JP5344963B2 - Short fiber nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a short fiber nonwoven fabric capable of decreasing the processing temperature in heat-bonding treatment, hardly causing a decrease in adhesive strength when used in a high temperature atmosphere, excellent in bulkiness and flexibility, and having excellent texture and mechanical properties. <P>SOLUTION: The short fiber nonwoven fabric comprises a web comprising a sheath-core composite short fiber and a composite short fiber having latent crimping performance and developing crimping by heat treatment, wherein the sheath-core composite short fiber includes a polyester A comprising a dicarboxylic acid ingredient mainly composed of terephthalic acid and a diol ingredient comprising 50 mol% or more of 1,6-hexanediol, containing a 0.01-5.0 mass% nucleating agent, and having a 100-150&deg;C melting point (Tm), and an amorphous polyester B, the polyester A forms the sheath, the polyester B forms the core, and both of the polyesters A and B of a sheath core fiber are fused to comprise adhesive ingredients. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention uses a core-sheath type composite short fiber composed of polyester and amorphous polyester having a low melting point and excellent crystallinity as a binder fiber, and a composite short fiber having latent crimping performance as a main fiber, and is bulky. And a short fiber nonwoven fabric excellent in flexibility, mechanical properties, and formation.

  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 the field of sanitary materials, various short fiber nonwoven fabrics in which constituent fibers are bonded using binder fibers have been proposed. Since most of these short fiber nonwoven fabrics are made of polyester fibers, it is preferable to use fibers made of polyester polymers as binder fibers as adhesive components from the viewpoint of recycling.

  For example, as such a short fiber nonwoven fabric, a core-sheath type composite short fiber having a polyethylene terephthalate copolymer copolymerized with an isophthalic acid component as a sheath is used as a binder fiber, and a short fiber made of polyethylene terephthalate is used as a main fiber. The thing which was done is mentioned. Since the binder fiber used for this short fiber nonwoven fabric consists of a high melting point core and a low melting point sheath, only the sheath melts into an adhesive component during the thermal bonding process, and the core does not melt. The fiber form is retained.

  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, when the obtained short fiber nonwoven fabric is used in a high temperature atmosphere, there is a problem that the adhesive strength is reduced or deformed, and this binder fiber has a high heat shrinkage rate, and shrinkage during the heat bonding treatment. However, the obtained short fiber nonwoven fabric has a problem of poor formation and poor flexibility.

  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 copolymer of the sheath part is crystalline and has a clear melting point, so the heat shrinkage rate is small, the shrinkage during thermal bonding treatment when making a nonwoven fabric is small, the formation is good, and the flexibility In addition, a nonwoven fabric having excellent heat resistance when used in a high-temperature atmosphere can be obtained.

  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.

JP 2006-118066 A

  The present invention solves the above-mentioned problems, and can reduce the processing temperature during the thermal bonding treatment, and there is little decrease in adhesive strength when used in a high-temperature atmosphere, resulting in high bulkiness and flexibility. It is a technical problem to provide a short fiber nonwoven fabric that is excellent in properties and excellent in formation and mechanical properties.

The inventors of the present invention have arrived at the present invention as a result of studies to solve the above problems.
That is, in the present invention, the dicarboxylic acid component is composed only of terephthalic acid , the diol component is composed of only 1,6-hexanediol and ethylene glycol, or 1,6-hexanediol and 1,4-butanediol. 1,6-hexanediol is 60 to 95 mol%, 0.01 to 5.0 mass% of a crystal nucleating agent is contained, melting point (Tm) is 100 to 150 ° C., polyester A, and flow start temperature (R ) Is 105 to 155 ° C., and the difference between the flow start temperature and the melting point of polyester A (R-Tm) is amorphous polyester B of + 5 ° C. or less. A sheath, a core-sheath type composite short fiber having a core-sheath shape in which polyester B serves as a core, and a composite short fiber having latent crimping performance that develops crimp by heat treatment It consists web containing, it is an gist short fiber nonwoven fabric, characterized in that forms a polyester A, B are both melted to the adhesive component of the core-sheath composite short fibers.

  The core-sheath type composite short fiber constituting the short fiber nonwoven fabric of the present invention has polyester A having a low melting point and excellent crystallinity arranged in the sheath part, so there is no welding between single yarns during spinning. Further, since the heat treatment can be performed at a high temperature in the stretching and heat treatment processes, the dry heat shrinkage can be reduced. Therefore, the short fiber nonwoven fabric of the present invention is excellent in formation, flexibility and mechanical properties, and has a small decrease in adhesive strength when used in a high temperature atmosphere.

  In addition, since the core-sheath type composite short fiber is obtained by arranging amorphous polyester B in the core part, the processing temperature when the main fiber is thermally bonded can be lowered by melting the binder fiber. It is advantageous in terms of cost, and by combining two kinds of polyesters, it has appropriate flow characteristics and has a strong adhesive force. Therefore, the short fiber nonwoven fabric of the present invention is excellent in mechanical properties (nonwoven fabric strength) and has less generation of fluff on the surface.

  Furthermore, the short fiber nonwoven fabric of the present invention uses composite short fibers having latent crimping performance as the main fiber, so that crimping is manifested by heat treatment, so that the bulkiness and flexibility are excellent. Can do.

  Thus, the short fiber nonwoven fabric of the present invention can be widely used for clothing, industrial materials, sanitary materials and the like.

It is an example of the DSC curve which shows temperature-fall crystallization calculated | required from DSC of the polyester A which comprises the core-sheath-type composite short fiber in this invention.

Hereinafter, the present invention will be described in detail.
The short fiber nonwoven fabric of the present invention comprises a composite short fiber having latent crimping performance that develops crimps by heat treatment as a main fiber, and a core-sheath type composite short fiber composed of polyester A and polyester B described in detail below as a binder. It consists of a web containing both short fibers as a fiber, and both the polyesters A and B of the core-sheath type composite short fiber are melted to form an adhesive component.

  In other words, the short fiber nonwoven fabric of the present invention bonds the main fiber by melting both the polyester A and the polyester B of the core-sheath type composite short fiber in the heat bonding treatment when melting the core-sheath type composite short fiber as the binder fiber. It is what is used as an adhesive component. Polyester B is an amorphous polymer that melts when it is melted, and polyester A is melted because it is a crystalline polymer. When polyester B is melted, it has high fluidity. The core-sheath type composite short fiber in the present invention is a binder fiber having a strong adhesive force.

  And since the polyester A and B components are melted together, the adhesive component is uniformly distributed in the thickness direction of the nonwoven fabric, and the adhesion between the main fibers is uniform and sufficiently adhered. Excellent (nonwoven fabric strength) and less fuzz on the surface. In addition, since both polyesters A and B are melted, the obtained short fiber nonwoven fabric is excellent in flexibility.

  The short fiber nonwoven fabric of the present invention may be either a dry nonwoven fabric or a wet nonwoven fabric, and the basis weight is not particularly limited.

  The short fiber nonwoven fabric of the present invention is composed of a core-sheath type composite short fiber and a web containing a composite short fiber having latent crimping performance that develops crimp by heat treatment. In the non-woven fabric, the latent crimping performance of the composite short fiber as the main fiber may or may not be exhibited.

  That is, in the short fiber nonwoven fabric of the present invention, the core-sheath type composite short fiber serving as the binder fiber is melted to form an adhesive component, but the latent crimp of the main fiber is performed during the heat bonding process for melting the binder fiber. It may be in a state where the performance is expressed, or may be in a state where the latent crimp of the main fiber is not expressed in the heat bonding treatment for melting the binder fiber. In the latter case, the nonwoven fabric obtained by once melting the binder fiber is further subjected to a heat treatment to develop the latent crimp performance of the main fiber.

  Among them, the short fiber nonwoven fabric of the present invention melts the binder fiber without developing the latent crimping performance of the composite short fiber as a main fiber in order to obtain a good texture when creating a web. It is preferable that latent crimps of the main fibers are developed during the heat bonding treatment. Thereby, it can be set as the nonwoven fabric excellent in formation, bulkiness, and the softness | flexibility.

  And it is preferable that the mixing rate of the main fiber in a short fiber nonwoven fabric is 10-90 mass%, and it is preferable that it is 30-70 mass% especially. When the proportion of the main fiber exceeds 90% by mass, the proportion of the binder fiber is small, the adhesive component is reduced, and the adhesive force is lowered. Therefore, the short fiber nonwoven fabric is inferior in mechanical properties (strength and the like). On the other hand, when the ratio of the main fiber is less than 10% by mass, the ratio of the binder fiber is large and the adhesive component is excessive, so that the short fiber nonwoven fabric is inferior in flexibility and mechanical properties (strength and the like). Is also poor in bulkiness.

The core-sheath type composite short fiber in the present invention is composed of polyester A and polyester B, and is a composite short fiber in which polyester A is arranged in the sheath part and polyester B is arranged in the core part. That is, the core-sheath type composite short fiber in the present invention exhibits the above-described core-sheath shape in the cross-sectional shape of a single yarn (the shape of a cross section cut perpendicularly along the fiber axis direction). In addition, as such a core-sheath shape, you may have a several core part, and when it has a several core part, it is preferable that the number of core parts shall be 2-10 pieces.

First, polyester A will be described. Polyester A is composed of dicarboxylic acid component only terephthalic acid , diol component only 1,6-hexanediol and ethylene glycol, or 1,6-hexanediol and 1,4-butanediol. 6-Hexanediol is a copolyester having 60 to 95 mol% and a melting point of 100 to 150 ° C.

  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 is Ru Monodea consisting only terephthalic acid as the dicarboxylic acid component.

The diol component is only 1,6-hexanediol (hereinafter referred to as HD) and ethylene glycol (hereinafter referred to as EG) , or 1,6-hexanediol and 1,4-butanediol (hereinafter referred to as BD). Consists of only. In the diol component, HD is 60 to 95 mol%. In addition, when HD is less than 50 mol%, melting | fusing point will exceed 150 degreeC.

As the diol component, EG or BD is 5 to 40 mol% in the diol component .

  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 the crystallization rate during cooling can be improved by containing a crystal nucleating agent. And it is preferable to satisfy the formula (1) described later. Since polyester A has such excellent crystallinity, it can be heat-treated at high temperatures in the drawing and heat-treating steps without causing welding between single yarns in the melt-spinning step when fiberizing. Therefore, a fiber having a low dry heat shrinkage rate can be obtained.

  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.

And as for polyester A, it is preferable that the DSC curve which shows the temperature-fall crystallization calculated | required from DSC satisfies the following (1) Formula, and it is preferable that it is especially 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 intended effect of the present invention, b / a is preferably 0.5 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 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. As shown in FIG. 1, a is the temperature A1 (° C.) of the intersection of the tangent line and the base line with the maximum inclination in the DSC curve indicating the temperature-falling crystallization, the tangent line and the base line with the minimum inclination. Is the difference (A1−A2) from the temperature A2 (° C.) at the intersection of the two, and b is the difference (B1−B2) between the baseline heat amount B1 (mW) and the peak top heat amount B2 (mW) at the peak top temperature. ) Divided by the sample amount (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 specific copolymer composition of the polyester and the content of the crystal nucleating agent within the above range. It becomes.

  Next, polyester B will be described. Polyester B is an amorphous polyester having a flow start temperature (R) of 105 to 155 ° C., and a difference (R−Tm) between the flow start temperature and the melting point (Tm) of polyester A is + 5 ° C. or less. It is.

  That is, the core-sheath type composite short fiber in the present invention is one in which both polyester A and polyester B are melted by heat bonding treatment to form an adhesive component, but usually the heat bonding temperature is arranged on the fiber surface. Since it is performed at a temperature 10 ° C. higher than the melting point of the polyester A, in order for the polyester B to melt at such a heat bonding treatment temperature, the flow start temperature of the polyester B is 5 even if it is higher than the melting point of the polyester A. It is necessary that the temperature be not higher than ° C., and among these, it is preferably lower than the melting point of polyester A.

  Moreover, although the flow start temperature of the polyester B is 105-155 degreeC, it is preferable that it is 110-140 degreeC, especially 115-135 degreeC especially.

  When the flow start temperature of the polyester B is less than 105 ° C., the treatment temperature in the stretching and heat treatment steps cannot be increased, and a short fiber having a high dry heat shrinkage rate is obtained. On the other hand, when it exceeds 155 ° C., it is necessary to increase the heat bonding treatment temperature when obtaining the product, and the processability and the economical efficiency are inferior.

  As the polyester B, those mainly composed of polyalkylene terephthalate such as polyethylene terephthalate (PET), polybutylene terephthalate, and polytrimethylene terephthalate are preferable. And in order to set it as the thing of said flow start temperature, it is preferable to use what was copolymerized the following components.

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

  Among them, as polyester B, it is preferable to use PET copolymerized with isophthalic acid, and among them, those obtained by copolymerizing 25 to 40 mol% of isophthalic acid are preferable. When the copolymerization amount of isophthalic acid is less than 25 mol%, the flow start temperature becomes high and tends to exceed 155 ° C. On the other hand, if it exceeds 40 mol%, the flow start temperature tends to be low and tends to be less than 105 ° 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 kind or two or more kinds of various additives such as a matting agent, a plasticizer, a pigment, an antistatic agent, a flame retardant, and a dyeing agent may be added.

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

  In the core-sheath type composite short fiber in the present invention, the polyester A having excellent crystallinity is arranged in the core part and the amorphous polyester B is arranged in the sheath part as described above. Welding between yarns does not occur, drawing and heat treatment can be performed at high temperature, and a fiber having a low heat shrinkage rate can be obtained. Specifically, the core-sheath type composite short fiber in the present invention preferably has a dry heat shrinkage rate of (Tm-30) ° C. of 7% or less, particularly 5% when the melting point of polyester A is Tm. It is preferable that it is below, Furthermore, it is preferable to set it as 4.8 to 0.5%.

  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 core-sheath type composite short fiber is used as a sample, and the initial load is 50 mg / dtex. The measurement is made by measuring with a grip interval of 25 mm and a processing temperature of (Tm-30) ° C.

  The short fiber nonwoven fabric of the present invention obtained by using the short fiber as a binder fiber by setting the dry heat shrinkage rate of the core-sheath type composite short fiber at (Tm-30) ° C. to 7% or less is a thermal bonding treatment. The thermal shrinkage at the time is small, the web shrinkage ratio comparing the area of the web before the thermal bonding treatment and the area of the nonwoven fabric obtained after the thermal bonding treatment is small, and the resulting nonwoven fabric has excellent formation and flexibility . On the other hand, when the dry heat shrinkage rate at (Tm-30) ° C. exceeds 7%, the shrinkage of the binder fiber is increased during the heat bonding treatment, the web shrinkage rate is increased, and the resulting nonwoven fabric has a poor texture. It ’s also less flexible.

  In addition, the short fiber nonwoven fabric of the present invention uses, as the main fiber, a short fiber of a composite fiber having a latent crimp performance that develops crimp by heat treatment.

  As the composite short fiber having such latent crimping performance, a fiber that exhibits a spiral crimp by heat treatment is preferable, and the composite form is preferably a composite short fiber using two kinds of polymers, an eccentric core-sheath type, Examples include a side-by-side type and a multi-layered type, among which a side-by-side type is preferable.

  The composite short fiber having latent crimping performance is preferably one that develops crimps of 50 pieces / 25 mm or more by heat treatment at 170 ° C., particularly one that expresses crimps of 50 pieces / 25 mm to 100 pieces / 25 mm. .

  The number of crimps referred to in the present invention is set in an oven (heat treatment machine) having an atmospheric temperature of 170 ° C. with no load and subjected to heat treatment for 15 minutes to develop crimps, and a load of 50 mg / dtex is applied. A value obtained by measuring the number of crimps per length is converted per 25 mm length.

  In addition, when the fiber length is short and measurement is difficult, the measurement is performed from the fiber before being cut into short fibers.

  As the composite short fiber having such latent crimping performance, it is preferable to use polyester as two kinds of polymers, and it is preferable to use polyethylene terephthalate (hereinafter referred to as PET) and a copolyester. As the copolyester, a polyester obtained by copolymerizing 2 to 6 mol% of aromatic dicarboxylic acid with respect to the total acid component (hereinafter referred to as copolyester M), and isophthalic acid (hereinafter referred to as IPA) with respect to the total acid component. It is preferable to use a polyester (hereinafter referred to as copolymer polyester N) obtained by copolymerizing 1 to 9 mol% and 2 to 8 mol% of bisphenol A ethylene oxide adduct (hereinafter referred to as BAEO).

  In the copolymerized polyester M, 5-sodium sulfoisophthalic acid (hereinafter referred to as SIP) is preferable as the aromatic dicarboxylic acid. When the copolymerization amount of SIP is less than 2 mol%, the difference in melt viscosity and heat shrinkage between PET and PET does not increase, and the latent crimp performance tends to be insufficient. On the other hand, when it exceeds 6 mol%, the melting point of the polyester is lowered, and it is difficult to obtain composite short fibers (short fibers).

  In copolymerized polyester N, if the copolymerization amount of IPA is less than 1 mol% or the copolymerization amount of BAEO is less than 2 mol%, the difference in melt viscosity and thermal shrinkage from PET will not increase. The latent crimp performance tends to be insufficient. On the other hand, when IPA exceeds 9 mol% or the copolymerization amount of BAEO exceeds 8 mol%, the melting point of the polyester is lowered, making it difficult to obtain composite short fibers (short fibers). The strength of the polyester short fiber is reduced.

  BAEO is preferably one in which 2 to 10 mol of ethylene oxide is added to 1 mol of bisphenol A, and more preferably 2 to 5 mol of ethylene oxide is added.

  And the composite ratio of the two types of polymers in the composite short fiber having latent crimping performance is preferably 10/90 to 90/10 in mass ratio, more preferably 30/70 to 70/30. .

In the composite short fiber having latent crimping performance, a stabilizer such as a phosphate ester compound or a hindered phenol compound, a cobalt compound, a fluorescent whitening agent, a dye, etc., as long as the effects of the present invention are not impaired. One or more additives such as a color improver, a matting agent such as titanium dioxide, a plasticizer, a pigment, an antistatic agent, a flame retardant, and an easy dyeing agent may be added. When the short fiber nonwoven fabric is a dry nonwoven fabric, both the core-sheath type composite short fiber and the composite short fiber having latent crimping performance are preferably 25 to 100 mm, and more preferably 30 to 80 mm. Moreover, when making the short fiber nonwoven fabric of this invention into a wet nonwoven fabric, it is preferable that the fiber length of these short fibers shall be 1-30 mm, and it is preferable to set it as 3-20 mm especially.

  When the dry nonwoven fabric is used, if the fiber length of the short fiber is less than 25 mm, the fiber falls off during defibration with a card machine, so that the operability is deteriorated. On the other hand, if it exceeds 100 mm, the defibration property in the card machine is deteriorated, and the resulting nonwoven fabric is inferior in formation and uniformity. In addition, when the wet nonwoven fabric is used, if the fiber length of the short fiber is less than 1 mm, the fiber is welded or glued by heat at the time of cutting. On the other hand, when the thickness exceeds 30 mm, a fiber lump is easily generated when a web is obtained with a paper machine, and the resulting nonwoven fabric is inferior in formation and uniformity.

  Moreover, it is preferable that the single yarn fineness of the core-sheath type composite short fiber and the composite short fiber having latent crimping performance is 1 to 15 dtex. When the single yarn fineness is less than 1 dtex, single yarn cutting frequently occurs in the spinning and drawing processes, the operability is deteriorated, and the quality of the resulting nonwoven fabric is likely to be lowered. On the other hand, when the single yarn fineness exceeds 15 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.

Next, the manufacturing method of the short fiber nonwoven fabric (dry type) of this invention is demonstrated using an example.
Composite staple fiber with latent crimping performance is the main fiber, core-sheath type composite short fiber is the binder fiber, binder fiber and main fiber are weighed at an arbitrary ratio, blended using a card machine, defibrated and dried Create a web. The obtained web is subjected to a thermal bonding treatment at a temperature at which the melting point (Tm) of polyester A + 10 ° C. or higher and the latent crimp of the main fiber can be expressed by a continuous heat treatment machine, and the binder fiber is melted. A crimped crimp is obtained to obtain a dry short fiber nonwoven fabric in which crimped staple fibers are integrated.

Next, the manufacturing method of the short fiber nonwoven fabric (wet) of this invention is demonstrated using an example.
The composite short fiber with latent crimping performance is the main fiber, the core-sheath type composite short fiber is the binder fiber, the binder fiber and the main fiber are weighed at an arbitrary ratio, put into a pulp disintegrator, and stirred (mixed cotton, unwinding) ) A wet nonwoven web is prepared from the obtained sample using a paper machine. After dehydrating excess moisture of this wet nonwoven web, the melting point (Tm) of polyester A + 10 ° C. or higher, and heat bonding treatment is performed at a temperature at which the latent crimp of the main fiber can be expressed, and the binder fiber is melted. A crimped main fiber is developed to obtain a wet short fiber nonwoven fabric integrated with the crimped main fiber.

Moreover, the manufacturing method of the core-sheath-type composite short fiber used as a binder fiber in the short fiber nonwoven fabric 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, and melt spinning is performed so that polyester A serves as a sheath and polyester B serves as a core. 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 using a stuffing box or the like, and the fiber is cut into a target fiber length to obtain a core-sheath composite short fiber.
In addition, when obtaining a wet nonwoven fabric, it is preferable to set it as the core-sheath-type composite short fiber to which the crimp is not provided, without providing a mechanical crimp.

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 [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.
(B) Melting point of polyester A, DSC curve showing temperature drop crystallization determined from DSC Measured by the above method.
(C) Flow start temperature of polyester constituting polyester B and main fiber Using a Flotester (Shimadzu CFT-500 type), under conditions of a load of 9.8 MPa and a nozzle diameter of 0.5 mm, the initial temperature is 50 ° C. to 10 ° C. The temperature was raised at a rate of / min and determined as the temperature at which the polymer began to flow out of the die.
(D) Melting point of polyester constituting main fiber Using a differential scanning calorimeter (Diamond DSC, manufactured by Perkin Elmer Co., Ltd.), the melting point was defined as the temperature giving the extreme value of the melting absorption curve measured at a heating rate of 20 ° C./min. .
(E) 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. 1H-NMR was measured with a 400-type NMR apparatus, and obtained from the integrated intensity of the proton peak of each copolymer component in the obtained chart.
(F) Dry heat shrinkage (%) of core-sheath type composite short fiber
Measurement was performed by the method described above.
(G) Evaluation of nonwoven fabric Formation The formation of the surface of the obtained nonwoven fabric was visually evaluated in two stages: good (◯) and defective (×).
2. Flexibility (feel)
The softness of the obtained nonwoven fabric was judged by tactile sensation and evaluated in two stages: good (◯) and bad (×).
3. Mechanical properties (tensile strength and heat resistance)
〔Tensile strength〕
About the obtained nonwoven fabric, the tensile strength (N) was measured by the standard time A method (strip method) of tensile strength and elongation rate of JIS L1096 8.12. The width of the test piece was set to 5.0 cm by the cut strip method, a constant speed extension type tester was used, and the test conditions were set to a grip interval of 20 cm and a tensile speed of 20 cm / min. At this time, it measured in 25 degreeC atmosphere.
〔Heat-resistant〕
Said tensile strength was measured in 70 degreeC atmosphere, and the strength retention was computed by the following formula. The strong retention rate is an index indicating heat resistance, and is preferably 70% or more.
Tensile strength retention (%) = [(tensile strength in 70 ° C. atmosphere) / (tensile strength in 25 ° C. atmosphere)] × 100
4). Bulkiness The obtained non-woven fabric is cut into 20 cm × 20 cm to make a sample, and 10 cm of the samples are stacked and an acrylic plate (370 g) of 25 cm × 25 cm × 5 mm is placed, and a weight of 1 kg is placed on the acrylic plate. The height of the center of each of the four sides of the lower surface was measured, and the average value of the four points was obtained.
For each of the dry nonwoven fabric and the wet nonwoven fabric, the average value was evaluated in three stages as follows.
(Dry nonwoven fabric)
○: Height is 40.0 mm or more Δ: Height is 25.0 mm or more and less than 40.0 mm ×: Height is less than 25.0 mm (wet nonwoven fabric)
○: The height is 15.0 mm or more Δ: The height is 10.0 mm or more and less than 15.0 mm ×: The height is less than 10.0 mm

Example 1
(Core-sheath type composite short fiber: binder fiber)
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 polyester B, the polyester of a in Table 3 was used.
The polyester A chip and the polyester B chip were supplied to the composite spinning apparatus, and the melt spinning was performed with the polyester A serving as the sheath and the polyester B serving as the core, and the mass ratio of both components being 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.
The unstretched yarn is bundled into a 110,000 dtex tow-shaped unstretched fiber and stretched at a stretch ratio of 3.75 times and a stretch temperature of 50 ° C., and then heat treated with a heat drum (temperature 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 core-sheath type composite short fiber having a single yarn fineness of 2.2 dtex.
(Composite short fiber with latent crimp performance: Main fiber)
A composite short fiber obtained by laminating PET and a copolymerized PET obtained by copolymerizing 4.5 mol% of SIP in a side-by-side manner at a mass ratio of 50/50, provided with mechanical crimping, having a fiber length of 51 mm, A composite short fiber (latent crimped cotton <C81> manufactured by Unitika Fiber Co., Ltd.) that develops crimps of 70 pieces / 25 mm by heat treatment at a yarn fineness of 2.2 dtex and 170 ° C. was used.
(Dry short fiber nonwoven fabric)
A dry web was prepared by passing the mixing ratio of the binder fiber and the main fiber through a card machine at a mass ratio of 50/50 (binder fiber / main fiber). The obtained dry web is heat bonded for 1 minute in a continuous heat treatment machine at a temperature of 160 ° C. and an air volume of 20 m ³ / min, almost all binder fibers are melted to become an adhesive component, and the latent crimp of the main fibers is reduced. A dry short fiber nonwoven fabric having a weight per unit area of 100 g / m ² was obtained.

Example 2
A core-sheath type composite short fiber was obtained in the same manner as in Example 1 except that the polyester B of Table 3 was used as the polyester B of the core-sheath type composite short fiber. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Example 3
A core-sheath type composite short fiber was obtained in the same manner as in Example 1 except that the polyester c in Table 3 was used as the polyester B of the core-sheath type composite short fiber. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Examples 4-5
A dry short fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the mixing ratio of the binder fiber and the main fiber was changed to the mass ratio shown in Table 1.

Example 6
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 melting point of 130 ° C. and b / a of 0.11 was used. A core-sheath type composite short fiber was obtained in the same manner as in Example 1 by using the polyester of a in Table 2 as the polyester B.
And the same composite short fiber as what was used in Example 1 was used as main fiber, and it carried out similarly to Example 1, and obtained the dry short fiber nonwoven fabric.

Example 7
A core-sheath type composite short fiber was obtained in the same manner as in Example 6 except that the polyester b shown in Table 3 was used as the polyester B of the core-sheath type composite short fiber. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Example 8
A core-sheath composite short fiber was obtained in the same manner as in Example 6 except that the polyester c of Table 3 was used as the polyester B of the core-sheath composite short fiber. Further, a dry short fiber nonwoven fabric was obtained in the same manner as in Example 1.

Examples 9-10
A dry short fiber nonwoven fabric was obtained in the same manner as in Example 6 except that the mixing ratio of the binder fiber and the main fiber was changed to the mass ratio shown in Table 1.

Example 11
A composite short fiber in which PET and a copolymerized PET obtained by copolymerizing 4.0 mol% of IPA and 4.0 mol% of BAEO are bonded in a side-by-side manner at a mass ratio of 50/50. Combined short fiber with a crimp of 65mm / 25mm by heat treatment at a fiber length of 51mm, single yarn fineness of 2.2 decitex and 170 ° C (latent crimped cotton <T81> manufactured by Unitika Fiber) Was used.
A dry short fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the binder fiber used in Example 1 was used and the thermal bonding treatment temperature in a continuous heat treatment machine when producing the nonwoven fabric was 140 ° C.

Example 12
A dry short fiber nonwoven fabric was obtained in the same manner as in Example 11 using the composite short fiber used in Example 13 as the main fiber and the core-sheath type composite short fiber used in Example 6 as the binder fiber.

Comparative Example 1
A dry short fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the main fiber was a polyester short fiber having a single yarn fineness of 2.2 dtex consisting of only PET having an intrinsic viscosity of 0.64 and a fiber length of 51 mm.

Comparative Example 2
As a binder fiber, a composite short fiber having a polyethylene terephthalate copolymer copolymerized with an isophthalic acid component as a sheath part and a polyethylene terephthalate as a core part, a single yarn fineness 2.2 decitex, a fiber length 51 mm, 100 ° C., A core-sheath type composite short fiber (Melty <3380> manufactured by Unitika Fiber Co., Ltd.) having a dry heat shrinkage rate of 15.2% in 15 minutes was used.
A dry short fiber nonwoven fabric was obtained in the same manner as in Example 1 using the composite short fiber used in Example 1 as the main fiber.

  Table 1 shows the characteristic values and evaluation results of the dry short fiber nonwoven fabrics obtained in Examples 1 to 12 and Comparative Examples 1 and 2.

  As is clear from Table 1, in Examples 1 to 12, since the binder fiber was a core-sheath type composite fiber composed of polyester A and polyester B, the dry heat shrinkage rate was low, and thermal bonding treatment when obtaining a nonwoven fabric The shrinkage was small and the adhesive property was excellent. Therefore, the obtained dry short fiber nonwoven fabric was excellent in formation, flexibility, mechanical properties, and heat resistance. Furthermore, since the main fiber was a composite short fiber having latent crimping performance, crimping was manifested by the thermal bonding treatment when the nonwoven fabric was produced, and the bulkiness and flexibility were excellent.

  On the other hand, in Comparative Example 1, since the short fiber made of PET having no latent crimping performance was used as the main fiber, the obtained dry short fiber nonwoven fabric was poor in bulkiness and flexibility. In Comparative Example 2, since the binder fiber was composed only of amorphous polyester, the dry heat shrinkage ratio was high, and the shrinkage in the heat bonding treatment when obtaining the nonwoven fabric was large. In other words, both flexibility and heat resistance were poor.

Example 13
(Core-sheath type composite short fiber: binder fiber)
Using the same polyester A and polyester B as in Example 1 and performing melt spinning, stretching and heat treatment in the same manner as in Example 1 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 core-sheath type composite short fiber having a single yarn fineness of 2.2 dtex.
(Composite short fiber with latent crimp performance: Main fiber)
A composite short fiber obtained by adhering PET and copolymerized PET obtained by copolymerizing 4.5 mol% of SIP to a side-by-side type at a mass ratio of 50/50, and having a fiber length of 5 mm to which no mechanical crimp is imparted and a single yarn Polyester short fibers (latent crimped cotton <C81> manufactured by Unitika Fiber Co., Ltd.) that developed crimps of 70 pieces / 25 mm by heat treatment at a fineness of 2.2 dtex and 170 ° C. were used.
(Wet short fiber nonwoven fabric)
The mixing ratio of the binder fiber and the main fiber was mixed at a mass ratio of 50/50 (binder fiber / main fiber), put into a pulp disintegrator (manufactured by Kumagaya Rikyu 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). After dehydrating excess water from the wet nonwoven web, the paper was heat-bonded for 10 minutes in a continuous heat treatment machine at a temperature of 160 ° C. and an air volume of 20 m ³ / min, and almost all the binder fibers were melted as an adhesive component. And the wet short fiber nonwoven fabric of 50 g / m < ² > of fabric weights in which the latent crimp of main fiber was expressed was obtained.

Example 14
A core-sheath type composite short fiber was obtained in the same manner as in Example 13 except that the polyester b shown in Table 3 was used as the polyester B of the core-sheath type composite short fiber. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 13.

Example 15
A core-sheath composite short fiber was obtained in the same manner as in Example 13 except that the polyester c of Table 3 was used as the polyester B of the core-sheath composite short fiber. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 13.

Examples 16-17
A wet short fiber nonwoven fabric was obtained in the same manner as in Example 13 except that the mixing ratio of the binder fiber and the main fiber was changed to the mass ratio shown in Table 1.

Example 18
Using the same polyester A and polyester B as in Example 6 and performing melt spinning, stretching and heat treatment in the same manner as in Example 1 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 core-sheath type 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 13 except that the composite short fiber used in Example 13 was used as the main fiber.

Example 19
A core-sheath type composite short fiber was obtained in the same manner as in Example 18 except that the polyester B in Table 3 was used as the polyester B of the core-sheath type composite short fiber. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 13.

Example 20
A core-sheath composite short fiber was obtained in the same manner as in Example 18 except that the polyester c in Table 3 was used as the polyester B of the core-sheath composite short fiber. Further, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 13.

Examples 21-22
A wet short fiber nonwoven fabric was obtained in the same manner as in Example 13 except that the mixing ratio of the binder fiber and the main fiber was changed to the mass ratio shown in Table 1.

Example 23
A composite short fiber in which PET and a copolymerized PET obtained by copolymerizing 4.0 mol% of IPA and 4.0 mol% of BAEO are bonded in a side-by-side manner at a mass ratio of 50/50. Polyester short fibers (65% / 25mm crimped by a heat treatment at a fiber length of 5 mm, single yarn fineness of 2.2 dtex, and 170 ° C. (latent crimped cotton manufactured by Unitika Fiber Co., Ltd. <T81>) ) Was used.
A wet short fiber nonwoven fabric was obtained in the same manner as in Example 13 except that the binder fiber used in Example 13 was used and the thermal bonding treatment temperature in a continuous heat treatment machine when producing the nonwoven fabric was 140 ° C.

Example 24
The composite short fiber used in Example 23 was used as the main fiber, the short fiber used in Example 18 was used as the binder fiber, and the thermal bonding treatment temperature in the continuous heat treatment machine when producing the nonwoven fabric was 140 ° C. Obtained a wet short fiber nonwoven fabric in the same manner as in Example 18.

Comparative Example 3
Wet short fibers in the same manner as in Example 13 except that the main fibers were single yarn fineness 2.2 dtex consisting only of PET having an intrinsic viscosity of 0.64 and polyester short fibers (no mechanical crimping) having a fiber length of 5 mm. A nonwoven fabric was obtained.

Comparative Example 4
As a binder fiber, a core-sheath type composite short fiber having a polyethylene terephthalate copolymer copolymerized with an isophthalic acid component as a sheath part and polyethylene terephthalate as a core part, having a single yarn fineness of 2.2 dtex and a fiber length of 5 mm ( A polyester short fiber (Melty <3380> manufactured by Unitika Fiber Co., Ltd.) having a dry heat shrinkage rate of 15.2% at 100 ° C. for 15 minutes was used.
Using the composite short fiber used in Example 13 as the main fiber, a wet short fiber nonwoven fabric was obtained in the same manner as in Example 13.

  Table 2 shows the characteristic values and evaluation results of the wet short fiber nonwoven fabrics obtained in Examples 13 to 24 and Comparative Examples 3 to 4.

  As is apparent from Table 2, in Examples 13 to 24, the binder fiber was a core-sheath type composite fiber composed of polyester A and polyester B, and thus the dry heat shrinkage rate was low, and the thermal bonding treatment when obtaining a nonwoven fabric The shrinkage in the resin was small and the adhesiveness was excellent. Therefore, the obtained wet short fiber nonwoven fabric was excellent in formation, flexibility, mechanical properties, and heat resistance. Furthermore, since the main fiber was a composite short fiber having latent crimping performance, crimping was manifested by the thermal bonding treatment when the nonwoven fabric was produced, and the bulkiness and flexibility were excellent.

On the other hand, in Comparative Example 3, since the short fiber made of PET having no latent crimping performance was used as the main fiber, the obtained wet short fiber nonwoven fabric was poor in bulkiness and flexibility. In Comparative Example 4, since the binder fiber was composed only of amorphous polyester, the dry heat shrinkage rate was high, and the shrinkage in the heat bonding treatment when obtaining the nonwoven fabric was large. In other words, both flexibility and heat resistance were poor.

Claims (3)

The dicarboxylic acid component is composed only of terephthalic acid , the diol component is composed of only 1,6-hexanediol and ethylene glycol, or only 1,6-hexanediol and 1,4-butanediol. Of polyester A having a melting point (Tm) of 100 to 150 ° C and a flow starting temperature (R) of 105 to 155 ° C. The difference between the flow start temperature and the melting point of polyester A (R-Tm) is amorphous polyester B having a temperature of + 5 ° C. or less. Polyester A is a sheath portion and polyester B is a cross-sectional shape of a single yarn. From a web containing a core-sheath type composite short fiber exhibiting a core-sheath shape as a core part, and a composite short fiber having latent crimping performance that develops crimps by heat treatment Ri, short fiber nonwoven fabric, characterized in that forms a polyester A, B are both melted to the adhesive component of the core-sheath composite short fibers. The short fiber nonwoven fabric according to claim 1, wherein a DSC curve showing temperature-fall crystallization determined from DSC of polyester A constituting the core-sheath composite short fiber 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 where the slope is maximum in the DSC curve indicating the temperature-falling crystallization, and the temperature A2 (° C.) 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. A composite short fiber having latent crimping performance is a composite of polyethylene terephthalate and a copolymer polyester, and the copolymer polyester is a polyester obtained by copolymerizing 2 to 6 mol% of an aromatic dicarboxylic acid with respect to the total acid component, The short fiber nonwoven fabric according to claim 1 or 2, which is a polyester obtained by copolymerizing 1 to 9 mol% of isophthalic acid and 2 to 8 mol% of an ethylene oxide adduct of bisphenol A with respect to the total acid component.