Laminate

Abstract

Provided is a laminate which includes a white protective layer and in which the appearance color of the laminate as viewed from the white protective layer side is unlikely to change even after repeated heating and cooling. A laminate according to the present invention is obtained by sequentially laminating a white protective layer and a black adhesive layer. When the laminate is disposed on a black substrate (L* value of 34.25, a* value of -0.15, b* value of -1.47) such that the adhesive layer is in contact with the black substrate, the L* value (B1-L), the a* value (B1-a), and the b* value (B1-b) of the laminate as viewed from the white protective layer side are respectively 84.00 to 88.00, -2.50 to 1.50, and -4.50 to 4.50. When the laminate is disposed on a yellow substate (L* value of 70.58, a* value of 20.80, b* value of 57.34) such that the adhesive layer is in contact with the yellow substrate, the L* value (Y1-L), the a* value (Y1-a), and the b* value (Y1-b) of the laminate as viewed from the white protective layer side are respectively 84.40 to 88.10, -2.60 to 1.50, and -4.00 to 4.50.

Description

Laminate

[0001] This invention relates to a laminate.

[0002] Printed circuit boards (PCBs) are widely used in electronic devices such as mobile phones, video cameras, and laptop computers, which are rapidly becoming smaller and more sophisticated, to integrate circuits into complex mechanisms. Furthermore, their excellent flexibility allows them to be used to connect movable parts, such as printer heads, to control units. A printed circuit board is constructed by arranging printed circuits on a base film made of glass, epoxy, paper, or phenolic material, and then placing a coverlay on top of the printed circuits. In addition, multiple solder reflow processes may be performed to arrange various electronic components on the printed circuit board.

[0003] To protect confidential information such as printed patterns contained in printed circuits placed on such printed circuit boards, a concealing protective layer is sometimes formed on top of the coverlay.

[0004] As a composition for forming such an opaque protective layer, for example, Patent Document 1 discloses a black thermosetting resin composition containing (A) an acid-modified carboxyl group-containing epoxy resin, (B) a carboxyl group-free epoxy compound, (C) an organic filler, and (D) carbon black, wherein the (D) carbon black is furnace black produced by the furnace method.

[0005] Japanese Patent Publication No. 2016-069517

[0006] In recent years, there has been a demand for white protective layers for aesthetic reasons. However, the appearance of a white protective layer when viewed from above is easily affected by the color of the coverlay placed beneath it. Furthermore, white protective layers are prone to discoloration due to heat. More specifically, multiple solder reflow processes are performed when mounting electronic components onto printed circuit boards. This means that heating and cooling are repeated. This repeated heating and cooling causes the white protective layer to discolor, resulting in a decrease in aesthetic appeal.

[0007] The present invention has been made to solve the above problem, and an object of the present invention is to provide a laminate including a white protective layer, wherein the appearance color of the laminate as viewed from the white protective layer side is less likely to change even when the laminate is repeatedly heated and cooled.

[0008] The present inventors found that in the Lab color system, when a white protective layer is disposed via a black adhesive layer on a black substrate having L ＊ value, a ＊ value and b ＊ value within predetermined ranges, and on a predetermined yellow substrate, if the L ＊ value, a ＊ value and b ＊ value of the laminate in the Lab color system as viewed from the white protective layer side fall within predetermined ranges, the appearance color of the laminate as viewed from the white protective layer side is less likely to change even when heating and cooling are repeated, and thus completed the present invention. That is, the laminate of the present invention is a laminate in which a white protective layer and an adhesive layer are sequentially laminated, the adhesive layer is a black adhesive layer, and when the laminate is disposed on a black substrate having an L ＊ value of 34.25, an a ＊ value of -0.15, and a b ＊ value of -1.47 such that the adhesive layer is in contact with the black substrate, the L ＊ value (B1-L) of the laminate as viewed from the white protective layer side is 84.00 to 88.00, the a ＊ value (B1-a) is -2.50 to 1.50, and the b ＊ value (B1-b) is -4.50 to 4.50; and when the laminate is disposed on a yellow substrate having an L ＊ value of 70.58, an a ＊ value of 20.80, and a b ＊ value of 57.34 such that the adhesive layer is in contact with the yellow substrate, the L ＊ value (Y1-L) of the laminate as viewed from the white protective layer side is 84.40 to 88.10, the a ＊ value (Y1-a) is -2.60 to 1.50, and the b ＊ value (Y1-b) is -4.00 to 4.50.

[0009] The laminate of the present invention is to be placed on a printed circuit board to conceal confidential information such as printed circuits. In the laminate of the present invention, the adhesive layer placed beneath the white protective layer is a black adhesive layer. When such a black adhesive layer is placed, the color of the coverlay of the printed circuit board affects the L of the laminate as seen from the white protective layer side. ＊ Value, a ＊ Value and b ＊ The value (hereinafter also referred to as "the visible color of the laminate when viewed from above") becomes less susceptible to influence. Furthermore, even if the laminate of the present invention is subjected to repeated heating and cooling, the visible color of the laminate when viewed from above becomes less likely to change. More specifically, when the laminate of the present invention is subjected to repeated heating and cooling, the white protective layer may turn yellow. In the laminate of the present invention, since a black adhesive layer is provided, when the white protective layer is viewed from above, it is affected by the color of the black adhesive layer, and the visible color of the white protective layer becomes less likely to change. In addition, the provision of a black adhesive layer suppresses the influence of the color of the coverlay of the printed circuit board on the visible color of the laminate when viewed from above.

[0010] The laminate of the present invention is L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ When the laminate of the present invention is placed on a black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, the L of the laminate of the present invention as seen from the white protective layer side. ＊ The value (B1-L) is between 84.00 and 88.00, a ＊ The value (B1-a) is between -2.50 and 1.50, b ＊ The value (B1-b) is between -4.50 and 4.50. Furthermore, the laminate of the present invention is L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ When the laminate of the present invention is placed on a yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, the L of the laminate of the present invention as seen from the white protective layer side. ＊ The value (Y1-L) is 84.40 to 88.10, a ＊ The value (Y1-a) is between -2.60 and 1.50, b ＊The value (Y1-b) is between -4.00 and 4.50. When the laminate of the present invention has such parameters, the visible color of the laminate when viewed from above is less likely to change even if the laminate of the present invention is repeatedly heated and cooled.

[0011] In the laminate of the present invention, L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and the L of the laminate as seen from the white protective layer side. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) is measured, and then the following heating and cooling cycle is repeated three times, after which the L of the laminate as seen from the white protective layer side is measured. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ When the value (B2-b) was measured, the L of the laminate as seen from the white protective layer side before the above heating and cooling cycle was performed. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) and the L of the laminate as seen from the white protective layer side after the above heating and cooling cycle. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (B2-b). ＊ It is preferable that ab(B2-B1) is 2.0 or less. Heating / cooling cycle: Heat to 200°C and heat for 80 seconds. Then, heat to 265°C and heat for 30 seconds. Then, let stand until it reaches room temperature. The above color difference ΔE ＊ A value of ab(B2-B1) of 2.0 or less means that the apparent color of the laminate, as viewed from above, does not change significantly before and after the heating and cooling cycle described above. In other words, the laminate of the present invention having the above parameters is a laminate whose apparent color as viewed from above does not change easily, even if heating and cooling are repeated.

[0012] In the laminate of the present invention, L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, and the L of the laminate as seen from the white protective layer side. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b) is measured, and then the following heating and cooling cycle is repeated three times. After that, the L of the laminate as seen from the white protective layer side is measured. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ When the value (Y2-b) was measured, the L of the laminate as seen from the white protective layer side before the above heating and cooling cycle was performed. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b) and the L of the laminate as seen from the white protective layer side after the above heating and cooling cycle. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y2-b). ＊ It is preferable that ab(Y2-Y1) is 2.0 or less. Heating / cooling cycle: Heat to 200°C and heat for 80 seconds. Then, heat to 265°C and heat for 30 seconds. Then, let it stand until it reaches room temperature. The above color difference ΔE ＊ The fact that ab(Y2-Y1) is 2.0 or less means that the apparent color of the laminate, as viewed from above, does not change much before and after the above heating and cooling cycle. In other words, the laminate of the present invention having the above parameters is a laminate in which the apparent color of the laminate, as viewed from above, does not change easily, even if heating and cooling are repeated.

[0013] In the laminate of the present invention, L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and then the following heating and cooling cycle is repeated three times, and the L of the laminate as seen from the white protective layer side is measured. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ Measure the value (B2-b), L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate, which has a value of 57.34, and then the following heating and cooling cycle is repeated three times, after which the L of the laminate as seen from the white protective layer side is measured. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ When the value (Y2-b) was measured, the L of the laminate placed on the black substrate after the above heating and cooling cycle was performed. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The value (B2-b) and the L of the laminate placed on the yellow substrate after the above heating and cooling cycle. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y2-b). ＊ It is preferable that ab(Y2-B2) is 1.5 or less. Heating / cooling cycle: Heat to 200°C and heat for 80 seconds. Then, heat to 265°C and heat for 30 seconds. Then, let it stand until it reaches room temperature. The above color difference ΔE ＊ The fact that ab(Y2-B2) is 1.5 or less means that even if the substrate placed beneath the laminate of the present invention has a different color, the apparent color of the laminate as seen from above after the heating and cooling cycle will be less affected by the color of the substrate. In other words, the laminate of the present invention having the above parameters is less affected by the color of the coverlay placed beneath it in terms of the apparent color of the laminate as seen from above when heating and cooling are repeated.

[0014] In the laminate of the present invention, L＊ value is 34.25, a ＊ value is -0.15, b ＊ The above laminate is placed on a black substrate having a value of -1.47 such that the above adhesive layer is in contact with the black substrate, and L of the laminate as viewed from the white protective layer side is ＊ value (B1-L), a ＊ value (B1-a) and b ＊ value (B1-b) is measured, and L ＊ value is 70.58, a ＊ value is 20.80, b ＊ The above laminate is placed on a yellow substrate having a value of 57.34 such that the above adhesive layer is in contact with the yellow substrate, and L of the laminate as viewed from the white protective layer side is ＊ value (Y1-L), a ＊ value (Y1-a) and b ＊ When value (Y1-b) is measured, L of the laminate placed on the black substrate is ＊ value (B1-L), a ＊ value (B1-a) and b ＊ value (B1-b) and L of the laminate placed on the yellow substrate ＊ value (Y1-L), a ＊ value (Y1-a) and b ＊ color difference ΔE calculated from the difference between value (Y1-b) and ＊ ab(Y1-B1) is preferably 1.5 or less. The fact that the laminate of the present invention has such parameters means that the laminate of the present invention is less susceptible to the influence of the color of a substrate disposed under the laminate.

[0015] In the laminate of the present invention, the thickness of the white protective layer is preferably 10 to 20 μm. When the thickness of the white protective layer is within the above range, the apparent color of the laminate as viewed from above is less affected by the color of the coverlay placed beneath the laminate of the present invention. Furthermore, even if the laminate of the present invention is repeatedly heated and cooled and the white protective layer turns yellow, it can still be favorably affected by the placement of the black adhesive layer, making the apparent color of the white protective layer as viewed from above less likely to change. If the thickness of the white protective layer is less than 10 μm, the white protective layer is thin, so the apparent color of the laminate as viewed from above is more easily affected by the color of the coverlay placed beneath the laminate of the present invention. If the thickness of the white protective layer exceeds 20 μm, the color of the black adhesive layer placed beneath the white protective layer is less likely to affect the apparent color of the laminate as viewed from above. Therefore, if discoloration occurs in the white protective layer, the appearance of the laminate as viewed from above is more likely to appear to have changed due to the effect of that discoloration.

[0016] In the laminate of the present invention, the thickness of the adhesive layer is preferably 1 to 10 μm. When the thickness of the adhesive layer is within this range, the apparent color of the laminate as viewed from above is less affected by the color of the coverlay placed beneath the laminate of the present invention. If the thickness of the adhesive layer is less than 1 μm, the adhesive layer is thin, so the apparent color of the laminate as viewed from above is more easily affected by the color of the coverlay placed beneath the laminate of the present invention. If the thickness of the adhesive layer exceeds 10 μm, the entire laminate becomes thicker, which may be disadvantageous for space saving.

[0017] According to the present invention, it is possible to provide a laminate that includes a white protective layer, in which the appearance of the laminate as seen from the white protective layer side does not change easily even after repeated heating and cooling.

[0018] Figure 1 is a schematic cross-sectional view showing an example of the laminate of the present invention. Figure 2 is a schematic cross-sectional view showing an example of a printed circuit board on which the laminate of the present invention is arranged.

[0019] The laminate of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments and can be modified and applied as appropriate without altering the essence of the invention.

[0020] Figure 1 is a schematic cross-sectional view showing an example of the laminate of the present invention. The laminate 10 shown in Figure 1 has a white protective layer 11 and an adhesive layer 12 laminated in that order.

[0021] In the laminate 10, the adhesive layer 12 is a black adhesive layer. As will be explained in more detail later, the laminate 10 is placed on a printed circuit board to conceal confidential information such as printed circuits. In the laminate 10, if the adhesive layer 12 placed below the white protective layer 11 is a black adhesive layer, the L of the laminate 10 as seen from the white protective layer 11 side will depend on the color of the coverlay of the printed circuit board. ＊ Value, a ＊ Value and b ＊ The value (hereinafter also referred to as "the visible color of the laminate when viewed from above") becomes less susceptible to influence. Furthermore, even if the laminate 10 is repeatedly heated and cooled, the visible color of the laminate 10 when viewed from above becomes less likely to change. More specifically, if the laminate 10 is repeatedly heated and cooled, the white protective layer 11 may change color to yellow. In the laminate 10, since a black adhesive layer is placed, when the white protective layer 11 is viewed from above, it is affected by the color of the black adhesive layer, and the visible color of the white protective layer 11 becomes less likely to change. In addition, the presence of the black adhesive layer suppresses the influence of the color of the coverlay of the printed circuit board on the visible color of the laminate 10 when viewed from above.

[0022] In the laminate 10, L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ When the laminate 10 is placed on the black substrate such that the adhesive layer 12 is in contact with the black substrate whose value is -1.47, the L of the laminate 10 as seen from the white protective layer 11 side is ＊ The value (B1-L) is between 84.00 and 88.00, a ＊ The value (B1-a) is between -2.50 and 1.50, b ＊ The value (B1-b) is between -4.50 and 4.50.＊ The value (B1-L) is more preferably 84.50 to 87.00, and even more preferably 85.00 to 86.50. ＊ The value (B1-a) is more preferably -1.00 to 1.50, and even more preferably -0.50 to 0.50. ＊ The value (B1-b) is more preferably between -3.00 and 3.00, and even more preferably between -2.00 and 2.50.

[0023] In the laminate 10, L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ When the laminate 10 is placed on the yellow substrate such that the adhesive layer 12 is in contact with the yellow substrate whose value is 57.34, the L of the laminate 10 as seen from the white protective layer 11 side ＊ The value (Y1-L) is 84.40 to 88.10, a ＊ The value (Y1-a) is between -2.60 and 0.10, b ＊ The value (Y1-b) is between -4.00 and 4.50. ＊ The value (Y1-L) is more preferably 84.50 to 87.00, and even more preferably 85.00 to 86.50. ＊ The value (Y1-a) is more preferably -1.00 to 1.50, and even more preferably -0.50 to 0.50. ＊ The value (Y1-b) is more preferably between -3.00 and 3.00, and even more preferably between -2.00 and 2.50.

[0024] In this specification, L ＊ Value, a ＊ Value and b ＊ The value refers to the value measured in accordance with geometric condition c of JIS Z 8722:2009. ＊ Value, a ＊ Value and b ＊ The value can be measured, for example, using a spectrophotometer (Konica Minolta CM-26d).

[0025] The laminate 10 is such L ＊ Value, a ＊ Value and b＊ Having a parameter for the value makes it less likely for the color of the laminate 10 to change when viewed from above, even if the laminate 10 is repeatedly heated and cooled.

[0026] In the laminate 10, L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate 10 is placed on the black substrate such that the adhesive layer 12 is in contact with the black substrate whose value is -1.47, and the L of the laminate 10 as seen from the white protective layer 11 side. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) is measured, and then the following heating and cooling cycle is repeated three times, after which the L of the laminate 10 as seen from the white protective layer 11 side is measured. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ When the value (B2-b) was measured, the L of the laminate 10 as seen from the white protective layer 11 side before the above heating and cooling cycle was performed. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) and the L of the laminate 10 as seen from the white protective layer 11 side after the above heating and cooling cycle. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (B2-b). ＊ ab(B2-B1) is preferably 2.0 or less, and more preferably 0.0 to 1.5. Heating / cooling cycle: Heat to 200°C and heat for 80 seconds. Then, heat to 265°C and heat for 30 seconds. Then, let stand until it reaches room temperature. The above color difference ΔE ＊ A value of ab(B2-B1) of 2.0 or less means that the apparent color of the laminate 10, as viewed from above, does not change much before and after the heating and cooling cycle described above. In other words, a laminate 10 having the above parameters can be said to be a laminate in which the apparent color of the laminate 10, as viewed from above, does not change easily, even if heating and cooling are repeated.

[0027] In the laminate 10, L＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate 10 is placed on the yellow substrate such that the adhesive layer 12 is in contact with the yellow substrate whose value is 57.34, and the L of the laminate 10 as seen from the white protective layer 11 side. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b) is measured, and then the following heating and cooling cycle is repeated three times. After that, the L of the laminate 10 as seen from the white protective layer 11 side is measured. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ When the value (Y2-b) was measured, the L of the laminate 10 as seen from the white protective layer 11 side before the above heating and cooling cycle was performed. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b) and the L of the laminate 10 as seen from the white protective layer 11 side after the above heating and cooling cycle. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y2-b). ＊ ab(Y2-Y1) is preferably 2.0 or less, and more preferably 0.0 to 1.5. Heating / cooling cycle: Heat to 200°C and heat for 80 seconds. Then, heat to 265°C and heat for 30 seconds. Then, let stand until it reaches room temperature. The above color difference ΔE ＊ The fact that ab(Y2-Y1) is 2.0 or less means that the apparent color of the laminate 10, as viewed from above, does not change much before and after the heating and cooling cycle. In other words, a laminate 10 having the above parameters can be said to be a laminate in which the apparent color of the laminate 10 as viewed from above does not change easily, even if heating and cooling are repeated.

[0028] In the laminate 10, L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊The laminate 10 is placed on the black substrate so that the adhesive layer 12 is in contact with the black substrate, which has a value of -1.47. Then, the following heating and cooling cycle is repeated three times, and the L of the laminate 10 as seen from the white protective layer 11 side is measured. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ Measure the value (B2-b), L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate 10 is placed on the yellow substrate such that the adhesive layer 12 is in contact with the yellow substrate, which has a value of 57.34. Then, the following heating and cooling cycle is repeated three times, and the L of the laminate 10 as seen from the white protective layer 11 side is measured. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ When the value (Y2-b) was measured, the L of the laminate 10 placed on the black substrate after the above heating and cooling cycle was performed. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The value (B2-b) and the L of the laminate 10 placed on the yellow substrate after the above heating and cooling cycle. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y2-b). ＊ ab(Y2-B2) is preferably 1.5 or less, and more preferably 0.0 to 1.0. Heating / cooling cycle: Heat to 200°C and heat for 80 seconds. Then, heat to 265°C and heat for 30 seconds. Then, let stand until it reaches room temperature. The above color difference ΔE ＊ A value of ab(Y2-B2) of 1.5 or less means that even if the substrate placed beneath the laminate 10 has a different color, the apparent color of the laminate 10 as seen from above after the heating and cooling cycle will not be significantly affected by the substrate's color. In other words, a laminate 10 having the above parameters is less affected by the color of the coverlay placed beneath it in terms of its apparent color as seen from above when heating and cooling are repeated.

[0029] In the laminate 10, L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and the L of the laminate as seen from the white protective layer side. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ Measure the value (B1-b), L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, and the L of the laminate as seen from the white protective layer side. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ When the value (Y1-b) was measured, the L of the laminated material placed on the black substrate was measured. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) and the L of the laminate arranged on the yellow substrate. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y1-b). ＊ ab(Y1-B1) is preferably 1.5 or less, and more preferably 0.00 to 1.00. The above color difference ΔE ＊ The fact that ab(Y1-B1) is 1.5 or less indicates that the laminate 10 is less affected by the color of the substrate placed beneath it.

[0030] The following describes in detail each component of the laminate of the present invention.

[0031] (White protective layer) In the laminate of the present invention, the white protective layer may contain a resin and a white pigment.

[0032] The resin is not particularly limited, but examples include thermoplastic resin compositions, thermosetting resin compositions, and active energy ray curable compositions.

[0033] The thermoplastic resin composition is not particularly limited, but styrene-based resin compositions, vinyl acetate-based resin compositions, polyester-based resin compositions, polyethylene-based resin compositions, polypropylene-based resin compositions, imide-based resin compositions, and acrylic-based resin compositions can be used. The thermosetting resin composition is not particularly limited, but phenol-based resin compositions, epoxy-based resin compositions, urethane-based resin compositions, melamine-based resin compositions, and alkyd-based resin compositions can be used. The active energy ray-curable composition is not particularly limited, but for example, polymerizable compounds having at least two (meth)acryloyloxy groups in the molecule can be used. These compositions may be used individually or in combination of two or more.

[0034] In the laminate of the present invention, the resin content in the white protective layer is preferably 15 to 40 wt%.

[0035] The white pigment is not particularly limited, but it is preferably at least one selected from the group consisting of titanium dioxide, zinc oxide, sodium hydroxide, silica, barium sulfate, talc, mica, glass flakes, boron nitride (BN), calcium carbonate, aluminum hydroxide, titanate (potassium titanate, etc.), barium sulfate, alumina, kaolin, clay, titanium dioxide, zinc oxide, zinc sulfide, lead titanate, zircon oxide, antimony oxide, and magnesium oxide. Among these, titanium dioxide is more preferred. Rutile-type titanium dioxide particles may be used as the titanium dioxide. These white pigments can suitably impart whiteness to the white protective layer.

[0036] The average particle size of the above white pigment is preferably 10 μm or less, and more preferably 0.1 to 5 μm. If the average particle size of the white pigment exceeds 10 μm, color unevenness is likely to occur. Also, if the average particle size of the white pigment is less than 0.1 μm, the particles tend to aggregate, leading to poor dispersion and color unevenness. In this specification, the average particle size refers to the particle size of the average particle size D50 (median diameter) based on the number of particles, measured by laser diffraction and scattering.

[0037] In the laminate of the present invention, the white protective layer may further contain a curing accelerator, a tackifier, an antioxidant, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, a viscosity modifier, and an anti-blocking agent. Silica can be used as the filler. Aluminum hydroxide can be used as the flame retardant.

[0038] Furthermore, the laminate of the present invention may contain pigments or dyes other than white pigments to adjust the color of the white protective layer. Examples of such pigments include yellow pigments, red pigments, and orange pigments. Examples of yellow pigments include bismuth vanadate, titanium-nickel-antimony oxide, titanium-nickel-barium oxide, titanium-chromium-antimony oxide, titanium-chromium-tungsten oxide, zinc-iron oxide, vanadium zirconium yellow, vanadium tin yellow, praseodymium yellow, barium chromate, and calcium chromate. Examples of red pigments include iron oxide, quinacridone, naphthol, azo compounds, and diketopyrrolopyrrole.

[0039] In the laminate of the present invention, the content of the white pigment in the white protective layer is preferably 20 to 50 wt%.

[0040] In the laminate of the present invention, the thickness of the white protective layer is preferably 10 to 20 μm, and more preferably 12 to 18 μm. When the thickness of the white protective layer is within the above range, the apparent color of the laminate as viewed from above is less affected by the color of the coverlay placed beneath the laminate of the present invention. When the thickness of the white protective layer is less than 10 μm, the white protective layer is thin, so the apparent color of the laminate as viewed from above is more easily affected by the color of the coverlay placed beneath the laminate of the present invention. When the thickness of the white protective layer exceeds 20 μm, the color of the black adhesive layer placed beneath the white protective layer is less affected by the apparent color of the laminate as viewed from above. Therefore, if discoloration occurs in the white protective layer, the apparent color of the laminate as viewed from above is more likely to appear to have changed due to the effect of that discoloration.

[0041] In the laminate of the present invention, the white protective layer is placed in a colorimeter, and the L of the white protective layer as seen from above.＊ The value is between 95 and 85, a ＊ The value is between -2.00 and 5.00, and b ＊ A value between -1.00 and 7.00 is preferable. A spectrophotometer (Konica Minolta, CM-26d) can be used as the colorimeter.

[0042] (Adhesive layer) In the laminate of the present invention, the adhesive layer may contain an adhesive resin and a black pigment.

[0043] The adhesive resin is not particularly limited, but may consist of thermoplastic resin compositions such as styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, imide resin compositions, amide resin compositions, and acrylic resin compositions, or thermosetting resin compositions such as phenol resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, and alkyd resin compositions. The adhesive layer may contain only one of these materials, or it may contain two or more.

[0044] In the laminate of the present invention, the content of adhesive resin in the adhesive layer is preferably 70 to 95 wt%.

[0045] The black pigment is not particularly limited, but it is preferably at least one selected from the group consisting of carbon black, black iron oxide, copper-chromium oxide, copper-chromium-zinc oxide, iron-manganese oxide, iron-cobalt-chromium oxide, and copper-chromium-manganese oxide. Among these, carbon black is more preferred.

[0046] The average particle size of the black pigment is preferably 10 μm or less, and more preferably 0.01 to 3 μm. If the average particle size of the black pigment exceeds 10 μm, color unevenness is likely to occur. Also, if the average particle size of the black pigment is less than 0.01 μm, the particles tend to aggregate, leading to poor dispersion and color unevenness.

[0047] In the laminate of the present invention, the content of the black pigment in the adhesive layer is preferably 5 to 30 wt%.

[0048] If conductivity is desired in the adhesive layer, a conductive filler may be added to the adhesive layer. The conductive filler is not particularly limited and can be silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-plated copper powder, polymer fine particles, glass beads, or other particles coated with metal.

[0049] The adhesive layer may contain, as needed, curing accelerators, tackifiers, antioxidants, plasticizers, UV absorbers, defoamers, leveling agents, fillers, flame retardants, viscosity modifiers, etc.

[0050] Furthermore, the laminate of the present invention may contain pigments or dyes other than black pigment in order to adjust the color of the adhesive layer.

[0051] In the laminate of the present invention, the thickness of the adhesive layer is preferably 1 to 10 μm, and more preferably 2 to 5 μm. When the thickness of the adhesive layer is within the above range, the apparent color of the laminate as viewed from above is less affected by the color of the coverlay placed beneath the laminate of the present invention. If the thickness of the adhesive layer is less than 1 μm, the adhesive layer is thin, so the apparent color of the laminate as viewed from above is more easily affected by the color of the coverlay placed beneath the laminate of the present invention. If the thickness of the adhesive layer exceeds 10 μm, the entire laminate becomes thicker, which may be disadvantageous for space saving.

[0052] In the laminate of the present invention, the adhesive layer is placed in a colorimeter, and the L of the adhesive layer as seen from above. ＊ The value is 20 to 30, a ＊ The value is between -2.00 and 2.00, and b ＊ A value between -3.00 and 3.00 is preferable. A spectrophotometer (Konica Minolta, CM-26d) can be used as the colorimeter.

[0053] The laminate of the present invention is arranged on a printed circuit board. Such embodiments will be described in detail below with reference to the drawings.

[0054] Figure 2 is a schematic cross-sectional view showing an example of a printed circuit board on which the laminate of the present invention is arranged. As shown in Figure 2, the laminate 10 is arranged on top of the printed circuit board 20.

[0055] The printed circuit board 20 comprises a base film 21, a printed circuit 22 arranged on the base film 21, and a coverlay 23 arranged to cover the printed circuit 22.

[0056] In Figure 2, the laminate 10 is positioned on the printed circuit board 20 such that the adhesive layer 12 of the laminate 10 is in contact with the coverlay 23 of the printed circuit board 20, and the white protective layer 11 is located on top of the printed circuit 22.

[0057] The white protective layer 11 is positioned on top of the printed circuit 22, so that it can conceal the pattern of the printed circuit 22.

[0058] Furthermore, the printed circuit board 20 undergoes multiple solder reflow processes, and electronic components (not shown) are placed on it. In other words, the printed circuit board 20 is repeatedly heated and cooled.

[0059] The laminate 10 is arranged on the printed circuit board 20, and even if the reflow process described above is repeated (i.e., even if heating and cooling are repeated), the appearance of the laminate 10 when viewed from above does not easily change in color. Therefore, the overall aesthetics of the printed circuit board 20 on which the laminate 10 is arranged can be maintained.

[0060] In the printed circuit board 20, it is preferable that both the base film 21 and the coverlay 23 are made of engineering plastic. Examples of such resins include polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, polyimide, polyimideamide, polyetherimide, and polyphenylene sulfide (PPS).

[0061] In the printed circuit board 20, the printed circuit 22 can be made of ordinary circuit materials such as copper.

[0062] Furthermore, the base film 21 and the printed circuit 22 may be bonded together with an adhesive, or they may be joined without using an adhesive, similar to so-called adhesive-free copper-clad laminates. The coverlay 23 may also be made by bonding multiple flexible insulating films together with an adhesive, or it may be formed by a series of methods such as coating, drying, exposure, development, and heat treatment of a photosensitive insulating resin.

[0063] The color of the coverlay 23 is not particularly limited, but for example, the color of the surface of the printed circuit board is L ＊ The value is between 20 and 40, a ＊ The value is between -2.00 and 2.00, and b ＊ The value may be between -3.00 and 3.00, L ＊ The value is between 60 and 80, a ＊ The value is between 10 and 30, b ＊ The value may be between 40 and 70.

[0064] Conventional methods can be used to attach the laminate 10 to the printed circuit board 20. For example, the laminate 10 may be placed on the printed circuit board 20 so that the adhesive layer 12 of the laminate 10 is in contact with the coverlay 23 of the printed circuit board 20, and then heat-pressed at 150 to 200°C, 2 to 5 MPa, and for 1 to 60 minutes.

[0065] This specification contains the following information:

[0066] (1) This disclosure is a laminate in which a white protective layer and an adhesive layer are sequentially laminated, wherein the adhesive layer is a black adhesive layer, L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ When the laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, the L of the laminate as seen from the white protective layer side ＊ The value (B1-L) is between 84.00 and 88.00, a ＊ The value (B1-a) is between -2.50 and 1.50, b ＊ The value (B1-b) is between -4.50 and 4.50, L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊When the laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, the L of the laminate as seen from the white protective layer side. ＊ The value (Y1-L) is 84.40 to 88.10, a ＊ The value (Y1-a) is between -2.60 and 1.50, b ＊ This laminate is characterized by having a value (Y1-b) between -4.00 and 4.50.

[0067] This disclosure (2) is L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and the L of the laminate as seen from the white protective layer side. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) is measured, and then the following heating and cooling cycle is repeated three times, after which the L of the laminate as seen from the white protective layer side is measured. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ When the value (B2-b) was measured, the L of the laminate as seen from the white protective layer side before the above heating and cooling cycle was performed. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) and the L of the laminate as seen from the white protective layer side after the above heating and cooling cycle. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (B2-b). ＊ The laminate according to disclosure (1) wherein ab(B2-B1) is 2.0 or less. Heating and cooling cycle: Heat to 200°C and heat at that temperature for 80 seconds. Then, heat to 265°C and heat at that temperature for 30 seconds. Then, let it stand until it reaches room temperature.

[0068] This disclosure (3) is L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, and the L of the laminate as seen from the white protective layer side. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b) is measured, and then the following heating and cooling cycle is repeated three times. After that, the L of the laminate as seen from the white protective layer side is measured. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ When the value (Y2-b) was measured, the L of the laminate as seen from the white protective layer side before the above heating and cooling cycle was performed. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b) and the L of the laminate as seen from the white protective layer side after the above heating and cooling cycle. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y2-b). ＊ The laminate is as described in (1) or (2) of this disclosure, wherein ab(Y2-Y1) is 2.0 or less. Heating / cooling cycle: Heat to 200°C and heat at that temperature for 80 seconds. Then, heat to 265°C and heat at that temperature for 30 seconds. Then, let it stand until it reaches room temperature.

[0069] This disclosure (4) is L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and then the following heating and cooling cycle is repeated three times, and the L of the laminate as seen from the white protective layer side is measured. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ Measure the value (B2-b), L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate, which has a value of 57.34, and then the following heating and cooling cycle is repeated three times, after which the L of the laminate as seen from the white protective layer side is measured. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ When the value (Y2-b) was measured, the L of the laminate placed on the black substrate after the above heating and cooling cycle was performed. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The value (B2-b) and the L of the laminate placed on the yellow substrate after the above heating and cooling cycle. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y2-b). ＊ The laminate is one of the present disclosures (1) to (3) wherein ab(Y2-B2) is 1.5 or less. Heating and cooling cycle: Heat to 200°C and heat at that temperature for 80 seconds. Then, heat to 265°C and heat at that temperature for 30 seconds. Then, let it stand until it reaches room temperature.

[0070] This disclosure (5) is L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and the L of the laminate as seen from the white protective layer side. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ Measure the value (B1-b), L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, and the L of the laminate as seen from the white protective layer side. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ When the value (Y1-b) was measured, the L of the laminated material placed on the black substrate was measured. ＊ Value (B1-L), a＊ Value (B1-a) and b ＊ The value (B1-b) and the L of the laminate arranged on the yellow substrate. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y1-b). ＊ The laminate is one of the present disclosures (1) to (4) wherein ab(Y1-B1) is 1.5 or less.

[0071] Disclosure (6) is a laminate according to any one of Disclosures (1) to (5), wherein the thickness of the white protective layer is 10 to 20 μm.

[0072] Disclosure (7) is a laminate according to any one of Disclosures (1) to (6), wherein the thickness of the adhesive layer is 1 to 10 μm.

[0073] The following are examples illustrating the present invention in more detail, but the present invention is not limited to these examples.

[0074] (Example 1) A composition for a white protective layer was prepared by mixing the resin, white pigment, other pigments, and other components in the proportions shown in Table 1. Note that the composition values ​​in Table 1 represent parts by weight. The resin used for the white protective layer in Table 1 had the following properties: Polyester resin: Mn: 16,000, Tg: 15°C, Acid value: 17 KOH mg / g Epoxy resin: Epoxy value: 280 KOH mg / g

[0075] Next, a white protective layer composition was applied to the transfer film, and the film was heated in an electric oven at 130°C for 3 minutes to produce a white protective layer with a thickness of 12 μm.

[0076] Next, pigments were mixed with adhesive resin in the proportions shown in Table 1 to prepare adhesive layer compositions.

[0077] Next, an adhesive layer composition was applied onto the white protective layer to form an adhesive layer with a thickness of 3 μm.

[0078] The laminate according to Example 1 was manufactured through the above process.

[0079]

[0080] Laminates according to Examples 2 to 11 and Comparative Examples 1 to 3 were manufactured in the same manner as in Example 1, except that the composition and thickness of the white adhesive layer and adhesive layer were changed to the values ​​shown in Tables 1 and 2. Note that the composition values ​​in Table 2 refer to "parts by weight".

[0081]

[0082] (Measurement of the color of the laminate when placed on a black substrate) L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ Each laminate was placed on a black substrate so that the adhesive layer was in contact with the black substrate, which had a value of -1.47, and was thermocompressed at 170°C, 3 MPa, and for 30 minutes. Subsequently, the L of each laminate as seen from the white protective layer side was measured using a spectrophotometer (Konica Minolta, CM-26d). ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) was measured. The results are shown in Tables 1 and 2.

[0083] Furthermore, after placing each laminate on the black substrate described above, the following heating and cooling cycle is repeated three times, and then the L of each laminate as seen from the white protective layer side is... ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The value (B2-b) was measured. Heating / cooling cycle: The temperature was raised to 200°C and heated for 80 seconds. Then, the temperature was raised to 265°C and heated for 30 seconds. After that, it was allowed to stand until it reached room temperature. The results are shown in Tables 1 and 2.

[0084] (Measurement of the color of the laminate when placed on a yellow substrate) L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminates according to each example and comparative example were placed on a yellow substrate so that the adhesive layer was in contact with the yellow substrate, which had a value of 57.34, and were heat-pressed at 170°C, 3 MPa, and for 30 minutes. After that, the L of each laminate as seen from the white protective layer side was measured. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊The value (Y1-b) was measured. The results are shown in Tables 1 and 2.

[0085] Furthermore, after placing each laminate on the yellow substrate described above, the following heating and cooling cycle is repeated three times, and then the L of each laminate as seen from the white protective layer side is... ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The value (Y2-b) was measured. The results are shown in Tables 1 and 2. Heating / cooling cycle: The temperature was raised to 200°C and heated for 80 seconds. Then, the temperature was raised to 265°C and heated for 30 seconds. After that, it was left to stand until it reached room temperature.

[0086] (Calculation of color difference) L of each layer ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) and L ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ Color difference ΔE from the value (B2-b) ＊ ab(B2-B1) was calculated for each layer. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b), and L ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ Color difference ΔE from the value (Y2-b) ＊ ab(Y2-Y1) was calculated for each laminate. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) and L ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ Color difference ΔE from the value (Y1-b) ＊ ab(Y1-B1) was calculated for each laminate. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The value (B2-b) and L ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ Color difference ΔE from the value (Y2-b) ＊ab(Y2-B2) was calculated. The results are shown in Tables 1 and 2.

[0087] As shown in Table 1, the laminates according to each embodiment have a color difference ΔE ＊ ab(B2-B1) is 2.0 or less, and the color difference ΔE ＊ ab(Y2-Y1) is 2.0 or less, and the color difference ΔE ＊ ab(Y2-B2) was 1.5 or less. In other words, it was found that the laminates according to each embodiment did not change in appearance when viewed from above, even after repeated heating and cooling.

[0088] Furthermore, as shown in Table 2, it was found that the laminates in each comparative example where the adhesive layer was not black were prone to changes in the visible color of the laminate when viewed from above after repeated heating and cooling.

[0089] Furthermore, the color difference ΔE listed in Tables 1 and 2 ＊ ab(Y1-B1) and color difference ΔE ＊ From the values ​​of ab(Y2-B2), it was found that in each embodiment, the visible color of the laminate when viewed from above is less affected by the color of the coverlay placed beneath the laminate.

[0090] 10 Laminate 11 White protective layer 12 Adhesive layer 20 Printed circuit board 21 Base film 22 Printed circuit 23 Coverlay

Claims

1. A laminate obtained by sequentially laminating a white protective layer and an adhesive layer, wherein the adhesive layer is a black adhesive layer, and when the laminate is placed on a black substrate having an L ＊ value of 34.25, an a ＊ value of -0.15, and a b ＊ value of -1.47 such that the adhesive layer is in contact with the black substrate, an L ＊ value (B1-L) of the laminate as viewed from the white protective layer side is 84.00 to 88.00, an a ＊ value (B1-a) is -2.50 to 1.50, and a b ＊ value (B1-b) is -4.50 to 4.50; and when the laminate is placed on a yellow substrate having an L ＊ value of 70.58, an a ＊ value of 20.80, and a b ＊ value of 57.34 such that the adhesive layer is in contact with the yellow substrate, an L ＊ value (Y1-L) of the laminate as viewed from the white protective layer side is 84.40 to 88.10, an a ＊ value (Y1-a) is -2.60 to 1.50, and a b ＊ value (Y1-b) is -4.00 to 4.

50. A laminate characterized by the above.

2. L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and the L of the laminate as seen from the white protective layer side. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) is measured, and then the following heating and cooling cycle is repeated three times, after which the L of the laminate as seen from the white protective layer side is measured. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ When the value (B2-b) was measured, the L of the laminate as seen from the white protective layer side before the heating and cooling cycle was performed. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) and the L of the laminate as seen from the white protective layer side after the heating and cooling cycle. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (B2-b). ＊ The laminate according to claim 1, wherein ab(B2-B1) is 2.0 or less. Heating / cooling cycle: Heat to 200°C and heat at that temperature for 80 seconds. Then, heat to 265°C and heat at that temperature for 30 seconds. Then, let stand until it reaches room temperature.

3. L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, and the L of the laminate as seen from the white protective layer side. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b) is measured, and then the following heating and cooling cycle is repeated three times, after which the L of the laminate as seen from the white protective layer side is measured. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ When the value (Y2-b) was measured, the L of the laminate as seen from the white protective layer side before the heating and cooling cycle was performed. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The value (Y1-b) and the L of the laminate as seen from the white protective layer side after the heating and cooling cycle. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y2-b). ＊ The laminate according to claim 1 or 2, wherein ab(Y2-Y1) is 2.0 or less. Heating / cooling cycle: Heat to 200°C and heat at that temperature for 80 seconds. Then, heat to 265°C and heat at that temperature for 30 seconds. Then, let stand until it reaches room temperature.

4. L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and then the following heating and cooling cycle is repeated three times, and the L of the laminate as seen from the white protective layer side is then measured. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ Measure the value (B2-b), L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, and then the following heating and cooling cycle is repeated three times, after which the L of the laminate as seen from the white protective layer side is measured. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ When the value (Y2-b) was measured, the L of the laminate placed on the black substrate after the heating and cooling cycle was performed. ＊ Value (B2-L), a ＊ Values ​​(B2-a) and b ＊ The value (B2-b) and the L of the laminate placed on the yellow substrate after the heating and cooling cycle. ＊ Value (Y2-L), a ＊ Values ​​(Y2-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y2-b). ＊ A laminate according to any one of claims 1 to 3, wherein ab(Y2-B2) is 1.5 or less. Heating / cooling cycle: Heat to 200°C and heat at that temperature for 80 seconds. Then, heat to 265°C and heat at that temperature for 30 seconds. Then, let stand until it reaches room temperature.

5. L ＊ The value is 34.25, a ＊ The value is -0.15, b ＊ The laminate is placed on the black substrate such that the adhesive layer is in contact with the black substrate whose value is -1.47, and the L of the laminate as seen from the white protective layer side. ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ Measure the value (B1-b), L ＊ The value is 70.58, a ＊ The value is 20.80, b ＊ The laminate is placed on the yellow substrate such that the adhesive layer is in contact with the yellow substrate whose value is 57.34, and the L of the laminate as seen from the white protective layer side. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ When the value (Y1-b) was measured, the L of the laminate arranged on the black substrate ＊ Value (B1-L), a ＊ Value (B1-a) and b ＊ The value (B1-b) and the L of the laminate arranged on the yellow substrate. ＊ Value (Y1-L), a ＊ Values ​​(Y1-a) and b ＊ The color difference ΔE is calculated from the difference with the value (Y1-b). ＊ The laminate according to any one of claims 1 to 4, wherein ab(Y1-B1) is 1.5 or less.

6. The laminate according to any one of claims 1 to 5, wherein the thickness of the white protective layer is 10 to 20 μm.

7. The laminate according to any one of claims 1 to 6, wherein the thickness of the adhesive layer is 1 to 10 μm.

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