JPH04264140A - Agricultural film and its manufacturing method - Google Patents

Abstract

PURPOSE:To provide an inexpensive agricultural film excellent in coatability with a dripproofing agent and dripproofness after being coated, and a process for producing the same. CONSTITUTION:An agricultural film prepared by coating a thermoplastic resin film E1 containing an ethylene copolymer having a hindered amine as the side chain with a surface-coating type dripproofing agent D based on an inorganic hydrophilic colloidal substance and a hydrophilic organic compound. A process for producing the agricultural film comprising coating the thermoplastic resin film E1 with the dripproofing agent D after adding the ethylene copolymer to the thermoplastic film E1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an agricultural film and a method for producing the same.

0002

[Prior Art] Agricultural films used for greenhouse and tunnel cultivation include polyvinyl chloride (PVC), branched low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), linear low-density polyethylene(
Thickness of approximately 30 to 200 mm using base resin such as LLDPE)
The main material is μ soft plastic film.

The interior 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, they not only significantly reduce incident sunlight due to their diffuse reflection, but also
In addition, water droplets fall and wet the crops, causing frequent diseases.

[0004] For this reason, films are generally subjected to a so-called water drop prevention (hereinafter referred to as droplet prevention) treatment to turn adhering water droplets into a water film. Nowadays, by using a droplet film that has been treated with droplets, 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, thereby promoting healthy crop growth. We are trying to promote this condition and suppress the occurrence of diseases.

[0005] Conventional droplet treatment methods include a droplet mixing method in which a droplet agent is kneaded into a base resin and formed into a film, and a coating method in which a droplet agent is coated after film formation. There is a law. Among these, the droplet-forming 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.

[0006] This is due to the following reasons. In other words, even if a soft plastic film is coated with a surfactant or hydrophilic polymer substance that has been used as a droplet agent, its surface energy is low, so (1) it has poor leakage, causes a repelling phenomenon, and is not uniformly coated. (2)
Due to poor adhesion, the droplet life is very short as it is washed away by attached water droplets, and (3) there are many blocking problems of the film due to the stickiness caused by the droplet agent. This is because a suitable agricultural film cannot be obtained, and in many cases, the droplet flow property is only for about one month.

However, in recent years, a new type of coating type droplet has been developed. This droplet agent is mainly composed of an inorganic hydrophilic colloid substance and a hydrophilic organic compound.
This is a compound disclosed in Japanese Patent Publication No. 64-2158.

Examples of inorganic hydrophilic colloids include colloidal silica, colloidal alumina, and colloidal F.
Examples thereof include e(OH)2, colloidal Sn(OH)4, colloidal TiO2, colloidal BaSO4, 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, with zero acid group-containing vinyl monomer components. Examples include copolymers containing .1 to 40% by weight or partially or completely neutralized products thereof, and polyester resins containing sulfonic acid groups.

[0010] This type of coating type droplet has greatly improved wettability and adhesion, and the life of the droplet properties of a film coated with it can be about six months to one year.

[0011]

[Problems to be Solved by the Invention] However, basically, the wettability and adhesion to materials with low surface energy, such as soft plastic films used for agricultural purposes, are insufficient. This tendency is particularly strong in polyolefin films with low polarity, such as LDPE, EVA, and LLDPE films.

[0012] Therefore, for example, when a soft plastic film is spread on a house and then coated with a droplet agent by spraying it with a power sprayer, a large amount of droplet agent is required;
This will increase costs. Also, the spraying process takes longer. Furthermore, uneven spraying occurs on the film, causing problems such as impairing the droplet effect of the house. Furthermore, when coating a film with a coater or the like, there arise problems such as consuming a large amount of coating liquid, making it impossible to increase the coating speed, and increasing manufacturing costs. moreover,
The applied droplet agent peels off due to the falling of adhering water droplets, and it is impossible to maintain a stable droplet effect for more than one year or several years.

[0013] Another method is to modify the base resin or film surface by chemical change, that is, introduce polar groups (hydrophilic groups, etc.), but at present it leads to a significant increase in cost and is not suitable for agricultural films. It is difficult to apply it to

[0014] The present invention was made in order to solve these conventional problems, and has excellent coating properties of the droplet agent on the base film and droplet flow after application of the droplet agent, and is inexpensive. The purpose of the present invention is to provide agricultural films and methods for producing the same.

[0015]

[Means for Solving the Problems] The agricultural film provided by the present invention consists of a thermoplastic resin film containing an ethylene copolymer having a hindered amine in its side chain, and an inorganic hydrophilic colloid substance and a hydrophilic organic compound as main components. It is coated with a surface-applied droplet as a component.

[0016] Furthermore, the method for producing an agricultural film provided by the present invention involves coating a thermoplastic resin film with a surface-applied droplet containing an inorganic hydrophilic colloid substance and a hydrophilic organic compound as main components. This is a method in which a thermoplastic resin film contains in advance an ethylene copolymer having a hindered amine in its side chain.

[0017] As the thermoplastic resin referred to herein, LDP
Polyolefins such as E, EVA, and LLDPE are suitable. Furthermore, as the ethylene copolymer having a hindered amine in its side chain, a copolymer of ethylene and a vinyl compound represented by the following general formula is suitable.

[0018]

[Chemical formula 3]

(In the formula, R1 and R2 represent a hydrogen atom or a methyl group, and R3 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, respectively.) Vinyl compounds of the above general formula are known and copolymerized. The combination can also be synthesized by a known method, for example, the method described in Japanese Patent Publication No. 47-8539 and Japanese Patent Application Laid-open No. 48-65180. Representative examples of vinyl compounds having the above general formula are as follows.

4-Acryloyloxy-2,2,6,6
-Tetramethylpiperidine 4-acryloyloxy-1,2,2,6,6-pentamethylpiperidine 4-acryloyloxy-1-ethyl-2,2,6,6
-tetramethylpiperidine 4-acryloyloxy-1-propyl-2,2,6,
6-tetramethylpiperidine 4-acryloyloxy-1-butyl-2,2,6,6
-Tetramethylpiperidine 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 4-methacryloyloxy-1,2,2,6,6-pentamethylpiperidine 4-methacryloyloxy-1-ethyl-2,2 ,6,
6-tetramethylpiperidine 4-methacryloyloxy-1-butyl-2,2,6,
6-tetramethylpiperidine 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine 4-crotonoyloxy-1-propyl-2,2,6,
6-Tetramethylpiperidine It should be noted that these ethylene-based copolymers having hindered amines in their side chains also act as weathering stabilizers, and are mainly effective in improving the weathering resistance of polyolefin films, as disclosed in JP-A-57-180616. This method is already known from Japanese Patent Publication No. 63-2963.

[0021] In this invention, "thermoplastic resin containing an ethylene copolymer having a hindered amine in the side chain" refers to a thermoplastic resin containing an ethylene copolymer copolymerized with the vinyl compound at a high concentration. This refers to cases in which a vinyl compound is directly copolymerized with a thermoplastic resin such as LDPE, EVA, etc. at a predetermined concentration and used alone.

[0022] The proportion of vinyl compound units is 0.05 to 3.0 as vinyl compound units in the thermoplastic resin film.
It is preferably 0.1 to 1.0% by weight. If it is less than 0.05% by weight, the effect of improving droplet persistence will be small, and if it exceeds 3.0% by weight, it will have an adverse effect on the droplet persistence in the initial stage and the effect of improving droplet persistence will be saturated.

The ethylene copolymer may be contained uniformly in a single layer film, or may be concentrated and contained in the outermost layer of a multilayer film. The higher the content, the greater the effect of improving droplet persistence, so it is preferable to have a multilayer structure in which it is concentrated in the outermost layer in terms of effectiveness and economy.

In the case of a multilayer structure, a droplet is applied to the surface of the outermost layer containing concentrated ethylene copolymer. However, layers other than the outermost layer may also contain an appropriate amount if necessary. When containing an ethylene copolymer,
Various stabilizers, lubricants, colorants, heat insulating agents (e.g. hydrotalcite, borosilicate glass, phosphosilicate glass),
Other inorganic powders may also be added in appropriate amounts as necessary.

[0025] A single-layer film, a two-layer film, a three-layer film, or other multilayer film may be formed by any method such as an inflation method, a T-die method, or a calendar method. In the case of a multilayer film, the thickness of the outermost layer containing the ethylene copolymer is not particularly limited, but it is preferably about 5 to 20 microns in consideration of film formability, thickness accuracy, and improvement effect.

[0026] The method of coating the thermoplastic resin film with the droplet agent may be any of various roll printing methods, dipping methods, spraying methods, and the like. Further, coating can be carried out by in-line coating performed subsequently after film formation, outline coating performed in the unwinding process after film formation and winding, or spray coating on the inner surface of the film after it is stretched.

[0027] Furthermore, as an auxiliary means for improving droplet persistence, the surface of the film before being coated with the droplet agent may be subjected to corona discharge treatment (treatment amount: 20 to 30 W·min/m2).

[0028]

[Function] In this invention, since the thermoplastic resin film that is the base film contains a specific ethylene copolymer in advance, the film is formed by chemical and electrostatic interactions due to the hindered amine in the copolymer. It is believed that the surface properties change significantly.

In other words, although the exact mechanism by which the inclusion of the ethylene copolymer improves the coating properties, droplet properties, etc. of the droplet is unknown, it imparts a certain kind of polarity to the film surface. This is thought to be due to significant changes in the chemical and electrostatic (charging characteristics) properties of the film surface.

[0030] Therefore, the wettability and adhesion of the surface coating type droplet agent to the thermoplastic resin film are improved, and therefore the uniformity of application of the droplet agent is also improved. That is, a small amount of droplet can be applied widely, evenly, and uniformly in a short time, and the cost is also low.

[0031] Furthermore, since the droplet is applied evenly, uniformly, and in a very strongly adhered state, the droplet effect is uniform, and the vinyl compound that is thought to contribute to the improvement of adhesion is ethylene. By being copolymerized with the thermoplastic resin film, the diffusion loss of the same compound from within the thermoplastic resin film is suppressed, and the droplet effect remains stable and unimpaired for several years.

[0032]

[Example] Films 1 to 13 of Examples with the formulations shown in Table 1
(single layer film) and films 14 to 18 (multilayer film) of Examples shown in Tables 2 and 3 were coated with the following droplet agent at various speeds using a brush roll coater with a roll width of 2000 mm. The coating properties and droplet properties were evaluated in the following manner. Droplet flow is achieved by setting up a small pipe house in the field.
A film was spread on this and evaluated. Note that the droplets were dried with hot air.

(1) The LDPE film (MFR 1.0, SG 0.920) of the example was added with ethylene copolymer pellets having a hindered amine in the side chain so that the proportion of vinyl compound units in the film was as shown in Table 1. The single layer film E1 shown in FIG. 1 is formulated as follows.
A film obtained by blending ethylene copolymer pellets having a hindered amine in the side chain and a hindered amine weathering stabilizer (Tinuvin 622 from Ciba Geigy) such that the proportion of vinyl compound units in the film is as shown in Table 2. 2
The two-layer film E2 shown in Fig. 2, ethylene copolymer pellets having hindered amine in the side chain, and silicon dioxide (
The three-layer film E3 shown in FIG. 3 is made by blending borosilicate glass powder containing SiO2 ) and boron oxide (B2 O3 ) as main components so that the proportion of vinyl compound units in the film is as shown in Table 3. , and were formed by a normal inflation method to obtain a film of an example and a film of a comparative example, respectively.

The thickness of the single layer film E1 is 100 μm and the width is 1800 mm. In addition, the two-layer film E2 is a laminated film of the a layer and the b layer as shown in FIG.
is a laminated film of c layer, d layer and e layer as shown in Figure 3,
The thickness of the c layer is 15μ, the thickness of the d layer is 70μ, and the thickness of the e layer is 15μ. The width of both laminated films E2 and E3 is 1800 mm.

In addition, in FIGS. 1 to 3, the a layer and c to e
The layers include an ethylene copolymer-containing layer, a layer b a layer not containing an ethylene copolymer, and D a droplet coating layer to be described later.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039] In Tables 1, 2, and 3, ethylene copolymers [A] and [B] have hindered amine in their side chains.
, [C] were produced by the following method.

Ethylene copolymer [A] 4-acryloyloxy-2,2,6, dissolved in ethylene and ethyl acetate using a stirring autoclave continuous reactor.
6-Tetramethylpiperidine and tert-butyl peroxypivalate dissolved in n-hexane as a catalyst were continuously fed, and the polymerization pressure was 2000 kg/c.
m2, and the copolymerization was carried out at a polymerization temperature of 200°C. The MFR of the obtained copolymer was 2.7 g/10 min, and the content of 4-acryloyloxy-2,2,6,6-tetramethylpiperidine units was 7.0% by weight.

Ethylene copolymer [B] Using the same equipment and method as for ethylene copolymer [A], a vinyl compound was
-Acryloyloxy-1,2,2,6,6-pentamethylpiperidine was substituted to produce an ethylene copolymer. The MFR of the obtained copolymer was 2.0 g/10 minutes,
The content of 4-acryloyloxy-1,2,2,6,6-pentamethylpiperidine units is 7.0% by weight.

Ethylene copolymer [C] Using the same equipment and method as ethylene copolymer [A], a vinyl compound was
-acryloyloxy-1-butyl-2,2,6,6-
An ethylene copolymer was produced by replacing tetramethylpiperidine. Note that the injection amount of the ethyl acetate solution of the vinyl compound was finely adjusted so that the vinyl compound content was 7.0% by weight. The MFR of the obtained copolymer was 2.5
g/10 min, 4-acryloyloxy-1-butyl-2
, the content of 2,6,6-tetramethylpiperidine units is 7
．． It is 0% by weight.

(2) Droplet agent A droplet 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 Co., Ltd.): 35 parts by weight (c) Polyoxyethylene lauryl ether (surfactant): 15 parts by weight ( d) Methanol: 450 parts by weight However, Polymer-A in the above active ingredients contains the following component (e
) to (h) were reacted at 60°C for 5 hours to form NH3
This is a compound neutralized with a 20% aqueous solution. (e) 2-hydroxyethyl acrylate: 99 parts by weight (f) Acrylic acid: 1 part by weight (g) Azobisisobutyronitrile (reaction catalyst): 0.
5 parts by weight (h) Methanol: 200 parts by weight (3) Evaluation of coating properties and droplet properties - The coating properties were comparatively evaluated by changing the coating speed. The evaluation method was to visually observe coating unevenness during coating. The results were summarized in the following three stages. ○: No uneven coating was observed during coating. △: Some coating unevenness is observed during coating. ×: Many uneven coatings were observed during coating.

(2) The droplet life of a film coated with a droplet agent at a coating speed of 8 m/min was comparatively evaluated. The evaluation method is as shown in Figure 4, with a height of 60 cm and a length of 1
．． The test film 2 was attached to a 5 m mini-house 1 and set in a field 3, and the water drop prevention property was evaluated.

The test was started on October 1, 1985, and changes over time in the state of water droplet adhesion were observed. The results of the water drop prevention evaluation were summarized in the following three stages. ○: No water droplets adhered to the inner surface of the film. (Flowing as a water film) △: Water droplets adhere to about 50% of the inner surface of the film. ×: Water droplets adhere to the entire inner surface of the film. In addition, ◯ to △ are intermediate between ◯ and △, and △ to × are between △ and ×.

(4) Evaluation Results The results of coating properties are shown in Table 4, and the results of droplet life are shown in Table 5.

[0047]

[Table 4]

[0048]

[Table 5]

As is clear from Tables 4 and 5, in terms of coatability, the films of Examples can be coated at a speed of 20 to 40 m/min, while the films of Comparative Examples can be coated at speeds of 10 to 15 m/min. Therefore, the film of Example is excellent. In addition, regarding the droplet life, the film of the example has a life of 2 to 4 years or more, whereas the film of the comparative example has a life of about 1 year, which shows that the film of the example is very superior. I understand.

Next, the following film was spread on a pipe house with a width of 5.4 m, a height of 2.8 m, and a length of 25 m, and the following droplet agent was sprayed onto the inner surface of the house using a power sprayer to coat the coated droplet agent. and evaluated droplet flow. (1) Film A film having a thickness of 100 μm and a width of 600 cm was formed by forming films 3, 4, 9, 15, and 18 of the above-mentioned Examples and films 1 and 2 of Comparative Examples by an inflation method.

(2) Droplet agent (a) Colloidal silica: 70% by weight (Catalyst Kasei Co., Ltd. Cataloid SI-350) (b) Silane derivative: 5% by weight (γ-ureidopropyltriethoxysilane) (c) Nonion Surfactant: 25% by weight (polyoxyethylene (7 mol) oleate ester) (a) to (
A droplet with an active ingredient concentration of 2% by weight obtained by adding water to the active ingredient of c) and stirring and mixing.

(3) Evaluation of coating properties and droplet properties (1) Coating properties were evaluated based on the time required for coating and the amount of droplet used, that is, the area coated with 1 liter of droplet. ■After application and drying (
The house side was left open for one day to thoroughly dry) and the house was sealed and evaluated by comparing and observing with the naked eye the condition of water droplets adhering to the house.

(4) Evaluation results Table 6 shows the evaluation results. From these results, the coating time for the film of the example can be reduced to about half compared to the film of the comparative example, and the coating area with 1 liter of droplet agent is also about 1.5 times larger. It can also be seen that the initial droplet flow properties are very good.

[0054]

[Table 6]

[0055]

[Effects of the Invention] As explained above, according to the present invention, since the above structure is adopted, the applicability of the droplet agent to the thermoplastic resin film and the droplet flow property after application of the droplet agent are improved. excellent,
Moreover, an inexpensive agricultural film and a method for producing the same can be obtained.

[Brief explanation of the drawing]

[Figure 1] Cross-sectional view of an agricultural film according to an example

[Figure 2] Cross-sectional view of the agricultural film according to the example

[Figure 3]
Cross-sectional view of an agricultural film according to an example

[Figure 4]
A perspective view showing the film of the example attached to a mini-house in a field.

[Explanation of symbols]

E1 Single layer film E2 Double layer film E3 Three-layer film

Claims (4)

[Claims] Claim 1: A thermoplastic resin film containing an ethylene copolymer having a hindered amine in its side chain is coated with a surface-applied droplet containing an inorganic hydrophilic colloid substance and a hydrophilic organic compound as main components. Agricultural film. [Claim 2] The thermoplastic resin is LDPE, EVA,
An ethylene copolymer which is a polyolefin such as LLDPE and which has a hindered amine in its side chain is formed by combining ethylene with the following general formula [Formula 1] (wherein, R1 and R2 are hydrogen atoms or methyl groups, and R3 is a hydrogen atom) or an alkyl group having 1 to 4 carbon atoms, respectively), wherein the proportion of the vinyl compound units in the thermoplastic resin film is 0.05 to 3.0% by weight. The agricultural film according to claim 1. 3. When coating a thermoplastic resin film with a surface-applied droplet containing an inorganic hydrophilic colloid substance and a hydrophilic organic compound as main components, the thermoplastic resin film has a hindered amine in its side chain in advance. A method for producing an agricultural film, which comprises containing an ethylene copolymer. [Claim 4] The thermoplastic resin is LDPE, EVA,
An ethylene copolymer that is a polyolefin such as LLDPE and has a hindered amine in its side chain is combined with ethylene by the following general formula: (each represents an alkyl group having 1 to 4 carbon atoms), and the proportion of the vinyl compound units in the thermoplastic resin film is 0.05 to 3.0% by weight. The method for producing an agricultural film according to claim 3.