JP7536629B2 - Release paper base paper, release paper, adhesive tape, and method for producing release paper base paper - Google Patents

Description

The present invention relates to release paper base paper, release paper, adhesive tape, and a method for producing release paper base paper.

In recent years, in release papers that have a release agent layer on the surface of a paper substrate, a filling layer or the like has been formed between the paper substrate and the release agent layer to minimize the penetration of the release agent into the paper substrate and to improve its releasability. The filling layer is provided for the purpose of preventing the release agent from penetrating into the paper substrate when it is applied and for the purpose of forming a release agent layer on the surface.

For example, Patent Document 1 discloses such release paper, which is made by providing a release agent layer on a base paper, and in which the base paper is made of glassine paper that has been press-smoothed to have a 10-point average roughness value of 10 μm or less as specified in JIS B 0601, and the release agent layer is coated with a solvent-free release agent.

Patent document 2 discloses a method for producing base paper for release paper in which a coating liquid is applied to the surface of the paper using a coating device directly connected to a multi-stage supercalender device.

Patent Document 3 also discloses a method for producing glassine release paper in which a coating liquid mainly composed of an acrylic ester resin is applied to base paper using a coating machine selected from a size press, a gate roll coater, and a bar coater installed in the middle of the dryer of a papermaking machine, and the base paper is compressed to obtain glassine paper, to which a release agent is applied.

Japanese Patent Application Publication No. 09-302599 Japanese Patent Application Publication No. 05-279996 Japanese Patent Application Publication No. 09-111699

Such release paper is required to have excellent calendering processability of the base paper and high smoothness of the surface of the release paper. However, for example, the release papers disclosed in Patent Document 1 and Patent Document 3 have insufficient smoothness of the release agent layer of the release paper. When the adhesive layer is peeled off from the release paper together with the surface substrate in an adhesive tape using such release paper with insufficient smoothness, fine irregularities are generated on the surface of the adhesive layer, etc., and the appearance of the exposed adhesive layer is impaired. In addition, although the release paper base paper disclosed in Patent Document 2 also uses glassine paper, etc. as the base paper, it is insufficient to balance the calendering processability of the release paper base paper and the surface smoothness when made into release paper, and there is room for improvement. Thus, conventional release papers have a problem in that they cannot maintain both the calendering processability of the release paper base paper and the surface smoothness when made into release paper at a high level. Such a problem is particularly noticeable when glassine paper is used as the base paper, and there is room for improvement.

The present invention was made in consideration of these circumstances, and its main objective is to provide a release paper base paper, release paper, and adhesive tape that can be used to produce a release paper that is not only excellent in calendar processability but also has high smoothness, as well as a method for producing the release paper base paper.

As a result of intensive research into achieving the above-mentioned object, the inventors discovered that a release paper base material could be made that includes a paper substrate and a coating layer that is laminated on at least a portion of the surface of the paper substrate and that contains (A) a styrene-based resin and (B) a resin with a glass transition temperature (Tg) of 100°C or higher, and thus completed the present invention.

In other words, the present invention is as follows.

(1)
The release paper base paper comprises a paper substrate and a coating layer laminated on at least a portion of the surface of the paper substrate, the coating layer comprising (A) a styrene-based resin and (B) a resin having a glass transition temperature (Tg) of 100°C or higher.
(2)
The release paper base paper according to (1), wherein the component (B) is an olefin-based resin.
(3)
The release paper base paper according to (1) or (2), wherein the component (A) is at least one selected from the group consisting of a styrene-olefin resin, a styrene-acrylic resin, and a styrene-methacrylic resin.
(4)
The release paper base paper according to any one of (1) to (3), comprising 40 parts by mass or more and 200 parts by mass or less of the (B) component relative to 100 parts by mass of the (A) component.
(5)
A release paper comprising the release paper base paper according to any one of (1) to (4) above and a release agent layer laminated on at least a part of the surface of the coating layer of the release paper base paper.
(6)
The release paper according to (5), wherein the surface of the release agent layer has a smoothness of 1050 seconds or more according to JIS P 8155.
(7)
The release paper according to (5) or (6), wherein the surface of the release agent layer has an arithmetic mean roughness (Ra) according to JIS B 0601 of 0.80 μm or less.
(8)
The adhesive tape includes a tape substrate, an adhesive layer laminated on at least a portion of a surface of the tape substrate, and a release paper according to any one of (5) to (7) laminated on a surface of the adhesive layer opposite to the tape substrate.
(9)
The method for producing a release paper base paper includes a step of applying a coating liquid containing (A) a styrene-based resin, which is a latex, and (B) a resin having a glass transition temperature (Tg) of 100°C or higher, to at least a part of the surface of a paper substrate to form a coating layer.

The present invention provides a release paper base paper, release paper, and adhesive tape that can be used to produce a release paper that is not only excellent in calendering processability but also has high smoothness, as well as a method for producing the release paper base paper.

FIG. 1 is a schematic cross-sectional view of a release paper base paper according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the release paper according to the present embodiment. FIG. 3 is a schematic cross-sectional view of the pressure-sensitive adhesive tape according to this embodiment.

The following describes in detail the form for carrying out the present invention (hereinafter, simply referred to as the "present embodiment"). The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out with appropriate modifications within the scope of its gist.

In the drawings, the same elements are given the same reference numerals, and duplicate explanations are omitted. Furthermore, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

In addition, in this specification, unless otherwise specified, "(meth)acrylic" includes methacryl and acrylic. For example, (meth)acrylic means methacryl, acrylic, or both. The same applies to other similar terms such as "(meth)acrylate."

＜Release paper base paper＞

Figure 1 is a schematic cross-sectional view of the release paper base paper according to this embodiment.

The release paper base paper 10 according to this embodiment includes a paper substrate 11 and a coating layer 12 formed on the surface of the paper substrate 11 and containing (A) a styrene-based resin and (B) a resin with a glass transition temperature (Tg) of 100°C or higher. By providing a coating layer 12 containing specific components (A) and (B) on the surface of the paper substrate 11, it is possible to obtain a release paper base paper 10 that is not only excellent in calendering processability but also has high smoothness.

(Paper base material)

The paper substrate 11 (base paper) is not particularly limited, and examples thereof include glassine paper, semi-glassine paper, fine paper, kraft paper, clay-coated paper, medium-quality paper, alkaline paper, coated paper, paperboard, white paperboard, and so-called dust-free paper that generates little dust. Among these, glassine paper and semi-glassine paper are preferred, and glassine paper is more preferred. In conventional release papers, when glassine paper is used as the base paper, there is a significant problem in that the release paper base paper does not sufficiently balance the calendering processability and the surface smoothness when made into a release paper. However, according to the present embodiment, even when glassine paper or the like is used as the paper substrate 11, a release paper base paper 10 can be made that not only has excellent calendering processability, but also has high smoothness.

In general, in the manufacturing process of glassine paper, the pulp is beaten and then calendered to fluff the fibers that make up the paper and eliminate the gaps between the fibers (reducing the gaps). Therefore, glassine paper can have higher barrier properties and transparency than other types of paper such as fine paper. Such glassine paper is often used as the base paper for release paper because it is possible to allow the release agent (e.g., silicone-based release agent such as silicone-based resin) to remain on the surface of the release paper base paper without penetrating into the base paper. However, as a result of the inventors' intensive research, problems arise in that the glassine paper has a fuzzy surface, which creates fine irregularities on the surface and reduces smoothness. If such glassine paper with poor smoothness is used as the base paper for release paper, fine irregularities will also be created on the surface of the release paper, resulting in a release paper with poor surface smoothness.

However, even when the release paper base paper 10 according to this embodiment uses a base paper with a high degree of beating and fluffy surface fibers, such as glassine paper, the coating layer 12 described below is provided thereon to reduce the roughness of the release paper surface and prevent a decrease in the smoothness of the surface. As a result, a release paper base paper 10 can be realized that not only has excellent calendering properties, but also has high smoothness.

In addition, in this embodiment, when glassine paper is used as the paper substrate 11, as described above, the surface is fluffy, so that barrier properties can be ensured. Then, as described below, when the release agent layer 21 is formed on the surface of the coating layer 12, it can be placed firmly on the surface. Furthermore, an additional advantage of ensuring transparency can be imparted.

The paper substrate 11 may be subjected to various surface treatments such as heat treatment and corona discharge treatment in advance to enhance adhesion to the coating layer 12. The conditions for such surface treatments are not particularly limited as long as they are within the range in which the effects of this embodiment can be obtained, and suitable conditions can be selected as appropriate.

The pulp constituting the paper base material 11 may be, for example, wood pulp such as softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), softwood bleached sulfite pulp (NBSP), hardwood bleached sulfite pulp (LBSP), etc. Among these, softwood bleached kraft pulp (NBKP) and hardwood bleached sulfite pulp (LBKP) are preferred.

The pulp content of the paper base material 11 is not particularly limited, but is preferably 60% by mass or more and 100% by mass or less. The lower limit of this content is more preferably 65% by mass or more, and even more preferably 70% by mass or more. The upper limit of this content is more preferably 98% by mass or less, and even more preferably 97% by mass or less.

When the pulp constituting the paper base material 11 contains softwood bleached kraft pulp (NBKP) and/or hardwood bleached kraft pulp (LBKP), from the viewpoint of smoothness, the content ratio of softwood bleached kraft pulp (NBKP)/hardwood bleached kraft pulp (LBKP) (pulp N/L ratio, mass ratio) is preferably 80/20 to 0/100 (i.e. 4 or less), more preferably 70/30 to 0/100 (i.e. 7/3 or less), and even more preferably 50/50 to 0/100 (i.e. 1 or less).

The thickness of the paper base material 11 is preferably 40 μm or more and 300 μm or less. By making the thickness 40 μm or more, the occurrence of wrinkles during the production of the release paper 20 can be suppressed, and the suitability for the punching process during label production can be improved. Furthermore, by making the thickness 300 μm or less, the rigidity does not become too high, and the handling properties are not reduced. This thickness can be measured in accordance with JIS P 8118.

The degree of beating of the base paper of the paper substrate 11 is preferably 20°SR or more and 75°SR or less. The lower limit of the degree of beating is more preferably 25°SR or more, and even more preferably 30°SR or more. The upper limit of the degree of beating is more preferably 70°SR or less, and even more preferably 65°SR or less. When using base paper with a degree of beating in such a range, the beating process results in a fuzzy surface with advanced filbillization. Therefore, conventional release paper using such base paper is prone to problems such as poor smoothness. However, according to the present embodiment, even with base paper with such a degree of beating, it is possible to realize a release paper base paper 10 that can be made into a release paper that is not only excellent in calendar processability but also has high smoothness, which is preferable. Base paper having such a degree of beating is not particularly limited, but examples thereof include glassine paper. This degree of beating can be measured using a Shopper-Rigler type beating tester in accordance with JIS P 8121.

The basis weight of the paper base material 11 is preferably 35 g/m ² or more and 120 g/m ² or less. The lower limit of this basis weight is more preferably 50 g/m ² or more, even more preferably 55 g/m ² or more, and even more preferably 60 g/m ² or more. The upper limit of this basis weight is more preferably 100 g/m ² or less, even more preferably 90 g/m ² or less, and even more preferably 80 g/m ² or less. By controlling this basis weight within such a range, the suitability for papermaking is further improved.

(coating layer)

The coating layer 12 contains (A) a styrene-based resin and (B) a resin with a glass transition temperature (Tg) of 100°C or higher. By containing the components (A) and (B), it is possible to realize a release paper base paper 10 that can achieve both calendering processability and surface smoothness when made into a release paper at a high level that was previously unattainable.

Component (A) is a styrene-based resin. The monomer of the styrene-based resin of component (A) may be styrene alone or may contain other monomers. Examples of other monomers include olefins such as ethylene, propylene, 1-butene, 2-methyl-1-butene, 2-methyl-1-pentene, 1-hexene, 2,2-dimethyl-1-butene, 2-methyl-1-hexene, 4-methyl-1-pentene, 1-heptene, 3-methyl-1-hexene, 2,2-dimethyl-1-pentene, 3,3-dimethyl-1-pentene, 2,3-dimethyl-1-pentene, 3-ethyl-1-pentene, 2,2,3-trimethyl-1-butene, 1-octene, and 2,2,4-trimethyl-1-octene; and (meth)acrylic acid alkyl esters such as (meth)acrylic acid, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and stearyl (meth)acrylate. The styrene content is preferably 50 mol% or more of the total amount of monomers.

Specific examples of the styrene-based resin of component (A) include styrene resin, styrene-olefin-based resin (e.g., styrene-butadiene-based resin, etc.), styrene-(meth)acrylic resin, etc. Among these, at least one selected from the group consisting of styrene-olefin-based resin, styrene-acrylic resin, and styrene-methacrylic resin is preferable, and styrene-olefin-based resin or styrene-acrylic resin is more preferable.

The glass transition temperature (Tg) of component (A) is preferably -30°C or higher and 70°C or lower. The lower limit of this glass transition temperature (Tg) is more preferably -20°C or higher, and even more preferably -10°C or higher. The upper limit of this glass transition temperature (Tg) is more preferably 50°C or lower. By controlling the lower limit of the glass transition temperature (Tg) within this range, processing can be performed without sticking to the calendar roll. By controlling the upper limit of the glass transition temperature (Tg) within this range, it is possible to effectively soften the material during calendar processing, and further improve the surface smoothness when it is made into a release paper.

Unless otherwise specified, the glass transition temperature (Tg) can be measured by differential scanning calorimetry (DSC) under the following measurement conditions: heating from 40°C to 230°C at 10°C/min, then cooling, and heating again from -80°C to 230°C.

Component (B) is a resin with a glass transition temperature (Tg) of 100°C or higher. By using components (A) and (B) in combination, the amount of coating (wet, dry) that can be applied to the paper substrate 11 can be increased, resulting in a release paper base paper 10 that not only has excellent calendering properties, but also has high smoothness.

The glass transition temperature (Tg) of component (B) may be 100°C or higher, but the upper limit is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. By controlling the glass transition temperature (Tg) within this range, the film-forming properties of the coating layer 12 are improved, and the coating layer 12 can be made to be one that does not collapse even when the surface is rubbed.

The type of resin of component (B) is not particularly limited, but examples thereof include thermoplastic resins such as olefin resins (e.g., polyethylene resins, polypropylene resins, etc.), vinyl chloride resins, vinylidene chloride resins, polyester resins, polyamide resins, and nylon. Among these, olefin resins are preferable. Examples of monomers of olefin resins include α-olefins such as ethylene, propylene, 1-butene, 2-methyl-1-butene, 2-methyl-1-pentene, 1-hexene, 2,2-dimethyl-1-butene, 2-methyl-1-hexene, 4-methyl-1-pentene, 1-heptene, 3-methyl-1-hexene, 2,2-dimethyl-1-pentene, 3,3-dimethyl-1-pentene, 2,3-dimethyl-1-pentene, 3-ethyl-1-pentene, 2,2,3-trimethyl-1-butene, 1-octene, and 2,2,4-trimethyl-1-octene. Among these, ethylene, propylene, etc. are preferred. These monomers may be used alone or in combination of two or more. Specific examples of component (B) are more preferably polyethylene resin, polypropylene resin, etc.

The ratio of the (A) component and the (B) component in the coating layer 12 is not particularly limited, but it is preferable that the (B) component is 40 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the (A) component. The lower limit of the (B) component per 100 parts by mass of the (A) component is more preferably 50 parts by mass or more, and even more preferably 90 parts by mass or more. In addition, the upper limit of the (B) component per 100 parts by mass of the (A) component is more preferably 150 parts by mass or less, and even more preferably 130 parts by mass or less. By controlling the lower limit of the (B) component to such a range, tack can be reduced, so that the material can be processed without sticking during calendar processing, and the calendar processability is further improved. In addition, by controlling the upper limit of the (B) component to such a range, high film-forming properties are obtained, so that the coating layer 12 is easily formed on the surface of the paper base material 11, and the smoothness of the surface when the paper is made into a release paper is further improved.

The thickness of the coating layer 12 is preferably 0.5 μm or more and 50 μm or less. The lower limit of this thickness is more preferably 1 μm or more. Also, the upper limit of this thickness is more preferably 10 μm or less. By controlling the lower limit of this thickness within this range, it is possible to effectively suppress the penetration of the release agent described below into the paper substrate 11. Also, by controlling the upper limit of this thickness within this range, it is possible to prevent the thickness from becoming unnecessarily thick and keep it at a practical thickness.

Various additives and various auxiliary agents such as fillers such as clay, silica, calcium carbonate, titanium oxide, and zinc oxide, dispersants, thickeners, water retention agents, defoamers, water resistance agents, colorants, and printability improvers may be added to the coating layer 12 as desired, within the scope that does not impair the effects of this embodiment.

<Release paper base paper manufacturing method>

A suitable method for producing the release paper base paper 10 according to this embodiment includes a method for producing the release paper base paper 10, which includes a step of applying a coating liquid containing (A) a styrene-based resin (styrene-based latex resin) that is a latex and (B) a resin with a glass transition temperature (Tg) of 100°C or higher to at least a portion of the surface of the paper substrate 11 to form a coating layer 12.

The coating liquid containing the (A) component and the (B) component can be applied to one or both sides of the paper substrate 11 to form a coating layer 12 on one or both sides. There are no particular limitations on the coating method, and a conventionally known method can be used, such as a method of applying a coating liquid containing a resin component onto the paper substrate 11 and drying it to form the coating layer 12. For example, a method of coating using an appropriate coating device such as a blade coater, air knife coater, rod blade coater, bar blade coater, gravure coater, bar coater, multi-stage roll coater, roll coater, reverse roll coater, curtain coater, spray coater, gate roll coater, size press coater, or shim sizer can be used.

In this respect, the (A) component is suitable for application, for example, because it can increase the amount of coating (g/m ² ) on the surface of the paper substrate 11 during the coating process. The latex referred to here refers to a solvent in which resin particles are stably dispersed. From this perspective, the solvent is preferably water or alcohols (e.g., ethanol, isopropanol, etc.), and more preferably water. The solvent may be used alone or in combination of two or more. Even when two or more are used in combination, it is preferable that the solvent is an aqueous solvent. In addition, when the (A) styrene-based resin is a latex, additives such as pH adjusters, defoamers, preservatives, crosslinking agents, chelating agents, oxygen scavengers, dispersants, and antiaging agents that are usually blended in the field of latex may be blended.

Component (B) may be used as a solution dissolved or dispersed in a solvent, but is preferably an emulsion obtained by emulsion polymerization or the like of the monomers that make up component (B). Component (B) being an emulsion can reduce the penetration force into the paper substrate 11 compared to solvent-type components, making it easier to form a coating layer 12 on the surface of the paper substrate 11 without penetrating into the interior. In addition, since the water resistance of the coating layer 12 is improved, when a release agent layer 21 is provided on the surface of the coating layer 12 as described below, the curing property of the silicone is not impaired, and it can be suitably used as a release paper 20.

From the same viewpoint as the above-mentioned component (B), it is preferable that the component (A) is also an emulsion. In other words, by having both the components (A) and (B) contained in the coating liquid as emulsions, the above-mentioned effects are further improved.

Furthermore, the coating liquid may contain components that can be blended into the coating layer 12 described above. For example, in addition to the components (A) and (B), various additives and various auxiliary agents such as fillers such as clay, silica, calcium carbonate, titanium oxide, and zinc oxide, dispersants, thickeners, water retention agents, defoamers, water resistance agents, colorants, and printability improvers may be added as desired within a range that does not impair the effects of this embodiment.

In addition, the coating amount (dry) of the coating liquid that becomes the coating layer 12 is not particularly limited, but is preferably 1 g/m ² or more and 10 g/m ² or less. The lower limit of this coating amount is more preferably 2 g/m ² or more, and even more preferably 3 g/m ² or more. In addition, the upper limit of this coating amount is more preferably 8 g/m ² or less, and even more preferably 7 g/m ² or less. By controlling the lower limit of this coating amount to such a range, the smoothness is further improved. In addition, by controlling the upper limit of this coating amount to such a range, tack can be effectively suppressed, and therefore the calendering processability is further improved.

After application, steps such as humidity control and cutting may be carried out as necessary.

＜Release paper＞

Figure 2 is a schematic cross-sectional view of the release paper according to this embodiment.

The release paper 20 according to this embodiment includes the release paper base paper 10 described above and a release agent layer 21 laminated on at least a portion of the surface of the coating layer 12 of the release paper base paper 10. By providing the release agent layer 21 on the surface of the coating layer 12, it can be suitably used as the release paper 20.

Although not shown, the release paper 20 may be a double-sided release paper by providing the coating layer 12 and the release agent layer 21 on both sides of the paper base material 11. Furthermore, the release paper 20 may be provided with a curl suppression layer or the like on the side of the paper base material 11 opposite to the side on which the coating layer 12 and the release agent layer 21 are provided. There are no particular limitations on the curl suppression layer, and a known layer may be used.

(Release agent layer)

The release agent contained in the release agent layer 21 is not particularly limited, and examples thereof include silicone-based resins, fluorine-based resins, alkyd resins, long-chain alkyl resins, various waxes, and the like. Among these, it is preferable that the release agent be a silicone-based resin from the viewpoint of excellent release properties.

Examples of silicone-based resins include homopolymers or copolymers of trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, diphenyldichlorosilane, phenyltrichlorosilane, methylvinyldichlorosilane, etc. These may be used alone or in combination of two or more types.

Silicone-based resins can be used in any form, including solvent-based, solventless, and emulsion-based, but emulsion and solventless types are preferred.

The thickness of the release agent layer 21 is preferably 0.01 μm or more and 10 μm or less. It is more preferable that the lower limit of this thickness is 0.1 μm or more. It is more preferable that the upper limit of this thickness is 5 μm or less.

The release agent layer 21 can be formed by applying and heating a coating liquid containing the release agent described above to a portion of the surface of the coating layer 12 of the release paper base paper 10 to harden the coating liquid. There are no particular limitations on the coating method, and it is possible to employ a coating method using an appropriate coating device, such as a blade coater, air knife coater, rod blade coater, bar blade coater, gravure coater, bar coater, or multi-stage roll coater.

The coating amount (dry) of the coating solution containing the release agent is preferably 0.4 g/ ^m2 or more and 3.0 g/ ^m2 or less. The lower limit of this coating amount is more preferably 0.6 g/ ^m2 or more, and even more preferably 0.8 g/ ^m2 or more. The upper limit of this coating amount is more preferably 2.0 g/ ^m2 or less, and even more preferably 1.5 g/ ^m2 or less. By controlling the coating amount within this range, it is possible to obtain a release force that is more suitable for the release paper.

The surface smoothness of the release agent layer 21 can be preferably 1050 seconds or more, more preferably 1500 seconds or more, and even more preferably 2000 seconds or more in accordance with JIS P 8155 as a preferred embodiment. The surface roughness of the release agent layer 21 can be preferably 0.80 μm or less, more preferably 0.70 μm or less in accordance with JIS B 0601 as a preferred embodiment. The lower limit of the arithmetic mean roughness (Ra) of the release agent layer 21 is not particularly limited, but is preferably 0.10 μm or more. The arithmetic mean roughness (Ra) can be measured, for example, by a contact surface roughness meter. The "surface" here refers to the surface of the release agent layer 21 of the release paper 20. It is preferable that the release paper 20 has both smoothness and Ra measured by a contact surface roughness meter. In this embodiment, by using a release paper base paper 10 in which a paper substrate 11 is provided with a coating layer 12 containing components (A) and (B), it is possible to impart such high smoothness to the release paper 20.

Because of the above-mentioned advantages, suitable examples of uses for the release paper 20 include protecting the adhesive layer of adhesive tapes, labels, etc. (protecting the adhesive surface of adhesive products), but it is particularly suitable for use with adhesive tapes, which will be described later.

＜Adhesive tape＞

Figure 3 is a schematic cross-sectional view of the adhesive tape according to this embodiment.

The adhesive tape 30 according to this embodiment includes a tape substrate 31, an adhesive layer 32 laminated on the surface of the tape substrate 31, and the above-mentioned release paper 20 laminated on the surface of the adhesive layer 32 opposite the tape substrate 31. The adhesive layer 32 may be formed on at least a part of the surface of the tape substrate 31. The tape substrate 31 can be bonded to the surface of the release agent layer 21 of the release paper 20 described above via the adhesive layer 32, thereby making it suitable for use as the adhesive tape 30. That is, the adhesive tape 30 is formed by laminating the paper substrate 11, the coating layer 12, the release agent layer 21, the adhesive layer 32, and the tape substrate 31 in this order.

(Tape substrate)

The tape substrate 31 may be a substrate made of paper, resin, or other raw materials. Examples of paper substrates include coated paper such as fine paper, art paper, and coated paper, foil paper, colored fancy paper, impregnated paper, cellophane, and dust-free paper. Examples of resin substrates include resin films such as polyester, polyethylene terephthalate, polyethylene, polylactic acid, polyurethane urea, vinyl chloride, polystyrene, polytetrafluoroethylene, polyimide, ABS, and polyester. The material of the tape substrate 31 may be selected appropriately depending on the application and environment in which the adhesive tape 30 is to be used.

(Adhesive layer)

The adhesive contained in the adhesive layer 32 is not particularly limited, and examples include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, epoxy-based adhesives, polyester-based adhesives, urethane-based adhesives, polyolefin-based adhesives, vinyl ether-based adhesives, etc. Among these, acrylic-based adhesives and urethane-based adhesives are preferred, with acrylic-based adhesives being more preferred, as they have excellent transparency and good durability.

Acrylic adhesives may be mainly composed of n-butyl acrylate, 2-ethylhexyl acrylate, etc., and may be composed of methyl (meth)acrylate, ethyl (meth)acrylate, styrene, acrylonitrile, vinyl acetate, etc., as components that impart cohesive strength to the acrylic adhesive. In addition, adhesives may be used that contain a polymer obtained by copolymerizing functional monomers that serve as crosslinking points, such as (meth)acrylic acid, acrylamide derivatives, hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, etc., and a suitable crosslinking agent.

The adhesive may also be a solvent-free adhesive such as a solvent-based adhesive, an emulsion-based adhesive, or a hot-melt-based adhesive, or an energy ray-curable adhesive that is cured by irradiation with energy rays and becomes removable. Furthermore, the adhesive may contain crosslinking agents, tackifiers, softeners, anti-aging agents, fillers, colorants such as dyes or pigments, etc., as necessary.

The thickness of the adhesive layer 32 is preferably 5 μm or more and 200 μm or less. The lower limit of this thickness is more preferably 10 μm or more. Also, the upper limit of this thickness is more preferably 100 μm or less. By controlling the lower limit of this thickness within this range, sufficient adhesive strength can be ensured and the thickness of the adhesive layer 32 can be made uniform. Also, by controlling the upper limit of this thickness within this range, drying after application of the adhesive can be completed in a short time, the adhesive does not overflow from the adhesive tape 30, and the yield is good and production efficiency is improved.

Furthermore, since the adhesive tape 30 according to this embodiment uses a release paper 20 with high smoothness, when the adhesive layer 32 is peeled off from the release paper 20 together with the tape substrate 31, fine irregularities do not occur on the surface of the adhesive layer 32, and the aesthetic appearance of the surface of the adhesive layer 32 is not impaired. From this perspective, it is more preferable that the haze value of the adhesive layer 32 is 15% or less as a suitable aspect of the adhesive tape according to this embodiment. By being able to keep the haze value of the adhesive layer 32 within this range, it is suitable as a material for tapes for sales promotion and advertising, such as POP labels that are directly visible to consumers.

The adhesive tape 30 can be molded into an appropriate shape, such as a sheet, tape, or label, and used for a variety of applications similar to those of conventional adhesive tapes, such as bonding adherends.

Although not shown, a conventionally known laminate film may be further provided on the surface of the adhesive tape 30 to protect the adhesive tape 30 and prevent discoloration.

In order to improve the fixation of toner, ink, etc., a print-receiving layer may be further provided on the surface of the adhesive tape 30 opposite the adhesive layer 32 (the surface of the outermost layer). The print-receiving layer can be provided, for example, by applying various printing coating agents. As the printing coating agent, preferably, an acrylic resin or a polyester resin, or a printing coating agent using both of them, etc. can be mentioned.

Furthermore, in order to protect toner, ink, etc., the adhesive tape 30 may be provided with a coating layer by applying a coating agent onto the surface of the adhesive tape 30 or the surface of the print-receiving layer (the surface of the outermost layer). Then, if necessary, the adhesive tape 30 may be printed on or processed by half-cutting, cutting, etc. to obtain labels, etc.

The adhesive tape 30 can be manufactured by applying an adhesive-containing coating liquid to the surface of the release agent layer 21 of the release paper 20 described above by a known method, drying the coating liquid to form an adhesive layer 32, and then laminating the tape substrate 31 onto the adhesive layer 32. Furthermore, a winding process for winding up the adhesive tape 30 may be performed as necessary.

As explained above, the release paper base paper 10 according to this embodiment not only has excellent calendering properties, but also has the advantage of having a high surface smoothness when made into the release paper 20. Therefore, the release paper base paper 10 can be suitably used as the release paper 20, and the adhesive tape 30 using the release paper 20 can be suitably used, for example, as various overlamination labels, and further, as various labels for management purposes (e.g., labels for managing goods, labels for process management, labels for logistics management, etc.), stationery and office supplies (concealing labels, fancy labels, etc.), sales promotion and advertising purposes (e.g., POP labels), and various other play equipment applications.

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples in any way.

Unless otherwise specified, the processing and measurements in this example were carried out in an environment of 23°C and 50% relative humidity.

<Example 1>

First, glassine paper (beating degree: 42°SR, pulp N/L ratio (mass ratio): 30/70, basis weight: 64 g/m ² ) was prepared as the paper base material 11, and a coating liquid was prepared by mixing 100 parts by mass of styrene butadiene 1 (styrene-butadiene latex resin, manufactured by Nippon A&L Co., Ltd., "Smartex SN-309R") and 124 parts by mass of olefin emulsion 1 (polyolefin emulsion, manufactured by Unitika Ltd., "Arrowbase DC-1010") to the solid content (mass %) shown in Table 1 using a hand coater. This coating liquid was applied to the surface of the paper base material 11 using a No. 10 wire bar so as to satisfy the coating conditions shown in Tables 1 and 2. The paper base material 11 was then dried at 120°C for 120 seconds to form a coating layer 12 on the surface of the paper base material 11. This was then passed through rolls twice at 60° C. and 10 MPa for calendaring to obtain a release paper base paper 10 having the structure shown in FIG.

Finally, a solventless silicone was applied to the surface of the coating layer 12 of the release paper base paper 10 so that the dry coating amount was 1.0 g/ ^m2 , and then the resultant was heated at 150°C for 30 seconds to form a release agent layer 21, thereby obtaining a release paper 20 having the structure shown in Figure 2.

<Examples 2-7, Comparative Examples 1-8>

A release paper base paper and release paper were prepared in the same manner as in Example 1, except that the formulation and coating amount were changed to those shown in Table 1 and Table 2, respectively. Note that in Comparative Example 4, the viscosity of the coating liquid used to form the coating layer 12 was too high, so the coating liquid could not be applied and the release paper base paper could not be prepared.

The components in Table 1 are as follows.
Component (A) - "Styrene butadiene 1" (styrene-butadiene latex resin, manufactured by Nippon A&L Co., Ltd., "Smartex SN-309R", Tg = -3°C)
- "Styrene butadiene 2" (styrene-butadiene latex resin, manufactured by Nippon A&L Co., Ltd., "Smartex SR-102", Tg = 21°C)
- "Styrene Acrylic 1" (styrene-acrylic latex resin, manufactured by Henkel Japan, "Aquence BC900F", Tg = -7.8°C)
"PVA" (Polyvinyl alcohol, manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., "J Poval AM-20", Tg = 76 ° C.)
Component (B) - "Olefin emulsion 1" (polyolefin emulsion, manufactured by Unitika Ltd., "Arrowbase DC-1010", Tg = 125°C)
"Olefin Emulsion 2" (polyethylene emulsion, manufactured by Toho Chemical Industry Co., Ltd., "Hitec E-6700", Tg = 130°C)
"Olefin Emulsion 3" (polyethylene emulsion, manufactured by Toho Chemical Industry Co., Ltd., "Hitec E-6314", Tg = 126°C)
"Olefin Emulsion 4" (polyethylene emulsion, manufactured by Toho Chemical Industry Co., Ltd., "Hitec E-8237", Tg = 60°C)

＜Evaluation method＞

(calendering processability)

The calendering processability test of the release paper base paper 10 was carried out as follows. First, a 21 cm x 29.7 cm sample (release paper base paper 10) was fed between a pair of metal rolls of a calender along its length and passed between the metal rolls twice at 60°C, 10 MPa, and 5 m/min (calendering). The condition after passing was visually observed, and if the coating layer 12 stuck to the metal roll of the calender and did not peel off, it was rated as "X". If the coating layer 12 stuck to the metal roll of the calender slightly but peeled off easily, or did not stick at all, it was rated as "O".

(Suitability for silicone application)

The release paper base paper 10 was tested for silicone coating suitability, which also served to evaluate barrier properties. First, a solventless silicone was applied to the surface of the coating layer 12 of the sample (release paper base paper 10) so that the coating amount was 1.0 g/ ^m2 , and then a heat curing treatment was performed under conditions of 150°C and 30 seconds to form a release agent layer 21. Then, using a printability tester (RI tester, manufactured by IHI Machine Systems Co., Ltd., "RI-2"), writing was performed on the surface with an oil-based marker, and if ink repellency was observed visually, it was evaluated as "○". If ink repellency was not observed, it was evaluated as "×". In the table, for Comparative Example 1, the calendering process was "×", and the silicone coating suitability test could not be performed (see "-" in Table 2).

(Smoothness)

In the surface smoothness test of the release paper 20, the smoothness (seconds) was determined by a test conforming to JIS P 8155. Specifically, the surface smoothness (seconds) of the release agent layer 21 of the release paper 20 formed by silicone application was measured using a digital Oken-type air permeability smoothness tester manufactured by Asahi Seiko Co., Ltd. Note that for Comparative Examples 1 and 5 to 7 in the table, silicone application (formation of the release agent layer 21) was not possible in the silicone application suitability test, and therefore sufficient wetting was not obtained to perform the smoothness test, and this test could not be performed (see "-" in Table 2).

(Smoothness, Ra)

In the surface smoothness test of the release paper 20, a contact surface roughness meter was used to measure the arithmetic mean roughness (Ra) of the surface of the release agent layer 21 after two calendaring processes, and the surface smoothness was evaluated. Specifically, in accordance with JIS B 0601, a contact surface roughness meter (manufactured by Mitutoyo Corporation, "SV-3000", measurement distance 10 mm) was used to determine the arithmetic mean roughness (Ra) of the surface to be measured. Note that for Comparative Examples 1 and 5 to 7 in the table, silicone application (formation of the release agent layer 21) could not be performed in the silicone application suitability test, and therefore this test could not be performed (see "-" in Table 2).

(Adhesive tape manufacturing)

Furthermore, adhesive tapes 30 were produced for Examples 1 to 7 and Comparative Examples 2, 3, and 8. First, an acrylic adhesive was applied to the surface of the obtained release paper 20, and the resulting coating was dried to form an adhesive layer 32 (thickness 20 μm). Next, a PET film with a polyester-based easy-adhesion layer (thickness 1 μm) formed on one side was prepared as the tape substrate 31, and the polyester-based easy-adhesion layer of the tape substrate 31 and the adhesive layer 32 were bonded together to obtain an adhesive tape 30 having the structure shown in FIG. 3.

(Haze value)

For Examples 1 to 7 and Comparative Examples 2, 3, and 8, the release paper 20 was peeled off from the obtained adhesive tape 30, and the haze value (%) of the exposed adhesive layer 32 was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., "NDH-5000") in accordance with JIS K 7136:2000.

The formulations, coating amounts, and evaluation results of each example and comparative example are shown in Tables 1 and 2. Note that units in the tables are by weight unless otherwise specified.

From the above, it was confirmed that this example at least provides a release paper base paper that not only has excellent calendering properties, but also has high smoothness.

10: Release paper base paper,
11: Paper base material,
12: coating layer,
20: Release paper,
21: release agent layer,
30: adhesive tape,
31: Tape substrate,
32: Adhesive layer

Claims (9)

A paper substrate;
a coating layer laminated on at least a portion of the surface of the paper base material, the coating layer including (A) a styrene-based resin and (B) a resin having a glass transition temperature (Tg) of 100° C. or higher;
A release paper base paper comprising: The component (B) is an olefin-based resin.
The release paper base paper according to claim 1. The component (A) is at least one selected from the group consisting of a styrene-olefin resin, a styrene-acrylic resin, and a styrene-methacrylic resin.
The release paper base paper according to claim 1 or 2. The (B) component is contained in an amount of 40 parts by mass or more and 200 parts by mass or less relative to 100 parts by mass of the (A) component.
The release paper base paper according to any one of claims 1 to 3. A release paper base paper according to any one of claims 1 to 4,
a release agent layer laminated on at least a portion of the surface of the coating layer of the release paper base paper;
including a release paper. The surface of the release agent layer has a smoothness of 1050 seconds or more according to JIS P 8155.
The release paper of claim 5. The surface of the release agent layer has an arithmetic average roughness (Ra) of 0.80 μm or less according to JIS B 0601.
The release paper according to claim 5 or 6. A tape substrate;
a pressure-sensitive adhesive layer laminated on at least a portion of a surface of the tape substrate;
The release paper according to any one of claims 5 to 7, laminated on a surface of the pressure-sensitive adhesive layer opposite to the tape substrate;
Including, adhesive tape. The method includes a step of applying a coating liquid containing (A) a styrene-based resin, which is a latex, and (B) a resin having a glass transition temperature (Tg) of 100° C. or higher, to at least a part of the surface of a paper substrate to form a coating layer.
A method for producing release paper base paper.