Title of Invention	" A PROCESS FOR THE PREPARATION OF ACETONE FOR THE SEMICONDUCTORS"
Abstract	This invention relates to a process for the preparation of acetone from commercial grade acetone which comprises in the step of subjecting commercial grade acetone to the step of horizontal fractional distillation, heating for total condensation rate of 2 lit/hr, refluxing for 2 hrs to saturate lower boiler impurities.

Full Text

FIELD OF INVENTION This invention relates to a process for the preparation of acetone for semi conductors. PRIOR ART AND BACKGROUND OF INVENTION An important part of the electronic product reliability achievement is the control of contamination. Contaminants from the environment and/or contaminants introduced during the production and testing operations can create problems with circuits and cause costly failures. Materials used in Electronic industry covers a wide range of materials such a metal, alloys, semiconductors, photoresists, speciality polymers, ceramics, glasses, thick film materials, PCB laminators etc. In the manufacturing process of the component, the cleaning is the most important step to avoid the dust and impurity contamination. The contamination source is from atmosphere, from existing process or from any other foreign matter. The silicone grease is used in electronic assembles and which needs to clean by specific high purity solvents i.e. polar and nonpolar solvents. Oils, fats, resin, waxes are soluble in solvents which are automatically removed by using semiconductor grade solvents. Such foreign contaminants has to be spring-cleaned for better performance of the device. Hydrophilic organic solvents are miscible with water. They are often referred to in the literature as polar solvents. Typical examples of hydrophilic organic solvents used in electronic production cleaning are lower aliphatic alcohols and ketones. The electronic grade acetone is one of the important solvents used for cleaning the components and is presently being imported by electronic industries in India. Removal of critical impurities from commercial acetone is difficult task but can be achieved by using special purification techniques. Acetone is extensively used for a degreasing, cleaning etc. during semiconductor processing in the electronic industries. The purity of the acetone should be very high because traces of impurities would affect the performance of the semiconductor devices. The impurity level of the trace metals should be less than 1ppm. The particulate content should meet specifications of the class 0-2 of the SEMI standard classification i.e. maximum number of particles of 1 micron and above per ml should be less than 10 maximum. Because of stringent purity, specifications and limited requirement, semiconductor grade acetone is not manufactured in India. OBJECTS OF THE INVENTION An object of this invention is to propose a process for the preparation of acetone from commercial grade acetone. BRIEF DESCRIPTION OF INVENTION According to this invention there is provided a process for the preparation of acetone from commercial grade acetone which comprises in the step of subjecting commercial grade acetone to the step of horizontal fractional distillation, heating for total condensation rate of 2 lit/hr, refluxing for 2 hrs to saturate lower boiler impurities. In this process cheap commercial grade acetone is used as a starting material. All the metallic impurities like aluminum, boron, calcium, chromium, copper, gold, iron, lead, manganese, nickel, potassium, sodium, tin, titanium, zinc should be below 10 ppm. The reflux ratio should be varied according to the difficulty of fractionation, rather than be maintaining constant. High efficiency of separation requires a high reflux ratio. Optimum ie. 1:1 reflux was maintained in the distillation process. This is defined as the ratio between the number of moles of vapor returned as refluxed liquid to the fractionating column and the number of moles of final product (collected as distillate), both per unit time. The details of the purification would be more apparent from the following examples: EXAMPLE 1 4 litre of commercial grade acetone was charged in the distillation flask. Some porcelain pieces are added in the flask for unilateral heating. Heating started and adjusted for total condensation rate of 2 lit/hr. Total system equilibrated and the material was refluxed for 2 hrs to saturate lower boiler impurities at the upper side of the distillation column. After 2 hrs reflux the material was collected at the rate of 1 lit/hr. keeping reflux ratio 1:1. 400 ml of the material collected and kept aside as a rejected material. 3.4 lit of the material collected at the rate of 1 lit/hr. in the collector which was totally intact (to avoid the entry of atmospheric moisture in the system). Remaining 200 ml of the material kept at the bottom in the distillation flask as a rejected material. Total time required was approx. 6 hrs. The yield of the process observed was 85%. The final product was chemically analysed using our standard methods as mentioned in testing and evaluation section. The packaging of the final product was done in clean environment i.e. in clean room. EXAMPLE 2 6 lit. of commercial grade acetone was charged in the distillation flask. Some porcelain pieces are added in the flask for unilateral heating. Heating started and adjusted for total condensation rate of 2 lit/hr. Total system equilibrated and the material was refluxed for 2 hrs to saturate lower boiler impurities at the upper side of the distillation column. After 2 hrs reflux the material was collected at the rate of 1 lit/hr. keeping reflux ratio 1:1. 600 ml of the material collected and kept aside as a rejected material. 5.10 lit of the material collected at the rate of 1 lit/hr. in the collector which was totally intact (to avoid the entry of atmospheric moisture in the system). Remaining 300 ml of the material kept at the bottom in the distillation flask as a rejected material. Total time required was approx. 9 hrs. The yield of the process observed was 85%. The final product was chemically analysed using our standard methods as mentioned in testing and evaluation section. The packaging of the final product was done in clean environment i.e. in clean room. EXAMPLES 8 lit. of commercial grade acetone was charged in the distillation flask. Some porcelain pieces are added in the flask for unilateral heating. Heating started and adjusted for total condensation rate of 2 lit/hr. Total system equilibrated and the material was refluxed for 2 hrs to saturate lower boiler impurities at the upper side of the distillation column. After 2 hrs reflux the material was collected at the rate of 1 lit/hr. keeping reflux ratio 1:1. 800 ml of the material collected and kept aside as a rejected material. 6.8 lit of the material collected at the rate of 1 lit/hr. in the collector which is totally intact (to avoid the entry of atmospheric moisture in the system). Remaining 400 ml of the material kept at the bottom in the distillation flask as a rejected material. Total time required was approx. 11 hrs. The yield of the process observed was 85%. The final product was chemically analysed using our standard methods as mentioned in testing and evaluation section. The packaging of the final product was done in clean environment i.e. in clean room. WE CLAIM; 1. A process for the preparation of acetone from commercial grade acetone which comprises in the step of subjecting commercial grade acetone to the step of horizontal fractional distillation, heating for total condensation rate of 2 lit/hr, refluxing for 2 hrs to saturate lower boiler impurities. 2. A process as claimed in claim 1 wherein said commercial grade acetone is refluxed at a reflux ratio of 1:1. 3. A process for the purification commercial grade acetone substantially as herein described and illustrated in the examples.

Documents:

966-del-1999-abstract.pdf

966-del-1999-claims.pdf

966-del-1999-correspondence-others.pdf

966-del-1999-correspondence-po.pdf

966-del-1999-description (complete).pdf

966-del-1999-form-1.pdf

966-del-1999-form-19.pdf

966-del-1999-form-2.pdf

966-del-1999-form-4.pdf

966-del-1999-form-5.pdf

966-del-1999-gpa.pdf

966-del-1999-petition-others.pdf