JPS62133106A - Highly elastic yarn - Google Patents

Abstract

PURPOSE:The titled yarn having extremely improved mechanical characteristics, obtained by drawing the minimum part of undrawn yarn consisting of a high- density PE resin which has molecular weight in a specific range and narrow molecular weight distribution under heating under stretching. CONSTITUTION:Undrawn yarn consisting of a high-density PE resin having molecular weight Mw of 140,000-200,000, molecular weight distribution Mw/Mn of 3-5 and density of preferably 0.94-0.97 is subjected to zone drawing to draw its minimum part under heating under stretching to give the aimed yarn having modulus of elasticity of 100-250GPa. The zone drawing, for example, is carried out by heating the undrawn yarn 3 stretched between rolls 1 and 2 by a minimum band heater 4 (e.g., having 2mm width) at 100-130 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to fibers with excellent mechanical properties, and in particular, the raw fibers are made of a specific resin.

The present invention relates to synthetic resin fibers that are useful in fields that require excellent mechanical properties, such as a high I modulus obtained by zone heating drawing of the fibers.

(Prior Art) In recent years, research has been conducted to produce highly elastic and highly viscous fibers from flexible polymers.Such fibers are used in fields that require excellent mechanical properties, such as golf equipment. useful in the field.

Such manufacturing techniques include high-pressure extrusion [for example, Journal of Polymer Science, Polymer Physics Edition (J@Polym.

Sci, Polym, Phys, Ed)
635 (1974)], Gui stretching [e.g., Journal of Polymer Engineering Science (J*Of e Polymer Eng., Sci.
20.

1229 (1981)], gel spinning [e.g.
Smook and A, J, Penn1
g5. Polymer◆Bul! , 9.75 (198
3) 1. Melt spinning at high speed [e.g.
33. T-208 (1977), zone φ stretching heat treatment [e.g., Journal of Applied φ Polymers
Scien 7, (J a Polym, Sci,)
V.

Bun, 26, 1951-1960 (1981), Journal of the Fiber Science Society Vol. 1.40. No. 9 (1984), Special Publication Showa 60
-24852].

However, in the methods of high-pressure extrusion and Gui stretching, the tensile force is very small and auxiliary compared to the high pressure applied to the raw material side. Therefore, there is a risk that the molecular chains will become stuck in the form of threads near the cap, and it is not easy to orient the molecular chains.

In addition, the method using gel spinning uses an organic solvent in the melting process, making it very expensive.Also, since it uses a large amount of organic solvent, there are still problems with post-processing, and there is a high possibility of mass production through industrialization. However, the elastic modulus of the obtained fibers is only about 40 to 60 GPa at most.

Furthermore, in the high-speed melt spinning method, the unfolding of molecular chains is promoted by means such as high speed and freezing, so the resulting fibers cannot form a stable crystalline structure and tend to have an amorphous structure. There are some difficulties.

Furthermore, in the conventional zone drawing and heat treatment method, Japanese Patent Publication No. 60-24852 discloses that high elasticity and high strength fibers are produced by zone drawing and zone heat treatment of amorphous or as low crystalline raw fibers as possible. However, this method requires heat treatment after stretching and involves two operations, and the obtained tb't
The gt glue i property remains low, and the conventional zone stretching and heat treatment methods, including those published in the above-mentioned journal of the Japan Institute of Textile Science and Technology, are originally experimental methods and have not been implemented continuously on an industrial scale. In addition, since the fibrils are stretched by applying a constant load, there are problems such as variations in the stretched material due to non-uniform applied stress due to non-uniformity of the cross-sectional area of the fibrils, and fibril breakage during stretching. As described above, conventional methods have many problems with industrialization and product quality, such as problems with molecular orientation, and are also extremely expensive, making industrialization unrealistic. However, the current situation is that this objective has not been fully achieved.

[Problems to be Solved by the Invention] In view of the above circumstances, an object of the present invention is to eliminate the drawbacks of the prior art and provide a fiber having excellent mechanical properties.

Another object of the present invention is to obtain synthetic resin fibers useful in fields requiring excellent mechanical properties on an industrial scale using an a-sequential process.

(Means for Solving the Problems 1) The present invention is a fiber made by heating and stretching the smallest part of a fibril under tension.
It is made of high-density polyethylene resin with a molecular weight distribution Mv/Mn of 3 to 5, and has a fiber elastic modulus of 100 to 250 GPa, high elasticity and high strength t, and 11 fibers.

The present invention will be explained in detail below.

The fibril used in the present invention is unoriented amorphous 48
m is preferred, but those with low crystallinity and low orientation can also be used.

Regarding the physical properties of the high-density polyethylene resin for the fibrils, a resin with a narrow molecular weight distribution of a molecular iMw of 140,000 to 200,000 and a molecular weight distribution Mw/Mn of 3 to 5 is used. The density of the resin is preferably 0.94 to 0.97.

As a result of intensive studies by the present inventors, resins with such physical properties are optimal for zone stretching, particularly in the minimal area heating stretching method based on intensive studies by the present inventors, which will be described later. It has been found that extended chain crystals can be formed without difficulty.

Such fibrils are subjected to zone drawing.

Zone drawing is carried out by heating and drawing the smallest portion of the fibril under tension.

Next, a preferred method of zone stretching (minimum area heating stretching method)
will be explained together with its device.

In this method, the fibril is stretched between rolls at a constant speed.

An outline of the apparatus is illustrated in FIG. This is caused by the difference in rotational speed between the delivery roll 1 and the take-up roll 2, and allows the fibril to be drawn continuously.

The delivery roll 1 and the take-up roll 2 are operated by a motor (
(not shown), the fibril 3 is stretched at a constant magnification, and tension is applied to the fibril. At this time, the delivery speed by the delivery roll 1 is V c (ff1m/min), and the winding speed by the 1 take-up roll 2 is V D (a
m/min), the draw ratio for the fibril is given by a linear equation by simple calculation.

Therefore, from the above, by appropriately selecting VD with respect to Vc, a sample with an arbitrary stretching ratio can be produced.

It is preferable that the value is 15.

An extremely small band heater 4 is installed between the rolls 1 and 2 of the fibril 3, which is continuously tensioned between the rolls, to heat the extremely small part in the crystal dispersion temperature range. In addition, in Figure 1, 5
and 6 are guide rolls.

The extremely small band heater 4 is configured to have a width of 2 mm, for example. Other heating means may also be used.

In the above case, in order to prevent heat dispersion in the heating section 4,
Cooling units 7 are installed on both sides of the heating unit 4. These outlines are enlarged and shown in FIG. This cooling section 7 injects vaporized cold air 8 of a cooling medium such as liquid nitrogen into the inside of the cooling section 7 and discharges it to the opposite side from the micro band heater 4, thereby minimizing heat dispersion from the heating section. This makes it possible to concentrate the applied stress at one point on the minimal heating section 4. The heating temperature (stretching temperature) for the fibrils is preferably about 100 to 130°C.

The cooling temperature in the cooling section 7 can be adjusted by the amount of vaporized cold air 8 injected from liquid nitrogen.

The cooling temperature is preferably 0° C. or lower in consideration of the need to prevent relaxation of molecular weight unfolding.

Note that the above-mentioned apparatus used for continuous minimization, small area heating and stretching can be similarly applied to a vertical apparatus.

The results showed that the fibers produced continuously by the above-mentioned production method have very remarkable molecular structure and mechanical properties.

The elastic modulus of the fibers of the present invention is significantly improved compared to gel-spun fibers and conventional zone-stretched/heat-treated fibers.
It showed ~250 GPa.

[Example] Next, examples of the present invention will be shown.

In addition, the measuring method of mechanical properties etc. in an Example is shown next.

(1) Measurement of tensile modulus of elasticity and breaking strength Measurement of tensile modulus of elasticity E and breaking strength was carried out under the following Tensilon conditions.

Sample length: 20 mm Crosshead pulling speed: 20 mm/min A linear photosensor was used to measure the cross-sectional area of the sample.

A minimum of five layers were measured using an electronic thickness gauge, and the average was taken. Note that the breaking strength σb is likely to be smaller than the actual value due to large errors due to chaff breakage, so it should be used as a reference only. The elastic modulus E was calculated from the initial slope of the stress-strain curve obtained from the tensile test.

(2) Density measurement Density measurement is performed at 25°C using a water-methanol density gradient, etc.
It was measured by the float-sink method. At this time, the sample is made into several knots, and bubbles are almost completely removed using an aspirator in a water-methanol mixed solution over a period of about 5 to 20 minutes, and then the sample is placed into a gradient tube for measurement. I did it.

The crystallinity Xc was determined from the measured density by the following calculation. The crystalline and amorphous densities of polyethylene are respectively , /
'C=1.000. = 0.852(3)D S
C measurement DSC measurement is done using Daini Seikodai's 5SC1560S yste.
Using m, put 1 g of samples 4 to 9II into an aluminum pan and heat to 75°C-17 at a heating rate of 20°C/min.
I11 was determined over a temperature range up to 5°C. The reference material is indium, whose melting point is 156.6°C1 melting 7%.
It was calibrated as ΔH+nd=13.79/g.

In addition, the heat of fusion is calculated using the microcomputer APPLE.
] [Calculated by determining the area of the peak using a Graph Ink doublet system digitizer.

Crystallinity Xc determined by DSC measurement (4) Birefringence measurement The birefringence of the sample was measured using a polarizing microscope equipped with a compensator using sodium as a light source. At this time, since the sample was thick, there would be a large number of interference fringes, so the sample was cut diagonally with a sharp knife and the cross section was observed with a polarizing microscope to measure birefringence.

Example 1 and Comparative Examples 1 to 4 Minimal area heating stretching was carried out using the apparatus shown in FIG.

As the fibrils, several types of high-density polyethylene fibers having a diameter of about 0.6 mm and having different physical properties in the as-spun state were used. The heating temperature was 120°C, and the fiber drawing was
20 (times). Original m M was stretched smoothly with some necking.

The results are shown in Table 1.

Table 1 Hereinafter, the physical property values of the sample are shown.

In sample No. 35, the maximum stretching ratio, birefringence, and crystallinity are the highest, and accordingly, the elastic modulus and breaking strength are the highest. Fibrils or high-density polyethylene having an Mw/Mn value of 3 to 5 are considered to be optimal.

In addition, for the value of Mn, 150,000 shows the maximum value for both elastic modulus and breaking strength, and if tα is suitable, +1! ,n be defeated.

This is the value of normal high-density polyethylene, and ultra-high molecular weight polyethylene is: (Sample E, which is unsuitable for stretching, is a sample obtained by gel spinning of ultra-high molecular weight polyethylene.

Example 2゜Stretching ratio (on), stretching temperature, winding roll speed (V
D) The same procedure as in Example 1 was carried out except that the shortest part was heated and stretched.

Dynamic elastic modulus E', E measured at room temperature under each stretching condition
Figures 3 and 4 are diagrams in which ' is plotted against the stretching conditions, respectively. Storage modulus E at room temperature shown in Figure 3
' corresponds to the tensile force E obtained from the initial slope of the stress-strain curve due to Tensilon.

In particular, in Figures 3 and 4, both elastic moduli E and E at room temperature
It can be seen that the stretching temperature has a peak around 110°C to 120°C for each stretching ratio. FIG. 5 shows a plot of the tensile modulus E determined from the initial slope of the stress-strain curve obtained by the Tensilon tensile test for each stretching condition.

The fist movements for each stretching condition with a tensile modulus E shown in FIG. 2 around the temperature
The elastic modulus of the sample stretched 0 times is about 152 GPa, which is a fairly high value as a tensile elastic modulus.

[Effects of the Invention] According to the present invention, synthetic resin fibers with extremely excellent mechanical properties can be obtained, and their industrial value is extremely high.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of an example of a manufacturing apparatus used in the present invention, FIG. 2 is an enlarged partial explanatory diagram of the same, and FIGS. 3 to 5 are graphs showing the results of examples of the present invention. l... Supply roll 2... Take-up roll 3... Raw fiber 4... Heating section (miniature band heater) 7... Cooling section Patent applicant Ryo Sato, patent attorney for Showa Denko K.K. Figure 3 Grape Ishin 9L/l ('(1) Figure 4 90 100 110 /2o t3o RL
0)
C)

Claims (1)

[Scope of Claims] A fiber made by heating and stretching the smallest part of a fibril under tension, the fibril being made of a high-density polyethylene resin with a molecular weight Mw of 140,000 to 200,000 and a molecular weight distribution Mw/Mn of 3 to 5, Highly elastic, high-strength fiber with an elastic modulus of 100 to 250 GPa.