JP2601782B2 - Conductive polyurethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller for controlling an electrostatically contacting object such as a toner conveying roller, a charging roller, a developing roller, a transfer roller and a cleaning roller in a printer for electrophotography and electrostatic recording. The present invention relates to a conductive polyurethane foam suitable for use as a material.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic process in which toner prepared in a toner cartridge is supplied to a photoreceptor on which an electrostatic latent image is formed, and is transferred and fixed on paper, generally includes charging, exposure, development, It consists of transfer, fixing, and static elimination mechanisms, and each mechanism uses various rollers for precisely controlling static electricity. In recent years, the required characteristics of the roller materials have become increasingly severe. In particular, the rollers used in the developing mechanism including the toner conveying roller, the charging roller, the developing roller, the transfer roller, and the roller used in the cleaning mechanism are electrically conductive materials of the rollers for electrically controlling the contacted object. It is required that the conductivity does not change significantly even when environmental conditions change. For example, practically 5 ° C, 3
In an environment from 0% relative humidity to 30 ° C. and 85% relative humidity, the change in resistance value is within one digit, for example, 1 × 10 ⁶ Ω · cm to
1 × 10 ⁷ Ω · cm or 1 × 10 ⁸ Ω · cm to 1 × 10 ⁹ Ω
・ It is required to be controlled in the cm range. In addition, these rollers are made of flexible polyurethane foam as a material to prevent damage to the partner due to contact with precision parts such as the photosensitive drum, or to increase the contact area of the rollers to ensure grip. But
In order to control static electricity in a fine region, the polyurethane foam is required to have a small cell size. A conventional example of such a conductive polyurethane foam as a roller material is a foam obtained by blending a conductive carbon in a mixture of a polyol, an isocyanate, a catalyst, and a foaming agent such as water or chlorofluorocarbon. Known are methods obtained by adding an ionic antistatic agent in the same manner as in Examples 1 and 2, and those obtained by impregnating a carbon paint or the like after forming a polyurethane foam.

[0003]

[SUMMARY OF THE INVENTION In conventional method, increase the conductivity (for example, the following volume resistivity 1 × 10 ⁶ Ω · cm Ah
Or 1 × 10 ⁹ Ω · cm or less ), the amount of added carbon increases, resulting in an increase in the viscosity of the system, resulting in insufficient mixing with other components, and the resulting conductive polyurethane foam A dense and uniform cell cannot be obtained, and the conductivity is not less than 1 × 10 ⁶ Ω · cm or 1 × 10 ⁸ Ω ·
In order to control the conductivity to more than cm , the conductivity was extremely changed by a delicate amount of added carbon, so that the conductivity could not be accurately controlled. In addition, the environment-dependent conductivity (resistance) of the product is large. In the method, the conductivity (resistance value) has a large environmental dependency. The method requires a relatively large cell structure to impregnate the carbon dispersion, and if the cells are fine, the carbon particles do not penetrate into the foam (the foam acts as a filter) and the conductivity is low. Becomes uneven.

[0004] The present invention has been made in view of the above circumstances, and provides a conductive polyurethane foam having dense and uniform cells and having relatively stable conductivity with respect to environmental changes. The purpose is to:

[0005]

In order to achieve the above-mentioned object, the present invention comprises mixing and dispersing a conductivity-imparting substance by an electron conduction mechanism and a conductivity-imparting substance by an ionic conduction mechanism in a composition material constituting a polyurethane foam. The mixture
The foam is formed by mechanical stirring with an inert gas .

[0006]

The conductive polyurethane foam according to the present invention uses ionic conductivity in combination, so that a polyurethane foam having a low resistance value can be obtained even with a small amount of conductive fine powder such as carbon, and a low viscosity during foaming. And a conductive polyurethane foam having a fine and uniform cell diameter can be obtained, and the environment is less dependent within the range of 1 × 10 ¹¹ Ω · cm to 1 × 10 ⁶ Ω · cm (5 ° C. × 30% relative humidity— 30 ° C x 85%
1 digit in volume resistivity under practical conditions of relative humidity, for example, 1 ×
(A range of 10 ⁸ Ω · cm to 1 × 10 ⁹ Ω · cm) A conductive polyurethane foam is obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.
As a resin constituting the polyurethane foam, a mixture of a polyhydroxyl compound and an organic polyisocyanate compound, a catalyst, a foam stabilizer and other additives is used. After compounding and dispersing a conductivity imparting substance by an ion conduction mechanism such as lithium, and dispersing the inert gas uniformly throughout the mixture by mechanical stirring to form a stable foam, the foam is thermally cured. Let me know.

The polyhydroxyl compounds include polyols used in the production of general flexible urethane foams and urethane elastomers, that is, polyether polyols and polyester polyols having a terminal hydroxyl group, and polyether polyester polyols which are copolymers of both. Further, general polyols such as a so-called polymer polyol obtained by polymerizing an ethylenically unsaturated monomer in a polyol can be used. As the polyisocyanate compound, a polyisocyanate generally used for producing a flexible urethane foam or a urethane elastomer can be used. That is, tolylene diisocyanate (TD1) crude TD1, 4,4′-diphenylmethane diisocyanate (MD1), crude MD1, aliphatic polyisocyanate having 2 to 18 carbon atoms, aliphatic polyisocyanate having 4 to 15 carbon atoms, and 8 carbon atoms To 15 aromatic polyisocyanates and mixtures or modified products of these polyisocyanates, such as prepolymers obtained by partially reacting with polyols. As a catalyst, a general organometallic compound,
For example, dibutyltin dilaurate, tin octylate, octylzinc, sodium acetate, etc., alkoxides and phenoxides of alkali and alkaline earth metals, tertiary amines, for example, triethylamine, triethyldiamine, N-methylmorpholine, dimethylaminomethylphenol, etc.
And quaternary ammonium salts, imidazoles can be mentioned <br/> is Ru. Similarly, nickel acetylacetonate, nickel diacetylacetonate, etc. shown in JP-B-53-8735 can be used. As the foam stabilizer, a known foam stabilizer used for foaming a polyurethane foam can be used, and there is no particular limitation. In addition, as other additives used in the present invention, known pigments, dyes, organic and inorganic fillers and the like added at the time of foaming the urethane foam can be used as necessary.

[0009] As the conductivity-imparting substance by the electron conduction mechanism, there is a powder of a substance having an electron-conductive property.
Or a fibrous substance such as common conductive carbon, graphite-based powder, or a single fiber thereof,
Conductive metal powders such as copper, nickel and silver or fibrous substances such as them, metal oxides such as tin oxide, titanium oxide and isodium oxide, or various fillers are subjected to metal plating to impart conductivity. Among the substances, there are organic conductive fine powders such as polyacetylene, polypyrrole, and polyacetylene.

Further, as conductivity-imparting substance by ionic conduction _{mechanism, LiCF 3 SO 3, Na C} lO 4, Li C
10 ₄ , LiAsF ₆ , LiBF ₄ , NaSCN, KS
CN, Li ^+, such as NaCl, Na ^+, K ⁺ etc. periodic table Group 1 metal salts or NH ₄ ⁺ electrolytes such salts, and also,
Ca (C lO _{4) 2} and the like Ca ^++, the periodic table Group II metal salt or its like and 1.4 butane diol Ba ⁺⁺ or the like, ethylene glycol, polyethylene glycol, propylene glycol, polyethylene glycol, and the like multi Complexes such as polyhydric alcohols and derivatives thereof, and complexes with monools such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether are exemplified.

Example 1 Polyether polyol (Exenol 828 of Asahi Glass Co., Ltd.) (OH value: 33) having a molecular weight of 5,000 by adding propylene oxide and ethylene oxide to glycerin, 100 parts Urethane-modified MD1 (Sumitomo Bayer Urethane) Co., Ltd. of Sumidur PF) NCO% = 23% 17.5 parts of 1.4-butanediol 1.0 part of silicon surfactant (Nippon Unica stock company made L-520) 1.5 parts of dibutyltin dilaurate 0.01 parts conductive carbon (electrochemical Industries stock Company Denka carbon) 1-2 parts of ion conductive material (Akishima chemical industry stock Company Ltd. MP-100-A) Li C lO 4, CH 3 OCH 2 CH 2 OCH 2 the CH ₂ OH complexes 0.5-1 parts which like placed in a plastic container of 1 liter household It was stirred for 2 minutes to obtain a foam having fine uniform cells with vertical machines. The foam was poured into a mold having a size of 100 mm × 100 mm × 50 mm in depth, heated at 140 ° C. for 7 minutes, cured, sliced, and examined for cell diameter, conductivity and the like. The resulting foam had a density of 0.52 g / cm ³ and a cell diameter of 200 μm or less.
The volume resistance value of a sheet with a uniform cell below and sliced to a thickness of 2 mm was measured by Yokogawa Hewlett-Packard High Re
The measurement was performed according to JIS-K6911 using sistance Meter 4329A and 16008A resistive cell. Conductive carbon 1 part of those the code A in the graph shown in Example 1 of FIG. 1, a complex of _{Li C l O 4 (MP-} 100-A)
And 0.5 parts of conductive carbon 2
Part, Li C l O ₄ complexes (MP-100-A) are those containing 1 part. Those indicated by reference signs C to E are only the addition of carbon, and contain 0.5 part, 1 part, and 2 parts, respectively. As a result of examining the environmental dependence of the conductivity, FIG.
As shown in (1), the addition of carbon alone (symbols C to E) depends on the environment, but uses a LiClO ₄ complex together (symbols A and C ).
B) By doing so, the environmental dependency of conductivity could be reduced. The only Li C lO ₄ can have a low resistance complex combination than carbon, (likely decrease the viscosity of the system was foamed) substantially it was able to reduce the amount of carbon to obtain the same resistance material. Further, using the conductive polyurethane foam obtained in Example 1, a roller having a structure as shown in FIG. 4 was prepared and used as a transfer roller. As a result, a uniform image was obtained. Also, when used as a charging roller, a good image was obtained. In FIG. 4, reference numeral 1 denotes a conductive polyurethane foam, and reference numeral 2 denotes a metal shaft.

Comparative Example 1 A conductive polyurethane foam obtained by foaming in the same manner as in Example 1 except that only 0.5 to 2 parts of carbon was added without adding the LiClO ₄ complex, and the density was 0.52 g / cm ³ . Especially,
The one containing 2 parts of carbon was coarse, having an average cell system of 500 μm, and all had a large environmental dependency on conductivity.

[0013] [Example 2] polyol (Asahi Glass stock company made EXCENOL 828, OH value 33) 100 parts of the urethane-modified MD1 (Sumitomo Bayer Urethane Co., Ltd. Sumidur PF) NCO% = 23% 25.0 parts 1.4 butane diol 2.5 parts silicone surfactant (Nippon Unicar stock Company Ltd. L-520) 1.5 part of dibutyltin dilaurate 0.01 part graphite powder (electron conductive substance) (Nippon graphite Industries stock Company Ltd. AUP) 10 to 60 parts (ion conductive material) (Akishima chemical industry stock Company Ltd. MP-100-E) Ca ( C lO 4) complex of _{2 CH 3 OCH 2 CH 2 OCH} 2 CH 2 OH ( diethylene glycol monomethyl ether) 1 ２2 parts The above composition was foamed in the same manner as in Example 1 and its conductivity (volume resistance) was measured. Although the case of adding only graphite there is no environmental dependence on a specific resistance (30 parts based graphite), it can not be obtained with less environmental dependence of low resistance yet with graphite alone system (Comparative Example). The symbol F in the graph of FIG. 2 represents 30 parts of graphite fine powder, Ca ( C
1 part of the complex (MP-100-E) of 1O ₄ ) ₂ , and the symbol G includes 60 parts and 2 parts, respectively.
Symbols H to K indicate only addition of graphite fine powder, and contain 10 parts, 15 parts, 30 parts, and 60 parts, respectively.
However, Ca (C lO ₄₎ with less environmental dependence was obtained at low <br/> resistance by ₂ complex combination (Example).

[0014] Comparative Example 2 Example 1 with a conductive only foam cells was added foaming a complex of Li C lO ₄ without adding carbon fine good although foam was obtained conductive (volume resistivity) The dependence on the environment was large, and the tendency did not change even if the number of added parts was changed (FIG. 3). The symbol L in the graph of FIG. 3 indicates that no conductivity-imparting substance was added by the electron conduction mechanism and the ion conduction mechanism, and the symbol M was MP-1.
One containing only 0.5 part of 00-A, the symbol N is MP-10
Those containing 1.0 part of only 0-A are shown.

[0015]

As described above, the present invention has not only an electron conduction mechanism but also an ion conduction mechanism, and has relatively stable conductivity with respect to environmental changes. In addition, due to the mechanical stirring, the cells have fine and uniform cells.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between temperature, humidity and volume resistance of an example of the present invention and a comparative example.

FIG. 2 is a graph similar to that of FIG. 1 in which only graphite is inserted and an embodiment of the present invention.

FIG. 3 is a graph similar to FIG. 1 with an ion conduction mechanism in which only MP-100-A is inserted and in which nothing is inserted.

FIG. 4 is a perspective view of a roller.

Claims (1)

(57) [Claims] 1. A mixture obtained by mixing and dispersing a conductivity-imparting substance by an electron conduction mechanism and a conductivity-imparting substance by an ionic conduction mechanism in a composition material constituting a polyurethane foam.
A conductive polyurethane foam formed by foaming by mechanical stirring with an inert gas .