WO2024102297A1

WO2024102297A1 - Glass substrate interleaf material and coating therefor

Info

Publication number: WO2024102297A1
Application number: PCT/US2023/036681
Authority: WO
Inventors: Gilbert Alexander CASTILLO; Nityanshu Kumar; Christine Marie MAHONEY FAHEY; Elizabeth Irene Luther MORIN; Siva Venkatachalam; Wanda Janina Walczak
Original assignee: Corning Incorporated
Priority date: 2022-11-09
Filing date: 2023-11-02
Publication date: 2024-05-16
Also published as: CN118007471A

Abstract

An interleaf material including a paper substrate. A polymer coating material for coating the paper substrate is also disclosed. The paper substrate may comprise a polymer coating material configured as a coating for paper substrates. An interleaf material comprising a paper substrate, and a stack of glass substrates separated by the interleaf material are also disclosed.

Description

GLASS SUBSTRATE INTERLEAF MATERIAL AND COATING THEREFOR

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 63/423938 filed on November 9, 2022, the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD

[0002] The present disclosure relates to interleaf materials for separating glass substrates, and in particular to interleaf materials comprising a paper substrate. A coating for coating paper substrates and a stack of glass substrates separated by an interleaf material formed therefrom are also disclosed.

BACKGROUND

[0003] In the packing and transportation of glass substrates, such as glass substrates used for display applications, an interleaf material, such as an interleaf paper, is commonly interposed between glass substrates to help protect the glass substrates from damage. In addition to providing physical protection, an interleaf material may also be designed to minimize the transfer of contaminants onto the glass surface.

SUMMARY

[0004] In a first aspect, a polymer coating material for paper substrates is disclosed, comprising polyvinyl alcohol, and, for every one-part by weight polyvinyl alcohol, about 0.016 parts by weight to about 0.03 parts by weight of a defoaming agent and about 0.05 parts by weight to about 0.625 parts by weight of a lubricant.

[0005] In a second aspect, the coating material of the first aspect may further comprise, for every one-part by weight polyvinyl alcohol, 0.067 parts by weight of an antistatic agent.

[0006] In a third aspect, the coating material of the first aspect or the second aspect may further comprise, for every one-part by weight polyvinyl alcohol, about 0.059 parts by weight to about 0.077 parts by weight of a hydrogen bond breaker.

[0007] In a fourth aspect, an interleaf material for separating glass substrates is described, comprising a paper substrate comprising at least one of lignin or cellulose, a first major surface, and a second major surface opposite the first major surface. The interleaf material further comprises a polymer coating disposed on at least one of the first major surface or the second

1

RECTIFIED SHEET (RULE 91) ISA/KR major surface of the paper substrate, the polymer coating comprising polyvinyl alcohol, and, for every one-part by weight polyvinyl alcohol, about 0.016 parts by weight to about 0.03 parts by weight of a defoaming agent and about 0.05 parts by weight to about 0.625 parts by weight of a lubricant.

[0008] In a fifth aspect, the coating of the fourth aspect may comprise about 0.067 parts by weight of an antistatic agent for every one-part by weight polyvinyl alcohol.

[0009] In a sixth aspect, the antistatic agent of the fifth aspect may comprise, poly 4 styrene sulfonate or an amine ethoxylate.

[0010] In a seventh aspect, the coating of any one of the fourth to the sixth aspects may comprise about 0.059 parts by weight to about 0.077 parts by weight of a hydrogen bond breaker for every one-part by weight polyvinyl alcohol.

[0011] In an eighth aspect, a thickness of the coating on the at least one of the first major surface or the second major surface of any one of the fourth through the seventh aspects may be in a range from about 2 micrometers to about 10 micrometers.

[0012] In a ninth aspect, the coating of any one of the fourth through the seventh aspects may be a continuous coat on the at least one of the first major surface or the second major surface. [0013] In a tenth aspect, both the first major surface and the second major surface of the ninth aspect are coated with the coating.

[0014] In an eleventh aspect, the interleaf material of any one of the fourth through the tenth aspects may be in roll form.

[0015] In a twelfth aspect, a thickness of the interleaf material of any one of the fourth through the eleventh aspects may be equal to or less than about 200 micrometers.

[0016] In a thirteenth aspect, an MD tensile strength of the paper substrate of any one of the fourth aspect through the twelfth aspects may be equal to or greater than about 2.86 kilograms/centimeter of width of the paper substrate when measured according to TAPPI T- 494.

[0017] In a fourteenth aspect, a CD tensile strength of the paper substrate of any one of the fourth aspect through the thirteenth aspects may be equal to or greater than about 0.7 kg/cm of width of the paper substrate when measured according to TAPPI T-494.

[0018] In a fifteenth aspect, a tear strength of the paper substrate of any one of the fourth aspects through the fourteenth aspects may be equal to or greater than 18 grams for 8 plies when measured according to TAPPI T-414. [0019] In a sixteenth aspect, a basis weight of the paper substrate of any one of the fourth aspect through the fifteenth aspects, expressed as mass in grams per square meter, may be in a range from about 40 g/m² to about 120 g/m².

[0020] In a seventeenth aspect, a stack of glass substrates is disclosed, comprising a plurality of glass substrates arranged in a stack, adjacent glass substrates of the plurality of glass substrates separated by the interleaf material of any one of the fourth through the sixteenth aspects.

[0021] Both the foregoing general description and the following detailed description present embodiments intended to provide an overview or framework for understanding the nature and character of the embodiments disclosed herein. The accompanying drawings are included to provide further understanding and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a cross-sectional edge view of an exemplary interleaf material;

[0023] FIG. 2 is a bar graph showing normalized intensity resulting from TOF SIMS measurements of paper substrate samples after being subjected to a coronal discharge at varying powers, with and without aging;

[0024] FIG. 3 is a bar graph showing normalized intensity resulting from TOF SIMS measurements of PDMS -contaminated paper substrate samples (sum of PDMS ions) after being subjected to coronal discharge, exposure to laser radiation, and ozone produced from ultraviolet light exposure;

[0025] FIG. 4 is a bar graph showing normalized intensity resulting from TOF SIMS measurements of PDMS -contaminated paper substrate samples (sum of PDMS ions) of FIG. 4 after being subjected to coronal discharge, exposure to laser radiation, and ozone produced from ultraviolet light, and showing levels of silica in the samples;

[0026] FIG. 5 is a bar graph showing normalized intensity resulting from TOF SIMS measurements of PDMS -contaminated paper substrate samples (sum of PDMS ions) as a function of molecular weight of a PVA-based coating material;

[0027] FIG. 6 is a plot showing FTIR spectral response a function of wavenumber for two PDMS suppressant materials and PDMS);

[0028] FIG. 7 is a plot showing FTIR spectral response a function of wavenumber for two PDMS suppressant materials and PDMS); [0029] FIG. 8 is a bar graph showing normalized intensity resulting from TOF SIMS measurements of PDMS -contaminated paper substrate samples for a control siloxane (CS9K) and PDMS suppressant polymer-treated Eagle XG glass slides with and without washing (rinsing);

[0030] FIG. 9 is a plot showing surface tension as a function of a PDMS suppressant concentration in weight percent when added to a PVA coating material;

[0031] FIG. 10 is a bar graph showing the defoaming ability of PDMS-suppressant polymers as exhibited by volume increase of a PVA coating solution containing a PDMS suppressant;

[0032] FIG. 11 is a plot showing that even at a 1 wt% addition of suppressant polymer to a PVA-based coating, the addition of the PDMS suppressant does not influence the viscosity of the PVA-based coating;

[0033] FIG. 12 - FIG. 15 are line scans of water contact angle on 4 inches Si -wafers contaminated with PDMS and showing negligible change in water contact angles after aging for PDMS-suppressant containing PVA based coatings;

[0034] FIGS. 16-17 are bar graphs showing the number of particles per square centimeter before and after vibration testing, and after subsequent washing, of a stack of glass substrates interleaved with a plain paper interleaf material (FIG. 16), and with a PDMS-suppressant PVA- based coated paper substrate (FIG. 17),

[0035] FIG. 18 is a cross-sectional side view of a stack of glass substrates comprising interleaving material disposed between adjacent glass substrates;

[0036] FIG. 19 is a plot of water contact angle measured on a variety of interleaf materials;

[0037] FIG. 20 is a plot of normalized PDMS concentration on glass surfaces after contact with a variety of interleaf materials;

[0038] FIG. 21 is a plot of particle density for several interleaf materials after vibration testing and subsequent washing; and

[0039] FIGS. 22-24 are plots of particle density for several interleaf materials after a Vibration and Wash test: before testing, after vibration, and after wash.

DETAILED DESCRIPTION

[0040] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. However, this disclosure can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. [0041] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art.

[0042] Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value to the other particular value. Similarly, when values are expressed as approximations by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0043] Directional terms as used herein — for example, up, down, right, left, front, back, top, bottom — are made with reference to the figures as drawn and are not intended to imply absolute orientation.

[0044] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus, specific orientations be required. Accordingly, where a method claim does not recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0045] As used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0046] The word “exemplary,” “example,” or various forms thereof are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” or as an “example” should not be construed as preferred or advantageous over other aspects or designs. Furthermore, examples are provided solely for purposes of clarity and understanding and are not meant to limit or restrict the disclosed subject matter or relevant portions of this disclosure in any manner. It can be appreciated that a myriad of additional or alternate examples of varying scope could have been presented but have been omitted for purposes of brevity.

[0047] As used herein, the terms “comprising” and “including,” and variations thereof, shall be construed as synonymous and open-ended, unless otherwise indicated. A list of elements following the transitional phrases comprising or including is a non-exclusive list, such that elements in addition to those specifically recited in the list may also be present.

[0048] The terms “substantial,” “substantially,” and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, “substantially” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0049] As used herein, the term “interleaf material,” or variations thereof, refers to a material interposed between glass substrates to provide a protective cushion between adjacent glass substrates and protect surfaces of the glass substrates from damage and/or contamination. An interleaf material may comprise a substrate material, for example a paper material, or a polymer material, or a combination thereof.

[0050] The transfer of contaminants, such as particles and/or chemical species originating from the interleaf material, while reduceable, is difficult to altogether prevent. Nevertheless, interleaf material should be capable of reducing the adherence of particles transferred to the glass substrates, such as particles originating from the interleaf material, making these particles easy to wash from the glass substrate surfaces. Work to reduce contamination on stacked (e.g., packaged) glass substrates has involved the addition of talc, group II elements, aluminum, or the like, to paper substrates to produce an interleaf material for interposing between glass substrates.

[0051] As used herein, the term paper, or paper substrate, refers to an organic fiber-based material comprising cellulose and/or lignin. Such paper substrates are generally sourced from wood fiber (e.g., pulp) and processed to contain varying amounts of cellulose and/or lignin. Referring to FIG. 1 showing an interleaf material comprising a paper substrate 12, the paper substrate 12 can have a thickness T defined between a first major surface 14 and a second major surface 16 less than about 180 micrometers, such as less than about 170 micrometers, for example less than about 160 micrometers. Suitable papers may include newsprint, high cellulose papers, high lignin papers, and intermediate lignocellulose papers. The paper substrate may have a machine direction (MD) tensile strength equal to or greater than about 16 Ib/inch (2.86 kilograms/centimeter) width and a cross machine direction (CD) tensile strength equal to or greater than about 3.90 pounds/inch (0.7 kg/cm) width when measured according to TAPPI T-494 (Technical Association of the Pulp & Paper Industry Inc.). The paper substrate may have a tear strength equal to or greater than 18 grams for 8 plies of paper substrate when measured according to TAPPI T-414. The paper substrate may have a basis weight in a range from about 40 g/m² to about 120 g/m², for example in a range from about 40 g/m²to about g/m² 110, in a range from about 40 g/m² to about 100 g/m², in a range from about 40 g/m² to about 90 g/m², in a range from about 40 g/m² to about 80 g/m², in a range from about 40 g/m² to about 70 g/m², in a range from about 40 g/m² to about 60 g/m², or in a range from about 40 g/m² to about 50 g/m².

[0052] In some embodiments, the paper substrate may have one or both major surfaces 14, 16 treated. For example, at least one of the first major surface 14 or the second major surface 16 may be exposed to a coronal discharge during which time contaminants such as polydimethyl siloxane (PDMS) contained on and/or within the paper substrate may be converted to a benign form, e.g., silica. PDMS is a generally ubiquitous contaminant often found on processed paper arising from the paper manufacturing process. PDMS residue transferred to a glass substrate surface from the paper substrate, when used, for example, as an interleaving material, may interfere with subsequent processing of the glass substrate. For example, the presence of PDMS residue may interfere with the deposition of nano or macro electronic structures on surfaces of the glass substrate that may be deposited on the glass substrate in the manufacture of an electronic display device. As little as 2.5 ppm of 9000 grams/mole molecular weight PDMS can result in black matrix film delamination in a color filter manufacturing process where a black matrix material is applied to a glass substrate. In some instances, PDMS contamination of commercially available paper can be as high as what would be obtained by purposely contaminating the paper substrate at levels of 250 ppm to 2500 ppm PDMS. Accordingly, in some embodiments, a paper substrate can be surface treated by exposing the paper substrate to a coronal discharge, which can convert the PDMS to silica.

[0053] In an experiment, GCIP D paper (Tokushu Tokai Paper Co., Japan) known not to contain PDMS or silicone contaminants was intentionally contaminated with 20 microliters (pl) of 250 ppm 9000 grams/mole molecular weight PDMS, equivalent to 0.81 pg/cm². The PDMS solution was made by dissolving a known amount of PDMS in a known amount of chloroform. After doping the GCIP D paper with the PDMS solution, the chloroform was allowed to evaporate. The paper was then surface treated using a variety of techniques (UVO, coronal discharge, 196 nm laser). For example, in the case of coronal discharge, the PDMS- doped paper was exposed to either 400 watts power at 10 feet (3.048 meters) per minute (equivalent to 21.8 watt minutes/foot² watt density) for a single or quadruple pass, or at 500 watts at 5 feet (1.524 meters) per minute (equivalent to 54.5 watt minutes/foot² watt density) for a single or quadruple pass. Watt density is calculated as power in watts/(electrode width x speed of conveyance past the electrode) . The PDMS signature of the pdms-doped area was then compared among the various paper substrates either directly after treatment (time = 0) or after aging for 2 weeks at 54% RH. The paper substrates were measured forthe presence of PDMS using Time of Flight Secondary Ion Mass Spectrometry (TOF SIMS). TOF SIMS employs a pulsed primary ion beam and a time-of-flight mass analyzer to detect molecular ions with mass- to-charge ratios in a range from about m/z = 1 to about m/z = 10,000. To generate the PDMS signal by TOF SIMS, the sum of PDMS specific peaks at at mass-to-charge ratios m/z of 74, 148, 207, 221 and 281 were used.

[0054] FIG. 2 is a plot illustrating a comparison of TOF SIMS responses for various conditions (e.g., power, number of passes, or after aging for two weeks) after the GCIP D paper was exposed to coronal discharge from a 3DT Polydyne™ Pro Module Conveyor with Corona Treating System (Part Number 10036-36) having an electrode width of 1.8 feet. As described above, the positive control paper was GCIP D contaminated with 250 ppm of 20 pl of 9000 molecular weight PDMS. The negative control paper was uncontaminated GCIP D paper. Further data includes the positive control paper exposed to a coronal discharge at 400 watts and passed through the coronal discharge apparatus one time at 10 feet (3.048 meters) per minute; the positive control paper exposed to a coronal discharge at 400 watts and passed through the coronal discharge apparatus one time at 10 feet (3.048 meters) per minute and aged for 2 weeks at 54% relative humidity (RH); the positive control paper exposed to a coronal discharge at 400 watts and passed through the coronal discharge apparatus four times at 10 feet (3.048 meters) per minute; the positive control paper exposed to a coronal discharge at 400 watts, passed through the coronal discharge apparatus four times at 10 feet (3.048 meters) per minute, and aged for 2 weeks at 54% RH; the positive control paper exposed to a coronal discharge at 500 watts and passed through the coronal discharge apparatus one time at 5 feet (1.524 meters) per minute; the positive control paper exposed to a coronal discharge at 500 watts, passed through the coronal discharge apparatus one time at 5 feet (1.524 meters) per minute, and aged for 2 weeks at 54% RH; the positive control paper exposed to a coronal discharge at 500 watts and passed through the coronal discharge apparatus four times at 5 feet (1.524 meters) per minute, and; the positive control paper exposed to a coronal discharge at 500 watts, passed through the coronal discharge apparatus four times at 5 feet (1.524 meters) per minute, and aged for 2 weeks at 54% RH. The data show the PDMS signature was greatly reduced after coronal treatment compared to the positive control and stayed reduced even after 2 weeks of aging.

[0055] In further experiments, GCIP D paper was treated by exposing the paper to ultraviolet light. A UVOCS TIOxlO ultraviolet ozone (UVO) system was used. The system employs a low pressure quartz mercury vapor lamp to generate UV light in wavelengths of about 185 nanometer (nm) and 254 nm and produce ozone and atomic oxygen. Organic contaminant molecules are excited or dissociated by absorption of the 254 nm wavelength UV light. The excited organic contaminants react with the atomic oxygen to form volatile products such as CO2 and H2O. The process takes place at room temperature.

[0056] In still other experiments, GCIP D paper was exposed to pulsed light from a laser (GigaPhoton model GT64A) at a wavelength of 193 nm operating at a pulse rate of 50 Hz, which directed a beam of 0.5 watts across a 1-inch diameter area of the paper surface at 15 milliJoules (mJ) per pulse. Exposure time was 1 minute.

[0057] FIG. 3 is a plot comparing test results for laser exposure, coronal discharge exposure, and UV ozone exposure. The positive control was GCIP D paper contaminated with 20 pl of 9000 molecular weight PDMS and the negative control was uncontaminated GCIP D paper. Data for the 196 nm laser represents a positive control sample exposed to light from the 196 nm laser for 1 minute; data for coronal discharge represents a positive control sample exposed to 400 watt coronal discharge at 10 feet (3.048 meters) per minute for 1 pass, and; data for UV ozone exposure represents positive control samples exposed to UV generated ozone for 5 minutes and 10 minutes.

[0058] Further data, provided in FIG. 4, show normalized silica TOF SIMS signal intensity after testing with coronal discharge, 196 nm wavelength laser, and UV ozone exposure for comparison with the data of FIG. 3. TOF SIMS showed that as the PDMS signal was reduced, the SiO2 signal was increased, suggesting PDMS was converted to silica. Rubbing the contaminated paper after surface treatment against Coming® Eagle XG® glass did not show visible scratching as determined by confocal microscopy. [0059] In aspects, interleaf materials described herein may comprise a polymer coating material. Surfaces of the paper substrate may be pretreated (such as by any one or more of the foregoing coronal discharge, laser or UV ozone treatments) prior to application of the coating material. In embodiments, the coating material may be water soluble. The coating material may be applied on at least one major surface of the paper substrate, although typically the polymer coating material is applied to both major surfaces of the paper substrate. Suitable coating materials may comprise polyvinyl alcohol (PVA), although in further aspects, the coating material may comprise polyacrylic, polyvinyl pyrrolidone, hydroxyethyl cellulose polymer, and/or polyethylene glycol. The polymer material may comprise one or more additives. For example, in addition to polymer base (e.g., PVA), the polymer coating material may comprise one or more of a defoaming agent, a lubricating agent, a hydrogen bond breaker, an antistatic agent, and/or a thickener. The total amount of additives may be such that for every one-part by weight PVA, there are about 0.046 parts by weight to about 0.13 parts by weight total additives. The polymer coating material may further comprise water.

[0060] The polymer coating material may have a weight averaged molecular weight in a range from about 8680 grams/mole to about 40,000 grams/mole, for example in a range from about 8680 grams/mole to about 16654 grams/mole, with a polydispersivity in a range from about 7.23 to about 22.38, respectively, corresponding to a PVA coating material hydrolyzed at about 40% to about 98%, for example in a range from about 45% to about 98%, for example in a range from about 50% to 98%, for example in a range from about 55% to 98%, in a range from about 60% to about 98%, in a range from about 65% to about 98%, in a range from about 70% to about 98%, in a range from about 75% to about 98%, in a range from about 80% to about

98%, in a range from about 85% to about 98%, or in a range from about 88% to about 98%.

Polymer solubility was measured via the Hansen solubility parameter, 8,

AS = [(8d,p - 8_d,s)² + [(8_PP - 8_p,s)² + (5h.p - 8_h,s)²] ^1/2 (1)

Ra² = 4(8DI - 8D2)² + (8pi - Sp2)² + (8HI - 8H2)² (2) where Ra is the distance between Hansen parameters in Hansen space. The method is described, for example, in Properties of Polymers by D.W. Van Krevelen, 1990, Elsevier, p. 219, equation 7.13. The three parameters 6d, 8_P, and 8h form a three-dimensional space (the Hansen space). The parameter 8d represents the energy from dispersive forces between molecules, the parameter 8_P represents the energy from dipolar intermolecular forces between molecules, and the parameter 8h represents the energy from hydrogen bonds between molecules. The subscripts P and S designate polymer and solvent, respectively. Lower AS values indicate better solubility and less issues with glass sticking. Similarly, the closer two molecules are within the Hansen space (smaller Ra), the more likely one molecule will dissolve in the other. Polymers other than PVA expected to be beneficial in the manufacture and use of the polymer material as a paper substrate coating for glass interleaf materials may have polymer/cellulose solubilities expressed as a ratio of 5.1 or less, while polymers not expected to be beneficial may have polymer/cellulose solubilities of 18.8 and above. Polymers having polymer/cellulose solubilities greater than about 5.1 but less than about 18.8 may be problematic (e.g., may or may not perform beneficially, depending on the polymer used).

[0061] Higher molecular weight is shown to prevent migration of PDMS more compared to lower molecular weight PVA. To test the effect of molecular weight of PVA (poly vinyl alcohol) on the ability of PDMS to migrate through a coating, silicon wafers were contaminated with known amounts of PDMS, dried, and covered with different molecular weight PVA film by spin coating. Film thickness of the PVA was nominally 2 micrometers for 4-88 and 4 micrometers for 4-98 and 22-88. The samples were then aged for 4 weeks and analyzed via TOF SIMS on the PVA surface for presence of PDMS. The grades of PVA (Kuraray Corporation) used were 4-88, 4-98 and 22-88. The first number in each series refers to the molecular weight while the second number after the hyphen refers to PVA hydrolysis level. Thus, PVA 4-88 has a weight averaged molecular weight of about 13000 grams/mole while PVA 22-88 has a weight averaged molecular weight of about 37000 grams/mole. Accordingly, 22-88 is a higher molecular weight than either 4-88 or 4-98. It was shown (see FIG. 5) that after 4 weeks aging 22-88 does not exhibit any PDMS for levels that were on the silicon wafer of up to 250 ppm, in contrast to the 4-88 and 4-98 samples.

[0062] The polymer coating material may include one or more defoaming agents to minimize foaming of the polymer coating material during pumping or mixing of the polymer. For example, during the pumping of highly hydrolyzed (e.g., equal to or greater than about 85% hydrolyzed PVA), stable bubbles with water can be formed. A defoaming agent is a chemical additive that reduces, for example hinders, the formation of foam, for example in industrial process liquids, and in particular, PVA-based polymer coating materials described herein. Generally, exemplary defoaming agents may be insoluble oils, various silicones, alcohols, sterates, and glycols. However, suitable defoaming agents for use in polymer coating materials described herein should be silicone-free to prevent potential silicone contamination of the glass surface. Foamability of the PVA-based polymer coating material can be tested by determining the amount of foam height that occurs after mixing or pumping. It can also be assessed by volume or weight. The defoaming agent concentration may be such that for every one-part by weight polyvinyl alcohol, the polymer coating material may comprise 0.016 parts by weight to about 0.03 parts by weight defoaming agent. Suitable defoaming agents may include, for example, Tergitol 15-S-3 (a secondary alcohol ethoxylate nonionic surfactant, available from Dow Chemical), although other suitable defoaming agents can include Surfynol® 420 (a self- emulsifiable nonionic dynamic wetting agent and defoamer based on acetylenic diol, available from Evonik), Dee Fo® 215 (a blend of waxes and mineral oil, available from Mtinzing Chemie), and GEO FM® VF (a 100% active nonionic, water dispersible liquid coating defoamer, available from GEO Specialty Chemicals). Defoaming efficacy by mixing was evaluated by including a starting volume of 200 ml of polymer coating material and adding the desired amount of defoaming agent, then mixing for 10 minutes. At the completion of mixing, the change in volume was determined. The change in mass for a 5 milliliter (ml) volume sample was also determined. To determine efficacy by pumping, a pneumatic diaphragm pump capable of a maximum flow rate of 7 gallons/minute (26.5 liters/minute) was utilized. The air pressure was set to 50 psi (0.34 megapascal) to yield a flow rate of 1. 1 to 1.5 liters/minute. A 20,000-milliliter plastic graduated cylinder was positioned in a secondary container and dropped from a height of 37 inches (94 centimeters) from the floor. Starting at 1000 milliliter, the pump was run for 10 minutes. Foaming was visually assessed.

[0063] The polymer coating material may further include a lubricating agent (lubricant) to reduce peel force (e.g., coefficient of friction) and promote handling ease. The lubricant may comprise, for example, a wax-based (e.g., natural or synthetic) lubricant such as ethylene bis stearamide (EBS). The lubricant may be present in an amount such that for every one-part by weight polyvinyl alcohol in the polymer coating material, the polymer coating material may comprise about 0.05 parts by weight to about 0.625 parts by weight lubricant. The efficacy of the lubricant was measured according to ASTM DI 894, Static and Kinetic Coefficient of Friction of Plastic Films and Sheeting.

[0064] In aspects, the polymer coating material may comprise one or more hydrogen bond breakers suited to increase the hydrophobic characteristic of the polymer coating material. Hydrogen bonds are a primarily electrostatic force of attraction between a hydrogen atom, which is covalently bound to a more electronegative "donor" atom or group, and another electronegative atom bearing a lone pair of electrons. A hydrogen bond breaker is capable of chemically breaking these bonds. Such hydrogen bond breakers may include alkyl ketene dimer (AKD) or alkynyl succinic anhydride (ASA). The hydrogen bond breaker may be added to the polymer coating material in an amount such that for every one-part by weight polyvinyl alcohol, the polymer coating material may comprise about 0.059 parts by weight to about 0.077 parts by weight hydrogen bond breaker. The efficacy of the hydrogen bond breaking agent was assessed by measuring the contact angle of water on a surface of the coated paper as a function of time. The method is described in Improving the Barrier Properties of Packaging Paper by Polyvinyl Alcohol Based Polymer Coating - Effect of the Base Paper and Nanoclay. Polymers, 2021, 13, 1334, p.5, Figure 1(a), the content of which is incorporated herein by reference. The base paper with base PVA coating, with or without hydrogen bond breaker, was assessed for water penetration by determining, via video, when a 2-microliter water droplet disappears into the coated paper as described in the above reference.

[0065] To reduce electrostatic adhesion of the paper substrate to the glass surface, as well as reduce electrostatic attraction of particles to the glass surface, an antistatic agent may be added to the polymer coating material, e.g., to reduce or eliminate the buildup of electrostatic charge. Static charge may be generated, for example, by the triboelectric effect. The antistatic agent may include, for example, poly 4 styrene sulfonate or an amine ethoxylate, such as coco amine ethoxylate (e.g., Ethomeen C25A, available from Nouryon, Amsterdam, The Netherlands), tallow amine ethoxylate, oleyl amine ethoxylate, or the like. The antistatic agent may be added in an amount such that for every one-part by weight polyvinyl alcohol, the polymer coating material may comprise 0.067 parts by weight antistatic agent.

[0066] In embodiments, the polymer coating material may comprise a thickening agent (e.g., alginate) to adjust the viscosity of the polymer coating material and enable high volume manufacturing. A thickening agent can increase the viscosity of a liquid without substantially changing other properties of the liquid. For example, the concentration of thickener may be such that for every one part by weight polyvinyl alcohol, the polymer coating material may comprise about 0.03 parts by weight to about 0.12 parts by weight thickener. Suitable thickeners include alginate, an anionic polysaccharide made from guluronic acid and mannuric acid.

[0067] In some embodiments, the polymer coating may comprise a PDMS suppressant that impedes migration of PDMS. The molecular diffusion of PDMS in a PVA coating occurs due to a chemical potential gradient or concentration gradient of PDMS across the coating, where the driving force can be determined by

<5G = A(ypdms - (/surface), (3) where fG represents a the change in Gibbs free energy, A represents surface area, ypchns represents the surface energy of PDMS and /surface represents the surface energy of the coated surface.

[0068] The PDMS suppressant nullifies the concentration gradient of PDMS, hence, impeding PDMS diffusion. The PDMS suppressant may be water soluble and thus easily washed from the glass surface. The PDMS suppressant addition may be formulated to not affect coating viscosity. Moreover, the PDMS suppressant can reduce the surface tension of the coating and thereby enhance wettability of the coating. Additionally, the PDMS suppressant can have a defoaming ability and may be used in combination with other defoamers. A PDMS suppressant-based coating on a paper substrate may show a significant reduction in particle count after washing of glass substrates interleaved with the coated paper compared to what is obtainable with paper alone as the interleaf material. Classes of compounds that satisfy these conditions are water soluble polymers containing fractions of PDMS, such as PEG- dimethicone, PEG/PPG-dimethicone and dimethylsiloxane-ethylene oxide copolymer. The amount of suppressant added to the polymer (e.g., PVA) coating can vary from about 0.001 wt.% to about 2 wt.%. The water-based coating can be a single component or comprise a mixture of hydrolyzed polyvinyl acetate (polyvinyl alcohol) compounds. Other favorable polymers may comprise polyacrylic, polyvinyl pyrrolidone, hydroxyethyl cellulose polymer, polyethylene glycol. However, the coating is not limited to these polymers and can be expanded to other classes of polymeric and non-polymeric materials. The PDMS suppressant can contain PDMS fragments as a sidechain or in the backbone molecular structure.

[0069] FIG. 6 depicts Fourier-transform infrared spectroscopy (FTIR) data in transmission for Coming Eagle XG glass slides with a PDMS suppressant deposited on the slides at a 250 ppm level using a chloroform solution. WSS1 represents dimethylsiloxane (60% - 70% Ethylene Oxide) block copolymer, WSS2 represents dimethylsiloxane (80-85% Ethylene Oxide) block copolymer, and CS9K represents 9000 molecular weight silicone oil. C-H bands for both the silicone oil (9K) and suppressant polymers can be seen. FIG. 7 depicts FTIR data for EXG glass slides with suppressant polymers after rinsing the slides with deionized (DI) water for 30 seconds. C-H bands for the case of glass slides treated with control silicone are observed. The C-H bands are absent from the slides treated with suppressant polymers. This clearly demonstrates that PDMS suppressant polymers can be easily washed from glass substrates (e.g., the Eagle XG glass), whereas the silicone oil cannot be removed with a DI water rinse. [0070] FIG. 8 shows TOF SIMS normalized intensity for the control siloxane (CS9K) and PDMS suppressant polymer-treated Eagle XG glass slides with and without washing (rinsing). The data show the PDMS suppressant polymer is washable and no PMDS -indicative peaks are remaining after a 30 second DI water rinse. The 2-inch x 2-inch glass slides were dipped for 1 minute in a chloroform solution containing different levels of PDMS suppressant polymer. The glass slides were taken out, dried in air and then nitrogen gas blow dried. The glass slides were then washed for 30 seconds in DI water and then blow dried with nitrogen gas.

[0071] FIG. 9 shows the addition of a PDMS suppressant can decrease the surface tension of 25 wt% aqueous PVA (4-88, Kuraray) coatings. Decreasing surface tension enhances spreadability of the coating (see equation 3). This may further facilitate thin conformal coatings on interleaf paper for protecting glass surfaces. Further, a thin coating may ensure a reduction in coating material cost. FIG. 10 shows the defoaming ability of suppressant polymers as exhibited by volume increase of a PVA coating solution containing a PDMS suppressant, as the suppressant polymer itself may function as a defoamer for PVA coatings. For the data of FIG. 10, the coating solution was stirred in a container for 20 minutes at 500 revolutions per minute (rpm). The control sample is pure 25 wt.% PVA coating solution without PMDS suppressant. Additionally, other defoamers (e.g., Surfynol MD20) and surfactants (e.g., Surfynol 465) are added to the system of PVA+PDMS suppressant the combination shows synergy in defoaming ability. FIG. 11 illustrates that even at a 1 wt% addition of suppressant polymer to a PVA coating, the addition does not influence the viscosity of the PVA-based coating. However, a much lower amount of PDMS suppressant polymer may be sufficient to impede PDMS migration in the coatings as demonstrated in example 3.

S = ysoln./air((Cosdobs/r) — 1) (4) where S represents a spreading parameter of the coating on the substrate paper (e.g., interleaf paper), ysoln./air is the surface tension of the coating solution (e.g., PVA solution), r is the ratio of real contact area to apparent contact area, also known as the roughness ratio, measured by a surface topography measurement tool, e.g., scanning confocal microscope (e.g., Keyence VK-X200) or atomic force microscope, and cosOobs is the measured (using a goniometer) contact angle of the coating solution on interleaf papers. In equation 4, for S < 0, the coating partially wets the surface, wherein the lower the magnitude of the negative quantity, the better the coating spreads. For S > 0, the coating completely wets the surface.

[0072] To test the effect on PDMS barrier properties of a PDMS suppressant addition to the PVA coating, 4 x 4-inch silicon wafers were contaminated with 250 ppm of PDMS, dried, and covered with 25 wt% polyvinyl alcohol coatings (4-88, 88% hydrolyzed PVA, Kuraray) by spin coating. The 25 wt% PVA coating was used as a control. PDMS suppressants were added in an amount of 0. 1 wt.% and 0.5 wt% of to 25 wt% PVA coating to evaluate the effects. The samples were then aged for 6 weeks and 13 weeks. The samples were then analyzed using water contact angle measurements for the presence of PDMS. The data are presented in FIGS. 13-16. For the control coating, PDMS migrated to the coating surface after both 6 weeks and 13 weeks aging. However, for the PVA coating with PDMS suppressant, there was no observable increase in water contact angle, demonstrating superior PDMS barrier properties for the PDMS suppressant-containing coating. PVA 4-88 has a weight averaged molecular weight of about 13000.

[0073] To test the impact of transportation on particle transfer to display glass surfaces from packaging interleaf paper, vibration testing was performed. Coming Eagle XG glass coupons sized 4 x 4 inch were initially cleaned to have less than 1 particle/cm². The particles on the glass coupons were counted in a cleanroom using a Toray laser particle counter. Two stacks were prepared by alternating between 1) the GCIP D paper (control) and the Coming Eagle XG glass coupons, and 2) coated interleaf paper and the Coming Eagle XG glass coupons. The stacks were aged at a controlled relative humidity of 54% overnight prior to the experiment. One stack of 20 Coming Eagle XG glass coupons interleaved with GCIP D paper were placed inside a simulated shipping apparatus affixed to a vibration table unit such that a plane of the stack of glass coupons was arranged at a 72 degree angle and vibrated using an Unholtz-Dickie Corporation vibration system according to Telecordia GR-63 criteria for 2 hours. The stack was then removed from the simulated shipping apparatus and the number of particles on the surface after vibration, referred to as “After vibration”, were counted using the Toray particle counter. The glass coupons were then washed in a detergent bath for 1 minute, a water bath for 1 minute, followed by a rinse-spin dry step. The glass coupons were then counted for particles a third time using the Toray particle counter, and these values are referred to as “After vibration+Wash”. Control of GCIP D was mn to determine the confidence of the data relating to the coated paper. FIGS. 16-17 show particle density data for each step of the vibration experiment process. For FIG. 17, a Catalyst Papers paper was coated with PVA 4-88 at 25 wt% + WSS2 (0.5 wt%) + defoamer (Surfynol MD20, 0.25 wt.%) + surfactant (Surfynol 465, 0.25 wt.%). The paper was coated using a bar coating technique at 200 millimeters/second. The data show a 77% reduction in particle count for the PVA-coated paper over GCIP D after washing. [0074] Polymer coating materials described herein may be applied to a paper substrate by any suitable means, including without limitation rolling onto the paper substrate, spraying, dipping, doctor blade, etc. The polymer coating material may then be cured to produce an interleaf material, for example by air drying. In embodiments, the polymer coating material is applied uniformly to the paper substrate surface. That is, the polymer coating material should be continuous on the paper substrate surface, without gaps (i.e., without uncoated areas on the paper substrate major surfaces). In embodiments, the polymer coating material may be applied to each major surface to a thickness in a range from about 2 micrometers to about 10 micrometers, for example in a range from about 3 micrometers to about 9 micrometers, such as in a range from about 4 micrometers to about 8 micrometers.

[0075] Returning to FIG. 1, FIG. 1 shows a perspective view of an exemplary interleaf material 10 in accordance with embodiments disclosed herein. In the embodiment shown, interleaf material 10 further comprises a polymer coating material 18 (e.g., a PVA-based coating material as disclosed herein) applied to at least one major surface of paper substrate 12. Polymer coating material 18 may be applied to both major surfaces, i.e., first major surface 14 and second major surface 16.

[0076] FIG. 18 is a cross-sectional edge view of glass substrates 20 arranged in a stack, with interleaf material 10 disposed between adjacent glass substrates in the stack. Each glass substrate comprises a first major surface 22 and a second major surface 24 opposite first major surface 22. Second major surface 24 may be generally parallel with first major surface 22. First major surface 22 and second major surface 24 are joined by an edge surface 26. The number of edge surfaces 26 depends on the shape of glass substrate 20. For example, a rectangular glass substrate 20 comprises four edge surfaces 26. Interleaf material 10 may be arranged to overhang edge surfaces 26 by an overhang distance 28. Atypical overhang distance is about 50 millimeters. However, the overhang distance 28 for one edge surface 26 may not be equal to the overhang distance of another edge surface 26. While the interleaf material shown in FIG. 18 is a coated interleaf material, the interleaf material may be an uncoated but surface treated paper (e.g., coronal discharge treated, laser treated, and/or UV ozone treated).

[0077] Glass substrate 20 may comprise a variety of glass compositions. For example, embodiments disclosed herein include those in which glass substrate 20 comprises an alkali free glass composition, such as comprising S i O2 in a range from about 58 weight percent (wt%) to about 65 wt%, AI2O3 in a range from about 14 wt% to about 20 wt%, B2O3 in a range from about 8 wt% to about 12 wt%, MgO in a range from about 1 wt% to about 3 wt%, CaO in a range from about 5 wt% to about 10 wt%, and SrO in a range from about 0.5 wt% to about 2 wt%. Glass substrate 20 may also comprise an alkali free glass composition, comprising Si O2 in a range from about 58 wt% to about 65 wt%, AI2O3 in a range from about 16 wt% to about 22 wt%, B2O3 in a range from about 1 wt% to about 5 wt%, MgO in a range from about 1 wt% to about 4 wt%, CaO in a range from about 2 wt% to about 6 wt%, SrO in a range from about 1 wt% to about 4 wt%, and BaO in a range from about 5 wt% to about 10 wt%. In addition, glass substrate 20 may comprise an alkali free glass composition, comprising Si O2 in a range from about 57 wt% to about 61 wt%, AI2O3 in a range from about 17 wt% to about 21wt%, B2O3 in a range from about 5 wt% to about 8 wt%, MgO in a range from about 1 wt% to about 5 wt%, CaO in a range from about 3 wt% to about 9 wt%, SrO in a range from about 0 wt% to about 6 wt%, and BaO in a range from about 0 wt% to about 7 wt%. Glass substrate 20 may also comprise an alkali containing glass composition, comprising SiO2 in a range from about 55 wt% to about 72 wt%, AI2O3 in a range from about 12 wt% to about 24 wt%, Na2O in a range from about 10 wt% to about 18 wt%, B2O3 in a range from about 0 wt% to about 10 wt%, K2O in a range from about 0 wt% to about 5 wt%, MgO in a range from about 0 wt% to about 5 wt%, and CaO in a range from about 0 wt% to about 5 wt%, which, in certain embodiments, may also comprise K2O in a range from about 1 wt% to about 5 wt% and MgO in a range from about 1 wt% to about 5 wt%. However, glass substrate 20 is not limited to the preceding glass compositions and may comprise any number of other glass compositions.

[0078] In embodiments, a thickness 30 of glass substrate 20 defined between first major surface 22 and second major surface 24 may be equal to or less than about less than about 5 millimeters, such as in a range from about 0.1 millimeters to about 5 millimeter, including in a range from about 0.1 to 4 millimeters, 0.1 to about 3 millimeters, 0.1 millimeters to about 2 millimeters, 0.1 to about 1 millimeters, 0.1 to about 0.7 millimeters, or 0.1 to about 0.3 millimeters.

Examples

[0079] Embodiments disclosed herein are further illustrated by the following non-limiting examples.

Example 1

[0080] Interleaf materials (e.g., GCIP D uncoated papers), including a paper substrate (NRD, a recycled newsprint paper product manufactured by Delta Paper, Burlington, New Jersey, USA) coated with a PVA-based polymer coating material described herein, were positioned on clean Coming® Eagle XG® glass substrates (having a major surface area of about 10.2 centimeters by 10.2 centimeters) at 54% relative humidity at a temperature of 20°C for eight weeks. The glass substrates were stacked horizontally with interleaf material positioned between adjacent glass substrates, i.e., alternating layers of interleaf material and glass substrates. The stack comprised 1 to 10 glass substrates with a weight placed on top of the stack to mimic pressures seen in an actual shipping configuration. The weight was about 1.8 kilograms and overlayed and encompassed the surface of the stack. The glass substrates and interleaf materials were then separated, and the glass substrates subsequently washed for about one minute with an aqueous solution containing about 1% Semiclean KG (produced by Yokohama Oils & Fats Industry Co., Ltd.) followed by a one-minute rinse in deionized water, repeated twice. Water contact angles of a major surface of the glass substrates contacted with each interleaf material were taken before and after the washing and rinsing steps by measuring the angle that a 2-microliter droplet of water made with the glass surface as determined by a Kruss DSA 100E Drop Shape Analyzer (five measurements per sample) with the results shown in FIG. 19. As can be seen from FIG. 19, water contact angles dropped significantly, from a high of about 80 degrees before washing and rinsing to less than 10 degrees after washing and rinsing. Water contact angles of less than about 10 degrees indicate glass substrate major surfaces with acceptable hydrophilicity.

Example 2

[0081] Interleaf material surfaces were tested for the presence of PDMS using TOF SIMS. In addition to GCIP D uncoated paper and NRD coated paper, a virgin newsprint, labeled NVA (available from Resolute Forest Products, Montreal, Quebec, Canada, and having a basis weight of 48.8 g/m²) and labeled NVRe, a recycled newsprint (available from Alberta Newsprint, Alberta, Canada, and having a basis weight of 45 g/m²) were tested. The designations “A” and “B” indicate opposing surfaces of the interleaf material. The purpose of the testing was to determine if a PVA-based polymer coating as described herein, applied to a paper substrate, formed an adequate barrier to prevent PDMS contamination of glass substrates to which the interleaf material would be applied. The results are shown in FIG. 20 and show a significant reduction in PDMS contamination of interleaf material protected with a PVA-based polymer coating material when compared to an uncoated paper substrate.

Example 3

[0082] Interleaf materials (e.g., uncoated GCIP D), including a paper substrate coated with a PVA-based polymer coating material as described herein, were disposed on glass substrates (having a major surface area of about 10.2 centimeters by 10.2 centimeters) in an atmosphere having a relative humidity of about 54% and at a temperature of about 20°C for a period of one day. Twenty pieces of clean Coming® Eagle XG® glass substrates were interleaved with a paper substrate (NRD, GCIP D, NVRe, and NVA), including a paper substrate (NRD) coated with a PVA-based polymer coating material as described herein, and subjected to a Vibration- Wash test wherein the stack of glass substrates comprising an interleaf material disposed between the glass substrates is vibrated using Telecordia Standard (GR63 Transportation Vibration, Section 4.4.5) for 2 hours at 50% relative humidity. The interleaf material was then removed, and the number of particles on the glass substrates counted before and after washing using a Toray Engineering model HS830 particle counter. The glass substrates were then washed for 1 minute using 1% Semiclean KG (Yokohama Oils and Fats) with ultrasonics at 50°C followed by a one-minute rinse with DI water and the particles recounted after rinsing. As can be seen from FIG. 21, a major surface of each of the glass substrates had fewer than about 0.75 particles per square centimeter having a diameter greater than about 0.75 micrometers (L) after washing, equal to or less than about 0.6 particles per square centimeter having a diameter in a range from about 0.5 to about 1 micrometer (M), and equal to or less than about 0.3 particles per square centimeter having a diameter in a range from about 0.3 to about 0.5 micrometer (S). The coated NRD interleaf material included low molecular weight PVA (with a molecular weight of 6000, 80% hydrolyzed) and high molecular weight PVA (with a molecular weight in a range from about 146,000 to about 186,000, hydrolyzed to a range from about 86% to about 89%).

Example 4

[0083] FIGS. 22 — 24 elaborate on the data from Example 3. FIGS. 22 — 24 show a particle count in excess of 50 particles per square centimeter for the GCIP D paper substrates, uncoated NRD paper, and NRD paper substrate coated with a PVA-based coating material as described herein, and greater than 90 particles per square centimeter with a diameter greater than 1 micrometer. However, after washing, the particle density on the glass surface protected by the PVA-based interleaf material dropped to a level approximately equal to the particle density before vibration testing began. The data illustrate the ease of particle removal after deposition compared to glass protected by an interleaf material without a PVA-based coating material.

[0084] It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A polymer coating material for paper substrates, comprising; polyvinyl alcohol; and for every one-part by weight polyvinyl alcohol, about 0.016 parts by weight to about 0.03 parts by weight of a defoaming agent and about 0.05 parts by weight to about 0.625 parts by weight of a lubricant.

2. The polymer coating material of claim 1, further comprising, for every one-part by weight polyvinyl alcohol, 0.067 parts of an antistatic agent.

3. The polymer coating material of any one of claims 1 to 2, further comprising, for every one- part by weight polyvinyl alcohol, about 0.059 parts by weight to about 0.077 parts by weight of a hydrogen bond breaker.

4. The polymer coating material of any one of claims 1 to 3, further comprising a PDMS suppressant.

5. The polymer coating material of claim 4, wherein the PDMS suppressant is water soluble.

6. The polymer coating material of any one of claims 4 to 5, wherein the PDMS suppressant addition comprises at least one of PEG-Dimethicone, PEG/PPG-dimethicone, or a dimethylsiloxane-ethylene oxide copolymer.

7. An interleaf material for separating glass substrates, comprising: a paper substrate comprising at least one of lignin or cellulose, a first major surface, and a second major surface opposite the first major surface; and a coating disposed on at least one of the first major surface or the second major surface of the paper substrate, the coating comprising: polyvinyl alcohol; and for every one-part polyvinyl alcohol, about 0.016 parts by weight to about 0.03 parts by weight of a defoaming agent and about 0.05 parts by weight to about 0.625 parts by weight of a lubricant.

8. The polymer coating material of claim 7, further comprising a PDMS suppressant.

9. The polymer coating material of claim 8, wherein the PDMS suppressant comprises at least one of PEG-Dimethicone, PEG/PPG-dimethicone, or a dimethylsiloxane-ethylene oxide copolymer.

10. The polymer coating material of claim 8, wherein the PDMS suppressant is water soluble.

11. The interleaf material of any one of claims 7 to 10, wherein the coating comprises about 0.067 parts by weight of an antistatic agent for every one-part by weight polyvinyl alcohol.

12. The interleaf material of claim 11, wherein the antistatic agent comprises poly 4 styrene sulfonate or an amine ethoxylate.

13. The interleaf material of any one of claims 7 to 12, wherein the coating comprises about 0.059 parts by weight to about 0.077 parts by weight of a hydrogen bond breaker for every one- part per weight polyvinyl alcohol.

14. The interleaf material of any one of claims 7 to 13, wherein a thickness of the coating on the at least one of the first major surface or the second major surface is in a range from about 2 micrometers to about 10 micrometers.

15. The interleaf material of any one of claims 7 to 13, wherein the coating is a continuous coat on the at least one of the first major surface or the second major surface.

16. The interleaf material of claim 15, wherein the first major surface and the second major surface are coated with the coating.

17. The interleaf material of any one of claims 7 to 16, wherein the interleaf material is in roll form.

18. The interleaf material of any one of claims 7 to 17, wherein a thickness of the interleaf material is equal to or less than about 200 micrometers.

19. The interleaf material of any one of claims 7 to claim 18, wherein an MD tensile strength of the paper substrate is equal to or greater than about 2.86 kilograms/centimeter of width of the paper substrate when measured according to TAPPI T-494.

20. The interleaf material of any one of claims 7 to 19, wherein a CD tensile strength of the paper substrate is equal to or greater than about 0.7 kilograms/centimeter of width of the paper substrate when measured according to TAPPI T-494.

21. The interleaf material of any one of claims 7 to 20, wherein a tear strength of the paper substrate is equal to or greater than 18 grams for 8 plies when measured according to TAPPI T-414.

22. The interleaf material of any one of claims 7 to 21, wherein a weight of the paper substrate expressed as mass in grams per square meter is in a range from about 40 g/m² to about 120 g/m².

23. A stack of glass substrates, comprising: a plurality of glass substrates arranged in the stack, adjacent glass substrates of the plurality of glass substrates separated by the interleaf material of any one of claims 7 to 22.