JP2849925B2 - Polyamide-based polymer alloy fiber and method for producing the same - Google Patents

Description

The present invention relates to a fiber comprising a polymer alloy of a polyamide and a polyolefin, which has advantages of both polymers, namely, hydrophilicity and dyeability of the polyamide and oxidation resistance of the polyolefin. The present invention relates to a polymer alloy fiber that makes use of the properties and alkali resistance.

(Prior art) In order to improve the oxidation resistance of a polyamide fiber, a method of spinning with a polyolefin has been known for a long time.
For example, in Japanese Patent Publication No. 42-11697, 2-7%
Of polyolefins. Examples of the conjugate fiber include JP-B-42-8733 and JP-B-47-50012. There is also an example of a battery separator utilizing the oxidation resistance and hydrophilicity of such a conjugate fiber (JP-A-50-154745).
No., JP-A-55-25921).

(Problems to be Solved by the Invention) However, polyamide and polyolefin are poor in compatibility and adhesiveness, so it is difficult to draw, and mixed spinning has low strength, and composite spinning can only be easily peeled.

The present invention relates to a polymer alloy fiber in which a polyamide and a polyolefin are mixed at an arbitrary ratio. The polymer alloy fiber has an advantage that drawing is easy, fineness is high, and high strength. It is.

(Means for Solving the Problems) As a means for solving the above problems, the present inventors have found that a polyolefin island component as fine as possible with respect to a polyamide as a sea component is produced. That is, the diameter of the cross section of the granular polyolefin fiber is 5 μm.
If it is less than this, the affinity with the polyamide is good and the separation of both components is small.

The invention according to claim 1 of the present invention provides a polyamide-based polymer in which an aliphatic polyamide is a sea component, and a granular polyolefin having a diameter of less than 5 μm in fiber cross section is an island component, and the island component is discontinuous in the fiber length direction. A polyamide-based polymer alloy conjugate fiber comprising an alloy as a first component, a polyolefin identical to the island component polyolefin as a second component, and the first component forming at least 30% of the fiber cross-sectional area and at least 60% of the fiber surface. It is.

Nylon-6, nylon-
A homopolymer or copolymer such as 66, nylon-12, nylon-11, etc. is used. Of these, nylon-6 and nylon-66 are inexpensive and suitable for practical use. The polyolefin is polypropylene, polyethylene,
Although homopolymers or copolymers of α-olefins such as polybutene and polymethylpentene are used, polypropylene is practically preferable.

The cross-sectional shape of the island component is not necessarily circular, and if it is not circular, its diameter is the largest part of the diameter.
In addition, polyolefin is mixed as a raw material in a granular form in a sea component by a polymer blend method, and an island component obtained by spinning the same is discontinuous in a fiber length direction.

The first component of the composite fiber forms at least 30% of the fiber cross-sectional area and at least 60% of the fiber surface. Therefore, the cross-sectional shape of the fiber may be a core-sheath type or a side-by-side type. A part of the island component of the first component appears at the boundary surface between the first component and the second component, and since the first component and the second component are compatible with the second component, the adhesive force between the two components is strong, and the two components are hardly peeled off. ing.

FIG. 1 shows a cross-sectional shape of the core-sheath composite fiber. First
In the polymer alloy as the component (3), the island component (2) is dispersed in the sea component (1) in the form of dots. The island component (2) in the first component (3) and the second component (4) which is a polyolefin
Are mixed and integrated with each other on the boundary line, and the boundary line becomes uneven, thereby increasing the contact area of both components. Next, FIG. 2 shows a cross-sectional view of the parallel type composite fiber. The first component accounts for 60% or more of the fiber surface.
The boundary between the two components is also uneven due to the mixture of the island component and the second component.

The mixing ratio of the polyamide and the polyolefin in the polymer alloy should be at least 50% by weight of the polyamide in order for the polyamide to be the sea component and the polyolefin to be the island component.
It is preferably at least 60% by weight. Further, in order to obtain the composite fiber, the polyolefin is at least 20% by weight as an island component,
Preferably, when the content is 30% by weight or more, stable production can be achieved. Therefore, when polyamide is represented by PA and polyolefin is represented by PO, the mixing ratio of PA and PO (PA / PO) is 50/50 <PA / PO ≦ 8.
0/20, preferably 60/40 <PA / PO ≦ 70/30. The mixing ratio may be selected within this range so as to obtain necessary properties such as hydrophilicity, dyeability, oxidation resistance, and alkali resistance of the target fiber.

The composite ratio of the polymer alloy and the polyolefin in the composite fiber is determined so that the polymer alloy as the first component occupies 60% or more of the fiber surface by setting the polymer alloy to 30% or more in fiber cross-sectional ratio. Can be manufactured stably.

Such a polymer alloy fiber of claim 1 can be manufactured as follows.

The invention according to claim 2 is a sea-island type polyamide in which a granular polyolefin having a diameter of less than 5 μm is mixed and integrated as an island component with the sea component of the aliphatic polyamide, and the melt flow rate at 290 ° C. is 20 or more and less than 90. The diameter of the polymer alloy is the first component, and the same polyolefin as the first component is the second component. The melting point + 10 ° C. or higher so that the first component occupies 30% or more of the fiber cross-sectional area and 60% or more of the fiber surface area. Melt spinning at a temperature below 360 ° C 2
2. The method for producing a polymer alloy conjugate fiber according to claim 1, wherein the polyolefin having a diameter of less than 5 [mu] m is made discontinuous in the length direction of the fiber by drawing the polyolefin twice or more times.

In the polymer alloy of the present invention, a raw material resin in which a particulate polyolefin having a diameter of less than 5 μm is mixed in an aliphatic polyamide in advance is melt-spun. Therefore, the polyolefin which is an island component in the fiber after spinning has a diameter of 5 μm.
This is not the case, and the film can be favorably dispersed in the sea component and stretched together with the sea component. The diameter of the island component in the raw material resin is preferably 3 μm or less, more preferably about 1 μm. This raw material resin has a melt flow rate (MFR) at 290 ° C. of 20 or more and less than 90. If the spinning temperature of the raw resin having an MFR within this range is selected, good spinning can be achieved.

The above MFR is measured according to JIS7210, expressed by weight (2169 g) and flow rate (g) for 10 minutes.

Spinning temperature is the melting point of polymer alloy + 10 ° C or more and 360 ° C
Is less than. If it exceeds 360 ° C., the decomposition of polyamide is remarkable. If the polyamide is nylon-6, the temperature must be between 250 ° C and 360 ° C. If the polyamide is nylon-6, the temperature must be between 270 ° C and less than 360 ° C.
The MFR is selected so as to take a preferable value for spinning.

(Effect of the Invention) Even when spinning a fiber having a sea-island structure from a mixture of a polyamide and a polyolefin, a large number of thread breaks occurred.
Good spin drawability can be obtained by using a polymer alloy of a type which is dispersed in a polyamide with a particle size smaller than the above. Further, the composite fiber of polyamide and polyolefin was liable to cause separation between components. However, by using a polymer alloy of polyamide and polyolefin, a composite fiber having no separation between components was obtained.

(Examples) Examples 1 to 3 Nylon-6 (Ny) is a sea component and polypropylene (PP) is used.
Polyamide polymer alloy QA-5000 containing
(Trade name, manufactured by Mitsui Petrochemical Industry Co., Ltd.).
The mixing ratio of the two components is 60% by weight of nylon-6 and 40% by weight of polypropylene.
It was dispersed in the form of μm particles. The MFR was 45 g / 10 minutes at 290 ° C.

This polymer alloy fiber and polypropylene (MFR45g
/ 10 min) as a composite component and spun at a different composite ratio (area%). The spinning conditions were as follows: melt spinning was performed at a spinning temperature of 290 ° C. at a spinning temperature of 290 ° C., and the drawing was performed in hot water at 95 ° C. Table 1 shows the fiber shape, the composite ratio, the ratio of the polymer alloy occupying the fiber surface (surface ratio), the fiber elongation, and the like of the polymer alloy composite fiber.

Comparative Examples 1-3 Polypropylene single fiber, nylon-6 as comparative examples
And a parallel type composite fiber comprising the same polymer alloy and polypropylene as in Example 1 was spun. Table 1 shows the fiber properties similar to those of the examples.

Next, Table 1 shows the results of tests on the following three items as to whether or not the above examples and comparative examples were suitable as battery separator materials.

As a nonwoven fabric for a test sample, 70% of each fiber (fiber length 51 mm) of the above-mentioned Example and Comparative Example and 30% of a composite fiber (2 denier, fiber length 51 mm) made of high density polyethylene sheathed with polypropylene as a core. , 140 ° C., after a basis weight 75 g / m ² of thermal bonding nonwoven by hot air for 1 minute, linear pressure 33 kg / cm
The non-woven fabric having a thickness of 0.23 mm was formed by hot working with a flat heat roll (140 ° C.).

 The three test methods are as follows.

Hydrophilicity test (electrolyte absorption rate test) Three test pieces measuring 2.5 × 18 cm are taken from the vertical direction of the sample, and the sample is brought into a water equilibrium state. Next, the test piece is fixed with a pin on a horizontal bar supported at a certain height on a water tank containing a caustic potash solution having a specific gravity of 1.30 (20 ° C.) at 20 ± 2 ° C. The lower end of the test piece is lined up, the horizontal bar is lowered, and the test piece is set up vertically so that the lower end of the test piece is immersed in the liquid by 5 mm.

Alkali resistance test Three test specimens of 10 cm × 10 cm were sampled from a sample, and the weight (W) in a state where water equilibrium was reached was measured up to 1 mg. 7 at ± 2 ° C
Save for days.

Thereafter, the sample is washed with water until it reaches the neutralization point, dried, and again weighed (W ₁ ) in a state of reaching water equilibrium, and the alkali resistance is determined by the following equation.

Alkali resistance = (W−W ₁ ) / W × 100 Oxidation resistance test Three test pieces of 10 cm × 10 cm are sampled from a sample, and the weight (W) in a state of reaching water equilibrium is measured to 1 mg. Next, it is immersed in a mixed solution obtained by adding 50 cc of a 30% KHO solution to 250 cc of a 5% KMnO ₄ solution, and immersed at 50 ± 2 ° C. for 1 hour.

Thereafter, the sample is washed with water until it reaches the neutralization point, dried, and again weighed (W ₁ ) in a state where water equilibrium is reached, and the oxidation resistance is determined by the following equation.

Oxidation resistance _{= (W-W 1) /} W × 100 Examples 4 to 8 and Comparative Examples 4 and 5 The same core-sheath type composite fiber as polypropylene as in Example 1 (composite ratio of 50:50) was spun by changing the kind and weight ratio of nylon of the first component polymer alloy. did. Table 2 shows the content of the first component, the composite ratio of the composite fiber, the spinnability, and the same hydrophilicity test results as in Examples 1 to 3.

(Effect of the Invention) The polyamide-based polymer alloy fiber of the present invention has the property of incorporating the chemical resistance of polyolefin while retaining the hydrophilicity and dyeing properties of polyamide. It can also be applied to applications requiring alkali resistance. In particular, since the material of the battery separator is hydrophilic, it is well suited to liquids, and is optimal because it has good oxidation resistance and alkali resistance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the core-in-sheath type composite fiber according to the first aspect of the present invention. FIG. 2 is a sectional view of the parallel type composite fiber. In the figure, (1) sea component, (2) island component, (3) first component, (4) second component

Claims (2)

(57) [Claims] 1. A polyamide polymer alloy comprising a sea component of an aliphatic polyamide, a granular polyolefin having a diameter of less than 5 μm in a fiber cross section as an island component, and a polyamide polymer alloy in which the island component is discontinuous in the fiber length direction. The same polyolefin as that of the island component is used as the second component, and the first component is 30% or more of the fiber cross-sectional area and 60% of the fiber surface.
% Of a polyamide-based polymer alloy composite fiber. 2. The aliphatic polyamide has a diameter of 5 μm in the sea component.
The polyolefin having a particle size of less than 1 is mixed and integrated as an island component, and has a melt flow rate at 290 ° C of 20 or less.
A sea-island type polyamide-based polymer alloy having a value of not less than 90 is used as a first component, and a polyolefin identical to the polyolefin in the first component is used as a second component. % By melting and spinning in a temperature range of 10 ° C. or more and less than 360 ° C. and stretching it twice or more, thereby making the particulate polyolefin having a diameter of less than 5 μm discontinuous in the fiber length direction. The method for producing a polymer alloy conjugate fiber according to claim 2, characterized in that: