JPH0443009Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an agricultural soil covering sheet, and more particularly to a reinforced sheet-like breathable polyurethane foam for covering soil, such as in citrus orchards, or after sowing.

Background of the invention Citrus cultivation in Japan is generally carried out under conditions where the cultivated soil is shallow and organic matter in the soil is easily depleted. 87% of the cultivation area is on sloped land, with most of the cultivation occurring on steep slopes of 15 degrees or more. The area it occupies is really
It is said that the percentage is as high as 46%. Under these conditions, the issue of soil conservation to protect soil from erosion is an important issue in citrus orchard soil management. At the same time, it also leads to larger issues that go beyond fruit tree cultivation, such as disaster prevention and national land conservation.

Among the factors related to soil erosion, the amount and intensity of rainfall are important external factors, but the amount of rainfall per unit time, that is, the intensity of rainfall, is more important than the absolute amount of rainfall. Also, factors from the soil side include the presence or absence of cover, topography, soil texture, etc. If the soil is covered with grass, bedding, straw, etc., the initial trigger of soil erosion, which is the dispersion of soil particles by raindrops, will be eliminated, and the soil structure will be improved through agglomeration and water infiltration. This has the effect of increasing the amount of runoff, reducing the amount of runoff that causes soil erosion, or slowing down the runoff rate. Therefore, covering soil acts on all factors related to soil erosion and is the basis of soil conservation.

As mentioned above, soil covering methods include weeds and grasses, bedding with grass and other organic matter (buckwheat hulls, sawdust, bark scraps, etc.), and bedding with rice straw. Among them, the straw bedding method minimizes the amount of runoff water and washed away soil, which are the causes of soil erosion, and maximizes the amount of water that permeates.

Therefore, rice straw, an agricultural by-product, has been widely used as bedding for citrus orchards. However, it is becoming increasingly difficult to obtain these organic resources over the years in places where the cultivation areas have advanced urbanization and industrialization along the coastline, such as the Seto Inland Sea coast, or in places where rice cultivation and livestock farming are not popular, such as on the island's shores. It has become increasingly strong.

Traditionally, agricultural covering materials used in contact with the ground surface include ``Agricultural protection pine'' published in Utility Model Publication No. 155957/1983 and ``Artificial soil for growing seedlings with improved water absorption'' in Japanese Patent Publication No. 1983-106232. ``Urea resin foam pine for gardening'' and Japanese Patent Publication No. 1983-63113 ``Artificial sphagnum moss for gardening''. However, all of these materials are mainly used to protect crops on the ground, such as for strawberry cultivation and seedling raising, and from the viewpoint of the material of the pine, polyolefin, polystyrene, melamine/urea, etc. are used for open-cell foam. Unsuitable for continuous production of foam. Furthermore, even when urethane foam is used, such as in a water basin, the foam only has enough strength to withstand use inside a flowerpot. Thus, an agricultural soil covering sheet designed as a substitute for citrus orchard litter, for example, has not been known so far.

Details of the invention The present invention aims to provide, in place of these natural products, a covering material for agricultural soil management that is inexpensive, has a stable supply, and has excellent performance as bedding material. Therefore, the present invention is an agricultural soil covering sheet having a structure that combines a sheet-like breathable polyurethane foam and a reinforcing material, and in this case,
The reinforcing material uses a water-insoluble base material and a water-insoluble superabsorbent hydrogel in combination, and has the following characteristics.

(b) By selecting an appropriate size and shape, it can be used for fruit cultivation and other agricultural purposes depending on the situation and topography.

(b) Since the size of the foam cells can be arbitrarily selected during production, air permeability and water absorption and water retention properties can be adjusted.

(c) If this sheet is left unattended after application, the polyurethane foam will eventually decompose and become a nitrogen fertilizer component. Furthermore, if a natural or synthetic organic material is selected for the reinforcing material, it will decompose in the same way and become a fertilizer component depending on the material. Therefore, the sheet does not have to be collected after application.

(d) Properties such as water retention and water permeability can be increased or adjusted by selecting the material and structure of the reinforcing material, and various usage forms can be considered in terms of properties and ease of handling. It will be done.

(e) By impregnating the obtained pine with inorganic salts such as phosphoric acid and potassium, these ingredients permeate into the ground in response to rainfall, contributing to the adjustment of the balance of effective fertilizer ingredients.

The soil covering sheet of the present invention may be made of a known sheet made of breathable flexible polyurethane foam or a sheet made of independent cell polyurethane foam in which independent cells are made to communicate with each other by machining. These polyurethane foams are
It can be easily produced by a conventional foaming technique from a general-purpose polyisocyanate such as TDI or MDI and an ether type or ester type polyol containing a reactive hydroxyl group.

As the reinforcing material for the sheet of the present invention, natural materials such as paper, cotton, fibers, and wood, synthetic fibers, woven fabrics, nonwoven fabrics, nets, threads, etc. made from these materials, or combinations thereof can be used. For example, if a string-like material in which fibers are arranged in the same direction is used as a type of nonwoven fabric, the sheet material can be easily torn by hand to the desired width for use.
Also, depending on the combination of the foam sheet and each reinforcing material, extremely diverse usage forms can be considered in terms of properties such as water retention and water permeability, and ease of handling.

As a reinforcing material, in addition to the water-insoluble base materials mentioned above, saponified products of starch-acrylonitrile graft polymers, saponified polyacrylonitrile products, saponified products of vinyl ester-ethylenically unsaturated carboxylic acid copolymers, polyethylene oxide, polyvinyl alcohol, polyvinyl The water retention of the sheet can be improved by appropriately using water-insoluble super absorbent hydrogels such as crosslinked products such as pyrrolidone, sodium polyacrylate, polyacrylamide, sodium polyacrylate-polyacrylamide copolymer, carboxymethyl cellulose, dextrin, and pullulan. Increase can be adjusted. These reinforcing materials can be attached to one or both sides of the finished polyurethane sheet, or between sheets, by using an adhesive or by fusing the sheet surfaces together, or by interposing these reinforcing materials during foam foaming. It is also possible to combine the two to form a sheet.
Also, by applying striations to the foam sheet, water retention and applicability can be improved. Furthermore, there are various embodiments depending on the combination of these processing methods and reinforcing materials.

Next, the present invention will be exemplarily explained with reference to the drawings.

FIG. 1 is a perspective view of a sheet material in which a woven fabric 2 (consisting of warp yarns 2' and weft yarns 2'') is adhered to one side of a sheet 1 of breathable polyurethane foam.

FIG. 2 is a bottom view of the sheet material of FIG. 1, that is, a plan view seen from the woven fabric side.

FIG. 3 is a perspective view of a sheet material in which a string-shaped nonwoven fabric 4 is adhered to one side of a sheet 3 of breathable polyurethane foam that has been subjected to directional striations.

FIG. 4 is a bottom view of the sheet material of FIG. 3, that is, a plan view seen from the nonwoven fabric side.

FIG. 5 is a perspective view of a sheet material in which long fibers 6 are non-directionally dispersed in a sheet 5 of breathable polyurethane foam during foaming.

[Brief explanation of the drawing]

1 and 3 are perspective views of the sheet material of the present invention, and FIGS. 2 and 4 are bottom views thereof. FIG. 5 is a perspective view of a sheet material according to another embodiment of the present invention. In the drawings: 1... form sheet, 2...
Woven fabric, 3...foam sheet with striations,
4...String type nonwoven fabric, 5...Foam sheet, 6...Long fiber.

Claims (1)

[Scope of utility model registration request] An agricultural soil covering sheet consisting of a sheet-like breathable polyurethane foam combined with a reinforcing material, where the reinforcing material is a combination of a water-insoluble base material and a water-insoluble superabsorbent hydrogel. The sheet characterized by: