GB2078609A

GB2078609A - Reinforced paper products

Info

Publication number: GB2078609A
Application number: GB8021005A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-06-26
Filing date: 1980-06-26
Publication date: 1982-01-13
Also published as: GB2078609B

Abstract

A wire reinforced paper structure comprises a plurality of longitudinally extending spaced parallel metal wires and first and second paper layers, said paper layers being adhesively secured together along their mating surfaces, characterized in that said first paper layer comprising a plurality of spaced parallel strips 32, said plurality of longitudinally extending metal wires 52 being disposed in the spaces 31 between the strips, the depth of the spaces corresponding to the height of the wires disposed therein and the width of each of said spaces corresponding to the total thickness of said wires disposed therein, whereby the wires are firmly held in said channels so that exposing of the wires upon cutting of said reinforced paper structure is inhibited. The structure may be used in the production of corrugated boards. <IMAGE>

Description

SPECIFICATION Reinforced paper products The present invention relates to metal wire reinforced paper products and corrugated board.

While it is known to employ wires as reinforcing elements for paper products (see for example U.S. Patent No. 4,203,790 to Chavannes, the applicant herein, which corresponds to British Serial No.

30722/76, filed July 23, 1976), problems have been encountered with the known products due to the incompressibility of wire and the relative weakness of paper vis-a-vis metal wires. One such problem occurs upon cutting of the known metal wire reinforced paper products. Due to the incompressibility of the wire and the wear tear strength of paper, jagged edges often result as a result of a cutting operation.

In addition, the cutting blades often tend to grip the wires during cutting resulting in the ripping of the paper layers and exposing of the wires. The resultant product has a number of disadvantages. The most significant problems relate to the exposure of the wires which results in hazardous operations for the operators, increased labor costs due to the delicacy with which the products may be handled, possible jamming of material handling equipment, etc.

It may be that known metal reinforced paper products can be cleanly cut if great care is taken in ensuring that the cutting instruments are sharp, always aligned, and maintained in top working order so as to produce clean, smooth cuts in all instances, irrespective of the material being cut. However, such requirements are not practical for the production of large quantities of reinforced paper laminates, particularly in the corrugated industry where the cost of the product greatly depends on the speed of the operation producing the products. Also, it is to be noted that in the corrugated industry exceptionally high grade quality of papers are not always used in making corrugated cardboard and thus may have a tendency to magnify the problems respecting the cutting of the formed metal wire reinforced laminate.

A further problem with the known product, such as the type taught in the aforementioned Chavannes patent, occurs because relatively thick wires are positioned between relatively thin paper webs which are adhered to one another. This results in a product having a series of ridges on at least one of the outer surfaces of the resulting paper structure. This ridged or contoured surface is difficult to print on, is unaesthetically pleasing, and requires a relatively large amount of glue or adhesive for adequately adhering the paper webs together with the wires therebetween.

An additional problem encountered with the known products occurs during a corrugating process in which the wire reinforced paper product is corrugated transversely of the longitudinally extending wires. If the wires are not firmly held in place during such process, the wires may slip and move, thereby causing tearing, ripping or shredding of the paper which is both unaesthetic and tends to expose the wires with the resulting disadvantages noted respecting cutting operations.

The present invention teaches a wire reinforced paper structure in which the wire reinforcing elements are disposed in and firmly held in place in channels defined in the paper layers. Thus, in accordance with the present invention, an improved wire reinforced paper structure is provided in which a plurality of reinforcing wire elements are disposed in spaced parallel channels formed in one surface of a paper layer. The depth of the channels is less than the thickness of the first paper layer and corresponds to the height of the wires disposed therein so that a relatively smooth, aesthetically pleasing outer surface is provided when a second paper layer is adhesively secured to the surface of the first paper layer.The depth and width of the channels are such that the wire reinforcing elements are tightly held in place between the two paper layers and the sides of the channels, and are thus prevented from slipping or moving laterally relative to the channels. Therefore, both during a corrugation operation on such a paper structure and/or a cutting operation, the wires are firmly held in place in the channels are are inhibited from moving relative to thereto. Thus, the wires will not be pulled out or from between the paper layers, thereby ripping the paper and possibly dangerously exposing the wires. In particular, in standard cutting operations, good, clean and acceptable cut edges are achieved on finished products in accordance with the present inventions.

According to the present invention, there is provided a wire reinforced paper structure comprising first and second paper layers adhesively secured together, spaced parallel channels disposed between the paper layers, and a plurality of longitudinally extending spaced parallel metal wires disposed in the channels, the depth of the channels substantially corresponding to the height of the wires disposed therein and the width of each of the channels being at least equal to the total width of the wires disposed therein, whereby the wires are firmly held in the channels so that exposing of the wires upon cutting of the reinforced paper structure is inhibited. The channels may be formed by adhesively securing a plurality of paper strips between the paper layers.

In order that the invention may be fully understood, it will now be described with reference to the accompanying drawings, in which: Brief Description of the Drawings Figure 1 is a diagrammatic view of the apparatus for manufacturing a wire reinforced paper structure in accordance with the present invention; Figure 2 is a plan view taken along lines 2-2 of Figure 1, illustrating the cutting of the middle paper web to produce the series of channels for the wires in accordance with the present invention; Figure 3 is a cross-sectional view taken along lines 3-3 of Figure 1 showing the cut middle paper web; Figure 4 is a cross-sectional view taken along lines 4-4 of Figure 1 showing one of the outer paper webs with adhesive applied thereto; Figure 5 is a cross-sectional view taken along lines 5-5 of Figure 1 showing the middle paper web adhesively secured to an outer paper web;; Figure 6 is a cross-sectional view taken along lines 6-6 of Figure 1, similar to that shown in Figure 5 but with the wires positioned in the channels formed in the middle paper web; Figure 7 is a cross-sectional view taken along lines 7-7 of Figure 1, showing the other outer paper web with adhesive applied thereto; Figure 8 is a cross-sectional view taken along lines 8-8 of Figure 1, showing the wire reinforced paper structure of the present invention; Figure 9 is a plan view of the spool and guide arrangement utilized in the apparatus of Figure 1 for guiding of the plurality of wires in parallel relationship into the series of channels formed in the middle paper web; Figure 10 is a diagrammatic view of another embodiment of the apparatus for manufacturing another embodiment of wire reinforced paper structure in accordance with the present invention;; Figure 11 is a cross-sectional view taken along lines 11-11 of Figure 10 showing the cutting mechanism for cutting the middie paper web to produce a series of channels; Figure 12 is a cross-sectional view taken along lines 12-1 2 of Figure 10 showing the brushes in accordance with the present invention for cleaning the threads of cut paper from the middle paper web; Figure 13 is a cross-sectional view taken along lines 13-1 3 of Figure 10, showing the cut middle paper web adhesively secured to an outer paper web; Figure 14 is a cross-sectional view taken along lines 14--14 of Figure 10, showing two wires placed in each of the channels formed in the middie paper web adhered to an outer paper web;; Figure 1 5 is a cross-sectional view taken along lines 1 5-1 5 of Figure 10, showing another embodiment of the wire reinforced paper structure in accordance with the present invention; Figure 1 6 is a plan view of the spool and guide arrangement utilized in the apparatus of Figure 1 0, for guiding of the plurality of wires in parallel relationship into the series of channels formed in the middle paper web; Figure 1 7 is an enlarged perspective view in accordance with the present invention showing the edges of the wire reinforced paper structure taped with a water resistant tape; Figure 1 8 is a diagrammatic view of the apparatus for producing a wire reinforced corrugated material in accordance with the present invention;; Figure 19 is a greatly enlarged cross-sectional view at position 19 of Figure 1 8 showing the corrugated wire reinforced paper structure adhesively secured to one outer facing or liner; Figure 20 is a greatly enlarged cross-sectional view, similar to that shown in Figure 19, taken at position 20 of Figure 1 8 showing the wire reinforced corrugated paper structure adhesively secured between two outer facings or liners to form double-faced wire reinforced corrugated board in accordance with the present invention; Figure 21 is a cross-sectional view taken along lines 21-21 of Figure 20;; Figure 22 is a cross-sectional view, similar to that shown in Figure 21, in which the wire reinforced paper structure of the present invention is used in the outer facings or liners of the double-faced corrugated board as well as in the corrugated medium; Figure 23 is a cross-sectional view, similar to that shown in Figures 21 and 22, but with the wire reinforced paper structure of the present invention only being used in the outer facings or liners of the double-faced corrugated board; Figure 24 is an enlarged perspective view, partly in section and partly broken away, showing double-faced wire reinforced corrugated board in accordance with the present invention;; Figure 25 is a diagrammatic view of the apparatus for severing the wire reinforced laminate of the present invention into sections and placing the sections in side by side relationship with the reinforced elements disposed transversely of the direction of the movement of the severed sections; Figure 26 is a diagrammatic view of the apparatus for laminating the sections produced in accordance with the apparatus of Figure 25 to a web of wire reinforced paper laminate to form a structure having longitudinal and transverse reinforcing elements incorporated therein; Figure 27 is a greatly enlarged cross-sectional view at position 27 of Figure 26 showing the laminated wire reinforced paper structure having longitudinal and transverse reinforcing elements incorporated therein; and Figure 28 is an enlarged perspective view, partly in section and partly broken away, showing double-faced wire reinforced corrugated board in accordance with the present invention in which the laminated paper structure produced in accordance with Figures 25-27 forms the outer facing of the double-faced wire reinforced corrugated board, DETAILED DESCRIPTION OF THE PRESENT INVENTION Applicant's previous invention provided an improved reinforced paper product in which the corrugated medium of a corrugated board was formed from a paper structure having a plurality of parallel spaced wires adhesively secured thereto and corrugated transversely of the wires.The wire reinforcing elements served to materially increase the strength of the corrugated board, not only by reason of the wire itself, but because of the configuration of the resultant laminate embodying the wire elements, i.e. the triangular truss structure formed by the wire elements. Further, the utilization of the wire reinforcing elements in corrugated board in accordance with applicant's previous invention made it possible to obtain as much as three times the structural strength utilizing only a moderate weight paper with a 0.254 mm (i.e., 10 mil) wire at 6.35 mm (i.e., 1/4") wire spacing than was otherwise obtainable by the strongest corrugated board available at that time. This increased structural strength was with respect to compression and/or bending of corrugated board.

The improved wire reinforced paper structure in accordance with the present invention is both in furtherance of and in addition to the teachings of applicant's previous invention. In particular, according to the present invention, there is provided an improved paper structure in which the wire reinforcing elements are more firmly and rigidly held in place so that tearing or ripping of the paper and/or exposing of the wire elements upon cutting and/or corrugating the improved paper structure is inhibited.

It will also become apparent from the following description that various procedures may be utilized in the formation of the improved reinforced paper product of the present invention. In particular, the initial step in the formation of any such products involves the formation of a plurality of spaced parallel channels for the placement of wires therein. One such procedure and apparatus for accomplishing the same is illustrated diagrammatically in Figure 1. In this figure, a single drum 10 is provided on which the entire lamination process is accomplished to produce or manufacture the improved paper structure in accordance with the present invention. The drum 10 includes suitable means (not shown) for heating it in order to dry and/or cure the adhesive which is applied to the paper webs. For example, the heat may come from steam, hot oil, or other liquids.Initially, a paper web 12 is fed from a roll 14 about rollers 1 6, 1 8 and 20 onto the surface of the drum 10. An adhesive 28 contained in a trough 22 is applied by means of rollers 24, 26 to the surface of the paper web 12. The adhesive is preferably applied over the entire area of the web 12, as can be seen in Figure 4, but may instead just be applied in strips which correspond to the strips of paper to be adhered to web 12, as described below.

Also fed onto the drum 10 and onto the adhesively coated surface of the web 12 is a second paper web 30 which has been cut to provide a plurality of spaced strips. Web 30 is fed from a roll 34 about idler rollers 36, 38 and 40. A cutting drum 42, having plurality of spaced peripheral cutting knives or blades 44 about the circumference thereof serves to make a plurality of cuts 45 completely through the paper web 30. During this cutting operation, rollers 38 and 40 serve to hold the web 30 level. A steel comb or other device 46 having a plurality of fine teeth 48 is positioned behind the cutting roller 42. As best seen in Figures 1 and 2, the teeth 48 of the comb 46 pass through the paper web 30 and act to deflect and remove the threads of paper cut from the web 30 so as to provide a series of open spaces or notches 31 in the web 30.These scraps of paper which are removed fall onto a carrier mechanism 50 positioned below the passing web 30. As can be seen in Figure 2, the width of the teeth 48 corresponds substantially to the width of the open channel 31 cut in the web 30, and the spacing between the teeth 48 corresponds to the spacing of adjacent pairs of cutting blades 44 of the cutter 42. This spacing in turn corresponds to the desired spacing of the wires to be inserted in the channels formed in the web 30, to be described below.

The paper web 30 with the cut threads removed, as seen in Figure 3, consists of a plurality of spaced bands or strips 32. The spacing 31 between adjacent strips 32 corresponds to the thickness of the wire to be disposed therebetween. Likewise, the thickness of the paper web 30 and thus, the thickness of the individual bands 32 also preferably correspond to the thickness of the wires to be inserted in the channel 31.

The strips or bands 32 are fed about pressure roller 51 onto the adhesively coated side of the outer paper web 12 and onto the heated drum 10. The pressure roller 51 may be provided with a rubber or other resilient surface to urge the bands 32 into firm contact with the outer or bottom paper layer 1 2.

The roller 10 includes suitable means for heating it in order to dry the adhesive on the bottom layer 12 to secure the strips 32 in place. Of course, additional heating elements (not shown) may also be employed to accelerate the drying or curing process as the webs 1 2 and 30 are passed about the roller 10, in a well known manner.

As the web 12, with the bands 32 of the middle web 30 adhered thereto, is fed about the drum 10 a plurality of wires 52 are fed into the channels 31. This is accomplished by means of a guide roller 54 which guides the plurality of wires 52 delivered by a spooling arrangement 56. Preferably, this spooling arrangement 56 comprises a plurality or battery of individual spools 58 mounted on a common cylinder 60. The common cylinder 60 in turn is mounted on an axle 61 for rotation. As best seen in Figure 9, the individual spools 58 each hold a plurality of wires 52 which have been wound therein in compact relationship in order to provide the desired spacing for the wires to be guided into the channels 31.For instance, if a 6.35 mm spacing between the wires 52 is desired in the finished product, each of the individual spools 58 could be loaded or charged with, for example, eight wires 52 wound between the flanges 59 of the spools 58. For this 6.35 mm spacing, the flanges 59 would be on the order of 50.4 mm apart. By using this arrangement, it is possible to use a battery of wire extruding machines which run at a very high speed, for example, on the order of 609.6 meters per minute (i.e., 2,000 feet per minute), to charge each of the individual spools 58. That is, a battery of eight extruders running side by side could deliver eight wires at one time to charge a spool 58. The charged spool 58 is then mounted and keyed on the common cylinder 60.Further, use of spools 58 to hold a plurality of wires 52 minimizes the number of flanges 59 for the spooling arrangement 56. This is desirable since, as can be appreciated, each flange takes up a relatively large space when compared to the wires 52.

The wires 52 from the individual spools 58 are then guided between appropriate spaced peripheral flanges 62 (see Figure 9) of the guide roller 54 to guide the wires 52 precisely into the channels 31 on the webs 30 and 12 laminated together. As shown in Figure 1, the spooling arrangement 56 rotates in a counterclockwise manner while the guide roller 54 rotates in a clockwise manner The flanges 62 are of appropriate thickness and spacing so that a fine guiding arrangement is achieved. For this purpose, the spacing between individual flanges 62 corresponds approximately to the thickness of the wires 52 and the thickness of the individual flanges corresponds to the width of the individual strips of paper 32.

As noted previously, the thickness of the web 30 corresponds to the thickness of the wires 52 to be placed in the channels 31. Similarly, the spacing between the individual strips 32 (i.e., the width of the channels 31) also corresponds to the thickness of the wires 52 so that the wires 52 are firmly supported in position when they are fed into the channels 31.

After the wires 52 are fed into the channels 31, a second paper web 66 is adhesively secured to the laminated webs 30 and 12 to entrap the wires 52 therebetween. The web 66 is fed from a roll 64 about idler rollers 68, 70 and 72 and pressure roller 74 onto the heated drum 10 in overlying relationship with respect to the bands 32 and wires 52. An adhesive 28, contained in trough 76, is applied by means of rollers 78, 79 to one side of web 66 in a manner similar to the adhesive applied to one surface of the web 12 (see Figure 7). The pressure roller 74, as with pressure roller 51, may be provided with a rubber or resilient surface and maintained under pressure against the drum 10 in order that the web 66 is sealed and secured to the cut middle paper layer 30 (already adhesively secured to the lower web 12).This resulting laminated paper structure 90 is fed from drum 10 about rollers 80 and 82 and then onto a rewind or take-up drum 84. As noted above, the drum 10 is heated so as to dry and/or cure the adhesive applied to the various webs 12, 66. Alternatively, or in addition to heating drum 10, the wire reinforced laminated 90, before being wound on drum 84, could be passed through an oven heating means (not shown) to insure complete drying and/or curing. The laminated wire reinforced paper structure 90 wound on drum 84 may then be used for any desired purpose, such as forming a corrugated medium of double-faced corrugated board.

As can be appreciated, the resulting wire reinforced laminated structure 90 has the wires 52 tightly held in place in the channels 31 formed in the middle layer 30 and covered by the top and bottom layers 12 and 66. In this regard, it is to be noted that the channels 31 which receive the wires 52 have a cross-sectional area which is greater than the cross-sectional area of the wires 52 disposed therein. Further, the finished product 90 has smooth flat surfaces. This is aesthetically pleasing as well as functional in that the resulting laminate structure 90 may be readily adhered to the fullest extent possible to other materials for whatever desired purpose. Further still, the wires 52 will be firmly retained in place during any cutting operation or during corrugation, to be described hereinbelow.This in turn minimizes the risk of the wires 52 becoming exposed during further operations and causing damage and/or injury, particularly during cutting and/or corrugation of the laminate structure 90.

Figure 10 shows an alternative apparatus for producing a wire reinforced paper structure according to the present invention. In addition, the apparatus of Figure 10 is arranged so as to produce an alternative embodiment of the present invention. In this embodiment a double width channel is cut in the middle paper web for the placement of a pair of wire reinforcing elements in each of the channels so formed. In other words, the width of the channels in the middle layer will be at least twice the thickness of the wire to allow two wires to be inserted into each channel instead of just one. In this way an article with twice the strength may be achieved without having to increase the thickness of the resulting paper structure.That is, two wires each of a given thickness, say 0.254 mm, may be inserted in each channel instead of a single 0.508 mm thick wire being placed in the channel which in turn would require that the thickness of the middle layer would be increased to 0.508 mm.

In this embodiment shown in Figure 10, two heated drums 1 00, 102 are used for adhering the paper layers to one another. Again, suitable means (not shown) supply the heat in the drums 100 and 102. Initially, a paper web 104 is fed from roll 106 about idler rollers 108 and 110 and pressure roller 112 onto the surface of drum 100. The idler rollers 1 08, 110 serve to maintain the tension in the paper web 104 to insure an even feeding onto the drum 1 00. Further, pressure roller 112 is preferably provided with a rubber or other similar face so that pressure can be applied thereby to hold the paper web 104 and prevent slippage thereof with respect to the drum 100. This web 104 will become the middle web of the improved wire reinforced paper laminate of the present invention.

Referring to Figure 11, drum 100 is provided with a series of circumferential grooves 114 in its outer surface which are adapted to receive the cutting blades or knives 11 8 of a cutting roller 11 6. As noted above, a double width channel is to be cut in the middle layer 1 04. Thus, the spacing between the individual blades 11 8 of the cutting roller 11 6 is such as to produce the desired width of the channel, as well as to produce the desired spacing between channels.

A rotating brush assembly 1 24 is provided adjacent to the cutting roller 11 6 to clean out from the surface of the drum 100 and from the web 104 itself the narrow threads of paper, thereby leaving a plurality of spaced strips or bands 122. Channels 120 are thus defined between the strips 122. As seen in Figure 12, the brush assembly 124 comprises of a plurality of individual brush elements 126 which are each approximately the width of the channels 1 20 cut in the middle web 1 04. The brush assembly 124 is rotated clockwise at a greater speed than the drum 100 so that the cut paper threads will be thrown outwardly tangentially from the drum 100 and onto a carrier 128 which may be a conveyor to take the waste out of the room in which the machine is located.

A second paper web 1 30, which is to become one of the outer paper plys or layers of the improved paper structure, is fed from a roll 132 about idler rollers 134 and 136 to a gluing station 140 where adhesive is applied to one surface of the web 130 by means of rollers 142, 144. From there, the web 130 is fed about another idler roller 1 38 which maintains the desired tension on the web 1 30 and onto the heated drum 100 in overlying relationship over the middle paper layer 104 which, at this location, is comprised of a plurality of strips 122.

A pressure roller 146 is preferably provided with a rubber or similar face and is maintained in pressure contact with the drum 100 in order that pressure is applied to hold the two paper layers 104, 1 30 in adhesively sealing relationship and to avoid slippage therebetween. The laminate paper structure on drum 100 is then fed about the pressure roller 146 and passed through an oven 148 which is heated with hot air to evaporate the greatest part of the water or solvent remaining in the adhesive or in the paper laminate. The use of a heating oven is another arrangement for aiding in drying and/or curing of the adhesive, and in the embodiment shown in Figure 10, is in addition to heated drum 100.Further, it is to be noted that the oven 148 need not remove all of the moisture in the paper laminate as any excess moisture in the medium will evaporate in the heating ovens of the corrugating machine to be described hereinbelow.

From the oven 148, the laminated two layers 104, 1 30 are fed about a second heated drum 102 wherein individual wires 1 50 are fed from a spool arrangement 154 about a guide arrangement 1 52 precisely into the channels 1 20 provided between the strips 122 of the middle paper layer 1 04. This spool arrangement 1 54 and guide arrangement 1 52 are each similar to those described with respect to the apparatus of Figure 1 except that they are adapted to feed a pair of wires 1 50 into each of the channels 120.As best seen in Figure 16, the spooling arrangement 1 54 comprises a plurality of individual spools 1 56 mounted and keyed on a common cylinder 1 58. The individual spools 1 56 are each charged or loaded with a plurality of wires 1 50, in this instance 1 6. For 6.35 mm spacing between channels 120, the individual spools 1 56 would each be approximately 50.8 mm wide as two wires 1 50 are to be set in each channel 120. The guide arrangement 152, like the guide arrangement of Figure 1, comprises a guide roller with a plurality of spaced peripheral flanges 153.The spacing between the guide flanges 1 53 corresponds to the width of the channels 120 (i.e., twice the thickness of a wire 1 50) and the thickness of the flanges 1 53 corresponds to the width of the bands or strips 122.

A second overlying paper web 1 60 is fed from a roll 1 62 about idler rollers 1 64 and 1 66 to a gluing station 1 68 where adhesive is applied to one side by means of rollers 1 70, 1 71. The adhesively coated web 1 60 is then fed about idler rollers 1 72, 1 74 onto the heated drum 102 and into overlying relationship on the middle paper web 104 having the wires 1 50 placed therein to complete the wire reinforced laminated structure 1 80. The laminate of the three paper webs 1 04, 1 30 and 1 60 is then taken from the heated drum 102 about pressure roller 182.The pressure roller 182, like rollers 112, 146 is preferably provided with a rubber or similar face so that pressure can be applied against drum 102 to prevent slippage of the paper webs 104, 130 and 1 60 with respect to one another and with respect to drum 102.

From roller 182, the laminate 1 80 is passed through an oven 1 84 which serves the same function as oven 148 - namely, to evaporate the greatest part of the water or solvent remaining in the adhesive or in the paper laminate 180. The resulting laminate structure 1 80 is then passed about idler rollers 186, and 1 88 and fed onto a take-up drum 1 90.

As best seen in Figure 15, the resulting wire reinforced paper structure 180 is one in which pairs of wire reinforcing elements 1 50 are set in channels 120 formed in the middle paper web 104. The upper and lower outer plys or layers 130, 1 60 as well as the band 122 of the middle web 104 serve to completely enclose and entrap the wires 1 50 so that they are maintained in a relatively rigid position.

In the embodiments of the invention described in Figures 1-1 6, various types of adhesives may be employed depending on the characteristics desired in the completed product. On form of adhesive which has been found useful involves a mixture of vinyl and starch. Such a product is manufactured by National Starch and Chemical Corporation and comprises an aqueous solution containing VINAMYL, a chemical modification of starch, CROSREZ, a catalyst, and DURABOND, a chemically modified startch.

VINAMYL, CROSREZ and DURABOND are trademarks of the National Starch and Chemical Corporation and one composition may be formed as follows: Primary Mixer A Tap Water 378.6 liters (100 gals.) B Vinamyl 181.4 kg (400 Ibs.) C Heat to 54.40C (1300F) D Caustic Soda dissolved in 14.52 kg (32 Ibs.) 18.93 liters (5 gallons) of water E TapWater 378.6 liters (100 gals.) Secondary Mixer A Tap Water heated to 29.40C (850C) 1211.5 liters (320 gals.) B Crosrez 45.36 kg (100 Ibs.) C Borax (10 mol) 13.61 kg (30 Ibs.) D Durabond 635.0keg (1400 Ibs.) Then intermix the primary mix into the secondary mix.

The adhesive becomes highly resistant to water after being dried and cured and has the advantage that it will tend to swell during the curing process and thus will completely fill all interstices that may exist between the webs and the wire reinforcing elements disposed therebetween in the channels and firmly adhere the webs and wires together. Other types of adhesives may also be utilized such as the caseins, hot melts, such as mixture of resin and wax, and pressure sensitive adhesives which may also include additives to impart a thermosetting quality thereto.

Furthermore, according to another aspect of the present invention, water resistant compositions, such as for example, rubber latex compositions, may be used as the adhesive. This is particularly advantageous in that it affords a greatly simplified procedure for producing a waterproofed (as opposed to simply water resistant) cardboard structure. Presently, to produce a waterproofed structure, it is necessary to wax the cardboard or cover the interior of the cardboard with a polyurethane film.

However, these steps are not necessary if a rubber latex adhesive composition is utilized in producing the laminated paper structures in accordance with the present invention. Instead, by having three individual paper layers laminated together, the rubber latex composition applied between each of the paper layers is adhered, as at 1 93, 1 95 of Figure 1 7, on both sides of the middle paper layer. In this way, the rubber latex composition completely encloses the middle paper layer of a laminated paper structure with the exception of the exposed edges. The resulting paper laminate can then be completely waterproofed simply by taping the open edges of the laminate.Such a structure is shown in Figure 1 7 in which a wire reinforced laminate 192 having wires 1 94 disposed in channels in the middle paper layer has been taped about its edges with a water resistant tape 1 96. Water or other moisture will be unable to permeate through the rubber latex composition (or the tape on the edges) thereby insuring the integrity of the middle paper layer against the adverse effects of moisture. In this regard, it is to be noted that it is the middle paper layer which has the reinforcing wires therein. Thus, the structural strength of the wire reinforced paper laminate will be substantially maintained, as a result of the reinforcing wires, even if the outer paper layers of the laminate soften as a result of moisture.

Examples of rubber latex compositions which will afford these features in accordance with the present invention include the following: AMSCO RES 41 25 (a soft carboxylated styrenebutadiene copolymer having 49% solids); Basic Adhesives, Inc., BR-989 (a flexible resin-based adhesive), and Basic Adhesives, Inc., BL-986 (a latex-based adhesive). It is to be noted that with use of these rubber latex compositions, a heated roller or oven for setting/drying is optional as these rubber latex compositions are all water emulsions. In other words, they do not require heating for setting. However, use of a heated roller or oven will result in drying of the adhesives more quickly. Water resistant tapes for taping the edges of the paper laminate are well known. For example, paper type tapes which could be utilized include Scotch Brand 21 7 and Scotch Brand 260.Further, plastic type tape of mylar or acetate could be utilized as well as tapes of other types of suitable plastic. These plastic type tapes may or may not be filament reinforced.

Wire thickness, of course, may very depending on the structural strength required. It has generally been found that wire elements 52 or 150 of the order of 0.127--0.635 mm (i.e., 5-25 mils) and more particularly on the order of 0.254-0.381 mm in diameter are most effective. Various thicknesses of paper webs may be used, though generally it is not necessary to exceed a 11.8 kgf (i.e. 26 pound) paper in order to achieve an extremely high degree of strength with wire thicknesses as small as 0.127 mm. It is obvious, however, that when extremely light board is required, lighter paper and thinner wire can be utilized.

As previously mentioned, the spacing between the wire elements 52 or 1 50 in the middle layer of web of paper may be almost any desired spacing, but is preferably on the order of from 3.175 to 12.7 mm (i.e., 1/8 to 1/2 inch). In the embodiments shown in Figures 1-16, 6.35 mm spacing has been used and wire thicknesses of 0.254 mm has been shown.

As noted previously, the wire reinforced paper structure wound up on the take-up rolls 84 or 1 90 may be used for any desired purpose where increased structural strength of a paper product is desired.

In particular, this wire reinforced paper laminate is especially useful in producing corrugated board of the type in which the facings or liners are adhered to the crest portions of each side of the corrugated medium. Figure 18 illustrates an embodiment of the invention for forming such corrugated board which is generally known as double-faced corrugated board. For purposes of illustration, this embodiment of the invention utilizes only a single wire 52 in each of the channels 31 formed in the middle layer 30 of the wire reinforced laminate according to the present invention. However, it is to be understood that arrangements of double wire or even a greater number of wires may be utilized in order to obtain a desired strength and rigidity of the resultant corrugated board.Further, it is to be noted that the wire reinforced paper laminate of the present invention can be used as the outer facings or liners of the double-faced corrugated board if desired. However, in many applications, it has been found that merely providing adequate reinforcement of the corrugated medium will provide the desired degree of rigidity, while in other applications where a higher degree of rigidity is desired, all three layers need to be reinforced with wires.

More specifically, and with reference to Figure 1 8, a reinforced laminate 200, such as one of the laminates produced by the structure shown in Figure 1, is fed from a roll 202 about a pair of corrugating rollers 204 and 206. The corrugating rollers 204 and 206 are standard corrugating rollers which serve to corrugate the wire reinforced laminate 200 transversely of the plurality of wires 52 in the channels 31. An adhesive is applied to the corrugated laminate by a roller 208 immersed in an adhesive filled trough 210. A second paper layer 212, which in the embodiment shown in Figure 18 merely comprises a paper web, is fed from a roll 214 and about a roller 216 which bears against the corrugating roller 206 and in so doing produces a structure such as shown in Figure 19.It will be observed that this structure shown in Figure 1 9 is greatly enlarged for purposes of clarification. The corrugated structure or medium 200 with the paper layer 212 applied to the crest portions of one side thereof then passes about roller 21 8 whereupon it is fed through a suitable oven 220 to evaporate the liquid and cure the adhesive.

The corrugated structure 200 with the layer 212 applied to one side thereof is then fed about the roller 224 to the adhesive applying station 226 consisting of a roller 228 and an adhesive applying roller 230, the latter being immersed in an adhesive containing trough 232. This adhesive applying station 226 applies adhesive to the crest portions of the other side of the corrugated laminate structure 200.

A third paper layer 234, which in the embodiment shown is identical to the lower layer or web 212, is fed from a roll 236 and about rollers 238 and 240, the latter being in contact with the corrugated layer or medium 200 as it immerges from the adhesive applying station 226. A back-up roller 242 cooperates with the roller 240 to insure firm contact of the layer or web 234 with the corrugated layer 200. The resultant 250 comprising the corrugated medium 200 with upper and lower facings or liners 212, 234 on each side thereof then passes through a second oven 244 to evaporate liquid and cure the adhesive applied at the adhesive applying station 226. The resulting structure 250 is shown in cross-section in Figure 20 which has been greatly enlarged for purposes of clarification.

As seen in Figures 20 and 21, the corrugated medium 200 of the corrugated board 250 is a laminate structure according to the present invention comprised of three layers of paper 12, 30, 66 with wires 52 set in trenches or channels 31 in the middle layer 30. In the particular embodiment shown in Figures 20 and 21, each of the three paper layers 12,30,66 forming the laminate structure is 0.254 mm in thickness, as is the wires 52 set in the channels 31. The upper and lower facings or liners 212,234 are simply paper webs in the shown embodiment which are each of 0.508 mm in thickness.

It is to be noted that with a 6.35 mm spacing between the wires 52 in the corrugating medium 200 of the board 250, and with the use of standard corrugating rollers 204, 206 to produce the corrugations in which there are approximately 5 steel arches per 25.4 mm of length, there are over 3,000 steel arches in 929 square centimeters (i.e., one square foot) of corrugated board.

Figures 22 and 24 show an alternative form of double-faced corrugated board 260 in which a wire reinforced laminate similar to laminate 90, is used for both the top and bottom liners orfacings262, 264 adhered to the crest portions of each side of the corrugating medium 200. Thus, there are three wire reinforced laminate webs making up the structure shown in Figures 22 and 24.

Figure 23 shows another alternative form and use of the wire reinforced laminate structure in that a 0.508 mm thick paper web 266 is used as a corrugating medium of a double face corrugated board 270, and wire reinforced laminates, similar to laminate 90, form the upper and lower facings 272, 276.

While such an arrangement does not produce the strength of the boards 250 or 260, in which the wires 274, 278 are used for the corrugating medium 200, the board 270 shown in Figure 23 does produce an increase in structural strength for the corrugated board.

It will be noted with reference to Figure 23 that the wire reinforcing elements 274 in the upper facing 272 have been laterally or transversely off-set with respect to the wire reinforcing elements 278 in the lower facing 274. This is advantageous to provide an increased strength for the resulting doublefaced wire reinforced corrugated board 270 since it does not permit a puncturing element to pass cleanly therethrough between wire reinforcing elements 274, 278. In essence, by laterally off-setting the wires such that the wire elements 278 of the lower facing 276 lie directly beneath the mid-point between the wire reinforcing elements 274 of the upper facing 272, an equivalent spacing which is one-half the actual spacing of the wires is achieved for the board 270.That is, if each of the wires in both the upper and lower facings 272,276 is spaced 6.35 mm from one another, then by off-setting the wires in the two facings 272, 276 so that the wires 278 of the lower facing 276 lie below and halfway between the wires 274 of the upper facing 272, an equivalent spacing of 3.1 75 mm for wire reinforcing elements 274, 278 is achieved. It is to be noted that this same principle can also be applied with respect to the wire reinforcing elements of the corrugated medium where the corrugated medium is also wire reinforced.

To provide even further increased strength for a double-faced corrugated board, and in particular to increase the structural strength of the outer facings or linings of the board, two sections of wire reinforced paper laminate, each produced in accordance with the present invention, can be laminated together so that the wire reinforcing elements of each of the two laminates are disposed perpendicularly to one another. That is, sections of wire reinforced laminate can in turn be laminated in series to a second wire reinforced laminate web so that one set of wire reinforcing elements is disposed transversely of the other set of wire reinforcing elements. In a sense, this forms a type of off-set wire mesh or grill, in the form of a grid, for the resulting laminate.As can be appreciated, the second set of reinforcing wires, transverse to the first set of wires, serves to increase the structural strength of the resulting grid type laminate.

Referring now Figures 25 and 26, there is disclosed apparatus for producing such a grid type reinforced paper laminate in which the wire reinforced elements are disposed both transversely and longitudinally with respect to the resulting laminate web. Initially, wire reinforced laminate 300, such as, for example that produced in accordance with Figures 1-8, is fed from a drum 300 about roller 302 to a web length and tension compensator generally denoted by the numeral 304. The compensator 304 includes a roller 306 about which the web 300 passes, a dancer roller 308 which is arranged to move vertically, and a cutter roller 310. A pressure roller 312 bears against the cutter roller 310 to maintain the web 300 in contact at all times with the cutter roller 310. A cutter blade 314 is periodically reciprocated to sever the web 300 in precise lengths.In the instant embodiment of the invention, the web 300 with the wires 320 disposed in the channels in the middle paper layer is severed into lengths equivalent to the width of the web 300 and each severed length is guided downwardly by a chute 324 onto a belt 326 carried by roller 328. It will be noted that since the wire elements 320 are firmly held in place in the channels a clean cut will be obtained without any substantial tearing or ripping of the paper layers or exposure of the wire elements. The speed of the belt 326 and the speed at which the web 300 is transported are coordinated so that each severed web section 330 is positioned on the belt 326 in substantially contiguous relationship with the previous web section. To achieve this end, additional feed rollers may be employed if desired in order to insure proper movement of each severed web section 330 onto the belt 326.If desired, the severed web sections 330 may also be stacked for processing at a later time.

Referring now to Figure 26, it can be seen that the cut-off roller 310 and the chute 324 are illustrated in elevation and that the belt 326 is carried by rollers 328, 329. It will be observed that each of the severed sections 330 is now positioned in contiguous relationship with the preceding section on the belt 326 and the wires 320 held in the channels in the middie layer are now disposed in transverse relationship with reference to the direction of the motion of the belt 326 and, thus, the severed sections 330. A second wire reinforced laminate web 340, again such as may have been produced in accordance with Figures 1-8, is fed from a drum 342 downwardly and about a pressure roll 344 which urges it against the severed sections 330 having the wire reinforcing elements thereof transversely disposed.A coating of adhesive is preferably applied to one side of the laminated web 340 by means of rollers 346, 348 and 350, the latter being partially immersed in a trough 352 containing an adhesive. A pan 357 is preferably disposed below the adhesive applying means in order to prevent adhesive from accidentally dripping upon the severed sections 330. The resulting laminate 360, consisting of a first laminate 330 having traverseiy disposed wires held in channels therein and a second laminate web 340 having longitudinally disposed wires in channels therein, is then fed about the roller 362 having a cooperating pressure roller 364. The pressure roller 364 has a resilient surface in order to urge the unsevered paper laminate 340 into firm contact with the severed sections 330 to firmly set and adhere the two wire reinforced paper laminate sections together.The completed laminate 360 then passes about rollers 366, 368, 370 and is wound up on a spool 372.

The adhesive utilized for adhering the second wire reinforced paper web 340 to the severed sections 330 of the wire reinforced paper laminate may be of any desired composition, for example, any of the adhesives mentioned hereinabove at pages 21-24. Normally, an adhesive is utilized which can be cured rapidly in the presence of heat and under those conditions it may be desirable to heat the roller 362 in order to rapidly cure the adhesive. In that instance, the rollers 366 and 368 may then be in the form of cooling rollers in order to bring the laminate to approximately room temperature prior to rolling onto the spool 372. Alternatively, if a rubber latex adhesive compound is utilized to produce a waterproofed paper laminate, as noted above, heating of the roller 362 is not required for curing of the adhesive, but instead merely speeds up the drying process.It will also be understood that inasmuch as the severed sections 330 are placed on the belt 326 in contiguous relationship, it is not necessary to attach the sections 330 one to the other since they will automatically be adhered to the web 340, thus forming a continuous and substantially uninterrupted layer. Further, as can be appreciated, other methods for adhering sections of laminate transversely to a second laminate web may be utilized.

The resultant grid type laminate 360 having a first laminate with wire reinforcing elements being longitudinally disposed and a second layer with wire reinforcing elements transversely disposed can be seen in cross section in Figure 27. As can be seen, the top layer (the laminate web 340) comprises a laminate of three paper sections 374,376,378 in which channels 382 are formed in the middle section 376 and into which channels 382 wire reinforcing elements 380 are disposed between the upper and lower paper sections 374, 378. This upper laminate 340 is adhesively secured to a second layer (the laminate sections 330), also comprised of three paper sections 384, 386, 388 adhesively secured together.Again, the middle layer 386 is provided with a series of channels into which wire reinforcing elements 320 are disposed. But in this instance, the elements 320 are disposed transversely of the wire reinforcing elements 380 of the upper laminate 340.

By having both transversely disposed and longitudinally disposed wire reinforcing elements, an extra dimension of strength is added to the resulting paper laminate 360. In essence, the resulting laminate 360 forms an offset grid type structure in which only small, square-shaped areas of unreinforced paper exists, thus making for a stronger structure which will not puncture as easily. Such a grid type laminate 360 is particularly useful as the outer facings or linings of double-faced wire reinforced corrugated cardboard. Thus, the resulting laminate 360 can be adhered, for example, with the apparatus as shown in Figure 1 8, to each side of the crest portions of a wire reinforced corrugated medium.That is, referring to Figure 18, the resulting grid type laminate 360 may be substituted for either or both of the laminates fed from spools 214, 236. Such a double-faced corrugated cardboard structure in which a grid type laminate is used for both of the outer facings is shown in Figure 28. There, it is seen that the double-faced corrugated cardboard 400 comprises a corrugated medium 402 having wire reinforcing elements 404 disposed transversely of the corrugations, and two outer facings 406, 408 adhered to the crest portions of the corrugated medium 402. Each of these outer facings 406, 408 is comprised of a grid type laminate, one laminate 410 of which has wires 412 longitudinally disposed and the other laminate 414 of which has wires 416 transversely disposed.

As noted hereinabove, the use of a middle layer of paper which is notched or cut to produce a series of channels therein for wire reinforcing elements serves as a convenient spacing and holding medium and results in an improved wire reinforced laminate structure. In this regard, it will be appreciated that even though the cross-sectional area of the channels is greater than the crosssectional area of the wires disposed therein, the width and depth of the channels substantially correspond to the dimensions of the wires disposed therein, though this is not as critical for the width, so that the wires are rigidly held in place and the outer facings are relatively smooth. This is advantageous as it will not greatly wear corrugating rollers or interfere with cutting operations. Further, adhesion of the various layers of paper is improved as well as adherence to other materials.

It is also contemplated that the channels may be formed by extruding parallel thermoplastic strips onto a layer of paper, the thermoplastic strips serving the same purpose as the illustrated paper strips.

However, the plastic strips could provide the additional advantage that adhesive layers would not be required if the plastic itself adheres to the paper layers. Also, the characteristics of the plastic strips could be varied by the use of different fillers.

It is also contemplated that a thermoplastic material could be extruded over a paper layer having a plurality of parallel metal wires disposed thereon so that the wires, in effect, define their own channels and are tightly held therein upon solidification of the plastic material. The height of the plastic material would at least be equal to the height of the wires. A second paper layer could be adhesively secured to such plastic material while it is still tacky.

It will be appreciated from the above discussion that while only certain forms of the invention have been illustrated and described, it is understood that modification, changes and alterations may be made without departing from the spirit and scope thereof as defined by the appended claims.

Claims

1. A wire reinforced paper structure comprising first and second paper layers adhesively secured together, spaced parallel channels disposed between said paper layers, and a plurality of longitudinally extending spaced parallel metal wires disposed in said channels, the depth of said channels substantially corresponding to the height of the wires disposed therein and the width of each of said channels being at least equal to the total width of the wires disposed therein, whereby the wires are firmly held in said channels so that exposing of the wires upon cutting of said reinforced paper structure is inhibited.

2. The wire reinforced paper structure of Claim 1, wherein said first paper layer comprises a paper web having a plurality of paper strips adhesively secured to said paper web, said paper strips being parallel to one another and spaced so that the spacing between said strips defines the width of said channels, and the opposed surfaces of said first and second paper layers defines the height of said channels, said second paper layer being adhesively secured to said plurality of spaced strips.

3. The wire reinforced paper structure of Claim 1 or 2, wherein said wire reinforced paper structure is a corrugated wire reinforced paper structure which is corrugated transversely of said longitudinally extending wires.

4. The wire reinforced paper structure of Claim 1, wherein said wire reinforced paper structure is a corrugated board comprising at least one liner and a corrugated medium, said liner being adhesively secured to the crests of one side of the corrugated medium, and said first paper layer is a portion of one of said at least one liner and said corrugated medium, said channels being formed in said first paper layer.

5. The wire reinforced paper structure of Claim 4, wherein said wires are disposed in said channels in both said at least one liner and said corrugated medium.

6. The wire reinforced paper structure of Claim 1 , wherein said wire reinforced paper structure is a corrugated board comprising a corrugated medium and first and second liner mediums, said first liner medium being adhered to the crests of one side of said corrugated medium and said second liner medium being adhered to the crests of the other side of said corrugated medium, and said wires are disposed in channels in at least two of said mediums.

7. The wire reinforced paper structure of Claim 6, wherein said wires are disposed in channels in all of said mediums.

8. The wire reinforced paper structure of Claim 6, wherein the longitudinally extending wires in said channels of one of said two mediums are laterally offset with respect to said longitudinally extending wires in said channels in the other of said two mediums.

9. The wire reinforced paper structure of Claim 1, wherein said wire reinforced paper structure is a corrugated board comprising a corrugated medium and a pair of liner mediums, one of said liner mediums being adhered to the crests of one side of said corrugated medium and the other of said liner mediums being adhered to the crests of the other side of said corrugated medium, said one of said liner mediums comprising first and second reinforced paper laminates laminated together, and said wires being disposed in channels of each of said first and second reinforced paper laminates with said wires in said first reinforced paper laminate extending in a first direction and said wires in said second reinforced paper laminate extending in a second direction, said second direction being substantially perpendicular to said first direction.

10. The wire reinforced paper structure of Claim 1, wherein said wire reinforced paper structure includes first and second reinforced paper laminates laminated together, said wires being disposed in channels in each of said first and second reinforced paper laminates with said wires in said first reinforced paper laminate extending in a first direction and said wires in said second reinforced paper laminate extending in a second direction, said second direction being substantially perpendicular to said first direction.

11. The wire reinforced paper structure of any one of the preceding claims, wherein more than one metal wire is disposed in at least some of said channels.

12. The wire reinforced paper structure of any one of the preceding claims, wherein said longitudinal wires have a thickness ranging between 0.254 and 0.381 mm.

13. A wire reinforced paper structure substantially as described and shown in the accompanying drawings.