JP4820211B2 - Self-extensible thermoadhesive conjugate fiber and method for producing the same - Google Patents

Abstract

An essential object of the invention is to provide a low-modulus, self-extensible thermal-adhesive bicomponent fiber comprising polyethylene terephthalate as the fiber-forming resin component thereof and capable of producing a nonwoven fabric or a fiber structure that has a high adhesive strength and is bulky and well drapable. The object of the invention is attained by a self-extensible thermal-adhesive bicomponent fiber that comprises a fiber-forming resin component and a thermal-adhesive resin component and is characterized in that the fiber-forming resin component comprises polyethylene terephthalate, that the thermal-adhesive resin component comprises a crystalline thermoplastic resin having a melting point lower by at least 20°C than that of the fiber-forming resin component, and that its breaking elongation is from 130 to 600 %, its 100 % elongation tensile strength is from 0.3 to 1.0 cN/dtex and its 120°C dry heat shrinkage is smaller than -1.0 %; and by a method for producing it.

Description

  The present invention relates to a self-extensible thermoadhesive conjugate fiber having a low modulus and having a self-extension property when thermally bonded, and exhibiting a soft texture when formed into a heat-bonded nonwoven fabric, and a method for producing the same.

  Thermal adhesive composite fibers represented by the core-sheath type thermal adhesive composite fiber with the thermal adhesive resin component as the sheath and the fiber-forming resin component as the core are used for the fiber web by the card method, airlaid method, wet papermaking method, etc. After forming, the heat-adhesive resin component is melted with a hot air dryer or hot roll to form an interfiber bond, so there is no need to use an adhesive with an organic solvent as a solvent, and there is little discharge of harmful substances to the environment. Moreover, the merit of the production speed improvement and the accompanying cost reduction is great, and it has been widely used mainly for fiber structures such as hard cotton and bed mats and nonwoven fabrics.

  Above all, for heat-bonded non-woven fabrics that are in direct contact with the skin, typified by sanitary materials such as paper diapers and sanitary napkins, the fabric has flexibility and draping properties, and has moderate bulkiness that is not paper-like. Nonwoven fabrics are being considered.

  In the heat roll method in which a part of the web is heat-pressed and softened or melted with an embossing roll, etc., the nonwoven fabric tends to bend at the boundary between the pressure-bonding area and the non-pressure-bonding area, and the drapeability is excellent. Since the pressure is flattened, the pressure-bonded portion is hardened and the bulkiness is lost, and the paper-like feel remains. On the other hand, in the air-through method in which hot air is blown over the entire web to soften or melt the intersection of the fibers, the hot air is passed while leaving the web bulk to some extent, so the resulting nonwoven fabric is bulky and has a region that becomes partially hard However, the surface touch is smooth, but on the other hand, irregular folds are easily generated with respect to bending, and drapeability is poor.

  As a solution to this problem, the orientation index of the heat-adhesive resin component is set to 25% or less and the orientation index of the fiber-forming resin component is set to 40% or more by a high-speed spinning method. A technology that achieves both draping properties, bulkiness, and nonwoven fabric strength by adhering a heat-fusible conjugate fiber having a low thermal shrinkage and a mixed cotton web of non-thermal adhesive fibers by an air-through method is disclosed. Yes. However, in the high speed spinning method, the current short fiber manufacturing process has a low yield in terms of both process stability and cost performance, and there are still many difficult issues for commercial production. Furthermore, when a heat-bonding nonwoven fabric composed solely of heat-adhesive conjugate fibers is formed, the number of bonding intersections in the nonwoven fabric increases, so there is a tendency to be inferior in drapability, and non-adhesive fibers are used for the purpose of reducing the number of bonding intersections. It was blended and the nonwoven fabric strength and soft texture were not necessarily at a sufficient level (see, for example, Patent Document 1).

Furthermore, an example in which the core component is polyethylene terephthalate (hereinafter referred to as PET) is not disclosed (see, for example, Patent Document 1). By using PET as the core component, the melting point of the core component can be sufficiently higher than that of the sheath component compared to the case where the core component is polypropylene (hereinafter referred to as PP), so that the thermal bond strength can be further improved. In addition, it has a high rigidity in terms of bulkiness and has the potential to obtain a bulkier nonwoven fabric. However, even if low-magnification drawing or just undrawn yarn as in Patent Document 1 is applied, the orientation of the core component The heat shrinkage was large due to insufficient crystallinity. Furthermore, when high-speed spinning as in Patent Document 1 is applied, the temperature of the sheath component must be increased in accordance with the melting temperature of the core component, and the yarn is severely broken due to deterioration of the sheath polymer and large spinning draft. There was an easy problem.
JP 2005-350836 A

  The present invention was made against the background of the above prior art, and its purpose is to produce a nonwoven fabric or fiber structure having polyethylene terephthalate as a fiber-forming resin component, high adhesive strength, bulky and good drapeability. It is an object of the present invention to provide a low-modulus self-extensible thermoadhesive conjugate fiber that enables this.

  As a result of intensive studies to solve the above problems, the present inventors have used a crystalline thermoplastic resin having a melting point 20 ° C. or more lower than that of PET as the thermoadhesive resin component, and spinning at 1300 m / min or less. The undrawn yarn taken up at a speed is drawn 1.05 to 1.3 times while being unheated or cooled in a refrigerant, and then the glass transition point of the thermoadhesive resin component and the glass transition point of the fiber-forming resin component. Low modulus self-extensible thermoadhesive conjugate fiber with PET as a fiber-forming resin component that satisfies high adhesive strength, sufficient bulkiness and drapeability by relaxing and shrinking at a temperature 10 ° C. or higher than both It came to invent.

  More specifically, the above-mentioned problem is a composite fiber composed of a fiber-forming resin component and a heat-adhesive resin component, the fiber-forming resin component is made of polyethylene terephthalate (PET), and the heat-adhesive resin component is a fiber forming component. It is made of a crystalline thermoplastic resin having a melting point 20 ° C. lower than that of the conductive resin component, has a breaking elongation of 130 to 600%, a 100% elongation stress of 0.3 to 1.0 cN / dtex, and a 120 ° C. dry heat shrinkage rate. Self-stretchable heat-adhesive conjugate fiber characterized by being less than -1% and unstretched yarn taken at a spinning speed of 1300 m / min or less are cold-drawn 1.05-1.3 times and then heat-bonded Solved by an invention by a method for producing a heat-adhesive conjugate fiber characterized in that it relaxes and shrinks at a temperature 10 ° C. higher than both the glass transition point of the adhesive resin component and the glass transition point of the fiber-forming resin component Rukoto can.

  The low-modulus self-extensible thermoadhesive conjugate fiber of the present invention has a soft texture based on the low modulus and self-extension of the heat-adhesive conjugate fiber itself, without reducing the bonding intersection with the non-thermo-adhesive fiber. Present, and can impart a high adhesive strength peculiar to a heat-bonded nonwoven fabric made of a heat-bondable conjugate fiber alone.

  Hereinafter, embodiments of the present invention will be described in detail. First, the present invention is a composite fiber composed of a fiber-forming resin component and a heat-adhesive resin component. The fiber-forming resin component is PET, and a crystalline thermoplastic resin having a melting point lower than PET by 20 ° C. or more is heat-adhesive. It is a low modulus self-extensible thermoadhesive conjugate fiber as a resin component. Here, if the difference in melting point between PET and the heat-adhesive resin component is less than 20 ° C., the fiber-forming resin component is also dissolved in the step of melting and adhering the heat-adhesive resin component, and a high-strength nonwoven fabric or fiber structure is obtained. It is not preferable because it cannot be done. For this composite fiber, an undrawn yarn is obtained at a spinning speed of 1300 m / min or less using a known composite fiber melting method or die, and then cold drawn to 1.05 to 1.3 times. Further, the glass transition of PET By relaxing and shrinking at a temperature 10 ° C. or more higher than both the point (hereinafter referred to as Tg) and Tg of the thermoplastic crystalline resin constituting the thermoadhesive resin component, preferably 20 ° C. or higher can get. Specifically, the temperature higher than both the Tg of PET and the Tg of the thermoplastic crystalline resin of the thermoadhesive resin component is often higher than the Tg of PET (about 70 ° C.), and therefore 80 Relaxing shrinkage is performed at a temperature of preferably at least 85 ° C. More preferably, it is 100 degreeC or more. In the present invention, since the melting point of the crystalline thermoplastic resin constituting the thermoadhesive resin component is 20 ° C. or more lower than the melting point of PET as described above, the Tg of the thermoplastic crystalline resin constituting the thermoadhesive resin component is as follows. This is because is often lower than the Tg of PET. If the temperature of the relaxation / shrinkage treatment is lower than this range, the shrinkage rate at the time of thermal bonding of the composite fiber is not preferable. The relaxation shrinkage may be performed by passing the tow through hot air in a state where no tension is applied after stretching, or by overfeeding at 0.5 to 0.85 times so that no tension is applied in warm water. Good.

  Residual strain imparted during spinning of the original unstretched yarn shrinks in the fiber axis direction in a tension-free state, and the crystals formed in the unstretched yarn are tilted in a random direction from the fiber axis, and further crystallized by applying temperature. As the thickness increases, the fibers appear to be stretched, so-called self-stretching. This is a phenomenon that becomes more prominent in high-speed spinning at 2000 m / min or more, but according to the study of the present inventor, in the case of an undrawn yarn of 1300 m / min or less, it is stretched at a slight magnification and then relaxed. It has been found that the self-extension rate can be further increased by the method of contraction, and the present invention has been achieved. When a core-sheath composite fiber having a core of PET (inherent viscosity: IV = 0.64 dL / g) and a sheath of high-density polyethylene (MFR = 20 g / 10 min) is drawn at a spinning speed of 1150 m / min, the draw ratio is 1. When it exceeds 0 times, the self-elongation rate increases and reaches a maximum at a draw ratio of 1.2 times. Since self-stretching is how the crystal orientation is random with respect to the fiber axis before crystal thickening, the fiber may be greatly shrunk before crystallization. If a lower drawing temperature, that is, a cold drawing of 1.05 to 1.3 times, is applied than the heat drawing of a plate heater or the like, the residual strain of the amorphous part can be increased while suppressing oriented crystallization due to drawing. It is possible and suitable. Here, “cold stretching” includes not only stretching at room temperature but also stretching in an atmosphere that is positively cooled to a temperature below room temperature. Specific examples include stretching in a non-heated state at room temperature or in a refrigerant cooled to room temperature or lower, and more specifically, cold stretching in air, stretching in a cold water bath, and the like. As described above, in addition to air and water, the refrigerant is inert with respect to the fiber-forming resin component and the heat-adhesive resin component forming the composite fiber, and does not swell or dissolve, such as nitrogen, Gases such as carbon dioxide, and liquids such as various oils that are not soluble in polyester can be appropriately selected. The temperature of the refrigerant during cold stretching can be 0 to 30 ° C, preferably 10 to 25 ° C.

  Therefore, in order for the self-elongation rate at 120 ° C. to exceed 1.0% (ie, the dry heat shrinkage rate at 120 ° C. is less than −1%) and the tensile strength at 100% elongation to be 1.0 cN / dtex or less, The draw ratio needs to be in the range of 1.05 to 1.3. When the draw ratio is less than 1.05, the tensile strength at 100% elongation is 1.0 cN / dtex or less, but the self-elongation rate is less than 1.0%, and the original purpose cannot be satisfied. When the draw ratio exceeds 1.3 times, the tensile strength at 100% elongation exceeds 1.0 cN / dtex. And the target drape property cannot be achieved in the heat bonding nonwoven fabric which consists of this 100% fiber web. The lower the stretching temperature, the better. When cold water is used as the refrigerant, it is particularly preferably 25 ° C. or lower. By gradually heating the heat generated during stretching, crystallization accompanying the orientation and heat generation is suppressed, and this contributes to increasing heat shrinkage. As described above, in the composite fiber of the present invention, the 100% elongation stress needs to be 0.3 to 1.0 cN / dtex. If the 100% elongation stress is less than 0.3 cN / dtex, the nonwoven fabric has insufficient strength and the texture of the nonwoven fabric tends to deteriorate, and if it exceeds 1.0 cN / dtex, it tends to be inferior in self-extension and flexibility (draping). It is not preferable.

  The spinning speed needs to be 1300 m / min or less, preferably 1200 m / min or less, more preferably 1100 m / min or less. When it exceeds 1300 m / min, the orientation of the undrawn yarn increases, but the effect of increasing the self-elongation rate by the low-magnification drawing of the present invention is reduced.

  The form of the low-modulus self-extensible thermoadhesive conjugate fiber of the present invention is a fiber-forming resin component even if it is a conjugate fiber in which a fiber-forming resin component and a heat-adhesive resin component are bonded in a so-called side-by-side manner. May be a core-sheath type composite fiber having a core component and a heat-adhesive resin component as a sheath component. However, a core-sheath type composite in which the fiber-forming resin component is the core component and the heat-adhesive resin component is the sheath component in that the heat-adhesive resin component can be arranged in any direction perpendicular to the fiber axis direction. It is preferably a fiber. Examples of the core-sheath type composite fiber include concentric core-sheath type composite fiber and eccentric core-sheath type composite fiber.

  For the thermoadhesive resin component (sheath component), it is necessary to select a crystalline thermoplastic resin. In the case of an amorphous thermoplastic resin, the molecular chains that are oriented during spinning are greatly shrunk as they become non-oriented simultaneously with melting. Preferable examples of the crystalline thermoplastic resin include polyolefin resins and crystalline copolyesters.

  Examples of the polyolefin resin include polyolefins such as polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, or crystalline propylene copolymer composed of propylene and other α-olefins, Or an α-olefin such as ethylene, propylene, butene-1, or pentene-1, and an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, or hymic acid Or modified polyolefins which consist of a copolymer with at least 1 sort of comonomers, such as unsaturated compounds which have polar groups, such as these esters or acid anhydrides, etc. are mentioned.

  Examples of crystalline copolyesters include, as the acid component, the main dicarboxylic acid component being terephthalic acid or an ester-forming derivative thereof, and the main diol component being ethylene glycol, diethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol. To an alkylene terephthalate obtained by a combination of 1 to 3 aromatic dicarboxylic acids such as isophthalic acid, naphthalene-2,6-dicarboxylic acid and 5-sulfoisophthalate, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid , Alicyclic dicarboxylic acids such as cyclohexamethylene dicarboxylic acid, ε-hydroxycarboxylic acid, ω-hydroxycarboxylic acid, etc. In addition to the above examples, the diol component is a fat such as polyethylene glycol, polytetramethylene glycol, etc. Examples include those obtained by copolymerizing an aliphatic diol, an alicyclic diol such as cyclohexamethylene dimethanol and the like so as to exhibit a target melting point. The copolymerization rate is desirably variously adjusted by the copolymerization component so as to exhibit the target melting point, but is preferably 5 to 50 mol%. When the fiber-forming resin component is PET, the heat-adhesive resin component in the present invention may be in the form of a polymer blend of two or more crystalline thermoplastic resins whose melting point is 20 ° C. or lower than PET, A crystalline thermoplastic resin having a melting point difference of less than 20 ° C. with respect to an amorphous thermoplastic resin or PET may be contained within a range that does not significantly impair adhesion and low heat shrinkability.

  The elongation at break of the low modulus self-extensible thermoadhesive conjugate fiber needs to be in the range of 130 to 600%, and preferably in the range of 170 to 450%. If the elongation at break is less than 130%, the orientation of the thermal adhesive component is high, so that the adhesiveness is inferior and the strength of the nonwoven fabric is reduced. On the other hand, if it exceeds 600%, the fiber strength becomes substantially too small to increase the strength of the heat-bonded nonwoven fabric.

  The method for controlling the elongation at break within the range of 130 to 600% depends on the type of polymer and the melt viscosity, but includes the hole diameter of the nozzle that discharges the polymer and the spinning speed. large. In the present invention, the elongation at break within the above range is controlled depending on the type and combination of polymers, but the spinning speed is preferably in the range of 100 to 1300 m / min. The elongation at break can be increased by decreasing the elongation and decreasing the spinning speed.

  The low modulus self-extensible thermoadhesive conjugate fiber of the present invention has a feature of 120 ° C. dry heat shrinkage of less than −1%. Since the fibers self-extend before heat bonding, the thickness in the thickness direction appears, and the fibers with low modulus are oriented in the vertical direction, so when considering compression in the thickness direction, a soft texture Thus, when used as a sanitary material surface material, the feeling of pressure in the direction perpendicular to the skin is reduced, and the drape is also improved.

  The fiber cross section is preferably a concentric core-sheath cross section or an eccentric core-sheath cross section. In the side-by-side type, the effect aimed by the present invention can be somewhat reduced in the direction in which the shrinkage is large in the web state due to the development of three-dimensional crimp and the adhesive strength is also reduced. Further, it may be a solid fiber or a hollow fiber, and is not limited to a round cross section, but is an elliptical cross section, a multileaf cross section such as a 3-8 leaf cross section, or a polygon such as a 3-8 octagon. An irregular cross section such as a cross section may be used.

  The fineness may be selected according to the purpose and is not particularly limited, but is generally used in a range of about 0.01 to 500 dtex. This fineness range can be achieved by setting the diameter of the die through which the resin is discharged during spinning to a predetermined range.

  The composite ratio of the fiber-forming resin component and the heat-adhesive resin component is not particularly limited, but is selected according to the requirements for the strength, bulk, and heat shrinkage of the target nonwoven fabric or fiber structure. The ratio of the fiber-forming resin component / the heat-adhesive resin component is preferably about 10/90 to 90/10 by weight.

  The form of the fiber can take any form such as multifilament, monofilament, staple fiber, chop, and tow depending on the purpose of use. When the heat-adhesive conjugate fiber of the present invention is used as a staple fiber that requires a carding process, a suitable number of crimps is imparted to the conjugate fiber in order to impart good card passage properties. It is desirable. The heat-adhesive conjugate fiber of the present invention is particularly effective in improving the drapeability in a random nonwoven fabric having a fiber structure. Therefore, the self-extensible thermoadhesive conjugate fiber of the present invention can produce a non-woven fabric composed of it alone. You may manufacture a nonwoven fabric by mixing with another fiber as needed. As a method for obtaining a nonwoven fabric, a cantilever value of 10 cm is obtained by forming a web by the card method, air laying method, wet papermaking method, etc., and applying a predetermined heat in a hot air dryer or an embossing roll to thermally bond it. The following flexible heat-bonding nonwoven fabric excellent in drapeability can be obtained.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In addition, each item in an Example was measured with the following method.

(1) Intrinsic viscosity (IV)
A fixed amount of the polymer was weighed and dissolved in o-chlorophenol at a concentration of 0.012 g / ml, and then determined at 35 ° C. according to a conventional method.

(2) Melt flow rate (MFR)
It measured according to JIS K-7210 condition 4 (190 degreeC, 21.18N). The melt flow rate is a value measured using a pellet before melt spinning as a sample.

(3) Melting point (Tm), glass transition point (Tg)
A thermal analyst 2200 manufactured by TA Instrument Japan Co., Ltd. was used, and the temperature was measured at a temperature rising rate of 20 ° C./min.

(4) Fineness Measured by the method described in JIS L-1015: 2005 8.5.1 Method A.

(5) Strength / Elongation, 100% Extension Stress Measured by the method described in JIS L-1015: 2005 8.7.1 method. Since the fiber of the present invention tends to vary in the strength and elongation due to the efficiency of the constant length heat treatment, it is necessary to increase the number of measurement points when measuring with a single yarn. Since the number of measurement points is preferably 50 or more, here, the number of measurement points is defined as 50, which is defined as the average value. Further, since the stress at the time of 100% elongation of the load-strain curve at the time of measuring the strength and elongation is read, 100% elongation stress can be measured.

(6) Number of crimps and crimp rate Measured by the method described in JIS L-1015: 2005 8.12.1 to 8.12.2.

(7) 120 degreeC dry heat shrinkage rate It implemented at 120 degreeC in JIS L-1015: 2005 8.15 b).

(8) Shrinkage ratio of web area Hot air dryer (Satake Chemical Machinery Co., Ltd.) cut a card web with a basis weight of 30 g / m ² made of 100% heat-adhesive composite short fiber cut to a fiber length of 51 mm into a 25 cm square and maintained at 150 ° C. It was heat-bonded for 2 minutes in a hot air circulating thermostatic dryer manufactured by Kogyo Co., Ltd .: 41-S4). The area A1 is calculated by measuring and multiplying the vertical and horizontal dimensions of the web after heat bonding, and the area shrinkage rate is obtained by the following equation.
Area shrinkage rate (%) = [(A ₀ −A ₁ ) / A ₀ ] × 100 A ₀ = 625 (cm ² )

(9) Nonwoven fabric strong (adhesive strength)
The heat-bonded nonwoven fabric (thickness 5 mm) obtained by the above-described method was cut into a test piece having a width of 5 cm and a length of 20 cm in the machine direction (flow direction in the process of manufacturing the nonwoven fabric), with a gripping interval of 10 cm and an elongation rate of 20 cm / min It was measured. The adhesive strength was a value obtained by dividing the tensile breaking force by the weight of the test piece.

(10) Cantilever The thermobonding nonwoven fabric (thickness 5 mm) obtained by the above method was cut into a test piece having a width of 2.5 cm and a length of 25 cm in the machine direction, and measured by the method of JIS L-1086: 1983 6.12.1. did. Shows the cantilever value in the machine direction only.

[Example 1]
Polyethylene terephthalate (PET) with IV = 0.64 dL / g, Tg = 70 ° C., Tm = 256 ° C. for the core component (fiber-forming resin component), MFR = 20 g / 10 min for the sheath component (thermal adhesive resin component), After using high density polyethylene (HDPE) with Tm = 131 ° C. (Tg is less than 0 ° C.) and melting at 290 ° C. and 250 ° C., respectively, using a known core-sheath composite fiber die, core: sheath = 50 A composite fiber was formed so as to have a weight ratio of 50 and spun at a discharge rate of 0.70 g / min / hole and a spinning speed of 1150 m / min to obtain an undrawn yarn. After cold drawing at 1.2 times, the yarn was immersed in an aqueous solution of an oil agent consisting of potassium lauryl phosphate / polyoxyethylene-modified silicon = 80/20, and then 11 pieces / piece using a stuffing box. A 25 mm mechanical crimp was imparted, relaxation shrinkage and drying were performed with hot air at 110 ° C., which is 40 ° C. higher than the glass transition point of the core component, and the fiber length was cut to 51 mm. The single yarn fineness was 6.4 dtex, strength 0.76 cN / dtex, elongation 442%, 100% elongation stress 0.37 cN / dtex, 120 ° C. dry heat shrinkage −2.6%. The shrinkage ratio of the web area composed of 100% of this heat-adhesive conjugate fiber was -7.5%, the nonwoven fabric strength was 15.1 kg / g, and the cantilever value was 8.50 cm.

[Comparative Example 1]
The same operation as in Example 1 was performed except that the undrawn yarn described above was stretched 2.5 times in warm water at 70 ° C. and 1.2 times in warm water at 90 ° C. The single yarn fineness was 2.6 dtex, the strength was 2.49 cN / dtex, the elongation was 37.1%, and the 120 ° C. dry heat shrinkage was 2.5%. The shrinkage ratio of the web made of 100% heat-adhesive conjugate fiber was 5%, the nonwoven fabric strength was 20.5 kg / g, and the cantilever value was 12.90 cm.

[Comparative Example 2]
A fiber was obtained in the same manner as in Example 1 except that the drawing treatment was not performed. The single yarn fineness was 6.47 dtex, strength 0.60 cN / dtex, elongation 460.3%, 100% elongation stress 0.37 cN / dtex, 120 ° C. dry heat shrinkage −0.7%. The web area shrinkage rate of this heat-adhesive conjugate fiber 100% was -1.45%, the nonwoven fabric strength was 14.5 kg / g, and the cantilever value was 7.90 cm.

[Example 2]
The procedure was the same as Example 1 except that the draw ratio was 1.1 times. The single yarn fineness was 6.41 dtex, strength 0.65 cN / dtex, elongation 424.1%, 100% elongation stress 0.41 cN / dtex, and 120 ° C. dry heat shrinkage −1.9%. The web area shrinkage percentage of this heat-adhesive conjugate fiber 100% was -5.6%, the nonwoven fabric strength was 16.5 kg / g, and the cantilever value was 8.10 cm.

[Example 3]
The procedure was the same as Example 1 except that the draw ratio was 1.3. The single yarn fineness was 6.22 dtex, strength 0.72 cN / dtex, elongation 381.8%, 100% elongation stress 0.46 cN / dtex, 120 ° C. dry heat shrinkage −2.0%. The shrinkage ratio of the web area composed of 100% of this heat-adhesive conjugate fiber was -6.1%, the nonwoven fabric strength was 17.1 kg / g, and the cantilever value was 8.90 cm.

[Comparative Example 3]
The procedure was the same as Example 1 except that the draw ratio was 1.4. The single yarn fineness was 6.14 dtex, the strength was 0.75 cN / dtex, the elongation was 346.8%, the 100% elongation stress was 0.53 cN / dtex, and the dry heat shrinkage at 120 ° C. was −0.6%. The web area shrinkage percentage of this heat-adhesive conjugate fiber 100% was -1.8%, the nonwoven fabric strength was 18.4 kg / g, and the cantilever value was 10.1 cm.

[Example 4]
The same procedure as in Example 1 was performed except that the stretching was performed while cooling in a water bath controlled at a water temperature of 20 ° C. The single yarn fineness was 6.52 dtex, strength 0.65 cN / dtex, elongation 459.3%, 100% elongation stress 0.39 cN / dtex, and 120 ° C. dry heat shrinkage -3.2%. The shrinkage ratio of the web area composed of 100% of this heat-adhesive conjugate fiber was -9.5%, the nonwoven fabric strength was 15.3 kg / g, and the cantilever value was 8.13 cm.

[Example 5]
The relaxation heat treatment was performed in the same manner as in Example 1 except that 0.7 times overfeed was applied in a warm water bath at 95 ° C. and no subsequent hot air drying was performed. The single yarn fineness was 6.58 dtex, strength 0.68 cN / dtex, elongation 443.3%, 100% elongation stress 0.41 cN / dtex, 120 ° C. dry heat shrinkage −3.9%. The shrinkage ratio of the web made of 100% heat-adhesive conjugate fiber was -11.4%, the nonwoven fabric strength was 14.9 kg / g, and the cantilever value was 8.90 cm.

[Example 6]
Polyethylene terephthalate (PET) with IV = 0.64 dL / g, Tg = 70 ° C., Tm = 256 ° C. for the core component (fiber-forming resin component), MFR = 40 g / 10 min for the sheath component (thermal adhesive resin component), Using Tm = 152 ° C. and Tg = 43 ° C. crystalline copolyester (co-PET-1: isophthalic acid 20 mol% -tetramethylene glycol 50 mol% copolymer polyethylene terephthalate), the temperatures become 290 ° C. and 255 ° C., respectively. After melting as above, a composite fiber is formed using a known core-sheath composite fiber die so as to have a weight ratio of core: sheath = 50: 50, discharge amount 0.71 g / min / hole, spinning speed 1250 m. Spinning at / min, an undrawn yarn was obtained. This was cold-drawn at 1.2 times, and the yarn was immersed in an aqueous solution of an oil agent composed of potassium lauryl phosphate / polyoxyethylene-modified silicon = 80/20, and then 11 pieces / 25 mm using an indentation type crimper. After mechanical crimping and drying and relaxation heat treatment in hot air at 90 ° C., the fiber length was cut to 51 mm. The single yarn fineness measured with the tow before cutting was 5.7 dtex, strength 0.94 cN / dtex, elongation 392%, 100% elongation stress 0.35 cN / dtex, 120 ° C. dry heat shrinkage −3.8%. It was. The shrinkage ratio of the web made of 100% heat-adhesive conjugate fiber (however, the heat-bonding temperature was changed to 180 ° C.) was −11.2%, the nonwoven fabric strength was 12.3 kg / g, and the cantilever value was 8.30 cm. It was.

  The low-modulus self-extensible thermoadhesive conjugate fiber of the present invention uses PET as a fiber-forming resin component and has a low spinning speed, so that it has extremely low spun yarn and has high adhesiveness and drapeability. The bulky nonwoven fabric which can be improved and has a good texture can be obtained.

Claims (8)

  A composite fiber comprising a fiber-forming resin component and a heat-adhesive resin component, wherein the fiber-forming resin component is made of polyethylene terephthalate, and the heat-adhesive resin component has a melting point that is 20 ° C. lower than the fiber-forming resin component Self-elongation characterized by comprising a thermoplastic resin, having a breaking elongation of 130 to 600%, a 100% elongation stress of 0.3 to 1.0 cN / dtex, and a 120 ° C. dry heat shrinkage ratio of less than −1% Heat-adhesive composite fiber.   The heat-adhesive conjugate fiber according to claim 1, wherein the fiber-forming resin component is a core-sheath conjugate fiber in which the core component is a core component and the heat-adhesive resin component is a sheath component.   The heat-adhesive conjugate fiber according to claim 1, wherein the heat-adhesive resin component is a polyolefin resin.   The heat-adhesive conjugate fiber according to any one of claims 1 to 2, wherein the heat-adhesive resin component is a crystalline copolyester.   After cold drawing the undrawn yarn taken at a spinning speed of 1300 m / min or less to 1.05 to 1.3 times, both from the glass transition point of the heat-adhesive resin component and the glass transition point of the fiber-forming resin component The method for producing a thermoadhesive conjugate fiber according to any one of claims 1 to 4, wherein the shrinkage and shrinkage are performed at a temperature higher by 10 ° C or more.   6. The method for producing a thermoadhesive conjugate fiber according to claim 5, wherein the relaxation shrinkage is performed in hot air.   6. The method for producing a thermoadhesive conjugate fiber according to claim 5, wherein the relaxation contraction is performed in warm water.   A thermobonding nonwoven fabric having a cantilever value of 10 cm or less, comprising the self-extensible thermoadhesive conjugate fiber alone according to any one of claims 1 to 4.