JP2002120330A - White light-resistant laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white light-resistant laminated film in which discoloration and deterioration by ultraviolet rays from a fluorescent lamp, discoloration, pollution, and surface deterioration caused by outdoor use are controlled and which is excellent in light resistance and weatherability. SOLUTION: In the laminated film, an ultraviolet ray absorbing layer and a low pollution layer are formed at least on one side of a white base material film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white light-resistant laminated film, and more particularly, to a white light-resistant laminated film having excellent light resistance.
The present invention also relates to a white light-resistant laminated film having excellent anti-staining properties.

[0002]

2. Description of the Related Art Heretofore, as a white film, a film in which white inorganic particles are filled in a polyester resin and a fluorescent whitening agent is used in combination as needed has been often used. For example, Japanese Patent Publication No.
Japanese Unexamined Patent Publication No. 4-1901 and Japanese Patent Publication No. 43-122013 to which calcium carbonate is added are known. Further, a polyester resin having a polyolefin resin added thereto is disclosed in JP-A-63-17 / 1988.
No. 2740 discloses this.

[0003]

However, these conventional white films suffer from a fatal drawback for white films, in that the whiteness, which is a characteristic feature of the conventional white films, is reduced due to deterioration of the polyester resin or polyolefin resin serving as a skeleton due to ultraviolet rays. Therefore, there is a limit in use, especially in outdoor applications.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks, to reduce the discoloration and deterioration of fluorescent lamps due to ultraviolet rays, and to reduce the discoloration, contamination and surface deterioration during outdoor use, and to provide a white light-resistant laminate which is extremely excellent in light resistance and weather resistance. It is to provide a film.

[0005]

Means for Solving the Problems In order to solve the above problems, the white light-resistant laminated film of the present invention is characterized in that at least one surface of a white base film is provided with an ultraviolet absorbing layer and a low-contamination layer. Consisting of

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with preferred embodiments. The white base film referred to in the present invention is a film obtained by incorporating a thermoplastic resin and a resin incompatible therewith or a white inorganic pigment, melt-extrusion, and then biaxially stretching. As the thermoplastic resin, a polyester resin, a polyolefin resin such as polypropylene or polyethylene, a polyamide resin represented by nylon, a polyvinyl chloride resin, a polycarbonate resin, an acrylic resin, a fluororesin, or the like can be used. Among them, polyester resin is preferable from the viewpoint of mechanical strength, dimensional stability and the like. Polyester resin is a generic term for polymers having an ester bond as a main bonding chain, and particularly preferred polyester resins are polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polybutylene-2,6-naphthalate. And so on,
Among them, polyethylene terephthalate can be preferably used in view of quality and economy. This polyethylene terephthalate is used as a main component, and a single core layer may be used. However, a laminated film composed of two layers of a core layer and an outer layer, preferably three layers having outer layers on both sides of the core layer is desirable.

Here, the term "polyethylene terephthalate as the main constituent" means that 70% by weight or more, preferably 80% by weight or more of the resin component constituting the white base film is made of polyethylene terephthalate. Other components that can be mixed with the polyethylene terephthalate are polyester resins other than the above main components, and specifically, various copolymers of polyester are preferable.

As a method for imparting whiteness to the white base film of the present invention, there are a method of adding a resin having poor compatibility with the resin of the main component and a method of containing a white inorganic pigment. Generally, the latter method of containing a white inorganic pigment is widely used.

As the white inorganic pigment, those conventionally used can be used. For example, titanium dioxide, barium sulfate, zinc oxide, calcium carbonate and the like can be preferably used. The amount of the inorganic pigment to be added can be adjusted depending on the type of the pigment in order to obtain the desired whiteness. For example, when obtaining a whiteness of 80% or more of the laminated film after the light resistance deterioration test described in the present application, 7 to 15% by weight of titanium dioxide on the core film side and 2 to 10% on the outer layer.
Contains titanium dioxide by weight. Alternatively, it can be achieved by including 10 to 20% by weight of barium sulfate or calcium carbonate in the core film and 2 to 20% by weight of titanium dioxide in the outer layer.

The white inorganic pigment to be added to the outer layer is preferably one having a small particle size, and the addition amount is preferably smaller than that of the core film because the surface gloss of the white base film can be excellent. . The particle size of the white inorganic pigment is 1 μm or less, preferably 0.5 μm or less,
More preferably, the whiteness is 0.3 μm or less,
It is preferable in terms of surface smoothness.

Regarding the method of adding a resin having poor compatibility with the resin of the main component, for example, in the case of a polyethylene terephthalate film, a resin incompatible with polyethylene terephthalate as a resin component constituting the base film is as follows.
A resin that exhibits a phase-separated structure when formed into a sheet after kneading, and a polyolefin resin can be used as a typical example. Specifically, low density to high density polyethylene, isotactic, atactic, syndiotactic polypropylene, polymethylpentene, polystyrene and the like can be used. These incompatible resins are dispersed and compounded in the above polyethylene terephthalate in the base film. The compounding ratio is usually 3% in consideration of productivity and mechanical strength while utilizing the characteristics of whiteness and low density. % To 30% by weight, preferably 5% to 25% by weight, more preferably 7% to 20% by weight. Such a polyester film in which the incompatible resin is dispersed and blended forms a fine cavity with the incompatible resin as a core by being biaxially stretched.

Also, a fluorescent whitening agent is added to the white base film,
An ultraviolet absorber may be added.

The thickness of the white substrate film of the present invention may be freely set according to the intended use, and is usually 25 to 250 μm.
A range of m is common and desirable. The thickness of the outer layer is desirably 2 μm or more and 50 μm or less, preferably 3 μm or more and 20 μm or less from the viewpoint of whiteness.

In the present invention, the surface of the white base film may be subjected to various discharge treatments, vacuum thin film forming treatment, anchor coating treatment, etc. for the purpose of improving the adhesion between the white base film and the ultraviolet absorbing layer.

In the present invention, an ultraviolet absorbing layer is formed on at least one surface of the white base film. In particular, a preferred ultraviolet absorbing layer in the present invention is a halose hybrid polymer having an acrylic skeleton and a benzotriazole-based ultraviolet absorbing layer. It is obtained by copolymerizing functional groups having functions.

A Hals hybrid polymer having an acrylic skeleton is a hindered amine light stabilizer (HALS: Hin) having an acrylate skeleton and having a functional group at a terminal.
dered Amine Light Stabili
acrylate), and alkyl acrylate and alkyl methacrylate as acrylate (methyl group, ethyl group, n
-Propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, etc.) and a monomer having a crosslinkable functional group, such as a carboxyl group or methylol Groups, acid anhydride groups, sulfonic acid groups, amide groups, or methylolated amide groups, amino groups (including substituted amino groups), alkylolated amino groups,
A monomer having a hydroxyl group, an epoxy group or the like can be exemplified.

Examples of the monomer having the above functional group include acrylic acid, methacrylic acid, itaconic acid, maleic acid,
Fumaric acid, crotonic acid, vinylsulfonic acid, styrenesulfonic acid, acrylamide, methacrylamide, N-methylmethacrylamide, methylolated acrylamide,
Methylolated methacrylamide, diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3
-Aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate,
And the above-mentioned amino group methylolated, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β
-Hydroxypropyl methacrylate, β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, glycidyl acrylate, glycidyl methacrylate, and the like,
It is not necessarily limited to these. Further monomers other than the following, for example, acrylonitrile,
Methacrylonitrile, styrene, butyl vinyl ether, mono- or dialkyl esters of maleic and itaconic acids, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, vinyl pyrrolidone, alkoxy silane having a vinyl group, and unsaturated bond May be used as the copolymerization component.

Examples of the hindered amine light stabilizer having a functional group include ADK STAB LA-82 manufactured by Asahi Denka Co., Ltd.
Reactive types such as LA-87, monomer types such as Hostabin N-20 manufactured by Hoechst Japan Co., Ltd., and Tomisorp 77 manufactured by Yoshitomi Fine Chemical Co., Ltd., and oligomer types such as Uvinyl 5050H manufactured by BSF Japan are preferable. .

The reactive benzotriazole-based monomer having an ultraviolet absorbing ability is not particularly limited as long as it has benzotriazole in the base skeleton and has an unsaturated double bond.
(2'-hydroxy-5'-acryloyloxyethylphenyl) -2H-benzotriazole, 2- (2'-
Hydroxy-5'-methacryloxyethylphenyl)-
2H-benzotriazole, 2- (2'-hydroxy-
3'-tert-butyl-5'-acryloyloxyethylphenyl) -5-chloro-2H-benzotriazole is preferred.

The ratio between the hindered amine light stabilizer and the benzotriazole UV absorbing monomer copolymerized with the acrylate is such that the hindered amine light stabilizer is 1% or less and the benzotriazole UV absorbing monomer is 20% or less based on the acrylate. It is preferable in that the durability of the coating film is maintained. In addition, improvement in adhesion to the base white film,
For the purpose of increasing the hardness of the light-resistant coating film, an isocyanate-based or melamine-based curing agent may be added.

The low contamination layer formed on the ultraviolet absorbing layer is
This is a composite of a Hals hybrid polymer having an acrylic skeleton of an ultraviolet absorbing layer and inorganic fine particles instead of an ultraviolet absorbing agent.

The composite inorganic fine particles are excellent in that colloidal silica prevents contamination and maintains the hardness of the coating film, and the particle size is preferably 20 nm or less from the viewpoint of maintaining transparency.
The addition amount is preferably 10% or less of the Hals hybrid polymer. Further, by adding an isocyanate-based or melamine-based curing agent to the low-staining layer, the hardness of the coating film is increased and the stain resistance is improved.

The ultraviolet absorbing layer is laminated on the substrate film as an organic solvent or an aqueous dispersion, and its thickness is usually in the range of 0.5 to 10 μm, preferably 2 to 6 μm, It is desirable in terms of flexibility and the like.

The low-contamination layer is also laminated on the ultraviolet-absorbing layer as an organic solvent or a water dispersion, and has a thickness of usually 0.5 to 7 μm, preferably 1 to 4 μm. It is preferable in terms of flexibility and the like.

By providing the ultraviolet absorbing layer and the low-contamination layer on the white base film as described above, the whiteness of the white light-resistant laminated film is higher than that of the white base film alone, and particularly, the wavelength is 295 to 450 nm and the illuminance is 100 mW. The effect is remarkable after a test for promoting light resistance deterioration by irradiation with UV light at / cm ² .

[Measurement and Evaluation of Characteristics] (1) Light Resistance Deterioration Acceleration Test UV Deterioration Acceleration Tester (I-Super UV Tester S
Using UV-W131 (manufactured by Iwasaki Electric Co., Ltd.), an irradiation test was performed at a UV illuminance of 100 mW / cm ² and a temperature and humidity of 60 ° C. and 50% RH, and the reflectance, Lab value, and whiteness of the film were evaluated.

(2) Reflectance, Lab value, whiteness Measured using a spectral colorimeter SE2000 manufactured by Nippon Denshoku Co., Ltd. according to JIS L1015. Reflectance is wavelength 5
The value was 50 nm, and the Lab value was a direct reading value. The whiteness is determined by the reflectance R (λ = 450 nm)% and R (λ = 550 nm) of the film at wavelengths of 450 nm and 550 nm.
% From the following equation. Whiteness (%) = 4R (450) -3R (550)

(3) Contamination property Water is slightly sprayed on the surface of the film sample by spraying, and the following contaminated soil is thoroughly sprinkled thereon,
Heat in a hot air oven at 50 ° C for 30 minutes. After removing from the oven and removing the contaminated soil on the surface,
An irradiation test was performed with a V tester, and the contamination was compared. Composition of contaminated soil Humic soil: 38.0 parts by weight Cement: 17.0 〃 Kaolin: 17.0 シ リ カ ゲ ル Silica gel: 17.0 カ ー ボ ン Carbon black: 1.75 第 Ferric oxide: 0.50 〃 Mineral oil: 8. 75〃 The above composition was pulverized and mixed with a ball mill and used as contaminated soil. Judgment of stainability ：: No stain adheres to the film surface. Δ: The film surface is slightly stained. ×: The film surface is clearly stained.

[0029]

The present invention will be described below in more detail with reference to examples. Example 1 A composite extruder comprising a main extruder and a sub-extruder was used, and calcium carbonate having an average particle size of 0.5 μm was added to the main extruder for 10 times.
A polyethylene terephthalate resin containing 5% by weight of titanium dioxide having an average particle diameter of 0.2 μm was previously vacuum-dried at 180 ° C. for 3 hours in a sub-extruder.
The mixture was supplied to two extruders heated to about 300 ° C., extruded from a T-die, and formed into a sheet having a main / sub thickness ratio of 90/10 on a mirror-surface cast drum by an electrostatic application method.

The sheet was guided to a group of rolls heated to 85 to 95 ° C., stretched 3.5 times in the longitudinal direction, and cooled by a group of rolls at 25 ° C. Subsequently, the film was guided to a tenter while holding both ends of the longitudinally stretched film with clips, and 90 to 13
3.6 in the direction perpendicular to the longitudinal direction in an atmosphere heated to 0 ° C.
The film was stretched twice. Thereafter, heat fixation at 230 ° C. is performed in a tenter, and the film is gradually cooled, cooled to room temperature, and wound up to obtain a composite white film having a core thickness of 90 μm, an outer layer thickness of 5 μm each for a cast surface and a non-cast surface, and a total thickness of 100 μm. Was. An ultraviolet absorbing layer (layer A) having the following composition was applied to one surface of the obtained film so that the thickness after application was 4.5 μm, and dried at 120 ° C. for 1 minute. Furthermore, a low-contamination layer (layer B) having the following composition having a thickness of 2.5 μm was formed on the layer A.
m and dried with a hot air drier at 120 ° C. for 1 minute.

After 6 hours of irradiation with the Eye Super UV tester, there was almost no change in color tone, no significant decrease in whiteness was observed before and after the test, and there was no stain in the stain test. Paint composition of ultraviolet absorbing layer (layer A) Benzotriazole-based ultraviolet absorber copolymerized Hals hybrid polymer (Udouble UV-6010 manufactured by Nippon Shokubai Co., Ltd.): 100 parts Curing agent (Sumijur N-3200 manufactured by Sumitomo Haile Urethane Co., Ltd.) : 3 parts Diluent solvent (toluene / methyl ethyl ketone = 1: 1) Paint composition of low-contamination layer (B layer) Organocolloidal silica composite Hals hybrid polymer (Udouble C-3600 manufactured by Nippon Shokubai Co., Ltd.): 100 parts Curing agent (Sumitomo) Sumidur N-3200 manufactured by Bayer Urethane Co., Ltd.): 16 parts Diluent solvent (toluene / methyl ethyl ketone = 1: 1)

Example 2 A single-layer white film having a thickness of 100 μm was produced in the same manner as in Example 1 by using only the main extruder without using the sub-extruder and using the raw materials of the main extruder. An ultraviolet absorbing layer (layer A) having the same composition as in Example 1 was applied to one surface of the obtained film so that the thickness after drying was 4.5 μm, and dried at 120 ° C. for 1 minute. Furthermore, the low-contamination layer of Example 1 (B layer) was formed on the A layer.
To a thickness of 2.5 μm after drying, and 12
It dried at 0 degreeC for 1 minute. As in Example 1, it was excellent in light resistance and contamination.

Example 3 In place of the raw material of the main extruder of Example 1, a raw material mixed to be 89% by weight of polyethylene terephthalate resin, 1% by weight of polyethylene glycol having a molecular weight of 4000, and 10% by weight of polymethylpentene was used. Using a polyethylene terephthalate resin containing 14% by weight of calcium carbonate having an average particle diameter of 0.5 μm in a sub-extruder, a white light-resistant laminated film was produced in the same manner as in Example 1. An ultraviolet absorbing layer (layer A) having the same composition as in Example 1 was applied to one surface of the obtained film so that the thickness after drying was 4.5 μm, and dried at 120 ° C. for 1 minute. Further, the thickness of the low-contamination layer (layer B) of Example 1 after drying was 2.5 μm on layer A.
And dried at 120 ° C. for 1 minute. This is referred to as a third embodiment. As in Example 1, it was excellent in light resistance and contamination.

Example 4 The thickness of the ultraviolet absorbing layer (layer A) of Example 3 after drying was 3 μm.
m and dried at 120 ° C. for 1 minute. Further, the low-contamination layer (layer B) of Example 1 was applied on layer A so that the thickness after drying was 2.5 μm, and dried at 120 ° C. for 1 minute. As in Example 1, it was excellent in light resistance and contamination.

COMPARATIVE EXAMPLE 1 Comparative Example 1 was made of only the multilayer white film obtained in Example 1. In the eye super UV tester 6-hour irradiation deterioration accelerated test, the film turned slightly yellow and the whiteness was greatly reduced. In addition, there were stains on the film surface.

Comparative Example 2 The single-layer white film obtained in Example 2 is referred to as Comparative Example 2. As in Comparative Example 1, the light resistance was poor and the stain resistance was poor.

COMPARATIVE EXAMPLE 3 A single-layer white film obtained in Example 3 is referred to as Comparative Example 3. As in Comparative Example 1, the light resistance was poor and the stain resistance was poor.

Comparative Example 4 Comparative Example 4 is the same as in Example 1 except that the ultraviolet absorbing layer (layer A) was not applied and only the low-contamination layer (layer B) was applied. In the accelerated deterioration test, the film turned slightly yellow and the whiteness was reduced, but there was no stain by the stain test.

Comparative Example 5 An ultraviolet absorbing layer (layer A) of Example 1 was coated at 4.5 μm.
Comparative Example 5 is a case where the low contamination layer is not applied. In the accelerated deterioration test, the film was excellent without discoloration of the film, but in the contamination test, dirt was observed on the film surface.

Table 1 shows the results of evaluating various properties of the white light-resistant laminated films of the above Examples and Comparative Examples.

[0041]

[Table 1]

[0042]

According to the white lightfast laminated film of the present invention, excellent lightfastness and stain resistance can be obtained, whereby the destination display / time display board of an electric signboard, a bus, etc. used indoors and outdoors. It can be widely used for building materials such as wall cloth, surface light source reflectors such as liquid crystal display devices and plasma displays.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI theme coat ゛ (reference) C08L 33/04 C08L 33/04 101/00 101/00 F term (reference) 4F071 AA31X AA32X AA33X AA37X AA46 AB21 AE05 AE09 BB06 BC01 BC17 4F100 AA01A AA01C AA20H AA21H AK01A AK01C AK25B AK25J AL01B AL05A AR00A AR00B AR00C BA03 BA07 BA10A BA10C CA07A CA07C CA18A DE01C EH17A EJ38A GB07 GB08 GB41 JB16A JD09B JL06C JL10A 4J002 BB03W BB03X BB12W BB12X BB17X BC03X BD04W BD12W BG011 BG02W BG041 BG051 BG061 BG071 BH021 BJ001 BQ001 CD191 CF00W CF06W CG00W CL00W DE106 DE136 DE236 DG046 FD096

Claims (5)

[Claims] 1. A white light-resistant laminated film comprising a white base film provided with an ultraviolet absorbing layer and a low-contamination layer on at least one surface. 2. The method according to claim 1, wherein the white base film is a thermoplastic resin,
The white light-resistant laminated film according to claim 1, characterized in that the film is a film obtained by incorporating a resin incompatible with the resin or a white inorganic pigment, performing melt extrusion, and then stretching in a biaxial direction. 3. The method according to claim 1, wherein the ultraviolet absorbing layer and the low-contamination layer are composed of one or more layers, and at least one layer contains an ultraviolet absorbing agent. White light-resistant laminated film. 4. The white color according to claim 1, wherein the ultraviolet absorbing layer is a layer made of a copolymerized acrylic resin in which a functional group having an ultraviolet absorbing ability is incorporated in a Hals hybrid polymer. Lightfast laminated film. 5. The outermost layer of the white light-resistant laminated film is a layer obtained by compounding Hals hybrid polymer with inorganic fine particles and imparting low contamination.
The white light-resistant laminated film according to any one of the above.