Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/04—Interconnection of layers
  • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B29/00—Layered products comprising a layer of paper or cardboard
  • B32B29/002—Layered products comprising a layer of paper or cardboard as the main or only constituent of a layer, which is next to another layer of the same or of a different material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
  • B32B37/12—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives
  • B32B37/1284—Application of adhesive
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B38/00—Ancillary operations in connection with laminating processes
  • B32B38/14—Printing or colouring
  • B32B38/145—Printing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2250/00—Layers arrangement
  • B32B2250/26—All layers being made of paper or paperboard
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/402—Coloured
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2317/00—Animal or vegetable based
  • B32B2317/12—Paper, e.g. cardboard

Definitions

• Our invention relates to the manufacture of continuous- sheet, adhesively bonded paper laminates of three or more plies made by using a controlled adhesive strike-through technigue, in which multiple junctures between plies are attained using a single application of adhesive.
• the multi-ply laminates of our invention are especially suited for color-printed paper- products such as disposable table napkins, since our laminates can be color-printed to their edges without the loss of registration that ordinarily accompanies edge embossing.
• Prior art attempts to address these problems have used adhesive to bond the plies together, thus reducing or eliminating the need for edge embossing. But such prior art processes have reguired multiple adhesive applicator stations, typically one such station for each boundary between plies. Thus, for example, a three-ply laminate reguired two applications of adhesive. Moreover, where adhesive was applied between plies by spraying, much more adhesive than necessary was used to stick the plies together.
• multi-ply laminates can be made using a novel process that relies on controlled strike-through of adhesive from one surface of a carrier sheet to the other. This permits one or more additional plies to adhere to the side of the carrier sheet opposite that to which adhesive was applied.
• three or more plies can be joined with only one application of adhesive. It is unnecessary to apply any heat to ensure proper adhesive strike- through.
• napkins made from the our laminate can be printed out to their edges without loss of color registration and with about 25% less waste than is ordinarily experienced in converting non-adhered three ply laminate to paper napkins via edge embossing.
• a flexographic impression process is used to apply adhesive to the carrier sheet.
• a three-ply laminate using plies having a basis weight of about 9.7 lbs per 3000 ft 2 , we achieved very acceptable peel strengths between all three plies at polyvinyl alcohol adhesive coverage levels of only 1% to 2% of the paper surface. Only one adhesive application was used to adhere all three plies together.
• Other embodiments of our invention include a variety of processes using alternate adhesive application techniques, while still achieving controlled adhesive strike-through. Although the manufacture of paper napkin feedstock is an important application of our invention, there are other uses too.
• one ply may be a liguid-impermeable plastic sheet; reinforced laminates in which the carrier sheet is selected from one of a number of strong synthetics; paper/metal laminates such as chewing gum wrappers; and quilted laminates including one or more very high-bulk layers. It is an object of this invention, therefore, to provide multi-ply paper laminates by applying only one adhesive layer to achieve two or more junctures between sheets.
• Figure 1 is a drawing of a three-ply laminate made using the process of this invention, showing the two outer plies being peeled back from the central carrier sheet.
• Figure 2 is a schematic showing a flexographic printer setup that has been specially modified to make a three-ply laminate using our invention.
• Figure 3 shows a flexographic plate roller equipped with a rubber mat of one design that we have found suitable for practicing our invention.
• Figure 4 is a schematic showing an alternate, special flexographic printer setup that can be used to make a five-ply laminate using our invention.
• Figure 5 is a schematic of a rotogravure-type press specially modified to practice our invention.
• Figure 6 is a schematic of a press in which a special pressurized roller is used to practice our invention.
• Figure 7 shows one possible pressurized adhesive feed arrangement for the roller of Figure 6.
• Figure 8 is a schematic of an alternate process for practicing our invention using sprayed-on lines of adhesive.
• Figure 9 shows an adhesive sprayer for applying parallel lines of adhesive.
• Figure 10 is a schematic of another alternate process for practicing our invention using a hot-melt adhesive.
• Figure 11 illustrates a laminate made using controlled strike-through in which the characteristics of the plies are chosen to allow several adhesive patterns to be created on one side of the carrier sheet.
• Figure 12 shows a quilted laminate made using a high-loft carrier sheet.
• Figure 13 shows one rubber mat pattern suitable for producing the guilted laminate of Figure 12.
• FIG. 1 the structure of a three- ply laminate made according to this invention comprises a carrier sheet 1, a second ply 2, and a third ply 3.
• the second and third plies are shown being peeled away from the carrier sheet.
• Figure 2 illustrates a preferred embodiment of our invention, using a flexographic press to apply the adhesive.
• Carrier sheet 1 and third ply 3 are spooled together on unwinder 9. They are unwound from unwinder 9, around tension roller 18 and from there to the nip 16 between plate roller 11 and impression roller 4.
• Adhesive 6 is applied to one surface of carrier sheet 1 from textured rubber mat 15 on the exterior of plate roll 11. At the nip 16, controlled strike-through of the initial adhesive pattern 6 begins. Carrier sheet 1 and third ply 3 travel further around impression roller 4 to bottom calendar roll 5. At that point, first ply 3 (which is unwound from unwinder 13 and fed past tension roller 19) is pressed against adhesive pattern 6 at nip 17. The high pressure exerted between bottom calendar roll 5 and impression roll 11 completes the operation of forcing adhesive through carrier sheet 1 to form struck-through adhesive pattern 7. From nip 17 the finished three-ply laminate proceeds to rewind 14, onto which the completed roll is wound.
• adhesive is applied to anilox roll 10 by means of a reverse angle double doctor blade system 12.
• Anilox roll 10 transfers the adhesive to the raised pattern on rubber mat 15 just as ink is applied in an ordinary flexographic printing operation.
• anilox roll 10 may revolve against a fountain roll (not shown) , which in turn picks up adhesive from a feed trough (also not shown) .
• one suitable pattern for rubber mat 15 is one utilizing 1/32 inch dots in a diamond-shaped pattern on 0.265 inch and 0.370 inch centers. See Figure 3. This pattern provides approximately one percent area coverage, which we have found is more than sufficient for a three-ply product. Another suitable pattern uses 1/16 inch dots and provides an area coverage of 3.1%. Generally, larger dots provide increased adhesive penetration and are especially suited for use with low airflow papers.
• Preferred sheet speed for this embodiment is between 50 to 3000 fpm, with the most preferred range being 530 to 2500 fpm. At the lowest speeds the adhesive tends to set between the point of application of adhesive to the rubber mat 15 and the transfer of the adhesive to the carrier sheet l at nip 16, causing some buildup of fiber on the rubber mat 15.
• the upper sheet speed limit depends primarily upon eguip ent capabilities.
• the suitable amount of "squeeze,” or interference, at nip 16, where adhesive is applied, is between 0.002 inch to 0.003 inch.
• High pressures should be used between the impression roller 4 and the bottom calendar roll 5, to facilitate strike- through. We find that pressures up to about 300 lbs per linear inch (pli) , or more, are suitable. Pressures above 50 pli and below 300 pli are especially preferred.
• FIG 4 illustrates an embodiment of our invention making a five-ply laminated product. This can be accomplished by adding an additional unwinder 20 on which a second carrier sheet 21 and a fifth ply 22 are spooled. Adhesive is applied to second carrier sheet 21 by a second plate roll 26 bearing another rubber mat 27, which in turn is fed by a second anilox roll 25 and by another reverse angle double doctor blade 24. Three-ply laminate can be fed directly to the nip between second impression roll 28 and second bottom calendar roll 31 from an initial production operation of the sort shown in Figure 2. The finished five-ply product is then spooled on winder 32.
• a laminated product having five or more plies can be made in two passes through the equipment shown schematically in Figure 2.
• three-ply laminate made in an initial pass is spooled off of unwinder 13, with two additional plies added from unwinder 9.
• the operation of our process is otherwise similar to that described above. It will be understood by those of ordinary skill that laminates having even numbers of plies also can be created using the process of our invention, simply by using a step in which only one additional ply, instead of two, is added. All such variations are within the scope of our invention, which we intend to limit only as set forth in our claims.
• FIG 5 we show another embodiment of our invention in which the flexographic adhesive application method using an anilox roll and a rubber mat is replaced by a an engraved roll 40 turning against a flat roll 41, an arrangement similar to a rotogravure press.
• Adhesive pattern 46 is applied to carrier sheet 38 from reservoir 39 via the pattern on engraved roll 40.
• Carrier sheet 38 and third ply 37 are fed from unwinder 36.
• First ply 44 is fed off of unwinder 43 and meets the carrier sheet at the nip between flat roll 41 and flat roll 42. This creates adhesive pattern 47 between carrier sheet 38 and third sheet 3, as in the embodiment of Figure 2.
• Figure 6 illustrates yet another embodiment, in which adhesive is pumped from reservoir 49 by pump 50 to a plurality of holes 52 in the periphery of a perforated drum 48.
• the periphery of drum 48 rotates against impression roll 4.
• Figure 7 shows a detail of one possible feed system for perforated drum 48.
• adhesive feed pipe 53 terminates at plenum 54 on one end of drum 48.
• Feed holes 55 drilled in the periphery of drum 48 and parallel to the axis of drum 48 contact plenum 54, which remains immobile as drum 48 rotates.
• Adhesive then moves through feed holes 55 and out perforations 52, thus producing a dot or other desired pattern of adhesives on the carrier sheet.
• FIGS 8 and 9 illustrate yet another possible adhesive feed arrangement.
• adhesive is pumped under pressure into feed line 56, from which it sprays in a series of jets 58 from a plurality of holes 59 onto carrier sheet 1.
• the result is parallel lines of adhesive along the length of the roll of laminate. This embodiment eliminates need for any system of adhesive feed rolls.
• Figure 10 illustrates yet another embodiment of our invention, utilizing a hot melt adhesive.
• a two-ply roll comprising carrier sheet 67, third ply 68 and hot melt adhesive pattern 66 (which can be applied by a variety of techniques known in the art) is first spooled onto unwinder 60.
• the two-ply roll, with the two plies as yet unattached to each other, is spooled off of unwinder 60 and between heated roll 65 and pressure roll 72 (which also may be heated, if desired) .
• first ply 69 is fed from unwinder
• FIG. 1 The simplest three-ply laminate that can be produced using our invention is shown in Figure 1.
• adhesive pattern 6 is applied to one surface of carrier sheet 1, and our process causes that pattern to strike through the carrier sheet creating adhesive pattern 7 on the opposite surface.
• the characteristics of carrier sheet 1 are chosen to facilitate adhesive strike through; the characteristics of first ply 2 and third ply 3 are chosen to minimize or prevent adhesive striking through those plies.
• carrier sheet 1 is chosen to have a very open structure (using the criteria outlined below) ; first ply 2 is selected for a much less open structure as is fourth ply 73.
• Third ply 3 is chosen to have an open structure like carrier ply 1, thus allowing adhesive to strike through third ply 3 as well as through carrier ply l. This creates adhesive pattern 72 between third ply 3 and fourth ply 73, while preventing strike-through of adhesive past first ply 2 or fourth ply 73.
• not all plies need be made of paper.
• one or more of the exterior plies can be flexible metallized sheets, as in chewing gum wrappers.
• the carrier sheet may be a synthetic spunbond having suitable air flow characteristics.
• Such a carrier sheet adds strength to the laminate.
• Plies of variable strength also can be used to make such items as microwaveable popcorn bags.
• sheets and adhesive are selected to provide strength while retaining ability to release moisture during popping.
• Figure 12 Another structure that can be made using our invention is shown in Figure 12.
• rubber mat 15 is patterned with a diamond-shaped criss-cross pattern of raised lines 78 as shown in Figure 13, in order to lay down a diamond- shaped or quilted adhesive pattern 75.
• That pattern is applied to a high-loft or highly creped carrier sheet 74, which is spooled on an unwinder together with a much tighter third ply 76.
• a first, much tighter ply 77 is provided on a separate unwinder.
• the process embodiment illustrated in Figure 2 may be applied, causing the adhesive pattern 75 to strike through the high-loft carrier sheet 74 and create a corresponding diamond-shaped adhesive pattern 78 holding the high-loft carrier sheet to third ply 76.
• the result is a sealed paper sheet having excellent insulating properties due to its high loft, but with stronger and tighter exterior plies.
• Such a laminate is ideal for disposable hospital gowns.
• the exterior plies can be made of water-resistant synthetics to create a laminate that also sheds water.
• One use for that laminate is for disposable table covers. The following table shows a selection of paper types that are suitable for use in various embodiments of our invention.
• the exterior plies can be made of water-resistant synthetics to create a laminate that also sheds water.
• One use for that laminate is for disposable table covers.
• the following table shows a selection of paper types that are suitable for use in various embodiments of our invention.
• the natural paper types are arranged in order of descending openness, as shown primarily by airflow.
• Airflow is measured in cubic feet per minute (CFM) over one square foot of fabric at a pressure drop of 0.50 inches of water.
• CFM cubic feet per minute
• Both of the synthetic spunbonds shown are suitable for use as carrier sheets.
• a less open paper is desired.
• Neither of the synthetic spunbonds shown in the foregoing table would be suitable as exterior plies.
• a wide range of adhesives can be used in our invention, providing that care is taken to match the viscosity and other properties of the adhesive, as applied, with the openness of the carrier sheet chosen.
• the following types of adhesives may be employed: silicates (especially sodium silicate) ; animal glue; fish glue; casein glue; soybean glue; starch-based adhesives; borated dextrin such as National Starch and Chemical Company's 13-1200 and 13-1558; polyvinyl alcohols such as National Starch and Chemical Company's 18-1535; ethylene vinyl acetates and cellulose adhesives.
• a third category of adhesives is the thermoplastic rubber adhesives of the A-B-A block copolymer variety.
• PVA polyvinyl alcohol
• Adhesive No. 18-1535 manufactured by the National Starch and Chemical Company of Bridgewater, New Jersey provides a suitable base for making down the adhesive used in our process.
• This adhesive can be used full strength, at a viscosity of approximately 2500 centipoise for use at 3.1% coverage from 1/16 inch dots with a natural carrier sheet having a basis weight of 9.7 lbs/3000 ft 2 and an airflow of approximately 120 to 140 CFM.
• Another suitable adhesive is CYCLOFLEX ⁇ L33-9600, also available from National Starch and Chemical Company.
• this starch-based adhesive can be used in the range of 50 to 700 centipoise viscosity, although better performance is attained near the lower end of this range.
• the viscosity range of 50 to 200 centipoise is especially preferred with this adhesive.
• adhesive viscosities in the range of 50 to 5000 centipoise can be used if appropriate paper types are selected.
• one very important goal is to provide laminates that not only possess sufficient peel strength between each ply to hold the plies together, but also for most applications to match the peel strengths so as to avoid very large differences in peel strength between various plies. This prevents preferential delamination of one ply from others, which in most instances is undesirable. More specifically, we have found that the ratio of the lowest mean peel strength to the highest mean peel strength should exceed 20% for best results.
• Peel strength can be measured using a variety of equipment. We prefer to measure 180° peel strength using a Thwing-Albert Model 225-1 friction/peel tester, manufactured by the Thwing-Albert Instrument Company of Philadelphia, Pennsylvania. We use a three inch wide strip of laminate, since variability tends to increase if thinner strips are tested. In the examples which follow, we conducted the tests at a separation rate of 15 inches per minute for a 20 second time period, measuring both peak and mean peel strengths in grams per 3 inch width.
• peel strength measurements were made on two commercially available 10 lb/3000 ft 2 three-ply laminates manufactured by Lincoln Pulp and Paper Co. of Lincoln, Maine.
• the Lincoln laminates had been converted to napkins, one having a tulip pattern and a heavy yellow color and the other having a rose pattern and a heavy pink color.
• Three peel strength tests were run on each of the two junctures between layers. The tests denoted “T” measured the peel strength between the middle sheet and the top ply, while the tests denoted "B” measured the peel strength of the adhesive layer between the middle sheet and the bottom sheet.
• the Lincoln three-ply laminate exhibited mean peel strengths between about 3.3 to 5.5 gr/3 inches, a level generally considered adequate for commercial uses such as novelty paper napkins.
• a carrier sheet with a lower airflow it is usually necessary to reduce the viscosity of the adhesive; to increase the adhesive area coverage or the size of the adhesive dots used in order to ensure adequate strike-through.
• a low airflow preferably below 50 CFM
• the adhesive set time must be such that setting does not occur between the adhesive application point and the nip above the bottom calendar roll. For most applications, adhesive coverages above 0.5% are adequate, and the pattern of the rubber mat should be selected accordingly.

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• Laminated Bodies (AREA)
• Paper (AREA)
• Adhesives Or Adhesive Processes (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=23533235

Family Applications (1)

Country Status (7)

Cited By (12)

Families Citing this family (1)

Citations (3)

Family Cites Families (3)

• 1996
  • 1996-02-09 EP EP96905446A patent/EP0755326A4/en not_active Withdrawn
  • 1996-02-09 CN CN96190270A patent/CN1150405A/zh active Pending
  • 1996-02-09 BR BR9605803A patent/BR9605803A/pt not_active Application Discontinuation
  • 1996-02-09 CA CA002187430A patent/CA2187430A1/en not_active Abandoned
  • 1996-02-09 WO PCT/US1996/001812 patent/WO1996024485A1/en not_active Application Discontinuation
  • 1996-02-09 AU AU49203/96A patent/AU4920396A/en not_active Abandoned
  • 1996-10-09 SE SE9603693A patent/SE507002C2/sv not_active IP Right Cessation

Patent Citations (3)

Non-Patent Citations (1)

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