CN87103298A

CN87103298A - Pre-exposure with yellow light to increase the photosensitive speed of photosensitive polymers

Info

Publication number: CN87103298A
Application number: CN 87103298
Authority: CN
Inventors: 格雷戈里·查尔斯·威德
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1986-02-03
Filing date: 1987-05-01
Publication date: 1988-11-16

Abstract

The photopolymerizable composition that contains monomer, light trigger and triarylmethane or xanthene dye, stand intensity at least 1500 lumens/square metre 400 nanometers more than rayed 1 hour or the longer time after, its film speed increases to some extent.The preferred use in 15,000 lumens/square metre exposure down, the time is 10 seconds or longer.Proved that photographic layer protected and that avoid being exposed to oxygen can continue to keep the increase of film speed.

Description

Increasing the photospeed of photopolymer by yellow light pre-exposure

The present invention relates to an improved method for increasing the photospeed of photosensitive polymeric compositions, and more particularly, to a method for achieving higher photospeed by pre-exposure of high intensity yellow light.

In the field of photosensitive polymers, ultraviolet light is used to expose photosensitive polymer compositions, and in order to enable work to be performed under relatively high visibility, studios are often illuminated with yellow light. Working under yellow light for a photosensitive polymeric film is equivalent to working under red light for a silver halide film, except that higher indoor light visibility is a standard requirement for photosensitive polymeric films.

It has long been recognized that photosensitive polymeric compositions can undergo undesirable reactions, which require corrective measures. Thomson, U.S. patent No. 3,144,331, describes a method for modifying or photomodulating a photosensitive polymeric film to maximize possible photopolymerization by pre-exposing the film to at least seventy percent of the actinic radiation intensity required to expose the film. U.S. patent No. 3,598,584 to rasteret et al discloses a method for pre-sensitizing photosensitive polymeric films using relatively low levels of actinic radiation as compared to that used in the imaging step.

Klemchuk in Peter P.Klemchuk review of the effect of pigments on the photostability of polymers (Polymer Photochemistry, 3 rd 1983, pages 1-27) concerns interactions that occur in mixtures of pigment polymers, among the discussed possible mechanisms to explain some complex interactions, including singlet and triplet transitions. In particular, the light absorbing dye can transfer energy to produce singlet oxygen.

Although all of the problems associated with the effect of dyes and defects in photosensitive polymer films are known, there is no recognition that the beneficial effects of the formulation and exposure of photosensitive polymer films can be achieved by using a specific type of coating in the photosensitive polymer composition and actinic radiation at wavelengths typically used to prevent adverse reactions.

The present invention is directed to a treatment process which increases the photospeed of a photopolymerizable composition to subsequent exposure to actinic radiation, the photopolymerizable composition comprising

(a) An addition polymerizable ethylenically unsaturated monomer,

(b) an initiating system activated by actinic radiation, and

(c) a triarylmethane or xanthene dye,

wherein the method comprises

(1) Exposing the photopolymerizable composition to radiation having a wavelength of 400 nm or more and an intensity of at least 1500 lumens per square meter for a time sufficient to increase the photospeed, and

(2) imagewise exposing the photopolymerizable composition increased in photospeed by the step (1) to actinic radiation.

The addition polymerizable ethylenically unsaturated monomers and the actinic radiation activatable initiator system in the process of the present invention are well known in the art for their starting materials. Likewise, the use of dyes in photosensitive compositions is conventional. However, it is critical that the type of dye used to achieve the benefit of increased photospeed be used when using the critical method of pre-exposure disclosed herein.

The desired dye is selected from triarylmethanes or xanthenes. Suitable triarylmethane dyes include: dye index 42595 victoria blue, dye index 42000 basic green 4, dye index 44045 basic blue 26, dye index 42000 victoria green. Suitable xanthene dyes include: dye index 45170 basic violet (rhodamine B), dye index 45380 acid red 87 (eosin Y), dye index 45440 acid red 94 (rose red), dye index 45160 basic red 1. Although not known with certainty, it is believed that these dyes are capable of converting oxygen to its singlet state in the photosensitive polymeric composition.

The advantage of increased photospeed of photosensitive polymeric compositions is seen in the critical combination of an addition polymerizable ethylenically unsaturated monomer, an initiating system activated by actinic radiation and a triarylmethane or xanthene dye, with the treatment being pre-exposed to actinic radiation of a desired wavelength. It is important that the pre-exposure of the composition is performed with light having a wavelength of at least 400 nm. Typically, the upper limit of the wavelength is 800 nm, and preferably not more than 700 nm. The preferred wavelength range is from 400 nm to 800 nm, and preferably from 430 nm to 700 nm.

The wavelength of actinic radiation used herein is that which comprises yellow light, which is typically used in the processing of photosensitive polymeric compositions. However, the intensity of such light, which is typically used as background illumination, is not sufficient to obtain the useful results of the photospeed obtained here. In laboratories designed for processing photosensitive polymeric compositions, the level of illumination that provides a comfortable level of yellow light is typically on the order of 860 lumens per square meter. At this light intensity, the photosensitive polymeric composition is mixed, coated and inspected by methods commonly used to treat silver halide emulsions and films in a red dark room.

After 1 to 2 hours of application of light having an intensity of 1500 lumens per square meter to a photosensitive polymeric composition containing a triarylmethane or xanthene dye or both, an increase in the photospeed was observed over the disclosed wavelength range as compared to the same film sample exposed to 860 lumens per square meter of yellow room light for 24 hours. If the intensity is, for example: at least 3000 or 5000 lumens per square meter, shorter exposure times may be used. In non-actinic yellow light at an intensity of 15,000 lumens per square meter, the photospeed of the film can be greatly increased even with exposure times as short as 10 seconds, while the same film is substantially unaffected by yellow room light. Thus, there is no response to a yellow room exposure, i.e., a threshold of exposure intensity is clearly indicated. In the present invention, higher exposure intensities can be used to compensate for the time-working limitations of the exposure. Is used in

The minimum increase in photospeed, measured as the number of stages of development on the film exposed on the stepped wedge, will be at least 2 to 3 stages, and more commonly at least 3 to 12 stages. However, it is possible to obtain an increase in the photosensitive speed of at least 15 steps.

An advantage of the present invention is that if the high intensity yellow light exposure is included in the design of the processing machinery of the sheet or web of photosensitive polymeric composition, the process can be automated. Also, since the yellow light exposure is non-actinic and non-imagewise, it may be combined with other steps, such as lamination or de-lamination prior to imagewise actinic exposure, such as actinic radiation exposure.

It is a further advantage of the present invention that the photopolymerizable composition does not reach its maximum sensitivity before exposure to non-actinic radiation having a wavelength of at least 400 nm and an intensity of at least 1500 lumens per square meter. The photosensitive polymeric composition is therefore less sensitive to diffuse radiation during manufacture, storage and ready for use than it is to be exposed imagewise.

It has been found that the presence of oxygen (e.g. in air) can reverse the effect of yellow light exposure if the photosensitive polymeric composition is stored. However, the advantage of the present invention is that the effect of oxygen is reversible. For example, if the photopolymerizable composition is not used for a short time after exposure to yellow light, e.g., 1 or 2 hours, but is stored before exposure to actinic radiation, the photospeed will be greatly reduced, resulting in a close to or equal to the original photospeed. However, by performing the yellow exposure again in the above-described manner, the increase in the light-sensitive speed can be obtained again.

Another process for maintaining the increase in photospeed after yellow light exposure is to keep the polymeric composition substantially free of oxygen. One approach is to use a material that is somewhat impermeable to oxygen. While with a barrier that is more oxygen tight, protection may be increased. In the case where the photosensitive polymer composition is coated on a support, the barrier layer may include: for example, polyethylene terephthalate, resin-or gelatin-coated polyethylene terephthalate, cellulose acetate, plastics or metals, which, in the case of plastics as the support, are more oxygen-permeable than polyethylene terephthalate, it is preferred to coat the plastics with an oxygen-impermeable layer. This oxygen impermeable layer may comprise gelatin, gum arabic, polyvinyl alcohol polyacrylonitrile, or similar synthetic polymers. Hydrogenated polyvinyl alcohols are particularly suitable as oxygen-impermeable layers on top of or below layers containing triarylmethane or xanthene dyes. In an automated process, the photosensitive polymeric composition will receive actinic exposure immediately after the yellow exposure, thus eliminating the need for an oxygen impermeable layer.

As previously mentioned, the components of the photosensitive polymeric composition are well known in the art, and it comprises an addition polymerizable component which comprises an addition polymerizable ethylenically unsaturated monomer and an initiator which is activatable by actinic radiation. A thermal polymerization inhibitor is usually also used, as is customary in the prior art.

The photosensitive polymeric composition may be a liquid or may be used in a preferred form as a film, such as a film coated on a support. The photosensitive polymeric film usually contains a polymer binder.

Monomers that can be used alone or in combination with others include: t-butyl acrylate, 1, 5-pentanediol diacrylate, N, N-diethylaminoethyl acrylate, ethylene glycol diacrylate, 1, 4-butanediol diacrylate, diethylene glycol diacrylate, 1, 6-hexanediol diacrylate, 1, 3-propanediol diacrylate, 1, 10-decanediol dimethacrylate, 1, 4-cyclohexanediol diacrylate, 2, 2-hydroxymethylpropane diacrylate, glycerol diacrylate, tripropylene glycol diacrylate, glycerol triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, polyoxyethylated trimethylolpropane triacrylate and trimethacrylate, and similar compounds as disclosed in U.S. Pat. No. 3,380,831, 2, 2-bis- (p-hydroxyphenyl) monopropane diacrylate, pentaerythritol tetraacrylate, 2, 2-bis- (p-hydroxyphenyl) -propane dimethacrylate, triethylene glycol diacrylate, polyoxyethylene-2, 2-bis- (p-hydroxyphenyl) -propane dimethacrylate, bis- (3-methacryloxy-2-hydroxypropyl) bisphenol-A ether, bis- (2-methacryloxyethyl) -bisphenol-A ether, bis- (3-acryloyloxy-2-hydroxypropyl) -bisphenol-A ether, bis- (2-acryloyloxyethyl) -bisphenol-A ether, bis- (3-methacryloxy-2-hydroxypropyl) tetrachlorobisphenol-A ether, bis- (2-methacryloyloxyethyl) tetrachloro-bisphenol A ether, bis- (3-methacryloyloxy-2-hydroxypropyl) tetrabromo-bisphenol A ether, bis- (2-methacryloyloxyethyl) tetrabromo-bisphenol A ether, bis- (3-methacryloyloxy-2-hydroxypropyl) -1, 4-butanediol ether, bis- (3-methacryloyloxy-2-hydroxypropyl) diphenolic acid ether, triethylene glycol dimethacrylate, polyoxypropyltrimethylolpropane triacrylate (462), ethylene glycol dimethacrylate, butanediol dimethacrylate, 1, 3-propanediol dimethacrylate, 1, 2, 4-butanetriol trimethacrylate, 2, 4-trimethyl-1, 3-pentanediol dimethacrylate, pentaerythritol trimethacrylate, 1-phenylethylene-1, 2-methacrylate, pentaerythritol tetramethacrylate, trimethylolpropane trimethacrylate, 1, 5-pentanediol dimethacrylate, diallyl fumarate, styrene, 1, 4-benzenedimethanol dimethacrylate, 1, 4-diisopropenylbenzene, and 1, 3, 5-triisopropenylbenzene.

One class of monomers are diacrylates of alkylene or polyalkylene glycols prepared from alkylene glycols having 2 to 15 carbons or polyalkylene glycol ethers having 1 to 10 ether linkages, and those disclosed in U.S. Pat. No. 2,927,022, for example, those having a large number of addition-polymerizable ethylenic bonds, particularly when the vinyl bond is a terminal bond. Particularly preferred are those compounds in which at least one, and preferably more than one, of such bonds is conjugated to a double-bonded carbon atom, including carbon atoms doubly bonded to carbon and heteroatoms such as nitrogen, oxygen and sulfur. Most preferred are those compounds in which the ethylenically unsaturated groups, especially vinylidene groups, are conjugated to ester or amide structures.

Preferred free-radically initiated addition polymerization initiators which can be activated by actinic radiation and are thermally inert below 185 ℃ include substituted or unsubstituted polycyclic quinones which have two inner ring carbon atoms in the conjugated carbocyclic ring system, e.g., 9, 10-anthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1, 4-naphthoquinone, 9, 10-phenanthrenequinone, 1, 2-benzoanthraquinone, 2, 3-benzoanthraquinone, 2-methyl-1, 4-naphthoquinone, 2, 3-dichloronaphthoquinone, 1, 4-dimethylanthraquinone, 2, 3-dimethylanthraquinone, 2-phenylanthraquinone, 2, 3-diphenylanthraquinone, alpha-sulfonic acid anthraquinone sodium salt, 3-chloro-2-methylanthraquinone, 1-methyl-7-isopropylphenanthrenequinone, 7, 8, 9, 10-tetrahydrotetrabenzoquinone, and 1, 2, 3, 4-tetrahydrobenzanthracene-7, 12-dione. Other useful initiators are given in U.S. patent 2,760,863, although some may be thermally active at temperatures as low as 85 ℃, and include vicinal ketals such as benzoin, hexamethyl butanonol, acyloin ethers such as benzoin methyl or ethyl ethers, alpha-hydrocarbon substituted aromatic benzoins including alpha-methyl benzoin, alpha-allyl benzoin and alpha-phenyl benzoin. Photoreducible dyes and reducing agents disclosed in U.S. Pat. Nos. 2,850,445, 2,875,047, 3.097,096, 3,074,974, 3,097,097, and 3,145,104, and dyes of the phenazine, oxazine, and quinone classes, Michler's ketone, benzophenone, the dimer of 2, 4, 5-triphenyl-imidazolyl and hydrogen donors, and mixtures thereof, as described in U.S. Pat. Nos. 3,427,161, 3,479,185, and 3,549,367, all can be used as initiators. Similarly, cyclohexadienone compounds of U.S. Pat. No. 4,341,860 can be used as initiators. Still other compounds useful as photoinitiators and photoinhibition inhibitors are those sensitizers disclosed in U.S. patent No. 4,162,162.

The thermal polymerization inhibitor which can be used in the photopolymerizable composition is: p-methoxyphenol, hydroquinone, alkyl and alkyl substituted hydroquinones and quinones, t-butyl catechol, hydroquinone, copper resinate, naphthylamine, beta naphthol, cuprous chloride, 2, 6-di-t-butyl-p-cresol, phenothiazine, pyridine, nitrobenzene and dinitrobenzene, p-toluquinone and tetrachlorobenzoquinone further nitroso compounds disclosed in U.S. Pat. No. 4,168,982 as thermal polymerization inhibitors.

If used, the binders which may be used alone or in combination with one another are: polyacrylates and alpha-alkyl polyacrylates, such as polymethyl methacrylate and polyethyl methacrylate, polyvinyl esters, such as polyvinyl acetate, polyvinyl acetate/acrylate, polyvinyl acetate/methacrylate and hydrolyzed polyvinyl acetate, ethylene/vinyl acetate copolymers, polystyrene polymer copolymers, such as copolymers with maleic anhydride and esters, 1, 1-dichloroethylene copolymers, such as 1, 1-dichloroethylene/acrylonitrile, 1, 1-dichloroethylene/methacrylate and 1, 1-dichloroethylene/vinyl acetate copolymers, polyvinyl chlorides and copolymers, such as polyvinyl chloride/vinyl acetate, saturated and unsaturated polyurethanes, synthetic rubbers, such as butadiene/acrylonitrile, acrylonitrile/butadiene/styrene, methacrylate/acrylonitrile/butadiene/styrene copolymers, 2-chloroprene-1, 3-polymers, chlorinated rubbers and styrene/butadiene/styrene, styrene/isoprene/styrene block copolymers, high molecular weight polymersPolyethylene oxides of glycols having an average molecular weight of 4,000 to 1, 000.000, epoxy compounds, e.g. containing acrylic or methacrylic groups, copolyesters, e.g. of formula HO (CH)₂）_nA polyester prepared from the reaction product of a polymethylene glycol of OH (where n is an integer of 2 to 10) with: (1) hexahydroterephthalic acid, sebacic acid and terephthalic acid, (2) terephthalic acid, isophthalic acid and sebacic acid, (3) terephthalic acid and sebacic acid, (4) terephthalic acid and isophthalic acid, and (5) a mixture of copolyesters prepared from the above-mentioned diols and (i) terephthalic acid, isophthalic acid and sebacic acid, and (ii) terephthalic acid, isophthalic acid, sebacic acid and adipic acid, nylons or polyamides, such as N-methoxymethylpoly-1, 6-hexylenediamine, cellulose esters, such as cellulose acetate, cellulose acetate succinate and cellulose acetate butyrate, cellulose ethers, such as methylcellulose, ethylcellulose and benzylcellulose, polycarbonates, polyvinyl acetals, such as polyvinyl butyral, polyvinyl formal, polyoxymethylene.

If developed with an aqueous solution, the binder should contain sufficient acidic or other groups. So that the composition can be treated with an aqueous developer. Useful aqueous solution-processable adhesives include those disclosed in U.S. patent 3,458,311 and U.S. patent 4,273,857. Useful amphoteric polymers include interpolymers derived from N-alkylacrylamides or methacrylamides, acidic film-forming comonomers, and alkyl and hydroxyalkyl acrylates, such as those disclosed in U.S. Pat. No. 4,293,635. In aqueous development, the unexposed portions of the photosensitive layer are removed, but the photosensitive layer will be substantially unaffected by liquids, such as an aqueous solution containing 2% by weight sodium carbonate, during aqueous development.

Many photopolymerizable compositions can be used in the practice of the present invention in both liquid and film forms. These include photoresists, solder masks, interlayers, printing plates, protective films and films for continuous or automated operations. Some of the prior art discloses suitable compositions (including compositions containing the dyes discussed herein), for example, U.S. Pat. Nos. 3,469,982; 3,547,730; 3,526,504 and 4,293,635, as well as numerous other publications. In these methods, the photopolymerizable composition is imagewise exposed to radiation, i.e., selected portions of the composition are exposed.

The following examples are provided to illustrate the invention. All ingredients and percentages are by weight and temperatures are in degrees Celsius, unless otherwise indicated. Example 1 describes the best mode.

Example 1

The photosensitive molecular composition is prepared from the following components:

polymer adhesive MMA/EA/MAA (51/29/20)

Glass transition temperature Tg of 87 ° acid number 127, 62.5

Molecular weight 45,000

Ethyl p-dimethylamino benzoate

(available from Exitol Chemicals) 2.0

Ethylene oxide Polymer molecular weight 400, 0000.5

Ethoxylated trimethylolpropane triacrylate 25.0

4.0 based on hydroxyethyl acrylate toluene diisocyanate

Diacrylated polyurethanes, and polypropylene glycols

Michler's ketone 0.15

Benzophenone 5.2

Colorless crystal violet 4, 4' -methine-tris-N, N-

Dimethylaniline 0.3

Diethylhydroxylamine 0.2

4-trichloromethyl-4-methylcyclohexadienone 0.1

Victoria green dye

Dye index 420000.04

Victoria blue dye

Dye index 425950.02

MMA is methyl methacrylate

EA is ethyl acrylate

MAA is methacrylic acid

The composition was dissolved in 93% dichloromethane/7% methanol and coated onto a polyethylene terephthalate support and dried to produce an experimental photoresist film which was developed in dilute alkali.

A blank film was prepared in which neither victoria green nor victoria blue dye was added.

Laminating blank and experimental films on Maile

The polyethylene terephthalate was coated and exposed to light using 4 40-watt Hillwania Goodh F40/60 fluorescent tubes. The exposure was measured with a general electric 214 type luminometer. All films were exposed at 27,000 lumens per square meter for 120 seconds. Then pass through

The film was exposed to 70 mJ/cm actinic light using a Fraunhofer 41 step wedge, the cover was removed and the image was developed in 1% aqueous sodium carbonate. Examination of the developed step wedge revealed that the yellow light exposure results indicated a 1 to 12 step increase in the dye-containing film, while the blank sample showed no increase in photospeed.

The blank film and the experimental film were also laminated on copper and etched as photoresist. The experimental film pre-exposed with high intensity yellow light has equivalent performance in corrosion and stripping tests similar to those used in printed wiring board manufacture, while having a higher photospeed.

The test was repeated with an exposure time of 3 hours at 1700 lumens/square meter. The experimental films showed a speed increase of 2 to 6 steps, while the blanks showed no speed increase due to non-actinic exposure.

Example 2

The blank and experimental films were compared as in example 1, except that an azo dye, Luxol Fastblue (Luxol Fast Blue), was added to the experimental film. When the films exposed by the conventional method and the film exposed by the yellow pre-exposure method in example 1 were compared, no difference in the photospeed was observed, indicating that such a dye is not included in the scope of the present invention.

Example 3

Photosensitive polymeric compositions were prepared as in example 1 except that each experimental film contained 0.04% of one of the following dyes: victoria blue, victoria green or rhodamine B.

Samples of blank and experimental films were laminated to various surfaces including: non-scrubbed copper, fiberglass, polyvinyl alcohol coated copper, aluminum foil, nickel alloy foil, and polyethylene terephthalate.

The laminated sample was then given the following different yellow light exposures before being subjected to a 65 mj/cm uv exposure: yellow room light for 24 hours, 1500 lumens per square meter for 2 hours and 1, 5000 lumens per square meter for 15 seconds.

If a 24 hour yellow room light exposure is given before the actinic uv exposure by the step wedge, no difference between the blank mold and the experimental film is observed for the post-exposure and developed samples. For any of the yellow pre-exposures, the photospeed of the blank film was unchanged, while the increase in photospeed of the films containing Victoria green, Victoria blue or rhodamine B was similar or greater than that of example 1.

Example 4

The composition of example 1 was coated on a support and no further treatment was carried out, as a blank. A coating of the same composition was overcoated with hydrolyzed polyvinyl alcohol to form a clear top layer. Both films were exposed to high intensity yellow light and immediately developed as in example 1, both of which showed higher photospeeds than they were exposed to only ordinary ultraviolet light prior to development. And (3) performing high-intensity yellow light exposure on the membrane coated with the surface layer and standing for 24 hours before ultraviolet exposure and development. In this case, the blank film without an oxygen-permeable protective layer had no increase in the photospeed, while the film coated with the surface layer had the same increase in the photospeed as that in the test immediately after the pre-exposure.

Example 5

8 films were prepared according to the method in 1 except that the amounts of leuco crystal violet, victoria green and victoria blue were changed according to a statistical scheme. Membrane 5 and membrane 8 example 1 was repeated. The film was laminated on a copper plate. And half of the plate was exposed to yellow light. The exposed and unexposed portions of each plate were then given a 70 mJ/m UV exposure through a one-step wedge. The standing time after the exposure to yellow light and ultraviolet light was 10 minutes. After removal of the cover layer, the copper plate was developed with a 1% sodium carbonate solution at 29 ℃. The number of levels obtained in the yellow light-exposed portion is compared with the number of levels obtained in the non-yellow light-exposed portion. The results are given in table 1.

TABLE 1

Increase of progression

Multidimensional colorless, 16,000 lumens/square meter, 26,000 lumens/square meter

Film crystal violet blue green 11 minutes 2 minutes

1 - - - 1 0

2 - 0.02 - 15 12

3 - - 0.04 8 3

4 - 0.02 0.04 12 10

5 0.3 - - 1 0

6 0.3 0.02 - 14 9

7 0.3 - 0.04 3 1

8 0.3 0.02 0.04 11 4

Since the zero to 1 order increase is within experimental error, these results indicate that victoria blue and victoria green, rather than leuco crystal violet, are contributing significantly to the increase in yellow light.

Example 6

To determine whether this yellow light exposure is still effective in an automated device without a cover layer, a determination was made. The film of example 1 was laminated on a support, and the cover layer was removed. The film was immediately exposed to 26,000 lumens per square meter yellow light for 2 minutes followed by exposure to 70 mj/cm uv light for 39 seconds and developed immediately. The blank sample was left for 2 minutes without yellow light exposure. An increase in photospeed of 2 steps was observed during this experiment. However, in the absence of the blanket, the edge portion of the wedge has a reduced speed compared to the portion in the middle of the cell.

Claims

1. A method of increasing the photospeed of a photopolymerizable composition for subsequent exposure to actinic radiation, the photopolymerizable composition comprising:

(a) an addition polymerizable ethylenically unsaturated monomer,

(b) an initiating system activated by actinic radiation, and

(c) a triarylmethane or xanthene dye,

wherein the method comprises the following steps:

(2) imagewise exposing the photopolymerizable composition having the photospeed increased by the step (1) to actinic radiation.

2. The method of claim 1 wherein the increase in photospeed is at least 3

And (4) stages.

3. The method of claim 2 wherein the increase in photospeed is at least 12

And (4) stages.

4. A method as claimed in claim 3, wherein the increase in photospeed is at least 15

And (4) stages.

5. The method of claim 1, wherein the irradiation is in the wavelength range of 400 nm to 800 nm.

6. The method of claim 5, wherein the wavelength is in the range of 430 nanometers to 700 nanometers.

7. The method of claim 1, wherein the exposure of step (1) is for a period of at least 10 seconds.

8. The method of claim 7, wherein the exposure time is at least 2 minutes.

9. The method of claim 1, wherein the radiation has an intensity of at least 3.000 lumens per square meter.

10. The method of claim 9, wherein the radiance is at least 15.000 lumens per square meter.

11. The method according to claim 1, wherein substantially all of the surface area of the photopolymerizable composition is protected from direct exposure to oxygen during step (1).

12. The method according to claim 1, wherein the dye is contained in an amount of 0.005% to 0.5% by weight of the photosensitive polymeric composition.

13. The method according to claim 12, wherein the dye is contained in an amount of 0.01 to 0.1% by weight of the photosensitive polymeric composition.

14. The method of claim 13, wherein the dyes comprise victoria green, victoria blue, and rhodamine B.

15. A method of increasing the photospeed of a photopolymerizable composition to a subsequent exposure to actinic radiation, the photopolymerizable composition being in the form of a film comprising:

(a) an addition polymerizable ethylenically unsaturated monomer,

(b) an initiation system activated by actinic radiation,

(c) a polymer binder, and

(d) a triarylmethane or xanthene dye,

wherein the method comprises the following steps:

(2) exposing the photopolymerizable composition having the photospeed increased by the step (1) to actinic radiation to achieve exposure of a portion of the composition to actinic radiation and non-exposure of another portion.

16. The method of claim 15, wherein the increase in photospeed is at least 3

And (4) stages.

17. The method of claim 16 wherein the increase in photospeed is at least 12

And (4) stages.

18. The method of claim 17 wherein the increase in photospeed is at least 15

And (4) stages.

19. The method of claim 15, wherein the radiation has a wavelength in the range of 400 nm to 800 nm.

20. The method of claim 19, wherein the wavelength is in the range of 430 nanometers to 700 nanometers.

21. The method of claim 15, wherein the exposure time in step (1) is at least 10 seconds.

22. The method of claim 21, wherein the exposure time is at least 2 minutes.

23. The method of claim 15, wherein the radiation intensity is at least 3.000 lumens per square meter.

24. The method of claim 23, wherein the radiation has an intensity of at least 15.000 lumens per square meter.

25. The method according to claim 15, wherein the dye is contained in an amount of 0.005% to 0.5% by weight of the photosensitive polymeric composition.

26. The method of claim 25, wherein the dye is present in an amount of 0.01% to 0.1% by weight of the photosensitive polymeric composition.

27. The method of claim 26, wherein the dyes comprise victoria green, victoria blue and rhodamine B.