JPH096046A - Resin binder for toner - Google Patents

Abstract

PURPOSE: To obtain a resin binder ensuring superior low-temp. fixability and anti-offsetting property of a toner by using a styrene-acrylic copolymer as a base and incorporating a specified wt.% of terpene resin whose softening point is a specified temp. or below. CONSTITUTION: This resin binder is based on a styrene-acrylic copolymer and contains 0.5-20wt.% terpene resin having <=125 deg.C softening point. When terpene resin having >125 deg.C softening point is used, effect of improving the low-temp. fixability of a toner is not satisfactory. The softening point is preferably <=100 deg.C. In the case of <0.5wt.% terpene resin content, effect of improving the low-temp. fixability of a toner is not satisfactory. In the case of >20wt.%, the characteristics of the styrene-acrylic copolymer as a resin binder are deteriorated. The content is preferably 3-15wt.%. The pref. number average mol.wt. of the terpene resin is 600-1,300.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder resin for a toner used for developing an electrostatic charge image or a magnetic latent image in electrophotography, electrostatic recording, electrostatic printing and the like. The present invention relates to a binder resin for a toner, which can provide a toner excellent in fixability and non-offset property at low temperature.

[0002]

2. Description of the Related Art In a typical image forming process by an electrophotographic method or an electrostatic printing method, a photoconductive insulating layer is uniformly charged, the insulating layer is exposed, and then a charge on an exposed portion is obtained. To form an electric latent image by dissipating the toner, and a developing step of visualizing the latent image by adhering a finely charged toner to the latent image, and transferring the obtained visible image to a transfer material such as transfer paper. It comprises a transfer step of transferring and a fixing step of permanently fixing by heating or pressing.

Various performances are required for the toner and the binder resin for the toner used in the electrophotographic method or the electrostatic printing method in each of the above steps. For example, in the development process, the toner and the binder resin for the toner maintain a charge amount suitable for a copying machine without being affected by the surrounding environment such as temperature and humidity in order to attach the toner to the electric latent image. I have to do it. Also,
In the fixing step by the heat roller fixing method, the non-offset property that does not adhere to the heat roller and the fixability to paper must be good. Further, it is required to have a blocking resistance so that the toner does not block during storage in a copying machine.

Conventionally, binder resins for toners include:
Styrene-acrylic resins are frequently used, and linear type (non-crosslinked type) resins and crosslinked type resins are used. In the cross-linking type binder resin for toner,
Attempts have been made to widen the molecular weight distribution by crosslinking a resin to improve the fixability and non-offset property as a toner. Further, in the linear type binder resin for toner, a high molecular weight polymer component and a low molecular weight polymer component are mixed to control the glass transition temperature and the molecular weight of both components, and the molecular weight distribution (Mw / Mw / Mn)
Attempts have been made to improve the fixing property and non-offset property of the toner by controlling the toner.

[0005]

However, in the case of a crosslinked type binder resin for a toner, simply cross-linking the resin is inferior in the balance between the fixing property and the non-offset property as a toner and has a sufficient fixing property. It was difficult to obtain a toner. Further, since the dispersibility of the pigment and the like is poor, it is necessary to disperse the pigment with a high breaking force, and as a result, there is a problem that the cross-linked structure is broken and the non-offset property is lowered. On the other hand, a toner using a binder resin for a linear toner has good dispersibility of pigments, etc., but, for example, when the fixability is improved, the melt viscosity of the binder resin for a toner is lowered and the toner is not offset. Toner with a good balance between the two
Was hard to get. Further, in recent years, from the viewpoint of energy saving and environmental protection, a toner excellent in fixability at low temperature has been demanded. Therefore, an object of the present invention is to provide a binder resin for toner which is excellent in fixing property and non-offset property at low temperature as a toner.

[0006]

In view of such circumstances, the inventors of the present invention have made earnest studies on a binder resin for toner, and as a result, have found that a terpene specific to a binder resin containing a styrene-acrylic copolymer as a main component is specified. It has been found that a binder resin for toner, which is excellent in fixing property and non-offset property as a toner, can be obtained by blending a system resin, and has reached the present invention. That is, the binder resin for a toner of the present invention is characterized by containing a styrene-acrylic copolymer as a main component and containing 0.5 to 20% by weight of a terpene resin having a softening point of 125 ° C. or lower. is there.

The binder resin for a toner of the present invention contains a styrene-acrylic copolymer as a main component and a terpene resin having a softening point of 125 ° C. or less in an amount of 0.5 to 20% by weight. Is. The terpene-based resin used in the present invention is not particularly limited, and for example, terpene oil, β-pinene, an ordinary terpene obtained by adding an acid to a terpene such as dipentene as a catalyst, and polymerizing the terpene. Resins with a softening temperature of 1
The thing below 25 degreeC can be used. This is because when a pelten resin having a softening temperature of higher than 125 ° C. is used, the effect of improving fixability at low temperature as a toner becomes insufficient, and the range is preferably 100 ° C. or lower.

In the present invention, the content of the terpene resin needs to be in the range of 0.5 to 20% by weight. This is because when the content of the terpene resin is less than 0.5% by weight, the effect of improving the fixability at low temperature as a toner becomes insufficient, and when it exceeds 20% by weight, the styrene-acrylic copolymer is conversely. This is because the properties as a binder resin are impaired, and the range is preferably 3 to 15% by weight. Also, as the terpene-based resin used,
The number average molecular weight is preferably in the range of 600 to 1300, and more preferably in the range of 600 to 900.

The styrene-acrylic copolymer used as the main component of the binder resin for toner of the present invention is a styrene-acrylic copolymer composed of a styrene monomer and a copolymerizable acrylic monomer. Is. In the present invention, the styrene-based monomer used for polymerization of the styrene-acrylic copolymer includes styrene and o-
Methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-ethyl styrene, 2,
4-dimethylstyrene, pn-butylstyrene, p-
tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-densyl styrene, pn-dodecyl styrene, p-phenyl styrene, 3,4- Examples thereof include dicyclosyl styrene, and among them, styrene is preferable. These styrene monomers can be used alone or in combination of two or more.

The copolymerizable acrylic monomers include ethyl acrylate, methyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate and meta. Acrylic acid, ethyl methacrylate, methyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, propyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, and other acrylic acid esters are included. .

Further, unsaturated dicarboxylic acid diesters such as dimethyl maleate, diethyl maleate, butyl maleate, dimethyl fumarate, diethyl fumarate and dibutyl fumarate, unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and cinnamic acid. Unsaturated dicarboxylic acids such as acid, maleic acid, fumaric acid, itaconic acid, monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monoesters of unsaturated monocarboxylic acid such as monobutyl fumarate, etc. The carboxylic acid-containing vinyl monomer can be used in combination.

The copolymerization ratio of these monomers is not particularly limited, but it is preferably selected so that the glass transition temperature of the resulting binder resin for toner is in the range of 45 ° C. or higher. This is because when the glass transition temperature of the binder resin for toner is lower than 45 ° C., the blocking occurrence temperature of the toner is lowered and the storage stability tends to be extremely lowered. More preferably, it is in the range of 50 to 70 ° C. because the fixing property as a toner tends to decrease.

The styrene-acrylic copolymer of the present invention preferably has a softening temperature in the range of 110 to 160 ° C. When the softening temperature is less than 110 ° C., it is inferior in non-offset properties as a toner, On the other hand, if the temperature exceeds 160 ° C., the fixing property as a toner is deteriorated, and the temperature is preferably 115 to 140 ° C. In addition, styrene-
The acrylic copolymer is preferably composed of a high molecular weight copolymer and a low molecular weight copolymer, specifically,
High molecular weight copolymer having a weight average molecular weight of 200,000 to 1,500,000 and its weight average molecular weight of 2,000 to
It is composed of a low molecular weight copolymer of 50,000, and the content of the high molecular weight copolymer is in the range of 20 to 70% by weight.

This is because when the weight average molecular weight of the high molecular weight copolymer is less than 200,000, the non-offset property as a toner tends to decrease, and conversely 1,500,0.
This is because if it exceeds 00, the fixability as a toner tends to decrease, and more preferably 200,000 to 7
It is in the range of 0,000, particularly preferably 220,0.
The range is from 00 to 500,000. Further, if the weight average molecular weight of the low molecular weight copolymer is less than 2,000, the mechanical strength of the binder resin for toner is lowered, and the toner tends to be in an excessively pulverized state at the time of electrification, which tends to cause fog in the image. On the contrary, when it exceeds 50,000, the fixing property as a toner tends to be deteriorated, more preferably in the range of 6,000 to 30,000, particularly preferably 9,000 to 20, The range is 000. Further, if the high molecular weight copolymer is less than 20% by weight, the non-offset property as a toner tends to be poor, and conversely if it exceeds 70% by weight, the fixability as a toner tends to be poor. More preferably 25-5
It is in the range of 0% by weight, particularly preferably in the range of 30 to 40% by weight.

The polymerization of these polymerizable monomers can be carried out by a known polymerization method such as a suspension polymerization method, a solution polymerization method, an emulsion polymerization method or a bulk polymerization method, but there is no problem of odor due to the residual solvent, and The suspension polymerization method is preferable from the viewpoints that the heat generation is easily controlled, the amount of the dispersant used is small, and the moisture resistance is not impaired. In particular, the obtained toner binder resin is preferably composed of a uniformly mixed high molecular weight polymer component and low molecular weight polymer component, and suspension polymerization of the high molecular weight polymer component is performed. It is preferable to carry out polymerization by a polymerization method such as a two-stage suspension polymerization method in which suspension polymerization of a low molecular weight polymer component is carried out in the presence of suspended particles of a high molecular weight polymer component. The method for producing the binder resin for toner of the present invention by the two-step suspension polymerization method will be described below.
This will be specifically described. Suspension polymerization of high molecular weight polymer components
It is not particularly limited and can be carried out according to a general suspension polymerization method, and together with the above-mentioned monomers, a dispersant, a polymerization initiator and a molecular weight modifier which are generally used in suspension polymerization. Etc. can be used.

As the polymerization initiator used for suspension polymerization of the high molecular weight polymer component, a compound having three or more t-butylperoxide groups in one molecule or a 10-hour half-life temperature of 90 to 140 ° C. It is possible to use a radical polymerization initiator having one functional group in one molecule. For example, as a compound having three or more t-butyl peroxide groups in one molecule, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane and the like can be mentioned. The 10-hour half-life temperature is 90-140.
Examples of the radical polymerization initiator having one functional group in one molecule at ° C include t-butyl peroxy laurate, t-butyl peroxy 3,5,5-trimethylhexanoate,
Cyclohexanone peroxide, t-butylperoxyisopropyl carbonate, t-butylperoxyacetate, t-butylperoxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, diisopropylbenzene hydroperoxide, di-t-butylperoxide Oxide, p-methane hydroperoxide, 2
-(Carbamoylazo) isobutyronitrile, 2,2-
Organic peroxides such as azobis (2,4,4-trimethylpentane) and 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, and azo compounds. These polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator used may be a very small amount as compared with the amount of the polymerization initiator used in the conventional suspension polymerization, and 0.001 to 0.5 parts by weight based on 100 parts by weight of all the monomers. It is preferably used in the range of parts, and more preferably 0.002 to 0.05 parts by weight.

In the present invention, it is particularly preferable to use a compound having 3 or more t-butylperoxide groups in one molecule as a polymerization initiator. This is because the high molecular weight polymer component is 95 ° C. or higher, preferably 95 to 150.
At a high temperature of 100 ° C., more preferably 110 to 140 ° C., and polymerization is carried out by suspension polymerization using a compound having three or more t-butylperoxide groups in one molecule as a polymerization initiator, thereby obtaining a polymerization initiator. Is consumed efficiently,
This is because a high molecular weight polymer component having a high weight average molecular weight of 200,000 or more can be obtained in a short time of about 1 to 3 hours. Further, in the present invention, it is necessary to produce the high molecular weight polymer component by suspension polymerization at a polymerization temperature of 95 ° C. or higher. It has a polymerization temperature of 95
This is because when the temperature is lower than 0 ° C, the polymerization rate becomes slow and it takes a long time to obtain a polymer having a target molecular weight. In addition, the suspension polymerization of the high molecular weight polymer component is 0.5 to
It is preferable to carry out under a pressure of 7 kg / cm ² . The high molecular weight polymer component polymerized by suspension polymerization preferably has a weight average molecular weight (Mw) of 200,000 to 1,500,000.

Next, the low molecular weight copolymer is polymerized by suspension polymerization in the presence of suspension-polymerized high molecular weight copolymer suspension particles. The suspension polymerization is not particularly limited, and can be carried out according to a general suspension polymerization method. For example, when the polymerization reaction rate of a high molecular weight polymer becomes about 10 to 90%, a low molecular weight It is preferable to start the polymerization by dissolving and adding the polymerization initiator for the polymer to water or the monomer for the low molecular weight polymer. When the low molecular weight polymer monomer is added, the content of the low molecular weight polymer component in the obtained binder resin for toner is 30 to 8
It is preferable to add such an amount that the range is 0% by weight.

The polymerization initiator used for suspension polymerization of the low molecular weight polymer component is not particularly limited,
Usually used peroxides and azo compounds having radical polymerizability can be used. For example, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, acetyl peroxide, isobutyryl peroxide Oxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-toluoyl peroxide, t-butylperoxyacetate, t-butylperoxide Oxyisobutyrate,
t-butyl peroxypiparate, t-butyl peroxy neodecanoate, cumyl peroxy neodecanoate, t-butyl peroxy 2-ethylhexanoate,
t-butyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxylylate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, azobisisobutyl nitrile, 2,
Examples thereof include 2-azobis- (2,4-dimethylvaleronitrile). Among them, octonyl peroxide, decanonyl, and the like, from the viewpoint of the persistence of the polymerization activity for the monomer and the completion of the polymerization in a relatively short time. Peroxide, lauroyl peroxide, benzoyl peroxide and m-trioil peroxide are preferred. These polymerization initiators can be used alone or in combination of two or more,
The monomer is preferably used in the range of 0.1 to 10 parts by weight, more preferably 0.5 to 100 parts by weight.
The range is 10 parts by weight. The low molecular weight polymer component polymerized by suspension polymerization has a weight average molecular weight of 2,000 to
It is preferably in the range of 50,000.

The suspension polymerization is preferably 1 for the monomer.
With about 10 times, more preferably about 2 to 4 times water, a dispersant, a polymerization initiator, and optionally a dispersion aid or a chain transfer agent are added, and the temperature is raised to a predetermined polymerization temperature. The heating is continued until the polymerization rate reaches a predetermined level. Examples of the dispersant used in the suspension polymerization include polyvinyl alcohol, an alkali metal salt of a homopolymer or copolymer of (meth) acrylic acid, carboxytyl cellulose, gelatin, starch, barium sulfate, calcium sulfate, calcium carbonate, Examples thereof include magnesium carbonate and calcium phosphate. Among them, polyvinyl alcohol is preferable, and particularly preferable is partially saponified polyvinyl alcohol having an acetic acid group and a hydroxyl group in a block manner. These dispersants are used in an amount of 0.0
It is preferable to use it in the range of 1 to 5 parts by weight. If the amount of the dispersant is less than 0.01 part by weight, the stability of the suspension polymerization is lowered, and the polymer tends to be solidified by aggregation of formed particles, and conversely, the amount exceeds 5 parts by weight. This is because the toner tends to have a lower environmental dependency, particularly the moisture resistance, and the content is more preferably in the range of 0.05 to 2 parts by weight. If necessary, a dispersing aid such as sodium chloride, potassium chloride, sodium sulfate or potassium sulfate can be used together with these dispersants. further,
In order to adjust the molecular weight, a chain transfer agent such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 2-ethylhexyl thioglycolate, or α-methylstyrene dimer may be used, if necessary. .

[0021]

The present invention will be specifically described below with reference to examples. In the examples, the softening temperature is 1 mmφ × 10 m
Flow tester with m nozzle (Shimadzu C
FT-500), load 30 Kgf, heating rate 3 ° C
The temperature at the time when half of the sample amount flows out under the condition of / min. The number average molecular weight (Mn) and the weight average molecular weight / number average molecular weight (Mw / Mn) are values measured by gel permeation chromatography, using tetrahydrofuran as a solvent, and Tosoh HCL-802.
It was measured using 0 and calculated by polystyrene conversion.

As for the fixing temperature range, an unfixed image obtained by using a copying machine (FP-1570 manufactured by Matsushita Electric Industrial Co., Ltd.) is processed by using a fixing tester capable of freely changing process speed and roller temperature. Fix at a speed of 100 mm / sec and 400 mm / sec, and fix the resulting fixed image to JIS
Rubbing with sand eraser 9 times in accordance with 512, the image density before and after that was measured using a Macbeth densitometer, and the minimum fixing temperature at which the decrease rate of the image density was 20% or less was set as the lower limit fixing temperature, and fixing was performed. When the toner on the roller was stained, the stain due to transfer was visually evaluated, and the maximum fixing temperature at which the stain did not occur on the fixing roller was measured as the minimum upper limit temperature.

Example 1 87.5 parts by weight of styrene, n-butyl acrylate 12.
To a monomer mixture consisting of 5 parts by weight, 0.005 parts by weight of 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane as a polymerization initiator (Perkadox 12 manufactured by Kayaku Akzo Co., Ltd.) Parts are dissolved and added to a mixture of 200 parts by weight of deionized water and 0.2 parts by weight of partially saponified polyvinyl alcohol (Gosenol GH-23 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and stirred. Next, the temperature was raised to 130 ° C. and suspension polymerization of the high molecular weight polymer was performed for 1 hour. Further, in a high molecular weight polymer dispersion liquid cooled to 40 ° C.,
6 parts by weight of benzoylperoxide and 1 part by weight of t-butylperoxybenzoate (“Perbutyl Z” manufactured by NOF CORPORATION) were added, and the temperature was raised to 130 ° C. for 1 hour to carry out suspension polymerization of a low molecular weight polymer. I went. Then, it was cooled to room temperature, sufficiently washed with water, dehydrated and dried to obtain a styrene-acrylic copolymer in which a high molecular weight polymer component and a low molecular weight polymer component were uniformly mixed. The obtained styrene-acrylic copolymer had a softening temperature of 130 ° C. and an Mw / Mn of 26.
Nine.

Obtained styrene-acrylic copolymer 8
4.5 parts by weight have a softening temperature of 85 ° C. and a number average molecular weight of 7
8.5 parts by weight of 50 terpene-based resin, 5 parts by weight of carbon black (# 40 manufactured by Mitsubishi Kasei), charge control agent for negative charging ("Bontron S-34" manufactured by Orient Chemical Industry Co., Ltd.) 1
Parts by weight and 1 part by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed and melt-kneaded at 110 ° C. for 30 minutes and then at 105 ° C. for 30 minutes. Then, pulverize with a jet mill pulverizer, classify and average particle size 13μ
m was obtained. The softening temperature and the fixing temperature range of the obtained toner are as shown in Table 1, the fixing property at low temperature was excellent, and cold offset at high temperature was not recognized.

Comparative Example 1 Styrene-acrylic copolymer 8 obtained in Example 1
4.5 parts by weight of carbon black (# 4 manufactured by Mitsubishi Kasei)
0) 5 parts by weight, 1 part by weight of a charge control agent for negative charging (“Bontron S-34” manufactured by Orient Chemical Industry Co., Ltd.) and 1 part by weight of a polyolefin wax (660P manufactured by Sanyo Kasei Co., Ltd.) were mixed, and the mixture was added at 30 ° C. For 30 minutes at 105 ° C
Melt kneading for a minute. Then, the toner was pulverized using a jet mill pulverizer and classified to obtain a toner having an average particle diameter of 13 μm.
The softening temperature and fixing temperature range of the obtained toner are as shown in Table 1, and the fixability at low temperature was poor, and cold offset was observed at high temperature.

[0026]

[Table 1]

[0027]

The toner binder resin of the present invention is a mixture of a styrene-acrylic copolymer and a terpene resin to provide a toner excellent in low-temperature fixing property and non-offset property. It is possible.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Shimizu Toyohashi Plant, Sanryo Rayon Co., Ltd. 2-4-1, Ushikawa-dori, Toyohashi-shi, Aichi

Claims (1)

[Claims] 1. A terpene-based resin having a styrene-acrylic copolymer as a main component and a softening point of 125 ° C. or lower is 0.5 to
A binder resin for a toner, containing 20% by weight.