CA2018954C - Method of developing photopolymerizable printing plates and composition therefor - Google Patents
Method of developing photopolymerizable printing plates and composition thereforInfo
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- CA2018954C CA2018954C CA 2018954 CA2018954A CA2018954C CA 2018954 C CA2018954 C CA 2018954C CA 2018954 CA2018954 CA 2018954 CA 2018954 A CA2018954 A CA 2018954A CA 2018954 C CA2018954 C CA 2018954C
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- methylpyrrolidone
- nonionic surfactant
- nonylphenolpolyethylene
- limonene
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Abstract
A method and composition for developing an image formed by exposing a portion of a photopolymerizable layer to actinic radiation and removing the portion of the photo-polymerizable layer not exposed to actinic radiation by washing the unexposed portion to the developer composition comprising a monoterpene, N-methylpyrrolidone and an aro-matic alcohol. Optionally, a nonionic surfactant can be included in the developer composition.
Description
20 ~ 8954 METHOD OF DEVELOPING PHOTOPOLYMERIZABLE PRINTING PLATES
AND COMPOSITION THEREFOR
BACKGROUND OF THE INVENTION
The present invention relates to an improved method and composition for developing a relief image by imagewise exposing a photopolymerizable layer to actinic radiation and subsequently removing the uncured material of the photopolymerizable layer by use of a developer composition to produce the relief image.
In the following description and claims, the term "cured" and derivatives thereof shall be used to describe material obtained by (1) the photopolymerization of mono-meric or low molecular weight compounds, or (2) the cross-linking of photocrosslinkable polymers. The term "uncured"
and derivatives thereof shall be used to describe material which has not undergone photopolymerization or photocross-linking.
The use of actinic radiation, such as ultraviolet light, to form a relief pattern or image by the imagewise curing of a photopolymerizable layer is well known in the art and is typically used in preparing flexographic print-ing plates and relief patterns on semiconductor layers.
These relief images or patterns are formed by placing an image-bearing process transparency, for example, a line or half-tone negative, over the photopolymerizable layer. The negative is designed to transmit actinic radiation through certain portions of it and to absorb or reflect actinic radiation at other portions so that the photopolymerizable layer underneath the negative is cured imagewise according to the portion of the negative that transmits the radia-tion. A transparent protective film, called a slip film, usually a polyamide resin film, is commonly provided be-tween the negative and the photopolymerizable layer in order to prevent the negative from damaging the photo-polymerizable layer.
After the exposure to actinic radiation, the slip film must be removed from the photopolymerizable layer and the uncured material of the photopolymerizable layer must be removed in order to produce the desired relief image or pattern. Typically, a solvent or developer is used which will solvate the portion of the photopolymerizable layer that has not been cured by the actinic radiation, but will not substantially affect the portion of the photo-polymerizable layer which has been cured by the actinic radiation. Typical developers used in such a process are chlorohydrocarbons, such as chloroform, trichloroethylene, tetrachloroethylene or trichloroethylene, either singly or in a mixture with a suitable lower alcohol, such as n-butanol; saturated cyclic or acyclic hydrocarbons, such as petroleum ether, hexane, heptane, octane, cyclohexane or methylcyclohexane; aromatic hydrocarbons, such as benzene, toluene or xylene; or lower aliphatic ketones, such as acetone, methylethyl ketone or methylisobutyl ketone.
In using the prior art developer compositions described above, it usually takes a disadvantageously long time to remove the portion of the photopolymerizable layer which has not been cured. The cured relief patterns or images swell or distort during the washing or removal of the uncured portion of the photopolymerizable layer by the developer composition. Further, under microscopic inspec-tion, the printing surface may exhibit a nonsmooth surface 2i)~ 8~54 due to cracks, crevices, bumps and other surface ir-regularities and this may detrimentally affect the printing quality. Additionally, these prior developers are toxic and must be subjected to special handling procedures and they have low flash points which makes the separation of them from the removed or washed-out, uncured material very difficult.
U.S. Patent No. 4 806 452 discloses a developer com-position which contains, as an essential component, at least one monoterpene and up to 40 % by weight of an ad-ditional solvent.
Flexographic photopolymer printing plates can be made of a variety of different materials, including:
1. block copolymers of styrene and butadiene or styrene and isoprene (U.S. Patent Nos. 4 323 636, 4 323 637, 4 423 135 and 4 369 246), 2. a mixture of nitrile rubber, an addition photo-polymerizable tri- or tetra-unsaturated ester of acrylic or methacrylic acid and an addition polymerization initiator activated by actinic radia-tion (British Patent No. 1358062), 3. a mixture of a high molecular weight butadiene/
acrylonitrile copolymer containing carboxyl groups, a low molecular weight butadiene polymer which may or may not contain carboxyl groups, an ethylenically unsaturated monomer and a free-radical generating system (U.S. Patent No. 4 177 074), and 4. a mixture of a high molecular weight butadiene/
acrylonitrile copolymer containing carboxyl groups, a high molecular weight butadiene/acrylonitrile co-polymer which does not contain carboxyl groups, an ethylenically unsaturated monomer and a free radical generating system (U.S. Patent No. 4 517 279).
21~ ~ ~954 The developer compositions needed for development of these different types of plates vary depending on the specific composition of the plate employed. For example, a de-veloper suitable for the development of Flex-Light type FL-SKOR and Flex-Light type FL-KOR photopolymer plates (regis-tered trademarks of W. R. Grace & Co.) may not be effective in the development of Flex-Light type FL-1 and Flex-Light type FL-AL photopolymer plates (registered trademarks of W.
R. Grace & Co.).
U.S. Patent No. 4 847 182 discloses a developer com-position comprising a terpene which can be blended with a nonsolvent, such as benzyl alcohol, which nonsolvent is effective to promote the spontaneous separation of uncured material from the developer solution after the plate has been developed. Emulsifiers, such as polyethylene glycol mono(nonylphenyl) ethers, can be incorporated in the de-veloper composition so that the plate can be rinsed with water prior to oven drying.
It is an object of the present invention to provide a developer composition for use in the preparation of a relief image or pattern by photopolymerization in which the washout time and the drying time are substantially shorter in comparison with conventional processes, the photo-polymerized relief images or patterns do not undergo sig-nificant permanent distortion or swelling during washout with the developer composition and the developer composi-tion can be economically recovered from the uncured photo-polymerizable material without special handling procedures or explosion problems.
It is a further object of the present invention to provide a developer composition which has a low toxicity 20 1 89~
and volatility, is biodegradable and can be used for de-veloping relief images or patterns produced on a wide variety of types of photopolymer plates.
It is a still further object of the present invention to provide a developer composition which will dissolve the slip film during the development of the plate and thereby eliminate the step of removing the slip film from the photopolymer plate.
It is a still further object of the present invention to provide a developer composition which enables the de-veloped photopolymer plate to be rinsed with plain water thereby eliminating the tackiness produced in the formed image or pattern by the conventional solvent rinses and allowing the easy disposal of waste rinse solution.
SUMMARY OF THE INVENTION
These and other objects of the present invention are accomplished by providing a process and a developer com-position for producing a relief image or pattern on a photopolymerizable layer by removing the uncured portion of the photopolymerizable layer by washing it with a developer composition comprising a monoterpene and N-methyl-pyrrolidone. An aromatic alcohol is employed in the developer composition when a slip film is present on the photopolymerizable layer.
In a second aspect of the present invention, the de-veloper composition is a mixture of a monoterpene, N-methylpyrrolidone, an aromatic alcohol and a nonionic sur-factant. This latter composition is water-rinsable.
DETAILED DESCRIPTION OF THE INVENTION
According to the first, preferred embodiment of the invention, the developer composition of the present inven-tion comprises a monoterpene, N-methylpyrrolidone and an 20 1 89~4 aromatic alcohol. As the monoterpene, p-methane, borneol, menthone, D- and L-limonene, ~-terpineol, ~-terpinene, ~-terpinene, terpinolene, ~-pinene, ~-pinene, ~-pinene, citronellol and mixtures of these monoterpenes can be used.
D-limonene is especially preferred. There can be used D-limonene obtained from orange peel and/or pine needles. D-limonene is nontoxic and has a boiling point of about 175C. The high boiling temperature and vapor pressure of D-limonene enable it to be separated effectively and ef-ficiently from the uncured photopolymerizable material that is dissolved in the developer composition during the wash-out step. The amount of the monoterpene component in the developer composition is from 30 to 60 wt.%, preferably from 35 to 50 wt.%, based on the total weight of the de-veloper composition.
N-methylpyrrolidone is contained in the developer composition, according to the invention, and it is un-expectedly effective to increase the versatility of the developer composition so that a very wide variety of dif-ferent types of photopolymer printing plates can be washed by the developer composition with good results and with improved plate quality. Particularly, the developer com-position can be effectively used in the development of all commercially available flexographic photopolymer printing plates, including Flex-Light type FL-l and Flex-Light type FL-AL acrylic ester photopolymer plates (registered trade-marks of W. R. Grace & Co.) which have heretofore required the use of a developer containing a chlorinated hydro-carbon. The amount of N-methylpyrrolidone present in the invention composition is from 10 to 50 wt.%, preferably from 20 to 40 wt.%, based on the total weight of the de-veloper composition. The amount of N-methylpyrrolidone is 20 1 ~954 less than the amount of the monoterpene component. Prefer-ably, the weight ratio of N-methylpyrrolidone/monoterpene is from about 0.95 to about 0.5, more preferably, from about 0.8 to about 0.6. N-methylpyrrolidone has a boiling point of about 202C so that it has a relatively high flash point and it can be easily separated from the uncured photopolymerizable material.
The aromatic alcohol contained in the developer com-position of the present invention enables the slip film covering the photopolymerizable material to be dissolved during the development step without there being needed a separate step of peeling off the slip film from the photo-polymerizable layer. Of the aromatic alcohols, benzyl alcohol has proven to be particularly effective for dis-solving the slip film without any attendant negative ef-fects on the photopolymerized relief pattern or image. The content of benzyl alcohol is in the developer composition of the present invention in the range of from 1 to 35 wt.%, preferably from about 10 to about 20 wt.%, based on the total weight of the developer composition. The amount of benzyl alcohol is less than the amount of N-methyl-pyrrolidone. Preferably, the weight ratio of N-methyl-pyrrolidone/benzyl alcohol is from 4 to about 1, more preferably about 2.5 to about 1.5. Benzyl alcohol has a boiling point of about 205C and it can be easily separated from the uncured material.
In the event that the photopolymerizable plate does not have a slip film or it is removed in a different way, then the benzyl alcohol can be omitted from the developer com-position.
In a second, preferred embodiment of the present inven-tion, the developer composition additionally comprises a nonionic surfactant. It has been found that the presence 20 1 ~954 of a nonionic surfactant in the developer composition enables the developed photopolymer layer to be rinsed with water before the layer is dried. This reduces the perma-nent distortion or swelling of the developed relief image or pattern during drying. Additionally, the nonionic surfactant emulsifies the ingredients of the developer composition and the uncured material of the photopolymer plate and enables the waste aqueous rinse solution to be sewered or disposed of in another environmentally safe manner. The nonionic surfactant preferably used in the present invention is nonylphenolpolyethylene glycol ethers in which about 6.0 to 9.5 moles of ethylene oxide are condensed with one mole of nonylphenol. It is especially preferred that the nonionic surfactant composition is a blend of nonylphenolpolyethylene (9.5) glycol ether and nonylphenolpolyethylene (6.0) glycol ether in 2:1 weight ratio. The nonionic surfactant is contained in the de-veloper composition of the present invention in an amount of from 5 to 12 wt.%, based on the total weight of the developer composition, preferably about 8 to 10 wt.%.
Preferably, the amount of the nonionic surfacant is less than the amount of benzyl alcohol.
The presently most preferred, water-rinsable developer composition of the present invention consists of 30 wt.% of N-methylpyrrolidone, 50 wt.% of D-limonene, 11 wt.% of benzyl alcohol, 6 wt.% of nonylphenolpolyethylene (9.5) glycol ether and 3 wt.% of nonylphenolpolyethylene (6.0) glycol ether.
The developer composition of the present invention can be used to develop all presently known types of photo-polymer plates, is nontoxic, eliminates the step of remov-ing the slip film and can be more efficiently recovered because of the high temperature and vapor pressure of its 20 ~ 8~4 g components, including the monoterpene. These and other advantages of the present invention are shown in the fol-lowing examples.
In the following examples, the equipment used to per-form the exposure, washing and drying of the photopolymer plates was the Anderson & Vreeland Photopolymer System, commercially available from Anderson & Vreeland, Inc., Bryan, Ohio. The washing equipment was of two types, namely, 1. a 12 inch x 15 inch flat bed for receiving the photopolymer plate and in which a brush is disposed above the plate and is moved in an orbital pattern so that its bristles contact and remove uncured material from the plate, and 2. a 30 inch x 44 inch unit in which the photo-polymer plate is mounted on an oscillatable drum and 4 rotary brushes are disposed in as-sociation with the drum so that their bristles contact and remove uncured material from the plate.
The exposure unit employed W fluorescent-type lamps. When the plate was subjected to "back exposure", that is, uni-form exposure on the back without a negative, the back side of the photopolymer was uniformly cured to a selected depth to form a so-called "floor" underneath the relief areas.
When the plate was subjected to "face exposure", that is, imagewise exposure on the face with a negative, latent relief areas of a selected depth were formed in the face of the photopolymer layer. A W. R. Grace test negative was used. Development of the photopolymer plate with the solution removed the uncured material whereby to form relief areas projecting from the floor. In those cases in which no back exposure and no face exposure were conducted, the test measured the resistance to dissolving of the uncured photopolymer material in the developing solution.
Example 1 A developer solution was prepared by mixing 30 parts by weight of N-methylpyrrolidone, 50 parts by weight of D-limonene, 11 parts by weight of benzyl alcohol, 6 parts by weight of nonylphenolpolyethylene (9.5) glycol ether and 3 parts by weight of nonylphenolpolyethylene (6.0) glycol ether.
The solution was added to a 12 inch x 15 inch,-orbital brush, flat bed plate processor. A photopolymer plate having a photopolymer layer having a thickness of 0.067 inch (KOR~ available from W. R. Grace & Co.) was uniformly pre-exposed on the back for 20 seconds and then was exposed imagewise through a photographic negative placed on the protective layer for 5 minutes and 20 seconds. The plate was then washed with the above-described solution for 4~
minutes in the plate processor. The plate was rinsed with plain tap water and then was dried at 150F for 1 hour.
The depth of the floor (uniformly cured back of the plate) was 0.030 inches. The relief was 0.037 inches deep. The sidewall structure of the image elements was good. Under-mining of the sidewalls and rounding of the edges was not observed.
Additional commercially available photopolymer plates were processed in similar fashion. The following table lists the processing conditions and results. All the tests were conducted with the 12 inch x 15 inch flat bed washing unit.
TM- Trade-mark 20 ~ :89~
TABLE I
Photopoly- Wash- Depth of mer Layer Back Face ing ~ Relief Thickness Expo- Expo- Time Areas Plate Type (inches) sure sure (mins.) (inches) Grace FL-ALr~ 0.067 None None 10 0.031 Grace FL-AL 0.067 None None 12 0.035 DuPont Cyrel LPT~ 0.067 None None 5 0.040 BASFT~ 0.067 None None 4 0.046 DuPont Cyrel LP7~ 0.067 None None 10 O.045 DuPont Cyrel LP 0.067 None None 4 0.042 Grace FL-1~ 0.090 None None 15 0.046 Example 2 A developer solution was prepared by mixing 32 parts by weight of N-methylpyrrolidone, 37 parts of D-limonene, 22 parts of benzyl alcohol and 9 parts of nonylphenolpoly-ethylene/9.S glycol ether.
The solution was added to the 30 inch x 44 inch washing unit described above. The following table lists the pro-cessing results and conditions.
TM - Trade-mark 20 1 ~9 5 4 TABLE II
Photopoly- Wash- Depth of mer Layer Back Face ing Relief Thickness Expo- Expo- Time Areas Plate Type (inches) sure sure (mins.) (inches) FL-Grace KOR 0.067 10 5 6 0.030 secs. mins.
FL-Grace KOR 0.250 5 10 5 0.035 mins. mins.
FL-Grace KOR 0.250 5 10 10 0.070 mins. mins.
FL-Grace KOR 0.250 5 10 15 0.107 mins. mins.
FL-Grace KOR 0.250 5 10 20 0.135 mins. mins.
FL-Grace KOR 0.250None None 20 0.150 DuPont Cyrel LP 0.250 2 10 6 0.040 mins. mins.
Grace FL-l 0.0g0 1~ 8 12 0.030 mins. mlns.
The components of the developer composed can be easily separated from the uncured photopolymer contained therein, for example, by steam distillation or vacuum distillation.
It would be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit there-of, and the invention includes all such modifications.
AND COMPOSITION THEREFOR
BACKGROUND OF THE INVENTION
The present invention relates to an improved method and composition for developing a relief image by imagewise exposing a photopolymerizable layer to actinic radiation and subsequently removing the uncured material of the photopolymerizable layer by use of a developer composition to produce the relief image.
In the following description and claims, the term "cured" and derivatives thereof shall be used to describe material obtained by (1) the photopolymerization of mono-meric or low molecular weight compounds, or (2) the cross-linking of photocrosslinkable polymers. The term "uncured"
and derivatives thereof shall be used to describe material which has not undergone photopolymerization or photocross-linking.
The use of actinic radiation, such as ultraviolet light, to form a relief pattern or image by the imagewise curing of a photopolymerizable layer is well known in the art and is typically used in preparing flexographic print-ing plates and relief patterns on semiconductor layers.
These relief images or patterns are formed by placing an image-bearing process transparency, for example, a line or half-tone negative, over the photopolymerizable layer. The negative is designed to transmit actinic radiation through certain portions of it and to absorb or reflect actinic radiation at other portions so that the photopolymerizable layer underneath the negative is cured imagewise according to the portion of the negative that transmits the radia-tion. A transparent protective film, called a slip film, usually a polyamide resin film, is commonly provided be-tween the negative and the photopolymerizable layer in order to prevent the negative from damaging the photo-polymerizable layer.
After the exposure to actinic radiation, the slip film must be removed from the photopolymerizable layer and the uncured material of the photopolymerizable layer must be removed in order to produce the desired relief image or pattern. Typically, a solvent or developer is used which will solvate the portion of the photopolymerizable layer that has not been cured by the actinic radiation, but will not substantially affect the portion of the photo-polymerizable layer which has been cured by the actinic radiation. Typical developers used in such a process are chlorohydrocarbons, such as chloroform, trichloroethylene, tetrachloroethylene or trichloroethylene, either singly or in a mixture with a suitable lower alcohol, such as n-butanol; saturated cyclic or acyclic hydrocarbons, such as petroleum ether, hexane, heptane, octane, cyclohexane or methylcyclohexane; aromatic hydrocarbons, such as benzene, toluene or xylene; or lower aliphatic ketones, such as acetone, methylethyl ketone or methylisobutyl ketone.
In using the prior art developer compositions described above, it usually takes a disadvantageously long time to remove the portion of the photopolymerizable layer which has not been cured. The cured relief patterns or images swell or distort during the washing or removal of the uncured portion of the photopolymerizable layer by the developer composition. Further, under microscopic inspec-tion, the printing surface may exhibit a nonsmooth surface 2i)~ 8~54 due to cracks, crevices, bumps and other surface ir-regularities and this may detrimentally affect the printing quality. Additionally, these prior developers are toxic and must be subjected to special handling procedures and they have low flash points which makes the separation of them from the removed or washed-out, uncured material very difficult.
U.S. Patent No. 4 806 452 discloses a developer com-position which contains, as an essential component, at least one monoterpene and up to 40 % by weight of an ad-ditional solvent.
Flexographic photopolymer printing plates can be made of a variety of different materials, including:
1. block copolymers of styrene and butadiene or styrene and isoprene (U.S. Patent Nos. 4 323 636, 4 323 637, 4 423 135 and 4 369 246), 2. a mixture of nitrile rubber, an addition photo-polymerizable tri- or tetra-unsaturated ester of acrylic or methacrylic acid and an addition polymerization initiator activated by actinic radia-tion (British Patent No. 1358062), 3. a mixture of a high molecular weight butadiene/
acrylonitrile copolymer containing carboxyl groups, a low molecular weight butadiene polymer which may or may not contain carboxyl groups, an ethylenically unsaturated monomer and a free-radical generating system (U.S. Patent No. 4 177 074), and 4. a mixture of a high molecular weight butadiene/
acrylonitrile copolymer containing carboxyl groups, a high molecular weight butadiene/acrylonitrile co-polymer which does not contain carboxyl groups, an ethylenically unsaturated monomer and a free radical generating system (U.S. Patent No. 4 517 279).
21~ ~ ~954 The developer compositions needed for development of these different types of plates vary depending on the specific composition of the plate employed. For example, a de-veloper suitable for the development of Flex-Light type FL-SKOR and Flex-Light type FL-KOR photopolymer plates (regis-tered trademarks of W. R. Grace & Co.) may not be effective in the development of Flex-Light type FL-1 and Flex-Light type FL-AL photopolymer plates (registered trademarks of W.
R. Grace & Co.).
U.S. Patent No. 4 847 182 discloses a developer com-position comprising a terpene which can be blended with a nonsolvent, such as benzyl alcohol, which nonsolvent is effective to promote the spontaneous separation of uncured material from the developer solution after the plate has been developed. Emulsifiers, such as polyethylene glycol mono(nonylphenyl) ethers, can be incorporated in the de-veloper composition so that the plate can be rinsed with water prior to oven drying.
It is an object of the present invention to provide a developer composition for use in the preparation of a relief image or pattern by photopolymerization in which the washout time and the drying time are substantially shorter in comparison with conventional processes, the photo-polymerized relief images or patterns do not undergo sig-nificant permanent distortion or swelling during washout with the developer composition and the developer composi-tion can be economically recovered from the uncured photo-polymerizable material without special handling procedures or explosion problems.
It is a further object of the present invention to provide a developer composition which has a low toxicity 20 1 89~
and volatility, is biodegradable and can be used for de-veloping relief images or patterns produced on a wide variety of types of photopolymer plates.
It is a still further object of the present invention to provide a developer composition which will dissolve the slip film during the development of the plate and thereby eliminate the step of removing the slip film from the photopolymer plate.
It is a still further object of the present invention to provide a developer composition which enables the de-veloped photopolymer plate to be rinsed with plain water thereby eliminating the tackiness produced in the formed image or pattern by the conventional solvent rinses and allowing the easy disposal of waste rinse solution.
SUMMARY OF THE INVENTION
These and other objects of the present invention are accomplished by providing a process and a developer com-position for producing a relief image or pattern on a photopolymerizable layer by removing the uncured portion of the photopolymerizable layer by washing it with a developer composition comprising a monoterpene and N-methyl-pyrrolidone. An aromatic alcohol is employed in the developer composition when a slip film is present on the photopolymerizable layer.
In a second aspect of the present invention, the de-veloper composition is a mixture of a monoterpene, N-methylpyrrolidone, an aromatic alcohol and a nonionic sur-factant. This latter composition is water-rinsable.
DETAILED DESCRIPTION OF THE INVENTION
According to the first, preferred embodiment of the invention, the developer composition of the present inven-tion comprises a monoterpene, N-methylpyrrolidone and an 20 1 89~4 aromatic alcohol. As the monoterpene, p-methane, borneol, menthone, D- and L-limonene, ~-terpineol, ~-terpinene, ~-terpinene, terpinolene, ~-pinene, ~-pinene, ~-pinene, citronellol and mixtures of these monoterpenes can be used.
D-limonene is especially preferred. There can be used D-limonene obtained from orange peel and/or pine needles. D-limonene is nontoxic and has a boiling point of about 175C. The high boiling temperature and vapor pressure of D-limonene enable it to be separated effectively and ef-ficiently from the uncured photopolymerizable material that is dissolved in the developer composition during the wash-out step. The amount of the monoterpene component in the developer composition is from 30 to 60 wt.%, preferably from 35 to 50 wt.%, based on the total weight of the de-veloper composition.
N-methylpyrrolidone is contained in the developer composition, according to the invention, and it is un-expectedly effective to increase the versatility of the developer composition so that a very wide variety of dif-ferent types of photopolymer printing plates can be washed by the developer composition with good results and with improved plate quality. Particularly, the developer com-position can be effectively used in the development of all commercially available flexographic photopolymer printing plates, including Flex-Light type FL-l and Flex-Light type FL-AL acrylic ester photopolymer plates (registered trade-marks of W. R. Grace & Co.) which have heretofore required the use of a developer containing a chlorinated hydro-carbon. The amount of N-methylpyrrolidone present in the invention composition is from 10 to 50 wt.%, preferably from 20 to 40 wt.%, based on the total weight of the de-veloper composition. The amount of N-methylpyrrolidone is 20 1 ~954 less than the amount of the monoterpene component. Prefer-ably, the weight ratio of N-methylpyrrolidone/monoterpene is from about 0.95 to about 0.5, more preferably, from about 0.8 to about 0.6. N-methylpyrrolidone has a boiling point of about 202C so that it has a relatively high flash point and it can be easily separated from the uncured photopolymerizable material.
The aromatic alcohol contained in the developer com-position of the present invention enables the slip film covering the photopolymerizable material to be dissolved during the development step without there being needed a separate step of peeling off the slip film from the photo-polymerizable layer. Of the aromatic alcohols, benzyl alcohol has proven to be particularly effective for dis-solving the slip film without any attendant negative ef-fects on the photopolymerized relief pattern or image. The content of benzyl alcohol is in the developer composition of the present invention in the range of from 1 to 35 wt.%, preferably from about 10 to about 20 wt.%, based on the total weight of the developer composition. The amount of benzyl alcohol is less than the amount of N-methyl-pyrrolidone. Preferably, the weight ratio of N-methyl-pyrrolidone/benzyl alcohol is from 4 to about 1, more preferably about 2.5 to about 1.5. Benzyl alcohol has a boiling point of about 205C and it can be easily separated from the uncured material.
In the event that the photopolymerizable plate does not have a slip film or it is removed in a different way, then the benzyl alcohol can be omitted from the developer com-position.
In a second, preferred embodiment of the present inven-tion, the developer composition additionally comprises a nonionic surfactant. It has been found that the presence 20 1 ~954 of a nonionic surfactant in the developer composition enables the developed photopolymer layer to be rinsed with water before the layer is dried. This reduces the perma-nent distortion or swelling of the developed relief image or pattern during drying. Additionally, the nonionic surfactant emulsifies the ingredients of the developer composition and the uncured material of the photopolymer plate and enables the waste aqueous rinse solution to be sewered or disposed of in another environmentally safe manner. The nonionic surfactant preferably used in the present invention is nonylphenolpolyethylene glycol ethers in which about 6.0 to 9.5 moles of ethylene oxide are condensed with one mole of nonylphenol. It is especially preferred that the nonionic surfactant composition is a blend of nonylphenolpolyethylene (9.5) glycol ether and nonylphenolpolyethylene (6.0) glycol ether in 2:1 weight ratio. The nonionic surfactant is contained in the de-veloper composition of the present invention in an amount of from 5 to 12 wt.%, based on the total weight of the developer composition, preferably about 8 to 10 wt.%.
Preferably, the amount of the nonionic surfacant is less than the amount of benzyl alcohol.
The presently most preferred, water-rinsable developer composition of the present invention consists of 30 wt.% of N-methylpyrrolidone, 50 wt.% of D-limonene, 11 wt.% of benzyl alcohol, 6 wt.% of nonylphenolpolyethylene (9.5) glycol ether and 3 wt.% of nonylphenolpolyethylene (6.0) glycol ether.
The developer composition of the present invention can be used to develop all presently known types of photo-polymer plates, is nontoxic, eliminates the step of remov-ing the slip film and can be more efficiently recovered because of the high temperature and vapor pressure of its 20 ~ 8~4 g components, including the monoterpene. These and other advantages of the present invention are shown in the fol-lowing examples.
In the following examples, the equipment used to per-form the exposure, washing and drying of the photopolymer plates was the Anderson & Vreeland Photopolymer System, commercially available from Anderson & Vreeland, Inc., Bryan, Ohio. The washing equipment was of two types, namely, 1. a 12 inch x 15 inch flat bed for receiving the photopolymer plate and in which a brush is disposed above the plate and is moved in an orbital pattern so that its bristles contact and remove uncured material from the plate, and 2. a 30 inch x 44 inch unit in which the photo-polymer plate is mounted on an oscillatable drum and 4 rotary brushes are disposed in as-sociation with the drum so that their bristles contact and remove uncured material from the plate.
The exposure unit employed W fluorescent-type lamps. When the plate was subjected to "back exposure", that is, uni-form exposure on the back without a negative, the back side of the photopolymer was uniformly cured to a selected depth to form a so-called "floor" underneath the relief areas.
When the plate was subjected to "face exposure", that is, imagewise exposure on the face with a negative, latent relief areas of a selected depth were formed in the face of the photopolymer layer. A W. R. Grace test negative was used. Development of the photopolymer plate with the solution removed the uncured material whereby to form relief areas projecting from the floor. In those cases in which no back exposure and no face exposure were conducted, the test measured the resistance to dissolving of the uncured photopolymer material in the developing solution.
Example 1 A developer solution was prepared by mixing 30 parts by weight of N-methylpyrrolidone, 50 parts by weight of D-limonene, 11 parts by weight of benzyl alcohol, 6 parts by weight of nonylphenolpolyethylene (9.5) glycol ether and 3 parts by weight of nonylphenolpolyethylene (6.0) glycol ether.
The solution was added to a 12 inch x 15 inch,-orbital brush, flat bed plate processor. A photopolymer plate having a photopolymer layer having a thickness of 0.067 inch (KOR~ available from W. R. Grace & Co.) was uniformly pre-exposed on the back for 20 seconds and then was exposed imagewise through a photographic negative placed on the protective layer for 5 minutes and 20 seconds. The plate was then washed with the above-described solution for 4~
minutes in the plate processor. The plate was rinsed with plain tap water and then was dried at 150F for 1 hour.
The depth of the floor (uniformly cured back of the plate) was 0.030 inches. The relief was 0.037 inches deep. The sidewall structure of the image elements was good. Under-mining of the sidewalls and rounding of the edges was not observed.
Additional commercially available photopolymer plates were processed in similar fashion. The following table lists the processing conditions and results. All the tests were conducted with the 12 inch x 15 inch flat bed washing unit.
TM- Trade-mark 20 ~ :89~
TABLE I
Photopoly- Wash- Depth of mer Layer Back Face ing ~ Relief Thickness Expo- Expo- Time Areas Plate Type (inches) sure sure (mins.) (inches) Grace FL-ALr~ 0.067 None None 10 0.031 Grace FL-AL 0.067 None None 12 0.035 DuPont Cyrel LPT~ 0.067 None None 5 0.040 BASFT~ 0.067 None None 4 0.046 DuPont Cyrel LP7~ 0.067 None None 10 O.045 DuPont Cyrel LP 0.067 None None 4 0.042 Grace FL-1~ 0.090 None None 15 0.046 Example 2 A developer solution was prepared by mixing 32 parts by weight of N-methylpyrrolidone, 37 parts of D-limonene, 22 parts of benzyl alcohol and 9 parts of nonylphenolpoly-ethylene/9.S glycol ether.
The solution was added to the 30 inch x 44 inch washing unit described above. The following table lists the pro-cessing results and conditions.
TM - Trade-mark 20 1 ~9 5 4 TABLE II
Photopoly- Wash- Depth of mer Layer Back Face ing Relief Thickness Expo- Expo- Time Areas Plate Type (inches) sure sure (mins.) (inches) FL-Grace KOR 0.067 10 5 6 0.030 secs. mins.
FL-Grace KOR 0.250 5 10 5 0.035 mins. mins.
FL-Grace KOR 0.250 5 10 10 0.070 mins. mins.
FL-Grace KOR 0.250 5 10 15 0.107 mins. mins.
FL-Grace KOR 0.250 5 10 20 0.135 mins. mins.
FL-Grace KOR 0.250None None 20 0.150 DuPont Cyrel LP 0.250 2 10 6 0.040 mins. mins.
Grace FL-l 0.0g0 1~ 8 12 0.030 mins. mlns.
The components of the developer composed can be easily separated from the uncured photopolymer contained therein, for example, by steam distillation or vacuum distillation.
It would be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit there-of, and the invention includes all such modifications.
Claims (17)
1. A developer composition consisting essentially of from 10 to 60 wt.% of a monoterpene, from 10 to 50 wt.% of N-methylpyrrolidone, from 1 to 35 wt.% of an aromatic alcohol and from 5 to 12 wt.% of a nonionic surfactant, said wt.%
being based on the total weight of the developer composition and the weight ratio of N-methylpyrrolidone/aromatic alcohol being from about 4:1 to about 1:1.
being based on the total weight of the developer composition and the weight ratio of N-methylpyrrolidone/aromatic alcohol being from about 4:1 to about 1:1.
2. The developer composition of claim 1, wherein said monoterpene is d-limonene.
3. The developer composition of claim 2, wherein said d-limonene is obtained from orange peel.
4. The developer composition of claim 2, wherein said d-limonene is obtained from orange peel and pine trees.
5. The developer composition according to claim 2, containing from 35 to 50 wt.% of d-limonene and from 10 to 50 wt.% N-methylpyrrolidone.
6. The developer composition of claim 2, consisting essentially of from 35 to 50 wt.% of d-limonene, from 20 to 40 wt.% of N-methylpyrrolidone, from 10 to 10 wt. % of benzyl alcohol and from 5 to 12 wt.% of nonionic surfactant.
7. The developer composition of claim 6, wherein said nonionic surfactant is nonylphenolpolyethylene (9.5) glycol ether.
8. The developer composition of claim 6, wherein said nonionic surfactant is nonylphenolpolyethylene (6.0) glycol ether.
9. The developer composition of claim 6, wherein said nonionic surfactant is a blend of nonylphenolpolyethylene (9.5) glycol ether and nonylphenolpolyethylene (6.0) glycol ether in a 2:1 weight ratio.
10. The developer composition of claim 6 wherein said nonionic surfactant is selected from the group consisting of ethoxylates of primary alcohol having from 9 to 15 carbon atoms ethoxylated with 5 to 10 moles of ethylene oxide, and mixtures thereof.
11. The developer composition of claim 10, wherein said primary alcohol ethoxylates have a hydrophilic/lipophilic balance number between 7 and 14.
12. The developer composition of claim 1, wherein said aromatic alcohol is benzyl alcohol and the amount of benzyl alcohol is from 10 to 20 wt.%.
13. The developer composition of claim 1, consisting essentially of 20-40 wt.% of N-methylpyrrolidone, 35-50% of d-limonene, 10-20 wt.% of benzyl alcohol and 8-10 wt.% of the nonionic surfactant.
14. The developer composition of claim 13, wherein said nonionic surfactant is a blend of nonylphenolpolyethylene (9.5) glycol ether and nonylphenolpolyethylene (6.0) glycol ether in a 2:1 weight ratio.
15. The developer composition consisting essentially of from 10 to 60 wt.% of a monoterpene, from 10 to 50 wt.% of N-methylpyrrolidone, from 5 to 12 wt.% of a nonionic surfactant, from 10 to 60 wt.% of an organic solvent having an ether-ester functionality and from 0 to 35 wt.% of an aromatic alcohol, said wt.% being based on the total weight of the developer composition and, when the aromatic alcohol is present, the weight ratio of N-methylpyrrolidone/aromatic alcohol being from about 4:1 to about 1:1.
16. The developer composition of claim 15, wherein said aromatic alcohol is benzyl alcohol.
17. The developer composition of claim 15, consisting essentially of 20 wt.% of N-methylpyrrolidone, 46 wt.% of d-limonene, 0-6 wt.% of benzyl alcohol, 4 wt.% of nonylphenolpolyethylene (9.5) glycol ether, 4 wt.% of -nonylphenolpolyethylene (6.0) glycol ether and 20-26 wt.% of ethyl-3-ethoxypropionate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52189790A | 1990-05-10 | 1990-05-10 | |
| US521,897 | 1990-05-10 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2018954A1 CA2018954A1 (en) | 1991-11-10 |
| CA2018954C true CA2018954C (en) | 1995-12-19 |
Family
ID=24078596
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2018954 Expired - Fee Related CA2018954C (en) | 1990-05-10 | 1990-06-13 | Method of developing photopolymerizable printing plates and composition therefor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2018954C (en) |
-
1990
- 1990-06-13 CA CA 2018954 patent/CA2018954C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2018954A1 (en) | 1991-11-10 |
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