JPWO2005042824A1 - Ultrafine fiber nonwoven fabric and method for producing the same - Google Patents

Abstract

A method for producing a split-type composite spun fiber nonwoven fabric that is excellent in flexibility, wiping property, and dust collection property and that can be produced at low cost, and an ultrafine fiber nonwoven fabric obtained thereby. Dissolved two types of resins are ejected from a spinneret having a composite spinning nozzle and stretched to deposit split composite fiber-type long fibers having a predetermined fineness by drawing on a collection belt to form a nonwoven fabric, Furthermore, it is an ultrafine fiber nonwoven fabric having a fineness of 0.01 to 2.0 d (denier) obtained by applying an extension force, and the ultrafine fiber nonwoven fabric is produced so that the fineness of the constituent fibers is uniform, thereby obtaining the target nonwoven fabric.

Description

  The present invention relates to an ultrafine fiber nonwoven fabric made of two types of incompatible resins. More specifically, a split type composite fiber nonwoven fabric excellent in wiping property, water retention or water repellency, excellent in flexibility, and can be produced at low cost, and a wiper, an absorbent article, a sanitary material using the same, and a method for producing the same About.

  Nonwoven fabrics are used in a variety of ways, including clothing, disposable diapers, personal hygiene products, and industrial materials. In order to obtain required performance such as excellent flexibility, tactile sensation, and wiping property in use in these fields, ultrafine fiber nonwoven fabrics have been conventionally applied.

  As one method for obtaining an ultra-fine fiber nonwoven fabric, a split-type composite fiber is manufactured using two types of mutually incompatible resins, and a physical force is applied to the composite fiber so-called split fiber. Is known as a known technique for obtaining ultrafine fiber non-woven fabrics by obtaining the ultrafine fibers and obtaining the ultrafine fibers, then splitting them at the same time by hydroentanglement treatment or needle punching treatment (Patent Document 1). , Patent Document 2 and Patent Document 3). However, these methods cannot give an impact by a needle or a high-pressure water stream to all parts of the split type composite fiber, and only those having a low degree of splitting can be obtained. That is, there is a drawback in that a relatively large number of split-type composite fibers that are not partially split remain in the nonwoven fabric and the amount of ultrafine fibers is small, so that flexibility is lacking. Furthermore, there has been a drawback that the split type composite fibers are entangled three-dimensionally with each other due to the impact of the needle or high-pressure water flow, and the resulting nonwoven fabric is densified and lacks flexibility.

As another method, a method of obtaining an ultrafine fiber nonwoven fabric by so-called stretching treatment is also known. For example, the stretching process described in Patent Document 4 introduces a nonwoven fabric sheet between a supply roll that rotates at a constant circumferential speed and a stretching roll that rotates at a higher peripheral speed than the supply roll, and the supply roll And a non-woven sheet between the stretching rolls. This method is preferable in that the production process is simple. According to the specification, when an elongation treatment satisfying 1 + 0.001E <ST <1 + 0.01E (E: maximum elongation (%) of nonwoven fabric sheet, ST: elongation ratio of nonwoven fabric sheet) is applied, it results from three-dimensional entanglement. It is described that a non-woven fabric rich in flexibility can be obtained with little risk of lowering flexibility. However, under the above conditions, the force due to stretching applied to the nonwoven fabric becomes non-uniform, and in some cases, only a nonwoven fabric in which split-type composite fibers are partially split can be obtained. In another case, the nonwoven fabric sheet may be partially or totally broken.
When obtaining a split-type ultrafine fiber nonwoven fabric, it is known that it is preferable to use a composite fiber composed of two types of incompatible resins because a split fiber can be easily obtained. In that case, the resulting product is a mixture of those resins. For example, when a split type composite fiber of a polyolefin resin having a lipophilicity on the fiber surface and a polyester resin having a relatively hydrophilic property is obtained, the fiber is hydrophilic. Since it has lipophilicity, it is expected to be preferable because wiping property is improved.

In this regard, in JP 2004-100084 (Patent Document 5), a hydrophilizing agent is kneaded into at least one of the split-type conjugate fibers, and at the same time, a hydrophilicity-imparting oil is adhered to the outer peripheral surface thereof. A hydrophilic nonwoven fabric is described in which the nonwoven fabric is molded under conditions that do not receive an elongation force that does not cause division between constituent fibers. In the present invention, the hydrophilicity is maintained by performing the hydrophilizing agent and the hydrophilicity imparting agent on at least one kind of resin constituting the split-type conjugate fiber. Since it is not a fiber nonwoven fabric, the expected effect cannot be obtained in terms of water retention.
JP 58-169557 A JP 60-71752 A JP-A-60-71753 JP-A-9-310259 JP 2004-100084 A

  The object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to produce an ultrafine fiber nonwoven fabric that is excellent in flexibility, wiping property and dust collection property and can be produced at low cost, and the ultrafine fiber nonwoven fabric obtained thereby. As well as wipers and hygiene materials using the same.

  As a result of diligent investigations to solve the above problems, the present inventors have discharged a plurality of molten incompatible resins from a spinneret having a composite spinning nozzle for split-type composite fibers, and drawing them simultaneously with cooling by air. The spun long fibers spun on the collection belt, collected after heat embossing, and bonded, and then applied with an extension force to provide excellent flexibility, wiping and dust collection. The present inventors have found that it is possible to obtain a non-woven fabric that can be produced at low cost.

  That is, the present invention relates to a nonwoven fabric in which two types of different resins are ejected from a spinneret having a composite spinning nozzle and stretched, and split composite fiber-type long fibers having a predetermined fineness are deposited on the collection belt. And an ultrafine fiber nonwoven fabric having a fineness of 0.01 to 2.0 d (denier) obtained by applying an extension force, and the fineness of the constituent fibers is uniform.

  Moreover, the fiber of the ultrafine fiber nonwoven fabric of the present invention is characterized in that the standard deviation of the number of segments forming the filament cross section of the ultrafine fiber is 6 or less.

  Moreover, it is one of the preferable embodiments of the present invention that the at least two different resins used in the present invention are a polyolefin polymer and a polyester polymer.

  Furthermore, it is one of the most preferred embodiments of the present invention that the polyolefin polymer used in the present invention is a polypropylene polymer, and the polyester polymer is a polylactic acid polymer.

  One of the preferred embodiments of the present invention is that the fibers of the composite fiber nonwoven fabric used in the present invention are composite fibers made of at least two different resins, and are produced by applying an extension force.

  The stretching force used in the present invention is applied by fixing the composite fiber nonwoven fabric used in the present invention at a point separated by a distance of 0.1 to 100 mm (millimeters) and uniformly stretching between the fixings. And

  This invention provides the nonwoven fabric which consists of a fiber with a fineness of 0.01-2.0d (denier) which consists of at least 2 types of different resin, and at least 1 resin contains a hydrophilic compound.

  When the ultrafine fiber nonwoven fabric of the present invention is manufactured, the elongation force according to the present invention is applied by gear stretching.

  The gear drawing process used in the present invention is a drawing ratio expressed by gear depth (H) mm and gear pitch (W) mm, and maximum elongation (E) obtained in a test according to the strip method described in L-1096. It is one of the preferable embodiments that the relationship with% satisfies the following mathematical formula.

  The present invention provides a wiper comprising the ultrafine fiber nonwoven fabric of the present invention.

  The present invention provides a sanitary material comprising the ultrafine fiber nonwoven fabric of the present invention.

  According to the method of the present invention, split-type composite fibers can be split highly and uniformly, so that an ultrafine fiber nonwoven fabric that is excellent in flexibility, wiping property, and dust collection property and can be produced at low cost is obtained. In addition, when only the water repellency, alcohol resistance, or hydrophilic property of the polyester fiber is desired, the properties expected of the respective fibers can be expressed by using the present invention. For example, a product having desired properties can be obtained by devising a combination of split-type fibers.

It is the schematic diagram which showed an example of the cross section of the split type composite fiber filament which concerns on this invention. It is the schematic which shows one embodiment of the uniform extending | stretching process for splitting the split type composite fiber which concerns on this invention. It is the schematic which shows the measurement part of the division | segmentation rate and standard deviation of the split type composite fiber nonwoven fabric which gave the gear extension obtained in the Example. It is the schematic which shows the measurement location of the division | segmentation rate and standard deviation of the split type composite fiber nonwoven fabric which gave the gear extension obtained by the comparative example. It is a figure of the electron micrograph of the ultrafine fiber nonwoven fabric of this invention obtained in the Example. It is a figure of the electron micrograph which shows the fiber cross section of the ultrafine fiber nonwoven fabric which concerns on this invention. It is a figure of the electron micrograph of the ultrafine fiber nonwoven fabric obtained by the comparative example.

  Hereinafter, the present invention will be described in detail.

(Explanation of terms)
As used herein, “fineness variation” is defined by standard deviation.

  The standard deviation was evaluated by the following equation for the variation in the number of segments of the section of the split composite fiber observed 30 times with an electron microscope. The larger the standard deviation is, the more non-uniformity is.

Sn: Standard deviation n: Number of tests (30 times)
Xi: Number of observed segments Xave: Average value of the number of observed segments for 30 tests The “split type composite fiber” as used in the present invention is intended to form a cross-sectional structure in a radial, parallel or parallel manner. A composite long fiber is said to be discharged from a spinneret having a composite spinning nozzle.

(resin)
The resin used as the material of the split-type composite fiber of the present invention is a combination of two or more different resins, and when split-type composite fiber is used, it is a resin that can be easily split by mechanical impact or the like. Means a combination.

  Specifically, thermoplastic resins and elastomers such as polyolefin polymers, polyester polymers, polyamide polymers, polyurethane polymers, and polycarbonates are used. Among these, a combination of resins selected from polyesters and polyolefins is preferable.

  Examples of polyolefin polymers include polyolefin resins such as polyethylene and polypropylene, copolymers with α-olefins such as polyolefin elastomers, polystyrene resins, and polystyrene elastomers.

  Examples of the polyester resin used in the present invention include polyethylene terephthalate, polyethylene terephthalate copolymer, polybutylene terephthalate, polybutylene terephthalate copolymer, polyglycolic acid, glycolic acid copolymer, polylactic acid, and lactic acid copolymer. Etc. can be illustrated.

  Polyamide resins used in the present invention include 6,6-nylon, 6,10-nylon, 6-nylon, 1,1-nylon, 1,2-nylon, 4-nylon, 4,6-nylon, and these Examples thereof include copolymers mainly composed of.

(fiber)
As a specific example of the split type composite fiber composed of two or more different types of resins, those having a cross section as shown in FIGS. 1 (a) to 1 (d) are preferable. In these, two types of resin parts are both exposed on the surface of the filament, and one resin part is partitioned in a form that can be split by the other resin part in the cross section of the filament. The example of the cross section of FIG. 1 is a typical example, and unless the object of the present invention departs, a split type composite fiber having a cross section other than the above is manufactured by appropriately selecting a spinneret. I can do it.

  When the split-type conjugate fiber of the present invention is made of two types of incompatible resins, the ratio of the resin part A and the resin part B is preferably equal, but is not limited to this, and A to B ( The weight ratio is preferably 90 to 10 to 10 to 90, and more preferably 70 to 30 to 30 to 70.

  The resin used for the split-type composite fiber in the present invention is appropriately selected for the application. In particular, when used for paper diapers, wipers, etc., it is necessary to suppress the occurrence of fuzz. For this purpose, at least a part of the fiber surface is a polymer of the resin part formed continuously in the length direction. The polyolefin polymer used is preferably a polypropylene polymer. Also, in the case of split type composite fibers made of two different types of resins, the split type composite fiber spinning die used for its production has two flow paths, so when the melting point difference between the two types of resins is large, The temperature distribution in the die becomes uneven, and there is a concern about the thermal decomposition of the low melting point resin. Furthermore, there is a concern about fusion between filaments due to a crystallization delay in the cooling process, which may make molding difficult. The melting point difference between the two resins is usually 0 to 200 ° C, preferably 0 to 100 ° C, and most preferably 0 to 50 ° C. Therefore, when a polypropylene polymer is used for one resin, the other resin is preferably a polylactic acid polymer having a melting point close to that of the polypropylene polymer.

(Polypropylene polymer)
The polypropylene polymer preferably used in the present invention is a propylene homopolymer or a copolymer containing propylene as a main component and at least one other α-olefin. Examples of other α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and the like. Mention may be made of olefins. These homopolymers or copolymers can be used singly or in combination of two or more.

  The MFR of the polypropylene polymer is usually 1 to 1000 g / 10 minutes, preferably 5 to 200 g / 10 minutes, more preferably 10 to 120 g / 10 minutes. Here, the MFR of the polypropylene-based polymer is measured at 230 ° C. under a load of 2.16 kg based on ASTM D1238. The ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polypropylene-based polymer is usually 1.5 to 5.0, and the spinnability is good and the fiber strength is particularly high. 1.5-3.0 are preferable at the point from which the outstanding composite fiber is obtained. In the present invention, good spinnability means that yarn breakage does not occur during discharge from the spinning nozzle and during drawing, and filament fusion does not occur. In the present invention, Mw and Mn can be measured by a known method by GPC (gel permeation chromatography).

(Polylactic acid polymer)
The polylactic acid polymer preferably used in the present invention includes poly (D-lactic acid), poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, and a copolymer of D-lactic acid and hydroxycarboxylic acid. Examples thereof include any one selected from a polymer, a copolymer of L-lactic acid and a hydroxycarboxylic acid, or a blend thereof. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, and the like. In addition, a crystal nucleating agent may be added to the polylactic acid-based polymer as necessary within a range not impairing the effects of the present invention. Examples of the crystal nucleating agent include biodegradable polymers having a nucleating agent effect such as polybutylene succinate, talc, boron nitride, calcium carbonate, titanium oxide and the like.
The melting point of the polylactic acid polymer is preferably 100 ° C. or higher, more preferably 150 ° C. to 180 ° C. In addition, it is preferable that the polylactic acid polymer has a weight average molecular weight (Mw) of 100,000 to 200,000 g / mol in that a composite fiber having good spinnability can be obtained.

(Hydrophilic agent)
In the split composite fiber of the present invention, as a component to be contained in at least one resin part, when the resin forming the resin part is a water-repellent resin, for example, fatty acid glyceride, alkoxylated alkylphenol, polyoxyalkylene fatty acid ester, Nonionic surfactants such as alkyl polyoxyethylene alcohols and fatty acid amides, fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, special anions and other group of surfactants , Polyethylene glycol, a copolymer of vinyl alcohol and ethylene polymer, and a polyether block amide copolymer, which are appropriately selected from a group of compounds, can be used alone or as a mixture.

For example, in the case of a split type composite fiber composed of two types of incompatible resins, a polyester resin and a polyolefin resin, examples of preferable components added for the purpose of imparting hydrophilicity to the polyolefin resin include:
General _{formula: R- (CH 2 CH 2 O} ) n -OH
(In the formula, R is a linear or branched alkyl group having 22 to 40 carbon atoms, and n is an integer of 2 to 10).
Is mentioned.
The amount to be added is preferably 0.5 to 10% by weight, more preferably 2 to 7% by weight in one resin part.

(Additive)
The incompatible resin used in the present invention can be blended with additives that impart other functionalities within the scope of achieving the object of the present invention. be able to. Examples of additives include conventionally known heat stabilizers, weather stabilizers, various stabilizers, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants, dyes, pigments, natural oils, synthetic oils, and waxes. Etc.

  Examples of the stabilizer include anti-aging agents such as 2,6-di-t-butyl-4-methylphenol (BHT); tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxy Phenyl) propionate] methane, β- (3,5-di-t-butyl-4-hydroxyphenyl) propionic acid alkyl ester, 2,2′-oxamide bis [ethyl-3- (3,5-di-t-butyl) -4-hydroxyphenyl)] propionate, Irganox 1010 (hindered phenolic antioxidant: trade name) and other phenolic antioxidants; fatty acid metal salts such as zinc stearate, calcium stearate, calcium 1,2-hydroxystearate Glycerin monostearate, glycerin distearate, pentaerythritol monostearate And polyhydric alcohol fatty acid esters such as pentaerythritol distearate and pentaerythritol tristearate. Moreover, these can also be used in combination.

  Also, silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloon, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, calcium sulfite, A filler such as talc, clay, mica, asbestos, calcium silicate, montmorillonite, bentonite, graphite, aluminum powder, molybdenum sulfide may be included.

  The polypropylene-based polymer and polylactic acid-based polymer can be mixed with other optional components used as necessary using a known method.

(Production method)
As a production method for obtaining an ultrafine fiber nonwoven fabric composed of a plurality of different resins according to the present invention, the spunbond method is preferred in terms of good productivity and high strength.

  A spunbond method will be described as an example as a method for producing the ultrafine fiber nonwoven fabric of the present invention. As illustrated in FIGS. 1 (a) to 1 (d), the melts of the two types of incompatible resins constituting the split-type conjugate fiber are formed in a radial, parallel or parallel cross-sectional structure. The long fibers having a predetermined fineness by being discharged from a spinneret having a composite spinning nozzle and drawn are collected on a moving collection belt as it is and deposited to a predetermined thickness. Next, heat embossing is performed by heat fusion with a heat embossing roll. In the case of heat fusion with a hot embossing roll, the embossing area ratio of the embossing roll is appropriately determined, but is usually preferably 5 to 30%.

The fineness after spinning of the split-type composite fiber is usually preferably 6 denier or less. If it is 6 deniers or less, for example, the fineness after splitting treatment by stretching or the like can be reduced, and wiping properties and flexibility are excellent, which is preferable. Moreover, 3-200 g / m < ² > is preferable and, as for the fabric weight of the split type composite fiber nonwoven fabric of this invention, 10-150 g / m < ² > is more preferable.

Furthermore, the obtained split type composite fiber nonwoven fabric can be split by applying an extension force. The stretching force is applied so that the composite fiber nonwoven fabric is fixed at two points separated by a certain distance and processed to be uniformly stretched in the fixed feeling. By applying an extension force in this way, the composite fiber nonwoven fabric is split more highly and uniformly. The distance between fixations is usually 0.1 to 100 mm, preferably (0.1) to (50) mm, and more preferably (0.1) to (10) mm. Whether or not the film can be stretched uniformly depends on the distance between the fixings. If the distance between the fixings is too short, the stretching may be insufficient. If it is too far, the variation in the basis weight contained in the nonwoven fabric can be ignored. In some cases, uniformity due to location may be a problem. By uniformly stretching, it is possible to reduce the standard deviation value indicating the variation in the splitting property of the split-type composite fiber nonwoven fabric after processing. The standard deviation is preferably 6 or less, and more preferably 5 or less.
One of the features of the stretching force used in the present invention is that the stretching is performed by uniformly applying the stretching force to the whole nonwoven fabric. Various stretching methods can be used as a method for uniformly stretching the entire nonwoven fabric without departing from the object of the present invention. For example, a gear stretching process using a gear stretching apparatus as shown in FIG. Can give. Moreover, the extending | stretching process which passes between the roll which has many convex-shaped protrusions, and the roll which has many dents of the magnitude | size which the protrusions can accommodate can be mention | raise | lifted.
In the present invention, it is desirable that the splitting rate of the split-type composite fiber after splitting is 30% or more. In particular, it is preferably 60% or more from the viewpoint of flexibility, wiping properties, and dust collection. The split state and split ratio of the split-type composite fiber can be adjusted by changing the line speed, gear depth, gear pitch and other conditions when passing through the gear stretcher.

(Extra-fine fiber nonwoven fabric)
The fineness of the ultrafine fiber nonwoven fabric produced by the method of the present invention is usually 0.01 to 2.0 d (denier), preferably 0.01 to 1.2 d (denier).

Gear stretching conditions for obtaining sufficient flexibility, wiping performance, and dust collection performance are based on the stretching ratio represented by gear depth (H) mm and gear pitch (W) mm and the strip method described in L-1096. In the test, it is preferable that the relationship with the maximum elongation (E)% satisfies the following mathematical formula, and the stretching conditions change depending on the relationship with the desired strength and lint-free property.

  Moreover, the split fiber expressed by the drawing process in the present invention is not substantially three-dimensionally entangled with each other. This is because an elongation force is simply applied to the composite continuous single yarn, and no force is applied to move the composite continuous single yarn in a random direction.

For example, there is a method in which a high-pressure liquid flow is applied to a non-woven sheet, and the composite continuous single yarn is impacted and split into pieces. In this method, the composite continuous single yarn moves in a random direction by the high-pressure liquid flow. However, the composite continuous single yarn and split fiber are substantially three-dimensionally entangled with each other.
Therefore, in the nonwoven fabric obtained by the method according to the present invention, the split fibers are not substantially three-dimensionally entangled, so that the decrease in flexibility of the nonwoven fabric due to the entanglement can be prevented. In addition, substantially three-dimensional entanglement here refers to close entanglement that occurs when processing with a needle punch or high-pressure columnar flow, and entanglement due to fiber bending or the like is substantially entangled. Not say.

  In the present invention, a hydrophilic compound can be contained in one of two different resins. The divided fiber containing the hydrophilic compound has a fineness of usually 0.01 to 2.0 denier, preferably 0.01 to 1.2 denier. At such fineness, water retention and flexibility are improved.

  The ultrafine fiber nonwoven fabric of the present invention can have various properties due to the difference in the combination of the two types of resins during spinning of the composite fiber. For example, an ultrafine fiber nonwoven fabric obtained by a combination of polyolefin and polyester has flexibility and good wiping performance for both water and oil. Further, even if the same polyolefin and polyester are combined, if a hydrophilic agent is added to polyolefin having higher hydrophobicity than polyester, an ultrafine fiber nonwoven fabric having water retention in addition to flexibility can be obtained. Furthermore, in the case of an ultrafine fiber nonwoven fabric using different types of polyolefins, it has water repellency in addition to flexibility.

  The ultrafine fiber nonwoven fabric of the present invention may be a mixed nonwoven fabric with other fibers depending on the application.

  Moreover, the obtained split type composite fiber nonwoven fabric can be laminated on other nonwoven fabrics, films, etc. according to the desired performance, and it can be set as the nonwoven fabric laminated body which has at least 1 layer of a split type composite fiber nonwoven fabric. As a result, it can be applied to more applications.

  EXAMPLES Hereinafter, although an Example shows this invention, this invention is not limited by these Examples. In addition, the measurement and evaluation regarding the division ratio and standard deviation, texture, oil retention, fineness, wiping property, tensile strength, and lint-free property of the nonwoven fabrics obtained in Examples and Comparative Examples were performed by the following methods.

(1) Splitting rate and standard deviation The obtained split composite fiber nonwoven fabric is embedded in an epoxy resin, and then cut with a microtome to obtain a sample piece. This was observed with an electron microscope, and the division ratio was calculated by the following equation from the obtained cross-sectional image. This was observed for 30 fibers, and the average value was taken as the splitting rate of the split-type composite fiber nonwoven fabric.

Splitting rate [%] = {(total number of segments−number of observed segments of divided fiber cross section) / total number of segments} × 100
Here, the total number of segments refers to the total number of segments forming the filament cross section of the split composite fiber. For example, in the case of a split type composite fiber having a filament cross section as shown in FIGS. 1 (a) to 1 (d), the total number of segments is eight.

  Moreover, in order to evaluate a division rate and its uniformity, the division rate was measured at three locations of the divided nonwoven fabric obtained in each experiment. About the split-type composite fiber nonwoven fabric which carried out the gear extending | stretching process, it measured about three places (A, B, C in a figure) shown in FIG. The split type composite fiber nonwoven fabric subjected to split tension drawing was measured at three locations (A, B, and C) at the same interval in FIG. 6 in the drawing direction so as to correspond to those subjected to gear drawing.

  The standard deviation was evaluated by the following equation for the variation in the number of segments of the section of the split composite fiber observed 30 times with an electron microscope. The larger the standard deviation is, the more non-uniformity is.

Sn: Standard deviation n: Number of tests (30 times)
Xi: number of observed segments Xave: average value of the number of observed segments for 30 test times (2) Texture 10 touches were evaluated for touch. The evaluation results are shown according to the following criteria.

◎: When 10 people out of 10 feel that the touch is good,
○: If there are 9 to 7 people out of 10
Δ: When 6 to 3 out of 10 people feel that the touch is good,
X: When the number of people who feel that the touch is good is 2 or less out of 10 people.

(3) Oil retention rate The obtained split type composite fiber nonwoven fabric is cut into a size of 50 mm × 200 mm to obtain a test piece. Weigh the specimen weight _{W 0,} the oil (manufactured Yellow Hat Ltd., MAGMAX SL 5W-40 (AAA )) 3 seconds immersed into. Then, after removing by dropwise oil deposits and held in a 30 seconds air, weighed specimen weight W _1, to calculate the oil-retaining rate from the following formula. This was repeated 3 times and the average value was evaluated.

Oil retention [%] = {(W ₁ −W ₀ ) / W ₀ } × 100
(4) Fineness The split type composite fiber nonwoven fabric obtained is embedded in an epoxy resin and then cut with a microtome to obtain a sample piece. Next, it is observed with an electron microscope, 10 undivided filaments are selected from the obtained cross-sectional image, the cross-sectional area is calculated, the fineness of the undivided filaments is obtained from the average value thereof, and the following formula is used using the division ratio: Thus, the fineness of the split-type composite fiber was calculated.

Fineness of split-type composite fiber = fineness of unsplit filament / (total number of segments x split ratio / 100)
(5) Wiping property (wiping rate)
In a smooth metal pallet, 0.5 g of oil (manufactured by Yellow Hat, MAGMAX SL 5W-40 (AAA)) and 1.0 g of distilled water are hung and lightly wiped with a test piece cut to a size of 100 mm × 50 mm. The total remaining amount w of the oil and water in the metal pallet was measured, and the wiping property was calculated from the following formula, and this was repeated three times and evaluated with an average value. It shows that it is excellent in wiping property, so that the numerical value of wiping property is large.

Wiping rate [%] = {(1.5−w) /1.5} × 100
(6) Tensile strength In accordance with JIS L1906L, three non-woven fabric test pieces of 25 cm in the flow direction (MD) and 2.5 cm in the transverse direction (CD) were collected, and the conditions were 200 mm between chucks and 200 mm / min tensile speed. A tensile test was conducted on the three test pieces, and the tensile load was measured for the three test pieces, and the average value thereof was taken as the tensile strength.

(7) Lint-free property (dropout amount)
A commercially available double-sided tape (Nichiban NWBB15, manufactured by Nichiban Co., Ltd.) is cut into 15 mm × 200 mm, and the tape weight W [g] is measured. And this tape is affixed on a nonwoven fabric, The weight of 1.25 kg and a size of 300 mm x 95 mm is put on it. After holding for 60 seconds, the tape was peeled off, the tape weight W ′ [g] was measured, the dropout amount was calculated from the following formula, and this was repeated three times and evaluated with an average value. It shows that lint-free property is lacking, so that drop-off amount is large.

Dropout amount [g] = W′−W
Example 1
As two types of incompatible resins, polylactic acid (Mitsui Chemicals, trade name LACEEA, melting point 165 ° C.) having a weight average molecular weight Mw = 133400 is used as the first resin, and MFR = as the second resin. A split type composite fiber having a cross-sectional shape as shown in FIG. 1 (a) in which polypropylene (Mw / Mn = 2.7) of 60 g / 10 min is used and melted separately by an extruder, and the total number of segments is 16. Using a spinneret, split-type composite fibers having a weight ratio of the first resin to the second resin of 50/50 are deposited on a collection belt, and then heated and pressurized with an embossing roll ( Embossed area ratio 18%, embossing temperature 100 ° C), basis weight 40 g / m ² , constituent fiber fineness (undivided filament fineness) 0.88d, maximum elongation in a test according to the strip method described in L-1096 Degree 70 The splittable conjugate fiber nonwoven fabric was produced.

  Next, the obtained non-woven fabric was passed through a gear drawing machine (gear pitch 5 mm, non-woven web fixing point distance 2.5 mm) shown in FIG. 2 and drawn at a transverse draw ratio of 56% to obtain an ultrafine fiber non-woven fabric having a fineness of 0.34d. Produced. About the obtained nonwoven fabric, the division ratio, its standard deviation, texture, tensile strength, lint-free property, wiping rate, and oil retention rate were measured and evaluated. The evaluation results are shown in Table 1.

(Example 2)
The nonwoven fabric obtained in Example 1 was passed through a gear stretching machine having a gear pitch of 2.5 mm and stretched at a transverse stretching ratio of 160% (gear depth: 3.0 mm) to produce an ultrafine fiber nonwoven fabric having a fineness of 0.25d. . Table 1 shows the evaluation results of the obtained nonwoven fabric.

(Comparative Example 1)
A split type composite fiber nonwoven fabric was produced in the same manner as in Example 1. Using a tensile tester, the obtained nonwoven fabric was stretched at a stretch ratio of 56% in the flow direction (MD) with a width of 100 cm between the chucks (distance between the nonwoven fabric web fixing points), a width of 2.5 cm in the transverse direction (CD), A split type composite fiber nonwoven fabric having a split type composite fiber fineness of 0.50 d was produced. The results of evaluating the obtained nonwoven fabric are shown in Table 1.

(Comparative Example 2)
A split type composite fiber nonwoven fabric was produced in the same manner as in Example 1. The obtained nonwoven fabric was subjected to a stretching treatment at a stretch ratio of 160% in the flow direction (MD) with a width of 100 cm between the chucks (distance between the nonwoven fabric web fixing points) and a width of 2.5 cm in the transverse direction (CD) using a tensile tester. However, evaluation was not possible because the nonwoven fabric broke during stretching.

（実験例３）
２種類の非相溶性の樹脂組合せにおいて、第一の樹脂を重量平均分子量Ｍｗ：１３３４００のポリ乳酸（三井化学（株）、商品名：ＬＡＣＥＡ、融点１６５℃）とし、第二の樹脂をＭＦＲ６０ｇ／１０分のポリプロピレン（Ｍｗ／Ｍｎ＝２．７）にアルキルポリオキシエチレンアルコール（ＣＨ_３ＣＨ_２（ＣＨ_２ＣＨ_２）_１３ＣＨ_２ＣＨ_２（ＯＣＨ_２ＣＨ_２）_２．５ＯＨ）を２．５重量％練り込み添加したものとし、それぞれ別個に押出機で溶融し、総セグメント数が１６である図１（ａ）のような断面形状となる分割型複合繊維紡糸用口金を用い第一樹脂と第二樹脂の重量比が５０／５０である分割型複合繊維を捕集ベルト上に堆積させ、次いで、これをエンボスロールで加熱加圧処理（エンボス面積率１８％、エンボス温度１００℃）して目付量が４０ｇ／ｍ２、構成繊維の繊度０．７５ｄの分割型複合繊維不織布を作製した。得られた不織布について、分割率（紡糸直後に測定）、吸水性、剛軟性、風合い、引張強度、リントフリー性を測定して評価した。結果を表２に示す。

(Experimental example 3)
In the two types of incompatible resin combinations, the first resin is polylactic acid (Mitsui Chemicals, trade name: LACEEA, melting point 165 ° C.) having a weight average molecular weight Mw: 133400, and the second resin is MFR 60 g / 10 minutes of polypropylene (Mw / Mn = 2.7) and _2.5 % of alkylpolyoxyethylene alcohol (CH ₃ CH ₂ (CH ₂ CH ₂ ) ₁₃ CH ₂ CH ₂ (OCH ₂ CH ₂ ) _2.5 OH) 1% by weight using a split type composite fiber spinning die having a cross-sectional shape as shown in FIG. A split type composite fiber having a weight ratio of the second resin of 50/50 is deposited on a collecting belt, and then heated and pressurized with an embossing roll (embossing area ratio 18%, embossing temperature). Basis weight 100 ° C.) to have to prepare a 40 g / m @ 2, the fineness 0.75d the constituent fibers splittable conjugate fiber nonwoven fabric. The obtained nonwoven fabric was evaluated by measuring the split ratio (measured immediately after spinning), water absorption, stiffness, texture, tensile strength, and lint-free properties. The results are shown in Table 2.

(Experimental example 4)
The nonwoven fabric obtained in Experimental Example 1 was stretched with a gear stretching machine with a gear pitch of 2.5 mm at a gear depth of 1.5 mm and a stretching ratio of 56% to produce a split-type composite fiber nonwoven fabric with a fineness of 0.4 d. Table 2 shows the evaluation results of the obtained nonwoven fabric.

(Experimental example 5)
The nonwoven fabric obtained in Experimental Example 1 was stretched with a gear stretching machine with a gear pitch of 2.5 mm at a gear depth of 2.5 mm and a stretching ratio of 124% to produce a split-type composite fiber nonwoven fabric with a fineness of 0.32d. Table 2 shows the evaluation results of the obtained nonwoven fabric.

(Experimental example 6)
The nonwoven fabric obtained in Experimental Example 1 was stretched with a gear stretching machine having a gear pitch of 2.5 mm at a gear depth of 3.0 mm and a stretching ratio of 160% to prepare a split-type composite fiber nonwoven fabric having a fineness of 0.27 denier. Table 2 shows the evaluation results of the obtained nonwoven fabric.

(Experimental example 7)
In the two types of incompatible resin combinations, the first resin is polylactic acid (Mitsui Chemicals, trade name: LACEEA, melting point 165 ° C.) having a weight average molecular weight Mw: 133400, and the second resin is MFR 60 g / For 10 minutes of polypropylene (Mw / Mn = 2.7), each melted separately by an extruder, and for the split type composite fiber spinning having a cross-sectional shape as shown in FIG. Using a die, a split type composite fiber having a weight ratio of the first resin to the second resin of 50/50 is deposited on a collection belt, and then this is heated and pressed with an embossing roll (embossing area). A split type composite fiber nonwoven fabric having a weight per unit area of 40 g / m 2 and a constituent fiber fineness of 0.88d was produced. The obtained nonwoven fabric was stretched at a stretching ratio of 56% in the same manner as in Experimental Example 2 with a tensile tester to produce a split type composite fiber nonwoven fabric having a fineness of 0.64d. Table 2 shows the evaluation results of the obtained nonwoven fabric.

(Experimental example 8)
In the two types of incompatible resin combinations, the first resin is polylactic acid (Mitsui Chemicals, trade name: LACEEA, melting point 165 ° C.) having a weight average molecular weight Mw: 133400, and the second resin is MFR 60 g / For 10 minutes of polypropylene (Mw / Mn = 2.7), each melted separately by an extruder, and for the split type composite fiber spinning having a cross-sectional shape as shown in FIG. Using a die, a split type composite fiber having a weight ratio of the first resin to the second resin of 50/50 is deposited on a collection belt, and then this is heated and pressed with an embossing roll (embossing area). A split type composite fiber nonwoven fabric having a weight per unit area of 40 g / m 2 and a constituent fiber fineness of 0.88d was produced. The obtained nonwoven fabric was evaluated by measuring the split ratio, water absorption, and texture. The results are shown in Table 2.

(Experimental example 9)
Using only polylactic acid (Mitsui Chemicals, Inc., trade name: LACEEA, melting point 165 ° C.) having a weight average molecular weight Mw: 133400, melt spinning is performed, and monocomponent fibers are deposited on the collecting belt, This was heated and pressurized with an embossing roll (embossing area ratio 18%, embossing temperature 130 ° C.) to produce a nonwoven fabric with a basis weight of 40 g / m 2 and a constituent fiber fineness of 2.76d. The obtained nonwoven fabric was evaluated by measuring water absorption, stiffness, texture, and tensile strength. The results are shown in Table 2.

(Experimental example 10)
MFR 60 g / 10 min polypropylene (Mw / MFR) containing 1.5% by weight of alkyl polyoxyethylene alcohol (CH ₃ CH ₂ (CH ₂ CH ₂ ) ₁₃ CH ₂ CH ₂ (OCH ₂ CH ₂ ) _2.5 OH) Using Mn = 2.7), melt spinning is performed by a melt blow method, and monocomponent fibers are deposited on a collecting belt to form a non-woven fabric having a basis weight of 40 g / m 2 and a constituent fiber fineness of 0.03d. Produced. The obtained nonwoven fabric was measured and evaluated for water absorption, stiffness, texture, tensile strength, and lint-free property. The results are shown in Table 2.

  The ultrafine fiber nonwoven fabric of the present invention includes medical and industrial wipers, masks, surgical gowns, packaging cloths, filters, absorbent articles, sanitary material surface materials such as disposable diapers and napkins, bed sheets, pillow covers, etc. It can be suitably used for sleeping bags and bedding inserts, carpets and artificial leather base fabrics, gardening and nursery fertilizer absorbers, building structure reinforcing fibers, liquid transport membranes, battery separators, and the like.

Claims (11)

Two different types of resins are discharged from a spinneret having a composite spinning nozzle and stretched to deposit split composite fiber-type long fibers having a predetermined fineness on a collection belt to form a nonwoven fabric, and further extend the tensile force. An ultrafine fiber nonwoven fabric having a fineness of 0.01 to 2.0 d (denier) obtained by addition, wherein the fineness of constituent fibers is uniform. The ultrafine fiber nonwoven fabric according to claim 1, wherein the standard deviation of the number of segments in which the variation in fineness forms the filament cross section of the ultrafine fiber is 6 or less. The ultrafine fiber nonwoven fabric according to claim 1 or 2, wherein at least two different resins are a polyolefin polymer and a polyester polymer. The ultrafine fiber nonwoven fabric according to claim 3, wherein the polyolefin polymer is a polypropylene polymer, and the polyester polymer is a polylactic acid polymer. The nonwoven fabric according to claim 1, wherein the fibers are produced by applying an extension force to a composite fiber made of at least two different resins. The ultrafine fiber nonwoven fabric according to claim 1, wherein the elongation force is applied by fixing the composite fiber nonwoven fabric at a point separated by a distance of 0.1 to 100 mm (millimeters) and uniformly stretching between the fixations. The nonwoven fabric according to claims 1 to 4, comprising at least two different resins and at least one resin comprising fibers having a hydrophilicity and a fineness of 0.01 to 2.0 d (denier). The ultrafine fiber nonwoven fabric according to claim 1, wherein the extension force is applied by gear drawing. Relationship between the draw ratio expressed by gear depth (H) mm and gear pitch (W) mm and the maximum elongation (E)% obtained in the test according to the strip method described in L-1096 in the gear drawing process The ultrafine fiber nonwoven fabric according to claim 1 satisfying the following mathematical formula.

A wiper comprising the split-type composite fiber nonwoven fabric according to any one of claims 1 to 8. A sanitary material comprising the split-type composite fiber nonwoven fabric according to any one of claims 1 to 8.

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