JPS59130338A - High elasticity and high strength fiber or film and production thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing high modulus, high strength fibers or films.

In recent years, various demands for high elasticity and high strength fibers or films have been high, and in particular, research and development regarding their production methods has been actively conducted.

For example, the method disclosed in Japanese Unexamined Patent Publication No. 15430/1984 is one of the representative methods. Highly oriented elongation can be achieved by zone stretching in the lower limit of the temperature range, that is, in principle, by hot stretching a limited portion of the fibril to be drawn in a narrow area where a heater and cooler are installed and immediately cooling it. This method forms a chain structure, and as a result, highly elastic and highly strengthened fibers or films can be obtained.

This method has the advantage that the above-mentioned high modulus high strength fibers or films that generally require complicated spinning and drawing can be significantly simplified.

Therefore, to explain this method in more detail, the method actually:
By repeating the above zone stretching in multiple stages, the polymer chains of the fibril are gradually disentangled and aligned in the longitudinal direction in order to achieve the high elasticity and high strength mentioned above. The fiber to be drawn is heated only at the waist portion during the drawing, and a substantially uniform force is applied to all the polymer chains in this portion, so that it can be expected that the fiber will be drawn in an approximately ideal state.

As mentioned above, an important feature of this method is that the width of the heating zone during zone stretching is small; that is, since hot stretching is performed in a very small area, stretching unevenness of individual fibers occurs. The orientation is extremely small and the orientation is extremely high.

Generally, it is said that the width of the above-mentioned heating region is 10 mm or less, preferably 2 ttrrn or less, and most preferably about 100 μm or less, which is close to the length of the microfibrils in the fibers to be drawn. Since the cooling after stretching freezes the highly oriented orientation structure of the object to be stretched as described above, it is required that the temperature gradient be sharp.

However, as a heating and cooling means for highly assimilating polymer fibrils through hot drawing, in reality, it is common to use an electric heater as the heat source and cold water as the cooling medium. has its own limits.

Measures are taken to install a smoother to prevent heat diffusion in the heating and cooling sections, but this also causes a slowing of the temperature gradient. It is the cause.

In view of the current situation, the inventors have conducted intensive machining and have found that, in the above-mentioned zone stretching, the phenomenon of heat generation or heat absorption during energization at the contact surface of dissimilar metals, that is, the Beltier effect, is utilized as a means of heating and cooling. The inventors have found that the above-mentioned problems can be surprisingly solved by doing so, and have arrived at the present invention.

That is, this invention provides a method for producing highly oriented fibers or films by zone-stretching amorphous or as low-crystallinity fibrils or films at a temperature above the glass transition point and below the crystallization temperature. and a method for producing a highly elastic and highly strong fiber or film, characterized in that the Beltier effect, which causes heat generation and heat absorption when electricity is applied through the contact surfaces of dissimilar metals, is utilized as a cooling means.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 schematically shows the above-mentioned heated stretching section in the apparatus for implementing the method of the present invention, in which a bonded body 2 of dissimilar metals 2a and 2b is arranged on both sides of an object 1 to be stretched, such as a raw fiber. It is. 3 is a circuit for passing current between these dissimilar metals 2a and 2b.

When a current flows through the contact surface between the metals 2a12b, heat generation or heat absorption occurs as the Beltier effect depending on the direction of the current.

Metals with different electrical conductivities are used as a combination of different metals, but the most common are calomel and allomel.
Other examples include copper and constantan, or platinum and platinum lotum.

Since the heat generation and heat absorption occur at the joint surfaces of the dissimilar metals, the temperature gradient at that portion is very steep. For example, the temperature change with voltage change in the case of using calomel and allomel is shown in FIG. 2, and an example of the temperature gradient when these exothermic and endothermic phenomena are utilized is shown in FIG. 3. The steepness of the gradient is clear compared to FIG. 4, which shows an example of a conventional temperature gradient using an electric heater.

In the present invention as well, the object to be drawn must be drawn under uniform tension at a temperature above the glass transition point and above the crystallization temperature of the polymer used for the fibrils. In particular, it is desirable to set the stretching speed, combination of metals, appropriate current value, etc. such that a heat generation amount that can reach the lower limit temperature in the crystallization temperature range is obtained.

The fibrils or raw films used in this invention include:
Amorphous fibers or films that do not contain existing crystals, such as lamellae, are preferred, but if these are not available, low-crystalline, low-orientation fibers or films may also be used.

Specific examples of the degree of orientation and degree of crystallinity of such fibrils or films are as follows.

Birefringence Crystallinity (9)) Polyethylene 0.5X10 or less 6
0 or less polyethylene terephthalate 0.3X10 1
/ 2.0 nylon 6 35.0X1
0 // 30 // In addition, crystalline polymers such as polypropylene may be used.

The present invention will be specifically described below with reference to Examples.

Example 1 Sail obtained by rapid cooling after melt spinning, 5 φ, birefringence 0.5×10
, high-density polyethylene fibrils with a crystallinity of 55% were first
Using a zone stretching apparatus equipped with heating and cooling sections as shown in the figure, stretching was carried out under the following conditions as in the conventional method.

Stretching temperature 90℃ Tension 3/crI Cooling temperature
-40°C Stretching area setting width 2wn Note that the different metals in the heating and cooling section were a combination of calomel and allomel, and a DC voltage of 2.43 mV was applied.

The properties of the obtained stretched product were investigated and the results are shown in Table 1. For comparison, the same procedure was carried out except that a heating heater was used for the heating described above, and the results are shown in the same table.

Table 1 According to the results shown in Table 1 above, it is clear that the present invention exhibits superior effects compared to those using electric heating.

Example 2 In place of the polyethylene in Example 1, the following polyethylene terephthalate and nylon 6 fibrils were used as shown in Tables 2 and 3 below.
The test was carried out in exactly the same manner except that the conditions shown in 1 were used, and the results are shown in the same table.

Polyethylene terephthalate 2. lX10100.
3X10-31.8 Nylon 6 7X10'°
35.0X10-319 According to the results in Tables 2 and 3, it was clear that the present invention was very effective for fibrils made of polyethylene terephthalate and nylon 6 in addition to polyethylene.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of the heated stretching section in one embodiment of the apparatus for carrying out the present invention, Fig. 2 is a Peltier effect diagram when calomel and allomel are used, and Fig. 3 is a temperature diagram due to the same effect. An example of the gradient, FIG. 4, is a diagram similar to FIG. 3 when an electric heater is used. ■...Object to be stretched, 2a r 2b...Different metal, 2
...Metal joint. Patent applicant Mitsubishi Rayon Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] When manufacturing a highly oriented fiber or film by zone stretching an amorphous or as low crystallinity fibril or film at a temperature above the glass transition point and below the crystallization temperature, as a heating and cooling means in the zone stretching, A method for producing a highly elastic and highly strong fiber or film, characterized by utilizing the Peltier effect that generates heat and absorption when electricity is passed through the contact surfaces of dissimilar metals,