JPH115284A - Agricultural polyethylene terephthalate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agricultural polyethylene terephthalate film of superior weather resistance and transparency and also of superior scuffing resistance of film and blocking resistance after storing the film for a long period of time. SOLUTION: In a polyethylene terephthalate film on which an acrylic resin film containing acrylic resin and an ultraviolet absorbent of 1-40 pts.wt. to acrylic resin of 100 pts.wt. and spherical fine particles are formed on one face of a polyethylene terephthalate film oriented in the biaxial direction, the average particle diameter of spherical particles is 0.05 or more to three times or less of the thickness of a film formed on the assumption of excepting the spherical fine particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an agricultural polyethylene terephthalate film. More specifically, it has excellent weather resistance and transparency, and has excellent scratch resistance of the coating and blocking resistance after long-term storage,
The present invention relates to an agricultural polyethylene terephthalate film.

[0002]

2. Description of the Related Art In general, a polyethylene terephthalate film has high crystallinity, a high melting point, exhibits heat resistance and chemical resistance, and has excellent mechanical properties such as strength and elastic modulus. It is known that this film has a property of absorbing ultraviolet rays, and particularly has a property of strongly absorbing ultraviolet rays of 320 nm or less. When this film is extended outdoors for a long period of time, its mechanical properties become remarkable. There is a disadvantage that it decreases. In order to improve the weather resistance of this film, a method of tightly bonding an ultraviolet absorber to the film surface as described in JP-B-46-24160 is known. According to this method, although the weather resistance is improved, it is difficult to firmly bond the ultraviolet absorber at a uniform concentration to the film surface, and the weather resistance sufficient to withstand long-term outdoor expansion and outdoor exposure is provided. It was difficult to do.

Therefore, a method of forming an acrylic resin film containing an ultraviolet absorber on one side of a polyethylene terephthalate film has been proposed (Japanese Utility Model Application Laid-Open No. 56-159).
239, Japanese Patent Publication No. 4-2101, etc.). However, even with such a film, when the wound film is stored for a long period of time, a peeling phenomenon occurs particularly on the surface of the film, and there is a problem in blocking resistance and weather resistance.
Further, there has been a demand for a coating having scratch resistance.

[0004]

Under such a background, the inventors of the present invention have excellent transparency and weather resistance both at the initial stage and after exposure, and for storage over time, for house coating and the like. The present inventors have conducted intensive studies to provide an agricultural polyethylene terephthalate film having scratch resistance without impairing these excellent film properties, and as a result, have completed the present invention.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a biaxially stretched polyethylene terephthalate film on one side with an acrylic resin and 1 to 40 parts by weight based on 100 parts by weight of the resin. Part of the polyethylene terephthalate film on which the acrylic resin film containing the ultraviolet absorber and the spherical fine particles is formed, the average particle diameter of the spherical fine particles is assumed to be formed excluding the spherical fine particles. Agriculture polyethylene terephthalate film characterized by being in the range of 0.05 times or more and 3 times or less.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. 1. Polyethylene terephthalate film In the present invention, polyethylene terephthalate means not only polyethylene terephthalate homopolymer, but also copolymerized polyethylene terephthalate or polyethylene terephthalate in which the repeating unit of ethylene terephthalate is 85% or more and the remainder is other components. 85% by weight or more and the remaining 15% by weight or less include a polymer blend which is another polymer. Other polymers that can be blended include polyamides, polyolefins, and other types of polyesters. In this polyethylene terephthalate, if necessary, a lubricant, a coloring agent usually added to polyethylene terephthalate,
Additives such as stabilizers and antioxidants can be added.

[0007] The polyethylene terephthalate film according to the present invention is stretched biaxially.
The width is preferably 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, and it is not preferable. If the stretching ratio exceeds 5.0 times, the strength of the product will be sufficient. Is not preferred. The stretching ratio is 2.5 to 4.0 in each of the biaxial directions.
A range of 2 times is particularly preferred. The method for producing the biaxially stretched film is not particularly limited, and may be any conventionally known method, for example, stretching sequentially or simultaneously biaxially in the vertical and horizontal directions.

The polyethylene terephthalate film according to the present invention preferably has a thickness of 0.01 to 0.3 mm. When the thickness is less than 0.01 mm, the strength of the product is not sufficient, which is not preferable.
If it exceeds m, the film becomes hard and difficult to handle, which is not preferable.

[0009] 2. Coating Film The agricultural polyethylene terephthalate film according to the present invention is formed on one surface thereof with a coating made of an acrylic resin containing an ultraviolet absorbent and spherical fine particles.

In the present invention, the acrylic resin is mainly composed of a methacrylic acid alkyl ester monomer or a methacrylic acid alkyl ester as a branch component in the presence of a crosslinked acrylate-based elastic material as a trunk component. And a graft copolymer obtained by polymerizing a mixture of a vinyl monomer and a copolymerizable vinyl monomer, and preferably contains 5 to 80% by weight of a crosslinked acrylate elastic body. A crosslinked acrylate monomer is a polymer obtained by polymerizing a crosslinkable monomer and an alkyl (meth) acrylate monomer, or a vinyl monomer copolymerizable therewith. is there.

The crosslinking monomer may be any one which is usually used as a polyfunctional compound. Specific examples thereof include ethylene glycol dimethacrylate, 1,3-
Butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, propylene glycol dimethacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane tetramethacrylate, dipropylene glycol dimethacrylate, divinylbenzene, divinyl adipate, diallyl phthalate, diallyl maleate, Allyl acrylate, allyl methacrylate, triallyl cyanurate and the like,
These may be used in combination of two or more.

The alkyl (meth) acrylate monomer is an alkyl ester of acrylic acid or methacrylic acid, and specifically, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, Isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid
n-propyl, isopropyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate,
Examples thereof include decyl methacrylate and the like. Generally, an alkyl acrylate having 1 to 20 carbon atoms in an alkyl group and / or an alkyl methacrylate having 1 to 20 carbon atoms in an alkyl group are used. You may mix and use.

Vinyl monomers copolymerizable with these (meth) acrylic acid alkyl ester monomers include methacrylic acid and alkyl esters of methacrylic acid (alkyl groups having 1 to 12 carbon atoms), and dialkyl of itaconic acid. Examples thereof include esters (having 1 to 10 carbon atoms in the alkyl group), acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, styrene, alkyl-substituted styrene, α-methylstyrene, and the like. These monomers are used in an amount of 40% by weight or less, preferably 25% by weight or less.

The crosslinked acrylic ester-based elastic material is preferably produced by an emulsion polymerization method. The polymerization initiator that can be used at this time is a usual free radical generation initiator. Specific examples include inorganic peroxides such as potassium persulfate and ammonium persulfate; organic hydroperoxides such as cumene hydroperoxide, p-menthane hydroperoxide and ditertiary butyl hydroperoxide; benzoyl peroxide, lauroyl peroxide Examples thereof include organic peroxides such as oxide and cumene peroxide, and azo-based initiators such as azobisisobutyronitrile.

Further, ordinary redox initiators obtained by combining these with reducing agents such as sodium sulfite, sodium acid sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, glucose, polyamine and hydroxyacetone ascorbate are also used. sell.
Examples of the emulsifier include ordinary surfactants for emulsion polymerization. For example, anionic surfactants such as sodium, potassium and ammonium salts of alkyl sulfates having 8 to 20 carbon atoms and sodium and potassium salts of aliphatic carboxylic acids such as lauric acid, stearic acid and palmitic acid, and alkylphenols And non-ionic surfactants such as aliphatic alcohols and reaction products of polypropylene oxides and ethylene oxide.
In some cases, two or more of these surfactants can be used in combination. Further, a surfactant such as a naphthalene formaldehyde condensed sulfonate may be added. If necessary, a cationic surfactant such as an alkylamine hydrochloride can be used.

As a method for producing a crosslinked acrylic ester-based elastic material, the following emulsion polymerization method can be mentioned. (1) A method in which a small amount of a crosslinkable monomer is added to an alkyl acrylate monomer or a mixture of an alkyl acrylate monomer and a vinyl monomer copolymerizable therewith to polymerize. (2) An alkyl acrylate monomer or a mixture of an alkyl acrylate monomer and a vinyl monomer copolymerizable therewith is further added to the polymer emulsion obtained by the method of (1). To polymerize. (3) The method of (2), wherein an alkyl acrylate monomer or a mixture of a vinyl monomer copolymerizable therewith is added and polymerized in the presence of a small amount of a crosslinking agent.

(4) An uncrosslinked polymer is produced by emulsion polymerization of an alkyl acrylate monomer or a mixture of an alkyl acrylate monomer and a vinyl monomer copolymerizable therewith. Next, in this polymerization system, further, in the presence of a small amount of a crosslinkable monomer, an alkyl acrylate monomer, or an alkyl acrylate monomer and a vinyl monomer copolymerizable therewith. A method of polymerizing by adding a mixture. (5) To one of the polymer emulsions obtained by the methods (1) to (4), an alkyl acrylate monomer or a vinyl monomer copolymerizable therewith is further added to form a crosslinkable monomer. A method of polymerizing without adding a body or adding a small amount.

The average particle diameter of the crosslinked elastomer emulsion particles is adjusted by adjusting the amount of the surfactant and the amount of the aqueous medium to be used. Preferably, it is in the range of 0.30 μm. If the thickness is less than 0.05 μm, the mechanical strength of the acrylic resin used as the coating film is reduced,
If it exceeds μm, stress whitening becomes remarkable, which is not preferable.
Further, the crosslinked acrylate-based elastic body preferably has a gel content of 80% or more and a swelling degree of 15 or less as measured by the following method.

The gel content and the degree of swelling were determined by taking a predetermined amount (W ₀ ) of the crosslinked elastic material, and adding it to methyl ethyl ketone at room temperature.
The swollen weight (W ₁ ) after immersion for 8 hours and the weight (W ₂ ) after drying the sample with a vacuum dryer were measured.
It can be calculated by the following equation.

[0020]

## EQU1 ## Gel content = (W ₂ −W ₀ ) × 100 (%) Swelling degree = (W ₁ −W ₂ ) / W ₀

The gel content and the degree of swelling are determined by adjusting the temperature and the type of the initiator, the type and amount of the initiator, and the amount of the monomer constituting the elastic body, in addition to the adjustment of the type and amount of the crosslinkable monomer described above. It is preferably adjusted as appropriate because it is affected by various polymerization conditions such as the method of adding the monomer and the presence or absence of a molecular weight regulator. When the gel content is less than 80%, the acrylic resin for forming a film obtained from the elastic body is completely dissolved in an organic solvent described later or excessively swells, and the elastic body particles are deformed. Not preferred. Regarding the degree of swelling, if it exceeds 15, stress whitening tends to occur, which is not preferable.

The alkyl methacrylate monomer as a branching component to be grafted onto the crosslinked acrylic ester-based elastic material may be selected from the above-mentioned ones used in the production of the elastic material, and may be copolymerized with this. The vinyl monomer may also be selected from those exemplified as being used in the production of the elastic body.

In this case, it is preferable to select the type and combination of monomers so that the glass transition temperature (Tg) of the polymer or copolymer obtained from the monomer component to be grafted is 50 ° C. or higher. . When the Tg is less than 50 ° C., the blocking resistance of the acrylic resin film containing the graft polymer is deteriorated (it is easy to block), which is not preferable.

The graft polymerization reaction is preferably performed by an emulsion polymerization method, but may be performed by a solution polymerization method. For example, when graft polymerization is carried out by an emulsion polymerization method, a monomer to be grafted is added to an emulsion of a crosslinked acrylate-based elastic material, and if necessary, an emulsifier, a polymerization initiator, a molecular weight regulator, water and the like are added. Thus, ordinary emulsion polymerization conditions can be selected and carried out. The ratio of the grafted monomer to the crosslinked elastic emulsion is usually 10 parts by weight or more and 30 parts by weight or more based on 100 parts by weight of the solid content of the polymer.

The graft polymerization reaction is preferably performed by an emulsion polymerization method, but may be performed by a solution polymerization method. For example, when graft polymerization is carried out by an emulsion polymerization method, a monomer to be grafted is added to an emulsion of a crosslinked acrylate-based elastic material, and if necessary, an emulsifier, a polymerization initiator, a molecular weight regulator, water and the like are added. Thus, ordinary emulsion polymerization conditions can be selected and carried out. The ratio of the grafted monomer to the crosslinked elastic emulsion is usually 10 parts by weight or more and 30 parts by weight or more based on 100 parts by weight of the solid content of the polymer.

In the acrylic resin, besides the graft polymer, for example, an alkyl methacrylate monomer or a vinyl monomer copolymerizable with an alkyl methacrylate monomer as a main component Or a free methacrylic resin formed during the production of a graft copolymer.

Further, the acrylic resin is compatible with the graft polymer, and is blended with a transparent hard thermoplastic resin having a Tg of 50 ° C. or higher, such as a polyester resin, to form an acrylic resin for forming a film. Can be used. When the ratio of the crosslinked elastic body contained in the acrylic resin is 5
It is good to be in the range of -80% by weight, preferably 10-50% by weight. When the proportion of the crosslinked elastic body is less than 5% by weight, the mechanical strength is poor, and when it exceeds 80% by weight,
The blocking resistance of a film having this as a coating is poor, which is not preferable.

Examples of the type of the ultraviolet absorber include conventionally known ultraviolet absorbers such as salicylic acid compounds, cyanoacrylate compounds, benzophenone compounds, and benzotriazole compounds. Among these, a benzophenone-based compound and / or a benzotriazole-based compound are preferable from the viewpoints of solubility in an acrylic resin and weather resistance when applied to a polyethylene terephthalate film and used for agricultural purposes.

Examples of the benzophenone compound include 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, and 2-hydroxy-4-methoxy-2'-carboxybenzophenone. , 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-
Hydroxy-4-benzoyloxybenzophenone,
2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfonebenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4' -Dimethoxybenzophenone, 2-hydroxy-5-chlorobenzophenone, bis- (2-methoxy-4-hydroxy-5-benzoylphenyl) methane and the like.

As the benzotriazole compound, 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'-
Hydroxy-3 ′, 5′-di-tert-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-tert-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 ', 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 and the like.

Further, the benzophenone-based compound and the benzotriazole-based compound may also be used as a monomer or polymer. The amount of the ultraviolet absorber blended in the acrylic resin is 1 to 40 parts by weight, particularly preferably 5 to 30 parts by weight, based on 100 parts by weight of the acrylic resin. 1
If the amount is less than 10 parts by weight, the object of the present invention can be achieved.

The spherical fine particles may be any of conventionally known spherical fine particles as long as they have low solubility in an organic solvent, such as inorganic compound spherical fine particles or organic compound fine particles. Specifically, the inorganic compound spherical fine particles include silica spherical fine particles, glass spherical fine particles, hydrotalcite spherical fine particles, talc spherical fine particles, ferrite spherical fine particles, bentonite spherical fine particles, kaolin spherical fine particles, calcium carbonate spherical fine particles, alumina spherical fine particles. Fine particles, titania spherical fine particles, zirconia spherical fine particles, titanium oxide spherical fine particles, zinc oxide spherical fine particles, iron oxide spherical fine particles, and the like. Examples of organic compound fine particles include crosslinked acrylic resin spherical fine particles, fluororesin spherical fine particles, and vinylidene fluoride. Resin spherical fine particles, benzoguanamine resin spherical fine particles, silicone resin spherical fine particles, nylon resin spherical fine particles, epoxy resin spherical fine particles, crosslinked polystyrene resin spherical fine particles, phenol resin spherical fine particles, melamine resin spherical fine particles, polyolefin resin Spherical microparticles, polyethylene resin spherical fine particles, rubber spherical fine particles and the like. Among them, when evaluated from the viewpoint of transparency when applied to a polyethylene terephthalate film and used for agricultural purposes, organic compound spherical fine particles whose spherical fine particles have a refractive index close to that of the polyethylene terephthalate film are evaluated. It is preferable to select. These may be used alone or in combination.

In the present invention, the thickness of the coating assumed to be formed excluding the spherical fine particles means that the coating resin composition excluding the spherical fine particles is applied on the same film surface, and the liquid dispersion medium is dried and evaporated. Refers to the thickness of the solid matter attached to the film after The average particle diameter of the spherical fine particles is 0.05 times or more and 3 times or less, preferably 0.1 times or more and 2 times or less with respect to the film thickness. If the average particle diameter is larger than the above range, the adhesion strength of the coating to the base film is reduced, and the coating may be easily peeled, which is not preferable.

The amount of the spherical fine particles to be used may be appropriately determined according to the thickness of the base film and the average particle size of the spherical fine particles.
0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic resin, particularly 0.01 to 5 parts by weight in the case of inorganic compound fine particles.
A range of parts by weight is preferred. If the amount is less than 0.01 part by weight, the object of the present invention may not be sufficiently achieved. If the amount is more than 10 parts by weight, the adhesion strength of the coating to the base film is reduced, and the transparency is low. Is undesirably reduced.

The actual thickness of the coating composed of these compositions is not preferable because the object of the present invention is not achieved if the thickness is too small, and the coating tends to peel off if the thickness is too large. 10 μm is preferred.

In order to form a film, first, biaxially stretched polyethylene terephthalate is produced. Then, on one side of the biaxially stretched polyethylene terephthalate film, ketones such as methyl ethyl ketone, benzene, toluene, aromatic hydrocarbons such as xylene,
An acrylic solvent and an ultraviolet absorber are dissolved in an organic solvent obtained by mixing one or more kinds of acetates such as methyl acetate and ethyl acetate, and a solution in which spherical fine particles are dispersed is applied. The acrylic resin film may be formed by volatilization by a method such as heating.

The coating method is a roll coating method,
Any known method such as dip coating, brush coating, spray coating, bar coating, knife coating, gravure coating, and reverse coating may be used. After the coating composition is applied to the surface of the film, and the liquid dispersion medium is dried and volatilized, the adhered amount of the solid is usually 0.01 to 10 g / m ² , preferably 0.1 to 10 g / m ² .
５5 g / m ² .

If the adhesion between the film surface and the coating film derived from the coating composition used in the present invention is not sufficient, the film surface may be subjected to a plasma treatment before the application of the antifogging agent composition, Alternatively, the surface of the film may be modified by a method such as a corona discharge treatment.

When the agricultural polyethylene terephthalate film of the present invention is stretched and used as an agricultural coating material, the sun is directly received on the side provided with the coating.
That is, it is used so as to be outside the house or the tunnel. Furthermore, depending on conditions such as the temperature and humidity in the house, fogging may occur on the inner surface of the house of the film. It is preferable to form a coating having such an inorganic hydrophilic coating and an organic hydrophilic coating.

In particular, a coating composed of an aqueous dispersion of a hydrophobic acrylic resin having a glass transition temperature of 35 to 80 ° C. and a composition mainly composed of an inorganic colloid sol is preferred. The amount of the inorganic colloid sol is preferably 0.5 to 4 in weight ratio to the hydrophobic acrylic resin. The coating composed of these compositions has a solid content of usually 0.0% after the liquid dispersion medium is dried and evaporated.
1 to 10 g / m ^2, preferably preferably in the range of 0.1-5 g / m ^2.

[0041]

The agricultural polyethylene terephthalate film according to the present invention contains an ultraviolet absorbent and spherical fine particles in an acrylic resin film, and therefore has excellent transparency and weather resistance both at the initial stage and after exposure. Since it has these properties and has blocking resistance and scratch resistance without impairing these excellent coating properties even after storage over time, the utility value as an agricultural polyethylene terephthalate film is extremely large.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments, but the present invention is not limited to the following examples unless it exceeds the gist. Examples 1 to 5 and Comparative Examples 1 to 5 (1) Base polyethylene terephthalate film Each of the base and the base was stretched 3.5 times and the density was 1.392.
g / cm ² and a thickness of 150 μm.

(2) Preparation of Acrylic Resin for Coating (2) -1) Preparation of Acrylic Resin Solution A Production of Crosslinked Acrylic Ester Elastic Body 300 parts by weight of deionized water (hereinafter referred to as "polymerized can") , Simply indicating "part" means "part by weight"), 0.3 part of potassium persulfate, 0.5 part of disodium phosphate dodecahydrate,
After charging 0.3 parts of sodium hydrogen phosphate dihydrate and sufficiently purging with nitrogen, the internal temperature was raised to 70 ° C. The internal temperature was maintained at this temperature, and styrene 19.8
, 69.3 parts of butyl acrylate, 0.9 parts of allyl methacrylate, and 2.5 parts of sodium dioctylsulfosuccinate (emulsifier) were continuously added over 2 hours. Immediately after the addition was completed, 1.0 part of t-butylperoxy-2-ethylhexanoate and 2.2 parts of styrene were used.
Parts, butyl acrylate 7.7 parts, allyl acrylate 0.
One part mixture was added. After 30 minutes from the end of the addition, the internal temperature was raised to 90 ° C.
The reaction was continued for an hour to obtain a crosslinked elastic emulsion. The average particle size of this crosslinked elastic body was 0.20 μm, the gel content was 97.1%, and the degree of swelling was 7.2.

Production of Graft Copolymer The crosslinked elastic emulsion 400 obtained above was placed in a polymerization vessel.
The mixture was charged and replaced with nitrogen while stirring, and then the internal temperature was raised to 80 ° C. While maintaining the internal temperature at this temperature, a solution prepared by dissolving 0.15 part of sodium formaldehyde sulfoxylate in 3.0 parts of deionized water was added with stirring, and then 30.0 parts of methyl methacrylate and n-octyl mercaptan were added. A mixture of 0.03 part and 0.15 part of paramenthane hydroperoxide (50% solution) was continuously added over 30 minutes. After completion of the addition, the polymerization reaction was continued for another 30 minutes to obtain a graft copolymer emulsion.
The glass transition temperature (Tg) of the copolymer itself obtained from the grafted monomer component was 108 ° C. The obtained graft copolymer emulsion was salted out according to a conventional method, and the polymer was separated by filtration, washed with water, and dried to obtain a graft copolymer powder.

Preparation of Resin Solution To 6.5 parts of the graft copolymer obtained above, methacrylic resin (methyl methacrylate / ethyl methacrylate
And 13.5 parts of beads).
This mixture is mixed with 64 parts of methyl ethyl ketone and 16 parts of toluene.
Into a mixed solvent consisting of
An acrylic resin solution A having a solid content of 20% by weight was prepared.

(2) -2) Preparation of Acrylic Resin Solution 1 Preparation of Crosslinked Acrylate Elastomer In a polymerization vessel, 250 parts of deionized water, 2.0 parts of sodium dioctylsulfosuccinate, 2.0 parts of sodium formaldehyde sulfoxy A rate of 0.05 part was charged and the atmosphere was sufficiently replaced with nitrogen.

While stirring the contents of the polymerization vessel, 1.6 parts of methyl methacrylate, 8.0 parts of butyl acrylate,
A mixture consisting of 0.4 part of 1,3-butylene methacrylate, 0.1 part of allyl methacrylate, and 0.04 part of cumene hydroperoxide was charged. 7 temperature inside the polymerization can
The temperature was raised to 0 ° 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 methacrylate, 0.25 part of allyl methacrylate and these monomers were added to the polymerization vessel. A mixture of cumene hydroperoxide in an amount of 0.05% by weight based on the mixture was added over 60 minutes. The obtained crosslinked elastic body had an average particle diameter of 0.12 μm, a gel content of 90%, and a swelling degree of 10.

2 Production of Graft Copolymer A solution prepared by dissolving 0.01 part of sodium formaldehyde sulfoxylate in 3.0 parts of ionic water was added to a polymerization vessel containing the crosslinked elastic emulsion of the above item 1. , 5.0 parts of methyl methacrylate, 5.0 parts of butyl acrylate, 0.1 part of allyl acrylate and 0.1 part of these monomers.
A mixture to which 03% by weight of cumene hydroperoxide was added was added continuously over a period of 30 minutes. After completion of the addition, the polymerization reaction was continued for another 30 minutes.

A solution prepared by dissolving 0.05 part of sodium formaldehyde sulfoxylate in 3.0 parts of ionic water was added to the polymerization vessel, and the temperature was raised to 80 ° C. to obtain 52.25 parts of methyl methacrylate. 2.75 parts of butyl acrylate, 0.1% of paramenthane hydroperoxide (50% solution).
A mixture of 13 parts was added over 30 minutes. After completion of the addition, the polymerization reaction was continued at 80 ° C. for 30 minutes to obtain a graft copolymer emulsion. In addition, the glass transition temperature (Tg) of the copolymer itself obtained from the monomer component grafted to the outermost layer was 103 ° C. The obtained graft copolymer emulsion is salted out according to a conventional method,
The polymer was separated by filtration, washed with water, and dried to obtain a powder of the graft copolymer.

3 Preparation of Resin Solution 20.0 parts of the graft copolymer obtained in the above 2 was placed in a mixed solvent consisting of 64.0 parts of methyl ethyl ketone and 16.0 parts of toluene and stirred, and the solid content was 20. An acrylic resin solution of 0% by weight was prepared.

(3) Formation of Coating Film An ultraviolet absorbent of the type shown in Table 1 and spherical fine particles (average particle size is μm) were added to the acrylic resin solution prepared according to the method described in (2) above. It was added at the ratio shown in the table (meaning the ratio to the solid content of the resin).
The solution after the addition was applied to one surface of a polyethylene terephthalate film by a gravure coating method, and the coated surface was heated to evaporate the solvent to form a coating containing an ultraviolet absorber.

(4) Evaluation of polyethylene terephthalate film Various properties of the polyethylene terephthalate film obtained in (3) were evaluated by the methods described below, and the results are shown in Table 2.

(4) -1) Properties of Film Before Outdoor Exposure Coating Strength of Coating A cellophane tape (Nichiban) was attached to each surface on which the coating of each film was formed, and after removing the cellophane tape, The state of peeling of each film was visually observed. The evaluation criteria are as follows. ：: Even if the cellophane tape was vigorously peeled off, the coating did not peel off at all and remained completely. Δ: When the cellophane tape is vigorously peeled off, a very small amount of the film is peeled off, but when the cellophane tape is slowly peeled off, the film is not peeled off and remains. X: A part or most of the coating film is peeled off even if the cellophane tape is slowly peeled off.

Transparency The transparency of the film was visually observed. The evaluation criteria are as follows. ：: transparency equivalent to that of the base polyethylene terephthalate film. Δ: Transparency was clearly observed. C: Transparency is extremely severe and does not stand for practical use.

Puncture Impact Strength A puncture impact tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.) was used to test a film sample having a length of 10 cm and a width of 10 cm, and the energy at break was expressed in kg · cm.

The scratch resistance of the coating The film is laid flat with the coating formed side up,
Changes in the coating when the iron ball weighing 50 g was dragged on the coating were visually observed. The evaluation criteria are as follows. ：: The coating film shows almost no trace of dragging an iron ball. X: A film in which traces of dragging an iron ball are clearly seen on the coating.

Blocking resistance Two pieces of film were superposed flat so that the surface on which the film was formed and the surface on which no film was formed were in contact with each other.
500 g / m ² in a gear oven temperature-controlled to
The test piece was taken out after applying the load of
The state of peeling of the film at the overlapped portion when the films were peeled was visually observed. The evaluation criteria are as follows. ：: Peelable with almost no resistance and no peeling of the film occurred. Δ: Some resistance to peeling, and slight peeling of the coating. ×: A film having remarkable resistance to peeling, and most of the film was peeled.

(4) -2) Properties of Film after Outdoor Exposure Each of the obtained polyethylene terephthalate films was exposed in a field in Shizuoka Prefecture from October 1994 to October 1996, and exposed. The puncture-impact strength and transparency were measured for the film afterwards. The evaluation criteria are the same as those for evaluating the properties of the film before outdoor exposure.

[0059]

[Table 1]

Notes in Table 1 * 1 The thickness of the solid matter adhered to the film after the coating resin composition excluding the spherical fine particles was applied to the film surface, and the liquid dispersion medium was dried and evaporated. * 2 Shown in parts by weight based on 100 parts by weight of acrylic resin. * 3 v: cross-linked polymethyl methacrylate particles w: spherical fluororesin fine particles x: spherical silicon resin fine particles y: spherical silica fine particles z: non-spherical silica fine particles * 4 X: 2- (2'-hydroxy-5) '-T-butylphenyl) benzotriazole Y: 2- (2'-hydroxy-3', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole Z: 2,4-dihydroxybenzophenone

[0061]

[Table 2]

Claims (6)

[Claims] 1. An acrylic resin comprising, on one side of a biaxially stretched polyethylene terephthalate film, an acrylic resin and 1 to 40 parts by weight of an ultraviolet absorbent and spherical fine particles based on 100 parts by weight of the resin. In the polyethylene terephthalate film on which the coating is formed, the average particle diameter of the spherical fine particles is in the range of 0.05 to 3 times the thickness of the coating assumed to be formed excluding the spherical fine particles. Characteristic polyethylene terephthalate film for agriculture. 2. The agricultural polyethylene terephthalate film according to claim 1, wherein the amount of the spherical fine particles is 0.01 to 10 parts by weight based on 100 parts by weight of the acrylic resin. 3. The agricultural polyethylene terephthalate film according to claim 1, wherein the spherical fine particles are an organic compound. 4. An acrylic resin comprising, as a main component, a methacrylic acid alkyl ester monomer or a methacrylic acid alkyl ester as a main component in the presence of a crosslinked acrylate-based elastic material as a trunk component. The agricultural polyethylene terephthalate film according to any one of claims 1 to 3, which is a graft copolymer obtained by polymerizing a mixture with a polymerizable vinyl monomer. 5. The agricultural polyethylene terephthalate film according to claim 1, wherein the acrylic resin contains a polyester resin. 6. The agricultural polyethylene terephthalate film according to claim 1, wherein an acrylic resin film is formed on one side, and the other side is provided with:
An agricultural polyethylene terephthalate film having a coating formed from an aqueous dispersion of a hydrophobic acrylic resin having a glass transition temperature in the range of 35 to 80 ° C and a composition containing an inorganic colloid sol.