JPS5821547B2 - Spraying method of foaming polyurethane stock solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for spraying a foaming polyurethane stock solution, and in particular, the foaming polyurethane stock solution is spread in a flocculent manner and the sprayed surface is relatively moved so that the spraying method is uniform over the entire surface. This relates to a method of spraying a undiluted solution to

Polyurethane foam is produced by mixing a component containing an active hydrogen compound having at least two active hydrogens and a component containing a polyisocyanate compound having at least two isocyanate groups, and then using this mixed foamable polyurethane stock solution. It is manufactured by foaming and curing by free foaming or foaming in a closed mold.

Normally, a foamable polyurethane stock solution starts foaming within a few tens of seconds at the latest immediately after the two components are mixed, and foaming is completed within a few minutes, and after a while after foaming is completed, the surface tackiness is lost and hardening occurs. Almost completed.

Since this reaction proceeds relatively quickly, it is difficult to process the foamable polyurethane stock solution before foaming and hardening, and this has not been done very often in the past.

When producing a laminate or sandwich board having a relatively thin polyurethane foam layer, it is difficult to uniformly disperse a foamable polyurethane stock solution two-dimensionally.

The active hydrogen compound-containing component and the polyisocyanate compound-containing component are mixed and the discharge port of the dispensing machine is dotted, so even if the foaming polyurethane stock solution is discharged onto a moving surface, the stock solution will not form in a line on the surface. It is only placed.

This method is used in the slab molding of ordinary flexible polyurethane foam using a moving conveyor, but this method is difficult because the viscosity of the foamable polyurethane stock solution is low and it is cast by its own weight on the conveyor, which also prevents foaming. This is because since foaming occurs three-dimensionally in the direction, the foaming stock solution expands to the required width, so there is little need for dispersion of the stock solution.

However, when using a highly viscous stock solution such as a foamable polyurethane stock solution for manufacturing rigid polyurethane foam, or when using a small amount of stock solution to form a thin polyurethane foam layer, the stock solution may not spread over the entire required surface. This method is inappropriate.

For this reason, a method of vibrating the discharge port in the width direction and arranging the stock solution in a zigzag manner on the surface has been considered, but although this is sufficient, problems such as surface appearance, foaming pressure, and filling properties remain.

That is, a colored foaming polyurethane stock solution: For example, the stock solution for rigid polyurethane foam is usually colored, and when a stock solution containing a colorant is used, the polyurethane foam is produced from the stock solution that moves over the surface while foaming. The color of the polyurethane surface is different from that of a polyurethane surface that has been foamed and cured without moving on the surface, resulting in color unevenness in appearance.

In addition, in the case of a sandwich board that has a polyurethane foam layer inside, where the polyurethane foam layer does not appear on the surface, in order to form a thin polyurethane foam layer, it is necessary to forcibly move the foaming stock solution over the surface. It is difficult to uniformly fill the entire surface of the sandwich board with polyurethane foam because the pressure must be lowered and it is difficult to spread the stock solution thinly and widely.

There is a spraying method for spraying the foaming polyurethane stock solution, but even if the stock solution is sprayed over a wide area, if the surface to be sprayed is wide, it will be relatively dotted, and it will cause the same problem as above. arise.

Furthermore, it is inevitable that overlapping portions will occur during dispersion, resulting in partially uneven thickness.

In addition, in the case of spray, if the stock solution is not mixed enough,
If the amount of sprayed stock solution per unit area of foil is not necessarily uniform, the spraying method may have operational difficulties (e.g., vaporization of the polyisocyanate compound, etc.), and this method is not necessarily sufficient.

Therefore, the preferred method is considered to be a method in which the foamable polyurethane stock solution is discharged from a linear discharge port, and the discharge port or the surface is moved relatively to arrange it two-dimensionally on the surface.

However, it is not only very difficult to spread the stock solution mixed in the mixer two-dimensionally and to discharge the stock solution at a uniform discharge amount from any position of the linear discharge port, but also to There is a disadvantage that a large amount of the stock solution remains and is lost, and that cleaning to remove the remaining stock solution cannot be easily performed.

The present inventor was forced to solve the above problems at the stage of conducting various research studies in order to establish a method for manufacturing a laminate in which a thin polyurethane foam layer is formed on a corrugated sheet such as slate.

Since the surface on which the polyurethane foam is to be formed is wavy, it is impossible to spread the foamable polyurethane stock solution uniformly with a doctor knife or the like.

In addition, by distributing the stock solution as uniformly as possible over the entire surface including the convex and concave portions of the wavy surface, the movement of the foaming stock solution in the lateral direction (parallel to the surface) is reduced, and the entire stock solution is evenly distributed. It is necessary to foam in the direction and harden it.

In order to solve this problem, the present inventor conducted various research studies on methods of spraying a foaming polyurethane stock solution.

As a result, the foamable polyurethane stock solution is once spread two-dimensionally on a surface (first surface) different from the surface on which the polyurethane foam is to be formed (second surface), and the foamable polyurethane solution on the first surface is It has been found that this problem of dispersion can be solved by pulverizing the foamable polyurethane concentrate and distributing it onto the second surface at a point when the concentrate is at least capable of further foaming.

In this case, the stock solution that is finely granulated from the first surface and sprayed on the second surface is spread linearly, so that by relatively moving the first surface and the second surface, The stock solution sprayed in a line can be applied two-dimensionally and uniformly onto the surface of the substrate.

This first surface is the surface of two rotating rolls placed in parallel with a certain gap.

The foamable polyurethane stock solution supplied onto this roll is spread over the roll surface by passing through the roll gap, and then is finely granulated by two brush rolls that rotate in contact with these two rolls, respectively. Spread on the surface.

The gist of the present invention is to provide a foamed product in which an active hydrogen compound-containing component having at least two active hydrogens and an incyanate compound-containing component having at least two incyanate groups are mixed. The foamable polyurethane raw material is supplied onto the surfaces of two rotating rolls placed in parallel with a certain gap between them, and then spread two-dimensionally on the surfaces of the rotating rolls through the gap, so that the foamable polyurethane stock solution is at least further When the foamable polyurethane stock solution is in a foamable state, the foamable polyurethane stock solution is pulverized by two brush rolls that are positioned approximately parallel to the two rotating rolls and rotate in contact with the rotating rolls, and then transferred to the second surface. A method for spraying a foamable polyurethane stock solution, characterized by spraying the foamable polyurethane stock solution.

The present invention will be explained in more detail by showing one specific example of the present invention.

FIG. 1 shows a side view of an apparatus for forming a rigid polyurethane foam layer on a corrugated asbestos slate sheet during spraying of a foamable polyurethane stock solution.

The active hydrogen compound-containing component and the polyisocyanate-containing component are mixed in a mixer (not shown), and the bundled foamable polyurethane stock solution is discharged from the discharge port 1.

A fixed amount of this stock solution is supplied onto the two rolls 2 and 3, and is spread two-dimensionally on the roll surface by the rotation of the rolls 2 and 3, and a foamable polyurethane stock solution layer 4 of a fixed thickness is formed.
It becomes 5.

At this point, the two brush rolls 6.7 are separated from the two rolls 2, 3;
does not come into contact with the foamable polyurethane layers 4 and 5.

The foamable polyurethane stock solution spread to a uniform thickness on the rolls 2 and 3 usually has already started foaming in many cases.

Therefore, it is preferable that the expanded foamable polyurethane stock solution is immediately transferred to the next step after it is uniformly spread on the roll to the required width.

That is, the brush roll 6.7 is brought into contact with the two rolls 2 and 3, and the brush roll 6.7 is rotated at a relatively high speed.

As a result, the foamable polyurethane stock solution on the roll is stripped off by the brush roll, pulverized into fine particles, and dispersed linearly.

The sprayed foamable polyurethane stock solution adheres and deposits on the slate corrugated plate 8, forming a foamable polyurethane stock solution layer 9.

By making the length of the roll 2.3 and the length of the brush roll 6.1 approximately equal to the width of the corrugated slate plate 8, the amount of the foaming polyurethane stock solution sprayed linearly by the brush roll can be adjusted to the width of the corrugated slate plate. The width of the corrugated slate or the above-mentioned spreading device is approximately equal to the width of the corrugated slate (
That is, by moving the foaming polyurethane stock solution in the longitudinal direction of the corrugated slate sheet, the foaming polyurethane stock solution is uniformly two-dimensionally spread over the corrugated slate sheet.

The amount of one time of spraying is adjusted by the amount of the foaming polyurethane stock solution supplied onto the two rolls 2 and 3, and the time of spraying is adjusted by the time of one rotation of the rolls (ie, the rotation speed).

Usually, the foaming polyurethane stock solution is sprayed over the entire surface of one corrugated slate plate in one spraying operation.

The foamable polyurethane stock solution layer 9 can be foamed and cured as it is, or it can be foamed and cured with a corrugated upper mold placed thereon to form a corrugated slate plate having a polyurethane foam layer on one side.

Moreover, a sandwich plate can be obtained by placing a corrugated slate plate or other plate body in place of the upper mold and foaming and hardening it.

In the apparatus shown in FIG. 1, the surfaces of the two rolls are the first surfaces, and the surfaces of the corrugated slate sheets are the second surfaces.

In order to form a uniform layer of foamable polyurethane stock solution over almost the entire surface of the roll, which is the first surface, it is preferable to discharge the stock solution while moving the stock solution discharge port 1 in the length direction of the roll. .

This spreads the stock solution over the entire surface of the roll within a short period of time.

Of course, even without moving the discharge port, the stock solution deposited between the two rolls can be spread uniformly over the roll surface by rotating the rolls several times.

In particular, since the volume of the stock solution increases as it foams, it is possible to spread the stock solution onto the rolls relatively easily by adjusting the gap between the two rolls.

When a foaming polyurethane stock solution is supplied to a roll and the stock solution is spread over the entire surface of the roll by rotation of the roll, a pool of the stock solution called a bank may occur between the two rolls.

The presence of this bank allows the stock solution to spread over the entire surface of the roll, but even after the stock solution has spread over the entire surface of the roll, this bank may remain.

In particular, as the stock solution foams, the volume of the stock solution increases, so the bank increases over time.

Therefore, when removing the undiluted solution from the roll surface with a brush roll, the undiluted solution remaining in this bank will not be sprayed in one rotation of the roll, so the undiluted solution in this bank will be removed by further rotation of the roll.

Therefore, the time required for spraying the stock solution increases, and it becomes necessary to adjust the moving speed of the corrugated slate plate.

Of course, the stock solution in the bank can be discarded, but this is not very economical.

Conversely, the presence of this bank can also be actively utilized to continuously spray the undiluted solution.

In other words, the rotating brush roll is constantly supplied with an amount of stock solution such that a bank always exists, even if not continuously from the discharge port, and preferably the bank has a length approximately equal to the width of the roll. By keeping it in contact with
The undiluted solution can be sprayed continuously.

Foaming starts from the moment the active hydrogen compound-containing component and the polyisocyanate compound-containing component are mixed to produce a foamable polyurethane stock solution, and the reaction in which the volume of the stock solution increases progresses relatively quickly. The time from spreading to spraying with a brush roll must be sufficiently controlled, and it is particularly preferable to keep temperature conditions, which are easily affected by the external atmosphere, constant.

Furthermore, when used in slab molding, etc., it is possible to perform continuous dispersion without forming the banks.

That is, the stock solution is continuously supplied onto two rotating rolls and passed between the two rolls to spread the stock solution, or if necessary, in addition, the discharge port is moved back and forth parallel to the rolls. Furthermore, the stock solution can be uniformly spread on the roll and continuously sprayed by a brush roll that rotates in constant contact with the roll.

In this method, since the supplied stock solution is quickly sprayed, the stock solution is less likely to change (for example, foaming begins) during spraying.

The brush roll must be rotated at relatively high speed.

This is to prevent the stock solution from remaining on the brush roll, and usually requires several thousand revolutions per minute.

Of course, the speed may be lower than this, as long as the undiluted solution does not remain on the brush roll.

With this brush roll, the stock solution is finely divided and sprayed,
This dispersion is performed linearly and uniformly over the entire length of the brush roll.

Of course, if the length of the roll is shorter than the length of the brush roll, or if there is no undiluted solution on the roll, the undiluted solution will not be sprayed.

In addition, if the stock solution on the roll is uneven in the length direction of the roll, the stock solution is sprayed onto the brush in an uneven amount in the length direction of the roll. Applications such as spraying a larger amount of stock solution from the central part of the direction than from other parts can be performed.

In this case, it is sufficient to increase the amount of the stock solution that adheres to the central portion in the longitudinal direction of the roll, and this can be done, for example, by reducing the diameter of the roll at the central portion.

The finely divided and dispersed foamable urethane stock solution adheres and deposits on the second surface, that is, in the case shown in FIG. 1, the slate corrugated plate.

This stock solution is not yet completely foamed and is still in a foamable state, so it has sufficient adhesion.

Therefore, by foaming and curing it directly on a corrugated slate plate, it can be firmly bonded.

The adhered fine particles of the stock solution foam and adhere to each other to form a polyurethane foam layer.

The point of time at which the foamable polyurethane stock solution is sprayed is not particularly limited as long as the stock solution can be further foamed.

However, in order to obtain sufficient adhesion on the second surface and to form a good quality foam layer by foaming, the time of spraying is preferably as early as possible from the time of formation of the foamable polyurethane stock solution.

This point is preferably when the volume of the stock solution undergoing foaming is approximately 5 times or less compared to the volume of the stock solution before the start of foaming.

Usually, when foaming is finally completed, the volume will be 20 to 30 times or more than the original solution.

Furthermore, the stock solution may already have started foaming at the time it is discharged from the discharge port, and this is a method usually called the 70 bath method.

On the other hand, a method of discharging the stock solution before foaming starts is called a non-frosting method, and both can be used in the present invention.

In the method of the present invention, the point of application usually needs to be earlier when using the floss method compared to when using the non-smooth method.

By the spraying method of the present invention, various polyurethane foam molded articles can be manufactured.

For example, the spraying method of the present invention can be used in place of the conventional molding method using a discharge port, such as by using a releasable sheet as the second surface and manufacturing a foam slab by so-called slab molding. can.

In particular, as mentioned above, it is advantageously used when spraying on hard plates such as corrugated slate plates and flat plates to produce plates with polyurethane foam on one side or sandwich plates with a polyurethane foam layer inside. Ru.

That is, since the present invention is characterized by a scale that uniformly spreads the stock solution over a wide area, it is preferably used in an application field where this feature can be exhibited.

The second surface, which is the surface on which the polyurethane foam is formed, is not particularly limited.

For example, the surface can be a flat surface with or without releasability as in the case of slab molding, as well as a non-planar surface such as the corrugated sheet shown in FIG. 1, or the surface of a three-dimensional object.

Further, this second surface may be peeled off after the polyurethane foam is formed, or may be left bonded to the second surface.

In particular, for example, as mentioned above, a laminate of a plate such as a flat plate or a corrugated plate and polyurethane foam, or a sandwich plate having a polyurethane foam layer in the middle, the second surface of which is bonded to the polyurethane foam. The application of the present invention is effective for manufacturing bodies.

Furthermore, in molding polyurethane foam, the present invention can be used to widely spread the stock solution within the mold when the mold is relatively large or when molding a thin polyurethane foam body.

It can also be used to manufacture various polyurethane foam products, such as the manufacture of laminate materials in which polyurethane foam is formed on flexible planar materials such as cloth.

Polyurethane foams produced using active hydrogen compounds and polyisocyanate compounds as basic components include flexible foams, rigid foams, semi-rigid foams, and others, and any of them can be used in the present invention.

Raw materials other than active hydrogen compounds and polyisocyanate compounds are usually used as raw materials for polyurethane foam, and these are used as a mixture of two components (either used premixed with one of the other or mixed simultaneously during the production of the concentrate). Ru.

These auxiliary raw materials include, for example, catalysts, blowing agents, foam stabilizers, crosslinking agents, fillers, colorants, flame retardants, stabilizers, and others.

The components normally used as essential components are catalysts (catalysts that promote the reaction between active hydrogen such as amines and metal compounds and incyanate groups, or the polymerization reaction of isocyanate compounds), blowing agents (water and fluorocarbons), and These include foaming agents (silicon compounds, etc.).

As active hydrogen compounds having two or more active hydrogen groups, polyether polyols, polyester polyols, polymer polyols, and other compounds having two or more, especially three or more hydroxyl groups are preferable, and as polyisocyanate compounds, two or more hydroxyl groups such as TDI and MDI are preferable. Aromatic compounds having more than one incyanate group are preferred.

These can also be used as bleed polymers by reacting the parts beforehand.

In the present invention, a foamable polyurethane stock solution is produced using these raw materials, but these raw materials are not particularly limited.

[Brief explanation of drawings]

FIG. 1 shows an example of a spraying method in which the method of the present invention is carried out, in which two rotating rolls 2, 3 and a foamable polyurethane stock solution 4, 5 are sprayed by a brush roll 6.1.

Claims (1)

[Claims] 1. A foaming polyurethane stock solution containing a mixture of an active hydrogen compound-containing component having at least two active hydrogens and a polyincyanate compound-containing component having at least two incyanate groups is mixed with a certain gap. The foamable polyurethane is supplied to the surfaces of two rotating rolls positioned in parallel, and then spread two-dimensionally on the surface of the rotating rolls through the gap, at the point when the foamable polyurethane stock solution is at least in a state where it can be further foamed. A foaming polyurethane stock solution characterized in that the stock solution is pulverized by two brush rolls that are positioned approximately parallel to the two rotating rolls and rotate in contact with the two rotating rolls, and then dispersed onto the second surface. Spraying method.