JP6224975B2 - Conductive material - Google Patents

Description

  The present invention relates to a conductive material suitably used as a constituent material of a conductive member such as a developing roll, a charging roll, and a transfer roll in an electrophotographic apparatus such as a copying machine, a printer, and a facsimile machine.

  Conventionally, as a constituent material of conductive members such as a developing roll, a charging roll, a transfer roll, a toner supply roll, and a transfer belt, a conductive material obtained by adding an ionic conductive agent to a polar polymer such as urethane has been used. In this type of conductive material, the electric resistance is adjusted to a predetermined range (medium resistance region) by adjusting the amount of the ionic conductive agent added to the polar polymer.

  However, depending on the type of ionic conductive agent, there is a limit in the range in which the electric resistance can be lowered, and when the limit is reached, there is a problem that the electric resistance cannot be reduced no matter how much the ionic conductive agent is added. .

  Therefore, Patent Document 1 proposes a conductive material that can adjust the electrical resistance to a lower range than before by using a specific ionic conductive agent.

Japanese Patent No. 3744339

  However, when the quaternary ammonium salt described in Patent Document 1 is used as the ionic conductive agent, the resistance value of the conductive material increases when voltage is continuously applied to the conductive material, and the current-carrying durability is poor. all right. One of the causes of poor energization durability is that the quaternary ammonium salt bleeds during energization and the amount of ionic conductive agent decreases. This seems to be because the electric transfer of the ionic conductive agent has become too easy because the electric resistance can be adjusted to a lower range than before.

  The problem to be solved by the present invention is to provide a conductive material capable of satisfying both low electrical resistance and durability for energization.

In order to solve the above problems, a conductive material according to the present invention is a surface-treated calcium carbonate in which calcium carbonate is surface-treated with a quaternary ammonium salt represented by the following general formula (1) as an ionic conductive agent and a fatty acid. And the gist of which is contained.
(Chemical formula 1)
m [(C _n H _{2n + 1} ) (CH ₃ ) ₃ N] ⁺ · X ^m− (1)
_However, C _{n H 2n + 1} represents an alkyl group of straight chain, n is an integer from 5 to 11. X ^m− represents an m-valent anion, and m is an integer of 1 to 2.

  At this time, it is preferable that the carbon number of the fatty acid of the said surface treatment calcium carbonate is 6-31.

The anion of the quaternary ammonium salt is preferably one or more selected from ClO ₄ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ and Cl ⁻ .

  And it is preferable that the said quaternary ammonium salt and the said surface treatment calcium carbonate are added to the polar polymer. In this case, examples of the polar polymer include one or more selected from hydrin rubber, nitrile rubber, chloroprene rubber, and polyurethane.

  According to the conductive material according to the present invention, low electrical resistance and electric durability are obtained by including surface-treated calcium carbonate in which calcium carbonate is surface-treated with a fatty acid together with a specific quaternary ammonium salt as an ionic conductive agent. Both sexes can be achieved.

  At this time, when the carbon number of the fatty acid of the surface-treated calcium carbonate is 6 to 31, aggregation of the surface-treated calcium carbonate is suppressed, so that the effect of adding the surface-treated calcium carbonate can be further improved.

When the anion of the quaternary ammonium salt is one or more selected from ClO ₄ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ and Cl ⁻ , the low electrical resistance is particularly excellent.

  And low electrical resistance can be satisfied by adding a quaternary ammonium salt and surface treatment calcium carbonate to a polar polymer. In this case, when the polar polymer is one or more selected from hydrin rubber, nitrile rubber, chloroprene rubber, and polyurethane, the electric resistance of the polar polymer itself is low, so that the low electric resistance is particularly excellent.

  Next, an embodiment of the present invention will be described in detail.

The conductive material according to the present invention contains a quaternary ammonium salt represented by the following general formula (1) as an ionic conductive agent and surface-treated calcium carbonate obtained by surface-treating calcium carbonate with a fatty acid.
(Chemical formula 2)
m [(C _n H _{2n + 1} ) (CH ₃ ) ₃ N] ⁺ · X ^m− (1)
_However, C _{n H 2n + 1} represents an alkyl group of straight chain, n is an integer from 5 to 11. X ^m− represents an m-valent anion, and m is an integer of 1 to 2.

With such a conductive material, both low electrical resistance and energization durability can be achieved. This is presumably because the carboxylate anion of the fatty acid electrostatically interacts with the cation portion of the quaternary ammonium salt, thereby stabilizing the quaternary ammonium salt in an ionic state. If the long-chain alkyl group (C _n H _{2n + 1} ) in the cation part of the quaternary ammonium salt has less than 5 carbon atoms, the interaction with the carboxylate anion of the fatty acid is too strong and the cation part of the quaternary ammonium salt The movement is suppressed, and the low electrical resistance due to the quaternary ammonium salt cannot be obtained. On the other hand, if the long chain alkyl group (C _n H _{2n + 1} ) in the cation portion of the quaternary ammonium salt has more than 11 carbon atoms, the ionicity becomes lower due to the increase in the nonpolar part, and therefore the fatty acid carboxylate anion The interaction becomes weak, bleed of the quaternary ammonium salt cannot be suppressed, and current-carrying durability cannot be obtained. The long chain alkyl group (C _n H _{2n + 1} ) of the cation part of the quaternary ammonium salt has 5 to 11 carbon atoms, so that the charge amount of the cation part is well balanced with the charge amount of the carboxylate anion of the fatty acid. Both can interact with moderate van der Waals forces. As a result, it is presumed that the low electrical resistance and the current-carrying durability are compatible.

In the quaternary ammonium salt, the carbon number of the long-chain alkyl group (C _n H _{2n + 1} ) is such that the charge amount of the cation moiety is suppressed to moderately weaken the interaction with the carboxylate anion of the fatty acid, thereby lowering the electrical resistance. From the viewpoint of ease, etc., it is preferably 6 or more, more preferably 7 or more. On the other hand, from the viewpoint of enhancing the ionicity by suppressing the increase of the non-polar part and appropriately strengthening the interaction with the carboxylate anion of the fatty acid, and further enhancing the effect of suppressing the bleed of the quaternary ammonium salt, 10 or less, more preferably 9 or less.

In the quaternary ammonium salt, examples of the anion include halogen ions such as F ⁻ , Cl ⁻ , Br ⁻ and I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , SO ₄ ²⁻ , HSO ₄ ⁻ and CH ₃ SO ₄ ^{−. _{, C 2 H 5 SO 4 -}} , CH 3 SO 3 -, C 2 H 5 SO 3 -, COOH -, CF 3 SO 3 -, (CF 3 SO 2) 2 N - , and the like ^- (TFSI). These may be used alone or in combination of two or more. Among these, it is preferable to use ClO ₄ ⁻ , TFSI ⁻ , Cl ⁻ alone or in combination of two or more thereof from the viewpoint of particularly excellent low electrical resistance.

  The fatty acid of the surface-treated calcium carbonate is preferably composed of a fatty acid having a linear alkyl group from the viewpoint of interaction with a quaternary ammonium salt. The number of carbon atoms of the fatty acid is preferably 6 to 31 from the viewpoint of suppressing the aggregation of calcium carbonate to enhance the dispersibility and more effectively exhibiting the effect of suppressing the bleeding of the quaternary ammonium salt. . When the fatty acid has 6 or more carbon atoms, the effect of making the surface of the calcium carbonate hydrophobic is sufficient, and aggregation of the calcium carbonate is easily suppressed. Further, when the fatty acid has 31 or less carbon atoms, the effect of making the surface of the calcium carbonate hydrophobic is not too high, and aggregation of the calcium carbonate is easily suppressed. From this viewpoint, the number of carbon atoms of the fatty acid is more preferably 15 to 22, and further preferably 17 to 19.

  The surface treatment amount of the surface-treated calcium carbonate with a fatty acid is preferably 0.01 to 30% by mass. When the surface treatment amount is 0.01% by mass or more, the effect of making the surface of calcium carbonate hydrophobic is sufficient, and aggregation of calcium carbonate is easily suppressed. Further, when the surface treatment amount is 30% by mass or less, the effect of making the surface of calcium carbonate hydrophobic is not too high, and aggregation of calcium carbonate is easily suppressed. From such a viewpoint, the surface treatment amount is more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more. Moreover, More preferably, it is 20 mass% or less, More preferably, it is 5 mass% or less.

  The particle diameter of calcium carbonate is preferably 20 to 500 nm from the viewpoint of rubber hardness and rubber reinforcement. More preferably, it is 50-300 nm, More preferably, it is 70-200 nm. In addition, a particle diameter is represented by the 50% average particle diameter of the particle | grains measured by Shimadzu type particle size distribution analyzer CP-4L.

  The conductive material according to the present invention preferably contains a polar polymer. Fatty acids are ionized in protons in polar media to produce carboxylate anions of conjugated bases. By containing a polar polymer as a substrate, the effect of suppressing bleed of quaternary ammonium salts by fatty acids of surface-treated calcium carbonate is achieved. It is because it becomes easy to be demonstrated. Moreover, it is because low electrical resistance can be satisfied by adding a quaternary ammonium salt and surface-treated calcium carbonate to a polar polymer.

  The polar polymer is a polymer having a polar group, and examples of the polar group include a chloro group, a nitrile group, a carboxyl group, and an epoxy group. Specific examples of polar polymers include hydrin rubber, nitrile rubber (NBR), urethane (U), acrylic rubber (a copolymer of acrylic ester and 2-chloroethyl vinyl ether, ACM), chloroprene rubber (CR), Examples include epoxidized natural rubber (ENR). These may be used alone or in combination of two or more. Among these, hydrin rubber, nitrile rubber, chloroprene rubber, polyurethane, and the like are more preferable from the viewpoint that the polar polymer itself has low electrical resistance and is particularly excellent in low electrical resistance.

  Examples of hydrin rubber include epichlorohydrin homopolymer (CO), epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary. A copolymer (GECO) etc. can be mentioned.

  Examples of the polyurethane include a polyether type polyurethane having an ether bond in the molecule. A polyether type polyurethane can be produced by a reaction between a polyether having hydroxyl groups at both ends and a diisocyanate. The polyether is not particularly limited, and examples thereof include polyethylene glycol and polypropylene glycol. Although it does not specifically limit as diisocyanate, Tolylene diisocyanate, diphenylmethane diisocyanate, etc. can be mentioned.

  It is preferable that the compounding quantity of the quaternary ammonium salt with respect to a polar polymer exists in the range of 0.01-10 mass parts with respect to 100 mass parts of polar polymers. It becomes easy to reduce an electrical resistance to a desired value as the compounding quantity of a quaternary ammonium salt is 0.01 mass part or more. Further, when the blending amount of the quaternary ammonium salt is 10 parts by mass or less, the compatibility with the polar polymer is excellent, and bleed of the quaternary ammonium salt is easily suppressed except during the current-carrying durability (when not energized). . In this respect, the lower limit of the amount of the quaternary ammonium salt is preferably 0.1 parts by mass, and more preferably 0.3 parts by mass. Moreover, as an upper limit of the compounding quantity of a quaternary ammonium salt, 5 mass parts is preferable and 2 mass parts is more preferable.

  It is preferable that the compounding quantity of the surface treatment calcium carbonate with respect to a polar polymer exists in the range of 1-100 mass parts with respect to 100 mass parts of polar polymers. When the blending amount of the surface-treated calcium carbonate is 1 part by mass or more, the effect of suppressing bleeding of the quaternary ammonium salt at the time of energization durability is high. Moreover, the movement of a quaternary ammonium salt is not suppressed as the compounding quantity of surface treatment calcium carbonate is 100 mass parts or less, and low resistance can be maintained. In this respect, the lower limit of the amount of the surface-treated calcium carbonate is preferably 10 parts by mass, and more preferably 30 parts by mass. Moreover, as an upper limit of the compounding quantity of surface treatment calcium carbonate, 70 mass parts is preferable and 50 mass parts is more preferable.

  In addition to a specific quaternary ammonium salt and a specific surface-treated calcium carbonate, the conductive material of the present invention requires a crosslinking agent, a crosslinking accelerator, a processing aid, an anti-aging agent, a softening agent, a reinforcing agent, etc. It can be added depending on. Further, an ionic conductive agent other than a specific quaternary ammonium salt or an electronic conductive agent such as carbon black can be added to the conductive material of the present invention as necessary. The other ion conductive agent may be an ammonium salt or another type of ion conductive agent such as a phosphonium salt.

    The conductive material of the present invention includes, for example, the quaternary ammonium salt as an ionic conductive agent, the surface-treated calcium carbonate and various additives added as necessary to a polar polymer, and kneader these. It can be obtained by kneading using a kneading machine such as a Banbury mixer.

  The conductive material of the present invention thus obtained is not particularly limited as its application, but in an electrophotographic apparatus such as a copying machine, a printer, and a facsimile, a developing roll, a charging roll, a transfer roll, a toner supply roll, It is suitably used as a constituent material of a conductive member such as a transfer belt. The conductive material of the present invention is suitably used as a conductive material for forming a layer serving as a dielectric layer such as a base layer of a conductive member or a resistance adjusting layer.

  Hereinafter, the present invention will be described in detail using examples.

Example 1
Surface of quaternary ammonium salt represented by the following formula (2) as an ionic conductive agent with 2 parts by mass of a fatty acid having 18 carbon atoms with respect to 100 parts by mass of hydrin rubber (ECO, manufactured by Zeon, “Hydrin-T3106”) 30 parts by weight of treated surface treated calcium carbonate (“Vigot-15” manufactured by Shiraishi Kogyo Co., Ltd., average particle size 150 nm, treated amount of fatty acid 1 to 5% by mass), “DHT-4A” manufactured by Kyowa Chemical Co., Ltd. as an acid acceptor 10 parts by mass and 2 parts by mass of sulfur (“Sulfur-PTC”, manufactured by Tsurumi Chemical Co., Ltd.) as a crosslinking agent were added, and these were stirred and mixed with a stirrer to prepare a conductive material of Example 1. This was press-molded to produce a conductive sheet having a thickness of 0.7 mm.
(Chemical formula 3)
[(C ₈ H ₁₇ ) (CH ₃ ) ₃ N] ⁺ · ClO ₄ ⁻ (2)

(Examples 2-3)
The conductive materials of Examples 2-3 were prepared in the same manner as in Example 1 except that the carbon number of the long-chain alkyl group of the cation species of the ionic conductive agent was changed to 5 or 11, and the conductive materials of Examples 2-3 were prepared. A conductive sheet was prepared.

(Examples 4 to 5)
The conductive material of Examples 4-5 was prepared like Example 1 except having changed the carbon number of the fatty acid used for the surface treatment of the surface treatment calcium carbonate to 6 or 31. A conductive sheet was prepared. In addition, the surface treatment calcium carbonate of Examples 4 to 5 is a non-surface treated calcium carbonate “Brilliant-1500” manufactured by Shiraishi Kogyo Co., Ltd., having an average particle size of 150 nm) with hexanoic acid or hentria contanoic acid. Was prepared by surface-treating so as to be 1 to 5% by mass. The treatment amount was quantified by extracting the prepared surface-treated calcium carbonate using diethyl ether.

(Examples 6 to 9)
Conductive materials of Examples 6 to 9 were prepared in the same manner as in Example 1 except that the anionic species of the ionic conductive agent was changed from ClO ₄ ⁻ to TFSI ⁻ , Cl ⁻ , BF ₄ ⁻ , or PF ₆ ^−. The electroconductive sheet of Examples 6-9 was produced.

(Examples 10 to 12)
Example 10 is the same as Example 1 except that the polar polymer is changed from ECO to NBR (“Nipol DN302” manufactured by Nippon Zeon Co., Ltd.) or CR (“Skyprene B-30” manufactured by Tosoh Corporation) or the following polyurethane. -12 conductive materials were prepared and the conductive sheet of Examples 10-12 was produced.

(Preparation of conductive material containing polyurethane)
After 80 parts by mass of polytetramethylene ether glycol ("PTMG2000" manufactured by Mitsubishi Chemical Corporation) and 20 parts by mass of polypropylene glycol ("Excenol 2020" manufactured by Asahi Glass Co., Ltd.) were degassed and dehydrated at 80 ° C for 1 hour, MDI (Mitsui Chemicals) 32 parts by mass of “Cosmonate PH” manufactured by the company was mixed and reacted at 80 ° C. under a nitrogen atmosphere for 3 hours to prepare a urethane prepolymer. Subsequently, this urethane prepolymer was vacuum degassed at 90 ° C. for 30 minutes, and then 100 parts by mass of the urethane prepolymer, 50 parts by mass of glycerin diacetomonolaurate as a plasticizer, and a chain extender 1,4-butane A conductive material containing polyurethane was prepared by blending 3.5 parts by mass of diol, the same surface-treated calcium carbonate as in Example 1 and an ionic conductive agent, and expanding and mixing for 2 minutes under reduced pressure.

(Comparative Example 1)
Conductivity according to Comparative Example 1 was performed in the same manner as in Example 1 except that “Brilliant-1500” manufactured by Shiraishi Kogyo Co., Ltd., which is calcium carbonate not subjected to surface treatment, was used instead of surface-treated calcium carbonate. A conductive material was prepared, and a conductive sheet of Comparative Example 1 was produced.

(Comparative Examples 2-3)
A conductive material of Comparative Examples 2 to 3 was prepared in the same manner as in Example 1 except that the carbon number of the linear alkyl group of the cation species of the ionic conductive agent was changed to 4 or 12. A conductive sheet was prepared.

  Product characteristics evaluation was performed using each produced electroconductive sheet. The measurement method and evaluation method are shown below. These results are shown in Table 1.

(Electrical resistance)
Each conductive sheet was cut into 30 mm × 30 mm, and then a silver paste was applied thereon to produce a 10 mm × 10 mm electrode. Next, in a low temperature and low humidity environment of 15 ° C. × 10% RH, a voltage of 100 V was applied and the volume resistivity (Ω · cm) after 30 seconds was measured using model 237 (manufactured by KEITHLEY).

(Energization durability)
An energization endurance test was performed by continuously applying a constant current of DC 200 μA. The volume resistivity after energization endurance was measured according to the measurement method of electric resistance, and the difference between the initial volume resistivity and the volume resistivity LOG after energization endurance was calculated as a change width (energization endurance change width). The continuous application time (days) when this change width increased by one digit was obtained.

  From Comparative Example 1, it can be seen that if the calcium carbonate is not subjected to a surface treatment with a fatty acid, the volume resistivity change width increases by an order of magnitude on the third day of the current-carrying durability, and the current-carrying durability is poor. In addition, it can be seen from Comparative Example 2 that the electrical resistance increases when the long-chain alkyl group of the quaternary ammonium salt has 4 carbon atoms. Moreover, it can be seen from Comparative Example 3 that when the number of carbon atoms of the long-chain alkyl group of the quaternary ammonium salt is 12, the volume resistivity change width increases by an order of magnitude on the 10th day, and the energization durability is poor.

  On the other hand, from Examples 1 to 3, when calcium carbonate is subjected to a surface treatment with a fatty acid and the carbon number of the long-chain alkyl group of the quaternary ammonium salt is 5 to 11, the electric current is low and the electric current is low. It turns out that it is excellent also in durability.

  Further, it can be seen that when the carbon number of the fatty acid whose surface is treated with calcium carbonate is at least 6 to 31, the electrical resistance is excellent with low electrical resistance. Further, Examples 6 to 9 show that similar results can be obtained even in the case of other anionic species. Moreover, it turns out that the same result is obtained also from other polar polymers from Examples 10-12.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said Example at all, A various change is possible in the range which does not deviate from the summary of this invention.

Claims (6)

A conductive material comprising: a quaternary ammonium salt represented by the following general formula (1) as an ionic conductive agent; and a surface-treated calcium carbonate obtained by surface-treating calcium carbonate with a fatty acid.
(Chemical formula 1)
m [(C _n H _{2n + 1} ) (CH ₃ ) ₃ N] ⁺ · X ^m− (1)
_However, C _{n H 2n + 1} represents an alkyl group of straight chain, n is an integer from 5 to 11. X ^m− represents an m-valent anion, and m is an integer of 1 to 2. In the said General formula (1), n is an integer of 7-11, The electroconductive material of Claim 1 characterized by the above-mentioned. Conductive material according to claim 1 or 2, wherein the number of carbon atoms in the fatty acid of the surface treated calcium carbonate is 6-31. 4. The anion of the quaternary ammonium salt is one or more selected from ClO ₄ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ and Cl ^−. 5. The conductive material according to any one of the above. The conductive material according to any one of claims 1 to 4 , wherein the quaternary ammonium salt and the surface-treated calcium carbonate are added to a polar polymer. 6. The conductive material according to claim 5 , wherein the polar polymer is one or more selected from hydrin rubber, nitrile rubber, chloroprene rubber, and polyurethane.