JPS6054865B2 - polyester laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated film having excellent weather resistance and ultraviolet absorption, which is obtained by coating the surface of a polyester film with a composition having ultraviolet absorption ability.

More specifically, a composition obtained by emulsion (co)polymerizing a polymerizable ultraviolet absorber alone or together with other copolymerizable monomers is coated on the surface of a polyester film, and the surface area blocks ultraviolet rays with wavelengths shorter than 320n7TL. The present invention relates to a laminated film made as described above. Conventionally, polyethylene terephthalate and modified polyesters in which the acid component or glycol component is partially replaced with other components have been used industrially as materials for fibers, films, and molded products due to their excellent tensile strength, chemical resistance, and heat resistance. It occupies an important position.

However, these polyesters are severely degraded by ultraviolet rays emitted from the sun and fluorescent lights, especially rays with wavelengths shorter than 320 nm, reducing their excellent physical properties and making them impractical for practical use. It is known that the gate cannot maintain the required strength. Therefore, various ultraviolet absorbers have been developed and used to prevent deterioration caused by ultraviolet rays. As for how to use it, (
Two methods are commonly used: i) blending an ultraviolet absorber with a resin and melt-molding it, and (11) coating the surface of the molded product with an ultraviolet absorber together with a suitable binder. However, in method (i), the UV absorber is uniformly dispersed throughout the molded product or film, so in order for the surface layer to absorb harmful UV rays, a large amount of UV absorber must be used as a whole. need to be used. Therefore, problems arise such as the miscibility of the ultraviolet absorber and the resin and the escape ability of the ultraviolet absorber due to heat during melt molding, and furthermore, the original physical properties of the resin may be impaired. Method (11) is more advantageous than method (1) because it allows the ultraviolet absorber to be present in large amounts on the surface of the molded product or film, but method (11) is more advantageous than method (1) because it allows the ultraviolet absorber to be present in large amounts on the surface of the molded product or film. Since the solvent is applied and dried, it is necessary to recover the solvent, which is unhygienic and inevitably increases costs. In addition, there are various problems such as the adhesion between the coating layer and the base material and the affinity between the binder and the ultraviolet absorber. Therefore, a layer containing an ultraviolet absorber can be provided on the surface of a polyester film at low cost and in a sanitary manner, and furthermore, its ultraviolet absorption ability can be maintained without any change even after long-term use. If so, it would be of great industrial significance. In addition, a film laminated with layers having ultraviolet absorption ability in this way is
In addition to its excellent weather resistance, it is also suitable for various uses as an ultraviolet cut film.

For example, it can be used as a cover or packaging film to protect substances that are susceptible to discoloration, fading, or deterioration due to ultraviolet rays. Specifically, on the inside of window glass to prevent fading of furniture, curtains, etc. Applications include pasting applications, covering applications to prevent discoloration and fading of various products displayed in shop windows, and packaging applications, as well as packaging applications to protect items that are susceptible to photodegradation, such as drugs and oil and fat products, from deterioration. . There are many other uses for ultraviolet cut films in addition to those mentioned above, but considering how they are used, it is natural that they should be as colorless and transparent as possible, and at the same time have the property of almost completely blocking ultraviolet light. requested,
Hygiene, such as no precipitation of foreign matter from the film, is also important. However, currently known films with UV-cutting ability can meet these demands in terms of long-term stability, hygiene, price, degree of coloration, etc., and are widely used in various industries. At present, we are hoping for the emergence of a UV-cutting film with excellent properties.

Based on this background, the present inventors have arrived at the present invention as a result of intensive research.

That is, an object of the present invention is to produce a polyester laminated film that can maintain excellent weather resistance and ultraviolet absorption for a long period of time at a low cost by coating the surface of a polyester film with a composition having ultraviolet absorption ability. The goal is to obtain food in a healthy and hygienic manner.

More specifically, the general formula: [where R1 is H or 0H
and R2 and R3 are HlOH or 0cnH2+1(n
is an integer of 18 or less), and at least one of R1, R2, and R3 is always OH.

obtained by the reaction of a benzophenol derivative having two or more phenolic hydroxyl groups represented by the following formula with a (meth)acrylic acid ester having a glycidyl group represented by the general formula: [where m is O or 1] Excellent weather resistance and This is a method for producing a laminated film that has ultraviolet absorption ability. Due to the use of a polymerizable ultraviolet absorber, the laminated film obtained by the present invention has a strong chemical bond between the ultraviolet absorber and the binder component, and as a result, it can maintain weather resistance and ultraviolet absorbency over a long period of time. Furthermore, if an emulsion polymerization method using water as a medium is applied to the polymerization of ultraviolet absorbers, there will be no scattering of organic solvents or low-molecular weight compounds other than evaporation of water during coating, making it hygienic and safe. Has characteristics. the use of non-fugitive UV absorbers;
The fact that the coating layer does not contain volatile or diffusible organic solvents is the main reason why the laminated film of the present invention is hygienic, but at the same time, this property also makes it possible for the laminated film to be used in a wide range of applications. It shows. For example, depending on the application, if the laminated film of the present invention is to be further processed and used, it may be possible to apply a top coat, provide an adhesive layer or a vapor deposition layer, etc. In such cases, a coater or vapor deposition device may be used. A major advantage of the film according to the present invention is that there are no components that volatilize in the film, and there is no change in the concentration of the ultraviolet absorber. The laminated film of the present invention cuts at least 60% of UV rays with wavelengths shorter than 320 nTL due to the surface area containing the UV absorber, and does not transmit light with wavelengths that are most harmful to the polyester film that is the base film. Further, as a matter of course, the light rays passing through the laminated film of the present invention contain almost no ultraviolet rays.

The wavelength of the light beam to be cut and the cutting rate can be selected from a wide range depending on the type of ultraviolet absorber, the concentration in the coating layer, and the thickness of the coating layer, but 360n7Ti. If a coating layer is provided to strongly absorb light with a longer wavelength, it will be clearly colored yellow, which is inappropriate from the point of view of one of the purposes of the present invention, which is colorless and transparent. , since it does not cause deterioration to the polyester base film, it is not particularly important from the viewpoint of imparting weather resistance. In consideration of the above-mentioned required absorption characteristics, the present invention provides the general formula: [Here, R1 is H or 0H,
R2 and R3 are HlOH or 0c0H2n+1 (n is 18
(the following integers), and at least one of R1, R2, and R3
One is always 0H.

] A benzophenone derivative having two or more phenolic hydroxyl groups represented by the general formula: [where m is O or 1
using a polymerizable ultraviolet absorber obtained by reaction with a (meth)acrylic acid ester having a glycidyl group represented by
7. If a highly 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 completion of the synthesis reaction.

The special anionic compound referred to herein is a benzophenone derivative in which hydrogen in at least one hydroxyl group is replaced with an alkali metal, and can be easily obtained from the benzophenone derivative and an alkali metal hydroxide.
By using this alkali metal salt as a catalyst,
The synthesis yield is almost 100%, and by simply neutralizing with concentrated hydrochloric acid after the reaction and filtering out the precipitated alkali metal chloride, a monomer mixture containing no impurities other than the acrylic radically polymerizable compound can be obtained. . Specific examples of alkali metals include lithium, sodium, potassium, and the like. Further, the amount used is 2.5 to 25 m01e%, preferably 5 to 12 m01e% based on the benzophenone derivative.
．． It is 5m01e%. The polymerizable ultraviolet absorber obtained by the above synthesis method is a viscous oily compound, which is polymerized alone to obtain a composition having ultraviolet absorbing ability, and this composition is coated to form a coating layer. I can do it.

In some cases, it may be more convenient to dilute and polymerize with another copolymerizable monomer, such as (meth)acrylic acid ester, to obtain a composition having ultraviolet absorbing ability. 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, methyl methacrylate,
Examples include n-butyl acrylate, hydroxyethyl methacrylate, dimethylamino methacrylate, diethylamino methacrylate, acrylic acid, methacrylic acid, and the like. Benzophenone derivative (4) used in the present invention, glycidyl group-containing acrylic monomer (B)
, and the relative amounts of the diluent monomer (C) can be generally varied within the range of the following formula depending on the ultraviolet absorption properties and the usage and purpose of the finally obtained laminated film.

More preferably: Therefore, 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. Moreover, the weight part of (4) 1 (B) is preferably 1.2 to 1.7, but is not limited thereto. Specific examples of the benzophenone compound represented by the above general formula used in the present invention include 2,4-dihydroxypenzophenone, 2●Z-dihydroxypenzophenone, 2●2'-dihydroxy-4
・4″-dimethoxypenzophenone, 2●2″・4・4
″-tetrahydroxybenzophenone, 2・2″●4-
Examples include trihydroxybenzophenone. Further, as the compound having a glycidyl group, glycidyl acrylate and glycidyl methacrylate are suitable. The polymerization method for the above monomers is based on a conventional emulsion polymerization method using water as a medium, and the concentration of the monomers is preferably 10 to 40% by weight.

The ultraviolet absorbing emulsion composition thus obtained can be coated on a polyester film as it is or after being diluted appropriately with water, and has good adhesion to the polyester film as a base material.

If it is necessary to further increase the adhesion strength of the coating layer to the base material, a simple corona treatment is sufficient, but a special anchor coat may also be applied. The coating method is preferably the commonly used gravure coating or reverse coating method, and the thickness of the coating layer is generally 0.2 to 5μ (solid content) from a practical and economical perspective, but it can be used as desired depending on the application. Just change it to ゞ. By performing the coating treatment, the properties of the base film are not impaired at all, and on the contrary, if necessary, it is possible to simultaneously impart properties such as slipperiness and printability. As described above, in the present invention, the synthesis of the polymerizable ultraviolet absorber and the subsequent emulsion polymerization process do not necessarily require post-processing steps such as isolation and purification of monomers and polymers, and the coating There is no need for any special pre-treatment,
In addition, the coating uses water as a medium.For these reasons, the laminated film according to the present invention is inexpensive.

Furthermore, it goes without saying that this emulsion can be used as a coating treatment agent for other forms than films, such as fibers, sheets, molded products, and textiles, and can provide the same functions as films. There is no such thing.

The present invention will be explained below with reference to 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.

Both use monosodium salt of ultraviolet absorber as a catalyst,
An addition reaction between chrycidyl methacrylate and an ultraviolet absorber was carried out, and emulsion polymerization was carried out according to a conventional method 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. After thoroughly mixing the composition shown below, the pH was adjusted to 9 with aqueous ammonia and the viscosity was increased to prepare a coating liquid (4).

The base film used for coating was a biaxially oriented polyester film (25μ), which was coated on its corona-treated side. For coating, use a 100 mesh gravure roll, apply approximately 6μ and heat at 140℃ for 1 minute at 17
It was dried at 0° C. to obtain a colorless and transparent laminated film. The thickness of the coating layer after drying by the gravimetric method was 0.8μ, and its light transmission characteristics were shown in FIG. It can be seen that almost 100% of the light with the following wavelengths is blocked. Note that the film before coating is indicated by 2. Coating liquid composition IIl @ human μm! 1nonoJ
−−・−*Accelerated weathering test of acrylic emulsion coated film manufactured by Rohm and Haas The weathering test of the laminated film according to the present invention was conducted using the Q-W accelerated weathering tester (manufactured by Q-Panel Company, fluorescent ultraviolet light condensation type). It was done using

The breaking strength, breaking elongation, and viscosity retention before and after the weathering test are shown in Figures 2, 3, and 4. From these figures, it can be seen that the laminated film 1 after coating is different from the uncoated film 2.
It was found that it has much better weather resistance. Example 4 Preparation and coating of mixture with other polyester resins A mixture was prepared by adding an aqueous polyester dispersion to the ultraviolet absorbing emulsion having the composition of Example 1, and coating was performed.

Polyester aqueous dispersion is terephthalic acid (49) / isophthalic acid (49) / 5-sodium sulfoisophthalic acid (2) / neopentyl glycol (60) / ethylene glycol (40) (all numbers in parentheses are mole %)
The polyester resin consisting of the polyester resin 30
A sample prepared by dispersing in water a sample modified with n-butyl cellosolve in an amount of 14 parts per saliva volume was used. The composition of the mixture (coating liquid (B)) of this aqueous polyester dispersion and the emulsion according to the present invention is as follows, and the coating conditions are the same as in Example 1. The laminated film after coating is colorless and transparent.
Its light transmission properties were the same as those shown in FIG. 1, and it also had excellent weather resistance. Coating liquid (B) composition comparison example In order to confirm the long-term stability of ultraviolet absorption ability, which is one of the characteristics of the present invention, No. 1 in Table 1 was used. The composition is the same as that of 1, but without performing the addition reaction between glycidyl methacrylate and 2,4-dihydroxypenzophenone, a mixture of (meth)acrylic acid ester monomers and a UV absorber simply dissolved by heating is used. Then, emulsion polymerization and coating were carried out in the same manner as in the examples.

The obtained film was colorless and transparent, but the coating liquid had extremely poor storage stability, and a large amount of ultraviolet absorber precipitated when left for half a day. Further, although the initial ultraviolet absorbing ability was the same as that shown in Fig. 1, the ultraviolet absorber escaped due to heat treatment as shown in the table below. On the other hand, the laminated film of the example showed no escape of the ultraviolet absorber even though it was subjected to the same heat treatment, and was very stable.

[Brief explanation of drawings]

FIG. 1 is a graph showing the light transmission characteristics of the polyester laminate film of the present invention.

Claims (1)

[Claims] 1. General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼ [Here, R_1 is H or OH, R_2, R_3
is H, OH, or OCnH_2_n_+_1 (n is an integer of 18 or less), and at least one of R_1, R_2, and R_3 is always OH. ] A benzophenone derivative having two or more phenolic hydroxyl groups represented by the general formula: ▲ Numerical formula, chemical formula, table, etc. ▼ [Here, m is 0 or 1] ) A polymeric composition having ultraviolet absorbing ability obtained by polymerizing a polymerizable ultraviolet absorber obtained by reaction with an acrylic ester alone or copolymerizing with other copolymerizable monomers is applied to at least one side of a polyester film. A polyester laminated film that has been coated to provide long-term weather resistance and UV protection. 2. The laminated film according to claim 1, wherein the polymer composition is an aqueous emulsion. 3. The polymer composition is an ultraviolet absorbing polymer in which the above polymerizable ultraviolet absorber is used alone or copolymerized with other polymerizable monomers, or the ultraviolet absorbing polymer and an acrylic polymer are used together. The laminated film according to claim 1 or 2, which is a mixture with a polyester polymer or a polyester polymer.