JPH06248513A - Low-creeping fiber and its production - Google Patents

Abstract

PURPOSE:To obtain a polyamide fiber having excellent creep characteristics and exhibiting little lowering of stress by water-absorption and a process for producing the fiber. CONSTITUTION:The polyamide fiber has a creep characteristic of <=35% and is composed of a resin composition containing a polypropylene resin and a polyamide resin at a (polypropylene/polyamide) weight ratio of >=0.05 and <1.86 and containing 1-35 pts.wt. of a modified polyolefin based on 100 pts.wt. of the sum of the polypropylene resin and the polyamide resin. A polyamide fiber exhibiting little lowering of stress by water-absorption and having excellent creep characteristics can be produced by this process. A light-weight low-water- absorbing fiber suitable for the use requiring the above performances is easily produced. Accordingly, the obtained fiber is suitable for the use as an industrial material or a material for living.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide fiber having creep properties equivalent to those of polyamide fiber, low water absorption, light weight and requiring no drying step during molding, and a method for producing the same.

[0002]

2. Description of the Related Art Polyamide fibers are excellent in physical and chemical properties and have good creep properties, and are used for ropes, nets, carpet clothes and the like. However, on the other hand, the amide group (-CONH-) has unfavorable performance such as dimensional change due to water absorption and a decrease in mechanical strength, and its marketability is limited. In addition, the process is complicated such that a drying step is required even during spinning, which leads to an increase in cost. Further, it has a drawback that it is heavier than a polyolefin fiber and becomes heavier due to water absorption when wet.

On the other hand, since polypropylene fibers are non-water-absorbing, there is almost no deterioration in the physical properties when wet, and there are many advantages such as the need for a drying step during spin molding. However, the strength is lower than that of polyamide fiber, and it is not often used in the field where strength is required. Especially, it is not often used in the field where the creep property is important.

Therefore, a resin composition having both the excellent characteristics of a polyamide resin and a polypropylene resin, that is, a polyamide resin, which has been conventionally used, that is, excellent abrasion resistance, electric characteristics, heat resistance, mechanical strength, oil resistance, and Modification with grafting an unsaturated carboxylic acid or a derivative thereof on a polyamide resin and polypyroprene for the purpose of obtaining a resin composition having low water absorption, hot water resistance, metal halide resistance, and low temperature impact resistance of a polypropylene resin. Regarding melt-mixing polypropylene to obtain a composition having an excellent balance of strength, heat distortion resistance, appearance, and moldability, Japanese Patent Publication No. 42-12546, Japanese Patent Publication No. 45-30945, and Japanese Patent Publication No. 30945 have been disclosed. 50-76
36 publications and the like.

Further, by utilizing such excellent properties,
Practical application is being considered for applications requiring strength and heat distortion resistance such as automobile parts, electric appliances, mechanical parts, industrial parts,
Practical application has been made in some areas.

However, in order to improve the drawbacks of polyamide resin and polypropylene resin, a resin composition obtained by mixing both resins by a usual method, or a resin composition obtained by melt-mixing a polyamide resin and modified polypropylene Has poor compatibility. Particularly in the field of fibers, poor compatibility causes many spinning breaks, stretch breaks, and melt fractures, and deteriorated products tend to adhere to the nozzles, making continuous operation difficult for a long time. Further, the obtained fibers also have drawbacks such as low strength, large decrease in strength due to water absorption, and poor creep characteristics.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polyamide fiber having excellent creep properties and having a small decrease in strength due to water absorption, and a method for producing the same.

[0008]

DISCLOSURE OF THE INVENTION According to the present invention, a fiber obtained by mixing a polyamide resin having good creep properties with a polypropylene resin having poor creep properties and a modified polyolefin is
It was completed by unexpectedly finding that the good creep properties of the polyamide resin are maintained when certain conditions are satisfied.

That is, the above problem is that the weight ratio of polypropylene resin / polyamide resin is 0.05 or more and less than 1.86 and the total amount of polypropylene resin and polyamide resin is 100 parts by weight and the modified polyolefin is 1 to 35 parts by weight. It has a creep property of 35.
The problem can be solved by the polyamide-based fiber having a ratio of less than 100% and a method for producing the same.

The polypropylene resin used in the present invention may be a propylene homopolymer or a propylene copolymer. Here, the propylene copolymer is a block copolymer or a random copolymer of propylene and another α-olefin, and examples thereof include a propylene-ethylene copolymer and a propylene-butene-1 copolymer. These polypropylene resins may be used alone or in combination of two or more.

The polyamide resin used in the present invention is not particularly limited, but is obtained from polylactams such as polyamide 6, polyamide 11 and polyamide 12, dicarboxylic acids such as polyamide 66, polyamide 610, polyamide 612 and polyamide 46 and diamines. Copolymer polyamides such as polyamides, polyamide 6/66, polyamide 6/12, polyamide 6/66/610, polyamide 6 / 6T (T: terephthalic acid component), aromatic dicarboxylic acids such as isophthalic acid and meta Mention may be made of semiaromatic polyamides, polyesteramides, polyetheramides and polyesteretheramides obtained from xylenediamine or alicyclic diamines. Among them, polyamide 6 resin is preferable because it has good spinnability.

There are various types of modified polyolefins, but usually, a carboxylic acid group (acetic acid group, acrylic acid group, methacrylic acid group, fumaric acid group, itaconic acid group, etc.), a carboxylic acid metal base (sodium salt, Calcium salt, magnesium salt, zinc salt, etc., carboxylic acid ester group (methyl ester group, ethyl ester group, propyl ester group, butyl ester group, vinyl ester group, etc.), acid anhydride group (maleic anhydride group, etc.) and It is a polyolefin having at least one functional group selected from epoxy groups.

As the polyolefin, polyethylene,
Examples thereof include polypropylene, polybutene, ethylene / propylene copolymers, ethylene / butene copolymers, ethylene / hexene copolymers, and copolymers containing a small amount of diene therein.

The melt flow rate (MFR) of the modified polyolefin is not limited, but usually 0.01 to 100 g /
It is 10 minutes, preferably 0.1 to 10 g / 10 minutes. These modified polyolefins may be used alone or in combination of two or more.

In the present invention, the weight ratio of polypropylene resin / polyamide resin needs to be 0.05 or more and less than 1.86, preferably 0.11 or more and less than 1.50. If the weight ratio of polypropylene resin / polyamide resin is less than 0.05, the water absorbency of the fiber is high, so that there is a problem of physical property deterioration due to water absorption and yarn breakage due to foaming during molding, which necessitates a drying step. Further, the original lightness of the PP resin is lost. On the contrary, when it is 1.86 or more, the creep property of the obtained fiber is remarkably deteriorated.

The modified polyolefin is 1 to 35 parts by weight, preferably 4 to 30 parts by weight, particularly preferably 5 to 20 parts by weight, based on 100 parts by weight of the total amount of polypropylene resin and polyamide resin. 1 modified polyolefin
If the amount is less than parts by weight, it is difficult to improve the compatibility between the polyamide resin and the polypropylene resin, and it is impossible to impart desired creep properties to the obtained fiber. In addition, a lot of eye blemishes occur in the nozzle portion during spinning, and spinning breakage easily occurs during long-term operation. On the other hand, when the amount of the modified polyolefin exceeds 35 parts by weight, the strength of the obtained fiber is lowered and the creep property is also poor.

If desired, other additives may be added to the resin composition of the present invention within a range that does not impair the characteristics of the above components. Additives that can be blended here include dyes, pigments, fillers, nucleating agents, fibrous materials, plasticizers, lubricants, release agents, coupling agents, foaming agents, heat resistant agents, weather resistant agents, flame retardants, antistatic agents. Agents and the like.

The resin composition of the present invention is prepared by mixing or kneading the respective components in the above-mentioned mixing ratio, and the melt kneading method is preferable as the method. Mixing is done using a Banbury mixer, Henschel mixer, etc.
A single-screw or twin-screw extruder is generally used as the kneading machine. The temperature at the time of melt-kneading may be appropriately selected depending on the components, the blending amount, etc., so that the melting of each component does not proceed sufficiently and does not decompose. It is usually selected in the range of 180 to 350 ° C, preferably 200 to 300 ° C.

In the method for producing the fiber of the present invention, the above resin composition is sheared at a shear rate of 250 to 2500 sec ^-1, preferably 350 to 1500 sec ^-1 , and a die temperature of 220 to 3.
Melt spinning is performed under the condition of 30 ° C., preferably 240 to 280 ° C. As the melt spinning nozzle, any nozzle may be used, but a nozzle cross-sectional area of 0.503 to 3.14 mm, a nozzle shape of a circle or an elliptical shape with an aspect ratio of 1.0 to 1.6 is preferable.

The strand after exiting from the nozzle is cooled in a water tank, and the cooling temperature is preferably maintained at 20 ° C. or lower.

The stretching may be carried out by using a pressurized steam tank, a hot air tank, a catalyst bath, a hot plate, a hot roll, a wet tank, etc., alone or in combination, but preferably a multi-stage stretching by combining them. In particular, a combination in which the first stage is wet-stretched and the second and subsequent stages are stretched with hot rolls is preferable. Stretching temperature is 80-1
50 ° C, preferably 90-140 ° C is suitable. The draw ratio must be 3 to 16, and preferably 3
-11, particularly preferably 3-8. When the draw ratio is less than 3, the creep property is not improved even when the composition is made into fibers, and when it exceeds 16, whitening is likely to occur.

The creep characteristic of the polyamide fiber in the present invention is within 35%, preferably within 25%. Three
If it exceeds 5%, the dimensions will change with time when a load such as a rope is applied, which is not preferable. The creep property in the present invention is 2 g at the tip of a sample having a length of 30 cm.
S /% difference between the rate of change in elongation after 24 hours when a load of / d is applied (b) and the rate of change in elongation after 10 minutes (a) =
It is calculated by (b)-(a). Here, the rate of change in elongation is expressed by the following equation.

[Equation 1]

[0023]

The present invention will be described in more detail with reference to Examples and Comparative Examples. The temperature decrease due to water absorption and the necessity of a drying step during spinning were measured as follows.

(1) Strength reduction due to water absorption After standing in water at 23 ° C. for 7 days, remove water with a dry cloth,
A tensile test was performed to determine the breaking strength (d). Further, the breaking strength (c) at the time of absolutely dry was also obtained, and {(c)-(d)}
/ C was taken as the strength reduction due to water absorption.

(2) Necessity of Drying Step After pelletizing with a twin-screw extruder, when it is applied to the extruder for spinning, it is not dried, and if it is directly fed to the hopper, there is no spinning. I said. Also,
When spinning could not be performed due to foaming at the nozzle outlet, it was left in a vacuum dryer (80 ° C.) for 3 to 4 hours and then fed to a hopper to try spinning. And the thing which became spinnable by it was set as "existence".

Example 1 Polyamide 6 having a relative viscosity of 2.52 and an amino terminal concentration of 4.9 × 10 ⁻⁵ equivalent / g was 18.0.
Kg, MFR (JIS K 6758) 3.2g / 1
2.0 kg of propylene homopolymer for 0 minutes (PP / PA
Weight ratio = 0.11), MFR (JIS K6758) 1.0 g / 10 minutes graft-modified polypropylene obtained by adding maleic anhydride 0.35% by weight to 1.0 g / 10 (5 parts by weight). Put in a tumbler and mix for 10 minutes.
Melt pelletizing was performed at 50 ° C. to obtain a polyamide 6-based resin composition.

1 mmφ of this polyamide 6 resin composition
Is extruded at 260 ° C. by a 40 mmφ monofilament manufacturing apparatus equipped with a die having 20 nozzles, and the strand discharged from the nozzle is rapidly cooled with water at 30 ° C.,
The unstretched yarn was wound up by the first roll, guided in-line to the wet drawing tank (100 ° C.), and wound up by the second roll.

The draw ratio was represented by the continuous ratio of the second roll and the first roll, and was molded at 4 times. The obtained polyamide 6-based fiber had a thickness of 400 denier, and the shear rate at the nozzle was 1000 sec ^-1 . As shown in Table 1, it was confirmed that the obtained polyamide 6-based fiber had excellent creep properties, low water absorption, and a small decrease in physical properties due to water absorption.

[Examples 2 to 5] Propylene homopolymer /
Polyamide 6 fibers were molded in the same manner as in Example 1 except that the weight ratio of polyamide 6 and the amount of graft modified polypropylene were changed. The results, as shown in Table 1, were all excellent in creep properties, and the strength was not significantly reduced by water absorption, and a drying step was not necessary.

Example 6 After winding on a second roll,
Subsequently, a polyamide 6-based fiber was molded in the same manner as in Example 3 except that drawing was performed between hot rolls at 130 ° C. and drawing was performed in two stages in-line. The draw ratio was represented by the speed ratio between the first roll and the take-up roll, and was 8 times for the two-stage drawing. The results are shown in Table 1.

[Comparative Example 1] A polyamide 6-based fiber was molded in the same manner as in Example 1 except that the weight ratio of propylene homopolymer / polyamide 6 was 0.04. However, although the obtained polyamide 6-based fiber has excellent creep properties as shown in Table 1, it has a high water absorption and cannot be spun due to yarn breakage unless a drying step is provided. The obtained sample also showed a large decrease in strength due to water absorption.

[Comparative Example 2] A polyamide 6-based fiber was molded in the same manner as in Example 3 except that the amount of the graft-modified polypropylene was changed to 40 parts by weight. However, as shown in Table 1, the obtained polyamide 6-based fiber was inferior in creep property.

Comparative Example 3 A polyamide 6 fiber was molded in the same manner as in Example 1 except that the weight ratio of propylene homopolymer / polyamide 6 was 2.33. As a result, as shown in Table 1, the creep characteristics were inferior.

[Comparative Example 4] 12.0 kg of polyamide 6
8.0 kg of propylene homopolymer (weight ratio of propylene homopolymer / polyamide 6 = 0.67) and 0.1 kg (0.5 parts by weight) of graft-modified polypropylene were extruded by a twin-screw extruder. A tar was generated, and after about 3 hours, the strand was broken at the nozzle portion. Also, when cutting with a cutter, I couldn't cut it neatly, and I couldn't pelletize it because it became a series of beads.

[0035]

[Table 1]

[0036]

As described above, according to the present invention,
It is possible to obtain a polyamide-based fiber that is excellent in creep characteristics with little decrease in strength due to water absorption, and is easy to obtain a lightweight, low-water-absorption fiber suitable for applications requiring the above-mentioned performance. Therefore, the polyamide-based fiber of the present invention is suitably used for industrial materials and household materials.

Front page continued (72) Inventor Ryosuke Kamei 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Akira Kawasaki Plastic Research Laboratory

Claims (2)

[Claims] 1. A resin composition in which the weight ratio of polypropylene resin / polyamide resin is 0.05 or more and less than 1.86, and the modified polyolefin is 1 to 35 parts by weight based on 100 parts by weight of the total amount of polypropylene resin and polyamide resin. Polyamide fiber made of a material and having a creep property within 35%. 2. A resin composition in which the weight ratio of polypropylene resin / polyamide resin is 0.05 or more and less than 1.86, and the modified polyolefin is 1 to 35 parts by weight based on 100 parts by weight of the total amount of polypropylene resin and polyamide resin. A method for producing a polyamide fiber having a creep property of 35% or less by melt-spinning the product and drawing at a draw ratio of 3.0 to 16.0.