阅读说明：本技术 玻璃衬纸及其制造方法 (Glass lining paper and method for manufacturing same ) 是由 萩原浩一 于 2019-08-27 设计创作，主要内容包括：本发明提供一种玻璃衬纸以及其制造方法,其能够降低玻璃板的腐蚀的发生。一种玻璃衬纸,其以化学浆为主成分,钠含量为0.03～1.0质量％,克重为10～300g/m～2,其中,阔叶树纸浆在前述化学浆中所占的比例为10质量％以上。另外,一种前述玻璃衬纸的制造方法,其特征在于,在前述化学浆的制造工序以及抄纸工序的至少一个工序中,使用含有钠的水。另外,一种前述玻璃衬纸的制造方法,其特征在于,在前述化学浆的制造工序、抄纸工序以及抄纸后的工序的至少一个工序中,添加含有钠的化合物。(The invention provides a glass lining paper and a manufacturing method thereof, which can reduce the occurrence of corrosion of a glass plate. A glass lining paper which comprises a chemical pulp as a main component, sodium in an amount of 0.03 to 1.0 mass%, and a basis weight of 10 to 300g/m 2 Wherein the proportion of the hardwood pulp in the chemical pulp is 10 mass% or more. In addition, the method for manufacturing the glass lining paper is characterized in that water containing sodium is used in at least one of the chemical pulp manufacturing step and the paper making step. Further, the method for producing the glass lining paper is characterized in that the chemical pulp is added in at least one of the production process, the paper-making process and the post-paper-making processA sodium-containing compound.)

1. A glass lining paper which comprises a chemical pulp as a main component, sodium in an amount of 0.03 to 1.0 mass%, and a basis weight of 10 to 300g/m²Wherein the proportion of the hardwood pulp in the chemical pulp is 10 mass% or more.

2. A method for manufacturing the glass lining paper according to claim 1, wherein water containing sodium is used in at least one of the chemical pulp manufacturing step and the paper making step.

3. A method for manufacturing the glass lining paper according to claim 1, wherein a compound containing sodium is added in at least one of the steps of the chemical pulp manufacturing step, the paper making step, and the post-paper making step.

4. The method for manufacturing glass lining paper according to claim 3, wherein said sodium-containing compound is sodium sulfate.

Technical Field

The present invention relates to a glass lining paper to be inserted between glass plates and a method for manufacturing the same.

Background

In recent years, the glass sheets have been used in many applications, and the quality of the glass lining paper has been required to be strict. For example, in a glass substrate used for a flat panel display such as a liquid crystal display or a touch panel, since fine electronic components are formed on the surface of the glass substrate, if the surface is slightly damaged or contaminated, it becomes a cause of defects such as disconnection, and product defects are caused. Therefore, the surface of the glass substrate is required to have high transparency.

As glass substrates are increased in size and mass production, glass substrates are often stacked and conveyed to improve conveyance efficiency. When the glass substrates are stacked, the contact pressure between the glass lining paper and the glass substrates increases, and therefore, the glass substrates are contaminated by trace components, foreign matters, and the like in the glass lining paper, or the probability of giving a trouble increases. On the other hand, with the high precision processing of the glass substrate, the surface of the glass substrate is required to have a higher transparency. Under the above circumstances, the level of demand for quality of glass lining paper is also continuously increasing.

Contamination of the surface of the glass substrate is considered to have several causes. Soda glass used for a glass substrate for a touch panel has a problem that if a contact period between a glass lining paper and a surface of the glass substrate becomes long, a paper pattern or corrosion (tarnish) is likely to occur on the surface of the glass substrate. The etching is a phenomenon in which soluble components such as sodium ions in a glass substrate undergo an ion exchange reaction with hydrogen ions derived from water or the like to etch the surface of the glass substrate to make it rough, and eluted components react with acidic gases such as carbon dioxide in the air to precipitate reaction products or the like, thereby causing white haze to be seen on the surface.

In order to prevent such corrosion of the surface of the glass substrate, various methods have been proposed. For example, patent document 1 discloses a slip sheet for glass plates, which contains zeolite to suppress the occurrence of corrosion of the glass plates, and which makes the glass plates water repellent and does not cause adhesion of paper stains.

[ Prior art documents ]

[ patent document ]

Patent document 1: japanese patent laid-open No. 7-41034.

Disclosure of Invention

[ problems to be solved by the invention ]

However, the method of blending zeolite described in patent document 1 has an insufficient effect on corrosion.

The present invention has been made in view of the above circumstances. That is, an object of the present invention is to provide a glass lining paper and a method for manufacturing the same, which can reduce the occurrence of corrosion of glass plates.

[ means for solving problems ]

The present inventors have studied the influence of metal ions generated by corrosion in order to solve the above problems, and have found that glass interleaving paper having a large sodium content is less corroded and that the glass interleaving paper containing hardwood pulp tends to be less corroded when compared with the case where hardwood pulp is not contained. The present invention has been made based on this finding. That is, the present invention has the following configuration.

(1) A glass lining paper which comprises a chemical pulp as a main component, sodium in an amount of 0.03 to 1.0 mass%, and a basis weight of 10 to 300g/m²Wherein the proportion of the hardwood pulp in the chemical pulp is 10 mass% or more.

(2) A method for producing a glass lining paper according to the above (1), wherein water containing sodium is used in at least one of the chemical pulp production step and the paper making step.

(3) A method for producing a glass lining paper according to the above (1), wherein a sodium-containing compound is added in at least one of the chemical pulp production step, the paper-making step, and the post-paper-making step.

(4) The method for producing glass lining paper according to the above (3), wherein the sodium-containing compound is sodium sulfate.

[ Effect of the invention ]

According to the glass lining paper, the occurrence of corrosion of glass plates can be reduced. Further, according to the method for manufacturing a glass lining paper of the present invention, the glass lining paper can be manufactured.

Detailed Description

The present invention will be specifically explained below. The embodiments shown below are merely examples, and the present invention is not limited to these embodiments and should not be construed as being limited to these embodiments.

The glass lining paper of the present embodiment contains chemical pulp as a main component and sodium. Hereinafter, each component will be described.

(chemical pulp)

The glass lining paper (hereinafter, also referred to as "lining paper" as appropriate) of the present embodiment contains chemical pulp as a main component. Here, the chemical pulp as a main component means that the chemical pulp exceeds 50 mass% with respect to the mass of the backing paper. The chemical pulp is preferably 70 mass% or more, and more preferably 90 mass% or more, with respect to the mass of the interleaving paper. The chemical pulp is cellulose pulp produced by a chemical process, and examples thereof include Kraft Pulp (KP), Sulfite Pulp (SP), and Alkaline Pulp (AP).

Chemical pulp (wood pulp) using wood as a raw material includes softwood pulp or hardwood pulp. The present inventors have found that when hardwood pulp is blended as chemical pulp, corrosion tends to be less likely to occur, as compared with a case where hardwood pulp is not blended as chemical pulp. The reason why the corrosion is less likely to occur when hardwood pulp is blended is considered to be as follows. When the glass plate and the interleaving paper are stacked and stored, wrinkles occur due to moisture absorption and extension of the interleaving paper under the influence of high-humidity environments such as summer, a gap is formed between the glass plate and the interleaving paper, and high-humidity air directly contacts the glass plate. The air with high humidity is likely to cause corrosion described later. Therefore, if the paper is a paper which hardly causes wrinkles even if it absorbs moisture, the occurrence of corrosion can be suppressed. Since the hardwood pulp has a shorter fiber length than the softwood pulp, and if the blending amount of the hardwood pulp is large, the texture of the paper becomes excellent, wrinkles caused by moisture absorption can be suppressed, occurrence of a gap between the glass plate and the mount paper can be prevented, and the amount of corrosion can be reduced.

That is, in the mount of the present embodiment, the proportion of the hardwood pulp in the chemical pulp is 10 mass% or more in order to reduce the amount of corrosion. The proportion of the hardwood pulp in the chemical pulp is preferably 40 mass% or more, and more preferably 70 mass% or more.

Further, as the wood pulp, Kraft Pulp (KP) having a low content of adhesive natural resin components derived from wood is preferable. Further, as the chemical pulp not using wood as a raw material, for example, non-wood fiber pulp using paper mulberry, tree twig, hemp, kenaf, or the like as a raw material is used.

Examples of pulps other than chemical pulp include semi-chemical pulp (SCP), Chemical Ground Pulp (CGP), and other semi-chemical pulps; mechanical pulps such as Groundwood Pulp (GP), thermomechanical pulp (TMP, BCTMP), Refined Groundwood Pulp (RGP), and the like. The glass liner paper of the present embodiment may be mixed with 1 or 2 or more kinds of pulp other than chemical pulp.

Since waste pulp generally contains a large amount of sticky foreign matter, impurities, and resin components, raw pulp is preferable as a pulp raw material for the liner paper as compared with waste pulp.

The preferred beating degree of the chemical pulp is 200-700 mlcsf. The tapping degree is the Canadian standard freeness (Canadian standard freeness) of JIS P8121. The chemical pulp has a beating degree in the range of 200 to 700mlcsf, and thus can have mechanical strength and processability required for the backing paper. When the degree of beating of the chemical paste is less than 200mlcsf, the density of the interleaving paper tends to be high, and the cushioning property tends to be low, so that the glass surface may be easily damaged. On the other hand, when the degree of beating of the chemical pulp is higher than 700mlcsf, the paper strength is weakened, and therefore, there is a risk of breakage during distribution or in the production process. The degree of beating of the chemical pulp is more preferably 350 to 600 mlcsf. As the method of beating the pulp, a known method can be used.

(Corrosion of glass plate)

The following 2 types of mechanisms for the occurrence of corrosion of glass plates have been considered. That is, when water droplets adhere to the surface of the glass plate, a small amount of sodium ions in the glass are dissolved into the water to form sodium hydroxide on the surface of the glass plate, and the surface of the glass plate is etched and roughened, thereby making the glass plate white and turbid. When the water droplets on the surface of the glass sheet evaporate, sodium ions react with carbon dioxide in the air to form sodium carbonate or sodium bicarbonate, which adheres to the surface of the glass sheet and turns white and turbid.

In the case of the above-described conventional corrosion, the cloudiness of the glass plate can be confirmed using a fluorescent lamp of general brightness. However, it is known that micro (micro) etching, which is a different type from the above-described conventional etching, is present on a glass substrate for a touch panel or the like. Such a slight corrosion cannot be visually recognized unless a high-brightness lamp is used and the lamp is inspected in a dark room. In a glass substrate for a touch panel, etc., fine electronic components and the like are formed on the surface of the glass substrate. Therefore, even such a minute corrosion, which cannot be visually recognized by a darkroom inspection without using a high-brightness lamp, causes a defect such as disconnection, and causes a product defect, which causes a problem.

(sodium)

The present inventors have found that when the interleaving paper contains a predetermined amount of sodium, the above-described fine corrosion tends to be less likely to occur. That is, the sodium content of the interleaving paper of the present embodiment is 0.03 to 1.0 mass%. When the sodium content is 0.03 mass% or more, the amount of corrosion can be reduced. On the other hand, if the sodium content exceeds 1.0 mass%, there is a fear that sodium salt is precipitated in the interleaving paper to contaminate the glass sheet. The sodium content in the lining paper is more preferably 0.05 to 0.5 mass%, and still more preferably 0.1 to 0.3 mass%. The sodium content in the backing paper can be determined by measuring the ash content of the backing paper and further measuring the sodium content in the ash via fluorescent X-ray analysis.

The reason why the glass sheet causes the above-mentioned minute corrosion and the clear explanation of the mechanism are to be studied in the future, but it is considered that the reason is an ion exchange reaction between sodium in the glass and hydrogen ions of water. Therefore, the minute corrosion is considered to be corrosion caused by the following mechanism.

A soda glass plate is generally used as a glass substrate for a touch panel. The soda glass plate has a protective film for preventing flaws (damage) made of sulfate on the surface of the glass plate. The flaw prevention protective film is formed by: in the production of a glass sheet, sulfurous acid gas is blown onto the surface of the glass sheet to react sodium in the glass sheet with the sulfurous acid gas, thereby generating sodium sulfate on the surface of the glass sheet. When the sulfurous acid gas is blown, sodium in the glass sheet bleeds (moves) to the vicinity of the surface, and thus the vicinity of the surface of the glass sheet becomes a state where the amount of sodium is deficient. Presumably, this causes minute corrosion.

However, if the content of sodium in the interleaving paper is large, the effect of suppressing the sodium ions in the glass plate from oozing (moving) out to the interleaving paper is obtained. Further, the effect of moving the sodium ions in the interleaving paper to the sodium deficient portion near the surface of the glass sheet via the protective film for preventing flaws formed of sodium sulfate is also obtained. As a result, the amount of sodium ions present in the glass sheet is stabilized, and the ion exchange reaction between the sodium ions and the hydrogen ions of the water vapor in the interleaving paper or in the air is suppressed. Accordingly, it is presumed that the occurrence of corrosion is reduced without increasing the amount of hydrogen ions present in the glass sheet.

As a method for suppressing the sodium content in the liner paper to 0.03 to 1.0 mass%, there is a method (method 1) in which water containing sodium is used in at least 1 of the chemical pulp production step and the paper making step; a method in which a sodium-containing compound is added to at least 1 step of the steps of producing a chemical pulp, papermaking and post-papermaking (method 2).

The method 1 can adjust the sodium content in the finally obtained backing paper by appropriately controlling the sodium content in the water used in at least 1 of the chemical pulp production step and the papermaking step. Sodium is a component that is normally contained in water. Soft water is relatively low in sodium content, and hard water is relatively high in sodium content. The hardness of the water containing sodium is preferably 70 to 500(mg/l), more preferably 120 to 400 (mg/l). The conductivity of water is preferably 14 to 100mS/m, and more preferably 24 to 33 mS/m. The water containing sodium can be used in both the chemical pulp production process and the papermaking process, or in either process. When sodium is dissolved in water used in the chemical pulp production step or the paper making step, the carboxyl group contained in the chemical pulp forms a salt with a metal ion, and sodium can be held in the chemical pulp. Further, since the paper is produced by drying wet paper, a certain amount of sodium in the water can be retained.

As the 2 nd method, there is a method (internal addition method) of adding a sodium-containing compound to a raw material in at least 1 step of a chemical pulp production step and a papermaking step; a method (aqueous method) in which water containing a sodium-containing compound is dissolved or dispersed in at least 1 of the steps of producing a chemical pulp and papermaking; and a method (coating method) of applying an aqueous solution in which a sodium-containing compound is dissolved or dispersed to the surface of a liner paper in a step after paper making. Among these, a coating method capable of more efficiently containing sodium is preferable.

(sodium sulfate)

In the method 2, the compound containing sodium is preferably sodium sulfate (mirabilite, Na)₂SO₄). Sodium sulfate is used as a raw material of glass in some cases.

The amount of sodium sulfate added to the mount is preferably 0.03 to 1.5 mass%, more preferably 0.05 to 1.0 mass%, and still more preferably 0.1 to 0.6 mass%. If the amount of sodium sulfate added exceeds 1.5 mass%, the problem of precipitation of sodium sulfate particles on the surface of the glass plate may occur.

As described above, by specifying the ratio of the hardwood pulp in the chemical pulp and the sodium content in the interleaving paper, the occurrence of corrosion of the glass sheet can be reduced.

(paper-making drugs)

As the paper-making chemicals used for making the interleaving paper, various known chemicals can be used as long as the glass surface is not contaminated. Examples of the chemicals for papermaking include paper strength enhancers such as polyacrylamide, water resistance agents such as polyamide polyamine epichlorohydrin, softeners, antistatic agents, antifoaming agents, slime control agents, fillers, and dyes. Since these papermaking chemicals are problematic in that they contaminate the glass sheet, the total amount is preferably 0.1 mass% or less even when added.

(method for producing glass lining paper)

The method for producing the interleaving paper is not particularly limited, and paper can be produced by selecting appropriate paper-making conditions using various paper-making machines. The paper machine may be specifically exemplified by a fourdrinier wire forming machine, a twin wire forming machine, a cylinder forming machine, an inclined forming machine, and the like. The layer structure of the lining paper can be a single layer or a plurality of layers. The method 1 or 2 can be used to control the sodium content in the interleaving paper to 0.03 to 1.0 mass%.

(characteristics of glass liner paper)

The smaller grammage of the interleaving paper is preferable because the smaller weight is small in transportation, but when the grammage is too small, sufficient cushioning property of the glass sheet cannot be provided. On the other hand, the grammage of the interleaving paper is preferably large to some extent in view of the cushioning property, but if it is too large, the mass during transportation increases, which is not preferable. The weight of the interleaving paper is 10-300 g/m in consideration of the balance between the cushioning property and the transportation easiness and the application². Further, the mount weight of the mount paper is more preferably 30 to 80g/m²。

The thickness of the backing paper is preferably 25 to 250 μm from the viewpoint of cushioning properties and workability. The density of the lining paper is preferably 0.4 to 1.2g/cm³。

The pH (JIS P8133-2) of the lining paper is preferably neutral.

The interleaving paper of the present embodiment is used for protecting a glass substrate for a touch panel, a glass substrate for a flat panel display such as a liquid crystal display, an organic electroluminescence display, or a plasma display, when the glass substrate is stored and transported while being stacked.

[ examples ]

The present invention will be described in detail with reference to examples, but the present invention is not limited thereto. The blending ratio shown is a mass-based ratio (% by mass) of the solid component or the effective component. In addition, unless otherwise specified, the produced paper was treated according to JIS P8111 and then subjected to measurement and evaluation tests.

Examples 1 to 4 and comparative examples 1 to 2

The materials used in the examples and comparative examples are as follows.

Broadleaf bleached kraft pulp (LBKP): commercially available bleached kraft pulp from broadleaf trees.

Bleached softwood kraft pulp (NBKP): commercially available bleached softwood kraft pulp.

Sodium sulfate: anhydrous neutral sodium sulfate manufactured by Tosoh corporation.

Measurement of the conductivity of water, according to JIS K0130: 2008, measurement was carried out using a portable conductivity meter ES-51 manufactured by HORIBA, Inc. (HORIBA).

[ example 1]

Using 80% of commercially available LBKP (broadleaf bleached kraft pulp) and 20% of commercially available NBKP (softwood bleached kraft pulp) (beating degree of 450mlcsf), papermaking was carried out using a fourdrinier machine with water having a conductivity of 25mS/m and without adding papermaking chemicals. Drying after papermaking to obtain the gram weight of 40g/m²The glass lining paper of (1). The sodium content of the obtained glass lining paper was 0.05%.

[ example 2]

Glass interleaving paper was obtained in the same manner as in example 1, except that water having a conductivity of 3mS/m was used and a sodium sulfate solution was applied by a size press so that the amount of sodium sulfate added to the interleaving paper became 0.3%. The sodium content of the obtained glass lining paper was 0.10%.

[ example 3]

Glass interleaving paper was obtained in the same manner as in example 2, except that the amount of sodium sulfate added to the interleaving paper was changed to 0.5%. The sodium content of the obtained glass lining paper was 0.18%.

[ example 4]

Glass interleaving papers were obtained in the same manner as in example 3, except that base paper pulp (degree of beating 450mlcsf) of 40% of commercially available LBKP (hardwood bleached kraft pulp) and 60% of commercially available NBKP (softwood bleached kraft pulp) was used as raw material pulp. The sodium content of the obtained glass lining paper was 0.18%.

Comparative example 1

Glass interleaving paper was obtained in the same manner as in example 2, except that sodium sulfate was not added. The sodium content of the obtained glass liner paper was 0.01%.

Comparative example 2

Glass interleaving papers were obtained in the same manner as in example 3, except that commercially available NBKP (softwood bleached kraft pulp) 100% base stock pulp (degree of beating 450mlcsf) was used as the raw stock pulp. The sodium content of the obtained glass lining paper was 0.18%.

(evaluation content)

The evaluation contents of the obtained glass lining paper are as follows.

Sodium content in lining paper

The ash content of the glass lining paper was determined in accordance with JIS P8251. The sodium content (% by mass) in the obtained ash was obtained from the measured value of the mass concentration by using a fluorescence X-ray analyzer (JSX-3600M, manufactured by Nippon electronics Co., Ltd.). The sodium content m (mass%) in the glass lining paper was determined by the following formula (1).

m＝a×b (1)

Here, m: sodium content (mass%).

a: ash content (mass%) of glass lining paper.

b: sodium content (mass%) in ash.

Evaluation of Corrosion of glass plate

A glass plate for a touch panel of 200mm × 200mm was placed on a glass liner of 210mm × 210mm, and 3 sets of the glass plate were alternately stacked in combination, and a 1kg weight was placed thereon to apply pressure, and the glass plate was allowed to stand at 50 ℃ and 90% RH for 4 days to prepare a sample. After the surface of the glass plate was washed with water and dried, the surface of the glass plate was irradiated with a high-intensity lamp in a dark room and observed for cloudiness (n: 3). The corrosion evaluation of the glass plate was performed according to the following criteria. And A is judged to be qualified.

A: there was no blurring.

B: partially obscured.

C: blurred.

[ Table 1]

The evaluation results of examples 1 to 4 and comparative examples 1 to 2 are shown in Table 1. The glass lining paper of examples 1 to 4 was excellent in corrosion of glass plates. On the other hand, the glass lining paper of comparative examples 1 to 2 had poor corrosion to the glass plate.