JP5812611B2 - Seed packaging using polyvinyl alcohol polymer film - Google Patents

Description

  The present invention relates to a seed package that is preferably used for sowing seeds such as vegetables, wherein the seed is wrapped with a polyvinyl alcohol (hereinafter, “polyvinyl alcohol” may be abbreviated as “PVA”) polymer film, The present invention also relates to a PVA polymer film used for the seed package.

  Conventionally, seeds such as vegetables are wrapped with a long water-soluble or biodegradable film or porous sheet to form a band-like (including tape or sachet-like shape) or string-like seed package, Is a method of sowing seeds by placing them on soil such as farmland typified by a field and covering the soil from above if necessary (see, for example, Patent Documents 1 to 4). . In the sowing method, the film or porous sheet is dissolved (disassembled) by water that has penetrated into the soil due to irrigation or rain, or the film or porous sheet is decomposed by bacteria in the soil. Encapsulated seeds are exposed and grow (germinate). By using such a seed package, the number and interval of seeds to be sown per unit area can be made constant even without special equipment or skill. Can be eliminated, and conversely, inefficient operation of the farmland due to the insufficient number of seeds to be sown can be prevented. As the material of the film, a PVA polymer having unique characteristics of water solubility and biodegradability is used.

  Conventionally, it is considered important for PVA polymer films used for seed packaging as described above to be quickly dissolved by water in the soil. From this point of view, for example, two types of saponification degrees are different. There has been proposed a PVA-based polymer film having good water solubility obtained by blending these PVA (see Patent Document 5).

Japanese Utility Model Publication No. 38-21220 Japanese Patent Publication No. 40-25841 Japanese Utility Model Publication No. 45-8659 Japanese Utility Model Publication No. 52-104818 JP 2002-275339 A

  However, for seeds having a relatively small seed size and weak germination, such as seeds of cruciferous plants, sufficient germination rate (normal with respect to the number of seeds sown) Ratio of the number of germinated buds) may not be obtained, and seeds were wasted or seeds that were sown did not germinate, and farmland could not be operated efficiently. Therefore, there has been a demand for a seed package that shows a good germination rate even for seeds with weak germination ability.

  Therefore, the present invention provides a seed package that wraps seeds with a long PVA polymer film and can show a good germination rate even for seeds with low germination ability, and a long package used for the seed package. An object of the present invention is to provide a PVA polymer film.

  As a result of intensive studies to achieve the above object, the present inventor uses a long PVA polymer film in which the solubility in water and the shrinkage rate when floated on the water surface are in specific ranges, respectively. As a result, the inventors have found that the above-described object can be achieved, and have further studied based on the findings to complete the present invention.

That is, the present invention
[1] A seed package in which seeds are wrapped with a long PVA polymer film, and the PVA polymer film has a dissolution time of 5 to 30 seconds when immersed in water at 5 ° C. A seed package having a shrinkage ratio in the length direction of 15% or less when floated on the water surface at 20 ° C.,
[2] The above, wherein the PVA polymer film contains 1 to 30 parts by mass of at least one of starch (B) and inorganic powder (C) with respect to 100 parts by mass of the PVA polymer (A). [1] seed package,
[3] The seed package according to [2], wherein the inorganic powder (C) is at least one selected from the group consisting of talc, silica, titanium dioxide, and calcium carbonate,
[4] The seed package according to any one of the above [1] to [3], wherein the seed is a seed of a cruciferous plant.
[5] A long PVA polymer film for wrapping seeds into a seed wrap, having a dissolution time of 5 to 30 seconds when immersed in water at 5 ° C., on the water surface at 20 ° C. A PVA polymer film having a shrinkage in the length direction of 15% or less when floated,
About.

  ADVANTAGE OF THE INVENTION According to this invention, the seed package which can show a favorable germination rate even with a seed with weak germination power is obtained.

The present invention is described in further detail below.
The seed package of the present invention is obtained by wrapping seeds with a long PVA polymer film. As the PVA polymer (A) constituting the PVA polymer film, a polymer produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer can be used. Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, and the like. Among these, vinyl acetate is preferable.

  The vinyl ester polymer is preferably obtained by using only one or two or more vinyl ester monomers as a monomer, and using only one vinyl ester monomer as a monomer. Although what was obtained is more preferable, the copolymer of 1 type, or 2 or more types of vinyl-ester type monomers and the other monomer copolymerizable with this may be sufficient.

  Other monomers copolymerizable with such vinyl ester monomers include, for example, ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene and isobutene; acrylic acid or salts thereof; methyl acrylate, acrylic Ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, etc. Acrylic acid ester; methacrylic acid or salt thereof; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methacrylic acid 2-ethylhexyl, dodecyl methacrylate Methacrylic acid esters such as octadecyl methacrylate; acrylamide, N-methyl acrylamide, N-ethyl acrylamide, N, N-dimethyl acrylamide, diacetone acrylamide, acrylamide propane sulfonic acid or salt thereof, acrylamidopropyldimethylamine or salt thereof, N- Acrylamide derivatives such as methylolacrylamide or derivatives thereof; methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or salt thereof, methacrylamidepropyldimethylamine or salt thereof, N-methylolmethacrylamide or salt thereof Methacrylamide derivatives such as derivatives; N such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone Vinyl amides; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether; cyan such as acrylonitrile and methacrylonitrile Vinyl halides; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid or salts thereof, esters or acid anhydrides; itaconic acid or salts thereof; Examples thereof include esters or acid anhydrides; vinylsilyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate. Said vinyl ester polymer can have a structural unit derived from 1 type (s) or 2 or more types among these other monomers.

  The proportion of the structural units derived from the other monomers in the vinyl ester polymer is not particularly limited as long as the object of the present invention is not impaired, but the moles of all structural units constituting the vinyl ester polymer are not limited. Based on the number, it is preferably 15 mol% or less, and more preferably 5 mol% or less.

The degree of polymerization of the PVA polymer (A) is not necessarily limited, but since the film strength tends to decrease as the degree of polymerization decreases, it is preferably 200 or more, more preferably 300 or more, It is more preferably 400 or more, and particularly preferably 500 or more. Moreover, since water solubility tends to decrease when the degree of polymerization is too high, it is preferably 5000 or less, more preferably 3000 or less, further preferably 2000 or less, and 1000 or less. Is particularly preferred. In addition, the polymerization degree of the PVA polymer in this specification means the average polymerization degree measured according to the description of JIS K6726-1994, and the polymerization degree of the PVA polymer (A) is the PVA polymer. After re-saponifying (A) and refining, it can be calculated from the intrinsic viscosity [η] (unit: deciliter / g) measured in water at 30 ° C. by the following equation.
Po = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

  In the present invention, since the PVA polymer film needs to be soluble in water at a temperature below room temperature, the saponification degree of the PVA polymer (A) is preferably 95 mol% or less. If the degree of saponification exceeds 95 mol%, the water solubility of the PVA polymer film may be insufficient. The saponification degree of the PVA polymer (A) is more preferably 93 mol% or less, and still more preferably 91 mol% or less. The degree of saponification of the PVA polymer (A) is preferably 65 mol% or more, more preferably 70 mol% or more, and further preferably 75 mol% or more. Here, the degree of saponification of the PVA polymer (A) is a structural unit (typically a vinyl ester monomer unit) and a vinyl alcohol unit that the PVA polymer (A) can convert into a vinyl alcohol unit by saponification. The ratio of the number of moles of the vinyl alcohol unit to the total number of moles (mol%). The degree of saponification of the PVA polymer (A) can be measured according to the description of JIS K6726-1994. As will be described later, when the PVA polymer (A) is a blend of two or more PVA polymers, the degree of saponification is based on the whole blend of the two or more PVA polymers. As required.

  The PVA polymer (A) constituting the PVA polymer film may be composed of only one type of PVA polymer, or two types having different degrees of polymerization, degree of saponification, type of modification and amount of modification. It may be a blend of the above PVA polymers. In particular, in the case of a blend of two or more PVA polymers having different degrees of polymerization, the difference in the degree of polymerization of at least two PVA polymers of the two or more PVA polymers is 800. If it is above, the reason is not clear, but it is preferable because the germination rate of seeds tends to be improved as compared with the case of only one type of PVA polymer.

  When the PVA polymer film contains 1 to 30 parts by mass of at least one of starch (B) and inorganic powder (C) with respect to 100 parts by mass of the PVA polymer (A), the germination rate of seeds Can be improved. Although details are not necessarily clear, it is assumed that this is because the PVA polymer film easily disintegrates when dissolved in the soil, and the amount of the PVA polymer film remaining around the seeds is reduced. . When the content of at least one of the starch (B) and the inorganic powder (C) is less than 1 part by mass with respect to 100 parts by mass of the PVA polymer (A), the above effect can be sufficiently obtained. There may not be. In this respect, the content of at least one of the starch (B) and the inorganic powder (C) is more preferably 2 parts by mass or more with respect to 100 parts by mass of the PVA polymer (A). More preferably, it is at least part. When the content of at least one of starch (B) and inorganic powder (C) exceeds 30 parts by mass with respect to 100 parts by mass of PVA polymer (A), There exists a possibility that intensity | strength and a softness | flexibility may be impaired or it may become easy to produce faults, such as a pinhole, in film forming of a PVA-type polymer film. From this viewpoint, the content of at least one of the starch (B) and the inorganic powder (C) is more preferably 20 parts by mass or less with respect to 100 parts by mass of the PVA polymer (A), and 15 parts by mass. More preferably, it is at most parts.

  Examples of the starch (B) include natural starch such as corn starch and potato starch; etherified starch, esterified starch, cross-linked starch, grafted starch, baked dextrin, enzyme-modified dextrin, pregelatinized starch, oxidized starch And modified starch. Starch (B) may be used individually by 1 type, or may use 2 or more types together. Among these, natural starch is preferable from the viewpoint of price and availability.

  Examples of the inorganic powder (C) include talc, silica, titanium dioxide, calcium carbonate, carbon black, glass fiber, mica, and wollastonite. Inorganic powder (C) may be used individually by 1 type, or may use 2 or more types together. Among these, at least one selected from the group consisting of talc, silica, titanium dioxide, and calcium carbonate is preferable from the viewpoints of dispersibility, price, availability, film appearance, and the like in the PVA polymer.

  Either one of the starch (B) and the inorganic powder (C) may be used, or both may be used together, but when either one is used, the inorganic powder compared to the starch (B). The body (C) is preferable because the germination rate of the seed can be improved with a smaller amount.

  PVA polymer films are more rigid than other plastic films when they do not contain a plasticizer, and may have problems with mechanical properties such as impact strength and processability during secondary processing. In order to prevent this problem, it is generally performed that a PVA polymer film contains a plasticizer (D). In addition, if the kind and amount of the plasticizer (D) are appropriately selected, the solubility of the PVA polymer film in water can be controlled.

  A polyhydric alcohol can be preferably used as the plasticizer (D). Examples of the polyhydric alcohol include ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane. These plasticizers (D) may be used alone or in combination of two or more. Among these plasticizers, ethylene glycol or glycerin is preferable from the viewpoint of compatibility with PVA-based polymers and availability.

  It is preferable that content of the plasticizer (D) in a PVA-type polymer film exists in the range of 1-30 mass parts with respect to 100 mass parts of PVA-type polymers. If content of a plasticizer (D) is less than 1 mass part with respect to 100 mass parts of PVA-type polymers, there exists a possibility that said effect may not fully be acquired. In this respect, the content of the plasticizer (D) is more preferably 3 parts by mass or more and further preferably 5 parts by mass or more with respect to 100 parts by mass of the PVA polymer. Moreover, when content of a plasticizer (D) exceeds 30 mass parts with respect to 100 mass parts of PVA-type polymers, a plasticizer (D) bleeds out on the surface of a PVA-type polymer film, or PVA-type In some cases, the polymer film becomes too flexible and the handleability is lowered. In this respect, the content of the plasticizer (D) is more preferably 25 parts by mass or less, and further preferably 20 parts by mass or less with respect to 100 parts by mass of the PVA polymer.

  When forming a PVA polymer film using a liquid medium such as water as described later, the PVA polymer film tends to adhere to the film forming apparatus when the content of the liquid medium is high. This may cause problems such as film surface defects. In general, the slip property between PVA polymer films is not as good as that of other plastic films, so wrinkles are generated when winding into a roll shape, or there is a problem with process passability when wrapping seeds. May occur. In order to prevent these problems, it is preferable to contain the surfactant (E) in the PVA polymer film or the film forming stock solution used for forming the PVA polymer film. Although there is no restriction | limiting in particular in the kind of surfactant (E) used, For example, anionic surfactant, nonionic surfactant, etc. are mentioned.

  Examples of the anionic surfactant include carboxylic acid types such as potassium laurate; sulfate ester types such as octyl sulfate; and sulfonic acid types such as dodecylbenzene sulfonate. Nonionic surfactants include, for example, alkyl ether types such as polyoxyethylene oleyl ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate; polyoxyethylene laurylamino Alkylamine type such as ether; alkylamide type such as polyoxyethylene lauric acid amide; polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; alkanolamide type such as lauric acid diethanolamide and oleic acid diethanolamide; polyoxy Examples include allyl phenyl ether type such as alkylene allyl phenyl ether. Surfactant may be used individually by 1 type, or may use 2 or more types together. Among these surfactants, nonionic surfactants are preferable because they are excellent in reducing the film surface abnormality during film formation.

  The content of the surfactant (E) in the film-forming stock solution used for forming the PVA-based polymer film or the PVA-based polymer film is 0.001 to 100 parts by mass of the PVA-based polymer (A). It is preferably in the range of 1 part by mass, more preferably in the range of 0.005 to 0.7 part by mass, and still more preferably in the range of 0.01 to 0.5 part by mass. If the content is less than 0.001 part by mass, the effect of reducing the abnormality of the film surface during film formation is difficult to appear, and if it is more than 1 part by mass, it elutes on the surface of the PVA polymer film and conversely causes blocking. There is a fear.

  The PVA polymer film requires other components than the PVA polymer (A), starch (B), inorganic powder (C), plasticizer (D), and surfactant (E). Depending on the above, it may be included in a range not inhibiting the effects of the present invention. Such other components include, for example, moisture, antioxidants, ultraviolet absorbers, lubricants, colorants, fillers, preservatives, antifungal agents, fertilizers (effective ingredients for seed growth), pesticides, and the like Other polymer compounds other than the above components may be mentioned. The content of the other component in the PVA polymer film is preferably 50% by mass or less, more preferably 20% by mass or less, although it depends on the type of the other component. More preferably, it is at most mass%.

  The size of the PVA polymer film is not particularly limited as long as it is long, and various changes can be made depending on the use form of the seed package, but the state immediately before the seed is packaged (as described later, the PVA polymer The value obtained by dividing the length of the film by the width is preferably 5 or more, more preferably 30 or more in the state before folding when the film is folded in half. Although there is no restriction | limiting in particular in the upper limit of the said value, It is preferable that the said value is 1,000,000 or less. The width of the PVA polymer film varies depending on the type of seed, the packaging method, the use form of the seed packaging, and the like, for example, within the range of 0.5 to 20 cm in the state immediately before packaging the seed. Is preferable, and it is more preferable that it is in the range of 1 to 10 cm. The length of the PVA polymer film is preferably 30 cm or more, and more preferably 1 m or more. Although there is no restriction | limiting in particular in the upper limit of the length of a PVA-type polymer film, It is preferable that the said length is 10,000 m or less.

  Although there is no restriction | limiting in particular in the thickness of a PVA-type polymer film, There exists a tendency for water solubility to fall, so that thickness is thick, From this viewpoint, it is preferable that thickness is 50 micrometers or less, It is more preferable that it is 40 micrometers or less, 30 micrometers More preferably, it is as follows. In addition, when the thickness is too thin, there is a possibility that a problem may occur in the handling property and strength of the PVA polymer film. Therefore, the thickness is preferably 5 μm or more, more preferably 8 μm or more, and preferably 10 μm or more. Further preferred. In addition, the thickness of a PVA polymer film measures the thickness of arbitrary 10 places (for example, arbitrary 10 places on the straight line drawn in the length direction of a PVA polymer film), and calculates | requires them as an average value. be able to.

  In the present invention, it is necessary that the dissolution time when the PVA polymer film is immersed in water at 5 ° C. is in the range of 5 to 30 seconds. In the case of the PVA polymer film having a dissolution time of less than 5 seconds, blocking is caused by the PVA polymer film wound in a roll shape, or handling becomes difficult when the seed is wrapped with the PVA polymer film. Prone to problems. From this viewpoint, the dissolution time is preferably 7 seconds or longer, and more preferably 9 seconds or longer. On the other hand, when the dissolution time exceeds 30 seconds, there is a possibility that a sufficient germination rate may not be obtained with a seed having a relatively small seed size and a weak germination ability, such as a seed of a cruciferous plant. From this viewpoint, the dissolution time is preferably 20 seconds or shorter, more preferably 18 seconds or shorter, and further preferably 16 seconds or shorter.

In the present invention, the dissolution time when the PVA polymer film is immersed in water at 5 ° C. can be measured as follows.
<1> Place a long PVA polymer film to be measured, obtained by disassembling the seed wrapping body, in a constant temperature and humidity chamber adjusted to 20 ° C.-65% RH for 16 hours or longer. Moisten.
<2> A rectangular sample with a length of 40 mm and a width of 10 mm was cut out from the conditioned film, and a rectangular plate (hole) with a length of 35 mm and a width of 23 mm was opened on a 50 mm x 50 mm plastic plate. In addition, the sample is sandwiched and fixed so that the length direction of the sample is parallel to the length direction of the window and the sample is positioned substantially at the center in the width direction of the window.
<3> Pour 300 ml of water into a 500 ml beaker, and adjust the water temperature to 5 ° C. while stirring with a magnetic stirrer equipped with a 3 cm long bar at 280 rpm.
<4> The sample fixed to the plastic plate in <2> above is immersed in a beaker, taking care not to contact the magnetic stirrer bar.
<5> Measure the time until the sample pieces dispersed in water disappear completely after being immersed in water.

  The above dissolution time is the type and amount of additives such as the type of PVA polymer (A) used (degree of polymerization, degree of saponification, type of modification, amount of modification, etc.), film thickness, plasticizer (D), etc. The above range can be easily adjusted by appropriately adjusting the film forming method and its conditions. Specifically, for example, in the PVA polymer (A) to be used, the degree of polymerization is lowered; the degree of saponification is lowered; a modified species (a structural unit derived from another monomer copolymerizable with the vinyl ester monomer described above) Adopting a more hydrophilic material as the type)); increasing the amount of modification or reducing the thickness of the PVA polymer film; adopting a more hydrophilic material as the plasticizer (D) The dissolution time can be shortened by increasing the content of the plasticizer (D); weakening the heat treatment conditions for the film, and the like.

  Moreover, the shrinkage | contraction rate of the length direction (longitudinal direction of a long PVA polymer film) of a PVA polymer film when a PVA polymer film floats on the water surface of 20 degreeC is 15% or less. However, it is particularly important from the viewpoint of germination rate. The details are not necessarily clear, but when the PVA polymer film starts to dissolve in the soil, if the PVA polymer film has a large shrinkage rate, the PVA polymer aggregates and remains around the seeds. It is presumed to inhibit seed germination. In this respect, the shrinkage rate is preferably 10% or less, more preferably 7% or less, and further preferably 5% or less.

In the present invention, the shrinkage in the length direction when the PVA polymer film is floated on the water surface at 20 ° C. can be measured as follows.
<1> Place a long PVA polymer film to be measured, obtained by disassembling the seed wrapping body, in a constant temperature and humidity chamber adjusted to 20 ° C.-65% RH for 16 hours or longer. Moisten.
<2> A rectangular sample having a length of 150 mm and a width of 10 mm is cut out from the conditioned film.
<3> Water is spread on the container to a depth of 5 to 10 cm so that the water surface has an area of 15 cm × 20 cm or more, and is placed in a 20 ° C. room and left until the water temperature reaches 20 ° C.
<4> Gently float the above sample on the surface of water at 20 ° C. without bending.
<5> The length of the side when the 150 mm side of the sample is the shortest in the time from when the sample floats on the surface of the water (hereinafter referred to as “minimum length”) ). In addition, when a sample bends after it floats on the water surface and melt | dissolves, let the linear distance between the vertexes which comprise the both ends of a 150-mm edge | side (the shorter one of two) be the length of a side. From the obtained minimum length and the length before floating on the water surface (150 mm), the shrinkage rate is calculated by the following formula.
Shrinkage rate (%) = 100 × ([Length before floating on water surface] − [Minimum length]) / [Length before floating on water surface]
In addition, when the sample spreads without contracting when it floats on the water surface, the contraction rate is set to 0%.

  In the present invention, as a specific method for producing a PVA polymer film, for example, a PVA polymer (A) and, if necessary, the above-mentioned starch (B), inorganic powder (C), plastic Casting film-forming method, wet method using a film-forming stock solution in which at least one of agent (D), surfactant (E) and other components is dissolved and / or dispersed in a liquid medium such as water Film-forming method (discharge into poor solvent), dry-wet film-forming method, gel film-forming method (method for obtaining a PVA polymer film by extracting and removing the solvent after the film-forming stock solution is once cooled and gelled), Alternatively, a film forming method combining these, or a PVA polymer (A) impregnated with a liquid medium such as water and, if necessary, the above-mentioned starch (B), inorganic powder (C), plasticizer ( D), at least of surfactant (E) and other ingredients Melted by supplying seeds and the like extruder, a film-forming solution obtained such melt extrusion film formation method for forming a film by extruding the like T-die, it is possible to employ any method. Among these, the casting film forming method and the melt extrusion film forming method are preferable because a PVA polymer film having high transparency and little coloring can be obtained.

  The concentration of volatile components in the film-forming stock solution (concentration of volatile components such as a solvent removed by volatilization or evaporation at the time of film formation) is preferably in the range of 50 to 90% by mass. It is more preferable to be within the range. If the volatile concentration is less than 50% by mass, the viscosity may increase and film formation may be difficult. On the other hand, when the volatile content concentration exceeds 90% by mass, the thickness uniformity of the PVA polymer film that can be obtained by lowering the viscosity may be impaired.

  There is no restriction | limiting in particular in the preparation method of said film forming undiluted | stock solution, For example, PVA polymer (A) is melt | dissolved in liquid media, such as water, and above-mentioned starch (B) and inorganic substance powder (C) as needed. , A method of adding at least one of a plasticizer (D), a surfactant (E) and other components, or a PVA polymer impregnated with a liquid medium such as water using an extruder (A ), And if necessary, melt and knead together at least one of the above-mentioned starch (B), inorganic powder (C), plasticizer (D), surfactant (E) and other components. The method of doing is mentioned. Among these, the former method is preferable from the viewpoint of uniform dissolution and / or dispersion of the components used.

  When a PVA polymer film is formed by the casting film forming method or the melt extrusion film forming method using the above film forming stock solution, it is cast or extruded as it passes through each step of the film forming apparatus. The moisture content of the film gradually decreases and is finally processed into a dried film. The processing conditions at this time are as follows: when the obtained PVA polymer film is floated on the water surface at 20 ° C. This affects the shrinkage rate in the length direction.

  That is, in order to avoid problems such as meandering in the film transport roll and wrinkles in the winding process in the film forming process, generally, a certain tension is applied to the film, but if this tension is excessive, or In the case of inflation film forming in the melt extrusion film forming method or film formation of intentional uniaxially or biaxially stretched film, a residual stress is generated in the film after film formation, and the shrinkage rate of the film is increased when it floats on the water surface. .

  Therefore, for example, when a PVA polymer film is continuously produced by a casting film forming method or a melt extrusion film forming method, a film on a support (cast roll, belt, etc.) on which a film forming stock solution is discharged from a die. The length of the shrinkage rate in the length direction is within the above range that the winding rate (stretching ratio) of the finally formed PVA polymer film with respect to the speed of the film is 1.5 times or less. The PVA polymer film can be obtained efficiently and is preferred. Even when not continuously produced, the stretching ratio in the length direction of the long PVA polymer film (the ratio of the length after stretching to the length before stretching) is 1.5 times or less. It is preferable that a long PVA polymer film having a shrinkage in the length direction within the above range can be obtained efficiently. In the long PVA polymer film, the shrinkage ratio in the length direction can be more efficiently within the above range, and thus the draw ratio is more preferably 1.3 times or less, and 1.1 times. It is more preferable that it is as follows, and it is particularly preferable that it is substantially 1.0 times.

  In addition, it is preferable to apply an appropriate heat treatment to the film after film formation because the shrinkage stress remaining on the film can be relaxed. However, the heat treatment temperature is preferably in the range of 50 to 160 ° C., and preferably in the range of 60 to 150 ° C., because the water solubility of the film may decrease when excessive heat treatment is performed. More preferably, it is still more preferably in the range of 70 to 140 ° C. Although the heat treatment time depends on the heat treatment temperature, the heat treatment can be performed efficiently, and a PVA polymer film with little deterioration in water solubility and little deterioration can be obtained efficiently. It is preferably within the range of ˜300 seconds, more preferably within the range of 0.2 to 250 seconds, and even more preferably within the range of 0.5 to 200 seconds.

  The PVA polymer film formed as described above is slit into a certain width to form a tape-like PVA polymer film (long PVA polymer film), and then the tape-like PVA polymer film By wrapping seeds with a coalesced film, a seed package can be obtained. There are no particular restrictions on how to wrap the seeds. For example, the tape-like PVA polymer film is folded in half (longitudinal direction), and seeds are placed at regular intervals in the resulting valleys. A method of twisting the PVA polymer film so that the seed is encapsulated; the seeds are placed on the tape-like PVA polymer film at regular intervals, and the tape-like PVA polymer film is placed so that the seeds are encapsulated. A method of rounding into a cylindrical shape and further entwining a thread such as a biodegradable thread to improve strength and workability; placing seeds at regular intervals between two tape-like PVA polymer films; Known methods such as a method of sandwiching seeds by fixing two tape-like PVA polymer films with an adhesive or the like can be employed. By these methods, a band-like or string-like seed package can be obtained.

  There are no particular restrictions on the type of seeds packaged in the present invention, but when there is a factor that inhibits germination because the seed size is relatively small and the germination power is weak, such as the seeds of cruciferous plants. In particular, the seed is preferably a seed of a cruciferous plant because the effect of the present invention is particularly remarkable in a seed that easily leads to a decrease in germination rate. Examples of the Brassicaceae plants include rape, Mizuna, turnip, Nozawana, Komatsuna, Pakchoi, Chingensai, Chinese cabbage and the like. The seed used in the present invention may be a plant other than the Brassicaceae such as carrot.

  EXAMPLES The present invention will be specifically described below with reference to examples and the like, but the present invention is not limited to these examples. In addition, each measuring method of the dissolution time when immersed in water at 5 ° C. and the shrinkage rate in the length direction when floated on the water surface at 20 ° C., which was employed in the following examples, comparative examples and control examples Is shown below.

Dissolution time when immersed in water at 5 ° C. The humidity of the seed packaging film obtained in Examples, Comparative Examples, or Control Examples below is placed in a thermo-hygrostat adjusted to 20 ° C.-65% RH for 20 hours. did. A rectangular sample with a length of 40 mm and a width of 10 mm was cut out from the conditioned film, and a sample of a rectangular plate (hole) with a length of 35 mm and a width of 23 mm on a 50 mm × 50 mm plastic plate was placed between the two sheets. The sample was sandwiched and fixed so that its length direction was parallel to the length direction of the window and the sample was positioned substantially at the center in the width direction of the window.
On the other hand, 300 ml of water is put into a 500 ml beaker, the water temperature is adjusted to 5 ° C. while stirring with a magnetic stirrer equipped with a 3 cm long bar at 280 rpm, and the sample fixed on the plastic plate is magnetically It was immersed in a beaker, being careful not to contact the stirrer bar. The time until the sample piece dispersed in water completely disappeared after being immersed in water was measured, and this was taken as the dissolution time.

Shrinkage in the lengthwise direction when floated on the water surface at 20 ° C. The temperature of the seed packaging film obtained in Examples, Comparative Examples or Control Examples below 20 ° C. in a constant temperature and humidity chamber adjusted to 20 ° C.-65% RH for 20 hours. Placed and conditioned. A rectangular sample having a length of 150 mm and a width of 10 mm was cut out from the conditioned film.
On the other hand, the water surface is stretched to a depth of 8 cm so that the water surface has an area of 15 cm × 20 cm or more, placed in a room at 20 ° C. and allowed to stand until the water temperature reaches 20 ° C., and then on the water surface. The above sample was floated gently while avoiding bending. In the time from when the sample floated on the water surface until the sample was dissolved, the length (minimum length) of the side when the 150 mm side of the sample was the shortest was measured. From the obtained minimum length and the length before floating on the water surface (150 mm), the shrinkage rate was calculated by the following formula.
Shrinkage rate (%) = 100 × ([Length before floating on water surface] − [Minimum length]) / [Length before floating on water surface]
In addition, when the sample spreads without contracting when floated on the water surface, the contraction rate was set to 0%.

[Control Example 1]
Culture soil was put in a plastic planter of 20 cm × 70 cm, and three grooves of about 6 mm depth were dug in the longitudinal direction of the planter. The spacing between the grooves was about 5 cm. Turnip seeds (Takii Seedling Co., Ltd .: Turnip / Disease Hikari) were placed in this groove as they were at intervals of about 5 cm, and lightly soiled on the seeds. The number of seeds was 12 per groove. Therefore, the number of seeds per planter is 36. Two of these planters were prepared and placed on the east side window of the room, which was temperature-controlled at 23 ° C. from April 1, and an appropriate amount of water was given every day. Two weeks later, the number of germinating seeds was counted and found to be 70. Therefore, the germination rate is 97%.

[Example 1]
100 parts by mass of PVA (polyvinyl acetate saponified product) having a polymerization degree of 1700 and a saponification degree of 88.5 mol%, 10 parts by mass of talc (average particle size 80 μm), 14 parts by mass of glycerin and a surfactant (diethanolamine laurate) D) 0.1 part by mass is put in 900 parts by mass of deionized water at room temperature, heated to 90 ° C. with stirring using a water bath, and stirred for 2 hours after reaching 90 ° C. Was made. This PVA aqueous solution was cast on a metal roll having a surface temperature of 60 ° C. (the surface was mirror-finished with hard chrome plating), held for 30 minutes as it was, and dried to form a film. This film was fixed to a metal frame with a clip while applying no tension, and heat-treated at 120 ° C. for 2 minutes in a hot air dryer to obtain a heat-treated PVA film having a thickness of 18 μm.
The obtained PVA film was cut into a film length (length in the film forming direction) of 350 mm × film width of 15 mm to form a seed packaging film, and the dissolution time when immersed in water at 5 ° C. according to the method described above and The shrinkage in the length direction when floating on the water surface at 20 ° C. was measured. The results are shown in Table 1. In the measurement of the contraction rate in the length direction when floating on the water surface at 20 ° C., the film was dissolved without contracting at all.

  Another seed packaging film (film length 350 mm × film width 15 mm) obtained in the same manner as described above, the same seed as used in Control Example 1 is spaced by about 5 cm, one by one, in the vicinity of the center of 15 mm width. (6 in total), roll the seed wrapping film into a cylinder while preventing seeds from spilling, and lightly wrap the area around with a rayon thread to produce a string-like seed package of about 350 mm in length did. Twelve similar ones were produced. Next, similarly to the control example 1, the culture soil was put into a 20 cm × 70 cm plastic planter, and three grooves having a depth of about 6 mm were dug in the longitudinal direction of the planter at an interval of about 5 cm, and the seed package produced in this groove Were placed in series per groove, and lightly soiled on top. Two of these planters were prepared and placed on the east side window of the room, which was temperature-controlled at 23 ° C. from April 1, and an appropriate amount of water was given every day. Two weeks later, the number of germinating seeds was counted and found to be 66. Therefore, the germination rate is 92%.

[Example 2]
In Example 1, instead of using 100 parts by mass of PVA chips having a degree of polymerization of 1700 and a degree of saponification of 88.5 mol%, 30 parts by mass of PVA chips having a degree of polymerization of 1700 and a degree of saponification of 88.5 mol% and a degree of polymerization were used. A heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 1 except that a mixture of 500 parts of PVA chips having a saponification degree of 88.7 mol% was used.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
In Example 2, a heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 2 except that the amount of talc added was changed from 10 parts by mass to 4 parts by mass with respect to 100 parts by mass of the PVA chip. .
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
A heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 1 except that talc, glycerin and surfactant were not added.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 5]
In Example 2, a heat-treated PVA film was obtained in the same manner as in Example 2 except that the thickness of the film was changed from 18 μm to 12 μm.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 6]
A heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 1 except that talc was not added.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 7]
A heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 1 except that the heat treatment temperature was changed from 120 ° C. to 80 ° C. in Example 1.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 8]
In Example 1, a heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 1 except that 10 parts by mass of silica (average particle size 30 μm) was used instead of 10 parts by mass of talc.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 9]
A heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 1 except that 10 parts by weight of corn starch (average particle size 70 μm) was used instead of 10 parts by weight of talc.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, a heat-treated PVA film was obtained in the same manner as in Example 1 except that the thickness of the film was changed from 18 μm to 60 μm.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, instead of using 100 parts by mass of PVA chips having a polymerization degree of 1700 and a saponification degree of 88.5 mol%, 70 parts by mass of PVA chips having a polymerization degree of 1300 and a saponification degree of 93.5 mol% and a polymerization degree were used. A heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 1 except that a mixture of 500 parts of PVA chips having a saponification degree of 88.7 mol% was used.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
The aqueous PVA solution produced in Example 2 was cast and dried on a metal roll in the same manner as in Example 1 to form a film having a thickness of 35 μm. The film was fixed to a metal frame with a clip while being stretched 2.0 times in the longitudinal direction of the film (rotating direction of the metal roll), and heat-treated at 120 ° C. for 2 minutes in a hot air dryer. . Therefore, the draw ratio of the film in the length direction in the seed packaging film is 2.0 times. The thickness of the obtained heat-treated PVA film was 18 μm.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
60 parts by mass of PVA chips having a degree of polymerization of 800 and a saponification degree of 72.1 mol%, 40 parts by mass of PVA chips having a degree of polymerization of 2400 and a degree of saponification of 78.4 mol%, 25 parts by mass of corn starch (average particle size 70 μm) and As a plasticizer, 5 parts by mass of polyethylene glycol was placed in 900 parts by mass of deionized water at room temperature, and an aqueous PVA solution was prepared in the same manner as in Example 1. This PVA aqueous solution was cast and dried on a metal roll in the same manner as in Example 1 to form a film having a thickness of 30 μm. The film was fixed to a metal frame with a clip while being stretched to a length of 2.0 times in the longitudinal direction of the film (rotating direction of the metal roll), and heat-treated at 105 ° C. for 8 minutes in a hot air dryer. . Therefore, the draw ratio of the film in the length direction in the seed packaging film is 2.0 times. The thickness of the obtained heat-treated PVA film was 15 μm.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 5]
In Example 2, a heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 2 except that the heat treatment temperature was changed from 120 ° C. to 200 ° C.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 10]
30 parts by mass of PVA chips having a polymerization degree of 1700 and a degree of saponification of 88.5 mol%, 70 parts by mass of PVA chips having a degree of polymerization of 500 and a degree of saponification of 88.7 mol%, 10 parts by mass of talc (average particle size 80 μm), glycerin A mixture obtained by dry blending 14 parts by mass and 0.1 parts by mass of a surfactant (lauric acid diethanolamide) was impregnated with 170 parts by mass of water, melt-kneaded at an extrusion temperature of 150 ° C. by a twin screw extruder, and defoamed. Thereafter, the obtained PVA melt was melt extruded from a T die onto a metal roll having a surface temperature of 90 ° C. The running speed of the film on the metal roll surface (linear speed on the roll surface) was 5.0 m / min. The film solidified on the metal roll was heat-dried and then heat-treated at 105 ° C. for 0.5 minutes, and was wound into a roll by a take-up roll. The running speed of the film on the take-up roll was 5.5 m / min. Therefore, the magnification (stretching ratio) of the traveling speed of the film on the winding roll with respect to the traveling speed of the film on the metal roll is 1.1 times. The thickness of the obtained heat-treated PVA film was 18 μm.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 6]
In Example 10, the extrusion rate of the PVA melt onto the metal roll was 1.6 times that of Example 10, and the running speed of the film on the take-up roll was changed from 5.5 m / min to 9.0 m / min. A heat-treated PVA film having a thickness of 18 μm was obtained in the same manner as in Example 10 except that the change was made. At this time, the ratio (stretch ratio) of the traveling speed of the film on the winding roll to the traveling speed of the film on the metal roll is 1.8 times.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Example 11]
The aqueous PVA solution prepared in Example 2 was cast and dried on a metal roll in the same manner as in Example 1 to form a film having a thickness of 29 μm. While this film was stretched 1.6 times in the longitudinal direction of the film (rotating direction of the metal roll), it was fixed to the metal frame with a clip, and was subjected to heat treatment at 120 ° C. for 2 minutes in a hot air dryer. . Therefore, the draw ratio of the film in the length direction in the seed packaging film is 1.6 times. The thickness of the obtained heat-treated PVA film was 18 μm.
Using this PVA film, after producing a seed packaging film in the same manner as in Example 1, the dissolution time when immersed in water at 5 ° C. according to the method described above and the length direction when floating on the water surface at 20 ° C. The number of seeds germinated was examined in the same manner as in Example 1. The results are shown in Table 1.

[Control Example 2]
In Comparative Example 3, the number of germinated seeds was examined in the same manner as in Comparative Example 3 except that corn seeds (Takii Seed Co., Ltd .: Sweetcorn Canberra 90) were used instead of turnip seeds. The results are shown in Table 1.

  According to the present invention, since a seed package showing a good germination rate can be obtained even for seeds with weak germination ability, it is possible to eliminate the waste of seeds and the trouble of thinning, and the number of seeds to be sown or seeded. It is possible to prevent inefficient operation of farmland due to seeds not germinating, and as a result, it is possible to reduce the production cost of crops such as vegetables.

Claims (5)

  A seed package comprising a seed wrapped with a long polyvinyl alcohol polymer film, wherein the polyvinyl alcohol polymer film has a dissolution time of 5 to 30 seconds when immersed in water at 5 ° C, A seed package having a shrinkage ratio in the length direction of 15% or less when floated on a water surface at 20 ° C.   The polyvinyl alcohol polymer film contains 1 to 30 parts by mass of at least one of starch (B) and inorganic powder (C) with respect to 100 parts by mass of the polyvinyl alcohol polymer (A). The seed package according to 1.   The seed package according to claim 2, wherein the inorganic powder (C) is at least one selected from the group consisting of talc, silica, titanium dioxide, and calcium carbonate.   The seed package according to any one of claims 1 to 3, wherein the seed is a seed of a cruciferous plant.   A long polyvinyl alcohol-based polymer film for wrapping seeds into a seed package, having a dissolution time of 5 to 30 seconds when immersed in water at 5 ° C. and floating on the water surface at 20 ° C. A polyvinyl alcohol polymer film having a shrinkage ratio in the length direction of 15% or less.