JP5067118B2 - Decorative sheet - Google Patents

Description

  The present invention relates to a decorative sheet that is used as a decorative sheet by being bonded to the surface of, for example, a wooden board, an inorganic board, or a metal plate with an adhesive.

  For example, a decorative sheet is widely used as a decorative plate for interior decoration of a house. As a decorative sheet, a decorative sheet made of a vinyl chloride resin is most common. However, the decorative sheet made of vinyl chloride resin has problems such as generation of hydrogen chloride gas and dioxin that cause acid rain during incineration, and bleeding out of the added plasticizer. Special considerations are necessary for the handling. Therefore, a decorative sheet that does not use a vinyl chloride resin is desired.

  Examples of such decorative sheets include resins such as polyethylene, polypropylene, polyethylene terephthalate, ethylene vinyl alcohol, and acrylic, and decorative sheets using the copolymer. Among them, polypropylene was used because it has the appropriate flexibility, abrasion resistance, scratch resistance, heat resistance, chemical resistance, post-processing properties, transparency, etc. required for decorative sheets and can be manufactured at low cost. Many decorative sheets are shown. Some of these decorative sheets have a single layer, but most have a laminated structure of two or more layers from the viewpoint of design.

  As a decorative sheet using polypropylene, for example, it has a laminated structure of two or more layers, and stress concentration is suppressed by using an ethylene-based resin in which an adhesive component is added to at least one layer, thereby improving the peel strength. Such a polyolefin-based decorative sheet is shown (Patent Document 1). However, in the decorative sheet of Patent Document 1, the peel strength after the heat history may be lowered.

Therefore, a decorative sheet using a polypropylene resin instead of the ethylene resin is disclosed (Patent Document 2).
Japanese Patent No. 3185590 JP 2001-353828 A

However, in the decorative sheet of Patent Document 2, the effect of relaxing the stress is reduced due to the high rigidity of the polypropylene resin and the progress of crystallization of polypropylene during heating, and sufficient peel strength may not be obtained. It was.
In order to avoid problems such as rigidity, an ethylene-based elastomer that is incompatible with polypropylene is also added to the polypropylene resin as appropriate. Has not reached.
Therefore, the present invention provides a decorative sheet having excellent peel strength even after heat history.

  The decorative sheet of the present invention is a decorative sheet in which at least an anchor coat layer and two or more transparent resin layers mainly composed of polypropylene are sequentially laminated on a base sheet, Among them, the transparent resin layer on the side in contact with the anchor coat layer is composed of 60 to 90 parts by mass of polypropylene resin (a) and 40 to 10 parts by mass of ethylene / α-olefin copolymer resin (b) (however, (a) and (b )) And a block copolymer (c) having a crystalline ethylene block (1) to 40 parts by mass.

In the decorative sheet of the present invention, the block copolymer (c) having a crystalline ethylene block is a triblock copolymer in which a crystalline ethylene block, an ethylene / butylene block, and a crystalline ethylene block are successively connected. Preferably there is.
The melt flow rate of the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b) is preferably 3 to 70 times the larger value.
The two or more transparent resin layers are preferably transparent resin layers laminated by a heat-dissolving coextrusion laminating method using a T die.
Of the two or more transparent resin layers, 0.1 to 2.0 parts by mass of the unsaturated carboxylic acid or the anhydride is graft-polymerized on the transparent resin layer in contact with the anchor coat layer. It is preferable.

  The decorative sheet of the present invention has excellent peel strength even after heat history.

  In the decorative sheet of the present invention, at least an anchor coat layer and two or more transparent resin layers are sequentially laminated on the base sheet, and the transparent resin layer on the side in contact with the anchor coat layer is made of polypropylene resin (a ), An ethylene / α-olefin copolymer resin (b), and a block copolymer (c) having a crystalline ethylene block (hereinafter referred to as a block copolymer (c)).

[First Embodiment]
Hereinafter, 1st Embodiment which is an example of the decorative sheet of this invention is described based on FIG.
As shown in FIG. 1, the decorative sheet 1 of the present embodiment has a pattern layer 12, an anchor coat layer 13, and a first transparent resin layer 14 mainly composed of polypropylene (hereinafter, transparent resin) on a base sheet 11. Layer 14) and a second transparent resin layer 15 (hereinafter referred to as transparent resin layer 15) are sequentially laminated.

(Base material sheet)
The material of the base sheet 11 is not particularly limited. For example, polypropylene, polyethylene, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), polymethacrylic acid Non-methyl, polymethyl acrylate, polybutyl acrylate, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, polyamide, nylon 6, nylon 66, etc. A vinyl chloride resin material may be mentioned.
Of these, polyolefin materials such as polypropylene and polyethylene are preferable from the viewpoint of recyclability. In addition, the base sheet 11 made of a polypropylene material is particularly preferable because most of the components of the decorative sheet 1 are made of a polypropylene material.

  Moreover, you may add additives, such as an inorganic pigment, antioxidant, a light stabilizer, and an antiblocking agent, in the said resin material. The additive may be used alone or in combination of two or more.

  In addition, when the base sheet 11 is formed by the T-die extrusion method, the synthetic resin material for forming the base sheet 11 is directly colored with a concealing colorant such as a dye or pigment. It is good also as the base material sheet 11 which extrude | pushed out from T-die in the heat-melting state, and provided concealment property. Thereby, base materials, such as a wooden board, an inorganic board, and a metal plate, on which the decorative sheet 1 is bonded, can be made invisible from the surface of the decorative sheet 1. However, this is not the case when it is desired to utilize the texture of the base material to be bonded.

The coloring method of the base material sheet 11 in forming the base material sheet 11 by the T-die extrusion method is not particularly limited, and examples thereof include a dry color method and a master batch method.
The dry color method is a method in which a fine powdery colorant obtained by treating a pigment with a dispersion aid or a surfactant is directly mixed in a synthetic resin material for forming the base sheet 11 and colored. is there.
The master batch method is a method of preparing a master batch pellet in which a synthetic resin material for forming the base sheet 11 and a high-concentration pigment are melt-kneaded and pre-dispersed in advance, and further, the master batch pellet, In this method, an uncolored synthetic resin material for forming the base sheet 11 is dry blended in an extrusion hopper.

  As the pigment used for coloring the base sheet 11, pigments usually used for coloring decorative sheets can be used. In particular, when considering heat resistance and weather resistance, titanium oxide, ultramarine blue, cadmium pigment, oxidation Inorganic pigments such as iron are preferred. Examples of organic pigments include phthalocyanine pigments and quinacridone pigments. The ratio of the pigment to the resin used for film formation of the base sheet 11 and the hue may be appropriately determined in view of the degree of concealment and design properties.

Further, a master batch pallet in which a synthetic resin material for forming the base sheet 11 colored by the above method is formed, and a high concentration pigment is melt-kneaded and pre-dispersed in a resin having different flow characteristics from the synthetic resin material, wood flour The base material sheet 11 may be colored and patterned by adding glass powder or the like, heating and melting, and extruding to form the base material sheet 11.
Moreover, even if it is a case where the base material sheet 11 is formed into a film by the calendar method, coloring and a pattern can be given to the base material sheet 11 using the method similar to the above.

(Pattern layer)
The pattern layer 12 is a layer that imparts design properties to the decorative sheet 1. By providing the pattern layer 12, the design can be improved.
Although the formation method of the pattern layer 12 is not specifically limited, For example, well-known printing methods, such as gravure printing, intaglio printing, flexographic printing, silk printing, electrostatic printing, and inkjet printing, are mentioned. Moreover, well-known ink can be used also about the ink used for the said printing method. For example, coloring agents such as dyes or pigments, extender pigments, etc. are added to the vehicle, and plasticizers, stabilizers, waxes, greases, drying agents, curing agents, thickeners, dispersants, fillers, etc. are optionally added. Ink that is sufficiently kneaded with a solvent, a diluent, or the like.

As a method for forming the pattern layer 12, a pattern layer is formed on an arbitrary transfer base sheet different from the base sheet 11 by the printing method or the like, and then a heat laminating method, a dry laminating method, or a wet laminating method. A method of transferring the pattern layer onto the base material sheet 11 by bonding the base material sheet for transfer and the base material sheet 11 by a method, an extrusion laminating method, etc., and then peeling the base material sheet for transfer is used. You can also
Further, a masking layer (a layer without a special pattern) that prevents the base material from being seen may be provided instead of the pattern layer 12, or the masking layer and the pattern layer may be used in combination. The masking layer can be formed by the same method as that for the pattern layer 12.

(Anchor coat layer)
As the material of the anchor coat layer 13, a non-vinyl chloride resin material may be used, and a two-component curable urethane resin having a urethane bond obtained by a reaction between a polyol component and an isocyanate component is preferably used.
As the polyol component, polyester polyol or polyester polyurethane polyol is preferably used.
As the isocyanate component, those containing at least one of hexamethylene diisocyanate and isophorone diisocyanate are preferably used.
The formation method of the anchor coat layer 13 is not particularly limited, and a gravure method (gravure printing method, gravure coating method) is preferably used.

(First transparent resin layer)
The transparent resin layer 14 mainly plays a role of improving the adhesion between the transparent resin layer 15 and the anchor coat layer 13 (the base sheet 11 side of the decorative sheet 1).
The transparent resin layer 14 is a layer mainly composed of polypropylene, and contains a polypropylene resin (a), an ethylene / α-olefin copolymer resin (b), and a block copolymer (c).

  When the transparent resin layer 14 contains the polypropylene resin (a), the adhesion strength between the transparent resin layer 14 and the transparent resin layer 15 is increased. Even if a resin whose main component is a material other than the polypropylene resin (a) is used for the transparent resin layer 14, the crystallinity is extremely lowered, or an adhesive component such as a tackifier is added. However, in many cases, the heat resistance of the decorative sheet is very low, and the peel strength after the heat history is greatly reduced.

  Examples of the polypropylene resin (a) include a homopropylene resin obtained by polymerizing propylene alone, a random propylene resin or a block polypropylene resin obtained by copolymerizing propylene and ethylene. Among them, the random propylene resin is preferable because the crystallinity and the elastic modulus are lower than those of the homopropylene resin, and the effect of dispersing and absorbing the peeling stress acting on the base sheet 11 is easily increased.

Moreover, in the transparent resin layer 14, the performance which relieve | moderates the peeling stress of the transparent resin layer 14 becomes high by alloying ethylene-alpha olefin copolymer resin (b) incompatible with a polypropylene resin (a). .
Examples of the α-olefin of the ethylene / α-olefin copolymer resin (b) include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-dodecene and the like. Of these, propylene, 1-butene and 1-hexene are preferable.
Specific examples include Tuffmer P series manufactured by Mitsui Chemicals.

Moreover, the compatibility of polypropylene resin (a) and ethylene-alpha olefin copolymer resin (b) improves the transparent resin layer 14 by containing a block copolymer (c).
The block copolymer (c) is a block copolymer having at least a crystalline ethylene block. However, the crystalline ethylene block means an ethylene block in which ethylene is continuously polymerized at least 10 or more, preferably several tens or more continuously.

Examples of the block copolymer (c) having a crystalline ethylene block include, for example, a triblock copolymer (SEBC) in which a styrene block, an ethylene / butylene block, and a crystalline ethylene block are successively connected, and a crystalline ethylene block and ethylene. -A triblock copolymer (CEBC) in which a butylene block and a crystalline ethylene block are successively connected is exemplified. Of these, CEBC is particularly preferable. CEBC has an ethylene / butylene block portion that is easily compatible with the polypropylene resin (a) and a crystalline ethylene block portion that is easily compatible with the ethylene / α-olefin copolymer resin (b). The effect of increasing the compatibility with the ethylene-α-olefin copolymer resin (b) is high.
Specific examples of the block copolymer (c) include Dynalon 4600P (SEBC type) and Dynalon 6200P (CEBC type) manufactured by JSR Corporation.

The content of each component in the transparent resin layer 14 is such that the polypropylene resin (a) is 60 to 90 parts by mass, and the ethylene-α-olefin copolymer resin (b) is 40 to 10 parts by mass (provided that the polypropylene resin (a) And the ethylene-α-olefin copolymer resin (b) are 100 parts by mass), and the block copolymer (c) is 1 to 40 parts by mass.
When the polypropylene resin (a) is 60 parts by mass or more, sufficient cohesive force is obtained, and the transparent resin layer 14 having a good quality is obtained.
When the ethylene / α-olefin copolymer resin (b) is 10 parts by mass or more, the release stress relaxation performance of the transparent resin layer 14 is sufficiently obtained.
If the block copolymer (c) is 1 part by mass or more, the decorative sheet 1 having excellent peel strength after heat history can be obtained. Further, when the block copolymer (c) is 40 parts by mass or less, the above-described effects due to the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b) can be sufficiently obtained. Moreover, it is preferable that content of a block copolymer (c) is 1-20 mass parts. Even if the block copolymer (c) exceeds 20 parts by mass, the obtained effect is not greatly improved.

  The thickness of the transparent resin layer 14 is preferably 4 to 30 μm. If the thickness of the transparent resin layer 14 is 4 μm or more, the effect of relaxing the peeling stress can be sufficiently obtained. Moreover, even if the thickness of the transparent resin layer 14 exceeds 30 μm, the peel strength does not change greatly.

The melt flow rate of the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b) is preferably 3 to 70 times the larger melt flow rate with respect to the smaller melt flow rate. . The ratio of the melt flow rate is more preferably 3 to 30 times. However, the melt flow rate (unit: g / 10 minutes) in the present invention means a value measured according to ISO 1133, and the polypropylene resin (a) has a load of 21.18 N, a temperature of 230 ° C., ethylene · The α-olefin copolymer resin (b) is a value measured at a load of 21.18 N and a temperature of 190 ° C.
If the ratio of the melt flow rate is 3 times or more, it is easy to prevent the ethylene / α-olefin copolymer resin (b) from being finely dispersed in the polypropylene resin (a), and has the ability to relieve the peeling stress. It is easy to get enough. Moreover, if the ratio of the melt flow rate is 70 times or less, a polypropylene island (a) and an ethylene / α-olefin copolymer resin (b) are likely to have a sea-island structure in which islands are sufficiently dispersed, and the peeling stress is relieved. Sufficient performance is easily obtained.

  The transparent resin layer 14 can be formed by a known method such as a dry laminating method or a sand laminating method, but it is particularly preferable to laminate the transparent resin layer 14 together with the transparent resin layer 15 by a heat-melt coextrusion laminating method using a T die. According to this method, the transparent resin layer 14 and the transparent resin layer 15 can be laminated at the same time without using an adhesive or the like, and the decorative sheet 1 can be efficiently manufactured. Moreover, according to this method, the adhesion strength at the interface between the transparent resin layer 14 and the transparent resin layer 15 both having polypropylene as a main component becomes very strong. Furthermore, when performing the heat-melt coextrusion lamination, the surface of the decorative sheet 1 (the surface of the transparent resin layer 15) is provided in advance on the cooling roll by providing a design in which the design shape and the unevenness to be applied to the decorative sheet 1 are reversed. It is also possible to give a concave pattern.

The transparent resin layer 14 is preferably graft-polymerized with 0.1 to 2.0 parts by mass of an unsaturated carboxylic acid or the anhydride.
Examples of the unsaturated carboxylic acid or the anhydride include acrylic acid, methacrylic acid, maleic acid, phthalic acid, citraconic acid, itaconic acid, and anhydrides thereof, and maleic anhydride is particularly preferable.

  By graft polymerization of the unsaturated carboxylic acid or the anhydride, a polar group is introduced on the surface of the transparent resin layer 14 and the adhesion strength between the anchor coat layer 13 (base sheet 11 side) and the transparent resin layer 14 is improved. Can be made. Since polypropylene is a nonpolar resin, in order to develop high adhesion strength by extrusion lamination, the extrusion temperature is increased to nearly 300 ° C and oxidation is performed using oxygen in the air, or ozone treatment is performed. It is necessary to introduce a polar group. Therefore, if a polar group is introduced in advance with maleic acid or the like, the adhesion strength can be increased without performing extrusion lamination under the above conditions. If a method in which polar groups are preliminarily graft-polymerized is used, it is possible to prevent the amount of treatment from depending on the speed of the laminate in the method of introducing polar groups by oxidation using oxygen in the air or by blowing ozone.

  The graft polymerization amount of the unsaturated carboxylic acid or the anhydride is particularly preferably 0.1 to 2.0 parts by mass. When the graft polymerization amount is 0.1 parts by mass or more, the polar group is sufficiently introduced, and the adhesion strength between the anchor coat layer 13 (base sheet 11 side) and the transparent resin layer 14 is easily improved. Further, when the graft polymerization amount is 2.0 parts by mass or less, it is easy to prevent the polymer from being decomposed and the resin component in the transparent resin layer 14 from becoming brittle or yellowing.

(Second transparent resin layer)
The transparent resin layer 15 plays a role of improving the scratch resistance, abrasion resistance, chemical resistance, and the like of the decorative sheet 1, protecting the pattern layer 12, and improving the design.
The transparent resin layer 15 is made of a material mainly composed of polypropylene, for example, a homopropylene resin obtained by polymerizing propylene alone, a random propylene resin or a block polypropylene obtained by copolymerizing propylene and ethylene. Resin. Among these, when importance is attached to scratch resistance, wear resistance, and resistance to thermal history, homopolypropylene obtained by polymerizing propylene alone is preferably used. Homopolypropylene has higher crystallinity and higher numerical values such as elastic modulus than random polypropylene and block polypropylene, so that scratch resistance and wear resistance are improved. In addition, homopolypropylene resin has a particularly high melting point and softening point among polypropylene resins, and in particular, the homopolypropylene resin obtained by polymerization using a Ziegler-Natta catalyst has a melting point of 160 ° C. or higher, and thus has higher resistance to thermal history. .

  In addition, when emphasizing processability and transparency such as bending of the decorative sheet 1 bonded to a wooden substrate or steel plate, 90 to 99 parts by mass of propylene, ethylene, 1-butene, 1-hexene, 1 -Random polypropylene component obtained by random copolymerization of one or more selected from the group consisting of octene, 4-methyl-1-pentene, etc., and 10 to 1 part by mass (the total amount is 100 parts by mass), and / or atactic A polypropylene resin into which a large amount of a polypropylene component is intentionally introduced is preferably used. Such a polypropylene resin generally has a small degree of crystallinity of a molded product and is excellent in flexibility and transparency.

Moreover, you may make the transparent resin layer 15 contain various rubber components in order to improve a softness | flexibility, transparency, etc.
Examples of the rubber component include isoprene rubber, butadiene rubber, butyl rubber, α-olefin copolymer rubber, chloroprene rubber, epichlorohydrin rubber, acrylic rubber, urethane rubber, silicone rubber, fluorine rubber, styrene butadiene rubber, chlorosulfonated polyethylene rubber, and nitrile. Examples thereof include rubber and polysulfide rubber. However, depending on the type of the material of the transparent resin layer 15, it is necessary to sufficiently consider that it may be a factor that hinders transparency.
It is preferable to use a rubber component having as high a thermal stability as possible and a high value such as a glass transition point, a melting point, and a Vicat softening point. In addition, it is necessary to use materials in consideration of the influence on scratch resistance, transparency, and the influence of precipitation (bleed out) of various additives described later.

  Moreover, in order to improve the functionality of the decorative sheet, the transparent resin layer 15 includes a heat stabilizer, a flame retardant, an ultraviolet absorber, a light stabilizer, a nucleating agent, an antiblocking agent, a catalyst supplement, and the like as necessary. May be added as appropriate.

  The thickness of the transparent resin layer 15 is preferably 30 to 200 μm. If the thickness of the transparent resin layer 15 is 30 μm or more, various physical properties such as scratch resistance, abrasion resistance, and chemical resistance of the decorative sheet 1 are easily improved. Moreover, if the thickness of the transparent resin layer 15 is 200 micrometers or less, the production efficiency of the decorative sheet 1 is high and it is excellent in economical efficiency.

[Second Embodiment]
Next, 2nd Embodiment which is another example of the decorative sheet of this invention is described based on FIG.
As shown in FIG. 2, the decorative sheet 2 includes a pattern layer 12, an anchor coat layer 13, a transparent resin layer 14 and a transparent resin layer 15 mainly composed of polypropylene, and a surface protective layer 16 on a base sheet 11. They are sequentially stacked. A concave pattern 17 is formed between the transparent resin layer 15 and the surface protective layer 16, and the concave pattern 17 is filled with ink 18.
Further, a primer coat layer 19 is formed on the back surface 11 a side of the base sheet 11.
The same components as those of the decorative sheet 1 in the decorative sheet 2 are denoted by the same reference numerals and description thereof is omitted.

(Surface protective layer)
The surface protective layer 16 is formed on the outermost layer of the decorative sheet 2 as a layer that plays a role of improving the design properties and various physical properties of the decorative sheet 2.
As the material for the surface protective layer 16, materials such as acrylic, ester, and urethane are preferably used. Moreover, as a hardening form, the method of using isocyanate curable type, an ultraviolet curable type, an electron beam curable type, etc. independently, or the method of using them together is mentioned.
As a method for forming the surface protective layer 16, a known technique may be used, for example, a gravure coating method.

  The thickness of the surface protective layer 16 is preferably 3 to 20 μm. If the thickness of the surface protective layer 16 is 3 μm or more, it is easy to obtain the effect of improving the design properties and various physical properties. Moreover, if the thickness of the surface protective layer 16 is 20 micrometers or less, it is excellent in economical efficiency.

(Concave pattern)
The concave pattern 17 plays a role of improving the feel of the surface of the decorative sheet 2 and the design. The shape of the recessed pattern 17 is not particularly limited, and examples thereof include a triangular cross section as shown in FIG.
Further, the recessed pattern 17 may be filled with ink 18. A known ink can be used as the ink 18.

(Primer coat layer)
The primer coat layer 19 is a layer formed in order to increase the adhesion between the decorative sheet 2 and the adherend base material such as wood, inorganic, or metal to be bonded.
As a material for the primer coat layer 19, an isocyanate curable polyester material is preferably used. Further, in order to prevent blocking when the decorative sheet 2 is rolled (a phenomenon in which the laminated decorative sheets are too close to each other and are difficult to peel off), the primer coat layer 19 has a number average particle diameter. It is preferable to add an inorganic granular material such as silica having a thickness of several μm.
The primer coat layer 19 can be formed by a known method. For example, a layer of about 1 μm can be formed by a gravure coating method.

The decorative sheet of the present invention described above has excellent peel strength even after heat history.
This is because the block copolymer (c) contained in the transparent resin layer 14 functions as a compatibilizing material for the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b). It is believed that there is.
Since the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b) are incompatible, they are in a continuous sea-island state immediately after being melt-kneaded by an extruder or the like and then cooled and solidified. However, when the crystallization of the polypropylene resin (a) proceeds due to the subsequent heat history, since the ethylene / α-olefin copolymer resin (b) has many amorphous components, the crystallization hardly occurs. Dissociation (craze) occurs at the sea-island structure interface between a) and the ethylene / α-olefin copolymer resin (b), which causes a decrease in cohesive force and a decrease in peel strength. Since the block copolymer (c) can improve compatibility with the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b), it can suppress the occurrence of dissociation (craze) due to thermal history. As a result, it is considered that the peel strength after the thermal history of the decorative sheet can be kept high.
Moreover, the effect of suppressing the whitening phenomenon which arises at the time of a bending process is also acquired by suppressing generation | occurrence | production of the dissociation (crazing) of the interface of the said sea-island structure.

Note that the decorative sheet of the present invention may be configured not to include the pattern layer 12 when it is desired to make use of the material feeling of the base material to be bonded, or when the base sheet 11 is colored and patterned. .
Further, a pattern layer having the same configuration as the pattern layer 12 may be provided on the surface 11 a side of the base sheet 11.
Moreover, the transparent resin layer 15 may have a laminated structure of two or more layers as long as the physical properties such as peel strength, design properties, scratch resistance, abrasion resistance, and chemical resistance of the decorative sheet are not excessively deteriorated. Good.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.
[Example 1]
As the base material sheet 11, a random polypropylene resin (100 parts by mass) with 4% ethylene content, an inorganic pigment (6 parts by mass), a phenol-based antioxidant (0.2 parts by mass), a hindered amine light stabilizer (0. 3 parts by weight) and a sheet obtained by melt-extruding a resin obtained by adding an anti-blocking agent (0.2 parts by weight), and after applying corona treatment to the surface, the pattern ink is printed by gravure printing. A wood grain pattern was applied using (trade name: Lamister, manufactured by Toyo Ink Manufacturing Co., Ltd.) to form a pattern layer 2. Next, a two-component curable urethane anchor coating agent (manufactured by Mitsui Chemicals Polyurethane Co., Ltd .; Takerak (main agent) and Takenate (hardening agent)) is coated on the wood grain pattern layer 2 by a gravure printing method. The anchor coat layer 3 was formed by coating at about 1 μm.
Next, resin A blended with the composition shown in Table 1 and 0.3 parts by mass of maleic anhydride was melt-kneaded and soft polypropylene resin (manufactured by Prime Polymer Co., Ltd., trade name: Prime TPO, semi-rigid) Homotype) 100 parts by weight, 0.2 parts by weight of Irganox 1010 (manufactured by Ciba Japan) as a phenolic antioxidant, 0.1 parts by weight of Irgafos 168 (manufactured by Ciba Japan) as a phosphorous antioxidant Part, 0.5 parts by mass of Tinuvin 783 (manufactured by Ciba Japan Co., Ltd.) as a hindered amine light stabilizer, and 0.5 parts by mass of Tinuvin 326 (manufactured by Ciba Japan Co., Ltd.) as a benzotriazole-based UV absorber were added. Resin B was prepared. Thereafter, the resin A and the resin B are formed on the surface of the anchor coat layer 3 by a T-die coextrusion laminating method at an extrusion temperature of 230 ° C., the resin A is the first transparent resin layer 14 (thickness 15 μm), and the resin B is The decorative sheet 1 was obtained by laminating the second transparent resin layer 15 (thickness: 65 μm).

[Examples 2 to 4]
A decorative sheet was obtained in the same manner as in Example 1 except that the composition of the resin A was changed as shown in Table 1.

[Comparative Examples 1-3]
A decorative sheet was obtained in the same manner as in Example 1 except that the composition of Resin A was changed as shown in Table 2. In addition, in the comparative example 1 in Table 2, it has shown that the 1st transparent resin layer is not provided.

The decorative sheets obtained in the examples and comparative examples were evaluated by the methods described below. The peel strengths in [1] to [3] were measured at a peel rate of 50 mm / min using Tensilon (manufactured by A & D Co., Ltd.).
[1] The peel strength in an atmosphere at 23 ° C. was measured.
[2] The peel strength after the obtained decorative sheet was heat-treated in an oven (90 ° C., 72 hours) was measured.
[3] The surface of the transparent resin layer 15 (layer formed from the resin B) of the obtained decorative sheet is coated with a surface protective layer having a thickness of 6 μm (trade name: UC Clear, manufactured by Dainippon Ink & Chemicals, Inc.). After that, using a weathering tester (Daipura Intes Co., Ltd., trade name: Daipla Metal Weather), irradiation for 20 hours with an illuminance of 70 mW / cm ² (wavelength: 300 to 400 nm) and a black panel temperature of 53 ° C., 4 The peeling strength after 96 hours was measured by repeating the time dew condensation mode.
[4] After the obtained decorative sheet is bonded to a steel sheet having a thickness of 0.5 mm, the degree of whitening of the bent portion when 1R bending is performed in an environment of 5 ° C. is based on the following evaluation criteria. evaluated. In order to activate the adhesive and improve the adhesion between the adhesive and the decorative sheet during bonding onto the steel sheet, the steel sheet coated with the adhesive is heated in an oven at 200 ° C. for 3 minutes. Then, before the heat of the steel plate was cooled, a laminator was used to attach the decorative sheet, and immediately after that, it was cooled with cold water.
A: Whitening cannot be confirmed at all.
○: Almost no whitening can be confirmed, but there are some cases in which whitening is slightly caused when the number of tests is large.
Δ: Slightly whitened state can be confirmed.
X: The whitened state can be confirmed clearly.
Table 3 shows the evaluation results of [1] to [4] for the examples and comparative examples.

In Examples 1-4 which are the decorative sheets of this invention, it turned out that it has the outstanding peeling strength even after heat history.
Moreover, the decorative sheet of Example 2 was superior in peel strength after heat history to the decorative sheet of Example 1. This is because the block copolymer (c) used in Example 1 has a crystalline ethylene block only at one end of the molecular chain, whereas the block copolymer (c) used in Example 2 is used. Has a crystalline ethylene block at both ends of the molecular chain, so the block copolymer (c) and the ethylene / α-olefin copolymer resin (b) have high affinity, and the ethylene / α-olefin copolymer resin. This is considered to be because the occurrence of divergence (craze) at the island interface due to (b) and the accompanying decrease in cohesive force were suppressed.
Moreover, it turned out from the comparison with Example 2 and Example 3 that the peel strength after a heat history is excellent, so that there is much content of a block copolymer (c). This increases the compatibility of the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b) by increasing the content of the block copolymer (c), and the occurrence of dissociation (craze). This is considered to be because the decrease in cohesive force accompanying it was further suppressed.
The decorative sheet of Example 2 in which the melt flow rate of the polypropylene resin (a) is 38 times that of the ethylene / α-olefin copolymer resin (b) is 2.5 times. The peel strength was superior to that of No. 4 decorative sheet. This is because the surface area of the sea-island interface between the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b) is reduced by increasing the ratio of the melt flow rate, and the dissociation (craze) is further suppressed. It is believed that there is.

  Further, when Examples 1 to 3 are compared, the compatibility between the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b) increases depending on the type and amount of the block copolymer (c). The degree of whitening in the bending test was small. This is considered to be because whitening occurs because light is irregularly reflected at the part of the sea-island interface (craze), and the block copolymer (c) can suppress the dissociation (craze). This is considered to indicate that whitening at the time of bending is also affected.

  Moreover, the decorative sheet of Examples 1-4 was excellent also in the peeling strength after a weather resistance test.

  On the other hand, since the decorative sheet of Comparative Example 2 did not use the block copolymer (c), the peel strength was inferior compared with Examples 1-4. Further, in Comparative Example 3 in which the first transparent resin layer was formed only with the ethylene / α-olefin copolymer resin (b), the peel strength after the heat history was remarkably reduced. In Comparative Example 1 in which the first transparent resin layer was not formed, the peel strength was very low in any of the measurements [1] to [3].

  Further, in the 1R bending test, it was found from the result of Comparative Example 1 that the first transparent resin layer does not affect whitening. The decorative sheet of Comparative Example 2 has a greater degree of whitening than the decorative sheets of Examples 1 to 3, and whitening is suppressed in the order of Comparative Example 2> Example 1> Example 2> Example 3. From this, it can be considered that suppression of dissociation (crazing) by the block copolymer (c) has an influence on whitening at the time of bending.

  Moreover, the decorative sheet of Comparative Examples 1-3 was inferior in the peeling strength after a weather resistance test compared with the decorative sheet of Examples 1-4.

  Since the decorative sheet of the present invention does not use any vinyl chloride resin, there is no concern about environmental problems, and a polypropylene-based resin with a large distribution amount in the market is adopted as a main material, which is inexpensive and has high supply stability. Excellent heat resistance and weather resistance. Thereby, it is possible to provide an extremely practical decorative sheet that is excellent in design.

It is sectional drawing which showed the example of 1 embodiment of the decorative sheet of this invention. It is sectional drawing which showed other embodiment examples of the decorative sheet of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Decorative sheet 2 Decorative sheet 11 Base sheet 12 Pattern layer 13 Anchor coat layer 14 First transparent resin layer 15 Second transparent resin layer 16 Surface protective layer 17 Recessed pattern 18 Ink 19 Primer coat layer

Claims (5)

A decorative sheet in which at least an anchor coat layer and two or more transparent resin layers mainly composed of polypropylene are sequentially laminated on a base sheet,
Among the transparent resin layers, the transparent resin layer on the side in contact with the anchor coat layer is composed of polypropylene resin (a) 60 to 90 parts by mass and ethylene / α-olefin copolymer resin (b) 40 to 10 parts by mass (however, ( a total of 100 parts by mass of a) and (b)) and 1 to 40 parts by mass of a block copolymer (c) having a crystalline ethylene block.   The makeup | decoration of Claim 1 whose block copolymer (c) which has the said crystalline ethylene block is a triblock copolymer in which the crystalline ethylene block, the ethylene butylene block, and the crystalline ethylene block were connected in order. Sheet.   The makeup according to claim 1 or 2, wherein the larger value of the melt flow rate of the polypropylene resin (a) and the ethylene / α-olefin copolymer resin (b) is 3 to 70 times the smaller value. Sheet.   The decorative sheet according to any one of claims 1 to 3, wherein the two or more transparent resin layers are laminated by a heat-dissolving coextrusion laminating method using a T die.   Of the two or more transparent resin layers, 0.1 to 2.0 parts by mass of an unsaturated carboxylic acid or the anhydride is graft-polymerized on the transparent resin layer on the side in contact with the anchor coat layer. Item 5. The decorative sheet according to any one of Items 1 to 4.

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