Toyo Boseki Kabushiki Kaisha

Toyo Boeski Kabushiki Kaisha

Kiyoshi Hotta

Fuyuhiko Kubota

Keiichi Uno

Takeshi Ito

Kunio Kimura

Tomohiro Aoyama

Minako Arichi

Yoshihiko Teramoto

Yoshio Araki

Masakatsu Ohguchi

Shoichi Uemura

The present invention provides a purification method of phosphoric acid, which includes bringing phosphoric acid containing arsenic into contact with hydrogen halide, thereby to remove the arsenic from the phosphoric acid, and a purification method of phosphoric acid, which includes bringing phosphoric acid containing arsenic into contact with hydrogen halide in the presence of a compound capable of generating hydrogen halide under acidic conditions. According to the method for purifying phosphoric acid of the present invention, a completely new method for removing arsenic in phosphoric acid is provided, which does not require a filtration or deaeration step or shows a great amount of residual sodium, unlike a sulfide coagulation method. This method is applicable to high concentration phosphoric acid, particularly polyphosphoric acid, and can be practiced at a low cost. In addition, a conventionally nonexistent high purity polyphosphoric acid having an arsenic (As) content of not more than 1 ppm and low contents of heavy metal, silica, sodium and the like can be provided.

Method for purification of phosphoric acid high purity polyphosphoric acid

Aromatic diamine/aromatic dicarboxylate and production method thereof

The present invention provides a method for producing a formed article from a dope comprising a polyphosphoric acid solvent and a polymer soluble in polyphosphoric acid, which includes using a production apparatus containing an apparatus for stirring and uniformly dispersing or homogenizing a dope and a pump apparatus for delivering the uniformly dispersed or homogeneous dope, wherein at least one of the apparatus and the pump apparatus has a part that comes into contact with the dope. According to the present invention, maintenance frequency of production facility due to the corrosion and elution of metal in a recovered solvent can be reduced, which in turn decreases the production cost.

Method for producing formed article from polyphosphoric acid solution

A method for producing polybenzazole, which comprises reacting a PBZ monomer salt with an AA-PBZ monomer or a BB-PBZ monomer in a non-oxidizing solvent having a dehydrating action to give an oligomer, and adding the AA-PBZ monomer or BB-PBZ monomer, which has not been subjected to the above reaction, to allow reaction with the oligomer, whereby to give a polymer having a desired polymerization degree. According to this method, the polymerization degree of the polymer to be obtained finally and of the polymer during production process can be easily controlled.

Method for production of polybenzazole

A polymer having a blocked terminal group according to the present invention, represented by the following Formula (I): ##STR1## where R is an alkylene group containing 1 to 20 carbon atoms; X.sub.1 is an acyl group containing 2 to 50 carbon atoms; Y is H, an alkyl group containing 1 to 50 carbon atoms or an alkenyl group containing 1 to 50 carbon atoms; m is a positive integer; and n.sub.1 is 0 or a positive integer.

Polymer containing lactic acid as its constituting unit and method for

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Shiga, Japan

Kiyoshi Hotta