CN115279970B

CN115279970B - Heat sealable paperboard structure and method

Info

Publication number: CN115279970B
Application number: CN202180023385.1A
Authority: CN
Inventors: 逄杰斌
Original assignee: WestRock MWV LLC
Current assignee: WestRock MWV LLC
Priority date: 2020-01-22
Filing date: 2021-01-13
Publication date: 2024-06-04
Anticipated expiration: 2041-01-13
Also published as: JP2023511176A; EP4093913A1; US20210222370A1; BR112022014447A2; CN115279970A; WO2021150404A1; CA3165612A1

Abstract

A heat sealable paperboard structure comprising: a paperboard substrate having a first major face and a second major face opposite the first major face; a heat sealable barrier coating on the first major face of the paperboard substrate; and a topcoat layer positioned over the heat-sealable barrier coating layer, wherein the topcoat layer forms a discontinuous layer over the heat-sealable barrier coating layer.

Description

Heat sealable paperboard structure and method

Priority

The present application claims priority from U.S. Ser. No. 62/964,198 submitted at 22/1/2020.

Technical Field

The present application relates to paperboard structures, and more particularly, to heat sealable paperboard structures that have no or minimal tendency to block.

Background

Paperboard is used in a variety of packaging applications. For example, coated unbleached paperboard is used in packaging beverage containers, frozen foods, cereals and a wide variety of other food and non-food consumer products. Other forms of bleached and unbleached coated paperboard are used in various packaging options for food service and consumer goods.

Sustainability is one of the key driving forces in developing new packages for food and non-food consumer products. Paperboard structures coated with aqueous coatings are generally considered repulpable and recyclable and are therefore more sustainable than paperboard coated with extruded Low Density Polyethylene Extrudates (LDPE). However, most polymers in aqueous coatings are amorphous and do not have a melting point like LDPE. Thus, during the production, storage, transportation or processing of aqueous coated paperboard, the binder or polymer in the aqueous coating often softens or becomes tacky at high temperatures (even at, for example, 120-130°f) and/or pressures, thereby causing blocking problems in the coated paperboard, which typically does not occur in practical applications for polyethylene coated paperboard.

Furthermore, due to the high adhesive level and thus the hot tack, the aqueous heat sealable barrier coating cannot withstand the calendering temperatures typically used to smooth the coating surface. Blocking (the tendency of layers in a paperboard roll to block each other) at elevated temperatures and pressures is also a major technical challenge in the production and processing of waterborne heat sealable barrier coated paperboard. This blocking problem becomes more critical for waterborne heat-sealable barrier coated paperboard, which requires high barrier properties and which also needs to be able to be heat sealed in process packages such as cups.

Accordingly, those skilled in the art continue to research and develop in the field of heat sealable barrier paperboard structures using aqueous coatings.

Disclosure of Invention

Heat sealable paperboard structures are disclosed that have no or minimal blocking tendency.

In one example, the disclosed heat-sealable paperboard structure includes a paperboard substrate including a first major face and a second major face opposite the first major face, a heat-sealable barrier coating on the first major face of the paperboard substrate, and a top coating positioned on the heat-sealable barrier coating, wherein the top coating forms a discontinuous layer on the heat-sealable barrier coating.

Also disclosed are methods for making heat sealable paperboard structures having no or minimal tendency to blocking.

In one example, the disclosed method for manufacturing a heat sealable paperboard structure includes the steps of: (1) preparing a heat-sealable barrier coating formulation comprising an adhesive and a pigment, (2) applying the heat-sealable barrier coating formulation to the first major face of the paperboard substrate, (3) preparing a top coating formulation comprising an adhesive and a pigment, and (4) applying the top coating formulation to the heat-sealable barrier coating to form a discontinuous layer of the top coating on the heat-sealable barrier coating.

Other examples of the disclosed heat sealable paperboard structures and methods will become apparent from the following detailed description, drawings, and appended claims.

Drawings

FIG. 1 is a cross-sectional elevation view of one example of a container (e.g., cup) that can be made using the disclosed heat-sealable paperboard structures;

FIG. 2 is a top plan view of the container of FIG. 1;

FIG. 3 is a plan view of 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 cardboard structure taken at 200x magnification using a scanning electron microscope;

FIG. 7 is a cross-sectional view of an example heat sealable cardboard structure taken at 1000x magnification using a scanning electron microscope; and

Fig. 8 is a schematic view of an apparatus for testing the blocking of coated paperboard samples.

Detailed Description

It has now been found that a heat sealable paperboard-based structure having a first major surface with high water blocking properties and minimal non-blocking tendency can be achieved by positioning a heat sealable barrier coating on the first major surface of a base paperboard substrate that conventionally forms the first major surface of the structure, under a low adhesive, calenderable top coat applied as a discontinuous layer on (e.g., directly applied to) the barrier coating such that the heat sealable barrier coating is positioned between the paperboard substrate and the top coat. The heat sealability is provided by the heat sealable barrier coating. Such a structure may be particularly suitable for preserving cold beverages (e.g., ice soft drinks), cold foods (e.g., ice cream), hot beverages (e.g., coffee), and hot foods (e.g., soups).

Referring to fig. 1 and 2, one example of a disclosed paperboard-based container, generally designated 10, may include a side wall 12 having an upper end 14 and a lower end 16, and a bottom wall 18 connected (e.g., heat sealed) to the lower end 16 of the side wall 12, thereby defining an interior volume 20 within the container 10. The upper end 14 of the sidewall 12 may define an opening 22 to the interior volume 20. Optionally, the upper end 14 of the sidewall 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.

Although the container 10 is illustrated in fig. 1 as a tall cup (e.g., a 12 ounce, 16 ounce, 21 ounce, or 24 ounce disposable take-away cup) having a frustoconical sidewall 12, those skilled in the art will appreciate that the disclosed container 10 may be formed in a variety of shapes, sizes, and configurations and may be formed with fewer or more walls than the above-described sidewalls and bottom walls 12, 18 without departing from the scope of the present disclosure.

As shown in fig. 2, the side walls 12 of the container 10 may be assembled from a blank 30 (fig. 3), which blank 30 has been cut to a desired profile and then wrapped around a mandrel (not shown). When the blank 30 is wrapped around the mandrel, the first end 32 of the blank 30 overlaps the second end 34 of the blank 30, and the overlapping ends 32, 34 may be joined (e.g., by heat sealing) to define a seam 36 extending from the upper end 14 to the lower end 16 of the side wall 12. Once the side wall 12 has been assembled, the bottom wall 18 may be attached (e.g., heat sealed) to the lower end 16 of the side wall 12, thereby creating the container 10.

Referring to fig. 4, 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 outer 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 face 48 and a second major face 50. The heat-sealable barrier coating 52 and the top coating 54 may be applied to the first major face 48 of the paperboard substrate 46 such that the top coating 54 forms a discontinuous layer 56 on (e.g., immediately adjacent to) the heat-sealable barrier coating 52. The heat sealable barrier coating 52 may be positioned between the top coating 54 and the paperboard substrate 46. The discontinuous layer 56 of the top coat 54 may at least partially define the first major surface 42 of the paperboard structure 40, and thus the inner surface 28 of the container 10.

In this regard, those skilled in the art will appreciate that various additional layers, barrier layers, or non-barrier layers may be incorporated into the paperboard structure 40 between the paperboard substrate 46 and the discontinuous layer 56, or on top of the second major face 50, without departing from the scope of this disclosure. In one variation, as shown in fig. 5, the paperboard structure 40 ' may include a primer layer 45 between the paperboard substrate 46 ' and the heat sealable barrier coating 52 '. In another variation, as shown in fig. 5, the heat sealable paperboard structure 40 may include a primer layer 47 on the second major face 50 of the paperboard substrate 46'. In yet another variation, as shown in fig. 5, the paperboard structure 40 may include a first primer layer 45 between the paperboard substrate 46 'and the heat sealable barrier coating 52' and a second primer layer 47 on the second major face 50 of the paperboard substrate 46.

Referring back to fig. 4, the paperboard substrate 46 of the paperboard structure 40 may be (or may include) any cellulosic material capable of being coated with a heat sealable barrier coating 52 and a top coating 54. Those skilled in the art will appreciate that the paperboard substrate 46 may be bleached or unbleached. Examples of suitable paperboard substrates include corrugated medium, linerboard, solid Bleached Sulfate (SBS), and unbleached kraft paper.

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 lbs/3000 ft ² to about 250 lbs/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.

Further, 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 ranges from about 8 points to about 24 points. In another expression, the caliper ranges from about 12 points to about 20 points.

One specific non-limiting example of a suitable paperboard substrate 46 is 13-point SBS cup blank (SBS cupstock) manufactured by WestRock company, atlanta, georgia. Another specific non-limiting example of a suitable paperboard substrate 46 is a 16.5 point SBS cup blank manufactured by WestRock company. Another specific non-limiting example of a suitable paperboard substrate 46 is an 18-point SBS cup blank manufactured by WestRock company.

The heat sealable barrier coating 52 may be applied to the first major face 48 of the paperboard substrate 46 using any suitable method, such as one or more coaters, either on a paper machine or as an off-machine coater. When heated, the heat seal coating provides adhesion to other areas of the product that are in contact therewith.

The heat sealable barrier coating 52 may be applied to the paperboard substrate 46 at various coating weights. In one expression, the heat-sealable barrier coating 52 may be applied at a coating weight of from about 4 to about 20 pounds per 3000 ft ² (dry weight). In another expression, the heat-sealable barrier coating 52 may be applied at a coating weight of from about 6 to about 16 pounds per 3000 ft ² (dry weight). In another expression, the heat-sealable barrier coating 52 may be applied at a coating weight of about 8 to about 12 pounds per 3000 ft ² (dry weight).

The heat sealable barrier coating 52 may include an adhesive and a pigment. In one expression, the ratio of pigment to binder may be up to 1 part (by weight) of pigment per 1 part (by weight) of binder. In another expression, the weight ratio of pigment to binder may be about 1:1 to about 1:9. In yet another expression, the weight ratio of pigment to binder may be from about 1:2 to about 1:6. In yet another expression, the weight ratio of pigment to binder may be from about 1:3 to about 1:4.

In a particular embodiment, the adhesive of the heat sealable barrier coating 52 may be an aqueous adhesive. As a general non-limiting example, the binder may be latex. As another general non-limiting example, the binder may be a water-based acrylic emulsion polymer. Specific non-limiting examples of suitable binders are given in table 2. Other aqueous binders are also contemplated, such as styrene-butadiene rubber (SBR), ethylene Acrylic Acid (EAA), polyvinyl acetate (PVAC), polyethylene acrylic acid, polyester dispersions, and combinations thereof.

The pigment component of the heat sealable barrier coating 52 may be (or may include) a variety of materials. Several non-limiting examples of suitable inorganic pigments are given in table 1. Other pigments, such as plastic pigments, titanium dioxide pigments, talc pigments, etc., may be used without departing from the scope of the invention.

In one variation, the pigment component of the heat sealable barrier coating 52 may be a clay pigment. As one example, the clay pigment may be a 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).

In another variation, the pigment component of the heat sealable barrier coating 52 may be a calcium carbonate (CaCO ₃) pigment. As one example, the CaCO ₃ pigment may be coarse ground CaCO ₃ having a particle size distribution in which about 60% of the particles are less than 2 microns. As another example, the CaCO ₃ pigment may be finely ground CaCO ₃ having a particle size distribution in which about 90% of the particles are less than 2 microns.

In yet another variation, the pigment component of the heat sealable barrier coating 52 may be a pigment mixture comprising both a calcium carbonate pigment and a clay pigment.

A top coat 54 is applied to the heat-sealable barrier coating 52 to form a discontinuous layer 56 on (e.g., immediately adjacent to) the heat-sealable barrier coating 52. Various techniques may be used to form the discontinuous layer 56 of the topcoat 54 over the heat-sealable barrier coating 52, such as one or more coaters on a paper machine or as an off-machine coater.

The top coat 54 may be applied to the heat sealable barrier coating 52 at various coat weights to achieve a discontinuous layer 56 of the top coat 54. In one expression, the top coat 54 may be applied at a coat weight of about 0.1 to 4.0 pounds per 3000 ft ² (dry weight). In another expression, the topcoat 54 may be applied at a coat weight of about 0.5 to 3.0 pounds per 3000 ft ² (dry weight). In another expression, the topcoat 54 may be applied at a coat weight of about 0.5 to 2.5 pounds per 3000 ft ² (dry weight). In yet another expression, the topcoat 54 may be applied at a coat weight (dry weight) of about 0.5 to 2.0 lbs/3000 ft ².

Referring to fig. 6, an sem is used to show a top view of the discontinuous layer 56 of the top coat 54 deposited onto the heat sealable barrier coating 52. The area with the heat sealable barrier coating 52 is darker, while the area with both the heat sealable barrier coating 52 and the top coating 54 is lighter.

Referring to fig. 7, sem is used to show a cross-sectional view of a discontinuous layer 56 of a top coat 54 deposited onto a heat sealable barrier coating 52.

The top coat 54 may include a binder and a pigment. Pigments and binders useful in the heat seal barrier coating 52 may also be used in the topcoat 54. However, the pigment to binder ratio of the top coat 54 may be significantly different than the pigment to binder ratio of the heat sealable barrier coating 52. In one expression, the pigment to binder ratio in the topcoat 54 may be at least about 1 part (by weight) pigment per 1 part (by weight) binder. In another expression, the weight ratio of pigment to binder in the topcoat 54 may be about 1:1 to about 10:1. In another expression, the weight ratio of pigment to binder in the topcoat 54 may be about 1:1 to about 5:1. In yet another expression, the weight ratio of pigment to binder in the topcoat 54 may be about 2:1 to about 4:1.

In a particular embodiment, the adhesive of the top coat 54 may be an aqueous adhesive. As a general non-limiting example, the binder may be latex. As another general non-limiting example, the binder may be a water-based acrylic emulsion polymer. One specific non-limiting example of a suitable adhesive is given in table 2. Other aqueous binders are also contemplated, such as styrene-butadiene rubber (SBR), ethylene Acrylic Acid (EAA), polyvinyl acetate (PVAC), polyethylene acrylic acid, polyester dispersions, and combinations thereof.

The pigment component of the topcoat 54 may be (or may include) a variety of materials. Several non-limiting examples of suitable inorganic pigments are given in table 1. Other pigments, such as plastic pigments, titanium dioxide pigments, talc pigments, etc., may be used without departing from the scope of the invention.

In one variation, the pigment component of the topcoat 54 may be a clay pigment. As one example, the clay pigment may be a platy clay, such as a high aspect ratio platy clay (e.g., an aspect ratio of at least 40:1).

In another variation, the pigment component of the top coat 54 may be a calcium carbonate (CaCO ₃) pigment. As one example, the CaCO ₃ pigment may be coarse ground CaCO ₃ having a particle size distribution in which about 60% of the particles are less than 2 microns. As another example, the CaCO ₃ pigment may be finely ground CaCO ₃ having a particle size distribution in which about 90% of the particles are less than 2 microns.

Referring back to fig. 1, 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. 4or the heat-sealable paperboard structure 40 shown in fig. 5. However, various other paperboard structures may be used to form the bottom wall 18, such as when printability of the bottom wall 18 is less important or unimportant.

Example

Experiments were conducted to evaluate the use of discontinuous layers of a top coat on a heat sealable barrier coating in relation to paperboard structures. A heat sealable barrier coating formulation (BC 1) and a top coat formulation (TC 1) were prepared and used in the experiments. The pigments used in the formulation are given in table 1. The binders used in the formulation are given in table 2. The heat sealable barrier coating formulation (BC 1) is given in table 3. The topcoat formulation (TC 1) is given in Table 4.

TABLE 1

Name of the name	Pigment	Description of the invention
			CL-1	BARRISURF ™ XP (Georgia IMERYS kaolin)	Platy clays with high aspect ratios
CC-1	Hydrocararb ^® 60 (Omya AG of the Olympic root of Switzerland)	Coarse grinding CaCO ₃ (particle size 60% <2 microns)
			CC-2	HYDROCARB^® 90 （Omya AG）	Finely ground CaCO ₃ (particle size 90% < 2 microns)

TABLE 2

Name of the name	Adhesive agent	Description of the invention
			SA-1	CARTASEAL ^® SCR (Archroma, reinach, switzerland)	Water-based acrylic emulsion polymer with Tg of 30deg.C

TABLE 3 Table 3

	Barrier coating formula (parts)
			BC-1
CaCO₃（CC-1）	65
		CaCO₃（CC-2）
Clay (CL-1)	35
		Adhesive (SA-1)	400

TABLE 4 Table 4

	Top coat formula (parts)
			TC-1
CaCO₃（CC-1）
		CaCO₃（CC-2）	100
Clay (CL-1)
		Adhesive (SA-1)	50

The formulation was applied at different coat weights to 16.5 point solid bleached sulfate cup blanks having basis weights of 175 pounds per 3000 square feet. The heat sealable barrier coating formulation was applied to the felt side of the paperboard substrate using a knife coater. The top coat formulation was again applied to the heat sealable barrier coating using a knife coater to produce a two-layer coating on the felt side of the paperboard substrate. Examples and experimental results (Parker print surface smoothness; water puffer; coffee puffer; blocking grade; and heat sealability) are shown in Table 5.

TABLE 5

。

Thus, the use of a discontinuous layer of top coat on the heat sealable barrier coating of the paperboard structure provides a smooth surface as shown by Parker print surface (PPS-10S) smoothness results measured according to TAPPI Standard T555. All examples of the disclosed heat sealable paperboard structures exhibit PPS smoothness of 3 microns or less.

In addition to high smoothness, these examples also surprisingly demonstrate excellent barrier properties as demonstrated by the 30 minute water-puffer result measured according to TAPPI standard T441 om-04. For most cases, the additional discontinuous layer of the top coat improves or at least maintains the water blocking properties of the underlying heat sealable barrier coating 52. All examples had a 30 minute water-bob rating of less than 10 g/m ², many below 4 g/m ².

The hot coffee variant of the puffer test was also used to evaluate the water resistance of the examples shown in table 5. The test was performed by replacing 23 ℃ water with 90 ℃ coffee, but otherwise conforming to TAPPI standard T441 om-04. The coffee used was obtained by moderately preparing a mixed ground coffee by brewing 36g of starbucks with 1100 mL distilled water in a 12 cup mr. Coffee machine. All examples shown in table 5 have a 90 ℃ coffee puffer rating of less than 15 g/m ² after 30 minutes, most less than 10 g/m ² after 30 minutes.

The heat sealability of the coated samples of table 5 was evaluated on a PMC (paper machine company) cup machine, PMC-1250 model, by using each of these samples as the sidewall of the cup and a control bottom blank for all cups. All cups were successfully formed and the percentage of fiber tear over the seam area upon tearing the heat sealed sidewall seam was estimated. A high fiber tear percentage means better heat sealability. Samples 1 and 2 both exhibited 100% fiber tear, similar to the control sample without the discontinuous layer of the top coat, and samples 3 and 4 also exhibited 95% excellent fiber tear.

Finally, the blocking rating (50 ℃ C./60 psi/24 hours) was less than 3.0 for all samples, actually less than 2.1, and less than 1.0 for one sample. Table 6 defines the adhesion test rating system.

TABLE 6

Grade	Description of the invention
		0	Sample breaks without any applied force
1	The sample had slight tackiness, but separated without fiber tearing
		2	The samples were highly viscous but separated without fiber tearing
3	The sample was tacky and up to 25% of the fiber torn or coating damaged (based on area)
		4	Samples have more than 25% fiber tear or coating failure (based on area)

The blocking behavior of the samples was tested by evaluating the adhesion between the barrier coated side and the other uncoated side. Fig. 8 shows a simplified illustration of a blocking test. The cardboard was cut into square samples of 2 inches by 2 inches. Several replicates were tested for each condition, with each replicate evaluating adhesion between a pair of samples 252, 254. (e.g., if four copies were tested, four pairs (eight pieces) would be used). Each pair is positioned such that the "barrier coated" face of one piece 252 contacts the uncoated face of the other piece 254. These pairs are placed in stack 250 with a spacer 256 between adjacent pairs, which is foil, release paper or even copy paper. The entire sample stack is placed into the test device 200 shown in fig. 8.

The test apparatus 200 includes a frame 210. The adjustment knob 212 is attached to a screw 214 threaded through a frame top 216. The lower end of the screw 214 is attached to a plate 218, the plate 218 being carried on a heavy coil spring 220. The lower end of the spring 220 is carried on a plate 222, the area of the lower surface 224 of the plate 222 being 1 square inch. The scale 226 enables a user to read the applied force (which is equal to the pressure applied to the sample stack through the one square inch lower surface 224).

Sample stack 250 is placed between lower surface 224 and frame bottom 228. Knob 212 is tightened until scale 226 reads the force required of 100 pounds force (100 psi applied to the sample) or 60 pounds force (60 psi applied to the sample). High pressures, such as 1000 psi, are achieved by reducing the lower surface area 224 of the contact sample stack 250 to 0.11 square inches with a 110 pound applied force. The entire device 200 including the sample was then placed in an oven at 50 ℃ for 24 hours or 2 hours. The device 200 is then removed from the test environment and cooled to room temperature. The pressure was then released and the sample was removed from the device.

The tackiness and blocking of the samples were evaluated by separating each pair of cardboard sheets. Blocking damage is visible as fiber tearing, which typically occurs when the fibers are pulled from the non-blocking surface of sample 254, if present. Damage to the printed coating may also exhibit blocking if the non-blocking surface is coated with the printed coating.

For example, as symbolically depicted in fig. 8, samples 252 (0)/254 (0) may represent a "0" scale (no blocking). The circular shape in the sample indicates an approximate area under pressure, for example, about one square inch of the entire sample. Samples 252 (3)/254 (3) may represent a "3" blocking rating with fiber tear of up to 25% in the pressed area, particularly on the uncoated surface of sample 254 (3). Samples 252 (4)/254 (4) may represent a "4" blocking rating with fiber tear exceeding 25%, particularly in the uncoated surface of sample 254 (4). The depiction in fig. 8 is meant only to approximately suggest the percent damage to such test samples, rather than to show the actual appearance of the sample.

While various examples of the disclosed heat sealable paperboard structure and method have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The application includes such modifications and is limited only by the scope of the claims.

Claims

1. A heat sealable paperboard container structure comprising:

a paperboard substrate comprising a first major face and a second major face opposite the first major face, the first major face corresponding to an interior of the container structure;

a heat sealable barrier coating on a first major face of the paperboard substrate; and

A top coat positioned over the heat sealable barrier coating, wherein the top coat comprises a binder and a pigment, wherein a weight ratio of the pigment to the binder in the top coat is at least 1:1, wherein the top coat forms a discontinuous layer over the heat sealable barrier coating, wherein the discontinuous layer has a coating weight ranging from 0.1lb/3000ft ² to 4.0lb/3000ft ².

2. The heat sealable paperboard container structure of claim 1, wherein the weight ratio of pigment to binder in the top coat is from 1:1 to 10:1.

3. The heat sealable paperboard container structure of claim 1, wherein the weight ratio of pigment to binder in the top coat is from 1:1 to 5:1.

4. The heat sealable paperboard container structure of claim 1, wherein the weight ratio of pigment to binder in the top coat is from 2:1 to 4:1.

5. The heat sealable paperboard container structure of any of claims 1-4, wherein the adhesive comprises an aqueous adhesive.

6. The heat sealable paperboard container structure of any of claims 1-4, wherein the adhesive comprises latex.

7. The heat sealable paperboard container structure of any of claims 1-4, wherein the adhesive comprises a water-based acrylic emulsion polymer.

8. The heat sealable paperboard container structure of any of claims 1-4, wherein the adhesive comprises a water-based acrylic emulsion polymer having a glass transition temperature of 30 ℃.

9. The heat sealable paperboard container structure of any of claims 1 to 4, wherein the pigment comprises calcium carbonate.

10. The heat sealable paperboard container structure of any of claims 1-4, wherein the pigment comprises ground calcium carbonate, and wherein up to 90% of the ground calcium carbonate has a particle size of less than 2 microns.

11. The heat sealable paperboard container structure of any of claims 1-4, wherein the discontinuous layer has a coating weight of from 0.5lb/3000ft ² to 3.0lb/3000ft ².

12. The heat sealable paperboard container structure of any of claims 1-4, wherein the discontinuous layer has a coating weight of from 0.5lb/3000ft ² to 2.5lb/3000ft ².

13. The heat sealable paperboard container structure of any of claims 1-4, wherein the discontinuous layer has a coating weight of from 0.5lb/3000ft ² to 2.0lb/3000ft ².

14. The heat sealable paperboard container structure of any of claims 1-4, wherein the heat sealable barrier coating comprises an adhesive and a pigment.

15. A heat sealable paperboard container structure as in claim 14, wherein the pigment to binder weight ratio in the heat sealable barrier coating is at most 1:1.

16. A heat sealable paperboard container structure as in claim 14, wherein the pigment to binder weight ratio in the heat sealable barrier coating is from 1:1 to 1:9.

17. The heat sealable paperboard container structure of claim 14, wherein the weight ratio of pigment to binder in the heat sealable barrier coating is from 1:2 to 1:6.

18. The heat sealable paperboard container structure of claim 14, wherein the weight ratio of pigment to binder in the heat sealable barrier coating is from 1:3 to 1:4.

19. The heat sealable paperboard container structure of claim 14, wherein the adhesive comprises latex.

20. The heat sealable paperboard container structure of claim 14, wherein the adhesive comprises a water-based acrylic emulsion polymer having a glass transition temperature of 30 ℃.

21. The heat sealable cardboard container structure of claim 14 wherein the pigment comprises a first pigment and a second pigment.

22. The heat sealable cardboard container structure of claim 14, wherein the pigment comprises at least one of clay and calcium carbonate.

23. The heat sealable paperboard container structure of claim 14, wherein the pigment comprises ground calcium carbonate, and wherein up to 60% of the ground calcium carbonate has a particle size of less than 2 microns.

24. The heat sealable cardboard container structure of claim 14 wherein the pigment comprises a platy clay.

25. The heat sealable paperboard container structure of claim 24, wherein the platy clay has an average aspect ratio of at least 40:1.

26. The heat sealable paperboard container structure of any of claims 1-4, wherein the heat sealable barrier coating has a coating weight ranging from 4lb/3000ft ² to 20lb/3000ft ².

27. The heat sealable paperboard container structure of any of claims 1-4, wherein the heat sealable barrier coating has a coating weight ranging from 6lb/3000ft ² to 16lb/3000ft ².

28. The heat sealable paperboard container structure of any of claims 1-4, wherein the heat sealable barrier coating has a coating weight ranging from 8lb/3000ft ² to 12lb/3000ft ².

29. The heat sealable paperboard container structure of any of claims 1-4, wherein the paperboard substrate comprises solid bleached sulfate.

30. The heat sealable paperboard container structure of any of claims 1-4, wherein the paperboard substrate has a basis weight ranging from 80lb/3000ft ² to 300lb/3000ft ².

31. The heat sealable paperboard container structure of any of claims 1-4, wherein the caliper of the paperboard substrate ranges from 4 to 30 points.

32. The heat sealable paperboard container structure of any of claims 1-4, wherein the paperboard substrate has a thickness ranging from 8 to 24 points.

33. The heat sealable paperboard container structure of any of claims 1-4, wherein the paperboard substrate has a thickness ranging from 12 to 20 points.

34. The heat sealable paperboard container structure of any of claims 1-4, further comprising one or more coatings positioned between the paperboard substrate and the heat sealable barrier coating.

35. The heat sealable paperboard container structure of any of claims 1-4, further comprising one or more coatings on the second major face.

36. The heat sealable paperboard container structure of any of claims 1-4, having a parker print surface smoothness of at most 3.1 μιη.

37. The heat sealable paperboard container structure of any of claims 1-4, having a parker print surface smoothness of at most 2.5 μιη.

38. The heat sealable paperboard container structure of any of claims 1-4, having a parker print surface smoothness of at most 2 μιη.

39. The heat sealable paperboard container structure of any of claims 1-4, having a 30 minute water-bob rating of at most 10g/m ².

40. The heat sealable paperboard container structure of any of claims 1-4, having a 30 minute water-bob rating of at most 5g/m ².

41. The heat sealable paperboard container structure of any of claims 1-4, having a 30 minute water-bob rating of at most 3g/m ².

42. The heat sealable paperboard container structure of any of claims 1-4, having a 30 minute coffee erection rating of at most 15g/m ² at 90 ℃.

43. The heat sealable paperboard container structure of any of claims 1-4, having a 30 minute coffee erection rating of at most 12g/m ² at 90 ℃.

44. The heat sealable paperboard container structure of any of claims 1-4, having a 30 minute coffee erection rating of at most 9g/m ² at 90 ℃.

45. The heat sealable paperboard container structure of any of claims 1-4 having a blocking rating of less than 2 at 50 ℃ and 60psi over a 24 hour period.

46. The heat sealable paperboard container structure of any of claims 1-4 having a blocking rating of less than 1.7 at 50 ℃ and 60psi over a 24 hour period.

47. The heat sealable paperboard container structure of any of claims 1-4 having a blocking rating of less than 1.4 at 50 ℃ and 60psi over a 24 hour period.

48. The heat sealable paperboard container structure of any of claims 1-4, having a heat sealability of at least 95% fiber tear.

49. The heat sealable paperboard container structure of any of claims 1-4, wherein the heat sealable paperboard container structure is a cup.

50. A method for manufacturing a container, comprising:

preparing a heat sealable barrier coating formulation comprising a binder and a pigment;

applying the heat-sealable barrier coating formulation to the first major face of the paperboard substrate to form a heat-sealable barrier coating;

Preparing a top coat formulation comprising a binder and a pigment, wherein the weight ratio of the pigment to the binder in the top coat is at least 1:1;

Applying the topcoat formulation over the heat-sealable barrier coating layer to form a discontinuous layer of topcoat over the heat-sealable barrier coating layer, wherein the discontinuous layer has a coating weight ranging from 0.1lb/3000ft ² to 4.0lb/3000ft ²; and

A container is formed comprising a coated paperboard substrate, the first major face corresponding to an interior of the container.

51. The method of claim 50, wherein the heat sealable barrier coating formulation is applied to the first major face of the paperboard substrate using a knife coater.

52. The method of claim 50 or 51, wherein the topcoat formulation is applied directly to the heat sealable barrier coating formulation using a doctor blade coater.

53. The method of claim 50 or 51, further comprising drying the heat sealable barrier coating formulation.

54. The method of claim 50 or 51, further comprising drying the topcoat formulation.