Agricultural polyvinyl chloride resin film

Abstract

To provide a vinyl chloride-based resin film for agriculture which can suppress initial drip-proofness and stickiness, and can maintain long-term drip-proofness.SOLUTION: A vinyl chloride-based resin film for agriculture contains a vinyl chloride-based resin, a plasticizer, a drip-proof agent and a lubricant, wherein the drip-proof agent contains an ester compound A of at least one polyhydric alcohol selected from sorbitan, glycerol, diglycerol and polyglycerol, and at least one fatty acid selected from a stearic acid and a palmitic acid, and an addition compound B obtained by adding an alkylene oxide to the ester compound A, and the lubricant contains methylene bis-stearic acid amide and ethylene bis-stearic acid amide.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to a vinyl chloride resin film for agricultural use. [Background technology]

[0002] Polyvinyl chloride resin films are widely used as covering materials (also called agricultural covering materials) for greenhouse horticulture, such as agricultural tunnels and greenhouses, because they are inexpensive, transparent, and have excellent heat retention and strength.

[0003] Vinyl chloride resin films contain various additives depending on their application. For example, when used as an agricultural covering, plasticizers are used to give the film flexibility in order to facilitate stretching and ventilation. In addition, the film contains additives such as anti-drip agents to suppress the occurrence of diseases caused by water droplets adhering to the film surface and falling onto crops inside.

[0004] The effects of these additives in polyvinyl chloride resin films are required to last for the duration that the film is in use. For example, in the case of agricultural coverings, the film is replaced with a new one every 1 to 2 years.

[0005] However, in recent years, due to reasons such as labor shortages among farmers and the need for resource conservation, there has been a demand for agricultural covering materials that can be deployed for extended periods. However, among additives, it has been difficult for anti-drip agents to maintain their effectiveness for as long as a year. Therefore, many proposals have been made for anti-drip agents that can maintain their anti-drip properties for a long period of time by specifying the type of anti-drip agent or combining it with other additives for vinyl chloride resin films (Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-123795 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, when attempting to maintain water resistance over a long period, the initial water resistance tends to weaken, while prioritizing initial water resistance can make it difficult to maintain water resistance over a long period.

[0008] Furthermore, agricultural coverings, especially during the summer, require rolling up the coverings to allow for ventilation due to the rapid rise in temperature inside greenhouses. After ventilation is complete, the rolled-up coverings are lowered, but sunlight hitting the rolled-up coverings causes them to retain heat, leading to a problem of stickiness where the coverings stick together and become difficult to lower. This stickiness is particularly noticeable in the early stages of use, but improves as sand and dust accumulate on the surface of the coverings over time. In other words, the goal is to suppress the stickiness at the beginning of use, and to achieve this, lubricants that easily transfer to the film surface are added. However, selecting an anti-drip agent that easily migrates to the film surface in order to improve initial water resistance tends to worsen the suppression of stickiness, and it has still been difficult to achieve both initial water resistance, suppression of stickiness, and long-term water resistance.

[0009] The present invention aims to provide an agricultural polyvinyl chloride resin film that can maintain initial water-repellent properties, suppress stickiness, and sustain water-repellent properties over a long period of time. [Means for solving the problem]

[0010] The present invention relates to an agricultural vinyl chloride resin film comprising a vinyl chloride resin, a plasticizer, a drip-proofing agent, and a lubricant, The anti-drip agent comprises an ester compound A of at least one polyhydric alcohol selected from sorbitan, glycerin, diglycerin, and polyglycerin, and at least one fatty acid selected from stearic acid and palmitic acid, and an adduct compound B obtained by adding alkylene oxide to the ester compound A, wherein the content ratio is 1 part adduct compound B by mass, and 2 to 4 parts ester compound A. The lubricant comprises methylenebisstearamide and ethylenebisstearamide, and its content ratio is such that, by mass ratio, ethylenebisstearamide is 1 part and methylenebisstearamide is more than 0.5 parts and not more than 5 parts.

[0011] Furthermore, the content of the anti-drip agent is characterized to be 1 part by mass or more and 3 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0012] Furthermore, the lubricant content is characterized by being 0.3 parts by mass or more and 0.6 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0013] Furthermore, the ester compound A is sorbitan stearate and / or sorbitan palmitate. The aforementioned adduct B is characterized in that it is an ethylene oxide adduct of sorbitan stearate and / or an ethylene oxide adduct of sorbitan palmitate. [Effects of the Invention]

[0014] The present invention can provide an agricultural polyvinyl chloride resin film that offers initial water-repellent properties, suppresses stickiness, and maintains water-repellent properties for a long period of time. [Brief explanation of the drawing]

[0015] [Figure 1]A diagram for explaining an instrument for evaluating the drip-proof property of the present invention, showing (a) a vinyl chloride pipe, (b) a side view of the state where a film is extended on the vinyl chloride pipe, and (c) a front view of the state where a film is extended on the vinyl chloride pipe. [Figure 2] A diagram for explaining the method for evaluating the drip-proof property of the present invention. [Figure 3] A schematic diagram for explaining the timing of the flow of water droplets when evaluating the drip-proof property, showing (a) the state where water droplets are attached and (b) the state where some of the water droplets have flowed.

Embodiments for Carrying Out the Invention

[0016] The present invention is an agricultural vinyl chloride resin film containing a vinyl chloride resin, a plasticizer, a drip-proof agent, and a lubricant.

[0017] In the present invention, examples of the vinyl chloride resin include polyvinyl chloride, copolymers of vinyl chloride monomer and other monomers copolymerizable with vinyl chloride, copolymers of vinyl chloride monomer and higher vinyl ether, or mixtures thereof. Examples of monomers copolymerizable with vinyl chloride include olefin monomers and vinyl-based monomers such as ethylene, propylene, maleic ester, methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, methacrylic acid, acrylic acid, and vinyl acetate.

[0018] In the present invention, the plasticizers include general phthalate ester plasticizers such as dioctyl phthalate (DOP), diisononyl phthalate (DINP), butyl benzyl phthalate (BBP), diisodecyl phthalate (DIDP), and diundecyl phthalate (DUP); general fatty acid ester plasticizers such as dioctyl adipicate (DOA), dioctyl sebatate (DOS), and dioctyl azelaate (DOZ); and trioctyl trimellitate. Examples of plasticizers include trimellitic acid ester plasticizers represented by esters (TOTM), polyester plasticizers represented by polypropylene adipates, and other polymeric plasticizers, as well as sebatic acid plasticizers, general plasticizers such as chlorinated paraffins, and phosphate ester plasticizers such as tricresyl phosphate (TCP), trixylyl phosphate (TXP), tris(isopropylphenyl) phosphate, tributyl phosphate, triethyl phosphate, triphenyl phosphate, and triethylphenyl phosphate. These plasticizers can be used individually or in combination of two or more.

[0019] In the present invention, the plasticizer content is preferably 40 parts by mass or more and 60 parts by mass or less per 100 parts by mass of vinyl chloride resin. If the plasticizer content is less than 40 parts by mass, it is difficult to obtain sufficient flexibility for use as an agricultural covering material, and if it exceeds 60 parts by mass, the plasticizer migrates to the surface of the resulting film, making the surface prone to stickiness, which is difficult to suppress.

[0020] In the present invention, the anti-drip agent includes an ester compound A of at least one polyhydric alcohol selected from sorbitan, glycerin, diglycerin, and polyglycerin, and at least one fatty acid selected from stearic acid and palmitic acid, and an addition compound B obtained by adding an alkylene oxide to the ester compound A.

[0021] Specifically, as ester compound A, one or more of the following may be used in combination: sorbitan stearate, sorbitan palmitate, glycerin stearate, glycerin palmitate, diglycerin stearate, diglycerin palmitate, polyglycerin sorbitan stearate, polyglycerin sorbitan palmitate, etc. In this invention, sorbitan fatty acid esters such as sorbitan stearate include monoesters, diesters, triesters, and mixtures thereof, and compounds esterified with two or more fatty acids to one polyhydric alcohol are also included in ester compound A.

[0022] Examples of alkylene oxides that constitute adduct B include ethylene oxide and propylene oxide. Specifically, adduct B may be one or more of the following, in combination: sorbitan stearate-ethylene oxide 1 molar adduct, sorbitan stearate-ethylene oxide 2 molar adduct, sorbitan stearate-ethylene oxide 3 molar adduct, sorbitan stearate-propylene oxide 3 molar adduct, glycerin palmitate-ethylene oxide 2 molar adduct, etc. The number of moles of alkylene oxide to be added is preferably 1 to 10 moles.

[0023] In the present invention, preferably, the ester compound A is sorbitan stearate and / or sorbitan palmitate as the anti-drip agent, and the adduct compound B is an ethylene oxide adduct of sorbitan stearate and / or an ethylene oxide adduct of sorbitan palmitate. With these combinations, initial anti-drip properties, suppression of stickiness, and long-term anti-drip properties can be further sustained.

[0024] In the present invention, the content ratio of ester compound A to adduct compound B is such that, by mass ratio, adduct compound B is 1 part and ester compound A is 2 to 4 parts. If the content ratio of ester compound A to adductor compound B is less than 2, that is, if the content ratio of adductor compound B increases, the long-term anti-drip properties of the resulting film will be inferior. Although not certain, it is thought that as the content of alkylene oxide in adductor compound B increases, the anti-drip agent is more likely to migrate to the film surface due to differences in compatibility with vinyl chloride resin, making it difficult to maintain the anti-drip properties of the resulting film over a long period. Also, if the content ratio of ester compound A exceeds 4, the anti-drip agent is less likely to migrate to the film surface, making it difficult for the resulting film to exhibit initial anti-drip properties.

[0025] In the present invention, the content of the anti-drip agent is preferably 1 part by mass or more and 3 parts by mass or less per 100 parts by mass of the vinyl chloride resin. If the content of the anti-drip agent is too low, the anti-drip properties will not be sufficient, and if the content of the anti-drip agent is too high, not only will the cost increase, but the stickiness of the resulting film tends to be difficult to suppress, and bloom may occur, causing the film surface to whiten.

[0026] In the present invention, the lubricant comprises methylenebisstearamide and ethylenebisstearamide, with a mass ratio of ethylenebisstearamide to methylenebisstearamide of 0.5 to 5. If the content ratio of methylenebistearate to ethylenebistearate is 0.5 or less, the surface of the resulting film will whiten (poor appearance), and if the content ratio exceeds 5, it will be difficult to suppress the stickiness of the resulting film. Here, "whitening of the film surface" refers to the phenomenon where a transparent film becomes cloudy and white due to the solidification of components that have migrated to the film surface over time. Whitened films reduce visibility and are difficult to use as agricultural covering materials. The degree of such whitening can be indicated, for example, by measuring the haze using a haze meter on a film that has been accelerated for one week in a constant temperature chamber at 40°C and 90% humidity. In this invention, it is preferable that the haze measured by this method is less than 15%.

[0027] In the present invention, the content of the lubricant is preferably 0.3 to 0.6 parts by mass with respect to 100 parts by mass of the vinyl chloride resin.

[0028] As the lubricant, those other than methylene bisstearic acid amide and ethylene bisstearic acid amide may be contained as long as the effects of the present invention are not impaired. For example, metal soaps such as zinc stearate, barium stearate, and calcium stearate; hydrocarbons such as liquid paraffin, polyethylene waxes, and chlorinated hydrocarbons; fatty acids and fatty acid amides such as stearic acid, stearic acid amide, and palmitic acid amide; and lubricants such as fatty acid esters such as butyl stearate, cetyl palmitate, and monoglyceryl stearate can be used.

[0029] Additives such as an antifogging agent, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a filler, and a pigment can be added to the present invention as necessary.

[0030] Examples of the antifogging agent that can be used in the present invention include fluorine-based compounds having at least one of a fluorine-containing group and a hydroxyl group or an alkylene oxide group in one molecule. Examples of the fluorine-containing group include a perfluoroalkyl group (C n H 2n+1 group), a perfluoroalkoxy group (C n F 2n+1 O group), a polyfluoroalkyl group (H m C n F 2n+1-m group), a perfluoroalkenyl group (C n F 2n-1 group), a polyfluoroalkenyl group (H m C n F 2n-1-m group), etc. (where m is an integer of 1 to 3 and n is an integer of 3 to 20). Examples of the alkylene oxide group include (C2H4O) n , (C3H6O) n , etc. (where n is an integer of 1 to 30). The addition amount of these fluorine-based compounds is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part by mass, with respect to 100 parts by mass of the vinyl chloride resin.

[0031] Examples of heat stabilizers that can be used in the present invention include metal soaps such as zinc stearate, barium stearate, calcium stearate, barium ricinoleate, calcium laurate, and calcium oleate; Mg-Zn, Ca-Zn, and Ba-Zn composite metal soaps; epoxy compounds such as epoxidized soybean oil; organic phosphite stabilizers such as diphenyldecyl phosphite, triphenyl phosphite, tris(nonylphenyl) phosphite, tridecyl phosphite, tris(2-ethylhexyl) phosphite, tristearyl phosphite, and octyldiphenyl phosphite; and tin-based stabilizers such as dibutyltin laurate, dibutyltin malate, organotin mercaptide, and organotin sulfonamide. These stabilizers can be used individually or in combination of two or more. The heat stabilizer content is preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of vinyl chloride resin.

[0032] Light stabilizers that can be used in the present invention include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6-tetramethyl-4-piperidyl benzoate, N-(2,2,6,6-tetramethyl-4-piperidyl)dodecyl succinimide, and 1-[(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]-2,2,6,6-tetramethyl-4-piperidyl(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl N,N'-Bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, Bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, Bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl) malonate, N,N'-Bis(2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine, Tetra(2,2,6,6-tetramethyl-4-piperidyl) butanetetracarboxylate, Bis(2,2,6,6- Tramethyl-4-piperidyl)di(tridecyl)butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)di(tridecyl)butanetetracarboxylate, 3,9-bis{1,1-dimethyl-2-[tris(2,2,6,6-tetramethyl-4-piperidyloxycarbonyloxy)butylcarbonyloxy]ethyl}-2,4,8,10-tetraoxyspiro[5,5]undecane, 3,9-bis{1,1-dimethyl-2-[tris(1,2,2,6,6-pentamethyl-4-piperidyloxy]ethyl} Bonyloxy)butylcarbonyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,5,8,12-tetrakis{4,6-bis[N-(2,2,6,6-tetramethyl-4-biperidyl)butylamino]-1,3,5-triazine-2-yl}-1,5,8,12-tetraazadodecane, 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol / dimethyl succinate condensate, 2-tert-octylamino-4,6-dichloro-s-triazine / N,N'-bis(2,2,6,Examples include hindered amine-based light stabilizers such as 6-tetramethyl-4-piperidyl)hexamethylenediamine condensate and N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine / dibromoethane condensate.

[0033] Examples of ultraviolet absorbers that can be used in the present invention include salicylic acid esters, benzotriazoles, hydroxybenzophenones, and acrylonitrile-substituted derivatives. These ultraviolet absorbers can be used individually or in combination of two or more. Specifically, 2-hydroxybenzophenones such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-ethoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 5,5'-methylenebis(2-hydroxy-4-methoxybenzophenone); 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-dicumylphenyl)benzotriazole Examples of UV absorbers include 2-(2'-hydroxyphenyl)benzotriazoles such as 2,2'-methylenebis(4-tert-octyl-6-benzotriazole)phenol; benzoates such as phenyl salicylate, resorcinol monobenzoate, 2,4-di-tert-butylphenyl-3',5'-di-tert-butyl-4'-hydroxybenzoate, and hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate; oxanilides such as 2-ethoxy-4'-dodecyloxanilide; and cyanoacrylates such as ethyl-α-cyano-β,β-diphenyl acrylate and methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate. These UV absorbers may be used individually or in combination of two or more types.

[0034] Examples of fillers that can be used in this invention include calcium carbonate, titanium dioxide, aluminum hydroxide, talc, feldspar, silica, and hydrotalcite.

[0035] The agricultural vinyl chloride resin film of the present invention is manufactured by known methods. Specifically, a vinyl chloride resin composition, to which the above-mentioned plasticizer, anti-drip agent, lubricant, and various additives as needed are added to a vinyl chloride resin, is formed into a film of a desired thickness by appropriate means such as calendering, extrusion, or inflation. The film thickness is preferably about 0.05 to 0.2 mm.

[0036] The present invention provides an agricultural polyvinyl chloride resin film that can maintain initial water-repellent properties, suppress stickiness, and maintain water-repellent properties over a long period of time.

[0037] In this invention, the suppression of stickiness is evaluated by the peel load, which is measured as follows. The peel load is measured by the following method, with reference to JIS K 6732. A polyvinyl chloride resin film measuring 400 mm in length, 300 mm in width, and 0.1 mm in thickness is stretched over a constant temperature water bath at 50°C. At this time, the side facing the water surface of the constant temperature water bath is considered the back of the film, and the side exposed to the outside air is considered the front of the film. After 24 hours of stretching, two test pieces measuring 150 mm in length and 100 mm in width are prepared from the film. These test pieces are then pressed together with a rubber roll (load 1 kg) so that the film surface of one test piece overlaps with the film back of the other test piece. Subsequently, the pressed test pieces are sandwiched between 1 mm thick glass plates, and a 2 kg weight is placed on the side where the film surface is located. The test is then heated in an 80°C oven for 2 hours. After that, it is left to stand at room temperature for at least 1 hour. A measuring test piece measuring 30 mm in length and 70 mm in width is cut from the compressed test piece. Each of the two compressed measuring test pieces is fixed to a grip, and a tensile testing machine (A&D Company, Ltd., "Tensilon Universal Material Testing Machine") is used to pull until the entire piece is separated. At this time, the peeling speed is set to 100 ± 10 mm per minute, and the peel load / N is defined as the average strength from the point where the minimum strength is reached after passing the initial maximum strength, up to a peeling distance of approximately 40 mm. The conditions of heating in an 80°C oven for 2 hours with a 2kg weight on top are based on the assumption of a greenhouse with the film rolled up during the summer.

[0038] As mentioned above, a smaller measured peel load indicates that stickiness is suppressed. If stickiness is suppressed, when ventilating agricultural covering materials, the rolled-up covering material is lowered after ventilation is complete, but sunlight hits the rolled-up covering material, causing it to accumulate heat and stick together, preventing it from becoming impossible to lower. In this invention, it is preferable that the peel load is 0.4 N or less.

[0039] In this invention, water resistance (initial and long-term) is evaluated as follows.

[0040] (Initial) As shown in Figure 1, an agricultural polyvinyl chloride resin film 1 is stretched over the opening of a polyvinyl chloride pipe 2, which is 76 mm in diameter and 140 mm in length, cut at an angle of α = 15°, and secured with a band 3. As shown in Figure 2, the start time is defined as when the polyvinyl chloride pipe 2 with the film 1 stretched over it is placed in a constant temperature water bath 4 at 50°C, and the time is measured until steam from the water surface 5 in the constant temperature water bath 4 condenses on the back surface of the film 1 and the water droplets run off. The side facing the water surface in the constant temperature water bath is considered the back surface of the film, and the side exposed to the outside air is considered the front surface of the film.

[0041] (Long-term) Similar to the initial evaluation, an agricultural polyvinyl chloride resin film 1 is stretched over the opening of a polyvinyl chloride pipe 2, which is 76 mm in diameter and 140 mm in length, cut at an angle of α = 15°, and secured with a band 3. As shown in Figure 2, the polyvinyl chloride pipe 2 with the film 1 stretched over it is placed in a constant temperature water bath 4 at 70°C and removed after 200 hours. After that, water droplets on the back of the film are wiped off, and the time it takes for condensed water droplets to flow off the film 1 is measured in the same manner as the initial drip-proof evaluation. In this invention, "long term" refers to use for one year.

[0042] In terms of initial and long-term water resistance, the shorter the time it takes for condensed water droplets to run off the film, the better the water resistance. In this invention, the initial exposure time is preferably 20 minutes or less, and the long-term exposure time is preferably 40 minutes or less, with both the initial and long-term exposure times being more preferably 20 minutes or less. If the exposure time exceeds 40 minutes, the water droplets adhering to the film surface will grow larger over time and then fall off, making it difficult to prevent diseases caused by water droplets falling on crops inside the greenhouse. [Examples]

[0043] The present invention will be described in more detail below with reference to examples and comparative examples. The present invention is not limited to these examples.

[0044] [Examples 1-11, Comparative Examples 1-9] Based on the formulations shown in Tables 1 and 2, each material was mixed, and then films with a thickness of 0.1 mm and a width of 300 mm were produced using a double-roll mill. The obtained vinyl chloride resin films were evaluated for their appearance, stickiness suppression, and drip-proof properties, and the results are shown in Table 1. Note that the formulations in the table are expressed in parts by mass.

[0045] The materials shown in Table 1 are as follows: Vinyl chloride resin: Polyvinyl chloride Plasticizer: DOP Anti-drip agent 1: Sorbitan stearate (ester compound A) Anti-drip agent 2: Sorbitan palmitate (ester compound A) Anti-drip agent 3: Diglycerin stearate (ester compound A) Anti-drip agent 4: Polyglycerin stearate (ester compound A) Anti-drip agent 5: Sorbitan stearate EO adduct (adduct compound B) Anti-drip agent 6: Sorbitan palmitate EO adduct (adduct compound B) Lubricant 1: Methylene bis-stearamide (manufactured by Mitsubishi Chemical Corporation, product name "Bis-Amide LA") Lubricant 2: Ethylene bis-stearamide (manufactured by Kao Corporation, product name "Kao Wax EBG") Heat stabilizer 1: Zinc octoate Heat stabilizer 2: Ba-Zn type Light stabilizer: Hindered amine type (HALS) UV absorber: 2-hydroxy-4-n-octoxybenzophenone

[0046] [Film appearance] A polyvinyl chloride resin film measuring 400 mm in length, 300 mm in width, and 0.1 mm in thickness was accelerated for one week in a constant temperature chamber at 40°C and 90% humidity, and then the haze was measured using a haze meter (manufactured by Suga Test Instruments Co., Ltd., product name "HZ-V3").

[0047] [Suppresses stickiness] A polyvinyl chloride resin film measuring 400 mm in length, 300 mm in width, and 0.1 mm in thickness was stretched over a constant temperature water bath at 50°C. The water surface side of the bath was considered the back of the film, and the side exposed to the outside air was considered the front. After 24 hours, two test pieces measuring 150 mm in length and 100 mm in width were cut from the film. These test pieces were then pressed together using a rubber roll (with a load of 1 kg) so that the film surface of one piece overlapped with the film back of the other. The pressed test pieces were then sandwiched between 1 mm thick glass plates, and a 2 kg weight was placed on the side where the film surface was located. The test pieces were then heated in an 80°C oven for 2 hours. Afterward, they were left to stand at room temperature for at least 1 hour. A measuring test piece measuring 30 mm in length and 70 mm in width was cut from the compressed test piece. Each of the two compressed measuring test pieces was fixed to a grip and pulled using a tensile testing machine (A&D Company, Ltd., "Tensilon Universal Material Tester") until they were completely separated. The peeling speed was set to 100 ± 10 mm per minute, and the peel load / N was defined as the average strength from the point where the minimum strength was reached after exceeding the initial maximum strength, up to a peeling distance of approximately 40 mm. The peel load was measured according to JIS K 6732.

[0048] [Water-resistant] (Initial) As shown in Figure 1, a polyvinyl chloride resin film 1 was stretched over the opening of a polyvinyl chloride pipe 2 (manufactured by AS ONE, product name "PVC pipe") with a diameter of 76 mm and a length of 140 mm, which had been cut with an α = 15° inclination, and secured with a band 3. As shown in Figure 2, the start time was defined as when the polyvinyl chloride pipe 2 with the film 1 stretched over it was placed in a constant temperature water bath 4 at 50°C, and the time until the steam from the water surface 5 in the constant temperature water bath 4 condensed on the back surface of the film 1 and the water droplets flowed away was measured. Similar to the initial (long-term) evaluation, an agricultural polyvinyl chloride resin film 1 was stretched over the opening of a 76mm diameter, 140mm long polyvinyl chloride pipe 2 (manufactured by AS ONE, product name "PVC pipe"), which had been cut with an α=15° incline, and secured with a band 3. As shown in Figure 2, the polyvinyl chloride pipe 2 with the film 1 stretched over it was placed in a 70°C constant temperature water bath 4 and removed after 200 hours. After that, the water droplets on the back of the film were wiped off, and the time it took for the condensed water droplets to flow off the film 1 was measured in the same manner as the initial drip-proof evaluation.

[0049] [Table 1]

[0050] [Table 2]

[0051] As shown in Tables 1 and 2, according to the present invention, a vinyl chloride resin film can be obtained that contains ester compound A and adduct compound B, which are specific anti-drip agents, in specific ratios, and methylenebis-stearate amide and ethylene-bis-stearate amide, which are lubricants, in specific ratios, thereby providing initial anti-drip properties, suppression of stickiness, and long-term anti-drip properties. This vinyl chloride resin film is suitable for agricultural covering materials. [Explanation of Symbols]

[0052] 1. Vinyl chloride resin film 2. Vinyl chloride pipe 3. Band 4. Constant temperature water bath 5. Water surface α Incline angle

Claims

[Claim 1] A vinyl chloride resin film for agricultural use, comprising a vinyl chloride resin, a plasticizer, a drip-proofing agent and a lubricant, The anti-drip agent comprises sorbitan, an ester compound A of at least one fatty acid selected from stearic acid and palmitic acid, and an addition compound B obtained by adding ethylene oxide to the ester compound A. The content of the anti-drip agent is 1 part by mass or more and 3 parts by mass or less per 100 parts by mass of vinyl chloride resin, and the content ratio is such that, by mass ratio, the adducting compound B is 1 part and the ester compound A is 2 to 4 parts or less. The lubricant comprises methylenebisstearamide and ethylenebisstearamide. The lubricant content is 0.3 parts by mass or more and 0.6 parts by mass or less per 100 parts by mass of vinyl chloride resin, and the content ratio is such that, by mass ratio, ethylenebisstearate is 1 part and methylenebisstearate is more than 0.5 and not more than 5 parts. The aforementioned plasticizer is a phthalate ester plasticizer. The content of the plasticizer is 40 parts by mass or more and 60 parts by mass or less per 100 parts by mass of vinyl chloride resin, characterized in that it is an agricultural vinyl chloride resin film.

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