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
1999-05-06
2001-11-13
Seidleck, James J. (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...
C492S055000
Reexamination Certificate
active
06316536
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin composition comprising a polyarylene sulfide (hereinafter referred to as PAS) and an inorganic filler, and to moldings and connectors made of it. More precisely, the invention relates to a resin composition comprising PAS and an inorganic filler, of which the moldings are burred little and which has high weld strength and good flow moldability, and also to moldings and connectors made of the composition.
2. Description of the Related Art
PAS is known as an engineering plastic with high mechanical strength, good heat resistance and good chemical resistance, and moldings of a resin composition as prepared by mixing and kneading PAS and an inorganic filler have many applications in various fields.
However, it has heretofore been said that the resin composition is defective in that its moldings are burred.
Various methods have been proposed for reducing the burrs around the moldings of the composition. For example, one method comprises thermally crosslinking the resin to thereby introduce many branches into the resin. The method could reduce the burrs around the moldings of the resin composition, but the mechanical properties of the moldings are lowered and the resin composition would produce gas when decomposed (see JP-A 64-9266).
In order to compensate for the defect of the thermally-crosslinked PAS, a branched PAS has been proposed, which is prepared by adding a branching agent such as trichlorobenzene or the like to the reaction system followed by polycondensing the resulting system (see JP-A 51-144497). The strength of the branched PAS could be higher than that of the thermally-crosslinked PAS, but is lower than that of a linear PAS. Therefore, one often hesitates in using the branched PAS in the field of resin moldings that are required to have few burrs and have high strength.
Another branched PAS has been proposed, for which a branching agent is added to the reaction system within a period of about 75 minutes before the completion of polycondensation to give a branched PAS (see JP-A 55-28217), but this is faced with the same problem as above.
Still other techniques have been proposed of compounding PAS with any other resin into composites (see JP-A 4-213357, etc.), or copolymerizing PAS (see JP-A 8-134352, etc.), or modifying PAS (see JP-A 5-170908, etc.). However, these could not still satisfy the requirements of reducing the burrs around the resin moldings and of increasing the mechanical strength of the resin moldings.
In addition to their drawback of giving burrs around their moldings, the resin compositions noted above are further problematic in that their weld strength is low and their fluidity is poor. Therefore, it is desired to solve the problems with those resin compositions.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the problems noted above, and its object is to provide a resin composition comprising PAS and an inorganic filler, of which the moldings are burred little and which has high weld strength and good flow moldability, and also to provide moldings and connectors made of the composition.
We, the present inventors have assiduously studied the problems noted above, and, as a result, have found out a resin composition comprising PAS and an inorganic filler, of which the moldings are burred little and which has high weld strength and good flow moldability. On the basis of this finding, we have completed the present invention.
Specifically, the invention provides a resin composition comprising PAS and an inorganic filler, and moldings and connectors made of it, which are mentioned below.
1. A polyarylene sulfide resin composition comprising (A) from 20 to 90% by weight of a polyarylene sulfide and (B) from 10 to 80% by weight of an inorganic filler, which is characterized in that its burrs are on the level of at most 120 &mgr;m, that it has a weld strength of at least 50 MPa and that the length of its spiral flow having a thickness of 1 mm is at least 100 mm.
2. The polyarylene sulfide resin composition of the above 1, wherein the polyarylene sulfide (A) satisfies the following formulae (1) to (4):
N≧0.3×log
10
(&eegr;
m
)+0.5 (1)
N≧1.10 (2)
F≧57×log
10
(&eegr;
m
)−60 (3)
F≧40 (4)
where N indicates an index to the degree of branching of the polyarylene sulfide, &eegr;
m
indicates the melt viscosity (unit: Pa·s) of the polyarylene sulfide, and F indicates the flexural strength (unit: MPa) of the polyarylene sulfide.
3. The polyarylene sulfide resin composition of the above 1 or 2, wherein the melt viscosity &eegr;
m
of the polyarylene sulfide (A) falls between 20 and 1500 Pa·s.
4. The polyarylene sulfide resin composition of any one of the above 1 to 3, wherein the inorganic filler is of glass fibers.
5. A molding made of the polyarylene sulfide resin composition of any one of the above 1 to 4.
6. A connector made of the polyarylene sulfide resin composition of any one of the above 1 to 4.
7. A polyarylene sulfide resin (A) to be used in the polyarylene sulfide resin composition of the above 1, which satisfies the following formulae (1) to (4):
N≧0.3×log
10
(&eegr;
m
)+0.5 (1)
N≧1.10 (2)
F≧57×log
10
(&eegr;
m
)−60 (3)
F≧40 (4)
wherein N indicates an index to the degree of branching of the polyarylene sulfide, &eegr;
m
indicates the melt viscosity (unit: Pa·S) of the polyarylene sulfide, and F indicates the flexural strength (unit: MPa) of the polyarylene sulfide.
The burr, the weld strength and the spiral flow length that are referred to herein for the resin composition are as follows:
Burr
When a resin composition is molded in a mold by introducing its melt into the cavity of the mold, the melt may flow out through the gaps in the mold and solidifies to give burrs as integrated with the resulting resin molding around it. Resin compositions giving fewer burrs around its moldings are said to have better moldability. The burrs of a resin composition maybe determined according to the following method (a).
(a) To determine the burrs of a resin composition, used is Nihon Seiko's J50EP (this is a 50-ton injection-molding machine) equipped with a mold for burr determination. The cavity of the mold has a shape for UL combustion test pieces, and its size is 127×12.7×3.18 mm. The mold is provided with gas-discharging holes having a width of 10 &mgr;m at the resin melt flow terminal in the cavity. Concretely, a melt of a resin composition is injected into the cavity at a resin temperature of 320° C. and at a mold temperature of 135° C., and is molded therein, for which the molding condition comprises flow rate control until moldings with no burr are obtained, followed by dwell pressure control (set dwell pressure 20%). In that condition, the resin melt flows out through the holes to form burrs around the moldings, and the length of the burrs is measured. The data are averaged, and the averaged value indicates the degree of the burr of the resin composition tested.
Weld Strength
When a molten resin is molded through injection or extrusion in at least two resin melt flows to be welded into one molding, the welded boundary gives a weld zone. The weld strength indicates the strength at the welded boundary (weld zone) in the molding. Moldings having higher weld strength are said to have better mechanical characteristics. The weld strength may be measured according to the following method (b).
(b) To determine the weld strength of a resin composition, used is Nihon Seiko's J50EP (this is a 50-ton injection-molding machine) equipped with a mold for dumbbell test pieces of ASTM Standard (D-638). Concretely, a melt of a resin composition is injected into the cavity from two gates through the fixed check point for dumbbell test pieces to be formed, at a resin temperature of 320° C. and at a mold temperature of 135° C., and is molded therein, for which the molding condit
Okamoto Masaya
Seki Kenji
Senga Minoru
Suga Koichi
Idemitsu Kosan Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Rajguru U. K.
Seidleck James J.
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