Repulpable, paper-based backing layer

Abstract

The present invention relates to a backing layer comprising an inorganic filler and a barrier coating layer comprising a polymer having a glass transition temperature of -35°C to +15°C.

Description

[Technical Field]

[0001] The present disclosure relates to a paper-based backing layer. The backing layer includes several layers, particularly a paper layer, and a barrier coating layer that may include a polymer and an inorganic filler. The backing layer can be used in tapes, labels, and related products. [Background technology]

[0002] The paper-based backing layer forms the framework for various tapes (closure tapes, tear tapes (e.g., tear tapes), and reinforcing tapes), labels, and related products, onto which printing can be applied. The paper-based backing layer often includes several coatings applied in layers onto a paper support.

[0003] Because tapes, labels, and related products are affixed to cardboard boxes, letters, envelopes, etc., the entire material undergoes a recycling process. In the recycling process, the material is fed into a pulper, where it is mechanically treated in water with a neutral to alkaline pH to break down the paper into cellulose fibers. This is followed by several purification steps, such as screening and flotation, ultimately resulting in a slurry containing cellulose fibers. The slurry is expected to meet the requirements for feeding papermaking machines.

[0004] During the processing of recycled paper-derived cellulose slurries through papermaking machines, machine interruptions and downtimes occur frequently, reducing the efficiency of the recycling process.

[0005] The interruptions are caused by so-called "stickies", which are agglomerates or even clumps of sticky polymers that originate from coatings applied to the paper support and that could not be removed from the cellulose fibers during the refining of the cellulose slurry. Stickies are visible as fatty spots on recycled paper sheets. They are responsible for the recycled paper sheets sticking to each other. Stickies adhere to the rollers, thereby affecting the quality of the paper web during production, thereby reducing production efficiency and increasing production costs.

[0006] A certain percentage of sticky polymer agglomerates and clumps are separated from the slurry during refining by sieves, screens, and filters. However, the refining is incomplete. In addition, the removed sticky polymer agglomerates and clumps are not recyclable. They end up in the waste stream and are landfilled or incinerated. This should be avoided from an environmental perspective.

[0007] Thus, even though they include a paper-based backing layer, conventional tapes, labels and related products can only be recycled to an insufficient extent.

[0008] Recyclability can be measured according to the "Voluntary Standard For Repulping and Recycling Corrugated Fiberboard Treated to Improve Its Performance in the Presence of Water and Water Vapor" (revised August 16, 2013) published by the Fibre Box Association (FBA), USA, which includes guidelines for measuring the recyclability of the fibre and the percentage of sticky content in recycled products. The standard sets requirements for a fibre recyclability of at least 85% based on the oven-dry fibre input to the pulper; and a sticky content of 15 or less.

[0009] Conventional paper-based backing layers exhibit fiber recyclability values ​​of approximately % and sticky matter percentages of about 100 or more. From the standpoint of manufacturing efficiency and environmental pollution, these values ​​are disadvantageous. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] "Voluntary Standard For Repulping and Recycling Corrugated Fiberboard Treated to Improve Its Performance in the Presence of Water and Water Vapor" (revised August 16, 2013) issued by the Corrugated Board Association (FBA) Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, there is a need in the art to provide a paper-based backing layer that exhibits improved recyclability and improved manufacturing efficiency. Such a paper-based backing layer is expected to exhibit at least 85% fiber recyclability and a stickies percentage of less than 15, preferably less than 5, as determined by the aforementioned Voluntary Standard. [Means for solving the problem]

[0012] The present disclosure relates to a paper-based backing layer.

[0013] The present disclosure provides: - the first layer, which is the paper layer; - A second layer, which is a barrier coating layer applied to one or both sides of the first layer. In a backing layer comprising: - 30 to 70% by weight of inorganic fillers, - 70 to 30% by weight of polymers with a glass transition temperature (Tg) between -35 and +15°C The backing layer is characterized by comprising:

[0014] The present disclosure also provides an adhesive tape comprising the above-described backing layer.

[0015] The backing layer of the present disclosure has passed the strict standards of the "Voluntary Standard For Repulping and Recycling Corrugated Fiberboard Treated to Improve Its Performance in the Presence of Water and Water Vapor" (revised August 16, 2013) issued by the American Corrugated Board Association (FBA). The backing layer exhibits advantageous fiber recyclability and stickies count, and is highly repulpable. The backing layer exhibits improved manufacturing efficiency and a reduced ecological footprint. This is therefore advantageous and helpful in improving the manufacturing efficiency and ecological footprint of conventional tapes, labels, and related products. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 shows a suitable backing layer for a single-sided adhesive tape. [Figure 2] FIG. 1 shows a suitable backing layer for double-sided adhesive tape. DETAILED DESCRIPTION OF THE INVENTION

[0017] definition Further aspects, features and advantages of the exemplary embodiments will become apparent from the following detailed description.

[0018] The patents, published applications, and scientific literature referred to herein establish the knowledge of those skilled in the art and are hereby incorporated by reference in their entirety to the same extent as if each was specifically and individually indicated to be incorporated by reference.

[0019] As used herein, in transitional phrases or claims, the terms "comprise(s)" and "comprising" should be construed as having an open-ended meaning. That is, these terms should be construed synonymously with the phrases "having at least" or "including at least." When used in the context of a process, the term "comprising" means that the process includes at least the recited steps, but may include additional steps. When used in the context of a composition, the term "comprising" means that the composition includes at least the recited features or components, but may also include additional features or components.

[0020] The terms "consists essentially of" or "consisting essentially of" have a partially exclusive meaning, i.e., they do not permit the inclusion of steps or features or components that substantially alter the essential characteristics of the method or composition, e.g., steps or features or components that significantly interfere with the desired properties of the compounds or compositions described herein, i.e., the method or composition is limited to the specified steps or materials and those that do not substantially affect the basic and novel characteristics of the method or composition. The terms "consists of" and "consists" are exclusive terminology, permitting only the inclusion of the recited steps or features or components.

[0021] As used herein, the singular forms "a," "an," and "the" also include the plural forms of the words to which they specifically refer, unless the context clearly dictates otherwise.

[0022] The terms "dissolved" or "substantially dissolved" as used herein refer to the solubilization of a solid in a solution. A solid can be considered "dissolved" or "substantially dissolved" in a solution if the resulting solution is clear or substantially clear.

[0023] As used herein, the recitation of a numerical range for a variable is intended to convey that the variable can be equal to any value within that range. Thus, for a variable that is inherently discrete, the variable may be equal to any integer value in that numerical range, including the end-points of the range. Similarly, for a variable that is inherently continuous, the variable may be equal to any real value in that numerical range, including the end-points of the range. By way of example, a variable described as having a value between 0 and 2 may be 0, 1, or 2 for a variable that is inherently discrete, or 0.0, 0.1, 0.01, 0.001, or any other real value for a variable that is inherently continuous.

[0024] In the specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0025] Unless otherwise defined, technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this specification pertains.

[0026] definition The present disclosure provides a backing layer, which is a stack of layers that acts as a support onto which layers can be applied, the resulting multi-layer stack having specific properties, each fulfilling a specific function, making the multi-layer stack suitable for use in a variety of fields.

[0027] The backing layer is paper-based.

[0028] The backing layer of the present disclosure comprises: - the first layer, which is the paper layer; - A second layer, which is a barrier coating layer applied to one or both sides of the first layer. the barrier coating layer comprising: - 30 to 70% by weight of inorganic fillers, - 70 to 30% by weight of polymers with a glass transition temperature (Tg) between -35 and +15°C The present invention is characterized by comprising:

[0029] The paper layer functions as a support layer or substrate layer, which may be referred to in the prior art as a paper support.

[0030] The barrier coating layer can be applied to both sides of the paper layer or to only one side of the paper layer. Preferably, it is applied to both sides of the paper layer. The barrier coating layer may be applied directly to the first paper layer. Preferably, it is applied directly to both sides of the paper layer.

[0031] The backing layer may include a primer layer applied to the second layer (i.e., the barrier coating layer), which acts as an intermediate layer between the barrier coating layer and another layer to ensure the stability of the layer stack.

[0032] In one embodiment, the primer layer may be present on only one side of the backing layer. The primer layer may be applied directly to the barrier coating layer on only one side of the backing layer. The release coating layer may be applied to a second layer (i.e., the barrier coating layer) of the backing layer opposite the primer layer. The release coating layer may be applied directly to said second layer. Thus, the release coating layer is present on only one side of the backing layer. The release coating layer ensures that the backing layer can be rolled up during manufacturing and unrolled to the desired length before use.

[0033] FIG. 1 shows a backing layer comprising a paper layer (1), a barrier coating layer (2), a primer layer (3) and a release coating layer (4).

[0034] In one embodiment, the backing layer may include a first layer that is a paper layer; a second layer that is a barrier coating layer applied directly to both sides of the paper layer; a primer layer applied directly to the second layer on only one side of the backing layer; and a release coating layer applied directly to the second layer of the backing layer opposite the primer layer. In one embodiment, the backing layer may be comprised of the layer sequences and laminates described above.

[0035] The primer layer can receive layers such as an adhesive layer, and the adhesive can be applied to only one side, forming a single-sided adhesive tape.

[0036] FIG. 2 shows a backing layer comprising a paper layer (1), two barrier coating layers (2), and two primer layers (3).

[0037] In one embodiment, a primer layer can be present on both sides of the second layer (i.e., the barrier coating layer). The primer layer can also be applied directly to the barrier coating layer on both sides of the backing layer. Thus, in one embodiment, the backing layer can include a first layer that is a paper layer; a second layer that is a barrier coating layer applied directly to both sides of the paper layer; and a primer layer applied directly to the second layer on both sides of the backing layer. In one embodiment, the backing layer can be comprised of the layer sequences and laminates described above.

[0038] The two primer layers can receive layers such as adhesive layers, and adhesive can be applied to both primer layers to form a double-sided adhesive tape.

[0039] The second layer (i.e., the barrier coating layer) contains 30 to 70 wt.% of the inorganic filler. The barrier coating layer may contain preferably 35 to 65 wt.%, more preferably 40 to 60 wt.%, and most preferably 45 to 55 wt.% of the inorganic filler.

[0040] The inorganic filler may be a hydrophilic filler. The inorganic filler may be selected from the group consisting of kaolinite, calcined kaolinite, calcium carbonate, precipitated calcium carbonate (PCC), ground calcium carbonate (GCC), talc, mica, clay, silica, precipitated silica, pyrogenic silica, titanium dioxide, or mixtures thereof. The barrier coating layer may preferably comprise kaolinite. The hydrophilic filler is typically not coated or chemically treated in any way.

[0041] The presence of inorganic fillers in the barrier coating layer in the aforementioned proportions has the advantage that the repulpability and stickies count of the backing layer are significantly improved. Without being bound by any particular theory, it is hypothesized that the presence of a significant amount of inorganic fillers, especially hydrophilic fillers, in the barrier coating layer allows water penetration into the layer during the recycling procedure and allows the polymeric components of the layer to be suspended in water.

[0042] The second layer (i.e., the barrier coating layer) comprises 70 to 30 wt. % of a polymer having a glass transition temperature (Tg) of -35 to +15°C. The mass percentage is calculated based on all components of the barrier coating layer in the dry, applied state. The barrier coating layer may comprise 65 to 35 wt. %, preferably 60 to 40 wt. %, and more preferably 55 to 45 wt. % of a polymer having a glass transition temperature (Tg) of -35 to +15°C.

[0043] The polymer may have a glass transition temperature (Tg) of -30 to +10°C, preferably -25 to +5°C. Glass transition temperature is measured according to DIN ISO 53765 (1994-03). Polymers with a Tg below zero degrees Celsius, especially significantly below zero degrees Celsius, are considered hard polymers that tend to be tacky. Polymers with a Tg above zero degrees Celsius tend not to be tacky. The present disclosure provides a backing layer comprising a polymer with a Tg below zero degrees Celsius that is tacky yet has a tack count of less than 5, thereby complying with the above voluntary standard as tested by Western Michigan University.

[0044] The polymer may be selected from the group consisting of carboxylated styrene-butadiene rubber, styrene butadiene-rubber, acrylate-based polymers, acrylonitrile butadiene rubber, natural rubber, polyvinyl acetate or mixtures thereof, with carboxylated styrene-butadiene rubber being preferred.

[0045] The barrier coating layer may contain 65 to 35 wt.%, preferably 60 to 40 wt.%, more preferably 55 to 45 wt.% of a carboxylated styrene-butadiene rubber having a Tg of -27 to -23°C.

[0046] The barrier coating layer may contain 65 to 35 wt.%, preferably 60 to 40 wt.%, more preferably 55 to 45 wt.% of a carboxylated styrene-butadiene rubber having a Tg of +3 to +7°C.

[0047] The barrier coating layer may contain an antifoaming agent. The antifoaming agent may be contained in an amount of 0 to 0.05 wt.%. When contained, the amount may be 0.05 wt.% or less, or 0.01 to 0.03 wt.%. The proportion is calculated based on the total mass of the barrier coating layer, and the total of the inorganic filler, polymer, and antifoaming agent is 100 wt.%.

[0048] The antifoaming agent may be selected from the group consisting of mineral oil-based, vegetable oil-based, and siloxane oil-based antifoaming agents.

[0049] In one embodiment, the barrier coating layer comprises the inorganic filler in the weight percentage, the polymer in the weight percentage, and the antifoaming agent in the weight percentage. In one embodiment, the barrier coating layer can consist of the aforementioned components in given weight percentages.

[0050] The barrier coating layer can consist essentially of the above components in given percentages, thereby not excluding the presence of impurities due to processing parameters or specifications of starting materials, as well as the presence of conventional additives in small mass percentages that do not substantially alter the technical properties, the intended effect described in this disclosure, and the usefulness of the barrier coating layer. To achieve the intended effect, the inorganic filler and polymer occupy a combined percentage of the barrier coating layer of at least 93%, preferably at least 95%, or even at least 97%.

[0051] The barrier coating layer may contain conventional additives such as crosslinkers, dispersants, wetting agents, thickeners, hydrophobizing or hydrophilizing agents in conventional amounts, for example, a minimum of 0.05, 0.1, or 0.25 wt.% to 3, 4, or 5 wt.%, When additives are present, the inorganic filler and polymer constitute a combined percentage of the barrier coating layer of at least 93%, preferably at least 95%, or even at least 97%.

[0052] The barrier coating layer is applied at a coating weight of 1 to 10 gsm, preferably 3 to 7 gsm.

[0053] The first layer of the backing layer of the present disclosure is a paper layer.

[0054] The paper layer may have an extensibility in the machine direction (MD) of 3 to 10%, preferably 5 to 8%, measured according to DIN EN ISO 1924-2 (2008).

[0055] The paper may have an elongation in the cross direction (CD) perpendicular to the machine direction (MD) of 5 to 15%, preferably 8 to 12%, as measured in accordance with DIN EN ISO 1924-2 (2008). The elongation value, particularly in the machine direction, allows for the use of backing layers in adhesive tapes and related applications. The elongation allows the backing layers to be used in various tape forms used for packaging or fastening. The elongation is maintained even after application of the layers described herein. The elongation of the final product may exceed the aforementioned elongation values, depending on the application of layers.

[0056] In addition, the paper used as the paper layer may be of high density and high size, so that the components of the barrier coating layer do not penetrate into the paper layer, or penetrate only to a very limited extent, and repulpability is maintained.

[0057] The paper layer may have a porosity measured as air resistance (Gurley) of 5 to 25, preferably 10 to 20 Gurley, measured according to ISO 5636-5 (2003).

[0058] The paper layer may have a water absorbency (Cobb 60) value of 20 to 40 gsm, preferably 25 to 35 gsm, measured according to Cobb 60 test method ISO 535 (2014).

[0059] The porosity and water absorption values ​​ensure that the components of the barrier coating layer do not penetrate into the paper layer, or penetrate only to a very limited extent, but that the paper layer remains repulpable. The paper layer may consist of paper that meets the aforementioned requirements, without other coatings or without any treatment, such as coatings other than treatments or coatings to reach the aforementioned technical properties.

[0060] The paper used in the paper layer may be selected from the group consisting of bleached or brown kraft paper, bleached or brown sack kraft paper, semi-stretchable kraft paper, semi-stretchable sack kraft paper, preferably semi-stretchable sack kraft paper.

[0061] The paper meets the air resistance (Gurley) and water absorbency (Cobb 60) requirements listed above, so that components of the barrier coating layer do not penetrate, or penetrate only to a very limited extent, into the paper layer, while the paper layer remains repulpable.

[0062] These papers have not undergone any additional treatments such as additional coatings, etc. The papers are used as purchased.

[0063] The paper used in the paper layer may have a basis weight of 40 to 100 gsm, or 40 to 80 gsm, preferably 50 to 70 gsm.

[0064] The backing layer may include a primer layer, which may be present on one or both sides of the second layer (i.e., barrier coating layer) as described above. The primer layer may comprise a polymer or polymer composition selected from the group consisting of styrene butadiene rubber, acrylate-based polymers, acrylonitrile butadiene rubber, polyvinyl acetate, natural rubber, vulcanized natural rubber, butyl acrylate; methacrylate-grafted natural rubber, carboxylated styrene butadiene rubber, and polyurethane.

[0065] The primer layer may comprise one polymer or a mixture of two or more polymers.

[0066] The primer layer may be a composition containing vulcanized natural rubber and butyl acrylate. The primer layer may be a composition containing methacrylate-grafted natural rubber and carboxylated styrene-butadiene rubber. The composition may contain methacrylate-grafted natural rubber and carboxylated styrene-butadiene rubber blended in a ratio of 80:20 to 95:05.

[0067] In some examples, the primer layer may include the same polymer or polymers as the barrier coating layer.

[0068] The subbing layer may be present at a coating weight of 0.1 to 3 gsm, preferably 0.5 to 2 gsm.

[0069] The release coating layer may be applied to the primer layer as described above. The composition of the release coating layer is well known in the art. For example, the release coating layer may comprise a composition comprising a polymer selected from the group consisting of hydrophilic acrylic or acrylate polymers; water-based vinyl acetate copolymer latexes.

[0070] The release coating layer may be applied to achieve a coating weight of 0.1 to 5 gsm, preferably 0.5 to 4 gsm, over the primer layer.

[0071] The total thickness of the backing layer, including the layers described herein, ranges from 60 to 150 micrometers. For example, a 90 g / m2 backing layer of the present disclosure has a thickness of 105 to 135 micrometers. A 70 g / m2 backing layer has a thickness of 70 to 100 micrometers.

[0072] The backing layer of the present disclosure exhibits a repulpability of greater than 85%, as measured based on repulping and recycling tests conducted at Western Michigan University in accordance with the above-mentioned voluntary standards. The backing layer of the present disclosure also exhibits a stickiness formation of less than 5 during papermaking. The test method demonstrates that a) cellulose fibers can be recycled at a high yield to form sheet paper, and b) the polymers used in particular to manufacture the backing layer can be easily separated from the cellulose fibers when used adhesive tapes or other products containing the backing layer of the present disclosure are subjected to paper recycling processes. Therefore, the backing layer of the present disclosure has high recyclability and repulpability.

[0073] The backing layer is suitable for a variety of applications such as adhesive tapes used in securing and packaging corrugated boxes, adhesive tapes applied to the inside of envelope flaps, and in the construction industry.

[0074] The backing layer is also suitable for print media, labels, binding tapes, carrier handle tapes, printed packaging tapes, promotional streamers, industrial packaging for light to medium heavy duty applications, and paper-based adhesive foils.

[0075] The backing layer is particularly suitable for single or double sided adhesive tapes, as shown in FIGS.

[0076] The present disclosure also provides an adhesive tape including the backing layer of the present disclosure. The adhesive tape includes an adhesive layer on the bottom primer layer, resulting in a single-sided adhesive tape. The adhesive tape includes adhesive layers on both primer layers, resulting in a double-sided adhesive tape. Adhesive layers are well known in the art. Any adhesive layer known in the art can be used in conjunction with the backing layer of the present disclosure. The advantageous properties of the backing layer provide an adhesive tape that is highly recyclable and repulpable.

[0077] The backing layer of the present disclosure is produced by sequentially coating the layers onto the paper layer at the coating weights described above. The components of the layers may be applied as dispersions or solutions or dry coatings using standard methods known in the art.

[0078] The barrier coating layer may be applied via an impregnation device, such as a water bath containing a polymer dispersion, through which the paper layer is passed. The impregnated layer may then be introduced into a pair of rolls to remove excess coating layer from the paper, which may then be dried. A primer layer and a release layer (if required) may then be applied by an air knife device. [Example]

[0079] material Paper layer: Unbleached, semi-stretchable bag kraft paper; basis weight 60 g / m², tensile strength: (MD) 5.3, (CD) 4.0; porosity (air resistance, Gurley) 18 s / 100 ml; water absorbency (Cobb60) 31 g / m² (60 s).

[0080] Barrier coating layer: An aqueous colloidal dispersion of carboxylated styrene-butadiene copolymer (49-51% solids) was prepared using Exopal L7063, a product of EOC Belgium NV, as a carboxylated styrene-butadiene rubber (SBR) with a Tg of +5 degrees Celsius.

[0081] Aqueous colloidal dispersions of carboxylated styrene-butadiene copolymers (48-50% solids) were prepared using Trinseo's Ligod I4086 binder, a carboxylated styrene-butadiene rubber (SBR) with a Tg of -25°C.

[0082] The product "Capim DG Slurry" was used for the kaolinite, and a slurry with a solid content of 70.5 (wt.%) was produced.

[0083] Release coating layer: A hydrophilic acrylic emulsion was prepared using Primal R-253 ER emulsion from The Dow Chemical Company at 40% solids, or Orgal KR250 from Organikkimya (40% solids).

[0084] Primer layer: 90% methacrylate-grafted natural rubber blended with 10% carboxylated styrene-butadiene rubber

[0085] method The glass transition temperature is determined in accordance with DIN ISO 53765 (1994-03). The extensibility is measured in accordance with DIN EN ISO 1924-2 (2008). The porosity of the paper is measured as air resistance (Gurley) according to ISO 5636-5 (2003). The water absorbency of paper (Cobb 60) is measured based on the Cobb 60 test method ISO 535 (2014).

[0086] Repulpability and recyclability are measured in accordance with the "Voluntary Standard For Repulping and Recycling Corrugated Fiberboard Treated to Improve Its Performance in the Presence of Water and Water Vapor" (revised August 16, 2013) published by the American Corrugated Board Association (FBA). The test was conducted at the Western Michigan University Paper Pilot Plant in the United States. The test method is to evaluate the repulpability and recyclability of moisture barrier treatments or coatings applied to liner or composite corrugated board with the goal of establishing a minimum threshold for moisture barrier treated or coated corrugated board intended and labeled as recyclable into new containerboard and other paper products. The test is described below. In this test, the following terms have the following meanings: - Fiber-on-fiber yield is the amount of fiber remaining after a processing operation, expressed as a percentage of the fiber present in the material under test. - Recyclable means post-consumer paper, including in-plant and post-consumer waste paper and paperboard, that can be converted into new paper or paperboard using the processes defined in this standard. - Repulpable means that the test material can be subjected to the operation of rewetting and fiberization for subsequent sheet formation using the process defined in this standard. - Handmade sheets are sheets made from a suspension of fibre in water by manipulation, so that each sheet is formed individually by discharging the pulp suspension onto a fixed sheet mould.

[0087] Preliminary analysis: Determine the moisture content of the treated cardboard samples before starting the test protocol.

[0088] Part 1: Repulpability The treated cardboard is repulped at 100% input in a modified Waring blender and British disintegrator in water at pH 7 (±0.5 pH) maintained at 125°F (±10°C) according to the procedure outlined in the Repulping Test Procedure below. The pulped material is separated on a screen with slots of 0.010 inches or less to determine fiber recovery as a percentage of the amount of fiber input.

[0089] The fiber yield from the repulping test must be at least 80% based on the total mass, or 85% based on the oven-dry fiber input to the pulper.

[0090] Part 2: Recyclability A minimum of 20% treated cardboard and the remainder of the same untreated cardboard are mixed in a laboratory-scale pulper at pH 7 (±0.5 pH) and 125°F (±10°F). This is the recyclability test sample. As a control, a 100% charge of the same untreated cardboard is also pulped using the same conditions. Each pulp material is passed (sequentially) through a pressure screen with a basket having 0.062-inch holes, an identical or similar screen with a basket having 0.010-inch slots, and an inverse centrifuge under the conditions specified in the recyclability test procedure below.

[0091] Handsheets (3.0 grams) are made from the final (cleaner) pass. For each batch tested, the handsheets are compressed, baked, and tested for product performance characteristics. Appearance testing is performed according to the procedures outlined in Appendix B. The final sheets should be 0.4 mm thick, averaged across three sheets. 2 The number of spots shall not exceed 15 or be more than 30% greater than the control over the area above. Detailed procedures for recyclability are described in the Recyclability Test Procedure below.

[0092] Repulping Test Procedure the purpose To determine the repulpability of the cardboard. (Note that the repulping test must be performed at least twice on the treated cardboard. The sample must pass two out of three tests.) Device Specimen cutting device Balance (0.01 gram accuracy) Waring blender (with special blade, see Figure 1) ·Hot water 125°F ± 10°F (52°C ± 5°C) British-made pulp disintegrator (Pulp Evaluation Standard Equipment No. 270) Open flat screen 10 cut (0.010 inch), Valley or Somerville screen, etc. Aluminum weighing pan Laboratory oven 221°F (105°C)

[0093] Test Piece Inspection 1. Cut the cardboard into 1 1 / 4 inch (31.8 mm) x 4 inch (102 mm) strips. 2. Weigh out 0.055 pounds (25 grams) of cardboard. 3. Place the sample in 1500 ml of water at 125°F ± 10°F (52°C ± 3°C). 4. Preheat the blender and British disintegrator to 125°F ± 10°F. 5. Blend in a 1-gallon Waring blender (equipped with a special blade) on low speed (15,000 rpm) for 4 minutes. 6. Rinse all fibre from the blender with 500ml of warm water. 7. Deflake in a British disintegrator (total volume 2000ml) at 3000 rpm for 5 minutes. 8. Run for 20 minutes on a 0.010 inch (0.254 mm) slotted open flat screen while maintaining a 1 inch head of water; collect passing and failing samples in an aluminum weighing pan. 9. Dry in a laboratory oven at 221°F (105°C) for 12 hours (± 4 hours). 10. Weigh the pan and record the net mass of the pass, fail, and total pass and fail items.

[0094] calculation % Rejected = (Net Rejected x 100) / (Net Accepted + Net Rejected) The value obtained indicates the percentage of repulpability of the fiber.

[0095] Recyclability Test Procedure Note: Both the control sample and the treated and untreated test material samples must be tested at least twice and must pass two out of three tests.

[0096] 1. Obtain a sample of treated cardboard for evaluation. From this sample, select a sufficient amount of material for testing. The selection should be as representative as possible of the material as a whole. Also obtain a sufficient amount of untreated cardboard to carry out the protocol. The choice of input amount will depend on the capacity of the pilot plant pulper used. Pulping should be carried out at a 3% consistency or the consistency recommended by the pulping equipment manufacturer.

[0097] 2. Determine moisture content [TAPPI T 412]. Steps 3 through 9 are performed twice - once with the untreated "control" sample and once with the "recyclability test sample."

[0098] 3. Use the selected sample material of any convenient size but not less than 1 x 1 square inch. Raise the apparatus to 125°F (±10°C). Adjust the pH of the charge so that after pulping it equals pH 7 (±0.5 pH). Raise the pulper temperature to 125°F (±10°C). Charge the pulper and pulp for 15 minutes while maintaining at 125°F (±10°C).

[0099] 4. Repeat step 3 until you have enough material for the following step. Maintain the pulp temperature at 125°F (±10°) until it is used in step 5.

[0100] 5. If necessary, combine pulp from several batches and dilute to the manufacturer's recommended consistency with water heated to 125°F (±10°). Adjust the pH to 7 (±0.5 pH). Preheat a screen with 0.0625 inch holes to 125°F (±10°) and maintain temperature throughout this screening step. Pass the pulp sample through the preheated screen at a volumetric reject rate of 10% of the feed rate, or an appropriate volumetric rejection rate based on the manufacturer's specifications or recommendations.

[0101] 6. For products that pass Step 5, repeat the procedure in Step 5 using a screen basket with 0.010 inch slots, again maintaining temperature, consistency, and 10% rejection, or rejection based on manufacturer's specifications.

[0102] 7. Pass the product that passes Step 6 through a lightweight reverse centrifugal cleaner, maintaining a temperature of 125°F (±10°C), consistency, and pressure differential specified for the cleaner used. Determine and report the volumetric removal rate.

[0103] 8. From the accepted product from step 7, form handsheets according to TAPPI T 205 under the following conditions: - The slurry should be vigorously agitated (without altering the fiber distribution in the slurry) and maintained at 125°F (±10°) and pH 7 (±0.5 pH). - Dry the sheets in a surface dryer maintained at 250-275°F with a moisture content limit of 7%. - Readjust to TAPPI standard conditions before testing.

[0104] Handsheet preparation for stickies / spot count testing: 1. Connect the Carver press and preheat the top and bottom platens to 350°F. 2. Dilute the test stock solution to approximately 1% consistency. 3. Form a 500ml check sheet and allow to dry. Wipe off excess water using two pieces of blotting paper, a round metal plate, and a roller. Dry on new blotting paper using a speed dryer. 4. Weigh the handmade sheet and mark its identification and dry weight on the top side (not the wire side) of the handmade sheet. 5. Calculate the amount of slurry to use for the test sheet using the following formula: 2.00 grams ÷ dry sheet mass × 500 = mls of slurry used for test sheet. 6. Use the calculated amount of slurry to form three handmade sheets for testing. 7. Place the sheets on absorbent paper and dry in a speed dryer, then write their identifying information on the top side of each sheet. 8. Remove the test sheet from the speed dryer (drying time 3-5 minutes). 9. Place each test sheet between the filter paper and the blotter paper in the following configuration (bottom to top): Blotting paper Filter adhesive sheet Filter Blotting paper 10. Stack the test sheets on top of each other and press in a preheated Carver press at 350°F and 500 psi for 5 minutes. Observe that the pressure gauge remains at 500 psi. 11. Remove the test sheets from the Carver press and weigh each sheet. Record the dry mass of each sheet 12. Using any suitable analysis tool, such as a TAPPI T-537 dirt count estimator or the image analysis systems referenced in TAPPI T-277 and TAPPI T-563, measure the dirt count within an area of ​​0.4 mm 2 Count the spots on the handmade sheet above.

[0105] This number represents the number of spots, also called the "sticky count" or "sticky number."

[0106] Example A backing layer according to the present disclosure was prepared as follows: The barrier coating layer is applied to the paper layer through a water bath containing a polymer dispersion. The temperature of the water bath is generally room temperature (15-40°C). The impregnated layer can then be introduced into a pair of rolls to remove excess coating from the paper. It can then be dried at 50-220°C. A primer layer and a release layer (if required) can then be applied at room temperature with an air knife device.

[0107] Example 1 As above, unbleached semi-stretchable sack kraft paper of 60 gsm basis weight was used as the paper layer.

[0108] The paper layer was coated on both sides with a composition containing 50% carboxylated styrene-butadiene rubber (SBR) with a Tg of -25°C and 50% kaolinite to provide a barrier coating layer. The coating weight was 5 gsm. In this example, soft SBR was used.

[0109] One side of the resulting layer stack was coated with a hydrophilic acrylic dispersion (Primal R253 / Orgal KR250) at a coating weight of 2 gsm to provide a release coating layer.

[0110] When the resulting backing layer was subjected to the Western Michigan University Repulping and Recycling Test Method, fiber recyclability yields of 92.5% and 94.1% (test run twice) were obtained. Since the values ​​were above 85%, the samples passed the test method.

[0111] For the stickies test, one stickie was observed per handmade sheet, which is less than the target of five stickies, so the sample passed the test method.

[0112] Example 2 Unbleached semi-stretchable sack kraft paper with a basis weight of 60 gsm was used as the paper layer.

[0113] The paper layer was coated on both sides with a composition containing 50% carboxylated styrene-butadiene rubber (SBR) with a Tg of +5°C and 50% kaolinite to provide a barrier coating layer. The coating weight was 5 gsm. In this example, hard SBR was used.

[0114] One side of the resulting layer stack was coated with a hydrophilic acrylic dispersion (Primal R253 / Orgal KR250) at a coating weight of 2 gsm to provide a release coating layer.

[0115] When the resulting backing layer was subjected to the Western Michigan University Repulping and Recycling Test Method, fiber recyclability yields of 95.8% and 97.5% (test run twice) were obtained. Since the values ​​were above 85%, the samples passed the test method.

[0116] For the stickies test, 1.67 stickies were observed per handmade sheet, which is less than the target of 5 stickies, so the sample passed the test method.

[0117] (Comparative Example) Unbleached semi-stretchable sack kraft paper with a basis weight of 60 gsm was used as the paper layer.

[0118] The paper layer was coated on both sides with a composition containing 50% carboxylated styrene-butadiene rubber (SBR) with a Tg of -25°C to provide a barrier coating layer, with a coating weight of 5 gsm.

[0119] One side of the resulting layer stack was coated with a hydrophilic acrylic dispersion (Primal R253 / Orgal KR250) at a coating weight of 2 gsm to provide a release coating layer.

[0120] The opposite side of the layer stack was coated with a dispersion containing 90% methacrylate grafted natural rubber and 10% carboxylated styrene-butadiene rubber at a coating weight of 1 gsm to provide a primer layer.

[0121] When the resulting backing layer was subjected to the Western Michigan University Repulping and Recycling Test Method, fiber recyclability yields of 65.9% and 69.2% (test run twice) were obtained. Because the values ​​were below 85%, the samples failed the test method.

[0122] For the stickies test, over 100 stickies were observed per handmade sheet. This observation exceeded the target of 5 stickies, so the sample failed this test method.

[0123] Embodiment Section 1. - The first layer, which is the paper layer; - A second layer, which is a barrier coating layer applied to one or both sides of the first layer. In a backing layer comprising the barrier coating layer, - 30 to 70% by weight of inorganic fillers, - 70 to 30% by weight of polymers with a glass transition temperature (Tg) between -35 and +15°C A backing layer comprising:

[0124] 2. The backing layer of claim 1, comprising a primer layer applied to a second layer that is a barrier coating layer, the primer layer being present on only one side of the backing layer.

[0125] 3. The backing layer of claim 1, comprising a primer layer applied to the second layer, which is a barrier coating layer, the primer layers being present on both sides of the backing layer.

[0126] 4. The backing layer of claim 2, comprising a release coating layer applied to a second layer that is a barrier coating layer, the release coating layer being present on only one side of the backing layer.

[0127] 5. A backing layer according to any one of claims 1 to 4, characterized in that the barrier coating layer contains 35 to 65 wt.%, preferably 40 to 60 wt.%, more preferably 45 to 55 wt.% of inorganic filler.

[0128] 6. A backing layer according to any one of claims 1 to 5, characterized in that the barrier coating layer comprises 65 to 35 wt.%, preferably 60 to 40 wt.%, more preferably 55 to 45 wt.% of a polymer having a glass transition temperature (Tg) of -35 to +15°C.

[0129] 7. A backing layer according to any one of claims 1 to 6, characterized in that the polymer has a glass transition temperature (Tg) of -30 to +10°C, preferably -25 to +5°C.

[0130] 8. A backing layer according to any one of claims 1 to 7, characterized in that the barrier coating layer contains 0 to 0.05 wt.% of an antifoaming agent.

[0131] 9. The backing layer according to claim 8, wherein the barrier coating layer contains 0.01 to 0.03 wt.% of an antifoaming agent.

[0132] 10. A backing layer according to claim 8 or 9, characterized in that the antifoaming agent is selected from the group consisting of mineral oil-based, vegetable oil-based, and siloxane oil-based antifoaming agents.

[0133] 11. A backing layer according to any one of claims 1 to 10, characterized in that the first layer, which is a paper layer, has an extensibility in the machine direction (MD) of 3 to 10%, preferably 5 to 8%, the extensibility being measured in accordance with DIN EN ISO 1924-2.

[0134] 12. A backing layer according to any one of claims 1 to 11, characterized in that the first layer, which is a paper layer, has an extensibility of 5 to 15%, preferably 8 to 12%, in the cross direction (CD) perpendicular to the machine direction (MD).

[0135] 13. A backing layer according to any one of claims 1 to 12, characterized in that the first layer, which is a paper layer, has a porosity, measured as air resistance (Gurley), of 5 to 25, preferably 10 to 20 Gurley, measured according to ISO 5636-5.

[0136] 14. A backing layer according to any one of claims 1 to 13, characterized in that the first layer, which is a paper layer, has a water absorbency (Cobb 60) value, measured according to Cobb 60 test method ISO 535, of 20 to 40 gsm, preferably 25 to 35 gsm.

[0137] 15. A backing layer according to any one of claims 1 to 14, characterized in that the first paper layer comprises a paper selected from the group consisting of bleached or brown kraft paper, bleached or brown sack kraft paper, semi-stretchable kraft paper, semi-stretchable sack kraft paper, preferably semi-stretchable sack kraft paper.

[0138] 16. A backing layer according to any one of claims 1 to 15, characterized in that the first layer, which is a paper layer, comprises paper having a basis weight of 40 to 80 gsm, preferably 50 to 70 gsm.

[0139] 17. A backing layer according to any one of claims 1 to 16, characterized in that the second layer, which is a barrier coating layer, comprises an inorganic filler selected from the group consisting of kaolinite, calcined kaolinite, calcium carbonate, precipitated calcium carbonate (PCC), ground calcium carbonate (GCC), talc, mica, clay, silica, precipitated silica, pyrogenic silica, titanium dioxide, or mixtures thereof.

[0140] 18. A backing layer according to any one of claims 1 to 16, characterized in that the second layer, which is a barrier coating layer, comprises kaolinite.

[0141] 19. A backing layer according to any one of claims 1 to 18, characterized in that the second layer, which is a barrier coating layer, comprises a polymer selected from the group consisting of carboxylated styrene-butadiene rubber, styrene butadiene rubber, acrylate-based polymers, acrylonitrile butadiene rubber, natural rubber, polyvinyl acetate or mixtures thereof, with carboxylated styrene-butadiene rubber being preferred.

[0142] 20. A backing layer according to any one of claims 1 to 18, characterized in that the second layer, which is a barrier coating layer, comprises a carboxylated styrene-butadiene rubber having a Tg of -27 to -23°C.

[0143] 21. A backing layer according to any one of claims 1 to 18, characterized in that the second layer, which is a barrier coating layer, comprises a carboxylated styrene-butadiene rubber having a Tg of +3 to +7°C.

[0144] 22. A backing layer according to any one of claims 1 to 21, characterized in that the second layer, which is a barrier coating layer, is present at a coating weight of 1 to 10 gsm, preferably 3 to 7 gsm.

[0145] 23. A backing layer according to any one of claims 2 to 22, characterized in that the primer layer comprises a polymer or polymer composition selected from the group consisting of styrene butadiene rubber, acrylate polymers, acrylonitrile butadiene rubber, polyvinyl acetate, natural rubber, vulcanized natural rubber, butyl acrylate; methacrylate-grafted natural rubber, carboxylated styrene butadiene rubber, and polyurethane.

[0146] 24. The backing layer of claim 23, wherein the primer layer comprises a composition of methacrylate-grafted natural rubber and carboxylated styrene butadiene rubber in a ratio of 80:20 to 95:05.

[0147] 25. A backing layer according to any one of claims 2 to 14, characterized in that the primer layer is present at a coating weight of 0.1 to 3 gsm, preferably 0.5 to 2 gsm.

[0148] 26. A backing layer according to any one of claims 4 to 25, characterized in that the release coating layer comprises a composition comprising a polymer selected from the group consisting of: hydrophilic acrylic or acrylate polymers; and water-based vinyl acetate copolymer latexes.

[0149] 27. A backing layer according to any one of claims 4 to 26, characterized in that the release coating layer is present at a coating weight of 0.1 to 5 gsm, preferably 0.5 to 4 gsm.

[0150] 28. The backing layer of any one of claims 1 to 27, characterized in that it has a repulpability of greater than 85% as measured according to the Western Michigan University Repulpability and Recycling Test Method.

[0151] 29. A backing layer according to any one of claims 1 to 28, characterized in that it has a stickiness formation in papermaking of less than 5.

[0152] 30. A backing layer according to any one of claims 1 to 29, characterized in that it is suitable for adhesive tapes.

[0153] 31. An adhesive tape comprising a backing layer according to any one of claims 1 to 30.

Claims

1. - a first layer which is a paper layer, a second layer which is a barrier coating layer applied to one or both sides of said first layer; a backing layer comprising: - 30% to 70% by weight of inorganic fillers, - 70% to 30% by weight of a polymer having a glass transition temperature (Tg) of -35°C to +15°C A backing layer comprising:

2. 10. The backing layer of claim 1, comprising a primer layer applied to the second layer, which is a barrier coating layer, the primer layer being present on only one side of the backing layer.

3. 10. The backing layer of claim 1, comprising a primer layer applied to the second layer, the second layer being a barrier coating layer, the primer layers being present on both sides of the backing layer.

4. 3. The backing layer of claim 2, comprising a release coating layer applied to the second layer, which is a barrier coating layer, the release coating layer being present on only one side of the backing layer.

5. 5. The backing layer according to claim 1, wherein the barrier coating layer comprises 35 wt. % to 65 wt. %, preferably 40 wt. % to 60 wt. %, more preferably 45 wt. % to 55 wt. % of inorganic filler.

6. 6. The backing layer according to any one of claims 1 to 5, characterized in that the barrier coating layer comprises 65 wt. % to 35 wt. %, preferably 60 wt. % to 40 wt. %, more preferably 55 wt. % to 45 wt. % of a polymer having a glass transition temperature (Tg) of -35°C to +15°C.

7. 7. The backing layer according to claim 1, wherein the first layer, which is a paper layer, has an extensibility in the machine direction (MD) of 3% to 10%, preferably 5% to 8%, the extensibility being measured according to DIN EN ISO 1924-2.

8. 8. The backing layer according to claim 1, wherein the first layer is a paper layer and has an extensibility in a cross direction (CD) perpendicular to the machine direction (MD) of 5% to 15%, preferably 8% to 12%.

9. 9. A backing layer according to any one of claims 1 to 8, characterized in that the first layer, which is a paper layer, comprises paper having a basis weight of 40 gsm to 80 gsm, preferably 50 gsm to 70 gsm.

10. 10. The backing layer of claim 1, wherein the second layer, which is a barrier coating layer, comprises an inorganic filler selected from the group consisting of kaolinite, calcined kaolinite, calcium carbonate, precipitated calcium carbonate (PCC), ground calcium carbonate (GCC), talc, mica, clay, silica, precipitated silica, pyrogenic silica, titanium dioxide, or mixtures thereof.

11. 11. A backing layer according to any one of claims 1 to 10, characterised in that the second layer, which is a barrier coating layer, is present at a coating weight of from 1 gsm to 10 gsm, preferably from 3 gsm to 7 gsm.

12. 12. The backing layer of any one of claims 1 to 11, characterized in that it has a repulpability of greater than 85% as measured according to Western Michigan University's Repulping and Recycling Test Method.

13. 13. The backing layer of any one of claims 1 to 12, characterized in that it has a stickies formation in papermaking of less than 15 (also claimed as less than 1.10 and less than 2.5).

14. 14. The backing layer of claim 13, characterized in that it has a stickies formation in papermaking of less than 10.

15. 14. The backing layer of claim 13, characterized in that it has a stickies formation in papermaking of less than 5.

16. 16. A backing layer according to any one of claims 1 to 15, characterized in that it is suitable for adhesive tapes.

17. An adhesive tape comprising a backing layer according to any one of claims 1 to 16.

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