JP2004180522A - Weed-proofing film or sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weed-proofing film or sheet having excellent shading properties, high weed-proofing effects, excellent biodegradability and excellent mechanical strength. <P>SOLUTION: The weed-proofing film or sheet comprises an aliphatic or an alicyclic polyester resin containing a constituent unit derived from an aliphatic or an alicyclic diol and a constituent unit derived from an aliphatic or an alicyclic dicarboxylic acid and having 10,000-200,000 number-average molecular weight and a polyester resin composition containing wood flour. The film or sheet has ≥90% shading ratio. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a herbicidal film or sheet, and more specifically, to a herbicidal film or sheet having excellent light-shielding properties, high herbicidal effect, excellent biodegradability, and excellent mechanical strength. About.
[0002]
[Prior art]
Conventionally, for example, as a weeding method in places where weeds tend to thrive, such as shoulders of roads, median strips, traffic islands, cut and embankment slopes, and parks, green areas, and other planting areas Is a method for suppressing the growth of weeds by covering the surface with a herbicide such as a resin film or a sheet or a nonwoven fabric sheet and shielding the light against temporary methods such as manual weeding and spraying of a herbicide. However, when they are broken with the passage of time, if they are left as they are, they will remain in their original form, leading to various problems, or it will take labor to collect and dispose of them. In addition, there is a problem that the environment is polluted.
[0003]
On the other hand, a herbicidal sheet (for example, see Patent Document 1) made of a nonwoven fabric of a resin fiber obtained by adding a pigment to a biodegradable aliphatic polyester resin to impart light-shielding properties, and a biodegradability. Weed deterrent boards or sheets made of a resin having a light-shielding property obtained by mixing shreds of natural wastes such as weeds and crushed wood powder into an aliphatic polyester resin or the like (for example, see Patent Document 2). A method for imparting biodegradability to a herbicide has been proposed.
[0004]
[Patent Document 1]
JP-A-11-229260.
[Patent Document 2]
JP-A-2001-346454.
[0005]
However, according to studies by the present inventors, all of the biodegradable herbicides disclosed in these patent documents leave room for further improvement in terms of biodegradability and mechanical strength. Was also inferior.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described prior art, and has excellent light-shielding properties, a high herbicidal effect, a high biodegradability, and a mechanical protection film or sheet having excellent mechanical strength. The purpose is to provide.
[0007]
[Means for Solving the Problems]
The present inventors are aliphatic polyesters having excellent biodegradability as a biodegradable resin, and while selecting a high molecular weight product thereof, by incorporating wood powder for imparting light-shielding properties, It has been found that the object can be achieved and the present invention has been reached.Therefore, the present invention includes a structural unit derived from an aliphatic or alicyclic dicarboxylic acid and a structural unit derived from an aliphatic or alicyclic dicarboxylic acid, A herbicidal film or sheet comprising a polyester resin composition containing an aliphatic or alicyclic polyester resin having an average molecular weight of 10,000 to 200,000 and wood flour, and having a light blocking ratio of 90% or more. Make a summary.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The herbicidal film or sheet of the present invention comprises an aliphatic or alicyclic polyester resin containing a structural unit derived from an aliphatic or alicyclic diol and an aliphatic or alicyclic polyester resin containing a structural unit derived from an aliphatic or alicyclic dicarboxylic acid. And a polyester resin composition containing powder.
[0009]
Here, the aliphatic or alicyclic polyester resin is a polycondensate or copolycondensate of an aliphatic or alicyclic diol and an aliphatic or alicyclic dicarboxylic acid, and the aliphatic or alicyclic diol is Is preferably an aliphatic diol having 2 to 10 carbon atoms or an alicyclic diol having 3 to 10 carbon atoms, and the aliphatic or alicyclic dicarboxylic acid preferably has 2 carbon atoms other than the carboxyl group. Preferred are aliphatic dicarboxylic acids having up to 12 or alicyclic dicarboxylic acids having 3 to 12 carbon atoms other than a carboxyl group.
[0010]
Specific examples of the aliphatic or alicyclic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, , 8-octanediol, 1,10-decanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethylol, 1,4-cyclohexanedimethylol, and the like. 1,4-butanediol is particularly preferred. Specific examples of the aliphatic or alicyclic dicarboxylic acid include, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, hexahydrophthalic acid Examples thereof include acids, hexahydroisophthalic acid, hexahydroterephthalic acid, and derivatives of these dicarboxylic acids such as alkyl esters having about 1 to 4 carbon atoms and anhydrides. Among them, succinic acid is particularly preferred.
[0011]
The aliphatic or alicyclic polyester resin in the present invention must have a number average molecular weight of 10,000 to 200,000, and preferably 20,000 to 150,000. If the number average molecular weight is less than the above range, the mechanical strength as a film or sheet of the resin composition containing wood flour will be inferior, whereas, if the number average molecular weight exceeds the above range, molding processability into a film or sheet will be inferior, In addition, the biodegradability also decreases.
[0012]
In order that the aliphatic or alicyclic polyester resin in the present invention satisfies the range of the number average molecular weight, the polyester resin may be a structural unit derived from the aliphatic or alicyclic diol and the aliphatic or alicyclic diol. In addition to the structural unit derived from the formula dicarboxylic acid, the molecular weight is increased by including a structural unit derived from an aliphatic or alicyclic oxycarboxylic acid, or the terminal is substantially a hydroxyl group. It is preferable to employ a method in which an isocyanate compound as a coupling agent is added to the polyester diol in a molten state to increase the molecular weight by a urethane bond.
[0013]
Among these methods for increasing the molecular weight, the latter method may cause coloring or the like depending on the conditions for forming the film or sheet, and the former method is preferred because the biodegradability is slightly inferior. preferable.
[0014]
As the aliphatic or alicyclic oxycarboxylic acid in the present invention, a 2-hydroxyalkanoic acid having 2 to 12 carbon atoms is preferable, and specifically, for example, glycolic acid, lactic acid, 2-hydroxy-n-butyric acid , 2-hydroxy-3-methyl-n-butyric acid, 2-hydroxy-3,2-hydroxy-n-valeric acid, 2-hydroxy-n-hexanoic acid, 2-hydroxy-i-hexanoic acid, and the like, Among them, glycolic acid or lactic acid is particularly preferred.
[0015]
Further, as the aliphatic or alicyclic polyester resin in the present invention, from the viewpoints of moldability into a film or a sheet, mechanical strength as a film or a sheet, and biodegradability, the aliphatic or alicyclic resin may be used. Structural units derived from diols are 35-49.99 mol%, constitutional units derived from aliphatic or alicyclic dicarboxylic acids are 35-49.99 mol%, and aliphatic or alicyclic oxycarboxylic acids are derived. It is preferable that the structural unit is composed of 0.02 to 30 mol%, and the structural unit derived from an aliphatic or alicyclic diol is 40 to 49.75 mol%, and the structural unit is derived from an aliphatic or alicyclic dicarboxylic acid. Is more preferably 40 to 49.75 mol%, and 0.5 to 20 mol% of a constituent unit derived from an aliphatic or alicyclic oxycarboxylic acid. Is 45 to 49.5 mol% of a structural unit derived from an alicyclic diol, 45 to 49.5 mol% of a structural unit derived from an aliphatic or alicyclic dicarboxylic acid, and is an aliphatic or alicyclic oxycarboxylic acid. Those having a constitutional unit derived from an acid of 1 to 10 mol% are particularly preferred.
[0016]
In addition, the aliphatic or alicyclic polyester resin in the present invention may further include, for example, aromatic diols such as 2,2-bis (4′-hydroxyphenyl) propane, terephthalic acid, and isophthalic acid as copolymer components. Aromatic dicarboxylic acids, and aromatic oxycarboxylic acids such as hydroxybenzoic acid, and trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, gallic acid, and apple acid, tricarballylic acid, trimellitic acid, trimesin A trifunctional or higher polyfunctional component such as an acid or pyromellitic acid may be contained as a constituent unit in an amount of 5 mol% or less based on all components.
[0017]
Moreover, in the film or sheet for weed control of the present invention, the polyester resin composition essentially contains the above-mentioned aliphatic or alicyclic polyester resin and wood powder for imparting light-shielding properties. Here, when wood powder is not contained, the biodegradability as a grass-protecting film or sheet is inferior even though light-shielding properties can be imparted. In order to improve the light-shielding property, a filler other than wood flour, such as carbon black, may be used in combination as long as the biodegradability is not impaired.
[0018]
Although the material of the wood flour is not particularly limited, the average particle diameter is 1 mm or less from the viewpoint of moldability to a film or sheet as a resin composition, and mechanical strength as a film or sheet. Is preferable, and it is particularly preferable that it is 0.5 mm or less.
[0019]
In the present invention, as the polyester resin composition containing the aliphatic or alicyclic polyester resin and the wood flour, the content ratio of the wood flour is 40 to 200 parts by weight based on 100 parts by weight of the polyester resin. , And particularly preferably 60 to 150 parts by weight. If the content of the wood powder is less than the above range, the light-shielding properties as a film or sheet for weeds tends to be inferior, whereas, if the content is more than the above range, the molding processability into a film or sheet as a resin composition, and the film or The mechanical strength of the sheet tends to be poor.
[0020]
In the present invention, the polyester resin composition containing the aliphatic or alicyclic polyester resin and the wood flour further includes an antioxidant, an ultraviolet absorber, a light stabilizer, and a stabilizer, which are generally used for a resin molded product. It may contain an antistatic agent, a lubricant, an antiblocking agent, a release agent, an antifogging agent, a nucleating agent, a plasticizer, a coloring agent, and the like.
[0021]
The film or sheet for weed control of the present invention may be a conventionally known film or sheet formed by extrusion molding of the polyester resin composition from an extruder equipped with a T die or an annular die, or calendering by a calender roll. It is formed by the method.
[0022]
The thickness of the herbicidal film or sheet of the present invention also depends on the content of the wood flour in terms of light-shielding properties. Alternatively, it is determined in consideration of the flexibility of the sheet, but is preferably about 0.2 to 2 mm, and particularly preferably about 0.5 to 1.5 mm.
[0023]
The film or sheet for weed control of the present invention has a light shielding ratio of 90% or more, obtained from the illuminance (B) when the light source is transmitted through the film or sheet and the illuminance (A) of the blank, when the light shielding ratio is 90% or more. It is essential that it is present, it is preferably at least 95%, particularly preferably 100%.
Shading ratio (%) = [(AB) × 100] / A
[0024]
In addition, the film or sheet for weed control of the present invention, when there is a plant on the covering surface of the place of use, for the purpose of supplying water to the plant, a large number of through holes are formed in the film or sheet. May be done.
[0025]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.
[0026]
Example 1
Consisting of 47.8 mol% of a constitutional unit derived from 1,4-butanediol, 47.8 mol% of a constitutional unit derived from succinic acid, and 4.4 mol% of a constitutional unit derived from lactic acid, and has a number average molecular weight of 69. By adding 80 parts by weight of wood powder having an average particle size of about 0.3 mm to 100 parts by weight of 2,000 aliphatic polyester resin, melt extruding into a sheet at 180 ° C. by an extruder equipped with a T-die, and cooling. And a sheet for weed control having a width of 1 m, a length of 100 m and a thickness of 0.5 mm. The light shielding ratio of the obtained sheet was 100%, and the tensile strength at break was 30 MPa.
[0027]
When a test for accelerating biodegradability was carried out on this sheet by the method described below, the sheet test piece was biodegraded, and almost no residual was observed.
<Biodegradability acceleration test>
A test piece cut out from the sheet into a size of 2 cm × 2 cm was provided with 5 units / ml of lipase (Rhizopus delemer, manufactured by SIGMA) and 0.005% by weight of a surfactant (“Plysurf A210G” manufactured by Daiichi Kogyo Seiyaku). Immersed in a phosphate buffer solution containing water, allowed to stand for 24 hours, and then buried at a depth of 10 cm in the soil of a test field at Yokohama Science and Technology Research Center, Mitsubishi Chemical Corporation. It was confirmed.
[0028]
Example 2
Consisting of 48.8 mol% of a structural unit derived from 1,4-butanediol, 48.8 mol% of a structural unit derived from succinic acid, and 2.4 mol% of a structural unit derived from glycolic acid, and has a number average molecular weight. A herbicidal sheet was produced in the same manner as in Example 1 except that 42,500 aliphatic polyester resins were used. The light shielding ratio of the obtained sheet was 100%, and the tensile strength at break was 25 MPa. Further, in the test for accelerating biodegradability, the sheet test piece was biodegraded, and its residual was hardly confirmed.
[0029]
Example 3
A herbicidal sheet was produced in the same manner as in Example 1 except that a commercially available aliphatic polyester resin (number average molecular weight: 26,000, manufactured by Showa Polymer Co., Ltd., "Bionole") having a high molecular weight by a urethane bond was used. . The obtained sheet had a light blocking ratio of 100% and a tensile strength at break of 20 MPa. In addition, slight yellow coloring was recognized on the sheet. In the test for accelerating biodegradability, the sheet test piece was almost biodegraded, but a partial remaining was confirmed.
[0030]
Comparative Example 1
A herbicidal sheet was produced in the same manner as in Example 1 except that a commercially available polylactic acid resin ("Nature Works" manufactured by Cargill Dow Japan KK) was used. The light shielding ratio of the obtained sheet was 100%, and the tensile strength at break was 10 MPa. In the test for promoting biodegradability, the presence of the sheet test piece was confirmed although it was slightly infested.
[0031]
Comparative Example 2
A herbicidal sheet was produced in the same manner as in Example 3 except that 20 parts by weight of carbon black was used instead of wood flour. The light shielding ratio of the obtained sheet was 100%, and the tensile strength at break was 25 MPa. In the test for promoting biodegradability, the presence of the sheet test piece was confirmed although it was slightly infested.
[0032]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, while having excellent light-shielding properties, high herbicidal effect, excellent biodegradability, and excellent mechanical strength, it is possible to provide a herbicidal film or sheet.

Claims (6)

An aliphatic or alicyclic polyester resin containing a structural unit derived from an aliphatic or alicyclic diol and a structural unit derived from an aliphatic or alicyclic dicarboxylic acid, and having a number average molecular weight of 10,000 to 200,000; A film or sheet for herbicidal use, comprising a polyester resin composition containing, and a wood flour, and having a light blocking ratio of 90% or more. The herbicidal film or sheet according to claim 1, wherein the aliphatic or alicyclic diol is 1,4-butanediol, and the aliphatic or alicyclic dicarboxylic acid is succinic acid. The herbicidal film or sheet according to claim 1 or 2, wherein the aliphatic or alicyclic polyester resin further contains a constituent unit derived from an aliphatic or alicyclic oxycarboxylic acid. The weed control film or sheet according to claim 3, wherein the aliphatic or alicyclic oxycarboxylic acid is glycolic acid or lactic acid. The aliphatic or alicyclic polyester resin is composed of 35 to 49.99 mol% of a structural unit derived from an aliphatic or alicyclic diol, and 35 to 49.99 mol% of a structural unit derived from an aliphatic or alicyclic dicarboxylic acid. 5. The herbicidal film or sheet according to claim 3, which comprises 0.02 to 30 mol% of a structural unit derived from an aliphatic or alicyclic oxycarboxylic acid. 6. The weed control film or sheet according to any one of claims 1 to 5, wherein the wood flour has an average particle diameter of 1 mm or less.