JP2020189948A - Conductive polyurethane foam and its manufacturing method - Google Patents

Abstract

To provide a conductive polyurethane foam that simultaneously satisfies suppression of occurrence of bleeding of such as a conductive agent and low hardness, and has excellent image display property when applied to an image formation device of an electronic photographic method.SOLUTION: An urethane foam obtained by curing a foamable composition obtained by foaming a composition containing a polyurethane raw material (I) by a mechanical froth method, in which the polyurethane raw material (I) contains an urethane prepolymer (A) having an ion conductive group and an active energy beam polymerizable functional group, and an active energy beam polymerizable silicone (B), and a gel fraction when an extraction solvent in JIS K 6796 is rendered acetone is 90% or larger.SELECTED DRAWING: None

Description

The present invention relates to a conductive polyurethane foam preferably used in an electrophotographic image forming apparatus and a method for producing the same.

An electrophotographic image forming apparatus such as a laser printer has a charging roll for charging the photosensitive drum. The conductive roll body used for this charging roll is required to have conductivity and elasticity.

Patent Document 1 discloses a conductive elastic roller provided with an elastic layer made of an ultraviolet curable urethane prepolymer containing a conductive agent.

Japanese Unexamined Patent Publication No. 2016-129649

However, it is difficult for such a conductive roll to simultaneously suppress the generation of bleeding of a conductive agent or the like and the adhesion to a photosensitive drum or the like, and the image displayability may be inferior.

Therefore, an object of the present invention is to provide a conductive polyurethane foam that simultaneously satisfies both suppression of bleeding such as a conductive agent and low hardness, and is therefore excellent in image display when applied to an electrophotographic image forming apparatus. It is to be.

The present inventors have diligently studied toward the realization of the above object, and achieved a low hardness while achieving a high gel fraction by forming a foam obtained by foaming and curing a composition containing a specific component. Therefore, they have found that the above problems can be solved, and have completed the present invention. That is, the present invention is as follows.

The present invention
A urethane foam obtained by curing a foamable composition obtained by foaming a composition containing a polyurethane raw material (I) by a mechanical floss method.
The polyurethane raw material (I) contains a urethane prepolymer (A) having an ionic conductive group and an active energy ray-polymerizable functional group, and an active energy ray-polymerizable silicone (B).
The urethane foam is a conductive polyurethane foam having a gel fraction of 90% or more in which the extraction solvent in JIS K 6996 is acetone.

In addition, the present invention
A method for producing a conductive polyurethane foam.
A polyol (a-1), a polyisocyanate (a-2), a conductive agent (a-3) having an active hydrogen-containing group or a functional group capable of reacting with active hydrogen and an ionic conductive group, and an active hydrogen-containing group. Alternatively, the polyurethane raw material (I) containing the prepolymer (A) synthesized from the active energy ray-polymerizable compound (a-4) having a functional group capable of reacting with active hydrogen and the active energy ray-polymerizable silicone (B). And the preparation process to prepare
A foaming step of obtaining a foamable composition by foaming the composition containing the polyurethane raw material (I) by a mechanical floss method.
Including an irradiation step of irradiating the effervescent composition with active energy rays.
The urethane foam is a method for producing a conductive polyurethane foam, which comprises using acetone as an extraction solvent in JIS K 6996 and having a gel fraction of 90% or more.
In addition, this manufacturing method further includes a coating step of coating the foamable composition on the roll shaft while rotating the roll shaft after the adjustment step, thereby forming a roll-shaped conductive polyurethane foam. It may be manufactured.

Further, the present invention is a member for an image forming apparatus made of the conductive polyurethane foam.

Further, the present invention is an image forming apparatus including the member for the image forming apparatus.

Here, the effervescent composition further comprises polythiol (III).
The number of functional groups of the polythiol (III) is preferably 2.0 to 6.0.

SH-INDEX ((content [g] of polythiol (III) × number of functional groups of polythiol (III)) / (molecular weight [g / mol] of polythiol (III) × prepolymer (A)) in the effervescent composition The amount of active energy ray-polymerizable functional group [mol]) is preferably in the range of 0.5 to 1.5.

The urethane foam preferably has a 10% CLD of 200 kPa or less as measured by the following method.
(Measurement method of 10% CLD)
According to JIS K 6400-2, the sample size is 50 mm × 50 mm × thickness 5 mm, 50% precompression is performed once, and then the CLD at 10% compression is measured.

The viscosity of the prepolymer (A) at 80 ° C. according to JIS K 7117-2 is preferably 1 to 20 Pa · s.

According to the present invention, it is possible to provide a conductive roll body which simultaneously satisfies the suppression of bleeding such as a conductive agent and low hardness, and is therefore excellent in image displayability.

Preferred examples of the functional group containing active hydrogen in the present invention include a hydroxyl group, an amino group, a thiol group, and a carboxyl group. The functional group containing active hydrogen may be one type or a combination of a plurality of types.

Preferred examples of the functional group capable of reacting with active hydrogen in the present invention include an alkoxy group, an isocyanate group, and an epoxy group. The functional group capable of reacting with active hydrogen may be one type or a combination of a plurality of types.

The ionic conductive group in the present invention indicates a functional group having a cationic or anionic property. The ionic conductive group is preferably a cationic group derived from, for example, a quaternary ammonium salt, a phosphonium salt, a sulfonium salt, a pyridinium salt, an imidazolium salt or the like. Examples of the anionic ionic conductive group include a sulfonic acid group and the like.

The active energy ray in the present invention indicates X-ray, electron beam, ultraviolet light, visible light, infrared ray and the like. In addition, ultraviolet rays, visible rays, and infrared rays may be collectively referred to as "light".

The active energy ray-polymerizable in the present invention indicates that it has an active energy ray-reactive group (preferably a photoreactive functional group), and more preferably it is not ethylenic or acetylene (preferably ethylenically). It is shown to have a functional group containing a saturated carbon bond. Examples of the functional group containing an unsaturated carbon bond include an alkenyl group (vinyl group, allyl group, butenyl group, petenyl group, hexenyl group and the like), a (meth) acryloyl group and the like. Further, the active energy ray-reactive group may be referred to as an active energy ray-polymerizable functional group.

The solid content in the present invention means a component other than a solvent (particularly an organic solvent), or a mass or volume thereof.

The conductive agent in the present invention is an agent capable of improving the conductivity of the urethane foam by being added to the urethane foam. For example, the resistance value is 11 (LogΩ) or less (preferably 9). (LogΩ) or less) is shown. The resistance value can be measured according to the following method.
A sample formed on a roller of A4 size and a wall thickness of 2 mm is placed in a flat plate shape, and 500 gf is loaded on each end. Connect the terminal of R8340a (name of measuring device) and measure the average resistance value when 100V × 10sec is applied. The measurement conditions are shown below.
Measuring instrument ADVANTEST R8340a
Applied voltage 100V
Application time 10 sec
Measurement environment 22 ° C 55% RH
Load 500gf (load on both ends)
Measurement method Flat plate measurement method

Hereinafter, a foamable composition for obtaining a conductive polyurethane foam, a method for producing the conductive polyurethane foam, a structure of the conductive polyurethane foam, and an image display device will be described. Hereinafter, the conductive polyurethane foam may be simply referred to as a urethane foam.

<<<<< Effervescent composition >>>>>
The conductive polyurethane foam is obtained by curing a foamable composition containing the polyurethane raw material (I). The foamable composition is obtained by foaming a composition containing the polyurethane raw material (I) by a mechanical floss method. The effervescent composition preferably contains polythiol (III) and may further contain other component (IV). The mechanical floss method is usually carried out in the presence of a foaming gas (II), and the foaming composition also contains this foaming gas (II), but the finally obtained conductive polyurethane foam. As itself, the foam-forming gas (II) may be contained in the structure (inside the foam cell), or the foam-forming gas (II) may not be contained. Hereinafter, each component (I) to (IV) will be described.

<<< Polyurethane raw material (I) >>>
The polyurethane raw material (I) contains a prepolymer (A) and an active energy ray-polymerizable silicone (B).

<< Prepolymer (A) >>
The prepolymer (A) has an ionic conductive group and an active energy ray-polymerizable functional group incorporated in the skeleton.

The urethane prepolymer (A) is usually obtained from a raw material containing a polyol and a polyisocyanate, but in any form, the urethane prepolymer has an ionic conductive group and an active energy ray-polymerizable functional group. It may be introduced in (A). The urethane prepolymer (A) is, for example, a polyol (a-1), a polyisocyanate (a-2), an active hydrogen-containing group or a conductive agent (a-3) having a functional group capable of reacting with active hydrogen, and It is obtained by synthesizing an active energy ray-polymerizable compound (a-4) having an active hydrogen-containing group or a functional group capable of reacting with active hydrogen.

These (a-1) to (a-4) may have different components from each other, but the conductive agent (a-3) and the active energy ray-polymerizable compound (a-4) are two or more. When it has an alcoholic hydroxyl group, these may be treated as a polyol (a-1), and there are two conductive agents (a-3) and two active energy ray-polymerizable compounds (a-4). When it has the above isocyanate groups, they may be treated as polyisocyanate (a-2).

The composition for prepolymer synthesis containing these (a-1) to (a-4) may be used as the prepolymer composition (a).

The prepolymer (A) is a conductive agent having no functional group capable of reacting with monool, monoisocyanate, active hydrogen-containing group and active hydrogen, active hydrogen-containing group and active hydrogen, as long as the effect of the present invention is not impaired. It may contain an active energy ray-polymerizable compound having no functional group capable of reacting with, and the like.

The viscosity of the prepolymer (A) according to JIS K 7117-2 at 80 ° C. is preferably 1 to 20 Pa · s, more preferably 1 to 10 Pa · s, and 1.5 to 7. It is more preferably 5 Pa · s. This viscosity can be changed by adjusting the content of each component and the like.

Hereinafter, each component of (a-1) to (a-4) will be described. Note that (a-1) to (a-4) shown below are examples, and can be appropriately changed as long as the effects of the present invention are not impaired.

<Polyprethane (a-1)>
The polyol (a-1) is a compound having two or more hydroxyl groups in one molecule, and is not particularly limited as long as it does not inhibit the effect of the present invention.

Examples of the polyol compound include polyester polyol, polycarbonate polyol, polyether polyol, polyester ether polyol, polydiene-based polyol, hydrogenated polydiene polyol and the like.

Examples of the polyester polyol include a polyester polyol obtained by dehydration condensation reaction of a polyol and a polycarboxylic acid, a polyester polyol obtained by ring-opening polymerization of a lactone monomer such as ε-caprolactone and methylvalerolactone, and the like.

The polyol forming the polyester polyol is not particularly limited as long as it does not interfere with the effects of the present invention.

As the polyol, for example
Ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1 , 5-Pentanediol, Neopentyl glycol, 1,8-Octanediol, 1,9-Nonanediol, 1,4-Tetracosandiol, 1,6-Tetracosandiol, 1,4-Hexacosandiol, 1, Fatal polyols such as 6-octacosandiol glycerin, trimethylolpropane, trimethylolethane, hexanetriol, pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin, dipentaerythritol;
Alicyclic groups such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, cyclohexanedimethanol, tricyclodecanedimethanol, cyclopentadienedimethanol, 2,5-norbornanediol, 1,3-adamantandiol, and dimerdiol. Polypolymer;
Aromatic polyols such as bisphenol A, bisphenol F, phenol novolac, cresol novolac;
And so on. These can be used alone or in combination of two or more.

The polycarboxylic acid has a plurality of carboxyl groups in its molecular structure and is not particularly limited as long as it does not inhibit the effect of the present invention.

Examples of polycarboxylic acids include
Aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid;
Aromatic polycarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid;
Alicyclic polycarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid and hexahydroisophthalic acid;
Acid esters of these polycarboxylic acids;
And so on.

Examples of the polycarbonate polyol include, for example.
Ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1 , 5-Pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, and other polyhydric alcohols.
Examples thereof include those obtained by reacting with diethylene carbonate, dimethyl carbonate, diethyl carbonate and the like.

Examples of the polyether polyol include, for example.
Examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and the like obtained by polymerizing cyclic ethers such as ethylene oxide, propylene oxide and tetrahydrofuran, and copolyethers thereof.

It can also be obtained by polymerizing the above cyclic ether using a polyhydric alcohol such as glycerin or trimethylolethane.

Examples of the polyester ether polyol include those obtained by a dehydration condensation reaction of a polycarboxylic acid and a glycol such as diethylene glycol or a propylene oxide adduct.

Examples of polycarboxylic acids include
Aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid;
Aromatic polycarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid;
Alicyclic polycarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid and hexahydroisophthalic acid;
Acid esters of these polycarboxylic acids;
And so on.

As the polyol compound, only one kind may be used alone, or two or more kinds may be used.

<Polyisocyanate (a-2)>
The polyisocyanate (a-2) is a compound having two or more isocyanate groups in one molecule, and is not particularly limited as long as it does not inhibit the effect of the present invention.

Examples of polyisocyanates include, for example.
As bifunctional polyisocyanates, 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), m-phenylenediisocinate, p-phenylenediocyanate, 4,4 ′ -Diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 2,2'-diphenylmethane diisocyanate (2,2'-MDI), hydrogenated MDI, Xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylenedisonate, 3,3'-dimethoxy-4,4'-biphenylenediocyanate, polymethylene polyphenyl polyisocyanate, 1,5-naphthalene diisocyanate, Aromatic substances such as xylylene diisocyanate (XDI), hydrogenated XDI, tetramethylxylene diisocyanate (TMXDI), etc.;
Alicyclics such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and methylcyclohexanediisocyanate;
Butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, lysine diisocyanate and other alkylene-based materials;
Polymeric MDI as a bifunctional or higher polyisocyanate;
As trifunctional or higher functional polyisocyanates, 1-methylbenzol-2,4,6-triisocyanate, 1,3,5-trimethylbenzol-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate Isocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2', 5,5'tetraisocyanate, triphenylmethane -4,4', 4 "-triisocyanate, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecantriisocyanate, bicycloheptane triisocyanate, 1,8-diisocyanate Methyl octane, etc .;
Modified products and derivatives of these polyisocyanates;
And so on.

As the polyisocyanate (a-2), only one type may be used alone, or two or more types may be used.

The content of the polyisocyanate is not particularly limited, but can be blended so that the isocyanate index is 50 to 200, 70 to 150, or the like. The isocyanate index is a numerical value representing the equivalent ratio of isocyanate groups in the polyisocyanate (a-2) to the hydroxyl group capable of reacting with the polyisocyanate (a-2) in the prepolymer composition (a) as a percentage. ..

<Conducting agent (a-3)>
The conductive agent (a-3) is not particularly limited as long as it is a conductive agent having an active hydrogen-containing group or a functional group capable of reacting with active hydrogen.

Examples of the conductive agent (a-3) include those containing a quaternary ammonium salt, a phosphonium salt, a sulfonium salt, a pyridinium salt, an imidazolium salt and the like in the skeleton.

The conductive agent (a-3) preferably contains a quaternary ammonium salt in the skeleton.

As the conductive agent (a-3), only one kind may be used alone, or two or more kinds may be used.

The content of the conductive agent (a-3) is not particularly limited, but is preferably 0.01 to 5% by mass in the prepolymer composition (a).

<Active energy ray-polymerizable compound (a-4)>
The active energy ray-polymerizable compound (a-4) is not particularly limited as long as it is an active energy ray-polymerizable compound having an active hydrogen-containing group or a functional group capable of reacting with active hydrogen. The active energy ray-polymerizable compound (a-4) may contain a plurality of such functional groups in one molecule.

Examples of the active energy ray-polymerizable compound (a-4) having a hydroxyl group as an active hydrogen-containing group include monool having an allyl ether group such as allyl ether glycol and hydroxyethyl allyl ether; 2-hydroxyethyl vinyl ether and diethylene glycol mono. Monools having a vinyl ether group such as vinyl ether, 4-hydroxybutyl vinyl ether; hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate and the like ( Meta) Monool having an acrylic group and the like can be mentioned.

As the active energy ray-polymerizable compound (a-4), only one kind may be used alone, or two or more kinds may be used.

The content of the active energy ray-polymerizable compound (a-4) is not particularly limited, but is preferably 1 to 25% by mass in the prepolymer composition (a).

<< Active energy ray-polymerizable silicone (B) >>
The active energy ray-polymerizable silicone (B) is not particularly limited as long as it is a silicone having a functional group containing an unsaturated carbon bond in the molecule. The active energy ray-polymerizable silicone (B) may contain a plurality of functional groups containing unsaturated carbon bonds (preferably 2 to 3 in one molecule) in one molecule.

The active energy ray-polymerizable silicone (B) is, for example, at least one of the terminal and side chains of the main chain of a nonionic surfactant having a siloxane structure (for example, a dimethylsiloxane-polyoxyalkylene copolymer, etc.). Examples thereof include a compound having a (meth) acryloyl group ((meth) acrylic-modified silicone). More specifically, the active energy ray-polymerizable silicone (B) includes both-terminal silanol polydimethylsiloxane, both-terminal silanol polydiphenylsiloxane-dimethylsiloxane copolymer, and both-terminal silanol polydimethyldiphenylsiloxane. , Trialkylalkoxysilanes such as trimethylethoxysilane, and ethylenically unsaturated bond-containing silane compounds such as (3-acryloxypropyl) methyldimethoxysilane, in the presence of a catalyst (eg, tin 2-ethylhexanoate). Below, those obtained by a dehydration condensation reaction and a dealcoholization reaction can be mentioned.

As the active energy ray-polymerizable silicone (B), only one type may be used alone, or two or more types may be used.

The weight average molecular weight of the active energy ray-polymerizable silicone (B) is not particularly limited, but is preferably 500 to 50,000, and more preferably 1,000 to 10,000.

The content of the active energy ray-polymerizable silicone (B) is not particularly limited, but is preferably 0.01 to 5% by mass in the effervescent composition.

<<< Gas for foaming (II) >>>
The foaming gas is not particularly limited, but is preferably a gas that does not adversely affect the reaction such as polyol and isocyanate, and is preferably dry air or an inert gas (for example, nitrogen, carbon dioxide, helium, argon, etc.). More preferably.

The content of the foaming gas (II) in the foamable composition can be appropriately changed according to the foaming density and the like.

As the foaming gas (II), only one type may be used alone, or two or more types may be used.

<<< Polythiol (III) >>>
The polythiol (III) can react with an active energy ray-polymerizable functional group (unsaturated carbon bond) contained in the polyurethane raw material (I). By curing by such an enethiol reaction, it is possible to prevent oxygen inhibition and obtain a desired cured product.

Examples of the polythiol include an ester of a mercaptocarboxylic acid and a polyhydric alcohol, an aliphatic polythiol, and an aromatic polythiol.

Examples of the ester of mercaptocarboxylic acid and polyhydric alcohol include thioglycolic acid, mercaptopropionic acid and the like as mercaptocarboxylic acid, and ethylene glycol, propylene glycol, 1,4-butanediol and 1,6 as polyhydric alcohols. -Hexanediol, glycerin, trimethylolpropane, pentaerythritol, sorbitol and the like can be mentioned. Among these, esters of mercaptocarboxylic acid and polyhydric alcohol are preferable in terms of low odor, and specifically, for example, trimethylolpropane tris (3-mercaptopropionate) and pentaerythritol tetrakis (3). -Mercaptopropionate), tetraethylene glycol bis (3-mercaptopropionate), dipentaerythritol hexa (3-mercaptopropionate).

Examples of the aliphatic polythiol and the aromatic polythiol include ethanedithiol, propanedithiol, hexamethylenedithiol, decamethylenedithiol, tolylen-2,4-dithiol, and xylenedithiol.

As for polythiol (III), only one kind may be used alone, or two or more kinds may be used.

The number of functional groups of polythiol (III) is preferably 2.0 to 6.0. When a plurality of polythiols (III) are contained, the average number of functional groups is used.

When the effervescent composition contains polythiol (III), the SH-INDEX in the effervescent composition is preferably in the range of 0.5 to 1.5. In addition, SH-INDEX is "(content of polythiol (III) [g] x number of functional groups of polythiol (III)) / (molecular weight of polythiol (III) [g / mol] x active energy ray of prepolymer (A)". It is obtained by the amount of polymerizable functional groups [mol].

<<< Other Ingredients (IV) >>>
The effervescent composition may contain other components as long as it does not interfere with the effects of the present invention. Other components include solvents, dispersion media, catalysts, defoamers, foaming agents, foaming agents, polymerization initiators, light stabilizers, cross-linking agents, surfactants, thickeners, bubble nucleating agents, plasticizers, lubricants. , Known additive components such as colorants, antioxidants, oxygen scavengers, fillers, reinforcing agents, flame retardants, and surface treatment agents.

<<<<< Conductive polyurethane foam >>>>>
The structure of the conductive polyurethane foam is not particularly limited, and an appropriate structure may be used depending on the intended use.

When incorporating the conductive polyurethane foam into the image forming apparatus, it is preferable that the conductive polyurethane foam is a roll-shaped conductive foam roll. When the conductive polyurethane foam is a conductive foam roll, the roll inner diameter, roll outer diameter, urethane foam thickness, length, etc. of the conductive foam roll are determined by the shape of the image forming apparatus incorporating the conductive foam roll and the shape of the image forming apparatus. It can be changed as appropriate according to the size and the like.

Density of the conductive polyurethane foam is preferably 30~800kg / ^{m 3,} more preferably 50~500kg / ^{m 3.} The cell diameter of the urethane foam is preferably 1 to 300 μm.

The conductive polyurethane foam has a gel fraction of 90% or more, preferably 91.5% or more, more preferably 93% or more, and particularly preferably 95, in JIS K 6996 when the extraction solvent is acetone. % Or more.

According to the present invention, by blending a specific component, it is possible to obtain a conductive polyurethane foam having a high gel fraction as described above but not impairing hardness. Such a gel fraction can be appropriately adjusted by changing the amount of functional groups of each compound having active energy ray polymerization property in the effervescent composition and various production conditions (for example, reaction time). ..

The conductive polyurethane foam preferably has a 10% CLD of 200 kPa or less obtained by the following measuring method.
(Measurement method of 10% CLD)
According to JIS K 6400-2, the sample size is 50 mm × 50 mm × thickness 5 mm, 50% precompression is performed once, and then the CLD at 10% compression is measured.

The conductive polyurethane foam may be a closed cell foam or an open cell foam.

When the conductive polyurethane foam is a conductive foam roll, all of it may be urethane foam, or a part of it may be urethane foam, but at least the entire outer surface of the roll is made of urethane foam. Is preferable.

When a part of the conductive foam roll is made of urethane foam, the other materials used are not particularly limited and can be combined with metal, glass, ceramics, resin, rubber and the like.

<<<< Preferable example of a method for producing a conductive polyurethane foam >>>>>
The method for producing the conductive polyurethane foam preferably includes the following steps.
(Step 1: Preparation step)
Reacts with a polyol (a-1), a polyisocyanate (a-2), a conductive agent (a-3) having a functional group capable of reacting with an active hydrogen-containing group or active hydrogen, and an active hydrogen-containing group or active hydrogen. This is a step of preparing a polyurethane raw material (I) containing a prepolymer (A) synthesized from an active energy ray-polymerizable compound (a-4) having a functional group to be obtained and an active energy ray-polymerizable silicone (B). ..
(Step 2: Foaming step)
This is a step of obtaining a foamable composition by mechanically stirring the polyurethane raw material (I) and the foaming gas (II) in a nitrogen atmosphere and foaming them.
(Process 3: Coating process (arbitrary process))
This is a step that can be performed when the conductive polyurethane foam is a conductive foam roll, and is a step of applying the foamable composition on the roll shaft while rotating the roll shaft.
(Step 4: Irradiation step)
This is a step of irradiating the effervescent composition with active energy rays.

Further, a processing step for processing (cutting, polishing, etc.) the urethane foam obtained by the irradiation step may be provided.

The method for producing the conductive polyurethane foam is not limited to a mode in which each step is carried out in order as long as the effect of the present invention is not impaired, but also a form in which the order of some steps and another step is changed, or a part of the steps. It also includes a mode in which a step and another step (for example, a preparation step and a foaming step) are carried out at the same time, a form in which a part of the steps is repeatedly carried out, and the like.

Hereinafter, each step (preparation step, foaming step, coating step, irradiation step) will be described. Since each raw material is as described above, the description may be omitted.

<<< Preparation process >>
A known method can be used for the preparation step. For example, a predetermined amount of active energy ray-polymerizable silicone (B) can be added while stirring the prepolymer (A) to obtain a polyurethane raw material (I).

The preparation step may include a synthetic step of synthesizing the prepolymer (A). The synthesis step can be carried out according to a known method, for example, according to the following method.

An appropriate amount of polyisocyanate (a-2) is added to the container, and the mixture is stirred in a nitrogen atmosphere. A polyol (a-1), a conductive agent (a-3), and an active energy ray-polymerizable compound (a-4) are added dropwise thereto to obtain a prepolymer composition (a), and the prepolymer composition (a) is obtained. Is stirred for a predetermined time to complete the reaction, and the prepolymer (I) is obtained.

In the synthesis step, a catalyst may be added as needed to accelerate the reaction.

The catalyst is not particularly limited, and examples thereof include known catalysts such as tin-based catalysts, lead-based catalysts, other metal catalysts, amine-based catalysts, other acidic catalysts, and basic catalysts. One or more of these catalysts can be used.

The amount of the catalyst added is not particularly limited, but can be, for example, 0.001 to 5% by mass in the prepolymer composition (a).

Further, when the polythiol (III) is blended, it may be blended at the same time as the polyurethane raw material (I) is prepared, or may be blended after the polyurethane raw material (I) is prepared.

<<< Foaming process >>
In the foaming process, a so-called mechanical floss (mechanical flossing) method can be used.

The mechanical floss method is a method in which a gas in an atmosphere is mixed with a composition and foamed by stirring the composition with a stirring blade or the like. Therefore, the foaming step is usually carried out in a foaming gas (II) atmosphere.

As the stirring device, a stirring device generally used in the mechanical floss method can be used without particular limitation, and for example, a homogenizer, a dissolver, a mechanical floss foaming machine and the like can be used.

The foaming gas (II) forms bubbles (cells) in the urethane foam, and the amount of the foaming gas (II) mixed is determined according to the desired density of the urethane foam and the like. Just do it.

As the type of the foaming gas (II), as described above, dry air or an inert gas (for example, nitrogen, carbon dioxide, helium, argon, etc.) can be used. As the foaming gas (II), only one type may be used alone, or two or more types may be used.

In addition, in order to control unnecessary reactions of each composition, steps other than the foaming step may also be carried out in a dry air or an inert gas atmosphere.

<<< Coating process >>
The coating step is a step that can be performed when the conductive polyurethane foam is a conductive foam roll, and is a step of coating the foamable composition on the roll shaft while rotating the roll shaft.

In the coating process, the material of the roll shaft, the shape of the roll shaft, the rotation speed of the roll shaft, and the like are not particularly limited and may be known conditions.

Further, in the coating step, the means for supplying the foamable composition onto the roll shaft is not particularly limited, and the coating may be carried out by discharging the foamable composition onto the roll shaft. The coating may be carried out by bringing the roll shaft into contact with the layer containing the effervescent composition. Further, the supply rate of the effervescent composition can be changed as appropriate.

The coating process may be carried out a plurality of times to adjust the thickness of the effervescent composition.

<<< Irradiation process >>
The irradiation step is a step of irradiating the effervescent composition with active energy rays.

In the irradiation step, an active energy ray (preferably light) having a specific wavelength to which the active energy ray-reactive group (preferably a photoreactive functional group) reacts is irradiated to perform cross-linking. When a photopolymerization initiator or the like is used in combination, the wavelength at which the photopolymerization initiator reacts can be set.

The irradiation amount of the active energy ray may be set according to the composition and thickness of the effervescent composition.

When the coating process is carried out, the thickness of the urethane foam can be adjusted by changing the coating speed or the like in the above-mentioned coating process, but the coating process and the irradiation process are repeated a plurality of times to form a roll. It is also possible to increase the thickness.

When the coating step is carried out, a roll-shaped urethane foam can be obtained by pulling out the roll shaft from the urethane foam obtained through the irradiation step. The roll shaft may be supplied to the image forming apparatus as an integral part including the roll shaft and the urethane foam without pulling out the roll shaft from the urethane foam.

Further, the above-mentioned other component (IV) may be blended in any step before the irradiation step.

Further, in the above-mentioned coating step or irradiation step, heating may be carried out for the purpose of lowering the viscosity of the raw material or promoting curing. The heating temperature and the heating time are not particularly limited, and may be appropriately changed according to the purpose of heating and the raw materials used.

<<<<< Image forming device >>>>>
The electrophotographic image forming apparatus capable of incorporating the conductive polyurethane foam of the present invention is not particularly limited, but a laser printer is preferable. Since the conductive polyurethane foam of the present invention has low hardness and prevents bleeding of the conductive agent, it can be preferably used as a charging roll (roll body for charging a photosensitive drum) of a laser printer. ..

Examples will be shown below, and the present invention will be described in more detail. However, the present invention is not limited to this embodiment, and can be carried out in various embodiments with various modifications and improvements based on the knowledge of those skilled in the art.

＜＜ポリチオール（ＩＩＩ）＞＞
チオール３Ｆ：Ｌｅｃａｄ８０３ ＳＣ有機化学製
チオール４Ｆ：Ｌｅｃａｄ８０４ ＳＣ有機化学製
チオール６Ｆ：Ｌｅｃａｄ８０６ ＳＣ有機化学製
なお、チオール４Ｆは、以下に示したような構造を有する。

＜＜その他の成分＞＞
導電剤Ａ：１ＳＸ−１０９０、高分子イオン導電剤、大成ファインケミカル社製 <<< Raw materials >>
The raw materials used are as follows.
<< polyol (a-1) >>
PPG1000: Polypropylene glycol, molecular weight 1000
PPG2000: Polypropylene glycol, molecular weight 2000
PPG3000: Polypropylene glycol, molecular weight 3000
BEPG: Butyl ethyl propanediol << Polyisocyanate (a-2) >>
TDI: Toluene diisocyanate << Conductive agent (a-3) >>
Cation IN: Hydroxy group-containing quaternary ammonium salt-type cationic conductive agent, manufactured by NOF << Active energy ray-polymerizable compound (a-4) >>
HEMA: 2-Hydroxyethyl methacrylate << Active energy ray-polymerizable silicone (B) >>
Defoaming agent A: TEGORAD 2100, manufactured by Evonik The TEGORAD 2100 has a structure as shown below.

<< Polythiol (III) >>
Thiol 3F: Lecad803 SC Organic Chemistry Thiol 4F: Lecad804 SC Organic Chemistry Thiol 6F: Lecad806 SC Organic Chemistry Thiol 4F has the structure shown below.

<< Other ingredients >>
Conductive agent A: 1SX-1090, polymer ion conductive agent, manufactured by Taisei Fine Chemicals Co., Ltd.

<<< Manufacture of roll-shaped urethane foam >>
<< Example 1 >>
<Preparation process>
The prepolymer (A) was synthesized by mixing (a-1) to (a-4) at the blending amounts shown in Table 1. The synthesis was carried out under the following conditions.
1. 1. (A-1) and (a-2) were mixed and heated to 80 ° C. in a nitrogen atmosphere to react for 3 hours.
2. 2. After the temperature of the mixture was adjusted to 60 ° C., the component (a-3) was added and reacted for 1 h.
3. 3. The component (a-4) was added to the mixture and reacted for 1 h.
4. The temperature of the mixture was raised to 80 ° C., and additives such as a photopolymerization initiator, an antioxidant, and a light stabilizer were added so as to be in the range of 1 to 1.5 g in total with respect to 100 g of the prepolymer.
Next, the polyurethane raw material (I) was prepared by mixing the prepolymer (A) with the silicone (B) and the polythiol (III) at the blending amounts shown in Table 1. When the viscosity of the mixture was high, it was heated to about 80 ° C.
<Foam process, coating process, irradiation process>
Mechanical foaming was performed to prepare an effervescent composition. Mechanical foaming is carried out by mixing carbon dioxide in the atmosphere using an in-line homomixer. Chuck both ends of a Φ5 metal shaft with a rotating jig, and while rotating the shaft at a speed of 50 rpm, start the foamed raw material from one end of the shaft to the required length (L dimension, 250 mm). It was applied. The coating was applied so that the coating thickness was 1.5 mm.
After the coating was completed, the raw material was irradiated with UV by an irradiator (high pressure mercury lamp) and cured.
The irradiation conditions were 100 mW / cm ² or more and equivalent to 10,000 mJ / cm ² .
<Processing process>
Both ends of the cured product were cut to leave the required dimensions, and the surface of the cured product was polished using a cylindrical grinder to obtain a roller.

<< Examples 2 to 13, Comparative Examples 1 to 4 >>
Roll-shaped urethane foams according to Examples 2 to 13 and Comparative Examples 1 to 4 were obtained in the same manner as in Example 1 except that the raw materials used were changed to those shown in Table 1.

The obtained roll-shaped urethane foam had sufficient conductivity.

<<< Measurement of physical properties >>
The following physical property measurements were carried out. The measurement results are shown in Table 1.

<< Viscosity >>
The viscosity of the prepolymer (A) at 80 ° C. was measured according to JIS K 7117-2.

<< Gel fraction >>
For each roll-shaped urethane foam, the extraction solvent in JIS K 6996 was acetone, and the gel fraction was measured.

<< 10% CLD >>
According to JIS K 6400-2, each roll-shaped urethane foam was cut to a sample size of 50 mm × 50 mm × thickness 5 mm, 50% precompression was performed once, and then CLD at 10% compression was measured. ..

<<< Evaluation test >>
<< Image evaluation >>
An image evaluation test was conducted using each roll-shaped urethane foam. The evaluation method is as follows.
<Evaluation method>
As a bleed evaluation, a load of 500 g is applied to both ends of each roller acclimatized in an environment of 22 ° C. and 55% RH, and a continuous energization test is carried out at an applied voltage of 1000 V for 6 hours. This bleed-evaluated conductive roller was set in an image forming apparatus, and image evaluation was performed. When the conductive roller has bleeding, the bleeding substance adheres to other rollers and blurs in the image, and phenomena such as white spots and black spots are observed. Further, if the hardness of the conductive roller is high, the adhesion is lowered, and the image evaluation is similarly deteriorated. Based on the state of this image, the effect of suppressing bleeding of the roll-shaped urethane foam and the achievement of low hardness were evaluated.
<Evaluation criteria>
◯: No bleeding, white spots, black spots, etc. derived from the bleeding substance were observed.
X: Bleeding, white spots, black spots, etc. derived from the bleeding substance were observed.

Claims (11)

A urethane foam obtained by curing a foamable composition obtained by foaming a composition containing a polyurethane raw material (I) by a mechanical floss method.
The polyurethane raw material (I) contains a urethane prepolymer (A) having an ionic conductive group and an active energy ray-polymerizable functional group, and an active energy ray-polymerizable silicone (B).
The urethane foam is a conductive polyurethane foam having a gel fraction of 90% or more in which the extraction solvent of JIS K 6996 is acetone. The effervescent composition further comprises polythiol (III).
The conductive polyurethane foam according to claim 1, wherein the polythiol (III) has 2.0 to 6.0 functional groups. SH-INDEX ((content [g] of polythiol (III) × number of functional groups of polythiol (III)) / (molecular weight [g / mol] of polythiol (III) × prepolymer (A)) in the effervescent composition The conductive polyurethane foam according to claim 2, wherein the amount of active energy ray-polymerizable functional group [mol]) is in the range of 0.5 to 1.5. The conductive polyurethane foam according to any one of claims 1 to 3, wherein the urethane foam has a 10% CLD of 200 kPa or less measured by the following method.
(Measurement method of 10% CLD)
According to JIS K 6400-2, the sample size is 50 mm × 50 mm × thickness 5 mm, 50% precompression is performed once, and then the CLD at 10% compression is measured. The conductive polyurethane foam according to any one of claims 1 to 4, wherein the prepolymer (A) has a viscosity according to JIS K 7117-2 at 80 ° C. of 1 to 20 Pa · s. A member for an image forming apparatus made of the conductive polyurethane foam according to any one of claims 1 to 5. An image forming apparatus including the image forming apparatus member according to claim 6. A method for producing a conductive polyurethane foam.
Polyurethane (a-1), polyisocyanate (a-2), a conductive agent (a-3) having an active hydrogen-containing group or a functional group capable of reacting with active hydrogen and an ionic conductive group, and an active hydrogen-containing group. Alternatively, the polyurethane raw material (I) containing the prepolymer (A) synthesized from the active energy ray-polymerizable compound (a-4) having a functional group capable of reacting with active hydrogen and the active energy ray-polymerizable silicone (B). And the preparation process to prepare
A foaming step of obtaining a foamable composition by foaming the composition containing the polyurethane raw material (I) by a mechanical floss method.
Including an irradiation step of irradiating the effervescent composition with active energy rays.
The urethane foam is a method for producing a conductive polyurethane foam, which comprises a gel fraction of 90% or more using acetone as an extraction solvent in JIS K 6996. The conductive polyurethane foam is in the form of a roll and
The production method according to claim 8, further comprising a coating step of coating the foamable composition on the roll shaft while rotating the roll shaft after the adjustment step. The effervescent composition further comprises polythiol (III).
The production method according to claim 8 or 9, wherein the polythiol (III) has 2.0 to 6.0 functional groups. SH-INDEX ((content [g] of polythiol (III) × number of functional groups of polythiol (III)) / (molecular weight [g / mol] of polythiol (III) × prepolymer (A)) in the effervescent composition The production method according to claim 10, wherein the amount of active energy ray-polymerizable functional group [mol]) is in the range of 0.5 to 1.5.