JP2009280948A - Polyester conjugate short fiber and short fiber nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester conjugate short fiber capable of processing at a low temperature in thermobonding, particularly when used as a binder fiber, and excellent in heat adhesiveness, and a short fiber nonwoven fabric capable of being processed at a low temperature in thermobonding by putting the same between fiber structures and the like, having a small rate of heat shrinkage in thermobonding treatment, capable of bonding fiber structures and the like with good dimensional stability and excellent in adhesiveness. <P>SOLUTION: The polyester conjugate short fiber consists of a dicarboxylic acid component comprising terephthalic acid as the main component and a diol component comprising ≥50 mole% 1,6-hexanediol, contains 0.01-5.0 mass% crystal nucleus agent, and is composed of a polyester A having 100-150°C melting point (TmA) and a polylactic acid-based polymer having (TmA-30°C) to (TmA+30°C) melting point. In the polyester conjugate short fiber, the polyester A is arranged to occupy at least a part of the fiber surface in the cross sectional shape of a single yarn, and the fiber length is 1-100 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a composite short fiber composed of polyester and polylactic acid having a low melting point and excellent crystallinity, which is suitable for heat bonding, can be heat bonded at a low temperature, The present invention relates to a polyester composite staple fiber having a small shrinkage during the adhesion treatment and excellent in thermal adhesiveness, and a staple fiber nonwoven fabric composed of the staple 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.

  In recent years, non-woven structures formed by bonding fibers have been proposed in automobile interior materials, and non-woven structures may be bonded together for the purpose of reinforcing them. Thus, when non-woven structures are bonded to each other, both non-woven structures are formed by interposing a non-woven structure composed of fibers having thermal adhesiveness between the non-woven structure and the non-woven structure, and applying heat treatment. Glue things. As such a nonwoven fabric, many nonwoven fabrics are mainly composed of polyester fibers, and therefore, those composed of polyester polymers are preferable from the viewpoint of recycling.

  And as such a nonwoven fabric, the nonwoven fabric which consists of a core-sheath-type composite fiber which made the polyethylene terephthalate the core part and made the polyethylene terephthalate type copolymer copolymerized with the isophthalic acid component into the sheath part is used. This non-woven fabric consists of a core portion having a high melting point and a sheath portion having a low melting point, and in the case of heat bonding treatment, the fiber form is maintained without melting the core portion, and only the sheath portion is melted. It is an adhesive component.

  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. For this reason, there has been a problem that the fibers shrink during the thermal bonding treatment and the dimensional stability of the obtained nonwoven structure deteriorates. In addition, when the bonded non-woven structure is used in a high temperature atmosphere, there is a problem that the bonding strength is reduced and deformed.

  As a solution to the above problem, Patent Document 1 describes 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, since the copolymer of the sheath part is crystalline and has a clear melting point, the nonwoven fabric using this composite fiber has a small shrinkage during the thermal bonding treatment. For this reason, the dimensional stability of the bonded nonwoven structure or the like is excellent, and the heat resistance when the bonded nonwoven structure is used in a high-temperature atmosphere is also excellent.

  However, the copolyester of the sheath part has a melting point in the range of 150 to 200 ° C. and is not yet a low melting point region, and it is necessary to increase the processing temperature during the thermal bonding process, and the cost It was also disadvantageous.

JP 2001-3256 A

  The present invention solves the above-mentioned problems, and is obtained by using a polyester having a low melting point and excellent crystallinity, and performing melt spinning, stretching, and heat treatment with good operability in a normal production apparatus. In particular, when used as a binder fiber, it is a technical problem to provide a polyester composite short fiber that can be processed at a low temperature when thermally bonded, and that is excellent in thermal adhesiveness. . Furthermore, it can be processed at a low temperature when it is bonded to a fiber structure or the like, and the heat shrinkage rate during the heat bonding process is small, and the fiber structure or the like is bonded with good dimensional stability. It is a technical problem to provide a short fiber nonwoven fabric that can be manufactured and has excellent adhesion.

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 gist of the present invention is the following (a) and (b).
(A) 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 ( TmA) is a composite fiber composed of a polyester A having a temperature of 100 to 150 ° C. and a polylactic acid polymer having a melting point of (TmA-30 ° C.) to (TmA + 30 ° C.). A polyester composite short fiber, wherein A is arranged so as to occupy at least a part of the fiber surface, and the fiber length is 1 to 100 mm.
(A) A short fiber nonwoven fabric comprising a web containing only the polyester composite short fiber described in (a), wherein at least a part of the polyester composite short fiber is melted to form an adhesive portion.

The polyester composite short fiber of the present invention has a low melting point but has excellent crystallinity disposed on at least a part of the fiber surface, so that there is no welding between single yarns in the spinning process, and in the drawing and heat treatment processes. Can be heat-treated at a high temperature, and can be a short fiber having a low dry heat shrinkage rate. Furthermore, by using a polylactic acid-based polymer as the other component, when both components are melted by the thermal bonding treatment, an adhesive component having excellent adhesiveness is obtained.
For this reason, the processed yarn or nonwoven fabric using the polyester composite short fiber of the present invention can be heat-bonded at a low temperature, has a small shrinkage during the heat-bonding process, has excellent bonding performance, It is suitable for use as a hot melt sheet.
The short fiber nonwoven fabric of the present invention is suitable as a hot melt sheet for use in thermal bonding treatment by interposing it in a fiber structure, etc., and can be bonded by low-temperature thermal bonding treatment, and can be adhesive. It is possible to obtain a fiber structure or the like (product) that is excellent and has a strong dimensional stability and is firmly bonded.
In addition, the polyester composite short fiber of the present invention is one in which a polyester having excellent crystallinity is arranged on at least a part of the fiber surface, so that it is easy to impart crimp and imparts a specific shape of crimp. It can be. By using short fibers having such crimps, fiber masses are formed in web forming processes such as air flow, feeding of short fibers by a carding machine, dispersion, defibration, laminating processes, etc. in the nonwoven fabric manufacturing process. Thus, a short fiber nonwoven fabric having excellent uniformity, high quality and excellent bulkiness can be obtained. 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. It is possible to obtain an excellent airlaid nonwoven fabric.

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 in the short fiber nonwoven fabric of this invention. It is expansion explanatory drawing which shows 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.

  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 a polylactic acid polymer, and is arranged so 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 shapes include side-by-side types, concentric core-sheath types, eccentric core-sheath types, multilayer types, and the like. Among them, polyester A is a sheath part in a cross-sectional shape of a single yarn, and a polylactic acid polymer is used. It is preferable that it is a core-sheath shape arranged in the core part.
And as a core-sheath shape, you may have one core part, or you may have multiple. When it has a some core part, it is preferable that the number of core parts shall be 2-10.

  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 (TmA) of 100 to 150 ° C, preferably 110 to 140 ° C. When TmA is less than 100 ° C., the thermal stability (heat resistance) when used in a high temperature atmosphere is inferior. On the other hand, when it exceeds 150 ° C., it is necessary to increase the heat bonding processing temperature at the time of the heat bonding treatment, which is inferior in workability and economy. Further, it is not preferable because the quality and texture of the product obtained by the thermal bonding 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. It is preferable to satisfy the formula (1). And, when fiberizing using polyester A and a polylactic acid-based polymer, since it becomes possible to heat-treat at a high temperature in the drawing and heat treatment process without causing welding between single yarns in the melt spinning process, The fiber can have a low dry heat shrinkage.

  When the content of the crystal nucleating agent is less than 0.01% by mass, the crystallization rate at the time of temperature reduction cannot be improved. 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.

  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. In the case where 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.

Furthermore, polyester A preferably has a DSC curve showing temperature-fall crystallization determined from DSC satisfying the following formula (1), and it is particularly preferable that b / a ≧ 0.06. On the other hand, the larger b / a, the better the crystallinity when the temperature is lowered. However, in order to achieve the target effect of the present invention, b / a is preferably 2.0 or less.
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 rate of temperature rise (fall) of 20 ° C./min and a sample amount of 2 mg. At this time, a sample obtained by eluting a polylactic acid polymer from a polyester composite short fiber is used. For example, dioxane is put into an ultrasonic cleaner, and the polyester composite short fiber is immersed in dioxane and ultrasonic cleaning is performed for 2 hours. The short fiber after washing is taken out and dried at 100 ° C. for 2 hours, and 2 mg is collected as a sample.

  b / a is obtained from the DSC curve measured as described above. 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 becomes possible.

  Next, the polylactic acid polymer will be described. Polylactic acid-based polymers include poly-D-lactic acid, poly-L-lactic acid, poly-DL-lactic acid, which is a copolymer of poly-D-lactic acid and poly-L-lactic acid, and poly-D-lactic acid and poly-L-lactic acid. Mixture (stereo complex), copolymer of poly D-lactic acid and hydroxycarboxylic acid, copolymer of poly L-lactic acid and hydroxycarboxylic acid, poly D-lactic acid or poly L-lactic acid and aliphatic dicarboxylic acid and fat A copolymer with a group diol or a blend thereof can be used.

The range of the melting point of the polylactic acid-based polymer is from 30 ° C. lower than the melting point (TmA) of the polyester A to 30 ° C. higher than the melting point (TmA) of the polyester A. That is, (TmA-30 ° C) to (TmA + 30 ° C), and (TmA-30 ° C) to (TmA + 10 ° C) is preferable.
As described above, when L-lactic acid or D-lactic acid is used alone, the melting point is about 180 ° C., but in the case of a copolymer of D-lactic acid and L-lactic acid, the ratio of either component is 10 mol. When it is about%, the melting point is about 130 ° C.

  Therefore, as polylactic acid, L / D or D / which is the content ratio (molar ratio) of L-lactic acid and D-lactic acid indicated by the content ratio of L-lactic acid or D-lactic acid when polymerizing using lactide as a raw material. L is preferably about 85/15 to 92/8.

  The polyester composite short fiber of the present invention is preferably used as a binder fiber composed of polyester A and a polylactic acid-based polymer, and the polyester A and the polylactic acid-based polymer are melted together with an adhesive component by thermal bonding treatment. It is preferable to do.

  When the polyester A having a polymer composition as described above and a polylactic acid polymer are melted and mixed, the action is not clear, but the adhesive component has excellent adhesive performance. Therefore, a product (processed yarn, non-woven fabric, etc.) using the polyester composite short fiber of the present invention as a binder fiber has good adhesion between main fibers and can have high adhesive strength.

  When the melting point of the polylactic acid polymer is less than (TmA-30 ° C.), it becomes difficult to melt-spin it as a composite fiber together with polyester A, and it becomes difficult to obtain the fiber. On the other hand, when the melting point of the polylactic acid polymer exceeds (TmA + 30 ° C.), it becomes difficult to melt the polylactic acid polymer by the low temperature thermal bonding treatment for melting the polyester A, and the binder fiber having high adhesive strength. Therefore, in order to melt the polylactic acid polymer, it is necessary to increase the thermal bonding temperature, which is disadvantageous in terms of cost.

  In addition, the polylactic acid-based polymer in the present invention includes cyclic lactones such as ε-caprolactone, α-oxybutyric acid such as α-hydroxybutyric acid, α-hydroxyisobutyric acid, α-hydroxyvaleric acid and the like as long as the purpose is not impaired. Acids, glycols such as ethylene glycol and 1,4-butanediol, and dicarboxylic acids such as succinic acid and sebacic acid may be contained.

  In order to perform melt spinning with good operability, the composite ratio (mass ratio) of the polyester A of the polyester composite short fiber of the present invention and the polylactic acid polymer is preferably 20/80 to 80/20, especially 30 / 70 to 70/30 is preferable.

  And since the polyester composite short fiber of the present invention is arranged on at least a part of the fiber surface as described above, the polyester A excellent in crystallinity does not cause welding between single yarns when melt spinning, Drawing and heat treatment can be performed at a high temperature, and a fiber having a low thermal shrinkage can be obtained. Specifically, the polyester composite short fiber of the present invention preferably has a dry heat shrinkage of 7% or less at (TmA-30) ° C. when the melting point of polyester A is TmA, and more preferably 5% or less. It is preferable that it is 4.5% to 0.5%.

  The dry heat shrinkage of the polyester composite short fiber of the present invention is measured by the dry heat shrinkage measurement method in the measurement of shrinkage according to JIS L-1015. The measurement is performed by measuring the processing temperature as (TmA-30) ° C. In addition, when the fiber length is short and measurement is difficult, it shall measure using the fiber before cutting into a short fiber.

  In the polyester composite short fiber of the present invention, as described above, the polyester A having excellent crystallinity is disposed on at least a part of the fiber surface. Heat treatment can be performed at a high temperature, and a fiber having a low heat shrinkage rate can be obtained. Thus, as will be described later, the thermal shrinkage rate (area shrinkage rate) of the short fiber nonwoven fabric of the present invention can be lowered.

  Furthermore, since the polyester composite short fiber of the present invention has a low melting point and high crystallinity polyester A is arranged on at least a part of the fiber surface, it can impart crimps having a specific shape. It is. And the polyester composite short fiber of this invention becomes a suitable fiber for obtaining an airlaid nonwoven fabric especially by providing the crimp of the specific shape mentioned later. The crimp having such a shape is preferably provided with mechanical crimp by a stuffing box method, an indentation heating gear method, or the like.

In the polyester composite short fiber of the present invention, the crimped form imparted to the single yarn constituting the short fiber has two bottom points of the valley adjacent to the peak of the peak at the maximum peak of the crimp. It is preferable that the ratio (H / L) of the height (H) of the connected triangles and the length (L) of the base side satisfies the following formula (3).
(3) Formula: 0.01T + 0.10 ≦ H / L ≦ 0.02T + 0.25
T is the number of decitex (dtex) of single yarn fineness

  By having such a crimped form, the fiber mass is not generated in the web forming process such as air flow, feeding of short fibers by a card machine, dispersion, defibration, laminating process, etc. It is possible to obtain a short fiber nonwoven fabric that is excellent in properties, high quality, and excellent in bulkiness.

  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), static electricity due to friction between the fibers and between the fibers and the metal is less likely to occur. In addition, since the generated static electricity is difficult to accumulate, the short fibers gather to form a fiber lump, which is significantly reduced.

  The crimp form of the single yarn of the composite short fiber in 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 composite short fiber in 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, a part of the short fiber nonwoven fabric is cut out, and 20 single fibers are arbitrarily taken out from the unbonded part. 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.

Further, the composite short fiber according to 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)]. preferable.
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 composite short fiber according to the present invention satisfies 0.8T + 0.3 ≦ crimp rate ≦ 1.0T + 4.9 (5) (where T is the number of dtex of the single yarn fineness). preferable.
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 producing a nonwoven fabric 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.

  In addition, even in a wet nonwoven fabric, it is possible to prevent the generation of fiber lumps due to the friction between fibers and fibers and between the machines, and the single fibers have good dispersion, and the contact points (surfaces) between the single fibers. Since the fibers are less likely to converge, the wet nonwoven fabric having excellent uniformity and sufficient bulkiness can be obtained.

  In addition, the polyester composite short fiber of the present invention has a fiber length of 1 to 100 mm, but when the short fiber having a crimped shape as described above is used, the fiber length is 1 to 30 mm. 20 mm is preferable.

  If the fiber length is less than 1 mm, the fibers are welded or glued by heat during cutting. On the other hand, when it exceeds 30 mm, in a dry nonwoven fabric, in the manufacturing process by the airlaid method, fiber lumps are likely to be generated in the process of defibration with an air flow and lamination to obtain a web. In addition, in wet nonwoven fabrics, fiber lumps are likely to occur when a web is obtained on a paper machine, and the resulting nonwoven fabric is inferior in uniformity.

  Furthermore, the polyester composite short fiber of the present invention preferably has a single yarn fineness of 0.3 to 20 dtex, more preferably 0.5 to 15 dtex, and even more preferably 1.0 to 10 dtex. When the single yarn fineness is less than 0.3 dtex, the single yarn is frequently cut in the spinning and drawing processes, the operability is deteriorated, and the quality of the resulting nonwoven fabric tends to be lowered. On the other hand, when the single yarn fineness exceeds 20 dtex, cooling of the spun yarn becomes insufficient, the fiber quality is lowered, and the quality of the resulting nonwoven fabric tends to be lowered.

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

  Next, the short fiber nonwoven fabric of this invention consists of a web containing only the above-mentioned polyester composite short fiber, and at least a part of the polyester composite short fiber melts to form an adhesive part.

  That is, the short fiber nonwoven fabric of the present invention uses only a polyester composite short fiber composed of polyester A and a polylactic acid-based polymer (content rate: 100%), and creates a web containing only the polyester composite short fiber. And in order to hold | maintain the form as a nonwoven fabric, at least one part of a polyester composite short fiber is fuse | melted, and short fibers are adhere | attached.

  In the short fiber nonwoven fabric of the present invention, the adhesive portion is formed by melting only a part of the polyester A, formed by melting all of the polyester A, one of the polylactic acid polymer in addition to the polyester A Although the part may also be formed by melting, it is preferable that only a part of the polyester A is melted to form an adhesive part. And as a form of such a nonwoven fabric, it is preferable that the polyester composite short fiber is a thing by partial thermocompression bonding.

  The short fiber nonwoven fabric of the present invention may be either a dry short fiber nonwoven fabric or a wet short fiber nonwoven fabric.

  The short fiber nonwoven fabric of the present invention has an area shrinkage of 10% or less in an atmosphere at a temperature (TmA-30 ° C.) 30 ° C. lower than the melting point (TmA) of the polyester A of the polyester composite short fiber. It is preferably 0% or less, and more preferably 6.5% or less.

The area shrinkage rate is obtained as follows. Cut the short fiber nonwoven fabric into an area A0 (20 cm × 20 cm = 400 cm ² ) as a sample and leave it in a hot air drier maintained at (TmA-30) ° C. for 15 minutes. The area of the nonwoven fabric is defined as A1, and the area shrinkage rate is obtained by the following formula.
Area shrinkage (%) = {(A0−A1) / A0} × 100

  When the area shrinkage of the short fiber nonwoven fabric is 10% or less, the shrinkage at the time of heat bonding treatment is small, the shrinkage at the time of interposing between non-woven structures and the like is small, and the resulting product (non- Woven structures and the like) have excellent dimensional stability. When the area shrinkage rate exceeds 10%, the heat shrinkage rate increases, and the product obtained by thermal bonding using the short fiber nonwoven fabric of the present invention cannot be bonded well due to shrinkage. Will be inferior.

Although the fabric weight of the short fiber nonwoven fabric of this invention is not specifically limited, It is preferable that it is 10-300 g / m < ² >. If the basis weight is less than 10 g / m ² , the formation and mechanical strength are inferior, and it tends to be unusable for practical use. On the other hand, when the basis weight exceeds 300 g / m ² , it is disadvantageous in terms of cost.

  Next, the manufacturing method of the polyester composite short fiber of this invention is demonstrated using an example. First, the dicarboxylic acid component and the diol component are esterified or transesterified, and a polynuclear reaction is performed by adding a crystal nucleating agent. When the polyester reaches a predetermined intrinsic viscosity in the polycondensation reaction, it is discharged into a strand, cooled, and cut into chips. Next, this chip (polyester A) and a polylactic acid polymer chip 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 into a yarn bundle, and stretched at a stretch ratio of about 2 to 4 times between rollers. Subsequently, heat treatment is performed at 100 to 120 ° C., and after applying a finishing oil, mechanical crimping is applied with a stuffing box or the like, and the polyester fiber is cut into a target fiber length to obtain a polyester composite short fiber.

In order to make the polyester composite short fiber to be provided with mechanical crimping that satisfies the condition (2), the stretching condition (magnification, temperature) and the crimping condition (nip) in a crimping apparatus such as an indentation type crimper (Pressure, staffin pressure) can be appropriately changed.
In addition, when obtaining a wet nonwoven fabric, it is preferable to use the composite short fiber which is not provided with crimp without giving mechanical crimp.

The manufacturing method of the short fiber nonwoven fabric (dry type) of this invention is demonstrated using an example.
Using only the polyester composite short fiber (having mechanical crimps) obtained as described above, a dry web is prepared by defibration with a card machine. A part of the composite short fibers of the obtained web is melted and thermally bonded to obtain a dry short fiber nonwoven fabric.

  At this time, as a method of thermally bonding at least a part of the polyester composite short fibers constituting the web, a hot press method using a hot embossing device or an ultrasonic welding device, a hot air circulation method using dry heat such as a hot air dryer, etc. A wet heat system using heating steam, a system using an ultrasonic welding apparatus, or the like can be used.

  As described above, the short fiber nonwoven fabric of the present invention is preferably one in which the polyester composite short fibers constituting the nonwoven fabric are partially thermocompression-bonded. A pattern using a partial thermocompression bonding apparatus composed of an embossing roll or an embossing roll and a flat roll, an ultrasonic oscillator that oscillates an ultrasonic wave of about 20 kHz, and a pattern having convex protrusions in the form of dots or bands on the circumference A method using an apparatus composed of a roll is exemplified.

  In the case of using a pair of embossing rolls or a partial thermocompression bonding apparatus composed of an embossing roll and a flat roll, the short fiber fusion is performed by melting or softening the polyester A of the composite short fiber present at the portion contacting the convex part of the embossing roll. An area is formed, and the composite short fibers are bonded to each other by the fused area.

  In addition, when using a device comprising an ultrasonic oscillator and a pattern roll having convex protrusions in the form of dots or strips on the circumference, a web is placed between the pattern roll and the support having the ultrasonic oscillator. Through, an ultrasonic wave of about 20 kHz is oscillated and point-bonded.

  In the short fiber nonwoven fabric of the present invention, the individual parts subjected to partial thermocompression bonding may have any shape such as a circle, an ellipse, a rhombus, a triangle, a T-shape, and a well.

Next, the manufacturing method of the short fiber nonwoven fabric (wet) of this invention is demonstrated using an example.
Using only the polyester composite short fibers (not mechanically crimped) obtained as described above, they are put into a pulp disintegrator, defibrated, and a wet web is prepared with a paper machine. Excess water is dehydrated from the wet web using a press machine, and then a portion of the polyester composite short fiber is melted and thermally bonded in the same manner as the dry nonwoven fabric to obtain a wet short fiber 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) Intrinsic viscosity of polyester A, relative viscosity of polylactic acid-based polymer Measured 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 equimolar mixture of phenol and ethane tetrachloride as a solvent. .
(B) Melting point of polyester A, DSC curve showing temperature drop crystallization determined from DSC Measured by the above method.
(C) Polymer composition of polyester A 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-400 NMR produced by JEOL Ltd. 1H-NMR was measured with an apparatus and determined from the integrated intensity of the proton peak of each copolymer component in the obtained chart.
(D) Content of L-lactic acid and D-lactic acid in polylactic acid-based polymer Measured by a high performance liquid chromatography method using an equal mass mixed solution of ultrapure water and a methanol solution of 1N sodium hydroxide as a solvent. Sumichiral OA6100 was used for the column, and it detected with the UV absorption measuring device.
(E) 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 time / ton, or welding occurs between single yarns.
(F) Dry heat shrinkage (%) of polyester composite short fiber
Measurement was performed by the method described above.
(G) Production of fiber mass The production of the fiber mass was evaluated for the obtained composite short fiber using the simple air flow stirring tester shown in 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 (h) Evaluation of a short fiber nonwoven fabric. Weighing 10 samples (length 10 cm x width 10 cm) from the obtained short fiber nonwoven fabric and reaching the equilibrium moisture, weighed the mass (g) of each sample piece, and measured the average value of the values It was set as the basis weight (g / m ² ) of the nonwoven fabric in terms of area.
2. Formation The formation of the surface of the obtained short fiber nonwoven fabric was evaluated by visual and tactile sensation in two stages (excellent one is ◯, two stages of ◯ and X).
3. 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 Δ: Slightly poor in bulkiness ×: Poor in bulkiness Area shrinkage rate Measured by the method described above.
5. Adhesive strength (N)
Polyethylene terephthalate fiber (fiber length 51 mm, fineness 2.2 T) and unite polyester-based core-sheath composite binder fiber <7080> (fiber length 51 mm, fineness 2.2 T) are blended in a mass ratio of 1: 1 to provide a card. A web having a basis weight of 400 g / m ² is prepared by a machine and subjected to a fusion treatment under a heat treatment condition of 180 ° C. × 60 seconds using a hot air dryer to obtain a short fiber nonwoven fabric.
Further, the thickness of the laminated nonwoven fabric is regulated so that the thickness of the laminated nonwoven fabric is 5 mm by sandwiching the nonwoven fabric of the short fibers obtained in Examples and Comparative Examples (hereinafter referred to as the short fiber nonwoven fabric M) between the two short fiber nonwoven fabrics. Then, using a hot air dryer, a heat treatment condition (melting point of polyester A of composite short fibers constituting short fiber nonwoven fabric M + 10) is performed at 100 ° C. for 100 seconds to form a laminate having a thickness of 5 mm. Five sample pieces having a sample length of 20 cm and a sample width of 5 cm were prepared from the laminate, 10 cm between the two pieces of the short fiber nonwoven fabric of the sample piece was peeled, and the peeled portion was gripped and stretched at an interval of 5 cm and a tensile speed of 10 cm / min. The peel strength (N / 5 cm) was measured. And the average value of 5 sample pieces was made into adhesive strength (N).
Here, the adhesive strength means that after the short fiber nonwoven fabric M is integrated with the polyester nonwoven structure, etc., the short fiber nonwoven fabric M is melted to integrate the polyester nonwoven structures together, and then the nonwoven structure It is a strong value required when peeling between objects. In the present invention, this adhesive strength is preferably 50 N or more. When the adhesive strength is less than 50N, the adhesive strength with the nonwoven structure is inferior, and the integrated structure is likely to peel off the nonwoven fabric structure while being used.

Example 1
Polyester A comprises TPA as an acidic component, EG 15 mol% and HD 85 mol% as a glycol component, 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., and a b / a of 0 .06 was used.
As a polylactic acid-based polymer, polylactic acid (polylactic acid) having a L / D ratio of 89.8 / 10.2, a melting point of 130 ° C., and a relative viscosity of 1.83, is L-lactic acid and D-lactic acid. a) was used.
The polyester A chip and the polylactic acid chip were supplied to the composite spinning apparatus, and the polyester A was the sheath part and the polylactic acid was the core part, and melt spinning was performed at a mass ratio of both components of 50/50. At this time, spinning was performed under the conditions of a spinning temperature of 220 ° C., a single hole discharge rate of 0.530 g / min, and a spinning speed of 750 m / min. Next, the spun yarn was cooled with cold air at 18 ° C. and taken out to obtain an undrawn yarn.
The unstretched fibers are gathered into 350,000 dtex tow-shaped unstretched fibers and stretched at a stretch ratio of 3.2 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.
The obtained polyester composite short fiber was defibrated through a card machine to obtain a dry nonwoven web of 50 g / m ² . Thereafter, this dry nonwoven web was passed through a partial thermocompression bonding apparatus composed of an embossing roll and a flat roll, and partially thermocompression bonded under the conditions of a roll temperature of 100 ° C. and a linear pressure of 500 N / cm. In this way, a dry short fiber nonwoven fabric with a basis weight of 50 g / m ² was obtained in which only a part of the composite short fibers was melted and the composite short fibers were partially thermocompression bonded (crimp area ratio 14.9%, crimp point density 21.9 pieces / cm ² ).

Example 2
As a polylactic acid polymer, polylactic acid (polylactic acid having a content ratio of L-lactic acid to D-lactic acid of 90.5 / 9.5, a melting point of 135 ° C., and a relative viscosity of 1.85) A polyester composite staple fiber was obtained in the same manner as in Example 1 except that b) was used. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Example 3
As a polylactic acid-based polymer, a polylactic acid (polylactic acid having a L / D content ratio of 85.9 / 14.1, a melting point of 110 ° C., and a relative viscosity of 1.88, which is a content ratio of L-lactic acid and D-lactic acid. A polyester composite staple fiber was obtained in the same manner as in Example 1 except that c) was used. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Example 4
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, has an intrinsic viscosity of 0.98, A polyester composite short fiber was obtained in the same manner as in Example 1 by using a polylactic acid a having a melting point of 130 ° C. and a b / a of 0.11 and using the polylactic acid a used in Example 1 as a polylactic acid polymer. Then, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Example 5
A polyester composite short fiber was obtained in the same manner as in Example 4 except that the polylactic acid b used in Example 2 was used as the polylactic acid polymer. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 4.

Example 6
A polyester composite short fiber was obtained in the same manner as in Example 4 except that the polylactic acid c used in Example 3 was used as the polylactic acid polymer. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 4.

Comparative Example 1
As a polylactic acid-based polymer, L / D, which is the content ratio of L-lactic acid and D-lactic acid, is 83.7 / 16.3, a melting point is 90 ° C., and a relative viscosity is 1.91. A polyester composite staple fiber was obtained in the same manner as in Example 1 except that d) was used. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Comparative Example 2
As a polylactic acid-based polymer, polylactic acid (polylactic acid having a content ratio of L-lactic acid to D-lactic acid of 98.8 / 1.2, a melting point of 170 ° C. and a relative viscosity of 1.88) A polyester composite staple fiber was obtained in the same manner as in Example 1 except that d) was used. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Comparative Example 3
Using only the polyester A used in Example 1, a polyester A chip was supplied to a spinning device, and spinning was performed under the conditions of a spinning temperature of 220 ° C., a discharge rate of 307 g / min, a spinning hole number of 518, and a spinning speed of 850 m / min. Next, the spun yarn was cooled with cold air at 18 ° C. 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 2.62 times and a stretching 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 polyester fiber was cut into a fiber length of 51 mm to obtain a polyester staple fiber having a single yarn fineness of 2.2 decitex. Furthermore, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1 by using the obtained polyester short fiber.

Comparative Example 4
Except that only the polyester A used in Example 4 was used, melt spinning and stretching were performed in the same manner as in Comparative Example 3 to obtain polyester short fibers. Furthermore, a dry short fiber nonwoven fabric was obtained in the same manner as in Comparative Example 3 using the obtained polyester short fibers.

  Table 1 shows the characteristic values of the polyester composite short fibers and polyester short fibers obtained in Examples 1 to 6 and Comparative Examples 1 to 4, the characteristic values of the obtained dry short fiber nonwoven fabric, and the evaluation results.

  As is clear from Table 1, in Examples 1 to 6, polyester composite short fibers could be obtained with good spinning and stretching operations, and the dry heat shrinkage of the composite short fibers was low. For this reason, the obtained dry short fiber nonwoven fabric has good formation, has a low area shrinkage, can be bonded with good dimensional stability, and is composed of other polyester fibers. The adhesive strength was excellent.

  On the other hand, in Comparative Example 1, since the melting point of the polylactic acid polymer was too low, it became difficult to melt-spin it as a composite fiber together with polyester A, and the spinning operability was poor. In Comparative Example 2, since the melting point of the polylactic acid polymer was too high, the composite short fiber could not melt the polylactic acid polymer by the thermal bonding treatment of the melting point of polyester A + 10 ° C., and the adhesive component was reduced. For this reason, the obtained dry short fiber nonwoven fabric had low adhesive strength. In Comparative Examples 3 and 4, since the short fibers comprising only polyester A were used as the short fibers constituting the nonwoven fabric, the synergistic effect of polyester A and the polylactic acid polymer was not obtained as an effect at the time of bonding, and the adhesive strength was high. It became low.

Example 7
Using polyester A and polylactic acid polymer similar to Example 1 and performing melt spinning, stretching and heat treatment in the same manner as in Example 1 and applying a finishing oil agent, no crimping is applied by an indentation type crimper. Then, a fiber length of 5 mm was cut to obtain a polyester composite short fiber having a single yarn fineness of 2.2 dtex.
The obtained polyester composite short fiber was put into a pulp disintegrator (manufactured by Kumagai Riki Kogyo) and stirred at 3000 rpm for 1 minute. Then, the obtained sample was made into the wet nonwoven fabric web with the paper machine (Kumagaya Riki Kogyo square sheet machine). Thereafter, the wet nonwoven web was partially thermocompression-bonded in the same manner as in Example 1, and only a part of the polyester A of the composite short fiber was melted, so that the composite short fiber was partially thermocompressed (compression area ratio 14. A wet short fiber nonwoven fabric having a density of 9% and a compression point density of 21.9 / cm ² ) per unit area of 50 g / m ² was obtained.

Example 8
A polyester composite short fiber was obtained in the same manner as in Example 7 except that the polylactic acid b used in Example 2 was used as the polylactic acid polymer. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 7.

Example 9
A polyester composite short fiber was obtained in the same manner as in Example 7 except that the polylactic acid c used in Example 3 was used as the polylactic acid polymer. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 7.

Example 10
Using the same polyester A and polylactic acid a as in Example 4 and performing melt spinning, stretching and heat treatment in the same manner as in Example 4 and applying a finishing oil agent, without applying mechanical crimping with a push-in crimper The fiber length was cut to 5 mm to obtain a polyester composite short fiber having a single yarn fineness of 2.2 dtex.
A wet short fiber nonwoven fabric was obtained in the same manner as in Example 7 using the obtained polyester composite short fiber.

Example 11
A polyester composite short fiber was obtained in the same manner as in Example 10 except that the polylactic acid b used in Example 2 was used as the polylactic acid polymer. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 10.

Example 12
A polyester composite short fiber was obtained in the same manner as in Example 10 except that the polylactic acid c used in Example 3 was used as the polylactic acid polymer. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 10.

Comparative Example 5
A polyester composite short fiber was obtained in the same manner as in Example 7 except that the polylactic acid d used in Comparative Example 1 was used as the polylactic acid polymer. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 7.

Comparative Example 6
A polyester composite short fiber was obtained in the same manner as in Example 7 except that the polylactic acid e used in Comparative Example 2 was used as the polylactic acid polymer. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 7.

Comparative Example 7
In the same manner as in Comparative Example 3, melt spinning, stretching, and heat treatment were performed, and a finishing oil was applied. Then, the fiber length was cut to 5 mm without mechanical crimping by a push-in crimper, and the single yarn fineness was 2.2 decitex. The polyester composite short fiber was obtained.
A wet short fiber nonwoven fabric was obtained in the same manner as in Example 7 using the obtained polyester composite short fiber.

Comparative Example 8
In the same manner as in Comparative Example 4, melt spinning, stretching, and heat treatment were carried out, and after applying a finishing oil agent, the fiber length was cut to 5 mm without applying mechanical crimping with a push-in crimper, and the single yarn fineness was 2.2 decitex. The polyester composite short fiber was obtained.
A wet short fiber nonwoven fabric was obtained in the same manner as in Example 7 using the obtained polyester composite short fiber.

  Table 2 shows the characteristic values and evaluation results of the composite short fibers and wet short fiber nonwoven fabrics obtained in Examples 7 to 12 and Comparative Examples 5 to 8.

As is clear from Table 2, in Examples 7 to 12, composite short fibers could be obtained with good spinning and stretching operability, and the dry heat shrinkage of the composite short fibers was low. For this reason, the obtained wet short fiber nonwoven fabric has good formation, has a low area shrinkage, can be bonded with good dimensional stability, and is composed of other polyester fibers. The adhesive strength was excellent.
On the other hand, in Comparative Example 5, since the melting point of the polylactic acid polymer was too low, it became difficult to melt-spin it as a composite fiber together with polyester A, and the spinning operability was poor. In Comparative Example 6, since the melting point of the polylactic acid-based polymer was too high, the composite short fiber could not melt the polylactic acid-based polymer by the thermal bonding treatment of the melting point of polyester A + 10 ° C., and the adhesive component was reduced. Therefore, the obtained wet short fiber nonwoven fabric had a low adhesive strength. In Comparative Examples 7 and 8, since the short fiber comprising only polyester A was used as the short fiber constituting the nonwoven fabric, the synergistic effect of polyester A and the polylactic acid polymer was not obtained as an effect at the time of bonding, and the adhesive strength was high. It became low.

Example 13
An undrawn yarn was obtained in the same manner as in Example 1, and the undrawn fiber that had been bundled into a 110,000 decitex tow-like shape was drawn and heat-treated in the same manner as in Example 1 and then pushed in. A crimper was applied with a crimping condition of a nip pressure of 0.39 MPa and a staffin pressure of 0.07 MPa, and a crimp of 5.6 crimps / 25 mm and a crimping rate of 4.1% was applied. After applying an oil mainly composed of polyoxyethylene alkyl ether as a finishing oil so as to have an adhesion amount of 0.2% by mass, it is cut to obtain a polyester composite short fiber having a single yarn fineness of 2.2 dtex and a fiber length of 5 mm. It was.
The obtained polyester composite short fiber is used with a simple airlaid tester shown in FIG. 4. First, the short fiber input from the sample input blower 13 is rotated by the defibrating blade rotating motor 15 through the defibrating blade rotating sprocket 16. A set of five sheets of the first defibrating blade 11 and the second defibrating wing 12 was defibrated and scattered and dropped. The falling short fibers were sucked by the suction box 14 at the bottom and deposited on the cotton collection conveyor 17 moving in the direction of the arrow to obtain a dry nonwoven web having a basis weight of 50 g / m ² (the basis weight adjustment was collected). This was done by changing the moving speed of the cotton conveyor 17).
Thereafter, in the same manner as in Example 1, partial thermal compression bonding was performed to obtain a dry short fiber nonwoven fabric having a basis weight of 50 g / m ² made of short fibers having a single yarn fineness of 2.2 dtex.
Moreover, the wet short fiber nonwoven fabric was obtained like Example 7 using the obtained polyester composite short fiber.

Examples 14-22
Various changes were made to the conditions (nip pressure, staffin pressure) for applying crimp with a push-in crimper as shown in Table 3, and the crimp type, the number of crimps, and the crimp rate shown in Table 3 were used. A polyester composite short fiber was obtained in the same manner as in Example 13, and a dry nonwoven fabric and a wet nonwoven fabric were obtained in the same manner as in Example 13.

As is clear from Table 3, Examples 13 to 22 were modified crimped forms in the polyester composite short fiber of Example 1, and were crimped forms satisfying the formula (3). There was no formation of fiber mass, the airlaid dry nonwoven fabric and wet nonwoven fabric obtained were good, the uniformity was excellent, the area shrinkage rate was low, and the adhesive strength was excellent.

Claims (5)

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 (TmA). A composite fiber composed of polyester A having a temperature of 100 to 150 ° C. and a polylactic acid polymer having a melting point of (TmA-30 ° C.) to (TmA + 30 ° C.). A polyester composite short fiber which is arranged so as to occupy at least a part of the surface and has a fiber length of 1 to 100 mm. Polyester A is a polyester composite short fiber according to claim 1, wherein the DSC curve showing the temperature-falling crystallization obtained from DSC satisfies the following formula (1).
b / a ≧ 0.05 (mW / mg · ° C.) (1)
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 according to claim 1 or 2, wherein the polyester composite short fiber is provided with a crimp satisfying the following condition (2), the fiber length is 1.0 to 30 mm, and the single yarn fineness is 0.3 to 20 dtex. Short fiber.
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 A short fiber nonwoven fabric comprising a web containing only the polyester composite short fiber according to claim 1, wherein at least a part of the polyester composite short fiber is melted to form an adhesive portion. The short fiber nonwoven fabric according to claim 4, wherein the area shrinkage ratio is 10% or less in an atmosphere at a temperature (TmA-30 ° C) lower by 30 ° C than the melting point (TmA) of polyester A of the polyester composite short fiber.