WO2002004190A1

WO2002004190A1 - Method and device for producing foams

Info

Publication number: WO2002004190A1
Application number: PCT/EP2001/007214
Authority: WO
Inventors: Hans-Michael Sulzbach; Ferdinand Althausen; Reiner Raffel; Martin Schamberg
Original assignee: Hennecke Gmbh
Priority date: 2000-07-07
Filing date: 2001-06-25
Publication date: 2002-01-17
Also published as: AU2001283887A1

Abstract

The invention relates to the production of foams from flowable reaction components which are loaded with a powder, fine-grained or fibrous loading material and with a foaming agent which is transformed from a liquid to a gaseous state as it passes a discharging mechanism (26) which is connected downstream of the (main) mixer (15). This discharging mechanism (26) is prevented from becoming clogged by an agglomerate reducer (18) which is situated between the loading material feed and the discharging mechanism (26) and which eliminates any agglomerates that have formed.

Description

Method and device for producing foams

The invention relates to a method and a device for producing foams from at least two reacting liquid reaction components, wherein at least one of these reaction components powdery, fibrous or fine-grained additives and at least one of these reaction components admixed with a blowing agent which changes from the liquid to the gaseous state in the event of a corresponding pressure jump become.

It is well known to produce foams, in particular from polyurethane, by reacting polyol with isocyanate.

The blowing agents for cell formation are those which are in a liquid state under the appropriate pressure, but which, when relaxed, change to a gaseous state as a result of a pressure jump of a corresponding height and are then available as cell gas when the reaction mixture is foamed. Carbon dioxide in particular has proven its worth in terms of environmental compatibility. A discharge device arranged behind the reaction mixer and designed accordingly serves to generate the pressure jump or the necessary relaxation. As such, sieves with a suitable mesh size, perforated plates, splitting elements, sintered metal plates, ball beds or the like are suitable, i.e. Organs which exert such a pressure jump on the propellant-laden reaction mixture as it flows through, through which the propellant changes from the liquid to the gaseous state. Such discharge organs have been launched on the market under the terms "Creamer" and "Lay-down device".

Such processes for the production of polyurethane foam are described in particular in EP-A 767 728, EP-A 777 564 and EP-A 794 857. At least one of the components (polyol, isocyanate) contains 2 to 6% by weight of CO ₂ dissolved at half the solution equilibrium pressure of typically 6 to 20 bar. This is then further mixed under pressure with the other component and expanded through a close-meshed sieve plate with several thousand passage openings of 0.1 to 0.3 mm in diameter to normal pressure, liquid foam having a bulk density of 50 to 120 kg / m ³ (without taking into account Fillers).

Usually, the density of the liquid foam is further reduced by water added to the polyol component, which forms CO2 on reaction with isocyanate.

It has been shown that these discharge organs, which cause a pressure jump, often become blocked when reaction components or reaction mixtures loaded with additives in powdery, fine-fiber or fine-grained form are processed. As a result, the discharge of the reaction mixture loaded with additive is inhomogeneous, and in particular when applied to a subordinate base, such as in the case of block foaming or in the production of panels, the application to the base takes place unevenly, which of course results in a block or panel which is inhomogeneous in cross section , Above all, the sieve plates become clogged. It was found that contents of agglomerates with a dimension of more than 10 μm in an amount of less than 0.1% based on total filler are prohibitive for a plant operation lasting several hours.

It is the task to protect the necessary relaxing discharge organ against blockages when processing reaction mixtures loaded with additives and a blowing agent.

This is achieved

a) that the additive and the blowing agent are added to and mixed with at least one of the reaction components,

b) the blowing agent being mixed in in the liquid state, c) that this reaction mixture loaded with blowing agent is discharged through a discharge member producing a pressure jump, the pressure jump being adjusted so that the liquid blowing agent changes into the gaseous state, and

d) that agglomerates formed from aggregate are comminuted before reaching the discharge member.

The invention preferably relates to the production of polyurethane foams from polyol and isocyanate, but is also for the production of others

Suitable for multi-component foams.

Fine-grained additives usually consist of melamine, activated carbon, chalk, calcium carbonate, heavy spar; powdery e.g. from graphite powder, ammonium polyphosphate or recycled powder; fibrous preferably made of glass, aramid or plastics, in particular polypropylene fibers.

Suitable powdered fillers typically have grain sizes of approximately 10 to 50 μm. Fibrous fillers preferably have a diameter of 6 to 14 μm and a length of 100 to 200 μm. It has been shown that such

Fillers, even after grinding and sieving, still have small proportions of coarse agglomerates or in the form of adhesively bound, newly formed agglomerates, which lead to the discharge organs being blocked with pressure release.

According to the invention, fillers are preferably used in an amount of 10 to 40% by weight, based on the finished foam, i.e. that the polyol filler dispersion has between about 20 and 50 wt .-% filler.

Although the way in which the additives are added to one of the reaction components is not directly related to the comminution of aggregate agglomerates which have formed, there are several alternatives which may be necessary in individual cases can offer advantages depending on the type of reaction component to be loaded or the additive. Such advantages can essentially only be determined empirically.

The fillers are preferably dispersed in the polyol component by means of conventional stirrers and dispersers with conveyance into or into the storage tank. The storage tank is preferably stirred to prevent the fillers from settling.

According to a first embodiment of the new method, the same reaction component serves as a carrier for the additive and blowing agent.

This has the advantage that the reaction component loaded with additive is diluted again by adding the liquid blowing agent.

Alternatively, one of the reactants with aggregate and another

Load the reaction component with a blowing agent.

A direct mutual interaction of aggregate and propellant thus only occurs when the two differently loaded reaction components are mixed with one another. Such a late intervention is without

This is important because the reaction mixture is discharged and foams immediately after mixing.

For example, one branch of a reactant additive and the other branch of blowing agent can also be mixed in, and then both loaded branches of the reactant are premixed with one another before they are mixed with the second reactant.

One branch of the reactant can also be loaded with aggregate and the other branch with blowing agent, but then the two are loaded Branches of the reaction component are fed separately to the second reaction component and mixed therewith.

With both variants, the addition of the additives and the blowing agent can be better controlled because they are not fed into the same component stream.

In addition to isocyanate, it is also possible to use two different polyols as further reaction components and to load one of them with the additive.

This is particularly advantageous if one of the polyols is sensitive.

While the addition of additive and / or blowing agent can be carried out online during production, it is preferred to generate a batch (storage tank) beforehand from the reaction component and additive.

According to the invention, the pre-dispersion presented or generated online in the storage tank is then subjected to agglomerate cleavage by means of high shear rates and, if necessary, impact forces.

According to the invention, the agglomerate clump rank takes place on-line during the supply of the dispersion to the main mixer and / or in the "conditioning mode" in a circulation line from the storage tank and back into it.

Preferably, the agglomerate clump is at least on-line, possibly additionally in the "conditioning mode".

The shear rates to which the pre-dispersion is subjected during the agglomerate cleavage are preferably more than 10 ⁵ s ^-1 .

Shear rates above 3'10 ⁵ s ^_1 are particularly preferred. The shear rate is generated by providing at least one perforated orifice in the feed line to the main mixer and / or the circulation line, through which the pre-dispersion under a high admission pressure of preferably 20 to 150 bar, particularly preferably 30 to 80 bar, more preferably 30 up to 50 bar.

Higher pressures are not harmless, even in the sense of agglomeration, but can only be achieved technically with great effort.

Shear rate in the sense of the invention is to be understood to mean 3 times the average passage speed of the dispersion divided by the radius of the pinhole.

The at least one pinhole preferably has a diameter of not less than 0.5 mm, preferably between 1 and 1.5 mm. With diameters above

2 mm at the preferred pressures, the high shear rates according to the invention cannot be achieved. With pinhole diameters below 0.5 mm there is a risk of clogging.

To ensure technical throughput rates, several perforated orifices are parallel, i.e. flowed through from the same form to be provided. For example, for a throughput of 100 1 / min polyol filler dispersion, it is advisable to use a perforated plate with 4 to 10 perforated screens with a diameter of 2 mm or with 10 to 25 perforated screens with a 1.5 mm diameter or with 25 to 50 perforated screens with 1 mm diameter.

If the type of filler used allows aperture diameters in the lower range according to the invention without the apertures becoming blocked, two or three perforated plates can be used one behind the other in the direction of flow, since the pressure required to achieve a sufficient shear rate is smaller with a smaller aperture diameter. According to a further preferred embodiment of the invention, two perforated screens are arranged opposite each other and flowed through in the opposite direction, so that the dispersion jets emerging from the perforated screens collide with one another. Such apparatuses are known in principle, for example, from EP-A 685 544 and WO 01/05517 for droplet dispersion in coating production.

The invention is explained below with reference to the accompanying figures. Show it:

1 shows an exemplary embodiment with feed of additive and blowing agent in the same reaction component,

2 shows an embodiment with feed of additive in one and of blowing agent in the other reaction component,

3 shows an exemplary embodiment with feed of additive in a first polyol component and feed of the blowing agent in a second polyol component and subsequent premixing of both polyols,

4 shows an exemplary embodiment analogous to FIG. 3 with the difference that both polyols open separately into the mixer,

5 shows the embodiment of the agglomerate crusher,

6 shows a further embodiment of the agglomerate crusher.

In Fig. 1, the device consists of a batch container 1, in which one

Storage container 2 via a line 4 provided with a pump 3 polyol and from a storage container 5 as an additive melamine via a with a metering

Snail 6 provided line 7 are introduced. The batch is created using a Agitator 8 generated. From the batch container 1, a line 9 opens, which leads via a metering pump 10, a shut-off valve 11, a filter 12, a mixer 13 and a pressure relief valve 14 into a main mixer 15 designed as an agitator mixer. A circuit line 16 branches off in front of the shutoff valve 11 and leads back into the batch container 1 via a shutoff valve 17 and an agglomerate shredder 18 according to the invention. A storage container 19 contains carbon dioxide as a blowing agent. A line 20 leads from it via a pump 21 and opens into the line 9 between the filter 12 and the mixer 13. A line 24 leads from a storage container 22 for isocyanate as the second reaction component via a metering pump 23 and opens into the main mixer 15 on. Inlets 25 for further additives are provided on the main mixer 15. The main mixer 15 is followed by an outlet element 26 which produces a jump in the propellant.

In Fig. 2, the device consists of a batch container 31, in which one

Storage containers 32 are introduced via a line 34 provided with a pump 33 polyol and from a storage container 35 as additive melamine via a line 37 provided with a metering screw 36. The batch is generated by means of an agitator 38. A line 39 opens from the batch container 31 and leads via a metering pump 40, an agglomerate chopper 41, a shut-off valve 42 and a filter 43 into a main mixer 44 designed as an agitator mixer. The agglomerate shredder 41 can be adapted to different additives by means of a drain indicator 57 and a control device 58. Between the agglomerate shredder 41 and the shut-off valve 42, a circuit line 46 containing a shut-off valve 45 branches off from the line 39 and which flows into the

Batch container 31 returns. A storage container 47 contains carbon dioxide as a blowing agent. A line 48 leads from it via a pump 49 and opens between a metering pump 50 and a mixer 51 into a line 52. This leads from a reservoir 53 for isocyanate and opens into the main mixer 44 via a throttle 54 arranged downstream of the mixer 51. Inlets 55 for further additives are provided on the main mixer 44. The main mixer 44 is one Subsequent pressure jump in the blowing agent generating outlet member 56. The pump 40 provides such a pressure that the dissolved carbon dioxide in the main mixer 44 does not change to the gaseous state and there is also a sufficiently large pressure difference above the agglomerate shredder for the agglomerate clump. Before the start of production, the device is preferably operated for a few hours in the "conditioning mode" with the valve 42 and the valve 45 open and in the "on-line mode" during production with the valve 42 open and the valve 45 closed.

In Fig. 3, the device consists of a batch container 61, in which one

Storage containers 62 are introduced via a line 64 provided with a pump 63, and a first polyol is introduced from a storage container 65 as an additive melamine via a line 67 provided with a dosing screw 66. The batch is generated by means of an agitator 68. A line 69 opens out from the batch container 61, said line 69 via a metering pump 70, a shut-off valve 71, a filter 72

Mixer 73 and a throttle 74 leads into a main mixer 75 designed as an agitator mixer. A circuit line 76 branches off before the shut-off valve 71, which leads back into the batch container 61 via a shut-off valve 77 and an agglomerate shredder 78. Carbon dioxide is contained as a blowing agent in a storage container 79. A line 80 leads from it via a pump 81 and merges with a line 82, which leads via a metering pump 83 from a reservoir 84 for a second polyol. The combined line 85 then leads via a mixer 86 and a throttle 87 between the filter 72 and the mixer 73 into the line 69. A line 90 leads from a reservoir 88 for isocyanate via a metering pump 89 and opens into the main mixer 75.

Inlets 91 for further additives are provided on it. A discharge element 92 is arranged downstream of the main mixer 75. Due to the choice of the flow cross-section of the discharge member 92, the drain jump is designed such that the propellant changes from the liquid state to the gaseous one. 4, the device consists of a batch container 101, into which a first polyol is introduced from a storage container 102 via a line 104 provided with a pump 103 and from a storage container 105 as an additive melamine via a line 107 provided with a metering screw 106. The batch is generated by means of an agitator 108. A line opens from the batch container 101

109, which leads via a metering pump 110, an agglomerate chopper 111, a shut-off valve 112 and a filter 113 into a main mixer 114 designed as an agitator mixer. The agglomerate shredder 111 can be adapted to different aggregates by means of a drain indicator 131 and a control device 132. Between agglomerate shredder 111 and shut-off valve

112 branches off from line 109, a circuit line 116 containing a shut-off valve 115, which leads back into the batch container 101. A storage container 117 contains carbon dioxide as a blowing agent. A line 118 leads from it via a pump 119 and merges with a line 120 to form a line 121. The line 120 leads via a dose umpe 122 from a storage container 123 for a second polyol. A mixer 124 and a throttle 125 are arranged in the combined line 121; it opens into the main mixer 114. In addition, a line 127 discharging from a reservoir 126 for isocyanate flows into this main mixer 114 via a metering pump 128. Inlets 129 for further additives are provided on the main mixer 114. It is followed by an outlet member 130 that produces a jump in the propellant. The jump in pressure is designed by the choice of the flow cross-section of the discharge member 130 such that the blowing agent changes from the liquid state to the gaseous one.

Fig. 5 shows an agglomerate shredder according to the invention, which consists of a transverse to

Direction of flow of the polyol filler dispersion arranged perforated plate 504 with (preferably sharp-edged) through holes 503, which is arranged in a pipe section 501, which may be expanded (502).

6 shows an agglomerate shredder designed as an installation 602 in a pipe section 601, in which the respective opposing (preferably sharp-edged) Holes are provided through which the polyol filler dispersion is pressed so that the dispersion jets emerging from opposite holes collide with one another.

Claims

Patentansprtiche

1. A process for the production of polyurethane foams from at least two reacting liquid reaction components, wherein at least one of these reaction components powdery, fibrous or fine-grained additives and at least one of these reaction components are mixed with a blowing agent which changes from a liquid to a gaseous state when there is a corresponding jump in

a) that the additive and / or the blowing agent are added to and mixed with at least one of the reaction components,

b) the blowing agent being mixed in in the liquid state,

c) this reaction mixture loaded with blowing agent is discharged through a discharge element (26, 56, 92, 130) which produces a jump jump, the jump jump being set such that the liquid blowing agent changes from the liquid to the gaseous state, and

d) that agglomerates formed from aggregate are comminuted before reaching the discharge member (26, 56, 92, 130).

2. The method according to claim 1, characterized in that the same reaction component serves as a carrier for additive and blowing agent.

3. The method according to claim 1, characterized in that one of the reaction components is loaded with additive and another of the reaction components with blowing agent.

4. The method according spoke 1 or 2, characterized in that one branch of the additive reactant and the other branch of propellant is admixed and that both loaded branches of the reactant are then brought together and, if necessary, premixed with one another before they are mixed with the second reactant.

5. The method according to claim 1 or 2, characterized in that one branch of the additive reaction component, the other branch of propellant is admixed and that the two loaded branches of the reaction component of the second reaction component are fed separately and mixed therewith.

6. The method according to any one of claims 1 to 5, characterized in that at least one of the loaded reaction components is conditioned by a circuit.

7. The method according to any one of claims 1 to 6, characterized in that the agglomerate cleavage takes place in that shear rates of above 10 ⁵ -s ^{-1 are} generated in the reaction component containing the filler.

8. Device for producing polyurethane foams from at least two reacting liquid reaction components, consisting of storage containers (2, 5, 19, 22; 32, 35, 47, 53; 62, 65, 79, 84, 88; 102,

105, 117, 123, 126) for flowable or meterable reaction components, additive and propellant as well as one with the storage containers (2, 5, 19, 22; 32, 35, 47, 53; 62, 65, 79, 84, 88 ; 102, 105, 117, 123, 126) connected and leading to a (main) mixer (15; 44; 75; 114) leading system, characterized in that a) that in at least one of one of the reaction component storage containers (2, 22; 32, 53; 62, 84, 88; 102, 123, 126) leading to the (main) mixer (15; 44; 75; 114) (9; 39; 69; 109) one supply line (7/9; 37/39; 67/69; 107/109) leading away from the aggregate storage container (5, 35, 65, 105) and one from the propellant

Open the storage tank (19; 47; 79; 117) of the discharge line (20/9; 48/52; 80/85/69; 118/121),

b) that the lines (9; 39, 52; 69, 85/69) for the loaded reaction components open into a (main) mixer (15; 44; 75; 114),

c) that the (main) mixer (15; 44; 75; 114) is followed by a discharge jump (26; 56; 92; 130) which produces a jump in the pressure, the pressure jump being set such that the blowing agent moves from the liquid into the gaseous state, and

d) that an agglomerate crusher (18; 41; 78; 111) is arranged between the mouth of the feed line (5; 35; 65; 105) for the aggregate and the discharge element (26; 56; 92; 130).

9. The device according spoke 8, characterized in that in the from one of the Reätionsenkomponent- reservoir (2; 62) to the (main) mixer (15; 75) leading line (4/9; 64/69) both the Lead (7; 67) for the aggregate and the lead (20; 80/85) for the blowing agent.

10. The device according to claim 8, characterized in that the feed line (37; 107) into the line (39; 109) leading from the first reaction component reservoir (32; 102) to the (main) mixer (44; 114). for the aggregate and into the second reaction component reservoir ter (53; 123) to the (main) mixer (44; 114) leading line (52; 120/121) open the supply line (47; 117) for the blowing agent.

11. The device according to claim 8, characterized in that the reaction component storage container (2; 32; 62; 102) of the reaction component to be loaded with filler is followed by a batch container (1; 31; 61; 101), from which a line (9 ; 39; 69; 109) leads to a (main) mixer (15; 44; 75; 114), and that from this line (9; 39; 69; 109) a circuit line (16; 46; 76; 116) leads back to the batch container (1; 31; 61; 101).

12. The apparatus according to claim 11, characterized in that the agglomerate shredder (18; 78) is arranged in the circuit line (16; 77).

13. Device according to one of claims 8 to 12, characterized in that the agglomerate shredder from at least one pinhole with a

Diameter from 0.5 to 2 mm.