JP2019218508A - Protective film and sheet - Google Patents

Abstract

To provide a protective film including a transparent polyolefin resin layer excellent in weatherproofness with smaller white turbidness that causes deterioration of designability, and also to provide a sheet using the same.SOLUTION: A transparent polyolefin resin layer contains a hydroxyphenyltriazine-based ultraviolet absorber having a structure expressed by a general formula (1). (R-Reach independently represent a hydrogen atom, a methyl group, a phenyl group or an alkoxy group, in which at least two are an alkoxy group having 8-18 carbon atoms, Rand Reach independently represent a hydroxyl group, a methyl group or a hydrogen atom, and Rto Reach independently represent a methyl group or a hydrogen atom.)SELECTED DRAWING: None

Description

  The present invention relates to a protective film and a sheet using the same.

Conventionally, general printed matter does not have high resistance to ultraviolet rays, water, and the like. For this reason, in applications requiring durability (weather resistance) such as outdoor decorative sheets and posters, a transparent protective film is provided on the surface layer for the purpose of protecting printed matter.
As a material for the transparent protective film, in addition to fluororesin and acrylic resin having excellent weather resistance, polyolefins and the like, which are advantageous in terms of cost, are preferably used. Additives are commonly used. For example, hydroxyphenyl triazine compounds have been proposed as ultraviolet absorbers having excellent performance of imparting weather resistance (Patent Documents 1 and 2). However, when a hydroxyphenyltriazine-based UV absorber is applied to a polyolefin, not only the weather resistance of the transparent film differs depending on the structure of the UV absorber, but also the design of printed matter may be reduced due to cloudiness.

US Patent Application Publication No. 2004/0241111 US Pat. No. 6,191,199

  An object of the present invention is to provide a protective film including a transparent polyolefin resin layer which is excellent in weather resistance and has a small cloudiness which is a factor that impairs the design property, and a sheet using the same.

The present inventors have conducted intensive studies and found that a protective film containing an ultraviolet absorber composed of a hydroxyphenyltriazine compound having a specific structure in a transparent polyolefin and a sheet using the same achieve the above-mentioned goals. Invented the invention.
One embodiment of the present invention for solving the above problems is a protective film including at least a transparent polyolefin resin layer, wherein the transparent polyolefin resin layer has a structure represented by the following general formula (1). A protective film characterized by containing a system ultraviolet absorber.

  (In the general formula (1), R1 to R3 each independently represent a hydrogen atom, a methyl group, a phenyl group, or an alkoxy group, and at least two of them are an alkoxy group having 8 to 18 carbon atoms, and R4 and R5 each represent Each independently represents a hydroxyl group or a methyl group or a hydrogen atom, and R6 to R8 each independently represent a methyl group or a hydrogen atom.)

  According to one embodiment of the present invention, there is provided a protective film including a transparent polyolefin resin layer which is excellent in weather resistance and has small cloudiness which is a factor which impairs design properties, and a sheet using the same.

It is a schematic diagram showing a cross section of a protective film according to a first embodiment of the present invention. It is a schematic diagram which shows the cross section of the decorative sheet which concerns on 2nd embodiment of this invention.

[First embodiment]
As a first embodiment of the present invention, a configuration of a protective film 10 in which a surface protective layer 12 is provided on a transparent polyolefin resin layer 11 will be described with reference to FIG. However, in each of the drawings described below, parts that correspond to each other are denoted by the same reference numerals, and descriptions of the overlapping parts will be appropriately omitted. Further, the present embodiment exemplifies a configuration for embodying the technical idea of the present invention, and does not specify the materials, shapes, structures, arrangements, dimensions, and the like of the respective components to the following. The technical concept of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

(Transparent polyolefin resin layer)
The protective film 10 according to the present embodiment includes a transparent polyolefin resin layer 11 and a surface protective layer 12 formed on one side of the transparent polyolefin resin layer 11, that is, an upper layer of the transparent polyolefin resin layer 11. .

  Examples of the olefin resin constituting the transparent polyolefin resin layer 11 according to the present embodiment include, in addition to polypropylene, polyethylene, polybutene, etc., α-olefins (eg, propylene, 1-butene, 1-pentene, 1-hexene, -Heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1 -Eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1 -Pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 1 -Methyl-1-dodecene, 12-ethyl-1-tetradecene, etc.), homopolymerized or copolymerized by two or more types, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methyl As in methacrylate copolymer, ethylene / ethyl methacrylate copolymer, ethylene / butyl methacrylate copolymer, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / butyl acrylate copolymer, etc. Or those obtained by copolymerizing an α-olefin and other monomers. In order to improve the surface strength of the protective film 10, it is preferable to use highly crystalline polypropylene.

  The transparent polyolefin resin layer 11 only needs to contain a hydroxyphenyltriazine-based ultraviolet absorber having a structure represented by the following general formula (1), and an ultraviolet absorber having a structure represented by the following general formula (2) Is more preferable, and in particular, 2,4-bis [2-hydroxy-4- (2-ethylhexyloxy) phenyl)]-6- (4-methoxyphenyl) -s represented by the following formula (3): -Triazines are preferred.

  In the general formula (1), R1 to R3 each independently represent a hydrogen atom, a methyl group, a phenyl group, or an alkoxy group, and at least two of them are an alkoxy group having 8 to 18 carbon atoms, and R4 and R5 are Each independently represents a hydroxyl group or a methyl group or a hydrogen atom, and R6 to R8 each independently represent a methyl group or a hydrogen atom.

  In the general formula (2), R1 and R2 represent an alkoxy group having 8 to 18 carbon atoms, R3 represents an alkoxy group having 1 to 4 carbon atoms, R4 represents a hydroxyl group, and R5 to R8 represent a hydrogen atom.

  The amount of the hydroxyphenyltriazine-based ultraviolet absorber is not particularly limited, and is appropriately set depending on the thickness of the transparent polyolefin resin layer 11 and various conditions such as the adhesive layer 20 and the base material 30 described below. It is in the range of 0.1 part by mass or more and 2 parts by mass or less based on 100 parts by mass of the olefin resin. If the amount of the hydroxyphenyltriazine-based ultraviolet absorber is less than 0.1 part by mass, sufficient weather resistance may not be imparted to the transparent polyolefin resin layer. When the amount of the hydroxyphenyltriazine-based ultraviolet absorber exceeds 2 parts by mass, the transparent polyolefin resin layer has a pronounced white turbidity, and a sheet obtained by bonding the protective film 10 and the base material 30 such as a decorative sheet 40 described later. There may be a problem in the design of the product.

  If necessary, the transparent polyolefin resin layer 11 may be made of, for example, other ultraviolet absorbers not corresponding to the above-described hydroxyphenyltriazine-based ultraviolet absorber, heat stabilizers, light stabilizers, antiblocking agents, catalyst scavengers, coloring agents And various additives such as a light scattering agent and a gloss adjusting agent.

  Examples of other UV absorbers include, for example, 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-n-octyloxyphenyl) -s-triazine, 2,4,4 6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -s-triazine, 2- [2-hydroxy-4- (2-ethylhexyloxy) phenyl] -4,6-dibiphenyl-s- Hydroxyphenyltriazine compounds such as triazine, 2-[[2-hydroxy-4- [1- (2-ethylhexyloxycarbonyl) ethyloxy] phenyl]]-4,6-diphenyl-s-triazine, 2- (5-chloro -2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol, 2- (5-chloro-2-benzotriazo Le) -6-tert-butyl -p- benzotriazole-based ultraviolet absorbents such as cresol.

  Examples of light stabilizers include, for example, bis (1,2,2,6,6-pentamethyl) 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2′-n-butylmalonate -4-piperidyl), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,3 Hindered amine light stabilizers such as 4-butanetetracarboxylate are exemplified.

The method for producing the transparent polyolefin resin layer 11 is not particularly limited, and ordinary methods such as calendar film formation and extrusion film formation are used, and include the above-mentioned olefin resin, hydroxyphenyltriazine-based ultraviolet absorber and various additives. A transparent olefin resin layer can be formed.
The transparent polyolefin resin layer 11 may be provided with surface irregularities in order to impart design properties. Examples of the method of providing the unevenness include a method of extruding a transparent polyolefin resin film followed by hot embossing, and a method of performing embossing simultaneously with extrusion using a cooling roll provided with unevenness during extrusion forming.

(Surface protection layer)
The surface protective layer 12 according to the present embodiment is a layer provided for imparting functions such as weather resistance, scratch resistance, stain resistance, and design to the protective film 10. The material constituting the surface protective layer 12 is not particularly limited, and may be appropriately selected from, for example, resin materials such as urethane, acrylic, acrylic silicon, fluorine, and epoxy.
The surface protective layer 12 contains various additives such as an ultraviolet absorber, a heat stabilizer, a light stabilizer, an anti-blocking agent, a catalyst trapping agent, a coloring agent, a light scattering agent, and a gloss adjusting agent, if necessary. May be. As the ultraviolet absorber and the light stabilizer, for example, those applied to the above-mentioned transparent polyolefin resin layer 11 can be used.

The method for forming the surface protective layer 12 is not particularly limited, and a liquid of the above-described material, for example, a gravure coat, a microgravure coat, a comma coat, a knife coat, a die coat, and the like are applied by a usual method, The surface protective layer 12 may be formed by curing with a method suitable for the material such as heat curing or ultraviolet curing.
Further, the surface protective layer 12 may be provided after the transparent polyolefin resin layer 11 is bonded to a base material 30 described later.

[Second embodiment]
As a second embodiment of the present invention, a configuration in which the protective film 10 according to the first embodiment and the substrate 30 are joined to form a decorative sheet 40 will be described with reference to FIG.
The decorative sheet 40 is configured by joining the protective film 10 including the surface protective layer 12 and the transparent polyolefin resin layer 11, that is, the protective film 10 according to the first embodiment, to the base material 30 via the adhesive layer 20. You. FIG. 2 shows a decorative sheet 40 in which a transparent polyolefin resin layer 11 provided on a protective film 10 and a picture layer 32 provided on a base material 30 to be described later are bonded via an adhesive layer 20.

(Original fabric)
The base material 30 includes an original fabric 31 and a picture layer 32 provided on one surface side of the original fabric 31.
Examples of the raw material 31 include paper such as tissue paper, titanium paper, and resin-impregnated paper; and synthetic resins such as polyethylene, polypropylene, polybutylene, polystyrene, polycarbonate, polyester, polyamide, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and acrylic. Or foams of these synthetic resins, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene-styrene block copolymer rubber, styrene-butadiene-styrene block copolymer It can be arbitrarily selected from rubber such as rubber and polyurethane, organic or inorganic nonwoven fabric, synthetic paper, metal foil such as aluminum, iron, gold and silver.
The raw material 31 may be provided with, for example, a primer layer (not shown) on one or both sides of the raw material 31 in order to supplement the adhesion between the raw material 31 and a layer adjacent to the raw material 31. Surface treatment such as ozone treatment, electron beam treatment, ultraviolet treatment, and dichromic acid treatment may be performed.

(Picture layer)
The pattern layer 32 is, for example, a pattern printed on the material 31 using ink. The ink used to form the picture layer 32 may include a binder, and examples of the binder include nitrified cotton, cellulose, a vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, and polyester. It can be used alone or appropriately selected from the denatured products. Further, they may be any of aqueous, solvent-based and emulsion types, and may be one-pack type or two-pack type using a curing agent.

As a method of curing the ink used to form the picture layer 32, a method of curing the ink by irradiation with ultraviolet light, an electron beam, or the like can be given. Among them, the most common method uses a urethane-based ink and is a method of curing with an isocyanate.
The ink used to form the picture layer 32 includes, in addition to these binders, various additives such as pigments, dyes and other coloring agents, extender pigments, solvents, and light stabilizers, which are contained in ordinary inks. Have been. Examples of highly versatile pigments include pearl pigments such as condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, and mica.
The method of providing the picture layer 32 is not particularly limited, and for example, a normal printing method such as gravure printing, offset printing, screen printing, flexographic printing, and ink jet printing can be used.

The method for bonding the protective film 10 to the base material 30 is not particularly limited, and various lamination methods such as heat lamination, extrusion lamination, dry lamination, and sand lamination via the adhesive layer 20 are used as necessary. be able to.
The adhesive layer 20 is not particularly limited. For example, a material which is appropriately selected from urethane-based, acrylic-based, acryl-silicone-based, fluorine-based, and epoxy-based resin materials to form an ink, such as gravure coat or microgravure It is formed using a usual coating method such as a coat, a comma coat, a knife coat, and a die coat.
Regarding the thickness of each layer constituting the decorative sheet 40 according to the present embodiment, the raw material 31 is 20 μm to 150 μm in consideration of printing workability and cost, the adhesive layer 20 is 0.2 μm to 20 μm, the transparent polyolefin resin layer 11. Is preferably 20 μm to 200 μm, and the surface protective layer 12 is preferably 3 μm to 20 μm. Further, it is preferable that the total thickness of the decorative sheet 40 is in a range of 45 μm to 250 μm.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.
<Example 1a>
100 parts by mass of a transparent homopolypropylene resin (Prime PP; manufactured by Prime Polymer Co., Ltd.) was added to 0.5 parts by mass of a light stabilizer (Tinuvin XT55; manufactured by BASF Japan K.K.) and a hydroxyphenyltriazine-based ultraviolet absorber represented by the following formula: A resin composition to which 0.5 part by mass of the compound shown in (3) (Tinosorb S; manufactured by BASF Japan K.K.) was added was melt-extruded at a thickness of 80 μm to obtain a protective film of Example 1a.

<Example 1b>
It is obtained by gravure printing a wood pattern using a two-component urethane ink (V180; manufactured by Toyo Ink Co., Ltd.) on an opaque polyethylene raw material (thickness: 70 μm) and providing a pattern layer (thickness: 3 μm). Then, the protective film of Example 1a was dry-laminated via a dry laminating adhesive (Takelac A540; manufactured by Mitsui Chemicals, Inc.) (thickness: 2 μm), and an acrylic polyol (methyl methacrylate and A two-component cured polyurethane resin layer composed of a copolymer of 2-hydroxymethacrylate) and a curing agent (nurate of hexamethylene diisocyanate) was applied and formed (layer thickness: 8 μm). Thus, a decorative sheet of Example 1b was obtained.

<Example 1c>
Example 1a was the same as Example 1a except that the addition amount of the compound represented by the following formula (3) (Tinosorb S; manufactured by BASF Japan Ltd.), which is a hydroxyphenyltriazine-based ultraviolet absorber, was 1.5 parts by mass. Similarly, a protective film of Example 1c was obtained.

<Example 1d>
It is obtained by gravure printing a wood pattern using a two-component urethane ink (V180; manufactured by Toyo Ink Co., Ltd.) on an opaque polyethylene raw material (thickness: 70 μm) and providing a pattern layer (thickness: 3 μm). Then, the protective film of Example 1c was dry-laminated via a dry laminating adhesive (Takerac A540; manufactured by Mitsui Chemicals, Inc.) (thickness: 2 μm), and an acrylic polyol (methyl methacrylate and A two-component cured polyurethane resin layer composed of a copolymer of 2-hydroxymethacrylate) and a curing agent (nurate of hexamethylene diisocyanate) was applied and formed (layer thickness: 8 μm). Thus, a decorative sheet of Example 1d was obtained.

<Comparative Example 1a>
A method similar to that of Example 1a, except that in Example 1a, 0.5 parts by mass of a compound represented by the following formula (4) (Adecastab LA-F70; manufactured by ADEKA Corporation) was added as a hydroxyphenyltriazine-based ultraviolet absorber. Thus, a protective film of Comparative Example 1a was obtained.
<Comparative Example 1b>
In Example 1b, a decorative sheet of Comparative Example 1b was obtained in the same manner as in Example 1b, except that the protective film of Comparative Example 1a was used as the protective film.

<Comparative Example 2a>
In the same manner as in Example 1a, except that 0.5 part by mass of a compound represented by the following formula (5) (Tinuvin 1600; manufactured by BASF Japan Ltd.) was added as the hydroxyphenyltriazine-based ultraviolet absorber in Example 1a. A protective film of Comparative Example 2a was obtained.
<Comparative Example 2b>
In Example 1b, a decorative sheet of Comparative Example 2b was obtained in the same manner as in Example 1b except that the protective film of Comparative Example 2a was used as the protective film.

<Comparative Example 3a>
Example 1a was carried out in the same manner as in Example 1a, except that 0.5 parts by mass of a compound represented by the following formula (6) (Siasorb UV1164; manufactured by Sun Chemical Co., Ltd.) was added as the hydroxyphenyltriazine-based ultraviolet absorber. A protective film of Comparative Example 3a was obtained.
<Comparative Example 3b>
A decorative sheet of Comparative Example 3b was obtained in the same manner as in Example 1b, except that the protective film of Comparative Example 3a was used as the protective film in Example 1b.

  The hydroxyphenyltriazine-based ultraviolet absorber used in each of Examples and Comparative Examples has a structure in which R1 to R8 of the following general formula (7) are substituted as shown in Table 1 below. Example 1b corresponds to the hydroxyphenyltriazine-based ultraviolet absorber represented by the general formula (1) defined in the present embodiment.

<Evaluation>
The design properties and weather resistance of the protective films and decorative sheets obtained in the above Examples and Comparative Examples were evaluated by the following methods. The evaluation results of the protective film and the decorative sheet are shown in Tables 2 and 3 below, respectively.

1) Protective film a) Aesthetics / ΔL: L value was used as an index of the turbidity of the protective film. The protective film was placed on black PET (Lumirror 188X30; manufactured by Toray Industries, Inc.), and the L value was measured using a spectrophotometer (x-rite500 series; X-Rite, Inc.). In Example 1a, a protective film containing no ultraviolet absorber was separately prepared as a reference film, the L value was measured in the same manner, and the value obtained by subtracting the L value of the reference film from the L value of the protective film was ΔL. The larger the ΔL, the greater the white turbidity with respect to the reference film.

Visual evaluation 1: The appearance of the protective film was visually evaluated according to the following criteria.
<Visual evaluation 1 evaluation criteria>
：: No difference in white turbidity was observed with reference film ×: White turbidity was noticeably observed with reference film

b) Weather resistance / visual evaluation 2: The appearance of the protective film after the weather resistance acceleration test was visually evaluated according to the following criteria. The weather resistance acceleration test was performed using an I-Super UV tester (SUV-W161; Iwasaki Electric Co., Ltd.) at a black panel temperature of 63 ° C., an illuminance of 65 mW / cm ² and (UV irradiation 20 hours + dew condensation 4 hours) as one cycle. 30 cycles were performed.
<Visual evaluation 2 evaluation criteria>
：: No change in appearance of the protective film ×: Cracks are observed in the protective film

2) Decorative sheet a) Design / visual evaluation 3: The appearance of the decorative sheet was visually evaluated according to the following criteria.
<Evaluation criteria for visual evaluation 3>
：: No difference in appearance was observed from the reference sheet. ×: Whiteness was observed from the reference sheet. However, the reference sheet was prepared separately from the sheet containing no ultraviolet absorber in Example 1b.

b) Weather resistance / visual evaluation 4: The appearance of the decorative sheet after the weather resistance acceleration test was visually evaluated according to the following criteria. The weather resistance acceleration test was performed under the same conditions as in the visual evaluation 2 above.
<Visual evaluation 4 evaluation criteria>
：: The pattern discoloration of the decorative sheet is small. X: The pattern discoloration of the decorative sheet is remarkably observed.

  As shown in Tables 2 and 3, the protective film and the decorative sheet according to the present embodiment exemplified in Examples 1a to 1d include a hydroxyphenyltriazine-based ultraviolet absorber having a specific structure in the transparent polyolefin resin layer. By applying the composition, it has little turbidity, is excellent in designability, and is excellent in weather resistance.

  INDUSTRIAL APPLICABILITY The present invention can be used not only as a sheet used outdoors such as a decorative sheet, a poster, and a sign, but also as an indoor sheet such as a surface material of a fitting and a floor material.

DESCRIPTION OF SYMBOLS 10 Protective film 11 Transparent polyolefin resin layer 12 Surface protective layer 20 Adhesive layer 30 Base material 31 Raw material 32 Picture layer 40 Decorative sheet

Claims (5)

A protective film including at least a transparent polyolefin resin layer,
A protective film, wherein the transparent polyolefin resin layer contains a hydroxyphenyltriazine-based ultraviolet absorber having a structure represented by the following general formula (1).

(In the general formula (1), R1 to R3 each independently represent a hydrogen atom, a methyl group, a phenyl group, or an alkoxy group, and at least two of them are an alkoxy group having 8 to 18 carbon atoms, and R4 and R5 each represent Each independently represents a hydroxyl group or a methyl group or a hydrogen atom, and R6 to R8 each independently represent a methyl group or a hydrogen atom.)   The protective film according to claim 1, wherein the protective film further includes a surface protective layer formed on the transparent polyolefin resin layer. The protective film according to claim 1, wherein the ultraviolet absorber has a structure represented by the following general formula (2). 4.

(In the general formula (2), R1 and R2 represent an alkoxy group having 8 to 18 carbon atoms, R3 represents an alkoxy group having 1 to 4 carbon atoms, R4 represents a hydroxyl group, and R5 to R8 represent a hydrogen atom.) The said ultraviolet absorber has a structure shown by following formula (3), The protective film of Claim 3 characterized by the above-mentioned.

  A sheet having a structure in which the protective film according to any one of claims 1 to 4 is joined to a substrate.

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