JPH10337521A - Method and device for spraying urethane stock solution in continuous urethane foaming step - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the quality, yield, distribution density and uniformity of sprayed urethane stock solution by spraying a hard polyurethane stock solution over a continuously moving face material and performing the foaming and curing process of the stock solution after causing an air current to directly act upon the stock solution. SOLUTION: A steel face material 13 is caused to travel by the lower face transport conveyor 3 of a continuous hard polyurethane foam manufacturing device 1' and then is heated up using a face material preheater 6. Next, an urethane stock solution 11 mixed by an air mixing process is spread from a mixing head 2. Thus the urethane stock solution 11 in which numerous bubbles are dispersed is conveyed spreading over the face material 13. In addition, an air current is caused to act vertically from an air nozzle 7 fixed about 90 mm distant from the surface of the lower face material 13 at a position away in the downstream of the mixing head 2. Consequently, the stock solution 11 is assisted to spread, then the bubbles 15 are broken to bring about such a state 12 that only the uniform bubbles generated by a chemical change are present. Thus the stock solution 11 undergoes the foaming and curing process through a double conveyor 5, and the irregularities-free and uniform quality foam can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface material reinforcing panel comprising a hard surface material and a hard polyurethane foam, or a urethane constituting a continuous production line for sandwich panels, which is used as a heat insulating panel for building materials, refrigerators and the like. The present invention relates to an improvement in a method for spraying a urethane stock solution in a continuous foaming step and a spraying apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, as a method for spraying a rigid polyurethane foam undiluted solution in a continuous production process of this kind of sandwich panel, as shown in FIG. 3, a face material preheating device 6 and a double conveyor 5 of a rigid polyurethane foam continuous production device 1 are used. A method is known in which the undiluted solution is sprayed on the lower surface material while the mixing head 2 is fixed in the upstream portion of the lower surface material or while the mixing head 2 is reciprocated in the width direction of the lower surface material 13 transferred on the lower surface material conveyor 3. I have.

As the mixing head 2 for spraying, (1) a low-pressure mechanical stirring type in which at least two kinds of stock solutions are mixed and sprayed by rotating blades in a stock solution stirring chamber, (2) A high-pressure stirring type in which each component is sprayed out while being mixed by being ejected and collided from the opposed discharge holes,
(3) An air mixing type or the like structure is used in which a gas such as compressed air is pressed into an undiluted solution stirring chamber, stirred, mixed, and sprayed.

[0004]

SUMMARY OF THE INVENTION A continuous hard polyurethane solution is sprayed on a moving lower surface material, foamed and cured, and joined to the upper surface material to form a heat insulating panel having a sandwich structure sandwiching the hard polyurethane foam. In the manufacturing process,
Although some differences are recognized depending on the above-mentioned stock solution mixing method, it is inevitable that some bubbles are mixed in the stock solution to be sprayed. Needless to say, the stock solution contains a foam element that foams the rigid polyurethane, but the bubbles in question here are not generated by the two-component chemical reaction and are contained inside the stock component solution. In any case, it is a peripheral gas that is physically mixed in the raw material solution when it is mixed in the raw material solution when mixing the raw material solution, or is caught between the raw material solution and the surface material when sprayed. This foam will be referred to in the present application by the expression "bubbles" to distinguish it from foams generated by the chemical reaction of the stock solution. As is clear from the above explanation,
Among the methods of mixing component liquids, in the case of the air mixing method (3), the gas injected into the undiluted solution is trapped inside, and the possibility of air bubble mixing is higher than in other methods. Get higher. However, even in the case of other component mixing systems, although the degree is smaller than that of the air mixing system, mixing of air bubbles is an unavoidable problem. Bubbles contained in the stock solution show various sizes on the sprinkled face material,
Approximately 30 mmφ, many of which are larger than the bubbles produced by the chemical reaction, and moreover easily float on the surface of the undiluted solution, so that when covered with the upper surface material, the foam formed inside the foam, especially with the upper surface material, It will remain as a void at the interface. As a result, a decrease in heat insulation performance, a decrease in mechanical properties such as compression and bending strength, and when the upper surface material is a film, paper, a steel plate, or the like, the voids appear as blisters on the surface,
It is a major cause of poor quality. For products that require high quality and require measures against voids,
This has been dealt with by a method of suppressing gas generation by high-pressure foaming. However, the high-pressure foaming method requires special equipment and management, and causes an increase in manufacturing cost. All of the above-mentioned stock solution mixing and stirring methods are widely used and widely used, and are cost-competitive. Among them, the air mixing method is simple in equipment and has a large tolerance for quality control, and is easy to handle. Although the cost advantage is larger than other methods, bubbles are apt to be mixed during mixing, and there is a strong tendency to cause the above-mentioned poor quality and reduced yield. To do
Despite significant technical and economic challenges,
Conventionally, a technique capable of solving this problem has not been developed.

Further, in a continuous manufacturing process for forming a heat insulating panel having a sandwich structure sandwiching a rigid polyurethane foam, a urethane stock solution sprayed on a lower surface material that proceeds is:
As the subsequent reaction progresses, the volume gradually expands and expands, covering the lower surface material and growing in the thickness direction at the same time,
This leads to the formation of a cubic urethane foam. However, the undiluted solution sprayed at one point on the lower surface material in a fixed, zigzag, or other pattern has a function of filling the space on the lower surface material left by the expansion effect due to foaming. However, the distribution density is not always uniform, and tends to have some variation. Therefore, it is a very important task to uniformly distribute the stock solution sprayed on the face material. Nevertheless, a technology that can solve this problem has not yet been developed. The present invention provides an extremely inexpensive method and apparatus that can be easily implemented with a completely new method of solving at least these two problems simultaneously and with simple equipment that can be attached to any conventional equipment.

[0006]

Means for Solving the Problems To solve the above problems, the present invention has the following constitution. (1) In a manufacturing process in which a hard polyurethane stock solution is sprayed from a mixing head onto a continuously moving face material and foamed and hardened to form a heat insulating panel, the stock solution sprayed on the face material is removed. A method for spraying a urethane stock solution, wherein an air stream is directly applied before the stock solution foams and hardens. (2) In the urethane undiluted solution spraying method of (1), the surface material is a lower surface material, and an upper surface material facing the lower surface material at a predetermined interval is moved at the same speed as the lower surface material. A method for spraying a urethane undiluted solution, wherein the air stream is directly applied to the undiluted solution sprayed on the lower surface material and then bonded to a foam top surface of the undiluted solution. (3) In the urethane liquid dispersion method according to (1) or (2), the air flow is blown out from a slit-shaped nozzle disposed at an upper position away from the lower surface material and extending over the entire width of the lower surface material. A uniform curtain-like air flow. (4) In the urethane foaming step of continuously producing a rigid polyurethane foam panel, at least one air nozzle that directly blows an air stream against the urethane stock solution sprayed on the panel material is sprayed with the hard polyurethane stock solution. A urethane stock solution dispersing device provided between the mixing head for use and the heating device for foaming and curing the stock solution of polyurethane, above the panel material conveying means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing the configuration of an apparatus for continuously producing a rigid polyurethane foam provided with an apparatus for performing the urethane stock solution spraying method of the present invention. That is, the present rigid polyurethane foam continuous production apparatus 1 ′
A mixing head 2, a lower surface material conveying conveyor 3, a double conveyor roll 4, a double conveyor 5, a surface material preheating device 6, and an air nozzle 7 for blowing an air stream from above the urethane stock solution 11 sprayed on the lower surface material; By arranging the face materials 13 and 14 on both surfaces of the urethane foam 12, it is possible to continuously produce a sandwich-shaped heat insulating material. The mixing head 2 includes pipes 8 and 9 for supplying two types of urethane stock solutions and an air supply port 10 for stirring the mixed solution.
It has.

An air-nozzle suitable for practicing the present invention comprises one or more commonly used nozzles, such as air guns, which blow medium to low pressure air through a small hole, above the face material. It is arranged in a line in the width direction at a distant position, or is arranged at a symmetrical position facing each other on the side of the face material, and the air flow is directly applied to the sprayed undiluted solution using the diffusion of the blown air flow. It is also an effective means of spraying the urethane stock solution.However, in order to uniformly apply the air flow to the stock solution spreading in a plane, a slit extending in the width direction of the face material is required. A uniform air flow is blown out of the nozzle in a curtain shape, and the air flow is applied evenly in the direction of travel of the surface material and in the width direction. It is preferable that the blowout has a length extending over the entire width of the lower surface material. Type nozzle with use slit preferred, which is also similar to the nozzle of the type for blowing air from the small holes, it is possible to use a commercially available nozzle. However, when it is not possible to spray in the form of a slit from the upper surface for some reason, such as a situation on the equipment, it is possible to cope with the air line from both sides. FIG.
A preferred example of the air nozzle 7 having a slit is shown in a sectional view. An air supply hole 17 is provided at one end face of a chamber 16 having a pentagonal cross section, and is connected to an air supply source (not shown).
The slits 18 are provided on the ridge lines of the two surfaces 19 and 20 at an interval of width d. In order to secure the accuracy of the slits, the slit forming plates 21 and 22 are screwed from outside the two surfaces 19 and 20 surrounding the slits. It is better to fix by appropriate means (not shown) such as the above, to suppress the variation in the interval and the depth of the slit d in the longitudinal direction, and at the same time to adjust it appropriately according to the conditions. Although there is no particular limitation on the material for manufacturing the chamber and the plate for forming the slit, aluminum, stainless steel, etc., which are widely used as structural members, are preferable materials. It may be subjected to an appropriate surface treatment such as alumite treatment, and it is suitable to use a stainless steel excellent in strength and durability for the slit forming plate. The wind speed of the airflow blown out of the slits is high in proportion to the pressure of the air supply source supplied to the chamber 16, and the air volume is mainly proportional to the slit area. Since the acting force of the airflow exerted is proportional to the product of the wind speed and the air volume, it is necessary to strictly control at least the two factors, that is, the supply pressure and the slit width, to obtain a uniform effect. As a result, the acting force is exerted evenly on the foaming surface of the urethane stock solution sprayed on the lower surface material with the passage of time, that is, in the advancing direction of the lower surface material and also in the width direction, thereby improving the product quality. Achieved. In the present invention, such a flow of air that is stable both temporally and spatially is referred to as a uniform flow of air, and an airflow in a range of a small wind in which the liquid level at the point of action slightly vibrates is applied. For the purpose of destroying air bubbles mixed in, the action force is slightly increased,
It is preferable to apply a slightly lower airflow to the diffusion. When the moving speed of the lower surface material on which the undiluted solution is placed is high, it is better to widen the slit width d and expand the working range of the air flow blown out from the air nozzle, but the air consumption also increases. In general, it is an effective method to adjust the range of action and the force of the air flow by changing the distance between the slit and the liquid surface, with the width being about 2 mm or less, more preferably about 0.1 to 0.5 mm. As important.

The installation position of the air nozzle is located between the mixing head 2 for spraying the hard polyurethane stock solution on the lower surface material and the double conveyor 5 for heating and processing the urethane stock solution to complete the foaming and curing. From the cream time at which the viscosity of the stock solution increases to the foaming area of about 2 to 5 times, a position where the air flow can directly act on the foaming top surface of the stock solution within the range where the stock solution retains fluidity. Should. However, strictly speaking, the position of the air nozzle should be slightly changed in accordance with the purpose of the air flow as described above, and the emphasis is placed on the purpose of destroying bubbles mixed in the urethane stock solution sprayed on the lower surface material. In this case, it is better to apply the airflow slightly before the undiluted solution spreads on the face material and spreads to the full width. At this stage, the liquid level height also rises, bubbles mixed in the stock solution rise to the surface, the viscosity of the stock solution increases, the film covering the bubbles loses fluidity, and it is easily broken by a slight external force, This is suitable as the timing of foam breaking. This region is located between the mixing head 2 and the double conveyor 5 for foaming and curing, and the space for installing the air-nozzle 7 is easily taken sufficiently. It is related to the composition of the stock solution, the reaction speed such as temperature, etc., and the moving speed and width of the lower surface material.
It can be said that about 0 to 800 mm is a preferable range. If the air nozzle is moved closer to the mixing head, the bubbles will be destroyed, but the foaming state of the undiluted solution surface may be disturbed.If the air nozzle is further away, the urethane will harden, and the air flow in the pressure range that does not disturb the liquid surface Bubble breakage becomes difficult.

In the case where the air nozzle is focused on the expansion of the urethane solution sprinkled on the lower surface material or the leveling of the liquid surface thickness, after the discharge with the high flowability of the stock solution, the air nozzle spreads in the width direction of the surface material. It is preferable to apply an air current in accordance with the above. In this case, a force to spread the undiluted solution is required, and it is better to slightly increase the blowing pressure of the airflow compared to the case of the above-described foam break, and to make the liquid surface act mildly, if it is in the standard condition range. The installation position is about 200 to 50 downstream of the discharge point.
A range of 0 mm is preferable, and after that, the urethane stock solution that has begun foaming is scattered, the thickness unevenness is increased, and when the urethane stock solution is brought closer to the mixing head, the flow of the solution that spontaneously foams and expands is hindered. In the case of, the quality tends to vary, which is not preferable.

It is needless to say that the vertical position of the air nozzle, that is, the distance from the lower surface material, is set at a height that does not contact the height of the liquid surface due to the foaming of the undiluted solution under operating conditions. Even if the production process is stopped for some reason and the urethane below the nozzle position completely foams on the lower surface material, the nozzle tip does not touch the liquid surface, and there is a sufficient height. A preferred installation position is the product thickness of the rigid polyurethane foam being manufactured plus 50 mm or less. However, as is well known, since the air flow blown out of the nozzle rapidly loses energy due to diffusion, a high nozzle position is not preferable in terms of energy saving, so the blowing position during operation is the distance of the product thickness of the heat insulating panel. The running cost can be reduced by providing a device that raises the nozzle position in synchronization with the emergency stop of the line and simultaneously shuts off the air supply to the nozzle. However, too close to the product thickness or less should be avoided because the air flow is poorly spread and the working range is narrowed.

The flow rate of the air blown out from the air nozzle should be selected according to the purpose in addition to the nozzle position described above. In any case, the air flow directly acts on the liquid material that has not yet solidified. The uniform airflow should be kept within a small breeze range that only slightly applies external force to the surface of the stock solution being foamed. For example, when breaking air bubbles mixed in the stock solution, the supply pressure of the air nozzle is 1.5 kgf / cm ² or less, preferably 1.0 kgf / cm ² or less.
/ Cm ² or less, particularly preferably in the range of 0.2 to 0.7 kgf / cm ² , and when the stock solution is spread on the face material, 1.0 kgf / cm ² or less, which is slightly lower than in the case of foam breaking, 0.7 kgf / cm ² or less, preferably 0.1 to 0.5 k
It is preferable to apply air in the range of gf / cm ² . Within these ranges, a slit-type air nozzle having low pressure resistance can be used without any problem.
As the air supply source, it is most convenient to supply 5 to 7 kgf / cm ² of high-pressure air supplied to ordinary factory piping via a suitable pressure reducing device. However, no matter which air supply source is used, the blown air flow directly acts on the joint surface with the upper surface material of the foamed polyurethane, so that oil, moisture and other impurities contained in the air supply are appropriately removed. Needless to say, it should be supplied to the nozzle after cleaning by means of clean air to make it clean air.The urethane surface during foaming is contaminated with impurities contained in the air current, and in extreme cases, abnormalities may occur in joining with the upper surface material. The occurrence of troubles that must come must be avoided.

In the present invention, the air nozzle blows the air stream directly from above or from the side away from the face material to the urethane stock solution on the face material. Generally, it is perpendicular to the lower surface material to be formed. However, the angle is not particularly limited, and a slight change may be made in connection with the purpose of the action of the blown airflow. In particular, the inclination of the face material in the advancing direction is preferable in order to promote the stretching effect of the stock solution. However, if the main purpose is to destroy bubbles mixed in the stock solution, it should be avoided if the inclination is too large because the effect of moving the foaming urethane stock solution on the lower surface material becomes stronger. Conversely, if the airflow is reduced,
It is preferable to incline the blowing angle in the upstream direction of the surface material, because the effect of promoting the spreading of the stock solution in the width direction is obtained.

In the present invention, the temperature of the air blown out from the air nozzle is an important control factor since it directly acts on the urethane stock solution sprayed on the lower surface material and has a subtle effect on the reaction speed of the stock solution. At the same time, it is possible to some extent to positively control the reaction rate by the air temperature. Under normal conditions, if the temperature of the blown air matches the factory environmental temperature range of 20 ± 5 ° C., the temperature effect of the blown air flow is hardly observed, and the standard foaming / curing reaction proceeds. When the air temperature is 5 to 10 ° C., the progress of the foaming speed is temporarily suppressed, the variation of the foaming speed in the width direction of the face material is suppressed, and the effect of leveling the quality is exhibited. Furthermore, although it is related to the humidity of the blown air when the temperature is lowered to 5 ° C. or less, a dew condensation film is generated on the surface of the urethane foam to inhibit the adhesion to the upper surface material and may cause unevenness in foaming. Absent. Regardless of the temperature of the blown air, as a general condition, it is necessary to remove the humidity in the blown air.As a common facility for removing impurities in the air, a dryer is installed on the air supply side. It is essential to provide. When the air temperature is raised to a high temperature of about 40 ° C., the apparent reaction is temporarily promoted. However, if the temperature is too high, the air-heating equipment becomes enormous, which not only increases the energy consumption but also increases the load on the indoor air conditioning.
Caution must be taken.

In the present invention, a sufficient effect can be obtained with one operation of the air blown out from the air nozzle. Therefore, the air nozzles may be arranged in a line in the width direction of the lower surface member. However, by arranging the nozzles in a plurality of rows, not limited to one time, and increasing the frequency of action, it is possible to suppress the action of each time mildly and to obtain a high-quality insulation product with less uneven foaming.

[0016]

EXAMPLE A steel plate face material (lower face material) 13 having a width of 600 mm was
Hard polyurethane foam continuous production apparatus 1 'shown in FIG.
To the lower surface material conveyor 3 at a line speed of 10 m /
min, and the temperature was raised to 40 ° C. by the face material preheating device 6,
When the urethane stock solution mixed by the air mixing method from the mixing head 2 is sprayed on the steel plate material 13 at a discharge rate of 10 kg / min, the urethane stock solution 11 containing a large number of bubbles 15 spreads on the steel plate material. proceed.
From the slit-shaped air nozzle 7 fixed at a height of 90 mm from the surface of the lower surface material at a position 500 mm away from the mixing head 2, a uniform air flow having a vertical flow was applied, and the width reached about 400 mm. The spread of the undiluted solution
Bubbles 15 which have been promoted by the air flow and which have floated on the liquid surface before reaching the same are destroyed by the action of the air flow by about 80 to 90%, and are generated in the stock solution by the chemical reaction of the constituent components. In this state, only fine and homogeneous foams are seen due to the foaming, and the liquid level height is almost evened. Then, heat treatment is performed with the double-sided conveyor 5 sandwiching the steel plate members on both sides, and the urethane stock solution is foamed and hardened to complete the heat insulating panel. Slit air
The slit width of the nozzle 7 is 0.3 mm, the length is 600 mm equal to the width of the steel plate face material, and the supply pressure is 0.5 kgf / cm ^2.
Met. When the air supply to the nozzle was stopped in an attempt, a large number of air bubbles mixed in the undiluted solution remained in the product without disappearing, and the unevenness of the steel plate covering both surfaces was remarkable, causing a quality problem. Level. In addition, the height of the nozzle is 60 mm
As the urethane undiluted solution had a tendency to be scattered when approached, it was necessary to slightly reduce the air supply pressure, and the nozzle surface could be buried in the undiluted solution during an emergency stop. Had to be changed from a fixed type to a lifting support type. However, by changing the nozzle to the lifting support type, the air consumption was reduced and the running cost was reduced.

[0017]

As described above, according to the urethane stock solution spraying method and apparatus of the present invention, bubbles of 2 to 30 mmφ mixed in the urethane stock solution sprayed on the face material are broken, and the flat face of the face material is broken. It has an excellent effect of preventing the occurrence of voids that impair the properties, eliminating partial variations in the heat insulation effect, improving product quality, and increasing product yield. In particular, among the mixing methods for spraying a urethane stock solution, the air-mixing method, which is most widely introduced at production sites, is simple because the equipment is simple, the quality control range is wide, the handling is easy, and the production cost is low. Compared with the high-pressure stirring method, when mixing heads are traversed, air bubbles are likely to be entrained.However, air nozzles are provided for both cases. The method according to the invention, in which an air stream is applied directly to a stock solution containing a large number of air bubbles sprayed on a face material, is almost completely solved and makes a great contribution to the development of production technology in the field.

Further, according to the urethane stock solution spraying method and apparatus of the present invention, the urethane stock solution sprayed on the moving face material can be actively spread on the face material and uniformly spread over the entire width. . In particular, a favorable effect was obtained by applying a gentle and uniform air flow to the low-viscosity stock solution immediately after being discharged from the mixing head. In particular, when the mixing head is fixed and the undiluted solution is scattered at only one point on the surface material, the diffusion effect is remarkable, but the mixing head traverses over the wide surface material and forms a zigzag undiluted solution. In the case of spraying, the action of the air flow evens out the sprinkling stock solution on the surface material, and in each case, the bubbles in the stock solution are destroyed and almost no voids are seen. A high-quality, high-grade insulating panel having an excellent urethane foam was obtained without a large increase in manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an apparatus for continuously producing a rigid polyurethane foam provided with a stock solution spraying method of the present invention.

FIG. 2 is a cross-sectional view of an air nozzle having a slit-shaped air blowing hole.

FIG. 3 is a schematic perspective view of a conventional general rigid polyurethane foam continuous production apparatus.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Conventional rigid polyurethane foam continuous production apparatus 1 ′ Hard polyurethane foam continuous production apparatus provided with stock solution spraying method of the present invention 2 Mixing head 3 Bottom material transport conveyor 4 Double conveyor roll 5 Double conveyor 6 Face material preheating device 7 Air nozzle 8, 9 Urethane stock solution supply pipe 10 Stock solution stirring air supply port 11 Urethane stock solution sprayed on lower surface material 12 Urethane stock solution that started foaming after spraying 13 Lower surface material 14 Upper surface material 15 Bubbles mixed in stock solution 16 Air nozzle chamber 17 Air nozzle air supply hole 18 Air nozzle air blowing slit 19, 20 Chamber wall 21 and 22 sandwiching air nozzle slit Plate forming air nozzle slit d Air nozzle slit width

Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 75:00 105: 04 B29L 9:00

Claims (4)

[Claims] 1. In a manufacturing process of spraying a hard polyurethane stock solution from a mixing head onto a continuously moving face material, and foaming and hardening to form a heat insulating panel, the stock solution sprayed on the face material. On the other hand, a method for spraying a urethane stock solution, wherein an air flow is directly applied before the stock solution foams and hardens. 2. The undiluted solution sprayed on the lower surface material, wherein the upper surface material facing the lower surface material at a predetermined distance is moved at the same speed as the lower surface material. 2. The urethane undiluted liquid spraying method according to claim 1, wherein the air stream is directly actuated and then bonded to the foam top surface of the undiluted liquid. 3. The air flow is a uniform curtain-shaped air flow which is blown out from a slit-shaped nozzle which is disposed at an upper position away from the lower surface material and extends over the entire width of the lower surface material. The urethane stock solution spraying method according to claim 1 or 2, wherein 4. In a urethane foaming step for continuously producing a rigid polyurethane foam panel, at least one air nozzle for directly blowing an air stream against a urethane stock solution sprayed on the panel material is provided with the hard polyurethane foam. A urethane stock solution spraying device provided between the stock solution spraying mixing head and the polyurethane stock solution foaming and curing heat treatment device and above the panel face material conveying means.