JPH07306546A - Resin for toner - Google Patents

Abstract

PURPOSE:To obtain a resin for a negative charge type toner excellent in fixability, anti-offsetting property, blocking resistance and image stability by using a copolymer obtd. by copolymerizing a mixture of specified monomers and having specified physical properties. CONSTITUTION:This resin for a toner is a copolymer obtd. by polymerizing a monomer mixture of arom. vinyl with (meth)acrylic acid, (meth)acrylic ester and a multifunctional compd. in the presence of a peroxide type polymn. initiator. The copolymer has 50-70 deg.C glass transition temp., 120-185 deg.C softening temp., 10-20mgKOH/g acid value, 15-50% gel fraction and the max. peak mol. wt. of <=10,000 in the mol. wt. distribution by gel permeation chromatography of a solvent-soluble polymer. Styrene is preferably used as the arom. vinyl and divinylbenzene, 1,3-butylene glycol dimethacrylate or ethylene glycol dimethacrylate is preferably used as the multifunctional compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin useful as a dry toner used in printers, copiers, facsimiles and the like in electrophotography, electrostatic printing, and more specifically, fixability, non-offset property, blocking resistance. sex,
The present invention relates to a negatively chargeable resin for toner having excellent image stability.

[0002]

2. Description of the Related Art Copiers, printers and the like have been improved in printing speed year by year, and accordingly, toner and binder resins have been improved year by year. For example, when charge is generated in the developing process, the toner and the carrier are rigorously agitated and mixed according to the printing speed, and the fixing temperature is being lowered in the fixing process. In other words, as the required performance, with respect to the toner and the resin for toner, as the fixing temperature becomes lower, the low-temperature fixing property is improved, the charging stability is improved to obtain a stable image, and the blocking resistance to prevent the toner from solidifying during storage. The sexuality has been improved.

In order to lower the fixing temperature and improve the fixing property, it is necessary to lower the molecular weight of the resin. However, in this case, there are problems that the non-offset property becomes poor as the molecular weight decreases, and that the glass transition temperature of the resin decreases as the molecular weight decreases and the blocking resistance becomes poor. Further, in the case of a styrene- (meth) acrylic acid ester-based resin, in order to reduce the molecular weight, it is necessary to increase the polymerization temperature or use a large amount of a polymerization initiator in the manufacturing process. Therefore, in recent years, a method has been adopted in which a large amount of a peroxide-based polymerization initiator is used at a high polymerization temperature to obtain a resin having a target molecular weight and fixability. However, when the resin obtained by this method is used for a negatively chargeable toner, the charge stability is poor due to the peroxide polymerization initiator used in a large amount, and the target charge amount is obtained. There are problems such as the absence. Conventionally, a method of treating a by-product based on the use of a peroxide-based initiator has been adopted for this problem, but the treatment is limited and a sufficient image cannot be obtained. Therefore,
There is a strong demand for the appearance of a negatively chargeable resin for toner that solves the above problems.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and its object is fixing property, non-offset property, blocking resistance and image stability. Another object of the present invention is to provide a resin for toner having excellent negative chargeability.

[0005]

Means for Solving the Problems The present invention has been obtained by intensively studying to achieve the above object, and was obtained by polymerizing a monomer mixture consisting of specific monomers with a peroxide type polymerization initiator. The inventors have found that a copolymer having specific physical properties can achieve the object, and completed the present invention. That is, the present invention is
(A) aromatic vinyl, (b) (meth) acrylic acid,
A copolymer obtained by polymerizing a monomer mixture comprising (c) a (meth) acrylic acid ester and (d) a polyfunctional compound in the presence of a peroxide-based polymerization initiator, which has a glass transition temperature. Is 50 to 70 ° C, and the softening temperature is 120 to 185.
C, acid value 10-20mgKOH / g, gel fraction 15
The resin for toner is characterized in that the maximum peak molecular weight in the molecular weight distribution of the solvent-soluble polymer by gel permeation chromatography is 10,000 or less.

The present invention will be described in detail below. The toner resin of the present invention comprises (a) aromatic vinyl, (b) (meth)
It is a copolymer composed of acrylic acid, (c) (meth) acrylic acid ester, and (d) polyfunctional monomer.

Examples of the aromatic vinyl (a) used in the present invention include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene and p-chlorostyrene. , 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, p. Examples thereof include -n-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene and α-methylstyrene, with styrene being particularly preferred. These aromatic vinyls may be used alone or in combination of two or more.

Also used in the present invention (meta)
Acrylic acid (b) is acrylic acid or methacrylic acid. The use of methacrylic acid is particularly preferred.

Also used in the present invention (meta)
Examples of the acrylic ester (c) include (meth)
Methyl acrylate (meaning methyl acrylate or methyl methacrylate, the same applies hereinafter), ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, propyl (meth) acrylate, ( Meta)
2-ethylhexyl acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, Examples thereof include glycidyl methacrylate, cyclohexyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, and the like, with methyl methacrylate and n-butyl (meth) acrylate being particularly preferable. These (meth) acrylic acid esters are used alone or in combination of two or more.

The polyfunctional compound (d) used in the present invention is a component that crosslinks the resin obtained,
It is a compound having two or more ethylenically unsaturated groups in one molecule. Examples thereof include aromatic divinyl such as divinylbenzene and divinylnaphthalene, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, di (meth) acrylic. Acid polyethylene glycol, di (meth) acrylic acid dipropylene glycol, di (meth) acrylic acid 1,3-butylene glycol, bisphenol A derivative di (meth) acrylic acid, and the like, but divinylbenzene, dimethacrylic acid 1 , 3-butylene glycol and ethylene glycol dimethacrylate are particularly preferred. These polyfunctional compounds are 1
They may be used alone or in combination of two or more.

The amounts of the aromatic vinyl (a), (meth) acrylic acid (b) and (meth) acrylic acid ester (c) used are such that the glass transition temperature of the resulting resin is 50 to 70.
It is not particularly limited as long as it is contained at a temperature of
Aromatic vinyl (a) is 50% by weight or more, preferably 52% by weight in the monomers consisting of the components (a) to (c).
It is necessary to use the above amount. This is because when the amount of the aromatic vinyl (a) used is less than 50% by weight, the moisture resistance of the toner is lowered. Also,
The amount of (meth) acrylic acid (b) used is from the above (a) to
1.5 to 3.1% by weight in the monomer comprising the component (c),
It is particularly preferably in the range of 1.7 to 2.9% by weight.
The (meth) acrylic acid (b) has the effect of adjusting the acid value of the resin, and further imparting the target charge amount and image stability of the toner. Therefore, when the amount of (meth) acrylic acid used is less than 1.5% by weight, it is difficult for the toner to obtain a stable image. On the other hand, when the amount used exceeds 3.1% by weight, the toner charge amount becomes large. The image density tends to be higher, and the image density tends to be lower than the target. The polyfunctional compound (d) is used in such an amount that the gel fraction of the resin is in the range of 15 to 50%, but is preferably based on the total amount of the components (a) to (c). 0.5 to 5% by weight, more preferably 0.55 to 4.5% by weight. If it is less than 0.5% by weight, the gel fraction of the resin tends to be low, and the non-offset property as a toner tends to be deteriorated. If it exceeds 5% by weight, the gel fraction of the resin tends to be high and the fixability as a toner is improved. This is because the value tends to decrease.

The toner resin of the present invention is preferably produced by a suspension polymerization method. As a method for producing the resin for toner, there can be mentioned a polymerization method such as a solution polymerization method, an emulsion polymerization method, and a bulk polymerization method in addition to the suspension polymerization. The solvent gives off an odor, and the image stability is poor, and in the emulsion polymerization method, a large amount of the emulsifier remaining in the obtained resin lowers the moisture resistance, and in the bulk polymerization method, it is difficult to control the heat of polymerization. It has drawbacks that it is not industrial, and it is difficult to manufacture the resin for toner which is the object of the present invention.

When the resin for toner of the present invention is produced by suspension polymerization, the above-mentioned polymerization components (a) to (d), a polymerization initiator, an emulsifier, an emulsification aid and deionized water are charged into a reaction vessel. Is polymerized with.

As the polymerization initiator used in the suspension polymerization, a peroxide type polymerization initiator is used. The peroxide polymerization initiator used has a 10-hour half-life of 6
Those in the range of 0 to 110 ° C. are preferably used.
As an example, for example, lauryl peroxide (62
℃), (the temperature in () indicates the temperature of 10-hour half-life. The same applies hereinafter.), Kumerperoxy octoate (6
8 ° C.), benzoyl peroxide (74 ° C.), t-butyl peroxy (2-ethylhexanoate) (72.
5 ° C.), m-toluoyl peroxide (73 ° C.), t
-Butyl peroxyisobutyrate (78 ° C), 1,1
-Bis (t-butylperoxy) 3,3,5-trimethylcyclohexane (90 ° C), t-butylperoxylaurate (96 ° C), cyclohexanone peroxide (97 ° C), t-butylperoxyisopropyl carbonate ( 98 ° C), t-butylperoxyacetate (102 ° C), t-butylperoxybenzoate (1
04 ° C.), di-t-butylperoxyisophthalate (107 ° C.), etc., but lauryl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate are preferably used. To be done. These polymerization initiators may be used either individually or in combination of two or more. In the present invention, the combined use of two types of polymerization initiators having different half-life temperatures reduces residual monomers and results in It is particularly preferable because it brings about the effect of increasing the glass transition temperature.

The amount of the polymerization initiator used is not particularly limited, but is in the range of 3.5 to 10 parts by weight with respect to 100 parts by weight of the above-mentioned polymerization components (a) to (d).

The dispersant used in suspension polymerization is a dispersant used in ordinary suspension polymerization, and for example, polyvinyl alcohol, sodium polyacrylate dispersant, polyether dispersant or the like is used. You can The dispersion aid used in suspension polymerization may be a dispersion aid used in ordinary suspension polymerization, for example, sodium sulfate, sodium carbonate, calcium carbonate, manganese sulfate,
Hydrogen peroxide water, boric acid or the like can be used.

Further, the polymerization components (a) to
The amount of deionized water used relative to (d) was 1.
It is in the range of 5 to 2.5, preferably 1.8 to 2.3.

The reaction temperature in suspension polymerization is 10 under pressure.
It is 0 ° C or higher, preferably 110 ° C to 150 ° C. 10
If it is less than 0 ° C, it becomes difficult to reduce the molecular weight of the resin.

Further, in suspension polymerization, the temperature rising time from room temperature to the reaction temperature is preferably in the range of 20 to 90 minutes. This is because if the time is less than 20 minutes, the crosslinking of the resin is not sufficient, and if the temperature is raised for more than 90 minutes, the molecular weight of the resin cannot be reduced.

Next, after the suspension polymerization is completed, 8
The alkali treatment is performed at a temperature of 5 ° C or higher, preferably 88 ° C or higher. This is because benzoic acid generated due to the polymerization initiator is reduced and the charging stability of the resin is improved. Examples of the alkali used include hydroxides of alkali metals such as lithium, sodium, potassium and rubidium, and sodium hydroxide is particularly preferable. The amount of alkali used is 0.1 to 2% by weight, particularly preferably 0.1% by weight, based on the total amount of the components (a) to (c).
It is in the range of 3 to 1.5% by weight.

In the above suspension polymerization, after completion of the polymerization, distillation is carried out before or at the same time as alkali treatment and residual monomers are removed from the system together with deionized water at a temperature of 100 ° C. or higher. Can be distilled. The amount to be distilled off is 5 to 30% by weight, particularly preferably 10 to 25% by weight, of the amount of deionized water used for suspension polymerization.

The resin for toner of the present invention produced by the above method has a glass transition temperature of 50 to 70 ° C., preferably 53 to 67 ° C., a softening temperature of 120 to 185 ° C., preferably 125 to 180 ° C. Fraction 15 to 50%, preferably 17 to 47%, acid value 10 to 20 mgKOH /
g, preferably 11 to 19 mgKOH / g, it is important that the molecular weight of the maximum peak in the molecular weight distribution by GPC of the solvent-soluble polymer is 10,000 or less, preferably 9000 or less.

This is because (1) a toner using a resin having a glass transition temperature of less than 50 ° C. has poor blocking resistance, while a toner using a resin having a glass transition temperature of more than 70 ° C. has poor fixability. (2) A toner using a resin having a softening temperature of less than 120 ° C. is inferior in non-offset property, while a toner using a resin having a softening temperature of more than 185 ° C. has a lower fixing property. (3) The toner using a resin having an acid value of less than 10 mgKOH / g becomes deteriorated in the image in a large amount of printing.
On the other hand, a toner using a resin exceeding 20 mgKOH / g has a high chargeability and a low image density. (4) A toner using a resin having a gel fraction of less than 15% is inferior in non-offset property, while a toner using a resin in which the gel fraction is more than 50% is inferior in fixing property. (5) Toner using a resin having a maximum peak molecular weight of more than 10,000 in the GPC molecular weight distribution of the solvent-soluble polymer has a low fixing property. It is because of the reason such as.

[0024]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. The performance evaluation in the examples was performed using the following methods. In addition, "part" in the examples is "part by weight"
Indicates.

(1) Glass transition temperature (Tg) (° C.) Using a differential scanning calorimeter manufactured by Shimadzu Corporation, a temperature rise of 10
The contact point between the tangent line of the endothermic curve near Tg measured at ° C / min and the base line was taken as Tg.

(2) Softening temperature (° C.) Shimadzu Corporation Flow Tester (CFT-50)
0) is used, the temperature at the time when half the sample flows out under the conditions of a nozzle of 1.0 mmφ × 10 mmL, a load of 30 kgf, a temperature increase of 3 ° C./min, and a sample amount of 1.0 g, the softening temperature (° C.)
And

(3) Acid value (mgKOH / g) The resin was heated and dissolved in benzyl alcohol and then cooled,
Titration was performed with a 1/50 normal KOH benzyl alcohol solution.

(4) Gel Fraction (%) 0.5 g of a sample was put in 50 ml of tetrahydrofuran and dissolved by heating at 60 ° C. for 3 hours, and then Celite (Johns) was used.
-Manville Salees # 545) was filtered through a glass filter and 80 ° C. in a vacuum dryer.
The value obtained by dividing the weight when fully dried with the initial weight was used.

(5) Measurement of molecular weight distribution by GPC (gel permeation chromatography) Using GPC HCL-8020 manufactured by Tosoh Corp., a calibration curve prepared with a monodisperse polystyrene standard sample and the counted values The molecular weight was calculated and the molecular weight distribution was determined from the relationship. The sample used was obtained by dissolving and extracting the resin with a solvent (tetrahydrofuran).

(6) Toner fixing property, non-offset property,
Image Stability The fixability, the non-offset property, and the image stability were evaluated using a copying machine having a fixing speed of 200 mm / sec and a fixing temperature that was freely variable.

(A) Fixability The initial density is 1.2 to 1.3, the ratio between the density after rubbing with a sand eraser and the initial density is determined, and the temperature at which it exceeds 85% is defined as the fixing temperature. . A: Excellent (fixing temperature of less than 170 ° C) B: Slightly inferior (fixing temperature of 170 to 180 ° C) X: Inferior (fixing temperature of 181 ° C or higher)

(B) Non-offset property The offset generation temperature was evaluated. ◯: Excellent (offset generation temperature of 210 ° C or higher) Δ: Slightly inferior (offset generation temperature of 200 to less than 210 ° C) ×: Inferior (offset generation temperature of less than 200 ° C)

(C) Image stability 20,000 sheets were printed by the above copying machine and the image quality was visually judged. ○: excellent (image density does not decrease) Δ: slightly inferior (image density slightly decreases) ×: inferior (image density significantly decreases)

(7) Toner blocking resistance 5 g of the toner was placed in a 50 ml glass sample bottle,
After leaving it in a hot air dryer at 50 ° C. for 70 hours, it was cooled to room temperature and the degree of aggregation was observed. ○: excellent (the toner is uniformly dispersed when the sample is upside down and hit) Δ: somewhat inferior (the toner is uniformly dispersed when the sample is inverted and hit three times) ×: poor (the sample is inverted and strong vibration is applied) The toner does not aggregate and disperse.)

Example 1 220 parts of deionized water, 0.2 part of polyvinyl alcohol,
0.03 part of hydrogen peroxide was sufficiently mixed and charged into a reaction vessel equipped with a distillation column and a stirrer. Then, styrene, n-butyl acrylate, methacrylic acid and divinylbenzene in the amounts shown in Table 1 were added and stirred at a rotation speed of 350 rpm. Then, after adding the amount of the polymerization initiator shown in Table 1,
Stirring was continued for about 1 hour and the reaction vessel was sealed.
Then, the temperature rise of the reaction system was started. About 45 minutes after the start of heating, the temperature in the reaction system reached 135 ° C. Then, the reaction temperature and the reaction pressure (3.5 kg / cm ² ) were kept constant and these conditions were maintained for about 4 hours and 30 minutes. Next, the temperature in the reaction system was lowered to 90 ° C., the pressure inside the reaction vessel was set to normal pressure, and the stirring rotation speed was set to 400 rpm.

Then, the temperature in the reaction system is set to 1 by heating again.
The temperature was raised to 00 ° C., and a mixed liquid of deionized water and residual monomer volatilized from the reaction system was distilled out of the reaction system. Approximately 2 hours after the start of distillation, when the amount of distillate reached 44 parts, the temperature in the reaction system was lowered to and maintained at 90 ° C., and 0.5 part of sodium hydroxide was added. After dropping sodium hydroxide and about 60 minutes passed, the temperature in the reaction system was cooled to room temperature, and the rotation speed was set to 100 rpm. Next, the resin beads were taken out of the reaction vessel, thoroughly washed with deionized water, dehydrated and dried for about 48 hours in a dryer kept at 50 ° C. to obtain resins A to L. Resin A obtained
The characteristic values of L are shown in Table 1.

Next, carbon black (# 40, manufactured by Mitsubishi Kasei Co., Ltd.) 5 was added to 91 parts of the above resins A to L.
Part, polypropylene wax (manufactured by Sanyo Kasei Co., Ltd., 55
0P) 3 parts, and a charge control agent for negative charging (Orient Chemical Co., Ltd., S-34) 1 part are thoroughly mixed, and then
Using an internal mixer (manufactured by Kurimoto Tekko Co., Ltd.), the resin temperature during kneading was controlled to be 20 ° C. higher than the softening temperature, and kneading was performed for about 30 minutes. The obtained toner lumps are roughly crushed and finely crushed by a jet mill, and then the particle size of the toner is adjusted by using a classifier so that the particle size is 5 to 20 μm and the charge amount after mixing with the ferrite carrier for 30 minutes is 20 μC / g
Toners AT to LT were obtained. These toners AT to LT
Table 2 shows the evaluation results of the above. The charge amount (μC
/ G) was acclimated to the environment for 48 hours in a thermo-hygrostat at 20 ° C. and 60% RH, stirred for 20 minutes, and measured with a blow-off charge amount measuring device (manufactured by Toshiba Chemical Co., Ltd.).

[0038]

[Table 1]

[0039]

[Table 2]

As is clear from Table 2, when the resins A to L are used as toners, they are excellent in fixing property, non-offset property, blocking resistance and image stability.

Example 2 Resins M to N were obtained in the same manner as in Example 1 except that the polymerization composition was as shown in Table 3. Table 3 shows the characteristic values of the obtained resins M to N. Next, the same operations as in Example 1 were performed using the resins M to N to obtain toners MT to NT. Table 4 shows the evaluation results of the obtained toners MT to NT. As is apparent from Table 4, when the resins M to N are used as the toner, the fixing property, the non-offset property, the image stability, and the blocking resistance are excellent.

[0042]

[Table 3]

[0043]

[Table 4]

Comparative Example 1 Resins CA to CD were obtained in the same manner as in Example 1 except that the polymerization composition was as shown in Table 5. Obtained Resin CA ~
Table 5 shows the characteristic values of CD. Next, the above resins CA to CD
The same operation as in Example 1 is performed using the toners CAT to C
I got DT. Table 6 shows the evaluation results of the obtained toners CAT to CDT. Since the resin CA has a low acid value, the initial charge amount of the toner CAT was adjusted to 20 μC / g.
The charge amount after printing 50,000 sheets was reduced to 15 μC / g and the image stability was poor. Since the resin CB has a high acid value, the charge amount of the toner CBT at the initial concentration is as high as 35 μC / g, and a sufficient image density cannot be obtained from the initial stage, resulting in poor image stability. Resin CC has Tg, softening temperature,
Due to the low gel fraction, the toner CCT was inferior in non-offset property and blocking resistance. Since the resin CDT has high Tg, softening temperature, gel fraction and molecular weight, the toner C
DT had poor fixability.

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

The negatively chargeable toner resin of the present invention having the constitution as described above is excellent in fixing property, non-offset property, image stability and blocking resistance, and is suitable for electrophotography, electrostatic It is extremely useful as a toner resin for copiers, printers, facsimiles and the like used in the printing method.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C08F 220/06 MLU 8619-4J 220/12 MLZ

Claims (1)

[Claims] 1. A peroxide-based polymerization of a monomer mixture comprising (a) aromatic vinyl, (b) (meth) acrylic acid, (c) (meth) acrylic acid ester and (d) polyfunctional compound. A copolymer obtained by polymerization in the presence of an initiator, having a glass transition temperature of 50 to 70 ° C and a softening temperature of 12
0 to 185 ° C., acid value is 10 to 20 mgKOH / g, gel fraction is 15 to 50%, and the maximum peak molecular weight in the molecular weight distribution of the solvent-soluble polymer by gel permeation chromatography is 10,000 or less. Resin for toner characterized by the above.