JPH0493979A - Production of hologram forming sheet - Google Patents

Abstract

PURPOSE:To enhance working efficiency and to lessen an energy loss as well as to enhance the mechinability of the formed holograms and to reduce the cost of production by forming hologram patterns on a polyethylene (PE) resin having >=90 deg.C Vicat softening point simultaneously with pressing, cooling and sheet molding by a cooling roll. CONSTITUTION:The PE resin 3 which is melted and extruded in the form of a thin film from a T die 2 is pressed and cooled by the cooling roll 4 disposed with a hologram relief original plate on the peripheral surface and is thereby integrally formed with the hologram patterns simultaneously with the sheet molding. Since this PE resin 3 has >= 90 deg.C Vicat softening point, the formed hologram patterns are excellent in the adaptability to vapor deposition and are highly resistant to flawing, erasing, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a hologram-forming sheet, and particularly to a method for manufacturing a hologram-forming sheet in which sheet molding and hologram formation are performed simultaneously by extrusion molding.

[Conventional technology]

In recent years, holograms have been reproduced using so-called hologram relief, which records interference fringes of light as a concavo-convex pattern on the surface of a recording material. This hologram copy is
Embossing was performed on a resin sheet using a stamper on which a hologram relief was formed, and metal vapor deposition was performed on the uneven patterned surface of the resin.

[Problem to be solved by the invention]

However, the formation of a hologram pattern on a resin sheet is
- Since the modified thermoplastic resin sheet is reheated and embossed, there are problems in that it requires a large number of steps and has low working efficiency, as well as high energy loss and not suitable for mass production. In order to solve these problems, a method for producing a hologram-forming sheet in which a surface relief hologram is obtained by extrusion molding technology has been disclosed (Japanese Patent Application Laid-Open No. 191872/1987). However, if the hardness of the resin sheet on which the hologram pattern is formed is low, the hologram pattern may be damaged or lost during hologram formation or secondary processing, resulting in poor machining suitability. Further, if the heat resistance of the resin sheet on which the hologram pattern is formed is insufficient, there is a problem that wrinkles and whitening occur in the resin sheet during metal vapor deposition processing. Furthermore, even if a resin that can solve the above problems is used, if the resin is expensive, there is a problem that the cost of the hologram forming sheet increases.

The present invention was devised in view of these circumstances, and uses polyethylene resin that has excellent transparency, suitability for metal vapor deposition, and gloss on the metal vapor deposited surface, and enables hologram formation to be performed at the same time as sheet forming. It is an object of the present invention to provide a method for manufacturing a hologram-formed sheet that has high efficiency, low energy loss, high suitability for machining of formed holograms, and can reduce manufacturing costs.

[Means to solve the problem]

The present invention is a polyethylene resin with a Vicat softening point of 90°C or higher that is melted and extruded from a T die into a thin film, or a T
A polyethylene resin with a Vicat softening point of 90°C or higher is melted from a die and extruded into a thin film on one side of the base sheet.
The structure was such that a hologram pattern was formed at the same time as the sheet was formed by pressing and cooling with a cooling roll having a hologram relief original on the circumferential surface.

[Effect]

The polyethylene resin melted and extruded into a thin film from the T-die is pressed and cooled by a cooling roll disposed on the hologram relief original plate or the peripheral surface, and a hologram pattern is integrally formed at the same time as sheet forming. Since the resin has a Vika-Soto softening point of 90°C or higher, the formed hologram pattern has excellent vapor deposition properties and is scratch-resistant.
Disappearance etc. will be less likely to occur.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of an extrusion laminator for explaining the present invention. In FIG. 1, an extrusion laminator 1 includes a T-die 2 for extruding molten polyethylene resin into a thin film, and a cooling roll 4 for pressing and cooling the molten polyethylene resin 3 extruded from the T-die 2 in the form of a thin film.
It also has a nip roll 5 and a winder 6 for winding up the formed hologram forming sheet 30.

The T-die 2 is not particularly limited, and a normal T-die for molding synthetic resin sheets can be used.

The polyethylene resin used in the present invention is a polyethylene resin having a Vicat softening point of 90° C. or higher.

The reason why the softening point of the polyethylene resin is limited to the Vicat softening point of 90°C or higher is to prevent the occurrence of scratches, disappearance of the hologram pattern, etc. due to various factors in the hologram pattern formed as described below. This is to improve vapor deposition suitability. Further, it is preferable that this polyethylene resin does not contain any additives that may be gasified in the metal reflective layer forming step described below.

Polyethylene resin 3 extruded into a thin film from T-die 2
The film thickness is preferably about 5 to 100 μm, especially about 15 to 3 μm.
Approximately 0 μm is preferable. If the film thickness is less than 5 μm, the sheet strength will be insufficient, and the adhesion to the base sheet (described later) will be insufficient. If the film thickness exceeds 30 μm, transparency will decrease, and if it exceeds 100 μm, the hologram will There is a problem that identifiability decreases.

As shown in FIG. 2, the cooling roll 4 is provided with a hologram relief original 7 on its peripheral surface.

As the hologram relief original plate 7 in the present invention, (
1) Chemical silver plating was applied to the secondary hologram surface on which relief-like interference fringes were recorded using photoresist as a light-sensitive material, and then nickel (N1) plating was applied on top of that, and then the Ni metal film was peeled off to form a leaf. Edition (press mask version), (
2) A relief plate formed by performing a peeling treatment on the relief surface of the press mask plate of (1) above, applying N1 plating again, and peeling off this Ni metal film, or (3) a thermoplastic resin sheet or film. A relief plate formed by hot pressing with the relief plate of (2) above can be used. Among these, the above (1) is selected from the viewpoint of durability of the relief plate during extrusion molding.

The Ni relief plate (2) is preferred.

The hologram relief original plate 7 may be placed on the circumferential surface of the cooling roll 4 by any method such as bonding with adhesive, fixing by vacuum adsorption, or mounting with bolts, as long as it does not fall off during extrusion molding. There are no particular restrictions. Also,
The number of hologram relief masters 7 arranged on the circumferential surface of the cooling roll 4, the arrangement pattern, the arrangement interval, etc. can be determined as appropriate depending on the intended hologram-forming sheet. By changing the hologram relief original plate 7 disposed on the circumferential surface of the cooling roll 4 to a hologram relief original plate of an appropriate capacity, the hologram pattern can be changed depending on the purpose of use, for example, in a polyethylene resin sheet of the same shape. I can do it.

The temperature of the cooling roll 4 can be determined from the film thickness, extrusion amount, etc. of the polyethylene resin 3 extruded from the T-die 2, and is usually preferably about 15 to 25°C.

The molten polyethylene resin 3 extruded into a thin film from the T-die 2 of the extrusion laminator 1 described above is pressed and cooled by a cooling roll 4 and a nip roll 5 to form a sheet 3.
At this time, a hologram pattern is integrally formed on the sheet 30 by the hologram relief original plate 7 disposed on the circumferential surface of the cooling roll 4. Figure 3 shows
FIG. 3 is a diagram showing a cross section of a hologram forming sheet 30 formed in this manner. In FIG. 3, the hologram forming sheet 30 has a hologram pattern integrally formed on one side thereof (the side that was in contact with the cooling roll 4).

Furthermore, as shown in FIG. 4, a metal reflective layer 8 may be provided on the hologram pattern forming surface of the hologram forming sheet 30 to form a hologram with metallic luster. The metal reflective layer 8 may be formed by depositing a metal such as aluminum, a metal oxide such as zinc oxide, or the like by vacuum evaporation, sputtering, ion blasting, or the like.

Incidentally, instead of the metal reflective layer as described above, a compound or resin, such as Zn, which has a difference in refractive index of light from the resin on which the hologram pattern is formed is preferably 0.5 or more, may be used.
By forming a thin film layer of a transparent compound such as S (zinc sulfide) or 5b2S3 (antimony trisulfide), it is possible to create a hologram-forming sheet that can reproduce a hologram image, although the sheet itself is transparent. .

FIG. 5 is a schematic diagram of an extrusion laminator for explaining another embodiment of the present invention. In FIG. 5, the extrusion laminator 20 is similar to the extrusion laminator 1 shown in FIG.
In addition, the unwinder 9 is configured to supply the base sheet lO between the cooling roll 4 and the nip roll 5.

For this reason, the molten polyethylene resin 3 extruded into a thin film 14 from the T-die 2 of the laminator 1 is laminated with the base sheet 10 and is pressed and cooled by the cooling roll 4 and nip roll 5 to form the sheet 30. At this time, a hologram pattern is integrally formed on the polyethylene resin layer 31 side by the hologram relief original plate 7 disposed on the circumferential surface of the cooling roll 4 (see FIG. 6). Note that the polyethylene resin layer 3 of the hologram forming sheet 30
A metal reflective layer 8 may be provided on the hologram pattern forming surface on the first side.

As the base sheet 10, stretched polypropylene film, polycarbonate film, polyester film,
Cellophane film or the like can be used. The thickness of the base sheet 10 is preferably about 10 to 200 μm.

Furthermore, an anchor agent, adhesive, or the like may be applied to the side of the base sheet 10 to be laminated with the molten polyethylene resin 3, if necessary.

Next, the present invention will be explained in more detail by showing experimental examples.

Experimental Example In an extrusion laminator 20 as shown in FIG. 5, extrusion lamination was performed using the following polyethylene resin and base sheet under the following extrusion conditions to produce a hologram forming sheet (Sample-1). In this case, after the relief surface of the press mask plate was subjected to a peeling treatment, N1 plating was applied again to the cooling roll, and a hologram relief plate formed by peeling off this Ni metal film was bonded to the cooling roll using an adhesive.

・Polyethylene resin Mitsui Petrochemical Industries M-16P MFR (processability) = 3.7 g/10m1n.

Vicat softening point = 95°C - Base sheet stretched polypropylene film (25 μm) - Extrusion conditions Screw L/D = 24 Cylinder temperature: 140°C, 180°C.

220℃ Adapter temperature = 280℃ T-die temperature = 290℃ Laminate thickness = 30μm Cooling roll temperature = 23℃ In addition, polyethylene resin C-25 manufactured by Mitsui Petrochemical Industries
A hologram-forming sheet was manufactured under the same conditions as described above, except that Sample No. 1-4 (MFR (processability) = 6.8, Vicat softening point = 105°C) was used (Sample-2).

Furthermore, we added polyethylene resin to Mitsui Petrochemical Industrial C-2.
A hologram-forming sheet was manufactured under the same conditions as Material-1 (Sample-3) except that the material was 60-4P (MFR (processability) = 2.8, Vicat softening point 109°C).

For comparison, polyethylene resin was manufactured by Mitsui Petrochemical Industries, Ltd.
-1OL (MFR (processability) = 8.0, Vicat softening point = 85°C), but a hologram-forming sheet was manufactured under the same conditions as above (comparative sample).

Sample-1, Sample-2, Sample-3, and Comparative Sample manufactured as described above were wound up, and then aluminum was vapor-deposited on the hologram forming surface using a vapor deposition machine. As a result, samples 1, 2, and 3 were free from thermal wrinkles, scratches, and the like, and hologram-forming sheets with excellent gloss on the metal-deposited surfaces were obtained.

On the other hand, in the comparative sample, thermal wrinkles, whitening of the aluminum-deposited surface, etc. occurred, and the surface properties of the metal-deposited surface significantly deteriorated, and a portion of the hologram disappeared due to thermal softening of the polyethylene resin layer.

In addition, samples-1゜-2, which were subjected to aluminum vapor deposition,
-3 and the comparative sample were each wound to a length of 2000 m, and stored in that state at a temperature of 30° C., and the appearance of the hologram pattern near the winding core was observed. The results are shown in the table below.

Change in hologram pattern over time As is clear from the above results, the higher the Vicat softening point of the polyethylene resin, the better the storage stability of the hologram pattern. Practically speaking, it is necessary to have a shelf life of about 4 weeks in a rolled state, and for this purpose, it is necessary to use a polyethylene resin with a Vicat softening point of 90° C. or higher.

〔Effect of the invention〕

According to the present invention, since a hologram pattern is integrally formed at the same time as polyethylene resin sheet molding, the work efficiency of hologram formation is high and energy loss is small, and the polyethylene resin has a Vicat softening point of 90°C.
is above, it is difficult for the formed hologram pattern to be damaged or disappear, and the evaporation suitability is good, and furthermore, an increase in manufacturing costs can be avoided. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an extrusion laminator for explaining the present invention, FIG. 2 is an explanatory diagram of hologram formation in the present invention, and FIGS. 3 and 4 are hologram-forming sheets manufactured according to the present invention. FIG. 5 is a schematic view of an extrusion laminator for explaining another embodiment of the present invention, and FIG. 6 is a cross-sectional view of a hologram forming sheet manufactured according to the present invention. 1.20...Extrusion laminator, 2...T die, 3
... Molten thin film polyethylene resin, 4... Cooling roll, 5... Nip roll, 6... Winder 7.
...Hologram relief plate, 8...Metal reflective layer, 9.
...Unwinder-10...Base material sheet, 30...
Hologram forming sheet, 31... polyethylene resin layer.

Claims (1)

[Claims] 1. Vicat polyethylene resin with a softening point of 90°C or higher that is melted from a T-die and extruded into a thin film, or Vicat that is melted from a T-die and extruded into a thin film on one side of a base sheet. A method for producing a hologram-formed sheet, characterized in that a hologram pattern is formed simultaneously with sheet molding by pressing and cooling a polyethylene resin having a softening point of 90° C. or more with a cooling roll having a hologram relief original on the peripheral surface. 2. The method for producing a hologram forming sheet according to claim 1, wherein a metal reflective layer is provided on the hologram pattern forming surface.