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
2000-06-01
2002-08-27
Cain, Edward J. (Department: 1714)
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...
C524S493000, C524S495000, C524S496000, C524S847000
Reexamination Certificate
active
06441083
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to a polyamidic acid-containing and fine particles-dispersed composition that has extremely good dispersibility of fine particles even if a polyamidic acid is contained in the composition.
B. Background Art
A polyimide resin is, for example, widely used for various molding materials (e.g. films, sheets), paints (e.g. electric wire enamel), electronic materials, flexible printed substrates, heat-resistant substrates, semiconductor-sealing materials, adhesives, and organic-inorganic-composite materials, because the polyimide resin is excellent, for example, in heat resistance, mechanical properties, chemical resistance and radioactive ray resistance.
Attempts are made to accomplish purposes of, for example, enhancing the physical properties, by adding dielectric fine particles to this polyimide resin. JP-A-172741/1988 discloses diminishing the thermal expansion coefficient by enhancing the heat resistance. JP-A-170548/1991 and JP-A-145378/1994 disclose enhancing the slipping ability and the running durability. JP-A-121364/1989 discloses giving the printability, the heat resistance, and the moisture-resistant adhesion.
In addition, a product by dispersing carbon black into the polyimide resin has light-blocking-off ability and electroconductivity, and is therefore used as a black matrix of a color filter of a liquid crystal display by utilizing the light-blocking-off ability and as an electroconductive paint, a sheet heating element or an electromagnetic wave-absorbing sheet by utilizing the electroconductivity.
A process for producing the polyimide resin, generally, comprises the steps of synthesizing a solvent-soluble polyamidic acid, and then polyimidizing it by heating at 300° C. or higher. Therefore, the step of dispersing dielectric fine particles into a solution of a polyamidic acid is necessary for dispersing the dielectric fine particles into the polyimide resin. As to processes for such dispersing, the following might be thought of: a process comprising the steps of adding dielectric fine particles to a polyamidic acid solution and then dispersing the dielectric fine particles into the polyamidic acid solution with a dispersing machine such as sand mill or ball mill; and a direct dispersing process comprising the steps of adding dielectric fine particles to a half-liquid polyamidic acid varnish and then knead-dispersing the dielectric fine particles with a triple roll. However, mixing the dielectric fine particles with the polyamidic acid causes aggregation of the dielectric fine particles, therefore it is difficult to uniformly disperse the dielectric fine particles, because the affinity between the dielectric fine particle and the polyamidic acid is very bad. For the polyamidic acid solution to be very viscous also makes uniform dispersing difficult. Thus, there is proposed a process comprising the step of synthesizing a polyamidic acid in a dielectric fine particle dispersion, that is, a process comprising the steps of: dispersing dielectric fine particles into an organic polar solvent and then allowing a diamine compound to react with an acid anhydride compound in the resultant dispersion, thus preparing a polyamidic acid solution (JP-A-145378/1994). However, also in this process, the aggregation force between dielectric fine particles is so strong that the aggregation of the dielectric fine particles occurs.
The dielectric fine particles, as aggregated in the above way, have a particle diameter of not smaller than 10 &mgr;m, and are foreign bodies in a sense. Therefore, when molding into the shape of a film, the surface of the resultant film is so rough as to be lusterless, resulting in damaging the appearance of the film, and further, the aggregated dielectric fine particles have bad effects on mechanical properties such as tensile strength and on electric properties such as electric insulation.
Similarly, as to main processes for dispersing carbon black into a solution of a polyamidic acid, the following are well-known: (1) a process comprising the steps of adding carbon black to a polyamidic acid solution and then dispersing the carbon black into the polyamidic acid solution with a dispersing machine such as sand mill or ball mill; (2) a process comprising the steps of adding carbon black to a half-liquid polyamidic acid varnish and then knead-dispersing the carbon black with a triple roll; and (3) a process comprising the step of synthesizing a polyamidic acid in a carbon black dispersion. However, in any of these processes, mixing the carbon black with the polyamidic acid causes aggregation of the carbon black, therefore it is impossible to uniformly disperse the carbon black, because the compatibility between the carbon black and the polyamidic acid is very bad. As a result, the carbon black still remains aggregated in films or coated films of the resultant polyimide. Therefore, there occur problems, for example, of roughness and no gloss of surfaces of the films, and the difficulty of controlling the electric resistance.
SUMMARY OF THE INVENTION
A. OBJECT OF THE INVENTION
An object of the present invention is to provide: a polyamidic acid-containing and fine particles-dispersed composition in which the compatibility between polyimide and fine particle such as dielectric fine particle or carbon black is improved, with the result that the fine particles are uniformly dispersed in a polyamidic acid solution; a production process for such a composition; and a fine particles-dispersed composition which can be effectively utilized as a raw intermediate in this production process.
B. DISCLOSURE OF THE INVENTION
In order to solve the above problems, a polyamidic acid-containing and fine particles-dispersed composition according to the present invention comprises fine particles and a polar solvent solution, wherein the fine particles are dispersed in the polar solvent solution using an organic polymer as a dispersant, and wherein the fine particles are of at least one kind selected from the group consisting of dielectric fine particles, electrosemiconductive fine particles, and electroconductive fine particles, and this composition further comprises a polyamidic acid.
A process for producing the above polyamidic acid-containing and fine particles-dispersed composition according to the present invention comprises: 1) the steps of: dissolving an organic polymer into a polar solvent; adding fine particles to the resultant solution; dispersing the fine particles into this solution to prepare a fine particle dispersion; and mixing the resultant fine particle dispersion and a polyamidic acid solution; wherein the fine particles are of at least one kind selected from the group consisting of dielectric fine particles, electrosemiconductive fine particles, and electroconductive fine particles; or 2) the step of polymerizing a tetracarboxylic dianhydride along with a diamine and/or diisocyanate as raw materials in the fine particle dispersion to prepare a polyamidic acid.
A fine particles-dispersed composition, which can be effectively utilized as a raw intermediate for producing the above polyamidic acid-containing and fine particles-dispersed composition according to the present invention, comprises fine particles and a polar solvent solution, wherein the fine particles are dispersed in the polar solvent solution using an organic polymer as a dispersant, and wherein the fine particles are of at least one kind selected from the group consisting of dielectric fine particles, electrosemiconductive fine particles, and electroconductive fine particles.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.
DETAILED DESCRIPTION OF THE INVENTION
A preferable process for producing the above polyamidic acid-containing and fine particles-dispersed composition according to the present invention comprises the steps of: first preparing the present invention fine particles-dispersed composition, which is explained in detail below, a
Ikeda Hayato
Kuwamoto Tomoyuki
Yamashita Tsuyoshi
Cain Edward J.
Haugen Law Firm PLLP
Nippon Shokubai Co. , Ltd.
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