JP4173779B2 - Binder resin for toner - Google Patents

Description

  The present invention relates to a binder resin for toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and a toner containing the binder resin.

With the recent miniaturization and speeding up of machines, the stress on the toner increases and it becomes more susceptible to the environment. In addition to fixability, it is represented by prevention of embedding of external additives and charging stability. Higher durability is required. From this point of view, a toner is known that contains, as a binder resin, an alkylene oxide adduct of bisphenol A and a linear or low-crosslinked polycondensate of an aromatic carboxylic acid containing approximately equimolar amounts of isophthalic acid and terephthalic acid. However (see Patent Documents 1 to 3), fixability and durability are difficult to achieve, and further improvements are desired.
JP 2001-215755 A (Claims 3 and 4) JP 2001-265063 A (Claim 1, [0058] etc.) JP 2002-6555 A (Claims 4, 5 etc.)

  An object of the present invention is to provide a toner binder resin excellent in both fixing property and durability and a toner containing the binder resin.

  The present invention relates to an alcohol component containing 50 mol% or more of an ethylene oxide adduct of bisphenol A in a total alcohol component, terephthalic acid in an amount of 80 mol% or more in a divalent carboxylic acid component, and 70 mol in all carboxylic acid components. %, A polyester obtained by polycondensation with a carboxylic acid component contained in an amount of at least%, a binder resin for toner comprising a polyester having a softening point of 130 ° C. or more, and a toner comprising the binder resin About.

  By using the binder resin for toner of the present invention, it is possible to obtain a toner excellent in both fixability and durability, which are characteristics that are difficult to be compatible with each other.

  The binder resin for toner of the present invention contains a polyester obtained by condensation polymerization of a specific alcohol component and a specific carboxylic acid component.

  As the alcohol component, an alcohol component containing 50 mol% or more, preferably 70 mol% or more, more preferably 100 mol% of the bisphenol A ethylene oxide adduct is used. Since the ethylene oxide adduct of bisphenol A has high reactivity and the high molecular weight of the resin can be achieved without significantly increasing the softening point, durability due to stress resistance and the like can be improved. Further, since the ethylene oxide adduct of bisphenol A is a monomer having a large molecular weight, the ester group concentration can be lowered, the amount of terminal functional groups is also reduced, and the environmental resistance is improved.

  From the viewpoint of durability, the number average added mole number of ethylene oxide with respect to bisphenol A is preferably 2.0 to 2.5, and more preferably 2.0 to 2.3.

  Preferred examples of the ethylene oxide adduct of bisphenol A include polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4 -Hydroxyphenyl) propane and the like.

  Examples of dihydric alcohol components other than bisphenol A ethylene oxide adducts include propylene oxide adducts of bisphenol A such as polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (number average) Additional mole number 2-5), ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, hydrogenated bisphenol A and the like.

  Examples of the trihydric or higher polyhydric alcohol component include sorbitol, pentaerythritol, glycerin, trimethylolpropane and the like.

  On the other hand, as the carboxylic acid component, a carboxylic acid component containing a specific amount of terephthalic acid is used. The content of terephthalic acid is 80 mol% or more in the divalent carboxylic acid component, preferably 90 mol% or more, more preferably 95 to 100 mol%, and 70 mol% in the total carboxylic acid component. It is above, Preferably it is 80-95 mol%. By using terephthalic acid having a rigid skeleton as a monomer component, it is resistant to mechanical stress, and is also thermally resistant to external additives and machine contamination due to heat generated by mechanical stress and heat in the machine. Excellent resin can be obtained.

  In addition, divalent carboxylic acid components other than terephthalic acid include aromatic dicarboxylic acids such as phthalic acid and isophthalic acid; oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, and succinic acid. , Aliphatic dicarboxylic acids such as succinic acid substituted with alkyl groups having 1 to 20 carbon atoms or alkenyl groups having 2 to 20 carbon atoms such as adipic acid, dodecenyl succinic acid and octyl succinic acid; anhydrides of these acids and the like And alkyl (1 to 3 carbon atoms) esters of these acids.

  Examples of the trivalent or higher polyvalent carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid and acid anhydrides thereof, and lower alkyl. (C1-C3) ester etc. are mentioned.

  In the polyester of the present invention, a trivalent or higher monomer is preferably used as a raw material monomer from the viewpoint of durability. From the viewpoint of durability, the content of the trivalent or higher monomer, that is, the trivalent or higher polyhydric alcohol component and / or the polyvalent carboxylic acid component, is preferable in each component in any of the alcohol component and the carboxylic acid component. Is 5 to 30 mol%, more preferably 10 to 25 mol%, or in any component, preferably 5 to 30 mol%, more preferably 10 to 25 mol%. In particular, the content of the trivalent or higher polyvalent carboxylic acid component is preferably 5 to 30 mol%, more preferably 10 to 25 mol% in the carboxylic acid component.

  Furthermore, from the standpoint of molecular weight adjustment and the like, a monovalent alcohol component and a monovalent carboxylic acid component may be appropriately contained as long as the effects of the present invention are not impaired.

  Polyester is, for example, a raw material monomer composed of an alcohol component and a carboxylic acid component in an inert gas atmosphere, if necessary in the presence of an esterification catalyst, preferably at 150 to 280 ° C, more preferably at 200 to 230 ° C. Obtained by condensation polymerization. In addition, it is preferable to add a trivalent or higher monomer acting as a cross-linking agent when the reaction rate of the divalent monomer reaches 90% or more to cause a two-stage reaction.

  The softening point of the polyester is 130 ° C. or higher, preferably 135 to 160 ° C., more preferably 140 to 155 ° C., from the viewpoint of achieving both fixing properties and durability. The softening point of the polyester can be adjusted by, for example, the molecular weight. In order to increase the softening point, it is preferable to increase the molecular weight of the polyester. The increase in the molecular weight of the polyester includes the ratio of the alcohol component to the carboxylic acid component, the use of a trivalent or higher monomer, the reaction temperature, the adjustment of the reaction pressure, etc. This can be done by a known method.

  The acid value of the polyester is preferably 1 to 10 mgKOH / g, more preferably 3 to 7 mgKOH / g, from the viewpoint of environmental resistance. From the viewpoint of adjusting the acid value, the molar ratio of the alcohol component to the carboxylic acid component (carboxylic acid component / alcohol component) is preferably 1 to 0.6, more preferably 0.9 to 0.75.

The glass transition point of the polyester is preferably 55 to 80 ° C, more preferably 60 to 70 ° C, from the viewpoint of durability and fixability.

  The polyester obtained by using the specific alcohol component and carboxylic acid component is preferably contained in the binder resin for toner of the present invention in an amount of preferably 50% by weight or more, more preferably 60 to 90% by weight. . In addition to the polyester, the resin that may be contained in the binder resin of the present invention includes polyesters other than the polyester of the present invention, styrene-acrylic resins, mixed resins of polyester and styrene-acrylic resins, and two or more resins. Examples include hybrid resins having components, among which polyesters having a softening point of less than 130 ° C., preferably 90 to 120 ° C., having such softening points, and specific alcohol components and A polyester obtained using a carboxylic acid component is more preferred.

  Furthermore, the present invention provides a toner excellent in both fixability and durability, containing the binder resin of the present invention.

  For toner, colorants, charge control agents, release agents, conductivity modifiers, extender pigments, reinforcing fillers such as fibrous substances, antioxidants, anti-aging agents, fluidity improvers, improved cleaning properties An additive such as an agent may be appropriately contained.

  As the colorant, all of dyes and pigments used as toner colorants can be used, such as carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, Quinacridone, Carmine 6B, Disazo Yellow and the like can be used, and these can be used alone or in admixture of two or more. It can be used for both toner and full color toner. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  Charge control agents include nigrosine dyes, triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives and other positively chargeable charge control agents and metal-containing azo dyes, copper Examples include negatively chargeable charge control agents such as phthalocyanine dyes, metal complexes of alkyl derivatives of salicylic acid, and boron complexes of benzylic acid.

  Examples of mold release agents include natural ester waxes such as carnauba wax and rice wax, synthetic waxes such as polypropylene wax, polyethylene wax, and Fischer Tropu, coal waxes such as montan wax, and waxes such as alcohol waxes. These may be used alone or in admixture of two or more.

  The toner of the present invention may be produced by any conventionally known method such as a kneading and pulverizing method, a phase inversion emulsification method, and a polymerization method. From the viewpoint of productivity, the pulverized toner by the kneading and pulverizing method is used. Preferably, the binder resin, colorant, charge control agent, release agent, etc. of the present invention are uniformly mixed with a mixer such as a Henschel mixer, and then a sealed kneader or a single or twin screw extruder, an open roll It can be produced by melt-kneading with a mold kneader or the like, cooling, pulverizing and classifying. The volume average particle diameter of the toner of the present invention is preferably 3 to 15 μm. Further, a fluidity improver such as hydrophobic silica may be externally added to the surface of the toner.

  When the toner of the present invention contains a magnetic fine powder, it is used alone as a developer, and when it does not contain a magnetic fine powder, it is used as a non-magnetic one-component developer or mixed with a carrier to develop a two-component developer. The agent is not particularly limited, and can be used in any developing method. However, it can be used for a non-magnetic one-component developing device that has a large mechanical stress due to the blade and requires charging stability. preferable.

  As a non-magnetic one-component developing device in which the toner of the present invention is suitably used, for example, a triboelectric charging is performed while uniformly regulating the thickness of a toner carrier such as a developing roll and a toner layer formed on the toner carrier. And a developing device having an electrostatic latent image carrier such as a photoconductor.

  Examples of the material of the developing roll include metals such as aluminum, iron, and stainless steel (SUS) that do not have an elastic layer, and the surface thereof may be processed by a processing method such as sandblasting. Examples of those having an elastic layer include natural rubber, nitrile rubber (NBR), silicone rubber, urethane rubber, butadiene rubber, chloroprene rubber, neoprene rubber, isoprene rubber, and the like. It may be in the form of foam, sponge or the like. In the present invention, the material of the developing roll is preferably NBR from the viewpoints of chargeability, stress resistance, and durability such as filming suppression of the polyester obtained using the specific alcohol component and carboxylic acid component.

[Softening point of resin]
Using a Koka type flow tester (manufactured by Shimadzu Corporation, CFT-500), a 1 g sample was heated at a heating rate of 6 ° C./min, a load of 1.96 MPa was applied by a plunger, a diameter of 1 mm, A nozzle with a length of 1 mm is pushed out, and this draws a plunger drop amount (flow value) -temperature curve of the flow tester. When the height of the S-shaped curve is h, the temperature corresponding to h / 2 (resin The temperature at which half of the effluent flowed out) is taken as the softening point.

[Glass transition point of resin]
Using a differential scanning calorimeter (DSC210, manufactured by Seiko Denshi Kogyo Co., Ltd.), the sample was heated to 200 ° C. and cooled to 0 ° C. at a temperature decreasing rate of 10 ° C./min. The temperature at the intersection of the base line extension below the maximum peak temperature and the tangent showing the maximum slope from the peak rising portion to the peak apex is defined as the glass transition point.

[Acid value of the resin]
The acid value was measured according to the method of JIS K0070.

Examples 1-3 and Comparative Examples 1-5
(1) Production of resin Raw materials other than trimellitic anhydride shown in Tables 1 and 2 and 4 g of dibutyltin oxide were added to a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple. Then, after reacting at 230 ° C. for 8 hours and at 8.3 kPa for 1 hour, trimellitic anhydride is reacted at 210 ° C. for 1 hour at normal pressure and then at 200 kPa until the desired softening point is reached. Resins A to H were obtained. Tables 1 and 2 show the softening point, glass transition point, and acid value of the obtained resin.

(2) Manufacture of toner The amount (parts by weight) of resin used in Table 3 as a binder resin, 4 parts by weight of carbon black “MOGUL L” (Cabot), charge control agent “T-77” (Hodogaya Chemical) Kogyo Co., Ltd.) 0.5 parts by weight, polypropylene wax “NP-055” (Mitsui Chemicals Co., Ltd.) 1 part by weight and Fischer-Tropsch wax “SP-105” (Sazol Co., Ltd.) are thoroughly mixed with a Henschel mixer, and then rolled. The mixture is melt kneaded using a co-rotating twin screw extruder with an internal heating temperature of 100 ° C., and the resulting mixture is cooled, coarsely pulverized, pulverized with a jet mill, classified, and a volume average particle size of 8.0 μm. Of powder was obtained.
To 100 parts by weight of the obtained powder, 1 part by weight of hydrophobic silica “Aerosil R-972” (manufactured by Nippon Aerosil Co., Ltd.) and 1.0% of hydrophobic silica “RY-50” (manufactured by Nippon Aerosil Co., Ltd.) as external additives A part by weight was added and mixed with a Henschel mixer to obtain a toner.

Test Example 1 [Evaluation of Fixability]
Toner is mounted on a non-magnetic one-component developing device “AR-505” (manufactured by Sharp Corporation) equipped with an NBR developing roll, and a solid image of 2 cm × 12 cm (toner adhesion amount: 0.5 mg / cm ^2). ) Was obtained in an unfixed state.
The obtained unfixed image was subjected to a fixing test while being gradually increased from 90 ° C. to 240 ° C. by 5 ° C. using an “AR-505” fixing device (fixing speed 100 mm / sec). . “CopyBond SF-70NA” (manufactured by Sharp Corporation, 75 g / m ² ) was used as the fixing paper.

  A load of 500 g was placed on a sand eraser having a bottom surface of 15 mm × 7.5 mm, and rubbed 5 times on the fixed solid image. The optical reflection density before and after rubbing is measured using a reflection densitometer “RD-915” (manufactured by Macbeth Co.), and the ratio of the two (after rubbing / before rubbing) first exceeds 70% at the lowest temperature of the fixing roller. The fixing property was evaluated according to the following evaluation criteria, with the fixing temperature. The results are shown in Table 3.

〔Evaluation criteria〕
A: Minimum fixing temperature is less than 170 ° C. O: Minimum fixing temperature is 170 ° C. or higher and lower than 180 ° C. ×: Minimum fixing temperature is 180 ° C. or higher.

Test Example 2 [Durability Evaluation]
A non-magnetic one-component developing device “ML-4300i” (manufactured by SAMUNG) equipped with an NBR developing roll is mounted with 70 g of toner, and an image with a printing rate of 5% under an environment of a temperature of 30 ° C. and a relative humidity of 65%. 2000 sheets were printed. After printing, an image obtained by continuously printing a solid image was visually observed, and durability was evaluated according to the following evaluation criteria. The results are shown in Table 3.

〔Evaluation criteria〕
A: A uniform solid image was obtained.
○: Slight fading appeared on the solid image.
Δ: Fading appeared in the solid image.
X: The solid image was blurred and white streaks appeared.

From the above results, it can be seen that the toners of the examples are excellent in both fixing ability and durability, which are generally difficult to achieve.
On the other hand, the toners of Comparative Examples 1 and 5 containing a polyester mainly composed of a propylene oxide adduct of bisphenol A and the toners of Comparative Examples 2 and 4 containing a polyester having a small amount of terephthalic acid are inferior in durability. Yes. Further, the polyester used in Comparative Example 3 is a polyester mainly composed of a propylene oxide adduct of bisphenol A, which has a high softening point (high molecular weight), but has reduced toner fixability. .

  The binder resin of the present invention is used as a binder resin for a toner used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method or the like.

Claims (5)

Alcohol component containing 70 mol% or more of ethylene oxide adduct of bisphenol A in all alcohol components, and terephthalic acid contained 80 mol% or more in divalent carboxylic acid components and 70 mol% or more in all carboxylic acid components. A polyester obtained by polycondensation with a carboxylic acid component, comprising a trivalent or higher monomer in an amount of 5 to 30 mol% in an alcohol component and / or 5 to 30 mol% in a carboxylic acid component, and a softening point Is a binder resin for toners containing polyester having a temperature of 135 ° C. or higher. Claim 1 Symbol placement of the binder resin acid value of the polyester is 1~10mgKOH / g. The binder resin according to claim 1 or 2 , wherein a molar ratio of the alcohol component to the carboxylic acid component (carboxylic acid component / alcohol component) is 0.9 to 0.6. Toner containing the claims 1-3 binder resin according to any one. A developing method using the toner according to claim 4 in a non-magnetic one-component developing device.