JPH05116214A - Production of low thermal shrinkable oriented tape made of polypropylene - Google Patents

Abstract

PURPOSE:To stably produce an oriented tape low in heat shrinkability having <=1% thermal shrinkage percentage by melting and extruding polypropylene having specified density, cooling and solidifying the extruded polypropylene and orienting it in the take-up direction of the tape and repeating retardant heat treatment therefor in the different conditions. CONSTITUTION:Polypropylene having >=0.9065g/cm<3> density is used, melted and extruded to obtain a film. This film is cooled, solidified and slit to form it into a tape-shape. This tape is oriented 3.5-7.5 times at 110-150 deg. in the take-up direction of the tape. Then retardant heat treatment of 5-12% is repeated at 130-150 deg. for the oriented tape. Furthermore retardant heat treatment of 4-10% is performed at higher temperature, namely 150-165 deg. for this oriented film. The oriented tape low in heat shrinkability having <=1% thermal shrinkage percentage at 150 deg. is stably produced by such treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polypropylene stretched tape used as a raw material for primary and secondary base fabrics used for carpets, artificial lawns, various mats and the like.

[0002]

2. Description of the Related Art Tufted carpets are produced by weaving stretched tape, laying pile threads on a primary base cloth, and then backing them with a hot melt backing material such as polyvinyl chloride, ethylene / vinyl acetate copolymer, polypropylene. Manufactured. At this time, the temperature at which the hot melt backing material is lined is at least 150 ° C, usually 160 to 180 ° C.
Therefore, there is a drawback in that the primary base cloth made of the conventional polypropylene stretched tape is heat-shrinked and the appearance of the carpet is impaired.

Therefore, it has been desired to develop a polypropylene stretch tape which does not shrink even at high temperatures. Japanese Patent Office Sho 62
JP-A-6011 discloses a method for producing a low-shrinkage polypropylene flat yarn (tape) having an average shrinkage rate of 0.3% or less at 130 ° C. for 10 minutes over the entire length.

The manufacturing method can be carried out by winding the flat yarn on a core tube with cheese and then leaving it in a thermostatic chamber in which hot air is circulated for a long time. In this case, considering the power cost, storage time, storage space, etc., it is inevitable in terms of cost. Further, as a result of additional tests conducted by us, the heat shrinkage rate at 150 ° C. for 10 minutes is 3 to 5%, which is not sufficient.

In Japanese Patent Publication No. 62-16172, a stretched polypropylene tape is heat treated with a multi-stage roll to obtain 13
A tape having a heat shrinkage of 0.4 to 0.6% when immersed in a silicone oil bath at 0 ° C for 10 minutes is disclosed. However, according to our additional test, the heat shrinkage at 150 ° C for 10 minutes is 4%.
It is ~ 6%, which is not sufficient.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a manufacturing method capable of stably producing a polypropylene stretched tape having a small heat shrinkage at a heat shrinkage of 1% or less at 150 ° C.

[0007]

[Means for Solving the Problems]

[0008]

The present invention has a density of 0.9065 g / cm.
It is intended to provide a method for producing a low heat-shrinkable stretched tape through the following steps using ³ or more polypropylenes. (1) Polypropylene is melt extruded to obtain a film. (2) The film is cooled and solidified and slit into a tape. (3) The tape is stretched 3.5 to 7.5 times at a temperature of 110 to 150 ° C. in the tape taking direction. (4) The stretched tape should be 5
A relaxation heat treatment of 5 to 12% is performed at a temperature of 130 to 155 ° C, which is higher by -40 ° C. (5) This stretched tape is at a temperature 10 to 35 ° C. higher than the relaxation heat treatment temperature of (4) above, and is 150 to 165.
A relaxation heat treatment of 4 to 10% is performed at a temperature of ° C.

(Polypropylene) The polypropylene used in the present invention is most preferably a homopolymer of polypropylene, but is a copolymer of polypropylene and ethylene, butene-1, etc. within a range not impairing the physical properties of the flat yarn, And mixtures thereof. And the density of this polypropylene (JIS K-7112)
Is 0.9065 g / cm ³ or more, preferably 0.9070 g / cm ^{3 to} 0.9095 g / cm ³ . If the density is less than 0.9065 g / cm ³ , the target low heat-shrinkable stretched tape cannot be obtained.

(Manufacturing Process) The stretched tape of low heat-shrinkable polypropylene of the present invention is manufactured through the following processes (1) to (5). (1) Polypropylene is melt extruded to obtain a film. (2) The film is cooled and solidified and slit into a tape. (3) The tape is stretched 3.5 to 7.5 times at a temperature of 110 to 150 ° C. in the tape taking direction. (4) The stretched tape should be 5
A relaxation heat treatment of 5 to 12% is performed at a temperature of 130 to 155 ° C, which is higher by -40 ° C. (5) This stretched tape is at a temperature 10 to 35 ° C. higher than the relaxation heat treatment temperature of (4) above, and is 150 to 165.
A relaxation heat treatment of 4 to 10% is performed at a temperature of ° C.

In the present invention, the above polypropylene is melt-kneaded by adding a heat stabilizer, a light stabilizer, a lubricant, a flame retardant, an antibacterial agent, a pigment, an inorganic filler and its dispersant, etc., if necessary. Then, polypropylene is melt-extruded into a film at a extrusion temperature of 210 to 250 ° C. and cooled (20 to 10) by a method using a known T-die, circular die, or the like.
(0 ° C.) solidifies to form a film having a wall thickness of 20 μm to 250 μm.

A predetermined width (1 to 100 mm) of the film
The tape is cut into a tape shape, and the first-stage drawing is carried out by a known method using an oven, a roll, a hot plate or the like at a temperature of 110 to 150 ° C. and a drawing direction of 3.5 to 7.5 times. If the stretching temperature is less than 110 ° C., the stretching stress is large, and even if a relaxation heat treatment is performed after stretching, the residual stress cannot be removed and the target low heat-shrinkable stretched tape cannot be obtained. On the other hand, if the stretching temperature exceeds 150 ° C., the stretched tape floats to cause entanglement, or the tapes stick to each other, or the tape adheres to a hot plate or the like to cause stretch breakage.

If the stretching ratio is less than 3.5 times, uneven stretching occurs and the width fluctuation of the stretched tape is not reduced, which makes quality and stable production difficult. On the other hand, if the stretching ratio exceeds 7.5 times, it becomes a highly oriented stretched tape, and even if a relaxation heat treatment is applied, residual stress cannot be completely removed and the target low heat shrinkable stretched tape cannot be obtained. The stretching at 110 to 150 ° C. may be performed once or twice or more. However, if you do it more than once,
It is necessary to limit the stretching ratio after stretching to 7.5 times or less of the original film original.

In the present invention, it is necessary to perform the relaxation heat treatment in two or more steps in the tape take-out direction. This is because it is not possible to produce a target stretch tape having a low heat shrinkability by a relaxation heat treatment of the tape in only one step. The relaxation heat treatment of the stretched tape in the first step is performed, for example, using an oven of a hot air circulation system so that the relaxation rate becomes 5 to 12% at a temperature of 130 to 155 ° C. And relaxation rate, when the peripheral velocity of the two rolls taking up the stretched tape was v _1, v _2, the following formula (I) relaxation rate _{= 100 (v 1 -v 2)} / v 1 ··· (I ) Is calculated as Therefore, the relaxation rate is usually 5 to 12%.
However, the stretched tape is taken out by rotating the roll at a peripheral velocity of the latter roll which is 1.05 to 1.12 times the peripheral velocity of the former roll. The relaxation heat treatment of the second-stage stretched tape uses a heat-circulation type oven at 150 to 165 ° C.
At a temperature of 4 to 10%.

When the temperature of the relaxation heat treatment in the first step is lower than 130 ° C, a low heat-shrinkable stretched tape cannot be obtained, while at 155 ° C.
If it exceeds, the stretched tapes will stick to each other and it will be impossible to stably wind the stretched tape. Also, the relaxation rate is 5%
If it is less than 1, the residual stress remains in the stretched tape, and it cannot be a low heat-shrinkable stretched tape (the heat shrinkage ratio at 150 ° C. is 1% or less). On the other hand, when the relaxation rate exceeds 12%, the stretched tape floats as the relaxation rate increases, and the stretched tapes are entangled with each other, which makes it difficult to stably produce the stretched tape.

If the second stage relaxation heat treatment temperature is less than 150 ° C., a sufficient relaxation rate cannot be obtained and a low heat shrinkable stretched tape cannot be obtained. Further, when the temperature exceeds 165 ° C, the stretched tapes are fused with each other, which makes it difficult to perform stable production. or,
If the relaxation rate is less than 4%, residual stress remains in the stretched tape and the low heat shrinkable stretched tape cannot be obtained. On the other hand, if it exceeds 10%, the stretched tape floats and the stretched tapes are entangled with each other, so that it becomes difficult to stably produce the stretched tape.

The temperature of the relaxation heat treatment in the first step is 5 to 40 ° C. higher than the temperature at the time of stretching the tape, preferably 10
Perform at ~ 30 ° C higher temperature. The temperature of the second relaxation heat treatment is higher than the temperature of the first relaxation heat treatment by 5 ° C. or more, preferably 10 to 30 ° C. higher. If the temperature is not raised in this way, a stretch tape with low heat shrinkability cannot be obtained. All of these temperatures are lower than the melting point of polypropylene (the temperature at the higher skirt of the peak of the DSC curve). The stretched tape obtained by the present invention has a width of 0.5 to 50 mm and a wall thickness of 10 to 100.
μm.

[0018]

【Example】

Examples 1 to 3 and Comparative Examples 1 to 8 A homopolymer of polypropylene having a melt flow rate of 2 g / 10 minutes and a melting point of 172 ° C. is melt extruded into a film with a T die using an extruder of 65 mmΦ, and 20 m / min. After being cooled and solidified while being drawn at a speed to form a polypropylene film, the polypropylene film was cut into tapes, and drawn by a hot plate drawing method in the drawing direction at a temperature shown in Table 1 to a draw ratio shown in the same table.

Then, a relaxation heat treatment of the first step, the second step, or a relaxation heat treatment of only the first step was performed in an oven of a hot air circulation system to manufacture a polypropylene stretched tape of 1200 dale. The density, extrusion temperature, stretching temperature, stretching ratio, thermal relaxation treatment temperature, and relaxation rate of the polypropylene used were as shown in Table 1. Table 1 shows the measurement results of the tensile strength, the tensile elongation, and the heat shrinkage rate of the obtained flat yarn.

Here, the tensile strength and the tensile elongation are JIS
The thermal shrinkage was measured by L-1070, and the thermal shrinkage was measured after being immersed in a silicon oil bath at 150 ° C. for 10 minutes.

[0021]

[Table 1]

[0022]

EFFECT OF THE INVENTION In the method for producing a stretched polypropylene tape of the present invention, a polypropylene having the above-mentioned constitution and having a density in a specific range is used, stretched, and then the stretched tape is subjected to a relaxation heat treatment in multiple stages to reduce the heat treatment. It becomes a shrinkable stretched tape, and it is possible to stably produce stretched tape without forming troubles of stretch breakage, fusion of stretched tapes during relaxation heat treatment, winding troubles due to floating, etc. .

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display area B29L 7:00 4F

Claims (1)

[Claims] 1. A method for producing a polypropylene low heat-shrinkable stretched tape through the following steps using polypropylene having a density of 0.9065 g / cm ³ or more. (1) Polypropylene is melt extruded to obtain a film. (2) The film is cooled and solidified and slit into a tape. (3) The tape is stretched 3.5 to 7.5 times at a temperature of 110 to 150 ° C. in the tape taking direction. (4) The stretched tape should be 5
A relaxation heat treatment of 5 to 12% is performed at a temperature of 130 to 155 ° C, which is higher by -40 ° C. (5) This stretched tape is at a temperature 10 to 35 ° C. higher than the relaxation heat treatment temperature of (4) above, and is 150 to 165.
A relaxation heat treatment of 4 to 10% is performed at a temperature of ° C.