JPS6059113A - Polypropylene fiber with improved thermal shrinkage and strength - Google Patents

Abstract

PURPOSE:A polypropylene fiber that is composed of a polypropylene of a specific density and pentad fraction, thus having improved strength and heat shrinkage under a heated atmosphere and increasing quality retention of the products therefrom and productivity. CONSTITUTION:The objective fiber is composed of a polypropylene resin which has a density of more than 0.905, preferably more than 0.910, an isotactic pentad fraction (P0) in the insoluble part in boiling n-heptane of more than 0.960 and pentad fraction with different configurations (P2) of less than 0.002 (0.2%).

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to propylene fibers, and more particularly to polypropylene fibers manufactured from a specific polypropylene resin and having improved strength and shrinkability in a heated atmosphere.

Generally, fibers made of polypropylene resin (hereinafter referred to as "PPJ and road use") are made into stable or filament shapes, and are further processed into futon cotton, carpet pile, non-woven fabrics, industrial materials, and knitted fabrics through various secondary processes. It is commercialized and used in textiles and cloth-like materials.

By the way, fibers made of PP have appropriate strength characteristics due to oriented crystallization during spinning and drawing processes and are used in practical applications, but they have the disadvantage that they tend to deteriorate in strength and shrink due to aging or thermal conditions. There is.

Therefore, in order to prevent shrinkage over time at room temperature during product storage or practical use, a relaxing heat treatment is performed at a temperature below the melting point of PP after stretching, and during orientation during spinning and stretching, which is one of the causes of shrinkage. It is usual to stabilize the shrinkage by removing the generated internal strain or residual stress and promoting recrystallization.

On the other hand, turning fiber into a product requires various secondary processing steps, and depending on the product, there are many steps in which the product is exposed to a hot atmosphere at a temperature higher than room temperature. A return to the time orientation occurs and the contraction increases rapidly.

For example, in the case of tact carpet, the base fabric is tufted with PP fiber as pile yarn and lined with latex, and then the latex goes through a drying process, so it is exposed to a very high temperature atmosphere. The high temperature and speed of drying the 1' culm are significantly increased in order to improve the properties of carpets, resulting in further decreases in strength and shrinkage, resulting in shrinkage and decreases in strength of the tufted fibers, leading to a deterioration in the quality of the carpet.

Therefore, the present inventors carried out intensive testing to improve the strength and heat shrinkability of fibers obtained by ordinary spinning and drawing, and found that the density was 0.905 or more, and the isotactic content of the boiling n-hebutane insoluble portion was From K, using PP as a material with a tick fraction (Po) of 0960 or more and a pentad fraction (P,) having two different configurations of 0.002 (0.2%) or less The inventors have discovered that the strength of the fibers can be improved and that the heat shrinkability, particularly at high temperatures, can be improved to 1 J, resulting in the present invention.

The PP used in the present invention can be produced by the method described in Japanese Patent Application No. 56-204066. That is, the solid product (1) obtained by reacting an organoaluminum compound or a reaction product of an organoaluminum compound and an electron donor with titanium tetrachloride is further reacted with an electron donor and an electron acceptor. The solid product ([1) obtained by
1) by polymerizing propylene in the presence of a polymer with a molar ratio I11/II=0.2 to 100.
It will be done.

Isotactic pentad fraction, A*Zayrt
bell: Macromolecules by etc.
It is the isotactic fraction in pentad units in a polypropylene molecular chain measured using the method published in 925 (1973), that is, I" O-NMIL. Therefore, isotactic pen What is Tad fraction?
Propylene monomer 1i is the fraction of globile monomer units in which five consecutive isotactic bonds are formed at the 1st position. The peak attribution method in the above NVR measurement is 1'14. acromolecules, 687 (
(1975). Incidentally, NM in the embodiment described above
Measurement by R [HaF'l'-NMR) 270MI (Z)
After 27,000 integrated measurements, the signal detection limit was determined by the isotactic pentad fraction.
, I made white clay up to o o i.

Regarding pentads, ■ Isotactic pentads are mmmm (OO'Q 00 ) or (1111
1), and a pentad with one different configuration is mmmr (oooooi) or (1
1110), mmrr(00010) young 1. < is (1
1101), m y y y21 (o o 1o o
) or (11011). Furthermore, ■ Pentad has a different configuration of 2' WR! Old 11 r In (00011) or (11100), mrrr (00101) or (
11010), III r m r (00110) or (11001), rrmr (01001) or (10110), rrrr (01010) or (1
0101), rlnnlr (01110) or (1
0001) etc. Here, m stands for isotactic diamond, r stands for sysidiotactic diamond, 0°1 stands for the configuration of individual monomer coronation along the polymer chain, and 0 stands for stone, Ruichi. 117 (0) Opposite 0) configuration -4゜Polypropylene used in the present invention i%n-heptane insoluble matter
Kosai 1 was completely dissolved in boiling xylene, poured into 5 tons of methanol to precipitate, recovered and dried, and then Soxhlet extracted with boiling n-hebutane for 6 hours. Density was determined by JISK 6758 press method.
1 was prepared and measured by the underwater displacement method of JIS K 7112.

The isotactic pentad fraction (Po) of the n-hebutane-insoluble part of boiling vinegar is g, 96 LI K, fg4 tal (1'1'), which improves strength and heat shrinkage.
4j is the oldest child]. Further, the density of the raw material PF which is not subjected to any treatment such as extraction is preferably 0.905 or higher, more preferably Q910 or higher, and if it is less than this, the effect of improving heat shrinkage is insufficient. Furthermore, the pentad fraction (P,) that has two N-species configurations
If it exceeds 0.002, the effect of improving heat shrinkage is insufficient.

The PP used in the present invention has a melting point 2C or more higher than ordinary PP and has a very high degree of crystallinity.

This is shown, for example, by D8C (differential scanning calorimetry) measurements. Furthermore, the crystallization rate from the molten state is faster than that of conventional ones, and the growth rate of spherulites and the number of spherulite nuclei generated are also higher. As mentioned above, it is believed that the reason for the improvement in strength and heat shrinkability of the present invention is that the crystallinity is higher and the crystallization rate is significantly faster than that of conventional PP.

In the present invention, Pl)Nll fibers refer to stable filaments obtained by melt-spinning PP, irregular cross-section yarns, tows,
A general term for drawn yarn, undrawn yarn, heat treatment system, and secondary processed products thereof.

When making a mat using the PP of the present invention, known methods such as spinning, stretching, heat treatment, etc. and binding may be used.

The present invention will be explained below with reference to Examples and Comparative Examples.

Example-1 and Comparative Example-1 MFR is 5.0, density is 0.911, isotactic pentad content of boiling T1-hebutane insoluble portion '+? (1'
. ) is 0.960, PP with a pentad fraction (P, ) smaller than o, o02 having a different configuration of 2 digits is granulated by adding stabilizers and additives, and the pellet is granulated using an extruder with a diameter of 40 fins. After obtaining an undrawn yarn with a fineness of 15 d/f using a nozzle with a nozzle diameter of 0.5 and 150 holes, it was drawn at various magnifications using an ordinary drawing machine, and then the surface temperature was 1.
3. Perform 5% relaxation heat treatment while heating on a 30C hot plate.
Table 1 shows the results of measuring the strength and heat shrinkage of fibers of ~6d.

At the same time, as comparative examples, PF has an MFR of 4.8, a density of 0900 boiling points, an isotactic pentad fraction (Po) of the Rn-hebutane insoluble part of 1), 935,
Comparative Example 1 shows the characteristic values of a fiber obtained in the same manner as in Example 1 using pellets granulated with the same stabilizers and additives as in Example 1. Further, the results in Table 1 are shown in FIGS. 1 and 2. In the figure, 1 indicates each case of Example 1.2 and Comparative Example 1 (both drawing ratios are 6 times).1゜From Table 1 and Figure 1.2, the fibers according to the present invention shrink when heated compared to the comparative example. As the shrinkage ratio becomes smaller and the temperature becomes higher, a remarkable difference in heat shrinkage is observed, and an improvement in strength is also observed.

Implementation fI, l-2, 3, Comparative Examples-2, 3, 4 Example-1
Stretching ratio 6 when only the raw materials are changed under the same manufacturing conditions as
Table 2 shows the properties of heat shrinkage and strength at 100% strength.

From Table 2, PP whose density is less than 0.905, Po is 0
Fibers made from PP with less than 960 or PP with P greater than 0.002 both have a large heat shrinkage rate.
In addition, it is clear that the fibers according to the present invention have a low heat shrinkage rate and an improved strength, whereas the fibers have a low strength.

The fiber according to the present invention has greatly improved heat shrinkage rate and also has improved strength, and the heat shrinkage is particularly effective in high temperature atmospheres, so when a drying process is required for carpets etc. It is easy to respond to the trend of high temperature and high speed, and has advantages in terms of maintaining product quality and high productivity.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the heat shrinkage rate under various temperatures of the drawn yarn obtained in Example 1 and Comparative Example 1, and Fig. 2 is a graph showing the drawn yarn obtained in Example 1 and Comparative Example 1. It is a figure showing the relationship between magnification and intensity. In these figures, 1 indicates Example 1, and 2 indicates Comparative Example 1 (both at a stretching ratio of 6 times). that's all

Claims (1)

[Claims] The density is 0905 or more, the isotactic pentad fraction (PO) of the boiling n-Heflin insoluble part is 0.960 or more, and the pentad fraction (Pt) with two different configurations is 0.002 or less Polypropylene fibers with improved heat shrinkability and strength, made from polypropylene resin, f, Il.