JPS6234066B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyvinyl chloride film for agricultural use. More specifically, it relates to an agricultural vinyl chloride resin film that has low adhesion between films, has good high-frequency adhesion when applied to greenhouses or tunnels, is resistant to water droplets, and can reduce fog formation in the morning and evening. It is. Agricultural films based on polyvinyl chloride resin are generally used that contain plasticizers for their water drop resistance, toughness, workability, economic efficiency, etc. If this happens, the plasticizer itself, water drop preventive agent, and other additives will migrate to the film surface during use, resulting in the film surface becoming sticky, reducing workability, and dust adhering to the film surface. Easy to do. In addition, in a greenhouse or tunnel covered with a film, moisture in the soil evaporates and aggregates on the surface of the covering film, resulting in cloudy water droplets that deteriorate transparency and cause young buds to form due to falling water droplets. This causes undesirable phenomena such as damage to crops and the development of diseases to crops. Therefore, in order to eliminate such adverse effects, a film or sheet is generally used in which a surfactant such as glycerin fatty acid ester, sorbitan fatty acid ester, etc. is added and kneaded as a so-called antifogging agent to provide a water droplet prevention effect. However, these commonly used surfactants cannot reduce the occurrence of fog inside greenhouses due to changes in outside temperature in the morning and evening. During fog, visibility is poor and work efficiency is reduced, so there is an extremely strong demand from customers to reduce fog. The present inventors have succeeded in improving the shortcomings of conventional agricultural vinyl chloride resin films and obtaining an extremely good film that has a sustained drip-proof effect and can reduce fog generation. In the first place, the condition for the generation of fog is that the water vapor in the house reaches a saturated vapor pressure or higher, and as a means to prevent this, it is necessary to quickly remove the condensed water on the inner surface of the film using a droplet agent. There are two types of fog: fog that occurs in the evening and fog that occurs in the morning.
Fog that forms in the evening, as the outside temperature starts to drop suddenly in the evening, the film temperature also drops, creating a temperature difference between the film surface and the inside of the greenhouse, and the warm air inside the greenhouse comes into contact with the cooler inner surface of the film. It is generated as downdrift fog. Fog that occurs in the morning is caused by the sudden rise in ground temperature due to direct sunlight at sunrise, which creates a temperature difference between the ground surface and the air near the ground surface, which becomes evaporative fog. The thin film of droplets on the inner surface is also heated by direct sunlight, and the advection fog is added to the film. Conventional methods for suppressing the formation of fog have been to color the film to make it less fog-proof, to avoid mulching and watering, to bring ventilation closer to the outside temperature, and to warm the air to make it less foggy. Currently, measures such as raising the saturation point are being taken. The present invention includes, as basic components of vinyl chloride resin, plasticizer, and stabilizer, (a) an ester of sorbitan and higher fatty acid having 1 to 2.5 hydroxyl groups per molecule, and (b) a surfactant with an HLB of 6 or higher. and, the ratio of (a) and (b) is 4:1 to 1:4, and the total number of parts of (a) and (b) is 1 to 3 parts per 100 parts of vinyl chloride resin. This is a vinyl chloride resin film characterized by: The vinyl chloride resin used as the basic component of the present invention includes vinyl chloride homopolymers and copolymers mainly composed of vinyl chloride, such as copolymers of vinyl chloride and vinyl acetate, vinylidene chloride, ethylene, propylene, etc. can give. Examples of plasticizers include phthalate esters, fatty acid esters, epoxies, phosphate esters, and polyglycol esters, and these can be used alone or in combination of two or more. You can also do it. This plasticizer is used in an amount of 30 to 60 parts by weight per 100 parts by weight of the vinyl chloride resin. If the amount is more or less than this, it is not practical as an agricultural film. Stabilizers include inorganic lead salts, metal soaps, organic tin stabilizers, and the like, and these stabilizers may be used alone or in combination. In addition to the above basic ingredients, antioxidants are used as auxiliary agents.
It can be used by including ultraviolet absorbers, organic chelators, pigments, lubricants, bactericides, etc. in the basic ingredients. Examples of isorbitan higher fatty acid esters (with 1 to 2 hydroxyl groups) that are blended into the basic ingredients in the present invention include sorbitan trioleate (HLB 1.8), sorbitan distearate (HLB 2.5), and sorbitan trioleate (HLB 1.8). Examples include stearate type (HLB2.1). These HLBs are all less than 6. The C number of the fatty acid group is 12 or more, preferably 16 or more. ○ Examples of surfactants with HIB6 or higher include sorbitan monofatty acid esters (fatty acid C number 12~
18), polyhydric alcohol fatty acid esters (fatty acid C number 12-18), ethylene oxide (EO) adducts of these esters (including fatty acids with C11 or less but with HLB of 6 or more due to EO addition), aromatic carbon Examples include acid esters.
If a substance smaller than HLB6, such as sorbitan monostearate, is used in combination, droplet flow is poor and impractical. When blending these into the basic ingredients, they may be mixed separately, but (a) and (b) may be mixed in advance in a predetermined ratio (1:
4 to 4:1) and then add vinyl chloride resin.
You may mix 1 to 3 parts by weight per 100 parts by weight.
The mixing ratio of (a) and (b) is particularly preferably 1:1 to 7:3. If the total number of parts (a) and (b) is less than 1 part by weight, the effect will be small, and if it is more than 3 parts by weight, oozing will tend to occur, leading to a decrease in quality. If only (a) is used, the antifogging effect will develop very slowly, and it will be difficult to quickly remove water droplets that aggregate on the film surface, impairing not only water droplet prevention properties but also workability.
Not practical. If only (b) is used, the surfactant will ooze out onto the film surface, causing adverse effects on the film's outer surface such as stickiness and dust adhesion, making it impossible to reduce the amount of fog generated. By blending (a) and (b) in the above ratio, water drop prevention properties and workability will not be reduced, the outer surface of the film will also be good, and the amount of fog generated can be reduced. The agricultural vinyl chloride resin film of the present invention is produced by adding predetermined amounts of (a) and (b) to the mixture of the basic components described above, mixing well, and then forming the film into a film using a calendar roll. The film obtained in this way has low adhesion between the films over a long period of time, has good high-frequency adhesion when applied to greenhouses or tunnels, prevents water droplets from forming, and reduces the amount of fog generated in the morning and evening. It is possible to improve workability with a small amount. Examples 1 to 5, Comparative Examples 1 to 5 Sorbitan trioleate and ethylene oxide (EO) were added to 100 parts by weight (hereinafter abbreviated as parts) of polyvinyl chloride with an average degree of polymerization () 1300 in the proportions shown in Table 1 below. Sorbitan monostearate (HLB15.7) or sorbitan monopalmitate (HLB9.2), 45 parts of dioctyl phthalate, 5 parts of tricresyl phosphate, 1 part of epoxy resin, 4 parts of epoxidized soybean oil, Ba-Zn system 2 parts of a composite stabilizer of
Mix well a composition consisting of 0.3 parts of bisamide;
190℃ using a 28-inch inverted L-shaped calender roll
After being formed into a film with a thickness of 0.1 m/m, it was exposed outdoors in a closed house starting in autumn (October), and the fog formation was evaluated by visual observation, and the results shown in Table 1 were obtained. Further, the high frequency sewing machine processability of the film after 6 months was evaluated, and the results are shown in Table 1.

[Table] In addition, in all of the examples of the present invention shown above and below, the droplet flow properties, anti-fogging properties, bloom properties, etc. were also observed, and the results showed that they were excellent without any problems. Examples 6 to 8, Comparative Examples 6 to 7 = 100 parts of polyvinyl chloride of 1300 and the parts of sorbitan tristearate (HLB2.1), EO-added sorbitan monostearate, or sorbitan monopalmitate shown in Table 2 below A film was formed from a composition consisting of a plasticizer, a stabilizer, and a lubricant that were otherwise the same as in Example 1, and the fog generation was observed and evaluated by outdoor fogging, and the results shown in Table 2 were obtained.

[Table] Examples 9 to 13, Comparative Examples 8 to 10 = 100 parts of 1300 polyvinyl chloride and the number of parts shown in Table 3 below were added to form a film using the same formulation as in Example 1. Exposure was carried out and evaluation was made by visual observation, and the results shown in Table 3 were obtained.

[Table] Comparative Examples 8 and 9 had poor droplet flow properties, and Comparative Example 10 had good droplet flow properties but had severe blooming (a phenomenon in which white powder appears on the surface), and both were unsuitable for practical use. Comparative Examples 11 to 19 = 100 parts of 1300 polyvinyl chloride and sorbitan trioleate, sorbitan tristearate, and sorbitan stearate in the proportions shown in Table 4 below.
A film was formed from the same formulation as in Example 1 using EO addition (HLB15.7) or sorbitan monopalmitate (HLB6.7), and was exposed outdoors and evaluated by visual observation. Got the results.

[Table] Comparative Examples 20-25 = 1.8 PHR of the compounding agent shown in Table 5 was added to 100 parts by weight of 1300 polyvinyl chloride, a film was formed from the same formulation as in Example 1, and exposed outdoors for 3 months. Evaluation was performed by intraocular observation, and the results shown in Table 5 were obtained.

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Claims (1)

[Claims] 1 The basic components of vinyl chloride resin, plasticizers, and stabilizers include ○ esters of isorbitan and higher fatty acids.
Compounds with 1 to 2 hydroxyl groups per molecule and ○ro
A surfactant with an HLB of 6.0 or higher, the ratio of (a) and (b) is 4:1 to 1:4, and the total number of parts of (a) and (b) is based on 100 parts of vinyl chloride resin. An agricultural vinyl chloride resin film containing 1 to 3 parts.