JP7073736B2 - Manufacturing method of sponge roller and sponge roller - Google Patents

Description

The present invention relates to a sponge roller and a method for manufacturing a sponge roller. More specifically, the sponge roller and the sponge roller have a small cell diameter, a high rate of continuous foaming, and a suppression of the shape change of the foamed elastic layer due to thermal expansion. Regarding the manufacturing method of.

Various image forming devices using an electrophotographic method are adopted in printers such as laser printers and video printers, copiers, facsimiles, and multifunction devices thereof. Various image forming devices include rollers having a shaft body and an elastic layer formed on the outer peripheral surface thereof, for example, a cleaning roller, a charging roller, a developing roller, a transfer roller, a pressure roller, and a paper feed transfer roller. , Equipped with various rollers such as fixing rollers. Among these rollers, for example, a cleaning roller, a paper feed transport roller, a fixing roller, a pressure roller, and the like often improve the functions of each roller.

For example, the fixing roller and the pressure roller may reduce the cell diameter of the foamed elastic layer in order to prevent printing defects and improve durability. Patent Document 1 is a silicone rubber composition obtained by mixing a high molecular weight silicone rubber with a rubber composition obtained by mixing a pre-expanded resin microballoon with a low molecular weight silicone rubber for the purpose of improving durability. Discloses a silicone rubber sponge roller that cures silicone rubber by heating it at a temperature lower than the softening point of the resin microballoon.

Further, for example, the pressure roller allows the cells of the foamed elastic layer to communicate with other cells existing in the vicinity in order to prevent the cells of the foamed elastic layer from expanding due to heat and deforming the foamed elastic layer. In some cases. Patent Document 2 has a continuous foam structure in which the foaming elastic layer has a continuous foaming ratio of 90% or more for the purpose of discharging the gas in the cell of the foamed elastic layer at a high temperature in the pressure roller for fixing. The pressurizing roller for fixing is disclosed. Further, Patent Document 3 describes a non-adhesive layer made of a fluororesin formed on the outer peripheral surface of the foamed elastic layer for the purpose of discharging the gas in the cell of the foamed elastic layer at a high temperature in the pressure roller. A pressure roller is disclosed in which a needle is pierced in a range including a paper passing portion and a plurality of perforations for breathing of the foamed elastic layer of the pressure roller are provided.

International Publication No. 2013/005613 Japanese Unexamined Patent Publication No. 2004-70159 Japanese Patent No. 3808926

Here, in the sponge roller having the foamed elastic layer, when the cell diameter of the foamed elastic layer is reduced, the continuous foaming ratio is lowered, and the gas in the cell of the foamed elastic layer cannot be efficiently discharged, so that when the sponge roller is used. There is a problem that the thermal expansion rate of the is large.

Therefore, an object of the present invention is to provide a sponge roller having a small cell diameter, a high rate of continuous foaming, and suppressing a change in the shape of the foamed elastic layer due to thermal expansion, and a method for manufacturing the sponge roller.

The inventors of the present invention have conducted diligent research in order to solve the above problems. As a result, the above-mentioned problems can be solved by adjusting the continuous foaming ratio in a sponge roller having a foamed elastic layer formed of a mirable type silicone rubber, an unexpanded microballoon, a cross-linking agent, and a chemical foaming agent. The present invention was completed. Specifically, the present invention provides the following.

(1) A sponge roller having a shaft body and a foamed elastic layer formed on the outer peripheral surface of the shaft body, wherein the foamed elastic layer is a mirable type silicone rubber, an unexpanded microballoon, a cross-linking agent, and a chemical. A sponge roller formed of a foaming agent and having a continuous foaming ratio of 6% or more and 90% or less in the foamed elastic layer.

(2) The sponge roller according to (1), wherein the asker C hardness of the foamed elastic layer is 20 or more and 80 or less.

(3) The sponge roller was put into a dryer heated to 150 ° C., the outer diameter of the roller was measured every 10 minutes from the start of heating to 50 minutes later, and the thickness of the foamed elastic layer before heating was 10 When the coefficient of thermal expansion of the foamed elastic layer measured every minute is calculated, the coefficient of thermal expansion of the foamed elastic layer 50 minutes after the start of heating is subtracted from the coefficient of thermal expansion of the foamed elastic layer 10 minutes after the start of heating. The sponge roller according to (1) or (2), wherein the value is 0.01 or more and 1.2 or less.

(4) A step of arranging a rubber composition on the outer peripheral surface of the shaft body and vulcanizing it while heating to obtain a roller original body having a foamed elastic body, and mounting a shock absorber on the outer peripheral surface of the roller original body. , Each of the three narrow pressure tubes arranged at the apex of the triangle compresses the total thickness of the foamed elastic body and the buffer tube in the radial direction by 30% or more and 65% or less. The method for manufacturing a sponge roller according to any one of (1) to (3), which comprises a step of narrowing the body with the narrow pressure tube and rotating the body to form the foamed elastic layer.

The sponge roller of the present invention uses a miraculous silicone rubber, an unexpanded microballoon, and a chemical foaming agent to form the foamed elastic layer. In the foamed elastic layer, since the continuous foaming ratio of the cells having a small cell diameter formed by the unexpanded microballoons is adjusted to be high, it is possible to prevent the foamed elastic layer from expanding due to heat. From the above, according to the present invention, it is possible to provide a sponge roller having a small cell diameter, a high continuous foaming ratio, and suppressing a change in the shape of the foamed elastic layer due to thermal expansion.

It is explanatory drawing which shows the sponge roller which shows one Example of this invention. It is explanatory drawing which shows an example of the image forming apparatus which incorporates the sponge roller which shows one Embodiment of this invention into a fixing apparatus. It is a schematic diagram which shows the pressing device suitablely used in the process of forming a foam elastic layer in the manufacturing method of the sponge roller in one Example of this invention. FIG. 3 is a cross-sectional view taken along the line AA of FIG.

<Sponge roller>
As shown in FIG. 1, the sponge roller 1 as an example of the present invention has a shaft body 2 also referred to as a core metal, and a foamed elastic layer 3 formed on the outer peripheral surface of the shaft body 2. Reference numeral 4 denotes a sleeve formed on the surface of the foamed elastic layer 3 as needed, and for example, a fluororesin layer or the like may be formed.

The shaft body 2 is a long columnar body usually made of iron, aluminum, stainless steel, brass or the like, which is a so-called core metal. The shaft body 2 is adjusted to an appropriate diameter and axial length according to the image forming apparatus 30 to be mounted.

When the sponge roller 1 is incorporated in the image forming apparatus 30, the shaft body 2 usually has a diameter of 5.0 mm or more and 40 mm or less, and the shaft length from one end to the other end is usually 150 mm or more and 1000 mm or less. ..

[Foam elastic layer]
The foamed elastic layer 3 is formed of a miraculous silicone rubber, a cross-linking agent, an unexpanded microballoon, and a chemical foaming agent.

(Mirable silicone rubber)
Mirable type silicone rubber is similar to natural rubber and unvulcanized compound rubber of ordinary synthetic rubber in the state before curing, and can be plasticized and mixed with a kneading roll machine or a closed type mixer or the like. It is a silicone rubber compound (silicone rubber composition).

A suitable mirabable silicone rubber contains the following components (A) to (E).

(A) Organopolysiloxane R ¹ _a SiO _{(4-a) / 2} (I) with a degree of polymerization of 100 or more represented by the following average composition formula (I)
(In the formula, R ¹ represents the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number from 1.95 to 2.05.)
(B) Reinforcing silica having a specific surface area of 50 m ² / g or more by the BET adsorption method (C) Alkoxysilane represented by the following general formula (II) R ² mSi (OR ³ ) _4-m (II)
(In the formula, R ² is an independently hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, R ³ is the same or different unsubstituted or substituted alkyl group, and m is 0, 1, 2 or 3)
(D) Water (E) Hexaorganodisilazane represented by the following general formula (III) R ⁴ ₃ SiNHSiR ⁴ ₃ (III)
(In the formula, R ⁴ represents the same or different monovalent hydrocarbon group.)

Specific examples of the miraculous silicone rubber in the present invention include KE-571-U, KE-1571-U, KE-951-U, KE-541-U, and KE-551-U manufactured by Shin-Etsu Chemical Co., Ltd. U, KE-561-U, KE-961T-U, KE-1541-U, KE-1551-U, KE-941-U, KE-971T-U and the like can be used.

(Uninflated microballoon)
In the sponge roller 1 of the present invention, an unexpanded microballoon is used to form the foamed elastic layer 3. Examples of the uninflated microballoon in the present invention include a non-inflated resin microballoon. As a result, by making the cells of the foamed elastic layer 3 into fine cells, it is possible to prevent printing defects and to obtain the foamed elastic layer 3 with improved durability.

As the resin microballoon, one using a thermoplastic resin for the outer shell is preferably used. Examples of the thermoplastic resin constituting the outer shell include vinylidene chloride / acrylonitrile copolymer, methyl methacrylate / acrylonitrile copolymer, and metaacrylonitrile / acrylonitrile copolymer. It is preferable to use a resin microballoon in which the softening temperature of the resin to be the outer shell is within an appropriate range according to the curing temperature of the liquid silicone rubber. Further, examples of the included evaporative substance include hydrocarbons such as butane and isobutane.

The unexpanded resin microballoons suitable for the present invention are commercially available as "Matsumoto Microsphere F Series" (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.), "Expansel Series" (manufactured by Expansel Co., Ltd.) and the like.

(Chemical foaming agent)
In the sponge roller 1 of the present invention, a chemical foaming agent is used to form the foamed elastic layer 3. The chemical foaming agent in the present invention may be any foaming agent conventionally used for forming the foaming elastic layer 3. Examples thereof include sodium bicarbonate, ammonium carbonate and the like as inorganic foaming agents, and organic foaming agents include. Examples thereof include organic azo compounds such as diazoamino derivatives, azonitrile derivatives and azodicarboxylic acid derivatives. Among the organic azo compounds, azodicarboxylic acid amide, azobis-isobutyronitrile and the like are preferably used. In particular, azobis-isobutyronitrile can be preferably used.

It is preferable to adjust the blending amount of the unexpanded microballoons and the blending amount of the chemical foaming agent to the amounts as described in the description of the production method according to the present invention.

(Crosslinking agent)
In the sponge roller 1 of the present invention, a cross-linking agent is used to form the foamed elastic layer 3. By using a cross-linking agent, volatile gas of unexpanded microballoons is generated before the start of cross-linking of the miraculous silicone rubber, and a ventilation part is formed between the cells at the same time as the cells are formed. The layer 3 can be formed, and the thermal expansion rate of the foamed elastic layer 3 can be made good.

As the cross-linking agent, an organic peroxide cross-linking agent may be used, an addition reaction cross-linking agent may be used, or both an organic peroxide cross-linking agent and an addition reaction cross-linking agent may be used in combination.

The organic peroxide cross-linking agent is not particularly limited, but for example, benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2, 5-Dimethyl-2,5-bis (t-butylperoxy) hexane, di-t-butylcumyl peroxide, paramethylbenzoyl peroxide and the like can be used. When only the organic peroxide cross-linking agent is used, the blending amount of the organic peroxide cross-linking agent is preferably 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the miraculous silicone rubber. It is more preferable that the amount is 5 parts by mass or more and 5 parts by mass or less. In general, when an organic peroxide cross-linking agent is used, the cell diameter tends to be large, but in the present invention, as will be described later, an unexpanded microballoon which tends to form fine cells is used. Therefore, the cells formed in the foamed elastic layer 3 become fine as a whole.

The organic peroxide cross-linking agent may be used alone or in combination of two or more. The decomposition temperature of the organic peroxide cross-linking agent is preferably higher than the foaming start temperature of the unexpanded microballoon and the decomposition temperature of the chemical foaming agent.

The addition reaction cross-linking agent is not particularly limited, but for example, an addition reaction catalyst, an addition reaction type cross-linking agent having two or more SiH groups (SiH bonds) in one molecule, or the like can be used. can. When an addition reaction catalyst is used, platinum black, secondary platinum chloride, platinum chloride acid, reaction product of platinum chloride acid and monovalent alcohol, complex of platinum chloride acid and olefins, platinum bisacetoacetate, palladium-based catalyst, etc. Can be mentioned. The blending amount of the addition reaction catalyst can be the amount of the catalyst. When an addition reaction type cross-linking agent having two or more SiH groups (SiH bonds) in one molecule is used, examples thereof include organohydrogenpolysiloxane. The blending amount of the addition reaction type cross-linking agent having two or more SiH groups (SiH bonds) in one molecule is usually 0.5 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the mirable type silicone rubber. can do. When both the organic peroxide cross-linking agent and the addition reaction cross-linking agent are used in combination, the physical properties such as strength and strain of the obtained sponge roller 1 can be further improved.

[Continuous foam rate]
The foam elastic layer 3 has a cell (hereinafter, referred to as a continuous cell or a continuous bubble) that is in contact with or communicates with another cell existing in the vicinity. This continuous cell can also be said to be a cell in which the wall of the independent cell, which will be described later, is damaged and communicates with another cell existing in the vicinity through the broken wall. In addition to the continuous cell, the foamed elastic layer 3 is a cell that does not contact or communicate with other cells existing in the vicinity (hereinafter, referred to as an independent cell) as long as the object of the present invention is not impaired. May have. The shape of the cell is not particularly limited, and may be, for example, a substantially spherical shape, an elliptical shape, an amorphous shape, or a tubular shape in which a plurality of cells communicate with each other.

In the continuous cell, it is preferable that a plurality of cells communicate with other cells existing in the vicinity thereof through the fracture wall to form a three-dimensional communication passage in the foam elastic layer 3. When the continuous cell forms a three-dimensional communication passage in this way, even if the sleeve 4 is provided on the outer peripheral surface of the foamed elastic layer 3, the gas existing in the cell is foamed elastic via the communication passage. The gas can be efficiently discharged from both ends of the layer 3, and the gas existing outside the sponge roller 1 can be taken into the cell of the foamed elastic layer 3 via this communication passage. As a result, even if the temperature of the sponge roller 1 reaches a high temperature, the air in the foamed elastic layer 3 can be efficiently discharged from the foamed elastic layer 3, so that the gas existing in the cell of the foamed elastic layer 3 can be discharged. It does not expand in the confined state, and it is possible to effectively prevent the pressure and hardness of the foamed elastic layer 3, particularly the central portion thereof, from increasing. On the other hand, even if the temperature of the sponge roller 1 drops from a high temperature to a low temperature, gas can be taken into the cell from the outside of the foamed elastic layer 3, so that the pressure and hardness of the foamed elastic layer 3, especially the central portion thereof, are increased. It can be effectively prevented from becoming low. The continuous cell not only exists near the surface of the foamed elastic layer 3, but also exists inside the foam elastic layer 3, for example, near the outer peripheral surface of the shaft body 2, and forms a three-dimensional communication path. And, it is preferable in that the characteristics can be well expressed when the sponge roller 1 is used. Whether or not the continuous cell exists inside the foamed elastic layer 3 can be confirmed by visually observing the cut surface obtained by cutting the foamed elastic layer 3.

The continuous foam ratio of the foamed elastic layer 3 can be calculated as follows. First, a test piece is prepared by cutting out all or a part of the foamed elastic layer 3. The mass W (g) and density D (g / cm ³ ) of the test piece are measured according to a conventional method, and the volume V (cm ³ ) of the test piece is calculated by W / D. Then, the test piece is immersed in water filled in a container arranged in the decompression chamber, and the pressure in the decompression chamber is reduced to 30 mmHg or less for 2 minutes until no bubbles appear from the test piece, and the decompression is released. Let stand at normal pressure for 5 minutes. Then, the test piece is taken out from the water, the water adhering to the test piece is wiped off, the mass _{Wi (g) of the test piece after immersion is measured, and the mass W w (} g) of the water absorbed by the test piece is W. Calculated by _i -W. Assuming that the density of water is 1 (g / cm ³ ), W _w is equal to the volume V _w (cm ³ ) of water absorbed by the test piece. Further, the density D _c (g / cm3) of the rubber composition forming the foamed elastic layer 3 is measured in advance according to a conventional method. From this, the continuous foaming ratio (%) of the foamed elastic layer 3 is _{ (Wi − W) / specific density of water} / {(1-D / D _c ) × (W / D)} × 100 (%). It can be calculated by the formula of.

The continuous foaming ratio of the foamed elastic layer 3 is 6% or more and 90% or less, preferably 20% or more and 80% or less, and more preferably 30% or more and 70% or less. As a result, even when heat is applied when the sponge roller 1 is used and the gas in the cell of the foam elastic layer 3 thermally expands, the gas can be efficiently discharged from the foam elastic layer 3 via the continuous cell. Therefore, the shape change of the foamed elastic layer 3 due to thermal expansion can be suppressed.

[Asker C hardness]
The foamed elastic layer 3 preferably has an asker C hardness of 20 or more and 80 or less, and more preferably 30 or more and 70 or less. In the sponge roller 1 of the present invention, the Asker C hardness on the surface of the foamed elastic layer 3 has a difference of 1 or less between both ends in the axial direction. The small difference in the Asker C hardness of the foamed elastic layer 3 in the sponge roller 1 means that even when the pressurized foamed elastic layer 3 is deformed by thermal expansion, it is uniformly deformed and the bias of the stress distribution is small. It is preferable because it has the advantage of becoming.

[Coefficient of thermal expansion]
In the present invention, while the cell diameter of the foamed elastic layer 3 is small, the continuous foaming ratio of the foamed elastic layer 3 is maintained high, so that when the sponge roller 1 is heated, the air inside the cell is exposed to the outside. It is easily released and tends to suppress thermal expansion due to heating. In general, a sponge roller having a low continuous foaming ratio shows an increase in volume at the initial stage of heating, but this volume increase tends to disappear with the passage of time due to the air permeability of the silicone rubber itself. Since the sponge roller 1 of the present invention has a high continuous foaming ratio, the volume increase of the foamed elastic layer 1 is small at the initial stage of heating, the coefficient of thermal expansion can be suppressed to a low level, and the shape of the foamed elastic layer 3 changes. It can be suppressed.

The sponge roller 1 was put into a dryer heated to 150 ° C., the outer diameter of the roller was measured every 10 minutes from the start of heating to 50 minutes later, and every 10 minutes from the thickness of the foamed elastic layer 3 before heating. When the measured coefficient of thermal expansion of the foamed elastic layer 3 was calculated, the value obtained by subtracting the coefficient of thermal expansion of the foamed elastic layer 3 50 minutes after the start of heating from the coefficient of thermal expansion of the foamed elastic layer 3 10 minutes after the start of heating was calculated. , 0.01 or more and 1.2 or less, and more preferably 0.4 or more and 0.8 or less. When the coefficient of thermal expansion is within the above range, the shape change of the foamed elastic layer 3 due to thermal expansion can be suppressed. More specifically, the sponge roller 1 is put into a dryer heated to 150 ° C., heated for 10 minutes, the sponge roller 1 is taken out from the dryer, the outer diameter of the roller is measured, and the foam elasticity before heating is measured. The coefficient of thermal expansion is calculated from the thickness of the layer 3, and the coefficient of thermal expansion in heating every 10 minutes for a total of 50 minutes is calculated.

[Crown amount]
The sponge roller 1 is put into a dryer heated to 150 ° C., and the amount of crown is every 10 minutes from the start of heating to 50 minutes after the start of heating (the value obtained by subtracting the minimum outer diameter of the central portion from the maximum outer diameter of both ends). The difference between the crown amount before the start of heating and the crown amount 50 minutes after the start of heating is preferably 0.01 mm or more and 0.1 mm or less, and 0.03 mm or more and 0.07 or less. Is more preferable. As a result, it is possible to provide the sponge roller 1 in which the shape change of the foamed elastic layer 3 due to thermal expansion is suppressed and paper wrinkles are less likely to occur.

[Dimensions of elastic layer, etc.]
The foamed elastic layer 3 is formed in a columnar shape on the outer peripheral surface of the shaft body 2, and the thickness of the foamed elastic layer 3 is usually preferably 0.5 mm to 30 mm, more preferably 1 mm to 15 mm. The shape of the sponge roller 1 formed on the outer peripheral surface of the shaft body 2 is a shape that gradually increases the thickness of the foamed elastic layer 3 from both ends of the shaft body 2 toward the center of the shaft body 2 in the axial direction of the shaft body 2. , (Crown shape), a shape that gradually increases the thickness of the foamed elastic layer 3 from the center of the shaft body 2 toward both ends of the shaft body 2 (reverse crown shape), a straight shape, etc., but paper wrinkles. The inverted crown shape is preferable in terms of suppressing the occurrence of.

The foamed elastic layer 3 is a dispersant such as a low molecular weight siloxane ester, silanol, for example, diphenylsilanediol, and a heat resistance improver such as iron oxide, cerium oxide, and iron octylate, as long as the object of the present invention can be achieved. , Various carbon functional silanes that improve adhesiveness and moldability, halogen compounds that impart flame retardancy, and the like may be contained within a range that does not impair the object of the present invention.

The sponge roller 1 according to the present invention can be incorporated into, for example, a fixing device of an image forming apparatus 30.

<Image forming device>
An example of the image forming apparatus 30 incorporating the fixing apparatus provided with the sponge roller 1 according to the present invention will be described with reference to FIG.

As shown in FIG. 2, the image forming apparatus 30 includes a rotatable image carrier 31 on which an electrostatic latent image is formed, for example, a photoconductor, and a charging means 32 arranged around the image carrier 31. For example, a charging roller, an exposure means 33, a developing means 40, a transfer means 34, for example, a transfer roller, a cleaning means 37, and a fixing means 35 on the downstream side in the transport direction of the recording body 36 are provided. The developing means 40 is formed basically in the same manner as the conventional developing means, and specifically, as shown in FIG. 2, the developing agent 42 is supplied to the developing agent accommodating portion 41 and the image carrier 31. It includes a developer carrier 44, a developer supply means 43 that supplies the developer 42 to the developer carrier 44, and a developer regulating member 45 that charges the developer 42.

As the fixing device in the image forming apparatus 30, for example, the sponge roller 1 of the present invention can be used for the pressure roller 56 of the fixing means 35. That is, as shown in the cross section of FIG. 2, the fixing means 35 is arranged in the vicinity of the fixing roller 53 and the fixing roller 53 in the housing 50 having the opening 52 through which the recording body 36 is passed. The belt support roller 54, the endless belt 55 wound around the fixing roller 53 and the endless belt support roller 54, the pressure roller 56 that presses against the fixing roller 53 via the endless belt 55, and the endless belt 55 in non-contact manner. It is provided with a heating means (not shown) for heating the fixing roller 53 from the outside via the endless belt 55, and the fixing roller 53 and the pressurizing roller 56 come into contact with each other or come into contact with each other via the endless belt 55. It is a pressure heat fixing device that is rotatably supported so as to be in pressure contact.

The endless belt support roller 54 may be any roller normally used in the image forming apparatus 30, and for example, an elastic roller or the like may be used. The endless belt 55 may be a belt formed in an endless shape with, for example, a resin such as polyamide or polyamide-imide, and its thickness and the like can be appropriately adjusted to suit the fixing means 35. The pressure roller 56 is pressed against the fixing roller 53 via an endless belt 55 by an urging means (not shown) such as a spring. In this fixing means 35, the sponge roller 1 according to the present invention can be mounted as a pressure roller 56. As the heating means, a radiant heating method using a halogen heater, a reflector or the like, a direct contact heating method in which a heater or the like is directly contacted to heat the heating, an induction heating method or the like is adopted. This heating means is a member having substantially the same length as the axial length of the fixing roller 53, and may be arranged on any of the fixing means 35, but as shown in FIG. 2, the surface of the fixing roller 53 It is preferable that the fixing rollers 53 are arranged substantially in parallel with each other at regular intervals. A heating coil is used for the induction heating method, and the heating coil is usually a ferromagnet such as ferrite and has typical shapes used for switching power supplies, such as I-type, E-type, and U-type. Etc., and the lead wire is wound. When the recording body 36 passes between the endless belt 55 and the pressure roller 56 under pressure contact, the developer 42 (electrostatic latent image) transferred to the recording body 36 is fixed by being heated at the same time as the pressurization. be able to.

The image forming apparatus 30 operates as follows. First, in the image forming apparatus 30, the image carrier 31 is uniformly charged by the charging means 32, and an electrostatic latent image is formed on the surface of the image carrier 31 by the exposure means 33. Next, the developer 42 is supplied from the developing means 40 to the image carrier 31, and the electrostatic latent image is developed, and the developer image is conveyed on the recorder 36 which is conveyed between the image carrier 31 and the transfer means 34. Is transferred to. The recording body 36 is conveyed to the fixing means 35, and the developer image is fixed to the recording body 36 as a permanent image. In this way, an image can be formed on the recording body 36. When the sponge roller 1 according to the present invention is adopted as the pressurizing roller 56 in the fixing means 35 and the image forming apparatus 30, the cell diameter is small, but the continuous foaming ratio is high, and the shape change of the foamed elastic layer due to thermal expansion is suppressed. It can be the image forming apparatus 30.

<Manufacturing method of sponge roller>
The sponge roller 1 according to the present invention has a step of arranging a rubber composition on the outer peripheral surface of the shaft body 2 and vulcanizing it while heating to obtain a roller original body 5 having a foamed elastic body 6, and a roller original body 5. A buffer tube 65 is attached to the outer peripheral surface of the ring, and each of the three narrow pressure tube bodies 62, 63, 64 arranged at the apex of the triangle is in the radial direction with respect to the total thickness of the foamed elastic body 6 and the buffer tube 65. It is manufactured by a method for manufacturing a sponge roller 1 having a step of forming a foamed elastic layer 3 by narrowing the pressure with narrow pressure tubes 62, 63, 64 so as to compress the foam elastic layer 3 by 30% or more and 65% or less. be able to.

First, in the production method according to the present invention, a mirable type silicone rubber, a cross-linking agent, an unexpanded microballoon, and a chemical foaming agent are blended to obtain a rubber composition. For example, 1.0 part by mass or more and 5.0 parts by mass or less of the cross-linking agent with respect to 100 parts by mass of the miraculable silicone rubber, and 0.2 parts by mass or more of the unexpanded microballoon with respect to 100 parts by mass of the miraculable silicone rubber. A rubber composition is obtained by blending 10 parts by mass or less and 0.2 parts by mass or more and 10 parts by mass or less of the chemical foaming agent with respect to 100 parts by mass of the miraculous silicone rubber. In order to improve the continuous foaming ratio, the ratio of the amount of the unexpanded microballoons to the amount of the chemical foaming agent is preferably 3: 5 to 5: 3. It is more preferably 5: 4, and particularly preferably 1: 1. The amount of the unexpanded microballoon and the chemical foaming agent to be blended is 7.5 with respect to 100 parts by mass of the miraculous silicone rubber. It is more preferable that the amount is 10 parts by mass or more and 10 parts by mass or less. Further, in order to improve the continuous foaming ratio, it is preferable that the blending amount of the cross-linking agent is 1.0 part by mass or more and 2.5 parts by mass or less with respect to 100 parts by mass of the miraculous silicone rubber.

The types of unexpanded microballoons, cross-linking agents, chemical foaming agents, etc. have already been described.

The mixing method is not particularly limited, and for example, an unexpanded microballoon, a chemical foaming agent, and a cross-linking agent are sequentially or at once charged into a miraculable silicone rubber under normal temperature and pressure, and uniformly used in a stirrer, a kneader, or the like. Examples include a method of mixing with silicone. In this way, the step of preparing the rubber composition is completed.

Various additives can be included in the rubber composition. As various additives, for example, auxiliary agents such as chain extenders, catalysts, dispersants, foaming agents, antioxidants, antioxidants, fillers, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers. , Heat resistance improver, flame retardancy improver, acid receiving agent, heat conductivity improver, mold release agent, solvent and the like. These various additives may be commonly used additives or may be specially used additives depending on the intended use.

The rubber composition is, for example, for several minutes to several hours, preferably 5 It can be obtained by kneading at room temperature or heating for 1 minute or more and 1 hour or less.

Next, the obtained rubber composition is placed on the outer peripheral surface of the shaft body 2 for forming the sponge roller 1. For example, it can be heat-molded and placed by continuous heat-molding by extrusion molding, pressing, mold molding by injection, or the like.

After the rubber composition is arranged or formed in a columnar shape on the outer surface of the shaft body 2, the columnar rubber composition, in other words, the columnar molded body is vulcanized (heat-cured) while heating the shaft body 2 together. Then, the roller original body 5 having the foamed elastic body 6 can be obtained. The average of large-diameter cells after foaming depends on the conditions for performing this heat vulcanization, for example, the types of unexpanded microballoons and chemical foaming agents and their addition amounts, the types of cross-linking agents and their addition amounts, and the heating temperature. The cell diameter and the average cell diameter of the small diameter cell can be adjusted within a predetermined range.

When the rubber composition is heated and vulcanized, it is particularly preferable to heat the rubber composition as follows. That is, the primary vulcanization is heated from 100 ° C. to 300 ° C., especially 150 ° C. to 250 ° C. for 5 to 30 minutes, and then the secondary vulcanization is carried out from 180 ° C. to 250 ° C., especially from 200 ° C. to 230 ° C. from 1 hour. It is preferable to heat for 10 hours. When heated multiple times in this way, the expansion of the unexpanded microballoon, the decomposition of the chemical foaming agent, the curing of the miraculous silicone rubber, the elimination of residual low molecular weight siloxane, and the thermal contraction of the expanded microballoon are controlled as necessary. It is possible and preferable. Further, by performing the heating operation a plurality of times in this way, it is possible to prepare a composite cell having a small-diameter cell derived from an unexpanded microballoon and a large-diameter cell derived from a chemical foaming agent. The average cell diameter of the large-diameter cell is not smaller than the average cell diameter of the small-diameter cell.

The heating required for vulcanization can be performed in a heating furnace such as an infrared heating furnace or a hot air furnace, a heating machine such as a dryer, or the like.

The roller bulk material 5 thus obtained may be further subjected to a polishing step. The polishing step is a step of adjusting the shape of the foamed elastic body 6 formed on the outer peripheral surface of the shaft body 2 to a crown shape, an inverted crown shape, a straight shape, or the like.

Next, as shown in FIGS. 3 and 4, a shock absorber 65 is attached to the outer peripheral surface of the roller original body 5, and the three narrow pressure tubes 62, 63, and 64 arranged at the apex of the triangle are foamed. The roller original body 5 is narrowly compressed by the narrow compression tubes 62, 63, 64 so as to be compressed by 30% or more and 65% or less in the radial direction with respect to the total thickness of the elastic body 6 and the shock absorber 65, and rotated. It is used in the step of forming the foamed elastic layer 3. As a result, the coefficient of thermal expansion of the foamed elastic layer 3 can be further suppressed. The compressibility is preferably 40% or more and 60% or less from the viewpoint of eliminating damage or breakage of the foamed elastic layer 3 and suppressing the coefficient of thermal expansion.

For example, the foamed elastic body 6 preferably has a thickness of 2 mm or more and 20 mm or less. Further, the buffer tube 65 is preferably made of solid rubber from the viewpoint of efficient transmission of the pressing force by the narrow pressure tube bodies 62, 63, 64, respectively, and buffering of the excessive pressing force, and the buffer tube 65 is preferably made of solid rubber. The JIS A hardness is preferably 20 or more and 75 or less. Further, from the viewpoint of accurately adjusting the compressibility of the foamed elastic body 6, the wall thickness of the shock absorber 65 is preferably 5% or more and 150% or less with respect to the thickness of the foamed elastic body 6, and is preferably 10 mm or less. Is preferable. The shaft hole and inner diameter of the shock absorber 65 are preferably selected according to the shape of the foamed elastic body 6, and the shaft hole has a shape corresponding to the outer diameter of the foamed elastic body 6 of the roller bulk material 5. It is preferable in that the foamed elastic body 6 can be uniformly compressed. For example, when the foamed elastic body 6 has a so-called "crown shape", it is preferable that the inner diameter of the shock absorber 65 gradually increases from both ends to the central portion and the shaft hole has a so-called "crown shape". When the body 6 has a so-called "reverse crown shape", it is preferable that the inner diameter of the shock absorber 65 gradually decreases from both ends to the central portion and the shaft hole has a so-called "reverse crown shape". The outer shape of the shock absorber 65 may be a so-called "straight shape", a so-called "crown shape" or a so-called "reverse crown shape", and is appropriately selected depending on the shape of the foamed elastic body 6 of the roller bulk material 5 and the partial compression amount. Will be done.

For example, as the pressing device 60 used in the step of forming the foamed elastic layer 3, as shown in FIGS. 3 and 4, the first narrow pressure tube body 62 and the second narrow pressure tube whose axes C1 and C2 are located in the same plane. At least one of a third narrow pressure tube body 64 in which the body 63 and the axis C3 are located in a plane perpendicular to the same plane, and a first narrow pressure tube body 62, a second narrow pressure tube body 63, and a third narrow pressure tube body 64. Is arranged on the outer peripheral surface of the foamed elastic body 6 included in the rotation mechanism 61 for rotating the roller original body 5, which is narrowed by the first narrow pressure tube body 62, the second narrow pressure tube body 63, and the third narrow pressure tube 64. It is preferable to use a pressing device 60 having a shock absorber 65.

Further, the sleeve 4 may be provided on the outer surface of the sponge roller 1 thus obtained, or may be covered with a tube, for example, a fluororesin tube to provide a fluororesin layer. For the coating with the fluororesin tube, for example, a pressure insertion method in which the sponge roller 1 is compressed under pressure and inserted into the fluororesin tube, a decompression insertion method in which the fluororesin tube is compressed under reduced pressure and inserted into the fluororesin tube, This can be done by a reduced pressure diameter expansion method or the like in which the fluororesin tube is expanded in the radial direction under reduced pressure and the sponge roller 1 is inserted into the inside thereof.

The method for manufacturing the sponge roller 1 and the sponge roller 1 according to the present invention is not limited to the above embodiments, and various changes can be made as long as the object of the present invention can be achieved.

For example, in the sponge roller 1, the foamed elastic layer 3 has a single-layer structure, but in the present invention, it may have a multi-layer structure of two or more layers.

The image forming apparatus 30 is an electrophotographic image forming apparatus, but the image forming apparatus 30 is not limited to the electrophotographic system, and may be, for example, an electrostatic type image forming apparatus. Further, the image forming apparatus 30 is a monochrome image forming apparatus in which only the monochromatic developer 42 is accommodated in the developing means 40, but the image forming apparatus 30 is not limited to the monochrome image forming apparatus and is a color image forming apparatus. It may be. Examples of the color image forming apparatus include a 4-cycle type color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier to an intermediate transfer body, and a plurality of image carriers provided with developing means for each color. Examples thereof include a tandem type color image forming apparatus in which the images are arranged in series on an intermediate transfer body and a transfer transfer belt. The image forming apparatus 30 is, for example, an image forming apparatus such as a copying machine, a facsimile, or a printer.

Further, in the fixing means 35 and the image forming apparatus 30, a one-component developer is preferably used as the developer 42, but a two-component developer containing a toner and a carrier such as iron or nickel is also used. can do.

<Examples 1 to 3, Comparative Example 1 and Comparative Example 2>
In Examples 1 to 3 and Comparative Examples 1 and 2, the base rubber material shown in Table 1, the cross-linking agent shown in Table 1, the catalyst shown in Table 1, and the catalyst shown in Table 1 are shown. The unexpanded microballoon and the chemical foaming agent shown in Table 1 were sufficiently kneaded with two rolls in the blending amounts shown in Table 1 to obtain a rubber composition.

In the rubber compositions used in Examples 1 to 3 and Comparative Examples 1 and 2, the base rubber material is a miraculous silicone rubber manufactured by Shinetsu Chemical Industry Co., Ltd. under the trade name KE-551U, and the catalyst is Shinetsu. The unexpanded microballoon is a platinum catalyst manufactured by Kagaku Kogyo Co., Ltd. under the trade name C-25A, the unexpanded microballoon is the trade name Matsumoto Microsphere manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., and the chemical foaming agent is manufactured by Otsuka Chemical Co., Ltd. The product name is AIBN of the AZO series. As the cross-linking agent, C-25B manufactured by Shin-Etsu Chemical Co., Ltd. was used.

Next, the shaft body on which the primer layer was formed and the rubber composition were integrally separated by an extrusion molding machine, and in Examples 1 to 3 and Comparative Examples 1 and 2, an infrared heating furnace (IR heating furnace) was used. The rubber composition is primary vulcanized by heating at 225 ° C. for 17 minutes using Was produced. The circumferential surface of this roller body was polished at high speed with a metal grindstone by a polishing machine manufactured by Mizuguchi Seisakusho Co., Ltd.

Next, a shock absorber is attached to the outer peripheral surface of the roller original body, and each of the three narrow pressure tubes arranged at the apex of the triangle is 60% in the radial direction with respect to the total thickness of the foamed elastic body and the shock absorber. The original roller was compressed with a narrow pressure tube and rotated to form a foamed elastic layer, and a sponge roller was obtained.

The sponge rollers obtained in Examples 1 to 3 and Comparative Examples 1 and 2 have an inverted crown shape with an outer diameter of 30 mm and an axial length of 340 mm, and have a continuous foam ratio, an Asker C hardness, and a thermal expansion coefficient. And the amount of crown were measured and summarized in Table 1.

1 Sponge roller 2 Shaft body 3 Foam elastic layer 4 Sleeve 5 Roller base 6 Foam elastic body 30 Image forming device 31 Image carrier 32 Charging means 33 Exposure means 34 Transfer means 35 Fixing means 36 Recording body 37 Cleaning means 40 Developing means 41 Developer storage 42 Developer 43 Developer supply means 44 Developer support 45 Developer control member 50 Housing 52 Opening 53 Fixing roller 54 Endless belt support roller 55 Endless belt 56 Pressurizing roller 60 Pressing device 61 Rotating mechanism C1, C2, C3 Axis line 62 1st narrow pressure tube 63 2nd narrow pressure tube 64 3rd narrow pressure tube 65 Buffer tube

Claims (3)

A sponge roller having a shaft body and a foamed elastic layer formed on the outer peripheral surface of the shaft body.
The foamed elastic layer is formed of a miraculous silicone rubber, an unexpanded microballoon, a cross-linking agent and a chemical foaming agent.
The continuous foam ratio in the foamed elastic layer is 6% or more and 90% or less .
The sponge roller is put into a dryer heated to 150 ° C., the outer diameter of the roller is measured every 10 minutes from the start of heating to 50 minutes later, and every 10 minutes from the thickness of the foamed elastic layer before heating. When the measured coefficient of thermal expansion of the foamed elastic layer was calculated, the value obtained by subtracting the coefficient of thermal expansion of the foamed elastic layer 50 minutes after the start of heating from the coefficient of thermal expansion of the foamed elastic layer 10 minutes after the start of heating was calculated. , -1.2 or more and -0.1 or less, sponge roller. The sponge roller according to claim 1, wherein the asker C hardness of the foamed elastic layer is 20 or more and 80 or less. A step of arranging a rubber composition on the outer peripheral surface of the shaft body and vulcanizing it while heating to obtain a roller bulk material having a foamed elastic body.
A shock absorber is attached to the outer peripheral surface of the roller original body, and each of the three narrow pressure tubes arranged at the apex of the triangle is 30 in the radial direction with respect to the total thickness of the foamed elastic body and the shock absorber. 30 . Production method.

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