JP2709425B2 - Urethane foam resin mixing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a urethane foam resin mixing apparatus used for producing urethane foam products such as headrests and seats of automobiles.

[0002]

2. Description of the Related Art Foamed resin products such as headrests and sheets are mainly made of polyether polyol in a mold.
It is manufactured by urethane foam molding in which a liquid and a liquid B mainly containing polyisocyanate are reacted with a foaming agent. The solution A and the solution B need to be sufficiently homogeneously mixed, but the reaction proceeds rapidly immediately after the mixing, so that they must be separately separated until immediately before the mixing.

Therefore, conventionally, the liquid A and the liquid B are respectively introduced into a foamed resin mixing device, mixed sufficiently uniformly by the mixing device, and then supplied from a supply device to a molding die. As the foamed resin mixing apparatus, two types of apparatuses are known: a low-pressure type in which both components are agitated and mixed by rotation of a blade, and a high-pressure type in which both components are mixed by collision in a high pressure state. The low-pressure mixing apparatus includes a mixing chamber, two resin supply paths for supplying the liquid A and the liquid B to the mixing chamber, a stirring unit for stirring the liquid A and the liquid B supplied to the mixing chamber, A cleaning liquid supply path for supplying the cleaning liquid into the room.

A predetermined amount of A is supplied from 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, the mixture is sufficiently mixed by the stirring blade, and a predetermined amount of the mixed resin is immediately injected into the mold. Then, the foaming reaction and the urethane reaction proceed almost simultaneously in the mold, and foam molding is performed. On the other hand, in a mixing apparatus in which the mixed resin is discharged from the mixing chamber, the mixed resin adheres to the inner wall of the mixing chamber or the like, and thus reacts and solidifies when left unattended. Therefore, molding is continuously performed by repeating resin supply-mixing-discharge-resin supply so that a new resin is almost always supplied into the mixing chamber. If you do this,
The mixed resin adhering to the inner wall of the mixing chamber is mixed with the new supply resin and injected into the mold at the time of the next molding, so that there is no problem of solidification in the mixing chamber.

After the continuous molding is completed, a cleaning solvent is supplied from a cleaning liquid supply path, and the mixed resin adhering to the inner wall of the mixing chamber is cleaned. Also, the high-pressure mixing device is 140
The two components are injected into the mixing chamber at a high pressure of up to 160 kg / cm ² so as to collide with each other from the front, mixed by the collision, and discharged from the nozzle. The resin remaining in the path is scraped off by a cleaning rod sliding in the path and discharged. Therefore, according to the high-pressure mixing device, the stirring blade is not required, the device can be downsized, and the cleaning solvent can be unnecessary.

[0006]

However, in the case of performing continuous molding using the above-described low-pressure mixing apparatus, if the molding is repeated many times, the foam cells of the obtained foamed molded article gradually change, and the There was a problem that foam cells collapsed. Therefore, it is necessary to periodically stop the continuous operation, perform a step of supplying the cleaning liquid from the cleaning liquid supply path to perform the cleaning, and return to the initial state, and accordingly, the production efficiency is reduced.

[0007] The high-pressure mixing apparatus also has a problem that the size and foam density of the foam cells vary during continuous operation, although not as much as in the low-pressure mixer. The present invention has been made in view of such circumstances, and an object of the present invention is to eliminate the need for a washing step in the middle, to enable continuous operation for a long time, and to make the foam cell dense and stable.

[0008]

The urethane foam resin mixing apparatus according to the present invention for solving the above-mentioned problems comprises a mixing chamber and a plurality of liquid resins which respectively react to form a urethane foam resin into the mixing chamber. And a gas supply path for supplying gas to the mixing chamber, and when mixing a plurality of liquid resins in the mixing chamber, the gas is supplied from the gas supply path into the mixing chamber and mixed together. It is characterized by comprising.

Any kind of gas can be used as long as it is harmless and irrelevant to the reaction of the resin, and air is generally used. The supply volume per unit time of this gas is 15 times the supply volume per unit time of the total resin supplied to the mixing chamber.
Preferably, it is in the range of ~ 65%. If the amount is less than this range, the effect cannot be obtained, and if the amount is too large, problems such as poor enlargement of the foam cell and scattering of the resin liquid at the time of discharge occur.

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

[0011]

In the urethane foam resin mixing apparatus of the present invention, the liquid resins involved in the reaction are supplied into the mixing chambers from the respective resin supply paths, and are sufficiently uniformly mixed. During this mixing, a predetermined amount of gas is supplied from the gas supply path, and a mixed resin in which the gas is uniformly mixed is injected into a molding die to perform urethane foam molding. Thus, it is considered that fine bubbles of the mixed gas serve as nuclei for foam cell formation during foaming, and the foam cells are densified and stabilized.

[0012]

The present invention will be specifically described below with reference to examples. Example 1 FIGS. 1 to 4 show a urethane foam resin mixing apparatus according to an example of the present invention. This urethane foam resin mixing device is a low pressure type mixing device, and has a base 1 fixed to a molding device, and a base 1.
, A nozzle 3 fixed to the tip of the mixing unit 2, a motor 4 held at the other end of the base 1, and an A liquid supply unit for supplying a liquid resin to the base 1 5 and B
Liquid supply section 6 and air supply section 7 for supplying air to base 1
And a cleaning liquid supply unit 8 for supplying a cleaning solvent to the base 1.

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

The base 1 is provided with a gas-liquid supply passage 70 which opens toward the upper peripheral surface and extends toward the mixing chamber 20 and communicates the outside with the mixing chamber 20. An air supply unit 7 is provided at the outside opening of the gas-liquid supply path 70 through a base 71.
And the cleaning liquid supply unit 8 are connected. The opening of the gas-liquid supply path 70 on the mixing chamber 20 side is located near the opening of the A liquid supply path 50 and the B liquid supply path 60 on the mixing chamber 20 side, and the axial direction is the A liquid supply path 50 and the B liquid supply path. It is orthogonal to the axial direction of the opening of the passage 60. That is, the air or the cleaning solvent spouted from the gas-liquid supply path 70 is configured to spout orthogonally toward the respective resin flows discharged from the A-liquid supply path 50 and the B-liquid supply path 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 controls the supply of air to the gas-liquid supply path 70 by controlling the solenoid valve 73 by a control device (not shown). OF
Perform F control. The cleaning liquid supply unit 8 includes a solenoid valve 8.
0, and the control of the solenoid valve 80 by a control device (not shown) allows the cleaning solvent sent from a pump (not shown) to be supplied to the gas-liquid supply passage 70 and the openings of the A-liquid supply passage 50 and the B-liquid supply passage 60 to the mixing chamber 20 side. Control the supply. In addition, check valves 81 and 82 are disposed in the cleaning liquid supply unit 8 to prevent a back flow of the cleaning solvent and air.

A method for molding urethane foam using the urethane foam 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 composed of polyether and the B liquid mainly composed of polyisocyanate are supplied from the A liquid supply unit 5 and the B liquid supply unit 6 to the A liquid supply paths 50 and 50, respectively. The liquid is supplied to the B liquid supply path 60. Then, the mixture is adjusted by the needle valves 51 and 61 so as to have a predetermined mixing ratio, and 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.

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

When a predetermined amount of the mixed resin is discharged, the supply of the liquid A and the liquid B is stopped and the solenoid valve 7 is stopped.
3 is turned off, and the supply of air is also stopped. Then, when the injection port of the next molding die moves to a position facing the nozzle 3, the liquid A, the liquid B and the air are supplied again in the same manner, and the mixture 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 the conventional method of mixing and discharging without supplying air using the same apparatus, a molding failure occurs when molding is performed about 5 times or more continuously. Therefore, after continuous molding at the number of times or less, a step of stopping the supply of the liquid A, the liquid B and the air and supplying a cleaning solvent to perform cleaning.
However, according to the method of the present example, even when molding was continuously performed 25 times or more, no change was observed in the foam cells of the molded article during the molding, and the molding could be performed stably. Although the reason why the foam cells are stabilized is not clear, it is considered that the bubbles uniformly mixed in the resin become the core of foam cell formation during foaming.

At the end of the molding operation, supply of the liquid A, liquid B and air is stopped, and the solenoid valve 80 is turned off.
Is set to ON to supply the cleaning solvent to the mixing chamber 20, the end of the liquid A supply path 50, and the end of the liquid B supply path 60, and clean the inner walls and the surfaces of the stirring blades 41 to complete the operation. (Embodiment 2) The second embodiment shown in FIGS. 5 to 7 is one in which the present invention is applied to a high-pressure mixing apparatus. Portions having the same functions as in the first embodiment will be described with the same reference numerals as in the first embodiment.

The nozzle 3, the first hydraulic cylinder 11, and the 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 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 path 10 communicating with the nozzle hole 30.

In the resin supply path 10, an A liquid supply path 50 and a B liquid supply path 60 are opened so as to face each other, and a mixing chamber 20 is formed. An air supply passage 70 extending in the axial direction is formed at the center of the piston rod 14,
An air supply unit 7 similar to the first embodiment is connected to the end of the air supply path 70. The distal end of the air supply passage 70 opens at the distal end 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 this embodiment configured as described above, the solution A and the solution B are supplied to the solution A supply passage 50 and the solution B supply passage 60 at a high pressure of 150 kg / cm ² , respectively. When the nozzle 3 does not discharge, the piston rod 14 moves forward and closes the mixing chamber 20 as shown in FIG. At this time, the A liquid supply path 50 and the B liquid supply path 60
Open in notches 15 respectively, and
5, the A liquid circulation path 52 and the B liquid circulation path 62 communicate with each other. Therefore, the A liquid and the B liquid supplied from the A liquid supply path 50 and the B liquid supply path 60 are
5 flows into the A-liquid circulation path 52 and the B-liquid circulation path 62, and circulates in a closed circulation system.

At the time of discharge from the nozzle 3, when the piston rod 14 is retracted 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 respective openings face each other, the liquid A and the liquid B collide vigorously and are uniformly mixed. At this time, 0.5 mm 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 between the liquid A and the liquid B, and is mixed as fine bubbles in the mixed resin of the liquid A and the liquid B.

The mixed resin flows from the mixing chamber 20 to 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. Subsequently, the cleaning piston rod 13 advances, and the resin remaining in the nozzle hole 30 is discharged from the nozzle 3 to complete one process.

In the conventional high-pressure mixing apparatus, the variation of the foaming cells is caused by the fluctuation of the pressure of the liquid A and the liquid B. However, by supplying the air into the mixing chamber 20 as in the present embodiment, the cell becomes stable. A dense foam cell was obtained.

[0026]

According to the urethane foam resin mixing apparatus of the present invention, it is possible to produce a molded article having a stable foam cell even if the apparatus is continuously operated for a long time, thereby eliminating the need for a washing step in the middle. Productivity can be improved.

[Brief description of the drawings]

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

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

FIG. 3 is an enlarged sectional view of a main part of FIG. 1 viewed from the opposite side of FIG. 2;

FIG. 4 is an enlarged explanatory view of a main part of FIG. 1;

FIG. 5 is a sectional view of a main part of a urethane foam resin mixing apparatus according to a second embodiment of the present invention.

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

FIG. 7 is an enlarged sectional view taken along line LL of FIG. 5 during ejection.

[Explanation of symbols]

1: Base 2: Mixing section 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)

(57) [Claims] 1. A urethane foam which reacts with a mixing chamber, respectively.
It includes a plurality of liquid resin a plurality of resin supply path for supplying to the mixing chamber to form a down resin, and a gas supply channel for supplying gas to the mixing chamber, a plurality of the liquid in the mixing chamber A urethane foam resin mixing apparatus characterized in that the gas is supplied from the gas supply path into the mixing chamber and mixed together when the resins are mixed.