JP2007084988A - Polylactic acid-based filament nonwoven fabric and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable nonwoven fabric having good yarn-making property and opening property of constituent fiber, capable of being produced by spunbonding method, excellent in mechanical physical properties and also having heat-sealing property and to provide a method for producing the nonwoven fabric. <P>SOLUTION: The nonwoven fabric is formed by a spunbonding method using a conjugate fiber as a constituent fiber. The conjugate fiber comprises a polylactic acid-based polymer having ≥150°C melting point and an aliphatic polyester copolymer having a melting point lower than that of the polylactic acid-based polymer and forming at least a part of the fiber surface. The aliphatic polyester copolymer comprises an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as components and the copolymer is cross-linked. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polylactic acid-based long fiber nonwoven fabric and a method for producing the same.

  Conventionally, there is a nonwoven fabric made of self-adhesive fibers as one of functional nonwoven fabrics. This non-woven fabric made of self-adhesive fibers is one in which a part of the fibers is melted by heating and the fibers are bonded and integrated, and has heat sealing properties.

  In recent years, synthetic fibers made from petroleum have a large calorific value during incineration, so it has been necessary to review them from the viewpoint of protecting the natural environment, and fibers made of aliphatic polyester that biodegrades in nature have been developed. Contributing to protection is expected. Among aliphatic polyesters, polylactic acid polymers have a relatively high melting point (about 180 ° C.) and are expected to be used in a wide range of fields.

  When trying to obtain a non-woven fabric made of self-adhesive fibers using a polylactic acid-based polymer, polylactic acid is arranged in the core portion, and a copolymer of D-lactic acid and L-lactic acid (D, An L-lactic acid copolymer) is arranged to form a nonwoven fabric with a core-sheath type composite fiber having a sheath part having a lower melting point than the core part (Patent Documents 1 and 2).

In this case, considering the thermal processing stability, it is preferable that the difference in melting point between the core and the sheath is larger. Therefore, a copolymer having a low melting point (a copolymer having a temperature of about 120 ° C.) is selected as the copolymer for the sheath. It is considered good. However, in the D, L-lactic acid copolymer, those having a melting point of about 120 ° C. have low crystallinity, so that troubles such as shrinkage or fusion to a heat roll are likely to occur in the heat bonding process, and The resulting nonwoven fabric is inferior in heat resistance. In addition, when a polymer having a low melting point other than polylactic acid is selected as the sheath component instead of this, the glass transition temperature (Tg) is often low. When trying to obtain, the spunbond method has a very short distance (spinning process-cooling / stretching process) until the yarn discharged from the nozzle hole is pulled and thinned. There existed problems, such as showing rubber-like elasticity and causing the yarns to block each other.
JP 07-310236 A JP-A-07-133511

  In the present invention, the constituent fibers are good in spinning and spreading properties, and can be produced by a spunbond method. The obtained nonwoven fabric has excellent mechanical properties and a biodegradable property that combines heat sealing properties. It is an object to provide a nonwoven fabric and a method for producing the same.

  In order to solve the above problems, the present inventors have studied to obtain a nonwoven fabric by a spunbond method using a polymer having a low melting point and a low Tg. As a result, it was found that when an organic peroxide was melted and mixed with the polymer, the crystallization rate was increased, and sufficient cooling and blocking did not occur even in the cooling process by the spunbond method. The present invention has been made based on such knowledge.

That is, the means for solving the above-described problems are as follows.
1. A nonwoven fabric formed by a spunbond method using a composite fiber as a constituent fiber, the composite fiber comprising a polylactic acid polymer having a melting point of 150 ° C. or higher, and an aliphatic polyester having a melting point lower than that of the polylactic acid polymer And the aliphatic polyester copolymer forms at least part of the fiber surface, and the aliphatic polyester copolymer comprises an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid. A polylactic acid-based long-fiber non-woven fabric characterized by comprising an acid as a constituent component and being crosslinked.

  2. In the aliphatic polyester copolymer, the aliphatic diol is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, the aliphatic hydroxycarboxylic acid is lactic acid, and the melting point thereof is a polylactic acid polymer. 1. It is lower by 50 ° C. than the melting point of 1. Polylactic acid long fiber nonwoven fabric.

  3. The composite long fiber is a core-sheath type composite continuous fiber in which a polylactic acid-based polymer forms a core part and an aliphatic polyester copolymer forms a sheath part, and the composite ratio of the core part and the sheath part ( (Mass ratio) is core / sheath = 3/1 to 1/3. Or 2. Polylactic acid long fiber nonwoven fabric.

  4). A polylactic acid polymer having a melting point of 150 ° C. or higher is used, and an aliphatic polyester copolymer having an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as a constituent component and having a lower melting point than the polylactic acid polymer. Using a polymer in which a polymer and an organic peroxide are previously melt-mixed, each of the polymers used is individually melted, and the aliphatic polyester copolymer is at least part of the fiber surface in the fiber cross section. Spinning with a composite spinneret that forms a fiber, cooling the spun yarn spun from the base, thinning it, pulling it open, and depositing the resulting long fibers to form a nonwoven web A method for producing a polylactic acid-based long fiber nonwoven fabric, characterized in that it is formed.

  5. 3. A polymer containing 0.01 to 1 part by weight of an organic peroxide with respect to 100 parts by weight of an aliphatic polyester copolymer is used as the melt-mixed polymer. Of producing a polylactic acid-based long-fiber nonwoven fabric.

  6). As a melt-mixed polymer, the temperature is raised to 200 ° C. at a temperature rising rate of 500 ° C./min, held in that state for 5 minutes, then lowered to 90 ° C. at a temperature lowering rate of 500 ° C./min, and held at 90 ° C. 3. A polymer having a crystallization rate index of 3 minutes or less when subjected to isothermal crystallization and differential thermal analysis is used. Or 5. Of producing a polylactic acid-based long-fiber nonwoven fabric.

  7). A polylactic acid polymer having a melting point of 150 ° C. or higher, an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid as constituents and an aliphatic polyester copolymer having a lower melting point than the polylactic acid polymer. The polylactic acid polymer is melted using an union and an organic peroxide, and the aliphatic polyester copolymer is mixed with the organic peroxide and the polylactic acid polymer. Separately melted and spun using a composite spinneret in which the aliphatic polyester copolymer forms at least a part of the fiber surface in the cross section of the fiber, and the spun yarn spun from the base is cooled and pulled A method for producing a polylactic acid-based long-fiber nonwoven fabric, characterized in that the non-woven web is formed by thinning and opening the fibers, and depositing the obtained long fibers.

  8). Above 1. To 3. It is formed of a polylactic acid-based long-fiber nonwoven fabric as described above, and is configured in a bag shape by having a heat seal part in which constituent fibers are bonded to each other by melting or softening of an aliphatic polyester copolymer A biodegradable bag-like product characterized by

  9. An aliphatic polyester copolymer forming a constituent fiber of a nonwoven fabric formed by a spunbond method, the aliphatic polyester copolymer comprising an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as constituent components An aliphatic polyester copolymer, wherein 100 parts by mass and 0.01 to 1 part by mass of an organic peroxide are melt-mixed.

10. 8. Decomposition temperature of organic peroxide or organic peroxide composition containing organic peroxide is 90 ° C. or higher and 200 ° C. or lower. Aliphatic polyester copolymer.
11. 8. The aliphatic polyester copolymer is characterized in that the aliphatic diol is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, and the aliphatic hydroxycarboxylic acid is lactic acid. Or 10. Aliphatic polyester copolymer.

  12 The temperature is raised to 200 ° C. at a temperature rising rate of 500 ° C./min, held in that state for 5 minutes, then lowered to 90 ° C. at a temperature lowering rate of 500 ° C./min, held at 90 ° C., and subjected to isothermal crystallization. 8. Crystallization rate index when thermal analysis is 3 minutes or less To 11. Any aliphatic polyester copolymer up to.

  According to the present invention, a polylactic acid-based polymer and an aliphatic polyester copolymer are included, and the aliphatic polyester copolymer is a composite composed of an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid. Since the non-woven fabric is formed of fibers and the melting point of the polylactic acid polymer is 150 ° C. or higher, an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid having a lower melting point are used as components. The difference in melting point with the aliphatic polyester copolymer to be made can be about 40 ° C. to 60 ° C., so that a nonwoven fabric excellent in stability during heat processing and excellent in heat sealability can be obtained.

  Further, according to the production method of the present invention, by using an organic peroxide, an aliphatic polyester copolymer comprising an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as a constituent component is crosslinked. The crystallization speed of the aliphatic polyester copolymer can be increased. Therefore, compared with the production process of short fiber nonwoven fabric, the distance from the spinning process to the cooling / drawing process must be limited. Even in the production process of non-spun bond nonwoven fabric, the aliphatic polyester copolymer can be cooled and crystallized well, which effectively prevents the occurrence of blocking in the fiber opening process, A nonwoven fabric can be obtained.

  The biodegradable bag-like material of the present invention is formed of the above-described polylactic acid-based long fiber nonwoven fabric, and has a heat seal part in which constituent fibers are bonded to each other by melting or softening of an aliphatic polyester copolymer. Since it is configured in a bag shape, the polylactic acid polymer having a higher melting point than the aliphatic polyester copolymer maintains the fiber form without being affected by heat in the heat seal part, so that it is sufficient. A heat-sealing strength can be obtained, and a bag-like product having excellent heat-sealing properties can be obtained. Also, since the polylactic acid polymer has a melting point of 150 ° C. or higher, it has high crystallinity and heat stability, and since the aliphatic polyester copolymer is crosslinked, it is the same as the polylactic acid polymer. Further, it has an advantage that it has high crystallinity and excellent thermal stability, and therefore heat shrinkage hardly occurs during heat sealing.

  In addition, the biodegradable bag-like material of the present invention is a triangular corner of a cooking place, a draining bag installed at a drain outlet, a warmer bag storing and using a heat generating agent, a cooling agent bag storing and using a coolant, It can be used for filter bags for beverages such as tea, tea and coffee, various liquid absorbent materials and various bag-like products such as wrapping bags for packaging various products, and can be suitably used as a general living material. Moreover, in order to show the outstanding heat-sealing power not only for general living materials, it can also be used as a bag-like product for agriculture or industry.

  According to the aliphatic polyester copolymer of the present invention, 100 parts by mass of an aliphatic polyester copolymer comprising an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid as constituent components; By being melt-mixed with 01 to 1 part by mass, a crosslinked structure can be effectively introduced into the aliphatic polyester copolymer, so that it can be sufficiently cooled and blocked even in the cooling process by the spunbond method. It can be prevented from occurring, and the constituent fibers of the nonwoven fabric formed by the spunbond method can be formed satisfactorily.

  The nonwoven fabric of the present invention contains a polylactic acid polymer having a melting point of 150 ° C. or more as a fiber-forming component and an aliphatic polyester copolymer as a thermal adhesive component having a lower melting point than the polylactic acid polymer.

First, the polylactic acid polymer will be described.
As the polylactic acid-based polymer used for the nonwoven fabric of the present invention and the bag-like product using the same, poly-D-lactic acid, poly-L-lactic acid, a copolymer of D-lactic acid and L-lactic acid, It is selected from the group consisting of a copolymer of D-lactic acid and hydroxycarboxylic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, and a copolymer of D-lactic acid, L-lactic acid and hydroxycarboxylic acid. Examples thereof include polymers and blends thereof. Examples of the hydroxycarboxylic acid 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 above polylactic acid polymer having a melting point of 150 ° C. or higher or a blend thereof is used. When the melting point of the polylactic acid polymer is 150 ° C. or higher, the polylactic acid polymer has high crystallinity, so that shrinkage during the heat treatment is less likely to occur, and the heat treatment can be stably performed.

  The melting point of poly-L-lactic acid and poly-D-lactic acid, which are homopolymers of polylactic acid, is about 180 ° C. When a copolymer of L-lactic acid and D-lactic acid is used as the polylactic acid polymer, the copolymerization ratio of the monomer components is determined so that the melting point of the copolymer is 150 ° C. or higher. That is, 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.

  Next, an aliphatic polyester copolymer having a lower melting point than the polylactic acid polymer will be described. This aliphatic polyester copolymer contains an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as constituent components.

  Aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedi Methanol. These may be used alone or a mixture thereof. In consideration of the physical properties of the obtained copolymer, it is preferable to use 1,4-butanediol.

  Examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, suberic acid, dodecanedioic acid, and the like, and acid anhydrides that are derivatives thereof may be used. Considering the physical properties of the resulting copolymer, succinic acid or succinic anhydride, or a mixture of these with adipic acid is preferable.

  Aliphatic hydroxycarboxylic acids include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 2-hydroxyisocaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3- Examples include 3-methyl lactic acid, leucine acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, methyl lactic acid, caprolactone, and valerolactone. Two or more of these aliphatic hydroxycarboxylic acids may be used in combination. Of these, lactic acid is preferably used.

  Further, when an optical isomer exists in the aliphatic hydroxycarboxylic acid, any of D-form, L-form or racemic form may be used, and the aliphatic hydroxycarboxylic acid is a solid, liquid or oligomer. There may be.

  As the aliphatic polyester copolymer, specifically, an aliphatic polyester copolymer in which the aliphatic diol is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, and the aliphatic hydroxycarboxylic acid is lactic acid. A polymer, that is, a copolymer obtained by copolymerizing lactic acid with polybutylene succinate can be preferably used. As such an aliphatic polyester copolymer, it is preferable to use what is described in patent 3402006 specification, for example. As such an aliphatic polyester copolymer, specifically, trade name GSPla (crystal melting point 110 ° C.) manufactured by Mitsubishi Chemical Corporation can be preferably used. When the product name GSPla manufactured by Mitsubishi Chemical Corporation is used, since the aliphatic polyester copolymer is copolymerized with lactic acid, the compatibility with the polylactic acid polymer is improved. Therefore, composite spinning can be performed satisfactorily in the melt spinning process. In order to improve the thermal adhesiveness of the nonwoven fabric and to improve the heat sealability of the resulting nonwoven fabric, the melting point difference between the polylactic acid polymer and the aliphatic polyester copolymer is 50 ° C. or more. Preferably there is.

  The aliphatic polyester copolymer is obtained by melt-mixing an organic peroxide at the raw material stage, whereby crosslinking is performed, and the crystallization speed of the aliphatic polyester copolymer is increased. Compared to the manufacturing process of nonwoven fabrics, the aliphatic polyester copolymer can be cooled well even in the manufacturing process of spunbonded nonwoven fabric, which must be a short distance from the spinning process to the cooling / stretching process. Therefore, the occurrence of blocking in the fiber opening process can be effectively prevented.

  The organic peroxide preferably has a temperature (decomposition temperature) at which decomposition starts when the sample 1 g is heated at a rate of 4 ° C./min with an electric heating plate (rapid heating test) at 90 ° C. or higher and 200 ° C. or lower. More preferably, it is 90 degreeC or more and 200 degrees C or less. When the decomposition temperature is higher than 200 ° C., it is difficult to generate radicals at the time of melt mixing with the aliphatic polyester, and the aliphatic polyester is less likely to cause a crosslinking reaction. When the decomposition temperature is lower than 90 ° C., radicals are likely to be generated before the organic peroxide is sufficiently dispersed in the aliphatic polyester, so that a local reaction occurs and a uniform crosslinking reaction product is obtained. Or sometimes local explosive reactions occur. Since this decomposition temperature also changes depending on the purity of the organic oxide, it is also possible to change the purity of the composition containing the organic peroxide, that is, the organic peroxide composition within the above range. It is.

  Specific examples of organic peroxides include benzoyl peroxide, bis (butylperoxy) trimethylcyclohexane, bis (butylperoxy) cyclododecane, butylbis (butylperoxy) valerate, dicumyl peroxide, butylperoxybenzoate , Dibutyl peroxide, bis (butylperoxy) diisopropylbenzene, dimethyldi (butylperoxy) hexane, dimethyldi (butylperoxy) hexyne, butylperoxycumene and the like.

  The blending amount of the organic peroxide in the melt mixing is preferably 0.01 to 1 part by weight, more preferably 0.01 to 0.5 part by weight with respect to 100 parts by weight of the aliphatic polyester copolymer. More preferred is 0.01 to 0.3 parts by mass. If the amount is less than 0.01 part by mass, the required effect of improving the crystallization rate cannot be exhibited. If the amount exceeds 1 part by mass, the copolymer has a high viscosity and tends to be inferior in spinnability during melt spinning.

  In connection with the above points, the aliphatic polyester copolymer melt-mixed with the organic peroxide is heated to 200 ° C. at a temperature rising rate of 500 ° C./min using a DSC apparatus in the raw material stage, Hold for 5 minutes in the molten state and melt, then cool down to 90 ° C at a cooling rate of 500 ° C / min, hold at 90 ° C to cause isothermal crystallization, and the differential crystallization rate index is 3 minutes or less It is preferable that This crystallization rate index is the time (minutes) required to reach one half of the degree of crystallinity finally reached when the polymer is cooled from the molten state at 200 ° C. and crystallized at 90 ° C. The smaller the index, the faster the crystallization rate. Therefore, as an aliphatic polyester copolymer used as a raw material for the composite fiber, a high crystallization rate index of 3 minutes or less can be used to improve the cooling property when melt-spun. It is possible to make it difficult to cause blocking at the time of fibering.

  The present inventors presume that the crystallization speed of the aliphatic polyester copolymer as a raw material in the present invention is increased for the following reason. That is, when an organic peroxide is melt-mixed with the aliphatic polyester copolymer, a cross-link is formed in the copolymer, and this cross-linked portion functions as a nucleating agent that promotes crystallization, and the crystallization speed is Estimated to be faster.

  In the present invention, the aliphatic polyester copolymer forms at least a part of the surface of the composite fiber. As a fiber cross-sectional form for constituting such a fiber, for example, a side-by-side type composite cross-section in which a polylactic acid polymer and an aliphatic polyester copolymer are bonded together, a polylactic acid polymer forms a core and fat. Core-sheath type composite cross section in which an aliphatic polyester copolymer forms a sheath, a split type composite cross section in which a polylactic acid polymer and an aliphatic polyester copolymer are alternately present on the fiber surface, or a multileaf type composite cross section Etc. Since the aliphatic polyester copolymer plays a role as a thermal adhesive component as will be described later, the core-sheath composite in which the aliphatic polyester copolymer forms the entire surface of the fiber in consideration of this point. A cross section is preferred.

  In the case of a core-sheath composite cross section in which a polylactic acid-based polymer forms a core as a fiber-forming component and an aliphatic polyester copolymer forms a sheath as a heat-bonding component when forming a spunbond nonwoven fabric In the above, the composite ratio (mass ratio) of the core part and the sheath part is preferably core part / sheath part = 3/1 to 1/3. If the ratio of the core part exceeds 3/1, the ratio of the sheath part becomes too small, so the thermal bonding performance tends to be inferior, and the shape retention and mechanical performance of the long-fiber nonwoven fabric tend to be inferior. It becomes difficult to obtain a good heat sealability. On the other hand, when the ratio of the core portion is less than 1/3, the obtained nonwoven fabric has insufficient mechanical strength.

  The nonwoven fabric of the present invention is a spunbonded nonwoven fabric on which the above-described composite fibers are deposited. As the form of the non-woven fabric, those in which the fibers are thermally bonded to each other by melting or softening the aliphatic polyester copolymer component are good, but those in which the constituent fibers are kept in shape by entanglement are also possible. Good. As a form of thermal bonding, it may be one that is thermally bonded via a molten or softened aliphatic polyester copolymer at the contact point between fibers, or partially through a hot embossing device. The heat-bonding part and the non-heat-bonding part may be formed, and the aliphatic polyester copolymer component may be melted or softened in the heat-bonding part and held as a nonwoven fabric.

  It is also a preferable condition in the present invention to select a polymer viscosity suitable for high speed spinning. That is, the viscosity of the polylactic acid-based polymer is abbreviated as “MFR1”, which is a melt flow rate measured at a temperature of 210 ° C. and a load of 20.2 N (2160 gf) in accordance with the method described in ASTM-D-1238. ) Is preferably 10 to 80 g / 10 min, more preferably 20 to 70 g / 10 min. When the MFR1 is less than 10 g / 10 minutes, the viscosity is too high, and the burden on the screw at the time of melting in the manufacturing process increases. On the other hand, when MFR1 exceeds 80 g / 10 min, the viscosity is too low, and yarn breakage tends to occur frequently in the spinning process, and the operability tends to be impaired.

  On the other hand, the viscosity of the aliphatic polyester copolymer is a melt flow rate (hereinafter abbreviated as “MFR2”) measured at a temperature of 190 ° C. and a load of 20.2 N (2160 gf) according to the method described in ASTM-D-1238. Is preferably 20 to 45 g / 10 min. When MFR2 is less than 20 g / 10 min, when an organic peroxide is melt-mixed with an aliphatic polyester copolymer, crosslinking is performed thereby, resulting in a polymer having high viscosity. In the process, it is difficult to withstand the stretching tension, and yarn breakage is likely to occur. On the other hand, when the MFR2 exceeds 45 g / 10 min, the degree of polymerization of the aliphatic polyester copolymer is small, so that even if the organic peroxide is melt-mixed, a sufficient crosslinking reaction is not performed, and thus it was obtained. It is not possible to obtain a crystallization rate sufficient to cool the polymer sufficiently in the spunbond spinning process.

  The viscosity of the polymer obtained by melt-mixing the aliphatic polyester copolymer and the organic peroxide is 210 ° C. under a load of 20.2 N (2160 gf) in accordance with the method described in ASTM-D-1238. Melt flow rate (hereinafter abbreviated as “MFR5”) measured at a melt flow rate (hereinafter abbreviated as “MFR4”) of 10 to 30 g / 10 min, a temperature of 230 ° C. and a load of 20.2 N (2160 gf). Is preferably 20 to 45 g / 10 min. In this way, defining a plurality of values of MFR4 and MFR5 at different temperatures makes it difficult to confirm the degree of cross-linking with only one MFR value under one temperature condition, and it is possible to correctly confirm the degree of cross-linking for the first time with a plurality of MFR values. Because. When the melt flow rate MFR4 at a temperature of 210 ° C. is less than 10 g / 10 min, the degree of cross-linking of the melt-mixed polymer becomes strong. Therefore, the melt spinning process exhibits rubber-like elasticity, and the yarn withstands the stretching tension. It becomes impossible to break and thread breakage is likely to occur. On the other hand, when the melt flow rate MFR5 at a temperature of 230 ° C. exceeds 45 g / 10 minutes, the degree of crosslinking of the melt-mixed polymer is weakened, so the crystallization rate is slow, and therefore the yarns are opened to each other. There is a possibility that it will be in close contact and become a non-woven fabric with poor formation. A more preferable range of the melt flow rate is 20 to 30 g / 10 minutes at both the temperature 210 ° C. and the temperature 230 ° C. By setting it as such a more preferable range, all of a spinning process, an extending | stretching process, and a fiber opening process can be performed without a problem, and a nonwoven fabric with favorable formation can be obtained.

  In the following, the viscosity of a polymer obtained by melt-mixing an aliphatic polyester copolymer and an organic peroxide is a temperature of 190 ° C. and a load of 20.2 N (in accordance with the method described in ASTM-D-1238. The melt flow rate (hereinafter abbreviated as “MFR3”) measured at 2160 gf) may be used.

  The single yarn fineness of the composite fiber constituting the nonwoven fabric of the present invention is preferably 2 to 11 dtex. Polymers prepared by melting and mixing organic peroxides with aliphatic polyester copolymers have high viscosity due to cross-linking, so if the single yarn fineness is less than 2 dtex, the spun yarn cannot withstand the drawing tension in the spinning process. Thread breakage frequently occurs and operability is likely to deteriorate. On the other hand, when the single yarn fineness exceeds 11 dtex, the spinning yarn tends to be inferior in cooling property, and the yarn comes out from the opening device in a state where the yarn is in close contact with heat. It will be very inferior. For these reasons, the single yarn fineness is more preferably 3 to 8 dtex.

The basis weight of the nonwoven fabric of the present invention may be appropriately selected depending on the use of the nonwoven fabric, and is not particularly limited, but is generally in the range of 10 to 300 g / m ² . More preferably, it is the range of 15-200 g / m < ² >. When the basis weight is less than 10 g / m ² , the formation and mechanical strength are inferior, which is not practical. Conversely, if the basis weight exceeds 300 g / m ² , it is disadvantageous in terms of cost.

In particular, when the nonwoven fabric is heat sealed or a bag-like material is formed by heat sealing, the basis weight of the nonwoven fabric is preferably in the range of 15 to 150 g / m ² . If the basis weight is less than 15 g / m ² , the number of fibers constituting the nonwoven fabric is relatively reduced, so that the strength of the heat seal part tends to be inferior. On the other hand, when the basis weight exceeds 150 g / m ² , the thickness of the nonwoven fabric increases, and in the inner layer in the heat seal portion, heat is not sufficiently transmitted during heat seal processing, and it is difficult to obtain excellent heat seal strength.

  The polylactic acid-based polymer and / or the aliphatic polyester copolymer for forming the composite fiber constituting the nonwoven fabric of the present invention are not limited to crystal nucleating agents, pigments, and heat-stable unless the object of the present invention is greatly impaired. Agents, antioxidants, weathering agents, plasticizers, lubricants, mold release agents, antistatic agents, fillers, and the like can be added. For example, it is preferable to blend talc with a polylactic acid polymer as a crystal nucleating agent, and to blend a lubricant with an aliphatic polyester copolymer for further improving the openability.

  The biodegradable bag-like product of the present invention is formed of the above-described nonwoven fabric, and the nonwoven fabric is cut into an appropriate size to form a heat seal portion, thereby forming a bag-like form.

  In the heat seal part, the aliphatic polyester copolymer melts or softens, the fibers adhere to each other, and the polylactic acid polymer is in a state of maintaining the fiber form without being affected by heat. . In order to form such a heat seal part to obtain a bag-like product, a bag making process using a known heat sealer can be applied. The heat sealer treatment conditions (setting temperature, linear pressure, treatment speed) at this time are set to appropriate conditions that melt or soften the aliphatic polyester copolymer and the polylactic acid polymer is not affected by heat. can do.

  The biodegradable bag-like material of the present invention is formed into a bag shape by having such a heat seal portion. The bag-like material may be a so-called bag having a take-out opening on one side, or may be stored with various storage items such as a heat generating agent, a desiccant, and an insect repellent and closed by heat sealing without a mouth. There may be.

  Next, the preferable manufacturing method of the polylactic acid-type long fiber nonwoven fabric of this invention is demonstrated. The polylactic acid long fiber nonwoven fabric of the present invention is produced by a spunbond method. The constituent fibers of the nonwoven fabric can be produced by a compound method or a dry blend method.

  First, the compound method will be described. That is, a polylactic acid-based polymer (chip) having a melting point of 150 ° C. or higher and an aliphatic polyester copolymer having a lower melting point than the aliphatic diol, the aliphatic dicarboxylic acid, and the aliphatic hydroxycarboxylic acid. A component (chip) mixed with an organic peroxide by melt mixing is prepared. In the aliphatic polyester copolymer, when the organic peroxide is mixed by melt mixing, the organic peroxide is 0.01 to 1 mass with respect to 100 mass parts of the aliphatic polyester copolymer as described above. It is preferable that they are partially mixed. The copolymer (chip) thus obtained preferably has a crystallization rate index of 3 minutes or less.

  Then, each prepared polymer chip is melt-metered individually, and the low melting point polymer is melt-spun through a composite spinneret capable of forming at least a part of the surface of the composite fiber. The spun yarn that has been spun is cooled using a conventionally known cooling device such as a horizontal spraying or an annular spraying, and then pulled and thinned using a suction device.

  Next, the dry blend method, which is another preferred method for producing the polylactic acid-based long fiber nonwoven fabric of the present invention, will be described. That is, a polylactic acid-based polymer having a melting point of 150 ° C. or higher, and an aliphatic polyester copolymer having a lower melting point than that, comprising an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid as constituent components And the organic peroxide are prepared. And while melting a polylactic acid-type polymer, apart from this, an aliphatic polyester copolymer and an organic peroxide are measured and mixed, and it melt-mixes in an extruder. Then, in the cross section of the fiber, the aliphatic polyester copolymer is spun using a composite spinneret capable of forming at least a part of the fiber surface, and the spun yarn spun from this spinneret is similarly conventionally used. After cooling using a known cooling device such as horizontal spraying or annular spraying, it is pulled down and pulled using a suction device.

  The traction speed during traction thinning is preferably set to 1000 to 4000 m / min, and more preferably 1000 to 3000 m / min. When the pulling speed is less than 1000 m / min, the molecular orientation is not sufficiently promoted in the yarn, and the dimensional stability of the resulting nonwoven fabric tends to be poor. On the other hand, when the pulling speed exceeds 4000 m / min, the spun yarn cannot withstand the pulling tension due to the cross-linking of the aliphatic polyester copolymer by the organic peroxide, and yarn breakage occurs. It tends to be inferior in stability. In the present invention, an aliphatic polyester copolymer having a low Tg is generally used, and even when a low pulling speed of 2000 m / min or less is employed in the spunbond method as described above, an aliphatic group is used. The copolymer formed crosslinks by melt mixing of the organic peroxide into the polyester copolymer, and the crystallization speed was increased, so that the crystallization, that is, the crystal orientation was sufficiently advanced even with the spunbond method. Fiber can be obtained.

  The drawn and drawn composite long fiber is opened using a known opening device. At this time, as described above, the aliphatic polyester copolymer was cross-linked, and the crystallization speed was high, so that the spinning process to the cooling / stretching process were limited compared to the manufacturing process of the short fiber nonwoven fabric and the like. Even in the production process of a spunbond nonwoven fabric that must be carried out at a short distance, and even when a pulling speed of 2000 m / min or less is adopted in the production process of this spunbond nonwoven fabric, an aliphatic polyester copolymer is used. It can be cooled and solidified satisfactorily, and the occurrence of blocking between yarns in the fiber opening process can be effectively prevented.

  After opening, the nonwoven web is formed by opening and depositing on a mobile collection surface such as a screen conveyor. Then, what is necessary is just to make a nonwoven fabric by the well-known nonwoven-fabrication means, for example, heat-treats this nonwoven web, and heat-bonds fibers by softening or melting the aliphatic polyester copolymer of the fiber surface. As a thermal bonding method, it is preferable to perform partial thermocompression bonding using a thermocompression bonding apparatus such as a heat embossing apparatus.

  The temperature of the roll in the hot embossing device may be set to a temperature at which the low melting point aliphatic polyester copolymer melts or softens, and in detail, is appropriately selected according to the processing time, linear pressure, and the like. Specifically, the surface temperature of the roll is preferably set in a range from a temperature 20 ° C. to a temperature 20 ° C. higher than the melting point of the low melting point aliphatic polyester copolymer. However, the temperature of the roll should be 30 ° C. or more lower than the melting point of the polylactic acid polymer so that the polylactic acid polymer of the fiber forming component does not melt or soften and lose its original function. Preferably, it is more preferably 40 ° C. or lower.

  When the temperature of the roll in the hot embossing apparatus is set to a temperature lower than the melting point of the low melting point aliphatic polyester copolymer by 20 ° C., the aliphatic polyester copolymer as the heat bonding component is sufficiently melted or Since it does not soften, it cannot be sufficiently bonded, and the strength is likely to decrease, and it becomes easy to fluff. On the other hand, if the temperature is set higher than 20 ° C. higher than the melting point of the aliphatic polyester copolymer, the polylactic acid polymer is easily affected by heat, causing heat shrinkage or mechanical strength. It becomes a non-woven fabric that is poor.

  By heat-treating under the above temperature conditions, the polylactic acid-based polymer as the fiber-forming component can be heat-treated at a temperature that is not affected by heat such as heat shrinkage, so that thermal processing stability is good and obtained. The flexibility of the nonwoven fabric can be improved.

  According to the present invention, the aliphatic polyester copolymer comprising an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid as a constituent component is crosslinked by mixing with an organic peroxide. The thermal shrinkage at the time is small, and a flexible nonwoven fabric and bag-like material can be obtained. Note that the organic peroxide melt-mixed with the aliphatic polyester copolymer volatilizes at the stage of melt-mixing, so that it is hardly contained in the final product.

  Next, based on an Example, this invention is demonstrated concretely. However, the present invention is not limited only to these examples. In addition, the measurement of various physical property values in the following examples and comparative examples was carried out by the following methods.

(1) Melting point (° C):
Using a differential scanning calorimeter (manufactured by Perkin Elma, DSC-2 type), the sample mass was measured at 5 mg and the heating rate was 10 ° C./min, and the temperature giving the maximum value of the obtained endothermic curve was the melting point. (° C).

(2) Melt flow rate of polylactic acid polymer [MFR1] (g / 10 min):
According to the method described in ASTM-D-1238 (E), the temperature was 210 ° C. and the load was 20.2 N (2160 gf).

(3) Melt flow rate of aliphatic copolyester [MFR2] (g / 10 min):
In accordance with the method described in ASTM-D-1238 (E), the measurement was performed under conditions of a temperature of 190 ° C. and a load of 20.2 N (2160 gf).

(4) Melt flow rate [MFR3, MFR4, MFR5] (g / 10 min) of an aliphatic copolymerized polyester melt-mixed with an organic peroxide:
According to the method described in ASTM-D-1238 (E), the measurement was performed under the conditions of temperatures 190 ° C., 210 ° C., 230 ° C., and a load of 20.2 N (2160 gf). Hereinafter, the melt flow rate measured at 190 ° C. is referred to as “MFR3”, the melt flow rate measured at 210 ° C. is referred to as “MFR4”, and the melt flow rate measured at 230 ° C. is referred to as “MFR5”.

(5) Crystallization rate index (min)
5 mg of sample was heated to 200 ° C at a heating rate of 500 ° C / min, held in that state for 5 minutes, then cooled to 90 ° C at a cooling rate of 500 ° C / min, and held at 90 ° C for isothermal crystallization. It was measured by differential thermal analysis.

(6) Fineness (decitex):
The diameter of 50 fibers in the web state was measured with an optical microscope, and the average value obtained by correcting the density was defined as the fineness.

(7) Spreadability:
The nonwoven web formed with the spun yarn discharged from the opening device was visually evaluated in the following three stages.

◯: Most of the constituent fibers were split, and no contact yarn or convergent yarn was observed.
Δ: Slightly adhered and convergent yarns were observed.
X: Most of the constituent fibers were in close contact with each other, and the opening property was poor.

(8) 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, the mass (g) of each sample piece was weighed, and the average value of the obtained values was converted per unit area to obtain a basis weight ( g / m ² ).

(9) Tensile strength (N / 5 cm width) and elongation (%):
It measured according to JIS-L-1906. That is, 10 sample pieces having a length of 20 cm and a width of 5 cm were prepared, and a constant-speed extension type tensile tester (Tensilon UTM-4-1-1 manufactured by Orientec Co., Ltd.) was used for each sample piece in the longitudinal direction and the weft direction of the nonwoven fabric. 100), and stretched at a gripping interval of 10 cm and a tensile speed of 20 cm / min, and the average value of the resulting breaking load at break (N / 5 cm width) was taken as the tensile strength (N / 5 cm width). The average degree was defined as elongation (%).

(10) Dimensional stability of the nonwoven fabric [dry heat shrinkage (%)]:
When the sheath component melting point of the core-sheath fiber constituting the non-woven fabric is Tm, each sample of length × width = 20 cm × 20 cm after standing for 5 minutes in an atmosphere of (Tm−10) ° C. The sample length of the side was set to L, and it calculated by the following formula. And the thing whose dry heat shrinkage rate is 5% or less in the vertical direction and the horizontal direction evaluated that the dimensional stability of a nonwoven fabric was favorable.

(11) Heat sealability / T-peeling strength (N / 3 cm width):
Two samples having a width of 10 cm and a length of 5 cm were prepared, and the two samples were stacked and heat-sealed, and the heat-sealability was determined by the following three-stage evaluation based on the workability at that time.

○: Shrinkage of the seal portion does not occur during heat seal processing.
Δ: Shrinkage occurs in the heat-sealed portion, resulting in poor dimensional stability.
X: Almost not sealed.

In addition, the heat sealing machine was subjected to heat sealing processing with a sealing width of 1 cm, a heat sealing pressure of 19.6 N / cm ² , a heat sealing time of 1 second, and a heat sealing temperature as described in Table 1 below. . Next, this processed sheet was cut into a width of 3 cm to prepare 10 samples, and a constant speed extension type tensile tester (Tensilon UTM-4-1-1 manufactured by Orientec Co., Ltd.) was used for each sample. 100), the T-peel strength was measured while the heat seal part was stretched at a gripping interval of 5 cm and a tensile speed of 20 cm / min with the heat seal part gradually peeled off. And the maximum value and the minimum value of the load during T-shaped peeling were read, respectively, and the average value was made into the peeling strength of each sample. Further, the average peel strength for 10 samples was defined as a T-shaped peel strength.

(12) Biodegradability:
When a non-woven fabric is embedded in an aged compost maintained at 58 ° C. and taken out after 3 months, the non-woven fabric does not retain its form, or the tensile strength before embedding is retained even if the form is retained. When it decreased to 50% or less with respect to the initial value, the biodegradability was evaluated as good and indicated by ◯. On the other hand, when the nonwoven fabric maintained its form and the tensile strength exceeded 50% with respect to the initial strength before embedding, the biodegradation performance was evaluated as poor and indicated by x.

Example 1
L-lactic acid / D-lactic acid copolymer having a melting point of 168 ° C. and MFR1 of 20 g / 10 min, L-lactic acid / D-lactic acid = 98.4 / 1.6 mol% (hereinafter abbreviated as “P1”) ) Was prepared as a core component.

  In addition, an aliphatic polyester copolymer having a melting point of 110 ° C. and an MFR 2 of 190 g / 10 min at 190 ° C. and having an aliphatic diol, an aliphatic dicarboxylic acid, and lactic acid as constituents (trade name GSPla manufactured by Mitsubishi Chemical Corporation; , Abbreviated as “P2”) and a polymer (chip) prepared by melt-mixing the following organic peroxide at 190 ° C. was prepared by a compound method. That is, 0.075 parts by mass (organic peroxide) of dimethyldi (butylperoxy) hexyne (trade name: Perhexine 25B-40, purity 40%, manufactured by NOF Corporation) as an organic peroxide in the aliphatic polyester copolymer P2. The oxide was added so as to be contained at a concentration of 0.03 parts by mass) and supplied to a twin-screw kneader (TEM-37BS manufactured by Toshiba Machine Co., Ltd.) whose temperature was set to 190 ° C. Then, the strand was extruded from a 0.4 mm diameter × 3 hole die. Subsequently, the strand was cooled with a cooling bath and then cut with a pelletizer to obtain an aliphatic polyester copolymer (hereinafter abbreviated as “P3”) as a sheath component. The resulting crystallization rate index of the aliphatic polyester copolymer of Example 1 was 1.9 minutes. Moreover, MFR3 in 190 degreeC was 13 g / 10min. The reason why the value of MFR was lower than before the organic peroxide was melt-kneaded seems to be that the viscosity was increased due to crosslinking caused by the organic peroxide. In addition, MFR4 in 210 degreeC of the aliphatic polyester copolymer P3 of a sheath component was 20 g / 10min, and MFR5 in 230 degreeC was 28 g / 10min.

Further, a master batch containing 20% by mass of talc (TA) as a crystal nucleating agent based on P1 was prepared.
And individually, so that the composite ratio of P1 and P3 is P1: P3 = 1: 1 by mass ratio, and 0.5 mass% of talc is contained in the molten polymer of P1. After weighing, each is melted at a temperature of 220 ° C. using an individual extruder-type melt extruder, and using a spinneret having a core-sheath-type composite fiber cross section, P1 constitutes the core as described above, and P3 Was melt spun under the condition of a single-hole discharge rate of 1.00 g / min so as to constitute the sheath.

  After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 1600 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. At the time of opening, most of the constituent fibers were separated, and no contact yarn and convergent yarn were observed, and the opening property was good. The single yarn fineness of the deposited composite long fiber was 6.2 decitex.

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 polylactic acid-based long fiber nonwoven fabric having a basis weight of 20 g / m ² . As heat embossing conditions, the surface temperature of both rolls is 90 ° C., and the embossing roll is a circular sculpture pattern with an individual area of 0.6 mm ² , the pressure contact density is 20 / cm ² , and the pressure contact area ratio is 15 % Was used.

  Table 1 shows the performance of the obtained nonwoven fabric.

(Examples 2 and 3)
The basis weight of the long fiber nonwoven fabric was 50 g / m ² (Example 2) and 100 g / m ² (Example 3). And other than that was carried out similarly to Example 1, and obtained the polylactic acid-type long fiber nonwoven fabric.

  Table 1 shows the performance of the obtained nonwoven fabric.

Example 4
The above P1 was prepared as a core component, and the above P2 was prepared as a sheath component.

  In addition, in order that the composite ratio of P1 and P2 is P1: P2 = 1: 1 by mass ratio, 0.5 mass% of talc is contained in the molten polymer of P1, and the examples The organic peroxide used in No. 1 (Nippon Yushi Co., Ltd., trade name: Perhexine 25B-40, purity 40%) is 0.075 parts by mass (as an organic peroxide) with respect to 100 parts by mass of the molten polymer P2. 0.03 parts by mass) After being individually weighed so as to be contained, each is melted at a temperature of 220 ° C. using an individual extruder type melt extruder to form a core-sheath type composite fiber cross section. Was used for melt spinning under the condition of a single-hole discharge rate of 1.00 g / min so that P1 containing talc constitutes the core and P2 containing organic peroxide constitutes the sheath.

  After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 2000 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 web on a moving screen conveyor. At the time of opening, most of the constituent fibers were separated, and no contact yarn and convergent yarn were observed, and the opening property was good. The single yarn fineness of the deposited composite long fiber was 5.0 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 polylactic acid-based long fiber nonwoven fabric having a basis weight of 20 g / m ² . The hot embossing conditions were the same as in Example 1.

  Table 1 shows the performance of the obtained nonwoven fabric.

(Example 5)
The single hole discharge rate was 2.1 g / min, the pulling speed was 2700 m / min, and the single yarn fineness was 7.7 dtex. And other than that was carried out similarly to Example 4, and obtained the polylactic acid-type long fiber nonwoven fabric.

  Table 1 shows the performance of the obtained nonwoven fabric.

(Example 6)
Based on P1, 20% by mass of titanium dioxide (TI) was incorporated instead of talc. And other than that was carried out similarly to Example 4, and obtained the polylactic acid-type long fiber nonwoven fabric.

  Table 1 shows the performance of the obtained nonwoven fabric.

  In all of the nonwoven fabrics of Examples 1 to 6, the polymer for forming the sheath component of the constituent fiber having the core-sheath structure is composed of an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid. Since the dimethyldi (butylperoxy) hexyne as the organic peroxide is melt-mixed at the time of preparation by the compound method or at the time of spinning, the aliphatic polyester copolymer of 1600-2700 m / min. In spite of being pulled at a low speed, the nonwoven webs were generally good in spreadability. Further, the sheet forming performance, heat sealability and biodegradability were good, and the required mechanical performance was obtained.

(Comparative Example 1)
The organic polyester was not contained in the aliphatic polyester copolymer P2. Other than that, melt spinning and nonwoven fabric formation were attempted in the same manner as in Example 4. However, most of the fibers constituting the nonwoven web were in close contact.

(Example 7)
A kitchen draining bag was prepared using the nonwoven fabric of Example 1. That is, a gusset (gusset) is created on both sides of the nonwoven fabric in a cylindrical shape, a 1.5 cm overlap portion is created between the ends of the nonwoven fabric, and a 0.5 cm wide heat seal portion is formed in the overlap portion. Then, a back-sealing seal of the draining bag was formed, and then, a heat-sealing part having a width of 0.5 cm was formed as a bottom part of the draining bag by a heat sealing device to obtain a draining bag having a height of 25 cm and a width of 11 cm. When this drainer bag is used at the kitchen drain, it can collect garbage properly, and the back-opening and the heat seal part at the bottom are firmly sealed, giving a good feeling of use. Obtained.

(Comparative Example 2)
L-lactic acid / D-lactic acid = 98.6 / 1.4 mol% L-lactic acid / D-lactic acid copolymer having a melting point of 168 ° C. and MFR1 of 70 g / 10 min were weighed, and then an individual extruder. Melting was performed using a mold extruder, and spinning was performed at a spinning temperature of 210 ° C. under a single-hole discharge rate of 1.7 g / min so as to obtain a single-phase fiber cross section. After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 5000 m / min with an air soccer installed under the spinneret, opened with a known fiber opening device, and moved. It was collected and deposited as a long fiber web on a screw conveyor. The single yarn fineness of the long fibers was 3.3 dtex. Next, this web was partially heat-welded through a partial heat-welding apparatus composed of an embossing roll having a roll temperature of 90 ° C. to obtain a polylactic acid-based long fiber nonwoven fabric having a basis weight of 20 g / m ² .

  Using the obtained non-woven fabric, an attempt was made to make a draining bag similar to that in Example 7, and the processing temperature of the heat sealing apparatus was set to 150 ° C. Other than that, the heat sealing treatment was performed in the same manner as in Example 7. However, the nonwoven fabrics were not bonded to each other, and the heat sealing portion could not be formed.

(Example 8)
A polylactic acid polymer P1 similar to that in Example 1 was prepared.
In addition, an aliphatic polyester copolymer having a melting point of 110 ° C. and an MFR 2 of 35 g / 10 min at 190 ° C. and having an aliphatic diol, an aliphatic dicarboxylic acid and lactic acid as constituents (trade name GSPla, manufactured by Mitsubishi Chemical Corporation) As an organic peroxide, 0.2 part by mass (0.08 part by mass as an organic peroxide) dimethyldi (butylperoxy) hexyne (trade name: Perhexin 25B-40, purity 40%, manufactured by NOF Corporation) ) And was supplied to a twin-screw kneader (TEM-37BS manufactured by Toshiba Machine Co., Ltd.) whose temperature was set to 190 ° C. Then, the strand was extruded from a 0.4 mm diameter × 3 hole die. Subsequently, the strand was cooled with a cooling bath and then cut with a pelletizer to collect an aliphatic polyester copolymer (hereinafter abbreviated as “P4”). The extrusion discharge amount at that time was 30 kg / h, and the rotation speed of the screw of the biaxial kneader was 200 rpm.

  Table 1 shows the physical properties of the aliphatic polyester copolymer P4 obtained in Example 8. As shown in Table 1, MFR4 at 210 ° C. was 25 g / 10 min, MFR5 at 230 ° C. was 41 g / 10 min, and the crystallization rate index was 1.6 min.

Further, a master batch containing 20% by mass of talc (TA) as a crystal nucleating agent based on P1 was prepared.
And individually, so that the composite ratio of P1 and P4 is P1: P4 = 1: 1 by mass ratio, and 0.5 mass% of talc is contained in the molten polymer of P1. After weighing, each is melted at a temperature of 210 ° C. using an individual extruder-type melt extruder, and using a spinneret having a core-sheath composite fiber cross section, P1 constitutes the core and P4 constitutes the sheath. As configured, melt spinning was performed at a single hole discharge rate of 1.00 g / min.

  After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 2190 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. At the time of opening, most of the constituent fibers were separated, and no contact yarn and convergent yarn were observed, and the opening property was good. The single yarn fineness of the deposited composite long fiber was 4.5 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 polylactic acid-based long fiber nonwoven fabric having a basis weight of 20 g / m ² . As heat embossing conditions, the surface temperature of both rolls is 90 ° C., and the embossing roll is a circular sculpture pattern with an individual area of 0.6 mm ² , the pressure contact density is 20 / cm ² , and the pressure contact area ratio is 15 % Was used.

  Table 1 shows the performance of the obtained nonwoven fabric.

Example 9
Use an aliphatic polyester copolymer (trade name GSPla, manufactured by Mitsubishi Chemical Corp.) having a melting point of 110 ° C. and an MFR2 of 20 g / 10 min at 190 ° C. and comprising an aliphatic diol, an aliphatic dicarboxylic acid, and lactic acid. It was. The same organic peroxide as in Example 8 was added so as to be contained at a concentration of 0.1 part by mass (0.04 part by mass as the organic peroxide). Other than that, an aliphatic polyester copolymer (hereinafter abbreviated as “P5”) was collected in the same manner as in Example 8.

  Table 1 shows the physical properties of the aliphatic polyester copolymer P5 obtained in Example 9. As shown in Table 1, MFR4 at 210 ° C. was 12 g / 10 minutes, MFR5 at 230 ° C. was 21 g / 10 minutes, and the crystallization rate index was 2.2 minutes.

  Next, compared with Example 8, the aliphatic polyester copolymer P4 is changed to the above aliphatic polyester copolymer P5, the melt extrusion temperature is set to 230 ° C., and the traction speed is set to 1400 m / min. did. Otherwise, the web was deposited in the same manner as in Example 8 to obtain a nonwoven fabric. The single yarn fineness of the deposited composite long fiber was 7.1 dtex.

  Table 1 shows the performance of the obtained nonwoven fabric.

(Example 10)
Use an aliphatic polyester copolymer (trade name GSPla, manufactured by Mitsubishi Chemical Corporation) having a melting point of 110 ° C. and an MFR2 of 43 g / 10 min at 190 ° C. and comprising an aliphatic diol, an aliphatic dicarboxylic acid, and lactic acid. It was. The same organic peroxide as in Example 8 was added so as to be contained at a concentration of 0.2 part by mass (0.08 part by mass as the organic peroxide). Other than that, an aliphatic polyester copolymer (hereinafter abbreviated as “P6”) was collected in the same manner as in Example 8.

  Table 1 shows the physical properties of the aliphatic polyester copolymer P6 obtained in Example 10. As shown in Table 1, MFR4 at 210 ° C. was 28 g / 10 min, MFR5 at 230 ° C. was 43 g / 10 min, and the crystallization rate index was 2.7 min.

  Next, compared with Example 8, the aliphatic polyester copolymer P4 is changed to the above aliphatic polyester copolymer P6, the melt extrusion temperature is set to 210 ° C., and the traction speed is set to 2500 m / min. did. Otherwise, the web was deposited in the same manner as in Example 8 to obtain a nonwoven fabric. The single yarn fineness of the deposited composite long fiber was 4.0 dtex.

  Table 1 shows the performance of the obtained nonwoven fabric.

(Example 11)
Dibutyl peroxide (trade name: Perbutyl D, purity 98% or more manufactured by NOF Corporation) was used as the organic peroxide, and 0.027 parts by mass (organic peroxide) was added to the same aliphatic polyester copolymer as in Example 8. The oxide was added so as to be contained at a concentration of 0.027 parts by mass). Other than that, an aliphatic polyester copolymer (hereinafter abbreviated as “P7”) was collected in the same manner as in Example 8.

  Table 1 shows the physical properties of the aliphatic polyester copolymer P7 obtained in Example 11. As shown in Table 1, MFR4 at 210 ° C. was 20 g / 10 min, MFR5 at 230 ° C. was 29 g / 10 min, and the crystallization rate index was 1.0 min.

  Next, compared with Example 8, the aliphatic polyester copolymer P4 is changed to the above aliphatic polyester copolymer P7, the melt extrusion temperature is set to 220 ° C., and the traction speed is set to 1600 m / min. did. Otherwise, the web was deposited in the same manner as in Example 8 to obtain a nonwoven fabric. The single yarn fineness of the deposited composite long fiber was 6.2 decitex.

  Table 1 shows the performance of the obtained nonwoven fabric.

(Example 12)
Dimethyldi (butylperoxy) hexane (trade name: Perhexa 25B-40, purity 40%, manufactured by NOF Corporation) was used as the organic peroxide, and 0.2% was added to the same aliphatic polyester copolymer as in Example 8. It added so that it might be contained by the density | concentration of a mass part (0.08 mass part as an organic peroxide). Other than that, an aliphatic polyester copolymer (hereinafter abbreviated as “P8”) was collected in the same manner as in Example 8.

  Table 1 shows the physical properties of the aliphatic polyester copolymer P8 obtained in Example 12. As shown in Table 1, the MFR4 at 210 ° C. was 21 g / 10 minutes, the MFR5 at 230 ° C. was 32 g / 10 minutes, and the crystallization rate index was 2.4 minutes.

  Next, compared with Example 8, the aliphatic polyester copolymer P4 is changed to the above aliphatic polyester copolymer P8, the melt extrusion temperature is set to 220 ° C., and the traction speed is set to 1800 m / min. did. Otherwise, the web was deposited in the same manner as in Example 8 to obtain a nonwoven fabric. The single yarn fineness of the deposited composite long fiber was 5.5 dtex.

  Table 1 shows the performance of the obtained nonwoven fabric.

(Example 13)
As in Example 12, dimethyldi (butylperoxy) hexane (Nippon Yushi Co., Ltd., trade name: Perhexa 25B-40, purity 40%) was used as the organic peroxide, but this was used as the aliphatic polyester copolymer. It was added so as to be contained at a concentration of 3 parts by mass (0.12 parts by mass as an organic peroxide). Other than that, an aliphatic polyester copolymer (hereinafter abbreviated as “P9”) was collected in the same manner as in Example 12.

  Table 1 shows the physical properties of the aliphatic polyester copolymer P9 obtained in Example 13. As shown in Table 1, MFR4 at 210 ° C. was 18 g / 10 min, MFR5 at 230 ° C. was 28 g / 10 min, and the crystallization rate index was 2.1 min.

  Next, compared with Example 12, the aliphatic polyester copolymer P8 was changed to said aliphatic polyester copolymer P9, and the traction speed | rate was set to 1600 m / min. Otherwise, the web was deposited in the same manner as in Example 12 to obtain a nonwoven fabric. The single yarn fineness of the deposited composite long fiber was 6.2 decitex.

  Table 1 shows the performance of the obtained nonwoven fabric.

  In the nonwoven fabrics of Examples 8 to 13, the polymer for forming the sheath component of the core-sheath constituent fiber is a predetermined aliphatic polyester copolymer, and an organic peroxide is prepared by a compound method. Since the mixture was melt-mixed at the time, the nonwoven web was generally good in terms of spreadability despite being drawn at a relatively low speed. Further, the sheet forming performance, heat sealability and biodegradability were good, and the required mechanical performance was obtained.

Claims (12)

  A nonwoven fabric formed by a spunbond method using a composite fiber as a constituent fiber, the composite fiber comprising a polylactic acid polymer having a melting point of 150 ° C. or higher, and an aliphatic polyester having a melting point lower than that of the polylactic acid polymer And the aliphatic polyester copolymer forms at least part of the fiber surface, and the aliphatic polyester copolymer comprises an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid. A polylactic acid-based long-fiber non-woven fabric characterized by comprising an acid as a constituent component and being crosslinked.   In the aliphatic polyester copolymer, the aliphatic diol is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, the aliphatic hydroxycarboxylic acid is lactic acid, and the melting point thereof is a polylactic acid polymer. The polylactic acid-based long fiber nonwoven fabric according to claim 1, which is lower by 50 ° C. or more than the melting point.   The composite long fiber is a core-sheath type composite continuous fiber in which a polylactic acid-based polymer forms a core part and an aliphatic polyester copolymer forms a sheath part, and the composite ratio of the core part and the sheath part ( The polylactic acid-based long fiber nonwoven fabric according to claim 1 or 2, wherein the mass ratio) is core portion / sheath portion = 3/1 to 1/3.   A polylactic acid polymer having a melting point of 150 ° C. or higher is used, and an aliphatic polyester copolymer having an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as a constituent component and having a lower melting point than the polylactic acid polymer. Using a polymer in which a polymer and an organic peroxide are previously melt-mixed, each of the polymers used is individually melted, and the aliphatic polyester copolymer is at least part of the fiber surface in the fiber cross section. Spinning with a composite spinneret that forms a fiber, cooling the spun yarn spun from the base, thinning it, pulling it open, and depositing the resulting long fibers to form a nonwoven web A method for producing a polylactic acid-based long fiber nonwoven fabric, characterized in that it is formed.   The polylactic acid system according to claim 4, wherein a polymer obtained by mixing 0.01 to 1 part by mass of an organic peroxide with respect to 100 parts by mass of an aliphatic polyester copolymer is used as the melt-mixed polymer. A method for producing a long-fiber nonwoven fabric.   As a melt-mixed polymer, the temperature is raised to 200 ° C. at a temperature rising rate of 500 ° C./min, held in that state for 5 minutes, then lowered to 90 ° C. at a temperature lowering rate of 500 ° C./min, and held at 90 ° C. 6. The method for producing a polylactic acid-based long fiber nonwoven fabric according to claim 4, wherein a polymer having a crystallization rate index of 3 minutes or less when subjected to isothermal crystallization and differential thermal analysis is used.   A polylactic acid polymer having a melting point of 150 ° C. or higher, an aliphatic diol, an aliphatic dicarboxylic acid, and an aliphatic hydroxycarboxylic acid as constituents and an aliphatic polyester copolymer having a lower melting point than the polylactic acid polymer. The polylactic acid polymer is melted using an union and an organic peroxide, and the aliphatic polyester copolymer is mixed with the organic peroxide and the polylactic acid polymer. Separately melted and spun using a composite spinneret in which the aliphatic polyester copolymer forms at least a part of the fiber surface in the cross section of the fiber, and the spun yarn spun from the base is cooled and pulled A method for producing a polylactic acid-based long-fiber nonwoven fabric, characterized in that the non-woven web is formed by thinning and opening the fibers, and depositing the obtained long fibers.   It is formed with the polylactic acid type | system | group long-fiber nonwoven fabric of any one of Claim 1 to 3, By having the heat seal part to which component fibers have adhere | attached by melting or softening of an aliphatic polyester copolymer. A biodegradable bag-like product characterized by being configured in a bag shape.   An aliphatic polyester copolymer forming a constituent fiber of a nonwoven fabric formed by a spunbond method, the aliphatic polyester copolymer comprising an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as constituent components An aliphatic polyester copolymer, wherein 100 parts by mass and 0.01 to 1 part by mass of an organic peroxide are melt-mixed.   The aliphatic polyester copolymer according to claim 9, wherein the decomposition temperature of the organic peroxide or the organic peroxide composition containing the organic peroxide is 90 ° C or higher and 200 ° C or lower.   The aliphatic polyester copolymer is characterized in that the aliphatic diol is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, and the aliphatic hydroxycarboxylic acid is lactic acid. The aliphatic polyester copolymer described.   The temperature is raised to 200 ° C. at a temperature rising rate of 500 ° C./min, held in that state for 5 minutes, then lowered to 90 ° C. at a temperature lowering rate of 500 ° C./min, held at 90 ° C., and subjected to isothermal crystallization. The aliphatic polyester copolymer according to any one of claims 9 to 11, which has a crystallization rate index of 3 minutes or less when subjected to thermal analysis.