JPH09191772A - Biodegradable root cover for raising seedling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable root cover for raising seedlings, formed of a specific nonwoven fabric, directly transplantable without peeling the root cover, having moderate air and water permeabilities and excellent in mechanical strength and handleability. SOLUTION: This biodegradable root cover for raising seedlings is obtained by forming a nonwoven fabric prepared by integrating fibers, comprising a thermoplastic aliphatic polyester having biodegradability such as poly(L-lactic acid) and having 1-15 denier size and 20-80% crystallinity according to three- dimensional interlacing, fusing interstices among the constituent fibers in at least one surface side thereof and converting the at least one surface side into the shape of a porous film by the heat treatment. The biodegradable root cover for raising the seedlings is formed of the nonwoven fabric having 50-300g/m<2> METSUKE (mass per unit area) and has >=5kg/5cm width tensile strength, 30-500cc/m<2> /sec air permeability and 0.02-0.8cm/sec water permeation coefficient expressed in terms of 100kg/m<2> METSUKE.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a seedling raising root cover used in the fields of agriculture and horticulture. More specifically, the present invention relates to a biodegradable root cover for transplanting that does not require removal of the seedling-growing container during transplantation, unlike the conventional seed-covering root cover.

[0002]

2. Description of the Related Art In recent years, with an increasing tendency to return to nature,
Cultivation of green trees for planting in parks, gardens, residential areas, etc. is active. Generally, vegetated trees are grown in plantations to a certain size and then dug up and shipped. However, in such a case, there are two serious problems. That is, the first problem is that, in order to dig up the vegetation tree and ship it, it is necessary to perform a root-wrapping work for protecting the root hair portion, and the work is complicated and the labor cost is high. Also,
The second problem is that when excavated, the roots that are quite thick are also cut off, and they often die without rooting when transplanted. For this reason, transplantation was limited to the early spring when metabolic growth of plants was active.

As a means to solve these problems, first, after digging a hole for planting, a cylindrical container made of woven or knitted fabric or non-woven fabric is placed in the hole, and a sapling is planted in the container to grow for a certain period of time. Later, methods have been developed to dig along the perimeter of the container. By this method, since this container functions as a root cover at the time of shipping, the work of root winding at the time of shipping is not required, which leads to a great simplification of workability, and a thick root can be cut when digging up. Since it does not exist, it is expected that the survival rate will improve and shipping will be possible throughout the year.

As a material for such a root cover, it is necessary to maintain stable mechanical strength for at least 1 to 2 years during the seedling raising period even in the presence of microorganisms in the soil or in a humid environment. Therefore, at present, synthetic fibers partially or wholly made of polyester, nylon, polypropylene or the like are used as a material for the root cover. However, since these synthetic fibers such as polyester are not decomposed in the soil, the root cover in which the roots are entangled must be peeled off when excavating and transplanting / implanting, and its disposal is also a problem. On the other hand, for example, when natural or regenerated fibers such as palm and rayon are used as a material for the root cover, they are decomposed too early by microorganisms in the soil, and thus, they can serve as the original root cover. However, the mechanical strength and dimensional stability in a wet environment are lacking, which causes a problem.

[0005]

The present invention has excellent mechanical strength and has a controlled decomposition performance such that it is hardly decomposed during the seedling raising period and is almost completely decomposed after transplanting. The present invention provides a root cover for biodegradable seedlings, which allows the transplant to be carried out as it is while maintaining the mechanical strength required for replanting and without the need to remove the root cover.

[0006]

In order to solve the above problems, the present invention provides a root cover for raising seedlings for covering a root part of a plant and soil around the root, which is biodegradable. Having a fineness of 1 to 1 made of a thermoplastic aliphatic polyester having
The gist is that a fiber having a denier of 5 to 20 and a crystallinity of 20 to 80% is formed by a non-woven fabric integrated by three-dimensional entanglement.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The fiber applied to the present invention comprises a biodegradable thermoplastic aliphatic polyester as a main component.

Examples of biodegradable thermoplastic aliphatic polyesters include poly (α-hydroxy acids) such as polyglycolic acid and polylactic acid, and copolymers containing these as the main repeating unit elements. Also,
Poly (ω-hydroxyalkanoate) such as poly (ε-caprolactone), poly (β-propiolactone)
In addition, poly-3-hydroxypropionate, poly-3-hydroxybutyrate, poly-3-hydroxycaprolate, poly-3-hydroxyheptanoate,
Poly (β, such as poly-3-hydroxyoctanoate
-Hydroxyalkanoate) and copolymers of the repeating unit elements constituting these and the repeating unit elements constituting poly-3-hydroxyvalerate or poly-4-hydroxybutyrate. As the polyalkylene dicarboxylate consisting of a condensation polymer of glycol and dicarboxylic acid, for example, polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, Examples thereof include polybutylene sebacate, polyhexamethylene sebacate, polyneopentyl oxalate, and polyalkylene dicarboxylate copolymers having repeating unit elements constituting these.

Further, it is also possible to select a plurality of polymers each having such a biodegradability individually and blend them to be applied.

In the present invention, from the viewpoints of biodegradability and spinnability, among others, a polylactic acid-based polymer,
Polymers of polybutylene succinate, polyethylene succinate, polybutylene adipate, polybutylene sebacate or copolymers of these polymers as main repeating units, and polymers of polycaprolactone or polypropiolactone Alternatively, a copolymer containing these polymers as main repeating units, or a blend thereof is suitable.

When the thermoplastic aliphatic polyester is a polylactic acid type polymer, specifically, poly (D-lactic acid),
Among poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, or a copolymer of L-lactic acid and hydroxycarboxylic acid A polymer having a melting point of 80 ° C. or higher is preferable. Here, as the hydroxycarboxylic acid in the case of a copolymer of lactic acid and hydroxycarboxylic acid, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, etc. Can be mentioned.

When the thermoplastic aliphatic polyester is a polyalkylene dicarboxylate, any polymer selected from polybutylene succinate, polyethylene succinate, polybutylene adipate, polybutylene sebacate, or these polymers is used. A copolymer having a main repeating unit is preferable, and specifically, a copolymer composed of 70 mol% or more of butylene succinate and ethylene succinate, butylene adipate, or butylene sebacate is preferable.

The thermoplastic aliphatic polyester is poly (ω
In the case of (hydroxyalkanoate), a polymer of either polycaprolactone or polypropiolactone, or a copolymer containing these polymers as main repeating units is preferable.

Further, in the present invention, the above thermoplastic aliphatic polyester, polycapramide (nylon 6), polytetramethylene adipamide (nylon 4) are used.
6), polyhexamethylene adipamide (nylon 6
6), the constituent fibers of the non-woven fabric can also be formed by an aliphatic polyesteramide-based copolymer which is a condensation polymer with an aliphatic polyamide such as polyundecanamide (nylon 11) and polylauramide (nylon 12). .

The thermoplastic aliphatic polyester according to the present invention has a number average molecular weight of about 20,000 or more, preferably 40,000 or more, more preferably 60,000 or more. In terms of Further, it may be chain-extended with a small amount of diisocyanate or tetracarboxylic dianhydride in order to increase the degree of polymerization.

If necessary, various additives such as a matting agent, a pigment and a crystal nucleating agent may be added to the thermoplastic aliphatic polyester applied in the present invention within a range that does not impair the effects of the present invention. May be added in.

In particular, addition of a crystal nucleating agent such as talc, boron nitride, calcium carbonate, magnesium carbonate and titanium oxide promotes crystallization and improves heat resistance and mechanical strength of the obtained nursery cover. , Spinning
It is preferable in that fusion between yarns (blocking) in the cooling step can be prevented. However, since it is important in the present invention that the crystallinity of the constituent fibers is within a predetermined range, the addition amount is 0.1 to 3.0% by weight, preferably 0.5 to
It is important to use in the range of 2.0% by weight.

Further, addition of a black pigment or dye such as carbon black or black dye is suitable as a root cover for raising seedlings. That is, when it is buried in the ground, the pigment or dye facilitates the absorption of geothermal heat, improves the heat retention of the roots of plants, and contributes to the growth of roots. However, if the amount of addition is too large, the spinnability is lowered when the fiber is spun, so it is preferable to add it in an amount that does not impair spinnability. Addition amount is 0.1
It is important to use in the range of ~ 3.0 wt%, preferably 0.5-2.0 wt%.

The fiber morphology of the constituent fibers of the present invention may be one in which an aliphatic polyester is used alone, or a composite fiber in which two or more kinds of aliphatic polyesters are used. Also,
The cross section of the fiber is, in addition to an ordinary round cross section, a hollow cross section, a modified cross section, a parallel composite cross section, a multi-layer composite cross section, a core-sheath composite cross section, a split composite cross section, and any other fiber depending on the purpose and application. A cross-sectional form may be employed. From the viewpoint of decomposition performance, a hollow cross section, a modified cross section, a split type composite cross section and the like are particularly preferable.

In the present invention, the decomposition rate can be controlled by appropriately selecting the kind of the above-mentioned aliphatic polyester, the copolymerization ratio of the aliphatic polyester, the blending ratio of the aliphatic polyester, the fiber cross section and the like. Thus, a root cover for raising seedlings having a decomposition rate according to the purpose of use can be obtained.

The biodegradable root cover for raising seedlings of the present invention may be in the form of a short fiber or long fiber woven or knitted fabric or a non-woven fabric, but in view of the best cost performance, a long fiber non-woven fabric based base is preferred. .

A method for producing the root cover for raising seedlings of the present invention will be described by taking a long fiber nonwoven fabric as a typical example.
First, the long-fiber non-woven fabric for forming the root cover of the present invention can be efficiently manufactured by the so-called spunbond method. That is, the above-mentioned thermoplastic aliphatic polyester is heated and melted and discharged from the spinneret, and the obtained spun yarn is cooled using a conventionally known cooling device such as horizontal spraying or annular spraying, and then air sucker. Then, the yarn group discharged from the suction device is opened, and then the fibers are spread on a moving deposition device such as a conveyor composed of a screen to form a web. Then, the web formed on the moving and depositing device is subjected to entanglement treatment with a needle punch or a pressurized liquid flow to three-dimensionally entangle the constituent fibers to obtain a long-fiber nonwoven fabric.

Further, if necessary, at least one constituent fiber of the obtained nonwoven fabric is fused by heat treatment, or the obtained nonwoven fabric is impregnated with a binder resin having biodegradability. Therefore, it is preferable that the non-woven fabric has a porous film shape. The non-woven fabric in the form of a porous film allows the plant's capillary roots to penetrate without inhibiting growth, but allows the roots to be retained inside the root cover without penetrating. In the present invention, when the constituent fibers of the non-woven fabric are fused by heat treatment, for example, a hot air thermal through method or a heat calendar method is preferably adopted,
At this time, it is important to appropriately set the treatment conditions so that all the constituent fibers are not melted to eliminate the pores between the fibers. In the present invention, when the nonwoven fabric is impregnated with a binder resin having biodegradability, for example, polyvinyl alcohol, starch, or a binder resin solution or dispersion having biodegradability such as glue is used, The non-woven fabric is immersed and impregnated therein, and then dried.

Then, using the obtained long fiber non-woven fabric as a method for producing a root cover for raising seedlings for covering a root part of a plant and soil around the root, the non-woven fabric is cut into
A method of joining the ends by sewing or heat bonding to form a bag is used. When forming by sewing, it is preferable to use a decomposable suture.
In the case of molding by heat bonding, it can be carried out by a known method such as a heat calendar method or an ultrasonic fusion method.

As a root cover for raising seedlings, when it is buried in soil, a certain level of water permeability and aeration is provided inside and outside the cover so as not to cause a large difference in soil moisture, fertilizer nutrients, oxygen, etc. It is required to have sex. Moreover, the thin roots of the seedlings need to be able to penetrate from the inside to the outside of the cover in order to absorb the nutrients in the soil over a wide range, while the thick roots avoid cutting at the time of excavation during transplantation. It is necessary to stay inside the cover. Therefore, the root cover for raising seedlings is required to have appropriate compactness. Further, it is also important to balance with the decomposition rate of the material, and if the decomposition rate is too fast, the mechanical strength of the material is remarkably reduced, and a thick root is pierced during the seedling raising period, which is not preferable. By keeping the thick roots inside the cover during the seedling raising period, it is possible to improve the survival rate without cutting the thick roots when excavating and transplanting. In the present invention, these requirements are satisfied by setting the fineness and crystallinity of the constituent fibers of the nonwoven fabric within the following predetermined ranges.

It is important that the single filament fineness of the constituent long fibers of the nonwoven fabric constituting the root cover of the present invention is 1 to 15 denier. When the single yarn fineness is less than 1 denier, not only the operability is impaired in the yarn making process, but also the decomposition rate becomes too fast, which is not the object of the present invention. When the single yarn fineness exceeds 15 denier, not only is the cooling property of the spun yarn reduced in the spinning process, but also the flexibility of the resulting nonwoven fabric is impaired, which impairs workability during processing and molding. For these reasons, the single yarn fineness is preferably 2 to 10
Denier is preferable, and 3 to 7 denier is more preferable.

The degree of crystallinity of the constituent fibers of the non-woven fabric forming the root cover for raising seedlings of the present invention should be 20 to 80%, preferably 30 to 70%. here,
The crystallinity is determined by the Roland method from the wide-angle X-ray diffraction pattern of powdered long fibers (nonwoven fabric). When the crystallinity of the fiber is less than 20%, the decomposition in the soil occurs so fast that the object of the present invention cannot be achieved. On the contrary, if it exceeds 80%, not only the flexibility as a fiber is lacked, the spinnability and processability are deteriorated, but also the decomposition rate in the soil is significantly slowed, which is not preferable.

The nonwoven fabric forming the root cover of the present invention preferably has a basis weight of 50 to 300 g / m ² . If the basis weight is less than 50 g / m ² , the resulting root cover for raising seedlings has poor mechanical strength and is poor in practicality. On the other hand, when the basis weight exceeds 300 g / m ² , not only is the cost disadvantageous, but the biodegradation rate tends to decrease. There is a particularly close relationship between the basis weight and the above-mentioned single yarn fineness.For example, if the single yarn fineness is thin, a dense nonwoven fabric will be obtained even if the same basis weight is taken into consideration, but it is considered that the mechanical strength decreases rapidly due to biodegradation. When the mechanical strength of the fiber itself is low, it is necessary to increase the single yarn fineness and the basis weight in order to maintain a certain strength as a nonwoven fabric. Moreover, these non-woven fabrics having a basis weight may be obtained in one step, or may be ones obtained by laminating two or more non-woven fabrics and subjecting them to a pressurized liquid flow treatment or a needle punch treatment.

The root cover for raising seedlings of the present invention has a basis weight of 100
The tensile strength in terms of g / m ² is preferably 5 kg / 5 cm width or more. Tensile strength is 5kg / 5cm
If the width is less than the width, the root cover for raising seedlings may be destroyed because the strength is too weak when soil is added together with the seedlings, which is not preferable. For these reasons, the tensile strength is more preferably 10 kg / 5 cm width or more. This tensile strength can be controlled by the type of polymer used, the fineness and strength of the constituent fibers, the basis weight of the nonwoven fabric, the three-dimensional entanglement treatment conditions of the nonwoven fabric, and the like.

When the nonwoven fabric of the present invention is buried in soil, it is decomposed by microorganisms in the soil and finally decomposed completely. Considering the period for raising plants,
It is hoped that almost no decomposition will occur in the first year, some decomposition will occur in the second year, decomposition will occur to about half in the third year, and decomposition will occur in the fifth year. Based on the tensile strength after burial as compared to the tensile strength before burial, 95% or more in the first year and 80% or more in the second year.
It is considered that the standard is 50% or less in the first year and 5% or less in the fifth year.

The root cover for raising seedlings of the present invention preferably has an air permeability of 30 to 500 cc / cm ² / sec.
If the air permeability is less than 30 cc / cm ² / sec, the air permeability and water permeability are too low, and the action of microorganisms that decompose organic matter in the soil and serve as a nutrient source for plants is slowed down, which leads to the growth of seedlings. Not only is it troublesome, but the capillary root cannot penetrate the root cover, which is not preferable. For these reasons, the air permeability is more preferably 50 cc / cm ² / sec or more. On the contrary, the air permeability is 500 cc / cm
^{If the} area exceeds ² / sec, the voids in the root cover become large and the thick trunk roots penetrate to the outside of the root cover, which is not preferable. This air permeability can be controlled by the type of polymer used, the fineness of the constituent fibers, the basis weight of the nonwoven fabric, and the conditions when heat treatment is performed.

The root cover for raising seedlings of the present invention is JIS-A-
Permeability coefficient measured according to 1218 is 0.02-0.8
It is preferably cm / sec. Permeability coefficient is 0.02c
If it is less than m / sec, the water around the roots of the plant is not drained due to its low water permeability, which may impair the growth of capillary roots or rot the roots of the plants, possibly causing the plants to die. . On the contrary, if the water permeability coefficient exceeds 0.8 cm / sec,
Since the water permeability is too good, there is a risk that not only the roots of the plants but also the thick roots of the plants may penetrate the root cover to the outside. That is, if the water permeability is too good, it means that there is a large opening in the root cover, and the tip of the trunk root projects through this large opening and penetrates into the soil outside.

As described above, in order to satisfy the condition that the degree of crystallinity of the long fiber applied in the present invention is 20 to 80%, the cooling and crystallization of the yarn immediately after spinning are markedly strengthened, and this spinning is performed. It is advisable to draw and draw the yarn thread at a high speed of 1000 to 6000 m / min. Furthermore, it is preferable to add the above-mentioned crystal nucleating agent as needed to improve the cooling property. If the pulling speed is less than 1000 m / min when the spun yarn is towed and thinned, the oriented crystallization of the polymer does not proceed, and the crystallinity of the long fibers becomes less than 20%, so that the mechanical strength of the resulting nonwoven fabric is reduced. On the contrary, when the pulling speed exceeds 6000 m / min, the yarn-forming property deteriorates sharply and the yarn breaks, which is not preferable. In the present invention, in order to increase the crystallinity of the fibers constituting the non-woven fabric, it is effective to heat-treat it in the crystallization region after forming the non-woven fabric. The long-fiber non-woven fabric that constitutes the root cover of the present invention has three-dimensionally entangled webs to maintain the form of the non-woven fabric. That is, since the non-woven fabric shape is integrally held by being entangled three-dimensionally, the non-woven fabric of the present invention can be imparted with excellent flexibility and capillary root passage property, and at the same time entangled three-dimensionally. Therefore, the shape retention of the nonwoven fabric during processing is improved. Here, the three-dimensional entanglement is formed by a pressurized liquid flow process in which a pressurized liquid flow is applied to the web or a needle punch process.

When a three-dimensional entanglement is formed by the pressurized liquid flow treatment, for example, the web obtained by the spunbond method is placed on a moving porous support plate, and the pressurized liquid flow is applied thereto. Then, the constituent long fibers are densely entangled with each other three-dimensionally and integrated as a whole. At this time, if necessary, it is preferable to partially preliminarily heat-bond the web in advance from the viewpoint of the shape stability of the web during the three-dimensional entanglement treatment. The partial provisional thermocompression bonding performed here can be conducted by partial thermocompression bonding treatment using an ordinary embossing roll or ultrasonic fusion treatment. At this time, at least one of the provisional thermocompression bonding portions of the web is It is preferable to appropriately select treatment conditions such as temperature depending on the polymer or the like so that the part can be peeled off by the three-dimensional entanglement treatment and the three-dimensional entanglement can be formed more efficiently.

In order to generate a pressurized liquid fluid, for example, the pore size is 0.05 to 2.0 mm, preferably 0.1 to 2.0 mm.
0.4mm injection hole, 0.3-10mm hole spacing
As a device having a large number of orifices arranged in one row or a plurality of rows, the injection pressure is 5 to 150 kg / cm ² G
A method of ejecting a pressurized liquid is adopted as. When the pressure of the liquid flow is less than 5 kg / cm ² G, it is difficult to separate a part of the thermocompression bonded portion, and three-dimensional entanglement cannot be sufficiently formed between the constituent long fibers. Is 150 kg /
If it exceeds cm ² G, the entanglement between the fibers becomes too dense and the resulting nonwoven fabric tends to be less flexible, which is not preferable. The injection holes are arranged in a row along the direction orthogonal to the traveling direction of the web. When the injection holes are arranged in a plurality of rows, it is preferable that the injection holes are arranged in a staggered manner in order to impart a uniform action of the pressurized liquid flow to the web. A plurality of orifices having injection holes may also be arranged. Water or hot water is generally used as the pressurized liquid. The distance between the injection hole and the web is
It should be 1 to 15 cm. If this distance is less than 1 cm, the texture of the non-woven fabric obtained by this treatment is disturbed, and conversely, if it exceeds 15 cm, the impact force when the liquid flow collides with the web decreases and three-dimensional entanglement is sufficient. Neither is preferable because it is not applied to. Further, when the pressurized liquid flow treatment is performed, the support material for supporting the web may be, for example, a mesh screen such as a wire mesh of 10 to 300 mesh or a perforated plate, which allows the pressurized liquid flow to penetrate the web. There is no particular limitation.

According to the intended use, the web which has been entangled on one side by the above-mentioned method is further inverted, and a pressurized liquid flow is similarly supplied to perform entanglement, so that the front and back are closely integrated. It is possible to obtain a non-woven fabric which is excellent in dimensional stability and mechanical strength.

After performing the pressurized liquid flow treatment, it is necessary to remove excess moisture from the treated web, and a known method can be used for removing excess moisture here. For example, a squeezing device such as a mangle roll is used to mechanically remove excess water to some extent, and subsequently, a remaining amount of water is removed using a drying device such as a continuous hot air dryer. In addition to the normal dry heat treatment, the dry treatment may be a wet heat treatment, if necessary. When performing the drying process, when selecting the processing conditions such as the drying temperature and time, the conditions may be selected not only to simply remove the water but also to allow an appropriate shrinkage.

When the three-dimensional entanglement is performed by the needle punching process, the punch needle is penetrated into the web obtained by the spunbonding method in the same manner as described above, which is partially pre-heat-pressed. At least a part of the thermocompression bonding part is three-dimensionally entangled with the constituent long fibers containing the separated fibers to integrate them as a whole.

Needle punching is performed with a needle depth of 5 to 50 m.
m, is good under the conditions of a punch density of 50 to 400 punches / cm ^2. If the needle depth is less than 5 mm, the degree of entanglement is small and the stability of the form is poor. Also,
When the punch density is less than 50 punches / cm ² , when the temporary thermocompression bonding is performed, the constituent long fibers of the temporary thermocompression bonding portion cannot be well separated due to the mechanical force during the entanglement treatment, and
The fibers are not sufficiently entangled, and the dimensional stability of the non-woven fabric tends to be poor. On the contrary, when it exceeds 400 punches / cm ² , the mechanical strength of the non-woven fabric obtained by cutting the fibers with a punch needle decreases. However, both are not preferable. The punch needle is determined by selecting its thickness, length, number of barbs, type of barbs, etc. according to the single yarn fineness, intended use, and the like.

In carrying out the three-dimensional entanglement treatment in the present invention, either a pressurized liquid flow or needle punching can be employed. When the pressurized liquid flow treatment is performed, a non-woven fabric having a relatively low basis weight (15 to 200 g / m ² ) and particularly excellent flexibility and mechanical strength can be obtained. Also,
Relatively high basis weight (100
˜1000 g / m ² ), a nonwoven fabric excellent in flexibility, air permeability and water permeability can be obtained. This is because the pressurized liquid flow and the needle punch have different web penetrating forces. For example, in the case where a high weight product is subjected to the pressurized liquid flow treatment, the pressurized liquid flow penetrates in the thickness direction of the web. Therefore, only the surface layer of the web is entangled, and a uniform three-dimensional entanglement is not formed on the entire web. Therefore, which processing method to use is
It is desirable to select it appropriately according to the basis weight of the non-woven fabric.

[0041]

The present invention will be described below in detail with reference to examples. Note that the present invention is not limited to only these examples.

In the examples, each physical property value was determined as follows. -Melting point (° C); Differential scanning calorimeter D manufactured by Perkin Elma
The melting point (° C.) was defined as the temperature at which the exothermic value of the melting endothermic curve obtained by using SC-2 type and measuring the temperature rising rate at 20 ° C./min.

Melt flow rate value (g / 10 minutes);
It was measured according to the method described in ASTM-D-1238 (E).

Intrinsic viscosity of polyethylene terephthalate: Measured at a temperature of 20 ° C. using a mixed solution of phenol and ethane tetrachloride in equal weight as a solvent.

Fineness (denier): The fiber diameter in the state of the web was measured with a 50 microscope and the average value of the fineness obtained by density correction was defined as the fineness (denier).

-Unit weight (g / m ² ); 10 pieces each of 10 cm in length × 10 cm in width were prepared from the sample in the standard state, and after reaching equilibrium moisture, the weight (g) of each sample piece was weighed. Then, the average value of the obtained values was converted per unit area to obtain a basis weight (g / m ² ).

Tensile strength (kg / 5 cm width); JIS-
It was measured according to the strip method described in L-1096. That is, 10 pieces each of a sample piece having a sample length of 30 cm and a sample width of 5 cm were prepared, and a constant speed extension type tensile tester (Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co., Ltd.) was prepared.
The maximum tensile strength (kg / 5 cm width) was obtained by stretching each sample piece at a tensile speed of 10 cm / min, and the average value of the obtained maximum tensile strengths was converted into a basis weight of 100 g / m ^2. Was taken as the tensile strength (kg / 5 cm width).

Tear strength (kg); JIS-L-109
According to the Pendulum method described in 6, the measurement was performed using an Elmendorf type tear tester.

Crystallinity (%) of long fibers: measured by wide-angle X-ray method (powdering, Roland method). That is,
In the wide-angle X-ray diffraction method, the interference intensity of the diffracted X-ray is measured in the reflection angle 2θ direction to obtain an interference intensity curve. Then, from the obtained interference intensity curve, an interference peak due to a crystal and a dispersion due to an amorphous part are obtained. The halo and the halo were separated and both were quantified to determine the crystallinity (%) from the following equation.

Crystallinity (%) = (integrated intensity of crystal part / total integrated intensity) × 100

Air permeability (cc / cm ² / sec); JIS-
It was measured according to the Frazier method described in L-1096.
That is, a sample with a sample length of 15 cm and a sample width of 15 cm is 3
Using a Frazier type tester, attach the sample to one end of the cylinder, and then adjust the suction pump so that the tilt barometer shows a pressure of 12.7 mm of water column with a variable resistor. The amount of air passing through the sample piece (c
c / cm ² / sec), and the average value was used as the air permeability.

-Water permeability (cm / sec); JIS-A-1
Based on the constant water level permeability test prescribed in 218, the water temperature is 20 ° C,
The cross-sectional area of the water-permeable cylinder was measured at 3.14 cm ² , and the water permeability coefficient (cm / sec) was calculated. In addition, the larger the permeability coefficient,
Shows good water permeability.

Decomposition performance: A cover used as a sample was buried in the soil by digging a hole, and the decomposition state was visually observed one year, two years, and three years later, and the following four grades were evaluated. ⊚: Almost decomposed ○: Remarkably decomposed Δ: Decomposition is less than half ×: Almost no decomposition Based on the above evaluations, those that decompose as little as possible for 1 to 2 years are considered good. The following comprehensive evaluations were made based on the judgment that it is better to proceed with decomposition after the first year.

◎: Excellent ○: Good △: Poor ×: Non-degradable

Growth condition of seedlings: A container used as a sample is dug in the soil by burying a hole, and a young couscous tree that has been grown on a farm in advance is planted in this container, and after 2 years, outside the container. I dug up along it, carried it to another land as it was, and planted it. Further, one year later, the soil was dug up again to observe the state of root development, and the evaluation was made according to the following three grades.

○: good growth △: normal growth ×: poor growth

Examples 1-3 Poly having a melting point of 115 ° C. and a number average molecular weight of 63,000
Carbon black based on butylene succinate
A master batch containing 30% by weight of
20 weights of talc with a particle size of 1 μm based on the polymer
% Masterbatch containing
And talc in the molten polymer are 1% by weight and 0.4, respectively.
Weighed and compounded so that it will be wt%, single hole discharge amount 1.6g
Ordinary round spinneret with a spinning hole diameter of 0.4 mm under the condition of 1 / min
It was melt spun from gold. The spun yarn was cooled by a cooling device.
After that, an aspirator installed below the spinneret
At a drawing speed of 3600 m / min, the drawing is performed and the fiber is opened.
Opened with a vessel and collected as a web on a moving wire mesh
Deposited. Then, the web is rolled at a roll temperature of 60.
Pass through a partial thermocompression bonding machine consisting of embossed rolls at ℃
Partially thermo-compression bonded and the fineness of single yarn is 4.0 denier
Made of fibers, each weight is 100 g / m ^Two (Example
1), 200g / m^Two (Example 2), 300 g / m^Two 
A long-fiber non-woven web which is (Example 3) was obtained. This non-woven
Uses # 40 regular barb punch needles for the web.
, Needle depth 11 mm, punch density 200 punch / cm^Two of
Needle punching is performed under certain conditions to create a three-dimensional space between the constituent fibers.
Entanglement treatment was performed to obtain a long-fiber nonwoven fabric.

Using the obtained non-woven fabric, a diameter of 30 cm,
A cylindrical bag-shaped root cover for raising seedlings having a height of 30 cm was produced by sewing the joint portion. Then, put this bag-shaped cover in the hole dug in the soil, and then plant a young couscous tree that was grown on the farm in advance in this cover, and after 2 years, dug along the outside of the cover, I brought it to another land and planted it. One year later, the soil was dug up again, and the state of decomposition of the cover and the state of root development were observed. Table 1 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Example 4 The long fiber non-woven fabric having a basis weight of 200 g / m ² obtained in Example 2 was used, and the long fiber non-woven fabric was passed through a continuous hot air dryer for heat treatment. The heat treatment condition is hot air treatment temperature 1
The amount of hot air was adjusted with a damper so that only the constituent fibers on one surface of the nonwoven fabric were fused at 16 ° C., hot air treatment time 60 seconds, and hot air treatment speed 25 m / min. Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed. Table 1 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Examples 5 to 7 The long fiber nonwoven fabric having a basis weight of 200 g / m ² obtained in Example 2 was used, and this long fiber nonwoven fabric was passed through a Yankee dryer for heat treatment. The heat treatment conditions include a drying temperature of 11
The drying time was set to 4 ° C. for 100 seconds, the linear pressure between the felt and the rotating drum was changed, and the volume of hot air was adjusted with a damper so that only the constituent fibers on one surface of the nonwoven fabric were fused. Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed. Table 1 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Example 8 A long fiber non-woven fabric was obtained in the same manner as in Example 4 except that no pigment was added, and after sewing in the same manner as in Example 2, the decomposition state of the cover and the root growth state were observed. did.
Table 2 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.
Shown in

Example 9 The long fiber non-woven web obtained in Example 1 was used, and the non-woven web was subjected to three-dimensional entanglement between constituent fibers by a pressurized liquid flow instead of a needle punch to obtain a long fiber non-woven fabric. Got That is, the obtained nonwoven web was placed on a 30-mesh wire net moving at a speed of 30 m / min and subjected to a pressurized liquid flow treatment with water. This pressurized liquid flow treatment requires a pore size of 0.12
mm of injection holes are arranged in a three-group arrangement with a 1.0 mm hole spacing, and the columnar water flow is adjusted from the position 80 mm above the nonwoven web at a pressure of 60 kg / cm ² G. Let it work. Then, the same treatment was performed once from the front and back of the nonwoven web. Then, after removing excess water from the obtained treated product using a mangle roll, a drying process is performed at a temperature of 60 ° C. using a hot air dryer to obtain a long fiber nonwoven fabric having a basis weight of 100 g / m ^2. It was

Then, after sewing in the same manner as in Example 1, the state of decomposition of the cover and the state of root development were observed.
Table 2 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.
Shown in

Example 10 and Example 11 Except that the single-hole discharge amount was changed to obtain filaments having a single yarn fineness of 2.0 denier (Example 10) and 8.0 denier (Example 11). A long fiber non-woven fabric was obtained in the same manner as in Example 4, and then sewn in the same manner as in Example 4, and then the disassembled state of the cover and the root growth state were observed. Table 2 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Example 12 A masterbatch containing 20% by weight of carbon black based on polycaprolactone having a melting point of 62 ° C. and a melt flow rate value of 30 g / 10 min, and a polymer having a particle diameter of 1 μm as a base. Using a masterbatch containing 15% by weight of talc, 1.0% by weight of each of the pigment and talc in the molten polymer,
The compounding amount is 0.75% by weight, and the spinning temperature is 1
Melt spinning was performed from a rectangular spinneret having a spin hole diameter of 0.5 mm and 400 holes at 90 ° C. and a single hole discharge rate of 3.4 g / min, and a drawing speed was 3000 m / min using a rectangular drawing device, and a roll temperature was set. A long fiber nonwoven fabric having a single yarn fineness of 10 denier was obtained in the same manner as in Example 2 except that the temperature was 20 ° C.
The crystallinity of this long fiber was 65%. Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed. Table 2 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Example 13 AS except that the melting point was changed to 178 ° C. and the temperature was changed to 210 ° C.
A masterbatch containing 20% by weight of carbon black based on poly-L-lactic acid having a melt flow rate value of 20 g / 10 min measured by the method described in TM-D-1238 (E), and the polymer. And a masterbatch containing 10% by weight of talc having a particle diameter of 1 μm as a base, and a pigment and talc are weighed and compounded in the molten polymer to 1.0% by weight and 0.5% by weight, respectively. Then, under the condition of a spinning temperature of 205 ° C., melt spinning is performed from a rectangular spinneret having a spinning hole diameter of 0.4 mm and 680 holes, and is pulled by using a rectangular pulling device, and the roll temperature is set to 1
A long fiber non-woven fabric having a single yarn fineness of 4 denier was obtained in the same manner as in Example 2 except that the temperature was 10 ° C. The crystallinity of this long fiber was 57%. Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed. Table 2 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Example 14 The same as Example 2 except that the long fiber non-woven fabric having a basis weight of 200 g / m ² obtained in Example 2 was used and then the root cover for raising seedlings was heat-bonded by ultrasonic fusion at the joint. After doing
The decomposition state of the cover and the state of root development were observed. The conditions for the ultrasonic fusion treatment were a frequency of 19.5 kHz. Table 2 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Comparative Example 1 Spinning hole diameter of 0.6 mm under the condition of single hole discharge rate of 5.4 g / min.
Melt spinning from a normal round spinneret with a pulling speed of 30
A long fiber non-woven fabric having a single yarn fineness of 16 denier was obtained in the same manner as in Example 2 except that the fiber length was set to 00 m / min. Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed. Table 3 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Comparative Example 2 A spinning hole diameter of 0.3 m under the condition of a single hole discharge rate of 0.32 g / min.
A long fiber non-woven fabric having a single yarn fineness of 0.8 denier was obtained in the same manner as in Example 2 except that melt spinning was performed using a normal round spinneret at m. Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed.
Table 3 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.
Shown in

Comparative Example 3 Butylene succinate / ethylene succinate (70% melting point 92 ° C., melt flow rate value 28 g / 10 min)
Mol% / 30 mol%) a masterbatch containing 20% by weight of carbon black based on the copolymer, and a masterbatch containing 15% by weight of talc with a particle diameter of 1 μm based on the polymer. The pigment and talc were used in the molten polymer at 1.0 respectively.
Weighed and compounded so as to be 0.7% by weight and 680 with a spinning hole diameter of 0.4 mm and a spinning temperature of 145 ° C.
Melt-spinning was performed from a rectangular spinneret having holes, and the filament was drawn using a rectangular towing device, and the roll temperature was set to 50 ° C., in the same manner as in Example 2 to obtain a long-fiber nonwoven fabric with a single yarn fineness of 4 denier. . The crystallinity of this long fiber was 18%.
Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed. Table 3 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Comparative Example 4 Using polyethylene terephthalate having a melting point of 260 ° C. and an intrinsic viscosity of 0.7, melt spinning was performed from a spinneret under the conditions of spinning temperature of 290 ° C. and single hole discharge rate of 2.3 g / min. After the spun yarn is cooled by the cooling device, the aspirator provided below the spinneret subsequently pulls at a speed of 5200 m.
A long-fiber non-woven fabric was obtained in the same manner as in Example 2 except that the fiber was pulled by 10 / min. Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed. Table 3 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.

Comparative Example 5 Using rayon made of 50 mm with 2.0 denier,
After being introduced into the fiber opening machine, melt spinning was carried out from a spinneret under a weighting condition with a parallel card machine and a cross wrapper. After cooling the spun yarn with a cooling device, subsequently, a basis weight of 200 g / m 2 with an aspirator provided below the spinneret.
^Two non-woven webs were made. With this non-woven web,
Needle punching was performed in the same manner as in Example 2 to obtain a long-fiber nonwoven fabric. Then, after sewing in the same manner as in Example 2, the state of decomposition of the cover and the state of root development were observed.
Table 3 shows the observation results at this time and the characteristics of the obtained nonwoven fabric.
Shown in

[0073]

[Table 1]

[0074]

[Table 2]

As is clear from Table 1, the seedling-growing root cover obtained in Example 1 is a cover made of polybutylene succinate, which is a cover made of a non-woven fabric having a fineness and a low basis weight. Characteristics, breathability, water permeability,
Both the biodegradation performance and the growth condition of the seedlings were satisfactory.

The root cover for raising seedlings obtained in Example 2 was made of polybutylene succinate as the material and was a cover using a non-woven fabric having fineness and weighting, so that mechanical properties, air permeability and water permeability were obtained. The biodegradability and seedling growth were satisfactory.

The root cover for raising seedlings obtained in Example 3 was made of polybutylene succinate as a material, and was a cover using a non-woven fabric having a fineness and a high basis weight. After that, it was decomposed by about half and was good overall. Furthermore, regarding the growth condition of the seedlings, the growth was normal probably because the air permeability was a little low and the rooting was a little poor.

The root cover for raising seedlings obtained in Example 4 is superior in mechanical strength to Example 2 because the constituent fibers on one side surface are fused, and it has appropriate water permeability and appropriate air permeability. Because of this, the seedlings were very well grown and biodegradable to the same extent.

The root cover for raising seedlings obtained in Examples 5 to 7 is one in which constituent fibers are fused by a Yankee dryer, and the heat bonding state between the constituent fibers on the surface increases as the linear pressure increases. It was good, but the performance was satisfactory.

The seedling-growing root cover obtained in Example 8 contained no black pigment in the constituent fibers, so that the growth condition of the seedlings was slightly lowered, but other performances were satisfactory.

The root cover for raising seedlings obtained in Example 9 was subjected to a three-dimensional entanglement treatment by a pressurized liquid flow treatment, but the mechanical properties, breathability, water permeability, biodegradability,
The growth condition of the seedlings was satisfactory.

The root cover for raising seedlings obtained in Example 10 is one in which the single yarn fineness of the constituent fibers is thin, but the mechanical properties, air permeability, water permeability, biodegradability, and growth condition of seedlings are satisfactory. It was possible.

The root cover for raising seedlings obtained in Example 11 has a thick monofilament fineness of the constituent fibers, but is satisfactory in mechanical properties, air permeability, water permeability, biodegradability, and growth condition of seedlings. It was possible.

The root cover for raising seedlings obtained in Example 12 was made of polycaprolactone as the material, and the single yarn fineness of the constituent fibers was thickened, but the mechanical properties, breathability, water permeability, biodegradability, seedlings of seedlings were used. The growth was satisfactory.

The root cover for raising seedlings obtained in Example 13 was made of a lactic acid-based material, and was satisfactory in mechanical properties, air permeability, water permeability, biodegradability, and growth condition of seedlings. It was

In the root cover for raising seedlings obtained in Example 14, the sewing form was changed to ultrasonic fusion, but the mechanical characteristics,
The breathability, water permeability, biodegradability, and growth condition of the seedlings were satisfactory.

[0087]

[Table 3]

The root cover for raising seedlings obtained in Comparative Example 1 had 16 denier monofilament fibers as constituent fibers, and although it had excellent mechanical strength, it did not exhibit the target performance of degradability, and also had air permeability. However, because of its high water permeability, the state of growth of the seedlings was also poor.

The root cover for raising seedlings obtained in Comparative Example 2 is suitable as a cover for raising seedlings because the single fiber fineness of the constituent fibers is 0.8 denier and the mechanical strength is excellent, but the decomposition rate is too fast. In addition, since the air permeability and water permeability were low, the growth condition of the seedlings deteriorated.

The root cover for raising seedlings obtained in Comparative Example 3 had a crystallinity of 18% and the decomposition rate was too fast, so it was not suitable as a cover for raising seedlings.

The root cover for raising seedlings obtained in Comparative Example 4 was excellent in mechanical strength because polyethylene terephthalate was used as a raw material, but it was not the object of the present invention because it had no degradability.

The root cover for raising seedlings obtained in Comparative Example 5 was not suitable as a cover for raising seedlings because rayon was used as a material, mechanical strength was rather low, and decomposition rate was too fast.

[0093]

As described above, according to the present invention, the decomposition rate can be controlled by appropriately adjusting the type of the polymer used, the copolymerization amount ratio, the fiber cross-sectional shape and the like.
Almost no decomposition during seedling raising and almost completely after transplantation, which allows transplanting as it is without needing to remove the root cover while maintaining the mechanical strength necessary for transplanting. A root cover for sex raising seedlings can be provided. Furthermore, the root cover for raising seedlings of the present invention,
Since the shape is maintained by the three-dimensional entanglement, it is possible to have appropriate breathability and water permeability and to maintain excellent mechanical strength.

Claims (10)

[Claims] 1. A root cover for raising seedlings for covering a root part of a plant and soil around the root, wherein the fineness of the biodegradable thermoplastic aliphatic polyester is 1 to 15
A biodegradable root cover for raising seedlings, which is formed of a non-woven fabric in which fibers having a denier and a crystallinity of 20 to 80% are integrated by three-dimensional entanglement. 2. The root cover for biodegradable seedling raising according to claim 1, wherein the constituent fibers are fused by heat treatment on at least one side of the nonwoven fabric to form a porous film. 3. The biodegradable root cover for raising seedlings according to claim 1, wherein the nonwoven fabric is impregnated with a binder resin having biodegradability to form a porous film. 4. A basis weight is formed by a nonwoven fabric of 50 to 300 g / m ^2, and is the tensile strength is 5 kg / 5 cm width or more when converted to the basis weight 100 g / m ^2, air permeability 30~500cc / cm ^The biodegradable root cover for raising seedlings according to any one of claims 1 to 3, which has a water permeability of 0.02 to 0.8 cm / sec. 5. The biodegradable root cover for raising seedlings according to any one of claims 1 to 4, wherein the fibers constituting the non-woven fabric are priming fibers. 6. The thermoplastic aliphatic polyester comprises poly (D-lactic acid), poly (L-lactic acid), D-lactic acid and L-lactic acid.
A polymer selected from the group consisting of a copolymer of lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, and a copolymer of L-lactic acid and hydroxycarboxylic acid, or a blend thereof. The root cover for biodegradable seedling raising according to any one of claims 1 to 5. 7. The thermoplastic aliphatic polyester is a polymer selected from the group consisting of polybutylene succinate, polyethylene succinate, polybutylene adipate and polybutylene sebacate, or those polymers as main repeating units. The biodegradable root cover for raising seedlings according to any one of claims 1 to 5, which is a copolymer or a blend thereof. 8. The thermoplastic aliphatic polyester is a polymer of polycaprolactone or polypropiolactone, a copolymer having these polymers as main repeating units, or a blend thereof. The biodegradable rooting cover for raising seedlings according to any one of claims 1 to 5. 9. The root cover for biodegradable seedling raising according to any one of claims 1 to 8, wherein a crystal nucleating agent is added to the thermoplastic aliphatic polyester. 10. The biodegradable rooting cover for raising seedlings according to claim 1, which is formed into a bag shape by sewing or heat bonding.