JP2585553B2 - Toner for electrostatic latent image development - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrostatic latent image developing toner used for electrophotography, electrostatic recording, electrostatic printing and the like.

(Prior art)

In electrophotography, an electrostatic latent image is generally formed on a photoreceptor by various means using a photoconductive substance, and then the latent image is developed using a toner. After transferring the image, the image is fixed by heating or solvent vapor to obtain a copy.

As a method for visualizing the electrostatic latent image using toner, a magnetic brush method, a cascade developing method, a powder method, and the like are known. In any of the developing methods, fixing of the toner image is an important step. Needless to say.

By the way, at present, as such a fixing method, a method of softening or melting a thermoplastic resin contained in a toner by heating such as hot roll fixing, atmosphere fixing, and flash fixing to adhere to paper is commonly used. In particular, a heat roll fixing system having a high heat supply efficiency is most commonly used in terms of power saving and high-speed capability.
However, in the case of this hot roll fixing, the hot roll and the toner in the heat-melted state are in direct contact with each other at the time of fixing, so that a part of the toner adheres to the hot roll surface, and this contaminates the next transfer paper or the like. A so-called offset phenomenon occurs.

As a method of preventing this offset phenomenon, for example,
A method is known in which silicone oil or the like is applied to the surface of a heat roll to reduce the adhesive force between the heat roll and the toner.However, this method requires a step of applying silicone oil or the like, so that a fixing device is required. There were difficulties, such as a complicated structure.

As another method, a method of imparting an anti-offset property to the toner itself has also been proposed. For example, the glass transition temperature (Tg) and the molecular weight of the binder resin in the toner are increased to improve the melt viscoelasticity of the toner. Methods are also known. However, when the offset phenomenon is improved by such a method, there is a problem that the fixing property becomes insufficient and the fixing property at low temperature, that is, the low-temperature fixing property required for power saving and high speed operation is inferior. .

In general, in order to improve the low-temperature fixability of a toner, it is necessary to reduce the viscosity of the toner at the time of melting and increase the adhesion area with a fixing base material.
It is required to reduce Tg and molecular weight.

That is, since the low-temperature fixability and the offset prevention performance have opposite sides, it is very difficult to develop a toner that simultaneously satisfies these functions.

On the other hand, with the rapid development of stencil printing and the development of demand for vinyl chloride products in recent years, various demands have been made for copy products fixed with toner.

For example, stencil printing in the past was done by handwriting on a master paper with an iron brush, etc., which is called `` slicing '', but recently the master paper is overlaid on the original and the difference in absorbance due to the density of the original is used. In addition, a method of melting a portion corresponding to a black portion of an original of a thin film of polyester or the like formed on a master paper by a flash light and performing plate making at once is becoming popular.

In the stencil printing method, when a toner to which a toner is fixed is used as a document, the toner fixed in the stencil making process is melted, and the toner is fused to a perforated portion of the film, and the printed image is blurred. Is generated.

In order to eliminate such drawbacks, for example,
No. 3354 discloses a toner consisting of a vinyl polymer which is appropriately cross-linked by adding a cross-linking agent and a molecular weight regulator.
There are two types of toners: α, β unsaturated ethylenic monomer as a constituent unit, and a toner whose molecular weight distribution is widened so that the ratio of the weight average molecular weight to the number average molecular weight is 3.5 to 40. Has proposed a blend type toner combining Tg, molecular weight, gel content and the like.

Certainly, the toner according to these proposals has a fixable temperature between the lower limit of fixing temperature (the lowest temperature at which fixing can be performed) and the offset temperature (the temperature at which offset starts to occur), compared to a toner composed of a single resin having a narrow molecular weight distribution. Although the range is expanded, when sufficient offset prevention performance is imparted, the fixing temperature cannot be sufficiently lowered, and conversely, there is a problem that the offset prevention performance becomes insufficient when low-temperature fixing performance is emphasized. .

Further, instead of these vinyl resins, JP-A-57-20855
As described in No. 9, a toner obtained by crosslinking a polyester resin and further adding an offset preventing agent has been proposed. This product is excellent in both low-temperature fixability and offset prevention performance, but there is no satisfactory result because the toner is fused to hot stencil master paper, and various release agents, which are offset prevention agents, are added to the toner. However, there is a problem that the effect of preventing toner fusion to the master paper is not sufficiently exhibited.

Furthermore, Japanese Patent Application Laid-Open No. 54-114245 discloses that a low-molecular weight low-melting polyester resin or an epoxy resin containing 50 to 95 parts by weight and a macromolecular vinyl resin having a weight-average molecular weight of 500,000 or more contains low-temperature fixability and offset prevention. Toners satisfying both performances have been proposed, but since the difference in melt viscosity used is too large, a toner showing a good dispersion state even after long-time melt-kneading with strong shearing force is obtained. Can not do.

In general, when resins having poor compatibility are blended, these resins are generally assumed to have a sea-island structure. This sea-island theory is based on, for example, plastics, 13 , No. 9, 1P (1961).
2). Improving the dispersibility means reducing the size of the islands. For example, when performing melt kneading, it is said that the closer the melt viscosity of the resin to be blended is, the better the dispersibility is. According to a transmission electron microscope observation of the dispersion state of the toner shown in Example 1 of JP-A-54-114245, styrene / butadiene resin is present in a sea-like polyester as a very large island, The dispersion of carbon black is also non-uniform, and each toner particle is not in a uniformly dispersed state.Moreover, when this toner is mixed with an iron powder carrier and the charge amount distribution of the toner is measured, it shows an unusually wide distribution. Fogging also occurred when making copies. When a stencil master is made using paper on which this toner has been fixed,
A large amount of toner was fused to the master paper, and the stamp image was unclear.

JP-A-59-107359 discloses that a polycondensate composed of a polyfunctional monomer is 5 to 45% by weight and a polymer composed of a vinyl monomer is used.
95-55 parts by weight, 20-60% by weight of polyfunctional monomer
Discloses a toner using a resin that is a monomer having three or more functional groups.However, this polymer has a three-dimensional structure, so that the melt viscoelasticity is increased and low-temperature fixing, which is an advantage of the polycondensate, is disclosed. Has the disadvantage that the properties are not sufficiently exhibited.

In addition, in order to improve the dispersibility of the polyester resin and the vinyl resin, a method has been proposed in which a common segment is introduced into both to form a graft copolymer. The functions of both performance and low-temperature fixability cannot be fully utilized.

On the other hand, contamination of vinyl chloride products due to toner is caused by plasticizers such as dioctyl phthalate (DOP) and dibutyl phthalate (DBP) contained in soft vinyl chloride migrating to the toner side, lowering the viscosity of the toner, and causing the toner to become chlorinated. Occurs by adhering to vinyl products.

Conventionally, styrene and styrene- (meth) acrylate copolymers have been generally used as binder resins for toners for developing electrostatic latent images, but these resins are plasticizers contained in vinyl chloride. The above process causes toner contamination of the soft vinyl chloride product due to the good compatibility with the vinyl chloride product.

There are several proposals for prevention of toner contamination of vinyl chloride products, but all of them have been shown to have the effect of preventing contamination of vinyl chloride products, but have been applied to other important qualities as toner, especially low-temperature fixability and stencil master paper. Did not improve the toner fusion prevention effect. For example, JP-B-55-10906 and JP-A-59-166965 propose to introduce a hydrophilic group into a binder resin. Although the predetermined effects are recognized, all have a serious drawback that the toner charge amount changes due to environmental (temperature, humidity) fluctuations, and the image quality deteriorates accordingly.

Further, JP-A-59-162564 discloses a homopolymer or copolymer of a (meth) acrylate having an alkyl group having 3 or less carbon atoms, or a copolymer with styrene (styrene monomer unit 30% by weight or less). It has been proposed that acrylates be used, but in the case of acrylates, not only homopolymers, but also when styrene is copolymerized, if the styrene content is 30 wt% or less, the Tg of the copolymer will be low and the toner will coagulate and solidify during storage. In the case of methacrylic acid esters, the storage stability is good due to the high Tg, but sufficient heat fixability cannot be obtained.

〔Purpose〕

INDUSTRIAL APPLICABILITY The present invention has an excellent anti-offset performance and a good low-temperature fixability, does not fuse in a stencil master making process, and has an excellent anti-contamination property for vinyl chloride products for electrostatic latent image development. It is intended to provide a toner.

〔Constitution〕

According to the present invention, in a toner for developing an electrostatic latent image containing at least a binder resin and a colorant, a weight average molecular weight of 8,000 to 16000 as a binder resin, and a glass transition temperature of 5
0-65 ° C polyester resin and weight average molecular weight 200,000-50
10,000, gel content 15-50% and glass transition temperature 55-70
A toner for developing an electrostatic latent image, characterized by using a styrene-acrylic acid methyl ester copolymer at a temperature of ° C.

As described above, the toner for developing an electrostatic latent image according to the present invention uses a specific polyester resin and a specific styrene-acrylic acid methyl ester copolymer as the binder resin, so that the toner has an anti-offset property and a low temperature. It has excellent fixability, prevents stencil printing masters from being fused to perforations in the stencil making process, and is excellent in stain resistance of vinyl chloride products. Further, the toner according to the present invention has excellent charging uniformity and can maintain stable performance even when environmental conditions are different.

 Hereinafter, the present invention will be described in more detail.

In the present invention, as one of the essential components of the binder resin, weight average molecular weight 200,000 to 50, gel content 15 to
A styrene-acrylic acid methyl ester copolymer having 50% and a glass transition temperature (Tg) of 55 to 70 ° C is used.

In general, a toner using a styrene-acrylic copolymer as a binder is considered to easily adhere to and contaminate a soft vinyl chloride product, but the styrene and acrylic acid methyl ester copolymer used in the present invention is other general Unlike the styrene-acrylic copolymers described above, the soft vinyl chloride product is extremely excellent in stain resistance and has very little phenomenon of fusing to a stencil master paper.

The reason for this is not clear, but the SP value of the methyl acrylate copolymer (dissolution parameter), especially the SP value of the hydrogen bonding component, is the SP value of the plasticizer contained in the vinyl chloride product.
It is considered that the soft vinyl chloride product has excellent stain resistance because it is far away from the value. In addition, the acrylic acid methyl ester homopolymer has a higher glass transition temperature (Tg) than other alkyl acrylate homopolymers.
It is a hard resin with high molecular flexibility and low molecular flexibility, and it retains its rigidity even when copolymerized with styrene, so it can prevent the stencil printing master paper from fusing. It seems possible.

The function of preventing the fusion of the toner in the stencil master is increased by achieving high viscoelasticity and high molecular weight of the styrene-acrylic acid methyl ester copolymer under a high temperature range, and further crosslinks the styrene-acrylic acid methyl ester copolymer. This further improves the function of preventing fusion.

Further, the present invention requires that a specific polyester resin be used together with the styrene-methyl acrylate copolymer as the binder resin.

The polyester resin used in the present invention has a weight average molecular weight.
It has a glass transition temperature of 8000 to 16000 and a glass transition temperature of 50 to 65 ° C.

Such a polyester resin can be easily obtained by a polycondensation method, has a strong adhesive strength due to a polar group effect in the molecule, and further includes an SP value (melting parameter) in the vinyl chloride effect. Because it is far from the SP value of the plasticizer, it has excellent stain resistance of vinyl chloride resin products.

The polyester resin used in the toner of the present invention is composed of a dihydric alcohol as shown in the following group A and a dibasic acid as shown in the group B, and further, as shown in the group C. A trihydric or higher alcohol or carboxylic acid may be added as the third component.

Group A: ethylene glycol, triethylene glycol,
1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol,
1,4-butenediol, 1,4-bis (hydroxymethyl)
Cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3)
-2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0)-
Polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane and the like.

Group B: maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid,
Linoleic acid or esters of these with acid anhydrides or lower alcohols.

Group C: trihydric or higher alcohols such as glycerin, trimethylolpropane, and pentaerythritol; trihydric or higher carboxylic acids such as trimellitic acid and pyromellitic acid;

Further, in the present invention, if the performance of the toner is not impaired, for example, 20% by weight or less in all binders,
Other known thermoplastic resins, for example, epoxy resin, polyamide resin, urethane resin, phenol resin, butyral resin, styrene-butadiene resin, styrene-methacrylic resin, or styrene-alkyl acrylate having an alkyl group having 2 or more carbon atoms An ester resin or the like may be mixed.

As mentioned above, when incompatible resins are blended,
These resins usually have a sea-island structure, but in the present invention, it is preferable that the sea structure is a styrene-methyl acrylate copolymer and the island structure is a polyester resin.

That is, the sea, which is a continuous layer, has an internal cohesive force at the time of melting the toner, imparts an adhesive function to the low-melting island, and exerts the advantages of both resins. In this case, the low-melting polyester resin, which is an island, melts first at the time of heat fixing, assists plasticization of the entire toner, and is extruded onto the toner surface when pressed by a fixing roll. The fixing effect is more than the amount.

In order to obtain such a sea-island structure, in the present invention, the polyester resin preferably contains 20 to 45% by weight in the binder resin.

With such a configuration, the internal cohesive force of the whole toner is increased, and the offset prevention performance and the toner fusion prevention performance on the stencil printing master can be further improved.

Even if the sea is made to have a low melting property and the island is made highly viscoelastic, the interaction between the two is small even if the island is expected to have a filler effect, and a sufficient filler effect cannot be obtained. Can not do it.

In the present invention, it is desirable to uniformly disperse the polyester resin and the styrene-methyl acrylate copolymer so as to make the charge amount of each toner particle as uniform as possible.

This is because there is a toner charge amount area that is most easily developed in the development process, so that when the charge amount distribution of the toner is wide, development selection occurs, and when development is performed repeatedly, toner not used for development is accumulated, and This is because fog and bleeding occur to cause deterioration of image quality.

Further, the polyester resin used in the present invention has a stronger negative polarity than the styrene-acrylic acid methyl ester copolymer, and unless each toner particle is in a uniform dispersion state,
The charging of the toner becomes uneven, and the distribution of the charging amount cannot be narrow.

From such a viewpoint, as the polyester resin in the present invention, those having a weight-average molecular weight of 8000 to 16000 and a glass transition temperature (Tg) of 50 to 60 ° C., and a styrene-methyl acrylate copolymer as a weight-average molecular weight 20
Those having a molecular weight of 10,000 to 500,000, a gel content of 15 to 50%, and a glass transition temperature (Tg) of 55 to 70 ° C are used.

If the ratio is outside the above range, the uniform chargeability, low-temperature fixability, toner fusion prevention effect of the stencil printing master, and ability to prevent contamination of the vinyl chloride product become weak.

Further, as described above, the polyester resin used in the present invention has a stronger negative polarity than the styrene-methyl acrylate copolymer.However, the oxidation is controlled to 15 or less, and preferably to 10 or less. The volume distribution can be narrowed.

The molecular weight and glass transition temperature (T
g), gel content and acid value were calculated by the following measurement methods.

(1) Molecular weight The molecular weight was measured by gel permeation chromatography under the following conditions.

The sample was dissolved in THF (tetrahydrofuran) at a concentration of 0.1% by weight, measured at a temperature of 20 ° C. at a flow rate of 1 ml / min, and the molecular weight was determined by a calibration curve using a monodisperse polystyrene standard sample.

(2) Glass transition temperature (Tg) The glass transition temperature (Tg) was measured by a differential scanning calorimeter.

(3) Gel content 1) Add 50 ml of THF to 0.01 g of sample and stir for 3 hours.

2) The contents are suction filtered through a glass filter lined with Celite # 545.

3) The glass filter after filtration was dried under reduced pressure and weighed to obtain (A).

4) The weight of the glass filter before filtration was defined as B, and the gel content was calculated by the following equation.

(4) Acid value The sample was dissolved in a neutralized toluene / acetone mixed solvent, titrated with a pre-specified alcoholic solution of N / 10 potassium hydroxide, and calculated from the neutralized amount.

As the colorant used in the toner of the present invention,
The following optional pigments and dyes can be selected.

Black pigments Carbon black, acetylene black, lamb black, aniline black.

Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, hange yellow G, Hanser yellow 10G, benzine yellow G, benzidine yellow GR, quinoline yellow rake,
Permanent yellow CG, tartrazine rake.

Orange pigment Red lead graphite, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK.

Red pigment Bengala, Cadmium Red, Lead Tan, Cadmium Mercury Sulfide, Permanent Red 4R, Lysole Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake,
Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.

Purple pigment Manganese purple, fast violet B, methyl violet lake.

Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalonoanine blue, partially chlorinated phthalocyanine blue, first sky blue, indanthrene blue B
C.

Green pigments: chrome green, chromium oxide, pigment green B, malachite green lake, fanal yellow green.

White pigment Zinc white, titanium oxide, antimony white, zinc sulfide.

Extender Pigment barite powder, barium carbonate, clay, silica, white carbon, talc, amina white, various dyes (basic, acidic dispersion, direct dyes, etc.) Nigrin, methylene blue, rose bengal, quinoline yellow, ultraman blue, etc.

Further, as a regulator of the polarity and charge amount of the toner, glocine, a monoazo dye, zinc hexadecyl succinate,
Alkyl esters or alkylamides of naphthoic acid,
Strongly polar substances such as nitrohumic acid, N, N'-tetramethyldiaminebenzophenone, N, N'-tetramethylbenzidine, triazine, salicylic acid metal complex and the like can be used as a charge control agent.

When a magnetic toner is used, ferromagnetic elements and alloys and compounds containing them may be used as the magnetic powder. Specific examples of such magnetic powders include iron, cobalt, magnetite, hematite, and ferrite. And materials conventionally known as magnetic materials, such as alloys and compounds of nickel, manganese, and the like, and other ferromagnetic alloys.

These magnetic materials are added as fine powder having an average particle size of about 0.1 to 5 microns, preferably 0.1 to 1 micron, in a proportion of about 1 to 60% by weight, preferably 5 to 40% by weight of the toner.

Further, as described above, since the toner of the present invention has high melt viscoelasticity, an offset phenomenon does not occur in hot roll fixing, but if necessary, a known release agent, for example, various waxes, low molecular weight Polypropylene, polyethylene and the like may be contained. Furthermore, in order to improve properties such as fluidity and cleaning properties of the toner, silica,
Titanium oxide, alumina, silicon carbide, zinc oxide, metal salts of higher fatty acids, fine powder of hard resin, and the like may be added and mixed.

The toners of the present invention are made by any of the well-known toner mixing and grinding methods.

In order to use the toner of the present invention by a cascade developing method, a magnetic brush developing method, a C-shell developing method, or the like,
The toner should have an average particle size, expressed as a percentage by weight, of less than about 30 microns, and preferably between about 4 and 20 microns for optimal results.

Coated and uncoated carriers used in cascade development, magnetic brush development, C-shell development, and the like are well known, however, such that toner powder adheres to and surrounds the carrier particles. The carrier particles may be formed of any suitable material so long as the toner particles acquire a charge of opposite polarity to that of the carrier particles when the carrier particles are brought into intimate contact with the toner powder.

Accordingly, the toners of the present invention can be used in combination with conventional carriers to develop an electrostatic positive image on any suitable electrostatic latent image bearing surface, including conventional photoconductive surfaces. You.

〔effect〕

As described above, the toner for electrostatic latent images of the present invention uses a specific polyester resin and a specific styrene-acrylic acid methyl ester copolymer as the binder resin, and thus has an anti-offset property and a low-temperature fixing property. In addition, the stencil master is prevented from fusing to the perforations in the stencil making process, and the vinyl chloride product is excellent in stain resistance. Further, the toner according to the present invention has excellent charge uniformity and can maintain stable performance even when environmental conditions are different.

〔Example〕

 Hereinafter, the effects of the present invention will be specifically described with reference to examples.

Example 1 Polyoxyethylenated bisphenol A and terephthalic acid having a weight average molecular weight of about 6000, 9000, 12000, 150
A polyester resin of 00, 18000 was prepared. In addition,
The Tg of this polyester resin was adjusted to 55 ° C. and the acid value was adjusted to 3.

Next, benzoyl peroxide and divinylbenzene were added to a styrene monomer and an acrylic acid methyl ester monomer, and a weight average molecular weight of 350,000 and a gel content were obtained by a suspension polymerization method.
A styrene-acrylic acid methyl ester copolymer (St / MA) having a Tg of 60 ° C. and 30% was obtained.

35 parts by weight of the above five types of polyester resin and 65 parts St / MA
Parts by weight, 10 parts by weight of carbon black, 1 part by weight of nigrosine dye, and 4 parts by weight of low molecular weight polypropylene (Viscol 550P, manufactured by Sanyo Chemical Industries, Ltd.) were mixed and melt-kneaded for 1 hour by a two-roll mill. After cooling, the mixture was coarsely pulverized by a rotoplex, finely pulverized by a jet mill pulverizer, and classified by an air classifier to obtain a toner having a volume average particle diameter of 11 μm. These toners were evaluated for vinyl chloride toner contamination, toner fusion to a stencil master, minimum fixing temperature (the latest temperature at which fixing is possible), offset temperature (temperature at which offset starts to occur), and charging uniformity. . Table 1 shows the results.

 The evaluation test was performed as follows.

(1) Image sample preparation Electrophotography using a developer prepared by mixing and stirring 30 parts by weight of 4 parts by weight of toner and 96 parts by weight of iron oxide powder carrier (TEFV 200/300 Nippon Iron Powder Co., Ltd.) for 30 minutes. Copy machine FT-8030
(Ricoh Co., Ltd.) created an image sample. The image sample was provided with a black portion of 10 mm × 50 mm, and the reflection density was set to 1.2.

(2) Contamination of vinyl chloride toner The image obtained in (1) was sandwiched between soft vinyl chloride sheets, and a weight of 1 kg was applied per A-4 size. Check for contamination. If it is contaminated, the reflection density of the contaminated portion on the tote corresponding to the black portion is measured with a Macbeth densitometer, and the value obtained by subtracting the reflection density of the portion without an image is defined as the vinyl chloride toner contamination. This value increases as the level of contamination increases, and becomes zero if the level is not contaminated.

(3) Stencil printing master toner fusing property The image obtained in (1) is set on a master, and a stencil printing machine RISOGRAPH FX7200 (Riso Kagaku Kogyo Co., Ltd.) performs plate making on a dry mode scale 0, and then an image sample. Remove.
The reflection density of a portion corresponding to a 10 mm × 50 mm black portion on the plate-making master is measured, and the value obtained by subtracting the reflection density of the portion having no image is defined as the stencil printing master toner fusing property. This value becomes larger as the fusion becomes more intense, and shows a value of about 0.02 if it is not contaminated. From print quality, 0.09 is an allowable limit.

(4) The minimum fixing temperature and the offset temperature are determined by the developer used for preparing the image sample and the copying machine.

However, the fixing device can change the fixing temperature (heat roll surface temperature) without applying silicone oil. The minimum fixing temperature of the toner to be fixed at a low temperature is 145.
It must be below ° C.

(5) Charging uniformity A blow-off device for measuring the toner charge amount is used (cage blow-off method).

Take 4g developer created in (1), 0.5Kg / cm and a blow-off at the ^second air pressure seek g / m-1 of toner, a blow-off an additional air pressure of 2.5 Kg / cm ² the developer after blow-off G / m-2 of the toner. G / m-1 and g / m-
The value obtained by dividing the difference from 2 by the average value is defined as charging uniformity. The larger the value, the larger the distribution of the charge amount, which is not preferable. Usually, the permissible limit is around 0.5.

Example 2 A polyester resin composed of polyoxyethylene bisphenol A and phthalic acid and having Tg of about 45 ° C, 50 ° C, 55 ° C, 60 ° C, 65 ° C and 70 ° C was prepared.

The weight average molecular weight of these polyester resins is
12000, oxidation was adjusted to 3. 35 parts by weight of each of these six types of polyester resin and the St / M prepared in Example 1
A was converted to a toner with the same formulation and conditions as in Example 1. This toner was evaluated in the same manner as in Example 1.
Table 2 shows the results.

Example 3 Polyester resins comprising polyoxyethylenated bisphenol A and terephthalic acid and having acid numbers of about 1, 3, 10, 30, and 80 were prepared. The weight average molecular weight of these polyester resins was adjusted to 12000, and Tg was adjusted to 55 ° C. 35 parts by weight of each of these five types of polyester resins and 65 parts by weight of St / MA prepared in Example 1 were converted into toners under the same prescription and conditions as in Example 1, and the same evaluation was performed. Table 3 shows the results.

Example 4 A polyester resin composed of polyoxyethylenated bisphenol A and terephthalic acid and having a weight average molecular weight of 12,000, Tg of 55 ° C. and an acid value of 3 was prepared.

Next, the polymerization of St / MA was carried out in the same manner as in Example 1, but the weight average molecular weight was reduced to about 15 by adjusting the polymerization temperature, the amount of benzoyl peroxide, and the amount of divinylbengun.
We obtained St / MA of 10,000, 250,000, 350,000, 450,000 and 550,000. The gel content of these five St / MAs is 30%, Tg
Was adjusted to 60 ° C.

35 parts by weight of the above polyester resin and 65 parts by weight of each of the five types of St / MA having a different molecular weight were converted to toners under the same prescription conditions as in Example 1, and the same evaluation was performed. Table 4 shows the results.

Example 5 Polymerization was carried out in the same manner as in Example 1 except that the amount of divinylbenzene used, the amount of benzoyl peroxide used, and the polymerization temperature were changed, and the gel content was about 10, 20, 30, 40, 50, and 60%.
Different kinds of St / MA were obtained.

The weight average molecular weight of these six St / MAs was about 350,000, T
g was adjusted to 60 ° C. 65% by weight of each of these 6 types of St / MA and polyester resin used in Example 4.
35 parts by weight was converted into a toner under the same prescription and conditions as in Example 1, and the same evaluation was performed. Table 5 shows the results.

Example 6 Polymerization was carried out in the same manner as in Example 1 except that the copolymerization ratio of styrene methyl acrylate was changed. The weight average molecular weight was 350,000, the gel content was 30%, and the Tg was 50, 55,
Six types of St / MA at 60, 65, 70 and 75 ° C were obtained. This Tg
65 parts by weight of each of the six types of St / MA and 35 parts by weight of the polyester resin used in Example 4 were converted to toners under the same formulation and conditions as in Example 1 and evaluated in the same manner. Table 6 shows the results.

Example 7 Polyester resin (weight average molecular weight 12000, Tg 55 ° C., acid value 3) used in Example 4 and St / MA used in Example 1
(Weight average molecular weight 350,000, gel content 30%, Tg60 ° C)
The toner was prepared under the same formulation and conditions as in Example 1 except that the compounding ratios were 10:90, 20:80, 30:70, 40:60, and 50:50. Table 7 shows the results.

Comparative Example 11 Styrene monomer and butyl methacrylate monomer (nBMA) having different polymerization initiator and chain transfer agent concentrations and degrees
The styrene-butyl methacrylate copolymer having a wide molecular weight distribution was obtained by polymerization while sequentially adding the above mixture. Weight average molecular weight (Mw) and number average molecular weight (M
The ratio Mw / Mn of n) was 4.6, Mn was 17,000, and Tg was 75 ° C. This St / nNMA was used as a binder resin, and 100 parts by weight of St / nBMA, 10 parts by weight of carbon black, 1 part by weight of a nigrosine dye, and 4 parts by weight of a low molecular weight polypropylene were mixed in the same manner as in Example 1. Was converted to toner. The obtained toner was evaluated in the same manner as in Example 1. Table 8 shows the results.
Shown in

Comparative Example 12 In the same manner as in Comparative Example 1, Mw / Mn was 4.6 and Mn was 1700.
St / nBMA having a Tg of 64 ° C. was polymerized, converted into a toner in the same manner as in Comparative Example 1, and evaluated. Table 8 shows the results.

Comparative Example 13 Polymerization was carried out in the same manner as in Comparative Example 1 except that divinylbenzene was added at the time of polymerization. Mw / Mn was 15.3, and Mn was 2
1000, Tg 74 ° C, St / nBMA with 10% gel content
Was polymerized into a toner in the same manner as in Comparative Example 1 and evaluated. Table 8 shows the results.

Comparative Example 14 Crosslinked, comprising polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, terephthalic acid and pentaerythritol, having a Tg of 65 ° C. and a chloroform-insoluble content of 17% by weight. 100 parts by weight of a polyester resin was used as a binder resin and converted into a toner in the same manner as in Comparative Example 1.
evaluated. Table 8 shows the results.

Comparative Example 15 63 parts by weight of a polyester resin (Tg 50 ° C., weight average molecular weight 6000) comprising bisphenol A and maleic anhydride,
Styrene-butadiene copolymer (weight average molecular weight 150
Comparative Example 1 using 27 parts by weight of a binder resin
In the same manner as in the above, the toner was evaluated. Table 8 shows the results.

Comparative Example 16 Crosslinking obtained by polycondensing terephthalic acid, trimellitic acid and polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane in a molar ratio of 2: 3: 6 35 parts by weight of a polyester resin (Tg 55 ° C.) and a styrene-acrylic acid n-butyl ester copolymer (having a peak at a molecular weight of 13,000 and 220,000 in GPC and a Tg of 60 ° C.)
5 parts by weight of a binder resin was used to prepare a toner in the same manner as in Comparative Example 1, and evaluated. Table 8 shows the results.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Nobuhiro Nakayama 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Fumihiro Sasaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Harumi Kakikawa 1-3-6 Nakamagome, Ota-ku, Tokyo, Japan Inside Ricoh Co., Ltd. (56) References JP-A-60-1223849 (JP, A) JP-A-57- 37353 (JP, A) JP-A-60-123850 (JP, A) JP-A-60-104956 (JP, A) JP-A-61-6656 (JP, A) JP-A-58-14149 (JP, A)

Claims (2)

(57) [Claims] 1. A toner for developing an electrostatic latent image containing at least a binder resin and a colorant, wherein the binder resin has a weight average molecular weight of 8,000 to 16000 and a glass transition temperature of 50 to 65.
An electrostatic latent image characterized by using a polyester resin having a styrene-methyl acrylate copolymer having a weight average molecular weight of 200,000 to 500,000, a gel content of 15 to 50%, and a glass transition temperature of 55 to 70 ° C. Development toner. 2. A polyester resin as a binder resin.
2. The toner for developing an electrostatic latent image according to claim 1, wherein the toner is contained in an amount of 20 to 45% by weight.