JP2007025622A - Method for preparing resin composition for toner, resin composition for toner and toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing a resin composition for toner excellent in low-temperature fixability and hot-offset resistance, such a resin composition for toner and a toner. <P>SOLUTION: The method for preparing the resin composition for toner by uniform mixing of a crosslinked polyester and a low-molecular-weight linear polyester includes a step of putting a branched polyester having a number average molecular weight of 2,000-5,000 and an isocyanate compound having two or more isocyanate groups within a molecule in an extrusion kneading machine and initiating a crosslinking reaction, and a step of further putting the low-molecular-weight linear polyester before completion of the crosslinking reaction and carrying out kneading. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for producing a resin composition for a toner capable of obtaining a toner having excellent low-temperature fixability and high-temperature offset resistance, a resin composition for toner, and a toner.

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.

In conventional polyester-based toners, a polyfunctional monomer having three or more functional groups is usually copolymerized to form a chemically cross-linked structure in the polymer to maintain high temperature offset resistance. However, in such a method, since a low molecular weight polymer to a high molecular weight cross-linked polymer exist and the molecular weight distribution becomes wide, it is difficult to achieve both high temperature offset resistance and low temperature fixability. .

In Patent Document 1, a crystalline polyester resin containing 50 mol% or more of terephthalic acid and a unit derived from a linear alkylene glycol having 2 to 6 carbon atoms is used as a binder resin for the toner, based on all the monomer units used. It has been proposed.
However, in this technique, since only the crystalline polyester resin is used, it is difficult to maintain the high-temperature offset resistance and the blocking resistance without impairing the low-temperature fixability because the temperature range capable of fixing is narrow.

In Patent Document 2, as a toner binder resin, a trivalent or higher polyvalent monomer, an aromatic dicarboxylic acid, and an aliphatic alcohol containing 50 mol% or more of a branched aliphatic alcohol are polymerized. It has been proposed to use an amorphous polyester resin.
However, this technique also uses a trivalent or higher polyvalent monomer, dicarboxylic acid, diol, and the like, so that the molecular weight distribution of the resulting amorphous polyester is widened, and the low-temperature fixability is not particularly satisfactory.

Further, Patent Document 3 is obtained by reacting a dibasic carboxylic acid, a diol, and a triol, obtained by reacting a polyester having a hydroxyl value of 6 to 100 with a predetermined amount of isocyanate, and having a gel fraction within a predetermined range. The manufacturing method of the binder resin which is the inside is disclosed. However, in such a production method, a polyester having a wide molecular weight distribution from a low molecular weight polyester to a high molecular weight urethane-modified polyester is produced, so that both low temperature fixability and high temperature offset resistance can be achieved. There wasn't.

In order to realize a toner excellent in both low-temperature fixability and high-temperature offset resistance against these problems, Patent Document 4 discloses a non-linear material having a tetrahydrofuran insoluble content of 15% by weight or more and having a high softening point. A toner binder containing a polyester and a polyester with a low softening point is disclosed.
In such a toner binder, a non-linear polyester having a high softening point and a polyester having a low softening point are separately produced, and these are kneaded using a powder mixing method, a melt mixing method, or the like. However, in such a kneading method, the non-linear polyester having a high softening point and the polyester having a low softening point are not uniformly mixed, resulting in insufficient high temperature offset resistance or low temperature fixability of the obtained toner. was there.
Japanese Patent No. 2988703 Japanese Patent No. 2704282 Japanese Patent No. 29986820 JP 2001-265056 A

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing a resin composition for a toner, a toner resin composition, and a toner capable of obtaining a toner having excellent low-temperature fixability and high-temperature offset resistance. .

The present invention relates to a method for producing a resin composition for a toner in which a crosslinked polyester and a low molecular weight linear polyester are uniformly mixed, and the branched polyester having a number average molecular weight of 2000 to 5000 is added to an extrusion kneader. A resin composition for a toner comprising a step of injecting two or more isocyanate compounds into one molecule to start a crosslinking reaction, and a step of further introducing a low molecular weight linear polyester and kneading before the crosslinking reaction is completed. It is a manufacturing method of a thing.
The present invention is described in detail below.

As a result of intensive studies, the inventors of the present invention have made low molecular weight linear from the start to the completion of the crosslinking reaction between the branched polyester and the isocyanate compound in the production of a resin composition for a toner using an extrusion kneader. By introducing the polyester, the production of the crosslinked polyester and the kneading of the crosslinked polyester and the low molecular weight linear polyester can be performed in a continuous process, and the crosslinked polyester and the low molecular weight linear polyester can be uniformly formed. Since they can be mixed, it has been found that a toner resin composition capable of producing a toner having both low-temperature fixability and high-temperature offset resistance can be produced, and the present invention has been completed.

In the method for producing a resin composition for a toner of the present invention, first, a branched polyester having a number average molecular weight of 2000 to 5000 (hereinafter also simply referred to as a branched polyester) and two in a molecule are placed in an extrusion kneader. The step of starting the crosslinking reaction by introducing the isocyanate compound having the above isocyanate group (hereinafter also simply referred to as an isocyanate compound) is performed.
When the branched polyester and the isocyanate compound are cross-linked, the cross-linking density is moderately suppressed as compared to the case where a polyvalent monomer and a dicarboxylic acid or diol are copolymerized to form a cross-linked structure, Since a more uniform cross-linking is formed, the resulting cross-linked polyester has a molecular weight distribution that is not too wide, and a resin composition for a toner that can produce a toner having an excellent balance between low-temperature fixability and high-temperature offset resistance. be able to.

The extrusion kneader is not particularly limited. However, a uniaxial or biaxial extrusion kneader is preferable because the cross-linked polyester and the low molecular weight linear polyester can be kneaded satisfactorily and continuous production is possible. Is preferable, and a twin-screw extrusion kneader is more preferable.

An example of an extrusion kneader used in the method for producing a resin composition for a toner of the present invention is shown in FIG.
As shown in FIG. 1, the extrusion kneader 1 has a screw (not shown) inside and two raw material charging ports. When used in the present invention, the extrusion kneader 1 is branched from the hopper (A). A polyester and an isocyanate compound are added to initiate a crosslinking reaction, and a low molecular weight linear polyester can be added from the side feeder (B) during the crosslinking reaction.

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 cross-linking reaction and the dispersibility of the low molecular weight linear polyester may be insufficient. If it exceeds 30 minutes, the generated cross-linked polyester is thermally decomposed or thermally deteriorated, thereby preventing high temperature offset. 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. If it is less than 100 ° C., the crosslinking reaction is difficult to proceed, the formation of the crosslinked polyester may be insufficient, or the crosslinked polyester and the low molecular weight linear polyester may not be uniformly mixed. The generated crosslinked polyester may not be improved in high temperature offset resistance due to thermal decomposition or thermal degradation.

In the method for producing a resin composition for a toner of the present invention, the branched polyester may be reacted with an isocyanate compound 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.
In addition, it does not specifically limit as a method to make it react in presence of the said water | moisture content, For example, the method of using the branched polyester containing water as a raw material, the method of throwing in water simultaneously with a raw material, etc. are mentioned.

The method for producing a resin composition for a toner of the present invention includes a step of adding and kneading a low molecular weight linear polyester before the crosslinking reaction between the branched polyester and the isocyanate compound is completed.
By introducing the low molecular weight linear polyester, the low-temperature fixability of the obtained toner can be improved. In addition, by introducing the low molecular weight linear polyester before the crosslinking reaction is completed, the low molecular weight linear polyester is uniformly mixed as compared with the case where the low molecular weight linear polyester is introduced after the crosslinking reaction is completed. In addition, by producing a toner using such a resin composition for a toner, a toner having both high-temperature offset resistance and low-temperature fixability can be obtained.
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.

In the method for producing a resin composition for a toner of the present invention, before the crosslinking reaction between the branched polyester and the isocyanate compound is completed, the gel content of the mixture after the branched polyester and the isocyanate compound are added. The rate is in the range of 10 to 30%. If it is less than 10%, crosslinking is insufficient, so that the molecular weight distribution of the toner resin composition obtained after charging and kneading the low molecular weight linear polyester becomes wide, and if it exceeds 30%, it is obtained. The dispersibility of the low molecular weight linear polyester in the toner resin composition is lowered.

In the present invention, it is preferable to further add a polyhydric alcohol in the step of injecting the branched polyester and the isocyanate compound to start the crosslinking reaction and / or the step of injecting and kneading the low molecular weight linear polyester. 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.

Another embodiment of the present invention is a method for producing a resin composition for a toner, in which a crosslinked polyester and a low molecular weight linear polyester are uniformly mixed, and the number average molecular weight is 2000 to 5000 in an extrusion kneader. A branched polyester, a linear polyester having a number average molecular weight of 2000 to 10,000, and a step of injecting two or more isocyanate compounds into one molecule to start a crosslinking reaction, and further lower before the crosslinking reaction is completed. There is a method for producing a resin composition for a toner having a step of adding and kneading a molecular weight linear polyester.

The preferable lower limit of the addition amount of the linear polyester is 10 parts by weight with respect to 100 parts by weight of the branched polyester, and the preferable upper limit is 900 parts by weight. If the amount is less than 10 parts by weight, the effect of adjusting the crosslinking density to an appropriate level may not be exhibited. If the amount exceeds 900 parts by weight, the crosslinking density is insufficient.
In another embodiment of the present invention, the branched polyester, linear polyester and isocyanate compound may be reacted in the presence of moisture.
The present invention in another embodiment is the same as the resin composition for toners of the present invention except that the above linear polyester is added simultaneously with the branched polyester and the isocyanate compound, and the description thereof is omitted.

By using the method for producing a resin composition for a toner of the present invention, a resin composition for a toner having both low temperature fixability and high temperature offset resistance, in which a crosslinked polyester and a low molecular weight linear polyester are uniformly mixed, is obtained. Obtainable.
A resin composition for a toner containing a crosslinked polyester and a low molecular weight linear polyester, having a swelling ratio measured by a method of immersing in tetrahydrofuran, shaking for 16 hours at room temperature, and filtering with a 200 mesh wire mesh filter. When a shear strain of 450% was applied under conditions of 500 to 4000%, a flow softening point of 100 to 160 ° C. and 170 ° C., a shear strain represented by the following formula (1) was applied to give 0.02 A resin composition for toner in which the slope K of the relaxation elastic modulus curve from 0.1 second to 0.1 second later is from 5 to 26 is also one aspect of the present invention. Such a resin composition for toner can also be produced by the method for producing a resin composition for toner of the present invention.

The resin composition for toner of the present invention has a lower limit of swelling of 500% and an upper limit of 4000% as measured by a method of immersing in tetrahydrofuran, shaking for 16 hours at room temperature, and filtering with a 200 mesh wire mesh filter. .
Since the swelling rate is related to the crosslink density of the cross-linked polyester, it indirectly becomes an index indicating the uniformity of mixing of the cross-linked polyester and the linear polyester in the toner resin composition.
Therefore, if the swelling ratio is within the above range, the crosslinked structure is formed at an appropriate density, and the crosslinked polyester and the linear polyester are considered to be uniformly mixed. Both the fixing property and the high temperature offset resistance can be achieved.
If it is less than 500%, the crosslinking density becomes too high and the high-temperature offset resistance is improved, but the low-temperature fixability is lowered. If it exceeds 4000%, the crosslink density becomes too low, and accordingly, the high temperature offset resistance becomes insufficient. A preferred lower limit is 700% and a preferred upper limit is 3500%.

The toner resin composition of the present invention is divided into a soluble component (THF soluble component) capable of GPC measurement and an insoluble component (gel component) by dipping in tetrahydrofuran, and the above THF soluble component. Is composed of a component having a weight average molecular weight of less than 40,000 in GPC measurement and a component having a weight average molecular weight of 40,000 or more in GPC measurement, and a component having a weight average molecular weight in the GPC measurement of 40,000 or more. The preferable lower limit of the content of is 5% by weight, and the preferable upper limit is 40% by weight. If it is less than 5% by weight, the high-temperature offset resistance may be lowered, and if it exceeds 40% by weight, the low-temperature fixability may be insufficient.

In the toner resin composition of the present invention, the preferable lower limit of the gel fraction is 2%, and the preferable upper limit is 40%. If it is less than 2%, the high-temperature offset resistance may be lowered, and if it exceeds 40%, the low-temperature fixability may be insufficient.
In the present specification, the gel fraction means the gel content. For example, the weight of the toner resin composition immersed in tetrahydrofuran and then dried, and the toner composition before immersion. It can obtain | require by measuring ratio with the weight of a resin composition.

In the resin composition for toner of the present invention, the lower limit of the flow softening point is 100 ° C., and the 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 is deteriorated. A preferable upper limit is 150 degreeC and a more preferable upper limit is 145 degreeC.
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 applied with a shear strain of 450% under the condition of 170 ° C., 0.02 seconds after applying the shear strain represented by the above formula (1) (0.02 When the peak position of the relaxation elastic modulus curve is between 0.1 seconds and 0.1 second later, the lower limit of the gradient K of the relaxation elastic modulus curve 0.1 seconds later is 5 and the upper limit is 26. is there.

In the formula, G (T) represents a relaxation elastic modulus after T seconds after applying a shear strain. T represents the time at the peak position of the relaxation elastic modulus curve between 0.02 seconds and 0.1 seconds later. If there is a peak position of the relaxation modulus curve before 0.02 seconds, T is set to 0.02. G (0.1) represents the relaxation elastic modulus after 0.1 seconds after applying a shear strain.

The gradient K of the relaxation elastic modulus curve represents the elastic behavior of the substance, and the closer to 0, the closer to rubber elasticity. Therefore, it is considered that the fact that the slope K of the relaxation elastic modulus curve is within the above range means that a sufficient cross-linked structure is formed and rubber-like properties are expressed. Therefore, the toner resin composition of the present invention in which the slope K of the relaxation elastic modulus curve is 5 to 26 exhibits good high temperature offset resistance. If the slope K of the relaxation elastic modulus curve is less than 5 or exceeds 26, it is considered that the formation of the crosslinked structure is insufficient, and the high temperature offset resistance is also insufficient. A preferred upper limit is 20, and a more preferred upper limit is 18.
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 of a predetermined size as a test sample, and using a relaxation elastic modulus measuring device (for example, Rheometrics Co., Ltd.). It can be measured using RMS-800 manufactured by

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 resin composition for toner of the present invention contains a crosslinked polyester.
By containing the crosslinked polyester, the high-temperature offset resistance of the obtained toner is improved.

The crosslinked polyester is preferably a product obtained by reacting a branched polyester having a number average molecular weight of 2000 to 5000 with two or more isocyanate compounds in one molecule. The cross-linked polyester thus obtained has a moderately low cross-linking density and more uniform cross-linking as compared to the case where a polyvalent monomer is copolymerized with a dicarboxylic acid or diol to form a cross-linked structure. As a result, the toner resin composition can be produced in which the molecular weight distribution is not excessively wide and a toner having an excellent balance between low-temperature fixability and high-temperature offset resistance can be produced.

The branched polyester is preferably one obtained by reacting dicarboxylic acid, diol and tricarboxylic acid.
By using the above tricarboxylic acid, the distance between the hydroxyl groups that are crosslinking reaction points of the resulting branched polyester is increased, and steric hindrance is reduced, so that a branched polyester excellent in reactivity with the isocyanate compound can be obtained. it can. Also, the crosslinked polyester obtained after the crosslinking reaction also has a moderately wide crosslinking density. Therefore, the resin composition for a toner obtained after the low molecular weight linear polyester is added and kneaded is composed of the crosslinked polyester and the low molecular weight line. The polyester is uniformly mixed.
In the present specification, the branched polyester refers to a polyester having a branched structure in the polyester skeleton.

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.

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.

The preferable lower limit of the addition amount of the tricarboxylic acid is 0.5 mol% with respect to the addition amount of the dicarboxylic acid, 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.

In addition to the tricarboxylic acid, a trivalent or higher polyvalent carboxylic acid or a trivalent or higher polyhydric alcohol may be added.
Examples of the trivalent or higher polyvalent carboxylic acid include pyromellitic acid, 1,2,7,8-octanetetracarboxylic acid and acid anhydrides thereof in addition to the tricarboxylic acid.

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-trihydroxy Examples include methylbenzene. In addition, these may be used independently and may use 2 or more types together.

The branched polyester has a number average molecular weight of 2000 at the lower limit and 5000 as the upper limit. If it is less than 2000, the offset resistance and durability of the obtained toner may be insufficient, and if it exceeds 5000, the obtained toner will be inferior in low-temperature fixability. A preferable upper limit is 4000.

The above-mentioned branched polyester has a preferable lower limit 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 the present specification, the 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 (2). 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 said branching degree can be represented by following formula (3) using Mn and OHV.
Here, when both ends of all the molecules are hydroxyl groups, the degree of branching is 2.0. Therefore, as the degree of branching is larger than 2.0, it indicates that there are more branches.

The preferable lower limit of the hydroxyl value of the branched polyester is 20, and the preferable upper limit is 80.
If it is less than 20, the crosslinking reaction point of the branched polyester is reduced, so that the resulting crosslinked polyester has a low crosslinking density, and high temperature offset resistance may be insufficient. The cross-linking reaction point of the branched polyester is increased, the cross-linking density is increased, and the high-temperature offset resistance is improved, but the low-temperature fixability may be lowered.

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, 2 , Alicyclic diols such as an alkylene oxide adduct of 2-bis (4-hydroxycyclohexyl) propane.

The branched polyester can be obtained, for example, by a method in which the dicarboxylic acid, diol, and tricarboxylic acid are collectively added to a reaction kettle and subjected to a transesterification reaction and a 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.

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.

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. When the amount is less than 0.3 mol, the formation of the crosslinked polyester becomes insufficient, and the high-temperature offset resistance decreases. If it exceeds 3 moles, the excess isocyanate compound that does not participate in crosslinking increases and becomes close to the physical properties of the isocyanate compound itself, so that physical properties such as low-temperature fixability are 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 crosslinked polyester is obtained by reacting a branched polyester having a number average molecular weight of 2000 to 5000, a linear polyester having a number average molecular weight of 2000 to 10,000, and two or more isocyanate compounds in one molecule. May be.
By adding the linear polyester having the number average molecular weight of 2000 to 10,000 (hereinafter also simply referred to as linear polyester) simultaneously with the branched polyester and the isocyanate compound, the crosslinking density of the crosslinked polyester obtained after crosslinking is moderately adjusted. The crosslinked polyester and the 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 lower limit of the number average molecular weight of the linear polyester is 2000, and the 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 preferred lower limit is 2500, and a preferred upper limit is 6000.

The crosslinked polyester is preferably produced by reacting the branched polyester or linear polyester with an isocyanate compound in the presence of moisture. When a crosslinked polyester is produced by such a method, many urea bonds are formed in the molecule of the crosslinked polyester. Since the crosslinked polyester has such a urea bond, it has excellent heat resistance and is difficult to be thermally decomposed even during kneading, so that the resin has 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 or linear 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.

The resin composition for toner of the present invention contains a low molecular weight linear polyester.
By containing the low molecular weight linear polyester, the low-temperature fixability of the obtained toner can be improved. In addition, since the crosslinked polyester and the low molecular weight linear polyester are uniformly mixed, the resin composition for toner of the present invention can obtain a toner having both high temperature offset resistance and low temperature fixability. it can.

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 preferable lower limit of the acid value of the low molecular weight linear polyester is 20, and the preferable upper limit is 80. If it is less than 20, the reactivity with the isocyanate compound becomes too low, and the mixing property between the crosslinked polyester and the low molecular weight linear polyester may deteriorate, and if it exceeds 80, the fluidity of the low molecular weight linear polyester will be deteriorated. As a result, the low-temperature fixability of the resulting toner may be reduced.

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 crosslinked polyester may occur, and a full-area offset without a toner fixing region may occur.

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, di-tert-butylsalicylic acid metal complex, styrenic 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 when measured by gel permeation chromatography. 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 when measured by gel permeation chromatography. 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.

The present invention relates to a method for producing a resin composition for a toner, a toner resin composition, and a toner capable of obtaining a toner having excellent low-temperature fixability and high-temperature offset resistance.

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.
In addition, it was 40 when the hydroxyl value of the obtained branched polyester was measured.

(2) Production of low molecular weight linear polyester A distillation column, a water separator, a nitrogen gas inlet tube, a thermometer and a stirring measure are installed in a conventional manner in a 60 L reaction vessel, and as a dicarboxylic acid component in a nitrogen gas atmosphere. 90 mol of dimethyl terephthalate, 10 mol of dimethyl isophthalate as the bending monomer component, 100 mol of neopentyl glycol, 100 mol of ethylene glycol as the other diol, 0.05 mol of titanium tetrabutoxide (TBB) as the esterification condensation catalyst, 200 The esterification reaction was performed at 0 ° C. while distilling water and methanol 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. And free diol generated by the condensation reaction was distilled out of the reaction system to obtain a low molecular weight linear polyester. In addition, it was 2 when the acid value of the obtained low molecular weight linear polyester was measured.

(3) Production of resin composition for toner 3.2 parts by weight of polymer type MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) having two or more isocyanate groups in one molecule, and 96. 8 parts by weight are continuously fed to a twin-screw extruder (I / K, L / D = 37) using a quantitative feeder, melt-kneaded at a barrel temperature of 170 ° C., and then branched polyester and polymeric MDI are mixed. 100 parts by weight of the obtained low molecular weight linear polyester is supplied from a side feeder provided at a position where the residence time after the supply is 3 minutes, and further melt-kneaded for 5 minutes to obtain a resin composition for toner. Got.
In addition, when the branched polyester and the polymeric MDI were separately kneaded under the same conditions as described above using the extrusion kneader used in the present example, the branched state at the time when the residence time after supply was 3 minutes. The gel fraction of the mixture of polyester and polymeric MDI was 15%, and the gel fraction after 10 minutes was 40%. Therefore, it can be said that the cross-linking reaction between the branched polyester and the polymeric MDI is being performed at the point of 3 minutes after the supply.

(4) Production of toner 100 parts by weight of the obtained resin composition for toner, 1 part by weight of a charge control agent (S-34, manufactured by Orient Chemical Co., Ltd.), 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)
In the production of the resin composition for toner, the same as Example 1 except that the addition amount of the branched polyester was 97 parts by weight and the addition amount of the polymeric MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) was 3 parts by weight. Thus, a resin composition for toner and a toner were produced.

(Example 3)
The production of the resin composition for toner was carried out except that the addition amount of the branched polyester was 96.5 parts by weight and the addition amount of the polymeric MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) was 3.5 parts by weight. In the same manner as in Example 1, a toner resin composition and a toner were produced.

Example 4
In the production of the resin composition for the toner, the amount of the branched polyester added is 97 parts by weight, the polymer compound MDI (MR200, manufactured by Nippon Polyurethane) is used as the isocyanate compound, and the addition of the low molecular weight linear polyester. A toner resin composition and a toner were produced in the same manner as in Example 1 except that the amount was changed to 54 parts by weight.

(Example 5)
(1) Production of low molecular weight linear polyester A distillation column, a water separator, a nitrogen gas inlet tube, a thermometer and a stirring measure are installed in a conventional manner in a 60 L reaction vessel, and as a dicarboxylic acid component in a nitrogen gas atmosphere. 90 mol of dimethyl terephthalate, 10 mol of dimethyl isophthalate as the bending monomer component, 100 mol of neopentyl glycol, 100 mol of ethylene glycol as the other diol, 0.05 mol of titanium tetrabutoxide (TBB) as the esterification condensation catalyst, 200 The esterification reaction was performed at 0 ° C. while distilling water and methanol 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. And free diol generated by the condensation reaction was distilled out of the reaction system to obtain a polyester.
A low molecular weight linear polyester was obtained by adding 13 mol of trimellitic anhydride to the total amount of the obtained polyester and reacting at 200 ° C. for about 1 hour. In addition, it was 53 when the acid value of the obtained low molecular weight linear polyester was measured.

Next, in the production of the resin composition for toner, the amount of the branched polyester added is 96.8 parts by weight, and 3.2 parts by weight of polymer type MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) is used as the isocyanate compound. A resin composition for toner and a toner were produced in the same manner as in Example 1 except that the amount of the obtained low molecular weight linear polyester was changed to 100 parts by weight.

(Example 6)
(1) Production of linear 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 mol of dimethyl, 10 mol of dimethyl isophthalate as the bending monomer component, 100 mol of neopentyl glycol, 100 mol of ethylene glycol as the other diol, and 0.05 mol of titanium tetrabutoxide (TBB) as the esterification condensation catalyst were charged at 200 ° C. The esterification reaction was carried out while distilling the produced water and methanol 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. And free diol generated by the condensation reaction was distilled out of the reaction system to obtain a linear polyester.

(2) Production of toner resin composition and toner 3.5 parts by weight of polymer type MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) having two or more isocyanate groups in one molecule, obtained in Example 1 67.5 parts by weight of branched polyester and 29 parts by weight of linear polyester are continuously fed to a twin-screw extruder (manufactured by Ikegai Co., Ltd., L / D = 37) using a quantitative feeder at a barrel temperature of 170 ° C. After melt-kneading, 100 parts by weight of the low molecular weight linear polyester obtained in Example 1 is charged from a side feeder provided at a position where the residence time after supplying the branched polyester and polymeric MDI is 3 minutes. Then, a resin composition for toner and a toner were produced in the same manner as in Example 1 except that the mixture was further melt-kneaded for 5 minutes.

(Example 7)
To 100 parts by weight of the toner resin composition obtained in Example 1, 100 parts by weight of a magnetic material (BL-62, manufactured by Titanium Industry Co., Ltd.), 1 part by weight of a charge control agent (N-01, manufactured by Orient Chemical Co., Ltd.), 3.5 parts by weight of acid-modified PP wax (melting point: 145 ° C.) was thoroughly 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. To 100 parts by weight of the toner fine powder, 1.0 part by weight of hydrophobic silica (RA200HS, manufactured by Nippon Aerosil Co., Ltd.) was uniformly mixed (externally added) to produce a toner.

(Example 8)
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 4.3 mol. It was 74 when the hydroxyl value of the obtained branched polyester was measured. Further, the degree of branching of the obtained branched polyester was 4.07. Next, in the production of the resin composition for toner, except that the addition amount of the branched polyester was 96.6 parts by weight and the addition amount of the polymeric MDI (44V20, manufactured by Sumika Bayer Urethane Co., Ltd.) was 3.4 parts by weight. In the same manner as in Example 1, a toner resin composition and a toner were produced.

Example 9
In the production of the resin composition for toner, a branched polyester having an addition amount of polymeric MDI having two or more isocyanate groups in one molecule of 4.0% by weight and a water content of 0.6% by weight was used. A toner resin composition and a toner were produced in the same manner as in Example 1 except that.

(Example 10)
In the production of the toner resin composition, a toner resin composition and a toner were produced in the same manner as in Example 1 except that 0.1 part by weight of pentaerythritol was further added as a polyhydric alcohol.

(Comparative Example 1)
In the production of the toner resin composition, a toner resin composition and a toner were obtained in the same manner as in Example 1, except that the low molecular weight linear polyester was not added.

(Comparative Example 2)
In the production of the resin composition for toner, the toner was prepared in the same manner as in Example 1 except that the branched polyester, polymeric MDI, and low molecular weight linear polyester were all put into an extrusion kneader and melt-kneaded for 8 minutes. Resin composition and toner were obtained.

(Comparative Example 3)
In the production of a toner resin composition, a low molecular weight line obtained from a side feeder provided at a position where the residence time after supplying branched polyester and polymeric MDI is 10 minutes (gel fraction 40%) A resin composition for toner and a toner were obtained in the same manner as in Example 1 except that 100 parts by weight of the polyester was added and melted and kneaded for 5 minutes.

(Evaluation)
The toner resin compositions or toners produced in Examples 1 to 10 and Comparative Examples 1 to 3 were evaluated by the following methods. The results are shown in Table 1. For the toner produced in Example 7, only the high temperature offset temperature and the low temperature offset temperature were measured.

[Measurement of molecular weight of resin composition for polyester and 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 connected in series, and the weight average molecular weight (Mw) and the number average molecular weight (Mn) 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.

[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 swelling rate]
0.3 g of the obtained resin composition for toner is weighed into a sample bottle, and 30 g of THF is put in this bottle, shaken at room temperature for 16 hours, filtered through a 200 mesh wire mesh filter, and the insoluble matter is washed 3 times. Thus, the weight of the obtained residue (swelled body weight) was measured. Subsequently, the obtained residue was dried under reduced pressure at 80 ° C. for 1 hour at 1 Torr, and the weight after drying (dry body weight) was measured. From the weight of the swollen body and the weight of the dried body thus obtained, the expansion coefficient was determined by the following formula.
Expansion rate = (weight of swollen body / weight of dry body) × 100

[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 device (Rheometrics, RMS-800) at 170 ° C. and initial shear strain of 450%. The relaxation elastic modulus curve was drawn with time on the horizontal axis and the relaxation elastic modulus on the vertical axis, G (0.1) and G (T) were obtained, and the gradient K of the relaxation elastic modulus was calculated by the above equation (1).

[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 toners obtained in Examples 1 to 6 and Comparative Examples 1 to 3 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)]
An unfixed image was formed in the same manner as in the test for measuring the high temperature offset temperature and the low temperature offset temperature, the 100th image was fixed, and the image quality (presence of fogging) was confirmed visually. 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.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the resin composition for toners which is excellent in low temperature fixability and high temperature offset-proof property, a toner, and a toner resin composition can be provided.

It is a schematic diagram which shows an example of the extrusion kneader used for the manufacturing method of the resin composition for toners of this invention. 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.

Claims (10)

A method for producing a resin composition for a toner, wherein a crosslinked polyester and a low molecular weight linear polyester are uniformly mixed,
A step of injecting a branched polyester having a number average molecular weight of 2000 to 5000 and two or more isocyanate compounds in one molecule into an extrusion kneader to start a crosslinking reaction, and further before the crosslinking reaction is completed A method for producing a resin composition for a toner, comprising a step of charging and kneading a low molecular weight linear polyester. A method for producing a resin composition for a toner, wherein a crosslinked polyester and a low molecular weight linear polyester are uniformly mixed,
A cross-linking reaction is started by introducing a branched polyester having a number average molecular weight of 2000 to 5000, a linear polyester having a number average molecular weight of 2000 to 10,000, and two or more isocyanate compounds in one molecule into an extrusion kneader. And a method for producing a resin composition for a toner, comprising a step of adding and kneading a low molecular weight linear polyester before the crosslinking reaction is completed. A resin composition for toner containing a crosslinked polyester and a low molecular weight linear polyester,
The condition is that the swelling rate is 500 to 4000%, the flow softening point is 100 to 160 ° C., and 170 ° C. measured by a method of immersing in tetrahydrofuran, shaking at room temperature for 16 hours, and filtering with a 200 mesh wire mesh filter. When a shear strain of 450% is applied, a shear strain represented by the following formula (1) is applied, and the gradient K of the relaxation modulus curve from 0.02 seconds to 0.1 seconds is 5 to 26. A toner resin composition, comprising:

4. The resin composition for toner according to claim 3, wherein the crosslinked polyester is obtained by reacting a branched polyester having a number average molecular weight of 2000 to 5000 with two or more isocyanate compounds in one molecule. object. The crosslinked polyester is obtained by reacting a branched polyester having a number average molecular weight of 2000 to 5000, a linear polyester having a number average molecular weight of 2000 to 10,000, and two or more isocyanate compounds in one molecule. The toner resin composition according to claim 3. 6. The resin composition for toner according to claim 4, wherein the branched polyester having a number average molecular weight of 2000 to 5000 is obtained by reacting dicarboxylic acid, diol and tricarboxylic acid. 7. The resin composition for toner according to claim 3, wherein the branched polyester having a number average molecular weight of 2000 to 5000 has a hydroxyl value of 20 to 80. 8. The resin composition for a toner according to claim 3, 4, 5, 6, or 7, wherein the low molecular weight linear polyester has a number average molecular weight of 2000 to 5000. The resin composition for toner according to claim 3, 4, 5, 6, 7, or 8, wherein the low molecular weight linear polyester has an acid value of 20 to 80. A toner comprising the resin composition for toner according to claim 3, 4, 5, 6, 7, 8, or 9.

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