JP7222194B2 - protective films and sheets - Google Patents

Description

TECHNICAL FIELD 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 light, water, and the like. Therefore, in applications such as outdoor decorative sheets and posters that require resistance to these (weather resistance), a transparent protective film is provided on the surface layer for the purpose of protecting printed matter.

As materials for the transparent protective film, fluororesins and acrylic resins, which are excellent in weather resistance, and polyolefin resins, which are advantageous in terms of cost, are suitably used. Additives such as hindered amine light stabilizers are commonly used. Incidentally, as a protective film in which a hindered amine light stabilizer is added to a polyolefin resin, there is one described in Patent Document 1, for example.
There are two types of hindered amine light stabilizers: high-molecular type and low-molecular-weight type. Generally, high-molecular type light stabilizers do not move easily in resins such as polyolefins, so they are less likely to bloom or bleed, and the weather resistance of the protective film is maintained for a long period of time. be.

Hindered amine light stabilizers are marketed in roughly three types: NH type, N alkyl type, and NO alkyl type. Although the NH type has a high radical scavenging efficiency, it is basic and may be deactivated by acid rain or the like in actual exposure. Also, the N-alkyl type is generally superior in water resistance to the NH-type and has excellent compatibility with polyolefin resins, but its radical scavenging efficiency is low. In addition, the NO alkyl type exhibits high ability as a light stabilizer because of its low basicity and high radical scavenging efficiency.
Although NO alkyl-type light stabilizers, which are polymer types with low bleeding and high radical scavenging efficiency, are on the market, they are not inexpensive and therefore not widely used.

JP 2017-197639 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a protective film containing a transparent polyolefin resin layer that is excellent in weather resistance and cost performance, and a sheet using the same.

As a result of intensive studies, the present inventors have found that a protective film and a sheet using the same, in which a plurality of types of polymer hindered amine light stabilizers having a specific structure are added to a transparent polyolefin resin at a predetermined ratio, achieve the above-mentioned goals. The present inventors have found that they can achieve this. The term "polymer" means a molecule having a weight average molecular weight of 2000 or more.

（一般式（Ｉ）中、ｋは２から４までの整数であり、ｌは１から８までの整数であり、一般式（Ｉ）に示す化合物の重量平均分子量は２０００以上１００００以下の範囲内である。）

（一般式（ＩＩ）中、Ｒ_１、Ｒ_２、Ｒ_３はそれぞれ独立し、水素原子または炭素数が１から８までのアルキル基を示す。また、一般式（ＩＩ）に示す化合物の重量平均分子量は２０００以上１００００以下の範囲内である。） One aspect 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 is a first hindered amine light represented by the following general formula (I) A stabilizer and a second hindered amine light stabilizer represented by the following general formula (II) are contained, and the weight of the first hindered amine light stabilizer and the second hindered amine light stabilizer The protective film is characterized in that the ratio (first hindered amine light stabilizer/second hindered amine light stabilizer) is in the range of 20/80 to 80/20.

(In general formula (I), k is an integer from 2 to 4, l is an integer from 1 to 8, and the weight average molecular weight of the compound represented by general formula (I) is in the range of 2000 or more and 10000 or less. is.)

(In general formula (II), R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Further, the weight average of the compound represented by general formula (II) The molecular weight is within the range of 2000 or more and 10000 or less.)

According to one aspect of the present invention, there are provided a protective film including a transparent polyolefin resin layer that is excellent in weather resistance and cost, and a sheet using the same.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the cross section of the protective film which concerns on 1st embodiment of this invention. FIG. 4 is a schematic diagram showing a cross section of a decorative sheet according to a second embodiment of the present invention;

[First embodiment]
As a first embodiment of the present invention, the structure of a protective film 10 having a transparent polyolefin resin layer 11 and a surface protective layer 12 will be described with reference to FIG. However, in each drawing described below, the same reference numerals are given to the parts that correspond to each other, and the description of overlapping parts will be omitted as appropriate. Further, the present embodiment exemplifies the configuration for embodying the technical idea of the present invention, and does not specify the material, shape, structure, arrangement, dimensions, etc. of each part as follows. Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.

(Transparent polyolefin resin layer)
The protective film 10 according to this 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, on the 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 polypropylene, polyethylene, polybutene, and α-olefins (eg, propylene, 1-butene, 1-pentene, 1-hexene, 1 -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, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc.) or 2 Copolymers of more than one type, ethylene/vinyl acetate copolymer, ethylene/vinyl alcohol copolymer, ethylene/methyl methacrylate copolymer, ethylene/ethyl methacrylate copolymer, ethylene/butyl methacrylate copolymer, ethylene - Copolymers of ethylene or α-olefins with other monomers, such as methyl acrylate copolymers, ethylene/ethyl acrylate copolymers, and ethylene/butyl acrylate copolymers. Moreover, when aiming at the improvement of the surface strength of the protective film 10, it is preferable to use a highly crystalline polypropylene, for example.

The transparent polyolefin resin layer 11 comprises a hindered amine light stabilizer (first hindered amine light stabilizer) represented by the following general formula (I) and a hindered amine light stabilizer (first hindered amine light stabilizer) represented by the following general formula (II). 2 hindered amine light stabilizer), but especially the condensate of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, shown in formula (III) below. and N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine and 2,4,6-trichloro-1, represented by the following general formula (IV) ,3,5-triazine, a reaction product with N-butyl-1-butanamine, and N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine , a polymer with a reactant of N-butyl-2,2,6,6-tetramethyl-4-piperidinamine.

In general formula (I), k is an integer from 2 to 4, l is an integer from 1 to 8, and the weight average molecular weight of the compound represented by general formula (I) is in the range of 2000 or more and 10000 or less. is within.

In general formula (II), R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Moreover, the weight average molecular weight of the compound represented by the general formula (II) is within the range of 2000 or more and 10000 or less.

The weight average molecular weight of the compound represented by formula (III) is in the range of 2000 or more and 10000 or less.

In general formula (IV), R ₁ , R ₂ and R ₃ represent normal butyl groups, and the weight-average molecular weight of the compound represented by general formula (IV) is in the range of 2,000 to 10,000.

The blending amount of the hindered amine light stabilizer, that is, the total blending amount of the first hindered amine light stabilizer and the second hindered amine light stabilizer is not particularly limited. , and various conditions such as the adhesive layer 20 and the base material 30 to be described later, it is usually in the range of 0.1 to 3 parts by mass with respect to 100 parts by mass of the olefin resin. If the amount of the hindered amine light stabilizer is less than 0.1 part by mass, sufficient weather resistance cannot be imparted to the transparent polyolefin resin layer. However, it is not preferable because there is a possibility that the adhesiveness to the surface protective layer or the like is lowered.

In addition, the first hindered amine light stabilizer, i.e., the hindered amine light stabilizer represented by the general formula (I), and the second hindered amine light stabilizer, i.e., the hindered amine light stabilizer represented by the general formula (II) The weight ratio with the stabilizer (first hindered amine light stabilizer/second hindered amine light stabilizer) is in the range of 20/80 to 80/20. Even if the weight ratio of the first hindered amine light stabilizer and the second hindered amine light stabilizer is less than 20/80 or exceeds 80/20, the transparent polyolefin resin layer has sufficient weather resistance. may not be granted.

Each of the hindered amine light stabilizers described above has a weight average molecular weight within the range of 2,000 or more and 10,000 or less. If the weight-average molecular weight of each hindered amine light stabilizer is less than 2000, it tends to bleed out, which may cause a problem in adhesiveness of the sheet joining the protective film 10 and the substrate 30 . Further, when the weight average molecular weight of each hindered amine light stabilizer exceeds 10,000, it becomes difficult for the light stabilizer to migrate within the polymer, and the weather resistance of the protective film 10 may deteriorate.

The transparent polyolefin resin layer 11 may optionally include other light stabilizers, ultraviolet absorbers, heat stabilizers, antiblocking agents, catalyst scavengers, colorants, light Various additives such as scattering agents and gloss modifiers may be added.
Examples of other light stabilizers include bis(1,2,2,6,6- pentamethyl-4-piperidyl), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3 , 4-butane tetracarboxylate and other hindered amine light stabilizers.

Examples of UV absorbers include, for example, 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-n-octyloxyphenyl)-s-triazine, 2,4,6- tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-s-triazine, 2-[2-hydroxy-4-(2-ethylhexyloxy)phenyl]-4,6-dibiphenyl-s-triazine, Hydroxyphenyl triazine compounds such as 2-[[2-hydroxy-4-[1-(2-ethylhexyloxycarbonyl)ethyloxy]phenyl]]-4,6-diphenyl-s-triazine, 2-(5-chloro-2H -benzotriazole-2-yl)-6-tert-butyl-4-methylphenol, 2-(5-chloro-2-benzotriazolyl)-6-tert-butyl-p-cresol. An ultraviolet absorber is mentioned. Among them, it is preferable to allow the transparent polyolefin resin layer 11 to contain at least one of a hydroxyphenyltriazine-based UV absorber and a benzotriazole-based UV absorber.

The amount of the ultraviolet absorber to be blended is not particularly limited, and is appropriately set according to various conditions such as the thickness of the transparent polyolefin resin layer 11, the adhesive layer 20 and the base material 30, which will be described later, but is usually 100 mass of the olefin resin. It is within the range of 0.1 parts by mass or more and 2 parts by mass or less per part. If the blending amount of the ultraviolet absorber is less than 0.1 part by mass, it may not be possible to impart sufficient weather resistance to the transparent polyolefin resin layer. In addition, when the amount of the UV absorber exceeds 2 parts by mass, the UV absorber bleeds out from the protective film 10, causing problems with the adhesiveness and design of the sheet joining the protective film 10 and the substrate 30. There is In addition, the transparent polyolefin resin layer 11 tends to be noticeably cloudy, which may cause problems in terms of design.

The method for producing the transparent polyolefin resin layer 11 is not particularly limited, and for example, a normal method such as calendar film formation or extrusion film formation is used. A transparent polyolefin resin layer containing can be deposited.
The transparent polyolefin resin layer 11 may be provided with surface unevenness in order to impart designability. Examples of the method of providing unevenness include a method of extruding a transparent polyolefin resin film and then hot embossing, and a method of performing embossing simultaneously with extrusion using a cooling roll provided with unevenness during extrusion.

(Surface protective layer)
The surface protective layer 12 according to the present embodiment is a layer provided to the protective film 10 to provide functions such as weather resistance, scratch resistance, stain resistance, and designability. The material constituting the surface protective layer 12 is not particularly limited, and for example, it can be appropriately selected from resin materials such as urethane, acrylic, acrylic silicone, fluorine, and epoxy resins.
The surface protective layer 12 optionally contains various additives such as ultraviolet absorbers, heat stabilizers, light stabilizers, anti-blocking agents, catalyst scavengers, colorants, light scattering agents, and gloss modifiers. You may As the ultraviolet absorber and the light stabilizer, for example, those applied to the above-described transparent polyolefin resin layer 11 can be used.

The method of forming the surface protective layer 12 is not particularly limited. The surface protective layer 12 may be formed by curing by a method suitable for the material, such as thermal curing, ultraviolet curing, or the like.
Also, the surface protective layer 12 may be provided after the transparent polyolefin resin layer 11 is bonded to the base material 30 described below.

[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 base material 30 are joined to form a decorative sheet 40 will be described with reference to FIG.
The decorative sheet 40 is constructed by bonding the protective film 10 comprising 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 substrate 30 via the adhesive layer 20. . Note that FIG. 2 shows a decorative sheet 40 in which the transparent polyolefin resin layer 11 provided on the protective film 10 and the pattern layer 32 provided on the base material 30 to be described later are bonded via the adhesive layer 20 .

(Original fabric)
The base material 30 includes a raw fabric 31 and a pattern layer 32 provided on one side of the raw fabric 31 .
Examples of raw material 31 include paper such as thin paper, titanium paper, and resin-impregnated paper, synthetic resin 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 non-woven fabric, synthetic paper, metal foil such as aluminum, iron, gold and silver.
The original fabric 31 may be provided with, for example, a primer layer (not shown) on one or both sides of the original fabric 31 in order to supplement the adhesion with the layers adjacent to the original fabric 31, or may be subjected to corona treatment, plasma treatment, Surface treatments such as ozone treatment, electron beam treatment, ultraviolet treatment, and dichromic acid treatment may be applied.

(picture layer)
The pattern layer 32 is, for example, a pattern printed on the raw fabric 31 using ink. The ink used to form the pattern layer 32 may contain a binder, and examples of the binder include nitrocellulose, cellulose, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, and polyester. It can be used singly or appropriately selected from among modified products. Further, they may be water-based, solvent-based, or emulsion-type, and may be one-liquid type or two-liquid type using a curing agent.
As a method of curing the ink used for forming the pattern layer 32, there is a method of curing the ink by irradiation with ultraviolet rays, electron beams, or the like. Among them, the most common method is to use urethane-based ink and cure it with isocyanate.
In addition to these binders, the ink used to form the pattern layer 32 contains, for example, coloring agents such as pigments and dyes contained in ordinary inks, various additives such as extenders, solvents, and light stabilizers. It is Examples of highly versatile pigments include condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, and pearl pigments such as mica.

The method of providing the pattern layer 32 is not particularly limited, and ordinary printing methods such as gravure printing, offset printing, screen printing, flexographic printing, and ink jet printing can be used.
The method of bonding the protective film 10 to the substrate 30 is not particularly limited, and various lamination methods such as heat lamination, extrusion lamination, dry lamination, and sand lamination are used as necessary, for example, via the adhesive layer 20. be able to.
The adhesive layer 20 is not particularly limited. For example, a material that is appropriately selected from resin materials such as urethane, acrylic, acrylic silicon, fluorine, and epoxy and is made into an ink is coated with, for example, gravure coat or micro gravure. It is formed using a usual coating method such as coating, comma coating, knife coating, die coating, and the like.

Regarding the thickness of each layer constituting the decorative sheet 40 according to the present embodiment, the original sheet 31 is 20 μm to 150 μm, the adhesive layer 20 is 1 μm to 20 μm, and the transparent polyolefin resin layer 11 is 20 μm in consideration of printing workability and cost. It is desirable that the thickness of the surface protective layer 12 is 3 μm to 20 μm. Also, the total thickness of the decorative sheet 40 is preferably within the range of 45 μm to 250 μm.

EXAMPLES The present invention will now be described in detail with reference to examples, comparative examples, and reference examples.
<Example 1>
100 parts by mass of a transparent homopolypropylene resin (Prime PP; manufactured by Prime Polymer Co., Ltd.) with 0.5 parts by mass of an ultraviolet absorber (TINUVIN 326; manufactured by BASF Japan Co., Ltd.) and a light stabilizer, the following formula (A ) Light stabilizer (light stabilizer A) (tinuvin 622; manufactured by BASF Japan Co., Ltd.) 0.4 parts by mass, light stabilizer (light stabilizer B) shown in the following formula (B) (Kimasorb 2020; BASF A protective film of Example 1 was obtained by melt extruding a resin composition to which 0.1 part by mass of Japan Co., Ltd. was added to have a thickness of 80 µm.
Next, a pattern layer (thickness: 3 μm) is provided by gravure-printing a wood grain pattern on a polyethylene raw fabric (thickness: 70 μm) having opacifying properties using a two-component urethane ink (V180; manufactured by Toyo Ink Co., Ltd.). The protective film was dry-laminated on the substrate obtained in 1. above via a dry-laminating adhesive (Takelac A540; manufactured by Mitsui Chemicals, Inc.) (thickness: 2 μm). Furthermore, as a surface protective layer, a two-liquid curing polyurethane resin layer composed of acrylic polyol (copolymer of methyl methacrylate and 2-hydroxy methacrylate) and a curing agent (nurate form of hexamethylene diisocyanate) is formed by coating on the protective film (layer thickness 8 μm) to obtain a decorative sheet of Example 1.

<Example 2>
The decorative sheet of Example 2 was prepared in the same manner as in Example 1, except that the amount of light stabilizer A added was 0.3 parts by mass and the amount of light stabilizer B added was 0.2 parts by mass. got
<Example 3>
The decorative sheet of Example 3 was prepared in the same manner as in Example 1 except that the amount of light stabilizer A added was 0.2 parts by mass and the amount of light stabilizer B added was 0.3 parts by mass. got
<Example 4>
The decorative sheet of Example 4 was prepared in the same manner as in Example 1, except that the amount of light stabilizer A added was 0.1 parts by mass and the amount of light stabilizer B added was 0.4 parts by mass. got

<Comparative Example 1>
A decorative sheet of Comparative Example 1 was obtained in the same manner as in Example 1, except that 0.5 parts by mass of light stabilizer A was added as a light stabilizer.
<Comparative Example 2>
A decorative sheet of Comparative Example 2 was obtained in the same manner as in Example 1, except that 0.5 parts by mass of light stabilizer B was added as a light stabilizer.
<Reference example>
In Example 1, the light stabilizer represented by the following formula (C) (light stabilizer C) (tinuvin NOR371; manufactured by BASF Japan Co., Ltd.) 0.5 parts by weight was added as a light stabilizer. A decorative sheet of Reference Example was obtained in the same manner.

The light stabilizer A is a compound having a weight average molecular weight of 3,100 to 4,000.

The light stabilizer B is a compound in which R ₁ , R ₂ and R ₃ are normal butyl groups and the weight average molecular weight is 2600 or more and 3400 or less.

The light stabilizer C is a compound having a weight average molecular weight of 2800 or more and 4000 or less.

<Evaluation>
The weather resistance of the decorative sheets obtained in the above Examples, Comparative Examples and Reference Examples was evaluated by the following method. The evaluation results are shown in Table 1 below.
The appearance of the decorative sheet after the accelerated weather resistance test was visually evaluated according to the following criteria. The accelerated weather resistance test uses an eye super UV tester (SUV-W161; Iwasaki Electric Co., Ltd.), with a black panel temperature of 63 ° C and an illumination of 65 mW / cm ² , (20 hours of UV irradiation + 4 hours of condensation) as one cycle. , 10 cycles (240 hours), 15 cycles (360 hours), and 20 cycles (480 hours).

(Visual evaluation criteria)
○: No change in appearance of the decorative sheet △: Whitening observed on the decorative sheet ×: Cracks observed on the decorative sheet Passed.

As shown in Table 1, the protective films and decorative sheets according to the present embodiment exemplified in Examples 1 to 4 were obtained by adding two types of hindered amine light stabilizers having the above specific structure to the transparent polyolefin resin layer. By mixing at the same ratio, weather resistance equivalent to that of Tinuvin NOR371 (reference example), which is an existing polymeric NO alkyl type hindered amine light stabilizer, is exhibited.

INDUSTRIAL APPLICABILITY The present invention can be used not only for outdoor sheets such as decorative sheets, posters and signs, but also for indoor sheets such as surface materials for fittings and flooring materials.

10 Protective film 11 Transparent polyolefin resin layer 12 Surface protective layer 20 Adhesive layer 30 Base material 31 Original fabric 32 Pattern layer 40 Decorative sheet

Claims (8)

A protective film comprising at least a transparent polyolefin resin layer and a surface protective layer formed on the transparent polyolefin resin layer,
The transparent polyolefin resin layer contains a first hindered amine light stabilizer represented by the following general formula (I) and a second hindered amine light stabilizer represented by the following general formula (II),
The weight ratio of the first hindered amine light stabilizer and the second hindered amine light stabilizer (first hindered amine light stabilizer/second hindered amine light stabilizer) is 20/80 to 80. /20, and
A protective film, wherein the surface protective layer is made of a urethane-based, acrylic, acrylic silicon-based, fluorine-based, or epoxy-based resin material.

(In general formula (I), k is an integer from 2 to 4, l is an integer from 1 to 8, and the weight average molecular weight of the compound represented by general formula (I) is in the range of 2000 or more and 10000 or less. is.)

(In general formula (II), R1, R2, and R3 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. The weight-average molecular weight of the compound represented by general formula (II) is 2,000. It is within the range of 10000 or less.) 2. The protective film according to claim 1, wherein the transparent polyolefin resin layer further contains at least one of a hydroxyphenyltriazine-based UV absorber and a benzotriazole-based UV absorber. The first hindered amine light stabilizer has a structure represented by the following formula (III),
3. The protective film according to claim 1, wherein the second hindered amine light stabilizer has a structure represented by the following general formula (IV).

(The weight average molecular weight of the compound represented by formula (III) is in the range of 2000 or more and 10000 or less.)

(In general formula (IV), R1, R2, and R3 represent normal butyl groups, and the weight-average molecular weight of the compound represented by general formula (IV) is in the range of 2,000 to 10,000.) The transparent polyolefin resin layer contains 2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2'-n-butylmalonate bis(1,2,2,6,6) as a light stabilizer. -pentamethyl-4-piperidyl), or bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate. protective film. 5. The protective film according to any one of claims 1 to 4, wherein the surface protective layer contains the same light stabilizer as the light stabilizer added to the transparent polyolefin resin layer. 3. The protective film according to claim 2 , wherein the surface protective layer contains the same UV absorber as the UV absorber added to the transparent polyolefin resin layer. The weight ratio of the first hindered amine light stabilizer and the second hindered amine light stabilizer (first hindered amine light stabilizer/second hindered amine light stabilizer) is 20/80 to 40. /60. A sheet comprising at least the protective film according to any one of claims 1 to 7 and a substrate.

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