JP2001047741A - Heat-sensitive multiple copy sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive multiple copy sheet for obtaining a recorded image having excellent recording density, small bleeding or skip in an entire recording sheet. SOLUTION: The heat-sensitive multiple copy sheet comprises (a) an upper leaf recording sheet having a heat-sensitive recording layer 12 on a front surface of a base material sheet 11 and a thermal transfer layer 13 on a rear surface, (b) at least one intermediate leaf recording sheet 20 having a thermal transfer receiving layer 22 or a heat-sensitive recording layer on a front surface of a base sheet 21 and a thermal transfer layer 23 on a rear surface, and (c) a lower leaf recording sheet 30 having a thermal transfer receiving layer 32 on a front surface of a base material sheet 31 in such a manner that a shrinkage point of the layer 13 is higher than that of the layer 23 of the sheet 20 brought into contact with the sheet 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a color former, and more particularly, a heat-sensitive recording image can be simultaneously obtained on three or more sheets, especially about three to four sheets. The present invention relates to a heat-sensitive multiplex copy sheet.

[0002]

2. Description of the Related Art A thermosensitive recording medium is known which utilizes a color development reaction between a leuco dye and a color former and reacts both coloring substances with heat energy from a thermal head to obtain a recorded image. Such a thermosensitive recording medium is relatively inexpensive, and its recording equipment is compact and easy to maintain, so that it is used not only as a recording medium for facsimile machines and various computers but also in a wide range of fields.

In particular, since a thermal recording medium has been used in the form of a thermal multiple copy sheet, for example, as a delivery note, a single thermal recording has the same recording density and the same sharpness on a plurality of sheets. The need for a heat-sensitive multiplex copy sheet capable of recording having suppressed blurring has increased.

JP-A-57-96895 discloses a heat-sensitive multi-copy sheet in which a heat-transferable organic compound having a melting point of 30 to 110 ° C. and a colorant are contained in a thermal transfer layer of an upper leaf recording sheet. As described above, the recording density of each of the plurality of sheets was high, and clear thermal recording images were not obtained.

Further, Japanese Patent Publication No. 51-29948 discloses that a plurality of heat-sensitive recording materials having a heat-sensitive recording layer containing a leuco dye and a colorant on a support are laminated, and the heat-sensitive recording layer of the upper heat-sensitive recording material is laminated. Is described in which the melting point is higher than that of the lower layer. However, at present, clear thermal recording images are not obtained on all of the sheets having a high recording density.

That is, in these conventional thermosensitive multiplex copying sheets, the recorded image on the lower leaf recording sheet generally has a low recording density and blur, and if the applied energy is increased to solve this defect, the recording density of the middle leaf recording sheet is reduced. There are drawbacks such as bleeding of the recorded image, and it has been difficult to form a recorded image having the same recording density and sharpness for all of the plurality of recording sheets.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive multiplex copy sheet which is excellent in recording density on all of a large number of recording sheets and which can obtain a heat-sensitive recorded image with little blurring or blurring. .

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the contraction point of the thermal transfer layer of the upper leaf recording sheet was set to the value of the middle leaf recording sheet in contact with the lower leaf recording sheet. By making it higher than the contraction point of the thermal transfer layer,
The inventors have found that the above-mentioned object is achieved, and have completed the present invention.

That is, the present invention provides (a) a heat-sensitive recording layer containing a leuco dye, a coloring agent and an adhesive on the front surface of a base sheet, and a leuco dye and a heat-fusible organic material on the back surface. Upper leaf recording sheet having a thermal transfer layer containing a compound, (b) on the front side of a base sheet, a thermal transfer receiving layer containing a colorant and an adhesive, or a leuco dye, a colorant and an adhesive At least one mid-leaf recording sheet having a thermal transfer layer containing a leuco dye and a heat-fusible organic compound on the back side, and (c) coloring on the front side of the base sheet. Including a lower leaf recording sheet having a thermal transfer receiving layer containing an agent and an adhesive, the upper leaf recording sheet, the at least one middle leaf recording sheet and the lower leaf recording sheet are stacked in this order, and, Of the two adjacent recording sheets, Also in displacement, the rear surface of the recording sheet in the above, has front surface facing the recording sheet under, upper lobe thermal transfer layer of the shrinkage point of the recording sheet (JI
SK 0064) is higher than the shrinking point of the thermal transfer layer of the middle recording sheet that is in contact with the lower recording sheet (based on the JIS K 0064 melting range measurement method). A copy sheet is provided.

In this specification, the terms "front surface" and "back surface" are used as having the following meanings.
In the upper leaf recording sheet, the surface on which the heat-sensitive recording layer is provided is referred to as “front surface”, and the surface on the opposite side where the thermal transfer layer is provided is referred to as “back surface”. In the middle leaf record sheet,
The surface facing the direction of the upper leaf recording sheet is called a "front surface", and the surface on the opposite side is called a "back surface". In the lower-leaf recording sheet, the surface facing the direction of the upper-leaf recording sheet is called a “front surface”, and the surface on the opposite side is called a “back surface”. Also, the direction of the upper leaf recording sheet is “up”
, And the direction of the lower leaf recording sheet is referred to as “down”.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, which is a schematic diagram showing an example of the arrangement of the upper leaf recording sheet, the middle leaf recording sheet, and the lower leaf recording sheet according to the present invention. The heat-sensitive multiplex copy sheet of the present invention comprises an upper leaf recording sheet 10, a middle leaf recording sheet 20, and a lower leaf recording sheet 30.
Is included.

A heat-sensitive recording layer 12 is formed on the front surface of the base sheet 11 of the upper leaf recording sheet 10, and a heat transfer layer 13 is formed on the back surface of the base sheet 11.

A heat transfer receiving layer or a heat-sensitive recording layer 22 is formed on the front surface of the base sheet 21 of the middle leaf recording sheet 20, and a heat transfer layer 23 is formed on the back surface of the base sheet 21. .

On the front surface of the base sheet 31 of the lower leaf recording sheet 30, a thermal transfer receiving layer 32 is formed.

The heat-sensitive multiplex copy sheet of the present invention is not limited to a single sheet as shown in FIG.
As shown in FIG. 2, a case where a plurality of middle leaf recording sheets are stacked between the upper leaf recording sheet 10 and the lower leaf recording sheet 30 is also included. In FIG. 2, the same parts as those shown in FIG. 1 are denoted by the same reference numerals.

According to the present invention, the contraction point of the thermal transfer layer of the upper leaf recording sheet (hereinafter referred to as "contraction point A") is determined by the contraction point of the thermal transfer layer of the middle leaf recording sheet in contact with the lower leaf recording sheet.
The above object is achieved by making the shrinking point A higher than the shrinking point B. In particular, in the present invention, the thermal recording images of all the recording sheets have a high recording density, and the thermal recording images of all the recording sheets both have little blurring or bleeding, and are sharp. The effect of is obtained.

The shrinking point A and the shrinking point B are measured by peeling off the thermal transfer layer of each recording sheet and measuring it according to the melting range measuring method of JIS K0064.

The shrinking point mainly depends on the melting points of the leuco dye and the heat-fusible organic compound in the thermal transfer layer, or their ratio. For example, in order to make the shrink point A higher than the shrink point B, a heat-fusible organic compound having a higher melting point than the heat-fusible organic compound contained in the heat transfer layer of the middle leaf recording sheet is used. To be obtained.

The temperature range of the shrinking point A and the shrinking point B is not particularly limited, but the shrinking point A is preferably about 65 to 130 ° C., particularly preferably about 70 to 90 ° C. When the shrinkage point A is less than 65 ° C., when the unrecorded heat-sensitive multiple recording sheet is stored, each heat transfer receiving layer (or the heat-sensitive recording layer is formed on the front surface of the middle leaf recording sheet,
In the heat-sensitive recording layer, background fog may occur, and when the temperature exceeds 130 ° C., the recording density of a heat-sensitive recording image may decrease.

The temperature difference between the shrinking points A and B is preferably about 5 to 20 ° C., and particularly preferably about 5 to 15 ° C. When the temperature difference is 5 ° C. or more, the clarity of the heat-sensitive recording image of the middle leaf recording sheet tends to be improved (especially, bleeding is reduced). The density of the thermal recording image on the recording sheet can be made sufficient.

Further, in the present invention, the number of middle leaf recording sheets is not limited to one, and as shown in FIG. 2, two or more middle leaf recording sheets can be used, particularly, about two. in this way,
When two (or more) middle leaf recording sheets are used, the contraction point of the thermal transfer layer of the middle leaf recording sheet closest to the upper leaf recording sheet is the highest, and the contraction point of the thermal transfer layer of the middle leaf recording sheet gradually increases. The contraction point of the thermal transfer layer of the middle leaf recording sheet which is in contact with the lower leaf recording sheet is minimized. For example, when using two sheets of a first middle leaf recording sheet adjacent to the upper leaf recording sheet and a second middle leaf recording sheet adjacent to the first middle leaf recording sheet, the shrinkage point of the thermal transfer layer of each sheet is , The upper leaf recording sheet, the first middle leaf recording sheet, and the second middle leaf recording sheet in this order. However, the contraction point of the thermal transfer layer of the upper recording sheet and the contraction point of the thermal transfer layer of the first middle recording sheet may be the same.

In the case where two or more middle leaf recording sheets are used, the contraction point A of the thermal transfer layer of the upper leaf recording sheet and the contraction point B1 of the thermal transfer layer of the at least one middle leaf recording sheet are also used. Bn (n is equal to the number of middle leaf recording sheets; B1 is the contraction point of the thermal transfer layer of the middle leaf recording sheet in contact with the upper leaf recording sheet, and Bn is the contraction of the thermal transfer layer of the middle leaf recording sheet in contact with the lower leaf recording sheet Is not particularly limited. But,
The shrinking point A is preferably about 65 to 130 ° C.,
About 0 to 90 ° C. is preferable. When the shrinkage point A is less than 65 ° C., when the unrecorded heat-sensitive multiple recording sheet is stored, the heat-sensitive recording layer is formed on each heat transfer receiving layer (or, if the heat-sensitive recording layer is formed on the front surface of the middle leaf recording sheet, Background fog may occur in the layer, and if it exceeds 130 ° C., the recording density of the thermosensitive recording image may decrease.

The temperature difference between the shrinking point A and the shrinking points B1... Bn is preferably 5 ° C. or more as the temperature difference between the two shrinking points of the thermal transfer layers of two adjacent sheets.
It is preferable that the temperature difference between the contraction point A and the contraction point Bn of the middle leaf recording sheet in contact with the lower leaf recording sheet be within 20 ° C. Generally, the temperature difference between the shrinking point A and the shrinking point Bn is preferably about 5 to 20 ° C, particularly preferably about 5 to 15 ° C. Thus, the temperature difference between two adjacent shrinking points is 5 ° C.
(If there are two or more middle leaf recording sheets, the contraction point A may be the same as the contraction point B1 of the thermal transfer layer of the middle leaf recording sheet in contact with the upper leaf recording sheet.) The thermal recording image on the sheet tends to be sharper (in particular, bleeding is reduced), and the shrink point A
And contraction point Bn of the middle leaf recording sheet in contact with the lower leaf recording sheet
Is within 20 ° C., the density of the thermal recording image on the lower leaf recording sheet can be made sufficient.

As a typical means for changing the shrinkage points of a plurality of thermal transfer layers as described above, it is possible to select the type and / or the amount of the heat-fusible organic compound used for each thermal transfer layer. it can.

According to a preferred embodiment of the present invention, the density of the thermal transfer receiving layer or thermal recording layer of the middle recording sheet and the density of the thermal transfer receiving layer of the lower recording sheet are 0.9 to 1.2 g.
/ Cm ³ , preferably 1.0 to 1.1 g / cm ³ , not only the effect of increasing the recording density of the recorded images formed on all the recording sheets, but also the middle leaf recording sheet and the lower leaf recording Both the bleeding and blurring of the thermosensitive recording image formed on the sheet are extremely small, and therefore, in all the recording sheets, the effect of improving the recording density, suppressing bleeding and suppressing the blurring in all points is excellent.

If the density of such a layer is less than 0.9 g / cm ³ , the heat-sensitive recording image may be blurred.
If the density exceeds 2 g / cm ³ , bleeding may occur in the heat-sensitive recorded image.
Outside ³ range, but either the bleeding and blur occur tend to occur relatively more than the other, the recording density is satisfactory in any of the layers.

The density of such a layer is 0.9 to 1.2 g / cm
^Although there are various methods as means for setting ³ , preferably, for example, a leuco dye having an average particle diameter of about 0.2 to 3.0 μm and a color former having an average particle diameter of about 0.2 to 3.0 μm are preferable. 95: 5 to 6 (weight ratio) between the granular material and the adhesive
After using at about 5:35 or forming a thermal transfer receiving layer or a heat-sensitive recording layer, a calendering pressure (for example, a linear pressure of 10 to 100 kg /
cm) can be adjusted to the above density.

As described above, the thermal multiple copy sheet of the present invention comprises an upper leaf recording sheet, at least one middle leaf recording sheet, and a lower leaf recording sheet. Hereinafter, the structure of each of these sheets, that is, the base sheet, the heat-sensitive recording layer (leuco dye, colorant and adhesive), the heat transfer layer (leuco dye and heat-fusible organic compound), and the heat transfer receiving layer (colorant And an adhesive) will be described in detail.

[0029] In the substrate sheet following description, the "Uehamotozai sheet" a base sheet constituting the upper lobe recording sheet, the base sheet constituting the intermediate lobe recording sheet as "mid base sheet", Shitaha recording The base sheet constituting the sheet is abbreviated as “lower leaf base sheet”. These base sheets may be the same for each sheet, but generally the following is preferred.

1) Upper leaf base sheet and middle leaf base sheet As the upper leaf base sheet and the middle leaf base sheet, for example, glassine paper of about ²⁰ to 70 g / m ² , neutral or acidic high quality paper, film, synthetic paper, etc. No. Above all, about 25 to 40 g / m ² , and the tension is 0.9 to 1.3 g.
/ Cm ³ of glassine paper or high quality paper is preferred.

Pigments such as calcium carbonate, kaolin, talc, and aluminum hydroxide having an average particle size of about 0.1 to 15 μm are added to the upper and middle leaf base sheets based on the total solid content of the base sheets. By containing about 20% by weight, the recording sensitivity from the thermal transfer layer to the thermal transfer receiving layer is further increased. The base sheet containing such a pigment can be manufactured according to a known method.

2) Lower Leaf Substrate Sheet As the lower leaf base sheet, a neutral or acidic high quality paper, film, synthetic paper or the like of about 30 to 200 g / m ² can be used. The tension of the lower leaf base sheet is not particularly limited, but is generally preferably about 0.8 to 1.3 g / cm ³ .

In particular, when the lower leaf base sheet is high quality paper,
A pigment having an average particle diameter of about 0.1 to 3 μm and / or an average particle diameter of about 0.1 to 3 μm is provided between the lower leaf base sheet and the thermal transfer receiving layer.
It is preferable to provide an undercoat layer containing hollow particles of about 1 to 3 μm as a main component, or to use a high-ash base paper in which a pigment is internally added to a high quality paper at about 15 to 40% by weight.

As the pigment used in the undercoat layer, J.P.
Oil absorption of 70 to 3 measured according to IS K 5101
About 00 ml / 100 g of an oil-absorbing pigment, for example, calcined kaolin having an average particle size of about 0.5 to 5 μm, amorphous silica, calcium carbonate, magnesium carbonate, and the like can be exemplified. Various known hollow particles such as polystyrene hollow particles and polyvinylidene chloride hollow particles can be exemplified.

The undercoat layer containing the pigment and / or the hollow particles as a main component is formed by, for example, uniformly dispersing the pigment and / or the hollow particles and an adhesive (for example, polyvinyl alcohol) in water as a dispersion medium. An undercoat layer coating solution is applied, for example, in an amount of about 5 to 10 g / m ^{2 on} a dry basis,
It can be formed by drying.

Examples of the pigment to be internally added to the high-quality paper include calcium carbonate, talc, and aluminum hydroxide having an average particle diameter of about 1 to 10 μm.

Leuco Dyes The following are examples of leuco dyes contained in the heat-sensitive recording layer and the thermal transfer layer.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylamino Phthalide, 3-
Diethylamino-7-dibenzylaminofluoran, 3
-Cyclohexylamino-6-chlorofluoran, 3-
Diethylamino-6-methyl-7-chlorofluoran,
3-diethylamino-7-chlorofluoran, 3-diethylamino-7-anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-7 -(M-trifluoromethylanilino) fluoran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7
-Anilinofluoran, 3-di (n-butyl) amino-
6-methyl-7-anilinofluoran, 3-di (n-pentyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-7- (o-chloroanilino)
Fluoran, 3-di (n-butyl) amino-7- (o-
Chloroanilino) fluoran, 3-di (n-butyl) amino-7- (o-fluoroanilino) fluoran, 3-
(N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-
7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3,3-bis [1- (4-
Methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2
-Yl] -4,5,6,7-tetrachlorophthalide,
3,6, -bis (dimethylamino) fluorene-9-spiro-3 ′-(6′-dimethylamino) phthalide, 3-
(N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran, 3- (4
-Dimethylamino) anilino-5,7-dimethylfluorane, etc. Of course, the present invention is not limited to these, and two or more of them can be used in combination as needed.

The amount of the leuco dye used is about 5 to 35% by weight, preferably about 5 to 20% by weight, based on the total solid content of the heat-sensitive recording layer in the heat-sensitive recording layer. 3 to 50% by weight based on the total solid content
Degree, preferably about 10 to 40% by weight.

[0040] As coloring agent contained in the color developer thermosensitive recording layer and the thermal transfer receiving layer may include the following compounds.

Acid clay, activated clay, attapulgite,
Acidic clays such as zeolite and bentonite, 4,4 '
-Isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 2,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, bis (3- Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4′-methyldiphenylsulfone, 4-hydroxy-4′-benzyloxydiphenylsulfone, 3,4-dihydroxyphenyl-
4'-methylphenyl sulfone, hydroquinone monobenzyl ether, 4-hydroxybenzophenone, 1,1
-Bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [(4-hydroxyphenyl) isopropylidene] benzene, benzyl 4-hydroxybenzoate, phenolic compounds such as novolak-type phenolic resins and phenolic polymers Compound, 4- [2- (p-methoxyphenoxy) ethyloxy] zinc salicylate, 4- [3-
(P-tolylsulfonyl) propyloxy] zinc salicylate, 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] zinc salicylate, zinc 4-octyloxyacetylaminosalicylate, mono (or bis or tris or tetrakis) [ Zinc of salicylic acid derivatives such as poly (0-4) [ω-hydro [poly (1-7) α-methylbenz] -α-yl] benzyl] zinc salicylate and zinc 3,5-di (α-methylbenzyl) salicylate Salt, N
-P-tolylsulfonyl-N'-phenylurea, 4,
Compounds having a sulfamide bond in the molecule, such as 4'-bis (p-tolylsulfonylaminocarbonylamino) diphenylmethane. Of course, the present invention is not limited to these, and two or more of them can be used as needed.

The amount of the coloring agent used is 10 to 50% by weight based on the total solid content of the heat-sensitive recording layer in the heat-sensitive recording layer.
About 10 to 70% by weight, preferably about 15 to 40% by weight.
%, Preferably about 15 to 50% by weight.

Of these, a zinc salt of the above-mentioned salicylic acid derivative is preferred for the thermal transfer receiving layer because it is particularly excellent in heat-sensitive recording properties and pressure-sensitive recording properties.

Thermofusible Organic Compound The heat fusible organic compound contained in the thermal transfer layer generally has a melting point of about 60 to 150 ° C., preferably 65 to 14 ° C.
Organic compounds at about 0 ° C. can be used. Specific examples of the heat-fusible organic compound contained in the thermal transfer layer of the present invention, diphenoxyethane, naphthyl benzyl ether,
Aromatic compounds such as di-p-methylbenzyl oxalate, diendyl oxalate, m-terphenyl, carnauba wax, montan wax, paraffin wax, microcrystalline wax, polyethylene wax, palmitic acid, stearic acid, and behen Higher aliphatic compounds such as acids, stearic acid amide, ethylenebisstearic acid amide, methyl stearate, and stearic anilide are exemplified. Among them, higher aliphatic compounds are preferable because of their excellent pressure-sensitive recording properties. These can be used alone or in combination of two or more.

The amount of the heat-fusible organic compound used is about 50 to 97% by weight, preferably about 40 to 80% by weight, based on the total solid content of the thermal transfer layer.

Heat- sensitive recording layer The heat-sensitive recording layer generally uses water as a medium, and has an average particle size of 0.1.
A heat-sensitive recording layer coating solution obtained by mixing and stirring a leuco dye, a color former, an adhesive, and, if necessary, auxiliaries such as a sensitizer and a storage stability improver, which is finely dispersed to about 1 to 3 μm, is used. Formed on the front surface of the upper leaf base sheet or the front surface of the middle leaf recording sheet by coating and drying so that the coating amount after drying is about ² to 7 g / m ² , preferably about 3 to 6 g / m ^2. Is done.

The use ratio of the leuco dye to the color former is about 50 to 500 parts by weight, preferably about 100 to 300 parts by weight, based on 100 parts by weight of the leuco dye. It is not limited. The amount of the adhesive used may be about 10 to 35 parts by weight based on 100 parts by weight of the heat-sensitive recording layer.

Examples of the adhesive include methyl cellulose, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose, completely (partially) saponified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, and carboxy-modified polyvinyl alcohol. Water-soluble adhesives such as sulfone-modified polyvinyl alcohol, starch and derivatives thereof, casein, gelatin, alkali salts of styrene / maleic anhydride copolymers, and alkali salts of iso (or diiso) butylene / maleic anhydride copolymers; Alternatively, water-dispersible adhesives such as acrylic latex, urethane latex, and styrene / butadiene latex can be used.

Examples of the auxiliary agent include pigments such as kaolin, calcium carbonate, amorphous silica, titanium oxide, aluminum hydroxide, calcined kaolin, zinc oxide, m-terphenyl, di-p-methylbenzyl oxalate, and sulfur. Acid di-p-chlorobenzyl ester, terephthalic acid dibenzyl ester, 1-hydroxynaphthoic acid phenyl ester, 1,2-di- (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 1-phenoxy-2
Sensitizers such as -naphthoxyethane and p-benzylbiphenyl, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-
Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, N, N'-di-2-naphthyl-p
Phenylenediamine, 2,2′-methylenebis (4,
Preservative improvers such as sodium 6-di-tert-butylphenyl) phosphate, waxes such as carnauba wax, montan wax, paraffin wax, microcrystalline wax and polyethylene wax, and higher fats such as stearic acid amide and ethylenebisstearic acid amide Lubricants such as group amides, zinc stearate, calcium stearate, etc., fluorescent dyes, coloring dyes, surfactants, water-proofing agents and the like can also be added.

When the heat-sensitive recording layer is formed on the front surface of the middle-leaf recording sheet, it is preferable that the recording sensitivity of the heat-sensitive recording layer of the middle-leaf recording sheet is higher than that of the upper-leaf recording sheet. Adjustment of the recording sensitivity of these heat-sensitive recording layers
It can be performed according to a known method. Since the sensitivity is basically determined by the melting points of the leuco dye, the color former or the sensitizer, the recording sensitivity can be adjusted by selecting the type of these components.

The coating solution for the heat-sensitive recording layer is applied by a coating method such as an air knife, a Meyer bar, a pure blade, a rod blade, a reverse roll, a gravure, a slit die, and a curtain.

Thermal Transfer Receiving Layer The thermal transfer receiving layer is formed by mixing and stirring a colorant and an adhesive which are finely dispersed in an average particle diameter of about 0.1 to 3 μm using water or an organic solvent as a medium. The coating amount after drying the coating liquid for the receiving layer on the front surface of the lower leaf base sheet and the front surface of the middle leaf base sheet is about 1 to 7 g / m ² , preferably about ² to 6 g / m ^2. It is formed by coating and drying so that

As the adhesive contained in the thermal transfer receiving layer, an adhesive which can be used for the above-mentioned heat-sensitive recording layer can be used. Further, an auxiliary agent that can be added to the heat-sensitive recording layer may be added to the thermal transfer receiving layer.

The coating liquid for the thermal transfer receiving layer is applied by a coating method such as an air knife, a Meyer bar, a pure blade, a rod blade, a reverse roll, a gravure, a slit die, a curtain and the like.

In the thermal transfer receiving layer of the lower leaf recording sheet,
Further, a leuco dye may be contained.

Thermal Transfer Layer The thermal transfer layer is generally formed by applying 1 to 8 g of a heat transfer layer coating liquid obtained by adding a leuco dye to a melted heat-soluble organic compound on the back surface of the upper leaf base sheet and the back surface of the middle leaf base sheet.
/ M ² , preferably about ² to 6 g / m ² , for example, by applying by a hot melt method.

If necessary, the surface of the thermal transfer layer may be covered with 0.1 to suppress the occurrence of color contamination on the thermal transfer receiving layer or the heat-sensitive recording layer due to friction between the surface of the thermal transfer layer and the surface of the thermal transfer receiving layer or the thermal recording layer. A protective layer of about 0.8 g / m ² may be provided. Such a protective layer is formed, for example, by applying a coating liquid containing an ultraviolet curable compound such as an acrylic monomer or a prepolymer as a main component on the thermal transfer layer, and then irradiating with ultraviolet rays.

Incidentally, a polymerization initiator such as benzoin, benzophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone is added to the coating solution, and the protective layer is contained in the thermal transfer layer. A heat-fusible organic compound, an inorganic pigment, an organic pigment and the like can also be added.

The upper lobe recording sheet, the middle lobe recording sheet and the lower lobe recording sheet are overlaid, for example, as shown in FIGS. In general, it is preferable to fix one piece of the heat-sensitive multiplex copy sheet by gluing or the like so that each recording sheet does not shift during recording and use.

When using the thermal multiple copy sheet of the present invention having the above-mentioned structure, various printers for this type of thermal multiple copy sheet are known and are already commercially available. Thermal recording may be performed.

Typically, by performing thermal recording from the thermal recording layer side of the upper leaf recording sheet of the thermal multiplex copying sheet of the present invention, the thermal energy applied thereto causes the thermal recording layer of the upper leaf recording sheet to be heated. A recording image is formed, and at the same time, a leuco dye is transferred from the thermal transfer layer of the upper leaf recording sheet onto the thermal transfer receiving layer or the thermal recording layer of the middle leaf recording sheet to form a thermosensitive recording image, and a plurality of middle leaf recording sheets are formed. The leuco dye is transferred from the thermal transfer layer of the upper middle leaf recording sheet to the thermal transfer receiving layer or thermal recording layer of the lower middle leaf recording sheet to form a thermal recording image, and at the same time, the leuco dye is transferred from the thermal transfer layer of the middle leaf recording sheet. Is transferred to the thermal transfer receiving layer of the lower leaf recording sheet that is in contact with the middle leaf recording sheet to form a thermal recording image. As a result, a recording image is formed on all the recording sheets of the upper leaf recording sheet, the middle leaf recording sheet, and the lower leaf recording sheet at once.

[0062]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but it should be understood that the present invention is by no means restricted thereto. Unless otherwise specified, parts and% in the examples are parts by weight and% by weight, respectively.

Example 1 (1) Preparation of Solution A 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, sulfone-modified polyvinyl alcohol (degree of sulfonation 5 mol%, degree of polymerization 500, saponification degree 8
A composition consisting of 5 parts of a 10% aqueous solution of 8%) and 25 parts of water was pulverized with a sand mill until the average particle diameter became 0.8 μm to obtain a liquid A.

(2) Preparation of Solution B A 10% aqueous solution of 4-hydroxy-4'-isopropoxydiphenyl sulfone, 10 parts of a sulfone-modified polyvinyl alcohol (degree of sulfonation: 5 mol%, degree of polymerization: 500, degree of saponification: 88%) A composition comprising 5 parts and 25 parts of water was pulverized with a sand mill until the average particle diameter became 1.5 μm to obtain a liquid B.

(3) Preparation of Solution C 10 parts of 1,2-di- (3-methylphenoxy) ethane,
A composition comprising 5 parts of a 10% aqueous solution of sulfone-modified polyvinyl alcohol (degree of sulfonation: 5 mol%, degree of polymerization: 500, degree of saponification: 88%) and 25 parts of water was subjected to sand milling until the average particle diameter became 1.0 μm. It was pulverized to obtain a liquid C.

(4). Preparation of coating liquid (I) for heat-sensitive recording layer 50 parts of liquid A, 100 parts of liquid B, amorphous silica (secondary average particle diameter 2.1 μm, oil absorption 180 ml / 100 g) 15
Parts, acrylic resin (average molecular weight: 8 × 10 ⁶ to 10 × 1
0 ⁶⁾ latex (solid concentration: 50%) 30 parts of paraffin wax (melting point: 30% dispersion (average particle size of 75 ° C.): 1 [mu] m) 5 parts, 30% dispersion 20 parts and water of zinc stearate 30 parts of the mixture was mixed and stirred to obtain a coating solution (I) for a heat-sensitive recording layer.

(5). Preparation of coating solution (II) for heat-sensitive recording layer 40 parts of liquid A, 80 parts of liquid B, 40 parts of liquid C, amorphous silica (secondary average particle diameter 2.1 μm, oil absorption 180 ml / 10
0 g) 25 parts, 100 parts of a 10% aqueous solution of polyvinyl alcohol (99 mol% of saponification, polymerization degree 500), 2 parts of a 20% aqueous solution of glyoxal, and 30 parts of water are mixed and stirred, and the coating solution for the heat-sensitive recording layer ( II) was obtained.

(6). Preparation of Coating Solution (I) for Thermal Transfer Layer 10 parts of 3-piperidino-6-methyl-7-anilinofluoran, 50 parts of montan wax and 20 parts of stearamide were added at 100 to 120 ° C. To obtain a thermal transfer layer coating liquid (I).

(7). Preparation of Coating Liquid (II) for Thermal Transfer Layer 10 parts of 3-piperidino-6-methyl-7-anilinofluoran, 40 parts of behenic acid, 30 parts of montan wax and 20 parts of paraffin wax The mixture was mixed and melted at 100 to 120 ° C. to obtain a coating liquid (II) for a thermal transfer layer.

(8) Preparation of Coating Solution for Thermal Transfer Receiving Layer 65 parts of aluminum hydroxide (average particle diameter 1 μm), 20 parts of zinc oxide (average particle diameter 0.5 μm), 3,5-di (α)
-Methylbenzyl) zinc salicylate and α-methylstyrene / styrene copolymer (melt weight ratio = 80 /
20, 30% aqueous dispersion 25 having an average particle diameter of 2.3 μm)
Part (or bis or tris or tetrakis) [poly (0-4) [ω-hydro [poly (1-7) α-methylbenz] -α-yl] benzyl] 30% water of zinc salt of a mixture of salicylic acid 25 parts of a dispersion, 50 parts of a 10% aqueous solution of a carboxy-modified polyvinyl alcohol, 10 parts of a 20% aqueous solution of a polyamide epichlorohydrin resin as a waterproofing agent,
A composition comprising 40 parts of a styrene-butadiene latex (solid concentration: 50%) having a glass transition point of 2 ° C., 5 parts of a 20% aqueous solution of sodium polyacrylate, and 100 parts of water is mixed and stirred to form a coating liquid for a thermal transfer receiving layer. I got

(9) Preparation of Coating Solution for Undercoat Layer 50 parts of calcined kaolin (average particle diameter 1.8 μm) having an oil absorption of 80 ml / 100 g, hollow particles (average outer diameter 1 μm, average inner diameter 0.7 μm, film material) Polystyrene, solid content concentration 50
%) 100 parts of latex, 10 parts of polyvinyl alcohol
% Aqueous solution, 12 parts of styrene-butadiene latex (solid concentration: 50%) and 100 parts of water were mixed and stirred to obtain a coating liquid for an undercoat layer.

(10). Preparation of upper leaf recording sheet Upper leaf base sheet (glassine paper containing 8% by weight of talc having a basis weight of 36 g / m ² , a tension of 1.0 and an average particle diameter of 5 μm)
On one surface (front surface side) of the above, the coating liquid (I) for heat-sensitive recording was coated and dried so that the coating amount after drying was 4.0 g / m ^2, and then supercalendered to form a heat-sensitive recording layer. Provided,
The other side (back side) was coated with 7.0 g / m ² of the heat transfer layer coating solution (I) heated to 120 to 130 ° C., and then cooled to form a heat transfer layer, thereby obtaining an upper leaf recording sheet. Was. In addition,
The contraction point of the thermal transfer layer was 78 ° C.

(11). Production of middle leaf recording sheet Middle leaf base sheet (glassine paper containing 8% by weight of talc having a basis weight of 36 g / m ² , a tension of 1.0 and an average particle diameter of 5 μm)
On one surface (surface side) of the above, the coating liquid (II) for the heat-sensitive recording layer was applied and dried so that the coated amount after drying was 4.0 g / m ^2, and the heat-sensitive recording layer was provided. The density of the layer is 0.
Super calender treatment is performed to 9 g / cm ^3, and the other side (back side) is coated with 6.9 g / m ² of the heat transfer layer coating liquid (II) heated to 120 to 130 ° C., and then cooled. Then, a thermal transfer layer was formed to obtain a midleaf recording sheet. The shrink point of the thermal transfer layer was 73 ° C.

(12). Preparation of lower leaf recording sheet An undercoat is applied to one surface of a lower leaf base sheet (neutral high-quality paper containing a basis weight of 64 g / m ² , a tension of 0.8, and 5% by weight of calcium carbonate). Super calendering layer coating solution and a thermal transfer-receiving layer coating liquid application amount after drying respectively 9.2 g / m ^2, an undercoat layer are sequentially applied and dried so that 5.1 g / m ² Then, after providing a thermal transfer receiving layer,
A super calender treatment was performed so that the density of the thermal transfer receiving layer became 1.1 g / cm ³ to obtain a lower leaf recording sheet.

(13). Production of heat-sensitive multiplex copy sheet The back side of the upper leaf recording sheet cut into A4 size, the front side of the middle leaf recording sheet, the back side of the middle leaf recording sheet, and the front side of the lower leaf recording sheet Were overlapped so as to be in contact with each other to obtain a thermosensitive multiple copy sheet.

Example 2 In the preparation of the thermal transfer layer coating liquid (II) of Example 1, 20 parts of carnauba wax and 20 parts of stearic acid amide were used.
A thermosensitive multiple copy sheet was obtained in the same manner as in Example 1 except that 10 parts of carnauba wax and 30 parts of stearamide were used instead of parts. The contraction point of the thermal transfer layer of the middle-leaf recording sheet of Example 2 was 63 ° C.

Example 3 In the preparation of the thermal transfer layer coating solution (I) of Example 1, except that 20 parts of stearamide and 20 parts of carnauba wax were used, 40 parts of stearamide were used.
In the same manner as in Example 1, a thermosensitive multiple copy sheet was obtained. The contraction point of the thermal transfer layer of the upper leaf recording sheet of Example 3 was 1
03 ° C.

Example 4 In the preparation of the coating solution (I) for the thermal transfer layer of Example 1, 20 parts of stearic acid amide and 20 parts of carnauba wax were used, and 40 parts of ethylenebisstearic acid amide were used. A heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1 except that the coating liquid for the thermal transfer layer was heated to 140 to 150 ° C. in the preparation of the upper leaf recording sheet. The contraction point of the thermal transfer layer of the upper leaf recording sheet of Example 4 was 132 ° C.
Met.

Example 5 In the production of the middle leaf recording sheet of Example 1, the heat-sensitive recording layer was dried by applying the heat-sensitive recording layer coating liquid (II) so that the coating amount after drying was 4.0 g / m ^2. Is provided, instead of performing a super calender treatment so that the density of the thermal transfer receiving layer becomes 0.9 g / cm ³ , the coating amount after drying the thermal transfer receiving layer coating liquid becomes 4.0 g / m ^2. After coating and drying to form a thermal transfer receiving layer, the density of the thermal transfer receiving layer is set to 1.
A heat-sensitive multiplex copy sheet was obtained in the same manner as in Example 1 except that a super calender treatment was performed so as to give 2 g / cm ³ .

Examples 6 and 7 In the production of the middle-leaf recording sheet of Example 1, the density of the heat-sensitive recording layer was changed to 0 instead of performing the super calender treatment so that the density of the heat-sensitive recording layer became 0.9 g / cm ^3. .8g
/ Cm ³ (Example 6) and 1.0 g / cm ³ (Example 7), except that a super calender treatment was performed to obtain a heat-sensitive multiplex copy sheet.

Examples 8 to 9 In the preparation of the lower leaf recording sheet of Example 1, the density of the thermal transfer receiving layer was changed to 1.2 g / cm ³ instead of the super calendering treatment so that the density of the thermal transfer receiving layer was 1.1 g / cm ^3. cm
³ (Example 8) Example 1 was performed except that a super calender treatment was performed so as to obtain 1.3 g / cm ³ (Example 9).
In the same manner as in the above, a heat-sensitive multiple copy sheet was obtained.

Example 10 A thermosensitive multiple copy sheet was obtained in the same manner as in Example 1 except that the undercoat layer was not provided in the preparation of the lower leaf recording sheet of Example 1.

Example 11 A thermosensitive multiple copy sheet was obtained in the same manner as in Example 1 except that the lower leaf recording sheet was prepared as described below.

(1) Preparation of lower leaf recording sheet One surface of a lower leaf base sheet (neutral high-quality paper containing a basis weight of 35 g / m ² , a tension of 1.0, and 25% by weight of calcium carbonate) is coated with an undercoat. Super calendering layer coating solution and a thermal transfer-receiving layer coating liquid application amount after drying respectively 9.2 g / m ^2, an undercoat layer are sequentially applied and dried so that 5.1 g / m ² Then, and after providing the thermal transfer receiving layer, a super calender treatment was performed so that the density of the thermal transfer receiving layer was 1.1 g / cm ³ to obtain a lower leaf recording sheet.

Example 12 The following protective layer coating liquid was applied on the thermal transfer layer of the upper leaf recording sheet and the middle leaf recording sheet of Example 1 in an amount of 0.4 g / m ² respectively.
Example 1 except that a protective layer cured by irradiation with ultraviolet light was provided after coating with an offset printing machine so that
In the same manner as in the above, a heat-sensitive multiple copy sheet was obtained.

(1) Preparation of Coating Solution for Protective Layer A coating solution for a protective layer was obtained by mixing 10 parts of trimethylolpropane triacrylate and 1 part of benzophenone.

Comparative Example 1 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that the coating liquid for thermal transfer layer (I) was used in place of the coating liquid for thermal transfer layer (II) in the production of the middle leaf recording sheet. A multiple copy sheet was obtained.

Comparative Example 2 A thermal transfer layer coating liquid (II) was used in place of the thermal transfer layer coating liquid used in the preparation of the upper leaf recording sheet of Example 3, and a middle leaf recording sheet of Example 3 was prepared. A heat-sensitive multiple copy sheet was obtained in the same manner as in Example 3, except that the coating liquid for the thermal transfer layer used in the preparation of the upper leaf recording sheet of Example 3 was used instead of the coating liquid for the thermal transfer layer (II).

Comparative Example 3 In the preparation of the upper leaf recording sheet of Example 2, the coating liquid for the thermal transfer layer used for preparing the middle leaf recording sheet of Example 2 was used instead of the coating liquid (I) for the thermal transfer layer, and Example 2 A thermosensitive multiple copy sheet was prepared in the same manner as in Example 2, except that the coating liquid for a thermal transfer layer (I) was used in place of the coating liquid for a thermal transfer layer used in Example 2 in the production of the middle leaf recording sheet. I got

The following evaluation tests were performed on the thus obtained heat-sensitive multiplex copy sheet, and the obtained results are shown in Tables 1 and 2.

[Shrinking Point] The shrinking points of the thermal transfer layers of the upper recording sheet and the lower recording sheet were measured according to JIS K0064.

[Density] The density (g / cm ³ ) of the thermal transfer receiving layer or the heat-sensitive recording layer of the middle leaf recording sheet and the thermal transfer receiving layer of the lower leaf recording sheet are determined by the coating amount (g / m ² ) and the layer thickness (μm). ) And the product.

The thickness (μm) of the layer can be measured, for example, by enlarging the cross section of the recording sheet with an optical microscope or an electron microscope.

[Recording Density] Using a printer [MJ-1, manufactured by Toshiba Tec Corporation], a record is formed on each heat-sensitive multiplex copy sheet, and the recording density of the recording portion of each recording sheet is measured using a Macbeth densitometer [trade name] : RD-914, manufactured by Macbeth Co.] in the visual mode.

[Negation and Blurring of Recording Section] The degree of bleeding and blurring of the recording section of the middle and lower lobe recording sheets in the evaluation of the recording density was visually judged by a loupe (magnification: × 10). (Degree of bleeding): There is almost no bleeding. : There is a little bleeding. '': There is bleeding. ×: Large bleeding. (Degree of blurring) A: There is almost no blurring. : There is slight blurring. '': There is blur. X: The blur is large.

[0096]

[Table 1]

[0097]

[Table 2]

[0098]

As shown in Table 2, the multiple thermographic copying sheets of the present invention are excellent in the recording density of the thermal recording image of each recording sheet and have the effect of reducing blurring and / or blurring. is there.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an arrangement state of an upper leaf recording sheet, a middle leaf recording sheet, and a lower leaf recording sheet of the present invention, which has one middle leaf recording sheet.

FIG. 2 is a schematic diagram showing an example of an arrangement state of an upper leaf recording sheet, a middle leaf recording sheet, and a lower leaf recording sheet of the present invention in which two middle leaf recording sheets are provided.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 upper leaf recording sheet 11 base sheet 12 thermal recording layer 13 thermal transfer layer 20 middle leaf recording sheet 21 substrate sheet 22 thermal transfer receiving layer or thermal recording layer 23 thermal transfer layer 25 middle leaf recording sheet 26 substrate sheet 27 thermal transfer receiving layer or thermal recording Layer 28 Thermal transfer layer 30 Lower leaf recording sheet 31 Base sheet 32 Thermal transfer receiving layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Chieko Oshisaka 4-3-1 Jokoji Temple, Amagasaki City, Hyogo Prefecture Inside Oji Paper Co., Ltd. Amagasaki Research Center (72) Inventor Masanori Ohashi 4-chome Johoji Temple, Amagasaki City, Hyogo Prefecture No. 1 Inside the Oji Paper Co., Ltd. Amagasaki Research Center (72) Inventor Shinichi Matsumoto 6-17-1 Kamitsumuro, Takatsuki City, Osaka Prefecture Inside and outside Carbon Ink Co., Ltd. (72) Inventor Nobuhiko Kitada 6-17, Kamidomuro, Takatsuki City, Osaka Prefecture No. 1 Inside and outside Carbon Ink Co., Ltd. F-term (reference) 2H026 AA07 AA28 BB01 DD42 DD53 FF03 FF27 GG01

Claims (6)

[Claims] 1. A heat-sensitive recording layer containing a leuco dye, a color former and an adhesive on the front surface of a base sheet,
Upper leaf recording sheet having a heat transfer layer containing a leuco dye and a heat-fusible organic compound on the back surface, (b) on the front surface of the base sheet, a heat transfer receiving layer containing a colorant and an adhesive, or ,
Leuco dye, having a heat-sensitive recording layer containing a colorant and an adhesive, at least one middle leaf recording sheet having a thermal transfer layer containing a leuco dye and a heat-fusible organic compound on the back surface, and (c) substrate Including a lower leaf recording sheet having a heat transfer receiving layer containing a colorant and an adhesive on the front surface of the sheet, the upper leaf recording sheet, the at least one middle leaf recording sheet and the lower leaf recording sheet are And the back surface of the upper recording sheet is opposed to the front surface of the lower recording sheet in any two adjacent recording sheets among these recording sheets. , Shrinkage point of thermal transfer layer of upper leaf recording sheet (JIS K
0064), the shrinking point (JI) of the thermal transfer layer of the middle leaf recording sheet in contact with the lower leaf recording sheet
(Based on the melting range measurement method of SK 0064). 2. The shrinking point of the thermal transfer layer of the upper leaf recording sheet,
The heat-sensitive multiplex copying sheet according to claim 1, wherein a difference between the contraction point of the thermal transfer layer of the middle leaf recording sheet and the contraction point of the thermal transfer layer is 5 to 20C. 3. The contraction point of the thermal transfer layer of the upper leaf recording sheet is as follows:
3. The heat-sensitive multiplex copying sheet according to claim 1, wherein the temperature is 65 to 130 [deg.] C. 4. The number of middle leaf recording sheets is one.
4. The heat-sensitive multiplex copy sheet according to any one of items 1 to 3. 5. The contraction point (A) of the thermal transfer layer of the upper leaf recording sheet is two, and the contraction point (A) of the thermal transfer layer of the first middle leaf recording sheet adjacent to the upper leaf recording sheet is 5. B1) or higher than the contraction point (B1), and the contraction point (B1) is higher than the contraction point (B2) of the second middle leaf recording sheet adjacent to the first middle leaf recording sheet. The heat-sensitive multiplex copying sheet according to any one of claims 1 to 3, which is high. 6. The thermal transfer receiving layer or heat-sensitive recording layer of the middle leaf recording sheet and the thermal transfer receiving layer of the lower leaf recording sheet have a density of 0.9 to 1.2 g / cm ^3. A heat-sensitive multiplex copying sheet according to the item.