JPH03255140A - Polyethylene terephthalate film for agricultural use - Google Patents

Abstract

PURPOSE:To prevent the degradation of the transparency of a polyethylene terephthalate film by algae appearing when spread and used outdoors by coating one side of the film with a specific acrylic resin and the other side with a specific comspn. CONSTITUTION:The title film is prepd. by coating one side of a polyethylene terephthalate film with an acrylic resin contg. an ultraviolet absorber and an org. nitrogen algaecide and the other side with a compsn. mainly comprising a colloidal silica and/or an alumina sol and a binder. A nonoriented or biaxially oriented polyethylene terephthalate film may be used, the biaxially oriented being pref. because of the strengths, and a pref. film thickness is 0.01-0.3mm. The use of a benzophenone or benzotriazole ultraviolet absorber is pref.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to polyethylene terephthalate films for agricultural use. More specifically, the present invention relates to an agricultural polyethylene terephthalate film that prevents a decrease in transparency caused by the growth of algae when stretched outdoors.

rPrior Art In recent years, with the expansion of greenhouse horticulture, the area of facilities has increased, and agricultural polyethylene terephthalate films have come to be used in many different regions. At the same time, as the environments in which they are used have become more diverse, the environmental conditions inside and outside of greenhouses have become relatively hot and humid, resulting in algae growing on the outside or inside of greenhouses made of polyethylene terephthalate film and allowing sunlight to pass through. In addition to inhibiting the mechanical strength of the film, there are also many cases where it reduces the mechanical strength of the film.

In general, algae are microorganisms that exist in surface water, and because they contain chlorophyll, they have the ability to photosynthesize, and their surfaces are often covered with a sticky substance, so the growth of algae on the film can be physically controlled. It is difficult to prevent it mechanically or remove it once it occurs.

To remove algae from conventional algae-infested films,
The only options are to physically scrape it off or let it dry and wait for it to fall off naturally, but either method is difficult to work with in large facility greenhouses, and when trying to kill algae with chemicals, for example. Although it is possible to kill algae by using a sodium hypochlorite aqueous solution, it is necessary to remove the dead algae from the film, and the algaecide effect cannot be expected to last for a long time.

"Problems to be Solved by the Invention" Under such circumstances, the present inventors have developed a method that prevents the decrease in transparency caused by the growth of algae caused by spreading outdoors, and also has an excellent long-lasting effect. As a result of intensive studies aimed at providing a polyethylene terephthalate film for agricultural use, the present invention was developed.

"Means for Solving the Problems" The gist of the present invention is that an acrylic resin coating containing an ultraviolet absorber and an organic nitrogen algaecide is formed on one side of a polyethylene terephthalate film. The present invention relates to an agricultural polyethylene terephthalate film on which a coating of a composition containing colloidal silica and/or alumina sol and a binder as main components is formed on the other side of the film.

The present invention will be explained in detail below.

The polyethylene terephthalate referred to in the present invention is not only a non-copolymerized polyethylene terephthalate homopolymer, but also a copolymerized polyethylene terephthalate in which the repeating unit of ethylene terephthalate is 85% or more and the remainder is other components, It includes a polymer blend in which polyethylene terephthalate accounts for 85% by weight or more, and the remaining 15% by weight or less consists of other polymers. Other polymers that can be blended include polyamides, polyolefins, and other types of polyesters. Additives such as lubricants, colorants, stabilizers, and antioxidants, which are usually added to polyethylene terephthalate, can be added to this polyethylene terephthalate, if necessary.

The agricultural polyethylene terephthalate film according to the present invention may be unstretched or biaxially stretched, but from the viewpoint of film strength, biaxially stretched is preferred.

When stretching into two wheels, it is preferable to stretch 2.0 to 5.0 times in length and width. If the stretching ratio is less than 2.0 times, the strength of the product will not be sufficient, which is undesirable. If the stretching ratio exceeds 5.0 times, the strength of the product will be sufficient, but the manufacturing work will be difficult. This is not desirable. The stretching ratio is particularly preferably in the range of 2.5 to 4.0 times in both biaxial directions. The method for producing a biaxially stretched film is not particularly limited, and any conventionally known method may be used, such as sequentially or simultaneously stretching the film in two directions.

The agricultural polyethylene terephthalate film according to the present invention preferably has a thickness of 0.01 to 0.311 Iol. If the thickness is less than 0.01 mm, the strength of the product will not be sufficient, so it is not preferable. , 3+
Exceeding ++w is not preferable because the film becomes hard and difficult to handle.

The agricultural polyethylene terephthalate film according to the present invention has an acrylic resin coating containing an ultraviolet absorber and an organic nitrogen algaecide formed on one side thereof. Examples of the ultraviolet absorbent used here include the following.

2-ethylhexyl-2-cyano-3,3'-diphenylacrylate and ethyl-2-cyano-3,3'-diphenylacrylate, which are cyanoacrylate ultraviolet absorbers.

2-Hydroxy-, a hensifenone UV absorber
4-Methoxyhensiphenone, 2,4-dihydroxyhensiphenone, 2-human"roxy4n-octoxyhenduphenone, 2-hydroxy-4-methoxy-2'-
Carboxyhensophenone, 2,2゛-dihydroquine-4,4゛-dimethoxyhendophenone, 2-hydroxy-4-benzoyloxyhendophenone, 2,2゛-dihydroquine-4methoxybenduphenone, 2-hydroxy -4methoxy-5-sulfonehensiphenone, 2.2
', 4゜4゛-tetrahydroxyhensiphenone, 2,
2'dihydroxy-4,4'-dimethoxyhensophenone, 2-hydroxy-5-chlorohensiphenone, bis-(2-methoxy-4-hydroxy-5-hensoylphenyl)methane.

2-(2゛-
Hydroxyphenyl)benzotriazole, 2-(2“
-Hydroxy-5°-methylphenyl)benzotriazole, 2-(2'-hydroxy-5-methylphenyl)-5-carboxylic acid butyl ester benzotriazole, 2-(2'-hydroxy-5'-methylphenyl) -5,6-cyclobensotriazole, 2-(2
"-Hydroxy-5'-methylphenyl)-5-ethylsulfonebenzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy- 5°−1
-butylphenyl)benzotriazole, 2-(2'-
Hydroxy-5′-aminophenyl)benzotriazole, 2(2′-hydroxy-3”,5”-dimethylphenyl)benzotriazole, 2-(2′-hydroxy3′,5′-dimethylphenyl)-5-methoxy Benzotriazole, 2-(2″-methyl-4′-hydroxyphenyl)benzotriazole, 2-(2-stearyloxy-3′,5′-dimethylphenyl)-5-methylbenzotriazole, 2-(2hydroxy- 5-carboxylic acid phenyl)benzotriazole ethyl ester, 2-(2'-hydroxy-3'-methyl-5°-t-
butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5
-chlorobenzotriazole, 2-(2'-hydroxy-3'-t-phthyl-5'-methylphenyl)-5-1
0 lobenzotriazole, 2-(2“-hydroxy-5
゛-methoxyphenyl)hencytriazole, 2(2゛-hydroxy-3゛,5°-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2''-hydroxy-5''-cyclohexylphenyl)hencytriazole Triazole, 2-(2'-hydroxy 4°, 5'-dimethylphenyl)-5-carboxylic acid henctriazole butyl ester, 2-(2'-hydroxy-3', 5'-dichlorophenyl]benzotriazole, 2- (2″-hydroxy-4°,5″dichlorophenyl)benzotriazole, 2(2′-hydroxy-3′,5′-dimethylphenyl)5-ethylsulfonebenzotriazole, 2-
(2″-hydroxy-4′-octoxyphenyl)benzotriazole, 2-(2′-hydroxy-5°methoxyphenyl)-5-methylbenzotriazole, 2-(
2°-Hydroxy-5′-methylphenyl)-5-carboxylic acid ester benzotriazole, 2-(2′-acetoxy-5′-methylphenyl)benzotriazole.

Although the above-mentioned ultraviolet absorbers can be mentioned, it is particularly desirable to use benzophenone-based ultraviolet absorbers or benzotriazole-based ultraviolet absorbers.

Examples of organic nitrogen algaecides include imidazole derivatives such as 2-(4-thiazolyl)-benzimidazole and 2-methoxycarbonylamino-benzimidazole.
Derivatives such as 3,4.5-tribromusalicylanilide; 3-trifluoromethyl-4,4'-dichloro-N
Urea derivatives such as N'-dichloro-N,N'-biphenylurea; Ammonium derivatives such as ammonium N-methyldithiocarbamate and tetradecyldimethylbenzylammonium chloride; 2,3,5.6-titrachloro-4(methylsulfonyl)pyridine Pyridine derivatives such as 2-methylthio-4-t-butylamino-6-cyclopropyl-amino-S-triazine, N,N-dimethyl to N'-(fluorodichloromethylthio)-N'-phenyl N-haloalkylthio derivatives such as sulfamide; phthalimide derivatives such as N-(fluorodichloromethylthio)-phthaligod, N1.1,2.2-tetrachloroethylthiotetrahydrophthalimide, 2,4,5.6 - Nitrile derivatives such as titrachloroisoaphthalonitrile; benzothiazole derivatives such as 2-(4-thiocyanomethylthio)benzothiazole;
Substituted pendylamine derivatives; dithiocarbamate derivatives such as tetramethylthiuram disulfide can be mentioned. These organic nitrogen-based algaecides can be used alone or in combination of two or more, and if necessary, algaecides other than organic nitrogen-based algaecides, such as parachloromethaxylenol, may be used at the same time. You may use it.

The total amount of ultraviolet absorber and organic nitrogen algaecide is:
It is selected within the range of 1 to 50 parts by weight, preferably within the range of 2 to 30 parts by weight, based on 100 parts by weight of the acrylic resin. If the amount is less than 1 part by weight, the algae-proofing properties of the polyester film will not be improved, and if the amount is more than 50 parts by weight, the transparency of the film formed on the film will decrease, causing problems.

The mixing ratio of the ultraviolet absorber and the organic nitrogen-based algaecide is preferably 20:1 to 1:15 by weight. If the proportion of the ultraviolet absorber is higher than the above range, it will be difficult to achieve an anti-algae effect, and if it is lower than the above range,
The problem is that the anti-algae effect does not last long enough.

In the present invention, acrylic resins include homopolymers made of monomers of acrylic acid, acrylic esters, methacrylic acid, and methacrylic esters, copolymers made of two or more of these monomers, and one or more of these monomers. It refers to a copolymer containing vinyl monomers as the main component and other vinyl monomers that can be copolymerized with these. Other vinyl monomers include crotonic acid, itaconic acid, acrylonitrile,
Examples include styrene, vinyl chloride, hydroxyalkyl (meth)acrylate, and the like.

Examples of the polymerization initiator used in producing the acrylic resin of the present invention include persulfates such as ammonium persulfate and potassium persulfate; organic peroxides such as acetyl peroxide and benzoyl peroxide. These are used in an amount of 0.1 to 10% by weight based on the total amount of monomers charged.

Acrylic resins can be produced by any polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. The obtained acrylic resin can be further added with a compound such as vinyl chloride/vinyl acetate resin, vinyl chloride resin, cellulose ether, etc.

The above composition may further contain a liquid dispersion medium, if necessary. Such liquid dispersion media include monohydric alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin; cyclic alcohols such as dibenzyl alcohol; cellosolve acetates; acetic acid. Examples include esters; aliphatic hydrocarbons; aromatic hydrocarbons; alicyclic hydrocarbons; ketones.

These liquid dispersion media may be used alone or in combination, but
It is preferable to decide by taking into consideration the dispersion stability of the coated Mi base material, the wettability after coating on the film surface, the difficulty of removing the liquid dispersion medium, and economic efficiency.

The above composition may further contain an antifoaming agent, a surfactant, a lubricant, an antistatic agent, a plasticizer, an antioxidant, a crosslinking agent, a light stabilizer, a film-forming aid, a thickener, and a pigment. , pigment dispersants, inorganic fillers, and other conventional additives can be mixed.

In addition, the coating film of this composition formed on the surface of the base film has a solid content of 0.1 to 10 g/m.
In particular, it is preferably in the range of 0.5 to 5 g/bo.

A film of a composition containing colloidal silica and/or alumina sol and a binder as main components is formed on one side of the agricultural polyethylene terephthalate film according to the present invention. The film derived from this film has moisture absorption and water absorption properties, so it has the effect of removing water that causes algae growth inside and outside the greenhouse, and therefore improves the algae-proofing properties of the hydrophobic polyethylene terephthalate film.

The colloidal silica and/or alumina sol preferably has an average particle diameter of 5 to 100 mμ. If the average particle diameter exceeds 100 mμ, the coating film becomes white and tends to devitrify.
When it is less than mμ, the composition lacks stability, which is not preferable. These may be used alone or in combination. In addition, when used alone or in combination, two types of plates with different average particle diameters-E
You may use a combination of these. When combining both, the weight ratio of colloidal silica/alumina silica is 95 to 5.
A ratio of 15 to 95 (total 100) is preferable.

The alumina sol may be a commercially available product itself, or an aqueous sol obtained by dispersing commonly available alumina powder in water. When alumina sol is dispersed in water at a high concentration, it exhibits so-called thixotropy, meaning that the viscosity of the dispersion increases rapidly, making it difficult to obtain a homogeneous dispersion. However, when using a medium shear internal stirrer such as a colloid mill, , a homogeneous dispersion can be obtained. Furthermore, when colloidal silica is mixed into this dispersion, the viscosity of the dispersion can be lowered.

On the other hand, colloidal silica has particle surfaces that are negatively charged in most cases, but when used in combination with alumina sol, it is not preferable to use negatively charged colloidal silica. This is because when colloidal silica and alumina sol are mixed, the mixed dispersion rapidly aggregates and gels, resulting in poor dispersion.

Therefore, the colloidal silica preferably has a positively charged particle surface.

As the binder component, it is necessary to select one that has good affinity with a hydrophilic medium such as water or alcohol, which is a dispersion medium for alumina sol or silica sol. Specifically, surfactants or thermoplastic resins having such affinity are used.

The type of surfactant used as a binder component must be changed depending on colloidal silica or alumina sol. For example, in general, combinations of negatively charged silica sol and cationic surfactant, and positively charged alumina sol and anionic surfactant should be avoided. These combinations tend to cause gelation of the sol and aggregation/separation of the composition, making application difficult.

Thermoplastic resins used as binder components include:
As mentioned above, acrylic resins, vinyl chloride-vinyl acetate resins, polyethylene resins, vinyl chloride resins, vinylidene chloride resins, which have good affinity with the medium (usually water),
Examples include polyurethane resins, polycarbonate resins, styrene resins, vinyl acetate resins, unsaturated polyester resins, and acrylic resins are particularly preferred.

The main components, colloidal silica and/or alumina sol, are blended in an amount of 0.00% of the binder component in terms of solid content weight ratio.
It is preferably in the range of 5 to 40 times. If it exceeds 40 times, not only will the moisture absorption and water absorption effect not improve in proportion to the amount blended, but also the coating film formed after application will become cloudy and the light transmittance will decrease. Furthermore, the coating film tends to become rough and brittle. On the other hand, when it is less than 0.5 times, it becomes difficult to exhibit sufficient moisture absorption and water absorption effects.

Furthermore, this composition may also contain a crosslinking compound that crosslinks the binder components. By doing so, the water resistance of the coating can be improved. The amount of the crosslinking compound used is 0.1 to 3 based on the solid content of the binder component.
A range of 0% by weight, especially a range of 0.5 to 10% by weight is preferred.

In addition, a composition containing colloidal silica and/or albinazol and a binder as main components may contain an antifoaming agent, if necessary.
A lubricant, an antistatic agent, and various other additives can be mixed.

Therefore, this composition is usually used in liquid form. The liquid dispersion medium includes an affinity or water-miscible solvent containing water; water; monohydric alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin; Examples include cyclic alcohols such as benzyl alcohol; cellosolve acetates; ketones and the like.

These may be used alone or in combination, but they can improve the dispersion stability of the composition mainly composed of colloidal silica and/or alumina sol used in the present invention, the wettability after coating on the film surface, and the removal of liquid dispersion medium. It is preferable to decide by taking into consideration the difficulty and economic efficiency.

In addition, this film formed on the surface of the base film generally has a solid content of 0.01 to 10 g/rr.
f, particularly preferably in the range of 0.1 to 5 g/nT.

In order to form a film of an acrylic resin coating composition containing an ultraviolet absorber and an organic nitrogen algaecide on the surface of a base film, and a composition whose main components are colloidal silica and/or alumina sol and a binder, each A solution or dispersion of the composition is applied by a coating method known per se, such as a doctor blade coating method, a roll coating method, a dip coating method, a spray coating method, a rod coating method, a barcoding method, a knife coating method, a brush coating method, etc. In the case of an acrylic resin coating composition, it is necessary to dry it by heating due to the physical properties of the coating, and the drying method after application is drying after application. On the other hand, in the case of a composition containing colloidal silica and/or alumina sol as a main component, either natural drying or forced drying may be employed, and forced drying is preferred. In this case, drying may be carried out at a temperature range of usually 50 to 150°C, preferably 70 to 130"C.

For heat drying, an appropriate method such as a hot air drying method, an infrared drying method, a far infrared drying method, etc. may be adopted, and it is advantageous to adopt a hot air drying method in consideration of drying speed and safety.

Acrylic resin coating composition and colloidal silica and/or
Alternatively, the order in which the coating film of the composition containing alumina sol as a main component is formed on the surface of the base film is determined in consideration of heating conditions and the like.

In addition, if the adhesion between the base film and the coating derived from the two-layer acid compound is not sufficient, the surface of the base film may be cleaned with alcohol or water in advance, or subjected to plasma discharge treatment, corona discharge treatment, or other treatment. Pretreatment such as undercoating with paint or primer may be performed.

Hereinafter, the present invention will be explained in detail based on examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Examples 1 to 4, Comparative Examples 1 to 5 (1) I-body polyethylene terephthalate film lengthwise,
Each side is stretched 3.5 times, and the density is 1.392g/
ai, with a thickness of 125 μm.

(2) Preparation of acrylic resin An acrylic resin for blending the ultraviolet absorber and the organic nitrogen algaecide was prepared as follows.

Methyl methacrylate 45 parts by weight Butyl methacrylate 30 Butyl acrylate
5 〃2-Human Uxyl methyl methacrylate
19 〃Methacrylic acid
1 Isopropyl alcohol 100
A mixture consisting of 1.0 benzoyl peroxide was charged into a polymerization can, and while stirring under a nitrogen gas stream,
After continuing the polymerization reaction at 80"C for 3 hours, 0.5 parts by weight of benzoyl peroxide was added to the same polymerization vessel, and the polymerization reaction was continued for an additional 3 hours at the same temperature. The obtained polymer (resin ) 570 parts by weight of isopropyl alcohol and 60 parts by weight of ethyl acetate were added to the solution to adjust the solid content in the resin solution to 12% by weight.

(3) Formation of a film containing an ultraviolet absorber and an organic nitrogen-based algaecide The acrylic resin solution prepared according to the method described in (2) above is added with the type of ultraviolet absorber shown in Table 1 and an organic nitrogen-based algaecide. The algae agents were each added in the proportions listed in the same table (meaning the proportions relative to the resin solid content).

An acrylic resin coating composition was continuously coated on one side of the base film prepared by the method (1) above by a roll coating method, and held at 100°C for 1 minute in a drying oven to volatilize the solvent. At the same time, heat treatment was performed and each film was wound up. The amount of coating on each film obtained was approximately 2 g/rr
It was f.

(4) Formation of a coating mainly composed of silica and/or acrylic The main components (colloidal silica and/or alumina sol) shown in Table 1, binder component, crosslinking agent, and liquid dispersion medium are mixed and coated. I got a paraboloid.

On the other side of the base film on which the acrylic resin coating was formed, it was continuously coated by the above-mentioned Mi acid roll coating method, and held at 80 ° C for 1 minute in a drying oven to volatilize the liquid dispersion medium. Each film was wound up. The amount of coating on each film obtained was approximately 1 g/rrf.

Outdoor expansion test Nine types of films were installed in a roof-type greenhouse (frontage 3 m, depth 5 m, ridge height 1.5 m) in a test field in Shigun, Mie Prefecture.
m, roof slope of 30 degrees), the acrylic resin coating was placed on the outside of the house, and an expansion test was conducted for 2.5 years from June 1980 to November 1999.

The stretched film was evaluated for algae-proofing properties and dust-proofing properties by the following methods, and the results are shown in Table 2.

Algae resistance: Observation of algae order status with the naked eye.

The evaluation criteria are as follows.

◎...No algae growth is observed on the surface.

○: Slight algae growth is observed on the surface.

△: Considerable algae growth on the surface.

×: Algae has grown and grown over the entire surface.

Dustproof property, meaning the value calculated by the following formula * Direct light transmittance at a wavelength of 555 mμ (newly manufactured by Hitachi, EPS-2U type used) Measurement results were displayed as follows.

◎...The light transmittance after expansion is 90% or more of that before expansion.

O: The light transmittance after expansion is in the range of 70 to 89% of that before expansion.

Δ: The light transmittance after stretching is in the range of 50 to 69% of that before stretching.

×: The light transmittance after stretching is less than 50% of that before stretching.

"Effects of the Invention" The present invention has the following effects, and its agricultural utility value is extremely large.

(1) Even when the agricultural polyethylene terephthalate film according to the present invention is stretched outdoors for a long period of time, the degree of deterioration in algae-proofing and dust-proofing properties is small, and it can be used for a long period of time.

Claims (1)

[Claims] (1) On one side of the polyethylene terephthalate film,
Agriculture in which an acrylic resin film containing an ultraviolet absorber and an organic nitrogen-based algaecide is formed, and a film of a composition containing colloidal silica and/or alumina sol and a binder as main components is formed on the other side of the film. polyethylene terephthalate film.