JPH02279733A - Agricultural film and its production - Google Patents

Abstract

PURPOSE:To obtain a non-dripped agricultural film inexpensively in good workability by coating a thermoplastic resin film containing a specified amount of a fine inorganic powder with a surface-coating type non-dripping agent based on an inorganic hydrophilic colloidal substance and a hydrophilic organic compound. CONSTITUTION:A fine inorganic powder (e.g. hydrotalcite compound or magnesium hydroxide) is added to a thermoplastic resin such as a branched low-density polyethylene, an ethylene/vinyl acetate copolymer or a linear low-density polyethylene, and the obtained mixture is formed into a film to produce a thermoplastic resin film containing 0.1 to 15wt.% inorganic powder. The obtained film is coated with a surface-coating type non-dripping agent based on an inorganic hydrophilic colloidal substances (e.g. colloidal silica) and a hydrophilic organic compound (e.g. polyoxyethylene oleate) to obtain an agricultural film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a /3 industrial film and a method for producing the same.

[Conventional technology]

Agricultural films used for greenhouse and tunnel cultivation include polyvinyl chloride (PVC), branched low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), and linear low-density polyethylene (LLDPE).
) etc. as a base resin and has a thickness of approximately 30 to 200 μm.

The inside of a house or tunnel covered with these films is saturated with water vapor transpiring from the ground or plants, so this water vapor condenses on the cooled inner surface of the film and adheres as water droplets. When water droplets adhere, the incident sunlight is significantly reduced due to diffuse reflection, and the water droplets fall and wet the crops, causing frequent disease.

For this reason, films are generally subjected to so-called water drop prevention (hereinafter referred to as "dropless") treatment to turn adhering water droplets into a water film. Currently, by using a drip-free film that has undergone this drip-free treatment, it is possible to allow as much sunlight as possible to pass into greenhouses and tunnels, raise the soil and air temperature inside, and promote photosynthesis, promoting healthy crop growth. We are trying to promote this condition and suppress the occurrence of diseases.

Conventional methods for dropless treatment include the dropless agent kneading method, in which a dropless agent is kneaded into a base resin and formed into a film, and the coating method, in which a dropless agent is coated after film formation. be.

Among these, the dropless film obtained by the coating method has not been put to practical use as a flexible plastic film for agricultural use due to its performance.

Even if a soft plastic film is coated with surfactants and hydrophilic polymer materials that have been used as dropless agents, their surface energy is low, resulting in (1) poor wettability and repellency; Unable to apply evenly
(2) Due to poor adhesion, the droplet-free life is very short as it is washed away by attached water droplets. (3) There are many problems with blocking of the film due to stiffness due to the non-droplet agent.
This is because it is not possible to obtain an agricultural film that maintains its drip-free properties for several months to one year or more.

However, in recent years, a new type of spray-on type non-drop agent has been developed. This dropless agent is mainly composed of an inorganic hydrophilic colloid substance and a hydrophilic organic compound.
-45432, Special Publication No. 63-45717, Special Publication No. 63
This is a compound shown in No. 4-2158.

Examples of inorganic hydrophilic colloid materials include colloidal silica, colloidal alumina, colloidal Fe(OH)
, Colloidal S n (OH) 4 .

Colloidal TiO2, Colloidal B a S O4
and colloidal lithium silicate. Particularly preferred materials are colloidal silica and colloidal alumina.

Examples of hydrophilic organic compounds include various surfactants (nonionic, anionic, and cationic) and hydroxyl group-containing vinyl monomer components, and acid group-containing vinyl monomer components of 0.1 to Examples include a copolymer containing 40% by weight or a partially or completely neutralized product thereof, and a sulfonic acid group-containing polyester resin.

This type of spray-on type non-drop agent has significantly improved wettability and adhesion, and a film coated with it can have a drop-free life of six months to one year or more.

(Problems to be Solved by the Invention 1) However, basically, the wettability and adhesion to substances with low surface energy, such as soft plastic films used for agricultural purposes, are insufficient. Especially polyolefin films with low polarity, such as LDPE, EVA,
This tendency is very strong in LLDPE films.

Therefore, for example, when a soft plastic film is spread on a house and then coated with a non-droplet agent by spraying it with a power sprayer or the like, a large amount of the non-droplet agent is required, which increases the cost. It also takes longer to spray. Furthermore, uneven spraying occurs on the film, causing problems such as impairing the drip-free effect of the house. Also, when coating film with a coater, a large amount of coating liquid is consumed.

However, the coating speed cannot be increased, leading to problems such as increased manufacturing costs.

In order to solve these problems, methods have recently been adopted to improve the wettability of the surface by introducing polar groups into the film surface through chemical changes such as corona discharge treatment, ie, oxidation. However, in this method, the stronger the treatment to improve wettability, the more the film surface and even the inside become oxidized, and the weather resistance of the film decreases. Such a decrease in weather resistance is a fatal problem for A and I films. Therefore, this method cannot be adopted.

Another method is to modify the base resin or film surface by chemical reaction, that is, introduce polar groups (hydrophilic groups, etc.), but at present it leads to a significant increase in cost and is not suitable for use in agricultural films. It's difficult.

This invention was made in order to solve such conventional problems, and it is an inexpensive agricultural product that has excellent coating properties of the non-droplet agent on the base film and non-droplet properties after application of the non-droplet agent. The purpose is to provide a film and its manufacturing method.

[Means to solve the problem]

The agricultural film provided by this invention contains zero inorganic fine powder.
A thermoplastic resin film containing 1 to 15% by weight is coated with a surface-applied non-droplet agent containing an inorganic hydrophilic colloid substance and a hydrophilic organic compound as main components.

Furthermore, the method for producing an agricultural film provided by the present invention includes coating a thermoplastic resin film with a surface-applied dropless agent containing an inorganic hydrophilic colloid substance and a hydrophilic organic compound as main components. This is a method in which the film contains inorganic fine powder in advance.

The thermoplastic resin mentioned here is LDPE.

Polyolefins such as EVA, LLDPE, and PvC
etc. can be mentioned.

The inorganic fine powders include lithium, sodium, potassium, magnesium, calcium, lead, and aluminum. Oxides, hydroxides, carbonates of metals such as silicon and titanium,
These include sulfates, phosphate borates, silicates, aluminates, and aluminosilicates. Among these, examples of oxides include magnesium oxide, calcium oxide, aluminum oxide, silicon oxide, titanium oxide, etc., and examples of hydroxides include:
Lithium hydroxide, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, etc. Carbonates include magnesium carbonate, calcium carbonate, etc. Sulfates include potassium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, aluminum sulfate, etc. Phosphates include lithium phosphate, sodium phosphate, potassium phosphate, calcium phosphate, etc.
As borates, as disilicates such as sodium borate,
Magnesium silicate, calcium silicate, aluminum silicate, titanium silicate, etc.; examples of aluminate include sodium aluminate, potassium aluminate, calcium aluminate, etc.; Potassium itate, calcium aluminosilicate, etc. may be mentioned, and complex salts thereof include, for example, base+1 complex salts represented by hydrotalcites represented by the following formula.

Ml-x A flX (O)l ) 2 Ax /
n' m H20, M is a divalent metal ion selected from the group consisting of magnesium, calcium and zinc, A is an n-valent anion, and 0<x<0.5. O≦
m≦2.

Among these inorganic fine powders, those having hydroxyl groups, particularly hydrotalcites, are preferred.

The addition Ill of the inorganic fine powder to the thermoplastic resin film is from 01 to 15% by weight, preferably from 05 to 10% by weight. If the amount is less than 0.1% ffiI, the improvement effect will be small, and if it is 15fflff1% [4], the strength and transparency of the film will be impaired. The smaller the particle size of the powder is, the more uniformly it will be dispersed, so the improvement effect will be greater. For example, it is about 0.5 to 5μ. On the other hand, if the size is about 5 to 10 microns, the strength and transparency of the film will decrease, although it depends on the amount added.

Among inorganic fine powders, hydrotalcites can be set to have a refractive index in the range of about 1.50 to 155, and can be matched to the refractive index of PVC film or LDPE film, so it does not impair the transparency of the film. It has the advantage of having less

As shown in FIG. 1, the thermoplastic resin film F is usually a mixture of inorganic fine powders uniformly dispersed throughout the film, and a coating layer of a dropless agent is provided thereon. However, since it is difficult to completely disperse and mix inorganic fine powder, the amount added is approximately 2 to 3
When the amount exceeds % by weight, fine irregularities are generated on the film surface and light is diffusely reflected, which may reduce the transparency of the film.

As a countermeasure for this, as shown in Figure 2, the thermoplastic resin film F has a three-layer structure, the middle layer m mainly contains inorganic fine powder, and the layers on both sides are made of a transparent film containing almost no inorganic fine powder. It is preferable to use layers a and b.

Further, as shown in FIG. 3, the thermoplastic resin film F may have a two-layer structure. That is, the middle layer m in FIG.
and a transparent layer.

The thickness of the transparent layer a in contact with the coating layer of the dropless agent in FIG. 2 must be 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less. If it exceeds 100μ, the effect of improving wettability and adhesiveness will be almost completely lost. The reason for this is that, although the exact mechanism of the improvement effect of the inorganic fine powder has not been fully elucidated, it is presumed that the electrostatic interaction of the inorganic fine powder weakens the charging property of the film. Therefore, even if the transparent layer a is interposed between the coating layer of the dropless agent and the intermediate WJm containing the inorganic fine powder, as long as the thickness is 100 μm or less, the effect of improving wettability and adhesion is not effective. This seems to be acceptable. In addition, in the transparent layers a and b, the amount of inorganic fine powder within a range that does not impair the transparency of the film, for example 0.1 to
There is no problem even if it is added in an amount of 2% by weight.

The method for coating the thermoplastic resin film with the dropless agent may be any of various roll printing methods, spraying methods, and spraying methods. In addition, coating can be performed by inline coating after forming the film, outline coating during the unwinding process after film forming and winding, or spray coating on the inner surface of the film after it is stretched. .

(Function) In this invention, since the thermoplastic resin film that is the base film is mixed with inorganic fine powder in advance, it is thought that the electrostatic interaction caused by the fine powder significantly changes the charging characteristics of the film surface. .

Therefore, the wettability and adhesion of the surface-applied non-droplet agent to the thermoplastic resin film are improved, and therefore, the applicability of the dropless agent is also improved. In other words, a small amount of dropless agent can be applied widely, evenly, and evenly in a short time.
The cost is also low. Furthermore, since the dropless agent is evenly and uniformly applied, the dropless effect is not impaired.

[Example] (Example 1) The following base film was spread over a vibe house with a width of 5.4 m, a height of 2.8 m, and a length of 50 m, and the inside surface was coated with the following non-droplet agent by spraying it with a power sprayer A. Then, the applicability and non-dripability of the dropless agent were evaluated.

(1) Base film: LDPE (Mll, O, SGo, 920) with hydrotalcite compounds (Kyowa Scientific ■ Alkamizer, (
M = Mg, A-CO3.

X=0.3. m=0.5) and 0.5% by weight of a hindered amine compound (Tinuvin 622, manufactured by Ciba Geigy).

(2) Dropless agent: (a) Colloidal silicania 0% by weight (Catalyst Kasei Co., Ltd. Cataloid 5t-350) (b) Silane derivative: 5% by weight (γ-ureidopropyltriethoxysilane) (C) Nonionic surfactant Agent: 25% by weight (polyoxyethylene (7 mol) oleic acid ester) A dropless product with an active ingredient concentration of 2% by weight obtained by adding water to the active ingredients (a) to (C) above and stirring and mixing. agent.

On the other hand, for comparison, LDPE (ME 1.0, SG
The above-mentioned dropless agent was coated on a film having a thickness of 100 μm based on the film 920) in the same manner as in Example 1, and hereinafter referred to as [the film of Comparative Example 1]. ), coating properties and non-droplet properties were evaluated.

As a result of the evaluation, the improvement effect was most clearly understood in the applicability. That is, in the "film of Comparative Example 1", 1
Although it was possible to coat only about 2 m'' of the base film with Little Dropless Agent, in the case of the ``film of Example 1'', it was possible to coat about 6 doors, three times as long. In addition, the time required for spraying was approximately 45 minutes for the film of Comparative Example 1, whereas the time required for the spraying process was approximately 45 minutes for the film of Example 1.
Well, I finished it in about 15 minutes, which is one-third of the way.

When the drop-free property after application was judged with the naked eye, uneven coating was observed everywhere in the film of Comparative Example 1, and there were some parts with poor drop-free property, but in the case of the film of Example 1 The water droplets were flowing down as a uniform water film.

(Example 2) The following base film was spread on a pipe house in the same manner as in Example 1, and the inner surface thereof was coated with the above-mentioned dripless agent in the same manner as in Example 1, and the applicability and dripless property of the dripless agent were evaluated. did.

(1) Base film: A film with a thickness of 100 μm that was rttm-shielded in the same manner as in Example 1, except that magnesium hydroxide was used instead of the hydrotalcite compound.

As a result of the evaluation, the coating area of the "film of Example 2" was approximately 4
rn'', and the time required for this was approximately 25 minutes.

In addition, although the drop-free property is slightly inferior compared to Example 1,
The water droplets flowed down as a nearly uniform water film.

(Examples 3 to 6) The following base film was spread on a pipe house in the same manner as in Example 1, and the inner surface thereof was coated with the above-mentioned non-droplet agent in the same manner as in Example 1, and the coating properties and non-droplet properties of the non-droplet agent were evaluated. was evaluated.

<1) Base film: A film 1 having a three-layer structure shown in FIG. 2, which was formed by blending a % by weight of the same hydrotalcite compound used in Example 1 only in the middle layer m. ．． However, the thicknesses of the intermediate layer m and the transparent layers a and b were as shown in Table 1.

Table 1 The results of the evaluation are shown in Table 2.

Table 2 As is clear from Table 2, between the thermoplastic resin film containing the inorganic fine powder and the coating layer of the dropless agent,
Even when a transparent layer is interposed, as long as the thickness of the transparent layer is 1OOμ or less, the adhesiveness of the dripless agent coating layer and the effect of imparting dripless properties to the resin film can be achieved. I understand.

(Example 7) The following non-droplet agent was coated on the base film (width: 550 aa+) of Example 1 at various speeds using a gravure coater with a roll width of 600a+s, and the coating properties of the dropless agent at each speed and the non-droplet-free agent were evaluated. The droplet properties were evaluated. Drop-free properties were evaluated by setting up a small spreading stand in the field and spreading the film on it. Note that the dropless agent was dried with hot air.

(Dropless agent) A dropless agent obtained by mixing the following active ingredients (a) to (d) in their respective proportions.

(a) Polymer-A: 100 parts by weight (b) Alcohol-dispersed colloidal silica (methanol silica manufactured by Nissan Chemical ■): 35 parts by weight (C) Polyoxyethylene lauryl ether (surfactant): 15 parts by weight (d) Methanol: 4501]! ffi part However, polymer-8 in the above active ingredients is the following components (a) to (d)
This is a compound obtained by reacting the mixed solution at 60°C for 5 hours and neutralizing it with a 20% aqueous N8 solution.

(a) 2- and droxyethyl acrylate: 99 parts by weight (b) Acrylic acid: 1 part by weight (e) Azobisisobutyronitrile (reaction catalyst): 0.
5 parts by weight (d) Methanol = 200 parts by weight On the other hand, for comparison, LDPE (Ml 1.05SG
In the same manner as in Example 7, the non-droplet agent of Example F was applied to a 100μ thick film based on
The following is the film of Comparative Example 2.
), the applicability and drip-free properties of the drop-free agent at each speed were evaluated.

The coating properties were visually observed during coating, and the results are shown in Table 3. In addition, the drip-free property was confirmed by creating a film sample on November 26, 1988, and expanding it on December 3, 1988.
Table 4 shows the results of visual observation on the 15th day of the month.

Table 3 Table 4 Table 31 As is clear from Table 4, the "film of Comparative Example 2" can only achieve a coating speed of 5 to 10 m/min, while the "film of Example 7" can achieve a coating speed of 40 to 50 m/min.
It can be seen that coating can be done in minutes.

(Effects of the Invention) As explained above, according to the present invention, since it has the above-described structure, it is excellent in the applicability of the dropless agent to the base film and the dropless property after application of the dropless agent, Moreover, an inexpensive agricultural film and a method for producing the same can be obtained.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are cross-sectional views of a film for a-industry use according to an embodiment of the present invention. F... Thermoplastic resin film D --- Non-droplet coating layer a, b...- Transparent layer m --- Intermediate layer Fig. 1 Fig. 2 Fig. 3

Claims (4)

[Claims] (1) For agricultural use, a thermoplastic resin film containing 0.1 to 15% by weight of inorganic fine powder is coated with a surface-applied non-drop agent containing an inorganic hydrophilic colloid substance and a hydrophilic organic compound as main components. film. (2) Thermoplastic resin is LDPE, EVA, LLDPE
The agricultural film according to claim 1, which is a polyolefin such as. (3) When coating a thermoplastic resin film with a surface-applied dropless agent containing an inorganic hydrophilic colloid substance and a hydrophilic organic compound as main components, the thermoplastic resin film must contain inorganic fine powder in advance. A method for producing an agricultural film characterized by: (4) Thermoplastic resin is LDPE, EVA, LLDPE
The method for producing an agricultural film according to claim 3, which is a polyolefin such as.