JP6113622B2 - Method for producing silicone rubber sponge and method for producing silicone foam roller - Google Patents

Description

  The present invention relates to a method for producing a silicone rubber sponge and a method for producing a silicone foam roller, and more particularly to a method for producing a silicone rubber sponge having open cells and a method for producing a silicone foam roller provided with the silicone rubber sponge.

Rubber sponges having a porous structure are suitably used for various rollers for image forming apparatuses, sponges for cleaning, sponges for absorbing fluids such as water and oil, and printing materials.
Such a rubber sponge can be produced by, for example, a foam molding method using a foaming agent, a method using hollow fine particles, or an elution method for eluting pre-mixed soluble particles. For example, as a “method for forming the conductive compressible layer 23” of an image transfer roll for an image forming apparatus, Patent Document 1 states that “a foaming agent is blended in a synthetic rubber compound for forming a compressible layer, Foam molding method to form a compressible layer having cells by foaming during vulcanization of rubber, hollow microsphere mixing method to form independent cells by blending hollow microspheres instead of foaming agent, or water A compressible layer having cells by eluting the powder, e.g. sodium chloride, sugar, etc., which can be dissolved in an eluent such as methanol, into a synthetic rubber compound and eluting the powder after vulcanization The powder elution method is known. "

More specifically, as a method using a microballoon, Patent Document 2 discloses a “pressure roller having an elastic layer dispersedly containing voids formed by a resin microballoon around a core metal” The elastic layer is formed by heating the liquid silicone rubber containing the inflated resin microballoon on the core metal at a temperature lower than the softening point of the resin microballoon to cure the liquid silicone rubber. It is described that the void portion is generated by destruction ”(claim 1 and the like).
Patent Document 3 uses “a water-in-oil emulsion composition capable of producing a silicone elastomer porous body having uniform fine cells (bubbles) without causing a foaming phenomenon” to use “a copying machine, a laser printer, etc. "Substantially closed-cell type silicone elastomer porous body" that can be used for "imaging parts and the like" is described.
In addition to various rollers for image forming apparatuses, for example, Patent Document 4 relating to “sponge rubber printing body” as a printing material includes “rubber, water-soluble fine powder, vulcanizing agent, filler, and fiber length of 0.2 to 2 mm. A sponge rubber printing body having open cells obtained by kneading the staple of organic synthetic fiber to obtain a master batch, vulcanizing it and washing away the water-soluble fine powder ”is described (Claim 1). .

JP 2005-24902 A Japanese Patent No. 3658305 Japanese Patent No. 4638714 Japanese Patent No. 3647110

  It is an object of the present invention to provide a method for producing a silicone rubber sponge and a method for producing a silicone foam roller capable of producing a silicone rubber sponge having open cell cells, a silicone foam roller provided with the silicone rubber sponge.

Means for solving the problems are as follows:
(1) 50 to 200 parts by weight of water-soluble particles and 0.1 to 5 parts by weight of water are mixed with 100 parts by weight of the silicone rubber component contained in the liquid silicone rubber composition and the liquid silicone rubber composition. A preparation step for preparing the mixture, a molding step for molding the mixture, a curing step for curing the obtained molded body, and an elution step for eluting the water-soluble particles from the obtained cured body. A method for producing a silicone rubber sponge,
(2) The method for producing a silicone rubber sponge according to (1) above, wherein the silicone rubber sponge has an open cell ratio of 65 to 98%,
(3) The method for producing a silicone rubber sponge according to (1) or (2), further including a recovery step of recovering the water-soluble particle-forming substance eluted in the elution step,
(4) The molding step is a method for producing a silicone rubber sponge according to any one of (1) to (3), which is a tubular molding step of molding the mixture into a tubular shape.
(5) A method for producing a silicone foam roller, comprising an insertion step of inserting a shaft body into a through hole in a tubular silicone rubber sponge produced by the production method according to (4).

  Since both the manufacturing method of the silicone rubber sponge and the manufacturing method of the silicone foam roller according to the present invention have a preparation process, a molding process, and an elution process, almost all of the water-soluble particles present in the molded body are quickly removed. Can be eluted. Therefore, according to this invention, the manufacturing method of the silicone rubber sponge which can manufacture the silicone rubber sponge which has an open cell, and the silicone foam roller provided with this silicone rubber sponge, and the manufacturing method of a silicone foam roller can be provided.

FIG. 1 is a schematic diagram showing a durability test apparatus that is suitably used for carrying out a durability test of an elastic roller in the embodiment.

  First, the silicone rubber sponge produced by the method for producing a silicone rubber sponge according to the present invention and the silicone rubber sponge provided in the silicone foam roller produced by the method for producing a silicone foam roller according to the present invention will be described. This silicone rubber sponge has a porous structure in which silicone rubber forms a skeleton having a three-dimensional network structure. In this porous structure, there are mainly open cells that are in contact with or in communication with other bubbles (also referred to as cells) in the vicinity, and in contact with other cells in the vicinity in addition to the open cells. There may be closed cells that do not or communicate with each other. In the silicone sponge, the majority of the bubbles only need to be open cells. For example, the open cell rate (sometimes referred to as open cell rate) of the bubbles is preferably 65 to 98%, particularly 75 to 98%. preferable. When the bubble open ratio is within the above range, when used for a roll to be heated, there is little change in the outer diameter due to thermal expansion when heated, and a large number of nips can be applied, so the image quality is stable, Printing speed can also be increased. In addition, since the burden on the rubber is reduced, the effect of increasing durability can be obtained.

The bubble open ratio can be calculated as follows. First, a test piece is prepared by cutting out all or part of the silicone rubber sponge. The mass W (g) and density D (g / cm ³ ) of this test piece are measured according to a conventional method, and the volume V (cm ³ ) of the test piece is calculated by W / D. Next, the test piece is immersed in water filled in a container disposed in the vacuum chamber, the inside of the vacuum chamber is depressurized until no bubbles appear from the test piece, and when no bubbles appear from the test piece, Release the reduced pressure and let stand at normal pressure for 24 hours. Next, 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 Ww (g) of the water absorbed by the test piece is Wi-W. Calculated by Note that the volume Vw (cm ³ ) of water absorbed by the test piece is equal to Ww when the density of water is 1 (g / cm ³ ). On the other hand, the density Dc (g / cm ³ ) of the silicone rubber composition forming the silicone rubber sponge is measured in advance according to a conventional method, and the theoretical volume Vc (cm of the silicone rubber sponge formed with this silicone rubber composition is measured. ³ ) is calculated by W / Dc, and the total volume Vb (cm ³ ) of open cells formed in the silicone rubber sponge is calculated by V-Vc. Then, the open cell ratio (%) of the silicone rubber sponge is calculated from the volume Vw of water absorbed by the test piece and the total volume Vb of open cells calculated in this way (Vw / Vb) × 100 ( %), That is, (Ww / Vb) × 100 (%).

The bubbles are not particularly limited, and may be, for example, substantially spherical, may be an ellipsoidal shape or an indefinite shape, or may be a tubular shape in which a plurality of cells are communicated. The average cell diameter of the open cells is usually almost the same as the average particle diameter of the water-soluble particles described later, preferably 80 to 500 μm, particularly preferably 100 to 400 μm. When the average cell diameter is within the above range, the silicone rubber sponge toner pressure bonding is excellent, and an effect that the image quality can be improved can be obtained.
The silicone rubber sponge preferably has an Asker C hardness of 10 to 40, particularly preferably 20 to 30. When the Asker C hardness is within the above range, an effect that a large number of nips can be applied is obtained.

The silicone rubber sponge has an appropriate shape depending on the application, and examples thereof include a plate shape, a block shape, a tubular shape, an annular shape, a prismatic shape, and a cylindrical shape.
The method of manufacturing a silicone foam roller according to the method of manufacturing a silicone foam roller according to the present invention includes a tubular silicone rubber sponge having a cross-sectional shape that is generally circular or elliptical and having a shaft hole. Since this silicone rubber sponge satisfies the above characteristics, it is suitably used for various rollers mounted on the image forming apparatus, in particular, a fixing roller, a pressure roller, a developing roller, a recording medium conveying roller, a cleaning roller, and the like.

Next, a method for producing a silicone rubber sponge and a method for producing a silicone foam roller according to the present invention (hereinafter, both production methods may be collectively referred to as a production method according to the present invention) will be described together.
The method for producing a silicone rubber sponge according to the present invention includes the steps described above, and in the method for producing a silicone foam roller according to the present invention, the molding step is a step of molding the mixture into a tubular shape.

In the production method according to the present invention, the liquid silicone rubber composition, 50 to 200 parts by mass of water-soluble particles, and 0.1 to 0.1 parts of water with respect to 100 parts by mass of the silicone rubber component contained in the liquid silicone rubber composition. A step of preparing a mixture by mixing 5 parts by mass is performed.
The liquid silicone rubber composition to be prepared includes (A) an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and (B) a hydrogen atom bonded to silicon atoms in one molecule. An organohydrogenpolysiloxane containing at least two, (C) an inorganic filler having an average particle diameter of 1 to 30 μm and a bulk density of 0.1 to 0.5 g / cm ³ , and (D) an addition reaction catalyst. And an addition-curable liquid silicone rubber composition.

  As said (A) organopolysiloxane, the compound shown by the following average compositional formula (1) is suitable.

R ¹ _a SiO _{(4-a) / 2} (1)
Here, R ¹ in the average composition formula (2) is the same or different monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and a is It is a positive number in the range of 1.5 to 2.8, preferably 1.8 to 2.5, more preferably 1.95 to 2.02.
Examples of R ¹ include alkyl groups, aryl groups, aralkyl groups, alkenyl groups, and hydrocarbon groups in which some or all of these hydrogen atoms are substituted with halogen atoms, cyano groups, or the like. At least two of R ¹ are alkenyl groups, particularly vinyl groups, and preferably 90% or more are methyl groups. Specifically, the alkenyl group content in the organopolysiloxane is 1.0 × 10 ^{−6 to} 5.0 × 10 ⁻³ mol / g, particularly 5.0 × 10 ^{−6 to} 1.0 × 10 ^−. It is preferably ³ mol / g.

The degree of polymerization of the organopolysiloxane may be liquid at room temperature (25 ° C.) (for example, the viscosity at 25 ° C. is 100 to 1,000,000 mPa · s, preferably about 200 to 100,000 mPa · s). The average degree of polymerization is preferably from 100 to 800, particularly preferably from 150 to 600.
The (B) organohydrogenpolysiloxane is represented by the following average composition formula (2), and is at least 2, preferably 3 or more (usually 3 to 200), more preferably 3 to 100 in one molecule. Those having hydrogen atoms bonded to silicon atoms are preferably used.

R ² _b H _c SiO _{(4-b-c) / 2} (2)
Here, R ² in the average composition formula (2) is the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms. B is 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0.

The content of hydrogen atoms (Si—H) bonded to the silicon atoms is preferably 0.001 to 0.017 mol / g, particularly 0.002 to 0.015 mol / g in the organohydrogenpolysiloxane.
Examples of the organohydrogenpolysiloxane (B) include trimethylsiloxy group-capped methylhydrogen polysiloxane at both ends, trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer at both ends, and dimethylhydrogensiloxy group-capped dimethyl at both ends. Polysiloxane, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane diphenylsiloxane-dimethylsiloxane _copolymers, copolymers consisting of _(CH 3) 2 _{HSiO 1/2} units and _{SiO 4/2} units, and, (C _{3) 2} HSiO _1/2 units and _{SiO 4/2} units and _{(C 6} H ₅₎ copolymers composed of _{SiO 3/2} units and the like.

The compounding amount of the organohydrogenpolysiloxane (B) is preferably 0.1 to 30 parts by mass, particularly 0.3 to 20 parts by mass with respect to 100 parts by mass of the (A) organopolysiloxane. preferable. The molar ratio of the hydrogen atom bonded to the silicon atom with respect to the alkenyl group of (A) organopolysiloxane is preferably 0.3 to 5.0, particularly preferably 0.5 to 2.5. .
The inorganic filler (C) is a component suitable for obtaining low roller permanent set, volume resistivity being stable over time, and sufficient roller durability. The inorganic filler has an average particle size of 1 to 30 μm, preferably 2 to 20 μm, and a bulk density of 0.1 to 0.5 g / cm ³ , preferably 0.15 to 0.45 g / cm ³ . If the average particle size is less than 1 μm, the electrical resistivity may change over time, and if it is greater than 30 μm, the durability of the elastic layer 3 may be reduced. If the bulk density is less than 0.1 g / cm ³ , the compression set may deteriorate and the electrical resistivity may change over time. If it exceeds 0.5 μm, the elastic layer 3 has insufficient strength and is durable. May decrease. The average particle diameter can be determined as a weight average value (or median diameter), for example, using a particle size distribution measuring device such as a laser diffraction method, and the bulk density is a measurement of the apparent specific gravity according to JIS K 6223. It can be determined based on the method.

Examples of such inorganic fillers include diatomaceous earth, pearlite, mica, calcium carbonate, glass flakes, and hollow fillers, among which diatomaceous earth, pearlite, and foamed pearlite are preferable.
The compounding amount of the inorganic filler is preferably 5 to 100 parts by mass, and particularly preferably 10 to 80 parts by mass with respect to 100 parts by mass of (A) organopolysiloxane.

  Examples of the (E) addition reaction catalyst include platinum black, platinum chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and an olefin, platinum bisacetoacetate, palladium And catalyst based on rhodium and rhodium. The addition amount of the addition reaction catalyst can be a catalytic amount. For example, the amount of platinum group metal is 0.000 relative to the total mass of (A) organopolysiloxane and (B) organohydrogenpolysiloxane. It is preferably 5 to 1,000 ppm, particularly preferably about 1 to 500 ppm.

In addition to the above components, this addition curable liquid silicone rubber composition is a low molecular siloxane ester, a silanol, for example, a dispersant such as diphenylsilanediol, a heat resistance improver such as iron oxide, cerium oxide, iron octylate, Various carbon functional silanes that improve adhesiveness and moldability, halogen compounds that impart flame retardancy, and the like may be included within a range that does not impair the object of the present invention.
The addition-curable liquid silicone rubber composition preferably has a viscosity of 5 to 500 Pa · s at 25 ° C., particularly preferably 10 to 200 Pa · s.

In the preparation process in this invention, the liquid silicone rubber composition, water-soluble particles, and water are mixed to prepare a mixture.
The water-soluble particles may be particles of a water-soluble substance that dissolves in water at, for example, 0 to 100 ° C. Examples of the water-soluble substance include salts and sugars.
The salt is an inorganic compound that is easily finely powdered, does not decompose and gasify at the curing temperature (110 ° C. to 160 ° C.) in the curing process, and can be easily washed with water after heating. Salts such as sodium sulfate and sodium nitrate are used.

As the sugar, any of monosaccharides such as pentose and hexose, disaccharides such as saccharose and maltose, and polysaccharides such as starch and glycogen can be used, and these can be used in combination.
Among these, a sugar whose solubility increases with an increase in temperature is preferable, and sugar is particularly preferable.
The water-soluble particles may be, for example, granules or powders in terms of easy mixing with the silicone rubber composition, and may have any shape such as a spherical shape or a needle shape. The water-soluble particles preferably have a uniform particle size from the viewpoint of forming a uniform cell. For example, the particle size distribution is preferably 500 μm or less. The water-soluble particles preferably have an average particle size of, for example, 80 to 500 μm, and particularly preferably 100 to 400 μm. When the water-soluble substance has a particle size distribution and an average particle size in the above-mentioned range, it is possible to obtain an effect that the formed cell can be stably formed and can be easily melted. The particle size distribution and the average particle size can be directly observed and measured with a microscope or the like, and the distribution can also be grasped from the measured values at 100 locations. The particle size distribution and average particle size of the water-soluble particles can be adjusted by classification using a sieve having a specific mesh, for example.

  The mixing amount of water when preparing the mixture is 0.1 to 5 parts by mass, preferably 0.5 to 3.3 parts per 100 parts by mass of the silicone rubber component contained in the liquid silicone rubber composition. 5 parts by mass. If the water content is less than 0.1 parts by mass, the desired effect may not be obtained. On the other hand, if the amount of water exceeds 5 parts by mass, the water-soluble particles dissolve and the granularity cannot be maintained. If the water content is within the above range, the detailed reason is not clear, but almost all of the water-soluble particles are rapidly eluted to form a porous structure. Usually, water is poorly compatible or miscible with silicone rubber. When water and silicone rubber are used in combination, for example, they are separated, and there are problems such as pinholes and other defects in the molded product. It is common knowledge not to use water in rubber or silicone rubber compositions. However, according to the study of the inventors of the present invention, surprisingly, when the water-soluble particles and water are first kneaded, the liquid silicone rubber composition, the water-soluble mixture and the water kneaded material are kneaded. It was found that water-soluble substances, particularly sugar, can be easily and quickly eluted from the molded body in the elution step described later. The reason for this is contrary to technical common sense and is not known in detail. However, when it is taken into consideration, the water covering the water-soluble particles in the molded body and the liquid silicone rubber composition are repelled and the water-soluble particles and the liquid silicone rubber composition are repelled. The inventor speculates that a thin film of water is formed between the two and the water that has entered the molded body through this thin film tends to come into contact with the water-soluble particles.

  As described above, the water-soluble particles may be mixed with a specific amount of water. However, the water-soluble particles are more excellent in its effect, so that the water-soluble particles can be uniformly coated on the surface of the water-soluble particles. It is preferable that the conductive particles are mixed. Thus, in order to mix water and water-soluble particle | grains so that the surface of water-soluble particle | grains may be coat | covered, methods, such as a spray, are employable, for example.

  In the production method according to the present invention, the liquid silicone rubber composition thus prepared, water-soluble particles and water are mixed. At this time, the water-soluble particles to be mixed are 50 to 200 parts by mass with respect to 100 parts by mass of the silicone rubber component contained in the liquid silicone rubber composition. When the mixing amount of the water-soluble particles is less than 50 parts by mass, the water-soluble particles are dispersed without being close to or in contact with each other, and the water-soluble particles cannot be eluted in the step of dipping described later, and the silicone rubber sponge has open cells. May not be manufactured. On the other hand, when the amount of the water-soluble particles exceeds 200 parts by mass, the skeleton of the silicone sponge becomes brittle when the water-soluble particles are dissolved, and the shape may not be maintained. The water-soluble particles are preferably mixed with the liquid silicone rubber composition in a proportion of 60 to 180 parts by mass in terms of maintaining a sponge structure, and mixed with the liquid silicone rubber composition in a proportion of 80 to 150 parts by mass. It is particularly preferred that The mixing method is not particularly limited, and examples thereof include a method in which water-soluble particles are introduced into a liquid silicone rubber composition at room temperature and normal pressure and uniformly mixed with a stirrer, a kneader, or the like. In this way, the step of preparing the mixture is completed.

In the manufacturing method according to the present invention, a step of molding the prepared mixture is then performed.
In addition, various additives may be contained in the mixture. Examples of the various additives include, for example, auxiliary agents such as the chain extender and the crosslinking agent, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softening agents, Examples thereof include a plasticizer, an emulsifier, a heat resistance improver, a flame retardant improver, an acid acceptor, a heat conductivity improver, a release agent, and a solvent. These various additives may be commonly used additives or may be specially used additives depending on applications.

  The mixture is, for example, from several minutes to several hours, preferably from 5 minutes until it is uniformly mixed using a rubber kneader such as a two-roller, three-roller, roll mill, Banbury mixer, and dough mixer (kneader). It is kneaded and molded at room temperature or under heating for 1 hour.

  The shape for molding the mixture in the molding step is appropriately selected depending on the application and the like, and examples thereof include a plate shape, a block shape, a tubular shape, an annular shape, a prismatic shape, and a cylindrical shape. In the method of manufacturing a silicone foam roller according to the present invention, the silicone foam roller is formed into a tubular shape having a shaft hole slightly smaller than an outer diameter of a shaft body described later.

  In order to produce a tubular silicone rubber sponge, a tubular molded body can be produced, for example, as follows. That is, a mold release agent is applied to the inner peripheral surface of a mold having a cylindrical inside cavity. With the holding hole of the lower end piece and the holding hole of the upper end piece, the shaft body is held so as to pass from one end of the cavity to the other end in the cavity so that the axis of the shaft body is along the axis line of the cavity. Pour the mixture from the sprue of the bottom piece until it begins to flow out of the vent into the reservoir. Subsequently, it heats from the exterior of a metal mold | die to predetermined temperature, hold | maintains at the temperature for predetermined time, and heat-hardens a mixture. After heat curing, the mold is allowed to cool, the tubular molded body is taken out of the mold, and rubber adhering portions in the sprue and vent are cut and removed to obtain a tubular molded body. In addition, you may adhere | attach using what applied the primer process to the shaft beforehand.

Moreover, the block shape creation for open-cell ratio measurement can obtain what was shape | molded by cutting what was shape | molded similarly to the above to arbitrary magnitude | sizes.
In the manufacturing method according to the present invention, a curing step for curing the molded body is then performed.
This curing process is a curing process excluding final curing that is usually performed at a high temperature when the molded body is cured (heated) in a plurality of times. For example, when the molded body is subjected to primary curing and secondary curing, this curing step is a primary curing step. The curing conditions in this curing step are set such that the liquid silicone rubber composition is cured and the water-soluble particles are not melted, melted, decomposed or burned out. For example, when the water-soluble substance is sodium chloride, the heating temperature is set to 70 to 100 ° C., and when the water-soluble substance is sugar, the heating temperature is set to 30 to 100 ° C.

The curing step is preferably performed within 72 hours after the mixture is prepared in the preparation step. When the mixture is cured after exceeding 72 hours, the liquid silicone rubber composition and the water-soluble particles coated with water are separated before the mixture is cured, so that a silicone rubber sponge having a uniform open cell ratio cannot be produced. is there. The elapsed time is particularly preferably within 24 hours in that a desired silicone rubber sponge can be produced.
In the manufacturing method according to the present invention, an elution step is then performed. The elution step may be any method that can elute water-soluble particles from the cured product obtained in the curing step. Examples thereof include a method of immersing the cured product in water, a method of spraying water on the cured product, and the like. The elution step can be performed under a normal temperature and normal pressure environment, or can be performed under reduced pressure under cooling or heating. In the production method according to the present invention, it is preferable to carry out under reduced pressure at which water can forcibly enter the hardened body in that water-soluble particles can be efficiently eluted, and it is taken out from the water after immersion under reduced pressure. Thus, the step of returning to normal pressure can be repeated.

  Further, in the production method according to the present invention, ultrasonic vibration is performed when the cured body is immersed in water, but water can be forced to enter the cured body and water-soluble particles can be efficiently eluted. It is preferable. The ultrasonic vibration method is not particularly limited, and may be, for example, a direct method in which a cured body immersed in water is directly vibrated, an indirect method in which water in which the cured body is immersed is vibrated, or a cured body is immersed. An indirect method of vibrating a container that contains water may be used.

In the production method according to the present invention, almost all water-soluble particles can be eluted from the cured product in this way.
In the manufacturing method according to the present invention, an inspection step for inspecting the residual amount of water-soluble particles in the cured body may be performed before the step of secondary curing performed as desired.

In the production method according to the present invention, a step of further curing the porous molded body thus obtained is carried out as desired. This curing step is, for example, a secondary curing step in which secondary curing is performed. This secondary hardening process is implemented by heating a porous molded object, for example to 120-250 degreeC over 4 to 20 hours.
Since the porous molded body to which this secondary curing step is applied has almost no water-soluble particles remaining, conditions more severe than the conditions under which the water-soluble particles melt, melt, decompose or burn out can be adopted.

Thus, according to the manufacturing method which concerns on this invention, the silicone rubber sponge which has the said specific open cell ratio can be manufactured.
In the method of manufacturing a silicone foam roller according to the present invention, the step of inserting the shaft body into the shaft hole of the tubular silicone rubber sponge manufactured as described above is performed. In the interpolating step, for example, an adhesive or the like is applied to the outer peripheral surface of the shaft body or the shaft hole of the silicone rubber sponge, and after pressing the shaft body into the shaft hole of the silicone rubber sponge, the adhesive is cured. In the method for manufacturing the silicone foam roller according to the present invention, the curing of the adhesive may be performed simultaneously with the secondary curing step in the manufacturing method according to the present invention. As another process of interpolating, for example, there is a method of press-fitting a shaft body having a primer layer formed on the outer peripheral surface thereof into a shaft hole of a silicone rubber sponge. Note that the shaft used only needs to have good conductive properties, and is usually a shaft called a “core” made of iron, aluminum, stainless steel, brass, or the like. Further, the shaft body 2 may be a shaft body that is made conductive by plating an insulating core body such as a thermoplastic resin or a thermosetting resin. Furthermore, the shaft body 2 may be a thermoplastic resin or a thermosetting resin. The shaft body may be formed of a conductive resin in which carbon black or metal powder is blended as a conductivity imparting agent.

  Thus, in the method for producing a silicone foam roller according to the present invention in which a silicone foam roller is produced using a tubular silicone rubber sponge produced in advance, when the porous tubular molded body is immersed in water, its outer surface And since water-soluble particles can be eluted from the inner surface in addition to both end faces, almost all water-soluble particles can be eluted quickly and reliably. Accordingly, the silicone foam roller manufactured by the method for producing a silicone foam roller according to the present invention and having the silicone rubber sponge as the foam elastic layer is substantially free of water-soluble particles in addition to the above characteristics. When fully mounted on an image forming apparatus, it fully exhibits high durability and excellent rebound properties (excellent permanent compression distortion, that is, distortion-resistant characteristics), thereby improving the printing speed and image quality of the image forming apparatus. It can contribute greatly.

  In the production method according to the present invention, if desired, a step of recovering water-soluble particles from the water from which the cured product has been taken out in the elution step can be performed. In this recovery step, water may be removed by volatilization or evaporation, and for example, heating, leaving or blowing means may be employed. The water-soluble particles recovered from the water in this way are pulverized or crushed, the average particle diameter and the like are adjusted, and can be used again in the manufacturing method according to the present invention. The recovered water-soluble particles can be purified before being reused.

(Examples 1-7, Comparative Examples 1-4)
Granulated sugar sugar particles (product name: stick sugar) manufactured by Mitsui Sugar Co., Ltd., which are water-soluble particles, were ground in a mortar to obtain sugar particles having the particle diameter (average particle diameter) shown in Table 1. Next, the obtained sugar granules are thinly dispersed in a tray, and 2.5 parts by mass of water is uniformly sprayed on 100 parts by mass with spraying from above. Then, it collects immediately in a plastic bag, and mixes sugar grains and water evenly by squeezing the plastic bag. Put 102.5 parts by mass of the water-mixed sugar particles and 100 parts by mass of liquid silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-1353A, B) into a planetary mixer and stir and knead for 15 minutes. This gave a mixture. Next, in the mold having the inner diameter φ35, the produced SUM22 shaft made of Φ17 is held in the center of the cavity by the holding hole of the lower end piece and the holding hole of the upper end piece, and then the mold is assembled, The mixture was injected until it began to flow out of the vent into the reservoir. Subsequently, it heated to 120 degreeC from the exterior of the metal mold | die, was hold | maintained for 30 minutes at the same temperature, and the said mixture was heat-molded. After the heat molding, the mold was allowed to cool and the molded product was taken out from the mold, and the sprue and vent portions where the rubber was adhered were cut and removed to produce a tubular molded body.

This tubular molded body is cut to a thickness of 10 mm, and is squeezed with running water at room temperature, and then immersed in an ultrasonic vibrator (product name: US-1 manufactured by SND Corporation) with water. Then, the mixture was subjected to ultrasonic vibration at 38 kHz for 1 hour to elute the sugar contained in the molded body.
When the molded body was pulled up from water and dried, a silicone rubber sponge could be obtained.
Table 1 shows the results of measuring the open cell ratio, average cell diameter, and Asker C hardness of each of the produced silicone foam rollers based on the above method. In Comparative Example 2, the data could not be acquired because the sponge could not be formed.
(Example 8, Comparative Example 5)
An electroless nickel-plated shaft body in which a silicone adhesive (silicone adhesive product name: KE-1880 manufactured by Shin-Etsu Chemical Co., Ltd.) is attached to the center hole formed in the tubular silicone rubber sponge ( Insert 18mm diameter x 350mm length, SUM22) shaft body, heat treatment at 200 ° C for 1 hour in gear oven, then let stand at room temperature for 1 hour or more, then cut the porous molded body at both ends, A roller having a so-called “straight shape” porous molded body with an axial length of 300 mm was prepared by grinding the outer diameter to φ30 with a cylindrical grinder. Table 1 shows the average cell diameter, open cell ratio, Asker C hardness, and durability test results of this roller porous molded body.

In Comparative Example 5, since the sugar could not be completely dissolved, the sponge was broken during the test, and data could not be taken.
(Durability test)
Using each elastic roller manufactured in this way and the durability test apparatus 70 shown in FIG. 1, the durability test of each elastic roller was performed to evaluate the decrease in hardness. Specifically, the durability test apparatus 70 is fixed to the lower surface inside the housing and is provided on both sides of the heating roller 71 provided with an internal heater 72 along the axial direction of the heating roller 71. A test roller mounting portion 74 provided on the upper surface inside the housing so as to be movable up and down so as to face the heat insulating material 73 and the heating roller 71, and a pressing force adjusting means 75 capable of moving the test roller mounting portion 74 up and down. For example, a pressure adjusting micrometer is provided. As the heating roller 71, a metal (stainless steel, SUS304) roller having a diameter of 20 mm was used.

Each manufactured elastic roller is mounted on the bearing of the test roller mounting portion 74, and the mounted elastic roller ("elastic roller 76" in FIG. 6) is operated by operating the pressing force adjusting means 75 as shown in FIG. The elastic roller 76 is fixed so that the foamed elastic layer of the elastic roller 76 is recessed 3 mm inside at the pressure contact portion between the heating roller 71 and the elastic roller 76 (that is, the radius of the elastic roller 76 is The distance d between the central axis of the elastic roller 76 and the central axis of the heating roller 71 was adjusted to be 3 mm shorter than the sum of the radii with the heating roller 71). Next, the internal heater 72 was started and the surface temperature of the heating roller 71 was adjusted to 180 ° C. After that, it was rotated for 450 hours at a rotation speed of 180 rpm by a driving means (not shown) provided in the test roller mounting portion 74. The elastic roller was removed from the durability test apparatus 70 every 50 hours from the start of rotation to 450 hours, and the Asker C hardness was measured as described above. The Asker C hardness is measured at three locations in the axial direction and at four locations in the circumferential direction. Specifically, the three locations in the axial direction are a 30 mm portion and an axial line from both ends of the foamed elastic body toward the center. The central part of the direction is the four places in the circumferential direction, and the four places are equally spaced in the circumferential direction with a central angle of 90 ° in each of the three places in the axial direction.
In addition, as a result of this durability test, the hardness reduction amount is 3 ° or less as OK.

70 Durability Test Device 71 Heating Roller 72 Internal Heater 73 Insulating Material 74 Test Roller Mounting Part 75 Pressing Force Adjusting Means

Claims (5)

With respect to 100 parts by mass of water-soluble particles, so that the water 0.15 parts by 5.0 parts by weight, a step of kneading the above and water-soluble particles, a liquid silicone rubber composition, mixed refining the water-soluble particles and a water, wherein the liquid silicone 50 parts by 200 parts by weight water-soluble particles with respect to 100 parts by mass of the silicone rubber component contained in the rubber composition and water 0.1 parts by 5 mass a preparation step of preparing a mixed to the mixture such that the parts, a shaping step of shaping the said mixture,
A curing step of curing the obtained molded body, an elution step of eluting the water-soluble particles from the obtained cured body,
A method for producing a silicone rubber sponge, comprising: 2. The method for producing a silicone rubber sponge according to claim 1, wherein the silicone rubber sponge has an open cell ratio of 65 % to 98%.   The method for producing a silicone rubber sponge according to claim 1 or 2, further comprising a recovery step of recovering the water-soluble particle-forming substance eluted in the elution step.   The method for producing a silicone rubber sponge according to any one of claims 1 to 3, wherein the forming step is a tubular forming step of forming the mixture into a tubular shape.   A method for producing a silicone foam roller, comprising an insertion step of inserting a shaft body into a through hole in a tubular silicone rubber sponge produced by the production method according to claim 4.

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