JPH03234740A - Polyethylene terephthalate film for agricultural use - Google Patents

Abstract

PURPOSE:To prevent the decrease in transparency, accompanying the growth of algae, from occurring when a film is kept spread outdoors and to enhance the persistence of the prevention effect by forming two specific coating films different from each other or both sides, one coating film on one side, of a polyethylene terephthalate film contg. an ultraviolet absorber. CONSTITUTION:On one side of a polyethylene terephthalate film contg. an ultraviolet absorber, an acrylic resin coating film contg. an org. nitrogen algaecide is formed; on the other side a coating film of a compsn. mainly comprising a colloidal silica and/or alumina sol and a binder. The algaecide includes imidazole deriv., anilide deriv., urea deriv., ammonium deriv., and pyridine deriv. The binder includes one having a high affinity with a hydrophilic medium, such as a water or an alcohol which is a dispersion medium of the alumina sol or silica sol, such as, a surfactant or thermoplastic resin with such as affinity.

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.

"Prior Art" In recent years, with the expansion of greenhouse horticulture, the area of facilities has increased, and agricultural polyethylene terephthalate films are increasingly being used in various regions. As the environments in which they are used have become more diverse, the environmental conditions inside and outside the greenhouse have become relatively hot and humid, and algae have grown on the outside or inside of the greenhouse, which is made of polyethylene terephthalate film, 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.

- For boat fishing, algae are microorganisms that exist in surface water, and because they contain chlorophyll, they have the ability to photosynthesize, and the surface is often covered with a sticky substance, so it is difficult to physically prevent the growth of algae on the film. 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 do in large facility houses. It is possible to kill algae by using chemicals such as sodium hypochlorite aqueous solution, but it is necessary to remove the dead algae from the film, and the sustainability of the algaecide effect is limited. cannot be expected for a long time.

"Problems to be Solved by the Invention" Under such circumstances, the present inventors have attempted to prevent the decrease in transparency associated with the growth of algae caused by spreading outdoors, and to
As a result of intensive studies aimed at providing a polyethylene terephthalate film for agricultural use that has excellent long-lasting effects, the present invention has been developed. Agricultural polyethylene terephthalate having an acrylic resin coating containing an organic nitrogen compound formed on one side and a coating of a composition containing colloidal silica and/or alumina sol and a binder as main components on the other side of the film. Exists in 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 the 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 S or O 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 wheel 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 biaxially or horizontally stretched.

The agricultural polyethylene terephthalate film according to the present invention preferably has a thickness of 0.01 to 0.3 mm. If the thickness is less than 0.01+*a+, the strength of the product will not be sufficient, which is undesirable;
Exceeding this is not preferable because the film becomes hard and difficult to handle.

The agricultural polyethylene terephthalate film according to the present invention contains at least an ultraviolet absorber. 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 benzophenone ultraviolet absorber
4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-methoxy-2'-
Carboxybenzophenone, 2,2'-dihydroxy-
4,4'-dimethoxybenzophenone, 2-hydroxy-4-benzoyloxybenzophenone, 2,2'-dihydroxy-4methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfone benzophenone, 2.
2″, 4゜4゛-tetrahydroxybenzophenone, 2
, 2'dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-5-chlorobenzophenone, bis-(2-methoxy-4-hydroxy-5-benzoylphenyl)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-dichlorobenzotriazole, 2-(2'
-Hydroxy-5'-methylphenyl)-5-ethylsulfonebenzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5' -t-
butylphenyl)benzotriazole, 2-(2′-hydroxy-5°-aminophenyl)benzotriazole, 2(2″-hydroxy-3″,5′-dimethylphenyl)benzotriazole, 2-(2″-hydroxy-3 °5 +-dimethylphenyl)-5-methoxybenzotriazole, 2-(2°-methyl-4′-hydroxyphenyl)benzotriazole, 2-(2′-stearyloxy-3′,5′-dimethylphenyl)- 5-
Methylbenzotriazole, 2-(2゜hydroxy-5
-carboxylic acid phenyl)benzotriazole ethyl ester, 2-(2'-hydroxy-3''-methyl-5''-
t-butylphenyl)benzotriazole, 2-(2°
-Hydroxy3″35′-di-t-butylphenyl)-
5-chlorobenzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-
Chlorobenzotriazole, 2-(2″-hydroxy-
5′-Methoxyphenyl)benzotriazole, 2(2
゛-Hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'
-hydroxy-5′-cyclohexylphenyl)benzotriazole, 2-(2″-hydroxy-4′,5′-
dimethylphenyl)-5-carboxylic acid benzotriazole butyl ester, 2-(2'hydroxy-3',5'
-dichlorophenyl)benzotriazole, 2-(2”
-Hydroxy-4''5dichlorophenyl)benzotriazole, 2(2°-hydroxy-3',5'-dimethylphenyl)5-ethylsulfonhencytriazole, 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)penztriazole.

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

These ultraviolet absorbers can be used alone or in combination of two or more, and the amount used is 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, per 100 parts by weight of polyethylene terephthalate.

If the amount used is too small, the desired effect of improving the sustainability of algae control will not be obtained, and if it is too high, the effect of improving the sustainability of algae control will not be seen much compared to the amount used, and the ultraviolet absorber will be damaged by the film. In the present invention, incorporating an ultraviolet absorber into a polyethylene terephthalate film means that the resin composition is added to the polyethylene terephthalate film before film molding. It refers to either a product that has been blended into the base film, a film that has been formed into a film, or a UV absorber that has been applied to the surface of the film after forming the film. A UV absorber may be added to the coating components and applied. These methods can be used alone or in combination.

The agricultural polyethylene terephthalate film according to the present invention has an acrylic resin coating containing an organic nitrogen algaecide formed on one side thereof.

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. The main component is other vinyl monomers that can be copolymerized with these.
Examples include crotonic acid, itaconic acid, acrylonitrile, 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 used by adding compounds such as vinyl chloride/vinyl acetate resin, -vinyl chloride resin, cellulose ether, and the like.

In the present invention, the organic nitrogen algaecide contained in the acrylic resin includes imidazole derivatives such as 2-(4-thiazolyl)-benzikudazole and 2-methoxycarbonylamino-benzimidazole; 3,4.5- Anilide derivatives such as tribromusalicylanilide; urea derivatives such as 3-trifluoromethyl-4,4''-dichloro-N, N'-dichloro-N, N'-biphenylurea; N
-Ammonium derivatives such as ammonium methyldithiocarbamate and tetradecyldimethylbenzylammonium chloride; 2.Pyridine derivatives such as 3,5,6-titrachloro-4(methylsulfonyl)pyridine; 2-
Triazine derivatives such as methylthio-4-tert-butylamino-6-cyclopropyl-amino-s-triazine; N- such as N,N-dimethyl-N'-(fluorodichloromethylthio)-N'-phenylsulfamide; Haloalkylthio derivatives; Phthalimide derivatives such as N-(fluorodichloromethylthio)-phthalimide and N-1,1,2,2-tetrachloroethylthiotetrahydrophthalimide; 2.4,5.6 tetrachloroisoaphthalonitrile, etc. Nitrile derivatives such as; benzothiazole derivatives such as 2-(4-thiothio)benzothiazole; 4-substituted benzylamine derivatives such as 4-trimethylsilylbenzylamine; dithiocarbamate derivatives such as tetramethylthiuram disulfide. I can do it. These organic nitrogen-based algaecides may be used alone or in combination of two or more. Furthermore, if necessary, an algaecide other than organic nitrogen type, such as parachloromethaxylenol, may be used at the same time.

If the amount of the organic nitrogen algaecide added to the acrylic resin is too small, the object of the present invention will not be achieved, and if it is too large, the transparency of the film formed on the film will decrease, causing problems. be.

The preferred blending amount is in the range of 0.1 to 50 parts by weight per 100 parts by weight of the acrylic resin. Among these, it is particularly preferable that the amount is in the range of 0.5 to 30 parts by weight per 100 parts by weight of the acrylic resin.

A liquid dispersion medium may be further added to the above composition as required. Such liquid dispersion media include monohydric alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; polyhydric alcohols such as ethylene glycol; cyclic alcohols such as dibenzyl alcohol; cellosolve acetates; acetic acid esters; aliphatic Examples include 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 coating Mi, the wettability after coating on the film surface, the difficulty of removing the liquid dispersion medium, and economic efficiency.

The above composition may further include an antifoaming agent, a surfactant, a lubricant, an antistatic agent, a plasticizer, an antioxidant, a crosslinking agent, an ultraviolet absorber, a light stabilizer, a film forming aid, and a thickening agent, as necessary. , pigments, 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 generally has a solid content of 0.1 to 10 g/
In particular, it is preferably in the range of 0.5 to 5 g/bo.

Agricultural polyethylene terephthalate 1-1 according to the present invention
1ALLfl mayo+v1ノh+'+1. ,',! Word-a
, TL F-e/or a film of a composition whose main components are alumina sol and a binder is formed. Since the film derived from this film has moisture absorption and water absorption properties, it is less effective in removing moisture that causes algae growth inside and outside the house, and therefore improves the algae-proofing properties of the hydrophobic polyethylene terephthalate film.

The colloidal silica and/or alkaline silica preferably has an average particle diameter of 5 to 100 mμ. If the average particle diameter exceeds Loomμ, 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. Further, when used alone or in combination, two or more types having different average particle diameters may be used in combination. When combining the two,
Colloidal silica/alumina sol weight ratio is 95-51
Preferably, the ratio is between 5 and 95 (total 100).

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.

It is preferable that the blending amount of Minazol is in the range of 0.5 to 40 times the weight of the binder component in terms of solid content weight ratio. 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. Also,
The paint film tends to become rough and brittle. On the other hand, 0
．． When it is less than 5 times, it becomes difficult to exhibit sufficient moisture absorption and water absorption effects.

This composition may also contain a crosslinking compound that crosslinks the binder components. By doing so, the water resistance of the film can be improved.

The amount of the crosslinking compound used is in the range of 0.1 to 30% by weight, particularly 0.5 to 10% by weight based on the solid content of the binder component.
A range of is preferred.

In addition, if necessary, antifoaming agents,
A lubricant, an antistatic agent, and various other additives can be mixed.

Ru. 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;
Examples include polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin; cyclic alcohols such as benzyl alcohol; cellosolve acetates; and ketones.

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.
T, particularly preferably in the range of 0.1 to 5 g/rrr.

To form a film of an acrylic resin coating composition containing an organic nitrogen-based algaecide and a composition containing colloidal silica and/or aldanazole and a binder as main components on the surface of the base film, generally each composition is Apply the solution or dispersion using a coating method known per se, such as a doctor blade coating method, roll coating method, dip coating method, spray coating method, rod coating method, barcoding method, knife coating method, or dip coating method. Just dry it afterwards. Regarding the drying method after application, in the case of an acrylic resin coating composition containing an organic nitrogen-based algaecide, it is necessary to dry by heating due to the physical properties of the coating, and the heating temperature is 50 to 200°C for 5 seconds to 10 minutes. 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 used.
When using forced drying method, usually 50-150'C
1. It is preferable to dry at a temperature range of 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.

The order in which the coating film is formed on the surface of the base film by the acrylic resin coating composition containing the organic nitrogen algaecide and the composition mainly composed of colloidal silica and/or alumina sol is determined by taking into account the heating conditions, etc. .

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 brimer may be applied.

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) Preparation of base film Polyethylene terephthalate (intrinsic viscosity measured at 25 °C using O-chlorophenol as a solvent is 0.6
5) to 100 parts by weight of the ultraviolet absorbers shown in Table 1 in the proportions shown in the same table, the respective formulations were stirred and mixed in a super mixer for 10 minutes, then melt-extruded by a conventional method, and vertically Stretching temperature 65°C5 Stretching ratio 3.5 times,
Then, the film was successively biaxially stretched in the transverse direction at a stretching temperature of 65°C and a stretching ratio of 3.5 times to produce a biaxially oriented film with a thickness of 0.15 mm. The density of this film was 1.37 g/cd.

(2) Preparation of acrylic resin The acrylic resin used to formulate the organic nitrogen algaecide is
It was prepared as follows.

Methyl methacrylate 45 parts by weight Butyl methacrylate 30 Butyl acrylate
5 〃2-Hydroxyethyl methacrylate 19 〃Methacrylic acid
1 Isopropyl alcohol 1
A mixture consisting of 1.0% benzoyl peroxide was added for each polymerization, and the polymerization reaction was continued for 3 hours at SO'C while stirring under a nitrogen gas stream.
．． 5 parts by weight were added, and the polymerization reaction was continued for an additional 3 hours at the same temperature. The resulting polymer (resin)? 570 parts by weight of isopropyl alcohol and 60 parts by weight of ethyl acetate were added to liquid No. 8 to adjust the solid content in the resin solution to 12% by weight.

(3) Formation of film containing organic nitrogen-based algaecide
The types of organic nitrogen algaecides shown in the table were added in the proportions (meaning the proportions relative to the resin solid content) shown in the table.

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 the solvent was volatilized by holding it in a drying oven at 100"C for 1 minute. Heat treatment was performed at the same time, and each film was wound up.The amount of coating on each film obtained was approximately 2 g/nf.
Met.

(3) Formation of a film mainly composed of silica and/or acrylic An antifogging agent is formed by blending the main components (colloidal silica and/or alumina sol) shown in Table 1, a binder component, a crosslinking agent, and a liquid dispersion medium. I got something.

The above composition was continuously applied by roll coating to the other side of the base film on which the acrylic resin coating had been formed, and held in a drying oven at 80'C for 1 minute to volatilize the liquid dispersion medium. I wound it up. The amount of coating on each film obtained was approximately 1 g/bo.

Outdoor expansion test Nine types of films were installed in a roof-type greenhouse (3 m wide, 5 m deep, 1.5 m high) in a test field in Shigun, Mie Prefecture.
, a roof slope of 30 degrees) was coated with the surface on which the coating was provided facing the outside of the house, and an expansion test was conducted for 2.5 years from May 1988 to October 1988.

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 growth with the naked eye.

The evaluation criteria are as follows.

thing.

Δ: Significant algae growth is observed on the surface.

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

Dustproof property: means a value calculated using the following formula.

* Direct light transmittance at a wavelength of 555 mμ (using a new model made by Hitachi Seisakusho, EPS-2U model) The measurement results were displayed as follows.

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

○...The light transmittance after stretching is in the range of 70 to 89% of that before stretching.

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

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

Table 2 "Effects of the Invention J 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) An acrylic resin film containing an organic nitrogen algaecide is formed on one side of a polyethylene terephthalate film containing an ultraviolet absorber, and a film containing colloidal silica and/or alumina sol and a binder as main components is formed on the other side of the film. An agricultural polyethylene terephthalate film formed with a coating of a composition.