JP2884931B2 - Rewritable thermal recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rewritable thermosensitive recording medium having a recording layer whose transparency reversibly changes depending on temperature, and in particular, dramatically expands its transparency temperature range. The present invention relates to a thermosensitive recording medium which can be made and in which the contrast between an image portion and a non-image portion is hardly reduced.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 55-154198 and U.S. Pat.
As described in JP-A No. 3 (1993) -1991, a recording layer mainly composed of a thermoplastic resin such as polyvinyl chloride and a low-molecular organic substance such as a higher fatty acid dispersed in the resin is provided on a support. A structure having such a structure is known.

[0003] In this thermosensitive recording medium, the optical absorption characteristic (light scattering characteristic) of the recording layer is skillfully utilized by reversibly changing depending on temperature. In other words, the recording layer has a specific temperature T near room temperature.
_It has two state transition temperatures T ₁ and T ₂ (where T ₁ <T ₂ ) at a temperature higher than _{0. When} the recording layer is heated above T ₂ and held and then cooled below T ₀ , it becomes cloudy. Meanwhile the light scattering becomes maximum shielding state increases, the cooling of the recording layer in this opaque state above T ₁ is heated to less than T ₂ and after holding the T ₀ following the light scattering property decreases It becomes a transparent state. In addition, the maximum light-shielding state and the transparent state of the recording layer can be stably maintained under the temperature condition of T ₀ or less, and these states can be reversibly changed. By setting to, the recording medium can be differentiated from the other state and can be used as a rewritable recording medium.

Since the recording layer can be made transparent in a temperature range from T ₁ to T ₂ , this temperature range is called a transparency temperature range.

Meanwhile, in this type of thermosensitive recording medium in the prior above clearing temperature range is very narrow as about 2 to 4 ° C., thus, a part or whole of the recording layer in the opaque state above T ₁ T ₂ However, there is a problem that the temperature control becomes extremely difficult when the transparent material is heated to a temperature lower than the above.

Therefore, Japanese Patent Application Laid-Open No. 2-1363 discloses that at least one kind of higher fatty acids having 16 or more carbon atoms and at least one of aliphatic saturated dicarboxylic acids and derivatives thereof are used for the organic low-molecular substance dispersed in the resin matrix. By applying a kind of the above-mentioned organic low-molecular substance, Japanese Unexamined Patent Publication No. Hei.
Means for expanding the above-mentioned clearing temperature range by applying at least one kind of higher fatty acid of 6 or more and at least one kind of aliphatic saturated dicarboxylic acid having 20 or more carbon atoms have been proposed.

[0007]

By applying these means, it is certainly possible to slightly increase the above-mentioned transparentizing temperature range.

However, as will be apparent from the comparative examples described later, the transparency temperature range expanded by these means is still as narrow as about 20 ° C., which is not a means for completely solving the above problem. In addition, this causes the following problems. That is, in this type of thermal recording medium, it is theoretically possible to form a transparent image based on a white background (that is, a cloudy state) by using a heating means such as a thermal head. Since the temperature range is still narrow and it is practically difficult to set the heating temperature of the thermal head or the like at a high speed within the above-mentioned temperature range, heat is usually transferred between the heating rollers set at an appropriate temperature within the above-mentioned transparency temperature range. after uniformly is transparent and the recording layer by inserting a recording medium, turbidity T ₂ or more heated using a thermal head or the like heating means selectively cloudiness is caused by transparent areas (i.e. transparent state) based A method of forming an image in a state is adopted.

Therefore, a recorded image formed by such a method is a black-and-white inverted image (a so-called negative pattern) as compared with a normal image original composed of a black image on a white base. There has been a fatal problem that the application range of various types of thermal recording media is limited to special fields.

In the case where the range of the clearing temperature is to be increased by each means disclosed in the above-mentioned publications, the mixing ratio of the aliphatic saturated dicarboxylic acid to the higher fatty acid is clearly understood from the results of the examples described in each publication. Is low, the expanded temperature range is small.

On the other hand, when the proportion of the aliphatic saturated dicarboxylic acid with respect to the higher fatty acid is increased, the clearing temperature range is widened. On the other hand, when the proportion of the higher fatty acid is decreased with the increase of the aliphatic saturated dicarboxylic acid, the recording layer is not regenerated. The degree of cloudiness also tends to decrease (see Table 2 of JP-A-3-2089), and the problem that the contrast between the cloudy portion and the transparent portion (corresponding to the image portion and the non-image portion) cannot be sufficiently obtained. There was a point.

Under such technical background, the present inventors have already proposed a heat-sensitive recording medium which can drastically expand the above-mentioned transparency temperature range and in which the contrast between an image portion and a non-image portion is hardly reduced. (See Japanese Patent Application No. 3-304690).

The present invention relates to an improvement of the invention described in the specification of Japanese Patent Application No. 3-304690, and it is an object of the present invention to further expand the transparentizing temperature range.
An object of the present invention is to provide a thermosensitive recording medium capable of expanding a transparent temperature range even when a thermosetting resin is applied as a resin base material in order to improve repetitive rewriting resistance.

[0014]

That is, the invention according to claim 1 comprises a resin base material and an organic low-molecular substance dispersed in the resin base material, and its transparency is reversible depending on temperature. Assuming a rewritable heat-sensitive recording medium having a recording layer that changes to the same type, in the organic low-molecular substance dispersed in the resin base material, the same kind of cis-type and trans-type alicyclic type
Composed of dicarboxylic acid compound and cis type: trans
The mixing ratio of the mold is within the range of 8: 2 to 2: 8 by weight.
It is characterized in that the set mixture is added.

In such technical means, as a resin base material constituting a part of the recording layer, an organic low-molecular substance described below, a cis-type or a trans-type alicyclic dicarboxylic acid compound, and a refractive index thereof are used. Thermoplastic resins which are similar and have no compatibility, have excellent mechanical strength, and have good film-forming ability and good transparency are mentioned. Specific examples thereof include polyester resins such as saturated copolymerized polyesters; polyvinyl chloride resins; Vinyl chloride copolymers such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer; polychlorinated Vinylidene chloride; vinylidene chloride such as vinylidene chloride-vinyl chloride copolymer and vinylidene chloride-acrylonitrile copolymer Polymer; polyamide resin; silicone resin; There are polyacrylate or polymethacrylate resin, or this copolymer and the like, etc. can be applied as a mixture which like alone, or two or more kinds.

Further, it is composed of a hydroxyl-modified vinyl chloride-vinyl acetate copolymer and an isocyanate compound, and has a refractive index similar to that of the above-mentioned organic low molecular weight substance and alicyclic dicarboxylic acid compound and is incompatible with them. A thermosetting resin having good properties can also be applied.

Here, the hydroxyl-modified vinyl chloride-
The vinyl acetate copolymer means a vinyl chloride-vinyl acetate copolymer into which a hydroxyl group (-OH) is introduced in an amount of about 0.5 to 10% by weight. For example, a vinyl chloride-vinyl acetate-vinyl alcohol copolymer is used. Polymer or vinyl chloride
Examples thereof include an alkyl acrylate copolymer having a vinyl chloride-vinyl acetate-hydroxyl group, such as a vinyl acetate-hydroxyalkyl acrylate copolymer. On the other hand,
The isocyanate compound constituting the thermosetting resin as the resin base material by reacting with the hydroxyl group of the hydroxyl-modified vinyl chloride-vinyl acetate copolymer generally has an isocyanate group (-N = C = O). An isocyanate compound widely used as a cross-linking agent can be applied. For example, toluylene diisocyanate, dimer of 2,4 toluylene diisocyanate, naphthylene-1,5-diisocyanate, o-toluylene diisocyanate , Diphenylmethane diisocyanate, triphenylmethane triisocyanate, tris- (p-isocyanatophenyl) thiophosphite, polymethylene polyphenyl isocyanate, polyfunctional aromatic isocyanate, aromatic polyisocyanate, polyfunctional aliphatic Isocyanate, hexamethylene diisocyanate Diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and the like.

Next, the organic low-molecular substance dispersed in the resin matrix contains at least one atom of oxygen, sulfur, nitrogen, and halogen, has 10 to 40 carbon atoms, and has a molecular weight of 100 to 100. 700 and the melting point is 50-
Organic compounds in the range of 150 ° C. are mentioned, and specific examples thereof include higher alcohols such as alkanols, alkanediols, halogen alkanols, and halogen alkane diols; higher aliphatic amines; alkanes, alkenes, alkynes and halogen-substituted products thereof. Cyclic compounds such as cycloalkanes, cycloalkenes and cycloalkynes; saturated carboxylic acids, unsaturated monocarboxylic acids, dicarboxylic acids or esters, amides and ammonium salts thereof; saturated or unsaturated halogen fatty acids or esters and amides thereof Acrylic acid or their esters, amides, ammonium salts; halogen allyl carboxylic acids or their esters, amides, ammonium salts; thioalcohols or their carboxylic acid esters;
There are thiocarboxylic acids or their esters, amides, ammonium salts and the like, and these can be used alone or in combination of two or more.

On the other hand, the cis-type and trans-type alicyclic dicarboxylic acid compounds added to the organic low-molecular substance dispersed in the resin base material are compatible with the organic low-molecular substance and have a compatibility with the resin base material. Is a compound having no compatibility, for example,
1,2-ciscyclopropanedicarboxylic acid (mp139
C), cyclopropanedicarboxylic acids such as 1,2-transcyclopropanedicarboxylic acid (mp 175C);
1,2-ciscyclobutanedicarboxylic acid (mp138
C), 1,2-transcyclobutanedicarboxylic acid (m
p137 ° C), cyclobutanedicarboxylic acids such as 1,3-ciscyclobutanedicarboxylic acid (mp143 ° C), 1,3-transcyclobutanedicarboxylic acid (mp171 ° C); 1,2-ciscyclopentanedicarboxylic acid (mp
Cyclopentanedicarboxylic acid such as 1,2-transcyclopentanedicarboxylic acid (mp181 ° C), 1,3-ciscyclopentanedicarboxylic acid (mp121 ° C), 1,3-transcyclopentanedicarboxylic acid (mp188 ° C) Acids: 1,2-ciscyclohexanedicarboxylic acid (mp 170 ° C.), 1,2-transcyclohexanedicarboxylic acid (mp 310 ° C.), 1,3-ciscyclohexanedicarboxylic acid (mp 187 ° C.), 1,3-
Transcyclohexanedicarboxylic acid (mp148
C), 1,4-ciscyclohexanedicarboxylic acid (mp
192 ° C.) and cyclohexanedicarboxylic acids such as 1,4-transcyclohexanedicarboxylic acid (mp 221 ° C.).

The invention according to claim 2 provides a cis-type alicyclic dicarboxylic acid compound selected from the group consisting of these materials,
A mixture comprising a trans-type alicyclic dicarboxylic acid compound of the same type as the s -type alicyclic dicarboxylic acid compound is applied.

That is, the invention according to claim 2 is based on claim 1.
Assuming that the heat-sensitive recording medium according to
-Ciscyclopropanedicarboxylic acid, 1,2-ciscyclobutanedicarboxylic acid, 1,2-ciscyclopentanedicarboxylic acid, 1,2-ciscyclohexanedicarboxylic acid, 1,3-ciscyclobutanedicarboxylic acid, 1,3-
Ciscyclopentanedicarboxylic acid, 1,3-ciscyclohexanedicarboxylic acid, and a cis-type alicyclic dicarboxylic acid compound selected from 1,4-ciscyclohexanedicarboxylic acid, and 1,2-transcyclopropanedicarboxylic acid, 1,2-transcyclobutanedicarboxylic acid, 1,2-transcyclopentanedicarboxylic acid,
1,2-transcyclohexanedicarboxylic acid, 1,3
A trans-cycloaliphatic dicarboxylic acid compound selected from transcyclobutanedicarboxylic acid, 1,3-transcyclopentanedicarboxylic acid, 1,3-transcyclohexanedicarboxylic acid, and 1,4-transcyclohexanedicarboxylic acid It is characterized by comprising. When the mixture is composed of the cis-type alicyclic dicarboxylic acid compound and the trans-type alicyclic dicarboxylic acid compound, as described above,
Alicyclic dicarboxylic acid compounds and trans alicyclic dicals
It is necessary to constitute this with a boronic acid compound.

The above-mentioned resin matrix material, organic low-molecular substance, and a mixture of a cis-type alicyclic dicarboxylic acid compound and a trans-type alicyclic dicarboxylic acid compound are mixed with methyl ethyl ketone and methyl isobutyl ketone. , Chloroform, ethanol, benzene, toluene,
An organic low-molecular substance dissolved in an organic solution such as tetrahydrofuran or carbon tetrachloride and coated on a support described below and dried, or a uniformly compatible organic low-molecular substance;
The cis-type alicyclic dicarboxylic acid compound, and the trans-type alicyclic dicarboxylic acid compound are dispersed in a fine particle form in a solution in which the resin base material is dissolved to obtain a dispersion, and the dispersion is obtained. The recording layer is coated on a support and dried to form the recording layer whose transparency reversibly changes depending on temperature.

In this case, the same kind of cis type and trans type are contained in the organic low molecular weight material dispersed in the resin matrix.
Composed of an alicyclic dicarboxylic acid compound of the type
The ratio of the type: trans type is 8: 2 to 2:
The mixture set in the range of 8 is added, and the temperature at which the addition of the mixture causes the eutectic temperature of the organic low-molecular substance and the mixture to be heated when heated is lower than that of the organic low-molecular substance alone. In addition, the degree of increase is significantly greater than when the above-mentioned aliphatic saturated dicarboxylic acid is applied, and when either the cis-type or the trans-type alicyclic dicarboxylic acid compound is applied. As compared with the above, the transparency temperature range can be greatly expanded.

Here, the mixing ratio of the cis-type alicyclic dicarboxylic acid compound and the trans-type alicyclic dicarboxylic acid compound constituting the mixture in the cis-form: trans-form is as described above. 8: 2 to 2: 8
Although it is set within the range, as is clear from the results of the examples described below, when the mixing ratio is the same, the above-mentioned transparentizing temperature range becomes the maximum.

The invention according to claim 3 is made based on such technical reasons.

That is, the invention according to claim 3 corresponds to claim 1
Or assuming the thermosensitive recording medium according to 2, the mixture is
It is characterized by being composed of a cis-type alicyclic dicarboxylic acid compound and a trans-type alicyclic dicarboxylic acid compound mixed at the same ratio.

Next, the addition ratio of the above-mentioned mixture composed of the cis-type alicyclic dicarboxylic acid compound and the trans-type alicyclic dicarboxylic acid compound is 2 parts with respect to the total amount of this mixture and the above-mentioned organic low molecular weight substance. It is desirable to set the weight% to 30% by weight. If the amount is less than 2% by weight, the effect of adding the mixture is insufficient, so that the clarification temperature range cannot be sufficiently expanded. On the other hand, if the amount exceeds 30% by weight, the clarification temperature range significantly increases, but the ratio of the mixture increases. This causes a problem that the turbidity of the recording layer is reduced.

The invention according to claim 4 has been made based on such technical grounds.

That is, the invention according to claim 4 is based on the thermosensitive recording medium according to claim 1, 2 or 3, and comprises the cis-type alicyclic dicarboxylic acid compound and the trans-type alicyclic dicarboxylic acid compound. The addition ratio of the mixture is 2% by weight to 30% by weight based on the total amount of the mixture and the organic low-molecular substance.
% By weight.

The mixing ratio of the organic low-molecular substance to which the above-mentioned mixture was added and the resin base material was 1: 1 by weight.
2-1 is set to 1: 6.

Thus, in this technical means,
The advantage that the temperature range for clearing can be greatly expanded as compared with the conventional means disclosed in JP-A-2-1363 or JP-A-3-2089 to which the above-mentioned aliphatic saturated dicarboxylic acid is applied. And the addition ratio of a mixture of a cis-type alicyclic dicarboxylic acid compound and a trans-type alicyclic dicarboxylic acid compound is 2% by weight to 30% by weight.
Even if it is as small as about weight%, it functions sufficiently and has an advantage that the turbidity of the recording layer is hardly reduced.

Here, for the purpose of improving the optical properties of the recording layer, a dye, an ultraviolet absorber, an infrared absorber or the like may be added to the recording layer in the same manner as in the prior art, or the plasticity and surface smoothness of the recording layer may be improved. For the purpose of improving the properties, a plasticizer, a surfactant or the like may be added as in the conventional case.

Further, a protective layer made of a fluorine-based resin, a silicone-based resin or the like may be provided on the recording layer in the same manner as in the prior art in order to improve the printing suitability and to improve the repetitive rewriting resistance. In this case, an acryloyl group (—OOC—CH ＝ CH ₂ ) or a methacryloyl group (—OOC—CH) is added to the terminal or side chain instead of the organic material such as the above-mentioned fluororesin which is dissolved or dispersed in an organic solvent and applied. = CHCH ₃ ) may be applied with an acrylic resin which is cured by irradiating an aqueous emulsion mainly containing an acrylic oligomer having (CHCH ₃ ) with ultraviolet rays or an electron beam. By using such an aqueous material as the material for the protective layer, there is no possibility that the oligomer or the aqueous solvent will permeate into the recording layer when forming the protective layer, as compared with the case where the organic material is applied. Therefore, there is an advantage that the initial dispersion state of the organic low-molecular substance in the recording layer can be maintained before and after the formation of the protective layer.

Here, as the acrylic oligomer, those modified with urethane, polyester, polyether, epoxy, silicone or the like as described below can be applied. Hereinafter, each will be described.

(1) Polyurethane acrylate Polyurethane acrylate includes polyol (polyester type and polyether type), diisocyanate,
A polymer (oligomer) obtained by reacting an acrylate or methacrylate having a hydroxyl group,
For example, the following compounds may be mentioned.

[0036]

Embedded image (2) Polyester acrylate Polyester acrylate is a polymer (oligomer) obtained by introducing an acryloyl group or a methacryloyl group into a polyester synthesized from a polyhydric alcohol and a polybasic acid.
For example, the following compounds can be applied.

[0037]

Embedded image (3) Epoxy acrylate Epoxy acrylate is a polymer (oligomer) synthesized by reacting an acrylic resin or methacrylic acid with an epoxy resin, for example, bisphenol A shown below.
Type, F type, S type, phenol novolak type, alicyclic type epoxy acrylate or epoxy methacrylate.

[0038]

Embedded image (4) Silicone resin acrylate Silicone resin acrylate is a polymer (oligomer) in which an acryloyl group or a methacryloyl group is introduced into polysiloxane, and for example, the following compounds can be applied.

[0039]

Embedded image Here, the above-mentioned hydroxyl-modified vinyl chloride-vinyl acetate copolymer and an isocyanate compound are used as the resin base material of the recording layer, and the refraction between an organic low-molecular substance and a cis-type or trans-type alicyclic dicarboxylic acid compound. When a thermosetting resin with good transparency and incompatibility with similar ratios is used, this thermosetting resin has excellent heat resistance and mechanical strength, and also adheres to a support such as a plastic sheet or paper. Because of the good properties, the thermal degradation of the recording layer is less likely to occur than when the thermoplastic resin is applied to the resin base material, and the initial dispersion state of the organic low-molecular substance in the recording layer can be maintained for a long time. Becomes Therefore, there is an advantage that a decrease in the degree of white turbidity due to thermal deterioration of the recording layer can be prevented, the rewriting durability can be improved, and the formation of the protective layer can be omitted.

However, when a thermosetting resin was used as the resin base material of the recording layer, the result was lower than in the case where a thermoplastic resin was used, as is clear from the results of the following Examples and Comparative Examples. There is an adverse effect that the transparentization temperature range is narrowed.

However, in this technical means, the transparentizing temperature range can be greatly expanded as compared with the conventional method, so that even if the transparentizing temperature range is narrowed with the application of the thermosetting resin, the transparent method of the conventional method is used. The temperature is still larger than the activation temperature range, and therefore does not hinder the characteristics of the thermosensitive recording medium at all.

The invention according to claim 5 is based on such technical grounds, and is based on the heat-sensitive recording medium according to claim 1, 2, 3 or 4, wherein the resin base material is a hydroxyl-modified vinyl chloride. -It is characterized by being constituted by a thermosetting resin comprising a vinyl acetate copolymer and an isocyanate compound.

In this technical means, the same support as the conventional one can be applied as it is to the support for the recording layer and the like. For example, a transparent plastic film or sheet, or a colorant such as a dye or pigment is mixed. A plastic film or sheet, a plastic film or sheet laminated with a coloring layer composed of a paint or ink containing a dye or a pigment, and a light-reflective metal layer such as aluminum, tin, silver, magnesium, chromium, and nickel. The provided plastic film, sheet or paper can be used. As a specific example of the plastic film or sheet, a material group having excellent heat resistance, transparency, and mechanical strength such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and polyparabanic acid can be given.

When a light-reflective metal layer is formed on the above-mentioned plastic film, sheet, paper or the like, the purpose is to enhance the adhesive force between the light-reflective metal layer and the recording layer formed thereon. An adhesive layer made of an adhesive is interposed. As the adhesive, a polyester resin, an acrylic polyol resin, a vinyl chloride-vinyl acetate copolymer resin having a phosphate ester group, and the like, which are conventionally applied, can be used. In addition to these materials, a thermoplastic polyparabanic acid resin represented by the following structural formula, which is excellent in heat resistance, solvent resistance, adhesion to metal, and the like, may be applied. In other words, when this polyparabanic acid resin is applied, the resin has almost no heat shrinkage effect when forming the adhesive layer, so that cracks and pinholes are not formed in the light-reflective metal layer and the reflection density is reduced. Can be prevented, and
This resin is dissolved in an organic solvent such as tetrahydrofuran,
Since it has a property that it is not easily swelled, there is almost no danger that the organic solvent for forming the recording layer infiltrates into the adhesive layer, and it is possible to further prevent a decrease in the reflection density in the light-reflective metal layer. Since it has excellent adhesion to metal, it has an advantage that the phenomenon of peeling of the adhesive layer from the light-reflective metal layer can be prevented.

[0045]

Embedded image

[0046]

According to the first and second aspects of the present invention, the same kind of cis-type organic compound is dispersed in the organic low-molecular substance dispersed in the resin base material.
And a trans-type alicyclic dicarboxylic acid compound
And cis-type: trans-type in proportion by weight
Since the mixture set within the range of 8: 2 to 2: 8 is added, the temperature at which the low-molecular organic substance and the above-mentioned mixture are eutectic when the mixture is heated by the addition of the mixture is organic. It is higher than the case of the low molecular weight substance alone, and the degree of the increase is remarkably larger than that in the case where the conventional aliphatic saturated dicarboxylic acid is applied. Since it is larger than the case where only a dicarboxylic acid compound is applied, the transparentization temperature range can be dramatically expanded.

According to the third aspect of the present invention, the mixture is composed of a cis-type alicyclic dicarboxylic acid compound and a trans-type alicyclic dicarboxylic acid compound mixed at the same ratio. Therefore, it is possible to further expand the transparentization temperature range.

On the other hand, according to the fourth aspect of the present invention, the addition ratio of the mixture of the cis-type alicyclic dicarboxylic acid compound and the trans-type alicyclic dicarboxylic acid compound is such that this mixture and the organic low molecular weight compound are mixed. It is set at 2% by weight to 30% by weight based on the total amount of the substance, and it is possible to sufficiently expand the clearing temperature range even when the addition ratio of the mixture is lower than that in the prior art using an aliphatic saturated dicarboxylic acid. Since the addition ratio of the mixture of the cis-type alicyclic dicarboxylic acid compound and the trans-type alicyclic dicarboxylic acid compound decreases, it is possible to prevent the turbidity of the recording layer from lowering.

Further, according to the invention of claim 5, the resin base material is composed of a thermosetting resin composed of a hydroxyl-modified vinyl chloride-vinyl acetate copolymer and an isocyanate compound. It has excellent heat resistance and mechanical strength, and also has good adhesiveness to a support such as a plastic sheet or paper, so that the recording layer is less likely to be thermally degraded than when a thermoplastic resin is applied to the resin base material. Since it is possible to prevent a decrease in the degree of white turbidity in the recording layer due to the thermal deterioration, it is possible to improve the rewriting resistance and to omit the formation of the protective layer.

[0050]

Embodiments of the present invention will be described below in detail.

The parts and percentages of the components described in Examples and Comparative Examples are all parts by weight and% by weight.

Example 1 A heat-sensitive recording medium according to this example includes a support 1 made of a transparent polyester sheet as shown in FIG. 1, an anchor layer 2 provided on the support 1, A light-reflective metal layer 3 provided on the anchor layer 2 and an adhesive layer 4 provided on the light-reflective metal layer 3
And a recording layer 5 provided on the adhesive layer 4 and a protective layer 6 provided on the recording layer 5 to form a main part.

The thermosensitive recording medium is manufactured through the following steps.

That is, a composition for an anchor layer having the following composition was applied on a support 1 made of a transparent polyester sheet having a thickness of 150 μm with a wire bar, dried at 100 ° C. for 5 minutes, and thermally cured to dry. An anchor layer 2 having a thickness of 1.5 μm is formed, and aluminum is vacuum-deposited on the anchor layer 2 to form a light-reflective metal layer 3 having a thickness of 500 Å. 3 was coated with a composition for an adhesive layer having the following composition in the same manner using a wire bar, and dried at 90 ° C. for 5 minutes to give a dry film thickness of 0.5 μm.
m of the adhesive layer 4 was formed.

Next, the following uniformly dissolved recording layer composition is applied onto the adhesive layer 4 with a wire bar.
After drying at 110 ° C. for 3 minutes to form a recording layer 5 having a dry film thickness of 9 μm, a composition for a protective layer having the following composition was applied on the recording layer 5 using a wire bar, and the coating was performed at 90 ° C. for 3 minutes. After drying, the support 1 was placed on a conveyor and moved at a speed of 10 m / min, and a height of 10 m / min.
High pressure mercury lamp (80W / cm, ozone focusing type)
The composition for a protective layer was light-cured to form a protective layer 6 having a cured film thickness of 2.5 μm to obtain a thermosensitive recording medium.

(Composition for anchor layer) Polyester resin (manufactured by Toyobo Co., Ltd., trade name: Byron # 200) 10 parts Isocyanate 0.1 part (curing agent trade name, duranate 24A-100 manufactured by Asahi Kasei Corporation) triethylenediamine (curing accelerator) 0.01 part 45 parts toluene 45 parts 2-butanone 45 parts (composition for adhesive layer) 10 parts polyparaban acid tree (trade name PPA-D manufactured by Nitto Kagaku)

Embedded image Acetone 80 parts Dioxane 10 parts (Composition for recording layer) Behenic acid 90 parts Mixture of cis- and trans-type alicyclic dicarboxylic acid compounds 10 parts (However, 1,4-ciscyclohexanedicarboxylic acid: 8 parts 1,4 -Transcyclohexanedicarboxylic acid: 2 parts) Vinyl chloride-vinyl acetate copolymer 300 parts (trade name: SREC C, manufactured by Sekisui Chemical Co., Ltd.) Toluene 300 parts Tetrahydrofuran 1200 parts (Composition for protective layer) Polyfunctional polyester acrylate 100 parts Emulsion (Solid content 40% by weight) (Toa Gosei Chemical Co., Ltd., trade name M-8060 emulsion) Lubricant (Special polymer silicone resin solution, solid content 50% by weight, 5 parts BYK-Japan trade name, BYK-301) Photoinitiator 2 (Product name Irgacure 651 manufactured by Nippon Ciba Geigy) Example 2] The recording layer composition of the recording layer composition having the following composition by applying a wire bar coated on the adhesive layer 4, cured film thickness at 100 ° C. 5 minutes dried and thermally cured 9
It is almost the same as the thermosensitive recording medium according to Example 1 except that a recording layer 5 of μm was formed.

(Composition for Recording Layer) Behenic acid 90 parts Mixture of cis- and trans-type alicyclic dicarboxylic acid compounds 10 parts (However, 1,4-ciscyclohexanedicarboxylic acid: 8 parts 1,4-transcyclohexane Dicarboxylic acid: 2 parts) Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 300 parts (trade name: SREC A, manufactured by Sekisui Chemical Co., Ltd.) Isocyanate 30 parts (curing agent, duranate 24A-100, manufactured by Asahi Kasei Corporation) triethylenediamine ( (Curing accelerator) 3 parts Toluene 300 parts Tetrahydrofuran 1200 parts [Example 3] For behenic acid and the above mixture in the recording layer composition, behenic acid was 90 parts, and cis- and trans-type alicyclic dicarboxylic acid compounds were used. A mixture (provided that 1,4-ciscyclohexanedicarboxylic acid: 6 parts, 1,4-trans B hexane dicarboxylic acid: 4 parts) are substantially the same and the heat sensitive recording medium according to Example 2 except that the applied instead of 10 parts.

Example 4 With respect to behenic acid and the above mixture in the recording layer composition, 90 parts of behenic acid and a mixture of cis- and trans-type alicyclic dicarboxylic acid compounds (provided that
1,4-ciscyclohexanedicarboxylic acid: 5 parts, 1,
4-transcyclohexanedicarboxylic acid: 5 parts)
It is substantially the same as the heat-sensitive recording medium according to Example 2 except that it is applied in place of 0 part.

Example 5 A mixture of behenic acid and 90% of behenic acid in a composition for a recording layer, and a mixture of cis- and trans-type alicyclic dicarboxylic acid compounds (provided that
1,4-ciscyclohexanedicarboxylic acid: 4 parts, 1,
4-transcyclohexanedicarboxylic acid: 6 parts)
It is substantially the same as the heat-sensitive recording medium according to Example 2 except that it is applied in place of 0 part.

Example 6 A mixture of behenic acid and 90% of behenic acid in a composition for a recording layer, and a mixture of cis- and trans-type alicyclic dicarboxylic acid compounds (provided that
1,4-ciscyclohexanedicarboxylic acid: 2 parts, 1,
4-transcyclohexanedicarboxylic acid: 8 parts)
It is substantially the same as the heat-sensitive recording medium according to Example 2 except that it is applied in place of 0 part.

Comparative Example 1 A recording layer composition having the following composition was applied on a 50 μm-thick polyester film on which aluminum was deposited by a wire bar, and dried by heating to form a recording layer having a thickness of about 15 μm. On the recording layer, an intermediate layer composition having the following composition was applied with a wire bar and dried by heating to form an intermediate layer having a thickness of about 1 μm.

Next, a butyl acetate solution of a urethane acrylate-based UV-curable resin was applied on the intermediate layer with a wire bar, dried by heating, and irradiated with UV light for 5 seconds using an 80 W / cm UV lamp for about 5 seconds. A 2 μm protective layer was formed to obtain a thermosensitive recording medium.

(Composition for recording layer) Behenic acid 50 parts Eicosane diacid (aliphatic saturated dicarboxylic acid) 50 parts Vinyl chloride-vinyl acetate copolymer 250 parts Di (2-ethyl-hexyl) phthalate 30 parts Tetrahydrofuran 2000 Part (composition for intermediate layer) Polyamide resin 10 parts Methyl alcohol 90 parts [Comparative Example 2] This is substantially the same as the heat-sensitive recording medium according to Comparative Example 1 except that the following recording layer composition was applied.

(Composition for Recording Layer) Behenic acid 50 parts Eicosane diacid (aliphatic saturated dicarboxylic acid) 50 parts Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 300 parts (trade name SLEKK A manufactured by Sekisui Chemical Co., Ltd.) Isocyanate 30 parts (Asahi Kasei Co., Ltd. curing agent duranate 24A-100) Triethylenediamine (curing accelerator) 3 parts Toluene 300 parts Tetrahydrofuran 1200 parts [Comparative Example 3] Except that the following recording layer composition was applied This is substantially the same as the thermosensitive recording medium according to the first embodiment.

(Composition for recording layer) Behenic acid 90 parts Alicyclic dicarboxylic acid compound 10 parts (However, 1,4-ciscyclohexanedicarboxylic acid: 10 parts 1,4-transcyclohexanedicarboxylic acid: 0 parts) Vinyl chloride -300 parts of vinyl acetate copolymer (trade name: SREC C, manufactured by Sekisui Chemical Co., Ltd.) 300 parts of toluene 1200 parts of tetrahydrofuran [Comparative Example 4] Thermal recording according to Example 1 except that the following composition for a recording layer was applied. It is almost the same as the medium.

(Composition for Recording Layer) Behenic acid 90 parts Alicyclic dicarboxylic acid compound 10 parts (However, 1,4-ciscyclohexanedicarboxylic acid: 10 parts 1,4-Transcyclohexanedicarboxylic acid: 0 part) Vinyl chloride -Vinyl acetate-vinyl alcohol copolymer 300 parts (Sekisui Chemical Co., Ltd., trade name ESLEC A) Isocyanate 30 parts (Asahi Kasei Co., Ltd. hardener trade name duranate 24A-100) triethylenediamine (curing accelerator) 3 parts toluene 300 Part: 1200 parts of tetrahydrofuran “Comparative test” (1) Transparency temperature range Next, the heat-sensitive recording media according to Examples 1 to 6 and Comparative Examples 1 to 4
In order to compare the transparentization temperature range of the heat-sensitive recording medium according to the above, a comparative test as described below was performed.

The recording layers of the thermosensitive recording media according to the examples and the comparative examples obtained as described above were all formed in a cloudy state.

First, each of the obtained thermosensitive recording media is heated stepwise from 65 ° C. in steps of 1 degree and cooled to room temperature, and then reflected by an optical reflection densitometer (Macbeth optical densitometer RD-514) from above. Each density (optical density) was measured.

For the heat-sensitive recording media according to each of the examples and comparative examples, the reflected light from the light-reflective metal layer made of aluminum was measured.

The temperature at which the reflection density exceeded 1.0 was recorded as the clearing temperature, and the clearing temperature range and the clearing temperature range were measured from these data.

The results are shown in Table 1 below.

(2) Evaluation of repeated rewriting resistance Example 2 in which a thermosetting resin was used as a resin base material
A rewriting resistance test was repeatedly performed on the heat-sensitive recording medium according to Comparative Examples 3 and 6 and the heat-sensitive recording medium according to Comparative Example 3 in which a thermoplastic resin was used as a resin base material.

In addition, using a "card reader / writer KU-400" manufactured by Kyushu Matsushita Electric as an evaluation machine, printing conditions were as follows:
0.5 mj / dot (cloudy state), erase condition: 0.2 m
Printing / erasing was repeated at j / dot (transparent state), and the print density (white turbidity) was measured every 20 times (but every 10 times in Comparative Example 3) using a Macbeth optical densitometer RD-514. The results are shown in the graph of FIG.

[0074]

[Table 1] "Evaluation" (1) Transparency temperature range In Table 1, Example 1 (64 ° C.) and Example 2 (35
° C), Comparative Example 1 (19 ° C) and Comparative Example 2 (8 ° C), and
As is clear from the comparison of the “clearing temperature range” in Comparative Example 3 (50 ° C.) and Comparative Example 4 (25 ° C.), when a thermosetting resin is used as a resin base material, the resin is compared with a thermoplastic resin. It can be confirmed that the transparency temperature range (width of the transparency temperature range) becomes narrow. However, in the heat-sensitive recording medium according to Example 2, although the thermosetting resin was used as the resin base material, the transparency temperature range was 35 ° C., and the ratio between the cis type and the trans type was changed. In the thermal recording media according to Examples 3 to 6, the transparency temperature range was 69 ° C., 77 ° C.
The values were as large as ° C., 68 ° C., and 64 ° C., and it was also confirmed that the characteristics as a recording medium were not affected at all.

Next, an alicyclic dicarboxylic acid compound (1,
Comparative Example 1 (4-cyclohexanedicarboxylic acid) to which the thermosensitive recording medium according to Example 1 (64 ° C.) and Example 2 (35 ° C.) was applied, and aliphatic saturated dicarboxylic acid (eicosane diacid) was applied. 19 ° C.) and Comparative Example 2 (8 ° C.)
As is clear from the comparison with the heat-sensitive recording medium according to the present invention, it can be confirmed that the transparency temperature range has been dramatically expanded by applying the alicyclic dicarboxylic acid compound instead of the aliphatic saturated dicarboxylic acid. Was.

Therefore, it is easy to set the heating temperature of the thermal head or the like within the transparentizing temperature range at a high speed by expanding the transparentizing temperature range.
It was confirmed that a transparent image could be formed relatively easily on the basis of.

Further, in the heat-sensitive recording medium according to each of the examples, the clearing temperature range was dramatically expanded even though the addition ratio of the alicyclic dicarboxylic acid compound to 90 parts of behenic acid was 10 parts. (In Comparative Examples 1 and 2, 50 parts of eicosane diacid were added to 50 parts of behenic acid.) Therefore, the addition ratio of the dicarboxylic acid compound which easily reduced the turbidity of the recording layer by the addition was determined. It was also confirmed that, since the recording layer could be reduced, the recording layer had an advantage of preventing a decrease in the white turbidity.

Further, the heat-sensitive recording media according to Examples 1 to 6 to which a mixture of a cis type alicyclic dicarboxylic acid compound and a trans type alicyclic dicarboxylic acid compound was applied,
As is clear from the comparison with the heat-sensitive recording media according to Comparative Examples 3 and 4, in which only the cis-type alicyclic dicarboxylic acid compound was applied, the transparency temperature range could be further expanded by applying the mixture. Was confirmed. In particular, Example 4
In the heat-sensitive recording medium according to the cis-type alicyclic dicarboxylic acid compound and trans-type alicyclic dicarboxylic acid compound, since the transparency temperature range shows a maximum value of 77 ° C. as compared with the other examples. It was also confirmed that the effect was increased when the mixing ratio with was the same.

Table 2 below shows data on the maximum transparent density and the maximum cloudiness density of the recording layer of the heat-sensitive recording medium according to each of the examples.

As is apparent from this data, since the decrease in the degree of white turbidity in the recording layer is small, the contrast between the image area and the non-image area hardly decreases in the heat-sensitive recording medium according to each embodiment. It was also confirmed.

[0081]

[Table 2] (2) Evaluation of repetitive rewriting resistance In the thermosensitive recording media according to Examples 2 and 6 in which a thermosetting resin was applied as the resin base material, as shown in FIG. Although it did not increase (that is, the maximum white turbid density during printing did not decrease), its repetitive rewriting resistance was good. However, in the thermosensitive recording medium according to Comparative Example 3 in which a thermoplastic resin was used as a resin base material, 20 times. It was confirmed that the reflection density was remarkably increased by repetition of about 40 times, and the maximum white turbid density during printing was reduced.

[0082]

According to the first and second aspects of the present invention, the same
Kinds of cis and trans alicyclic dicarboxylic oxidations
And cis-form: trans-form
The addition of a mixture in a weight ratio within the range of 8: 2 to 2: 8 makes the eutectic temperature of the organic low-molecular substance and the mixture low when the mixture is heated. And the extent of the increase is significantly greater than when a conventional aliphatic saturated dicarboxylic acid is applied, and only one of the cis- or trans-type alicyclic dicarboxylic acid compounds is applied. Since it is larger than that in the case where it is used, it is possible to drastically expand the transparency temperature range.

According to the third aspect of the present invention, the mixture is composed of a cis-type alicyclic dicarboxylic acid compound and a trans-type alicyclic dicarboxylic acid compound mixed in the same ratio. Therefore, it is possible to further expand the temperature range for the transparency.

On the other hand, according to the fourth aspect of the present invention, the clearing temperature range can be sufficiently expanded even if the addition ratio of the mixture is low as compared with the prior art using an aliphatic saturated dicarboxylic acid. Since the addition ratio of the mixture of the cis-type alicyclic dicarboxylic acid compound and the trans-type alicyclic dicarboxylic acid compound decreases, it is possible to prevent a decrease in the white turbidity of the recording layer.

Therefore, it is easy to set the heating temperature of the heating means such as a thermal head at a high speed within the range of the transparency temperature, so that a transparent image can be formed on a white background (cloudy state) as a background or a transparent background ( It is possible to easily form a cloudy image with a transparent state) as a background, which has the effect of expanding the applicable range of this type of heat-sensitive recording medium, and reduces the contrast between the image area and the non-image area. It is difficult to improve the recording image quality.

Further, according to the invention of claim 5, the resin base material is composed of a thermosetting resin composed of a hydroxyl-modified vinyl chloride-vinyl acetate copolymer and an isocyanate compound. Since it has excellent heat resistance and mechanical strength, and also has good adhesiveness to a support such as a plastic sheet or paper, the recording layer is less likely to be thermally degraded than when a thermoplastic resin is applied to the resin base material.

Accordingly, since it is possible to prevent a decrease in white turbidity due to thermal deterioration of the recording layer, it is possible to improve the rewriting resistance and to omit the formation of the protective layer.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view of a thermosensitive recording medium according to an embodiment.

FIG. 2 shows a thermosensitive recording medium according to Examples 2 and 6 and Comparative Example 3.
FIG. 4 is a graph showing the relationship between the number of prints and the reflection density of the thermosensitive recording medium according to the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support body 2 Anchor layer 3 Light reflective metal layer 4 Adhesive layer 5 Recording layer 6 Protective layer

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Watanabe 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (56) References JP-A-5-139053 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) B41M 5/36

Claims (5)

(57) [Claims] 1. A rewritable thermosensitive recording medium comprising a recording layer mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material, the recording layer of which reversibility changes depending on temperature. in, the dispersed organic low molecular substance in the above resin base material, the same
Kinds of cis and trans alicyclic dicarboxylic oxidations
And cis-form: trans-form
A rewritable thermosensitive recording medium, wherein a mixture set in a weight ratio of 8: 2 to 2: 8 is added. 2. A mixture comprising 1,2-ciscyclopropanedicarboxylic acid, 1,2-ciscyclobutanedicarboxylic acid, 1,2-ciscyclopentanedicarboxylic acid, 1,2
Cis-type selected from -ciscyclohexanedicarboxylic acid, 1,3-ciscyclobutanedicarboxylic acid, 1,3-ciscyclopentanedicarboxylic acid, 1,3-ciscyclohexanedicarboxylic acid, and 1,4-ciscyclohexanedicarboxylic acid An alicyclic dicarboxylic acid compound of
1,2-transcyclopropanedicarboxylic acid, 1,2
-Transcyclobutanedicarboxylic acid, 1,2-transcyclopentanedicarboxylic acid, 1,2-transcyclohexanedicarboxylic acid, 1,3-transcyclobutanedicarboxylic acid, 1,3-transcyclopentanedicarboxylic acid, 1,3-transcyclohexane 2. A rewritable thermosensitive recording medium according to claim 1, comprising a dicarboxylic acid and a trans-type alicyclic dicarboxylic acid compound selected from 1,4-transcyclohexanedicarboxylic acid. 3. The method according to claim 1, wherein the mixture is composed of a cis-type alicyclic dicarboxylic acid compound and a trans-type alicyclic dicarboxylic acid compound mixed in the same ratio. Or a rewritable thermosensitive recording medium according to 2. 4. The addition ratio of said mixture comprising a cis-type alicyclic dicarboxylic acid compound and a trans-type alicyclic dicarboxylic acid compound is 2% by weight based on the total amount of said mixture and said organic low-molecular substance. 4. The rewritable thermosensitive recording medium according to claim 1, wherein the rewritable thermosensitive recording medium is set to about 30% by weight. 5. The resin base material according to claim 1, wherein the resin base material is made of a thermosetting resin comprising a hydroxyl-modified vinyl chloride-vinyl acetate copolymer and an isocyanate compound. A rewritable thermosensitive recording medium according to the description.