JPH02112936A - Agricultural plastic sheet - Google Patents

Abstract

PURPOSE:To improve antiweatherability by forming the film of paint consisting mainly of fluorine containing copolymer having bridge parts, and acrylic polymer soluble with fluorine containing copolymer on a thermoplastic resin sheet. CONSTITUTION:Thermoplastic resin is given for example vinyl chloride resin, polyethylene resin, polyester resin or the like, particularly, soft vinyl chloride resin is generally used. And, solvent soluble fluorine containing copolymer of 10wt.% or more in fluorine containing rate based on the fluoro orefin unit is employed as fluorine containing copolymer having bridge parts. Acrylic polymer is acrylic acid or alcoholic ester of carbon number 1-12 of methacrylic acid, and acrylic copolymer of molecular weight 500-80000. The acrylic polymer employed herein is shown for example methylacrylate, methylmethacrylate or the like. The rate of main constitutional component is fluorine containing copolymer 30-90wt.% and acrylic polymer 10-70wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an agricultural plastic sheet.

[Prior Art] Many conventional agricultural plastic sheets have been coated with a protective coating material that has relatively good weather resistance, such as acrylic resin, in order to improve their weather resistance.

In addition, for the purpose of further improving weather resistance, a protective coating made of a fluororesin has been proposed (Japanese Patent Laid-Open No. 101043/1983).

[Problems to be Solved by the Invention] The plastic sheet described in JP-A-60-101043, which has been known as an agricultural plastic sheet with excellent weather resistance, has poor adhesion between the protective coat and the sheet. It was not durable enough for use.

The object of the present invention is to solve the above-mentioned problems of the prior art, that is, to provide an agricultural plastic sheet with excellent weather resistance and excellent adhesion of a protective coat.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes fluorine-containing copolymers (a) and (a) having a crosslinking site on a thermoplastic resin sheet. The purpose of the present invention is to provide an agricultural plastic sheet formed by forming a film of a paint containing as a main component an acrylic polymer (b) which is compatible with the acrylic polymer (b).

Examples of the thermoplastic resin used as the base material of the agricultural plastic sheet of the present invention include vinyl chloride resin, polyethylene resin, and polyester 1 fat. Among them, vinyl chloride resins, particularly soft vinyl chloride resins, are most commonly used. Such vinyl chloride resin includes, in addition to a homopolymer of vinyl chloride, 40% by weight of at least one monomer of vinyl chloride and vinyl acetate, ethylene, propylene, acrylic ester, meccrylic ester, etc.
Below, copolymers with preferably 30% by weight or less, and polymers compatible with these homopolymers or copolymers, such as ethylene-vinyl acetate copolymers, vinyl chloride-vinyl acetate A copolymer or the like may be blended. Furthermore, vinyl chloride resin is often blended with an appropriate amount of plasticizer and used as a soft vinyl chloride resin. The amount of plasticizer blended is vinyl chloride resin 100%
A range of about 30 to 70 parts by weight is preferably employed. Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, diisodecyl adipate, tricresyl phosphate, epoxidized soybean oil, and epoxidized linseed oil. Further, additives such as a lubricant, an antioxidant, an antistatic agent, a heat stabilizer, a coloring agent, and a flame retardant may be added to the vinyl chloride resin.

Furthermore, a surfactant may be added to the vinyl chloride resin for the purpose of antifogging. As such a surfactant, a nonionic surfactant is preferably employed.

In the present invention, the paint for forming a film on the thermoplastic resin sheet includes a fluorine-containing copolymer (a) having a crosslinking site and an acrylic polymer (b) that is compatible with (a).
The main component is used.

Here, as the fluorine-containing copolymer (a) having a crosslinking site, a solvent-soluble fluorine-containing copolymer having a fluorine content of 10% by weight or more based on fluoroolefin units is preferably employed.

The fluorine-containing copolymer (a) above has a fluorine content based on fluoroolefin units of 10% by weight or more, preferably 10 to 70% by weight, more preferably 15 to 50% by weight, and is in an uncured state. Those having an intrinsic viscosity of 0.01 to 4.0 dl/g as measured in tetrahydrofuran are used. Therefore, if the fluorine content is less than 10% by weight, the intended effect of improving weather resistance will be reduced. Further, when the intrinsic viscosity is within the above range, the coating properties as a paint will be good, and the physical properties of the formed film will also be excellent. As such a fluorine-containing polymer, a copolymer with an ethylenically unsaturated compound as a fluoroolefin and a comonomer copolymerizable with the fluoroolefin is preferably employed.

Examples of such fluoroolefins include tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene, and pentafluoropropylene. Among these, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, and hexafluoropropylene are particularly preferably employed. In addition, examples of ethylenically unsaturated compounds as monomers that can be copolymerized with fluoroolefins include olefins, vinyl ethers, vinyl esters, allyl ethers, allyl esters, acryloyl group-containing compounds, and methacryloyl group-containing compounds. Examples include compounds such as

Among these, olefins, vinyl ethers, vinyl esters, and allyl ethers have linear, branched, or alicyclic alkyl groups with about 1 to 10 carbon atoms, which have particularly excellent copolymerizability with fluoroolefins. Preferably.

In the fluorine-containing copolymer (a), it is preferable that the fluoroolefin-based (unit) content is 30 to 70 mol%, and if it is less than 30 mol%, the effect of improving weather resistance is insufficient (70 mol%). If the fluoroolefin and ethylenically unsaturated compound are used alone in the copolymer, the solubility in the solvent tends to decrease, which may cause problems in the coating process. Alternatively, two or more types may be used in combination.

Among the main components of the coating material of the present invention, the fluorine-containing copolymer (a) having a crosslinking site may be other components,
Curing agents or copolymers react with each other to form a three-dimensional network structure, giving favorable results such as improving the solvent resistance, acid resistance, and alkali resistance of the coating, so those having crosslinking sites are preferably employed. .

Examples of crosslinking sites include active hydrogen-containing groups such as hydroxyl groups, carboxylic acid groups, acid amide groups, amino groups, and mercapto groups, as well as active halogen groups such as epoxy groups, carbon-carbon unsaturated groups, and bromine and iodine groups. Examples include. Among these, active hydrogen-containing groups are preferred in that they have excellent reactivity with incyanate curing agents, aminoblast curing agents, etc. that are commonly used as curing agents, and hydroxyl groups are particularly preferred.

The method for introducing such a crosslinking site into the copolymer includes, for example, hydroxyalkyl vinyl ether, hydroxyalkyl aryl ether, hydroxyaryl vinyl ether,
Copolymerizing a monomer with a crosslinking reaction site such as hydroxyalkyl allyl ether, hydroxyalkyl vinyl ester, glycidyl vinyl ether, acrylic acid, methacrylic acid, aryl vinyl ether, diaminoethyl vinyl ether, or adding acid anhydride to a fluorine-containing copolymer. A method of reacting and adding a substance, isocyanate, alkyl (meth)acrylate, etc. is adopted. In addition, as a method of decomposing a part of the copolymer,
A method may also be employed in which a monomer having a hydrolyzable ester group is copolymerized and then the copolymer is hydrolyzed to generate carboxylic acid or hydroxyl groups in the copolymer. Furthermore, a method of introducing a carboxylic acid group by reacting a divalent carboxylic acid anhydride such as succinic acid with a hydroxyl group-containing copolymer is also adopted.

The acrylic polymer (b) that is compatible with the fluorine-containing copolymer (a), which is a main component of the paint of the present invention, is an alcohol ester of acrylic acid or methacrylic acid having 1 to 12 carbon atoms, It is an acrylic polymer with molecules N500~go, ooo. Such acrylic polymers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl methacrylate, 1so-butyl methacrylate, tert-
Examples include butyl methacrylate, n-butyl acrylate, tert-butyl acrylate, acrylonitrile, methacrylonitrile, and the like. Preferably, copolymers of two or more of these monomers, or copolymers of acrylic acid with alcohol esters other than those listed above, styrene, maleic acid, vinyl esters (vinyl acetate, etc.), vinyl silane, etc. coalescence is used. More preferably, in the acrylic polymer, the polymer having a crosslinking site is crosslinked by reaction with the crosslinking site of the fluorine-containing copolymer, so that the paint film has a three-dimensional network structure,
Shows excellent properties.

Here, the crosslinking site in the acrylic polymer (b) is preferably a hydroxyl group, a glycidyl group, an amide group, a silanol group, etc. For example, the introduction of a hydroxyl group is
2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxymethacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 3-hydroxy Butyl acrylate, 3-hydroxybutyl methacrylate,
4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, etc.Introduction of glycidyl group is possible with glycidyl acrylate, glycidyl methacrylate, (β
-Methyl)glycidyl acrylate, (β-methyl)glycidyl methacrylate, etc. Further, the introduction of an amide group is performed using acrylamide, methacrylamide, dimethylacrylamide, dimethylmethacrylamide, N -tert-
Butylacrylamide, N-tert-butylmethacrylamide, N-octylacrylamide, N-octylmethacturamide, diacetone acrylamide, diacetone acrylamide, etc. Silanol groups can be introduced using monomers such as vinylsilane and the above-mentioned acrylic polymers. Alternatively, it may be carried out by copolymerizing with a comonomer to form a copolymer.

Silanol groups can also be introduced by adding incyanate silane or a silane bubbling agent to a hydroxyl group-containing acrylic polymer.

Here, the acrylic polymer (b) may be a mixture of a polymer that loads a crosslinking site and a polymer that does not have a crosslinking site, and the polymer that does not have a crosslinking site is the above-mentioned polymer. It does not include copolymers with monomers having exemplified hydroxyl groups, glycidyl groups, amide groups, etc. The proportion of the acrylic polymer without crosslinking sites is preferably up to 50% by weight based on the acrylic polymer having crosslinking sites.

Furthermore, (a) and (b), which are the main constituent components of the paint,
Of course, it is possible to add a curing agent to (a)
A material that is compatible with the fluorine-containing copolymer (b) and the acrylic polymer (b) and hardens them is used. Examples of such curing agents include polyisocyanates, such as non-yellowing diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, and adducts thereof, and blocked isocyanates in which isocyanate groups are blocked with a blocking agent such as phenol. etc. can be suitably adopted. Furthermore, various curing agents such as melamine type, metal alkoxide type, urea resin type, polybasic acid type, epoxy type, and silanol type can also be used. Here, when the crosslinking site of the fluorine-containing copolymer (a) is a hydroxyl group,
Polyisocyanate-based and metal alkoxide-based materials are preferred. As the melamine curing agent, melamine partially etherified with one or more lower alcohols such as methanol, ethanol, propatool, and butanol is particularly suitable. Such a curing agent has an extremely useful effect on the formation of a tertiary network structure of a copolymer or polymer having crosslinking sites.

A catalyst may be used in combination with the curing agent for the purpose of accelerating curing (such curing aids include dibutyltin laurate for incyanate curing agents, and paratoluenesulfonic acid for melamine curing agents). The catalyst is used in an amount of 0.001 to 2 parts by weight per 100 parts by weight of the fluorine-containing copolymer.

The respective proportions of the main components in the paint of the present invention are (a) 30 to 90% by weight of the fluorine-containing copolymer; (b)
The content of the acrylic polymer is preferably 10 to 70% by weight. If the amount of the fluorine-containing copolymer is small, the fluorine content will decrease, and the desired effect of improving weather resistance will not be achieved, while if the amount of the acrylic polymer is too small, the adhesion to the substrate will decrease.

Therefore, each of the fluorine-containing copolymer and the acrylic polymer is not limited to one type within the above ratio range (of course, two or more types may be used in combination.Next, curing The agent is used in an amount of 0 to 20% by weight based on the total amount of the fluorine-containing copolymer and the acrylic polymer.

In addition to the main components, the paint contains 0.5 to 3% of an ultraviolet absorber based on the total amount of fluorine-containing copolymer and acrylic polymer, making it possible to further improve weather resistance. It is. Such ultraviolet absorbers include:
Conventionally known or well-known 2-hydroxybenzophenone,
2.4-hydroxybenzophenone, 2-hydroxide 4-n-octoxybenzophenone, 2-hydroxy-
4-(1-methyl-2-hydroxy)ethoxybenzophenone, 2-hydroxy-4-(2-hydroxy-3-
Benzophenones such as methacryloxy)propoxybenzophenone or 2-(2°-hydroxy-5°-
Benzotriazoles such as methylphenyl)benzotriazole and 2-(2°-hydroxy-3',5'-di-t-butylphenyl)benzotriazole are used alone or in combination.

Furthermore, an acrylic polymer (C) having a fluoroalkyl group may be added to such a paint to improve the water repellency of the plastic sheet. As the acrylic polymer (c) having such a fluoroalkyl group, the fluorine-containing copolymer (a) or the acrylic polymer (b)
It is preferable to use a material having a crosslinking site similar to that of the above, since water repellency and the like are maintained over a long period of time.

The amount of the acrylic polymer (c) having such a fluoroalkyl group is 0.000 parts per 100 parts by weight of the fluorine-containing copolymer (a) and the acrylic polymer (b).
It is preferable to use 1 to 30 parts by weight.

In addition, for the purpose of improving properties, paints include antifoaming agents, antistatic agents, pigments, dispersion stabilizers, viscosity modifiers, etc.
Additives such as leveling agents and anti-gelling agents can also be blended. The blending of pigments has the effect of hiding the film.

The coating material of the present invention has main components such as the fluorine-containing copolymer (a) and the acrylic polymer (b) as described above, and if necessary, a curing agent, an ultraviolet absorber, and an acrylic polymer having a fluoroalkyl group. (C) It can be obtained by dissolving other additives in an organic solvent. Examples of solvents that can be used include aromatic hydrocarbons such as toluene and xylene, alcohols such as propatool and butanol, ethyl acetate, and butyl acetate. esters such as methyl ethyl ketone, ketones such as methyl isobutyl ketone, glycol ethers such as ethyl cellosolve, and various commercially available dinals. The concentration of the coating components is preferably adjusted to 1 to 60% by weight, preferably 5 to 50% by weight in terms of workability in forming a film.

The preparation of the coating material is not particularly limited, and may be carried out using various equipment commonly used for coating coatings, such as a ball mill, paint shaker, sand mill, jet mill, three-roll mill, kneader, and the like. At this time, additives such as those exemplified above may be added.

In the present invention, the method of forming a paint film on a thermoplastic resin sheet is to apply the paint onto the molded body by brushing, spraying, flow coater, etc., or by dipping the sheet in the paint, The film is dried sufficiently to volatilize the solvent, and then heated or left at room temperature to form a film. The heat treatment at this time is carried out at a temperature below which the molded body does not deform, and for example, treatment at 60° C. for 10 minutes is sufficient.

A sufficient effect is observed when the thickness of the paint film formed is 2 to 100 μm. The thickness of the coating is determined by the concentration of the components of the coating material and the coating conditions, but there is no problem even if the coating is formed into a multilayer coating. The shape of the molded body is also not limited at all.

[Example] Examples 1 to 11. Comparative Examples 1 to 3 Paints Nos. 001 to 13 having the compositions shown in Table 1 were prepared. Paint No. 1~ on the surface of the soft vinyl chloride resin sheet
13, the film thickness of the film formed by the flow coater is 1
Adjust the thickness to 5μm, apply, and dry at room temperature.
A cured film was formed by heating at 0° C. for 10 minutes.

Table 2 shows the results of the following evaluation tests performed on the sheets on which the coatings were formed in this way.

Contact angle: The contact angle of water and n-hexadencane was measured.

Adhesion: The adhesion of the film was measured according to the method of ASTM-3359 at (1) initial stage, (2) after hot water immersion (60°C x 30 days), and (2) after 1000 hours of treatment with a sunshine weather meter, and evaluated by the number of remaining squares.

Weather resistance: Measured with a color measuring machine (manufactured by Suga Test Instruments Co., Ltd. = 5M-3) before and after processing for 1000 hours with a Sunshine Weather Meter, and the yellowing deterioration is determined as the difference (ΔY, I) before and after processing.

In Table 1, F-A of the fluorine-containing copolymer is TFE/HBVE/n-BVE=
It is copolymerized at a ratio of 48.1/12.5/39.4 (wt%), and the intrinsic viscosity (referred to as [η]) measured at 30°C in tetrahydrofuran is 0.15 (di/g). Copolymer. (The same applies hereinafter) FB is CTFE/HBVE/CHVE/EVE =
56.415.7/12.4/25. U, [η] =0
．． 21/di/g.

FC is HFP/HBVE/n-BVE=
66, 7/8.0/25.3° [η] = 0.08/
di/g.

FD is TFE/CHaCOOCH=CH2/C
Ht=CHCH20CHaCH20H=53.7/23
．． 1/23.2. [η] =0.18dl/g.

F-E is CTFE/EVE/HBVE/H.
t Ha9 = 39.4/17.2/9.5/33.9
．． [η co = 0.40 dl/g.

F-F is TFE /EVE /HBVE/(1:H2
=CHOCH,CF,CF2H=57.0/22.4/
10.8/9.8. [η] =0.10dl/g.

(TFE is tetrafluoroethylene, HBVE is ω-hydroxybutyl vinyl ether, n-BVE is n-butyl vinyl ether, CTFE is chlorotrifluoroethylene, CHVE is cyclohexyl vinyl ether, EV
E is ethyl vinyl ether, RFP is hexafluoropropylene, and Beoba 9 is a vinyl ether manufactured by Shell Chemical Co., Ltd. and having an alkyl group on a branch with 9 carbon atoms. ) M-1 is 1so-butyl methacrylate/n-butyl acrylate/2-hydroxyethyl methacrylate = 7
/2/1 (molar ratio) copolymer (
same as below).

M-2 is methyl acrylate/n-butyl acrylate/glycidyl acrylate = 8/1/1°M-3
represents n-butyl methacrylate/1so-butyl methacrylate/acrylonitrile/2-hydroxyethyl methacrylate = 1/7/1/1°M-4 represents methyl methacrylate/n-butyl methacrylate = 575°.

Fluoroalkyl group-containing acrylic polymer is CH2”CH
COOCHzGHz (CF2) l oF/1so-
Butyl methacrylate/n-butyl acrylate/2-
Hydroxythylmethacryd = 20/60/10/1
0% by weight copolymer.

The isocyanate curing agent is Coronate EH (manufactured by Nippon Polyurethane Co., Ltd.).

The ultraviolet absorber is Biosorb 130 (manufactured by Benma Yakuhin).

Comparative Example 2 is a soft vinyl chloride resin sheet on which a paint film is not formed.

Example 12 When Example 1 was carried out in the same manner as in Example 1 except that the drying conditions were changed to 120° C. for 1 minute, the same effects as in Example 1 were obtained.

[Effects of the Invention] The agricultural plastic sheet of the present invention is formed with a specific paint film that maintains good adhesion.
It has excellent weather resistance.

Claims (1)

[Scope of Claims] 1. A coating film of a paint on a thermoplastic resin sheet, the main component of which is a fluorine-containing copolymer (a) having a crosslinking site and an acrylic polymer (b) that is compatible with (a). Agricultural plastic sheet made of 2. The agricultural plastic sheet according to claim 1, wherein the paint further comprises (c) an acrylic polymer having a fluoroalkyl group. 3. The agricultural plastic sheet according to claim 1, wherein the acrylic polymer (b) has a crosslinking site. 4. The agricultural plastic sheet according to claim 1, wherein the paint further contains a curing agent.