JP6013244B2 - Carbon black composition and coating film containing carbon black - Google Patents

Description

The present invention relates to a carbon black composition, and more particularly to a carbon black composition that can realize a highly dispersed state of carbon black in a solvent.
Furthermore, this invention relates also to the carbon black containing coating film obtained from the said carbon black composition.

  Carbon black is used in various fields such as printing inks, paints, cosmetics, and batteries as coloring materials, conductive materials, fillers, and the like. In the magnetic recording field, carbon black may be added to the magnetic layer, nonmagnetic layer, back coat layer, etc. to prevent charging of magnetic tapes and magnetic disks, reduce friction coefficient, impart light shielding properties, and improve film strength. Widely done.

  As mentioned above, carbon black is a useful material used in various fields, but it has the property of forming and aggregating higher-order structures called structures in a solvent. Bring. For example, in a coating-type magnetic recording medium, when carbon black aggregates in a coating solution, the smoothness of a coating film such as a magnetic layer formed by coating and drying the coating solution on a support is greatly reduced. Become. In addition, when carbon black aggregates in the printing ink, it causes color unevenness and color tone deterioration in printed matter using this ink.

  Therefore, conventionally, attempts have been made to improve the dispersibility of carbon black in a solvent (see, for example, Patent Document 1).

JP 2001-344738 A

  As described above, carbon black is widely used in various fields, and improvement in its dispersibility (prevention of aggregation) is always required. On the other hand, Patent Document 1 proposes enhancing the dispersibility of carbon black by using an amine compound. However, the carbon black dispersion technique described in Patent Document 1 is required to be further improved in terms of the storage stability of the carbon black dispersion, as will be described later.

  Under such circumstances, the present invention was made for the purpose of providing a composition (carbon black composition) excellent in preservability in which carbon black is highly dispersed in a solvent.

As described above, the carbon black dispersion technique described in Patent Document 1 has a problem in terms of storage stability of the carbon black dispersion.
To further explain this point, Patent Document 1 proposes a carbon black dispersion technique using a bifunctional amine as a dispersant. However, the amino group contained in the amine is a solvent used in the carbon black dispersion or a functional group contained in the binder resin that is a component that can be used together (for example, a ketone group in a ketone solvent, a urethane in a polyurethane). There is a concern that the storage stability of the carbon black dispersion may be reduced by a side reaction such as a reaction with a group.

On the other hand, as a result of intensive studies, the present inventors have newly found that the above object can be achieved by a hydroxyl group-containing tertiary diamine compound represented by the following general formula (I).
The present inventor presumes the reason why both the dispersibility improvement of carbon black and the storage stability of the dispersion can be achieved by the hydroxyl group-containing tertiary diamine compound represented by the general formula (I) as follows. .
(1) Since tertiary amines are stable with respect to various functional groups, tertiary diamine compounds represented by the general formula (I) are similar to primary or secondary alkylamines or alkoxyamines having a similar structure. In comparison, there is less concern about side reactions with components used in combination such as solvents and binder resins. The hydroxyl group is also stable against various functional groups. This is considered to contribute to good storage stability.
(2) The hydroxyl group-containing diamine compound represented by the general formula (I) includes a hydroxyl group that contributes to improving the storage stability of the carbon black composition as described above, in only one of the two amino groups, and not in the other. . Since this amino group not containing a hydroxyl group is excellent in affinity with carbon black, the diamine compound can exhibit high adsorptivity to carbon black. This is considered to contribute to the improvement of dispersibility by inhibiting the formation of the carbon black structure. Although the hydroxyl group has poor affinity with carbon black, the diamine compound represented by the general formula (I) has a hydroxyl group that is localized only in one of the two amino groups. It is considered that the hydroxyl group can contribute to the improvement in storage stability of the carbon black composition without hindering the improvement.
The present invention has been completed based on the above findings.

That is, the above object has been achieved by the following means.
[1] A carbon black composition comprising carbon black and a hydroxyl group-containing diamine compound represented by the following general formula (I) in a solvent.
[In General Formula (I), R ¹ represents an alkyl group having 3 to 21 carbon atoms, an alkoxyalkyl group having 5 to 25 carbon atoms, an arylalkyl group, or an aryloxyalkyl group, and two R ^{1 s} are different from each other. Or at least one R ¹ includes a hydroxyl group as a substituent; R ² represents an alkyl group or a cycloalkyl group that may be bonded to a nitrogen atom via a linking group; The two R ^{2 s} may be different or the same, provided that neither of the two R ² contains a hydroxyl group; L represents an alkylene group. ]
[2] The carbon black composition according to [1], wherein the total number of hydroxyl groups contained in two R ¹ in the general formula (I) is 2 or more.
[3] The carbon black composition according to [1] or [2], wherein two R ^{1 s} in the general formula (I) each contain one or more hydroxyl groups.
[4] The carbon black according to any one of [1] to [3], wherein the hydroxyl group-containing diamine compound represented by the general formula (I) is a hydroxyl group-containing diamine compound represented by the following formula (II): Composition.
[In General Formula (II), X represents a hydroxyl group-containing alkylene group, and the group represented by -XY is synonymous with the group represented by R ¹ in General Formula (I), and two X, Y may be different or the same, and R ² and L have the same meaning as in general formula (I). ]
[5] The carbon black according to any one of [1] to [4], wherein the hydroxyl group-containing diamine compound represented by the general formula (I) is a hydroxyl group-containing diamine compound represented by the following general formula (III): Composition.
[In general formula (III), Z is a substituent which forms a group represented by R ¹ in general formula (I) together with linking —CH (OH) CH ₂ —, and the two Zs are different from each other. Or R ² and L are as defined in general formula (I). ]
[6] The carbon black according to any one of [1] to [5], wherein the hydroxyl group-containing diamine compound represented by the general formula (I) is a hydroxyl group-containing diamine compound represented by the following formula (IV): Composition.
[In general formula (IV), Z is a substituent which forms a group represented by R ¹ in general formula (I) together with linking —CH (OH) CH ₂ —, and the two Zs are different from each other. Or R ² has the same meaning as in formula (I). ]
[7] The carbon black composition according to any one of [1] to [6], further including a binder resin.
[8] The carbon black composition according to [7], wherein the binder resin is selected from the group consisting of a vinyl copolymer and a polyurethane resin.
[9] The carbon black composition according to any one of [1] to [8], further comprising a polyisocyanate compound.
[10] The carbon black composition according to any one of [1] to [9], wherein the solvent includes a ketone solvent.
[11] A carbon black-containing coating film formed by drying the carbon black composition according to any one of [1] to [10].
[12] The carbon black-containing coating film according to [11], which is formed by performing a heat treatment after the drying.

  According to the present invention, a carbon black composition in which carbon black is highly dispersed in a solvent can be provided. Further, by using the carbon black composition of the present invention, a carbon black coating film having excellent surface smoothness can be provided because carbon black is highly dispersed. Such a carbon black composition of the present invention is useful as a printing ink, a coating liquid for a coating type magnetic recording medium, and the like.

The carbon black composition of the present invention contains a hydroxyl group-containing diamine compound represented by the general formula (I) described in detail below in a solvent. The carbon black composition of the present invention can contain carbon black in a highly dispersed state and can exhibit good storage stability. The inventor's inference regarding these points is as described above.
Hereinafter, the carbon black composition of the present invention will be described in more detail. In the following description, the “carbon number” in the case of having a substituent means the carbon number of a portion not including the substituent. As the following substituents, for example, an alkyl group (for example, an alkyl group having 1 to 6 carbon atoms), an alkoxyl group (for example, an alkoxyl group having 1 to 6 carbon atoms), a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom), A cyano group, an amino group, a nitro group, an acyl group, a carboxyl group, etc. can be mentioned. Further, in the present invention, “to” indicates a range including numerical values described before and after that as a minimum value and a maximum value, respectively.

Carbon black The carbon black contained in the carbon black composition of the present invention is not particularly limited, and various carbon blacks such as furnace for rubber, thermal for rubber, black for color, conductive carbon black, acetylene black, etc. It can be selected and used according to the application. Regarding the carbon black that can be used in the present invention, for example, “Carbon Black Handbook” (edited by the Carbon Black Association) can be referred to.

For example, in a coating type magnetic recording medium, carbon black can be mixed with a nonmagnetic layer to reduce the surface electrical resistance Rs, which is a known effect, to reduce the light transmittance, and to obtain a desired micro Vickers hardness. In addition, it is possible to bring about the effect of storing the lubricant by including carbon black in the nonmagnetic layer. The specific surface area of the carbon black used for the nonmagnetic layer is usually 50 to 500 m ² / g, preferably 70 to 400 m ² / g, and the DBP oil absorption is usually 20 to 400 ml / 100 g, preferably 30 to 400 ml / 100 g. It is. The average primary particle diameter of carbon black used for the nonmagnetic layer is usually 5 to 80 nm, preferably 10 to 50 nm, and more preferably 10 to 40 nm.

Further, by adding fine carbon black to the backcoat layer of the coating type magnetic recording medium, the surface electrical resistance of the backcoat layer can be set low, and the light transmittance can also be set low. Some magnetic recording devices utilize the light transmittance of the tape and are used for the operation signal. In such a case, the addition of particulate carbon black is particularly effective. The fine particle carbon black used for the back coat layer has an average primary particle diameter in the range of 5 to 30 nm, a specific surface area in the range of 60 to 800 m ² / g, and a DBP oil absorption of 50 to 130 ml / 100 g. It is in the range and the pH is in the range of 2-11.

  For details of the carbon black, reference can be made, for example, to paragraphs [0033] and [0053] of Japanese Patent No. 4149648.

  The carbon black composition of the present invention can also be used for forming a magnetic layer of a coating type magnetic recording medium. For details of carbon black contained in the magnetic layer, reference can be made to paragraph [0067] of Japanese Patent No. 4149648.

The carbon black composition of the present invention comprises the above-described carbon black together with a hydroxyl group-containing diamine compound represented by the general formula (I) and a solvent, and optionally added various components, for forming a coating type magnetic recording medium. It can be used as a coating composition or for the preparation of the coating composition. For example, by using the carbon black composition of the present invention as a coating composition for forming a non-magnetic layer or a back coat layer of a coating type magnetic recording medium or for the preparation of the coating composition, A coating type magnetic recording medium having a nonmagnetic layer, a backcoat layer, and a magnetic layer dispersed in the film can be obtained.
The carbon black is also preferably used as a pigment for printing ink, and the carbon black composition of the present invention containing the carbon black is used for various printing methods such as inkjet printing, offset printing, and gravure printing. It can be suitably used as a black ink.

Hydroxyl-containing diamine compound Next, the hydroxyl-containing diamine compound represented by the general formula (I) contained in the carbon black composition of the present invention together with carbon black and a solvent will be described.

[In General Formula (I), R ¹ represents an alkyl group having 3 to 21 carbon atoms, an alkoxyalkyl group having 5 to 25 carbon atoms, an arylalkyl group, or an aryloxyalkyl group, and two R ^{1 s} are different from each other. Or at least one R ¹ includes a hydroxyl group as a substituent; R ² represents an alkyl group or a cycloalkyl group that may be bonded to a nitrogen atom via a linking group; The two R ^{2 s} may be different or the same, provided that neither of the two R ² contains a hydroxyl group; L represents an alkylene group. ]

In general formula (I), R ¹ represents an alkyl group having 3 to 21 carbon atoms, an alkoxyalkyl group having 5 to 25 carbon atoms, an arylalkyl group, or an aryloxyalkyl group.

The alkyl group represented by R ¹ is a linear or branched alkyl group. The carbon number is 3 or more from the viewpoint of improving dispersibility, and 21 or less from the viewpoint of solvent solubility. The carbon number is preferably in the range of 3 to 18, more preferably 3 to 8.

The alkoxyalkyl group represented by R ¹ is represented by R′OR—, and the number of carbon atoms of the main chain alkylene group represented by R and the alkyl group represented by R ′ linked thereto via an oxygen atom. Is 5 or more from the viewpoint of improving dispersibility, and 25 or less from the viewpoint of solvent solubility. The carbon number is preferably in the range of 5 to 18, more preferably 5 to 10.

The arylalkyl group represented by R ¹ is represented by ArR-, and the total number of carbon atoms of the main chain alkylene group represented by R and the aryl group represented by Ar connected thereto is improved in dispersibility. From the viewpoint, it is preferably 8 or more, and from the viewpoint of solvent solubility, it is preferably 14 or less. The aryl group is more preferably a phenyl group, a naphthyl group, or a biphenyl group, and even more preferably a phenyl group.

The aryloxyalkyl group represented by R ¹ is represented by ArOR-, and the total number of carbon atoms of the main chain alkylene group represented by R and the aryl group represented by Ar linked thereto via an oxygen atom. Is preferably 9 or more from the viewpoint of improving dispersibility, and is preferably 15 or less from the viewpoint of solvent solubility. The aryloxyalkyl group is more preferably a phenyloxymethylene group, a naphthyloxymethylene group, or a biphenyloxymethylene group, and more preferably a phenyloxymethylene group.

The alkyl group, alkylene group, and aryl group contained in the group represented by R ¹ described above may be unsubstituted or may have a substituent.

The number of carbon atoms of the aryl group contained in the arylalkyl group and aryloxyalkyl group represented by R ¹ is preferably 6-20, more preferably 6-10, and even more preferably 6. From the viewpoint of reactivity with the polyisocyanate compound described later, the aryl group is preferably unsubstituted and more preferably an unsubstituted phenyl group.

  From the viewpoint of further improving dispersibility, the total number of carbon atoms per molecule of the diamine compound represented by the general formula (I) is preferably 13 or more, more preferably 15 or more, for example 15 A range of ˜30 is preferred.

In the diamine compound represented by the general formula (I), two R ^{1 s} may be different or the same. However, at least one R ¹ contains a hydroxyl group as a substituent. As described above, it is possible to provide a carbon black composition having excellent storage stability by containing a hydroxyl group.

The diamine compound represented by the general formula (I) may contain a hydroxyl group at the terminal of the group represented by R ¹ or may be contained in the side chain. From the viewpoint of improving the storage stability of the carbon black composition, the dispersant contained in the composition is preferably low in volatility. Therefore, the diamine compound represented by the general formula (I) preferably has a high boiling point. From the viewpoint of increasing the boiling point, the hydroxyl group is preferably contained as a substituent in the side chain of the group represented by R ¹ . In addition, when the group represented by R ¹ is an arylalkyl group or an aryloxyalkyl group, the hydroxyl group is not included in the terminal aryl group but is included in the side chain. It is preferable from the viewpoint of reactivity.
The group represented by R ¹ has at least one hydroxyl group, and from the viewpoint of increasing the boiling point, it is preferably 2 or more, for example, 2 to 4, and more preferably 2. Moreover, the fact that two or more hydroxyl groups are contained in the diamine compound means that a higher-strength coating film can be formed by continuously proceeding with a reaction (crosslinking reaction) with a polyisocyanate described later. Is also preferable.

The hydroxyl group may be contained only in ^one of the groups represented by R ^{1 or} may be contained in both. From the viewpoint of ease of synthesis, it is preferable that two R ^{1 s} each contain one or more hydroxyl groups.

Therefore, as a preferred embodiment of the hydroxyl group-containing diamine compound represented by the general formula (I), a hydroxyl group-containing diamine compound represented by the following formula (II), which contains a hydroxyl group in each of the two R ¹ side chains, is exemplified. be able to.

In general formula (II), X represents a hydroxyl group-containing alkylene group, the group represented by -XY is synonymous with the group represented by R ¹ in general formula (I), and R ² and L are These are synonymous with the general formula (I).

Further, among the hydroxyl group-containing diamine compounds represented by the general formula (I), for example, as a compound obtained by a reaction using oxirane described later, R ¹ in the general formula (I) is —CH (OH) CH Examples thereof include a hydroxyl group-containing diamine compound represented by the following general formula (III), which is linked to a nitrogen atom by _2- .

In the general formula (III), Z is a substituent which forms a group represented by R ¹ in the general formula (I) together with linking —CH (OH) CH ₂ —, and the two Zs are different from each other. And R ² and L each have the same meaning as in general formula (I).

Next, L and R ² in the general formula (I) will be described.

  In general formula (I), L represents an alkylene group. The number of carbon atoms of the alkylene group represented by L is preferably 2 or more from the viewpoint of dispersibility of carbon black, preferably 20 or less from the viewpoint of solvent solubility of the compound, More preferably, the range is 2, and even more preferably 2. The alkylene group represented by L may be linear or branched, but is preferably linear.

  Therefore, as a preferred embodiment of the general formula (III) described above, a hydroxyl group-containing diamine compound represented by the following general formula (IV) in which the linking group represented by L is an ethylene group having 2 carbon atoms can be exemplified. .

In the general formula (IV), Z has the same meaning as the general formula (III), R ² has the same meaning as in formula (I).

R ² represents an alkyl group or a cycloalkyl group that may be bonded to the nitrogen atom via a linking group. As the alkyl group, those having 1 to 10 carbon atoms are preferable, those having 1 to 5 carbon atoms are more preferable, and those having 1 to 4 carbon atoms are more preferable from the viewpoint of achieving both the adsorptivity to carbon black and the solvent solubility of the compound. . The alkyl group may be linear or branched, but is preferably linear. On the other hand, the cycloalkyl group is preferably one having 6 to 10 carbon atoms from the same viewpoint. The linking group is not particularly limited, and examples thereof include an alkylene group. The details of the alkylene group are as described above for the alkylene group represented by L.

In general formula (I), two R ^{2 s} may be different or the same. However, as described above, since the hydroxyl group is poor in affinity with carbon black, both of the ^two R2s do not contain a hydroxyl group.

  Specific examples of the hydroxyl group-containing diamine compound represented by the general formula (I) described above include the compounds shown in the examples described later.

  The method for synthesizing the hydroxyl group-containing diamine compound represented by the general formula (I) is not particularly limited. As an example, a method utilizing a reaction between a cyclic ether and a primary amino group can be mentioned.

In the above reaction, the synthesis raw material to be reacted with the cyclic ether is a diamine compound having a primary amino group NH ₂ — in the hydroxyl group-containing amino group in the compound represented by the general formula (I) which is the target compound. The diamine compound can be synthesized by a known method, and is also available as a commercial product.

The cyclic ether is opened, and one or both of the two hydrogen atoms of the primary amino group of the ring-opened product and the synthetic diamine compound react with each other to thereby form two R ^{1 in} the general formula (I). The target diamine compound having a hydroxyl group on one or both can be obtained. What is necessary is just to select the cyclic ether to be used according to the structure of the target diamine compound. From the viewpoint of reaction efficiency, it is preferable to use oxirane (three-membered cyclic ether) as the cyclic ether.

The atmosphere in which the reaction is performed is not particularly limited, and the reaction can be favorably progressed, for example, in air or under nitrogen. As the reaction solvent, it is preferable to use a solvent that is stable with respect to the cyclic ether and the amino group and that can dissolve the cyclic ether and the diamine compound as a synthesis raw material. After completion of the reaction, the target diamine compound can be recovered by, for example, concentration to dryness. The cyclic ether, the diamine compound as a synthesis raw material, and the hydroxyl group-containing diamine compound represented by the general formula (I), which is a reaction product, are all usually liquid at room temperature and can be a solvent that dissolves each other. Therefore, the reaction can proceed even without solvent. A method in which the reaction is performed without a solvent is a more preferable method because the cyclic ether group and the primary amino group react at a high concentration, so that the reaction is fast and no waste is generated.
The reaction may be performed at room temperature or warmed. Heating is more desirable because the reaction proceeds faster. The heating is preferably performed so that the temperature of the reaction system is in the range of 40 ° C to 140 ° C. When the boiling points of the synthetic ether cyclic ether and diamine compound are in the range of 40 ° C. to 140 ° C., the reaction slows because the raw material volatilizes when reacted under high temperature conditions from the beginning. In such a case, it is desirable to gradually raise the temperature as the reaction proceeds.

  From the viewpoint of further improving the dispersibility of the carbon black, it is preferable to use the hydroxyl group-containing diamine compound represented by the general formula (I) at a ratio of 1 to 50 parts by mass with respect to 100 parts by mass of the carbon black. 1 to 20 parts by mass is more preferable. For the same reason, in the carbon black composition of the present invention, the total amount of the solvent with respect to the carbon black is preferably 100 to 5000 parts by mass with respect to 100 parts by mass of the carbon black. In the carbon black composition of the present invention, the hydroxyl group-containing diamine compound represented by the general formula (I) may be used singly or in combination of two or more.

The solvent contained in the carbon black composition of the present invention preferably contains a ketone solvent from the viewpoint of highly dispersing carbon black by using in combination with the hydroxyl group-containing diamine compound represented by the general formula (I). More preferably, the ketone solvent accounts for 50% by mass or more of the total amount of the solvent, and may be a 100% ketone solvent. Examples of the ketone solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone, and tetrahydrofuran. Examples of the solvent other than the ketone solvent include various solvents such as an alcohol solvent, an ether solvent, and an ester solvent. The said solvent may be used individually by 1 type, and may be used in combination of 2 or more type by arbitrary ratios.
Ketone solvents are generally readily available, and are easy to handle because of their relatively low boiling point and high safety. For this reason, ketone solvents are widely used in various fields such as the magnetic recording field, the printing field, and the cosmetic field. The carbon black composition of the present invention containing a ketone solvent as a solvent is useful in the various fields described above. Since the diamine compound represented by the general formula (I) contains a hydroxyl group that is stable with respect to various functional groups, there is little concern about a decrease in storage stability due to a side reaction with a ketone group contained in a ketone solvent. Thus, it is a compound suitable for combined use with a ketone solvent.

As a general method for improving the dispersibility of fine particles, a method of coating the surface of fine particles with a resin (binder) is known. The carbon black composition of the present invention contains a hydroxyl group represented by the general formula (I) By including a diamine compound, a highly dispersed state of carbon black can be realized without using a resin in combination. Specifically, the carbon black composition of the present invention has a carbon particle diameter of 150 nm or less, preferably 70 nm, more preferably 50 nm or less, measured in a dynamic light scattering method, for example, even in a state that does not contain a resin. A highly dispersed state of black can be realized.
Here, the particle diameter in liquid measured by the light scattering method is an indicator of the existence state of the carbon black in the carbon black composition of the present invention, that is, an indicator of the dispersion state. It means that it is well dispersed in a state close to primary particles. The measurement by the dynamic light scattering method can be performed using, for example, a dynamic light scattering particle size distribution measuring device LB-500 manufactured by HORRIBA. In order to increase the measurement accuracy, it is also possible to measure the particle size in the liquid after diluting the liquid to be measured. In this case, in order to further increase the measurement accuracy, it is preferable to use a solvent contained in the liquid to be measured as a dilution solvent, and it is more preferable to use the same solvent as the liquid to be measured.

  Moreover, carbon black composition of this invention can disperse | distribute carbon black still more highly by containing resin. By using the resin in combination, it becomes possible to disperse the carbon black in a very high dispersion state in which the particle diameter in the liquid is 70 nm or less, further 60 nm or less or 50 nm or less. Regardless of whether or not the resin is used, the lower limit value of the particle diameter in liquid is the primary particle diameter or the average primary particle diameter of carbon black.

  Usable resins include polyurethane resin, polyester resin, polyamide resin, vinyl chloride resin, acrylic resin copolymerized with styrene, acrylonitrile, methyl methacrylate, cellulose resin such as nitrocellulose, epoxy resin, phenoxy Examples thereof include polyvinyl alkyl resins such as resin, polyvinyl acetal, and polyvinyl butyral. Among them, use of a polyurethane resin and a vinyl copolymer is preferable. Resin can be used in the ratio of 1-100 mass parts with respect to 100 mass parts of carbon black, for example.

The carbon black composition of this invention can also contain an isocyanate compound with the said resin. The isocyanate compound is a component that contributes to improving the strength of the coating film by forming a crosslinked structure with the resin as a curing agent.
As the isocyanate compound, it is preferable to use a bifunctional or higher functional isocyanate compound (polyisocyanate). As an isocyanate compound, the well-known thing used as a hardening | curing agent, for example in a coating-type magnetic recording medium can be used in the quantity of 5-100 mass parts with respect to 100 mass parts of resin. For details of the isocyanate compound that can be used, reference can be made, for example, to paragraph [0066] of Japanese Patent No. 4149648.

  Furthermore, the carbon black composition of this invention can contain the well-known various additives used according to a use.

The average particle size of powder such as carbon black in the present invention can be measured by the following method.
The powder is photographed at a photographing magnification of 100,000 using a Hitachi transmission electron microscope H-9000, and is printed on a photographic paper so that the total magnification is 500,000 times to obtain a particle photograph. The target particle is selected from the particle photograph, the outline of the powder is traced with a digitizer, and the particle size is measured with the image analysis software KS-400 manufactured by Carl Zeiss. Measure the size of 500 particles. Let the average value of the particle size measured by the said method be an average particle size of the said sex powder.

In the present invention, the size of the powder (hereinafter referred to as “powder size”) is (1) the shape of the powder is needle-like, spindle-like, columnar (however, the height is larger than the maximum major axis of the bottom surface), etc. In this case, it is represented by the length of the long axis constituting the powder, that is, the length of the long axis. (2) The shape of the powder is plate or columnar (however, the thickness or height is the maximum of the plate surface or the bottom surface). (Smaller than the major axis), it is represented by the maximum major axis of the plate surface or bottom surface. (3) The shape of the powder is spherical, polyhedral, unspecified, etc., and the major axis constituting the powder from the shape If it cannot be specified, it is represented by the equivalent circle diameter. The equivalent circle diameter is a value obtained by a circle projection method. In the case of definition (1) of the above powder size, the average powder size is referred to as an average major axis length, and in the case of definition (2), the average powder size is referred to as an average plate diameter, (maximum major axis / thickness (Or height) is called the average plate ratio. In the case of definition (3), the average powder size is referred to as an average diameter (also referred to as an average particle diameter or an average particle diameter).
The average powder size of the powder is an arithmetic average of the above powder sizes, and is obtained by carrying out the measurement as described above for 500 primary particles. Primary particles refer to an independent powder without aggregation.

  The carbon black composition of the present invention can be prepared by mixing the above-described hydroxyl group-containing diamine compound, carbon black, and solvent together with various additives that are optionally added simultaneously or sequentially.

  The carbon black composition of the present invention is suitable for use in various fields that require high dispersion of carbon black, such as coating-type magnetic recording media, printing inks, paints, cosmetics, and batteries. For example, a coating composition for forming a magnetic recording medium can be obtained by adding the carbon black composition of the present invention as it is or by adding various additives used for the magnetic recording medium. The coating composition can be used, for example, to form a nonmagnetic layer, a backcoat layer, or a magnetic layer.

  The present invention further relates to a carbon black-containing coating film formed by drying the carbon black composition of the present invention.

  Since the carbon black composition of the present invention described above can contain carbon black in a highly dispersed state in a solvent, the carbon black composition can be coated on a support and dried, for example. Thus, it is possible to obtain a coating film having excellent surface smoothness without surface roughness due to aggregation. One aspect of the carbon black-containing coating film of the present invention is a backcoat layer, a nonmagnetic layer, a magnetic layer, etc. of a magnetic recording medium, but is not limited thereto, and can be used in various forms such as an antistatic sheet. It is.

  Drying at the time of forming the carbon black-containing coating film of the present invention can be performed by a known method and conditions for forming the coating film. Moreover, heat processing may be performed after drying. For example, in an embodiment in which a coating film is formed using the carbon black composition of the present invention containing an isocyanate compound, the diamine compound represented by the isocyanate group contained in the isocyanate compound and the general formula (I) is subjected to heat treatment after drying. The coating film strength can be increased by advancing the crosslinking reaction with the hydroxyl group contained in. For the heat treatment, a known technique relating to a crosslinking reaction (urethane reaction) between an isocyanate group and a hydroxyl group can be applied.

  EXAMPLES Hereinafter, although this invention is further demonstrated based on an Example, this invention is not limited to the aspect shown in an Example.

As the hydroxyl group-containing diamine compound (diamine diol) represented by the general formula (I), the following diamine diols 1 to 5 were synthesized.
As a comparative compound, monoamine diol 6 shown below was synthesized.

  A method for synthesizing the above compound is shown below.

[Synthesis Example 1]
1.0 part by mass of N, N-dimethylethylenediamine and 3.4 parts by mass of phenylglycidyl ether were mixed and reacted at 120 ° C. for 5 hours. It was confirmed by NMR that the obtained compound was diamine diol 1.

[Synthesis Example 2]
1.0 part by mass of N, N-diethylethylenediamine and 2.6 parts by mass of phenyl glycidyl ether were mixed and reacted at 120 ° C. for 5 hours. It was confirmed by NMR that the obtained compound was diamine diol 2.

[Synthesis Example 3]
1.0 part by mass of N, N-dimethylethylenediamine and 3.0 parts by mass of butyl glycidyl ether were mixed and reacted at 120 ° C. for 5 hours. It was confirmed by NMR that the obtained compound was diamine diol 3.

[Synthesis Example 4]
1.0 part by mass of N, N-dimethylethylenediamine and 1.6 parts by mass of 1,2-epoxybutane were mixed and reacted at 50 ° C. for 5 hours. It was confirmed by NMR that the obtained compound was diamine diol 4.

[Synthesis Example 5]
1.0 part by mass of N, N-dibutylethylenediamine and 1.5 parts by mass of butyl glycidyl ether were mixed and reacted at 120 ° C. for 5 hours. It was confirmed by NMR that the obtained compound was diamine diol 5.

[Comparative Synthesis Example 1]
1.0 part by mass of benzylamine and 2.8 parts by mass of phenylglycidyl ether were mixed and reacted at 120 ° C. for 5 hours. It was confirmed by NMR that the obtained compound was monoamine diol 6.

In the identification by NMR, ¹ H-NMR measurement was performed using 400 MHz NMR (AVANCE II-400 manufactured by BRUKER). ¹ H-NMR data of diamine diols 1, 2, 4 and monoamine diol 6 and their assignments are shown below.

<Diamine diol _{1 (C 22 H 32 N 2} O 4)>
¹ H-NMR (400MHz, CDCl ₃ , 25 ° C): 6.90-7.27ppm (10H, T), 4.08ppm (2H, m), 3.94ppm (4H, m), 2.44-2.86ppm (8H, Br), 2.23ppm (6H, S)

<Diamine diol _{2 (C 24 H 36 N 2} O 4)>
¹ H-NMR (400MHz, CDCl ₃ , 25 ° C): 7.27ppm (4H, T), 6.94ppm (2H, T), 6.90ppm (4H, D), 4.08ppm (2H, m), 3.94ppm (4H , m), 2.44-2.86ppm (12H, Br), 1.02ppm (6H, T)

<Diamine diol _{4 (C 12 H 28 N 2} O 2)>
¹ H-NMR (400MHz, CDCl ₃ , 25 ℃): 3.52ppm (2H, m), 2.25-2.68ppm (m, 12), 2.23ppm (6H, S), 0.97ppm (6H, T)

<Monoamine diol _{6 (C 25 H 29 NO 4} )>
¹ H-NMR (400MHz, CDCl ₃ , 25 ℃): 6.85-7.31ppm (15H, m), 4.10ppm (2H, m), 3.90ppm (4H, m), 2.73-2.92ppm (6H, Br)

[Example 1]
0.53 parts by mass of the following carbon black, 0.14 parts by mass of a polyether polyurethane resin, 0.22 parts by mass of a vinyl chloride resin (MR-104 manufactured by Kaneka) and 0.035 parts by mass of diamine diol 1 were added to 2-butanone (methyl ethyl ketone). ) It was suspended in a solution consisting of 5.4 parts by mass and 3.6 parts by mass of cyclohexanone. To the suspension, 50 parts by mass of 0.1 mmφ zirconia beads (manufactured by Nikkato) was added and dispersed for 15 hours to obtain a dispersion.
It was 52 nm when the dispersed particle diameter (particle diameter in a liquid by a dynamic light scattering method) was measured by the method mentioned later.
The dispersion was applied onto a PEN base manufactured by Teijin Ltd. using a doctor blade having a gap of 19 μm, and allowed to stand at room temperature for 30 minutes to dry to create a coating film. It was 2.6 nm when the average roughness of the produced coating film was measured by the method of the below-mentioned.

Carbon black (Mitsubishi Chemical # 950)
Average primary particle size: 18 nm
Nitrogen adsorption specific surface area: 260 m ² / g
DBP oil absorption: 79ml / 100g (powder)
pH: 7.5

Method for Measuring Dispersion Particle Diameter (Particle Diameter in Liquid by Dynamic Light Scattering Method) The dispersion liquid was diluted to a solid content concentration of 0.2% by mass using the same organic solvent used for dispersion (solid content and Represents the total mass of carbon black / amine additive / binder resin).
About the obtained dilution liquid, the average particle diameter measured using the dynamic light scattering type particle size distribution measuring apparatus LB-500 made from HORRIBA was made into the dispersed particle diameter. A smaller dispersed particle size means that carbon black does not aggregate and the dispersibility is better.

Coating Surface Roughness Measurement Method The surface roughness of the coating film was measured by setting Scan Length to 5 μm by scanning white light interferometry using a general-purpose three-dimensional surface structure analyzer NewView 5022 manufactured by ZYGO. Objective lens: 20 times, intermediate lens: 1.0 times, measurement field of view is 260 μm × 350 μm. The measured surface was filtered with HPF: 1.65 μm and LPF: 50 μm, and the centerline average surface roughness Ra value was determined.

[Example 2]
A dispersion and a coating film were prepared and evaluated in the same manner as in Example 1 except that 0.035 parts by mass of diamine diol 1 was changed to 0.037 parts by mass of diamine diol 2. The dispersed particle size was 44 nm, and the surface roughness was 2.4 nm.

[Example 3]
A dispersion and a coating film were prepared and evaluated in the same manner as in Example 1 except that 0.035 parts by mass of diamine diol 1 was changed to 0.031 parts by mass of diamine diol 3. The dispersed particle size was 43 nm, and the surface roughness was 2.0 nm.

[Example 4]
A dispersion and a coating film were prepared and evaluated in the same manner as in Example 1 except that 0.035 parts by mass of diamine diol 1 was changed to 0.021 parts by mass of diamine diol 4. The dispersed particle size was 56 nm, and the surface roughness was 4.4 nm.

[Example 5]
A dispersion and a coating film were prepared and evaluated in the same manner as in Example 1 except that 0.035 parts by mass of diamine diol 1 was changed to 0.039 parts by mass of diamine diol 5. The dispersed particle size was 45 nm and the surface roughness was 2.9 nm.

[Comparative Example 1]
A dispersion and a coating film were prepared and evaluated in the same manner as in Example 1 except that 0.035 parts by mass of diamine diol 1 was changed to 0.037 parts by mass of monoamine diol 6. The dispersed particle size was 200 nm, and the surface roughness was 9.5 nm.

  The above results are summarized in Table 1 below.

  Based on the above results, the hydroxyl group-containing diamine compound represented by the general formula (I) can highly disperse carbon black in a solvent, and further, thereby, a carbon black-containing coating film having high surface smoothness. It has been shown that formation is possible.

Evaluation of amine reactivity The reactivity of the diamine diol used in Examples 1 to 5 with respect to cyclohexanone and methyl ethyl ketone was evaluated by the following method.
The diamine diol and the solvent (cyclohexanone or methyl ethyl ketone) were weighed so as to correspond to equimolar amounts, mixed, and left in an oven at 50 ° C. for 1 hour. Then removed from the oven, dissolved in a deuterated solvent of CDCl _3, it was subjected to NMR measurement. In the NMR spectrum, when a peak different from the peak derived from the amine and the peak derived from the solvent was confirmed, the reactivity between the amine compound and the solvent was evaluated as judged to be reactive. It was confirmed that the diamine diol used in No. 5 showed no reactivity with cyclohexanone and methyl ethyl ketone.
On the other hand, when the same evaluation was performed for the diamine compounds shown below for comparison, it was confirmed that they showed reactivity with cyclohexanone and methyl ethyl ketone.

  From the above results, it can be confirmed that the hydroxyl group-containing diamine compound represented by the general formula (I) is poor in reactivity with the ketone group contained in cyclohexanone and methyl ethyl ketone. By using such a hydroxyl group-containing diamine compound, it is possible to provide a carbon black composition that does not cause a decrease in storage stability due to a side reaction with a ketone group or has a small decrease.

Evaluation of Volatility The diamine diol 1 used in Example 1, the diamine diol 2 used in Example 2, the monoamine diol 6 used in Comparative Example 1, and the diamine compound used for comparison in the evaluation of amine reactivity ( 1 g of each of the boiling points of 119 ° C. were weighed and vacuum-dried under the conditions of 100 ° C./3 hours, and the mass reduction rate of diamine diol 1, diamine diol 2, and monoamine diol 6 was less than 5%. On the other hand, the mass reduction rate of the diamine compound used for comparison in the evaluation of amine reactivity was 100%.
The high volatility of the compound used as the dispersant is not preferable for safety and causes a decrease in the storage stability of the carbon black dispersion. On the other hand, from the above results, it can be confirmed that the diamine diol used in the examples has low volatility. About this point, it is thought that the hydroxyl group contained in diamine diol has contributed to the volatility fall.

  From the above results, it was confirmed that the diamine diol used in the examples can highly disperse carbon black and can provide a carbon black composition having excellent storage stability. .

  The present invention is useful in various fields such as a magnetic recording field, a printing field, and a cosmetic field.

Claims (12)

A carbon black composition comprising carbon black and a hydroxyl group-containing diamine compound represented by the following general formula (I) in a solvent.
[In General Formula (I), R ¹ represents an alkyl group having 3 to 21 carbon atoms, an alkoxyalkyl group having 5 to 25 carbon atoms, an arylalkyl group, or an aryloxyalkyl group, and two R ^{1 s} are different from each other. Or at least one R ¹ includes a hydroxyl group as a substituent; R ² represents an alkyl group or a cycloalkyl group that may be bonded to a nitrogen atom via a linking group; The two R ^{2 s} may be different or the same, provided that neither of the two R ² contains a hydroxyl group; L represents an alkylene group. ] The carbon black composition according to claim 1, wherein the total number of hydroxyl groups contained in the two R ¹ in the general formula (I) is 2 or more. The carbon black composition according to claim 1, wherein two R ^{1 s} in the general formula (I) each contain one or more hydroxyl groups. The carbon black composition according to any one of claims 1 to 3, wherein the hydroxyl group-containing diamine compound represented by the general formula (I) is a hydroxyl group-containing diamine compound represented by the following formula (II).
[In General Formula (II), X represents a hydroxyl group-containing alkylene group, and the group represented by -XY is synonymous with the group represented by R ¹ in General Formula (I), and two X, Y may be different or the same, and R ² and L have the same meaning as in general formula (I). ] The carbon black composition according to any one of claims 1 to 4, wherein the hydroxyl group-containing diamine compound represented by the general formula (I) is a hydroxyl group-containing diamine compound represented by the following formula (III).
[In general formula (III), Z is a substituent which forms a group represented by R ¹ in general formula (I) together with linking —CH (OH) CH ₂ —, and the two Zs are different from each other. Or R ² and L are as defined in general formula (I). ] The carbon black composition according to any one of claims 1 to 5, wherein the hydroxyl group-containing diamine compound represented by the general formula (I) is a hydroxyl group-containing diamine compound represented by the following formula (IV).
[In general formula (IV), Z is a substituent which forms a group represented by R ¹ in general formula (I) together with linking —CH (OH) CH ₂ —, and the two Zs are different from each other. Or R ² has the same meaning as in formula (I). ] The carbon black composition according to claim 1, further comprising a binder resin. The carbon black composition according to claim 7, wherein the binder resin is selected from the group consisting of a vinyl copolymer and a polyurethane resin. The carbon black composition according to any one of claims 1 to 8, further comprising a polyisocyanate compound. The carbon black composition according to claim 1, wherein the solvent includes a ketone solvent. The carbon black containing coating film formed by drying the carbon black composition of any one of Claims 1-10. The carbon black containing coating film of Claim 11 formed by heat-processing after the said drying.