WO2002008324A1

WO2002008324A1 - Recycling plastic

Info

Publication number: WO2002008324A1
Application number: PCT/EP2001/008112
Authority: WO
Inventors: Stefan Küpper; Thomas Wershofen; Wolfgang Preibsch
Original assignee: Ecolab Gmbh & Co. Ohg
Priority date: 2000-07-22
Filing date: 2001-07-13
Publication date: 2002-01-31
Also published as: DE10035780A1; PL365737A1; EP1305360A1

Abstract

The invention relates to a method for processing used plastic bodies. Said plastic bodies are comminuted and during and/or after the comminution process are treated with an alkaline aqueous solution which contains a) an alkalinity donor and the following other components, at least b) one complexing agent or a complexing agent in the form of a salt chosen from the groups of amino carboxylic acids, phosphonic acids, polycarboxylic acids and/or c) an acid, particularly an acid in the form of a salt chosen from gluconic acid, lactic acid, citric acid, glycolic acid, acetic acid, propionic acid, succinic acid, glutaric acid, adipinic acid, butanedioic acid, fatty acids containing 8 - 18 carbon atoms per molecule, phosphoric acid or mixtures of said acids and/or d) a de-foaming component. The invention also relates to the use of communited plastic bodies obtained according to the inventive method in the production of new plastic bodies, in addition to said plastic bodies which exhibit unique properties.

Description

"Plastic Recycling"

The invention relates to a method for processing used plastic bodies and the use of plastic materials obtained from the used plastic bodies in the production of new plastic bodies. Another object of the invention are the new plastic bodies obtained in this way due to their special properties.

For the production of, for example, new plastic bottles, used plastic material that has already been partially processed is used today. The higher the quality of the processed used plastic material, which is visually recognizable, for example, by the extent of the color brightening, the higher the proportion that can be used in the production of new plastic bottles.

For example, it is known from Japanese publication JP 11090934 (273300) that PET bottles are first crushed and then roughly washed with water. The PET flakes are then washed with organic solvents and recycled through further measures.

Emerging Technologies in Plastic Recycling (ACS Symp. Ser. 513), Washington: ACS, 1992, pp. 196-204 describes a process that allows 10 to 20% of the material to be made in the production of new PET bottles use used PET bottles. In this preparation process, the polymeric structure of the PET (from the used PET bottles) is broken up or de-polymerized. After going through several process steps, the depolymerized material is polymerized again together with new PET starting material. The above methods are hardly used in practical application. For example, when processing plastic bottles, for example PET bottles (polyethylene terephthalate), the used PET bottles are usually perforated and pressed in one process step. Appropriate measures result in crushed, for example chopped, PET. In order to achieve the highest possible quality of the resulting granulate, undesirable residues must be removed from and from the shredded PET.

The residue can be removed, for example, by washing out with aqueous solutions. After the washing process, foreign substances (lids, labels etc.) are separated off by flotation and / or separators. The washed and dried PET is now extruded and granulated.

In flotation, air is pressed or sucked through the wash liquor. Air bubbles combine with the residue particles and / or foreign substances and form a foam on the water surface, which is removed with cloth scavengers.

The washing treatment of the comminuted plastic material is usually carried out at alkaline pH values in the presence of alkali hydroxides or other alkali donors and optionally foaming surfactants at temperatures around 90.degree. The washing treatment takes about 20 minutes.

For example, the surfactant-containing product Oakite RC 83 E from FA is already used in processes. Oaktite Europe GmbH, Trakehner Str., Frankfurt / Main dissolved in water in 1-2% concentration and used for washing treatment. The product contains about 40% alkali hydroxide. In addition, there are about 19% by weight of Cg -C ₄ fatty alcohol with about 10 ethoxyl groups and about 11% by weight of the Na salt of the Cs fatty acid in the product. The pH of the wash liquor is around 10-11.

However, the existing process has not yet been satisfactorily resolved with regard to the quality of the processed plastic material and the process parameters, such as washing time and temperature. For quality reasons, only a proportion of <10% of PET material that comes from the reprocessing of used PET bottles can currently be used in the production of new PET bottles.

Accordingly, the object of the present invention was to improve the processing of used plastic materials in order to achieve improved quality of the processed plastic material and possibly more favorable processing conditions.

The present invention relates to a method for processing used plastic bodies, wherein these plastic bodies are crushed during processing and treated with an alkaline aqueous solution during and / or after the crushing process

a) an alkalinity donor and at least as a further component b) a complexing agent or the salt form of a complexing agent selected from the groups of amino carboxylic acids, phosphonic acids, polymeric carboxylic acids and / or c) an acid or the acid form of an acid selected from gluconic acid, lactic acid, citric acid , Glycolic acid, acetic acid, propionic acid, succinic acid, glutaric acid, adipic acid, succinic acid, fatty acids with 10 to 18 carbon atoms per molecule, phosphoric acid or from mixtures of these acids and / or d) a defoaming component.

It is preferred if the alkalinity dispenser a) in the alkaline-aqueous solution is between 0.01 and 10% by weight, based on the total alkaline-aqueous solution, and it is particularly preferred if the alkalinity dispenser a) is an alkali hydroxide selected from sodium - and is potassium hydroxide.

The alkaline aqueous solution preferably has a pH greater than 9. The proportion of a complexing agent b) in the alkaline-aqueous solution, based on the total alkaline-aqueous solution, is preferably between 5 and 40,000 ppm.

In the event that component b) is selected from the group of amino carboxylic acids, nitrilotriacetic acid, ethylenediaminetetraacetic acid, methylglycinediacetic acid, dicarboxymethyl-L-glutamic acid, serine diacetic acid, imidosuccinic acid and / or their salts in each case are preferably selected.

If component b) is selected from the group of polycarboxylic acids, for example polyacrylic acids and copolymers of maleic anhydride and acrylic acid and the sodium salts of these polymer acids are suitable. Commercial products are e.g. B. Sokalan® CP 5 and PA 30 from BASF, Alcosperse® 175 and 177 from Alco, LMW® 45 N and SPO2 ND from Norsohaas. Suitable native polymers include, for example, oxidized starch (e.g. DE 42 28 786) and polyamino acids such as polyglutamic acid or polyaspartic acid, e.g. B. from Cygnus, Bayer, Rohm & Haas, Rhône-Poulenc or SRCHEM.

In the event that component b) is selected from the group of phosphonic acids, 1 hydroxyethane-1, 1-diphosphonic acid, diethylenetriaminepentamethylenephosphonic acid or ethylenediaminetetramethylenephosphonic acid and in each case their alkali metal salts are suitable.

It is preferred if the acid or the salt form of the acid c) in the alkaline-aqueous solution, based on the total alkaline-aqueous solution, is between 5 and 20,000 ppm, and it is particularly preferred if the acid c) is selected from gluconic acid , Lactic acid, citric acid, fatty acid with 10 to 18 carbon atoms per molecule.

It is further preferred if the alkaline aqueous solution as defoaming component d) one or more surfactants selected from the groups the nonionic surfactants, the phosphoric acid esters and their salts and the silicone compounds.

The proportion of surfactants d) in the alkaline-aqueous solution, based on the total alkaline-aqueous solution, is preferably between 5 and 20,000 ppm.

It is particularly preferred if a 1% alkaline aqueous NaOH solution containing about 200 ppm of a defoaming component d) has a defoaming effect in the Götte test at 20-90 ° C., very particularly preferably at 50-80 ° C is detectable.

In many cases, foam is an undesirable side effect when using cleaning agents. To avoid cleaning and application problems, the foam-forming effect of raw materials and application solutions must be checked and recorded using measuring technology.

The defoamer test is carried out in a foam blow apparatus according to Götte (DIN 53902).

200 ml of the solution to be tested are placed in a 1 L measuring cylinder at 20 ° C, 40 ° C, 50 ° C and 60 ° C, respectively. With the help of a perforated disk, foam is created by immersing and submerging 100 times. The foam height above 200 ml is read off immediately after beating. Then this process is repeated 4 more times, so that a total of 500 blows were carried out. Duplicate determinations with standards and comparative samples are always to be carried out and the mean value is to be formed from the read values.

In addition, dodecylbenzenesulfonate-triethanolamine salt can be added in 100 ppm steps and the experiment repeated under these more stringent conditions. By comparing different alkaline aqueous solutions, it can be determined whether the addition of certain components has a defoaming effect. effect. If this is the case, then this component can be referred to as a component with defoaming properties.

It is also particularly preferred that mixed ethoxylates / propoxylates of branched or unbranched alkyl alcohols having 8 to 22 carbon atoms, very particularly preferably 12 to 22 carbon atoms, are present in the alkyl chain as nonionic surfactants.

It is equally preferred that the non-ionic surfactants end-capped ethoxylates of branched or unbranched alkyl alcohols having 8 to 22 carbon atoms, very particularly preferably 12 to 22 carbon atoms, are present in the alkyl chain, the end-group capping preferably being a butyl ether or methyl ether closure.

It is particularly preferred that alkyl polyglucosides having 8 to 14 carbon atoms in the alkyl group and 1 to 5 glucose units are present as nonionic surfactants.

Depending on the process and requirements, the alkaline aqueous solution can contain additional hydrotropes or solubilizing agents.

It is further preferred if the hydrotropes or solubilizing agents additionally contained in the alkaline aqueous solution are selected from sulfonates / sulfonic acids and in particular from cumene, xylene, octyl, naphthyl and alkylbenzenesulfonates / sulfonic acids, the last If the alkyl group contains between 6 and 16 carbon atoms, or mixtures of these compounds and / or other compounds which act as solubilizers.

In a preferred embodiment, the process temperature at which the comminuted plastic body is treated with the alkaline aqueous solution is between 40 and 90 ° C., particularly preferably between 60 and 80 ° C.

The treatment time of the comminuted plastic bodies with the alkaline aqueous solution is preferably between 1 and 120 minutes, particularly preferably between 1 and 40 minutes and very particularly preferably between 5 and 15 minutes.

It is further preferred that the plastic bodies to be treated are selected at least in part from polymers selected from polyethylene terephthalate (PET), polyethylene naphthenate (PEN), polycarbonate (PC), polyethylene (PE), polyvinyl chloride (PVC), polyamide (PA), Polyurethane (PU) exist.

It is preferred to use the method according to the invention for processing single-use or reusable plastic bottles from the food sector.

The process according to the invention is preferably carried out with an alkaline aqueous solution which additionally contains at least one peroxidic compound selected from hydrogen peroxide and / or peracetic acid, perpropionic acid, persuccinic acid, perglutaric acid, peradipic acid, succinic acid, perfettic acids with 8 to 18 carbon atoms per molecule.

A further preferred embodiment of the process is present if the alkaline aqueous solution additionally contains ester quats.

The term "ester quats" is generally understood to mean quaternized fatty acid triethanolamine ester salts. These are known substances which can be obtained by the relevant methods of preparative organic chemistry. In this connection, reference is made to the international patent application WO 91/01295 (Henkel), according to which triethanolamine is partially esterified with fatty acids in the presence of hypophosphorous acid, air is passed through and then quaternized with dimethyl sulfate or ethylene oxide. German Patent DE-C1 4308794 (Henkel) also discloses a process for the preparation of solid ester quats. in which the quaternization of triethanolamine esters is carried out in the presence of suitable dispersants, preferably fatty alcohols.

The quaternized fatty acid triethanolamine ester salts follow the formula (I) R ⁴

[R ¹ CO- (OCH2CH2) mOCH2CH ₂ - ⁺ -CH2CH2θ- (CH2CH ₂ O) nR ² ] X ^" (I)

I

CH ₂ CH ₂ θ (CH ₂ CH ₂ O) pR ³

in which R ¹ CO for an acyl radical with 6 to 22 carbon atoms, R ² and R ³ independently of one another for hydrogen or R ¹ CO, R ⁴ for an alkyl radical with 1 to 4 carbon atoms or a (CH CH2θ) _q H group, m , n and p in total stand for 0 or numbers from 1 to 12, q stands for numbers from 1 to 12 and X stands for halide, alkyl sulfate or alkyl phosphate. Typical examples of ester quats which can be used in the context of the invention are products based on caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, isostearic acid, stearic acid, oleic acid, elaidic acid, arachic acid, behenic acid and erucic acid and also their Technical blends, such as those that occur when natural fats and oils are split. Technical C ₂ / i8 coconut fatty acids and in particular partially hardened Ci _6/18 tallow or palm fatty acids and C _6/18 fatty acid cuts rich in elaidic acid are preferably used. The fatty acids and the triethanolamine can be used in a molar ratio of 1.1: 1 to 3: 1 to produce the quaternized esters. With regard to the application properties of the ester quats, an application ratio of 1.2: 1 to 2.2: 1, preferably 1.5: 1 to 1.9: 1 has proven to be particularly advantageous. The preferred ester quats are technical mixtures of mono-, di- and triesters with an average degree of esterification of 1.5 to 1.9 and are derived from technical Cι _{6 /} ιs- tallow or. Palm fatty acid (iodine number 0 to 40). From an application point of view, quaternized fatty acid triethanolamine ester salts of the formula (I) have proven to be particularly advantageous in which R ¹ CO for an acyl radical having 16 to 18 carbon atoms, R ² for R ¹ CO, R ³ for hydrogen, R ⁴ for a methyl group , m, n and p are 0 and X is methyl sulfate.

In addition to the quaternized fatty acid triethanolamine ester salts, quaternized ester salts of fatty acids with diethanolalkylamines of the formula (II) are also suitable as esterquats. R ⁴

[R ¹ CO- (OCH2CH2) mOCH2CH2-N ⁺ -CH ₂ CH2θ- (CH2CH2θ) nR ² ] X ^" (II)

in which R ¹ CO stands for an acyl radical with 6 to 22 carbon atoms, R ² for hydrogen or R CO, R ⁴ and R ⁵ independently of one another for alkyl radicals with 1 to 4 carbon atoms, m and n in total for 0 or numbers from 1 to 12 and X represents halide, alkyl sulfate or alkyl phosphate.

Finally, a further group of suitable ester quats are the quaternized ester salts of fatty acids with 1,2-dihydroxypropyl dialkylamines of the formula (III),

R ⁶ O- (CH ₂ CH ₂ O) _m OCR ¹

[R ⁴ -N ⁺ -CH ₂ CHCH ₂ O- (CH ₂ CH ₂ O) _n R ² ] X ^" (III) ie in R ¹ CO for an acyl radical having 6 to 22 carbon atoms, R ² for hydrogen or R ¹ CO, R ⁴ , R ⁶ and R ⁷ independently of one another are alkyl radicals having 1 to 4 carbon atoms, m and n in total are 0 or numbers from 1 to 12 and X is halide, alkyl sulfate or alkyl phosphate.

The process according to the invention is preferably carried out with an alkaline aqueous solution which contains at least fluorosurfactants as defoamers d).

It is also preferred that in the process according to the invention alkali hydroxide is dissolved in water in one step and to this alkaline aqueous solution one or more additives are added which contain one or more of components b) to d) and particularly preferably in the form of aqueous solutions, gel, emulsion, paste, dispersion, powder, granules, flakes, beads, tablets, block-like moldings, extrudate.

In a particularly preferred form, the additives mentioned in the previous paragraph contain additional tracer substances, such as halides, for example Potassium iodide, or like fluorescent dyes, as reference substances for determining the concentration of the active substances present in the alkaline aqueous solution by, for example, ion-selective measurement or quantitative measurement of the fluorescent portions of the solution.

In the process according to the invention, the surface of the comminuted plastic bodies is preferably brought into contact with the alkaline aqueous solution by dipping and / or by means of auxiliary means, such as, for example, a spray device and, if appropriate, by mechanical action.

Another object of the present invention is that the crushed plastic bodies treated in a method according to the invention are used in the production of new plastic bodies. Due to the high quality of the shredded plastic bodies, for example, in the production of new PET bottles, more than 10%, particularly preferably more than 20%, of the PET starting material can come from the reprocessing according to the method according to the invention. The qualitative advantages that the use of material prepared according to the invention offers are evident, inter alia, from the examples.

An object of the present invention also consists of plastic bodies which can be obtained by recycling plastic material prepared according to the invention. Depending on the proportion of material processed according to the invention and the individual conditions of the method for processing used plastic bodies, the properties of the newly produced plastic body can advantageously be set.

For example, it is common in beverages manufacturing companies that the washed plastic reusable bottles, for example based on PET, PEN or PC, are subjected to an automatic inspection for freedom from residues. In practice, the automatic inspection has the disadvantage that after the washing process on the inside and / or outside surface of the reusable plastic bottles can still have drops of water left behind. Depending on the size of the water drops, this can lead to them being detected as residues due to the sensitivity of the automatic inspection device, and consequently the affected washed plastic reusable bottles to be removed. Because of this "incorrect discharge", plastic bottles are disposed of in many factories, which are actually still in perfect condition. Since the bottle pool is a very important economic asset for a beverage manufacturing company, there is a great need, the number of To keep "false discharges" as low as possible due to water droplets remaining on the surface of washed plastic reusable bottles.

This problem is solved by reusable plastic bottles, in the production of which plastic material prepared according to the invention is used.

It is preferred here if an organofluorine component, particularly preferably an additional organofluorine polymer, such as polytetrafluoroethylene and / or an organofluorine surfactant, has been added in the preparation process.

It is also preferred if an organofluorine defoamer was used as defoamer d) in the preparation process.

Examples

In order to arrive at criteria which enable the teachings according to the invention to be differentiated from the prior art, standard parameters for carrying out the experiment are first defined.

Used 1.5L PET reusable bottles with labels of the same type (Coca Cola label, stomach and back label) and the same amount (10 - 18g / m ² ) of labeling adhesive (synthetic resin glue with casein content) are used as the starting material. A reusable PET bottle weighs about 80 to 100g. There is an average of about 0.5 g of labeling adhesive and about 1 g of label on a reusable PET bottle.

The reusable PET bottles equipped in this way are subjected to identical wash cycles in the same bottle washer with highly loaded lye (COD> 10,000 mg / L) under identical conditions.

These PET bottles pretreated in this way are chopped into pieces of approx. 1 x 1 cm. About 10 g of the pieces are selected per experiment so that the proportion of labeled PET surface and labeling adhesive per test is approximately the same. These PET pieces are placed in 1000 ml of the inventive or the comparative solutions and stirred at 80 ° C. with a commercially available magnetic laboratory stirrer with a stirring speed of approx. 400 revolutions / min for 10 minutes. After the time has elapsed, the PET pieces are removed from the lye using a sieve.

The inventive or the comparative solutions are alkaline aqueous solutions which contain 0.5% by weight of NaOH and 0.3% by weight of an additive A _v (comparative embodiment according to the prior art) or an additive A _x (inventive embodiment) ,

The recipes for additive A _v and additive A _x can be found in table 1. Table 1: Formulations of additives A _v and A _x : proportions in% by weight based on the total additive (remainder to 100% by weight = water)

that is used in 1-2% concentration in water. In order to To produce comparability in the present test series, by adding the additive A * _v defined in the table to the 0.5% NaOH, a comparable alkaline-aqueous solution corresponding to the prior art is produced.

To evaluate the tests according to the invention or the comparison tests, various criteria are to be used which are weighted in the context of the visual evaluation (Table 2).

^* Flotation: the percentages correspond to the percentage of dirt discharged from the fleet The tests according to the invention or the comparative tests were carried out in the manner already described and the visual assessment was then carried out. The results of the tests are summarized in Table 3.

Table 3: Test results depending on the additive to 0.5% NaOH solution

As can be seen from Table 3, the use of certain selected additive combinations, or of alkaline-aqueous solutions which contain certain active ingredients, offers a number of advantages in the process for the preparation of PET reusable bottles, which is both in the treatment process and in the quality of the processed PET material.

Claims

claims

1. A process for the preparation of used plastic bodies, these plastic bodies being comminuted during the preparation and being treated with and / or after the comminution process with an alkaline-aqueous solution which a) an alkalinity donor and at least as a further component b) a complexing agent or the salt form of a complexing agent selected from the groups of amino carboxylic acids, phosphonic acids, polymeric carboxylic acids and / or c) an acid or the salt form of an acid selected from gluconic acid, lactic acid, citric acid, glycolic acid, acetic acid, propionic acid, succinic acid, Contains glutaric acid, adipic acid, succinic acid, fatty acids with 10 to 18 carbon atoms per molecule, phosphoric acid or from mixtures of these acids and / or d) a defoaming component.

2. The method according to claim 1, characterized in that as an alkalinity dispenser in the alkaline aqueous solution, based on the total alkaline aqueous solution, between 0.01 and 10% by weight of an alkali metal hydroxide selected from sodium and potassium hydroxide are present.

3. The method according to any one of claims 1 or 2, characterized in that the temperature at which the comminuted plastic body is treated with the alkaline aqueous solution is between 40 and 90 ° C.

4. The method according to any one of claims 1 to 3, characterized in that the treatment of the comminuted plastic body with the alkaline aqueous solution takes between 1 and 120 minutes.

5. The method according to any one of claims 1 to 4, characterized in that the plastic body selected at least in part from a polymer Polyethylene terephthalate (PET), polyethylene naphthenate (PEN), polycarbonate (PC), polyethylene (PE), polyvinyl chloride (PVC), polyamide (PA).

6. The method according to any one of claims 1 to 5, characterized in that the plastic body represents disposable or reusable plastic bottles for the food sector.

7. The method according to any one of claims 1 to 6, characterized in that between 5 and 40,000 ppm of the complexing agent b) are present in the alkaline-aqueous solution, based on the total alkaline-aqueous solution.

8. The method according to any one of claims 1 to 7, characterized in that between 5 and 20,000 ppm of the acid or the salt form of the acid b) are present in the alkaline-aqueous solution, based on the total alkaline-aqueous solution.

9. The method according to any one of claims 1 to 8, characterized in that between 5 and 20,000 ppm of a surfactant component are present in the alkaline-aqueous solution, based on the entire alkaline-aqueous solution, as defoamer d).

10. The method according to any one of claims 1 to 9, characterized in that the alkaline aqueous solution additionally contains at least one hydrotrope.

11. The method according to any one of claims 1 to 10, characterized in that in the alkaline aqueous solution in addition at least one peroxidic compound selected from hydrogen peroxide and / or peracetic acid, perpropionic acid, persuccinic acid, perglutaric acid, peradipic acid, succinic acid, perfett acids with 8th up to 18 carbon atoms per molecule is contained.

12. The method according to any one of claims 1 to 11, characterized in that esterquats are additionally contained in the alkaline aqueous solution.

13. The method according to any one of claims 1 to 12, characterized in that at least one fluorosurfactant is contained in the alkaline aqueous solution as defoaming component d).

14. The method according to any one of claims 1 to 13, characterized in that the alkaline aqueous solution can be obtained by dissolving alkali hydroxide and adding one or more additives.

15. The method according to claim 14, characterized in that the additive or additives are present as an aqueous solution, gel, emulsion, paste, dispersion, powder, granules, flakes, beads, tablets, block-like shaped bodies, extrudate.

16. The method according to any one of claims 14 or 15, characterized in that the said additive or additives contain additional tracer substances.

17. The method according to any one of claims 1 to 16, characterized in that the surface of the comminuted plastic body is brought into contact with the alkaline aqueous solution by dipping and / or by means of aids, such as a spray device and optionally by mechanical action.

18. Use of the crushed plastic body treated according to claims 1 to 17 in the production of new plastic body.

19. Plastic body, which were made from used plastic bodies, which were prepared according to a method according to any one of claims 1 to 17.

20. Plastic body according to claim 19, characterized in that an organofluorine compound is used in the preparation process as a defoamer d).

21. Plastic body according to one of claims 19 or 20, characterized in that in the preparation process according to one of claims 1 to 17, an additional component selected from organofluorine surfactant and organofluorine polymer, such as polytetrafluoroethylene, is added.