JPH0826200B2 - A method for producing an agricultural film having excellent fog-proof and anti-fog properties - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an agricultural film used for growing off-season crops for agricultural use. More specifically, the present invention relates to an agricultural film that does not generate fog in an agricultural house and exhibits excellent antifogging properties for a long period of time.

[Prior Art] In recent years, crop cultivation has been widely performed in agricultural houses, tunnels and the like using a synthetic resin film for the purpose of early cultivation or off-season cultivation. These synthetic resin films include polyethylene films and polyvinyl chloride films, and polyvinyl chloride films are mainly used.

However, since these synthetic resin films have a hydrophobic film surface, if they are used as they are, the water vapor evaporated from the surface of the agricultural house or the tunnel or the crop body will condense on the film surface and adhere as water droplets. The film surface will be significantly fogged without showing.

As a result, the penetration of sunlight is poor, and the temperature rise in the heat-insulating greenhouse is reduced, which significantly hinders the growth of crops.

In order to solve these problems, an agricultural film currently used is added with an antifogging agent containing a surfactant as a main component.

The surface of the agricultural film to which such an antifogging agent is added becomes hydrophilic, and the attached water droplets show a wetting phenomenon and immediately spread to the film surface and flow down, so that the film surface is kept transparent. .

However, the above-mentioned agricultural film to which the anti-fogging agent is added has good solar ray transmission and an excellent temperature raising effect, but has a drawback that fog is easily generated in the house. If fog occurs in the house, it may cause leaves, flowers, stems, etc. of the cultivated crops to wet and cause diseases such as gray mold and vine blight, which may reduce the yield of crops. It has a very poor see-through and causes disadvantages such as lowering work efficiency.

This fog phenomenon is often observed in the late autumn and winter seasons when the outside temperature is low in the morning and evening.

The direct cause of such fog generation in the agricultural house is that the steam inside the house reaches a saturated vapor pressure or higher due to the temperature difference inside and outside the house. That is, in the early fog, the water vapor evaporated from the ground surface in the house comes into contact with the cold air above the house and condenses into water droplets. In the evening fog, water vapor near saturation in the house condenses as the temperature above the house decreases, forming water droplets and forming fog. Furthermore, some factors that promote the generation of fog and the generation of fog will be discussed.

 One is the presence of condensation nuclei in the house.

It is assumed that the water vapor rising from the surface of the house promotes condensation (generation of fog) with dust inside the house as a nucleus. This depends on the location of the house and the environment of the house. It is also considered that the degree of hydrophilicity of the film surface in the house also influences. That is, it is considered that the following three phenomena are constantly occurring on the film surface.

One is the flow of water condensed on the film surface due to the collision of water vapor evaporated from the house ground surface and crops,
One is the bounce of steam that collided into the house,
One is the re-evaporation phenomenon of water flowing down the film surface inside the house.

The balance of these phenomena is considered to be largely related to the degree of hydrophilicity of the film surface, and is presumed to be an important factor that determines the extent of fog generation.

Conventionally, various methods such as a method of reducing the temperature difference between the inside and the outside of the house by ventilation, a method of raising the saturated steam pressure by heating and a method of using a colored film have been taken as methods for suppressing the generation of the above-mentioned fog. However, neither was a sufficient method.

Further, the method of adding an organic siloxane-based surfactant described in JP-A-55-91663 and JP-A-57-14464
Although a method of adding a kind of fluorine-based surfactant described in Japanese Patent No. 8 has been proposed, none of them can completely suppress the generation of fog, or even if it has a fog-preventing effect, it can be used for agriculture. There are still some drawbacks such as a decrease in the effect of keeping the antifogging property for a long period which is basically required for the film.

[Problems to be Solved by the Invention] The present inventors prevent the generation of fog in the above-mentioned agricultural greenhouse (fog-preventing property) and produce an agricultural film exhibiting excellent anti-fog property for a long period of time. As a result of intensive research aimed at that, the present invention has been achieved.

[Means for Solving Problems] In the present invention, a fluorine compound represented by the following general formula [I] and a sorbitan fatty acid ester [II] are combined with [I]: [II] =
Weight ratio of 50:50 to 10:90 with respect to vinyl chloride resin 1 to 5
The present invention relates to a method for producing an agricultural film having excellent anti-fog properties and anti-fog properties, which is characterized in that it is added by weight%.

General formula [I]: (Rf is a perfluoroalkyl group having 6 to 10 carbon atoms, n is 5
Indicates an integer of ~ 30. ) The present invention will be described in detail below.

Examples of the vinyl chloride resin used in the present invention include vinyl chloride homopolymer, vinyl chloride and vinyl acetate and its esters, acrylic acid and its esters, methacrylic acid and its esters, ethylene, propylene, vinylidene chloride, maleic acid and fumaric acid. A copolymer such as an acid is included, and among them, vinyl chloride resin is preferable.

The fluorine compound represented by the above general formula [I] used in the present invention is a ring-opening addition reaction of 2 mol of perfluoroalkylethanol and 1 mol of diglycidyl ether of polyethylene glycol having the following structure. It is an α, ω diperfluoroalkyl compound obtained by

In the above general formula [I], Rf is preferably a perfluoroalkyl group having 6 to 10 carbon atoms and n is preferably in the range of 8 to 20 from the viewpoint of antifogging effect. Compounds in which n is less than 5 or more than 30 are not preferable because both fog resistance and antifogging property are poor.

The sorbitan fatty acid ester [II] used in the present invention is obtained by dehydrating 1 mol of sorbit and 1 to 1.5 mol of higher fatty acid having 12 to 18 carbon atoms by a conventional method. Examples of the higher fatty acid of 18 include coconut fatty acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and the like, but palmitic acid and stearic acid are preferable for their effect.

The mol number of higher fatty acid is 1 to 1 mol of sorbit
It is in the range of 1.5 mol, and if it exceeds 1.5 mol, the antifogging property becomes poor, which is not preferable.

When the compound represented by the general formula [I] and the sorbitan fatty acid ester [II] in the present invention are added respectively to a vinyl chloride resin, the compound of the general formula [I] has both antifogging property and antifog property. In addition, the sorbitan fatty acid ester [II] exhibits an antifogging effect but is not fog-proof and neither is practical.

However, by using the compound of the general formula [I] and the specific sorbitan fatty acid ester [II] together in a specific ratio, an agricultural film exhibiting excellent antifogging and antifog properties, which is the gist of the present invention, can be obtained. It can be manufactured.

The reason why the compound of the general formula [I] and the specific sorbitan fatty acid ester [II] are used in a specific ratio in combination to exhibit synergistically excellent fog resistance and antifogging property has not yet been clarified, but the present invention Based on the knowledge gained from many years of research on anti-fogging agents for agricultural films, the inventors speculate as follows. That is, in view of the above-mentioned fog generation mechanism, in order to suppress the generation of fog, it is essential to keep the water vapor concentration above the inside of the house at a saturated vapor pressure or less at all times. The point is to quickly condense, diffuse and flow down on the film surface.

The factor that determines the speed from the collision of water vapor to the flow down is the degree of expansion of water droplets condensed on the film surface.

This degree is affected by the state of the antifogging layer formed on the film surface. By using the α, ω diperfluoroalkyl compound of the general formula [I] having a polyoxyethylene chain, which is a hydrophilic group, in the central part of the molecule and a specific sorbitan fatty acid ester in combination, good prevention of expansion of the above water droplets can be achieved. It is presumed that a cloudy layer is formed.

Further, it is speculated that the cause of the excellent antifogging sustainability may be an additive effect of the combined use of the compound of the general formula [I] and the sorbitan fatty acid ester [II].

The total addition amount of the compound of the general formula [I] and the sorbitan fatty acid ester [II] to the vinyl chloride resin is 1
The addition of more than 5% by weight is preferable, and the addition of more than 5% by weight cannot improve the performance so much, and is economically disadvantageous.

The agricultural film of the present invention is, as is known, a soft vinyl chloride and is usually 30 to 70 per 100 parts by weight of a vinyl chloride resin.
Parts by weight of a plasticizer are appropriately used, and stabilizers, lubricants, ultraviolet absorbers, antioxidants, colorants and the like are used as necessary. Thus, the vinyl chloride resin composition containing the above components is formed into a film by a known method such as calendering or melt extrusion.

[Effects of the Invention] The present invention provides an agricultural film having both excellent anti-fog properties and anti-fog properties by blending and using a specific fluorine compound and a specific sorbitan fatty acid ester in a specific ratio. . That is, by using the agricultural film of the present invention, it is possible to completely prevent the generation of fog, which is often observed in the house from late autumn to winter, and to eliminate the above-mentioned harmful effects caused by fog. At the same time, the agricultural film of the present invention exhibits excellent anti-fogging properties for a long period of time, and is therefore very effective for facility cultivation such as off-season cultivation of crops.

[Examples] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 100 parts by weight of vinyl chloride resin (degree of polymerization: 1100), 45 parts by weight of dioctyl phthalate, 2 parts by weight of epoxidized soybean oil, 5 parts by weight of tricresyl phosphate, 1 part by weight of Ba-Zn based metal soap, methylene. 0.5 parts by weight of bisstearylamide and 2 parts by weight of the composition A of the present invention shown below were mixed and a 100 micron film was prepared using a calendar roll.

The composition A of the present invention is a composition comprising the following [I] and [II].

Sorbitan palmitic acid (1.2 mol) ester [II]
・ ・ ・ 80 parts by weight This film was attached to a frame assembled on an outdoor temperature-controllable water tank to create a greenhouse for experiments. The following method was used to observe the generation of fog and evaluate the antifogging property.

Method of observing fog The test started in late October. During the morning and evening time when the temperature dropped, the water temperature of the water tank installed in the experimental greenhouse was set to 40 ° C and the fog generation state in the greenhouse was observed for about 2 hours. The water tank was left alone except for the fog observation time. This observation 3
I went regularly until the month. The degree of fog generation is expressed by the following criteria.

◎ ・ ・ ・ No fog is observed at all.

○: A slight amount of fog is observed.

△: Generation of fog is recognized.

×: Significant fog was observed.

Evaluation method of anti-fog property In parallel with the observation of fog, the anti-fog property of the inner surface of the film stretched in the experimental greenhouse was observed for 10 months. The antifogging property was evaluated according to the following criteria.

◎ ・ ・ ・ ・ ・ No water droplets are observed.

○ ・ ・ ・ Slightly adhering water droplets.

△: A state in which water droplets are adhering.

×: A state in which a considerable amount of water droplets is observed.

XX: Water droplets are observed on the entire surface.

Examples 2 to 5 In the same manner as in Example 1, the following compositions B to E of the present invention were used.
Was added to obtain a film and Examples 2 to 5 were obtained. The evaluation results are summarized in Table 1.

Composition B: Sorbitan stearic acid (1.2 mol) ester [II]
..... 90 parts by weight Composition C: Sorbitan stearic acid (1.3 mol) ester [II]
........... 40 parts by weight sorbitan palmitic acid (1.3 mol) ester [II]
........... 20 parts by weight Composition D: Sorbitan palmitic acid (1.2 mol) ester [II]
..... 90 parts by weight Composition E: Sorbitan lauric acid (1.5 mol) ester [II]
・ ・ ・ ・ ・ ・ ・ ・ 10 parts by weight Sorbitan palmitic acid (1.3 mol) ester [II]
..... 70 parts by weight Comparative Example 1 A film in which the amount of the composition A added was 0.5 parts by weight was prepared in the same manner as in Example 1 to obtain Comparative Example 1.

Comparative Example 2 In the same manner as in Example 1, a film was prepared in which the composition B ′ in which the mixing ratio of the fluorine compound [I] and the sorbitan fatty acid ester [II] according to the present invention was outside the range of the present invention was prepared. Comparative example 2 was obtained.

Composition B ' Sorbitan stearic acid (1.2 mol) ester [II]
... 95 parts by weight Comparative Example 3 In the same manner as in Example 1, the compounding ratio of the fluorine compound [I] and the sorbitan fatty acid ester [II] according to the present invention was out of the range of the present invention. Comparative Example 3 was obtained by making a film to which a certain composition E'was added.

Composition E ' Sorbitan lauric acid (1.5 mol) ester [II]
・ ・ ・ ・ ・ ・ ・ ・ 5 parts by weight Sorbitan palmitic acid (1.3 mol) ester [II]
25 parts by weight Comparative Example 4 to Comparative Example 6 Composition F other than the present invention described below in the same manner as in Example 1
-Comparative Example 4-Comparative Example 6 were obtained by making a film to which the composition H was added.

Composition F Sorbitan palmitic acid (1.2 mol) ester [II]
..... 80 parts by weight Composition G Sorbitan stearic acid (1.1 mol) ester [II]
..... 75 parts by weight Composition H Sorbitan palmitic acid (2 mol) ester [II]
70 parts by weight Table 1 shows the results of Examples and Comparative Examples, but it is clear that the Examples of the present invention exhibit superior effects as compared with the Comparative Examples.

Claims (2)

[Claims] 1. A fluorine compound represented by the following general formula [I] and a sorbitan fatty acid ester [II] are combined with [I]: [I
I] = 50: 50 to 10:90 in a weight ratio of 1 to 5% by weight with respect to the vinyl chloride resin, a method for producing an agricultural film having excellent fog-proof and anti-fog properties. General formula [I]: (Rf is a perfluoroalkyl group having 6 to 10 carbon atoms, n is 5
Indicates an integer of ~ 30. ) 2. A sorbitan fatty acid ester is sorbit 1
The method for producing an agricultural film according to claim (1), which is obtained by reacting 1 to 1.5 mol of higher fatty acid having 12 to 18 carbon atoms with mol.