JP6158631B2 - tape - Google Patents

Description

  The present invention relates to a tape having biodegradability.

  In plantation cultivation of vegetables, fruit trees, flowers, etc. in alleys and greenhouses, in order to support and attract these plants with support tools such as supports or nets and attracting cords, plant stems, branches, vines, etc. A method of binding to an attracting string, that is, a method of winding a stem, a branch, a vine, etc., a support, and an attracting string with a binding tape and fastening with a stable needle is widely used. Conventionally, a synthetic resin film having no biodegradability such as polyethylene has been used for such a binding tape.

  With tape made of non-biodegradable material, it takes time and effort to cut it off using scissors for separation when it is removed from the support after use, and the amount of work is large. The removed tape debris becomes a large amount of trash, and it takes a lot of labor and cost to collect and incinerate after collection.

  In recent years, biodegradable products that decompose in nature have attracted attention, and a tape made of a long-fiber nonwoven fabric composed of a biodegradable resin has been proposed (Patent Document 1). Further, according to this technique, a composite fiber having a core-sheath structure composed of a low melting point biodegradable resin and a high melting point biodegradable resin is considered preferable. However, polylactic acid, PBS polymer, and PES polymer, which are specifically listed as low melting point melting point biodegradable resins with a L-form ratio of 96% or less, are not excellent in heat resistance. When used near a facility that generates a high temperature such as a boiler used for storage, or when stored in a warehouse at a high temperature for a long period of time, the nonwoven fabric constituting the tape may be deformed.

JP 2002-101766 A

  It is an object of the present invention to provide a tape that has sufficient mechanical strength and heat resistance for use, is excellent in workability, and does not require labor such as recovery after use.

  The present inventor has reached the present invention as a result of intensive studies to solve the above problems.

  That is, the gist of the present invention is as follows.

It comprises a polylactic acid-based long-fiber non-woven fabric, wherein the non-woven fabric is provided with a polylactic acid-based polymer A in the core and a polylactic acid-based polymer B in the sheath, respectively. The polymer-polymer B has a melting point of 160 ° C. or more as a constituent fiber, and the core-sheath composite fiber is partially thermocompression bonded. A tape, wherein the polymer A and the polylactic acid polymer B satisfy at least one physical property selected from the following (I) to (III).
(I) The polylactic acid-based polymer A and the polylactic acid-based polymer B have a D-form content of 1.5 mol% or less or 98.5 mol% or more, and the polylactic acid-based polymer A melt The index is 7 to 15 g / 10 minutes, and the melt index of the polylactic acid polymer B is 20 to 50 g / 10 minutes.
(II) The D form content in the polylactic acid polymer A and the polylactic acid polymer B is 1.5 mol% or less, and the D form content in the polylactic acid polymer B is a polylactic acid type. It is a high value exceeding the D-form content in the polymer A.
(III) The D form content in the polylactic acid polymer A and the polylactic acid polymer B is 98.5 mol% or more, and the D form content in the polylactic acid polymer B is a polylactic acid polymer. It is a value less than the D-form content rate in A.

  Hereinafter, the present invention will be described in detail.

  The polylactic acid-based long-fiber nonwoven fabric (hereinafter sometimes simply referred to as “long-fiber nonwoven fabric”) used as the material of the tape of the present invention has a polylactic acid-based polymer A disposed in the core and a polylactic acid-based material in the sheath. The core-sheath type composite fiber in which the polymer B is disposed is used as a constituent fiber and is partially thermocompression bonded.

  Examples of the polylactic acid polymer A and the polylactic acid polymer B include poly-D-lactic acid, poly-L-lactic acid, a copolymer of D-lactic acid and L-lactic acid, or a mixture thereof.

  The polylactic acid copolymer A and / or the polylactic acid polymer B may be copolymerized with a hydroxycarboxylic acid as long as the effects of the present invention are not impaired. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, and hydroxyoctanoic acid. Of these, hydroxycaproic acid or glycolic acid is preferred from the viewpoint of degradation performance by microorganisms and cost.

  The melting points of the polylactic acid polymer A and the polylactic acid polymer B need to be 160 ° C. or higher. By setting the melting points of the polylactic acid polymer A and the polylactic acid polymer B to 160 ° C. or higher, the crystallinity can be improved. A nonwoven fabric comprising such a polylactic acid-based polymer as a constituent fiber is remarkably excellent in heat resistance and is less likely to shrink during heat treatment, and thus can be stably heat treated. Furthermore, good strength and elongation are maintained even after heat treatment.

  The melting point of poly-L-lactic acid, which is a homopolymer of polylactic acid, and poly-D-lactic acid is approximately 180 ° C. When a copolymer is used instead of a homopolymer as the polylactic acid-based polymer, the melting point of the copolymer is lowered to less than 160 ° C., resulting in high amorphousness, and thus heat resistance. It becomes inferior. Therefore, in the present invention, it is preferable to determine the copolymerization ratio (molar ratio) of L-lactic acid and D-lactic acid so that the melting point of the copolymer is 160 ° C. or higher. In addition, the copolymerization ratio of L-lactic acid and D-lactic acid will be described later.

The polylactic acid polymer A and the polylactic acid polymer B must satisfy at least one physical property selected from the following (I) to (III).
(I) The polylactic acid-based polymer A and the polylactic acid-based polymer B have a D-form content of 1.5 mol% or less or 98.5 mol% or more, and the polylactic acid-based polymer A melt The index (MI) is 7 to 15 g / 10 min, and the melt index of the polylactic acid polymer B is 20 to 50 g / 10 min.
(II) The D form content in the polylactic acid polymer A and the polylactic acid polymer B is 1.5 mol% or less, and the D form content in the polylactic acid polymer B is a polylactic acid heavy polymer. It is higher than the D-form content in coalescence A.
(III) The D form content in the polylactic acid polymer A and the polylactic acid polymer B is 98.5 mol% or more, and the D form content in the polylactic acid polymer B is a polylactic acid polymer. It is a value less than the D-form content rate in A.

  Next, the above (I) will be described below.

  In polylactic acid-based polymer A and polylactic acid-based polymer B, the D-form content (the content of D-lactic acid in polylactic acid) is 1.5 mol% or less or 98.5 mol% or more. is necessary.

  In general, in a polylactic acid polymer, when L-lactic acid and D-lactic acid, which are optical isomers, are copolymerized, it becomes amorphous and the melting point decreases (that is, the melting point is less than 160 ° C.) In addition, the optical purity tends to decrease. In such a case, the crystallinity and heat resistance are poor. That is, the non-woven fabric having a fiber composed of a polylactic acid polymer having a D-form content of more than 1.5 mol% and less than 98.5 mol% is inferior in crystallinity and heat resistance. . As a result, when a non-woven fabric is formed by performing partial thermocompression bonding described later, only a non-woven fabric having inferior strength and elongation can be obtained.

  Further, in the case of (I), as described above, the MI of the polylactic acid polymer A is 7 to 15 g / 10 minutes, and the MI of the polylactic acid polymer B is 20 to 50 g / 10 minutes. It is necessary to be. When the MI of the polylactic acid-based polymer A is 7 to 15 g / 10 minutes and the MI of the polylactic acid-based polymer B is 20 to 50 g / 10 minutes, the portion subjected to partial thermocompression bonding (embossing) The polylactic acid polymer constituting the sheath part is softened by melting, but the polylactic acid polymer constituting the core part remains while maintaining the strength of the fiber itself. And the intensity | strength of fiber itself can be maintained also in the location where the partial thermocompression bonding was performed due to the fiber strength of the remaining core component. Moreover, by arranging a polylactic acid polymer having a viscosity lower than that of the core portion in the sheath portion, partial thermocompression bonding of the sheath portion can be facilitated, and the strength of the nonwoven fabric can be improved. In particular, it is preferable that the polylactic acid-based polymer A has a melt index of 7 to 10 g / 10 min and the polylactic acid-based polymer B has a melt index of 20 to 35 g / 10 min.

  If the MI of the polylactic acid polymers A and B is out of the above range, operational problems also occur. That is, if the MI value of the polylactic acid-based polymer A is less than 5 g / 10 minutes, the viscosity becomes too high. Therefore, in order to enable spinning in the production process, it is necessary to set the spinning temperature very high. If so, the polylactic acid-based polymer is decomposed, and the resulting fibers and nonwoven fabric have reduced strength. Moreover, when MI of polylactic acid-type polymer B exceeds 50 g / 10min, there exists a problem that a thread breakage will occur frequently because of poor spinnability.

  That is, a polylactic acid-based long fiber nonwoven fabric that is excellent in all of heat resistance, strength, and elongation by using a core-sheath type composite fiber satisfying the above physical properties (I) as a constituent fiber and making it into a nonwoven fabric by partial thermocompression bonding. Can be obtained.

  In the present invention, the polylactic acid-based polymer A and the polylactic acid-based polymer B satisfy the physical properties (I) described above and the physical properties (II) or (III) described later. May be.

  The above (II) and (III) will be described below.

  In (II), as in (I) above, from the viewpoint of crystallinity and heat resistance, the D-form content in the polylactic acid polymer A and the polylactic acid polymer B is 1.5 mol% or less. It is necessary to be. In addition, it is necessary that the D-form content in the polylactic acid-based polymer B is higher than the D-form content in the polylactic acid-based polymer A.

  In (III), as in (I) above, from the viewpoint of crystallinity and heat resistance, the D-form content in the polylactic acid polymer A and the polylactic acid polymer B is 98.5 mol% or more. It is necessary to be. In addition, it is necessary that the D-form content in the polylactic acid polymer B is less than the D-form content in the polylactic acid polymer A.

  When the D-form content in the polylactic acid copolymer disposed in the core and the sheath is within the range of (II) and (III) described above, compared with the sheath component, The core component can be made more excellent in crystallinity and heat resistance. Therefore, when partial thermocompression bonding described later is performed, the polylactic acid polymer constituting the sheath part is easily softened by melting, but the strength of the polylactic acid polymer constituting the core part is maintained. And since the intensity | strength of a core part is maintained even after partial thermocompression bonding, the intensity | strength of core sheath composite fiber itself can be maintained.

  In the polylactic acid-based polymer A and the polylactic acid-based polymer B, as long as the effects of the present invention are not impaired, a pigment, a heat stabilizer, an antioxidant, a weathering agent, a flame retardant, and a terminal blocking agent are used as necessary. Additives such as plasticizers, lubricants, mold release agents, antistatic agents and fillers may be added. For example, talc as a crystal nucleating agent may be blended in both the core part and the sheath part.

  Moreover, when containing inert fine particles, such as a talc, it is preferable that the content is 0.1-2.0 mass%. If it is less than 0.1% by mass, a sufficient crystallization promoting effect may not be obtained. On the other hand, if it exceeds 2.0% by mass, the crystallinity may be inferior or thread breakage may occur frequently. The average particle size (D50, a value measured by a laser diffraction method) of such inert fine particles is preferably 0.1 to 5.0 μm. When the thickness is 5.0 μm or more, yarn breakage may easily occur during fiberization. On the other hand, when the particle size is 0.1 μm or less, the particles are likely to aggregate and the dispersibility may be poor.

  In the above-described core-sheath type composite fiber, the composite ratio (mass ratio) of the core part and the sheath part is preferably core part / sheath part = 90 / 10-50 / 50, and 80 / 20-60 / 40. More preferably. When the ratio of the core part exceeds 90% by mass or the ratio of the core part is less than 50% by mass, the mechanical properties may be deteriorated.

  The single-filament fineness of the core-sheath composite fiber is preferably 0.5 to 11 dtex, and more preferably 1.0 to 5.0 dtex. When the single yarn fineness is less than 0.5 dtex, the long fiber nonwoven fabric is inferior in mechanical strength, and is not practical. On the other hand, when the single yarn fineness exceeds 11 dtex, the long fiber nonwoven fabric becomes rigid and tends to be inferior in workability.

  The polylactic acid-based long fiber nonwoven fabric according to the present invention has a partially thermocompression-bonded part (partial thermocompression bonding part) and heat by passing the web on which the core-sheath composite fiber as described above is deposited through a heat embossing device. It becomes a nonwoven fabric which has the part which is not crimped | bonded. In this partial thermocompression bonding portion, the sheath component is in a melted or softened state, and the constituent fibers are bonded to each other.

  In general, the strength of the long-fiber nonwoven fabric depends on the strength of the fibers constituting the nonwoven fabric and the strength of the partial thermocompression bonding portion (embossed portion). Here, although the strength as a non-woven fabric is improved in the partial thermocompression bonding portion, the strength of the constituent fiber itself is lowered because the constituent fiber is melted by heat. However, in the polylactic acid-based long-fiber nonwoven fabric of the present invention, as described in the above (I) to (III), a polymer configuration suitable for partial thermocompression bonding that maintains the core strength and A core-sheath composite fiber is used. Therefore, even if thermocompression bonding is performed, the strength of the fiber itself does not decrease, and a synergistic effect that the strength of the fiber itself and the strength of the nonwoven fabric can be maintained is obtained. In addition, the effect that it can be set as the long-fiber nonwoven fabric also improved in elongation is also produced.

The polylactic acid-based long fiber nonwoven fabric constituting the tape of the present invention preferably has a basis weight of 20 to 100 g / m ² . If the basis weight is less than 20 g / m ² , the mechanical strength may be inferior, which is not practical. On the other hand, when the basis weight exceeds 100 g / m ² , it is disadvantageous in terms of cost, the thickness becomes large, the flexibility is lost, and the handleability tends to be inferior.

The polylactic acid-based long-fiber nonwoven fabric in the present invention preferably satisfies the following physical properties (IV) to (VI).
(IV) The total tensile strength (hereinafter also referred to as “NSM strength”) when converted to a basis weight of 100 g / m ² in the vertical direction and the horizontal direction is 300 N / 5 cm or more.
(V) The breaking elongations in the vertical direction and the horizontal direction are both 20% or more.
(VI) The dry heat shrinkage after treatment at 150 ° C. for 5 minutes is 10% or less.

  Regarding (IV), in the long-fiber nonwoven fabric, the total of the NSM strength in the vertical direction and the horizontal direction is preferably 300 N / 5 cm or more. By setting it to 300 N / 5 cm or more, the tape is preferable because it has sufficient strength to withstand actual use. The vertical direction is the machine direction (MD direction) of the long-fiber nonwoven fabric, and the horizontal direction is the direction (CD direction) perpendicular to the mechanical direction of the long-fiber nonwoven fabric. The vertical direction is the longitudinal direction of the tape, the horizontal direction. The direction is the width direction of the tape.

  Regarding (V), in the long-fiber nonwoven fabric, the breaking elongation in the vertical direction and the horizontal direction is preferably 20% or more, and more preferably 25% or more. When the elongation at break is 20% or more, it has better processability than a non-woven fabric using a normal polylactic acid polymer, and when used as a binding tape for agriculture, it is easy to follow the object to be bound for easy handling. It will be excellent.

  Regarding (VI), in the long fiber nonwoven fabric, the dry heat shrinkage at 150 ° C. is preferably 10% or less, and preferably 5% or less. When the dry heat shrinkage rate at 150 ° C. is 10% or less, it can sufficiently withstand use at high temperatures, and deformation or the like hardly occurs even when stored at high temperatures for a long time.

  An example of a method for producing a polylactic acid-based long-fiber nonwoven fabric constituting the tape of the present invention will be described below. The polylactic acid-based long fiber nonwoven fabric of the present invention can be efficiently produced by a spunbond method.

  First, two types of polylactic acid polymers A and B as described above are prepared and melt-metered individually. Then, melt spinning is performed through the core-sheath composite spinneret so that the polylactic acid-based polymer A forms a core and the polylactic acid-based polymer B forms a sheath. The spun yarn spun from the spinneret is cooled using a conventionally known cooling device such as horizontal spraying or annular spraying, and then pulled and thinned using a suction device.

  The pulling speed at the time of pulling is preferably set to 2000 to 5000 m / min, and more preferably set to 3000 to 5000 m / min. When the pulling speed is less than 2000 m / min, molecular orientation is not sufficiently promoted in the yarn, and the dimensional stability of the resulting nonwoven fabric may be inferior. On the other hand, if the pulling speed exceeds 5000 m / min, the spinning stability may be inferior.

  The core-sheath type composite fiber (long fiber) that has been pulled and thinned is opened using a known opening device, and then spread and deposited on a mobile collecting surface such as a screen conveyor to form a nonwoven web. To do. Thereafter, the nonwoven web is partially subjected to thermocompression bonding using a thermocompression bonding apparatus such as a heat embossing apparatus, whereby a polylactic acid-based long fiber nonwoven fabric can be obtained.

  The obtained polylactic acid-based long fiber nonwoven fabric is cut into an appropriate width and length to obtain the tape of the present invention. The tape width is preferably about 0.5 to 5 cm, and the product winding length is preferably about 5 to 100 m. Moreover, what is necessary is just to cut | disconnect and use for an appropriate length at the time of use by using a tape binding machine etc.

  The tape of the present invention can be favorably used as a binding tape to be tied to a support or an attracting string such as a plant stem, branch or vine in plantation cultivation of vegetables, fruit trees, flowers or the like. Moreover, it can be preferably used as a binding tape for agriculture or horticulture as a binding tape for bundling harvested vegetables, fruits and flowers. Moreover, since it is excellent in mechanical strength and heat resistance while having biodegradability, it can also be preferably used for industrial purposes other than farming.

  Since the tape of the present invention is composed of a polylactic acid-based long-fiber nonwoven fabric, it is ultimately decomposed through microorganisms, but such decomposition is difficult to proceed in normal air and has weather resistance. Therefore, the decrease in strength due to sunlight or the like is small, and it can be favorably used as a tape in the agricultural field by maintaining high strength during use. Moreover, since it is excellent in mechanical strength, elongation, and thermal stability, it can be used satisfactorily.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to these examples.

In addition, the evaluation method of each characteristic value of the nonwoven fabric obtained by the Example and the comparative example is as follows.
(1) Weight per unit area (g / m ² )
A 10 cm × 10 cm sample piece was cut from the obtained nonwoven fabric, and 10 points were produced. Each sample piece was weighed in a standard state (20 ° C., 65% RH), and an average value of this weighed was calculated. This average value was converted to mass per unit area and used as the basis weight (g / m ² ) of the nonwoven fabric.
(2) Fineness (dtex)
Fifty constituent fibers were randomly extracted from the state of the deposited web before partial thermocompression bonding, and the fiber diameters were measured with a microscope. This measured value was subjected to density correction, the fineness of each fiber was calculated, and the average value was further obtained as the fineness.
(3) Tensile strength (N / 5cm)
From the obtained non-woven fabric, a sample piece having a sample length of 20 cm and a sample width of 5 cm was cut, and 10 pieces were produced. About each sample piece, using a constant speed extension type tensile tester (Orientec Co., Ltd., “Tensilon UTM-4-1-100”), when it was extended at a grip interval of 10 cm and a tensile speed of 20 cm / min, The breaking load (N / 5 cm) was measured. And the average value of breaking load was made into tensile strength.
(4) Elongation at break (%)
The specimen length before evaluation in the above (3) and L _0, the sample piece length at break as L, was calculated by the following equation.
(Elongation at break) (%) = {(L−L ₀ ) / L ₀ } × 100
(5) NSM strength (N)
The value of the tensile strength obtained in the above (3) was converted to NSM strength (N) by converting per unit weight of 100 g / cm ² .
(6) Tear strength Measured by the pendulum method according to JIS L 1906. In addition, the measurement direction was the accumulation direction of long fibers, and the measurement was performed in the weak MD direction.
(7) Dry heat shrinkage (%)
Five sample pieces of 15 cm × 15 cm were prepared from the obtained nonwoven fabric. Each sample piece was allowed to stand at a temperature of 150 ° C. for 5 minutes, and the shrinkage was calculated by the following equation. The average value of the calculated values was defined as the dry heat shrinkage rate.
(Dry heat shrinkage) (%) = [(15−Lx) / 15] × 100
In the above formula, Lx represents the length of the sample after being left for 5 minutes.
(8) MI (g / 10 min)
According to ASTM-D1238 (L), the measurement was performed under conditions of a temperature of 190 ° C. and a load of 20.2 N.
(9) Melting point Using a differential thermal scanning calorimeter (Perkin Elma, DSC-2 type), measuring the sample mass at 5 mg and the heating rate at 10 ° C./min, the maximum value of the melting endotherm curve obtained. Was the melting point (° C.).

The types of polylactic acid polymers used in Examples and Comparative Examples are as follows.
(A-1)
Copolymer of L-lactic acid and D-lactic acid Melting point: 168 ° C., (L-lactic acid) / (D-lactic acid) = 98.6 / 1.4 (molar ratio), MI: 10 g / 10 minutes (A- 2)
Copolymer of L-lactic acid and D-lactic acid Melting point: 175 ° C., (L-lactic acid) / (D-lactic acid) = 99.3 / 0.7 (molar ratio), MI: 8 g / 10 minutes (A- 3)
Copolymer of L-lactic acid and D-lactic acid Melting point: 168 ° C., (L-lactic acid) / (D-lactic acid) = 98.6 / 1.4 (molar ratio), MI: 60 g / 10 minutes (A- 4)
Copolymer of L-lactic acid and D-lactic acid Melting point: 168 ° C., (L-lactic acid) / (D-lactic acid) = 98.6 / 1.4 (molar ratio), MI: 8 g / 10 minutes (B- 1)
Copolymer of L-lactic acid and D-lactic acid Melting point: 168 ° C., (L-lactic acid) / (D-lactic acid) = 98.6 / 1.4 (molar ratio), MI: 35 g / 10 minutes (B- 2)
Copolymer of L-lactic acid and D-lactic acid Melting point: 150 ° C., (L-lactic acid) / (D-lactic acid) = 95.8 / 4.2 (molar ratio), MI: 35 g / 10 minutes

Example 1
A polylactic acid polymer (A-1) and a polylactic acid polymer (B-1) were prepared. And (B-1) was made to mix | blend talc (average particle diameter: 1.0 micrometer) in the ratio of 0.5 mass%. After individually weighing (A-1) and (B-1) such that (core part) / (sheath part) is 70/30 (mass ratio), a core / sheath composite type die is provided. So that the core-sheath type composite fiber is melted at a spinning temperature of 220 ° C. using an extruder type extruder and (A-1) is arranged in the core part and (B-1) is arranged in the sheath part. Melt spun.

  The spun yarn was cooled with a known cooling device, and subsequently, it was pulled and thinned at a pulling speed of 3500 m / min with an air soccer provided below the spinneret, and opened using a known opening device. Further, it was collected and deposited as a web on a moving screen conveyor. The single yarn fineness of the deposited composite fiber was 3.4 dtex.

Next, this web was subjected to heat treatment through a hot embossing device comprising an embossing roll and a smooth metal roll to obtain a polylactic acid-based long fiber nonwoven fabric having a basis weight of 20 g / m ² . As the heat embossing condition, the surface temperature of both rolls was set to 125 ° C. As the embossing roll, a circular engraving pattern having an individual area of 0.6 mm ² , a pressure contact density of 20 points / cm ² and a pressure contact area ratio of 15% was used. Moreover, melting | fusing point of the obtained polylactic acid-type long fiber nonwoven fabric was 168 degreeC.

  The obtained long fiber nonwoven fabric was slit to a width of 11 mm, and the tape of the present invention was obtained by making a small volume of 40 m.

Example 2
A tape of the present invention was obtained in the same manner as in Example 1 except that the basis weight was 50 g / m ² .

Example 3
A polylactic acid polymer (A-2) and a polylactic acid polymer (B-1) were prepared. And (A-2) was made to mix | blend talc (average particle diameter: 1.0 micrometer) in the ratio of 0.5 mass%. (A-2) and (B-1) were individually weighed so that (core part) / (sheath part) was 70/30 (mass ratio), and then a core / sheath composite-type die was provided. Melted at an spinning temperature of 220 ° C. using an extruder type extruder and melted so as to be a core-sheath type composite fiber in which (A-2) is arranged in the core part and (B-1) is arranged in the sheath part. Spinned.

  The spun yarn was cooled with a known cooling device, and subsequently, it was pulled and thinned at a pulling speed of 3500 m / min with an air soccer provided below the spinneret, and opened using a known opening device. Further, it was collected and deposited as a web on a moving screen conveyor. The single yarn fineness of the deposited composite fiber was 3.4 dtex.

Next, this web was subjected to heat treatment through a hot embossing device comprising an embossing roll and a smooth metal roll to obtain a polylactic acid-based long fiber nonwoven fabric having a basis weight of 20 g / m ² . As hot embossing conditions, the surface temperature of both rolls was 125 ° C. As the embossing roll, a circular engraving pattern having an individual area of 0.6 mm ² , a pressure contact density of 20 points / cm ² and a pressure contact area ratio of 15% was used. Melting | fusing point of the obtained polylactic acid-type long fiber nonwoven fabric was 174 degreeC and 168 degreeC.

  The obtained long fiber nonwoven fabric was slit to a width of 11 mm, and the tape of the present invention was obtained by making a small volume of 40 m.

Example 4
A tape of the present invention was obtained in the same manner as in Example 3 except that the basis weight was 50 g / m ² .

Example 5
A polylactic acid polymer (A-2) and a polylactic acid polymer (B-1) were prepared. And (A-2) was made to mix | blend talc (average particle diameter: 1.0 micrometer) in the ratio of 0.5 mass%. After individually weighing (A-2) and (B-1) so that (core part) / (sheath part) = 50/50 (mass ratio), a core / sheath composite type die was provided. Melted at an spinning temperature of 220 ° C. using an extruder type extruder and melted so as to be a core-sheath type composite fiber in which (A-2) is arranged in the core part and (B-1) is arranged in the sheath part. Spinned.

  The spun yarn was cooled with a known cooling device, and subsequently, it was pulled and thinned at a pulling speed of 3500 m / min with an air soccer provided below the spinneret, and opened using a known opening device. Further, it was collected and deposited as a web on a moving screen conveyor. In addition, the single yarn fineness of the deposited composite long fiber was 3.4 dtex.

Next, this web was subjected to heat treatment through a hot embossing device comprising an embossing roll and a smooth metal roll to obtain a polylactic acid-based long fiber nonwoven fabric having a basis weight of 20 g / m ² . As hot embossing conditions, the surface temperature of both rolls was 125 ° C. An embossing roll having a circular sculpture pattern with an individual area of 0.6 mm ² , a pressure contact density of 20 points / cm ² , and a pressure contact area ratio of 15% was used. Melting | fusing point of the obtained polylactic acid-type long fiber nonwoven fabric was 174 degreeC and 168 degreeC.

  The obtained long fiber nonwoven fabric was slit to a width of 11 mm, and the tape of the present invention was obtained by making a small volume of 40 m.

Example 6
A tape of the present invention was obtained in the same manner as in Example 5 except that the basis weight was 50 g / m ² .

Comparative Example 1
A polylactic acid polymer (A-3) was prepared, and talc (average particle size: 1.0 μm) was blended therein and melted at a ratio of 0.5 mass%. Then, melt spinning was performed using a spinneret.

  After the discharged yarn is cooled by a cooling device, the screen conveyor is continuously moved by using an air soccer ball provided below the spinneret at a pulling speed of 5000 m / min, opened using a known spreader, and moved. It was collected and deposited as a web on top. The single yarn fineness of the accumulated 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 polylactic acid long fiber nonwoven fabric having a basis weight of 20 g / m ² . As hot embossing conditions, the surface temperature of both rolls was 130 ° C. As the embossing roll, a circular engraving pattern having an individual area of 0.6 mm ² , a pressure contact density of 20 points / cm ² and a pressure contact area ratio of 15% was used. The melting point of the obtained polylactic acid-based long fiber nonwoven fabric was 168 ° C.

  The obtained long fiber nonwoven fabric was slit into a width of 11 mm, and a tape was obtained by making a small roll having a length of 40 m.

Comparative Example 2
A polylactic acid polymer (A-4) and a polylactic acid polymer (B-2) were prepared. And (A-4) was blended with talc (average particle size: 1.0 μm) at a ratio of 0.5 mass%. After individually weighing (A-4) and (B-2) so that (core part) / (sheath part) was 50/50 (mass ratio), a core / sheath composite type die was provided. Melted at a spinning temperature of 220 ° C. using an extruder type extruder and melted so as to be a core-sheath type composite fiber in which (A-4) is arranged in the core part and (B-2) is arranged in the sheath part. Spinned.

  The spun yarn was cooled with a known cooling device, and subsequently, it was pulled and thinned at a pulling speed of 4300 m / min with an air soccer provided below the spinneret, and opened using a known opening device. Further, it was collected and deposited as a web on a moving screen conveyor. In addition, the single yarn fineness of the deposited composite long fiber was 3.0 dtex.

Next, this web was subjected to heat treatment through a hot embossing device comprising an embossing roll and a smooth metal roll to obtain a polylactic acid-based long fiber nonwoven fabric having a basis weight of 20 g / m ² . As hot embossing conditions, the surface temperature of both rolls was 120 ° C. An embossing roll having a circular sculpture pattern with an individual area of 0.6 mm ² , a pressure contact density of 20 points / cm ² , and a pressure contact area ratio of 15% was used. Melting | fusing point of the obtained polylactic acid-type long fiber nonwoven fabric was 168 degreeC and 150 degreeC.

  The obtained long fiber nonwoven fabric was slit into a width of 11 mm, and a tape was obtained by making a small roll having a length of 40 m.

Comparative Example 3
A tape was obtained in the same manner as in Comparative Example 2 except that the basis weight was 50 g / m ² .

  Table 1 summarizes the physical properties of the nonwoven fabrics constituting the tapes obtained in Examples 1 to 6 and Comparative Examples 1 to 3.

  In the nonwoven fabrics of Examples 1 to 6, even when the basis weight is low, the total NSM strength is 300 N / 5 cm or more, the breaking elongation in the vertical direction and the horizontal direction is 20% or more, and the dryness at 150 ° C. The heat shrinkage rate was 10% or less. That is, it had excellent mechanical properties.

  On the other hand, the nonwoven fabric of Comparative Example 1 had various strengths and elongations because the fibers constituting the nonwoven fabric were not single fibers but single layers.

In the nonwoven fabrics of Comparative Examples 2-3, the melting point of the polylactic acid polymer disposed in the sheath portion of the core-sheath composite fiber constituting the nonwoven fabric was as low as 150 ° C., so that the heat resistance was significantly inferior, and the dry heat shrinkage rate Could not be measured. Further, it was inferior in strength and elongation.

Claims (4)

It comprises a polylactic acid-based long-fiber non-woven fabric, wherein the non-woven fabric is provided with a polylactic acid-based polymer A in the core and a polylactic acid-based polymer B in the sheath, respectively. The polymer-polymer B has a melting point of 160 ° C. or more as a constituent fiber, and the core-sheath composite fiber is partially thermocompression bonded. A tape, wherein the polymer A and the polylactic acid polymer B satisfy at least one physical property selected from the following (I) to (III).
(I) The polylactic acid-based polymer A and the polylactic acid-based polymer B have a D-form content of 1.5 mol% or less or 98.5 mol% or more, and the polylactic acid-based polymer A melt The index is 7 to 15 g / 10 minutes, and the melt index of the polylactic acid polymer B is 20 to 50 g / 10 minutes.
(II) The D form content in the polylactic acid polymer A and the polylactic acid polymer B is 1.5 mol% or less, and the D form content in the polylactic acid polymer B is a polylactic acid type. It is a high value exceeding the D-form content in the polymer A.
(III) The D form content in the polylactic acid polymer A and the polylactic acid polymer B is 98.5 mol% or more, and the D form content in the polylactic acid polymer B is a polylactic acid polymer. It is a value less than the D-form content rate in A. The tape according to claim 1, wherein the following physical properties (IV) to (VI) are satisfied at the same time.
(IV) The total tensile strength when converted to a basis weight of 100 g / m ² in the vertical direction and the horizontal direction is 300 N / 5 cm or more.
(V) The breaking elongations in the vertical direction and the horizontal direction are both 20% or more.
(VI) The dry heat shrinkage after treatment at 150 ° C. for 5 minutes is 10% or less.   The tape according to claim 1 or 2, wherein a mass ratio of the core part to the sheath part in the core-sheath type composite fiber is (core part) / (sheath part) = 90/10 to 50/50. . The agricultural binding tape which consists of a tape of any one of Claims 1-3.