JP3118352B2 - Water-soluble film for agricultural chemical packaging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates has excellent performance as a unit packaging agricultural chemicals, to agricultural chemicals packaging water soluble film and pesticide packaging.

[0002]

2. Description of the Related Art In recent years, various chemicals such as agricultural chemicals are hermetically packaged (unit wrapped) in a unit amount in a water-soluble film, and then put into water in the form of the package when used.
A method of dissolving or dispersing the contents together with the packaging film in water has been used. The advantages of this unit package are that it can be used without directly touching dangerous chemicals at the time of use, and that weighing is not required at the time of use because a fixed amount is packed. Conventionally, an unmodified partially saponified polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) film has been used as such a water-soluble film for unit packaging. These water-soluble films are easily soluble in cold water and have excellent mechanical strength and good performance, but they have many active agents and dispersants with functional groups contained as pesticides and their auxiliaries. And the carrier and the like gradually react with the PVA-based film as the package, and the water-soluble property of the PVA-based film decreases with time,
During long-term storage, it becomes insoluble or hardly soluble in water, making it unusable. At present, it cannot be widely used due to these problems. As one of such measures, use of a carboxylic acid-modified PVA film has been attempted in order to suppress a decrease in water solubility. However, the film has the property that the heat resistance is insufficient or the water solubility is reduced upon standing, and when PVA itself is packaged, furthermore, when a pesticide is packaged, ionic crosslinking with the polyvalent metal salt contained in the pesticide or There is a problem in that the water solubility is lowered by chelate crosslinking, or the water reacts with the functional group contained in the pesticide, and the water solubility is lowered with time. In addition to carboxylic acid modification, attempts have been made to introduce an oxyalkylene group or a cationic group into PVA. However, when these modifications are performed, high molecular weight PVA cannot be obtained and the film strength is extremely high. It has disadvantages such as lowering, becoming hard and brittle in winter when humidity dependency is large and humidity is low, and it becomes a completely rigid film on rainy days. There is a problem in that it reacts with a group to cause a decrease in water solubility.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a film for packaging pesticides which does not have the above-mentioned drawbacks, has excellent mechanical strength, has a film property which is flexible and tough, and is used for a long time. An object of the present invention is to provide a water-soluble film for agrochemical packaging, which maintains good water solubility even when packaged.

[0004]

Means for Solving the Problems In view of the present situation, the present inventors have conducted intensive studies, and as a result, contained 0.5 to 10 mol% of a sulfonic acid group unit represented by the following chemical formula 2, and obtained a viscosity average weight.
Total degree 500-4000, saponification degree 70-99.5 mol%
100 parts by weight of modified polyvinyl alcohol
Film containing 5 to 30 parts by weight of alcohol plasticizer
Complete dissolution time of less than 30 seconds after packaging
From a water-soluble film for packaging agricultural chemicals and the film
The present inventors have found a pesticide package in which a pesticide is packaged in a bag to complete the present invention. Here, complete dissolution after packaging of the pesticide
The solution time is, as described in Examples described later, the present invention.
Agricultural chemicals are wrapped in bags obtained from the film of
After leaving for 4 weeks, the film in the bag is
Cut into squares, scissor this on a slide mount, 10 ° C
Immersed in the stirring water to completely dissolve the film.
Means the time it takes to

[0005]

Embedded image

(Where R ¹ is a hydrogen atom or a lower alkyl group, R ² is an alkyl group, R ³ , R ⁴ and R ⁵ are a hydrogen atom or an alkyl group, M is a hydrogen atom, an alkali metal, an ammonium group or an amine. The modified PVA containing a sulfonic acid group unit represented by the above general formula is
It does not react with polyvalent metal salts or compounds having various functional groups contained in pesticides, their auxiliaries and their carriers, and is chemically very stable. Almost no decrease in water solubility over time. Further, the sulfonic acid group contained in the modified PVA of the present invention has a strong hydrophilic group, and therefore has a significantly higher dissolution rate in water than the unmodified PVA film.

Hereinafter, the present invention will be described in more detail. The modified PVA used in the present invention is a modified polyvinyl alcohol containing a sulfonic acid group unit represented by the above general formula in an amount of 0.5 to 10 mol%. The modified PVA is obtained by copolymerizing a vinyl ester and a polymerizable monomer containing a sulfonic acid group represented by the following formula 3 in the presence of a radical initiator in a bulk or in a solution using a solvent such as an alcohol. The resulting copolymer is partially or highly saponified by the action of an alkali or acid catalyst.

[0008]

Embedded image

(Where R ¹ , R ² , R ³ , R ⁴ and R ⁵
Has the same meaning as in Chemical Formula 2. Here, the vinyl ester includes vinyl acetate, vinyl propionate, vinyl formate, vinyl versatate, vinyl pivalate and the like, and vinyl acetate which is industrially produced and has a cost advantage is usually used. Polymerizable monomers containing a sulfonic acid group of the present invention is represented by the above chemical formula 3, R ¹
Is a hydrogen atom or a lower alkyl group, and is preferably a hydrogen atom or a methyl group. It is essential that R ² is an alkyl group, preferably an alkyl group having 1 to 3 carbon atoms, because of increasing the chemical stability of the amide group,
This is to prevent the bond from being broken by hydrolysis even in the saponification reaction. R ³ , R ⁴ and R ⁵ are a hydrogen atom or an alkyl group. Among them, R ³ is preferably an alkyl group, and more preferably an alkyl group having 1 to 3 carbon atoms, from the viewpoint of the stability of the amide group. R ⁴ and R ⁵
Is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. M is a hydrogen atom, an alkali metal, an ammonium group or an amine group;
a, K, and Li. When M is a hydrogen atom, the sulfonic acid group is a strong acid, which may cause a problem such as hydrolysis of the vinyl ester during the copolymerization. Desirably, it is neutralized with a metal.

Specific examples of typical sulfonic acid group-containing monomers for the purpose of the present invention include the following. 2-acrylamide-2-methylpropanesulfonic acid or an alkali metal salt thereof, 2-acrylamide-1
-Methylpropanesulfonic acid or an alkali metal salt thereof, and 2-methacrylamide-2-methylpropanesulfonic acid or an alkali metal salt thereof. Among them, 2-acrylamido-2-methylpropanesulfonic acid or an alkali metal salt thereof is preferable from the viewpoint of copolymerization reactivity with a vinyl ester and stability during saponification. The copolymer obtained by copolymerization is usually saponified in an alcohol solution using an alkali or acid catalyst to produce a modified PVA containing a sulfonic acid group used in the present invention. The content of the sulfonic acid group unit in the sulfonic acid group-containing modified PVA is 0.5 to 10 mol%, more preferably 1 to 5 mol%. If the content is less than the lower limit, the stability over time of the water solubility when the pesticide is packaged is poor, and the dissolution rate in water is undesirably low. When the content is larger than the upper limit , the strength of the film is greatly reduced, and the film becomes hard and brittle, and cannot be used due to the problem of physical properties as a film.

The degree of polymerization of the modified PVA is not particularly limited, but the mechanical properties of the film are also important.
Since strong strength and flexibility are required even at a thin thickness of μm, the viscosity average polymerization degree is more preferably 500 to 4000 from the viewpoint of film strength and toughness. Degree of polymerization
If it is less than the lower limit , the film strength tends to be weak, and if the polymerization degree is more than the upper limit , the solution viscosity at the time of preparing the film becomes high, and there is a problem in workability, which is not preferable. The degree of saponification of the modified PVA is preferably 7 in consideration of film strength, film stiffness and bag-making properties.
0 to 99.5 mol%.

Regarding the method for producing the modified PVA of the present invention,
Although described in detail above, the following modified PVA cannot be used because it is not preferred in the present invention. Conventionally known methods of introducing a sulfonic acid group into PVA include a method of reacting PVA with concentrated sulfuric acid, a method of oxidizing with iodine or the like and then reacting with acidic sodium sulfite, or an aldehyde having a sulfonic acid group. Modification by the so-called post-reaction such as the method of acetalization using can be synthesized in the laboratory, but the process is complicated and costly expensive industrially, and uniform denaturation is not possible in terms of performance, There are many problems such as the inability to produce a modified PVA having a high degree of polymerization. Further, modified PVA obtained by saponifying a copolymer of olefin sulfonic acid such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid or a salt thereof with a vinyl ester,
The low solubility of the olefin sulfonic acid in the vinyl ester or solvent during the production makes it difficult to produce under favorable conditions, and the polymerization rate is low, and the degree of polymerization of the obtained copolymer is low. The film has a fatal defect that an excellent film cannot be obtained and cannot be used. As another sulfonic acid group-containing monomer, sulfoalkyl (meth)
A sulfonic acid-modified polyvinyl ester obtained by copolymerization of a vinyl ester with a monomer having a sulfonic acid in an ester group of an acrylic acid ester or another copolymerizable acid can be synthesized, but it can be synthesized by a subsequent saponification reaction. The ester group in the sulfonic acid group-containing unit is similarly saponified,
The resulting modified PVA cannot be used because it cannot contain a sulfonic acid group.

The film for packaging agrochemicals of the present invention comprises a modified PV
5 to 3 parts of a polyhydric alcohol plasticizer per 100 parts by weight of A
It can be obtained by casting an aqueous solution containing 0 parts by weight or by melt-extrusion in the presence of water. At that time, if necessary, ordinary additives such as a coloring agent, a fragrance, an extender, an antifoaming agent, a release agent, an ultraviolet absorber, and an inorganic powder may be appropriately compounded. If necessary, ordinary water-soluble polymers such as PVA, starch, carboxymethylcellulose, methylcellulose, and hydroxymethylcellulose may be added as long as the characteristics of the present invention are not lost. Water-soluble films for packaging agricultural chemicals are used in hot and humid regions and cold regions, so that film strength and toughness are required, especially impact resistance at low temperatures. Because to reduce generally the glass transition point of the film that, polyhydric alcohols
A plasticizer is used. Specific plasticizers include
This includes polyhydric alcohols such as glycerin, diglycerin, and diethylene glycol. The addition amount of the polyhydric alcohol plasticizer is 5 to 30 parts by weight based on 100 parts by weight of the modified PVA.

The term "pesticide" as used in the present invention refers to an agent specified by the Agricultural Chemicals Control Law, and used for controlling animals and plants such as fungi, nematodes, mites, insects, rats, weeds, etc. that harm agricultural crops (including trees) or agricultural and forestry products. Fungicides, insecticides, herbicides, and other agents. Specifically, germicidal dispersants such as Bordeaux, soil and seed disinfectants such as chlorpicrin,
Insecticides such as organophosphorus and DDT, penetrant insecticides such as Schuldan, herbicides such as 2,4-D (2,4-dichlorophenoxyacetic acid), plant growth regulators such as naphthylacetic acid, pesticides, attractants Agents, repellents and the like. In addition, developing agents such as talc, kaolin and bentonite used as auxiliary agents for agricultural chemicals, synergists such as sulfoxide, and surfactants and dispersants for increasing the affinity of pesticides for water and dispersing them uniformly are also included. It is included in the pesticide of the present invention. The modified sulfonic acid group-containing PVA of the present invention and polyhydric alcohols
Pesticide unit-packed in water-soluble film using plasticizer
The packaging body can be used in various ways such as a wettable powder which is used by dissolving it in water and a jumbo agent which is directly injected into a field or a paddy field. The form can be a powder, a granule, or, in some cases, a liquid pesticide dissolved in an organic solvent.
Usually, pesticides are stored and transported in boxes or even aluminum outer bags, wrapped in several grams to several kilograms, and used on site.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In Examples, "%" and "parts" are based on weight unless otherwise specified. [Method of Measuring Water-Soluble (Complete Dissolution Time) of Water-Soluble Film] A film sample was cut into a square of 40 mm × 40 mm , and this was cut into a slide mount with scissors.
The film was immersed in water with stirring at ℃, and the time (number of seconds) until the film was completely dissolved was measured and evaluated. [Heat resistance] The film is heated at 140 ° C with a heat sealer at 1 kg / c.
Heat sealing was performed under the condition of m ² for 2 seconds, and the above-mentioned water solubility test was performed at 20 ° C. on the heat sealed portion.

Example 1 A methanol solution of a copolymer obtained by copolymerizing vinyl acetate and sodium 2-acrylamido-2-methylpropanesulfonate in a methanol solvent was prepared by adding a methanol solution of sodium hydroxide. A saponification reaction was carried out by a conventional method to obtain a modified sulfonic acid group-containing PVA having a degree of polymerization of 1720, a degree of saponification of 98 mol%, and a sulfonic acid group unit of 3 mol%. An aqueous solution was prepared using 20 parts of glycerin with respect to 100 parts of the modified PVA, and cast on a hot roll at 70 ° C. to obtain a film having a thickness of 40 μm. A bag of 10 cm × 20 cm was made from this film, and 40 g of a fine powder of a pesticide (pesticide, hydrate) was put therein and sealed by heat sealing. The pesticide packaging was further heat-sealed with a film in which aluminum foil was laminated on polyethylene to prevent water and plasticizer from scattering from the pesticide packaging bag. This bag was placed in a 50 ° C constant temperature bath as an accelerated test for a long-term storage test,
At week 4 and week 4 , the wrapped films were tested for water solubility over time. The heat-sealed portion of the removed film was tested for water solubility. Table 1 shows the results. Even after 4 weeks at 50 ° C., there was almost no decrease in water solubility, which was favorable.

Example 2 In the same manner as in Example 1, vinyl acetate and sodium 2-acrylamido-2-methylpropanesulfonate were copolymerized and a saponification reaction was carried out to obtain a degree of polymerization of 1250.
A modified sulfonic acid group-containing PVA having a degree of saponification of 88 mol% and a sulfonic acid group unit of 2 mol% was obtained. Using this modified PVA, a film was prepared, a pesticide was packaged, and a standing test was carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 3 In the same manner as in Example 1, vinyl acetate and sodium 2-acrylamido-2-methylpropanesulfonate were copolymerized and a saponification reaction was carried out to obtain a degree of polymerization of 1750.
A modified sulfonic acid group-containing PVA having a degree of saponification of 98 mol% and a sulfonic acid group unit of 6 mol% was obtained. Using this modified PVA, a film was prepared, a pesticide was packaged, and a standing test was carried out in the same manner as in Example 1. However, as a plasticizer added to the film, 15 parts of glycerin and 10 parts of diglycerin were used for 100 parts of PVA. The results are shown in Table 1.

Example 4 Example 1 was repeated except that the pesticide used in Example 1 was replaced with a disinfectant containing copper sulfate as a main component (including a copper wettable powder, zinc and magnesium ions). The packaging bag was subjected to a standing test in the same manner as described above, and the change in water solubility with time was observed. The results are shown in Table 1.

Comparative Example 1 A film was prepared and a pesticide was packaged in the same manner as in Example 1 except that unmodified PVA (polymerization degree: 1750, saponification degree: 88 mol%) was used as the PVA for the water-soluble film. The packaging bag was subjected to a standing test, and the change in water solubility with time was observed. The results are shown in Table 1.

Comparative Example 2 As a PVA for a water-soluble film, maleic acid-modified PV was used.
Except for using A (degree of polymerization 1780, degree of saponification 96 mol%, degree of modification 2 mol%), a film was prepared, a pesticide was wrapped, and a packaging bag was subjected to a standing test in the same manner as in Example 1 except that water was used. Changes in sex with time were observed. The results are shown in Table 1.

Comparative Example 3 A sodium allyl sulfonate was used in place of the monomer used in Example 1 as the sulfonic acid group-containing monomer.
Copolymerization with vinyl acetate and a saponification reaction were carried out in the same manner as in Example 1 to obtain an allylsulfonic acid group-containing modified P
VA was prepared. This modified PVA had a degree of polymerization of 250 and a degree of saponification of 88 mol%, and the degree of modification was 1.5 mol%. Using this modified PVA, a film was prepared in the same manner as in Example 1, the pesticide was wrapped, and a standing test was carried out. The strength of the film was extremely low, and the film was easily broken or cracked by a slight impact. As a water-soluble film for packaging agricultural chemicals, it was very poor in performance and could not be used at all. In order to improve the film strength of the allylsulfonic acid group-containing modified PVA, an attempt was made to increase the degree of polymerization of the modified PVA.
In the case of, the degree of polymerization could not be increased.
The results are shown in Table 1.

[0023]

[Table 1]

[0024]

The water-soluble film for packaging agricultural chemicals of the present invention comprises:
It has excellent mechanical strength and exhibits good water solubility even when the agricultural chemical is packaged and left for a long period of time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08F 220: 56) C08L 29:04

Claims (3)

(57) [Claims] A sulfonic acid group unit represented by the following chemical formula 1 is contained in an amount of 0.5 to 10 mol%, and a viscosity average polymerization degree is 500 to 1.
4000, 100 parts by weight of a modified polyvinyl alcohol having a saponification degree of 70 to 99.5 mol% , and polyhydric alcohols
A film containing 5 to 30 parts by weight of a plasticizer,
A water-soluble film for packaging agricultural chemicals , wherein the complete dissolution time after packaging the agricultural chemical is 30 seconds or less . Embedded image (Where R ¹ is a hydrogen atom or a lower alkyl group, R ² is an alkyl group, R ³ , R ⁴ , and R ⁵ are a hydrogen atom or an alkyl group, M is a hydrogen atom, an alkali metal, an ammonium group, or an amine group. Shown.) 2. The sulfonic acid group unit is 2-acrylamido-2-methylpropanesulfonic acid or an alkali metal salt thereof, 2-acrylamido-1-methylpropanesulfonic acid or an alkali metal salt thereof, or 2-methacrylamido-2-. The water-soluble film for agricultural chemical packaging according to claim 1, which is a unit selected from methylpropanesulfonic acid or an alkali metal salt thereof. 3. A water-soluble film according to claim 1.
Pesticide package with pesticide packaged in a bag.