Title of Invention

AN IMPROVED PROCESS FOR THE PREPARATION OF DETECTOR PAPER FOR THE DETECTION OF TOXIC AGENTS

Abstract

An improved process for the preparation of detector paper which comprises in treating one side of a water repellant paper with a solution of phthalic acid in methanol solvent followed by treatment with paraffin wax in hexane, preparing a dye mixture as herewith described which comprises a plurality of dyes, adding acetone to the dye mixture and stirring, drying the mixture by evaporation for removal of solvent to obtain a solid dried dye mixture, sandwiching the dried mixture between said water repellant paper and a paper sticker as herein described.

Full Text

AN IMPROVED PROCESS FOR PREPARATION OF DETECTOR PAPER This invention relates to a process for preparation of detector paper for the detection of toxic agents like DDVP, parathion, paraoxon and particularly for the detection and identification of chemical warfare agents. Detection papers are convenient way of detecting toxic liquid' agents which do not require any sophisticated instrumentation like chromatography and spectroscopic technique. The residual toxic liquids in any container can be detected on the spot by any untrained/unskilled worker. The appearance of red, yellow or green/green-black colour by the mere touch of the toxic liquid drop..iflfi'icales,.to. tl"ie_ user a presence of toxic substance, harmful to the man as well as animals, thereby saving man from injury or death. These indicator papers do not produce any colour with water, petrol, diesel etc. Detector papers are normally prepared by application of mixture of two dyes and one pH indicator. This mixture is further mixed during paper pulp stages without any special colouring i.e. unbleached. The toxic agent depending on- their nature of solubility, will produce different colours out of three colours mentioned as above. On the basis of spot diameter and density on the detection paper, it is possible to obtain a opinion on the degree of contamination. The disadvantage of the existing process for the preparation of the detector paper seems that these processes require essentially pure dyes which are costly and not readily available commercially. The limitation of existing process is clearly due to dependence on the high purity of dye materials and are not feasible with commercially available dyes which contain dye content to the extent of only 40 to 50%. The primary objective of the present invention is to propose a process for the preparation of the detector paper which is based on the commercially available dyes without jeopardising the detector sensitivity of the detector paper, thereby overcoming the limitation of the existing processes requiring highly pure dyes. Another object of the present Invention Is to provide a process for the preparation of detector paper whfch Is capable of producing the detector paper In limited as well as large quantities as compared to the existing paper pulp based processes, wherein detector paper can be prepared only In bulk quantities Further object of the present Invention is to provide a process for the preparation of detector paper which Incorporates a special dye which imparts the alkell and acid resistance to the detector paper. This special dye therefore makes the detector paper functionary equivalent In terms of sensitivity and dislinctigeness to the detector paper prepared by existing process using high purity dyes. The special dye plugs the microscopic holes and disallows the permeation of alkal and add solutions According to this invention there is provided a process for the preparation of detector paper which comprises in treating one side of a water repellent paper with a solution of phthalic acid followed by treatment with paraffin wax with hexane, preparing a dye mixture consisting of more than two dyes and an indicator blue dye, adding acetone to the dye mixture and stirring, drying the mixture for removal of solvent to obtain, a dried mixture, sandwiching the dried mixture on said water repellant and a paper sticker. In accordance with the is invention a process for preparation of detector paper which employs three different dyes and one different pH Indicator as compared to the existing process which employs two dyes and one pH Indicator. The dyes used In the present process are different from the dyes used In the already existing detector papers. However, the nature and composition of dye used in the present process Is not available freely in the literature. The developed process involves mixing of commercially available solvent soluble dyes of varying concentrations of active Ingredient In definite proportion by weight. The dye mixture is suitably sandwitched between water repellant paper and sticker paper of an appropriate quality. In accordance with this invention both sides of a cellulose absorbent paper such as whatman with a solution of filler paper polystyrene and anthraquinene dye (special dye) in chloroform solvent. By way of example 8% of polystyrene and 0.5 to 1% of anthraquinene dye is added to said solvent. By this treatment, the absorbent paper achieves resistance to alkali and acid solutions and also becomes water repellent. One side of the water repellant paper is treated with 0.5 to 1% of phthalic acid in methanol solvent followed by treatment with paraffin wax in hexane, such as 0.1% paraffin,, This treatment inhibits the appearance of blue tinge on the detection side the paper. A dye mixture of disperse red, disperse yellow and anthraquinone is prepared. The disperse red dye can be like fast red BC, fast red 3BC or fast red 2GB. The disperse yellow dye can be like fast yellow RB, fast yellow GC, fast yellow 2GB, fast yellow 3GB and fast yellow 2GD. An indicator blue dye such as Bromophenol blue from ocresol green, fast navy blue 3GD or fast blue 2R-CN is added to the dye mixture, Acetone is added to the dye mixture as obtained by step and the mixture is stirred. The mixture is then dried by evaporating the solvent acetone by keeping the container on hot water bath. The dried mixture Bowdered to an order of 150 mesh size particles The dye mixture is sandwiched between said water repellent paper and sticker paper of good quality. Example: 5g of disperse red BC and 16g disperse yellow 2GB and 2g blue dye and 2.5g of anthraquinone together and semisolid paste prepared by adding requisite volume of acetone solvent. The mixture is dried by evaporating the solvent on hot water bath. The mixture is powdered to 150 mesh size particles. The mixture sandwitched between water repellent and sticker paper. The paper is then cut into standard sizes (135 mm/75 mm) and dye uncoated surface of the paper is used detection purposes. I CLAIM 1. An improved process for the preparation of detector paper which comprises in treating one side of a water repellant paper with a solution of phthalic acid in methanol solvent followed by treatment with paraffin wax in hexane, preparing a dye mixture as herewith described which comprises a plurality of dyes, adding acetone to the dye mixture and stirring, drying the mixture by evaporation for removal of solvent to obtain a solid dried dye mixture, sandwiching the dried mixture between said water repellant paper and a paper sticker as herein described 2, An improved process for the preparation of detector paper as claimed in claim 1 wherein the water repellant paper is prepared by treatment of both sides of said absorbent filter paper with a solution for example 8% of polystyrene and 0.5% to 1% of anthraquinone dye in a solvent such as chloform,, followed with treatment on one side with 0.5 to 1% of said phthalic acid in methanol solvent and paraffin wax in hexan wherein said paraffin is for example 0.1%. 3 An improved process for the preparation of detector paper as claimed in claim 1 wherein the solid dye mixture is prepared by mixing disperse red dye like fast red BC, fast red 3BC, fast red 2GB which is for example 5 gram with fast yellow dye like fast yellow 2GB, fast yellow 3GB, fast yellow 2GD which is for example 16gm with indicator blue dye like Bromophenol blue, bromocresol green, fast navy blue 3GD, fast blue 2R-CN which is for example 2gm. 4. An improved process for the preparation of detector paper as claimed in calim 1, wherein the evaporation is carried out by keeping the container on hot water bath. 5. An improved process for the preparation of detector paper as claimed in claim 1, wherein powdering of the solid dried mixture is carried out to the order of 150 mesh size particles. 6. An improved process for the preparation of detector paper substantially as herein described and illustrated with reference to example.

Documents:

526-del-1996-abstract.pdf

526-del-1996-claims.pdf

526-DEL-1996-Correspondence-Others-(22-02-2010).pdf

526-del-1996-correspondence-others.pdf

526-del-1996-correspondence-po.pdf

526-del-1996-description (complete).pdf

526-del-1996-form-1.pdf

526-DEL-1996-Form-15-(22-02-2010).pdf

526-del-1996-form-2.pdf

526-del-1996-form-3.pdf

526-del-1996-form-4.pdf

526-del-1996-gpa.pdf