KR19990082936A - Coating fimls for agricultural use - Google Patents

Abstract

The present invention provides an agricultural coating film which is low in cost and difficult to block even when the films are in contact with each other, having anti-fog property, anti-fog property, and transparency, and heat retention.

The agricultural coating film of this invention consists of a thermoplastic resin resin containing the polyethylene oxide, the antifog, and the antifogant which have an average molecular weight of 10,000-1 million. Content of an antifogging agent is 1-3 weight part.

Description

Coating film for agricultural use {Coating fimls for agricultural use}

The present invention relates to an agricultural coating film used for vinyl house cultivation, tunnel cultivation and the like.

BACKGROUND OF THE INVENTION Although vinyl chloride is conventionally used as an agricultural film, vinyl chloride is expensive, difficult to process, and difficult to incinerate, which is an environmental problem. Therefore, recently, the film which uses polyolefin resin instead of vinyl chloride which has such a problem becomes the mainstream.

As an agricultural film, it is desirable to be excellent in transparency and heat insulation, and also excellent in anti-fog and fog prevention property. The anti-fog property is required to prevent dripping of water on the inside of the film covered with a plastic house and dripping onto flowers or leaves, etc. This is the performance required to prevent fog from being filled in the vinyl house and wetting the crops in the vinyl house or tunnel. This performance is required because of the lack of condensation, but when wetted by fog, it can cause damage to plants or pests.

Recently, in order to obtain a good antifogging property, the method of containing surfactant in a film is used. And in order to prevent generation | occurrence | production of a fog, the method of containing in a film the water repellent called a fog inhibitor is proposed (refer Japanese Unexamined-Japanese-Patent No. 59-35573 etc.).

In addition, in order to obtain excellent heat retention, it is effective to contain the water absorbent resin in the film. Therefore, the agricultural coating film (refer Japanese Unexamined-Japanese-Patent No. 4-61024) formed by adding superabsorbent resin as a water absorbent resin is proposed. A superabsorbent polymer is a generic term for a polymer having an absorbency of several tens to several thousand times its own weight by insolubilizing a water-soluble polymer such as a polymer electrolyte by graft polymerization or crosslinking polymerization, but such a superabsorbent polymer is insoluble. It is incompatible with the thermoplastic resin and needs to be dispersed as fine particles at the time of addition. Dispersion here requires a high level of skill and, if not properly dispersed, causes fish eye (small spherical lumps on the film) during film production. In recent years, with advances in dispersion technology, such a problem is alleviated. However, it is not preferable to use such a high molecular weight superabsorbent resin as the water absorbent resin in view of film transparency and price.

In view of such a point, an agricultural coating film using polyethylene oxide having a small average molecular weight as the water absorbent resin has been proposed (see Japanese Patent No. 2683923). According to this, the water absorbent resin can be finely dispersed and a film excellent in transparency and heat retention can be obtained.

As the film contains more water-absorbent resin, the amount of absorption increases, but the strength of the film decreases due to absorption. In order to obtain sufficient strength and absorbency at the same time, the thickness of the film must be thickened, so the transparency of the film is easily deteriorated and adversely affects the productivity of the crop. Therefore, it is preferable that the content of the water absorbent resin is smaller in terms of the strength of the film. In addition, since absorbent resin is expensive, it is preferable that the use amount of absorbent resin is small also in terms of cost. Therefore, it is desired to obtain sufficient absorbency while reducing the amount of absorbent resin.

Moreover, in these films, there exists a problem that antifog property falls with time after spreading, and the agricultural coating film which can maintain an antifog property for a long time is desired.

In addition, the film of the part corresponding to the wall surface of a vinyl house called a side is wound up in a summer house so that a heat may not be filled in a vinyl house, and it is fixed to a base stand etc. in the upper part. In autumn, the side wound up is unrolled and used as a wall of the vinyl house, but blocking becomes a problem at this time.

That is, since the films are in contact with each other in the wound state, if they are left in such a state under high temperature in summer, the parts in contact with each other are brought into close contact with each other. Therefore, there is a demand for an agricultural coating film that is hard to occur blocking and has good workability.

Accordingly, it is a problem to be solved by the present invention to provide an agricultural coating film having transparency, heat retention, anti-fog, anti-fog, low cost, and hardly blocking even when the films are in contact with each other.

Agricultural coating film of claim 1 of the claims of the present invention is characterized by consisting of a thermoplastic resin resin containing polyethylene oxide with an average molecular weight of 10,000 to 1 million, an antifog and an antifog.

The thermoplastic resin film containing the absorbent resin absorbs moisture to form a fine hydrous gel in the film, and the fine hydrogel diffuses light and absorbs infrared rays of a specific wavelength, thereby improving heat retention. In the present invention, since the superabsorbent resin is finely dispersed, not the superabsorbent polymer, the high molecular weight dispersion technique is not necessary, and the fish eye during film production due to improper dispersion is not generated.

Although the average molecular weight of polyethylene oxide is in the range of 10,000-5 million, it becomes difficult to disperse when an average molecular weight becomes large. Although it is possible to disperse even about 5 million with recent advances in the dispersion technique, in the present invention, it is preferable to use polyethylene oxide having an average molecular weight of 10,000 to 1 million.

The fine dispersion of the water-absorbent resin having a low molecular weight results in higher transparency of the film than the case where the super absorbent polymer is dispersed. In addition, the low molecular weight absorbent resin has a lower cost and lower manufacturing cost than the superabsorbent polymer. And since the anti-fog agent and the anti-fog agent are added, it is possible to prevent the dropping of condensation and the generation of the fog at the same time, and to prevent the damage or the disease of the cultivation caused by the wetness.

The agricultural coating film of claim 2, wherein the agricultural coating film of claim 1 is 3 to 15 parts by weight of polyethylene oxide having an average molecular weight of 10,000 to 1 million, and 1 to 5 parts by weight of an antifogging agent (preferably 1 to 3 parts by weight). And 0.1 to 3 parts by weight of a fog inhibitor.

According to this, 1 to 5 parts by weight (preferably 1 to 3 parts by weight) of an antifogging agent is added in an unexpectedly large amount. For several days after the film is made, bleeding causes the internal antifog to move to the film surface, leaving the film surface as if it has been sprayed with antifog powder. At this point of time, the transparency of the film is not good because of the antifogging agent located on the surface of the film. However, since the antifogging agent on the surface flows with rain water, dew, etc., the transparency is generally good within a few days after spreading in a vinyl house.

As described above, since the trace of the antifogging agent flows out after the antifogging agent flows on the film surface, the concave shape is formed. Therefore, even if the film is wound up, the substantial unevenness of the surface of the film causes the actual contact area of the film to be small (not in close contact with each other), making it difficult to block.

In addition, a fine anti-fog on the surface flows out from the surface of the film to form a fine passage through which water penetrates. Thereby, since the water absorbing resin which contacts water becomes large, sufficient water absorption can be obtained even if the content of the water absorbing resin in a film is reduced. Therefore, the decrease in strength due to the water absorbent resin can also be reduced, and since the amount of the expensive water absorbent resin is reduced, a low cost film can be produced. For example, conventionally, about 5 parts by weight of an absorbent resin added by about 8 parts by weight can be added, and the manufacturing cost can be greatly reduced.

Moreover, although the agricultural coating film containing surfactant as an antifog agent is already known, the addition amount of an antifog agent in these films is about 0.2 weight part. Therefore, minute unevenness | corrugation of a film surface hardly arises, and an effect cannot be expected from a blocking prevention viewpoint. Similarly, there is almost no passage of fine water from the surface of the film to the inside, and thus a sufficient water absorption cannot be obtained with a small amount of water absorbent resin as in the present invention.

In other words, the effect of preventing blocking and securing a sufficient absorption rate with a small amount of the water absorbent resin can be achieved only by containing an amount of antifog agent (1 to 3 parts by weight) which is unprecedented in the prior art.

The agricultural coating film of claim 3 is laminated in two or three layers, at least one of which is a thermoplastic resin resin containing polyethylene oxide having an average molecular weight of 10,000 to 1 million, an antifog and an antifog. Characterized in that made.

This is a film in which the film of the composition different from the film of Claim 1, 2 is laminated | stacked in two layers or three layers, and film strength and heat insulation can be improved by combination. For example, it is composed of three layers of an intermediate layer containing no absorbent resin and a surface layer located on both sides of the intermediate layer, and the surface layer is a thermoplastic water containing polyethylene oxide having an average molecular weight of 10,000 to 1 million, an antifog and an antifog. The film etc. which consist of oil-based resin are considered.

The agricultural coating film according to claim 4 is characterized in that the polyethylene oxide having an average molecular weight of 20,000 to 500,000 according to claim 1, 2 or 3.

According to this, in the film of each claim mentioned above, since microdispersion of the polyethylene oxide which is an absorbent resin becomes easier, and film manufacture becomes easier, it is more preferable.

The present invention is explained below using suitable examples.

In the present invention, it is preferable to contain 1 to 20 parts by weight of polyethylene oxide having an average molecular weight of 10,000 to 1 million, 0.01 to 5 parts by weight of an antifog, and 0.1 to 0.5 parts by weight of an antifog, but an average molecular weight of 10,000 The range of 3-5 weight part of polyethylene oxides, 1-3 weight part of antifog agents, and 0.1-0.5 weight part of antifog agents is more preferable. More preferably, it is preferable to use polyethylene oxide having an average molecular weight of 20,000 to 500,000.

Example 1

Ethylene vinyl acetate copolymer [Evatate (trademark) H2020 made by Sumitomo Chemical Co., Ltd. H2020, melt index MI ≒ 1.5g / 10min, vinyl acetate content 15weight%, the same as the following Example as a thermoplastic resin as a base thermoplastic resin Do. Simply referred to below as "EVA"] 5 parts by weight of polyethylene oxide [Alcox (registered trademark) E-30, manufactured by Meisei Chemical Co., Ltd.], 100 parts by weight and an absorbent resin having an average molecular weight of 300,000 to 500,000; It contains 2 parts by weight of a glycerin fatty acid ester ("Likenmal" AF82 manufactured by Rikenvitamin Co., Ltd.) as an antifogging agent and 0.5 parts by weight of a silicone surfactant (SH200 oil manufactured by Toray Dou Corning Silicone Co., Ltd.) as an antifog.

In the present invention, a super absorbent polymer is not used, and polyethylene oxide having an average molecular weight of 10,000 to 1 million is used as the absorbent resin. Polyethylene oxide with an average molecular weight of 10,000 to 1 million has a large difference in absorption compared to super absorbent polymers, and does not insolubilize due to chemical and physical crosslinking and is finely dispersed in a thermoplastic resin. The same problem does not occur. In particular, in the case of using polyethylene oxide having an average molecular weight of 20,000 to 500,000, as in this embodiment, fine dispersion becomes easier. The film is made to be 0.075 mm thick by inflation molding. The thickness of the film varies depending on the application, but is usually about 0.02 to 0.15 mm.

In addition, although a silicone type surfactant is used as a fog inhibitor in this Example, a well-known fog agent can be used as a fog agent, The thing which mixed fluorine type surfactant, a fluorine type surfactant, and silicone type surfactant can be used. In addition, as the antifogging agent, known surfactants such as sorbitan fatty acid esters, glycerin fatty acid esters, triethanol fatty acid esters, polyethylene glycol fatty acid esters and the like can be used.

Example 2

In Example 1, a single layer film is produced, but in this example, a three-layer structure is produced. The intermediate layer located in the middle of the three layers does not contain the absorbent resin, but the surface layer located on both sides of the intermediate layer contains the absorbent resin.

Specifically, the intermediate layer contains 100 parts by weight of EVA and 20 parts by weight of SiO ₂ additive. The addition of the SiO ₂ -based additive here is because far infrared rays are absorbed by the SiO ₂ -based additive and thus are not taken out of the vinyl house.

The surface layer may be made of the same material on both sides, but in this embodiment, one surface layer (outer layer) is 100 parts by weight of EVA, 5 parts by weight of polyethylene oxide, and a glycerin fatty acid ester [Likenmal (manufactured by Rikenvitamin Co., Ltd.) as an antifogging agent. AF-82], and the other surface layer (inner layer) is 100 parts by weight of EVA, 3 parts by weight of polyethylene oxide, and a glycerin fatty acid ester [Likenmal (registered trademark, manufactured by Riken Vitamin Co., Ltd.) as an antifogging agent. ) ”AF-82] 1 part by weight and 1 part by weight of a silicone surfactant (SH200 oil manufactured by Toray Dow Corning Silicone Co., Ltd.) as an antifog agent.

Each layer is 0.025 mm thick, and the thickness of the whole film formed by laminating three layers is 0.075 mm. When used, the surface layer (inner layer) containing the antifog agent should be inside the vinyl house to prevent the generation of fog in the vinyl house. The reason for not adding a fog inhibitor to the surface layer (outer layer) is that it is not a problem to generate fog outside the plastic house.

In accordance with the addition of SiO ₂ because it is in a configuration laminated between the strength of the intermediate layer, but lower (it is about) the solid surface layer on both sides as the entire film can be obtained a sufficient strength. In addition, although the example which is three layers was described in this Example, it can manufacture with two layers of films similarly.

Example 3

This example is a film having the same structure as in Example 1 except that the content of the antifogging agent is small. That is, 5 parts by weight of polyethylene oxide ("Alcox (registered trademark) E-30" manufactured by Meisei Chemical Co., Ltd.) having an average molecular weight of 300,000 to 500,000 as EVA as a basic thermoplastic resin and an absorbent resin. It contains 0.2 weight part of glycerin fatty acid esters ("Likenmal" AF-82 by Rikenvitamin Co., Ltd.) AF-82 as an inhibitor, and 0.5 weight part of silicone type surfactant [SH200 oil by Toray Dow Corning Silicone Co., Ltd.] as an antifog agent.

Comparative Example

For comparison, a film containing no antifog is prepared. That is, 100 parts by weight of EVA as a base thermoplastic resin and 5 parts by weight of polyethylene oxide [Alcox (E-30) manufactured by Meisei Chemical Co., Ltd.] As an inhibitor, 0.5 weight part of silicone type surfactant (SH200 oil by Toray Dow Corning Silicone Co., Ltd.) is contained. No antifog is added.

[Comparison Test]

Comparative tests are carried out using the above Examples and Comparative Examples. First, when each film was immersed in water and the water absorption was examined, it is as follows.

Example 1: 7.2 (% by weight)

Example 2: 4.3 (% by weight)

Example 3: 5.0 (% by weight)

Comparative Example: 3.2 (wt%)

Accordingly, in the present invention containing an antifog, the absorption rate is greater than that of the comparative example containing no antifog, and the case of Example 1, which has a high content of the antifog, is less than that of Example 3, which contains less antifog. It can be seen that the water absorption is large.

Next, one week after film production, the film of each example and each comparative example was unfolded to make a vinyl house. After the unfolding, and after 30 days and 90 days, the fog generation state and the water droplet adhesion state in the plastic house are examined. For the fog, no fog is generated even when using any film (including a comparative example).

In Example 1 and Example 2, water droplets are hardly adhered in the vinyl house at any point in time, but in Example 3, water droplets are not immediately observed after being unfolded, but after 30 days, water droplets are adhered to the inner surface of the film. After 90 days have elapsed, the amount of water droplets is increased, and in the comparative example, it is anti-fogging immediately after unfolding and there is no adhesion of water droplets, but after 30 days (after 90 days of course), Attachment is confirmed.

In addition, each film that is being used as a side in the actual work place is wound in a spiral, left for one summer, and then released to compare the blocking state. In Examples 1 and 2, blocking does not occur, and can be easily solved, so that workability is good. In Example 3, blocking occurs and it is difficult to solve, resulting in deterioration of workability. In addition, in the comparative example, due to strong blocking, it cannot be solved and cannot be reused.

Moreover, as a result of investigating the heat retention in a vinyl house, Example 1 and Example 2 have good heat retention in a vinyl house compared with Example 3 and a comparative example. This is because, due to the fine irregularities on the surface of the film, even if the amount of the water absorbent resin in the film is a small amount, contact between the water and the water absorbent resin is ensured and sufficient heat retention is exhibited.

Therefore, by adding an antifog agent and an antifog agent, it is possible to provide an agricultural coating film having antifog and antifog property along with transparency and heat retention. However, by adding 1 part by weight or more of an antifog agent, the following excellent effects can be obtained. Can be.

(1) The synergistic effect between polyethylene oxide and the antifogging property can maintain the antifogging property over a long period of time.

(2) When rolling up (in actual use), there is little blocking occurrence and workability is good.

(3) The addition amount of the water absorbent resin (polyethylene oxide) is reduced so that a cheap and safe film can be produced.

In addition, in the present invention, polyethylene oxide having an average molecular weight of 10,000 to 1 million is used as the water absorbent resin. As the average molecular weight is increased as described above, high technology is required for dispersion, and if the dispersion is not properly performed, the occurrence of fish eye, etc. This is because of the problem. In recent years, however, with the advance of dispersion technology, even if the average molecular weight is about 5 million, it is possible to disperse well. In such a case, adding an antifog agent and an antifog agent as in the present invention has the same effect as the present invention. The film which has can be manufactured.

As described above, according to the present invention, it is possible to provide an agricultural coating film having transparency, heat retention, and fog prevention and anti-fogging properties, and especially when the amount of the anti-fogging agent is added, blocking occurs even when the films are in contact with each other. It is difficult to provide an agricultural coating film which is inexpensive and low in strength.

Claims (4)

An agricultural coating film comprising a thermoplastic resin containing an average molecular weight of 10,000 to 1 million polyethylene oxide, an antifog and an antifog. The agricultural coating film according to claim 1, which contains 3 to 15 parts by weight of polyethylene oxide having an average molecular weight of 10,000 to 1 million, 1 to 5 parts by weight of an antifog and 0.1 to 3 parts by weight of an antifog. An agricultural coating film comprising two or three layers, wherein at least one layer is made of a thermoplastic resin resin containing polyethylene oxide having an average molecular weight of 10,000 to 1 million, an antifog and an antifog. The agricultural coating film according to any one of claims 1 to 3, wherein polyethylene oxide having an average molecular weight of 20,000 to 500,000 is used.