JP6766325B2 - Polyester resin for toner, its manufacturing method and toner - Google Patents

Description

The present invention relates to a polyester resin for toner, a method for producing the same, and a toner.

In the method of obtaining an image by the electrophotographic printing method and the electrostatic charge development method, the electrostatic charge image formed on the photoconductor is developed with a toner charged in advance by friction, and then fixing is performed. As the fixing method, there are a heat roller method in which the toner image obtained by development is fixed by using a pressurized and heated roller, and a non-contact fixing method in which the toner image is fixed by using an electric oven or flash beam light. In order to pass through these processes without problems, the toner must first retain a stable amount of charge and then must have good fixability on paper. Further, since the apparatus has a fixing portion which is a heating element and the temperature inside the apparatus rises, it is necessary that the toner does not block.

Further, it is necessary that no stains on the apparatus or fog on the printed surface are observed even during continuous printing, that is, the durability of the toner is required. Further, it is also required that the pulverizability is good in order to improve the productivity at the time of toner production. For this reason, polyester resin is used as a binder resin for toner, which has excellent durability and pulverizability.

As a method for improving the pulverizability, for example, it is known to use a resin having a crosslinked structure by using a polyfunctional monomer having a valence of 3 or more in a polyester resin. Further, as a method for improving durability, it is known to use a polyester resin having a crosslinked structure and a solvent-insoluble component. However, when a large amount of trivalent or higher polyfunctional monomer is used, the viscosity may increase remarkably and the resin may solidify in the polymerization apparatus.

For example, Patent Document 1 and Patent Document 2 describe a polyester resin for toner using a carboxylic acid component having a valence of 3 or more and an alcohol component having a valence of 3 or more.

Further, Patent Document 3 describes the pulverizability of a polyester resin for toner using a carboxylic acid component having a valence of 3 or more and an alcohol component having a valence of 3 or more.

Japanese Patent Application Laid-Open No. 2003-43741 JP-A-10-60100

However, the method of Patent Document 1 has a limitation in the polymerizable region depending on the amount of aromatic diol, which is insufficient from the viewpoint of polymerizability. The method of Patent Document 3 has insufficient durability because it does not have an insoluble matter in an organic solvent.

In order to achieve the above items, the present invention presents a polyester resin for toner containing a trivalent or higher carboxylic acid-derived component, a trivalent or higher alcohol-derived component, a divalent carboxylic acid-derived component, and a divalent alcohol-derived component. The divalent alcohol-derived component contains a divalent aromatic alcohol represented by the following general formula (1), and the number of moles of the total alcohol-derived component in the polyester resin / the molar number of the total carboxylic acid-derived component. number = the 1.10 to 2.50, 9-15 mole the trivalent or more carboxylic acid-derived component with respect to the total acid component monomer units 100 molar parts of the polyester resin, of the trihydric or higher The polyester resin contains 9 to 15 mol of an alcohol-derived component, and the polyester resin provides a polyester resin for toner having an insoluble content of 9% to 19% by weight with respect to THF.

The polyester resin of the present invention can provide a toner having excellent pulverizability and durability.

(Polyester resin for toner)
The polyester resin for toner of the present invention contains a trivalent or higher carboxylic acid-derived component, a trivalent or higher alcohol-derived component, a divalent carboxylic acid-derived component, and a divalent alcohol-derived component, and is a polyester resin for toner. The divalent alcohol-derived component contains a divalent aromatic alcohol represented by the following general formula (1), and the number of moles of the total alcohol-derived component / the number of moles of the total carboxylic acid-derived component in the polyester resin. = 1.10 to 2.50, and the polyester resin has an insoluble content of 6% by weight to 40% by weight with respect to THF.

By containing a trivalent or higher carboxylic acid and a trivalent or higher alcohol, the polyester resin for toner of the present invention forms a crosslinked structure in the resin and improves pulverizability and durability when used in toner. ..
Further, the polyester resin for toner of the present invention is excellent in production efficiency because the number of moles of the total alcohol component / the number of moles of the total carboxylic acid component = 1.10 to 2.50.
Further, the polyester resin for toner of the present invention has an insoluble content in the range of 6% by weight to 40% by weight with respect to THF, thereby exerting an action of imparting higher elasticity to the toner and improving the durability of the toner. Become good. The insoluble content in THF is preferably in the range of 7% by weight to 40% by weight, more preferably in the range of 8% by weight to 35% by weight.

(Carboxylic acid component of trivalent or higher)
Examples of the trivalent or higher carboxylic acid component used in the present invention include trimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalene tricarboxylic acid, and 1,2,4-naphthalene. Examples thereof include tricarboxylic acid, 1,2,5-cyclohexanetricarboxylic acid, 1,2,7,8-octatetracarboxylic acid and acid anhydrides thereof.

(Alcohol component of trivalent or higher)
Examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetralol, 1,4-sorbitan, pentaeristol, dipentaneeristol, trioleristol, 1,2,4- Butantriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4 butanetriol, trimethylolethan, trimethylpropane, 1,3,5-hydroxymethylbenzene And so on.
Trimellitic acid or an acid anhydride thereof is preferable as the trivalent or higher carboxylic acid component, and trimethylolpropane is preferable as the trihydric or higher alcohol.

The polyester resin used in the present invention contains 0.5 to 30 mol parts of a trivalent or higher carboxylic acid component with respect to 100 mol parts of the total acid component monomer unit in the resin. When this value is 0.5 mol parts or more, the pulverizability is improved. Further, the durability is improved by using 30 mol parts or less.

The polyester resin used in the present invention contains 0.5 to 30 mol parts of a trivalent or higher alcohol component with respect to 100 mol parts of the total acid component monomer unit in the resin. When this value is 0.5 mol parts or more, the pulverizability is improved. Further, the durability is improved by using 30 mol parts or less.

(Divalent carboxylic acid component)
Examples of the divalent carboxylic acid component include terephthalic acid, isophthalic acid or lower alkyl esters thereof, phthalic acid, sebacic acid, isodecylsuccinic acid, dodecenylsuccinic acid, maleic acid, fumaric acid, adipic acid, or monomethyl thereof. , Monoethyl, dimethyl, diethyl ester or components from their acid anhydrides. Examples of lower alkyl esters of terephthalic acid and isophthalic acid include dimethyl terephthalate, dimethyl isophthalate, diethyl terephthalate, diethyl isophthalate, dibutyl terephthalate, dibutyl isophthalate and the like, but in terms of workability and cost. From the viewpoint, terephthalic acid is preferable. Further, an aliphatic dicarboxylic acid component can also be used as appropriate.

(Divalent alcohol component)
The divalent alcohol component of the present invention includes an aromatic alcohol-derived component represented by the following formula (1).

(In the formula, R ₁ is an alkylene group having 3 or less carbon atoms, and m and n are natural numbers.)
Examples of the dihydric alcohol of the above formula (1) include polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene- (2.0) -2,2-. Bis (4-hydroxyphenyl) propane, polyoxypropylene (2.2) -polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2, 2-Bis (4-hydroxyphenyl) propane, polyoxypropylene (2.3) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-) Divalent aromatic alcohols such as hydroxyphenyl) propane can be mentioned, and these can be used alone or in combination of two or more.
Examples of the alcohols in Section 2 other than the above formula (1) include ethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, and 1,4-butanediol. Diethylene glycol, 2-methyl-1,3 propanediol, triethylene glycol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dotecandiol, etc. Divalent aliphatic alcohols can be mentioned, which can be used alone or in combination of two or more.

(Polyester resin manufacturing method)
In the method for producing a polyester resin of the present invention, the ratio of the number of moles of the total alcohol component / the total carboxylic acid component has a range of 1.10 to 2.50. If the ratio of the total number of moles of the total alcohol component / the total number of carboxylic acid components is less than 1.10, it is difficult to control the reaction because the resin may solidify in the polymerization apparatus due to a significant increase in viscosity in the reaction vessel. is there. Further, when the ratio of the number of moles of the total alcohol component / the total carboxylic acid component is 2.50 or less, the productivity in the polycondensation reaction tends to be good.

When the reaction is carried out using a polyfunctional monomer having a valence of 3 or more, it changes to a cross-linking component having a high cross-linking density (THF insoluble component) that does not dissolve in THF, and a part of the cross-linking component has a low cross-linking density that dissolves in THF. It changes to a cross-linking component. As a result, the resin obtained by the cross-linking reaction contains a THF-insoluble component (a polyester resin having a cross-linking component that is insoluble in THF) and a THF-soluble component (a polyester resin having a cross-linking component that dissolves in THF). It becomes. Since the THF-insoluble matter is crosslinked at a high density, it exerts an action of imparting higher elasticity to the toner, and the durability of the toner is improved.

The content of the THF insoluble matter is preferably 6% by mass or more in the polyester resin. When the THF insoluble content is 6% by mass or more, the durability of the toner tends to be good. The lower limit of the content of THF insoluble matter is particularly preferably 10% by mass or more. The upper limit of the content of the insoluble THF is preferably 40% by mass or less. When the THF insoluble content is 35% by mass or less, the pulverizability of the toner tends to be good. The upper limit of the content of THF insoluble matter is particularly preferably 35% by mass or less.

The acid component other than the trivalent or higher carboxylic acid component constituting the polyester resin of the present invention is not particularly limited, but the aromatic dicarboxylic acid component monomer unit is added to 100 mol parts of the total acid component monomer unit. It is preferably contained in an amount of 70 mol parts or more. When it is contained in an amount of 70 mol parts or more, it is preferable from the viewpoint of toner durability.
Further, the alcohol component constituting the polyester resin of the present invention is preferably contained in an amount of 110 to 250 mol parts with respect to 100 mol parts of the total acid component monomer unit. When the amount is 110 mol parts or more, the increase in the remarkable viscosity in the polycondensation reaction can be suppressed, which is preferable. Further, it is preferable that the amount is 250 mol parts or less because the productivity in the polycondensation reaction can be improved.

As for the method for producing the polyester resin of the present invention, a known method can be used. For example, the above-mentioned carboxylic acid component and alcohol component are charged together and polymerized through an esterification reaction, a transesterification reaction, and a polycondensation reaction to produce a polyester resin. In the polymerization of the polyester resin, for example, a polymerization catalyst such as titanium tetrabutoxide, dibutytin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, and diacid germanium can be used. The polymerization temperature is not particularly limited, but is preferably in the range of 180 to 290 ° C.

Further, a monovalent carboxylic acid component or a monohydric alcohol component can be used for the purpose of adjusting the number of terminalizable groups and improving the dispersibility of other toner materials as long as the object of the present invention is not impaired. Examples of the monovalent carboxylic acid component include aromatic carboxylic acids having 30 or less carbon atoms such as benzoic acid and p-methylbenzoic acid, aliphatic carboxylic acids having 30 or less carbon atoms such as stearic acid and behenic acid, and cinnamic acid. Examples thereof include unsaturated carboxylic acids having one or more unsaturated double bonds in the molecule, such as oleic acid, linoleic acid, and linolenic acid.

The polyester resin for toner of the present invention is preferably amorphous in consideration of its performance as a binder resin. Therefore, it is important to appropriately adjust the types and ratios of each raw material component.
Hereinafter, the polyester resin for toner obtained by the production method of the present invention will be described.
The softening temperature of the polyester resin for toner of the present invention is preferably 120 ° C. or higher. Further, when the softening temperature is 120 ° C. or higher, the non-offset property of the toner tends to be good. The softening temperature is preferably 170 ° C. or lower. This is because the fixability of the toner tends to be good.

The glass transition temperature (hereinafter referred to as Tg) of the polyester resin for toner of the present invention is not particularly limited, but is preferably 50 to 65 ° C. When the Tg is 50 ° C. or higher, the blocking resistance of the toner tends to be good, and when the Tg is 65 ° C. or lower, the fixing property of the toner tends to be good.

Further, the acid value of the polyester resin for toner of the present invention is not particularly limited, but is preferably 25 mgKOH / g or less. When the acid value is 25 mgKOH / g or less, the image density of the toner tends to be stable. The upper limit of the acid value of the polyester resin is more preferably 20 mgKOH / g or less, and particularly preferably 17 mgKOH / g or less.

(toner)
Next, a toner using the polyester resin for toner of the present invention will be described.

The polyester resin for toner of the present invention is suitable for a method for producing pulverized toner.

Further, the polyester resin for toner of the present invention can be used as a main component of a toner binder and as a component for improving the dispersibility and glossiness of a release agent by blending with other toner binder resins. .. Examples of the binder resin include polyester resins other than the polyester resin of the present invention, styrene resin, styrene-acrylic resin, cyclic olefin resin, methacrylic acid resin, epoxy resin, etc., as long as the effects of the present invention are not impaired. It can be used alone or in combination of two or more. It is preferable to add 5% by mass or more of the polyester resin of the present invention to the total amount of the binder resin.

Colorants for toner conversion include carbon black, niglocin, aniline blue, phthalocyanine blue, phthalocyanine green, hanza yellow, rhodamine-based pigments, chrome yellow, quinacridone, benzidine yellow, rose bengal, and triallylmethane dyes. Examples thereof include monoazo-based, disazo-based, condensed azo-based dyes and pigments. In the case of full-color toners, which can be used alone or in combination of two or more of these dyes and pigments, benzine yellow, monoazo dyes, condensed azo dyes, etc. as yellow, quinacridone, rhodamine as magenta, etc. Examples of cyan include phthalocyanine blue and the like, such as dyeing pigments and monoazo dyes.

The content of the colorant is preferably 2 to 10% by mass in the toner from the viewpoint of the color tone, image density, and thermal characteristics of the toner.

Examples of the charge control agent include a quaternary ammonium salt as a positive charge control agent, a basic or electron donating organic substance, and the like, and as a negative charge control agent, metal chelate, metal-containing dye, acidic or electron-withdrawing property. Examples include organic substances. In the case of color toners, it is important that the charge control agent is colorless or dyed and that there is no color disturbance to the toner, for example, metal salts of salicylic acid or alkylsalicylic acid such as chromium, zinc, aluminum, metal complexes, amide compounds. , Phenolic compounds, naphthol compounds and the like. Further, a styrene-based, acrylic acid-based, methacrylic acid-based, or vinyl polymer having a sulfonic acid group may be used as the charge control agent.

The content of the charge control agent is preferably 0.5 to 5% by mass in the toner. When the content of the charge control agent is 0.5% by mass or more, the charge amount of the toner tends to be a sufficient level, and when it is 5% by mass or less, the decrease in the charge amount due to the aggregation of the charge control agent is controlled. Tend to be.

Examples of the release agent added at the time of toner conversion include carnauba wax, rice wax, montan wax, beeswax, polypropylene wax, polyethylene wax, synthetic ester wax, paraffin wax, fatty acid amide, and silicone wax. it can.

The content of the mold release agent is preferably 0.3 to 5% by mass in the toner because it affects the mold release effect, storage stability, fixability, color development and the like of the toner. The lower limit of the content of the release agent is more preferably 1% by mass or more, and particularly preferably 2% by mass or more. The upper limit of the content of the release agent is more preferably 13% by mass or less, and particularly preferably 10% by mass or less.
Further, as additives such as a fluidity modifier, fluidity improvers such as fine powder silica, alumina and titania, inorganic fine powders such as magnetite, ferrite, cerium oxide, strontium titanate and conductive titania, and styrene resin. , Resistance modifiers such as acrylic resin, lubricants, etc., which are used as internal or external additives.

The content of these additives is not particularly limited, but is preferably 0.05 to 10% by mass in the toner. When the content of these additives is 0.05% by mass or more, the performance modifying effect of the toner tends to be sufficiently obtained, and when the content is 10% by mass or less, the image stability of the toner tends to be good. is there.

Examples of the present invention are shown below. Moreover, the evaluation method of the resin shown in this Example is as follows.

(1) Productivity The productivity with reaction time in the polycondensation reaction was evaluated according to the following criteria.
⊚: The desired torque was reached within the polymerization time of 1 hour.
〇: The desired torque was reached within a polymerization time of 2 hours or less.
Δ: The desired torque was reached within a polymerization time of 3 hours or less.
X: The desired torque was not reached even after the polymerization time of 3 hours or more.

(2) Glass transition temperature (Tg)
The temperature at the intersection of the baseline with the chart and the close battle of the endothermic curve near the glass transition temperature when measured at a temperature rise rate of 5 ° C / min using a differential scanning calorimeter DSC-60 manufactured by Shimadzu Corporation. Asked.

(3) Softening temperature (T4)
Using a flow tester CFT-500 manufactured by Shimadzu Corporation, measuring with a nozzle of 1 mmφ x 10 mm under a load of 294 N (30 kgf) and a temperature rise rate of 3 ° C./min at a constant rate of temperature rise, in 1.0 g of the sample. The temperature at which 1/2 of the amount flowed out was determined.

(4) Acid value About 0.2 g of the sample was precisely weighed in a flask with a branch (A (g)), 10 ml of benzyl alcohol was added, and the resin was dissolved by heating in a heater at 230 ° C. for 15 minutes under a nitrogen atmosphere. .. After cooling to room temperature, 10 ml of benzyl alcohol, 20 ml of chloroform, and several drops of phenolphthalein were added and titrated with a KOH solution of 0.02 (titration = B (ml), titer of KOH solution = p). The blank measurement was performed in the same manner (titration = C (ml)), and the calculation was performed according to the following formula.
Acid value (mgKOH / g) = (BC) x 0.02 x 56.11 x p ÷ A

(5) Gel fraction (THF insoluble content)
0.5 g of the resin was precisely weighed in a 100 ml Erlenmeyer flask (A (g)), 50 ml of THF was added, and the resin was dissolved in a water bath set at 70 ° C. for 3 hours. On the other hand, the glass filter 1GP100 was tightly filled with Celite 545 from 6 to 7 minutes, dried in a dryer at 105 ° C. for 3 hours or more, and weighed (B (g)). Subsequently, a THF solution in which the resin was dissolved was transferred into a dry glass filter and suction filtered. Using acetone, all the contents remaining on the wall of the Erlenmeyer flask were transferred into a glass filter, and acetone was poured through the glass filter to drop the soluble components into a suction bottle, and suction was continued so that no solvent remained in the filter. Later, it was dried in a vacuum dryer at 80 ° C. for 3 hours or more and weighed (C (g)).
Gel fraction (%) = (CB) / A × 100

(6) Durability The insoluble content in THF was evaluated in the range of 6% by weight to 40% by weight by the storage elastic modulus using a rotary rheometer (DAR-100 manufactured by REOLOGICA).
Measurement mode: Oscillation straight control
Geometry: 25mmφ parallel plate GAP: 1mm
Frequency: 1Hz
Straight: 0.01
Measurement temperature: 80-240 ° C (heated at 3 ° C / min)
The evaluation criteria were set as follows using the storage elastic modulus (G').
◎ (Very good): G'of 1000 mPa or more
○ (Good): G'of 100 mPa or more and less than 1000 mPa
Δ (Available): G'of 60 mPa or more and less than 100 mPa
× (inferior): G'less than 60 mPa

(7) Crushability The pulverizability was evaluated by determining the residual ratio of the resin remaining on the mesh. Here, the resin residual ratio is defined by sieving a resin that has undergone a normal pulverization step to obtain a resin powder that passes through 16 meshes and does not pass through 22 meshes, and 10.00 g of this classified resin powder is precisely weighed. After crushing for 10 seconds with a trio mesh blender crusher (manufactured by Trio Science), sieve through 30 mesh, weigh the mass (A) g of the resin that does not pass, and calculate the residual ratio from the value of A by the following formula. It is a value obtained by performing this operation three times and averaging it.
((A) g / resin weight before pulverization (10.00 g)) × 100 = resin residual ratio (%)
From the obtained resin residual ratio, the pulverizability was evaluated as follows.
◎ (Very good): Resin residual rate of less than 55% ○ (Good): Resin residual rate of 55% or more and less than 65% Δ (Available): Resin residual rate of 65% or more and less than 75% × (Inferior): Resin residual rate of 75% or more

(Example 1)
A titanium catalyst of 500 ppm with respect to the carboxylic acid, alcohol and total carboxylic acid having the charged composition shown in Table 1 was charged into a reaction vessel equipped with a distillation column. Next, the rotation speed of the stirring blade in the reaction vessel was kept at 200 rpm, the temperature was started, and the temperature in the reaction system was maintained by heating so as to reach 265 ° C. The temperature in the reaction system was lowered to 230 ° C., the pressure in the reaction vessel was reduced, and the polycondensation reaction was carried out while distilling the diol component from the reaction system. When the torque of the stirring blade showed a predetermined torque, the reactant was taken out and cooled to obtain resin 1. The characteristic values of the resin 1 are shown in Table 1.

(Examples 2 to 4, reference examples , comparative examples 1 and 2)
A polyester resin was obtained in the same manner as in Example 1 except that the composition charged in the reaction vessel was changed as shown in Table 1. Table 1 shows the characteristic values and evaluation results of the obtained resin.

Diol A: Polyoxypropylene- (2,3) -2,2-bis (4-hydroxyphenyl) Propane Diol Diol B: Polyoxyethylene- (2,0) -2,2-bis (4-hydroxyphenyl) Propanediol

From the above results, it was confirmed that the resin according to the present invention (Examples 1 to 4 ) is excellent in productivity, pulverizability and durability. On the other hand, when the gel fraction (insoluble in THF) was 0% (Comparative Example 1) or 5% (Comparative Example 2), it was confirmed that the productivity and durability were inferior.

Claims (3)

A polyester resin for toner containing a trivalent or higher carboxylic acid-derived component, a trivalent or higher alcohol-derived component, a divalent carboxylic acid-derived component, and a divalent alcohol-derived component, wherein the divalent alcohol-derived component is , The number of moles of the total alcohol-derived component / the number of moles of the total carboxylic acid-derived component in the polyester resin containing the divalent aromatic alcohol represented by the following general formula (1) = 1.10 to 2.50. The polyester resin contains 9 to 15 mol of the trivalent or higher carboxylic acid-derived component and 9 to 15 mol of the trivalent or higher alcohol-derived component with respect to 100 mol of the total acid component monomer unit. The polyester resin is a polyester resin for toner having an insoluble content of 9% to 19% by weight with respect to THF.
(In the formula, R ₁ is an alkylene group having 3 or less carbon atoms, and the sum of m and n is 2 to 6. ) A method for producing a polyester resin for toner by polycondensing a monomer mixture containing a trivalent or higher carboxylic acid, a trihydric or higher alcohol, a divalent carboxylic acid and a divalent alcohol, wherein the divalent alcohol is generally described below. The number of moles of the total alcohol component / the number of moles of the total carboxylic acid component in the monomer mixture containing the divalent aromatic alcohol represented by the formula (1) at the time of preparation is 1.10 to 2.50, and the polyester. The obtained polyester resin for toner contains 9 to 15 mol of the trivalent or higher carboxylic acid and 9 to 15 mol of the trivalent or higher alcohol with respect to 100 mol of the total acid component monomer unit in the resin. Is a method for producing a polyester resin for toner, which has an insoluble content of 9% by weight to 19% by weight with respect to THF.
(In the formula, R ₁ is an alkylene group having 3 or less carbon atoms, and the sum of m and n is 2 to 6. ) A toner containing the polyester resin for toner according to claim 1.