DE4324156A1 - Process for the preparation of hydroxyl-containing compounds from (polyurethane) polyurea wastes - Google Patents

Description

The invention relates to a process for the preparation of polyisocyanate Polyadditionsverfahren suitable hydroxyl-containing compounds Polyurethane and / or polyurethane polyurea wastes by Alkoholytische Zerset tion of these plastics and subsequent further reaction of Alkoholyseprodukte to reduce their content of low molecular weight, sterically unhindered, aromatic amines.

The alcoholic decomposition of the polyisocyanate polyaddition process produced plastics is known in principle. However, the problem is the alcoholic decomposition of polyurethane or polyurethane polyurea wastes with recovery of useful Alkoholyseprodukten, in particular the Problem of working up of such plastics using poly isocyanate mixtures of the diphenylmethane series and aromatic diamines as chains had been made, d. H. of urea group-rich PUR waste, unresolved.

Glycolates of urea group-containing or -rich polyurethane or poly Urethanpolyharnstoffabfällen are characterized by a relatively high content low molecular weight, primary, aromatic amines, in particular to steric unhindered, primary, aromatic amines (B. Naber: "Recycling of Polyurethanes (PUR) ", plastics recycling conference of the TU Berlin, 01.10.1991).  

This impairs the reusability of such glycolysates in the isocyanate Polyadditionsprozess under certain circumstances considerably. For one thing, it has a high content low molecular weight, primary, aromatic amines due to their high reactivity a negative impact on the processability of such glycolates z. In the Reaction injection molding (RIM). This manifests itself z. B. too short flow paths, d. H. Sophisticated shapes can not be filled.

On the other hand, too high a content of low molecular weight, primary, aromatic Amines, in particular to sterically unhindered, primary, aromatic amines to cause such a disturbed polymer structure that low intrinsic products schaffsniveau be obtained (high glass transition temperature, low tensile strength and tear strain).

It was therefore the object underlying the invention, a new method for Preparation of hydroxyl-containing compounds of polyurethane poly urea or polyurea wastes by alcoholic decomposition available to provide, free of low molecular weight, sterically unhindered, primary, aroma Amines or at least in their content are greatly reduced.

This object has been achieved with the provision of the following Procedure to be solved:

The present invention is therefore a process for the preparation of hydroxyl groups suitable for the polyisocyanate polyaddition process send compounds of polyurethane and / or polyurethane polyurea wastes, characterized in that

• I. in a first stage with polyurethane and / or polyurethane polyurea wastes low molecular weight di- and / or polyols and optionally higher molecular weight Polyols are reacted at temperatures of 160 to 260 ° C, wherein preferably during the heating phase which is located in the reaction vessel Water (for example, registered by wet starting materials) removed by distillation will, and  
• II. In a second stage, the amine-containing alcoholysis products obtained in the first stage either
  • A) at temperatures of 50 to 1 80 ° C, but below the alcoholysis temperature of the first stage, further reacted with stirring, or
  • B) are reacted with dialkyl dicarbonates and / or 1,3-dicarbonyl compounds.

The first stage alcoholysis reaction can be carried out by methods known per se respectively:

1. Alcoholysis with macroglycols

Coarsely ground or finely crushed polyurethane or polyurethane poly urea waste (preferably after dehydration of the mixture in Temperature range from 60 to 220 ° C) at temperatures of 160 to 240 ° C, with Macroglycols in weight ratio waste: macroglycol equal to 2: 1 to 1: 100, preferably 1: 1 to 1: 20 reacted. Preferred macroglycols are the Macroglycols known from PU chemistry from the classes of polyethers, Polyesters, polylactones and 350 molecular weight range polycarbonates to 4000, preferably 500 to 2000 with functionalities 2 in question.

2. Alcoholysis with low molecular weight di- and / or polyols

Coarsely ground or finely crushed polyurethane or polyurethane poly Urea waste (preferably after dehydration) at temperatures of 160 to 260 ° C with low molecular weight di- and / or polyols in weight ratio of waste to low molecular weight di- and / or polyol of 10: 1 to 1:10, preferably 5: 1 to 1: 3, reacted.

As low molecular weight di- and / or polyols come z. For example, ethylene glycol, diethy glycol and higher condensates, 1,2-propylene glycol, dipropylene glycol and higher condensates, hexanediol, glycerol, trimethylolpropane, and their Ethoxylation and / or propoxylation products with molecular weights <350 in question.  

Optionally, the di- and / or polyols used in excess in the Connection to the alcoholytic decomposition reaction partly by distillation from the hydroxyl-containing decomposition products are removed.

Optionally, the alcoholysis products also before, during or after the alcoholic decomposition reaction for viscosity adjustment Makrogly molecular weight <500, as found in polyurethane chemistry are known per se, are added.

According to the above-described Alkoholyseverfahren hydroxyl groups are enthal tende compounds that still significant amounts of free, sterically unge contain aromatic amines, so that their use in the polyisocyanate-poly addition process is considerably limited or impossible.

Surprisingly, it has now been found that the content of interfering amines according to variant A) of the second stage of the process according to the invention so far can be reduced that valuable products are obtained, which is out records for reuse as a reactant for polyisocyanates in Polyisocyanate polyaddition process are suitable.

Variant A) of the second stage of the process according to the invention comes without Use of additional reactants. It is that the alcoholysis product the first stage at a temperature below the Alkoholysetemperatur over a Period of 2 to 24 hours is further stirred. It seems to be running Rearrangement reactions through which disturbing, free, sterically unhindered, aromatic amines are at least so sterically blocked that they are in use in the polyisocyanate polyaddition process, the polyaddition products no longer nega tively influence.

The necessary post-reaction time (stirring time) depends on the plastic used waste and alcohol used for alcoholysis. She can through the night reaction temperature are affected. The post-reaction temperature should preferably wise between 60 and 160 ° C lie. Preferably, a post-reaction temperature which is at least 20, more preferably at least 50 ° C below the Alcohol temperature is maintained.  

According to variant B) of the second stage of the process according to the invention takes place the further reaction of the alcoholysis product from the first stage by reaction of dialkyl dicarbonates or 1,3-dicarbonyl compounds.

Compared to variant A) there is the advantage of variant B) in the lower required derliche reaction temperature and the generally homogeneous product.

The reaction of dialkyl dicarbonates with amines is known per se (eg. W. Thoma u. H. Genth, Medicine and Chemistry 7, 793-801 (1963), Verlag Chemie, Weinheim a. Mountain road).

The reaction of 1,3-dicarbonyl compounds, especially acetoacetic esters derivatives with amines is known per se (H. Glaser in Houben-Weyl: Methods of Organic Chemistry, 11/1, Stuttgart (1957)).

However, the literature is no indication that this reaction to Reduction of the content of primary, aromatic amines in alcoholysis products of polyurethaneurea or polyurea wastes used to advantage so that the resulting products are excellent for reuse in the Polyisocyanatpolyadditionsprozeß are suitable.

The reaction of the amine-containing Alkoholyseprodukte with dialkyldicarbonates takes place advantageous at temperatures of 0 to 100 ° C, preferably below 60 ° C. The Amounts of dialkyl dicarbonate are calculated so that a equivalent Ver ratio of dialkyl dicarbonate to amino groups of 1: 3 to 5: 1, preferably 1: 1 to 2: 1, results.

Optionally, inert solvents such as cyclic polyethers, such as. Tetra hydrofuran or dioxane, dialkyl carbonates such as. B. diethyl or dimethyl carbonate or cyclic carbonates such as. For example, ethylene or propylene carbonate for dilution be used. Particularly advantageous solvents are ethanol or Methanol used. When using a solvent of the above It will generally be necessary to reuse these before reusing Hydroxyl-containing compounds in Isocyanatpolyadditionsprozeß de to remove by distillation.  

As dialkyl dicarbonates are compounds of the formula

in question
wherein R represents a linear or branched, saturated hydrocarbon radical having 1 to 18 carbon atoms, preferably R = CH ₃ , C ₂ H ₅ .

The reaction of the amine-containing Alkoholyseprodukte with 1,3-Dicarbonylverbin Applications advantageously at temperatures of 40 to 160 ° C, preferably from 60 to 140 ° C. The amounts of 1,3-dicarbonyl compounds are calculated so that an equivalent ratio of 1,3-dicarbonyl compound to amino groups of 1: 3 to 5: 1, preferably 1: 1 to 2: 1 results.

To complete the reaction or to accelerate the reaction is the With the use of a catalyst advantageous. Protons are used as catalysts acids such. As chloroacetic acid, Trichloressigsäue, trifluoroacetic acid, p-Toluolsul fonic acid, methanesulfonic acid, sulfuric acid or phosphoric acid and their condenses sate or cationic acids such. As boron trifluoride, tin dichloride, iron (III) chloride u.ä. in Question. The catalysts are usually used in amounts of from 0.001 to 10% by weight, preferably 0.01 to 2 wt .-%, used.

To complete the reaction, it may also be advantageous in the Reaction formed water from the reaction mixture, for example by distillation remove.

As 1,3-dicarbonyl compounds come z. B. 1,3-diketones such as pentane-2,4-dione, Dimedone, or β-ketocarboxylic acid derivatives such. B. the esterification of the Acetoacetic acid with mono-, di- or polyols such as methanol, ethanol, propanol, Butanol, ethanediol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, glycerin, tri methylolpropane, trimethylolethane or pentaerythritol in question. Especially preferred are the esterification products of acetoacetic acid with mono- and diols.

In the following examples, which serve to illustrate the invention will be the following starting materials or alcoholysis products are used:

Where:

OH-Z Hydroxyl number [mg KOH / g] NH-Z Amine number [mg KOH / g] S-Z Acid number [mg KOH / g]

Polyurethane urea A1

It is a granulate of a max. Grain size of 8 mm glass fiber reinforced polyurethaneurea density of 1.26 g / cm ³ , prepared in analogy to Example 2 of DE-PS 26 22 951.

glycolyzate GI

In a 20-liter planschlifftopf equipped with a stirrer and heating jacket 2.4 kg Submitted diethylene glycol, overlaid with nitrogen and preheated to 220 ° C. In the hot glycol are added portionwise to 12 kg of A1 under nitrogen blanketing carry. The addition is such that there is always a stirrable mixture. After a reaction time of about 9 hours, a liquid product is obtained with the following data:

OH-Z 180 mg KOH / g NH-Z 82 mg KOH / g S-Z 0.04 mg KOH / g

sterically hindered, primary, aromatic diamine: 3.78% by weight sterically unhindered, primary, aromatic diamine: 3.80% by weight

glycolyzate GII

In a equipped with stirrer and heating jacket 20-l planschlifftopf be 8 kg Submitted dipropylene glycol and 4 kg of A1 and blanketed with nitrogen. The mixture is stirred for 2 h at 200 ° C. Subsequently, with 4 kg of a polyether polyol (Desmophen® 3973, BAYER AG: OH-Z = 28). In conclusion, under  reduced pressure distilled off 7 kg of dipropylene glycol. A liquid is obtained Product with the following data:

OH-Z 172 mg KOH / g NH-Z 45 mg KOH / g S-Z 0.03 mg KOH / g

sterically hindered, primary, aromatic diamine: 1.41% by weight sterically unhindered, primary, aromatic diamine: 1.66% by weight

1,4-butanediol acetoacetate Comp. I

In a 1-liter four-necked flask with distillation bridge 650 g of acetoacetic acid ethyl ester and 225 g of 1,4-butanediol stirred at 140 ° C. After 8 h at 140 ° C are 225 g Ethanol distilled over. A thin liquid colorless liquid is obtained.  

Example 1

In a 20-l planschlifftopf with stirrer and heating mantle are 12.4 kg GII and 1290 g of 1,4-Butandioldiacetoacetat submitted. It gives 0.05 wt .-% methanesulfone acid and stirred for 24 h at 90 ° C. This gives a liquid at room temperature Product with the following data:

OH-Z 158 mg KOH / g NH-Z 37 mg KOH / g S-Z 0.27 mg KOH / g

primary, sterically hindered, aromatic diamine: 0.75% by weight primary, sterically unhindered, aromatic diamine: 0.16% by weight

example 2

In a 20-liter planschlifftopf with stirrer and heating jacket 13.2 kg GI and 3.065 kg of 1,4-butanediol diacetoacetate submitted. It gives 0.05 wt .-% methanesulfone acid and stirred for 12 h at 95 ° C. This gives a liquid at room temperature Pro with the following data:

OH-Z 162 mg KOH / g NH-Z 74 mg KOH / g S-Z 0.35 mg KOH / g

primary, sterically hindered, aromatic diamine: 0.45% by weight primary, sterically unhindered, aromatic diamine: 0.16% by weight

example 3

In a 20-liter planschlifftopf with stirrer and heating mantle 14.5 kg GII and Submitted 2.55 kg of ethyl acetoacetate. 0.02% by weight of methanesulfone is added acid and stirred for 12 h at 90 to 100 ° C. There will be another 0.9 kg of acetoacetic acid acid ethyl ester added and stirred for a further 6 h at 90 ° C and a slight vacuum. This gives a liquid product at room temperature with the following data:

OH-Z 160 mg KOH / g NH-Z 59 mg KOH / g S-Z 0.31 mg KOH / g

primary, sterically hindered, aromatic diamine: 0.15% by weight primary, sterically unhindered, aromatic diamine: <0.1% by weight

example 4

In a 3.6 l flat-bottomed pot with stirrer and heating jacket 2.5 kg GI at 30 ° C. submitted and 490 g of dimethyl dicarbonate added dropwise within 90 min. To Another 90 min. And distilling off methanol to obtain a viscous product with the following data:

OH-Z 155 mg KOH / g NH-Z 12 mg KOH / g S-Z 0.06 mg KOH / g

sterically hindered, primary, aromatic diamine: 0.17% by weight sterically unhindered, primary, aromatic diamine: <0.03 wt%

example 5

In a 20-liter planschlifftopf with stirrer and heating mantle 16 kg GII at 140 ° C. covered with nitrogen and stirred. The content of free, steric unhindered, aromatic diamine is in each case after the in the following Table indicated time by HPLC analysis as follows:

post-reaction Diamine content 0 hours 1.66% by weight 1 hour 1.59% by weight 2 hours 1.50% by weight 4 hours 1.39% by weight 6 hours 1.23% by weight 8 hours 1.04% by weight 10 hours 0.93% by weight 12 hours 0.77% by weight 14 hours 0.64% by weight 16 hours 0.50% by weight 20 hours 0.36% by weight

example 6

820 kg of dipropylene glycol and 400 kg of A1 are introduced into a 1300 l boiler. The mixture is heated to about 140 ° C. and distilled at 100 mbar over a period of about 30 min. 15 kg of a mixture consisting of water and dipropylene glycol (water content is depending on the degree of moisture of Al and is about 30 to 40 wt .-%), from.

The mixture is overlaid with nitrogen and stirred at 210 ° C for about 4 hrs. Then 640 kg of dipropylene glycol are distilled off (150 ° C, 10 mbar). After cooling to 100 ° C is diluted by addition of 340 kg of a polyether polyol (Desmophen® 3973, Bayer AG; OH-Z = 28) and receives a liquid product with the following data:

OHN 180 mg KOH / g HLD 30 mg KOH / g S-Z 0.02 mg KOH / g

sterically hindered, primary, aromatic diamine: 0.5% by weight sterically unhindered, primary, aromatic diamine: 0.55% by weight

Claims (10)

1. A process for the preparation of suitable for the polyisocyanate polyaddition process suitable, hydroxyl-containing compounds of polyurethane poly urea and / or polyurea wastes, characterized in that

• In a first stage polyurethane and / or polyurethane polyurea waste with low molecular weight di- and / or polyols and optionally higher molecular weight polyols at temperatures of 160 to 260 ° C are reacted and
• II. In a second stage, the amine-containing alcoholysis products obtained in the first stage either
  • A) at temperatures of 50 to 180 ° C, but below the Alko-curing temperature of the first stage, further reacted with stirring who the, or
  • B) with dialkyl dicarbonates and / or 1,3-dicarbonyl compounds to be set.

2. The method according to claim 1, characterized in that in the second stage A) is stirred for a period of 2 to 24 hours. 3. The method according to claim 1 or 2, characterized in that the Temperature in the second stage A) is 120 to 160 ° C. 4. The method according to claim 1, characterized in that in the second stage B) per equivalent of amine 0.3 to 5 equivalents of dialkyl dicarbonate and / or 1.3- Dicarbonyl compounds are used. 5. The method according to claim 1 or 4, characterized in that the Um tion in the second stage with dialkyl dicarbonates at 0 to 100 ° C, preferably at 20 to 70 ° C, is performed.   6. The method according to any one of claims 1, 4 or 5, characterized in that the second stage reaction with dimethyl and / or diethyl dicarbonate he follows. 7. The method according to claim 1 or 4, characterized in that the Umset in the second stage with 1,3-dicarbonyl compounds at one temperature from 40 to 160 ° C, preferably 60 to 140 ° C, takes place. 8. The method according to any one of claims 1, 4 or 7, characterized in that the second stage reaction with 1,3-dicarbonyl compounds in Presence of catalytically effective amounts of protonic acids takes place. 9. The method according to any one of claims 1, 4, 7 or 8, characterized in that are used as 1,3-dicarbonyl esterification products of acetoacetic acid with C ₁ -C ₆ mono- and / or diols. 10. Use of according to one of claims 1 to 9 prepared Hydroxyl-containing compounds for the Polyisocyanatpoly addition process.