JP5056462B2 - Foam rubber production equipment - Google Patents

Description

The present invention relates to a manufacturing ZoSo location of foam rubber, in particular, it relates to forming apparatus manufactured you produce foamed rubber with a mold, such as mold.

  As a method for molding foamed rubber, there are generally methods such as mold molding and extrusion molding. In particular, rubber rollers (pickup rollers, feed rollers, retard rollers, etc.) used in paper feed sections of OA equipment such as laser printers, copying machines, and various terminals have a foam rubber layer made of foam rubber. A foam rubber roller is used. In the method of manufacturing this foam rubber roller (sponge rubber roller), although it differs depending on the material molding method as mold molding, for example, compression molding in which a certain shape is prepared in advance and pre-molded and then pressurized and fluidized, inside the pod There are transfer molding in which a rubber fabric is injected and pressed to form a product shape, and injection molding in which a rubber material is injected into a mold by a screw or the like and foamed.

  Extrusion molding is a method in which a molded product having a constant cross-sectional shape is continuously extruded using an extruder. In the production of foamed rubber, both the mold molding and the extrusion molding are carried out.

  On the other hand, as a rubber roller used for the paper feeding unit, an inner layer (foam rubber layer) made of foam rubber and an outer layer rubber are bonded to improve durability and stabilize the friction coefficient 2 than a rubber roller made only of foam rubber. There is a layered rubber roller.

  In the method of manufacturing the rubber roller having the two-layer structure, a method in which a rubber layer made of an outer layer rubber is adhered to a foamed rubber layer made of the foamed rubber produced by the above method, and a liquid rubber material is used as the foam material. There is a method of spray coating or impregnation, or a method of injecting a liquid rubber material (such as urethane) into the outer layer rubber previously produced and foaming it by the above molding method.

  For example, as shown in FIG. 8A to FIG. 8E, a high heat-resistant resin film 82 is formed on the inner surface of the cylindrical mold 81, and then the roller base 83 is placed in the cylindrical mold 81. Is inserted, and a liquid foamable rubber material 84 is injected between the roller base 83 and the coating 82, followed by vulcanization and foaming to bond the coating 82 and the foamed rubber layer to a two-layer rubber roller. 85 is manufactured.

JP 2000-108223 A JP 2007-85451 A

  However, in the above bonding method, when an adhesive having an appropriate adhesive force is not selected for the adherend such as the foam rubber layer (sponge layer) and the outer rubber layer, the use environment and the use conditions If an adhesive capable of maintaining an appropriate adhesive force is not selected for (load applied during use), the sponge layer and the outer rubber layer are peeled off. In addition, there are problems such as an increase in manufacturing cost due to the bonding process.

  Further, in the above bonding method, the rubber material for the outer layer and the rubber material for the sponge layer are limited to liquid materials. Even when a solid material is used, it is necessary to use a liquefied material once.

  A general rubber material is mainly a solid material, and when it is a liquid material, the material is limited to urethane, silicone, or latex (a solution in which fine particles of rubber are dispersed in water). Urethane and silicone materials have a low coefficient of friction with the paper (friction coefficient = F / W (friction force F, load W)), which is applied to the contact area between the rubber roller for paper feeding and the medium (paper, etc.). Limited. In latex systems, NR (natural rubber), SBR (styrene butadiene rubber), BR (butadiene rubber), NBR (nitrile rubber), CR (chloroprene rubber), etc. are generally used. Due to low storage stability such as precipitation of rubber particles, it is difficult to handle and workability is deteriorated.

  In order to liquefy a solid material, it is necessary to dissolve it in an organic solvent and the like, which requires operations such as a dissolution process and concentration control. Therefore, there is a concern about cost increase or environmental impact.

  When the outer rubber layer is prepared first and the solid rubber is compression-molded to form the foamed rubber layer, the material must be preformed and degassed during vulcanization.

  Further, in the rubber roller for paper feeding, by forming the inside of the outer rubber layer as a foamed rubber layer, it is deformed with a lower load than a solid layer (one solid roller) that is not foamed rubber, so that the nip width ( When a medium is brought into contact with the rubber roller for paper feed with a constant load, the length of the rubber roller for paper feed deformed and brought into contact with the medium can be ensured. It is low and the dimensional accuracy of the foam rubber layer is inferior, so it is difficult to ensure a stable nip width.

  The rubber roller for paper feeding used in scanners and copiers is a stable nip with a lower load to cope with high speed and high durability of the equipment and to feed and separate paper media with different thickness and surface. It is required to maintain the width and coefficient of friction.

An object of the present invention is to provide a laser printer, a copying machine, manufactured ZoSo location of foam rubber which can be suitably used for the OA devices including various terminals.

  Another object of the present invention is to provide a method for producing a rubber roller having a foamed rubber layer made of foamed rubber and having a stable nip width and a friction coefficient at low cost, and a rubber roller obtained by the production method. There is to do.

The foamed rubber production apparatus of the present invention is a foamed rubber production apparatus in which a foamed rubber layer is formed by being in close contact with a pre-molded rubber layer. A solid unfoamed rubber material is placed and heated and pressurized. A preliminary chamber for making a liquid, communicated with the preliminary chamber, the rubber layer is set and a liquid non-foamed rubber material is injected therein, and the injected non-foamed rubber material is vulcanized, A foaming chamber for forming the foamed rubber layer by foaming and a molding chamber for adhering to the rubber layer ; a pod in which the preliminary chamber is formed; and a solid unfoamed rubber material stacked on the pod A cylinder that pressurizes the cylinder, a cylindrical middle mold in which the pod is overlaid and the molding chamber is formed, and a cylindrical upper mold and a cylindrical bottom that are respectively stacked above and below the middle mold A mold, and the upper mold and the mold Each of the molds is an escape hole that passes through the upper and lower sides to release excess unfoamed rubber, and each of the escape holes in which the number of holes, the hole diameter, and the hole shape are set according to the foaming degree of the foamed rubber layer, The total hole area S1 of all upper relief holes formed in the upper mold, or the total hole area S1 of all lower relief holes formed in the lower mold, and the cross section of the foam rubber layer (sponge area ratio of the area S2 of a cross section) (S1 / S2) is 10% to 80% der shall.

  Furthermore, an escape groove for allowing excess unfoamed rubber to escape to the outside of the mold may be formed in the upper mold and the lower mold, respectively.

  According to the present invention, foamed rubber suitable for OA equipment such as laser printers, copying machines, and various terminals can be manufactured. In particular, according to the present invention, an adhesive is used because a certain pressure is applied during foam vulcanization, and the rubber layer and the foam rubber layer are bonded before the skin layer (thin layer without adhesive force after vulcanization) is formed. It is possible to obtain an appropriate adhesive force without the need, and it is possible to easily produce a two-layer rubber having a foam rubber layer made of foam rubber and having a stable nip width and a friction coefficient. It can be applied as a rubber roller for paper feed made of

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, a foam rubber production apparatus used in a foam rubber production method according to a preferred embodiment of the present invention will be described with reference to FIGS. 1 (a), 1 (b), and 2. FIG. In the present embodiment, an example of producing a rubber having a two-layer structure in which a rubber layer (outer rubber layer) is provided outside a cylindrical foam rubber layer (inner rubber, sponge rubber, or inner sponge) made of foam rubber will be described. To do.

  FIG. 1 (a) is an external view of a foamed rubber manufacturing apparatus used in the foamed rubber manufacturing method according to a preferred embodiment of the present invention, FIG. 1 (b) is a partial sectional view thereof, and FIG. It is a decomposition | disassembly partial sectional view of the manufacturing apparatus of the foamed rubber shown in FIG.

  As shown in FIG. 1 (a), FIG. 1 (b), and FIG. 2, a foamed rubber manufacturing apparatus 1 (hereinafter referred to as manufacturing apparatus 1) according to this embodiment forms a foamed rubber layer and is molded in advance. This is an apparatus for producing a two-layer rubber by bonding to a rubber layer.

  The production apparatus 1 includes an injection part 2 for injecting a solid unfoamed rubber material into a liquid and injecting it into a mold, and a mold (mold mold) 7 as a mold that is detachably provided in the injection part 2. Become.

  In this embodiment, these injection | pouring part 2 and the metal mold | die 7 were formed with the metal with high heat resistance and rigidity. Metals used for the injection part 2 and the mold 7 are carbon steel for machine structure, aluminum alloy, general structural rolled steel, carbon tool steel, alloy tool steel, high speed steel, nickel molybdenum steel, chromium molybdenum steel, stainless steel. , There is geralumin steel. Besides these, a copper alloy can be used. These metal surfaces may be plated in order to improve corrosion resistance.

  The injection part 2 includes a preliminary chamber (preliminary molding chamber) 3 for placing (accommodating) a solid unfoamed rubber material as a material for the foamed rubber layer, heating and pressurizing it into a liquid state. The injection part 2 is composed of a pod 4 in which a preliminary chamber 3 is formed, and a cylinder 5 which is stacked on the pod 4 and pressurizes a solid unfoamed rubber material.

  As the main rubber component of the solid unfoamed rubber material, all rubber materials (NR, SBR, BR, NBR, IIR (butyl rubber), Q (silicone rubber), CR, CSM (chlorosulfonated polyethylene) as well as EPDM ), ACM (acrylic rubber), ECO (epichlorohydrin rubber), U (urethane rubber), T (polysulfide rubber), CM (chlorinated polyethylene)) can be used. The solid unfoamed rubber material according to the present embodiment is a compound obtained by kneading a foaming agent, a foaming aid or the like with any of these rubber main components.

  The pod 4 has a pod-side rubber flow path 4f through which a liquid unfoamed rubber material flows at the center of the lower part, and a pod side wall 4w formed so as to cover the periphery above the pod-side rubber flow path 4f. Formed. The preliminary chamber 3 is partitioned and formed above the pod-side rubber flow path 4f and the pod side wall 4w. A convex portion 6 projecting downward is formed at the lower portion of the pod 4, and the pod 4 is detachably provided on an upper mold 7 u described later.

  The cylinder 5 has a front end portion (lower side in FIG. 1B, FIG. 2) 5d fitted to the spare chamber 3, and a rear end portion (flange portion) 5u having a larger diameter than the front end portion 5d is located on the pod side wall 4w. It is formed in a substantially cylindrical shape so as to be overlapped, and is detachably provided on the pod 4.

  The mold 7 includes a molding chamber 8. The molding chamber 8 communicates with the preliminary chamber 3, and a rubber layer is set and a liquid non-foamed rubber material is injected into the molding chamber 8. The injected non-foamed rubber material is vulcanized and foamed to form a foamed rubber layer. Is to be bonded to the rubber layer.

  The mold 7 includes a cylindrical middle mold 7m in which a molding chamber 8 is formed by overlapping the pod 4 through an upper mold 7u, and a cylindrical upper mold overlaid on the middle mold 7m. It consists of a mold 7u and a lower mold 7d that is stacked under the middle mold 7m.

  In the upper mold 7u, a mold side rubber flow path 7f communicating with the pod side rubber flow path 4f is formed at the center, and an upper mold side wall 9 is formed so as to cover the periphery of the mold side rubber flow path 7f. The upper mold side wall 9 is open at the top, and a relief groove 10u that passes through the upper mold side wall 9 in the radial direction and releases excess unfoamed rubber material to the outside of the mold 7 has a predetermined interval. A plurality are formed. The mold side rubber flow path 7f and the upper mold side wall 9 are used to guide surplus unfoamed rubber material from the mold side rubber flow path 7f to the groove 10u and to detachably attach the upper mold 7u to the pod 4. The recess 11 is partitioned. A female-type fitting portion 12f is formed in the lower part of the upper mold 7u so as to be fitted to the upper part of the middle mold 7m and to be detachably provided on the middle mold 7m.

  Around the mold-side rubber flow path 7f of the upper mold 7u, there is an upper relief hole 13u that penetrates the upper mold 7u vertically and allows the unfoamed rubber material to escape from the molding chamber 8 to the recess 11 with a predetermined interval. A plurality of them are formed. The number of holes, the hole diameter, and the hole shape of the upper escape hole 13u are set according to the foaming degree of the foamed rubber layer.

  The middle mold 7m has a molding chamber 8 formed in a substantially columnar shape at the center, and a male mold formed around the upper portion thereof, and is detachably provided on the middle mold 7m by fitting with the fitting portion 12f. And a male fitting portion 14md which is formed around the lower portion of the molding chamber 8 and is detachably provided on the lower die 7d by being fitted to the upper portion of the lower die 7d. .

  The lower mold 7d is formed with a lower mold upper side wall 15 as a female mold fitting part that is fitted to the fitting part 14md at the upper peripheral edge of the lower mold 7d so as to be detachable. A lower mold lower side wall 16 is formed on the lower peripheral edge of the mold 7d.

  The lower mold lower wall 16 is open at the bottom, and a relief groove 10d that passes through the lower mold lower wall 16 in the radial direction and releases excess unfoamed rubber material to the outside of the mold 7 has a predetermined interval. A plurality of them are formed. The relief grooves 10d are formed radially (in four directions, right and left and up and down in FIG. 6B), from the center of the back surface of the lower mold 7d to the lower mold lower side wall 16. The above-described relief groove 10u is also formed radially from the center of the surface of the upper mold 7u to the upper mold side wall 9 (in four directions, left, right, up and down in FIG. 6A described later).

  The depth of these relief grooves 10u, 10d is 1 mm or more, preferably 10 mm or more and less than 20 mm, so that excessive unfoamed rubber material flows without collecting in the mold 7 and can escape to the outside of the mold 7. Good.

  On the central part of the lower mold 7d, a mold pin 17 formed in a substantially cylindrical shape having the same height as that of the molding chamber 8 is provided upright. The outer diameter of the mold pin 17 is larger than that of the pod side rubber flow path 4f and the mold side rubber flow path 7f, and smaller than that of the molding chamber 8. The inner diameter of the mold pin 17 is the same as the outer diameter of the core material inserted through the foamed rubber layer. Moreover, the outer peripheral surface of the mold pin 17 is located inside the upper escape hole 13u.

  Further, a plurality of supply holes 18 are formed in the mold pin 17 for supplying the unfoamed rubber material that has flowed into the mold pin 17 through the pod side rubber flow path 4f and the mold side rubber flow path 7f into the molding chamber 8. Is done.

  The mold pin 17 may be formed integrally with the lower mold 7d or may be formed separately. The material of the mold pin 17 is the same as that of the lower mold 7d.

  At a position around the mold pin 17 of the lower mold 7d, there is a lower release hole 13d that penetrates the lower mold 7d up and down and allows the unfoamed rubber material to escape from the molding chamber 8 to the outside of the mold 7. A plurality of holes are formed on the axis of the upper escape hole 13u with an interval of. The number of holes, the hole diameter, and the hole shape of the lower escape hole 13d are also set according to the foaming degree of the foamed rubber layer.

  Here, a more detailed example in which the rubber having the two-layer structure described above is used as a rubber roller having a foam rubber layer used in a paper feeding unit of an OA device such as a laser printer, a copying machine, and various terminals. Will be explained.

  The material of the rubber layer formed outside the foamed rubber layer is the same as that of the foamed rubber layer except for the foaming agent and the foaming aid. The thickness of the rubber layer (outer layer roller) is 0.3 to 3.5 mm, preferably 0.3 to 3.0, and more preferably 0.5 to 2.5 mm. If the thickness of the rubber layer is less than 0.3 mm, the durability is lowered. When the thickness of the rubber layer exceeds 3.5 mm, the nip width and the friction coefficient become unstable.

  The total outer diameter of the rubber layer and the foamed rubber layer is 20 to 80 mm, preferably 20 to 36 mm. This is because there is almost no need for a total outer diameter of less than 20 mm or a diameter exceeding 80 mm.

  The shape of the upper escape hole 13u and the lower escape hole 13d may be a substantially circular shape, a perfect circle, an ellipse, a long hole, or the like. The upper relief hole 13u and the lower relief hole 13d are the total hole area S1 of all the upper relief holes 13u, or the total hole area S1 of all the lower relief holes 13d, and the transverse section (sponge section) of the foam rubber layer. The area ratio (S1 / S2) with the area S2 may be 10 to 80%, preferably 10 to 70%. If the area ratio is less than 10%, the unfoamed rubber material is difficult to escape, and the pressure in the molding chamber 8 becomes too high to foam. If the area ratio exceeds 80%, the pressure required for foaming cannot be maintained.

  In the present embodiment, considering the total outer diameter of the rubber layer and the foamed rubber layer and the thickness of the foamed rubber layer, the upper escape hole 13u and the lower escape hole 13d are formed into a perfect circle having an outer diameter of 1.0 to 4.0 mm. And 4 to 24 (the number of holes is four or more, which is 16 in the present embodiment).

  Next, a method for producing foamed rubber using the production apparatus 1 will be described.

  First, as shown in FIGS. 2 and 3, the middle mold 7m, the upper mold 7u, and the pod 4 are sequentially stacked on the lower mold 7d in which the mold pin 17 is arranged at the center, and adjacent to the upper mold 7u. Thus, a spare chamber 3 is provided.

  A rubber layer 31 molded in a substantially cylindrical shape in advance is set in the molding chamber 8 in the middle mold 7m, and in this state, a solid unfoamed rubber material sr is placed in the spare chamber 3 of the pod 4, Place cylinder 5 on top of each other.

  In this state, as shown in FIG. 4, the mold 7, the pod 4, and the cylinder 5 are heated to a temperature not lower than the melting point of the unfoamed rubber material sr (for example, 160 ° C. or higher in the case of EPDM). The tip 5d of the cylinder 5 is pushed into the cylinder.

  As a result, the unfoamed rubber material sr is heated in the preliminary chamber 3 and pressurized to form a liquid unfoamed rubber material r, which is poured into the mold pin 17 through the pod side rubber flow path 4f and the mold side rubber flow path 7f. (Arrows pointing downward in FIG. 4) are injected into the rubber layer 31 inside the molding chamber 8 from the supply holes 18 (leftward and rightward arrows in FIG. 4).

  As shown in FIG. 5, the upper relief hole 13u also serves to control the pressure in the molding chamber 8 before the front end portion 5d of the cylinder 5 is further pushed into the preliminary chamber 3 and the unfoamed rubber material r is vulcanized. The excess (excess) unfoamed rubber material r is released from the molding chamber 8 through the lower escape holes 13d (upward and downward arrows in FIG. 5). The unfoamed rubber material r that has escaped from the molding chamber 8 is further escaped to the outside of the mold 7 through the escape grooves 10u and 10d and discharged as shown in FIGS. 6 (a) and 6 (b).

  At the same time, the non-foamed rubber material r injected and filled into the molding chamber 8 is vulcanized and foamed to form a substantially cylindrical foamed rubber layer 32, and the molded substantially cylindrical foamed rubber layer. 32 is bonded to the rubber layer 31.

  Thereafter, the cylinder 5 and the pod 4 are removed from the mold 7, the upper mold 7u and the lower mold 7d are removed from the middle mold 7m, and the two-layer rubber 51 is taken out from the middle mold 7m. A product as a paper feed roller is obtained.

  The operation of this embodiment will be described.

  In the method for producing foamed rubber according to the present embodiment, a pre-molded rubber layer 31 is set in the mold 7, and the solid unfoamed rubber material sr is heated and pressurized in this state in the mold 7. The foamed rubber layer 32 is formed by vulcanizing and foaming the injected unfoamed rubber material r, and the rubber layer 31 is adhered to the rubber layer 31 to obtain a rubber 51 having a two-layer structure.

  More specifically, a rubber layer 31 that is an outer layer roller prepared in advance is fixed to the middle mold 7 m, and an unfoamed rubber material sr is injected from the inside of the rubber layer 31. Excess unfoamed rubber material sr is discharged from the pressure control holes (upper escape hole 13u and lower escape hole 13d), and the molding chamber can be used without fine weight control of solid unfoamed rubber material sr. The optimal amount of unfoamed rubber material r can be injected into 8 with high accuracy.

  Thereby, according to the manufacturing method concerning this embodiment, fixed pressure is applied to unfoamed rubber material r in metallic mold 7 at the time of foaming vulcanization, and skin layer (thin layer without adhesive power after vulcanization) formation Since the foamed rubber layer 32 comes into contact with the rubber layer 31 before, adhesion is possible without using an adhesive, and the rubber 51 having a two-layer structure can be easily manufactured. In addition, the rubber 51 having a two-layer structure obtained by the manufacturing method according to the present embodiment has a stable nip width, and thus the coefficient of friction is a stable value.

  On the other hand, when the outer rubber layer is first prepared as in the past, and the rubber material is preformed and set in the mold, the adhesive strength with the rubber layer is due to the skin layer formation over time until foaming. Get smaller. Also, the pressure in the mold may be too high and the material may not foam.

  In addition, the manufacturing method according to the present embodiment can be applied to a multi-cavity mold (in the case where a single mold has a plurality of products), and the weight of the unfoamed rubber material sr injected individually is measured. Therefore, the pod 4 and the cylinder 5 can be made common and the unfoamed rubber material sr can be injected, and the rubber 51 having a two-layer structure can be obtained at a low cost.

  Further, the unfoamed rubber material sr is injected into the molding chamber 8 with a certain amount of accuracy, and the unfoamed rubber material sr flows from the hole portion for controlling the pressure at the time of vulcanization and foaming. Obtained uniformly. By uniforming the foaming, the amount (size) of crushing of the foamed rubber layer 32 becomes constant, and a stable nip width and friction coefficient can be obtained.

  It is known that the friction coefficient depends on the load, and when the nip width changes, the apparent load (pressure against the contact area) changes, so the friction coefficient is not stabilized.

  The appropriate value of the nip width depends on the dimensions (outer diameter, width, etc.) of the roller, and therefore it is very difficult to describe the optimum range. Therefore, in general, a roller (in this embodiment, a rubber 51 having a two-layer structure) is used. It is replaced by the load when it is bent.

  As an example, when the inventors prototyped a rubber 51 having a two-layer structure having an outer diameter of 27 mm, a width of 10 mm, a thickness of the rubber layer 31 of 1.5 mm, and a foamed rubber layer (sponge) 32 of 3.5 mm, When a load of 3N is applied to this, the nip width is 5 to 6 mm, and the load when the rubber 51 having the two-layer structure is bent by 1 mm is 1.7 to 2.0 N (the friction coefficient is about 1 which is equivalent). 7 to 2.0), and both the nip width and the friction coefficient were very stable.

  The optimum range of the friction coefficient is about 1.0 to 4.0. Note that the friction coefficient of the rubber 51 having the two-layer structure applicable to the rubber roller for paper feeding having the two-layer structure manufactured so far is 1.6 to 4.0, and varies depending on the hardness and material of the sponge. Note that it is difficult for the solid roller (one-layer solid roller) to have a friction coefficient exceeding 3. In general, if there is a friction coefficient of 0.8 or more (more than the friction coefficient between paper and paper), it is possible to separate the paper.

  Further, in the manufacturing method according to the present embodiment, the preliminary chamber 3 of the injection part 2 and the molding chamber 8 of the mold 7 are separated in the apparatus 1, so that the liquefaction process of the solid unfoamed rubber material st The rubber 51 having a two-layer structure can be manufactured continuously from the material input to the product completion while independently performing the molding and foaming processes of the unfoamed rubber r.

  Furthermore, in the manufacturing method according to the present embodiment, before the unfoamed rubber material r is vulcanized, the excess unfoamed rubber material is allowed to escape from the molding chamber 8 through the upper escape hole 13u and the lower escape hole 13d. Since the pressure in the chamber 8 can be controlled, a continuous operation is possible without the need for removing gas during the foaming.

  By using the upper escape hole 13u and the lower escape hole 13d, even when the amount of unfoamed rubber material sr is excessive when the number of products of the mold is plural, excessive unfoamed rubber material Since r flows to the outside of the mold, the foaming is made uniform and the variation in the expansion ratio is small. In the prior art, it is necessary to precisely control the input weight for each cavity.

  The amount of crushing (dimension) of the foamed rubber layer 32 becomes constant due to uniform foaming, and this point also acts to obtain a stable nip width and friction coefficient in the rubber 51 having a two-layer structure.

  According to the foamed rubber manufacturing apparatus 1 according to the present embodiment, the foamed rubber manufacturing method according to the present embodiment can be easily implemented.

  Further, in the apparatus 1, since the middle mold 7m, the upper mold 7u, the lower mold 7d, the pod 4 and the cylinder 5 constituting the mold 7 are all detachably provided, the apparatus 1 The operation of No. 1 is simple and the workability is good. In particular, the types of the middle mold 7m, the upper mold 7u, and the lower mold 7d can be easily changed, and the parts can be easily replaced.

  Further, in the device 1, the number of holes, the hole diameter, and the hole shape are set according to the foaming degree of the foamed rubber layer 32 that the upper escape hole 13u and the lower escape hole 13d are to be manufactured. If the different upper and lower molds are changed, the foamed rubber layer 32 having a desired degree of foaming can be obtained.

  For example, as the upper die, in addition to the upper die 7u having the number of holes: 16 in FIG. 7A described above and a hole diameter: 1.0 to 4.0 mm and having an upper circular escape hole 13u, FIG. (B) The number of holes: 8 as in the upper mold 71b, a perfect circle having a larger diameter than the upper mold 7u, and the number of holes: 24, as in the upper mold 71c of FIG. Each upper mold such as a perfect circle having a smaller diameter than the mold 7u, the number of holes: 4 like the upper mold 71d in FIG. 7D, and a long hole having substantially the same width as the hole diameter of the upper mold 7u, It can be used according to the foaming degree of the foamed rubber layer to be produced. Among these, when the upper mold 71d is used, a foamed rubber layer having the largest foaming degree can be obtained.

(Examples 1-14)
Using the apparatus 1, carbon steel for mechanical structure (S15C, S55C) and aluminum alloy were used as the mold 7, pod 4 and cylinder 5, and azodicarbonamide (ADCA) was used as the foaming agent. As other blowing agents, NN′-dinitrosopentamethylenetetramine (DPT), 4,4′-oxybis (benzenesulfonylhydraside (OBSH), sodium hydrogen carbonate is also possible (including microballoons), and the result There is no change.

  Each component of Examples 1 to 14 shown in Table 1 was kneaded with a 6-inch open roll to obtain an unfoamed rubber material sr of each example. Next, by the manufacturing method according to the present embodiment, the outer rubber layer of each example prepared in advance was set in the mold using the mold shown in Table 1 and obtained in advance. After the unfoamed rubber material sr is set in the preliminary chamber 3 of the injection part 2, it is injected into the mold in which the relief holes of each example are processed, press-molded at 160 ° C., and vulcanized and foamed to supply two layers. A paper roller (rubber having a two-layer structure) 51 was produced.

(Comparative Examples 1-5)
Using each component of Comparative Examples 1 to 5 shown in Table 1, except using the mold shown in Table 1 having upper and lower molds different in shape, number, area ratio, and depth from Examples 1 to 14. In the same manner as in Examples 1 to 14, a two-layer paper feed roller (two-layer rubber) was produced.

(Comparative Example 6)
Using the components of Comparative Example 6 shown in Table 1 and using a mold having upper and lower molds having shapes, numbers, area ratios, and depths different from those of Examples 1 to 14, the outer layer and the inner layer were produced separately. Thereafter, these were bonded with an adhesive to produce a two-layer paper feed roller (two-layer rubber).

  In addition, the results of tests conducted on these two-layer paper feed rollers are shown.

  The roller hardness was measured by applying a load of 1 kg using an Asker C hardness meter. The adhesion evaluation between the outer rubber layer and the inner foam rubber layer was measured by whether the two-layer paper feed roller was peeled from the interface before the outer layer was destroyed.

  The friction coefficient was evaluated by the following method. A predetermined sheet having a load cell connected between a test roller fixed to the drive shaft and a free drum applied with a constant load (W) was sandwiched, and then the test roller was rotated to measure the frictional force (F). The friction coefficient was calculated by inputting the friction force (F) and the load (W) into the formula = F / W.

  The foaming ratio was calculated from true specific gravity (specific gravity when not foamed) / apparent specific gravity (specific gravity of foamed rubber) by measuring the specific gravity by cutting the foam rubber part from the two-layer paper feed roller. The average bubble diameter was an average value obtained for 15 bubbles from the measured bubble diameter. The bubble state was observed using an optical microscope.

  Since it is difficult to quantify the nip width by direct observation, an autograph (manufactured by Toyo Seiki Co., Ltd.) is used to measure the load (N) when the roller outer periphery is compressed by 1 mm while shifting the phase by 90 °. The sponge stability in the circumferential direction was confirmed.

  The separation performance confirmation test uses a scanner FI-5650C manufactured by Fujitsu Ltd., and through 200 sheets of plain paper, carbonless paper, and cardboard, are there any problems with non-feeding, double feeding, multiple feeding, and other paper passing? confirmed.

  In each of the two-layer paper feed rollers of Examples 1 to 14 shown in Table 1, the nip width is stable, the separation performance of each sheet is good, the adhesion between the outer layer and the inner layer is good, and the friction coefficient is also good. It is high.

  In Comparative Example 1 manufactured with a mold having a relief hole size of φ0.5 and a number of holes of 40, the unfoamed rubber material sr does not foam in the mold, and is suddenly foamed and destroyed when taken out. .

  Comparative Example 2 produced with a die having a relief hole size of φ2 and 6 holes, Comparative Example 3 produced with a die having a relief hole size of φ3 and 2 holes, Although the width is stable, the expansion ratio is low and the separation performance is poor.

  In Comparative Example 4 manufactured with a mold having a relief hole depth of 20 mm, the bubble state is non-uniform and the nip width is not stable.

  In Comparative Example 5 in which the thickness of the outer rubber layer is 4 mm, the nip width is stable, but the load when compressed by 1 mm is large and the separation performance is poor.

  In Comparative Example 6 in which an outer rubber layer and an inner foamed rubber layer were separately prepared and post-adhesion was performed using an adhesive, peeling was performed from the interface in the adhesive evaluation.

Fig.1 (a) is an external view of the manufacturing apparatus of foamed rubber used for the manufacturing method of foamed rubber which is a suitable embodiment of this invention, FIG.1 (b) is the fragmentary sectional view. It is a decomposition | disassembly partial sectional view of the manufacturing apparatus of the foamed rubber shown in FIG. It is sectional drawing which shows 1 process of the manufacturing method of the foamed rubber which is suitable embodiment of this invention. It is sectional drawing which shows 1 process of the manufacturing method of the foam rubber performed following FIG. It is sectional drawing which shows 1 process of the manufacturing method of the foamed rubber performed following FIG. 6A is a top view showing the state of the upper mold in FIG. 4, and FIG. 6B is a bottom view showing the state of the lower mold in FIG. 7 (a) to 7 (b) are plan views of an upper mold using various escape holes. 8 (a) to 8 (e) are diagrams for explaining a conventional method for producing foamed rubber.

Explanation of symbols

1 Foam rubber manufacturing equipment 7 Mold
7u Upper mold 7m Middle mold 7d Lower mold 31 Rubber layer 32 Foamed rubber layer sr Solid unfoamed rubber material r Liquid unfoamed rubber material

Claims (2)

In a foamed rubber manufacturing apparatus in which a foamed rubber layer is molded in close contact with a pre-molded rubber layer, a preliminary chamber for placing a solid unfoamed rubber material and heating and pressurizing it into a liquid state, and The rubber layer is set and the liquid non-foamed rubber material is injected inside the spare chamber, and the injected non-foamed rubber material is vulcanized and foamed to form the foamed rubber layer. And a molding chamber for adhering to the rubber layer ,
A pod in which the preliminary chamber is formed, a cylinder which is stacked on the pod and pressurizes solid unfoamed rubber material, and a cylindrical core in which the pod is stacked on top to form the molding chamber A mold, and a cylindrical upper mold and a cylindrical lower mold that are respectively stacked above and below the middle mold;
The upper mold and the lower mold are escape holes that pass through the upper and lower molds and allow excess unfoamed rubber to escape, and the number of holes, the hole diameter, and the hole shape are set according to the foaming degree of the foamed rubber layer. Each relief hole is formed,
The total hole area S1 of all upper relief holes formed in the upper mold, or the total hole area S1 of all lower relief holes formed in the lower mold, and the cross section of the foam rubber layer (sponge An apparatus for producing foamed rubber, characterized in that an area ratio (S1 / S2) to an area S2 of (cross section) is 10 to 80% . The upper mold and the lower mold, the foamed rubber manufacturing apparatus excess unfoamed rubber according to claim 1, wherein the escaping groove escape the mold outside were formed.

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