PAPER

Cross Reference to Related Applications

[0001] This application claims the benefit of a priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No.: 63/190,501, filed on May 19, 2021, the content of which is relied upon and incorporated herein by reference in its entirety.

Field

[0002] The present disclosure relates generally to methods and apparatuses for packing glass sheets with interleaf paper.

Background

[0003] In the packing and transportation of glass sheets, such as glass sheets used for display applications, an interleaf material, such as an interleaf paper, is commonly interposed between glass sheets in order to help protect the sheets from damage. In addition to imparting physical protection, interleaf materials are also designed to minimize the transfer of contaminants onto the glass surface. In addition, such interleaf materials should not impart undesirable levels of electrostatic charge to the glass or undesirably adhere to the glass surface. Moreover, such materials should perform well over time in a variety of different environments, such as in varying temperature and/or humidity conditions. There is a continued need for interleaf materials to meet these and other requirements in a cost effective manner.

SUMMARY

[0004] Embodiments disclosed herein include a method of packing glass sheets. The method includes positioning two or more glass sheets in a packing apparatus. The method also includes disposing a paper interleaf between adjacent glass sheets of the two or more glass sheets. The paper interleaf comprises a total lignin content of at least about 5 weight percent.

[0005] Embodiments disclosed herein also include a packing apparatus. The packing apparatus includes two or more glass sheets positioned therein. The packing apparatus also includes a paper interleaf disposed between adjacent glass sheets of the two or more glass sheets. The paper interleaf comprises a total lignin content of at least about 5 weight percent. [0006] Additional features and advantages of the embodiments disclosed herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the disclosed embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0007] It is to be understood that 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 claimed embodiments. 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 serve to explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a side perspective view of an exemplary packing apparatus in accordance with embodiments disclosed herein;

[0009] FIG. 2 is a side perspective view of a plurality of glass sheets and paper interleafs disposed between adjacent glass sheets in an exemplary packing apparatus in accordance with embodiments disclosed herein;

[0010] FIG. 3 is perspective view of an exemplary glass sheet in accordance with embodiments disclosed herein;

[0011] FIGS. 4 is a perspective view of an exemplary paper interleaf in accordance with embodiments disclosed herein;

[0012] FIG. 5 is a chart showing glass sheet major surface water contact angle after contact aging and after contact aging with subsequent washing for a variety of paper interleafs;

[0013] FIG. 6 is a chart showing glass sheet major surface particle density after contact and after contact with subsequent washing for a variety of paper interleafs;

[0014] FIG. 7 is a chart showing glass sheet zeta potential after contact with a variety of paper interleafs; and

[0015] FIGS. 8 A and AB are charts respectively showing magnesium and aluminum ion surface concentration for a variety of paper interleafs. DETAILED DESCRIPTION

[0016] Reference will now be made in detail to the present preferred 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 may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0017] 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 and/or to the other particular value. Similarly, when values are expressed as approximations, for example 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.

[0018] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0019] 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 actually 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.

[0020] As used herein, the singular forms "a," "an" and "the" include plural referents 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. [0021] As used herein, the term lignin refers to a crosslinked phenolic biopolymer having a weight average molecular weight of at least about 5,000 grams per mole.

[0022] As used herein, the term polysaccharide refers to a polymeric carbohydrate having monosaccharide units bound by glyosidic linkages. Examples include cellulose, amylose, glucan, xylan, mannan, arabinan, and galactan.

[0023] As used herein, the term “two month aging procedure with the paper interleaf’ refers to a test method described herein wherein paper interleafs are disposed between adjacent glass sheets in a weighted stack at about 54% relative humidity at about 20°C for a period of two months following which glass sheets and paper interleafs are separated and the glass sheets subsequently washed for about one minute with an aqueous solution containing about 1% Semiclean KG followed by about a one minute rinse in deionized water repeated twice.

[0024] As used herein, the term “vibration procedure with the paper interleaf’ refers to a test method described herein wherein paper interleafs are disposed between adjacent glass sheets and vibrated using Telecordia Standard following which glass sheets and paper interleafs are separated and the glass sheets subsequently washed for about twelve minutes with an aqueous solution containing about 4% Semiclean KG at about 70 °C and ultrasonics followed by a twelve minutes rinse in deionized water at about 70 °C and ultrasonics.

[0025] As used herein, the term “streaming potential procedure with the paper interleaf’ refers to a test method described herein wherein a paper interleaf is disposed on a glass sheet at about 54% relative humidity at about 20°C for a period of about 24 hours following which the glass sheet and paper interleaf are separated.

[0026] As used herein, the term “fogging procedure with the paper interleaf’ refers to a test method described herein wherein a hole-punched paper interleaf is disposed on a glass sheet at about 54% relative humidity at about 20°C for a period of about 24 to 48 hours after which the paper interleaf is removed and the glass sheet is exposed to steam, following which the glass sheet is subsequently washed for about one minute with an aqueous solution containing about 1% Semiclean KG followed by about a one minute rinse in deionized water, followed by an additional exposure of the glass sheet to steam.

[0027] As used herein, the term “Mura defects” refer to nonuniformities visible on a surface as known to persons having ordinary skill in the art and described, for example, in U.S. patent no. 5,917,935.

[0028] FIG. 1 shows a side perspective view of an exemplary packing apparatus 100 in accordance with embodiments disclosed herein. Packing apparatus 100 includes cover 102, support member 104, seat 106, pallet 108, and at least one support post 110. Packing apparatus 100 is configured to enclose a plurality of glass sheets positioned therein.

[0029] In certain exemplary embodiments, cover 102 can comprise a metal, a polymer, a polymer composite, and or metal/polymer laminate. In certain exemplary embodiments, support member 104, seat 106, pallet 108, and /or support post 110 can comprise a metal, such as aluminum or stainless steel, or a polymer composite.

[0030] FIG. 2 shows a side perspective view of a plurality of glass sheets 10 and paper interleafs 20 disposed between adjacent glass sheets 10 in an exemplary packing apparatus 100 in accordance with embodiments disclosed herein Glass sheets 10 and paper interleafs 20 are positioned on cushioning member 112, which is in turn positioned over seat 106, wherein cushioning member 112 may be adhered to seat 106 with a suitable adhesive. Cushioning member 112 may, for example, comprise a resilient polymeric material, such as a material comprising ethylene-propylene-diene terpolymer.

[0031] FIG. 3 shows a perspective view of an exemplary glass sheet 10 in accordance with embodiments disclosed herein. Glass sheet 10 has a first major surface 12, an opposing second major surface 14 extending in a generally parallel direction to the first major surface 12 (on the opposite side of the glass sheet 10 as the first major surface 12) and an edge surface 16 extending between the first major surface 12 and the second major surface 14 and extending in a generally perpendicular direction to the first and second major surfaces 12, 14. [0032] FIG. 4 shows a perspective view of an exemplary paper interleaf 20 in accordance with embodiments disclosed herein. Paper interleaf 20 has a first major surface 22 and an opposing second major surface 24 extending in a generally parallel direction to the first major surface 22 (on the opposite side of the paper interleaf 20 as the first major surface 22).

[0033] Embodiments disclosed herein include those in which paper interleaf 20 comprises a total lignin content of at least about 5 weight percent, such as at least about 10 weight percent, and further such as at least about 15 weight percent, and yet further such as at least about 20 weight percent, including from about 5 weight percent to about 40 weight percent, and further including from about 10 weight percent to about 35 weight percent, and yet further including from about 20 weight percent to about 30 weight percent.

[0034] Embodiments disclosed herein include those in which paper interleaf 20 comprises a total polysaccharide content of no more than about 80 weight percent, such as no more than about 75 weight percent, and further such as no more than about 70 weight percent, and yet further such as no more than about 65 weight percent, including from about 40 weight percent to about 80 weight percent, and further including from about 45 weight percent to about 75 weight percent, and yet further including from about 50 weight percent to about 70 weight percent.

[0035] Table 1 summarizes the content of five paper interleafs, the first two of which are comparative paper interleafs and the last three of which are exemplary paper interleafs in accordance with embodiments disclosed herein. The comparative interleafs are set forth in Table 1 as “Paper 1” and “Paper 2” and are, specifically, commercially available polysaccharide-based paper interleafs. The exemplary paper interleafs are set forth in Table 1 as “Paper 3,” “Paper 4,” and “Paper 5” and are, specifically, commercially available recycled newsprint (in the case of “Paper 3”) and commercially available virgin newsprint (in the case of “Paper 4” and “Paper 5”). Composition of the papers was determined by submitting about 30 grams of each paper to a bulk lignocellulosic analysis under the Celignis Biomass Analysis Laboratory P10 protocol.

[0036] Table 1 :

[0037] Glass sheet 10 may comprise a variety of glass compositions. For example, embodiments disclosed herein include those in which glass sheet 10 comprises an alkali free glass composition, comprising 58-65 weight percent (wt%) SiCh, 14-20wt% AI2O3, 8-12wt% B2O3, l-3wt% MgO, 5-10wt% CaO, and 0.5-2wt% SrO. Glass sheet 10 may also comprise an alkali free glass composition, comprising 58-65wt% S1O2, 16-22wt% AI2O3, l-5wt% B2O3, l-4wt% MgO, 2-6wt% CaO, l-4wt% SrO, and 5-10wt% BaO. In addition, glass sheet 10 may comprise an alkali free glass composition, comprising 57-61wt% S1O2, 17-21wt% AI ₂ O ₃ , 5-8wt% B ₂ O ₃ , l-5wt% MgO, 3-9wt% CaO, 0-6wt% SrO, and 0-7wt% BaO. Glass sheet 10 may also comprise an alkali containing glass composition, comprising 55-72wt% S1O2, 12-24wt% AI2O3, 10-18wt% Na20, 0-10wt% B2O3, 0-5wt% K2O, 0-5wt% MgO, and 0- 5wt% CaO, which, in certain embodiments, may also comprise l-5wt% K ₂ O and l-5wt% MgO.

[0038] In certain exemplary embodiments, glass sheet 10 has a thickness of less than about 1 millimeter, such as a thickness ranging from about 0.1 millimeters to about 1 millimeter, including from about 0.2 millimeters to about 0.8 millimeters, and further including from about 0.3 millimeters to about 0.7 millimeters, including about 0.5 millimeters.

[0039] Examples

[0040] Embodiments disclosed herein are further illustrated by the following non-limiting examples.

[0041] Example 1:

[0042] A two month aging procedure with a paper interleaf was conducted wherein paper interleafs were disposed between clean Corning® Eagle XG® glass sheets (having a major surface area of about 4 inches by 4 inches) in a weighted stack of about 5 kilograms at about 54% relative humidity at about 20°C for a period of two months. The glass sheets and paper interleafs were then separated and the glass sheets 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 about a one minute rinse in deionized water repeated twice. This procedure was conducted for five paper interleafs, specifically: Paper 1, Paper 3, Paper 4, and Paper 5 as described above with reference to Table 1, and an additional commercially available virgin newsprint (“Paper 6”). Water contact angles of a major surface of glass sheets contacted with each paper interleaf were taken before and after the washing and rinsing steps by measuring the angle that about a 2 microliter droplet of water makes with the glass surface as determined by the Kruss DSA 100E Drop Shape Analyzer (five measurements per sample), with the results shown in FIG. 5. As can be seen from FIG. 5, water contact angles of less than about 10 degrees were observed for all of the glass sheets after the washing and rinsing steps. Water contact angles of less than about 10 degrees indicate glass sheet major surfaces with acceptable hydrophilicity.

[0043] Example 2:

[0044] A vibration procedure with a paper interleaf was conducted wherein paper interleafs were disposed between adjacent Corning® Eagle XG® glass sheets (20 total sheets, each having a major surface area of about 4 inches by 4 inches) and vibrated using Telecordia Standard (GR63 Transportation Vibration, Section 4.4.5). The glass sheets and paper interleafs were then separated and the glass sheets subsequently washed for about twelve minutes with an aqueous solution containing about 4% Semiclean KG at about 70 °C and ultrasonics followed by a twelve minutes rinse in deionized water at about 70 °C and ultrasonics. This procedure was conducted for four paper interleafs (with two experimental runs per interleaf), specifically: Paper 1, Paper 3, Paper 4, and Paper 5 as described above with reference to Table 1. In addition, for each paper interleaf, the vibration procedure was conducted at about 20%, about 50%, and about 80% relative humidity at about 20°C. After each experimental run, particles having a diameter of greater than about 0.3 microns were counted on a major surface of each glass sheet before and after the washing and rinsing steps using a Toray Engineering model HS830 particle counter with the results shown in FIG. 6.

As can be seen from FIG. 6, a major surface of each of the glass sheets has fewer than about 30 particles per square centimeter having a diameter of greater than about 0.3 microns after washing.

[0045] Example 3:

[0046] A streaming potential procedure with a paper interleaf was conducted wherein paper interleafs were deposed on clean Corning® Eagle XG® glass sheets (having a major surface area of about 2 inches by 2 inches) at about 54% relative humidity at about 20°C for a period of about 24 hours. This procedure was conducted for four paper interleafs, specifically: Paper 1, Paper 3, Paper 4, and Paper 5 as described above with reference to Table 1. The glass sheets and paper interleafs were then separated and the glass surface was analyzed for zeta potential using the Anton Paar SurPass system for electrokinetic analysis with the results shown in FIG. 7. This system measures glass surface zeta potential via the streaming potential and streaming current methods as a function of pH. As can be seen from FIG. 7, a major surface of each of the glass sheets has a zeta potential at a pH of about 3 ranging from about -40 mV to about -80 mV, a zeta potential at a pH of about 7 ranging from about -70 mV to about -110 mV, and a zeta potential at a pH of about 11 ranging from about -80 mV to about -120 mV and is indistinguishable from the control. Such zeta potentials indicate acceptable levels of electrostatic repulsion between the glass sheets and the paper interleafs.

[0047] Example 4:

[0048] A fogging procedure with a paper interleaf was conducted wherein paper having a major surface area of about 4 inches by 4 inches and hole-punched with about 0.25 inch diameter holes were disposed on Corning® Eagle XG® glass sheets (having a major surface area of about 4 inches by 4 inches) at about 54% relative humidity at about 20°C for a period of about 24 to 48 hours. The glass sheet was then separated from the paper and exposed to a short burst of steam. Next, the glass sheets were subsequently washed for about one minute with an aqueous solution containing about 1% Semiclean KG at about 50°C followed by about a one minute rinse in deionized water repeated twice. This step was followed by an additional exposure of the glass sheets to a short burst of steam This procedure was conducted for two paper interleafs, specifically: Paper 1 and Paper 3 as described above with reference to Table 1. In the case of the Paper 3 interleaf, while a major surface of the glass sheets showed visible Mura defects after being exposed to the first burst of steam, these visible defects were not present subsequent to exposure to the second burst of steam for both of the Paper 1 and Paper 3 interleafs.

[0049] Example 5:

[0050] Paper 1, Paper 3, Paper 4, Paper 5, and Paper 6 interleafs (each having major surface areas of about 1 inch by 1 inch) were each analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS) with the results for normalized magnesium and aluminum ion intensity shown, respectively, in FIGS. 8A and 8B. Specifically, a IONTOF ToF-SIMS NCS with M6 analyzer was used (ion beam characteristics: Bi3+, mass spectrometry mode, 400 micron beam defining aperture, 200 micron by 200 micron random rastered area with a 128x128 pixel density, 350 microsecond cycle time, and pulsed current of about 0.7-0.8 pA) wherein a low energy flood gun used for charge compensation during analysis. The analysis time was about 3 minutes, which included 31 beam scans and a total ion dose of about 1.94 x 10 ¹¹ ions per square centimeter. Peak area was normalized by the sum all ions detected, with four analyses per interleaf (positive mode) wherein plots shown are averaged from the four analyses and error bars represent standard deviations. As can be seen from FIGS. 8A and 8B, a major surface of each of the Paper 3-Paper6 interleafs had a normalized magnesium ion intensity of less than about 2 and a normalized aluminum ion intensity of less than about 2. Magnesium and aluminum are indicative of the presence of talc and aluminum silicate.

[0051] In certain exemplary embodiments, after a two month aging procedure with the paper interleaf and washing, a major surface of the glass sheets has a water contact angle of less than about 10 degrees, such as less than about 8 degrees, and further such as less than about 6 degrees, and yet further such as less than about 4 degrees, such as from about 1 degree to about 10 degrees, and further such as from about 2 degrees to about 8 degrees, and yet further such as from about 3 degrees to about 6 degrees. [0052] In certain exemplary embodiments, after a vibration procedure with the paper interleaf, a major surface of the glass sheets has less than about 30 particles, such as less than about 25 particles, and further such as less than about 20 particles, and yet further such as less than about 15 particles, including from about 5 particles to about 30 particles, and further including from about 10 particles to about 25 particles having a diameter of greater than about 0.3 microns particles per square centimeter after washing.

[0053] In certain exemplary embodiments, after an analysis of the streaming potential of the glass surface before or after contact with the paper interleaf, a major surface of the glass sheets has a zeta potential at a pH of about 3 ranging from about -40 mV to about -80 mV, such as from about -45 mV to about -75 mV, a zeta potential at a pH of about 7 ranging from about -70 mV to about -110 mV, such as from about -75 mV to about -105 MV, and a zeta potential at a pH of about 11 ranging from about -80 mV to about -120 mV, such as from about -85 mV to about -115 mV.

[0054] In certain exemplary embodiments, after a fogging procedure with the paper interleaf, a major surface of the glass sheet shows no visible Mura defects.

[0055] In certain exemplary embodiments, a major surface of the paper interleaf has a normalized magnesium ion intensity of less than about 2, such as less than about 1.5, including from about 0.5 to about 2, and further including from about 1 to about 1.5, and a normalized aluminum ion intensity of less than about 2, such as less than about 1.5, including from about 0.5 to about 2, and further including from about 1 to about 1.5 as determined by time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0056] Embodiments disclosed herein can enable cost effective packing and transportation of glass sheets, such as glass sheets used for display applications, having major surfaces with, for example, acceptable hydrophilicity, reduced submicron particle densities, acceptable streaming potential, no visible Mura defects, and reduced talc contamination.

[0057] 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.