Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1998-10-29
2001-01-09
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
active
06172166
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermally resistant resin composition containing polystyrenes (PS) and polyphenylene oxides (PPO).
2. Prior Art
Resin compositions produced by blending PS with a glass transition point (Tg) of about 100° C. and PPO with Tg of about 210° C. together, have been known widely as one class of thermally resistant polymer alloys in a uniformly miscible system. The PS/PPO resin compositions have single Tg approximately corresponding to the arithmetic mean of the Tgs of the two polymers.
Because PS/PPO resin compositions show excellent electric performance such as dimensional stability, mechanical properties, insulating properties and high-frequency performance, furthermore, the compositions are utilized in resin molded articles such as housings of electric appliances and electronic devices including television sets, air conditioning systems, computer systems; chassis for office appliances for example copying machine and facsimile; various containers (trays and the like); and automobile parts such as instrument panel.
Such PS/PPO resin compositions do not generate hazardous substances such as corrosive gases and dioxin during combustion because the compositions do not contain halogen atoms. In that sense, the compositions are fairly safe. Additionally because PS/PPO resin compositions have excellent thermoplasticity, the compositions can be melt again after the molding process to be put to re-molding process. Thus, PS/PPO resin compositions are considered as recyclable resources. Hence, the utility (applicable range) of PS/PPO resin compositions has been expected to be enlarged from the enhanced need in recent years to preserve the global environment.
The field of the materials for printed board requiring soldering heat resistance (180° C.) is included in one of their applicable range to be enlarged.
Conventional materials for printed board include for example a composite material such as glass epoxy resin-immersed paper and phenol resin-immersed paper, but it is difficult to separate the individual materials constituting these composite materials. Furthermore, the resins used therein are thermosetting. Therefore, these materials are disadvantageous in that reprocessing (recycling) of these materials via melting is substantially impossible while PS/PPO resin compositions can be recycled. Accordingly, it has been desired to use recyclable PS/PPO resin compositions as printed board materials instead of conventional materials for printed board.
However, the glass transition point of conventional PS/PPO resin compositions corresponds to the arithmetic mean of the Tgs of the two polymers, so that a higher content of PS causes lower Tg compared with the Tg of a resin of 100% PPO. Thus, the heat resistance of PS/PPO resin compositions is poorer than that of the resin of PPO alone.
So as to improve the heat resistance of PS/PPO resin compositions, alternatively, it is proposed to improve the glass transition point of the compositions by introducing a sulfonic acid group into either one or both of PS and PPO and reacting sodium methoxide with the sulfone group to form an ionic bond between the polymer chains (Don-Tsai Hseih et al., Polymer, Vol.33, No. 6, 1210 (1992)).
OBJECTS AND SUMMARY OF THE INVENTION
The heat resistance of PS/PPO resin compositions with an ionic bond introduced by reacting a sulfonic acid group with sodium methoxide is still not sufficient. Therefore, further improvement of the heat resistance is desired.
When an acid group such as sulfonic acid group is introduced into either one of PS and PPO, the miscibility of the two may decrease depending on the type and concentration of the acid group. Hence, it is needed to make the two readily miscible irrespective of the type of the acid group and the like.
In addition to these needs, it is also desired to improve the heat resistance of each of PS and PPO.
The present invention is to overcome the problems of prior art. It is an object of the present invention to further improve the heat resistance of PS/PPO resin compositions. Also, it is an object of the present invention to improve the heat resistance of each of PS and PPO. Still furthermore, it is an object of the present invention to make PS readily miscible with PPO.
So as to improve the heat resistance of a thermally resistant resin composition containing PS and PPO, the present inventors have found that the heat resistance of the thermally resistant resin composition can further be improved by introducing an acid group into PS or PPO or both, and neutralizing the acid group with a basic metal compound containing a metal belonging to the group 2B, 3B, 4B or 5B of the periodic table to form an ionic bond. Thus, the invention has been achieved.
More specifically, the present invention is to provide a thermally resistant resin composition containing PS and PPO, wherein at least one of PS and PPO has an acid group and the acid group is neutralized with a basic metal compound containing a metal element of the group 2B, 3B, 4B or 5B of the periodic table.
Furthermore, the present invention is to provide PS with an acid group, wherein the acid group is neutralized with a basic metal compound containing a metal element of the group 2B, 3B, 4B or 5B of the periodic table. Additionally, the present invention is to provide PPO with an acid group, wherein the acid group is neutralized with a basic metal compound containing a metal element of the group 2B, 3B, 4B or 5B of the periodic table.
Still furthermore, the present invention is to provide a method for miscible preparation of PS and PPO, wherein at least one of PS and PPO has an acid group and the acid group is neutralized with a basic metal compound containing a metal element of the group 2B, 3B, 4B or 5B of the periodic table.
REFERENCES:
patent: 4537925 (1985-08-01), Luxom
patent: 4840982 (1989-06-01), Campbell et al.
patent: 5352727 (1994-10-01), Okada
Inagaki Yasuhito
Noguchi Tsutomu
Tomita Hidemi
Hill & Simpson
Michl Paul R.
Sony Corporation
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