JP2008273023A - Method for manufacturing soft foam with surface skin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foam manufacturing method for simply manufacturing a soft foam with a very smooth skin at low costs and a roller manufacturing method for simply manufacturing a developing roller, at low costs, having image quality enhanced in relation to image defects due to the unevenness of the surface of the roller and having a good balance between hardness and elastic recovery. <P>SOLUTION: The manufacturing method comprises at least a process for preparing a foaming material of a liquid resin raw material by mechanical foaming, a process wherein before the foaming material is poured into a mold for molding, the cavity of the mold for molding is vacuumized in advance to such a degree of vacuum that when the foaming material is poured in the mold for molding, it is defoamed, a primary pouring process for filling the foaming material into the cavity of the mold for molding while keeping the degree of vacuum, and a secondary pouring process wherein after a vent hole from the cavity of the mold for molding is closed, the foaming material is poured so that the pressure in the cavity becomes in a range of the atmospheric pressure to the atmospheric pressure +0.03 MPa. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a soft foam having a non-foamed or low magnification skin.

  Conventionally, a soft foam formed by foaming a liquid resin is excellent in flexibility, cushioning properties, lightness, etc., and economically high in that it can reduce the amount of raw material resin used in products. Are widely used in various fields.

  Such foams may form a non-foamed or low-foamed skin on the surface of the foam when the application requires surface smoothness, air tightness, and even a good appearance. Often manufactured.

  For example, the foam as described above is also expected as a member used in office automation equipment including an electrophotographic printing apparatus such as a copying machine, a printer, and a facsimile machine.

  More specifically, the electrophotographic printing apparatus includes a charging roller 11, an exposure unit 12, a developing roller 1, a transfer roller 13, and a cleaning blade 15 with a photosensitive drum 10 at the center as shown in FIG. is there. The developing roller 1 is provided between the vicinity of the opening of the toner container 16 and the photosensitive drum 10. The toner storage unit 16 stores toner in a charged state.

  In the electrophotographic printing apparatus, the photosensitive drum 10 is uniformly charged by the charging roller 11 and exposed by the exposure unit 12 to form an electrostatic latent image on the photosensitive drum 10. Further, the developing roller 1 is pressed against the photosensitive drum 10 to supply toner to the photosensitive drum 10. The toner is supplied to the photosensitive drum 10 in a charged state, and the toner is supplied onto the electrostatic latent image to form a toner image. Then, the toner image is transferred to a recording paper or the like sandwiched between the photosensitive drum 10 and the transfer roller 13.

  Further, the remaining toner is scraped off by the cleaning blade 15, collected in the toner container, and reused.

  As described above, the developing roller 1 has a function of conveying toner to an electrostatic latent image carrier such as the photosensitive drum 10.

  FIG. 2 is a sectional view of a general developing roller 1 and a partially enlarged view thereof.

  As disclosed in Patent Document 1, the developing roller 1 has a conductive shaft (core body) 2 made of stainless steel, SUM, or aluminum alloy, and an elastic layer 3 is provided around the shaft. A surface layer portion 5 is provided on the outer periphery thereof.

  It is important that the developing roller 1 has an appropriate hardness and elasticity. The developing roller 1 is also required to have high dimensional accuracy.

  From these viewpoints, as the material of the elastic layer 3, a soft foamed material obtained by heat-curing a liquid resin material is often used. That is, the hardness of the developing roller 1 can be lowered by using, as the developing roller 1, the foaming roller in which the elastic layer 3 made of the foam is provided on the outer periphery of the conductive shaft (core body) 2.

  As a method for producing the elastic layer 3 of the foaming roller, the core body 2 is placed in a cylindrical mold, a liquid mixture of a liquid resin raw material and a foaming agent is poured into the mold frame, After the liquid resin raw material is foamed in the tee, the mold is heated to react and cure the liquid resin raw material, or the liquid resin raw material foam is formed into a hollow shape, and the core 2 is formed on the foam. A method of filling and then molding the surface of the foam by polishing is generally known.

  Further, as a manufacturing method of the surface layer portion 5 of the foaming roller, the surface layer portion raw material resin is adhered to the outer periphery of the elastic layer 3 manufactured by the above method by a dipping method or a spray method, and the surface layer portion is formed by a chemical reaction or drying. A method of curing the raw material resin to form the surface layer portion 5 and a method of covering the outer periphery of the elastic layer 3 with a sleeve formed of the surface layer portion raw material resin are generally known.

  When the foaming roller is manufactured by the method as described above, if irregularities and pores are present on the outer peripheral surface of the elastic layer 3, traces of these irregularities and pores appear on the outer peripheral surface of the surface layer portion 5, and the developing roller When these are used, these traces are transferred to the image of the recording paper and become a problem. Therefore, when the elastic layer is formed of a foam, it is desirable that the elastic layer surface be smooth.

Patent Document 2 proposes a method for molding an integral skin foam having a low foaming self-skin layer and a highly foamed core using a polyurethane material.
JP 2001-304245 A JP 2001-96544 A

  As a method of forming the skin on the surface of the foam, for example, a method of bonding or fusing a non-foamed skin material to the foam is known, but in the case of a soft foam, the flexibility of the foam is reduced. In order not to be damaged, it is necessary to use a soft skin material, and there is a problem that the unevenness of the foam surface cannot be sufficiently smoothed.

  In addition, a method is also known in which a foam is placed in a cavity of a mold, a skin raw material resin is injected into a space sandwiched between the cavity inner surface and the foam, and the skin raw material is cured to form a skin. However, there is a problem that a process for forming the epidermis is necessary and the operation becomes complicated.

  Japanese Patent Application Laid-Open No. 2001-96544 proposes a method of molding an integral skin foam having a low foaming self-skin layer and a high foaming core using a polyurethane material. This method includes a step of depressurizing the inside of a cavity of a mold and a step of flowing and filling a polyurethane material by injecting and foaming the polyurethane material, and at a portion far from the surface portion of the polyurethane material. A highly foamed core is formed, and a low foam self-skin layer is formed near the surface of the polyurethane material.

  More specifically, the foaming of the polyurethane material proceeds when the gas contained in the polyurethane material or the carbon dioxide gas generated by the reaction of water and the isocyanate component in the polyurethane material expands under reduced pressure. In the part far from the surface part of the material, the generation of carbon dioxide gas and the thickening due to the urethane reaction are promoted by urethane reaction heat, resulting in high foaming, and in the vicinity of the surface part of the polyurethane material, the reaction heat escapes to the mold to increase the viscosity and carbonation. The generation of gas is suppressed, and further, degassing is performed by reducing the pressure, thereby reducing the magnification.

  However, in the above method, since the pressure inside the foam cell is kept lower than atmospheric pressure until the end of curing, sink marks and voids are generated after curing when molding a soft foam by this method. There was a problem that it was easy.

  Therefore, the present invention pays attention to the above-mentioned problems, and in the foam molding method by pouring a liquid resin into a mold, there is no sink or void on the surface, and a soft foam having a smooth surface formed. It is an object to develop a method for producing a foam that can be produced easily and inexpensively.

  Furthermore, according to the present invention, it is possible to easily and inexpensively produce a developing roller that improves the image quality defect due to the unevenness of the roller surface and has a good balance between hardness and elastic resilience by using the production method. Development of a method for manufacturing a roller is an issue.

  In order to solve this problem, the invention described in claim 1 includes a step of injecting a foamable material of a liquid resin raw material into a mold, and foaming and filling the foamable material, and then reaction-curing and foam-molding. A process for producing a soft foam with a skin, wherein at least a step of preparing a foamable material of a liquid resin material by mechanical foaming, and before injecting the foamable material into a mold in advance The process of depressurizing the inside of the mold cavity to a degree of vacuum at which the foamable material is defoamed when injected into the mold, and the foamability while maintaining the degree of vacuum. After the primary injection step of filling the mold cavity with the material and closing the exhaust port from the mold cavity, the pressure in the cavity is in the range of atmospheric pressure to atmospheric pressure + 0.03 MPa or less. The foamable material Characterized in that it comprises a secondary injection step of injecting a process for producing a skin-integrated flexible foam.

  In the method for producing a flexible foam of the present invention, the foamable material is injected into the mold by first injecting and filling the foamable material into a cavity that has been depressurized to a degree of vacuum at which the foamable material is degassed, and further molding. After closing the exhaust port from the cavity of the mold, the pressure in the cavity has the same meaning as the range of atmospheric pressure to atmospheric pressure + 0.03 MPa (the range of atmospheric pressure to atmospheric pressure + 0.03 MPa or less. Inject foamable material to be the same). In the present invention, the first injection process is described as a primary injection process, and the injection process performed after the completion of the primary injection process is described as a secondary injection process.

  In the method for producing a flexible foam of the present invention, defoaming occurs at the surface portion of the foamable material in the primary injection step, and a non-foamed or low-magnification skin layer is formed. This skin layer continues to increase in thickness until defoaming continues until it comes into contact with the cavity inner mold surface. However, after contact with the cavity inner mold surface, defoaming does not occur and the skin layer Maintains the thickness when it comes into contact with the cavity inner mold surface.

  By the above mechanism, the foamable material is filled into the cavity while a non-foamed or low magnification skin layer is formed between the cavity inner mold surface and the foamed layer.

  In the above mechanism, it is desirable that defoaming continuously occurs on the surface of the foamable material not in contact with the cavity inner mold surface until the primary injection step is completed.

  Therefore, in the method for producing a soft foam of the present invention, it is desirable to maintain the pressure in the cavity at a vacuum level at which defoaming occurs on the surface of the foamable material from the start to the end of the primary injection step.

  In the method for producing a flexible foam of the present invention, after the primary injection step is completed, the exhaust port from the mold cavity is closed, and then the secondary injection step is performed to reduce the pressure in the cavity to atmospheric pressure. Adjust to the range of ~ atmospheric pressure +0.03 MPa. After adjusting the pressure in the cavity, the foamable material in the cavity is reaction-cured to prevent the foamed cell's internal pressure from becoming lower than atmospheric pressure, and soft and free from sink marks and voids A foam can be obtained.

  As a means for foaming the liquid resin raw material in the method for producing a flexible foam of the present invention, mechanical foaming (physical foaming) is preferable in that it is easy to control the completion time of foaming during the primary injection step.

  In the chemical foaming in which the liquid resin raw material does not completely foam during the primary injection step, the skin layer of the foamable material is not formed or foaming starts from the formed skin layer, which is not desirable in that a smooth skin cannot be formed.

  The invention according to claim 2 is a step of arranging a metal shaft in a cylindrical mold, and a step of injecting a foamable material of a liquid resin raw material into the mold in which the shaft is arranged, A method of producing a soft foam with a skin comprising a step of foaming and filling the foamable material, followed by reaction curing and foam molding, and further comprising at least a foamable material of a liquid resin material by mechanical foaming. Before mixing and injecting the foamable material into the mold, the degree of vacuum is such that when the foamable material is injected into the mold, the foam is defoamed in advance. Until the pressure is reduced, the primary injection step of filling the foamable material into the cavity of the mold while maintaining the degree of vacuum, and the exhaust port from the cavity of the mold is closed. The pressure in the tee is above atmospheric pressure Characterized in that it comprises a secondary injection step of injecting the foamable material so that the range atmospheric pressure + 0.03 MPa, a method of manufacturing a skin-integrated foam roller.

  In the foaming roller manufacturing method of the present invention, the flow path of the foamable material in the mold cavity is narrow and the foamable material has a high viscosity. Therefore, the foaming roller is formed on the surface of the foamable material in the primary injection step. Most of the non-foamed or low-foamed skin layer is disposed on the inner side surface of the cylinder in the cavity. Therefore, the foaming roller which forms the elastic layer which has a smooth skin in an outer peripheral part can be obtained with the manufacturing method of the foaming roller of this invention. This skin has no pores or irregularities, and the outer peripheral surface of the surface layer is smooth even when the outer layer is formed on the outer periphery of the elastic layer in another process.

  According to the method for producing a soft foam of the present invention, a flexible soft foam having a skin excellent in smoothness and airtightness on the surface can be produced more easily.

  Furthermore, according to the method for producing a foam roller of the present invention, a foam roller having no irregularities or traces of pores derived from the elastic layer on the surface can be produced more easily.

  Embodiments of the present invention will be described below.

  The structure of the mold used in the method for producing a foam of the present invention has a cavity filled with a foamed liquid resin raw material, and when the foamable material made of the liquid resin raw material is injected into the cavity, The inside of the cavity is not particularly limited as long as the pressure can be reduced to a vacuum level at which the foamable material is degassed, and the vacuum level can be maintained. For example, as shown in FIG. A mold 19 can be used.

  The mold 19 is composed of an upper mold 17 and a lower mold 18, and when both molds 17 and 18 are closed, a cavity 20 is formed.

  The lower mold 18 is provided with a foamable material injection gate 33 and an in-cavity exhaust gate 32. The gates 33 and 32 are provided with gate opening and closing valves 23 and 24, respectively.

  The end of the foam control material injection gate 33 has a structure that allows the foamable material injection nozzle 21 to contact the foamable material injection gate 21. The foamable material injected from the injection nozzle 21 passes through the gate 33 and the valve 23 to form a cavity. 20 can be injected. A sealing material 27 is disposed on the contact surface between the injection nozzle 21 and the lower mold 18 to prevent leakage from the contact surface when the inside of the cavity 20 is decompressed.

  Further, the in-cavity exhaust gate 32 is branched halfway, and the movable pin 25 and the movable pin stopper 31 are arranged at one end of the branched branch. A seal material 29 is disposed on the side surface of the movable pin 25, and a seal material 30 is disposed on the head portion.

  The suction head 22 can be brought into contact with the other branch destination end. In the suction head 22, a seal material 28 is disposed on the surface that contacts the lower mold 18, and prevents leakage from the contact surface when the inside of the cavity 20 is decompressed. The suction head 22 is connected to a vacuum pump 34. By bringing the suction head 22 into contact with the lower mold 18, the gas in the cavity 20 is sucked by the vacuum pump 34 via the exhaust gate 32 and the valve 24. The inside of the cavity 20 can be decompressed. In addition, a pressure gauge 26 is disposed on the line connecting the suction head 22 and the vacuum pump 34, and the ultimate vacuum when the inside of the cavity 20 is depressurized can be confirmed.

  The foamable material injection nozzle 21 and the suction head 22 are attached to an air cylinder (not shown) or the like, and have a structure that can be freely attached to and detached from the molding die 19 in accordance with a molding process.

  The material of the mold 19 can be freely selected in consideration of the temperature and pressure at which the mold is used, the durability against the substance in contact with the mold, and the like.

  It is also possible to coat all or part of the mold surface for the purpose of improving the corrosion resistance or improving the peelability of the foam when demolding. .

  The liquid resin raw material used in the method for producing a flexible foam of the present invention is not particularly limited, but the primary injection step and the secondary injection step can be completed in a state where the foamable material is not cured under a room temperature environment. Therefore, it is preferable to use a thermosetting liquid resin.

  As the foaming agent used in the method for producing a flexible foam of the present invention, air, carbon dioxide gas, inert gas, or the like can be used.

  Below, the case where the shaping | molding die 19 is used is made into a specific example, Embodiment of the manufacturing method of the flexible foam of this invention is described based on FIGS.

  The procedure for injecting the foamable material of the liquid resin raw material into the mold 19 shown in FIG. 3 is as follows. First, as shown in FIG. 3, the foamable material injection nozzle 21 and the suction head 22 are brought into contact with the mold 19, the gate valves 23 and 24 are opened, and the inside of the cavity 20 is decompressed by the vacuum pump 34.

  The ultimate degree of vacuum in the cavity 20 is not particularly limited as long as the degree of vacuum is such that defoaming occurs on the surface of the foamable material, but by reducing the pressure to a pressure lower than the vapor pressure of water at the temperature of the foamable material, A slight amount of water contained in the foamable material evaporates to a boiling point, and is more preferable for defoaming.

  After the pressure in the cavity 20 is reduced to a predetermined degree of vacuum, the foamable material is pressurized and injected into the cavity 20 from the foamable material injection nozzle 21 to perform the primary injection process. The foamable material is foamed by a sudden pressure drop at the moment when it is injected from the injection nozzle 21, and then flows in the cavity 20. Defoaming occurs in the surface of the foamable material shown in FIG. 4A under a reduced pressure environment, and a non-foamed or low-magnification skin layer is formed.

  The skin layer formed in A of FIG. 4 is arranged at the boundary surface where the inner surface of the cavity 20 shown in FIG. 4B contacts the foamable material by the flow of the foamable material. The thickness of the skin layer is gradually increased by defoaming at the position A in FIG. 4, but defoaming does not occur at the position B in FIG. 4, so the thickness of the skin layer does not increase.

  By the above mechanism, when the primary injection process is completed, as shown in FIG. 5, the inside of the cavity 20 is foamed with a non-foamed or low-foamed layer at the boundary surface between the cavity inner mold surface and the foamed layer. The material is filled. However, when the primary injection process is completed, the pressure inside the foam cell is lower than the atmospheric pressure. Therefore, even if the foamed material is cured and the foam is molded, irregularities such as sink marks and voids are generated on the surface. It becomes easy to do. In particular, in the case of a soft foam, there are many problems of unevenness.

  Therefore, in the method for producing a flexible foam of the present invention, after the primary injection step is completed, the secondary injection step is performed, and the pressure in the cavity 20 is adjusted from atmospheric pressure to atmospheric pressure + 0.03 MPa, and then heat curing is performed. It is characterized by that.

  In the method for producing a flexible foam of the present invention, it is desirable that the pressure in the cavity 20 when the secondary injection process is completed be in the range of atmospheric pressure to atmospheric pressure + 0.03 MPa. When the pressure in the cavity 20 is lower than the atmospheric pressure, irregularities such as sink marks and voids are likely to occur on the surface of the foam after curing. On the other hand, when the pressure is higher than the atmospheric pressure + 0.03 MPa, the pressure in the foam cell becomes too high, and unevenness such as swelling is likely to occur on the surface of the foam after curing.

  The procedure for secondary injection (performing secondary injection) of the foamable material into the mold 19 is as follows. First, when the primary injection process is completed, the injection from the foamable material injection nozzle 21 is stopped, and the valve 24 is closed to seal the cavity 20 as shown in FIG. Thereafter, the foamable material is injected under pressure from the foamable material injection nozzle 21 until the pressure in the cavity 20 reaches a predetermined pressure.

  The method for confirming the pressure in the cavity 20 at the time of the secondary injection process is not particularly limited. However, in the molding apparatus shown in FIG. 3, when the pressure in the cavity 20 reaches a predetermined pressure, the movable pin 25 moves to determine the pressure. It has a structure that can confirm the arrival of pressure. That is, as shown in FIG. 6, when the pressure in the cavity 20 increases, the movable pin 25 operates so as to be pushed out by the foamable material. Since the operating range of the movable pin 25 is restricted by the stopper 31, the movable pin 25 does not come out of the mold 19. Further, an O-ring 29 is arranged on the movable pin 25 so that the foamable material does not leak from the mold 19 even when the movable pin 25 operates.

  The pressure at which the movable pin 25 starts to operate can be adjusted by the crushing allowance of the O-ring 29. 3 may be arranged between the movable pin 25 and the stopper 31, and the operation start pressure of the movable pin 25 may be adjusted by the pressing force of the spring 35.

  After the secondary injection step is completed, the valve 23 is closed and the foamable material injection nozzle 21 and the suction head 22 are detached from the mold 19 as shown in FIG. Thereafter, the mold is heated to cure the liquid resin raw material, and then the mold is removed to obtain a soft foam with a skin.

  In the method for producing a flexible foam of the present invention, means for heating the mold include steam, an electric heater, a hot air heater, contact with a heating body, induction heating, and the like, but there is no particular limitation.

  By the method for producing a soft foam of the present invention, a soft foam having a skin excellent in smoothness and airtightness can be easily produced.

  Next, the manufacturing method of the foaming roller of this invention is demonstrated.

  The method for producing a foam roller of the present invention is a method for producing a foam roller in which an elastic layer is provided on the outer periphery of the core body and a non-foamed skin layer is provided on the surface of the elastic layer. A resin molded product in which a non-foamed or low-magnification skin layer is provided on the surface of an elastic layer made of a foam is provided on the outer periphery of the core body by the method for producing a foam roller according to the present invention. It is. As a preferred embodiment, an example of producing a developing roller such as a printer will be described.

  The cross-sectional shape of the developing roller (roller) 1 manufactured by the foaming roller manufacturing method of the present embodiment is the same as that shown in FIG. That is, in the roller manufacturing method of the present embodiment, a foamed liquid resin material is filled in a mold on which a conductive shaft (core body) 2 is mounted in advance, and the liquid resin material is transferred from the mold. Heat to cure. The inner diameter of the mold is 16 mm, and the outer diameter of the conductive shaft 2 is 8 mm. Thereby, the developing roller 1 in which the elastic layer 3 having a thickness of about 4 mm is provided on the outer periphery of the conductive shaft 2 and the non-foamed skin layer 5 is provided on the surface of the elastic layer 3 is manufactured.

  The conductive shaft 2 is made of a metal such as stainless steel, a SUM material, or aluminum. The conductive shaft 2 may be made of a material other than metal, for example, a conductive resin.

  The liquid resin raw material used in the method for producing the foaming roller of the present embodiment is not particularly limited as long as it is a general thermosetting resin. For example, at least one alkenyl group capable of hydrosilylation reaction in the molecule. What has an organic polymer which has as a main component can be used. In a more preferred embodiment, the repeating unit constituting the main chain of the organic polymer consists of a saturated hydrocarbon or oxyalkylene unit. Details of the resin raw material in this preferred embodiment are described in, for example, JP-A-8-267612, JP-A-2001-132733, and the like. Specific examples include (A) a polymer having at least one alkenyl group capable of hydrosilylation reaction in the molecule, wherein the repeating unit constituting the main chain is a saturated hydrocarbon or oxyalkylene unit, B) A foamable composition mainly composed of a curing agent having at least two hydrosilyl groups in the molecule and (C) a hydrosilylation catalyst can be used as the foamable material in the present embodiment.

  As a means for foaming the liquid resin raw material in the method for producing a flexible foam of the present invention, mechanical foaming (physical foaming) is preferable in that it is easy to control the completion time of foaming during the primary injection step. As the foaming agent, air, carbon dioxide gas, inert gas, or the like can be used.

  The procedure for preparing the liquid resin raw material is as follows. First, the liquid mixture (liquid resin raw material) of the said (A) component-(C) component, electroconductivity imparting agents, such as carbon black, carbonate, fatty acid, and storage stability improvers, such as dimethyl maleate, is prepared. Next, the liquid resin raw material and a foaming agent (air, carbon dioxide gas, inert gas, etc.) are allowed to coexist in a sealed state and then compressed. Immediately, the compressed liquid resin material is transferred to a mixer and mixed vigorously. At this time, the foaming agent is dispersed in the liquid resin material. Next, the liquid resin resin raw material in which the foaming agent is dispersed is pressurized.

  The adjusted liquid resin material is injected into a molding die on which the conductive shaft 2 is mounted. As a shaping | molding die used here, what is shown, for example in FIG. 8 is mentioned. FIG. 8 is a cross-sectional view of a mold that can be used in the method for manufacturing a foam roller of the present invention. The mold 36 shown in FIG. 8 is a hermetic mold capable of reducing the pressure inside the cavity, and is composed of a mold body 37 and core body holding members 38 and 39, which are connected by clamps 40 and 41. It is.

  The mold main body 37 has a cylindrical shape and is provided with flange portions 42 and 43 at both ends. The inner surfaces of both ends of the mold main body 37 are tapered concave portions 44 and 45. The mold body 37 has an inner diameter of 16 mm and a height of 235 mm.

  One core body holding member 38 seals one end side (the upper end side in the drawing) of the mold main body 37, and includes a convex portion 46 that matches the tapered concave portion 44 of the mold main body 37. Yes. Further, a flange portion 48 that matches the flange portion 42 of the mold body 37 is provided. Further, a shaft insertion hole 50 is provided in the center of the core body holding member 38. A flat portion 52 is formed around the shaft insertion hole 50. Further, the core body holding member 50 is provided with an exhaust port 54, a movable pin 55, a movable pin stopper 56, and an exhaust gate valve 57 for decompressing the inside of the mold cavity.

  The other core body holding member 39 seals the other end side (the lower end side in the drawing) of the mold body 37, and, like the above-described core body holding member 38, the tapered concave portion of the mold body 37. 45, and a flange portion 49 that matches the flange portion 43 of the mold main body 37. The periphery of the shaft insertion hole 51 is a flat portion 53. The core holding member 39 in the lower part of the drawing differs from the core holding member 38 on the upper side in that it has a resin injection port 58, a gate 59, and a gate valve 60 subsequent thereto. That is, the core body holding member 39 includes a resin injection port 58 on the outer end surface.

  In the present embodiment, as shown in FIG. 8, the conductive shaft (core body) 2 is mounted on the mold 36 in advance.

  That is, the core body holding members 38 and 39 are attached to both ends of the mold body 37 with both ends of the conductive shaft 2 inserted into the shaft insertion holes of the upper and lower core body holding members 38 and 39. More specifically, both flange portions are matched and clamped together with clamps 40 and 41.

  In this state, a cavity is formed inside the mold 37, and the conductive shaft 2 is installed at the center thereof.

  The procedure for injecting the foamable material into the mold 36 shown in FIG. 8 is as follows. First, a foamable material injection nozzle (not shown) is pressed against the resin injection port 58, the gate valves 57 and 60 are opened, the air in the cavity is sucked out from the exhaust port 54, and the inside of the cavity is decompressed. The ultimate pressure in the cavity is not particularly limited as long as the degree of vacuum is such that defoaming occurs on the surface of the foamable material, but is preferably a pressure lower than the vapor pressure of water at the temperature of the foamable material.

  As a means for sucking out air in the cavity from the exhaust port 54, a generally known decompression pump or the like can be mentioned, but there is no particular limitation.

  After the pressure in the cavity is reduced to a predetermined pressure, the foamable material is injected under pressure from the foamable material injection nozzle into the cavity to perform the primary injection process. The foamable material is foamed by a sudden pressure drop at the moment of being injected from the injection nozzle, and then flows in the cavity.

  In the cavity, defoaming occurs in the surface portion of the foamable material under a reduced pressure environment, and a non-foamed or low-magnification skin layer is formed. Since the mold 36 has a narrow flow path of the foamable material in the cavity, most of the skin layer is disposed on the cylindrical side surface in the cavity.

  When the primary injection process is completed, the injection from the foamable material injection nozzle is stopped, the exhaust gate valve 57 is closed, and the cavity is sealed. Thereafter, the foamable material is injected under pressure from the foamable material injection nozzle until the pressure in the cavity reaches atmospheric pressure + 0.03 MPa. The mold 36 has a structure in which the movable pin 55 moves to confirm the arrival of a predetermined pressure in the cavity.

  After the secondary injection process is completed, the valve 60 is closed and the foamable material injection nozzle is detached from the mold 36. Thereafter, the mold 36 is heated to cure the liquid resin raw material, and the mold is removed to obtain a roller in which the elastic layer 3 made of a foam is formed on the outer periphery of the conductive shaft 2. A non-foamed or low-foamed skin is formed on the outer peripheral surface of the elastic layer 3.

  By the foam roller manufacturing method of the present embodiment, an elastic layer 3 made of a foam is formed on the outer periphery of the conductive shaft 2, and a non-foamed or low-foamed skin is formed on the outer peripheral surface of the elastic layer 3. A roller having a two-layer structure is produced. Since the outer peripheral surface of the elastic layer 3 is smooth and does not have pores, even when the surface layer portion 5 is formed on the outer periphery of the elastic layer 3 in another step, the outer peripheral surface of the surface layer portion 5 There are no traces of pores.

  The present invention also relates to a method for manufacturing a roller, and more particularly to a method for manufacturing a roller in which a non-foamed or low-magnification skin is provided on the surface of an elastic layer made of a foam.

  In the following, non-limiting examples of the present invention will be described. However, the following Example is one of the preferable examples of this invention.

1. Production of Roller (A) Allyl-terminated polyoxypropylene (trade name: Kaneka Silyl ACS003, Kaneka Corporation): 100 parts by weight
(B) Polyorganohydrogensiloxane (trade name: CR100, Kaneka Corporation): 3.1 parts by weight;
(C) bis (1,3-divinyl-1,1,3,3-tetramethyldisiloxane) platinum complex catalyst (platinum content 3 wt%, xylene solution): 0.06 parts by weight;
Carbon black (trade name: 3030B, Mitsubishi Chemical): 14 parts by weight as a conductivity-imparting agent,
0.04 parts by weight of dimethyl maleate as a storage stability improver,
As other ingredients, calcium carbonate (trade name: MC Coat S-20, Maruo Calcium Co., Ltd.): 25 parts by weight,
The liquid resin raw material obtained by vacuum degassing for 120 minutes at 10 mmHg or less was mixed with air equivalent to 100% thereof and stirred well. Thus, a foamed liquid resin material (foamable material) enclosing fine bubbles was prepared.

  A conductive shaft (core body) 2 (outer diameter 8 mm, length 267 mm) made of SUM is mounted on a molding die 36 (inner diameter 8 mm, height 235 mm) having the structure shown in FIG. The nozzle of the injection machine is brought into close contact with the resin injection port 58 of the molding die 36, and the air in the cavity is exhausted from the exhaust port 54 by a vacuum pump to reduce the pressure in the cavity to 10 mmHg or less. did.

  While maintaining the pressure in the cavity at 10 mmHg or less, the foaming material is injected upward from the resin injection port 58 of the molding die 36 by an injection machine, and after filling the foamable material into the cavity, foaming is performed. The injection of the functional material was stopped, the exhaust gate valve 57 of the mold 36 was closed, and then the foamable material was injected until the movable pin 55 was pushed out of the mold 36.

  After completion of the injection, the valve 60 was closed and the mold 36 was placed in a heating furnace provided with a fan and heated at 140 ° C. for 20 minutes. After the heating, the mold 36 was taken out from the heating furnace and released from the mold 36 to obtain a molded product (foaming roller).

  On the other hand, the nozzle of the injection machine is brought into close contact with the resin injection port 58 of the mold 36, the foamable material is injected upward from the resin injection port 58 with the exhaust gate valve 57 opened, and the foamable material is injected into the cavity. A foaming roller was produced in the same process except that the injection of the foamable material was completed when the filling was completed, and was used as a comparative example.

2. Evaluation of Foaming Roller A cross section of the roller of the example was observed with a microscope. As a result, a non-foamed skin having a thickness of 0.5 mm was formed on the outer periphery of the elastic layer 3 formed of a foam. The outer peripheral surface of the roller of the example was smooth without any pores. On the other hand, when the roller of the comparative example was observed in the same manner, no skin was formed, and there were many pores on the outer peripheral surface.

From the above, it was found that in the roller of the example, a non-foamed skin layer having a thickness of 0.5 mm was formed on the outer periphery of the elastic layer 3, and the outer peripheral surface was smoother than that of the roller of the comparative example.

It is the schematic showing the structure of the printing apparatus by an electrophotographic system. It is sectional drawing of a developing roller. It is sectional drawing of the shaping | molding die used with the manufacturing method of the flexible foam of this invention. It is explanatory drawing which shows the state which is performing the primary injection | pouring process to a shaping | molding die. It is explanatory drawing which shows the state which the primary injection | pouring process of the shaping | molding die was completed. It is explanatory drawing which shows the state which is performing the secondary injection | pouring process to a shaping | molding die. It is explanatory drawing which shows the state which the secondary injection | pouring process of the shaping | molding die was completed. It is sectional drawing of the shaping | molding die used with the roller manufacturing method of this invention. It is an electron micrograph of the roller cross section of an Example. It is an electron micrograph of the roller cross section of a comparative example.

Explanation of symbols

1 Development roller (roller)
2 Conductive shaft (core)
3 Elastic layer 5 Surface layer part 19 Mold 36 Roller mold

Claims (2)

Injecting a foamable material of a liquid resin raw material into a mold,
A process for producing a soft foam with a skin, comprising the step of foaming and filling the foamable material and then subjecting the foamed material to reaction curing and foam molding,
Furthermore, at least a step of preparing a foamable material of a liquid resin raw material by mechanical foaming,
Before injecting the foamable material into the mold, the pressure in the cavity of the mold is reduced to a degree of vacuum that is defoamed when the foamable material is injected into the mold. When,
A primary injection step of filling the foamable material into a cavity of the mold while maintaining the degree of vacuum;
A secondary injection step of injecting the foamable material so that the pressure in the cavity is in the range of atmospheric pressure to atmospheric pressure + 0.03 MPa after closing the exhaust port from the cavity of the mold. A method for producing a soft foam with a skin, comprising: Placing a metal shaft in a cylindrical mold;
Injecting a foamable material of a liquid resin material into the mold on which the shaft is disposed;
A process for producing a soft foam with a skin, comprising the step of foaming and filling the foamable material and then subjecting the foamed material to reaction curing and foam molding,
And at least
A step of preparing a foamable material of a liquid resin material by mechanical foaming;
Before injecting the foamable material into the mold, the pressure in the cavity of the mold is reduced to a degree of vacuum that is defoamed when the foamable material is injected into the mold. When,
A primary injection step of filling the foamable material into a cavity of the mold while maintaining the degree of vacuum;
A secondary injection step of injecting the foamable material so that the pressure in the cavity is in the range of atmospheric pressure to atmospheric pressure + 0.03 MPa after closing the exhaust port from the cavity of the mold. A method for producing a foam roller with a skin, comprising: