JPH05220768A - Foamed resin mixing device - Google Patents

Abstract

PURPOSE:To dispense with a washing process during operation, to enable long- time continuous operation and to densify and stabilize foam cells. CONSTITUTION:A mixing device has a mixing chamber 20, a plurality of resin supply passages 50, 60 supplying a plurality of liquid resins reacted with each other to form a foamed resin to the mixing chamber 20 and a gas supply passage 70 supplying gas to the mixing chamber 20 and, when a plurality of the liquid resins are mixed within the mixing chamber 20, the gas is supplied into the mixing chamber 20 from the gas supply passage 70 to be mixed with the liquid resins. The gas bubbles in the mixed resin become foam cell forming unclei to stabilize and densify foam cells.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed resin mixing apparatus used for manufacturing foamed products such as automobile headrests and seats.

[0002]

2. Description of the Related Art Foamed resin products such as headrests and seats are mainly composed of polyether polyol in a molding die.
It is manufactured by urethane foam molding in which a liquid and a liquid B mainly containing polyisocyanate are reacted with a foaming agent. It is necessary that the liquid A and the liquid B are mixed sufficiently uniformly, but since the reaction rapidly proceeds immediately after mixing, they must be separately separated until just before mixing.

Therefore, conventionally, the liquid A and the liquid B are respectively introduced into a foaming resin mixing device, and after being sufficiently uniformly mixed by the mixing device, they are supplied from a supply device to a molding die. As the foamed resin mixing device, there are known two types of devices, a low pressure type in which both components are stirred and mixed by the rotation of a blade, and a high pressure type in which both components are mixed by collision in a high pressure state. Among them, the low-pressure type mixing device includes a mixing chamber, two resin supply paths for supplying the liquid A and the liquid B to the mixing chamber, a stirring means for stirring the liquid A and the liquid B supplied into the mixing chamber, and a mixing unit. It is composed of a cleaning liquid supply passage for supplying the cleaning liquid into the room.

A predetermined amount of A is supplied from the two resin supply paths.
The liquid and the liquid B are supplied into the mixing chamber together with the foaming agent. In the mixing chamber, it is sufficiently mixed by a stirring blade, and a predetermined amount of the mixed resin is immediately injected into the molding die. Then, the foaming reaction and the urethane reaction proceed almost at the same time in the mold, and foam molding is performed. On the other hand, in the mixing device in which the mixed resin is discharged from the mixing chamber, the mixed resin adheres to the inner wall of the mixing chamber, etc., and therefore reacts and solidifies when left alone. Therefore, molding is continuously performed by repeating resin supply-mixing-discharging-resin supply so that a new resin is almost always supplied into the mixing chamber. If you do this,
Since the mixed resin adhering to the inner wall of the mixing chamber is mixed with new supply resin and injected into the molding die at the time of molding from the next time, there is no problem of solidification in the mixing chamber.

After the continuous molding is completed, the cleaning solvent is supplied from the cleaning liquid supply passage to clean the mixed resin adhering to the inner wall of the mixing chamber. In addition, the high-pressure mixer is 140
Both components are injected into the mixing chamber at a high pressure of about 160 kg / cm ² so as to collide with each other in front of each other, mixed by the collision and discharged from the nozzle. Then, the resin remaining in the path is scraped off and discharged by the cleaning rod sliding in the path. Therefore, according to the high-pressure mixer, the stirring blade is not required, the apparatus can be downsized, and the cleaning solvent can be eliminated.

[0006]

However, when molding is continuously carried out using the above-mentioned low-pressure type mixing apparatus, the foam cells of the foam-molded article obtained by repeating the molding a large number of times gradually change to the final cell. However, there is a problem that foam cells are crushed. Therefore, it is necessary to periodically stop the continuous operation, supply the cleaning liquid from the cleaning liquid supply passage and perform the cleaning process to restore the initial state, and the production efficiency is reduced accordingly.

Further, even in the high pressure type mixing device, there is a problem that the size of the foaming cell and the foaming density vary during the continuous operation, though not to the extent of the low pressure type. The present invention has been made in view of such circumstances, and it is an object of the present invention to eliminate the need for a washing step in the middle of the process, enable continuous operation for a long time, and to make a foam cell dense and stable.

[0008]

The foamed resin mixing apparatus of the present invention for solving the above-mentioned problems includes a mixing chamber and a plurality of resins for supplying a plurality of liquid resins each of which reacts with each other to form a foamed resin into the mixing chamber. A gas supply path and a gas supply path for supplying a gas to the mixing chamber are provided, and when a plurality of liquid resins are mixed in the mixing chamber, the gas is supplied from the gas supply path into the mixing chamber and mixed together. It is characterized by being done.

As the kind of gas, any gas that is irrelevant to the reaction of the resin and is harmless can be used, and air is generally used. The supply volume of this gas per unit time is 15 times the supply volume of all the resins supplied to the mixing chamber per unit time.
It is preferably in the range of ˜65%. If it is less than this range, the effect cannot be obtained, and if it is too large, problems such as poor enlargement of the foam cells and scattering of the resin liquid during ejection occur.

The opening of the gas supply passage may be provided at any position between the mixing start position and the mixing end position where at least a plurality of liquid resins are mixed.

[0011]

In the foamed resin mixing apparatus of the present invention, the liquid resins involved in the reaction are supplied from the respective resin supply paths into the respective mixing chambers and are sufficiently uniformly mixed. At the time of this mixing, a predetermined amount of gas is supplied from the gas supply path, and the mixed resin in which the gas is uniformly mixed is injected into the molding die to perform foam molding. It is considered that the fine air bubbles of the gas thus mixed serve as the core of foam cell formation during foaming, and the foam cells become dense and stable.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples. (Embodiment 1) FIGS. 1 to 4 show a foamed resin mixing apparatus according to an embodiment of the present invention. This foamed resin mixing device is a low-pressure mixing device, and includes a base 1 fixed to a molding device, a mixing part 2 fixed to one end of the base 1, a nozzle 3 fixed to the tip of the mixing part 2, and a base part. Motor 4 held on the other end side of 1
An A liquid supply part 5 and a B liquid supply part 6 for supplying a liquid resin to the base 1, and an air supply part 7 for supplying air to the base 1.
The cleaning liquid supply unit 8 supplies a cleaning solvent to the base 1.

The base 1 is provided with an A liquid supply passage 50 and a B liquid supply passage 60 extending from one end to the other end. At one end of the A liquid supply passage 50 and the B liquid supply passage 60,
The liquid supply unit 5 and the B liquid supply unit 6 are connected. The other ends of the A liquid supply passage 50 and the B liquid supply passage 60 are in communication with the mixing chamber 20 formed in the mixing section 2. And A
Needle valves 51 and 61 are arranged at the other ends of the liquid supply passage 50 and the B liquid supply passage 60, respectively, so that the supply amounts of the A liquid and the B liquid can be adjusted independently. The openings on the mixing chamber 20 side of the A liquid supply passage 50 and the B liquid supply passage 60 are
They are provided opposite each other from 180 degrees,
The discharged liquid A and liquid B are configured so as to collide with each other and be easily mixed.

Further, the base portion 1 is formed with a gas-liquid supply passage 70 which opens toward the upper peripheral surface and extends toward the mixing chamber 20 to connect the outside with the mixing chamber 20. Then, the air supply unit 7 is provided to the outside opening of the gas-liquid supply passage 70 via the base 71.
And the cleaning liquid supply unit 8 are connected. The opening of the gas-liquid supply passage 70 on the mixing chamber 20 side is located in the vicinity of the opening of the A-liquid supply passage 50 and the B-liquid supply passage 60 on the mixing chamber 20 side, and the axial directions are the A-liquid supply passage 50 and the B-liquid supply. It is orthogonal to the axial direction of the opening of the passage 60. That is, the air or the cleaning solvent ejected from the gas-liquid supply passage 70 is configured to eject orthogonally toward the respective resin streams ejected from the A-liquid supply passage 50 and the B-liquid supply passage 60. ..

A drive shaft 40 extending from the motor 4 passes through the base 1, and the tip of the drive shaft 40 is located in the mixing chamber 20. A stirring blade 41 is fixed to the tip of the drive shaft 40, and is configured to rotate in the mixing chamber 20 by driving the motor 4 to stir the mixing chamber. Air supply unit 7
Has a regulator 72 for adjusting the pressure of air sent from a compressor (not shown) and a solenoid valve 73, and turns on the supply of air to the gas-liquid supply passage 70 by controlling the solenoid valve 73 by a controller (not shown). OF
F control. Further, the cleaning liquid supply unit 8 is a solenoid valve 8
Controlling the solenoid valve 80 by a control device (not shown), the cleaning solvent sent from a pump (not shown) to the gas-liquid supply passage 70, the A liquid supply passage 50, and the B liquid supply passage 60 to the mixing chamber 20 side opening. Control supply. In addition, check valves 81 and 82 are arranged in the cleaning liquid supply unit 8 to prevent backflow of the cleaning solvent and air.

A method for molding urethane foam using the foamed resin mixing apparatus configured as described above will be described below. First, the motor 4 is driven, and in this state, the A liquid mainly containing polyether and the B liquid mainly containing polyisocyanate are supplied from the A liquid supplying section 5 and the B liquid supplying section 6 respectively to the A solution supplying path 50 and It is supplied to the B liquid supply path 60. Then, the total of the liquid A and the liquid B is supplied into the mixing chamber 20 at a flow rate of 120 cm ³ / sec, which is adjusted by the needle valves 51 and 61 to have a predetermined mixing ratio.

At this time, the solenoid valve 73 is turned on and the solenoid valve 80 is turned off. At the same time, the pressure of 0.2 to 0.3 kg / cm ² (50 cm
An air flow of ³ / sec) is supplied to the mixing chamber 20. Mixing chamber 2
At 0, the liquid A, the liquid B, and the air flow are mixed by the rotation of the stirring blade 41, and the mixed resin containing uniform bubbles is discharged from the nozzle 3 to the molding die.

When a predetermined amount of the mixed resin is discharged, the supply of the liquids A and B is stopped and the solenoid valve 7
3 is turned off and the air supply is also stopped. Then, when the injection port of the next mold moves to the position facing the nozzle 3, the liquids A, B and air are supplied again in the same manner, and mixing is performed for the next molding. Then, molding was continuously performed under the condition that the interval from the mixing step to the next mixing step was 4 to 5 seconds. In addition, in the conventional method of mixing and discharging without supplying air using the same apparatus, molding failure occurred when molding was continuously performed about 5 times or more. Therefore, after the continuous molding is performed less than that number of times, the process of stopping the supply of the liquid A, the liquid B and the air and supplying the cleaning solvent for cleaning is performed.
However, according to the method of this example, even if molding was performed 25 times or more continuously, no change in the foam cells of the molded product was observed during that time, and stable molding was possible. The reason why the foamed cells are stabilized in this way is not clear, but it is considered that the bubbles uniformly mixed in the resin serve as the nucleus of foamed cell formation during foaming.

At the end of the molding operation, the supply of A liquid, B liquid and air is stopped and the solenoid valve 80
Is turned on to supply the cleaning solvent to the mixing chamber 20, the end of the A liquid supply passage 50 and the end of the B liquid supply passage 60, and the inner walls of these and the surface of the stirring blade 41 are cleaned to complete the work. (Embodiment 2) A second embodiment shown in FIGS. 5 to 7 is one in which the present invention is applied to a high pressure mixer. Portions having the same functions as those in the first embodiment will be described with the same numbers as in the first embodiment.

A nozzle 3, a first hydraulic cylinder 11 and a second hydraulic cylinder 12 are fixed to the base 1. The axial directions of the first hydraulic cylinder 11 and the second hydraulic cylinder 12 are orthogonal to each other. The nozzle hole 30 of the nozzle 3 penetrates the base portion 1, and the cleaning piston rod 13 of the first cylinder 11 is slidably engaged with the nozzle hole 30. The piston rod 14 of the second cylinder 12 is
It is slidably engaged with the resin supply passage 10 communicating with the nozzle hole 30.

A mixing chamber 20 is formed in the resin supply passage 10 by opening an A liquid supply passage 50 and a B liquid supply passage 60 so as to face each other. An air supply passage 70 extending in the axial direction is formed in the center of the piston rod 14,
An air supply unit 7 similar to that of the first embodiment is connected to the end of the air supply path 70. The tip of the air supply path 70 is open at the tip of the piston rod 14 so that air can be supplied to the mixing chamber 20. A pair of symmetrical notches 15 are formed on the outer peripheral surface of the piston rod 14.

In the mixing apparatus of the present embodiment constructed as described above, the A liquid and the B liquid are supplied to the A liquid supply passage 50 and the B liquid supply passage 60, respectively, at a high pressure of 150 kg / cm ² . Then, in a state where the nozzle 3 does not discharge, as shown in FIG. 6, the piston rod 14 advances to close the mixing chamber 20. At this time, the A liquid supply path 50 and the B liquid supply path 60
Respectively open in the notches 15 and the notches 1
A liquid circulation path 52 and a B liquid circulation path 62 communicate with 5 respectively. Therefore, the A liquid and the B liquid supplied from the A liquid supply passage 50 and the B liquid supply passage 60 have a pair of notches 1
5 to the A liquid circulation path 52 and the B liquid circulation path 62, and circulate in the closed circulation systems.

At the time of discharging from the nozzle 3, when the piston rod 14 retracts as shown in FIG. 7, the openings of the A liquid supply passage 50 and the B liquid supply passage 60 are exposed to the mixing chamber 20,
The high-pressure liquid A and liquid B are injected into the mixing chamber 20. Since the openings face each other, the liquids A and B collide vigorously and are mixed uniformly. At this time, 0.5 from the opening of the air supply passage 70 at the tip of the piston rod 14.
Since air is supplied at a pressure of about kg / cm ² ,
This air flow is supplied to the collision portion of the A liquid and the B liquid, and is mixed as fine bubbles in the mixed resin of the A liquid and the B liquid.

The mixed resin flows from the mixing chamber 20 into the nozzle hole 30 and is discharged from the nozzle 3. When a predetermined amount of the mixed resin is discharged, the piston rod 14 advances to close the mixing chamber 20 and discharge the residual resin in the mixing chamber 20 to the nozzle hole 30. Then, the cleaning piston rod 13 advances, the residual resin in the nozzle hole 30 is discharged from the nozzle 3, and one step is completed.

In the conventional high-pressure mixing apparatus, the foaming cells fluctuated due to the pressure fluctuations of the liquids A and B, but by supplying air into the mixing chamber 20 as in the present embodiment, it is stabilized. A densified foam cell was obtained.

[0026]

[Effects of the Invention] That is, according to the foamed resin mixing apparatus of the present invention, it is possible to manufacture a molded body having stable foamed cells even if it is continuously operated for a long time, and to eliminate the need for a washing step in the middle. As a result, productivity is improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the overall configuration of a foamed resin mixing apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

3 is an enlarged cross-sectional view of a main part of FIG. 1 viewed from the opposite side of FIG.

FIG. 4 is an enlarged explanatory view of a main part of FIG.

FIG. 5 is a cross-sectional view of essential parts of a foamed resin mixing apparatus according to a second embodiment of the present invention.

6 is an enlarged LL sectional view of FIG. 5 during circulation.

7 is an enlarged LL sectional view of FIG. 5 at the time of ejection.

[Explanation of symbols]

1: Base 2: Mixing part 3: Nozzle
4: Motor 20: Mixing chamber 30: Nozzle hole 41: Stirring blade 50, 60: Resin supply path 70: Gas-liquid supply path

Claims (1)

[Claims] 1. A mixing chamber, a plurality of resin supply paths for supplying a plurality of liquid resins each of which reacts to form a foamed resin into the mixing chamber, and a gas supply path for supplying a gas to the mixing chamber. When mixing a plurality of the liquid resins in the mixing chamber, the gas is supplied from the gas supply path into the mixing chamber to mix them together. ..