JP2002123040A - Resin composition for toner and toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the resin strength and anti-hot offsetting property of a resin for a toner having a low softening point expected to be used in a color toner, to provide a resin composition for a toner having high resin strength and a low softening point and excellent also in transparency and to provide a toner less liable to size reduction and ensuring little irregularity in the color tone when fixed. SOLUTION: A vinyl copolymer comprising a styrene monomer and a (meth) acrylic ester monomer as constitutional components is used as a base and an elastomer containing a styrene block as a constitutional unit is incorporated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition and a toner used as a toner resin for a toner used for developing an electrostatic image in electrophotography and the like, and more particularly, to a toner used in a dry development system. The present invention relates to a resin composition for toner and a toner.

[0002]

2. Description of the Related Art A dry developing method is frequently used as a method for developing an electrostatic image in electrophotography or the like. In the dry developing method, the toner charged by friction is attached to the electrostatic latent image on the photoreceptor by electric attraction to form a toner image, and after the toner image is transferred to paper, the toner is released from the toner. The sheet is fixed to a sheet by a heating roller having a surface configured to have a permanent visible image.

[0003] Among the printers of the dry development type, a printer using a non-magnetic one-component toner is a system that does not require toner replenishment and control of toner concentration. Therefore, the apparatus can be simplified and a recent color printer can be downsized. , And can respond to lower prices. However, the non-magnetic one-component toner does not contain a carrier component or a magnetic component that contributes to charging, and charges the toner only with a frictional force with a blade or a sleeve. The toner is larger than the system toner and is easily crushed during development.

In order to prevent the toner from being pulverized in the printer, a high resin strength is required for the non-magnetic one-component toner. Further, if the transparency of the toner resin is insufficient or the smoothness of the fixed toner surface is insufficient, light absorption or light scattering causes poor coloration of the toner. In particular, color toner is fixed on a plastic film such as OHP. In such a case, there is a problem that the desired color tone is not developed.

Japanese Patent Application Laid-Open No. 7-219269 discloses a resin for a toner comprising a vinyl copolymer containing a styrene monomer and a (meth) acrylate monomer as main components. Thereby, it is possible to achieve both easy melting on the low temperature side and offset resistance on the high temperature side, and it is possible to achieve sufficient resin strength. However, when assuming color toner applications, the toner surface to be fixed must be smooth, so the toner must be a resin using a low softening point toner resin, but if the softening point or viscosity of the resin decreases, the resin strength and There has been a problem that the offset property on the high temperature side is not sufficient.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a resin composition for a toner which solves the above-mentioned various disadvantages of the prior art, achieves both high resin strength and a low softening point, and has excellent transparency. It is an object of the present invention to provide a toner which is hardly fixed and has little color tone of the toner.

[0007]

Means for Solving the Problems The resin composition for a toner of the present invention comprises, as a main component, a vinyl copolymer having styrene monomer and (meth) acrylate monomer as constitutional units. And an elastomer containing a styrene block as a structural unit.

[0008] The vinyl copolymer used in the present invention comprises:
A styrene monomer and a (meth) acrylate monomer are used as constituent units. Examples of the styrene monomer include, in addition to styrene, o-methylstyrene, m-methylstyrene, p-chloromethylstyrene, p-chlorostyrene, p-hydroxymethylstyrene, 2- (p-vinylphenyl) ethanol , P-nitrostyrene, p-
(2-nitroethyl) styrene, p-cyanostyrene,
alkyl groups such as m-cyanostyrene, p-aminostyrene, 3,4-diaminostyrene, p-vinylbenzoic acid, and 3-vinylsalicylic acid, halogen groups, hydroxyl groups, nitro groups, cyano groups, amino groups, carboxyl groups, and the like And a styrene derivative having the formula:

The above (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic acid. Isobutyl,
N-octyl (meth) acrylate, dodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Lauryl (meth) acrylate, stearyl (meth) acrylate, chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylic acid 2
(Amino), (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate, and dialkyl esters of unsaturated dibasic acids such as dimethyl maleate, dimethyl fumarate and dimethyl itaconate. .

The vinyl copolymer may contain other vinyl monomers as constituent units in addition to the styrene monomer and the (meth) acrylic ester monomer. , Vinyl esters such as vinyl propionate, unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene, unsaturated diolefins such as butadiene and isoprene, halogenated ethylenes such as chloroethylene and fluoroethylene, (meth) Unsaturated carboxylic acids such as acrylic acid, α-ethylacrylic acid and crotonic acid; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, itaconic acid and citraconic acid; (meth) acrylonitriles such as (meth) acrylonitrile and chloroacrylonitrile; (Meth) acrylamide, dimethylacrylamide, N- Ji acrylamide, N chromatography (2
(Meth) acrylamides such as -hydroxyethyl) acrylamide; and vinyl monomers having a heterocyclic ring such as vinylpyrrolidone, 4-vinylpyridine and 4-vinyltetrahydrofuran.

The vinyl copolymer used in the resin composition for a toner of the present invention can achieve both low-temperature fixability and anti-offset property, so that a low molecular weight vinyl copolymer and a high molecular weight vinyl copolymer are used. It is preferable to use a polymer in combination, that is, to form at least two peaks derived from a low molecular weight polymer component and a high molecular weight polymer component in the molecular weight distribution curve.

In particular, considering transparency, a low molecular weight polymer having a weight average molecular weight of 3,000 to 50,000, a softening point (Tf) of 150 ° C. or less and a glass transition point (Tg) of 50 ° C. or more, and a weight average molecular weight 100,000-5,000,0
00, softening point (Tf) 150 ° C or higher, glass transition point (T
g) is preferably used in combination with a high molecular weight polymer having a temperature of 50 ° C. or higher. The proportion of the low molecular weight polymer is preferably 60 to 95% by weight of the vinyl copolymer.

The low molecular weight polymer has a weight average molecular weight of 50,
If it exceeds 3,000, the toner is easily crushed and becomes 3,000.
If it is less than 1, storage stability may decrease. Also,
If the softening point (Tf) exceeds 150 ° C., sufficient low-temperature fixability may not be obtained. In addition, the glass transition point (T
If g) is less than 50 ° C., the storage stability may decrease. Further, the weight average molecular weight of the high molecular weight polymer is 10
If it is less than 000, the offset resistance may decrease. The softening point (Tf) of the high molecular weight polymer is 15
If the temperature is lower than 0 ° C., the offset resistance may decrease. When the content of the low molecular weight polymer is less than 60% by weight, the toner is easily crushed and the low-temperature stability may be reduced. When the content is more than 95% by weight, the offset resistance may be reduced.

The elastomer containing a styrene block as a constituent unit used in the toner resin composition of the present invention is a copolymer comprising a hard block made of polystyrene and a soft block made of a rubber component. For example, polybutadiene, polyisoprene, vinyl polyisoprene and the like, and hydrogenated poly (ethylene-butylene), poly (ethylene-propylene) and the like can be mentioned.

Examples of the elastomer include a diblock having a structure of a hard block and a soft block, and a triblock having both ends of a hard block. The rubber properties of the soft block are exerted to increase the resin strength. For this purpose, it is preferable that the triblock copolymer be contained in an amount of 60% by weight or more.

Further, in order to achieve both a suitable rubber elasticity and compatibility with the vinyl copolymer, the polystyrene content should be less than 40.
It is preferably about 90%. If the polystyrene content is less than 40%, the compatibility with the vinyl copolymer may be reduced and transparency may be insufficient. If the polystyrene content is more than 90%, the rubber elasticity of the elastomer is reduced and high resin strength is obtained. May not be possible.

The weight average molecular weight of the elastomer is 1
It is preferably from 000 to 500,000, more preferably from 30,000 to 300,000. If it is less than 10,000, it is difficult to obtain a high resin strength, and if it exceeds 500,000, it becomes difficult to pulverize the resin, and the low-temperature fixability also decreases.

Specific examples of the elastomer include, for example, polystyrene-polybutadiene-polystyrene (SB
S), polystyrene-polyisoprene-polystyrene (SIS), polystyrene-poly (ethylene-butylene) -polystyrene (SEBS), polystyrene-poly (ethylene-propylene) -polystyrene (SEPS)
And so on. Among them, SEBS, SE
PS is particularly preferred.

The elastomer containing a styrene block as a constituent unit is used in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of a copolymer containing a styrene monomer and a (meth) acrylate monomer as a constituent unit. If the elastomer is less than 0.5 part by weight, insufficient resin strength or reduced offset resistance may occur if the elastomer is less than 0.5 part by weight. ,
When the low-temperature fixing property is reduced and the resin strength is too large, pulverization of the resin may be difficult.

The method of mixing the elastomer and the vinyl copolymer is not particularly limited. For example, a method of mixing by melt-kneading with a roll mill, a kneader, an extruder or the like,
Solution polymerization, suspension polymerization, emulsion polymerization, a process in which the vinyl copolymer is polymerized by bulk polymerization or the like, that is, before polymerization, during polymerization, a method of adding at any stage after polymerization, and the like, particularly, It is preferably added during the course of polymerization by solution polymerization.

In the resin composition for a toner of the present invention, a low-melting crystalline compound having a melting point of 55 to 130 ° C. is mixed with a copolymer of a styrene monomer and a (meth) acrylate monomer. Preferably. The melting point is 55 to 130
Examples of the crystalline compound having a low melting point at ° C. include crystalline compounds having a low molecular weight, waxes, crystalline polymers, and the like.

Examples of the low molecular weight crystalline compound include 1-hexadecanol, 1-heptadecanol, stearyl alcohol, 1-nonadecanol, 1-eicosanol, 1-docosanol, 1-tricosanol, 1-tetracosanol Higher alcohols such as knol and seryl alcohol; higher fatty acids such as palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, eicosanoic acid, behenic acid, tricosanoic acid, and lignoceric acid; and esters thereof; linoleic acid amide, ricinoleamide, and elca Fatty acid amides such as acid amide, oleic acid amide, eicosenoic acid amide, erucic acid amide, and palmitoleic acid amide; and n-paraffins having 21 or more carbon atoms.

Examples of the waxes include animal waxes such as beeswax and whale wax; vegetable waxes such as carnauba wax, candelilla wax and wood wax; petroleum waxes such as paraffin wax and microcrystalline wax; Synthetic hydrocarbons such as Tropsch wax, polyethylene wax, and polypropylene wax.

Examples of the crystalline polymer include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, hexamethylene glycol, and tetramethylene glycol. And polyols such as fumaric acid, maleic acid,
Polyesters obtained by polycondensation with polybasic acids such as itaconic acid, terephthalic acid, succinic acid, adipic acid and sebacic acid; polyethers such as polyethylene glycol and polypropylene glycol; behenyl acrylate, behenyl methacrylate, itacone Vinyl polymers containing a long-chain alkyl ester such as behenyl acid or stearyl itaconate as a main polymerized unit may be used.

Among the above-mentioned crystalline compounds having a low melting point, waxes are preferable. In order to satisfy both the low-temperature fixability and the offset resistance, the molecular weight and the dispersibility are limited. , Propylene wax and the like are preferably used.

The crystalline compounds having a low melting point may be used alone or in combination of two or more.

The low melting crystalline compound having a melting point of 55 to 130 ° C. is 0.5 to 20 parts by weight based on 100 parts by weight of a copolymer of a styrene monomer and a (meth) acrylate monomer.
It is preferable to mix them in an amount of less than 0.5 part by weight.
If the amount is more than 10 parts by weight, the storage stability may decrease.

The toner of the present invention is a toner using the above-described resin composition for a toner, and contains a coloring agent, a charge control agent, a release agent, magnetic fine particles, a fluidizing agent, etc. as necessary. is there.

Examples of the coloring agent include carbon black, chrome yellow, aniline blue, phthalocyanine blue, ultramarine blue, and nigrosine dye. Further, examples of the charge control agent include a rhodamine dye, an azo-based metal complex, and a nigrosine dye. Examples of the release agent include polypropylene, polyethylene, and ethylene-propylene copolymer.
Examples of the magnetic fine particles include metals such as nickel, manganese, iron, cobalt, and chromium, various ferrites, and various alloys.

Examples of the fluidizing agent include hydrophobic silica powder, acrylic resin powder, fluorine resin powder, and metal salt powder of higher fatty acid.

(Function) The resin composition for a toner of the present invention comprises a vinyl-based copolymer having styrene-based monomer and (meth) acrylate-based monomer as constituent units, and a styrene block. Since it contains an elastomer as a unit, the compatibility between the styrene monomer part constituting the vinyl copolymer and the styrene block part constituting the elastomer is improved by mutual compatibility, and the toner becomes transparent. The performance is improved. Further, since an elastomer compatible with the vinyl copolymer is contained, rubber elasticity is imparted and resin strength is improved.

[0032]

EXAMPLE 1 600 g of toluene was placed in a 3-liter separable flask, and 100 g of a styrene-n-butyl acrylate-methyl methacrylate copolymer having a weight average molecular weight of 1.2 million and a styrene-ethylene propylene-styrene elastomer (weight). 50 g of an average molecular weight of 50,000, a styrene content of 65% by weight, and a triblock polymer) were added, the system was purged with nitrogen gas, and then heated to the reflux temperature of toluene. Then, while stirring at the reflux temperature of toluene, 800 g of a styrene monomer, 50 g of a methyl methacrylate monomer, and 15 g of an n-butyl acrylate monomer
0 g, azobisisobutyronitrile (polymerization initiator) 40
The mixture in which g was dissolved was dropped over 2.5 hours to perform solution polymerization.

After completion of the dropwise addition, the mixture was further stirred at the reflux temperature of toluene and aged for 30 minutes.
The solvent was removed under reduced pressure while the temperature was raised to 60 ° C. to obtain a resin composition. After cooling, the obtained resin composition was pulverized to obtain a resin composition for toner.

To 100 parts by weight of the resin composition for toner,
8 parts by weight of carbon black, 1 part by weight of a charge control agent and 3 parts by weight of a polypropylene wax are melt-kneaded, cooled, roughly pulverized, and further finely pulverized by a jet mill (Nippon Pneumatic Industrial Co., Ltd. "Labjet"). , Average particle size 8 ~
The toner powder having an average particle diameter of 12 μm was classified by a classifier (“MDS-2” manufactured by Nippon Pneumatic Industries, Ltd.) to obtain particles having an average particle diameter of 10 μm. To 300 g of the particles, 3 g of hydrophobic silica powder finely pulverized with a coffee mill was added and mixed with a mixer to obtain a toner.

Example 2 Instead of a styrene-ethylene propylene-styrene elastomer (weight average molecular weight: 50,000, styrene content: 65% by weight, triblock polymer), a styrene-ethylene propylene-styrene elastomer (weight average molecular weight: 60,000) , Styrene content 15% by weight,
(Triblock polymer / diblock polymer = 60/40)
Except that the average particle diameter was 10 in the same manner as in Example 1.
A μm toner was obtained.

Example 3 Instead of styrene-ethylene propylene-styrene elastomer (weight average molecular weight: 50,000, styrene content: 65% by weight, triblock polymer), styrene-ethylene propylene-styrene elastomer (weight average molecular weight: 60,000) , Styrene content 15% by weight,
(Triblock polymer / diblock polymer = 40/60)
Except that the average particle diameter was 10 in the same manner as in Example 1.
A μm toner was obtained.

Example 4 Instead of a styrene-ethylene propylene-styrene elastomer (weight average molecular weight: 50,000, styrene content: 65% by weight, triblock polymer), a styrene-ethylene propylene-styrene elastomer (weight average molecular weight: 60,000) , Styrene content 30% by weight,
A toner having an average particle size of 10 μm was obtained in the same manner as in Example 1 except that triblock polymer) was used.

Example 5 250 parts of a styrene-ethylene propylene-styrene elastomer (weight average molecular weight: 50,000, styrene content: 65% by weight, triblock polymer)
g, and a toner having an average particle diameter of 10 μm was obtained in the same manner as in Example 1.

Comparative Example The average particle size was the same as in Example 1 except that a styrene-ethylene propylene-styrene elastomer (weight average molecular weight: 50,000, styrene content: 65% by weight, triblock polymer) was not used. 10 μm
Was obtained.

(Evaluation) The following resin compositions or toners obtained in Examples 1 to 5 and Comparative Example were subjected to measurement and performance evaluation of the following items, and the results are shown in Tables 1 and 2. (1) Measurement of glass transition point (Tg) After measuring using a DSC220C (manufactured by Seiko Denshi Kogyo Co., Ltd.) at a heating rate of 10 ° C./min to obtain a suggestive heat curve, the intersection of the tangents was determined as the glass transition point. (Tg).

(2) Measurement of softening point (Tf) Flow tester “CFT-500A” manufactured by Shimadzu Corporation
Nozzle diameter 1 mm, thickness 0.1 mm, load 20
The measurement was performed at a heating rate of 6 ° C./min and a preheating time of 300 seconds in a measurement temperature range of 60 to 200 ° C. under the measurement conditions of kgf. After obtaining the flow curve by measurement, the plunger descent amount (outflow amount)
The temperature corresponding to the middle point was defined as the softening point (Tf).

(3) Measurement of Molecular Weight From the molecular weight distribution curve of the resin composition for a toner obtained by gel permeation chromatography (GPC), the molecular weight of two peaks is drawn from the base line perpendicular to the peak valley. The weight average molecular weight of each of the parts was calculated. A GPC device (“HTR-C” manufactured by Nippon Millipore Limited) was used for the measurement, and the column “K” manufactured by Showa Denko KK was used.
F-800P ”, 2“ KF-806M ”,“ KF
-802.5 "was used.
The measurement temperature was 40 ° C. and a 0.2% by weight THF solution (0.4%) was used.
100 μl) which had passed through a 5 μm filter. In addition, standard polystyrene was used as a calibration sample.

(4) Evaluation of Transparency 0.2 g of the resin composition for toner was added to a float glass (100
× 100 × 2.5 (mm)) and placed on top of another float glass with a 36 μm-thick PET film interposed as a spacer, and the softening point (T
Pressing was performed for 30 minutes at the same temperature as in f) to prepare a test piece in which the thinned toner resin composition was sandwiched. Using a spectrophotometer (manufactured by Hitachi, Ltd., U-4000), the obtained test piece was used as the light sources A and C, the visual field was 2 °, and the measurement wavelength was 380 to 380.
The measurement was performed at a scan speed of 300 nm / min between 780 nm. The Y value of the light source A obtained here was defined as the transmittance.

(5) Evaluation of Resin Strength The resin composition for toner was roughly pulverized with a coffee mill and
After sieving with a combination of 22/30 mesh (JISZ8801) sieves for a certain period of time, 5 g of the resin remaining on the 22 mesh sieve was sampled. Resin 5
g was ground in a coffee mill for 10 seconds, and the ground material was sieved for 10 seconds using an “Powder Tester PT-E type” manufactured by Hosokawa Micron Corporation to measure the amount of resin remaining above 100 mesh (JISZ8801). The grinding ratio was calculated using the following equation. Pulverization rate = (pulverized material−residual resin amount / pulverized material) × 100 (%)

(6) Evaluation of Storage Stability 20 g of the toner was placed in a 200 ml sample bottle and placed at 50 ° C.
After being left for 48 hours in a constant temperature bath, the amplitude was adjusted to 1 using a “Powder Tester PT-E” manufactured by Hosokawa Micron Corporation.
mm, and passed through a sieve for 10 seconds, and the resin remaining on the 250-mesh sieve was 1 g or less, which was regarded as acceptable.

(7) Evaluation of Durability A color printer (manufactured by Canon Inc., trade name “LBP-2”)
040 ") under standard conditions after passing 3,000 sheets, and it was checked whether toner was fused on the charging blade, the developing roller and the photosensitive drum. (8) Evaluation of presence / absence of image deterioration 3,000 sheets were passed under the standard conditions of a color printer, and it was confirmed whether there was a decrease in image density, occurrence of fog, and no back stain.

[0047]

[Table 1]

[0048]

[Table 2]

The evaluation results of Examples 1 to 5 in Table 2 show that the resin composition for a toner containing an elastomer has a low pulverization rate and improves the durability and image deterioration of the toner.
The evaluation results of Examples 1 and 5 show that the higher the styrene content of the elastomer, the higher the transparency of the resin composition for toner. Further, from the evaluation results of Example 5, in the resin composition for toner containing a large amount of elastomer, the pulverization rate was suppressed to be low, and the durability and image deterioration of the toner were improved.

[0050]

The resin composition for toner according to the present invention can achieve both high resin strength and low softening point, and the resulting toner is hard to be pulverized, has excellent transparency, and has little color tone of the fixed toner. .

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Claims (6)

[Claims] Claims: 1. An elastomer comprising, as a main component, a vinyl copolymer having a styrene monomer and a (meth) acrylate monomer as constituent components, and an styrene block as a constituent unit. A resin composition for a toner, comprising: 2. The elastomer according to claim 1, wherein the elastomer containing a styrene block as a constituent unit is an elastomer containing 60% by weight or more of a triblock copolymer having a styrene block and a rubber component as a constituent unit. Resin composition for toner. 3. The resin composition for a toner according to claim 1, wherein the styrene content of the elastomer containing a styrene block as a constituent unit is 40 to 90% by weight. 4. An elastomer containing a styrene block as a constitutional unit in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of a copolymer of a styrene monomer and a (meth) acrylate monomer. What is claimed is: 1. A resin composition for a toner, comprising: 5. A low-melting crystalline compound having a melting point of 55 to 130 ° C. based on 100 parts by weight of a copolymer of a styrene monomer and a (meth) acrylic ester monomer. 2
5. The composition according to claim 1, wherein 0 part by weight is blended.
3. The resin composition for toner according to item 1. 6. A toner using the resin composition for a toner according to claim 1.