JPS5821597B2 - Kanatsu Fukushi Palm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coloring agent that exhibits a remarkable coloring effect when used in copying paper, that is, pressure-sensitive copying paper, on which arbitrary writing and printing can be performed without requiring carbon paper.

All pressure-sensitive copying papers, with the exception of special types, utilize a coloring reaction caused by the exchange of electrons between a colorless compound of an electron-donating organic dye and a coloring agent, which is an electron acceptor.

(US Pat. No. 2,548,366) As a colorless compound of an organic dye serving as a coloring reaction substance, two or more types of dyes having different coloring states are usually used in combination.

For example, triphenylmethane/phthalide dyes and fluoran dyes that develop color instantly when they come into contact with a solid acid, and phenothiazine dyes that do not develop color immediately upon contact with a solid acid and may take several days to develop. A material that completely develops color and has high light resistance after color development is used.

In addition, solid acids are generally used as coloring agents which are electron acceptors, such as attapulgite, kaolin, bentonite, silica, alumina, magnesia, natural zeolite, halloysite, dioctahedral type montmorillonite such as acid clay, and activated clay. Natural or acid-treated clays such as acid-treated products are known, and some of them have been put into practical use.

Recently, high-grade phenolic resins such as P-phenylphenol-formaldehyde condensation resin and polyvalent metal salts of aromatic carboxylic acids such as zinc 3-phenylsalicylate have also been put into practical use.

Pressure-sensitive copying paper that uses these colorless dyes and coloring agents is produced by coating the dye dissolved in oil, wrapped in capsules (microcapsules) of gelatin, gum arabic, or synthetic resin with a diameter of several microns. Paper [Transfer paper (Coa)
It consists of two types of paper: ted back or CB paper' and paper coated with a coloring agent (coated front or CF paper).

However, when the two are placed one on top of the other so that the coated surfaces face each other and pressure is applied with a ballpoint pen or typewriter, the capsule in the area where the pressure is applied ruptures and the oil and colorless pigment come into contact with the coloring agent and develop color. A colored mark is placed there.

If you need two or more copies, use an intermediate paper (Coated Front and Back) coated with a coloring agent on the front side and microcapsules containing a pigment on the back side.
It is used by placing one or more sheets of CFB paper between the transfer paper and the receiver paper.

Silicic acid (e.g., silica gel), zinc hydroxide, or zinc silicate (e.g., zinc orthosilicate) colors colorless dyes for pressure-sensitive copying paper (e.g., crystal violet lactone (CVL) based on triphenylmethane phthalide),
It has been known that it is effective as an additive aid.

However, when used alone, these are difficult to put to practical use due to low color development performance or low light resistance of printed characters after color development.

For example, silicic acid (synthetic silica gel, diatomaceous earth, silicic acid gel produced by thorough acid treatment of natural clay, etc.) has a fairly high initial coloring performance for pigments such as CVL, but the light resistance after coloring is poor. Low and easy to fade.

Furthermore, substances such as zinc hydroxide (zinc hydroxide, basic inorganic zinc acids such as basic zinc chloride, and zinc oxide) have the disadvantage that coloring performance itself is extremely low.

In addition, zinc silicate, which is conventionally known as a material for pressure-sensitive copying paper, has an atomic ratio of silicon to zinc of 1=1 or 1:2.
The atomic ratios of zinc metasilicate or zinc orthosilicate, such as those of Zinc Metasilicate or Zinc Orthosilicate, or those close to them, are combined with composite bases (for example, JP-A-48-53811) or additive auxiliaries (
For example, even if it is effective to some extent as Japanese Patent Publication No. 49-13454), the coloring performance is low when used alone, and it cannot be put to practical use at all.

Among these, crystalline zinc silicate (for example, zinc orthosilicate), which has a completely strong chemical bond of silicic acid and zinc, has almost no coloring performance.

The present invention relates to a coloring agent which, unlike any of the above-mentioned solid acids (silicic acid, zinc silicate, zinc hydroxide, etc.), has very excellent coloring performance and good light resistance after coloring.

More specifically, the present invention provides a method in which the atomic ratio of Si to Zn is from 0.02 to 1:0.5, preferably from 1:0.04 to 1.
: Silicic acid gel having a composition of 0.4 or SiO
The present invention relates to a color former consisting of a mixture or at least partially reacted reaction product of an active silicic acid compound with a content of 88% or more by weight and zinc hydroxide or basic inorganic zinc.

For example, the following method is suitable for producing the color former of the present invention.

(1) Silicic acid hydrogel obtained by the reaction of an alkali silicate and an inorganic acid, and zinc hydroxide or basic inorganic acid zinc (e.g. Zn5(OH)3C1□) obtained by the reaction of an inorganic acid zinc and an alkali hydroxide. The atomic ratio of Si to Zn is 1:0.02 to 1:0.5, preferably 1:0.
The mixture is mixed in a ratio of 0.4 to 1:0.4, dried if necessary, and pulverized.

The drying temperature in this case may be lower than the temperature at which silicic acid and zinc form a strong chemical bond (for example, 700°C or higher), but from an industrial standpoint, 100 to 500°C is preferable.

(2) 5i0 obtained by sufficiently acid-treating natural clays
2. A silicic acid compound having a content of 88% by weight or more (e.g. rubber filler reinforcing agent = white carbon) and zinc hydroxide or basic inorganic acid zinc as described above are combined so that the atomic ratio of Si and Zn is 1.
:0.02 to 1:0.5, preferably 1:0.04 to 1:0.4, and dry if necessary.
Smash.

(3) Si and Z
Mix and disperse in water so that the atomic ratio of n is 1:0.02 to 1:0.5, preferably 1:0.04 to 1:0.4, and neutralize by adding alkali hydroxide, Wash, dry, and crush as necessary.

(4) Precipitate obtained by the reaction of alkali silicate and inorganic acid zinc, that is, the atomic ratio of Si and Zn is 1:0.02
1:0.5 to 1:0.5, preferably 1:0.04 to 1:
If necessary, the co-precipitate of zinc hydroxide and silicic acid having a concentration of 0.4 is washed with water, dried, and pulverized.

In this case, it is preferable that the amounts of both alkalis and inorganic acids are adjusted in advance so as to be equivalent to neutralization, and the reaction is carried out by simultaneous addition or unilateral addition.

The above are the main methods for implementing the present invention, but the methods for implementing the present invention are not limited to the above four methods.

In short, in the present invention, silicic acid gel or SiO
□A silicic acid compound having a content of 1% by weight or more and zinc hydroxide or basic inorganic zinc are combined in an atomic ratio of Si to Zn of 〇, 0.
Mix as closely as possible to give a ratio of 2 to 1:0.5, preferably 1:0.04 to 1:0.4, and dry at a temperature below 700°C, preferably in the range of 100 to 500°C, All it has to do is grind it to an appropriate particle size.

In this color former, the component ratio of silicic acid and zinc, which are the main components, is 1:0.02 to 1:0 in terms of the atomic ratio of Si to Zn.
5. It is important that the ratio is preferably 1:0.04 to 1:0.4.

The silicic acid compound referred to in the present invention refers to a compound with an SiO2 content of 88% by weight or more obtained by sufficiently acid-treating natural clays such as activated clay, acid clay, halloysite, kaolinite, and natural zeolite. As mentioned above, silicic acid gel or silicic acid compounds exhibit high coloring performance for colorless dyes such as triphenylmethane phthalide and fluoran-based dyes, which develop color by cleavage of lactone rings. Coloring properties of substances such as zinc are extremely low relative to colorless pigments.

Therefore, as the atomic ratio of Si to Zn in the mixture decreases, that is, as the Zn content increases, the coloring performance of the silicic acid gel or silicic acid compound is diluted, and as a result, the coloring performance of the mixture of these two types decreases. It is most easily estimated that the color performance decreases monotonically.

In other words, it is presumed that adding zinc hydroxide or the like for the purpose of further enhancing the coloring performance of the silicate compound is not only meaningless but also contrary to the purpose.

However, according to the research conducted by the present inventors, surprisingly, in areas where the Zn content is low, the coloring performance increases as the Zn content increases, and when it reaches a certain point, it decreases, and the Zn content increases. As the size increases further, the coloring performance decreases significantly, and the atomic ratio of Si to Zn is 1:0.
．． 5. Particularly preferably when the ratio is 1:0.4 or less, compared to the original silicic acid gel or silicic acid compound containing no Zn,
It was discovered that the density of the colored surface immediately after coloring and after one month had clearly increased.

Thus, using the method described above, the atomic ratio of Si to Zn is between 1:0.02 and 1:0.5, particularly preferably 1.
:0.04 to 1:0.4 by producing a mixture of silicic acid gel or silicic acid compound and zinc hydroxide or basic inorganic acid zinc or a partial reaction product thereof,
A color forming agent for pressure-sensitive copying paper which has excellent initial color development performance and light fastness of color printing has been obtained.

The present invention will be explained in more detail below with reference to Examples.

In addition, the method of crushing, the method of preparing stamp paper, and the method of measuring its color development performance in Examples are as follows.

(1) Grinding The dry cake obtained in each example was crushed using an experimental impact pulverizer (manufactured by Fuji Denki Kogyo KK, Nick Sample Mill Kn).
-1 type) or a porcelain pot mill (capacity 1').
) Medium, 30 minutes with a porcelain pole, then 4 minutes with a Korean pole.
Grind for 5 minutes.

(2) Preparation of stamp paper Take 20 g of the coloring agent sample prepared in each example on a dry weight basis at 110°C, add 50 g of water and SBR.
Latex (Dow6201 solid content concentration 50%) 10g
After dispersing the slurry in water, the pH of the slurry is adjusted to 9.5 by adding 10% NaOH.

Further, a small amount of water is added to bring the total amount to 100 g, and a uniform slurry is obtained by stirring.

(Coloring agent concentration - 20%, solid content concentration - about 25%).

The slurry prepared as described above is applied to four base papers each using a coating rod.

(3) Color development performance (3-1) Color development A transfer paper coated with microcapsules containing various colorless dyes and a stamp paper prepared by the above method are stacked and pressed to develop color.

That is, the two sheets of paper are stacked so that the coloring agent-coated side of the stamp paper and the microcapsule-coated side of the transfer paper face each other.
A pressure of 500 kg/d was applied to completely crush the microcapsules to obtain a colored surface on the stamp paper.

The colorless dyes included in the various transfer papers used are as follows.

(The color tone in parentheses) CvL paper (violet) = crystal violet.
Lactone fluoran paper (green) -37-dinitylamino-7'-dibenzylamino fluoran commercial transfer paper (blue/black) -Crystal violet lactone,
Benzoyl, leucomethylene blue, rhodamine B, anilinolactam.

(3-2) Initial color development performance: Expose the colored surface of the stamp paper obtained by the method in (3-1) indoors to avoid direct sunlight, and measure the reflection density in the visible region after 1 hour using a densitometer ( Manufactured by Fuji Photo Film KK, Fuji
iDensitcmeterModel-P), and determined by the average value of the measured values of 4 samples for each sample and visual observation, and the evaluation is indicated by the following mark.

× mark Coloring density is too low to be practical △ mark Coloring density is low but practical Items/marks with higher color density than the ○ mark Items with extremely high color density (3-3) After leaving the color-receiving stamp paper measured in printing light resistance (3-2) for one month in the same way, the color at that time was determined. The light fastness of the print is evaluated based on the darkness and degree of fading as follows.

△ Mark: Low concentration and poor light resistance ○ Mark: Light resistance sufficient for practical use (2 commercially available coloring agent Jiruton M-AB', manufactured by Mizusawa Kagaku Kogyo KK) ◎ Mark: Better light resistance than ○ Mark: Example 1 No. 1 water glass (0,600mol, Sin□/1
00g, 0.274rnol, Na2O/10
0 g) 1000g dissolved in water to form 21 and hydrochloric acid (reagent grade, 1, OOmol, HCI/100g) 5
Dissolve 48 g in water to obtain 21, and pour the same amount at the same time into a container that has previously been heated to 85°C with water in 61 (pouring rate = 201 nl).
/ minute).

After the addition, stirring was continued for 1 hour, and the suction filtration method was used to thoroughly wash with water to obtain a silicic acid hydrogel cake (0,290
mol, 5in2/100 g).

On the other hand, zinc chloride (reagent grade, 0.660 mol).

Dissolve 400g of ZnCl2/100g) in water to obtain 21 and sodium hydroxide (reagent grade, 2.33mol)
, NaOH/100. p) Dissolve 227 g in water to obtain 21, and simultaneously pour the same amount into a container that has been heated to 80°C and filled with water from 101 while stirring (pouring rate = 20 TrLl/min). ).

After the addition, stirring was continued for 1 hour, and the suction filtration method was used to thoroughly wash with water to remove zinc hydroxide and basic zinc chloride (= Zn5
(oH)3c12) mixture cake (0,72
1mo1. ZnO/100g) is obtained.

The silicic acid hydrogel cake obtained above and the mixture cake of zinc hydroxide and basic zinc chloride were mixed with Si vs. Zn.
The atomic ratio of is 1:0.02 (Example 1-1), 1:0.0
4 (Example 1-2), i: o, o s (Example 1-2)
3), 1:0.2 (Example 1-4) or 1:0.5 (Example 1-5), disperse in water, mix well by stirring, and then apply suction. do.

The obtained filter cake was dried at 110° C. and pulverized using an impact pulverizer (throughput of 200 meshes) to obtain the coloring agent of the present invention.

The coloring performance of this coloring agent is shown in Table 1 along with Comparative Examples 1-1 (atomic ratio 1:O-silicic acid only), 1-2 (atomic ratio 1:1) and 1-3 (atomic ratio 1:2). show.

Note: The numbers in parentheses indicate the visible reflection density.

Example 2 Zinc sulfate (reagent-grade, 0.344mol.Zn5O.

Dissolve 800 g of 21, saliva and potassium hydroxide (reagent grade, 1.52 mol) in water.

KOH/1101) 362 was dissolved in water to form 21, and the same amount was simultaneously poured into a container containing 101 water in advance while stirring at room temperature (pouring speed = 207
rLl/min).

After the addition, stirring was continued for 1 hour, and the paper was thoroughly washed with water using a suction filtration method.

Zinc hydroxide cake (0,680 mol, ZnO/1
00g).

Zinc hydroxide cake obtained as above and acid clay from Nakajo Town, Niigata Prefecture (=dioctahedral type montmorillonite)
A silicic acid compound obtained by sufficiently acid-treating with sulfuric acid (manufactured by Mizusawa Kagaku Kogyo KK, rubber filler reinforcing agent Jiruton A, 1
．． 55mo1. Sin□/100I, i.e. SiO
2 content 93% by weight) with an atomic ratio of Si to Zn of 1:0.0
2 (Example 2-1), 0.04 (Example 2-2), 1
:0.06 (Example 2-3) 1:0.08 (Example 2-
4), 1:0.1 (Example 2-5), 1:0.2 (Example 2-6), 1:0.3 (Example 2-7), 〇, 4 (
Example 2-8) or 1:0.5 (Example 2-9), dispersed in water, mixed well by stirring, and filtered by suction.

The obtained filter cake was dried at 110° C. and pulverized using an impact pulverizer (throughput of 200 meshes) to obtain the coloring agent of the present invention.

The coloring performance of this coloring agent was evaluated in Comparative Examples 2-1 (atomic ratio 1:O = Zilton A only), 2-2 (atomic ratio 1:1) and 2-3 (
They are shown in Table 2 along with the atomic ratio (1:2).

Example 3 A solution prepared by dissolving No. 1 water glass 1001 in water to form 21 and zinc nitrate (reagent grade, 0.319 mol).

Zn(NO3)2/100.9) 190g and nitric acid (reagent grade, 0.968mol, HNO3/100,
! ii') Dissolve 443 g of 21 in water and pour the same amount of 21 and the soybean liquid simultaneously into a container that has been heated to 75°C and filled with water of 117 while stirring vigorously (pouring speed - 201rLlZ). ) to form a coprecipitate of silicic acid and zinc hydroxide (atomic ratio of Si to Zn = 1:0.1,
pH 7.4) is obtained.

After thoroughly washing with water using the suction filter method, the resulting filter cake was dried at 110°C, then calcined at 500°C for 3 hours, and pulverized using an impact pulverizer (throughputting 200 mesh) to produce the present invention. A color former was obtained.

The coloring performance of the present invention was evaluated in Comparative Examples 3-1 (silicic acid obtained from No. 1 water glass and nitric acid by simultaneous addition method) and 3-2 (
A co-precipitate of silicic acid and zinc hydroxide (atomic ratio 1:1) obtained by the reaction of a mixed aqueous solution of No. 1 water glass, sodium hydroxide, and an aqueous solution of zinc nitrate (atomic ratio 1:1) as well as No. 3
Shown in the table.

Claims (1)

[Claims] 1 A mixture of silicic acid gel or a silicic acid compound having a S i O,2 content of 88% by weight or more obtained by sufficiently acid-treating natural clays and zinc hydroxide or basic inorganic acid zinc, or at least partially and the atomic ratio of Si to Zn is 1:0.02 to 1:0.5.
A coloring agent for pressure-sensitive copying paper, characterized by having the following composition: