JPH032300B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel resin for electrostatic image developing toner, and more particularly, to a heat treatment that can be used to develop electrostatic latent images formed in electrostatic photography, electrostatic printing, electrostatic recording, etc. This invention relates to a resin for dry toner suitable for roller fixing. In image forming methods such as electrophotography and electrostatic recording, the toner image visualized in the development process is generally transferred to transfer paper or other support and then fixed using a heat roller fixing method. This heat roller fixing method is excellent in terms of high thermal efficiency, and is particularly capable of high-speed fixing, making it suitable for fixing in high-speed copying machines. However, with the development of the information society in recent years, demands for higher quality images, faster recording speeds, and long-term preservation of records have increased in the fields of electrophotography, electrostatic printing, and electrostatic recording. There is a growing demand for improved properties of toners used in developing latent images. Improving these properties is also required for heat roll fixing toners, and for this reason, research has been carried out on various toner resins in order to satisfy the above-mentioned required properties with the resins used in the toners. It has been done. For example, in 1983, it was discovered that polyester resin could be used as a heat roller fixing toner.
It is disclosed in various publications such as JP-A No. 25420, JP-A No. 53-17496, JP-A No. 55-49305, JP-A No. 55-38524, JP-A No. 57-37353, and JP-A No. 58-11952, but it has not been proposed in the past. All polyester resins for toners have advantages and disadvantages, and no one has yet been found that fully satisfies the above requirements for improved properties. That is, polyester resin has the advantage that it is easy to set the minimum fixing temperature low, it can cope with higher speed copying machines, and it can reduce power consumption. In addition, when polyester resin is melted, it has good wettability to toner additives and supports such as transfer paper, making it easy to disperse carbon black, colorants, magnetic powder, charge control agents, etc. It also has the advantage of being superior in quality. Furthermore, since the polyester resin itself has negative chargeability,
Although it has several advantages, such as uniform and stable charging without the use of a charge control agent or with a small amount of charge control agent, it also has serious disadvantages that are unacceptable for toner resins, such as the following: have. (1) Resistance to plasticizers, etc. for vinyl chloride resin (hereinafter referred to as plasticizer resistance) is low, so the object to be copied may be an article made of soft vinyl chloride that contains a plasticizer (for example, a book covered with soft vinyl chloride, etc.) ) has the disadvantage of contaminating the article if it comes into contact with it. Furthermore, if vinyl chloride resin coated electric wires used for wiring inside a copying machine are contaminated with toner containing carbon, it may cause electrical leakage, shoots, etc. (2) Poor storage stability, toner tends to cause caking or blocking due to storage, transportation, and temperature atmosphere inside copying machines after production, and magnetic toner in particular has a high specific gravity, so caking is even more likely to occur. There are drawbacks. (3) During fixing, part of the toner that makes up the image is transferred to the surface of the heat roller, and this is likely to be transferred again to the transfer paper that is sent next, causing the so-called offset phenomenon to occur, staining the image. There are drawbacks. The present inventors have conducted extensive research aimed at eliminating the drawbacks (1) to (3) above and providing a resin suitable for heat roll fixing toners that satisfies the above-mentioned required characteristics as completely as possible. The present invention was completed by discovering that a partially crosslinked polyester resin having specific physical properties produced under specific conditions satisfies the above objectives. Thus, according to the invention: (i) consisting essentially of dicarboxylic acid units (A) and glycol units (B), (a) at least 80 mol % of dicarboxylic acid units (A);
are aromatic dicarboxylic acid units, at least 30 mol % of the aromatic dicarboxylic acid units consist of terephthalic acid units and the remainder consist of isophthalic acid units, and (b) at least 80 mol % of the glycol units (B) are symmetrical. symmetrical glycol units, at least 30 mol% of the symmetrical glycol units consist of ethylene glycol units, a number average molecular weight of at least 1500, and an acid value of
To the OH-terminated polyester polymer of 20 mgKOH/g or less, trivalent or tetravalent in an amount equivalent to 0.1 to 0.5 mol per 1 mol of the above dicarboxylic acid unit (A).
(ii) Then, the crosslinkable polyester polymer is reacted with a dicarboxylic acid, an acid anhydride thereof, or a mixture thereof to form a crosslinkable polyester polymer, and (ii) the crosslinkable polyester polymer is reacted with a dicarboxylic acid unit (A) at a concentration of 0.007 to 0.07 per mole of the dicarboxylic acid unit (A).
The acid value obtained by reacting with a polyepoxide having 2 to 4 epoxy groups in one molecule in a mole-equivalent amount is 20 to 150 mlKOH/g.
Accordingly, there is provided a resin for electrostatic image developing toner having a glass transition temperature of 60 to 80°C and a softening point (according to the ring and ball method) of 100 to 200°C. The toner resin provided by the present invention has a low fixing temperature (a temperature that does not cause the transfer paper to wrap around the heat roll, has no low-temperature offset, and provides sufficient fixing strength), and has a high offset temperature itself. It has a high generation temperature, has excellent storage stability and plasticizer resistance, and is strongly, uniformly and stably charged without the use of charge control agents, and has good miscibility with colorants, magnetic carriers, etc. This provides a toner that has good tribocharging properties, exhibits stable charging properties during use, provides clear, fog-free images, and is resistant to shearing and frictional forces experienced in electrostatic recording devices. Moreover, it has extremely excellent performance as a resin for heat roller fixing toner, in that it does not cause filming on the toner contact member and has good fluidity, transferability, and cleaning properties. . Note that the term "number average molecular weight" used in this specification means a value calculated by creating a calibration curve using a polystyrene standard by gel permeation chromatography (GPC). The polyester polymer serving as the base of the toner resin of the present invention is an OH-terminated polyester substantially composed of dicarboxylic acid units (A) and glycol units (B). In such a polyester polymer, at least 80 mol%, preferably 90 to 100 mol% of the dicarboxylic acid units (A) constituting the polyester polymer are aromatic dicarboxylic acid units, and at least It is important that 30 mol%, preferably 50 mol% or more, is occupied by terephthalic acid units and the remainder consists of isophthalic acid units. If the proportion of the aromatic dicarboxylic acid unit in the dicarboxylic acid unit (A) is less than 80 mol%, the final resin will be dioctyl phthalate (hereinafter referred to as DOP) or dibutyl phthalate (hereinafter referred to as DBP).
There is a tendency for resistance to plasticizers and caking resistance to decrease. When the proportion of terephthalic acid units in the aromatic dicarboxylic acid units is lower than 30 mol%, the crystallinity of the resulting polyester polymer is relaxed,
Although high temperature offset resistance is improved, plasticizer resistance and storage stability tend to decrease, making it difficult to obtain a resin with a good balance in these properties. The above polyester polymer I can optionally contain aliphatic dicarboxylic acid units in a proportion of 20 mol% or less of the dicarboxylic acid units, thereby reducing the low temperature of the toner formed using the resin of the present invention. However, as the ratio of aliphatic dicarboxylic acid units increases, the resistance of the final resin to plasticizers such as DOP and DBP and caking resistance tend to decrease. Be looked at. Examples of aliphatic dicarboxylic acid units that can be used include one or more units derived from aliphatic dicarboxylic acids such as succinic acid, maleic acid, fumaric acid, adipic acid, and hydrogenated phthalic acid. . On the other hand, the selection of the glycol unit (B), which is another structural unit constituting the polyester polymer used in the present invention, is also important, and in the present invention, at least 80 mol% of the glycol unit (B) has symmetry It must be a glycol unit.
When the proportion of symmetrical glycol units is less than 80 mol%, the crystallinity of the resulting polyester polymer is relaxed and the high temperature offset resistance is improved;
Plasticizer resistance, storage stability, etc. tend to decrease, making it difficult to obtain a resin with a good balance in these properties, which is undesirable. Examples of symmetrical glycol units include alkylene glycols such as ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, neopentyl glycol, and 1,6-hexanediol; diethylene glycol, triethylene glycol, polyethylene glycol,
Polyalkylene glycol such as polypentamethylene glycol; 1,4-dimethylolbenzene,
Included are one or more units derived from 1,4-cyclohexanedimethanol, bisphenol A, hydrogenated bisphenol A, bisphenol A-ethylene oxide adduct, and the like. Furthermore, in the present invention, it is important that at least 30 mol% of the symmetrical glycol units are ethylene glycol units, and if the content of the ethylene glycol units is less than 30 mol%,
Disadvantages such as resistance to plasticizers such as DOP and DBP and decreased storage stability are likely to occur.
Therefore, the ethylene glycol units preferably account for 40 mol% or more of the symmetrical glycol units. The polyester polymer used in the present invention may contain an asymmetric glycol unit, if necessary, for the purpose of further improving the physical properties such as low temperature fixability and abrasion resistance of the resin of the present invention. can. Such asymmetric glycol units include, for example, 1,2-propylene glycol,
Examples include one or more units derived from 1,2-butylene glycol, 1,3-butylene glycol, polypropylene glycol, and the like. However, if the content of these asymmetric glycol units increases too much, the physical properties such as plasticizer resistance and storage stability of the final resin will tend to decrease. It should be kept at 20 mol% or less of the unit (B), preferably 10 mol% or less. The polyester polymer having the above-mentioned structure includes a dicarboxylic acid or an ester-forming derivative thereof (for example, a halide, a lower alkyl ester, a phenyl ester, etc.) corresponding to the dicarboxylic acid unit described above, and a glycol unit corresponding to the glycol unit described above. It can be produced by polymerizing a glycol or its ester-forming derivative (for example, an ester with a lower carboxylic acid) under conditions that form an OH-terminated polyester by a condensation polymerization method known per se. . For example, a dehydration reaction is performed with a dicarboxylic acid and an excess amount of glycol in the presence of an esterification catalyst (para-toluenesulfonic acid, dibutyltin oxide, orthodibutyl titanate, tetrabutyl titanate, etc.), followed by a polycondensation reaction under high vacuum. or transesterification catalysts (e.g. zinc acetate, lead acetate,
(lead oxide, dibutyltin oxide, tetrabutyl titanate, etc.), lower alkyl esters such as dicarboxylic acid methyl esters or phenyl esters, and 1.5 times the mole or more of glycol or dicarboxylic acids and glycol lower fatty acid esters (e.g. diacetate esters). Melt polymerization method (for example, chloroform,
Any method may be used, such as a method of manufacturing by solution polymerization using dichloroethane, trichloroethane, etc.). The polyester polymers so produced should have a number average molecular weight of at least 1500, preferably in the range 2000 to 30000. Furthermore, the polyester polymer used in the present invention is OH-terminated, provided that the hydroxyl value is
It is important that the content is 75mgKOH/g or less. If the hydroxyl value of the polymer exceeds 75 mgKOH/g, the number average molecular weight will be less than 1500, and the portions that did not participate in branching in the process of obtaining the polyester polymer will have disadvantages such as decreased storage stability and filming phenomenon. Generally, the hydroxyl value of the polymer is 3 to 75 mg.
It is preferable to keep it within the range of KOH/g. Also,
Although the polymer may contain some terminal COOH groups, the acid value of the polymer is generally 20 mg
KOH/g or less, preferably 10 mgKOH/g or less. According to the present invention, the polyester polymer described above can be converted into a branched crosslinkable polyester polymer by reacting it with a trivalent or tetravalent carboxylic acid or its acid anhydride or a mixture thereof. . The trivalent or tetravalent carboxylic acid (hereinafter referred to as polyvalent carboxylic acid) that can be reacted with the polymer may be of either aliphatic type or aromatic type; Examples of acids include aliphatic polycarboxylic acids such as 1,2,4-butanetricarboxylic acid and 1,2,4-cyclohexanetricarboxylic acid; trimellitic acid, pyromellitic acid, pyromellitic acid monomethyl ester, naphthalenetricarboxylic acid,
Aromatic polyhydric carboxylic acids such as naphthalenetetracarboxylic acid and benzophenonetetracarboxylic acid are mentioned, and each of these can be used alone or as a mixture of two or more types. Further, these polyhydric carboxylic acids may be reacted with the polyester polymer in the form of acid anhydrides. In addition, the amount of polyhydric carboxylic acid or its acid anhydride to be used for the polyester polymer is based on the dicarboxylic acid unit (A) in the polymer.
The amount can range from 0.1 to 0.5 mol, preferably from 0.1 to 0.4 mol per mol. The branched polyester polymer modified with polyhydric carboxylic acid as described above generally has a molecular weight of 1,500 or more,
Preferably, it has a number average molecular weight in the range of 2,000 to 10,000, and it is generally desirable to have an acid value in the range of about 40 to 200 mg KOH/g, preferably 50 to 150 mg KOH/g. Furthermore, the polyester polymer is generally at least 50°C, preferably at 55°C, from the viewpoint of low temperature fixability, storage stability, etc. of the toner resin of the present invention.
It is desirable to have a glass transition temperature Tg within the range of ~80°C. In this specification, "glass transition temperature" Tg means
This is the temperature at the intersection of the baseline extension line on the low temperature side measured by a differential scanning calorimeter (DSC) and the tangent to the straight line of the heat absorption section. The above-mentioned polyester polymer has a carboxyl group introduced by reaction with a polyhydric carboxylic acid or its acid anhydride at the end, and has 2 to 2 carboxyl groups in one molecule.
It is partially crosslinked by reaction with a polyepoxide containing four epoxy groups. The polyepoxide used as a crosslinking agent has 2 to 4 epoxy groups in one molecule, and both low molecular weight and high molecular weight types can be used, but the polyepoxide generally has a molecular weight of 180 to 3000. , preferably in the range of 300 to 2000, and in terms of epoxy equivalent weight, generally 90 to 2000, preferably
Those having an epoxy equivalent weight within the range of 140 to 1400 are preferred. Specific examples of such polyepoxides include: bisphenol A type epoxy resin, novolak type epoxy resin, ethylene glycol diglycidyl ether, glycerin triglycidyl ether, pentaerythritate tetraglycidyl ether, hydroquinone glycidyl ether, N,N
- diglycidylaniline, tetrakis 1,1,
2,2(p-hydroxyphenyl)ethane tetraglycidyl ether, etc. Furthermore, the ratio of polyepoxide to the crosslinkable polyester polymer mentioned above can be varied over a wide range depending on the type of polyepoxide used, the desired degree of crosslinking, etc.; Unit (A)
0.007 to 1 mole of the unit (A) based on the amount of
It is advantageous to use 0.07 mol, preferably within the range from 0.01 to 0.06 mol. In this crosslinking reaction, the resulting resin of the present invention has a softening point (softening point measured by the ring and ball method described in JIS K2207; the same shall apply hereinafter) of 100 to 200°C, preferably
It can be carried out until the temperature is within the range of 120 to 190°C. Further, the resin of the present invention prepared as described above is 20 to 150 mgKOH/g, preferably 30 to 150 mgKOH/g.
It has an acid value within the range of 130mgKOH/g, and a glass transition temperature (Tg) of 60 to 80°C, preferably 60 to
Can be within the range of 75℃. Therefore, the toner resin provided by the present invention exhibits various excellent properties as described below.
It is suitably used as a binder for heat roller fixing type dry toner. (a) It has high resistance to plasticizers for vinyl chloride resins, and even if the object to be copied comes into contact with a soft vinyl chloride article containing a plasticizer, the article will not be contaminated. (b) Even when left at a temperature of 50°C for more than a week, no defects such as blocking or caking occur, and the product has excellent storage stability. (c) Although the fixable temperature is low, the offset generation temperature is high, the fixable temperature range is wide, and the offset phenomenon is less likely to occur. (d) It can withstand shearing and frictional forces received in a copying machine, does not cause filming on toner contact members, and has excellent fluidity, transferability, cleaning performance, etc. (e) It has good tribocharging properties, shows stable charging properties at all times during use, does not cause toner scattering, and provides clear, fog-free images. The production of toner using the resin of the present invention can be carried out according to methods known per se, and usually,
When the resin of the present invention is blended with a colorant and, if necessary, a property improver to make a magnetic toner,
A toner can be produced by mixing magnetic powder together with or in place of a colorant, sufficiently melting and kneading, and pulverizing. When preparing the toner as described above, the resin of the present invention is added as a binder in an amount that does not significantly affect the effect of the resin, for example, 30 parts by weight or less per 100 parts by weight of the resin of the present invention. Other binder resins, such as polyester resins other than those of the present invention, and other resins commonly used for heat roller fixing may also be used. Coloring agents include carbon black, Nigron dye (CI No. 50415B), and aniline blue (CI No.
50405), Calco Oil Blue (CINo.azoec
Blue3), Chrome Yellow (CINo.14090), Ultramarine Blue (CINo.77103), DuPont Oil Red (CINo.26105), Quinoline Yellow (CI
No.47005), methylene blue chloride (CINo.
52015), Phthalocyanine Blue (CINo.74160),
Malachite Green Oxalate (CINo.
42000), lamp black (CI No. 77266), rose bengal (CI No. 45435), and mixtures thereof. These colorants must be contained in a sufficient proportion to form a visible image of sufficient density, and are usually contained in a proportion of about 1 to 20 parts by weight per 100 parts by weight of the binder. The magnetic material may be a ferromagnetic metal or alloy such as iron, cobalt, or nickel, including ferrite and magnetite, or a compound containing these elements, or a material that does not contain a ferromagnetic element but is subjected to appropriate heat treatment. Alloys that become ferromagnetic, such as manganese-copper-aluminum,
Mention may be made of a type of alloy called Heusler alloy containing manganese and copper, such as manganese-copper-tin, or chromium dioxide, among others. These magnetic substances are uniformly dispersed in the binder in the form of fine powder with an average particle size of 0.1 to 1 micron. Its content is generally 20 to 70 parts by weight per 100 parts by weight of toner.
Preferably it can be 40 to 70 parts by weight. In addition, the toner prepared using the resin of the present invention may optionally contain a substance having mold releasability, such as higher fatty acids or metal salts of higher fatty acids, as a property improver for the purpose of further improving offset resistance. , natural or synthetic waxes, higher fatty acid esters or partially saponified products thereof, alkylene bis fatty acid amides, fluororesins, silicone resins, etc. may also be blended. The amount incorporated can generally be 1 to 10 parts by weight per 100 parts by weight of the binder. Next, the present invention will be further explained with reference to Examples.
In the examples, "parts" and the blending ratio of each component are parts by weight unless otherwise specified. Example 1 253 parts of dimethyl terephthalate, 136 parts of dimethyl isophthalate, 186 parts of ethylene glycol,
The mixture was added to a 4-neck round bottom flask equipped with a thermometer, stainless steel stirrer, glass nitrogen inlet tube, and down-flow condenser. Next, nitrogen gas was introduced into the flask to maintain an inert atmosphere inside the reactor, the temperature was raised, and 1.4 parts of tetrabutyl titanate was added with stirring. While removing methanol produced by the transesterification reaction, the reaction temperature was gradually raised and maintained at 240°C to complete the transesterification reaction. Next, the pressure was reduced to 1 mmHg or less at 240° C. over 1 hour, and a polycondensation reaction was further carried out for 4 hours to obtain a polyester. This polyester has dicarboxylic acid units (A) with 100 mol% of aromatic dicarboxylic acid units consisting of 65 mol% of terephthalic acid units and 35 mol% of isophthalic acid units.
and glycol unit (B) consisting of 100 mol% of ethylene glycol, and has a number average molecular weight of 18,000, an acid value of 1 mgKOH/g or less, and a hydroxyl value of 6 mg.
It had a characteristic value of KOH/g. 77 parts of trimellitic anhydride (0.2 mol per 1 mol of the above carboxylic acid unit (A)) was added to the above polyester.
The mixture was added at 240° C. under a nitrogen atmosphere at normal pressure and reacted for 1 hour to obtain polyester. This polyester had an acid value of 95 mgKOH/g, a number average molecular weight of 2000, and a glass transition point of 57°C. Subsequently, the diglycidyl ether of bisphenol A 20
(0.021 mol per 1 mol of dicarboxylic acid unit (A) above) and reacted for 1 hour to obtain an acid value of 85 mg.
A polyester resin for toner with KOH/g, Tg 65°C, and softening point 180°C was produced. Although the reaction of this polyester resin was further extended for 1 hour, the reaction did not proceed any further and no change was observed in the physical property values of the polyester resin. After preliminarily dispersing 95 parts of the polyester resin for toner and 5 parts of carbon black obtained above using a Henschel mixer (manufactured by Mitsui Miike Seisakusho Co., Ltd.), a co-directional twin-screw kneading extruder (manufactured by Ikegai Iron Works Co., Ltd.) was used. Heat kneading is performed, and after cooling, it is pulverized using a jet mill (manufactured by Nippon Neumatic Industries Co., Ltd.), and then the average particle size is determined using an air classifier (manufactured by Nippon Neumatic Industries Co., Ltd.).
A 12μ toner was produced. A developer was prepared by mixing 10 parts of this toner with 90 parts of iron powder carrier (TEFV250/400 manufactured by Nippon Tetsuko Co., Ltd.), and the toner characteristics were evaluated using the test method below. As a result, the fixing temperature limit was 135°C. It was an excellent toner with a low offset generation temperature of 250°C and a wide fixing temperature range. Furthermore, the storage stability and plasticizer resistance showed very good results with no abnormalities observed at all. (1) Lower limit fixing temperature and offset occurrence temperature An electrostatic charge image formed by ordinary electrophotography was developed using an electrophotographic copying machine DC-191 manufactured by Sanda Kogyo Co., Ltd., and the toner image was transferred onto plain paper. . The transfer paper on which this toner image has been formed is fixed using a fixing roll whose surface is made of Teflon and a pressure roll whose surface is made of silicone rubber, by varying the temperature of the fixing roll, and then adjusting the minimum fixing temperature and offset. The generated temperature was measured. (2) Storage stability Put 100g of toner in a cylindrical container with a diameter of 6cm.
After being left in an atmosphere at 50° C. for one week, blocking and caking of the toner particles were observed. ○: Phenomena such as blocking and caking do not occur at all, and almost no change is observed in fluidity. Δ: Slight blocking occurs, but it is easily loosened by shaking the container, and fluidity is restored. No practical problems. ×: Caking occurs, and the caked particles do not loosen even when the container is shaken, and remain as clumps. (3) Plasticizer resistance Put toner particles in DOP and DBP,
The state of the particles was observed after 24 hours at 35°C. ◎: No change observed, excellent plasticizer resistance. Good: Blocking occurs in the toner particles, but the toner particles are not softened and are not a problem in practice. x: The toner particles swell or partially dissolve, causing a blocking phenomenon, and the particles become soft. Examples 2 to 4 and Comparative Examples 1 to 2 Polyester resins for toners were produced in substantially the same manner as in Example 1 using the formulations shown in Table 1 below.

【table】

[Table] Toners were produced in the same manner as in Example 1 using the toner polyester resins of the Examples and Comparative Examples obtained above, and the toner properties were evaluated. The evaluation results are shown in Table-2. The results of measuring the physical properties of the polyester polymer and the polyester resin for toner are also shown in Table 2.

【table】

[Table] As is clear from the evaluation results in Table 2 above, the toner of Example 2, which is the present invention, is composed of aromatic dicarboxylic acid containing terephthalic acid units in a relatively small proportion of 35 mol%. Since the toner is manufactured using a polyester polymer obtained from the base polymer and a polyester resin for toner obtained from the base polymer, the plasticizer resistance and storage stability are slightly inferior compared to the toner of Example 1. However, the offset generation temperature was as high as 245°C, and good toner properties were exhibited. Contrary to Example 2, Example 3 exhibited extremely good toner properties in terms of plasticizer resistance and storage stability, probably because the proportion of terephthalic acid units in the polyester polymer was high. In Example 4, the entire aromatic dicarboxylic acid in the base polymer polyester polymer was composed of terephthalic acid, and the toner exhibited extremely excellent plasticizer resistance. However, because the number average molecular weight of the polyester polymer was relatively low at 3000, the offset generation temperature was 230°C.
Compared to Examples 1 and 2, the values were slightly lower. On the other hand, the toner of Comparative Example 1, which was based on a polyester polymer in which the proportion of terephthalic acid in the aromatic dicarboxylic acid was outside the range of the present invention, had an offset generation temperature of 230°C.
Although the temperature was high, the toner had poor storage stability. In addition, in Comparative Example 2, the ratio of aromatic dicarboxylic acid in the dicarboxylic acid component constituting the polyester polymer was 70 mol%, which is lower than the range of the present invention, so the toner had poor plasticizer resistance and was not practical. It did not have any. Examples 5 to 7 and Comparative Examples 3 to 4 Polyester resins for toners were produced in substantially the same manner as in Example 1 using the formulations shown in Table 3 below.

[Table] Using each of the polyester resins for toners of Examples and Comparative Examples obtained above, toners were made in the same manner as in Example 1, and the toner characteristics were evaluated. The results are shown in Table 4. At the same time, the results of measuring the physical properties of the polyester polymer and the polyester resin for toner are also shown in Table 4.

[Table] As is clear from the evaluation results in Table 4 above, the toner of Example 5 was a well-balanced toner with excellent various performances. In Example 6, there was a tendency for the plasticizer resistance and storage stability of the toner to slightly decrease, probably because the proportion of ethylene glycol in the glycol component constituting the polyester polymer was relatively small at 35 mol%. However, the toner did not impede practical use and had excellent performance in terms of minimum fixing temperature, offset generation temperature, etc. In Example 7, there was a tendency for physical properties such as plasticizer resistance and storage stability to deteriorate, probably because the polyester polymer contained asymmetric glycol units at a ratio of 20 mol% among the glycol components. However, it was not to the extent that it would hinder practicality. In addition,
The toner of Comparative Example 3, in which the base polymer was a polyester polymer produced by further increasing the amount of asymmetric glycol units to 30 mol%, showed a tendency to decrease in plasticizer resistance and storage stability, and could no longer be put to practical use. It was something I couldn't get. The toner of Comparative Example 4 showed excellent performance in high-temperature offset resistance, probably because the content of ethylene glycol in the symmetrical glycol component constituting the polyester polymer was 20 mol%, which was outside the scope of the present invention. However, the plasticizer resistance and storage stability deteriorated, making it impractical. Examples 8-9 and Comparative Examples 5-7 Formulas in Table 5 below (excluding Comparative Example 7)
A polyester resin for toner was produced in substantially the same manner as in Example 1. In the formulation shown in Comparative Example 7, a gel-like polyester resin for toner was produced only by continuing the polycondensation reaction of the polyester polymer without using a polyepoxide crosslinking agent.

【table】

【table】

[Table] Using the polyester resins for toners of each of the Examples and Comparative Examples obtained above, toners were made in the same manner as in Example 1, and the toner properties were evaluated. The evaluation results are shown in Table-6.

[Table] As is clear from the results in Table 6 above, the toner of Example 8 has a minimum fixing temperature of 135°C and an offset generation temperature of 240°C, and the temperature difference between the two, that is, the fixable temperature range is extremely large, at 105°C. It was a highly practical toner with excellent plasticizer resistance and storage stability. Furthermore, the toner of Example 9 also has a fixable temperature range.
The temperature was even wider at 110°C, and as in Example 8, it was an excellent toner with high practicality. In Comparative Examples 5 and 6, when modifying a polyester polymer into a crosslinkable polyester polymer, 3 to 3
Because a dicarboxylic acid was used instead of a tetravalent carboxylic acid or its anhydride, the resulting polyester resin for toner had low temperature characteristics such as glass transition temperature and softening point, and as a result, the polyester resin produced from the polyester resin was low. These toners had a narrow fixable temperature range and had extremely poor storage stability, making them impractical. The polyester resin for toner of Comparative Example 7 was manufactured without using a polyepoxide crosslinking agent, so no crosslinking occurred in the resin, and it had thermal properties of a glass transition temperature of 52°C and a softening point of 165°C. It was scarce. Therefore, although toner manufactured from this polyester resin has excellent plasticizer resistance, the offset generation temperature is low at 210°C.
The fixable temperature range was as narrow as 95° C., and in addition, the toner had poor storage stability, making it difficult to say that it was a practically desirable toner. Comparative Example 8 Terephthalic acid 332 was added to the same reactor as in Example 1.
1 part, 77 parts of ethylene glycol, and 189 parts of hydrogenated bisphenol A, and placed in an oil bath.
Introduce nitrogen gas to maintain an inert atmosphere inside the reaction vessel and raise the temperature. Add 2 parts of dibutyltin oxide with stirring and heat at 180°C to 200°C for 3 hours and then at 230°C to 200°C for 3 hours.
The esterification reaction was carried out at 240°C while removing the produced water. The reaction was continued until the acid value reached 30 mgKOH/g while measuring the acid value every hour to produce a polyester polymer. The polyester polymer had a number average molecular weight of 1800 and a hydroxyl value of 20 mgKOH/g. 98 parts of pyromellitic anhydride was added to this polyester polymer and reacted for 1 hour to obtain an acid value of 150 mg.
A polyester polymer with KOH/g and a glass transition point of 50°C was obtained, and then 28 parts of diglycidyl ether of bisphenol A was added at 250 to 260°C, and after one hour of reaction, the acid value was 123 mgKOH/g and the glass transition point was 123 mgKOH/g. A polyester resin for toner with a temperature of 56°C and a softening point of 160°C was produced. Using the polyester resin obtained above, Example 1
A toner was produced in the same manner, and the toner properties were then evaluated. As a result, the acid value of the polyester polymer that is the base polymer was 30 mgKOH/g, which is high and out of the range of the present invention, and this may have an adverse effect on the glass transition temperature of the polyester resin finally obtained. Also, the offset generation temperature was low, the fixable temperature range was narrow, the storage stability was poor, and the performance could not be put to practical use. Example 9 Polyester resin for toner manufactured in Example 1
65 parts, magnetite fine powder (EPT manufactured by Toda Kogyo Co., Ltd.)
-1000) was used to produce a magnetic toner having an average particle size of 12μ in the same manner as in the example. The resulting toner is placed in a developer equipped with a rotatable stainless steel sleeve with a magnet in the center and a doctor blade to charge the toner and form a uniform layer of magnetic toner on the sleeve. Developing the electrostatic latent image on the support member and transferring it onto transfer paper,
Next, heat roller fixing was performed in the same manner as in Example 1. This toner had good fluidity and formed a uniform toner layer on the stainless steel sleeve, giving a clear and fog-free image. I also made 10,000 continuous copies, but there was no change in image quality. Furthermore, the storage stability of this toner was investigated in the same manner as in Example 1, and no defects such as caking were observed.
No deterioration in image quality was observed. In this example, the lower limit temperature for fixing the toner with the heat roll was 145°C, and the temperature at which offset occurred was 250°C.
℃, it had extremely excellent temperature characteristics.

Claims (1)

[Claims] 1 (i) Dicarboxylic acid unit (A) and glycol unit (B)
consisting essentially of (a) at least 80 mole % of dicarboxylic acid units (A);
are aromatic dicarboxylic acid units, at least 30 mol % of the aromatic dicarboxylic acid units consist of terephthalic acid units and the remainder consist of isophthalic acid units, and (b) at least 80 mol % of the glycol units (B) are symmetrical. symmetrical glycol units, at least 30 mol% of the symmetrical glycol units consist of ethylene glycol units, a number average molecular weight of at least 1500, and an acid value of
To the OH-terminated polyester polymer of 20 mgKOH/g or less, trivalent or tetravalent in an amount equivalent to 0.1 to 0.5 mol per 1 mol of the above dicarboxylic acid unit (A).
(ii) Then, the crosslinkable polyester polymer is reacted with a dicarboxylic acid, an acid anhydride thereof, or a mixture thereof to form a crosslinkable polyester polymer, and (ii) the crosslinkable polyester polymer is reacted with a dicarboxylic acid unit (A) in an amount of 0.007 to 0.07 per mole of the dicarboxylic acid unit (A).
The acid value obtained by reacting with a polyepoxide having 2 to 4 epoxy groups in one molecule in a mole-equivalent amount is 20 to 150 mgKOH/g.
A resin for electrostatic image developing toner having a glass transition temperature of 60 to 80°C and a softening point (according to the ring and ball method) of 100 to 200°C.