JP2582772B2 - Reversible image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a reversible image using a reversible recording material capable of reversibly forming and erasing an image.

2. Description of the Related Art At present, as a method of forming an image by pressure, a method of performing pressure printing on carbon paper or carbonless paper with a ballpoint pen or a method of performing pressure printing on paper through an ink ribbon such as that used in an impact printer. A method of transferring ink to paper has been widely adopted.

However, the conventional image forming method using pressure cannot be used repeatedly, and thus has a disadvantage that the cost increases.

An object of the present invention is to provide a method for forming a reversible image which is excellent in image contrast and resolution and can be used repeatedly without deteriorating image quality.

Structure The method for forming a reversible image of the present invention is characterized in that pressure printing is performed on a reversible recording material having a recording layer mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material. It is assumed that.

The recording principle of the present invention utilizes a reversible change in transparency depending on the pressure and temperature of the recording layer. That is, first, the recording layer is assumed to be, for example, cloudy and opaque. When the recording layer in such a cloudy state is pressurized, it becomes transparent, and when further heated, it becomes a translucent state intermediate between the maximum transparency and the maximum transparency. Next, when the temperature is decreased, the state returns to the original cloudy and opaque state. When pressure is applied again to this, it becomes transparent.
Therefore, for example, after heating the entire reversible recording material having such a recording layer, it is cooled to room temperature to make it cloudy and opaque, and a transparent image is formed by applying pressure to the image.

If a colored sheet is arranged on the back surface of a recording material having such a transparent image, this image can be recognized as an image of the color of the colored sheet against a white background.

The recording material having the transparent image can be used as it is as a cause for an overhead projector.

Above recording and erasing of the reversible recording material, such as it may be repeated at least 10 about ⁴ times.

The change in cloudiness-transparency of the recording layer in the present invention is considered to be due to the size or structure of the crystals in the organic low-molecular substance particles dispersed in the resin matrix. That is, at the time of cloudiness, each organic low-molecular substance particle is composed of polycrystals, which are aggregates of small crystal grains.Since light is scattered at the interface between the crystals, it appears macroscopically cloudy, while on the other hand, at the time of transparency, each particle Is a large single crystal having the same refractive index as the resin base material, and light is transmitted through the crystal without being scattered, so that it looks macroscopically transparent.
Further, it is considered that the above-described change of cloudiness to transparency follows the general principle of solid phase growth of crystals. In other words, the change from cloudy to transparent is achieved by consolidating the crystal grains in the direction of releasing the strain energy in the crystal grains and the energy of the grain boundaries by pressing the polycrystal, and as a result, the crystal grows gradually into a large single crystal On the other hand, the change from transparent to white turbidity means that a single crystal is heated and melted and rapidly cooled, whereby a large number of small crystal grains are precipitated and polycrystallized.

In order to prepare the reversible recording material used in the present invention, generally, (1) a solution in which two components of a resin base material and an organic low-molecular substance are dissolved, or a solution of a resin base material (the organic low-molecular substance is not dissolved as a solvent) Is applied (or impregnated) onto a support such as paper, a plastic film, a glass plate, or a metal plate.
Drying to form a recording layer, or (2) kneading the two components in the presence or absence of a solvent, if necessary, while heating, forming this into a sheet, and forming the recording sheet itself. It is made by doing. Examples of the solvent include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene and the like. It goes without saying that in the case of using a dispersion or a kneaded material, the organic low molecular weight substance is precipitated as fine particles and exists in a dispersed state, not to mention the case where a dispersion is used.

The resin base material used for the recording layer is a material that forms a layer in which organic low-molecular substances are uniformly dispersed and held, and that affects the transparency at the time of maximum transparency. For this reason, the base material is preferably a resin which has good transparency, is mechanically stable, and has good film-forming properties. Examples of such a resin include polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, and vinyl chloride-acrylate copolymer. Polyvinylidene chloride, such as polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer; polyester; polyamide; polyacrylate or polymethacrylate or acrylate; Examples include methacrylate copolymers and silicone resins. These may be used alone or as a mixture of two or more.

On the other hand, as the organic low-molecular substance, any substance that changes from polycrystal to single crystal depending on the pressure in the recording layer may be used, and one having a melting point of 30 to 200 ° C, preferably about 50 to 150 ° C is generally used. Such organic low molecular substances include alkanols; alkane diols; halogen alkanols or halogen alkane diols; alkylamines;
Alkene; alkyne; halogen alkene; halogen alkyne; halogen alkyne; cycloalkane; cycloalkene; cycloalkyne; saturated or unsaturated mono- or dicarboxylic acid or ester, amide or ammonium salt thereof; saturated or unsaturated halogen fatty acid or these. Ester, amide, or ammonium salt; allylcarboxylic acid or an ester, amide, or ammonium salt thereof; halogen allylcarboxylic acid or an ester, amide, or ammonium salt thereof; thioalcohol; thiocarboxylic acid or an ester, amine, or ammonium salt thereof A carboxylic acid ester of a thioalcohol; These may be used alone or in combination of two or more. These compounds have 10 to 10 carbon atoms.
30 is preferred. The alcohol group in the ester may be saturated or unsaturated, and may be halogen-substituted. Any case the oxygen in the organic low-molecular material is molecules also, nitrogen, sulfur and halogens at least one, for example -OH, -COOH, -CONH, -COOR, -NH, -NH 2, -
Compounds containing S-, -SS-, -O-, halogen, and the like are preferable.

More specifically, these compounds include lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid,
Stearic acid, behenic acid, nonadecanoic acid, arachiic acid,
Higher fatty acids such as oleic acid; esters of higher fatty acids such as methyl stearate, tetradecyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate, docosyl behenate; C ₁₆ H ₃₃ —O
−C ₁₆ H ₃₃ , C ₁₆ H ₃₃ −S−C ₁₆ H ₃₃ , C ₁₈ H ₃₇ −S−C ₁₈ H ₃₇ , C ₁₂
H ₂₅ -S-C ₁₂ H ₂₅ , C ₁₉ H ₃₉ -S-C ₁₉ H ₃₉ , C ₁₂ H ₂₅ -SS
−C ₁₂ H ₂₅ , And ether or thioether. Among them, in the present invention, higher fatty acids, particularly higher fatty acids having 16 or more carbon atoms such as palmitic acid, stearic acid, behenic acid, and lignoceric acid are preferable, and higher fatty acids having 16 to 24 carbon atoms are more preferable.

The ratio between the organic low-molecular substance and the resin base material in the recording layer is preferably about 2: 1 to 1:16 by weight, more preferably 1: 1 to 1: 5. If the ratio of the base material is less than this, it becomes difficult to form a film holding the organic low-molecular substance in the base material,
On the other hand, since the amount of the organic low-molecular-weight substance is too small, opacity becomes difficult.

Additives such as a surfactant and a high-boiling solvent can be added to the recording layer in order to facilitate formation of a large number of the above components and a transparent image. Specific examples of these additives are as follows.

Examples of high-boiling solvents: tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, butyl oleate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, diphthalic phthalate -N
-Octyl, di-2-ethylhexyl phthalate, diisononyl phthalate, dioctyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, dibutyl adipate, di-n-hexyl adipate, di-adipate-
2-ethylhexyl, alkyl 610 adipate, di-2-ethylhexyl azelate, dibutyl sebacate,
Di-2-ethylhexyl sebacate, diethylene glycol dibenzoate, triethylene glycol di-2-ethyl butyrate, methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate.

Examples of surfactants and their many additives; polyhydric alcohol higher fatty acid esters; polyhydric alcohol higher alkyl ethers; polyhydric alcohol higher fatty acid esters, higher alcohols, higher alkyl phenols, higher fatty acid higher alkyl amines, higher fatty acid amides, fats and oils Or lower olefin oxide adduct of polypropylene glycol; acetylene glycol; Na, Ca, Ba or Mg salt of higher alkylbenzene sulfonic acid; higher fatty acid, aromatic carboxylic acid, higher aliphatic sulfonic acid, aromatic sulfonic acid, monosulfonic acid sulfate or Phosphoric acid mono- or di-ester Ca, Ba, or Mg; low sulfated oil; poly long chain alkyl acrylate; acrylic oligomer; poly long chain alkyl methacrylate; long chain alkyl methacrylate-amine-containing monomer copolymer; Styrene to anhydrous male Inic acid copolymer; olefin-maleic anhydride copolymer.

Hereinafter, the present invention will be described in more detail with reference to Examples.
All parts are parts by weight.

Example 1 A solution composed of 10 parts of behenic acid, 25 parts of vinyl chloride-vinyl acetate copolymer (VYHH manufactured by UCC) and 200 parts of tetrahydrofuran was coated on a 75 μm-thick polyester film with a wire bar, dried, and dried to 15 μm.
By providing a thick recording layer, a white opaque reversible recording material was prepared.

Next, when this reversible recording material was applied with a dot impact printer (SP250-15 manufactured by Ricoh, but without a ribbon), a clear transparent image was formed. This again
After heating to 80 ° C. and cooling, the image disappeared and the entire body turned white. Even when this operation was repeated 100 times, image formation and erasing were possible similarly.

Example 2 A white opaque reversible recording material was prepared in the same manner as in Example 1 except that 5 parts of di-2-ethylhexyl adipate was added to the solution.

Next, when an image was formed on this reversible recording material in the same manner as in Example 1, a clear image was obtained. This again
After heating to 80 ° C. and cooling, the image disappeared and the whole became white. Even when this operation was repeated 100 times, image formation and erasing were possible similarly.

Example 3 A white opaque reversible recording material was prepared in the same manner as in Example 2 except that 1 part of glyceryl monostearate was added to the solution.

Next, when an image was formed using this reversible recording material in the same manner as in Example 1, a clear image was obtained. After heating to 80 ° C. again and cooling, the image disappeared and the whole became white. Even when this operation was repeated 100 times, image formation and erasing were possible similarly.

Effect As described above, the method of the present invention utilizes the physical phenomenon of a change in the size of crystals, so that it has excellent advantages such as excellent image contrast and resolution, and can be used repeatedly without deteriorating the image quality. .

Claims (1)

(57) [Claims] 1. A reversible image printing method comprising: printing on a reversible recording material having a recording layer containing a resin base material and an organic low-molecular substance dispersed in the resin base material as main components. Forming method.