JP2021180629A - Agricultural drawn film - Google Patents

Abstract

To provide an agricultural drawn film having good workability during ventilation while maintaining high transparency.SOLUTION: An agricultural drawn film has transparent fine particles and a base resin. The difference in refractive index between the transparent fine particles and the base resin is 0.02 or less. The linear light transmittance at a wavelength of 555 nm is 80% or more. The peeling force tested in accordance with the tackiness test method of JIS K-6732 Appendix is less than 30 gf/3 cm.

Description

The present invention relates to a stretched film for agriculture. More specifically, the present invention relates to an agricultural stretched film having excellent transparency and flexibility, less likely to adhere to each other when the films are overlapped with each other, and having good workability.

Traditionally, farmers who cultivate useful crops have widely used the method of spreading transparent film materials in greenhouses (agricultural houses), tunnels, etc. and cultivating crops in them for the purpose of promoting crop cultivation. It has been adopted.
Conventionally, as such an agricultural film, a soft and hard transparent film such as a vinyl chloride resin film, a polyethylene resin film, a polyethylene terephthalate resin film, and a fluorine resin film has been used. Such films are required to be transparent in consideration of the influence on crops, and in recent years, the development of films that can be used for long-term extension such as 3 years or more is also active.

However, since these resin films are soft and elastic, they can be spread comfortably in any shape of house, but on the other hand, they have the property of adhering to each other when they overlap (called stickiness). There is a drawback that it occurs. This drawback is the ventilation work of the film (the operation of winding and unwinding the film on the side of the house, or the operation of hoisting and lowering the film of the tunnel in order to control the temperature inside the house or the tunnel. ), It takes a lot of time and effort. In particular, when the films are overlapped in a wet state due to rainfall, humidity, etc., the degree of adhesion is strong, which may cause a big problem.

In order to solve such a defect, Patent Document 1 proposes a method of adding a specific amide compound and a specific inorganic fine powder, but the film on the outer surface is significantly contaminated and the ventilation workability is sufficiently satisfied. It wasn't possible. Further, there is a drawback that the transparency is impaired by the addition of the inorganic fine powder.

Further, Patent Document 2 proposes an agricultural soft vinyl chloride resin film in which specific inert solid fine particles are added to form an acrylic resin film on one side of the film. Further, Patent Document 3 proposes an agricultural side covering material in which a synthetic resin layer such as an acrylic resin is formed on at least one side of a vinyl chloride resin film having a thickness of 0.20 mm or more.
However, due to the effect of the acrylic film, stains on the film are easily washed away by rainfall, etc., which is improved. There were drawbacks.

Japanese Unexamined Patent Publication No. 58-69240 Japanese Unexamined Patent Publication No. 62-178341 Japanese Unexamined Patent Publication No. 8-205689

An object of the present invention is to provide an agricultural stretched film having good workability during ventilation work while maintaining high transparency.

As a result of diligent studies to solve the above problems, the present inventors mixed transparent fine particles having a refractive index close to the refractive index of the matrix into the film, and further stretched the film to maintain transparency. I discovered that the sex can be greatly enhanced.
That is, the present invention
[1] A stretched film for agriculture containing transparent fine particles and a base resin, wherein the difference between the refractive index of the transparent fine particles and the refractive index of the base resin is 0.02 or less, and direct light transmission at a wavelength of 555 nm. The stretched film for agriculture, wherein the rate is 80% or more, and the peeling force in the method according to the JIS K-6732 Annex stickiness test method is less than 30 gf / 3 cm.
[2] The stretched film for agriculture according to [1], wherein the difference between the refractive index of the transparent fine particles and the refractive index of the base resin is 0.01 or less.
[3] The transparent fine particles are contained in an amount of 0.2 parts by weight to 1.0 part by weight with respect to 100 parts by weight of the thermoplastic resin constituting the base resin, and the average particle size of the transparent fine particles is 200 nm or more and 30 μm or less. The stretched film for agriculture according to [1] or [2].
[4] The stretched film for agriculture according to any one of [1] to [3], wherein the transparent fine particles are organic fine particles containing an acrylic resin as a main component.
[5] The stretched film for agriculture according to any one of [1] to [4], wherein the thermoplastic resin constituting the base resin is a vinyl chloride resin.
[6] The item according to any one of [1] to [5], wherein the cumulative stretch ratio in the longitudinal direction and the width direction of the agricultural stretch film is 3.0 times or more and 10 times or less. A method for producing the agricultural stretched film.
Regarding.

By using the stretched film for agriculture of the present invention, it is possible to achieve both workability and transparency, which have been a problem in the past. Therefore, it becomes easier to visually check the growing state of the crop from the outside of the film, or it is possible to reduce the burden on the farmer during the ventilation work.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to this aspect.

The agricultural stretched film in the present invention is applicable to either a so-called exterior agricultural film used by spreading and covering an agricultural house (greenhouse) or a tunnel, or a lining agricultural film further extended in a house or a tunnel. You may.
The agricultural film of the present invention is a film made of a base resin in which an additive is mixed with a thermoplastic resin, but the agricultural film of the present invention may be a single layer or a multilayer.

In the present invention, it is important to contain transparent fine particles having a refractive index very close to that of the base resin as a matrix, which makes it possible to improve workability while being transparent as an agricultural film. Become.

The transparent fine particles in the present invention are not particularly limited as long as they have a refractive index close to that of the base resin described later, but are, for example, inorganic fine particles such as silica sol and / or alumina sol, or polymethylmethacrylate and polystyrene. , Nylon 12, silicone, or organic fine particles such as copolymers thereof.
Of these, the latter organic fine particles are preferably used. This is because the organic fine particles soften due to the temperature during film production and thus do not easily damage the production equipment, and because they are hard during use, it is possible to improve workability at the same time.
Further, as the organic fine particles, the organic fine particles containing an acrylic resin as a main component are particularly preferable because they are suitable for transparency and thermal properties and the refractive index can be easily adjusted. Here, the fact that the main component is an acrylic resin means that the main skeleton of the organic fine particles is composed of fine particles made of an acrylic resin, and the copolymer with an arbitrary resin is used in order to match the refractive index with the thermoplastic resin. A polymer may be formed.
The organic fine particles containing an acrylic resin as a main component are not particularly limited as long as they do not melt at the molding temperature of the thermoplastic resin and maintain their shape, and the refractive index can be matched with the refractive index of the thermoplastic resin. However, preferably, it is an acrylic acid copolymer, a styrene-acrylic acid copolymer, a vinyl acetate-acrylic acid copolymer, a vinyl acetate copolymer or the like.

The transparent fine particles are preferably selected from the range in which the primary average particle size is in the range of 200 μm to 30 μm, preferably 1 μm to 20 μm, and in this range, two or more kinds of transparent fine particles having different average particle sizes are selected. It may be used in combination. If the average particle size is too large, the particles are likely to be detached during use, and the particles may be easily damaged from the interface between the particles and the resin. If the average particle size is too small, the particles are exposed. It is not preferable because it becomes difficult to put out and sufficient workability cannot be obtained.

The transparent fine particles preferably have a refractive index difference of 0.02 or less, preferably 0.01 or less, from the base resin. If the difference in refractive index is greater than or equal to the range, sufficient transparency cannot be obtained, which is not preferable.

The content of the transparent fine particles in the agricultural stretched film is 0.2 parts by weight to 1.0 part by weight, preferably 0.3 parts by weight to 0 parts by weight with respect to 100 parts by weight of the thermoplastic resin constituting the base resin. It is 8.8 parts by weight. When the content of the transparent fine particles is 1.0 part by weight or less, the film is less likely to be damaged from the interface between the particles and the base resin, and the film is not fragile. Further, when the content of the transparent fine particles is 0.2 parts by weight or more, the particles are easily exposed and sufficient workability can be obtained, which is preferable.

Further, in the present invention, it is equally important that the film is stretched. When the film containing the transparent fine particles is stretched, the resin as the matrix increases the area in the plane direction but becomes thinner, but the transparent fine particles contained therein are not deformed and are easily exposed on the film surface. This has the effect of greatly improving workability.

As the stretching method, any method may be used as long as the film can be stretched. That is, both of (1) a method of continuously stretching after the step of forming a film, and a method of winding the film after forming the film and stretching the wound film in another step. Can be used. More specifically, for example, a method of performing a stretching process as a step linked to a T-die melt extrusion step, which is a melt casting method, a method of performing a stretching process as a step linked to a film forming process using a calender roll, and a method after winding. Examples thereof include a method of stretching with a stretching device, a method of performing stretching as a step linked to the solution casting method, a method of solution casting, drying and winding, and then stretching with a stretching device.

As a specific method for stretching a film, a method for stretching over one axis can be mentioned. Examples of the uniaxial stretching method include a free width uniaxial stretching method, a method of stretching with a tenter, a method of rolling and stretching with a calendar, and a method of stretching between rolls. Further, as the biaxial stretching method, for example, a method of stretching with a tenter, a method of inflating into a tube shape and stretching, and the like can be mentioned. Further, for these, a small experimental stretching device capable of uniaxial and / or biaxial stretching can also be used.

As the draw ratio, it is desirable that the cumulative draw ratio in the longitudinal direction and the width direction is 2.0 times or more and 10.0 times or less, preferably 3.0 times or more and 8 times or less. If the draw ratio is 2.0 times or more, surface exposure of the particles can be expected. On the other hand, if it is 10.0 times or more, the interface between the particles and the resin is peeled off to form voids, and the film strength is lowered.
The cumulative stretch ratio referred to here is the film thickness immediately after the film is changed from the molten state to the film shape during the film forming process, and the film thickness after being wound through the stretching process and the like (stretching after winding once). When processing is applied, it is defined by the ratio of the film thickness after stretching processing). Here, the film forming process is usually used for producing agricultural films, such as a T-die melt extrusion process which is a melt casting method, a film forming process by a calendar roll, a film forming process by a solution casting method, and a film forming process by an inflation method. The film forming method used is included.
Specifically, the draw ratio can be determined as follows according to the draw processing method used.
[1] When stretching in a process continuous with the film forming process The state immediately after the resin is formed into a film shape from the process in which the resin exists in the molding machine in a molten state or in a flowing state as a bank of a calender roll is defined as before stretching. The thickness ratio of the film before stretching and after stretching when the state after winding and cooling the film is defined as after stretching.
[2] In the case of a method of stretching after drying and winding with a stretching device The thickness of the film immediately after the film is changed from the molten state to the film shape during the film forming process and the thickness of the film after being wound after the stretching process. ratio.

In the present invention, the base resin refers to a resin composition (also referred to as "base resin composition") in which an additive is mixed with a thermoplastic resin.
The thermoplastic resin constituting the base resin of the present invention includes vinyl chloride resin usually used for agricultural films, polyolefin resin such as polyethylene and ethylene-vinyl acetate copolymer, and polyester resin such as polyethylene terephthalate. Examples thereof include a resin, but in the present invention, it is particularly preferable to use a vinyl chloride resin. This is because the vinyl chloride resin is excellent in transparency and flexibility, but has the property of easily adhering when the films overlap each other.
The vinyl chloride resin refers to a copolymer containing vinyl chloride as a main component in addition to polyvinyl chloride. Examples of the monomer compound that can be copolymerized with vinyl chloride include vinylidene chloride, ethylene, propylene, acrylonitrile, maleic acid, itaconic acid, acrylic acid, methacrylic acid, vinyl acetate and the like. These vinyl chloride resins may be produced by any of conventionally known production methods such as an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, and a bulk polymerization method.
Thermoplastic resins include known plasticizers, lubricants, heat stabilizers, organic phosphate esters or metal salts, antistatic agents, antifungal agents, anti-fog agents, UV absorbers, and light, known as agricultural films. Stabilizers, colorants, stabilizers, antioxidants, inorganic fillers, antistatic agents, heat insulating agents, fungicides, algae-proofing agents and the like can be blended.

Examples of the plasticizer include phthalic acid derivatives such as g-n-octylphthalate, di-2-ethylhexylphthalate, dibenzylphthalate and diisodecylphthalate; isophthalic acid derivatives such as dioctylphthalate; Adipic acid derivative; Maleic acid derivative such as di-n-butylmalate; Citric acid derivative such as tory n-butylcitrate; Itaconic acid derivative such as monobutylitaconate; Oleic acid derivative such as butyloleate; Etc., Citric acid derivatives, etc .; In addition, epoxidized soybean oil, epoxidic resin-based plasticizers, and the like can be mentioned. Further, in order to impart flexibility to the resin film, the plasticizer is not limited to the above-mentioned, and for example, a thermoplastic polyurethane resin, polyvinyl acetate, or the like can be used.

As lubricants or heat stabilizers, fatty acid-based lubricants, fatty acid amide-based lubricants, ester-based lubricants, polyethylene waxes, liquid paraffins, killer such as organic phosphite compounds, phenols, β, which are generally used for agricultural films. -A diketone compound and the like can be mentioned.

Examples of the organic phosphate ester include triisopropylphenyl phosphate, isodecyldiphenyl phosphate, tris (isopropylphenyl) phosphate, tributyl phosphate, triethyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, octyldiphenyl phosphate, and trixylenyl. Examples thereof include phosphate, and among them, tricredyl phosphate and trixylenyl phosphate are particularly preferable.

Examples of the antistatic agent include polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene alkyl ether, glycerin fatty acid ester, sorbitan fatty acid ester and the like.
Examples of the anti-fog agent include nonionic surfactants, and specific examples thereof include sorbitan-based, glycerin-based, polyethylene glycol-based surfactants, and alkylphenol alkylene oxide adducts.
Examples of the anti-fog agent include a fluorine-based surfactant and a silicone-based surfactant.

Examples of the ultraviolet absorber include ultraviolet absorbers such as benzoate-based, salicylic acid-based, cyanoacrylate-based, benzophenone-based, benzotriazole-based, and triazine-based (triaryltriazine-based). Above all, it is desirable to use a benzophenone-based ultraviolet absorber or a benzotriazole-based ultraviolet absorber. These ultraviolet absorbers may be used alone or in combination of two or more, and the amount used is 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight per 100 parts by weight of the thermoplastic resin.

Examples of the light stabilizer include 4-cyclohexinoyloxy-2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4- (o-chlorobenzoyloxy)-. Examples thereof include hindered amine compounds such as 2,2,6,6-tetramethylpiperidine.

Examples of the antioxidant include phenol-based, thiodipropionic acid ester, aliphatic sulfide and disulfide-based antioxidants, and specific examples thereof include 2,6-di-tert-butyl-4-methylphenol. , 2,2'-Methylenebis (6-tert-butyl-4-ethylphenol), dilaurylthiodipropionate and the like.

Examples of the inorganic filler include oxides such as calcium, magnesium and aluminum, hydroxides, carbonates, silicates and the like, and composites thereof.
Examples of the heat insulating agent include inorganic compound particles that absorb light rays in the far infrared region of 4000 nm to 25000 nm, and examples thereof include magnesium oxide, calcium oxide, aluminum oxide, silicon oxide, lithium hydroxide, magnesium hydroxide, and calcium hydroxide. Aluminum hydroxide, magnesium carbonate, calcium carbonate, calcium sulfate, magnesium sulfate, aluminum sulfate, lithium phosphate, calcium phosphate, magnesium silicate, calcium silicate, aluminum silicate, calcium aluminate, magnesium aluminate, sodium aluminosilicate, potassium aluminosilicate, Calcium alminosilicate, kaolin, clay, talc, mica, zeolite, hydrotalcite compounds, lithium-aluminum composite hydroxide, aluminum-lithium-magnesium composite carbonate compound, aluminum-lithium-magnesium composite silicate hydroxide, magnesium -Aluminum-silicon composite hydroxide, magnesium-aluminum-silicon composite sulfate compound, magnesium-aluminum-silicon composite carbonate compound, metal composite hydroxide salt containing a plurality of anions, and the like can be mentioned.

Anti-adhesive agents include at least one mixture selected from methylene bisstearoamide, ethylene bislauryl amide, N, N'-diorail adipamide, N, N'-distearyl adipamide. ..
As lubricants or heat stabilizers, fatty acid-based lubricants, fatty acid amide-based lubricants, ester-based lubricants, polyethylene waxes, liquid paraffins, killer such as organic phosphite compounds, phenols, β, which are generally used for agricultural films. -Diketone compounds and the like can be mentioned. As the β-diketone compound, dibenzoylmethane, methoxybenzoyl / benzoylmethane, chlorbenzoyl / benzoylmethane, palmitylbenzoylmethane and the like are suitable.

In the stretched film for agriculture of the present invention, in order to blend various additives, each required amount is weighed, and a blender such as a ribbon blender, a Banbury mixer, a henschel mixer, a super mixer, a single-screw or twin-screw extruder, or a roll is used. , A kneader, or any other conventionally known compounding machine or mixer may be used. In order to form the resin composition thus obtained into a film, a method known per se, for example, melt extrusion molding method (including T-die method and inflation method), calendar processing, roll processing, extrusion molding processing, etc. Methods such as blow molding, inflation molding, melt casting, pressure molding, paste processing, and powder molding can be preferably used.

The thickness of the stretched film for agriculture of the present invention is preferably in the range of 0.01 to 1 mm, more preferably 0.05 to 0.5 mm, and even more preferably 0.05 to 0.05 in terms of strength and cost. It is 0.2 mm. If it is less than this range, there is a problem in strength, and if it exceeds this range, molding is difficult and there is a problem in extension workability.
As the stretched film for agriculture of the present invention, a film in which an anti-fog coating film is further applied to the inside during house expansion may be used. Further, a dust-proof coating film may be formed on the outer surface of the house when the stretched agricultural film is coated on the house.

Examples of the anti-fog coating film include a composition containing a binder resin such as an inorganic colloidal sol and / or a thermoplastic resin as a main component. Preferably, an anti-fog coating film containing an inorganic colloidal substance and a hydrophilic organic compound as main components or an anti-fog coating film containing an inorganic colloidal substance and an acrylic resin as main components can be used. Further, the binder resin may not be added, and an inorganic substance such as colloidal silica or colloidal alumina may be laminated. The anti-fog coating film that can be formed in the present invention is described in, for example, Japanese Patent Application Laid-Open No. 2008-06645.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

[Examples 1 to 7, Comparative Examples 1 to 4]
(1) Manufacture of PVC-based resin film Polyvinyl chloride (polymerization degree = 1300) 100 parts by weight Di-2-ethylhexylphthalate 45 parts by weight Tricklesyl phosphate 5 parts by weight Epoxy resin (trade name "EP-828") 1 .5 parts by weight Ba-Zn-based liquid stabilizer 1 part by weight Barium stearate 0.2 parts by weight Zinc stearate 0.4 parts by weight Solbitan monopalmitate 1.5 parts by weight β-diketone compound (dibenzoylmethane) 0.1 By weight benzotriazole-based ultraviolet absorber 0.04 parts by weight (trade name "TINUVIN-P")
Fluorosurfactant (trade name "Unidyne DS-401") 0.2 parts by weight

The above-mentioned resin raw materials and resin additives were weighed, and a predetermined amount of particles having the characteristics shown in Table 1 was further added thereto. After stirring and mixing these with a super mixer for 10 minutes, the mixture is kneaded on a roll heated to 165 ° C., and has a thickness of 0.075 mm and a thickness of 0.050 mm by an L-shaped calendar device and a tenter stretching device connected thereto. A transparent vinyl chloride resin film was produced. The refractive index of the base resin in the state where the particles shown in Comparative Example 1 are not added is 1.53. Further, the addition amount of the fine particles in Table 1 is an addition amount (parts by weight) in which the weight of the entire vinyl chloride resin film is 100 parts by weight.

(2) Evaluation of film The performance of the film was evaluated by the following method, and the results are shown in Table 1.
(I) Optical characteristics The films produced in Examples and Comparative Examples were measured for 555 nm direct light transmittance with a spectrophotometer "UV-2450" manufactured by Shimadzu Corporation.
The evaluation criteria are as follows.
Straight light transmittance ◎… Straight light transmittance of 85.0% or more.
○… The direct light transmittance is 80.0% or more and less than 85.0%.
×: The direct light transmittance is less than 80.0%.

(Ii) Workability Tensile properties: The films obtained in Examples and Comparative Examples were evaluated by a method according to JIS K-6732 Annex Stickiness Test Method. The width of the material piece was 3 cm, the load cell capacity was 1 kg, the test speed (peeling speed) was 100 mm per minute, and the chart speed was 50 mm per minute.
The evaluation criteria are as follows.
Workability ◎… Peeling force is less than 20 gf / 3 cm.
◯: The peeling force is 20 gf / 3 cm or more and less than 30 gf / 3 cm.
×: The peeling force is 30 gf / 3 cm or more.

From the results of Examples and Comparative Examples, it can be said that the stretched film for agriculture in the present invention has good workability during ventilation work while maintaining high transparency.

Claims (6)

An agricultural stretched film containing transparent fine particles and a base resin, the difference between the refractive index of the transparent fine particles and the refractive index of the base resin is 0.02 or less, and the direct light transmittance at a wavelength of 555 nm is 80. % Or more, and the peeling force in the method according to the JIS K-6732 Annex stickiness test method is less than 30 gf / 3 cm. The stretched film for agriculture according to claim 1, wherein the difference between the refractive index of the transparent fine particles and the refractive index of the base resin is 0.01 or less. Claim 1 that the transparent fine particles are contained in an amount of 0.2 parts by weight to 1.0 part by weight with respect to 100 parts by weight of the thermoplastic resin constituting the base resin, and the average particle size of the transparent fine particles is 200 nm or more and 30 μm or less. Or the stretched film for agriculture according to 2. The stretched film for agriculture according to any one of claims 1 to 3, wherein the transparent fine particles are organic fine particles containing an acrylic resin as a main component. The stretched film for agriculture according to any one of claims 1 to 4, wherein the thermoplastic resin constituting the base resin is a vinyl chloride resin. The agricultural stretched film according to any one of claims 1 to 5, wherein the cumulative stretch ratio in the longitudinal direction and the width direction of the agricultural stretched film is 3.0 times or more and 10 times or less. Manufacturing method.