JPH0971047A - Thermal expansion sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal expansion sheet with which a stereoimage of a complicated pattern or a pattern having a large area can be obtained without turbulence and generation of unnecessary irregularities by using a stereoimage forming method. SOLUTION: In a thermal expansion sheet, a heat conductive layer 13 is formed on a base material 11 and a thermal expansion layer 15 is formed on the heat conductive layer 13. When an image 24 having light absorbency formed on the thermal expansion layer 15 is irradiated with light by a lamp 33, the light is absorbed by the image 24, so that it changes to heat energy. Accordingly, the thermal expansion layer 15 at the lower part of the image 24 is heated, so that the surface of the thermal expansion layer 15 is raised. Though the heat tends to concentrate to the central part of the image 24 at the time of heating of the thermal expansion layer 15 at this time, the heat becomes to be easily dispersed also to the lower part of the image 24 due to the heat conductive layer 13, so that uneven rise due to confined heat is eliminated.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermal expansion sheet for forming a three-dimensional image.

[0002]

2. Description of the Related Art Conventionally, a method of manufacturing a three-dimensional image forming sheet has been proposed. For example, in the method described in Japanese Examined Patent Publication No. 59-35359, a desired image is formed on the surface of a heat-expandable sheet with a material having higher light absorption than the sheet, and then the surface of the sheet is irradiated with light to absorb light. The image area is selectively heated and raised by the difference between the two.

Further, according to the image forming method described in Japanese Patent Laid-Open No. 61-72589, an image having high light absorption is formed by a thermal transfer method, and the image is irradiated with light for expansion recording material. An uneven pattern corresponding to the image signal is formed on the top.

According to these methods, the concavo-convex pattern can be formed on the sheet by a simple operation.

[0005]

However, when an image of a complicated pattern or an image of a large area is formed, an excessive heating portion is generated and uneven expansion occurs. There are problems that the pattern is disturbed and unnecessary unevenness occurs.

The present invention has been made in order to solve the above-mentioned problems, and a stereoscopic image of a complicated pattern or a pattern having a large area is disturbed or unnecessary by using the same stereoscopic image forming method as the conventional one. It is an object of the present invention to provide a heat-expandable sheet that can be obtained without causing unevenness.

[0007]

In order to achieve this object, the heat-expandable sheet of the present invention has a heat-conducting layer formed on a substrate and a heat-expanding layer formed on the heat-conducting layer. There is.

Therefore, in the heat-expandable sheet, first, a desired image is formed on the heat-expandable layer with a material having a high light absorption property. Next, the surface of the heat-expandable sheet is irradiated with light, and the light absorbing material absorbs light to generate heat. The thermal expansion layer heated by the heat generation of the light absorbing material expands to form a stereoscopic image.

At this time, the heating state tends to be different between the contour portion and the central portion of the image made of the light absorbing material. That is,
The heating in the central part of the image tends to be excessive compared to the heating in the contour part of the image. However, due to the heat conducting layer existing between the thermal expansion layer and the substrate, the excessive heating is diffused and the central portion and the contour portion of the image are in the same heating state, and a uniform expanded and raised stereoscopic image is formed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

A cross-sectional view of the heat-expandable sheet of this embodiment is shown in FIG. The heat-expandable sheet is a heat conductive layer 1 on the base material 11.
3 is formed, and the thermal expansion layer 15 is formed on the heat conduction layer 13.

The heat conductive layer is made of a material having a high heat conductivity.

A material having a high thermal conductivity has a thermal conductivity of 5 W.
/ M · K or more is preferable. For example, silver (410W
/ M ・ K), copper (385W / m ・ K), gold (290W /
m ・ K), aluminum (202W / m ・ K), iron (7
3W / mK, etc., or quartz (41.6W / mK)
There are non-metals such as K).

The heat conduction layer 13 is formed by depositing these substances on the substrate 11.

The thermal expansion layer 15 comprises a foaming agent 17 dispersed in a thermoplastic resin.

The foaming agent 17 includes bicarbonates such as sodium hydrogen carbonate, various peroxides, diazoaminobenzene,
Palladium aluminum borate, and azo compounds such as azobisisobutyronitrile that generate a nontoxic gas by thermal decomposition are preferably used.

Further, a shell material made of polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylic acid ester, polyacrylonitrile, polybutadiene, or a copolymer thereof is used in the interior of a shell material containing propane, butane, pentane or the like. Encapsulating a vaporizable substance with a boiling point,
A thermally expandable microcapsule having a diameter of 10 to 20 μm may be used as the foaming agent 17.

These foaming agents 17 are dispersed in a solution or emulsion of a resin used as a binder by using a known dispersing device such as a roll mill or a sand mill.
This dispersion is applied to the heat conductive layer 13 using a known coating device.
The thermal expansion layer 15 is formed by being applied on top and further dried.

The resin for the binder is a foaming agent 17
Is heated to cause thermal decomposition, and when a gas is generated, or when the heat-expandable capsule is thermally expanded, at the same time, heat-softens to form a stable heat-expandable layer 15,
Thermoplastic resins such as vinyl acetate polymers and acrylic polymers are preferably used.

The heat-expandable sheet may be produced by the above-described manufacturing method, or the same material may be used to bond the heat-conducting layer 13 sheet and the heat-expanding layer 15 sheet to each other on the base material 11. Morphology can be formed. It can be handled in exactly the same way as the heat-expandable sheet described above.

Next, a method for producing a stereoscopic image using the heat-expandable sheet having the above-described structure will be described with reference to FIGS.

First, as shown in FIG. 2, for example, a thermal transfer ribbon 22 which is generally used in a thermal transfer recording apparatus is superposed on the thermal expansion layer 15 of the thermal expansion sheet, and the back surface of the thermal transfer ribbon 22. Then, the thermal head 21 provided in the thermal transfer recording apparatus is pressed. Thermal head 2
When No. 1 is heated by being controlled by a control circuit (not shown) based on the image signal, the ink layer at the corresponding position on the thermal transfer ribbon 22 is melted and fused to the surface of the thermal expansion layer 15.
Then, if the thermal transfer ribbon 22 is peeled off after the ink has cooled, only the image portion of the ink layer of the thermal transfer ribbon 22 is transferred to the thermal expansion layer 15, and a figure, a character or the like is transferred onto the thermal expansion layer 15. An image 24 is formed.

In the present embodiment, the thermal head 21 of the thermal transfer recording apparatus was used to form the image 24 on the thermal expansion layer 15, but other types may be used. For example, the back surface of the thermal transfer ribbon 22 is scanned with a laser beam whose intensity is modulated based on an image signal to be heated, and the ink layer at a portion corresponding to the thermal transfer ribbon 22 irradiated with the intense laser beam is melted and heated. It may be fused to the surface of the expansion layer 15. Further, the ink on the ink ribbon may be transferred onto the thermal expansion layer 15 by the impact head.

Here, a material that absorbs light and generates heat is used for the ink such as the thermal transfer ribbon 22. For example, when it is desired to obtain a black image, carbon black may be used. Carbon black has the property of absorbing light from visible light to near infrared and converting its light energy into heat.

On the other hand, when an image other than black is required,
For example, known dyes and pigments such as red, blue, and yellow are used in the ink. However, since these dyes and pigments have little light absorption in the infrared region, sufficient light energy cannot be converted into heat. Therefore, it is necessary to increase the light absorption in the infrared region by appropriately mixing a composite oxide whose main component is an oxide of tin, antimony, or indium with the ink composition.

Next, the light irradiation will be described. As shown in FIG. 3, the lamp 33 is used to irradiate the thermally expansive sheet on which the image 24 having the light absorbing property is formed. As the lamp 33, a tungsten lamp, a halogen lamp, a xenon lamp, or the like that can emit light in the visible to infrared region is used.

When the light-absorbing image 24 formed on the thermal expansion layer 15 is irradiated with light by the lamp 33, the light is absorbed by the image 24 and converted into heat energy. Therefore, the thermal expansion layer 15 below the image 24 is heated. When the foaming agent 17 is used for the thermal expansion layer 15, the surface of the thermal expansion layer 15 rises due to foaming due to thermal decomposition of the foaming agent 17. When a thermally expandable capsule is used as the thermally expandable layer 15, the expansion of the capsule causes the surface of the thermally expandable layer 15 to rise, which results in the image 24.
A stereoscopic image sheet having a stereoscopic image formed on a portion corresponding to is formed.

At this time, when the lamp 33 irradiates light and the fan 34 blows air near the surface of the thermal expansion layer 15, it is possible to prevent the ambient temperature near the thermal expansion layer 15 from rising. As a result, the temperature difference between the portion that absorbs light and rises in temperature and the portion that reflects light and does not rise in temperature can be increased, and therefore only the portion of the thermally expansive layer 15 that is desired to be raised can be raised. Therefore, the resolution of the stereoscopic image can be improved.

By this light irradiation, the temperature of the image 24 having a light absorbing property formed on the thermal expansion layer 15 becomes 100 ° C. or higher. At this time, the thermal expansion layer 15 is heated,
The heat tends to concentrate in the central portion of the image 24. But,
The heat-conducting layer 13 also facilitates diffusion below the image 24, eliminating uneven ridges due to heat retention. Further, the image 24 can be three-dimensionalized without expansion in the direction of the heat conduction layer 13. Further, heat is not transmitted to the base material 11 and the base material 11 is not deformed.

By carrying out the above steps, heat can be generated only in the portion where the ink is transferred, and the surface of the heat-expandable sheet can be raised.

In FIG. 4, the image 24 having a large area is raised, but in this case as well, the heat conductive layer 13 uniformly transmits heat to the entire thermal expansion layer 15 corresponding to the image 24. The entire 24 can be raised uniformly.

The present invention is not limited to the above embodiments, but can be implemented in various forms within the scope of the invention.

For example, an overcoat layer may be formed on the heat expansion layer of the heat expansion sheet, or an adhesive layer may be formed on the back surface of the base material.

[0034]

As is apparent from the above description, when the thermal expansion sheet of the present invention is used, a stereoscopic image of a complicated pattern or a pattern having a large area is disturbed by using the same stereoscopic image forming method as the conventional one. It can be obtained without causing unnecessary unevenness. Furthermore, the resolution of the stereoscopic image can be increased. Further, there is no need to limit the type of base material of the thermal expansion sheet.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heat-expandable sheet according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a step of thermally transferring a light-absorbent image onto the heat-expandable sheet.

FIG. 3 is an explanatory diagram showing a process of three-dimensionalizing an image formed on the heat-expandable sheet.

FIG. 4 is an explanatory diagram showing a state in which a three-dimensional image having a large area is formed on the thermal expansion sheet.

[Explanation of symbols]

 11 Base Material 13 Thermal Conduction Layer 15 Thermal Expansion Layer 17 Foaming Agent

Claims (1)

[Claims] 1. A heat-expandable sheet comprising a heat-conductive layer formed on a base material and a heat-expandable layer formed on the heat-conductive layer.