JP4312066B2 - Heat-resistant polylactic acid-based long fiber nonwoven fabric - Google Patents

Description

  The present invention relates to a heat-resistant polylactic acid-based long-fiber nonwoven fabric made of a plant-derived polymer having excellent heat resistance.

  In recent years, synthetic fibers using petroleum as a raw material have a large amount of heat generated during incineration, and therefore need to be reviewed from the viewpoint of protecting the natural environment. In contrast, fibers made of aliphatic polyester that biodegrades in nature have been developed and are expected to contribute to environmental protection. Among aliphatic polyesters, polylactic acid polymers are expected to be used in a wide range of fields because they have a relatively high melting point. In addition, polylactic acid polymers have the best balance of mechanical properties, heat resistance, and cost among biodegradable polymers. And development of the fiber using this is performed at a rapid pitch.

  However, the most promising polylactic acid polymer also has a problem of poor high-temperature mechanical properties. Here, poor high temperature mechanical properties indicate that the polymer rapidly softens when the glass transition temperature (Tg) of the polylactic acid polymer exceeds 60 ° C. Actually, when a tensile test of a long-fiber non-woven fabric made of a polylactic acid polymer is performed at a different temperature, it has been found that the strength of the long-fiber non-woven fabric rapidly decreases at 70 ° C. or higher.

  A long-fiber nonwoven fabric made of a polylactic acid-based polymer is inferior in mechanical properties at high temperatures as described above, so there is no problem when used in a normal atmosphere, but deformation and sag occur in a high-temperature atmosphere. For this reason, for example, it is unsuitable for the interior material for motor vehicles exposed to the sun. In addition, for example, when a polylactic acid-based long fiber nonwoven fabric is used for a molding carpet, when it is molded at a molding temperature such as 130 ° C. or 140 ° C., the strength and elongation of the nonwoven fabric at high temperatures are low. There is a problem that the carpet base fabric is torn at the portion where the moldability is deteriorated, particularly in the deep drawing.

In order to compensate for the disadvantages of the above polylactic acid polymer, (1) a method of blending polyethylene terephthalate copolymerized with alkylene diol or bisphenol A derivative with polylactic acid, (2) polyethylene terephthalate copolymerized with long chain carboxylic acid Have been proposed, such as a method of blending lactic acid with polylactic acid, and (3) a method of utilizing an oriented crystallization structure by high-speed spinning. Among these, a method using an oriented crystallization structure by high speed spinning will be described below. For example, homopoly L lactic acid having a weight average molecular weight of 100,000 to 300,000 is discharged from the die at a spinning temperature of 210 to 250 ° C., and the yarn is cooled and solidified by cooling air. Then, the oil agent for fibers is applied, taken up at high speed, and wound up as it is. At this time, the high-speed take-up speed is determined so that the crystal size in the (200) plane direction of the wound polylactic acid fiber is 6 nm or more. Then, the polylactic acid fiber oriented and crystallized by this high-speed spinning is further stretched at a stretching temperature of 100 ° C. or higher and is heat-set (Patent Document 1).
JP 2003-41433 A

  This invention makes it a subject to obtain the new method for providing heat resistance to the long-fiber nonwoven fabric formed with a polylactic acid-type polymer.

  As a result of intensive studies to solve the above problems, the present inventors have paid attention to the constituent polymer of the nonwoven fabric, and have prepared a copolymer containing a polylactic acid polymer, a terephthalic acid component, an ethylene glycol component and a butanediol component. Finding that heat resistance can be imparted to long-fiber non-woven fabrics formed from polylactic acid polymers by using composite polyester and a composite long fiber that adopts a specific composite form The present invention has been reached.

  That is, the heat-resistant polylactic acid-based long fiber nonwoven fabric of the present invention is a composite long fiber comprising a polylactic acid-based polymer and a copolymer polyester containing a terephthalic acid component, an ethylene glycol component, and a butanediol component as constituent components. The composite form of the composite long fiber is a core-sheath composite type in which a polylactic acid polymer forms a core and a copolymer polyester forms a sheath, or a polylactic acid The gist of the invention is that the polymer is a multi-leaf composite type in which a core portion is formed and the copolymer polyester is formed with a plurality of protruding leaf portions so as to surround the outer periphery of the core portion.

  The heat-resistant polylactic acid-based long-fiber nonwoven fabric of the present invention is a polymer constituting a composite long fiber, wherein the polylactic acid-based polymer has a melting point of 150 ° C. or higher and the copolymer polyester has a melting point of the polylactic acid-based polymer. When the melting point is higher than the melting point, the melting point difference is preferably 50 ° C. or less.

  The heat-resistant polylactic acid-based non-woven fabric of the present invention is preferably integrated by having a partial thermocompression bonding portion, and the composite ratio (mass of polylactic acid-based polymer and copolymerized polyester). Ratio) is preferably polylactic acid polymer / copolyester = 3/1 to 1/1.

  Further, the heat-resistant polylactic acid-based composite long fiber of the present invention comprises a polylactic acid-based polymer and a copolymer polyester containing a terephthalic acid component, an ethylene glycol component, and a butanediol component as constituent components. The polymer forms a core and the copolymer polyester is a core-sheath composite type long fiber that forms a sheath, or the polylactic acid-based polymer forms the core, and the copolymer polyester has a core The gist of the present invention is a multileaf composite long fiber in which a plurality of protruding leaf portions are formed so as to surround the outer periphery.

  The heat-resistant polylactic acid composite long fiber of the present invention has a melting point difference when the melting point of the polylactic acid polymer is 150 ° C. or higher and the melting point of the copolymer polyester is higher than the melting point of the polylactic acid polymer. It is suitable that it is 50 degrees C or less.

  In addition, the heat-resistant polylactic acid-based composite long fiber of the present invention has a composite ratio (mass ratio) of the polylactic acid-based polymer and the copolymerized polyester: polylactic acid-based polymer / copolymerized polyester = 3/1 to 1 / 1 is preferred.

  The heat-resistant polylactic acid-based non-woven fabric of the present invention is made of a plant-derived polymer and has a biodegradable polylactic acid-based polymer inferior in mechanical properties at high temperatures. Because it is composed of composite fibers that are almost covered with polymerized polyester, it can be made into a form that hardly transfers heat from the outside to the polylactic acid-based polymer, and has good heat resistance when placed in a high-temperature atmosphere. It becomes a nonwoven fabric. And since the heat resistance in high temperature atmosphere is favorable, it can be used conveniently for the use as which heat resistance is requested | required, such as a vehicle interior material.

  Similarly, the heat-resistant polylactic acid-based composite long fiber of the present invention is made of a plant-derived polymer and has a biodegradability but is inferior in mechanical properties at high temperatures. Since it is generally coated with a superior special copolyester, the polylactic acid polymer can be made in a form that is difficult to transfer heat from the outside, and has good heat resistance when placed in a high temperature atmosphere Long fiber.

  The heat-resistant polylactic acid-based long fiber nonwoven fabric of the present invention is a composite long fiber deposited with a polylactic acid-based polymer and a copolyester containing a terephthalic acid component, an ethylene glycol component, and a butanediol component. This is a non-woven fabric.

  The heat-resistant polylactic acid-based long fiber of the present invention is a composite long fiber composed of a polylactic acid-based polymer and a copolymerized polyester containing a terephthalic acid component, an ethylene glycol component, and a butanediol component. .

First, the polylactic acid polymer will be described.
The polylactic acid-based polymer in the present invention includes poly-D-lactic acid, poly-L-lactic acid, a copolymer of D-lactic acid and L-lactic acid, and a copolymer of D-lactic acid and hydroxycarboxylic acid. And a polymer selected from the group consisting of a copolymer, a copolymer of L-lactic acid and hydroxycarboxylic acid, and a copolymer of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, or a blend thereof. . Examples of the hydroxycarboxylic acid used for copolymerization include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, and the like. And glycolic acid are preferable from the viewpoint of decomposition performance and cost reduction.

  In the present invention, the polylactic acid polymer is used, and a polymer having a melting point of 150 ° C. or higher or a blend of a plurality of polymers having a melting point of 150 ° C. or higher is used. When the melting point of the polylactic acid-based polymer is 150 ° C. or higher, since it has high crystallinity, shrinkage during heat treatment is less likely to occur, and heat treatment can be performed stably. The resulting long fiber nonwoven fabric is excellent in heat resistance.

  The melting point of poly-L-lactic acid and poly-D-lactic acid, which are homopolymers of polylactic acid, is about 180 ° C. When using a copolymer instead of a homopolymer as the polylactic acid-based polymer, the copolymerization ratio of the monomer components is determined so that the melting point of the copolymer is 150 ° C. or higher. In the case of a copolymer of L-lactic acid and D-lactic acid, the copolymerization ratio of L-lactic acid and D-lactic acid is (L-lactic acid) / (D-lactic acid) = 5 / 95 to 0/100 or (L-lactic acid) / (D-lactic acid) = 95/5 to 100/0 is used. When the copolymerization ratio is out of the above range, the melting point of the copolymer becomes less than 150 ° C., the amorphousness becomes high, and the object of the present invention cannot be achieved.

  On the other hand, as the copolyester, those containing a terephthalic acid component, an ethylene glycol component and a butanediol component are used. Since the copolyester having this as a component is crystalline, it has a clear crystal melting point (shows a clear melting point peak when a melting endothermic curve is drawn). For this reason, when the heat | fever is provided, the fiber obtained has a high crystallinity, Therefore A heat shrink does not arise easily. Therefore, when a thermal bonding treatment is applied to a web or nonwoven fabric made of this fiber, the fiber does not shrink and the dimensional stability is good. Further, since there is little decrease in the strength and elongation of the fiber even in a high temperature atmosphere, the nonwoven fabric made of this fiber has good dimensional stability, little decrease in mechanical strength, and can maintain stable quality.

  Moreover, the copolyester which further copolymerized (epsilon) -caprolactone to the alkylene terephthalate unit containing the said 3 component may be sufficient. By copolymerizing ε-caprolactone, the melting point can be adjusted without impairing the crystallinity. In addition, the ε-caprolactone unit in the polyester may be randomly copolymerized with other structural units or may be block copolymerized.

  The melting point of the copolyester is preferably 140 ° C. or higher, more preferably 180 ° C. or higher in consideration of use in a high temperature atmosphere. When the melting point of the copolyester is higher than the melting point of the polylactic acid polymer to be combined, the difference in melting point is 50 ° C. or less. When the melting point difference exceeds 50 ° C., the polylactic acid polymer is decomposed during melt spinning.

The copolyester preferably has a glass transition temperature (Tg) of 20 to 80 ° C. and a crystallization temperature (Tc) of 90 to 130 ° C.
If the Tg of the copolyester is less than 20 ° C., adhesion occurs between the single yarns during melt spinning, resulting in poor yarn production. Further, when Tg exceeds 80 ° C., it is necessary to stretch at a high temperature in the spinning process, but it is impossible to stretch at such a high temperature in the spunbond method in which the filament is cooled and stretched at once.

  In addition, when the Tc of the copolyester is less than 90 ° C., when the spunbond method is applied, the temperature from the thermocompression bonding temperature to Tc is too high based on the fact that the thermobonding process melts and fixes below the Tc temperature. Since sheet delamination occurs due to the sheet tension during the process. On the other hand, when Tc exceeds 130 ° C., the melting point (Tm) also increases in parallel, and therefore, it is necessary to perform melt spinning at 230 ° C. or higher. As a result, the polylactic acid polymer is decomposed when melted, It is not preferable.

  The copolyester is selected so as to have the above physical properties, and can be obtained by polymerizing a terephthalic acid component, an ethylene glycol component, and a butanediol component.

  Various additives such as matting agents, pigments, crystal nucleating agents and the like are added to the polymers used for the polylactic acid-based polymer and the copolyester, as necessary, so long as the effects of the present invention are not impaired. Also good. In particular, it is preferable to add a crystal nucleating agent such as talc, titanium oxide, calcium carbonate, and magnesium carbonate in order to prevent fusion (blocking) between yarns in the spinning / cooling step. This crystal nucleating agent is preferably used in the range of 0.1 to 3% by mass.

  The composite form of the composite long fiber is a core-sheath composite type in which a polylactic acid polymer forms a core and a copolymer polyester forms a sheath, or a polylactic acid polymer forms a core. The copolyester is a multi-leaf composite type in which a plurality of protruding leaf portions are formed so as to surround the outer periphery of the core portion.

  By placing the polylactic acid polymer in the core and covering the core with a sheath of the copolymer polyester, or surrounding the core with a plurality of protruding leaves of the copolymer polyester, that is, polylactic acid By disposing the polymer at the center of the fiber cross section, it is possible to make it difficult to transfer heat from the outside to the polylactic acid polymer. Thereby, the fault that the mechanical property of polylactic acid under high temperature is bad can be covered. It is also possible to overcome another drawback of polylactic acid, which is inferior in hydrolysis resistance.

1 and 2 are schematic views showing examples of cross sections of multi-leaf composite fibers in the present invention.
Each of FIGS. 1 and 2 is a multi-leaf type composite fiber 3 in which a polylactic acid-based polymer forms a core portion 1 and a copolyester forms a leaf portion 2. In FIG. 1, each leaf portion 2 is divided by the core portion 1, and a part of the polylactic acid in the core portion 1 is exposed on the fiber surface. In FIG. 2, the leaf portion 2 is not divided by the core portion 1 but is formed in a series of rings, and covers the core portion 1.

  In such a configuration, since the leaf portion 2 protrudes in a protruding shape, the degree of deformity becomes high, so that in the fiber production process, the melt-spun fiber is easy to cool and the spreadability is improved. Also play.

  The number of leaf portions 2 in the multileaf composite type is preferably 3 to 10. When the number of the protruding leaf portions 2 is small, the polylactic acid polymer as the core portion 1 is easily exposed on the surface of the fiber 3 depending on the size of each leaf portion 2, and the exposed ratio becomes large. Thus, the heat resistance that is the object of the present invention tends to be difficult to achieve. In addition, when the number of the leaf parts 2 increases, the leaf parts 2 come into contact with each other, so that a so-called core-sheath-type cross-sectional shape that completely covers the core part 1 tends to be formed, and the degree of deformity tends to decrease.

  Moreover, it is preferable that the arrangement | positioning form of the protrusion-shaped leaf part 2 is located at equal intervals on the outer periphery of a fiber cross section, respectively. When the leaf portions 2 are respectively offset from the outer circumference of the fiber cross section, the spun yarn generates kneeling in the spinning process, and the adhesive strength at each bonding point is difficult to be uniform at the time of thermal bonding, Strong spots are likely to occur in the resulting nonwoven fabric.

  The composite ratio (mass ratio) between the polylactic acid polymer and the copolymer polyester in the composite long fiber is preferably polylactic acid polymer / copolymer polyester = 3/1 to 1/1. If the ratio of polylactic acid polymer / copolyester exceeds 3/1 and the amount of polylactic acid polymer is large, the ratio of the polylactic acid polymer in the fiber cross section becomes too large, so that the high temperature atmosphere The result is inferior mechanical properties of the long-fiber nonwoven fabric below. On the other hand, if the polylactic acid polymer is so small that the ratio of polylactic acid polymer / copolyester is less than 1/1, a plant-derived resin (polyester) This is not preferable because it is deviated from the purpose of obtaining an environment-friendly long-fiber nonwoven fabric using a lactic acid polymer.

  The single yarn fineness of the composite continuous fiber in the present invention is preferably about 0.5 dtex to 11 dtex. When the single yarn fineness is less than 0.5 dtex, yarn breakage frequently occurs in the spinning / drawing process, the operability deteriorates, and the mechanical strength of the obtained long fiber nonwoven fabric is inferior. . On the other hand, when the single yarn fineness exceeds 11 dtex, the spinning yarn is inferior in cooling property, and the yarns tend to adhere to each other.

  The heat-resistant polylactic acid-based long fiber nonwoven fabric of the present invention is a nonwoven fabric in which the composite long fibers described above are deposited, and the fibers are thermally bonded to each other when the copolymer polyester coated with the polylactic acid-based polymer melts or softens. And keep the form. As a form of thermal bonding, by passing through a hot air treatment device or a hot roll device, it may be thermally bonded at the contact point between the fibers via the melted or softened copolyester, By passing through a heat embossing device, a part having a partial thermocompression bonding part, that is, a thermocompression bonding part in which the copolyester is melted or softened by partial application of heat and pressure, and a non-thermocompression bonding part The shape may be retained as a non-woven fabric having

  In addition, the heat-resistant polylactic acid-based long fiber nonwoven fabric of the present invention is such that the constituent long fibers at the partial temporary thermocompression bonding points between the pre-formed fibers formed by melting or softening the copolyester are needle punches or the like thereafter. It has a point-like fused part that is partly peeled off by three-dimensional entanglement processing, and the constituent fibers in the non-fused part other than the point-like fused part are mutually tangled three-dimensionally and integrated as a whole It may be realized.

The heat-resistant polylactic acid-based long fiber nonwoven fabric of the present invention preferably has a basis weight in the range of ²⁰ to 300 g / m ² , more preferably 30 to 200 g / m ² . If the basis weight is less than 20 g / m ² , the formation and mechanical strength are inferior and impractical. On the other hand, when the basis weight exceeds 300 g / m ² , it is disadvantageous in terms of cost.

  The heat-resistant polylactic acid-based long fiber nonwoven fabric of the present invention has a tensile strength at 90 ° C. of 80 to 200 N / 5 cm width, and the elongation at break at 90 ° C. is 30% or more in both the vertical and horizontal directions. Is preferred.

Next, the preferable manufacturing method of the heat resistant polylactic acid type | system | group continuous nonwoven fabric of this invention is demonstrated.
The heat-resistant polylactic acid-based long fiber nonwoven fabric of the present invention can be efficiently produced by, for example, a spunbond method.

  That is, first, a polylactic acid polymer and a copolyester containing the aforementioned components are prepared. Each prepared polymer is melt-metered individually, and melt-spun through a core-sheath type composite spinneret in which a polylactic acid-based polymer forms a core part and a copolymer polyester forms a sheath part. Further, the spun yarn is cooled using a conventionally known cooling device such as a horizontal spray or an annular spray, and then pulled and thinned using a suction device. Alternatively, the polylactic acid-based polymer forms a core portion and the copolymer polyester melt-spins through a multi-leaf type composite spinneret that forms a leaf portion, and is similarly processed.

  The pulling speed at this time is preferably set to 4000 to 6000 m / min, and more preferably 4500 to 5500 m / min. When the pulling speed is less than 4000 m / min, the molecular orientation is not sufficiently promoted in the yarn, and the dimensional stability of the obtained long fiber nonwoven fabric is inferior. On the other hand, if the pulling speed is too high, the spinning stability is poor.

  The drawn and thinned long fibers are deposited on a movable collection surface such as a conveyor made of a screen while opening with a known opening device to form a web. In the same manner, the heat-resistant polylactic acid-based composite continuous fiber of the present invention can be produced.

  Next, the obtained web is subjected to heat treatment to melt or soften the copolymer polyester component outside the fiber, thereby thermally bonding the fibers together to obtain the heat-resistant polylactic acid-based long fiber nonwoven fabric of the present invention.

  Examples of the heat treatment method include a method of blowing hot air, a method of passing through a hot embossing device, and the like, but in terms of obtaining a nonwoven fabric excellent in both mechanical strength and flexibility, it is preferable to pass through a hot embossing device.

The temperature during the heat treatment may be set to a temperature at which the copolymerized polyester component melts or softens, but is appropriately selected according to the treatment time and the like.
For example, in the case where the long-fiber nonwoven fabric retains its shape by melting or softening the copolyester in the partial thermocompression bonding part, the surface temperature of the roll when passing through the hot embossing device is the melting point of the copolyester component It is preferable to set the temperature lower by 10 to 50 ° C. If the temperature is set lower than 50 ° C. above the melting point of the copolyester, the copolyester will not melt or soften sufficiently, resulting in inferior adhesive function. It becomes. On the other hand, when the temperature is set higher than the temperature lower by 10 ° C. than the melting point of the copolyester, the molten polymer adheres to the roll and the operability is significantly impaired.

In addition, as a form of the long-fiber nonwoven fabric, when it is a nonwoven fabric that is entangled and integrated by needle punching after partial temporary thermocompression treatment using a hot embossing device, the surface temperature of the roll when passing through the hot embossing device is The temperature is preferably set to 60 to 100 ° C. lower than the melting point of the copolyester component. If the temperature is set lower than 100 ° C. lower than the melting point of the copolyester, the web will not be able to withstand the tension during the process of transporting the web for producing the long-fiber non-woven fabric, and the fibers will be removed from the web. The problem that cannot be held occurs. On the other hand, when the temperature is set to a temperature lower than 60 ° C. higher than the melting point of the copolyester, the fibers in the thermocompression bonding part are excessively fused, and the fibers are separated by a three-dimensional entanglement process such as a needle punch and free fiber state However, the fibers are cut from the crimped portion, and the constituent fibers tend not to be entangled well.
(Example)
Next, based on an Example, this invention is demonstrated concretely. However, the present invention is not limited only to these examples. In addition, the various physical-property values in a following example and a comparative example were measured with the following method.
(1) Melt flow rate (g / 10 min): Measured at a temperature of 210 ° C. and a load of 2160 gf according to the method described in ASTM-D-1238 (E). Hereinafter, the melt flow rate is referred to as “MFR”.
(2) Relative viscosity (ηrel): 0.5 g of a sample was dissolved in 100 cc of a mixed solvent having an equal mass ratio of phenol and ethane tetrachloride and measured using an Ostwald viscometer.
(3) Melting point Tm (° C.), glass transition temperature Tg (° C.), crystallization temperature Tc (° C.): a differential scanning calorimeter (Perkin Elma, DSC-2 type) was used, and the sample mass was 5 mg. Measurement was performed at a temperature elevation rate of 10 ° C./min.
(4) Fineness (Decitex, hereinafter referred to as “dtex”): The fiber diameter of 50 fibers in the web state was measured with an optical microscope, and the average value obtained by density correction was defined as the fineness.
(5) Weight per unit area (g / m ² ): Ten sample pieces having a length of 10 cm and a width of 5 cm were prepared from a sample in a standard state, and after making the equilibrium moisture, the weight (g) of each sample piece was weighed. An average value of the obtained values was converted per unit area to obtain a basis weight (g / m ² ).
(6) Tensile strength (N / 5 cm width) and elongation at break (%): Measured according to JIS-L-1906. That is, 10 pieces of sample pieces each having a length of 20 cm and a width of 5 cm were prepared for the warp direction and the weft direction of the nonwoven fabric, and a constant-speed extension type tensile tester (Tensilon UTM-4- manufactured by Orientec Co., Ltd.) was prepared for each sample piece. 1-100), and stretched at a gripping interval of 10 cm and a tensile speed of 20 cm / min, and the average value of the obtained load value at the time of cutting (N / 5 cm width) was taken as the tensile strength (N / 5 cm width). The average value of elongation was defined as elongation at break (%).
(7) Tensile strength (N / 5 cm width) and elongation at break (%) in a high temperature atmosphere: Measured according to JIS-L-1906 in a high temperature atmosphere at 90 ° C. That is, 10 pieces of sample pieces each having a length of 20 cm and a width of 5 cm were produced in the warp direction and the weft direction of the nonwoven fabric. After using a constant speed extension type tensile testing machine (Tensilon UTM-4-1-100 manufactured by Orientec Co., Ltd.) in a high temperature atmosphere of 90 ° C., holding a sample piece at a spacing of 10 cm and leaving it for 5 minutes, Elongation was performed at a tensile speed of 20 cm / min, and the average value of the obtained load value at the time of cutting (N / 5 cm width) was defined as the tensile strength (N / 5 cm width) in a high-temperature atmosphere, and the average value of elongation at break was The elongation at break (%) in a high temperature atmosphere.
(Production of copolymer polyester-1)
A mixture of terephthalic acid (TPA) and ethylene glycol (EG) slurry (molar ratio 1 / 1.6) was continuously added to an esterification reaction vessel in which bis (β-hydroxyethyl) terephthalate and its low polymer exist. Then, the reaction was carried out under the conditions of a temperature of 250 ° C. and a pressure of 0.1 MPaG, and the residence time was 8 hours, and an esterified product having a reaction rate of 95% was continuously obtained. This was transferred to a polycondensation reaction vessel, 45 mol% of 1,4-butanediol (1,4-BD) and 55 mol% of ethylene glycol (EG) were added, and tetrabutyl titanate was used as a polycondensation catalyst. Was added at 2 × 10 ⁻⁴ mol / acid component mol, and the esterification reaction was carried out for 1 hour while stirring at a temperature of 200 ° C. and a pressure of 0.1 MPa. Next, the temperature in the reactor was raised to 240 ° C. in 30 minutes, and the pressure in the reactor was gradually reduced to 1.2 hPa or less after 70 minutes. The polycondensation reaction was carried out for 3 hours with stirring under these conditions to obtain a copolyester (P1). The obtained copolyester (P1) had a relative viscosity (ηrel) = 1.39, Tm = 180 ° C., Tg = 48 ° C., and Tc = 120 ° C.
(Production of copolyester-2)
In Production-1 of the above copolyester, the ratios of 1,4-BD and EG were 30 mol% for 1,4-BD and 70 mol% for EG. Other than that, copolymer polyester (P2) was obtained in the same manner as in Production of copolymer polyester-1 above. The obtained copolyester (P2) had a relative viscosity (ηrel) = 1.45, Tm = 200 ° C., Tg = 50 ° C., and Tc = 125 ° C.
Example 1
As a polylactic acid polymer, L-lactic acid / D-lactic acid copolymer (P3) having a melting point of 168 ° C. and an MFR of 20 g / 10 min, L-lactic acid / D-lactic acid = 98.6 / 1.4 mol% is prepared. did.

On the other hand, P1 was prepared as a copolyester. Furthermore, a master batch containing 20% by mass of talc based on P3 was separately prepared.
Individually, P3 is the core, P1 is the sheath, and the core / sheath is 1/1 (mass ratio), and the talc is 0.5% by mass in the molten polymer. Each polymer was melted at a temperature of 230 ° C. using a separate extruder-type melt extruder, and melted under the condition of a single-hole discharge rate of 1.38 g / min so as to have a core-sheath type composite cross section. Spinned.

  After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 4500 m / min with an air soccer provided below the spinneret, and opened using a known fiber opening device, It was collected and deposited as a composite long fiber web on a moving screen conveyor. The single filament fineness of the deposited composite long fibers was 3.0 dtex.

Next, the web was passed through a hot embossing device composed of an embossing roll and a smooth metal roll to perform heat treatment, and a heat-resistant polylactic acid-based long fiber nonwoven fabric having a basis weight of 140 g / m ² was obtained. As heat embossing conditions, the surface temperature of both rolls is 140 ° C., and the embossing roll is a circular sculpture pattern with an individual area of 0.6 mm ² , the density of crimping points is 20 points / cm ² , and the crimping area ratio is 12 % Was used.

  Table 1 shows the physical properties and the like of the obtained nonwoven fabric.

（実施例２）
Ｐ３とＰ１との複合比をＰ３／Ｐ１＝２／１（質量比）とした。そして、それ以外は実施例１と同様にして、耐熱性ポリ乳酸系長繊維不織布を得た。

(Example 2)
The composite ratio of P3 and P1 was P3 / P1 = 2/1 (mass ratio). And otherwise, it carried out similarly to Example 1, and obtained the heat resistant polylactic acid-type long fiber nonwoven fabric.

Table 1 shows the physical properties and the like of the obtained nonwoven fabric.
(Examples 3 and 4)
The basis weight of the nonwoven fabric was 100 g / m ² (Example 3) and 50 g / m ² (Example 4). And otherwise, it carried out similarly to Example 1, and obtained the heat resistant polylactic acid-type long fiber nonwoven fabric.

Table 1 shows the physical properties and the like of the obtained nonwoven fabric.
(Example 5)
Partial temporary press-bonding points were formed at a surface temperature of both rolls of 105 ° C. during heat treatment through a hot embossing apparatus. Further, needle punching (NP) was performed after the heat treatment. That is, a web having a partially pre-bonded point formed thereon is subjected to needle punching using a # 40 regular barb punch needle under the conditions of a needle depth of 14 mm and a punch density of 65 punch / cm ² , and the inter-component fibers are tertiary. Originally entangled, a heat resistant polylactic acid-based long fiber nonwoven fabric was obtained. And otherwise, it carried out similarly to Example 1, and obtained the heat resistant polylactic acid-type long fiber nonwoven fabric.

Table 1 shows the physical properties and the like of the obtained nonwoven fabric.
(Example 6)
The pulling speed was 4000 m / min, and the single yarn fineness of the obtained composite long fiber was 3.4 decitex. And otherwise, it carried out similarly to Example 1, and obtained the heat resistant polylactic acid-type long fiber nonwoven fabric.

Table 1 shows the physical properties and the like of the obtained nonwoven fabric.
(Example 7)
The spinning temperature was 240 ° C. The pulling speed was 5500 m / min, and the single yarn fineness of the obtained composite continuous fiber was 2.3 decitex. And otherwise, it carried out similarly to Example 1, and obtained the heat resistant polylactic acid-type long fiber nonwoven fabric.

Table 1 shows the physical properties and the like of the obtained nonwoven fabric.
(Example 8)
P3 was prepared as a polylactic acid polymer, and P2 was prepared as a copolyester. Further, a master batch containing 20% by mass of talc based on P3 was used.

  Individually, P3 is the core, P1 is the sheath, and the core / sheath is 1/1 (mass ratio), and the talc is 0.5% by mass in the molten polymer. Each polymer was melted at a temperature of 240 ° C. using a separate extruder-type melt extruder, and melted under the condition of a single-hole discharge rate of 1.38 g / min so as to obtain a core-sheath type composite cross section. Spinned.

  After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 4500 m / min with an air soccer provided below the spinneret, and opened using a known opening device, It was collected and deposited as a composite long fiber web on a moving screen conveyor. The single filament fineness of the deposited composite long fibers was 3.0 dtex.

Next, the web was passed through a hot embossing device composed of an embossing roll and a smooth metal roll, and heat-treated to obtain a heat-resistant polylactic acid-based long fiber nonwoven fabric having a basis weight of 100 g / m ² . As heat embossing conditions, the surface temperature of both rolls is set to 155 ° C., and the embossing roll is a circular sculpture pattern with an individual area of 0.6 mm ² , the density of crimping points is 20 points / cm ² , and the crimping area ratio is 12 % Was used.

Table 1 shows the physical properties and the like of the obtained nonwoven fabric.
Example 9
As a polylactic acid-based polymer, an L-lactic acid / D-lactic acid copolymer (P4) having a melting point of 168 ° C. and an MFR of 60 g / 10 min, L-lactic acid / D-lactic acid = 98.6 / 1.4 mol% is prepared. did. On the other hand, P1 was prepared as a copolyester. Further, a master batch containing 20% by mass of talc based on P4 was used.

  Individually, P4 is the core, P1 is the leaf, and core / leaf is 1/1 (mass ratio), and talc is 0.5% by mass in the molten polymer. Each of the polymers is melted at a temperature of 230 ° C. using a separate extruder-type melt extruder, and a six-leaf type having a fiber cross section having a core portion and six leaf portions as shown in FIG. Using a composite die, melt spinning was performed under a single-hole discharge rate of 1.38 g / min.

  After cooling the spun yarn with a known cooling device, it is subsequently pulverized with a pulling speed of 4000 m / min with an air soccer provided below the spinneret, and is opened using a known opening device, It was collected and deposited as a composite long fiber web on a moving screen conveyor. In addition, the single yarn fineness of the deposited composite long fiber was 3.4 dtex.

Next, the web was passed through a hot embossing device composed of an embossing roll and a smooth metal roll, and heat-treated to obtain a heat-resistant polylactic acid-based long fiber nonwoven fabric having a basis weight of 100 g / m ² . As heat embossing conditions, the surface temperature of both rolls is 140 ° C., and the embossing roll is a circular sculpture pattern with an individual area of 0.6 mm ² , the density of crimping points is 20 points / cm ² , and the crimping area ratio is 12 % Was used.

Table 1 shows the physical properties and the like of the obtained nonwoven fabric.
The nonwoven fabrics of Examples 1 to 9 are all excellent in mechanical properties at room temperature and have little decrease in strength even in a high-temperature atmosphere (a strength of about 50% with respect to the strength at room temperature). The heat resistance at high temperature was good.
(Comparative Example 1)
A polylactic acid polymer (P3) was prepared. This polymer P3 was mixed with 0.5% by mass of talc as an additive. A mixture of this polylactic acid polymer and talc was melt-spun in a single phase from a round spinneret at a spinning temperature of 230 ° C. and a single-hole discharge rate of 1.67 g / min. After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 4500 m / min with an air soccer provided below the spinneret, and opened using a known opening device, It was collected and deposited as a web on a moving screen conveyor. The single yarn fineness of the deposited single-phase long fibers was 3.7 dtex.

Next, this web was passed through a hot embossing device consisting of an embossing roll and a smooth metal roll, and heat treated to obtain a polylactic acid-based long fiber nonwoven fabric having a basis weight of 140 g / m ² . As heat embossing conditions, the surface temperature of both rolls is 140 ° C., and the embossing roll is a circular sculpture pattern with an individual area of 0.6 mm ² , the density of crimping points is 20 points / cm ² , and the crimping area ratio is 12 % Was used.

Table 1 shows the physical properties and the like of the obtained nonwoven fabric.
Since the nonwoven fabric of Comparative Example 1 was composed of single-phase long fibers using only a polylactic acid-based polymer, the strength at room temperature was excellent, but the strength decrease under a high-temperature atmosphere was large ( 30% or less of the strength at room temperature).
(Comparative Example 2)
A polyester (P5) copolymerized with 20 mol% of isophthalic acid at the sheath part and having a relative viscosity of 1.38 and a melting point of 190 ° C. was used. Other than that, in the same manner as in Example 1, an attempt was made to produce a polylactic acid-based long fiber nonwoven fabric, which was collected and deposited as a composite long fiber web. The single filament fineness of the deposited composite long fibers was 3.0 dtex.

However, when the heat treatment is performed through a hot embossing apparatus, the web has a large thermal shrinkage, and a nonwoven fabric cannot be obtained.
(Comparative Example 3)
Polyethylene terephthalate (P6) having a relative viscosity of 1.38 and a melting point of 256 ° C. was used for the sheath, and the polylactic acid polymer (P3) used in Example 1 was used for the core.

  Then, after individually weighing so that the core part / sheath part = 1/1 (mass ratio) and talc is 0.5% by mass in the molten polymer, each polymer is individually added. The extruder was melted at a temperature of 285 ° C. using an extruder-type melt extruder, and melt-spun under a single-hole discharge rate of 1.38 g / min so as to have a core-sheath composite cross section.

  I smoked. This indicates that thermal decomposition of the polylactic acid-based polymer has occurred, and the yarn cannot be formed.

It is a schematic diagram which shows an example of the cross section of the multileaf composite type fiber in this invention. It is a schematic diagram which shows the other example of the cross section of the multileaf complex type fiber in this invention.

Explanation of symbols

1 Core 2 Leaf 3 Multileaf type composite fiber

Claims (7)

  A non-woven fabric on which a composite long fiber comprising a polylactic acid polymer and a copolyester containing a terephthalic acid component, an ethylene glycol component and a butanediol component is deposited, and a composite form of the composite long fiber Is a core-sheath composite type in which the polylactic acid-based polymer forms the core and the copolymer polyester forms the sheath, or the polylactic acid-based polymer forms the core, and the copolymer polyester is A heat-resistant polylactic acid-based long-fiber nonwoven fabric, which is a multi-leaf composite type in which a plurality of protruding leaf portions are formed so as to surround the outer periphery of a core portion.   The polymer constituting the composite long fiber has a melting point difference of 50 ° C. or less when the melting point of the polylactic acid polymer is 150 ° C. or higher and the melting point of the copolymer polyester is higher than the melting point of the polylactic acid polymer. The heat-resistant polylactic acid-based long fiber nonwoven fabric according to claim 1, wherein   The heat-resistant polylactic acid-based long fiber nonwoven fabric according to claim 1 or 2, which is integrated by having a partial thermocompression bonding portion.   The composite ratio (mass ratio) of the polylactic acid polymer and the copolyester is polylactic acid polymer / copolyester = 3/1 to 1/1, The heat-resistant polylactic acid-based long fiber nonwoven fabric according to any one of the above.   A polylactic acid-based polymer and a copolymerized polyester containing a terephthalic acid component, an ethylene glycol component, and a butanediol component are constituent components, and the polylactic acid-based polymer forms a core, and the copolymerized polyester is a sheath portion. A core-sheath composite type long fiber, or a polylactic acid-based polymer forms a core part, and a copolyester forms a plurality of protruding leaf parts so as to surround the outer periphery of the core part A heat-resistant polylactic acid-based composite long fiber, which is a multi-leaf composite type long fiber.   6. The melting point of the polylactic acid polymer is 150 ° C. or more, and when the melting point of the copolyester is higher than the melting point of the polylactic acid polymer, the melting point difference is 50 ° C. or less. The heat-resistant polylactic acid-based composite long fiber described.   The composite ratio (mass ratio) of the polylactic acid polymer and the copolyester is polylactic acid polymer / copolyester = 3/1 to 1/1, according to claim 5 or 6. Heat-resistant polylactic acid composite long fiber.

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