JPH0770339A - Silver mulch film - Google Patents

Abstract

PURPOSE:To obtain a film improved in sunlight reflection and excellent in diminution of ground-temp. increase, vermin-repellent effect, etc. CONSTITUTION:The film is obtained by adding an aluminum metal powder and a crystallization inhibitor to an olefin resin and forming the mixture into a film. It may have a laminated thermoplastic resin layer on at least one side thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver mulch film comprising an olefin resin, a metal aluminum powder and a crystallization inhibitor, which is useful for suppressing a rise in soil temperature during crop cultivation and pest repellent.

[0002]

2. Description of the Related Art In recent years, while year-round cultivation of agricultural products is becoming popular, a so-called silver mulch film formed by adding metallic aluminum powder to a thermoplastic resin is used to suppress a rise in soil temperature and prevent pests from repelling insects. In order to have an effect, it is often used as a coating material for forcing cultivation of useful crops such as lettuce, radish, carrot, eggplant, etc., and recently, fruit trees such as apples, mandarins, peaches, carnations, coloring in flowers, improving sugar content Its use is expanding as a reflective film for

By the way, since the higher the reflectance of this silver mulch film is, the more effective it is in suppressing the rise in soil temperature and repelling harmful insects. Therefore, efforts to further increase the reflectance have been studied for a long time. A method in which a flaky metallic aluminum powder having a specific particle size is blended with a plastic resin and extrusion molding is performed (Japanese Patent Publication No. Sho 37-7142, Japanese Patent Laid-Open No. 54-145775), or a system comprising a thermoplastic resin and metallic aluminum powder. Further, a method of adding a pearl pigment or mica powder (JP-A-4-152833 and JP-A-4-190733) has been proposed.

However, in the former method of using metallic aluminum powder having a specific particle diameter among these, 7 μm
Although it is intended to obtain a film having high reflectance by using the metal aluminum powder having a relatively large particle size as described above, when a resin having a strong crystallinity such as an olefin resin is used as a base, a film forming process is performed. Since the transparency of the resin surrounding the metal aluminum powder is impaired by the crystallization at 1, the excellent reflection characteristics were not sufficiently exhibited even if the metal aluminum powder having a large particle size was used, which was not always satisfactory. . On the other hand, in the latter method of adding pearl pigment or mica powder, in addition to the problem of high cost, even in the case of a film of this type, the film strength of which is usually greatly reduced by the addition of aluminum metal powder,
Furthermore, the addition of such an inorganic substance promotes the deterioration of the physical properties of the film, which is not a preferable method.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to have an improved reflection characteristic for sunlight, an excellent suppression of a rise in soil temperature and an effect of repelling harmful insects. The point is to provide a silver mulch film.

[0006]

Means for Solving the Problems The inventors of the present invention have earnestly studied a method for improving the reflectance of a film made of an olefin resin and a metal aluminum powder, and as a result, have found that an olefin resin having originally poor transparency is selected. In the base silver film, from the viewpoint that it is the most rational and practical to show the excellent reflection characteristics of metallic aluminum powder as it is, the transparency of the olefin resin as the matrix The inventors have found that improving the properties is extremely effective in improving the reflectance, and have completed the present invention.

That is, the present invention is the first invention of the silver mulch film obtained by adding a metal aluminum powder and a crystallization inhibitor to an olefin resin to form a film, and the present invention is based on the olefin resin, the metal aluminum powder and the crystal. A second invention is a silver multi-film in which a thermoplastic resin is laminated on one side or both sides of a film formed by adding an anti-aging agent to form a film.

The olefinic resin used in the present invention is not particularly limited as long as it can be formed into a film. For example, low density polyethylene, high density polyethylene,
Linear low density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, ethylene-propylene copolymer and blends of two or more of these are included.
Of these, linear low-density polyethylene is particularly preferable from the viewpoints of economy and durability in consideration of use as an agricultural mulching material.

On the other hand, in the present invention, the aluminum metal powder added to impart the reflection characteristics to the above-mentioned olefin resin is a scaly, flaky or acicular powder having an average particle size of 1 to 30 μm, preferably 3 to 20 μm. These are used individually or in combination, of which scale-like metal aluminum powder is useful for giving high reflectivity to the film, and other shapes of metal aluminum powder are light-shielding properties of the film. Help improve.

The addition amount of the metallic aluminum powder is 2 to 30% by weight, preferably 3 to 20% by weight based on the olefin resin, and the addition amount of the metallic aluminum powder to the olefin resin is less than 2% by weight. In the case of, the reflectance is low, and therefore the effects of suppressing the rise in soil temperature and repelling pests are poor. Further, when the amount of the metallic aluminum powder added exceeds 30% by weight, not only the effect corresponding to it cannot be obtained, but also the drawdown property at the time of film formation is poor, the film formation stability is deteriorated, and the film strength becomes weak. The problem arises.

In the present invention, the crystallization inhibitor is basically compatible with the base olefin resin and suppresses crystallization during film formation of the olefin resin. Any film may be used as long as it can maintain the transparency of the film to a high degree, for example, a density of 0.91 g / cm ³ or less, preferably 0.905 g / cm ^3.
cm ³ or less ethylene and butene-1, hexene-1, 4,
-Copolymers with α-olefins such as methylpentene-1 and octene-1, ethylene-vinyl acetate copolymers having a vinyl acetate content of 10% by weight or more, ethylene-acrylic acid having an acrylic acid content of 10% by weight or more At least one of modified olefin resins such as copolymers, petroleum resins or terpene resins obtained by directly using petroleum unsaturated hydrocarbons, or hydrogenated products thereof can be used. Among these, ethylene-α-olefin copolymers having a density of 0.91 g / cm ³ or less are particularly preferable from the viewpoints of the effect of improving transparency, workability, and economical efficiency.

The amount of the crystallization inhibitor added varies depending on the type of the olefin resin, and therefore cannot be specified unconditionally, but it is usually 1 to 40% by weight based on the olefin resin, and the addition of the crystallization inhibitor causes the olefin resin to be added. It is preferable to determine the addition amount so that the haze of 1 is reduced by 1% or more.

In the present invention, the above-mentioned olefin resin, metallic aluminum powder, and crystallization inhibitor may be further added, if necessary, to a conventionally known antioxidant, antiblocking agent,
Various additives such as a lubricant, an antifogging agent, a coloring agent, a filler, and a metal oxide-based defoaming agent may be appropriately blended.

In the silver mulch film of the present invention, the composition comprising the above-mentioned olefin resin, aluminum metal powder and crystallization inhibitor is melt-kneaded by an extruder or the like, and then the inflation method, T-die method, calender method. It is obtained by forming a film in the form of a film, and the olefin resin used as the base at that time suppresses crystallization during film formation due to the action of the crystallization inhibitor, and as a result, metal aluminum powder added at the same time. The excellent reflection characteristics of (1) will be exhibited as it is, and a film with high reflectance will be obtained. Incidentally, the reflectance improving effect by the crystallization suppressing material of the present invention is remarkably exhibited particularly in the case of inflation molding among the above film forming methods,
The thickness of the film thus obtained is usually 10 to 200.
It is preferable that the thickness is in the range of 15 to 60 μm.

The silver mulch film of the present invention basically refers to a single-layer film obtained by adding metal aluminum powder, a crystallization inhibitor, etc. to an olefin resin as the film constitution. On one side or both sides of the above, a multilayer film in which a layer made of the same or different thermoplastic resin to which the above-mentioned crystallization inhibitor is added, if necessary, is laminated by a coextrusion method, an extrusion laminating method, a dry laminating method or the like is also included. It has an excellent advantage that film strength, weather resistance, pesticide resistance and the like, which are inevitably deteriorated by the addition of aluminum metal powder, are significantly improved.

As the thermoplastic resin laminated on one side or both sides of the silver film, it is preferable to use the same kind as the olefin resin constituting the silver film in terms of excellent interlayer adhesion. Other resins such as vinyl chloride resin, polyester resin and acrylic resin may be used. In addition, in the present invention, when the film structure is a multilayer structure of the above two layers or three layers,
The thickness of the reflective layer is preferably 10 to 70%, and more preferably 20 to 50% of the total film thickness in terms of film forming stability and reflectance.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

The methods for measuring and evaluating the physical properties used in the present invention are as follows. (1) Haze (unit:%) It was measured by a method according to JIS-K6714. (2) Reflectance (unit:%) Using a Hitachi spectrophotometer U-3500, the reflectance with respect to a light beam having a wavelength of 250 to 800 nm was measured, and the peak value between them was used as the reflectance.

Reference Example 1 Linear low-density polyethylene raw material (MI; 0.8 g / 10 min, density; 0.921 g / c
m ³ ) was inflation-molded with a 50φ inflation extruder under the conditions of an extrusion temperature of 190 ° C. and a blow-up ratio of 2.5 to produce a film having a thickness of 30 μm. The haze of this film was 5.0%.

Reference Example 2 MI 5.0 g / 10 minutes as a crystallization inhibitor was added to the above linear low-density polyethylene raw material,
A film having a thickness of 30 μm was prepared in the same manner as in Reference Example 1 except that 20% by weight of an ethylene-butene-1 copolymer (trade name: VL-400, manufactured by Sumitomo Chemical Co., Ltd.) having a density of 0.900 g / cm ³ was added. Was produced. The haze of this film was 3.0%.

Reference Example 3 MI was used as a crystallization inhibitor.
The same as in Reference Example 2 except that an ethylene-4-methylpentene-1 copolymer (trade name: Tuffmer A-4085, manufactured by Mitsui Petrochemical Co., Ltd.) having a density of 0.880 g / cm ³ (3.6 g / 10 min) was used. A film having a thickness of 30 μm was produced by the same method. The haze of this film was 3.3%.

Example 1 A low-density polyethylene-based masterbatch containing 40% by weight of metallic aluminum powder was added to the same linear low-density polyethylene raw material and crystallization inhibitor used in Reference Example 2 as described above. After blending so that the blending ratio of the above is 60:15:25 by weight,
Extrusion temperature 190 with 50φ inflation extruder
Inflation molding was carried out under conditions of a temperature of C and a blow-up ratio of 2.5 to produce a silver film having a thickness of 30 μm. The reflectance of this silver film is shown in Table 1.

Example 2 A silver film having a thickness of 30 μm was produced in the same manner as in Example 1 except that Tuffmer A-4085 used in Reference Example 3 was used as the crystallization inhibitor. The reflectance of this silver film is shown in Table 1.

[Comparative Example 1] The mixing ratio of the linear low-density polyethylene raw material and the metal aluminum powder-containing masterbatch was 75: 2 by weight without using the crystallization inhibitor.
A thickness of 3 is obtained by the same method as in Example 1 except that the thickness is 5
A 0 μm silver film was prepared. The reflectance of this silver film is shown in Table 1.

[0025]

[Table 1]

From the results shown in Table 1, the silver film of the present invention had a higher reflectance than the film containing no crystallization inhibitor (Comparative Example 1) and was excellent as a mulching material.

[0027]

As described above, according to the present invention, the action of the crystallization inhibitor suppresses the deterioration of the transparency due to the crystallization at the time of forming the olefin resin film, so that the excellent reflection characteristics of the aluminum metal powder can be obtained. Therefore, the silver film obtained is expected to have an excellent effect in suppressing an increase in soil temperature and repelling harmful insects when used as a mulching material during cultivation of agricultural products. Further, in the present invention, a multilayer film obtained by laminating a thermoplastic resin on one side or both sides of the silver film is not only a suppression of soil temperature rise and pest repellent, but also excellent in film strength, weather resistance, pesticide resistance, etc. And
It is even more suitable as a mulching material.

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Claims (3)

[Claims] 1. A silver multi-film obtained by adding aluminum metal powder and a crystallization inhibitor to an olefin resin to form a film. 2. A silver multi-film, wherein a thermoplastic resin is laminated on one or both sides of a film formed by adding a metal aluminum powder and a crystallization inhibitor to an olefin resin. 3. The crystallization suppressing material has a density of 0.91 g / cm 3.
The silver multi-film according to claim 1 or 2, which is an ethylene-α-olefin copolymer having ³ or less.