JP2007321296A - Method for producing ultra fine filament nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an ultra fine filament nonwoven fabric, by which the opening property of peel-division type conjugated filaments comprising a thermoplastic elastomer and a polyamide-based polymer can be improved to easily produce the high quality ultra fine filament nonwoven fabric having excellent uniformity. <P>SOLUTION: This method for producing the ultra fine filament nonwoven fabric is characterized by forming a filament nonwoven fabric, for example, by a spun bond method, from peel-division type conjugated filaments comprising a polyamide-based polymer and a thermoplastic elastomer containing a polybutylene terephthalate-based polyester in an amount of 5 to 30 wt.%, and then subjecting the filament nonwoven fabric to a division treatment to divide the peel-division type conjugated filaments into ultra fine filaments. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for easily producing an excellent-quality ultra-fine long-fiber nonwoven fabric by improving the spreadability of a peelable split composite long fiber comprising a thermoplastic elastomer and a polyamide-based polymer.

Conventionally, non-woven fabrics made of long fibers have higher strength than non-woven fabrics made of short fibers, and the manufacturing method does not require a series of large-scale equipment such as a raw cotton supply unit, a fiber opening device, a card machine, and a crosslay machine. Due to its advantages, it is widely used for civil engineering and agriculture, as well as for life-related materials and clothing. In recent years, various proposals have been made in which the constituent fibers are made thinner to improve the quality and performance based thereon.
For example, in Patent Document 1, Patent Document 2, and the like, in a long-fiber nonwoven fabric by a spunbond method of direct spinning type, which is a typical method for producing a long-fiber nonwoven fabric, a constituent fiber is a split split-type composite long fiber, and a high pressure There has been proposed a method of obtaining an ultrafine fiber nonwoven fabric by treating with a water flow machine or the like to divide the peelable split composite fiber into ultrafine fibers.
On the other hand, non-woven fabric made of elastomer is excellent in terms of texture such as softness and resilience due to its low initial tensile tension, and is used for clothing and hygiene applications, such as polyurethane, polyester-based elastomer, olefin-based elastomer, etc. There has been proposed a method of forming a non-woven fabric from the above raw materials by a spunbond method or a melt blow method (see Patent Documents 3 to 5). However, the melt-blowing method is capable of making ultrafine fibers, which is superior in that it is easy to obtain a non-woven fabric with further softness, but the productivity is greatly inferior to that of the spunbond method. Yes. On the other hand, the spunbond method is superior in productivity to the melt blow method, but not only is it difficult to obtain an ultra-thin fiber non-woven fabric, but it is easy to cause agglutination when the fibers are thinned. It is difficult to obtain a spread nonwoven fabric, and there is a problem that the uniformity is remarkably inferior as compared with a nonwoven fabric obtained from a crystalline resin such as polyester or polyolefin.
In order to improve such a problem of sticking, for example, Patent Document 6 proposes a method of adding a polyolefin and an inorganic fine powder to a polyester elastomer and melt-blowing. However, even if this method is applied to the spunbond method as it is, it is still difficult to obtain an ultrafine long-fiber nonwoven fabric because it is difficult to make ultrafine fibers.
JP-A-4-30031 JP-A-10-53948 JP-A-57-95362 Japanese Patent Publication No.63-31581 JP-B-1-47578 Japanese Patent Laid-Open No. 5-140852

  The present invention has been made against the background of the above-described prior art, and its purpose is to improve the opening property of the peelable split composite long fiber composed of a thermoplastic elastomer and a polyamide-based polymer, thereby making it hydrophilic and uniform. An object of the present invention is to provide a method capable of easily producing an excellent high-quality ultra-fine long-fiber nonwoven fabric.

As a result of intensive studies to achieve the above object, the present inventors have found that polybutylene terephthalate-based polyester is 5-30 on the thermoplastic elastomer side of the peelable split-type composite continuous fiber composed of a thermoplastic elastomer and a polyamide-based polymer. Mixing by weight% improves the fiber spreadability and improves the uniformity of the nonwoven fabric, and by treating the resulting nonwoven fabric with, for example, a high-pressure water flow machine, ultrafine fibers including ultrafine fibers made of an elastomer The present inventors have found that a nonwoven fabric can be easily obtained, and have reached the present invention.
Thus, according to the present invention, “a long-fiber nonwoven fabric composed of peel-divided long fibers composed of a thermoplastic elastomer containing 5 to 30% by weight of a polybutylene terephthalate-based polyester and a polyamide-based polymer is subjected to a split treatment. There is provided a method for producing an ultra-fine long-fiber nonwoven fabric, characterized in that the exfoliated split composite long fibers are made into ultra-fine fibers.

  According to the production method of the present invention, since the polybutylene terephthalate polyester is blended with the thermoplastic elastomer used as one component of the split split-type composite long fiber, the long fiber nonwoven fabric is produced by the spunbond method or the like. In this case, a long-fiber nonwoven fabric excellent in uniformity without unevenness between the fibers can be obtained. Therefore, by dividing this by a mechanical method or the like, it is possible to easily provide an ultra-thin fiber nonwoven fabric excellent in uniformity without texture and unevenness.

  In the present invention, a thermoplastic elastomer containing a polybutylene terephthalate-based polyester and a polyamide-based polymer are first composited in a release-separated mold to obtain a long-fiber nonwoven fabric composed of release-divided composite long fibers. Here, the method for forming the long-fiber nonwoven fabric is not particularly limited, and any conventionally known method can be adopted. However, the spunbond method is particularly preferable because it is simple and has good productivity.

  As the composite form of the peelable split composite long fiber, a composite form in which at least a part of the joining interface between the thermoplastic elastomer polymer containing polybutylene terephthalate polyester and the polyamide polymer reaches the fiber surface is mechanical. Although it will not specifically limit if it can peel-separate into each component by a process etc., It is desirable from the point of a splitting property that the one component mutually is divided | segmented into the predetermined number by the other component. In particular, a cross-sectional shape in which one component is arranged radially between other components as shown in FIG. 1 is preferable. Further, as shown in FIG. 2, a cross-sectional shape in which a predetermined number of one component and the other component are stacked in parallel may be used.

  Further, the ratio of the arc length (A) of the thermoplastic elastomer to the arc length (B) of the polyamide polymer occupying the circumference of the fiber cross section (hereinafter referred to as polymer component arc length ratio (A / B)) is 0. It is preferable to arrange the two components in a range of 1 to 2.0, particularly 0.2 to 1.5. When this polymer component arc length ratio (A / B) exceeds 2.0, the opening property is lowered, and the weight of the nonwoven fabric and the strength are likely to be reduced. On the other hand, when the polymer component arc length ratio (A / B) is less than 0.1, the external stress is not sufficiently applied to the joining interface of the two components at the time of the division treatment, and the separation division becomes difficult.

  The arc length of each polymer component can be arbitrarily set by changing the method of joining the polymer components in the composite spinneret, the weight ratio, or the viscosity ratio at the confluence portion in the die. In particular, the melt viscosity of each polymer is changed by setting the melt temperature immediately before the melt-extruded polymer flows into the spin block (hereinafter referred to as “conduit polymer temperature”). A method of setting the arc length ratio (A / B) is simple and preferable.

  In this way, the split split-type composite continuous fibers arranged radially can be arbitrarily set by dividing the two components by a method in which the two components are melted and then merged in the die, and the single yarn fineness of the composite long fibers before splitting Is determined in consideration of Of these, 4 to 48 divisions, particularly 8 to 24 divisions, are particularly preferable from the viewpoints of yarn-making properties, ease of division, and effects thereof.

  In addition, the composite ratio with respect to the whole of one component of the above-described peelable split composite long fiber is in the range of 30 to 70% by weight from the viewpoint of the spinnability of the composite long fiber and the formation of split ultrafine fibers after making the long fiber nonwoven fabric described later. In particular, the range of 40 to 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 peelable composite long fiber as a whole is arbitrary, such as a round cross-sectional shape, a multi-leaf cross-sectional shape, and a polygonal shape, and may have a hollow part. This is preferable because the interfacial length can be reduced, and the separation of separation can be improved.

  The range of 0.01 to 0.60 dtex is appropriate for the single yarn fineness after the separation treatment. More preferably, it is 0.05-0.3 dtex. Those having a value of less than 0.01 dtex are difficult to produce, while those having a value of more than 0.60 dtex are liable to have large spots due to a decrease in the cover factor of the resulting nonwoven fabric, and the texture tends to decrease.

  The thermoplastic elastomer used in the present invention is not particularly limited as long as it is thermoplastic, and any of polyurethane-based elastomers, polyester-based elastomers, polyolefin-based elastomers and the like can be used. Of these, polyester elastomers are particularly preferable from the viewpoints of fiber splitting properties during splitting and thermal stability during fiber formation.

The polyester-based elastomer is a block copolymer composed of a hard segment made of polyester having crystallinity and a soft soft segment made of polyether and / or polyester.
As the polyester having crystallinity constituting the hard segment, 50 mol% or more, particularly 70 mol% or more of the acid component is a terephthalic acid form, and 50 mol% or more, particularly 70 mol% or more of the diol component is 1, A polybutylene terephthalate-based polyester that is 4-butanediol is preferred. Examples of other dicarboxylic acids that can be copolymerized include isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, adipic acid, and the like. Examples of the diol include ethylene glycol, trimethylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, and the like.

  Moreover, as a polyether which comprises the said soft segment, polyethyleneglycol, polybutylene glycol, polypropylene glycol, these copolymerization polyethers, etc. are suitable, and you may use individually or in combination of multiple. The average molecular weight is suitably in the range of 500 to 5,000 from the viewpoint of the elastic performance of the fiber and the heat resistance during molding.

  Examples of the polyester constituting the soft segment include aliphatic polyesters composed of hydroxycarboxylic acids such as polycaprolactone, aliphatic dicarboxylic acids having 4 to 20 carbon atoms and / or aromatic dicarboxylic acids having 8 to 16 carbon atoms. As a component, an aliphatic diol having 3 to 20 carbon atoms is used as a diol component, and a polyester having a glass transition temperature of room temperature or lower is suitable, and other components are copolymerized within a range that does not impair the performance as an elastomer. You may do it.

  If the weight ratio of the soft segment in the elastomer is too small, the elastic performance is lowered, and if it is too large, the heat resistance, molding processability, openability, etc. are lowered and the texture and quality of the nonwoven fabric are deteriorated. Therefore, the range of 30 to 90% by weight, particularly 40 to 80% by weight, more preferably 50 to 70% by weight is appropriate.

  In the present invention, it is important to blend 5 to 30% by weight, preferably 8 to 25% by weight of polybutylene terephthalate-based polyester with the above thermoplastic elastomer. By doing so, even when spinning at a high perforation density as in the spunbond method, for example, the sticking of the fibers can be suppressed, and the fiber opening property is remarkably improved. As a result, the uniformity at the time of collecting the fibers as a nonwoven fabric is improved, and a nonwoven fabric having excellent uniformity can be obtained even when a splitting process described later is performed. The polybutylene terephthalate-based polyester may be copolymerized with a small amount of the third component, but it is necessary that the crystallinity is not significantly impaired. When the content of the polybutylene terephthalate polyester is less than 5% by weight, the anti-sticking effect is insufficient, and when it exceeds 30% by weight, the process stability of the spunbond decreases, which is not preferable.

  The method for incorporating the polybutylene terephthalate-based polyester into the thermoplastic elastomer is not particularly limited, and is a method of adding the thermoplastic elastomer to be produced, melting after mixing the respective polymers when melt spinning the composite long fiber. Arbitrary methods such as a kneading method and a kneading method before spinning separately melted polymers can be adopted. In particular, from the viewpoint of the heat resistance of each polymer and the workability of melt spinning, it is desirable to mix each polymer chip and then melt-knead and use it for spinning.

  On the other hand, examples of the polyamide-based polymer include nylon-6, nylon-66, nylon-610, nylon-11, nylon-12 and the like. Among these, nylon-6 is preferable in terms of process stability and cost. preferable.

  As long as the object of the present invention is not impaired, additives such as carbon black, titanium oxide, aluminum oxide, silicon oxide, calcium carbonate, mica, fine metal powder, organic pigment, inorganic pigment, thermoplastic elastomer And may be added to any of the polyamide-based polymers. These additives are effective not only for coloring effects but also for adjusting the fiber cross-sectional shape because they have the effect of increasing or decreasing the melt viscosity.

  In the present invention, the above-described exfoliated split type composite continuous fiber is formed into a web on the porous collecting surface while opening the drawn yarn once wound by the spunbond method or by spinning and 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 traction is suitably in the range of 2,000 to 8,000 m / min, particularly in the range of 3,000 to 6,000 m / min, and the composite long fiber discharged from the spinneret is ejected. Or towing at high speed in the above range by air soccer or the like. 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 fiber 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 possible to mix other short fibers or to laminate and mix other long fibers. Other fiber materials to be mixed or laminated and mixed are not particularly limited. For example, recycled fibers such as rayon, semi-synthetic fibers such as acetate, natural fibers such as wool, nylon-6, nylon-66, etc. One type or two or more types can be arbitrarily selected from polyamide fibers, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, and polyolefin fibers such as polyethylene and polypropylene. Of course, the fiber shape and the like are not limited, and any one of a core-sheath type composite fiber, a peelable split type composite fiber combining two or more types of thermoplastic resins, and other fibers having an irregular cross section can be used. .
The long fiber web obtained in this manner is formed by laminating a plurality of sheets as needed, or independently, preliminarily thermally bonded as necessary, and once wound up or continuously. A long fiber nonwoven fabric is obtained by performing an entanglement process such as a punch process.

  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, as a mechanical division treatment method, a method of pressurizing between rollers, a method of ultrasonic treatment, a method of applying an impact, a method of stagnation treatment can be exemplified, and the chemical method is one of the constituents. Examples of the method include a treatment in a solvent in which only the polymer is swollen or reduced in weight. When aiming at densification of a nonwoven fabric or the like, it is preferable to perform shrinkage heat treatment subsequent to the division treatment, so it is preferable to avoid a division treatment method in which heat is applied before fiber division is performed.

  The ultra-thin fiber nonwoven fabric obtained by the production method of the present invention described above is used for base materials for artificial leather, for clothing, for industrial materials such as interior materials and interior materials, and for wipers such as industrial wipers and wiping cloths. It can be preferably used for filter applications such as bag filters and filter cloths, and medical hygiene materials.

Hereinafter, the present invention will be described more specifically with reference to examples.
In the examples, “part” and “%” are based on weight unless otherwise specified, and each measured value is determined according to the following method. Unless otherwise specified, the measured value is an average of 5 points. Value.

<Nonwoven fabric weight spot (CV%)>
The nonwoven fabric was cut into small pieces having a width of 2 cm and a length of 20 cm so that the width was in the width direction of the nonwoven fabric, and the weight was measured. .

<Opening property>
The web before separation was sampled and the open state was visually determined.
Level 1: The fibers are evenly spread and almost no string-like entanglement is seen. There is almost no appreciation of the basis weight.
Level 2: Although some string-like fibers in which several fibers are entangled with each other in the longitudinal direction of the fibers are seen, the openability is relatively good and the local basis weight is low.
Level 3: Numerous cord-like fibers in which several fibers are entangled with each other in the longitudinal direction of the fiber or those in which cord-like fibers are further entangled are observed. There is also a local basis height.

<Division ratio>
The split ratio of the peelable split composite long fibers is obtained by photographing the 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 (not completely split, for example, The difference was obtained by dividing the difference in cross-sectional area of the filaments (including those divided into two or three pieces) by the total area. The larger the division ratio, the better the division

<Fineness of extra fine fibers>
The fineness of the undivided fibers is measured by a fineness measuring device (SERCH CO. LTD, model DC-21) with a test length of 2.5 cm and a load of 1 g, and is obtained by dividing the number by the number of divisions constituting the fiber cross section. It was.

<Tensile strength>
In accordance with the method described in JIS L-1096, a sample piece having a width of 5 cm and a length of 15 cm is gripped at a spacing of 10 cm, and stretched at a tensile speed of 30 cm / min using a constant speed stretch type tensile tester, and stretched by 20%. The stress at the time was the tensile stress (σ20), and the load value at the time of cutting was the tensile strength. The tensile strength was determined by converting per width of 1 cm and sample weight per 100 g / m ² .
<Spinnability>
The yarn was spun continuously for 3 days, the yarn breakage and the polymer discharge state were observed at that time, and the state where defects such as polymer drip appeared on the web was regarded as defective.

Example 1
After transesterification of 167 parts of dimethyl terephthalate, 105 parts of tetramethylene glycol and 325 parts of polytetramethylene glycol having a number average molecular weight of 2,000 in the reactor, the internal temperature was raised to 245 ° C. The reaction was performed for 60 minutes, followed by reaction for 200 minutes under high vacuum. The resulting polyether polyester block copolymer (thermoplastic elastomer) had a melting point of 190 ° C. and an intrinsic viscosity (measured in o-chlorophenol at 35 ° C., the same applies hereinafter) of 1.52 dL / g. This chip was dried at 115 ° C. for 16 hours under reduced pressure of 133 Pa, and then 10% chip blended with polybutylene terephthalate (in o-chlorophenol, intrinsic viscosity at 35 ° C .: 0.88 dL / g, the same applies hereinafter). On the other hand, as a polyamide polymer, nylon-6 dried at 120 ° C. (in m-cresol, intrinsic viscosity at 30 ° C .: 1.1 dL / g) was melted separately with an extruder, and then in the die And discharged from a round hole with a solid round cross-section at a discharge rate of 1 g / min from a die perforated with 4,000 holes per 1 m width at an air soccer pressure of 343 kPa (3.5 kg / cm ² ). After pulling at a high speed, a high voltage is applied at −30 kV, colliding with a dispersion plate together with an air flow, the filament is opened, and a split split type composite long fiber having a 16 split multi-layer laminating section shown in FIG. A web made of (weight ratio of both components 50/50, single yarn fineness 4.1 decitex) 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 was lightly heat-bonded continuously with an embossed calender at 100 ° C. up and down, and the composite long fiber was divided into ultrafine fibers and entangled with a high-pressure columnar water flow at a pressure of 15 MPa. The obtained nonwoven fabric had a basis weight of 45 g / m ² and was a nonwoven fabric having good uniformity, softness and excellent texture. Table 1 shows the physical properties of the obtained nonwoven fabric.

Example 2
194 parts of dimethyl terephthalate, 162 parts of tetramethylene glycol, and 0.15 part of titanium tetrabutoxide are charged into a transesterification reaction kettle, heated to 190 ° C. in a nitrogen gas atmosphere, and the produced methanol is allowed to flow out of the system. The transesterification reaction was carried out. After the transesterification reaction, polycondensation reaction was performed at 230 ° C. under reduced pressure to obtain polybutylene terephthalate having an intrinsic viscosity of 1.07 dL / g and a melting point of 223 ° C.
On the other hand, 136 parts of dimethyl isophthalate, 62 parts of dimethyl sebacate and 180 parts of 1,6-hexanediol were heated together with 0.3 part of dibutyltin acetate to remove by-product methanol from the reaction system. The reactive organism was transferred to a reaction vessel capable of reducing pressure and reacted at 255 ° C. under reduced pressure to obtain an amorphous polyester having an intrinsic viscosity (measured in o-chlorophenol at 35 ° C.) of 0.80 dL / g.
The polybutylene terephthalate and the amorphous polyester were added so as to have a weight ratio of 35:65, reacted at an internal temperature of 240 ° C. for 50 minutes under a reduced pressure of 133 Pa, and then phenylphosphone as a catalyst deactivator. 0.2 parts of acid was added and the mixture was further stirred for 10 minutes to obtain a polyester polyester block copolymer (thermoplastic elastomer). This polymer had an intrinsic viscosity of 1.15 dL / g and a melting point of 205 ° C.
A long fiber nonwoven fabric was obtained in the same manner as in Example 1 except that this polymer was used as a thermoplastic elastomer. The physical properties of this product are shown in Table 1.

Examples 3-5, Comparative Examples 1-3
A long fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the amount of polybutylene terephthalate mixed in the thermoplastic elastomer in Example 1 was changed as shown in Table 1. These physical properties are also shown in Table 1.

PBT: Polybutylene terephthalate MD / CD: Nonwoven fabric longitudinal (machine) direction / lateral direction

  As is clear from Table 1, in Examples 1, 2, and 3 to 5, long fiber nonwoven fabrics that are excellent in uniformity and that have been divided into ultrafine fibers and excellent in texture are obtained. On the other hand, in Comparative Example 1 and Comparative Example 2, only the nonwoven fabric inferior to the texture in which the fiber spreadability is low and the uniformity is low and the split ultrafine fibers are not sufficiently formed is obtained. Further, in Comparative Example 3, although the openability is good, the spinning stability is poor and the fiber is cut, so that only the non-uniformity of the fabric weight and the strength are reduced as a result. Absent.

  The ultra-thin fiber non-woven fabric produced by the production method of the present invention has no texture due to suppression of inter-fiber sticking, and has excellent texture because it contains ultra-fine fibers made of an elastomer. Therefore, taking advantage of such characteristics, it can be suitably used for applications such as artificial leather base fabrics, wipers, filters and medical hygiene materials, and its industrial value is extremely high.

It is one schematic diagram of the cross section of the peeling division | segmentation type | mold composite continuous fiber concerning this invention. It is one schematic diagram of the cross section of the peeling division | segmentation type | mold composite continuous fiber concerning this invention.

Explanation of symbols

1 Thermoplastic Elastomer Polymer 2 Polyamide Polymer

Claims (3)

  Separation treatment is applied to a long-fiber nonwoven fabric composed of release-divided composite long fibers composed of a thermoplastic elastomer containing 5 to 30% by weight of a polybutylene terephthalate-based polyester and a polyamide-based polymer. A method for producing an ultra-fine long-fiber non-woven fabric, characterized in that the fiber is made into ultra-fine fibers.   The method for producing an ultra-thin fiber nonwoven fabric according to claim 1, wherein the thermoplastic elastomer is a polyether ester elastomer. The method for producing an ultra-thin fiber nonwoven fabric according to claim 1 or 2, wherein the single yarn fineness after ultra-thinning is 0.01 to 0.6 dtex.