JP6237501B2 - Glass paper - Google Patents

Description

  The present invention relates to a glass slip sheet used by being inserted between glass plates.

  In order to protect the glass plate in a distribution process or manufacturing process in which a plurality of glass plates for flat panel displays such as liquid crystal panel displays and plasma panel displays are stacked and stored and transported, glass slip sheets are used.

  A glass plate used as a substrate material for a flat panel display is required to have a higher surface smoothness than a general architectural window glass plate or a vehicle window glass plate. In glass plates for flat panel displays, electronic members are thinly formed on the glass plate surface, so the cleanliness and surface flatness required for the glass plate surface are extremely high compared to glass plates used for other applications. It is expensive. In a glass plate for such a use, if slight damage or contamination occurs due to contact with another glass plate, there is a risk that the performance as a display may be defective.

  Furthermore, in recent years, with the increase in size and mass production of glass plates, in order to increase the conveyance efficiency, the glass plates have been conveyed as much as possible, and the contact area with the glass slip sheet tends to increase. When the contact area and the contact pressure between the glass plate and the glass interleaving paper increase, there is an increased risk of scratches due to foreign matters present in the glass interleaving paper. In addition, there is an increased risk that the resin component and the like contained in the glass interleaving paper will migrate and contaminate the glass plate surface.

  Therefore, high quality has been demanded for glass slip sheets inserted between glass plates.

In order to reduce scratches and contamination caused by the glass interleaving paper, for example, Patent Document 1 discloses glass interleaving paper mainly composed of a pulp raw material. The glass interleaf has a basis weight of 30 to 60 g / m ² , a maximum paper thickness difference between adjacent measurement points is 8 μm or less, and a difference between the maximum value and the minimum value of the paper thickness is 16 μm or less. It is said.

In Patent Document 2, the pulp composition is defined, the compression work is 0.15 J / m ² or more and the compression recovery rate is 50% or more, so that the buffering property is improved and the scratches on the surface of the glass plate are improved. A technique for suppressing the occurrence is disclosed.

JP 2009-184704 A JP 2006-44674 A

  The above-described prior art attempts to prevent scratches, improve adhesion, and improve contamination by improving the physical properties and form of glass interleaving paper. However, since the manufacturing process is increased and new raw materials and manufacturing facilities are required, there is room for further improvement in terms of manufacturing management and productivity.

  The present invention has been made in view of such a situation. This invention makes it a subject to provide the glass interleaving paper which can suppress the damage | wound on the surface of a glass plate in the distribution | circulation process and manufacturing process which laminate | stack and store and convey a plurality of glass plates.

  In order to solve the above problems, the present inventors have found that the occurrence of scratches on the surface of the glass plate can be suppressed by making the formation of the glass interleaving paper uneven, contrary to the conventional approach. As a result, the present invention has been invented. That is, the present invention has the following configuration.

(1) A paper made of cellulose pulp having cellulose pulp as a main component and having a beating degree measured according to JIS P8121 of 200 to 700 mlcsf, and having a basis weight of 10 to 100 g / m ² and a 3D sheet analyzer Glass interleaving paper with a formation index of 15 or less.
(2) Glass interleaving paper as described in said (1) whose thickness is 25-250 micrometers and a density is 0.4-1.2 g / cm < ³ >.

  The glass interleaving paper of the present invention can suppress scratches on the surface of the glass plate in a distribution process in which a plurality of glass plates are stacked and stored and transported.

  Hereinafter, embodiments of the present invention will be specifically described. The present invention is not construed as being limited to these embodiments.

  In order to reduce scratches and contamination caused by glass interleaving paper, the present inventors produce glass interleaving paper under various production conditions, and the relationship between the production conditions of glass interleaving paper and scratches and contamination of the glass plate. We proceeded with examination. As a result, contrary to expectation, it was found that when glass interleaving paper having relatively poor formation and uneven formation is used, the glass plate is prevented from being damaged or contaminated. This result is directed in the opposite direction from conventional industry common sense.

  Therefore, the present inventors have further studied the reason why the above results are generated, and consider the following. In the relatively thick part in the glass interleaving paper produced by the formation unevenness, the cushioning property for the glass plate works depending on the thickness. On the other hand, the contact pressure between the glass interleaving paper and the glass plate is reduced at a relatively thin portion in the glass interleaving paper. It is presumed that by these actions, in any case, the glass plate will work in the direction of improving the damage.

Furthermore, in the glass interleaving paper inferior to the formation, the glass interleaving paper and the glass plate do not come into contact with the entire surface, and a relatively thick part in the glass interleaving paper mainly comes into contact with the glass plate. The present inventors have found that the migration of the resin component in the glass slip sheet is suppressed and the contamination of the glass plate is also improved.
Here, as a contaminant on the surface of the glass plate contained in the glass interleaving paper, a resin component which is an adhesive substance contained in the glass interleaving paper can be mentioned. Many of them are natural impurities such as resins contained in wood. In particular, when the resin content is 0.2% by mass or more in paper, there is a high possibility that the surface of the glass plate is contaminated. Although it is preferable to remove as much as possible by a method such as washing, it is difficult to remove completely.

  Next, the present inventors examined the numerical value of the degree of formation unevenness of the glass interleaving paper that suppresses the occurrence of scratches on the glass plate. As a result, it was found that a 3D sheet analyzer manufactured by M / K systems of the United States was useful for quantifying formation unevenness. Using this 3D sheet analyzer, the formation index of glass interleaving paper, which is effective for suppressing scratches on the glass plate surface, was examined. As a result, it has been found that it is effective to set the formation index of glass interleaving paper to 15 or less, and the present invention has been completed.

  The glass interleaving paper of this embodiment has cellulose pulp as a main component. As a cellulose pulp used for glass interleaving paper, various types can be used alone or in combination of two or more. For example, chemical pulp such as kraft pulp (KP), sulfite pulp (SP), soda pulp (AP); semi-chemical pulp such as semi-chemical pulp (SCP), chemi-ground wood pulp (CGP); groundwood pulp (GP) And mechanical pulps such as thermomechanical pulp (TMP, BCTMP) and refiner grandwood pulp (RGP); non-wood fiber pulps made from straw, miso, hemp, kenaf and the like. In addition to these, synthetic pulp, synthetic fiber, rayon fiber and the like may be blended. The wood used for cellulose pulp may be softwood or hardwood, or may be used as a mixture.

The glass interleaving paper of the present embodiment is a paper made of cellulose pulp having a beating degree measured according to JIS P8121 of 200 to 700 mlcsf.
The beating degree of cellulose pulp according to JIS P8121 is 200 to 700 mlcsf. Here, the beating degree is a Canadian standard freeness according to JIS P8121. By setting the beating degree in the range of 200 to 700 mlcsf, it is possible to have the mechanical strength and workability required for glass interleaving paper. The beating degree is more preferably 400 to 700 mlcsf. In order to adjust the beating degree to 200 to 700 mlcsf, a known method can be used as a method for beating the pulp.

The basis weight of the glass slip sheet is in the range of 10 to 100 g / ^{m 2.} The basis weight is more preferably 35 to 80 g / m ² . A smaller basis weight is preferred because the mass during transportation is reduced, but if the basis weight is less than 10 g / m ² , sufficient buffering properties cannot be imparted. Moreover, since the mass at the time of conveyance is not preferable when a basic weight exceeds 100 g / m < ² >, it is not preferable. The basis weight of glass interleaving paper is measured according to JIS P8124.

The thickness of the glass slip sheet is preferably 25 to 250 μm, and more preferably 60 to 200 μm. It is preferable that the density of the glass slip sheet is 0.4~1.2g / cm ^3, more preferably 0.5~1.1g / cm ^3. In addition, the thickness and density of glass interleaving paper are measured according to JIS P8118.

  As for the glass interleaving paper of this embodiment, the formation index measured with the 3D sheet analyzer is 15 or less. The 3D sheet analyzer is used to quantitatively measure the formation of paper. As a result of repeated studies on a method for quantifying the formation of glass interleaving paper, the 3D sheet analyzer manufactured by M / K systems of the United States of America has good reproducibility, and the formation of glass interleaving paper can be obtained. It has been found that it can be quantified. In this apparatus, the dispersion state of cellulose fibers in paper is converted into an optical image, and the degree of uniformity is quantified by numerically processing the image.

An index obtained by quantifying the formation using this 3D sheet analyzer is the formation index. Specifically, the formation index is calculated as follows.
1) The glass interleaving paper is irradiated with a light source (white light) installed on the drum shaft while the glass interleaving paper is wound around a glass drum and rotated.
2) The light transmitted through the glass interleaving paper is detected by a photodetector, and the intensity of the transmitted light at 100,000 measurement points is classified into 64 intensity classes.
3) Of the 64 intensity classes, the most frequent frequency (peak value) is divided by the number of classes having a frequency of 100 or more, and a value obtained by dividing this by 1/100 is defined as the formation index.
That is, the formation index = (the highest frequency / the number of classes with a frequency of 100 or more) x 1/100
A class with a frequency of less than 100 does not determine the entire glass slip, and is ignored. The smaller the number of classes having the highest frequency and the frequency of 100 or more, the greater the formation index, which can be said to be a uniform glass slip. On the contrary, the formation index becomes smaller as the glass interleaving paper has uneven formation and the formation uniformity is inferior.

  The present inventors examined the relationship between the formation index and the degree of scratches on the surface of the glass plate. As a result, in order to suppress the scratches on the surface of the glass plate to a level where there is no practical problem in a specific application for flat panel display, it is necessary to set the formation index of the glass interleaving paper to 15 or less. I found out. That is, if it is a glass interleaving paper whose formation index measured with a 3D sheet analyzer is 15 or less, it is possible to suppress the scratch resistance to an acceptable level. The formation index of glass interleaving paper is more preferably 10 or less.

As a method of making paper so that the formation index is 15 or less, for example, the following methods are available.
(1) Reduce the amplitude and frequency of the wire shaking device.
(2) Stop the vibration of the wire shaking device.
(3) Increase the number of hydrofoils (counter blades) used in the forming board to increase the initial dewatering amount.
(4) Increase the inlet concentration. For example, if the normal inlet concentration is 0.5%, it is set to about 1%.

  Any of these methods can be used alone or in combination of a plurality of methods as appropriate. The specific conditions vary depending on the type of raw material pulp and the structure of the equipment. It is possible to set appropriate conditions while confirming the relationship.

  It is preferable to add the glass interleaf paper making additive in the present embodiment within a range that does not contaminate or damage the glass plate surface. For example, sizing agents such as aluminum sulfate, sulfuric acid, rosin, styrene / maleic acid, alkenyl succinic anhydride, alkyl ketene dimer, various paper strength enhancers such as polyacrylamide, drainage retention improver, polyamide polyamine epichlorohydrin, etc. Agents, softeners, antistatic agents, antifoaming agents, slime control agents, fillers, dyes and the like can be used. In addition to the above chemicals, it is also possible to apply or impregnate water, glass detergent, polyvinyl alcohol, polyacrylamide, starch or the like on the front and back surfaces of the glass interleaving paper.

  Examples of means for applying or impregnating the above chemicals include, for example, a two-roll size press, a transfer roll coater (gate roll coater, massey coater, KCM coater, champion machine coater, etc.), film transfer size press (shim sizer, blade metering size). Etc.), bill blade coaters (standard coaters, differential coaters, combi coaters), two stream coaters, velvapa coaters, bar coaters, blade coaters, air knife coaters, rod coaters, calendar coaters and the like.

  There are no particular limitations on the manufacturing apparatus and manufacturing conditions for manufacturing the glass interleaving paper of this embodiment, and known manufacturing apparatuses and manufacturing conditions can be appropriately selected and used. For example, paper can be made as a single-layer or multi-layer paper with a long-form former, twin-wire former, circular net former, and inclined former. In addition, a dandy roll may be used for the purpose of appropriately adjusting the formation and controlling the smoothness of the paper surface and the uniformity in the width direction.

  The glass interleaving paper of the present embodiment may be subjected to embossing or creping which is fine irregularities on the surface. The embossing is performed using an embosser or an uneven mold, and is processed into a shape such as a dot shape, a chain line shape, a straight line shape, or a wave shape. Examples of a method of performing the creping treatment include a method of peeling and creping a sheet that has adhered to a press roll in a wet part of a paper machine or a doctor installed on a dryer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these. In addition, the numerical value which shows a mixing | blending is a numerical value of the mass reference | standard of solid content or an active ingredient. Unless otherwise specified, the papers made were processed and tested in accordance with JIS P8111. Details of the formation index measurement, scratch test, and scratch evaluation are as follows.

<Measurement of formation index of glass interleaving paper>
The formation index was measured using a 3D sheet analyzer (M / K 975, manufactured by M / K Systems, USA) which is an optical total of glass interleaving paper. The smaller the formation index indicates that the formation is inferior (there is uneven formation).

<Scratch test on glass plate surface>
In a method in which 310 mm × 310 mm glass interleaving paper is applied to a 300 mm × 300 mm glass plate for flat panel display and pressed at 0.7 MPa for 10 seconds, the glass plate for 300 mm × 300 mm flat panel display is the same, 310 mm × 310 mm Each time the glass slip was pressed once, it was changed to a new one, and the press was repeated 2000 times to obtain a glass plate for flat panel display after the test.

<Evaluation of scratch resistance on glass plate surface>
After the glass plate surface for flat panel displays after the above test was brushed and washed, a spotlight was applied to the glass plate surface, and scratches on the glass plate surface were counted visually and with a microscope. The evaluation of scratchability was performed as follows.
○: 0 to 4 scratches ×: 5 or more scratches

<Example 1>
A commercially available NBKP (conifer bleached kraft pulp) 100% pulp slurry was beaten to 400 mlcsf with a double disc refiner. When making the raw material obtained above with a long paper machine, the amplitude and vibration of the wire shaking device were stopped at the wire part. Using a forming board, a hydrofoil, and a suction box, paper was dehydrated, dried, and a glass interleaving paper of the present invention having a basis weight of 45 g / m ² was obtained.

<Example 2>
Glass interleaving paper was obtained in the same manner as in Example 1 except that it was beaten to 600 mlcsf with a double disc refiner.

<Example 3>
A glass interleaving paper was obtained in the same manner as in Example 1 except that a wire shaking device was used for making paper with a long paper machine and the number of hydrofoil was doubled as in Example 1.

<Comparative Example 1>
A glass interleaving paper was obtained in the same manner as in Example 1 except that it was beaten to 150 mlcsf with a double disc refiner.

<Comparative example 2>
A glass interleaving paper was obtained in the same manner as in Example 1 except that a paper shaker was used for paper making with a long paper machine.

  Table 1 shows the formation index of the produced glass interleaving paper and the evaluation results of the scratchability of the glass plate surface as described above.

  The glass interleaving papers of Examples 1 to 3 had a formation index of 15 or less and good scratch resistance. On the other hand, Comparative Example 1 and Comparative Example 2 had a formation index exceeding 15, and the scratch resistance was poor.

Claims (2)

This paper is made of cellulose pulp having cellulose pulp as a main component and having a beating degree of 200 to 700 mlcsf measured according to JIS P8121, and has a basis weight of 10 to 100 g / m ² and measured with a 3D sheet analyzer. Glass paper with a formation index of 15 or less. The glass interleaving paper according to claim 1, which has a thickness of 25 to 250 µm and a density of 0.4 to 1.2 g / cm ³ .