JP2011241530A - Sheath-core conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide fibers capable of economically obtaining products with cool feeling without applying bulky processing or silver plating.SOLUTION: Sheath-core conjugate fibers includes at its core portion 3 wt.% or more of titanium oxide with an average particle diameter of 0.8 to 1.8 μm. It is preferable that the sheath portion of the fiber is substantially free from titanium oxide with the average particle diameter of 0.8 μm or more. Further, it is preferable that the sheath portion contains 0.5 to 10 wt.% of titanium oxide with the average particle diameter of 0.4 μm or less, and that at the fiber cross section the bonding ratio of the core portion to the sheath portion is 5:1 to 2:3.

Description

  The present invention relates to a core-sheath type composite fiber made of a thermoplastic resin.

Many fabrics having a cool feeling have been proposed. For example, there are a method in which the shape and weaving of the fiber are devised to have a refreshing feeling due to the heat insulation effect, and a method in which infrared reflection is performed by covering the fiber surface with a cloth plated with silver.
Patent Document 1 discloses a specific bulky polyester multifilament crimp comprising a single filament containing 3% by weight or more of a sunscreen material as a whole and having a sunscreen material content of 0.8% by weight or less in the sheath. It is described that by using a yarn, the yarn contains a large amount of air, exhibits a heat insulation effect, and has a refreshing feeling.
Patent Document 2 discloses a fabric product having infrared reflectivity using a fabric material made of a fiber whose surface is coated with silver plating, a temporary tent type building, a roof material for a dome type building, and a leisure tent. It is described that the temperature inside the building can be adjusted by reflecting solar thermal infrared rays.

JP-A-8-158186 Japanese Patent Laid-Open No. 8-92842

However, in Patent Document 1, in order to make the yarn bulky, a process of supplying highly oriented undrawn yarn to a heat treatment machine, overfeeding, drawing and false twisting is required, resulting in high cost. .
In Patent Document 2, it is necessary to use a silver-plated cloth, which is costly due to the necessity of a silver plating process, and also has the disadvantage of being shielded from light by applying silver plating to the cloth. is there.

  In order to solve the above problems, the present invention has found that a refreshing feeling can be obtained by using a synthetic fiber using a specific amount of titanium oxide having a specific particle diameter on the side close to the center of the synthetic fiber. The present invention has been reached.

  That is, the gist of the present invention is a core-sheath type composite fiber containing 3% by weight or more of titanium oxide having an average particle diameter of 0.8 to 1.8 μm in the core. Among these, those containing substantially no titanium oxide having an average particle diameter of 0.8 μm or more in the sheath are preferable, and those containing 0.5 to 10% by weight of titanium oxide having an average particle diameter of 0.4 μm or less in the sheath. More preferably, in the fiber cross section, the joining ratio of the core part and the sheath part is more preferably 5: 1 to 2: 3.

  According to the present invention, a product having a refreshing feeling can be obtained at low cost without performing bulky processing or silver plating.

  The present invention is a core-sheath type composite fiber comprising a core part and a sheath part.

  The core-sheath type composite fiber of the present invention may be used as a staple or a filament, but is preferably used as a filament in order to obtain the effects of the present invention better.

  Various thermoplastic resins can be used for the core and the sheath. For example, polyamides such as polyester and nylon 6 can be mentioned. Among these, polyester is preferable from the viewpoint of the usage in which infrared rays of sunlight are reflected as described below. In particular, polyethylene terephthalate and a copolymer thereof are preferable from the viewpoint of cost and versatility.

The said core part contains 3 weight% or more of titanium oxide with an average particle diameter of 0.8-1.8 micrometers.
The average particle diameter is more preferably 0.8 to 1.5 μm, and even more preferably 0.9 to 1.2 μm. Further, the content of such titanium oxide is preferably 3% by weight or more, and more preferably 6% by weight or more. The upper limit is preferably about 20% by weight in consideration of spinning operability and fiber quality.

  In addition, the average particle diameter of this invention shows a weight average, for example, photographed using the transmission electron microscope (JEOL Co., Ltd. transmission electron microscope JEM-1230), and an automatic image processing apparatus (LUZEX AP (Nireco Corporation ))))), The volume-based horizontal equivalent diameter is measured, the specific gravity is calculated, and the weight average average molecular diameter can be obtained.

  Usually, titanium oxide used as a matting agent in synthetic fibers has an average particle size of about 0.3 μm, but in the present invention, by increasing the average particle size of titanium oxide to 0.8 μm to 1.8 μm, Since the infrared wavelength (0.8 to 3 μm) that is easily converted into thermal energy is reflected, a heat shielding effect can be exhibited. Most preferably, it is 0.8-1.5 micrometers.

That is, if the average particle diameter of titanium oxide is too large, it reflects a longer wavelength than the wavelength of 3 μm or less, which is an infrared wavelength that is easily converted into thermal energy, and a sufficient heat shielding effect cannot be obtained. If the average particle diameter of titanium oxide is too small, infrared rays of 3 μm or less that are easily converted into thermal energy will not be reflected, and visible light having a shorter wavelength will be reflected, and the heat shielding effect will not be sufficient. It is preferable to do.
Further, the average particle diameter of titanium oxide will be further described. As described above, among the wavelengths of light, the wavelength that is easily converted into thermal energy is 0.8 to 3 μm. Among them, a wavelength of 3 μm is most easily converted into thermal energy, but in order to reflect light having this wavelength, it is preferable to contain titanium oxide having a primary particle diameter of about 1.5 μm. However, in practice, it has a wavelength of 0.8 to 3 μm (width of 2.2 μm), and it is preferable that the particle size distribution of titanium oxide is widened. It is more preferable that the particle diameter of the titanium oxide is widely distributed within the range of the average particle diameter centering on the average particle diameter.

  It is preferable that the titanium oxide in the core has a primary particle size of 0.5 to 2.0 μm.

  The crystal structure of the titanium oxide is preferably a rutile type. In general, titanium oxide used as a matting agent for fibers is generally anatase type.

Next, the sheath part of the core-sheath composite fiber of the present invention will be described.
The sheath is preferably substantially free of titanium oxide having an average particle size of 0.8 μm or more.
It is preferable that the said sheath part contains the titanium oxide of the particle diameter normally used for a fiber.
In addition, the core portion contains a large amount of titanium oxide having an average particle diameter of 0.8 to 1.8 μm, and reflects the wavelength in the infrared region of 3 μm or less. However, since it is difficult to reflect visible light, the whiteness decreases. . In order to obtain a desired whiteness, it is preferable that the sheath part contains 0.5 to 10% by weight of titanium oxide having an average particle diameter of 0.4 μm or less. Among these, 1 to 9% by weight is preferable, and 1 to 2% by weight is particularly preferable.

  In the fiber cross section of the core-sheath composite fiber of the present invention, the bonding ratio between the core part and the sheath part is preferably an area ratio of 5: 1 to 2: 3, more preferably 5: 1 to 2: 1. . That is, if the ratio of the core portion is too large, a large amount of titanium oxide having a large average particle diameter is contained, which may lead to a decrease in yarn quality or difficulty in winding during spinning. In addition, when the ratio of the sheath portion is too large, the portion containing titanium oxide having a large average particle diameter decreases, the portion that does not reflect infrared rays having a wavelength of 3 μm or less that tends to become thermal energy increases, and the heat shielding effect is small. Therefore, the above range is preferable.

  In the fiber cross section, the core is preferably not exposed to the outside.

  The amount of titanium oxide having an average particle size of 0.8 to 1.8 μm with respect to the entire composite fiber is preferably 2 to 20% by weight, more preferably 4 to 20% by weight, and further preferably 6 to 20% by weight. If it is less than 2% by weight, the amount of titanium oxide having an average particle diameter of 0.8 to 1.8 μm that contributes to the reflection of infrared rays having a wavelength of 3 μm or less is small, and there is a possibility that the heat shielding effect is not exhibited. On the other hand, if it exceeds 20% by weight, the permeability in the filament manufacturing process and the subsequent process is extremely deteriorated, and the strength may be lowered. For example, traveler wear may occur in the drawing process, and thread breakage may occur.

  The fineness of the core-sheath composite fiber of the present invention is not particularly defined, but the total fineness is preferably about 22 to 110 dtex, more preferably 33 to 110 dtex, and still more preferably 44 to 110 dtex. The number of filaments is not particularly limited, but is preferably about 12 to 48. The single yarn fineness is preferably 1 to 5 dtex. In addition, when using for a roll curtain, the total fineness of 50-110 dtex and the single yarn fineness of 1-5 dtex are preferable.

  The breaking strength of the core-sheath type composite fiber of the present invention is preferably 2.5 cN / dtex or more, more preferably 3.0 cN / dtex or more.

  The core-sheath type composite fiber of the present invention can be used for various purposes after being knitted or woven. For example, in the case of apparel use, the cover factor is 1000 to 2800, and when it is used for a roll curtain, the effect of the refreshing feeling of the present invention is obtained when the cover factor is plain and the cover factor is 1800 to 2400 and the see-through is 1000 to 1500. Cheap.

Next, the method for producing the core-sheath composite fiber of the present invention will be exemplified.
The fiber-forming polymer that forms the core is made to contain titanium oxide having an average particle size of 0.8 to 1.8 μm. Although the method of making it contain is not specifically limited, For example, the method of knead | mixing and kneading titanium oxide with a biaxial kneader with a thermoplastic resin is mentioned. Further, it may be added during polymerization.
The polymer forming the sheath is made to contain about 0.3 μm of titanium oxide. Although this method is not particularly limited, a method of adding at the time of polymerization is useful.
Each of the polymers containing the two types of titanium oxide is melted with an extruder having a temperature equal to or higher than the melting point of the polymer, preferably 20 ° C. higher than the melting point. The molten polymer is passed through a die that forms a core sheath, and the polymer of the core-sheath cross section is extruded from the hole on the surface of the die to form a multifilament. The multifilament is cooled with cold air, oiled and wound. The winding method may be winding with a normal spinning machine, and the winding speed is not particularly limited, but it is preferable to wind at a winding speed of 700 m / min to 2000 m / min. The wound yarn is stretched three times by applying heat at 75 ° C., for example, and set by applying heat at 140 ° C. to obtain a core-sheath composite fiber. As a suitable stretching temperature, in the case of polyethylene terephthalate, 70 to 80 ° C., the stretching ratio is preferably 2.8 to 3.5 times, and the heat setting temperature is preferably about 120 to 150 ° C.
Each of the polymers containing two types of titanium oxide is melted with an extruder having a temperature higher than the melting point of the polymer, preferably 20 ° C. higher than the melting point, and passed through a die that forms a core sheath. The multifilament extruded as a polymer having a sheath cross section may be cooled with cold air and oiled, and then heated and stretched again without being wound, and then wound and then heat set.

Measurement and evaluation were carried out by the following methods.
<Coolness>
A normal semi-dal polyester yarn 56dtex / 24f was used for the warp yarn, and a two-drawn yarn obtained by aligning the two polyester yarns obtained for the weft yarn was woven in a plain weave to obtain a sample (product of the present invention). : 110 pieces / 2.54 cm, latitude density: 77 pieces / 2.54 cm). A control product was obtained by weaving in the same manner except that two normal semi-dal polyester yarns 56 dtex / 24f were used as weft yarns. Next, one surface of the hexahedron of the heat insulation box is made of glass and the sample is held in the glass, and a halogen lamp (500 W × 2 lamps installed) is placed at a position 45 ° above the glass surface and 60 cm away horizontally. The temperature inside the box was compared between the product of the present invention and the control product, and the difference in temperature rise in the box after 60 minutes (the temperature rise of the control product-the temperature rise of the product of the present invention) was determined. The one with the larger temperature difference is superior in coolness.
<Average particle size>
Taking a photograph using a transmission electron microscope (Transmission Electron Microscope JEM-1230 manufactured by JEOL Ltd.), measuring the volume-based horizontal equal diameter with an automatic image processing device (LUZEX AP (manufactured by Nireco Corporation), The specific gravity was calculated and the average particle diameter of the weight average was obtained.
<Threading property>
If the process passability was good, it was evaluated as ◯, if the process passability was slightly bad, Δ, and if the yarn could not be produced, it was rated as x.

Example 1
The core is a polyester resin containing 12% by weight of titanium oxide having an average particle size of 1.0 μm (rutile type, the particle size is distributed in a substantially normal distribution in the range of 0.5 to 2.0 μm), and the sheath is the average particle size A polyester resin containing 6% by weight of 0.3 μm titanium oxide (anatase type) is used, and each core is melted at 290 ° C., and the core-sheath ratio is 2: 1 from the die that becomes the core sheath of 48 filaments. It discharged with the discharge hole which becomes. The discharged yarn was cooled with cold air, oiled, and wound at a spinning speed of 1500 m / min. Thereafter, the film was drawn at 75 ° C. and set at 135 ° C. to obtain a drawn yarn of 56 dtex / 24f. The processability of yarn production was good.
As a result of the evaluation of the cool feeling described above, the temperature in the box was 2 ° C. lower than the control product, and the cool feeling was excellent.

(Example 2)
A drawn yarn was obtained in the same manner as in Example 1 except that the amount of titanium oxide in the sheath was 1.3% by weight. Like the example 1, it was excellent in coolness. Moreover, the thing of Example 1 was excellent in whiteness.

(Examples 3-5, Comparative Example 1)
A drawn yarn was obtained in the same manner as in Example 2 except that the amount of titanium oxide in the core was changed.
The core having titanium oxide within the scope of the present invention was excellent in coolness. When the amount of titanium oxide in the core portion was 9% by weight, it was particularly excellent in cool feeling like 12% by weight. Comparative Example 1 in which the titanium oxide in the core part was 2% by weight was inferior in coolness as compared with the Example product.

(Comparative Examples 2 and 3)
A drawn yarn was obtained and woven in the same manner as in Example 2 except that the average particle size of titanium oxide in the core was changed. Those having an average particle size of 0.3 μm and 0.4 μm were inferior in coolness compared to Example 2.

  Examples 1-5, average particle diameter of core part and sheath part of Comparative Examples 1-3, weight%, ratio of titanium oxide having an average particle diameter of 0.8-1.8 μm in the fiber, coolness, and yarn production Table 1 shows.

(Examples 6 to 9)
A drawn yarn was obtained in the same manner as in Example 1 except that the core-sheath composite ratio was changed as shown in Table 2. Table 2 shows the coolness and the yarn production.

Examples 1, 6, and 7 having a core-sheath composite ratio of 2: 1 to 5: 1 were particularly excellent in both coolness and yarn-forming properties. Example 8 having a core-sheath composite ratio of 8: 1 was slightly inferior to the yarn-making property although it was extremely cool. The core / sheath composite ratio of 2: 3 is good in both coolness and yarn-making property, but the coolness is better in Examples 1 and 6-8.
As described above, the example product of the present invention has a good processability for yarn production as compared with the comparative product, can suppress the temperature rise in the box, has excellent coolness, and has a refreshing feeling. Was obtained.

  The core-sheath type composite fiber of the present invention can be used as an interior interior material such as a roll curtain, and can suppress an increase in indoor temperature compared with a roll curtain of a conventional synthetic fiber product. Is also connected. In addition, when used outdoors as clothes, the temperature rise is suppressed more than that of conventional clothes, and the coolness is excellent and a refreshing feeling can be brought about. Furthermore, it can be suitably used as a parasol, a hat, a glove, a tent, an agricultural net, a building material for a roof or a wall, etc., for applications that require heat insulation and coolness.

Claims (4)

A core-sheath type composite fiber containing 3% by weight or more of titanium oxide having an average particle diameter of 0.8 to 1.8 μm in the core part. The core-sheath-type conjugate fiber according to claim 1, wherein the sheath part substantially does not contain titanium oxide having an average particle diameter of 0.8 µm or more. The core-sheath type composite fiber according to claim 1 or 2, wherein the sheath part contains 0.5 to 10% by weight of titanium oxide having an average particle size of 0.4 µm or less. The core-sheath type composite fiber according to any one of claims 1 to 3, wherein a joining ratio between the core part and the sheath part is 5: 1 to 2: 3 in the fiber cross section.