JPH0561264A - Electrophotographic developer - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic developer superior in image density or the like by using a specified resin acid ester liquid as the total carrier or a part of it. CONSTITUTION:The electrophotographic developer comprises toner particles dispersed in the liquid carrier and this liquid carrier contains, as the total or partial carrier, the liquid fatty acid ester. This fatty acid ester is selected from those represented by formulae I-III in which each of R1 and R2 is -OCOnH2n+1, n being 2-28, and one of them may be OH; and each of R3 and R4 is the same as R1 and R2. This fatty acid ester is used together with one of an aliphatic hydrocarbon A, a silicone oil B, a mineral oil C, and a vegetable oil D, and a suitable mixing ratio of each oil is as follows; A 20-90weight%, B 20-90weight%, C 20-70weight%, and 20-70weight%, thus permitting the obtained toner to be free from odor, capable of forming an image superior in uniformity of a solid part and gradation, and reduced in tendency to attach to a heating roller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic developer, and more particularly to improvement of a carrier liquid for a liquid developer.

[0002]

2. Description of the Related Art In the wet development method, which is one of the applications of electrostatic photography, a toner containing a colorant or a charge control agent as a main component is dispersed in a carrier liquid having high electrical insulation and a low dielectric constant. It is a method of developing an electrostatic latent image with a liquid developer. Since this wet development method is excellent in gradation reproducibility and resolution, a high quality image can be formed.
Further, it is more effective than the dry method in fixing an image because it does not require heating.

The conditions required for the carrier in the liquid developer used in such an advantageous wet development method are as follows.

1) The electrical resistance is high enough to retain the charge of the toner and the dielectric constant is low.

2) It is chemically inert and does not attack the toner, the electrostatic latent image holding surface and the materials of the apparatus, such as various metals, plastics, rubbers, etc. even at high or low temperatures.

3) It is volatile and easy to dry.

4) No toxicity.

5) No flammability or high flash point.

6) No odor.

As conventional carrier liquids, various hydrocarbons such as aliphatic hydrocarbons such as ligroin and cyclohexane, chlorinated aliphatic hydrocarbons such as benzene, toluene, xylene and tetrachlorohydrocarbon, and polysiroquine have been tried. In particular, a fixed fraction of petroleum (150-220 ° C)
A mixture of isoparaffin-based aliphatic hydrocarbons (isobars G, H, L, M and V manufactured by Exxon Co., Shell Zol T manufactured by Shell Co., etc. as commercial products) is generally used.
These mixed aliphatic hydrocarbons have a volume resistivity of 10 ¹⁴ Ωc.
It has m and a dielectric constant of about 2 and exhibits non-polarity due to its low dielectric constant and high electric resistance, and satisfies the conditions of 1), and can also meet the conditions of 2), 3) and 4). But,
There are problems in 5) flammability (flash point about 50 ° C) and 6) odor. That is, this type of carrier does not have a peculiar odor when it is volatilized in the step of drying the copy after development, and in particular, when a large number of copies are continuously obtained, a ventilation device or the like is provided to eliminate the odor. There is a need. The use of chloro derivatives of aliphatic hydrocarbons to avoid odors and flammability causes toxicity or safety problems.

Silicone oil is a carrier liquid having high safety and low odor. Since silicone oil is expensive and its SP value is too low as 4 to 5, it has disadvantages such as poor dispersibility of the toner and easy aggregation when used as a carrier liquid. Further, there is a problem that the drying property is poor and the copy is difficult to fix. Further, a carrier liquid containing a fluorine-based solvent has been proposed, but this is also expensive like a silicone oil and has a low SP value, so that there is a problem that the toner easily aggregates.

[0012]

SUMMARY OF THE INVENTION The present invention provides an electrophotographic developer that satisfies all the above-mentioned requirements for a carrier and eliminates the drawbacks of conventional carriers. That is, the present invention has excellent electrical insulation and dielectric properties, is inert enough not to attack various metals, plastics, rubbers and the like at high and low temperatures, has no particular odor and toxicity, and therefore is not harmful to the human body. It is an object of the present invention to provide a nonflammable electrophotographic developer that is completely safe and does not cause a fire. Further, the present invention provides a developer which has high solid uniformity and gradation and does not cause offset even when the toner is fused to the heat roller even in the heat roller fixing method.

[0013]

The present invention provides an electrophotographic developer comprising toner particles dispersed in a carrier liquid.
A developer for electrophotography, characterized in that a fatty acid ester liquid is used as all or part of the carrier liquid.

Since the fatty acid ester of the present invention has good solubility, it has been found that the solid uniformity and gradation are improved by mixing with the other solvent.

As the fatty acid ester, at least one of the above general formulas (1) to (7) is used. Further, it is advisable to use such a fatty acid ester in combination with any one of aliphatic hydrocarbon, silicone oil, mineral oil and vegetable oil. The proper mixing ratio of these is 20 to 90 wt% for aliphatic hydrocarbon and silicone oil, 20 to 70 wt% for mineral oil, and 20 to 80 wt% for vegetable oil. Outside this proper mixing ratio, gradation and solid uniformity are reduced by one or two steps.

As the aliphatic hydrocarbon, kerosene, isododecane, isoper G, H, L, M, V (manufactured by Exxon Chemical Co.) and the like, and as the silicone oil, dimethyl polysiloxane, methylphenyl polysiloxane, cyclic dimethyl polysiloxane, etc., minerals. Examples of the oil include mineral spirits and rosin oil, and examples of the vegetable oil include sesame oil, rapeseed oil, sunflower oil, soybean oil, castor oil, dehydrated castor oil, cottonseed oil, and cutting oil.

Examples of the fatty acid esters represented by the general formulas (1) to (3) are as follows.

[0018]

[Chemical 5]

[0019]

[Chemical 6]

Examples of the fatty acid ester represented by the general formula (4) are as follows.

[0021]

[Chemical 7]

Examples of the fatty acid ester represented by the general formula (5) are as follows.

No. 26 CH ₃ COCH ₂ COOCH ₃ No. 27 CH ₃ COCH ₂ COOC ₂ H ₅ No. 28 CH ₃ COCH ₂ -CH ₂ OCH ₃ No. 29 CH ₃ COOCH ₂ -CH ₂ -OC ₂ H ₅ No.30 CH ₃ COOC ₂ H ₄ OC ₂ H ₄ OCH ₃ No. 31 CH ₃ COOC ₂ H ₄ OC ₂ H ₄ OC ₂ H ₅ No. 32 CH ₃ COOC ₂ H ₄ OC ₂ H ₄ OC ₄ H ₉ No.33 C ₁₀ H ₂₁ COCH ₂ COOC ₁₀ H ₂₁ No.34 C ₁₂ H ₂₅ COCH ₂・ CH ₂ -COOC ₁₂ H ₂₅ No.35 C ₁₅ H ₃₁ COCH ₂・ CH ₂ -COOC ₁₅ H ₃₁ No.36 C ₂₀ H ₄₁ COCH ₂・ CH ₂ -COOC ₂₀ H ₄₁ No.37 C ₁₀ H ₄₁ CO (CH ₂ ) ₁₂・ COOC ₂₀ H ₄₁ No.38 CH ₃ CO (CH ₂ ) ₂₀・ COOCH ₃ General formula (6 Examples of the fatty acid ester are as follows.

[0024]

[Chemical 8]

Examples of the fatty acid ester of the general formula No. 7 are as follows.

[0026]

[Chemical 9]

[0027]

【Example】

Example 1 5 g of carbon black and 10 g of styrene-methacrylic acid copolymer were added to 0.5 liter of the dispersion liquid of the fatty acid ester of No. 1 and kneaded.
Dilution to g / l gave a liquid developer containing toner with a particle size distribution of 0.8μ.

Next, when this liquid developer was supplied to the electrostatic latent image on the zinc oxide photoconductor, a positive image of ID 1.29 was developed. Further, this was exposed to warm air at 50 ° C. for 20 seconds to carry out dry fixing. No odor associated with volatilization of the dispersion during drying was detected.

Example 2 10 g of methylmethacrylate resin particles having 1 g of phthalocyanine blue and 0.5 to 0.8 .mu.m particle size distribution in 0.5 liter of a dispersion of the fatty acid ester of No. 3
And then diluted to 5 g / l in the above dispersion,
Further, 2 g of a polarity control agent (10% solution in the above liquid was added to obtain a liquid developer having a toner having a polarity. Next, when this developer was supplied to the electrostatic latent image on the selenium photoreceptor, A positive image of ID 1.17 was obtained, which was dried and fixed in the same manner as in Example 1 to give exactly the same result, and no offset occurred in the heat roller fixing. Therefore, the one using Isopar H was fused to the heat roller, and an offset occurred on the copy.

Example 3 0.8 in 0.5 liter of a dispersion of isododecane
A toner in which 5 g of polyethylene fine particles having a particle size distribution of up to 5 μm are dispersed, diluted to 5 g / l in a dispersion liquid of a No. 5 fatty acid ester, and 2 g of metal soap is added at 10% to polarize the toner. A liquid developer containing was prepared.
Next, when this developer was supplied to the electrostatic latent image on the poly-N-vinylcarbazole-trinitrofluorenone type photoreceptor, it was developed into a positive image. When this was further exposed to warm air at 150 ° C. for 30 seconds and dried and fixed, the odor associated with volatilization of the dispersion liquid was not sensed at all, and a toner image of polyethylene fine particles was developed.

Example 4 Toner (toner for Ricoh DT750 manufactured by Ricoh) 50 g
A developer was prepared by using 2.0 liters of the compound No. 13 as the dispersion liquid. For comparison, Isopar H was used in the dispersion and was similarly copied. The No. 13 compound had a resolution of 6.3 mm / line and had no odor, and the Isopar H had a resolution of 5.6 mm / line and had a slight odor.

Example 5 Toner (Toner for Ricoh DT-1800R Recopy)
A developer was prepared by using 2.0 liters of the compound of No. 14 as a dispersion liquid in 100 g. For comparison, Isopar G was used in the dispersion and similarly copied. The compound of No. 14 had a resolution of 7.1 mm / line and had no odor, and the compound of Isopar G had a resolution of 5.6 mm / line and had a large odor.

Example 6 A copy was made in the same manner as in Example 4 except that the compound of No. 15 was used in place of No. 13, and the resolution was 6.3 mm / line and there was no odor.

Example 7 Compound No. 13 and silicone oil KF96.1.5
A copy was made in the same manner as in Example 4 except that the 9/1 mixture was used, and the resolution was 7.1 mm / line and there was no odor.

Example 8 A copy was made in the same manner as in Example 4 except that the 8/2 mixture of the compound No. 13 and Isopar H was used, and the resolution was 7.1 mm / line and there was no odor.

Example 9 A copy was made in the same manner as in Example 4 except that a 7/3 mixture of the compound of No. 13 and mineral oil was used, and the resolution was 8.
There was no odor at 0 mm / piece.

Example 10 A copy was made in the same manner as in Example 4 except that the 5/5 mixture of the compound of No. 13 and corn oil was used, and the resolution was 8.0 mm / line and there was no odor.

Example 11 A copy was made in the same manner as in Example 4 except that a 4/6 mixture of the compound of No. 15 and castor oil was used, and the resolution was 7.1 mm / line and there was no odor.

Example 12 Compound No. 16 (300 g), carbon black (Mitsubishi
44) 30 g and polylauryl methacrylate 50 g were placed in a ball mill and dispersed for 72 hours to prepare a concentrated toner.
When 30 g of this concentrated toner was dispersed in 2 liters of the compound of No. 16 and copied in the same manner as in Example 4, the resolution was 6.
It was 3 mm / piece and had no odor.

Example 13 In place of the compound of No. 16 in Example 12, No. 1
6 compound and silicone oil KF96.1.0 5 /
When copied in the same manner except that 5 mixture was used,
The resolution was 8.0 mm / line and there was no odor.

Example 14 In Example No. 12, N compound was used instead of No. 16 compound.
When a copy was made in the same manner except that an 8/2 mixture of the o.16 compound and Isopar H was used, the resolution was 7.1 mm /
There was no odor in the book.

Example 15 In Example No. 12, the compound of No. 16 was replaced with N.
When a copy was made in the same manner except that a 5/5 mixture of the o.16 compound and mineral oil was used, the resolution was 7.1 mm / line and there was no odor.

Example 16 In Example 12, instead of the compound of No. 16, No. 1 was used.
When a copy was made in the same manner except that a 6/4 mixture of the compound No. 6 and sesame oil was used, the resolution was 7.1 mm / line and there was no odor.

Example 17 In Example 12, instead of the compound of No. 16, No. 1
When a copy was made in the same manner except that an 8/2 mixture of the compound No. 6 and soybean oil was used, the resolution was 8.0 mm / line and there was no odor.

Example 18 Instead of the compound of No. 16 in Example 12, No. 1
A copy was made in the same manner except that a 6/4 mixture of the compound of No. 6 and cyclic dimethyl polysiloxane was used, and the resolution was 7.1 mm / line and there was no odor.

Example 19 In Example 12, instead of the compound of No. 16, No. 2 was used.
When copying was performed in the same manner except that the compound of No. 5 was used, the resolution was 6.3 mm / line and there was no odor.

Example 20 In Example 12, No. 2 was used instead of No. 16 compound.
When copying was performed in the same manner except that the compound of 4 was used, the resolution was 6.3 mm / line and there was no odor.

Example 21 In Example 12, instead of the compound of No. 16, No. 2 was used.
When copying was performed in the same manner except that the compound of No. 3 was used, the resolution was 6.3 mm / line and there was no odor.

Example 22 In Example 12, instead of the compound of No. 16, No. 2 was used.
When copying was performed in the same manner except that the compound of No. 2 was used, the resolution was 6.3 mm / line and there was no odor.

Example 23 In Example 12, No. 2 was used instead of No. 16 compound.
When copying was performed in the same manner except that the compound of No. 1 was used, the resolution was 7.1 mm / line and there was no odor.

Example 24 Instead of the compound of No. 13 in Example 4, No. 26 was used.
When copied in the same manner except that the compound of
There was no odor at an image density of 1.29. On the other hand, for comparison, the product using Isopar H had an odor at a resolution of 1.16.

Example 25 In Example 5, instead of the compound of No. 14, No. 27 was used.
When copied in the same manner except that the compound of
There was no odor at an image density of 1.26. On the other hand, for comparison, the product using Isopar G had a resolution of 1.15 and had a slight odor.

Example 26 In Example 24, the compound of No. 26 was replaced by No. 2
When copying was performed in the same manner except that the compound of No. 8 was used, the image density was 1.35 and there was no odor.

Example 27 In Example 24, instead of the compound No. 26, No. 2
6 was used in the same manner except that a 9/1 mixture of KF96.1.5 was used, and an image density of 1.33 was obtained.
There was no odor.

Example 28 In Example 24, the compound of No. 26 was replaced with No. 2
When a copy was made in the same manner except that an 8/2 mixture of the compound No. 6 and Isopar H was used, there was no odor at an image density of 1.32.

Example 29 In Example 24, the compound of No. 26 was replaced with No. 2
When a copy was made in the same manner except that a 7/3 mixture of the compound No. 6 and mineral oil was used, the image density was 1.30 and there was no odor.

Example 30 Instead of the compound of No. 26 in Example 24, No. 2 was used.
When a copy was made in the same manner except that a 5/5 mixture of the compound of 6 and corn oil was used, the image density was 1.35 and there was no odor.

Example 31 In Example 24, instead of the compound of No. 26, No. 2 was used.
When a copy was made in the same manner except that a 4/6 mixture of the compound of Example 8 and castor oil was used, the image density was 1.38 and there was no odor.

Example 32 In Example 12, instead of the compound of No. 16, No. 2 was used.
When copying was performed in the same manner except that the compound of 9 was used, the image density was 1.31 and there was no odor.

Example 33 In Example 24, instead of the compound of No. 26, No. 2 was used.
When copying was performed in the same manner except that the compound of 9 was used, the image density was 1.26 and there was no odor.

Example 34 In Example 24, the compound of No. 26 was replaced with No. 3
When copying was performed in the same manner except that the compound of 0 was used, the image density was 1.28 and there was no odor.

Example 35 In Example 24, instead of the compound of No. 26, No. 3 was used.
When copying was performed in the same manner except that the compound of No. 1 was used, the image density was 1.28 and there was no odor.

Example 36 5 g of carbon black and 10 g of lauryl methacrylate-methacrylic acid copolymer were added to 0.5 liter of a dispersion liquid of the compound of No. 34 and kneaded to make 3 g / l of the dispersion liquid. Diluted to obtain a liquid developer containing a toner having a particle size distribution of 0.3 to 0.6μ. Next, when this liquid developer was supplied to the electrostatic latent image on the zinc oxide photoconductor, a positive image having an image density of 1.31 was developed. Further, this was exposed to warm air at 50 ° C. for 20 seconds to carry out dry fixing. No odor associated with volatilization of the dispersion during drying was detected.

Example 37 1 in 0.5 liter of a dispersion of the compound of No. 37
g of phthalocyanine blue and 10 g of methylmethacrylate resin particles having a particle size distribution of 0.3 to 0.8 .mu.m are dispersed, and then the dispersion liquid is diluted to 3 g / l. 10% solution) was added to obtain a liquid developer having a toner having a polarity. Next, when this developer was supplied to the electrostatic latent image on the selenium photoreceptor, a positive image having an image density of 1.16 was obtained. This was dried and fixed in the same manner as in Example 36, but similar results were obtained. Also, no offset occurred in the heat roller fixing. For comparison, in the case of using Isoper H, the toner was fused to the heat roller, and the offset occurred on the copy.

Example 38 0.8 in 0.5 liter of a dispersion of Isopar H
Disperse 3 g of polyethylene fine particles having a particle size distribution of up to 5 μm, dilute this to 3 g / l in the liquid of the compound of No. 39, and further add 2 g of metal soap to the above solution by adding a 10% solution in the liquid to impart polarity. A liquid developer containing the prepared toner was prepared. Next, when this developer was supplied to poly-N-vinylcarbazole as an electrostatic latent image on a trinitrofluorenone type photoreceptor, a positive image was developed. When this was further exposed to warm air at 130 ° C. for 30 seconds and dried and fixed, the odor associated with volatilization of the dispersion was not sensed at all, and the toner image of polyethylene fine particles was fused.

Example 39 A developer was prepared by using 2.0 g of the compound of No. 41 as a dispersion in 50 g of toner (Recopy DT850 toner manufactured by Ricoh, modified to heat roller fixing). For comparison, a product using Isopar H in the dispersion was prepared and
Copied with T-850.

When the compound No. 41 was used, the solid uniformity was good, the gradation was 8 steps, there was no odor, and it did not adhere to the heating roller. In the case of Isopar H, the solid uniformity was rather poor, the gradation was 7, and there was a slight odor, and it adhered to the heat roller.

Example 40 Toner (Recopy DT-5700R Toner manufactured by Ricoh) 1
A developer was prepared by using 2.0 liters of the compound No. 42 as a dispersion in 00 g. For comparison, a developer was prepared using Isopar G in the dispersion liquid, and DT-5700R
I made a copy.

In the case of the compound No. 42, the solid uniformity was good, the gradation was 8 steps, there was no odor, and it did not adhere to the heating roller. In the case of Isopar G, the solid uniformity is poor,
The gradation was 6 steps and the odor was large, and it adhered to the heat roller.

Example 41 A copy was prepared in the same manner as in Example 39 except that the compound of No. 41 was replaced with the compound of No. 43. The solid uniformity was good, the gradation was 8 steps, there was no odor, and it did not adhere to the heat roller.

Example 42 A copy was made in the same manner except that the No. 41 compound of Example 39 was replaced with an 8/2 mixture of the No. 41 compound and silicone KF96.1.5. The solid uniformity was very good, the gradation was 9 steps, there was no odor, and it did not adhere to the heat roller.

Example 43 A copy was made in the same manner except that the No. 41 compound of Example 39 was replaced with a 7/3 mixture of No. 41 compound and Isopar H. The results were similar to those of Example 42 and were excellent.

Example 44 A copy was prepared in the same manner except that the No. 41 compound of Example 39 was replaced with a 7/3 mixture of the No. 41 compound and mineral oil. The results were similar to those of Example 42 and were excellent.

Example 45 A copy was prepared in the same manner except that the No. 41 compound of Example 39 was replaced with an 8/2 mixture of No. 41 compound and corn oil. The results were similar to those of Example 42 and were excellent.

Example 46 A copy was made in the same manner except that the compound of No. 41 of Example 39 was replaced with the compound of No. 43 and castor oil in a 7/3 mixture. The results were similar to those of Example 42 and were excellent.

Example 47 Instead of the compound of No. 16 in Example 12, No. 44
Copying was carried out in the same manner as in Example 40 except that the compound was used. As a result, the solid uniformity was good, the gradation was 7 steps, there was no odor, and adhesion of the toner to the heat roller was not recognized.

Example 48 A solid copy was obtained in the same manner as in Example 47 except that the No. 44 compound of Example 47 was replaced with a 5/5 mixture of the No. 44 compound and silicone oil KF96.1.0. The gradation was good, the gradation was 7 steps, there was no odor, and there was no adhesion to the heat roller.

Example 49 A solid copy was obtained in the same manner as in Example 47 except that the No. 44 compound of Example 47 was replaced with an 8/2 mixture of Isopar H and the solid uniformity was good. Sex 8
There was no step, no odor, and no adhesion to the heat roller.

Example 50 A copy was made in the same manner except that the No. 44 compound of Example 47 was replaced with a 5/5 mixture of mineral oil and the solid uniformity was good. Gradation is 8 steps,
There was no odor and no adhesion to the heat roller.

Example 51 A copy was made in the same manner except that the No. 44 compound of Example 47 was replaced with a 6/4 mixture of the No. 44 compound and sesame oil. 8 tones
There was no odor and no adhesion to the heat roller.

Example 52 A copy was made in the same manner except that the No. 44 compound of Example 47 was replaced with the 8/2 mixture of the No. 44 compound and soybean oil. Gradation is 8 steps,
There was no odor and no adhesion to the heat roller.

Example 53 A copy was made in the same manner except that the No. 44 compound of Example 47 was replaced with a 6/4 mixture of the No. 44 compound and cyclic dimethyl polysiloxane. The gradation was good, the gradation was 8 steps, there was no odor, and there was no adhesion to the heat roller.

Example 54 Instead of the compound of No. 41 in Example 39, No. 45
When copied in the same manner except that the compound of
The solid uniformity was good, the gradation was 8 steps, and there was no odor.

Example 55 Instead of the compound of No. 41 in Example 39, No. 46 was used.
When copied in the same manner except that the compound of
The same excellent results as in Example 54 were obtained.

Example 56 Instead of the compound of No. 41 in Example 39, No. 47 was used.
When copied in the same manner except that the compound of
The same excellent results as in Example 54 were obtained.

Example 57 Instead of the compound of No. 41 in Example 39, No. 48
When copying was carried out in the same manner except that the compound of Example 1 was used, excellent results similar to Example 54 were obtained.

Example 58 Instead of the compound of No. 41 in Example 39, No. 49
When copied in the same manner except that the compound of
The same excellent results as in Example 54 were obtained.

[0088]

The electrophotographic developer of the present invention is odorless,
It is possible to form an image having excellent solid uniformity and gradation, and further, it is possible to prevent the toner from being fused to the heating roller.

Claims (3)

[Claims] 1. An electrophotographic developer obtained by dispersing toner particles in a carrier liquid, wherein a fatty acid ester liquid is used as all or part of the carrier liquid. 2. The electrophotographic developer according to claim 1, wherein the fatty acid ester is at least one of the following general formulas (1) to (7). [Chemical 1] [Chemical 2] R ₅ COOR ₆ (4) (where R ₅ , R ₆ : C _n H _{2n + 1} , OC _n H _{2n + 1} [n =
1-20] Benzyl or cyclohexyl) R ₅ CO (CH ₂ ) _m COOR ₆ (5) (where R ₅ and R ₆ are the same as described above, m = 1 to 20) ] _{(Wherein, R 7, R 12: C} n H 2n + 1 [n = 1 to 20] _{R 8, R 11: C n} H 2n + 1 [n = 1 to 10] _{R 9, R 10: C n} H _{2n + 1} [n = 1 to 8] m, p = 1 to 10) 3. The electrophotographic developer according to claim 2, wherein any one of an aliphatic hydrocarbon, a silicone oil, a mineral oil and a vegetable oil is used in combination with a fatty acid ester.