DE102013106364B4 - Process for producing a polyurethane block foam - Google Patents

Abstract

The invention relates to a method for producing a polyurethane block foam (12), wherein as starting materials (50) polyurethane waste (44), at least one dicarboxylic anhydride (56) or at least one dicarboxylic acid (58) or at least one dicarboxylic acid derivative (60) and at least a grafted reactant polyol (54) is provided, mixed and heated such that a dispersion polyol (26) is formed, after which the resulting dispersion polyol (26) is mixed with at least one system polyol (28) and then Isocyanate (34) is added to the mixture of dispersion polyol (26) and system polyol (28) such that a block foam (12) is formed, the starting materials (50) being contacted only with higher grade steels (62) become.

Description

The invention relates to a method for producing a polyurethane block foam.

Polyurethane slab foams are large-volume block foams which are produced by reaction of polyols with isocyanates. The particular property of the block foams is in particular their volume, since such foams are to be used for example for the production of mattresses.

When processing the polyurethane block foams accumulate polyurethane waste, which must be disposed of on the one hand and on the other hand lead to the fact that the effective amount of the actual recycled polyurethane foam blocks reduced.

Therefore, it is desirable to continue to use the polyurethane waste meaningful.

This can be done, for example, that the starting materials of the polyurethane are recovered from the polyurethane waste in order to reuse these for the production of polyurethane.

In DE 195 127 78 C1 a process for the recovery of polyols from polyurethane waste is described.

In particular, in the production of large-volume slab foams must be ensured, however, that the use of recycled starting materials in the polyurethane production in the same quality of the block foam as in the conventional production of polyurethane slab foam, d. H. without using recycled polyol.

The object of the invention is therefore to provide a process for the production of polyurethane slab foams in which polyurethane waste can be used and yet a same quality of the resulting slab foam can be achieved as in the conventional slabstock production.

This object is achieved by a method having the features of claim 1.

• a) Bereitstellen der folgenden Ausgangsstoffe:
• a1) Polyurethan-Abfalle;
• a2) wenigstens ein Dicarbonsäureanhydrid, wenigstens eine Dicarbonsäure und/oder wenigstens ein Dicarbonsäurederivat;
• a3) wenigstens ein gepfropftes Reaktand-Polyol;
• b) Vermischen und Erhitzen der Ausgangsstoffe derart, dass ein Dispersions-Polyol entsteht;
• c) Vermischen des Dispersions-Polyols mit wenigstens einem System-Polyol;
• d) Zugabe von Isocyanat zu der Mischung aus Dispersions-Polyol und System-Polyol derart, dass sich ein Blockschaumstoff bildet,

wobei die Ausgangsstoffe in den Schritten a) und b) nur mit korrosionsbeständigen Duplex-Stahl in Kontakt gebracht werden.The process according to the invention for producing a polyurethane block foam comprises the following steps:

• a) Provision of the following starting materials:
• a1) polyurethane waste;
• a2) at least one dicarboxylic acid anhydride, at least one dicarboxylic acid and / or at least one dicarboxylic acid derivative;
• a3) at least one grafted reactant polyol;
• b) mixing and heating the starting materials such that a dispersion polyol is formed;
• c) mixing the dispersion polyol with at least one system polyol;
• d) addition of isocyanate to the mixture of dispersion polyol and system polyol such that a block foam forms,

wherein the starting materials in steps a) and b) are brought into contact only with corrosion-resistant duplex steel.

Dicarboxylic anhydrides are preferably used or alternatively dicarboxylic acids or their derivatives which, usually at elevated temperature, can form dicarboxylic acid anhydrides with elimination of water.

It is further preferred if the reaction is carried out at reaction times of 1 to 10 hours and advantageously catalysts, in particular basic catalysts, more preferably in amounts of 0.1 to 5 wt .-%, based on the total reaction system used.

By mixing and heating the polyurethane waste with the grafted reactant polyol and at least one dicarboxylic acid anhydride and / or a dicarboxylic acid and / or a dicarboxylic acid derivative, the polyurethane waste is converted to a dispersion polyol, ie to a starting material for the production of polyurethane. By this reaction, all possible polyurethane waste, especially those incurred in the workup of the block foam, can be advantageously recycled, so that the disposal of waste can be omitted and a total of more block foam can be used effectively than in the non-utilization of polyurethane waste ,

To prepare the dispersion polyol, which is thus a recycled polyol made from polyurethane waste, the dispersion polyol is blended with a system polyol. The term "system polyol" is to be understood to mean that this is a polyol which has not been prepared by a recycling reaction in accordance with the reaction carried out in step b).

Subsequently, isocyanate is added to form by reaction of the polyols with the isocyanate, the polyurethane, wherein the release of CO ₂ at the same time foams the polyurethane to form the block foam.

When using dispersion polyols in mixture with system polyols, it has been found that the quality of the polyurethane block foam does not match that of the polyurethane block foam produced as standard. Because in the foam core arise in this manufacturing process using recycled or dispersion polyol brownish discoloration, which lead to rejects or missing parts and it also comes partially to the destruction of the foam by burning, which is known as scorching effect.

Surprisingly, it has been found that by using special contact materials, in particular in steps a) and b), the abovementioned effects which reduce the quality of the polyurethane block foam can advantageously be prevented.

Therefore, in the process in steps a) and b), the starting materials and all mixtures of the starting materials during the reaction are brought into contact with the dispersion polyol only with corrosion-resistant duplex steel.

Advantageously, the steps c) and d) can be carried out such that the dispersion polyol, the system polyol and the isocyanate preferably come into contact only with corrosion-resistant duplex steel.

Particularly preferably, the starting materials in steps a) and b), in particular a) to d), are brought into contact only with corrosion-resistant duplex steel 1.4462.

It has been found that when using duplex steel or steel 1.4462 discoloration and scorching effects in the production of polyurethane slab foams using recycled dispersion polyol can be advantageously avoided.

Preference is given to materials coming into contact with the starting materials, in particular containers, fittings and / or stirrers, which are formed and / or coated from corrosion-resistant duplex steel. Particularly preferred in step a3) is a reactant polyol having a molecular weight of 500-6000 g / mol and / or having a hydroxyl functionality of 2-5.

In step b), the starting materials are advantageously heated to a temperature of 120-270 ° C. before, after or during the mixing.

Preferably, the polyurethane waste is comminuted prior to step a) and mixed in step b) into a heated mixture of the grafted reactant polyol with at least one dicarboxylic acid anhydride and / or at least one dicarboxylic acid and / or at least one dicarboxylic acid derivative.

More preferably, in step c), 5-30% by weight of dispersion polyol is mixed with 70-95% by weight of system polyol on the total polyol mixture.

Advantageously, after step c), a step d) preparation of the block foam to produce polyurethane waste, in particular 5-20% polyurethane waste to the total block foam carried out, wherein the resulting polyurethane waste the polyurethane waste in step a1).

Preferably, steps a) to d) are carried out in situ.

Thus, it is advantageously possible to carry out the recycling reaction, ie the conversion of the waste of the already produced block foam in a plant with the production of the block foam, so that the starting materials for slabstock production can be preferably brought together immediately after recycling and preparation of the dispersion polyol.

Furthermore, the in-situ construction leads to the fact that waste from the block foam can advantageously continue to be used and recycled directly without delay by the manufacturer of the block foam, and the block foam production can be returned immediately.

A preferred embodiment of the invention will be explained in more detail with reference to the accompanying drawings, wherein

1 shows an apparatus for producing a polyurethane slabstock foam using dispersion polyol.

1 shows a device 10 for producing a polyurethane block foam 12 , The device 10 has a recycling container 14 , a system polyol container 16 and an isocyanate container 18 on.

The recycling container 14 and the system polyol container 16 are each with a first mixing head 20 connected. From the first mixing head 20 leads a line 22 to a second mixing head 24 with which also the isocyanate container 18 connected is.

In the recycling container 14 is, as described below, dispersion polyol 26 generated while in the system polyol container 16 System- polyol 28 is stored. Over the lines 22 becomes dispersion polyol 26 from the recycling container 14 to the first mixing head 20 supplied, wherein the amount of the supplied dispersion polyol 26 via a valve 30 can be regulated. At the same time, over the line 22 from the system polyol container 16 System polyol 28 to the first mixing head 20 passed, where also a valve 30 for controlling the amount of system polyol 28 leading to the first mixing head 20 is supplied, is available.

In the first mixing head 20 thus becomes a total polyol mixture 32 containing between 5-30% by weight of disperse polyol and 70-95% by weight of system polyol.

About the line 22 becomes the total polyol mixture 32 the second mixing head 24 fed, the amount of total polyol mixture 32 again over a valve 30 can be regulated. At the same time, the isocyanate container 18 isocyanate 34 to the second mixing head 24 supplied, whereby here too the amount of isocyanate 34 via a valve 30 can be regulated.

In the second mixing head 24 becomes the total polyol mixture 32 with the isocyanate 34 mixed and over a nozzle 36 on a conveyor belt 38 applied. By reaction of the isocyanate 34 with the total polyol mixture 32 polyurethane forms 40 with liberation of CO ₂ , by the release of CO ₂ to the polyurethane slabstock 12 about the transport time on the conveyor belt 38 foams.

The polyurethane block foam 12 is prepared, for example, by passing through appropriate cutting devices 42 is tailored.

This creates polyurethane waste 44 ,

This polyurethane waste 44 is in a crushing device 46 crushed and to the recycling container 14 fed, leaving the polyurethane waste 44 in the recycling container 14 the dispersion polyol 26 is recovered.

The recycling container 14 has a stirrer 48 on, the starting materials 50 for obtaining the dispersion polyol 26 needed to be mixed continuously. Next points the recycling container 14 a heating device 52 on, the starting materials 50 to one for the implementation of polyurethane waste 44 to dispersion polyol 26 required temperature can heat.

In the recycling container 14 is a template of a mixture of a grafted reactant polyol 54 and at least one dicarboxylic acid anhydride 56 or at least one dicarboxylic acid 58 or a dicarboxylic acid derivative 60 ,

This template is by the heater 52 to a temperature between 120 and 270 ° C, preferably 200 ° C, heated and by the stirrer 48 continuously stirred, with the crushed polyurethane waste 44 is added.

All devices of the device 10 during the implementation of polyurethane waste 44 with the starting materials 50 or the mixture of the starting materials 50 come into contact, are formed such that they are made either of higher quality steels 62 are formed or at least coatings of such higher quality steels 62 have, so that the starting materials 50 or their mixture during the reaction only with such higher-grade steels 62 get in touch.

That means at least the recycling bin 14 , the stirrer 48 and the line 22 coming from the recycling bin 14 to the first mixing head 20 leads, as well as the corresponding valve 30 made of high quality steel 62 is formed or has such a coating.

An example of such a higher quality steel is duplex steel 64 , especially steel 1.4462.

Also all other devices of the device 10 For example, the system polyol container 16 , the isocyanate container 18 , all other lines 22 , the mixing heads 20 . 24 and all the other valves 30 can from the higher quality steels 62 be formed.

Starting point for the recovery of secondary polyol of flexible polyurethane foam, in particular of foam waste, that is for the production of dispersion polyol 26 , is a method according to DE 195 127 78 C1 ,

However, it has been found to be useful in carrying out the process in conventional containers and reusing the dispersion polyol 26 for the production of polyurethane block foam 12 to core discoloration and material destruction due to spontaneous combustion of the polyurethane slabstock foam 12 can come.

It is therefore proposed to use only certain types of steel throughout the system, in particular duplex steel 64 ,

It has thus been shown that isocyanate-reactive dispersion polyols 26 , the after DE 195 127 78 C1 be made of steel or stainless steel reactors, for example steel 1.4571, and with isocyanates 34 converted into large-volume block foams, too strong core discoloration and scorching effects in the polyurethane block foam 12 to lead. In polyurethane flexible foam block production, for example, in the case of low-quality polyols, elevated temperatures can occur in the foam core which, in the presence of atmospheric oxygen, leads to brownish discolorations and thus to scrap and missing parts or even to the destruction of the polyurethane block foam 12 can result from burning. This effect, also known as scorching, should be largely avoided in the production of flexible block foam.

To avoid the scorching effect, very high quality requirements are therefore imposed on the starting raw materials and the polyols are added with antioxidants. The use of antioxidants reduces the risk of radical formation, as free radicals can intensify the scorching effect.

It has been found that with addition of even small amounts, about 5 to 10 wt .-% based on the total amount of polyol, of dispersion polyols 26 , the after DE 195 127 78 C1 have been produced, significant nuclear discoloration and scorching effects are detectable. The use of these dispersion polyols 26 is thus not possible in the production of voluminous polyurethane foams such as block foams in relevant quantities. The risk of producing low-quality foams with nuclear discoloration or the risk of fire is very high.

Surprisingly, it was found that the negative effects only occur when the dispersion polyols 26 be prepared on standard stirred tanks of normal steel or stainless steel such as steel 1.4301, steel 1.4401 or steel 1.4571.

Therefore, a process for producing a polyurethane slabstock foam will now be described 12 proposed in which for the preparation of the dispersion polyols 26 only medium-contacting materials are used, which are made of higher quality steels 62 are formed or coatings of such higher quality steels 62 exhibit.

Examples:

Example 1 (Comparative Example 1):

A dispersion polyol 26 is through implementation of polyurethane waste 44 with dicarboxylic acids 58 in the presence of grafted reactant polyols 54 at 200 C in a stirred reactor made of 1.038 steel. The final product has a hydroxyl value of 48 mg KOH / g and a viscosity of 4,560 mPas at 25 ° C.

One block foam with 1 m ³ volume is made up of 10 parts of dispersion polyol 26 . 90 Share system polyol 28 and 60 Share tolylene diisocyanate prepared.

At the core shows the polyurethane foam block 12 clear discoloration.

Example 2 (Comparative Example 2):

Analogously to the preparation in Comparative Example 1, the dispersion polyol 26 in a stainless steel stirred tank made of steel 1.4571. The produced dispersion polyol 26 has a hydroxyl number of 44 mg KOH / g and a viscosity of 5,230 mPas at 25 C.

A slabstock foam with 1 m ³ volume of 10 parts of the dispersion polyol 26 . 90 Share system polyol 28 and 60 Share tolylene diisocyanate prepared.

The block foam shows in the core on clear discoloration.

Example 3:

A dispersion polyol is prepared analogously to Comparative Examples 1 and 2 on a stirred tank, in which, however, all media contacting parts made of duplex steel 1.4462. The produced dispersion polyol 26 has a hydroxyl number of 46 mg KOH / g and a viscosity of 4,770 mPas at 25 ° C.

A first block foam of 1 m ³ volume is made up of 10 parts of dispersion polyol 26 . 90 Share system polyol 28 and 60 Share tolylene diisocyanate prepared.

Next, a second block foam with 1 m ³ volume of 20 parts of dispersion polyol 26 . 80 Share system polyol 28 and 60 Share tolylene diisocyanate prepared.

Next is a third block foam with 1 m ³ volume of 30 parts of dispersion polyol 26 . 70 Share system polyol 28 and 60 Share tolylene diisocyanate prepared.

All three block foams produced show no discoloration in the core even at higher dispersion polyol contents.

LIST OF REFERENCE NUMBERS

10

contraption

12

Polyurethane foam block

14

Recycling bins

16

System polyol container

18

Isocyanate container

20

first mixing head

22

management

24

second mixing head

26

Dispersion polyol

28

System polyol

30

Valve

32

Total polyol

34

isocyanate

36

jet

38

conveyor belt

40

polyurethane

42

cutter

44

Polyurethane waste

46

comminution device

48

stirrer

50

starting material

52

heater

54

grafted reactant polyol

56

dicarboxylic

58

dicarboxylic acid

60

dicarboxylic acid derivative

62

higher grade steel

64

Duplex steel

Claims (9)

Process for producing a polyurethane slabstock foam ( 12 ), comprising the steps of a) providing the following starting materials ( 50 ): a1) polyurethane waste ( 44 ); a2) at least one dicarboxylic acid anhydride ( 56 ), at least one dicarboxylic acid ( 58 ) and / or at least one dicarboxylic acid derivative ( 60 ); a3) at least one grafted reactant polyol ( 54 ); b) mixing and heating the starting materials ( 50 ) such that a dispersion polyol ( 26 ) arises; c) mixing the dispersion polyol ( 26 ) with at least one system polyol ( 28 ); d) addition of isocyanate ( 34 ) to the mixture of dispersion polyol ( 26 ) and system polyol ( 28 ) such that a block foam ( 12 ), characterized in that the starting materials ( 50 ) in steps a) and b) only with only corrosion-resistant duplex steel ( 64 ). Method according to one of claims 1, characterized in that the starting materials ( 50 ) in steps a) and b) are only brought into contact with corrosion-resistant duplex steel 1.4462. Method according to one of claims 1 or 2, characterized in that with the starting materials ( 50 ) coming into contact materials, in particular containers, fittings and / or stirrer ( 48 ), which are formed and / or coated from corrosion-resistant duplex steel. Method according to one of claims 1 to 3, characterized in that in step a3) a reactant polyol ( 54 ) having a molecular weight of 500-6000 g / mol and / or having a hydroxyl functionality of 2-5. Method according to one of claims 1 to 4, characterized in that in step b) the starting materials ( 50 ) are heated to a temperature of 120-270 ° C before, after or during mixing. Method according to one of claims 1 to 5, characterized in that the polyurethane waste ( 44 ) is comminuted before step a) and in step b) into a heated mixture of the grafted reactant polyol ( 54 ) with at least one dicarboxylic acid anhydride ( 56 ) and / or at least one dicarboxylic acid ( 58 ) and / or at least one dicarboxylic acid derivative ( 60 ) is mixed. Method according to one of claims 1 to 6, characterized in that in step c) 5-30 wt .-% of dispersion polyol ( 26 ) with 70-95% by weight of system polyol ( 28 ) is mixed on the total polyol mixture. Method according to one of claims 1 to 7, characterized in that after step c) a step d) preparation of the block foam ( 12 ) producing polyurethane waste ( 44 ), in particular 5-20% polyurethane waste ( 44 ) on the total block foam ( 12 ), wherein the resulting polyurethane waste ( 44 ) the polyurethane waste ( 44 ) in step a1). Method according to one of claims 1 to 8, characterized in that the steps a) to d) are carried out in situ.

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