JPH036571A - Electrophotographic developer - Google Patents

Abstract

PURPOSE:To obtain a stable electrostatic charge characteristic by incorporating a modified polyester resin formed by modifying a polyester resin having a terminal OH group by using guanamine and one kind of guanamine deriv. into the developer. CONSTITUTION:The modified polyester resin formed by modifying the polyester resin having the terminal OH group by using the guanamine and one kind of guanamine deriv. is incorporated into the developer. The positive chargeable developer for electrophotography which has large electrostatic charge performance, is adequately controllable in electrostatic charge quantity, is hardly affected by environment, is stable thermally and with time and is applicable to chromatic developers having bright chromatic colors as the developer is colorless is obtd. in this way.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an electrophotographic developer, specifically an electrophotographic developer applied to the development of electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. The present invention relates to an electrophotographic developer suitable as a positively chargeable developer.

(Prior art) Electrophotography methods include U.S. Pat.
Various methods are described in the 48th publication etc., but the outline is that an electrostatic latent image is formed on a photoreceptor by a predetermined means,
Next, the latent image is developed using so-called toner, and if necessary, the toner is transferred to paper or the like, and then fixed by heating, pressure, or the like.

The developing methods applied to these electrophotographic methods include:
For example, a dry developing method is widely used, and there are two types: a method using a one-component developer in which a toner is used alone, and a method using a two-component developer in which a toner and a carrier are used together.

- Component-based development methods include the powder cloud method, contact development method, jumping development method, MagneDry method, etc., and two-component development methods include:
There are magnetic brush methods, cascade methods, fur brush methods, etc.

Toners applied to these developing methods can generally be produced by mixing and dispersing the main resin component, dyes and pigments as coloring components, and other desired ingredients, and then finely pulverizing the mixture.

It is important that the above-mentioned toner has chargeability in order to exhibit development performance. Therefore, generally, a charge control agent is added to the toner in order to impart desired triboelectric charging properties. Examples of the charge control agent include nigrosine, azine dyes, basic dyes,
Various compounds such as quaternary ammonium salts and organic tin compounds are used.

[Problem to be solved by the invention]

However, many of the above charge control agents are derived from dyes and pigments, and therefore many of them generally lack stability and, moreover, have strong coloring properties. For this reason, conventional toners do not necessarily have a sufficient amount of charge, and are easily affected by environmental factors such as temperature and toner density, resulting in the inability to reproduce stable images over a long period of time. was there.

In addition, it is difficult to obtain clear images because so-called "background fogging" is likely to occur, and the so-called "filming phenomenon" is likely to occur during long-term use, making it impossible to maintain the initial development characteristics. There were also problems.

Furthermore, as many charge control agents have strong coloring properties as mentioned above, they are difficult to apply to chromatic developers, and their light transmittance is poor, so 0HP (
Another problem was that it could not be used effectively as a developer for image formation (over-head projects).

Therefore, an object of the present invention is to have a sufficient amount of charge, have stable charging characteristics over a long period of time without being affected by the environment such as temperature and humidity, and therefore produce images that are stable for a long time. The object of the present invention is to provide a developer that can be reproduced.

Another object of the present invention is to provide a developer which has high image clarity because there is no blurring of the background caused by toner adhering to the background area during development, and there is no scattering of + toner to the edge periphery. It is about providing.

Another object of the present invention is to provide a developer that can stably maintain its initial characteristics without causing a filming phenomenon even when the developer is used continuously for a long period of time.

Another object of the present invention is to provide a developer that can be used as a chromatic developer and can produce bright chromatic images with good reproducibility and excellent light transmittance. .

[Means to solve the problem]

As a result of various studies, the present inventors have found that at least one of guanamine and guanamine derivatives is used as the main resin component.
By using a specific modified polyester resin obtained by denaturation with seeds, it has great charging performance and allows for appropriate control of the amount of charge, is not easily affected by the environment, and is stable both thermally and temporally. Furthermore, it has been found that an electrophotographic developer 11 is applicable to a chromatic developer that exhibits a vivid chromatic color because it is colorless, and is particularly suitable as a positively charging electrophotographic developer. .

The present invention was made based on the above knowledge, and
The present invention provides an electrophotographic developer containing a modified polyester resin obtained by modifying a polyester resin having IIjJ using at least one of guanamine and guanamine derivatives.

The present invention will be explained in detail below.

The electrophotographic developer of the present invention contains a toner for developing a so-called electrostatic image, and the toner contains, in addition to the main resin component detailed below, a colorant and an offset as commonly used components. It is prepared by a conventional method by containing an inhibitor and other additives as appropriate, and if necessary, an appropriate amount of a charge control agent, and can also be used as a one-component developer using toner alone. Moreover, both can be suitably used as a two-component developer in which a carrier is used together.

Preferred examples of the modified polyester resin which is the main resin component in the present invention include, for example, a polyhydric alcohol having a valence of 2 or more, a polybasic acid having a valence of 2 or more and/or its acid anhydride and/or its lower alkyl ester. Preferred examples include those obtained by polycondensing to obtain a polyester resin having a terminal OH group, and then reacting the polyester resin with at least one modification raw material selected from guanamine and guanamine 3A'L form. I can do it.

The polyester resin having a terminal OH group as a raw material for the modified polyester resin has an acid value of 5 [K OH+ag
/ g) or less, preferably 3
(KOH+wg/g) or less, and the hydroxyl value is 5.
It is desirable that it is 0 (KOHImg/g) or less, preferably 30 (KOHsg/g) or less.

If the acid value exceeds 5 (KOII mg/g), the negative polarity of the resin will be strong, and the effect of positive polarity modification will be small.
When the hydroxyl value exceeds 50 (KOHsg/g), the ester reaction is not sufficient and unreacted raw materials remain. However, it goes without saying that the acid value and hydroxyl value in 1- are not limited to the above ranges.

As one of the raw materials for producing the above-mentioned polyester resin having terminal OHI, polyhydric alcohols having a valence of 2 or more include ethylene glycol, polyethylene glycol,
Propylene glycol, polypropylene glycol, butylene glycol, polybutylene glycol, neopentyl glycol, 1.5-bentanediol, 1.6-
Examples include hexane glycol, hydrogenated bisphenol A1 bisphenol A alkylene oxide adduct, glycerin, trimethylolethane, trimethylolpropane, trishydroxyethyl isocyanurate, pentaerythritol, etc., and one of these may be used. It is also possible to use two or more kinds together.

In addition, as the other raw material, a divalent or higher polybasic acid,
Adipic acid, sebacic acid, itaconic acid, fumaric acid, maleic acid, maleic anhydride, orthophthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, succinic anhydride, alkyl succinic acid, alkyl succinic anhydride, alkenyl succinic acid acid, alkenylsuccinic anhydride, trimellitic acid, trimellitic anhydride, trimedic acid, cyanuric acid, pyromellitic acid, pyromellitic anhydride, etc., and it is also possible to use one of these, or two.
More than one species can be used in combination, and these are preferably used in the form of acid anhydrides or lower alkyl esters, and these can also be used in combination.

The raw material for modification is at least one of guanamine and guanamine derivatives, and considering hygroscopicity, charging stability, etc., the guanamine derivative has the following structural formula, substituents X, ~X, is preferably a hydrocarbon group such as aryl, alkyl, alkenyl, or hydrogen, and also includes melan, melon, and the like. However, it is not limited to this.

In the above-mentioned modified polyester resin, it is a serious matter that the above-mentioned guanamine or the above-mentioned guanamine derivative is chemically bonded to the polyester resin. The above-mentioned guanamine or guanamine derivative is desirably used in an amount of 1 to 40 parts of O per 100 parts of the polyester resin, preferably 0.5 to 20 parts, particularly preferably 1 to 10 parts. ``Part'' are all heavy 1-base tables).

The above modified polyester resin has a Tg (glass transition temperature)
is 50 to 70°C, preferably 55 to 65°C.

If Tg exceeds 70°C, the fixing temperature of the obtained toner will be higher than practical, and if Tg is less than 50°C, the storage stability of the obtained toner will be poor.

Further, the Tg of the modified polyester resin is preferably 1 to 10°C lower than the Tg of the polyester resin having OHM terminals before modification, in order to weaken the hydrogen bonding force between polymer chains.

Further, the modified polyester has a softening point of 80 to 150°C, preferably 90 to 130°C, as measured by a descending flow tester.
It is °C. If the softening point exceeds 150°C, the fixing temperature of the resulting toner will be higher than the practical range, and if the softening point is less than 80°C, the mechanical stability and
Poor storage stability.

Further, the softening point of the modified polyester resin is desirably 1 to 20°C lower than the softening point of the polyester resin having terminal 0Ill before modification for the same reason as in the case of TH.

The modified polyester resin of the present invention is produced by producing a polyester resin having an OH group at the terminal by a known polycondensation reaction using the raw materials as described above, and then modifying the polyester resin. It is something that can be done. However, the method is not limited to this method.

The above-mentioned polyester resin having a terminal OH group can be produced by any method without particular limitation, but specific methods include, for example, using an esterification catalyst (dibutyltin oxide, tetrabutyl titanate, p-toluenesulfonic acid, etc.). The reaction of polyhydric alcohols with acids and/or acid anhydrides, or the reaction of lower alkyl esters such as dimethyl dicarboxylic acid with polyhydric alcohols in the presence of transesterification catalysts (lead compounds, tin compounds, etc.). Examples of the reaction include transesterification, and reaction types include normal pressure dehydration, reduced pressure, vacuum dehydration, solution polycondensation, and solid phase polycondensation.

In addition, although the above modification is not particularly limited, it is important that it be thermally modified in a molten state after polycondensation, and this modification cannot normally be achieved in the temperature range of melting and dispersion during toner formation. is the terminal OH of guanamines and polyester resin.
This is thought to be due to the fact that weak ionic bonds with the groups can only be reached at sufficiently high temperatures.

In addition, the modified polyester resin obtained as described above is not particularly limited, but has an acid value of 4 or less and a hydroxyl value of 45.
The following are preferred.

As mentioned above, the electrophotographic developer of the present invention contains as a component a toner prepared by adding additives such as dyes and pigments and anti-offset agents to the above-mentioned modified polyester resin, and prepared according to a conventional method. It is suitable as a one-component or two-component dry developer for charged images, and is particularly suitable as a positively charged developer.

The content of the above-mentioned modified polyester resin in the above-mentioned toner is desirably 50 to 98%, preferably 60% to 98%, in order to fully exhibit the ja performance as a toner.
~95%.

In addition, the dyes and pigments constituting the above toner include carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, and Handy Yellow G10-Damine 6G.
Conventionally known dyes and pigments such as lake, calco oil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dyes, monoazo dyes, and diazo dyes and pigments can be used alone or in combination.

Further, as the anti-offset agent added to the above-mentioned toner, for example, a suitable amount of polypropylene wax, polyethylene wax, etc. can be blended.

Further, in the present invention, the above-mentioned toner may further contain a magnetic material as required, and may be used as a magnetic toner. Furthermore, it is also possible to use an appropriate amount of a charge control agent if necessary.

If necessary, the toner may be coated with conventionally known resins, such as vinyl resins such as styrene resins, styrene (meth)acrylate copolymer resins, and styrene butadiene copolymer resins, epoxy resins, and polyester resins. Appropriate amounts of resins, silicone resins, urethane resins, butyral resins, xylene resins, etc. can also be blended.

Toner containing the modified polyester resin detailed above as a main resin component is less susceptible to environmental influences,
One-component systems and two-component systems for electrostatic images that are stable over time, have excellent charging properties and chromatic light transmittance, and also have various properties required as electrophotographic developers such as anti-offset properties. It is also useful as a toner for any component-based dry developer.

In addition, when a resin material such as an amino resin or a guanamine resin is added as a charge control agent, the resulting toner image has poor light transmittance, and, for example, chromatic color reproducibility in full color development is poor. A phenomenon was observed in which the light transmittance of chromatic colors in a light transmitting image fixed on an OHP film was poor.

The present invention will be explained in more detail below based on Examples. In addition, unless otherwise specified in the text, "parts" are based on weight.

[Example] Hereinafter, the electrophotographic developer of the present invention will be specifically described based on Examples.

First, an example of manufacturing a modified polyester resin used in Examples described below will be described.

Production Example 1 65 parts of polyoxyethylene (2,2)-2,2-bis(4-hydroxyphenyl)propane, 1 part of ethylene glycol, and 34 parts of dimethyl terephthalate were mixed with 0.5 part of dibutyltin dilaurate in a glass container. The mixture was placed in a four-tube flask, fitted with a flowing condenser and a nitrogen inlet tube, and the demethanol reaction was carried out in an oil bath at -160°C under a nitrogen stream at normal pressure and at 200CM pressure with stirring. A polyester resin having terminal ora1 was produced. The obtained resin had an acid value of 3.1 (
KOT (mg/g), hydroxyl value: 16.7 (
KOI (+*g/g), 78 points by DSC (differential scanning calorimeter): Softening temperature = 105°C by 59.0°C1 descending flow tester.

Next, 6 parts of Henjiguanami was added to the above resin,
The reaction was carried out at 230°C under reduced pressure for 4 hours.

The obtained resin (modified polyester) has an acid value of 2°9
(KOHI1g/g), hydroxyl value: 15.4 [K
78 points by OHmg/gLDsc: 5 B, 2°C
The softening temperature was 2103° C. as measured by a descending flow tester.

Production example 2 Polyoxypropylene (2,2) -2,2-bis(4
70 parts of -hydroxyphenyl)propane, 2 parts of pentaerythritol, and 28 parts of fumaric acid were frozen at 150°C at normal pressure for the first half and at 200°C for the latter half using the same equipment as in Production Example 1, along with 0.5 parts of tetrabutyl titanate. The reaction was carried out under pressure to produce a polyester resin having terminal OH groups. The obtained resin had an acid value of 1.8 (KOI1m
g/g), hydroxyl value: 35.9 [KOHmg/g)
, 78 points by DSC: 62.0°C The softening temperature was 125°C by a descending flow tester.

Next, add 3 parts of guanamine to the above resin, and
The reaction was carried out under reduced pressure at C for 4 hours. The obtained resin (modified polyester) has an acid value: 1, 9 (KOHl 1g/g)
, hydroxyl value: 30.8 (KOI (mg/g), DS
78 points determined by C: 6O, O°C Softening temperature determined by a descending flow tester: 118°C.

Example 1 Modified polyester resin 10 obtained according to Production Example 1 above
0 parts and c, r, pigment red-81 as dyes
The mixture was mixed with 5 parts of the mixture using a Henschel mixer (manufactured by Mitsui Miike ■), and then melt-kneaded at 130°C using a Banbury mixer. After cooling, the obtained kneaded product was coarsely pulverized with a hammer mill, then finely pulverized with a Gent mill, and then classified with an air classifier to obtain a toner consisting of colored particles of 5 to 20 μm. Next, 4 parts of the above toner are mixed with 100 parts of iron powder carrier having an average particle size of 40 to 80 μ,
A two-component developer was prepared.

The electrophotographic developer of Example 1 prepared as described above was subjected to the following tests and evaluations.

The friction zone ff1l of the toner in the above developer was measured at 20°C965% (at room temperature,
+18.3 when measured under environmental conditions (normal temperature)
It was pc/g. In addition, under the environmental condition of 35°C 985% (high temperature and humidity), it is +18.0μC/g,
+18 under environmental conditions of 15°Cl2O% (low temperature, dry and wet)
．． 8 μc/g, and in both cases, toners with almost no difference in band Ti amount (not affected by the environment) compared to those at room temperature were obtained.

Next, a negative electrostatic charge image is formed on an OPC (organic photoreceptor) by a conventional method, a magnetic brush development method using the above developer is applied to this to create a toner image, and a toner image is formed on plain paper and OHI by a conventional method. The image was transferred onto a film for use with ', and then fixed using a heating roll.

The resulting image exhibited a bright red color and was a good image with high resolution and no background fog or toner scattering around the image. Also, a bright red color was obtained in the light transmission image of the OHP film image for presentation.

In addition, the durability in continuous transfer image processing on paper has been increased to 20%.
When examined under each environment of 965% °C, 35°C, 85%, and 920% 15°C, the transferred image after 30,000 sheets was no inferior to the initial image, and the background fog and line drawings were noticeably lost. It was a plain image. Also, 30,000
During the durability test of the sheet, no filming phenomenon caused by toner adhesion to the surface of the photoreceptor was observed, and there was no problem in practical use.

The above evaluation results are shown in Tables 1 and 2 below, along with the results of Example 2, Comparative Example 1, and Comparative Example 2 shown below.

Note that the evaluation g* in the table is based on the following content.

- Background fog 〇 - Both images or no cover 8 - There is a little fog on the image × - There is a lot of fog on the image ・Scattering 〇 - There is no scattering on both images Δ... There is a little bit of scattering on the image × - - The image Example 2 where the image exhibits a bright red color Modified polyester resin 10 obtained in the above Production Example 2
An electrophotographic developer of Example 2 was prepared in the same manner as in Example 1, except that 0 parts by weight and 7 parts by weight of carbon black were used as the dye and pigment.

Regarding the electrophotographic developer of Example 2, images were created by performing development, transfer, and fixing in the same manner as in Example 1, and the same tests and evaluations were conducted.

From the results in Tables 1 and 2, almost the same satisfactory results as in Example 1 were obtained.

Comparative Example 1 In Production Example 1, 6 parts of benzoguanamine and 5.3 parts of C,1, Pigment Red-81 were added to Henschel by using 100 parts of the polyester resin having a terminal O1l group before being modified with benzoguanamine. A developer of Comparative Example 1 was prepared in the same manner as in Example 1 except that the mixture was mixed in a mixer and then melted and kneaded in a Banbury mixer.

Using the developer of Comparative Example 1, development, transfer, and fixing were performed in the same manner as in Example 1 to create an image.
A similar test evaluation was conducted.

From the results in Tables 1 and 2, the amount of triboelectric charge is ±7.1pc/
g, the image density is thin, and the line drawings are scattered - 1 Also, in the durability test, a filming phenomenon caused by toner adhesion to the photoreceptor began to appear around the time of too much, resulting in a decrease in density, background fogging, and scattering. It increased. Further, large changes in the amount of charge occurred over time and due to changes in the environment.

Comparative Example 2 In Production Example 2, using 100 parts of the polyester resin having the terminal 011i before modification with guanamine,
A developer of Comparative Example 2 was prepared in the same manner as in Example 1, except that 2 parts by weight of nigrosine dye (Nigorosine Base EX manufactured by Orient Kagaku Kogyo ■) and 7 parts of carbon black were blended.

Using the developer of Comparative Example 2, development, transfer, and fixing were performed in the same manner as in Example 1 to create an image.
A similar test evaluation was conducted.

From the results in Tables 1 and 2, there was a lot of background fog (and the image density was low. When images were created at 35°C and 85% conditions, the image density was low, and the background fog and skipping increased. , the transfer efficiency was also low.

Further, in a durability test, a filming phenomenon caused by toner adhesion to the photoreceptor began to appear after around 5,000 sheets, and there was a remarkable tendency for density reduction, background fogging, and scattering.

Above, the electrophotographic developer of the present invention has been specifically explained with reference to examples of a one-component type electrophotographic developer, but it is not limited thereto, and it is possible to use a two-component type electrophotographic developer. Not even.

[Effects of the Invention] The electrophotographic developer of the present invention has a large amount of charge, is not affected by environments such as temperature and humidity, has stable charging characteristics over a long period of time, and has high image clarity. However, since no filming phenomenon occurs even during continuous use, excellent images can be stably obtained over a long period of time.Moreover, when used as a chromatic color developer,
A vivid chromatic image with excellent light transmittance can be obtained with good reproducibility.

Claims (5)

[Claims] (1) An electrophotographic developer characterized by containing a modified polyester resin obtained by modifying a polyester resin having a terminal OH group using at least one of guanamine and guanamine derivatives. (2) The above polyester resin having a terminal OH group has an acid value of 5 [KOHmg/g] or less and a hydroxyl value of 50 [KOHm
g/g] or less. (3) The electrophotographic developer according to claim 1, wherein the modified polyester has a Tg of 50 to 70°C. (4) Claim (1) wherein the softening point of the modified polyester resin measured by a descending flow tester is 80 to 1500°C.
) The electrophotographic developer described in ). (5) The electrophotographic developer according to claim 1, wherein the electrophotographic developer containing the modified polyester resin is a positively charged developer.