JPS59200260A - Carrier material for electrophotography - Google Patents

Abstract

PURPOSE:To improve electrostatic charging stability of a toner and to obtain excellent durability by using the resultant product of reaction between a silane coupling agent having an isocyanate group and specific compds. having a functional group reactive with said isocyanate group as a coating layer. CONSTITUTION:A coating layer is formed on a carrier by the resultant product of reaction between a silane coupling agent having an isocyanate group and 1 or >=2 kinds of compds. among ( I ) a compd. contg. a hydroxyl group having >=100mol.wt., (II) an amine compd. having >=100mol.wt., and (III) a compd. contg. a carboxyl group having >=100mol.wt. having the functional group reactive with said agent. The carrier material subjected to the surface coating in such a way is further coated with a polymer such as, for example, a methyl methacrylate/styrene copolymer, by which the carrier material having high volume reisistivity is obtd. Such carrier material improves the electrostatic charging stability of the toner and has excellent durability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic carrier material. More specifically, the present invention relates to an electrophotographic carrier material with improved durability and surface chargeability.

Conventionally, a cascade development method and a magnetic brush development method are known as methods for thermally developing an electrostatic latent image using a toner.

In both of these methods, a two-component developer is used, and this two-component developer consists of a mixture of toner particles with a particle size of 10-odd μm and carrier particles with a particle size of about 25 μm to about 200 μm, and these Particle contact retains the toner particles to the carrier particle surface. When this developer comes into contact with the electrostatic latent image on the photoconductor, the toner particles are attracted to form an image. It must have the correct electrostatic properties and magnitude of charge so that it is attracted to the target.

As a carrier for electrophotography (currently 4, diameter approximately 25μ77
Granules of iron, ferrite, steel, glass, etc. from 2 to about 2001 tm are commonly used. When these granular particles are used in their original form as a carrier, they tend to have the following drawbacks. That is, (1) the volume resistance of the carrier is low, and normal images cannot be obtained during copying.

(11) Due to the mechanical collision between the carrier and the toner over a long period of time, the thermoplastic resin, which is the main component of the toner, adheres to the surface of the carrier and forms a film.

For this reason, the frictional charging force t of the toner becomes non-uniform, making it impossible to obtain a copy with a good image.

(iii) In a high humidity environment (2S), moisture absorption on the surface of the carrier produces a tea scoop with a charge similar to (11N).

lv) In the case of iron or steel (d), the surface is oxidized by moisture and oxygen in the air, and the surface characteristics are delicate (it becomes two-component).

- Therefore, in order to eliminate such defects, methods of surface treatment of carriers have been proposed, and among these methods, coating the carrier particles with a polymer such as methyl methacrylate/styrene copolymer is often carried out. There is.

g. As for the covering method, it seems that the method generally employed is to spray the polymer solution onto the carrier particles in a fluidized bed and dry it. Also, a career? It has also been proposed to carry out suspension polymerization using a system containing a monomer as a core (a method of coating the carrier particles with a second layer). , epoxy resins and fluoropolymers (
4.9-51950), alkoxyvinylsilane compound and acrylic ester or styrene co-b [
There are combinations (Japanese Patent Laid-Open No. 50-147947), etc.

By employing such a polymer ah
When used in a barrel, the polymer detaches from the carrier surface, and even a polymer-coated carrier cannot be said to be a carrier material with excellent durability.

In view of the above-mentioned current situation regarding carrier materials, the inventors have conducted intensive research and found that a carrier material whose surface layer is entirely coated with 2 tons of a specific compound enables toner charging stability and is also excellent in durability. They discovered this and completed the present invention. That is, the present invention provides a silane coupling agent having an incyanato group, and a hydroxyl group-containing compound having a molecular weight of 100 or more (1) to (Ill) below, having a functional group capable of reacting with the incyanato group. 11) Amine compound with a molecular weight of 100 or more and (2)
The present invention provides a carrier material having a layer coated with a reaction product with one or more compounds selected from the group consisting of carboxyl group-containing compounds having a molecular weight of 100 or more.

The isocyanate group-containing silane coupling agent used in the present invention (C21(50)
38 i'C31-I 6NHCONI-IC6Ih
2NCO(Cl-130) 3S i C3I-16N
l-IC2H4NI-(C0NHC61-112N C
0(CH30)2Si C3H6NHC2H4NHC
ONI(C61-11□NCO■ (C2H3O)3 d 1C3I-I6NC2H4NH
C6H□2NCOCH2CH2011 etc.7 can be opened.

The hydroxyl group-containing compounds with a molecular weight of 100 or more, the amine compounds with a molecular weight of 100 or more, and the carboxyl group-containing compounds with a molecular weight of 100 or more according to the present invention are compounds other than compounds that do not substantially react with the silane coupling agent due to steric hindrance or the like. Although there are no particular restrictions on the compounds, seven representative compound groups and specific compound names are listed for each.

(1) Hydroxyl group-containing compounds with a molecular weight of 100 or more (compound group) - Higher alcohols having 8 to 32 carbon atoms - General formula (RO)lP'0' (OH) 3-4 (wherein, R is an alkyl group or alkenyl 1 or 15 or 2).

・General formula (RO(AO)n)6 PIO(OH)3g(
In the formula, R represents 7 alkyl or alkenyl groups, A represents 7 alkylene groups having 2 to 4 carbon atoms, and β is 1 or 15
or 2, and Ill'l: a phosphoric acid ester represented by 9, which represents an integer from 1 to 30.

・General formula (RCOO(AO)n″JIPO(OH)3-
6 (wherein R, A, l, and n have the same meanings as above).

・Fatty acid partial ester of polyhydric alcohol.

- A pomopolymer or copolymer consisting of a monomer component (having two copolymerizable double bonds and seven hydroxyl groups) in the molecule.

- Monomer component with a copolymerizable double bond and hydroxyl group in the molecule? Copolymers containing 0 Specific compound names> Rau IJ alcohol, myristyl alcohol, balmitoyl alcohol, stearyl alcohol, monododecyl phosphate, didodecyl phosphate, sesquidodecyl phosphate, sesquipropyl phosphate, sesquidodecyl polyoxyethylene (3 mole addition) phosphate, mono-ophtathecylpolyoxyethylene (5 mole addition) bosphate, sesquidotecylpolyoxypropylene (9 mole addition) phosphate, (C11H25COO(CH2CH20)10)IJ
' P O (OH) 1. s, C17l-135COO
(CH2Cl-120)Is PO(01-1)2
,L C3H11COO(CH2CH20)2)2
P O(OH), polyhydroxyethyl methacrylate, copolymer of hydroxyethyl methacrylate and methyl azilylate, etc. .

(II) Amine compound with a molecular weight of 100 or more (R1R
', R represents an alkyl group) Primary amine, secondary amine or tertiary amine/polyalkylene polyamine <Specific compound name> Stearylamine, dihexadecylamine tridecylamine, diethylenetriamine, etc. 011) Molecular weight 100 The above carboxyl group-containing compounds (compound group) - Higher fatty acids having 8 to 32 carbon atoms.

・Homopolymer consisting of vinyl monomer component having carboxyl group ・Hinyl monomer component having carboxyl group? A compound whose molecule end is a carboxyl group obtained from 1 mole of copolymer diol and 2 moles of dicarphonic acid (specific compound name): caproic acid, myristic acid, stearic acid, polymethacrylic acid, methacrylic acid and lauryl methacrylate Copolymers, esters whose molecular terminals are carboxyl groups obtained by esterification reaction of 1 mole of ethylene glycol and 2 moles of adipic acid, etc.

In the present invention, the method for obtaining the carrier material 7 coated with the reaction product (2) of the incyanate group-containing silane coupling agent and the compound selected from (1) to θω is not particularly limited; The method shown below is exemplified.

b) The carrier particles (1) are first heat-treated with the incyanate group-containing silane coupling agent (11) in an inert organic solvent, and then one or more selected from the group consisting of the above (1) to G11). A method of heat treating compound G11)7.

(1) and (11) and GiD in an inert organic solvent
'! rMethod of batch mixing and heat treatment.

c) First, the above (1]) and (iii) in an inert organic solvent.
2. A method of reacting, followed by (1) addition and heat treatment.

The amount of the incyanate group-containing silane camping agent according to the present invention is 01 to 5% by weight based on the carrier particles.
The amount is about 0.5 to 15% by weight, preferably 0.5 to 15% by weight. Further, 1 selected from B-r consisting of the above (I) to q11)
The appropriate amount of the species or two or more compounds to be used is 2 to 4 times the amount (by weight) of the incyanate group-containing silane coupling agent.

Examples of inert heating media that can be used to treat the carrier particles include benzene, toluene, xylene, methyl ethyl ketone, methyl imbutyl ketone, ethyl ketone, ethyl ketone, chlorhexafluorine, and the like. The use of common carriers is not particularly limited, and the viscosity when the reactants are charged is adjusted to an appropriate level (it is okay to adjust the viscosity slightly). Particles commonly used as conventional carriers can be used, such as steel, glass, sand, etc.

In the present invention (2), a reaction product of a silane coupling agent having an isocyanate group and a compound selected from the group consisting of (1) to (III) above and having a functional group capable of reacting with the isocyanate group. It is important to coat the surface of the carrier particles such as iron powder with
Even if the carrier material is coated with a compound that cannot react with the 1.1 group, it is not possible to obtain a carrier material with satisfactory performance.

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Nas-
s, % flow side and parts in comparative examples (means parts by weight).

(Example 1) 1 tube flask C2 with cooling tongue, iron particles (Japanese iron powder (I
EF-250) 100 parts, l-luene 300
Part, isoneanate group-containing 7 rankanobbling agent (C2HsQ)3slc3116NHcOc6H12
3 parts of NcO"e 1 m oj-stearyl alcohol was added and stirred with IWI for 2 hours at 80'C. Thereafter, the iron particles were washed with a large amount of toluene and then dried.

Next, the surface-treated iron particles are coated with methylmethacrylate (MMA)/styrene (Si) copolymer (copolymerization molar ratio MMA/5t=50/so, molecular weight approximately 200,000) to form a carrier material. And so. When coating, use a fluidized bed coating tester (manufactured by Fuji Sangyo ■). Using. Further, the copolymer was used in the form of a toluene solution with a solid content of 5%.

Next, 95 parts of the carrier material and toner (styrene (St
)/butyl acrylate 1-(BA) copolymer, copolymerization molar ratio St/BA2 85. /15, molecular weight approximately 100,002 as the main ingredient, and a small amount of carphone black? (including) 51Y13
An electrophotographic developer was prepared by mixing the two.

Evaluation of toner charge stability (TBC stability)〉2 rolls of polyester film are constant Ae Toner charge amount test consisting of a tram and magnetic plan type developing unit. Prepare and turn the magnetic flan 7 times. Toner after 8 hours of rotation and before rotation (hereinafter referred to as initial stage)
Toner -)-? Collect IS and measure the amount of charge (TEC)
? Measured using Blow-off Test 5 (manufactured by Higashihara Shibaura Gunki ■).

The rate of change in TEC after 8 hours of rotation with respect to the initial '1''EC is calculated and expressed as TECEC stability -1 to 5 values.

The correspondence between numerical values and rate of change is as follows.

Numerical value Change rate (support) 5 0~20 4 21~40 3 41~60 2 61~80 1 81~100 The larger the value, the better the TEC stability.

(Evaluation of TEC distribution stability) The TEC distribution of the toner used in the above-mentioned <TEC stability evaluation> was measured using the toner particle characteristic measuring device described in 1986-212442. I'm out of tune.8
Comparing the toner distribution pattern after time rotation with the initial toner distribution pattern, TEC distribution stability after 8 hours rotation 71
Expressed as a numerical value of ~3. The meaning of number 1 is as follows.

Numerical value Meaning 3 - The TEC distribution pattern after 8 hours is the same as that at the initial stage, and the TEC distribution stability is extremely good.

2. The TEC distribution pattern after 8 hours is slightly broader than the initial one, and the TEC distribution stability is moderate.

1. The TEC distribution pattern after 8 hours is broader than that at the initial stage, and T I > C distribution stability is poor.

The results of the evaluation of TEC stability and TEC distribution stability are shown in Table 1.

(Example 2) Surface-treated iron particles were obtained in the same manner as in Example 1, except that stearylamine 3 was used instead of the stearyl alcohol used in Example 1. And this iron particle? , was coated with the methyl methacrylate/styrene copolymer-C used in Example 1, and used as a carrier material. Hereinafter, an electrophotographic developer was prepared according to the method of Example 1, and the TEC stability and TE of the developer were determined in the same manner as in Example 1.
C distribution stability was evaluated. These results are shown in Table-1.

(Example 3) In the same manner as in Example 1 except that 3 parts of dihexatecylamine was used instead of the stearyl alcohol used in Example 1, iron particles 7 were obtained. Furthermore, these iron particles were coated with the methyl methacrylate/styrene copolymer used in Example 1 to form a carrier. Hereinafter, an electrophotographic developer 7 was prepared according to the method of Example 1, and the developed Regarding the agent, TEC stability was achieved using the method of Examples 1 and 1^''.
The stability of L and 'l'EC distribution was evaluated.These results are shown in Table-1.

? EXAMPLE Surface-treated iron particles were obtained in the same manner as in Example 1, except that 73 parts of sesquihexadecyl phosphate was used instead of the stearyl alcohol used in Example 1. The iron particles were coated with the methyl methacrylate/styrene copolymer used in Example 1 to serve as a carrier material. Hereinafter, electrophotographic developer 7 was prepared according to the method of Example 1,
The developer was evaluated for TEC stability and TEC distribution stability in the same manner as in Example 1. These results are shown in Table 1.
Shown below.

(Example 5) 1 liter of stearyl alcohol used in Example 1)
Surface-treated iron particles were obtained in the same manner as in Example 1, except that 3 parts of monododecyl polyoxyethylene (added by 5 moles) was used for (+). Further, the iron particles were coated with the methyl methacrylate/styrene copolymer used in Example 1 to form a carrier material. Hereinafter, an electrophotographic developer 7 was prepared according to the method of Example 1, and the TEC stability and TEC distribution stability of the developer were evaluated in the same manner as in Example 1. These results are shown in Table-1.

(Example 6) C niferite particles (
C manufactured by DM S5eward Man', CO.
B-100) and using 100 parts of I'nie (Co H25Coo (CH2
C1-I20) 10)□,s PO(OH)1.
5' Same as in Example 1 except that all three parts were used (2) Surface-treated iron particles were obtained. A copolymer was coated to prepare a carrier material.Hereinafter, an electrophotographic developer 7 was prepared according to the method of Example 1 (2), and TE was applied to the developer in the same manner as in Example 1.
Evaluation of C stability and TECEC distribution stability. These results (r:1Table-1(-) are shown.

(Example 7) Iron particles 2 used in Example 1 were placed in a 4-nozzle flask with a condenser tube.
100 parts of toluene, 500 parts of toluene, styrene (St)/methyl methacrylate (MMA)/hydroxyethyl acrylate (0-i BA) copolymer (copolymerization molar ratio St/
3 parts of λ4MA/HE A=60/20/20, molecular weight 25,000) and surface-treated iron particles in the same manner as in Example 1. Obtained.

Furthermore, these iron particles were coated with the methyl methacrylate/styrene copolymer used in Example 1 to serve as a carrier material. Hereinafter, an electrophotographic developer was prepared according to the method of Example 1, and the The TEC stability and 'I'J,>C distribution stability of the developer were evaluated in the same manner as in Example 1.The results are shown in Table 1.

(Example 8) Instead of the stearic acid used in Example 1, methacrylic acid (MA)/lauryl methacrylate (LMA) copolymer (copolymerization molar ratio 'fvl A / LM A -20)
Surface-treated iron particles were obtained in the same manner as in Example 1, except that 73 parts of the reaction mixture were used and the reaction conditions were 'Y90''C for 3 hours.

Further, the iron particles +7 were coated with the methyl methacrylate/styrene copolymer used in Example 1 to form a carrier material. Hereinafter, the method of Example 1 (secondary method) will be described below.
Prepare the developer (with two 'I' in the same way as in Example 1)
Evaluation of EC stability and TECEC distribution stability. These results are shown in Table-1.

(Comparative Example 1) Electrophotographic developer 2 was prepared according to the method of Example 1 using the iron particles used in Example 1 as a carrier material without any treatment or coating. The developer was evaluated for TEC stability and TECEC distribution stability using the same method as in Example 1. These results are shown in Table 1.

(Comparative Example 2) The iron particles 7 used in Example 1 were coated with the methyl acrylate/styrene copolymer used in Example 1 as a carrier material without surface treatment, and electron particles were coated according to the method of Example 1. I made some photo developer.

The developer was evaluated for T EC stability and 'J' EC distribution stability 7 in the same manner as in Example 1. These results are shown in Table-1.

(Comparative Example 3) Iron particles 1 used in Example 1 were placed in a 4-tube flask with a cooling tube.
007? l! ,,300 parts of toluene, 1 part of the silane coupling agent used in Example 1? Then, according to the method of Example 1, iron particles coated only with the silane coupling agent were obtained. Furthermore, the methyl methacrylate/styrene copolymer used on the actual flow side 1 was coated with the iron particles to form a carrier material, and an electrophotographic developer was prepared according to the method of Example 1. TE in the same manner as in Example 1.
Evaluation of C stability and TECEC distribution stability. The results are shown in Table-1.

(Comparative Example 4) Iron particles 1 used in Example 1 were placed in a 4-tube flask with a cooling tube.
00 and 13, 500 parts of toluene, 1 part of the 7 run force knobling agent used in Example 1, and 3 parts of polymethyl methacrylate (molecular weight about 100,000), which is a compound that cannot react with the silane coupling agent, Thereafter, according to the method of Example 1, iron particles coated with a silica/coupling agent and polymethyl methacrylate were obtained. Further, the methyl methacrylate/styrene copolymer used in all of the iron particles in Example 1 was made into a carrier material, and an electrophotographic developer 7 was prepared in accordance with the method of Example 1. The developer was evaluated for TEC stability and TECEC distribution stability using the same method as in Example 1. These results are shown in Table-1.

Claims (1)

[Claims] 1. A silane coupling agent having an isocyanate group and a functional group capable of reacting with the inocyanate group? The following (1) to 011), (1) a hydroxyl group-containing compound (II) with a molecular weight of 100 or more, an amine compound with a molecular weight of 100 or more, and (
III) A layer coated with a reaction product with one or more compounds selected from the group consisting of carboxyl group-containing compounds having a molecular weight of 100 or more? Carrier material for electrophotography with special features