JP2007316585A - Resin composition for toner and toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for toner which enables to obtain a toner excellent in low-temperature fixability, high-temperature offset resistance and image quality, and to provide a toner. <P>SOLUTION: The resin composition for toners is obtained by reacting a branched polyester having a hydroxyl number of 5-100 with an isocyanate compound having two or more isocyanate groups in one molecule. The resin composition contains an unreacted portion of the branched polyester having a molecular weight not over the peak molecular weight of the branched polyester before the reaction, and when a molecular weight distribution of a tetrahydrofuran-soluble component is measured by gel permeation chromatography, a peak area in a range not over the peak molecular weight of the branched polyester before the reaction is 20-45% of the total peak area. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a toner resin composition and a toner capable of obtaining a toner excellent in low-temperature fixability, high-temperature offset resistance and image quality.

A dry development method is frequently used as a method for developing an electrostatic image in electrophotography or the like. In the dry development system, the toner is usually charged by friction with iron powder, glass beads, etc., called a carrier, which adheres to the electrostatic latent image on the photoreceptor by electrical attraction, and then transferred onto the paper, It is fixed by a heating roller or the like and becomes a permanent visible image.

As a fixing method, a heating roller method is generally used in which a toner image of a fixing sheet is passed through a surface of a heat fixing roller formed with a material having releasability with respect to a toner while being in pressure contact. ing.

When this heat fixing roller method is used, a toner that can be fixed at a lower temperature is required in order to improve economy such as power consumption and increase the copying speed.
However, when trying to improve the low-temperature fixability described above, an offset phenomenon in which a part of the toner adheres to the surface of the heat-fixing roller and retransfers to the paper is likely to occur, or the resins are subjected to various environments. There is a problem that a blocking phenomenon in which toner aggregates easily occurs due to heat.

To deal with such a problem, Patent Document 1 discloses that as a binder resin for toner, a unit derived from terephthalic acid and a linear alkylene glycol having 2 to 6 carbon atoms is used in an amount of 50 mol with respect to all the monomer units used. A method using a crystalline polyester containing at least% is disclosed.
However, in such a method, since only the crystalline polyester resin is used, it is difficult to maintain the high-temperature offset resistance without impairing the low-temperature fixability because the temperature range capable of fixing is narrow.

Patent Document 2 discloses a method of using a polyester obtained by copolymerizing a trivalent or higher polyvalent monomer, an aromatic dicarboxylic acid component and an aliphatic dialcohol. In the polyester thus obtained, a crosslinked polymer having a chemically crosslinked structure is formed in the polymer, so that high temperature offset resistance can be maintained.
However, in such a method, since the degree of cross-linking density of the polyester cannot be controlled, a low molecular weight polymer to a high molecular weight cross-linked polymer exist, and the molecular weight distribution of the obtained non-crystalline polyester becomes wide. In particular, the low-temperature fixability was not sufficient.

Furthermore, Patent Document 3 discloses a method of using a crosslinked polyester obtained by reacting a dibasic carboxylic acid, a diol, and a triol, and reacting a polyester having a hydroxyl value of 6 to 100 with a predetermined amount of isocyanate. Is disclosed. However, in such a method, the crosslinking between the polyester and the isocyanate is insufficient, and the high-temperature offset resistance of the resulting toner is impaired, so it is difficult to achieve both high-temperature offset resistance and low-temperature fixability. It was.
Accordingly, there has been a demand for a binder resin for toner that can obtain a toner having an appropriate crosslinking density and having high-temperature offset resistance and low-temperature fixability.
Japanese Patent No. 2988703 Japanese Patent No. 2704282 Japanese Patent No. 29986820

An object of the present invention is to provide a resin composition for a toner and a toner capable of obtaining a toner excellent in low-temperature fixability, high-temperature offset resistance and image quality.

The present invention relates to a resin composition for a toner obtained by reacting a branched polyester having a hydroxyl value of 5 to 100 with an isocyanate compound having two or more isocyanate groups in one molecule, and the branched before reaction. The unreacted branched polyester having a molecular weight equal to or lower than the peak molecular weight of the linear polyester, and when the molecular weight distribution of tetrahydrofuran solubles is measured using gel permeation chromatography, the branched polyester before the reaction The toner resin composition has a peak area in the range of not more than the peak molecular weight of 20 to 45% with respect to the total peak area.
The present invention is described in detail below.

As a result of intensive studies, the present inventors have reacted a branched polyester with an isocyanate compound to form a crosslinked structure having an appropriate crosslinking density, and can exhibit good high temperature offset resistance. It has been found that by leaving unreacted branched polyester having a predetermined molecular weight in an appropriate ratio, good low-temperature fixability can be expressed. In addition, since the cross-linked structure and the unreacted branched polyester having a predetermined molecular weight are excellent in compatibility, the powder is uniformly dispersed. The inventors have found that a resin composition for a toner that can be dispersed and can obtain a toner having excellent image quality can be produced, and the present invention has been completed.

The resin composition for toner of the present invention is obtained by reacting a branched polyester having a hydroxyl value of 5 to 100 with an isocyanate compound having two or more isocyanate groups in one molecule.
A crosslinked structure is formed by reacting the branched polyester with an isocyanate compound. The resin composition for a toner of the present invention has a cross-linked structure composed of the branched polyester and an isocyanate compound, so that the high-temperature offset resistance of the obtained toner can be maintained.

The lower limit of the hydroxyl value of the branched polyester is 5, and the upper limit is 100. If it is less than 5, the crosslinking reaction point of the branched polyester is reduced, so that the resulting crosslinked polyester has a low crosslinking density, resulting in insufficient high-temperature offset resistance. Crosslinking reaction points increase, crosslinking density increases, and high temperature offset resistance improves, but low temperature fixability decreases. The preferred lower limit is 10, and the preferred upper limit is 90. A more preferred lower limit is 20, and a more preferred upper limit is 80.

The branched polyester is preferably obtained by reacting a dicarboxylic acid, a diol and a trivalent or higher polyvalent carboxylic acid or a trivalent or higher polyhydric alcohol.
In the present specification, the branched polyester refers to a polyester having a branched structure in the polyester skeleton.

Examples of the method of reacting the dicarboxylic acid, diol and trivalent or higher polyvalent carboxylic acid or trivalent or higher polyhydric alcohol include, for example, batch-feeding the dicarboxylic acid, diol and tricarboxylic acid into a reaction kettle, It can be obtained by a method of reaction and condensation reaction. In this method, if the amount of tricarboxylic acid added is increased, the reaction may proceed too quickly and the molecular weight may increase. In such a case, a transesterification reaction between a dicarboxylic acid and a diol is first performed, and when the transesterification reaction is almost completed, a tricarboxylic acid is added and reacted to obtain a branched polyester having desirable physical properties. it can.

Examples of the dicarboxylic acid include o-phthalic acid, terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octyl succinic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, maleic acid, and itacone. Examples include acids, decamethylene carboxylic acids, anhydrides and lower alkyl esters thereof. Among these, terephthalic acid, naphthalenedicarboxylic acid, and anhydrides and lower alkyl esters thereof are preferably used for imparting crystallinity.

Examples of the diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, triethylene glycol, and tetraethylene. Glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 1,2-hexanediol, 2, Aliphatic diols such as 5-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol; 4-hydroxycyclohexyl) propane, 2,2-bis (4-hydroxycyclo) Hexyl) alkylene oxide adducts of propane, 1,4-cyclohexane diol, alicyclic diols such as 1,4-cyclohexanedimethanol. Of these, aliphatic diols are preferred.

As the trivalent or higher polyvalent carboxylic acid, for example, tricarboxylic acid can be used. In addition to the above tricarboxylic acid, pyromellitic acid, 1,2,7,8-octanetetracarboxylic acid and acid anhydrides thereof may be used. In addition, these may be used independently and may use 2 or more types together.
Examples of the tricarboxylic acid include trimellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid. Examples include acids and acid anhydrides thereof.

Examples of the trihydric or higher polyhydric alcohol include sorbitol, 1,2,3,6-hexanetetralol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2, 4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-triol Examples thereof include hydroxymethylbenzene. In addition, these may be used independently and may use 2 or more types together.

The preferable lower limit of the amount of the trivalent or higher polyvalent carboxylic acid or the trivalent or higher polyhydric alcohol is 0.5 mol% with respect to the amount of the dicarboxylic acid added, and the preferable upper limit is 20 mol%. If the amount is less than 0.5 mol%, the branched portion of the resulting branched polyester is reduced, and the reactivity with the isocyanate compound may be reduced. Moreover, even if it makes it react with an isocyanate compound, the crosslinked polyester which has sufficient crosslinking density cannot be obtained, and high temperature offset resistance may become inadequate. If it exceeds 20 mol%, the crosslink density is increased and the high temperature offset resistance is improved, but the low temperature fixability may be lowered.

The above-mentioned branched polyester has a preferable lower limit of the number average molecular weight of 2000 and a preferable upper limit of 7000. If it is less than 2000, the offset resistance and durability of the obtained toner may be insufficient, and if it exceeds 7000, the obtained toner may be inferior in low-temperature fixability. A more preferred upper limit is 5000.

The above-mentioned branched polyester has a preferable lower limit of the average degree of branching of 2.1 and a preferable upper limit of 7.0. If it is less than 2.1, the crosslinking reaction point of the branched polyester is reduced, so that the crosslinking density of the obtained crosslinked polyester is lowered, and the high temperature offset resistance may be lowered, and exceeds 7.0. In addition, the crosslinking reaction point of the branched polyester is increased, the crosslinking density is increased, and the high temperature offset resistance is improved, but the low temperature fixing property is sometimes lowered.
In this specification, the average degree of branching is obtained by dividing the number of hydroxyl groups per 1 g of branched polyester (NOH) by the number of molecules per 1 g of branched polyester (N) as shown in the following formula (1). Say. In addition, NOH is represented by NOH = 1 / Mn using the number average molecular weight (Mn), and N is N = OHV × 10 ⁻³ / 56. Using the hydroxyl value (OHV) of the branched polyester. It is represented by 1. Therefore, the average degree of branching can also be expressed using Mn and OHV.
Here, when the average degree of branching is 2.0, it indicates that all the polyesters are linear polyesters, and that the proportion of the branched polyester is larger as the average degree of branching is larger than 2.0. Show.

The minimum with a preferable glass transition temperature of the said branched polyester is 30 degreeC, and a preferable upper limit is 80 degreeC. If it is less than 30 ° C., high-temperature offset resistance and blocking resistance cannot be sufficiently obtained, and if it exceeds 80 ° C., low-temperature fixability is inferior. A more preferred lower limit is 50 ° C., and a more preferred upper limit is 65 ° C.

Regarding the glass transition temperature of the branched polyester, aromatic dicarboxylic acids such as terephthalic acid work to improve the glass transition temperature, and long-chain aliphatic dicarboxylic acids such as sebacic acid and adipic acid lower the glass transition temperature. Therefore, the desired glass transition temperature can be achieved by appropriately combining these dicarboxylic acids. However, even if an objective glass transition temperature can be achieved by appropriately combining an aromatic dicarboxylic acid and a long-chain aliphatic dicarboxylic acid, the softening temperature tends to be too high.
Therefore, the branched polyester includes a polyvalent carboxylic acid and a polyhydric alcohol containing at least either a divalent bent monomer capable of introducing a bent molecular structure into the molecular chain or a divalent monomer having a branched chain. It is preferable to polymerize the monomer mixture.
A polymer obtained by polymerizing a monomer mixture containing a divalent bending monomer or a divalent monomer having a branched chain can more easily achieve a target glass transition temperature and a low softening temperature.

Examples of the divalent bending monomer include aromatic dicarboxylic acids in which the ortho position or the meta position is substituted with a carboxyl group, aromatic diols in which the ortho position or the meta position is substituted with a hydroxyl group, and many having a carboxyl group in an asymmetric position. It is not limited to dicarboxylic acids and diols as long as it is a monomer that can introduce a molecular structure bent into the molecular chain of a polymer such as a ring aromatic dicarboxylic acid or a polycyclic aromatic diol having a hydroxyl group at an asymmetric position. Products, lower esters, monohydroxymonocarboxylic acids, etc., for example, dicarboxylic acids such as phthalic anhydride, o-phthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, etc. And their anhydrides and lower esters; salicylic acid, 3-hydroxy-2-naphthalene Monohydroxy monocarboxylic acids such as carbon acid; catechol include diols such as 1,4-cyclohexanedimethanol.

A divalent monomer having a branched chain effectively suppresses crystallization of the polymer due to steric hindrance of the branched chain. Examples of the monomer having a branched chain that can effectively suppress crystallization include an aliphatic diol having a branched alkyl chain and an alicyclic diol having a branched alkyl chain. The alicyclic diol is preferably an alicyclic diol in which a plurality of alicyclic diols are linked by a branched alkylene chain.
The divalent monomer having a branched chain is not particularly limited. For example, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane- 1,3-diol), 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3 -Aliphatic diols such as hexanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol; 2,2-bis (4-hydroxycyclohexyl) propane, And alicyclic diols such as an alkylene oxide adduct of 2,2-bis (4-hydroxycyclohexyl) propane.

The isocyanate compound has two or more isocyanate groups in one molecule. When the number of the isocyanate groups is less than 2 in one molecule, the formation of a crosslinked polyester is insufficient, and the high temperature offset resistance is lowered.
Preferably, it is 3 or more per molecule. By using three or more molecules per molecule, the reactivity between the branched polyester and the isocyanate compound is improved, and the crosslinking density is moderate. Therefore, a resin composition for toner that provides a toner having excellent high-temperature offset resistance can be obtained. Can be manufactured.
Polymeric MDI is preferable as the isocyanate compound having three or more isocyanate groups in one molecule.

In the above isocyanate compound, the preferable lower limit of the isocyanate group content is 0.3 mol and the preferable upper limit is 3 mol with respect to 1 mol of the branched polyester. If the amount is less than 0.3 mol, the formation of the crosslinked polyester becomes insufficient, and the high temperature offset resistance may decrease. If it exceeds 3 moles, the excess isocyanate compound not involved in crosslinking increases, and the physical properties of the isocyanate compound itself are close, so that physical properties such as low-temperature fixability may be deteriorated.

The isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups in one molecule. For example, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, Trimethylhexamethylene diisocyanate, diphenylmethane-4,4′-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, Lysine diisocyanate, triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, tetramethylxylene diisocyanate, 1,6,6 0 down de country isocyanate, and the like.

The resin composition for toner of the present invention contains an unreacted branched polyester (hereinafter also referred to as an unreacted branched polyester) having a molecular weight equal to or lower than the peak molecular weight of the branched polyester before the reaction.
In the present specification, the unreacted branched polyester having a molecular weight equal to or lower than the peak molecular weight of the branched polyester before the reaction refers to the branched polyester remaining after the reaction between the branched polyester and the isocyanate compound. Among them, it means a branched polyester having a molecular weight equal to or lower than the peak molecular weight obtained by measuring the tetrahydrofuran-soluble content of the branched polyester before the reaction by gel permeation chromatography.

The resin composition for a toner of the present invention contains an unreacted product of the branched polyester, whereby the obtained toner can have an appropriate low-temperature fixability.
In addition, the cross-linked structure composed of the branched polyester and the isocyanate compound and the unreacted product of the branched polyester have very good compatibility. As a result, the resin composition for toner according to the present invention has a structure in which the unreacted material of the branched polyester is uniformly mixed with a crosslinked structure having an appropriate crosslinking density. It is possible to produce a toner with an excellent balance of properties, and it is possible to produce a toner with excellent image quality due to good dispersibility of compounding agents such as a release agent, a colorant, a charge control agent, and magnetic powder. Become.

The method for measuring the content of the unreacted branched polyester in the toner resin composition of the present invention is not particularly limited, but the tetrahydrofuran-soluble component (hereinafter referred to as THF-soluble component) of the toner resin composition of the present invention is not particularly limited. Area) with respect to the total peak area of the peak area in the range below the peak molecular weight of the branched polyester before the reaction when the molecular weight distribution is measured using gel permeation chromatography (hereinafter also referred to as GPC). By measuring the ratio, it can be used as a standard for the content of the unreacted material of the branched polyester.

The following methods can be used as means for measuring the area ratio of the peak area within the range of the peak molecular weight of the branched polyester before the reaction to the total peak area.
1A and 1B are molecular weight distribution curves obtained when the THF-soluble content of the resin composition for toner of the present invention is measured by GPC.
First, from the molecular weight distribution curve (FIG. 1a) obtained when the THF soluble content of the resin composition for toner of the present invention is measured by GPC, the area of the A region, which is the total peak area, is obtained. Next, from the same molecular weight distribution curve (FIG. 1b), the area of the B region which is a range below the peak molecular weight (x in FIG. 1b) obtained by measuring the molecular weight distribution curve of the branched polyester before the reaction in advance. Ask. And the area ratio with respect to all the peak areas of the peak area of the range below the peak molecular weight of the branched polyester before the said reaction can be calculated | required by calculating the ratio of the area of B area | region with respect to A area | region.

When the molecular weight distribution of the THF soluble content of the resin composition for toner of the present invention is measured using GPC, the peak area in the range below the peak molecular weight of the branched polyester before the reaction is lower than the total peak area. 20%, upper limit is 45%. If it is less than 20%, the high-temperature offset resistance is improved, but the low-temperature fixability may be lowered. If it exceeds 45%, the high-temperature offset resistance may be insufficient.

The GPC measuring device is not particularly limited, and examples thereof include HTR-C (manufactured by Nihon Millipore Limited), GPC-101 (manufactured by Showa Denko KK), and the like.
The column used for the GPC is not particularly limited, and examples thereof include KF-800 series (made by Showa Denko KK) and TSK-GEL HHR series (made by Tosoh Corporation).

The method for producing the resin composition for toner of the present invention is not particularly limited. For example, a branched polyester having a hydroxyl value of 5 to 100 and an isocyanate compound having two or more isocyanate groups in one molecule are used. It is preferable to have a step of kneading with an extrusion kneader.

In the method for producing a resin composition for a toner of the present invention, a low molecular weight linear polyester may be further mixed in the kneading step by the extrusion kneader. By mixing the low molecular weight linear polyester, the low-temperature fixability of the obtained toner can be improved. In addition, in the middle of the process of kneading the branched polyester and the isocyanate compound as described above, the branched polyester and the isocyanate compound mainly undergo a crosslinking reaction even if a low molecular weight linear polyester is added. A crosslinked polyester is formed, and the low molecular weight linear polyester hardly reacts with the isocyanate compound. Therefore, since the resulting resin composition for toner has a structure in which a low molecular weight linear polyester is uniformly mixed with a crosslinked polyester having an appropriate crosslinking density, a toner having an excellent balance between low-temperature fixability and high-temperature offset resistance can be obtained. It can be set as the resin composition for toners which can be produced.
In addition, in this specification, linear polyester means polyester in which an ester structure exists in linear form. However, the linear polyester may be one in which the terminal portion is acid-modified with carboxylic acid or the like.

It does not specifically limit as said low molecular weight linear polyester, For example, what is obtained by polycondensing dicarboxylic acid and diol can be used.
In addition, as said dicarboxylic acid and diol, the thing similar to the branched polyester mentioned above can be used.

The preferable lower limit of the number average molecular weight of the low molecular weight linear polyester is 2000, and the preferable upper limit is 5000. If it is less than 2000, the resulting toner may have insufficient blocking resistance, and if it exceeds 5000, the low-temperature fixability may be inferior.

The preferable lower limit of the glass transition temperature of the low molecular weight linear polyester is 30 ° C., and the preferable upper limit is 80 ° C. When the temperature is lower than 30 ° C., the blocking resistance may not be sufficiently obtained. When the temperature exceeds 80 ° C., the effect of improving the low-temperature fixability by the addition of the linear polyester may not be sufficiently exhibited.

The hydroxyl value of the low molecular weight linear polyester is not particularly limited. Generally, the greater the hydroxyl value, the higher the reactivity with the isocyanate compound. However, in the resin composition for toner of the present invention, the reactivity with the branched polyester is high, and the low-molecular-weight linear polyester is almost composed of the isocyanate compound. Since there is no reaction, the hydroxyl value is not particularly limited.

A preferable upper limit of the content of the low molecular weight linear polyester is 90% by weight with respect to the whole resin composition for toner. If it exceeds 90% by weight, the low-temperature fixability may be deteriorated, or a kneading failure with the formed crosslinked polyester may occur, resulting in a global offset without a toner fixing region.

When the low molecular weight linear polyester is further mixed when the toner resin composition of the present invention is produced, the mixing weight ratio of the branched polyester and the low molecular weight linear polyester is 20:80 to 80:20. It is preferable that When the ratio of the branched polyester is less than 20% by weight, the reactivity with the isocyanate compound may be lowered. When the ratio is more than 80% by weight, the low molecular weight component becomes too small, and the low-temperature fixability of the obtained toner is low. May decrease. A more preferable mixing weight ratio is 30:70 to 70:30.

In the step of kneading the branched polyester and the isocyanate compound with an extrusion kneader when producing the resin composition for a toner of the present invention, another polyester may be used as long as the properties of the resulting resin composition for the toner are not impaired. May be added.

As said another polyester, the linear polyester etc. whose said number average molecular weight is 2000-10,000 are mentioned, for example. By introducing a linear polyester having a number average molecular weight of 2000 to 10,000 (hereinafter also simply referred to as linear polyester), the crosslinking density of the crosslinked polyester obtained after crosslinking can be made moderate. Polyester and linear polyester can be mixed uniformly.

As said linear polyester, what is obtained by condensation-polymerizing dicarboxylic acid and diol can be used, for example.
In addition, as said dicarboxylic acid and diol, the thing similar to the branched polyester mentioned above can be used.

The preferable lower limit of the number average molecular weight of the linear polyester is 2000, and the preferable upper limit is 10,000. If it is less than 2000, the toner has insufficient blocking resistance, and if it exceeds 10,000, the low-temperature fixability may deteriorate. A more preferred lower limit is 2500, and a more preferred upper limit is 6000.

When the other polyester is added when the toner resin composition of the present invention is produced, a preferable upper limit of the addition amount is 30% by weight. If it exceeds 30% by weight, the low-temperature fixability and high-temperature offset resistance of the resulting toner may be impaired. A more preferred lower limit is 20% by weight.

When the toner resin composition of the present invention is produced, the branched polyester and the isocyanate compound may be reacted in the presence of moisture. By using such a method, a crosslinked polyester having many urea bonds in the molecule can be produced. As a result, the obtained crosslinked polyester has excellent heat resistance and is not easily thermally decomposed during kneading, so that it becomes a resin having stable physical properties.
The method of reacting in the presence of moisture is not particularly limited, and examples thereof include a method using a branched polyester containing water as a raw material and a method of adding water simultaneously with the raw material.

When using the polyester containing water as a raw material, the minimum with a preferable water content is 0.01 weight% and a preferable upper limit is 1.0 weight%. If it is less than 0.01% by weight, a sufficient urea bond cannot be formed, and if it exceeds 1.0% by weight, the polyester may undergo hydrolysis and the molecular weight may be greatly reduced.

When the toner resin composition of the present invention is produced, a polyhydric alcohol may be further added in the step of kneading the branched polyester and the isocyanate compound with an extrusion kneader. Thereby, the crosslinked polyester which has a desired crosslinking density can be obtained.

The polyhydric alcohol is not particularly limited, and for example, sorbitol, 1,2,3,6-hexanetetralol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2 , 4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5- And trihydroxymethylbenzene. In addition, these may be used independently and may use 2 or more types together.

The minimum with the preferable addition amount of the said polyhydric alcohol is 0.01 weight%, and a preferable upper limit is 3.0 weight%. When the content is less than 0.01% by weight, the effect of adding the polyhydric alcohol is not sufficiently exhibited. When the content exceeds 3.0% by weight, the crosslinking density is excessively increased and the dispersibility of the low molecular weight linear polyester is lowered. Sometimes.

The extrusion kneader used for producing the toner resin composition of the present invention is not particularly limited, but the crosslinking reaction between the branched polyester and the isocyanate compound can be sufficiently advanced, and continuous production is possible. For this reason, a monoaxial or biaxial extrusion kneader is preferable, and a biaxial extrusion kneader is more preferable.

In the case of using an extruder with a built-in screw, the preferable lower limit of the ratio (L / D) of the length (L) to the screw diameter (D) is 20, and the preferable upper limit is 100. If it is less than 20, the length of the screw is short, and kneading may be insufficient. If it exceeds 100, the heating time becomes long, and the generated crosslinked polyester is thermally decomposed or deteriorated. The offset property may not be improved. Note that this is not the case when a special extrusion kneader is used.

Moreover, the preferable minimum of the residence time in the said extrusion kneader is 3 minutes, and a preferable upper limit is 30 minutes. If it is less than 3 minutes, the crosslinking reaction may be insufficient. If it exceeds 30 minutes, the generated crosslinked polyester may be thermally decomposed or thermally deteriorated, so that the high temperature offset resistance may not be improved. A more preferred lower limit is 5 minutes, and a more preferred upper limit is 20 minutes.

When kneading using the extrusion kneader, the kneading temperature is such that the crosslinking reaction between the branched polyester and the isocyanate compound proceeds sufficiently to obtain a crosslinked polyester, and the crosslinked polyester and low molecular weight line are obtained. The temperature is not particularly limited as long as the temperature can sufficiently melt and knead the shaped polyester, and the preferable lower limit is 100 ° C and the preferable upper limit is 230 ° C. When the temperature is less than 100 ° C., the crosslinking reaction is difficult to proceed and the formation of the crosslinked polyester may be insufficient. When the temperature exceeds 230 ° C., the generated crosslinked polyester is thermally decomposed or thermally deteriorated. The offset property may not be improved.

In the resin composition for toner of the present invention, a preferable lower limit of the flow softening point is 100 ° C., and a preferable upper limit is 160 ° C. When the temperature is lower than 100 ° C., the high temperature offset resistance becomes insufficient, and when the temperature exceeds 160 ° C., the low temperature fixing property may be deteriorated. A more preferred upper limit is 150 ° C., and a more preferred upper limit is 145 ° C.
In this specification, the flow softening point refers to, for example, a high-flow type flow tester (for example, “CFT-500 type” manufactured by Shimadzu Corporation), load 20 kg / cm ² , orifice 1 mmφ × 1 mm, spare It passes through a JIS standard sieve with an opening of 1.19 mm under conditions of a temperature of 60 ° C., a preparatory time of 5 minutes, a chart speed of 20 mm / min, a plunger of 1.0 cm ² , and a temperature increase rate of 6 ± 0.5 ° C./min. When the measurement sample of 1.0 g was melted and flowed out and the relationship between the plunger drop amount and the temperature was determined, the plunger drop amount at the start of the resin flow and the plunger drop amount at the stop of the resin flow It means the temperature Tf when giving an intermediate plunger lowering amount h / 2.
FIG. 2 is a diagram showing the relationship between the plunger lowering amount and the time (temperature) when the flow softening point Tf is obtained by the constant speed temperature raising method.

When the toner resin composition of the present invention is subjected to a shear strain of 450% under the condition of 170 ° C., the relaxation elastic modulus G _{170 ° C.} (0.1 ) Is preferably 100 Pa, and a preferable upper limit is 1500 Pa.
As a result of intensive studies, the present inventors have found that the offset phenomenon in the toner occurs when the cohesive force of the melted toner is smaller than the adhesive force between the toner and the heat-fixing roller. It was found that there is a relationship between the cohesive strength of the resin composition for toner and the relaxation elastic modulus of the resin composition for toner under large deformation. As a result of further intensive studies, the present inventors have found that the use of a toner resin composition having a certain relaxation modulus can improve the low-temperature fixability while maintaining the high-temperature offset resistance of the toner.
The relaxation elastic modulus is obtained by, for example, using a toner sample composition of the present invention melted and then molded into a disk shape of a predetermined size as a test sample, and using a relaxation elastic modulus measuring apparatus (for example, a tea -It can measure using instrument company make, ARES, etc.).

The acid value of the resin composition for toner of the present invention is not particularly limited, but a preferable lower limit is 1 and a preferable upper limit is 30. Such an acid value is attributed to a functional group at the end of the crosslinked polyester or the linear polyester, specifically, for example, a carboxyl group. When the acid value is in this range, the toner obtained is excellent in low-temperature fixability, and the affinity with paper is also improved.

Using the resin composition for toner of the present invention as a binder resin, if necessary, for a toner comprising a release agent, a colorant, a charge control agent, a magnetic material, a rubbery polymer, and a styrene-acrylate copolymer A toner can be produced by mixing with a resin, a carrier, a cleaning property improving agent and the like. Such a toner is also one aspect of the present invention.
The toner of the present invention does not need to contain a release agent because it is excellent in both low-temperature fixability and high-temperature offset resistance by using the resin composition for toner of the present invention.

The release agent is not particularly limited, and examples thereof include olefin waxes such as polypropylene wax, polyethylene wax, microcrystalline wax, and oxidized polyethylene wax, and paraffin waxes; fats such as carnauba wax, sazol wax, and montanic ester wax. Desaturated carnauba wax; Saturated aliphatic acid wax such as baltimic acid, stearic acid, and montanic acid; Unsaturated aliphatic acid wax such as pracidic acid, eleostearic acid, and valinalic acid; Stearyl alcohol; Saturated alcohols and aliphatic alcohols such as aralkyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, and melyl alcohol; polyhydric alcohols such as sorbitol Saturated fatty acid amide waxes such as linoleic acid amide, oleic acid amide, lauric acid amide; saturated fatty acid bisamides such as methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, hexamethylene bisstearic acid amide Wax; Unsaturated acid amide wax such as ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; m-xylene bisstearin Aromatic bisamide waxes such as acid amides and N, N′-distearylisophthalic acid amides; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate; vinyl monomers such as styrene and acrylic acid Graft-modified wax obtained by graft polymerization of mer to polyolefin; Partial ester wax obtained by reacting fatty acid such as behenic monoglyceride with polyhydric alcohol; Methyl ester wax having hydroxyl group obtained by hydrogenating vegetable oil; Examples thereof include ethylene-vinyl acetate copolymer waxes having a high component content; long-chain alkyl acrylate waxes such as saturated stearyl acrylate waxes such as acrylic acid; aromatic acrylate waxes such as benzyl acrylate waxes. Of these, long-chain alkyl acrylate waxes and aromatic acrylate waxes are preferred because they are highly compatible with the toner resin composition and provide a highly transparent toner. These release agents may be used alone or in combination of two or more, but it is particularly preferable to use in combination of two or more release agents having a melting point of 30 ° C. or more.
The size of the release agent in the toner is not particularly limited, but the major axis is preferably 2 μm or less.

The colorant is not particularly limited. For example, carbon black such as furnace black, lamp black, thermal black, acetylene black, channel black, aniline black, phthalocyanine blue, quinoline yellow lamp black, rhodamine-B, azo pigment, Examples include perylene pigments, perinone pigments, anthraquinone pigments, dioxazine pigments, isoindoline pigments, isoindolinone pigments, selenium pigments, indico pigments, quinophthalone, diketopyrrolopyrrole, and quinacridone.
The preferred lower limit of the blending amount of these colorants is usually 1 part by weight with respect to 100 parts by weight of the toner resin composition, and the preferred upper limit is 10 parts by weight.

There are two types of charge control agents, positive charge and negative charge. Examples of the charge control agent for positive charge include nigrosine dyes, ammonium salts, pyridinium salts, and azines. Examples of the charge control agent for negative charge include chromium complexes and iron complexes. Among these, an acid-modified charge control agent is suitable, and when it is salicylic acid-modified, it crosslinks with the toner resin composition and develops rubber elasticity. Metal complexes of alkyl-substituted salicylic acid such as di-tert-butylsalicylic acid chromium complex and di-tert-butylsalicylic acid zinc complex are preferable because they are colorless or light-colored and do not affect the color tone of the toner. As the charge control agent, a charge control resin (CCR) can also be suitably used. Examples of the charge control resin include a styrene acrylic polymer obtained by copolymerization of a monomer containing a quaternary ammonium salt, an organic fluorine-based monomer, a sulfonic acid group-containing monomer, a phenylmaleimide monomer, and the like.
The preferred lower limit of the amount of these charge control agents is usually 0.1 parts by weight with respect to 100 parts by weight of the toner resin composition, and the preferred upper limit is 10 parts by weight.

As said magnetic body, brand name "TAROX BL series" (made by Titanium Industry Co., Ltd.), brand name "EPT series", brand name "MAT series", brand name "MTS series" (all made by Toda Kogyo Co., Ltd.) , Product name "DCM series" (manufactured by Dowa Iron Powder Co., Ltd.), product name "KBC series", product name "KBI series", product name "KBF series", product name "KBP series" (all manufactured by Kanto Denka Kogyo Co., Ltd.) ), Trade name “Bayoide E series” (manufactured by Bayer AG), and the like.
In the conventional toner, when the magnetic material is added, the resin ratio in the toner is lower than that of the non-magnetic toner, and the nip pressure of the fixing roller is increased, thereby exhibiting high temperature offset resistance. Although it tends to be difficult, the toner of the present invention can exhibit good high-temperature offset resistance even when a magnetic material is added. One of the reasons why excellent high temperature offset resistance can be realized even when a magnetic material is added in this way is that, in the resin composition for toner of the present invention, isocyanate groups are highly dispersed in the resin. Accordingly, the release agent having a polar group added to the toner is also well dispersed.
As described above, the resin composition of the present invention can exhibit good high-temperature offset resistance in a magnetic one-component toner considered to have the lowest ratio of the resin to the whole toner among the commonly used toners. It can be applied to any toner.

Examples of the rubbery polymer include natural rubber, polyisoprene rubber, polybutadiene rubber, nitrile rubber (acrylonitrile-butadiene copolymer), chloroprene rubber, butyl rubber, acrylic rubber, polyurethane elastomer, silicone rubber, and ethylene-propylene copolymer. , Ethylene-propylene-diene copolymer, chlorosulfinated polyethylene, ethylene vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, chlorinated polyethylene, epichlorohydrin rubber, nitrile isoprene Synthetic rubber such as rubber, elastomer such as polyester elastomer, urethane elastomer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, steel Down - ethylene butylene - styrene block copolymer, styrene - ethylene propylene - block copolymer of an aromatic hydrocarbon and a conjugated diene hydrocarbon such as styrene block copolymers. In addition, a styrene-butadiene block copolymer, a styrene-isoprene block copolymer, etc. may be mixed with the block copolymer, and these hydrogenated substances may be mixed.
Further, a rubbery polymer comprising a block copolymer of an aromatic hydrocarbon having a polar group such as a hydroxyl group, a carboxyl group, an aldehyde group, a sulfonyl group, a cyano group, a nitro group, or a halogen group and a conjugated diene is used as a toner. It is preferable because of its excellent affinity with. These block copolymers having polar groups at the ends can be obtained by living polymerization.
The rubbery polymer can improve the resin strength of the resin contained in the toner. Therefore, the toner containing the rubber-like polymer can prevent the filming phenomenon of the toner, and a toner suitable for the non-magnetic one-component toner requiring high resin strength can be obtained.

Examples of the carrier include simple metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, and rare earth, alloys, oxides, and ferrites. The surface of the carrier may be oxidized. Carrier surface is polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone polymer, polyester, metal complex of di-tert-butylsalicylic acid, styrene polymer, acrylic polymer, polyamide, polyvinyl butyral, nigrosine base May be coated with a functional dye, silica powder, alumina powder or the like. By coating the carrier, preferable triboelectric chargeability can be imparted to the carrier.

The cleaning property improving agent is not particularly limited as long as the fluidity of the toner is improved by mixing with the toner particles. When the fluidity of the toner is improved, the toner is less likely to adhere to the cleaning blade. For example, fluorine polymer powder such as vinylidene fluoride polymer, acrylic polymer powder such as acrylic ester polymer, fatty acid metal salt powder such as zinc stearate, calcium stearate, lead stearate, zinc oxide powder, titanium oxide powder, etc. Examples thereof include metal oxide powder, fine powder silica powder, silica powder surface-treated with a silane coupling agent, titanium coupling agent, silicon oil, and the like, fumed silica, and the like. In addition, as the cleaning property improver, a sphere having a particle diameter of 0.05 to 0.5 μm made of an acrylic polymer, a styrene polymer, or the like can be suitably used.

The toner of the present invention preferably has a peak at a position where the weight average molecular weight is 2000 or less as measured by GPC. This improves the fixability. The toner of the present invention preferably has a peak at a position where the weight average molecular weight is 10,000 or more as measured by GPC. Thereby, water resistance improves.

The particle size of the toner of the present invention is not particularly limited, but particularly high image quality can be obtained when it is 5 μm or less.
The moisture content of the toner of the present invention is not particularly limited, but a preferred lower limit is 0.01% by weight and a preferred upper limit is 0.2% by weight. If it is less than 0.01% by weight, production becomes difficult due to problems in production, and if it exceeds 0.2% by weight, sufficient charging stability may not be obtained.
The repose angle of the toner of the present invention is not particularly limited, but the preferred lower limit of the repose angle at 23 ° C. and 60% humidity is 1 degree, and the preferred upper limit is 30 degrees. If it is less than 1 degree, handling of the toner may be difficult, and if it exceeds 30 degrees, the fluidity of the toner may be insufficient. The angle of repose of the toner can be measured by, for example, a powder tester (for example, PT-N type manufactured by Hosokawa Micron Corporation).

The surface roughness of the toner of the present invention is not particularly limited, but a preferred lower limit is 0.01 μm and a preferred upper limit is 2 μm. If it is less than 0.01 μm, it may be difficult to perform printing, and if it exceeds 2 μm, the surface gloss of the resulting image may be insufficient. The surface roughness can be measured by a method defined in JIS B 0601 as a method for measuring the arithmetic average roughness (Ra) of a printed portion of an image printed using the toner of the present invention.

The toner of the present invention can express good fixability in a wide range from low temperature to high temperature, and is excellent in both low temperature fixability, high temperature offset resistance and blocking resistance. It is economical because the time until it becomes possible can be shortened, and furthermore, the sharpness of the image can be maintained even when the temperature of the roller is lowered, so that the printing speed can be increased. . The toner of the present invention is excellent in image reproducibility.

In addition, the toner of the present invention may be fixed by a fixing roller to which a release oil is applied, but can exhibit good fixability even if the release oil is not applied to the fixing roller.

In the present invention, the branched polyester and the isocyanate compound are reacted, and the unreacted branched polyester is uniformly mixed with the crosslinked structure having an appropriate crosslinking density. A toner resin composition and a toner capable of obtaining a toner having an excellent balance of offset properties and an excellent image quality.

In order to describe the present invention in more detail, examples will be given below, but the present invention is not limited to these examples.

Example 1
(1) Production of branched polyester A distillation column, a water separator, a nitrogen gas introduction tube, a thermometer and a stirring measure are installed in a conventional method in a 60 L reaction vessel, and terephthalic acid is used as a dicarboxylic acid component in a nitrogen gas atmosphere. 90 moles, 5 moles of isophthalic acid as bending monomer component, 5 moles of phthalic anhydride, 2.5 moles of trivalent or higher polyvalent monomer, 2.5 moles of trimellitic acid, 100 moles of neopentyl glycol as branching monomer component, other diols As an esterification condensation catalyst, 100 mol of ethylene glycol and 0.05 mol of titanium tetrabutoxide (TBB) as an esterification condensation catalyst were charged, and an esterification reaction was carried out at 200 ° C. while distilling water produced from the distillation column. The esterification reaction was completed when water no longer distilled from the distillation column.
After completion of the esterification reaction, the opening to the distillation column of the 60 L reaction vessel is closed, the line from the vacuum pump is opened, the inside of the reaction system is decompressed to 5 mmHg or less, and the condensation reaction is carried out at 240 ° C. with a stirring rotational speed of 60 rpm. The free diol produced by the condensation reaction was distilled out of the reaction system to obtain a branched polyester.
(2) Production of Resin Composition for Toner 97.5 parts by weight of the obtained branched polyester was continuously fed to a twin screw extruder (Ikegai, L / D = 37) using a quantitative feeder, and barrel After melt-kneading at a temperature of 120 ° C., volatile components were removed from the first vent port of the twin screw extruder.
Next, 2.5 parts by weight of polymer type MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) having two or more isocyanate groups in one molecule is continuously supplied from the second vent port of the twin screw extruder, A resin composition for toner was obtained by melt-kneading at a barrel temperature of 170 ° C.
(3) Production of toner 100 parts by weight of the obtained resin composition for toner, 1 part by weight of charge control agent (S-34, manufactured by Orient Chemical Co.), 5 parts by weight of carbon black (MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) Then, 3.5 parts by weight of carnauba wax (melting point: 83 ° C.) was sufficiently mixed with a Henschel mixer, melt-kneaded at 130 ° C., cooled, and coarsely pulverized. Thereafter, it was finely pulverized with a jet mill (Lab Jet, manufactured by Nippon Pneumatic Co., Ltd.) to obtain a toner powder having an average particle size of about 8 to 12 μm. Further, this toner powder was classified by a classifier (MDS-2, manufactured by Nippon Pneumatic Co., Ltd.) to obtain a toner fine powder having an average particle diameter of about 10 μm. A toner was manufactured by uniformly mixing (externally adding) 1.0 part by weight of hydrophobic silica (R972, manufactured by Nippon Aerosil Co., Ltd.) to 100 parts by weight of the toner fine powder.

(Example 2)
(1) Production of branched polyester A branched polyester was obtained in the same manner as in Example 1.
(2) Manufacture of resin composition for toner The addition amount of the obtained branched polyester was 97.9 parts by weight, and the addition amount of polymeric MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) was 2.1 parts by weight. Except for the above, a toner resin composition was obtained in the same manner as in Example 1.
(3) Production of Toner A toner was produced in the same manner as in Example 1 using the obtained resin composition for toner.

(Example 3)
(1) Production of branched polyester A branched polyester was obtained in the same manner as in Example 1, except that the amount of trimellitic acid added was 4.3 mol.
(2) Manufacture of resin composition for toner The addition amount of the obtained branched polyester was 98.5 parts by weight, and the addition amount of polymeric MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) was 1.5 parts by weight. Except for the above, a toner resin composition was obtained in the same manner as in Example 1.
(3) Production of Toner A toner was produced in the same manner as in Example 1 using the obtained resin composition for toner.

Example 4
In the production of the branched polyester, a branched polyester was obtained in the same manner as in Example 1 except that the amount of trimellitic acid added was 1.6 mol.
Using the resulting branched polyester, a toner resin composition and a toner were produced in the same manner as in Example 1.

(Example 5)
In the production of the branched polyester, a branched polyester was obtained in the same manner as in Example 1 except that the amount of trimellitic acid added was 4.7 mol.
Using the resulting branched polyester, a toner resin composition and a toner were produced in the same manner as in Example 1.

(Example 6)
(1) Production of low molecular weight linear polyester A distillation column, a water separator, a nitrogen gas inlet tube, a thermometer and a stirrer are installed in a 60 L reaction vessel according to a conventional method, and as a dicarboxylic acid component in a nitrogen gas atmosphere. 90 mol of dimethyl terephthalate, 10 mol of dimethyl isophthalate, 100 mol of neopentyl glycol as the diol component, 100 mol of ethylene glycol, 0.05 mol of titanium tetrabutoxide as the esterification condensation catalyst, and water and methanol produced at 200 ° C Was esterified while distilling from the distillation column. The esterification reaction was completed when water no longer distilled from the distillation column.
After completion of the esterification reaction, the opening to the distillation column of the 60 L reaction vessel is closed, the line from the vacuum pump is opened, the inside of the reaction system is reduced to 5 mmHg or less, and the condensation reaction is carried out at 240 ° C. with a stirring rotation speed of 60 rpm. And free diol produced by the condensation reaction was distilled out of the reaction system to obtain a low molecular weight linear polyester.
(2) Production of Toner Resin Composition A toner resin composition and a toner were produced in the same manner as in Example 1 except that 50 parts by weight of branched polyester and 50 parts by weight of low molecular weight linear polyester were used.

(Comparative Example 1)
(1) Manufacture of branched polyester Except that the addition amount of trimellitic acid was 4.7 mol, the addition amount of neopentyl glycol as a branching monomer component was 45 mol, and the addition amount of ethylene glycol as another diol was 45 mol. In the same manner as in Example 1, a branched polyester was obtained.
(2) Production of Toner Resin Composition The amount of branched polyester obtained was 94.8 parts by weight, and the amount of polymeric MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) was 5.2 parts by weight. Except for the above, a toner resin composition was obtained in the same manner as in Example 1.
(3) Production of Toner A toner was produced in the same manner as in Example 1 using the obtained resin composition for toner.

(Comparative Example 2)
(1) Production of linear polyester A distillation column, a water separator, a nitrogen gas inlet tube, a thermometer and a stirring measure are installed in a conventional method in a 60 L reaction vessel, and terephthalic acid is used as a dicarboxylic acid component in a nitrogen gas atmosphere. 90 mol, 10 mol of isophthalic acid as a bending monomer component, 100 mol of neopentyl glycol as a branched monomer component, 100 mol of ethylene glycol as another diol, and 0.05 mol of titanium tetrabutoxide (TBB) as an esterification condensation catalyst The esterification reaction was carried out at 0 ° C. while distilling the water produced from the distillation column. The esterification reaction was completed when water no longer distilled from the distillation column.
After completion of the esterification reaction, the opening to the distillation column of the 60 L reaction vessel is closed, the line from the vacuum pump is opened, the inside of the reaction system is decompressed to 5 mmHg or less, and the condensation reaction is carried out at 240 ° C. with a stirring rotational speed of 60 rpm. The free diol produced by the condensation reaction was distilled out of the reaction system to obtain a linear polyester.
(2) Production of resin composition for toner The amount of linear polyester obtained was 96.3 parts by weight, and the amount of polymeric MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) was 3.7 parts by weight. Except for the above, a toner resin composition was obtained in the same manner as in Example 1.
(3) Production of Toner A toner was produced in the same manner as in Example 1 using the obtained resin composition for toner.

(Comparative Example 3)
(1) Production of branched polyester A branched polyester was obtained in the same manner as in Example 1 except that the amount of trimellitic acid added was 5.9 mol.
(2) Manufacture of resin composition for toner The addition amount of the obtained branched polyester was 98.5 parts by weight, and the addition amount of polymeric MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) was 1.5 parts by weight. In the same manner as in Example 1, a toner resin composition was obtained.
(3) Production of Toner A toner was produced in the same manner as in Example 1 using the obtained resin composition for toner.

(Evaluation)
The branched polyesters, toner resin compositions or toners prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were evaluated by the following methods. The results are shown in Table 1.

[Measurement of hydroxyl value of branched polyester]
About the obtained branched polyester, the hydroxyl value was calculated | required by the method based on JISK0070.

[Measurement of acid value of branched polyester]
About the obtained branched polyester, the acid value was calculated | required by the method based on JISK6751 except having used tetrahydrofuran (THF) instead of ethyl alcohol.

[Measurement of molecular weight distribution of branched polyester and resin composition for toner]
As a GPC measuring device, HTR-C manufactured by Nihon Millipore Limited is used, and KF-800P (1), KF-806M (2), KF-802.5 (1) manufactured by Showa Denko K.K. Were used in series, and the peak molecular weight of the branched polyester, the weight average molecular weight (Mw), and the number average molecular weight (Mn) of the branched polyester and the resin composition for toner were measured. The measurement conditions were as follows: the temperature was 40 ° C., the sample was a 0.2 wt% THF solution (passed through a 0.45 μm filter), the injection amount was 100 μL, the carrier solvent was THF, and standard polystyrene was used as the calibration sample.

[Area ratio measurement]
The molecular weight distribution curve of the branched polyester obtained by measuring the molecular weight distribution of the toner resin composition described above was used to determine the total peak area of the toner resin composition, and then the molecular weight distribution of the branched polyester described above. Based on the peak molecular weight of the branched polyester obtained by the measurement, the peak area in the range below the peak molecular weight of the branched polyester was determined. From these areas, the area ratio of the peak area within the range of the molecular weight below the peak molecular weight of the branched polyester to the total peak area was calculated.

[Measurement of glass transition temperature (Tg)]
The resin composition for toner was measured according to JIS K 7121 using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC-6200R) at a heating rate of 10 ° C./min. 3 “How to determine glass transition temperature”) was determined.

[Measurement of flow softening temperature]
Using a Koka flow tester (Shimadzu Corporation, CFT-500 type), load 20 kg / cm ² , orifice 1 mmφ × 1 mm, preliminary temperature 60 ° C., preliminary time 5 minutes, chart speed 20 mm / minute, plunger 1. Under the conditions of 0 cm ² and a temperature increase rate of 6 ± 0.5 ° C./min, 1.0 g of a measurement sample passing through a JIS standard sieve having an opening of 1.19 mm was melted out, and as shown in FIG. The temperature Tf when a plunger lowering amount h / 2 intermediate between the plunger lowering amount at the start of outflow of the resin and the plunger lowering amount at the time of stopping the resin outflow was measured.

[Measurement of relaxation modulus]
The toner resin composition was melted and then formed into a disk shape having a diameter of 25 mm and a height of 1 mm, and this was used as a test sample. This was attached to a disk-disk jig having a diameter of 25 mm, and a shear strain was applied using a relaxation elastic modulus measuring apparatus (ARES, manufactured by T.A. Instruments Co., Ltd.) at 170 ° C. and initial shear strain of 450%. Then, the relaxation modulus G _{170 ° C.} (0.1) after 0.1 seconds was measured.

[Evaluation of blocking properties]
Take 10 g of toner in a 100 mL sample bottle and leave it in a thermostatic bath at 50 ° C. for 8 hours. When there was an aggregate, the weight (% by weight) of the aggregate with respect to the toner weight was determined.

[Filming evaluation]
After 10,000 sheets were printed, whether or not toner was adhered to the photosensitive roller was visually observed, and if no toner adhesion was observed, it was evaluated that there was no filming.

[Measurement of high temperature offset temperature and low temperature offset temperature]
A developer was prepared by mixing 6.5 parts by weight of the toner obtained in Examples 1 to 3 and Comparative Example 1 with 93.5 parts by weight of an iron powder carrier having an average particle size of 50 to 80 μm. As an electrophotographic copying machine, a UBIX4160AF manufactured by Konica was used so that the set temperature of the heat fixing roller could be changed up to 250 ° C.
The set temperature of the heat fixing roller was changed stepwise to obtain a copy in which the unfixed toner image was fixed on the transfer paper by the heat fixing roller at each set temperature.
It was observed whether the blank portion of the obtained copy and the fixed image were stained with toner, and a temperature region where no contamination occurred was defined as a non-offset temperature region. Further, the maximum value in the non-offset temperature region was set as the high temperature offset temperature, and the minimum value was set as the low temperature offset temperature.
The toner of Example 7 was not mixed with the iron powder carrier, and was drawn with a printer (ES-6020, manufactured by Kyocera Mita Co., Ltd.) using 100 parts by weight of the toner as a developer, immediately before fixing. The machine was stopped and an image before fixing was obtained. The obtained pre-fix image was subjected to the same operation as described above using a heat fixing roller of UBIX4160AF to obtain a copy, and the high temperature offset temperature and the low temperature offset temperature were measured.

[Measurement of minimum fixing temperature of toner]
Copying was performed by changing the set temperature of the heat fixing roller of the electrophotographic copying machine step by step, and the blank portion and the fixed image were not stained with toner without causing the fog on the blank portion and the fixed image. When the fixed image of the copy was rubbed with a typewriter member, the case where the decrease in density of the fixed image was less than 10% was determined to be good fixing, and the minimum temperature at that time was determined.
The image density was measured using a Macbeth photometer.

[Confirmation of image quality (presence / absence of fog, image density)]
An unfixed image was formed in the same manner as the test for measuring the high temperature offset temperature and the low temperature offset temperature, the 100th image was fixed, and the presence or absence of fog was visually confirmed. The case where the occurrence of fog is at a level where there is no problem is defined as no fog, and the case where fog which causes a problem occurs is defined as fog. The image density was measured using a Macbeth photometer.

ADVANTAGE OF THE INVENTION According to this invention, the resin composition for toners and toner which can obtain the toner which is excellent in low temperature fixability, high temperature offset resistance, and image quality can be provided.

3 is a molecular weight distribution curve obtained when the resin composition for toner of the present invention is measured by GPC. 3 is a molecular weight distribution curve obtained when the resin composition for toner of the present invention is measured by GPC. It is a typical flowchart which shows the relationship between plunger fall amount and time (temperature) at the time of calculating | requiring the flow softening point Tf by a uniform-speed heating method.

Explanation of symbols

x Peak molecular weight of branched polyester before reaction

Claims (4)

A resin composition for a toner obtained by reacting a branched polyester having a hydroxyl value of 5 to 100 with an isocyanate compound having two or more isocyanate groups in one molecule,
Containing unreacted branched polyester having a molecular weight equal to or lower than the peak molecular weight of the branched polyester before the reaction,
When the molecular weight distribution of the tetrahydrofuran solubles was measured using gel permeation chromatography, the peak area in the range below the peak molecular weight of the branched polyester before the reaction was 20 to 45% with respect to the total peak area. A toner resin composition, comprising: The resin composition for toner according to claim 1, wherein the branched polyester has an average degree of branching represented by the following formula (1) of 2.1 to 7.0.

In the formula (1), Bu is the average degree of branching, NOH is the number of hydroxyl groups per gram of branched polyester, N is the number of molecules per gram of branched polyester, Mn is the number average molecular weight, OHV is the hydroxyl value of the branched polyester, 56 .1 represents the molecular weight of potassium hydroxide. The resin composition for toner according to claim 1, wherein the isocyanate compound has three or more isocyanate groups in one molecule. A toner comprising the toner resin composition according to claim 1, 2 or 3.

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