JPS58118651A - Dry developing toner for heat fixing - Google Patents

Abstract

PURPOSE:To improve offset resistance, heat resistance, etc. by using a copolymer of arom. vinyl and ethylenic unsatd. alkyl monocarboxylate as a thermoplastic resin medium and specifying the properties of the copolymer. CONSTITUTION:Styrene/n-butyl methacrylate/2-ethyl hexyl acrylate (70/20/10 based on weights of monomers) are emulsion polymerized whereby a copolymer of arom. vinyl and ethylenic unsatd. alkyl monocarboxylate is obained. Such copolymer having property values of >=50,000 weight average mol. wt., 60-80 deg.C glass transition point, and 5-25g/10mm. melt index (ASTMD-1238, 150 deg.C) is used as a thermoplastic resin medium for dry developing toners for heat fixing. Coloring agents, etc. are compounded with the resin medium, whereby a dry developing toner is obtined. Thus, the dry developing toner having heat resistance, blocking resistance, and offset resistance as well as good heat fixability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry printing toner for heat fixing which has an excellent combination of offset resistance, heat resistance, blocking resistance, fluidity and fixing properties.

In the field of electrophotography, heat and pressure bonding using a roller is advantageous in terms of thermal efficiency, prevention of fire accidents, and fixing operation for thermally fixing toner particles onto copy paper, but Because the toner particles come into contact with the toner under heat and pressure, a so-called offset phenomenon occurs in which some of the toner particles adhere to and transfer to the surface of the fixing roller, and these particles transfer onto the close-up paper again, causing stains on the copy paper. becomes a problem.

Several methods have been used to prevent such defects, and one typical method is to make the surface of the fixing roller with a material that is releasable or stain resistant, such as fluororesin. At the same time, a thin film of anti-offset liquid such as silicone oil is formed on the surface, but this method complicates the mechanism of the fixing device and requires the anti-offset liquid during fixing. Another typical method involves pre-containing a substance that acts as a release agent in toner particles, and when fixing with a roller,
The purpose is to release the substance in liquid form on the particle surface, thereby preventing the offset phenomenon. However, in this latter method, the desired effect cannot be obtained unless a fairly large amount of release agent is contained in the toner particles, and this also causes a decrease in fluidity due to toner blocking and a decrease in heat resistance. , spent, and toner (decrease in carrier physical properties due to resin adhesion to the carrier), and these troubles can be ignored because the release agent easily migrates to the toner particle surface (immigration). It becomes something that does not exist.

When considering the offset phenomenon that occurs when the toner is fixed by the heating roller, the causes can be roughly divided into the following two types.One is that the toner particles are completely melted, but the molten toner is not absorbed by the roller. There is a case where the adhesion to the molten toner is greater than the cohesive force of the molten toner, resulting in transfer to the roller surface (hot offset).The other case is that the toner particles are melted by the heating roller, but This is a case where the copy paper side is in a non-solvent or non-softened state, and as a result, transfer to the roller surface occurs (cold offset).

All offset prevention methods that have been proposed so far have aimed at preventing toner from adhering to the heating roller, and have been based on the cohesive force of toner particles in a molten state and the fixability at relatively low temperatures. From this point of view, there is little to be found that attempts to prevent offset.

Accordingly, an object of the present invention is to provide a dry developing toner for heat fixing that has an excellent combination of offset resistance, heat resistance, blocking resistance, fluidity, and fixability.

Another object of the present invention is to provide a dry developing toner for heat fixing that prevents the above-mentioned hot offset and cold offset and also provides excellent fluidity even at relatively high temperatures.

Still another object of the present invention is to provide a one-component magnetic toner for heat fixing that has an excellent combination of the above characteristics.

According to the present invention, in the dry developing toner for heat fixing comprising a composition of a thermoplastic resin medium and a pigment dispersed in the medium, the thermoplastic resin medium has a weight average molecular weight of 50, LI00 or more, 60 glass transition temperature of ˜80C;
Melt index CAS of 5 to 25j'/1[J-
"rMD-1268, 150C) and 120 to 160
A dry developing toner for heat fixing is provided, which is characterized in that it is made of a copolymer of an aromatic vinyl having a softening point of C (ring and ball method) and an ethylenically unsaturated monocarboxylic acid alkyl ester.

In the present invention, a copolymer of aromatic vinyl and an ethylenically unsaturated monocarboxylic acid alkyl ester is used as a thermoplastic resin medium of a dry developing toner for heat fixing. (1) 50,000 or more, especially 6 [JUOO to 200
Weight average molecular weight of 0LIO
"W" by Kufumatography (GpC method) 1.(
i+) Glass transition temperature (rg) of 60-80C1, especially 66-76C, (ill) 5-25 f/1
(Jwrix, especially melt index Cd of 8 to 20 f/10, 1.] and 120 to 16 DC'
It is particularly important to use S having a softening point of 125 to 155C.

When toner is thermally fixed by a heating roller, if the area where the offset phenomenon occurs is plotted using the roller temperature and contact time with the roller as both axes, the high temperature side and the long time side are generally the hot offset area, and the low temperature side and short time side are the cold offset areas. There is one non-offset fixing area between these two areas, and the width of this non-offset fixing area varies depending on the type of resin. In the present invention,
By selecting the above-mentioned various physical properties within the above ranges, it becomes possible to significantly increase the range of this non-offset domain.

That is, as the molecular weight of the resin used increases, the hot offset region shifts toward higher temperatures and longer times, but along with this, the cold offset regions also shift toward higher temperatures and longer times. There is a tendency for this to increase.

Also, the lower the softening point of *W# used, the more the cold offset region shifts to the lower temperature side and shorter time side.
Along with this, the hot offset region also tends to shift to a lower temperature side and a shorter time period.

In the present invention, the weight average molecular weight of the copolymer of aromatic vinyl and ethylenically unsaturated monocarboxylic acid alkyl ester is 5oooo or more, and the softening point is 120 to 160C.
range, and the copolymer (DM, 1. is 5 to 2
By setting 5P/10m and the glass transition temperature in the range of 60 to 80C, the cold offset region is shifted to the low temperature short time side, the hot offset region is shifted to the high temperature long time side, and the range of the non-offset fixing region is changed from the conventional one. It is possible to significantly expand the size compared to toner.

For example, M, 1. If the value of is above the above range, there is a greater tendency for hot offsets to occur, while if it is smaller than the above range, there is a greater tendency for cold offsets to occur.

Furthermore, when J/y is smaller than the above range or when the softening point is smaller than the above range, the heat resistance of the toner decreases and the blocking tendency of the toner particles increases. Also hf
, 1. is lower than the above range, or when the softening point is higher than the above range, there is a tendency for the fixing properties to decrease. Furthermore, if rq is lower than the above range, the toner particles will tend to block, while if rq is higher than the above range, problems of poor fixing will likely occur.

It is also important to use a copolymer of aromatic vinyl and an alkyl ester of an ethylenically unsaturated monocarboxylic acid as the K that matches the above-mentioned properties of the fixing resin medium with the range specified in the present invention. Hot offset tends to occur when low molecular weight polystyrene, polyamide resin, epoxy resin, and petroleum resin resins are used, and cold offset occurs when other resins such as high molecular weight polystyrene and acrylic homopolymers are used. There is a tendency to cause

As the aromatic vinyl monomer used in the copolymer of the present invention, in the following formula, R is a hydrogen atom, a lower alkyl group (having 4 or less carbon atoms), or a halogen atom, and R1 is a lower alkyl group. , is a substituent such as a halogen atom, and ru is 2 including zero.
Examples of monomers represented by the following integers include styrene, vinyltoluene, α-methylstyrene, α-chlorostyrene, vinylxylene, and vinylnaphthalene.

Among these, styrene and vinyltoluene are preferred.

As the other ethylenically unsaturated monocarboxylic acid alkyl ester monomer, R.

■ In the formula, R1 is a hydrogen atom or a lower alkyl group, and R
4 is an alkyl group having up to 18 carbon atoms. Examples of monomers represented by the formula include ethyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate.

In the present invention, by copolymerizing at least one type of aromatic vinyl and at least one type of acrylate or methacrylate, the glass transition temperature and softening point can be maintained within the above range while increasing the molecular weight. Particularly suitable resins for the purpose of the present invention include styrene or vinyltoluene and acrylate or methacrylate.
Weight ratio of 50:50 to 8Ll:20, especially 60:4U
It is a resin formed by copolymerizing at a weight ratio of 75:25, and among these, acrylate or methacrylate having an alkyl group with up or down 4 carbon atoms and an alkyl group with 6 or more carbon atoms are used as acrylate or methacrylate. It is preferable to use them in combination with acrylate or methacrylate in a weight ratio of 5:95 to 9[1:10, special KID: 90 to 85:15.

An example of a suitable copolymer is styrene/butyl acrylate)
/2-ethylhexyl acrylate, styrene/ethyl acrylate/2-ethylhexyl methacrylate, styrene/butyl methacrylate)/2-ethylhexyl acrylate, styrene/butyl methacrylate/decyl acrylate, styrene/butyl acrylate/2- Ethylated hexyl acrylate, styrene/butyl acrylate/butyl methacrylate/2-ethylhexyl acrylate, vinyltoluene/butyl methacrylate)/2
- When an acrylate or methacrylate having a long-chain alkyl group such as 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate is introduced into the copolymer, the molecular weight is high. Acrylates and methacrylates having a lower alkyl group have the remarkable advantage of preventing cold offset and providing good heat fixing properties at relatively low temperatures, while acrylates and methacrylates having a lower alkyl group have the effect of preventing hot offset.

Of course, this copolymer can be used within a range that does not impair its essence.
That is, comonomers such as conjugated diolefin, acrylic acid, methacrylic acid, vinyl esters, vinylpyridine, maleic anhydride, etc. may be copolymerized within a range not exceeding 5% by weight of the total.

In the present invention, as the pigment, 181 or a combination of two or more of coloring pigments, extender pigments, magnetic pigments, and conductive pigments can be used. Of course, these pigments may also be pigments that have two or more of the above-mentioned functions; for example, carbon black has the function of a conductive pigment as well as a black pigment, and triiron tetroxide has the function of a magnetic pigment. At the same time, it also has the function of a black pigment, which is clear from its name, so-called iron black.

Suitable examples of colored pigments are as follows.

Black pigments carbon black, acetylene black, lamp black, aniline black.

Yellow pigment yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S1 C:/f-1 yellow G
, Han f-ye o-1oG.

Benzidine Yellow 01 Benzidine Yellow GR.

Quinoline Yellow Lake, Permanent Niro NCG, Tartrazine Lake.

Orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, palkan orange, indanthrene brilliant orange Rf, benzidine orange G1 indanthrene brilliant orange GK0 red pigment red pigment, cadmium red, red lead, mercury cadmium sulfide, °Permanent Red)", 4R, Resole Red,
Pyrazolone Red, Watching Red Calcium Salt, Lakelet D, 7' IJ Leant Carmi 76
B, Eosin Lake, Rhodamine Lake B1 Alizarin Lake, Prilliant Carmine 6B0 Purple Pigment Manganese Purple, Fast Violet B1 Methyl Violet Lake 0 Blue Pigment Dark Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, 7 Talo, Cyanine Blue, Metal-free Phthalocyanine Blue, Partially Chlorinated Phthalocyanine Blue, Fast Sky Blue, Indan Stremburu-B
C0 Green pigment chrome green, chromium oxide, pigment green B1
Malachite Green Lake, Final Yellow Green G0 White pigments zinc white, titanium oxide, antimony white, zinc sulfide 0 extender pigment pallite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

As a magnetic material pigment, conventionally, for example, triiron tetroxide (F 0
4), iron sesquioxide (γ-FsuOa), iron zinc oxide (ZT
LFg, O, ), iron yttrium oxide (Y, Fsu0at
), iron cadmium oxide (CdF~04), iron gadolinium oxide (Gd, Ft, 0.t) iron oxide steel (CuFa
20J, iron lead oxide (Ph”It”I), iron nickel oxide (NiF04), iron neodymium oxide (NdFaQs)
), barium iron oxide (BcL/4t (4s), magnesium iron oxide CMqFg, Q, ), iron manganese oxide (M
n F gt ()a ), lanthanum iron oxide (LaFe
Although iron powder (F), cobalt powder (Co'), nickel powder (N), etc. are known, any of these known fine powders of magnetic materials may be used in the present IM. A particularly suitable magnetic material pigment for the purposes of the present invention is triiron tetroxide.

As the conductive pigment, in addition to the above-mentioned carbon black, any material that is subjected to conductive treatment, such as inorganic fine powder or various metal powders that are themselves non-conductive, can be used.

The blending amount of the pigment can be within a wide range depending on the use of the toner, and generally within the range of 1 to 300% by weight of the fixer resin. For applications as toners used in these ranges, it is preferable to use coloring pigments of 1 to 15 weight tS, especially 2 to 10 weight tS per fixer, while for use as one-component magnetic toners. For this purpose, it is preferable to use 50 to 600 by weight of magnetic material pigment and 60 to 250 by weight of magnetic material pigment per fixer resin, in combination with coloring agent pigment and conductive agent pigment, if necessary.

Other compounding agents known per se can be added to the toner of the present invention according to known formulations.

For example, for use as a electrostatic toner, charge control agents known per se, such as nigrosine base (C15045
), oil black (C/26150), spirone black, and other oil-soluble dyes, nanthenic acid metal salts, fatty acid metal soaps, resin acid soaps, metal-containing azo dyes, etc., in an amount of 0.1 to 5% by weight per fixing agent. It can be blended in an amount of Also, silicone oil, low molecular weight olefin resins, various waxes, etc. may be used to assist in mold release.

After kneading the above-mentioned shida copolymer and pigment and cooling the mixed wire composition, it is ground and sieved to remove IK and K) to obtain a powder. Of course, there is no particular problem even if rapid mechanical stirring is used to round off irregularly shaped particles.

Although the particle size of the toner particles is related to the release force and the like, it is generally desirable that the particle size is in the range of 5 to 35 microns.

In the electrostatographic reproduction method using the toner of the invention, the formation of the electrostatic latent image can be carried out in any manner known per se, for example after uniformly charging the photoconductive layer on the conductive substrate. An electrostatic latent image can be formed by imagewise exposure.

The development of Seiden Lun can be carried out more easily in the case of -component magnetic toner as it is, or in the case of two-component toner by mixing it with a magnetic carrier and bringing the magnetic brush of this toner into contact with the substrate. . The toner image formed by development is transferred onto the copy paper, and the toner image is brought into contact with a heating roll to be fixed.

As mentioned above, the dry toner of the present invention has a wide non-offset fixing area, so even when the hot roll fixing conditions vary within a wide range, it can achieve good fixing performance without causing offset phenomenon. Furthermore, it has the advantage of having good heat resistance and fluidity.dThis advantage is particularly remarkable in the case of a toner having a small amount of resin per total amount of toner, such as a -component magnetic toner.

The invention is illustrated by the following example.

Example 1 Styrene/rL-butyl methacrylate/2-ethylhexyl acrylate (monomer weight ratio near D/2
Weight average molecular weight (My) 93000° Glass transition temperature CT, q) 70 C, Melt index (
, M, I) t3f710m, softening point (S, P) 14
7C) 2[JO parts by weight (hereinafter abbreviated as parts), 16 parts of carbon black (Special Black 4 manufactured by Degussa) and 4.6 parts of a negative charge control agent (Spiron Black TOII manufactured by Hoiyo Kagaku Kogyo) were added to a sufficient amount. After mixing, the mixture is cross-melted using a two-roll mill, and after being left to cool, it is coarsely ground using a cutting mill to obtain a particle size of 0.5 to 2 square centimeters. Next, the toner is finely pulverized using a jet mill and then classified using a zigzag classifier to obtain a toner having a particle size of 5 to 25 μm (volume 5.0% diameter: 12 μm). Hydrophobic silica (Nippon Aerosil Co., Ltd. #!R-972) was mixed in an amount of 8.1% to the total weight of the toner to perform surface treatment.

920 parts of carrier iron powder (200/300 made by Nippon Steel Powder) and 80 parts of toner were mixed, and a commercially available copier (DC-161,
A copying test was conducted using a copying machine (manufactured by Sanda Kogyo).

The hopper of the current G1 copying machine was filled with the above toner as replenishment toner, and 50,000 copies were made, but the image density remained at 1.4 (reflection density or higher), and the fog density was an absolute density. 0.02 or less, but during this period, a constant landing (
The upper roller is made of Teflon and the lower roller is made of silicone rubber. Although maintenance was never performed on the heater roller, a copolymer synthesized by omitting one of the acrylic components from the above copolymer composition was used. When using toner manufactured by
Cleaning of the lower fixing roller was required.

Example 2 Anti-magnetic cuff 0 oersted, bulk density 0.46 fed 220 parts by weight of magnetite with a particle size of 0.4μ (hereinafter referred to as parts), 5 parts of mold release agent (low molecular weight polypropylene, manufactured by Sanyo Chemical Industries, Ltd.), negative 2.4 parts of a charge control agent (manufactured by Orient Chemical Industry Co., Ltd., Bontron) and 180 parts of the copolymer shown in Table 1,
The mixture is melted using this roll, and after being left to cool, it is coarsely ground using a cutting mill to a size of 5 sL2 rows. Next, the powder is finely pulverized using a jet mill and classified using a zigzag classifier to obtain a magnetic toner having a particle diameter of 5 to 25 μm (center particle size: 11 μm).

A surface treatment was carried out by mixing 0.2 g of hydrophobic silica with respect to the total weight of the toner.

The coercive force was measured using a magnetic property measuring device (Model V) manufactured by Toei Kogyo.
Measured using SMP-1 type, magnetic field 5 (Oersted),
The bulk density was determined according to JIS-5101, and the magnetite particle size was determined from electron microscope photography.

The following tests were conducted using these prepared magnetic toners.

In a copying machine that uses a selenium drum (outer diameter 150 m+) as a photoreceptor, the strength of the magnetic field on the developing sleeve (outer diameter 33 ws) containing a built-in magnet via a non-magnetic member is set to approximately 90.0 Gauss. The above magnetic toner was deposited on a developing roller using a so-called internal rotation system in which the magnet and sleeve could be rotated independently and individually, with a spacing of 0.3 ms between the cutting plate and the sleeve, and the magnetic toner was developed from a hopper. It was arranged so that it could be supplied to a portion of the roller, and the distance between the surface of the photoreceptor and the developing roller was 0.5 m. The developing sleeve and photoreceptor rotate in four directions, and the magnet rotates in the opposite direction.
), exposure, - development, transfer C + 6.5KV), constant fixation of the heater roller and fur brush cleaning.
The 0 test method uses high-quality paper with a thickness of 80 μm and makes multiple copies at each temperature while changing the temperature of the heater roller. Examine the effects of cold offset (abbreviated as CC, O) or hot offset (abbreviated as H, O) on second and subsequent copies (the offset tner is transferred), and check the occurrence of cold or hot offset. I checked the temperature.

In addition, the blocking temperature (abbreviated as B, T) is
was left open for 4 hours, and the temperature was checked when cohesiveness was visually observed. Furthermore, for the fixability of copies (abbreviated as F), the residual image density is 95% or more after fixing at a heater roller surface temperature of 170 C and peeling off cellophane tape at the fixed area. evaluated.

The test results are shown in Table 2.

Table 1 Note) Numbers in the table indicate monomer weight ratios, and these copolymers were synthesized by emulsion polymerization.

According to the results in Table 2, in the present invention, the thermoplastic resin medium has a weight average molecular weight of 50,000 or more, 60 to 80C.
glass transition temperature of 5 to 25 f/10 dark melt index (ASTMD-12, 38° 150C) and 1
Offset resistance, Blocking resistance,
It was confirmed that a toner having physical properties excellent in heat resistance and fixing properties could be obtained. In addition, these toners did not exhibit cohesiveness and had excellent fluidity.

Patent applicant: Sanda Kogyo Co., Ltd.

Claims (1)

[Claims] (1) In a dry soap toner for heat fixing comprising a composition of a thermoplastic resin medium and a pigment dispersed in a pigment medium, the thermoplastic resin medium has a weight average molecular weight of 50,000 or more, and a weight average molecular weight of 60 to 80C. glass transition temperature of 5 to 25
Melt index of f/10■ (ASTMD-125
A dry current toner for heat fixing characterized by being composed of a copolymer of an aromatic vinyl having a ring and ball ring and an ethylenically unsaturated monocarboxylic acid alkyl ester with a softening point of 8°150c and 120 to 160c. .