JP-2026075742-A - Base paper for release paper and release paper

Abstract

[Problem] The present invention provides a base paper for release paper in which the sealing layer can be easily separated and easily recycled. [Solution] The present invention relates to a base paper for release paper, wherein a sealing layer is laminated on at least one side of a base paper, and the sealing layer is a resin layer formed from a sealing layer forming composition mainly composed of a water-based polyurethane resin. Furthermore, in the release paper of the present invention, the release layer is laminated on the side of the release paper base paper opposite to the side of the sealing layer on which the base paper is provided. [Selection Diagram] Figure 1

Inventors

• 佐々木 将材
• 石原 直樹
• 佐藤 愛佳

Assignees

• 株式会社サンエー化研

Dates

Publication Date

20260511

Application Date

20241023

Claims (2)

1. A base paper for release paper, comprising a base paper with a sealing layer laminated on at least one surface, wherein the sealing layer is a resin layer formed from a sealing layer-forming composition mainly composed of a water-based polyurethane resin.
2. A release paper according to claim 1, wherein the release layer is laminated on the side opposite to the side of the sealing layer on which the base paper is provided.

Description

This invention relates to base paper for release paper and release paper. Release paper is used as a backing to protect the adhesive surface of adhesive labels, stickers, tapes, etc., from the adhesion of dirt and other debris. The surface that comes into contact with the adhesive is coated with a release agent such as silicone resin. Conventional release paper is manufactured by coating the surface of base paper such as polyethylene laminate paper, glassine paper, clay-coated paper, or clear-coated paper with a release agent. However, these release agents are used after dilution with organic solvents such as toluene, which poses an environmental problem. Therefore, in recent years, there has been increasing demand for water-based emulsion-type silicone resins and solvent-free silicone resins. Furthermore, since silicone resin used as a release agent is very expensive, it is necessary for the release paper base to minimize the penetration of the silicone resin coating solution into the base paper in order to enable uniform application of a small amount of silicone resin coating solution. However, in recent years, from the perspective of resource conservation, recyclability has also become a requirement. To suppress the penetration of release agents such as silicone resin, a release paper base with polyethylene laminated to the paper base is preferable. However, it has the disadvantage of being unsuitable for recycling because it is difficult to separate the release paper after use. To improve upon the above drawbacks, a release paper base is known, comprising a base paper having a sealing layer containing at least a pigment component and an adhesive component on at least one surface of the base paper, wherein the median diameter (D50) of the pigment component, as measured by laser diffraction using a scattering particle size distribution analyzer, is 2.0 to 7.0 μm, the adhesive component contains at least synthetic resin latex, and the amount of synthetic resin latex blended with 100 parts by mass of the pigment component (absolutely dry) is 8 to 20 parts by mass (absolutely dry) (see Patent Document 1). Furthermore, a release paper for adhesive labels is known, characterized by a tightness of 0.9 to 1.1 when an underlayer containing a tackifier with a softening point of 170°C or lower, a sealing layer containing a water-soluble resin, and a release agent layer are sequentially formed on the surface of ordinary paper made from wood pulp with a freeness of 350 to 500 ml CSF (see Patent Document 2). Furthermore, a release paper is known characterized by sequentially providing a sealing layer made of a water-soluble resin, an intermediate layer made of a water-soluble resin, and a release layer on at least one surface of a base paper using pulp with a beaten degree of 20 to 44°SR (see Patent Document 3). Furthermore, there is a known release paper characterized by forming a sealing layer on a water-dispersible paper substrate by coating an acrylate-based latex containing a copolymer of ethyl acrylate and butyl acrylate at a solid content of 0.5 to 10 g/ m² , and then forming a release layer on the sealing layer by coating a solvent-free silicone at a solid content of 0.3 to 3 g/ m² (see Patent Document 4). Japanese Patent Publication No. 2016-223036Japanese Patent Publication No. 2005-010513Japanese Patent Publication No. 2002-166504Japanese Patent Application Publication No. 06-305087 This figure schematically shows a cross-section of a release liner and a base paper for release liner according to one embodiment of the present invention. An embodiment of the present invention will be described in detail below with reference to Figure 1. However, the scope of the present invention is not limited to the release paper shown in Figure 1. As shown in Figure 1, the release paper base paper 1 of the present invention is a release paper base paper 1 formed by laminating a sealing layer 3 on at least one surface 2b of a base paper 2, wherein the sealing layer 3 is a resin layer formed from a sealing layer forming composition mainly composed of a water-based polyurethane resin. The base paper 2 used in the release paper base paper 1 of the present invention mainly consists of wood pulp fibers. As wood pulp fibers, chemical pulps such as softwood kraft pulp, hardwood kraft pulp, and sulfite pulp; mechanical pulps such as stone-ground pulp, thermomechanical pulp, and refiner-ground pulp; and recycled pulp obtained from newspapers, coated paper, fine paper, etc., can be appropriately blended and used. Furthermore, the base paper 2 may also contain non-wood pulps such as kenaf, hemp, and bamboo, as well as fiber materials other than cellulose fibers such as glass fibers and polyethylene fibers, as needed. During the papermaking process for base paper 2, internal additives such as sizing agents, paper strength enhancers, fixatives, yield enhancers, and dyes, as well as internal fillers such as talc, kaolin, titanium dioxide