Title of Invention	"AN IMPROVES PROCESS FOR RAPID DEPOSITION OF CONDUCTING POLYMER FILMS ON INSULATING SUBSTRATES"
Abstract	The invention relates to an improved process for rapid deposition of conducting polymer films on insulating substrates. The conducting polymers films are used often for shielding the electronic parts or circuits from electromagnetic interference or radio frequency noise. In such cases the conducting polymer films are required to be deposited on glass, phenolic and epoxy circuit boards, moulded plastic components etc. In order to utilize the vapour phase polymerization of conducting polymers for industrial production it is essential to reduce the deposition time and simultaneously obtain high conductivity value.By addition of metal complexing agent having cation binding property such as phthalocyanine the speed of deposition of conducting polypyrrole and the value of conductivity increases.

Title of Invention

"AN IMPROVES PROCESS FOR RAPID DEPOSITION OF CONDUCTING POLYMER FILMS ON INSULATING SUBSTRATES"

Abstract

The invention relates to an improved process for rapid deposition of conducting polymer films on insulating substrates. The conducting polymers films are used often for shielding the electronic parts or circuits from electromagnetic interference or radio frequency noise. In such cases the conducting polymer films are required to be deposited on glass, phenolic and epoxy circuit boards, moulded plastic components etc. In order to utilize the vapour phase polymerization of conducting polymers for industrial production it is essential to reduce the deposition time and simultaneously obtain high conductivity value.By addition of metal complexing agent having cation binding property such as phthalocyanine the speed of deposition of conducting polypyrrole and the value of conductivity increases.

Full Text	This invention relates to AN IMPROVED PROCESS FOR RAPID DEPOSITION OF CONDUCTING POLYMER FILMS ON INSULATING SUBSTRATES. The conducting polymer films are used often for shielding the electronic parts or circuits from electromagentic interference or radio frequency noise. In such cases the conducting polymer films are required to be deposited on insulating substrates such as glass filled epoxy or phenolic sheets, plastic moulded boxes, chasis etc. In the past the conducting polymer films have been usually grown by electrochemical techniques which requires the substrates to be metallic or conducting. In order to deposit the conducting polymer films on insulating substrates, these have to be pretreated with a coating containing the complexing agent followed by electroless plating which increases its surface conductivity . In another method the insulating surface is treated with an electron acceptor which initiates the polymerization process and then expose the same to monomer vapours. However, the polymerization and depostion of the conducting polymer by such methods takes few hours which is not amenable for continuous production in the industry. Further, the conductivity obtainable by these processes using vapour phase polymerization depends on the time of exposure and the concentration of the dopant used. It is limited to values less than 10~3 (ohm-cm)-1 for practically possible levels of the complexing agent and the exposure time used. The prior art of deposition of conducting polymer films on insulating substrates consists of making a solution of a complex of polymer containing ether group with an electron acceptor, adding to it another film forming polymer, dip-coating the substrate in the solution, drying the same and exposing it to pyrrole vapours for long periods as described in our pending patent (287/DEL/95). However, this process is quite slow and the time of exposure to pyrrole vapours exceeds 1 hr for developing high conductivity. In order to utilise the vapour phase polymerization of conducting polymers for industrial production, it is essential to reduce the deposition time and simultaneously obtain high conductivity value. The present invention relates to these improvements in the deposition of conducting polymer films on insulating substrates. The main objective of the present invention is therefore to provide an improved process for rapid deposition of conducting polymer films on insulating substrates such as glass, phenolic and epoxy circuit boards, moulded plastic components etc. and impart high conductivity in the same. Another object of the present invention is to decrease considerably the deposition time required for the formation of conducting polymer film. Accordingly the present invention provides an improved process for rapid deposition of conducting polymer films on insulating substrates which comprises; a) dissolving a polymer having film forming tendency in a suitable solvent such as herein described, b) adding strong electron acceptor selected from cupric chloride, ferric chloride, ferric nitrate in the range of 80 to 100 wt % of polymer which acts as an initiator for pyrrole polymerization, c) stirring for a period of 1 hour, d) adding a metal complexing agent which is a cyclic compound having cationic binding property, selected from phthalocyanines, polyethers, crown ethers, polyphyrins in the range of 20 to 30 wt % of polymer e) mixing for a period of 1 hour to make a slurry, f)coating the said slurry on the insulating substrate such as herein described to form a film, g)drying at room temperature and exposing the said coated substrate to vapour of monomer which is a heterocyclic compound having five member ring for a period of 5 to 50 seconds to form the conducting polymer film having high conductivity. In one embodiment of the present invention, the polymer used for the film formation is selected from polyethylene oxide, polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, polyvinyl alcohol and the like. In another embodiment of the present invention the metal complexing agent has a cyclic structure with cation binding property and is selected from phthalocyanine, porphyrin, crown ethers and the like. In yet another embodiment of the present invention, the monomer used for the conducting polymer formation is a heterocyclic compound which has high vapour pressure at room temperature and is selected from pyrrole, thiophene, furan and the like. In the preferred range of composition, the conducting polymer film can be deposited by the process described in the present invention within very short time (10 to 15 sec) and has high conductivity in the range of 1 to 15 (ohm-cm) "1 which is stable in air over long period of time. The process of the present invention is described with the examples given herein'below which are illustrative only and should not be construed to limit the spirit and scope of the invention : EXAMPLE - 1 The polyethylene oxide ( Mol.Wt. 3xl05) (0.44 gtns) was dissolved in pure methyl alcohol (50 ml) to which was added cupric chloride (0.426 gms) and stirred well for 1 hr. to obtain clear pale green solution. Metal free phthalocyanine (0.132 gms) was added to the solution and milled for 1 hr to form a thick slurry. This was coated on clean glass slides to form a thin coating which was dried at room temperature. The glass slides with thin coating were placed in a desiccator saturated with pyrrole vapour at room temperature for 10 seconds to 100 seconds to form the polypyr-role film then removed and dried. The -properties of these films are given in Table-1. EXAMPLE"-2 The polyvinyl chloride (Mol.Wt.5xl04 ) (0.22 gms) was dissolved in tetrahydrofuran (50 ml) to which were added cupric chloride (0.213 gms) and the solution stirred well to form clear green solution. Metal free phthalocyanine (0.044 gms) was added to the solution and mixed for 1 hr to form a slurry which was uniformly coated on clean glass slides to form thin films. These were dried and then placed in a desiccator saturated with pyrrole vapours at room temperature for 30 seconds to 200 seconds in order to depos- it conducting polymer ' films. The properties of these films are given in Table - 1. EXAMPLE - 3 The polymer polyvinyl chloride ( Mol.Wt. 5xl04 ) (0.23 gms) was dissolved in tetrahydrofuran to which was added cupric chloride .(0.213 gms) and stirred well to obtain clear solution. Clean glass slides were coated uniformly with the above solution to form thin films. These were dried and placed in a desiccator saturated with pyrrole vapours for 30 seconds to 1200 seconds to form polypyrrole. The properties of these films are given in Table - 1. TABLE - 1 (Table Removed) It can be inferred from the data given in Table-1 that by the addition of metal complexing compound having cation binding property such as phthalocyanine in Example-1 and Example-2, one can increase considerably the speed of the deposition of con- ducting polypyrrole and also enhance the value of maximum conductivity obtainable after prolonged polymerization as compared'to the values obtained in Example III which is without the addition of the promoter. The main advantages of the present invention are : 1. Conducting polymer film can be deposited in very short time within 15 sec. 2. Conducting polymer films can be formed directly on insulat ing substrates such as glass, ceramics, epoxy, phenolic board moulded plastic sheets and other such articles . 3. Large area can be covered with conducting polymer films very easily. 4. Complex shaped substrates can be coated with conducting poly mer film very easily 5. The process of depositing conducting polymer films does not require very elaborate equipment. We claim: 1. An improved process for rapid deposition of conducting polymer films on insulating substrates which comprises; a) dissolving a polymer having film forming tendency in a suitable solvent such as herein described, b) adding strong electron acceptor selected from cupric chloride, ferric chloride, ferric nitrate in the range of 80 to 100 wt % of polymer which acts as an initiator for pyrrole polymerization, c) stirring for a period of 1 hour, d) adding a metal complexing agent which is a cyclic compound having cationic binding property, selected from phthalocyanines, polyethers, crown ethers, polyphyrins in the range of 20 to 30 wt % of polymer e) mixing for a period of 1 hour to make a slurry, f)coating the said slurry on the insulating substrate such as herein described to form a film, g)drying at room temperature and exposing the said coated substrate to vapour of monomer which is a heterocyclic compound having five member ring for a period of 5 to 50 seconds to form the conducting polymer film having high conductivity. 2. An improved process as claimed in claim 1 wherein the polymer used is selected from polyethylene oxide, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral,polyvinyl acetate. 3. An improved process as claimed in claims 1 to 2 wherein the substrates such as glass, phenolic and epoxy circuit boards, moulded plastic components are used. 4. An improved process as claimed in claims 1 to 3 wherein the monomer used is selected from pyrrole, substituted pyrrole, thiophene, substituted thiopene, furan. 5. An improved process as claimed in claims'! to 4 wherein the preferable exposure time to monomer vapour is 15 to 25 seconds. 6. An improved process for rapid deposition of conducting polymer films on insulating substrates as substantially described herein before with reference to the examples.

Full Text

This invention relates to AN IMPROVED PROCESS FOR RAPID DEPOSITION OF CONDUCTING POLYMER FILMS ON INSULATING SUBSTRATES.
The conducting polymer films are used often for shielding the electronic parts or circuits from electromagentic interference or radio frequency noise. In such cases the conducting polymer films are required to be deposited on insulating substrates such as glass filled epoxy or phenolic sheets, plastic moulded boxes, chasis etc. In the past the conducting polymer films have been usually grown by electrochemical techniques which requires the substrates to be metallic or conducting. In order to deposit the conducting polymer films on insulating substrates, these have to be pretreated with a coating containing the complexing agent followed by electroless plating which increases its surface conductivity . In another method the insulating surface is treated with an electron acceptor which initiates the polymerization process and then expose the same to monomer vapours. However, the polymerization and depostion of the conducting polymer by such methods takes few hours which is not amenable for continuous production in the industry. Further, the conductivity obtainable by these processes using vapour phase polymerization depends on the time of exposure and the concentration of the dopant used. It is limited to values less than 10~3 (ohm-cm)-1 for practically possible levels of the complexing agent and the exposure time used.

The prior art of deposition of conducting polymer films on insulating substrates consists of making a solution of a complex of polymer containing ether group with an electron acceptor, adding to it another film forming polymer, dip-coating the substrate in the solution, drying the same and exposing it to pyrrole vapours for long periods as described in our pending patent (287/DEL/95). However, this process is quite slow and the time of exposure to pyrrole vapours exceeds 1 hr for developing high conductivity. In order to utilise the vapour phase polymerization of conducting polymers for industrial production, it is essential to reduce the deposition time and simultaneously obtain high conductivity value. The present invention relates to these improvements in the deposition of conducting polymer films on insulating substrates.
The main objective of the present invention is therefore to provide an improved process for rapid deposition of conducting polymer films on insulating substrates such as glass, phenolic and epoxy circuit boards, moulded plastic components etc. and impart high conductivity in the same.
Another object of the present invention is to decrease considerably the deposition time required for the formation of conducting polymer film.
Accordingly the present invention provides an improved process for rapid deposition of conducting polymer films on insulating substrates which comprises; a) dissolving a polymer having film forming tendency in a suitable solvent such as herein described,
b) adding strong electron acceptor selected from cupric chloride, ferric chloride, ferric nitrate in the range of 80 to 100 wt % of polymer which acts as an initiator for pyrrole polymerization, c) stirring for a period of 1 hour, d) adding a metal complexing agent which is a cyclic compound having cationic binding property, selected from phthalocyanines, polyethers, crown ethers, polyphyrins in the range of 20 to 30 wt % of polymer e) mixing for a period of 1 hour to make a slurry, f)coating the said slurry on the insulating substrate such as herein described to form a film, g)drying at room temperature and exposing the said coated substrate to vapour of monomer which is a heterocyclic compound having five member ring for a period of 5 to 50 seconds to form the conducting polymer film having high conductivity. In one embodiment of the present invention, the polymer used for the film
formation is selected from polyethylene oxide, polyvinyl chloride, polyvinyl
acetate, polyvinyl butyral, polyvinyl alcohol and the like.
In another embodiment of the present invention the metal complexing agent
has a cyclic structure with cation binding property and is selected from
phthalocyanine, porphyrin, crown ethers and the like.
In yet another embodiment of the present invention, the monomer used for
the conducting polymer formation is a heterocyclic compound which has high
vapour pressure at room temperature and is selected from pyrrole, thiophene,
furan and the like.
In the preferred range of composition, the conducting polymer film can be
deposited by the process described in the present invention within very short
time (10 to 15 sec) and has high conductivity in the range of 1 to 15 (ohm-cm) "1
which is stable in air over long period of time.
The process of the present invention is described with the examples given herein'below which are illustrative only and should not be construed to limit the spirit and scope of the invention :
EXAMPLE - 1
The polyethylene oxide ( Mol.Wt. 3xl05) (0.44 gtns) was dissolved in pure methyl alcohol (50 ml) to which was added cupric chloride (0.426 gms) and stirred well for 1 hr. to obtain clear pale green solution. Metal free phthalocyanine (0.132 gms) was added to the solution and milled for 1 hr to form a thick slurry. This was coated on clean glass slides to form a thin coating which was dried at room temperature. The glass slides with thin coating were placed in a desiccator saturated with pyrrole vapour at room temperature for 10 seconds to 100 seconds to form the polypyr-role film then removed and dried. The -properties of these films are given in Table-1.
EXAMPLE"-2
The polyvinyl chloride (Mol.Wt.5xl04 ) (0.22 gms) was dissolved in tetrahydrofuran (50 ml) to which were added cupric chloride (0.213 gms) and the solution stirred well to form clear green solution. Metal free phthalocyanine (0.044 gms) was added to the solution and mixed for 1 hr to form a slurry which was uniformly coated on clean glass slides to form thin films. These were dried and then placed in a desiccator saturated with pyrrole vapours at room temperature for 30 seconds to 200 seconds in order to depos-
it conducting polymer ' films. The properties of these films are given in Table - 1.
EXAMPLE - 3
The polymer polyvinyl chloride ( Mol.Wt. 5xl04 ) (0.23 gms) was dissolved in tetrahydrofuran to which was added cupric chloride .(0.213 gms) and stirred well to obtain clear solution. Clean glass slides were coated uniformly with the above solution to form thin films. These were dried and placed in a desiccator saturated with pyrrole vapours for 30 seconds to 1200 seconds to form polypyrrole. The properties of these films are given in Table - 1.
TABLE - 1
(Table Removed)
It can be inferred from the data given in Table-1 that by the addition of metal complexing compound having cation binding property such as phthalocyanine in Example-1 and Example-2, one can increase considerably the speed of the deposition of con-
ducting polypyrrole and also enhance the value of maximum conductivity obtainable after prolonged polymerization as compared'to the values obtained in Example III which is without the addition of the promoter.
The main advantages of the present invention are :
1. Conducting polymer film can be deposited in very short time
within 15 sec.
2. Conducting polymer films can be formed directly on insulat
ing substrates such as glass, ceramics, epoxy, phenolic board
moulded plastic sheets and other such articles .
3. Large area can be covered with conducting polymer films
very easily.
4. Complex shaped substrates can be coated with conducting poly
mer film very easily
5. The process of depositing conducting polymer films does not
require very elaborate equipment.

We claim:
1. An improved process for rapid deposition of conducting polymer films on
insulating substrates which comprises;
a) dissolving a polymer having film forming tendency in a suitable solvent such as herein described, b) adding strong electron acceptor selected from cupric chloride, ferric chloride, ferric nitrate in the range of 80 to 100 wt % of polymer which acts as an initiator for pyrrole polymerization, c) stirring for a period of 1 hour, d) adding a metal complexing agent which is a cyclic compound having cationic binding property, selected from phthalocyanines, polyethers, crown ethers, polyphyrins in the range of 20 to 30 wt % of polymer e) mixing for a period of 1 hour to make a slurry, f)coating the said slurry on the insulating substrate such as herein described to form a film, g)drying at room temperature and exposing the said coated substrate to vapour of monomer which is a heterocyclic compound having five member ring for a period of 5 to 50 seconds to form the conducting polymer film having high conductivity.
2. An improved process as claimed in claim 1 wherein the polymer used is selected
from polyethylene oxide, polyvinyl chloride, polyvinyl alcohol, polyvinyl
butyral,polyvinyl acetate.
3. An improved process as claimed in claims 1 to 2 wherein the substrates such as
glass, phenolic and epoxy circuit boards, moulded plastic components are used.
4. An improved process as claimed in claims 1 to 3 wherein the monomer used is
selected from pyrrole, substituted pyrrole, thiophene, substituted thiopene, furan.
5. An improved process as claimed in claims'! to 4 wherein the preferable
exposure time to monomer vapour is 15 to 25 seconds.

6. An improved process for rapid deposition of conducting polymer films on insulating substrates as substantially described herein before with reference to the examples.

Documents:

264-del-1997-abatract.pdf

264-del-1997-claims.pdf

264-del-1997-complete specification (granted).pdf

264-del-1997-correspondence-others.pdf

264-del-1997-correspondence-po.pdf

264-del-1997-description (complete).pdf

264-del-1997-form-1.pdf

264-del-1997-form-19.pdf

264-del-1997-form-2.pdf

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Patent Number

197239

Indian Patent Application Number

264/DEL/1997

PG Journal Number

N/A

Publication Date

09-Aug-2006

Grant Date

04-Aug-2006

Date of Filing

31-Jan-1997

Name of Patentee

COUNCIL OF SCEINTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110 001, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	RADHAKRISHNAN SUBRAMANIAM	NATIONAL CHEMICAL LABORATORY, PUNE 411 008, INDIA
2	SWATI GANJAN UNDE	NATIONAL CHEMICAL LABORATORY, PUNE 411 008, INDIA

PCT International Classification Number

C08L 67/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA