WO2014021831A1 - Management of throughput of elastomeric mixes through calendering drives - Google Patents

Description

MANAGEMENT OF THROUGHPUT OF ELASTO ERIC MIXES THROUGH

CALENDERING DRIVES

[0001] The present Invention relates to a method that allows for the -effective management of the throughput of eiastomene mixes processed by a calender set of rolls comprising one or more pairs, of roils that have a nip between them. This may be accomplished_, by properly managing the thickness of the skim as it is processed by the calender as well as its final thickness after exiting the calender. The size of the bank of material that collects In front a nip can also be effectively controlled,

[0002] Calenders are mechanisms that include a series of pairs of rolls through which a substance that is malleable can be run in order to smooth out the- material and form a skim or sheet of uniform thickness, in- the tire industry, calenders are used to process an eiastomenc or rubber mix that is usually extruded and then sent through the calender to create a sheet of rubber or elastomer mix. Between each pair of rolls Is a gap or nip.

through which the material is run as the rolls are rotated. .Depending on a host of processing variables, the sheet will assume some thickness that is proportional to the width of the nip. Often, the material is fed through three sets of rollers and nips in order to create a homogenous and smooth sheet that also has a desired thickness, as s the case for an inverted "L" configured calender as will be described shortly. This sheet is then used to create some portion of the tire, such as the tread of other semi-finished goods used to manufacture and assemble the tire such as belts and carcass plies, etc.

[0003] An illustration of -such a typical calendering system JO is shown in FIGS. 1 and 2. which has three pairs of roils {labeled as roils 12, 14, 1-6, and 18) with a nip between them as well as fifth roll 20, sometimes, referred to as a take-off roller that takes the sheet as it comes off the fourth roll 1.8, The purpose of this rol l is to _.provide tension to the sheet 22 as it exits the calender and to peel the skhn off roller 18, The calender rolls thai are part of a pair rotate in opposite directions or in the same linear direction in the nip area .24 so that material that is fed in to the en trance 26 of the nip is forced through the nip into the exit Inventors: Almira Aleekovie, Daniel Robert l¾ry, Larry S, Satterfield.

area 28 of the nip. For the first pair of rollers, the entrance of the nip is located above the rolls so that material is naturally fed into the nip via .gravity upon startup or just before. Usually, a bank 30 of kneaded material (sometimes referred to as a bourelet by the invenior(s)) collects above the nip of the first pair of rolls so that enough material is present to form an uninterrupted sheet of materia! that can pass through the calendering system. This bank is created by oversupp!ying slightly the- amount of material needed to create the sheet of materia! from a source of the material such as an. extruder. In time, material Is forced downward into the nip by the rotation of the roils.

10004] After exiting the first nip, the materia!, then winds in a counterclockwise direction around the -second roll 14 until It is reaches the third roller 16 where it goes through a second nip. Once it exits it winds in a clockwise-direction around the third roll 16 and then encounters the fourth roil 18 where it goes through the third nip. At this point, the sheet then attaches to the fourth roll where it is rotates in a-counterc!ockwise direction, once more around the bottom and part of the back of the fourth roll and on top of the fifth, roll 20 which is rotated in the clockwise direction and which is biased upwards to place the sheet in tension before it proceeds to a production center where some fire component is made using the sheet of material. This desired path is shown by the solid outline of material whereas an .unintended circulation of material is represented by the da shed arrows as will be described in further detail later.

[0005] Ail the roils or pairs of rolls can be commonly driven by a single motor using gears, chains or belts. In such a case, the speed of all the rolls or of the rolls of a pair can be the same or can be different utilizing some sort of transmissio system such, as a variable speed -ratio reducer between the rolls and the motor. Alternatively, all the rolls can be independently driven using a separate motor for each roll, In that case, electronic- controls are sometimes furnished that allow tight and independent control of the speed of each roll by way of suitable programming by the operator or some other .control algorithm executed by a computer. For an example of roils that are independently driven or that can operate at different adjustable speeds, see U.S. Pat os. 2,333,629; 4,444,361 ; and G.B-. Pat. Nos. 856,454; 620,340.

[0006] An example of a production center that can be fed by a calender .system is depicted by FIG. 3, which is disclosed in U.S., Patent Application Publication No.

2.01 1036485, which Is commonly owned by the assignee of the present invention and whose content is incorporated b reference for all purposes in its entirety. Portions of that application are reproduced herein as follows to describe how the process works and how it Inventors; Aimir Aleekovle, Daniel Robert Rev, Larry S, Satterf d can be used in conjunction with the present invention. It should be noted that this is given by way of an -example of a production center and that the present invention is equally applicable to an manufacture of a. tire component thatrequires a calendering system of any sort Including those that only have a single pair of roils.

[0007] A system 110 for generating a multi-layered ti e component in. accordance -with the methods described in. the '485 application is generally shown in FIG, 3, System 110 generally operates to form a multi-layered tire com onent by winding strips 1 .1 about a building, surface. Because tire component is a wound . product, it generally forms a complete circle (i.e., a. ring). Component is also referred to herein as a band. Also, system 110 generates a sheet 121 from which the strips 141 are formed, and, in particular

embodiments, the sheet 121 remains CQntinnoiiS as it travels, along a closed-loop path to and from a ^'sheet generator 120, Accordingly, system 110 automatically returns any unused sheet material tor reuse by generator 120. System- 110 , generally forms elasiomerie tire components, such as, for example, tread, sub-tread, and cushion gum. it can also create a multi-layered band that is a profiled fire tread band,

jOOOSf In this embodiment, system 110 comprises a sheet generator 120, a cutting assembly 140, a strip applicator assembly 160_» a recovery assembly 170, and a

programmable logic controller (not shown). System 110 ma -also include a roller assembly 130 for directing a sheet 121 from generator 120 to cutting assembly 140. Sheet generator 12:0 generally transforms input material 112 imp a sheet 121, which Is ultimately cut. into strips 141 by cutting-assembly 140. With continued reference to FIG, 3, input material 1-12 is received through inlet 1^'22> and may comprise-new material 112a and/or previously -used material 112b supplied by recovery assembly 170. Afte receiving input material 112, generator 120 forms the input material by any known means such as by a calendering system shown in FIGS, i and 2 and described above into sheet 121, where sheet 121 is formed to any desired width and thickness. Sheet 121 is expelled from generator 120 by way of outlet 124.

(00091 In one embodiment, as shown i FIG. 3. generator 1-20 comprises an extruder. Extruders generally push input material 11_.2 through a die or head, such as by way of a screw. Any extruder known to. one of ordinary skill in the art may be used, by system 110. Generator 120 may also -comprise a calender, in lieu of or in addition to an extruder, which may comprise a pair of rollers positioned in. close proximity to each other to form a gap or nip, through which, input material 1 12- passes to from a sheet 121 (as described above). The resulting sheet 121 includes: a width associated with the Width of the calender. nip. Inventors: Aimira Ateekovie, Daniel .Robert Rey, Larry S. Satterifc!d

[0010] As shown in FIG. 3, a roller assembly 130 maybe located between sheet generator 12 arid cutting assembly 140, Roller assembly 130 generally comprises one or more rolls 132 arranged to form a translation path of sheet 1.21, The take up roller described above in FIGS. 1 and 2 may be considered as such a roll. The particular translation path directs sheet 121 to cutting assembly 140, and may be used to tense sheet .121 as desired. The location of rolls 132 may be adjusted to impart more or less tension on sheet 12.1, which m also provide a means for adjusting the cross-sectional dimensions of sheet 121. One or more roils 132 may be driven, or powered, such as. for example, by a motor, to assist in the translation of sheet 121, and/or adjustment of tension in sheet. 121. i addition, biasing- means such as springs, pneumatic or hydraulic cylinders, etc, -may orce the roll against the sheet to provide tension. Sheet .121 may also be tensed by creating a speed differential between drum 125 and/or cutting drum 152, by increasing or decreasing the rotational, speed of either drum.

[0011] Cutting assembly 140 generally forms strips 141 from sheet 121 for subsequent assembly of the tire band. More specifically, cutting assembly 1 0. utilizes a. plurality of cutting members .142 to cut strips 141. wherein each cutting member 142 includes a cutting: edge 143. Cutting members 142. generally are spaced along a length of sheet 421, and along a. circumference of cutting surface and/or .cutting drum 152. In the embodiment-shown in the FIGURES, cutting members 142 are rotating knives. Rotating knives, -In the embodiment shown, operate similarly to idler wheels, and freely rotate at the direction of the translating sheet 121. Still, rotating knives 142 may be driven by a . motor or any other known driving means. Also, other means for cutting sheet 121 known to one. of ordinary skill in the art may be used in. lieu of rotating knives,, including other non-rotating, knives, blades, or edges.

oll] With general reference to FIG. 3_? system 11.0 also includes applicator assembly 160 for applying one or more -continuous strips 141 to a building surface to form a band.- The one or more- strips 141. are wound about the building surface to form the muHi- layered band. Applicator assembly 160 includes an applicator -drum 162 that transfers one or more strips .141 there from to building assembly 180. To provide adhesion between applicator drum 162 and strips 141, which promotes the separation of strips 141 from, sheet 121, applicator drum 162 may be heated or- cooled. In particular embodiments, applicator drum.162 is maintained at a temperature -at feast 10 degrees Celsius higher than the temperature of sheet 121 and/ or any -strips 141, In other embodiments, applicator drum 162 is maintained at approximately 70 degrees Celsius.- The surface of applicator drum 162 may Inventors: Almira Aieckovie, Daniel Robert Rev, Larry S. Salterfield comprise a smooth surface, which: may be. a chromed or hot ehi'G.med surface, so to provide a smooth,_. capillary-like surface that may promote molecular bonding and/or may operate like a vacuum to facilitate retention of strips .141 thereon. Improved adhesion may also be provided by providing a rough surface, the rough surface providing increased surface area, for improved contact area, and therefore, increased adhesion. Applicator claim 162 may also operate as the cutting drum 152, Further, the temperature controls and conditions, as well as the surface conditions and treatments discussed with regard, to applicator drum 162 above may also be applied, to cutting drum 152 to improve adhesion between drum 152 and sheet 121, Using this system, tread features can_. be built onto a . green or unc-ured tire layer by layer.

(0013) As just described regarding the applicator or cutting, drum, the adhesion of rubber strips to a round and rotating ^' _.surface is apt to occur, Accordingly, when multiple rotating surfaces are present near the exit of the- nip of calender rails, e.g. their respect circumferential -surfaces thai are rotating awa from the ni exit, a sheet of elastomenc mis can bond with either of these surfaces, or partially to both at the same time. This can be a problem during the operation of the calender, but especially during ihe initialization or startup of the calender as an initial sheet needs to be directed, often by an operator, to follow the proper path until the calender has been successfully ^'"threaded"^' and is ready to supply a sheet of material to the desired production center. This requires shut-down of the equipment for safety reasons, which can be: costly.

[0014] Looking back at FIG , 2, the desired path is denoted by the solid outline of material and the unwanted paths by dashed arrows. As can be seen, the first unwanted path can occur when the- sheet follows the first roll 12 where it rotates clockwise away from the exit 28a of the first nip 24a, This can lead it back, to the- top bank 30a of kneaded material.,, creating an undesirable "feedback loop where excessive material will spill of the axial ends of the- roll and down the sides of the calendering apparatus, potentially causing damage- to the apparatus or other equipment by gumming up the equipment, it also interrupts the production of the skim, stopping the production process when supplying it in real time, A. similar situation can occur when the sheet exits the second nip 24b as it can continue to run clockwise on She second roll 14 and into the top bank -of material 30a, After the third nip 24.C. the material can recycle itself back to the second nip 24b, creating unwanted growth of. a second bank 3-0 b of material. Finally, after the sheet comes back around the bottom of the fourth roil 1.8, it can. continue to follow this roll and create a third bank 30c of material near the entrance 26c of the- third nip 24c. Inventors: Almira Alecfcwie, ^'Daniel Robert Key, tatty S, Saiferfieid

[OOiSj Any of these banks of material can become too large and cause the equipment problenis. Even after initially threading the calender, ail three banks can occur due to some small residue sticking to the rolls and collecting near the entrance to the nips over time, thereby causing some small amount of recycling. Also, there is a desired amount of slight 80 oversupply to the first nip that helps to ensure enough material is present for the step

reduction in skim thickness at each nip which creates a full width sheet, that is smooth, homogenous and that has the correct thickness. So, it Is desi rable to control the size of the banks of material but not to eliminate them altogether,

[00:16] Regarding the monitoring of the sfee of the banks of materials, a mechanical 85 method is disclosed in U.S. Pat. No. 3,609,801 and includes a roller that Sits on top of the bank of material and moves^' therewith as it grows, sending signal to a control system so that once the bank gets too large or too small, the control system can vary the amount of rubber supplied to the calender. A more modern technique tor monitoring the size of hanks of material found in calendering can be found in U.S. Pat. No. 6,330,024 thai uses digital 90 imaging technology. Using this technique the size of the bank can be determined, and the amount of material supplied, to the calendering^' device can be adjusted accordingly. Also, this can be done visually.

[0017] The reason elastomeric mixes are tacky wil l now be explained. Suitable compositions for making a sheet for use in tire components such as treads include those 95 rubber compositions having a glass transition temperature within a defined range, said rubber compositions being based upon a diene elastomer, a plastlcking system and a cross- linking system, The diene elastomers or rubbers that, are useful for such rubber

.compositions are understood to be those elastomers resulting at least la part, i.e., a homopolymer or a copolymer, from diene monomers, i.e., monomers having two double

100 carbon-carbon bonds, whether conjugated or not,

[0018 j ^'In summary, tyical diene elastomers include highly unsaturated diene.

elastomers such as po!ybutadienes (BR), polyisoprenes (1R), natural rubber (NR.), butadiene copolymers, isoprene copolymers and -mixtures of these elastomers. Such copolymers include butadiene/styrene copolymers (SBR), isoprene/hutadiene copolymers

10.5 (B1R), isoprene styrene copolymers (SIR) and isoprene/butadiene styrene copolymers

(SBIR). Suitable elastomers may also include any of these elastomers being funetionalized elastomers.

[0019] lis addition., the elastomeric composition, disclosed herein may further include: reinforcing filler. Reinforcing fillers. are added to, inter alia, improve the tensile strength .Inventors.: A antra Aleckovic, Daniel Robert Rey, Larry S. SaUerfiefd

I J 0 and wear resistance of the material. Any suitable reinforcing fi tier may be suitable for use in compositions disclosed herein including, for example, carbon blacks and/or inorganic reinforcing fillers such as silica, with which coupling agent is typically associated.

Inorganic reinforcing .fillers may take many useful forms including, for example, as powder, microbeads, grannies, bails and/or any other suitable form^' as well as mixtures 1 13 thereof. Examples of suitable inorganic reinforcing .filters include mineral fillers of the si liceous type, .such -as silica (Si02), of the aluminous type, such as alumina (A103) or comb in at ion thereo f.

[0020] for coupling the inorganic reinforcing filler to the diene elastomer, a. coupling agent that is at least bifiinctional. provides a sufficient chemical and/or physical connection

120 between the inorganic reinforcement filler and the diene elastomer. Examples of such coupling agents include biftmciional organosilanes orpolyorganositoxanes. Such coupling agent^'s and their use are wet! known i the art. The coupling agent ma optionally be grafted beforehand onto the diene elastomer or onto the inorganic reinforcing filler a is known. Otherwise it may be m xed into the rubber composition in its free or non-grafted

125 state.

(0021] in addition, to the diene elastomer and reinforcing ill ter, particular embodiments of the rubber composition disclosed herei may further include a ptasticizing system. The ptasticizing system may provide both an improvement to the processabi !ity of the rubber mix and/or a means for adjusting the rubber composition's glass transition temperature

130 and/or rigidity. Suitable plasticizing systems may include a processing oil, plastleizing resin or combinations thereof. Other plasticizing systems are known.

[0022] Also, the rubber compositions disclosed herein may have and. be cured with any suitable curing system including a peroxide curing system or a sulfur curing system, many of which are known in the art. Other additives can be added to the rubber compositions

135 disclosed herein as koown in the asi. Such additives may include, for example, some or all of the following: antidegradants, antioxidants, fatty aelds. pigments, waxes, stearic acid and zinc oxide,

[0023] These constituents, notably the polymers used in the e!astomeric mix. make the sheet sticky or have tack. Increasing the amount or type of certain ingredients such as 140 pigments, fillers, additives, and plastleizers can increase tack. Also, some polymers have inherently more tack than others. Consequently,, different mixes have more tack than others and can therefore be more prone to the problems .just described. Inventors: Ahnira Aleekovk, Daniel Robert Rey, Larry S. Satter!Iekl:

[0024] A can be imagined, a number o methods have been devised to help manage unwanted sticking of the sheet of materia! to calender rolls. Some methods have been

3 5 already described above and include providing a temperature or surface finish differential between the- two soils that define a nip so that the sheet, of material is prone to follow one versus the other. Also, surface treatments that decrease adhesion to the roll to which adherence is undesirable after the sheet exits: the ip can be applied to that roll. Such treatments include TEFLON, aikanolamines. alkylene glycols, and poiyalkylene glycols

15.0 (see U.S. Pat. No, 3,841,899}. In published Japanese Patent Application Publication No. jP 201838A, there is disclosed a. method of continually applying a release agent on a roil using a soft roll onto which the agent is sprayed that rubs against the roil for solving sticking problems associated with that roil. Finally, the use of scraper blades is often used^' to prevent the unwanted, .recycling of material that can contribute to bank growth over time

! 55 (See Jap. Pat. Application Publication No, 08- i 97558 A and U.S. Pat. No. 4221 ,022 for examples). Also, the use of scraper blades to prevent the improper threading of a sheet processed by a calender processing eiastorneric mixes, preventing it from recycling to. the entrance of the nip thereby a iding in the start-up of a calendering process is also known (see col. 3, lines 5-10 of U.S. Pat. No. 4,871,409)..

160 f0025] However, .all these methods, have drawbacks. Concerning maintaining the temperature of the rolls, it is necessary to maintain consistency the entire- ime the calendering apparatus is running, which could be difficult depending on ambient conditions or can be beyond t e: temperature permitted by the m-ix, Also, this method could delay start-up until the roils reach the desired temperature. Surface treatments that are applied to

165 rolls such as disclosed in U.S. Pat. No. 3,841,800 can wear off over time, which adds cost to reappl the treatment and possibly som downtime for the equipment and bad for the product as they end up in the mix. Continuously applying a release agent can be both expensive, messy and may cause the agent to seep into the material causing a degradation of the properties- of the -sheet of material. Finally, scraper blades do not allow for the

170 automatic, hands-free threading of .a calender -processing an eiastorneric mix as admitted by the prio art. (see comments regarding US. Pah No. 4,871,409 above),

[0026] Another important issue with calenders is maintaining^' the desired thickness of the skim, especially after it exits the calender. As can be imagined, this can be- affected by the sticking issues previously discussed as- stuck. residue can detract or add minute amounts

.175. of material. A lso, a host of other process variables can cause variations in the thickness of the skim, The thickness can he monitored by any means known in the art, including inventors: Almira Aleckovic, Daniel Robert Rey, Lurry S. Satterfteld manual measurement x-rays (see Chinese ^'Pat. No, CN2150989} including a single point radiation hack scatter gauge (see GB 14398Q7A), and ressing in the ni (see

DE 1 Q 1 12296 A), and a compamtor (see GB I f 90802A). In some cases, it can be found that the thickness is too great, if so, one solution is to stretch the skim by speeding, up the rate at which the skim is removed from the calender (see Chinese Pat, No, CN2150989 for example). Other methods for adjusting .the skim, thickness include adjusting the gap between the rollers (see JP621.5131 1) as well as the amount of .material fed into the calender and its rate of output. However, each of these methods have -disadvantages such as -requiring- ore expensive equipment, or ove-rsuppiying or starving the production center to which it is desired to feed the skim when supplying the skim in real time.

[0027] Accordingly, a improved method for controlling the size of banks of material or the skim thickness is warranted. More particularly, such a method that does not require significant increase in cos would he helpful, it would be-also desirable if the proposed solution worked on the stickiest of eJastomeric mixes. Furthermore, a method^' that helped maintain the desired calendering rate of skim produced consistently would be ideal.

SUMMARY QF THE INVENTION

{0028] Aspects and advantages of the invention wi ll be set forth in part in the following description, or may be obvious from the description,, or may be learned through practice of the invention.

[0029] The present invention includes a method for operating a calendering system that processes elasto eric m ixes for producing a skim with a desired ^'thickness range- at a desired calendering rate -comprising two pairs of rolls having- a nip between said rolls, thereby forming a first nip and a second nip found downstream from the first nip, said calendering system having at least one bank of ^'material found prior to a nip that has a desired size range. The method comprises the following steps:

[0030] monitoring the size of a bank of material located before the second nip or the thickness of the skim before or after the second nip:

[0031] determining that the thickness of the skim is- outside a desirable range: or

[0032] determin ng that the size of the bank of material is outside a desirable range; and

altering the speed of a single roll that is found upstream from said location where the skim thickness has been determined to be out of the desirable range or where said size of said Inventors: Almira Aleckovlc, Daniel obert Rey, Larry S. Satterikld

200 bank has been determined to be outside of the desirable range to change the thickness of the skim or the size of the bank of materia!.

[00331 The method may further comprise: the step of providing at least three pairs of roils with first, second and third nips found between each successive pair, wherein there is a bank of material found before the second nip having a desirable size range and another

205 bank of material found before the third nip having a desirable size range and wherein said monitoring step comprises measuring the skim thickness in one or more places before the second or third nip or measuring the size of the banks of material found before the second and third nips. The determining steps may comprise finding a local skim thickness to be outside of the desirable range or determining that the size of a bank of materia! is outside a 10 desirable range and said speed altering step may comprise changing the speed of a roil Upstream of where the skini thickness or bank size needs to be adjusted.

.1_.0034^' j In some embodiments after the skim exits the ip, the speed altering step comprises altering the speed of a ro!i that is not in significant contact with the skim after the skim exits the- nip,

215 [0035] in other embodiments, the speed alteri g step comprises slowing u a roll so that the thickness of the skini is reduced, in such a case, said roll that is slowed down may be part of the last pair of roils, said roil, not being in significant contact with the skim after skim exits the last nip and said roll is used to adjust, the final thickness of skim as the skim exits ^'the calender apparatus. In other eases, the speed altering step comprises slowing

220 down a roll so that the size of the bank of material found downstream from said roll is reduced.

{0036] When employing this method, it is advantageous when the speed altering step does not make a roll or pair of rolls run at a rate that is outside of (he ranges that have been predetermined to be suitable for running continuous production without risking_, unwanted

225 sticking, or misrautihg, or breakage of the skim. However, some slight deviation from these preferred ranges may be allowable for limited periods of time. Any of the embodiments discussed herein may be able to work without needing to oversupply or starve a production center in real time. Also, any of the embodiments discussed herein may be- used on an elastomeric mix having imionene content or having a total PHR of

230 piastieizer content (including oil and resin) of 15% or more

}0037] These and other features, aspects and advantages of the present invention will^' become better understood with reference to the following descript ion and appended claims. The accompanying drawings, which are incorporated in and constitute a. pari of this Inventors: Aimira Aleckovic, Daniel Robert Rcy, Larry S_* Satterfield specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0038] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skil! in the art. is set forth in the speeiilcation, which makes reference to the appended figures, in which:

[00.39] FIG. I is a perspective view of standard calendering apparatus,

[0040] FIG. 2 is a side view of the rolls of the calendering apparatus shown in FIG. 1 being removed from the apparatus for enhanced clarity.

[0041] FIG. 3 shows a production center that, uses calendered sheet for making strips that are applied to a green, tire to create the tread of a tire.

[0042] The use of identical or similar reference numerals in different-figures denotes identical -or similar features.

DETAILED DESCRIPTION OF THE INVENTION

(00431 For purposes of describing the invention, reference now will be made in detail to embodiments and/or methods of the invention, one or more examples of which are- illustrated in or with the drawings_* Each example is provided by way of explanation of the- invention, not. limitation of the invention, in fact, it will be apparent to those skilled in the art thai various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention, For instance, features or steps illustrated or described as part of one embodiment, can be used with another embodiment or -steps to yield, a stiil further embodiments or methods. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0044] As used herein, "elastomeric mix" refers to a variety of possible compositions - natural and synthetic - as may he used to construct various portions of a tire. A more:

complete description of these variants is found above in the BACKGROUND OF THE

INVENTION.

[0045] As used herein, "roller speed" refers to the linear speed of a roller at its circumference and not its angular rotation or RPM. It is to be understood that the controllers for most calendering systems can translate linear speed to RPM easily so that a user typically inputs the desired linear speed of a roll. When referring to these speeds in Inventors: Almira Aleekovie, ^'Daniel Robert Rey, Larry S, Satierfieid

240 percentages, it is to be understood that they represent- percentages, of the desired linear production rate- of the skim produced by the calendering system. Typical calendering rates range from S to 100 meters per minute and have bees? tested successfully by the inventors with regard to the present invention,

[0046] Upon initialization- or startup, the inventors found it beneficial for the

245 processing of some mixes to slo down the roll to which It was desired for the skim to follow as compared to the other roil with which it. forms a nip. For example, it may be beneficial to slow down second roll 14 as compared to first roll 12 by as much as 5 to 10 percent. Likewise, it might be beneficial to slow down third roil 16 by 5 to 10 percent as compared to second roll 14, Finally:, hands-free threading may be. accomplished by 250 slowing down fourth roll 18 by 5 to 10 percent as compared to the third roil 16. in other words, the ratios of the speeds of the rolls upon startup ^'before an elastomeric. mix is sent through the first hip 24a, would be as follows:

[0047] R14= 90 to 95% ofR12; R1.6- 90 to 95% of R14; R18= 90 to 95% of R16. In such a case, the skim will thread itself appropriately without following the wrong roll after

255 it exits any of the nips. The inventors have tested this on the stickiest m ix (later referred to as mix I ) they have encountered, which has 8.7% PHR of a polymerized oil obtained from citrus fruits (Lunoneiie) and that is also heavily loaded with other pkstielzcrs and found that it allows the mix to be threaded hands-free, The skim can then supply a production center as previously described.

260 |0048^'[ After startup, the inventors have found it useful to reverse these roll speed

differentials to help maintain the proper routing of the skim. This was tested on four different mixes using different speed differentials and it was found that it decreased the probability of misrouting, unwanted sticking and skim breakage, ail of which may result in downtime of the calendering apparatus and production center In order to clean up and

265 thread the system once again. Table 1 gives this information in tabular format below. Note thai it is the type of -resin used and the overall total piasticker content that contributes^' most to the tack of the elastomeric mixes and these mixes were chosen as being quite tacky.

TABLE 1

Mix Resin Total R12 R 14 Rifi R18 R20

# PHR Piasttcizer (roll (roll (roil (roll (roil

PHR speed as speed as speed speed speed

(includes oil %) % ) as %) as ) as %) inventors: Almira Aleckovic, Daniel Robert Rey, Larr S. Satterfield and resin)

1 S.8%¹ 21 ,8% 3 72 85 100 150

2 14,4%^J 16,7% 95 100 105 n o 1 15

3 U,5%^}- 16.9% 95 100 105 10 1 1 5

4 4.4%^! 19,2% 50 60 SO 100 130

Umonene resin ^" Aliphatic Hydrocarbon resin

[0049] As can be seen, a speed differential ranging fromS to 20% was used between the pairs of roils of the calendering apparatus to maintain continuous production for these mixes.. However, the inventors have encountered situations where as much as a 25% overdrive was used to prevent the mix from following the wrong roll during production. {005^'Oj The inventors have theorized why reversing the speed differentials from startup to production works. Upon startup, there is no: tension on the skim so its tendency to stick Is a matterof the bonding force of the skim in the nip area to one roll versus the other. By slowing down a roil, the bond forces are subjected to less shear force as compared to the roll rotatin more quickly, causing the skim to follow the slower moving roll. Once production is commenced after threading, the skim i under tension so it is effective to increase the speed of the roll to which the skim is adhered as this increases the tension in the skim, helping to overcome the bond forces between the skim and the roll to which it Is undesirable for the skim to stick. OF course, ^"it is contemplated that this ^'might not work for all situations and for all types of eiaxtomerse mixes,

[0051 ] As mentioned previously., the management of the throughput of the calender is somewhat connected to sticking issues so the inventors theorized that by adjusting roll speeds, the size of the banks of materia! as well as skim thickness could be adjusted in addition to helping solve the sticking issues. Testing of the mixes above as well as other mixes has shown that adjusting the speed of the appropriate roll at the appropriate time can effectively manage these throughput variables as well. For example, the typical, skim thicknesses for which the present invention has been successfully tested ranges from 1 to 1.6 ram on average but it is contemplated _.that this might work for other skint thicknesses as well. For example, thicknesses as low as .9 mm and as high as 1 ,8; mm have been successfully tested. For these skim thicknesses, a .1 to .2 mm change In thickness can be obtained by simply speeding up or slowing down the roll to which it is not desired for the skim to. follow, or in other words, the roll which does not have significant contact with the Inventors: Alniira A!eckovic, Daniel Robert Rey, Larry S. Sstterfield

skim. By speeding up this roll, the^' local thickness of the skim just downstream of the roll

295 can he ^'increased. By slowing down this roil, the local thickness of the skim can be

decreased. This also has- the effect of increasing or decreasing the size of the bank that fol lows behind the roll to which the: speed adjustment just mentioned is made.

[0052] So, if the thickness of skim locally after the first nip is too low or the second bank of material is too small,, then the speed of the first roll can: be Increased to increase the

300 skim thickness locally, which .also has the effect of increasing the size of the second bank of material. On the. other hand, If the thickness, of the skim locally after the first nip is too high or the second bank of material is too great, then the speed of the first roil can be decreased to decrease the thickness of the skim or to decrease the size of the second bank. Of course, this logic holds true for other nips and rollers in a fairly consistent manner, The

305 final skim thicknes is proportional to the final nip thickness and is dependent on material properties and other process variables. The output speed of the ski m is determined primarily by the speed of the last roll with which the skim makes significant contact, j 0053) i is further contemplated in cases where the skim thickness is not a concern for the operator, that either roll of a pair that, is found upstream .of a bank of material can be

310 sped up or slowed down if desired to alter the size of the bank. Likewise, airy of these adjustments could be implemented using an algorithm in the electronic controis system. Of course, one skilled in the art would have to be careful when adjusting the throughput variables not t stray too much or too long from the speeds listed above considered^' useful, for sticking and breaking issues of the skim for particular mixes, for fear of creating a

3 15 failure of the skim or misfou_.ting of the skim, which could lead to downtime for the

equipment.

{0054] The apparatus used to test the present invention had roll diameters for the first through fourth rolls of 250 mm ^' and the roil diameter for the fifth roll was 150 mm but it is contemplated that this invention will work with other roll diameters as it is the differential 320 in relative linear speeds of the surfaces of the roll that creates the desirable forces that direct the proper routing of the skim at various times including Startup and productio as well as the desired management, of the throughput of the system. Testing has revealed that this invention works at typical calendering rates but it is contemplated that it will work on other rates as well.

325 [0055] Furthermore, the present invention has been .-accomplished: without requiring adding equipment, which keeps the cost of the equipment desirably low. However, it is contemplated that the present invention could be implemented by using any of the methods Inventors: Al ira Aleckovic, Daniel Robert Rev, Larry S. SaLterfie!d already known and thai will be devised in the art to help- manage unwanted sticking in calendering systems: as well as managing the throughput of the system, including those, that add additional equipment. It is further . contemplated that t e. equipment could be scaled up or down, to produce skims havin different target thicknesses, greater or lesser compensation in thickness, well as different rates of throughput.

[0056J While the present subject matter has been described In detail with respect to specific exemplary embodiments and methods thereof, it. will, be appreciated that those skilled .in the art. upon attaining -an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way -of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.

Claims

Inventors-: Almira Aieckovic, Daniel Robert Roy, Larry S. Satteriiekt WHAT IS CLAIMED IS:

1 , A method for operating a -calendering system that processes eiastomeric mixes for producing a- skim with desired thickness range a a desired calendering rate comprising. two pairs of -.rolls having a nip between said rolls, thereby forming a first -nip nd a second nip found downstream from the first nip, said calendering system further comprising at least one bank of material found prior to a nip that has a desired size range, said rolls being capable of rotating at various speeds, said method comprising the following steps;

monitoring the size of a bank of material located, before the second nip or the thickness of the skim before or after the second nip:

determining that the thickness of the skim is outside a desirable range: or determining that the size of the bank of material is ou tside a desirable range; and altering the speed of a single roil that is found upstream from said location where the thickness has been determined to be out of the desirable range or where said size of said bank has been determined to. be outside of ti e desirable .range to change the thickness of the skim or the size of the bank of material,

2, The method of claim 1 which further comprises the step of providing at least three pairs of roils with, first, second and thi rd nips found between each successive pair, wherein there is a bank of -material having a desirable size-range found before the second nip and another bank of material found before the third nip having a desirable size range and wherein said monitoring step comprises measuring the skim thickness in one or snore places before the second or third nip or measuring the size of the banks of material found before the second and third nips and said determining steps comprise finding. local skim thickness to be outside of the desirable range or determining that the size of a bank of materia! is outside a desirable range and said speed altering step comprises changing the speed of a roll upstream of where the skim thickness or bank size needs to be adjusted.

3, The method of .claim 1 wherein said skim exits a nip and said speed altering step comprises altering the speed of a roll that is not in significant contact with the skim after the skim exits the nip-. Inventors: A-lmira Aleckovie. Daniel Robert Rey, Larry S. Satterfiel^'d

4. The method of elairti 1 herein said speed altering step comprises slowing up a roil so that the thickness of the skim is reduced.

5. The method of claim 2 wherein said speed altering step comprises slowing down -a roll so that the size of the bank of material found downstream from said roll is reduced.

6. The .method of claim 4 wherein said roll thai is slowed down is part of the last pair of rolls, said roil not being in significant contact With the skim after skim exits the last nip and said roll is used to adjust the final thickness of skim as the skim exits the calender apparatus.

7. The method of claim I wherein said speed altering step does not make a roil or pair of rolls run at a rate that is outside of ranges- that have been prede termined to be suitable For running continuous production without risking unwanted sticking, or misrouting, or breakage of the skim,

8. The method of claim 1 wherein said speed altering step changes the thickness of (he. -skim by , 1 to 2 mm.

9. The .method of claim 1 wherein said speed altering step comprises speeding up a roll to increase the thickness of the skint.

1 . The method of claim 1 wherein said calendering system produces a skim having a thickness thai ranges from 1 to 1.6^' mm.

1 1. The method claim 1 wherein said calendering rate ranges from 5 to 100 meters per minute,

12. The method of claim 1 wherein said rolls have a. diameter that range from 150 to 250 mm.

13. The method Of Claim. I wherein, the elastonierie mix being processed has linionene content. Inventors: Almira Aleckovie-,. Daniel Robert R.e , Larry S. Safterfteld

14. The- method of claim 1 wherein the e!astomeric mix being processed has at least 15% FHR total, plasiicixer content

15. The method of claim 1 wherein said method is accomplished without needing to starve or oversupply a production center in real time.