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
2001-06-22
2004-06-01
Woodward, Ana (Department: 1711)
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...
C525S432000
Reexamination Certificate
active
06743849
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermoplastic resin composition high in mechanical strength, excellent in moldability and friction property (sliding wear resistance) and moreover high in anti-blister property at a high temperature, for example, in the case where soldering is conducted in a reflowing oven.
2. Description of the Background Art
Polyamide 4,6 (nylon 4,6) resins are high in mechanical strength such as modulus in flexure and tensile elongation and excellent in thermal properties such as heat resistance, electrical properties, friction property and molding and processing ability and are hence utilized in wide fields such as electric and electronic parts, vehicle parts, various instruments, and sundries.
With the miniaturization of products and the improvement in productivity in recent years, the field of electric and electronic industries have come to adopt a method of soldering resinous electronic parts having resin-made parts such as connectors, switches, relays and coil bobbins to a printed board by a surface-mount technology system.
The term “surface-mount technology system” as used herein means a mounting system that electronic parts are placed on a printed wiring board through a creamy solder, and the wiring board is then passed through a heating oven (reflowing oven), thereby melting the solder to fix the electronic parts to the wiring board. This surface-mount technology system is different from the conventional insertion-mount system (lead-through system) that lead wires of electronic parts are inserted into through-holes in a wiring board, and soldering (free soldering or wave soldering) is directly conducted on a surface opposite to a surface on which the electronic parts are to be mounted.
This surface-mount technology system has such merits that mount density can be heightened, mounting can be conducted on both surfaces of a board, and production cost can be reduced by high efficiency and is becoming the mainstream of the mount system by soldering.
When electronic parts composed of the conventionally known resin materials including polyamide 4,6 resins are fixed (soldered) to a wiring board by means of the surface-mount technology system, however, such a system involves a problem that blister occurs on the surfaces of the electronic parts when the wiring board, on which the electronic parts have been placed, passes through a reflowing oven, and the commercial value of the resulting product is markedly reduced.
In addition, there is a tendency for frequency of occurrence of blister to increase with the increased oven temperature (set temperature) required for use of a lead free solder which is favorable from the viewpoint of environmental protection and the like.
Therefore, it is desired to develop a resin composition, which is excellent in anti-blister property when soldering is conducted in a reflowing oven, as a resin material forming resinous electronic parts subjected to the surface-mount technology system.
On the other hand, polyamide resins (hereinafter may also be referred to as “polyamide 9, T resins) obtained by polycondensing 1,9-nonanediamine and terephthalic acid have high mechanical strength (tensile strength and flexural strength) and good heat resistance, and are hence considered to be capable of developing good anti-blister property and expected to be developed into use for the surface-mount technology system.
However, the polyamide 9, T resins are poor in moldability, and so it is difficult to produce thin-wall moldings and the like therefrom. In addition, the polyamide 9, T resins involve a problem that the tensile elongation and the strength of a weld part are poor, and moreover the friction property is also poor.
SUMMARY OF THE INVENTION
The present invention has been made on the basis of the foregoing circumstances.
It is the first object of the present invention to provide a thermoplastic resin composition having excellent anti-blister property, which does not cause blister on the surfaces of resinous parts by passing through a reflowing oven when the resin composition is used as a resin material forming the resinous parts subjected to the surface-mount technology system.
A second object of the present invention is to provide a thermoplastic resin composition high in mechanical strength such as flexural strength, weld strength and tensile elongation and excellent in moldability and friction property.
The present inventors have carried out an extensive investigation with a view toward achieving the above objects. As a result, it has been found that a polyamide 4,6 resin and a polyamide 9, T resin are blended with each other in respective specific proportions, thereby providing a thermoplastic resin composition high in mechanical strength (flexural strength, weld strength and tensile elongation) and excellent in moldability, friction property and anti-blister property. The present invention has been led to completion on the basis of such a finding.
In particular, it has been surprising that the modulus in flexure of the thermoplastic resin composition according to the present invention becomes higher than a value calculated from the blending ratio of the polyamide 4,6 resin to the polyamide 9, T resin.
According to the present invention, there is thus provided a thermoplastic resin composition comprising a polyamide resin component (hereinafter may also be referred to as “specific polyamide resin component”) composed of 5 to 95% by weight of the following component (A) and 95 to 5% by weight of the following component (B):
Component (A): a polyamide resin obtained by polycondensing diamine(s) including at least tetramethylenediamine with dicarboxylic acid(s) including at least adipic acid; and
Component (B): a polyamide resin obtained by polycondensing diamine(s) including at least one of 1,9-nonanediamine and 2-methyl-1,8-octanediamine with dicarboxylic acid(s) including at least terephthalic acid.
In the thermoplastic resin composition according to the present invention, the specific polyamide resin component may preferably be composed of 55 to 80% by weight of the component (A) and 45 to 20% by weight of the component (B).
In the thermoplastic resin composition according to the present invention, the component (A) may preferably be composed of a polyamide 4,6 resin obtained from tetramethylenediamine and adipic acid.
In the thermoplastic resin composition according to the present invention, the component (B) may be preferably be composed of a polyamide resin obtained from 1,9-nonanediamine and/or 2-methyl-1,8-octanediamine, and terephthalic acid.
The thermoplastic resin composition according to the present invention may preferably comprise, per 100 parts by weight of the specific polyamide resin component, 5 to 70 parts by weight of (C) a flame retardant (hereinafter may also be referred to as “component (C)) and 0 to 50 parts by weight of (D) a flame-retardant aid (hereinafter may also be referred to as “component (D)).
The thermoplastic resin composition according to the present invention may preferably comprise, per 100 parts by weight of the specific polyamide resin component, 5 to 300 parts by weight of (E) an inorganic filler (hereinafter may also be referred to as “component (E)).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The thermoplastic resin compositions according to the present invention will hereinafter be described in detail.
Component (A)
The component (A) constituting the thermoplastic resin composition according to the present invention is a polyamide resin obtained by polycondensing diamine(s) including at least tetramethylenediamine with dicarboxylic acid(s) including at least adipic acid and includes (i) “a polyamide 4,6 resin” obtained by polycondensing tetramethylenediamine with adipic acid and (ii) “a copolyamide” comprising a polytetramethylene adipamide unit as a main constitutive component.
No particular limitation is imposed on the preparation process of the component (A). As examples thereof, may be mentioned the processes described in Jap
Mawatari Masaaki
Mitamura Kenji
DSM JSR Engineering Plastics Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Woodward Ana
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