JPH03288556A - Wet pulverizer, method for pulverizing solid substance using this apparatus and recording body coated with water dispersion of solid substance - Google Patents

Abstract

PURPOSE:To perform fine pulverization with good efficiency by forming a flow passing through a gap between a rotating disc and the inner wall from the introducing side, a flow reaching the discharging side from an opening of the disc and a flow returning from another opening of the disc to the introducing side to the mixture in a vessel. CONSTITUTION:A mixture of a fluid dispersion of a matter to be pulverized and pulverizing media introduced in a cylindrical vessel 1 from an introducing opening 7 is mixed and stirred by means of a rotating disc 2 to perform size reduction treatment and the dispersion and media after size reduction are separated by means of a screen 8 provided on the discharging side. At least one disc openings of which are worked for forming a flow passing through a gap between the apex part of the disc 2 and the inner wall of the vessel from the introducing side to the discharging side, a flow passing through the opening 3 of the disc from the introducing side to the discharging side and a flow returning through the opening 4 of the disc 2 from the discharging side to the introducing side is provided on a driving shaft 5. As the result, an efficient pulverization can be performed by using a few number of sand mills.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to an apparatus for wet pulverization of solid substances, and more particularly to an apparatus for efficiently wet pulverization of an aqueous dispersion of a solid substance using a sand mill filled with grinding media. It is something. The present invention also relates to a method of pulverizing a solid substance using this apparatus, and various recording bodies obtained by applying an aqueous dispersion of an extremely uniformly pulverized solid substance.

``Prior art'' In various recording media such as heat-sensitive recording paper and pressure-sensitive copying paper, and various recording media such as video and audio tapes, various organic pigments, organic dyes, organic color developers, and organic fusible substances are used. Various organic solid substances are used.

It is desirable to use these substances as a water or solvent dispersion that is as uniformly fine as possible, and generally has a particle size of several μm.
It is used after being made finer than m.

Various methods are known as wet pulverization methods for organic solid substances. For example, an organic solid substance is dispersed in water or a solvent, and then wet pulverized using a pulverizer such as a ball mill, an attritor, or a sand grinder. A method is proposed.

Usually, as a method for carrying out the fine grinding process efficiently, an attritor is used rather than a ball mill, and for a more efficient grinding process, a flow tube type sand mill in which a cylindrical henocell is filled with grinding media is used. In addition, among the flow tube type sand mills, the so-called horizontal sand mill in which Henocel is placed horizontally can increase the filling rate of the grinding media.
It has become widely used because it allows for more efficient processing than vertical sand mills.

Conventionally, when continuously processing an aqueous dispersion of an organic solid substance using the above-mentioned wet crusher, multiple crushers of the same type were arranged in series or parallel across pans, and a certain amount of crushed material was processed every minute. A common method is to send the dispersion liquid using a pump or the like and pulverize it.

In order to further increase the degree of atomization, the number of crushers used can be increased, or the throughput per minute per unit can be reduced to lengthen the residence time in the vessel undergoing the crushing action. As a result, it passed through the gap formed between the inner wall of the henocell and the end of the rotating disk (so-called
Refers to the phenomenon in which coarse particles cause short baths. 〉Prevents the mixing of coarse particles and achieves uniform refinement.

In recent years, with the remarkable increase in speed of recording equipment, there has been a demand for a significant improvement in recording sensitivity.In particular, in thermal recording materials, organic dyes and organic color developers have an average particle diameter of 1 μm or less, 0.3 μm.
There are also requests for ultra-fine processing down to the order of m.

A horizontal sand mill filled with grinding media, which is the most common grinder used in the wet grinding method, is capable of refining particles to an average particle diameter of about 2 μm.

However, it is not easy to uniformly pulverize to fine particles of 1 μm or less because coarse particles that have undergone a short bath are mixed in, and the current situation is that an extremely long pulverization process is required.

For example, even if repeated pulverization is performed using a flow tube type sand mill with a vessel capacity of 50j' filled with 55g of glass beads with a diameter of 1.5 to 1.7n, 1.
In order to obtain fine particles of about 5 μm or less, an extremely long pulverization process is required, and the number of pulverization times of 10 or more is required, which is unproductive and poses a serious problem in practice.

Therefore, methods that have been adopted to promote fine pulverization or ultrafine pulverization include increasing the filling rate of the grinding media filled inside the vessel, increasing the rotation speed of the disk, or reducing the material of the grinding media as much as possible. This method involves replacing beads with higher specific gravity, such as zirconia or metal beads, rather than glass beads. All of them have problems, and there is still room for improvement.

In other words, when the filling rate of the grinding media is increased, the movement of the media does not go smoothly in proportion to this, and the load on the rotational power of the disk increases.On the other hand, when the rotation of the disk is increased, the power load increases. This is not preferable because the grinding liquid generates heat. Additionally, beads made of zirconia or metal are expensive and have problems such as rust.

Regarding the size (diameter) of the pulverizing media, although the pulverization efficiency may be extremely remarkable when using fine media, the efficiency is not always high. For example, in a flow tube type sand mill with a vessel capacity of 100 A, instead of glass beads with a diameter of 1.5 to 2.0 mm,
Coarse pulverization using glass beads with a diameter of 0.64 mm is not preferable because the pulverization efficiency is rather poor and the separation mechanism is clogged.

Furthermore, when an aqueous dispersion having an average particle size of 1.6 μm that has been coarsely pulverized is pulverized using glass beads with a diameter of 0.6 to 0.8, the average particle size of the aqueous dispersion is 0. ．．
Although particles up to about 8 μm can be pulverized very efficiently, the efficiency decreases in the process of making particles smaller than that, and it becomes extremely difficult to make particles smaller than 0.8 μm.

Furthermore, when using microscopic media, a separation screen with very fine mesh is used depending on the size of the microscopic media, but in such a case, the screen is likely to become clogged. For example, when using a horizontal sand mill, the media is flown to the discharge side together with the aqueous dispersion, and the media and the aqueous dispersion are separated by a separation screen, so only the media concentrates on the discharge side. This will promote clogging.

When clogging occurs, the pressure inside the vessel increases, resulting in damage to the shaft sealing mechanism of the drive shaft and an increase in the temperature and viscosity of the aqueous dispersion in the mill, causing problems. .

Various proposals have been made to solve the above problems.

For example, Japanese Patent Application Laid-Open No. 63-93337 discloses a method of improving grinding efficiency by providing protrusions or holes on a stirring disk to impart strong shear force to the media and create turbulent flow. No. 2, No. 2003-116016 discloses a method of providing a hole with three or more inclined surfaces in a disk to facilitate movement of the media.

Further, Japanese Patent Application Laid-Open No. 55-145544 proposes a method of alternately arranging flat disks and stirring disks having holes with inclined surfaces to prevent the material to be crushed from making a short pass.

The above method is effective to some extent in promoting fine pulverization, but coarse particles that have short-passed inside the benzel are mixed,
During the mill movement to promote micronization using fine grinding media, the fine grinding media will concentrate near the liquid outlet, resulting in increased viscosity of the dispersion to be ground, poor stirring in the vessel, and short passes. Such defective phenomena occur, and it is extremely difficult to uniformly and efficiently atomize particles down to submicron size.

``Problems to be Solved by the Invention'' The present invention provides a wet pulverization device for solid substances, which prevents the mixing of coarse particles due to short paths, etc., and improves crushing efficiency.
The present invention provides a method for pulverizing a solid substance using this apparatus, and a recording medium obtained by applying an extremely uniformly pulverized solid@IJ quality aqueous dispersion.

"Means for Solving the Problems" The present invention performs a pulverization process by mixing and agitating a mixture of a dispersion to be pulverized and a pulverizing media introduced into a cylindrical vessel from an inlet into a cylindrical vessel using a rotating disk. In a wet pulverization device that separates the dispersion liquid and media after pulverization using a screen, the mixture is transferred from the introduction side to the tip of the rotating disk (2) in the henocell (1) through the gap formed between the inner wall of the cell and the tip of the rotating disk (2). to the discharge side, a flow from the inlet side to the discharge side through the disk opening (3), and a flow from the discharge side to the disk opening (4) and return to the inlet side. A wet pulverizer characterized in that at least one disk with a machined opening is provided on the drive shaft (5), and a solid substance is pulverized using a plurality of the pulverizers. The present invention discloses a method of pulverizing a solid material, and a recording medium coated with an aqueous dispersion containing fine particles of the solid material obtained by pulverization in this manner.

"Function" The wet pulverization device of the present invention, the method of pulverizing a solid substance using this device, and the recording medium coated with an aqueous dispersion containing fine particles of the solid material obtained by pulverization in this manner are described in this section. This will be explained in more detail based on FIG.

As shown in FIG. 1, the sand mill used as the wet pulverization device (6) of the present invention has its interior filled with fine beads called grinding media, and the inlet (7)
This is a horizontal sand mill that performs the grinding process by mixing and stirring a mixture of a dispersion to be ground and grinding media introduced into a cylindrical vessel (1) with a rotating disk (2).

In such a sand mill, the mixture is passed through the vessel from the inlet side to the discharge side through the gap between the tip of the disk and the inner wall of the vessel, and the other flow is from the inlet side to the discharge side through the opening (3) of the disk. Openings are then machined in the rotating disk to accommodate the recirculating flow from the discharge side through the opening (4) in the disk to the inlet side.

The details are shown in Figure 2, the rotary disk is provided with a hole in its center for passing the drive shaft (5), and also for forming a recirculating flow from the discharge side to the inlet side. The opening (4) is concentrically arranged at 90° around the drive shaft.
3, which is a sectional view taken along line AA' in FIG. 2, is processed. In order to create a flow that recirculates from the discharge side to the inlet side, an inclined surface is machined, as shown in FIG. 4, which is a sectional view taken along line cc' in FIG. 2.

Further, on the outside thereof, openings (3) for forming a flow from the introduction side to the discharge side are provided every 90'' on a concentric circle around the drive shaft, as shown in the sectional view taken along line B-B in Fig. 2. It is processed as shown in FIG.

In order to form a flow from the introduction side to the discharge side, an inclined surface is machined as shown in FIG. 6, which is a sectional view taken along line DD' in FIG. 2.

In the present invention, the angle of the slope of both openings is not particularly defined, but an angle in the range of 5 to 856 is used to recirculate the flow of the mixture through the opening (4) from the discharge side to the inlet side. This range is preferable in order to form a flow from the inlet side to the outlet side through the opening (3), but from the viewpoint of workability of the slope, 45 degrees is particularly preferably used.

The positions of the openings in the disc are such that the flow recirculates the mixture flow within the henocell from the discharge side to the inlet side;
It is desirable to take measures to shape the flow from the inlet side to the discharge side and to avoid creating a stop point in the flow. Therefore, it is preferable that the opening (4) be provided at a position within a range of 15 to 50% from the axis, more preferably within a range of 30 to 40%, assuming that the size of the radius of the disk is 100%. be. In addition, although it is not preferable to provide the opening (3) on the outside, it is preferably 60 to 90% in terms of disk processing, and more preferably 60 to 90%.
It is provided at a position of 5 to 80%.

The size of the opening is such that more flow is recirculated from the discharge side to the inlet side through the opening (4) than through the opening (3) from the inlet side to the discharge side. It is desirable that the opening (4) be set smaller than the opening (3) so that the opening (4) is smaller than the opening (3). In any case, the combined size of both openings is preferably set to 50% or less of the size of one side of the disk for reasons such as the strength of the disk.

The number of openings is not particularly limited, as long as a plurality of openings are provided, but an even number such as 4, 6, 8, 10° 12, etc. may be used to facilitate smoothness during rotation of the disk. It is desirable to provide it in a contrasting position.

Further, the cross-sectional shape of the opening is not particularly limited, and may be circular, polygonal, oval, etc., but circular is particularly preferred because it is easy to process.

As shown in FIG. 1, for example, seven such rotating disks are fixed to the drive shaft of a horizontal sand mill and then rotated by a drive motor (not shown) to pulverize the aqueous dispersion. It has been found that an aqueous dispersion with a sharp particle size distribution and a small average particle diameter can be obtained extremely efficiently without concentrating near the discharge port or with coarse particles being mixed in due to a short pass.

Although the reason why the aqueous dispersion can be pulverized extremely efficiently is not necessarily clear, it can be estimated as follows.

That is, in the case of the conventional method, there is a large difference in the circumferential speed of the disk between the outer periphery and the axial center of the disk, and a crushing force acts strongly on the aqueous dispersion located at the outer periphery of the disk. However, the crushing force only acts weakly on the aqueous dispersion located inside, especially near the drive shaft, and the force to move and stir the media and aqueous dispersion is weaker than that at the outer periphery of the disk. Since the crushing force is weak, the aqueous dispersion is discharged to the outside from the discharge port without being subjected to strong crushing force.

However, in the case of the device of the present invention, the aqueous dispersion is
4) and is recirculated at a high speed of more than 10 times per minute, it is estimated that the frequency with which the aqueous dispersion is subjected to the crushing force is higher than in the past, and that uniform pulverization can be achieved.

As described above, the sand mill of the present invention is an apparatus that can efficiently pulverize solid substances with uniform distribution of media and no clogging of the separation screen (8).

Further, when wet-pulverizing a solid substance using the sand mill of the present invention, a method of recirculating an aqueous dispersion liquid in an amount at least twice the amount of the aqueous dispersion liquid to be treated by passing through the opening (4). This is also the reason why the larger the amount of recirculation, the less coarse particles are mixed in due to short paths.

However, if the amount of the aqueous dispersion to be treated is too large, an excessive load will be placed on the separation screen for separating the media and the aqueous dispersion, which is not preferable.

Further, if the recirculation amount is less than twice, it is difficult to obtain the recirculation effect of the present invention, so it is not desirable to use less than this.

The amount of aqueous dispersion that is recirculated through the opening (4) is determined as described above. It is desirable to set the total amount of the liquid and the aqueous dispersion that passes through the opening (3) i1) to preferably 2 to b, more preferably 5 to b.

In addition, as shown in FIG. 7, in the method of continuously pulverizing an aqueous dispersion by arranging four sand mills of the present invention in series, the final stage sand mill, unlike the other mills, (9) But storage tank 0
Piping is installed inward. Therefore, when processing a low-viscosity aqueous dispersion, or when an aqueous dispersion that initially had a high viscosity rises in temperature during dispersion processing and as a result changes to a low viscosity, the vessel The aqueous dispersion sent out from the discharge port is not recirculated internally, and almost the entire amount is sent into the storage tank, resulting in the aqueous dispersion in the vessel becoming empty or the flow rate of the dispersion fluctuating. It becomes a problem.

In such cases, install a pressure control valve 0υ in the piping between the mill and the storage tank, and a flow control valve (2) downstream.
If the internal pressure of the vessel is adjusted to a value higher than Q, l kg/cm", preferably 1.5 to 2.5 kg/cxr2, the internal recirculation of the aqueous dispersion is extremely good. Grinding process becomes possible.

Further, when the aqueous dispersion of the organic solid substance thus obtained is applied to various recording bodies, products with extremely high sensitivity (high concentration) can be obtained, and such recording bodies will be described in detail below.

Various dispersants are used to obtain an aqueous dispersion of an organic solid substance, such as polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, acrylic acid derivatives, sulfonic acid derivatives, maleic anhydride derivatives, etc. , various water-soluble polymer compounds such as gelatin, and various surfactants such as anionic surfactants and nonionic surfactants are appropriately selected and used. The amount of dispersant added to the aqueous dispersion is preferably the minimum necessary amount. However, wet grinding by a mill increases the surface area of the organic solid material, and the amount of dispersant required increases as the grinding progresses. Therefore, it is preferable to additionally add a dispersant during the pulverization process.

On the other hand, depending on the type of dispersant, the fluidity form of the aqueous dispersion may change. For example, polyvinyl alcohol has a large dispersing power, but if added in a large amount, it becomes giratant fluid. On this point, methylcellulose-based materials are weak against mechanical shearing force, but exhibit pseudoplastic flow, and have the advantage of not increasing viscosity even at high shear rates, and are suitable for media separation mechanisms with small openings. It does not cause clogging and is one of the preferred dispersants.

According to the study results of the present inventors, it is preferable to add the dispersant in portions to the organic solid material aqueous dispersion when processing with a sand mill, rather than adding the entire amount from the beginning. When using 3 to 6 mills in succession for wet milling, add 40 to 60% by weight of the total dispersant required immediately before coarse milling with a sand mill, and add the remaining dispersant. When micronized, if added in portions to an aqueous dispersion of organic solid materials just before each mill, foaming and thickening phenomena (sludge) occur.
It has become clear that miniaturization can be achieved extremely efficiently without problems such as clogging in thin separation mechanisms. Of course, when adding the dispersant, it is possible to appropriately adopt a method of adding the dispersant in addition to the method described above, which improves efficiency by further dividing the dispersant.

The organic solid substances to be pulverized in the method of the present invention include various solid organic substances, and in particular, organic pigments, organic dyes, etc. used in various recording bodies such as heat-sensitive recording bodies and pressure-sensitive copying papers, When the method of the present invention is applied to the miniaturization of various organic substances such as organic color developers and organic thermofusible substances, extremely remarkable effects can be obtained. Note that the method of the present invention can also be applied to the miniaturization of liquid substances that become solid by lowering the temperature.

Various types of organic dyes are known for use in heat-sensitive recording media, pressure-sensitive copying paper, etc. For example, 3,3-bis(p-dimethylaminophenyl) is a colorless to light-colored basic dye. -6-dimethylaminophthalide, 3,3
-bis(p-dimethylaminophenyl)phthalide, 3-
(p-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindole 3
-yl) phthalide, 3,3-bis(1,2-dimethylindol-3-yl)-5-dimethylaminophthalide,
3.3-bis(1,2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3.3-bis(9-
Ethylcarbazol-3-yl)-6-dimethylaminophthalide, 3,3-bis(2phenylindole-3-
triallylmethane dyes such as yl)-6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(1-methylpyrrol-3-yl)6-dimethylaminophthalide, 4,4'-bis -dimethylaminobenzhydrylbenzyl ether, N-halophenyl leuco auramine, N-2,4,5-) diphenylmethane dyes such as IJ chlorophenyl leuco auramine, thiazine such as benzoyl leucomethylene blue, p-nitrobenzoyl leuco methylene blue, etc. dye, 3-methyl-spiro-
Dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-hensylspiro-dinaphthopyran, 3-methyl-naphtho(6'
-Methoxyhenz) spiro-based dyes such as spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B
Anilinolactam, rhodamine (p-nitroanilino)
Lactam, rhodamine (O-chloroanilino) Lactam dyes such as lactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-7-methoxyfluoran, 3-diethylamino- 7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3
-diethylamino-7,8-benzofluorane, 3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3-diethylamino-6,7-dimethylfluorane, 3-(N-ethyl-p-toluidino) )-7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethyl a no? -N-methyl-N-benzylanofluorane,
3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-phenylaminofluoran Oran, 3-(N-cyclobenti-N-ethylamino)-6
-Methyl-7-anilinofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-(p-)luidino)fluorane, 3-diethylamino-6-methyl-
7-phenylaminofluorane, 3-diethylamino-
7-(2-carbomethoxy-phenylamino)fluorane, 3(N-ethyl-N-isoamylamino)-6-methyl-7-phenylaminofluorane, 3-(N-cyclohexyl-N-methylamino)- 6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-
7-phenylaminofluorane, 3-piperidino-6-
Methyl-7-phenylaminofluorane, 3-diethylamino-6methyl-7-xylidinofluorane, 3-diethylamino-7-(o-chlorophenylamino)fluoran, 3-dibutylamino-7-(o-chlorophenylamino)fluoran , 3-pyrrolidino6-methyl-7
-p-butylphenylaminofluorane, 3-N-methyl-N-tetrahydrofurfurylamino-6-methyl-
Examples include fluoran dyes such as 7-anilinofluorane and 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane.

Various organic color developers are also known that develop color upon contact with basic dyes, such as 4-tertbutylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, and 4-hydroxyacetophenol. , 4-tert-octylcatechol, 2,2'-dihydroxydiphenol, 2,2-methylenebis(4-
Methyl-5-tertisobutylphenol), 4.4
'-isopropylidene bis(2-tert-butylphenol), 4.4'5ec-butylidene diphenol,
4-phenylphenol, 4,4'-isopropylidenediphenol (bisphenol A), 2.2'-methylenebis(4-chlorophenol), hydroquinone, 4.4-cyclohexylidenediphenol, benzyl 4-hydroxybenzoate , dimethyl 4-hydroxyphthalate, hydroquinone monobenzyl ether, 4-hydroxyphenyl-4'-isopropyloxyphenylsulfone, novolac type phenolic resin, phenolic compounds such as phenol polymers, benzoic acid, p -tert-
Butylbenzoic acid, trichlorobenzoic acid, terephthalic acid,
3-5ec butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, salicylic acid, 3isopropylsalicylic acid, 3-tert-butylsalicylic acid, 3
-Benzylsalicylic acid, 3-(α-methylbenzyl)salicylic acid, 3-chloro-5-(α-methylhensyl)salicylic acid, 3,5-di-tert-butylsalicylic acid, 3
- Aromatic carboxylic acids such as phenyl-5 (α, α-dimethylhensyl) salicylic acid, 3,5-di α-methylbenzyl salicylic acid, and these phenolic compounds, aromatic carboxylic acids such as zinc, magnesium, aluminum, etc. Examples include organic acidic substances such as salts with polyvalent metals such as calcium, titanium, manganese, tin, and nickel.

Furthermore, examples of organic thermofusible substances include zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, waxes such as ester wax, stearamide, methylene bisamide stearate, oleic acid amide, and palmitin. Fatty acid amides such as certain acids and coconut fatty acid amides, 2.
2′-methylenebis(4-methyl-5-tert-
butylphenol), 4.4'-butylidenebis(6-tertbutyl-3-methylphenol), 1
．． 1.3- ) Lis(2-methyl-4-hydroxy-5
Hindered phenols such as -tert-)thylphenol)butane, ultraviolet absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-hydroxy 4-hensyloxybenzophenone, dihenzil Terephthalate, 1,2-di(3methylphenoxy)ethane, 1,2-diphenoxyethane, 1-phenoxy-2-(4-methylphenoxy)ethane, 4.4'-
Ethylenedioxybis-benzoic acid diphenylmethyl ester, terephthalic acid dimethyl ester, terephthalic acid dibutyl ester, terephthalic acid dibenzyl ester, p
-benzyl-biphenyl, 1,4-dimethoxynaphthalene, 4-jethoxynaphthalene, 1-hydroxynaphthoic acid phenyl ester, and various other known compounds.

In the various aqueous dispersions of organic solid substances obtained by the method of the present invention, the organic solid substances are extremely uniformly finely divided.
It holds various recording media such as heat-sensitive recording media and pressure-sensitive copying paper, and is effectively used in a wide range of technical fields. In particular, when applied to heat-sensitive recording materials that require a strong demand for fine grained materials, extremely excellent recording sensitivity can be obtained, making it one of the most effective embodiments of applying the method of the present invention. be.

Note that as long as the aqueous dispersion of the organic solid material finely divided by the method of the present invention is used, the method for producing the heat-sensitive recording material is not particularly limited, and various known methods can be appropriately selected and applied.

Incidentally, the usage ratio of the basic colorless dye and the color developer in the recording layer is generally 1 to 50 parts by weight of the basic colorless dye!
The amount is preferably about 1 to 10 parts by weight, and in addition to the basic colorless dye and the color developer, adhesive components such as starches, hydroxyethyl cellulose, methyl cellulose, etc. are contained in the coating liquid forming the recording layer. Carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, diisobutylene/maleic anhydride copolymer salt, styrene/maleic anhydride copolymer salt, ethylene/acrylic acid copolymer salt, styrene/acrylic acid copolymer salt Added salt, natural rubber emulsion, styrene/butadiene copolymer emulsion, acrylonitrile/butadiene copolymer emulsion, methyl methacrylate/butadiene copolymer emulsion, polychloroprene humalditane, vinyl acetate emulsion, ethylene/vinyl acetate emulsion, etc. be done. In addition, as a pigment component,
For example, diatomaceous earth, calcined diatomaceous earth, kaolin, bottom kaolin,
Inorganic pigments such as white carbon, magnesium carbonate, calcium carbonate, zinc oxide, aluminum oxide, titanium oxide, silicon oxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, clay, bottom clay, styrene microballs, nylon powder, polyethylene powder,
Organic pigments such as urea/formalin resin fillers and raw starch granules are added, but of course they are not limited to these exemplified substances, and two or more types can be used in combination if necessary. be.

Furthermore, various other auxiliary agents can be appropriately added to the recording layer coating solution, such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate,
Dispersants such as sodium lauryl alcohol sulfate ester, alginates, fatty acid metal salts, various heat-fusible substances as described above, antifoaming agents, fluorescent dyes, color dyes, etc., may be used.

The method of forming the recording layer is not particularly limited either, and the TEN forming coating liquid described above is applied onto the support and dried using an appropriate coating device such as an air knife coater, blade coater, roll blade, bar coater, gravure coater, or multilayer coater. It is formed by a method such as The amount of coating liquid applied is not particularly limited, and is generally 2 to 12 g/n in terms of dry weight.
? The amount is adjusted preferably within a range of about 3 to 10 g/m.

The support is not particularly limited, and may include paper such as high-quality paper, base paper made with a Yankee machine, single-sided glossy base paper, double-sided glossy base paper, cast-coated paper, art paper, coated paper, medium-quality coated paper, and synthetic fibers. Paper, synthetic resin film, etc. are used as appropriate. In addition, after coating and drying the recording layer, smoothing treatment such as super calendering may be performed as necessary, an overcoat layer may be provided on the recording layer for the purpose of protecting the recording layer, etc. Various known techniques in the field of heat-sensitive recording materials can be added, such as providing an undercoat layer or a backcoat layer.

The heat-sensitive recording material of the present invention obtained in this way has extremely good recording sensitivity and high-speed recording because it uses a uniformly finely divided aqueous dispersion of a basic dye, a color developer, a thermofusible substance, etc. It has excellent characteristics that make it suitable for recording.

"Examples" The present invention will be described in more detail with reference to Examples below, but it is of course not limited to these Examples. Further, unless otherwise specified, parts and % in the examples represent "parts by weight" and "% by weight", respectively.

(Example 1) [Fine pulverization treatment of basic dye dispersion] 3-dibutylamino-6-methyl-7-phenylaminofluorane 100 parts 1,2-bis(
250 parts of 3-methylphenoxy)ethane 2% aqueous solution of methylcellulose 200 parts Sodium di(tridecyl)sulfosuccinate 10 parts water
An aqueous dispersion of a basic dye consisting of 200 parts was prepared in a dispersion tank, and the aqueous dispersion thus prepared was passed through a horizontal sand mill (as shown in Fig. 1).
Vessel shape: Inner diameter 30cm x length 75cm x capacity 5
ON, rotating disk; diameter 27o x thickness 2c1) x number of 7 pieces, opening (4); diameter 5ell x 4 pieces, the position is 5c from the rotation axis! At 1), the opening (3)
; Diameter 2c1) x 4 pieces, their position is 1) from the rotation axis center
cm, the angle of the slope of both openings is 45
) were arranged in series as shown in Figure 7, and while feeding the aqueous dispersion liquid at a processing flow rate of 180 kg/hour using the supply pump a3, the water was fed through the opening (4) in the vessel to the inlet side. While being recirculated, it moved to the discharge side through the opening (3) and was passed through four mills in succession for pulverization.The mill conditions at this time were: The material of the grinding media was glass beads; Its average particle diameter and filling rate are 0.5-0.7fi
and 85%, and the peripheral speed was 10 m/sec.

In addition, the pressure is set to 1.5 kg/■2 and the discharge amount is adjusted using the pressure regulating valve αυ and flow regulating valve (2) installed on the piping leading to the storage tank of the final stage mill. did.

In this way, serial wet continuous pulverization was performed to obtain an aqueous dispersion of a basic dye having an average particle size as shown in Table 1 and a cumulative particle size of 90%.

In addition, the particle diameter at 90% accumulation refers to the diameter of each individual particle, the particle diameter distribution is drawn from the measurement results, and the particle diameter is accumulated sequentially from the smallest distribution width to the total particle volume. This is the particle size when it reaches 90%. Further, the particle diameter when the volume becomes 50% of the total particle volume is the average particle diameter.

(Example 2) Series wet continuous pulverization was carried out in the same manner as in Example 1, except that the number of both openings of the rotating disk used was reduced to two, and the average particle diameter was obtained as shown in Table 1. An aqueous dispersion of a basic dye having a cumulative particle size of 90% was obtained.

(Example 3) Series wet continuous pulverization was carried out in the same manner as in Example 1, except that the position of the opening (3) of the disk used was changed to 12 cm from the rotation axis. An aqueous dispersion of a basic dye having the average particle size and the cumulative particle size of 90% as shown was obtained.

(Comparative Example 1) Series continuous pulverization was carried out in the same manner as in Example 1, except that seven flat conventional discs were used, and Table 1
An aqueous dispersion of a basic dye having an average particle diameter and a cumulative particle diameter of 90% was obtained.

In this case, the temperature of the aqueous dispersion that came out from the outlet was 3 to 8° C. higher than in the example, probably because the grinding media was concentrated near the outlet during continuous operation over a long period of time.

(Comparative Example 2) In Example 1, serial continuous pulverization was carried out in the same manner as in Example 1, except that all seven disks were used that did not have an inclined surface processed into the disk opening, and the average particle diameter and the like shown in Table 1 were obtained. An aqueous dispersion of a basic dye having a cumulative particle size of 90% was obtained.

(Example 4) [Fine pulverization treatment of color developer dispersion] 4-hydroxy-4'-isopropoxydiphenylsulfone 400 parts Methyl cellulose 2% aqueous solution i 20 (l (! Dioctylsulfosuccinate sodium 5 parts water
An aqueous dispersion of a color developer consisting of 250 parts was prepared in a dispersion tank, and the prepared aqueous dispersion was heated at a flow rate of 180 kg/hour under the same conditions as for the basic dye dispersion applied in Example 1. Then, the mixture was continuously passed through four mills to perform a fine pulverization treatment, thereby obtaining an aqueous developer dispersion having an average particle diameter and a cumulative particle diameter of 90% as shown in Table 1.

(Example 5) Fine pulverization was carried out in the same manner as in Example 4, except that the position of the opening (3) of the disk used was changed to 12C1) from the rotation axis, and the results are shown in Table-1. An aqueous color developer dispersion having the average particle size and the cumulative particle size of 90% as shown was obtained.

(Comparative Example 3) Continuous pulverization was carried out in the same manner as in Example 4, except that all seven flat conventional disks were used, and the average particle diameter as shown in Table 1 and the cumulative 90% An aqueous color developer dispersion having a particle size of .

In this case, the temperature of the aqueous dispersion during the pulverization process was 5 to 10[deg.] C. higher than in the example, so the temperature of the cooling liquid was lowered.

(Comparative Example 4) Series wet continuous grinding was carried out in the same manner as in Example 4, except that all seven disks were used whose disk openings were not machined with inclined surfaces, and the average particles as shown in Table 1 were obtained. An aqueous color developer dispersion having a particle size at 90% cumulative particle size was obtained.

In addition, the average particle diameter of the dye and color developer and the particle diameter at 90% cumulative time are as follows: MICROTRAC PARTICLE 5I
Measurement was carried out using ZE ANALYZER (manufactured by Nikki Co., Ltd.).

In addition, as mentioned above, coarse particles are mixed due to the short path, but the average particle diameter of the coarse particles is (al, cumulative 90%
When the particle diameter at the time is expressed as a peak), it is expressed as b/a as a guide, and the results are also shown in Table 1.

(Examples 6 and 7) To 712 parts of the color developer dispersion obtained in Example 5, 1000 parts of a 10% aqueous solution of methyl methacrylate/acrylamide copolymer and 100 parts of amorphous silicon oxide were added to this liquid in a dispersion tank. After stirring thoroughly using a propeller mixer and adding 30 parts of a 30% aqueous dispersion of zinc stearate, the aqueous dispersion of basic dye obtained by the method of Example 1 and Example 3 was prepared. 826 parts were added (Example 6 and Example 7, respectively) and stirred to prepare a coating liquid for thermal recording paper.

Next, 10% of amorphous silicon oxide was added to the 50g/1rd base paper.
After drying a 35% aqueous dispersion consisting of 0 parts of styrene-butadiene copolymer latex (solid content) and 2 parts of carboxymethyl cellulose (solid content) with a blade coater, the coating amount is 7 g/-. Coat and dry. The above coating liquid for thermal recording paper was coated and dried on the surface of the coating layer using a blade coater so that the coating amount after drying was 3.28/n, and then thermal recording was performed using a super calender. A smoothing treatment was performed so that the layer surface had a Henok smoothness of 450 seconds, and two types of thermal recording paper were obtained.

(Example 8.9) In Example 6.7, the basic dye aqueous dispersion obtained by the method of Example 1 and Example 3 was changed to 578 parts (Example 8 and Example 3, respectively). Example 9), Example 6
Two types of thermal recording paper were obtained in the same manner as in Example 7.

(Comparative Example 5) In Example 7, the dye of Comparative Example 1 was used instead of the aqueous basic dye dispersion of Example 3, and the developer of Comparative Example 3 was used instead of the aqueous developer dispersion of Example 5. A thermosensitive recording paper was obtained in the same manner as in Example 7 except that .

(Comparative Example 6) In Comparative Example 5, the dye of Comparative Example 2 was used instead of the aqueous basic dye dispersion of Comparative Example 1, and the developer of Comparative Example 4 was used instead of the aqueous developer dispersion of Comparative Example 3. Comparative Example 5 except that the agent was used.
A thermosensitive recording paper was obtained in the same manner as above.

[Evaluation of thermal recording paper]

The six types of thermal recording paper thus obtained were used in a commercially available thermal facsimile machine (product name: NEFAX-2゜manufactured by NEC Corporation).
The recorded density was measured using a Macbeth densitometer, and the results obtained are shown in Table 2.

"Effect" As is clear from the results in the table, when the sand mill of the present invention or a plurality of sand mills are used for pulverization, the pulverization can be carried out extremely efficiently with a small number of sand mills, and it is more effective than the comparative example. Thermal recording paper, which has an extremely small average particle diameter and fewer coarse particles, and which is manufactured using finely pulverized dyes and color developers, exhibits excellent recording sensitivity and extremely high recording density. Met.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a rotary disk having an opening with an inclined surface according to the present invention applied to a horizontal sand mill. FIG. 2 is a detailed view of the rotating disk of the invention. Figures 3 and 4 are A-A in Figure 2.
It is a figure which shows a 'cross section and a CC' cross section. FIGS. 5 and 6 are diagrams showing a BB' cross section and a DD' cross section in FIG. 2. FIG. FIG. 7 is a diagram showing a schematic flow of a pulverization method when four sand mills are arranged in series. (1) Vessel (2) (3) Outer opening (4) (5) Drive shaft (6) (7) Inlet (8) (9) Outlet α of αυ Pressure control valve (2) 0 Supply pump

Claims (9)

[Claims] (1) A mixture consisting of the dispersion to be crushed, liquid and crushing media introduced into the cylindrical vessel from the inlet is mixed and stirred with a rotating disk to perform the crushing process, and the dispersion after being crushed is passed through a screen installed on the discharge side. In the wet pulverization device that separates the mixture and the media, the mixture is
A flow from the introduction side to the discharge side through the gap between the tip of the rotating disk (2) and the inner wall of the vessel, a flow from the introduction side to the discharge side through the opening (3) of the disk, and a flow from the discharge side to the disk. A wet-type pulverization device characterized in that a drive shaft (5) is provided with at least one disk machined with an opening for forming a flow that returns to the introduction side through the opening (4). (2) The inner opening is machined with an inclined surface in the direction that forms a flow that recirculates from the discharge side to the inlet side, and the outer opening forms a flow that flows from the inlet side to the discharge side. 2. The wet pulverization apparatus according to claim 1, wherein the inclined surface is machined in a direction in which the pulverization is performed. (3) The wet pulverization apparatus according to claim 1 or 2, wherein the angle of the inclined surfaces of both openings is in the range of 5 to 85 degrees. (4) The position of the opening for forming the recirculating flow from the discharge side to the inlet side increases the size of the radius of the disk by 100
%, it is in the range of 15 to 50% from the axis, and the position of the opening for forming the flow from the inlet side to the discharge side is 60 to 90% from the axis. The wet pulverization apparatus according to claim (1) or (2). (5) In a method of wet-pulverizing an aqueous dispersion of a solid substance using multiple sand mills, an amount of the aqueous dispersion at least twice the amount of the mixture to be pulverized is passed through the inner opening. A method for wet pulverization of solid substances, characterized in that the solid substances are recirculated. (6) The method for pulverizing a solid substance according to claim (5), characterized in that in the final stage sand mill, the amount of the mixture sent to the tank is adjusted by a flow control valve provided in a pipe between the mill and the storage tank. . (7) The method for wet pulverization of a solid substance according to claim (5), wherein the solid substance is an organic pigment, an organic dye, an organic color developer, an organic fusible substance, or a mixture thereof. (8) A recording medium coated with an aqueous dispersion containing fine particles of an organic solid substance finely pulverized by the method of claims (5) to (7). (9) The recording medium according to claim (8), wherein the recording body is a heat-sensitive recording medium.