JP4487930B2 - Method for producing flexible polyurethane foam, method for producing conductive flexible polyurethane foam, conductive roll and method for producing the same - Google Patents

Description

  The present invention is a method for producing a flexible polyurethane foam, and in particular, all or part of a poly (oxypropylene) polyol as a polyol component by a mechanical froth method is a poly (oxytetramethylene) polyol (hereinafter referred to as PTMG-based polyol). A method for producing a PTMG-based flexible polyurethane foam, a method for producing a low-density / low-hardness flexible polyurethane foam, a method for producing a conductive polyurethane foam, a conductive roll and a method for producing the same, especially for electrophotographic devices The present invention relates to a conductive roll, such as a toner conveying roll, a charging roll, a developing roll, a transfer roll, and a cleaning roll, which can easily control an object to be contacted electrostatically, and a method for producing the same.

  A mechanical floss process is used to produce flexible polyurethane foam. This mechanical froth method is a method of obtaining an object product by mixing an inert gas together with an isocyanate liquid and a polyol liquid, enclosing bubbles in a reaction mixture in advance, and reacting and curing the mixture. . The flexible polyurethane foam obtained by the mechanical floss method is 1) water is not used as a foaming agent, so urea bonds are not basically generated, and it is tough and has high impact resilience. 2) The cell has fine texture, It has the features such as the same size. For this reason, it is used for various rolls such as copying machines, various pads, shoe soles, cosmetic puffs, carpets, packing, sealing materials, and the like.

  Various methods described in, for example, Patent Literature 1 and Patent Literature 2 have been proposed as a method for producing a flexible polyurethane foam by the mechanical floss method. In the method described in Patent Document 1, since no foam stabilizer is used, there is an advantage that there are few problems of bleeding in the obtained polyurethane foam. In addition, the method described in Patent Document 2 has an advantage that a polyurethane foam with little pin fall can be obtained because alcohol-modified silicone oil is used and centrifugal molding is performed.

  However, in the method described in Patent Document 1, the cell sizes of the polyurethane foam cells to be obtained are uneven and the hardness varies depending on the part. When such polyurethane foam is used for a paper feed roll, it is accurately supplied. There was a problem that paper could not be used. In addition, the method described in Patent Document 2 has a problem that the molded product becomes thin because of centrifugal molding, and is not suitable for molding a block shape or a thick product.

  In general, polyether polyurethane is superior in hydrolysis resistance, low temperature characteristics, impact resilience, and the like, but inferior in mechanical characteristics such as abrasion resistance and room temperature flexibility, compared to polyester polyurethane. In order to improve the mechanical properties and the like of the polyether-based polyurethane, it has been proposed to replace all or part of the PPG-based polyol as a polyol component with a PTMG-based polyol (see, for example, Patent Document 3).

  However, PTMG-based polyols are difficult to maintain bubbles in the reaction mixture in the production by the mechanical froth method, and the resulting flexible polyurethane foam has a very high density. Thus, when the density becomes very high, the hardness becomes too high, and it has been difficult to obtain one that can withstand use in a field requiring flexibility. Therefore, a method capable of producing a flexible polyurethane foam having excellent mechanical strength, resilience, low temperature characteristics, etc., which are the characteristics of PTMG-based polyols, is desired.

  In electrophotographic apparatuses such as copying machines, printers, facsimiles, etc., in each process of charging, toner layer formation, development, cleaning, paper feeding, and conveyance in the electrophotographic process, charging roller, toner supply roller, developing roller, transfer roller Various rollers made of an elastic material or a resin material such as a paper feed roller and a transport roller are used. Since the rollers used in this electrophotographic apparatus come into contact with precision parts such as a photosensitive drum, the precision parts are not damaged, the contact area is increased to ensure grip, and the environment changes. Performance such as having conductivity that does not vary greatly is required.

  As a material used for a roll for an electrophotographic apparatus, conventionally, various rubbers have been used. However, a material in which an elastic body layer on the outer periphery of a roller shaft is formed of polyurethane foam is widely used. In a roller formed of polyurethane foam, it is desired that the polyurethane foam layer has a uniform internal and surface structure, proper conductivity required for each member, and the like. In recent years, in order to precisely control static electricity, a polyurethane foam to which a conductivity imparting substance such as carbon or metal oxide is added has been proposed (for example, see Patent Document 4 and Patent Document 5).

  In Patent Document 4, an inert gas is mechanically agitated in a mixture obtained by mixing and dispersing a conductivity-imparting substance such as carbon and the like, and a conductivity-imparting substance such as lithium perchlorate. There has been proposed a conductive polyurethane foam obtained by mixing and dispersing in accordance with the above and foaming and curing. In addition, Patent Document 5 proposes an additive for producing conductive polyurethane containing lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane as an essential component.

A conductive roll using a flexible polyurethane foam used for an electrophotographic apparatus has a small change in conductivity due to environmental changes, has a stable conductivity, and satisfies all of the following (a) to (c). It is desirable to be a thing.
(B) Asker hardness is C5 ° to C80 °
(B) The electrical resistance value is 1 × 10 ⁴ to 1 × 10 ⁸ Ω
(C) The density of the flexible polyurethane foam is 0.1 to 0.8 g / cm ³

  However, the alkali metal salt of perchloric acid used in Patent Document 4 has problems in practical use due to insufficient solubility in polyol or heat generation. Moreover, it is unclear whether the roll using the conductive polyurethane foam described in Patent Document 5 satisfies all the above conditions (A) to (C), and is suitable as a roll for an electrophotographic apparatus. It was unclear if it was something. Accordingly, there is a demand for a conductive roll that has a small change in conductivity due to environmental changes, has a stable conductivity, and satisfies all of the above conditions (A) to (C).

  As a method for producing a polyurethane foam having desired conductivity, a method is also known in which conductive carbon black is mixed in advance in a foaming polyurethane raw material and the conductive carbon black is dispersed in a matrix resin. (See Patent Document 6). However, with this method, the viscosity of the compounded liquid increases as the amount of conductive carbon black added increases, foaming is not performed smoothly, huge bubbles are formed in the polyurethane foam, and the flow of the compounded liquid is increased. There was a problem that a void defect was caused due to the deterioration.

In order to solve this problem, Patent Document 6 proposes dispersing conductive carbon black in polyurethane foam using a dispersant. However, in this method, there is a problem in that the physical properties of the polyurethane foam are deteriorated and the conductive carbon black is poorly dispersed if the amount of the dispersant is not controlled. Therefore, there is a demand for a method for producing a conductive polyurethane foam having good moldability and conductivity, and having low conductivity temperature dependence without using unnecessary additives.
JP 2001-89547 A Japanese Patent Laid-Open No. 10-258437 JP 2000-347496 A JP-A-5-262907 JP 2002-146178 A JP 2003-98786 A

  In view of the above-described problems, the present invention is based on a method for producing a flexible polyurethane foam having both the characteristics of a PTMG-based foam and the characteristics of a mechanical floss method foam, and the conventional mechanical floss method described in Patent Document 1 and Patent Document 2 above. A method for producing a flexible polyurethane foam having a low hardness and a low density, and a method for producing a conductive polyurethane foam having good moldability and conductivity, and having a low conductivity temperature dependence, and environmental changes. It is an object of the present invention to provide a conductive roll having a small change in conductivity due to the above, having a stable conductivity, and satisfying all the above conditions (A) to (C) and a method for producing the same.

  The present invention has been found as a result of intensive studies in order to solve the above problems, and the method for producing a flexible polyurethane foam of the present invention is shown in the following (1) to (3).

(1) In a method for producing a flexible polyurethane foam in which a reaction mixture of an isocyanate liquid containing an inert gas and a polyol liquid is reacted in the presence of a catalyst and a surfactant, 50 mass of PTMG polyol is contained in the polyurethane foam. And a sorbitan fatty acid ester is used as a surfactant in an amount of 0.1 to 5% by mass based on the polyurethane foam.

(2) The isocyanate liquid contains an isocyanate group-terminated urethane prepolymer obtained by reacting diphenylmethane diisocyanate (MDI) and poly (oxytetramethylene) polyol. It is a manufacturing method.

(3) The manufacturing method according to (1) or (2) above, wherein the polyol liquid contains a PTMG-based polyol.

The process for producing a low hardness / low density flexible polyurethane foam according to the present invention comprises a polyurethane foam forming property in which an organic polyisocyanate (A), a polyol (B), a catalyst (C), and a foam stabilizer (D) are dispersed and mixed. In the method for producing a polyurethane foam, wherein the composition is further mixed and dispersed with an inert gas by mechanical stirring and then foam-cured.
The foam stabilizer (D) is a dimethylpolysiloxane-polyether polyol block copolymer,
Silicon content is 10-30% by mass,
The molecular weight distribution in the weight average molecular weight is 1,000 or more and less than 2,000: 30 to 40%, 2,000 or more and less than 4,000: 40 to 50%, 4,000 or more: 20 to 30%,
The mass ratio of a dimethylpolysiloxane part and a polyether polyol part is dimethylpolysiloxane part: polyether polyol part = 10: 90-30: 70, It is a manufacturing method of a polyurethane foam characterized by the above-mentioned.

  The process for producing a conductive polyurethane foam of the present invention comprises an isocyanate liquid (E) comprising an organic polyisocyanate (e), a polyol (f1), a catalyst (f2), a foam stabilizer (f3), and a conductive agent (f4). A method for producing a conductive polyurethane foam in which a polyol liquid (F) mixed in advance and an inert gas (G) are mixed and dispersed by mechanical stirring and then the mixed liquid is cured, and the conductive agent (f4) Is a process for producing a conductive polyurethane foam characterized by comprising vapor grown carbon fiber (f4-1) and carbon black (f4-2).

  In the method for producing a conductive polyurethane foam according to the present invention, the content of the conductive agent (f4) in the polyurethane foam is 1.8 to 3.6% by mass. Is the method.

  Furthermore, in the method for producing the conductive polyurethane foam of the present invention, the mass blending ratio of the vapor grown carbon fiber (f4-1) and the carbon black (f4-2) is (f4-1) / (f4-2) = 8. / 2 to 2/8. A method for producing a conductive polyurethane foam.

The conductive roll of the present invention is a conductive roll in which a polyurethane foam is formed around a conductive core material,
A polyurethane foam-forming composition in which the polyurethane foam is a dispersion-mixed organic polyisocyanate (H), polyol (I), catalyst (J), foam stabilizer (K), and conductivity-imparting substance (L), Furthermore, after mixing and dispersing the inert gas by mechanical stirring, it is foam cured.
The conductivity-imparting substance (L) includes an ionic conductive agent (L1) containing either one or both of potassium bis (trifluoromethanesulfonyl) imide and lithium bis (trifluoromethanesulfonyl) imide,
The conductive roll has an Asker hardness of C5 ° to C80 °, a resistance value of 1 × 10 ⁴ to 1 × 10 ⁸ Ω,
The density of the polyurethane foam is 0.1 to 0.8 g / cm ³ .

  By adopting such a polyurethane foam, as shown in the examples described later, the change in conductivity due to environmental changes is small, stable conductivity, and the range of Asker hardness and electrical resistance value is within the above range. An excellent conductive roll can be provided.

In addition, the measuring method and conditions of Asker hardness of an electroconductive roll, an electrical resistance value, and the density of a polyurethane foam are as follows.
<Conductive roll>
Shape of conductive roll Core material: Diameter 6 mm x Length 270 mm
Polyurethane foam: radial thickness 8mm x length 230mm
The core material had a shape that protruded 20 mm from both ends of the polyurethane foam.
<Asker hardness>
The Asker hardness tester C type was pressed against the surface of the conductive roll in which the polyurethane foam was formed around the core material, and the Asker hardness was measured. The Asker hardness was measured at five or more locations, and the average value was taken as the measured value. The measurement atmosphere was 23 ° C. × 55% RH.
<Electric resistance value>
The conductive roll is placed on an aluminum plate of 300 mm × 300 mm × 3 mm, electrodes are connected to the core material and the aluminum material protruding from the polyurethane foam, and a voltage of 1,000 V is applied between the electrodes, The electrical resistance value was measured. The electrical resistance value was measured five times or more by appropriately rotating the conductive roll, and the average value was taken as the measured value. The measurement atmosphere was 23 ° C. × 55% RH.
<Density>
A value obtained by subtracting the mass of the core material from the mass of the conductive roll was obtained and divided by the apparent volume of the polyurethane foam formed around the core material to obtain the density of the polyurethane foam.

In addition, the conductive roll of the present invention is a polyurethane foam molding in which organic polyisocyanate (H), polyol (I), catalyst (J), foam stabilizer (K), and conductivity-imparting substance (L) are dispersed and mixed. A method for producing a conductive roll in which a polyurethane foam formed by further mixing and dispersing an inert gas by mechanical stirring and then foaming and curing the conductive composition is formed around a conductive core material,
The conductivity imparting substance (L) contains an ionic conductive agent (L1) containing either one or both of potassium bis (trifluoromethanesulfonyl) imide and lithium bis (trifluoromethanesulfonyl) imide. It can obtain by the manufacturing method of a property roll.

  Moreover, in the manufacturing method of the electroconductive roll of this invention, the said electroconductivity imparting substance (L) is ionicity containing either one or both of potassium bis (trifluoromethanesulfonyl) imide or lithium bis (trifluoromethanesulfonyl) imide. Since the conductive agent (L1) is contained, the obtained conductive polyurethane foam has an ionic conduction mechanism due to the ionic conductive agent (L1), and the variation in conductivity due to the site is small.

  In the conductive polyurethane foam, the conductivity-imparting substance (L) may contain conductive carbon (L2).

  In general, since the ionic conductive agent (L1) contributes to improving the conductivity in a small amount, the resulting conductive polyurethane foam has a small variation in conductivity depending on the site, but has a large change in conductivity due to environmental changes. There is. On the other hand, the conductive carbon (L2) has a small change in conductivity due to environmental change, but it is necessary to increase the amount of addition in order to make the polyurethane foam exhibit practical conductivity. However, the conductive carbon (L2) is a fine particle and is difficult to uniformly disperse inside the polyurethane foam. For this reason, the conductive polyurethane foam using conductive carbon (L2) tends to have a large variation in conductivity depending on the part. Therefore, by using the ionic conductive agent (L1) and the conductive carbon (L2) in combination, a uniform conductive polyurethane foam in which the change in conductivity due to environmental changes is small and the variation in conductivity due to the site is small. can get.

  The production method employed in the present invention comprises a polyurethane foam-forming composition in which organic polyisocyanate, polyol, catalyst, and foam stabilizer are dispersed and mixed, and further an inert gas is mixed and dispersed by mechanical stirring, followed by foaming. This is a method called mechanical flossing, which is hardened. Compared with methods using ordinary physical and chemical foaming agents, a homogeneous foam can be obtained, and conductive flexible polyurethane foam with the above-mentioned Asker hardness and density. Is easily obtained. Here, the physical foaming agent is a material that foams by a physical change from a liquid such as chlorofluorocarbon or hydrocarbon to a gas. In addition, the chemical foaming agent is a material that foams with a gas generated by a chemical reaction such as water.

  The flexible polyurethane foam, conductive flexible polyurethane foam and conductive roll production method of the present invention all use the mechanical floss method. Hereinafter, the manufacturing method of each form and roll will be described in detail by itemizing.

1. Manufacturing method of flexible polyurethane foam In the manufacturing method of the flexible polyurethane foam of this invention, an isocyanate liquid, a polyol liquid, a catalyst, and surfactant are used as a raw material. As the isocyanate liquid used in the present invention, MDI, carbodiimidized diphenylmethane diisocyanate (liquid MDI), polymeric MDI, tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), paraphenylene diisocyanate (PPDI), tetramethylxylylene diene Isocyanate (TMXDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), naphthalene diisocyanate (NDI), hydrogenated diphenylmethane diisocyanate (H ₁₂ MDI), hydrogenated xylylene diisocyanate (H ₆ XDI), cyclohexyl diisocyanate (CHDI) In addition, some of the isocyanate groups of these isocyanate group-containing compounds are urethane, Examples include uret, allophanate, carbodiimide, uretonimine, oxazolidone, amide, imide, isocyanurate, uretdione and the like. These may be used alone or in combination of two or more as required. In the present invention, MDI, liquid MDI, polymeric MDI, and these isocyanate group-terminated urethane prepolymers are preferred in consideration of the working environment at the time of producing the flexible polyurethane foam, the physical properties of the foam, and the like.

  The MDI and polymeric MDI will be described in more detail. MDI is 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 2,2'-diphenylmethane diisocyanate (2,2'-MDI) Are present in the form of a mixture of any three isomers in any proportion (in some cases, any single item).

  Polymeric MDI is a mixture of MDI and an MDI polynuclear mixture described later. The MDI polynuclear mixture exists in the form of a mixture of compounds having three or more benzene rings having an isocyanate group bonded in one molecule and having different degrees of condensation. Usually, it is not supplied in the form of an MDI-based multinuclear mixture alone, but in the form of a mixture with MDI, that is, polymeric MDI.

  In the first place, polymeric MDI is obtained by converting an amino group to an isocyanate group by phosgenation or the like of a condensation mixture (polyamine) obtained by the condensation reaction of aniline and formalin, and the product has a different degree of condensation from MDI. It is an MDI-based multinuclear mixture. The composition of MDI or polymeric MDI can be changed by changing the raw material composition ratio or reaction conditions during condensation, or by partially removing MDI by distillation. The MDI content of polymeric MDI and the isomer composition ratio of MDI can be determined from a calibration curve based on the area percentage of each peak obtained by gel permeation chromatography or gas chromatography.

  In the present invention, considering the working environment at the time of foam production, foam moldability, physical properties of the resulting polyurethane foam, etc., the MDI having a 4,4′-MDI content of 50 to 100% by mass, 4,4 ′ -Polymeric MDI containing MDI having an MDI content of 50 to 100% by mass, and these isocyanate group-terminated urethane prepolymers are preferred.

  The polyol liquid in the present invention is a mixture of a polymer polyol, a chain extender, a catalyst, a surfactant, and other additives as necessary.

  Examples of the polymer polyol include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols (hydrophobic polyols), animal and vegetable oil-based polyols having a number average molecular weight of 500 to 10,000 and a nominal average functional group number of 2 to 8. . These polymer polyol components may be used alone or in combination of two or more.

  Examples of polyether polyols include those obtained by addition polymerization of alkylene oxide using propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, or the like as a starting material.

  Polyester polyols include condensed polyester polyols obtained by condensation of dicarboxylic acids with diols and triols, lactone polyester polyols obtained by ring-opening polymerization of lactones based on diols and triols, and polyether polyols with lactones at the ends. Examples include polyols such as ester-modified polyols that have been ester-modified.

  Examples of the polycarbonate polyol include those obtained by a transesterification reaction between a low molecular polyol such as butanediol or hexanediol and a low molecular carbonate such as propylene carbonate or diethyl carbonate.

  Examples of the polyolefin polyol include polyisoprene polyol, polybutadiene polyol, and hydrogenated polybutadiene polyol.

  Examples of animal and vegetable oil-based polyols include silk fibron, castor oil-based polyols (including those obtained by dehydration and hydrogenation), and cellulose-based polyols.

  The present invention is applied to a method for producing a PTMG-based flexible polyurethane foam by a mechanical floss method. Here, the PTMG-based flexible polyurethane foam refers to a polyurethane foam containing 50% by mass or more of a PTMG-based polyol. In order to obtain a flexible polyurethane foam containing 50% by mass or more of a PTMG-based polyol, 1) a PTMG-based polyol is used for the polyol of the isocyanate group-terminated urethane prepolymer 2) a PTMG-based polyol is used for the polyol liquid 3) an isocyanate group-terminated Any method of using a PTMG-based polyol for both the urethane prepolymer and the polyol liquid can be employed.

  Examples of the chain extender include ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, tetramethylene ether glycol, polyethylene glycol and the like. These chain extenders may be used alone or in combination of two or more. In the present invention, 1,4-butanediol is preferred. This is because 1,4-butanediol has a primary hydroxyl group and thus has good reactivity, is liquid at room temperature, has excellent workability, and has an appropriate molecular weight, and has excellent mechanical strength. Is obtained.

  Examples of the catalyst used in the present invention include monoamines such as triethylamine and dimethylcyclohexylamine, diamines such as tetramethylethylenediamine, tetramethylpropanediamine, and tetramethylhexanediamine, pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, and tetramethyl. Triamines such as guanidine, triethylenediamine, dimethylpiperazine, methylethylpiperazine, cyclic amines such as methylmorpholine, dimethylaminoethylmorpholine, dimethylimidazole, dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxyethyl Alcohol amines such as piperazine and hydroxyethylmorpholine, bis (dimethyl) Aminoethyl) ether, ether amines such as ethylene glycol bis (dimethyl) aminopropyl ether, stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin Known catalysts such as marker metal, dioctyltin thiocarboxylate, phenylmercury propionate, and organometallic compounds such as phenylmercury octenoate can be used alone or in combination of two or more.

  The surfactant used in the present invention contains sorbitan fatty acid ester, which is an incomplete ester compound composed of saturated or unsaturated fatty acid as sorbitan by heating and dehydrating (intramolecular etherification) of sorbitol. Here, the incomplete ester compound means that all hydroxyl groups of sorbitan are not esterified. Saturated or unsaturated fatty acids having 10 to 30 carbon atoms are preferred because they have good compatibility with PTMG-based polyols and good foam stabilizing effects. Examples of the saturated or unsaturated fatty acid include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid and the like. In the present invention, the sorbitan fatty acid ester is preferably a liquid at room temperature in consideration of workability in blending with a polyol liquid. Moreover, since sorbitan fatty acid ester has a hydroxyl group, it reacts with an isocyanate group at the time of curing, and therefore does not bleed. A preferred hydroxyl value is 50 to 400 mgKOH / g, and a particularly preferred hydroxyl value is 180 to 360 mgKOH / g. Examples of such sorbitan fatty acid esters include sorbitan monolaurate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, sorbitan monopalmitate, and the like.

  In the present invention, other conventionally known additives can be used as necessary. Examples of the additives include antioxidants, ultraviolet absorbers, flame retardants, colorants, conductive agents, insulating agents, and light emitting agents. Agents, antibacterial agents, fragrances and the like.

  In order to produce PTMG-based flexible polyurethane foam using these raw materials, the isocyanate liquid and polyol liquid stored or prepared in separate containers are put into one mixing head, and an inert gas is mixed therein. The mixture is mixed so as to be homogeneous, and the mixed solution is poured on a conveyor with a formwork and a bottom paper and heated and cured, or the mixed solution is poured into a predetermined mold and heat cured. be able to. The foam obtained by this method becomes a polyurethane foam having uniform fine cells and moderate hardness.

  In this case, the isocyanate index (isocyanate group / active hydrogen group × 100) is preferably from 60 to 120, particularly preferably from 80 to 110. If the index is too low, the foam surface tends to be sticky. Also, if the index is too high, it may not fire, or it may fall into a flexible form.

The flexible polyurethane foam thus obtained has a density of 0.1 to 0.9 g / cm ³ and an Asker hardness C of 30 to 90 °, and becomes a uniform foam having fine cells.

2. Method for producing flexible polyurethane foam In the method for producing a low density / low hardness flexible polyurethane foam of the present invention, organic polyisocyanate (A), polyol (B), catalyst (C), and foam stabilizer (D) are used as raw materials. use.

  The organic polyisocyanate (A) used in the present invention can include those used in the isocyanate liquid described in the above item 1, and can be used alone or in combination of two or more as required. .

  In the present invention, the organic polyisocyanate (A) has an isocyanate content of 5 to 35% by mass and a viscosity at 25 ° C. of 2,000 mPa · s or less in consideration of workability and moldability. In particular, the isocyanate content is preferably 10 to 30% by mass, and the viscosity at 25 ° C. is preferably 1000 to 8000 mPa · s.

  Also in the present invention, considering the working environment at the time of foam production, formability of the foam, physical properties of the resulting polyurethane foam, etc., MDI having a 4,4′-MDI content of 50 to 100% by mass, 4,4 ′ -Polymeric MDI containing MDI having an MDI content of 50 to 100% by mass, and these isocyanate group-terminated urethane prepolymers are preferred.

  The polyol (B) used in the present invention comprises a polymer polyol and a chain extender, and examples of the polymer polyol include polyether polyol, polyester polyol, polycarbonate polyol, and hydrophobic polyol. As the polyether polyol, the polyether polyol described in the above item 1 can be used, and in particular, glycerin obtained by addition polymerization of ethylene oxide or ethylene oxide and propylene oxide is preferable. Examples of the polyester polyol, polycarbonate polyol, hydrophobic polyol, and chain extender include the polyols and chain extenders described in the above item 1. These polymer polyol components may be used alone or in combination of two or more.

  The above-described polymer polyol is preferably hydrophobic. This is because the water absorption of the resulting foam is small, and the change in the conductive environment is small. A more preferred polyol has a substantial average functional group number of 2 to 4, a number average molecular weight of 1,000 to 10,000 (particularly preferably 2,000 to 5,000) and an oxyethylene group content of 50% by mass or less. Poly (oxypropylene) polyol or poly (oxyethylene-oxypropylene) polyol. The poly (oxyethylene-oxypropylene) polyol includes, for example, a block copolymer type, a random copolymer type, or a polymer obtained by adding ethylene oxide to the terminal of the poly (oxypropylene) polyol. When the substantial average functional group number is too small or the number average molecular weight is too large, the hardness of the foam tends to be too low. When the substantial average functional group number is too large or the number average molecular weight is too small, the foam hardness tends to be too high.

  Examples of the catalyst (C) used in the present invention include the catalyst described in the above item 1. The foam stabilizer (D) used in the present invention is a dimethylpolysiloxane-polyether polyol block copolymer having a silicon content of 10 to 30% by mass and a molecular weight distribution in a weight average molecular weight of 1,000. 2,000 or less: 30 to 40%, 2,000 or more and less than 4,000: 40 to 50%, 4,000 or more: 20 to 30%, and the mass ratio of the dimethylpolysiloxane part to the polyether polyol part is dimethyl. Polysiloxane part: polyether polyol part = 10: 90 to 30:70.

  When the silicon content of the foam stabilizer (D) is out of the above range or when the mass ratio between the dimethylpolysiloxane part and the polyether polyol part is dimethylsiloxane rich, the resulting foam is difficult to take a fine cell structure. When the mass ratio of the dimethylpolysiloxane part and the polyether polyol part is rich in the polyether polyol, or when the molecular weight distribution is out of the above range, it is difficult to obtain a foam in which fine cells are uniformly dispersed or a low density foam.

The silicon content is measured by an ashing method, and specifically measured by the following procedure.
"Method for measuring silicon content"
(1) Weigh sample accurately into crucible.
(2) The crucible is heated to burn the contents.
(3) Weigh the residue (ash) remaining in the crucible.
(4) The silicon content is calculated according to the following formula.

The molecular weight distribution is measured by a gel permeation chromatography (GPC) method, and the measurement conditions are as follows.
"Molecular weight distribution measurement method"
Molecular weight distribution is evaluated by calculating the area% of each peak in the GPC chart. Apparatus: HLC-8220 manufactured by Tosoh Corporation
Column: TSKgel G3000H _XL x 2 + TSKgel G2000H _XL x 2 Fluid medium: THF (tetrahydrofuran)
Flow rate: 1 ml / min
Measurement temperature: 40 ° C
Detector: RI detector Injection volume: 100 μl
Weight average molecular weight: Calculated as a relative molecular weight with polystyrene Baseline: A line connecting the rising edge of the first peak and the end of the last peak in the GPC chart, not a line connecting the valleys and valleys of the peaks.

The mass ratio between the dimethylpolysiloxane part and the polyether polyol part can be determined by calculating by ¹ H-NMR measurement. The ¹ H-NMR measurement conditions in the present invention are as follows.
Model: Varian Unity 500 (FT-NMR)
Measurement frequency: 500 MHz

  The foam stabilizer (D) consists of oxyethylene groups and oxypropylene groups as repeating units in the polyether polyol portion, and the mass ratio of oxyethylene groups to oxypropylene groups is oxyethylene groups / oxypropylene groups. = 50 / 50-80 / 20 is preferable. This ratio is considered to be a ratio that imparts appropriate lipophilicity and hydrophilicity to the foam stabilizer (D) and exhibits the foam regulating action, that is, the performance as a surfactant to the maximum.

The ratio of the oxyethylene group and the oxypropylene group described above can be obtained by performing a Corish decomposition of the foam stabilizer and calculating the recovered product by ¹ H-NMR measurement.

  The present invention can also use other conventionally known additives as required, for example, antioxidants, ultraviolet absorbers, flame retardants, colorants, conductive agents, insulating agents, luminescent agents, antibacterial agents, and fragrances. Etc.

  In order to produce a flexible polyurethane foam using these raw materials, the polyisocyanate component, polyol component, catalyst, and other additions stored or prepared in separate containers are the same as described in the above item 1. Add the agent to one mixing head while mixing inert gas, mix it homogeneously, flow the mixture on a conveyor with a formwork and bottom paper, and heat and cure, or mix the mixture A method of casting in a predetermined mold or the like and curing by heating can be used. The foam obtained by such a method is a polyurethane foam having uniform fine cells and appropriate hardness. In addition, when a foaming agent is used, a cell will not become uniform.

  In this case, the isocyanate index (isocyanate group / active hydrogen group × 100) is preferably from 60 to 120, particularly preferably from 80 to 110. If the index is too low, the foam surface tends to be sticky. Moreover, when an index is too high, it may not harden | cure or it may become a foam with insufficient flexibility.

The flexible polyurethane foam thus obtained has a density of 0.2 to 0.9 g / cm ³ and an Asker hardness C of 80 or less, and becomes a uniform foam having fine cells.

3. Method for Producing Conductive Polyurethane Foam In the method for producing a conductive polyurethane foam of the present invention, an isocyanate liquid (E) comprising an organic polyisocyanate (e), a polyol (f1), a catalyst (f2), a foam stabilizer (f3) and A polyol liquid (F) in which a conductive agent (f4) is mixed in advance is used as a raw material.

  As organic polyisocyanate (e) used for this invention, what is used for the isocyanate liquid demonstrated by said 1st term can be mentioned. In consideration of the working environment at the time of foam production, the moldability of the foam, the physical properties of the resulting polyurethane foam, etc. Polymeric MDI containing MDI in an amount of 50 to 100% by weight, and these isocyanate group terminated urethane prepolymers are preferred.

  The polyol (f1) used in the present invention comprises a polymer polyol and a chain extender. Examples of the polymer polyol include polyether polyol, polyester polyol, polycarbonate polyol, and hydrophobic polyol. Examples of these polyols (f1) include those used in the polyol liquid described in the above item 1.

  The above-described polymer polyol has a substantial average functional group number of 2 to 4 and a number average molecular weight of 1,000 to 10,000 (particularly preferably 2,000 to 8,8) in consideration of the touch of the resulting flexible polyurethane foam. 000) is a poly (oxypropylene) polyol or poly (oxyethylene-oxypropylene) polyol having an oxyethylene group content of 50% by mass or less. The poly (oxyethylene-oxypropylene) polyol includes, for example, a block copolymer type, a random copolymer type, or a polymer obtained by adding ethylene oxide to the terminal of the poly (oxypropylene) polyol. When the substantial average functional group number is too small or the number average molecular weight is too large, the physical properties of the foam tend to be too small. When the substantial average functional group number is too large or the number average molecular weight is too small, the foam becomes hard and the touch tends to be poor.

  Examples of the chain extender and catalyst (f2) include the chain extender and catalyst described in the above item 1. As the foam stabilizer (f3), an organosilicon surfactant known in the art can be used. For example, L-520, L-540, L-5309, L-5366, manufactured by Nippon Unicar Company, Ltd. SZ-1306, Toray Dow Corning SH-193, SRX-274C, Goldschmidt B-4113, and the like.

  In the present invention, the conductive agent (f4) is composed of vapor grown carbon fiber (f4-1) and carbon black (f4-2). In this invention, 1.8-3.6 mass% is preferable, and, as for content of the electrically conductive agent (f4) in a polyurethane foam, Most preferably, it is 2.0-3.5 mass%. When there is too little conductive agent (f4), sufficient electroconductivity cannot be provided to a polyurethane foam. When the amount is too large, the viscosity of the foam liquid becomes too high, and voids and pinholes are easily generated in the obtained foam.

Vapor grown carbon fiber (f4-1) is easier to disperse in polyol as compared with other carbon-based conductive agents such as graphite and acetylene black, so that the viscosity increase of the foam liquid before the reaction is suppressed, It has the feature that voids, pinholes, etc. are less likely to occur. This vapor grown carbon fiber (f4-1) is, for example, produced by mixing a carrier gas heated to 700 to 1,600 ° C. with a raw material gas of carbon fiber preheated to 100 to 450 ° C. It can be obtained by sending it to the furnace. The preferred properties are a fiber diameter of 50 to 500 nm (particularly preferably 100 to 300 nm), an aspect ratio of 10 to 5,000 (particularly preferably 10 to 1,000), and a fiber length of 1 to 100 μm (particularly preferably 5). To 50 μm), the specific surface area is 1 to 100 m ² / g (particularly preferably 5 to 50 m ² / g), and the bulk specific gravity is 0.01 to 0.1 g / cm ³ (particularly preferably 0.02 to 0.08 g / g). cm ³ ).

Carbon black (f4-2) includes various types such as acetylene black, ketjen black, furnace black, thermal black, lamp black, channel black, gas black, disk black, etc. . In the present invention, it is easy to obtain a high-purity product, and acetylene black having high conductivity is preferable. This acetylene black is obtained by thermally decomposing acetylene gas, belongs to the middle of graphite and amorphous carbon, and is referred to as a three-dimensional chain structure (hereinafter referred to as “structure”) in which a large specific surface area and primary particles are connected. It is a high-purity carbon black that is less likely to be mixed with impurities. The preferred properties are an average particle size of 10 to 100 nm (particularly preferably 15 to 50 nm), a specific surface area of 1 to 200 m ² / g (particularly preferably 5 to 100 m ² / g), and a bulk specific gravity of 0.01 to 0. 0.1 g / cm ³ (particularly preferably 0.02 to 0.08 g / cm ³ ).

  The composition of the conductive agent (f4) is preferably vapor-grown carbon fiber (f4-1) / carbon black (f4-2) = 8/2 to 2/8 by mass ratio, particularly preferably 7/3 to 3 /. 7. When there are too many vapor grown carbon fibers (f4-2), electroconductivity becomes inadequate or the temperature dependence of electroconductivity becomes large. That is, when the content of the entire conductive material in the polyurethane foam is constant, the composition of the conductive agent is higher than that of the vapor-grown carbon fiber (f4-1) or carbon black (f4-2) alone. The carbon fiber (f4-1) / carbon black (f4-2) mixed system has higher conductivity and has lower temperature dependency.

  In the present invention, other conventionally known additives can be used as necessary, for example, antioxidants, ultraviolet absorbers, flame retardants, colorants, insulating materials, luminescent agents, antibacterial agents, fragrances and the like. Can be mentioned.

  In order to produce a conductive flexible polyurethane foam using these raw materials, a method similar to the method for producing a flexible polyurethane foam described in the above item 1 and item 2 can be used. Using the above raw materials, the polyisocyanate component, polyol component, catalyst, and other additives that have been stored or prepared in separate containers are introduced into one mixing head while mixing an inert gas, and homogeneous. The mixed solution is flowed on a conveyor with a formwork or bottom paper and heated and cured, or the mixed solution is poured into a predetermined mold and heat-cured. it can. The foam obtained by such a method is a polyurethane foam having uniform fine cells and appropriate hardness.

  In this case, the isocyanate index (isocyanate group / active hydrogen group × 100) is preferably from 60 to 120, particularly preferably from 80 to 110. If the index is too low, the foam surface tends to be sticky. Also, if the index is too high, it may not fire, or it may fall into a flexible form.

The conductive polyurethane foam thus obtained has a density of 0.1 to 0.9 g / cm ³ and becomes a uniform foam having fine cells. Moreover, the Asker hardness C in the roll in which the foam is formed around the shaft is 3 to 90 °.

4). Conductive roll and manufacturing method of conductive roll Small change in conductivity due to environmental change, stable conductivity, and small variation in conductivity due to site, even if it comes in contact with precision parts such as a photosensitive drum In the method for producing a conductive roll having a certain grip property without damaging, an organic isocyanate (H), a polyol (I), a catalyst (J), a foam stabilizer (K), and a conductivity imparting substance (L) are added. Used as a raw material.

  The organic polyisocyanate (H) used in the present invention is not particularly limited as long as it has two or more isocyanate groups in one molecule, and any of them can be used. As organic polyisocyanate (H), what is used for the isocyanate liquid demonstrated by the said 1st term can be used. These may be used alone or in combination of two or more as required.

  In the present invention, from the viewpoint of improving the durability of the resulting molded article, the organic polyisocyanate (H) is preferably selected from MDI, MDI and polymeric MDI, TDI alone or in combination, MDI and polymeric MDI are particularly preferable in consideration of odor and the like during the production of the conductive roll.

  Since MDI and polymeric MDI have been described in detail in the first section, description thereof will be omitted here, and TDI will be described in detail. TDI is a mixture of any proportion of two isomers of 2,4-tolylene diisocyanate (2,4-TDI) and 2,6-tolylene diisocyanate (2,6-TDI) It exists in the form of a single item). The isomer composition ratio of TDI can be obtained from a calibration curve based on the area percentage of each peak obtained by gel permeation chromatography or gas chromatography.

  The polyol used in the aforementioned isocyanate group-terminated urethane prepolymer is preferably hydrophobic. This is because when a hydrophilic polyol is used, the hygroscopicity of the resulting polyurethane foam increases, and the change in conductivity due to environmental changes tends to increase. Particularly preferred polyols are those having a substantially average number of functional groups of 2 to 4, a number average molecular weight of 1,000 to 10,000 (preferably 2,000 to 5,000), and an oxyethylene group content of 50% by mass or less. (Oxypropylene) polyol or poly (oxyethylene-oxypropylene) polyol. The poly (oxyethylene-oxypropylene) polyol includes, for example, a block copolymer type, a random copolymer type, or a poly (oxypropylene) polyol added with ethylene oxide at the terminal. When the substantial average functional group number is too small, no foam is formed, and when the substantial average functional group number is too large, the viscosity is high, so that a lack of thickness is likely to occur. When the number average molecular weight is too small, the hardness tends to be high, and when the number average molecular weight is too large, the viscosity is high, so that a lack of thickness is likely to occur. In the present invention, in consideration of the reactivity, it is most preferable to add ethylene oxide to the terminal of the poly (oxypropylene) polyol and have an ethylene oxide content of 5 to 15% by mass.

  In the isocyanate group-terminated prepolymer, the isocyanate group is in a stoichiometric excess of the hydroxyl group in terms of the number of moles of isocyanate groups and the number of hydroxyl groups, and the above MDI and polyol are reacted at 30 to 100 ° C. can get.

  The polyol (I) used in the present invention comprises a polymer polyol and a chain extender. As the polymer polyol and chain extender, the various polyols and chain extenders described in the above items 1 and 3 are used. Can be used. In the present invention, a polyol exhibiting hydrophobicity is preferred. This is because when a hydrophilic polyol is used, the hygroscopicity of the resulting polyurethane foam increases, and the change in conductivity due to environmental changes tends to increase. In addition, like the polyol used for the above-mentioned isocyanate group-terminated urethane prepolymer, the poly (oxyethylene-oxypropylene) polyol is, for example, a block copolymer type, a random copolymer type, or a terminal of the poly (oxypropylene) polyol. Including those with added ethylene oxide. When the substantial average functional group number is too small, no foam is formed, and when the substantial average functional group number is too large, the viscosity is high, so that a lack of thickness is likely to occur. When the number average molecular weight is too small, the hardness tends to be high, and when the number average molecular weight is too large, the viscosity is high, so that a lack of thickness is likely to occur. Considering the reactivity further, it is most preferable that ethylene oxide is added to the terminal of the poly (oxypropylene) polyol and the ethylene oxide content is 5 to 15% by mass.

  As the catalyst (J), the catalyst described in the above item 1 can be used, and as the foam stabilizer (K), a silicone foam stabilizer is preferred. As this silicone type foam stabilizer, for example, a reactive silicone type surfactant is preferable. One type of catalyst (J) and foam stabilizer (K) may be used, or two or more types may be used in combination. In addition to the foam stabilizer (K), if desired, an ionic surfactant such as cationic, anionic or amphoteric, or a nonionic surfactant such as various polyethers or polyesters may be used in combination. In general, the amount of the foam stabilizer (K) added is preferably in the range of 0.5 to 30% by mass, particularly preferably in the range of 2 to 10% by mass with respect to the polyol (I). When the addition amount of the foam stabilizer (K) is too small, it is difficult to obtain a homogeneous foam, and when it is too much, the foam stabilizer (K) tends to bleed from the foam.

  The conductivity-imparting agent (L) used in the present invention contains an ionic conductive agent (L1) containing one or both of potassium bis (trifluoromethanesulfonyl) imide and lithium bis (trifluoromethanesulfonyl) imide. Furthermore, the conductivity imparting agent (L) preferably contains conductive carbon (L2).

  Examples of the conductive carbon (L2) include carbon black such as furnace black, thermal black, channel black, acetylene black, ketjen black, and color black, and graphite.

  As the conductivity-imparting substance (L), the ratio when the ionic conductive agent (L1) and the conductive carbon (L2) are used in combination is (L1) :( L2) = 3: 97 to 99: 1 (mass ratio) ) Is preferable, and (L1) :( L2) = 50: 50 to 90:10 (mass ratio) is particularly preferable. By using together in this range, the electroconductive roll which has the electroconductivity by which the electroconductivity change by the environmental change is small and has very stable electroconductivity is obtained.

  In the present invention, the addition amount of the conductivity-imparting substance (L) with respect to the total amount of the organic polyisocyanate (H) and the polyol (I) is preferably in the range of 0.2 to 8.0% by mass, A range of 0.3 to 5.0% by mass is particularly preferable. If the introduction amount of the conductivity-imparting substance (L) with respect to the total amount is out of the range of 0.2 to 8.0% by mass, it is not preferable from the viewpoint that a desired electric resistance value and hardness cannot be obtained. .

In the present invention, as the conductivity imparting substance (L), a conductivity imparting substance other than the ionic conductive agent (L1) and the conductive carbon (L2), for example, a conductive metal powder such as copper, nickel, silver, or a fiber thereof Materials, metal oxides such as tin oxide, titanium oxide and indium oxide, or materials obtained by applying metal plating to various fillers, organic conductive fine powders such as polyacetylene, polypyrrole and polyacetylene, LiCF ₃ SO ₃ , NaClO ₄ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , NaSCN, KSCN, NaCl, etc. Li ⁺ , Na ⁺ , K ⁺ isochronous group 1 metal salt, NH ₄ ⁺ salt, etc. electrolyte, ^{_{also, Ca (ClO 4) 2 Ca}} 2+, periodic table group II metal salt or its like and 1,4-butanediol ^{Ba 2+} such as Ethylene glycol, polyethylene glycol, propylene glycol, can be used together and polyethylene glycol and a polyhydric alcohol complex or ethylene glycol monomethyl ether derivatives thereof, complexes of monools such as ethylene glycol monoethyl ether, and the like.

  In the present invention, known urethanization catalysts, foaming agents, ultraviolet absorbers, antioxidants, anti-coloring agents, fluorescent dyes, dispersible dyes, lubricants, surfactants and the like can be used.

In the present invention, the conductive roll satisfies all of the following conditions (A) to (C).
(A) Asker hardness of the conductive roll is C5 ° to C80 °
(B) The electrical resistance value of the conductive roll is 1 × 10 ⁴ to 1 × 10 ⁸ Ω
(C) The density of the flexible polyurethane foam is 0.1 to 0.8 g / cm ³

  That is, when the Asker hardness of the conductive roll is less than C5 °, the cells of the polyurethane foam are often rough. Conversely, when the Asker hardness exceeds C80 °, the types of rolls that can be applied are limited.

Also, if the electrical resistance value of the conductive roll is less than 1 × 10 ⁴ Ω, the current flows too much to control it, which is not preferable as the conductive roll. On the other hand, if it exceeds 1 × 10 ⁸ Ω, application of a considerably high voltage is necessary in order to pass a necessary current, which is not preferable.

  Furthermore, when the density of the flexible polyurethane foam is out of the above range, it tends to be difficult to set the Asker hardness within the predetermined range.

Especially in the conductive roll of the present invention,
(A) Asker hardness of the conductive roll is C20 ° to C50 °
(B) The electrical resistance value of the conductive roll is 1 × 10 ⁵ to 1 × 10 ⁷ Ω
(C) The density of the flexible polyurethane foam is 0.3 to 0.5 g / cm ^3.
For example, in a roll that comes into contact with a paper feed roll or a photosensitive drum, the balance of physical properties is optimal.

  Further, when forming the polyurethane foam, the ratio of isocyanate groups to active hydrogen groups present in the mixed liquid of the polyurethane foam-forming composition is 0.8 to 1.5 in terms of a molar ratio of isocyanate groups / active hydrogen groups. The organic polyisocyanate (H) and the polyol (I) are preferably blended and used so that the range is preferably 0.9 to 1.2.

  Next, the method for producing a conductive roll of the present invention will be described by taking a specific method for producing a conductive roll of the present invention as an example.

  The specific procedure for producing the conductive roll of the present invention may be, for example, by placing a metal core in advance in a mold cavity and cast-curing the polyurethane foam-forming composition, After forming the conductive polyurethane foam into a predetermined shape, a metal core material may be attached by adhesion. Specifically, a method in which an inert gas is introduced into a mixed solution of a polyurethane foam-forming composition with mechanical stirring and mixed with air bubbles is cast into a predetermined mold or the like and heat cured. . The polyurethane foam obtained by such a method has uniform fine cells and has an appropriate hardness. When so-called physical or chemical blowing agents are used, the cells are not uniform. In the present invention, the metal core material may be coated with an adhesive in advance.

  More specifically, a split mold or pipe mold having a length equal to or longer than the axial length of the polyurethane foam layer of the conductive roll, and a metal core material are prepared. The split mold is a combination of half-pipe shapes, and the upper and lower molds are combined to form a cylindrical foam-forming part. A metal core is set on the foam center axis. It is something that can be done. In the pipe-shaped mold, a metal core material can be set on the upper surface portion and the bottom surface portion along the center axis of the foam. Further, as the metal core material, a metal member obtained by plating zinc or the like on a steel material such as sulfur free-cutting steel, or a metal member such as aluminum or stainless steel is usually used.

  And after preparing the polyol premix which mix | blends the said specific polyol (I), catalyst (J), foam stabilizer (K), and electroconductivity imparting agent (L) previously, it is organic in this polyol premix. A mixture of polyisocyanate (H) mixed with sufficient inert gas is poured into the molding cavity, and the mixture is poured into an oven at a predetermined temperature (about 40 ° C. to 100 ° C.) for a predetermined time (10 minutes to 10 minutes). Heat for about 1 hour) to cure by foaming. After that, by removing the mold and grinding it as necessary, a conductive roll having a single layer structure in which a polyurethane foam layer is formed on the outer peripheral surface of the shaft body can be obtained. Thereafter, if necessary, the surface of the foam layer may be painted with a conductive, semiconductive, or insulating paint.

  The thickness of the polyurethane foam layer in the conductive roll thus obtained is usually 2 to 20 mm, preferably 3 to 15 mm.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these. In Examples and Comparative Examples, unless otherwise specified, the ratio is a mass ratio, and “%” is “mass%”. Also, the embodiment will be described separately for each item as described above.

A. Example of production method of flexible polyurethane foam [Synthesis of isocyanate group-terminated urethane prepolymer]
(Synthesis Example 1)
Capacity: equipped with stirrer, cooling pipe, nitrogen introduction pipe, thermometer: A 1,000 ml reactor was charged with 270 g of MDI-1 and 730 g of polyol-1, and reacted at 80 ° C. for 4 hours while stirring. An isocyanate group-terminated urethane prepolymer NCO-1 was obtained. The isocyanate content of NCO-1 was 6.0%.

(Synthesis Example 2)
In the same reactor as in Synthesis Example 1, 270 g of MDI-1, 468 g of polyol-1 and 262 g of polyol-2 were charged and reacted at 80 ° C. for 4 hours with stirring, and an isocyanate group-terminated urethane prepolymer NCO- 2 was obtained. The isocyanate content of NCO-2 was 6.0%.

Diphenylmethane diisocyanate (MDI) containing 1% of MDI-1: MDI isomer mixture in each synthesis example. MDI isomer mixture is an isomer other than 4,4'-MDI (2,2'-MDI and 2,2 4'-MDI).
Polyol-1: Poly (oxytetramethylene) polyol with nominal average functional group = 2 and number average molecular weight = 2,000 Polyol polyol-2: Poly (oxypropylene) with nominal average functional group = 3, number average molecular weight = 3,000 Polyol

[Preparation of polyol premix]
(Formulation Examples 1-30)
Volume: Polyol premixes OH-1 to 29 were prepared in the reactor shown in Tables 1 to 4 in a 2,000 ml reactor.

In blending examples 1 to 30 and Tables 1 to 4, polyol-1: nominal average functional group number = 2, number average molecular weight = 2,000 poly (oxytetramethylene) polyol polyol-2: nominal average functional group number = 3, number average Poly (oxypropylene) polyol of molecular weight = 3,000 1,4-BD: 1,4-butanediol SFE-1: sorbitan monolaurate SFE-2: sorbitan sesquioleate SFE-3: sorbitan trioleate SFE-4 : Sorbitan monooleate SFE-5: Sorbitan monopalmitate OS-1: Silicone surfactant (SF-52938, manufactured by Toray Dow Corning)
DOTDL: Dibutyltin dilaurate

[Manufacture of flexible polyurethane foam]
Example 1
Liquid temperature blended with the isocyanate index shown in Table 5: Polyol premix OH-1 at 25 ° C and polyisocyanate NCO-1 at 25 ° C were mixed and stirred for 1 minute to mix dry air. The mixed solution is poured into a mold (10 cm × 10 cm × 10 cm, upper open), and then the mold in which the mixed solution is cast is left in a hot air oven adjusted to 80 ° C. for 2 hours to cure the foamed polyurethane raw material. I let you. The cured polyurethane foam was removed from the mold to produce a polyurethane foam.

(Examples 2 to 20), (Comparative Examples 1 to 10)
Using the raw materials shown in Tables 5 to 8, polyurethane foam was produced in the same procedure as in Example 1.

[Evaluation of flexible polyurethane foam]
The evaluation items and measurement method of the foam are as follows.
Density: Determined according to JIS K 6401.
C hardness: Measured with Asker hardness meter C type.
Tensile strength, elongation, impact resilience: determined according to JIS K 6301.

  From Tables 5-8, the foam of the Example using sorbitan fatty acid ester has a low density, and it is possible to sufficiently include air in the reaction mixture during the production of the PTMG-based soft mechanical floss foam. Indicated. Further, the physical properties were high in strength and repulsion, and the effect of using PTMG as a polyol was confirmed. Those using a silicon-based surfactant had a high density. This indicates that the silicon-based surfactant showed a bubble breaking effect. Moreover, the impact resilience was also low. Moreover, although the density which did not use a foam stabilizer was lower than that using a silicon surfactant, the density was higher than that of a sorbitan fatty acid ester system. From this, it was confirmed that sorbitan fatty acid ester is an effective foam stabilizer in the mechanical foam formulation of PTMG polyurethane foam. In the PTMG-based water-foamed foam, the elongation was particularly lower than in the examples. This seems to be because the flexibility of the resulting foam is impaired due to the urea group generated during foaming. Furthermore, the PPG-based soft mechanical floss foam has low strength and elongation. Regarding the PTMG-based polyol content of the foam, from Example 2 and Comparative Examples 8 and 10, Example 8 and 10 show no significant physical difference, but the physical property difference between Example 2 and Comparative Example 8 is It turned out that it appeared remarkably.

B. Example of production method of flexible polyurethane foam [analysis of foam stabilizer]
Results of measuring the hydroxyl value, silicon content, mass ratio of polysiloxane part / polyether part, and mass ratio of oxyethylene group (EO) / oxypropylene group (PO) in the polyether part for foam stabilizers 1 to 4 Is shown in Table 9.

In Table 9, the terminal group was confirmed by ¹ H-NMR.
Silicon content: measured by the ashing method described above.
Mass ratio of polysiloxane part / polyether part: Measured by ¹ H-NMR.
EO / PO mass ratio of the polyether part: After the Corrish decomposition, the recovered product was measured by ¹ H-NMR. EO is ethylene oxide and PO is propylene oxide.
Foam stabilizer molecular weight distribution: measured by the GPC method described above.
Molecular weight distribution of the polyether portion: After the Corish decomposition, the recovered product was measured by the GPC method described above.

[Synthesis of isocyanate group terminal urethane prepolymer]
(Synthesis example)
Capacity equipped with stirrer, cooling pipe, nitrogen introduction pipe and thermometer: Into a 100 L reactor, 350 g of MDI-1 and 650 g of polyol-1 were charged, and reacted at 80 ° C. for 4 hours with stirring to produce an isocyanate group. A terminal urethane prepolymer NCO-1 was obtained. The isocyanate content of NCO-1 was 9.0%.

In the synthesis examples, diphenylmethane diisocyanate (MDI) containing 50% of MDI-1: MDI isomer mixture, wherein the MDI isomer mixture is an isomer other than 4,4'-MDI (2,2'-MDI and 2,2). 4'-MDI).
Polyol-1: Nominal average functional group number = 3, number average molecular weight = 3,000, oxyethylene group content = 11% terminal oxyethylene-capped poly (oxypropylene) polyol

[Preparation of polyol premix]
(Formulation Examples 1-18)
Volume: Polyol premixes OH-1 to -18 were prepared in the reactor shown in Tables 10 and 11 in a 2 L reactor.

In Formulation Examples 1 to 18 and Tables 10 and 11, Polyol-1: Nominal average functional group number = 3, number average molecular weight = 3,000, oxyethylene group content = 11% terminal oxyethylene cap poly (oxypropylene) polyol 1,4-BD: 1,4-butanediol TEDA-L33: amine catalyst (manufactured by Tosoh Corporation)

[Manufacture of polyurethane foam]
Example 1
Liquid temperature blended at a ratio shown in Table 12: 25 ° C. polyol premix OH-1 and liquid temperature: 25 ° C. polyisocyanate NCO-1 were mixed, stirred for 1 minute and mixed with dry air Was poured into a mold (10 cm × 10 cm × 10 cm, upper open), and then the mold into which the mixed liquid had been poured was left in a hot air oven adjusted to 80 ° C. for 2 hours to cure the polyurethane foam raw material. . The cured polyurethane foam was removed from the mold to produce a polyurethane foam.

(Examples 2-8), (Comparative Examples 1-10)
Using the raw materials shown in Tables 12 and 13, polyurethane foam was produced in the same procedure as in Example 1.

[Evaluation of polyurethane foam]
Evaluation items and measurement methods of polyurethane foam are as follows.
Density: Determined according to JIS K 6401.
The density measurement sample is a liquid two minutes after mixing the polyisocyanate and the polyol and a foam after the curing reaction.
Hardness: Measurement cell state by Asker hardness tester C type: A flexible polyurethane foam is cut, and the number of cells per unit area of the cross section and the radius of the cell are measured. There were 5 cut points.

  From Tables 10 to 13, when the foam stabilizer defined in the present invention is used, the standard deviation of the cell radius in the example is about 0.04 mm, whereas the standard deviation of the cell radius in the comparative example is From 0.05 to 0.06 mm, it can be said that the example is a more uniform foam. Moreover, it was confirmed that the examples had a sufficiently low density.

C. Example of production method of conductive polyurethane foam [Synthesis of isocyanate group-terminated urethane prepolymer]
(Synthesis example)
Capacity equipped with stirrer, cooling pipe, nitrogen introduction pipe, thermometer: A 1,000 ml reactor was charged with 450 g of MDI-1 and 550 g of polyol-1 and reacted at 80 ° C. for 4 hours with stirring. The polyisocyanate liquid NCO-1 was obtained. The isocyanate content of NCO-1 was 14.0%.

In the synthesis example, MDI-1: MDI isomer mixture content = 50% diphenylmethane diisocyanate (MDI), wherein the MDI isomer mixture is an isomer other than 4,4′-MDI (2,2′-MDI and 2 , 4'-MDI).
Polyol-1: Poly (oxypropylene) polyol having a nominal average functional group number = 2 and a number average molecular weight = 4,000

[Preparation of polyol liquid]
(Formulation Examples 1-9)
Each raw material was charged in a reactor having a capacity of 2,000 ml equipped with a high shearing stirrer and blended as shown in Table 14, and stirred and mixed to prepare polyol liquids OH-1 to OH-9.

In Formulation Examples 1 to 9 and Table 14, Polyol-2: Nominal average functional group number = 3, Number average molecular weight = 3,000, Oxyethylene group content = 20% ethylene oxide capped poly (oxypropylene) polyol 1,4 -BD: 1,4-butanediolamine-1: reactive amine catalyst silicon-1: silicon foam stabilizer VGCF: manufactured by Showa Denko (trade name: VGCF), fiber diameter = 150 nm, aspect ratio = 200, fiber length = Vapor grown carbon fiber AB having a specific surface area of 15 nm, a specific surface area of 13 m ² / g, and a bulk specific gravity of 0.04: manufactured by Denki Kagaku Kogyo (trade name: Denka Black, powdered product), average particle size = 35 nm, specific surface area = 68 m ² / g, acetylene black with bulk specific gravity = 0.04

[Manufacture of conductive polyurethane foam]
Example 1
Liquid temperature: 45 ° C. polyol liquid OH-1 was mechanically stirred for 5 minutes with a mixer and mixed with dry air. Thereafter, liquid temperature shown in Table 15: 45 ° C. polyisocyanate liquid NCO-1 was mixed, Furthermore, the mixed liquid in which dry air was further mixed by stirring for 1 minute was poured into a mold on which a shaft was set, and then the mold into which the mixed liquid was cast was placed in a hot air oven adjusted to 80 ° C. for 2 hours. The foamed polyurethane raw material was cured by allowing it to stand. The cured polyurethane foam was removed from the mold and polished with a grindstone so as to have a predetermined shape, thereby producing a conductive roll made of polyurethane foam.

  While measuring the volume resistivity of the skin layer of this conductive roll, appearance, density (only the foam part), and Asker hardness C were evaluated. The results are shown in Table 15.

(Examples 2 to 5), (Comparative Examples 1 to 4)
In the same manner as in Example 1, OH-1 was changed to OH-2 to 9 to produce and evaluate foams (rolls). The results are shown in Table 15.

〔Test method〕
(Form characteristics)
Appearance: The state of the foam was visually evaluated.
Density: Determined according to JIS K 6401.
(Roll characteristics)
Hardness: Measured with Asker hardness meter C type.
Resistance value: A charging member (roll) is placed on an aluminum plate, and an electrode is connected to the shaft and the aluminum plate protruding from the foam. A voltage of 100 V or 1,000 V was applied between the electrodes, and the volume resistance value was calculated from the obtained electric resistance value and roll size. The measuring instrument used was R8340 manufactured by Advantest. The measurement atmosphere was measured at three levels: (A) 10 ° C./15 RH%, (B 23 ° C./55 RH%, (C) 28 ° C./85 RH%.
Temperature dependence of resistance value (conductivity): Evaluation was based on the difference in logarithm of resistance value in the measurement atmosphere of (C) from the logarithm of resistance value in the measurement atmosphere of (A).

  Table 15 shows that the roll using the conductive polyurethane foam obtained by the present invention is excellent in various performances, and in particular, the resistance value has a small temperature dependency. On the other hand, the comparative example has low conductivity, and the temperature dependency of conductivity is large.

D. Example of conductive roll and method for producing the conductive roll [Synthesis of isocyanate group-terminated prepolymer]
Using a reactor having a capacity of 1,000 ml equipped with a stirrer, a cooling pipe, a nitrogen introducing pipe, and a thermometer, MDI-1 or MDI-2 and polyol-1 were charged at a blending ratio shown in Table 1 described later. The reaction was carried out at 80 ° C. for 4 hours with stirring to obtain isocyanate group-terminated prepolymers NCO-1 and NCO-2.

  In Table 16, MDI-1 is diphenylmethane diisocyanate (MDI) containing 50% MDI isomer mixture which is a mixture of 2,2'-MDI and 2,4'-MDI, and MDI-2 is MDI isomer. MDI containing 18% body mixture. Polyol-1 is a poly (oxypropylene) polyol in which ethylene oxide is added to the terminals having a nominal average functional group number = 3 and a number average molecular weight = 3,000 (ethylene oxide content 11%).

[Preparation of polyol premix]
Raw materials were charged in a reactor having a capacity of 2,000 ml according to the formulation shown in Table 17 and Table 18 described later, and kneaded sufficiently to prepare polyol premixes OH-1 to 13.

  In Tables 17 and 18, polyol-1 is the same as in Table 16, and polyol-2 is a poly (oxyethylene-oxypropylene) polyol having a nominal average functional group number = 2 and a number average molecular weight = 2,000, Polyol-3 is a poly (oxypropylene) polyol having a nominal average number of functional groups = 2 and a number average molecular weight = 4,000, and Polyol-4 is a poly having a nominal average number of functional groups = 3 and a number average molecular weight = 6,000. (Oxypropylene) polyol, Polyol-5 is a poly (oxypropylene) polyol having a nominal average functional group number = 4 and a number average molecular weight = 8,000. 1,4-BD is 1,4-butanediol and is a chain extender. TEDA-L33 is an amine catalyst (manufactured by Tosoh Corporation). SF-2938F is a silicon foam stabilizer (made by Toray Dow Silicone).

[Manufacture of conductive rolls]
The polyol premixes OH-1 to OH-13 having a liquid temperature of 25 ° C. blended at the blending ratios shown in Table 17 and Table 18 were mechanically stirred for 5 minutes with a mixer and mixed with dry air, and then shown in Table 1. Polyisocyanate NCO-1 or NCO-2 is mixed, and further stirred for 2 minutes to additionally mix dry air to obtain a polyurethane foam-forming composition mixture. And after pouring the mixed liquid obtained in this way into the split mold which set the metal core material, it left still for 2 hours in the hot-air oven adjusted to 80 degreeC, and also made room temperature. Let it cure for 3 days. Thereafter, the roll is taken out from the mold, the surface is ground so as to have a predetermined shape, and the conductive rolls of Examples 1 to 10 and Comparative Examples 1 to 3 shown in Table 19 and Table 20 described later are used. Got.

The electrical resistance values of the conductive rolls of Examples 1 to 10 and Comparative Examples 1 to 3 thus obtained were measured as follows.
The conductive roll was allowed to stand on an aluminum plate of 300 mm × 300 mm × 3 mm, and the electrode was connected to the core material protruding from the foam and the aluminum plate. Next, a voltage of 1,000 V was applied between the electrodes, and the electrical resistance value was measured. The electrical resistance value was an average value measured 5 times or more by using R8340 manufactured by Advantest as a measuring instrument and appropriately rotating the conductive roll. The measurement atmosphere was 23 ° C. × 55% RH. In addition, the variation of the electrical resistance value is evaluated by the difference between the maximum and minimum logarithms of the measured values, and the stability of the electrical resistance value is 5 ° C. × 35% RH and 28 ° C. × 85% RH in the measurement atmosphere. The measurement was performed under two conditions, and the results measured in an atmosphere of 23 ° C. × 55% RH were evaluated together. In addition, even in the atmosphere of 5 ° C. × 35% RH and 28 ° C. × 85% RH, similarly to the atmosphere of 23 ° C. × 55% RH, the conductive roll was appropriately rotated and measured five times or more. The value was the electrical resistance value of the conductive roll in the measurement atmosphere.

  Moreover, at the time of manufacture of each electroconductive roll, the density of the liquid 2 minutes after mixing polyisocyanate and a polyol premix and the density of the polyurethane foam part after grinding were measured.

  Moreover, the Asker hardness of each conductive roll of Example 1 to Example 10 and Comparative Example 1 to Comparative Example 3 was measured with an Asker hardness meter C type.

The results are shown in Table 19 and Table 20.
From Table 19 and Table 20, in Examples 1 to 10 including the ionic conductive agent, it was confirmed that all of the electric resistance value, density, and Asker hardness were in a favorable range. In addition, in Examples 1 to 10 including the ionic conductive agent, the change in the electrical resistance value due to the environmental change is small and the variation in the electrical resistance value depending on the site is also small compared to Comparative Examples 1 to 3. Became clear.

  Further, in Examples 4, 9, and 10 in which the ionic conductive agent and the conductive carbon are used in combination, the change in the electrical resistance value due to the environmental change is further smaller and more stable than those using only the ionic conductive agent. It was confirmed that the obtained conductivity was obtained.

  The flexible polyurethane foam obtained by the present invention includes various rolls such as toner conveying rolls, transfer rolls, charging rolls, and developing rolls of electrophotographic apparatuses, bedding such as pillows and mattresses, cosmetic puffs, packing, sealing materials, carpet backings, It is ideal for medical equipment such as supporters, covers such as microphones, earphones and headphones, and clothing. Moreover, the conductive polyurethane foam and conductive roll obtained by the present invention are optimal for various rollers and can be used as various elastic members, particularly conductive elastic members.

Claims (3)

In a method for producing a flexible polyurethane foam, wherein a reaction mixture of an isocyanate liquid containing an inert gas and a polyol liquid is reacted in the presence of a catalyst and a surfactant, the polyurethane foam is derived from poly (oxytetramethylene) polyol . A method for producing a flexible polyurethane foam, comprising 50% by mass or more of a structural unit and 0.1 to 5% by mass of a sorbitan fatty acid ester as a surfactant based on the polyurethane foam.   The production method according to claim 1, wherein the isocyanate liquid contains an isocyanate group-terminated urethane prepolymer obtained by reacting MDI and poly (oxytetramethylene) polyol.   The production method according to claim 1, wherein the polyol liquid contains poly (oxytetramethylene) polyol.