SU1225847A1 - Method of producing polyethylene emulsifiable waxes - Google Patents

Description

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The invention relates to a process for the preparation of emulsifiable polyethylene waxes.

Products of this kind are used to produce self-glossy and easily removable high-hardness emulsions. Polyethylene waste by targeted thermal-oxidative degradation can be converted into products with waxy properties.

A method of producing polyethylene wax oxidates from high molecular weight olefin homo- or copolymers is known by preheating the starting product in an extruder at 553-523 K to melt viscosity 20,000 to 50,000 mPa-s, followed by thermal-oxidative destruction of the product obtained in the presence of oxygen or oxygen-containing gases. at 413-443 K, if necessary, in the presence of a catalyst (economic patent GDR No. 128.875, cl. С 08 F 8/50, 1975).

It is known that thermal-oxidative destruction of polyethylene is carried out in such a way that polyethylene or its mixture is subjected to thermal-oxidative destruction in the presence of oxygen or oxygen-containing gases and liquid, inert against reagents, additives at temperatures higher than the polyethylene melt index (GDR patent No. 12513Г, Cl. -C 08 F 8/06, 1974) ..

However, with such methods of destruction, along with the destruction of long polyethylene blocks of individual units, high molecular weight fractions of the order of up to 7% are found, the latter have a very negative effect on the quality properties and on the further processing of waxes. Since (THESE products only melt at a higher temperature and require a longer melting time during processing carried out almost exclusively through the melt, they are subject to greater thermal stress, which contributes to further crosslinking and discoloration and impedes emulsification. Emulsions obtained from these products, for some applications, are not sufficiently resistant to storage and are characterized by too much a tendency to defend due to the presence of high molecular weight fractions.

The purpose of the invention is to prevent the formation of high molecular weight fractions and to improve the quality of emulsions obtained from waxes.

The characteristics of the initial and final products are carried out with the following parameters.

Melt Index

g 10 minTGL 20996

Melt viscosity, mPa-s THL 0-51562

Acidic

number,

mg KOH / GTGL: 8418

Essential number

mg KOH / gtgl 8418

Penetrazium,

mm-10 .TGL 22854

The high molecular weight fraction is determined by gel chromatography (determination of Mg) and by determining the insoluble constituents contained in butyl acetate.

PRI me R s 1-3. 1.1 kg of polyethylene with a density of 0.921 g / cm and a melt index of 2.1 g / 10 min at 463 K are melted under nitrogen and pumped through a dosing pump to a stirred reactor. At 433–438 K, pure oxygen (50 L / h) is introduced with vigorous stirring and the product is subjected to thermo-oxidative degradation. After 2.5 hours of reaction, the product has an acid number of 19.8, an ester number of 15.9, and a melting viscosity at 413 K of 1,500. In order to prevent the formation of high molecular weight fractions during thermo-oxidative degradation, 1 hour is continuously added. 1.5–5 wt.% (Based on polymerizate) 10% liquor (example 15% NaOH, example 2 1.5% KOH, example 3 3% Ca (OH) 2). After a total reaction time of 3.5 hours, the reaction is terminated and the melt is granulated by spraying.

The table shows the amount of hydroxide used, and t-also the properties of the final products.

The emulsions obtained from these products are very homogeneous and stable during storage.

Example 4 (comparative). 1.1 kg of polyethylene used in Examples 1-3 is melted under nitrogen and pumped through a metering pump into

reactor with stirrer. The melt is intensively stirred at 433–438 K and 50 l / h of oxygen are passed through it. After 3.5 hours, the reaction is stopped and the melt is sprayed. Product properties are listed in the table. The resulting product, due to its high molecular weight fractions, is difficult to emulsify. Emulsions are easily settled.

Etc. and measure 5. A mixture of polyethylene and wax consisting of 10 kg. polyethylene with a density of 0.923 g / cm, with a melt index of 1-, 3 g / 10 min and 8 kg of polyethylene wax with a melt viscosity of 230 mPa-s melted under nitrogen, sent to a stirred reactor and treated there with oxygen (30 L / h) at 428 K.

After 3 hours, 4% by weight (based on the mixture) was continuously added through the dosing pump over 0.5 hours. 30% zinc acetate solution. Then the addition of oxygen is stopped, cooled to 390 K and the product is granulated. The final product has the following characteristics.

Acid number,

mg KOH / G35.1

Essential number

mg KOH / H40.8

Melting viscosity at 140 ° C

MPa-s371

Penetrazium,

mm-10

13

The product is completely soluble in butyl acetate and is very easy to emulsify. The M value determined by gel chromatography is 4730.

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0 5

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0

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According to the invention, homogeneous, slightly emulsifiable polyolefin waxes are obtained, which are characterized by slight heterogeneity due to the absence of high molecular weight fractions. Products of this kind can be melted at much lower temperatures and for a shorter time than the known ones. Therefore, in the processing processes, they are subject to significantly less thermal stress. The self-gloss emulsions obtained from these products are stable when stored at low, normal and low temperatures. Due to their good homogeneity, they do not remain and no deterioration of their properties occurs.

Particularly advantageous with this method is that, due to the addition of alkaline reagents, not only the formation of high molecular weight fractions is prevented, but acid groups also appear simultaneously. The resulting A-products with the addition of sufficient alkaline reagents can be compared with products obtained from known methods emulsifiable metal containing polyolefin waxes. Products of this kind are necessary to obtain easily removable self-flashing emulsions with high hardness.

The advantage of the proposed invention in comparison with the thermal oxidative waxes obtained by the destruction is the high cost-effectiveness of the method for obtaining the prepared products in comparison with the known dyeing methods.

Note. MjO - centrifuge agent

determined by chromatography on a molecular weight gel.

Compiled by A. Kulakov Editor N. Gunko Tehred L. Oleinik Proofreader I. Erdeyi

Order 2101/18 Circulation 470Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

Claims (1)

METHOD FOR PRODUCING POLYETHYLENE EMULSABLE WAXES by thermo-oxidative degradation of polyethylene at 428-438.K in the presence of oxygen, which is caused by the fact that, in order to prevent the formation of high molecular weight fractions and improve the quality of emulsions obtained from waxes, thermally oxidative degradation is carried out the number of 15.1 g of 19.8 mg KOH / g in the presence of 1.55 wt.% hydroxides of Na, K, Ca or Zn in the form of a 10-30% aqueous solution or aqueous suspension.