JPS5998109A - Ultraviolet-absorbing film - Google Patents

Abstract

PURPOSE:To provide the titled film having excellent weather resistance and durability, and useful for agricultural use, etc., by compounding a crosslinking compound with a polymer obtained by the reaction of a specific benzophenone containing phenolic OH group and an acrylic acid ester containing glycidyl group, applying the mixture to a film and crosslinking the mixture. CONSTITUTION:A polymer having ultraviolet-absorbing capability is prepared by reacting a benzophenone derivative of formula I [R<1> is H or OH; R<2> and R<3> are H, OH or OCnH2n+1 (n is integer of <=18); at least one of R<1>-R<3> is OH] having two or more phenolic OH groups with a (meth)acrylic acid ester of formula II (m is 0 or 1) having glycidyl group, and polymerizing the obtained polymerizable ultraviolet absorber singly or together with a copolymerizable monomer. The polymer is mixed with a polyfunctional compound capable of forming a crosslinked structure with the polymer or forming a crosslinked structure by itself. The obtained mixture is laminated to the surface of a film or sheet, crosslinked, and subjected to the antifogging treatment to obtain the objective film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a laminated film with excellent weather resistance and ultraviolet absorption, in which a polymer having ultraviolet absorption ability is laminated on the surface of a film or sheet (hereinafter simply referred to as a film), and at least one side of the laminated film has excellent weather resistance and ultraviolet absorption. The present invention relates to a laminated film characterized by being subjected to drip-proof treatment. More specifically, the polymerizable ultraviolet absorber can be used alone or together with other copolymerizable supermers to form a cross-linked structure with a polymer obtained by emulsion (co)polymerization, or can be used alone. A lamination in which a mixture with a polyfunctional compound capable of forming a crosslinked structure is laminated on the surface of the film, and the surface layer blocks ultraviolet rays with wavelengths as short as 320 nm, and the durability of the surface layer is improved by crosslinking. The present invention relates to a laminated film particularly suitable for agricultural use, which prevents fogging and a decrease in light transmittance due to water condensation by subjecting at least one side of the film to drip-proof treatment.

Traditionally, thermoplastic resins such as polyethylene terephthalate, polycarbonate, and polypropylene have held an important industrial position as materials for fibers, films, and molded products due to their excellent tensile strength, chemical resistance, and heat resistance. There is. However, these thermoplastic resins are subject to significant deterioration due to ultraviolet rays emitted from the sun and fluorescent lights, reducing their excellent physical properties and, as a result, becoming unable to maintain the strength required for practical use. Are known. Therefore, when used outdoors, various ultraviolet absorbers have been developed and used to prevent deterioration due to ultraviolet rays. As for its usage, I)
A method of blending an ultraviolet absorber into a resin and melt-molding it;
Two methods are commonly used: II) coating the surface of the molded product with an ultraviolet absorber together with a suitable binder. However, in the method (2), the ultraviolet i absorber is distributed uniformly throughout the molded product or film.

In order to absorb harmful ultraviolet rays in the surface layer, it is necessary to use a large amount of ultraviolet absorber in total. Therefore, problems arise such as the miscibility of the ultraviolet absorber and the resin and the repeatability of the ultraviolet absorber due to heat during melt molding, and furthermore, the original physical properties of the resin may be impaired. I [
Method ) is more advantageous than method I) because it allows the ultraviolet absorber to be present in large quantities on the surface of the molded product or film, but the adhesiveness between the coating layer and the substrate and the relationship between the binder and the UV absorber There are various problems such as affinity. Currently known films with UV-cutting ability cannot meet these requirements in terms of long-term stability, hygiene, price, degree of coloring, etc., and each prefecture has its excellent characteristics. At present, we are eagerly awaiting the emergence of a UV-cutting film that has the same properties.

Based on this background, the inventors of the present invention have conducted intensive research and found that by laminating a composition with ultraviolet absorbing ability on the surface of a film, it is possible to maintain excellent weather resistance and ultraviolet absorbency for a long period of time. We have discovered a method to obtain a highly durable laminated film at low cost.

Specifically, in the present invention, first, ■ general formula: [where,
R1 is H or OH, R21R3 is H9OH or 0
CnH2+s (n is an integer of 18 or less) and b R
At least one of 1+ R2+ Rs is always OH. Polymerization obtained by reacting a benzophenone derivative having two or more phenolic hydroxyl groups represented by the following formula with a (meth)acrylic ester having a glycidyl group represented by the general formula: [where 1m is O or 1] A polymer having an ultraviolet absorbing ability obtained by polymerizing a UV absorber alone or with other copolymerizable polymers; A mixture with a polyfunctional compound that can form a crosslinked structure by itself is laminated on at least one side of the film, and then crosslinked to produce a laminated film. The laminated film thus obtained has a polymerizable ultraviolet absorber that is strongly bonded to the binder component through chemical bonding, and as a result can maintain long-term weather resistance and ultraviolet absorbency. Furthermore, since the binder component has a network structure made of a polyfunctional compound, it is highly durable and does not cause any change in appearance even after long-term use.

However, when the laminated film is used in an agricultural greenhouse, small water droplets are generated on the inner surface of the greenhouse, which prevents sunlight from passing into the greenhouse and inhibits the growth of agricultural crops. The present invention is a laminated film particularly suitable for agricultural use, which has been provided with long-term weather resistance by laminating a polymerizable ultraviolet absorber, and which has been treated with drip-proof treatment on at least one side to prevent fogging due to water condensation. is intended to provide.

As a drip-proof treatment method, it is possible to make one surface hydrophilic or one surface hydrophobic. Methods for making the surface hydrophilic or hydrophobic include (1) a method of kneading a hydrophilic agent or a hydrophobic agent into a base film and precipitating it on one surface; (■) a method of using a hydrophilic agent or a hydrophobic agent alone or with a binder; (2) A method of physically or chemically treating the surface of the base material. The drip-proof treatment in the present invention is not limited to any of these. However, the method of coating with a hydrophilic agent is the easiest to apply. As the hydrophilic agent, a nonionic surfactant is usually used. Examples include polyoxyethylene esters, polyoxyethylene ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene sorbitan esters, sorbitan esters, polyoxyethylene/polyoquine propylene copolymers, and the like.

Although drip-proofing effects can be obtained by applying these nonionic surfactants alone, durability is often poor due to poor adhesion to the base material.

The duration of drip resistance can be increased by using a suitable binder. As binders, acrylic acid or acrylic acid ester polymers, polyester yarn polymers, and polyurethane polymers are used.

Ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyamide polymer 1, etc. are used. By adding a crosslinkable polyfunctional compound to these binders, the drip-proof performance can be further maintained for a long period of time.

Substrates to be coated according to the present invention include:
Polyester, polycarbonate, polypropylene, nylon 6, nylon 66, polyimide, polyamideimide, polyesterimide.

Examples include sheets or films made of polyetherimide, polysulfone, etc.

When the adhesion of the ultraviolet absorbing coating layer and the drip-proof layer is low, it is preferable to subject the substrate to corona treatment, anchor coat treatment 1, or the like. The ultraviolet absorbing coating layer of the present invention exhibits sufficient adhesion even to polyethylene terephthalate film, which is said to have relatively poor adhesion, without being subjected to anchor coating treatment.

The case where a polyethylene terephthalate film is used as the base material will be explained in more detail. Polyethylene terephthalate film is most easily degraded by light around 320 nm. Therefore, it is necessary to block wavelengths of 320 nm or less as much as possible. On the other hand, if the laminate layer is provided so as to strongly absorb light with a wavelength longer than 360 nm, the layer will clearly be colored yellow, which is not preferable.

In consideration of the above-mentioned required absorption characteristics, in the present invention, the general formula: % formula % [where h Rlit, H or OH * R2+
R3 is H.

OH or 0CHH21+t (n is an integer of 18 or less), and at least one of R11R21R3 is always OH. ] By reacting a benzophenone derivative having two or more phenolic hydroxyl groups represented by the formula -m with a (meth)acrylic acid ester having a glycidyl group represented by the formula: [where 1m is 0 or 1] The obtained polymerizable ultraviolet absorber was used. When synthesizing this polymerizable ultraviolet absorber, if a special anionic compound is used as a catalyst, it is possible to obtain a target product that can be directly polymerized without complicated isolation or purification operations after the synthesis reaction is completed. The special anionic compound referred to herein is a benzophenone derivative in which hydrogen in at least one hydroxyl group is substituted with an alkaline earth element, and is easily obtained from the benzophenone derivative and an alkali metal hydroxide. By using this alkali metal salt as a catalyst, the synthesis yield is approximately 100%.
%, and furthermore, by simply neutralizing with concentrated hydrochloric acid after reflection and filtering off the precipitated alkali metal chloride, a chemical mixture containing no impurities other than the acrylic thread radically polymerizable compound can be obtained. Specific examples of alkali metals include lithium, sodium, potassium, and the like. In addition, the amount used is 2.5 to 25% of the benzophenone derivative.
mole%, preferably 5 to 12.5 mole%.

The polymerizable ultraviolet absorber obtained by the above synthesis method is a viscous oily compound and can be polymerized alone to form a coating layer with a homopolymer-containing cord liquid. In some cases, it may be more convenient to dilute with other (meth)acrylic acid esters before polymerization. At the same time, by combining various monomers used for dilution, the properties of the coat layer can be changed as desired. Specifically, ethyl acrylate,
Examples include methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, dimethylamino methacrylate, diethylamino methacrylate, glycidyl acrylate, glycidyl acrylate, 7-acrylic acid, and methacrylic acid.

The relative amounts of the benzophenone derivative (A), the glycidyl group-containing acrylic monomer (B), and the diluent (C) used in the present invention are determined by the ultraviolet absorption properties and how to use the finally obtained laminated film. Depending on the purpose, it can usually be changed within the range of the following formula: 0 0.10≦×≦0.75 More preferably.

0.25≦x≦0.75, and when X<0.10, the ultraviolet absorbing ability is insufficient, so it is not preferable to use it as an ultraviolet shielding filter. In addition, when X>0.75, the viscosity is too high, which tends to make handling such as emulsion polymerization difficult.

Specific examples of the benzophenone compounds represented by the above general formula used in the present invention include 2,4-dihydroxybenzophenone, 2,2'-dihydroxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone. , 2.2'4.4'-tetrahydroxybenzophenone, 2.2',4-trihydroxybenzophenone, and the like. Further, as the compound having a glycidyl group, glycidyl acrylate and glycidyl methacrylate are suitable.

The polymerization method of the above monomer is based on the emulsion polymerization method using ordinary water as a medium, and the concentration of the monomer is 10 to 40% by weight.
is preferred.

The ultraviolet absorbing emulsion composition thus obtained can be laminated to a film as it is or after being diluted appropriately with water. However, in order to improve the durability of the laminate, a polymer having ultraviolet absorbing ability can be used. A mixture is used with a polyfunctional compound that can be combined to form a crosslinked structure or can itself form a crosslinked structure.

Examples of polyfunctional compounds that can form a crosslinked structure by themselves and used in the present invention include formaldehyde thread-adducted metal products such as melamine, urea, and partial adducts of phenol and formalin; Products such as crosslinked emulsions obtained by emulsion polymerization of compounds having 1 or more (meth)acryloyl groups are used. In addition, examples of polyfunctional compounds that can form a crosslinked structure with a polymer having ultraviolet absorption ability include carboxylic acid or glycidyl group acrylic subpolymers or copolymers, and polyfunctional compounds that dissociate to form isocyanate groups upon heating during coating. Examples include phenolic addition compounds of isocyanates.

Further, the amount used is 5 to 50 wt-wt based on the solid content contained in the ultraviolet absorbing emulsion composition,
Preferably it is 15 to 40 wt-%.

If the amount used is less than 5 wt-1, sufficient durability cannot be imparted to the coating layer, and if more than 50 wt-1 is added, the coating thickness to provide a certain UV cut rate becomes too thick. This method is disadvantageous in that it is not only uneconomical but also reduces the adhesive strength between the coating layer and the base film. As a crosslinking method, there is a method of heating by heat treatment during coating or after coating. The thickness of the ultraviolet absorbing layer varies depending on its specific use, but is usually between 10 and 0.6 mm.
It is about μ.

On the other hand, as a drip-proof coating agent, an aqueous fractional liquid containing a water-insoluble polyester resin and a nonionic surfactant is excellent in durability of drip-proof performance and adhesion to polyethylene terephthalate film. The water-insoluble polyester resin referred to herein is one that contains a hydrophilic component consisting of a sulfonic acid alimetal base and/or a polyether group in its molecule, but does not contain a hydrophilic component to the extent that it becomes soluble in water. It is something. When a water-soluble polyester resin is used, a film with excellent initial drip-proof properties can be obtained, but its durability is poor.

It is also possible to improve the sustainability of the drip-proof performance by further incorporating a water-soluble resin from a specific company into the aqueous dispersion of the polyester resin and nonionic surfactant.

The present invention will be explained below with reference to some examples.

Examples 1 to 3 Preparation of ultraviolet absorbing emulsion Table 1 shows the composition of the acrylic monomer and ultraviolet absorbent used in emulsion polymerization. In both cases, an addition reaction between glycidyl methacrylate and the ultraviolet absorber was carried out using a monosodium salt of an ultraviolet absorber as a catalyst, and emulsion polymerization was carried out by L fc in a conventional manner without isolation or purification. All of the obtained emulsions were stable, and no abnormalities such as formation of precipitates occurred even after being left for several months.Coating based on polyester film After thoroughly mixing the following compositions, p with ammonia water
A coating liquid was prepared by adjusting HHO2 and increasing the viscosity. The base film used for coating was a biaxially oriented polyester film (125μ), which was coated on its corona-treated surface. For coating, use a 100 mesh gravure roll.

Approximately 6 μm of the coating was applied and dried at 140° C. for 1 minute and at 170° C. for 30 seconds to obtain a colorless and transparent laminated film (A). The thickness of the coating layer after drying by the drying method is 1.0 μm, and its light transmission characteristics are shown in FIG. Emulsion (Table-1, A1) 395
r SUMITEX M-391341 SUMITEX hardening agent ACX skewer 1 3v
Thickener (Blymar ASE-60”2)
12f water
1561 pieces liquid solid content (15 wt-% excluding cross-linking agent, 4.5 wt-% cross-linking agent) -
1 Noramine thread crosslinking agent manufactured by Sumitomo Chemical ■ 2 Acrylic emulsion manufactured by Rohm and Haas Co., Ltd. Light with a wavelength of approximately 100
You can see that it has been cut by %. Note that the film before coating is shown as Fi,2.

For comparison, a film having the following composition containing no crosslinking agent was similarly coated to obtain a colorless and transparent laminated film (B) with a coating thickness of 0.8 μm. This non-crosslinked type film also had exactly the same light transmission characteristics as shown in Figure 1.

Coating liquid composition (non-crosslinked type) Ultraviolet absorbing emulsion (Table-1, AI) 395
r Thickener (Gura 4 Mar AsE-60) 1
2f water
193f coat liquid solid content 15wt% Accelerated weathering test of coated film A weathering test of the laminated film according to the present invention. -U■ The test was carried out using an accelerated weathering tester (manufactured by Q-Panel Company, fluorescent ultraviolet light-condensing type). The results are shown in Table 2, and the weather resistance of both crosslinked type (A) and non-crosslinked type (B) is
Measurements of breaking strength, elongation, and viscosity before and after weathering tests revealed that the film was far superior to uncoated films.

Moreover, the coated surface of the non-crosslinked type (B) becomes white after about 500 hours of weathering test, whereas the crosslinked type (A) shows no change in appearance even after the same time test and remains colorless and transparent. there were.

Table 2 Accelerated Weather Resistance Test Results Example 1 exemplifies a method of applying a drip-proofing treatment to the polyester film coated with the ultraviolet absorber obtained in Examples 1 to 3 above.

Example 4 Terephthalic acid/isophthalic acid 1 was prepared by transesterification method.
5-Sodium sulfoisophthalate/ethylene glycol/neopentyl glycol = 54/43/3/451
A molar ratio of 55 polyesters was polymerized. A mixture of 200 parts of this polyester resin and 50 parts of n-butylseronrug was made into a homogeneous liquid at 150°C to 170°C, and this was added to 375 parts of water with vigorous stirring to obtain an aqueous dispersion. Add to this a nonionic surfactant (NOF E)
230) The polyester films obtained in Examples 1 to 3 were coated with the ultraviolet absorber using an aqueous solution containing 20 parts by weight of the nonionic activator per 100 parts by weight of the polyester resin.
The coating liquid was applied to the unfinished surface using an air knife coater. The coated mouse was 0.1 to 0.2 f/m. The drip-proof treated surface thus obtained had sufficient drip-proof properties and adhesion to the base polyester film, and this performance was maintained even after the drip-proof treated surface was treated with running water for 1 hour.

Comparative Example 1 Weatherproofing treated in the same manner as in Example 4, except that a nonionic surfactant (E230 manufactured by NOF Corporation) was added to 80 parts by weight per 100 parts by weight of the polyester resin. A polyester film was obtained. The defense thus obtained
Although the ta-treated surface has sufficient drip-proof properties, a portion of the coating layer is eluted when treated with running water. After being treated with running water for 1 hour, it lost its drip-proof performance.

Table 3 shows the performance of the drip-proof treated surfaces obtained in Example 1 and Comparative Example 1. The test method for each performance was as follows.

(1) Haze value: Measured using Hazemeter S (Toyo Seiki fM) in accordance with JIS K6714.

(2) Drip-proof property: After placing the lid on a container containing water with the drip-proof side facing inside, heat the container to 50℃,
The state of dew condensation on the processed surface was observed.

(3) Contact angle: goniometer type contact angle measuring device (
The contact angle with water was measured at 20° C. and 65SRH using an optical fiber (manufactured by Elma Optical Instruments Manufacturing Co., Ltd.).

(4) Adhesion: A 180'@M test was conducted using Cellotep A405 (manufactured by Chiban), and the remaining area of the anti-fv1 layer was expressed as a percentage.

(5) Water resistance: After washing the drip-proof treated surface with running water for 1 hour, the haze value, drip-proofness, contact angle, and adhesion were measured.

Translation -3 Akira 11!1 5rL length (rim) Procedural amendment (formality) 1 Display of incident 1981 Patent Application No. 207876 λ Name of invention UV absorbing film & person making corrections Relationship to the case Patent applicant 2-2-8 Dojimahama, Kita-ku, Osaka March 9, 1981 (shipment date March 29, 1981).

``Arc Brief explanation of drawings Figure 1 is a diagram showing the relationship between the light transmittance of a film and the wavelength of light.''

Claims (1)

[Claims] (1) ■General formula: [Here, R1 is H or oH% R21R3id
HIOH or 0CnH2njs (n is an integer equal to or less than 18), and at least one of Rlt R21R3 is always OH. ] A benzophenone derivative having two or more phenolic hydroxyl groups represented by the general formula: [where b
A polymerizable ultraviolet absorber obtained by a reaction with a (meth)acrylic acid ester having a glycidyl group represented by m1io or 1] is polymerized alone or copolymerized with other copolymerizable materials. A mixture of the obtained polymer having ultraviolet absorbing ability and a polyfunctional compound that can form a crosslinked structure with the polymer or that can form a crosslinked structure by itself is applied to at least one side of the film or sheet. 1. An external radiation absorbing film or sheet, characterized in that one or both sides of the laminated film or sheet obtained by laminating and then crosslinking are treated to be drip-proof.