JP4586480B2 - WHITE TRANSFER SHEET AND OPTICAL SHEET PROVIDED WITH WHITE LAYER - Google Patents

Description

The present invention relates to a white transfer sheet capable of transferring and forming a white layer having a high reflectance and a fine pattern on the order of microns (μm = 10 ⁻⁶ m) so as to be used for an optical product, and The present invention relates to an optical sheet provided with a white layer transferred by.

  Conventionally, as a white transfer sheet capable of transferring and forming a white layer, there is, for example, a correction tape as shown in Patent Documents 1 and 2. This is applied to the technique of applying a white tape to correct a part written with pen or ink.

A general transfer sheet technique is also applied to transfer formation of an optical working surface in an optical product. The optical working surface can accurately form a micron (μm = 10 ⁻⁶ m) order fine pattern for causing a desired optical action such as diffraction and reflection, has little light absorption, and has a higher light reflectance. It is desirable to have. From the viewpoint of low light absorption, the optical working surface is limited to white. Further, from the viewpoint of realizing a high light reflectance, the optical working surface is preferably thicker (preferably 10 microns or more).
Japanese Patent No. 3274198 Japanese Utility Model Publication No. 5-65559

  In order to transfer and form a white and thick optical working surface, it is necessary to increase the thickness of the white layer which is the pigment layer of the white transfer sheet. However, it becomes more difficult for the white transfer sheet to transfer a fine pattern as the thickness of the white layer increases. Therefore, in the prior art, it is impossible to accurately form a micron-order fine pattern and transfer and form a white layer having a thickness of 10 microns or more. For this reason, in the optical product according to the prior art, any of the optical performance, light reflectance, and pattern forming ability in the white layer must be sacrificed, and all of the excellent optical performance, light reflectance, and pattern forming ability are obtained. There is a problem that none has a white layer.

  The present invention has been made in view of such circumstances, a white transfer sheet capable of accurately forming a micron-order fine pattern and transferring a white layer having high light reflectance, and An object of the present invention is to provide an optical sheet provided with a white layer transferred by the transfer.

  In order to achieve the above object, the present invention takes the following measures.

That is, the invention of claim 1 is a white transfer sheet in which a white transfer layer is disposed on a base sheet. Here, as the white transfer layer, a binder made of ethylene vinyl acetate containing 30% or less vinyl acetate by weight and having a melt flow rate of 10 g / min or more, and 1.5 times the volume ratio of the binder. It is formed so as to have a thickness of 10 × 10 ⁻⁶ m or more by mixing 4 or less times as much titanium dioxide .

  The invention according to claim 2 is an optical sheet provided with a white layer transferred by the white transfer sheet according to claim 1.

  According to the present invention, a white transfer sheet capable of accurately forming a micron-order fine pattern and transferring a white layer having a high light reflectance, and a white layer transferred thereby are provided. An optical sheet can be realized.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a side view showing an example of a white transfer sheet according to an embodiment of the present invention.

  That is, the white transfer sheet 10 according to the embodiment has a white transfer layer 14 disposed on a base sheet 12. As the material for the base sheet 12, PP (polypropylene), PET (polyethylene terephthalate), PE (polyester), or the like well known in the technical field is used.

  On the other hand, as the white transfer layer 14, a binder resin made of EVA (ethylene vinyl acetate) containing 30% or less by weight of vinyl acetate and having a melt flow rate of 10 g or more per minute, and a volume more than this binder resin. A white pigment having a ratio of 1 to 4 times is mixed. As the white pigment, titanium dioxide, barium sulfate, magnesium oxide and the like well known in the art are used.

By mixing the binder resin and the white pigment at such a mixing ratio, the white transfer layer 14 having a thickness of 10 × 10 ⁻⁶ m or more can be formed. The binder resin is not limited to EVA, and another resin may be used. However, a binder resin that is not hard and has a small molecular weight is preferable.

  It should be noted that a dispersing agent, wax, or the like may be added as appropriate to the white transfer layer 14 formed in this manner to stabilize the white transfer layer 14. Surfactants and surface smoothing agents are also used for the dispersants and waxes used in such applications, as is well known in the art.

  Next, the operation of the white transfer sheet according to the embodiment configured as described above will be described with reference to FIG.

As shown in case 9 of FIG. 2, PP is used as a base sheet 12, binder resin made of EVA containing 28% vinyl acetate by weight and a melt flow rate of 40 g per minute, and this binder resin Was mixed with a white pigment made of titanium dioxide having a volume ratio of 4 to form a white transfer layer 14 having a thickness of 13 × 10 ⁻⁶ m.

When such a white transfer sheet 10 was used to transfer and form a white layer, it was possible to realize an extremely high reflectance of 91% in total light reflectance at a wavelength of 545 nm. In addition, a fine stripe pattern with a pitch of 200 × 10 ⁻⁶ m (200 microns) and a width of 100 × 10 ⁻⁶ m (100 microns) can be accurately formed on the white layer. did it.

Also, as shown in case 11 of FIG. 2, a silicon-treated PET is used as a base sheet 12, a binder resin made of EVA containing 28% vinyl acetate by weight and a melt flow rate of 40 g per minute; The binder resin and a white pigment made of titanium dioxide having a volume ratio of 1: 1 were mixed to form a white transfer layer 14 having a thickness of 18 × 10 ⁻⁶ m.

When such a white transfer sheet 10 was used to transfer and form a white layer in the same manner, it was possible to realize a very high reflectance with a total light reflectance of 87% at a wavelength of 545 nm. Moreover, a fine stripe pattern with a pitch of 200 × 10 ⁻⁶ m (200 microns) and a width of 100 × 10 ⁻⁶ m (100 microns) is accurately formed on the white layer. I was able to.

Further, as the white transfer layer 14, a binder resin made of EVA containing 30% or less vinyl acetate by weight and having a melt flow rate of 10 g or more per minute, and a volume ratio of 1 to 4 times the binder resin. In the case of the cases 6 to 8 and 12 shown in FIG. 2 that match the condition of mixing a white pigment of twice or less, a white transfer layer 14 having a thickness of 10 × 10 ⁻⁶ m or more can be formed. Furthermore, when a white layer was similarly transferred and formed using each of the white transfer sheets 10, it was possible to realize an extremely high reflectivity in which the total light reflectance at a wavelength of 545 nm exceeded 80%. A fine stripe pattern with a pitch of 200 × 10 ⁻⁶ m (200 microns) and a width of 100 × 10 ⁻⁶ m (100 microns) is accurately formed on the white layer. I was able to.

  Even if the white layer is transferred and formed using the white transfer sheet 10 including the white transfer layer 14 formed under the conditions of cases 1 to 5, 10, 13, and 14 shown in FIG. The pattern could not be formed accurately. Cases 1 to 5 are binder resins made of EVA containing 28% vinyl acetate by weight and having a melt flow rate of 40 g per minute, but the volume ratio of the white pigment to the binder resin is less than 1 time. . In contrast, the case 10 is larger than four times. In cases 13 and 14, the volume ratio of the white pigment to the binder resin is 1 time, but the binder resin contains 30% or more vinyl acetate by weight, and the melt flow rate is 10 g or less per minute. .

  As described above, in the white transfer sheet according to the present embodiment, a fine pattern on the order of microns is accurately formed and a white layer having high light reflectance is transferred and formed by the above-described action. Is possible. Further, by transferring and forming a white layer using this white transfer sheet, it is possible to realize an optical sheet provided with a white layer having excellent optical performance and light reflectance.

  The best mode for carrying out the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to such a configuration. Within the scope of the invented technical idea of the scope of claims, a person skilled in the art can conceive of various changes and modifications. The technical scope of the present invention is also applicable to these changes and modifications. It is understood that it belongs to.

FIG. 3 is an elevation view illustrating an example of a white transfer sheet according to an embodiment of the present invention. The figure which shows the formation conditions of a white transfer layer, and the propriety of pattern formation.

Explanation of symbols

  10 ... White transfer sheet, 12 ... Base sheet, 14 ... White transfer layer

Claims (2)

A white transfer sheet having a white transfer layer disposed on a base sheet,
A binder comprising ethylene vinyl acetate containing 30% or less vinyl acetate by weight and having a melt flow rate of 10 g / min or more, and titanium dioxide having a volume ratio of 1.5 to 4 times that of the binder; A white transfer sheet in which the white transfer layer is formed so as to have a thickness of 10 × 10 ⁻⁶ m or more.   An optical sheet provided with a white layer transferred by the white transfer sheet according to claim 1.

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