KR100307689B1 - Process for the powdering of polyurethane, polycarbamide and / or polyurethane-polycarbamide materials in rolling mills - Google Patents

Abstract

Free fall out of the roll slit 4 when two or more rollers 2,3 powder the polyurethane polycarbamide and / or polyurethane-polycarbamide material in a roller mill rotating at different circumferential speeds. A very economical operation method is achieved by conveying the coarse fraction to the roll slit 4 and separating and releasing the particulate matter adhered to the roller 3 having a higher circumferential speed from the coarse fraction.

Description

Process for powdering polyurethane, polycarbamide and / or polyurethane-polycarbamide materials in rolling mills

In the present invention, in a roller mill in which two or more rollers rotate at different circumferential speeds, the material to be milled is fed into a roll slit formed by the roller, after which it is separated into a coarse fraction and a particulate fraction, the coarse fraction being a roll slit. And the particulate fraction is sent to the next process, which relates to a process for powdering polyurethane, polycarbamide and / or polyurethane-polycarbamide materials.

In recent years, the reexamination of plastics has become a very important position. Example

Uh, the possibility of material recycling of crosslinked polyurethane used in high stress automotive bumpers is being investigated. In general recycling, in order to reuse these waste materials in powder form, in particular as filler, it is necessary to powder, in particular mill. Particularly fine powdering is required to use them as fillers in compositions for polyurethane reaction systems. The use of roller mills is known (Patent Publication 42 07 972-A1). Milling produces a mixture of a large amount of coarse particles and a small amount of fine particles. The coarse particles are picked up and conveyed to the gap between the rollers. This sorting method is very uneconomical since the screening results in a large amount of very large particles and a relatively small amount of particulates.

The object of the present invention is to make the already known methods more economical. This object is achieved by collecting and conveying freely falling coarse particles downstream of the roll slit and separating the particulate fraction present in the sheet adhered to the roller with a higher circumferential speed by separating it from the coarse fraction.

According to the known method, both rollers were scraped with a scraper to supply all the milled material to the screen. On the contrary, according to the present invention, the sheet made of the particulate fraction, formed by the roller which rotates faster during the powdering of the material, can be released and used separately without being sent to the free-falling assembly and fraction.

Of course, the sheet also contains some coarse fraction, but preferably the particle diameter spectrum is shifted towards the particulate end.

For many possibilities of recycling, the particulate fraction can be reused directly. However, especially when fine powder is required, it is preferable that the sheet composed of the fine particle fraction is further classified into coarse particles and fine particles. Known screening methods can be used for this purpose. When sorting in the processing step the particulate fraction is larger, even larger than the coarse fraction. If there is a possibility of reusing immediately, including a relatively small amount of coarse particles as above, they are released, otherwise they can be returned to the roll slit for remilling.

It can be seen that the sheet can be removed and fed to another roll slit.

One particularly advantageous method consists in feeding the sheet bonded to the roller by the roller directly to the roll slit formed between the roller and the third roller.

However, since the third roller must be arranged in an upwardly rotating manner, the coarse fraction here cannot be separated by free fall as in the first roll slit. As such, if the coarse fraction has to be separated once again after passing through the second roll slit, the sorting process must be performed.

Preferably. The coarse fraction to be recycled is cooled.

There is considerable friction during the milling process and therefore heat is generated. Since some of the particles in the coarse fraction pass through the roll slit several times, the milled material will become hot if not cooled and therefore damaged.

Starting materials for carrying out the process are preferably polyurethane flexible foams, polyurethane structural foams or RIM materials made of polyurethane, polyurethane-polycarbamide or polycarbamide. These materials are characterized by a particularly high tendency to form sheets during milling. However, powders of these materials are particularly suitable for recycling.

The powders produced by the novel process can be fed to conventional thermoplastic processes and processed relatively easily and can be mixed with thermoplastics. Extremely finely powdered polyurethanes can be used, for example, in glycolysis, It can be advantageously used for chemical decomposition processes such as decomposition and hydrolysis. The powder form is also advantageous for extrusion. This is especially true when using lacquered RIM structures as starting materials. Polyurethanes can be used as fillers in polyurethane reaction mixtures to be reprocessed only in very fine powder form. Powders prepared according to the invention can also be used advantageously in thermal processing techniques.

The production of the polyurethane, polycarbamide and / or polyurethane-polycarbamide materials from which the powder is obtained for recycling as a result takes place by methods known per se in polyurethane chemistry. These are insoluble and therefore thermoset materials. The chemical compositions from which the materials are obtained and how they are processed to obtain articles (bumpers, dashboards, side-aprons, spoilers, spoilers, etc., furniture, household articles, etc.) for the automotive industry, are in particular described. Kunststoff-Handbuch, Polyurethane, 2nd ed., Carl Hawser Verlag, Munich / Vienna (1983).

The drawings schematically illustrate several modified methods using the drawings of the relevant milling units, the methods are described in more detail below:

When carrying out the process according to the drawing shown in FIG. 1, the waste material pre-crushed to an appropriate size is transferred to the roll slit 4 formed between the two rollers 2, 3 via a feed hopper 1. To reach. The rollers 2 and 3 have the same diameter: but the roller 3 rotates at a higher circumferential speed. A sheet of finer particles 5 is formed on the roller 3, while the coarse fraction is collected in the collecting hopper. It falls freely to 6 and is conveyed to the feed hopper 1 by the conveyor 7, for example, a braking chain. The sheet 5 is separated from the roller 3 by the scraper 8 and is conveyed to the sorting device 10 through the chute 7. The roller 2 is also removed by the scraper 11, and these are also conveyed through the chute 12 to the sorting device 10. The sorted coarse fraction is conveyed to the feed hopper 1 via the conveyor 13, while the particulate fraction is removed via the outlet 14 and fed to a temporary storage facility or sent directly to a further process. If the particles of the particulate fraction obtained from the sheet 5 are sufficiently small, the selection can be omitted and they can be immediately reprocessed. In this case, the sorting device 10 and the conveyor 13 are unnecessary.

When carrying out the method according to the drawing shown in FIG. 2, the waste material preliminarily crushed to a suitable size reaches the roll slits 24 formed between the two rollers 22, 23 via the feed hopper 21. The rollers 22 and 23 have the same diameter; However, the roller 73 rotates faster. The fine particles sheet 25 is formed on the roll 23, while the coarse fraction falls freely into the collecting hopper 26 arranged below and is conveyed to the feed hopper 21 through the conveyor 27. The sheet 25 is separated from the roller 23 by the scraper 25 and a second roll formed by the two rollers 30 and 31 (roller 31 rotates faster) through the chute 29. Reach the slit 32. The scraper 33 is also arranged on the roller 22, thereby removing residues which are also supplied to the roll slit 32 through the chute 34. After passing through the roll slit 32, the milled material can be sent to the next process.

The milled material can of course also be separated into granulation, fractions and particulate fractions in the second pair of rollers 30, 31 in the same way as in the first pair of rollers 22, 23. Scrapers 35 and 36 remove residue or remove sheets 37 from rollers 30 and 31, respectively. The milled material is collected in the hopper 38 and recovered through the outlet 39. Under the premise of using a mill equipped with a conveyor required for the above purpose, it is possible to convey the coarse fraction to the roll slit 32 or the roll slit 24 by this method.

In carrying out the third alternative, FIG. 3 shows a front view of the mill and FIG. 4 shows a side view. The main difference from the mill shown in FIG. 2 is that only a pair of rollers 42,43 were used instead of the second pair of rollers below the feed hopper 41, but this was longer and was pre-milled to a suitable size. The material passes through the roll slit 44. The sheet 45 of fine material is formed on the roller 43 which rotates faster, while the coarse fraction falls freely into the feed hopper 46 and is conveyed through the conveyor 47 to the feed hopper 41. . The sheet 45 is separated from the roller 43, which rotates faster by the scraper 48, and is located in the second zone 51 located outside the range of the feed hopper 41 via the chute 49 and the conveyor 50. Transported to (figure 4). Residues are also removed from the rollers 42 by the scraper 52, which also reach the conveyor 50 via the chute 53. After passing through the roll slit 44 in the zone 51, the coarse fraction falls into the chute 54 and adheres to the roller 75 and the sheet 75 located on the roller 43 of the zone 51 increment. The resulting residue is removed by scrapers 56 and 57 and conveyed together through the chute 54 to the outlet 58.

When carrying out the method according to the drawing shown in FIG. 5, the waste material pre-pulverized to an appropriate size reaches the roll slit 64 formed between the two rollers 62, 63 via the feed hopper 61. The rollers 62 and 63 have the same diameter: but the roller 63 rotates at a higher circumferential speed. The sheet of fine particles 65 is formed on the roller 63, while the coarse fraction falls freely into the collecting hopper 66 located below it and is fed to the feed hopper by means of a conveyor 67, for example a braking chain. It is returned to 61. The roller 63 forms a second roll slit 73 with the roller 72 that rotates more slowly, through which the sheet 65 passes. Scraper 74 removes residue from roller 72. The scraper 68 separates the sheet 65 from the roller 63, which is conveyed to the sorting device 70 through a chute 69. The coarse fraction removed by the sorting is conveyed through the chute 69 to the feed hopper 61: The particulate fraction is recovered via the outlet 76. Residues are removed from the rollers 62 by the scraper 71 and they are conveyed to the conveyor 67 together with the coarse fraction. When the rollers 72 rotate faster than the rollers 63, the roll slit 73 At least some of the sheets 65 are straightened by rollers 72 as they pass through.

When carrying out the method according to the drawing shown in FIG. 6, the waste material pre-crushed to a suitable size reaches the roll slit 84 formed between the two rollers 82, 83 via the feed hopper 81. The rollers 82 and 53 have the same diameter; However, roller 83 rotates at a higher circumferential speed. The finer sheet of 85 is formed on the roller 83, while the coarse fraction falls freely into the collection hopper 86 and is compressed by the compressed air from the nozzle 98 to the cellular wheel slew. By the sluice 97, it is conveyed to the supply hopper 81 via the cyclone 100 via the pipe 87. The sheet 85 is separated from the roller 83 by the scraper 88 and is conveyed to the sorting device 90 through the chute 89. The roller 82 is also removed by the scraper 91 and these residues are also conveyed to the sorting device 90 through the chute 92. The screened coarse fraction is conveyed to the feed hopper 81 via the pipe 93 via the cyclone 99 via the pipe 93 and by the compressed air from the nozzle 96, while Fractions are discharged through outlet 94 and are sent to an intermediate storage facility or sent directly to further processing. If the particles of the particulate fraction obtained from the sheet 55 are sufficiently small, the selection can be omitted and the particles can be further processed immediately. In this case, the sorting device 90 and the elements 95, 96, 93 and 99 of the delivery device can be removed. If the material is delivered by cooled compressed air, the material may be further cooled in addition to the cooling of the rollers.

A more preferred aspect of the invention is shown in FIG. The roller mill consists of three adjacent rollers 92, 93 and 94. The two outer rollers 92 and 94 rotate faster than the roller 93 in between. Three rollers form two roll slits 95 and 96. The material to be powdered first falls from the feed hopper 91 to the first roll slit 95, and a first sheet 97 of finely ground material is formed on the roller 94. The coarse fraction falls on the conveyor belt 98. Carried into the second roll slit 96, a second roller sheet 99 is formed on the roller 92. All remaining coarse fraction is conveyed by roller 93 to the first slit 95.

The conveyor belt 95 is at least stopped relative to the roller 92 so that no granulator flows between the roller 92 and the conveyor belt 98. The speed of the conveyor belt 98 corresponds to the circumferential speed of the low speed roller 93.

The sheets 97 and 99 are removed from the rollers by the wipers 100 and 101 and sent onto the screen 102 where the finely ground powder separates from too large particles. Too large particles are conveyed to the roll slit 95 via the channel 103.

Preparation of powder from foamed polyisocyanate-polyaddition product:

a) Preparation of Component A

60 parts by weight of a trifunctional polyether having a molecular weight of 6000 prepared by adding a total of 87% PO and 13% EO to TMP;

40 parts by weight of a charged polyether having a molecular weight of 6000 prepared by adding 68.75% PO, 14 58% EO and 16.66% TDI / hydrazine multiaddition product one block to 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 parts by weight of catalyst 3:

0.4 parts by weight of diethanolamine crosslinker:

1.0 parts by weight of the polysiloxane / polyether bloc copolymer stabilizer was mixed and homogenized by pride.

b) preparation of component B

TDI 80/20 and PMDl were mixed uniformly in a ratio of 70:30.

c) preparation of polyisocyanates / polyaddition products

105.95 parts by weight of component A is mixed with 48.5 parts by weight of component B, homogenized with an experimental stirrer (approximately 5 cm in diameter of the stirring blade) for 4 seconds from 4200 minutes ^-1 and then the reaction mixture is immediately placed in a mold treated with wax-based release agent. Preheated to 55 ° C. and closed the mold. After 10 minutes of molding time, the foamed polyisocyanate / polyaddition product was removed from the mold.

d) preliminary grinding

The product from the mold is preliminarily crushed into pieces of about 10-20 mm in a commercially available cutting mill (for example Pallmann Co., Zweibruken, obtained from Model PS-4-5), and then roller Added to wheat.

e) powdered

In the examples below, a type SK 6612 experimental roller mill (Berstorff, Hannover, Germany) as shown in FIG. 1 was used. The machine has two rollers with fixed bearings, each speed is individually controlled from 7 to 31.5 min ^-1 , the circumference is 62cm, the length is 45cm and the roll slit can be reduced to less than 0.1mm. The roller was not heated during the milling process.

In the milling test, the rotational speed was fixed at 30 minutes ⁻¹ for the roller ³ and 5 minutes 1 for the roller 2, and the width of the roll slit 4 was 0.1 mm. A small amount of 1 kg of the product prepared as above was added to the machine to obtain about 900 g of coarse flake falling directly from the roll slit 4 directly under the roller pairs 2, 3. These flakes still have a size of 5 to 10 mm. Physically separated from the material, about 100 g of powder was removed from the roller 3 using a scraper 8. The average particle diameter of this powder was measured at 200 µm.

f) measurement of particle diameter

The particle diameter was measured by a method of transferring an image to a computer using an optical microscope and then evaluating the image using image evaluation software. Here, the area of the particle at the right angle with respect to the direction of the observation on the observation plane was measured, and the diameter was measured by making this area close to the area of the circle. For particles that have a slightly out of spherical shape, this method gives good results compared to sieve analysis. The average particle diameter quoted is the particle size (diameter of the same mass) when 50% of all particles are smaller than the quoted value and 50% of all particles are larger than the quoted value.

Claims (9)

The pre-milled material to be milled is passed through a roll slit (4; 24; 44; 64) formed by rollers (2, 3; 22, 23; 42, 43; 62, 63) to obtain a coarse fraction and a particulate fraction. Two or more rollers (2,3; 22,23; 42,43; 62,63), which are separated and the coarse fraction is returned to the roll slit (4; 24; 44; 64) and the particulate fraction is sent to the next process. A method of powdering polyurethane, polycarbamide and / or polyurethane-polycarbamide materials in a roller mill, in which is rotated at different circumferential speeds, the roll slits (4; 24, 44, 64). While collecting and conveying the free-falling coarse fraction downstream of, the sheet (5; 25; 37, 45; 65) adhered to the roller (3; 23; 43; 63) having a higher circumferential speed. And wherein the particulate fraction is released separately from the coarse fraction. The method according to claim 1, wherein the sheet (5; 25; 37; 45; 65) consisting of the particulate fraction is removed and sent to the next procedure. 3. Method according to claim 2, characterized in that the particulate fraction is again classified into granulated and finely divided and the coarse particles are returned to the roll slit (4; 64). The sheet 65 bonded to the roller 63 passes through the roll slit 73 formed between the roller 53 and the third roller 72 by the roller 63. How to, The process according to claim 1, wherein the coarse fraction to be conveyed is cooled. The method according to any one of claims 1 to 4, wherein the material to be milled is a polyurethane rigid foam. 8. The method according to claim 1, wherein the material to be milled is a polyurethane flexible foam. 9. The method according to any one of claims 1 to 4, wherein the material to be milled is a polyurethane structural foam. The method according to any one of claims 1 to 4, wherein the material to be milled is a RIM material made of polyurethane, polyurethane-polycarbamide or polycarbamide.