CS274027B1 - Method of waste polyethylene treatment - Google Patents

Abstract

The aim of the invention is a method of treatment of waste polyethylene from its production, colouring, dispatch or processing. This aim is achieved by homogenisation of polluted polyethylene of various colours and granule sizes and various melting index values in the homogenisation in such a reciprocal ratio that the resulting regranulate has geological characteristics allowing its use in the plastics industry, its washing and re-granulation in retruders of suitable construction. The subject of the invention can be used for regeneration of waste polyethylene.

Description

The present invention can be used for the recovery of waste polyethylene.

(11) (13) bl (51) Int. Cl. ⁵ C 08 L 23/06 C 00 J 11/06

CS 274027 Bl (2)

The present invention relates to a process for the treatment of waste polyethylene in which aa polluted polyethylene having a different melt index value is homogenized in a suitable ratio, treated if necessary by the addition of pigment and / or antioxidants and regranulated on a retractor of suitable construction.

It is known that in the manufacture of plastics a certain amount of waste polymer is required which is not suitable for direct processing in the plastics industry. Waste polyethylene is always produced during the start-up and shut-down of the line, during granulate sorting, during dyeing and shipping. The resulting exhaust polyethylene is extremely dirty, the granules are rdznofarebné non-standard size, and the bone ^1, the melt index ranges most often in the range of 0.2 to 30 g / 10 min. Such a polymer, which constitutes waste from manufacturers, is unusable in the plastics industry without treatment. These drawbacks are eliminated by the treatment of waste polyethylene, which consists in that waste polyethylene having a melt flow index of 0.2 to 30 g / 10 min is homogenized in such a proportion that the resulting product has the rheological properties of the melt material required by the respective plastics technology. If necessary, it is treated with the addition of colored pigmont and / or antioxidants, free of impurities and regranulated on a retractor of suitable construction.

Calculation of the melt index from the melt index of the input polyethylenes and the amounts of the individual components of the mixtures m ^ a ^ + + ...... + ^m x ^and x (sij ^{+ m} 2 ⁺ ..... ^{+ m} x ^la nij ai m - weight of individual components of polymer mixture m - total amount of polymer mixture «j to a _x - log ITTj to log ΧΤΤ _χ a - log ITT resulting or resulting melt flow index is a -» i »i ^{+ m} 2 * ₂ ⁺ .. .......... ⁺ ¥ χ m

To calculate the required amount of individual components to prepare the desired melt index from known melt indexes and the final amount of polymer blend, the following procedure can be used :.

m ^ and ^ + mjSj = m. and (3) ^m l ^{+ m} 2 " ^m m ₁ and m ₂ - unknown quantities of the individual components of the mixture i aa ₂ - log ITT ^ and log ITT ₂ m - final amount of polymer blend in kg / g - log ITT - required melt flow index

For a larger number of samples, the above procedure can be modified. The same rules apply for mixing the calculated rPE as for homogenizing the primary polymers after granulation. The advantage of this process is the preparation and utilization of waste polyethylene for the production of articles by technologies used in the plastics industry.

Claims (1)

Example It is necessary to determine the final ITT when mixing PE-LD granulates in the following ratio: CS 274027 Bl 600 kg rPE ABOUT ITT - 2 g / io min 500 kg rPE 0 ITT - 4 g / 10 min 400 kg rPE about ITT - 8 g / io min For this calculation we use formulas (2) ie., -r nijfi, + ^m 7 ^and 2 ^{+ m} 3 ⁿ 3 m = 600. log 2 + 500 log 4 + 400. log 8 1,500 a = 0.5619 = »ITT = 3.65 g / 10 min A mixture with a final ITT of 3.65 g / 10 min is prepared from the entrapped amounts of PE-LD entrained by ITT. The result is dependent on the precision of the melt flow index methodology. Example 2 It is necessary to prepare 800 kg PE-LD with ITT 4 g / 10 min if we have PE-LD polymers with ITT 2 and 8 g / 10 min. For the calculation we use the formula (3) and (4): m ^. log 2 + m ₂ log 8 = 800 log 4 ^m I ^{+ m} 2 “800 -«> ni | = 800 - m ₂ 800. log 2 + m ₂ (log 8 - log 2) = 800 log 4 n, ₂ = 800 (log 4 - log 2) log 8 - log 2 m ₂ = 399.9 kg m ₁ = 400.1 kg Example 3 Polluted low density polyethylene waste of non-standard granule size, melt index 1.12; 4.14; 13.06 g / 10 min was homogenized in a mechanical mixer in such a ratio (see previous calculation) that the resulting regranulate had a melt index value of 2.34 g / 10 min, was freed from impurities and regranulated on a chwag type extruder RT-100. The polymer was well processable on a blow molding line of conventional construction on a 0.05 and 0.1 mm thick film. Folia is a good use of ¹ in the packaging except for packaging foodstuffs. Example 4 Polluted, multicolored, waste low density polyethylene with a melt index of 0.66; 3.38; 19.87; 1.12 g / 10 min was homogenized and additive, 2% Rykolín-black BK type carbonate concentrate in such a ratio that the resulting regranulate had a melt index of 4.1 g / 10 min, washed and regranulated on a Čswag RT-line. 100th The re-granulated polyethylene has good processability ¹ NY in the blow line, the conventional construction mulch film 0.05 mm thick. Example 5 Polluted, waste polyethylene granulate of non-standard granule size, melt index 2.22; 1.52; 14.37; 2.7 g / 10 min was homogenized and stabilized with 0.05% phenolic antioxidant 2,6-di-tert-butyl-4-methylphenol in a mechanical homogenizer CS 274027 B1 at such a ratio that the resulting granulate had a melt index of 2.66 g / 10 min. The regranulate was processed on a conventional tubular film production machine to 0.1 mm thick film for conventional packaging purposes. The present invention can be used for the recovery of waste polyethylene resulting from its manufacture, dyeing or processing. 1 'it II I) m ε τ in Y n Λ h i! z u Waste polyethylene treatment process, characterized in that the waste polluted polyethylene having a melt index values in the range of 0.2 to 30 g / 10 min is homogenized according to the relations 1, 2, 3, 4 to a regranulate of theological properties enabling its treatment by known methods.