Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/80—Paper comprising more than one coating
  • D21H19/82—Paper comprising more than one coating superposed
  • D21H19/822—Paper comprising more than one coating superposed two superposed coatings, both being pigmented
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D3/00—Rigid or semi-rigid containers having bodies or peripheral walls of curved or partially-curved cross-section made by winding or bending paper without folding along defined lines
  • B65D3/02—Rigid or semi-rigid containers having bodies or peripheral walls of curved or partially-curved cross-section made by winding or bending paper without folding along defined lines characterised by shape
  • B65D3/06—Rigid or semi-rigid containers having bodies or peripheral walls of curved or partially-curved cross-section made by winding or bending paper without folding along defined lines characterised by shape essentially conical or frusto-conical
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D3/00—Rigid or semi-rigid containers having bodies or peripheral walls of curved or partially-curved cross-section made by winding or bending paper without folding along defined lines
  • B65D3/10—Rigid or semi-rigid containers having bodies or peripheral walls of curved or partially-curved cross-section made by winding or bending paper without folding along defined lines characterised by form of integral or permanently secured end closure
  • B65D3/12—Flanged discs permanently secured, e.g. by adhesives or by heat-sealing
  • B65D3/14—Discs fitting within container end and secured by bending, rolling, or folding operations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
  • B65D65/38—Packaging materials of special type or form
  • B65D65/42—Applications of coated or impregnated materials
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/02—Chemical or chemomechanical or chemothermomechanical pulp
  • D21H11/04—Kraft or sulfate pulp
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
  • D21H19/385—Oxides, hydroxides or carbonates
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/56—Macromolecular organic compounds or oligomers thereof obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/58—Polymers or oligomers of diolefins, aromatic vinyl monomers or unsaturated acids or derivatives thereof
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/66—Coatings characterised by a special visual effect, e.g. patterned, textured
  • D21H19/68—Coatings characterised by a special visual effect, e.g. patterned, textured uneven, broken, discontinuous
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/10—Packing paper

Definitions

• This application is directed to paperboard structures and, more particularly, to heat-sealable paperboard structures having no to minimum tendency for blocking.
• Paperboard is used in various packaging applications. For example, coated unbleached paperboard is used to package beverage containers, frozen foods, cereals and a wide variety of other food and non-food consumer goods. Other forms of bleached and unbleached coated paperboard are used for a variety of packaging options in food service and consumer products.
• the aqueous heat-sealable barrier coatings cannot stand the temperature for calendering that is usually used to smoothen the coating surface. Blocking (the tendency of layers in a roll of paperboard to stick to one another) at elevated temperature and pressure is also a major technical challenge in production and converting processes for aqueous heat-sealable barrier coated paperboard. This blocking issue becomes even more critical for aqueous heat-sealable barrier coated paperboard that requires high barrier properties and also needs to be able to heat-seal in converting packages such as cups.
• the disclosed heat-sealable paperboard structure includes a paperboard substrate comprising a first major side and a second major side opposed from the first major side, a heat-sealable barrier coating on the first major side of the paperboard substrate, and a top coat positioned over the heat-sealable barrier coating, wherein the top coat forms a discontinuous layer over the heat-sealable barrier coating.
• the disclosed method for manufacturing a heat-sealable paperboard structure includes steps of (1) preparing a heat-sealable barrier coating formulation comprising a binder and a pigment, (2) applying the heat-sealable barrier coating formulation to a first major side of a paperboard substrate, (3) preparing a top coat formulation comprising a binder and a pigment, and (4) applying the top coat formulation over to the heat-sealable barrier coating to form a discontinuous layer of top coat over the heat-sealable barrier coating.
• FIG. 1 is an elevational view, in section, of one example of a container (e.g., a cup) that can be manufactured using the disclosed heat-sealable paperboard structures;
• a container e.g., a cup
• FIG. 2 is a top plan view of the container of Fig. 1;
• Fig. 3 is a plan view a die-cut blank that may be wrapped around a mandrel to form the side wall of the container of Fig. 1;
• Fig. 4 is a schematic cross-sectional view of one example of the disclosed heat- sealable paperboard structure
• FIG. 5 is a schematic cross-sectional view of another example of the disclosed heat- sealable paperboard structure
• FIG. 6 is a top view of an example heat-sealable paperboard structure taken using a scanning electron microscope at 200x magnification;
• Fig. 7 is a cross-sectional view of an example heat-sealable paperboard structure taken using a scanning electron microscope at lOOOx magnification
• FIG. 8 is an illustration of a device for testing blocking of coated paperboard samples. D ETAI L ED D E S C RIPTI ON
• a heat-sealable paperboard-based structure having a first major surface with high water barrier properties and minimal to no blocking tendencies can be achieved by positioning the heat-sealable barrier coating layer on the first major side of the underlying paperboard substrate, which has traditionally formed the first major surface of the structure, beneath a lower-binder, calenderable top coat applied as a discontinuous layer over (e.g., directly to) the barrier coating layer such that the heat- sealable barrier coating is positioned between the paperboard substrate and the top coat.
• Heat-sealability is provided by a heat-sealable barrier coating.
• Such a structure may be particularly well-suited for holding cold beverages (e.g., iced soft-drinks), cold foodstuffs (e.g., ice cream), hot beverages (e.g., coffee) and hot foodstuffs (e.g., soup).
• cold beverages e.g., iced soft-drinks
• cold foodstuffs e.g., ice cream
• hot beverages e.g., coffee
• hot foodstuffs e.g., soup
• a disclosed paperboard-based container may include a side wall 12 having an upper end portion 14 and a lower end portion 16, and a bottom wall 18 connected (e.g., heat-sealed) to the lower end portion 16 of the side wall 12, thereby defining an internal volume 20 within the container 10.
• the upper end portion 14 of the side wall 12 may define an opening 22 into the internal volume 20.
• the upper end portion 14 of the side wall 12 may additionally include a lip 24 (e.g., a rolled lip), such as for securing a lid (not shown) or the like to the container 10.
• a tall cup e.g., a 12-ounce, 16-ounce, 21 -ounce or 24-ounce disposable take-out cup
• a frustoconical side wall 12 e.g., a 12-ounce, 16-ounce, 21 -ounce or 24-ounce disposable take-out cup
• the disclosed container 10 may be formed in various shapes, sizes and configurations, and may be formed with fewer or more walls than the side and bottom walls 12, 18 discussed above, without departing from the scope of the present disclosure.
• the side wall 12 of the container 10 may be assembled from a blank 30 (Fig. 3) that has been cut to the desired silhouette and then wrapped around a mandrel (not shown). While the blank 30 is wrapped around the mandrel, the first end 32 of the blank 30 overlaps a second end 34 of the blank 30, and the overlapping ends 32, 34 may be connected (e.g., by heat-sealing), thereby defining a seam 36 that extends from the upper end portion 14 to the lower end portion 16 of the side wall 12.
• the bottom wall 18 may be connected (e.g., heat-sealed) to the lower end portion 16 of the side wall 12, thereby yielding the container 10.
• the side wall 12 of the container 10 may be formed from a paperboard structure 40 having a first major surface 42 and a second major surface 44.
• the first major surface 42 of the paperboard structure 40 may correspond to the interior surface 28 of the container 10.
• the second major surface 44 of the paperboard structure 40 may correspond to the exterior surface 26 of the container 10.
• the paperboard structure 40 may be a layered structure that includes a paperboard substrate 46 having a first major side 48 and a second major side 50.
• a heat-sealable barrier coating 52 and a top coat 54 may be applied to the first major side 48 of the paperboard substrate 46 such that the top coat 54 forms a discontinuous layer 56 over (e.g., directly adjacent) the heat-sealable barrier coating 52.
• the heat-sealable barrier coating 52 may be positioned between the top coat 54 and the paperboard substrate 46.
• the discontinuous layer 56 of top coat 54 may define, at least partially, the first major surface 42 of the paperboard structure 40 and, thus, the interior surface 28 of the container 10.
• the paperboard structure 40 may include a basecoat 45 between the paperboard substrate 46" and the heat-sealable barrier coating 52".
• the heat-sealable paperboard structure 40 may include a basecoat 47 on the second major side 50 of the paperboard substrate 46.
• the paperboard structure 40" may include a first basecoat 45 between the paperboard substrate 46' and the heat-sealable barrier coating 52' and a second basecoat 47 on the second major side 50 of the paperboard substrate 46".
• the paperboard substrate 46 of the paperboard structure 40 may be (or may include) any cellulosic material that is capable of being coated with the heat-sealable barrier coating 52 and the top coat 54.
• the paperboard substrate 46 may be bleached or unbleached. Examples of appropriate paperboard substrates include corrugating medium, linerboard, solid bleached sulfate (SBS) and unbleached kraft.
• the paperboard substrate 46 may have an uncoated basis weight of at least about 50 pounds per 3000 ft 2 . In one expression, the paperboard substrate 46 may have an uncoated basis weight ranging from about 60 pounds per 3000 ft 2 to about 400 pounds per 3000 ft 2 . In another expression, the paperboard substrate 46 may have an uncoated basis weight ranging from about 80 pounds per 3000 ft 2 to about 300 pounds per 3000 ft 2 . In another expression the paperboard substrate 46 may have an uncoated basis weight ranging from about 90 pounds per 3000 ft 2 to about 250 pounds per 3000 ft 2 . In yet another expression the paperboard substrate 46 may have an uncoated basis weight ranging from about 100 pounds per 3000 ft 2 to about 200 pounds per 3000 ft 2 .
• the paperboard substrate 46 may have a caliper (thickness) ranging, for example, from about 4 points to about 30 points (0.004 inch to 0.030 inch). In one expression, the caliper range is from about 8 points to about 24 points. In another expression, the caliper range is from about 12 points to about 20 points.
• a suitable paperboard substrate 46 is 13-point SBS cupstock manufactured by WestRock Company of Atlanta, Georgia. Another specific, nonlimiting example of a suitable paperboard substrate 46 is 16.5-point SBS cupstock manufactured by WestRock Company. Yet another specific, nonlimiting example of a suitable paperboard substrate 46 is 18-point SBS cupstock manufactured by WestRock Company.
• the heat-sealable barrier coating 52 may be applied to the first major side 48 of the paperboard substrate 46 using any suitable method, such as one or more coaters either on the paper machine or as off-machine coater(s). When heated, a heat-seal coating provides an adhesion to other regions of product with which it contacts.
• the heat-sealable barrier coating 52 may be applied to the paperboard substrate 46 at various coat weights. In one expression, the heat-sealable barrier coating 52 may be applied at a coat weight of about 4 to about 20 pounds per 3,000 ft 2 , as dried. In another expression, the heat-sealable barrier coating 52 may be applied at a coat weight of about 6 to about 16 pounds per 3,000 ft 2 , as dried. In yet another expression, the heat-sealable barrier coating 52 may be applied at a coat weight of about 8 to about 12 pounds per 3,000 ft 2 , as dried.
• the heat-sealable barrier coating 52 may include a binder and a pigment.
• the ratio of the pigment to the binder may be at most 1 part (by weight) pigment per 1 part (by weight) binder.
• the ratio of the pigment to the binder may be about 1:1 to about 1:9 by weight.
• the ratio of the pigment to the binder can be about 1:2 to about 1:6 by weight.
• the ratio of the pigment to the binder can be about 1:3 to about 1:4 by weight.
• the binder of the heat-sealable barrier coating 52 may be an aqueous binder.
• the binder may be a latex.
• the binder may be a water based acrylic emulsion polymer.
• a specific, non-limiting example of a suitable binder is presented in Table 2.
• Other aqueous binders are also contemplated, such as styrene-butadiene rubber (SBR), ethylene acrylic acid (EAA), polyvinyl acetate (PVAC), polyvinyl acrylic, polyester dispersion, and combinations thereof.
• the pigment component of the heat-sealable barrier coating 52 may be (or may include) various materials.
• suitable inorganic pigments are presented in Table 1.
• the pigment component of the heat-sealable barrier coating 52 may be a clay pigment.
• the clay pigment may be platy clay, such as a high aspect ratio platy clay (e.g., an average aspect ratio of at least 40:1, such as an average aspect ratio of at least 60:1).
• the pigment component of the heat-sealable barrier coating 52 may be a calcium carbonate (CaCCb) pigment.
• the CaCCb pigment may be a coarse ground CaCCb with a particle size distribution wherein about 60 percent of the particles are less than 2 microns.
• the CaCCb pigment may be a fine ground CaCCb with a particle size distribution wherein about 90 percent of the particles are less than 2 microns.
• the pigment component of the heat-sealable barrier coating 52 may be a pigment blend that includes both calcium carbonate pigment and clay pigment.
• the top coat 54 is applied to the heat-sealable barrier coating 52 to form a discontinuous layer 56 over (e.g., directly adjacent) the heat-sealable barrier coating 52.
• Various techniques may be used for forming the discontinuous layer 56 of top coat 54 over the heat-sealable barrier coating 52, such as one or more coaters either on the paper machine or as off-machine coater(s).
• the top coat 54 may be applied to the heat-sealable barrier coating 52 at various coat weights to achieve the discontinuous layer 56 of top coat 54.
• the top coat 54 may be applied at a coat weight of about 0.1 to 4.0 pounds per 3,000 ft 2 , as dried.
• the top coat 54 may be applied at a coat weight of about 0.5 to 3.0 pounds per 3,000 ft 2 , as dried.
• the top coat 54 may be applied at a coat weight of about 0.5 to 2.5 pounds per 3,000 ft 2 , as dried.
• the top coat 54 may be applied at a coat weight of about 0.5 to 2.0 pounds per 3,000 ft 2 , as dried.
• FIG. 6 an SEM was used to show a top view of the discontinuous layer 56 of top coat 54 deposited onto the heat-sealable barrier coating 52.
• the areas with the heat-sealable barrier coating 52 are darker, while the areas with both the heat-sealable barrier coating 52 and the top coat 54 are brighter.
• FIG. 7 an SEM was used to show a cross-section view of the discontinuous layer 56 of top coat 54 deposited onto the heat-sealable barrier coating 52.
• the top coat 54 may include a binder and a pigment.
• the pigments and binders useful for the heat-sealable barrier coating 52 may also be used in the top coat 54.
• the pigment-to-binder ratio of the top coat 54 may be significantly different from the pigment-to-binder ratio of the heat-sealable barrier coating 52.
• the ratio of the pigment to the binder in the top coat 54 can be at least about 1 part (by weight) pigment per 1 part (by weight) binder.
• the ratio of the pigment to the binder in the top coat 54 can be about 1:1 to about 10:1 by weight.
• the ratio of the pigment to the binder in the top coat 54 can be about 1:1 to about 5:1 by weight.
• the ratio of the pigment to the binder in the top coat 54 can be about 2:1 to about 4:1 by weight.
• the binder of the top coat 54 may be an aqueous binder.
• the binder may be a latex.
• the binder may be a water based acrylic emulsion polymer.
• aqueous binders are also contemplated, such as styrene-butadiene rubber (SBR), ethylene acrylic acid (EAA), polyvinyl acetate (PVAC), polyvinyl acrylic, polyester dispersion, and combinations thereof.
• the pigment component of the top coat 54 may be (or may include) various materials.
• suitable inorganic pigments are presented in Table 1.
• the pigment component of the top coat 54 may be a clay pigment.
• the clay pigment may be platy clay, such as a high aspect ratio platy clay (e.g., aspect ratio of at least 40:1).
• the pigment component of the top coat 54 may be a calcium carbonate (CaCCb) pigment.
• the CaCCb pigment can be a coarse ground CaCCb with a particle size distribution wherein about 60 percent of the particles are less than 2 microns.
• the CaCCb pigment can be a fine ground CaCCb with a particle size distribution wherein about 90 percent of the particles are less than 2 microns.
• the bottom wall 18 of the container 10 may be formed from a paperboard structure, such as the heat-sealable paperboard structure 40 shown in Fig. 4 or the heat-sealable paperboard structure 40" shown in Fig. 5.
• a paperboard structure such as the heat-sealable paperboard structure 40 shown in Fig. 4 or the heat-sealable paperboard structure 40" shown in Fig. 5.
• various other paperboard structures may be used to form the bottom wall 18, such as when printability of the bottom wall 18 is of little or no concern.
• the examples In addition to high smoothness, the examples also surprisingly exhibited excellent barrier properties, as evidenced by the 30-minute-water-Cobb results measured according to TAPPI Standard T441 om-04. For most cases, the additional discontinuous layer of the top coat improved or at least maintained the water barrier properties of the underneath heat-sealable barrier coating 52. All examples had 30-minute-water-Cobb ratings of less than 10 g/m 2 , with many below 4 g/m 2 .
• a hot coffee variant of the Cobb test was also utilized to evaluate the water barrier of the examples shown in Table 5. This test was performed by substituting 23 °C water with 90 °C coffee but otherwise complying TAPPI Standard T441 om-04. The coffee used was obtained by brewing 36 g of Starbucks medium house blend ground coffee with 1100 mL of distilled water in a 12 cup Mr. Coffee maker. All of the examples shown in Table 5 had a 90 °C coffee Cobb rating of less than 15 g/m 2 after 30 minutes, with most less than 10 g/m 2 after 30 minutes.
• the blocking rating (50 °C/60 psi/24 hrs), was less than 3.0 for all samples, indeed less than 2.1, and less than 1.0 for one sample.
• Table 6 defines the blocking test rating system.
• the blocking behavior of the samples was tested by evaluating the adhesion between the barrier coated side and the other uncoated side.
• a simplified illustration of the blocking test is shown in Fig. 8.
• the paperboard was cut into 2-inch by 2-inch square samples.
• Several duplicates were tested for each condition, with each duplicate evaluating the blocking between a pair of samples 252, 254. (For example, if four duplicates were test, four pairs - eight pieces - would be used.)
• Each pair was positioned with the ‘barrier- coated’ side of one piece 252 contacting the uncoated side of the other piece 254.
• the pairs were placed into a stack 250 with a spacer 256 between adjacent pairs, the spacer being foil, release paper, or even copy paper.
• the entire sample stack was placed into the test device 200 illustrated in Fig. 8.
• the test device 200 includes a frame 210.
• An adjustment knob 212 is attached to a screw 214 which is threaded through the frame top 216.
• the lower end of screw 214 is attached to a plate 218 which bears upon a heavy coil spring 220.
• the lower end of the spring 220 bears upon a plate 222 whose lower surface 224 has an area of one square inch.
• a scale 226 enables the user to read the applied force (which is equal to the pressure applied to the stack of samples through the one-square-inch lower surface 224).
• the stack 250 of samples is placed between lower surface 224 and the frame bottom 228.
• the knob 212 is tightened until the scale 226 reads the desired force of 100 lbf (100 psi applied to the samples) or 60 lbf (60 psi applied to the samples).
• High pressure such as lOOOpsi is achieved by reducing the lower surface area of 224 contacting the stack 250 of samples to 0.11 square inch, with an applied force of 110 lb.
• the entire device 200 including samples is then placed in an oven at 50 °C for 24 hours or 2 hours.
• the device 200 is then removed from the test environment and cooled to room temperature. The pressure is then released, and the samples removed from the device.
• samples 252(0)/254(0) might be representative of a “0” rating (no blocking).
• the circular shape in the samples indicates an approximate area that was under pressure, for instance about one square inch of the overall sample.
• Samples 252(3)/254(3) might be representative of a “3” blocking rating, with up to 25% fiber tear in the area that was under pressure, particularly in the uncoated surface of sample 254(3).
• Samples 252(4)/254(4) might be representative of a 4 blocking rating with more than 25% fiber tear, particularly in the uncoated surface of sample 254(4).
• the depictions in Fig. 8 are only meant to approximately suggest the percent damage to such test samples, rather than showing a realistic appearance of the samples.

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• Engineering & Computer Science (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
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• Wrappers (AREA)

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• 2021
  • 2021-01-13 CN CN202180023385.1A patent/CN115279970A/zh active Pending
  • 2021-01-13 WO PCT/US2021/013165 patent/WO2021150404A1/en unknown
  • 2021-01-13 JP JP2022544377A patent/JP2023511176A/ja active Pending
  • 2021-01-13 EP EP21706412.0A patent/EP4093913A1/de active Pending
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  • 2021-01-13 CA CA3165612A patent/CA3165612A1/en active Pending
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