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 a polyvinyl alcohol resin having a saponification degree of 70 mol% or more and 89 mol% or less.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 a polyvinyl alcohol resin having a saponification degree of 70 mol % or more and 89 mol % or less.

[0007] Polyvinyl alcohol resins with a saponification degree within the above range are more easily soluble in water than polyvinyl alcohol resins with a saponification degree of more than 89 mol percent. Therefore, during the process of producing recycled paper from the separator, the primer layer is more easily dissolved in water. In other words, the primer layer and release layer are more easily detached from the substrate. Therefore, the release layer of the separator (1) above is more easily detached from the substrate when recycled. The separator (1) above 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 polyvinyl alcohol resin may have a degree of saponification of 70 mol % or more and 87 mol % or less.

[0009] Polyvinyl alcohol resins having a degree of saponification within the above range are more easily soluble in water than polyvinyl alcohols having a degree of saponification of more than 87 mole percent.

[0010] (3) In the separator of (1) or (2), the polyvinyl alcohol resin may have a degree of saponification of 80 mol % or more and 84 mol % or less.

[0011] In the separator (3) above, the release layer is likely to come off from the substrate when recycled.

[0012] (4) In the separator of (1) or (2), the polyvinyl alcohol resin may have a degree of saponification of 70 mol % or more and 74 mol % or less.

[0013] In the separator (4) above, the release layer is likely to come off from the substrate when recycled.

[0014] (5) In the separator according to any one of (1) to (4), the primer layer may contain an antistatic agent.

[0015] The separator (5) above is less likely to become statically charged.

[0016] (6) In the separator of (5) above, the content of the antistatic agent in the primer layer may be 0.55% by mass or more.

[0017] The separator (6) is even less likely to be charged with static electricity.

[0018] (7) In the separator according to any one of (1) to (6), the release layer may contain a silicone-based resin.

[0019] The separator (7) above can have a release layer containing a silicone resin, since the release layer is easily detached from the substrate when recycled.

[0020] (8) In any of the separators (1) to (7) above, the substrate may be paper, resin, or a composite material of paper and resin.

[0021] Paper, resin, or composite materials are suitable for the substrate.

[0022] (9) In the separator of (8), the substrate may be paper, which may be wood-free paper, recycled paper, one-side glazed paper, greaseproof paper, coated paper, art paper, kraft paper, glassine paper, or cass-coated paper.

[0023] The above paper is suitable as the substrate.

[0024] (10) In the separator of (8), the substrate may be a resin, such as a polyester resin, a polyimide resin, a polypropylene resin, a polyamide resin, a polycarbonate resin, a polyacetate resin, a polyethylene resin, or a polyphenylene sulfide resin.

[0025] The above resins are suitable for the substrate.

[0026] (11) A separator according to one embodiment of the present invention includes a substrate, a primer layer, and a release layer, in this order. The substrate is paper. In a release test in which tape is attached to the surface 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 amount of the release layer remaining after the release test to the amount of the release layer coated before the release test is 15.00% or less.

[0027] In the separator of (11), the release layer is easily detached from the substrate when recycled. The ratio may be 13.00% or less or 12.00% or less.

[0028] (12) A separator according to one embodiment of the present invention includes a substrate, a primer layer, and a release layer, in this order. The substrate is made of resin. In a release test in which the release layer is immersed in room temperature water for 5 minutes without tape attached thereto, the ratio of the amount of the release layer remaining after the release test to the amount of the release layer coated before the release test is 1.00% or less.

[0029] In the separator of (12), the release layer is easily detached from the substrate when recycled. The ratio may be 0.75% or less, or 0.50% or less. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a cross-sectional view showing an outline of a separator according to an embodiment. [Figure 2] FIG. 2 is a plan view showing the state of ink printed on recycled paper sample No. 31. [Figure 3] FIG. 3 is a plan view showing the state of ink printed on recycled paper sample No. 301. DETAILED DESCRIPTION OF THE INVENTION

[0031] Embodiments of the separator of the present invention will be described with reference to the drawings. The same reference numerals in the drawings indicate the same or equivalent parts. The dimensions of the components shown in each drawing 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 all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0032] [Embodiment] <Separator> A separator 1 according to an embodiment will be described with reference to Figure 1. The separator 1 comprises a substrate 2, a primer layer 3, and a release layer 4, in this order. "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 a polyvinyl alcohol (PVA) resin that satisfies a specific degree of saponification.

[0033] ≪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 face in opposite directions along the thickness of the substrate 2. The substrate 2 is formed of paper, resin, or a composite material of paper and resin. The type of paper is not particularly limited. Known types of 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 type of resin is not particularly limited. Known types of resin can be used. Examples of the resin include polyester resin, polyimide resin, polypropylene resin, polyamide resin, polycarbonate resin, polyacetate resin, polyethylene resin, and polyphenylene sulfide resin. An example of a polyester resin is polyethylene terephthalate (PET) resin. The paper that forms the composite material is the paper described above, and the resin that forms the composite material is the resin described above. The thickness of the substrate 2 is not particularly limited.

[0034] <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.

[0035] 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.

[0036] The saponification degree of the PVA resin contained in the primer layer 3 is 70 mol% or more and 89 mol% or less. Hereinafter, in this specification, a PVA resin having a saponification degree of 70 mol% or more and 89 mol% or less may be referred to as a specific PVA resin. The specific PVA resin is more soluble in water than a PVA resin having a saponification degree of more than 89 mol%. Therefore, during the process of producing recycled paper from the separator 1, the primer layer 3 is more soluble in water. That is, 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 with a low content of the material forming the release layer 4 described below or recycled paper that does not contain the material forming the release layer 4. The saponification degree may be 70 mol% or more and 87 mol% or less. The saponification degree of the PVA resin contained in the primer layer 3 may be 70 mol% or more and 74 mol% or less, or 80 mol% or more and 84 mol% or less. The degree of saponification can be determined in accordance with JIS K 6726-1994.

[0037] The primer layer 3 may be formed substantially only from the specific PVA resin. "Formed substantially only from the specific PVA resin" means that, except for impurities, the primer layer 3 does not intentionally contain any additives other than the specific PVA resin. When the primer layer 3 is formed substantially only from the specific PVA resin, 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 the specific PVA resin, as needed. The additives may be at least one selected from the group consisting of, for example, a water-soluble resin containing starch, an antifoaming agent, an antiseptic, a filler, a crosslinking agent, and an antistatic agent. The total content of the additives in the primer layer 3 may be, for example, 2.0% by mass or less, 1.0% by mass or less, 0.5% by mass or less, or 0.1% by mass or less. When the primer layer 3 contains an antistatic agent, the content of the antistatic agent in the primer layer 3 is, for example, 0.55% by mass or more. In this case, the separator 1 is even less likely to be charged with static electricity. The content of the antistatic agent in the primer layer 3 is, for example, 2.0% by mass or less. The content of the antistatic agent in the primer layer 3 may be, for example, 0.60% by mass or more and 1.90% by mass or less, or 0.65% by mass or more and 1.80% by mass or less. The antistatic agent includes, for example, a polythiophene-based conductive polymer. The polythiophene-based conductive polymer is, for example, a composite of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid. The content of the specific PVA resin in the primer layer 3 may be, for example, 98.0% by mass or more, 99.0% by mass or more, 99.5% by mass or more, or 99.9% by mass or more. The total content of additives in the primer layer 3, the content of the antistatic agent in the primer layer 3, and the content of the specific PVA resin in the primer layer 3 are expressed as percentages relative to the mass of the primer layer 3 being 100% by mass.

[0038] The coating weight of the primer layer 3 can be selected appropriately depending on whether the substrate 2 is paper or resin. The surface of a resin substrate 2 is smoother than the surface of a paper substrate 2. Therefore, the coating weight of the primer layer 3 can be made smaller for a resin substrate 2 than for a paper substrate. When the substrate 2 is paper, the coating weight of the primer layer 3 can be, 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. When the substrate 2 is paper, 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 thickness is above this, the thickness of the primer layer 3 can be sufficiently ensured and coating can be performed without causing unevenness on the first surface 31. When the substrate 2 is made of resin, the coating amount of the primer layer 3 is, for example, 0.1 g / m 2 When the substrate 2 is made of resin, the coating amount of the primer layer 3 is, for example, 0.3 g / m 2 When the substrate 2 is made of paper or resin, if the coating amount of the primer layer 3 satisfies the above range, the release layer 4 is less likely to remain on the substrate 2 during recycling.

[0039] ≪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.

[0040] 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.

[0041] When the substrate 2 is paper, the release layer 4 is 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 even 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. When 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. When the substrate 2 is made of resin, the release layer 4 often does not contain an organic solvent, but may contain a very small amount of organic solvent. When the substrate 2 is made of resin, 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 in 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.

[0042] [Test Example 1: Paper substrate] In Test Example 1, the difference in ease of detachment of the release layer due to the difference in the degree of saponification of the PVA resin forming the primer layer was investigated.

[0043] <Samples No. 1 to No. 3, Sample No. 101, and Sample No. 102> 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.

[0044] The substrate used was a commonly used glassine paper.

[0045] The primer layer was formed by applying to the substrate a coating liquid containing, as a main component, a PVA resin whose degree of saponification was within the range shown in Table 1. The primer layer was formed substantially only from PVA resin. The degree of saponification of the PVA resin forming the primer layer was within the range shown in Table 1. In this example, the coating amount of the primer layer was 0.5 g / m 2 , 0.9g / m 2 , 1.4g / m 2 , or 2.4 g / m 2 It was.

[0046] 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 3. The release layer did not contain any organic solvents.

[0047] [Table 1]

[0048] <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 (25°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 2. In Table 2, "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.

[0049] The samples from which the release layer had been removed were dried. The amount of remaining release layer on the dried samples was measured by X-ray fluorescence analysis. The results are shown in Table 3.

[0050] 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 4.

[0051] [Table 2]

[0052] [Table 3]

[0053] [Table 4]

[0054] As shown in Table 2, in Samples No. 1 to No. 3, the release layer detached at each primer layer coating weight. On the other hand, in Samples No. 101 and No. 102, 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.

[0055] As shown in Table 3, for Samples No. 1 to No. 3, the residual amount of the release layer was 0.110 g / m for each primer layer coating amount. 2 It was as follows.

[0056] As shown in Table 4, for samples No. 1 to No. 3, at 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 15.00% or less, and even 12.00% or less.

[0057] Table 4 shows the following general trends. (1) 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. (2) As the degree of saponification of the PVA resin contained in the primer layer decreases, the ratio of the residual amount of the release layer to the coating amount decreases. PVA resins with low degrees of saponification contained in the primer layer are easily dissolved in water. Therefore, when the separator is immersed in water, the PVA resin dissolves in the water, causing the primer layer to separate from the substrate. At this time, as the primer layer separates from the substrate, the release layer provided on the primer layer (specifically, on the first surface 31 in Figure 1) also separates from the substrate. For this reason, it is presumed that the amount of the release layer, i.e., the silicone resin, remaining on the substrate is reduced.

[0058] [Test Example 2: Resin substrate] In Test Example 2, similarly to Test Example 1, the difference in ease of detachment of the release layer due to the difference in the degree of saponification of the PVA resin forming the primer layer was investigated.

[0059] <Samples No. 21 to No. 23, Sample No. 201, and Sample No. 202> The separators of Samples No. 21 to No. 23, Sample No. 201, and Sample No. 202 differ from Samples No. 1 to No. 3, Sample No. 101, and Sample No. 102 in the following respects. (1) The substrate was a film made of PET resin. (2) The coating weight of the primer layer is 0.3 g / m 2 It was.

[0060] <Desorption test> The ease of detachment of the release layer for each sample was evaluated by the following detachment test. This detachment test differed from Test Example 1 in that tape was not applied to the release layer and that some samples were immersed in water for a longer period of time. In this example, each sample was immersed in room-temperature water for 5 minutes or 30 minutes without tape applied to the release layer. Each sample was then removed from the water to check for detachment of the release layer. The results are shown in Table 5. In Table 5, "A" indicates that the release layer spontaneously detached from the substrate in water or spontaneously detached from the substrate simply by removing the release layer from the water. "B" indicates that at least a portion of the release layer remained attached to the substrate and did not detach from the substrate.

[0061] As in Test Example 1, the residual amount of the release layer was measured by X-ray fluorescence analysis. For Samples No. 201 and No. 202, only the residual amount was measured when the immersion time was 30 minutes. The results are shown in Table 6. Also, as in Test Example 1, 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 determined. The results are shown in Table 7.

[0062] [Table 5]

[0063] [Table 6]

[0064] [Table 7]

[0065] As shown in Table 5, the release layer of Samples No. 21 to No. 23 was detached when the immersion time was 5 minutes. On the other hand, the release layer of Samples No. 201 and No. 202 was not detached when the immersion time was 5 minutes. Furthermore, the release layer of Sample No. 201 was not detached even when the immersion time was 30 minutes. However, the release layer of Sample No. 202 was detached when the immersion time was 30 minutes. It was found that Samples No. 21 to No. 23 were able to detach the release layer in a shorter time than Samples No. 201 and No. 202.

[0066] As shown in Table 6, in Samples No. 21 to No. 23, the residual amount of the release layer was 0.010 g / m 2 It was as follows.

[0067] As shown in Table 7, in Samples No. 21 to No. 23, the ratio of the residual amount of the release layer to the coating amount of the release layer was 1.00% or less, and even 0.50% or less.

[0068] [Test Example 3: Properties of recycled paper] In Test Example 3, recycled paper was produced from the separator, and ink was applied to the recycled paper to examine the difference in the degree of ink adhesion.

[0069] <Sample No. 31, Sample No. 301> The recycled paper of sample No. 31 has a primer layer coating weight of 1.4 g / m2, which is the same as the separator of sample No. 2. 2The recycled paper of sample No. 301 was manufactured using a separator with a primer layer coating weight of 1.4 g / m2, which is the same as that of sample No. 101. 2 The separators were manufactured using a separator of the same type. First, the separators of each sample were disintegrated using a disintegrator. The disintegrator used was a pulper manufactured by Kumagai Riki Kogyo Co., Ltd. The capacity of the pulper was 2 L (liters). Next, recycled paper sheets were manufactured from the disintegrated separators using a small sheet machine.

[0070] <Evaluation of ink adhesion> Ink was printed onto each sample of recycled paper using a coating bar. The ink used was a water-based indigo ink from the water-based ink series manufactured by Fuji Ink Mfg. Co., Ltd. Plan views showing the printed surface of each sample are shown in Figures 2 and 3. In each figure, the granular areas represent areas X where no ink is attached, and the remaining areas represent areas Y where ink is attached.

[0071] A comparison of Figures 2 and 3 reveals the following: As shown in Figure 2, the recycled paper of Sample No. 31 has very few areas X where ink is not applied, and the size of the areas X is also very small. As shown in Figure 3, the recycled paper of Sample No. 301 has a very large number of areas X where ink is not applied, and the size of the areas X is relatively large. For Sample No. 31, the recycled paper has areas Y where ink is applied over virtually the entire area. Compared to Sample No. 31, the recycled paper of Sample No. 301 has less areas Y where ink is applied over the entire area. The ratio of the total area of ​​the areas X to the total area of ​​each sample was calculated. That is, this ratio was calculated by multiplying (total area of ​​areas X / total area) by 100. For Sample No. 31, this ratio was approximately 0.011%. For Sample No. 301, this ratio was approximately 0.848%.

[0072] Region X in each sample of recycled paper was examined using X-ray fluorescence analysis, and it was found that region X was silicone resin.

[0073] The above results were obtained because the release layer, i.e., the silicone resin, of Sample No. 31 was detached from the substrate by the defibration device, while the release layer, i.e., the silicone resin, of Sample No. 301 was not detached from the substrate by the defibration device. As described above, the recycled paper of Sample No. 31 was produced using the separator of Sample No. 2, in which the release layer was detached from the substrate by peeling off the tape in Test Example 1. In Test Example 1, the separators of Sample No. 1 and Sample No. 3 also detached the release layer from the substrate by peeling off the tape, similar to Sample No. 2. From these results, it is considered that even when separators of Sample No. 1 and Sample No. 3 are used, the release layer, i.e., the silicone resin, is detached from the substrate by the defibration device, similar to Sample No. 31. In other words, it can be said that the separators of Sample No. 1 to Sample No. 3, in which the release layer was detached from the substrate by peeling off the tape in Test Example 1, have a release layer that is easily detached from the substrate when recycled. In Test Example 2, Samples No. 21 to No. 23, in which the release layer was detached from the substrate without using tape, naturally have a tendency to have the release layer detached from the substrate easily during recycling.

[0074] [Test Example 4: Resin substrate] In Test Example 4, the ease of separation of the release layer due to the inclusion of an antistatic agent in the primer layer was examined.

[0075] <Samples No. 41 to No. 46> Two types of separators were manufactured using different types of silicone resin for the release layer for sample No. 41. The separator for sample No. 41 differs from sample No. 2 mainly in that the coating amount of the release layer is smaller. One type of laminate was manufactured for each of Samples No. 42 to No. 44. The laminate for each sample consisted of a substrate and a primer layer, and did not have a release layer. The laminates for Samples No. 42 to No. 44 differed from Sample No. 2 mainly in that the primer layer contained an antistatic agent and that they did not have a release layer. Two types of separators were manufactured using different types of silicone resin for the release layer: Sample No. 45 and Sample No. 46. The separators for Sample No. 45 and Sample No. 46 differ from Sample No. 2 mainly in that the primer layer contains an antistatic agent and the coating weight of the release layer is small. The antistatic agent for samples No. 42 to No. 46 was primarily composed of a polythiophene-based conductive polymer. Specifically, the antistatic agent for samples No. 42 to No. 46 was the conductive paint Denatron BLC-N1-3 manufactured by Nagase ChemteX Corporation.

[0076] The primer layers of Samples No. 42 to No. 46 were formed by applying a coating liquid containing a PVA resin with a saponification degree of 80.0 mol% to 84.0 mol% and an antistatic agent to the substrate. The mass ratio of the PVA resin to the antistatic agent, where the total mass of the PVA resin and the antistatic agent in the coating liquid is taken as 10, is shown in Table 8. The coating amount (g / m) of the primer layer for each sample was 2 ), the content (mass%) of the antistatic agent in the primer layer of each sample, and the coating weight (g / m) of the release layer in Sample No. 41, Sample No. 45, and Sample No. 46. 2 ) are shown in Table 8.

[0077] [Table 8]

[0078] <Surface resistivity> The surface resistivity (Ω / □: ohms per square) of the primer layer and the surface resistivity (Ω / □) of the release layer of each sample were measured. The surface resistivity of the primer layer was measured before the release layer was applied. A surface resistivity meter ST-4 manufactured by Simco Japan Co., Ltd. was used for the measurement. The unit "Ω / □" is the measurement value obtained in a measurement area of ​​50 mm x 50 mm, expressed as "1 cm 2 The surface resistivity was measured twice and the average values ​​are shown in Table 9.

[0079] [Table 9]

[0080] <Desorption test> The ease of detachment of the release layer in Samples No. 41, 45, and 46 was evaluated by conducting a detachment test similar to that in Test Example 2. The results are shown in Table 10. "A" in Table 10 is an evaluation result based on the same criteria as in Test Example 2.

[0081] As in Test Example 2, the residual amounts of the release layers in Samples No. 41, 45, and 46 were measured by fluorescent X-ray analysis. The results are shown in Table 11.

[0082] [Table 10]

[0083] [Table 11]

[0084] As shown in Table 9, the surface resistivity of the primer layer of Sample No. 45 and Sample No. 46 was smaller than the surface resistivity of the primer layer of Sample No. 41 to Sample No. 44. In other words, it was found that Sample No. 45 and Sample No. 46 were even less susceptible to static electricity than Sample No. 41 to Sample No. 44.

[0085] As shown in Table 10, the release layer was removed from Samples No. 41, 45, and 46. It was found that even when the primer layer contained a water-insoluble antistatic agent, the release layer could be removed in a short time, just as when the primer layer did not contain an antistatic agent. From these results, it is believed that the release layer could also be removed in a short time from Samples No. 42 to No. 44.

[0086] As shown in Table 11, in Samples No. 41, No. 45, and No. 46, the residual amount of the release layer was 0.010 g / m 2 The results were as follows: Even if the primer layer contains a water-insoluble antistatic agent, it was found that the amount of residual release layer can be reduced, just as in the case where the primer layer does not contain an antistatic agent. From these results, it is believed that the amount of residual release layer can also be reduced in Samples No. 42 to No. 44.

[0087] Furthermore, even if the primer layer contains at least one additive selected from the group consisting of a water-soluble resin containing starch, an antifoaming agent, a preservative, a filler, and a crosslinking agent, it is expected that the release layer can be removed in a short period of time and the amount of residual release layer can be reduced. [Explanation of symbols]

[0088] 1 Separator 2 Base material 21 Page 1 22 Side 2 3 Primer layer 31 Page 1 32 Side 2 4 Release layer X, Y area

Claims

1. A substrate, a primer layer, and a release layer are provided in this order, the primer layer contains a polyvinyl alcohol resin having a saponification degree of 70 mol % or more and 89 mol % or less; Separator.

2. 2. The separator according to claim 1, wherein the polyvinyl alcohol resin has a degree of saponification of 70 mol % or more and 87 mol % or less.

3. The separator according to claim 2, wherein the polyvinyl alcohol resin has a degree of saponification of 80 mol % or more and 84 mol % or less.

4. The separator according to claim 2, wherein the polyvinyl alcohol resin has a degree of saponification of 70 mol % or more and 74 mol % or less.

5. The separator according to claim 1 or 2, wherein the primer layer contains an antistatic agent.

6. The separator according to claim 5 , wherein the content of the antistatic agent in the primer layer is 0.55% by mass or more.

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

8. The separator according to claim 1 or 2, wherein the substrate is paper, resin, or a composite material of paper and resin.

9. the substrate is paper, The separator according to claim 8 , 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.

10. the substrate is a resin, 9. The separator according to claim 8, wherein the resin is a polyester resin, a polyimide resin, a polypropylene resin, a polyamide resin, a polycarbonate resin, a polyacetate resin, a polyethylene resin, or a polyphenylene sulfide resin.

11. A substrate, a primer layer, and a release layer are provided in this order, the substrate is paper, In a removal test in which a tape is attached to the 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 15.00% or less. Separator.

12. A substrate, a primer layer, and a release layer are provided in this order, the substrate is a resin, In a release test in which the release layer is immersed in water at room temperature for 5 minutes without tape attached thereto, the ratio of the remaining amount of the release layer after the release test to the coating amount of the release layer before the release test is 1.00% or less. Separator.

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