JPH0889101A - Agricultural sheet - Google Patents

Abstract

PURPOSE: To obtain an agricultural sheet, excellent in mechanical characteristics such as tear strength, dimensional stability, light transmitting and ventilation barrier properties, water absorption properties and flexibility and naturally degradable by embedding treatment and gentle to the environment. CONSTITUTION: This agricultural sheet is obtained by laminating a nonwoven web layer or layers 2 comprising staple fibers having biodegradability onto one or both surfaces of a nonwoven web layer 1 comprising at least >=50wt.% biodegradable synthetic continuous filaments. Constituent fibers of the nonwoven web layer 1 are mutually partially bonded and constituent fibers in the nonwoven web layer or layers 2 are mutually three-dimensionally interlaced. The constituent fibers in the nonwoven web layer 1 are mutually interlaced with those in the nonwoven web layer or layers 2 and a light transmitting part 3 is formed in the central part in the width direction within the range of 50-80% based on the total area of the agricultural sheet. Furthermore, ventilation barrier parts 4 having a dense structure are formed in both lateral parts of the light transmitting part 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agricultural sheet excellent in mechanical properties, dimensional stability, water absorption, translucency, and air barrier properties, and more specifically, it is composed of biodegradable synthetic fibers and is used in the natural world. The present invention relates to an agricultural sheet that is friendly to the environment and biodegradable by burying treatment.

[0002]

2. Description of the Related Art Conventionally, a spunbond non-woven sheet made of synthetic long fibers, a film sheet made of polyester, polyvinyl or the like has been used as an agricultural sheet stretched in a tunnel shape in greenhouse cultivation or the like. .
These sheets are excellent in terms of uniformity of basis weight and strength. However, spunbonded non-woven sheets are excellent in light-shielding properties, but lack in breathability, and film sheets have problems such as lack of breathability. Further, both the spunbond nonwoven sheet and the film sheet have a problem that the atmospheric temperature inside the sheet rises as the temperature rises, and as a result, the water in the soil in which the seedlings are planted evaporates to cause dew condensation. In addition, since synthetic long-fiber spunbonded non-woven sheets and film sheets generally do not have biodegradability, it is necessary to incinerate them for disposal, and there are problems such as pollution of smoke generated during incineration. It is the actual situation.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to solve such problems, and is excellent in mechanical properties such as tear strength, dimensional stability, translucency, air barrier property, water absorption and flexibility. The purpose of the present invention is to provide an environmentally friendly agricultural sheet that can be naturally decomposed by embedding treatment.

[0004]

In order to solve this problem, the present invention has a biodegradability on one or both sides of a nonwoven web layer A composed of at least 50% by weight of biodegradable synthetic filaments. A non-woven web layer B made of short fibers is laminated, and the constituent fibers of the non-woven web layer A are partially adhered to each other. The non-woven web layer B has three or more constituent fibers. Originally entangled, the constituent fibers of the non-woven web layer A and the constituent fibers of the non-woven web layer B are entangled with each other, and the total area of the agricultural sheet is 50 to 50
A gist of the agricultural sheet is that a light-transmitting portion is formed in a range of 80%, and ventilation-blocking portions having a dense structure are formed on both sides of the light-transmitting portion.

Further, the present invention will be described in detail. The agricultural sheet has an area ratio of 50 to 2 on both sides in the width direction.
The 0% portion has a dense structure in which an agricultural sheet in which the non-woven web layer A and the non-woven web layer B are laminated is placed on a net of 50 mesh or more and subjected to high pressure liquid flow treatment. The area of the central area in the width direction of 50 to 80% is a non-woven web layer having a dense structure formed of a net of 50 mesh or more and a mesh of 25 mesh or less. Placed on a net and subjected to high pressure liquid flow treatment in the range of 50 to 80% of the widthwise center of the non-woven web layer, resulting in voids (holes) in the agricultural sheet.
Are formed to have a light-transmitting structure.

The area ratio of the transparent portion to the entire agricultural sheet is preferably in the range of 50 to 80%. If it is less than 50%, in the winter with short sunshine hours, sufficient sunlight cannot be obtained for growing seedlings planted inside tunnel-shaped agricultural sheets, and if it exceeds 80%, it will not be possible to secure sunlight. Although it is sufficient, the hole part located in the center of the stretched agricultural sheet is located on the side of the tunnel, and as a result, this part is substantially breathable, and the cold air of the agricultural sheet is It is not preferable because it may enter the inside and impair the heat retaining effect in the seat.

Next, the agricultural sheet of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of an agricultural sheet of the present invention, in which 1 is a non-woven web layer A containing biodegradable synthetic long fibers as a main component, and 2 is a non-woven web composed of biodegradable staple fibers. A woven web layer B, in which both non-woven web layers A and B are laminated, subjected to high-pressure liquid flow treatment and integrated to form a light-transmitting portion 3 having a hole in the center in the width direction. ing. Reference numeral 4 denotes a ventilation blocking portion formed on both sides of the light transmitting portion 3 and having a dense structure.

The biodegradable synthetic continuous fiber used in the present invention means a fiber obtained by a conventional spinning method of the thermoplastic polymer described below. The polymer is a biodegradable thermoplastic aliphatic polyester polymer, for example, a polymer composed of polyglycolic acid or polylactic acid such as poly (α-hydroxy acid) or a copolymer thereof. And also poly (ε-caprolactone), poly (ω-hydroxyalkanoates) such as poly (β-propiolactone), poly-3-hydroxypropionate, poly-3-hydroxybutyrate, poly −
3-hydroxycaprolate, poly-3-hydroxyheptanoate, poly-3-hydroxyoctanoate, and poly-3-hydroxyvalerate and poly-
Poly (β, such as copolymerization with 4-hydroxybutyrate
-Hydroxyalkanoate). In addition, as a polycondensation product of glycol and dicarboxylic acid, for example, polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, polybutylene sebacate. , Polyhexamethylene sebacate, polyneopentyl oxalate or copolymers thereof. Further, the aliphatic polyester and polycapramide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyundecanamide (nylon 11), polylaurolactamide (nylon 12). And an aliphatic polyester amide type copolymer which is a copolymer with an aliphatic polyamide.

The long fibers constituting the nonwoven web layer A in the present invention are composed of the above-mentioned polymer having a fiber-forming property and have a single fiber fineness of 2.0 to 10.0 denier. When the monofilament fineness is less than 2.0 denier, the number of constituent fibers of the obtained web is relatively large relative to the basis weight, and the nonwoven fabric structure becomes dense to impair the translucency, which is not preferable. On the other hand, if the monofilament fineness exceeds 10 denier, not only the texture of the obtained web becomes hard and a flexible composite nonwoven fabric cannot be obtained, but also the spinnability in the melt spinning step is deteriorated, which is not preferable. Therefore, in the present invention, the single fiber fineness is preferably in the range of 2.0 to 10.0 denier, more preferably 3.0 to 8.0 denier.

Nonwoven web layer A of the agricultural sheet of the present invention
Is produced by a spunbond method using a polymer selected from the biodegradable thermoplastic resins. That is, melt spinning is performed using one or a plurality of polymers selected from the biodegradable thermoplastic resins. After the yarn spun from the spinneret is cooled by a known cooling device, it is taken up by air sucker, the yarn is opened using a corona discharge device, etc., deposited on a moving deposition device, and then partially heat-bonded. To obtain a spunbonded nonwoven fabric. This partial heat bonding is a web structure of a portion corresponding to the engraved pattern by passing a web between a roll having an engraved pattern engraved on the surface under heating conditions, that is, an embossing roll and a metal roll having a smooth surface. This is done by thermally adhering the fibers together. More specifically, this partial thermal bonding has a certain area relative to the total surface area of the nonwoven web layer A, i.e. the individual thermal bonding areas do not necessarily have a circular shape, 0.1-1.0 mm ²
Has an area of 2 to 80 and its density, that is, the adhesion point density
The point / cm ^{2 is} preferably 4 to 60 points / cm ² . If the bond point density is less than 2 points / cm ² , the mechanical properties and shape retention of the web layer after heat bonding will not be improved, while if the bond point density exceeds 80 points / cm ² , the flexibility will decrease. In addition, the spreadability is inferior and neither is preferable.

The area ratio of the total heat-bonded region to the total surface area of the nonwoven web layer A, that is, the bonded area ratio is 2 to 30%.
It is preferably 4 to 20%. If the bonding area ratio is less than 2%, the dimensional stability of the nonwoven web layer A after heat bonding is not improved, and a composite nonwoven fabric obtained by laminating the nonwoven web layer A on the nonwoven web layer B is obtained. Is inferior in dimensional stability and is not preferable. Further, when the bonded area ratio exceeds 30%, after the non-woven web layer B is laminated, the constituent fibers of the non-woven web layer A and the constituent fibers of the non-woven web layer B act on each other as a entanglement treatment on the high pressure liquid flow. Not only does it not cause a dense entanglement when it is squeezed, but the adhesive area occupying the non-woven web layer A becomes large, and the overlapping portion of the fibers of the adhesive portion increases, so that the agricultural sheet embedded in the soil Is not preferable because it causes a delay in the biodegradation rate of.

The nonwoven web layer A of the present invention preferably has a basis weight of 10 to 40 g / m ² . When the basis weight is less than 10 g / m ² , the degree of dense overlap between long fibers is low, and the formation of a composite non-woven fabric obtained by laminating this non-woven web layer A with a short fiber non-woven web layer B When the basis weight is more than 40 g / m ² , the denseness of the non-woven web layer A increases, and when the non-woven web layer B is laminated and entangled, the non-woven web layers A and B are separated from each other. Not only is the entanglement property deteriorated, but also it becomes difficult to impart pore shapes to the composite non-woven fabric, and the translucency is impaired. Therefore, in the present invention, the basis weight of the nonwoven web layer A is 10 to 40 g / m.
^{2 It is} preferably 15 to 30 g / m ² .

In the present invention, the biodegradable synthetic continuous fiber which is the main component of the nonwoven web layer A is contained in an amount of 50% by weight or more. By containing 50% by weight or more of this biodegradable synthetic long fiber, when the agricultural sheet is buried in the soil,
The biodegradable synthetic long fibers which are the constituent fibers of the non-woven web layer A are biodegraded, whereby only the entanglement between the constituent fibers of the non-woven web layer A and the constituent fibers of the short fibrous non-woven web layer B is separated. In addition, the entanglement between the constituent fibers of the short fiber non-woven web layer B becomes weak, the fibers forming the short fiber non-woven web layer B are individually separated, and the rate of biodegradability is promoted. If this biodegradable synthetic long fiber is less than 50% by weight, the three-dimensional entanglement between the short fibers becomes strong due to the increase in the short fibers constituting the agricultural sheet, and thus it is used for agricultural treatment buried in the soil. Even if the biodegradable synthetic long fibers of the non-woven web layer A of the sheet are decomposed, the constituent fibers of the short fiber non-woven web layer B remain entangled, resulting in a slower biodegradation rate of the entire agricultural sheet. Not preferable.

Further, in the present invention, as the biodegradable short fibers constituting the non-woven web layer B, those obtained by cutting the biodegradable synthetic long fibers as described above into a predetermined length, and cotton. Cellulose fibers such as ramie, recycled fiber pulp such as rayon, cotton and the like can be used.

As the cotton, in addition to the combed yarn which has not been subjected to the bleaching treatment and the cotton which has been subjected to the bleaching treatment, it is possible to use a fluff obtained from a cotton yarn, a knitted fabric or a woven fabric. The fluff includes bleached and dyed ones.

The anti-hairing machine which can effectively obtain the anti-hairing in the present invention is a rag machine, a knot breaker, a garnet machine, a slicing machine and the like. The type and combination of anti-fluffing machines used depend on the shape of the fabric to be fluffed, the thickness of the threads that make up it, and the strength of the twist, but several identical anti-fluffing machines can be connected in series or two types can be used. It is effective to use a combination of the above anti-fluffing machines. Here, the defibration rate by the fluffing machine is preferably in the range of 30 to 95%. When the defibration rate is less than 30%, the high-pressure liquid stream does not penetrate the web when the web is entangled with the high-pressure liquid stream, which is not preferable. Further, if it exceeds 95%, sufficient surface abrasion strength cannot be obtained, which is not preferable. The defibration rate of the fluff is obtained by the formula shown below. Disentanglement rate (%) = (weight of fluff-weight of filamentous material) × 100 / weight of fluff

The cotton fibers constituting the short fiber non-woven web layer B of the agricultural sheet of the present invention have an average fineness of 1.0.
Denier or more, less than 2.5 denier, average fiber length 15m
Fibers of m or more and less than 35 mm are used.

As the regenerated fiber used in the present invention, viscose rayon, cellulose acetate fiber, and other solution-spun rayon such as lyocell and pulp can be used.

The short fiber made of the biodegradable thermoplastic polymer of the present invention can be efficiently produced by the following steps. That is, melt-spinning is performed with a spinning die using a biodegradable polymer, the spun yarn is cooled, and then undrawn yarn is drawn at a speed of 800 to 1200 m / min.

A plurality of the obtained undrawn yarns are combined to form an undrawn yarn bundle, which is subjected to a drawing treatment using a two-stage drawing machine. During the drawing treatment, the breaking elongation of the undrawn yarn is 70 to
A target draw ratio in the range of 95% is set. At the time of stretching, in the first stage stretching treatment, the target stretching ratio of 70
The target stretching ratio is achieved by performing stretching of 85% and then performing the second stage stretching treatment. The drawn yarn is heat-set by a heat roll, crimped by an indenting crimper, and an oil agent for spinning is applied, followed by a drying treatment to obtain a single yarn of the yarn. It is cut into a predetermined fiber length according to the fineness. The number of crimps applied by the indentation crimper is preferably 12 to 25 threads / 25 mm. The crimped fiber bundle is applied with a spinning oil, dried and then cut into a predetermined fiber length according to the fineness of the single yarn of the fiber bundle.

In the present invention, the short web non-woven web layer B
Is to be opened using a card machine, but the card machine to be used is selected from a parallel card machine, a random card machine, and a semi-random card machine depending on the performance required for the composite nonwoven fabric. To be done. Further, a cross layer may be arranged on a parallel card machine, or a cross laid non-woven web may be used with a drafter to change the vertical / horizontal arrangement of the webs.

As the synthetic fibers constituting the biodegradable short fiber non-woven web layer B of the agricultural sheet of the present invention, those having a fineness of 1.0 to 5.0 denier and a fiber length of about 10 to 76 mm are used. Adopt it. When the fineness is less than 1.0 denier, the number of fibers constituting the short fiber non-woven web layer B increases, making it difficult to give a mesh pattern, and 5.0
When the denier is exceeded, the number of fibers constituting the short fiber non-woven web B becomes small, so that it is not preferable because the translucency cannot be obtained.

The short fiber non-woven web layer B in the present invention is
The basis weight is preferably ²⁰ to 150 g / m ² . When the basis weight is less than 20 g / m ² , not only the shape retention of the obtained nonwoven web layer B is not improved, but also the light-shielding property is not sufficiently retained, which is not preferable. Further, when the basis weight exceeds 150 g / m ² , the energy at the time of high-pressure liquid flow treatment becomes large, and in extreme cases, the nonwoven web layer B
In the inner layer, the short fibers are not entangled with each other, and as a result, practical mechanical properties cannot be obtained, which is not preferable. In addition, the mesh pattern applied to the nonwoven web layer B becomes unclear, resulting in a nonwoven web layer B having no voids in the air-permeable portion, which is not preferable because good air permeability cannot be obtained. For the above reasons, the basis weight of the nonwoven web layer B is 20
To 150 g / m ² , more preferably 50 to
It is in the range of 100 g / m ² .

The first feature of the present invention is that, as the non-woven web layer A, a biodegradable synthetic long fiber non-woven web obtained by melt spinning a polymer having biodegradability and obtained by a spunbond method is used. is there. Further, as the short fiber non-woven web layer B laminated on the non-woven web layer A, a biodegradable short fiber non-woven web is used.

A second feature of the present invention is that a high-pressure liquid flow is applied from the side of the short fiber non-woven web layer B, the fibers constituting the short fiber non-woven web layer B are three-dimensionally entangled, and This is because the fibers constituting the degradable synthetic long-fiber nonwoven web layer A and the fibers constituting the short-fiber non-woven web layer B have a three-dimensional entanglement.

In the present invention, the term "three-dimensional entanglement" means that the fibers forming the short fiber non-woven web layer B are entangled not only in the longitudinal and transverse directions but also in the thickness direction to be closely integrated, It means that the constituent fibers of the fibrous non-woven web layer B and the constituent fibers of the biodegradable synthetic long-fiber non-woven web layer A are closely integrated with each other.

The agricultural sheet of the present invention can be efficiently produced by the following steps. That is, in the agricultural sheet of the present invention, a carded and opened short fiber nonwoven web layer B is added to a biodegradable synthetic long fiber nonwoven web layer A obtained by a spunbond method using the polymer. The short fiber non-woven web layer B is laminated, and a high-pressure liquid flow is applied from the side of the short fiber non-woven web layer B so that the fibers constituting the short fiber non-woven web layer B are three-dimensionally entangled with each other and the biodegradable synthetic long fiber non-woven web layer is formed. The fibers constituting A and the fibers constituting the short fiber nonwoven web layer B are three-dimensionally entangled with each other.

This step will be described in more detail. Pore size 0.0
Using an orifice head in which a plurality of injection holes of 5 to 1.5 mm are arranged in one row or a plurality of rows with an injection hole interval of 0.5 to 5 mm, a high-pressure liquid stream that is ejected in a columnar shape at high pressure is jetted onto a net. The composite non-woven fabric in which the short fiber non-woven web layer B is laminated on top of the biodegradable synthetic long fiber non-woven web layer A is caused to act, and the fibers constituting the short fiber non-woven web layer B are closely entangled with each other. The constituent fibers of the biodegradable synthetic long-fiber non-woven web layer A and the constituent fibers of the short-fiber non-woven web layer B are closely integrated. As the liquid, it is preferable to use water at room temperature or hot water from the viewpoint of economy.
When the high-pressure liquid stream is collided with the composite nonwoven fabric,
While oscillating the orifice head provided with the injection holes in a direction perpendicular to the traveling direction of the composite nonwoven fabric placed on the net at the same intervals as the injection hole intervals, the high pressure liquid flow is injected. It is good to make them collide uniformly.

The net used for jetting the high-pressure liquid stream may be made of metal, polyester, or any other material as long as the high-pressure liquid stream can pass through the composite nonwoven fabric.

In the present invention, the net for forming the ventilation blocking portion in the composite non-woven fabric is 50 to 15
The one with 0 mesh is used. If the net is less than 50 mesh, pores are formed on the surface of the entangled composite non-woven fabric, and it is not possible to maintain sufficient air permeability, which is not preferable. Further, if it exceeds 150 meshes, a sufficient ventilation blocking property can be maintained, but the energy cost required for the high pressure liquid flow treatment becomes large, which is not preferable.

The high pressure liquid flow treatment is preferably performed at least twice. That is, in the first high-pressure liquid flow treatment, the composite nonwoven fabric is pre-entangled with the high-pressure liquid flow having a water pressure of 40 kg / cm ² G or less. When the water pressure at the time of performing the first entanglement treatment exceeds 40 kg / cm ² G, the short-fiber non-woven web layer B is disturbed due to the accompanying airflow generated by the high-pressure liquid flow, and uneven weight is generated.
It is not preferable in maintaining the quality of the non-woven fabric.

The composite non-woven fabric is subsequently subjected to the second and subsequent entanglement treatments with a high-pressure liquid flow having a water pressure of 50 kg / cm ² G or more, whereby the short fibers are three-dimensionally and densely integrated and biodegraded. Synthetic long-fiber non-woven web layer A
It is possible to obtain a composite non-woven fabric in which the constituent fibers and the constituent fibers of the short fiber non-woven web layer B are closely integrated.

A third feature of the present invention is that in a so-called spunlaced nonwoven fabric having a three-dimensional entanglement, the composition of the entanglement of the surface of the nonwoven fabric is composed of a portion having a dense surface constitution and a portion having a hole shape. Especially.

That is, when processed into an agricultural sheet, the portion having the holes is located in the center in the sheet width direction and has a light-transmitting property, and the portions having a dense structure are located on both sides of the sheet. It has a ventilation blocking property.

Next, the formation of the portion having the function of transmitting light of the agricultural sheet of the present invention will be described in detail. Guide the composite non-woven fabric that has been subjected to high-pressure liquid flow treatment using a net of 50 mesh or more onto the net of 25 mesh or less, and to the center of the composite non-woven fabric that has been subjected to high-pressure liquid flow treatment using a net of 50 mesh or more. The high-pressure liquid flow is acted again to give the composite non-woven fabric the pore shape of the net of 25 mesh or less to form a translucent portion.

The formation of the light-transmitting portion by the net of 25 mesh or less will be described in more detail. On the upper part of the composite nonwoven fabric placed on the net of 25 mesh or less, injection holes having a diameter of 0.05 to 1.5 mm are formed. By arranging a plurality of movable orifice heads each having a width of 50 to 100 cm and arranged at intervals of 0.5 to 5 mm, and adjusting the arrangement angle and the arrangement position of the orifice heads, the position and width of the hole shape are given. Is regulated and the shape of the pores is imparted, whereby a composite non-woven fabric having a substantially perforated portion is constituted. The liquid pressure required for jetting the high-pressure liquid flow in this step is not intended for the entanglement treatment, but may be any liquid pressure capable of imparting pore shapes, and is appropriately selected depending on the basis weight of the composite nonwoven fabric.

The excess moisture of the composite non-woven fabric obtained as described above is removed by a known moisture removing device such as mangle, and further dried by using a suction band type hot air circulation dryer, and three-dimensionally entangled. And a composite non-woven fabric having a partial pore shape is obtained.

The agricultural sheet made of the composite non-woven fabric obtained by the above-mentioned method comprises the constituent fibers of the short fiber non-woven web layer B and the constituent fibers of the biodegradable synthetic long fiber non-woven web layer A by the action of the high pressure liquid flow. A three-dimensional entanglement occurs between them and a hole shape is given, so that the non-woven web of the long-fiber non-woven web obtained by the spunbond method has an original uniform and dense structure, and the partial fiber movement and heat Due to the separation of the constituent fibers of the bonded part, when it is buried in the soil, biodegradation is further promoted.

After the above steps, the agricultural sheet of the present invention may be post-processed such as printing or dyeing, or may be provided with a resin on one side or both sides of the sheet, if necessary, so as to retain its shape and repellent property. It is also possible to add water.

[0040]

Embodiments of the present invention will be described below. The measurement of the examples in the present invention was performed by the following method. (1) Melt flow rate; ASTM D1238
It was measured by the method described in (L).

(2) Melting point of polymer: Using DSC-2 type differential scanning calorimeter manufactured by Perkin Elmer Co., a sample amount of about 5 m
The melting point was defined as the temperature at which the maximum value of the melting and absorption heat peak was measured at a heating rate of 20 ° C./min.

(3) Tensile strength of non-woven fabric (kg / 5cm
Width); using a constant speed extension type tensile tester (Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co., Ltd.), JIS
It was measured according to the strip method described in L-1096.
That is, 10 sample pieces having a sample width of 5 cm and a sample length of 15 cm were prepared, and the maximum tensile strength (kg) was obtained by measuring each sample at a gripping interval of 10 cm and a tensile speed of 10 cm / min. The average value of the tensile strength values was defined as the tensile strength (kg / 5 cm width) of the nonwoven fabric.

(4) Compressive stiffness (g); sample length 10c
A total of 5 sample pieces each having m and a sample width of 5 cm were prepared, and each sample piece was bent in the lateral direction to form a cylindrical object, and its end portions were joined to each other to obtain a sample for measuring compression stiffness. Then, a constant speed extension type tensile tester (Tensilon UTM-4-1-manufactured by Toyo Baldwin Co., Ltd.) is used for each measurement sample in the axial direction.
100) was used for compression at a compression rate of 5 cm / min, and the average value of the maximum load values (g) obtained was taken as the compression stiffness (g).

(5) Ventilation blocking property (m / sec): Five 30 cm square samples were prepared, and a wind generator with a wind speed of 10 m / sec and a wind speed measuring instrument model 6621 manufactured by Japan Canomax Co., Ltd. were used as a measuring instrument. It was measured using. That is, the sample wind speed is 7 m
The sample was placed vertically at a wind speed of / sec, the wind speed passing through the sample was measured for each sample at a position 1 cm immediately after the sample, and the average value was taken as the air permeability (m / sec).

(6) Translucency (Look): Five 30 cm square samples were prepared, and 200 W white light was used as a light source.
Illuminance meter ANA-3 manufactured by Tokyo Kodensha Co., Ltd.
00 was used for measurement. That is, the distance between the light source and the measuring device is set at 2000 lux, the sample is placed horizontally at 10 cm above the measuring device, the amount of light passing through the sample is measured for each sample, and the average value is taken as the light-shielding property (lux). did.

(7) Water absorption (cm / 10 minutes); JIS L
By the Bayrec method described in -1096, width 2.5c
5 samples of m and 20 cm in length are prepared, and 20 pieces of each sample piece are prepared.
Hang it with a pin on a horizontal bar supported at a certain height above a tank containing distilled water at ± 2 ° C. Align the lower end of the sample piece in a line and lower the horizontal bar so that 1 cm of the lower end of the sample piece is just submerged in water. Next, the elevated height (mm) of water after standing for 10 minutes was measured, and the average value was taken as water absorption (cm / 10 minutes).

(8) Biodegradability: A sample of 30 cm × 30 cm was embedded in soil, taken out after 3 weeks, and the shape of the nonwoven fabric was visually evaluated to evaluate. In addition, for those that retain the morphology of the nonwoven fabric, the strength of the nonwoven fabric was measured, and those showing a measured value that was 50% or more lower than the initial strength were judged to have good biodegradability.

Example 1 A synthetic long fiber non-woven web layer A was produced by a spunbond method using polybutylene succinate having a melting point of 116 ° C., a density of 1.15 g / cc and a melt flow rate of 30 g / 10. The non-woven web layer A thus obtained has a monofilament fineness of 2.
It was 5 denier. Then, the obtained web was subjected to a heat pressing treatment to obtain a nonwoven web layer A having a basis weight of 20 g / m ² . The area is 0.36mm when applying the heat pressure welding process.
^The embossing roll in which the engraving pattern ² was arranged at a pressure contact density of 40 points / cm ² and a pressure contact area ratio of 15% and a metal roll having a smooth surface were used. The surface temperature of the embossing roll and the metal roll having a smooth surface was 100 ° C., and the linear pressure between both rolls was 10 kg / cm.

As the short fiber non-woven web, a fineness of 2 denier and a fiber length of 5 obtained by polybutylene succinate are used.
1 mm short fibers were used. Using a random card machine, a short fiber non-woven web layer B having a basis weight of 60 g / m ^{2 and} a random fiber arrangement was obtained.

The short fiber non-woven web layer B thus obtained is laminated on one side of the synthetic long fiber non-woven web layer A, and the short fiber non-woven web layer B is placed on a 70 mesh net which moves at 20 m / min. Placed as the upper layer and above the short fiber non-woven web layer B 50
At the position of mm, the first treatment was performed from the liquid flow injection holes arranged with the hole diameter of 0.12 mm and the hole spacing of 0.6 mm, and the high-pressure liquid flow treatment was performed with normal temperature water with a water pressure of 40 kg / m ² G. Subsequently, as the second treatment, the same high-pressure liquid flow treatment was carried out four times with a water pressure of 70 kg / m ² G using the same net and injection holes as described above.

The obtained non-woven fabric was dried with a drier at a temperature of 80 ° C. after removing excess water by mangle. The obtained non-woven fabric has a basis weight of 82 g / m ^2.
The constituent fibers were densely integrated with each other, and the constituent fibers of the short fiber non-woven web layer B were densely integrated with each other to have a three-dimensional entanglement.

The composite non-woven fabric obtained by the above method was cut into 120 cm in the width direction, and was further guided onto a 20-mesh net. At a position 50 mm above the net, the injection holes had a hole diameter of 0.1 mm and an injection hole interval. The center of a 100 cm wide orifice head having 0.6 mm injection holes was aligned with the center of the composite non-woven fabric, and the orifice head was installed at an angle at which the high pressure liquid flow hits the width of 80 cm with respect to the width direction of the composite non-woven fabric.

After removing excess water of the obtained non-woven sheet by mangle or the like, it was dried at a temperature of 80 ° C. by a suction band type drier. The performance of the obtained non-woven sheet is such that the tensile strength of the entangled portion of 70 mesh is 15.2 kg / 5 cm width, and the tensile strength of the portion perforated by 20 mesh is 14 to keep the transparency. The width was 0.6 kg / 5 cm.

In addition, the perforated portion of 20 mesh has a light-transmitting property with clear voids appearing on the surface of the non-woven sheet, and the 70-mesh portion constitutes a dense non-woven sheet and has a ventilation blocking property. Was to be composed.

This non-woven fabric was cut into a size of 30 cm × 30 cm, embedded in soil for 3 weeks, and then taken out. As a result, the form of the non-woven fabric was partially impaired. 4.56, 75% lower initial strength
The width was kg / 5 cm, and the nonwoven fabric had good biodegradability.

Example 2 The synthetic continuous fiber non-woven web layer of Example 1 was used as the synthetic growth fiber non-woven web layer. Separately, as a short fiber non-woven web layer, cotton bleached cotton (average fineness of 1.8 denier, average fiber length) was used. 26m
A composite non-woven fabric was prepared under the same conditions as in Example 1 except that a short fiber non-woven web having a basis weight of 25 g / m ^{2 with} a non-uniform fiber arrangement was used with a random card machine.

Comparative Example 1 Example 1 except that polyester staple fibers manufactured by Nippon Ester Co., Ltd. (trade name: 101, fineness: 2 denier, fiber length: 51 mm) were used as the staple fibers in the staple fiber nonwoven web. A composite non-woven fabric was prepared under the same conditions as above.

The results obtained by measuring the tensile strength, compressive stiffness and softness, translucency, ventilation barrier property, and water absorbency of the non-woven fabrics in the above-mentioned Examples and Comparative Examples are shown in Table 1, and the biodegradability evaluation results are shown in Table 1. 2 shows.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

Industrial Applicability As described above, according to the present invention, mechanical properties such as tensile strength, dimensional stability, translucency, ventilation blocking property, and water absorption are excellent, and biodegradation enables composting. It is possible to provide a material suitable as a simple agricultural sheet. In particular, the present invention is excellent as an agricultural sheet in which a light-transmitting portion having a hole shape is formed in the center in the width direction, and ventilation blocking portions having a dense structure are formed on both sides of this light-transmitting portion. The non-woven structure that is effective and has a precise structure
It stabilizes the shape of the entire sheet, and has excellent malleability in combination with the flexibility obtained by three-dimensional entanglement.

[Brief description of drawings]

FIG. 1 is a perspective view of an agricultural sheet of the present invention.

[Explanation of symbols]

 1 Biodegradable synthetic long-fiber non-woven web layer A 2 Short-fiber non-woven web layer B 3 Light transmitting part 4 Ventilation blocking part

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 19, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction content]

Example 1 A synthetic long fiber non-woven web layer A was produced by a spunbond method using polybutylene succinate having a melting point of 116 ° C., a density of 1.15 g / cc and a melt flow rate of 30 g / 10. The non-woven web layer A thus obtained has a monofilament fineness of 2.
It was 5 denier. Then, the obtained web was subjected to a heat pressing treatment to obtain a nonwoven web layer A having a basis weight of 40 g / m ² . The area is 0.36mm when applying the heat pressure welding process.
^The embossing roll in which the engraving pattern ² was arranged at a pressure contact density of 40 points / cm ² and a pressure contact area ratio of 15% and a metal roll having a smooth surface were used. The surface temperature of the embossing roll and the metal roll having a smooth surface was 100 ° C., and the linear pressure between both rolls was 10 kg / cm.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

As the short fiber non-woven web, a fineness of 2 denier and a fiber length of 5 obtained by polybutylene succinate are used.
1 mm short fibers were used. Using a random card machine, a short fiber non-woven web layer B having a basis weight of 30 g / m ^{2 and} a random fiber arrangement was obtained.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction content]

The obtained non-woven fabric was dried with a drier at a temperature of 80 ° C. after removing excess water by mangle. The resulting nonwoven fabric has a basis weight of 68 g / m ^2.
The constituent fibers were densely integrated with each other, and the constituent fibers of the short fiber non-woven web layer B were densely integrated with each other to have a three-dimensional entanglement.

Claims (1)

[Claims] 1. A non-woven web layer A comprising at least 50% by weight of biodegradable synthetic filaments on one or both sides,
A non-woven web layer B made of laminated biodegradable short fibers, wherein the constituent fibers of the non-woven web layer A are partially adhered to each other.
The constituent fibers are entangled three-dimensionally, the constituent fibers of the non-woven web layer A and the constituent fibers of the non-woven web layer B are entangled with each other, and the total area of the agricultural sheet is 50 at the center in the width direction.
A light-transmitting portion is formed in a range of ˜80%, and a ventilation blocking portion having a dense structure is formed on both sides of the light-transmitting portion.