JP2008184725A - Dope-dyed nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dope-dyed nonwoven fabric exhibiting sufficient coloring effect and improved in fiber splittability and process stability. <P>SOLUTION: The dope-dyed nonwoven fabric includes a conjugate fiber splittable by flaking and of two components composed of a polyamide polymer component and a polyester polymer component, wherein 0.5-30 wt.% carbon black having an average primary particle diameter of 10-50 nm is contained in only one of the components based on the weight thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an original nonwoven fabric colored with carbon black, and more specifically, from a split-divided composite fiber composed of two components, a component made of a polyamide polymer and a component made of a polyester polymer. It is related with the original nonwoven fabric.

  In the past, fabrics with high density and fine touch and excellent drape properties have been put on the market, and fineness fibers are often used to obtain such fabrics. As a means for obtaining a fine fiber, a method of producing a fine fiber from the beginning and a fiber obtained as a composite fiber from two different polymers are divided and extracted through a process such as extraction. The method is taken. However, from the viewpoint of rationalization of the process and process condition, a method is mainly used in which a composite fiber that can be thinned into fine fibers by the latter method is manufactured and made into a fabric, and then the fiber is thinned. For example, in JP-A-4-300311, JP-A-10-53948, etc., a long-fiber non-woven fabric made of peeled split-type composite fibers that does not require extraction equipment and an extraction process is treated with a high-pressure water flow machine. There has been proposed a method of obtaining an ultrafine fiber nonwoven fabric by dividing an exfoliation split type composite fiber into ultrafine fibers. However, these methods have a limit in the division performance, and there is also an upper limit in the non-woven fabric basis weight that can be reliably divided. In particular, when a non-woven fabric made of ultrafine fibers is used as artificial leather, a material having a large basis weight is required, and therefore a method that can be easily made ultrafine is desired.

  On the other hand, various artificial leather manufacturing techniques have been developed. By using a nonwoven fabric made of ultrafine fibers as a base fabric, it has recently become possible to obtain a texture similar to natural leather. The cut surface has a disadvantage that it differs from the color of the surface layer with silver. In particular, when a black surface layer is used, if the cut surface is white, the aesthetics are impaired, and it is necessary to impart a color to the nonwoven fabric itself used as the base fabric. In order to compensate for these drawbacks, for example, a method of dyeing a fiber or a method using an original yarn can be considered, but the subsequent process is complicated in the dyeing process, and the method using the original yarn reduces the strength of the fiber. And problems such as a decrease in process stability occur.

JP-A-4-30031 JP-A-10-53948

  The present invention has been made in view of the above-described background art, and an object thereof is to provide an original nonwoven fabric that exhibits a sufficient coloring effect and has improved fiber splitting property and process stability.

  As a result of intensive studies, the inventors of the present invention are non-woven fabrics composed of a split-divided composite fiber composed of two components, a component composed of a polyamide polymer and a component composed of a polyester polymer, and one of the components The above-mentioned object can be achieved by the original nonwoven fabric characterized in that only 0.5 to 30% by weight of carbon black having an average primary particle size of 10 to 50 nm is contained on the basis of the weight of the component. I found it.

  The original nonwoven fabric of the present invention can be obtained with good process stability by incorporating carbon black into one component of the peelable split composite fiber constituting the nonwoven fabric. Even if the basis weight of the nonwoven fabric is large, it can be efficiently divided and made into ultrafine fibers, so that an original nonwoven fabric composed of ultrafine fibers having excellent strength can be obtained easily. In addition, the original nonwoven fabric obtained in this manner can be suitably used for artificial leather base fabric applications that require both physical properties such as aesthetics and strength.

  Hereinafter, embodiments of the present invention will be described in detail. The release-dividing composite fiber used in the present invention is not particularly limited as long as it is composed of a fiber-forming polyester polymer and a fiber-forming polyamide-based polymer and can be separated into each component by mechanical treatment or the like. . Examples of polyamide polymers preferably used include nylon-6, nylon-66, nylon-610, nylon-11, nylon-12, and the like, while polyester polymers include, for example, polyethylene terephthalate, polytriethylene. Examples thereof include ethylene terephthalate, polybutylene terephthalate, and copolyesters containing these as main components. Among these, a combination of nylon-6 / polyethylene terephthalate is preferable from the viewpoint of processability and cost.

  The composite form of the peelable split composite fiber is a composite form in which at least a part of the interface between the polyester polymer and the polyamide polymer reaches the fiber surface, and can be separated into each component by mechanical treatment etc. If it is, it will not specifically limit, However, It is desirable from the point of a splittability that the one component mutually is divided | segmented into the predetermined number by the other component. Among these, a cross-sectional shape in which one component is arranged radially between other components is preferable. In this way, the number of divisions of the peeled split composite fibers arranged radially can be arbitrarily set by a method in which two components are melted and then merged in the die, taking into consideration the single yarn fineness of the composite fiber before splitting. However, 4 to 48, particularly 8 to 24 divisions are particularly preferable from the viewpoints of yarn-making properties, easiness of division and the effects thereof. In the present invention, the average primary particle size of carbon black contained in the ultrafine fibers needs to be 10 to 50 nm. When the average primary particle size is less than 10 nm, it becomes difficult to prevent secondary aggregation, and disadvantages such as reduction in strength occur. On the other hand, when the average primary particle size exceeds 50 nm, the formation of secondary aggregation decreases, but the darkness of the ultrafine fibers decreases. A more preferable range is 12 to 30 nm.

  In addition, the carbon black needs to be contained in only one of the two types of polymer components constituting the peelable split composite fiber. If it is contained in both, the strength of the nonwoven fabric will be significantly reduced, and process stability will be lowered, for example, foreign matter tends to adhere to the periphery of the holes for discharging the polymer component during spinning. Further, the splitting property is lowered in the splitting process for generating ultrafine fibers.

  Furthermore, the content of carbon black with respect to the fibers needs to be 0.5 to 30% by weight. If it is less than 0.5% by weight, a sufficient coloring effect cannot be obtained, and if it exceeds 30% by weight, the strength of the non-woven fabric after ultrathinning is reduced. A preferable range of the content is 1 to 15% by weight.

  As a method of mixing carbon black with the above-described separation-dividing composite fiber, a method of containing carbon black dispersed directly or in a support medium in a molten resin used as a raw material of the fiber, a resin pellet was mixed with carbon black. Examples thereof include a method of fiberizing by melt spinning or the like, and a method of mixing a master batch containing carbon black at a high concentration with a resin pellet and fiberizing by melt spinning or the like. Among these, the method of mixing carbon black with a masterbatch is preferably used in terms of production cost.

  In addition, the composite ratio with respect to the whole of one component of the above-described peelable split composite fiber is in the range of 30 to 70% by weight from the viewpoint of the spinnability of the composite fiber and the formation of split ultrafine fibers after forming the long fiber nonwoven fabric described later, particularly A range of 40-60% by weight is suitable. When outside this range, it is difficult to adjust the viscosity balance of both polymers, section defects during spinning are likely to occur, and the splitting efficiency when splitting ultrafine fibers is easily reduced. The cross-sectional shape of the entire peelable split composite fiber is arbitrary, such as a round cross-sectional shape, a multi-leaf cross-sectional shape, and a polygonal shape, and may have a hollow portion. This is preferable because the interfacial length can be reduced, and the separation of the separation is improved.

  The single yarn fineness after the separation treatment is suitably in the range of 0.01 to 0.06 dtex, and the one less than 0.01 dtex is difficult to produce. On the other hand, if it exceeds 0.06 dtex, As the cover factor decreases, the spots tend to increase, and the texture tends to decrease.

  Further, within the range not impairing the object of the present invention, either titanium oxide, aluminum oxide, silicon oxide, calcium carbonate, mica, fine metal powder, organic pigment, inorganic pigment or the like is selected from polyamide polymer and polyester polymer. These additives may be added to the polymer, and these additives have the effect of increasing or decreasing the melt viscosity of the polymer as well as the effect of coloring the thermoplastic polymer, and are effective in adjusting the fiber cross-sectional shape.

  In the present invention, the above-described exfoliated split type composite fiber is captured as a web on the porous collecting surface while weaving the drawn yarn that has been wound up by the spunbond method or by spinning / drawing with a high-speed traction fluid. The web is made by a known method such as collecting. Among these, the spunbond method in which the yarn spun from the base is pulled at high speed and is injected and collected on the collection net is particularly preferable from the viewpoint of productivity. Here, the speed of high-speed towing is suitably in the range of 2000 to 8000 m / min, particularly in the range of 3000 to 6000 m / min, and the composite long fiber discharged from the spinneret is within the above range by an ejector or air soccer. Tow at high speed. The composite long fiber thinned by high-speed traction is collected on a collection net while being opened. At that time, it is preferable to charge the fibers by a conventionally known method such as charging by corona discharge or contact charging in order to obtain a web having more excellent uniformity. When collecting the composite long fibers on the net, it is also possible to mix other short fibers or to laminate and mix other long fibers. The mixed cotton text is not particularly limited as other fiber materials to be laminated and mixed. For example, regenerated fibers such as rayon, semi-synthetic fibers such as acetate, natural fibers such as wool, nylon-6, nylon-66, etc. Polyamide fibers such as polyethylene fibers, polyethylene fibers such as polyethylene terephthalate and polybutylene terephthalate, polyolefin fibers such as polyethylene and polypropylene, and the like can be arbitrarily selected and used. Of course, the fiber shape and the like are not limited, and any of a core-sheath type composite fiber, a peel-splitting type composite fiber combining two or more kinds of thermoplastic resins, and other fibers having an irregular cross-sectional shape can be used. . The long fiber web obtained in this manner is formed by laminating a plurality of sheets as required, or independently, preliminarily thermally bonded as necessary, and once wound up or continuously. A tangled process such as a punch process is applied to obtain a long fiber nonwoven fabric.

  In the present invention, it is necessary to treat the long-fiber nonwoven fabric subjected to the above-described entanglement treatment to divide and make the exfoliation-divided composite continuous fiber fine, but the division method can surely perform the division and ultra-thinning. Any method may be used, and the method is not particularly limited. A plurality of methods may be combined. For example, examples of the mechanical division treatment method include a method of pressurizing between rollers, a method of performing ultrasonic treatment, a method of applying an impact, and a method of stagnation treatment. A method using a hitting type grinder is the most effective and preferable. In addition, the sheet-like object hitting probe referred to here is one that can efficiently apply a breaking force in the thickness direction of the sheet, and can efficiently perform split ultrafine fiber separation of the split split composite fiber. it can. On the other hand, the method using only high-pressure columnar water flow treatment or impact is not preferable because the separation and division is difficult when the nonwoven fabric has a large basis weight, but it can be combined with other divided ultrafine fiber forming methods. .

  In order to further improve the texture after dividing the nonwoven fabric into fine pieces, it is preferable to perform shrinkage heat treatment subsequent to the division treatment, so that the heat is applied before the fiber division is performed. It is preferable to avoid the processing method. In addition, it is preferable to avoid the split processing method using a high-pressure water flow because the entangled state formed by needle punching or the like is easily broken.

  The ultrafine fiber nonwoven fabric produced by the method described above is preferably subsequently subjected to shrinkage heat treatment, particularly shrinkage heat treatment in a relaxed state, and the area shrinkage rate is in the range of 5 to 60%, particularly 10 to 50%. A range is preferred. By doing so, coarse voids inside the long fiber nonwoven fabric are eliminated, and a uniform and dense structure can be generated. Note that one component of the separation-separation-type composite continuous fiber is preferably one having a larger heat shrinkage rate than the other component. In this case, the difference in heat shrinkage rate in 95 ° C. warm water is 5 to 60%. It is preferable that it is the range of 10 to 50% especially.

The heat shrinkage referred to here is calculated from the shrinkage obtained by shrinking long fibers in warm water at 95 ° C. for 30 minutes under a load of 0.005488 cN / dtex (0.56 g / tex) by the following equation. Is done.
Shrinkage rate = ((length before shrinkage treatment−length after shrinkage treatment) / (length before shrinkage treatment)) × 100 (%)

On the other hand, the area shrinkage rate is calculated by the following equation.
Area shrinkage rate = ((long fiber nonwoven fabric area before shrinkage−long fiber nonwoven fabric area after shrinkage) / (long fiber nonwoven fabric area before shrinkage) (%) × 100 (%)

  Moreover, the shrinkage heat treatment in a relaxed state here refers to shrink heat treatment while the long fiber nonwoven fabric is advanced in one direction under an overfeed rate of 3 to 30%. In that case, from the viewpoint of a relaxed state, it is preferable to keep the side edge part of the long-fiber nonwoven fabric orthogonal to the advance direction of the long-fiber nonwoven fabric in a non-gripping state. The overfeed rate may be determined according to the target area shrinkage rate. However, it is preferable to set the overfeed rate in the range of 3 to 30% because an area shrinkage rate of 5 to 60% is easily achieved.

  The ultrafine fiber nonwoven fabric obtained by the production method of the present invention described above is used for artificial leather base fabrics and clothing, interior materials, interior materials and other industrial materials, industrial wipers and wipes such as wiping cloth, It can be preferably used for filter applications such as bag filters and filter cloths, and medical hygiene materials. Moreover, when the thing with a thin weight is required, it can also produce efficiently by slicing the obtained thing with a high weight.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the part and% in an Example are a basis of weight, and each measured value was calculated | required according to the following method, respectively, and unless otherwise indicated, a measured value measured 5 points | pieces. The average value.

(1) Intrinsic Viscosity of Polyester Polymer It was measured at 35 ° C. using o-chlorophenol as a solvent.
(2) Intrinsic viscosity of polyamide polymer: Measured at 35 ° C. using m-cresol as a solvent.
(3) Polymer discharge state During the composite spinning, the discharge state of the polymer discharged from the spinneret was observed, and the discharge state was rated according to the following criteria. Observation was made 12 hours after the start of the composite spinning.
Level 1: The discharged yarn is running stably with a substantially constant flow line.
Level 2: There are small bends, repeated bends, swiveling, etc. in the discharged yarn.
Level 3: The discharged yarn is greatly bent, repeatedly bent, or swiveled. Part of the polymer is in contact with the spinneret surface, and the yarn breakage occurs frequently.
(4) Number of splits The split ratio of the peelable split composite fibers was measured by taking a cross section of the nonwoven fabric at 200 times with an electron microscope, measuring the cross section of 100 fibers, and the total area and undivided (completely split) The difference in the cross-sectional area of the filaments (not including, for example, those divided into about two or three) is divided by the total area. The larger the division ratio, the better the division.
(5) Strength of the composite fiber (undivided) The composite fiber is gripped by a tensile tester Tensilon manufactured by Shimadzu Corporation with a sample length of 20 mm (grip spacing 20 mm), stretched at a tensile speed of 20 mm / min, and the load value at the time of cutting is determined. The strength was measured by dividing this by the total fineness of the composite fiber.
(6) Fineness of ultrafine fibers The fineness of undivided composite fibers was measured with a fineness measuring instrument (SERCH Co. LTD, model DC-21) at a test length of 2.5 cm and a load of 1 g, and the cross section of the composite fibers was measured. It was obtained by dividing by the number of divisions.
(7) Thickness of non-woven fabric A thickness measuring device (PEACOCK model H manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.) was used, and measurement was performed with a load of 1.764 N (180 g) per 1 cm ^{2 of} the sample.
(8) Strength of non-woven fabric The test piece after the split treatment with a width of 2 cm and a length of 9 cm was sampled with respect to the longitudinal direction and the transverse direction of the non-woven fabric, the test piece was gripped with a chuck, the chuck interval was 5 cm, the tensile speed was 5 cm The strength at break was determined by converting the average strength in the longitudinal direction and the transverse direction per width of 1 cm and per sample weight of 100 g / m ² .

[Example 1]
Nylon-6 having an intrinsic viscosity of 1.2 was used as the polyamide polymer. A master batch pellet containing 24% by weight of carbon black having Ny-6 as a base resin and an average primary particle size of 14 μm (measured by an electron microscope at 3000 times), and the same Ny-6 pellet as described above, A mixed pellet was prepared by mixing so that the carbon black was 3% by weight with respect to the whole. On the other hand, a polyethylene terephthalate (PET: manufactured by Teijin Fibers Limited) pellet having an intrinsic viscosity of 0.64 was prepared as a polyester polymer. The above mixed pellets containing master batch pellets and PET pellets are melted separately in an extruder, and then merged in the die, and discharged from a hollow die with a discharge rate per single hole of 2 g / min. After high-speed traction with an air pressure of 343 kPa (3.5 kg / cm ² ), a high voltage application treatment is performed at −30 kV, the filament is opened, and the 16-part multilayer laminated section shown in FIG. As a web composed of peeled split composite long fibers (weight ratio of both components is 48/52, single yarn fineness is 4.1 dtex), the web was collected with a gathering net conveyor with a basis weight of 40 g / m ² and a width of 1 m.

The obtained web is continuously lightly bonded with an embossing calendar at 100 ° C above and below, 12 layers of this web are laminated on a cross layer, entangled with a needle punch, immersed in water, and lightly mangled. After squeezing, the composite fiber was split into ultrafine fibers using a sheet-like material striking-type squeezing machine. The obtained nonwoven fabric had a basis weight of 480 g / m ² and was well divided up to the inner layer, and was a soft nonwoven fabric excellent in texture. The results are shown in Table 1.

[Example 2]
As a polyester polymer, a master batch pellet containing 20% by weight of carbon black having an average primary particle size of 14 nm with respect to polyethylene terephthalate (PET) having an intrinsic viscosity of 0.64 is carbon black. A non-woven fabric was obtained in the same manner as in Example 1 using Ny-6 having an intrinsic viscosity of 1.2 as a polyamide polymer. The results are shown in Table 1.

[Examples 3-4, Comparative Examples 1-4]
A non-woven fabric was prepared in the same manner as in Example 1, except that the carbon black content and the primary particle size used in the masterbatch were variously changed. Table 1 shows the physical properties of the obtained nonwoven fabric.
As is clear from Table 1, in Examples 1 to 4, even when the fabric weight is high, the split ultrafine fibers are effectively advanced, the strength is high, and the nonwoven fabric excellent in the texture is obtained with good process stability. . On the other hand, in Comparative Example 1, which is out of the scope of the present invention, the carbon black content was small and the process stability and physical properties were good, but sufficient colorability was not obtained. In addition, Comparative Example 2 having too much content and Comparative Example 4 having a large primary particle size of carbon black have low strength, and Comparative Example 3 in which carbon black is contained in both components reduces the splitting property. The process stability was greatly inferior.

[Example 5]
The nonwoven fabric obtained in Example 1 was immersed in a hot water pass at 850 ° C. for 2 minutes and subjected to shrink heat treatment. The obtained shrinkable nonwoven fabric has an area shrinkage ratio of 20%, has a dense structure, exhibits a soft and solid texture, and is extremely suitable as an artificial leather base fabric. Was black and excellent in aesthetics as an artificial leather.

[Comparative Example 5]
The same procedure as in Example 4 was performed except that the nonwoven fabric obtained in Comparative Example 1 was used instead of the nonwoven fabric obtained in Example 1. Although the obtained shrink nonwoven fabric had a good texture, the cut surface was white and when used as artificial leather, it was greatly inferior in aesthetics.

  According to the peelable split composite fiber of the present invention, a nonwoven fabric can be obtained with good process stability by containing carbon black as one component. Further, even if the basis weight of the nonwoven fabric is large, it is possible to efficiently produce divided ultrafine fibers, and it is possible to provide an original ultrathin fiber nonwoven fabric that is easy and excellent in strength. Therefore, the nonwoven fabric obtained in this way can be suitably used for artificial leather base fabric applications that require both physical properties such as aesthetics and strength, and its industrial value is extremely high.

It is the schematic which shows an example of the cross section of the peeling separation type composite fiber which comprises the nonwoven fabric of this invention.

Explanation of symbols

1 First component (polyamide polymer)
2 Second component (Polyester polymer)

Claims (3)

  A non-woven fabric made of a split split-type composite fiber composed of two components, a component made of a polyamide polymer and a component made of a polyester polymer, and the average primary particle diameter is 10 to 10 only in one of the components. An original non-woven fabric containing 50 to 30% by weight of carbon black of 50 nm based on the weight of the component.   The original nonwoven fabric according to claim 1, wherein either one of the components is exposed on the surface of the peelable split composite fiber.   The raw nonwoven fabric according to claim 1 or 2, wherein the separation-dividing long fibers are divided into ultrafine fibers having a single yarn of 0.01 to 0.6 dtex.

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