JP2002281839A - Agricultural multi seat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agricultural mulch that can be used as a substitute for a conventional mulch film, is extremely safe, has sufficient durability during use, and rapidly biodegrades after use. Provide a sheet. SOLUTION: An agricultural multi-sheet containing 70 to 95 parts by weight of a natural polymer and 5 to 30 parts by weight of lignin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-sheet for agriculture, and more particularly to a multi-sheet for agriculture which maintains its strength during a plant growing period and can be extinguished in soil after use.

[0002]

2. Description of the Related Art Agricultural multi-sheets are materials for covering the ground around agricultural crops or flowers, and are used for the purpose of improving the quality and yield of agricultural crops or flowers by controlling the soil temperature and controlling the occurrence of weeds. Have been. Conventionally,
For this agricultural multi-sheet, a synthetic resin film such as polyethylene or polyvinyl chloride has been used. However, since these are hardly degraded by microorganisms in the soil, they need to be collected, landfilled and incinerated after use. The recovery, landfill, and incineration processes require special equipment, a great deal of labor and time, and are also problematic in terms of environmental pollution.

[0003] Therefore, for the purpose of reducing the burden on farmers and saving labor in farming, multi-sheets made of biodegradable plastic, which is naturally decomposed when used in soil after use, are becoming widespread. Here, biodegradable plastic means
"It can be used in the same way as ordinary plastic during use, and after use it becomes a low molecular compound due to the involvement of microorganisms or moisture in nature and eventually decomposes to water and carbon dioxide" In recent years, interest in biodegradable plastics has been extremely high due to increasing interest in environmental issues. Multi-sheets made from biodegradable plastics are required to have sufficient durability and the like as in conventional plastics. However, multi-sheets made from biodegradable resins such as polylactic acid, polycaprolactone, and polybutylene succinate are not only expensive compared to conventional polyethylene and polypropylene products, but also have a high biodegradation rate. There are drawbacks such as difficulty in adjusting the amount of biodegradation, and the fact that biodegradation does not proceed quickly.

Although the use of waste paper or recycled paper instead of the conventional multi-sheet has been studied, they are susceptible to water, and when exposed to night dew or rain, the strength is reduced and the shape is reduced. At present, collapse and the like are promoted, and they do not have durability enough to withstand practical use. JP 8-20
No. 5692 discloses a method for suppressing biodegradation by impregnating a paper base material with humic acid or humic acid salt.
Japanese Patent Publication No. 00 discloses a method of suppressing biodegradation by adding oxyquinoline or a derivative thereof, but there is a concern that it may adversely affect soil.

[0005]

In view of the above situation, the object of the present invention is to use as a substitute for a conventional multi-film, which is extremely safe and has sufficient durability during use. Another object of the present invention is to provide an agricultural multi-sheet that can be rapidly biodegraded after use.

[0006]

Means for Solving the Problems As a result of extensive studies, the present inventors have found that natural polymers are contained in the range of 70 to 95 parts by weight, and lignin in the range of 5 to 30 parts by weight. The present inventors have found that a sheet solves the above problems, and have completed the present invention.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The natural polymer used in the present invention is not particularly limited as long as it can be biodegraded in soil. Examples of the natural polymer include cellulose, cellulose derivatives, starch, starch derivatives, chitin and chitin derivatives. It is preferred to use.
As cellulose, wood pulp fiber produced by the sulfite method or the kraft method, biocellulose synthesized by microorganisms such as bacterial cellulose, cotton,
Cotton and the like. Examples of cellulose derivatives include acetyl cellulose, cellulose acetate, carboxymethyl cellulose, methyl cellulose, and hydroxyethyl cellulose. Examples of starch include corn starch, wheat, rice, potato, and sweet potato starch. Examples of the starch derivative include various modified starches such as oxidized starch, phosphorylated esterified starch, etherified starch, cold-water-soluble starch and enzyme-modified starch. Chitin derivatives include chitosan and the like. In addition, gum arabic, gum plant gums such as gum arabic, yam, konjac, plant mucilage such as trolley mallow, seaweeds such as alginic acid, funori, agar, vegetable proteins such as soy glue, gluten,
Animal proteins such as gelatin, glue, casein and the like can also be used.

The lignin used in the present invention is not particularly limited, and lignin sulfonic acid, kraft lignin,
And their modifications, Millwood Lignin (MW
L), blasted lignin, lignin extracted from wood with an organic solvent, and the like can also be used. To have practical water resistance, the organic sulfur content in lignin should be 4% by weight
Hereinafter, it is preferably 3% by weight. If the organic sulfur content exceeds 4% by weight, the hydrophilicity increases, and the organic sulfur is eluted from the sheet being used.

The agricultural multi-sheet of the present invention comprises 70 to 95 parts by weight of a natural polymer, preferably 70 to 85 parts by weight, and 5 to 30 parts by weight, preferably 15 to 35 parts by weight of lignin. It must be contained in an amount of 30 to 30 parts by weight. When it is desired to suppress biodegradation, the rate of biodegradation can be reduced by blending lignin having an organic sulfur content of 4% by weight or less with low hydrophilicity.

[0010] As a method for producing the agricultural multi-sheet of the present invention, when cellulose in the form of fiber such as pulp fiber is used as a natural polymer, a pulp slurry to which lignin has been added is used in a fourdrinier paper machine or a twin wire type. Paper machine,
The sheet may be manufactured by making a sheet using a circular net paper machine or the like.
In addition, various auxiliaries such as dispersants, thickeners, water retention agents, defoaming agents, and water resistance agents that are generally used for papermaking, and plasticizers, foaming agents, dyes, and pigments that are generally used. , Fertilizers and pesticides can also be added.

Alternatively, after preparing a sheet to which lignin is not added, a solution or dispersion of lignin may be coated or impregnated on both sides or one side of the sheet. Examples of the coating apparatus include coating apparatuses such as a blade coater, an air knife coater, a roll coater, a bar coater, a curtain coater, and a spray coater which are used in general coated paper production. Single or multi-layer coating is applied on the sheet.

When a natural polymer which is not in a fiber form is used, the natural polymer and lignin may be kneaded and then processed into a molded article. It is manufactured by a general kneading device or molding device. As a kneading device, a roll mill, an intensible mixer, a short screw extruder, a twin screw extruder, or the like can be used.
In addition, a T-shaped die and an inflation die can be used as a molding device.

The sheet thus manufactured is cooled and commercialized as it is, or is subjected to surface oxidation such as corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet irradiation, sand blast treatment or solvent treatment. Unevenness of surface, bonding by solvent, adhesive or heat, lamination processing such as extrusion method, hot melt method, dry method, wet method, gravure roll, Meyer bar, doctor blade, reverse roll coater, air knife coater, etc. Secondary processing such as coating processing, vacuum deposition processing, and antistatic processing is performed as necessary.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, parts and% indicate parts by weight and% by weight, respectively, unless otherwise specified. The sheets manufactured in Examples and Comparative Examples were evaluated for durability and biodegradability by the following methods.

<Evaluation of Biodegradability> Evaluation of biodegradability in soil was carried out in a greenhouse at 25 ° C. by using nursery soil in Tsuchiura Greening Center of NP General Development Co., Ltd. as soil. 5c
Cut into a strip of mx 15cm and place the sample in the ground with 2c above ground
m, and was collected one month later, and the state of decomposition was evaluated separately for ground and soil. As for the decomposition at the ground, the length remaining without being cut by the decomposition at the ground was measured and expressed as% of the total width of the sample. Decomposition in the soil was visually evaluated.

Example 1 Starch-based biodegradable plastic (trade name: CPR-F3E, Nippon Cornstarch Co., Ltd.)
A mixture consisting of 90 parts by weight and 10 parts by weight of ligninsulfonic acid (trade name: Vanilex HW, manufactured by Nippon Paper Industries Co., Ltd.) having an organic sulfur content of 2.4% by weight was kneaded at 130 ° C. with an intensible mixer. And a T-type die to obtain a multi-sheet having a thickness of 30 μm. The biodegradability of the obtained multi-sheet was evaluated, and the results are shown in Table 1.

Example 2 Kraft lignin was added to kraft pulp slurry, and a handmade paper having a basis weight of 70 g / m ² and a lignin content of 10% by weight was prepared using a Tappi standard sheet machine. The biodegradability of this handmade paper was evaluated, and the results are shown in Table 1.

Example 3 45 parts by weight of chitosan (trade name: Noskin MA-1, manufactured by Hokkaido Soda Co., Ltd.), cellulose powder (trade name: KC-400, manufactured by Nippon Paper Industries Co., Ltd.)
Lignin sulfonic acid having an organic sulfur content of 45% by weight (trade name: Vanirex HW, Nippon Paper Industries Co., Ltd.)
The mixture consisting of 10 parts by weight was kneaded with an intensible mixer at a temperature of 130 ° C., and then extruded with a T-type die to a thickness of 5%.
A 0 μm multi-sheet was obtained. The biodegradability of the obtained multi-sheet was evaluated, and the results are shown in Table 1.

Comparative Example 1 A multi-sheet was prepared and evaluated for biodegradability in the same manner as in Example 1 except that ligninsulfonic acid was not added. The results are shown in Table 1.

Comparative Example 2 A hand-made paper multi-sheet was prepared in the same manner as in Example 2 except that no kraft lignin was added, and the biodegradability was evaluated. The results are shown in Table 1. .

Comparative Example 3 A multi-sheet was prepared and biodegradability was evaluated in the same manner as in Example 3 except that ligninsulfonic acid was not blended. The results are shown in Table 1. .

[0022]

[Table 1] The agricultural multi-sheet containing lignin of Examples 1 to 3 was excellent in durability. On the other hand, the agricultural multi-sheets of Comparative Examples 1 to 3 which did not contain lignin were inferior in durability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 5/08 C08L 5/08 97/00 97/00 D21H 17/21 D21H 17/21 17/23 17 / 23 27/00 27/00 Z (72) Inventor Nobuhiro Hato 5-21-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. F-term (reference) 2B024 DB03 DB10 DC10 4F071 AA09 AA70 AA73 AH01 BA01 BA07 BB02 BB06 BB09 BC01 4J002 AB011 AB021 AB031 AB041 AB051 AD011 AD021 AD031 AH002 GA01 4L055 AC06 AG44 AG46 AG48 AG99 EA32 FA20 GA25

Claims (2)

[Claims] 1. An agricultural multi-sheet comprising 70 to 95 parts by weight of a natural polymer and 5 to 30 parts by weight of lignin. 2. The agricultural multi-sheet according to claim 1, wherein the natural polymer is at least one selected from cellulose, cellulose derivatives, starch, starch derivatives, chitin, and chitin derivatives.