JP2006123202A - Casting machine and liquid substance supply method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a casting machine capable of casting a raw material liquid substance without exerting an effect on the material of a supply tank even if the temperature of the raw material liquid substance of the supply tank is set slightly lower and the temperature of the piping going toward a mixing chamber through a metering pump is set slightly higher in order to increase the reaction speed of a urethane, and a liquid substance supply method. <P>SOLUTION: In the casting machine having a route, which discharges a definite amount of the raw material liquid substance to the mixing chamber from the supply tank of the raw material liquid substance through piping by the metering pump, and a route for circulating the raw material liquid substance without discharging it to the mixing chamber, the circulating route has a liquid circulating confluent part between the supply tank and the metering pump. The liquid substance supply method is also disclosed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a liquid material such as liquid urethane resin is discharged into a mixing chamber by a metering pump, mixed in the mixing chamber, poured into a mold, and circulated without stopping the metering pump when injection is not necessary. The present invention relates to a casting machine and a liquid supply method.

  The electrophotographic blade is used to remove excess toner adhering to the surface of the photoreceptor after transfer in a copying machine or printer (cleaning blade) or to form a toner having a uniform film thickness on the developing carrier. (Developing blades) are used, but these blades are manufactured using polyurethane or the like as a raw material. In other words, in the case of polyurethane, the main component consisting of an isocyanate component and the curing agent consisting of a polyol component are put into the supply tank of the casting machine, preheated and degassed, then discharged into the mixing chamber by a metering pump, and mixed and stirred. Thereafter, the mixed solution is poured into a predetermined mold, and is allowed to undergo a curing reaction in the mold for a predetermined time, and then demolded and cut to obtain the cleaning blade and the like.

  By the way, although the polyurethane is continuously injected into the mold, if there is a time lag between the casting mold and the next casting mold, the polyurethane must be shot in a loss. This leads to material loss and goes against the recent trend of lower costs and reduced emissions. Also, if the metering pump is stopped to eliminate this material loss, there is a problem that the discharge amount is not stable and the ratio of the main agent and the curing agent changes at the initial stage of stop and start. In particular, in the case of a cleaning blade, when this ratio changes, the urethane rubber properties such as hardness and tensile properties change, that is, defective cleaning such as edge chipping and slipping occurs during use for electrophotography. Therefore, as described in Patent Document 1, discharge circulation is repeated without stopping the metering pump, and pressure sensors are further provided on the forward path side from the tank to the mixing chamber in the circulation path and on the return path side from the mixing chamber to the tank. There is disclosed a discharge method of providing and detecting and controlling pressure during discharge and circulation.

  In order to reduce the cost in recent years, it is also necessary to shorten the line cycle by shortening the time (curing time) from the injection of urethane into the mold to the demolding. For that purpose, there are a method of increasing the temperature of the mold by adding a catalyst to the curing agent (for example, Patent Document 2) and a method of increasing the temperature of the mold, but in order to accelerate the curing reaction, the material temperature must be increased. It is also important.

  However, according to the conventional liquid material supply method toward the tank, a predetermined hardness is obtained in the blade produced at the initial stage of starting the raw material liquid material, but there is a problem that the blade hardness gradually decreases. Therefore, it is desirable to set the raw material liquid temperature in the supply tank low, set the pipe temperature going to the mixing chamber through the metering pump high, and increase the raw material liquid temperature in the piping to mix at a high temperature in the mixing chamber. ing.

However, in the raw material liquid circulation type casting machine that returns to the conventional tank, if the discharge to the mixing chamber and the circulation to the tank are repeated, the temperature of the raw material liquid in the tank eventually becomes high. Even if another is set, the meaning is lost.
JP-A-6-210150 (5th page, FIG. 1) JP 2001-318569 A (Page 6, Table 1)

  The object of the present invention has been made in view of the above points, and in order to increase the reaction rate of urethane, the raw material liquid temperature of the supply tank is set lower, and the piping temperature toward the mixing chamber through the metering pump is set higher. Even so, it is an object of the present invention to provide a casting machine and a liquid material supply method capable of casting without affecting the material of the supply tank.

  According to the present invention, there are a path for discharging a predetermined amount of the liquid material from the raw material liquid supply tank to the mixing chamber by a metering pump via a pipe, and a path for circulating the liquid material without being discharged into the mixing chamber. A casting machine is provided, wherein the circulation path has a liquid circulation junction between the supply tank and the metering pump.

Further, according to the present invention, there is provided a liquid supply method for discharging a predetermined amount of the raw material liquid material from the raw material liquid material supply tank to the mixing chamber by a metering pump via a pipe, and comprising the following three steps:
(1) The pressure value of the pressure sensor St installed in the supply tank is smaller than the pressure value when the discharge circulation switching valve of the discharge circulation unit of the pressure sensor Sc installed in the discharge circulation unit is switched to circulation. Adjusting process,
(2) A step of setting the pressure difference (Pc−Pt) between the pressure value (Pc) of the discharge circulation unit and the pressure value (Pt) of the supply tank to be a value larger than 0.01 MPa and smaller than 1.5 MPa. ,
(3) a step of switching to discharge to the mixing chamber and circulation to the metering pump side;
The liquid supply method characterized by including this is provided.

  According to the casting machine and the liquid supply method of the present invention having the above-described configuration, in order to increase the reaction rate of urethane, the raw material liquid temperature of the supply tank is set low, and the piping temperature toward the mixing chamber through the metering pump Casting machine and liquid material supply method that can be cast without affecting the material of the supply tank because there is a liquid circulation junction between the supply tank and the metering pump It became possible to provide.

  The present invention has a path for discharging a fixed amount of the raw material liquid material from the raw material liquid supply tank to the mixing chamber by a metering pump via a pipe, and a path for circulating the raw material liquid material without being discharged to the mixing chamber. In the casting machine, the circulation path is a casting machine having a liquid circulation merging portion between the supply tank and the metering pump. In the circulation path, a discharge circulation switching valve, a pressure sensor, and a pressure adjusting means for switching between discharge to the mixing chamber and circulation to the metering pump side are arranged, and this is discharged. A plurality of circulation units are formed and arranged so that they can be discharged into the mixing chamber.

  Below, the liquid substance supply method to the casting machine concerning this invention is demonstrated based on FIG.

  FIG. 1 is an overall view showing an embodiment of an apparatus for supplying urethane elastomer to a casting machine. As shown in FIG. 1, a urethane elastomer is injected into the mold from the discharge port of the casting machine, and a cleaning blade is formed.

  The raw material liquid used in the present invention is a thermosetting urethane resin liquid in which an isocyanate compound (liquid A) as a main component and a polyol compound (liquid B) as a curing agent are mixed with a mixer. Both the A-system liquid material and the B-system liquid material are discharged from the supply tank to the mixing chamber by the metering pump of the supply tank. Each raw material liquid is degassed under reduced pressure and then purged with an inert gas. At this time, nitrogen, argon, or the like may be used as the inert gas.

  A liquid feed pipe 2 connects the supply tank 1 and the mixing chamber 17, and a liquid return pipe 5 connects halfway between the mixing chamber 17 and the liquid feed pipe 2, and a metering pump 6 is interposed in the liquid feed pipe 2. The metering pump referred to here may be any pump that does not pulsate and discharges a metered liquid in one pulse.

  The supply tank and the liquid feed pipe are always kept at a constant temperature. As a means for keeping the temperature constant, for example, flowing constant temperature water from a constant temperature layer to a serpentine tube or the like and placing it in contact with the liquid feeding tube is performed. The supply tank generally has, for example, a generally stainless steel cylindrical shape with a conical lower portion, and the liquid is discharged from the lowermost portion. As for the shape, any structure that does not cause retention of the liquid raw material may be used.

  Next, a liquid supply method for the casting machine having the above configuration will be described.

  In FIG. 1, the liquid A is discharged from the supply tank 1 to the mixing chamber 17 via the discharge circulation switching valve 4 by the metering pump 6, and when there is no need to discharge, the discharge circulation switching valve 4 is switched and the liquid A is liquidated. It is sent to the liquid circulation junction 7 by the return pipe 5 and the circulation is repeated by the metering pump 6. What is necessary is just to switch the discharge circulation switching valve 4 at the time of re-discharge.

  At this time, the pressure in the supply tank is an inert gas (0.05 MPa), and the liquid feed pipe and the pump are pumped at this pressure value (Pt). The pressure in the supply tank may be a pressure sufficient to pump the liquid A to the liquid feed pipe and the pump. The pressure value (Pt) of the pressure sensor St installed on the supply tank side is the pressure value when the discharge / circulation switching valve of the discharge circulation unit of the pressure sensor Sc installed on the discharge circulation unit is switched to circulation ( Smaller than Pc). The pressure value (Pt) on the supply tank side is preferably greater than 0 MPa and 0.1 MPa or less, more preferably 0.05 to 0.1 MPa, and the pressure value (Pc) of the discharge circulation unit is preferably 0. 0.1 to 1.5 MPa, more preferably 0.5 to 1.0 MPa, and Pc—Pt is preferably greater than 0.01 MPa and less than 1.5 MPa. At this time, if Pc is higher than 1.5 MPa, the liquid material may leak from the mixing chamber upper seal. After the metering pump, the pressure value is adjusted using a pressure adjusting means so that the pressure value becomes constant (a value larger than 0.01 MPa and smaller than 1.5 MPa).

  At the time of discharge, the liquid material A is fed from the supply tank 1 to the mixing chamber 17 by the metering pump 6 through the liquid feed pipe 2, mixed, and then discharged from the discharge nozzle in an appropriate amount. However, when the discharge circulation switching valve for switching to the discharge to the mixing chamber and the circulation to the metering pump side is switched to the circulation side, the pressure value (Pt) of the supply tank becomes the pressure value (Pc) of the discharge circulation unit. ) The pressure is adjusted to be smaller, and the pressure difference (Pc−Pt) is in the range of a value larger than 0.01 MPa and smaller than 1.5 MPa. Is preferentially circulated and discharged from a liquid material that has been circulated repeatedly during re-discharge.

  As the discharge circulation switching valve, a structure in which the liquid circuit is switched for a very short time is selected. In addition, since it is used for liquid circulation of paint, it is required that there is no or very little wear at the valve switching structure. Therefore, the material of the sliding mechanism portion of the valve is preferably one having a low wear or high lubricity surface. Examples thereof include those coated with a fluorine-based resin such as polytetrafluoroethylene and organic silane.

  The pressure adjusting means is provided between the discharge / circulation switching valve and the liquid circulation merging section. When the pressure at the time of circulation is different from the pressure at the time of discharge, the pressure sensor installed in the discharge circulation unit has a pressure value at the time of discharge ( Adjustment is performed such that the difference between Pd) and the pressure during circulation (Pc) is preferably 0.1 MPa or less, more preferably 0.05 MPa or less. As an example of the present invention, a screw adjustment type was adopted.

  By the way, in the said embodiment, although only the conveyance method of the liquid A was shown, you may apply to both or only one side.

  Also, if the material temperature of the supply tank is set low, the piping temperature is set high while going to the mixing chamber through the metering pump, and if the reaction is carried out at a high temperature in the mixing chamber, the reaction rate is increased and the production efficiency is increased. Can do. At this time, if the circulation method of the present invention is used, deterioration of the raw material is reduced.

  As an example, a path connecting the front and rear of the metering pump as shown in FIG. 1 is a circulation path. The circulation path includes a pressure sensor, discharge into the mixing chamber, and the metering path. A discharge circulation switching valve that switches to circulation to the pump side and a pressure adjusting means is used. As a comparative example, the return of circulation as shown in FIG. 2 goes directly to the supply tank. .

Example 1
The casting in FIG. 1 is performed at a supply tank temperature of 60 ° C., a mixing chamber raw material temperature of 90 ° C., a tank pressure (Pt) of 0.05 MPa, a circulation pressure (Pc) of 0.8 MPa, and a discharge pressure (Pd) of 0.7 MPa. Urethane was cast using an apparatus to prepare a cleaning blade.

(Comparative Example 1)
The casting apparatus shown in FIG. 2 has a tank internal temperature of 90 ° C., a mixing chamber raw material temperature of 90 ° C., a tank pressure (Pt) of 0.05 MPa, a circulation pressure (Pc) of 0.9 MPa, and a discharge pressure (Pd) of 0.9 MPa. Urethane was cast using to prepare a cleaning blade.

(Comparative Example 2)
The casting apparatus shown in FIG. 2 has a temperature in the tank of 60 ° C., a raw material temperature in the mixing chamber of 60 ° C., a tank pressure (Pt) of 0.05 MPa, a circulation pressure (Pc) of 1.0 MPa, and a discharge pressure (Pd) of 1.1 MPa. Urethane was cast using a to prepare a cleaning blade.

  The cleaning blade produced in this manner was evaluated for the curing and demolding time during the production process and the hardness after aging. The results are shown in Table 1. The above characteristics were evaluated as follows.

<Curing demolding time>
The raw material mixture was poured into a mold at 130 ° C. to cause a curing reaction, and then the time until the cured product was demolded was measured. As a measure of the time until demolding, the hardness at demolding was set to 40 ° or more.

<Blade hardness>
The liquid was put into the supply tank, and immediately after starting casting, the blade was sampled after 3 hours and 12 hours, and after aging at room temperature for 1 day, the urethane rubber hardness was measured. The hardness (IRHD) was measured based on JIS K 6253 using a Wallace microhardness meter manufactured by Wallace (HW WALLACE).

  The influence on the raw material liquid in the constituent devices of Examples and Comparative Examples was evaluated by blade hardness. A predetermined hardness is obtained in the blade produced in the initial stage of charging the raw material, but the blade hardness gradually decreases. The change in hardness was examined for two casting apparatuses with different liquid circulation methods.

  From the results shown in Table 1, in Example 1, when the raw material temperature in the mixing chamber is raised from the temperature in the tank, the reaction rate is increased and the demolding time is shortened to 1 minute. Furthermore, there was no change in hardness after 3 hours and 12 hours after the start of casting.

  On the other hand, in Comparative Example 1, the temperature in the tank and the mixing chamber was set to 90 ° C., and the reaction rate was as fast as 1 minute, but the hardness change was large. Here, it has been found that when the blade hardness falls below 65 °, cleaning failure occurs. Further, in Comparative Example 2, the temperature in the tank and the mixing chamber was set to 60 ° C., and the reaction rate was as slow as 10 minutes although there was no change in the hardness of the blade.

It is the schematic explaining the liquid supply method to the casting machine concerning this invention. It is the schematic explaining the liquid supply method to the conventional casting machine.

1 Supply tank A
2 Liquid feed pipe 3 Discharge liquid 4 Discharge circulation switching valve 5 Liquid return pipe 6 Metering pump 7 Liquid circulation junction 8 Pressure sensor Sc
9 Pressure adjusting screw 10 Pressure sensor St
11 Supply tank B
12 Liquid feed pipe 13 Discharge circulation switching valve 14 Liquid return pipe 15 Metering pump 16 Head cover 17 Mixing chamber 18 Discharge port 19 Liquid circulation confluence 20 Pressure sensor Sc
21 Pressure adjusting screw 22 Pressure sensor St

Claims (6)

  A casting machine having a path for discharging a certain amount of the liquid material from the raw material liquid supply tank to the mixing chamber by a metering pump via a pipe and a path for circulating the liquid material without being discharged into the mixing chamber. The casting machine is characterized in that the circulation path has a liquid circulation junction between the supply tank and the metering pump.   In the circulation path, a discharge circulation switching valve for switching between discharge and circulation to the mixing chamber, a pressure sensor, and pressure adjusting means are arranged, and a plurality of discharge circulation units are formed. The casting machine according to claim 1, wherein the casting machine is disposed so as to be able to discharge into the mixing chamber.   The pressure value (Pt) of the pressure sensor St installed in the supply tank is the pressure value (Pc) when the discharge circulation switching valve of the discharge circulation unit of the pressure sensor Sc installed in the discharge circulation unit is switched to circulation. The casting machine according to claim 1 or 2, which is smaller.   The pressure value (Pt) of the supply tank is greater than 0 MPa and 0.1 MPa or less, the pressure value (Pc) of the discharge circulation unit is 0.1 to 1.5 MPa, and Pc-Pt is greater than 0.01 MPa. The casting machine according to any one of claims 1 to 3, which has a value smaller than 5 MPa.   The pressure sensor installed in the said discharge circulation unit WHEREIN: Pressure adjustment was carried out by the said pressure adjustment means so that the difference of the pressure value (Pd) at the time of discharge and the pressure (Pc) at the time of circulation might be 0.1 Mpa or less. Casting machine. A liquid material supply method for discharging a certain amount of the raw material liquid material from the raw material liquid material supply tank to the mixing chamber by a metering pump via a pipe, comprising the following three steps:
(1) The pressure value (Pt) of the pressure sensor St installed in the supply tank is the pressure value when the discharge circulation switching valve of the discharge circulation unit of the pressure sensor Sc installed in the discharge circulation unit is switched to circulation ( Adjusting the pressure smaller than Pc),
(2) A step of setting the pressure difference (Pc−Pt) between the pressure value (Pc) of the discharge circulation unit and the pressure value (Pt) of the supply tank to be a value larger than 0.01 MPa and smaller than 1.5 MPa. ,
(3) a step of switching to discharge to the mixing chamber and circulation to the metering pump side;
The liquid supply method characterized by including.

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