DE4309228A1 - Process for the production of granules, extrudates, pellets and mouldings - Google Patents

Abstract

The invention relates to a process for the production of plastic extrudates, granules and, if desired, mouldings from (A) crosslinked isocyanate-based plastics, optionally mixed with (B) thermoplastics, where the isocyanate-based plastics (A) are polyurethane, polyurea and/or polyurethane-urea plastics, and where (A) and (B) are in a weight ratio of from 100 : 0 to 1 : 99, and where (A) has a mean functionality of >/= 2.5 in the soft segment, and whereby (A), without fillers, has a density of > 0.01, preferably from 0.01 to 1.0 g/cm<3>.

Description

The present invention relates to a novel method for producing Granules and molded parts in the cross-linked polyurethane plastics, possibly in Mixture with known thermoplastics and / or in a mixture with organic polyisocyanates, processed into molded parts.

The recycling of plastics has been very high in recent years Preserved importance. Also for cross-linked polyurethanes, such as z. B. in highly stressed bumpers are used, people have been looking for ways send them to material recycling. In this context are already Proposals have become known, according to which the use of materials is networked Polyurethane is proposed by so-called extrusion, z. B. in DE 37 33 756, DE 38 09 524, DE 38 02 427, DE 38 22 331, DE 40 30 282 and DE 40 39 020. This process was also applied to foamed polyurethane systems, possibly in Composite components with thermoplastics applied, cf. B. DE 40 19 800. As Binders can be organic polyisocyanates, solvents and Thermoplastics are used, see DE 38 40 167.

Although this work compared to the previously known prior art, the assumed that the thermosets could not be recycled, one great progress was the applicability of the methods described in limited in practice as much as for the production of large-area molded parts Large clamping forces that are usually not available (e.g. 10,000 tons Presses).  

The person skilled in the art also knows the possibility of very finely grinding and grinding polyurethanes this regrind as a filler of thermoplastic materials during their processing to incorporate. This method has a strong property deterioration of the thermoplastic molded article, so that this method is hardly used urgent problems of polyurethane recycling can contribute.

It has also already been proposed to use particularly fine powders places that are then in the formulations of polyurethane reaction systems as Allow fillers to be reinserted, see DE 42 00 443. As is currently the case the amount of filler in these formulations of polyurethane Reactive systems are limited to values in the range of approx. 20% because of the thus limited volume flows for the regrind material only production waste are processed. This path is therefore only feasible for polyurethane processors and can thus the amounts of waste material accruing in the near future, e.g. B. from the Do not include the automotive sector.

Other unpublished proposals are based on the knowledge that self cross-linked polyurethanes, possibly with the addition of thermoplastics over thermoplastic Have machines processed, see DE 41 02 999 and DE 41 20 693. In this There were special polyurethane-polyurea systems for the connection Use in reaction injection molding technology (RIM technology for manufacturing of molded polyurethane parts) that develop when reusing materials processed using thermoplastic machines; DE 42 24 164. These methods be sit with foamed polyurethane systems, especially those with very low Density, the disadvantage that it is in the filling area of the Thermoplastic processing machines to blockages and thus very low Throughput comes. Units for forced conveyance (stuffing screws) are Known expert in thermoplastic processing, the processing of such expensive foamed plastics, however, considerably. The use of powders is also in in this case associated with disadvantages in the feed.

A process for simple and inexpensive compacting is therefore required especially foamed plastics, preferably polyurethane-polyurea  Systems, possibly together with thermoplastics and / or organic Polyisocyanates.

It was therefore an object of the present invention, a new method and To provide device in which the disadvantages of the above described State of the art can be avoided and the state of the art beyond in advantageously, particularly in economic terms, is enriched.

Surprisingly, it has now been found that foamed, chemically crosslinked polyurethanes with densities above 0.01 g / cm ³ under the influence of shear forces and heat, optionally together with thermoplastic plastics and / or organic polyisocyanates, to form macroscopically homogeneous strands in a flatbed die press compacted. Following this strand production, it is also possible to produce granulate directly using a cutting device.

The following features are also associated with the method according to the invention:
All foamed polyurethanes can be compacted.

You can use any foamed polyurethane in any combination be compacted together.

All foamed polyurethanes can be in any form, if necessary even partially, non-positive connection with other materials be compacted together.

All foamed polyurethanes can be in any form of a mixture or Batches are compacted together.

The present invention thus relates to a process for the production of plastic strands, granules and, if appropriate, molded parts made from (A) crosslinked isocyanate-based plastics, optionally in a mixture with (B) thermoplastic plastics, characterized in that as isocyanate-based plastics (A ) Polyurethane, polyurea and / or polyurethane urea plastics are used, where (A) and (B) are in the weight ratio 100: 0 to 1:99, where (A) has an average functionality of 2.5 in the soft segment, where (A ) without fillers has a density of <0.01, preferably 0.01-1.0 g / cm ³ and wherein (A) has been produced from

• a) organic polyisocyanates,
• b1) Compounds with a molecular weight of 1800 to 12,000, which in statistical means at least 3 reactive towards isocyanate groups Have groups
• b2) optionally compounds with a molecular weight of 1800 to 12,000, which is a statistical average of at least 2 against isocyanate have reactive groups,

possibly

• c) polyamines with at least two primary and / or secondary, aromatic bound amino groups in the molecular weight range 108-400,

and if necessary

• d) optionally having ether groups (cyclo) alkane polypoles and / or (Cyclo) alkane polyamines in the molecular weight range 18 to 1799,

and possibly also with the use of

• e) auxiliaries and additives known per se from polyurethane chemistry,

in compliance with an isocyanate index of 60 to 140 in one or more stages drive has been produced.

The present invention also relates to those of the invention Processed compacted materials in the form of e.g. B. strands, Granules and molded articles.

The foams A) are produced by methods known per se Polyurethane chemistry from the starting materials mentioned below as examples.  

Suitable for the production of such plastics or foams Manufacturing methods are, for example, in the "Polyurethane" plastics manual, II edition, Carl-Hanser-Verlag Munich-Vienna (1983). The Starting materials can be used in one or more stages Be brought reaction, the implementation both in closed form as can also be done by free foaming of the starting materials. To the be preferred starting materials A) include the known foams with integral Density distribution, as it is known from the examples mentioned Starting materials can be obtained in closed forms.

Of course, here are the chemically cross-linked polyurethanes, Polyurethane ureas and polyureas produced by extrusion Materials can be used.

Suitable starting materials a) are any organic polyisocyanates, preferably however, aromatic polyisocyanates. For example, the in EP-B-00 81 701, column 3, line 30 to column 4, line 25 Links. Polyisocyanate is particularly preferred as component a) Mixtures of the diphenylmethane series used, as they are known in the art are accessible by phosgenation of aniline / formaldehyde condensates and the have a viscosity of 50 to 500 mPa · s at 23 ° C. Still special preferred as component a) are the polyisocyanate mixtures based on Toluene diisocyanate and the mixtures of both particularly preferred Polyisocyanate mixtures.

Component b) is a compound with isocyanate groups reactive groups in the molecular weight range 1800 to 12,000, preferably 3,000 to 70,000 or mixtures of such compounds, wherein component b) in the sense of the isocyanate addition reaction is over 2.2 has (medium) functionality. The average functionality of the is preferably Component b) at 2.2 to 3.0, in particular 2.5 to 3.0. Particularly good as Component b) are suitable connections, corresponding to these statements, Polyether polyols or mixtures of polyether polyols as in DE-AS 26 22 951, column 6, line 65 to column 7, line 47 are disclosed, also  According to the invention, preference is given to those polyether polyols whose hydroxyl groups at least 20%, preferably at least 40% of primary hydroxyl groups consist. The hydroxyl groups disclosed by way of example in DE-AS 26 22 951 containing polyester, polythioether, polyacetals, polycarbonates or polyester In principle, amides are suitable as component b) according to the invention, provided that they are the correspond to the above statements, but compared to the polyether polyols less preferred. Also those mentioned in DE-AS 26 22 951, by vinyl polymer modified polyether polyols or high molecular weight polyadducts or Polycondensates containing polyhydroxyl compounds, the above Descriptions regarding the functionality can advantageously be used as Components b) or as part of component b) are used.

The above statements are also suitable as the starting component b) corresponding polyetheramines or mixtures of polyetheramines, d. H. Polyether with groups which are reactive towards isocyanate groups and which at least become 10 equivalent%, preferably at least 20 equivalent% from primary and / or secondary, aromatic or aliphatic, preferably aromatic bound amino groups and the rest of primary and / or secondary, Compose aliphatic bound hydroxyl groups. Suitable such Aminopolyethers are, for example, those in EP-B-00 81 701, column 4, lines 26 to Column 5, line 40, compounds mentioned. The amino groups in these ver Bonds can also be derivatized in a suitable form, e.g. B. as ketimine groups.

Any component of course can also be used as component b) polyhydroxyl compounds exemplified with those exemplified Polyetheramines are used.

Component c), which may also be used, is aromatic polyamines of the in EP-B-00 81 701, column 5, line 58 to column 6, Line 34, of the type mentioned by way of example, wherein according to the invention also there as preferred diamines are preferred.

In those that may also be used as further structural components d) Polyols and / or polyamines are any non-aromatic  Compounds with at least two isocyanate reactive Groups in the molecular weight range 18 to 1799, preferably 18 and 62 to 500, in particular 18 and 62 to 409, are also suitable, for example polyhydric alcohols as described in EP-B-00 81 701, column 9, lines 32 to 50 are beard. Also suitable are, for example, those containing ether groups aliphatic polyamines, for example terminal primary amino groups polypropylene oxides of the stated molecular weight range. In Cyclo-aliphatic ring-containing polyols such as for example 1,4-di-hydroxycyclohexane or 1,4-bis-hydroxy-methyl-cyclohexane and polyamines such as 1,4-cyclohexanediamine, isophoronediamine, bis- (4- aminocyclohexyl) methane, bis- (3-methyl-4-aminocyclohexyl) methane. In consideration there is also water.

It is an essential point that in the production of the polyisocyanate poly addition products, component b) is used in such an amount, that the weight fraction of component b), based on the weight of the Components a) to d) at least 5% by weight, preferably at least 10% by weight is, the total proportion of components c) and (or d) is accordingly preferably below 20% by weight, in particular below 8% by weight, based on the Weight of component b). Often the polyisocyanate Polyaddition products A) around pure polyurethane foams, in their manufacture no compounds with amino groups reactive towards isocyanate groups can also be used.

If the polyisocyanate polyadducts A) are foams known blowing agents e), optionally used in addition to other auxiliaries and additives e). In Both chemical and physical blowing agents come into consideration inert gases dissolved in the starting components. Suitable blowing agents are examples as in EP-B-00 81 701, column 8, line 31 to line 51, or in that cited there "Plastic handbook" described in this way. The preferred blowing agent is water.

The preparation of the polyisocyanate polyadducts A) can also be found below Use of fillers and / or reinforcing materials e), which, if  in general, in amounts of up to 80% by weight, in particular from 20 to 60% by weight, based on the total weight of all starting components a) to e) can be.

Suitable fillers and / or reinforcing materials are, for example, barium sulfate, Kiselgur, sludge chalk, mica or in particular glass fibers, LC fibers, glass flakes, Glass balls, metal or carbon fibers. Very fine can also be advantageous Polymer powder, especially polyurethane powder made from ground soft or Rigid foam and PUR-RIM powder can be used.

Further auxiliaries and additives e) which may be used are examples the usual catalysts for the polyisocyanate polyaddition reactions, surface-active additives, cell regulators, pigments, dyes, flame retardants, Stabilizers, plasticizers or fungistatic or bacteriostatic Substances as described, for example, in EP-B-00 81 701, column 6, lines 40 to Column 9, line 31 are described by way of example.

Component B) is a thermoplastic, for example polyolefins such as polypropylene or polyethylene, copolymers of propylene with other olefinically unsaturated monomers, impact modified Polyolefins such as mixtures of polypropylene and ethylene / propylene / diene copolymers, polyacrylates such as polymethyl methacrylates, Polystyrenes, styrene / acrylonitrile copolymers, polycarbonates, linear, thermo plastic polyurethanes, polyesters such as polyethylene or polybutylene terephthalate, Vinyl chloride polymers and copolymers such as polyvinyl chloride or PVC-ABS Polymers. Polypropylene, copolymers of propylene are preferred other olefinically unsaturated monomers, linear thermoplastic polyurethanes, plasticized polyvinyl chloride or PVC / ABS blend used.

The use is also possible, but less preferred in the present case of polyimides, polysulfones, polyetherfulphones, aromatic polyarylates, poly benthiazoles, aliphatic and / or aromatic polyamides, polyether ketones, Polyphenyl sulfides.  

Component B) can consist of individual plastics of this type or also any physical mixtures, for example as heterogeneous or homogeneous Polymer system, in the form of blends or polymer alloys reach.

Component B) can also contain auxiliaries and additives, in particular fillers and Reinforcing materials of the type mentioned in amounts of up to 80% by weight contain the weight of component B).

The process is preferred on a flat developed for animal feed die press performed; such machines are for example at FA. Bald- Mechanical engineering, Reinbeck, FRG, available. Several run on these machines small rollers around on a horizontal perforated disc; the drive of the Rolling is done by a central shaft. There is also the option of small rollers over sprockets on the die level and sprockets on the To drive the axes of the small rollers via the central shaft, so that the Roll the rollers under friction with the perforated disc on the perforated disc. For the Compacting it is essential that the ratio of hole diameter and Hole length of a hole in the flat die has a value of 7.5, preferably 9 exceeds.

The small rollers shear the material to be processed together with the Flat die and then press it through the holes, this is the material condensed. It is sheared on the walls of the hole and the thereby generated friction of the material against each other and on the bore walls the temperature increase of the material necessary for the process. This The temperature can be increased in a simple manner via the thickness of the flat die or about the diameter and the exact shape of the holes in the flat die can be set.

The flat die should have a certain thickness so that it can withstand the pressure of the Press rolls can withstand; of course, there should also be a certain minimum thickness therefore be exceeded so that the material in the holes the pressed Material opposes so much resistance that it condenses and that the to the  Walls created friction material for compaction and compacting sufficiently plasticized. It is important to ensure that the procedural Heating the materials the decomposition temperatures of the materials, e.g. B. from 190 ° C for flexible PUR foam and 200 ° C for PUR-RIM materials, not above steps.

Of course, the flat die can also be tempered separately.

The exact mode of operation of this machine in the machine market is exemplary Würzburg 32 (1989) page 2 ff and 37 (1989) page 4 ff.

The products according to the invention have a high bulk density of approximately 0.5 to 0.7 g / cm ³ , are free-flowing and are therefore well suited for economical logistics.

The compacted material produced in this way in the form of pellets or granules is suitable as the starting material for a wide variety of recycling techniques:

• - Pellets made of flexible polyurethane foam can use conventional thermoplastic processing and can be processed relatively easily and blind in the process.
• - Polyurethanes are in this form of granules in chemolytic processes such. B. glycolysis, aminolysis and hydrolysis can be used advantageously.
  The pellet form is also advantageous for extrusion.
• - The polymer pellets produced in this way can be used for thermal treatment processes ren can be used advantageously.

Examples example 1 Production: component a)

60 parts by weight of a trifunctional polyether, molecular weight 6000, produced by adding a total of 87% PO and 13% EO to TMP,
40 parts by weight of a filled polyether, molecular weight 6000, produced by blockwise addition of 68.75% PO, 14.58% EO and 16.66% TDI-hydrazine polyaddition product on TMP,
3.8 parts by weight of water,
0.05 part by weight of catalyst 1
0.25 part by weight of catalyst 2
0.45 part by weight of catalyst 3
0.4 parts by weight crosslinker diethanolamine
1.0 part by weight of a stabilizer based on polysiloxane-polyether block copolymer
are mixed together and stirred until homogeneous.

Production: component b)

TDI 80/20 and PMDI are mixed homogeneously in a ratio of 70:30.

Production of polyisocyanate polyaddition product A)

105.95 parts by weight of component a) with 48.5 parts by weight of the compo nente b) and 5 s with a laboratory stirrer (diameter of the stirrer blade approx. 5 cm) homogenized at 4200 rpm. Immediately after that the reaction Mix in a preheated to 55 ° C with a wax-based release agent separate, given form and the form closed. After 10 minutes of mold life the foamed polyisocyanate polyaddition product is removed from the mold.  

The demolded molded article is available on a commercially available cutting mill e.g. B. from Pallmann, D-6660 Zweibrücken, model PS-4-5, in about 6 mm Squat pre-shredded and then placed in the flat die press. The flat die press, manufacturer Kahl, Reinbek, model 14-175 was with a die 30 mm thick. The die had 200 holes with a diameter of 3 mm. The flat die press was operated at a speed of 100 rpm.

The foamed polyisocyanate polyaddition product was compressed into compact strands that left the press at a temperature of 160 ° C. These strands were granulated and gave a material in granular form with a bulk density of 0.66 g / cm ³ .

Example 2

Control panel material, consisting of a commercially available, black colored cover PVC / ABS film (component B), a Bayfill backfill foam (compo nente A) and a carrier made of talc-filled, isotactic PP (Stamylan P 53 T 1030 from DSM, also component B), mixing ratio 55 parts by weight of PP, 30 parts by weight of Bayfill and 15 parts by weight of PVC / ABS, was first in hand plate sawn large pieces.

These pieces were cut in a Pallmann cutting knife mill, D-6660 Zwei bridges, model PS-4-5, pre-shredded to a granulate with a 3 mm sieve insert then placed in the flat die press. The flat die press, manufacturer Kahl, Reinbek, model 14-175 was equipped with a die with a thickness of 30 mm. The die had 200 holes with a diameter of 3 mm. The flat die press was operated at a speed of 100 rpm.

The pre-shredded polyisocyanate polyaddition product was compressed together with the thermoplastics PVC / ABS and PP into compact strands that left the press at a temperature of 180 ° C. These strands were granulated and gave a material in granular form with a density of 1.15 g / cm ³ .

Claims (13)

1. A process for the production of plastic strands, granules and, if appropriate, molded parts made from (A) crosslinked plastics based on isocyanate, optionally in a mixture with (B) thermoplastic, characterized in that the plastics based on isocyanate (A) are polyurethane - Polyurea and / or polyurethane-urea plastics are used, (A) and (B) in a weight ratio of 100: 0 to 1:99, where (A) in the soft segment has an average functionality of 2.5, where (A) without fillers has a density of <0.01, preferably 0.01 to 1.0 g / cm ³ and wherein (A) has been produced from

• a) organic polyisocyanates,
• b1) Compounds with a molecular weight of 1800 to 12,000, which have a statistical average of at least 3 groups capable of reacting with isocyanate groups,
• b2) optionally compounds with a molecular weight of 1800 to 12000, which on average have at least 2 groups reactive towards isocyanate groups,

possibly

• c) polyamines with at least two primary and / or secondary, aromatically bound amino groups in the molecular weight range 108-400

and if necessary

• d) optionally having ether groups (cyclo) alkane polyols and / or (cyclo) alkane polyamines of the molecular weight range 18 to 1799,

and possibly also with the use of

• e) the auxiliaries and additives known per se from polyurethane chemistry,

while maintaining an isocyanate index of 60 to 140 in one or more step process has been produced. 2. The method according to claim 1, characterized in that the production of Plastic strands, granules or pellets in a flat die press is made in the revolving rolling the material through a hole press washer, and the ratio of bore length to bore diameter of the drilled holes of the perforated disk a value of 7.5, preferably out of 9. 3. The method according to claim 1 or 2, characterized in that the Her position of the plastic strands, the granules or the pellets at Tempera structures in the range from 100 ° C to 240 ° C, preferably at temperatures in the range from 130 ° C to 190 ° C and particularly preferably at temperatures in the range from 145 ° C to 180 ° C. 4. The method according to any one of claims 1 to 3, characterized in that the Production of the plastic strands, the granules or the pellets with dwell times of the material in the holes of the pelleting machine in the range of 0.1 seconds to 10 minutes, preferably in the range of 0.5 seconds to 60 seconds and particularly preferably in the range from 1 second to 30 seconds is made. 5. The method according to any one of claims 1 to 4, characterized in that (A) is a rigid polyurethane foam. 6. The method according to any one of claims 1 to 4, characterized in that (A) is a flexible polyurethane foam. 7. The method according to any one of claims 1 to 4, characterized in that (A) is an integral polyurethane foam.   8. The method according to any one of claims 1 to 7, characterized in that as thermoplastics B) polypropylene, copolymers of propylene with other olefinically unsaturated monomers, linear thermoplastic Polyurethane, plasticized polyvinyl chloride or PVC / ABS blends be used. 9. The method according to any one of claims 1 to 8, characterized in that at processing 100 parts of the mixtures of A) and B) 0 to 80 parts Fillers and reinforcing materials C) can also be used.