JP2009263839A - Polyester conjugated staple fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester conjugated staple fiber which uses a polyester having a low melting point but excellent in crystallinity to occupy at least a portion of fiber surface, can suitably be used for dry, wet type nonwoven fabric uses, can be processed at low temperature, when thermally adhered, and can give a product, such as a nonwoven fabric, good in dimensional stability and excellent in grade. <P>SOLUTION: Provided is the polyester conjugated staple fiber which comprises a polyester A comprising a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing 1,6-hexane diol in an amount of ≥50 mol%, containing a crystal-nucleating agent in an amount of 0.01 to 5.0 mass%, having a melting point of 100 to 150°C, and giving a DSC curve that exhibits temperature-fall crystallinity determined by DSC and satisfying a specific expression, and an amorphous polyester B having a melting point or a flow-starting temperature of ≥130°C, characterized by disposing the polyester A to occupy at least a portion of the fiber surface in the cross-sectional shape of a single fiber, and having a fiber length of 1.0 to 100 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a polyester containing a large amount of 1,6-hexanediol, a composite fiber arranged such that a polyester having a low melting point and excellent crystallinity occupies at least a part of the fiber surface, The present invention relates to a polyester composite short fiber excellent in thermal adhesiveness and suitable for use as a binder fiber.

  Synthetic fibers, especially polyester fibers, are indispensable as clothing and industrial materials due to their excellent dimensional stability, weather resistance, mechanical properties, durability, and recyclability. Many polyester fibers are used.

  2. Description of the Related Art In recent years, fiber structures such as nonwoven fabrics in which constituent fibers are bonded using binder fibers are frequently used in automobile interior materials and the like. Examples of fibers used for such binder fibers include core-sheath type composite short fibers having polyethylene terephthalate as a core and a polyethylene terephthalate copolymer copolymerized with an isophthalic acid component as a sheath.

  Since this fiber consists of a high melting point core and a low melting point sheath, the fiber form is maintained without melting the core during heat treatment, and only the sheath is melted to form an adhesive component. A nonwoven fabric excellent in strength can be obtained.

  However, since the polyethylene terephthalate copolymer obtained by copolymerizing the isophthalic acid component in the sheath is amorphous and does not exhibit a clear crystal melting point, softening starts at a temperature above the glass transition point. Further, when producing short fibers in which a polymer that does not exhibit a clear crystal melting point occupies the fiber surface, if the heat treatment temperature is set to 100 ° C. or higher in the drawing / heat treatment step, the fibers are melted and glued, which is difficult to implement. For this reason, the drawing and heat treatment steps are performed at a low temperature, and the obtained short fibers have a high heat shrinkage rate.

  And when such short fibers are used as binder fibers, the shrinkage at the time of heat bonding treatment is large, the dimensional stability when obtaining a nonwoven fabric product is deteriorated, and the product is inferior in formation and uniformity. There was a problem, and when it was used in a high temperature atmosphere, there was a problem that the adhesive strength was lowered and deformed.

  As a solution to the above problem, Patent Document 1 discloses a core-sheath type composite fiber. This fiber has a core sheath in which polyethylene terephthalate is disposed in the core portion and a polyester copolymer obtained by copolymerizing a terephthalic acid component, an aliphatic lactone component, an ethylene glycol component, and a 1,4-butanediol component is disposed in the sheath portion. Type composite fiber.

  In this composite fiber, the sheath copolymer is crystalline and has a clear melting point. Therefore, the drawing and heat treatment steps for obtaining the short fiber can be performed at a high temperature, and a short fiber having a low heat shrinkage rate is obtained. be able to. For this reason, it is possible to obtain a product such as a non-woven fabric with good dimensional stability without shrinkage during the thermal bonding treatment, and to be a product excellent in heat resistance when used in a high temperature atmosphere. it can.

  However, this copolyester has a melting point in the range of 150 to 200 ° C. and is not yet in the low melting point region, and it is necessary to increase the processing temperature when performing the thermal bonding treatment, which is costly. Was also disadvantageous.

  Moreover, there exists an airlaid method as a method of obtaining a dry nonwoven fabric using a short fiber. This airlaid method employs a method in which fibers are defibrated and conveyed in an air flow, passed through a screen having a wire mesh or pores, and then dropped and deposited on a wire mesh.

Even in the airlaid method, there is a demand for short fibers made of polyester having excellent crystallinity and a low melting point, and capable of obtaining a nonwoven fabric with high dimensional stability.
JP 2006-118066 A

  The present invention solves the above problems, and uses a polyester having a low melting point and excellent crystallinity, and is arranged so as to occupy at least a part of the fiber surface. It can be produced with good performance, can be used suitably for air-laid processes, dry and wet non-woven fabrics, and can be processed at low temperatures when thermally bonded, with excellent dimensional stability and excellent quality. Another object of the present invention is to provide a polyester composite short fiber from which a product such as a non-woven fabric can be obtained.

The inventors of the present invention have arrived at the present invention as a result of studies to solve the above problems. That is, the present invention comprises a dicarboxylic acid component mainly composed of terephthalic acid and a diol component of 1,6-hexanediol of 50 mol% or more, and contains 0.01 to 5.0% by mass of a crystal nucleating agent. The melting point is 100 to 150 ° C., and the DSC curve indicating the temperature-falling crystallization obtained from DSC satisfies the following formula (1): the melting point or the flow starting temperature is 130 ° C. or higher, and the melting point of the polyester A It is a composite fiber composed of higher polyester B, and is arranged such that polyester A occupies at least a part of the fiber surface in the cross-sectional shape of a single yarn, and the fiber length is 1.0 to 100 mm. The characteristic polyester composite staple fiber is used as a gist.
Formula (1) ... b / a ≧ 0.05 (mW / mg · ° C.)
Note that a is the temperature A1 (° C.) of the intersection between the tangent line and the baseline having the maximum inclination in the DSC curve indicating the temperature-falling crystallization, and the temperature A2 (° C.) of the intersection of the tangent line and the baseline having the minimum inclination. B) is the difference (B1-B2) between the baseline heat quantity B1 (mW) and the peak top heat quantity B2 (mW) at the peak top temperature (mg) The value divided by.

  The polyester composite short fiber of the present invention has a low melting point and is excellent in crystallinity, and particularly by using polyester A having a high crystallization speed when the temperature is lowered, and is arranged so as to occupy at least a part of the fiber surface. In No. 1, there is no welding between single yarns, and in the drawing and heat treatment steps, heat treatment can be performed at a high temperature, and a short fiber having a low dry heat shrinkage can be obtained.

  Further, since polyester A occupies at least a part of the fiber surface, mechanical crimps can be favorably imparted, so that crimps having a specific shape can be imparted. By using short fibers having such a specific shape of crimp, fibers are produced in web forming processes such as air flow, feeding of short fibers by a carding machine, dispersion, defibration, laminating process, etc. in the nonwoven fabric manufacturing process. It is possible to obtain a short fiber non-woven fabric that does not generate lumps, has excellent uniformity, high quality, and high bulkiness. In particular, it can be suitably used when obtaining a nonwoven fabric by the airlaid method, and since it can prevent the generation of static electricity in the production process, there is no generation of fiber mass or occurrence of fusion, and uniformity and bulkiness. An excellent airlaid nonwoven fabric can be obtained.

  Furthermore, when the polyester composite short fiber of the present invention is used as a binder fiber, it can be processed at a low temperature when thermally bonded, is advantageous in terms of cost, and has excellent thermal adhesiveness. Furthermore, since the dry heat shrinkage rate is low, it is possible to obtain a product such as a nonwoven fabric having a small shrinkage at the time of thermal bonding treatment, good dimensional stability, and excellent texture and quality.

  Hereinafter, the present invention will be described in detail. The polyester composite short fiber of the present invention is a composite fiber composed of polyester A and polyester B, and is arranged such that polyester A occupies at least a part of the fiber surface. That is, the short fibers of the present invention may be multifilaments or monofilaments, but polyester A occupies at least a part of the fiber surface in the cross-sectional shape of a single yarn (cross-sectional shape cut perpendicularly along the fiber axis direction). It is what.

  Examples of such a shape include a side-by-side type, an eccentric core-sheath type, and a multi-layer type. Among them, in a cross-sectional shape of a single yarn, polyester A is a sheath and polyester B is a core. The shape is preferred.

  First, polyester A will be described. Polyester A is a copolyester having a melting point of 100 to 150 ° C. composed of a dicarboxylic acid component containing terephthalic acid as a main component and a diol component of 1,6-hexanediol of 50 mol% or more.

  Polyester A has a melting point (Tm) of 100 to 150 ° C, preferably 110 to 140 ° C. When Tm is less than 100 ° C., a product such as a nonwoven fabric obtained by using the composite short fiber of the present invention is inferior in thermal stability (heat resistance) when used in a high temperature atmosphere. On the other hand, if the temperature exceeds 150 ° C., it is necessary to increase the heat bonding processing temperature when obtaining the product, which is inferior in workability and economy. Further, it is not preferable because the quality and texture of the product obtained by the heat treatment are impaired.

  Polyester A has terephthalic acid as a main component as a dicarboxylic acid component, and terephthalic acid (hereinafter referred to as TPA) is preferably 60 mol% or more, more preferably 80 mol% or more. If the TPA is less than 60 mol%, the melting point of the polymer is not within the scope of the present invention, and the crystallinity tends to be lowered, which is not preferable.

  In addition, as copolymerization components other than TPA, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid are used as long as the effects are not impaired. Saturated aliphatic dicarboxylic acids exemplified by acids, 1,4-cyclohexanedicarboxylic acid, dimer acids and the like, or ester-forming derivatives thereof, unsaturated aliphatic dicarboxylic acids exemplified by fumaric acid, maleic acid, itaconic acid and the like Aromatic dicarboxylic acids exemplified by these ester-forming derivatives, phthalic acid, isophthalic acid, 5- (alkali metal) sulfoisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, etc. These ester-forming derivatives can be used.

  As the diol component, 1,6-hexanediol (hereinafter referred to as HD) is 50 mol% or more, and as other components, ethylene glycol (hereinafter referred to as EG) or 1,4-butanediol (hereinafter referred to as HD). BD) is preferably used. In the diol component, HD is 50 mol% or more, and preferably 60 to 95 mol%. When HD is less than 50 mol%, the melting point exceeds 150 ° C.

  When EG or BD is used together with HD as the diol component, EG or BD is preferably 5 to 50 mol%, more preferably 5 to 40 mol% in the diol component.

  Furthermore, the diol component includes other copolymer components other than HD, EG and BD, as long as the properties are not impaired, 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol, tetra For ethylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, polyethylene glycol, polytrimethylene glycol, polytetramethylene glycol, etc. Exemplified aliphatic glycols, hydroquinone, 4,4′-dihydroxybisphenol, 1,4-bis (β-hydroxyethoxy) benzene, bisphenol A, 2,5-naphthalenediol, ethylene glycol Can be used aromatic glycols Sid is exemplified such as glycol was added.

  And polyester A contains 0.01-5.0 mass% of crystal nucleating agents, and it is preferable to contain 0.5-3.0 mass% especially.

  Polyester A has crystallinity due to the copolymer composition as described above, but can contain a crystal nucleating agent to improve the crystallization rate during cooling, which will be described later. The expression (1) to be satisfied can be satisfied. And, when the polyester A is made into a fiber, it is possible to heat-treat at a high temperature in the drawing and heat treatment process without causing welding between the single yarns in the melt spinning process. can do.

  If the content of the crystal nucleating agent is less than 0.01% by mass, the crystallization speed at the time of temperature reduction cannot be improved, and it becomes difficult for the polyester A to satisfy the formula (1) described later. On the other hand, if it exceeds 5.0 mass%, the content of the crystal nucleating agent is excessively increased, and the operability during spinning and stretching is deteriorated. In addition, the deterioration in operability increases the variation in yarn quality and increases the dry heat shrinkage of the fibers.

  As the crystal nucleating agent, it is preferable to use inorganic fine particles, polyolefin, sulfate or the like.

As the inorganic fine particles, those mainly composed of silicon oxide such as talc are preferable, and inorganic fine particles having an average particle size of 3.0 μm or less or a specific surface area of 15 m ² / g or more are preferably used. When the average particle diameter or specific surface area is not satisfied, the function as a crystal nucleus is poor, and it is difficult for the polyester A to satisfy the formula (1) described later.

  The polyolefin contained as a crystal nucleating agent melts in the reaction system, so the shape is not particularly limited. For example, a chip-like one having a particle size of about 2 mm or a wax-like one having a particle size of several μm It may be.

  Examples of polyolefins include olefin homopolymers such as polyethylene, polypropylene, poly-1-butene, polymethylpentene, and polymethylbutene, and propylene / ethylene random copolymers. Polyethylene, polypropylene, poly-1- Butene and propylene / ethylene random copolymers are particularly preferred. When the polyolefin is a polyolefin obtained from an olefin having 3 or more carbon atoms, it may be an isotactic polymer or a syndiotactic polymer.

  Examples of the sulfate to be contained as a crystal nucleating agent include lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, barium sulfate, calcium sulfate, and aluminum sulfate. And magnesium sulfate are preferred.

  As a method for adding these crystal nucleating agents, they may be added at an arbitrary stage when the polyester is produced in the form of powder or in the form of a diol slurry. For example, it may be added at the time of esterification or transesterification, or may be added at the stage of polycondensation reaction. Among these, in order to improve the effect as a crystal nucleating agent, it is preferable to add in a slurry state or a dissolved state in a glycol such as ethylene glycol.

  In addition, polyester A contains a stabilizer such as a phosphate ester compound and a hindered phenol compound, a cobalt compound, a fluorescent brightening agent, a color tone improver such as a dye, and a dioxide dioxide within a range not impairing the effects of the present invention. One or more kinds of various additives such as matting agents such as titanium, plasticizers, pigments, antistatic agents, flame retardants and dyeing agents may be added.

Polyester A has a DSC curve showing temperature-fall crystallization determined from DSC satisfying the following formula (1), and it is preferable that b / a ≧ 0.06 among them. On the other hand, the larger b / a, the better the crystallinity when the temperature is lowered, but in order to achieve the intended effect of the present invention, b / a should be 2.0 or less, especially 0.5 or less. preferable.
b / a ≧ 0.05 (mW / mg · ° C.) (1)

  The DSC curve showing the melting temperature of polyester A in the present invention and the temperature-falling crystallization obtained from DSC is a temperature range of −20 ° C. to 250 ° C. in a nitrogen stream using a differential scanning calorimeter (Diamond DSC) manufactured by PerkinElmer. Measured at a temperature rising (falling) rate of 20 ° C./min and a sample amount of 2 mg (mass of short fibers).

  Said b / a is calculated | required from the DSC curve which shows the temperature-fall crystallization calculated | required from DSC. At this time, two peaks of polyester A and polyester B forming the fiber appear, but the DSC curve of the peak appearing on the low temperature side is that of polyester A.

  As shown in FIG. 1, in the DSC curve of polyester A, a is the temperature A1 (° C.) at the intersection of the tangent line and the base line having the maximum inclination in the DSC curve indicating the temperature-falling crystallization, and the inclination is minimum. Is the difference (A1-A2) between the temperature A2 (° C.) at the intersection of the tangent and the base line, and b is the heat amount B1 (mW) of the base line and the heat amount B2 (mW) of the peak top at the peak top temperature. (B1-B2) divided by the amount of sample (mg).

  b / a is an index representing the crystallinity when the temperature is lowered, and the higher the b / a value, the faster the crystallization rate, and vice versa, the closer to 0, the slower the crystallization rate. When b / a is less than 0.05 (mW / mg · ° C.), the crystallization rate is low, so that welding between single yarns occurs during melt spinning, and the spinning operability deteriorates. Further, when the heat treatment temperature in the drawing / heat treatment step is increased, the fibers are melted and glued, and heat treatment at a high temperature cannot be performed, so that a fiber having a low heat shrinkage rate cannot be obtained.

  As described above, b / a can be within the range specified in the present invention by setting the copolymer composition of polyester A to a specific value and the content of the crystal nucleating agent within the above range. it can.

  Next, polyester B will be described. Polyester B has a melting point or flow starting temperature of 130 ° C. or higher and higher than the melting point of polyester A. The polyester B may be crystalline like the polyester A, or may be amorphous. In the case of a crystalline material, the melting point is set to 130 ° C. or higher.

  The polyester composite short fiber of the present invention is a binder fiber in which only polyester A is melted by thermal bonding treatment to make polyester A a low melting point polyester and polyester B a higher melting point polyester than polyester A. It is suitable to use. That is, when obtaining a fiber structure such as a dry nonwoven fabric or a wet nonwoven fabric using the polyester composite short fiber of the present invention, other fibers having a melting point higher than that of the polyester A are used as main fibers, and the polyester A is used as an adhesive component. Polyester B is preferably used as a main fiber together with other fibers without being melted.

  The upper limit of the melting point or flow start temperature of the polyester B is not particularly limited, but is preferably 290 ° C. or lower for the purpose of avoiding thermal decomposition of the polyester A during melt spinning. Further, the melting point or flow start temperature of polyester B is higher than the melting point of polyester A. However, as described above, in order to use polyester B as a main fiber together with other fibers without melting it, the melting point of polyester A is higher. It is preferably 20 ° C. or higher, and more preferably 30 ° C. or higher.

  However, since polyester A has a low melting point, polyester B also has a relatively low melting point or flow starting temperature, so that welding between single yarns and yarn breakage do not occur at the time of melt spinning, and operability is good. It becomes possible to perform melt spinning. Therefore, it is preferable that it is 135-220 degreeC especially, and it is more preferable that it is 140-200 degreeC. And it is preferable that it is 20-90 degreeC higher than melting | fusing point of polyester A, and it is preferable that it is 30-80 degreeC above all.

  If the melting point or flow starting temperature of polyester B is less than 130 ° C. or lower than the melting point of polyester A, polyester B will also melt at the time of thermal bonding treatment when polyester A is melted, and polyester B will be the main fiber along with other fibers. It becomes difficult to use as. On the other hand, if the melting point or the flow start temperature is too low, sufficient heat treatment cannot be performed in the stretching and heat treatment steps, and it becomes difficult to reduce the dry heat shrinkage rate of the short fibers.

  The polyester B is preferably composed mainly of polyalkylene terephthalate such as polyethylene terephthalate (PET), polybutylene terephthalate, polytrimethylene terephthalate. And in order to set it as the above melting | fusing point or a flow start temperature, it is preferable to copolymerize the following components.

  Examples of copolymer components include isophthalic acid (hereinafter referred to as IPA), aromatic dicarboxylic acids such as 5-sulfoisophthalic acid, aliphatic dicarboxylic acids such as adipic acid, succinic acid, suberic acid, sebacic acid, and dodecanedioic acid, And aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxypentanoic acid, hydroxyheptanoic acid, Examples thereof include hydroxycarboxylic acids such as hydroxyoctanoic acid and aliphatic lactones such as ε-caprolactone.

  Among these, as polyester B, it is preferable to use a copolyester containing a TPA component, an EG component, and at least one component of a BD component, an aliphatic lactone component, and an adipic acid component from the viewpoint of melting point and crystallinity. Since these polyesters are excellent in crystallinity, when used together with polyester A having high crystallinity, the spinning operability becomes better, and it becomes possible to process at high temperature during stretching and heat treatment. It becomes easy to obtain.

  First, when the aliphatic lactone component is copolymerized, the copolymerization amount is preferably 20 mol% or less, more preferably 10 to 20 mol%, based on the total acid component. When the proportion of the aliphatic lactone component is small, the crystallinity is improved, but the melting point tends to be high. On the other hand, if it exceeds 20 mol%, the crystallinity is lowered, the glass transition temperature is liable to be lowered, and welding between single yarns is likely to occur at the time of spinning, so that the spinning property is liable to deteriorate.

  The aliphatic lactone component is preferably a lactone having 4 to 11 carbon atoms, and particularly preferred lactone includes ε-caprolactone.

  Next, when copolymerizing a BD component, it is preferable that a copolymerization amount shall be 40-80 mol% with respect to all the glycol components. When the copolymerization amount is less than 40 mol% or exceeds 80 mol%, the melting point tends to be high.

  When the adipic acid component is copolymerized, the copolymerization amount is preferably 20 mol% or less, more preferably 10 to 20 mol%, based on the total acid component. When the copolymerization amount of the adipic acid component is less than 10 mol%, the crystallinity is improved, but the melting point tends to be high. On the other hand, when it exceeds 20 mol%, the crystallinity is lowered, the glass transition temperature is liable to be lowered, and welding between single yarns is likely to occur at the time of spinning, so that the spinning property is liable to be deteriorated.

  Moreover, it is also preferable to use PET copolymerized with isophthalic acid as the polyester B, and among them, those obtained by copolymerizing 5 to 30 mol% of isophthalic acid are preferable. When the copolymerization amount of isophthalic acid is less than 5 mol%, the flow start temperature tends to increase. On the other hand, when it exceeds 30 mol%, the flow start temperature becomes low and tends to be less than 130 ° C.

  In the polyester B, as long as the effects of the present invention are not impaired, a stabilizer such as a phosphate ester compound or a hindered phenol compound, a cobalt compound, a fluorescent whitening agent, a color tone improving agent such as a dye, One type or two or more types of various additives such as matting agents, plasticizers, pigments, antistatic agents, flame retardants, and dyeing agents may be added.

  The composite ratio (mass ratio) of polyester A and polyester B of the polyester composite short fiber of the present invention is preferably 20/80 to 80/20, and more preferably 30/70 to 70/30.

The polyester composite short fiber of the present invention has a fiber length of 1.0 to 100 mm, preferably 3.0 to 80 mm, and can be suitably used when obtaining a product such as a nonwoven fabric as a binder fiber. . When the fiber length is less than 1.0 mm, the fibers are fused or glued by heat at the time of cutting. When the fiber length exceeds 100 mm, the defibration property of the card machine is deteriorated, and the product such as the obtained nonwoven fabric is inferior in formation and uniformity.
The fiber length is measured based on the JIS L1015 8.4.1A method.

  The polyester composite short fiber of the present invention preferably has a single yarn fineness of 0.1 to 30 dtex. When the single yarn fineness is less than 0.1 dtex, single yarn cutting frequently occurs in the spinning and drawing processes, the operability deteriorates and the strength of the resulting nonwoven fabric tends to be inferior. On the other hand, when the single yarn fineness exceeds 30 dtex, cooling of the spun yarn becomes insufficient, and the quality of the obtained fiber tends to be lowered.

  The cross-sectional shape of the single yarn of the polyester composite short fiber of the present invention is not particularly defined, and is not limited to a round shape, but a flat shape, a trilobal shape, a hexaloval shape, a W shape, an H shape, etc. A polygonal shape such as a polygonal shape or a hollow shape may be used.

  Furthermore, the polyester composite short fiber of the present invention is a short fiber having a crimp length that satisfies the following condition (2), a fiber length of 1.0 to 30 mm, and a single yarn fineness of 0.3 to 20 dtex. By doing so, it is particularly suitable for obtaining a dry nonwoven fabric by the airlaid method. At this time, the preferable fiber length is 2.0 to 20 mm, more preferably 5.0 to 15 mm. When the fiber length is less than 1.0 mm, the fibers are melted or glued by heat at the time of cutting. When the fiber length exceeds 30 mm, a fiber lump is likely to be generated, and the resulting fiber structure such as a nonwoven fabric tends to be inferior.

  The crimp satisfying the condition (2) is preferably applied by the stuffing box method, the indentation heating gear method, or the like.

That is, as the condition (2), in the polyester composite short fiber of the present invention, the crimped form imparted to the single yarn constituting the short fiber is adjacent to the apex of the peak at the maximum peak of the crimp. The ratio (H / L) between the height (H) of the triangle connecting the two bottom points of the valley and the length (L) of the base satisfies the following expression (3).
(3) Formula: 0.01T + 0.10 ≦ H / L ≦ 0.02T + 0.25
T is the number of decitex (dtex) of single yarn fineness

  In this case, the single yarn fineness is preferably 0.3 to 20 dtex, more preferably 0.5 to 15 dtex, and further preferably 1.0 to 10 dtex. The single yarn fineness is measured based on the JIS L1015 8.5.1B method.

  When a dry nonwoven fabric is obtained, particularly when it is produced by the airlaid method, static electricity is generated more. As an apparatus used in this airlaid method, for example, as disclosed in Japanese Patent Laid-Open No. 5-9813, a plurality of rotating cylinders are housed in a housing, and these cylinders are rotated at a high speed to positively move to the periphery of the cylinder. An apparatus that can generate an air flow and blow the fiber component in a predetermined direction by the air flow can be mentioned. In the web formation by the airlaid method (short fiber defibration, transport, dispersion, and lamination processes), since an air flow is actively generated, the fibers are rubbed with each other. The generation of static electricity is also increased by friction with the device (metal member).

  When considering the problem of static electricity, there are many crimps, and the larger it is, the easier it is to save electricity in shape. That is, if the fiber is crimped, it exhibits a three-dimensional solid shape, so that static electricity tends to accumulate as the three-dimensional space portion increases. On the other hand, as the flat state without crimping becomes flat, it becomes more flat and less likely to accumulate static electricity. However, the number of contact points (surfaces) between fibers or between fibers and metal increases, and the generation of static electricity due to friction increases. .

  Therefore, by making the crimped form specific, in each process of web formation (defibration, transport, dispersion, laminating process), it is difficult for static electricity to be generated due to friction between fibers, and between fibers and metal, and It is difficult to accumulate the generated static electricity, and the short fibers are gathered together to form a fiber lump.

  The crimped form of the single yarn of the polyester composite short fiber of the present invention will be described with reference to FIG. In the crimped form of single yarn, a triangle is formed by connecting the apex P of the peak at the maximum peak of the crimped portion and the bottom points Q and R of the adjacent valleys, and the height (H) of this triangle And the ratio (H / L) of the length (L) of the base side satisfies the above expression (3). Here, when there are a plurality of peak portions in the fiber length of the short fiber of the present invention, the maximum peak portion means the one having the highest peak height (H).

  When H / L is too large, the space portion becomes large in the three-dimensional shape of the fiber, and it is easy to accumulate static electricity, and the fiber is entangled easily. On the other hand, if H / L is too small, the shape of the fiber is almost flat, and the number of contact points (surfaces) between the fibers or between the fiber and the metal increases. It is not preferable.

  In addition, the measurement of H / L is as follows. First, 1 g of short fibers are collected, and 20 single fibers are arbitrarily extracted therefrom. Then, an enlarged photograph (about 10 times) is taken with respect to the taken out single fiber, and as described above from the photograph, two points of the bottom points Q and R of the valley part adjacent to the peak part P at the peak part are adjacent to the maximum peak part. A triangle is formed by tying, the height (H) of the triangle and the length (L) of the base are measured, and the ratio (H / L) is calculated. In this way, 20 single fibers are measured and the average value is taken.

  Furthermore, the polyester composite short fiber of the present invention satisfies 0.1T + 3.8 ≦ crimp number ≦ 0.3T + 7.3 (4) [T is the decitex (dtex number of single yarn fineness)]. Is preferred. The number of crimps is measured and calculated based on JIS L1015 8.12.1. In addition, when the fiber length is short in the measurement of the number of crimps, it is measured on the fiber before cutting after the crimping and is converted into the number per 25 mm fiber length.

  When the number of crimps exceeds the upper limit of the formula (4), the number of crimped portions that become space portions due to a three-dimensional solid shape increases, and fibers are fed in the process of feeding, dispersing, defibrating, and laminating short fibers by airflow. Static electricity generated between them is easily accumulated, and fibers are easily entangled with each other. On the other hand, when the value is smaller than the lower limit of the expression (4), the number of crimped portions is reduced, so that the shape of the fiber is almost flat, and the contact points (surfaces) between the fibers or the fiber and the metal are increased. It is easy to occur and a thread-like fiber lump is generated, which is not preferable.

  Furthermore, the polyester composite short fiber of the present invention satisfies 0.8T + 0.3 ≦ crimp rate ≦ 1.0T + 4.9 (5) [T is the decitex (dtex number of single yarn fineness)]. Is preferred. This crimp rate is measured and calculated based on JIS L1015 8.12.2. In addition, when the fiber length is short in the measurement of the crimp rate, it is difficult to measure, and after the crimp is applied, the fiber is measured before being cut and converted to the number per 25 mm fiber length.

  When the crimp rate is higher than the upper limit of the formula (5), the space portion due to the three-dimensional solid shape increases or becomes large, and is generated between fibers in the short fiber feeding, dispersion, defibration, and laminating processes. This is not preferable because it tends to accumulate static electricity and the fibers tend to be entangled with each other. On the other hand, when the value is lower than the lower limit of the formula (5), the shape of the fiber is almost flat, and the contact points (surfaces) between the fibers or the fiber and the metal increase, so that static electricity is easily generated. A fiber lump is formed, which is not preferable.

  The polyester composite short fiber of the present invention is suitable for production by the airlaid method by adopting the crimped form as described above, but may be used for either a dry nonwoven fabric or a wet nonwoven fabric.

  In dry nonwoven fabrics, according to the airlaid method, fibers can be bonded together only by heat treatment with hot air, and it is possible to easily obtain nonwoven fabrics. The crimping process can be omitted, which is advantageous in terms of cost.

  Also in wet nonwoven fabrics, the single fibers are scattered and the number of contact points (surfaces) between the single fibers is small, so that the fibers are not easily focused. Therefore, a wet nonwoven fabric having excellent uniformity and sufficient bulkiness is obtained. be able to.

  Furthermore, the polyester composite short fiber of the present invention preferably has a dry heat shrinkage rate of (Tm-30) ° C. of 7% or less, particularly 6% or less when the melting point of the polyester A constituting the fiber is Tm. It is preferable that it is 5% or less.

  The dry heat shrinkage in the present invention is measured by the dry heat shrinkage measurement method in the measurement of the shrinkage of JIS L-1015. The initial load is 50 mg / dtex, the gripping interval is 25 mm, and the treatment temperature is ( Tm-30) Measured as ° C. In addition, when the fiber length is short in the measurement of the dry heat shrinkage rate, it is measured on the fiber before cutting after crimping.

  (Tm-30) By making the dry heat shrinkage rate at 7 ° C. or less 7% or less, products such as non-woven fabrics obtained using this short fiber have low heat shrinkage during heat bonding treatment and good dimensional stability. Can be used, and has excellent formation and flexibility. On the other hand, when the dry heat shrinkage at (Tm-30) ° C. exceeds 7%, it is difficult to achieve such an effect.

  When producing short fibers using polyester that does not exhibit a clear crystal melting point as in the prior art, welding between single yarns occurs during melt spinning, and if the heat treatment temperature is 100 ° C. or higher in the drawing and heat treatment steps, Fiber melting and sticking occur, making implementation difficult. Therefore, the drawing and heat treatment steps are performed at a low temperature, and the obtained short fibers have a high dry heat shrinkage rate. For this reason, when a nonwoven fabric is produced using such short fibers as binder fibers, the shrinkage when the web is thermally bonded increases, and the resulting nonwoven fabric has a large web shrinkage ratio compared to the area of the web before the thermal bonding treatment. It becomes inferior to formation and uniformity.

  Since the polyester composite short fiber of the present invention has a low melting point and high crystallinity, and particularly polyester A having a high temperature-falling crystallization rate is arranged so as to occupy at least a part of the fiber surface, No welding between single yarns occurs. Then, after melt spinning, heat treatment can be performed at a high temperature in the drawing / heat treatment step, so that the dry heat shrinkage can be reduced. Furthermore, mechanical crimping having a specific shape can be easily applied by the stuffing box method, the indentation heating gear method, or the like.

  Next, the short fiber nonwoven fabric using the polyester composite short fiber of the present invention will be described. The composite staple fiber of the present invention can be used for a dry nonwoven fabric or a wet nonwoven fabric as described above, and it is preferable that the composite staple fiber of the present invention is a binder fiber and other fibers are main fibers. And it is preferable to make content of the composite short fiber of this invention in a nonwoven fabric into 10-90 mass%, and it is preferable to set it as 20-70 mass% especially. The basis weight is not particularly limited.

  And in the short fiber nonwoven fabric, the composite short fiber of the present invention constitutes a web, but at least a part thereof is melted to become an adhesive component for adhering the main fibers. Among them, it is preferable that only the polyester A is melted to be an adhesive component by the thermal bonding treatment, and the polyester B is not melted but becomes a main fiber together with other fibers.

  When the dry nonwoven fabric is obtained by the airlaid method, the polyester composite short fiber of the present invention has a specific crimped shape that satisfies the condition (2), thereby preventing the fibers from being entangled in the nonwoven fabric production process and uniform. Web. And since the main fiber and the polyester composite short fiber of the present invention form a uniform web at the stage of the web, when the polyester A constituting the composite short fiber of the present invention is melted by the heat bonding treatment to become an adhesive component Adheres the intersection of the short fibers forming the web well.

  When the content of the composite short fiber of the present invention in the nonwoven fabric is less than 10% by mass, the adhesive component is reduced, so that the adhesion after the thermal bonding treatment becomes insufficient, and a nonwoven fabric having sufficient mechanical properties is obtained. It tends to be difficult. On the other hand, when the content exceeds 90% by mass, the adhesive component increases, so that the flexibility and bulkiness tend to be poor.

  In addition, in the short fiber nonwoven fabric using the composite short fiber of the present invention, as other fibers used as the main fiber, synthetic fibers made of a thermoplastic resin made of polyester, polyamide, etc. can be used, among which alkylene terephthalate. A polyester mainly composed of units and having a melting point of 220 to 280 ° C. is preferable. Specific examples include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Among these, PET is preferable. Further, these polyesters may be copolymer polyesters obtained by copolymerizing one or more of the following copolymer components as required.

  Examples of the copolymer component include terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, bisphenol S, bisphenol A, cyclohexanedimethanol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, Examples include polyethylene glycol.

Next, the manufacturing method of the polyester composite short fiber of this invention is demonstrated using an example.
First, a dicarboxylic acid component and a diol component are esterified or transesterified, and a crystal nucleating agent is added to perform a polycondensation reaction. When the polyester reaches a predetermined intrinsic viscosity in the polycondensation reaction, it is discharged into a strand, cooled, and cut into chips. Next, the chips (polyester A) and polyester B are supplied to an ordinary composite melt spinning apparatus to perform melt spinning. After spinning and solidifying the spun yarn, it is once stored in a container. Then, the yarns are converged to form a yarn bundle of about 1 to 100 ktex, and stretched at a stretching ratio of about 2 to 6 times between rollers. Subsequently, heat treatment is performed at 100 to 120 ° C., and after applying a finishing oil, mechanical crimping is applied with an indentation-type crimper or the like, and cut into a target fiber length to obtain a polyester composite short fiber. In order to obtain a crimped form that satisfies the condition (2), the stretching conditions (magnification, temperature) and the crimping conditions (nip pressure, staffin pressure) in a crimping device such as a push-in crimper are adjusted. Is possible.

  Next, about the manufacturing method of the short fiber nonwoven fabric using the polyester composite short fiber of this invention, each of a dry-type nonwoven fabric and a wet nonwoven fabric is demonstrated using an example. An example in which the polyester composite short fiber of the present invention is used as a binder fiber and another polyester short fiber is used as a main fiber for both dry nonwoven fabric and wet nonwoven fabric will be described.

  First, in the case of a dry nonwoven fabric (airlaid method), using the simple airlaid tester shown in FIG. 3, from the sample input blower 13, the composite short fiber of the present invention and the polyester short fiber as the main fiber are charged at an arbitrary ratio, Each set of five first defibrating blades 11 and second defibrating wings 12 is rotated by a defibrating blade rotating motor 15 via a sprocket 16 for rotating the defibrating blades, and is scattered and dropped. While dropping the short fibers, they are sucked by the suction box 14 at the bottom, and deposited on the cotton collecting conveyor 17 that moves in the direction of the arrow to create a web. Then, heat treatment is performed in the heat treatment machine 18 downstream, and at least a part of the polyester A of the composite short fiber is melted to be an adhesive component, and the fiber and the main fiber (polyester short fiber) which are the polyester B constituting the composite short fiber ) To obtain a dry nonwoven fabric. The basis weight adjustment of the nonwoven fabric is performed by changing the moving speed of the cotton collection conveyor 17.

  Moreover, in the case of a wet nonwoven fabric, the composite short fiber of this invention and the polyester short fiber used as a main fiber are thrown into a pulp disaggregator in arbitrary ratios, and are stirred. Thereafter, the obtained sample is transferred to a paper machine, and after adding a dispersion oil mainly composed of an alkyl phosphate metal salt, stirring is performed with an accompanying stirring blade to make a paper, thereby obtaining a wet nonwoven web. The paper-made wet non-woven web is heat-treated with a hot air drier to melt at least a part of the polyester A of the composite short fiber as an adhesive component, and the fiber and the main fiber (polyester short) constituting the composite short fiber. Fiber) is bonded to obtain a wet nonwoven fabric.

Next, the present invention will be specifically described using examples. The measurement and evaluation methods for various characteristic values in the examples are as follows.
(A) Average particle size of inorganic fine particles The average particle size of the sample in ethylene glycol was measured using a particle size distribution analyzer (SALD-2000) manufactured by Shimadzu Corporation.
(B) Specific surface area of inorganic fine particles Measured by BET method.
(C) Intrinsic viscosity [η]
Measurement was carried out based on a conventional method under the conditions of a sample concentration of 0.5% by mass and a temperature of 20 ° C. using an equal mass mixture of phenol and ethane tetrachloride as a solvent.
(D) Melting point of polyester A, DSC curve showing temperature drop crystallization determined from DSC Measured by the above method.
(E) Melting point of polyester B Using a differential scanning calorimeter (Diamond DSC manufactured by Perkin Elmer Co.), the temperature giving the extreme value of the melt absorption curve measured at a heating rate of 20 ° C./min was defined as the melting point.
(F) Flow start temperature of polyester B Using a flotester (Shimadzu CFT-500 type), the temperature was increased at a rate of 10 ° C./minute from an initial temperature of 50 ° C. under a load of 9.8 MPa and a nozzle diameter of 0.5 mm. The temperature was determined as the temperature at which the polymer began to flow out of the die.
(G) Polymer Composition of Polyester A and Polyester B The obtained polyester composite short fiber was dissolved in a mixed solvent having a volume ratio of 1/20 of deuterated hexafluoroisopropanol and deuterated chloroform, and LA- 1H-NMR was measured with a 400-type NMR apparatus, and determined from the integrated intensity of the proton peak of each copolymer component in the obtained chart.
(H) Spinning operability The following two stages were evaluated according to the spinning conditions.
A: The number of cut yarns during spinning is 1 / ton or less, and there is no welding between single yarns.
X: The number of cut yarns during spinning exceeds 1 / ton or welding between single yarns occurs.
(I) Dry heat shrinkage (%) of polyester composite short fiber
Measurement was performed by the method described above.
(J) Generation of fiber lump The resulting composite short fiber was evaluated for the generation of fiber lump using the simple air flow agitator of FIG. 100 g of short fibers are pre-defibrated by a cotton sacking machine, and then introduced into the stirring tank 1 by an air flow from the sample feeding blower 3, and an air flow of 20 m / second is blown from the stirring blower 2 to the inside of the stirring tank 1. For 1 minute. 0.1 g of the fiber after stirring was collected from the sampling port 5 and spread on black paper, and the presence or absence of an independent fiber mass was visually evaluated.
○: Fiber mass is not generated
(Triangle | delta): The fiber lump has produced | generated a little x: The fiber lump has produced | generated abundantly (k) Evaluation of a nonwoven fabric Web shrinkage rate A sample of area A0 (vertical 20 cm × width 20 cm = 400 cm ² ) was cut from the web obtained when obtaining a dry or wet nonwoven fabric, and when the melting point of polyester A was Tm, this sample was (Tm + 10) It is allowed to stand for 15 minutes in a hot air dryer set at 0 ° C. (performs thermal bonding treatment), and thereafter the area of the nonwoven fabric (after thermal adhesion treatment) is A1, and is calculated by the following formula. The web shrinkage is 12% or less, and preferably 10% or less.
Web shrinkage (%) = {(A0−A1) / A0} × 100
2. Formation (uniformity)
The formation of the surface of the obtained nonwoven fabric was judged visually, and evaluated in two stages, with good ones as ◯ and bad ones as x.
3. Flexibility The obtained non-woven fabric was cut into 20 cm × 20 cm to make a sample, and the following three stages were evaluated from those having excellent flexibility due to the touch of a panel.
○: Excellent flexibility △: Slightly poor flexibility ×: Poor flexibility Bulkiness The obtained nonwoven fabric was cut out into 20 cm x 20 cm, and it was set as the sample, and it evaluated in the following three steps from the thing excellent in bulkiness by the touch and visual observation by a panelist.
○: Excellent in bulkiness △: Slightly poor in bulkiness ×: Poor in bulkiness

In Examples and Comparative Examples, as polyester B, a polyester having the following polymer composition, melting point or flow start temperature was used.
B-1: TPA / ε-caprolactone / EG / BD = 85/15/45/55 (molar ratio), melting point 160 ° C., intrinsic viscosity 0.72
B-2: TPA / EG / BD = 100/50/50 (molar ratio), melting point 180 ° C., intrinsic viscosity 0.78
B-3: TPA / EG / BD = 100/20/80 (molar ratio), melting point 195 ° C., intrinsic viscosity 0.62
B-4: TPA / IPA / EG = 72/28/100 (molar ratio), flow initiation temperature 152 ° C., intrinsic viscosity 0.80
B-5: TPA / IPA / EG = 70/30/100 (molar ratio), flow start temperature 140 ° C., intrinsic viscosity 0.79
B-6: TPA / EG = 100/100 (molar ratio), melting point 256 ° C., intrinsic viscosity 0.68
B-7: TPA / IPA / EG = 92/8/100 (molar ratio), melting point 235 ° C., intrinsic viscosity 0.65
B-8: TPA / BD = 100/100 (molar ratio), melting point 225 ° C., intrinsic viscosity 0.85
B-9: TPA / EG / BD = 100/83/17 (molar ratio), melting point 205 ° C., intrinsic viscosity 0.62
B-10: TPA / IPA / EG = 58/42/100 (molar ratio), flow initiation temperature 90 ° C., intrinsic viscosity 0.77

Example 1
The slurry of TPA and EG is continuously supplied to the esterification reactor and reacted under the conditions of a temperature of 250 ° C. and a pressure of 0.2 MPa, and a residence time of 8 hours is obtained to obtain a reaction product with an esterification reaction rate of 95%. It was. This reaction product was transferred to a polycondensation reaction vessel, HD was charged into the polycondensation reaction vessel, and stirred at a temperature of 240 ° C. and normal pressure for 1 hour. Next, EG slurry containing talc having an average particle size of 1.0 μm and a specific surface area of 35 m ² / g as a crystal nucleating agent was put into a polycondensation reaction can, and then the pressure in the reactor was gradually reduced while stirring. The polycondensation reaction was carried out for about 3 hours, and was discharged into a strand form by a conventional method to form chips. The obtained polyester A consists of TPA as an acidic component, 15 mol% of EG as a glycol component, and 85 mol% of HD, contains 0.5% by mass of talc as a crystal nucleating agent, has an intrinsic viscosity of 0.95, a melting point of 128 ° C., b / a was 0.06.
B-1 polymer is used as polyester B, and polyester A chip and polyester B-1 chip are supplied to the composite spinning apparatus so that polyester A has a sheath and polyester B has a core-sheath shape. Melt spinning was carried out at a mass ratio of the components of 50/50. At this time, spinning was performed under the conditions of a spinning temperature of 220 ° C., a discharge rate of 600 g / min, a spinning hole number of 1014, and a spinning speed of 800 m / min. Next, the spun yarn was cooled with cold air at 18 ° C. and taken out to obtain an undrawn yarn.
This undrawn yarn is bundled to a 110,000 dtex tow-like undrawn fiber, drawn at a draw ratio of 3.2 times and a draw temperature of 40 ° C., and then heat-treated with a heat drum (temperature of 110 ° C.). gave. Next, crimping was applied with a push-in crimper, and the fiber length was cut to 51 mm to obtain a polyester composite short fiber having a single yarn fineness of 2.2 decitex.
The obtained polyester composite short fiber is used as a binder fiber, and the main fiber is made of PET having a melting point of 256 ° C., a fineness of 2.2 dtex, a fiber length of 51 mm, a strength of 5.5 cN / dtex, an elongation of 40%, 170 ° C., 15 minutes. Using a short fiber having a dry heat shrinkage of 3.0%, a dry web was prepared through a card machine with a mixing ratio of 20/80 (binder fiber / main fiber). The obtained dry web was heat treated for 1 minute with a continuous heat treatment machine at a temperature of 138 ° C. and an air volume of 20 m ³ / min to obtain a dry nonwoven fabric with a basis weight of 100 g / m ² .

Examples 2-3 and Comparative Examples 1-2
A polyester composite short fiber was obtained in the same manner as in Example 1 except that the amount of talc added as the crystal nucleating agent was changed to the content in polyester A shown in Table 1. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Examples 4-7, Comparative Example 3
A polyester composite short fiber was obtained in the same manner as in Example 1 except that the polymer shown in Table 1 was used as the polyester B. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Example 8
TPA, HD, and BD are supplied to the esterification reactor, talc having an average particle size of 1.0 μm and a specific surface area of 35 m ² / g is added as a crystal nucleating agent, and the conditions are 3 at a temperature of 230 ° C. and a pressure of 0.2 MPa. After stirring for a period of time and carrying out an esterification reaction, it was transferred to a polycondensation reaction can. Then, the pressure in the reactor was gradually reduced, and the polycondensation reaction was carried out for about 3 hours with stirring, and the strand was discharged into a strand by a conventional method to form chips. The obtained polyester A comprises TPA as an acidic component, 20 mol% of 1,4-butanediol (BD) as a glycol component, and 80 mol% of HD, contains 0.5% by mass of talc as a crystal nucleating agent, and has an intrinsic viscosity of 0 .98, melting point 130 ° C.
A polyester composite short fiber was obtained in the same manner as in Example 1 except that a polymer of B-1 was used as polyester B, and a polyester A chip and a polyester B-1 chip were used. And the dry type nonwoven fabric was obtained like Example 1 using the obtained polyester composite short fiber.

Examples 9-10, Comparative Examples 4-5
A polyester composite short fiber was obtained in the same manner as in Example 8, except that the amount of talc added as the crystal nucleating agent was changed to the content in polyester A shown in Table 1. Further, a dry nonwoven fabric was obtained in the same manner as in Example 8.

Examples 11-14, Comparative Example 6
A polyester composite short fiber was obtained in the same manner as in Example 8 except that the polymer shown in Table 1 was used as the polyester B. Further, a dry nonwoven fabric was obtained in the same manner as in Example 8.

Example 15
Using the polyester A used in Example 1, using a polymer B-6 as the polyester B, supplying the polyester A chip and the polyester B chip to the composite spinning apparatus, the polyester A becomes the sheath and the polyester B becomes the core. Thus, melt spinning was carried out at a mass ratio of both components of 50/50. At this time, spinning was performed under the conditions of a spinning temperature of 275 ° C., a single hole discharge rate of 0.393 g / min, and a spinning speed of 750 m / min. Next, the spun yarn was cooled with cold air at 12 ° C. and a humidity of 75% and taken out to obtain an undrawn yarn.
This unstretched yarn is converged to a 110,000 dtex tow-shaped unstretched fiber and stretched at a stretching ratio of 2.61 times and a stretching temperature of 60 ° C., and then heat-treated with a heat drum (temperature of 110 ° C.). gave. Next, mechanical crimping was applied with a push-in crimper, and the fiber length was cut to 51 mm to obtain a polyester composite short fiber having a single yarn fineness of 2.2 dtex.
And the dry type nonwoven fabric was obtained like Example 1 using the obtained polyester composite short fiber.

Example 16
A polyester composite short fiber was obtained in the same manner as in Example 15 except that the polymer of B-7 was used as polyester B and the spinning temperature was 255 ° C. Further, a dry nonwoven fabric was obtained in the same manner as in Example 15.

Example 17
A polyester composite short fiber was obtained in the same manner as in Example 15 except that B-8 polymer was used as polyester B and the spinning temperature was 245 ° C. Further, a dry nonwoven fabric was obtained in the same manner as in Example 15.

Example 18
A polyester composite short fiber was obtained in the same manner as in Example 15 except that a polymer of B-9 was used as polyester B and the spinning temperature was 235 ° C. Further, a dry nonwoven fabric was obtained in the same manner as in Example 15.

  Table 1 shows the characteristic values and evaluation results of the polyester composite short fibers and dry nonwoven fabrics obtained in Examples 1 to 18 and Comparative Examples 1 to 6.

As is clear from Table 1, the polyester composite short fibers of Examples 1 to 18 are those in which polyester A satisfies the formula (1), has high crystallinity, can be obtained with good spinning operability, and is stretched. The heat treatment could be performed satisfactorily and a product having a low dry heat shrinkage rate could be obtained. When a nonwoven fabric was obtained from these composite short fibers, a nonwoven fabric having a low web shrinkage and good dimensional stability and good formation could be obtained.
On the other hand, the polyester composite short fibers of Comparative Examples 1 and 4 have a low crystallization rate because the content of the crystal nucleating agent in the polyester A is too small, and the polyester composite short fibers of Comparative Examples 3 and 6 are polyesters. Since B had a flow start temperature of 90 ° C., none of the heat drum temperatures could be heat treated at the same temperature as in Examples 1 and 8, and the heat drum temperature was 80 ° C., so the resulting fiber was dry heat The shrinkage rate was large. For this reason, the web shrinkage rate at the time of obtaining a nonwoven fabric was large, and the obtained nonwoven fabric was poor in texture. Since the polyester composite short fibers of Comparative Examples 2 and 5 contained a large amount of the crystal nucleating agent in the polyester A, cut yarns were generated during spinning and the operability was poor. As a result, the variation in yarn quality increased, the dry heat shrinkage ratio increased, and the web shrinkage ratio increased when obtaining a nonwoven fabric, and the obtained nonwoven fabric was unsatisfactory.

Example 19
After the undrawn yarn was obtained in the same manner as in Example 1 and subjected to drawing and heat treatment, crimping was then applied by a push-in crimper with a nip pressure of 0.39 MPa and a staffin pressure of 0.07 MPa. Thereafter, an oil agent mainly composed of polyoxyethylene alkyl ether as a finishing oil agent was applied so as to have an adhesion amount of 0.2% by mass, and then cut to obtain a polyester composite short having a single yarn fineness of 2.2 dtex and a fiber length of 5 mm. Fiber was obtained. The crimped form of the obtained composite short fiber had an H / L of 0.16, a number of crimps of 5.5 pieces / 25 mm, and a crimp rate of 4.0%.

The obtained composite short fiber was used as a binder fiber, and a dry nonwoven fabric and a wet nonwoven fabric were prepared by the following method.
(Dry nonwoven fabric)
The short fiber shown in Reference Example 1 is used as the main fiber, and the mass ratio of the binder fiber to the main fiber (binder fiber / main fiber) is 50/50, using a simple airlaid tester shown in FIG. A dry nonwoven fabric of 50 g / m ² was obtained.
First, the main fibers and binder fibers input from the sample input blower 13 are rotated by the defibrating blade rotating motor 15 via the defibrating blade rotating sprocket 16, and each set is disassembled by a set of five first defibrating blades 11 and second defibrating blades 12. It was spun and scattered and dropped. Falling short fibers are sucked by the suction box 14 at the lower part and deposited on a cotton collecting conveyor 17 that moves in the direction of the arrow to create a web, which is then heat treated by a heat treatment machine 18 downstream (heat treatment temperature). : Melting point of polyester A + 10 ° C.) Almost all of polyester A was melted to form an adhesive component (polyester B was the main fiber), and the main fibers were bonded together to obtain a dry nonwoven fabric. The basis weight adjustment of the nonwoven fabric was performed by changing the moving speed of the cotton collection conveyor 17.
[Wet non-woven fabric]
The staple fiber shown in Reference Example 1 was used as the main fiber, and the mass ratio of the binder fiber to the main fiber (binder fiber / main fiber) was 50/50, and it was put into a pulp disintegrator (manufactured by Kumagaya Riki Kogyo) at 3000 rpm. Stir for 1 minute. After that, the obtained sample was transferred to a paper machine (Kumagaya Riki Kogyo's square sheet machine), and after adding a dispersion oil mainly composed of an alkyl phosphate metal salt, stirring was performed with an accompanying stirring blade to make paper. A wet web was prepared. The paper-made 25 × 25 cm wet non-woven web is heat treated for 5 minutes using a box-type hot air dryer (heat treatment temperature: melting point of polyester A + 10 ° C.), and almost all of polyester A is melted as an adhesive component (polyester) B became main fibers), and the main fibers were bonded to each other to obtain a wet nonwoven fabric having a basis weight of 50 g / m ² .

Examples 20-22
Undrawn yarn was obtained in the same manner as in Examples 4 to 6, and crimped with a push-in crimper in the same manner as in Example 19 on the drawn and heat-treated composite short fiber to obtain a polyester composite short fiber. .
Using this composite short fiber as a binder fiber, dry and wet nonwoven fabrics were obtained in the same manner as in Example 19.

Examples 23-26
Undrawn yarn was obtained in the same manner as in Examples 15 to 18, and crimped with a push-in crimper in the same manner as in Example 19 on the drawn and heat-treated composite short fiber to obtain a polyester composite short fiber. .
Using this composite short fiber as a binder fiber, dry and wet nonwoven fabrics were obtained in the same manner as in Example 19.

Examples 27-30
In the same manner as in Examples 8 and 11 to 13, undrawn yarn was obtained, and crimped crimped crimper was applied to the composite short fibers subjected to drawing and heat treatment in the same manner as in Example 19 to obtain polyester composite short fibers. Obtained.
Using this composite short fiber as a binder fiber, dry and wet nonwoven fabrics were obtained in the same manner as in Example 19.

Comparative Examples 7-8
Undrawn yarn was obtained in the same manner as in Comparative Examples 3 and 6, and the composite short fiber subjected to drawing and heat treatment was crimped by a push-in crimper in the same manner as in Example 19 to obtain a polyester composite short fiber. .
Using this composite short fiber as a binder fiber, dry and wet nonwoven fabrics were obtained in the same manner as in Example 19.

Reference example 1
A round cross section with a hole number of 518, using a PET having a melting point of 256 ° C. and an intrinsic viscosity of 0.61, using a normal melt spinning apparatus at a spinning temperature of 285 ° C., a discharge rate of 344 g / min, and a spinning speed of 950 m / min. The undrawn yarn was obtained. The resulting undrawn yarn was focused on a 12.3 ktex tow, then drawn at a draw ratio of 3.18 times and a draw temperature of 70 ° C., and a crimping condition was applied by a push-in crimper with a nip pressure of 0.32 MPa and a staffin pressure. Crimping was given as 0.09 MPa. Thereafter, an oil agent mainly composed of polyoxyethylene alkyl ether as a finishing oil agent was applied so as to have an adhesion amount of 0.2% by mass, and then cut into short fibers having a single yarn fineness of 2.2 dtex and a fiber length of 5 mm. Obtained. The crimped form of the obtained short fibers had an H / L of 0.177, a number of crimps of 6.1 pieces / 25 mm, and a crimp rate of 4.8%.

  Table 2 shows the characteristic values of the short fibers obtained in Examples 19 to 30, Comparative Examples 7 to 8 and Reference Example 1, the crimped form, the characteristic values of the obtained dry nonwoven fabric and wet nonwoven fabric, and the evaluation results.

As is clear from Table 2, the polyester composite short fibers of Examples 19 to 30 can be obtained with good spinning operability because the polyester A satisfies the formula (1) and has excellent crystallinity. Further, stretching and heat treatment could be performed satisfactorily and the dry heat shrinkage rate could be reduced. And since these composite short fibers are those which have been crimped in a crimped form that satisfies the condition (2) and also satisfies the expressions (3) to (5), the generation of fiber mass does not occur. It was a thing. And the web shrinkage rate at the time of heat-processing a web was also small, and the dry type and wet nonwoven fabric were able to be obtained with sufficient dimensional stability. Furthermore, the obtained dry and wet nonwoven fabrics were excellent in formation, flexibility and bulkiness.
On the other hand, the polyester composite short fibers of Comparative Examples 7 and 8 were those having a flow start temperature of 90 ° C. as polyester B, and had a high dry heat shrinkage rate. The nonwoven fabric could not be obtained with high dimensional stability. The obtained dry and wet nonwoven fabrics were inferior in both formation and flexibility.

Examples 31-38
Other than changing the conditions (nip pressure, staffin pressure) for applying crimp with a push-in crimper as shown in Table 3 and having the crimped part shape, number of crimps, and crimp rate shown in Table 3 Were carried out in the same manner as in Example 19 to obtain polyester composite short fibers.
Using this composite short fiber as a binder fiber, dry and wet nonwoven fabrics were obtained in the same manner as in Example 19.

  Table 3 shows the characteristic values of the polyester composite short fibers obtained in Examples 31 to 38, the crimped form, the characteristic values of the obtained dry nonwoven fabric and wet nonwoven fabric, and the evaluation results.

  As is clear from Table 3, the polyester composite short fibers of Examples 31 to 38 are obtained by changing the crimped form of the composite short fibers of Example 19, satisfying the condition (2), and (3) to (5) Since it was a thing of the crimped form which also satisfy | fills Formula, there was no production | generation of a fiber lump, and the obtained dry type nonwoven fabric and wet nonwoven fabric were excellent in formation, a softness | flexibility, and bulkiness.

It is an example of the DSC curve which shows the temperature-fall crystallization calculated | required from DSC of the polyester A which comprises the polyester composite short fiber of this invention. It is expansion explanatory drawing which shows an example of the crimped form of the polyester composite short fiber of this invention. It is explanatory drawing which shows the simple airflow stirring test machine for evaluating the production | generation of the fiber lump in an Example. It is explanatory drawing which shows the simple airlaid tester which manufactured the dry-type nonwoven fabric in the Example.

Claims (3)

It consists of a dicarboxylic acid component mainly composed of terephthalic acid and a diol component of 1,6-hexanediol of 50 mol% or more, contains 0.01 to 5.0% by mass of a crystal nucleating agent, and has a melting point of 100 to 150. DSC curve showing the temperature-falling crystallization obtained from the DSC with DSC satisfying the following formula (1), and the polyester B having a melting point or flow start temperature of 130 ° C or higher and higher than the melting point of the polyester A A polyester composite short, characterized in that the composite fiber is configured so that polyester A is arranged so as to occupy at least a part of the fiber surface in the cross-sectional shape of a single yarn, and the fiber length is 1.0 to 100 mm. fiber.
Formula (1) ... b / a ≧ 0.05 (mW / mg · ° C.)
Note that a is the temperature A1 (° C.) of the intersection between the tangent line and the baseline having the maximum inclination in the DSC curve indicating the temperature-falling crystallization, and the temperature A2 (° C.) of the intersection of the tangent line and the baseline having the minimum inclination. B) is the difference (B1-B2) between the baseline heat quantity B1 (mW) and the peak top heat quantity B2 (mW) at the peak top temperature (mg) The value divided by. The polyester composite short fiber according to claim 1, wherein crimps satisfying the following condition (2) are imparted, the fiber length is 1.0 to 30 mm, and the single yarn fineness is 0.3 to 20 dtex.
Condition (2): A triangle in which the crimped form imparted to the single yarn constituting the short fiber connects the bottom points of the valleys adjacent to the apex of the peaks at the maximum peak of the crimps The ratio (H / L) of the height (H) to the base length (L) satisfies the following formula (3).
0.01T + 0.10 ≦ H / L ≦ 0.02T + 0.25 (3)
T is the number of decitex (dtex) of single yarn fineness 3. The polyester composite short fiber according to claim 1, wherein a dry heat shrinkage rate at (Tm−30) ° C. is 7% or less when the melting point of the polyester A constituting the polyester composite short fiber is Tm.