JPS646038B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a recording material, and particularly to a recording material using a sulfonyl diphenol compound. 2. Description of the Related Art Conventionally, a color former, a compound that develops a color upon contact with the color former (hereinafter referred to as a color developer), and a recording material that utilizes the coloring reaction are well known. For example, there are pressure-sensitive copying paper, heat-sensitive recording paper, and electrically conductive recording paper.
No. 2730457, No. 3418250, No. 3432327, No. 3981821,
It is detailed in No. 3993831, No. 3996156, No. 3996405, No. 4000087, etc. In these recording materials, clay minerals such as acid clay, bentonite, and kaolin are used as color developers.
Phenol-formalin novolacs, metal-treated novolacs, di-tert-butylsalicylic acid zinc salts, and the like are disclosed. In addition, color formers include compounds that are generally colorless and have partial skeletons such as lactones, lactams, sultones, spiropyrans, esters, and amides, and these partial skeletons ring-open or cleave when contacted with a color developer. has been used. Specifically, crystal violet lactone, benzoylleucomethylene blue, malachite green lactone, rhodamine B lactam, 1,3,3-trimethyl-6'-
Examples include ethyl-8'-butoxyindolinobenzospiropyran. Two or more of these color formers may be used in combination depending on the purpose. By the way, when using the above-mentioned color developer,
When a color developer sheet is left in the air, its color developer ability decreases over time. Since such a decrease in color developing ability has a significant effect on commercial value, improvements are desired. Yellowing of the developer surface over time or due to exposure to sunlight or ultraviolet rays is another drawback that is desired to be improved. Furthermore, the image on the color developer layer disappears due to the influence of organic solvent vapor, plasticizer, etc. This is also an unfavorable phenomenon for recording materials, and is one of the drawbacks that is desired to be improved. Further, if the color forming agent layer and the color developer layer are in contact with each other and get wet with water, the image on the color developer surface becomes unreadable. This is also one of the drawbacks that is desired to be improved. Therefore, the purpose of the present invention is, first, to prevent the deterioration of color developing ability over time, second, to improve solvent resistance, and third, to reduce yellowing of the color developing surface. Fourthly, it provides a recording material with improved water resistance. The above object of the present invention is to treat a sulfonyl diphenol compound as a color developer under special conditions,
This was achieved by using That is, this was achieved by using, as a recording material, a composition prepared by treating a sulfonyl diphenol compound in the presence of an inorganic pigment with a dispersion machine using a media so that the pH of the dispersion becomes 7 to 9. The sulfonyl diphenol compound as used in the present invention is hydroxyphenyl sulfonyl phenol represented by the following general formula () and derivatives thereof. In the above formula, R ₁ and R ₂ represent a hydrogen atom or an alkyl group having 4 or less carbon atoms, and R ₁ and R ₂ may be the same or different. Among these sulfonyl diphenol compounds,
4,4'-sulfonyldiphenol [i.e. 4-
(4-hydroxyphenylsulfonyl)phenol] and 2,4'-sulfonyldiphenol [i.e., 4-(2-hydroxyphenylsulfonyl)phenol] are preferred. Inorganic pigments used in the present invention include natural and synthetic inorganic pigments, specific examples of which include:
barium sulfate, barium carbonate, calcium carbonate,
Aluminum hydroxide, precipitated calcium carbonate, gypsum, asbestos, clay, silica, finely divided silicic acid,
Diatomaceous earth, talc, basic magnesium carbonate, alumina white, gloss white, satin white, zinc white, lead white, basic sulfate, sulfate, lithopone, zinc sulfide, titanium oxide, ammonium oxide, barite, mica, loess, silicic acid Examples include calcium, synthetic calcium carbonate, and magnesium carbonate. Among these inorganic pigments, preferred are those in which basic pigments such as aluminum hydroxide and calcium carbonate are used in combination with clays such as acid clay and activated clay. These are used in an amount of about 5 to 500 parts, preferably about 20 to 100 parts, per 10 parts of the sulfonyl diphenol compound. In order to produce the color developer composition of the present invention, it is necessary to treat the sulfonyl diphenol compound with a disperser in the presence of the above-mentioned inorganic pigment. Having inorganic pigments coexist prevents agglomeration,
This is advantageous in terms of improved color developing ability. Dispersing machines include those that use media and those that do not, but the object of the present invention is achieved by processing with a dispersing machine that uses media. Examples of the dispersing machine using the media used in the present invention include various types such as a sand mill, a dyno mill, an attritor, and a ball mill. Among dispersion machines that use media, those that use high-speed rotation to disperse and can perform continuous processing, such as sand mills and dyno mills, have the advantage of being able to process the mixture continuously and feed it directly into the tank of the coating machine. Most advantageous for the purposes of the invention. Various media are used during dispersion, but usually flint stones, Otsutawa sand, steel balls, ceramics, high alumina balls, zircon, glass beads, etc. are used. Among these materials, spherical ones are superior in handling and maintainability. In addition, it is desirable to perform the treatment with a dispersion machine at a temperature of 30°C or lower in order to prevent the product from sticking. When treated with a disperser, further oxides of metals selected from the group of zinc, aluminum, calcium, magnesium, titanium, nickel, cobalt, manganese, iron, tin, copper, vanadium and chromium,
When a metal compound such as a hydroxide, a silicate, or a carbonate is used in combination, more desirable effects such as a reduction in the viscosity of the coating liquid and an improvement in the color developing ability can be obtained. In this case, a combination of zinc and aluminum compounds is particularly desirable. The desirable combined amount is 1 to 1000 parts per 100 parts of inorganic pigment.
parts, more preferably 10 to 100 parts. The treatment is preferably wet dispersion in the presence of water, and the solid content concentration during the dispersion treatment is 10 to 70%, preferably 30 to 60%. Also, the particle size after treatment is
It is preferably 10μ or less, especially 6μ or less. In the present invention, the pH of the dispersion liquid is one of the important factors that determines the performance of the color developer sheet. When the pH of the dispersion liquid is lower than 7, the color developing ability is low and the color developing ability deteriorates significantly over time. If the pH of the dispersion is higher than 9, the solvent resistance will be poor. The object of the present invention is achieved by adjusting the pH of the dispersion to 7-9. A more preferable range of the dispersion pH is 7.5 to 8.5. The pH of the dispersion liquid is adjusted by the amount of caustic soda used. The binder used in the present invention is selected from the viewpoints of adhesion between the recording layer and the support, surface strength of the recording layer, and the like. Examples of water-soluble binders include proteins (e.g., gelatin, albumin, casein, etc.), cellulose (e.g., carboxymethyl cellulose, hydroxyethyl cellulose, etc.), and sutucarose (e.g., agar, sodium alginate, carboxymethyl starch, gum arabic, etc.). Natural polymer compounds: Water-soluble synthetic polymer compounds such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, styrene-butadiene-methacrylic acid latex, acrylonitrile-butadiene-acrylic acid latex, styrene-maleic anhydride copolymer, etc. and other latexes are used. Among these, carboxy-modified latex is particularly preferred. The recording sheet of the present invention is obtained by applying a coating liquid onto a support such as paper, synthetic paper, film, etc. and drying it. As for the coating method, a method used by those skilled in the art is used, such as an air knife coater, a roll coater, a plate coater, a size press coater, a curtain coat, etc., and it is possible to coat one layer or multiple layers at the same time. . The amount of coating varies depending on the type of sulfonyl diphenol compound used, but 0.2 g/m ² or more is required as the sulfonyl diphenol compound, and approximately 0.2~
^{Approximately} 4.0g/m2 is preferable, more preferably 0.3
^{Approximately} 1.2g/m2 is applied. If the amount is less than 0.15 g, color developing ability cannot be obtained, and the upper limit is determined primarily for economic reasons rather than performance. The color former that reacts with the color developer used in the recording sheet of the present invention is not particularly limited, but specific examples of these color formers include triarylmethane compounds, diphenylmethane compounds, xanthene compounds, and thiazine. Examples include spiro-based compounds, spiro-based compounds, and mixtures thereof. The effect of the present invention is greatest when using triarylmethane, especially crystal violet lactone, which is determined depending on the intended use and desired properties. The color former is dissolved in a solvent and encapsulated, or dispersed in a binder solution and applied to the support. As a solvent, natural or synthetic oils can be used alone or in combination. Examples of solvents include cottonseed oil, kerosene, paraffin, naphthenic oil, alkylated biphenyl, alkylated terphenyl, alkylated naphthalene, diarylethane, triarylmethane, chlorinated paraffin, and the like. U.S. patent for method of manufacturing capsules
A method using coacervation of a hydrophilic colloid sol described in No. 2800457 and No. 2800458,
Examples include the interfacial polymerization method described in British Patent No. 867797 and British Patent No. 991076. The effects obtained by the present invention are listed below. First, deterioration in color developing ability over time is prevented. Second, solvent resistance is improved. Third, yellowing on the developing surface is reduced. Fourth, water resistance is improved. The effects of the recording material of the present invention were confirmed using the following color former sheet. Microcapsules containing color formers are produced, for example, according to US Pat. No. 2,800,457, and specific examples thereof are shown below. All "parts" below refer to "parts by weight." 10 parts of acid-treated pork skin gelatin and 10 parts of gum arabic are dissolved in 400 parts of water at 40°C, 0.2 parts of funnel oil is added as an emulsifier, and 40 parts of color former oil is emulsified and dispersed therein. The color former oil was prepared by dissolving 4% crystal violet lactone in diisopropylnaphthalene. When the size of the oil particles reaches an average of 5 microns, stop emulsification, add water at 40℃, and mix the entire mixture.
Reduce to 900 parts and continue stirring. Next, 10 wt% acetic acid is added to adjust the pH of the solution to 4.4 to 4.6 to cause coacervation. Continue stirring for 20
After a minute has elapsed, cool with ice water to gel the coacervate film deposited around the oil droplets. When the liquid temperature reaches 20℃, add 37wt% formalin 7
Add parts. At 10°C, adjust the pH to 9 by adding a 15wt% caustic soda aqueous solution. Next, heat for 20 minutes while stirring to bring the liquid temperature to 50°C. The microcapsule dispersion thus obtained was
6 as a solid content on 40g/ ^m2 paper after cooling to ℃
It was coated and dried to a coating weight of g/m ² . In the manner described above, a microcapsule sheet containing crystal violet lactone as a coloring agent was obtained. Example 100 parts of activated clay, 20 parts of calcium carbonate, 4.
10 parts of 4′-sulfonyldiphenol, 10 parts of zinc oxide
2 parts of 50 wt% caustic soda solution were dispersed in 200 parts of water using a Keddy mill. This dispersion was processed with a sand mill (32G type manufactured by Igarashi Kikai) at a discharge rate of 300/hr.
A dispersion liquid with a volume average particle size of 3.6μ was obtained. The pH of the dispersion is
It was 8.0. Add 10% PVA (PVA
-117) 50 parts of aqueous solution and 20 parts of carboxy-modified SBR latex (solid content concentration 48%) were added. The mixture was stirred and mixed uniformly, and water was added to adjust the solid content concentration to 20%. This coating liquid was applied to a base paper of 40 g/m ² to a solid content of 6.0 g/m ² using an air knife coater and dried to obtain a recording sheet. Comparative Example 1 A dispersion was obtained in the same manner as in the example except that caustic soda was not used in the example. of dispersion
The pH was 6.5. Then, the same binder as in the example was added and coated in the same manner to obtain a recording sheet. Comparative Example 2 In the example, a 50wt% caustic soda aqueous solution was
A dispersion liquid was obtained in the same manner as in Example except that the amount was changed to 10 parts. The pH of the dispersion was 9.5. Then, the same binder as in the example was added and coated in the same manner to obtain a recording sheet. Comparative Test A comparative test of the recording sheets obtained in Examples and Comparative Examples was conducted as follows. The microcapsule sheet containing the aforementioned crystal violet lactone was used. (i) Color development ability The color density (610 nm,
Measurements were made using a Toshiba Beckman DB spectrophotometer). (ii) Changes in color developing ability over time The recording sheets obtained in Examples and Comparative Examples were
After displaying it in a room at 600 lux for 7 days, the color density was measured one day after pressure printing with a typewriter in the same manner as in (i). (iii) Solvent resistance The resistance of the colored body in (i) to machine oil was visually determined. (iv) Yellowing The recording sheets obtained in the Examples and Comparative Examples were
The sample was exposed to sunlight for 2 hours, and the yellow coloring on the developer surface was visually determined. (v) Water resistance When the colored body of (i) was wetted with water, the degree of decolorization was visually determined. The results of the comparative test are shown in Table 1 below.

[Table] It can be seen from Table 1 above that the recording sheet of the present invention has higher color developing ability, less change over time in color developing ability, and is superior in fastness than the comparative recording sheet.

Claims (1)

[Scope of Claims] 1. A dispersion containing a sulfonyl diphenol compound represented by the following general formula (), which is treated in the coexistence of an inorganic pigment with a dispersion machine using a media so that the pH of the dispersion becomes 7 to 9. A recording material characterized by being coated on a support. In the above formula, R ₁ and R ₂ represent a hydrogen atom or an alkyl group having 4 or less carbon atoms.