Separator

Abstract

To provide a separator enabling easy detachment of a release layer from a base material containing paper at the time of recycling.SOLUTION: A separator includes, in this order, a base material, a primer layer, and a release layer, wherein the base material includes paper, and the primer layer includes a water-soluble polyester resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a method for recovering a release film, which comprises a base film and a release layer, and involves separating and removing the release layer from the base film, recovering only the base film. The base film is made of resin. A readily soluble resin layer is provided between the base film and the release layer. When the release film is immersed in a solvent capable of dissolving the readily soluble resin layer, the readily soluble resin layer dissolves in the solvent, and the release layer is separated from the base film. The recovered base film is recycled. The release film is called a separator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-265665 Summary of the Invention [Problem to be solved by the invention]

[0004] Even in separators in which a release layer is provided on a substrate containing paper, it is desirable to recover the substrate from the separator after use and recycle the substrate. In substrates containing paper, a filler layer is provided between the substrate and the release layer to prevent the material forming the release layer from seeping into the substrate. The technology of Patent Document 1 does not consider a filler layer suitable for detaching the release layer from a substrate containing paper.

[0005] One object of the present invention is to provide a separator in which the release layer is easily detached from the substrate containing paper when recycled. [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 substrate includes paper. The primer layer includes a water-soluble polyester resin.

[0007] Water-soluble polyester resins have high solubility in water. Because a primer layer containing a water-soluble polyester resin is provided between the substrate and the release layer, the primer layer dissolves in water when the separator is immersed in water. The dissolution of the primer layer in water facilitates the release layer to detach from the substrate. Therefore, with the separator (1) above, the substrate can be easily recovered from the separator.

[0008] A primer layer containing a water-soluble polyester resin can prevent the material forming the release layer from seeping into a substrate, including paper. Furthermore, a primer layer containing a water-soluble polyester resin can detach the release layer from the substrate by dissolving in water. Therefore, with the separator (1) above, the material forming the release layer is less likely to be mixed into the substrate recovered from the separator. Therefore, the separator (1) above is suitable for producing recycled paper with little mixed-in material forming the release layer. Recycled paper with little mixed-in material forming the release layer is less likely to experience paint cissing. Paint cissing is an area where the coating film is locally thin or where no coating film is formed when recycled paper is printed.

[0009] (2) In the separator of (1) above, the release layer may contain a silicone-based resin.

[0010] Silicone-based resins are suitable for the release layer.

[0011] (3) In the separator of (1) or (2) above, in a removal test in which tape is attached to the surface of the release layer opposite the primer layer and the separator is immersed in water at 40°C for 5 minutes, and then the tape is peeled off, the ratio of the amount of the release layer remaining after the removal test to the amount of coating of the release layer before the removal test is 1.00% or less.

[0012] The separator (3) above is less likely to contain the material that forms the release layer in the substrate recovered from the separator, and is therefore suitable for producing recycled paper with little contamination by the material that forms the release layer. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing an outline of a separator according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Specific examples of the separator of the present invention will be described with reference to the drawings. 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 and proportions. 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.

[0015] [Embodiment] <Separator> As shown in Figure 1, separator 1 comprises substrate 2, primer layer 3, and release layer 4 in this order. "Having substrate 2, primer layer 3, and release layer 4 in this order" means that substrate 2, primer layer 3, and release layer 4 are laminated in this order, and no other layer is disposed between substrate 2 and primer layer 3, or between primer layer 3 and release layer 4. One of the features of separator 1 is that primer layer 3 contains a water-soluble polyester resin.

[0016] ≪Base material≫ The substrate 2 includes paper. The substrate 2 is formed in a sheet shape. 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 substrate 2 may be a composite material of paper and resin. The composite material may be a laminate of paper and a resin film, or paper coated with resin. The resin may be, for example, polyethylene.

[0017] 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 thickness of the substrate 2 is not particularly limited and can be any known thickness.

[0018] <Primer layer> The primer layer 3 functions to facilitate detachment of the release layer 4 from the substrate 2. The primer layer 3 also functions as a sealing layer that prevents the material forming the release layer 4, which will be described later, from penetrating into the substrate 2.

[0019] 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 means that the primer layer 3 is in direct contact with the first surface 21. In other words, no layer other than the substrate 2 and the primer layer 3 is provided between the substrate 2 and the primer layer 3. The primer layer 3 is provided over the entire surface of the first surface 21.

[0020] The primer layer 3 has a first surface 31 and a second surface 32. The first surface 31 and the second surface 32 are surfaces that face in opposite directions along the thickness of the primer layer 3. The first surface 31 is a surface that faces in the opposite direction from the surface that faces the substrate 2. The second surface 32 is a surface that faces the substrate 2 and is in direct contact with the substrate 2. The primer layer 3 has a single-layer structure.

[0021] The primer layer 3 contains a water-soluble polyester resin. Water-soluble polyester resins have high solubility in water. Because the primer layer 3 containing the water-soluble polyester resin is provided between the substrate 2 and the release layer 4, the primer layer 3 dissolves in water when the separator 1 is immersed in water. The dissolution of the primer layer 3 in water makes it easier for the release layer 4 to detach from the substrate 2.

[0022] The primer layer 3 may be formed substantially solely from a water-soluble polyester resin. "Formed substantially solely from a water-soluble polyester resin" means that, except for impurities, no additives other than the water-soluble polyester resin are intentionally included. When the primer layer 3 is formed substantially solely from a water-soluble polyester 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 water-soluble polyester resin, as needed. Examples of 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 the water-soluble polyester resin in the primer layer 3 may be, for example, 90.0% by mass or more, 99.5% by mass or more, or 99.9% by mass or more. The content of the additives or water-soluble polyester resin in the primer layer 3 is the ratio relative to the mass of the primer layer 3 being 100% by mass.

[0023] The coating amount of the primer layer 3 is, for example, 0.3 g / m 2 The coating weight of the primer layer is 0.3 g / m 2 With the above, 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 through the irregularities of the primer layer 3. 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 amount is above this, the thickness of the primer layer 3 can be sufficiently ensured while coating can be performed without causing unevenness on the first surface 31. When 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.

[0024] ≪Release layer≫ The release layer 4 is provided on the first surface 31 of the primer layer 3. 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, no layer other than the primer layer 3 and the release layer 4 is provided 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.

[0025] 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 perspective of the releasability of the separator 1, the release layer 4 may be formed from a silicone-based resin.

[0026] The release layer 4 of this example 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 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 when the release layer 4 is formed on the first surface 31 during the manufacturing process of the separator 1, the coating liquid does not substantially contain an organic solvent that would enhance 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 good 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.

[0027] [Test example] In the test example, the ease of detachment of the release layer from the substrate in a separator having a primer layer containing a water-soluble polyester resin was examined.

[0028] <Sample> Samples No. 1 to No. 4 and Samples No. 11 to No. 14 are separators having a primer layer provided on the first surface of the substrate and a release layer provided on the primer layer. The same substrate was used for Samples No. 1 to No. 4 and Samples No. 11 to No. 14. The substrate was commonly used glassine paper.

[0029] In Samples No. 1 to No. 4, a primer layer was formed by coating a water-soluble polyester resin on the first surface of the substrate. In Samples No. 1 to No. 4, the primer layer 3 was formed essentially only from water-soluble polyester resin. Samples No. 1 to No. 4 differed in the coating weight of the primer layer. The coating weight of the primer layer for each sample is shown in Table 1. The water-soluble polyester resin used in Samples No. 1 to No. 4 was PLASCOAT Z-221 manufactured by GOO Chemical Industry Co., Ltd. In Samples No. 1 to No. 4, the water contact angle of the primer layer was 40°, the softening point was 135 to 140°C, and the pencil hardness was 2H.

[0030] For Samples No. 11 to No. 14, a primer layer was formed by coating the first surface of the substrate with polyvinyl alcohol (PVA) resin. For Samples No. 11 to No. 14, the primer layer was formed essentially only with polyvinyl alcohol resin. "Formed essentially only with polyvinyl alcohol resin" means that, with the exception of impurities, no additives other than polyvinyl alcohol resin are intentionally included. Samples No. 11 to No. 14 differ in the coating weight of the primer layer. The coating weight for each sample is shown in Table 1. The polyvinyl alcohol resin used for Samples No. 11 to No. 14 was fully saponified polyvinyl alcohol manufactured by Nippon Vaccination & Poval Co., Ltd.

[0031] The release layer of each sample used a release agent whose main component was silicone resin. The release agent did not contain any organic solvent. In other words, the release layer did not contain any organic solvent. The coating weight of the release layer for each sample is shown in Table 1.

[0032] <Release layer detachment test> The ease of detachment of the release layer from the substrate for each sample was evaluated by conducting a release layer detachment test. The release layer detachment test was performed using the following procedure. First, tape was attached 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 40°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 to check whether the release layer had detached from the substrate. The results are shown in Table 1. "A" in Table 1 indicates a state in which the release layer was attached to the tape and peeled off from the substrate. "B" in Table 1 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.

[0033] [Table 1]

[0034] As shown in Table 1, in samples No. 1 to No. 4, in which the primer layer was made of a water-soluble polyester resin, the release layer detached from the substrate regardless of the coating amount of the primer layer. In samples No. 11 to No. 14, in which the primer layer was made of a polyvinyl alcohol resin, the release layer did not detach from the substrate. These results demonstrate that the primer layer made of a water-soluble polyester resin is easily dissolved in water, and therefore the release layer easily detaches from the paper substrate. Here, as mentioned above, the release layer is formed from a silicone resin, which is a release agent. Therefore, in a separator, detachment of the release layer from the substrate is synonymous with detachment of the silicone resin.

[0035] <Residual amount of release layer> The amount of residual release layer was measured for the substrates of Samples No. 1 to No. 4 from which the release layer had been removed. After the recovered substrates were dried, the amount of residual release layer on the first surface of the substrate was measured using X-ray fluorescence analysis. The results are shown in Table 2. Furthermore, for each sample whose residual amount was measured, the ratio of the amount of residual release layer after the removal test to the amount of coating of the release layer before the removal test was calculated. This ratio was calculated by (residual amount / coating amount) x 100. The results are shown in Table 2.

[0036] [Table 2]

[0037] As shown in Table 2, in the substrates of Samples No. 1 to No. 4 from which the release layer had been removed, the ratio of the amount of residual release layer to the coating amount of the release layer was 1.00% or less. Substrates with a small amount of residual release layer are suitable for producing recycled paper. [Explanation of symbols]

[0038] 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 substrate comprises paper; The primer layer contains a water-soluble polyester resin. Separator.

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

3. 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 the primer layer, the surface is immersed in water at 40°C for 5 minutes, and then the tape is peeled off, the ratio of the amount of the release layer remaining after the removal test to the amount of the release layer coated before the removal test is 1.00% or less.

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