JP6415362B2 - Water-soluble multilayer film and vegetation sheet using the same - Google Patents

Description

  The present invention relates to a water-soluble multilayer film and a vegetation sheet using the same.

  The vegetation sheet is a laminate in which a plant (one or more of stems, roots, seeds, seeds after germination, etc.) is sandwiched between two water-soluble resin films. A water-soluble resin film dissolves by spreading on the ground and spraying water, and is an agricultural sheet suitable for uses such as germination and growth of plants in a desired planting site.

  Conventionally, a lawn seed sheet obtained using a biodegradable sheet and a water-soluble film is known as a kind of vegetation sheet.

  For example, Patent Document 1 discloses that in a method for producing a turf seed sheet (11) in which turf seed (2) is sandwiched between a biodegradable sheet (1) and a water-soluble film (3), the biodegradable sheet A method for producing a turf seed sheet, characterized in that the water-soluble film is bonded by pressing after spraying turf seeds thereon and then spraying the turf seeds on the turf seeds "is disclosed. Here, examples of the biodegradable sheet include natural fibers, cellulose-based artificial fibers, and synthetic fibers (paragraph [0019]). Examples of the water-soluble film include cellulose derivatives such as polyvinyl alcohol and carboxymethyl cellulose, Examples include vinyl acetate, starch and the like (paragraph [0021]).

  Patent Document 2 discloses a seed tape as a kind of vegetation sheet. Particularly, as a polyvinyl alcohol film for a seed tape, “polyvinyl alcohol having a saponification degree of 65 mol% or more and less than 75 mol% (A ) And a polyvinyl alcohol (B) having a saponification degree of 75 mol% or more, and a seed characterized by a difference in saponification degree between the polyvinyl alcohol (A) and the polyvinyl alcohol (B) of 3 mol% or more. Polyvinyl alcohol film for tapes "is disclosed. Here, the seed tape is obtained by placing seeds on the water-soluble film at regular intervals, and then twisting the water-soluble film so that the seed is enclosed in the water-soluble film (paragraph [0027]). The sheet tape is buried in the soil, and the tape substrate is dissolved (disintegrated) by moisture in the soil, so that the seeds enclosed (clamped) in the tape are exposed in the soil and grow (germination). ) (Paragraph [0028]).

JP 2000-300073 A Japanese Patent No. 4705255

  However, the conventional vegetation sheet (including the seed tape) has a problem that the base material is easily broken when water is sprayed onto the polyvinyl alcohol base material before fixing the contents such as seeds. For this reason, the contents may not be fixed, such as seeds falling from the edges due to vibration when transporting vegetation sheets with seeds sandwiched, or seeds falling when the vegetation sheet is spread during construction. It has been pointed out that it tends to be sufficient.

  Therefore, it is desired to develop a vegetation sheet in which the contents such as seeds are well fixed and a water-soluble resin film suitable for the production of such a vegetation sheet.

  An object of this invention is to provide the vegetation sheet | seat with favorable fixability of contents, such as a seed, and the water-soluble resin film (water-soluble multilayer film) suitable for manufacture of this vegetation sheet | seat.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the outermost layers 1 and 2 having a specific water-soluble time and the water-solubility of three or more layers having the layer 3 having a specific water-soluble time and thickness condition. When producing a vegetation sheet by a multilayer film, it discovered that the said objective can be achieved and came to complete this invention.

That is, this invention relates to the following water-soluble multilayer film and a vegetation sheet using the same.
1. a water-soluble multilayer film of three or more layers having a layer 3 between an outermost layer 1 and an outermost layer 2,
(1) The outermost layer 1 and the outermost layer 2 have a time (water solubility time) until complete dissolution measured by subjecting to water solubility test A is less than 90 seconds,
(2) In the layer 3, the water-soluble time is 90 seconds to 600 seconds ,
(3) The layer 3 is the 20μm or less in thickness, and state, and are percentage or more and 50% or less 10% occupied by the layer 3 of the total layer thickness of the water-soluble multi-layer film,
(4) The outermost layer 1 and the outermost layer 2 are made of a polyvinyl alcohol-based resin having a saponification degree of 85 mol% or more and less than 90 mol%, and
(5) The layer 3, ing from saponification degree 90 mol% to 100 mol% of a polyvinyl alcohol-based resin,
A water-soluble multilayer film characterized by that.
2. The water-soluble multilayer film according to item 1, wherein a difference between the water-soluble time of the outermost layer 1 and the outermost layer 2 and the water-soluble time of the layer 3 is 20 seconds or more.
3. A vegetation sheet comprising a plant sandwiched between two resin films, wherein one or both of the two resin films are the water-soluble multilayer film according to item 1 or 2 .
4. Both of the two resin films are the water-soluble multilayer film according to the above item 1 or 2, and the two water-soluble multilayer films facing each other are part of a region not sandwiching the plant Item 4. The vegetation sheet according to Item 3 , which is bonded in all.
5. The vegetation sheet according to item 3 or 4 , wherein the plant is at least one selected from the group consisting of stems, roots, seeds and seeds after germination.
6. The vegetation sheet according to any one of Items 3 to 5 , wherein the plant is turfgrass.

  The water-soluble multilayer film of the present invention has the outermost layer 1, the outermost layer 2 and the layer 3 that have different time to complete dissolution (water-soluble time) measured by subjecting to the water-soluble test A. It is useful as a base material for producing a vegetation sheet by having a layer configuration of three or more layers having the layer 3 between the outer layer 2 and the outer layer 2. When producing a vegetation sheet by sandwiching a plant between two resin films, one or both of the two resin films are the water-soluble multilayer film of the present invention, so that the plant (contents) in the vegetation film is Falling is suppressed. In particular, when both of the two resin films are the water-soluble multilayer film of the present invention, the hardness of the entire vegetation film is reduced in addition to the effect of suppressing the fall of the plant (contents). Therefore, when the vegetation sheet is developed on a desired planting site, the vegetation sheet easily follows the shape of the planting site, and good adhesion between the vegetation sheet and the planting site is obtained.

(A) It is a typical perspective view of the test apparatus of the water solubility test A. FIG. (B) is a top view of the beaker and schematically shows the relationship between the slide mount and the water flow. It is a top view top view which shows an example of the vegetation sheet which taught the plant (seed). It is side surface sectional drawing which shows an example of the vegetation sheet which taught the plant (seed). It is a top view top view which shows an example of the vegetation sheet which taught the plant (turf grass). It is side surface sectional drawing which shows an example of the vegetation sheet which taught the plant (turf grass).

  Hereinafter, the water-soluble multilayer film and vegetation sheet of the present invention will be described in detail.

Water-soluble multilayer film The water-soluble multilayer film of the present invention is a water-soluble multilayer film of three or more layers having a layer 3 between the outermost layer 1 and the outermost layer 2,
(1) The outermost layer 1 and the outermost layer 2 have a time (water solubility time) until complete dissolution measured by subjecting to water solubility test A is less than 90 seconds,
(2) The layer 3 has the water-soluble time of 90 seconds or more,
(3) The layer 3 has a thickness of 20 μm or less, and the proportion of the layer 3 in the total thickness of the water-soluble multilayer film is 10% or more and 50% or less.
It is characterized by that.

  The water-soluble multilayer film of the present invention having the above characteristics has the outermost layer 1 and the outermost layer 2 and the layer 3 having different time to complete dissolution (water-soluble time) measured by subjecting to the water solubility test A. The layer structure of three or more layers having the layer 3 between the outer layer 1 and the outermost layer 2 is useful as a base material for producing a vegetation sheet. When producing a vegetation sheet by sandwiching a plant between two resin films, one or both of the two resin films are the water-soluble multilayer film of the present invention, so that the plant (contents) in the vegetation film is Falling is suppressed. In particular, when both of the two resin films are the water-soluble multilayer film of the present invention, the hardness of the entire vegetation film is reduced in addition to the effect of suppressing the fall of the plant (contents). Therefore, when the vegetation sheet is developed on a desired planting site, the vegetation sheet easily follows the shape of the planting site, and good adhesion between the vegetation sheet and the planting site is obtained.

In addition, the water solubility test A in this specification is a test method defined as follows.
(B) As shown in Fig. 1, put 800ml of ultrapure water at 25 ° C and 40mm x φ8mm rotator into a 1000ml beaker (HARIO beaker manufactured by Shibata Science Co., Ltd., outer diameter 110mm, height 151mm) and rotate the rotor. The rotation speed is set so that the lower end of the spiral of ultra pure water is positioned in the 600 ml line (the condition is approximately 450 rpm).
(B) Attach a 60 μm thick sample film (Layer 1, Layer 2, etc.) to a slide mount having a frame of 24 mm in length × 36 mm in width, and immerse it in a beaker so that the surface of the sample film is parallel to the water flow. The time until the sample film is completely dissolved (this time is referred to as “dissolution time”) is confirmed by visual observation and measured. In FIG. 1, (a) is a schematic perspective view of a test apparatus for water solubility test A, and (b) is a top view of the beaker, schematically showing the relationship between the slide mount and the water flow.

  In the water-soluble multilayer film of the present invention, the outermost layer 1 and the outermost layer 2 have a water solubility time of less than 90 seconds, and the layer 3 has a water solubility time of 90 seconds or more. The water-soluble time of the outermost layer 1 and the outermost layer 2 is preferably 85 seconds or less, and more preferably 20 to 80 seconds. The water-soluble time of the layer 3 is preferably 110 seconds or more, and more preferably 300 to 600 seconds. Further, the difference between the water time of the outermost layer 1 and the outermost layer 2 and the water time of the layer 3 is preferably 20 seconds or more, and more preferably 30 seconds or more.

  When a plant (content) is sandwiched between two resin films to produce a vegetation sheet, the water-soluble multilayer film of the present invention is used as one or both of the two resin films. When the outermost layer 1 or 2 having a short water-soluble time is in contact with the plant, the plant is sufficiently fixed, and when the layer 3 having a long water-soluble time is present between the outermost layers 1 and 2, the plant is fixed (particularly It is possible to suppress vegetation sheet breakage and subsequent plant fall during water spraying. Therefore, when the vegetation sheet is transported or when the vegetation sheet is expanded during construction, the fall of the plant is suppressed. In addition, when both of the two resin films are the water-soluble multilayer film of the present invention, the two water-soluble multilayer films are bonded to each other in a part or all of the region not holding the plant. As a result, the plant is more sufficiently fixed, and the hardness of the entire vegetation film is relaxed. When the vegetation sheet is developed on the desired planting area, the vegetation sheet becomes the shape of the planting area. It is easy to follow and good adhesion between the vegetation sheet and the planting area is obtained.

  Thus, layer 3 with a water-soluble time of 90 seconds or more is effective to prevent the vegetation sheet from being torn when the plant is fixed, and outermost layers 1 and 2 with a water-soluble time of less than 90 seconds produce a vegetation sheet. This is effective for securing the plant when it is done. In addition to the multilayer film having three or more layers having the layer 3 between the outermost layers 1 and 2, the effect is that the thickness of the layer 3 is 20 μm or less, and the total thickness of the water-soluble multilayer film is Of these, the ratio of the layer 3 is 10% or more and 50% or less. Details about the thickness of each layer are shown below.

  The thickness of the outermost layers 1 and 2 is not limited as long as the thickness ratio of the layer 3 is satisfied, but the outermost layers 1 and 2 are each preferably 5 to 65 μm, and more preferably 10 to 50 μm.

  In addition, the total thickness (total thickness) of the water-soluble multilayer film is preferably 0.015 to 0.150 mm, and more preferably 0.020 to 0.080 mm. Of the total thickness, the thickness of the layer 3 is 20 μm or less (preferably 5 to 15 μm), and the proportion of the layer 3 is in the range of 10% to 50% (preferably 15 to 40%) Within the range. When the proportion of layer 3 is within the range of 10% or more and 50% or less, the vegetation sheet can be prevented from being broken when the plant is sandwiched and fixed, and further, it has a good hardness that easily follows the shape of the planting land. It can be adjusted. Especially when the proportion of layer 3 exceeds 50%, the hardness of the vegetation sheet increases, and the ability to follow the shape of the vegetation sheet decreases and there is a gap between the vegetation sheet and the vegetation sheet. (Floating) may occur.

  The resins (materials) constituting the outermost layers 1 and 2 and the layer 3 are not limited as long as they are water-soluble and each have a predetermined water-water requirement. For example, examples of the resin include polyvinyl alcohol resins (PVA resins), cellulose derivatives, starch, and the like. The PVA resin may be either PVA or modified PVA, but PVA is preferred. In the case of using a PVA-based resin, the water solubility time can be adjusted by adjusting the degree of saponification, the copolymerization ratio or modification amount of the unsaturated monomer, the molecular weight, the layer thickness, etc. When starch is used, the water solubility time can be adjusted by adjusting the amount of modification, molecular weight, layer thickness and the like.

  As the PVA resin, a resin obtained by homopolymerizing vinyl acetate and further saponifying it can be used. As the modified PVA, a saponified polymer of vinyl acetate and another unsaturated monomer or a post-modified PVA can be used. The amount of modification when PVA is post-modified is not particularly limited, but is preferably 10 mol% or less, more preferably 7 mol% or less, and most preferably 5 mol% or less.

  Examples of the unsaturated monomer include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene; acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itacone Unsaturated acids such as acids, or salts thereof, or mono- or dialkyl esters thereof; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, etc. Olefin sulfonic acid or salt thereof; alkyl vinyl ethers; N-acrylamidomethyltrimethylammonium chloride; allyltrimethylammonium chloride; dimethylallyl vinyl ketone; N-vinyl pyrrolidone; vinyl chloride; Polyoxyalkylene (meth) allyl ethers such as polyoxyethylene (meth) allyl ether and polyoxypropylene (meth) allyl ether; polyoxyalkylenes such as polyoxyethylene (meth) acrylate and polyoxypropylene (meth) acrylate (Meth) acrylate; polyoxyalkylene (meth) acrylamide such as polyoxyethylene (meth) acrylamide and polyoxypropylene (meth) acrylamide; polyoxyethylene (1- (meth) acrylamide-1,1-dimethylpropyl) ester; Polyoxyethylene vinyl ether; polyoxypropylene vinyl ether; polyoxyethylene allylamine; polyoxypropylene allylamine; polyoxyethylene vinylamine; polyoxypropylene vinyl Amine and the like. The copolymerization ratio of these unsaturated monomers in the PVA-based resin is not limited, depending on the water-soluble time of the outermost layers 1 and 2 and the layer 3 and the characteristics of the water-soluble multilayer film and vegetation sheet as the final product. It can be set appropriately.

  Examples of the method for post-modifying PVA include a method in which PVA is esterified with acetoacetate, acetalized, urethanized, etherified, esterified with phosphoric acid, or oxyalkylenated.

  As the PVA resin, it is preferable to use a PVA resin having a 1,2-diol bond in the side chain. The PVA resin having a 1,2-diol bond in the side chain is, for example, (a) a method of saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene; Of saponifying and decarboxylating a copolymer of ethylene and vinyl ethylene carbonate, (c) saponifying and deketalizing a copolymer of vinyl acetate and 2,2-dialkyl-4-vinyl-1,3-dioxolane And (d) a method of saponifying a copolymer of vinyl acetate and glycerin monoallyl ether.

  Regarding the saponification degree when using a PVA resin, the saponification degree is preferably 90 mol% or more and 100 mol% or less, and more preferably 92 to 97 mol% when used as the layer 3. When used as the outermost layers 1 and 2, the saponification degree is preferably 85 mol% or more and less than 90 mol%, more preferably 87 to 89 mol%. By adjusting the degree of saponification of the PVA resin used for the outermost layers 1 and 2 and the layer 3 to the above range, the characteristics of each water-soluble time described above are obtained, and the effect of suppressing the vegetation sheet from being broken by the layer 3, It leads to plant fixation effect by outermost layers 1 and 2. Moreover, the water-soluble time can also be adjusted by adjusting the copolymerization ratio or modification amount of the unsaturated monomer in the PVA resin. The value of the saponification degree in this specification means a value measured in accordance with JIS K6726. When a plurality of PVA resins having different saponification degrees are mixed, the saponification degree after mixing is determined. It is a measured value.

  You may mix | blend a plasticizer with PVA-type resin as needed. When blended, 1 to 8 parts by weight is preferable with respect to 100 parts by weight of the PVA resin. If the plasticizer content is less than 1 part by weight or more than 8 parts by weight, film formation may be difficult depending on the production method.

  Each of the outermost layers 1 and 2 and the layer 3 may be blended with one or two or more of an antioxidant, a metal deactivator and the like as necessary. A well-known additive can be used for the said additive, and a compounding quantity can be suitably adjusted in the range which does not impair the effect of this invention.

  When laminating the outermost layers 1 and 2, and the layer 3, the method of laminating by coextrusion of the resin composition for forming each layer, the method of laminating by extrusion lamination, or the outermost layers 1 and 2, and the layers A method of bonding 3 using a water-soluble adhesive (such as a PVA adhesive) can be used.

  Between the outermost layers 1 and 2, in addition to the layer 3, another layer (auxiliary layer) can be interposed as needed as long as the effects of the present invention are not impaired. As an auxiliary | assistant layer, the adhesive bond layer etc. which improve the interlayer intensity | strength of each layer are mentioned, for example. Further, as long as the outermost layers 1 and 2 are respectively positioned on the outermost surface of the water-soluble multilayer film, an intermediate layer made of the same resin as the outermost layers 1 and 2 is further interposed between the outermost layers 1 and 2. Also good. For example, the outermost layer 1 / intermediate layer / layer 3 / outermost layer 2 (“/” indicates an interlayer, and an adhesive layer may be further provided between each layer). It is good. The thickness of the auxiliary layer can be appropriately adjusted in relation to the total layer thickness described above.

  If necessary, the water-soluble multilayer film of the present invention may be formed with an embossed pattern on one side or both sides using a known technique. By embossing the embossed pattern, i) the effect of improving the blocking resistance when the water-soluble multilayer film is wound up and stored in a roll, ii) the process of sandwiching the plant when producing the vegetation sheet described later The effect which improves the workability at the time of using for a machine, the effect which improves the deaeration at the time of deaerating the excess air in a vegetation sheet after pinching a plant, etc. are show | played.

Vegetation Sheet The water-soluble multilayer film of the present invention is useful as a substrate for producing a vegetation sheet. That is, when a vegetation sheet is produced by sandwiching a plant between two resin films, one or both of the two resin films can be used as the water-soluble multilayer film of the present invention. When one of the two resin films is the water-soluble multilayer film of the present invention, the resin and thickness of the remaining resin film are not particularly limited as long as they are water-soluble resin films, depending on the type of vegetation sheet. It can be set appropriately. In particular, when both of the two resin films are the water-soluble multilayer film of the present invention, the two water-soluble multilayer films facing each other are part or all (preferably substantially not) of the region not holding the plant. In general).

  The above vegetation sheet is a laminate in which a plant (one or more of stems, roots, seeds, seeds after germination, etc.) is sandwiched between two resin films, and the vegetation sheet is developed on a desired planting site. Then, by spraying water, the water-soluble resin film dissolves, and it is an agricultural sheet suitable for applications in which plants are germinated and grown on a desired planting site.

  The above-mentioned plants are not limited to plants that have grown to some extent and have all the leaves, stems, and roots, but as long as they root and settle in the soil, branches, leaves, stems or roots collected from the grown plants In addition, seeds or seeds after germination may be used. Among these, at least one of stems, roots, seeds, and seeds after germination is preferable in that they are easily rooted and settled in the soil, and two or more of these can be used in combination.

  The kind of plant is not particularly limited, and may be a known plant that is widely cultivated in the fields of gardening, landscaping, and agriculture. For example, turfgrass, flowers, grass, vegetables and the like can be mentioned. Of these, turfgrass is preferred.

  When the plant is turfgrass, it is preferable that the turfgrass is in a state in which the entanglement of leaves, stems and roots is loosened and decomposed. By sandwiching turfgrass with a water-soluble resin film in a disassembled state, the volume can be made less bulky compared to a rectangular sheet-like lawn, and transport efficiency can also be improved.

  The plant is preferably dispersed and sandwiched between two water-soluble resin films. By dispersing and sandwiching the plant between two water-soluble resin films, the volume of the plant can be made less bulky, and the transport efficiency can be further improved. Moreover, when a plant is equally arrange | positioned on the surface of a water-soluble resin film, when planting a plant, it can plant in a wide range efficiently. In particular, if the plant is turfgrass, the roots will come out after planting and the density will increase naturally, so by dispersing and planting the turfgrass over a wide area, the soil where the turfgrass was planted at an early stage is converted to lawn. can do.

  The plant is preferably free of soil. Plants can be transported in a lightweight and volumeless state, and contamination of the transport facility with soil is suppressed. The method for removing the soil is not particularly limited, and a conventionally known method can be used. For example, there is a method of dropping the soil by hitting the root of a plant holding the soil, or a method of easily washing the soil and dropping the soil. The soil may be removed to such an extent that the soil unnecessary for transportation and storage is dropped as described above. It is preferable to remove the soil so that the soil adheres to the roots to such an extent that the state of the plant can be kept good.

  The water-soluble resin film of the vegetation sheet of the present invention is dissolved by moisture. Therefore, when a plant purchaser plants a plant, if the vegetation sheet is laid on the soil, the vegetation sheet is dissolved by moisture in the soil, and the plant can be planted on the soil. Although the soil has been removed from the plant, the plant settles in the soil by the dissolved vegetation sheet and the root of the plant overhangs into the soil over time, making it possible to plant the plant easily.

  Moreover, since the vegetation sheet of the present invention that dissolves by moisture as described above also has water content, it impregnates moisture in the air, suppresses drying of the plant in the vegetation sheet, and improves the state of the plant. Can keep.

  The method for sandwiching the plant between the two water-soluble resin films is not particularly limited as long as the plant can hold the state sandwiched between the two water-soluble resin films. For example, a method of winding a roll while spraying an appropriate amount of water on each of two water-soluble resin films and sandwiching the plants and joining the water-soluble resin films to such an extent that the state of sandwiching the plants can be maintained. It is done. When spraying water, an appropriate amount of water is sprayed so that the layer in contact with the plant is not completely dissolved.

  FIG. 2 is a top plan view of a vegetation sheet in which a plant (seed) is sandwiched using the water-soluble multilayer sheet of the present invention as two resin films, and FIG. 3 is a side sectional view. In FIG. 2 and FIG. 3, the vegetation sheet 6 sandwiching the plant has the plant 7 (seed) sandwiched between the two water-soluble multilayer films 81 and 82, and the two water-soluble multilayer films. 81 and 82 are joined in part or all (preferably substantially all) of a region where no plant is sandwiched. In order to adjust the bonding area, for example, it is possible to adjust the amount of water to be sprayed, to adjust the pressure when pressing the vegetation sheet after holding the plant, or to adjust the heat sealing conditions. By sandwiching the plant by such a method, it is possible to suppress the protrusion or fall of the plant being transported from the vegetation sheet. 4 and 5 are illustrations when the plant is changed from seed to turfgrass.

  The method for joining the two water-soluble resin films is not particularly limited, and examples thereof include a method such as heat sealing by heating in addition to the above-described method of spraying an appropriate amount of water. Moreover, you may join by the method of apply | coating or dripping a small amount of water to the desired location to join. Furthermore, in the above-described bonding method, a PVA aqueous solution may be used instead of water.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Examples 1-3 and Comparative Examples 1-5
A three-layer water-soluble multilayer film was prepared by the composition and configuration of outermost layers 1 and 2 and layer 3 shown in Tables 1 and 2 (Comparative Examples 1 and 2 produced a single-layer film of Layer 3) ). Specifically, the resin composition forming each layer was introduced into a feed block, and extruded into a 60 μm water-soluble multilayer film by a T-die extrusion method.

[In the table, “Selvol” indicates the brand name of PVA resin made by Sekisui Specialty Chemicals America.]

Test example 1
Each film obtained in Examples and Comparative Examples was evaluated for the presence or absence of perforations during watering, plant fixation during vegetation sheet production, and adhesion to the ground.

Evaluation methods and evaluation criteria are as follows.
≪Presence / absence of holes when watering≫
Water was sprayed on the surface of each film, and the presence or absence of holes in each film after being allowed to stand for 2 minutes was confirmed by visual observation. The amount of water sprayed was 2 blows using a 500cc handy sprayer.

Evaluation was as follows.
○: Generation of holes is not recognized, ×: Generation of holes is recognized

≪Evaluation of plant (content) fixation≫
Cut each film into a length of 150 mm × width 100 mm, spray water on the surface of the outermost layer 1 or 2 of the two films with water spray, and then sandwich 0.4 g of turf seeds (“Western turf” manufactured by Atalia Farm) After placing a weight (700 g) and curing in an environment of 23 ° C x 50% RH for 2 hours, measure the angle at which the seeds of turf start to move using a tumble angle measuring instrument (manufactured by Toyo Seiki Seisakusho). Judged by criteria. The two films were laminated so that the layers 2 were joined together.

  Table 3 shows the measured values of the sliding angle.

The plant fixation evaluation was as follows.
○: 50 ° or more, ×: less than 50 °

≪Evaluation of adhesion to the ground≫
Cut each film into a length of 150 mm × width 100 mm, spray water on the surface of the outermost layer 1 or 2 of the two films with water spray, and then sandwich 0.4 g of turf seeds (“Western turf” manufactured by Atalia Farm) The sample was placed on black soil, sprayed with a watering can, and the adhesion between each film and the black soil after standing for 5 minutes was confirmed by visual observation. The amount of water sprinkled was about 0.6 ml / cm ² using a watering can.

Evaluation was as follows.
○: Floating from the ground is less than 10%, ×: Floating from the ground is 10% or more

1. Sample film for water solubility test A
2. Slide mount
3. 1000ml beaker (HARIO beaker manufactured by Shibata Science Co., Ltd., outer diameter 110mm, height 151mm)
4. 40mm × φ8mm rotor
5. Magnetic stirrer
6. Vegetation sheet
7. Contents (plant)
81. Water-soluble multilayer film (the surface that contacts the inner plant is the outermost layer 1 or 2)
82. Water-soluble multilayer film (the surface that contacts the inner plant is the outermost layer 1 or 2)

Claims (6)

A water-soluble multilayer film of three or more layers having a layer 3 between the outermost layer 1 and the outermost layer 2,
(1) The outermost layer 1 and the outermost layer 2 have a time (water solubility time) until complete dissolution measured by subjecting to water solubility test A is less than 90 seconds,
(2) In the layer 3, the water-soluble time is 90 seconds to 600 seconds ,
(3) The layer 3 is the 20μm or less in thickness, and state, and are percentage or more and 50% or less 10% occupied by the layer 3 of the total layer thickness of the water-soluble multi-layer film,
(4) The outermost layer 1 and the outermost layer 2 are made of a polyvinyl alcohol-based resin having a saponification degree of 85 mol% or more and less than 90 mol%, and
(5) The layer 3, ing from saponification degree 90 mol% to 100 mol% of a polyvinyl alcohol-based resin,
A water-soluble multilayer film characterized by that.   2. The water-soluble multilayer film according to claim 1, wherein a difference between the water-soluble time of the outermost layer 1 and the outermost layer 2 and the water-soluble time of the layer 3 is 20 seconds or more. 3. A vegetation sheet obtained by sandwiching a plant between two resin films, wherein one or both of the two resin films is the water-soluble multilayer film according to claim 1 or 2 . The two resin films are both water-soluble multilayer films according to claim 1 or 2, and the two water-soluble multilayer films facing each other are part or all of a region not sandwiching the plant. The vegetation sheet according to claim 3 , which is bonded in 5. The vegetation sheet according to claim 3 , wherein the plant is at least one selected from the group consisting of stems, roots, seeds and seeds after germination. The vegetation sheet according to any one of claims 3 to 5 , wherein the plant is turfgrass.