JP2016064587A - Water soluble multilayer film and vegetation sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water soluble multilayer film excellent in water solubility as well as blocking resistance during moisture absorption.SOLUTION: There is provided a water soluble multilayer film having an A layer and a B layer on each outermost surface, where (1) the A layer contains an antiblocking agent having the melting point of 230°C or less of 0.5 pts.wt, based on 100 pts.wt. of a water soluble resin and (2) the B layer contains no or less than 0.5 pts.wt. of the antiblocking agent having the melting point of 230°C or less based on 100 pts.wt. of a water soluble resin.SELECTED DRAWING: None

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, germinated seeds, etc.) is sandwiched between two water-soluble resin films, and a desired vegetation sheet is planted. 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.

  Water-soluble films mainly composed of a water-soluble resin such as polyvinyl alcohol resin are used in various fields such as printing on curved surfaces by a hydraulic transfer printing method, detergents, and individual packaging of drugs.

  However, due to the nature of water-soluble films, moisture absorption and dissolution due to moisture in the air is inevitable, and problems such as surface stickiness, film self-adhesion, and adhesion to other packaging materials It is known that (mainly the problem of blocking) occurs.

  In order to solve these problems, Patent Document 1 proposes a method of applying and drying a hydrophobic synthetic resin emulsion on the surface. Patent Document 2 proposes a method in which a cationic surfactant which is a quaternary ammonium salt compound such as alkylpolyoxyethylene-added dimethylammonium chloride is contained in a polyvinyl alcohol resin.

  However, the method described in Patent Document 1 requires a step of applying an emulsion and drying after forming a water-soluble film. In addition, when an emulsion is applied, there is a concern that the water-soluble film is softened or deformed. When an emulsion is applied using an oily solvent as a solvent, the environmental load becomes a problem. In addition, the method described in Patent Document 2 is that the addition of a surfactant makes the front and back of a water-soluble film homogeneous and the purpose of preventing blocking can be achieved, but when adding a surfactant to the extent that blocking due to moisture absorption can be prevented, On the other hand, there is a concern that water solubility may be reduced by hydrophobization.

  As a method other than the above, it has been proposed to prevent blocking by substantially reducing the contact area by providing embossing or the like to the water-soluble film, not the composition of the water-soluble film itself. However. This method has a problem that the embossing is easily deformed when the pressure is applied after the water-soluble film absorbs moisture, and the effect of preventing blocking is impaired.

Japanese Patent Laid-Open No. 47-1000018 Japanese Patent No. 20603341 (Japanese Patent Laid-Open No. 5-163369)

  An object of this invention is to provide the water-soluble multilayer film which was excellent in water solubility, and was excellent also in the blocking resistance at the time of moisture absorption.

  As a result of intensive studies to achieve the above object, the present invention finds that the above object can be achieved by a water-soluble multilayer film having a specific A layer and B layer on the outermost surface, and completes the present invention. It came to.

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 having an A layer and a B layer on the outermost surface,
(1) The layer A contains 0.5 parts by weight or more of an antiblocking agent having a melting point of 230 ° C. or less with respect to 100 parts by weight of the water-soluble resin.
(2) The B layer does not contain an antiblocking agent having a melting point of 230 ° C. or lower or contains less than 0.5 parts by weight with respect to 100 parts by weight of the water-soluble resin.
A water-soluble multilayer film characterized by that.
2. The water-soluble multilayer film according to Item 1, wherein the water-soluble resin contains a polyvinyl alcohol-based resin.
3. Item 3. The water-soluble multilayer film according to Item 2, wherein the polyvinyl alcohol resin contained in the A layer has a saponification degree of 92 mol% or more.
4). Item 4. The water-soluble multilayer film according to Item 2 or 3, wherein the polyvinyl alcohol resin contained in the B layer has a saponification degree of less than 92 mol%.
5. Item 5. The water-soluble multilayer film according to any one of Items 1 to 4, wherein the antiblocking agent is a metal soap.
6). A vegetation sheet comprising the water-soluble multilayer film according to any one of Items 1 to 5.
7. A vegetation sheet in which a plant is sandwiched between two resin films, each of the two resin films being the water-soluble multilayer film according to any one of Items 1 to 5, Each of the B layers of the water-soluble multilayer film is in contact with the plant, and the two water-soluble multilayer films facing each other are joined in part or all of a region not sandwiching the plant, The vegetation sheet according to Item 6 above.
8). The vegetation sheet according to Item 7, wherein the plant is at least one selected from the group consisting of stems, roots, seeds and seeds after germination.
9. The vegetation sheet according to Item 7 or 8, wherein the plant is turfgrass.

  The water-soluble multilayer film of the present invention has a specific A layer and B layer on the outermost surface, so that it has excellent water solubility and anti-blocking property when absorbing moisture. Such a water-soluble multilayer film is useful as a material for producing, for example, a vegetation film in which a plant is sandwiched between two water-soluble multilayer films.

(A) It is a typical perspective view of the test apparatus of the water-soluble test A. (B) is a top view of a beaker and schematically shows the relationship between a slide mount and a water flow. It is a top view top view which shows an example of the vegetation sheet which clamped the plant (seed). It is side surface sectional drawing which shows an example of the vegetation sheet which clamped the plant (seed). It is a top view top view which shows an example of the vegetation sheet | seat which pinched | interposed the plant (turf grass). It is side view sectional drawing which shows an example of the vegetation sheet which pinched | interposed 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 has an A layer and a B layer on the outermost surface (opposite surface),
(1) The layer A contains 0.5 parts by weight or more of an antiblocking agent having a melting point of 230 ° C. or less with respect to 100 parts by weight of the water-soluble resin.
(2) The B layer is characterized by not containing an antiblocking agent having a melting point of 230 ° C. or less or less than 0.5 parts by weight with respect to 100 parts by weight of the water-soluble resin.

  The water-soluble multilayer film of the present invention having the above characteristics is excellent in water solubility and anti-blocking property during moisture absorption by having the specific A layer and B layer on the outermost surface. Such a water-soluble multilayer film is useful as a material for producing, for example, a vegetation film in which a plant is sandwiched between two water-soluble multilayer films. The excellent blocking resistance of the present invention is not only when the water-soluble multilayer film is stored in a roll form, but also when the two water-soluble multilayer films are combined to form a vegetation sheet and stored as a vegetation sheet in a roll form. It is demonstrated in any of these.

  The water-soluble multilayer film of the present invention has an A layer and a B layer on the outermost surface, respectively, and the A layer has a melting point of 230 ° C. or lower than the B layer (hereinafter simply referred to as “anti-blocking agent”). A lot). That is, when comparing the A layer and the B layer, the A layer is superior in blocking resistance.

  The water-soluble multilayer film of the present invention having such an A layer and a B layer on the outermost surface is the B layer of each of the two water-soluble multilayer films when a vegetation sheet is produced by sandwiching a plant (contents). Are laminated so that they come into contact with the plant. At this time, each B layer is in contact with the plant, and the two water-soluble multilayer films facing each other are joined together in part or all of the region where the plant is not sandwiched, thereby sufficiently fixing the plant. . Therefore, when the vegetation sheet is transported or when the vegetation sheet is spread during construction, the fall of the plant is suppressed. Moreover, since all the outermost surfaces of a vegetation sheet become A layer, even when the vegetation sheet is stored in a roll shape for a long time (at the time of moisture absorption), excellent blocking resistance is exhibited. That is, the A layer containing a large amount of an antiblocking agent is effective for expressing blocking resistance, and the B layer is effective for obtaining an effect of sufficiently fixing a plant when a vegetation sheet is produced. Such an effect can be obtained by forming a multilayer film having an A layer and a B layer on the outermost surface. In order to further enhance the effect of the B layer, it is preferable that the B layer has higher water solubility (shorter water time) than the A layer.

  The thicknesses of the A layer and the B layer are not limited, but the A layer is preferably 0.001 to 0.100 mm, and more preferably 0.005 to 0.050 mm. The B layer is preferably 0.001 to 0.120 mm, more preferably 0.005 to 0.060 mm. In addition, the total layer thickness (total thickness) of the water-soluble multilayer film is preferably 0.015 to 0.150 mm, more preferably 0.020 to 0.080 mm, and the total thickness of the water-soluble multilayer film is The proportion of the A layer is preferably in the range of 5 to 90% (particularly in the range of 20 to 70%). When the proportion of the A layer is within the range of 5 to 90%, the vegetation sheet can be prevented from being broken when the plant is sandwiched and fixed, and further, blocking resistance can be more reliably obtained.

  The material of the resin film which comprises A layer and B layer will not be limited if it is water-soluble. For example, the material of the resin film constituting the A layer and the B layer includes polyvinyl alcohol resin (PVA resin); polyacrylic acid and / or a derivative thereof; polyvinyl pyrrolidone; a cellulose derivative; starch and / or a derivative thereof; And the like. Among these materials, PVA-based resins are preferable in that they have an excellent balance between strength and water solubility as a film. As PVA-type resin, any of PVA and modified PVA may be sufficient.

  When the PVA-based resin is used, the degree of water solubility 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, and the like. When polyacrylic acid (or a derivative thereof), polyvinylpyrrolidone, cellulose derivative, or starch (or a derivative thereof) is used, the degree of water solubility is adjusted by adjusting the modification amount, molecular weight, layer thickness, and the like. be able to.

  As the PVA-based resin, those obtained by homopolymerizing vinyl acetate and further saponifying it can be used. Moreover, as said modified PVA, what saponified the polymer of vinyl acetate and another unsaturated monomer, and the thing which modified | denatured PVA can be used. The amount of modification when PVA is post-modified is not particularly limited, but is preferably 20 mol% or less, more preferably 10 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; polyoxyethylene (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, and is appropriately set according to the water-soluble time of the A layer and the B layer and the characteristics of the water-soluble multilayer film and the vegetation sheet as the final product. Can do.

  Examples of the method of post-modifying PVA include a method of converting PVA into acetoacetate, acetalization, urethanization, etherification, phosphate esterification, or oxyalkylene.

  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, or (b) vinyl acetate. Of saponifying and decarboxylating a copolymer of ethylene and vinylethylene 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.

  About the saponification degree when using PVA-type resin, when using as an A layer, 92 mol% or more is preferable, 92-99.5 mol% is more preferable, 92-96.5 mol% is more preferable. Most preferred. When used as the B layer, the saponification degree is preferably less than 92 mol%, more preferably 80 mol% or more and less than 92 mol%, and most preferably 85 to 91 mol%.

  By adjusting the degree of saponification of the PVA-based resin used for the A layer and the B layer to the above range, it is possible to achieve a water-soluble degree suitable for each layer, the expression of the blocking resistance of the A layer, the plant of the B layer It is easy to obtain the effect of sufficiently fixing. The degree of water solubility can also be adjusted by adjusting the copolymerization ratio or the amount of modification of the unsaturated monomer in the PVA resin. In addition, the value of the saponification degree in this specification means a value measured according to JIS K6726. When a plurality of PVA resins having different saponification degrees are mixed, the saponification degree after mixing is measured. It is the value.

  In the present specification, the water solubility of the water-soluble multilayer film obtained by combining the A layer, the B layer, and these layers can be set based on, for example, the water solubility time measured from the following water solubility test A. .

The water solubility test A in this specification is a test method defined as follows.
(B) As shown in FIG. 1, put 800 ml of ultrapure water at 25 ° C. and a rotor of 40 mm × φ8 mm in a 1000 ml beaker and rotate the rotor so that the lower end of the vortex of ultrapure water is positioned in the 600 ml line. Set the number (appropriate conditions at approximately 450 rpm).
(B) A sample film (A layer, B layer or water-soluble multilayer film) with a thickness of 50 μm is attached to a slide mount having a frame of length 24 mm × width 35 mm, and in a beaker so that the surface of the sample film is parallel to the water flow The time until the sample film is broken (this time is referred to as “water-soluble 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.

  The water-soluble time of the water-soluble multilayer film of the present invention is not limited and can be appropriately adjusted according to the specific application, but is preferably 30 seconds or less, more preferably 20 seconds or less, and most preferably 5 to 15 seconds.

  Regarding the viscosity in the case of using the PVA-based resin, the viscosity value of 4 wt% aqueous solution is preferably 4.5 cP or more, and more preferably 5.0 cP or more. When the viscosity value of the PVA-based resin is low, the strength of the A layer and / or the B layer may be insufficient or may be easily blocked. The upper limit of the viscosity value is not limited, but is about 35 cP. The 4 wt% aqueous solution viscosity value in the present specification is a value measured by preparing a 4 wt% aqueous solution of PVA resin and conforming to JIS K6726: 1994 3.11.1 (rotary viscometer method).

  In this invention, A layer contains 0.5 weight part or more of antiblocking agents whose melting | fusing point is 230 degrees C or less with respect to 100 weight part of water-soluble resin. Moreover, B layer does not contain the antiblocking agent whose melting | fusing point is 230 degrees C or less with respect to 100 weight part of water-soluble resins, or contains less than 0.5 weight part. The content in the A layer may be 0.5 parts by weight or more, preferably 1 part by weight or more, and more preferably 1.5 parts by weight or more.

  The upper limit of the amount depends on the type of antiblocking agent to be used, but if it exceeds 10 parts, there is a concern that the mechanical properties of the film itself will deteriorate and the water solubility will decrease due to hydrophobization. Further, for the purpose of facilitating melt molding, an anti-blocking agent may be added to the B layer in a range of less than 0.5 part with respect to 100 parts of PVA resin. If this range is exceeded, the surface of the layer B is also hydrophobic and the desired water solubility may not be obtained.

  In order to minimize the influence of the A layer on the water solubility and to effectively exhibit the blocking resistance, it is effective to segregate the antiblocking agent on the surface of the A layer. For this purpose, the melting point of the antiblocking agent contained in the A layer needs to be 230 ° C. or less, preferably 200 ° C. or less, and more preferably 165 ° C. or less. In addition, when the anti-blocking agent itself is melted in the distribution stage of the water-soluble multilayer film, the melting point of the anti-blocking agent itself may block the water-soluble multilayer film. Preferably, 60 degreeC or more is more preferable. Here, the melting point in this specification is a value measured by differential scanning calorimetry in accordance with JIS K7121.

  The anti-blocking agent is not particularly limited as long as it can withstand the processing temperature of a water-soluble resin (for example, the processing temperature of PVA is about 220 ° C.) and has a melting point of 230 ° C. or lower. , Hydrocarbons, fatty acids, higher alcohols, aliphatic amides, metal soaps, esters, and the like.

  More specifically, examples of the hydrocarbon type include liquid paraffin, paraffin wax, and synthetic polyethylene wax. Examples of the fatty acid type include stearic acid. Examples of higher alcohols include stearyl alcohol. Examples of the aliphatic amides include fatty acid amides such as stearic acid amide, oleic acid amide, and erucic acid amide, and alkylene fatty acid amides such as methylene bis stearic acid amide and ethylene bis stearic acid amide. Examples of metal soaps include metal stearates (lead stearate, zinc stearate, sodium stearate, magnesium stearate, potassium stearate, calcium stearate, lithium stearate, etc.). Examples of the ester group include stearic acid monoglyceride and stearyl stearate, which are fatty acid esters of alcohol. These antiblocking agents can be used alone or in admixture of two or more.

  Among these antiblocking agents, metal soap-based antiblocking agents are preferable from the viewpoint of achieving both water solubility and blocking resistance. Among the metal soap-based antiblocking agents, alkali metal stearate and alkaline earth metal stearate are preferable, and magnesium stearate is more preferable.

  You may mix | blend a plasticizer with water-soluble resin as needed. When mix | blending, 1-8 weight part is preferable with respect to 100 weight part of water-soluble 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.

  You may mix | blend 1 type (s) or 2 or more types, such as antioxidant and a metal deactivator, in each layer of A layer and B layer as needed. 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 A layer and the B layer, a method of laminating the resin composition for forming each layer by coextrusion, a method of laminating by extrusion laminating, or the A layer and the B layer are made of a water-soluble adhesive (PVA A method of bonding using a system adhesive or the like can be used.

  Another layer (auxiliary layer) can be interposed between the A layer and the B layer 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 A layer and B layer are mentioned, for example. Further, as long as the A layer and the B layer are respectively positioned on the outermost surface of the water-soluble multilayer film, an A layer and / or a B layer may be further interposed between the A layer and the B layer. For example, a layer configuration of three or more layers such as A layer / B layer / A layer / B layer (“/” indicates an interlayer, and an adhesive layer may be provided between each layer) 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 further improving the blocking resistance when the water-soluble multilayer film is wound and stored with a roll, ii) the plant is sandwiched when producing the vegetation sheet described later The effect which improves the workability at the time of using for a processing machine, iii) 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, a vegetation sheet is obtained by preparing two sheets of the water-soluble multilayer film of the present invention and forming a laminate so that each layer B of the two water-soluble multilayer films is in contact with and pinched with plants. Note that the two water-soluble multilayer films facing each other are joined in part or all (preferably substantially all) of a region where no plant is sandwiched.

  The vegetation sheet is a laminate in which a plant (one or more of stems, roots, seeds, germinated seeds, etc.) is sandwiched between two water-soluble multilayer films, and the vegetation sheet is a desired planting site. It is an agricultural sheet suitable for applications in which a water-soluble resin film is dissolved by spreading and spraying water and germinating, growing and the like in 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 terms of easy rooting and establishment 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 multilayer film in a decomposed state, the volume can be made less bulky than that of a rectangular sheet-like lawn, and transport efficiency can be improved.

  The plant is preferably dispersed and sandwiched between two water-soluble multilayer films. By dispersing and sandwiching the plant between two water-soluble multilayer films, the volume of the plant can be made less bulky and transport efficiency can be further improved. Moreover, when a plant is equally arrange | positioned on the surface of a water-soluble multilayer film, when planting a plant, it can plant efficiently in a wide range. 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 removal of the soil may be performed to such an extent that the soil unnecessary for transportation and storage is dropped as described above, or may be completely washed away. The adhesion state of the soil can be appropriately selected according to the intended transportation and storage conditions and transportation and storage method, in addition to the type and state of the plant.

  The water-soluble multilayer 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 watering or 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 multilayer films is not particularly limited as long as the plant can hold the state sandwiched between the two water-soluble multilayer films. For example, after spraying an appropriate amount of water to each B layer of two water-soluble multilayer films, the plants are sandwiched, and the water-soluble multilayer films are joined together so that the state in which the plants are sandwiched can be maintained, and wound with a roll. A method is mentioned. When spraying water, an appropriate amount of water that does not completely dissolve the layer B in contact with the plant is sprayed.

  FIG. 2 is a top plan view of a vegetation sheet sandwiching a plant (seed) by the above method, and FIG. 3 is a side sectional view. 2 and 3, the vegetation sheet 6 sandwiching a plant includes a plant 7 (seed) sandwiched between 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, the amount of water sprayed on each layer B is adjusted, the pressure when pressing the vegetation sheet after sandwiching the plant, and the heat sealing conditions are adjusted. Can be done. 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 two water-soluble multilayer 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.

  The vegetation sheet of the present invention prepares two water-soluble multilayer films as a base material, and the fall of plants (contents) is suppressed by sandwiching the plants so that the B layer of each film is in contact with the plants. Even when stored in a roll shape for a long time (at the time of moisture absorption), it exhibits blocking resistance.

  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 1-5 and Comparative Examples 1-4
The compound was prepared with the twin-screw extruder by the compounding composition of A layer and B layer shown in Table 1. Next, a layered product of A layer and B layer was formed by coextrusion using a T-die multilayer coextrusion machine by a feed block method. All the laminates were formed with a total thickness of 50 μm and each layer of 25 μm (layer ratio = 1: 1).

Test example 1 (roll rollability: blocking resistance)
A roll having a width of 25 cm and a winding length of 30 m was produced by the above film formation, and stored for 48 hours in a constant temperature and humidity environment of 35 ° C. and 80% Rh, and then the film was pulled out by hand.

The evaluation criteria were as follows.
◎ Unwound with a light force ○ Unwound with a little heavy material × A fairly strong force was required, and the film was deformed or torn.

Test Example 2 (Measurement of water solubility time)
The water solubility time of the laminate was measured by water solubility test A. The evaluation criteria were as follows.

Water-soluble time is 15 seconds or less: ◎
Water solution time exceeds 15 seconds and is 30 seconds or less: ○
Water solubility time exceeds 30 seconds: ×
The test results are also shown in Table 1.

[In the table, “Selvol” indicates the trade name of PVA resin manufactured by Sekisui Specialty Chemicals America. The saponification degree and the 4 wt% aqueous solution viscosity value of each PVA resin are as follows. ]

Product name / saponification degree / 4% aqueous solution viscosity Selvol 203/88 mol% / 4.0 cps
Selvol 205/88 mol% / 5.7 cps
Selvol 310/98 mol% / 10.0 cps
Selvol 418/92 mol% / 17.0 cps

1. 1. Sample film used for water solubility test A 4. Slide mount 3. 1000 ml beaker 4.40 mm × φ8 mm rotor 5. Magnetic stirrer Vegetation sheet 7. Contents (plant)
81. Water-soluble multilayer film (B-layer is the surface that contacts the inner plant)
82. Water-soluble multilayer film (B-layer is the surface that contacts the inner plant)

Claims (9)

A water-soluble multilayer film having an A layer and a B layer on the outermost surface,
(1) The layer A contains 0.5 parts by weight or more of an antiblocking agent having a melting point of 230 ° C. or less with respect to 100 parts by weight of the water-soluble resin.
(2) The B layer does not contain an antiblocking agent having a melting point of 230 ° C. or lower or contains less than 0.5 parts by weight with respect to 100 parts by weight of the water-soluble resin.
A water-soluble multilayer film characterized by that.   The water-soluble multilayer film according to claim 1, wherein the water-soluble resin contains a polyvinyl alcohol-based resin.   The water-soluble multilayer film of Claim 2 whose saponification degree of the polyvinyl alcohol-type resin contained in the said A layer is 92 mol% or more.   The water-soluble multilayer film of Claim 2 or 3 whose saponification degree of the polyvinyl alcohol-type resin contained in the said B layer is less than 92 mol%.   The water-soluble multilayer film according to claim 1, wherein the antiblocking agent is a metal soap.   A vegetation sheet comprising the water-soluble multilayer film according to claim 1.   It is a vegetation sheet formed by sandwiching a plant between two resin films, each of the two resin films being the water-soluble multilayer film according to any one of claims 1 to 5, and the two water-soluble films. Each said B layer of a multilayer film is contacting the said plant, The said two water-soluble multilayer films which oppose are joined in part or all of the area | region which has not pinched | interposed the said plant. The vegetation sheet according to 6.   The vegetation sheet according to claim 7, 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 claim 7 or 8, wherein the plant is turfgrass.

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