Paper insert with improved wet strength

Abstract

An interleaf for a glass sheet includes a substrate and a coating material deposited on the substrate, wherein the coating material includes a dispersion medium and a wet strength additive.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 783396, filed April 4, 2025, pursuant to 35 USC § 119, the contents of which are based and are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates generally to paper inserts, and more specifically to paper inserts having improved wet strength. Background Technology

[0004] In the packaging and transportation of glass panels (such as those used in display applications), insert materials (such as insert paper) are typically inserted between the glass panels to help protect them from damage. In addition to providing physical protection, insert materials are also designed to minimize contaminants transferred to the glass surface. Furthermore, such insert materials should not impart undesirable static charges to the glass or adhere undesirably to the glass surface. Additionally, such materials should maintain their mechanical integrity and perform well over time in various environments, such as under different temperature and / or humidity conditions. Insert materials remain needed to meet these and other requirements in a cost-effective manner. Summary of the Invention

[0005] The embodiments disclosed herein include inserts comprising a paper substrate having a first primary surface and an opposite second primary surface. The insert also includes a coating material deposited on at least one of the first primary surface or the second primary surface. The coating material includes a dispersion medium and a wet strength additive.

[0006] Additionally, the embodiments disclosed herein include a method for packaging glass sheets, the method comprising positioning two or more glass sheets in a packaging apparatus and placing inserts between adjacent glass sheets. The inserts comprise a paper substrate including a first main surface and an opposite second main surface. The inserts also include a coating material deposited on at least one of the first main surface or the second main surface. The coating material comprises a dispersion medium and a wet strength additive.

[0007] Further features and advantages of the embodiments disclosed herein will be set forth in the following detailed description, and will be apparent in part to those skilled in the art from the description or to be recognized by practice of the disclosed embodiments as described herein (including the following detailed description, claims and drawings).

[0008] It should be understood that the foregoing general description and the following detailed description present embodiments and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed embodiments. Drawings are included to provide further understanding; the drawings are incorporated in and form a part of this specification. The drawings illustrate various embodiments of this disclosure and, together with the description, serve to explain their principles and operation. Attached Figure Description

[0009] Figure 1 This is a side perspective view of an exemplary packaging device according to embodiments disclosed herein;

[0010] Figure 2 This is a side perspective view of a plurality of glass plates and inserts disposed between adjacent glass plates in an exemplary packaging device according to embodiments disclosed herein;

[0011] Figure 3 This is a perspective view of an exemplary glass plate according to the embodiments disclosed herein;

[0012] Figure 4 This is a perspective view of an exemplary insert according to the embodiments disclosed herein;

[0013] Figure 5 This is an exploded cross-sectional view of a portion of an exemplary insert according to embodiments disclosed herein;

[0014] Figure 6 This is a schematic side view of an insert coating method according to embodiments disclosed herein;

[0015] Figure 7 This is a graph showing the change in fracture energy with the presence of wet strength additives in the coating material formulation according to the embodiments disclosed herein;

[0016] Figure 8 and 9 This is a graph showing the particle density on the main surface of a glass plate according to embodiments disclosed herein; and

[0017] Figure 10 This is a graph showing the water contact angle on the main surface of a glass plate according to an embodiment disclosed herein. Detailed Implementation

[0018] Reference will now be made in detail to the presently preferred embodiments of this disclosure, examples of which are illustrated in the accompanying drawings. Where possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. However, this disclosure may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0019] In this document, a range may be expressed as from “about” a specific value and / or to “about” another specific value. Another embodiment of expressing such a range includes from one specific value and / or to another specific value. Similarly, when a value is expressed as an approximation, for example by using the antecedent “about,” it should be understood that a specific value forms another embodiment. It should be further understood that the endpoints of each range are significant relative to and independent of the other endpoint.

[0020] As used herein, directional terms (e.g., up, down, right, left, front, back, top, bottom) refer only to the descriptions in the accompanying drawings and are not intended to imply absolute orientation.

[0021] Unless otherwise expressly stated, it is never intended to interpret any method set forth herein as requiring its steps to be performed in a particular order, nor is it intended to require any particular orientation of any device. Therefore, it is never intended to infer any order or orientation in any respect where a method claim does not actually describe the order in which its steps are followed, or where any device claim does not actually describe the order or orientation of individual components, or where the claims or description do not otherwise specifically specify that the steps are limited to a particular order, or where a particular order or orientation of the components of the device is not described. This applies to any possible non-expressive basis for interpretation, including: logical questions relating to the arrangement of steps, the flow of operations, the order of components, or the orientation of components; simple meanings derived from grammatical organization or punctuation; and the number or type of embodiments described in the description.

[0022] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” include plural indicators. Thus, for example, unless the context clearly indicates otherwise, a reference to a “a” or “an” component includes an aspect having two or more such components.

[0023] As used herein, the term “water-soluble” refers to a substance that can be dissolved independently in water (e.g., at least 25 mg of solute per milliliter of water at 25°C).

[0024] As used herein, the term “water insoluble” refers to a substance that is least soluble or insoluble in water on its own (e.g., less than 0.1 mg of solute per milliliter of water at 25°C).

[0025] As used herein, the term "surfactant" refers to a substance that tends to reduce the surface tension of the solvent in which it dissolves.

[0026] As used in this article, the term "defoamer" refers to a substance that tends to reduce or inhibit the formation of foam in a solution.

[0027] As used herein, the term "wet strength additive" refers to an additive present in a coating material that has the ability to increase the breaking energy of wet paper coated with the coating material by at least 25% (according to the wet tensile test method described herein) compared to the breaking energy of wet paper in any coating material without a wet strength additive.

[0028] As used herein, the term “mechanical pulping paper” refers to paper produced by mechanically manipulating (e.g., grinding, etc.) paper precursor materials (e.g., wood and / or other lignocellulosic materials, etc.) without extensive chemical or thermal processing steps.

[0029] As used herein, the term "thermochemical pulping paper" refers to paper produced by a process that includes chemical and / or thermal processing steps.

[0030] As used herein, the term "lignin" refers to a cross-linked phenolic biopolymer with a weight-average molecular weight of at least about 5,000 g / mol.

[0031] As used herein, the term "polysaccharide" refers to a polymeric carbohydrate having monosaccharide units linked by glycosidic bonds. Examples include cellulose, amylose, dextran, xylan, mannan, arabinogalactan, and galactan.

[0032] Figure 1 A side perspective view of an exemplary packaging apparatus 100 according to embodiments disclosed herein is shown. The packaging apparatus 100 includes a cover 102, a support member 104, a base 106, a tray 108, and at least one support column 110. The packaging apparatus 100 is configured to surround a plurality of glass plates positioned therein.

[0033] In some exemplary embodiments, the cover 102 may comprise metal, polymer, polymer composite material, and / or metal / polymer laminate. In some exemplary embodiments, the support member 104, base 106, tray 108, and / or pillar 110 may comprise metal (such as aluminum or stainless steel) or polymer composite material.

[0034] Figure 2 A side perspective view is shown of a plurality of glass plates 10 and inserts 20 disposed between adjacent glass plates 10 in an exemplary packaging apparatus 100 according to embodiments disclosed herein. The glass plates 10 and inserts 20 are positioned on a cushioning member 112, which in turn is positioned above a base 106, wherein the cushioning member 112 can be adhered to the base 106 with a suitable adhesive. The cushioning member 112 may, for example, comprise an elastic polymer material, such as a material comprising an ethylene-propylene-diene terpolymer.

[0035] Figure 3A perspective view of an exemplary glass plate 10 according to an embodiment disclosed herein is shown. The glass plate 10 has a first main surface 12, an opposite second main surface 14, and an edge surface 16, the second main surface extending in a direction generally parallel to the first main surface 12 (on the side of the glass plate 10 opposite to the first main surface 12), and the edge surface extending between the first main surface 12 and the second main surface 14 and in a direction generally perpendicular to the first main surface 12 and the second main surface 14.

[0036] Glass plate 10 may comprise various glass compositions. For example, the embodiments disclosed herein include those in which glass plate 10 comprises an alkali-free glass composition comprising 58-65 wt% SiO2, 14-20 wt% Al2O3, 8-12 wt% B2O3, 1-3 wt% MgO, 5-10 wt% CaO, and 0.5-2 wt% SrO. Glass plate 10 may also comprise an alkali-free glass composition comprising 58-65 wt% SiO2, 16-22 wt% Al2O3, 1-5 wt% B2O3, 1-4 wt% MgO, 2-6 wt% CaO, 1-4 wt% SrO, and 5-10 wt% BaO. Additionally, the glass plate 10 may comprise an alkali-free glass composition comprising 57-61 wt% SiO2, 17-21 wt% Al2O3, 5-8 wt% B2O3, 1-5 wt% MgO, 3-9 wt% CaO, 0-6 wt% SrO, and 0-7 wt% BaO. The glass plate 10 may also comprise an alkali-containing glass composition comprising 55-72 wt% SiO2, 12-24 wt% Al2O3, 10-18 wt% Na2O, 0-10 wt% B2O3, 0-5 wt% K2O, 0-5 wt% MgO, and 0-5 wt% CaO. In some embodiments, the alkali-containing glass composition may further comprise 1-5 wt% K2O and 1-5 wt% MgO.

[0037] In some exemplary embodiments, the thickness of the glass plate 10 is less than about 1 millimeter, such as a thickness ranging from about 0.1 millimeter to about 1 millimeter, including about 0.2 millimeter to about 0.8 millimeter, and further including about 0.3 millimeter to about 0.7 millimeter, including about 0.5 millimeter.

[0038] Figure 4A perspective view of an exemplary insert 20 according to an embodiment disclosed herein is shown. The insert 20 has a first main surface 22 and an opposite second main surface 24 extending in a direction generally parallel to the first main surface 22 (on the side of the insert 20 opposite to the first main surface 22).

[0039] Figure 5 An exploded cross-sectional view of a portion of an exemplary insert 20 according to an embodiment disclosed herein is shown. The insert 20 has a first main surface 22 and an opposite second main surface 24 extending in a direction generally parallel to the first main surface 22 (on the side of the insert 20 opposite to the first main surface 22). The insert 20 includes a substrate 30 comprising a first main surface 32 and an opposite second main surface 34 extending in a direction generally parallel to the first main surface 32. The insert 20 also includes a coating material 40 deposited on each of the first main surface 32 and the second main surface 34 of the substrate 30.

[0040] In some exemplary embodiments, substrate 30 comprises paper. In some exemplary embodiments, substrate 30 is substantially composed of paper. In some exemplary embodiments, substrate 30 comprises or is substantially composed of thermochemically pulped paper. In some exemplary embodiments, substrate 30 comprises or is substantially composed of mechanically pulped paper. Such embodiments include those in which the paper comprises at least 60% by weight of polysaccharide content and at least 5% by weight of total lignin content (e.g., 60% to 95% by weight of polysaccharide content and 5% to 40% by weight of total lignin content).

[0041] The embodiments disclosed herein include embodiments in which the coating material 40 comprises a dispersion medium and a wet strength additive. Such embodiments include those in which the coating material 40 is formulated into an aqueous dispersion (e.g., a water-based dispersion) comprising a dispersion medium and a wet strength additive prior to application or deposition onto the insert 20. Such embodiments also include those in which, based on the total weight of the aqueous dispersion, the coating material 40 deposited on the insert 20 comprises 5 wt% to 40 wt% (e.g., 10 wt% to 30 wt%, and further, 15 wt% to 25 wt%, including about 20 wt%) of dispersion medium and 0.2 wt% to 4 wt% (e.g., 0.5 wt% to 2 wt%, and further, 0.8 wt% to 1.5 wt%, including about 1 wt%) of wet strength additive.

[0042] In some exemplary embodiments, the dispersion medium comprises at least one of the following: polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylamide (PAAm), polyethylene glycol (PEG), hydroxypropyl methylcellulose (HPMC), poly-4-styrene sulfonate, and / or polydiallyl dimethylammonium chloride. In some exemplary embodiments, the dispersion medium comprises PVA. In some exemplary embodiments, the dispersion medium is substantially composed of PVA.

[0043] In some exemplary embodiments, the wet strength additive comprises starch. For example, the wet strength additive may comprise at least one of the following: corn starch, pea starch, rice starch, potato starch, or wheat starch.

[0044] The embodiments disclosed herein include those in which the coating material 40 further comprises at least one of a surfactant and / or a defoamer. For example, the coating material 40 may contain at least one defoamer, which may be water-insoluble or water-soluble, such as a water-insoluble or water-soluble alcohol ethoxylate. Exemplary water-insoluble alcohol ethoxylates include, but are not limited to, Tergitol, which is available from Dow Chemical. ® 15-S-3. Exemplary water-soluble alcohol ethoxylates include, but are not limited to, Tergitol, which is available from Dow Chemical Company. ® 15-S-9 or Tergitol ® 17-R-4, and Surfynol available from Evonik. ® 465 or Surfynol ® 420. Other water-insoluble defoamers include, but are not limited to, Surfynol, which is available from Evonik. ® MD20.

[0045] Such surfactants and / or defoamers may be incorporated into the aqueous dispersion described above in an amount ranging from 0.1 wt% to 2 wt% (e.g., 0.2 wt% to 1 wt%, and further such as 0.3 wt% to 0.6 wt%, including about 0.4 wt%) based on the total weight of the aqueous dispersion.

[0046] For example, the embodiments disclosed herein include those in which the coating material 40 is formulated as an aqueous dispersion, the aqueous dispersion comprising, based on the total weight of the aqueous dispersion, 60 wt% to 90 wt% water, 10 wt% to 30 wt% dispersion medium, and 0.5 wt% to 3 wt% wet strength additive, wherein the coating material 40 may additionally comprise 0.2 wt% to 1 wt% surfactant and / or defoamer. Such embodiments include, based on the total weight of the aqueous dispersion, an aqueous dispersion comprising 60 wt% to 90 wt% water, 10 wt% to 30 wt% PVA, and 0.5 wt% to 3 wt% corn starch, wherein the coating material 40 may additionally comprise 0.2 wt% to 1 wt% defoamer selected from water-insoluble alcohol ethoxylates or water-soluble alcohol ethoxylates.

[0047] Applying the coating material 40 onto the substrate 30 can be achieved by methods known to those skilled in the art (e.g., dip coating, wash coating, spray coating, roll coating, and / or spin coating). Additionally, as... Figure 6 As shown, coating material 40 can be applied to substrate 30, wherein the coating machine 200 includes a substrate (e.g., paper) dispenser 202, the substrate 30 is discharged from the dispenser through a first applicator 204, and the coating material 40 is deposited from the first applicator onto a first surface of substrate 30. The coated substrate 30 (i.e., insert 20) then passes through a series of winding metering rods 206 (e.g., Mayer rods), around a guide rod 208, and through a first drying device 210 to further dry the coating material 40 on the first surface of substrate 30. The insert 20 is then flipped, and the coating material 40 is deposited onto a second surface of substrate 30 through a second applicator 212. The insert 20 then again passes through a series of winding metering rods 206, around a guide rod 208, and through a second drying device 214 to further dry the coating material 40 on the second surface of substrate 30.

[0048] Once the coating material 40 has dried on one or more surfaces of the substrate 30, the coating material 40 may contain, for example, 2 wt% to 15 wt% of wet strength additive, such as 3 wt% to 10 wt% of wet strength additive, and further such as 4 wt% to 8 wt% of wet strength additive, based on the total weight of the coating material 40.

[0049] Additionally, once the coating material 40 has dried on one or more surfaces of the substrate 30, the coating material 40 may contain, for example, 1 wt% to 5 wt% of surfactant and / or defoamer, such as 2 wt% to 4 wt% of surfactant and / or defoamer, based on the total weight of the coating material 40.

[0050] For example, in some exemplary embodiments, once the coating material 40 has dried on one or more surfaces of the substrate 30, the weight ratio of the dispersion medium to the wet strength additive in the coating material 40 can range from 5:1 to 50:1, such as 10:1 to 40:1, and further such as 15:1 to 25:1. Additionally, in some exemplary embodiments, once the coating material 40 has dried on one or more surfaces of the substrate 30, the weight ratio of the dispersion medium, surfactant, and / or defoamer in the coating material 40 can range from 20:1 to 100:1, such as 40:1 to 80:1.

[0051] For example, the embodiments disclosed herein include those in which, based on the total weight of the coating material 40, the coating material 40, once dried on one or more surfaces of the substrate 30, comprises 85 wt% to 98 wt% of a dispersion medium and 2 wt% to 15 wt% of a wet strength additive, wherein the coating material 40 may additionally comprise 1 wt% to 5 wt% of a surfactant and / or a defoamer. Such embodiments include coating materials based on the total weight of the coating material 40 comprising 90 wt% to 98 wt% of PVA and 2 wt% to 15 wt% of corn starch, wherein the coating material 40 may additionally comprise 1 wt% to 5 wt% of a defoamer selected from water-insoluble alcohol ethoxylates or water-soluble alcohol ethoxylates.

[0052] Example

[0053] The embodiments disclosed herein are further illustrated by the following non-limiting examples.

[0054] Example 1:

[0055] Coating and sample preparation:

[0056] To prepare the first coating material, 100 ml of water was first placed in a glass beaker and stirred using a magnetic stir bar and a hot plate. The water was then heated to 60°C. Next, 20 g of PVA 4-88 (Kuraray) was slowly added to the water and dissolved, ensuring no clumping occurred at the water / air interface. Once the PVA was completely dissolved, the solution was heated to 90°C and stirred for 3 hours, then cooled. A second coating material containing a wet strength additive was prepared by adding 1 g of corn starch (Sigma Aldrich catalog number S 4180) and 19 g of PVA 4-88 to 100 ml of water at 60°C, using the same additional preparation steps described above. Once each solution cooled, blade casting was performed on strips of paper used for Mini Dense Packaging and accelerated aging studies, as described below (the pull-down application method is used for the wet tensile testing method described below). Specifically, to prepare the coated paper samples, a blade caster (TQC, AB3405, serial number 034) was used, in which approximately 2.5–3 ml of coating was placed on top of the paper (NVA 45 gsm, Alberta Newsprint Company or Catalyst 54 gsm, Paper Excellence). A pull-down rod (BYK, for depositing a 2 mm wet film thickness on the top of the paper) was then placed over the solution. The coating was then pulled down over the paper at a speed of 125 mm / s on one side. The coated paper was then dried in a hood. When completely dry, the other side was coated. When both sides were coated, the paper samples were then cut to the required size for each test. These tests included mini-dense packing (vibration test), water contact angle, and accelerated aging. For the wet tensile test, only one side of the sample was coated, as described below.

[0057] Example 2:

[0058] Wet tensile test method and results:

[0059] Coated with PVA 4-88 (Kuraray Corporation) (with or without corn starch (and formulated as described in Example 1), and additionally comprising 0.4 wt% Tergitol). ®The tensile testing of 15-S-3 paper essentially follows the TAPPI / ANSI standard T-456, using a coating instead of water. In short, a seven-inch strip of paper (Newsprint NVA 45 or 52 gsm from Alberta Newsprint) is cut in machine orientation, and the thickness is measured at five points. The coating is then applied to one side of the paper using a pull-down machine, and the paper is placed in an Instron tensile testing machine within two minutes of coating application to minimize any coating evaporation. The wet-coated paper is then pulled at 25 mm / min until it breaks at the center. If the breakage occurs near the clamping point, the measurement is ignored. Aluminum foil can be used at the edges of the paper strip to allow for better clamping by the Instron clamp. The breaking energy is then calculated to determine whether the additive improves the paper's wet strength by determining the area under the force-distance curve. Figure 7 The increased breaking energy observed when corn starch additive in the formulation is used at a level of 1 wt% is shown.

[0060] Example 3:

[0061] Miniature dense packaging test methods and results:

[0062] 4-inch by 4-inch Corning steel with a thickness of 0.5 mm ® Eagle XG ®The glass samples were initially cleaned so that fewer than one particle was observed per square centimeter (using a Toray laser particle counter) and the water contact angle was less than 5 degrees (as measured by a Kruss analyzer). Stacks were then prepared, alternating between inserts of interest and glass. Specifically, during the stacking and vibration tests, one side of the paper being tested was stacked on the “A” side of the glass, oriented vertically “up.” Prior to the tests, the stacks were aged overnight at approximately 25°C and controlled at 54% relative humidity. The stacks were then placed in a device designed to simulate commercial glass packaging conditions, referred to herein as mini-dense packaging (MDP), which was fixed to a vibration table unit in which a humidity chamber was assembled around the stack device and controlled at the desired level (50% relative humidity at approximately 25°C) for the duration of the two-hour vibration test. The vibration frequencies experienced during the tests were selected and controlled based on field testing of the transport environments experienced by the manufactured large glass sheets. After vibration, the stacks were removed and placed in a black carrier box. The number of particles on the vibrated surface (referred to herein as "post-MDP") was counted using a Toray laser particle counter. The glass was then subjected to a standard washing procedure, in which the glass was exposed to a detergent bath for 1 minute, a water bath for 1 minute, followed by a rinse-and-dry step. The number of particles on the washed surface (referred to herein as "post-MDP + post-wash") was counted again using a Toray laser particle counter.

[0063] The above procedure was repeated for control samples containing uncoated GCIP D paper (Tokushu, Japan) and samples coated with a coating composition containing PVA and corn starch as described in Example 1. In these experiments, the uncoated control samples (with the felt side facing the "A" side of the glass) were tested on the same day or within the same week as the coated samples to determine the confidence level of the data related to the paper of interest. Figure 8 and 9 The control sample is shown. Figure 8 ) and coated sample ( Figure 9 A comparison was made between the two samples. The results indicated that, after vibration and washing, the particle density of the coated sample was approximately equal to that of the control sample.

[0064] Example 4:

[0065] Accelerated aging test methods and results:

[0066] Prepare uncoated GCIP D paper samples and coated with the corn starch formulation of Example 1, additionally comprising 0.4 wt% Tergitol. ®The sample was 15-S-3 and exposed to Corning in a stack of cellophane. ® Eagle XG ® The glass was then placed in a closed oven (CSZ-A Gentherm Company, model MCH-3-.33-.33-H / AC) set to 85°C and 85% relative humidity for 24 hours. The paper was removed from the stack, and the glass was washed according to the mini-dense packaging test method described above. The water contact angle (Krüz DCA 100) was then measured. Figure 10 The results are shown. Since a water contact angle of 10 degrees or less is considered clean glass, both the uncoated GCIP D and the coated samples showed pass conditions.

[0067] The embodiments disclosed herein (wherein the insert coating material includes a wet strength additive) enable the production of inserts (such as inserts used in conjunction with the packaging and transport of glass articles), wherein the inserts maintain desirable properties (such as tensile strength) while enabling the packaging and transport of glass articles with low surface contamination and high washability for extended periods in, for example, relatively hot and / or humid environments. For example, according to the wet tensile testing method described herein, the embodiments disclosed herein enable the production of inserts (such as paper inserts) that increase the breaking energy of wet paper coated with the coating material by at least 25%, such as at least 30%, and further such as at least 35%, such as 25% to 50%, and further such as 30% to 40%, compared to the breaking energy of wet paper in any coating material without a wet strength additive.

[0068] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of this disclosure without departing from the spirit and scope of this disclosure. Therefore, this disclosure is intended to cover such modifications and variations, provided that such modifications and variations fall within the scope of the appended claims and their equivalents.

Claims

1. An insert comprising: Paper substrate, the paper substrate comprising a first main surface and an opposite second main surface; and A coating material, said coating material being deposited on at least one of the first main surface or the second main surface, said coating material comprising: Dispersion medium; and Wet strength additive.

2. The insert according to claim 1, wherein the wet strength additive comprises starch.

3. The insert according to claim 1, wherein the coating material comprises an antifoaming agent.

4. The insert according to claim 3, wherein the defoamer is water-insoluble.

5. The insert according to claim 4, wherein the defoamer comprises a water-insoluble alcohol ethoxylate.

6. The insert according to claim 3, wherein the defoamer is water-soluble.

7. The insert according to claim 6, wherein the defoamer comprises a water-soluble alcohol ethoxylate.

8. The insert according to claim 1, wherein the paper comprises thermochemically pulped paper.

9. The insert according to claim 1, wherein the paper comprises mechanically pulped paper.

10. The insert according to claim 1, wherein the dispersion medium comprises at least one of the following: polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylamide (PAAm), polyethylene glycol (PEG), hydroxypropyl methylcellulose (HPMC), poly-4-styrene sulfonate, or polydiallyl dimethyl ammonium chloride.

11. The insert according to claim 1, wherein the coating material comprises 2 wt% to 15 wt% of the wet strength additive.

12. A method for packaging a glass plate, the method comprising: Positioning two or more glass plates in a packaging device; and An insert is placed between adjacent glass plates in one or more of the glass plates, the insert comprising: Paper substrate, the paper substrate comprising a first main surface and an opposite second main surface; and A coating material, said coating material being deposited on at least one of the first main surface or the second main surface, said coating material comprising: Dispersion medium; and Wet strength additive.

13. The method of claim 12, wherein the wet strength additive comprises starch.

14. The method of claim 12, wherein the coating material comprises an antifoaming agent.

15. The method of claim 14, wherein the defoamer is water-insoluble.

16. The method of claim 15, wherein the defoamer comprises a water-insoluble alcohol ethoxylate.

17. The method of claim 14, wherein the defoamer is water-soluble.

18. The method of claim 17, wherein the defoamer comprises a water-soluble alcohol ethoxylate.

19. The method of claim 12, wherein the paper comprises thermochemically pulped paper.

20. The method of claim 12, wherein the paper comprises mechanically pulped paper.

21. The method of claim 12, wherein the dispersion medium comprises at least one of the following: polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylamide (PAAm), polyethylene glycol (PEG), hydroxypropyl methylcellulose (HPMC), poly-4-styrene sulfonate, or polydiallyl dimethyl ammonium chloride.

22. The method of claim 12, wherein the coating material comprises 2 wt% to 15 wt% of the wet strength additive.

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