JP7706359B2 - release paper - Google Patents

Description

The present invention relates to release paper, a method for producing release paper, a shaped object, and synthetic leather. More specifically, the present invention relates to release paper for forming a shaped object or synthetic leather with a fine, uniform uneven shape with few shape defects on the surface, a method for producing this release paper, and a shaped object and synthetic leather produced using this release paper.

Conventionally, synthetic leathers made mainly from vinyl chloride resins or polyurethane resins have been widely used. Such synthetic leathers are often produced using release paper. For example, to produce polyurethane leather, a paste-like polyurethane resin is applied to the surface of the surface resin layer of the release paper, and after drying and solidification, a fabric substrate is attached and peeled off from the release paper. If the release paper is given a squeezed pattern or uneven shape similar to that of natural leather, a good pattern can be imparted to the surface of the resulting synthetic leather. Alternatively, a pattern that does not imitate natural products, such as a geometric pattern, is also acceptable.

The release paper used in the manufacture of such synthetic leather is used to transfer the surface pattern onto the synthetic leather, and must have a surface condition suitable for shaping.

Among them, a release paper on which an optical interference pattern is formed by extremely fine irregularities has been disclosed (Patent Document 1).

In addition, a release paper for synthetic leather, which is made by bonding a paper base material with a surface resin layer, has been presented in which irregularities corresponding to the pattern to be formed on the surface of the synthetic leather are formed on the surface resin layer of the release paper, making the formed irregularities more uniform and closer to the intended design.

The device is explained below. The unevenness of the surface of the paper base material on the side of the surface resin layer affects the surface of the surface resin layer, causing unintended unevenness to appear on the surface. When the synthetic leather is shaped, the unevenness deteriorates the finish of the synthetic leather. As a countermeasure, a release paper has been disclosed in which the surface of the paper base material is smoothed and a surface resin layer is provided on the surface of the paper base material, so that the unevenness of the paper base material does not appear on the surface of the surface resin layer, and the pattern can be well shaped. (Patent Document 2)

Japanese Patent Application Publication No. 4-361671 JP 2006-2264 A

However, although the release paper of Patent Document 1 can form extremely fine irregularities, there is a problem in that the surface of the release paper lacks uniformity due to factors that arise after the release paper is manufactured.

In addition, in the release paper of Patent Document 2, a surface resin layer with good surface properties can be produced during the production of the release paper, but there is a problem in that the surface of the release paper lacks uniformity due to factors that arise after the production of the release paper.

The problems that arise after production in Patent Documents 1 and 2 occur during the process leading up to the production of synthetic leather, such as during transportation and storage of the release paper.

Figures 1 to 6 are diagrams explaining conventional release papers. As shown in Figure 1, after the paper base material and the resin layer are bonded together, the release paper 2 is wound into a roll 1 for transport or storage. During transport or storage, the roll core 3 is often placed so that it is horizontal to the ground. The surface on which the roll 1 is placed is a floor surface, a pallet surface, a truck bed (hereinafter referred to as the floor surface, etc.), etc., and since it is placed on a flat surface, a stopper (not shown) is often installed so that the outer periphery of the roll comes into contact with the floor surface, etc. to prevent it from rolling.

When the roll 1 is placed on a floor surface, etc., the contact area with the floor surface, etc. is almost linear because the roll 1 is cylindrical, and the contact area is not large. The weight of the roll 1 is applied to the contact point between the roll 1 and the floor surface, etc., or near the contact point, but because the contact area is small, the pressure applied to the contact point is large.

In addition, when a stopper is installed to prevent the roll 1 from rolling, a pressing force is applied to the contact point between the stopper and the roll.

In addition, vibrations and shocks occur during transportation, and pressure is applied to the contact points of roll 1.

In addition, shocks also occur when loading and unloading. At such times, unexpected external forces may be applied, such as when the forks of a forklift hit roll 1.

In addition, because tension is applied to the web of release paper 2 while it is being wound, the web shrinks after the roll 1 is completed, and this shrinkage force becomes a pressing force in the direction of the winding core 3. This is called "tightening of the winding," and the pressing force generated here becomes a pressing force in the cross-sectional direction of the release paper 2.

Although each of these pressure forces affects roll 1 individually, they can occur simultaneously, in which case the pressure forces add up to become even greater.

Figure 2 shows an enlarged view of part A in Figure 1. Part A is the area near the floor surface of roll 1. Figure 3 shows an enlarged view of part B in Figure 2. Part B is an enlarged cross-sectional view of the area where surface 25 of paper substrate 21 of release paper 2 and surface 23 of surface resin layer 22 of release paper 2 are in contact.

In the conventional paper base material 21, the fibers of the paper base material 21 are visible on the surface 25, and the fibers cause unevenness. The fibers cause protrusions 26 on the surface 25 of the paper base material 21, and the protrusions 26 are in contact with the surface 23 of the surface resin layer 22. When a strong pressing force is applied to the contact portion 27 between the surface 25 of the paper base material 21 of the release paper 2 and the surface 23 of the surface resin layer 22 of the release paper 2 in a direction perpendicular to the contact portion, the protrusions 26 sink into the surface 23 of the surface resin layer 22 as shown in FIG. 4, forming recesses 28. When the release paper 2 is unwound from the roll 1, the surface 25 of the paper base material 21 and the surface 23 of the surface resin layer 22 are peeled off, and the defect of the recess 28 appears on the surface 23 of the surface resin layer 22 of the release paper 2 as shown in FIG. 5. The recesses 28 are the protrusions 26 transferred from the surface 25 of the paper base material 21, and this phenomenon is called offset.

The recesses 28 impair the uniformity of the pattern of the shaping portion 24 on the surface 23 of the surface resin layer 22. A cross-sectional view of synthetic leather 6 manufactured using such release paper is shown in Figure 6. Protrusions 64 appear on the surface of the shaping resin layer 61, resulting in defects. A detailed explanation of synthetic leather will be given later.

The above explanation was about rolls, but similar problems occur with sheets. When sheets are stacked, a large weight is placed on the bottom layer, and the sheets may also be subjected to pressure when hit by other objects. In such cases, pressure is also applied in the vertical direction to the surface of the release paper 2, and as with the rolls described above, this can impair the uniformity of the pattern in the shaped portion 24 on the surface 23 of the surface resin layer 22 of the release paper 2.

The present invention was made in consideration of the above circumstances, and aims to provide a release paper that can maintain its design without compromising the uniformity of the surface pattern on the surface resin layer of the release paper, even if unexpected external forces or internal forces such as tightening of the roll occur during transportation or storage after production of the release paper.

The release paper of the present invention, which is intended to solve the above problems, is characterized by comprising a paper base material, a surface resin layer provided on one side of the paper base material and having an uneven surface, and a smoothing layer provided on the other side of the paper base material and smoothing the surface of the paper base material.

The method for producing the release paper of the present invention is characterized by comprising the steps of preparing an original plate having a plate surface with irregularities corresponding to the irregularities formed in the surface resin layer, forming the surface resin layer on one side of the paper base material, forming a smoothing layer on the other side of the paper base material, forming a shaped portion on the surface of the surface resin layer, overlapping the surface of the surface resin layer with the plate surface of the original plate to form irregularities, and peeling the original plate from the release paper.

According to the present invention, the surface of the paper base material of the release paper is smoothed, and even if the surface of the paper base material of the release paper and the surface of the surface resin layer are pressed together during storage or transportation in a roll, a release paper can be provided in which the uniformity and design of the pattern on the surface of the surface resin layer is not impaired.

FIG. 2 is a perspective view of a roll of release paper. This is an enlarged view of part A in the A-A cross section of the release paper roll. FIG. 3 is an enlarged view of part B of FIG. 2 of the conventional release liner. 3 is an enlarged view of part B in FIG. 2 when a strong pressing force is generated in the core direction of a conventional release paper roll. FIG. 1 is a cross-sectional view of a surface resin layer of a conventional release paper when the release paper is unwound from a roll to which it has been strongly pressed. FIG. 1 is a cross-sectional view of synthetic leather produced using a conventional release paper and having defects on its surface. FIG. 2 is a cross-sectional view of the release liner of the present invention. FIG. 2 is a cross-sectional view of a shaped object and synthetic leather of the present invention. FIG. 2 is an explanatory diagram of the method for producing the release paper of the present invention. FIG. 3 is an enlarged view of part B of FIG. 2 of the release liner of the present invention. 3 is an enlarged view of part B in FIG. 2 when a strong pressing force is generated in the core direction of the roll of release paper of the present invention. 1 is a diagram illustrating a method for producing a synthetic leather according to the present invention. FIG. 1 is an enlarged photograph of the surface of a release liner having a good synthetic resin layer surface (sample S1). 1 is an enlarged photograph of the surface of the synthetic resin layer taken after the surface of the paper base material of a conventional release liner and the surface of the synthetic resin layer were pressed together at 100 kN/m (sample S2). 1 is an enlarged photograph of the surface of the synthetic resin layer taken after the surface of the paper base material of the release liner of Example 1 of the present invention and the surface of the synthetic resin layer were pressed together at 100 kN/m (sample S3). 1 is an enlarged photograph of the surface of the synthetic resin layer taken after the surface of the paper base material of the release liner of Example 2 of the present invention and the surface of the synthetic resin layer were pressed together at 100 kN/m (sample S4). 1 is an enlarged photograph of the surface of the synthetic resin layer taken after the surface of the paper base material of the release liner of Example 3 of the present invention and the surface of the synthetic resin layer were pressed together at 100 kN/m (sample S5). 1 is an enlarged photograph of the surface of the synthetic resin layer taken after the surface of the paper base material of a conventional release liner and the surface of the synthetic resin layer were pressed together at 200 kN/m (sample S6). 1 is an enlarged photograph of the surface of the synthetic resin layer taken after the surface of the paper base material and the surface of the synthetic resin layer of Example 1 of the present invention were pressed together at 200 kN/m (sample S7). 1 is an enlarged photograph of the surface of the synthetic resin layer taken after the surface of the paper base material and the surface of the synthetic resin layer of Example 2 of the present invention were pressed together at 200 kN/m (sample S8). 1 is an enlarged photograph of the surface of the synthetic resin layer taken after the surface of the paper base material and the surface of the synthetic resin layer of Example 3 of the present invention were pressed together at 200 kN/m (sample S9).

The present invention will be described below with reference to the drawings. However, the present invention is not limited to these specifically exemplified forms or the various specifically described structures.

In addition, in each figure, the size and proportions of components may be changed or exaggerated to make them easier to understand. Also, for ease of viewing, parts that are not necessary for the explanation or repeated symbols may be omitted.

The release paper of the present invention is mainly used for producing synthetic leather, but can also be used for producing surface materials for shoes, bags, sofas, chairs, vehicle seats, etc., interior building materials such as boxes, packaging containers, wallpaper and flooring, home appliances such as refrigerators and television receivers, and surface decoration materials for automobile parts such as dashboards and interior door panels, etc. These articles are collectively called the shaped object, and in the following explanation, synthetic leather will be used as a representative example.
<Release paper>
The release paper of the present invention is a sheet for forming a design irregularity in the resin layer of synthetic leather. Recently, synthetic leather is required to have a quality closer to that of natural leather, and reproduction of finer irregularities is required. In addition, even in artificial patterns that are not imitations of natural leather, design due to finer irregularities and uniformity of the pattern are required to enhance the design. In addition, a high gloss mirror finish is also required.

Figure 7 is a cross-sectional view of the release paper 4 of the present invention, in which a surface resin layer 42 is provided on one side of a paper substrate 41, and a shaping section 44 is provided on the surface 43 of the surface resin layer 42 for shaping the shaped resin layer of the synthetic leather.

The other surface of the paper base material 41 is provided with a smoothing layer 45.

Here, the shaping portion 44 is formed by shaping the shaping projections 46 and shaping recesses 47 into the shaping target resin layer of the synthetic leather to form projections and recesses on the surface. The shaping portion 44 can be formed by embossing using a master plate having a shape corresponding to the projections and recesses of the shaping portion 44.

In addition, an anchor coat layer (not shown) may be formed between the paper base material 41 and the surface resin layer 42 to improve adhesion between the layers. Furthermore, an intermediate layer may be formed between the paper base material 41 and the surface resin layer 42 to improve smoothness, seal the gap, and improve adhesion.

As described above, the release paper 4 is used as a shaping mold for forming the shaped portion 63 on the surface of the shaped resin layer 61 that constitutes the synthetic leather 6, and since it has a shaped portion 44 that corresponds to the shaped portion 63 of the synthetic leather 6, it is possible to easily produce synthetic leather 6 in which a uniform uneven shape is formed in the shaped resin layer 61 of the synthetic leather 6.

The components of the release paper 4 will be described below in order.
<Paper base material>
The paper base material 41 serves as a support for the release paper 4 .

The pulp of the paper base material 41 is preferably a mixture of softwood pulp (N material) and hardwood pulp (L material) in order to obtain strength and smoothness that can withstand the process of forming the shaped portion 44 and the process of producing synthetic leather. In this case, the mixing ratio of hardwood pulp (L material) is preferably 50% to 90% in order to balance strength and smoothness. The paper base material 41 needs to be neutral paper in order to obtain sufficient heat resistance of the release paper 4, and neutral paper sized using alkyl ketene dimer as a sizing agent is preferable.

The basis weight of the paper base material 41 is preferably 100 g/ ^m2 to 200 g/ ^m2 in terms of strength, ease of processing into synthetic leather, durability of the release paper for repeated use, and suitability for embossing. If the basis weight is less than 100 g/ ^m2 , curling or waviness will occur during the production of synthetic leather, and the paper will be prone to breaking on the production line. Conversely, if the basis weight is more than 200 g/ ^m2 , the suitability for embossing will be poor, and the release paper will become thicker, resulting in a larger roll diameter, which will reduce work efficiency and increase costs.

The thickness of the paper base material 41 is from 100 μm to 900 μm, and preferably from 150 μm to 600 μm.
<Smoothing layer>
The smoothing layer 45 is provided on at least the surface (the surface opposite to the surface resin layer 42) of the paper base material 41, and serves to smooth the rough surface of the paper base material 41. The smoothing layer 45 is made of, for example, a clay coat layer.

The clay coat paint composition is made of, for example, clay, and any clay generally called clay or clay can be used without any particular limitation. Examples of clay that can be used include kaolin, talc, bentonite, smectite, vermiculite, mica, chlorite, woodbush clay, gairome clay, halloysite, and mica. As for clay, talc has a low hardness (Mohs hardness 1) and excellent heat resistance, so it can improve heat resistance and dimensional stability during embossing. Furthermore, the high hardness of the smoothing layer 45 can prevent deformation and scratches due to external forces, and the smoothness of the smoothing layer 45 can be maintained.

In addition, the coating composition for the clay coat layer preferably contains, in addition to clay, a pigment such as calcium carbonate, titanium dioxide, amorphous silica, expandable barium sulfate, or satin white. By using calcium carbonate or titanium dioxide as a pigment, the smoothness of the surface of the clay coat layer can be increased. Furthermore, calcium carbonate is preferably used because it is inexpensive.

The coating liquid for applying the clay coat layer contains the above-mentioned clay in a solvent, a binder, and, if necessary, other pigments and additives. As the solvent, water, alcohol, etc. are usually used. As the binder, a latex-based binder (e.g., styrene butadiene latex, acrylic latex, vinyl acetate latex), a water-soluble binder (e.g., starch (modified starch, oxidized starch, hydroxyethyl etherified starch, phosphate esterified starch), polyvinyl alcohol, casein, etc.) is usually used. As the additives, a pigment dispersant, a defoamer, an antifoaming agent, a viscosity adjuster, a lubricant, a water-resistant agent, a water-retaining agent, etc. are used.

The method for applying the clay coating layer is not particularly limited, but methods such as air knife coating, blade coating, and short dwell coating can be used.

The coating amount and thickness of the clay coat layer are not particularly limited, but the basis weight after drying is usually 5 g/ ^m2 to 40 g/ ^m2 , and preferably 10 g/ ^m2 to 40 g/ ^m2 . If the basis weight after drying is less than 5 g/ ^m2 , the smoothness may be inferior. If the basis weight after drying exceeds 40 g/ ^m2 , there is a possibility of a decrease in adhesion due to cohesive failure of the clay coat layer, and the cost performance is inferior.

Instead of the clay coat layer, a cast coat layer with greater smoothness can also be used.

The manufacturing method of cast-coated paper having a cast-coated layer is roughly classified into a wet method (direct method), a gelation method (solidification method), and a rewetting method (indirect method) according to the processing method for obtaining the glossy finish of the cast-coated layer. That is, the wet method is a method in which the cast-coated layer is pressed against a heated metal mirror drum while in a wet state, dried, and finished to a glossy finish. The gelation method is a method in which the cast-coated layer in a wet state is passed through a solidification liquid to gel it, and then pressed against a heated metal mirror drum, dried, and finished to a glossy finish. The rewetting method is a method in which the cast-coated layer in a wet state is once dried, and then rewetted with a rewetting liquid, and after it is plasticized, pressed against a heated metal mirror drum, dried, and finished to a glossy finish.
Each manufacturing method is selected appropriately depending on the required specifications of the cast-coated paper.

In addition, the smoothing layer 45 may be made of a polyolefin resin instead of a clay coat layer and may be formed by extrusion coating on one side of the paper substrate. Furthermore, a film with a smooth surface, such as a polyethylene terephthalate film or a polypropylene film, may be dry laminated or extrusion laminated via an adhesive resin.

When using materials with relatively rough surfaces such as kraft paper or fine paper as the paper base material, the effect of improving the smoothness of the paper base material is significant.

By forming the smoothing layer 45 on the paper substrate 41, the arithmetic mean roughness Ra (Ra is the arithmetic mean roughness based on Japanese Industrial Standard JIS-B-0601-2001) of the surface 80 of the smoothing layer 45 is 2 μm or less when measured using a shape analysis laser microscope (Keyence VK-8710). Furthermore, if the arithmetic mean roughness Ra of the surface 80 of the smoothing layer 45 is less than 0.5 μm, the smoothness will be excessive, which will lead to increased costs. The arithmetic mean roughness Ra is the average of the values obtained by measuring an area of 1 mm square 10 times. The arithmetic mean roughness Ra described hereinafter is measured using the above-mentioned measuring device and method.

The thickness of the smoothing layer 45 is not particularly limited, but a thickness of 10 μm to 60 μm is preferable, as this provides an excellent balance between performance and cost.

The smoothing layer 45 is provided at least on the surface side of the paper base material 41 (the side opposite the surface resin layer 42), but may or may not be provided on the surface of the paper base material 41 facing the surface resin layer 42, and is selected appropriately depending on the intended use, etc.

The surface 80 of the smoothing layer 45 of the paper base material 41 has high smoothness, so the quality of the release paper 4 can be maintained during transportation and storage. The effect of this will be described later.

(Anchor coat layer)
An anchor coat layer (not shown) is provided on the adhesive surface between the paper base material 41 and the surface resin layer 42 as required, and has the function of increasing the adhesiveness between the paper base material 41 and the surface resin layer 42 .

The anchor coat layer can be formed, for example, by applying a water-soluble or water-dispersible emulsion or dispersion anchor coat agent.

Examples of the anchor coating agent include emulsions or dispersions of polypropylene, modified polyolefin, ethylene-vinyl acetate copolymer, polyethyleneimine, polybutadiene, polyurethane, and polyester resins, as well as polyvinyl chloride emulsions, urethane acrylic resin emulsions, silicon acrylic resin emulsions, vinyl acetate acrylic resin emulsions, acrylic resin emulsions, and rubber-based latexes such as styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, chloroprene latex, and polybutadiene latex, polyacrylic acid ester latex, polyvinylidene chloride latex, or carboxyl-modified products of these latexes. Examples of water-soluble anchor coating agents include aqueous solutions of polyvinyl alcohol, water-soluble ethylene-vinyl acetate copolymer, polyethylene oxide, water-soluble acrylic resin, water-soluble epoxy resin, water-soluble cellulose derivative, water-soluble polyester, water-soluble isocyanate, and water-soluble lignin derivative.

Among these, emulsions or dispersions of polypropylene-based or modified polyolefin-based resins are preferred because they can further increase the lamination strength of the polypropylene-based resin layer to the paper and also have excellent heat resistance.

The anchor coating agent can be applied by, for example, gravure coating, reverse roll coating, knife coating, kiss coating, etc., and the coating amount after drying is preferably 0.1 g/m ² to 5 g/m ² .

<Surface resin layer>
The surface resin layer 42 has a shaping portion 44 formed on its surface, which functions as a shaping mold when producing synthetic leather.

The additives contained in the surface resin layer 42 are not particularly limited, but may include, for example, a mixture with inorganic or organic fine particles.

Examples of the resin for the surface resin layer 42 include alkyd resins, melamine resins such as methylol melamine resins and methoxymethylol melamine resins, silicone resins, acrylic resins, and other thermosetting or radiation curing resins (including ultraviolet curing resins, etc.). In addition, thermoplastic resins such as polyolefin resins such as polymethylpentene, polypropylene, and polyethylene can also be used as the resin for the surface resin layer 42. These resins may be used alone or in combination of two or more types, taking into account the shaping properties with the resin of the shaping resin layer 61 of the synthetic leather.

In addition, the surface resin layer 42 may further contain dispersants, viscosity adjusters, colorants, antistatic agents, etc., as necessary.

For example, from the viewpoint of durability, the thickness of the surface resin layer 42 is preferably 10 μm or more, and more preferably 20 μm or more. Also, from the viewpoint of material costs, the thickness of the surface resin layer 42 is preferably 100 μm or less, and more preferably 50 μm or less. In summary, the thickness of the surface resin layer 42 is preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 50 μm or less.

It is preferable that the thickness of the surface resin layer 42 be set appropriately in relation to the shape and size of the shaping portion 44.

Methods for applying the surface resin layer 42 include extrusion coating, roll coating, reverse roll coating, microbar coating, bar coating, knife coating, gravure coating, etc.

Alternatively, a method of laminating prepared films may be used. Examples of such methods include extrusion lamination, dry lamination, and wet lamination.

As a method for forming a smooth surface before the uneven processing of the surface 43 of the surface resin layer 42, for example, the paper base material 41 and the surface resin layer 42 are laminated by melt extrusion, and then the surface resin layer 42 is passed continuously between a mirror-finished roll 72 with a mirror-finished surface and a pressing roll 71 so that the surface resin layer 42 is in contact with the mirror-finished roll 72, thereby improving the smoothness of the surface.

As shown in FIG. 7, a shaping portion 44 is formed on the surface of the surface resin layer 42. The shaping portion 44 is an unevenness that functions as a shaping mold for forming a shaping portion 63 on the surface of the shaping resin layer 61 of the synthetic leather 6. In other words, the shaping portion 44 is an unevenness that corresponds to the shaping portion 63 of the shaping resin layer 61 of the synthetic leather 6. The shaping resin layer 61 of the synthetic leather 6, which is the target to be shaped by the shaping portion 44, can be embossed to form unevenness on its surface.

As explained above, the release paper 4 according to the present invention can be preferably used for producing the synthetic leather 6 having the shaping-target resin layer 61 having irregularities formed on its surface.
<Shaped object and synthetic leather>
As shown in FIG. 8, the shaped object 5 in the present invention is a sheet-like article in which a surface pattern of a shaped portion 53 is formed in a shaped resin layer 51 using the release paper 4 of the present invention.

The object to be shaped may be a continuous sheet in roll form or a leaf sheet. A leaf sheet object to be shaped may be made from a leaf sheet of the object to be shaped, or may be obtained by cutting a continuous sheet of the object to be shaped.

Figure 8 is a cross-sectional view showing an example of a shaped object 5. The shaped object 5 comprises a shaped resin layer 51 and a base material layer 52, which are laminated together. A shaped portion 53 having design properties is provided on the surface of the shaped resin layer 51.

The thickness of the shaped resin layer 51 is not particularly limited and varies depending on the application and the depth of the irregularities.

The base layer 52 of the object 5 is a layer laminated on the side opposite the side on which the unevenness is formed of the resin layer 51 to be shaped, and supports the resin layer 51 to be shaped.

The thickness of the base layer 52 is not particularly limited as long as it is thick enough to support the resin layer 51 to be shaped, but can be in the range of 25 μm or more and 500 μm or less, for example.

The material of the base layer 52 may be selected from materials that support the shaped resin layer 51 and are appropriate for the application of the shaped object 5, and may be selected appropriately according to the type of resin and application from materials generally used for synthetic leather or the base material or base fabric of synthetic leather, such as natural fibers such as cotton, linen, silk, and wool, regenerated or semi-synthetic fibers such as rayon and acetate, synthetic fibers such as polyamide, polyester, polyacrylonitrile, polyvinyl alcohol, and polyolefin, woven fabric, nonwoven fabric, mesh fabric, and other fabrics (also called base fabrics) made of fibers such as glass fiber, paper, resin films made of polyester or polyolefin resins, metal plates or metal foils, glass plates, and glass woven fabrics.

The resin composition constituting the shaped resin layer 51 can be made of various thermoplastic resins, thermosetting resins, ionizing radiation curable resins such as ultraviolet rays or electron beams, etc., and can be appropriately selected depending on the application, manufacturing conditions, etc.

Specific applications of the shaped object include, for example, surface materials for synthetic leather products, shoes, bags, sofas, chairs, vehicle seats, etc., interior building materials such as boxes, packaging containers, wallpaper and flooring, home appliances such as refrigerators and television receivers, and surface decoration materials for automobile parts such as dashboards and interior door panels.

Among the uses of the above-mentioned shaped objects, one area with relatively high demand is synthetic leather, which will be explained below.

As shown in Figure 8, the synthetic leather 6 according to the present invention is characterized by comprising a substrate 62 and a shaped resin layer 61 in which a shaped portion 63 is formed over the entire surface of one side of the substrate 62. Note that Figure 8 has the same layer structure as the shaped object 5, so the same drawing will be used for the explanation, but the reference numerals will be interpreted as those corresponding to the synthetic leather.

The components of synthetic leather 6 are explained below in order.

<Base material>
The substrate 62 constitutes the synthetic leather 6, and has a shaped resin layer 61 on one side. The substrate 62 is not particularly limited, and may be a fabric (base fabric) used in known synthetic leathers, such as natural fabric, nonwoven fabric, or artificial fabric. The substrate may also be a resin sheet other than fabric, or a structure covered with the resin sheet. Examples of resin materials constituting such a resin sheet include vinyl chloride, urethane resin, unsaturated polyester resin, acrylic-urethane resin, acrylic acid ester resin, acrylamide resin, nitrocellulose resin, polystyrene resin, alkyd resin, and phenolic resin.

When the substrate 62 is in the form of a sheet, its thickness can be set appropriately depending on the use to which the synthetic leather is to be applied. For example, the lower limit is preferably 100 μm or more, and more preferably 500 μm or more, from the viewpoints of durability, touch, etc. The upper limit is preferably 20 mm or less, and more preferably 10 mm or less, from the viewpoints of handleability, etc.

When the substrate 62 is in the form of a roll, the thickness is preferably 5 mm or less, more preferably 2 mm or less, from the viewpoint of ease of winding. As with the case of a sheet, the lower limit is preferably 100 μm or more, more preferably 500 μm or more.

<Shaped resin layer>
The shaping-receiving resin layer 61 constitutes the synthetic leather 6 together with the above-mentioned substrate, and is formed on one surface of the substrate 62. On the surface of the shaping-receiving resin layer 61, a shaping-receiving portion 63 is formed.

The shaping resin layer 61 is mainly composed of a resin material. Examples of resin materials for synthetic leather include thermoplastic resins, thermosetting resins, and radiation-curable resins. Specifically, vinyl chloride resins, urethane resins, and the like can be preferably used.

The shaped resin layer 61 may optionally contain one or more selected from a plasticizer, a foaming agent, a stabilizer, a colorant, etc.

The color of the resin layer 61 to be shaped is not particularly limited, and can be a desired color such as red or black using a coloring agent. The coloring agent can be a pigment or a dye, and is not particularly limited. However, from the viewpoint of coloring the tip of the unevenness, it is more preferable to use a dye that does not have such a possibility than to use a pigment that has a large particle size and may not penetrate to the tip of the unevenness.

The thickness of the shaped resin layer 61 can be set appropriately depending on the intended use of the synthetic leather. The lower limit of the thickness of the shaped resin layer 61 is preferably 10 μm, more preferably 30 μm, from the viewpoint of durability. Similarly, the upper limit is preferably 200 μm, more preferably 150 μm, so as not to impair the texture of the synthetic leather.

In summary, the thickness of the shaped resin layer 61 is preferably 10 μm or more and 200 μm or less, and more preferably 30 μm or more and 150 μm or less.

The shaping-receiving resin layer 61 may be formed by directly applying it onto the substrate 62, or the substrate and the resin layer may be bonded together via an adhesive layer or the like.
<Production method of release paper>
A method for producing the release paper 4 according to the present invention for forming irregularities in the shaped resin layer 61 of the synthetic leather 6 will be described.

In detail, as shown in FIG. 9, the method for producing the release paper 4 according to the present invention includes the steps of preparing an original plate 74 on which a plate surface 75 having projections and recesses corresponding to the shaped portion 63 to be formed in the shaped resin layer 61 of the synthetic leather 6 is formed, preparing a laminated sheet 7 including a paper base material 41 and a surface resin layer 42 to be formed on the paper base material 41, forming a smooth surface on the surface 43 of the surface resin layer 42 by processing using a mirror-finishing roll 72, overlapping the smooth surface of the laminated sheet 7 with the plate surface 75 of the original plate 74 to form the projections and recesses of the plate surface 75 on the surface 43 of the surface resin layer 42, and peeling the laminated sheet 7 from the original plate 74.

<Preparation of the master plate>
First, an original plate 74 is prepared on which a plate surface 75 having projections and recesses corresponding to the shaped portion 63 to be formed in the shaped resin layer 61 of the synthetic leather 6 is formed. The plate surface 75 has projections and recesses corresponding to the shaped portion 63 to be shaped on the surface of the synthetic leather 6. In other words, by using the release paper 4 manufactured by this method, a synthetic leather 6 having projections and recesses corresponding to the projection and recess structure of the plate surface 75 can be manufactured. The original plate 74 is not particularly limited as long as it has a strength capable of forming the shaped portion 44 on the release paper 4 and has a strength capable of withstanding the temperature conditions, pressure conditions, and the like of each process during the formation process. Examples of materials that can be used for the original plate 74 include stainless steel plate, plated iron, plated copper, and the like.

The means for producing the uneven structure on the plate surface 75 of the master 74 is not particularly limited, but for example, the uneven structure can be formed on the material that will become the master 74 by using means such as electrolytic plating, electroless plating, anodizing, and etching.

<Preparation of laminated sheet>
Furthermore, a laminate sheet 7 is prepared. The laminate sheet 7 is a sheet including a paper base material 41, a surface resin layer 42 on one surface of the paper base material 41, on which a concave-convex shape is to be formed by a plate surface 75, and a smoothing layer 45 on the other surface of the paper base material 41.

The paper base material 41 and the surface resin layer 42 may be bonded directly to each other, or may be bonded via an intermediate layer. Examples of intermediate layers include a layer for improving the bonding strength, a layer for smoothing the surface of the paper base material, and a layer for improving the shapeability of the surface resin layer.

The resin 73 is extruded from the extruder 70 and layered on the paper substrate 41 to prepare the laminated sheet 7.

The surface resin layer 42 may be a multi-layered layer of different resins. As an example, the layer structure of the release paper is as follows:
[Smoothing layer 45th side]/Paper base material/Resin A/Resin B/[Shaping part 44th side]
In the composition of the above, the physical properties required for resin A and resin B may differ. Resin B is often required to be heat resistant since the temperature rises during the production of synthetic leather, while resin A is often required to be adhesive to both the paper substrate and resin B. In addition, since resin A does not require the same level of heat resistance as resin B, a cheaper resin can be used to reduce costs.

The surface resin layer 42 may be multi-layered by extruding the resin 73 in FIG. 9 together from the extruder 70 (not shown). Alternatively, a multi-layer resin film may be prepared and laminated. Alternatively, resin A may be melt-extruded as an adhesive resin, and resin B may be laminated as a film.

Various known methods can be used for lamination, such as dry lamination and extrusion lamination.

<Process for forming smooth surface>
A smooth surface is formed on the surface 43 of the surface resin layer 42 of the laminate sheet 7 by processing using a mirror finish roll 72. That is, the laminate sheet 7 is pressed between a pressing roll 71 located immediately below an extruder 70 and the mirror finish roll 72 to laminate the surface resin layer 42 onto the surface of the paper base material 41, thereby forming a smooth surface.

The mirror-finished roll 72 used in this case may be a mirror-type roll that has been chrome-plated and then traverse-ground or polished, or a semi-mirror-type roll that has been wet-blasted or dry-blasted. The mirror-finished roll 72 may also be an ultra-fine matte-type roll, so long as the surface of the roll is smoother than the surface 80 of the smoothing layer 45 of the paper substrate 41. By using the mirror-finished roll 72, the smoothness of the surface resin layer 42 can be improved.

The surface of the mirror-finished roll 72 need not be mirror-like, but may have fine irregularities, and a background pattern may be created. It is desirable that the size of the irregularities of this background pattern be smaller than the irregularities formed in the subsequent shaping process, and the size is appropriately set depending on the design of the release paper 4.

<Shaping process>
Next, the surface resin layer 42 of the laminated sheet 7 and the plate surface 75 of the original plate 74 are overlapped and pressed between the pressing roll 76 and the original plate 74 to form the unevenness of the plate surface 75 on the surface 43 of the surface resin layer 42. At this time, the original plate 74 is overlapped on the laminated sheet 7 so that the surface resin layer 42 of the laminated sheet 7 and at least a part of the plate surface 75 of the original plate 74 are in contact with each other. As a result, the unevenness formed on the plate surface 75 of the original plate 74 is formed on the surface resin layer 42 of the laminated sheet 7, and the release paper 4 is formed. The shaping portion 44 of the release paper 4 is an inverted shape of the unevenness of the plate surface 75. For this shaping process, a shaping means can be appropriately selected in consideration of the material of the surface resin layer 42, etc. The original plate 74 having the plate surface 75 can be in the form of a cylinder (roll) or a plate. The material of the pressing roll 76 may be a material that is easily deformed, such as a paper roll, rubber, elastomer, etc., or a material that is less easily deformed, such as metal, ceramic, or hard plastic, and is selected appropriately depending on the layer structure of the release paper 4, the type of resin, and the application.

<Peeling process>
Next, the master 74 is peeled off from the laminate sheet 7. By this peeling step, the release paper 4 having the shaped portion 44 formed on the surface resin layer 42 can be obtained.

Each step in the above-mentioned method for producing the release paper 4 may include a heating step, a cooling step, a drying step, etc., as necessary. Furthermore, the method for producing the release paper 4 according to the present invention is not limited to the above-mentioned method.

<Transportation and storage of release paper>
After the peeling process, the release paper 4 is transported and stored in rolls or sheets. Rolls are often used because of ease of transportation and the wide range of processing options available in the subsequent processes. The ease of transportation means that while transporting sheets entails the risk of the load falling apart, rolls are less likely to fall apart. The wide range of processing options means that the rolls can be supplied to a processing machine in the subsequent process as is, or the rolls can be cut to any size.

A roll 1 of the release paper 4 of the present invention is shown in Figure 1. This figure was also used to explain the conventional release paper 2 in the section on problems to be solved by the invention, but Figure 2 should also be interpreted with the reference numerals for the release paper 4 of the present invention. In addition, the conditions for transporting and storing the roll 1 of the release paper 4 of the present invention are the same as those for the conventional release paper 2, and as they have already been explained, they will not be repeated here.

Figure 1 shows a roll 1 of release paper 4 according to the present invention, and an enlarged view of part A in Figure 1 is shown in Figure 2. Part A is the part near the floor surface of roll 1. Furthermore, an enlarged view of part B in Figure 2 is shown in Figure 10. The surface 80 of the smoothing layer 45 of the paper base material 41 of the release paper 4 is in contact with the surface 43 of the surface resin layer 42 of the release paper 4. The surface 43 of the surface resin layer 42 has a shaped portion 44 that is a pattern made of projections and recesses.

As shown in FIG. 7, in the release paper 4 of the present invention, the paper base material 41 of the release paper 4 has the convex portions 49 caused by the paper fibers of the paper base material 41 shielded by the smoothing layer 45 and cannot be seen from the outside. In addition, the smoothing is achieved by the smoothing layer 45, and the surface 80 of the smoothing layer 45 has fewer convex portions.

Figure 10 shows the contact area 48 between the surface 80 of the smoothing layer 45 of the paper base material 41 and the surface 43 of the surface resin layer 42 when the release paper 4 is wound into a roll 1 and placed on a floor surface or the like. The contact area 48 is exaggerated in Figure 10 to make it look like there is a gap, but in reality there is almost no gap and the two are considered to be in almost contact, but not in close contact.

When a pressing force is applied in the direction of the core, the contact portion 48 is crushed as shown in FIG. 11, and the surface 80 of the smoothing layer 45 of the paper base material 41 and the surface 43 of the surface resin layer 42 come into close contact. Because the paper base material 41 of the release paper 4 of the present invention has a smoothing layer 45, the convex portion 49 caused by the fibers of the paper base material is not exposed, and therefore no damage occurs to the surface 43 of the surface resin layer 42.

The pressing force referred to here includes pressing forces due to the weight of the release paper, contact with a stopper, contact with the forks of a forklift, tightening of the roll, etc., and there is a possibility that the above pressing forces may be combined to generate even greater pressing forces.

The size and weight of a typical release paper roll is approximately 1,200 mm wide, 600 mm in outer diameter, and 400 kg in weight, and the roll's own weight exerts a large compressive force on the contact area between the outer periphery of the roll and the floor surface, etc.

As described above, in order to prevent defects from appearing in the shaped portion 44 of the surface resin layer 42 even when a pressing force is applied to the contact point between the surface 80 of the smoothing layer 45 of the paper base material 41 and the surface 43 of the surface resin layer 42, it is desirable that the smoothness, i.e., the surface roughness, of the surface 80 of the smoothing layer 45 of the paper base material 41 be within the following numerical range: When measured using a shape analysis laser microscope (Keyence VK-8710), the arithmetic mean roughness Ra (Ra is the arithmetic mean roughness based on Japanese Industrial Standards JIS-B-0601-2001) is 0.5 to 2.0 μm, more preferably 0.6 to 1.5 μm.
<Manufacturing method of synthetic leather>
The synthetic leather 6 is manufactured in the following manner.

The process includes the steps of preparing a laminated sheet 7 having a base material 62 and a shaped resin layer 61 provided on at least one surface of the base material 62, preparing a release paper 4 for forming irregularities in the shaped resin layer 61, overlapping the shaped resin layer 61 of the laminated sheet 7 with the surface resin layer 42 of the release paper 4, and peeling the overlapped release paper 4 from the laminated sheet 7 to form a shaped portion 63 on the surface of the shaped resin layer 61 of the laminated sheet 7.

First, a laminate sheet 7 and a release paper 4 are prepared. The laminate sheet 7 has a resin layer 61 formed on a substrate 62. The resin layer 61 is a resin layer before the unevenness is provided.

Next, the prepared resin layer 61 to be shaped of the laminated sheet 7 is superimposed on the surface resin layer 42 of the release paper 4.

Then, the overlapped release paper 4 is peeled off from the laminated sheet 7, and a shaped portion 63 is formed on the surface of the shaped resin layer 61 of the laminated sheet 7. That is, the shaped portion 44 of the release paper 4 is shaped into the shaped resin layer 61, forming an inverted unevenness on the surface of the shaped resin layer 61.

The surface resin layer 42 of the release paper 4 equipped with the shaping portion 44 is superimposed on the shaping-receiving resin layer 61 of the laminated sheet 7, and then a process for shaping the shaping-receiving resin layer 61 is carried out. Such a process is not particularly limited, and can be carried out taking into consideration the material of the resin layer, etc. Examples of such a process include a thermal embossing process in which heat is applied, a chill roll embossing process in which a resin softened by heat is pressed with a cooled roll, a process in which the resin is hardened by ultraviolet light to harden the shaping shape, and a process in which the resin is hardened by electron beams to harden the shaping shape.

Among these, thermal embossing, which involves the application of heat, is preferred because it can smooth out unevenness caused by the texture of the paper base material.

Depending on the material of the resin layer 61 to be shaped of the laminated sheet 7, for example, if a polyvinyl resin is used, a paste coating method can be used, and if a urethane resin is used, a dry process can be used. There are no particular limitations on the processing conditions such as temperature and pressure, and they can be set appropriately depending on the processing employed and the type of resin contained in the resin layer.

12, by peeling off the release paper 4, it is possible to obtain synthetic leather 6 having a shaping target portion 63 formed on the surface of the shaping target resin layer 61. There are no particular limitations on the various conditions such as the peeling speed and temperature during peeling of the release paper 4, and on the peeling means.
<Release paper for shaped object and manufacturing method for shaped object>
The release paper of the present invention can be applied to objects other than synthetic leather. The method for producing the release paper for objects is the same as that for synthetic leather.

In the manufacturing method of the shaped object, the resin layer to be shaped, materials, etc. are appropriately selected according to the application of the shaped object, and the processing method and processing conditions are also appropriately selected.

The present invention will be explained in more detail with reference to examples.

<Preparation of release paper>
Example 1
As the paper substrate, cast-coated paper (basis weight 164 g/m ² , cast-coated layer 10 μm to 40 μm, OK process release paper, manufactured by Oji Paper Co., Ltd.) was prepared.

The paper surface opposite the cast coat layer of this paper substrate was subjected to corona treatment, and a first polypropylene resin (polyethylene melt blend, manufactured by SunAllomer) was extruded from the first extruder of a co-extruder at 310°C as a resin layer, and a second polypropylene resin (homopolypropylene, manufactured by SunAllomer) was extruded on top of it from the second extruder of the co-extruder at 305°C and a line speed of 80 m/min to obtain a laminated sheet. The first polypropylene resin has properties that improve the adhesion between the paper substrate and the second polypropylene resin, and the second polypropylene resin has heat resistance. By using these resins in multiple layers, a release paper with a good balance between interlayer adhesion and heat resistance was produced.

Then, immediately afterwards, the surface of this laminated sheet was extrusion coated with a mirror-finished roll to smooth the surface of a 30 μm-thick resin layer, obtaining a surface resin layer.

The layer structure is as follows:
[Cast coat layer]/cast coat paper (basis weight 164 g/m ² )/first polypropylene resin layer (15 μm)/second polypropylene resin layer (15 μm)/[shape-imparting surface]
It is.

In order to make it easier to confirm the effects of the present invention, the shaped surface is given a mirror finish using the mirror finish roll, and no unevenness is created by embossing.

The arithmetic mean roughness Ra of the surface of the cast coat layer on the paper substrate was 0.65 μm.

Example 2
Paper with a clay-coated layer (basis weight 174.4 g/ ^m2 Ultra Satin Kinto, manufactured by Oji Paper Co., Ltd.) was used instead of the paper with a cast-coated layer used in Example 1. The other processing methods and materials were the same as those in Example 1.

The arithmetic mean roughness Ra of the paper substrate surface was 1.32 μm.

Example 3
Paper having a clay-coated layer (basis weight 260 g/m ² N Pearl Card, manufactured by Mitsubishi Paper Mills) was used instead of the paper having a cast-coated layer as in Example 1. The other processing methods and materials were the same as in Example 1.
The arithmetic mean roughness Ra of the surface of the paper substrate was 1.92 μm.
(Comparative Example)
Instead of the paper substrate with the cast-coated layer of Example 1, a so-called uncoated wood-free paper (basis weight 125 g/ ^m2 AKD, manufactured by Hokuetsu Kishu Paper Co., Ltd.) without a cast-coated or clay-coated layer was used. The other processing methods and materials were the same as those of Example 1.

The arithmetic mean roughness Ra of the paper substrate surface was 3.15 μm.

(Evaluation of Set-Off)
In order to confirm the effect of the present invention, the offset conditions were reproduced and an evaluation was carried out.
Two sheets of release paper made under the same conditions are prepared, and the surface of one paper base material is overlapped with the surface resin layer of the other, and then the overlapped state is passed between a pair of parallel metal rolls and pressed. The metal rolls rotate by themselves and in opposite directions to each other, so they can grip and press the sheet.

The metal rolls have mirror-finished outer cylindrical surfaces, and rotate around their shafts. The shaft of the first metal roll is rotatable but fixed in position, while the shaft of the second metal roll is rotatable and can move in a direction that allows the distance between the second metal roll and the shaft to be adjusted. The second metal roll is also capable of varying the pressure applied to the first metal roll.

The pressing conditions for the metal roll were set at a feed rate of 1 m/min, a surface temperature of 25°C, and two pressing forces of 100 kN/m and 200 kN/m, and samples were created under these conditions. Ten samples were created for each condition.

The sheet was clamped and pressed between metal rolls set under the above conditions, after which the two release papers were peeled off and the surface of the surface resin layer that had been in contact with the paper substrate was observed.

The samples produced were evaluated based on the following criteria:

1. Appearance observation:
Visual inspection and magnified observation of the surface using a microscope (Keyence VK-8710) 2. Gloss measurement: Using a gloss meter (HORIBA GLOSS CHECKER IG-320)
3. Arithmetic mean roughness measurement: Using a shape analysis laser microscope (Keyence VK-8710)
(Appearance Observation)
For the visual inspection of the appearance, a 100 mm square sample cut from the back-bleeding sample produced by the above procedure was placed on a desk in a test environment with an illuminance of 400 lux (equivalent to a bright office), and five subjects (quality control and technical personnel) visually inspected the sample from 500 mm above to judge its appearance.

We determined whether the mirror-like surface resin layer of the release paper was cloudy and whether the shape of the fibers in the paper base material was transferred to the surface resin layer.

Photographs were also taken at a magnification of approximately 100x using a Keyence shape analysis laser microscope (VK-8710).

(Measurement of Glossiness)
The offset of the samples of the examples and comparative examples was measured using a gloss meter (IG-320 <60° reflection>) manufactured by Horiba, Ltd. The measurements were carried out 10 times, and the average value was calculated.

(Arithmetic mean roughness measurement)
The offset of the examples and comparative examples of the samples was measured using a shape analysis laser microscope (VK-8710) manufactured by Keyence Corporation. The average value is obtained by measuring an area of 1 mm square 10 times.

The above evaluation results are summarized in Table 1.

離型紙の表面樹脂層を押圧していないサンプルＳ１（図１３）は、当初の表面性状を有している。このサンプルＳ１を基準とし、他のサンプルを押圧することによって、どのように表面性状が変化していくかを観察した。

Sample S1 (FIG. 13), in which the surface resin layer of the release paper was not pressed, had the original surface texture. Using sample S1 as a reference, the other samples were pressed to observe how their surface textures changed.

Of the samples after pressing, sample S3 (Fig. 15) and sample S7 (Fig. 19), which are release papers of Example 1 of the present invention, and sample S4 (Fig. 16) and sample S8 (Fig. 20), which are release papers of Example 2 of the present invention, are good products. Sample S5 (Fig. 17), which is the release paper of Example 3 of the present invention, is good, and sample S9 (Fig. 21) also shows some deterioration in quality but can be considered good.

In the case of conventional release paper, sample S2 (Fig. 14) shows transfer of the fibers from the paper base material, which indicates a decline in quality. Sample S6 (Fig. 18) shows significant transfer of the fibers from the paper base material, making it a defective product.

The thin lines running from top to bottom that are common to all the photographs are marks left by the mirror-finished roll surface and are barely visible to the naked eye. As a result, the surface of the resin layer on the release paper maintains its mirror-like appearance.

The evaluation was mainly done by visually inspecting the appearance, but it was found that if the decrease in glossiness measured by a measuring device for a sample pressed at 100 kN/m was within 10% of the initial value, this was almost consistent with an evaluation of a product as being good based on visual inspection, and it was found that the evaluation could be made by measuring the glossiness rather than by visual inspection by the examiner.

The overall surface roughness measurements at a pressure of 200 kN/m in Table 1 are greater than those at a pressure of 100 kN/m, but the judgment based on appearance observation does not change significantly.

This is thought to be because measuring the surface roughness of a sample pressed at 200 kN/m significantly picks up variations in density in the paper's surface direction, making it difficult to apply to evaluating the smoothness of the paper's surface. In other words, by strongly compressing the paper in the thickness direction, the areas of high density become convex, and the areas of low density become concave. As a result, the surface roughness is more affected by variations in density in the paper's surface direction than by the smoothness of the paper's surface.

The clay coat layer has the effect of increasing the smoothness of the paper surface. Furthermore, even if the paper is strongly compressed in the thickness direction and the surface roughness becomes rough according to the measured values, it has the effect of preventing the shape of the paper fibers from being transferred to the surface resin layer of the release paper. This is because the clay coat layer is highly effective at concealing the unevenness of the paper fibers.

In this way, the release paper of the present invention does not exhibit offset even when pressed in a stacked state, and the shape of the shaped portion can be maintained in good condition. In other words, even if a large external force or internal stress occurs during transportation or storage of the release paper, the quality is unlikely to be damaged. Therefore, not only is it useful for maintaining quality, but it also eliminates the need for excessive care in transportation and storage operations, contributing to improved work efficiency and cost reduction.

The release paper of the present invention can maintain the quality of the release paper, particularly preventing deterioration of quality that occurs during transportation and storage, and can contribute to improving the quality and reducing the costs of various shaped objects, including synthetic leather, produced using the release paper.

1 Release paper roll 2 Release paper (conventional product)
21 Paper base material (conventional product)
22 Surface resin layer (conventional product)
23 Surface of the surface resin layer (conventional product)
24. Forming section (conventional product)
25 Surface of paper substrate (conventional product)
26 Convex part caused by paper fibers (conventional product)
27 Contact part (conventional product)
28 Concave (conventional product)
3 Winding core 4 Release paper (present invention)
41 Paper base material (present invention)
42 Surface resin layer (present invention)
43 Surface of surface resin layer (present invention)
44 Shaped portion (present invention)
45 Smoothing layer 46 Shaped convex portion 47 Shaped concave portion 48 Contact portion (present invention)
49 Convex portion due to paper fibers (present invention)
5 Shaped body 51 Shaped resin layer (shaped body)
52 Base material layer (object to be shaped)
53 Part to be shaped (body to be shaped)
6 Synthetic leather 61 Shaped resin layer (synthetic leather)
62 Base material layer (synthetic leather)
63 Shaped part (synthetic leather)
64 Convex part (synthetic leather)
7 Laminated sheet 70 Extruder 71 Pressing roll (for mirror finishing)
72 Mirror finish roll 73 Resin 74 Original plate 75 Plate surface 76 Pressing roll (for shaping)
80 Surface S1 of smoothing layer of paper substrate Sample for offset evaluation (see Table 1)
S2 Sample for evaluating offset (see Table 1)
S3 Sample for evaluating offset (see Table 1)
S4 Sample for evaluating offset (see Table 1)
S5 Sample for evaluating offset (see Table 1)
S6 Sample for evaluating offset (see Table 1)
S7 Sample for evaluating offset (see Table 1)
S8: Sample for evaluating offset (see Table 1)
S9 Sample for evaluating offset (see Table 1)

Claims (3)

A paper substrate;
A surface resin layer provided on one surface of the paper base material and having an uneven surface;
a smoothing layer that is provided on the other surface of the paper base material and smoothes the surface of the paper base material;
The smoothing layer is a clay coat layer,
A roll-shaped release paper, wherein the coating amount of the clay coating layer is 5 g/m ² to 40 g/m ² in terms of basis weight after drying. The release paper according to claim 1 , characterized in that the arithmetic mean roughness Ra of the surface of the smoothing layer is 0.50 to 2.00 μm. The release paper according to claim 1 or 2 , wherein the smoothing layer has a thickness of 10 μm to 60 μm.

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