Claims
1. A light sensitive cross linker comprising of a diazo
compound which is selected from (Compound I) and (Compound II)
wherein, R1 is independently selected from 1-3 alkyl group, alkoxy group, allyloxy group and any hydrocarbon group optionally substituted with oxygen, nitrogen or sulphur, R2 is same or different to that of the groups mention in R1, R3 is independently selected from 1-3alkyl group, allyl group, alkenyl group, alkynyl group and any hydrocarbon group,
X is independently selected from hydrogen, halogen, nitro, cyanide, ketone, 1-3 alkyl group which may be optionally substituted with halogen atom and alkyl ethers which may be optionally substituted with halogen,
wherein, the compound I, compound II and there analogous are used to reduce screen printing curing time using photo-induced isomerisation process.
2. The light sensitive cross linker as claimed in claim 1, wherein the said R1 and R2 are an allyloxy group.
3. The light sensitive cross linker as claimed in claim 1, wherein the said R3 is an allyl group.
4. The light sensitive cross linker as claimed in claim 1,

5. The light sensitive cross linker as claimed in claim 1, wherein the said Compound II is selected from

6. The light sensitive cross linker as claimed in claim 1,
wherein the said cross linker is produced by the process of
thermal back relaxation or a visible light of wavelength in
the range of 400 to 500nm is used.
7. The light sensitive cross linker as claimed in claim 1,
wherein the said light sensitive cross linker additionally
contains a polymeric group.

wherein, R1 is independently selected from 1-3 alkyl group, alkoxy group, allyloxy group and any hydrocarbon group optionally substituted with oxygen, nitrogen or sulphur,
R2 is same or different to that of the groups mention in R1,
R3 is independently selected from 1-3alkyl group, allyl group, alkenyl group, alkynyl group and any hydrocarbon group,
X is independently selected from hydrogen, halogen, nitro, cyanide, ketone, 1-3 alkyl group which may be optionally substituted with halogen atom and alkyl ethers which may be optionally substituted with halogen,

wherein, the compound I, compound II and there analogous are used to reduce screen printing curing time using photo-induced isomerisation process.
2. The light sensitive cross linker as claimed in claim 1, wherein the said R1 and R2 are an allyloxy group.
3. The light sensitive cross linker as claimed in claim 1, wherein the said R3 is an allyl group.
4. The light sensitive cross linker as claimed in claim 1, wherein the said Compound I is selected from

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-fluorophenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-chlorophenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-bromophenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-iodophenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-phenyldiazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-nitrophenyl)diazene

(E)-4-((2,4-bis(allyloxy)phenyl)diazenyl)benzonitrile

(E)-1-(4-((2,4-bis(allyloxy)phenyl)diazenyl)phenyl)ethanone

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(p-tolyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-methoxyphenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-(trifluoromethyl)phenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-(trifluoromethoxy)phenyl)diazene

5. The light sensitive cross linker as claimed in claim 1, wherein the said Compound II is selected from

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-nitrophenyl)diazene

(E)-4-((3-allyl-4-(allyloxy)phenyl)diazenyl)benzonitrile

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(p-tolyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-methoxyphenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-(trifluoromethyl)phenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-(trifluoromethoxy)phenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-phenyldiazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-fluorophenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-chlorophenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-bromophenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-iodophenyl)diazene

6. The light sensitive cross linker as claimed in claim 1, wherein the said cross linker is produced by the process of thermal back relaxation or a visible light of wavelength in the range of 400 to 500nm is used.

7. The light sensitive cross linker as claimed in claim 1, wherein the said light sensitive cross linker additionally contains a polymeric group.

8. The light sensitive cross linker as claimed in claim 1, wherein the said Compound I is (E)-ethyl 4-((2,4-bis(allyloxy)phenyl)diazenyl)benzoate.

9. The light sensitive cross linker as claimed in claim 1, wherein the said Compound II is (E)-ethyl 4-((3-allyl-4-(allyloxy) phenyl) diazenyl) benzoate.

10. A method of photo-induced isomerisation to form the light sensitive cross linker, the method comprising:

a diazo compound with polymerizable groups during the photo- induced isomerization;
a light sensitive material (guest) bind to paint/ink molecule (host); and forms a cross link network and reduces the curing time rapidly during the screen printing process,
wherein, the light sensitive material is selected from Compound I and Compound II,
wherein, the photo-induced isomerisation method is using guest-host cross-link formation to reduce the cost and curing time. , Description:FIELD OF THE INVENTION

The present invention is a novel light-sensitive cross-linker containing diazo compounds that reduces the curing time by using photo- induced isomerisation process.
BACKGROUND OF THE INVENTION

Screen printing is a commonly used technique in the printing technology which involves usage of various combinations of substrates, inks, solvents, pigments, resins and additives to obtain customized printing requirements. In screen printing process, a mesh is used to transfer ink onto a substrate, except in areas made resistant to the ink by a blocking stencil.During the squeeze stroke, the ink is forced into the mesh openings and creates a predefined image by wetting the substrate. As the screen rebounds away from the substrate, the ink remains on the substrate and creates the predefined image. Later, the printed image on the substrate goes through the curing process and hence completes the screen printing process. Curing the screen printed products is one of the key processes required in screen printing technology. The curing time is one of the most important attribute for obtaining the productivity. Industries are using different techniques to accomplish the curing time either curing solvent based inks or the UV inks. Industries are using different techniques to accomplish the curing time either curing solvent based inks or the UV inks. Presently, entire printing industries are struggling to reduce the curing time of printed products and this is one of the reasons for the products to become more expensive. In few instances, the whole curing process takes more than 12 hours for a particular batch which not only consumes lot of electricity due to thermal evaporation or UV light shining but also creates hazardous atmospheres to the working people. Air pollutants like the nasty smells coming out of the paints will remain active for 12 hours until entire curing process are finished. These kind of curing procedures not only reduce the productivity but also increases the time and cost simultaneously. Some typical examples of screen printing process that are using different techniques are listed below
JP4255188B2 discloses a photosensitive resin composition of the present invention, the functional group since using a crosslinkable compound having a light crosslinked saponification degree 50 mol% or more of vinyl acetate polymer saponification of the dispersion medium components as dispersed together is insoluble even more water by combined with hydrophilic groups such as OH groups remaining in the object to reduce the hydrophilic group, the light crosslinked saponification degree 50 mol% or more of vinyl acetate polymer saponified product and are integrated by crosslinking, it is possible to further insolubilized photosensitive resin layer to form an image of the screen printing plate obtained can exhibit very high water resistance, organic solvent resistance, printing durability.
EP2185976 discloses A photosensitive composition includes polyvinyl alcohol (PVA), one or more synthetic resins, at least one cross-linking agent for the PVA and a sensitizer component comprising at least one gelling agent and at least one photosensitive organic compound chosen from diazonium salts. The composition is suitable for the production of rotary printing cylinders, in particular in the textile field.
In the prior art, the existing invention suffers a lot of disadvantages and the existing invention was time consuming, manual processes across services & functions limiting the ability to expand. The existing invention does not enhance the quality. The curing procedures in the existing invention not only reduce the productivity but also increase the time and cost simultaneously. The need therefore has arisen to develop a screen printing process that is capable of overcoming all drawbacks of the existing inventions hence there is need of the present invention.
OBJECTIVE OF THE INVENTION
The main objective of the present invention is to reduce the curing time in screen printing process.
Another objective of the present invention is to increase the productivity during screen printing.
Yet another objective of the present invention is to reduce the cost and time during the screen printing process.
Yet another objective of the present invention is to enhance the quality of the printed product.
Yet another objective of the present invention is to use azobenzene molecules that have high optical stora
Yet another objective of the present invention is to provide a safe and toxic free environment for the people working in screen printing process.
Yet another objective of the present invention is that it reduces the use of electricity, thermal evaporation and UV shining.
Yet another objective of the present invention is that isomerization effect of light on guest-host system for rapid curing process takes only 20 seconds.
Further objectives and features of the present invention will become apparent from the detailed description provided herein below, in which various embodiments of the disclosed invention are illustrated by way of example and appropriate reference to accompanying drawings.

SUMMARY OF THE INVENTION

The present invention relates to a light sensitive crosslinkers containing diazo molecules and these diazo molecules are used extensively in the area of optical storage devices where energetically stable trans conformers converts to metastable cis conformers by shining UV light of wavelength approximately 365 nm within very short time of few seconds (10-20 seconds). Since cis configuration is in metastable state, it will come back to trans configuration after a sometime and this conversion of cis into trans configuration is called the process of thermal back relaxation. Longer the relaxation time better is the optical storage device performance. If addition of polymeric group in to azodyes then it might photo crosslink each other while UV shining and freeze the system as it is and then reverse back to trans might not be possible. Using the same analogy in the present invention the diazo-compound with polymerizable groups are introduced so that during the photo-induced isomerization the light sensitive material (guest) bind to paint/ink molecule (host) and forms a cross link network, reduces the curing time rapidly. The present invention has eliminated the defects of the conventional methods, and the provision of a novel light-sensitive cross-linker that reduces the curing time by using photo- induced isomerisation process as described below in the description agent and a method for using the same.

One of the advantages of the present invention is that the present invention reduces the curing time in screen printing process.

Another advantage of the present invention is that it increases the productivity during screen printing.

Yet another advantage of the present invention is that it reduces the cost and time during the screen printing process.

Yet another advantage of the present invention is that it enhances the quality of the printed product.

Yet another advantage of the present invention is that diazo molecules have high optical storage.

Yet another advantage of the present invention is that it provides a safe and toxic free environment for the people working in screen printing process.

Yet another advantage of the present invention is that it reduces the use of electricity, thermal evaporation and UV shining.

Yet another advantage of the present invention is that isomerization effect of light on guest-host system for rapid curing process takes only 20 seconds.

Further advantages and features of the present invention will become apparent from the detailed description provided herein below, in which various embodiments of the disclosed invention are illustrated by way of example and appropriate reference to accompanying drawings.

DETAILED DESCRIPTION OF THE FIGURES
Figure 1: Isomerization phenomenon of photoinduced effect.
Figure 2: The schematic representation of photo-induced isomerization process between light sensitive material (guest) and paint/ ink (host) in the formation of cross link polymer with reduced curing time.
Figure 3: The Isomerization effect of light on guest-host system for rapid curing process. It takes only 20 seconds with low intensity of 2mW/cm2 to cross link the system. Same has been adopted with paint molecules to permanently cross link the system and fast cure the system.
Figure 4: The entire process works on following diagrams that are shown in the cited figure.
Figure 5: Curing time and the images of different host material (green / red) with guest light sensitive molecule.
Figure 6: The Stability of the light sensitive (guest) and paint (host)using 3: 97 ratio respectively with excellent contrast.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible to embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure of such embodiments is to be considered as an example of the principles and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings. This detailed description defines the meaning of the terms used herein and specifically describes embodiments in order for those skilled in the art to practice the invention.
Definition
The terms “a” or “an”, as used herein, are defined as one or as more than one. The term “plurality”, as used herein, is defined as two or as more than two. The term “another”, as used herein, is defined as at least a second or more. The terms “including” and/or “having”, as used herein, are defined as comprising (i.e., open language). The term “coupled”, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.

The term “comprising” is not intended to limit inventions to only claiming the present invention with such comprising language. Any invention using the term comprising could be separated into one or more claims using “consisting” or “consisting of” claim language and is so intended. The term “comprising” is used interchangeably used by the terms “having” or “containing”.

Reference throughout this document to “one embodiment”, “certain embodiments”, “an embodiment”, “another embodiment”, and “yet another embodiment” or similar terms means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics are combined in any suitable manner in one or more embodiments without limitation.
The term “or” as used herein is to be interpreted as an inclusive or meaning any one or any combination. Therefore, “A, B or C” means any of the following: “A; B; C; A and B; A and C; B and C; A, B and C”. An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.
Screen printing is a commonly used technique in the printing technology which involves usage of various combinations of substrates, inks, solvents, pigments, resins and additives to obtain customized printing requirements. In screen printing process, a mesh is used to transfer ink onto a substrate, except in areas made resistant to the ink by a blocking stencil. During the squeeze stroke, the ink is forced into the mesh openings and creates a predefined image by wetting the substrate. As the screen rebounds away from the substrate, the ink remains on the substrate and creates the predefined image. Later, the printed image on the substrate goes through the curing process and hence completes the screen printing process. Screen printing Inks are one of the key components of screen printing process. Today’s printing inks are composed of a pigment (one of which is carbon black similar to stain used in 2500BC), a binder (an oil, resin or varnish), a solvent and various additives such as drying and chelating agents. Having the right screen-printing supplies is important for all screen-printing business. One of the best supply items you can have is low cure plastisol inks. Non-cotton fabrics, such as polyester and other synthetic performance and moisture-wicking materials are growing in popularity. While they are popular with customers, screen printers quickly realized that these materials are prone to dye-migration, also known as bleeding (the shirt color coming through the screen print ink). The exact recipe for given ink depends on the type of surface that it will be printed on and the printing method that will be used. Inks have been designed to print on a wide range of surfaces from metals, plastics and fabrics to papers. The various printing methods are all similar, ink is applied to a plate/cylinder made of metal or rubber or plastics, which is further applied to the surface to be printed. The image can be raised above the surface of the plate, in the plane of the plate but chemically treated to attract the ink or etched into the plate and the excess ink scraped off. Different inks are produced to suit these different conditions.

The present invention relates to a light sensitive cross linker comprising of a diazo compound which is selected from (Compound I) and (Compound II)

Wherein R1 is independently selected from 1-3 alkyl group, alkoxy group, allyloxy group and any hydrocarbon group optionally substituted with oxygen, nitrogen or sulphur,
R2 is same or different to that of the groups mention in R1,
R3 is independently selected from 1-3alkyl group, allyl group, alkenyl group, alkynyl group and any hydrocarbon group
X is independently selected from hydrogen, halogen, nitro, cyanide, ketone, 1-3 alkyl group which may be optionally substituted with halogen atom and alkyl ethers which may be optionally substituted with halogen. Herein the compound I, compound II and there analogous are used to reduce screen printing curing time using photo-induced isomerisation process.
In another embodiment the said R1 and R2 in the light sensitive cross linker are an allyloxy group. In the preferred embodiment the said R3 in the light sensitive cross linker is an allyl group. In another embodiment the said Compound I is selected from the following groups

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-fluorophenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-chlorophenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-bromophenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-iodophenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-phenyldiazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-nitrophenyl)diazene

(E)-4-((2,4-bis(allyloxy)phenyl)diazenyl)benzonitrile

(E)-1-(4-((2,4-bis(allyloxy)phenyl)diazenyl)phenyl)ethanone

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(p-tolyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-methoxyphenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-(trifluoromethyl)phenyl)diazene

(E)-1-(2,4-bis(allyloxy)phenyl)-2-(4-(trifluoromethoxy)phenyl)diazene

In another embodiment the said Compound II is selected from the following groups

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-nitrophenyl)diazene

(E)-4-((3-allyl-4-(allyloxy)phenyl)diazenyl)benzonitrile

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(p-tolyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-methoxyphenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-(trifluoromethyl)phenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-(trifluoromethoxy)phenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-phenyldiazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-fluorophenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-chlorophenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-bromophenyl)diazene

(E)-1-(3-allyl-4-(allyloxy)phenyl)-2-(4-iodophenyl)diazene

In the preferred embodiment the said cross linker is produced by the process of thermal back relaxation or a visible light of wavelength in the range of 400 to 500nm is used. In another embodiment the said cross linker is produced by the process of thermal back relaxation or a visible light of wavelength in the range of 400 to 500nm is used. In the preferred embodiment the said Compound I is (E)- ethyl 4-((2,4-bis(allyloxy)phenyl)diazenyl) benzoate. In the preferred embodiment the said Compound II is (E)-ethyl 4-((3-allyl-4-(allyloxy) phenyl) diazenyl) benzoate.
In an embodiment the present invention relates to a method of photo-induced isomerisation to form the light sensitive cross linker, the method comprising:
a diazo compound with polymerizable groups during the photo-induced isomerization,
a light sensitive material (guest) bind to paint/ink molecule (host) and forms a cross link network and reduces the curing time rapidly during the screen printing process. Herein the light sensitive material is selected from Compound I and Compound II.

Synthesis and Characterization of the diazo compounds

The diazo compounds and their analogous compounds are synthesized by the below mentioned process.
Synthetic procedure of (E)-ethyl 4-((2,4-dihydroxyphenyl) diazenyl) benzoate (CompoundI)

Compound I

To a stirred solution of Ethyl 4-aminobenzoate (1 equiv.) and hydrochloric acid (15%) was cool to 0 oC, followed by addition of NaNO2 (1 equiv.) dissolved in water added drop-wise at 0-5 °C and the reaction mixture stirred for 15 min at 0-2 °C to produce diazonium salt. Finally, the resorcinol dissolved in methanol (1 equiv.) added slowly at 0-2 °C, further bascified using 10% NaOH to pH 8.5–9 and the reaction mixture agitated for 4h. Diluted the above reaction mixture with cold methanol and acidified to pH 4. The reddish-brown precipitate filtered, dried and recrystallized from methanol. Reddish-brown coloured solid; Rf = 0.42 (30% hexane: ethyl acetate); yield: 70 % to realize the desire compound (E)-ethyl 4-((2,4- dihydroxyphenyl)diazinyl) benzoate. Further, this compound use in the synthesis of (E)-ethyl 4-((2,4-bis(allyloxy)phenyl)diazenyl)benzoate is described.
To a stirred solution of (E)-ethyl 4-((2,4-dihydroxyphenyl)diazinyl) benzoate (1 equiv.), potassium carbonate (4 equiv.) and catalytic amount of potassium iodide in dry butanone. The allyl bromide (4 equiv.) added in portion wise to reaction mixture and reflux for 12 h under nitrogen atmosphere. The completion of reaction is confirmed by TLC. After completion, the solvent was removed under reduced pressure using rota evaporator. The crude product was purified by using column chromatography by eluting 10 % ethyl acetate and hexane and the combined organic fraction was evaporated to get desired product. Yield: 55 %.
(E)-Ethyl 4-((2,4-bis(allyloxy)phenyl)diazenyl)benzoate (Compound I): Rf=0.4, Yield: 55 %; H1-NMR: 400 MHz, CDCl3: d 8.16 (dd, J = 5.6 Hz, 1.6 Hz, 2H, Ar), 7.90 (dd, J = 5.4 Hz, 1.6 Hz, 2H, Ar), 7.78 (d, J = 7.2 Hz, 1H, Ar), 6.63 (d, J = 2.0 Hz, 1H, Ar), 6.58 (dd, J = 2.0 Hz, 7.2 Hz, 1H, Ar), 6.19 - 6.18 (m, 2H), 5.36 (dd, J1 = 12.0 Hz, J2 = 4.0 Hz, 2H, olefinic), 5.34 (d, J1 = 4.0 Hz, J2 = 4.0 Hz , 2H, olefinic), 4.78 (dd, J = 1.2 Hz, 2H,-CH2 × 1), 4.63 (d, J = 1.2 Hz, 2H, -CH2 × 1), 4.41 (q, J = 5.6 Hz, 2H, -CH2CH3), 1.42 (t, J = 5.6 Hz, 3H, -CH2CH3).

Curing the screen printed products is one of the key processes required in screen printing technology. The curing time is one of the most important attribute for obtaining the productivity. Industries are using different techniques to accomplish the curing time either curing solvent based inks or the UV inks. UV curing is quit famous and popular in recent times. UV curing is the process by which ultraviolet light is used to initiate a photochemical reaction that generates a crosslinked network of polymers. UV curing is adaptable to printing, coating, decorating, stereo lithography, and in the assembly of a variety of products and materials. In comparison to other technologies, curing with UV energy may be considered a low temperature process, a high speed process, and is a solvent less process, as cure occurs via direct polymerization rather than by evaporation. Since more than decade the energy curing products have gained significant growth both in coatings and printing techniques. The major energy curing processes used are UV and EB (Ultra violet lamps and Electron Beam). Energy curing technology is important in the production of all types of printing applications, where fast drying, durability and high glossy finish make them sustainable for immediate use, e.g. carton printing, food and pharmaceutical packaging, labels plastic substitutes and metal decoration. Presently, the entire printing industries are struggling to reduce the curing time of printed products and this is one of the reasons for the products to become more expensive. The whole curing process takes more than 12 hours for a particular batch which consumes lot of electricity and due to thermal evaporation and UV light shining in the techniques adopted in screen printing process creates hazardous atmospheres to the working people. Air pollutants like the nasty smells coming out of the paints will remain active for 12 hours until entire curing process is finished. These kind of curing procedures not only reduce the productivity but also increases the time and cost simultaneously. In order to obtain the cost effectiveness and reduce curing time with the same or enhanced quality of the printed products, it is essential to develop a cost effective curing process using light sensitive cross linkers which reduces the curing time phenomenally and would be more compatible with less expensive solvents. The present invention relates to a light sensitive cross linkers containing diazo molecules and these diazo molecules are used extensively in the area of optical storage devices where energetically stable trans conformers converts to metastable cis conformers by shining UV light of wavelength approximately 365 nm within very short time of few seconds (10-20 seconds). Since cis configuration is in metastable state, it will come back to trans configuration after a sometime and this conversion of cis into trans configuration is called the process of thermal back relaxation or else one need to shine visible light of wavelength approximately 450 nm as shown in Figure1.
Longer the relaxation time better is the optical storage device performance. If addition of polymeric group in to azodyes then it might photo crosslink each other while UV shining and freeze the system as it is and then reverse back to trans might not be possible. Using the same analogy in the present invention the diazo- compound with polymerizable groups are introduced so that during the photo- induced Isomerization the light sensitive material (guest) bind to paint/ink molecule (host) and forms a cross link network, reduces the curing time rapidly as shown in the schematic figure 2.
Existing screen printing process in the industries requires more time (~6-12 hours) for the curing process. Traditional method needs approximately 5 to 6 h for curing. As one of the bottle neck for productivity and toxicity of the paints spread over for longer duration,. In the present invention, the proved isomerization method using guest-host cross-link formation is an ideal method to reduce the cost and reduce the curing time less than 60 seconds time in comparison with 12 hours with unchanged process and quality.

Figure 3 describes the Isomerization effect of light on guest-host system for rapid curing process. It takes only 20 seconds with low intensity of 2mW/cm2 to cross link the system. Same has been adopted with paint molecules to permanently cross link the system and fast cure the system. The entire process works on following diagrams is described in Figure 4, Process no 1 to 5 is dedicated for creating permanent labels using crosslinkers and if no 5 fails again need to repeat from no 1. This kind of crosslinking with the paints not only save the money but also makes the process extremely faster. Followings are the curing time studies using light sensitive materials and the host paint, where the wavelength at ? = 365 nm and the intensity 50mW/cm2 and 100mW/cm2.

Table 1. Study of intensity on the thickness of the samples comprising of both light sensitive and paintmaterials.

MATERIAL CODE TIME
(I=50mW/cm2) TIME
(I=100mW/cm2)
500G

500 Mat 70sec

60sec 40sec

40sec
250G

250Mat 40 sec

60 sec 40sec

20sec
180G

180Mi 60 sec 30sec

80sec
125G

125Mat 40sec

60sec 20sec

20sec

Further objectives, advantages and features of the present invention will become apparent from the detailed description provided herein below, in which various embodiments of the disclosed present invention are illustrated by way of example and appropriate reference to accompanying drawings. Those skilled in the art to which the present invention pertains may make modifications resulting in other embodiments employing principles of the present invention without departing from its spirit or characteristics, particularly upon considering the foregoing teachings. Accordingly, the described embodiments are to be considered in all respects only as illustrative, and not restrictive, and the scope of the present invention is, therefore, indicated by the appended claims rather than by the foregoing description or drawings. Consequently, while the present invention has been described with reference to particular embodiments, modifications of structure, sequence, materials and the like apparent to those skilled in the art still fall within the scope of the invention as claimed by the applicant.