JP2021073968A - Uncrosslinked elastomer weed control sheet composition and weed control sheet as well as construction method thereof - Google Patents

Abstract

To provide: material compositions that are semi-permanently resistant to deterioration by ultraviolet rays; weed control sheet products that semi-permanently maintain a weed controlling function; and weed control sheet construction methods that solve the problem of rainwater drainage at a sheet construction site by the drainage management of an entire sheet construction.SOLUTION: There are provided: an uncrosslinked elastomer weed control sheet composition that is an uncrosslinked elastomer composition containing 15 to 25 wt.% of EPDM (ethylene-propylene-diene Methylene linkage) with respect to an elastomer composition, 30 to 45 wt.% of a carbon black, and 7 to 10 wt.% of a polyethylene resin with a density of 890 to 920 kg/cubic meter, the total content of a sulfur-based crosslinking accelerator and sulfur being 0.001 wt.% or less, and the aroma component in an oil component being 0.001 wt.% or less; and a weed control sheet product thereof.SELECTED DRAWING: Figure 1

Description

The present invention relates to a composition of a weed-proof sheet for suppressing the growth of weeds, a product thereof, and a construction method thereof.

Weeds are vibrant grasses that grow anywhere with soil, water and light. In order to suppress the growth of the weeds, it is possible if any of these three elements can be completely eliminated. Generally, products commercialized for the purpose of suppressing the growth of weeds by blocking light are called weed control sheets or weed control sheets. There are two types, one that can be used in a bare state and the other that is exclusively for under gravel, but no bare type product has a durability of more than 10 years.

When weed control sheet construction is carried out on a large scale, for example, in the case of a solar power plant, even a small property will be several thousand square meters, and if rainwater on the upstream side of the site flows to the downstream side, it will cause flood damage to neighboring land. Therefore, drainage and water permeability are required for the weed-proof floor on which the weed-proof sheet is installed. This has a trade-off relationship with the weed control function of blocking light and suppressing the growth of grass. Therefore, in the bare type, there has been no sheet that completely suppresses the growth of grass for a long period of time.
In the gravel-laying type, soil is piled up on it and grass grows from it, so even with this construction method, it was not possible to prevent the growth of grass for a long period of time.

In order to achieve both the trade-off (drainage property and weed control function), a 4-layer spunbonded non-woven fabric made of polypropylene resin has been commercialized. However, polypropylene resin has a tertiary carbon in its molecular structure, and this carbon is easily photodegraded. This resin is a disintegrating resin, and an ultraviolet absorber is added as a light resistance stabilizer. However, it was impossible to make it durable for more than 10 years.

Construction of weed control sheets requires on-site surveys, weeding, soil removal, environmental assessment of wastewater, and explanations to surrounding land owners. In addition to the material cost and construction cost of the weed control sheet, the weeding work cost at the site and its disposal cost are also required. When constructed with inexpensive materials, the weed-proof sheet deteriorates to pieces in a few years, and weeds such as Imperata cylindrica, Equisetum arvense, and Gramineae, which have strong vigor, break through the deteriorated weed-proof sheet and before construction of the weed-proof sheet. It reverts to the state where weeds grow. There has been no material, weed-proof sheet product, or sheet construction method that maintains the weed-proof function for at least 20 years.

There is also a method of laying concrete crushed material for the purpose of weed control, but the land cannot be regenerated, the soil covers the surface after a while, and the water permeability is insufficient, causing flood damage to the surrounding land. There is. In addition, although rubber-based weed control sheets were also applied, there was a concern that soil would be contaminated because the products so far had a strange odor and the added oil and cross-linking agent were carcinogens. ..

As the material of the weed-proof sheet, a non-woven fabric of polyethylene resin or polypropylene resin is used. The reason is that it is inexpensive and the sheet strength is high. However, these olefin-based resin sheets are easily deteriorated by ultraviolet rays, deteriorate in several years, and have a significantly reduced weed control function.

Patent No. 4744402 Patent application 2006-241997 Patent No. 6319835 Patent No. 5430688

The land where weeds grow is uneven, and roots remain even after mowing, so even if you cover it with an existing weed control sheet, a gap will be created between the land and the sheet, and it will fall. Sunlight cannot be completely blocked. Grassroots visits are often not carried out due to high construction costs. The thickness of the existing weed-proof sheet is about 1 mm, and since it is made of resin, the sheet does not stretch at all, so that it cannot be in close contact with the uneven soil surface. Furthermore, because it is thin and light, it is extremely difficult to construct a weed-proof sheet on a windy day, which is one of the causes of high construction cost. The material of the sheet is polyethylene resin or polypropylene resin. In fact, these are resins having poor light resistance, and there has been no product that retains the weed-proof function for 10 years or more in the bare type that is constantly exposed to ultraviolet rays.

Provided is a sheet that can be covered with a sheet over uneven land and a stump of grass generated by mowing, and has an elongation property that adheres to the surface of the land. In addition, the weight to crush the grass, the weight that does not become like a kite due to the wind at the time of construction, and the weight (specific weight) that is optimal for manual work, maintains the weed control function for 20 years, and the fence. We provide a sheet construction method that has excellent sheet cutability and solves the problem of drainage of rainwater that has poured onto the construction site so that it can be easily processed around the concrete foundation and its boundary.

As a result of diligent studies on the above problems, the inventor has found that the problem can be solved by inventing the design of the weed-proof sheet composition and the product form of the weed-proof sheet product, and the construction method thereof.
Ultraviolet rays contained in sunlight have the energy to destroy the molecular structure of resin materials. Stabilizers have the function of preventing the autoxidation reaction by supplementing the generated radicals, and the addition of UV absorbers has been established as a technique for preventing UV deterioration of resins. However, since this compound is difficult to stay in the material due to volatilization or bleeding out during long-term exposure of the material, the function of the chemical alone is more than 10 years in sunlight. At present, it is not possible to prevent product deterioration.

In order to obtain a composition that does not deteriorate with ultraviolet rays for at least 20 years, EPDM (ethylene / propylene / diene copolymer) rubber, which is an olefin-based material that is not easily photodegraded, has an elastomer composition weight ratio of 15 to 25% by weight. .. If it is lower than 15% by weight, the strength of the sheet is lowered, which is not preferable. If it is larger than 25% by weight, the cost of the composition becomes high and it is not accepted in the market. The material that completely blocks ultraviolet rays is carbon black. When this content is 30 to 45% by weight, the infiltration of ultraviolet rays into the elastomer composition can be completely blocked. If it is lower than 30% by weight, ultraviolet deterioration progresses. If it is larger than 45% by weight, the carbon black cannot be dispersed in the EPDM rubber by the rubber kneader, which is not preferable.

In order to develop the weed control function, mechanical strength is required to counter the force of pushing up from below due to the growth of grass. Specifically, sheet strength and sheet elongation are required. As a result of diligent studies, in order to develop this sheet strength and stretchable physical properties, it is optimal that the polyethylene resin resin having a density of 890 to 920 kg / cubic meter is 7 to 10% by weight, and the uncrosslinked elastomer composition is 2 mm. As a result of the test on the thickness sheet, the tension strength is 2 MPa or more and the elongation is 30% or more. If it is lower than 7% by weight, the mechanical strength as a weed control function is not exhibited. If it is more than 10% by weight, the polyethylene resin resin cannot be dispersed in the EPDM rubber, the rubber kneading processability deteriorates, and an uncrosslinked elastomer composition cannot be obtained, which is not preferable.

The seat specific density is 1150 to 1350 kg / cubic meter. If it is lower than 1150 kg / cubic meter, the force to hold down the grass is reduced and the weed control function is not exhibited. If it is heavier than 1350 kg / cubic meter, workability at the time of sheet construction deteriorates, which is not preferable. The sheet hardness is 60 to 80, preferably 70 to 78, in terms of JISA hardness. If it is softer than 60, it cannot compete with the vigor of the grass from below, which is not preferable. If it is larger than 80, the handling property of the sheet, specifically, the deployability of the sheet at the time of sheet construction is deteriorated, which is not preferable.

The sheet thickness is 2.0 mm to 6.6 mm, preferably 2.6 mm to 5.6 mm, and the width thereof is 39 cm to 91 cm. If the sheet thickness is thinner than 2.0 mm, the weight for crushing the grass per unit area is insufficient, which is not preferable. If it is larger than 6.6 mm, the sheet workability deteriorates, which is not preferable. If the sheet width is smaller than 39 cm, the number of times of laying increases with respect to the target construction area, which deteriorates the sheet construction workability, which is not preferable. If it is larger than 91 cm, the weight of the seat becomes heavy and it is out of the category of manual work, which is not preferable.

In this composition, the total content of the sulfur-based cross-linking accelerator suspected to be carcinogenic and sulfur is 0.001% by weight or less. Further, the oil component has an aroma component of 0.001% by weight or less.

The sheet of the present invention has no holes through which water can pass because it completely blocks light so as to continue to exert the weed-proof function, and the sheet has a thickness of 4 to 5 times that of the existing sheet. The problem of drainage in the construction of the waterproof sheet can be solved by the sheet construction method of the present invention.
FIG. 1 shows a sheet construction method. Specifically, the sheets are laid so that the lengths of 2 cm to 6 cm from the edge of the sheet overlap. FIG. 2 shows a sheet holding method and a rainwater drainage method. Concave diggings are made in the ground at least at intervals of 5 m, a sheet is constructed according to the dents, and the sheet is pressed with gravel or the like so as to have a thickness of 5 cm or more from above. FIG. 3 shows a drainage treatment method for rainwater on the entire sheet construction surface. This is a construction method in which at least one resin pipe having a diameter of 3 cm or more is pierced into the recessed portion, and rainwater or the like collected in the recessed portion is discharged to the ground. As shown in FIG. 1, by stacking the sheets, a step of 2.6 mm to 5.6 mm, which is the sheet thickness, is formed. Rainwater can penetrate the ground from the overlapping portion of this step portion. The invention of the construction method shown in FIG. 2 completely blocks sunlight by the weed-proof sheet of the present invention, thus maintaining the weed-proof function for 20 years, and the invention of the present construction method drains the entire sheet construction surface. Can also solve the problem of.

Since the weed-proof sheet of the present invention contains 30% by weight or more of carbon black and is an EPDM composition having excellent light resistance, it does not deteriorate semipermanently with the ultraviolet rays of sunlight. In addition, since it can completely block sunlight from the ground, it exerts a semi-permanent weed control effect even if it is a bare type.

Regarding the drainage performance of the sheet, which has a trade-off relationship with the weed-proof function, the problem of drainage can be solved by the construction method of the weed-proof sheet of the present invention.

In addition, the rubber elasticity makes the sheet completely adhere to the ground so that it can withstand heavy rain and strong winds when a typhoon hits. In addition, it can be applied to inclined parts such as slopes, and since no aroma component or sulfur component is added to the sheet composition, it is a highly environmentally safe sheet that can be used for environmental assessment. ..

Construction method of weed-proof sheet of the present invention Rainwater drainage construction method for the entire construction surface of the weed-proof sheet of the present invention Sheet holding method of weed-proof sheet and construction schematic diagram of gravel and drainage pipe

Non-crosslinked elastomer composition The material that can maintain the mechanical strength of the sheet when exposed to sunlight for 20 years is EPDM (ethylene / propylene / diene copolymer rubber), and this EPDM is the elastomer composition. It is 15 to 25% by weight and the content of carbon black for rubber is 30 to 45% by weight.

Any grade can be applied as long as it is carbon black for rubber. Any polyethylene resin with a density of 890 to 920 kg / cubic meter can be used regardless of grade. When the present resin is 7 to 10% by weight with respect to 100 parts by weight of the elastomer composition, rubber elasticity is exhibited even if it is not crosslinked. The tensile strength of the 2 mm sheet of the uncrosslinked elastomer composition is 2 MPa or more, preferably 3 MPa or more. The force can be maintained for 20 years by receiving the force pressed by the holding pin, pile, etc. of the weed-proof sheet.
The seat specific gravity is 1150 to 1350 kg / cubic meter, and the seat can be easily constructed without being disturbed by the wind during construction. As a weed control function, the thickness of the sheet is extremely important, and the thickness that can completely block light and resist the tearing of the grass stump with the sheet is 2.0 mm to 6.6 mm, preferably 2.6 mm. It is 5.5 mm. If it is thinner than 2 mm, it may be pierced by the tip of the stump, which is not preferable. The sheet hardness is 60 to 80 in JISA hardness. If the hardness is softer than 60, the force to crush the grass decreases, which is not preferable. If it is larger than 80, the sheet is hard, so that the sheet deployability at the time of constructing the sheet is deteriorated, and the construction cost is high, which is not preferable. The width of the sheet is 39 cm to 91 cm, and if it is this width, the handleability when manually constructing is good. The total content of the sulfur-based cross-linking accelerator and sulfur, which are suspected to be carcinogens, is 0.001% by weight or less, and the aroma component in the oil component is 0.001% by weight or less. Soil will not be contaminated by rainwater after sheet construction.

Product form of weed-proof sheet Since the weed-proof sheet of the present invention has a high specific density and a large thickness, roll winding, which is a normal product form of a weed-proof sheet, is not suitable. Fold it flat on the pallet and adjust the stacking height so that the height is less than 1 m. The sheet can be easily constructed by transporting it to the construction site together with this pallet, pulling out the sheet from above in parallel with the longitudinal direction of the sheet, and constructing it on the land.

Construction method of weed-proof sheet The weed-proof sheet itself has no water permeability. The function corresponding to the water permeability required for the weed-proof sheet is constructed by the method shown in FIG. That is, it is laid so as to overlap 2 to 6 cm from the edge of the sheet of the present invention, preferably 3 cm to 4 cm. Rainwater can be drained to the ground from the overlapping part of the sheets.
FIG. 2 shows a sheet construction method for the drainage groove and the seat holding portion at the construction site. The groove portion obtained by laying a sheet according to the shape of the recessed portion of the land and laying gravel on the portion by 5 cm or more has a function of treating on-site rainwater and a function of suppressing the sheet.
In FIG. 3, a resin pipe having a diameter of 3 cm or more, preferably a vinyl chloride pipe, is pierced into the groove portion to easily drain the rainwater collected in the groove to the ground. By this construction method, the sheet is constructed so that it will not be peeled off even during a typhoon.

Test method:
Weed control effect test Conducted on an average weed height of 25 cm (as of September 20, 2019) at the flowerbed (width 60 cm, length 15 m) attached to the Enry Okazaki Building, 3-5-3 Mutsuna, Okazaki City, Aichi Prefecture. In Examples 1 to 3, two sheets having a sheet width of 40 cm and a length of 15 m were arranged in parallel, and the sheet overlapping portion was set to 3 cm to cover the soil. The 10 cm portion on both sides of the seat can be completely shielded from light by bending the vertical portion of the inner surface of the flowerbed. In Comparative Examples 1 and 2, the overlapping portion of the sheets was set to zero.
Comparative Examples 3 and 4 are commercial products of other companies, and the same product shape as that of Example 1 was prepared, and the sheet ends were fixed with a string so that the sheet would not be blown by the wind. The string was stopped so that the force of crushing the grass by fixing did not work.

Sensory test score of grass growing condition after 2 weeks: Average height of grass is 3 cm or less, withered state (discolored to brown) is 80% or more, and grass is grown completely from the overlapping part of the sheet. Absent.
Score 2 points: The average height of the grass is 8 cm or less, the withered state is less than 50%, and some grass growth is observed from the overlapping part of the sheets.
Score 1 point: The average height of the grass is 10 cm or more, the withered state is less than 10%, and the growth of the grass is recognized from the sheet stacking part.

Sensory test of rainwater treatment function A test was conducted on September 22 at 16:00 in the rain.
Puddle condition on the weed control sheet Score 3 points: The rainwater pool on the sheet surface is less than 30 square centimeters. The pool is not in other parts.
Score 2 points: There are more than 30 square centimeters of rainwater pools on the surface of the sheet, and there are more than two places.
Score 1 point: There are multiple stormwater pools of 30 square centimeters or more on the sheet surface, and no drainage to the soil is performed.

Example 1
Mitsui Chemicals EPT4045 (100phr), Zinc Oxide No. 1 (10phr), Asahi # 60 (FEF) Carbon Black (150phr), Calcium bicarbonate (40phr), Mitsui Prime Polymer SP1020 (30phr), Paraffin Oil PW-90: Idemitsu Kosan Co., Ltd. (80 phr) was kneaded with a 110 L vanbury mixer for 20 minutes, and a non-crosslinked elastomer sheet was obtained with a 26-inch roll. The weight ratio of EPDM is 24%, the weight ratio of polyethylene resin resin is 7%, the weight ratio of carbon black is 37%, and the content of sulfur-based compound is 0%.
With a receiving roll, a sheet thickness of 2.6 mm and a width of 45 cm are cooled by a batch-off (Suzuka Engineering Co., Ltd.) machine, stacked on a 1 m x 1.4 m pallet while folding, and cut when the height reaches 90 cm. And put it in a metal BOX.

Example 2: The same procedure as in Example 1 was carried out except that the weight ratio of EPDM was changed to 21%, the weight ratio of polyethylene resin resin was changed to 9%, the weight ratio of carbon black was changed to 34%, and the sheet thickness was changed to 3.2 mm.

Example 3: The same procedure as in Example 1 was carried out except that the weight ratio of EPDM was changed to 18%, the weight ratio of carbon black was changed to 32%, and the sheet thickness was changed to 5.1 mm.

Comparative Example 1: The same procedure as in Example 1 was carried out except that the weight ratio of EPDM was changed to 31%, the weight ratio of polyethylene resin resin was changed to 6%, and the weight ratio of carbon black was changed to 28%.

Comparative Example 2: The same as in Example 1 except that the weight ratio of EPDM was changed to 33%, the weight ratio of polyethylene resin resin was changed to 0%, the weight ratio of carbon black was changed to 30%, and the content of sulfur-based compound was changed to 0.99%. went.

Comparative Example 3: Weed-proof sheet products of other companies: Weed-proof sheet manufactured by Dio Kasei Co., Ltd., Comparative example 4: Weed-proof sheet products of other companies: Saburn 240BB manufactured by DuPont

In Comparative Examples 4 and 5, there was no overlapping portion. In Examples 1 to 3, a dent having a width of 20 cm and a depth of 20 cm is dug in the ground every 5 m, and a weed-proof sheet of the present invention is laid in the dent along the shape of the dent, and then gravel until the dent is completely filled. Was laid out to serve as a drainage channel for rainwater at the weed control sheet construction site. Before laying gravel, a PVC pipe having a diameter of 30 mm was pierced into this portion in the direction of the ground so as to break through the weed-proof sheet of the present invention to prepare a drainage channel to the ground.
In the weed-proof sheet of the present invention, weed-proof sheet pins having a length of 20 cm were driven into the center positions of the overlapped portions at intervals of 60 cm to fasten the sheets.

It is best used in the facilities of "solar power plant" and "around the grave" where mowing management is frequently performed, which is a 20-year business in which the income from selling electricity decreases due to the shadow of sunlight due to the growth of grass. Is. In addition, it is effective to install it in a spot where you want to prevent weeds for a long period of time, such as a space on the side of a road that obstructs traffic or around a fence where the blade of a mower does not reach. Furthermore, construction on the flower beds and gardens of companies and the gardens of inns is also effective. Alternatively, as a management of mowing at a golf course, it is also effective to apply it to remote areas and mountains where mowing cannot be handled due to labor shortage.

Weed control is important because electric fences used for grazing or installed to prevent invasion of wild boars and other agricultural lands will not function if grass grows and touches the fence. Application to such a place is the optimum application method of the weed control sheet of the present invention.

1: Weed-proof sheet 2: Weed-proof sheet Product form width 3: Overlapping part when weed-proof sheet is installed 4: Indented part 5: Gravel 6: Resin pipe 7: Soil

Claims (2)

EPDM (Ethylene Propylene Diene Coweight Rubber) is 15 to 25% by weight of the elastomer composition, carbon black content is 30 to 45% by weight, and density is 890 to 920 kg / cubic meter of polyethylene resin resin is 7 to 10% by weight. % Of the uncrosslinked elastomer composition, the 2 mm test sheet has a tension strength of 2 MPa or more, a tensile elongation of 30% or more, a specific gravity of 1150 to 1350 kg / cubic meter, and a sheet thickness of 2.0 mm to 6. It is 6 mm, the sheet hardness is 60 to 80 in JISA hardness, the width is 39 cm to 91 cm, the total content of the sulfur-based cross-linking accelerator and sulfur is 0.001% by weight or less, and the aroma component in the oil component is 0. Uncrosslinked elastomer weed-proof sheet composition of 001% by weight or less and its weed-proof sheet product Lay it so that it overlaps 2 cm to 6 cm from the edge of the sheet, make concave diggings in the ground at least at intervals of 5 m, install the sheet according to the dents, and gravel so that the thickness is 5 cm or more from above. A sheet construction method for a weed-proof sheet according to claim 1, wherein the sheet is pressed with a dent, and at least one resin tube having a diameter of 3 cm or more is pierced into the recess, and rainwater or the like collected in the recess is discharged to the ground.

Images