JPH04272222A - Light-weight conjugate fiber - Google Patents

Abstract

PURPOSE:To provide a conjugate fiber having light-weight which is a characteristic feature of polypropylene as well as excellent dyeability and heat-resistance which are characteristic features of polyamide. CONSTITUTION:The objective conjugate fiber has a density of <=1.01g/cm<3> and composed of (A) a core component consisting of a mixture of a polypropylene graft polymer grafted with 1-3wt.% of maleic anhydride and a polyamide at a weight ratio of 70/30 to 90/10 and (B) a sheath component consisting of a polyamide.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight composite fiber suitable for clothing made of polyamide and polypropylene graft polymer.

0002

[Prior art] Polypropylene fiber has a density of 0.91g.
It is smaller than water at about /cm3, and is the lightest fiber, including natural fibers and synthetic fibers, and has high strength and excellent elastic properties. However, it has the drawbacks of low heat resistance (melting point of about 170°C) and poor dyeability.

[0003] In order to take advantage of the lightweight feature of polypropylene and improve its dyeability, a concentric composite fiber containing polypropylene as a core component and polyamide as a sheath component was proposed in JP-A-61-83314. There are, but
These fibers tend to peel off at the interface, causing problems in drawing operability and the like. Furthermore, JP-A-60-81316 proposes a composite fiber having polypropylene as a core component and a mixture of polypropylene and polyamide as a sheath component.
Since this fiber uses a mixture of polypropylene and polyamide, which have poor compatibility, as a sheath component, there is a practical problem in that the mixed spots turn into dyed spots.

0004

[Problems to be Solved by the Invention] The present invention is a composite fiber that takes advantage of the lightweight feature of polypropylene and covers the disadvantages of poor dyeability and heat resistance with polyamide. The aim is to provide composite fibers that are free from these problems.

[0005]

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have found that when a specific amount of maleic anhydride is grafted onto polypropylene, the compatibility with polyamide is improved, and a uniform bond with polyamide is obtained. The inventors have discovered that a mixture can be obtained, and have arrived at the present invention.

That is, the present invention provides 1 maleic anhydride.
A composite fiber whose core component is a mixture of ~3% by weight grafted polypropylene-based graft polymer and polyamide in a weight ratio of 70/30 to 90/10 and whose sheath component is polyamide, and whose density is 1.01 g/cm3 or less. The gist is a lightweight composite fiber that is characterized by certain features.

The present invention will be explained in detail below. A feature of the present invention is the use of a mixture of polyamide and a polypropylene-based graft polymer grafted with maleic anhydride as a core component. By mixing polyamide with the core component, peeling from the polyamide of the sheath component is suppressed, and at the same time, dyeability is improved.

[0008] Ordinary polypropylene has poor compatibility with polyamide, and simply mixing it with polyamide does not allow the polyamide to be uniformly dispersed in the polypropylene, making it impossible to obtain homogeneous fibers. However, polypropylene-based graft polymers grafted with maleic anhydride,
It has good compatibility with polyamide and provides a homogeneous mixture with polyamide.

[0009] If polyamide is not mixed into the core component, the polypropylene graft polymer will have a large shrinkage stress, so when winding the melt-spun yarn, if the winding tension is high, the yarn tube may come off from the winder. However, when polyamide is mixed with the core component, the shrinkage stress is alleviated and the winding tension can be increased.

The polypropylene graft polymer used in the present invention must be a polypropylene grafted with 1 to 3% by weight of maleic anhydride. If the amount of grafted maleic anhydride is less than this range, the compatibility with polyamide will be insufficient, and conversely, if the amount of grafted maleic anhydride is more than this range, the original strength and elastic characteristics of polypropylene will be impaired. Moreover, the melt viscosity increases and the melt spinnability deteriorates, which is also unfavorable from an operational point of view.

The polypropylene to which maleic anhydride is grafted is isotactic polypropylene, and the melt flow rate (MF value) is in accordance with ASTM D-123.
8(L), those with a value of 20 g/10 minutes or less are preferably used.

[0012] As the polyamide in the present invention, nylon 6 (polycapramide), nylon 66 (polyhexamethylene adipamide), and polyamides containing these as main components are preferably used. Polyamide has a relative viscosity (9
A suitable solution is one with a value of about 2.0 to 3.5 (measured using 6% sulfuric acid as a solvent, concentration of 1 g/dl, and temperature of 25° C.).

[0013] If the MF value of polypropylene or the relative viscosity of polyamide is not appropriate, the melt viscosity will be too high or too low, resulting in yarn bending directly under the spinneret during composite spinning, or sheath components A problem arises in that the core component cannot be completely covered.

[0014] The mixing ratio of the graft polymer and polyamide in the core component needs to be a weight ratio of 70/30 to 90/10. If the mixing ratio is smaller than this range, the core component and sheath component will easily separate, causing operational problems; if the mixing ratio is larger, the proportion of the polypropylene graft polymer in the composite fiber will decrease, making it difficult to achieve the intended purpose. It is not possible to obtain fibers with low density.

Further, in the composite fiber of the present invention, the core/sheath weight ratio is such that the density of the fiber is 1.01 g/cm3 or less,
The selection should be made so as to obtain a fiber in which the core component is completely covered with the sheath component, but it is usually 50/50 to 80/2.
It is set to 0. If the proportion of the core component is too small, the desired weight reduction will not be achieved, and if it is too large, the core component will be partially exposed on the fiber surface, causing problems in workability or staining spots.

The conjugate fiber of the present invention can be produced by melt spinning and drawing according to a conventional method for producing a core-sheath type conjugate fiber.

At this time, it is necessary to apply heat to the stretching. Ordinary nylon fibers with a low glass transition temperature can be drawn without applying any particular heat;
Since the fiber of the present invention contains a polypropylene-based graft polymer in the core component, the core component and sheath component cannot be drawn uniformly unless heat is applied, resulting in poor drawing operability and yarn unevenness. , causing staining spots. For this reason, it is necessary to set the stretching temperature to 100°C or higher. (It is appropriate that the upper limit of the stretching temperature is about 200°C, at which point fusion of the threads does not occur.)

[0018] The composite fiber of the present invention has a weight of 1.01 g/cm3.
It has the following density, and although it varies depending on the spinning conditions, it usually has a strength of 3 g/d or more, an elongation of 20 to 80%, and an initial Young's modulus of 20.
It has characteristics of more than g/d.

Although the single yarn fineness and total fineness are not particularly limited, it is preferable that the single yarn fineness is 1 to 10 d and the total fineness is 50 to 500 d.

[0020]

[Examples] The present invention will be specifically explained below using examples. Note that the method for measuring characteristic values in the present invention is as follows.

(1) Strength and elongation Measured using Autograph DSS-500 manufactured by Shimadzu Corporation at a sample length of 30 cm and a tensile speed of 30 cm/min.

(2) Initial Young's Modulus This was determined from the initial slope of the load-extension curve obtained when measuring strength and elongation.

(3) Density was measured using a toluene-carbon tetrachloride density gradient tube at 25°C.

(4) The composite yarn of the dyeable sample and the nylon 6 yarn produced by the usual two-step process of melt spinning and drawing were simultaneously tube-knitted, and after scouring in hot water at 60° C. containing a nonionic activator for 30 minutes. , and the dyeing properties were evaluated using the following formulation. Bayer acid dye: Tel
on Fast Navy blue R 1%owf
, acetic acid 0.2 ml/l, Sando Co., Ltd. leveling agent: Sand
Using a dye bath containing 1% owf of zol KB, the bath ratio is 1/1.
00 for 30 minutes under boiling. The evaluation of dyeability was carried out using the following 3 steps using the standard nylon 6 thread using the two-step method.
I went in stages. ○: Equal, △: Slightly inferior, ×: Inferior

[
Example 1 A mixture of a graft polymer obtained by grafting 1.3% by weight of maleic anhydride and nylon 6 (N6) with a relative viscosity of 2.60 was used as a core component and a relative viscosity of polypropylene with an MF value of 15 g/10 min. 2.60 N6 was supplied as a sheath component to a normal extruder type composite spinning machine, and the spinning temperature was 2.
The yarn was discharged from a spinneret having 36 spinning holes with a hole diameter of 0.3 mm at 75°C, cooled, solidified, and oiled, passed through a pair of unheated rollers, and wound at a speed of 3500 m/min.
A concentric core-sheath type composite yarn of 50d/36f was obtained. In addition, the core/
The sheath weight ratio was 70/30, and the mixing ratio of the core components was changed as shown in Table 1.

The obtained undrawn yarn is pre-stretched by a factor of 1.01 between an unheated supply roller and a first drawing roller at a temperature of 90°C, and then subjected to a second drawing at a temperature of 1700°C with the first drawing roller. It was stretched 1.94 times between rollers and wound up at a speed of 680 m/min. Table 1 shows the characteristic values of the obtained drawn yarn. (No. 1, No. 2 and No. 5 are comparative examples.)

[0027]

[Table 1]

No. 1, which is an embodiment of the present invention. 3 and no.
Sample No. 4 was lightweight with a density of 1.01 g/cm 3 or less, had good dyeability, and had good spinning and drawing properties.

On the other hand, the comparative example No. In 1,
During stretching, fluff was observed, and No. In No. 2, the stainability was not very good, and in No. With No. 5, sufficiently lightweight fibers could not be obtained.

Example 2 A mixture of a graft polymer obtained by grafting 1.2% by weight of maleic anhydride to polypropylene with an MF value of 12 g/10 min and nylon 66 with a relative viscosity of 2.50 was used as a core component.
Using nylon 66 with a relative viscosity of 2.50 as a sheath component, No. 1 of Example 1 was used. A core-sheath type composite yarn was produced in the same manner as in Example 4.

There were no problems in the operability of spinning and drawing, and the yarn properties were strength 4.21 g/d, elongation 32.9%, initial Young's modulus 31.4 g/d, and density 1.008 g/cm3. .

[0032]

According to the present invention, in the polyamide-polypropylene sheath-core type composite fiber, since polypropylene grafted with maleic anhydride is used, it has good compatibility with polyamide and prevents peeling and staining spots at the interface. It is possible to obtain a composite fiber that has both the light weight of polypropylene and the good dyeability and heat resistance of polyamide.

Claims (1)

[Claims] 1. A core component comprising a mixture of a polypropylene graft polymer grafted with 1 to 3% by weight of maleic anhydride and a polyamide in a weight ratio of 70/30 to 90/10.
A composite fiber whose sheath component is polyamide, and whose density is 1.
．． A lightweight composite fiber characterized by having a weight of 0.01 g/cm3 or less.