JPH09176514A - Organic pigment having modified surface and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve dispersion stability an organic stability in an aqueous medium. SOLUTION: A polar gas to be bonded to fluorine to form a hydrophilic group is adsorbed on the surface of a pigment and the pigment is brought into contact with a fluorine gas. In this case, preferably the polar gas and the fluorine gas are diluted with an inert gas and used. If necessary, after the pigment is treated with the fluorine gas, an acidic component formed on the surface of the pigment particle is removed and neutralized.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a surface-modified organic pigment and a method for producing the same, and more particularly to a surface-modified organic pigment having excellent dispersibility and a method for producing the same. The surface-modified organic pigment of the present invention is a printing ink, a writing ink, a paint, a recording material,
It is particularly useful as a cosmetic, a pigment resin printing agent, and the like.

[0002]

2. Description of the Related Art Organic pigments are used as printing inks, writing inks, paints in general, recording materials, cosmetics, and colorants for textile printing agents. It is distinguished from dyes in that it is insoluble or sparingly soluble in water and organic solvents. For example, it is used by being dispersed in an aqueous solution containing boil oil or other drying oils in oil-based paints and adhesives in water-based inks. These drying oils and aqueous solutions that retain the pigment are called vehicles or color spreaders.

The properties of pigment-containing products are highly dependent on the dispersibility of the pigment particles in the vehicle. But,
Since the surface of an organic pigment is generally inferior in hydrophilicity, it is difficult to maintain long-term dispersion stability with water-based inks and water-based paints. As a result, the writing instrument may cause clogging,
There is a problem that the pigment in the paint is aggregated and settled to cause color unevenness. In order to solve this problem, it is considered important to improve the hydrophilicity of the pigment particle surface.

The following methods have been conventionally proposed as methods for imparting hydrophilicity to the surface of a pigment. For example, JP-A-6-8
In 0901, the pigment is treated with fluorine gas to improve the dispersibility. However, organic pigments have various functional groups and unsaturated bonds as chromophores. Therefore, when the fluorine gas, which is originally highly reactive, comes into contact with the surface of the pigment particles, a C—F covalent bond is formed depending on the type of the pigment compound to lower the hydrophilicity, or it is a strong electron withdrawing group. There is a problem that the hue of the pigment is changed because the fluorine atom is directly bonded. Further, since the treatment with fluorine gas progresses rapidly, the fluorination reaction proceeds excessively in the vicinity of the introduction portion of the fluorine gas, and when it is remarkable, a decomposition reaction occurs and carbon or tar that causes discoloration occurs,
On the other hand, there are cases where substantially unreacted particles that do not sufficiently modify the surface of the pigment remain in the portion away from the harm-introducing portion.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a simple and uniform hydrophilic property over the entire pigment powder to be treated, without impairing the original properties of the pigment such as hue, light resistance and weather resistance. Provided is a surface treatment method to be applied. Another object of the present invention is to provide a surface-modified organic pigment produced by such a treatment method and having excellent properties such as dispersibility.

[0006]

According to the present invention, a polar molecule that induces a hydrophilic group is attached to the surface of an organic pigment in advance and then treated with fluorine gas to reduce the adsorption of fluorine gas and impair the color developability of the pigment. Without improving the hydrophilicity, the dispersion stability of the organic pigment is remarkably enhanced.

That is, according to the present invention, the following surface-modified organic pigment and a method for producing the same are provided. (1) A surface-modified organic pigment characterized in that the pigment is brought into contact with a polar gas to adsorb the polar gas on the surface of the pigment, and then the surface is treated with a fluorine gas. (2) A method for producing a surface-modified organic pigment, which comprises contacting a pigment with a polar gas to adsorb the polar gas on the surface of the pigment, and then performing surface treatment with a fluorine gas. (3) A pigment is brought into contact with a polar gas diluted to 25 to 100 vol% with an inert gas to adsorb the polar gas on the surface of the pigment particles, and then the pigment is diluted to 0.01 to 30 vol% with fluorine gas. The method for producing a surface-modified organic pigment according to (2) above, which comprises contacting. (4) Adsorption of polar gas at −80 to 50 ° C.
The method for producing the surface-modified organic pigment according to (2) or (3). (5) The method for producing a surface-modified organic pigment according to any one of (2) to (4) above, wherein the treatment with fluorine gas is performed at -80 to 300 ° C. (6) The surface according to any one of (2) to (5) above, wherein the polar gas is a compound having a group that forms a hydrophilic group containing at least one element of C, S and N and O. Method for producing modified organic pigment. (7) The production method according to (6) above, wherein after the treatment with the fluorine gas, the acidic component remaining on the surface of the pigment is volatilized or neutralized to be removed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing an organic pigment of the present invention comprises:
The particle surface generated in the second step, which has a first step of adsorbing a polar gas on the surface of the pigment particles, and a second step of further treating the pigment obtained in the first step with fluorine gas. It further comprises a third step of neutralizing or removing the acidic component of.

(I) First Step (Adsorption of Polar Gas) In this treatment step, the pigment is brought into contact with the polar gas to adsorb the polar gas on the surface of the pigment. The polar gas used in this step refers to a compound (generally a polar compound) that is a gas around normal temperature and forms a hydrophilic group by bonding with fluorine. As such a compound, a compound containing at least one element of C, S, and N and O as constituent elements is suitable. Specific examples of the polar gas include CO, CO ₂ , SO ₂ , NO _{2 and the} like. Although the mechanism for making NO ₂ hydrophilic is unknown, it is included in the polar gas in the present invention because the same effect can be obtained.

In this treatment step, it is important that the polar gas is uniformly adsorbed on the entire surface of the pigment powder. Therefore, the treatment temperature in this step is suitably -80 ° C to 50 ° C, preferably -30 ° C to 40 ° C, and more preferably -20 ° C to 30 ° C. Processing temperature is 50
If the temperature is higher than ° C, the amount of polar gas adsorbed may decrease, and the effect of alleviating the adsorption of fluorine gas may become insufficient. -80
It is economically unfavorable to cool to below ℃.

By using a polar gas diluted with an inert gas, the adsorption amount on the pigment surface can be effectively controlled, and the polar gas can be uniformly adsorbed on the pigment surface. In this case, the concentration of polar gas is 25-100 vol%,
It is preferably 30 vol% or more, more preferably 35 vol% or more. If the concentration of the polar gas is less than 25 vol%, the amount adsorbed on the surface of the pigment will be small and a sufficient treatment effect cannot be obtained. The type of inert gas is not particularly limited, and may be nitrogen, argon, helium, carbon tetrafluoride, or the like.

The treatment time with the polar gas differs depending on the amount of the pigment and the concentration of the inert gas, but it suffices that the concentration of the polar gas after the contact treatment with the pigment reaches an equilibrium. Alternatively, the adsorption amount may be set in advance, and the introduction of the polar gas may be terminated when the adsorption amount is reached. Further, the adsorption of the polar gas may be performed by either a batch method in which a fixed amount of gas is charged or a continuous method in which the polar gas is continuously flowed. Further, it may be carried out by a method of flowing a pigment down in a gas. When the polar gas is adsorbed by these methods, pretreatment is not necessary, but it is preferable to introduce the polar gas after removing the adsorbate on the surface of the organic pigment and the gas in the container by preheating or depressurizing. .

(II) Second Step (Adsorption of Fluorine Gas) In this treatment step, the pigment having a polar gas attached to the surface is brought into contact with the fluorine gas for surface treatment. In order to obtain the hydrophilic surface effect, the treatment temperature in this step is suitably -80 ° C to 300 ° C, preferably -30 ° C to 150 ° C, more preferably -20 ° C to 150 ° C. Fluorine gas is highly reactive, so if the treatment temperature is higher than 300 ° C., even if the contact time and the flow rate of fluorine gas are suppressed, the organic pigment deteriorates and discolors, and the adsorption of fluorine gas tends to be non-uniform. It is economically unfavorable to cool it to -80 ° C or lower. By controlling the temperature, fluorine gas concentration, and contact time in this step, the required amount of fluorine can be firmly bonded to the substrate.

Also with respect to fluorine gas, the amount adsorbed on the pigment surface is controlled by diluting with an inert gas,
It can be adsorbed uniformly on the particle surface. The fluorine gas concentration is preferably 0.01 to 30 vol% and 0.1 to 10 vol%
Is more preferred. If the concentration of fluorine gas is less than 0.01 vol%, the amount of fluorine gas adsorbed is small and a sufficient effect cannot be obtained. On the other hand, when the fluorine gas concentration exceeds 30 vol%, the reaction of the fluorine gas is so vigorous that the pigment is deteriorated or discolored or the fluorine gas is not adsorbed uniformly. The type of fluorine gas may be nitrogen, argon, helium or the like as in the first step.

The surface modification with fluorine gas may be carried out by either a batch method in which a fixed amount of gas is charged or a continuous method in which a gas is continuously supplied for a fixed time. Alternatively, it may be carried out by a method of flowing a pigment down into a gas. The treatment time is appropriately adjusted with respect to the concentration of fluorine gas, the introduction amount, and the treatment temperature so that the surface modification of the pigment proceeds uniformly. Generally, depending on the type and amount of organic pigment, the amount of gas introduced, the shape of the device, etc., the amount of fluorine introduced should be 0.01 to 6 mmol / g in terms of the amount of fluorine / organic pigment. Adjust the reaction time. If this value is less than 0.01 mmol / g, there is no effect and 6 m
If it exceeds mol / g, the amount of fluorine adsorbed becomes excessive, which causes deterioration and discoloration of the pigment.

The first step and the second step may be carried out in the same container, and after the completion of the first step, the pigment treated with the polar gas is placed in another reaction vessel having a corrosion resistance to fluorine gas. You may transfer and may perform a 2nd process. Second in the same container
When carrying out the process, the polar gas remaining in the container reacts with the fluorine gas to consume the fluorine gas, and the heat generated at that time does not cause deterioration of the pigment. After the treatment, it is preferable to ventilate the residual gas or introduce an inert gas to replace or dilute the residual gas inside the container after the treatment.

Although the reaction on the pigment particle surface is not always clear, basically, in the first step, polar gas is adsorbed on the particle surface to cover the surface, and the fluorine gas introduced in the second step is introduced into the particle surface. reacts with the polar gas, -SO ₂ F in the surface of the pigment particles according to the type of polar gases, -SO
_It is considered that hydrophilic groups such as ₃ H, —COF, and —COOH are formed, and these hydrophilic groups chemically bond to the surface of the organic pigment. As a result, a surface-modified organic pigment that does not impair the color tone and is excellent in dispersibility can be obtained. In particular, since the proportion of fluorine gas that directly reacts with the surface of the organic pigment is extremely low, the surface modification treatment is performed uniformly,
It is possible to obtain an organic pigment having excellent properties as compared with the case where the surface treatment is performed with fluorine alone.

If the first step is omitted, the adsorption of fluorine gas proceeds excessively, the amount of organic pigments that have changed to black increases, and the surface treatment becomes non-uniform, so that the hue uniformity, hydrophilicity and dispersibility are improved. breaking bad. The blackening of the pigment is considered to be caused by carbon or tar generated as a result of excessive reaction between the organic pigment and the fluorine gas. In the conventional surface treatment method, it is known that the treatment with fluorine gas is performed in the air, but the treatment effect by the polar gas in the first step can be quite achieved at a concentration of O ₂ or CO _{2 in} the air. I can't.

In both the first step and the second step, it is preferable to uniformly treat the organic pigment, prevent agglomeration, or agitate or shake during the treatment step in order to control the particle size. As the stirring method, a fluidized bed type, stirring blade, ball mill, or the like can be widely used.

(III) Third Step (Neutralization Step) After the completion of the second step, if the acidic gas component remains on the surface of the pigment particles, it is volatilized or neutralized to be removed. The acidic gas component is unreacted polar gas or fluorine gas, or HF and various reaction products generated by the reaction of these, and if these remain on the pigment surface, when the pigment is used in a product. This is not preferable because it may impair the dispersion stability and cause corrosion.

When the acidic gas component is removed by volatilization, the treated pigment particles are heated in an inert gas, preferably in an inert gas stream, to 150 ° C. or lower, preferably 100 ° C. or lower. When the acidic gas component is neutralized, a basic gas such as ammonia gas is introduced into the pigment by entraining it in an inert gas, or treatment with water and an alkaline aqueous solution is appropriately performed. Usually, the base concentration may be low, although it depends on the remaining amount of acidic gas.

(IV) Others The types of organic pigments to which the present invention can be effectively applied are wide-ranging. As a pigment, anthraquinone type, indigo-thioindigo type, perinone type, perylene type, phthalone type,
Examples thereof include dioxazine type, quinacridone type, isoindolinone type, metal complex pigments, methine-azomethine type, diketopyrrolopyrrole type and the like. The pigments used in Examples and Comparative Examples are shown in Table 4.

In the surface modification method of the present invention, the radical adsorption of fluorine is suppressed and the surface modification of the pigment proceeds uniformly. As a result, almost no blackening of the pigment occurs, and the obtained surface-modified pigment has excellent dispersibility in an aqueous medium for a long period of time.
Therefore, the surface-modified pigment of the present invention can be widely used for not only oily products but also aqueous products. Specifically, letterpress ink, engraving intaglio ink, gravure ink, flexo ink, offset ink, screen ink, and other printing inks, paints, crayons, pastel, markers, felt-tip pens, ballpoint pens, and other writing inks, electrodeposition paints, cans. Applications such as paints for automobiles, paints for automobiles, recording materials for thermal transfer or ink jet printers, colorants for plastics, colorants for rubber, paper colorants, pigment resin printing agents, etc. are expected. To be done.

[0024]

EXAMPLES Examples of the present invention will be described below together with comparative examples.
In addition, the following examples do not limit the scope of the present invention. First, the evaluation methods of organic pigments in Examples and Comparative Examples are shown below.

(A) Dispersion test 1 0.2 g of the sample pigment (surface-modified pigment, untreated product) was placed in a colorimetric tube (diameter 24 mm, length 100 mm), 50 g of water was added, and the mixture was shaken and stirred, The sample was uniformly dispersed in water, and after 24 hours, the coloring state of the aqueous phase was visually observed, and the affinity of the organic pigment to the aqueous medium was determined based on the case where the untreated pigment was used as the sample. Judgment was made on the basis of the coloring state of the dispersion liquid, and was carried out in three stages: very dark (o in the table), dark (o in the table), and light (x in the table). Thickly colored ones have excellent dispersibility.

(B) Dispersion test 2 Sample pigment (surface-modified pigment, untreated product), water-soluble acrylic resin (John Cryl J-61: manufactured by Johnson Polymer), glass beads (1φ), dimethylaminoethanol (reagent) (Special grade: manufactured by Wako Pure Chemical Industries, Ltd.) and water are put in a mayonnaise bottle according to the following formulation, and shaken and stirred with a paint conditioner for 4 hours to uniformly disperse the sample in water to produce an aqueous ink. The obtained ink was placed in the same colorimetric tube as in Dispersion Test 1 and allowed to stand at 50 ° C. for 2 months, and the degree of sedimentation of the pigment was visually observed to determine the dispersion stability of the sample. The formulation example (parts by weight) of the water-based ink composition is sample pigment (5 parts), acrylic resin (15 parts), dimethylaminoethanol (4.5 parts),
Glass beads (30 parts) and water (45.5 parts). Judgment was based on the pigment precipitate used as a sample, and the precipitate was observed (marked with X in the table), and the pigment precipitate was not observed and the dispersion was colored (marked with ◎ in the table). It was judged in two stages.

(C) Dispersion test 3 0.2 g of the sample pigment (surface-modified pigment, untreated product) was placed in the same colorimetric tube as in the dispersion test 1, 50 g of water was added, and the mixture was shaken and stirred to make the sample in water. Evenly disperse After 24 hours, the amount of the organic pigment that changed to black and floated on the water interface (meniscus) was visually observed to determine the uniformity of the fluorination reaction. Judgment is based on the amount of the black alteration organic pigment that floats on the interface, and there is almost no (the ◎ mark in the table), a small amount (1 mm thickness or less,
Judgment was made in three stages: ○ in the table) and a large amount (1 to 10 mm thickness, x in the table).

Example 1 A surface modification treatment of a copper phthalocyanine blue pigment was carried out according to the following steps under the treatment conditions (SF-1 to SF-14) shown in Table 1. First step 50 g of copper phthalocyanine blue pigment (Lionol blue FG-7351: manufactured by Toyo Ink Co., Ltd.) is charged into a Teflon coating SUS reaction tube equipped with a stirrer, and the inside of the reaction tube is depressurized (1 Torr).
r) to remove air and other deposits from the treatment system,
The inside of the reaction tube was maintained at the temperature shown in the table, and a polar gas (SO ₂ , CO ₂ , CO, O ₂ , NO ₂ ) diluted with nitrogen gas to the concentration shown in the table was introduced. After reaching the adsorption equilibrium, nitrogen gas in an amount three times the reaction tube volume was flowed for 20 seconds to remove unadsorbed polar gas remaining in the reaction tube.

Second Step While stirring the pigment in the reaction tube, fluorine gas diluted with nitrogen gas was introduced into the reaction tube. During this period, the temperature inside the reaction tube was maintained at the temperature shown in the table. After the lapse of the treatment time in the table, nitrogen gas was introduced to replace the gas in the tube to stop the surface modification. Step 3 The inside of the reaction tube is heated to 50 ° C., nitrogen gas is filled into the reaction tube, and after the fluorine gas is no longer observed in the gas discharged, the surface-modified organic pigment is taken out and the dispersion test 1 to 3 was performed. The results are shown in Table 3.

Examples 2 to 14 The pigments were surface-treated in the same manner as in Example 1 except that the various pigments shown in Table 3 were used instead of the copper phthalocyanine blue pigment. These results are summarized in Table 3.

Comparative Examples 1 to 14 Conditions similar to those of Examples 1 to 14 except that the treatment with the polar gas in the first step was omitted and only the treatment with the fluorine gas in the second step was performed according to the conditions in Table 2. The surface treatment of the pigment was carried out. The results of the dispersion test are summarized in Table 3.

Comparative Examples 1B-14B As a control for comparing the dispersion effects of the above Examples 1-14 and Comparative Examples 1-14, the pigments used in the Examples and Comparative Examples were not surface-treated and their respective dispersibility was determined. Was tested. The results are summarized in Table 3.

[0033]

[0034]

[0035]

[0036]

As is clear from these results, when only the conventional fluorine gas treatment was performed (Comparative Examples 1 to 1)
4), the dispersibility in the aqueous medium is moderate, but the dispersibility in the aqueous ink is poor, and a small amount to a large amount of pigment blackening is observed in all of these comparative examples. on the other hand,
The organic pigment, which has been subjected to the adsorption of polar gas and the treatment with fluorine gas in order according to the method of the present invention, has excellent hydrophilicity (dispersion test 1), and exhibits high dispersion stability even when used in aqueous ink and the like. Do (dispersion test 2). Moreover, almost no black discoloration of the pigment was generated, and excessive fluorination was suppressed (dispersion test 3). It is considered that the chemical reaction at the time of the fluorine treatment is relaxed by the polar gas previously adsorbed on the surface of the pigment and uniformly proceeds on the entire surface of the pigment.

[0038]

EFFECT OF THE INVENTION In the conventional surface treatment with fluorine gas, the treatment of the organic pigment is non-uniform and an excessive reaction locally proceeds, so that there is a problem in dispersion stability when it is commercialized as an aqueous ink. However, the manufacturing method of the present invention, as a result of combining the treatment with the polar gas and the treatment with the fluorine gas,
The pigment particles are uniformly modified over the entire surface and have excellent dispersion stability even when they are commercialized, and since excessive fluorination is suppressed, there is almost no blackening of the pigment, and Problems such as residual unreacted pigment are eliminated.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kota Omori Inventor Kota 3-6, Ibaraki, Akita City, Akita Prefecture In Tochem Products Co., Ltd. Toyo Inki Manufacturing Co., Ltd. (72) Inventor Shuji Miyazaki 2-3-13 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd.

Claims (7)

[Claims] 1. A surface-modified organic pigment, characterized in that the pigment is brought into contact with a polar gas to adsorb the polar gas on the surface of the pigment and then surface-treated with a fluorine gas. 2. A method for producing a surface-modified organic pigment, which comprises contacting a pigment with a polar gas to adsorb the polar gas on the surface of the pigment, and then surface-treating the surface with a fluorine gas. 3. A polar gas diluted to 25 to 100 vol% with an inert gas is brought into contact with the pigment to adsorb the polar gas on the surface of the pigment particles, and then the pigment is diluted to 0.01 to 30 vol% with fluorine. The method for producing a surface-modified organic pigment according to claim 2, wherein the surface-modified organic pigment is brought into contact with a gas. 4. The method for producing a surface-modified organic pigment according to claim 2, wherein the adsorption of the polar gas is performed at −80 to 50 ° C. 5. The treatment with fluorine gas is -80 to 300.
The method for producing a surface-modified organic pigment according to any one of claims 2 to 4, which is carried out at a temperature of ° C. 6. The surface modification according to claim 2, wherein the polar gas is a compound having a group forming a hydrophilic group containing at least one element of C, S and N and O. Of producing high quality organic pigment. 7. The method according to claim 6, wherein after the treatment with the fluorine gas, the acidic component remaining on the surface of the pigment is removed by volatilization or neutralization.