JPH0120424B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin for electrophotographic toner. More specifically, the present invention relates to a highly durable resin for electrophotographic toners that exhibits good low-temperature fixability in a heat fixing method and does not cause offset or the like even after repeated copying. In recent years, plain paper copies using electrophotography and high-speed printers for computer terminals based on the same principle have become widely popular due to their ease of handling and excellent image quality. However, on the other hand, efforts are being made to increase the copying speed or to minimize the maintenance work of the equipment, and such improvements are also being made in terms of the toners used.
In particular, with regard to image fixing characteristics as copying speeds increase, it is important that the toner has properties that allow fixing at as low a temperature as possible, do not cause offset even at as high a temperature as possible, and are unaffected by various environments. The properties of toner resin are also an important factor in obtaining stable images. The present inventors conducted various studies regarding the improvement of electrophotographic toners from the standpoint of the resin used. As a result, they found that they have good fixing properties at low temperatures compatible with high-speed copying, and do not cause offset even at high temperatures. We have achieved a highly durable resin for electrophotographic toners that has excellent fixing properties and does not cause offset or the like even after repeated copying. That is, the present invention heats an unsaturated polyester resin having a number average molecular weight of 1,000 to 4,000 and has a double bond derived from an unsaturated dibasic acid in an amount of 0.05 to 2.0 equivalents per 1,000 g, or in the presence of a polymerization initiator, and converts it into substantially vinyl The resin for electrophotographic toner is further polymerized in the absence of a monomer and is solid at room temperature, and has a ratio of weight average molecular weight to number average molecular weight of 5 or more. The unsaturated dibasic acid in the present invention includes:
Examples include maleic acid, fumaric acid, tetrahydrophthalic acid, maleic anhydride, tetrahydrophthalic anhydride, itaconic acid, mesaconic acid, citraconic acid, and the like. In addition, the unsaturated polyester resin in the present invention is a polyester resin having a number average molecular weight of 1000 to 4000 obtained by polycondensation from a dibasic acid and a polyol, and which contains an unsaturated dibasic acid as a part of the dibasic acid. It is an unsaturated polyester resin containing. If the number average molecular weight of the unsaturated polyester resin is 1,000 or less, the softening point will drop significantly and caking will occur if left at room temperature, and offset will easily occur at high temperatures. On the other hand, if it exceeds 4000, gelation tends to occur during further polymerization reaction, and the fixing temperature also rises, making it impossible to obtain the desired toner. Representative examples of the dibasic acid component include orthophthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like. In addition, as a polyol component,
Ethylene glycol, 1,2-propylene glycol, 1,3 propylene glycol, 1,3 butylene glycol, 1,4 butylene glycol,
1,6 hexane glycol, neopentyl glycol, 3,3,5-trimethyl 2,4-pentanediol, dipropylene glycol, hydrogenated bisphenol A, bisphenol A, bisphenol A propylene oxide adduct, bisphenol A ethylene In addition to diols such as oxide adducts, trifunctional compounds such as trimellitic anhydride, glycerin, trimethylolethane, and trimethylolpropane can also be used. The polycondensation reaction of polyesterification is carried out by a conventional method in which the product water is produced at a temperature of 150 to 230°C in an inert gas stream without a solvent or in the presence of an organic solvent, with an acid excess in the range of 0 to 10%. It is done while distilling. The reaction can be monitored by measuring the acid value or hydroxyl value, calculating the molecular weight from this value, and stopping the reaction when a polyester having a molecular weight of 1,000 to 4,000 is obtained. The unsaturated polyester resin thus obtained is further subjected to a polymerization reaction by heating or in the presence of a polymerization initiator.
The temperature is raised to ~280°C and the reaction is carried out for about 1 to 10 hours, and in the presence of a polymerization initiator, the reaction is carried out at 150 to 240°C for about 1 to 20 hours, depending on the type of polymerization initiator. This is done by letting Typical examples of the polymerization initiators include cumene hydroperoxide, dicumyl peroxide, tertiary butyl hydroperoxide, 2,5-dimethylhexane 2,5-dihydroperoxide, 1,1 , 3,3 tetramethylbutyl hydroperoxide, tertiary butyl peroxide, tertiary butyl cumyl peroxide,
Examples include 2,5-dimethyl-2,5-di(tertiarybutylperoxy)hexyne-3. The amount of polymerization initiator is usually 0.05 to 2% by weight, preferably 0.05 to 2% by weight based on the unsaturated polyester resin.
It is used in a range of 0.05 to 1% by weight. Furthermore, the present invention is characterized in that the polyester resin is polymerized substantially in the absence of vinyl monomer. If a vinyl monomer such as styrene is copolymerized, offset will occur during continuous copying, which is undesirable. The polymer of unsaturated polyester resin obtained by the above method needs to have a ratio of number average molecular weight (Mn) to weight average molecular weight (Mw) (Mw/Mn) of 5 or more, preferably 5. ~40 range. However, if Mw/Mn is less than 5, offset tends to occur and the effect is small. In the present invention, the values of number average molecular weight and weight average molecular weight are measured under the following measurement conditions. GPC device: JASCO TWINCLE HPLC DETECTOR: SHODEX RI-SE-31 COLUMN: SHODEX GPCA-80M, 2 bottles Solvent: Tetrahydrofuran Flow rate: 1.2 ML/MIN Electrophotographic toner using the above resin for electrophotographic toner of the present invention When preparing a toner, other resins such as styrene resins, acrylic resins, epoxy resins, styrene-butadiene resins, and styrene-butadiene resins may be used to the extent that the effects of the present invention are not impaired.
It is okay to use a mixture of acrylic resins. The electrophotographic toner resin of the present invention usually contains various coloring pigments such as carbon black, charge control agents such as nigrosine and metal-containing dyes for adjusting triboelectric charging properties, and a charge control agent for improving offset properties. The polyolefin wax used, stearic acid derivatives, auxiliary agents such as silicone oil, and in the case of magnetic toner, magnetic iron oxide, reduced iron powder, etc. are mixed, kneaded in a molten state, and then the average particle size is 5. ~
It is finely pulverized to 20 μm and prepared as a dry toner, which is used as an electrophotographic toner. The dry toner prepared in this way can be fixed at low temperatures or high speeds (in the case of high-speed copying, the contact time with the heating roll is shortened, so the behavior is similar to the fixing conditions at low temperatures), and the There is no offset development to the roll, and there is little change in the amount of charge even in copying environments such as high humidity or in long-term continuous copying, and it has excellent performance that does not cause image quality defects such as fog. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 224 g of isophthalic acid, 89 g of phthalic anhydride,
Neopentyl glycol 208g, maleic anhydride
4.9g was gradually heated to 200-220℃ under a _N2 stream.
The mixture was allowed to react for 10 hours. The amount of water distilled out was 68 g, and the acid value at that time was 14. This polyester resin is
It contained 0.10 equivalent of unsaturated dibasic acid in 1000 g, and its number average molecular weight was 320,000. Furthermore this thing
After cooling down to 160℃, cumene hydroperoxide
Add 0.4g and leave to stir for 1 hour, then gradually raise to 200℃
The temperature was raised over 4 hours to further polymerize. Next, the product obtained in this way was transferred to a SUS vat, cooled and solidified, and then used as a toner resin.
(A) was produced. The glass transition temperature of the resin (A) thus obtained was measured by the DSC method and was found to be 66°C.
Also, the results of measuring the molecular weight distribution of this substance are Mw
=45000, Mn=6400, Mw/Mn=7.03,
MI value (ASTM-
D-1237-57T test method) was 15.0. 930 g of the above resin (A), 50 g of carbon black (manufactured by Mitsubishi Rayon Co., Ltd., trade name MA-600) and 20 g of nigrosine were mixed, melted and kneaded with a heated roll, and then pulverized using a fine grinder and classified. Particle size 5~
Particles of 15μ were collected to produce toner (A). Example 2 324 g of isophthalic acid, propylene glycol
152 g of fumaric acid and 5.8 g of fumaric acid were charged into a reactor equipped with a stirrer, heated and melted under a N ₂ stream, and an esterification reaction was carried out at 220° C. while distilling off the produced water. The reaction was stopped when the amount of distilled water reached 68 g and the acid value reached 16. This unsaturated polyester resin
It contained 0.2 equivalents of double bonds derived from unsaturated dibasic acids in 1000 g, and had a number average molecular weight of 3600.
After the temperature was further lowered to 150° C., 0.5 g of ditertiary butyl peroxide was added dropwise, and the mixture was left stirring for 30 minutes.
Then, the temperature was gradually raised to 220℃ over 4 hours.
It was further polymerized. What was obtained in this way
The liquid was transferred to a SUS vat and solidified by cooling to produce a toner resin (B) that is solid at room temperature. The glass transition temperature of the resin (B) thus obtained was measured and found to be 62°C. Also, the molecular weight distribution of this material was measured and the results were Mw=41000, Mn4800,
Mw/Mn=8.54, at 150℃ and 2160g
The MI value was 19.4. 930g of the above resin (B) and carbon black MA-600
and 20 g of nigrosine dye were mixed, melted and kneaded with a hot roll, pulverized using a pulverizer, and classified to collect particles with a particle size of 5 to 15 μm to produce toner (B). Example 3 232.4g of isophthalic acid, 89g of phthalic anhydride,
Neopentyl glycol 208g, maleic anhydride
4.9 g of the product was charged into a reactor equipped with a stirrer, heated and melted, and the resulting water was distilled off while the esterification reaction was carried out at 220°C. The reaction was stopped when the amount of distilled water reached 65 g and the acid value reached 28. This polyester resin is in 1000g
It contained 0.14 equivalents, and its number average molecular weight was 2,800. The temperature was further raised to 260°C and thermal polymerization was carried out for 3 hours.
The thus obtained product was cooled by liquid transfer in a SUS vat to produce a toner resin (C) that is solid at room temperature. The glass transition temperature of the resin (C) thus obtained was measured and was 67°C. Also, the molecular weight distribution of this material was measured and the results were Mw=35000, Mn=
6200, Mw/Mn=5.65, and the MI value was 26 at 150°C and 2160g. Toner was prepared using the above resin (C) in exactly the same manner as in Example 1.
(C) was produced. Examples 4 to 7 Toner resins were produced in the same manner as in Example 1 using the compositions and parts by weight shown in Table 1. Table 1 shows its characteristic values. Next, each toner was manufactured in the same manner as in Example 1.

[Table] Comparative Example 1 A toner resin (D) was produced in exactly the same manner as in Example 1, except that maleic anhydride was replaced with phthalic anhydride in an equimolar amount. The glass transition temperature of the resin (D) thus obtained was measured and found to be 65°C. Also, the results of measuring the molecular weight distribution of this material are Mw = 9300, Mn =
3700, Mw/Mn=2.5, 150℃, 2160g
The MI value was 58. Toner was prepared using the above resin (D) in exactly the same manner as in Example 1.
(D) was produced. Comparative Example 2 Example 1 except that 83 g of isophthalic acid, 54 g of maleic anhydride, and 62 g of ethylene glycol were charged.
A polyester resin was produced in exactly the same manner.
This polyester resin contained 2.7 equivalents per 1000 g and had a number average molecular weight of 3000. Furthermore, the above resin was polymerized in exactly the same manner as in Example 1. As a result, stirring became difficult during the process, and the mixture completely gelled, making it impossible to produce the desired toner. Comparative example 3 216 g of isophthalic acid, 89 g of phthalic anhydride,
Neopentyl glycol 208g, maleic anhydride
4.9 g was reacted at 200-220° C. for 4 hours under N ₂ flow. The acid value at that time was 82. This polyester resin contained 0.10 equivalent per 1000 g, and its number average molecular weight was 560. Next, a toner resin (E) was produced in exactly the same manner as in Example 1. The glass transition temperature of the resin (E) thus obtained was measured to be 49°C. Also, the results of measuring the molecular weight distribution of this material are Mw = 3800, Mn = 760,
Mw/Mn=4.8, and the MI value at 150℃2160g is
It was over 100. Toner was prepared using the above resin (E) in exactly the same manner as in Example 1.
(E) was produced. Comparative Example 4 Isophthalic acid was placed in a four-necked flask equipped with a stirrer, condenser, inert gas inlet tube, and thermometer.
1660g, maleic anhydride 49g, bisphenol A
3,793 g of 2 mole adduct of propylene oxide of
15mgKOH/g, hydroxyl value 35mgKOH/g molecular weight approx.
2200 unsaturated polyester was obtained. 50 g of this polyester was dissolved in 450 g of styrene to form a solution. Put 1000g of pure water and 0.5g of polyvinyl alcohol into a reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen gas blowing tube, and after raising the temperature to 70℃, add 500g of the above polyester styrene solution and azobisisobutyronitrile. 0.25g was added dropwise over 1 hour. Thereafter, after reacting at 70°C for 1 hour, the temperature was raised to 80°C in 30 minutes, and the reaction was completed in 10 hours. After removing the suspending agent by washing with water, a dry granular graft polymer was obtained. The number average molecular weight of this polymer by GPC was 23,500, and the softening point by the ring and ball method was 140°C. A toner (F) was produced using the obtained resin (F) in exactly the same manner as in Example 1. Comparative Example 5 From 125 g of unsaturated polyester obtained in Comparative Example 4 and 375 g of styrene, in the same manner as in Comparative Example 4,
A graft polymer was obtained with a number average molecular weight of 19,500 by GPC and a softening point of 154°C by the ring and ball method. A toner (G) was produced using the obtained resin (G) in exactly the same manner as in Example 1. Comparative Example 6 216g of isophthalic acid, 104g of phthalic anhydride,
208g of neopentyl glycol under _N2 flow
The reaction was performed at 200 to 220°C for 4 hours, then at 240°C for 20 hours, and further under 50 mmHg for 5 hours.
The acid value at the end of the reaction was 4.7, and Mw = 31500 at that time.
Mn=7680, Mw/Mn=4.1, glass transition temperature is 58℃, MI value of 2160g at 100℃ is 0.1
It was below. A toner (H) was produced using the obtained resin (H) in exactly the same manner as in Example 1. Evaluation of the electrophotographic toner of the present invention: The fixing properties and offset properties of the toners of Examples 1 to 7 and Comparative Examples 1 and 3 obtained as described above were examined using a high-speed copying machine at 70 sheets per minute. As a result, in the example of the present invention, both the fixing and offset properties were good even after 10,000 sheets were continuously copied, whereas in the case of Comparative Examples 1 and 3, offset occurred from the second sheet.
It turned out that the image quality was poor and could not be used. In the case of Comparative Examples 4 and 5, offset occurred from the 10th and 15th sheets, respectively, resulting in poor image quality and it was found that they could not be used. In the case of Comparative Example 6, the fixing properties were insufficient from the first sheet, and it peeled off immediately when rubbed with a fingernail, making it unusable.

Claims (1)

[Claims] 1 Number average molecular weight 1000 to 1000 with double bonds derived from 0.05 to 2.0 equivalents of unsaturated dibasic acid per 1000g
4000 unsaturated polyester resin is further polymerized by heating or in the presence of a polymerization initiator and substantially in the absence of a vinyl monomer, which is solid at room temperature and has a weight average molecular weight to number average molecular weight ratio of 5.
A resin for electrophotographic toner characterized by the above characteristics.