JPH1072528A - Polyamide pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain polyamide pellets for spinning, which have a relatively high titanium oxide content and which cause only a low frequency of end breakage even in a high-speed spinning. SOLUTION: Polyamide pellets for spinning contain 3 to 70wt.% titanium oxide and polyamide. Titanium oxide concn. in the polyamide is reduced to 2wt.% by dilution with the same kind of polyamide. The filtration pressure- elevation rate is not above 9.8 MPahr as determined with a filter having apertures of 5μm at a filtration rate of 80g/min.cm<2> at 285 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-concentration titanium oxide having excellent yarn-making operability and yarn quality by finely dispersing titanium oxide added for the purpose of matting or imparting opacity to polyamide fibers. The present invention relates to a yarn-forming polyamide pellet containing:

[0002]

2. Description of the Related Art Polyamide fibers have excellent strength, durability, stretchability, and dyeability, and are therefore used for clothing such as sportswear and stockings, and for industrial uses such as carpets. In these uses, titanium oxide is usually added as a white pigment in an amount of 3% by weight or less as a white pigment in order to eliminate the glittering feeling of the fiber and to improve the high order processability. As for the titanium oxide-containing pellets used for this purpose, generally, a method is employed in which pellets having the same titanium oxide concentration as the titanium oxide concentration contained in the yarn are produced, and the yarn is produced as it is. However, depending on the application utilizing the characteristics of titanium oxide, the concentration of titanium oxide contained in the yarn needs to be 3% by weight or more.

For example, JP-A-5-247723 discloses that titanium oxide may be added in an amount of 5 to 30% by weight in fields requiring opacity such as underwear, underwear and swimwear. In addition to the above, there are the following uses to which a high concentration of titanium oxide is added. It is known to add conductive carbon black for the purpose of preventing the polyamide from electrostatic damage. In order to suppress the blackening of the yarn due to the addition of carbon black, carbon black is added to the core of the yarn, and titanium oxide is added to the sheath from 5% by weight to 10%.
In some cases, a polyamide containing a weight percent is used.

[0004] Further, since titanium oxide has an effect of blocking ultraviolet rays, a polyamide containing a high concentration of titanium oxide is also suitable for applications requiring a refreshing feeling such as umbrellas and tennis wear.

[0005] For example, even if the titanium oxide concentration in the yarn is 3% by weight or less, the production process and the yarn making process of the titanium oxide-containing pellets are rationalized, and the variety of yarn types in which the concentration of titanium oxide in the yarn is different. In order to cope with this, a pellet containing a high concentration of titanium oxide, which is called a master batch, is manufactured, and it is blended with a pellet not containing titanium oxide to form a yarn and contains a predetermined amount of titanium oxide. There is also a method for producing yarn varieties.

[0006] However, when pellets containing titanium oxide at a high concentration are used as they are, or pellets containing no titanium oxide are blended to form a yarn, foreign matter effects due to poor dispersion of titanium oxide in the pellets may result.
In some cases, yarn breakage during yarn production increases, resulting in poor operability and inability to perform yarn production. In terms of yarn quality, strength and elongation are reduced and the yarn cannot be used practically. This tendency tends to be more pronounced as the concentration of titanium oxide in the pellets and yarn increases, and as the spinning speed increases.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyamide pellet containing such a high concentration of titanium oxide as it is, or even if it is blended with a pellet containing no titanium oxide to produce a yarn, thread breakage occurs. An object of the present invention is to provide a yarn-forming polyamide pellet which has a small amount of yarn, has good yarn-making properties, and does not reduce yarn strength or elongation.

[0008]

According to the present invention, there is provided a polyamide pellet containing 3 to 70% by weight of titanium oxide and a polyamide, wherein the polyamide pellet is made of a titanium oxide by the same kind of polyamide as the polyamide. The concentration was diluted to 2% by weight, and the filtration rate was increased to 80 g / hr at 285 ° C. with a 5 μm mesh filter.
The rate of increase of the filtration pressure, measured as cm ² , is 9.
Polyamide pellets for yarn production of 8 MPa / hr or less. And "a method for producing polyamide fibers, wherein yarns are produced using the polyamide pellets."

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below.

[0010] Titanium oxide includes rutile type and anatase type having different crystal forms. Since the rutile type has high hardness,
As it wears metal pins used when processing yarn,
As the titanium oxide to be added to the polyamide pellets for spinning, an anatase type is usually used. Some titanium oxides for spinning have a compound such as Mn, Al, Zn, or Si coated on the surface of the titanium oxide in order to improve light resistance or dispersibility. The titanium oxide to be formed may or may not have these compounds coated.

The following method is available for producing pellets containing titanium oxide. (1) Titanium oxide as it is or subjected to classification treatment,
A method of polymerizing by mixing with a polyamide monomer. (2) A method in which titanium oxide is added to a polymerization apparatus during the polymerization of polyamide. (3) Titanium oxide as it is or together with a dispersing agent, etc.
A method of adding to a polyamide in a molten state after completion of polymerization. (4) A method in which polyamide pellets and titanium oxide are kneaded in a molten state using an extruder or the like. And the like, but the method of the present invention may be any method.

The polyamide mentioned here is nylon 6,6.
6. Polyamides capable of forming fibers such as copolymers, such as viscosity stabilizers such as acetic acid, light-resistant agents such as manganese compounds, heat-resistant agents such as copper compounds, other antistatic agents, dispersants, and terminal group amount regulators. An additive may be contained.

[0013] As a method for polymerizing polyamide, there are generally a continuous method and a batch method, but any method may be used.

The polyamide pellets for yarn production containing high-concentration titanium oxide of the present invention may be produced as they are,
A yarn having a different concentration of titanium oxide may be produced by blending with another polyamide pellet of the same type, or a yarn having improved properties may be produced by blending with another type of polyamide pellet.

If the titanium oxide concentration in the polyamide pellets for yarn production containing a high concentration of titanium oxide of the present invention exceeds 70%, the dispersion of titanium oxide in the pellets becomes poor, the melt viscosity becomes high, or the like. Since the elasticity of the strand after cooling becomes small, pelletization becomes difficult.

Further, the concentration of the titanium oxide is diluted to 2% by weight, and the filtration speed is 80 g / hr. If the rate of increase of the filtration pressure as measured in cm ² exceeds 9.8 MPa / hr, yarn breakage during yarn production increases, yarn production becomes impossible, or 3000 m / min.
The high-speed spinning described above becomes impossible. In addition, strength and elongation are reduced in yarn quality.

FIG. 1 is a schematic diagram of a filtration pressure measuring device used in the present invention. The measuring method is described below.

In order that the titanium oxide concentration becomes 2% by weight,
After mixing with a pellet made of the same kind of polyamide as the pellet without containing titanium oxide, about 1 kg of the dried polyamide pellet is charged into the chip hopper 1. The aluminum block heater 4 is overheated so that the temperature of the hot plate 3 becomes 285 ° C. The piston 2 is pressurized to melt the polyamide pellet on a hot plate and pressurized. Rotate gear pump 5 and 4g
/ Min. The molten polymer is discharged at a rate of 4 hours through a filter 6 having a mesh size of 5 μm and a filtration area of 3 cm ² for 4 hours (under these conditions, the filtration rate is 80 g / hr.cm ² ). The filtration pressure at that time is recorded on the recorder 7. The filtration pressure increasing rate is represented by an average value per hour for three hours excluding the first one hour after the start of ejection.

[0019]

The present invention will be described in more detail with reference to the following examples.

Examples 1 to 5, Comparative Examples 1 to 3 A method of mixing and polymerizing titanium oxide with a polyamide monomer (hereinafter abbreviated as "polymerization addition"), mixing polyamide pellets and titanium oxide, and melt-mixing with an extruder. Titanium oxide-containing polyamide pellets were obtained by a kneading method (hereinafter abbreviated as kneading addition). Examples 1 to 5 are methods according to the present invention, and Comparative Examples 1 to 3 are methods for comparison.

Each of the pellets was mixed with a titanium oxide-free pellet so that the titanium oxide concentration was 2% by weight, and the rate of increase of the filtration pressure was measured with a filtration pressure measuring device.

The pellets were dried in a vacuum to reduce the moisture content to 0.1.
%, And then passed through a 120-mesh filter sand using a pressure melter type spinning machine, and the pore size was 0.3 mm.
30 g / min. From a die having 20 discharge holes. Was discharged.

The spinning temperature at this time is 270 for nylon 6.
C., set to 290.degree. C. with nylon 66. After cooling in a chimney style, the spinning oil was applied.

Under these conditions, the take-up roller is driven at an initial speed of 10
00m / min. From 100 m / min. Speed up one by one,
The speed immediately before the single yarn started to be cut within 3 minutes was defined as the maximum leak yarn speed.

In the examples, the dry mill treatment refers to pulverization of titanium oxide by a jet mill, and the dispersant refers to 0.4% by weight of sodium polyacrylate based on titanium oxide.
And 0.15% by weight of sodium pyrophosphate. The results for nylon 6 are shown in Table 1, and the results for nylon 66 are shown in Table 2. In all of the examples of the present invention, the maximum leaking yarn speed was 3000 m / min. As described above, it is suitable for high-speed spinning. On the other hand, in the comparative example, the maximum yarn speed was 1500
m / min. High-speed spinning could not be performed below.

[0026]

[Table 1]

[0027]

[Table 2]

Examples 6 to 8, Comparative Example 4 Using the pellets of Examples 1, 2, 3 and Comparative Example 1,
Except for Example 1, it was mixed with a titanium oxide-free nylon 6 pellet obtained by a generally known method so that the titanium oxide content was 5% by weight. After drying in the same manner as in Example 1, using a 24-hole die, filter sand 120 mesh, spinning temperature 270 ° C., discharge amount 21 g / min. At the first godet roller speed of 1020 m / min. ,
The second god roller 3200 m / min. , Winder speed 3080 m / min. The spinning-drawing was performed directly under the winding conditions.

The results are shown in Table 3. In each of the examples, the yarn breakage was small, the strength and elongation of the obtained fiber were good, and it was suitable for a polymer for yarn production.

On the other hand, in the comparative example, yarn breakage occurred frequently, and continuous spinning was impossible. Further, the strength and elongation of the obtained fiber were insufficient.

[0031]

[Table 3]

Example 9 Using the pellets obtained in Example 2 as a core component and nylon 6 containing no titanium oxide as a sheath component, the core / sheath ratio was 35%.
/ 65 and a spinning speed of 4000 m / min. The spinning was carried out by a direct spinning and drawing method. Yarn breakage was small and the spinning property was good.

Further, the obtained fiber had good strength and elongation. Further, when four of these fibers were arranged to form a tubular knitted fabric, the knitted fabric was excellent in opacity.

[0034]

When the yarn is produced using the titanium oxide-containing polyamide pellet of the present invention, the yarn breakage during the yarn production is small,
And high-speed spinning becomes possible. Also, the strength and elongation of the fiber do not decrease.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an apparatus for measuring a rising speed of a filtration pressure in the present invention.

[Explanation of symbols]

 1: Chip hopper 2: Piston 3: Hot plate 4: Aluminum block heater 5: Gear pump 6: Filter 7: Recorder

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location D01F 6/60 301 D01F 6/60 301G

Claims (5)

[Claims] 1. A polyamide pellet comprising 3 to 70% by weight of titanium oxide and polyamide.
The polyamide pellet was diluted with a polyamide of the same type as the above-mentioned polyamide to a titanium oxide concentration of 2% by weight, and the filtration was performed at 285 ° C. with a 5 μm filter having a filtration rate of 80 g / hr · cm ^2. Polyamide pellets for yarn production having a pressure increasing rate of 9.8 MPa / hr or less. 2. The polyamide is nylon 6 or nylon 6.
6. The polyamide pellets for yarn production according to claim 1, wherein 3. The polyamide pellets for yarn production according to claim 1, wherein titanium oxide subjected to dry mill treatment is used. 4. A method for producing polyamide fibers, comprising spinning the polyamide pellets for yarn production according to claim 1. 5. A yarn production speed of 3000 m / min. The method for producing a polyamide fiber according to claim 4, characterized in that: