JPH0146870B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Traditionally, liquid photopolymer printing plate blanks have been developed, such as those illustrated in U.S. Pat. No. 3,597,080, which generally describes current commercial embodiments. have been formed by dispensing a puddle of photopolymer in front of a doctor blade that spreads and shapes the polymer.

Current photopolymer printing plates are rectangular;
In the past, it has been very difficult to maintain perfect reproducibility of shape when forming liquid photopolymer printing plate blanks with straight edges.
The top and bottom edges of the sheet laydown, especially the bottom edge, tended to curl inward or flare outward rather than being straight. That is, it is difficult to form straight edges of the sheet with the polymer material at the beginning and end of forming each sheet, and it is impossible to form a rectangular sheet with straight sides. Therefore, in order to ensure that the thickness of the viscous liquid printing plate blank is uniform and large enough to be within the length and width specifications, it is necessary to add an additional border, which Even if most of the excess is recycled, the polymer is wasted. Additionally, it was necessary to continually readjust and fine-tune the dispensing and shaping equipment during the day of operation to maintain reasonable uniformity of size within the required thickness specifications.

Therefore, one of the objectives of the present invention is to prevent waste of polymer.

Another object of the invention is to increase the quality of the printing plate blanks produced and thereby the quality of the printing plates produced.

Another object of the invention is to save effort in adjusting and operating the device.

Furthermore, another object of the invention is to increase the production rate of printing plates and increase the number of blanks that can be produced per hour.

Another object of the invention is to produce a device that is cheaper and simpler to construct, maintain and operate than devices previously used.

According to one aspect of the invention, there is provided a method of forming a printing plate, the method comprising dispensing and shaping a liquid one after another to form a series of substantially rectangular sheets, the method comprising: (a) supplying liquid to a dispensing reservoir to a predetermined depth and maintaining said depth; (b) intermittently opening and closing a valve means to cause liquid to drain from said reservoir by gravity; (c) supplying the liquid from the reservoir through each of the plurality of capillary tubes to the inlet of the manifold and maintaining the capillary tubes in a substantially liquid-filled state at all times during the successive operations; (d) opening from the capillary tubes; supplying the liquid through the inlets along a linearly aligned path into a hollow manifold having a surface having a flat surface, and intermittently interrupting the flow of liquid into the manifold from all of the inlets; e) restricting the flow of liquid from the manifold by a dam formed by the edge of one of the open faces of the manifold; (f) supplying the manifold with liquid through a capillary tube such that the contents of the manifold are intermittently The liquid is allowed to flow from the outside edge of the open side of the manifold opposite that edge until emptied, limiting the height of the liquid flowing out to a height below the inside height of the manifold. (g) flattening the liquid flowing from the outwardly open portion of the manifold by doctor means, thereby providing a substantially rectangular sheet of liquid; The liquid photopolymer printing plate blank is exposed to actinic radiation through the masking material for a sufficient time to solidify the radiation-curable composition in the exposed areas. Thereafter, the unexposed radiation-curable composition is removed to form a printing plate, which is placed in a printing press and printing begins.

According to another aspect of the invention, an apparatus for producing liquid photopolymer printing plate blanks is provided. The device is a liquid dispensing and shaping device for dispensing substantially rectangular liquid reservoirs in discontinuous succession, the device comprising: an elongated linearly aligned manifold having an inlet with an open surface, one linear edge of the open face of the manifold and at least a portion of the two ends forming a dam; (b) a doctor blade cooperating with the opposite edge of the manifold that is open to the outside at a height below the uppermost extremity of the manifold; (c) supplying liquid to and remaining open to each inlet of the manifold;
a plurality of capillaries which remain filled with liquid during successive operations of the liquid dispensing and shaping device; (d) a plurality of supply outlets supplying liquid to each of the capillaries; (e) a plurality of supply outlets; (f) a gravity feed liquid distribution reservoir for supplying liquid to said plurality of feed outlets; (g) ) reservoir liquid level detection and control means for maintaining the liquid level in the reservoir at a predetermined liquid head; only the liquid head provides liquid pressure to the manifold at the inlet; It is characterized by The dam is preferably spaced a distance from the working surface, the distance being such that when the manifold and the dam move at 1 inch/second in the direction in which the dam is disposed with respect to the manifold, 4120721
This is such as to prevent substantial extrusion of a polyurethane acrylate-based photopolymer liquid adjusted to a viscosity of 2000 cps, as described in the Examples of that issue.

Referring to FIGS. 1 and 3, a liquid dispensing and shaping apparatus 10 is shown. The apparatus includes a platen 11 and an associated carriage 12 that moves over the platen surface. The carriage and platen are coupled together by suitable frame members (not shown). The carriage supports an elongate member 13 that includes a manifold 14 (see also FIG. 2). Manifold 14 has a plurality of inlets 15 aligned along its length.
The manifold is machined from a single piece of metal and has an open semi-cylindrical groove on one side and an inlet 15 on the opposite side. One edge 16 of the semi-cylindrical groove forms a dam and the other side of the semi-cylindrical groove is open outward towards the platen. The platen works with a dam to prevent leakage from the manifold.

Member 13 has an integral doctor blade 17 machined from the same single piece of metal as manifold 14. The doctor blade is elongated and aligned with manifold 14 and has dams 18a and 1 at each respective end integral with the dam formed by the edge of the semi-cylindrical groove of manifold 14.
It has 8b. The manifold 14 is supplied with liquid from the inlet 15 via a capillary tube 19, and the capillary tube 19 is connected to the supply outlet 2 of a distribution reservoir 21 of the feed liquid.
connected to 0. Note that the supply liquid distribution reservoir can also be a liquid supply manifold. A single rod member 22 having a valve means 23 can be operated to seal the supply outlet 20 of the distribution reservoir 21 when it is desired to stop the supply of polymer. The single bar member 22 is a sealing actuating shaft 24
It is operated by the movement of. The movement of the carriage 12 and the operation of the seal actuation shaft 24 can be interconnected by suitable power sequencing means in a manner well known to those skilled in the art.

Delivery reservoir 21 is preferably maintained at a constant head to provide a constant, controlled gravity flow through manifold 14. In this regard, the liquid level detection and control means 25, illustrated as a float, can be interconnected with a large feeder (not shown). The feeder can supply liquid via one or more flexible hoses 26 to maintain the water head at a substantially uniform height in the distribution reservoir 21. Rod heater 2
Heaters such as those shown as 7a, 27b and 27c can be installed to maintain the viscosity of the photopolymer at a predetermined value.

In the normal case, the platen 11 and the elongate member 13 will be arranged such that an intermediate support 29 for the printing plate blank is placed between them. The printing plate blank 30 is then shaped onto the support 29. The doctor blade 17 is curved, and the doctor blade is dam 18 at that part.
It will be seen that together with a and 18b they form and shape the two upper edges 31 and 32 of the printing plate blank.

In a preferred form, the radius of curvature of the semi-cylindrical grooves of manifold 14 is preferably between 60 and 1000 mils, more preferably between 62 and 250 mils. capillary tube 19
is preferably 30 to 500 mils (approximately 0.76 to 12.7 mm), more preferably 90 to 250 mils (approximately 2.29 to 6.35 mm)
with a diameter between. The dam 16 is preferably 0 to 100 mm from the surface of the adjacent support or platen.
mils (0 to about 2.54 mm), more preferably 1 to 20
Located mils (approximately 0.025-0.508mm) apart. The doctor blade 17 preferably has a diameter of 250 to 2000 mils (approximately 6.35 to 50.8 mm), more preferably 500 to 1500 mils.
mils (approximately 12.7 to 38.1 mm) and above the spacer support or platen, preferably 2 to 350 mils (approximately 0.051 to 8.89 mm);
More preferably 2 to 120 mils (approximately 0.051 to 3.048
mm) distance apart.

Manifold 14 is preferably gravity fed with liquid from distribution reservoir 21. The reference liquid level of the polymer in the distribution reservoir 21 is preferably between 1 and 10 the height or water head of the polymer in the distribution reservoir.
inches (approximately 2.54-25.4 cm), more preferably 3
Maintain at ~6 inches. The distribution reservoir 21 is located above the manifold 14, preferably 0.250 to 3.0 inches, more preferably 0.250 to 0.500 inches.
1.27cm). Capillary tubes 19 are where they enter manifold 14 and are preferably spaced on centers at a distance of 125 to 1000 mils, more preferably 250 to 500 mils. .

Carriage 12 is substantially as shown for the carriage of U.S. Pat. No. 3,597,080.
Preferably, it is mounted above the platen and guided over the platen and powered by mounting along guide bars 33 and 34 on both sides. The content of said patent is incorporated herein by reference. The speed of carriage movement is 0.5 to 12.0 inches/second, preferably 1.0 to 3.0 inches/second.

Turning now to the method of the present invention, there is provided a method for forming printing plates by continuously dispensing and shaping a feed of liquid photopolymer. The liquid photopolymer is dispensed and confined in a reservoir within the manifold 14. Manifold 14
moves away from the pool, leaving part of its contents behind. The reservoir remains full and continuous with the contents left behind. The portion of the contents of the puddle that remains behind is flattened and mechanically shaped into a rounded shape along its two edges.

In a preferred method, the reservoir of liquid photopolymer is maintained full by gravity feeding through a capillary tube, and the manifold is spaced apart from the surface onto which the liquid photopolymer is being dispensed in a prespecified amount. and maintain the viscosity of the liquid photopolymer preferably between 500 and 20,000 cps, more preferably between 1.800 and 6,000 cps. The cps values reported herein were determined on a Bruckfield viscometer using a No. 4 spindle at 60 rpm and operating temperature.

Preferably, at shutdown, the liquid photopolymer in the capillary remains in the capillary due to surface tension and no puddle is maintained, but left behind, flattened and shaped. As used herein, the term "capillary" refers only to the property that substantially all of the liquid in the tube remains in the tube when the top of the tube is sealed.

In a practice of forming printing plates using the apparatus and method of the present invention, carriage 12 moves elongated member 13 15 mils (approximately 0.381 mm) above platen 11.
mm). The actual length of the elongate member was 38 inches. Because it includes two parallel liquid dispensing stations and an excipient station, each station
This was because it was a dual unit with a doctor blade length of 15.5 inches. However, for the sake of simplicity, the description will proceed using drawings showing a single station unit.

The rod heaters 27b and 27c are connected to a single 100
A Watts 0.25 inch cartridge heater is substituted and the heater is submerged into the surface of member 13 just above doctor blade section 17. The heater on the distribution reservoir 21 was a 500 watt rod resistor. The width of the doctor blade from the edge of manifold 14 to its outer edge is 1 inch, the radius of curvature of the manifold semi-cylindrical groove is 125 mils, and dam 16 The distance from the outer edge of member 13 was also 1 inch (approximately 2.54 cm). entrance
15 had a hole diameter of 91 mils and the inlet center spacing was 500 mils.

The carriage was positioned to begin its movement across the support sheet. Preheated polymer is fed into the dispensing reservoir through flexible hose 26 to achieve a 4 inch head, with a capacitive proximity switch in place of float 25 providing the cutoff signal. Ivy. The valve means of the single bar member 22 was closed during the initial filling of the delivery reservoir 21. A 10 mil thick aluminum support sheet was placed on the platen. Member 13 was thus spaced 50 mils from the support sheet. The valve means was then opened and the feed outlet 20 was opened by opening the sealing pad means 23. The polymer entered the inlet through capillary tube 19 and flowed to manifold 14. When the polymer appears on the outer edge of doctor blade 17, the carriage begins to move and the polymer puddle in manifold 14 is forced by doctor blade 17 onto support 29, rounded edges 31 and 32. It was spread out in the form of a flat and uniform liquid printing plate blank. The viscosity of the polymer is approximately
It was 2000cps. Adjust the temperature of the distribution reservoir to member 13.
The temperature was maintained at approximately 115°C (approximately 46.1℃).
The polymer was fed into a dispensing reservoir 21 which was preheated to a temperature of approximately 115°C (approximately 46.1°C).

The carriage was moved at a speed of approximately 1 inch/second. The laid down blank is approximately 15.5 inches wide x 24 inches long.
60.96cm). Approximately one second before the carriage reached the end of its laydown movement, an automatic signal closed the feed outlet 20 from the distribution reservoir 21. The polymer in the reservoir is knifed, flattened and shaped, and the polymer in the capillary tube 19 and inlet 15 remains in place. The carriage then returned to its starting position and the liquid level sensing control means 25 issued a signal for the addition of the necessary polymer to refill the head manifold. This replenishment would require approximately 150 ml of polymer for each station.
The amount of polymer in distribution reservoir 21 is approximately 1.5 gallons/station. New 1
A sheet of support was placed in position and the operation was repeated again automatically. The apparatus was operated at a rate of 120 blanks/hour and was stopped at the end of the one hour run by stopping the cycle of the apparatus at the start of the laydown of the photopolymer printing plate blank.

Purging the equipment at shutdown was unnecessary. The polymer was left in the distribution reservoir 21 and in the capillary tube 19 and inlet 15. Since the polymer was not exposed to significant amounts of actinic radiation, it remained at a viscosity of about 2000 cps with the heater on.
Operation began the next day without any special start-up procedures or refilling of the ration reservoir.

After each photopolymer printing plate blank has been cast onto the support 29, the support with the photopolymer printing plate blank is moved to the next station where it is transferred to a chemical via the negative supporting the indicia. After exposure to radiation, uncured polymer was removed with an air knife dry etcher and recycled to a feed tank (not shown) and fed via flexible hose 26. The virgin polymer used in this experiment is available from WR Grace & Co.
LETTERFLEX Y ^TM photosensitive polymer with a virgin viscosity of approximately 2500 cps at room temperature.
It had a recirculation viscosity of 7000 cps. The printing plates were found to have excellent uniformity and to produce minimal recycled material due to accurate laydown of the photopolymer printing plate blanks. Also, because the dam can be several mils (multiple times 0.0254 mm) away from the support, there is no rubbing or straining of the support, and when the equipment is running, there is no significant polymer It was found that no extrusion occurred from the side dam regions 18a and 18b.

During operation, after initial speed and position adjustments, the device was found to operate continuously without maintenance or adjustment. Each successive printing plate was found to be identical in size to the preceding printing plate. The shapes of the printing plates were also the same, with parallel sides and square edges. The first two plates made and the last two plates were compared and found to be identical in size and shape. For the first time, it has become possible to restart a plate-making machine after a period of shutdown (overnight) and to produce printing plates of the same size and shape without extensive adjustments. It was also observed that printing plate production speed could be increased by 33% using this equipment. Finally, the cleaning maintenance of this device is significantly reduced compared to conventional methods.

Although the present invention has been described, for purposes of clarity, with respect to a single sheet laydown unit of photopolymer, in a more preferred form the apparatus provides a pair of laydown units in which a carriage supports the two units in side-by-side relationship. It would be a unit. Furthermore, although the apparatus of the present invention has been described in terms of a moving carriage, it will be apparent that in some cases the platen can be moved instead of member 13. Additionally, although the invention has been described with respect to forming printing plates, it has other uses, such as dispensing photopolymers in the formation of photopolymer floor coverings or electronic photoresists, and dispensing other viscous liquids. and even in excipients, the invention may be useful.

It will be apparent to those skilled in the art that changes and modifications may be made to this invention without departing from its true spirit and scope. Accordingly, the appended claims encompass all equivalent modifications falling within the true spirit and scope of the invention.

[Brief explanation of drawings]

FIG. 1 is a cut away side diagram of the device of the invention in simplified form. 2 is an isometric view illustrating the shape of the bottom surface of the manifold, doctor blade, and elongate member of FIG. 1; FIG. Figure 3 shows the first
FIG. 4 is a rear plan view of the device shown in the figure, viewed from the direction of movement; In the figure, 10... dispensing and shaping device, 11...
platen, 12...carriage, 13...elongated member, 14...manifold, 15...inlet, 1
6...Dam, 17...Doctor Blade, 18
a, 18b...dam, 19...capillary, 20...
Supply outlet, 21... Distribution reservoir, 22... Rod member, 23... Pad means, 24... Sealed operating shaft,
25... Liquid level detection control means, 26... Flexible hose, 27a, 27b, 27c... Rod heater, 29... Support, 30... Printing plate blank,
31, 32... Edge, 33, 34... Guide rod.

Claims (1)

Claims: 1. A method for sequentially dispensing and shaping a liquid to form a series of substantially rectangular sheets, comprising: (a) filling a dispensing reservoir with the liquid to a predetermined depth; (b) intermittently opening and closing a valve means to cause liquid to drain by gravity from the reservoir; (c) draining the liquid from the reservoir through each of the plurality of capillaries; to the inlet of the manifold and maintain the capillary tubes in a substantially liquid-filled state at all times during the successive operations; (e) supplying said liquid through said inlets along a path defined by said inlet and intermittently interrupting the flow of liquid into said manifold from all of said inlets; (e) formed by one edge of an open face of the manifold; (f) supplying liquid to said manifold through a capillary tube, said one of the open faces of said manifold until the contents of said manifold are emptied intermittently; (g) flowing from the outwardly opening portion of the manifold; and limiting the height of the liquid to be less than or equal to the inside height of the manifold; A method characterized in that the liquid is flattened by doctor means, thereby providing a substantially rectangular sheet of liquid. 2. The method of claim 1 for heating the liquid in the distribution reservoir and the manifold. 3 The above liquid flows from the open part of the manifold by moving the manifold in the direction of the dam, and the liquid is flattened by doctoring the surface of the liquid as it flows out from the open part of the manifold. 2. The method according to claim 1, wherein the method is performed by moving the means. 4. The manifold is moved at a speed of 0.5 to 12 inches (about 1.27 to about 30.48 cm) per second,
4. The method of claim 3, wherein the liquid level in the reservoir is maintained between 1 and 10 inches above the manifold. 5. The method of claim 4, wherein the liquid level in the reservoir is maintained between 3 and 6 inches above the manifold. 6 A liquid dispensing and shaping device for dispensing substantially rectangular liquid reservoirs in discontinuous succession, the device comprising: (a) being open on one side and having a plurality of aligned inlets on the opposite side; an elongated linearly aligned manifold having an open surface, one linear edge and at least a portion of the two ends forming a dam, and an opposite side of the linear edge; (b) a doctor blade cooperating with said opposite edge opening outwardly of the manifold; (c) a doctor blade of the manifold; supplying liquid to each inlet and remaining open to the inlet;
a plurality of capillaries which remain filled with liquid during successive operations of the liquid dispensing and shaping device; (d) a plurality of supply outlets supplying liquid to each of the capillaries; (e) a plurality of supply outlets; (f) a gravity feed liquid distribution reservoir for supplying liquid to said plurality of feed outlets; (g) ) reservoir liquid level detection and control means for maintaining the liquid level in the reservoir at a predetermined liquid head; only the liquid head provides liquid pressure to the manifold at the inlet; Device. 7. The doctor blade and the manifold are machined from the same piece of indivisible metal, the doctor blade being adjacent to and extending along the length of the manifold, and the valve means being a single rod. 7. Apparatus as claimed in claim 6, including pad means being a member and engageable with each of said supply outlets. 8 The liquid distribution reservoir is heatable, the manifold is heatable, and the manifold opening portion of the open face of the manifold is provided with a semi-cylindrical groove aligned with the manifold, the curvature of the groove being The radius is between 60 mils and 1000 mils, and the capillary diameter is between 30 mils and 250 mils, and the diameter of the doctor blade is between 30 mils and 250 mils. 8. The device of claim 7, wherein the width is between 250 mils and 2000 mils. 9. Place the manifold, doctor blade, capillary tube, supply outlet, valve means and distribution reservoir and move it along the guide rod above the platen at a speed of 0.5 to 12 inches per second. 9. The apparatus of claim 8, further comprising a carriage which is guided on both sides. 10 The radius of curvature of the groove is 62 mils (approximately 1.58 mm) to 250 mils (approximately 6.35 mm), and the diameter of the capillary tube is 91 mils (approximately 2.31 mm) to 250 mils (approximately 6.35 mm).
and the dam formed by one edge of the groove is between 1 mil and 20 mils from the platen or substrate.
The width of the doctor blade of the above doctor blade is 500 mm.
10. The apparatus of claim 9, which is between 12.7 and 1500 mils. 11 The reservoir liquid level detection control means controls the liquid level height in the reservoir from 1 to 10 inches (approximately 2.54 inches).
0.25 to 0.5 inches above the manifold, with the supply outlet maintained between 0.25 and 0.5 inches above the manifold.
cm to about 1.27 cm), and the inlet of the manifold is centered between 125 mil and 1000 mil (about 0.32 cm).
cm to about 2.54 cm) apart from the first claim
The device described in item 0.