U.S. patent application number 09/993912 was filed with the patent office on 2003-06-05 for developing solvent for photopolymerizable printing plates.
Invention is credited to Bradford, David Calvin, Hendrickson, Constance Marie.
Application Number | 20030104315 09/993912 |
Document ID | / |
Family ID | 25540063 |
Filed Date | 2003-06-05 |
United States Patent
Application |
20030104315 |
Kind Code |
A1 |
Hendrickson, Constance Marie ;
et al. |
June 5, 2003 |
DEVELOPING SOLVENT FOR PHOTOPOLYMERIZABLE PRINTING PLATES
Abstract
Flexographic printing plates are produced by exposing the
photopolymer plates to a light source and washing out (developing)
the masked out, non-exposed areas with a solvent. The invention
provides methyl ester solvents suitable for use in the development
of photopolymer printing plates. The solvents, which include methyl
esters alone or mixed with co-solvents and/or non-solvents, are
effective in developing a large number of different photopolymer
printing plates and can produce images superior to those obtained
with commercially available solvents currently used in such
applications.
Inventors: |
Hendrickson, Constance Marie;
(Irving, TX) ; Bradford, David Calvin; (Winston
Salem, NC) |
Correspondence
Address: |
BLANK ROME COMISKY & MCCAULEY, LLP
900 17TH STREET, N.W., SUITE 1000
WASHINGTON
DC
20006
US
|
Family ID: |
25540063 |
Appl. No.: |
09/993912 |
Filed: |
November 27, 2001 |
Current U.S.
Class: |
430/294 ;
430/309; 430/331 |
Current CPC
Class: |
G03F 7/325 20130101 |
Class at
Publication: |
430/294 ;
430/309; 430/331 |
International
Class: |
G03F 007/32 |
Claims
What is claimed is
1. A method for the development of photopolymerizable flexographic
relief printing plates comprising selecting a developing solvent,
said developing solvent comprising at least one methyl ester; and
washing an exposed flexographic relief printing plate with said
developing solvent to develop and image by dissolving and washing
away non-exposed photopolymerizable material.
2. The method of claim 1, wherein the photopolymerizable
flexographic relief printing plates is selected from the group
consisting of block co-polymers of styrene and butadiene, block
co-polymers of styrene and isoprene, co-polymers of butadiene and
acrylonitrile, terpolymers of butadiene, acrylonitrile, and acrylic
acid.
3. The method of claim 1, wherein the methyl ester is methyl ester
of fatty acids with 8-18 carbons.
4. The method of claim 1, wherein the developing solvent further
comprising a co-solvent.
5. The method of claim 4, wherein the co-solvent is selected from
the group consisting of n-butanol, 2-ethoxyethanol, benzyl alcohol,
ethanol, methanol, propanol, isopropanol, alpha terpineol,
dipropylene glycol methyl ether, 2-butoxyethanol, isopropyl
alcohol, and 2-(2-butoxyethoxy) ethanol, cyclopentanol,
cyclohexanol, cycloheptanol, substituted cyclopentanol, substituted
cyclohexanol, substituted cycloheptanol, cyclopentyl substituted
alcohol, cyclohexyl substituted alcohol, and cycloheptyl
substituted alcohol.
6. The method of claim 5, wherein the substituted cyclohexanol is
4-ethycyclohexanol.
7. The method of claim 5, wherein the substituted cyclopentanol is
2,3 dimethylcyclopentanol.
8. The method of claim 5, wherein the cyclohexyl substituted
alcohol is cyclohexylpropanol.
9. The method of claim 5, wherein the cyclopentyl substituted
alcohol is 4-cyclopentylpentanol.
10. The method of claim 1, wherein the developing solvent further
comprising a non-solvent.
11. The method of claim 10, wherein the non-solvent is selected
from the group consisting of aliphatic petroleum distillates,
naphthas, paraffinic solvents, hydro-treated petroleum distillates,
mineral oil, mineral spirits, ligroin, decane, octane, and
hexane.
12. The method of claim 1, wherein the developing solvent further
comprising a co-solvent and a non-solvent.
13. The method of claim 12, wherein the co-solvent is selected from
the group consisting of n-butanol, 2-ethoxyethanol, benzyl alcohol,
ethanol, methanol, propanol, isopropanol, alpha terpineol,
dipropylene glycol methyl ether, 2-butoxyethanol, isopropyl
alcohol, and 2-(2-butoxyethoxy) ethanol, cyclopentanol,
cyclohexanol, cycloheptanol, substituted cyclopentanol, substituted
cyclohexanol, substituted cycloheptanol, cyclopentyl substituted
alcohol, cyclohexyl substituted alcohol, and cycloheptyl
substituted alcohol.
14. The method of claim 12, wherein the non-solvent is selected
from the group consisting of aliphatic petroleum distillates,
naphthas, paraffinic solvents, hydro-treated petroleum distillates,
mineral oil, mineral spirits, ligroin, decane, octane, and
hexane.
15. The method of claim 12, wherein the methyl ester is present in
an amount of about 50-70% by volume, the co-solvent is present in
an amount of about 20-50% by volume, and the non-solvent is present
in an amount of about 10-30% by volume.
16. The method of claim 1, further comprising drying the
flexographic relief printing plate to remove the developing
solvent.
17. A developing solvent for the development of photopolymerizable
flexographic relief printing plates comprising at least one methyl
ester effective to remove non-exposed photopolymerizable
material.
18. The developing solvent of claim 17, wherein the methyl ester is
methyl ester of fatty acids with 8-18 carbons.
19. The developing solvent of claim 17, wherein the developing
solvent further comprising a co-solvent.
20. The developing solvent of claim 19, wherein the co-solvent is
selected from the group consisting of n-butanol, 2-ethoxyethanol,
benzyl alcohol, ethanol, methanol, propanol, isopropanol, alpha
terpineol, dipropylene glycol methyl ether, 2-butoxyethanol,
isopropyl alcohol, and 2-(2-butoxyethoxy) ethanol, cyclopentanol,
cyclohexanol, cycloheptanol, substituted cyclopentanol, substituted
cyclohexanol, substituted cycloheptanol, cyclopentyl substituted
alcohol, cyclohexyl substituted alcohol, and cycloheptyl
substituted alcohol.
21. The developing solvent of claim 20, wherein the substituted
cyclohexanol is 4-ethycyclohexanol.
22. The developing solvent of claim 20, wherein the substituted
cyclopentanol is 2,3 dimethylcyclopentanol.
23. The developing solvent of claim 20, wherein the cyclohexyl
substituted alcohol is cyclohexylpropanol.
24. The developing solvent of claim 20, wherein the cyclopentyl
substituted alcohol is 4-cyclopentylpentanol.
25. The developing solvent of claim 17, further comprising a
non-solvent.
26. The developing solvent of claim 25, wherein the non-solvent is
selected from the group consisting of aliphatic petroleum
distillates, naphthas, paraffinic solvents, hydro-treated petroleum
distillates, mineral oil, mineral spirits, ligroin, decane, octane,
and hexane.
27. The developing solvent of claim 17, further comprising a
co-solvent and a non-solvent.
28. The developing solvent of claim 27, wherein the co-solvent is
selected from the group consisting of n-butanol, 2-ethoxyethanol,
benzyl alcohol, ethanol, methanol, propanol, isopropanol, alpha
terpineol, dipropylene glycol methyl ether, 2-butoxyethanol,
isopropyl alcohol, and 2-(2-butoxyethoxy) ethanol, cyclopentanol,
cyclohexanol, cycloheptanol, substituted cyclopentanol, substituted
cyclohexanol, substituted cycloheptanaol, cyclopentyl substituted
alcohol, cyclohexyl substituted alcohol, and cycloheptyl
substituted alcohol.
29. The developing solvent of claim 27, wherein the non-solvent is
selected from the group consisting of aliphatic petroleum
distillates, naphthas, paraffinic solvents, hydro-treated petroleum
distillates, mineral oil, mineral spirits, ligroin, decane, octane,
and hexane.
30. The developing solvent of claim 27, wherein the methyl ester is
present in an amount of about 50-70% by volume, the co-solvent is
present in an amount of about 20-50% by volume, and the non-solvent
is present in an amount of about 10-30% by volume.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an improved solvent and
process for the production of flexographic printing plates
crosslinked by photopolymerization. More specifically, the
invention relates to a solvent system using methyl esters, alone or
in combination with co-solvents and/or non-solvents, as washout
solvents for the unpolymerized material in the printing plates to
develop a relief image and a method for developing printing
plates.
BACKGROUND OF THE INVENTION
[0002] Washout processes for the development of photopolymerizable
flexographic printing plates are well known and is described in
detail in U.S. Pat. No. 5,240,815 which is incorporated herein by
reference. Ordinarily, exposed plates are washed (developed) in a
developing solvent that can remove the unpolymerized material while
leaving the polymerized (cured) material intact. The solvent
typically used in such processes include: (a) chlorohydrocarbons,
such as trichloroethylene, perchloroethylene or trichloroethane,
alone or in a mixture with a lower alcohol, such as n-butanol; (b)
saturated cyclic or acyclic hydrocarbons, such as petroleum ether,
hexane, heptane, octane, cyclohexane or methylcyclohexane; (c)
aromatic hydrocarbons, such as benzene, toluene or xylene; (d)
lower aliphatic ketones, such as acetone, methyl ethyl ketone or
methyl isobutyl ketone; and (e) terpene hydrocarbons, such as
d-limonene.
[0003] One important disadvantage of the known solvents and the
procedures for their use is that the solvents being used as
developers may act too slowly, cause swelling of the plates and/or
cause damage to the fine detail in the plate by undercutting and/or
pinholing. Moreover, when non-chlorinated solvents are used in the
washout process, long drying times may be necessary. Furthermore,
many of these solvents have flashpoints of less than 100.degree.
F., so that the process can only be operated in special,
explosion-protected plants. Many of the prior art solvents are
considered Hazardous Air Pollutants (HAPS), and are subject to
stringent reporting requirements. When chlorohydrocarbons and other
toxic chemicals are used, their toxicity also gives rise to
disposal problems and worker safety issues.
[0004] An essential step to any photopolymerizable relief printing
process is the development of the printing plate after the image is
formed through imagewise exposure of the photopolymerizable plate
to light. The image is formed by polymerizing and crosslinking of
the photopolimerizable material that is exposed while the unexposed
portion remains unpolymerized. Ordinarily, development is
accomplished by washing the exposed plate in a solvent which can
remove the unpolymerized material while leaving the polymerized
(cured) material intact. Since such plates can be formed from a
variety of materials, it is necessary to match a specific plate
with an appropriate solvent. For example, U.S. Pat. No. 4,323,636,
U.S. Pat. No. 4,323,637, U.S. Pat. No. 4,423,135, and U.S. Pat. No.
4,369,246, the disclosures of which are incorporated herein by
reference, disclose a variety of photopolymer printing plate
compositions based on block copolymers of styrene and butadiene
(SBS) or isoprene (SIS). These compositions can be utilized to
produce printing plates which can be developed by a number of
aliphatic and aromatic solvents, including methyl ethyl ketone,
toluene, xylene, d-limonene, carbon tetrachloride, trichloroethane,
methyl chloroform, and tetrachloroethylene. These solvents may be
used alone or in a mixture with a "non-solvent" (i.e. a substance
that cannot dissolve unpolymerized materials), for example,
trichloroethane with ethanol. In any case, during the development
step, the solvent can be applied in any convenient manner such as
by pouring, immersing, spraying, or roller application. Brushing,
which aids in the removal of the unpolymerized or uncrosslinked
portions of the composition, can also be performed to facilitate
the processing of the plate.
[0005] Similarly, UK 1,358,062 discloses photosensitive
compositions consisting of a nitrile rubber with an addition of
photopolymerizable tri- or tetra-unsaturated ester derived from
acrylic or methacrylic acid combined with an addition
polymerization initiator activated by actinic radiation. Plates
made from this composition can be developed by organic solvents
including aliphatic esters such as ethyl acetate, aliphatic ketones
such as acetone, methyl ethyl ketone, d-limonene, halogenated
organic solvents, such as chloroform, methylene chloride, CFC 113
or blends of such solvents. Brushing or agitation can be used to
facilitate the removal of the non-polymerized portion of the
composition.
[0006] U.S. Pat. No. 4,177,074 discloses a photosensitive
composition containing a high molecular weight
butadiene/acrylonitrile copolymer which contains carboxyl groups, a
low molecular weight butadiene polymer which may or may not contain
carboxyl groups, and an ethylenically unsaturated monomer, combined
with a free-radical generating system. This composition is also
used as the polymer layer of a flexographic printing plate and
requires processing with such organic solvents as methyl ethyl
ketone, benzene, toluene, xylene, d-limonene, trichloroethane,
trichlorethylene, methyl chloroform, tetrachloroethylene, or
solvent/non-solvent mixtures, e.g., tetrachloroethylene and
n-butanol. The composition may also be processed with water-soluble
organic solvents in an aqueous basic solution, such as sodium
hydroxide/isopropyl alcohol/water; sodium carbonate/isopropyl
alcohol/water; sodium carbonate/2-butoxyethanol/water; sodium
borate/2-butoxyethanol/water; sodium
silicate/2-butoxyethanol/water; sodium borate/2-butoxyethanol/wate-
r; sodium silicate/2-butoxyethanol/glycerol/water; and sodium
carbonate/2-(2-butoxyethoxy)ethanol/water.
[0007] U.S. Pat. No. 4,517,279, the disclosure of which is
incorporated herein by reference, discloses a photosensitive
composition containing a high molecular weight butadiene
acrylonitrile copolymer which contains carboxyl groups, and a high
molecular weight butadiene/acrylonitrile copolymer which does not
contain carboxyl groups, combined with ethylenically unsaturated
monomer and a free radical generating system. That composition,
which is also used as the polymer layer of a flexographic printing
plate, requires processing by blends of tetrachloroethylene and a
non-solvent. The composition may also be processed in mixtures of
sodium hydroxide/isopropyl alcohol/water; sodium
carbonate/2-butoxyethanol/water; sodium
silicate/2-butoxyethanol/water; sodium
carbonate/2-butoxyethanol/glycerol/water; and sodium
hydroxide/2-(2-butoxyethoxy)ethanol/water.
[0008] As can be seen from the foregoing examples of the prior art,
the solvents needed for image development will vary depending on
the composition of the polymer layer of the plate. The need for
different solvent systems is particularly inconvenient, especially
if different photopolymer systems are being processed at the same
facility. Furthermore, many of the solvents used to develop the
plates are toxic or suspected carcinogens. Thus, there exists a
real need for solvent systems which can be used with a greater
degree of safety. In addition, there exists a need for solvent
systems which can be used in a variety of plates. U.S. Pat. No.
4,806,452 and U.S. Pat. No. 4,847,182, the disclosures of which are
incorporated herein by reference, disclose solvent developers for
flexographic plates containing terpene hydrocarbons such as
d-limonene which are effective on a variety of plate types. These
terpene hydrocarbon-based developers are also non-toxic. However,
they have proven to be hazards in the workplace because of their
tendency to spontaneously combust thereby causing fires.
[0009] Therefore, commonly assigned U.S. Pat. No. 6,248,502 solves
the drawbacks of terpene by using terpene esters as a substitute
developing solvent. Because terpene ester has a higher flash point,
the fire risk is greatly decreased. However, terpene esters tends
to breakdown through repeated distillation which limits the
recyclability of the solvent.
[0010] The present invention relates to an environmentally friendly
developing solvent that offers improvement over the prior art. The
solvent comprises methyl esters which have higher flash points when
compared to current solvents. For example, d-limonene (a terpene),
terpene ester, and methyl ester have a flash points of 120.degree.
F., 141.degree. F., and>250.degree. F., respectively. By having
a high flash point, methyl esters offers superior safety in
addition to low toxicity, reduced cost, and biodegradability.
Furthermore, compared developing solvents of the prior art
including terpene ester, methyl ester causes less plate swelling.
Therefore, more methyl esters (up to 70 % by volume) can be used in
the developing solvent resulting in faster removal rate of the
non-polymerized portion of the plate.
SUMMARY OF THE INVENTION
[0011] The present invention comprises solvents for use in the
processing of a wide variety of photopolymeric materials used to
form photopolymer printing plates. These solvents, which comprise
methyl esters either alone or in the presence of other organic
materials (co-solvents and non-solvents), can be used with a
variety of polymeric systems. The methyl esters are natural
products with low toxicity and are relatively safe to use compared
with other solvent systems. Methyl esters, it has been discovered,
provide a unique combination of reduced cost, improved plate
quality, low volatility, improved regulatory compliance, low
toxicity, reduced washout time, and biodegradability.
[0012] It is, therefore, an object of the present invention to
provide a solvent system and a process for the preparation of
relief plates crosslinked by photopolymerization, in which the
washout time and the drying time are substantially shorter compared
with the conventional process solvents, and wherein the relief
plates suffer neither excessive surface swelling nor under-washing
and are characterized by improved relief depths and sidewall
structure.
[0013] Another object of the present invention is to provide a
process for the preparation of relief plates crosslinked by
photopolymerization which is capable of operation without expensive
explosion protection.
[0014] It is another object of the present invention to provide
solvent systems for use with photopolymeric printing plates which
overcome the spontaneous combustion problems of the prior art
solvent systems.
[0015] It is another object of the present invention is to provide
solvent systems which minimizes workplace hazards and requires
minimal regulatory reporting.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The present invention comprises methyl ester solvents for
use in photopolymer printing plate processing. The methyl esters,
which can be used either alone or in a blended form with
co-solvents or non-solvents, can be used to develop a number of
different photopolymer printing plates. As used herein, co-solvents
are non-methyl ester compounds that can also dissolve the
non-polymerized material; and non-solvents are compounds that
cannot dissolve the non-polymerized material. Methyl esters has the
general formula RCOOCH.sub.3, where R can be any organic moiety. A
wide variety of methyl esters are suitable for use in the solvents
of this invention including, but not limited to, methyl esters of
fatty acids with 8-18 carbons.
[0017] Mixtures of methyl esters can also be used and may show
synergistic effects when compared with a methyl ester used alone.
When a combination of two or more methyl esters is used, the
resulting blend is often more effective as a solvent than the
individual methyl esters. This blend is referred to herein as a MME
(Methyl Mixed Ester) solvent.
[0018] Various co-solvents (non-methyl ester compounds that can
also, by themselves, dissolve the non-polymerized material) and
non-solvents (compounds that cannot, by themselves, dissolve the
non-polymerized material) can also be employed with the methyl
esters and MME according to the invention. Suitable co-solvents
include, but is not limited to, n-butanol, 2-ethoxyethanol, benzyl
alcohol, ethanol, methanol, propanol, isopropanol, alpha terpineol,
dipropylene glycol methyl ether, 2-butoxyethanol, isopropyl
alcohol, and 2-(2-butoxyethoxy) ethanol, cyclopentanol,
cyclohexanol, cycloheptanol, substituted cyclopentanol, substituted
cyclohexanol, substituted cycloheptanol, cyclopentyl substituted
alcohol, cyclohexyl substituted alcohol, and cycloheptyl
substituted alcohol.
[0019] The co-solvent should be soluble in the methyl ester or MME,
should have suitable dissolving properties towards the
non-photolysed (non-polymerized) portions of the plate that are to
be dissolved, should have low toxicity and acceptable safety
profiles, and should be readily disposable. The co-solvents are
used to modify the properties of the solvent blend. This includes,
for example, the addition of co-solvents to aid in the removal of
the top protective cover skin on the flexographic plate. In
addition, several of the co-solvents, such as terpene alcohols, in
particular alpha terpineol, serve as stabilizers to prevent the
separation of the solvent blend, which can occur at reduced
temperatures. This stabilizer property of the co-solvent becomes
important when isoparaffinic hydrocarbons are used as the
non-solvent and benzyl alcohol is used as a co-solvent to remove
the outer layer of the photopolymerizable printing plate since the
benzyl alcohol may separate from the methyl esters and paraffinic
hydrocarbon mixture. Further, the mixture of methyl esters and
co-solvent is often more effective as a solvent than the individual
methyl esters by itself.
[0020] The non-solvent should be miscible with the methyl ester or
methyl esters and the co-solvents, should have acceptable toxicity
and safety profiles, and should be readily disposable or
recyclable. The non-solvent are typically used as a filler to
reduce cost, therefore, recyclability of the non-solvent material
is highly desirable. Suitable non-solvents include, but is not
limited to, petroleum distillates, such as aliphatic petroleum
distillates, naphthas, paraffinic solvents, hydrotreated petroleum
distillates, mineral oil, mineral spirits, ligroin, decane, octane,
hexane and other similar materials. Isoparaffinic solvents are
commercially available in a wide range of volatility and
corresponding flash points. The developing solvent of the invention
can made with a wide range of commercially available isoparaffinic
solvents as its non-solvent base. The following table shows
volatilities and properties of commercially available isoparaffinic
solvents suitable for use with the invention.
1TABLE 1 Volatility Flash Point (.degree. F.) 106 129 135 147 196
Initial Boiling Point (.degree. F.) 320 352 350 376 433 50% Dry
Point (.degree. F.) 331 360 365 383 460 345 370 386 405 487 Vapor
Pressure (mm Hg @ 100.degree. F.) 14 6.2 5.7 5.2 3.1
[0021] Parameters such as drying rates, fire risk, workplace air
quality and volatile organic compound emissions will also play a
role in the selected non-solvent choice.
[0022] In addition, in a commercially acceptable product, odor
masking materials or perfumes are often added. Such odor masking
materials or perfumes can include terpenes to impart a clean, fresh
odor.
[0023] The developing solvent components can be varied but a
suitable composition would be about 30-75% by volume of at least
one methyl ester and preferably a mixture of methyl esters, about
20-60% by volume of a first co-solvent capable of dissolving the
top protective cover layer of the flexographic plate, about 5-35%
by volume of a second co-solvent. Optionally less than about 2% by
volume of a perfume or odor masking material can be added to the
solvent; however, it is important that the perfume must not
adversely affect the function of the solvent. A non-solvent can
also be included in the solvent in an amount up to about 45% by
volume. A preferred composition would be about 50-70% by volume of
at least one methyl ester and preferably a mixture of methyl
esters, about 20-50% by volume of a first co-solvent capable of
dissolving the top protective cover layer of the flexographic
plate, about 10-30% by volume of a second co-solvent. A non-solvent
can also be included in the preferred mixture in an amount up to
about 20% by volume. The preferred co-solvents are 2-ethylhexanol
and cyclohexanol; and the preferred non-solvent is an isoparaffinic
hydrocarbon. An especially preferred developing solvent comprises
70% methyl hexadecanoate, 20% 2-ethylhexanol, and 10%
cyclohexanol.
[0024] The methyl ester-based solvents may be substituted for the
synthetic hydrocarbon, oxygenated solvents or halogenated
hydrocarbon solvents used for processing photopolymer printing
plates. For example, the methyl ester solvents are suitable in the
processing of photopolymer printing plates based on block
copolymers of styrene and butadiene (SBS) or styrene and isoprene
(SIS), copolymers of butadiene and acrylonitrile, terpolymers of
butadiene, acrylonitrile and acrylic acid and other similar
photopolymers. The methyl ester-based solvents can be applied to
the plates by any conventional application means including
spraying, brushing, rolling, dipping (immersing) or any combination
thereof. The methyl ester solvents also produce photopolymer plates
with less cured polymer image swelling than those processed in
conventional hydrocarbon or chlorinated hydrocarbon solvents. Since
swelling tends to distort the image formed, this surprising result
permits clear, sharp images to be formed at much lower exposure
times than those resulting from the use of conventional solvents.
Additionally, the solvents of the invention have fairly low
volatility which reduces worker exposure during plate processing.
Furthermore, because methyl esters are natural products, they are
much less toxic and are more readily biodegradable than synthetic
hydrocarbon or chlorinated hydrocarbon solvents.
[0025] The following examples are given to illustrate the present
invention. It should be understood that the invention is not to be
limited to the specific conditions or details described in these
examples.
EXAMPLE 1
Plate Preparation
[0026] Plates were made of Dupont 112 TDR, a photopolymerizable
material. The plate sizes are as follows: plate #1) 24".times.52",
plate #2) 27".times.42", and plate #3) 50".times.55". Each plate
was exposed on the backside for 95 seconds and on the front for 700
seconds.
EXAMPLE 2
Development
[0027] The plates were developed using a solvent blend of about 70%
of methyl hexadecanoate, 20% 2-ethylhexanol, and 10% cyclohexanol.
The plates were processed at 50 mm per minute processor speed for
plates #1 and #2 and 85 mm per minute for plate #2, and at brush
pressure of 1 mm down pressure for all three plates.
EXAMPLE 3
Swell and Dry Times
[0028] The following tables gave the face and floor thickness of
each plate after development with the developer of Example 2 (all
measurements were given in {fraction (1/1000)} inch). The plates
measurements were checked at random locations on the plate. The
plates were dried to the correct gauge for the plate before final
measurements were taken.
2TABLE 2 Plate #1 After 15 min. in After 40 min. in Just before
drying plate dryer plate dryer Face Floor Face Floor Face Floor
0.118 0.056 0.115 0.052 0.114 0.042 0.117 0.056 0.114 0.040 0.113
0.030 0.118 0.048 0.114 0.036 0.113 0.037 0.117 0.034 0.117 0.043
0.115 0.038 0.117 0.040 0.116 0.049 0.112 0.046 Average 0.1174
.0468 0.1152 0.0440 0.1134 0.0386
[0029]
3TABLE 3 Plate #2 Just before drying After 60 min. in plate dryer
Face Floor Face Floor 0.118 0.063 0.112 0.049 0.118 0.057 0.112
0.044 0.118 0.046 0.112 0.036 0.118 0.043 0.112 0.030 0.118 0.060
0.113 0.034 -- -- 0.113 0.041 Average 0.1180 0.538 0.1123
0.0390
[0030]
4TABLE 4 Plate #3 Just before drying After 60 min. in plate dryer
Face Floor Face Floor 0.116 0.062 0.114 0.049 0.115 0.056 0.113
0.044 0.115 0.040 0.113 0.036 0.115 0.043 0.112 0.030 0.116 0.046
0.112 0.034 -- -- 0.113 0.041 Average 0.1154 0.0494 0.1128
0.0390
[0031] The data clearly showed faster drying times when compared to
developing solvents of the prior art. The drying times using the
methyl ester solvent of Example 2 were less than 60 minutes while
typical drying times of prior art solvents were about 90 to 180
minutes. For example, the drying times of the terpene ester solvent
disclosed in U.S. Pat. No. 6,248,502 were from 70 to 160
minutes.
[0032] The invention has been disclosed broadly and illustrated in
reference to representative embodiments described above. Those
skilled in the art will recognize that various modifications can be
made to the present invention without departing from the spirit and
scope thereof.
* * * * *