RU2324775C1 - Method of obtaining pack thread from polyethylene terephthalate - Google Patents

Abstract

FIELD: textiles, paper.

SUBSTANCE: invention relates to the technology used in production of pack thread from polyethylene terephthalate. Liquid polyethylene terephthalate, possibly from used beverage bottles, is etxruded at between 250 and 300°C through a slit draw plate. The obtained layer is cut into strips and subjected to phased thermal treatment with stretching. The stretched layer is fibrillated and intertwined into a pack tread using well known methods. The obtained thread with density of 2200 tex, has a rapture strength of up to 100 kgf at 2.2 mm thickness, and long service life even in harsh winter conditions.

EFFECT: increased strength and service life of the polyethylene terephthalate pack thread.

3 cl, 2 tbl, 2 ex

Description

The invention relates to a technology for the production of fiber products from polyester raw materials, mainly twine, used for packaging purposes, in particular in agriculture for tying hay bales, tying plants, etc.

The twine used in agriculture was originally made from fibers of plant origin - manila hemp, sisal. With the development of chemical synthesis technology, products made of chemical fibers, etc., were introduced into everyday life. Hay knitting twines began to be made from polymeric raw materials. Twine from plant materials was gradually replaced by twine from cheaper raw materials - polypropylene. In addition to lower prices, polypropylene fiber products have a number of technical advantages. Polypropylene twines are made mainly of fibrillated fissile film (www.kona.ru/publications/10, publ. 09/26/79).

An advantageous method for producing a polypropylene film is the flat-gap extrusion of molten polypropylene, then the formed film web enters the cooling device, then to the pulling, edging and winding ("Obtaining fibers from films", Overview, series: synthetic fibers, M., NIITEKHIM, 1977) .

Closest to the claimed is a method for producing film yarns used for the production of ropes, twines, etc., including flat-gap extrusion of a melt, for example, polyester (polyethylene terephthalate), cooling the resulting film, cutting it into strips, heat treatment during broaching, fibrillation of strips and twisting (“Obtaining fibers from films.” Overview, series: synthetic fibers, M., NIITEKHIM, 1977, p.9-14).

The known technical solution, as shown by the experiments conducted by the applicant, does not provide the production of twine from polyethylene terephthalate with sufficient strength for operation.

The present invention is to increase the strength of the twine obtained from polyethylene terephthalate. A whole series of information is known from the literature on the effect of various heat treatment and drawing conditions on the strength of chemical fibers, however, practical data on the hardening of extruded polyethylene terephthalate filaments were not found in available sources

The problem is solved in the claimed solution due to the fact that in the known method, including flat-gap extrusion of the polymer melt, cooling the polymer film, cutting it into strips, drawing the cut film by the first drive group, first heat treatment in the orienting hot air bath, pulling oriented strips by the second drive group , the second heat treatment in a heat-fixing air bath, pulling the heat-fixed strips by the third drive group, the subsequent fibrillation of the strips and twisting of twine as the starting polymer is polyethylene, including in the form of a crushed polyethylene terephthalate bottle, the first drive group is drawn into strips of film cut into strips at a speed of 14-20 m / min, the first heat treatment of the strips in the orienting hot air bath is carried out at a temperature of 80-140 ° C, the oriented strips are drawn through the second drive group at a speed of 40 -92 m / min, the second heat treatment of the strips in a heat-fixing air bath is carried out at a temperature of 110-190 ° C, and the strip is pulled by the third drive group at a speed of 60-110 m / min. In order to increase the plasticity of the polymer, 2-30% (wt) of polyethylene, for example, crushed cork from the same polyethylene terephthalate bottles, can be added to the extrusion feed.

The essence of the proposed method is as follows. A film of molten polymer (polyethylene terephthalate or its composition with polyethylene) with a temperature in the range of 250-300 ° C is continuously emerging from the head of a flat-slot extruder. The temperature of the film is reduced on a water-cooled drum, the cooled film on the drum is cut with pressed cutters into strips 100 mm wide. Cropped uneven edges are returned to the batch of the extruder. The strips are tucked into the first drive group, consisting of seven rolls, the rotation of which provides a pulling speed in the range of 14-20 m / min, while the strips receive the first stretch. Partially stretched strips enter the first air heating chamber (orientation chamber), where they are heated to a temperature of 80-140 ° C. The heated strips enter the second drive group, which also consists of seven rolls and provides a pulling speed of 40-92 m / min, here the strips get a second stretch. The strips are sent to the second thermoair chamber, where they are thermofixed at 110-190 ° C. The thermofixed strips are stretched by the third drive group, also consisting of seven rolls, at a speed of 60-110 m / min. Next, the stretched strips are fibrillated and sent for twisting by known methods. The number of rolls in the drive group is due to the properties of the polymer - with a smaller number of rolls, less reliable grip of the strips and less effective stretching are provided.

The inventive method is illustrated by the following examples.

Example 1. Dried to a moisture content of 0.02% polyethylene terephthalate waste (crushed bottle) was loaded into a heated single-screw flat-slot extruder. The extruder head was heated to 280 ° C and the polymer was extruded. A film 0.15-0.25 mm thick was cooled on a water-cooled drum to a temperature of + 60 ° C and cut into 7 strips 100 mm wide. The cut strips were tucked into the first drive group of seven rolls with a diameter of 240 mm, from where they were sent to the first air heating chamber. The heated strips were tucked into rolls (7 pcs) of the second drive group, from where they were fed into the second air heating chamber. After the second chamber, the heated strips were tucked into rolls (7 pcs) of the third drive group for final stretching. Then, the stretched strips were fibrillated and fed to twisting machines, on which twine with a density of 2200 tex and a diameter of 2.2 mm was obtained. Twine was tested for tensile strength on a dynamometer. The experimental results are shown in table 1.

Example 2. The experiments were carried out in the above order, only 2-30% (wt.) Crushed polyethylene cork from polyethylene terephthalate bottles were added to the batch of the extruder. The results are shown in table 2.

From table 2 it is seen that the addition of polyethylene really positively affects the ductility of the twine, however, the twine has a satisfactory strength only with the addition of 2-30% (wt.) Polyethylene.

The results of the experiments show that the claimed operating parameters of the method for producing twine from polyethylene terephthalate raw materials provide the feasibility of the method and the solution of the problem. Also confirmed the positive effect on the strength of the twine additives of polyethylene to the feedstock.

The method is tested in an industrial environment, the results are positive.

Table 1
The results of experiments to refine the mode of pulling PET strips No. p / p Speed of pulling in the first group of rolls, m / min The temperature in the first heating chamber, ° C Draw speed in the second group of rolls, m / min The temperature in the second heating chamber, ° C The speed of broaching in the third group of rolls, m / min Twine strength, kg one 12 70 thirty one hundred 55 45.6 2 fourteen 110 60 150 80 88.4 3 17 110 60 150 80 93.7 four twenty 110 60 150 80 97.5 5 22 110 60 150 80 68.8 6 16 80 60 150 80 63.3 5 16 90 60 150 80 90.6 6 16 one hundred 60 150 80 93.3 7 16 110 60 150 80 95.8 8 16 120 60 150 80 96.5 9 16 130 60 150 80 98.2 10 16 140 60 150 80 96.3 eleven 16 150 60 150 80 76.9 12 16 120 40 150 80 69.9 13 16 120 60 150 80 94.4 fourteen 16 120 80 150 80 92.8 fifteen 16 120 90 150 80 94.3 16 16 120 95 150 80 80.1 17 16 120 60 one hundred 80 63.5 eighteen 16 120 60 110 80 88.6 19 16 120 60 120 80 90,4 twenty 16 120 60 130 80 89.7 21 16 120 60 140 80 88.9 22 16 120 60 160 80 97.3 23 16 120 60 170 80 98.6 24 16 120 60 180 80 95.4 25 16 120 60 190 80 89.8 26 16 120 60 200 80 68.3 27 16 120 60 150 fifty 56.9 28 16 120 60 150 60 88.4 29th 16 120 60 150 70 87.6 thirty 16 150 60 150 80 90.2 31 16 120 60 150 90 94.4 32 16 120 60 150 one hundred 98.5 33 16 120 60 150 110 91.7 34 16 120 60 150 120 69.6

table 2
The results of experiments to study the effect of polyethylene additives No. p / p The addition of polyethylene, wt.% 5-point ductility Tensile strength, kg one one 0 81.3 2 2 one 95.0 3 fifteen 2 96.2 four thirty four 97.9 5 32 5 75.4

Claims (3)

1. A method of producing packaging twine from polyethylene terephthalate, including flat-gap extrusion of polymer melt, cooling the polymer film, cutting it into strips, drawing the cut film with the first drive group at a speed of 14-20 m / min, first heat treatment in an orienting hot air bath at 80-140 ° C, stretching the oriented strips by the second drive group at a speed of 40-92 m / min, a second heat treatment in a heat-fixing air bath at 110-190 ° C, pulling by a third drive group at a speed of 60-110 m / min, stiff fibrillation of the strips and twisting them into twine. 2. The method according to claim 1, characterized in that the crushed polyethylene terephthalate bottle is used as the starting polymer. 3. The method according to PP.1 and 2, characterized in that in the raw materials for extrusion add 2-30 wt.% Crushed bottle caps made of polyethylene.