JPS62187077A - Coupler composition for leuco dye - Google Patents

Abstract

PURPOSE:To facilitate coating work by lowering the viscosity of a coating solution, by mixing an inorg. solid acid coupler having laminar silicic acid as a skeletal, thiourea or an isomer thereof and carbonate of a metal belonging to the Groups II, III, IV of the Periodic Table. CONSTITUTION:An inorg. solid acid coupler having laminar silicic acid as a skeletal, thiourea or an isomer thereof and carbonate of a metal belonging to the Groups II, III, IV, VII, VIII of the Periodic Table are premixed by a dry or wet method to prepare a coupler composition for a leuco dye. As the coupler having laminar silicic acid as the skeletal, there are one having only laminar silicic acid as a fundamental skeletal and one having such a fundamental structure that laminar silicic acid and a basic metal oxide layer form a two-layered or three-layered structure. 1-100wt% of thiourea and 1-100wt% of carbonate are pref. used on the basis of the inorg. solid acid coupler.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application to which the Invention Pertains) The present invention relates to a developer composition for leuco dyes and a friendly pressure-sensitive recording element using the same. This invention relates to a color developer composition having a combination of excellent initial color development, fade resistance, and water resistance.

(Prior Art) Conventionally, a combination of a leuco dye and a color developer made of an acidic VIJ substance has been widely used for various information recording purposes, such as pressure-sensitive recording, heat-sensitive recording, electrophotographic recording, printing, etc. There is.

Color developers include organic ones such as various phenols, phenolic resins, zinc salicylate and its derivatives, and those made of inorganic solid acids such as silica, aluminum silicate, clay minerals or their acid-treated products. Although it is known that inorganic solid acid-based materials have excellent heat resistance, solvent resistance, printing and transcription properties, etc., they have poor coloring performance and fading due to the effects of light, heat, and moisture. Defects are observed on the surface.

For example, a color developer made of amorphous silica gives a clear colored image when combined with a leuco dye, but the image formed has extremely poor light resistance; Image density decreases to 50% or less.

Furthermore, although aluminosilicate-based clay minerals or acid-treated products thereof have slightly better light resistance than amorphous silica, they tend to cause discoloration when images come into contact with water.

In particular, in the field of pressure-sensitive paper, a paper substrate with a layer of color developer on one side is used as a so-called stamp paper, but when used as a coloring agent for clay minerals and their acid-treated mtS. However, there is a problem in that the coating layer is colored in a unique hue.

Further, known color developers tend to change color when exposed to light or the environment for a long time, and this tendency is remarkable in the case of organic color developers such as phenolic resins.

JP-A-56-37189 discloses that a combination of a thiourea compound and zinc oxide and/or zinc hydroxide is added to a solid #1 color developer such as acid clay or activated clay as a color development enhancer and anti-fading agent. It is stated that

(Problems to be Solved by the Invention) First, inorganic solid acid color developers, like other inorganic color developers, have an extremely high viscosity when used as an aqueous coating solution. This creates a constraint that the agent must be applied to the paper as a coating liquid at a relatively dilute concentration. On the other hand, in terms of pressure-sensitive paper manufacturing costs, it is desirable to reduce the thermal energy cost for evaporating water as much as possible, so the viscosity of the color developer coating solution is lowered and the solid content concentration is reduced as much as possible. It is an important technical requirement to improve the efficiency of the technology.

In particular, when a metal oxide or hydroxide is added to this inorganic solid acid color developer as seen in the prior art,
The disadvantage is that the viscosity of the coating solution is much greater than that of the inorganic solid acid color developer alone.

(Means for Solving the Problems) The present inventors added a thiourea compound or its isomer and groups Ⅰ and ① of the periodic table to an inorganic solid acid developer having a skeleton of layered silicic acid. Group, Group 1, Group IV.

When a Group VII or Group II metal carbonate is mixed and at least a portion of them is reacted, the viscosity of the coating solution is lowered compared to a coating solution containing only an inorganic solid acid color developer. It has been found that the process workability can be significantly improved.

In addition, the present inventors have discovered that in this color developer composition,
It has been found that initial color density, fade resistance and water resistance are improved in combination.

(Function) In the present invention, the remarkable reduction in the viscosity of the coating liquid and the improvement in the initial color density, fading resistance, and water resistance can be achieved by blending thiourea or its isomer and carbonate with the inorganic solid acid developer.
This is possible only through partial reaction.

That is, as shown in the example below, when thiourea alone is blended with the inorganic solid acid color developer or when carbonate alone is blended, the viscosity of the aqueous coating solution is compared to that of the coating solution containing the color developer alone. It cannot be lowered compared to that of the basolateral. In addition, when oxides and hydroxides are used in place of the carbonate in the above-mentioned surplus, even in combination with thiourea, the viscosity increases significantly compared to the viscosity of the coating solution using only the color developer. Is recognized.

On the other hand, in the present invention, group Ⅰ of the periodic table,
From the above-mentioned facts, it is completely clear that if a compound of Group Ⅰ, Group 0, Group IV, or Group Unexpectedly, it has been found that the viscosity of the aqueous coating solution is significantly lower than that of the developer alone. Although the reason for this has not yet been elucidated, it is thought that the cause is a reaction between the inorganic solid acid color developer, the thioureas, and the carbonate.

In addition, in the composition of the present invention, it is confirmed from the following fact that a reaction occurs between the above three components. First, when performing X-ray diffraction on the composition obtained by mixing the three components, applying the mixture in liquid form, and drying, the diffraction peaks unique to thiourea and carbonate, respectively, almost disappear. . Next, when we look at the diffraction peaks specific to the inorganic solid acid developer in this composition, we find that the interplanar spacing of the plane index (001) plane, that is, the interval between the basic unit layers, is that of the original inorganic solid acid developer. It increases significantly compared to that. Further, some of the metal components in the carbonate are ionized and solubilized. From the above facts, when thiourea and carbonate are mixed with an inorganic solid acid color developer, a reaction occurs between them, and the metal components in thiourea and carbonate are incorporated between the layers in the color developer. , it becomes clear that it is incorporated.

Furthermore, the metal components of Groups 1, 2, 1, 4, or 2 of the periodic table incorporated between the layers are compared to compositions that simply contain these components in a mixed state. Therefore, it acts to significantly improve the initial color density, fading resistance and water resistance of the inorganic solid acid color developer, and this fact will become clear from the examples described below.

(Advantageous Effects of the Invention) According to the present invention, it is possible to greatly reduce the viscosity of the coating liquid of the color developer. Workability can be significantly improved, and the solid content concentration in the coating liquid can be increased to reduce the cost of thermal energy required for evaporating water.

In addition, it increases the initial color density of the image formed by the reaction between the inorganic solid acid color developer and the leuco dye, prevents the tendency of fading due to exposure to light and various atmospheres, and further improves the compatibility with water. It is possible to prevent the tendency of the image g# density to decrease significantly due to contact.

(Description of Preferred Embodiments of the Invention) In the present invention, as the inorganic solid acid color developer, one having a skeleton of layered silicic acid is used. The term "layered silicic acid as a skeleton" refers to inorganic layered compounds in which the basic skeleton consists of only layered silicic acid, as well as two or three layers of layered silicic acid and a basic metal oxide layer. is included. Suitable examples of the former include layered activated silica obtained by thoroughly acid-treating smectite clay minerals such as acid clay and bentonite, and layered activated silica with CaO+
These include layered silicic acid obtained by reacting basic oxides or hydroxides such as MgO and ZnO-Aj203.

Suitable examples of the latter include clay minerals that exhibit properties as solid acids, clay minerals that have been acid-treated to have the basic layered structure of clay minerals, or synthetic clay minerals. These minerals have a three-layer structure in which two 5in4 tetrahedrons are sandwiched with an octahedral layer of AlO2 and/or MgO6 in between, and this basic layer unit is C.
The basic unit is a two-layer structure in which an octahedral layer of Al2O3/SiO06 and/or MgO6 and a tetrahedral layer of 5io4 are integrated in the axial direction, and this basic layer unit is integrated in the C-axis direction. Examples include things. In these minerals, the degree of accumulation in the C-axis direction varies from those with a regular degree of accumulation like natural or synthetic clay minerals to those with a random degree of accumulation like acid-treated clay minerals. It can change.

One example of a color developer suitable for the purposes of the present invention is AA20〆S
The molar ratio of iO2 is 0.6 to 0.01. In particular, it is within the range of 0.4 to 0.01 and the specific surface area is 180 m2/
acid-treated montmorillonite minerals in the range of 200 m2/g or more, especially 200 m2/g or more; another good example is MgO/
The molar ratio of 5102 is 0.14 to 1.20. Especially 0.2
8 to 0.97 and the specific surface area is 180 m/
It is a magnesium salt of layered silicic acid in a range of at least 200 m/g, particularly at least 200 m/, j9.

It is known that thiourea isomerizes to ammonium rhodanate. Although it is desirable to use thiourea in the present invention, ammonium rhodanate can also be used, or a mixture of both can be used.

Carbonates include metals from Group 1 of the periodic table, such as calcium, magnesium, barium, strontium, zinc, cadmium; metals from Group 2, such as aluminum; metals from Group I, such as aluminum;
Carbonates of Group V metals, such as tin and lead; Group I metals, such as iron, cobalt and nickel, are used. As carbonate,
It may be a normal carbonate or a basic carbonate. Particularly suitable carbonates for the purposes of the present invention are carbonates of metals of Group I of the Periodic Table, especially calcium carbonate and magnesium carbonate.

In the present invention, an inorganic solid acid developer, thiourea, etc. is added in an amount of 1 to 100 tqIb, especially 5 to 50 tqIb, and a carbonate is added in an amount of 1 to 100"it, especially 2 to 100" It is desirable to use an amount of 50% by weight in order to achieve the above-mentioned effect.

These components may be mixed in advance in a wet or dry manner and used to prepare the coating solution, or each component may be added to the coating solution and mixed and reacted on the spot. Good too.

Heating is preferably performed to accelerate the reaction, and this heating may be performed during drying of the coating liquid.

The leuco dye developer composition of the present invention is particularly useful for producing receiving paper for pressure-sensitive recording. When manufacturing receiving paper, add 5 to 50 solid acid developer to the size and 15 to 40 for the size.
An aqueous slurry containing 1 to 10 tqb of a color developer and a binder of 1 to 10 tqb, particularly 3 to 8 tqb, and a color developer of 1 to 10 g/m2, especially 3 to 89 g/m2, is prepared. Apply the desired amount and dry. As the binder, water-based latex binders such as styrene-butadiene copolymer latex; self-emulsifying binders such as self-emulsifying acrylic resin; water-soluble binders such as carboxymethyl cellulose, polyvinyl alcohol, It can be applied to all recording methods that use cyano, and can be widely applied to, for example, thermal recording, electrophotographic recording, printing, etc.

Furthermore, the color developer composition for leuco dyes of the present invention can be mixed with known organic color developers such as phenolic resins, zinc salicylate, or derivatives thereof in various proportions.
This is one of the useful forms of use that takes advantage of the excellent advantages of the developer for leuco dyes of the present invention.

The invention is illustrated by the following example.

The method for preparing the receiving paper and the method for measuring its color development performance in the Examples are as follows.

1. Preparation of receiver paper Take the color developer sample prepared in each example to a weight of 20 g based on dry weight at 110°C, add 50 g of water and SBR.
Latex (Dow620, solid content concentration 50%) 10
After dispersing the sample into 9.5 g, the voice of the cis slurry is adjusted to 9.5 by adding 1096 NaOH. Further, a small amount of water is added to bring the total amount to 100 I, and a uniform slurry is obtained by stirring. (Color former concentration = 20%, solid content concentration = approximately 25%).

The slurry prepared as described above is applied to four sheets of base paper each using a coating/depositing device.

2. Color development performance (2-1) Color development A transfer paper coated with microcapsules containing various colorless dyes and a receiver paper prepared by the above method are placed one on top of the other and pressure is applied to develop color. That is, the two sheets of paper were stacked so that the coloring agent-coated side of the receiving paper and the microcapsule-coated side of the transfer paper faced each other, and a pressure of 500 kp/cm was applied to completely crush the microcapsules and place them on the receiving paper. Obtain a colored surface.

The colorless dyes included in the various transfer papers used are as follows. (The color in parentheses is p4) CVL paper (
Violet) = Crystal Violet Lactone.

Commercially available transfer paper (f-roo black) = crystal violet lactone, benzoyl leucomethylene blue.

(2-2) Initial color development performance The color development surface of the receiver paper obtained using the method in (2-1) was exposed indoors to avoid direct sunlight, and the reflection density in the visible area was measured with a densitometer after 1 hour. (Manufactured by Fuji Yoma Film ■, Fuji
Denaitometsr Mod@1-P), and judgment was made based on the average value of the measured values of four samples for each sample and visual observation, and the evaluation is indicated by the following mark.

× Mark: Color density is low and cannot be put to practical use Δ Mark: Color density is low but practical. ○ Mark: Color density is sufficient for practical use (2 commercially available color developer Jilton DR-1, manufactured by Mizusawa Chemical Industry Co., Ltd.) ◎ mark Items with high coloring density (marked with ○) Items with extremely high coloring density (2-3) Printing light resistance (2-3-1) Indoor light resistance (2-2) Color receiving stamp paper measured in the same way After being left indoors for one month, the light fastness of the print was evaluated as follows based on the color depth and degree of fading.

Marked with Δ: Low concentration and poor light resistance Marked 0: Light resistance that is sufficient for practical use Cz Commercially available color developer Jilton DR-1, Mizusawa Chemical Industry C1e
Made by A)) ◎ mark Better light resistance than ○ mark (2-3-2) Colored stamp paper measured by sunlight resistance (2-2) was left outdoors in direct sunlight for 5 hours on a sunny day. After that (2-3-1)
Perform the same evaluation.

Ability M Example 1 Dissolve thio logs in a specified amount of water (finally 11 with a total solid content of 25%), and while stirring thoroughly, add calcium carbonate and magnesium carbonate in the proportions shown in Table 1. In addition, finally, a commercially available clay-based color developer for pressure-sensitive paper, Jiruton D.
R-1 (manufactured by Mizusawa Chemical Industry (Ie4)) at 110℃ff1
It was treated at 90° C. for 2 hours under a standard temperature of 9a. Thereafter, the entire slurry was sufficiently dried in an electric temperature dryer at 110° C. and ground to obtain a sample. Table 1 shows the properties and performance of these samples. From Table 1, it can be seen that the viscosity decreases and the coloring ability improves even when the solid color developer is used alone.

The proboscis measurement method in Example 1 is as follows.

1. Take 801 on a viscosity powder sample at 110℃ on a dry weight basis, and add 1
00I gradually with stirring, add 30% sodium hydroxide solution to make the powder sample 10, and finally the powder sample concentration is 4.
Add pure water to make it 2 inches and rotate at 100 Orp, p.
After stirring for 30 minutes with m, this sura! J-f:B
Measured using an L-type viscometer.

2. A sample pretreated at 110°C was measured at room temperature using an XM151 diffraction X@ diffraction measurement device. CuKm' as an X-ray source
1 at a scanning speed of 1 degree per minute.

The plane spacing is (peak of 001'1 plane (a-xx, xX
Calculated from 20=8 deviations.

3. In a desiccator filled with water-resistant saturated saline (relative humidity: 75 degrees)
A piece of coated paper is placed in a container, and after being left at 80°C for 24 hours, the coated paper is blown out and the color is developed. This color development rate was compared with the initial color development rate of normal color development.

Example 2 The same procedure as in Example 1 was carried out except that a commercially available half-formed pressure-sensitive paper color developer Zilton 5S-1 (manufactured by Mizusawa Chemical Industry Co., Ltd.), which is layered magnesium silicate, was used. Table these results.
Shown in 2. However, when manufacturing stamp paper.

No adjustment is made by adding NaOH.

As shown in Table 2, it can be seen that the viscosity of the product of the present invention is significantly lower than that of the semi-synthetic solid acid developer alone. Furthermore, it was also observed that the single color development ability was significantly increased.

Example 3 A case will be described in which a commercially available clay-based color developer for pressure-sensitive paper, Jilton DR-1 (manufactured by Mizusawa Chemical Industry Co., Ltd.) is used, and thiourea and calcium carbonate are mixed at the time of preparing a coating solution for stamp paper.

Take Jiruton DR-1 to 20g based on drying at 110℃, add 50g of water and 2.41g of thiourea! and calcium carbonate 1.6.9 (or magnesium carbonate 1.
4g) and further SBR Latex x (Dov620,
After dispersing in 10g (solid content concentration 50%), 10%
By adding NaOH, the - of the υ slurry is reduced to 9.5 ~
Adjust to 11.0. Further, a small amount of water is added to bring the total volume to 100!9, and a homogeneous slurry is obtained by stirring.

Table 3 shows the color development performance of stamp papers coated with these.

Example 4 Each thiourea compound was prepared in the same manner as in Example 1.

The case where various carbonates are used will be described.

Thiourea compounds include thiourea, N-alkylthiourea, and N-arylthiourea; carbonates include basic magnesium carbonate, zinc carbonate, and lead carbonate.

Manganese carbonate and cobalt carbonate The results are shown in Table 4.

Claims (6)

[Claims] (1) Inorganic solid acid color developer with a layered silicic acid skeleton, thiourea or its isomer, and Groups II and III of the synchronization table,
A color developer composition for leuco dyes comprising a reaction mixture of carbonates of Group IV, Group VII or Group VIII metals. (2) A patent claim obtained by mixing 1 to 100% by weight of thiourea or its isomer and 1 to 100% by weight of carbonate per inorganic solid acid developer, and reacting at least a part of them. The composition according to item 1. (3) Inorganic solid acid color developer is Al_2O_3/SiO_2
The composition according to claim 1, which is an acid-treated montmorillonite mineral having a molar ratio of 0.6 to 0.01 and a comparative area of 180 m^2/g or more. (4) The inorganic solid acid developer has a molar ratio of MgO/SiO_2 in the range of 0.14 to 1.20 and a specific surface area of 18
The composition according to claim 1, which is a magnesium salt of layered silicic acid having a molecular weight of 0 m^2/g or more. (5) The composition according to claim 1, wherein the carbonate is calcium carbonate and/or magnesium carbonate. (6) Inorganic solid acid color developer having a layered silicic acid skeleton, thiourea or its isomer, and Groups II and III of the periodic table,
Pressure-sensitive recording element comprising a layer of a composition consisting of a carbonate of a Group IV or Group VIII metal.