FI111175B - A method of sealing a seam in a polymeric resin coated papermaking belt and a papermaking belt - Google Patents

Abstract

A loop-and-pintle seam in a paper-processing belt (72) having a polymeric-resin coating (68) is closed by covering the seam on the uncoated side with an encapsulating material, so that the seam area (50) has compression properties substantially identical to those of the remainder of the belt. After installing the belt (72) and closing the pin seam with a pintle (76), the seam region (50) is impregnated on the non-paper side with a viscous paste comprising a polymeric-resin material and a blowing agent. The paste is heated to create a foam that fills the voids in the seam region (50) and the slit (78) in the coating (68), before being cured. Alternatively, a solid foam strip (88) of a polymeric resin may be glued to the seam region (50). The belt may be used as a transfer or long-nip-press (LNP) belt. <MATH>

Description

111175

METHOD. TO CLOSE THE SEAM IN A POLYMER RESORT COATED WITH PAPER PROCESSING BELT AND PAPER PROCESSING BELT

The invention relates to a method as defined in the preamble of claim 1. The invention further relates to a papermaking belt as defined in the preamble of claim 41.

The present invention relates to a papermaking belt used to carry a paper web between the compartments of the paper machine in which it is made, or between compartments such as individual presses in the compression compartment or to convey the web for other treatments. In particular, the present invention relates to a transfer belt that can be joined to one endless shape on a paper machine during installation by a seam, and methods for closing the seam region after the seam-joined transfer belt is bonded in this manner.

Today, the only commercially available paper converting belt of this type is a transfer belt. The transfer belt is intended to both pass the paper web through a portion of the paper machine so as to avoid openings from the machine, and to easily release the web to another web or web at any desired position. By definition, open passage is one in which the web without support passes from one part of the paper machine to another over a distance greater than the length of the cellulosic fibers in the web and is susceptible to breakage. Removing open openings eliminates access to the unplanned shutdowns of 30 machines, the track breaking at a point where it is temporarily without support from a blanket or other track-carrying member. If the pulp flow is disturbed, there is a very high probability that fractures will occur at a point where the unsupported web is moved from one location to another in the press section or from the last press of the press section 2 111175 to the drying section. At such locations, the web is usually made up of at least 50% water and is therefore weak and easily breakable. Thus, the presence of an open outlet clearly sets limits on the maximum speed at which the paper machine can be operated.

A successful web transfer belt must perform three critical functions on a papermaking machine: a) Removing the paper web from the press fabric without causing web strain problems; (b) cooperate with the press fabric in one or more press nipples to ensure optimum drainage and a good quality web; and c) conveying the paper web from a single press in a press section to a web receiving web or belt in a subsequent press or presses in a press section or to a drying-picking fabric in a drying section.

Successfully accomplishing these three critical functions, the web transfer belt is disclosed in U.S. Patent No. 5,298,124, issued March 29, 1994, entitled "Transfer Belt," which is incorporated herein by reference. The transfer belt disclosed in the patent has a surface topography which is characterized by having a pressure-sensitive, reversible degree of grit so that when the compression in the nip decreases the degree of grit, thereby activating a thin continuous film between the transfer belt and the paper web. Once the original degree of grit has been recovered from the exit of the Ni-30, the transfer belt can release the paper web to a permeable fabric, such as a dryer pick-up fabric, with the lowest possible vacuum.

The patented track transfer belt comprises a bone reinforcing support having a paper-facing side and a back side, and having a polymeric coating on the paper-side, which includes a balanced jar with portions of at least one polymer. This balanced distribution is in the form of a polymeric matrix which may include both water-repellent and wettable polymeric moieties. The polymeric coating 5 may also contain a particulate filler. The reinforcing pad is intended to prevent deformation of the transfer belt in the longitudinal and transverse directions, and may consist of a woven fabric and may also be endless or seam-sealed in an endless manner during installation on the peri-machine. In addition, the reinforcing support may comprise a textile material and may be applied to one or more layers of fibrous fiber by needling. Textile material means fibers or fine yarns of natural or synthetic origin intended for the manufacture of textiles. The backside may also be impregnated and / or coated with a polymeric material.

To date, such radial transfer belts for paper mills have been manufactured in endless form, i. as having a reinforcing support, either woven into an endless form or bonded to one endless form before being coated with a polymeric material. However, installing an endless transfer belt on a paper machine is a time consuming and technically complex task. Needless to say sel->; It is understood that paper production must temporarily cease while the transfer belt is being installed or replaced. Since the installation of the endless belt cannot be accomplished by twisting or threading the belt through and around parts of the papermaking machine 30, it must be mounted from the side of the machine. This is obviously much more time-consuming and labor-intensive than installing a belt with open ends, since machine parts such as press rolls need to be supported while the transfer belt slides into the space between them. Needless to say, supplying a web conveyor belt that can be seamed would significantly reduce the time and effort required to install or replace one on a paper machine.

WO 93/17161 discloses a bondable web comprising a textile fabric 5 provided with at least one side and at least a portion thereof through a thickness of a thermoplastic material. When the thermoplastic material is thermally softened, it at least partially fills the fabric structure of the fabric. At the edges of the respective ends of the strip there are connecting loops 10 formed in the textile fabric and cooperating with the connecting loops similarly formed at the opposite end of the strip so that a detachable joint can be formed. In order to allow easy web fitting and to provide the 15 strips with the same features as the remainder of the web, no plastic filler is applied to the textile fabric interconnecting means with a width calculated from the fabric edge and inward corresponding to at least 20 loops over with the head.

The difficulty of supplying a conveyor belt with open ends or which can be joined by seams is likely to be a trace from the seam region to the paper web. Because the web conveyor belt passes the paper web through the press nip and is in direct contact with the web web therein, the slightest difference in web seam area thickness, compressibility and surface hardness leaves a mark on the web.

The main object of the present invention is to provide a seam-connectable radial transfer belt, and methods for sealing the seam region, wherein the seam region acquires properties substantially identical to the remaining 35 parts of the radial transfer belt, leaving no seam the paper web.

It is also an object of the present invention to disclose a seamable conveyor belt so that the time and labor required to install and replace such a belt on a paper machine can be reduced.

It is a further object of the present invention to provide a seamable transfer belt so that existing paper machines can be easily modified or adapted to receive the transfer belt disclosed in US 5,298,124, whereby the openings can be removed therefrom.

Accordingly, the present invention includes several methods of sealing the seam areas of a coated seam after it has been reattached in a paper machine to one endless shape. The object of the invention is to close the seam completely while being given the same compression properties as the rest of the strap under normal nip loading. The closing technique also dissipates the bending stress, which otherwise could be centered on the 20 overlapping interconnections. This improves the bending fatigue strength of the joint.

The process of the invention is characterized in what is set forth in claim 1.

Further, the papermaking belt 25 of the invention is characterized in what is disclosed in claim 41.

Briefly, in both methods, the treated seam region of the belt is filled from the non-paper side using foam of polymeric material. If necessary, the paper side of the belt may be filled using the same or a different polymeric material, not necessarily foam. In one method, the foam compound is blown and cured under contact pressure using a heating source having level-35 plates and a suitable release medium. During heating, the foam compound expands and fills all voids, including the coating connection line. After curing, the heater is removed and the coated surface is finished by grinding, if necessary, to remove the surface gloss. The chemistry of the foam and the geometry of the heater level plates determine the total compressibility of the joint area in the nip.

In another method, the polymeric material is pre-foamed before being applied to the seam region and heat cured in the same manner as above.

In yet another method, the seam region may be coated with a solid foam strip of polymeric resin material or a fibrous strip of fibrous vanilla. Each of these can be secured to the seam area with an adhesive.

In yet another method, the backing of the coated seamless web may include machine-directional multi-filament yarns. During the manufacture of the seam, the multi-filament yarns may be cut and disposed off the paper side 20 of the coated seam to form a fibrous pad below the seam to replace the missing pad in the seam region. In a papermaking machine, after filing, the multi-filament yarns can be held in place using, for example, an injection adhesive.

25 The coated belt may have a structure in which the seam loops can be adapted to the center of the structure below the coating and the back side on the layer, which may include a woven fabric, a knitted fibrous batt material, fabric, a polymeric foam, a polymeric 30 resinous coating or some other non-woven structure agent is less compressible than needle-woven fabric or a combination of these.

Alternatively, the back side layer 35 may be omitted entirely. The coated surface (paper side) can be sealed using a polymeric material, preferably one which is non-foamable and which cures at room (ambient) temperature or faster when heat is added.

Specifically, the method of sealing a seam in a polymeric resin-coated paper-processing belt according to the present invention involves combining a needle-sealed papermaking fabric with a needle and coating the outer surface of the fabric (paper side) with a polymeric resin material. After curing the polymeric resin material and optionally finishing the surface, the needle is removed and the polymeric resin material is cut across the seam to leave the newly coated fabric in a shape with open ends. The strap is then delivered to a paper mill where it is reconnected to the endless needle-15a paper machine during installation. The seam is then covered on the uncoated sides of the belt, i.e.. on the inner surface (on the non-paper side), with an encapsulating material in the seam area. The encapsulating material may be a viscous paste comprising a polymeric substance and a porosity agent. The seam is then gradually heated to a temperature at which the porosity agent decomposes to release gas, forming a foam from the viscous paste. The foam fills the voids in the seam and can pass through the gap formed when the coating material was cut. The joint is then heated to the curing temperature of the foam. Curing may be bonded to the gap or may be bonded with a separate agent.

Alternatively, the encapsulating material may be a pre-foamed polymeric material in which the polymeric material has been foamed before being applied to the seam region. Pre-foaming can be achieved by using a blowing agent which decomposes at or near room temperature. Low density filler materials containing expanded thermoplastic microspheres may be used in place of the porosity agent. As soon as the pre-foamed polymeric material is applied to the seam region, it is cured as above with the same result.

Instead of the liquid encapsulating material, a solid foam strip of polymeric material or a fibrous strip of fibrous cotton can be used as an encapsulating material. In either case, the strip may be secured to the seam area by means of an adhesive and the gap may be bonded with a separate material.

Alternatively, the undercoat of the coated seamed belt 10 may include machine direction multi-threaded webs. The multi-filament yarns can be cut and arranged below the seam to form a fibrous filler there to replace the missing cotton wool. This fibrous filler can be held in place using, for example, 15 injectable adhesives.

The present invention also includes belts manufactured in accordance with the methods. Although the following discussion emphasizes the sealing of the web conveyor belt, the invention can also be used to seal a long nip press (LNP) belt or other polymer coated belt for the paper industry.

The present invention enables one skilled in the art of papermaking machine fabrics to control the compression of the 25 seams, eliminate or at least minimize nip formation. A further advantage of the present invention is that the distribution of foam or other material under the belt in the seam region reduces the tension forces of the coating joint. Finally, closing the coating joint may prevent water from penetrating through the belt and possibly premature end wear of the belt due to the opening of the lamination of the coating. It can also reduce the amount of traction 35 caused by the coating bonding line on the web.

In the following, the invention will be described in detail with reference to the accompanying drawings, in which: Figure 4 illustrates a method for sealing a seam by following the installation of a polymer resin coated paper converting belt on a papermaking machine, and is a cross-sectional view of the belt, Fig. 5 is a plan view of a transfer belt seam region 15 enclosed by an alternative embodiment of the present invention; Fig. 6 is a cross-sectional view taken along line 6-6 'of Fig. 5; Fig. 7 shows an alternative method for closing a sav-20 man. Figure 8 shows another method of sealing the seam, Figure 9 shows another method of sealing the seam, Figure 10 shows a modification of the method shown in Figure 9.

Figure 1 shows a description and general background of a representative press arrangement including a transfer belt for removing open passage in a paper machine. The figures 30 in Fig. 1 show the direction of movement or rotation of the members shown in the figure.

In Figure 1, the paper web 10, depicted by the dotted line, is initially conveyed to the right below the pick-up fabric 12, which prior to this has been picked up by the paper-web 10 from the forming fabric, not shown here.

The paper web 10 and the pickup web 12 advance toward the first vacuum transfer roll 14 around which a press fabric 16 passes and is oriented. Here, a suction from the inside of the first vacuum transfer roll 14 disengages the paper web 10 from the pick up fabric 12 and 5. The pickup fabric 12 then proceeds from this transfer point toward and around the first guide roll 18 and back, by means of additional guide rolls (not shown), to a position where it can again receive the papermaking web 10 from the forming fabric.

The paper web 10 then advances, as carried by the press fabric 16, toward the press nip 20 formed between the first press roll 22 and the second press roll 24. The second press roll 24 may be grooved, as shown by the dotted line inside the circle in Figure 1, to receive water that is discharged from the paper web 10 in the press nip 20. The transfer belt 26 runs around the first press roll 22 and is oriented through the press nip 20 with. In the press nip 20, the paper web 10 is compressed between the press fabric 16 and the transfer belt 26.

When exiting the press nip 20, the paper web 10 engages the surface of a transfer belt 26 having a surface smoother than the surface of the press fabric 16. Moving to the right of the press nip 20, the paper web 10 and transfer belt 26 reach a second vacuum transfer roll 28. The press fabric 16 is guided back to the first vacuum transfer roll 14 by the second guide roll 30, the third guide roll 32 and the fourth guide roll 34 30.

From the second vacuum transfer roller 28, the paper web 10 is transferred to a drying fabric 36 which passes and is oriented 35 around it. The drying fabric 36 conveys the paper web 10 to the drying section for the first drying drum 38.

11 111175

The transfer belt 26 advances to the right away from the second vacuum transfer roll 28 to the fifth guide roll 40, about which it is directed to the six guide roll 42, the seventh guide roll 44, 5 to the eight guide roll 46 and the ninth guide roll 48 which eventually returns it to the first clamping roll 22 again, the paper web 10 can be received from the press fabric 16.

As can be seen in Figure 1, the transfer belt 26 also removes the openings from the press arrangement shown, most notably the openings that are often present where the paper web 10 is moved from the press fabric 16 to the dryer fabric 36. The paper web 10 is 15 conveyor supported. Further, it should be noted that the paper web 10 is supported below the transfer belt 26 when exiting the press nip 20 because the water film on the transfer belt 26 is strong enough to support the paper web 10.

The manufacture of the seamless transfer belt of the present invention begins by obtaining an OMS on-machine-seamable coating (OMS) and temporarily joining it to an endless shape, the inner surface of the endless loop thus formed forming a non-paper side of the transfer belt. An illustration of such a press fabric seam region is shown in Figure 2.

In particular, Fig. 2 shows a seam region 30 50 in a seam OMS overlay 52 comprising seam loops 54 formed by machine direction yarns 56 along the width of the open ends of the press fabric 52. When such a coating tray 52 is to be sealed to endless shape, the two ends 35 are brought together, the end seaming loops 54 interposed with each other to form passage 58, and the needle 60 is guided through the passage 58 12111175 to interconnect the seaming loops 54. Figure 2 shows. Alternatively, needle 60 may be a multifilament needle or a twisted monofilament needle.

Figure 2 shows one type of coating substrate 52 that can be used. This coating substrate 52 includes machine direction transverse yarns 62 and fibrous bobbin fabric 64, knitted into weft fabric 66 formed by weaving machine direction yarns 56 and machine direction transversal yarns 62. Alternatively, instead of or together with the fiber bobbin fabric 64, the back of the coating substrate 52 may include a woven fabric, a polymeric foam, a polymeric resin coating, either the same or 15 different than that used on the paper side of the coating substrate 52, or other nonwoven structure, a material less compressible than a knitted fabric a combination of these. Substance that is less compressible than needled fibrous cotton fabric is an alternative for forming a seam to be more compressible to obtain similar properties between the seam region and the rest of the belt conveyor belt.

Alternatively, the back side layer 25 may be omitted entirely. In this case, the coated surface (paper side) is sealed using a polymeric material, preferably non-foamed, which can be cured at room (ambient) temperature or faster if heat is added when the coated sealed belt is mounted on a paper machine.

As noted above, the coating substrate 52 is temporarily joined to an endless shape by the outer surface of an endless loop formed 35 in this manner, being the paper side of the transfer belt in a suitable device at the manufacturing facility so that it can be subjected to longitudinal tension , which it supports while traveling in a paper machine.

In such a state, the exterior 5 of the closed loop formed from the coating substrate 52 is coated with a polymeric coating 68 containing a balanced distribution of at least one polymer segment to form a polymeric matrix which may include both hydrophobic and hydrophilic polymeric moieties. The polymeric coating 68 may also include a 10 particle filler 70 as disclosed in US 5,298,124.

The coating 68 is then cured and subsequently refined to obtain a transfer belt 72 comprising a seam region 50 having a uniform thickness and having a surface topography provided.

At this point, the transfer belt 72 may be pivoted in the opposite direction (inverted) if its length and width permit it, without causing any damage. Alternatively, the function described below may be performed from within the closed loop formed by the transfer belt 72 as long as; as the means allow the worker to perform the function within it without damaging the transfer belt 72.

In either case, needle 60 is removed 25 and transfer belt 72 is folded in seam region 50 as shown in Figure 3. This means that the transfer belt 72 is folded in such a way that the cover 68 is inside the fold. Folding removes seam loops 54 from their interlaced space 30 and places them in a structure that can be represented by two spaced parallel rows of upward seam loops 54. Between each parallel row is a portion 68 of the coating 68. between each row of parallel seam loops 54 to return the transfer strap 72 to a shape having open ends without cutting any of the seam straps 54.

In this form, with open ends, the transfer belt 72 is packaged and transported to a paper mill for installation on a paper machine, such as the one shown in Figure 1, in the same way an OMS press fabric can be mounted. It will be recalled that in Fig. 1 the transfer belt is represented by reference numeral 26.

Referring again to Figure 1, the sealable transfer belt 72 is mounted on a papermaking machine in place of the endless transfer belt 26 with the polymer coating 68 facing outward. A yarn that is more flexible than the coarse monofilament needle 60 can be used as the final needle. Now it remains to be ensured that the seam region 50, and in particular the part 74 of the polymer coating 15 68, which was cut open to provide the open ends of the transfer belt 72, does not leave marks on the papermaking web 10.

Figure 4 shows what the seam region 50 of the seam transfer belt 72 looks like when the needle 76 20 is used to reconnect it to an endless shape in a paper machine. Slit 78 remains in the polymeric coating 68 more or less directly above your seam seam 54 and less severely, fracture 80 remains in the fibrous pad 64 directly below the seam lining 54. The loop / needle assembly makes the seam region 50 slightly different from the other seam transfer belt 72, and allows the seam region 50 to leave marks on the paper web to which it is in contact.

The needle 76 may be a coarse monofilament needle, a multifilament needle, a twisted multifilament needle, a twisted monofilament needle, or a combination needle of any one of these types.

The foam produced by mixing the liquid-35 polymeric resin with the blowing agent to form a viscous paste, followed by heating and curing the viscous paste, is used to fill and seal the joint area 50 and the gap 78. Solvent-free urethane compound such as Adiprene L- 100 from Uniroyal or one based on a polyether-ri type prepolymer can be used for this purpose. The following is an example solvent solvent-free urethane compound that can be used for this purpose.

Component Weight (%) 10 Polyether / TDI-polyurethane prepolymer (4.1% NCO) 76.9

Protected aromatic amine (equivalent weight - 217) 15.4

Endothermic compound 15 (blowing agent) 7.7

Other ingredients such as fillers, plasticizers, and catalysts may be added as needed. The blowing agent, which is typically a solid particulate material which decomposes to release; the gas is almost immediately, when heated to a characteristic temperature, mixed with a liquid polymeric resin. The temperature at which the porous agent is activated is typically lower than the temperature at which the polymeric resin agent cures. For example, the temperature at which the porous agent decomposes (or explodes) may be 115 ° C, while the temperature at which the polymeric resin agent cures may be 130 ° C, which is the effective temperature for Adiprene L-100. The blowing agent will cause the viscous paste to foam and expand, filling the voids in the seam region 50 and may also pass through the slot 78. In this way, the gap 78 can be glued and the same compression and thickness applied to the seam region 50 as the remainder of the transfer belt 72.

The viscous paste which produces the foam 82 is preferably first provided on the non-paper side or inner side of the seam region 16111175 of transfer belt 72 at a point on the paper machine where staff can easily access the paper machine. For example, the area adjacent to the seventh guide wire 44 shown in Figure 1 may provide such easy access. The viscosity of the foam 82-producing viscous paste is preferably adjusted so that it can be easily applied regardless of the orientation of the surface to be coated (horizontal, vertical, inverted, 10, etc.).

Preferably, the viscous paste may be applied to the non-paper side of the transfer belt 72 over the seam region 50 such as 0.25 inch (0.64 cm) on each side of the seam so that the bending tension 15 can be distributed across the seam region rather than centered at one location. to slot 78.

Once the non-paper side 50 of the seam region 50 of the transfer belt 72 is sealed with a viscous paste, it can be covered with a material 84 that the curing foam 82 (obtained from the viscous paste) does not adhere, such as heat-resistant irocouple, Teflon-coated fiberglass and other substances.

The paper-side side of the seam 25 region 50 of the seam-joining transfer belt 72 may also be covered with a viscous paste that produces foam 82, or optionally coated with another polymeric coating agent such as that used to make the coating 68 to fill all re-creases in slot 78. once the paper-side seam region 50 of the transfer belt 72 is coated in either way, it may be covered with a substance 84 which is not adhered by cured foam 82 (obtained from a viscous paste) or other polymeric coating material 35.

The heat source can be used to foam the viscous paste and cure the foam 82. As a precursor, the heat strips 86 may be formed of aluminum pieces, typically 0.5 inches thick and wide enough to extend over the seam region 50 in the direction of movement of the belt. The heat strip members 86 include a heating member for gradually heating them from ambient temperature to the temperature at which the foam is cured and beyond.

Both heat strips 86 are pressed against each side of seam region 50 so that the thickness of seam region 50 becomes the same as the rest of transfer belt 72. At such a point, the temperature of the hot strips 86 is allowed to rise from ambient temperature to the swelling temperature, where the porous agent contained in the viscous paste decomposes and expands the paste, forcing it into the void spaces of the seam region 50. Heating of the strips 86 is continued above this explosion temperature up to the curing temperature of the polymeric resin which can harden almost instantaneously at this temperature. Preferably, the curing heat is maintained for a sufficient period of time to ensure that the curing process is complete.

Instead of using two heat strips 86 as described above, the heated carriage 100 can be transported across the seam area. Fig. 5 shows a heated carriage 100 which is pulled over the width of the transfer belt 72 by following the seam area 50 at a rate such that the porous agent in the viscous paste decomposes and expands the squeeze to force the seam area 50 into the empty spaces. ; and the curing temperature of the polymeric resin material is obtained and maintained for a time sufficient to ensure that the curing process is complete. The underside of seam region 50 is preferably supported during this process so that heated seam 100 35 can compress seam region 50 and ensure that the thickness of seam region 50 can be the same as the thickness of the rest of the transfer belt 72.

111175 18

Figure 6 is a cross-sectional view taken along line 6 '- 6' in Figure 5. The heated carriage 100 is pulled across the conveyor belt 72 following the seam region 50 by a lead 102. The support 104 may be fitted under the seam region 50 so that the heated carriage 100 may be squeezed against it although the tension in the transfer belt 72 could provide suitable support for slide 100.

Viscous paste having a very long service life at room temperature 10 can be used to work step by step across the seam in case the seam does not pass exactly across the belt. Long service life means that the paste material can be stored for a long time without changing its properties. If the paste has a long service life, the heat strips 86 need not be as wide as the transfer belt 72, and as discussed above, step by step operation across the seam can be accomplished, such as by using heated 20 carriage 100 to seal it in accordance with the present invention.

After curing, the material 84 applied to the non-paper side and / or paper side of the seam region is removed and the transfer belt 72 25 can be displaced such that the seam region 50 overlooks the roll, such as the seventh guide roll 44 in FIG. the surface of the polymer coating 68 may be softened with a light sandpaper abrasion to remove the sponge filler that protrudes in the seam region.

Alternatively, the slot 78 may be bonded with a separate material. The following is an example of a combination that can be used as a stand-alone substance:

Ingredient Weight (%)

Polyether / TDI Polyurethane 35 19 111175 prepolymer {4.1% NCO) 76.9

Protected aromatic amine (equivalent weight - 217) 15.4

Kaolin clay 7.7 5

As an alternative to using a viscous paste prepared by mixing a liquid polymeric resin with a blowing agent as described above, followed by forming a foam 82, followed by applying a viscous paste to the seam area, a pre-foamed liquid polymeric resin may be used instead. By "pre-foamed" is meant that the foaming is performed before the substance is applied to the seam region 50. This can be accomplished by using an endothermic nucleating agent (blowing agent) which decomposes at or near room temperature. These agents are easy to obtain and are well known to those skilled in the art.

Instead of such a blowing agent, the low density excipient may replace it in the solvent-free urethane compound example used

i ·. I

·; to fill the seam area 50 as described above.

A certain low density filler takes the form of a heat-softening microsphere containing a liquid hydrocarbon. These microspheres expand upon heating and remain in an expanded state as they cool. Even when expanded, they remain very small - about one micron in diameter - and very small - 30 heights. The use of a low density filler type allows the user to precisely adjust the density of the foam to be applied to the seam area. This means that the microspheres can be gradually added to the mixture until the desired density is obtained. An example of such a mini-35 heel filler is Expancel DE 551, which consists of pre-expanded, thermoplastic hollow microspheres, which are added to a "pre-foamed earth" polymeric material used to seal the seam.

As a further alternative, a fixed foam strip 88 may be applied to the seam area 50 as shown in Figure 7 5. The solid foam strip 88 can be made from the so-called "foam strip" described above. a "pre-foamed" liquid polymeric resin or a liquid polymeric resin containing a low density filler (microspheres). The solid foam strip 8810 may be either thermoplastic or heat curable depending on the manner in which the curing agent incorporated in the liquid polymeric resin material interacts with the end groups of the polymer chains. When the strip 88 is thermoplastic, it can be secured to the seam region 50 by a heat source, such as a heat strip 86. Alternatively, it may be affixed here with an adhesive as described above to secure the gap 78, which must be pre-applied prior to the strip 88. When the strip 88 is a curing mass of 20, it may be secured to the seam region 50 by adhesive shown above for securing slot 78. Finally, either heat-softening or heat-curing strip 88 may be provided with a heat-active adhesive for attachment to the seam region 50. An example of a heat-active adhesive that can be used for this purpose is a heat-softening polyurethane (e.g., inhibitory resin) used as a dissolving binder and dried.

Another alternative is shown in Fig. 8, wherein a fibrous strip 90 of fibrous batt can be applied over the seam area 50 instead of the solid foam strip 88. The adhesive may be the same as the one shown above for adhering the slot 78.

In each of these alternative representations, slot 78 may be glued with a separate material, such as the one shown above.

21 111175

The adhesive compound may be applied to the slot 78 before any liquid polymeric resin 82, pre-foamed solid strip 88 or fibrous strip 90 is applied to the seam region 50.

5 on the non-paper side of the belt.

A further alternative is shown in Figures 9 and 10. In each of the Figures, the multi-filament yarns are oriented on the base fabric 66 in the machine direction. The multi-filament yarns may be multifilament yarns, twisted staple fibers 10 or textured filament yarns.

It should be noted that in fibrous material 64, the seam region 50 has a spacing 106. When making the seam region 50, the multi-strand yarns 108 are cut across and. arranged away from the polymer coating 68 to form a fibrous filler under the seaming loops 54 to replace the fibrous matrix 64 which is missing from the intermediate 106. The multi-filament yarns 108 may come from either side of the seam region 50 as shown in Figures 9 and 10. Preferably, the multifilament yarns 108 are embedded in the base fabric 66 during the weaving process, but may also be inserted after weaving with a needle, such as in the tufting process.

After installation on a paper machine, the,,; filament yarns 108 may be held in place using, e.g., a sprayable adhesive such as a commercially available acrylic aerosol adhesive. Slit 78 in polymer coating 68 may be closed using a polymeric material and preferably one that has not been foamed. A polymeric material which is curable at room temperature (ambient) can be used for this purpose as well as one which is accelerated by heating.

In all of the above embodiments of the present invention of the present invention, non-foamable polymeric materials are cured not only by heat or ambient temperature, but also by 22111175 ultraviolet light and other techniques known to those skilled in the art.

It is to be understood that the purpose of each of these alternatives is essentially to encapsulate the looped seam and to provide the encapsulated seam with the same compression properties as the rest of the strap. The method chosen in each given case is that which can be accomplished in a shorter time by the factory personnel, thereby minimizing the time that the paper machine 10 has to stand and is not used for papermaking.

The invention is not limited to the foregoing variations, but its embodiments will be apparent to those skilled in the art and may vary within the scope of the inventive idea set forth in the appended claims.

Claims (62)

A method of sealing a seam (50) on a polymer resin coated paper processing belt (52, 72), comprising the steps of: 5. providing a needle-sealing paper machine fabric (66) having a paper side, a non-paper side and seaming loops (54) (50); attaching the needle-stitching fabric to the endless form 10 by a first needle (60) directing the first needle through a passageway (58) formed when the seam loops (54) at each of the widthwise edges are interlaced with one another; - coating the side of the paper machine fabric with a first polymeric resin material (68); - curing the first polymer resin material (68) to produce a polymer resin coated paper processing belt; removing the first needle (60); 20. cutting the first cured polymeric resin material at the seam (50) to position the strap in an open structure; - mounting the belt on a paper machine; - connecting the belt to the endless shape with a second needle (76) by guiding the second needle through a passageway (58) j 7 formed by seaming the seaming loops on the widthwise edges of the needle-bonding paper machine with a gap (78) 30 in the first polymeric resin material 54) in the vicinity; characterized in that the seam is coated on the uncoated side of the strap with an encapsulation material (82, 88, 90, 108) such that the seam obtains compressibility properties substantially identical to the other portion 35 of the strap. A method according to claim 1, characterized in that in the coating step of the seam (50): - providing a viscous paste comprising a second polymeric resin material (82) and a blowing agent; 5. applying a viscous paste to the seam; - causing the viscous paste porosizing agent to form a gas, whereby the viscous paste may be foamed; and - curing the foam. A method according to claim 1, characterized in that in the coating step of the seam (50): - providing a pre-foamed liquid polymeric resin material comprising a second polymeric resin material 15 (82); - applying a pre-foamed liquid polymeric resin to the seam; and curing the pre-foamed liquid polymeric resin. Method according to claim 3, characterized in that the liquid polymeric resin material is pre-foamed by disintegrating the blowing agent mixed with the second polymeric resin material (82) before being applied to the seam (50). A method according to claim 3, characterized in that the liquid polymeric resin material is pre-foamed by mixing the second polymeric resin material (82) with the low density filler 30 before being applied to the seam (50). Method according to claim 5, characterized in that the low-density filler comprises expanded thermoplastic microspheres. Method according to claim 1, characterized in that in the coating step of the seam (50): - a solid foam strip (88) is provided which is a second polymeric resin material; and attaching a fixed foam strip (88) to the uncoated side of the strap over the seam (50). Method according to claim 7, characterized in that the fixed foam strip (88) is fixed by means of a heat source (86, 100). Method according to Claim 7, characterized in that the solid foam strip 10 (88) is fixed by means of an adhesive. A method according to claim 1, characterized in that, in the coating steps of the seam (50): - providing a fibrous strip 15 (90) of fibrous pad; and - attaching the fibrous strip (90) to the uncoated side of the strap over the seam (50). A method according to claim 10, characterized in that the fibrous strip 20 (90) is fixed with an adhesive. The method according to claim 1, characterized in that the needle-sealing paper machine fabric comprises machine direction multi-filament yarns (108), wherein in the seam coating step: 25. cutting the multifilament yarns (108) from at least one of the widthwise edges of the needle-sealable paper machine fabric; and - arranging the ends of the multi-filament yarns (108) over the seam (50) on the uncoated side of the belt. A method according to claim 12, characterized in that the ends of the multi-threaded yarns (108) are held in place by means of an adhesive to be injected into the seam (50). Method according to Claim 12, characterized in that the filaments (108) are multifilament yarns. Method according to claim 12, characterized in that the multi-filament yarns (108) are braided staple fiber yarns. A method according to claim 12, characterized in that the filament yarns (108) 5 are textured filament yarns. The method of claim 1, characterized in that the first needle (60) is a coarse monofilament needle. The method of claim 1, characterized in that the first needle (60) is a multifilament needle. Method according to claim 1, characterized in that the first needle (60) is a twisted monofilament needle. Method according to claim 1, characterized in that the second needle (76) is a coarse monofilament needle. A method according to claim 1, characterized in that the second needle (76) is a multifilament needle. A method according to claim 1, characterized in that the second needle (76) is a twisted monofilament needle. The method of claim 1, characterized in that the second needle (76) is a composite needle comprising a coarse monofilament needle. 23 111175 The method of claim 1, characterized in that the second needle (76) is a composite needle comprising a multifilament needle. A method according to claim 1, characterized in that the second needle (76) is a composite needle comprising a twisted monofilament needle. A method according to claim 1, characterized in that the coating is carried out on the paper side 27111175 of the needle-bonded paper machine and further comprises the step of needling the non-paper side of the needle-sealing paper machine together with the fibrous batt. The method according to claim 1, characterized in that the coating step is carried out on a paper side of the needle-sealing paper machine fabric and further comprises the step of coating the non-paper side of the needle-sealing paper machine fabric with a first polymeric resin material. A method according to claim 1, characterized in that the coating step is carried out on the paper side of the needle-sealing paper machine fabric and further comprises the step of coating the non-paper side 15 of the needle-sealing paper machine fabric with a third polymeric resin material. A method according to claim 1, characterized in that the coating step is carried out on the paper side of the needle-sealing papermaker's fabric and further comprises the step of bonding the material 20 which is less compressible than the needle-web of fibrous material to the non-paper side. A method according to claim 1, characterized in that the needle-sealed paper machine fabric comprises machine-direction yarns (50), and that the seam loops (54) are formed from machine-direction yarns. A method according to claim 1, characterized in that the method further comprises the steps of grinding the first polymeric resin material (68) immediately after the curing step so that the paper-processing belt coated with the polymeric resin material becomes uniformly thick and has the desired surface properties. The method according to claim 1, characterized in that the method further comprises the step of coating the encapsulating material (82, 88, 90, 28111175108) immediately after the step of applying it to the seam (50). A method according to claim 2, characterized in that the method further comprises the step of applying a viscous paste on the seam (50) to the side of the belt having the first polymeric resin coating (68). The method according to claim 33, characterized in that the method further comprises the step of coating the viscous paste on its seam. A method according to claim 2, characterized in that the steps of causing the blowing agent to produce gas and curing the foam are carried out while the seam (50) is compressed so that the seam can have the same thickness and / or compressibility properties. than the other part of the paper resin belt coated with a polymer resin. The method according to claim 1, characterized in that the method further comprises the step of grinding the seam (50) on the side of the polymer resin-coated paper processing belt on which the first polymeric resin material (68) is, to smooth the seam. A method according to claim 2, characterized in that the step of causing the blowing agent to produce gas to produce foam from the viscous paste forces the foam into a gap (78) in the first polymeric resin material (68) and curing the foam causes the gap to glue. The method according to claim 1, characterized in that the method comprises the step of applying the encapsulating material at a distance to each side of the seam (50) to cover the seam and the area on either side so that bending stresses in the polymer resin coated paper processing belt can be distributed is wider than the seam to release the slit (78) from bending tension, and so that the seam region may have a resistance to bending equal to that of the rest of the belt. The method of claim 1, further comprising the steps of gluing the slit (78) with a third polymeric resin material and curing the third polymeric resin material. A method according to claim 39, characterized in that the method further comprises the step of grinding the seam (50) on the side of the polymer resin coated paper processing belt on which the first polymeric resin material (68) is to smooth the seam. 41. A polymer resin-coated paper processing belt comprising a 20-needle-seamable paper machine fabric having seam loops (54) formed by machine-direction yarns (56) on its two widthwise sides and joined to an endless paper-side side. and a non-paper side 25, with a needle (76) guided through a passageway (58) defined by the interlacing of the seam loops (54), thereby forming a seam (50) for the belt; - a coating (68) of a first polymeric resin material on a paper-side side of a needle-sealed papermaker's fabric with a gap (78) at the seam; characterized in that the strap comprises an encapsulating material (82, 88, 90, 108) covering the seam (50) on the non-paper side of the needle-sealing paper machine fabric 35. Belt according to Claim 41, characterized in that the encapsulating material is a foam (82) of a second polymeric resin material which impregnates the non-paper side of the seam (50) of a needle-sealing paper machine fabric. Belt according to claim 41, characterized in that the encapsulating material is a solid foam strip (88) of a second polymeric resin material, the solid foam strip being attached to a non-coated side seam (50) of the belt. Belt according to claim 41, characterized in that the encapsulating material consists of a fibrous strip (90) of fibrous batt, the fibrous strip being attached to the uncoated side of the strap over the seam (50). Belt according to Claim 42, characterized in that the foam (82) extends into the gap (78) and closes said gap in a closed form. A belt as claimed in claim 41, characterized in that the needle-sealable paper machine fabric comprises machine direction multi-thread yarns 20 (108) and that the encapsulation material comprises ends of the multi-thread yarns (108) extending at least from one side of said fabric to the non-coated side. (50) over. Belt 25 according to claim 46, characterized in that the ends of the multi-threaded yarns (108) are held in place by means of an adhesive to be injected into the seam (50). A belt as claimed in claim 46, characterized in that the filament yarns (108) are multifilament yarns. Belt according to Claim 46, characterized in that the multi-filament yarns (108) are braided staple fiber yarns. Belt according to Claim 46, 35, characterized in that the filament yarns (108) are textured filament yarns. 51. A belt as claimed in claim 41, characterized in that the belt comprises a fibrous swab which is needled on the non-paper side of a needle-sealing paper machine fabric. Belt according to Claim 41, characterized in that the belt further comprises a polymeric resin coating on the non-paper side of a needle-sealed paper machine fabric. 53. A belt according to claim 41, characterized in that the belt comprises a woven fabric 10 attached to a non-paper side of a needle-sealing paper machine. 54. A belt according to claim 41, characterized in that the belt comprises a polymeric foam which is attached to the non-paper side of a needle-sealing paper machine fabric. 55. A belt as claimed in claim 41, characterized in that the belt comprises a material which is less compressible than a needled web of fibrous cotton material attached to a non-paper side of a needle-sealing paper machine. A belt as claimed in claim 41, characterized in that the needle (76) is a monofilament needle. The belt of claim 41, characterized in that the needle (76) is a twisted monofilament needle. 58. A belt as claimed in claim 41, characterized in that the needle (76) is a multi-filament needle. 59. A belt as claimed in claim 41, characterized in that the needle (76) is a composite needle comprising a monofilament needle. Belt according to Claim 41, 35, characterized in that the needle (76) is a composite needle comprising a twisted monofilament needle. Belt according to claim 41, 32111175, characterized in that the needle is a composite needle having a twisted multifilament needle. Belt according to Claim 41, characterized in that the slot (78) is closed in a closed form by a cured third polymeric resin material. 11H175 33