Separator

Abstract

To provide a separator that allows easy detachment of a release layer from a base material at the time of recycling.SOLUTION: A separator includes, in this order, a base material, a primer layer, and a release layer, wherein the primer layer contains carboxymethyl cellulose.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a separator. [Background technology]

[0002] Patent Document 1 discloses a separator that is a release paper including a paper substrate, a filler layer provided on the surface of the substrate, and a release layer provided on the surface of the filler layer. The release layer is also called a release layer. The filler layer prevents the material forming the release layer from seeping into the substrate. The filler layer is made of polyvinyl alcohol (PVA) resin. The release layer is made of a silicone-based resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-170097 Summary of the Invention [Problem to be solved by the invention]

[0004] Recycling separators is desirable from the perspective of environmental protection and resource conservation. In the process of producing recycled paper from separators, it is necessary to remove the filler layer and release layer from the substrate. The reason for this is as follows: If the filler layer and release layer are not properly removed from the substrate, recycled paper containing silicone-based resins that form the release layer is produced. When this recycled paper is printed, paint cissing can occur. Paint cissing refers to areas where paint does not adhere to the silicone-based resin-containing areas of the recycled paper, resulting in locally thin coatings or areas where no coating is formed.

[0005] An object of the present invention is to provide a separator in which the release layer is easily detached from the substrate during recycling. [Means for solving the problem]

[0006] (1) A separator according to one aspect of the present invention includes a substrate, a primer layer, and a release layer, in this order. The primer layer contains carboxymethyl cellulose.

[0007] Carboxymethyl cellulose is easily soluble in water. Therefore, during the process of producing recycled paper from the separator, the primer layer is easily dissolved in water. In other words, the primer layer and release layer are easily detached from the substrate. Therefore, when the separator (1) is recycled, the release layer is easily detached from the substrate. The separator (1) is suitable for producing recycled paper with a low content of the material that forms the release layer.

[0008] (2) In the separator of (1) above, the release layer may contain a silicone-based resin.

[0009] The separator (2) above can have a release layer containing a silicone resin, since the release layer is easily detached from the substrate when recycled.

[0010] (3) In the separator of (1) or (2), the substrate may be paper.

[0011] Paper is a preferred substrate.

[0012] (4) In the separator of (3) above, the paper may be high-quality paper, recycled paper, one-side glazed paper, greaseproof paper, coated paper, art paper, kraft paper, glassine paper, or cass-coated paper.

[0013] The above-mentioned paper is suitable as the substrate.

[0014] (5) In any of the separators (1) to (4) above, the substrate may be paper, and in a detachment test in which tape is attached to the side of the release layer opposite the primer layer, the layer is immersed in water at room temperature for 5 minutes, and then the tape is peeled off, the ratio of the residual amount of the release layer after the detachment test to the coating amount of the release layer before the detachment test may be 5.00% or less.

[0015] In the separator of (5) above, the release layer is easily detached from the substrate when recycled. The ratio may be 4.00% or less, 3.00% or less, or 2.50% or less. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing an outline of a separator according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the separator of the present invention will be described with reference to Figure 1. The dimensions of the components shown in the drawings are expressed for the purpose of clarity of explanation and do not necessarily represent actual dimensions. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0018] [Embodiment] <Separator> The separator 1 of the embodiment comprises, in this order, a substrate 2, a primer layer 3, and a release layer 4. "Composed of the substrate 2, the primer layer 3, and the release layer 4" means that the substrate 2, the primer layer 3, and the release layer 4 are laminated in this order, and no other layer is disposed between the substrate 2 and the primer layer 3, or between the primer layer 3 and the release layer 4. One of the features of the separator 1 is that the primer layer 3 contains carboxymethyl cellulose (CMC).

[0019] ≪Base material≫ The substrate 2 is formed in a sheet shape. The substrate 2 has a first surface 21 and a second surface 22. The first surface 21 and the second surface 22 are surfaces facing in opposite directions along the thickness of the substrate 2. The substrate 2 is formed, for example, from paper. The type of paper is not particularly limited. Any known paper can be used. Examples of the paper include fine paper, recycled paper, single-side glazed paper, greaseproof paper, coated paper, art paper, kraft paper, glassine paper, and cass-coated paper. The thickness of the substrate 2 is not particularly limited.

[0020] <Primer layer> The primer layer 3 has the function of facilitating detachment of the release layer 4 from the substrate 2. When the substrate 2 is made of paper, the primer layer 3 also functions as a sealing layer that prevents the material forming the release layer 4 from penetrating into the substrate 2.

[0021] The primer layer 3 is provided on the first surface 21 of the substrate 2. The primer layer 3 is provided on the first surface 21 of the substrate 2 when the primer layer 3 is in direct contact with the first surface 21. In other words, the separator 1 does not have any other layers between the substrate 2 and the primer layer 3. The primer layer 3 is provided over the entire first surface 21. The primer layer 3 has a first surface 31 and a second surface 32. The first surface 31 and the second surface 32 face in opposite directions along the thickness of the primer layer 3. The first surface 31 faces in the opposite direction from the surface facing the substrate 2. The second surface 32 faces the substrate 2 and is in direct contact with the substrate 2. The primer layer 3 has a single-layer structure.

[0022] The primer layer 3 contains CMC. CMC is easily soluble in water. Therefore, during the process of producing recycled paper from the separator 1, the primer layer 3 is easily soluble in water. In other words, the primer layer 3 and the release layer 4 are easily detached from the substrate 2. Therefore, when the separator 1 is recycled, the release layer 4 is easily detached from the substrate 2. Such a separator 1 is suitable for producing recycled paper that contains a small amount of material that forms the release layer 4, or recycled paper that does not contain material that forms the release layer 4. The CMC contained in the primer layer 3 may be an alkali salt of CMC. The alkali salt of CMC is, for example, a sodium salt of CMC.

[0023] The primer layer 3 may be formed substantially only with CMC. "Formed substantially only with CMC" means that, except for impurities, no additives other than CMC are intentionally included. When the primer layer 3 is formed substantially only with CMC, the primer layer 3 is easily dissolved in water, and the release layer 4 is easily detached from the substrate 2. The primer layer 3 may contain additives in addition to CMC, as necessary. Examples of such additives include water-soluble resins containing starch, antifoaming agents, preservatives, fillers, crosslinking agents, and antistatic agents. The content of the additives in the primer layer 3 may be, for example, 1.0% by mass or less, 0.5% by mass or less, or 0.1% by mass or less. In other words, the content of CMC in the primer layer 3 may be, for example, 99.0% by mass or more, 99.5% by mass or more, or 99.9% by mass or more. The content of the additives or CMC in the primer layer 3 is a ratio based on the mass of the primer layer 3 being 100% by mass.

[0024] The higher the degree of etherification of CMC, the more easily it dissolves in water. Therefore, if the primer layer 3 contains CMC with a high degree of etherification, the release layer 4 is more likely to detach from the substrate 2 when the separator 1 is recycled. The lower the degree of etherification of CMC, the higher the viscosity tends to be, making it easier to apply to the substrate 2. Furthermore, the lower the degree of etherification of CMC, the better the adhesion to the substrate 2.

[0025] The coating amount of the primer layer 3 is, for example, 0.3 g / m 2 That's all. In this case, the primer layer 3 can be applied evenly. As a result, the first surface 31 of the primer layer 3 has reduced irregularities. Therefore, when the release layer 4 described below is applied onto the first surface 31 of the primer layer 3, the material forming the release layer 4 can be prevented from penetrating into the substrate 2 via the irregularities of the primer layer 3. Furthermore, the release layer 4 is less likely to remain on the substrate 2 when recycled. The coating amount of the primer layer 3 is 0.5 g / m 2 The coating amount of the primer layer 3 may be 0.5 g / m or more. 2 If the above conditions are met, the primer layer 3 can be applied without unevenness on the first surface 31 while ensuring a sufficient thickness.

[0026] ≪Release layer≫ The release layer 4 is provided on the first surface 31 of the primer layer 3, which is the surface opposite to the substrate 2. The release layer 4 is provided on the first surface 31 of the primer layer 3 means that the release layer 4 is in direct contact with the first surface 31. In other words, the separator 1 does not have any layer other than the primer layer 3 and the release layer 4 between the primer layer 3 and the release layer 4. The release layer 4 is provided on the entire surface of the first surface 31.

[0027] The material for forming the release layer 4 is not particularly limited, and known release agents can be used. Examples of materials for forming the release layer 4 include silicone-based resins, fluorine-based resins, alkyd resins, long-chain alkyl resins, and various waxes. If the release layer 4 is formed from these materials, the separator 1 can be easily peeled from an adherend (not shown). The adherend is an adhesive layer provided on an adhesive sheet (not shown). In particular, from the viewpoint of the releasability of the separator 1, the material for forming the release layer 4 is preferably a silicone-based resin.

[0028] The release layer 4 may be substantially free of organic solvents. Examples of organic solvents include toluene, hexane, cyclohexane, ethyl acetate, butyl acetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, and butanol. The release layer 4 being substantially free of organic solvents means that the release layer 4 contains an extremely small amount of organic solvent or 0 (zero) mass%. The content of the organic solvent in the release layer 4 is a ratio relative to the mass of the release layer 4, which is 100 mass%. The release layer 4 being substantially free of organic solvents means that, during the manufacturing process of the separator 1, when the release layer 4 is formed on the first surface 31, the coating liquid does not substantially contain an organic solvent for enhancing the fluidity of the coating liquid. Because the coating liquid is substantially free of organic solvents, the working environment during the manufacturing of the separator 1 is favorable and the health of the workers is less likely to be affected. If the release layer 4 is completely free of organic solvents, there is no need to use the primer layer 3 to prevent the organic solvent from penetrating into the substrate 2 during the manufacturing process. The release layer 4 often does not contain an organic solvent, but may contain a very small amount of organic solvent. The release layer 4 may be coated using an organic solvent. The organic solvent evaporates and disappears, but a very small amount of organic solvent may remain on the release layer 4. Even in this case, the amount of remaining organic solvent is so small that it has almost no impact on workers or the environment.

[0029] [Test example] In the test example, the difference in ease of detachment of the release layer in separators in which the primer layer was formed of CMC was investigated.

[0030] <Sample No. 1 to Sample No. 3> Each sample separator was manufactured by forming a primer layer on the first surface of the substrate and then forming a release layer on the first surface of the primer layer. For each sample, four types of separators were manufactured with different coating amounts of the primer layer.

[0031] The substrate used was a commonly used glassine paper.

[0032] The primer layer of each sample was formed by applying a coating liquid containing CMC as the main component to the substrate. The primer layer of each sample was formed using the following sodium salt of CMC. The primer layer of sample No. 1 was formed using Sunrose (registered trademark) APP-84 manufactured by Nippon Paper Industries Co., Ltd. The primer layer of sample No. 2 was formed using Sunrose (registered trademark) FT-3G manufactured by Nippon Paper Industries Co., Ltd. The primer layer of sample No. 3 was formed using SYL-1 manufactured by Kimika Co., Ltd. The primer layer of each sample was formed essentially using only CMC. The coating weight of the primer layer of each sample was the value shown in Table 1. In Table 1, "-" indicates that there was no sample with the corresponding coating weight.

[0033] The release layer was formed by applying a coating solution containing silicone resin as the main component to the primer layer. The coating solution did not contain any organic solvents. The coating weight of the release layer was the value shown in the top row of Table 2. The release layer did not contain any organic solvents.

[0034] <Sample No. 101> Sample No. 101 differs from Sample No. 1 and the like in that the primer layer is formed from a PVA resin having a degree of saponification of 98.0 mol% or more and 99.0 mol% or less, and the coating weight of the primer layer is the value shown in Table 1.

[0035] <Desorption test> The ease of detachment of the release layer of each sample was evaluated by the following detachment test. Tape was applied to the side of the release layer of each sample opposite the primer layer. Silicone adhesive tape (Sliontec (registered trademark) No. 626050, manufactured by Maxell Co., Ltd.) was used. Each sample with the tape attached was immersed in water at room temperature (23°C) and left to stand for 5 minutes. Then, each sample with the tape attached was removed from the water and the tape was peeled off. Whether or not the release layer had detached from the substrate was confirmed. The results are shown in Table 1. In Table 1, "A" indicates a state in which the release layer was attached to the tape and peeled off from the substrate. "B" indicates a state in which the tape did not peel off, or a state in which the tape peeled off but at least a portion of the release layer remained bonded to the substrate by the primer layer, making it impossible to detach the release layer from the substrate.

[0036] The sample from which the release layer had been removed was dried. After drying, the amount of remaining release layer on the sample was measured by X-ray fluorescence analysis. The results are shown in Table 2.

[0037] For the samples for which the residual amount was measured, the ratio of the residual amount of the release layer after the release test to the coating amount of the release layer before the release test was calculated. That is, this ratio was calculated by (residual amount / coating amount) x 100. The results are shown in Table 3.

[0038] [Table 1]

[0039] [Table 2]

[0040] [Table 3]

[0041] As shown in Table 1, in Samples No. 1 to No. 3, the release layer detached at each primer layer coating weight. On the other hand, in Sample No. 101, the release layer, i.e., the silicone resin, did not detach at each primer layer coating weight. Here, as described above, the release layer is formed from a silicone resin, which is a release agent. Therefore, detachment of the release layer from the substrate in the separator is synonymous with detachment of the silicone resin.

[0042] As shown in Table 2, for Samples No. 1 to No. 3, the residual amount of the release layer was 0.020 g / m for each coating amount of the primer layer. 2 As shown in Table 3, in Samples No. 1 to No. 3, for each coating amount of the primer layer, the ratio of the residual amount of the release layer to the coating amount of the release layer was 2.00% or less.

[0043] Table 3 shows the following general trends: The greater the coating weight of the primer layer, the smaller the ratio of the residual amount to the coating weight of the release layer. A primer layer with a larger coating weight reduces the surface irregularities. This is thought to be because a release layer is formed on top of the primer layer, making it difficult for the silicone resin contained in this release layer to penetrate into the substrate. [Explanation of symbols]

[0044] 1 Separator 2 Base material 21 Page 1 22 Side 2 3 Primer layer 31 Page 1 32 Side 2 4 Release layer

Claims

1. A substrate, a primer layer, and a release layer are provided in this order, The primer layer contains carboxymethyl cellulose. Separator.

2. The separator according to claim 1 , wherein the release layer comprises a silicone-based resin.

3. The separator according to claim 1 or 2, wherein the substrate is paper.

4. The separator according to claim 3 , wherein the paper is fine paper, recycled paper, one-side glazed paper, greaseproof paper, coated paper, art paper, kraft paper, glassine paper, or cass-coated paper.

5. the substrate is paper, 3. The separator according to claim 1, wherein in a removal test in which a tape is attached to a surface of the release layer opposite to the primer layer, the surface is immersed in water at room temperature for 5 minutes, and then the tape is peeled off, the ratio of the remaining amount of the release layer after the removal test to the coating amount of the release layer before the removal test is 5.00% or less.

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