JP2008020639A - Polyurethane foam roller, toner supply roller, and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyurethane foam roller which ensures good reactivity in manufacture, has good roller physical properties and reduces contamination of other components etc. due to an amine-based catalyst. <P>SOLUTION: The polyurethane foam roller is obtained by forming polyurethane foam on a metallic cylinder in a roller shape, wherein materials for the polyurethane foam comprises at least a polyol, a polyisocyanate, an amine-based catalyst, a foam stabilizer and an aqueous solution of a basic compound having a hydroxyl group, wherein the amine-based catalyst is used in an amount of 0.005-0.4 mass% based on the total material composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyurethane foam roller, particularly a polyurethane foam roller used in an image forming apparatus (including an electrophotographic apparatus) such as a copying machine, a printer, and a facsimile machine, and further includes a toner supply roller comprising the polyurethane roller and the toner supply The present invention relates to an electrophotographic apparatus in which a roller is incorporated.

  With the progress of electrophotographic technology, polyurethane foam members are attracting attention as image forming devices such as dry electrophotographic devices as parts for parts used for charging, development, transfer, toner supply, etc. It is used in the form of an elastic roller such as a charging roller, a developing roller, a transfer roller, or a toner supply roller (see, for example, Patent Document 1).

  For example, in a member having a polyurethane foam as an elastic layer, such as a roller, the polyurethane foam portion is usually foam-cured by mixing a polyol and a polyisocyanate together with various additives and a foaming aid as required. Manufactured.

  Conventionally, chlorofluorocarbons have been used as foaming agents for the production of polyurethane foam. However, the use of chlorofluorocarbons has been regulated due to problems such as global warming. ing.

  As such a production method, the use of water together with a polyol and a polyisocyanate has been proposed and has been put to practical use.

  Catalysts used in the production of such polyurethane foams include amine catalysts such as triethylenediamine, bis (dimethylaminoethyl) ether, N, N, N ′, N′-tetramethylhexanediamine, tin octylate and tin oleate. Organic metal catalysts such as dibutyltin dilaurate, dibutyltin diacetate, tetra-iso-propoxytitanium, tetra-N-butoxytitanium and tetrakis (2-ethylhexyloxy) titanium are known.

  Among these catalysts, amine-based catalysts have good compatibility with water, and amine-based catalysts have advantages such as toxicity and longer lifetime during premixing than organometallic catalysts. On the other hand, the amine catalyst needs to be used in a large amount, and the amount remaining in the urethane foam is large. Therefore, the amine catalyst remaining in the urethane foam is gradually volatilized. Therefore, when a conventional urethane foam using water as a foaming agent is used as an electrophotographic member, it contaminates other parts, toner, etc., and becomes a causative substance that deteriorates the image.

  Further, a conductive roller for an electrophotographic apparatus having a conductive polyurethane layer formed on the surface thereof is known in which a metal hydroxide is added to the polyurethane layer (see Patent Document 2).

  However, the metal hydroxide is used as a flame retardant, and the metal hydroxide is preferably magnesium hydroxide or aluminum hydroxide, and most preferably magnesium hydroxide. Magnesium hydroxide is preferably 5 phr to 50 phr, especially 10 phr to 30 phr in terms of physical properties and flame retardancy. If the amount of metal hydroxide is less than this range, sufficient flame retardancy cannot be obtained. It is stated.

  Furthermore, the effect of a metal hydroxide as a catalyst in a chemically foamed polyurethane foam using water as a foaming agent is not described and is unknown. Further, in the chemical foaming, when a strong base such as sodium hydroxide or potassium hydroxide is used as the metal hydroxide, the foaming reaction occurs rapidly and it is difficult to add 5 phr or more.

  Magnesium hydroxide and aluminum hydroxide are known to be hardly soluble in water (Non-Patent Document 1).

  And a metal layer selected from (A) a urethane resin and (B) aluminum, zinc, magnesium, and calcium, further comprising an elastic layer and a coating layer formed outside the elastic layer. There is known an intermediate transfer member characterized by containing an oxide or hydroxide of the above (see Patent Document 3). In Patent Document 3, the durability against ozone or nitrogen oxide is effectively improved by containing an oxide or hydroxide of a metal selected from aluminum, zinc, magnesium and calcium. Aluminum, zinc oxides and hydroxides are sparingly soluble in water, but are both amphoteric and acidic. Other metal oxides or hydroxides have low solubility in water (Non-Patent Document 1). Further, as in Patent Document 2, the metal hydroxides listed in Patent Document 3 are also unclear because the effects and effects on the formation of polyurethane foam by chemical foaming using water as a foaming agent have not been studied.

Addition of a metal hydroxide to a polyurethane resin is described in Patent Documents 2 and 3. However, in applications such as a toner supply roller, it is required to be a roller with uniform physical properties due to a uniform reaction, and sufficient uniformity cannot be achieved by adding the above hydroxide as a solid, and further investigation is required. Is required.
JP 2003-20318 A Japanese Patent No. 0329901 JP 2000-019855 A Iwanami Physical and Chemical Dictionary 4th Edition Iwanami Shoten

  Accordingly, an object of the present invention is to provide a polyurethane roller having good reactivity and good roller physical properties in production, and reduced contamination of the amine catalyst.

  The inventor has intensively studied to achieve the above object, and if a basic compound having a hydroxyl group is used as an aqueous solution, even if the amount of amine catalyst used is reduced, the reactivity and physical properties are not deteriorated. The inventors have found that a polyurethane foam roller having good performance can be obtained, and have completed the present invention.

  That is, the present invention relates to a polyurethane foam roller in which a polyurethane foam is formed in a roller shape on a core metal, wherein the polyurethane foam raw material is at least a polyol, a polyisocyanate, an amine catalyst, a foam stabilizer and a basic compound aqueous solution having a hydroxyl group. The polyurethane foam roller is characterized in that the amount of the amine catalyst used is 0.005% by mass or more and 0.4% by mass or less with respect to the total raw material composition.

  The basic compound having a hydroxyl group is preferably an alkali metal compound or an alkaline earth metal compound.

  The basic compound having a hydroxyl group is preferably potassium hydroxide, sodium hydroxide, lithium hydroxide, calcium hydroxide, strontium hydroxide or barium hydroxide.

  Furthermore, it is preferable that the usage-amount of the basic compound which has a hydroxyl group is 0.005 mass% or more and 0.5 mass% or less with respect to all the raw material compositions.

  According to another aspect of the present invention, the toner supply roller used in the electrophotographic apparatus is the above-mentioned polyurethane foam roller.

  Furthermore, the present invention is the electrophotographic apparatus, wherein the toner supply roller is the toner supply roller.

  Since the polyurethane foam roller of the present invention uses a small amount of an amine catalyst, it does not deteriorate physical properties brought about by the amine catalyst, and is good as a roller-shaped image forming apparatus member. For example, a charging member, a developing member It is particularly useful as a toner supply roller as a transfer member, toner supply member or cleaning member.

  The polyurethane foam roller of the present invention has a polyurethane foam layer formed on a core metal, and further, if necessary, a coating layer having various functions is provided on the polyurethane foam. The polyurethane foam roller can be used as a roller-shaped image forming apparatus member such as a charging member, a developing member, a transfer member, a toner supply member, and a cleaning member.

  For example, the polyurethane foam layer is formed on the cored bar as follows.

  First, polyol and polyisocyanate as main components, at least a basic compound having a hydroxyl group, a foaming agent such as water, an amine catalyst for controlling the urethanization reaction, and a foam stabilizer for stabilizing the foamed cell were added. The raw material composition is prepared by mixing and stirring the composition.

  Next, the raw material composition is subjected to foam molding, and the obtained polyurethane foam is cut into a roller shape, and a core metal is press-fitted into the center to form a polyurethane foam layer around the core metal. Alternatively, the raw material composition is poured into a cylindrical mold in which a metal core is previously disposed, and heated and foamed in the metal mold to form a polyurethane foam layer on the metal core.

  In the present invention, it is important to use a basic compound having a hydroxyl group in combination with an amine catalyst. Thereby, even if the amount of amine catalyst used is reduced, the urethanization reaction can be sufficiently promoted.

  The basic compound having a hydroxyl group needs to be used as an aqueous solution in order to be uniformly dispersed in the raw material composition and to exert a urethanization catalytic action. As a basic compound having such a hydroxyl group, a strong basic compound is preferable because it is effective when used in a small amount. For example, as the strongly basic compound, an alkali metal compound or an alkaline earth metal compound having a hydroxyl group can be raised. In addition, although the same effect is acquired by increasing the usage-amount also with a weak basic compound, the problem that a physical property tends to deteriorate generate | occur | produces.

  The basic compound is used in the form of an aqueous solution so that it can be uniformly dispersed in the polyurethane material. As described above, the basic compound is preferably an alkali metal compound or an alkaline earth metal compound, and easily dissolves in water with potassium hydroxide, sodium hydroxide, lithium hydroxide, calcium hydroxide, water. Strontium oxide or barium hydroxide is preferred. These basic compounds may be used alone or in any combination.

  The basic compound is used in an amount of from 0.005% by mass to 0.5% by mass, preferably from 0.01% by mass to 0.3% by mass in the total raw material composition. In addition, when it exceeds 0.5 mass%, physical properties, such as a compression residual distortion, will deteriorate, and when it is less than 0.005 mass%, it will become difficult to fully reduce the usage-amount of an amine catalyst.

  In the present invention, any amine catalyst can be used as long as it is used as a urethanization catalyst. For example, triethylenediamine, bis (dimethylaminoethyl) ether, N, N, N ′, N′-tetramethylhexanediamine, N-ethylmorpholine, N, N-dimethylaminohexanol and the like are preferable. These amine catalysts may be used alone or in any combination. The amount of the amine catalyst used is preferably 0.005% by mass or more and 0.4% by mass or less. If the amount used exceeds 0.4% by mass, the amine catalyst from the polyurethane foam layer will bleed and cause image defects. If it is less than 0.005% by mass, it will be difficult to function as an amine catalyst. It becomes.

  There is no restriction | limiting in particular as a polyol used by this invention, It can select and use suitably from conventionally well-known various polyols. That is, polyethylene adipate, polybutylene adipate, polyhexylene adipate, copolymer of ethylene adipate and butylene adipate, polyester polyol such as dimer acid polyol, castor oil polyol, polycaprolactone polyol, and polyoxyalkylene glycol Ether polyol, polymer polyol (trade name: manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) and the like can be used. In addition, it is preferable to use the polyol whose molecular weight is 2000-10000 individually or in mixture. That is, when the molecular weight is less than 2,000, the crosslinking density becomes too high, and the physical properties of the resulting polyurethane foam tend to be lowered. On the other hand, if it exceeds 10,000, the viscosity of the polyol itself is high and the reactivity and workability tend to deteriorate. Of these polyols, it is preferable to use a polyether polyol because a polyurethane foam excellent in wet heat resistance can be obtained. Furthermore, a polyether polyol in which ethylene oxide (EO) is grafted at 5 mol% or more on the terminal is preferable because it is excellent in reactivity. Further, a prepolymer in which a terminal obtained by reacting a polyisocyanate with a polyol in advance is a hydroxyl group may be used.

  The polymer polyol (trade name) is obtained by polymerizing and modifying an ethylenically unsaturated monomer (acrylonitrile, styrene, methyl methacrylate, vinylidene chloride, etc.) in a polyether polyol. When this polymer polyol is used as a part of the polyol, it is preferable because air permeability can be improved without lowering the wet heat durability of the polyurethane foam.

  Moreover, there is no restriction | limiting in particular also as polyisocyanate, It can select and use suitably from conventionally well-known various polyisocyanate. Polyisocyanates include polymethylene polyphenyl polyisocyanate (polymeric MDI), diphenylmethane diisocyanate (MDI), toluene polyisocyanate (TDI) and other polyisocyanates, hexamethylene diisocyanate and other aliphatic polyisocyanates, and isophorone diisocyanate and other alicyclics. Polyisocyanate and its derivatives can be used in combination. Furthermore, you may use the prepolymer which the terminal which reacted polyol and polyisocyanate beforehand is an isocyanate group.

  The mixing ratio of these polyisocyanate and polyol is not particularly limited, but it is usually preferable that the NCO index is 60 to 120, preferably 70 to 105.

  In the present invention, water is usually used as a foaming agent. Water reacts with the polyisocyanate to form polyurea and generates carbon dioxide gas, which becomes a foaming agent. As for the usage-amount of water, 0.1-10 mass parts is preferable with respect to 100 mass parts of all the polyols, More preferably, it is 0.1-5 mass parts. In addition to the water, hydrocarbons (such as cyclopentane), carbon dioxide gas, and other blowing agents may be used.

  In the present invention, a foam stabilizer is used in order to stabilize the foamed cell in forming the polyurethane foam. Examples of the foam stabilizer include water-soluble polyether siloxane from polydimethylsiloxane and EO / PO copolymer, sodium salt of sulfonated ricinoleic acid, and a mixture of these with a polysiloxane / polyoxyalkylene copolymer. Of these, water-soluble polyether siloxanes from polydimethylsiloxane and EO / PO copolymers are preferred. The amount used is suitably 0.01 to 5 parts by mass with respect to 100 parts by mass of the total polyol. If it is less than 0.01 parts by mass, the foamed cells are likely to be non-uniform, and appearance defects are likely to occur. On the other hand, if it exceeds 5 parts by mass, problems such as seepage tend to occur.

  As other auxiliaries, a crosslinking agent, a flame retardant, a colorant, an ultraviolet absorber, an anti-aging agent, an antioxidant, a conductivity imparting agent, and the like are used as necessary.

  The method for producing the polyurethane foam is not particularly limited and may be a conventional method. An example is as follows. First, after mixing the above polyol, polyisocyanate, amine catalyst, foam stabilizer, water, basic compound having a hydroxyl group, and other auxiliaries, the polyurethane foam is obtained by heating and reaction curing. It is done. The temperature and time for mixing the raw materials are not particularly limited, but the mixing temperature is usually in the range of 10 to 90 ° C, preferably 20 to 60 ° C, and the mixing time is usually 1 second to 10 minutes, preferably Is about 3 seconds to 1 minute. Moreover, when making it heat-react and hardening, the various members which consist of a polyurethane foam can be produced by making it foam by a conventionally well-known method.

  The polyurethane foam roller of the present invention is produced by cutting out the polyurethane foam obtained in this way into a roll shape and inserting a metal core made of iron plated or stainless steel. Or it manufactures by performing the said foaming in the metal mold | die provided with the metal core.

  Depending on the application, a conductivity-imparting agent may be added to the raw material composition, or the outside may be painted with a conductive, semiconductive, or insulating paint.

  The use of the polyurethane foam roller of the present invention is not particularly limited, but a roller-shaped member for an image forming apparatus, such as a charging member, a developing member, a transfer member, a toner supply member, a cleaning member, etc. Can be used. In particular, it is suitable as a toner supply roller.

  An explanatory view of an example of an electrophotographic image forming apparatus (electrophotographic apparatus) using the polyurethane foam roller of the present invention as a toner supply roller is shown in FIG.

  A developing roller 2 holding toner for developing the electrostatic latent image as a toner image is provided in the vicinity of the photoreceptor 1 that forms an electrostatic latent image on the surface by exposure. A toner supply roller 3 is provided on the developing roller 2 to scrape the remaining toner developed from the photoreceptor 1 and to supply new toner. Further, a toner regulating blade 4 that makes the toner supplied from the toner supply roller 3 uniform thickness contacts the developing roller 2. The toner image on the photoconductor 1 is transferred to a recording medium 8 inserted between the transfer roller 5 provided facing the photoconductor 1 and the photoconductor 1, and the recording medium 8 on which the toner image is transferred is fixed. The image is sent to an apparatus (not shown) and an image is fixed on the recording medium 8. On the other hand, a cleaning blade 6 for scraping and removing a small amount of toner remaining on the photoreceptor 1 after the toner image is transferred is in contact with the photoreceptor 1. Further, thereafter, a charger 7 (in the figure, a power failure roller) for applying a uniform charge to the photosensitive member 1 is in contact. These are arranged in the order shown in FIG. 1, and the photoreceptor 1, the developing roller 2, and the toner supply roller 3 rotate in the directions shown in FIG. 1 to achieve their functions.

  Here, an example in which the toner supply roller is the polyurethane foam roller of the present invention is shown. However, the polyurethane foam roller of the present invention can be used as a developing roller, a transfer roller, a charging roller, a cleaning roller, or the like by appropriately modifying the polyurethane foam layer, its surface, or the like.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

  The polyurethane foam raw materials used in the following examples and comparative examples are shown.

1) Polyol Actol EP-950 (trade name), polyether polyol manufactured by Mitsui Chemicals Polyurethane Co., Ltd., OH number 34.

2) Polyisocyanate Cosmonate TM50 (trade name), polyisocyanate manufactured by Mitsui Chemicals Polyurethanes, NCO = 39.8%.

3) A foam stabilizer, SRX-274C (trade name), a silicone foam stabilizer manufactured by Toray Dow Corning Co., Ltd.

4) Amine-based catalyst / catalyst 1: TOYOCAT-ET (trade name), bis (dimethylaminoethyl) ether, manufactured by Tosoh Corporation ・ Catalyst 2: TOYOCAT-MR (trade name), N, N, N ′, N ′ -Tetramethylhexanediamine, manufactured by Tosoh Corporation

5) Hydroxyl-containing basic compound, sodium hydroxide: manufactured by Kishida Chemical Co., Ltd., reagent grade

Examples 1-4, Comparative Examples 1-2
(Preparation of raw material composition for polyurethane foam layer)
An aqueous solution prepared by dissolving 100 parts by mass of a polyol with sodium hydroxide as a basic compound having a hydroxyl group in an amount shown in Table 1 in 2.5 parts by mass of water, an amount of an amine catalyst shown in Table 1, and a foam stabilizer 1.0 A part by mass was added and mixed by stirring to obtain a polyol component liquid. The polyol component liquid and 30.4 parts by mass of polyisocyanate were each adjusted to 25 ° C.

  On the other hand, the cream time and rise time, which are indicators of the reaction rate of the raw material composition for the polyurethane foam layer, were measured as follows. That is, at room temperature (25 ± 3 ° C.), the above-mentioned polyol component liquid corresponding to 50 g of polyol was weighed into a cup having an internal volume of 500 ml, added with polyisocyanate (NCO index 85), and stirred at 2000 to 3500 rpm for 5 seconds. Thereafter, the time until the reaction mixture liquid became cloudy in the form of a cream from the start of mixing / stirring (cream time) and the time until foaming reached the maximum height by foaming (rise time) were measured. These measured values are shown in Table 1.

(Manufacture of polyurethane foam rollers)
An inside of a SUS cylindrical mold provided with an iron cored bar having a diameter of 6 mm and a length of 30 cm and nickel chemical plating was prepared, and the temperature was adjusted to 50 ° C. In this, the polyol component and polyisocyanate which were temperature-controlled at 25 degreeC were respectively weighed and sampled, mixed for 5 seconds, and injected. Then, it was foam-cured for 20 minutes in a thermostatic bath heated to 50 ° C. to produce a polyurethane foam roller having an outer diameter of 16 mm. The length of the polyurethane foam layer was 22 cm, and the density of the polyurethane foam layer was 0.1 g / cm ³ .

When the polyurethane foam roller was taken out from the mold after completion of foam curing, the deformation or restoration of the polyurethane foam layer was observed, and the cured state was evaluated as follows.
○: Curing progressed sufficiently and no problem.
(Triangle | delta): Although hardening is progressing, it is somewhat insufficient.
X: It was not hardened | cured enough and distortion was observed in the polyurethane foam layer at the time of taking out.

  Next, the compression residual strain ratio (Cs) of the polyurethane foam layer of the obtained polyurethane foam roller was measured as shown in FIG. The results are shown in Table 1 together with the cured state.

A metal sleeve 14 having a diameter of 16 mm is brought into contact with the polyurethane foam layer 11 of the polyurethane foam roller 17. Next, the exposed portion of the metal core 10 of the polyurethane foam roller 17 and the metal sleeve 14 are held by the fixture 15 in a state where the polyurethane foam layer 11 is displaced (compressed) by 1.5 mm at both ends. In this state, after placing under 40 ° C. and 95% RH for 72 hours, taking out and removing the fixture, 30 minutes later, the degree of restoration of the displacement of the polyurethane foam layer was measured, and the compression residual strain ratio ( Cs) (%) is calculated.
Cs = {(t ₀ −t ₁ ) /1.5} × 100
In the formula, t ₀ and t ₁ are the radius (mm) of the first molded product and the radius (mm) of the molded product after the test, respectively.

  Note that the right side of FIG. 2B is a side view showing a state in which the metal sleeve 14 is in contact with the left side, and the left side view is a side view showing the state of distortion of the polyurethane foam roller 17 after being opened. It is.

The obtained polyurethane foam roller is incorporated as a toner supply roller of a process cartridge of an electrophotographic image forming apparatus “Laser Shot LBP-1310” (trade name) manufactured by Canon Inc., and has an environment with a temperature of 40 ° C. and a humidity of 95%. The sample was left for 30 days and then placed in an environment of a temperature of 25 ° C. and a humidity of 55% for 12 hours, and then a solid black image was output continuously for 10 sheets. The image unevenness coming from the bleeding of the amine-based catalyst appearing in the solid black image obtained was visually observed and evaluated according to the following criteria. The results are shown in Table 1.
○: No problem Δ: Image unevenness was initially observed, but the image unevenness disappeared immediately and there was no problem.
X: Image unevenness was observed even on the 10th sheet.

  Examples 1 to 3 were polyurethane foam rollers having good reactivity and physical properties similar to those of Comparative Example 1 that did not contain a basic compound having a hydroxyl group. In addition, Example 4 was slightly insufficiently cured. In Example 3, the wet heat compression permanent deformation was slightly inferior. On the other hand, Comparative Example 2 was not sufficiently cured, and the shape was deformed after demolding.

  In addition, the basic compound which has a hydroxyl group should just be water-soluble, and although the sodium hydroxide was used in the said Examples 1-4, it cannot be overemphasized that this is only an example.

It is explanatory drawing which shows an example of the electrophotographic apparatus of this invention. It is explanatory drawing of the method of measuring a compression residual distortion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developing roller 3 Toner supply roller 4 Regulating blade 5 Transfer roller 6 Cleaning blade 7 Charging roller 8 Recording medium 10 Core metal 11 Polyurethane foam layer 14 Metal sleeve (φ16 mm)
15 Fixing tool 16 Strain remaining part 17 Polyurethane foam roller

Claims (6)

In a polyurethane foam roller in which a polyurethane foam is formed on a mandrel in a roller shape,
The polyurethane foam raw material consists of a basic compound aqueous solution having at least a polyol, a polyisocyanate, an amine catalyst, a foam stabilizer and a hydroxyl group,
A polyurethane foam roller, wherein the amount of the amine catalyst used is 0.005 mass% or more and 0.4 mass% or less with respect to the total raw material composition.   2. The polyurethane foam roller according to claim 1, wherein the basic compound having a hydroxyl group is an alkali metal compound or an alkaline earth metal compound.   3. The polyurethane foam roller according to claim 2, wherein the basic compound having a hydroxyl group is potassium hydroxide, sodium hydroxide, lithium hydroxide, calcium hydroxide, strontium hydroxide or barium hydroxide.   4. The urethane according to claim 1, wherein the amount of the basic compound having a hydroxyl group is 0.005% by mass or more and 0.5% by mass or less based on the total raw material composition. Foam roller.   The toner supply roller used for an electrophotographic apparatus is the polyurethane foam roller of any one of Claims 1-4, The toner supply roller characterized by the above-mentioned.   An electrophotographic apparatus, wherein the toner supply roller is the toner supply roller according to claim 5.

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