JP3034575B2 - Polymer fine particle manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Industrial applications]

The present invention relates to an apparatus for producing fine polymer particles such as a matting agent used for a photographic light-sensitive material.

BACKGROUND OF THE INVENTION

Generally, the outermost layer (uppermost layer or back layer) of a silver halide photographic material (hereinafter, simply referred to as a photographic material) uses a hydrophilic colloid represented by gelatin as a binder. Therefore, when the surface of the photosensitive material is in a high-temperature, high-humidity atmosphere, the adhesiveness or tackiness increases, and when the photosensitive material comes into contact with another object, it easily adheres thereto. This adhesion phenomenon occurs between the photosensitive materials or between the photosensitive materials and other objects that come into contact with the photosensitive materials during manufacturing, storage, photographing, processing, projection, or storage after processing. , Often a serious failure. In particular, in a color light-sensitive material, since a photographic layer contains a large number of additives such as a color coupler, the adhesion property has been a serious problem. In order to solve this problem, inorganic materials such as silicon dioxide, magnesium oxide, titanium dioxide, calcium carbonate, polymethyl methacrylate, cellulose acetate propionate, methyl methacrylate / methacrylic acid copolymer, etc. There has been proposed a method in which fine particles of an organic substance are contained to increase the roughness of the surface of the photosensitive material to form a so-called mat, thereby reducing the adhesiveness. In the case of color light-sensitive materials, it is necessary to use a large amount of a matting agent for the above-mentioned reason. Polymers such as polymethyl methacrylate and methyl methacrylate / methacrylic acid copolymer can be generally prepared by a method such as solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc. The solution polymerization method which is also excellent is often used. The solution polymerization method is a method of polymerizing in a solvent that dissolves both the monomer as a raw material and the polymer to be produced. This is done by pouring the mixture and precipitating the polymer. When the above-mentioned polymethyl methacrylate or methyl methacrylate / methacrylic acid copolymer is used as a matting agent, after polymerizing a solution (eg, methanol), the reactant is poured into a medium (eg, water) to obtain a polymer obtained as crystals. Is re-dissolved in a solvent (eg, ethyl acetate) having low miscibility with water, dispersed in fine particles in water together with a protective colloid such as gelatin, and adjusted to a required particle size (JP-A-58-6693).
No. 7, JP-A-60-126644). Also, as proposed in JP-A-61-77044,
A method has also been proposed in which a reaction product obtained by solution polymerization in a solvent that is substantially immiscible with water is directly dispersed in water containing a dispersant to form a matting agent. By the way, in the above-mentioned technology, the solvent is volatilized from the polymer oil droplets by drying the dispersion in the state of polymer oil droplets immediately after dispersion in water under reduced pressure, and finally a solid polymer is precipitated. In order to obtain polymer fine particles having a predetermined particle size, it is necessary to distill off the solvent while maintaining the dispersed state of polymer oil droplets by performing appropriate stirring. However, polymer oil droplets are unstable, especially when the solvent is distilled off, and coalescence of polymer oil droplets is likely to occur. The particle size of the polymer particles obtained after distilling off the solvent over a long period of time often has a large average particle size and a wide distribution, and the desired polymer fine particles cannot be obtained. There is. That is, there is a problem that the particle size of the polymer fine particles cannot be controlled with high accuracy.

DISCLOSURE OF THE INVENTION An object of the present invention is to provide polymer fine particles whose particle diameter is controlled with high precision, particularly polymer fine particles corresponding to the particle diameter of polymer oil droplets immediately after dispersion. An object of the present invention is an apparatus for producing polymer fine particles having an average particle size of 0.5 to 5 μm, corresponding to the particle size of polymer oil droplets immediately after dispersion, and having a solubility in water of 8 × 10 ⁻³ to 8 × 10 ⁻³ . 3.3 × 10 ^-1 (g / gH ₂ O)
A polymer oil droplet generating means for dispersing a polymer dissolved in an organic solvent in water to generate polymer oil droplets; [(weight of the organic solvent / solubility of the organic solvent in water) × 0.5− ( Water mixing means for mixing water in an amount up to 20 times the weight of the dispersion with respect to the dispersion obtained by the polymer oil droplet generation means. This is achieved by a manufacturing apparatus for the characteristic polymer fine particles. Hereinafter, the present invention will be described in more detail. As a result of intensive studies conducted by the present inventors, polymer fine particles whose particle diameter is precisely controlled, particularly polymer fine particles corresponding to the particle diameter of polymer oil droplets immediately after dispersion, are polymer oil droplets formed by dispersing in water. It was found to be obtained by adding water. By the way, conventionally, by drying a polymer oil droplet dispersion under reduced pressure, a solvent is volatilized from the polymer oil droplets, and finally solid polymer particles are precipitated to obtain an aqueous dispersion of the polymer particles. On the other hand, in the present invention, water is added to the polymer dispersion to elute the solvent in the polymer oil droplets into the continuous phase (aqueous phase), thereby precipitating solid polymer particles, and forming an aqueous dispersion of polymer particles. Is what you get. For this purpose, for example, devices as shown in FIGS. 1 and 2 have been considered. That is, as shown in FIG. 1, a polymer oil droplet dispersion quantitatively discharged from a disperser 1 by a pump 2 is mixed with water quantitatively discharged from a water tank 3 by a pump 4 and a continuous mixer. 5 are simultaneously supplied, solid polymer particles are precipitated in the continuous mixer 5, and an aqueous dispersion of the polymer particles is continuously discharged. In FIG. 2, the pump is omitted because the disperser 6 itself has a constant discharge function, and the industrial water can be supplied quantitatively. A configuration in which a water pipe is connected is shown. The continuous mixers 5 and 7 in the present invention are not particularly limited, but static mixers and static mixers are preferable because the apparatus can be simplified. The disperser in the present invention is not particularly limited, and may be a continuous type or a batch type. For example, an ultrasonic disperser, a Manton-Gauling, a double cylindrical disperser, a high-speed stirring type disperser and the like can be mentioned. When the apparatus of the present invention is used, the mixing ratio of the added water and the polymer oil droplet dispersion has an industrially appropriate range. In order to elute the solvent from the polymer oil droplets in the polymer oil droplet dispersion liquid and precipitate solid polymer particles, we investigated the amount of water to be added. If so, it was confirmed that solid particles of the polymer were precipitated. However, since a certain amount of water is present from the beginning in order to form a polymer oil droplet dispersion, the amount of water actually required is the value obtained by subtracting the amount of water initially present from the amount required for precipitation, that is, (Solvent weight / solubility)
× 0.5-(weight of water in the initial liquid). The solvent is eluted from the polymer oil droplets to precipitate solid polymer particles. The upper limit of the weight of added water is not limited in itself, but if a large amount of water is added, the added water treatment will be performed later. As a result, the upper limit of the weight of water added is up to 20 times the weight of the dispersion, which is industrially appropriate. For example, 40% by weight of a solvent is contained in 100 g of a polymer oil droplet dispersion, and H ₂ O
50% by weight, and the solvent solubility is 5 × 10 ^-2 g / gH
_In the case of ₂ O, the minimum weight of water to be added = [((100 × 0.4 / 5 × 10
⁻² ) × 0.5− (100 × 0.5)] = 350 g, and the maximum weight of water to be added is 20 × 100 = 2000 g. That is, in this case, the amount of water to be added is preferably 350 g or more and 2000 g or less. Incidentally, some additive may be added to the added water. In the present invention, the solubility in water is 8 × 10 ^{−3 to} 3.3 × 1.
Examples of the organic solvent of 0 ^-1 (g / gH ₂ O) include n-butanol, sec-butanol, ethyl acetate, ethyl methyl ketone, chloroform, diethyl ether and the like, but these may be used alone. , Or a mixture of a plurality of them. There is no particular limitation on the method of dissolving the polymer in an organic solvent poorly miscible with water, and the bulk polymerized polymer may be dissolved in the solvent, or the solution polymerized polymer in an appropriate solvent may be used. May be once precipitated and redissolved in an organic solvent as described above. More preferably, a reaction product obtained by solution polymerization in the above-mentioned solvent may be used as it is. The polymer used in the present invention is not particularly limited except that it is soluble in an organic solvent poorly miscible with water and insoluble in water. The matting agent includes, for example, homopolymers of methacrylic esters such as methyl methacrylate and ethyl methacrylate, and copolymers of methacrylic esters such as methyl methacrylate and ethyl methacrylate / methacrylic acid. The molecular weight of these polymers is 3000-7000
00, more preferably 5000-20000
It is preferred that When the polymer is dispersed in water, the polymer is usually dispersed under rapid stirring in water containing a dispersant (for example, a surfactant). In addition to the dispersant, gelatin or the like may be added as a protective colloid. The dispersant is usually 0.1 to 20 to the reaction mixture.
% By weight, preferably 1 to 10% by weight of surfactant is used. Examples of the surfactant include natural surfactants such as saponin, alkylene oxide derivative-based anionic surfactants (eg, polyoxyethylene oleyl ether, polyoxyethylene nonylphenyl ether, sorbitan monooleate, etc.), higher alkylamines, Cationic activators such as quaternary ammonium salts (eg, octadecylamine acetate, oxyethylene dodecylamine, octadecyl ammonium chloride, tetradecyldimethylbenzylammonium chloride), anionic activators containing acidic groups such as carboxylic acids and sulfonic acids ( For example, sodium dodecylbenzenesulfonate, sodium oleylmethyltaurate, sodium dioctylsulfosuccinate, etc.), amphoteric activators (eg, N-alkylaminopropionate, N-dimethyl) Chirubetain, etc.) and the like. The treatment of the aqueous dispersion containing the polymer fine particles obtained according to the present invention described above depends on the convenience of the subsequent steps. It may be used as it is, or may be used after removing the organic solvent in the aqueous dispersion by, for example, drying under reduced pressure. Alternatively, only the polymer fine particles may be taken out by means such as filtration or centrifugation. Further, a combination thereof may be performed. As the matting agent, the aqueous dispersion containing the matting agent obtained as described above is applied to a photosensitive material by any method known in the field of photography. In a multilayer photosensitive material in which the matting agent obtained by the present invention is applied to the outermost layer of the photosensitive material, for example, the surface protective layer and the back layer, the matting agent is preferably contained in the non-photosensitive intermediate layer of the final product. Preferably, it is added to the protective layer. For example, 50 for the outermost layer
It is preferably contained in an amount of from 500 to 500 mg / m ² , particularly preferably from 100 to 400 mg / m ² . The present invention is based on a two-stage system in which polymer oil droplets (primary particle size) are first formed, and then polymer solid particles (desired particle size) are formed. Here, such a system is adopted. In a one-stage method in which a polymer / solvent mixture is directly added and dispersed while stirring in excess water in advance, it is inevitably easily precipitated as a bulk polymer before being dispersed. This is because it is very difficult to obtain polymer fine particles having a diameter.

【Example】

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. [Example 1] Ethyl methacrylate (EMA) 34.2, methyl methacrylate (MMA) 30.0 g, methacrylic acid (MAA) 17.2 g, α, α '
2.0 g of azobisisobutyronitrile (AIBN) and 500 cc of ethanol were placed in a three-necked flask, and the mixture was refluxed for 10 hours. Thereafter, the reaction solution was poured into a large amount of water with vigorous stirring to precipitate a reaction product. Next, the precipitate was filtered, washed with water, and dried at 60 ° C. in air to obtain a copolymer. The yield was 92.7 g (94% of the theoretical yield), and the molar composition was determined by NMR to be EMA: MM.
A: MAA = 30:30:40. 10 g of this copolymer was mixed with 20 g of ethyl acetate and 20 g of n-butanol.
It melt | dissolved in 40 g of mixed solvents of g. Further, 0.1 g of sodium dodecylbenzenesulfonate was dissolved in 10 g of water. 15g gelatin in 300ml beaker
Was added, 150 g of water was added, the mixture was swollen for 30 minutes, and then dissolved at 60 ° C. Next, in an apparatus as shown in FIG.
The gelatin solution and the aqueous solution of sodium dodecylbenzenesulfonate dissolved in 500 ml of the high-speed stirring type dispersing machine 1 were added, and then heated to 35 ° C. A solution of the copolymer dissolved in advance was added thereto, and the mixture was stirred at a speed of 5,000 rpm for 15 minutes to obtain 225 g of a polymer oil droplet dispersion. When converted into polymer solid particle diameters, the polymer oil droplets had an average particle diameter d of 2 μm, a standard deviation σ of 1 μm, and a monodispersity σ / d of 0.5. In this case, the minimum weight of water to be added is [(solvent weight / solubility) − (weight of H ₂ O in dispersion)] = [(20 + 20) / 0.
075 × 0.5-150] = 117 g, and the maximum weight is calculated as (20 × dispersion weight) = 20 × 225 = 4500 g. Therefore, 400 g of water is put into the water tank 3 having an inner volume of 1,
Static mixer 5 with 24 elements by pumps 2 and 4 at a mixing ratio of water / dispersion of 400/225 = 1.78
To obtain an aqueous dispersion of a matting agent from the static mixer 5. The matting agent in this aqueous dispersion has an average particle size d of 2 μm, a standard deviation σ of 1 μm, and a monodispersity σ / d of 0.
5, which was consistent with the polymer oil droplet size (converted to the solid particle size). Thereafter, the dispersion of the matting agent was dried under reduced pressure at 45 ° C. and 100 mmHg to remove the solvent. [Comparative Example 1] 225 g of a polymer oil droplet dispersion obtained in the same manner as in Example 1 was used.
The mixture was placed in a 500 ml three-necked flask, and dried under reduced pressure at 45 ° C. and 100 mmHg to remove the solvent, thereby obtaining an aqueous dispersion of a matting agent. The matting agent in this aqueous dispersion has an average particle size d of 3 μm.
m, the standard deviation σ is 2μ, the monodispersity σ / d is 0.7, the average particle size is large, and the distribution is wide.

[Brief description of the drawings]

1 and 2 are schematic views showing an embodiment of the apparatus for producing polymer fine particles according to the present invention. 1 ... disperser, 2 ... pump, 3 ... water tank, 4 ...
... pump, 5 ... continuous mixer, 6 ... disperser, 7 ... continuous mixer.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08J 3/00-3/28 G03C 1/32

Claims (1)

(57) [Claims] 1. The method according to claim 1, which corresponds to the particle diameter of the polymer oil droplet immediately after dispersion.
An apparatus for producing polymer fine particles having an average particle size of 0.5 to 5 μm, wherein a polymer dissolved in an organic solvent having a solubility in water of 8 × 10 ^{−3 to} 3.3 × 10 ⁻¹ (g / gH ₂ O) is prepared. A polymer oil droplet generating means for generating polymer oil droplets by dispersing in water; [(weight of the organic solvent / solubility of the organic solvent in water) × 0.5− (amount of water already existing)] or more Water mixing means for mixing water up to 20 times the weight of the dispersion with the dispersion obtained by the polymer oil droplet generation means. .