Decorative sheet and method for manufacturing a decorative sheet

Abstract

The present invention provides decorative sheets and the like that can be recognized over a wide viewing angle, even for designs that are monochromatic or dark in color and have little variation in shade. [Solution] The glossiness of the surface of a decorative sheet or the like is measured at n points of predetermined length and in a linear fashion at predetermined intervals, with m to m + n (where m and n are natural numbers of 1 or more) as multiple measurement points, and the glossiness of the obtained n points is measured at X1 to X n The difference in gloss between adjacent measurement points is Y2 (=X2-X1) ~ Y n (=X n -X n-1 In the measurement chart obtained when the following conditions are met, which shows the relationship between multiple measurement points and the difference in glossiness, the standard deviation of the variation in glossiness difference (%) is set to a value within the range of 0.29 to 1%, and furthermore, the ratio of the maximum value to the minimum value of the glossiness at n points is set to a value of 1.5 or higher.

Description

[Technical Field]

[0001] This invention relates to decorative sheets and methods for manufacturing decorative sheets. In particular, it relates to decorative sheets that allow for the realistic recognition of a design, even with single-color or dark-colored designs with little variation in shade, from a wide viewing angle, and to methods for manufacturing such decorative sheets. [Background technology]

[0002] Conventionally, for interior or exterior building materials such as walls, ceilings, floors, and entrance doors, as well as joinery or structural components such as window frames, doors, handrails, baseboards, moldings, and trim, and for roof surface materials, kitchen cabinets, furniture, or low-voltage electrical appliances, and cabinetry for office equipment, and for interior or exterior building materials for vehicles, it is common to use metal components such as steel plates, resin components, or wood components as the substrate, and then laminate decorative sheets onto these substrates.

[0003] In recent years, with the diversification of consumer preferences, decorative sheets and decorative components using low-luminosity colors such as black, dark gray, navy blue, dark purple, reddish-brown, and maroon have become popular. Conventionally, decorative sheets and decorative materials exhibiting such dark colors generally have a uniform design across the entire surface, or a design that combines dark and light colors, allowing for a clear pattern to be seen from any distance.

[0004] Therefore, decorative sheets have been proposed that attempt to reproduce a more realistic wood grain design by, for example, expressing a low-gloss finish (see, for example, Patent Document 1). More specifically, it is a decorative sheet having at least a surface protection layer on a base material, the surface protection layer containing a curable resin and an inorganic filler, the content of the inorganic filler being 12 to 25 parts by mass with respect to 100 parts by mass of the curable resin, the surface on the opposite side to the surface facing the base material of the surface protection layer having an uneven pattern, the area ratio of the recesses in the uneven pattern being 15% or more, and when the width of the frontage in the short side direction of the recess is b1 (μm), the width of the bottom in the short side direction of the recess is b2 (μm), and the depth of the recess is h (μm), it is a decorative sheet that simultaneously satisfies the following mathematical formulas (1) to (3). Mathematical formula (1): b2 / h ≥ 4.2 Mathematical formula (2): b2 / b1 > 0.22 Mathematical formula (3): 130 μm ≥ h ≥ 5 μm

[0005] In addition, a decorative sheet that expresses a delicate dark-colored pattern design has been proposed, which is visually recognized as a single dark color from a distance, but a pattern corresponding to the shade of the dark color is visually recognized from close up (for example, see Patent Document 2). More specifically, it has a base sheet and a decorative layer including a pattern layer that covers at least a part of a plane, in which a plurality of regions are adjacent to each other in a plan view, and the CIE (International Commission on Illumination) L * a * b * value in the color system and the L * value of the region adjacent to the one region are different from each other, and the L * values of the one region and the region adjacent to the one region are 0 or more and 40 or less, and it is a dark-colored pattern decorative sheet. *

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, since the cosmetic sheet disclosed in Patent Document 1 focuses on reproducing a more realistic wood grain design, although it has a low glossiness, it is a design including light colors, so it cannot be said to be a cosmetic sheet presenting dark colors, which has been in increasing demand in recent years. In addition, as for cosmetic sheets and cosmetic members presenting dark colors, they are limited to those having a uniform design on the entire surface or a distinct design property by a combination of dark colors and light colors, with few variations and not being able to fully meet the diversification of consumers' preferences.

[0008] On the other hand, the cosmetic sheet etc. of Patent Document 2 is expressed by printing the pattern of the design, and as an expression subordinate to the pattern of the design in order to recognize a more realistic design, it was trying to express by combining and synchronizing concavo-convex shapes with the pattern. Therefore, for a design represented by a single color with few shades, there was a problem that it could not be recognized at a wide viewing angle by only printing it, and it was inferior in the visibility of a realistic design. In addition, in the case of the cosmetic sheet etc. of Patent Document 2, the substrate sheet and the CIEL * a * b * L value of the L*a*b color system in one region where a plurality of regions are adjacent to each other in plan view, and in the region adjacent to the one region, the L * value had to be controlled to be different from each other. * Furthermore, in the case of the cosmetic sheet etc. of Patent Document 2, it is provided with a decorative layer including a pattern layer including a pattern covering at least a part of the plane, and the L * value of the one region and the region adjacent to the one region had to be set to 0 or more and 40 or less to make a dark-colored patterned cosmetic sheet.

[0009] Therefore, in view of the above circumstances, the present inventors made diligent efforts and discovered that by controlling the variation in gloss difference between adjacent measurement points and the ratio of the maximum / minimum gloss values ​​measured under predetermined conditions, a decorative sheet that can effectively recognize a realistic design can be obtained, thus completing the present invention. In other words, the object of the present invention is to provide a decorative sheet that allows for the recognition of a realistic design over a wide viewing angle, and an efficient method for manufacturing such a decorative sheet, even when the pattern and the relief shape are not synchronized, in a dark-colored decorative sheet with little variation in shade, such as a single color, by controlling the standard deviation of the variation in gloss difference between adjacent measurement points measured under predetermined conditions. [Means for solving the problem]

[0010] According to the present invention, a decorative sheet having a predetermined surface unevenness is used, and the glossiness of the surface of the decorative sheet is measured at a predetermined length and at equal intervals in a straight line at multiple measurement points m to m+n (where m and n are natural numbers of 1 or more, and the same applies hereinafter), at n points (for example, 80 points), and the glossiness (%) of the obtained n points is measured at X1 to X n The difference in glossiness (%) between adjacent measurement points is calculated as Y2(=X2-X1)~Y n (=X n -X n-1 In the measurement chart obtained when this is the case, which shows the relationship between multiple measurement points and the gloss difference, it is preferable to set the value of the standard deviation of the variation in gloss difference (%) to a value greater than or equal to a predetermined value. More specifically, a decorative sheet having a predetermined surface unevenness, wherein the glossiness of the surface of the decorative sheet is measured at multiple measurement points m to m+n (where m and n are natural numbers of 1 or more) at predetermined lengths and at equal intervals in a straight line at n locations, in accordance with JIS Z 8741:1997, and the glossiness (%) of the obtained n locations is expressed as X1 to X n The difference in glossiness (%) between adjacent measurement points is calculated as Y2 (=X2-X1) ~ Y n (=X n -X n-1The decorative sheet is characterized in that, in a measurement chart showing the relationship between multiple measurement points and the difference in glossiness obtained when the glossiness difference (%) is set to a value within the range of 0.29 to 1%, and furthermore, the ratio of the maximum value to the minimum value of the glossiness at n points is set to a value of 1.5 or more. In other words, by controlling the standard deviation of the variation in glossiness and the ratio of the maximum / minimum glossiness to a predetermined value or higher, it is possible to create a decorative sheet that exhibits a realistic design even in designs with little variation in shade, and even in cases of free patterns where the pattern and relief are not synchronized, allowing for recognition of the design's realism across a wide viewing angle. Furthermore, the standard deviation value for the variation in gloss level can be used as a control factor when judging the quality of the manufacturing, resulting in a decorative sheet with even greater quantitative accuracy and reproducibility in terms of good design and other characteristics. Furthermore, the standard deviation value for the variation in gloss level can be adjusted by appropriately changing the embossing conditions (pressure, embossing temperature, rotation speed, etc.), the type of embossing roll (surface hardness, embossing height, embossing shape), and the composition of the decorative sheet (material, thickness, hardness, etc.).

[0011] Furthermore, when constructing the decorative sheet of the present invention, it is preferable that the difference between the maximum and minimum values ​​of the gloss difference be within the range of 40 to 80%. In other words, by controlling the difference between the maximum and minimum values ​​of the gloss difference in this way, it is possible to create a decorative sheet that allows for the recognition of a realistic design across a wider viewing angle. Furthermore, by adopting the difference between the maximum and minimum values ​​based on gloss level as one of the control factors, it becomes possible to use this as a management factor when judging the quality of manufacturing for design aspects, which are prone to individual differences. As a result, it becomes possible to create decorative sheets with even greater reproducibility and quantitative accuracy regarding good design aspects.

[0012] Furthermore, the decorative sheet of the present invention is preferably a single color, exhibiting a dark color such as black, dark gray, navy blue, dark purple, reddish-brown, or maroon.

[0013] Furthermore, it is preferable that the decorative sheet of the present invention has a wood grain pattern, a Japanese paper pattern, or a glossy pattern which is one of the geometric patterns.

[0014] When constructing the decorative sheet of the present invention, it is preferable that the arithmetic mean roughness Ra, measured in accordance with JIS B 0601:1982 with respect to a predetermined surface unevenness, be within the range of 5 to 20 μm. In this way, by setting the arithmetic mean roughness Ra to a value within a predetermined range with respect to the predetermined surface irregularities, such Ra can also be used as a control factor when judging the quality of the manufacturing. As a result, it is possible to produce a decorative sheet with predetermined surface irregularities that are more reproducible and quantitative in terms of good design and other aspects.

[0015] When constructing the decorative sheet of the present invention, it is preferable that the overall thickness be within the range of 50 to 500 μm. By setting the overall thickness of the decorative sheet within a predetermined range, the mechanical properties, handling, and decorative qualities of the decorative sheet can be improved, and furthermore, embossing and other surface treatments, which are the surface conditions of the present invention, can be easily and reproducibly implemented.

[0016] In constructing the decorative sheet of the present invention, it is preferable that the type of decorative sheet having a predetermined surface unevenness is polyvinyl chloride resin, polyester resin, or polyolefin resin. By specifying the type of decorative sheet in this way, the mechanical properties, handling, decorative properties, transparency, etc. of the decorative sheet can be improved, and furthermore, embossing and other surface treatments that result in the surface state of the present invention can be easily and reproducibly carried out.

[0017] Another aspect of the present invention is a method for manufacturing a decorative sheet having a predetermined surface unevenness, characterized by comprising the following steps (1) to (2). (1) Step of preparing a resin composition for forming a decorative sheet. (2) A step of forming a decorative sheet derived from a resin composition, wherein the gloss is measured by an embossing roll at multiple measurement points m to m + n (where m and n are natural numbers of 1 or more) at predetermined lengths and at equal intervals in a straight line at n points, in accordance with JIS Z 8741:1997, and the gloss of the obtained n points is measured from X1 to X n The difference in gloss between adjacent measurement points is Y2 (=X2-X1) ~ Y n (=X n -X n-1 In the measurement chart obtained when the relationship between multiple measurement points and the gloss difference is set, the standard deviation of the variation in gloss difference (%) is set to a value within the range of 0.29 to 1%, and furthermore, the ratio of the maximum value to the minimum value of the gloss at n points is set to a value of 1.5 or more in the process of forming a decorative sheet. In other words, even in cases where the design has little variation in shade, such as a single color, by controlling the standard deviation of the variation in gloss difference between adjacent measurement points measured under predetermined conditions, it is possible to efficiently manufacture decorative sheets that allow for the recognition of a realistic design across a wide viewing angle. Furthermore, by adopting numerical values ​​based on differences in glossiness, it becomes possible to use this as a control factor when judging the quality of manufacturing, especially for design aspects that are prone to individual variations. Therefore, it is possible to efficiently manufacture decorative sheets that have good quantitative accuracy and reproducibility in judging the design and other aspects of decorative sheets. [Brief explanation of the drawing]

[0018] [Figure 1] Figures 1(a) to 1(c) are diagrams provided to illustrate the respective forms of the decorative sheets. [Figure 2] Figure 2(a) is provided to illustrate the relationship between the surface irregularities (convex shape) of the decorative sheet and the difference in glossiness at adjacent measurement points, and Figure 2(b) is provided to illustrate the relationship between a predetermined surface irregularity (convex shape with flat parts) of the decorative sheet and the difference in glossiness at adjacent measurement points (part 1). [Figure 3] Figure 3 is provided to explain the relationship between the predetermined surface irregularities (generally triangular shape) of the decorative sheet and the difference in glossiness at adjacent measurement points (part 2). [Figure 4] Figure 4(a) is a diagram illustrating the relationship between the glossiness of a decorative sheet and its arithmetic mean roughness (Ra), and Figure 4(b) is a diagram illustrating the relationship between the difference in glossiness between adjacent measurement points on a decorative sheet and its arithmetic mean (Ra). [Figure 5] Figure 5(a) shows the specular gloss at each measurement point of the decorative sheet #1 corresponding to Example 1, and Figure 5(b) shows the difference in gloss at adjacent measurement points. [Figure 6] Figure 6(a) shows the specular gloss at each measurement point of the decorative sheet #2 corresponding to Example 2, and Figure 6(b) shows the difference in gloss at adjacent measurement points. [Figure 7] Figure 7(a) shows the specular gloss at each measurement point of the #3 decorative sheet corresponding to Example 3, and Figure 7(b) shows the difference in gloss between adjacent measurement points. [Figure 8] Figure 8(a) shows the specular gloss at each measurement point of the #4 decorative sheet corresponding to Comparative Example 1, and Figure 8(b) shows the difference in gloss at adjacent measurement points. [Figure 9] Figure 9(a) shows the gloss distribution of a #5 decorative sheet equivalent to Comparative Example 2, and Figure 9(b) shows the difference in glossiness based on the same gloss distribution figure. [Figure 10] Figure 10(a) shows the gloss distribution of a #6 decorative sheet equivalent to Comparative Example 3, and Figure 10(b) shows the difference in glossiness based on the same gloss distribution figure. [Figure 11] Figure 11 is a diagram illustrating a method for evaluating the visibility of decorative sheets. [Figure 12] Figure 12 illustrates the relationship between the standard deviation of the variation in glossiness difference between adjacent measurement points and the evaluation of the visibility of the decorative sheet. [Modes for carrying out the invention]

[0019] [First Embodiment] The first embodiment is a decorative sheet having a predetermined surface unevenness, as shown in Figure 1(a), etc., wherein the glossiness of the surface of the decorative sheet is measured at multiple measurement points m+n (where m and n are natural numbers of 1 or more) at a predetermined length and at equal intervals in a straight line at n points, in accordance with JIS Z 8741:1997, and the glossiness of the obtained n points is measured from X1 to X n The difference in gloss between adjacent measurement points is Y2 (=X2-X1) ~ Y n (=X n -X n-1 The decorative sheet is characterized in that, in a measurement chart showing the relationship between multiple measurement points and the difference in glossiness obtained when the glossiness difference (%) is set to a value within the range of 0.29 to 1%, and furthermore, the ratio of the maximum value to the minimum value of the glossiness at n points is set to a value of 1.5 or more. The decorative sheet of the first embodiment will be described in detail below, broken down by its constituent elements.

[0020] 1. Decorative sheet having a predetermined surface texture. (1) Appearance The decorative sheet having a predetermined surface unevenness (which may be referred to as a decorative sheet substrate when combined with other layers) is not limited to the following embodiments, but representative embodiments include embodiments 1) to 8) below. 1) A decorative sheet consisting of a single component of a decorative sheet substrate. 2) A decorative sheet consisting of a decorative sheet base material and an adhesive layer. 3) The decorative sheet consists of a two-layer structure: a primer layer and a decorative sheet substrate. 4) The decorative sheet consists of a three-layer structure: a primer layer, a decorative sheet substrate, and an adhesive layer. 5) This decorative sheet consists of a three-layer structure: a clear layer, a printed layer, and a decorative sheet substrate. 6) This decorative sheet consists of four layers: a clear layer, a printed layer, a decorative sheet substrate, and an adhesive layer. 7) This decorative sheet consists of four layers: a primer layer, a clear layer, a printed layer, and a decorative sheet substrate. 8) This decorative sheet consists of five layers: a primer layer, a clear layer, a printed layer, a decorative sheet substrate, and an adhesive layer.

[0021] The adhesive layer mentioned above is typically a resin layer used to attach decorative sheets (decorative sheet substrates) to wall substrates, etc. Furthermore, the primer layer is typically an easy-to-adhere adhesive layer used to laminate other resin layers onto the surface of a decorative sheet (decorative sheet substrate). Furthermore, the clear layer is typically a transparent resin layer applied to the surface of a decorative sheet (decorative sheet substrate) to provide protection without altering visibility. Furthermore, the printed layer is a decorative layer formed by printing letters, figures, symbols, etc., onto the surface of a decorative sheet (decorative sheet substrate).

[0022] Furthermore, decorative sheets are generally preferably provided with a release liner on either one or both sides. In other words, the release liner can be effectively protected from surrounding dust and dirt during storage and transportation until the decorative sheet is actually used. Furthermore, if the decorative sheet has a release liner on both sides or one side, handling, positioning, and application processes can be improved.

[0023] (2) Predetermined surface irregularities Furthermore, while there are no particular limitations on the form of the predetermined surface irregularities, it is preferable that the decorative sheet has at least one pattern, such as a wood grain pattern, a Japanese paper pattern, and a geometric pattern. The reason for this is that by incorporating such specific patterns, the decorative properties of the resulting decorative sheet can be enhanced, controlled, and surface treatment can be facilitated.

[0024] Therefore, with respect to the predetermined surface irregularities of the decorative sheet, it is preferable to set the arithmetic mean roughness Ra to a value within the range of 5 to 20 μm. The reason for this is that by controlling the arithmetic mean roughness Ra to a specific value, the desired pattern can be clearly recognized, and furthermore, it can be stably formed by processes such as embossing. Furthermore, Ra can be used as a control factor when judging the quality of manufacturing, and as a result, it is possible to produce decorative sheets with a predetermined surface unevenness that is even more reproducible and quantitative in terms of good design and other aspects. Therefore, it is more preferable to set the arithmetic mean roughness Ra of the predetermined surface irregularities of the decorative sheet to a value in the range of 6 to 18 μm, and even more preferable to set it to a value in the range of 7 to 16 μm.

[0025] (3) Specular gloss and gloss difference (3)-1 Interval When selecting measurement points with an arbitrary point as the end, it is generally preferable to select four or more points at equal intervals within the range of 1 to 12 mm, preferably within the range of 3 to 11 mm, and even more preferably within the range of 5 to 10 mm, as shown in Figures 2(a) to (b) and Figure 3.

[0026] Here, Figure 2(a) is provided to illustrate the relationship between the surface irregularities (convex shape) of the decorative sheet and the difference in glossiness at adjacent measurement points, and Figure 2(b) is provided to illustrate the relationship between a predetermined surface irregularity (convex shape with flat parts) of the decorative sheet and the difference in glossiness at adjacent measurement points. Furthermore, Figure 3 is provided to explain the relationship between the predetermined surface irregularities (generally triangular shape) of the decorative sheet and the difference in glossiness at adjacent measurement points. In other words, by measuring at least four arbitrary points in a straight line, it is possible to observe the continuous change in glossiness in the design pattern. Therefore, for example, by checking whether the first relationship and the second relationship, or either one of the relationships, are satisfied, four or more adjacent locations can be identified.

[0027] (3)-2 Measurement length When measuring and controlling the difference in glossiness between adjacent measurement points, it is generally preferable to set the measurement length within the range of 40 mm to 1000 mm. The reason for this is that by using multiple points as ends and measuring at least four measurement points in a straight line, it is possible to determine the minimum length, maximum length, and consequently the size of the design, thereby determining the size of the design pattern and other elements that are visible. Furthermore, using such measurement lengths makes it easier to miniaturize the equipment used to create decorative sheets. Therefore, it is more preferable to set the measurement length to a value within the range of 100 mm to 800 mm, and even more preferable to set it to a value within the range of 200 mm to 640 mm.

[0028] (3)-3 Straight Furthermore, when measuring and controlling the difference in gloss between adjacent measurement points, it is preferable to measure at least four or more points, and usually measure the gloss in a linear fashion. The reason for this is that zigzag or rectangular (right-angled) shapes make it impossible to accurately determine the continuous changes in glossiness in the design pattern. However, even though we say "measure in a straight line," it doesn't necessarily have to be a physically straight line. It's sufficient to measure the glossiness by passing through at least four measurement points in a de facto straight line.

[0029] (3)-4 Standard deviation of the variation in gloss level Furthermore, when measuring and controlling the difference in glossiness between adjacent measurement points, the standard deviation of the variation in glossiness difference is set to a value of 0.25% or more, and within the range of 0.29% to 1%. In other words, in a measurement chart showing the relationship between multiple measurement points and the difference in glossiness, the standard deviation of the variation in glossiness difference (%) is set to a value greater than or equal to a predetermined value. The reason for this is that when the standard deviation of the variation in gloss difference (%) falls below 0.25%, it becomes difficult to recognize the realistic design of a decorative sheet with a single color or dark color and little variation in shade, even at a wide viewing angle.

[0030] Here, referring to Figure 12, we will explain the relationship between the standard deviation (%) of the variation in glossiness difference between adjacent measurement points and the visibility evaluation (relative value) of the decorative sheet. In Figure 12, the horizontal axis shows the standard deviation (%) of the variation in glossiness difference between adjacent measurement points, and the vertical axis shows the relative value of the visibility evaluation. In other words, the visibility evaluation shown in Example 1, described later, is assigned a score of 5 points for ◎, 3 points for ○, 1 point for △, and 0 points for ×, and the visibility evaluation is based on its relationship to the standard deviation of the variation in gloss difference between adjacent measurement points. As can be easily seen from the characteristic curve shown in Figure 12, when the standard deviation of the variation in gloss difference between adjacent measurement points is less than 0.25%, the visibility evaluation (relative value) is almost 0. In contrast, when the standard deviation of the variation in glossiness difference between adjacent measurement points becomes 0.25% or higher, and furthermore, as in Example 2, when it becomes 0.29% or higher, there is a tendency for the visibility evaluation (relative value) to improve sharply. Therefore, when evaluating visibility (relative value), if a good result is desired, it is preferable to set the standard deviation of the variation in glossiness difference between adjacent measurement points to a value of 0.29% or higher. If an even better visibility evaluation is desired, a value of 0.3% or higher is preferable. Furthermore, if a consistently good visibility evaluation is desired, a value within the range of 0.4% to 1.0% is considered appropriate.

[0031] (3)-5 Maximum - Minimum Gloss Difference When measuring the glossiness of n locations and the difference in glossiness between adjacent locations at multiple measurement points m to m+n, the glossiness of n locations is measured sequentially from one end to the other, X1 to X n The difference in gloss between adjacent measurement points is calculated as Y2(=X2-X1)~Y n (=X n -X n-1 ) Based on this premise, it is preferable that the (maximum value - minimum value) of the gloss difference be within the range of 40 to 80%. The reason for this is that by keeping the (maximum value - minimum value) of the glossiness of adjacent measurement points within a predetermined range, it is possible to control the maximum value, minimum value, and variation of the glossiness difference.

[0032] (3)-6 Maximum / Minimum Glossiness Furthermore, it is preferable that the maximum / minimum value of the specular gloss (hereinafter sometimes simply referred to as gloss) of adjacent measurement points, based on the gloss of n points, be 1.5 or greater. The reason for this is that by setting the maximum / minimum gloss values ​​of adjacent measurement points to be above a predetermined value, a visible difference in gloss values ​​can be ensured. However, if the maximum / minimum gloss values ​​of adjacent measurement points become excessively large, it may become difficult to control surface roughness, such as surface irregularities. Therefore, it is more preferable to set the maximum / minimum gloss value of adjacent measurement points to a value within the range of 1.8 to 10, more preferably within the range of 1.8 to 8, and even more preferably within the range of 2 to 6. Furthermore, the maximum / minimum value of the gloss difference is preferably -0.8 or less, more preferably -0.9 or less, and even more preferably -1 or less.

[0033] (3)-7 Surface roughness (arithmetic mean roughness Ra) With respect to the specified surface irregularities, it is preferable that the arithmetic mean roughness Ra, measured in accordance with JIS B 0601:1982, be within the range of 5 to 20 μm. The reason for this is that by setting the arithmetic mean roughness Ra to a value within a predetermined range, such Ra can also be used as a control factor when judging the quality of the manufacturing. As a result, a decorative sheet can be produced that has a predetermined surface texture with even greater reproducibility and quantitative accuracy in terms of good design and other properties. Therefore, with respect to a given surface irregularity, it is more preferable to set the arithmetic mean roughness Ra to a value in the range of 10 to 20 μm, and even more preferable to set it to a value in the range of 12 to 18 μm.

[0034] (4) Continuity of arithmetic mean roughness (4)-1 If positive Furthermore, Y is the difference in gloss between adjacent measurement points at multiple measurement points m to m+n. m ~Y m+n However, all values ​​are positive, and the arithmetic mean roughness Ra at multiple measurement points is Ra m >Ra m+1 >Ra m+2 >Ra m+3 It is preferable that the following relationship (the first relationship) is satisfied. In other words, at least four points among multiple measurement points m to m+n have measurement points m to m+3 (where m is a natural number greater than or equal to 1) where the difference in glossiness between these adjacent measurement points is positive at three or more consecutive points, and the arithmetic mean roughness Ra at these measurement points m to m+3 is Ra m >Ra m+1 >Ra m+2 >Ra m+3 This means that it is preferable to satisfy the relationship (the first relationship). The reason for this is that, as the glossiness at the measurement point increases sequentially, the maximum height Rz does not increase proportionally, but rather the arithmetic mean roughness Ra decreases proportionally. Therefore, it is thought that the proportionally decreasing arithmetic mean roughness Ra influences the ability to recognize a realistic design across a wide viewing angle, even with monochromatic or color designs that have little variation in shade.

[0035] (4)-2 In the case of a negative value Furthermore, Y is the difference in glossiness between multiple different measurement points m'~m'+n. m´ ~Y m´+n If all of them are negative, and the arithmetic mean roughness Ra at each of the multiple measurement points is Ra m´ <Ra m´+1 <Ra m´+2 <Ra m´+3 It is preferable that the following relationship (the second relationship) is satisfied. In other words, in multiple measurement locations m'~m'+n that are different from m~m+n, at least four adjacent measurement locations, there is a measurement location m'~m'+3 (where m' is a natural number greater than or equal to 1) where the difference in glossiness between these adjacent measurement locations is negative at three or more consecutive locations, and the arithmetic mean roughness Ra at the measurement location m'~m'+3 is Ra m´ <Ra m´+1 <Ra m´+2 <Ra m´+3 This means that it is preferable to satisfy the relationship (the second relationship). This is because, as the glossiness at the measurement point decreases sequentially, the maximum height Rz does not decrease proportionally, but rather the arithmetic mean roughness Ra increases proportionally and continuously. Therefore, it is thought that the proportionally and continuously decreasing arithmetic mean roughness Ra influences the ability to recognize realistic designs across a wide viewing angle, even with color designs that have little variation in shade.

[0036] Furthermore, for partial gloss differences at multiple measurement points, the first relationship will be satisfied by continuously positive cases, the second relationship will be satisfied by negative cases, and such positive and negative cases will repeatedly occur. Therefore, even if the decorative sheet is a single color with little variation in shade, if either of the first or second relationship is satisfied, the realistic design can be recognized at a wide viewing angle. However, in order to obtain good visibility, it is more preferable to satisfy both the first and second relationships.

[0037] Here, referring to the scatter plots of the data in Figures 4(a) and 4(b), we will explain the relationship between glossiness and arithmetic mean roughness (Ra) at the measurement points of the decorative sheet, and the relationship between the difference in glossiness at adjacent measurement points of the decorative sheet and arithmetic mean roughness (Ra). Furthermore, the gloss value of the decorative sheet in Figure 4(a) and the gloss difference value of the decorative sheet in Figure 4(b) are based on Example 1 and Comparative Example 1, which will be described later. The data scatter plot in Figure 4(a) suggests a significant correlation between the glossiness of the decorative sheet and its arithmetic mean roughness (Ra).

[0038] On the other hand, the data scatter plot in Figure 4(b) is a diagram that explains the relationship between the difference in glossiness between adjacent measurement points on the decorative sheet and the arithmetic plane (Ra). The data scatter plot in Figure 4(ba) suggests that there is no correlation between the difference in glossiness of the decorative sheets and the arithmetic mean roughness (Ra). Therefore, at four of the multiple measurement points m to m+n, the difference in glossiness between these adjacent measurement points is Y. m ~Y m+3 However, if three or more locations are positive consecutively (first relationship), or if four of the other multiple measurement points m'~m'+3 have a gloss difference Y m´ ~Y m´+3 When the value is negative in three or more consecutive places (second relationship), the visibility of the design becomes remarkably good.

[0039] (5) Types Furthermore, while there are no particular limitations on the type of decorative sheet having a predetermined surface unevenness when constructing the decorative sheet of the present invention, it is generally preferable that it be at least one of polyvinyl chloride resin, polyester resin, or polyolefin resin. The reason for this is that, with such resins, the decorative properties, mechanical properties, stability, adhesiveness, etc., of the final decorative sheet can be controlled relatively easily to a desired range of properties. Furthermore, these types of resins have the advantage of being relatively easy to obtain and inexpensive, even if they differ in thickness, weight-average molecular weight, and hardness.

[0040] (6) Thickness The thickness of the decorative sheet can be adjusted as appropriate depending on the application, but it is generally preferable to use a value within the range of 50 to 500 μm. The reason for this is that by controlling the thickness of the decorative sheet within this range, it becomes easier to exhibit the various properties of the decorative sheet, and also simplifies manufacturing. Therefore, it is more preferable to set the thickness of the decorative sheet to a value within the range of 80 to 350 μm, more preferably within the range of 100 to 300 μm, and most preferably within the range of 120 to 250 μm.

[0041] (7) Planar shape The shape of the decorative sheet is not particularly restricted and can be changed as appropriate depending on the application. Therefore, for example, it can be tape-shaped, triangular, square (rectangular), polygonal, circular, elliptical, or irregularly shaped.

[0042] (8) Form The decorative sheet may be in the form of a roll or as a single sheet. In that case, if the decorative sheet is in roll form, it is preferable that it has dimensions of at least 90 cm in width and 1 m in length. Furthermore, if the decorative sheet is a single sheet, it is preferable that it has dimensions such as a side width of 50 cm and a length of 1 m or more.

[0043] [Second Embodiment] A second embodiment of the present invention is a method for manufacturing a decorative sheet having a predetermined surface unevenness, characterized in that it includes the following steps (1) to (2). (1) Step of preparing a resin composition for forming a decorative sheet. (2) A step of forming a decorative sheet derived from a resin composition, wherein the gloss is measured by an embossing roll at multiple measurement points m to m + n (where m and n are natural numbers of 1 or more) at predetermined lengths and at equal intervals in a straight line at n points, in accordance with JIS Z 8741:1997, and the gloss (%) of the obtained n points is measured from X1 to X n The difference in glossiness (%) between adjacent measurement points is calculated as Y2 (=X2-X1) ~ Y n (=X n -Xn-1 In the measurement chart obtained when the relationship between multiple measurement points and the gloss difference is set, the standard deviation of the variation in gloss difference (%) is set to a value within the range of 0.29 to 1%, and furthermore, the ratio of the maximum value to the minimum value of the gloss at n points is set to a value of 1.5 or more in the process of forming a decorative sheet. The manufacturing method of the decorative sheet according to the second embodiment will be described in detail below, divided by constituent elements, to the extent that it does not overlap with the first embodiment.

[0044] 1. Preparation of the resin composition This is the process of preparing a single-color resin composition. As the resin composition, a thermoplastic resin is used, and as described in the first embodiment, at least one resin material such as polyvinyl chloride resin, polyester resin, or polyolefin resin, as well as a coloring agent for coloring, can be suitably used, so a detailed explanation is omitted here.

[0045] Furthermore, when using polyvinyl chloride resin or the like, it is preferable to set its average degree of polymerization to a value within the range of 100 to 10000. This is because if the average degree of polymerization of polyvinyl chloride resin, etc., falls below 100, it may become difficult to maintain the desired shape, or the surface tack may become excessively high. On the other hand, if the average degree of polymerization of polyvinyl chloride resin or the like exceeds 10,000, it may become difficult to uniformly mix and disperse the components or to create a flame-retardant sheet of a predetermined uniform thickness. Therefore, it is more preferable to set the average degree of polymerization of the polyvinyl chloride resin to a value in the range of 500 to 5000, and even more preferable to set it to a value in the range of 800 to 2000. The average degree of polymerization of polyvinyl chloride resin can be calculated by comparing it with the molecular weight of the monomer using a GPC or GC-MS instrument.

[0046] 2. Process for forming decorative sheets (1) Basic process The process for forming a decorative sheet involves creating a predetermined polyvinyl chloride sheet (for example, in roll form, with a width of 90 cm or more, a length of 10 m or more, and a thickness of 70 μm or more) from a single-color resin composition. During this process, the surface can be embossed to create a glossy pattern with predetermined irregularities, such as a wood grain pattern, to form the decorative sheet.

[0047] For example, to create a wood grain pattern as a glossy pattern, a polyvinyl chloride resin composition is prepared by mixing (A) 100 parts by weight of polyvinyl chloride resin with 20 parts by weight of plasticizer (DOP) and 0.5 parts by weight of black pigment during the molding of the polyvinyl chloride sheet. Next, a desired uneven surface can be formed using a predetermined embossing roll so that a wood grain pattern is visible as a glossy pattern.

[0048] (2) Additional manufacturing process Furthermore, when creating a typical basic form 1) to 8) of a decorative sheet as described in the first embodiment, for example, when creating basic form 2) as a decorative sheet, it is preferable to include an additional step of forming an adhesive layer made of a predetermined adhesive resin, such as an acrylic adhesive resin, on the back surface of the decorative sheet substrate.

[0049] Similarly, to create basic form 3), it is preferable to include an additional step of forming a thin primer layer made of a predetermined resin on the surface of the decorative sheet substrate. Furthermore, in order to create basic form 4), it is preferable to include an additional step of forming an adhesive layer made of a predetermined resin on the back surface of the decorative sheet substrate of basic form 3).

[0050] Furthermore, in order to create the basic form 5), it is preferable to include an additional step of printing on the surface of a single-color decorative sheet substrate to form a printed layer, then applying a clear layer to the surface of the printed layer, and simultaneously forming an uneven shape using an embossing roll. Furthermore, when creating the basic form 6), it is preferable to include an additional step of forming an adhesive layer made of a predetermined resin on the back surface of the decorative sheet substrate of the basic form 5).

[0051] Furthermore, in order to create the decorative sheet of basic form 7), it is preferable to include an additional step of forming a primer layer on the surface of the decorative sheet substrate of basic form 5). Furthermore, in order to create the basic form 8), it is preferable to include an additional step of forming an adhesive layer made of a predetermined resin on the back surface of the decorative sheet substrate of the basic form 7).

[0052] (3) Inspection process It is preferable to include inspection steps to determine whether the resulting decorative sheet has a predetermined level of mirror gloss, surface roughness, etc., and whether its visibility is good or not. More specifically, it is preferable to measure the specular gloss and surface roughness of the obtained decorative sheet using a specular gloss meter (e.g., manufactured by Nippon Denshoku Industries Co., Ltd.) and a surface roughness meter (e.g., manufactured by Kosaka Laboratory Co., Ltd.), respectively, and to confirm that the values ​​are within a predetermined range. This inspection process may involve a 100% inspection of the decorative sheets, or it may be a random inspection conducted at a predetermined rate, taking into consideration production efficiency.

[0053] (3)-1 Mirror gloss In accordance with JIS Z 8741:1997, the specular gloss (%) was measured by irradiating the surface of the decorative sheet with laser light from a 60° angle at approximately 80 points along a straight line with a measurement interval of 8 mm and a measurement length of 640 mm. Furthermore, the difference in glossiness (%) between adjacent measurement points can be calculated from the glossiness values ​​of multiple measurement points and used as a basis for evaluation.

[0054] (3)-2 Surface roughness In accordance with JIS B 0601:1982, the arithmetic surface roughness (Ra) of the decorative sheet surface is measured at approximately 80 locations in a straight line, for example, with a measurement interval of 8 mm and a measurement length of 640 mm. Furthermore, it is preferable to express the surface irregularities of the decorative sheet using an arithmetic mean roughness based on multiple measurement points m~m+n (or m'~m'+n).

[0055] (3)-3 Visibility The visibility of the decorative sheet is evaluated according to the evaluation criteria shown in Example 1 described later, and it is more preferable to obtain an evaluation result of at least △, and more preferably 〇 or ◎. In other words, the visibility of the obtained decorative sheet was evaluated according to the criteria shown in Example 1, described later, by changing the angle (θ1) between the incident light from the light source 32 and the direction in which the viewer 34 sees the decorative sheet 30, as shown in Figure 11. Furthermore, θ1 × 2 is called the field of view, and there is a relationship where θ1 + θ2 equals 90°.

[0056] Furthermore, even when the decorative sheet is tilted at a 45° angle from the front (viewing angle of 90°), if the viewer can clearly recognize the design from the front of the decorative sheet (evaluation △), there is no practical problem. Furthermore, even when the decorative sheet is tilted 60° from the front (viewing angle of 120°), it is preferable if the design can be clearly recognized from the front of the decorative sheet (rated ○). Furthermore, even when the decorative sheet is tilted at a 75° angle from the front (viewing angle of 150°), it would be even more desirable if the design could be clearly recognized from the front of the decorative sheet (evaluation ◎). [Examples]

[0057] The present invention will be described in detail below based on examples. However, the scope of the present invention will not be narrowed by the description of the examples without any particular reason.

[0058] [Example 1] 1. Manufacturing process of decorative sheets (1) Preparation of polyvinyl chloride resin composition In a mixing container, 100 parts by weight of polyvinyl chloride resin with a weight-average molecular weight of 1,000,000 were placed in a ratio of 40 parts by weight of plasticizer (DOP) and 0.5 parts by weight of black pigment. These were then mixed and stirred until homogeneous to prepare a polyvinyl chloride resin composition.

[0059] (2) Process for forming decorative sheets Next, a single-color (black) polyvinyl chloride sheet (thickness: 150 μm) was obtained using the polyvinyl chloride resin composition removed from the mixing container in a calendering machine. Next, a decorative sheet with a predetermined uneven pattern was created on the surface (one side) of the obtained polyvinyl chloride sheet using an embossed roll with a wood grain pattern created by laser engraving. In other words, a wood grain pattern was applied to the surface as a glossy pattern using a predetermined embossing roll, resulting in a decorative sheet with a wood grain pattern (decorative sheet #1).

[0060] 2. Evaluation process for decorative sheets (1) Mirror gloss In accordance with JIS Z 8741:1997, the 60° specular gloss (hereinafter sometimes simply referred to as gloss) of the surface of the decorative sheet was measured at approximately 80 points along a straight line with a measurement interval of 8 mm and a measurement length of 640 mm, using a specular gloss meter COLUMUN 07 (manufactured by Nippon Denshoku Industries, Ltd.). Specifically, as shown in Table 1, the average, maximum, minimum, maximum-minimum, maximum / minimum, and standard deviation of specular gloss of the decorative sheet were calculated. Furthermore, as shown in Table 1, the mean, maximum, minimum, maximum-minimum, maximum / minimum, and standard deviation of the gloss difference were similarly calculated from the obtained specular gloss values. Figure 5(a) shows the specular gloss at each measurement point of the decorative sheet #1, and Figure 5(b) shows the difference in gloss between adjacent measurement points.

[0061] (2) Surface roughness In accordance with JIS B 0601:1982, the arithmetic surface roughness (Ra) of the decorative sheet surface was measured at approximately 80 points along a straight line with a measurement interval of 8 mm and a measurement length of 640 mm, using a surface roughness meter (SurfCorder SE-300, manufactured by Kosaka Laboratory).

[0062] (3) Visibility The visibility of the obtained decorative sheet was evaluated according to the following criteria, as shown in Figure 11, by changing the angle (θ1) between the incident light from the light source 32 and the direction in which the viewer 34 sees the decorative sheet 30. As a result, as shown in Table 1, the standard deviation of the variation in gloss difference (%) in the measurement chart showing the relationship between the gloss difference between measurement points and adjacent measurement points for the obtained decorative sheet was 0.47%, and the visibility evaluation was ◎. ◎: The decorative sheet is tilted at a 75° angle to the front, meaning that even with a viewing angle of 150°, the design can be recognized from the front of the decorative sheet. ○: The decorative sheet is tilted at a 60° angle to the front, meaning that even with a viewing angle of 120°, the design can be recognized from the front of the decorative sheet. △: The decorative sheet is tilted at a 45° angle to the front, meaning that even with a viewing angle of 90°, the design can be recognized from the front of the decorative sheet. ×: When the decorative sheet is tilted at a 45° angle to the front, the design cannot be recognized from the front of the decorative sheet; in other words, the viewing angle is less than 90°.

[0063] [Example 2] In Example 2, a decorative sheet (decorative sheet #2) was created in the same manner as in Example 1, except that a washi paper pattern was applied to the surface as a glossy pattern by embossing, and its visibility and other properties were evaluated. Figure 6(a) shows the specular gloss at each measurement point of the decorative sheet #2, and Figure 6(b) shows the difference in gloss between adjacent measurement points. Furthermore, as shown in Table 1, in the measurement chart showing the relationship between the gloss difference between the measurement point and adjacent measurement points for the obtained decorative sheet, the standard deviation of the variation in gloss difference (%) was 0.29%, and the visibility evaluation was ○.

[0064] [Example 3] In Example 3, a decorative sheet (decorative sheet #3) was created and evaluated in the same manner as in Example 1, except that a geometric pattern was applied as a glossy pattern by embossing. Figure 7(a) shows the specular gloss at each measurement point of the obtained decorative sheet, and Figure 7(b) shows the difference in gloss between adjacent measurement points. As a result, as shown in Table 1, the standard deviation of the variation in gloss difference (%) in the measurement chart showing the relationship between the gloss difference between measurement points and adjacent measurement points for the obtained decorative sheet was 0.37%, and the visibility evaluation was ◎.

[0065] [Example 4] In Example 4, a decorative sheet was created by embossing, similar to Example 1, except that a PETG sheet (width: 2m, length: 3m) was used, and its visibility and other properties were evaluated. As a result, as shown in Table 1, the standard deviation of the variation in gloss difference (%) in the measurement chart showing the relationship between the gloss difference between measurement points and adjacent measurement points for the obtained decorative sheet was 0.45%, and the visibility evaluation was ◎.

[0066] [Comparative Example 1] In Comparative Example 1, a decorative sheet (#4 decorative sheet) was created and evaluated using an embossed roll produced by milling, in the same manner as in Example 1. As shown in Table 1, in the measurement chart showing the relationship between the gloss difference between the measurement point and adjacent measurement points for the obtained decorative sheet, the standard deviation of the variation in the gloss difference (%) was less than 0.25% (0.21%), resulting in a visibility evaluation of ×.

[0067] [Comparative Example 2] In Comparative Example 2, a decorative sheet (#5 decorative sheet) was created and evaluated using an embossed roll produced by etching (processing time: 30 minutes), in the same manner as in Example 1. As shown in Table 1, in the measurement chart showing the relationship between the gloss difference between the measurement point and adjacent measurement points for the obtained decorative sheet, the standard deviation of the variation in the gloss difference (%) was less than 0.25% (0.09%), resulting in a visibility evaluation of ×.

[0068] [Comparative Example 3] In Comparative Example 3, similar to Comparative Example 2, an embossed roll created by etching (processing time: 60 minutes) was used to create a decorative sheet (decorative sheet #6) in the same manner as in Example 1, and it was evaluated. As shown in Table 1, in the measurement chart showing the relationship between the gloss difference between the measurement point and adjacent measurement points for the obtained decorative sheet, the standard deviation of the variation in the gloss difference (%) was less than 0.25% (0.12%), resulting in a visibility evaluation of ×.

[0069] [Table 1] [Industrial applicability]

[0070] As described in detail above, the present invention is characterized in that, in a measurement chart showing the relationship between multiple measurement points and the gloss difference between adjacent measurement points, the standard deviation of the variation in gloss difference (%) is set to a value within a predetermined range, and the ratio of the maximum value to the minimum value of gloss (%) is limited to a predetermined range. Therefore, even when decorative sheets with designs featuring single colors or minimal variations in shade do not synchronize the pattern and the raised / relieved areas, it is now possible to obtain decorative sheets that allow for the recognition of a realistic design across a wide viewing angle.

[0071] Furthermore, the standard deviation of the variation in gloss level can be used as a control factor when judging the quality of the manufacturing, and as a result, it has become possible to create decorative sheets with even greater quantitative accuracy and reproducibility in terms of good design and other qualities.

[0072] Therefore, it has the potential for use in a wide range of fields, including not only single-layer decorative sheets, but also multi-layer decorative sheets combined with colored layers, optical films (light diffusion films for liquid crystal and EL light-emitting devices, polarizing films for liquid crystal devices, phase difference films for liquid crystal devices, color filters for liquid crystal and EL light-emitting devices, films for televisions using liquid crystal and EL light-emitting devices, films for projectors using liquid crystal and EL light-emitting devices, films for mobile phones using liquid crystal and EL light-emitting devices), light-shielding films, protective films, cushioning films, etc. [Explanation of symbols]

[0073] 10, 30: Decorative sheet 10a: Predetermined surface unevenness 12: Adhesive 14: Base material 32:Light source 34: Sighted person

Claims

1. A decorative sheet having a predetermined surface unevenness, The glossiness of the surface of the decorative sheet is measured at multiple measurement points m to m+n (where m and n are natural numbers of 1 or more) at predetermined lengths and at equal intervals in a straight line, in accordance with JIS Z 8741:1997, and the glossiness of the obtained n points is X １ ~X n The difference in glossiness between adjacent measurement points is defined as Y. 2 (=X) 2 -X 1 ) ~ Y n (=X) n -X n-1 In the measurement chart showing the relationship between multiple measurement points and the gloss difference obtained when this is the case, the standard deviation of the variation in gloss difference (%) is set to a value within the range of 0.29 to 1%. Furthermore, the decorative sheet is characterized in that the ratio of the maximum / minimum glossiness at the n locations is 1.5 or greater.

2. The decorative sheet according to claim 1, characterized in that the difference between the maximum and minimum values ​​of the gloss difference is within the range of 40 to 80%.

3. The decorative sheet according to claim 1 or 2, characterized in that it is a single color and exhibits a dark color such as black, dark gray, navy blue, dark purple, reddish-brown, or maroon.

4. The decorative sheet according to claim 1 or 2, characterized in that it has a glossy pattern which is one of the following: a wood grain pattern, a Japanese paper pattern, or a geometric pattern.

5. The decorative sheet according to claim 1 or 2, characterized in that the arithmetic mean roughness Ra is within the range of 5 to 20 μm with respect to the predetermined surface irregularities.

6. The decorative sheet according to claim 1 or 2, characterized in that the overall thickness is within the range of 50 to 500 μm.

7. The decorative sheet according to claim 1 or 2, characterized in that the type of decorative sheet having the predetermined surface irregularities is at least one of polyvinyl chloride resin, polyester resin, and polyolefin resin.

8. A method for manufacturing a decorative sheet having a predetermined surface unevenness, characterized by comprising the following steps (1) to (2). (1) Step of preparing a resin composition for forming the decorative sheet. (2) A step of forming a cosmetic sheet derived from the resin composition, in which, at a plurality of measurement locations m to m + n (m and n are natural numbers of 1 or more), a predetermined length, and linearly at equal intervals and at n locations, measured in accordance with JIS Z 8741:1997, and the glossiness (%) at the obtained n locations is X １ to X n Let it be, and in a measurement chart showing the relationship between a plurality of measurement locations and the glossiness difference obtained when the glossiness difference between adjacent measurement locations is Y 2 (= X 2 - X 1 ) to Y n (= X n - X n-1 ), the standard deviation of the variation in the glossiness difference (%) is set to a value within the range of 0.29 to 1%, and further, the ratio of the maximum value / minimum value of the glossiness (%) at the n locations is set to a value of 1.5 or more. A step of forming a cosmetic sheet

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