JPS6234624B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a packing band made of polyethylene terephthalate resin and a method for manufacturing the same. (Prior Art) Binding bands for heavy packaged items include binding bands made of processed natural fibers or synthetic fibers, and binding bands made of steel. The former has disadvantages such as load collapse due to stress relaxation after bundling and breakage due to insufficient tension and knot strength, while the latter has problems of corrosion and danger when unpacking. Therefore, packing bands made of polyethylene terephthalate resin were considered as an alternative binding band. Conventional bands made of polyethylene terephthalate resin are mainly one-step stretch molded.
In addition, polyethylene terephthalate resin with an intrinsic viscosity (IV value) of 0.90 or less is used as a raw material. (Problems to be Solved by the Invention) However, it has the following drawbacks. (a) Insufficient strength. (b) Heat sealing strength is low and there are many variations in heat sealing. (c) The shrinkage rate at high temperatures is large and it cannot be used in high temperature locations. (d) Poor weather resistance. There are drawbacks such as. Several proposals have been made for two-stage stretch molding of polyethylene terephthalate resin in the past, but most of them were aimed at increasing the transparency of the film, and in addition to the same drawbacks as mentioned above, they also have drawbacks such as vertical cracking. be. (Means for Solving the Problems) The inventor believes that the reason why conventional polyethylene terephthalate molded products have many drawbacks as described above is that
The present invention was created by focusing on the problem of resin viscosity and the two-stage stretching conditions. The present invention is a polyethylene terephthalate resin band whose raw material has an inherent viscosity (IV value) of 0.90 to 1.20, and the polyethylene terephthalate resin packing band is stretched in the length direction at a total stretching ratio of 3 to 6 times. , and polyethylene terephthalate with an intrinsic viscosity (IV value) of 0.90 to 1.20, dried in a drying hopper with a dehumidifier of an extruder, is melt-extruded from a mold, and the extruded molten resin is cooled in a first water tank to form a strip. This strip-shaped body is stretched at a temperature of 85 to 100°C to a stretching ratio of 3 to 4.5 times as the first stage of stretching, and then as the second stage of stretching.
Stretched at a high temperature of 250 to 350°C to give a total stretching ratio of 4.6 to 6 times in the length direction, and then heat treated by passing through a heat treatment tank at a temperature of 180 to 280°C at a take-up speed with a down rate of 0 to 5%. A method for manufacturing a packing band made of polyethylene terephthalate resin. (Function) By using polyethylene terephthalate resin with an intrinsic viscosity (IV value) of 0.90 to 1.20, it has good heat sealing properties, and the total stretching ratio is 3 to 6 times, which prevents vertical cracking and stretch breakage. strength is improved. The two-stage stretching process promotes crystallization in the direction perpendicular to the fiber axis and in the axial direction, and the heat treatment after the two-stage stretching removes the undulating distortion and promotes crystallization. (Example) The packing band made of polyethylene terephthalate resin of the present invention and the manufacturing method thereof will be described in detail below. Polyethylene terephthalate resin with an intrinsic viscosity (IV value) of 0.90 to 1.20 is used as a raw material. Polyethylene terephthalate with an intrinsic viscosity of 0.90 to 1.20 is dried at a temperature of 150°C for about 4 hours in the drying hopper 1 with a dehumidifier of the extruder 2 to reduce the moisture content to 0.02% or less.
The melt is extruded from mold 3 through a cylinder set at 240-285°C. This extruded molten resin is heated to a water temperature of 50℃.
After cooling in the first water tank 4 set to
Then, it is taken up and made into a strip 6. This strip-shaped body 6 passes through a first drawing tank 7 and is taken up by a second taking-off machine 8 . In the first drawing tank 7, the strip 6 is heated to 85°C or more with hot water or steam.
It is heated to 100°C and the stretching ratio is 3 to 4.5. Stretching is performed by adjusting the rotational speeds of the first drawing machine 5 and the second drawing machine 8. The thus stretched strip 6 further passes through a second stretching tank 9 and is transferred to a third drawing machine 1.
Send to 0. In this second drawing tank 9, the strip 6 is heated to a temperature of 250 to
Heating in a high temperature atmosphere of 350℃, stretching ratio is 1.2 ~
Set it to 1.5. Incidentally, the total stretching ratio in the length direction including the first stage stretching is 4.6 to 6. Stretching ratio 4.6
In the following cases, sufficient strength cannot be obtained, and in particular, in the case of 3 or less, the desired strength cannot be obtained. Also, the stretching ratio is 6
In the above cases, vertical cracks and stretch cuts occur. The belt-shaped body stretched in two stages in this way becomes a band 15, which is embossed with an embossing roll 11 to disturb the molecular orientation arranged in the length direction of the belt-shaped body, and then passed through a heat treatment tank 12. After being heat treated with a dry heater at 180 to 280°C and cooled in a second cooling tank 13, it is passed through a fourth take-up machine 14 to a take-up device 16.
Wind it up. In addition, the third collection machine 10 and the fourth collection machine 1
The take-up speed ratio with No. 4 is the same or the take-up speed of the fourth take-up machine 14 is reduced by about 5%. After two-stage stretching, heat treatment is performed. This has the effect of removing undulating distortion due to orientation and promoting crystallization. Down rate is usually 0~
5% so that the band does not have too much tension when passing through the heat treatment tank. If a heat-treated band is wound onto a winding drum without being rolled down, problems such as shrinkage of the band after winding and destruction of the paper tube supporting the band will occur. Next, a band made of polyethylene terephthalate produced by the above method, a band made of polyethylene terephthalate that was stretched in one step with the same intrinsic viscosity as the present invention, and a band made of polyethylene terephthalate that was stretched in two steps with an intrinsic viscosity of 0.90 or less,
Table 1 shows a comparison of physical properties with a polyethylene terephthalate band that has been stretched in one step with an intrinsic viscosity of 0.90 or less. Both bands are 16mm wide and 0.6mm thick.

[Table] As shown in Table 1, the polyethylene terephthalate resin band produced by the method of the present invention has good tensile strength and fusion strength, low shrinkage rate, good weather resistance, and does not crack vertically. Because it uses polyethylene terephthalate resin with a high intrinsic viscosity (IV value), it has good heat-sealing properties, and even though it is stretched at a high magnification, there is no vertical cracking and the strength can be improved. On the other hand, when polyethylene terephthalate resin is stretched at a temperature of 150° C. or higher, oriented crystallization in the fiber axis direction progresses and the strength increases. In the second stretch forming of the present invention, crystallization in the direction perpendicular to the fiber axis (first stage) and crystallization in the direction of the fiber axis (second stage) are advanced in each step, and a step (heat treatment) to remove stretching strain. By separately providing a band, the band is free from vertical cracks, has high strength, and has a low shrinkage rate at high temperatures. The weather resistance of the polyethylene terephthalate resin band is far superior to other plastic bands, with no significant decrease in strength even after two years of outdoor exposure. It should be noted that in the present invention, the polyethylene terephthalate resin is produced by polycondensation of terephthalic acid and ethylene glycol, and when it is heated and melted, it will hydrolyze and cause a decrease in viscosity if it contains moisture. This results in a significant deterioration in quality. Therefore, in normal molding, the raw material is dried in a drying hopper equipped with a dehumidifier at 150°C for 4 hours or more to reduce the moisture content of the raw material to 0.02% or less. The following (Table 2) shows the physical properties when molded according to the manufacturing conditions of the present invention (Table 3) while changing the drying state of the raw materials. was dried at 150° C. for 4 hours in a drying hopper equipped with a dehumidifier according to an example of the present invention. is also used in a drying hopper with a dehumidifier.
The raw material moisture content is 0.05% or more when dried at 150℃ for 30 minutes. is vacuum extruded after vacuum drying at 150°C for 6 hours, and the raw material moisture content is 0.005%.
It is as below. There is a large difference in the intrinsic viscosity of the molded products (bands) formed depending on the raw material drying conditions described above. Even if raw materials with an intrinsic viscosity of 0.9 or less are used, the decrease in intrinsic viscosity can be suppressed by improving the drying conditions of the raw materials, and the physical properties are equivalent to those obtained by normal drying using raw materials with an intrinsic viscosity of 0.95 or higher. is obtained. Therefore, the quality of a molded article is affected not only by the intrinsic viscosity of the raw material but also by the intrinsic viscosity of the molded article. With normal raw material drying, it is unavoidable that the viscosity decreases by 8 to 10% during extrusion molding. However, as in the previous example, the raw materials are technically vacuum dried and vacuum extruded, which increases the drying time. Eliminate resin stagnation in the extruder cylinder and mold as much as possible. etc., it is possible to suppress the viscosity reduction to 5% or less. In the present invention, the intrinsic viscosity (IV value) of the raw material is
This is also the reason why polyethylene terephthalate resin with a molecular weight of 0.90 to 1.20 is used and the molded product is required to have an intrinsic viscosity (IV value) of 0.80 or more.

【table】

[Table] (Effects of the Invention) As described above, the present invention provides a distinctive packing band by using a high viscosity polyethylene terephthalate resin. The band of the present invention is most suitable for heavy-duty packaging. In particular, when packing heavy items using an automatic packing machine, its good heat-sealability improves work efficiency, and it can be left outdoors or in high-temperature locations for long periods of time. The band of the present invention has high tensile strength and heat sealing strength, does not crack vertically, has little aging (shrinkage) at high temperatures, has good weather resistance, and has industrial value due to its manufacturing method. It's expensive.

[Brief explanation of the drawing]

The drawings are schematic diagrams showing the manufacturing process of the method of the present invention. DESCRIPTION OF SYMBOLS 1...Hopper, 2...Extruder, 3...Mold, 4...First water tank, 5...First take-off machine, 6...Strip body, 7...First drawing tank, 8...Second take-off machine, 9...Second Stretching tank, 10
...Third take-up machine, 11... Emboss roll, 12... Heat treatment tank, 13... Second cooling tank, 14... Fourth take-up machine,
15... Band, 16... Winding device.

Claims (1)

[Scope of Claims] 1. A polyethylene terephthalate resin strip whose raw material has an intrinsic viscosity (IV value) of 0.90 to 1.20,
A packing band made of polyethylene terephthalate resin that is stretched in the length direction to have a total stretching ratio of 3 to 6 times. 2. A polyethylene terephthalate resin strip whose raw material has an inherent viscosity (IV value) of 0.90 to 1.20,
Packing made of polyethylene terephthalate resin, which is stretched in the length direction so that the total stretching ratio is 3 to 6 times, and furthermore, the molecular orientation arranged in the length direction over the entire range of the strip is disturbed by embossing. band. 3 A polyethylene terephthalate resin strip whose raw material has an intrinsic viscosity (IV value) of 0.90 to 1.20 and whose final molded product has an intrinsic viscosity (IV value) of 0.80 or more, which is stretched in the length direction to achieve a total stretching ratio of 0.90 to 1.20. A packing band made of polyethylene terephthalate resin that is 3 to 6 times larger. 4 Melt extrude polyethylene terephthalate with an intrinsic viscosity (IV value) of 0.90 to 1.20, dried in a drying hopper equipped with a dehumidifier of an extruder, from a mold, and cool the extruded molten resin in a first water tank to form a strip. ,
This strip-shaped body is stretched at a temperature of 85 to 100°C to a stretching ratio of 3 to 4.5 times as a first stage of stretching, and then stretched at a high temperature of 250 to 350°C as a second stage of stretching to fully stretch it in the length direction. The magnification is 4.6 to 6 times, and the temperature is 180 to
A method for manufacturing a packing band made of polyethylene terephthalate resin, which is heat-treated by passing it through a heat treatment tank at 280°C at a take-up speed with a down rate of 0 to 5%.