JPS6153038A - Agricultural polyethylene terephthalate 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 [Field of the Invention] The present invention relates to a polyethylene terephthalate film for agricultural use. More specifically, the present invention relates to an agricultural polyethylene terephthalate film having excellent mechanical strength, excellent weather (light) resistance, and excellent antifogging properties.

"Prior Art" In general, polyethylene terephthalate film exhibits high crystallinity, high melting point, heat resistance and chemical resistance, and also exhibits excellent mechanical properties such as strength and elastic modulus. Are known. For this reason, polyethylene terephthalate films are widely used for magnetic tapes, photography, electricity, metallization, packaging, agriculture, and the like. However, this film has the property of absorbing ultraviolet rays, especially the ultraviolet rays of 320 na+ or less, and has the disadvantage that its mechanical properties deteriorate severely if it is extended outdoors for a long period of time. .

In order to improve the weather resistance of this film, the film was made after adding an ultraviolet absorber, and
As described in Japanese Patent No. 60, a method is known in which an ultraviolet absorber is tightly bonded to the film surface. In the former method, the UV absorber is uniformly mixed and dispersed in the resin. However, according to these methods, harmful light rays are gradually dispersed as they pass through the film from the incident side to the opposite side. Although it is absorbed and weakened, the side of the film where the light rays enter will be harmed by the harmful rays, and the weather resistance of the film cannot be sufficiently improved. Although the latter method can produce a film that exhibits better weather resistance than the former method, it is difficult to bond the ultraviolet absorber firmly to the film surface at a uniform concentration, and the film cannot be used outdoors for long periods of time. It has been difficult to impart sufficient weather resistance to withstand stretching and outdoor exposure.

On the other hand, polyethylene terephthalate film has a hydrophobic surface, so when it is used as a covering material for an agricultural greenhouse (greenhouse), depending on conditions such as temperature and humidity inside the greenhouse, the surface of the film on the house side may Causes cloudiness.

This haze reduces the amount of light that passes through the film,
This can cause various inconveniences, such as slowing down plant growth, causing water droplets to fall on cultivated plants, damaging young buds, causing disease, and causing discomfort to workers in the greenhouse. occurs.

It is known that in order to eliminate such inconveniences, it is sufficient to impart antifogging properties to the surface of the film. To impart antifogging properties to the film surface, (a) A method of kneading a hydrophilic substance such as a surfactant into the base synthetic resin material to form an film.

(b) A method of applying a water-soluble polymer to the surface of the film.

(c) A method of applying a water-soluble polymer to the surface of the film and further crosslinking it.

etc. are known. However, method (a) is difficult to apply to hard resins such as polyethylene terephthalate. Method (b) has the disadvantage that the water-soluble polymer is easily washed away by water, and the antifogging property does not last for a long time. Method (c) requires complicated steps and is not a preferable method.

[Before the problem that the invention sought to solve] Under such circumstances, the present inventors have discovered that the invention does not reduce its mechanical strength even when used for a long period of time as a house covering, and exhibits excellent weather (light) resistance. In order to provide an agricultural polyethylene terephthalate film that maintains excellent antifogging properties for a long period of time, the present invention has been completed as a result of intensive studies.

Means for Solving Problem F"The gist of the present invention is that the thickness of 0.1 to 0.31
11 m of agricultural polyethylene terephthalate film with a thickness of 1 to 100 ft with a UV absorber blended on one side.
An acrylic resin coating of 10 microns is formed on the other side, and an antifogging coating containing alumina sol, silica sol, and nonionic surfactant as active ingredients with an average particle size of 100 millimicrons or less is formed on the other side. An agricultural polyethylene terephthalate film characterized by:

The present invention will be explained in detail below.

The polyethylene terephthalate referred to in the present invention includes not only non-copolymerized polyethylene terephthalate homopolymer, but also copolymerized polyethylene in which 85% or more of the repeating units are polyethylene terephthalate units and the remainder is other components. Polymer blends include terephthalate and polyethylene terephthalate in an amount of 85% by weight or more and the remaining 15% by weight or less of other polymers. Other polymers that can be blended include polyamides, polyolefins, and other types of polyesters. This polyethylene terephthalate may be blended with some amount of lubricant, colorant, stabilizer, antioxidant, etc., if necessary.

The agricultural polyethylene terephthalate film according to the present invention is biaxially stretched.

The method for producing a biaxially stretched film is not particularly limited, and any known method may be employed, such as sequentially or simultaneously biaxially or horizontally stretched.

The agricultural polyethylene tereftate film according to the present invention is biaxially stretched by 2.0 to 5.0 times. 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 manufacturing work will be difficult. Therefore, it is not desirable. The stretching ratio is
Particularly preferred is a range of 2.5 to 4.0 times in both directions.

The agricultural polyethylene terephthalate film according to the present invention preferably has a thickness of 0.01 to 0.31 DI11. If the thickness is less than 0.01+on+, the strength of the product will not be sufficient, which is undesirable.
If it exceeds fi, the film becomes hard and difficult to handle, which is not preferable.

The agricultural polyethylene terephthalate film according to the present invention has an acrylic resin coating containing an ultraviolet absorber on one side.

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 copolymers made of two 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, itafonic acid, acrylonitrile,
Styrene, vinyl chloride, hydroxyalkyl (meth)acrylate, etc. can be used.

The types of ultraviolet absorbers to be added to these acrylic resins include conventionally known ultraviolet absorbers such as salicylic acid compounds, benzophenone compounds, benzotriazole compounds, and the like. Among these, when evaluated from the viewpoints of solubility in acrylic resins, weather resistance when applied to polyethylene terephthalate film for agricultural use, etc., 2,4-dihydroxybenzophenone, 2, of the benzophenone compounds -Hydroxy-4-nodoxybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone are preferred, and among benzotriazole compounds, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole is particularly preferred. preferable. These may be used alone or in combination of two or more.

The amount of ultraviolet absorber blended into the acrylic resin is:
If it is too small, the object of the present invention will not be achieved, and if it is too large, there will be a problem of bleed-out. The preferred blending amount is acrylic fruit tree [1 ton, 100 parts by weight]
It ranges from 0 to 25 parts by weight.

If the thickness of the acrylic resin film containing these ultraviolet absorbers is too thin, the object of the present invention will not be achieved, so it is not preferable, and if it is too thick, the problem arises that the film is likely to peel off.

The thickness of the coating is preferably in the range of 1 to 10 μm, particularly in the range of 1 to 10 μm.
A range of 5μ is preferred.

The amount of ultraviolet absorber blended into the acrylic resin and the thickness of the film formed on one side of the polyethylene terephthalate can be varied, but the amount of ultraviolet absorber that appears per constant area of the film is 150 to 150 b. The agricultural polyethylene terephthalate film according to the invention has an antifogging coating formed on the other side thereof, the active ingredients being alumina sol, silica sol, and a nonionic surfactant having an average particle size of 100 millimicrons or less.

Alumina sol and silica sol, which are the active ingredients of the anti-fog coating, function to improve the anti-fogging properties of the film surface and improve the durability of the anti-fogging properties, while nonionic surfactants serve to improve the anti-fogging properties of the coating. .

The average particle diameter of the alumina sol and silica sol is 100 millimicrons or less. If it is larger than 100 millimicrons, the antifogging coating containing this decreases the transparency of the film, which is not preferable.

Alumina sol and silica sol have a solid content weight ratio of 80
A mixture of 20/20 to 80 (total 100) is preferable. Alumina sol is effective in improving wetting of the film surface by moisture, but if the proportion of this component increases, the anti-fog durability of the anti-fog coating will deteriorate, and the anti-fogging composition that forms this coating will deteriorate. This is not preferable because the fluidity of the material also deteriorates. Silica sol is effective in improving the antifogging durability of the antifogging film, but if the proportion of this component increases, it is not preferable because the wetting of the film surface by moisture becomes poor. In order to improve the moisture wetting of the antifogging film and maintain the antifogging effect, it is preferable that the mixing ratio of alumina sol and silica sol be within the above range.

To form an antifogging film on the other side of the polyethylene terephthalate film, the above alumina sol and silica sol are dispersed in water together with a nonionic surfactant to be described later to form an antifogging agent composition, and this is applied. All you have to do is let the moisture evaporate.

The proportion of alumina sol and silica sol in the antifogging agent composition is preferably 1 to 40% by weight.

When these proportions are less than 1% by weight, the antifogging agent composition contains too little active ingredient, which is undesirable. On the other hand, when it exceeds 40% by weight, the viscosity of the antifogging agent composition becomes too high, which is not preferable. do not have. Particularly preferred within the above range is 15
-30% by weight.

The alumina sol may be a commercially available product itself, or an aqueous sol prepared by dispersing commonly available alumina powder in water. When alumina sol is dispersed in water at a high concentration, it exhibits so-called thixotropy, in which the viscosity of the dispersion increases rapidly. By using this, a homogeneous dispersion can be obtained.Also, by mixing silica sol with this dispersion, the viscosity of the dispersion can be lowered.

On the other hand, in most cases, the particle surface of silica sol is
Although it is negatively charged, in the present invention,
It is not preferable to use a material that is negatively charged.

This is because the above-mentioned alumina sol has a positively charged particle surface, so when a negatively charged silica sol and a positively charged alumina sol are mixed, the mixed dispersion rapidly aggregates. It gels and causes poor dispersion.

Therefore, it is preferable that the silica sol has a positively charged particle surface.

The antifogging agent composition for forming the antifogging film contains 0.05 to 15% of a nonionic surfactant (the entire antifogging agent composition is 100% by weight).

The amount of nonionic surfactant in the antifogging agent composition is 0.0
When the amount is less than 5% by weight, the dispersion stability of the antifogging agent composition is poor, and the efficiency of coating the film surface is poor, and
It is not preferable because it does not improve the antifogging properties after application.

On the other hand, when it exceeds 15%, the antifogging agent composition has poor dispersibility, poor fluidity (high viscosity), and poor antifogging durability, which is not preferable. Particularly preferred within the above range is 0.1 to 8% by weight.

-12= Specific examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, and fatty acids. Examples include alkylolamides and cellulose ethers.

The antifogging agent composition for forming the antifogging film contains water. This water functions as a medium for dispersing the alumina sol, silica sol, and nonionic surfactant. This amount of water can be used for alumina sol, silica sol,
The total amount of nonionic surfactant and water is preferably 100% by weight.

The antifogging agent composition for forming the antifogging film contains the three components of alumina sol, silica sol, nonionic surfactant, and water as described above. For the purpose of adjusting the fluidity of the antifogging agent composition, a small amount of monovalent inorganic acid or organic acid may be included as a fourth component.

The antifogging agent composition for forming the above antifogging film is applied as it is or diluted with water to the surface of the film to which you want to impart antifogging properties, and when the water is evaporated, an inorganic substance is formed on the film surface. An antifogging film made of colloidal sol particles and a nonionic surfactant is formed. This anti-fog coating exhibits excellent anti-fog properties and maintains this for a long period of time.

To produce the agricultural polyethylene terephthalate film according to the present invention, first, a biaxially stretched polyethylene terephthalate film is produced. Next, a solution of an acrylic resin and an ultraviolet absorber dissolved in an inert organic solvent such as isopropyl alcohol is applied to one side of this biaxially stretched polyethylene terephthalate film, and the organic solvent is evaporated to absorb ultraviolet light. Forms an acrylic resin film containing the agent. Suitable coating methods include commonly used gravure coating methods, reverse coating methods, spray methods, and the like. Subsequently, the composition for forming the antifogging film is applied to the other side of the film. Application methods include roll coating, dip coating,
A method known per se, such as a brush coating method or a knife coating method, can be used.

The acrylic resin coating and antifogging agent composition applied to the surface of the film may be dried by a natural drying method or a forced drying method. When forced dry, hot air drying method,
Infrared irradiation method etc. can be adopted.

The anti-fog coating formed on the other side of the film has a solid content of 0.001 to 1.5 g/111 per unit area.
About 2 is enough, especially 0.005 to 0.75g/l11
It is preferable to set it in the range of 2.

Note that it is preferable to modify the surface of the polyethylene terephthalate film on which the acrylic resin coating is to be formed by subjecting the film surface to plasma treatment or corona discharge treatment. In addition, the surface on which the antifogging film is to be formed may be subjected to an undercoat treatment (for example, as described in Japanese Patent Publication No. 50-5733, a coating agent mainly composed of acrylic resin may be applied). Method), it is preferable to modify the surface of the film by subjecting it to plasma treatment or Rona discharge treatment.

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

FIG. 1 is a sectional view of an example of an agricultural polyethylene terephthalate film according to the present invention.

In the figure, 1 is a polyethylene terephthalate film, 2 is an ultraviolet Is@acrylic resin coating, and 3 is an antifogging coating.

When the agricultural polyethylene terephthalate film according to the present invention is actually used as a coating material for a greenhouse, the surface on which the ultraviolet absorber-containing acrylic resin coating 2 is formed is the outside, and the antifogging coating 3 is Use the formed surface as the inside. "Effects of the Invention" 16. The agricultural polyethylene terephthalate film according to the present invention has the following particularly remarkable effects, and its industrial utility value is extremely large.

(1) The agricultural polyethylene terephthalate film according to the present invention has excellent adhesion between the polyethylene terephthalate film and the acrylic resin coating, and combined with the fact that this coating is extremely thin, the coating does not peel off.

(2) The acrylic resin film formed on one side of the polyethylene tele-7 tallate film according to the present invention does not bleed even if it contains a large amount of ultraviolet absorber compared to other resin films.
It is suitable for forming coatings containing ultraviolet absorbers as there is little problem of outflow.

(3) The coating made of acrylic aluminum resin formed on one side of the polyethylene terephthalate film according to the present invention has excellent weather resistance in itself, so it is difficult to be deteriorated by ultraviolet rays, which may adversely affect the base polyethylene terephthalate film. There is no fault.

(4) Due to its characteristics, the film made of acrylic resin is non-sticky and has little dust adhesion, contributing to maintaining transparency and transmittance for a long period of time. suitable for

(5) The antifogging coating formed on the other surface of the polyethylene terephthalate film according to the present invention contains alumina sol and silica sol of specific particle sizes, and a nonionic surfactant as active ingredients, so the film It also shows excellent surface wettability (anti-fog properties) and durability of anti-fog effects.

[Examples] 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 6 (1) Base polyethylene terephthalate film stretched 3.5 times lengthwise and widthwise, and has a density of 1.392
g7am2, thickness 125μ.

(2) Preparation of acrylic resin The acrylic resin solution for blending the ultraviolet absorber is
It was prepared as follows.

1) Preparation of acrylic resin solution A (a) Production of crosslinked elastic body During polymerization, 300 parts by weight of deionized water (hereinafter simply referred to as "part E" means "parts by weight"), 0.3 parts of potassium persulfate, 0.5 parts of disodium phosphate dodecahydrate, and 0.3 parts of sodium hydrogen phosphate dihydrate were charged, and after sufficient nitrogen substitution, the internal temperature was raised to 70°C. . While maintaining the internal temperature at this temperature and stirring, a mixture of 19.8 parts of styrene, 69.3 parts of butyl acrylate, 0.9 parts of allyl methacrylate, and 2.5 parts of sodium dioctylsul-7-ocuccinate (emulsifier) was added. The mixture was added continuously over a period of 2 hours. 'Immediately after the addition, add 1.0 part of t-butylperoxy-2-ethylhexanoate and 2 parts of styrene.
．． A mixture consisting of 2 parts, 7.7 parts of butyl acrylate, and 0.1 part of allyl acrylate was added. 30 minutes after adding
After a minute had elapsed, the internal temperature was raised to 90°C, and the reaction was continued at this temperature for 3 hours to obtain an emulsion of crosslinked elastic material.

The average particle diameter of this crosslinked elastic body was 0.20 microns, the gel content was 97.1%, and the degree of swelling was 7.2.

(b) Production of graft copolymer Place the crosslinked elastomer emul 7524 obtained in (a) above in a polymerization can.
After 00 parts of the mixture was charged and the mixture was replaced with nitrogen while stirring, the internal temperature was raised to 80°C. While maintaining the internal temperature at this temperature, a solution of 0.15 parts of sodium 7-olmaldehyde sulfoxylate dissolved in 3.0 parts of deionized water was added with stirring, and then 30.0 parts of methyl methacrylate, n - A mixture of 0.03 parts of lactyl mercaptan and 0.15 parts of para-menthane hydroperoxide (50% solution) was added continuously over a period of 30 minutes. After the addition was completed, the polymerization reaction was continued for another 30 minutes to obtain a graft copolymer emulsion.

The obtained graft copolymer emulsion was salted out according to a conventional method, the polymer was separated by filtration, washed with water,
After drying, a graft copolymer powder was obtained.

(c) 6.5 parts of the graft copolymer obtained in the preparation of resin solution A was mixed with methacrylic resin (methyl methacrylate/ethyl methacrylate in a ratio of 96/4
13.5 parts of copolymer beads with a ratio of % acrylic resin solution A was prepared.

2) Preparation of acrylic resin solution Bf (a) Production of crosslinked elastic body During the polymerization, 250 parts of deionized water, 2.0 parts of sodium dioctyl sulfosuccinate, and 7 parts of sodium olmaldehyde sulfoxylene were added. While stirring the contents of this polymer fabric, 1.6 parts of methyl methacrylate, 8 parts of butyl acrylate, 0.4 parts of 1.3-butylene dimethacrylate,
A mixture consisting of 0.1 part of allyl methacrylate and 0.04 part of cumene hydroperoxide was charged.

The internal temperature of the polymer fabric was raised to 70°C, and the reaction was continued at this temperature for 60 minutes. Subsequently, 1.5 parts of methyl methacrylate, 22.5 parts of butyl acrylate, 1.0 part of 1,3-butylene dimethacrylate, and 0 parts of allyl methacrylate were added to the polymer fabric.
．． A mixture of 25 parts and cumene hydroperoxide in an amount of 0.05% by weight based on the monomer mixture was added over a period of 60 minutes.

The obtained crosslinked elastic body had an average particle size of 0.12 microns, a gel content of 90%, and a swelling degree of 1.
It was 0.

(1) In the polymer fabric containing the crosslinked elastomer emulsion of (a) in the production of the graft copolymer,
Add a solution of 0.01 parts of sodium 7-olmaldehyde sulfoxylate dissolved in 3 parts of ionized water, then add 5 parts of methyl methacrylate, 5 parts of butyl acrylate, 0.1 part of allyl acrylate, and these monomers. For o. 03
A mixture of cumene hydroperoxide in an amount of % by weight was added continuously over a period of 30 minutes. After the addition was completed, the polymerization reaction was continued for an additional 30 minutes.

To this polymer fabric, add 3 parts of ionized water, 7 parts of sodium olemaldehyde sulfoxylate) 0.05
A mixture of 52.25 parts of methyl methacrylate, 2.75 parts of butyl acrylate, and 0.13 parts of para-menthane hydroperoxide (50% solution) was added. was added over a period of 30 minutes. After this addition was completed, the polymerization reaction was continued at 80° C. for 30 minutes to obtain a graft copolymer emulsion.

The obtained graft copolymer emulsion was salted out according to a conventional method, the polymer was separated by filtration, washed with water,
After drying, a graft copolymer powder was obtained.

(c) 20 parts of the graft copolymer obtained in the preparation of resin solution B was placed in a mixed solvent consisting of 64 parts of methyl ethyl ketone and 16 parts of toluene and stirred to obtain an acrylic resin solution with a solid content of 20% by weight. B was prepared.

(3) Formation of UV absorber-containing film Add the type of UV absorber shown in 1 of Table 1 to the acrylic resin solution prepared according to the method described in (2) above.
It was added at the ratio (meaning the ratio to the resin solid content) listed in the same table. The solution after addition was applied to one side of a polyethylene terephthalate film by a gravure coating method, and the applied surface was heated to volatilize the solvent to form a film containing an ultraviolet absorber. The thickness of this coating and the amount of ultraviolet absorber per unit area of the film are shown in Table 1.

(4) Preparation of antifogging agent composition An antifogging agent composition for forming an antifogging film was prepared as follows.

1) Preparation of antifogging agent composition a (a) Preparation of alumina sol While stirring water in a container, aluminum oxide C (manufactured by Nippon Aerosil Co., Ltd., average particle size 20 mm) was added to reduce the solid content. 25% by weight
A dispersion was prepared. During the process of preparing this dispersion liquid, the viscosity increased, so nitric acid was added while stirring the dispersion liquid to adjust the pH of the liquid to 4.3.

(mouth) Preparation of antifoaming agent liquid While stirring the water in the container, add a silicone emulsion (manufactured by Toshi Silicone Co., Ltd., S M
5512 (solid content: 45% by weight) was added to prepare a silicone emulsion (antifoaming agent liquid) with a solid content of 10% by weight.

(c) Preparation of antifog composition a 15 g of water was added to 60 g of the alumina sol dispersion prepared in (a) above. While stirring this solution, a positively charged silica sol (manufactured by Nissan Chemical Co., Ltd., Snowtex AK, solid content 25% by weight, average particle size 15
20 grams of polyoxyethylene sorbitan monolaurate (manufactured by NOF Corporation, nonionic surfactant, trade name LT-221), and the antifoam prepared in (b) above. One gram of the agent solution was added to obtain antifogging agent composition a.

2) Preparation of antifogging agent composition (a) Preparation of methylcellulose dispersion While stirring water in a container, add methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., nonionic surfactant, trade name Metrose 8M-). 15) and 10
A weight percent dispersion was prepared.

(b) Preparation of antifogging agent composition 9 grams of water was added to 60 grams of the alumina sol dispersion prepared in step (a) of the preparation process of antifogging agent composition a. While stirring this solution, add 20 grams of silica sol (Snowtex AK), 10 grams of the methylcellulose dispersion prepared in (a) above, and the antifogging agent prepared in step (b) of the preparation process of antifogging agent composition a. One gram of foaming agent liquid was added to obtain an antifogging agent composition.

3) Preparation of antifogging agent composition C 115 grams of water was added to 20 grams of the alumina sol dispersion prepared in step (a) of the preparation process of antifogging agent composition a. While stirring this liquid, 60 grams of silica sol (Snowtex AK), 4 grams of polyoxyethylene sorbitan monolaurate (LT-221), and the preparation process (b) of the preparation process of antifogging agent composition a were added. One gram of antifoaming agent liquid was added to obtain antifogging agent composition C.

(5) Formation of antifogging film Three types of antifogging agent compositions prepared according to the method described in (4) above were each diluted 150 times with water to prepare three types of coating solutions.

Each of these coating liquids was applied to a polyethylene terephthalate film by a spray coating method, and the solid content after drying was adjusted to 0.25 g/l12.

(6) Properties of the film before outdoor exposure A polyethylene terephthalate film that has a coating containing an ultraviolet absorber on one side and an anti-fog coating on the other side should have the following properties before being exposed outdoors. It was measured. The results are shown in 2 of Table 1.

1) Light transmittance spectrophotometer at wavelength 340rv+ (
Measurements were made using a new model 323 manufactured by Hitachi.

2) Growth rate Compliant with JIS K-6234.

3) Puncture Impact Strength A sample with a length of 10 cm and a width of 10 c+a was tested using a puncture impact test ff1 (newly manufactured by Toyo Seiki Seisakusho), and the energy at breakage was expressed in kg/ell.

4) Light transmittance at a wavelength of 550 nm Same as in case 1).

(7) Characteristics of films after outdoor exposure The six types of films according to the examples were tested on the roofs of open-and-close greenhouses from August 1980 to July 1980 in a field in Yatabe-cho, Tsukuba-gun, Ibaraki Prefecture. The following properties were measured on the film after coating and exposure. The results are shown in 3 of Table 1.

The elongation rate, buncher impact strength, and light transmittance at a wavelength of 550 nm are the same as in (6) for evaluating the properties of the film before outdoor exposure.

For each film, immediately after exposure, after one month,
At each time point after 6 months had elapsed, the antifogging properties of the film were visually observed. The results are shown in 3 of Table 1.

The evaluation criteria for antifogging properties were as follows.

rlJ--Good anti-fogging property r2J--Slightly poor view-proofing r3J--Poor anti-fogging property [Comparative example] Comparative example 1 A base polyethylene terephthalate film having the same properties as that used in Example 1 was used. For those that do not form an acrylic resin film or an anti-fog film, as in Example 1, various properties of the film were measured before outdoor exposure, and the film was further exposed outdoors in the same manner as in the same example.
- Various properties of the film were measured after being exposed outdoors.

The results are shown in 1.2.3 of Table 1.

Comparative Example 2 A film of acrylic resin solution A containing no ultraviolet absorber was formed on one side of a base polyethylene terephthalate film having the same properties as those used in Example 1. However, no antifogging film was formed on other surfaces.

Regarding this film, as in Example 1, various properties were measured on the film before outdoor exposure, and then the film was exposed outdoors in the same manner as in the same example, and various properties were measured on the film after outdoor exposure. did. The results are shown in Table 1.
．． Shown in 2.3.

Comparative Example 3 To 100 parts by weight of raw material polyethylene tele7 turret, 2
- 0.34 parts by weight of (2'-hydroxy-5'-tert-butylphenyl)benzotriazole was blended.

This mixture was formed into a film by a known method, stretched 3.5 times in both length and width, and had a density of 1.392 g/
A film of am3 and thickness of 125 μm was obtained. Neither an acrylic resin coating nor an antifogging coating was formed on this film.

Regarding this film, as in Example 1, various properties were measured on the film before outdoor exposure, and then the film was exposed outdoors in the same manner as in the same example, and various properties were measured on the film after outdoor exposure. did. The results are shown in Table 1.
．． Shown in 2.3.

Comparative Example 4 A polyethylene terephthalate film surface-treated with an ultraviolet absorber (LLuIIl) sold by Martin Processing Company, Inc.
ar, thickness 125 μm), various properties were measured on the film before outdoor exposure, as in Example 1. Furthermore, the film was exposed outdoors in the same manner as in the same example, and various properties of the film after outdoor exposure were measured. The results are shown in 1.2.3 of Table 1.

Comparative Example 5 A film prepared in the same manner as in Example 2 except that an anti-fog coating was not formed on the other surface of the film.

The properties of this film were evaluated in the same manner as in the same example. The results are shown in 1.2.3 of Table 1.

Comparative Example 6 In the film of Example 2, a composition not containing alumina sol (b) was prepared in the example described in the preparation method of antifogging agent composition a, and a film was formed by the same procedure as in the same example. A film was otherwise prepared in the same manner as in the same example.

The properties of this film were evaluated in the same manner as in the same example. The results are shown in 1.2.3 of Table 1.

111) in Table 1 means 2-(2'-hydroxy-5'-1-butylphenyl)benzotriazole.

Y means ethyl-2-cyano-3,3-diphenyl acrylate.

*2a'' means a excluding alumina sol.

2 of Table 1 3 in Table 1 From 1.2.3 of Table 1, the following becomes clear.

(1) Even when the agricultural polyethylene terephthalate film according to the present invention is exposed outdoors, it is hardly affected by ultraviolet rays, and there is little decrease in elongation and impact strength. In contrast, those to which no ultraviolet absorber was added (
Comparative Examples 1 and 2), those in which a UV absorber was added and formed into a film (Comparative Example 3), and those in which an ultraviolet absorber was tightly bonded to the film surface (Comparative Example 4) showed a significant decrease in impact strength.

(2) The agricultural polyethyl ntele 7 tallate film according to the present invention has almost no change in transparency even when exposed outdoors. On the other hand, did you not add UV absorbers? ) (Comparative Example 1) was added to form a fillerem (Comparative Example 3), the transparency was significantly reduced.

(3) The agricultural polyethylene terephthalate film according to the present invention has excellent film surface wettability (antifogging properties),
It also has an excellent long-lasting anti-fog effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an example of an agricultural polyethylene terephthalate film according to the present invention. In the figure, 1 is a polyethylene terephthalate film, 2 is an acrylic resin coating containing an ultraviolet absorber, and 3 is an antifogging coating. Applicant Sanbao Monsanto Kawei Vinyl Co., Ltd. Agent
Patent Attorney Hase - (1 other person) Illustration of a falcon

Claims (1)

[Claims] (1) An agricultural polyethylene terephthalate film with a thickness of 0.1 to 0.3 mm that has been stretched 2.0 to 5.0 times in each biaxial direction, with a UV absorber blended on one side. An acrylic resin film of 1 to 10 microns is formed on the other side, and the average particle size is 100 microns.
An agricultural polyethylene terephthalate film characterized by forming an antifogging film containing a millimicron or smaller alumina sol, silica sol, and a nonionic surfactant as active ingredients.