JPS5890960A - Agricultural laminated film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an agricultural laminated film. For more details,
The present invention relates to an agricultural laminated film that has good properties such as heat retention, transparency, weather resistance, antifogging properties, workability in spreading, greenhouse adhesion, dustproofness, and toughness.

Many plastic materials are used to secure facilities, and a large amount of plastic film is used in particular.

A typical example is polyvinyl chloride film (hereinafter referred to as
PvC film), polyethylene film (hereinafter referred to as PE film), -r-tyrene-vinyl acetate copolymer film (hereinafter referred to as EVA film), etc., which are used for greenhouse cultivation for the purpose of forced cultivation, It is widely used as a material for mulch cultivation and mulch cultivation (a cultivation method in which only the roots of plants are covered with a film, etc., in order to retain heat and prevent weeds from growing).

Among them, PVC film has excellent heat retention, transparency, and weather resistance.
It has excellent toughness, anti-fogging properties, house adhesion, and economy, and is the most commonly used. However, pvc
The film is somewhat inferior in workability and dust resistance, and has recently started to cause problems such as the generation of harmful gases when incinerating waste confectionery.

I'm hoping for a replacement.

On the other hand, PI! ! Film is superior to PVO film in terms of price, availability of raw materials, ease of spreading, dust resistance, and disposal.
Despite its advantages, its range of use is severely restricted due to poor heat retention, toughness, and house adhesion.

The KVA film has a performance that is approximately intermediate between that of the PVO film and the PZ film.

The above-mentioned film characteristics are as follows.

Heat retention: Maintains the temperature (air temperature and soil temperature) inside tunnels, greenhouses, etc. by absorbing and reflecting the radiation laid down at night from the ground, where the ground temperature has risen by absorbing solar heat during the day.

Stretching workability: The quality of workability (ease of handling) due to stickiness of the film.

House adhesion: When the film is spread over the frame of a house, tunnel, etc., there is a gap between the film and the frame.
Or whether the appearance of wrinkles is good or bad.

Dust resistance: The degree to which the transparency (sunlight transmittance) of a film decreases after a certain period of use.

Conventionally, various measures have been proposed to improve the drawbacks of each of the above-mentioned films. For PVO films, measures such as coating one side of the film with a methacrylic resin have been taken to improve the dust properties.

On the other hand, PK films have been improved by adding inorganic fillers, blending other polymers, plasticizers, and other organic substances to improve heat retention.

In addition, attempts have been made to improve the EVA film's stretching workability (stickiness) by roughening the film surface or blending other types of polymers.

However, when the above improvement measures are implemented, there are negative aspects such as a significant increase in cost and a decrease in original physical properties compared to before the improvement, and in both cases, it is still not possible to obtain a satisfactory agricultural film. The current situation is that this is not the case.

The inventor has developed heat retention, transparency, weather resistance, toughness, anti-fog properties,
After intensive study with the aim of providing an agricultural film that is not only excellent in various properties such as adhesion to greenhouses, ease of spreading, and dust resistance, but also economically advantageous, we have developed a three-layer polyolefin resin film. The present invention was based on the discovery that the object can be achieved by

That is, the gist of the present invention is a film formed by laminating polyolefin resin films into three layers such that adjacent layers are different from each other, the outer layer being a resin mainly composed of a linear low density polyethylene resin, and the middle layer being a resin film mainly composed of a linear low density polyethylene resin. is an ethylene-vinyl acetate copolymer, a haolefin-vinyl alcohol copolymer, or a mixture of the two, and the inner layer is a linear low-density polyethylene, an ethylene-vinyl acetate copolymer, or a mixture of the two. Exists.

The present invention will be explained in more detail below.

In the present invention, the polyolefin resin film is made of a resin whose main component is a linear low-density polyethylene resin which has flexibility and toughness. The resin constituting this layer is usually a linear low-density polyethylene resin itself or a mixture of a linear low-density polyethylene resin and an ethylene-vinyl acetate copolymer, the vinyl acetate content of which is 10% by weight. % is used.

The linear low-density polyethylene resin used in the present invention is a copolymer of ethylene and alpha-olefin, and is different from low-density polyethylene resins produced by conventional high-pressure methods.

Linear low density polyethylene resin is produced by low pressure method and α-
Examples of olefins include butene, hexene, octene, decene, and the like. The difference between the conventional high-pressure process low-density polyethylene resin and the low-pressure process low-density polyethylene resin used in the present invention is that the former has a multi-branched structure with many branches, while the latter has a linear structure. It has become. Additionally, when comparing the properties of the film, the latter has the advantage of being superior in tensile strength, impact strength, tear strength, and rigidity compared to the former, and can be made thinner to have the same strength. And potash, it will be cheap overall.

There are various manufacturing methods for linear low-density polyethylene resin, and they also differ in physical properties, but the linear low-density polyethylene resin used in the present invention is M process (melt index, 1710 m1).
n)=θ, /~10. Preferably 0. It is from evening to evening.

If M is smaller than 0.7, there is a drawback that during film forming, the load on the extruder is too high and productivity cannot be increased.

Furthermore, if M is larger than /θ, film forming itself is difficult, and the physical properties of the obtained film are impaired.

On the other hand, ρ(?/cc) of linear low density polyethylene resin
is θ, ri/+2 to θ, 93, preferably θ, ? /the law of nature~
θ, 93θ. If ρ is too small, the film will become stiff, and if it is too large, the film will wrinkle during molding.

In the middle layer, ethylene-vinyl acetate copolymer or olefin-vinyl alcohol copolymer is used alone or as a mixture of the two to improve heat retention, transparency, toughness, and house adhesion. . Ethylene-vinyl acetate copolymer is commonly used,
The vinyl acetate content concentration is about 2% by weight.

Olefin-vinyl alcohol copolymer refers to a saponified copolymer of olefin such as ethylene and vinyl acetate, and usually contains ethylene. ” Omob
q6, degree of saponification? θchi or more is used. Preferably, those having an ethylene content of 2J-cm1 or more and a saponification degree of 6-6 or more are used.

When using a mixture of ethylene-vinyl acetate copolymer and olefin-vinyl alcohol copolymer, the mixing ratio is IO weight of olefin-vinyl alcohol copolymer to ethylene-vinyl acetate copolymer. It is desirable to keep it within %. If it is more than 0% by weight, it is not practical because it is expensive and has little effect on improving heat retention.

As the inner layer, highly transparent linear low density polyethylene or ethylene-vinyl acetate copolymer is used alone or in combination with a mixture of the two.

The linear low density polyethylene and ethylene vinyl acetate copolymer used in the inner layer are the same as those used in the outer layer or middle layer described above.

As in the case of the linear low-density polyethylene resin, the polyolefin resin constituting the outer layer, the middle layer, and the inner layer has an M (tart index, 2//θ−)=0.0 from the viewpoint of film formability. 7~/θ, preferably 0. The one from dusk to evening is used.

Agricultural films such as those of the present invention are usually treated with an anti-fog formulation. The antifogging formulation is a so-called addition of an antifogging agent, and is carried out, for example, by adding it at the same time as the resin is melt-extruded using an extruder.

Alternatively, a resin grade for pickled vegetables containing an antifogging agent in advance may be used.

As the antifogging agent, for example, glycerol fatty acid ester, sorbitan fatty acid ester, polyethylene glycol fatty acid ester, triethanolamine fatty acid ester, modified products thereof, etc. are used.

The fatty acids constituting these esters are C72-C
Typical examples include lauric acid, valmitic acid, stearic acid, oleic acid, and linoleic acid.

The amount of the antifogging agent added is 7 to 6 parts by weight, preferably 7 to 5 parts by weight, based on 700 parts by weight of the three-layer sharp film resin.

In particular, when added only to the inner layer film, 0.7 to 70 parts by weight per 700 parts by weight of the inner layer film resin;
Preferably, θ is in the range of ta to ta parts by weight.

If anti-fog treatment is applied frequently, water droplets will adhere to the inside of the film applied to a house or tunnel, reflecting light from the outside. It easily flows down, does not reflect light from the outside, and allows the inside of a house or tunnel to be seen through. This is because even when measuring the temperature inside the greenhouse tunnel, there is a noticeable difference depending on the presence or absence of water droplets.The temperature on the right side is lower during the day, and the maximum temperature is also lower on a sunny day than when there are no water droplets. ing.

According to the findings of the present inventors, blooming of the antifogging agent occurs over time from the film obtained by mixing the above-mentioned antifogging agent into the resin, and the phenomenon of whitening of the film occurs. be.

This phenomenon occurs in the case of a three-layer film like the present invention.
It also occurs between layers, and unlike single-layer films, it is impossible to remove, and it significantly impairs the transparency of laminated films.

According to the findings of the present inventors, when the antifogging agent and a commonly used plasticizer are used together, the whitening phenomenon due to blooming is almost suppressed, and the transparency of the film is not impaired.

However, in the laminated film of the present invention, when a polyethylene resin such as linear low-density polyethylene is used alone as the inner layer, slight blooming of the plasticizer occurs even when an antifogging agent and a plasticizer are used together. This causes the film to become sticky, although this does not cause any practical problems.

Therefore, the inner layer in the laminated film of the present invention is mainly composed of linear low-density polyethylene, and an ethylene-vinyl acetate copolymer containing vinyl acetate, which is good at entrapping plasticizers, as described later. A mixture of is preferably used.

As the plasticizer, any commonly used plasticizer such as polyvinyl chloride can be used. For example, phthalate esters such as diptyl phthalate, hebutyl phthalate, di-2-ethylhexyl phthalate, hepthalic acid mixed group esters such as butyl benzyl phthalate, bunal lauryl phthalate, methyl oleyl phthalate, dioctyl adipate, adipine Aliphatic dibasic acid esters such as diisodecyl acid and dioctyl azelate-11, glycol esters such as diethylene glycol ester-1, fatty acid esters such as butyl oleate and methyl acetyl ricinoleate, triphosphate 1 Examples include phosphoric acid esters such as /zyl, trioctyl phosphate, and octyldiphenyl phosphate. Among them, phthalate esters and phosphate esters are preferably used.

According to the findings of the present inventors, the degree of inclusion of these plasticizers (the amount added that prevents the plasticizer from blooming over time on the surface of the molded film containing the plasticizer) (rJ, vinyl acetate content in polyolefin resin) Depends on quantity.

The amount of envelopment varies slightly depending on the type of plasticizer (difference in solubility parameter, molecular weight, etc.), but is roughly expressed by the following formula.

7 = /JX 10, / (where, The ratio of the antifogging agent to the plasticizer (a quantitative relationship that does not cause a whitening phenomenon) is such that the proportion of the plasticizer to 100 parts by weight of the antifogging agent is at least θ parts by weight, and preferably at least θ parts by weight. ” Second.

To laminate three layers of polyolefin resin film,
So-called co-extrusion laminate 4, in which each resin is fed into a single die from separate extruders using inflation molding or T-die molding, and is laminated and integrated inside the die and outside the die.
In the method, an adhesive (titanate, polyethyleneimine or isocyanate resin is usually used) is applied to a resin film, the solvent is evaporated through a drying oven, and the film to be laminated is layered on top of the dried state. A method of laminating by pressing under heat, extruding a polyolefin resin into a film by a T-die method, and, while the film is still in a molten state, allowing it to flow onto another resin film coated with an adhesive if necessary, Examples include a method of laminating by immediately passing between rolls.

Continuous coextrusion molding using the inflation method and the T-die method is generally used in consideration of productivity and the like.

The laminated agricultural film of the present invention is produced as described above, and the thickness ratio of each of the laminated films is
Mid-layer/inner layer ratio: Evening~3θchi/9θ~riθ%/Evening~3θ
ratio, preferably 70 to 2 ta / and O ~ ri θ も / / θ ~ u
t%. If the thickness of the middle layer is less than θ, the heat retention properties will not be good, and if the thickness of the middle layer exceeds θ, it will become difficult to control the thickness of the outer and inner layers, especially when forming three layers by continuous coextrusion molding. , impractical.

In addition, the thickness of the laminated film of the present invention is about riθ to 2θθμ, as is the case with commonly used agricultural films.

Furthermore, the agricultural laminated film of the present invention has the same formulation as commonly used/) agricultural films.

Specifically, 1. A weather-resistant formulation is applied to increase weather resistance. This formulation may be applied to all three layers of a three-layer film, but in actual use only the outer layer, which is attached to the outside, is sufficient.

The weathering formulation is the addition of so-called ultraviolet absorbers, light stabilizers, etc., and it is sufficient to add them at the same time when the resin is melt-extruded using an extruder.

Examples of ultraviolet absorbers include benzophenone, benzotriazole, salicylic acid derivatives, acrylonitrile derivatives, etc., and as light stabilizers, piperidine derivatives and the like are used.

The amount of these weather-resistant formulations to be added is θ/~3 weight ratio, preferably 05~. Double”
This is the range of ridges.

In particular, when it is added only to the outer layer film, the amount is 0.7 to 7% by weight, preferably 0.5 to 10% by weight, based on 700 parts by weight of the outer layer film resin.

In addition, commonly used additives such as lubricants, antioxidants, and heat stabilizers may be added as necessary when forming agricultural films.

As described in detail above, the agricultural film of the present invention has the advantages of each single film, and has the performance that could not be achieved with conventional single agricultural films (PVO film = 15-film, PE film, and VA film). By incorporating and laminating the film, it not only has a long lifespan without the problems of PVA film, but also has heat retention, transparency, weather resistance, anti-fog properties, ease of spreading (stickiness), house adhesion, dust resistance, It has excellent toughness and is extremely useful as a covering film for greenhouses, greenhouses, tunnels, etc.

Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the Examples.

Example / As a three-layer inflation molding device, a three-layer die with 73
A φ8F type extruder (manufactured by Tomy Kikai Kogyo ■) was used for the outer and middle layers, a 2-ta-2θ type extruder (manufactured by Kobe Steel, Ltd.) was used for the outer and middle layers, and a BCA extruder was used for the inner layer. -K
An O-type extruder (manufactured by Modern Machinery ■) was used, and a linear low-density polyethylene resin (M, ■ = 2.7
, ρ=θ, 9/≦, 16- Urtozetsuku0.2/NF (Trademark, Mitsui Petrochemical ■
)) and as an ultraviolet absorber, 2. ．． 2,6.6-titramethyl-coupiperidine penzoate 0 hawk weight factor and co-hydroxy-cou-octogycy penzophenone 0
．． A pellet obtained by kneading 3% by weight of ethylene-vinyl acetate copolymer [M, I =,
O1ρ=θ, 9j.

Vinyl acetate content - and weight %, KVAFIJX P Koza θ! (Trademark, manufactured by Mikata Polychemical ■)] was added to an extruder for the inner layer, and 100 parts by weight of linear low density polyethylene resin (same as the resin for the outer layer) was mixed with ethylene vinyl acetate copolymer (M, I = λ, evening, ρ=θ, 9, vinyl acetate content/de weight, KVAFLEX P/9θta (trademark, manufactured by Mikata Polychemical ■)] 701 weight mixed with Solgen as an antifogging agent! 7 parts by weight of θ (trademark, sorbitat monostearate, manufactured by Daiichi Kogyo Seiyaku ■) and dioctyl phthalate (Otona Kagaku ■!L!RI/
Knead the parts by weight, add a pellet, die humidity / 0C1 extrusion fg / 2. ! ky/hr.

Under the condition of blow ratio grouper, total N, iθθμ (outside IV!/
A three-layer laminate film having middle layer/inner layer, 2,5 μ/μ/μ/, and 2 μ) was obtained.

The following properties of the laminated film thus obtained were investigated.

Transparency (sunlight transmittance) and heat retention (air temperature, soil temperature)
: This f* layer film was spread in an airtight manner on an arch-shaped construction body to create a tunnel.

The arch-shaped construction body is made of foamed polyethylene sheet φ Sunhome, 231θ0#(
An iron box with a thickness of 8 t mm is filled with river sand, and the box is lined with a trademark made by Sanoro Kako ■. An arch made of round steel with a diameter of 6rTrm and having a length of θθ is constructed in the upper opening of the shaft.

The sunlight transmittance of the tunnel thus created was measured using a photocell type illuminance meter, Model 5PI-77 (manufactured by Tokyo Shibaura Electric ■).

Furthermore, the air temperature and soil temperature inside this tunnel were measured for one week (July 1981, located in Midori Ward, Yokohama City), and the daily high temperature, daily low temperature, and daily average temperature for the sunny Z days were measured. (average of values measured hourly 29 times over 7 days), daily maximum soil temperature, daily minimum soil temperature, and daily average soil temperature (average of values measured twice hourly over 7 days). The average results for 7 days are shown in Table-/.

Weather resistance: An accelerated test was performed using a Sunshine Weatherometer (manufactured by Suga Test Instruments), and the laminated film was stretched after the test until the residual rate decreased by θ compared to the initial elongation before the accelerated test. Judgment was made based on the irradiation time using a Weather-O-meter.

Anti-fogging properties: A laminated film was stretched for 9 months in a tunnel created to measure transparency and heat retention (from October 1930 to the end of 1930, Midori-ku, Yokohama City), and then The right portion of the subsequent film was visually observed. The antifogging property was judged based on the ratio of the right part to the whole.

A-2θ% or less, B-2θ to 2θ%, C-11 or higher Dustproof: A laminated film was stretched over the tunnel prepared for the measurement of transparency and heat retention, and after Z months. Judgment was made based on the rate of decrease in transparency (sunlight transmittance) relative to the transparency (sunlight transmittance) at the initial stage of expansion.

A-5 or less, B-10 to 10, and C-10 or higher.Extending workability: Judgment was made based on ease of handling when extending the laminated film to a tunnel straddle house.

A- Not sticky and easy to work with, B- Slightly sticky and has some difficulty in working, C- Extremely sticky.
Difficult to work with.

House adhesion: Judgment was made based on the degree of film tension when the laminated film was stretched on the frame of a house or tunnel.

A - There is no gap between the frame and the film, there is no walnut or wrinkles overall, B - There is a slight gap between the frame and the film, there are walnuts or wrinkles here and there, C - There is a gap between the frame and the film. Yes, the overall tension is poor, and there are many walnuts and wrinkles.

Strength at break: Tensile test (ASTM D, 5' and 2A
According to the law), the MD force direction and TD force direction of the laminated film
The strength at break in the force direction was measured.

Elongation at break: The elongation at break of the laminated film in the MD force direction and TD force direction was measured in the same manner as the method for measuring the strength at break.

Dirt drop impact: ASTMD/7θri A
Elmendorf tear strength: The MD force direction and TD force direction tear strength of the laminated film was measured in accordance with JI8 P#//6.

The respective results are shown in Table-/ and Table-1.

Example: As the resin for the middle layer, ethylene-vinyl acetate copolymer CM
, Aero, 0, ρ=O, cotton, vinyl acetate content 2% by weight, EvAFLmxP, 2z or (trademark, manufactured by Mitsui Polychemicals)] to] olefin-vinyl alcohol copolymer (ethylene-containing Weighing θmo1%,
M, ■-tsu,! , f) = /, , 2/j, GL-
E (Trademark/Nippon Gosei Kogyo Co., Ltd.)] 10 A laminated film was formed in the same manner as in Example, except that the pelletized material was added. I looked into it.

The results are shown in Table-/ and Table-co.

Comparative Example/, λ and 3 Agricultural PE of -1Oθμ when subjected to anti-scratch treatment in advance
Film, (manufactured by Mitsubishi Yuka), agricultural EVA film (
Genben 7JI] Kogyo (stock company) and agricultural PvC film (
(manufactured by Mitsubishi Monsanto ■) were investigated for various properties in exactly the same manner as in Example/, and each was designated as Comparative Example/, Comparative Example 2, and Comparative Example 3.

The results are shown in Table 7 and Table 1.

There is no difference in transparency (sunlight transmittance) compared to 23-24-KVA and P'VC films alone. However, in terms of air temperature and soil temperature, it is superior to conventional agricultural PM and EVA films, although the numerical differences are slight, and are on par with agricultural PVA films, which have been considered the best in the past. Therefore, slight differences in air temperature and soil temperature greatly affect the final yield and timing of agricultural crops, considering the cumulative temperature during the crop growing process.

Furthermore, the weather resistance and other properties are uniformly good, and the strength is especially excellent, so if the same strength is to be achieved, the thickness can be made thinner.

Thus, the laminated film of the present invention is suitable for agricultural use.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - Others/Names

Claims (1)

[Claims] (1) A film made of polyolefin resin films laminated into three layers so that adjacent layers are different from each other, the outer layer is a resin whose main component is linear low-density polyethylene resin, and the middle layer is ethylene-vinyl acetate. An agricultural laminated film comprising a copolymer, an olefin-vinyl alcohol copolymer, or a mixture of the two, and an inner layer comprising a linear low-density polyethylene, an ethylene-vinyl acetate copolymer, or a mixture of the two.