JPS588983B2 - Retroreflective sheet with contrasting color embossing ability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a retroreflective sheet having a novel ability to emboss contrasting colors, and its purpose is to eliminate the complicated processes found in conventional general retroreflective sheets. A reflective material that is extremely useful in practice as an information medium that makes it possible to record and display any information semi-permanently with extremely simple operations such as embossing at normal room temperature without the need for It is located in a place that provides.

Conventional retroreflective sheet (hereinafter simply referred to as reflective sheet).

) has the property of efficiently retro-reflecting light towards the incident light source, so it is widely used as traffic signs, information signs, car license plates, stickers, advertising media, and other insignia, mainly to improve visibility at night. It is used.

By the way, as a method for writing specific information such as letters, numbers, and patterns on or inside these reflective sheets, it is best to use ordinary transparent or opaque ink and apply ordinary screen printing, offset printing, gravure printing, etc. Common.

However, although these methods are advantageous for writing the same information on multiple sheets or multiple times, they generally result in large economic and time losses as a method for recording and displaying information consisting of various miscellaneous requests. It's grossly inefficient.

In view of the above-mentioned problems, the present inventors have developed a method for recording and displaying arbitrary information on a reflective sheet simply, reliably, and inexpensively without impairing the original optical function or physical properties of the reflective sheet. As a result of intensive research into the method, the present invention was arrived at.

The reflective sheet with contrasting color embossment ability of the present invention maintains the characteristics of a conventional reflective sheet, and can be easily operated by embossing various information made up of various miscellaneous requirements at normal room temperature. This makes it possible to record and display instantaneously with just a hand.

That is, the reflective sheet composition according to the present invention can be used to form alphabetic characters, iroha characters such as hiragana or katakana,
If you have an embossing machine consisting of a male mold and a female mold that cover numbers, symbols, and other patterns, by embossing the sheet between the two molds, the embossed part will change to a white color that contrasts with the background color. Since then, it has become possible to instantly record and display any information.

To explain the invention in detail, the present invention provides a flexible structure consisting of a large number of tiny high refractive index glass beads encapsulated in a transparent colored binder resin and a light reflective layer behind them while maintaining a constant optical relationship. Non-plastic polyvinyl chloride, a vinyl copolymer mainly composed of vinyl chloride, or other cold-flowing material at room temperature is applied to the surface layer of the retroreflective sheet with a transparent adhesive as necessary. When given a transformation,
The object of the present invention is to provide a retroreflective sheet having contrasting color embossment ability, which is characterized by being provided with a transparent resin layer mainly containing a component that causes a remarkable devitrification whitening phenomenon.

The composition of the present invention will be explained with reference to the drawings. Fig. 1 is a cross-sectional view thereof, in which 1 is a transparent resin layer which causes a remarkable devitrification whitening phenomenon when subjected to cold flow deformation at room temperature; 2 3 is a transparent adhesive layer provided as necessary, 3 is a transparent colored binder resin layer of the reflective sheet, 4 is a layer of minute high-refractive index glass beads, 5 is a light reflective layer, and 6 is a desired adhesion layer. The adhesive layer 7 for attachment to the body is a flexible release film.

Figure 2 is a cross-sectional view of the raised part after embossing.Generally, as shown in the figure, embossing is performed with the adhesive and release film still attached to the intended adherend, and then the mold is released. It is convenient to peel off only the film and apply it.

An example of a transparent resin used for the surface layer in the present invention that causes a remarkable devitrification whitening phenomenon when subjected to cold flow deformation at room temperature is the hard non-plastic polychloride resin proposed in Japanese Patent Publication No. 37-9335. Vinyl and vinyl chloride/vinyl acetate copolymers are suitable, and acetylcellulose and vinyl chloride/(meth)acrylic acid ester copolymers are also effective.

These resins are further mixed with relatively small amounts of stabilizers, lubricant reinforcing fillers, etc., and are used as thin film plates having a thickness of 50 to 1000 microns, preferably 100 to 500 microns.

When a thin plate made of these compounds is subjected to cold flow deformation exceeding the critical yield point by stretching or bending at room temperature, local physical and optical distortion occurs, resulting in significant devitrification and whitening.

Although the mechanism by which this phenomenon occurs has not yet been completely elucidated, it is predicted that oriented crystallization during cold stretching of the polymer chain from an amorphous state is involved.

Next, as the reflective sheet used for the lower layer, any reflective sheet manufactured by a conventionally known method can be used as long as it is of the glass bead-filled type, but the sharpness and beauty of the embossed part after embossing are important. When this is required, it is desirable to have as much flexibility as possible without cracking during embossing.

For example, a transparent colored binder resin made of flexible acrylic resin or urethane resin and having a thickness of about 50 to 200 microns is suitable.

Here, if the flexibility of the reflective sheet is expressed as the elongation at break in a tensile test under normal deformation rate conditions (10-1 to 10-2 sec-1) at room temperature, the elongation at break is 50 % or more is desirable.

The main components of the present invention are as described above, but in order to attach the sheet to the intended adherend, a pressure-sensitive or heat-sensitive adhesive is applied to the back surface in advance, and then released. Although the mold material may be, for example, highly flexible paper, it is practically advantageous to handle the mold material while protecting it with a flexible mold release film such as polyethylene or polypropylene.

As described in detail above, the present invention provides a conventional reflective sheet with embossed letters, numbers, symbols, and other arbitrary characters in opaque white color that contrasts with the reflective background color of red, blue, green, etc. by a simple embossing operation. It was a success in recording and displaying information, and from a different perspective, it was a success in efficiently converting a conventional simple contrasting color embossed display sheet into a reflective one.

With this reflective sheet, the embossed areas become devitrified and white, while the non-embossed areas maintain their colored reflective background, which improves visibility at night, which was not possible with conventional simple contrasting color embossed display sheets. This greatly contributes to the improvement of distinguishability, and its uses will be greatly expanded.

To give a specific example, by processing the sheet into a tape shape, using a ready-made simple embossing device, you can write any name, year, month, year, number, time, weight, distance, operating method, and other precautions. Displays, etc. can be immediately stamped out and affixed to the intended adherend.

They shine brightly when illuminated by an external light source in darkness such as at night or during a power outage, and are effective in improving readability when the information displayed on the sheet is within a legible distance. By using a sheet with an appropriately changed reflective color, it is useful for identifying and confirming the adherend even from a distance where it cannot be read, and it is also effective in preventing traffic accidents caused by car collisions when outdoors. The present invention will be explained in detail by showing specific examples below.

Example 1 The following composition was used as a transparent film-like thin plate that causes a devitrification whitening phenomenon when subjected to cold flow deformation at room temperature, and was mixed in a semi-molten state on a kneading roll heated to about 150°C. A thin film-like plate having a thickness of about 180 μm was formed between calender rolls heated to about 145° C. to 155° C., and after cooling, it was wound up.

Vinyl chloride/vinyl acetate 100 parts (87/1
3) Copolymer organotin maleate 2 parts Cadmium stearate 0.5 parts Transparent lubricant
0.2 part Next, using a flexible polyurethane mixed with a green transparent pigment as a glass bead binder resin, which was manufactured in a separate process, an acrylic pressure-sensitive adhesive was applied to the back of the aluminum vapor deposited layer, which is a light reflective layer. After applying a transparent urethane adhesive to a thickness of about 5μ on the surface of a reflective sheet with a total thickness of about 180μ on which a polyethylene release film with a thickness of 50μ was provided, the vinyl chloride/vinyl acetate copolymer transparent was applied. The thin plates were laminated and bonded.

When the thus produced sheet was slit into a 12 mm wide tape and letters were embossed using a hand embossing device, bright white letters were embossed on the green reflective background.

On the other hand, as a comparative example, the same characters are embossed on a currently commercially available green non-reflective embossed tape and a tape made of a normal retroreflective sheet before the vinyl chloride/vinyl acetate copolymer transparent thin plate described above is laminated and bonded. These three items were attached to the sides of separate suitcases.

At night, when these suitcases were placed 5Qm away and the headlights of a car were turned down, the presence of conventional non-reflective embossed tape was not recognized at all, and the entire surface of regular retroreflective tape was green. In contrast, with the reflective embossed tape of this example, only the other parts of the reflective embossed tape glowed brightly in green, making the embossed characters stand out and clearly visible. Ta.

As described in detail in the examples above, the most important feature of the present invention is that it gives a conventional reflective sheet a new function as an information medium, and it is expected to open up new fields of use for reflective sheets. Ru.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a retroreflective sheet having a contrasting color embossing ability according to the present invention, and FIG. 2 is a schematic cross-sectional view of the sheet after embossing. 1 is a transparent resin layer, 2 is a transparent adhesive, 3 is a transparent binder resin layer, 4 is a glass bead layer, 5 is a light reflecting layer, 6 is an adhesive, and 7 is a release film.

Claims (1)

[Claims] 1. A flexible device consisting of a large number of minute high-refractive index glass beads encapsulated in a transparent colored binder resin and a light-reflecting layer behind them while maintaining a certain optical relationship. On the surface layer of the retroreflective sheet, non-plastic polyvinyl chloride, a vinyl copolymer mainly composed of vinyl chloride, or other material that has been subjected to cold flow deformation at room temperature is applied via a transparent adhesive as necessary. 1. A retroreflective sheet having a contrasting color embossment ability, characterized in that it is provided with a transparent resin layer mainly containing a component that causes remarkable devitrification and whitening phenomenon when exposed to water. 2. Retroreflection having contrasting color embossment ability as set forth in claim 1, wherein a pressure-sensitive adhesive or a heat-sensitive adhesive is applied to the back side of the sheet, and the surface is protected with a flexible release material. sheet.