JPH03627B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a positively chargeable electrophotographic toner. More specifically, the present invention relates to a positively chargeable electrophotographic toner having excellent vinyl chloride resistance and charging properties. Recently, with the development of computer peripherals, the development of high-speed printers has become active.
Many of these printers generally employ an electrophotographic method using a laser beam as an optical exposure system. Therefore, the toner used in this type of high-speed printer needs to be positively chargeable due to the characteristics of the electrophotographic photoreceptor used, and the use of such toner is likely to increase in the future. . By the way, the handling of the copies made by the above-mentioned printers has diversified, and for example, the copies are often used or stored in cases made of soft PVC sheets. Depending on this type of usage, plasticizers such as dioctyl phthalate (DOP) contained in the PVC sheet gradually ooze out and plasticize the toner fixed on the copy document. This causes the inconvenience that the toner adheres and damages the copied document. If the copied document is particularly an important document such as a certificate, it is undesirable for the contents to be damaged, and therefore it is required that the toner does not adhere to the PVC sheet (hereinafter referred to as PVC resistance).
Against this background, there is a demand in the art for the development of positively chargeable electrophotographic toners with good vinyl chloride resistance. Conventionally, styrene-acrylic resins have been used as binder resins for electrophotographic toners, regardless of whether they are positively charged or negatively charged, but none of these resins are completely satisfactory in terms of PVC resistance. .
Furthermore, epoxy resins or polyester resins are also used as binder resins other than styrene-acrylic resins, and these exhibit good vinyl chloride resistance. However, epoxy resin-based toners are inferior in offset resistance, while polyester resin-based toners are excellent in fixing strength and offset resistance, but have poor positive charging characteristics. In this way, no matter which conventionally known resin is used, it is possible to have vinyl chloride resistance and positive charging characteristics, and to simultaneously satisfy the general performance requirements required for electrophotographic toners, such as offset resistance and fixing strength. At present, positively chargeable toner for electrophotography is not available. The inventors of the present invention focused their studies on polyester resin as a resin with relatively good performance among known resins for toner binders. As already mentioned, polyester resin toner has poor positive charging characteristics. Although the cause is difficult to elucidate in detail, it has been found that it is largely due to the number of carboxyl groups remaining in the polyester resin, that is, the acid value of the resin. Here, the term "good positive chargeability" means that the toner can have a sufficient amount of positive charge necessary for developing an electrostatic latent image. Known polyester resins for toners are different from highly condensable polyester resins such as polyethylene terephthalate (which cannot be used for toners due to fixing properties and crushability during toner production), and have a relatively high acid value. Therefore, it is impossible to provide a sufficient amount of positive chargeability simply by using a positive charge control agent such as nigrosine, which is commonly used as a component of positively chargeable toners, and the positive chargeability is poor. becomes. Based on this viewpoint, the inventors of the present invention conducted studies to develop a new polyester resin with excellent positive charging characteristics, and surprisingly found that The present inventors have discovered that the above object can be satisfied by using a toner containing a specific rosin-based polyester resin containing an amino alcohol component as a binder, and have completed the present invention. That is, the present invention provides a positively charging electrophotographic toner comprising a colorant dispersed in a binder resin, in which the binder resin includes (I) rosin glycidyl ester, () dicarboxylic acid or dicarboxylic acid anhydride, () general formula ( 1): (In the formula, A is an alkyl group or alkanol group having 1 to 4 carbon atoms, B is a hydrogen atom or a carbon number 1 to 4
an alkanol group, n is an integer of 1 to 4), and optionally () a polyfunctional epoxy compound, a trivalent or higher polybasic acid or its acid anhydride, and 3 which does not contain nitrogen. At least one crosslinking agent selected from the group consisting of polyhydric alcohols having a glass transition temperature of 50 to 90°C, which can be obtained by reacting a dihydric alcohol that does not contain nitrogen, or (V) a dihydric alcohol that does not contain nitrogen;
Gelation rate for xylene is 99% or less, acid value is 20
The present invention relates to a positively chargeable electrophotographic toner containing the following rosin compound. The positively chargeable electrophotographic toner of the present invention is characterized by excellent vinyl chloride resistance and positive chargeability.
Compared to conventional polyester resins, the rosin-based polyester resin of the present invention has superior positive charging characteristics because its acid value is considerably lower, and because the amino alcohol component is uniformly introduced into the polyester resin through an esterification reaction. Therefore, the toner prepared from the polyester has excellent positive charging characteristics because there is no non-uniform distribution of the amount of charge. As a result, when the toner composition of the present invention is made into a developer, the charge level rises well, no fogging phenomenon occurs, and there are no problems around the developing device due to scattered toner. Further, the toner of the present invention has excellent heat resistance, fixing properties, offset resistance and printing durability. Furthermore, since filming and poor cleaning do not occur, there is an advantage that no damage is caused to the photoreceptor. The rosin glycidyl ester (I) used in the present invention can be prepared by heating and reacting rosin and epihalohydrin in the presence of an alkaline substance such as an organic amine. Examples of the rosin used include gum rosin,
Examples include natural rosins such as uddrosin and tall oil rosin, hydrogenated rosins obtained by modifying these rosins, and disproportionated rosins. Also,
Naturally, the active ingredients of rosin, such as abietic acid, dehydroabietic acid, dihydroabietic acid, pimaric acid, and isopimaric acid, are also included. The organic amines are preferably tertiary amines or onium salts thereof, and specific examples of the tertiary amines include triethylamine, dimethylbenzylamine, methyldibenzylamine, tribenzylamine, dimethylaniline, and dimethylcyclohexylamine. , methyldicyclohexylamine, tripropylamine, tributylamine,
Examples include N-phenylmorpholine, N-methylpiperidine, and pyridine. Specific examples of onium salts of tertiary amines include tetramethylammonium chloride, tetramethylammonium bromide, benzyltriethylammonium chloride, allyltriethylammonium bromide, tratylammonium chloride, methyllioctylammonium chloride, and trimethylamine hydrochloride. kind,
Examples include triethylamine hydrochloride and pyridine hydrochloride. The dicarboxylic acids or dicarboxylic acid anhydrides (hereinafter referred to as dicarboxylic acids) used in the present invention include orthophthalic acid, isophthalic acid, terephthalic acid, endomethylenetetrahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, Hexahydrophthalic acid, methylhexahydrophthalic acid, maleic acid, fumaric acid, succinic acid, adipic acid, azelaic acid, sebacic acid, alkenyl succinic acid having 8 to 18 carbon atoms, alkyl succinic acid having 8 to 18 carbon atoms and their acid anhydrides. Examples of the crosslinking agent () used in the present invention include the following compounds. Examples of the polyfunctional epoxy compound include an epoxy resin which is a condensate of bisphenol A and epihalohydrin, and rosin diepoxide or rosin triepoxide which is a reaction product of acrylated rosin or fumarized rosin and epihalohydrin. The rosin used for the polyepoxide of the rosin is the same as that used for the rosin glycidyl ester. Examples of trivalent or higher polybasic acids or their anhydrides include trimetic acid, pyromellitic acid, and acid anhydrides corresponding thereto. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. In the present invention, if necessary, a dihydric alcohol () may be used to form a rosin-based polymer compound. That is, the dihydric alcohol is the other component (I),
It is used to adjust the glass transition point of the rosin-based polymer compound obtained by reacting () and () and to improve the fixing properties. The nitrogen-free dihydric alcohol (V) used in the present invention is not particularly limited, and includes, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,2-
Butanediol, 1,3-butanediol, 1,
4-butanediol, bisphenol A, hydrogenated bisphenol A, ethoxylated bisphenol A,
Examples include propoxylated bisphenol A. The amount of dihydric alcohol to be used may be appropriately determined in consideration of the glass transition point of the rosin-based polymer compound to be obtained, and can usually be used in an amount of up to 70 mol% of the rosin glycidyl ester. In addition, the amino alcohol essential for positively charging the toner composition of the present invention is an amino alcohol represented by the general formula (1), such as monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine. , N-monomethylethanolamine, and the like. The amount of such amine to be used is appropriately determined in consideration of positive charging characteristics, and is usually preferably 30% by weight or less based on the polyester. If more than this amount is added, the positive charging characteristics cannot be further improved, and the resulting resin will instead have an amine odor, resulting in no particular benefit. The method for producing the rosin-based polymer compound used in the present invention involves simultaneously charging the rosin glycidyl ester, the dicarboxylic acids, and the crosslinking agent and reacting them by heating, or by heating the rosin glycidyl ester and the dicarboxylic acids, and causing the reaction. A crosslinking agent may be added during the reaction or after the reaction is completed, and the reaction may be further advanced by heating. In that case, the molar ratio of rosin glycidyl ester and dicarboxylic acid used is preferably 1:1. However, this does not apply when dihydric alcohol is used. This will be discussed later. On the other hand, the amount of the crosslinking agent to be used must be appropriately and carefully determined since it has a significant effect on the physical properties, particularly the molecular weight and molecular weight distribution, of the resulting toner binder resin. The amount of the polyfunctional epoxy compound used among the crosslinking agents may be determined by considering the number of functional groups of the compound, that is, the epoxy equivalent,
Normally, when the total number of moles of rosin glycidyl ester and dicarboxylic acids is 1 mole, for example, for fumarized rosin triglycidyl ester,
The amount is 0.005 to 0.07 mol, preferably 0.005 to 0.04 mol. In the case of commercially available bisphenol type epoxy resins, 0.005 to 0.14 mol, preferably 0.005 to 0.14 mol,
It is preferable to set it at 0.07 mol. Similarly, polyhydric carboxylic acids or polyhydric alcohols also take into consideration the number of their functional groups, and are usually 0.005 to 0.3 mol, preferably 0.005 in the case of trihydric acids, relative to the total number of moles of rosin glycidyl ester and dicarboxylic acids. Use within the range of ~0.15 mol. However, in the case where the amino alcohol to be reacted in the present invention is trivalent, for example, triethanolamine or diethanolamine, if the amount added is sufficient, polymerization and partial gelation can be achieved with this alone, so crosslinking is not necessarily required. It is not necessary to add an agent. Of course, it goes without saying that a trivalent amino alcohol and a crosslinking agent may be used in combination. In addition, in the present invention, the binder resin of the toner of the present invention can be obtained in high yield regardless of the presence or absence of a solvent during the reaction, but in order to smoothly distill the water produced during the reaction out of the system, a refluxing solvent is used. It is also possible to use The solvent is determined in consideration of azeotropic properties with the produced water, non-reactivity with rosin glycidyl esters, dicarboxylic acids, and crosslinking agents, and specific examples include toluene and xylene. In the present invention, the reaction temperature and reaction time are appropriately determined in consideration of the yield of the product, but when an acid anhydride is used as the dicarboxylic acid, the reaction temperature is 100 to 250°C, preferably 130 to 180°C. C, 150 to 300 C, preferably 180 to 260 C when a dicarboxylic acid is used, and in either case, the reaction time is preferably 0.5 to 10 hours, preferably 1 to 8 hours. If a solvent is used during the reaction, the solid content can be obtained by distilling it off under reduced pressure. By the production method described above, the novel rosin-based polymer compound used in the present invention can be obtained in high yield. In addition, the end point of the reaction in the present invention is
It can be easily determined by appropriately measuring the gelation rate with respect to xylene. Note that the gelation rate with respect to xylene referred to herein means the insolubility rate with respect to xylene. The rosin-based polymer compound obtained in the present invention has a glass transition point of 50 to 90 in consideration of properties as a positively charged electrophotographic toner, that is, blocking resistance, offset resistance, heat resistance, and fixing property. °C,
It is preferable that the gelation rate with respect to xylene is 99% or less and the acid value is 20 or less. That is, if the glass transition point is less than 50°C, the heat resistance will be poor, while if it exceeds 90°C, the fixing property will be poor. If the gelation rate exceeds 99%, it is difficult to produce a rosin-based polymer compound, and workability during toner production (for example, kneading with carbon black) is poor. Further, even if the amount of amino alcohol added is increased, if the acid value of the resin exceeds 20, the desired positive charging property cannot be obtained. In the present invention, conventionally known colorants can be used as they are. Such colorants include, for example, carbon black, nigrosine dye, aniline blue, alcohol blue, chrome yellow, ultramarine blue, monoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, monastral. Examples include retsudo. In addition, the toner of the present invention may include, for example, (i) metal powders such as iron, manganese, nickel, cobalt, and chromium, (ii) iron alloys such as ferrite and magnetite, and alloys or compounds such as cobalt, nickel, and manganese; ) Other conventionally known ferromagnetic materials can also be blended. Furthermore, the toner of the present invention may be used in combination with a conventional binder resin for toners within a range that does not depart from the purpose of the present invention. Next, the positively chargeable electrophotographic toner of the present invention will be described with reference to reference examples and examples, but the present invention is not limited to these examples. Reference Example 1 (Production of disproportionated rosin glycidyl ester) Disproportionated rosin (acid value 162, softening point 79) with a purity of 87% (13% is unsaponifiable) was placed in a No. 5 Kolben equipped with a stirring device and a reflux condenser. C), 2000 g of epichlorohydrin, and 1 g of benzyltrimethylammonium chloride were added, and the mixture was reacted at 80° C. for 4 hours. Then, at the same temperature, add granular sodium hydroxide.
160 g was added in portions, the temperature was raised to 100°C, and the reaction was continued for an additional 2 hours. After filtering the precipitated salt, unreacted epichlorohydrin was distilled off from the filtrate using a rotary evaporator, and volatile components were completely removed under conditions of 2 mmHg and 120°C to obtain the title pale yellow oil (yield 97.2%). ) was obtained. The acid value of this substance is 0.
The epoxy equivalent was 425, and the purity was 84% in terms of epoxy equivalent. Reference Examples 2 to 4 In Reference Example 1, the starting material rosin was gum rosin (purity 91%, acid value 169, softening point 75°C), hydrogenated rosin (purity 89%, acid value 165, softening point 74°C), Thor Oil rosin (purity 87%, acid value 163, softening point 73℃)
Various resins were obtained by carrying out the reaction in the same manner except that each of these resins was changed and used in Reference Examples 2 to 4 in turn. The acid value of Reference Example 2 is 0, the epoxy equivalent is 436.5,
The purity was 82.1%. Reference example 3 has an acid value of 0, an epoxy equivalent of 431.6, and a purity of 83.5%.
Reference example 4 has an acid value of 0 and an epoxy equivalent of 445.5.
The purity was 80.0%. Reference Example 5 1748 g of disproportionated rosin glycidyl ester obtained in Reference Example 1, 170 g of triethylene glycol, 345 g of triethanolamine,
Add 1035g of terephthalic acid and 100g of xylene,
Reaction was carried out at 220°C for 8 hours under a nitrogen stream. The water produced during that time was removed azeotropically. Acid value is approx.
After confirming that the pressure had reached 10, the reaction was carried out under reduced pressure of 70 mmHg. During this time, the viscosity of the reaction solution increased. Sampling was carried out from time to time, and when some insoluble matter was formed in xylene, the reaction was stopped and taken out. The resulting resin had a glass transition point of 68°C, a gelation rate of 48% in xylene, and an acid value of 5.2. Reference Example 6 The reaction was carried out in the same manner as in Reference Example 5 except that diethanolamine was used in place of triethanolamine and trimellitic anhydride was also used as a crosslinking agent. Reference Example 7 In Reference Example 5, diethanolamine was used instead of triethanolamine, trimethylolpropane was used as the crosslinking agent, and a propylene oxide adduct of bisphenol A (manufactured by NOF Corporation, DB-400) was used as the dihydric alcohol. The reaction was carried out in the same manner except that each was used. Reference Example 8 The reaction was carried out in the same manner as in Reference Example 5, except that the glycidyl ester obtained in Reference Example 3 was used, phthalic anhydride was used as the acid component, and neopentyl glycol was used as the dihydric alcohol, and a gel was produced. I took it out just before. Reference Example 9 A reaction was carried out in the same manner as in Reference Example 5 using the composition shown in Table 1. The acid value was 30 because the proportion of the acid component used was large. The above results are summarized in Table 1.

[Table] Examples 1 to 4 and Comparative Example 1 Reference Examples 5 to 8 (Examples 1 to 4) and Reference Example 9
(Comparative Example 1) Carbon Black MA
5 parts by weight of #100 (manufactured by Mitsubishi Chemical Industries, Ltd.), 3 parts by weight of the nigrosine dye Bontron N-06 (manufactured by Orient Chemical Industries, Ltd.), and Viscol 550P (manufactured by Sanyo Chemical Industries, Ltd.). Two parts by weight were thoroughly mixed and kneaded using an extruder. Then, after cooling, it was coarsely pulverized to a size of 1 cm square, finely pulverized with a jet mill, and then classified with an air classifier to obtain toners 1 to 4 with a particle size range of 5 to 20 μm and an average particle size of 13 to 14 μm. (Examples 1 to 4) and Toner 5 (Comparative Example 1) were obtained. Next, 3 parts by weight of each of these toners and 100 parts by weight of iron powder carrier (manufactured by Nippon Tetsuko Co., Ltd., TEF-V) were mixed to sufficiently triboelectrically charge the toners.
A CdS binder-based photoreceptor was negatively charged and placed in a copying machine, and a printing durability test was conducted. The results are shown in Table 2.

【table】

[Table] Furthermore, the images produced with each of these toners 1 to 5 were brought into contact with a PVC sheet (manufactured by Mitsui Toatsu Chemical Co., Ltd.) containing 30% DOP and heated at 60℃ and 100g/cm ² for 24 hours. When we investigated DOP migration (vinyl chloride resistance) when stored for a period of time, none of the images adhered to the vinyl chloride sheet.

Claims (1)

[Scope of Claims] 1. A positively charged electrophotographic toner comprising a colorant dispersed in a binder resin, wherein the binder resin includes (I) rosin glycidyl ester, () dicarboxylic acid or dicarboxylic acid anhydride,
and () General formula (1): (In the formula, A is an alkyl group or alkanol group having 1 to 4 carbon atoms, B is a hydrogen atom or a carbon number 1 to 4
alkanol group, n is an integer of 1 to 4), the glass transition point is 50 to 90°C, the gelation rate with xylene is 99% or less, and the acid value is 20 (KOHmg). /g) A positively chargeable electrophotographic toner comprising a rosin compound having the following properties. 2. In a positively charging electrophotographic toner comprising a colorant dispersed in a binder resin, the binder resin includes (I) rosin glycidyl ester, () dicarboxylic acid or dicarboxylic acid anhydride, () general formula (1): (In the formula, A is an alkyl group or alkanol group having 1 to 4 carbon atoms, B is a hydrogen atom or a carbon number 1 to 4
alkanol group, n is an integer of 1 to 4), and () polyfunctional epoxy compounds, trivalent or higher polybasic acids or their acid anhydrides, and trivalent or higher valent polybasic acids that do not contain nitrogen. The glass transition temperature obtained by reacting at least one crosslinking agent selected from the group consisting of polyhydric alcohols is 50 to 90 °C,
Gelation rate for xylene is 99% or less, acid value is 20
(KOHmg/g) or less. 3. In a positively charged electrophotographic toner comprising a colorant dispersed in a binder resin, the binder resin includes (I) rosin glycidyl ester, () dicarboxylic acid or dicarboxylic acid anhydride, () general formula (1): (In the formula, A is an alkyl group or alkanol group having 1 to 4 carbon atoms, B is a hydrogen atom or a carbon number 1 to 4
The glass transition temperature obtained by reacting an amino alcohol represented by an alkanol group (n is an integer of 1 to 4) and a dihydric alcohol not containing nitrogen is 50 to 90 °C,
Gelation rate for xylene is 99% or less, acid value is 20
(KOHmg/g) or less.