a low viscosity at relatively low temperatures, and that after being
cured, the cured product is high in glass transition temperature,
elastic modulus and toughness while being small in the glass
temperature decrease caused by water absorption and also small in
the coefficient of linear expansion; and can provide a method to
produce fiber reinforced composite material therefrom. 
     Fiber reinforced composite material produced according to the
present invention can serve as material for parts of aircraft, 
including main wing, tail, rotor blade, fairing, cowl, and door;
parts of spacecraft, including motor case and main wing; and parts
of space satellite body structure. They can also be used preferably
as material for automobile chassis and railroad vehicle body
structure.