Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-06-22
2002-08-13
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S513000, C525S133000, C525S437000, C525S535000
Reexamination Certificate
active
06433071
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an aromatic polysulfone resin composition and a molded article thereof. More specifically, the present invention relates to an aromatic polysulfone resin composition comprising a liquid crystal polyester resin and a molded article thereof.
2. Description of the Related Art
Aromatic polysulfone resins are used in wide variety of fields including electric and electronic materials because of their excellent heat-resistance and mechanical property, and recently, there is a need for improvement in flowability due to requirement for a thin product to be used in small size and light weight.
For improving the flowability of an aromatic polysulfone resin, for example, Japanese Patent Kokoku Publication (JP-B) No. 3-72669 discloses a method for compounding a specific amount of polyphenylene sulfide, and JP-B No.3-45107 disclosed a method for compounding a specific amount of polymer which can form a specific anisotropic melt.
However, in IC sockets having increased amount of pins exemplified by a pin grid array (PGA) and ball grid array (BGA), particularly in burn-in sockets, there has been a problem that conventional aromatic polysulfone resin compositions show insufficient flowability in molding; consequently, the resins can not be completely filled in parts of a mold corresponding to a product and a satisfying product can not be obtained.
The object of the present invention is to solve the above problems and to provide an aromatic polysulfone resin composition which shows excellent flowability in molding without losing excellent mechanical property and heat-resistance, and a molded article thereof.
SUMMARY OF THE INVENTION
The present inventors have intensively studied to solve the above-described problems and found that a resin composition comprising specific amount of a specific liquid crystal polyester resin in a specific aromatic polysulfone resin attains the above-described object, and completed the present invention.
That is, the present invention relates to an aromatic polysulfone resin composition comprising 5 to 50 parts by weight of a liquid crystal polyester resin having a flow temperature as defined below of 250 to 320° C., and 100 parts by weight of an aromatic polysulfone resin having a melt viscosity of less than 500 Pa·s measured at 340° C. and a shear rate of 1000/second:
Flow temperature: a temperature at which the melt viscosity is 4800 Pa·s when a resin being heated at a heating rate of 4° C./min. is extruded by using a capillary rheometer having a nozzle having an internal diameter of 1 mm and a length of 10 mm under a load of 100 kg/cm
2
.
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the aromatic polysulfone resin is a polyarylene compound which comprises an arylene unit, ether bond and sulfone bond as essential three repeating structural units and in which the arylene unit is situated disorderly or orderly together with the ether bond and the sulfone bond.
The aromatic polysulfone resin used in the present invention is an aromatic polysulfone resin having a melt viscosity measured at 340° C. and a shear rate of 1000/second of less than 500 Pa·s. If an aromatic polysulfone resin having such a melt viscosity of 500 Pa·s or more is used, the flowability of the resin composition in molding may not be excellent. The melt viscosity is preferably 200 Pa·s or more, and more preferably 300 Pa·s or more. If the melt viscosity is less than 200 Pa·s, the mechanical strength of the molded article is insufficient sometimes.
As the structural unit of the aromatic polysulfone resin used in the present invention, those represented by the following general formulae (I), (II) and (III) are exemplified.
In the formula (I), R
1
represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 10 carbon atoms, a phenyl group or a halogen atom, p is an integer from 0 to 4. R
1
s on the same or different nuclei may be different from each other. The symbols “p”s may be different from each other.
In the formula (II), R
1
and p are the same as defined in the formula (I).
In the formula (III), R
1
and p are the same as defined in the formula (I). The symbol “q” is an integer from 1 to 3.
When the aromatic polysulfone resin is composed of the above-described structural unit (I), p in (I) is preferably 0. When the aromatic polysulfone resin is composed of the above-described structural units (I) and (II), the molar ratio (I)/(II) is usually from 0.1 to 50, preferably from 0.1 to 9.0. and more preferably from 1.0 to 4.0. Further, when the aromatic polysulfone resin is composed of the above-described structural units (I) and (III), the molar ratio (I)/(III) is usually from 0.1 to 20, preferably from 0.1 to 9.0, and more preferably from 1.0 to 4.0.
Among them, those composed of the above-described structural unit (I) and those composed of the above-described structural units (I) and (II) are preferable, and those composed of the above-described structural unit (I) are further preferable.
As the method for producing the aromatic polysulfone resin used in the present invention, known methods can be adopted. As commercially available aromatic polysulfone resins, examples of those composed of the above-described structural unit (I) include Sumika Excel PES 3600P: trade name, manufactured by Sumitomo Chemical Co, Ltd. The terminal structure thereof is depend upon the methods for producing respective resins, and examples thereof include —Cl, —OH, —OR (R is an alkyl group) and the like.
In the present invention, the liquid crystal polyester resin is a polyester generally called thermotropic liquid crystal polymer, and that which forms an anisotropic melt at a temperature of 400° C. or less is preferable. Specific examples thereof include:
those comprising an aromatic dicarboxylic acid, aromatic diol and aromatic hydroxycarboxylic acid in combination; those comprising different aromatic hydroxycarboxylic acids;
those comprising an aromatic dicarboxylic acid and an aromatic diol in combination;
those obtained by reacting an aromatic hydroxycarboxylic acid with a polyester such as polyethylene terephthalate and the like. Instead of these aromatic dicarboxylic acids, aromatic diols and aromatic hydroxycarboxylic acids, ester-forming derivatives thereof may also be used.
The liquid crystal polyester resin used in the present invention has a flow temperature as defined below of 250 to 320° C., preferably of 270 to 310° C.
Flow temperature: a temperature at which the melt viscosity is 4800 Pa·s when a resin being heated at a heating rate of 4° C./min. is extruded by using a capillary rheometer having a nozzle having an internal diameter of 1 mm and a length of 10 mm under a load of 100 kg/cm
2
.
When a liquid crystal polyester resin having the flow temperature over 320° C. is used, the flowability of the resin composition in flowing may be insufficient, and when a liquid crystal polyester resin having the flow temperature less than 250° C. is used, the blocking of a pellet of the resin composition may be induced, or the heat-resistance of the molded article may decrease.
As the structural unit of the liquid crystal polyester resin used in the present invention, followings are exemplified.
Structural units derived from aromatic hydroxycarboxylic acids:
Structural units derived from aromatic dicarboxylic acids:
Structural units derived from aromatic diols:
In the definition of the above substituents X
1
to X
3
, “H” is a hydrogen atom, “alkyl” is preferably an alkyl group having 1 to 10 carbon atoms, and “aryl” is preferably an aryl group having 6 to 20 carbon atoms.
Among combinations of the above-described structural units:
(A
1
), (B
1
), (B
2
), (C
1
);
(A
1
), (B
1
), (B
2
), (C
2
); and
(A
1
), (B
1
), (B
2
), (C
1
), (C
2
)
are preferable from the standpoints of processability, flowability and heat-resistance of the composition, and the molar ratio [(C
1
)+(C
2
)]/(A
1
) is preferably from 0.2 to 1.0, the molar ratio [(B
1
)+(B
2
)]/[(C
Arai Noriyuki
Nagano Satoshi
LandOfFree
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