EP0838269A1 - Rolls having release coatings, a method for applying a release coating to a roll, and a method of transporting a viscid web - Google Patents
Rolls having release coatings, a method for applying a release coating to a roll, and a method of transporting a viscid web Download PDFInfo
- Publication number
- EP0838269A1 EP0838269A1 EP96117020A EP96117020A EP0838269A1 EP 0838269 A1 EP0838269 A1 EP 0838269A1 EP 96117020 A EP96117020 A EP 96117020A EP 96117020 A EP96117020 A EP 96117020A EP 0838269 A1 EP0838269 A1 EP 0838269A1
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- EP
- European Patent Office
- Prior art keywords
- roll
- release coating
- acrylated
- coating
- release
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/50—Multilayers
- B05D7/52—Two layers
- B05D7/54—No clear coat specified
- B05D7/546—No clear coat specified each layer being cured, at least partially, separately
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
- B05D3/061—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using U.V.
- B05D3/065—After-treatment
- B05D3/067—Curing or cross-linking the coating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
- B05D3/068—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using ionising radiations (gamma, X, electrons)
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/36—Guiding mechanisms
- D21F1/40—Rolls
Definitions
- the field of this invention is finished coatings for rolls used in industrial applications, and more particularly, rolls having release coatings, methods for making such coatings, and methods for coating rolls.
- the field of this invention also relates to machine elements used to transport and process a viscid web and, a method for transporting such a web.
- Covered rolls are used industrially in demanding environments where they are subjected to high dynamic loads and temperatures. Covered rolls are used not only for transporting the material under process, which is in the form of a travelling web, but also for processing the web itself into a finished product.
- Bowed rolls are a particular kind of machine element used to correct distortions and similar problems by distributing lateral tension evenly across a travelling sheet material. For example, bowed rolls are used to spread out or expand the travelling web for the purposes of maintaining width, eliminating wrinkles, eliminating baggy centers or slack edges. Bowed rolls are also used to control felts by maintaining their width, openness and seams, and to eliminate interleaving of individual slit webs on winders.
- Press rolls are yet another kind of machine element used in nip presses. Press rolls process the travelling web by compressing the web at the nip. Typically this is done to remove liquids from the web, e.g., dewatering presses, or to eliminate high and low spots in a finished product, e.g., finish nip presses.
- Bowed rolls with elastomeric sleeves and press rolls with compliant elastomeric covers are machine elements used in applications where the web under process is coated with surface enhancing materials that are tacky and subject to transfer to any surface in contact with the web.
- surface enhancing materials that are tacky and subject to transfer to any surface in contact with the web.
- the transfer of viscid materials from the web to the surface of the roll results in the degradation of the roll's surface and the web's surface. Therefore, it is desirable to have such rolls coated with a material that is, inter alia, self-cleaning, i.e., has high release properties.
- Rolls covered with release coatings prevent excessive sticking which ultimately allows the "release" of the viscid material from the roll surface.
- the flexing surfaces of bowed rolls and press rolls must have good coating release properties, low coefficients of friction, high flexibility, and good abrasion resistance.
- the materials that are presently being used to cover these machine elements are Teflon shrink tubing, sintered Teflon polymer coatings and silicones. These coatings are expensive, subject to excessive wear rates, and exhibit poor adhesion to substrates. Often, they are rendered useless by minor cut damage from the mechanical removal of the web coating material which adheres to the Teflon polymer, and must be removed manually. Thus, the need exists to develop rolls with coatings that are harder, have lower coefficients of friction and improved release properties, with lower wear rates than present day covered rolls.
- the problems caused by prior art coatings, are reduced in accordance with the present invention through the application of a release coating to the surface of a roll or machine element.
- the coating of the present invention is harder, and has a lower coefficient of friction, better release properties and wear rates than those of Teflon polymers.
- Another object of this invention is to provide a method of coating a machine element with a release coating.
- Another object of this invention is to provide a method of curing the coated surface of a machine element with Electromagnetic Wave Energy.
- Another object of this invention is to provide a method of curing the coated surface of a machine element with Electron Beam Bombardment.
- Another object of this invention is to provide a method of curing the coated surface of a machine element with Ultraviolet Light Radiation.
- Another object of the present invention is to provide a coating for a machine element that is hard enough to be abrasion resistant while having high release properties.
- Another object of the present invention is to provide a coating for a machine element that is abrasion resistant while, having a low coefficient of friction.
- Another object of the present invention is to provide a coating for a machine element that has improved release properties.
- Another object of the present invention is to provide a coating for a machine element that has lower wear rates than prior art coatings.
- Another object of the present invention is to provide a coating for a machine element that has wear rates that are lower than that of a Teflon polymer.
- Another object of the present invention is to provide a coating for a machine element that is abrasion resistant.
- Another object of the present invention is to provide a coating for a machine element that is abrasion resistant yet complaint enough to be applied to machine elements requiring flexible surfaces.
- Another object of the present invention is to manufacture covered machine elements having release coatings applied as a liquid composition of 100% solids and/or solvent thinned solids.
- Another object of the present invention is to apply a release coating to machine elements located on site, i.e., at the user's facility.
- Another object of the present invention is to provide a new and improved roll having better release properties.
- Another object of the present invention is to provide an improved method of processing a viscid web using rolls with improved release properties.
- Another object of the present invention is a method of applying a release coating utilizing a minimum of solvents.
- FIG. 1 is a perspective view illustrating the application of the adhesive coating to a machine element in accordance with the present invention.
- FIG. 2 is a perspective view illustrating the step of curing of a final release layer on a machine element to form a release coating in accordance with the present invention.
- FIG. 3 is a sectional view illustrating a machine element covered with the release coating in accordance with the present invention having a multiplicity of release layers applied over an adhesive substrate layer.
- FIG. 4A is a sectional view illustrating a nip press having a lower cylindrical roll covered with the release coating of the press invention.
- FIG. 4B is an expanded sectional view of the encircled area in FIG. 4A illustrating how the flexible release coating of the present invention can withstand a nip deformation.
- FIG. 5A is a plan view of a bowed roll illustrating an elastomeric roll cover coated with a release coating in accordance with the present invention.
- FIG. 5B is partially sectioned view of a bowed roll illustrating the adhesive and multiple release layers in accordance with the release coating of the present invention.
- FIG. 6A is a side view illustrating a bowed roll covered with the release coating in accordance with the present invention.
- FIG. 6B is a diagram illustrating the placement of bowed rolls in processing a viscid web in accordance with the present invention.
- FIG. 7 is a perspective view illustrating the application of a release coating to a machine element in accordance with the specific example of the present invention.
- FIG. 8 is a diagram illustrating how a bowed roll located in spaced relationship with press rolls and a size bath are used to coat paper in the paper making industry.
- FIG. 9 is a diagram illustrating a system of machine elements used to transport a viscid web in the paper making industry.
- FIG. 10 is a diagram illustrating a coating process in the paper making industry.
- FIG. 11 is a diagram illustrating a system of machine elements used to transport and laminate two viscid webs in a paper making laminating process.
- a roll having a release coating the associated method for making the coating and applying it to the roll, and a method for transporting a viscid web, are described in their broadest overall aspects with a more detailed description following.
- the release coating of the present invention is a composite coating, comprising multiple layers of release coating applied over an initial adhesive layer.
- a liquid composition of 100% solids and/or solvent thinned solids is prepared from what is essentially acrylated epoxy, acrylated urethane and acrylated monomer. Then the adhesive mix is applied to form an initial layer on the machine element utilizing conventional methods, such as a sprayer.
- the release coating of the present invention comprises the addition of acrylated polysiloxane to the adhesive mix which produces a liquid phase reaction of the acrylated polysiloxane and acrylated epoxy, thereby creating a suspended precipitate of epoxidized polysiloxane in a predominantly polyurethane acrylate and acrylated monomer solution.
- the release coating is a liquid composition of 100% solids and/or solvent thinned solids prepared to form a pre-reacted solution that is essentially an epoxidized-siloxane matrix in acrylated urethane and acrylated monomer. Then the pre-reacted solution is applied over the adhesive layer on the machine element utilizing conventional methods, such as a sprayer.
- the release coating, including the initial adhesive coating, of the present invention can be applied to machine elements located at end-users' facilities, thus reducing manufacturing costs and facilitating emergency repairs.
- the adhesive and release layers can either be prepared concurrently in separate mixing vats or consecutively by adding the acrylated polysiloxane subsequent to the application of the initial adhesive layer.
- the adhesive and pre-reacted release coatings can be applied to flexible or rigid substrates, such as, bowed rolls, press rolls or carrying rolls.
- both the adhesive and release coatings can be cured using Electromagnetic Wave Energy in the wave lengths ranging from about 5500 ⁇ . through 006 ⁇ , i.e., long wave ultraviolet down to short wave gamma rays.
- Electron Beam Bombardment can be used to cure the coatings without the use of photoinitiators.
- TABLES 1 and 2 summarize the chemical ingredients used to create the liquid oligomers for the adhesive and release coating layers, respectively. As used throughout this specification and the claims, all percentages are by weight unless otherwise specified.
- 2 Phenoxyethyl Acrylate and Tetraethylene Glycol Diacrylate and 1,6 Hexanediol Diacrylate are polyacrylates that comprise the acrylated monomer.
- Cycloaliphatic Bis A epoxy diacrylate is an example of a commonly used acrylated epoxy.
- Urethane Diacrylate is combined with 1,6 Hexanediol Diacrylate to lower viscosity in the acrylated polyurethane.
- Isobutyl Benzoin Ether is an example of a commonly used free radical initiator, while a Triarylsulfonium Hexaflouroantimonate salt is commonly used as a cationic photoinitiator.
- Epoxidized Novolac is an alternative epoxy which imparts further abrasion resistance and hardness to the final product, if so desired, as for example in a press roll.
- Tertiary amines are additive adjuncts to photoinitiators which extend the curing beyond the Ultraviolet Cure Phase.
- a Methacrylate, such as Glycidylmethacrylate, for example, can be used as an alternative highly reactive monomer, and when added, Flourinated Alkyloxylate Imparts additional release properties to the coatings.
- a coated machine element of the present invention 9 to 26 by percentage weight acrylated epoxy, 10 to 35 by percentage weight acrylated urethane, 8 to 24 by weight acrylated polysiloxane, 28 to 52 by percentage weight acrylated monomer, and 2 to 8 by percentage weight of cationic and free radical photoinitiators are initially mixed together to form a mixture of liquid oligomers in a mixing vat.
- the release coating of the present invention comprises oligomers of acrylated epoxy, acrylated urethane, acrylated siloxane and acrylated monomer.
- acrylated epoxy and acrylated urethane components which provide abrasion resistance properties to the coating while the acrylated urethane and acrylated monomer components add compliance and flexibility.
- the epoxidized siloxane precipitate further imparts hardness and high release properties to the coating.
- Photoinitiators are added to the oligomers to cross-link the pre-reacted solution upon the application of Electromagnetic Energy.
- Electromagnetic Radiation of a machine element covered with the release coating of the present invention causes the photoinitiators to generate free radicals and cationic particles which initiate the formation of cross-linking bonds among the polymers and the siloxane.
- photoinitiators can be used as described in the text, "Radiation Curing Science and Technology,” Edited by S. Peter Papas, (1992 Plenum Press), the teachings of which are hereby incorporated by reference.
- FIG.1 illustrates how the adhesive coating of the present invention is applied to a roll 10 mounted rotatably in bearings 11 and 12.
- Arrow 13 indicates the direction of roll 10, which is arbitrary.
- a traverse carriage 1 travels back and forth alongside roll 10. For purposes of illustration, traverse carriage 1 is shown moving in the direction of arrow 2.
- Mixing vessel 3 which contains the oligomers comprising the adhesive coating, and ultraviolet lamps 6 are mounted on top of traverse carriage 1.
- Sprayhead 4 applies liquid adhesive coating 5 to coat roll 10 to form a first layer 14 for subsequent bonding of additional release coating layers thereto.
- Ultra-violet lamps 6 radiate long wave-length Electromagnetic Energy 7 to effect a partial cure of the adhesive layer 14. This creates good adhesion between the initial adhesive layer 14 and roll 10, and provides a partially reacted reactive film 15 on the outer surface for subsequent bonding with additional layers of release coating.
- FIG. 2 shows how a roll 10 of the present invention is finally cured with ultraviolet lamps 5 which radiate Electromagnetic Wave Energy 6. Arrow 13 indicates the rotational direction of roll 10, which is arbitrary.
- FIG. 2 further shows symbolically how final layer 16 is cured to form a finished release coating 17 which is a matrix composed of hard sites of cross-linked Epoxidized Polysiloxane Acrylate dispersed in a flexible lower modulus binder of cross-linked polyurethane acrylate and acrylated monomer.
- Electromagnetic Wave Energy transparent reinforcing fillers may be used to increase individual coating film thickness and reduce production costs.
- FIG. 3 shows one embodiment of the present invention is a cylindrical machine element covered with multilayers of release coating.
- Metal roll 10 is coated with an initial adhesive layer 11 that has been partially cured. This is followed by the application of multiple layers of release coating containing polysiloxane, layers 12 through 16, until a flexible, abrasion-resistant release layer of desired thickness is formed.
- the final coating comprised of all layers is cured with more intense and shorter wave length energy.
- multiple coating layers and multiple frequencies of wave energy are employed to cure the coatings in order to achieve optimum adhesion to substrates combined with optimum release, flexibility, hardness, low friction, and abrasion resistance of coatings.
- the degree of flexibility or rigidity of the cured coating can be controlled by the percentages of acrylated epoxy and acrylated urethane used in the solutions.
- the reacted liquid phase of the coating contains 1-4% of a combination of free radical and cationic particle generating photo-initiators which react with electromagnetic wave energy (e.g., ultraviolet light) to effect a hard cure of the liquid coating.
- the initial adhesive coat 11 is composed of acrylated polyurethane, acrylated epoxy and acrylated monomers.
- the subsequent additional multiple layers, layers 12-16, contain the epoxidized polysiloxane precipitate matrix suspended in polyurethane acrylate and acrylated monomer.
- This combination provides extremely good adhesion to substrates combined with a thick multi-layered coating with good hardness, and release properties throughout the depth of the coating, instead of the poorly adhered silicone rich surface which results from small additions of polysiloxane, 0.5-2% by weight for example, and which does not last long in a web processing application.
- FIGS. 4A and 4B show a nip press 10 having upper and lower cylindrical machine elements 1 and 2 respectively.
- the lower machine element 2 is coated with a flexible release coating 4 of the present invention.
- FIG. 4B which is an enlargement of encircled area 3 in FIG. 4A, shows lower machine element 2 coated with the release coating of the present invention comprising initial adhesive layer 11 and multiple layers of release coating 16 which have been applied as described above.
- FIG. 4B also shows how the release coating of the present invention must have enough flexibility to withstand a nip deformation 20.
- FIG. 5A shows generally how a bowed roll 10 consists of three basic elements.
- a non-rotating axle 12 that is curved to provide the degree of bow required for a specific application.
- a plurality of specially designed ball bearing assemblies 14 mounted on axle 12 so that the outer races (not shown) of ball bearing assemblies 14 are free to turn, while inner races of the ball bearing assemblies (not shown) are held stationary on axle 12.
- outer shell 15, or spool as commonly referred to in the art, is affixed to the outer race of each bearing assembly 14.
- a special elastomeric sleeve 18 made out of flexible rubber is assembled over the outer shells 15 of ball bearing assemblies 14.
- Bowed roll 10 has concave side 26 and convex side 28 with an apex shown approximately by arrow 30. Although not shown, bowed roll 10 is mounted in special mounting brackets which allow the roll to be mounted at any angle to vary the location of the roll's apex 30 with respect to the traveling web under process.
- flexible sleeve 18 expands with rotation from the concave side 26 of curved axle 12 to the convex side 28.
- the bowed roll is set so the web approaches the roll on concave side 26 and leaves on convex side 28. In this way the web is spread out in the cross machine direction. Setting of the bow direction is easily accomplished by rotating axle 12 in special mounting brackets, (not shown).
- FIG. 5B is a partial cutaway of bowed roll 10 of the present invention which shows a flexible sleeve 18 covered with an adhesive layer 20 and a multiplicity of release layers 21-25 according to the present invention.
- each outer shell 15 of each individual bearing assembly 14 may have each outer shell 15 of each individual bearing assembly 14 covered with the coating of the present invention.
- FIG. 6A is a side view of a bowed roll covered with the release coating of the present invention.
- FIG. 6B and phantom lines 12 show how bowed roll 10 may be located between guide rolls, lead-in 30 and lead-out 32, respectively, to expand travelling web 34.
- the spreading of travelling web 34, (or felt) starts when the web 34 leaves lead-in roll 30 which is directly before bowed roll 10. As the web 34 leaves bowed roll 10, spreading is complete.
- lead-out roll 32 is proximally located after bowed roll 10. The closer bowed roll 10 is to the next roll in process, the better the job of "locking in” the spreading that is accomplished.
- web 34 can be spread evenly from the center to both outside edges of the roll, or spread more at the center than the edges to correct baggy centers, or more at the edges to correct slacking edges.
- the present invention is further illustrated by the following non-limiting example.
- the adhesive and release coatings are comprised of the solutions tabulated by percentage weight in TABLES 3 and 4, respectively.
- TABLE 5 lists the various chemicals of TABLE 4 with their average molecular weights and chemical structures using Lewis structures as is known in the art. Where applicable, commonly used acronyms are also listed in parenthesis.
- the solutions which comprise the adhesive and release coatings, respectively, are mixed in separate mixing vessels for 15 minutes before use and continuously thereafter, throughout the application of the coating to the machine element. Both coating materials, adhesive and release coating solutions, are held at elevated temperature, preferably on the order of about 150°F, and are continuously-mixed in their respective pressure vessels, preferably at a mixing speed of 200 rpm.
- the preferred cationic photoinitiator is Triarylsulfonium Hexaflouroantimonate and the preferred Free Radical Photoinitiator is Isobutyl Benzoin Ether.
- roll 1 is mounted rotatably in bearings 2 and 3.
- the adhesive and release coating chemical compositions of Tables 3 and 4 are contained in reservoirs 5 and 6 respectively having sprayheads 7 and 8 respectively and supported on a traversing carriage 11.
- Curing energy sources 9 and 10 are mounted on both sides of spray heads 7 and 8 to allow coating and curing in both traversing directions.
- the spray application system is composed of low pressure, pressurized liquid feed vessel and a high volume head applicator gun.
- the adhesive coating admixture (TABLE 3), is applied with a gun pressure of 50 psi from mixing vessel 5 through sprayhead 7 to form an initial substrate layer on the surface of the rotating roll with a film thickness of approximately .003".
- Both coating materials, adhesive and release coating solutions are held at elevated temperature, preferably on the order of about 150°F, and are continuously-mixed in their respective pressure vessels, 7 and 8, preferably at a mixing speed of 200 rpm.
- the rotational surface speed of roll 1 is approximately 30 feet per minute while the speed of carriage traverse 11 varies with the diameter of roll 1. In this specific example, a roll having a diameter of 7" requires the traverse speed to be 60" per minute.
- the adhesive layer application starts at end 20 of roll 1 and proceeds beyond the end 30 while following curing energy source 9 is activated to effect a partial cure of the applied coating layer.
- Each energy source 9 and 10 consists of 12" long focused ultraviolet lamps that deliver 450 watts per inch of lamp length.
- the second coating layer which is the first release layer is applied over the initial adhesive layer in the opposite direction from end 30 to end 20, using second traversing energy source 10 to partially cure that layer. Traversing from end to end, the procedure of applying additional layers of the release coating is repeated until a desired coating thickness of .060" is applied and partially cured. After applying the final layer of release coating, the carriage traverse speed is reduced to 20" per minute and both curing energy sources 9 and 10 are used to increase radiation energy per square inch of coating by a factor of six to complete the radiant energy curing of the coating. Further post cure is accomplished by moisture, and room temperature thermal curing for several days. The over spray is removed from the air through a filtered exhaust system.
- the release coating manufactured in accordance with the above has the properties indicated in TABLES 5 & 6. Release values in pounds per inch of bond line using Scotch brand No. 230 3M Drafting and Universal Brand No. 51301 Masking Tape. 3M 230 Universal 51301 UV Release Coating .08 .25 Teflon polymer Tube .11 .38 Coefficient of Friction of Kraft Paper on Coating Surface UV Release Coating .07 Teflon Polymer Tube .09
- This coating can also be applied to rolls that are installed in process machines located at end users production facilities using transportable portable application and over spray accumulating filtered exhaust systems.
- Rolls having release coatings in accordance with the present invention are advantageously employed in mills for making sized, filled and coated paper.
- a process is shown diagrammatically for coating paper including press and bowed rolls covered with the release coating of the present invention.
- web 1 from the direction indicated by arrow 2 enters size bath 3 containing viscid liquid coating 4.
- As Web 1 is completely coated it is processed under and over several carrying rolls 5a-5c respectively, and passed through nip press 6 comprised of press rolls 7a and 7b. Then web 1 is spread by bowed roll 8 and carrying roll 9 prior to the removal of moisture and curing by heated roll 10 rotating in the direction indicated by arrow 11.
- Arrow 12 and circles 13 and 14, represent bowed roll 8 and form a symbol well known in the art used to indicate bow direction.
- This conventional symbol of a double circled arrow is used throughout FIGS. 8 through 11.
- the double circled arrow symbolically indicates bow direction from side 13 to apex 14 of bowed roll 8.
- apex 14 of bowed roll 8 (or arrow 12) is rotated away from web 1, the greater the degree of spreading towards the edges of the web 1 to eliminate slacking edges.
- the release coating of the present invention is applied to the machine elements described above, the travelling web 1 does not stick to the various roll surfaces.
- FIG. 9 shows diagrammatically how feed roll 1 supplies web 2 over carrying rolls 3a and 3b in the direction shown by arrows 4a, 4b and 4c.
- Bowed roll 5a covered with the release coating of the present invention is located before size press 6 and maintains web 2 under even crosswise tension before saturation with viscid matter.
- Bowed rolls 5b and 5c are covered with the release coating of the present invention, and in conjunction with drier rolls 7a, 7b and 7c, are used to eliminate wet wrinkles and control baggy centers and slack edges.
- FIG. 9 shows diagrammatically how feed roll 1 supplies web 2 over carrying rolls 3a and 3b in the direction shown by arrows 4a, 4b and 4c.
- FIG. 10 illustrates diagrammatically how web 1 travelling in the direction indicated by arrows 2a and 2b passes over carrying roll 3, bowed roll 4 and through coating station 5 comprising press rolls 6a and 6b, and coating bath 7 which contains viscid matter 8.
- Bowed roll 4 which is covered with the release coating of the present invention, is located ahead of a coating station to eliminate wrinkles. Although not shown, bowed roll 4 can be alternatively located after the coating station.
- FIG. 11 illustrates the lamination of sheets 1 and 2 and shows how bowed rolls 3 and 4 and carrying rolls 5, 6, 7 and 8, covered with the release coating of the present invention, can be arranged to keep sheets 1 and 2 wrinkle free and under even tension thereby avoiding air bubbles in the lamination. Also shown are supply rolls 9 and 10, and press rolls 11 and 12.
- the web 1 under process does not stick to the rolls and the machine elements involved do not gum up.
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Abstract
Release coatings are provided which will bond securely to
commonly used structural and elastomeric, rigid and
flexible substrates; including metallic and non-metallic
materials. The coatings are compositions of varying
percentages of 2-phenoxyethyl acrylate, tetraethylene
glycol diacrylate, isobutyl benzoin ether, 1,6 hexanediol
diacrylate, cycloaliphatic bis A epoxide, polyurethane
acrylate, methyl methacrylate, polysiloxane and other
acrylics, tertiary amines, epoxidized novolac, fluorinated
alkyloxylate, electromagnetic wave energy sensitive
photoinitiators and electromagnetic energy absorbers.
Multiple coating layers and multiple frequencies of wave
energy are employed to cure the coatings in order to
achieve optimum adhesion to substrates combined with
optimum release, flexibility, hardness, low friction and
abrasion resistance of coatings. The usable electromagnetic
wave lengths range from long wave ultraviolet down to short
wave gamma rays (i.e. 5500 Å to 0.006 Å). Electron beam
bombardment can also be used without photoinitiators.
Description
The field of this invention is finished coatings for rolls
used in industrial applications, and more particularly, rolls
having release coatings, methods for making such coatings, and
methods for coating rolls.
The field of this invention also relates to machine elements
used to transport and process a viscid web and, a method for
transporting such a web.
Covered rolls are used industrially in demanding
environments where they are subjected to high dynamic loads and
temperatures. Covered rolls are used not only for transporting
the material under process, which is in the form of a travelling
web, but also for processing the web itself into a finished
product.
Bowed rolls are a particular kind of machine element used to
correct distortions and similar problems by distributing lateral
tension evenly across a travelling sheet material. For example,
bowed rolls are used to spread out or expand the travelling web
for the purposes of maintaining width, eliminating wrinkles,
eliminating baggy centers or slack edges. Bowed rolls are also
used to control felts by maintaining their width, openness and
seams, and to eliminate interleaving of individual slit webs on
winders.
Press rolls are yet another kind of machine element used in
nip presses. Press rolls process the travelling web by
compressing the web at the nip. Typically this is done to remove
liquids from the web, e.g., dewatering presses, or to eliminate
high and low spots in a finished product, e.g., finish nip
presses.
United States Patent No. 2,393,191 issued to John
Robertson, discloses how the transfer of sticky viscid materials
onto the roll and ultimately into the ball bearings causes rapid
gumming of the races and failure of the roll. Robertson also
discloses an expander roll having a rubber cover which allows
delicate web sheet fabrics to be processed without tearing.
Bowed rolls with elastomeric sleeves and press rolls with
compliant elastomeric covers are machine elements used in
applications where the web under process is coated with surface
enhancing materials that are tacky and subject to transfer to any
surface in contact with the web. In general, the transfer of
viscid materials from the web to the surface of the roll results
in the degradation of the roll's surface and the web's surface.
Therefore, it is desirable to have such rolls coated with a
material that is, inter alia, self-cleaning, i.e., has high
release properties. Rolls covered with release coatings prevent
excessive sticking which ultimately allows the "release" of the
viscid material from the roll surface.
Industrial web processing applications in the paper, textile
and plastics industries, are enhanced through the use of covered
rolls with surfaces that have high resistance to abrasion,
optimum release properties, flexibility and low coefficients of
friction. At present, industrial needs are met by rolls
having surfaces treated with epoxies, urethanes, Teflon polymers,
silicones or waxes. Epoxies and urethanes have desirable
abrasion resistance properties, but lack the desired high
release properties and low coefficients of friction. Teflon
polymers and silicones have high release properties and low
coefficients of friction, but lack high abrasion resistance
qualities. Waxes and silicone polish coatings do not last very
long.
The flexing surfaces of bowed rolls and press rolls must
have good coating release properties, low coefficients of
friction, high flexibility, and good abrasion resistance. The
materials that are presently being used to cover these machine
elements are Teflon shrink tubing, sintered Teflon polymer
coatings and silicones. These coatings are expensive, subject
to excessive wear rates, and exhibit poor adhesion to
substrates. Often, they are rendered useless by minor cut
damage from the mechanical removal of the web coating material
which adheres to the Teflon polymer, and must be removed
manually. Thus, the need exists to develop rolls with coatings
that are harder, have lower coefficients of friction and
improved release properties, with lower wear rates than present
day covered rolls.
The problems caused by prior art coatings, are reduced in
accordance with the present invention through the application of
a release coating to the surface of a roll or machine element.
The coating of the present invention is harder, and has a lower
coefficient of friction, better release properties and wear
rates than those of Teflon polymers.
In accordance with this invention, it has been found that a
liquid solution of varying percentages of 2-Phenoxyethyl
Acrylate, Tetraethylene Glycol Diacrylate, Isobutyl Benzoin
Ether, 1,6 Hexanediol Diacrylate, Cycloaliphatic Bis A Epoxide,
Polyurethane Acrylate, Methyl Methacrylate, Polysiloxane and
other Acrylics, Tertiary Amines, Epoxidized Novolac, Fluorinated
Alkyloxylate, Electromagnetic Wave Energy sensitive
Photoinitiators, and Electromagnetic Energy absorbers, composed
of 8% to 24% by weight of polysiloxane will produce a liquid
phase reaction of the polysiloxane and acrylated epoxy creating
a suspended precipitate of Epoxidized polysiloxane in a
predominantly Polyurethane acrylate and monomer solution.
It is an object of the present invention to provide a
coating that can be applied to metallic or nonmetallic surfaces.
Another object of this invention is to provide a method of
coating a machine element with a release coating.
Another object of this invention is to provide a method of
curing the coated surface of a machine element with
Electromagnetic Wave Energy.
Another object of this invention is to provide a method of
curing the coated surface of a machine element with Electron Beam
Bombardment.
Another object of this invention is to provide a method of
curing the coated surface of a machine element with Ultraviolet
Light Radiation.
Another object of the present invention is to provide a
coating for a machine element that is hard enough to be abrasion
resistant while having high release properties.
Another object of the present invention is to provide a
coating for a machine element that is abrasion resistant while,
having a low coefficient of friction.
Another object of the present invention is to provide a
coating for a machine element that has improved release
properties.
Another object of the present invention is to provide a
coating for a machine element that has lower wear rates than
prior art coatings.
Another object of the present invention is to provide a
coating for a machine element that has wear rates that are lower
than that of a Teflon polymer.
Another object of the present invention is to provide a
coating for a machine element that is abrasion resistant.
Another object of the present invention is to provide a
coating for a machine element that is abrasion resistant yet
complaint enough to be applied to machine elements requiring
flexible surfaces.
Another object of the present invention is to manufacture
covered machine elements having release coatings applied as a
liquid composition of 100% solids and/or solvent thinned solids.
Another object of the present invention is to apply a
release coating to machine elements located on site, i.e., at the
user's facility.
Another object of the present invention is to provide a new
and improved roll having better release properties.
Another object of the present invention is to provide an
improved method of processing a viscid web using rolls with
improved release properties.
Another object of the present invention is a method of
applying a release coating utilizing a minimum of solvents.
FIG. 1 is a perspective view illustrating the application
of the adhesive coating to a machine element in accordance with
the present invention.
FIG. 2 is a perspective view illustrating the step of
curing of a final release layer on a machine element to form a
release coating in accordance with the present invention.
FIG. 3 is a sectional view illustrating a machine element
covered with the release coating in accordance with the present
invention having a multiplicity of release layers applied over an
adhesive substrate layer.
FIG. 4A is a sectional view illustrating a nip press having
a lower cylindrical roll covered with the release coating of the
press invention.
FIG. 4B is an expanded sectional view of the encircled area
in FIG. 4A illustrating how the flexible release coating of the
present invention can withstand a nip deformation.
FIG. 5A is a plan view of a bowed roll illustrating an
elastomeric roll cover coated with a release coating in
accordance with the present invention.
FIG. 5B is partially sectioned view of a bowed roll
illustrating the adhesive and multiple release layers in
accordance with the release coating of the present invention.
FIG. 6A is a side view illustrating a bowed roll covered
with the release coating in accordance with the present
invention.
FIG. 6B is a diagram illustrating the placement of bowed
rolls in processing a viscid web in accordance with the present
invention.
FIG. 7 is a perspective view illustrating the application
of a release coating to a machine element in accordance with the
specific example of the present invention.
FIG. 8 is a diagram illustrating how a bowed roll located in
spaced relationship with press rolls and a size bath are used to
coat paper in the paper making industry.
FIG. 9 is a diagram illustrating a system of machine
elements used to transport a viscid web in the paper making
industry.
FIG. 10 is a diagram illustrating a coating process in the
paper making industry.
FIG. 11 is a diagram illustrating a system of machine
elements used to transport and laminate two viscid webs in a
paper making laminating process.
At the outset, a roll having a release coating, the
associated method for making the coating and applying it to the
roll, and a method for transporting a viscid web, are described
in their broadest overall aspects with a more detailed
description following.
In its broadest overall aspects, the release coating of the
present invention is a composite coating, comprising multiple
layers of release coating applied over an initial adhesive layer.
In manufacturing the initial adhesive layer of the present
invention, a liquid composition of 100% solids and/or solvent
thinned solids is prepared from what is essentially acrylated
epoxy, acrylated urethane and acrylated monomer. Then the
adhesive mix is applied to form an initial layer on the machine
element utilizing conventional methods, such as a sprayer.
In its broadest overall aspects, the release coating of the
present invention comprises the addition of acrylated
polysiloxane to the adhesive mix which produces a liquid phase
reaction of the acrylated polysiloxane and acrylated epoxy,
thereby creating a suspended precipitate of epoxidized
polysiloxane in a predominantly polyurethane acrylate and
acrylated monomer solution. Thus, the release coating is a
liquid composition of 100% solids and/or solvent thinned solids
prepared to form a pre-reacted solution that is essentially an
epoxidized-siloxane matrix in acrylated urethane and acrylated
monomer. Then the pre-reacted solution is applied over the
adhesive layer on the machine element utilizing conventional
methods, such as a sprayer.
The release coating, including the initial adhesive coating,
of the present invention can be applied to machine elements
located at end-users' facilities, thus reducing manufacturing
costs and facilitating emergency repairs. The adhesive and
release layers can either be prepared concurrently in separate
mixing vats or consecutively by adding the acrylated polysiloxane
subsequent to the application of the initial adhesive layer.
The adhesive and pre-reacted release coatings can be applied
to flexible or rigid substrates, such as, bowed rolls, press
rolls or carrying rolls. Through the addition of photoinitiators,
both the adhesive and release coatings can be cured using
Electromagnetic Wave Energy in the wave lengths ranging from
about 5500 Å. through 006 Å, i.e., long wave ultraviolet down to
short wave gamma rays. Alternatively, Electron Beam Bombardment
can be used to cure the coatings without the use of
photoinitiators.
TABLES 1 and 2 summarize the chemical ingredients used to
create the liquid oligomers for the adhesive and release coating
layers, respectively. As used throughout this specification and
the claims, all percentages are by weight unless otherwise
specified.
The chemicals listed in TABLE 1 are mixed together to make
the solution for the initial adhesive coat in the proportions as
indicated. Each of the ingredients can be varied as indicated
by the range of percentage amounts in TABLES 1 and 2. However,
any increase of one ingredient must be compensated by a
corresponding decrease in other components.
Adhesive Coating Chemical Composition By Weight Percentage | |
Ingredient | Range |
Acrylated Monomer | 35.6-59.4 |
Acrylated Polyurethane | 14-39 |
Acrylated Epoxy | 11-27 |
Free Radical Photoinitiator | 2-6 |
Release Coating Chemical Composition By Weight Percentage | |
Ingredient | Range |
Acrylated monomer | 28-52 |
Acrylated polyurethane | 10-35 |
Acrylated epoxy | 9-26 |
Polysiloxane | 8-24 |
Cationic Photoinitiator | 1-3 |
Free Radical Photoinitiator | 1-5 |
Generally, 2 Phenoxyethyl Acrylate and Tetraethylene Glycol
Diacrylate and 1,6 Hexanediol Diacrylate are polyacrylates that
comprise the acrylated monomer. Cycloaliphatic Bis A epoxy
diacrylate is an example of a commonly used acrylated epoxy.
Typically, Urethane Diacrylate is combined with 1,6 Hexanediol
Diacrylate to lower viscosity in the acrylated polyurethane.
Isobutyl Benzoin Ether is an example of a commonly used free
radical initiator, while a Triarylsulfonium Hexaflouroantimonate
salt is commonly used as a cationic photoinitiator.
Other equivalent ingredients can be used to augment or
substitute the ingredients listed TABLES 1 and 2. Epoxidized
Novolac is an alternative epoxy which imparts further abrasion
resistance and hardness to the final product, if so desired, as
for example in a press roll. Tertiary amines are additive
adjuncts to photoinitiators which extend the curing beyond the
Ultraviolet Cure Phase. A Methacrylate, such as
Glycidylmethacrylate, for example, can be used as an alternative
highly reactive monomer, and when added, Flourinated Alkyloxylate
Imparts additional release properties to the coatings.
In general, to manufacture a coated machine element of the
present invention, 9 to 26 by percentage weight acrylated epoxy,
10 to 35 by percentage weight acrylated urethane, 8 to 24 by
weight acrylated polysiloxane, 28 to 52 by percentage weight
acrylated monomer, and 2 to 8 by percentage weight of cationic
and free radical photoinitiators are initially mixed together to
form a mixture of liquid oligomers in a mixing vat.
In its broadest overall terms, the release coating of the
present invention comprises oligomers of acrylated epoxy,
acrylated urethane, acrylated siloxane and acrylated monomer.
Ultimately, it is the acrylated epoxy and acrylated urethane
components which provide abrasion resistance properties to the
coating while the acrylated urethane and acrylated monomer
components add compliance and flexibility. The epoxidized
siloxane precipitate further imparts hardness and high release
properties to the coating.
Photoinitiators are added to the oligomers to cross-link the
pre-reacted solution upon the application of Electromagnetic
Energy. Electromagnetic Radiation of a machine element covered
with the release coating of the present invention, causes the
photoinitiators to generate free radicals and cationic particles
which initiate the formation of cross-linking bonds among the
polymers and the siloxane. Several different kinds and
combinations of photoinitiators can be used as described in the
text, "Radiation Curing Science and Technology," Edited by S.
Peter Papas, (1992 Plenum Press), the teachings of which are
hereby incorporated by reference.
FIG.1 illustrates how the adhesive coating of the present
invention is applied to a roll 10 mounted rotatably in bearings
11 and 12. Arrow 13 indicates the direction of roll 10, which is
arbitrary. A traverse carriage 1 travels back and forth
alongside roll 10. For purposes of illustration, traverse
carriage 1 is shown moving in the direction of arrow 2. Mixing
vessel 3 which contains the oligomers comprising the adhesive
coating, and ultraviolet lamps 6 are mounted on top of traverse
carriage 1. Sprayhead 4 applies liquid adhesive coating 5 to coat
roll 10 to form a first layer 14 for subsequent bonding of
additional release coating layers thereto. Ultra-violet lamps 6
radiate long wave-length Electromagnetic Energy 7 to effect a
partial cure of the adhesive layer 14. This creates good
adhesion between the initial adhesive layer 14 and roll 10, and
provides a partially reacted reactive film 15 on the outer
surface for subsequent bonding with additional layers of release
coating.
The pre-reacted liquid oligomer mixture comprising the
release coating is applied in the same manner as with the
adhesive coating. Similar to FIG. 1, FIG. 2 shows how a roll 10
of the present invention is finally cured with ultraviolet lamps
5 which radiate Electromagnetic Wave Energy 6. Arrow 13
indicates the rotational direction of roll 10, which is
arbitrary. FIG. 2 further shows symbolically how final layer 16
is cured to form a finished release coating 17 which is a matrix
composed of hard sites of cross-linked Epoxidized Polysiloxane
Acrylate dispersed in a flexible lower modulus binder of cross-linked
polyurethane acrylate and acrylated monomer.
Electromagnetic Wave Energy transparent reinforcing fillers
(not shown) may be used to increase individual coating film
thickness and reduce production costs.
FIG. 3 shows one embodiment of the present invention is a
cylindrical machine element covered with multilayers of release
coating. Metal roll 10 is coated with an initial adhesive
layer 11 that has been partially cured. This is followed by the
application of multiple layers of release coating containing
polysiloxane, layers 12 through 16, until a flexible, abrasion-resistant
release layer of desired thickness is formed.
With respect to FIGS. 1-3, the final coating comprised of
all layers is cured with more intense and shorter wave length
energy. Throughout the application process, multiple coating
layers and multiple frequencies of wave energy are employed to
cure the coatings in order to achieve optimum adhesion to
substrates combined with optimum release, flexibility, hardness,
low friction, and abrasion resistance of coatings.
The degree of flexibility or rigidity of the cured coating
can be controlled by the percentages of acrylated epoxy and
acrylated urethane used in the solutions. The reacted liquid
phase of the coating contains 1-4% of a combination of free
radical and cationic particle generating photo-initiators which
react with electromagnetic wave energy (e.g., ultraviolet light)
to effect a hard cure of the liquid coating.
With further reference to FIGS. 1-3, the initial adhesive
coat 11 is composed of acrylated polyurethane, acrylated epoxy
and acrylated monomers. The subsequent additional multiple
layers, layers 12-16, contain the epoxidized polysiloxane
precipitate matrix suspended in polyurethane acrylate and
acrylated monomer. This combination provides extremely good
adhesion to substrates combined with a thick multi-layered
coating with good hardness, and release properties throughout
the depth of the coating, instead of the poorly adhered silicone
rich surface which results from small additions of polysiloxane,
0.5-2% by weight for example, and which does not last long in a
web processing application.
FIGS. 4A and 4B show a nip press 10 having upper and lower
cylindrical machine elements 1 and 2 respectively. The lower
machine element 2 is coated with a flexible release coating 4 of
the present invention. (For illustrative purposes, the
travelling web or sheet under process is not shown.) FIG. 4B,
which is an enlargement of encircled area 3 in FIG. 4A, shows
lower machine element 2 coated with the release coating of the
present invention comprising initial adhesive layer 11 and
multiple layers of release coating 16 which have been applied as
described above. FIG. 4B also shows how the release coating of
the present invention must have enough flexibility to withstand a
nip deformation 20.
FIG. 5A shows generally how a bowed roll 10 consists of
three basic elements. A non-rotating axle 12 that is curved to
provide the degree of bow required for a specific application. A
plurality of specially designed ball bearing assemblies 14
mounted on axle 12 so that the outer races (not shown) of ball
bearing assemblies 14 are free to turn, while inner races of the
ball bearing assemblies (not shown) are held stationary on axle
12. With further reference to FIG 5A, outer shell 15, or spool
as commonly referred to in the art, is affixed to the outer race
of each bearing assembly 14. A special elastomeric sleeve 18
made out of flexible rubber is assembled over the outer shells 15
of ball bearing assemblies 14. Bowed roll 10 has concave side 26
and convex side 28 with an apex shown approximately by arrow 30.
Although not shown, bowed roll 10 is mounted in special mounting
brackets which allow the roll to be mounted at any angle to vary
the location of the roll's apex 30 with respect to the traveling
web under process.
In operation, flexible sleeve 18 expands with rotation from
the concave side 26 of curved axle 12 to the convex side 28. The
bowed roll is set so the web approaches the roll on concave side
26 and leaves on convex side 28. In this way the web is spread
out in the cross machine direction. Setting of the bow direction
is easily accomplished by rotating axle 12 in special mounting
brackets, (not shown).
FIG. 5B is a partial cutaway of bowed roll 10 of the present
invention which shows a flexible sleeve 18 covered with an
adhesive layer 20 and a multiplicity of release layers 21-25
according to the present invention.
Although not shown, bowed rolls without elastomeric sleeves
may have each outer shell 15 of each individual bearing assembly
14 covered with the coating of the present invention.
FIG. 6A is a side view of a bowed roll covered with the
release coating of the present invention. FIG. 6B and phantom
lines 12 show how bowed roll 10 may be located between guide
rolls, lead-in 30 and lead-out 32, respectively, to expand
travelling web 34. The spreading of travelling web 34, (or
felt), starts when the web 34 leaves lead-in roll 30 which is
directly before bowed roll 10. As the web 34 leaves bowed roll
10, spreading is complete. To prevent the web's tendency of
reverting back to its original state, lead-out roll 32 is
proximally located after bowed roll 10. The closer bowed roll
10 is to the next roll in process, the better the job of "locking
in" the spreading that is accomplished. Also by varying the
configuration of bowed roll 10, web 34 can be spread evenly
from the center to both outside edges of the roll, or spread more
at the center than the edges to correct baggy centers, or more at
the edges to correct slacking edges.
The present invention is further illustrated by the
following non-limiting example.
In this specific example, the adhesive and release coatings,
are comprised of the solutions tabulated by percentage weight in
TABLES 3 and 4, respectively. As a corollary to TABLE 4 and as
used throughout this specification and claims, TABLE 5 lists the
various chemicals of TABLE 4 with their average molecular weights
and chemical structures using Lewis structures as is known in the
art. Where applicable, commonly used acronyms are also listed in
parenthesis.
(SPECIFIC EXAMPLE) Adhesive Coating Chemical Composition By Weight | |
Ingredient | % |
2 Phenoxyethyl Acrylate | 44 |
Tetraethylene Glycol Diacrylate | 4.4 |
1,6 | 20 |
Cycloaliphatic Bis A | 20 |
| 6 |
Isobutyl Benzoin Ether | 5.6 |
(SPECIFIC EXAMPLE) Release Coating Chemical Composition By Weight | |
Ingredient | % |
2 Phenoxyethyl Acrylate | 36 |
| 3 |
1,6 | 16 |
Cycloaliphatic Bis A | 16 |
| 5 |
Polysiloxane (Poly)Methoxy(Meth) | 16 |
| 3 |
| 5 |
The solutions which comprise the adhesive and release
coatings, respectively, are mixed in separate mixing vessels
for 15 minutes before use and continuously thereafter, throughout
the application of the coating to the machine element. Both
coating materials, adhesive and release coating solutions, are
held at elevated temperature, preferably on the order of about
150°F, and are continuously-mixed in their respective pressure
vessels, preferably at a mixing speed of 200 rpm. The
preferred cationic photoinitiator is Triarylsulfonium
Hexaflouroantimonate and the preferred Free Radical
Photoinitiator is Isobutyl Benzoin Ether.
With reference to FIG. 7, roll 1 is mounted rotatably in
bearings 2 and 3. The adhesive and release coating chemical
compositions of Tables 3 and 4 are contained in reservoirs 5 and
6 respectively having sprayheads 7 and 8 respectively and
supported on a traversing carriage 11. Curing energy sources 9
and 10 are mounted on both sides of spray heads 7 and 8 to allow
coating and curing in both traversing directions. The spray
application system is composed of low pressure, pressurized
liquid feed vessel and a high volume head applicator gun.
In this specific example and with further reference to FIG.
7, the adhesive coating admixture, (TABLE 3), is applied with a
gun pressure of 50 psi from mixing vessel 5 through sprayhead 7
to form an initial substrate layer on the surface of the
rotating roll with a film thickness of approximately .003".
Both coating materials, adhesive and release coating solutions,
are held at elevated temperature, preferably on the order of
about 150°F, and are continuously-mixed in their respective
pressure vessels, 7 and 8, preferably at a mixing speed of 200
rpm. As indicated by arrow 15, the rotational surface speed of
roll 1 is approximately 30 feet per minute while the speed of
carriage traverse 11 varies with the diameter of roll 1. In this
specific example, a roll having a diameter of 7" requires the
traverse speed to be 60" per minute. The adhesive layer
application starts at end 20 of roll 1 and proceeds beyond the
end 30 while following curing energy source 9 is activated to
effect a partial cure of the applied coating layer. Each energy
source 9 and 10 consists of 12" long focused ultraviolet lamps
that deliver 450 watts per inch of lamp length.
Then the second coating layer which is the first release
layer is applied over the initial adhesive layer in the
opposite direction from end 30 to end 20, using second
traversing energy source 10 to partially cure that layer.
Traversing from end to end, the procedure of applying additional
layers of the release coating is repeated until a desired coating
thickness of .060" is applied and partially cured. After
applying the final layer of release coating, the carriage
traverse speed is reduced to 20" per minute and both curing
energy sources 9 and 10 are used to increase radiation energy per
square inch of coating by a factor of six to complete the radiant
energy curing of the coating. Further post cure is accomplished
by moisture, and room temperature thermal curing for several
days. The over spray is removed from the air through a filtered
exhaust system.
The release coating manufactured in accordance with the
above has the properties indicated in TABLES 5 & 6.
Release values in pounds per inch of bond line using Scotch brand No. 230 3M Drafting and Universal Brand No. 51301 Masking Tape. | ||
3M 230 | Universal 51301 | |
UV Release Coating | .08 | .25 |
Teflon polymer Tube | .11 | .38 |
Coefficient of Friction of Kraft Paper on Coating Surface | |
UV Release Coating | .07 |
Teflon Polymer Tube | .09 |
This coating can also be applied to rolls that are installed
in process machines located at end users production facilities
using transportable portable application and over spray
accumulating filtered exhaust systems.
Rolls having release coatings in accordance with the present
invention are advantageously employed in mills for making sized,
filled and coated paper. Referring to FIG. 8, a process is shown
diagrammatically for coating paper including press and bowed rolls
covered with the release coating of the present invention. As
shown in FIG 8, web 1 from the direction indicated by arrow 2
enters size bath 3 containing viscid liquid coating 4. As Web 1
is completely coated it is processed under and over several
carrying rolls 5a-5c respectively, and passed through nip press 6
comprised of press rolls 7a and 7b. Then web 1 is spread by
bowed roll 8 and carrying roll 9 prior to the removal of moisture
and curing by heated roll 10 rotating in the direction indicated
by arrow 11. Arrow 12 and circles 13 and 14, represent bowed
roll 8 and form a symbol well known in the art used to indicate
bow direction. This conventional symbol of a double circled arrow
is used throughout FIGS. 8 through 11. With specific reference to
FIG. 8, the double circled arrow symbolically indicates bow
direction from side 13 to apex 14 of bowed roll 8. As known in
the art, the higher the apex 14 with respect to side 13,
indicated by arrow 12 being rotated into web 1, the greater the
amount of spreading to eliminate baggy centers. Conversely, as
apex 14 of bowed roll 8, (or arrow 12), is rotated away from web
1, the greater the degree of spreading towards the edges of the
web 1 to eliminate slacking edges. When the release coating of
the present invention is applied to the machine elements described
above, the travelling web 1 does not stick to the various roll
surfaces.
FIG. 9 shows diagrammatically how feed roll 1 supplies web 2
over carrying rolls 3a and 3b in the direction shown by arrows 4a,
4b and 4c. Bowed roll 5a covered with the release coating of the
present invention, is located before size press 6 and maintains
web 2 under even crosswise tension before saturation with viscid
matter. Bowed rolls 5b and 5c are covered with the release
coating of the present invention, and in conjunction with drier
rolls 7a, 7b and 7c, are used to eliminate wet wrinkles and
control baggy centers and slack edges. FIG. 10 illustrates
diagrammatically how web 1 travelling in the direction indicated
by arrows 2a and 2b passes over carrying roll 3, bowed roll 4 and
through coating station 5 comprising press rolls 6a and 6b, and
coating bath 7 which contains viscid matter 8. Bowed roll 4 which
is covered with the release coating of the present invention, is
located ahead of a coating station to eliminate wrinkles.
Although not shown, bowed roll 4 can be alternatively located
after the coating station. FIG. 11 illustrates the lamination of
sheets 1 and 2 and shows how bowed rolls 3 and 4 and carrying
rolls 5, 6, 7 and 8, covered with the release coating of the
present invention, can be arranged to keep sheets 1 and 2 wrinkle
free and under even tension thereby avoiding air bubbles in the
lamination. Also shown are supply rolls 9 and 10, and press rolls
11 and 12.
In accordance with the present invention, the web 1 under
process does not stick to the rolls and the machine elements
involved do not gum up.
In the foregoing specification, the invention has been
described with reference to specific exemplary embodiments
thereof. It will, however, be evident that various modifications
and changes may be made thereunto without departing from the
spirit and scope of the invention as set forth in the appended
claims. The drawings and specification are, accordingly, to be
regarded in an illustrative rather than in a restrictive sense.
Claims (20)
- A method of applying a release coating to the surface of a machine element, said method comprising the steps of:a) applying a first oligomer mixture onto said surface to form an adhesive layer;b) radiating said adhesive layer with enough electromagnetic energy to effect a partial cure of said layer;c) applying a second pre-reacted reactive oligomer mixture onto said adhesive layer to form a first release layer, said first release layer bonding with said adhesive layer, and curing said release layer with a sufficient amount of electromagnetic energy;d) finally radiating said layers with enough electromagnetic energy to form a fully cured homogenous coating.
- The method of Claim 1, further including the step of repeating step (c) until enough release layers are applied to form a coating of a desired thickness.
- The method of Claim 1 or 2, wherein forming said first oligomer mixture comprises the steps of mixing liquid solutions of varying percentages by weight of acrylated epoxy, acrylated urethane and acrylated monomer and continuously mixing said mixture at an elevated temperature.
- The method of Claim 3, wherein said temperature is about 150°F.
- The method of Claim 1, wherein forming said second pre-reacted reactive oligomer mixture comprises the steps of mixing liquid solutions of varying percentages by weight of acrylated epoxy, acrylated urethane, acrylated monomer and polysiloxane at an elevated temperature, said second pre-reacted reactive oligomer mixture being in a liquid state that is continuously stirred in a mixing vessel.
- The method of Claim 5, wherein said temperature is about 150°F.
- The method of any one of the Claims 1 to 6, wherein said oligomer mixture further comprises photoinitiators.
- The method of any one of the Claims 1 to 7, wherein said release coating is cured with electron beam bombardment.
- The method of any one of the Claims 1 to 8, wherein the step of applying said release coating is performed on a machine element being located on-site at a user's facility.
- A method of applying a release coating to the surface of a roll comprising the steps of mixing a liquid solution of varying percentages of 2-phenoxyethyl acrylate, tetraethylene glycol diacrylate, isobutyl benzoin ether, 1,6 hexanediol diacrylate, cycloaliphatic bis A epoxy diacrylate, polyurethane acrylate, 1,6 hexanediol diacrylate, methyl methacrylate, methoxy(meth)acrylate siloxane and other acrylics, tertiary amines, epoxidized novolac, fluorinated alkyloxylate, electromagnetic wave energy sensitive photoinitiators, and electromagnetic energy absorbers, composed of 5% to 30% by weight of polysiloxane, said liquid mix producing a liquid phase reaction of the polysiloxane and acrylated epoxy thereby creating a suspended precipitate of epoxidized polysiloxane in a predominantly acrylated polyurethane and monomer solution.
- The method of Claim 10, further including the step of applying said release coating to a roll, said roll being located on-site at a user's facility.
- A roll having a bowed stationary axle supporting a multiplicity of rotatable bearings with rigid cylindrical shells fixed to and encompassing the rotating outer race of the bearings which support a continuous flexible elastomeric sleeve rotationally about the stationary bowed axle, said roll comprising:an abrasion resistant, flexible, release coating, said coating being applied to said flexible elastomeric sleeve and cured with electromagnetic wave energy, said release coating further comprising cross-linked epoxidized polysiloxane acrylate dispersed in a flexible lower modulus binder of cross-linked acrylated polyurethane and acrylated monomer.
- The roll of Claim 12, wherein said release coating is cured with electron beam bombardment or electromagnetic wave energy, in particular electromagnetic wave energy with a wave-length in the range of 5500 Å to 6 Å.
- A roll having a bowed stationary axle supporting a multiplicity of rotatable bearings with rigid cylindrical shells fixed to an encompassing the rotating outer race of the bearings, said roll comprising:an abrasion resistant, flexible, release coating, said coating being applied to said cylindrical shells and cured with electromagnetic wave energy, said release coating further comprising cross-linked epoxidized polysiloxane acrylate dispersed in a flexible lower modulus binder of cross-linked acrylated polyurethane and acrylated monomer.
- The roll of Claim 14, wherein said release coating is cured with electron beam bombardment or electromagnetic wave energy, in particular electromagnetic wave energy with a wave-length in the range of 5500 Å to 6 Å.
- A flexible press roll having surfaces with a rigid cylindrical shell surrounded by a thick low modulus elastomeric cover which is indented in the pressure nip zone produced by a second roller, said roll comprising a flexible release coating which is cured in place with electromagnetic wave energy, said release coating further comprising cross-linked epoxidized polysiloxane acrylate dispersed in a flexible lower modulus binder of cross-linked acrylated polyurethane and acrylated monomer.
- The roll of Claim 13, wherein said flexible release coating is cured with electron beam bombardment or electromagnetic wave energy, in particular electromagnetic wave energy with a wave-length in the range of 5500 Å to 6 Å.
- A carrying roll having a cylindrical surface, said roll comprising a flexible release coating which is cured in place with electromagnetic wave energy, said release coating further comprising cross-linked epoxidized polysiloxane acrylate dispersed in a flexible lower modulus binder of cross-linked acrylated polyurethane and acrylated monomer.
- The roll of Claim 16, wherein said flexible release coating is cured with electron beam bombardment or electromagnetic wave energy, in particular electromagnetic wave energy with a wave-length in the range of 5500 Å to 6 Å.
- A process for processing a viscid material comprising the step of passing said material over machine elements covered with a release coating, said release coating further comprising cross-linked epoxidized polysiloxane acrylate dispersed in a flexible lower modulus binder of cross-linked acrylated polyurethane and acrylated monomer.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002187055A CA2187055A1 (en) | 1995-10-04 | 1996-10-03 | Rolls having release coatings, a method for applying a release coating to a roll, and a method of transporting a viscid web |
EP96117020A EP0838269A1 (en) | 1995-10-04 | 1996-10-23 | Rolls having release coatings, a method for applying a release coating to a roll, and a method of transporting a viscid web |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US53920095A | 1995-10-04 | 1995-10-04 | |
EP96117020A EP0838269A1 (en) | 1995-10-04 | 1996-10-23 | Rolls having release coatings, a method for applying a release coating to a roll, and a method of transporting a viscid web |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0838269A1 true EP0838269A1 (en) | 1998-04-29 |
Family
ID=26142255
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP96117020A Withdrawn EP0838269A1 (en) | 1995-10-04 | 1996-10-23 | Rolls having release coatings, a method for applying a release coating to a roll, and a method of transporting a viscid web |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0838269A1 (en) |
CA (1) | CA2187055A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2353739A (en) * | 1999-09-04 | 2001-03-07 | Federal Mogul Technology Ltd | Applying a low friction and low wear coating |
WO2002094457A2 (en) * | 2001-05-18 | 2002-11-28 | Klebchemie M.G. Becker Gmbh & Co. Kg | Method and device for producing parts having a sealing layer on the surface, and corresponding parts |
US7997314B2 (en) | 2001-05-18 | 2011-08-16 | Klebchemie M.G. Becker Gmbh & Co. Kg | Method and device for producing veneer and veneered parts and veneer and veneered parts |
WO2016057316A1 (en) * | 2014-10-05 | 2016-04-14 | Traktec, Llc | Method and apparatus producing electron beam cured direct thermal paper |
CN114632681A (en) * | 2022-03-31 | 2022-06-17 | 广东莱尔新材料科技股份有限公司 | UV curing conveying roller for wafer protective film and preparation method thereof |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2393191A (en) * | 1945-02-21 | 1946-01-15 | John D Robertson | Expander roll |
JPH0584869A (en) * | 1991-09-27 | 1993-04-06 | Nitto Denko Corp | Fluoroplastic silicone rubber laminated and production thereof |
JPH05271609A (en) * | 1992-03-24 | 1993-10-19 | Toray Ind Inc | Coating resin composition |
GB2281232A (en) * | 1993-08-27 | 1995-03-01 | Coyle John E | A process for polishing a panel |
DE4421558A1 (en) * | 1994-06-20 | 1995-12-21 | Osmetric Entwicklungs Und Prod | Metal substrate coating system |
-
1996
- 1996-10-03 CA CA002187055A patent/CA2187055A1/en not_active Abandoned
- 1996-10-23 EP EP96117020A patent/EP0838269A1/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2393191A (en) * | 1945-02-21 | 1946-01-15 | John D Robertson | Expander roll |
JPH0584869A (en) * | 1991-09-27 | 1993-04-06 | Nitto Denko Corp | Fluoroplastic silicone rubber laminated and production thereof |
JPH05271609A (en) * | 1992-03-24 | 1993-10-19 | Toray Ind Inc | Coating resin composition |
GB2281232A (en) * | 1993-08-27 | 1995-03-01 | Coyle John E | A process for polishing a panel |
DE4421558A1 (en) * | 1994-06-20 | 1995-12-21 | Osmetric Entwicklungs Und Prod | Metal substrate coating system |
Non-Patent Citations (2)
Title |
---|
DATABASE WPI Section Ch Week 9318, Derwent World Patents Index; Class A14, AN 93-148830, XP002053733 * |
DATABASE WPI Section Ch Week 9346, Derwent World Patents Index; Class A14, AN 93-365464, XP002053734 * |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2353739A (en) * | 1999-09-04 | 2001-03-07 | Federal Mogul Technology Ltd | Applying a low friction and low wear coating |
WO2002094457A2 (en) * | 2001-05-18 | 2002-11-28 | Klebchemie M.G. Becker Gmbh & Co. Kg | Method and device for producing parts having a sealing layer on the surface, and corresponding parts |
WO2002094457A3 (en) * | 2001-05-18 | 2004-03-11 | Klebchemie M G Becker Gmbh | Method and device for producing parts having a sealing layer on the surface, and corresponding parts |
US7939137B2 (en) | 2001-05-18 | 2011-05-10 | Klebchemie M.G. Becker Gmbh & Co. Kg | Method and device for producing parts having a sealing layer on the surface, and corresponding parts |
US7997314B2 (en) | 2001-05-18 | 2011-08-16 | Klebchemie M.G. Becker Gmbh & Co. Kg | Method and device for producing veneer and veneered parts and veneer and veneered parts |
WO2016057316A1 (en) * | 2014-10-05 | 2016-04-14 | Traktec, Llc | Method and apparatus producing electron beam cured direct thermal paper |
CN114632681A (en) * | 2022-03-31 | 2022-06-17 | 广东莱尔新材料科技股份有限公司 | UV curing conveying roller for wafer protective film and preparation method thereof |
Also Published As
Publication number | Publication date |
---|---|
CA2187055A1 (en) | 1997-04-05 |
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