JPS62263045A - Ultraviolet screening laminated film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (b) Industrial application field This invention relates to a UV-blocking laminated film.

More specifically, the present invention relates to a transparent ultraviolet-blocking laminated film suitable for food protection, clothing protection, poster packaging, etc.

(B) Conventional Technology In general, foods are affected by oxygen, water vapor, light, ultraviolet rays, etc., causing moisture absorption, dehumidification, oxidation of fats and oils, discoloration, spoilage, etc. In this regard, gas-barrier (hereinafter abbreviated as barrier) films have been used as packaging materials for preserving foods, with the purpose of blocking gases such as oxygen and carbon dioxide, and water vapor.

As such barrier films, vinylidene chloride resin (hereinafter abbreviated as PVDC) films, vinyl alcohol resin films, saponified ethylene vinyl acetate copolymer films, polyamide films, acrylonitrile resin films, etc. are known. However, among these, PVDC films having high barrier properties are widely used.

These barrier films alone have mechanical strength,
Because it has insufficient heat sealability, moisture resistance, water resistance, heat resistance, etc., it is used by laminating it with other plastic films for reinforcement.

In addition, in order to block ultraviolet rays, dark printing or aluminum vapor deposition is performed on the above-mentioned barrier film, or lamination in which a UV absorber is added to the adhesive used when laminating the barrier film and other plastic films by dry lamination, etc. Films and the like are known.

(c) Problems to be Solved by the Invention However, if the UV rays are blocked by thick printing, etc., it is possible to block the UV rays from being irradiated to the packaged item, but it also blocks visible light, so the packaged item is One major drawback is that you can't see things.

In addition, when aluminum is deposited directly on the PVDC surface, or when an aluminum-deposited plastic film such as an aluminum-deposited unstretched polypropylene film is laminated, the packaged item cannot be seen as in the case of printing, and furthermore, due to the influence of the PVDC, the aluminum-deposited surface There are problems such as aluminum omissions such as pinholes, which deteriorate the barrier properties and further impair the appearance.

On the other hand, with the method of adding a UV absorber to an adhesive, if an effective amount of UV absorber is added, the adhesive properties of the adhesive will decrease, and if the amount added does not impair the adhesive property, it will not be enough to block UV rays. Not enough.

Furthermore, even if ultraviolet rays are blocked in any of the above cases, there is a problem that PVDC itself may change color or deteriorate its barrier properties due to long-term irradiation with ultraviolet rays. When PVD CM is used as the outermost layer of the film, the PVDC is irradiated with light before the adhesive layer, so it is difficult to prevent the above-mentioned deterioration.

(d) Means for solving the problem This invention was made in view of the above situation, and in particular, it provides conventional barrier properties, transparency, etc., and effectively blocks ultraviolet rays to the packaged items. As a result of intensive research in search of a moisturizing, ultraviolet-blocking laminated film, we decided to use PV instead of an adhesive layer.
It was discovered that by adding an ultraviolet absorber to the DC layer itself, ultraviolet rays can be effectively blocked and, surprisingly, the above-mentioned deterioration of PVDC caused by ultraviolet rays can be significantly prevented, leading to the completion of this invention.

As far as the inventors are aware, no UV-blocking film or UV-blocking laminated film in which a UV absorber is directly contained in a barrier film, particularly a PVDC film, is known.

Thus, according to the present invention, there is provided a UV-blocking laminated film characterized in that a vinylidene chloride resin layer to which an effective amount of a UV absorber is added is provided on at least one side of a transparent plastic film.

The plastic film used in this invention is a homopolymer of polyolefins such as polypropylene, polyethylene, and polybutene-1, polyesters such as polyethylene terephthalate, and polyamides such as nylon and polyxylene adipate, or a copolymer mainly composed of these. There are combinations, etc., and any of an unstretched film, a -axially stretched film, and a biaxially stretched film may be used.

The above-mentioned film may be used as a single film or as a layered film depending on the purpose, and in either case, transparency is required. Transparency in this invention means that the inside of the film cannot be seen from the outside with the human eye. It refers to something that can be seen through, so it also includes something that is semi-transparent. Specifically, it refers to something that has a visible light transmittance of about 10% or more.

Further, the thickness of the plastic film used in the present invention is appropriately selected depending on the intended use, but approximately 4 to 200 μm is suitable, and for example, 20 to 100 μm is preferable for a laminated film for food packaging.

The vinylidene chloride resin used in this invention refers to a vinylidene chloride homopolymer and a copolymer of vinylidene chloride. Copolymers of vinylidene chloride include vinylidene chloride, vinyl chloride, acrylic ester, methacrylic ester, Alternatively, copolymers with components such as acrylonitrile, and copolymers of these copolymer components with unsaturated monocarboxylic acids and unsaturated dicarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid as a third component, etc. Can be mentioned.

The above PVDCt in this invention! The thickness is generally 0.
5-10.0 μm is suitable, and 1.0-5.0 gm is preferred.

The laminated film of the present invention may have an anchor coat layer interposed between the transparent plastic film and the PVDC layer, if necessary. In this case, the plastic film is subjected to surface treatment and anchor coating treatment. For this surface treatment, common treatment methods such as flame treatment and corona discharge treatment are used.

The anchor coating agent is not particularly limited as long as it provides sufficient adhesion between the selected plastic film and the PVDC layer, and any agent known in the art can be used. Examples include anchor coating agents.

Examples of the ultraviolet absorbent used in this invention include, but are not limited to, benzophenone, benzotriazole, benzoate, salicylate, oxalic acid anilide, hindered amine, and the like.

In this invention, the PVDCJB is formed by coating or laminating films. In the case of coating, it may be a solvent coat or an emulsion coat, but
As described below, solvent coating is preferred in order to uniformly distribute the upper f2 ultraviolet absorber in the layer.

The ultraviolet absorber PVDCJ! The effective addition rate to
A suitable amount is 0.1 to 20% by weight based on the solid content of the pVDC; if the addition rate is small, the ultraviolet absorption rate will be low, which is undesirable, and if it exceeds the above range, the surface properties and appearance of the film will deteriorate and the barrier will deteriorate. This is not preferable because it reduces performance.

The method for incorporating the ultraviolet absorber into PVDC5 is such that the absorber is uniformly distributed in pVDclfJ,
A preferred method is to prepare a solvent PVDC uniformly dissolved or dispersed in a solvent that is compatible with C and the above-mentioned absorbent, coat this on the plastic film, and then dry it to form a PVDC calendar. In this case, the solvent is toluene,
Examples include methyl ethyl ketone and tetrahydrofuran.

In addition, in the preparation liquid of the above-mentioned solvent PVDC, silica, which is known in the art in terms of mechanical suitability such as avoiding adhesion between the film and roller or between films during film forming, is added.
Wax etc. may be added as appropriate.

The ultraviolet-blocking laminated film of the present invention obtained as described above does not contain an ultraviolet absorber in the adhesive layer as in the past, but is made of a barrier film, especially PVDCF.
Since it is directly contained in J, it contains more of the absorbent than before and effectively blocks ultraviolet rays.

Furthermore, since PvDCPi itself directly contains an ultraviolet absorber, the PVDC layer will not be degraded by light even if light is irradiated from either the front or back of this laminated film.

When using the ultraviolet-blocking laminated film of the present invention for packaging foods, etc., when using it by directly vapor-depositing aluminum on a PVDC calendar or bonding it with aluminum-deposited plastic to enhance the barrier properties, the laminated film of the present invention is Pinholes (aluminum holes), etc. that occur in aluminum vapor-deposited films, etc., which cannot be avoided by any means, do not occur.

Generally, the laminated film used for the above packaging is made by applying aluminum vapor deposition, printing, etc. as described above so that the inner surfaces can be bonded together and formed into a bag shape, and then an adhesive film is added to this surface for protection. However, by using the laminated film of the present invention, it is possible to provide a bag with higher barrier properties with a simpler layer structure than conventional ones.

(E) Examples The present invention will be explained in detail with reference to Examples below, but the invention is not limited thereby.

In addition, the measurement method of each physical property in Examples and Comparative Examples is based on the following method.

(1) Oxygen permeability (cc/m'/24hr) manufactured by Modern Control Co., Ltd.
Mocon-OX
Dry oxygen was used at 20° C. using a TRAN-100 model.

(2) Color difference Measured with a color difference meter SZ-Σ80 manufactured by NEC Corporation. The larger the number, the more discolored it is.

(3) Aluminum vapor deposition was performed on the pinhole PVDC surface, ultraviolet rays were irradiated from the plastic film side serving as the base material, and the aluminum vapor deposited surface was visually observed and judged as follows.

・Almost no pinholes・・・・・・・・・Excellent・
There are many pinholes ・・・・・・・・・・・・Possible・There are many pinholes ・・・・・・・・・・・・Not possible (4
) Lamination Strength The contact force between the unstretched polypropylene film of the strip-shaped laminate cut into a width of 15 ms and PVDC5 is expressed as the tension (g/151 am) measured using a tensile tester manufactured by Toyo Baldwin Co., Ltd. using the T-peel method.

In addition, in (1), (2), and (3), ultraviolet rays were irradiated for 30 hours using a standard Uv long life fade tester manufactured by Suga Test Instruments. For (1) and (2), the oxygen permeability and color difference before and after irradiation with ultraviolet rays were measured.

In an example, an axially stretched polypropylene film (thickness 20 μm) was treated with corona discharge to a surface with a contact angle of 3° to water.
A condensate of toluene diisocyanate and hexanetriol (Koro-L, manufactured by Nippon Polyurethane Co., Ltd.) was applied using a gravure coater at a concentration of 0.2 g/Il'' and dried at 110°C for 10 seconds.

The coated surface was coated with the following formulation solution using a reverse coater at a coating solution temperature of 50° C. so that the solid matter upon drying was 3 g/l*', and dried at 110° C. for 30 seconds.

The oxygen permeability, color difference and pinholes of the coated film thus obtained were measured. The results are shown in Table 1.

On the other hand, unstretched polypropylene film (thickness 40μ
Polyurethane adhesive (Japan Ink Group, E
PS-75-A, KW-40), the solid content when drying is 3
g/+" and dried.

Then, the PVDC-coated surface and the adhesive-coated surface were dry-laminated by a conventional method, and after aging at 40° C. for 2 days, the lamination strength of the obtained stonework film was measured. The results are shown in Table 1.

[Prescription liquid]

Solid content weight ratio/vinylidene chloride copolymer [manufactured by Asahi Kasei Corporation; P2O4] ・・・・・・10
0 parts by weight/wax (melting point 78°C) ・・・・・・
1 part Ji 1 part, silica-based fine powder (particle size 3μ)...
...0.1 part by weight Ultraviolet absorber (benzotriazole type) [Manufactured by Sumitomo Chemical Co., Ltd.: Sumisorb 3GO (Sumisorb 300)
) ・・・・・・ 1 part by weight・Methyl ethyl ketone ・・・・200 parts by weight・
Tetrahydrofuran...300M parts/Toluene...100i1
[Reduction part/dissolution temperature...60
Example 2-5 The same procedure as in Example 1 was carried out except that the addition rate of the ultraviolet absorber used was changed as shown in Table 1, and the results shown in Table 1 were obtained.

Example 6 A biaxially oriented polyethylene terephthalate film (thickness 116 mm) was used as a plastic film used as a base material.
The same procedure as in Example 1 was carried out except that the addition rate of the ultraviolet absorber used was changed to 5 parts by weight. Table 1 shows the results.
Shown below.

Example 7 The same procedure as in Example 1 was carried out, except that a two-wheel stretched polyethylene terephthalate film (thickness: 1168 m) was used as the base plastic film, and the addition rate of the ultraviolet absorber was changed to 10 parts by weight. The results are shown in Table 1.

Example 8 Biaxially stretched nylon film (thickness 215 μm) as a base material
) and the addition rate of the ultraviolet absorber was changed to 5M and 11 parts. Table 1 shows the results.
Shown below.

Example 9 A benzophenone type (manufactured by Sumitomo Chemical Co., Ltd.: Sumisorb 130) was used instead of a benzotriazole type ultraviolet absorber.
The same procedure as in Example 1 was carried out except that the addition rate was changed to 5 parts by weight. The results are shown in Table 1.

Comparative Example 1 The same procedure as in Example 1 was carried out except that no ultraviolet absorber was added. The results are shown in Table 1.

Comparative Example 2 No ultraviolet absorber was added to the PVDC layer, but 5 parts of a benzotriazole ultraviolet absorber (manufactured by Sumitomo Chemical Co., Ltd.; Sumisolve 300) was added to the adhesive based on the solid content of PVDC. The same procedure as in Example 1 was carried out except for this. The results are shown in Table 1.

(The following is a blank space) As is clear from the above results, by adding an effective amount of an ultraviolet absorber to PvDCJll, it was possible to suppress changes in PVDC such as a decrease in barrier properties and discoloration due to light and ultraviolet rays.

(F) Effects of the Invention According to the present invention, a laminated film that contains a larger amount of ultraviolet absorber than conventional ones, effectively blocks ultraviolet rays from being packaged, and is translucent can be obtained. It is ideal as a packaging material for preserving foods, etc. Furthermore, since the barrier film, particularly the PVDC layer, directly contains an ultraviolet absorber, deterioration of the PVDC layer due to ultraviolet rays can be prevented even if either the front or back of the film is turned outward during packaging. Sa°
Furthermore, even if an aluminum vapor deposited film or the like is formed on the PVDC layer and irradiated with light, pinholes etc. in the aluminum vapor deposited film will not occur.
A revolutionary packaging film with higher barrier properties can be obtained. Furthermore, when the laminated film of the present invention is used by adhering it to the surface of a poster, etc., it is possible to prevent the poster, etc. from discoloring due to light, and it can be provided as a novel protective film for use in this field.

Claims (1)

[Claims] 1. On at least one side of the transparent plastic film,
An ultraviolet-blocking laminated film characterized by having a vinylidene chloride resin layer added with an effective amount of an ultraviolet absorber.