JP2836074B2 - 4-Hydroxy-4 ▲ '-isopropoxydiphenylsulfone color developing composition, wet grinding method and dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a 4-hydroxy-4'-isopropoxydiphenyl which is a developer used for recording paper such as thermosensitive recording paper and pressure-sensitive copying paper. For sulfone.

[Conventional technology]

Recording papers such as heat-sensitive recording paper and pressure-sensitive copying paper are produced by applying a colorless or pale-colored coloring dye and a color developing agent on paper as a support. In the process of producing the coating solution, a developer dispersion is prepared by dispersing the developer in an aqueous solution of a water-soluble polymer as a binder. In order to produce a recording paper having excellent sensitivity, it is necessary to make the developer particles in the developer dispersion liquid as fine as possible. A fine particle developer dispersion is prepared by pulverization.

[Problems to be solved by the invention]

As described above, in order to produce recording paper with excellent sensitivity,
It is desired to prepare a developer dispersion of fine particles.
4-Hydroxy-4'-isopropoxydiphenyl sulfone (hereinafter abbreviated as "HIS") is a known and excellent color developer, but when stored in the form of a prepared dispersion or when the dispersion is prepared. In some cases, crystal growth may occur during wet milling for crushing. In particular, in the case of submicron particles, the tendency becomes remarkable. Recording paper produced using a developer dispersion containing the grown crystals leads to the drawback of causing background staining.

An object of the present invention is to provide an HIS that does not cause the above problems.

[Means for solving the problem]

The present invention relates to a compound selected from bis (4-hydroxyphenyl) sulfone and metal salts thereof based on 100 parts by weight of HIS (hereinafter collectively referred to as "bisphenol S").
Is contained in an amount of 0.03 parts by weight or more to suppress the crystal growth of HIS, and is used for a developer containing bisphenol S.
An HIS composition, an HIS dispersion, and a method of wet-grinding HIS in water, wherein the wet-grinding is carried out in the presence of bisphenol S.

The HIS may contain bisphenol S in powder form, and in this case, the effect is exhibited when a dispersion is used. If the content of bisphenol S is 0.03 parts by weight or more based on 100 parts by weight of HIS, crystal growth in the dispersion can be suppressed, and even when the dispersion is stored for a long period of time, it is necessary to completely prevent crystal growth. It is preferably at least 0.05 part by weight. 1.0%
If the temperature exceeds the range, there is a crystal growth effect, but it is not economical, and if it is further increased, it causes a background stain on heat-sensitive recording paper and pressure-sensitive copying paper.

Bisphenol S may be added to and contained in HIS, but bis (4-hydroxyphenyl) sulfone, which is a kind of bisphenol S, is a raw material for the production of HIS,
In addition, the metal salts may be a by-product during the production of HIS, and the HIS containing bisphenol S may be produced by adjusting the production conditions of HIS or by adjusting the purification method after production.

As the metal salt of bis (4-hydroxyphenyl) sulfone (bisphenol S which is a metal salt), alkali metal salts, particularly, Na metal salt are industrially preferable, and two phenols of bis (4-hydroxyphenyl) sulfone are industrially preferable. Either one or both metal salts of the hydroxyl group may be used.

Although the dispersion medium of the present invention and the dispersion medium for wet grinding are water, it is preferable to add a dispersant and perform wet grinding in order to improve the dispersion of HIS. As the dispersant, a normal dispersant and a surfactant can be used, but in order to produce recording paper such as heat-sensitive recording paper and pressure-sensitive copying paper, an aqueous solution of a water-soluble polymer to be used as a binder is used. It is a usual method to disperse the developer and wet-pulverize to prepare a dispersion of developer fine particles. In the present invention, when the purpose of producing these recording papers is, the water-soluble It is preferable to wet crush in an aqueous solution of a water-soluble polymer using a molecule as a dispersant.
Examples of the water-soluble polymer include polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyacrylamide, those used as binders for developers such as starches, the most common being polyvinyl alcohol. is there.

Further, other general additives to be added to the developer dispersion may be added to the dispersion medium.

The wet pulverization method in the present invention is not particularly limited, and a ball mill, a sand mill, and other ordinary wet pulverization methods can be employed.

The concentration of HIS at the time of wet pulverization is not particularly limited, but it may be carried out at a concentration of a developer dispersion suitable as a coating liquid for producing recording paper.

Hereinafter, the present invention will be described in more detail with reference to Examples,
The present invention is not limited to this.

Example 1 250 ml of 41.5 g of 15% polyvinyl alcohol aqueous solution, 40 g of pure water, 150 g of glass beads (1.0 to 1.5 mmφ) and 18.5 g of HIS
Measured in a polyethylene bottle. 0.019 g of bisphenol S (bis (4-hydroxyphenyl) sulfone) was added thereto, and the mixture was wet-pulverized with a Red Devil paint conditioner (manufactured by Igarashi Kikai) for 8 hours at room temperature. The average particle size after pulverization was about 1 μm (50% average particle size by Shimadzu particle size analyzer SALD-1000). Furthermore, the above glass beads are replaced with zirconium beads (0.6 to
0.8 mmφ) and the same pulverization was performed for 15 hours to obtain a dispersion having an average particle size of 0.6 μm. No crystal growth occurred when the dispersion was left for one month.

Comparative Example 1. Bisphenol S (bis (4-hydroxyphenyl)
When wet grinding was performed in the same manner as in Example 2 without adding sulfone), the particles were ground to about 1 μm by grinding for 8 hours with glass beads, but after 15 hours of grinding with zirconium beads, the average particle size was 3 μm. Met.

〔effect〕

The sensitivity of heat-sensitive recording paper and pressure-sensitive copying paper is better as the applied developer particles are smaller.

When the HIS composition for a developer of the present invention is used, there is no crystal growth even when stored in an aqueous solution, and according to the method of the present invention, even if HIS is sufficiently wet-pulverized, the prepared dispersion Since no crystal growth occurs in the liquid, an HIS dispersion of fine particles can be easily prepared.

Therefore, a highly sensitive recording paper can be manufactured by using the developer dispersion obtained by the method of the present invention.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nobuyuki Hirai 3-1-1, Ukima, Kita-ku, Tokyo Nippon Soda Co., Ltd. Tokyo Plant (56) References JP-A-62-280070 (JP, A) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) B41M 5/124-5/165

Claims (4)

(57) [Claims] (1) 100 parts by weight of 4-hydroxy-4'-isopropoxydiphenylsulfone, wherein 0.03 to 1 part by weight of a compound selected from bis (4-hydroxyphenyl) sulfone and a metal salt thereof is contained. Characteristic composition for color development. 2. The method according to claim 1, wherein 0.03 to 1 part by weight of a compound selected from bis (4-hydroxyphenyl) sulfone and metal salts thereof is present in 100 parts by weight of 4-hydroxy-4'-isopropoxydiphenylsulfone. A 4-hydroxy-4'-isopropoxydiphenyl sulfone dispersion, which is characterized by the following. 3. A method for wet-grinding 4-hydroxy-4'-isopropoxydiphenyl sulfone in water,
A wet grinding method for 4-hydroxy-4'-isopropoxydiphenyl sulfone, which comprises wet grinding in the presence of a compound selected from bis (4-hydroxyphenyl) sulfone and metal salts thereof. 4. The amount of a compound selected from bis (4-hydroxyphenyl) sulfone and metal salts thereof is 4-hydroxy-4'-isopropoxydiphenylsulfone 100.
4. The method according to claim 3, wherein the amount is from 0.03 to 1 part by weight based on part by weight.