Patent Description:
The present patent application is a divisional application of <CIT>, the claims of which are directed to a method of writing a pre-polymeric formulation on a substrate, to produce a polymeric rule die, the method comprising:.

wherein said pre-polymeric formulation in said canister is degassed to a gas concentration sufficiently low to ensure that over a total length of a contact surface of said cured elongate rule, said contact surface has at most <NUM> surface pocks/meter, said surface pocks having a diameter above <NUM>.

<CIT> discloses a flexible material that comprises one or more types of polymers and may be used for drawing surface-adhesive rules having a pre-defined cross-section profile. Wherein the flexible material has attribute to reserve a shape of a profile of an orifice through which it is deposited from.

According to the present invention, there is provided a polymeric rule die as hereinafter set forth in Claim <NUM> of the appended claims.

The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Throughout the drawings, like-referenced characters are used to designate like elements.

The principles and operation of the polymeric rule die technology according to the present invention may be better understood with reference to the drawings and the accompanying description.

Referring now to the drawings, <FIG> provides a schematic, cross-sectional view of a rule die <NUM> having at least one elongate rule <NUM> having an elongate surface <NUM> adhesively attached to a broad surface <NUM> of a die base <NUM>. Elongate rule <NUM> has an elongate protrusion <NUM> distally protruding from die base <NUM>, elongate protrusion <NUM> having an elongate die surface <NUM>. Typically, elongate rule <NUM>, and more particularly, elongate die surface <NUM>, predominantly include at least one polymeric material.

Elongate protrusion <NUM> may be directly adherent to die base <NUM>. In some embodiments, however, elongate surface <NUM> is appreciably broader than elongate die surface <NUM>, and forms a portion of elongate rule base <NUM>. Elongate rule <NUM> may have a tapered segment <NUM> connecting between elongate protrusion <NUM> and elongate rule base <NUM>. In some embodiments, tapered segment <NUM> may be extremely small or non-existent, as elongate protrusion <NUM> and elongate rule base <NUM> meet at an angle α of <NUM>°, ±<NUM>°, ±<NUM>°, ±<NUM>°, ±<NUM>°, or ± <NUM>°. Typically the angle is at least <NUM>°.

From the transverse cross-sectional view of rule die <NUM> provided in <FIG>, it will be appreciated that the length (Lr) of die surface <NUM> of elongate rule <NUM> is appreciably greater than the height of the rule, Hr.

With reference now to <FIG> as well, the width (Wr) of the rule, proximate to the contact or die surface <NUM> (towards the rule "tip"), may be a fraction of Hr. In some embodiments, a ratio of Wr to Hr may be within a range of <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>.

In some embodiments, length Lr of die surface <NUM> may be at least <NUM>, at least <NUM>, or at least <NUM>.

In some embodiments, width (Wr) may be at most <NUM>, and more typically, within a range of <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>.

In some embodiments, elongate surface <NUM> may have a base width Wb exceeding Wr by at least <NUM>, and more typically, by at least <NUM>, by at least <NUM>, or by at least <NUM>, and typically, by at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM>.

In some embodiments, the ratio of Wb to Wr may be at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM>.

In some embodiments, Hr may be within a range of <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>.

In some embodiments, Hp, the height of elongate protrusion <NUM>, may be within a range of <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>.

The inventors believe that contact surface widths (Wr) below <NUM> are unknown. Similarly, low ratios of Wr to Hr may also be unknown. As used herein in the specification and in the claims section that follows, the term "contact surface width", "rule width proximate to the contact or die surface <NUM>", "Wr" and the like, refer to the broadest width of the rule within <NUM> of the tip of the rule.

Without wishing to be bound by theory, the inventors believe that the need for the rule to withstand high pressure delivered to the contact surface, along with, in many cases, rotational forces delivered to the long side of the rule, in combination with many other constraints (many of which will be discussed below), have heretofore precluded the advent of such-dimensioned rules.

<FIG> provides a schematic, partially cross-sectional view of an exemplary surface mounted rule die system <NUM> including a rule die <NUM> that may be functionally similar or identical to rule die <NUM> of <FIG>. Disposed generally opposite rule die <NUM>, and generally opposite an elongate die surface <NUM>, is a counter-die <NUM>, which may have a broad counter-die surface <NUM> facing elongate die surface <NUM>.

Counter-die <NUM> may be multi-layered. In the exemplary embodiment provided in <FIG>, counter-die <NUM> includes a counter-die base <NUM> such as a rotating drum, and a counter-die contact pad, sheet, or layer <NUM> attached or secured to base <NUM>, and having, distal to base <NUM>, broad counter-die surface <NUM> a sheet or backing sheet <NUM>. In some embodiments, counter-die contact pad <NUM> may be directly attached or secured to base <NUM>. However, as shown, counter-die contact pad <NUM> is attached to a counter-die sheet <NUM> disposed in intermediate fashion with respect to pad <NUM> and counter-die base <NUM>.

A workpiece sheet such a cardboard sheet <NUM> is shown intermediately disposed between die surface <NUM> and broad counter-die surface <NUM>.

Rule die system <NUM> is adapted such that a pressure exerted by the die surface <NUM> against a top or proximate surface <NUM> (i.e., facing die surface <NUM>) of cardboard sheet <NUM> forms an elongate depression in surface <NUM>. The pressure may be exerted by a variety of systems such as mechanized pressing or pressuring system <NUM>, as will be appreciated by those of skill in the art, and is shown schematically.

<FIG> provides a partial side view of such a rule die system, in the act of creasing a cardboard sheet. The rule die is disposed opposite a resilient counter die, with the die surface protruding into the sheet or substrate disposed therebetween, and depressing the counter die surface, to form a crease in the sheet.

<FIG> provides a schematic diagram with relevant elements of a portion of a rule-writing system such as a rotary system <NUM>. Rotary system <NUM> may be used for drawing a plurality of rules <NUM>-<NUM> on a surface of a die base or substrate <NUM>. Rules <NUM>-<NUM> may protrude from the surface of base <NUM> and may have different shapes and sizes. Rules <NUM>-<NUM> may be configured to crease a surface of a cardboard sheet.

Rotary system <NUM> may include a drum <NUM> on which base <NUM> may be positioned. Base <NUM> may be associated with or joined to the drum <NUM> by means of adhesion or gripping.

In some embodiments, base <NUM> may be removed from drum <NUM> after rules <NUM>-<NUM> are produced. In other exemplary embodiments, base <NUM> of the die may be left on the drum <NUM>, to be used for creasing cardboard sheets in a rotary creasing system. In some embodiments, rotary system <NUM> includes at least one additional drum (not shown) that is adapted and positioned to serve as a counter-die.

In some embodiments, the counter-die contact surface or layer and/or base <NUM> may be made of a flexible film. The flexible film may include at least one type of polymer such as a polyethylene terephthalate (PET). Exemplary polymers include polyester, polyamide, and polycarbonate. Metallic films or foils such as aluminum foil or copper foil may also be suitable.

The flexible film of the counter-die may have a strong enough sustainability, firmness, inside-cohesion, robustness, to withstand the pressure and harsh operation which can be around a few tons of press force in one or more directions during the creasing of the cardboard workpieces.

Rotary system <NUM> may further include one or more rule-drawers. The rule-drawer may include a drawing head <NUM>, a controller <NUM>, and one or more rails <NUM>. Drawing head <NUM> may include a nozzle arrangement <NUM>, and at least one canister <NUM> fluidly associated with arrangement <NUM>. Arrangement <NUM> may be associated with rail <NUM>. In some embodiments, arrangement <NUM> may slide along rail <NUM>. In some embodiments, canister <NUM> may also be associated with rail <NUM>. In some embodiments, canister <NUM> may be independent of rail <NUM>. Canister <NUM> may contain a rule-forming formulation for discharging under pressure by arrangement <NUM>, so as to draw rules <NUM>-<NUM>. In some embodiments, such pressure may be induced or delivered by a pneumatic system, or by a positive displacement system.

In some embodiments, the canister <NUM> and arrangement <NUM> may be associated with, or controlled by, a motor for moving canister <NUM> and/or arrangement <NUM> back and forth on rail <NUM> in a direction indicated by arrow <NUM>. In addition, arrangement <NUM> may be adapted to rotate in the directions indicated by arrows <NUM>. Arrangement <NUM> may also move up and down in the directions indicated by arrows <NUM>. In some embodiments, drawing-head <NUM> may form a single unit, while in other embodiments, nozzle arrangement <NUM> and canister <NUM> may be moved independently from one other.

Drum <NUM> may be adapted to rotate in a counter-clockwise direction, as indicated by arrow <NUM>. Optionally, drum <NUM> may rotate in a direction opposite to the direction indicated by arrow <NUM> (i.e., clockwise), or may rotate in both directions. Drum <NUM> may also be configured to move laterally in relationship to the rail. Controller <NUM> may control and coordinate the movement and operations of the different modules or elements, as well as the operations of rotary system <NUM>. Controller <NUM> may control the rotation of drum <NUM>, and the movement of nozzle <NUM> and canister <NUM>. Controller <NUM> may also instruct and control arrangement <NUM> and canister <NUM> so as to deposit resin on die base <NUM> to produce a desired or pre-defined layout or pattern of rules <NUM>-<NUM>.

The resin output by arrangement <NUM> may be hardened after and/or while the drawing is being performed. The hardening may be accomplished by a curing or hardening apparatus, such as a curing lamp <NUM>.

Curing lamp <NUM> may radiate energy that can cause the drawn resin to harden and/or adhere. The radiated energy may include ultraviolet (UV) light, visible light, heat, etc..

The type of energy irradiated by curing lamp <NUM> generally depends on the type of resin and the hardening characteristics of that material. For example, when the resin is a thermosetting material, heat may be applied by curing lamp <NUM>. When the resin is a thermoplastic material, curing lamp <NUM> may cool the material in order to harden it. When the resin includes a photo-initiator, curing lamp <NUM> may provide UV lighting to cure the resin.

Curing lamp <NUM> may be positioned adjacent to the nozzle <NUM> such that the resin may be hardened immediately after it is drawn. In other exemplary embodiments curing lamp <NUM> may be positioned at a distance from the nozzle <NUM>.

<FIG> illustrates an exemplary portion with relevant elements of a flat system such as a Cartesian coordinate system <NUM>. System <NUM> may be used for drawing a rule <NUM> on the surface of a die base <NUM> that may be positioned on a flat substrate <NUM>. System <NUM> may include at least one rule-drawer. In some embodiments, the rule-drawer may include a drawing-head <NUM>, a controller <NUM>, and one or more rails <NUM>. Drawing-head <NUM> may include a nozzle arrangement <NUM> and at least one canister <NUM> associated with, or fluidly coupled to, arrangement <NUM>.

Rule <NUM> may be drawn by nozzle <NUM>. Arrangement <NUM> may be associated with a motor powering arrangement <NUM> to traverse along rail <NUM> in the directions of arrow <NUM>, for example. Arrangement <NUM> may be adapted to rotate in directions illustrated by arrows <NUM> and/or <NUM>. Rail <NUM> may be situated between two rails <NUM>, substantially perpendicular to rail <NUM> and may be adapted to travel in the directions of arrow <NUM>, for example.

Controller <NUM> may be adapted to control the movement of the different modules of system <NUM>. For example, controller <NUM> may control arrangement <NUM>, rail <NUM>, and canister <NUM>. In some embodiments, system <NUM> may further include a lamp such as a UV lamp <NUM>, adapted to cure rule <NUM> such that rule <NUM> firmly adheres to the surface of base <NUM>.

<FIG> provides an exemplary embodiment of a drawing-head <NUM>. Drawing-head <NUM> may include a nozzle arrangement <NUM> for depositing a continuous length ("bead") of resin. Arrangement <NUM> may be associated with or fluidly coupled to a canister <NUM>.

<FIG> provides a perspective illustration of an exemplary nozzle arrangement 700a. Arrangement 700a may include a first tube <NUM> that may be substantially perpendicular to a base <NUM> of the rule die. A second tube <NUM> may be oriented substantially perpendicular to first tube <NUM> and parallel to base <NUM>. Tube <NUM> may have an orifice <NUM> at its end, through which resin may be output towards base <NUM>.

<FIG> provides a perspective view of another nozzle arrangement 700b. Arrangement 700b may include a tube <NUM> oriented substantially perpendicular to a die base <NUM>. Tube <NUM> may include an orifice <NUM>, through which resin may be output toward base <NUM>. Optionally, tube <NUM> may be closed at a distal end <NUM>, and the material may be released substantially parallel to die base <NUM>, through opening <NUM>. Alternatively, distal end <NUM> may be open and the resin may be output in a substantially perpendicular manner through distal end <NUM>, as well as through orifice <NUM>.

A schematic perspective view of a canister having a generally trapezoidal orifice geometry is provided in <FIG>.

<FIG> schematically illustrates a pressure actuator 800a. Pressure actuator 800a may be an air-pump actuator having a canister <NUM> adapted to contain a resin <NUM>. Canister <NUM> may have an output <NUM> that fluidly couples canister <NUM> to a nozzle. The canister may have an input <NUM> through which air may be compressed and thus pneumatically drive out resin <NUM>, through output <NUM>, via a nozzle (not shown) so as to draw rules. The air may be compressed by a piston <NUM>, which may be controlled by a controller.

<FIG> schematically illustrate a flowchart showing relevant processes or actions of an exemplary rule drawing or writing method <NUM>. The illustrated rule drawing method <NUM> may be executed by a processing device such as controllers <NUM> (<FIG>) or <NUM> (<FIG>). Method <NUM> may be initiated <NUM> upon powering on the controller or by other processes, system, events, user actions, etc. During initiation <NUM>, the controller may operate to detect the various modules in the system or, the various modules or other processors may provide information to the controller to identify the different modules. Exemplary modules may include, but are not limited to: drawing head modules, different registers, different timers, etc. After being invoked, the process may then act to reset, initialize or determine the state of various resources, registers, variables, memory components, etc. <NUM>. The various resources may include timers (t), counters (R), and distance measuring units (D).

After the system resources have been initialized <NUM>, rule drawing method <NUM> may enter a delay loop waiting for the reception of an initiation command <NUM>. The initiation command directs the rule drawing method <NUM> to commence the creation of a rule die. When an initiation request is received <NUM>, method <NUM> may proceed to act <NUM> by receiving or obtaining the entry of various inputs or parameters used in the creation of a rule die. The inputs may be received, obtained or entered by a user, provided by a processor or other entity, or read from an electronic file. Exemplary inputs may include, but are not limited to: the depth or thickness of the cardboard that will be pre-treated while using the rule die, the type of rules that will be required, the requested layout, and so on. Method <NUM> may check <NUM> a look-up table for information on the required job description. Exemplary information may include the definition of flow index for each rule, the definition of profile for each rule, the definition of the layers for the co-layers, the type of rule creasing, etc..

Once the information has been received, the method then decides whether additional information in the look-up table has been found or is available <NUM>. If additional information is not found <NUM>, then method <NUM> may prompt the user or other information provider to enter or provide the information <NUM>, and processing then returns to act <NUM> to check for this information. If the method obtains the information in the look-up table or otherwise <NUM>, then method <NUM> may proceed to act <NUM>. Method <NUM> may then proceed to execute a rule drawing loop that includes the acts listed in blocks <NUM> through <NUM> (<FIG>). The first action in the rule drawing loop includes increasing counter R by one (incrementing R) <NUM>, and method <NUM> may begin drawing a rule in accordance with the information received at action <NUM> and layout requirements.

Once the counter is increased, the method continues by adjusting or setting <NUM> the height and angle of a nozzle t. In addition, the velocity of the drawing head modules may be accelerated <NUM> to a required velocity V1 by acceleration rate a1, for example. The pressure applied by a one or more pressure actuators may also be raised <NUM> to a required pressure P1. In some embodiments, e.g., in which screw-pumps are used, a screwing speed may be raised instead of raising pressure P1. Next, method <NUM> may proceed to act <NUM> at <FIG>.

After adjusting or setting the nozzle, velocity and pressure, the method continues by entering a delay loop <NUM> until the value of timer t is equal to t1. The value of t1 may be calculated according to the mechanical capabilities of the drawing-head and the length required for the rule or rule segment according to the layout. When timer t value is equal to the value of t1, the acceleration rate a1 of the velocity of the drawing head modules may be stopped <NUM> and the raising of the pressure of the pressure actuator may be stopped <NUM> as well. Thus the drawing head modules may continue drawing at velocity V1 and the pressure actuator may continue pressing at pressure P1. In alternate embodiment instead using a timer, a distance measurement D may be used. Distance measurement D may be expressed by a number of steps given to a step-motor or by feedback received from a step measurement encoder associated to the drawing head.

While the drawing continues, the method <NUM> may enter into a delay loop until the value of counter t is equal to t2 <NUM>. Wherein t2 may be calculated from inputs on the drawn pattern of the rule and the velocity that was reached at t1. When the timer t value is equal to t2 <NUM>, the velocity of the drawing head modules may be decelerated <NUM> to V2 at deceleration rate a2, and the pressure by the pressure actuator may be decreased <NUM> to P2. In exemplary embodiments, the nozzle may be <NUM> elevated X mm and turned <NUM> to an angle O according to the requirements of the layout. Next the nozzle may be lowered <NUM> Z mm (wherein Z may equal X).

Method <NUM> continues by accelerating the drawing head modules to a velocity of V1 at an acceleration rate of a1, and the pressure of the pressure actuator may be raised to P1 <NUM>. The drawing head modules may continue to draw <NUM> the rules according to the layout. Method <NUM> may then proceed to act <NUM> at <FIG>.

Method <NUM> continues at act <NUM> of <FIG> by entering a delay loop until the value of the timer t is equal to t3 <NUM>. When the timer t value is equal to t3 <NUM>, the acceleration of the velocity of the drawing head modules and the raising of the pressure by the pressure actuator may be stopped <NUM>. The drawing head modules may continue drawing at velocity V1 and the pressure actuator may continue at pressure P1 <NUM>. Next, method <NUM> may enter a delay loop until the value of timer t is equal to t4 <NUM>. When the timer t value is equal to t4 <NUM>, the pressure imposed by the pressure actuator may be stopped <NUM>, and the motion of the drawing head modules may be stopped <NUM> as well. The nozzle may be elevated to a desired level by raising it Y mm and then controlled to spin sharply <NUM> at a particular angle (e.g., <NUM>-<NUM>°) around its center, for example. The spinning of the nozzle serves to cut the flexible material from the nozzle. One of skill in the art will appreciate that an air-pulse, shutter, blade, or air knife may similarly be used to cut the flexible material from the nozzle. Method <NUM> may then proceed to step <NUM> in <FIG>.

At this point in the process, method <NUM> may provide an indication <NUM> that the rule has been drawn. Next, method <NUM> determines whether all of the rules have been drawn and the job has been finished <NUM>. If the job is finished <NUM>, then method <NUM> may provide a suitable indication <NUM>. If the job has not yet been finished, then method <NUM> may return to step <NUM> of <FIG> to commence drawing the rule.

With regard now to the formulations used to produce the rules, the rule formulations were prepared according to the following procedure:
Into a <NUM> mixing vessel are added up to about <NUM> grams of weighed formulation components. The mixing vessel is introduced to a planetary centrifugal vacuum mixer, and the following mixing sequence is applied: <NUM> at 1000rpm, applying a deep vacuum in order to degas the formulation; <NUM> at 2000rpm under vacuum (10KPa); gradually raising the pressure, from 10KPa to atmospheric pressure, to prevent air bubbles from entering the formulation: <NUM> at 1000rpm under vacuum (30KPa), <NUM> at 2000rpm under vacuum (60KPa).

To the obtained mixture, any remaining thickening agent is added, and mixing ensues as follows: <NUM> at 2000rpm, applying a deep vacuum in order to degas the formulation; <NUM> at 1000rpm under vacuum (10KPa); <NUM> at 2000rpm under vacuum (10KPa); gradually raising the pressure, from 10KPa to atmospheric pressure, to prevent air bubbles from entering the formulation: <NUM> at 1000rpm under vacuum (30KPa), <NUM> at 2000rpm under vacuum (60KPa).

To further degas the formulation, the obtained resin may be transferred to a <NUM> centrifuge swinging-bucket rotor (H-<NUM>). The resin may undergo centrifuging at <NUM> RPM for about <NUM> using a Sorvall RC 3C centrifuge or an equivalent thereof.

The degassed resin obtained may be introduced to a canister under pressure. It may be advantageous to yet further degas the formulation. The canister may be placed in an oven for <NUM> at <NUM>. Subsequently, pairs of canisters may be loaded into the rotor by utilizing an H-<NUM> adaptor. The resin-filled canisters may then undergo centrifugation at <NUM> RPM for about <NUM>.

Planetary centrifugal vacuum mixer -- THINKY MIXER ARV-310CE.

Reference is now made to the following examples, which together with the description provided herein, illustrate the invention in a non-limiting fashion.

Ten rule formulations (Examples <NUM>-<NUM>) were prepared in accordance with the above-described procedure. The formulation compositions are provided below, in weight-percent:.

Example <NUM> was prepared using the same composition as Example <NUM>, but without performing the de-aeration steps.

Example <NUM> was prepared using the same proportion of components as Example <NUM>, but with <NUM>% (instead of <NUM>%) AEROSIL <NUM>.

In order to evaluate various mechanical properties, the written rules were cured according to the following standard curing procedure:
The ultraviolet (UV) curing system used was LC6B Benchtop Conveyor of Fusion UV Systems, Inc. (Maryland, US). Curing was performed at room temperature, with a UV power of <NUM> watts/cm (<NUM> watts/inch), three passes at a belt speed of <NUM>/min.

Some of the cured formulations being subjected to mechanical testing were processed according to ASTM <NUM>-<NUM>, Type I (table), to obtain the requisite size and shape for the mechanical testing.

In order to evaluate mechanical properties associated with creasing, the written rules were cured according to the following procedure:
The ultraviolet (UV) curing system used had a UV lamp. Curing was performed at room temperature, with a UV power of <NUM> watts/cm. For each sample, the drum was rotated three times, at a drum jogging speed of <NUM>/second. The UV lamp was fixed at a distance of <NUM> from the PET film serving as the rule substrate.

The formulations may be dispensed from the canister, through an orifice, under pressure, e.g., by pneumatic force or by positive displacement. While various orifice geometries may be used, in all experiments described herein, the orifice geometry was substantially as shown in <FIG>.

The inventors have discovered that there are various, somewhat rigorous conditions that the formulations must fulfill in order to succeed in writing a rule having a first set of appropriate characteristics, and, following curing, having a second set of appropriate characteristics.

For some embodiments, the inventors have discovered that the presence of gas (e.g., air, or nitrogen) within the rule formulation, even in small quantities, may be extremely detrimental to rule performance. Gas bubbles in the uncured formulation may affect the rheological properties of the formulation under pressure in the canister, or during writing of the rule. Gas bubbles in the bulk of the cured rule may detract from various requisite mechanical characteristics, and may appreciably reduce the lifetime of the rule (e.g., the number of creases achieved prior to failure or prior to producing off-standard creases). Moreover, any gas bubbles disposed at or near the contact surface of the rule may cause pocking of the contact surface, which may compromise or substantially destroy creasing quality.

<FIG> provides a schematic cross-sectional view of a rule having pockmarks resulting from the liberation of gas bubbles.

As described hereinabove, the inventors have developed a procedure to degas the highly viscous formulations of the present invention, to remove any gas generated or liberated during the preparation procedure, and to remove additional gas that may be introduced to the canister during the filling process.

Moreover, the inventors have developed a procedure to quantitatively distinguish between sufficiently and insufficiently degassed batches, by measuring the specific gravity, or density, of the resin beads, as follows:
Two batches of the formulation of Example <NUM> were prepared, a first batch that underwent the vacuum and degassing procedures described hereinabove, and a second batch prepared in identical fashion, but without vacuum and degassing procedures (Example <NUM>). A cylinder-shaped resin bead or was produced by extruding the resin from a canister having an orifice diameter of <NUM>. The bead length was <NUM> for each batch of the formulation. Both resin beads were disposed on a PET film.

<FIG> is a photograph of the bead corresponding to the undegassed formulation; <FIG> is a photograph of the bead corresponding to the degassed formulation, in accordance with the present invention. As may be evident from <FIG>, the bead corresponding to the undegassed formulation has a pocked surface as well as bubbles within the bead. The bubbles contribute to the light diffraction that may be observed in the bead. By sharp contrast, the bead corresponding to the degassed formulation is substantially devoid of bubbles and surface pocks, contributing to the mechanical strength of the rule die, uniformity of mechanical properties, and the smoothness of the rule die contact surface.

While it is possible to measure the density of a bead in an uncured state, e.g., by submerging the bead in a liquid (of known volume and weight) to obtain differential volume and weight values, the inventors have found it convenient to at least partially harden the bead. The hardening criterion is simply the effecting of sufficient polymerization for the bead material not to stick to the side walls of the glass tube partially filled with water, as the bead is introduced thereto.

To this end, the PET foil with the resin beads was introduced to the UV - LC6B Benchtop Conveyor machine (belt speed: <NUM>/min) for a single cycle. Resins of other compositions might require additional curing, if sticking is observed.

The glass tube was pre-weighed, and was weighed again after partial filling with <NUM> of water. The resin bead was then submerged in the water, and both the volume (using the meniscus) and the new glass tube weight were determined.

Each measurement was performed <NUM> times using the same bead material for repeatability assurance, and <NUM> times with different bead materials to determine variability.

With regard to repeatability, the five beads produced from the degassed formulation had a density that varied by about ±<NUM>/cm<NUM>; the five beads produced from the undegassed formulation had a density that varied by about ±<NUM>/cm<NUM>. With regard to variability, the five beads produced from the degassed formulation had an average density of about <NUM>/cm<NUM> ±<NUM>; the five beads produced from the undegassed formulation had an average density of less than <NUM>/cm<NUM>.

As used herein in the specification and in the claims section that follows, the term "baseline density", or "ρbaseline", refers to the density achieved by a resin formulation that was prepared according to the procedure described hereinabove, and used to prepare Examples <NUM> to <NUM>.

As used herein in the specification and in the claims section that follows, the term "bulk density", or "ρbulk", refers to the density achieved by a resin formulation that was prepared according to the procedure described hereinabove, but without any of the degassing procedures, as used to prepare Example <NUM>.

Since, as delineated above, ρbaseline and ρbulk may be determined in an uncured state, or in an at least partially cured state, the terms "baseline density" and "bulk density" may refer to any of these states. Of course, the differential, defined by Δρ = ρbaseline - ρbulk, must be evaluated on formulations that are both uncured, or have been subjected to the identical curing procedure.

In any event, in some embodiments of the present invention the differential density, Δρ = ρbaseline - ρbulk, is at least <NUM>, or at least <NUM>, and more typically, at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>, and in some cases, at least <NUM>.

Often, gas bubbles within the rules (both cured and uncured) may be visually observed. In the rules of the present invention, over a total length of the rule or rules, the bubble content of visually-observable bubbles, having a diameter (or a small dimension, for elongated bubbles) above <NUM>, is at most <NUM> bubbles/meter, and more typically, at most <NUM> bubbles/meter, at most <NUM> bubble/meter, at most <NUM> bubbles/meter, at most <NUM> bubbles/meter, at most <NUM> bubbles/meter, or at most <NUM> bubbles/meter. By way of example, if there exists a single die having a total length of <NUM> meters of the polymeric rules, and <NUM> visually-observable bubble is observed, the bubble content would be about <NUM> bubbles/meter, which would satisfy the criterion of "at most <NUM> bubbles/meter", but would fail to satisfy the criterion of "at most <NUM> bubble/meter".

In some embodiments, over a total length of the die or contact surface of the formulation, rule or rule die, a presence of visually-observable surface pocks, depressions, or craters, or surface pocks, depressions, or craters having a diameter above <NUM> is at most <NUM> pocks/meter, at most <NUM> pocks/meter, at most <NUM> pocks/meter, at most <NUM> pocks/meter, at most <NUM> pocks/meter, at most <NUM> pock/meter, at most <NUM> pocks/meter, at most <NUM> pocks/meter, at most <NUM> pocks/meter, or at most <NUM> pocks/meter.

Even after thorough degassing of the formulations, the inventors have found that while various formulations may successfully be written onto a die substrate or film, there are numerous reasons that the resultant rule may not perform in satisfactory fashion.

The formulation described in Example <NUM> is a highly viscous polymeric formulation, devoid of any thickening agent (e.g., a three-dimensional network former such as silica). Despite the apparent suitability of the viscosity, the inventors were not successful in writing or drawing a rule, under standard writing conditions.

<FIG> are photographs of written rules having disadvantageous features. While the rule in <FIG> advantageously has a relatively flat upper (die or contact) surface along the predominant longitudinal portion of the rule, the rule end is spiked, which may deleteriously affect crease quality. The rule provided in <FIG> also has a relatively flat upper surface along the predominant longitudinal portion of the rule. However, towards the end of the rule has a bulge extending upwards and to the sides, which, again, may deleteriously affect crease quality.

The formulation described in Example <NUM> produced a continuous rule, however, both the shape replication (with respect to the rectangular orifice geometry) and the shape retention (after writing, until curing ensues) appeared unsatisfactory. <FIG> provides a photograph of a rule written using the formulation of Example <NUM>.

The formulation described in Example <NUM> produced a continuous rule. However, from the cross-sectional profile of Example <NUM> provided in <FIG>, it is manifest that the shape of the cured rule has little resemblance to the rectangular geometry of the writing orifice.

In terms of rule writing, the formulations described in Examples <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and <NUM> produced continuous rules on the PET substrate, generally of good form.

The formulation described in Example <NUM>, which had a high glass transition temperature, achieved excellent hardness upon curing. During the curing process, however, the rule underwent appreciable shrinking, and became detached from the PET substrate.

The inventors have found that various rheological characteristics of the formulations may be useful in formulating formulations suitable for writing rules. These characteristics may also provide significant guidance in selecting materials for those formulations.

One important rheological parameter is the storage modulus, G', which characterizes the deformation energy stored by the sample during the shear process. After the load is removed, this energy is completely available, and may act as the driving force for the reformation process, which partially or completely compensates the previously obtained deformation of the structure. Materials that store the entire deformation energy are considered reversibly deformable, or elastic.

The loss modulus, G", characterizes the deformation energy consumed by the sample during the shear process. In other words, G" represents the viscous behavior of a material.

The rheological test procedure was performed as follows:
The material sample was checked for air bubbles in order to assure the reliability of the test. An AR2000 Rheometer, having a <NUM> stainless steel cone (<NUM> degrees) was used. Following calibration, the cone-plate distance reached a gap of <NUM>, a standard instrument parameter. Excess resin was removed from the sample plate and which was then covered with the apparatus cover to maintain temperature at <NUM>.

Time sweep tests were performed under these conditions:.

Plots of G' as a function of time were then generated.

<FIG> provide comparative plots of G' as a function of time (and Step No.) for the formulations of Examples <NUM>-<NUM> and <NUM>.

The inventors have observed that formulations having a relatively low G' in STEP <NUM> may be generally unsuitable for the writing procedure. Empirically, the formulations of Example <NUM> and Example <NUM> were found to write less well than the other exemplary formulations. Plots for Example <NUM> and Example <NUM>, provided in <FIG>, show that G' in STEP <NUM> is below about <NUM> Pa for Example <NUM> and below about <NUM> Pa for Example <NUM>.

Moreover, many of the formulations exhibited thixotropic behavior, which manifested itself in the recovery time in STEP <NUM> to regain the initial value of G' in STEP <NUM>, following the intense oscillation stress of 300Pa in STEP <NUM>. Many of the formulations (e.g., Example <NUM>, Example <NUM>) failed to regain the initial value of G', within the timeframe of STEP <NUM>.

The inventors believe that the lag time in regaining a minimal G' threshold may be important in screening out formulations that are generally unsuitable for the present invention. That minimal threshold, under the above-delineated conditions for the time sweep tests, may be at least <NUM>,<NUM> Pa, within <NUM> seconds of the abrupt relaxation of stress at the end of STEP <NUM>. Without wishing to be bound by theory, the inventors believe that below such a minimal G' recovery threshold, the resultant rule profile may be rounded (poor shape replication and/or shape retention), and the shape may actually worsen with time before the onset of curing. Above this threshold, the thixotropic lag may not be detrimental. The rules produced from Examples <NUM>, <NUM>, <NUM>, and <NUM> all exhibited reasonable rule profiles, despite the clear thixotropic behavior in STEP <NUM>. Similarly, Example <NUM> produced an acceptable rule profiles, despite the clear thixotropic behavior in STEP <NUM>. In these <NUM> formulations, the minimum G' value recorded after <NUM> seconds into STEP <NUM> was over <NUM>,<NUM> Pa.

Other features of the formulations and rule dies of the present invention may be shown using various characterizations. One such characterization is a "standard deformation procedure".

Writing of the rules was effected via a nozzle or orifice of a canister filled with each formulation. Pressure was applied by means of positive displacement (a pneumatic mechanism may also be used), the absolute pressure being a function of, inter alia, the rheological properties of the formulation. The nozzle had a rectangular profile: of <NUM> width and <NUM> height. The distance of the nozzle from the substrate film (PET) was approximately <NUM> micrometers.

Curing was effected according to the procedure provided in Example <NUM>.

Each cured rule was then cut to a rectangular profile of <NUM>•<NUM> (Hp•Wr), to form a rectangular prism.

The <NUM> gsm cardboard sheets were of the American Bristol category, having dimensions of <NUM>•<NUM>. The running or feeding speed was <NUM> pph (papers per hour). It will be appreciated by those of skill in the art that various rotary machines of this type are commercially available.

The lower drum had a polyurethane counter-die having a thickness of <NUM>. The crease pressure depth was <NUM>.

For each rule being tested, three lines of <NUM> in length were written in the cross machine direction. After completing the run of <NUM> sheets, three lines of <NUM> in length were again written in the cross machine direction using the same PET sheet (for reference). The partially creased cardboard substrate was then removed. Thirty cardboard sheets are processed in this manner for each tested rule. Subsequent to this procedure, a picture of a representative rule cross-section is taken using OGP, "Starlite" tool, model: QVL Starlite <NUM>.

As used herein in the specification and in the claims section that follows, this procedure is termed "standard deformation procedure".

Some deformation in the rule may be observed following this accelerated test. Typically, lateral deformation is an important component of the deformation. <FIG> provides images of rules produced from the formulations of Examples <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, before and after the deformation procedure was conducted. The procedure was not the full "standard deformation procedure", in that the rules were not trimmed to the standard rectangular profile of <NUM>•<NUM>.

It is observed that the rule produced from formulation <NUM> exhibited poor overall shape replication/retention, and the rule height was well short of the required <NUM>. It must be emphasized that the heights measured in <FIG> refer to Hr and not to Hp.

It is further observed that the rules produced from formulations <NUM> and <NUM> exhibited appreciable lateral deformation. In contrast, rules produced from formulations <NUM>, <NUM> and <NUM> exhibited negligible, or substantially no, lateral deformation.

This deformation may be quantified in many ways, as will be appreciated by those of skill in the art. One practical quantification method is provided below:
Following the standard deformation procedure, the photograph of the representative rule cross-section is imported to "Photoshop". The rule cross-section is divided into left and right sections. Because deformation largely occurs from the top side of the rule, the division is made using a vertical line (having a substantially infinitely small width), drawn up from the middle of the bottom side of the cross-section (i.e., connected to the elongate rule base).

<FIG> provides a schematic view of a rule cross-section after being cut to a rectangular profile, according to the standard deformation procedure; <FIG> provides a schematic view of this rule cross-section, after concluding the writing portion of the procedure.

The data from Photoshop may be imported into Excel or the like. In the quantification procedure, the number of dark pixels on each side of the vertical division line is counted. In gray scale, "<NUM>" is black, and "<NUM>" is white. All pixels exceeding a value of <NUM> were considered to be white. This procedure is repeated for each rule.

With reference again to <FIG>, the rule on the left side (to the left of the division line) fills only about <NUM>% of the original area filled by the rule (as shown in <FIG>); the rule on the right side fills about <NUM>% of the original area filled by the rule. Dividing the larger value (VL) by the smaller value (VS), we obtain the coefficient of deformation, CD: <MAT>.

In the present invention, the coefficient of deformation (CD) may be at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM>.

Another way of characterizing the rule quality is to evaluate the creasing quality of the rule subsequent to the standard deformation procedure. The creasing quality may be evaluated using commercially available folding-force measuring equipment. In the procedure and evaluations provided hereinbelow, creasing quality was evaluated using a Thwing Albert device (Model: <NUM>-<NUM> PCA Score Bend/Opening Force Tester), at a bending speed of <NUM>/min. The device measures the folding force for every <NUM> degree of folding, until a folding angle of <NUM> degrees has been achieved. In this standard test, the maximum force applied is the measured folding force. The experiment is repeated on two standard creases produced by each rule being tested (and more preferably, on <NUM> creases), for statistical purposes. The values obtained are normalized by dividing by the mean folding force required for uncreased sheets of the identical cardboard, and converting to percentage form, to obtain the mean folding force ratio.

As used herein in the specification and in the claims section that follows, the term "standard crease" refers to the crease made by a rule after the rule has completed the standard deformation procedure, according to the creasing parameters delineated within that procedure.

The results for rules produced from the formulations of Examples <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> (as shown in <FIG>) are provided in the table below, and are provided graphically in <FIG>.

Rules of the present invention may have a mean folding force ratio of at most <NUM>%, at most <NUM>%, at most <NUM>%, at most <NUM>%, at most <NUM>%, at most <NUM>%, at most <NUM>%, at most <NUM>%, at most <NUM>%, or at most <NUM>%. Typically, the folding force ratio is at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, or at least <NUM>%.

<FIG> is a stress-strain plot for various formulations (Examples <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>) cured according to the standard curing procedure of Example <NUM> to produce cured (rule) materials having the requisite (ASTM <NUM>-<NUM>) shape and dimensions. These materials were subjected to stress-strain testing, using an Instron <NUM> tensile machine. The crosshead speed was <NUM>/min, the second crosshead speed was <NUM>/min, and the full-scale load range was 5kN.

Numerical values for various stress-strain parameters: stress at yield, strain at yield, stress at maximum load, strain at break, Young's modulus, and energy to break point are provided in the table below:.

From the data: the formulations according to the present invention, when cured according to the standard curing procedure, and prepared in accordance with the procedure provided in Example <NUM>, and tested in accordance with the "standard tensile test" described hereinabove, may exhibit a stress at yield of at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> MPa.

The stress at yield may be at most <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> MPa.

Similarly, the formulations according to the present invention, when cured according to the standard curing procedure, and prepared in accordance with the procedure provided in Example <NUM>, may exhibit a strain at yield of at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>%.

This strain at yield may be at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM>%.

Young's modulus, for the inventive formulations cured according to the standard curing procedure, and prepared in accordance with the procedure provided in Example <NUM>, may be at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM> MPa.

This Young's modulus may be at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM> Mpa.

The stress at maximum load, for the inventive formulations cured according to the standard curing procedure, and prepared in accordance with the procedure provided in Example <NUM>, may be at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM> MPa.

This stress at maximum load may be at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM> MPa.

With regard to the break point: the strain at break, for the inventive formulations cured according to the standard curing procedure, and prepared in accordance with the procedure provided in Example <NUM>, may be at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>%.

This strain at break may be at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM>%.

The cumulative energy to this break point may be at least <NUM>, at least <NUM>, or at least <NUM>. This cumulative energy may be at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM>.

With regard to rule hardness, the hardness of each rule was evaluated according to the following procedure:
The rule was cured, and the sample was dimensioned, according to the standard procedure provided in Example <NUM>. The sample size was <NUM>•<NUM>•<NUM><NUM>.

The needle of the hardness-measuring device (Bareiss Germany, HP) was pressed on the top and bottom sides of the sample at three random locations for each side, to obtain the average Shore D hardness. Results are provided in the table below, and are plotted in <FIG>.

As used herein in the specification and in the claims section that follows, the term "proximate to the die surface" and the like, with respect to a rule width, refers to a maximum width of the rule within <NUM> of the rule "tip", distal to the die base.

As used herein in the specification and in the claims section that follows, the term "percent", or "%", refers to percent by weight, unless specifically indicated otherwise.

As used herein in the specification and in the claims section that follows, the term "acrylate" is specifically meant to include sub-species of the acrylate family, including methacrylates and acrylates having a single acrylate moiety, or more than one moiety.

The term "acrylic", with respect to a moiety, is specifically meant to include the various sub-species of the acrylic moiety, including methacrylic moieties.

As used herein in the specification and in the claims section that follows, the term "standard curing procedure", and the like, refers to the formulation curing procedure detailed in Example <NUM>.

As used herein in the specification and in the claims section that follows, the term "standard tensile test" refers to a stress-strain test on samples prepared in accordance to ASTM <NUM>-<NUM>, using an Instron <NUM> (or equivalent) tensile machine, under the following conditions: crosshead speed: <NUM>/min; second crosshead speed: <NUM>/min, and full-scale load range: 5kN. It may be appreciated by those of skill in the art that different operating conditions might be suitable for samples having different mechanical properties.

Claim 1:
A polymeric rule die (<NUM>) for pressure-contacting of a cardboard workpiece (<NUM>) surface, the rule die (<NUM>) comprising:
(a) a die body (<NUM>); and
(b) at least one elongate rule (<NUM>), each said rule (<NUM>) having:
i. a first elongate base surface (<NUM>) adhesively attached to a surface of said die body (<NUM>); and
ii. an elongate protrusion (<NUM>) , distally protruding from said die body (<NUM>), said elongate protrusion (<NUM>) having an elongate die surface (<NUM>), said elongate die surface (<NUM>) including a polymeric material, said elongate die surface (<NUM>) having a contact surface adapted to contact the workpiece (<NUM>) surface;
characterized by:
said contact surface having a length of at least <NUM> and a first width within a range of <NUM> to <NUM>, said rule (<NUM>) having a height within a range of <NUM> to <NUM>;
wherein, following a standard deformation procedure, a standard crease produced by the rule die (<NUM>) exhibits a mean folding force ratio of at most <NUM>%.