JP7006393B2 - Decorative sheets and decorative materials - Google Patents

Description

The present invention relates to a decorative sheet used as a decorative board by adhering it to the surface of, for example, wood-based boards, inorganic boards, metal plates, etc. with an adhesive, and a decorative member using the same.

As the plastic-based decorative sheet used for decorative boards, sheets made of vinyl chloride resin, acrylic resin, polyester resin-based, olefin-based, fluororesin-based, styrene resin-based, etc. are generally used. Until around 2000, vinyl chloride resin was the most commonly used because of its workability, long-term stability, and economic efficiency.
However, vinyl chloride resin causes the generation of hydrogen chloride gas, which causes acid rain during incineration, and dioxin, which is a highly toxic substance, and also has problems such as environmental hormones due to bleeding out of the plasticizer added to the vinyl chloride resin. Therefore, it is becoming a problem from the viewpoint of environmental protection.
Against this background, from around 2000, the adoption of decorative sheets using olefin resin instead of vinyl chloride resin has rapidly expanded.

Among olefin resins, a decorative sheet using polypropylene, which has appropriate flexibility, abrasion resistance, scratch resistance, heat resistance, chemical resistance, post-processability, etc. required for a decorative sheet and is provided at a low cost. Is the most proposed, and most of them are printed on the base sheet to give a design, and the purpose is to protect the pattern and give an embossed shape of unevenness to give a feeling of design. It is manufactured by a method of laminating a transparent polypropylene resin.

However, since polypropylene resin is generally non-polar, it has poor adhesiveness to resins of the same type or different types, and when the polypropylene resin layer is laminated on another resin layer, for example, an acid functional group is introduced to bond the polypropylene resin layer. A method of laminating via a polypropylene resin and a method of providing an anchor coat layer, an adhesive layer, and the like are known (Patent Document 1).

However, it is often not possible to obtain the desired adhesion strength simply by using an acid-modified polypropylene resin, and even if it is obtained, the resin into which an acid functional group has been introduced is affected by the acid possessed by itself. There is also the problem that the weather resistance performance deteriorates over time. However, sufficient studies have not been made on what kind of material formulation can maintain sufficient adhesion strength for a long period of time.

Furthermore, in recent years, there have been many calls for further improvement in the required physical characteristics, not just for decorative sheets using resins other than vinyl chloride resin. One of the main required physical properties is to stabilize extrusion molding, and the other is to improve the post-processability of decorative sheets.

In the former stabilization of extrusion molding, the extrusion lamination method is preferably used for more efficient production, but in the case of polypropylene, the extrusion lamination alone is possible due to its low melt tension. There is a problem that it is difficult to do.

Further, in polypropylene extrusion lamination for food packaging applications, a method of applying melt tension by adding low-density polyethylene is generally used, but when this method is used for a decorative sheet, polypropylene and polyethylene are used as they are. Due to the incompatibility, an interface is generated, and fine cracks are generated through this interface during the post-processing of the decorative sheet, which causes a whitening phenomenon and impairs the design, so that there is a problem that the post-processability is poor.
As described above, studies on material formulations in consideration of both stable production of decorative sheets and post-processability have not been sufficiently conducted so far.

Japanese Patent No. 4061884

The present invention has been made to solve the above problems, and the problem thereof is to maintain the adhesive force of the transparent polypropylene resin layer for a long period of time by using an olefin-based material. Moreover, it is to provide a decorative sheet that does not cause a design change such as whitening or cracking during post-processing, with a material composition that also guarantees production stability.

The present inventor has carried out diligent research and development in order to achieve the above-mentioned problems, and as a result, has found that the problems can be solved under certain specific conditions.

That is, the invention according to claim 1 of the present invention is
In a decorative sheet in which a pattern layer and a transparent polypropylene resin layer are laminated at least in this order on a base sheet.
The transparent polypropylene resin layer has a two-layer structure of a polypropylene protective layer and a peeling stress absorbing layer in order from the surface layer side.
The peeling stress absorbing layer is (a) homopolypropylene having a tensile elasticity of 500 MPa or more, (b) random polypropylene having a tensile elasticity of 800 MPa or less, (c) a propylene / α-olefin copolymer resin having a tensile elasticity of 100 MPa or less, (d). ) Ethylene / α-olefin copolymer resin (α-olefin excludes ethylene), (e) polyethylene or homopolypropylene having a long-chain branched structure.
The melt mass flow rate (MFR) of (a) homopolypropylene and (b) random polypropylene at 230 ° C. specified by JIS K7210 is 8 or more and 50 or less, and (d) ethylene / α-olefin copolymer resin at 190 ° C. The MFR in is 2 or less,
It is a decorative sheet characterized in that two layers, a polypropylene protective layer and a peeling stress absorbing layer, are laminated by a coextrusion laminating simultaneous embossing method.

The invention according to claim 2 of the present invention for achieving the above problems is
The cosmetic according to claim 1, wherein both the (c) propylene / α-olefin copolymer resin and the (d) ethylene / α-olefin copolymer resin are polymerized using a metallocene catalyst. It is a sheet.

The invention according to claim 3 of the present invention for achieving the above problems is
When the peel stress absorbing layer is 100 parts by weight, (a) homopolypropylene occupies 10 parts by weight or more, and (d) ethylene / α-olefin copolymer resin occupies 20 parts by weight or more and 40 parts by weight or less. , The decorative sheet according to claim 1 or 2.

The invention according to claim 4 of the present invention for achieving the above problems is
The decorative sheet according to any one of claims 1 to 3, wherein a radical scavenger is added to the peel stress absorbing layer.

The invention according to claim 5 of the present invention for achieving the above problems is
The method according to any one of claims 1 to 4, wherein the acid functional group is introduced into the side surface of the pattern layer of the peeling stress absorbing layer by any method of ozone treatment, corona treatment, and plasma treatment. The decorative sheet described.

The invention according to claim 6 of the present invention for achieving the above problems is
The acid functional group introduced by any of the ozone treatment, corona treatment, and plasma treatment methods has an oxygen (O) / carbon (C) ratio in the surface treatment portion measured by X-ray photoelectron spectroscopy (ESCA). The decorative sheet according to claim 5, characterized in that it is in the range of 0.5 to 10%.

The invention according to claim 7 of the present invention for achieving the above problems is
It is a decorative member formed by using the decorative sheet according to any one of claims 1 to 6.

According to the invention according to claim 1, by forming the transparent polypropylene resin layer into two layers, that is, by forming a multilayer of a polypropylene protective layer and a peeling stress absorbing layer, durability performance such as weather resistance, chemical resistance, and scratch resistance is achieved. Then, it is possible to obtain the performance of absorbing the peeling stress while maintaining the adhesion to the adjacent pattern layer. Further, by appropriately selecting the material composition of this layer, it becomes possible to select a grade resin having a characteristic function for each.

In addition, since the transparent polypropylene resin layer is formed by the coextrusion laminating simultaneous embossing method, it contributes to the effect of suppressing the whitening phenomenon during post-processing, and the film formation, laminating, and embossing are performed at the same time. The above-mentioned problems do not occur, and it is possible to obtain a decorative sheet that is less likely to cause whitening or cracking.

According to the second aspect of the present invention, it is possible to increase the activity of the polymerization catalyst used in the manufacturing process of the elastomer component. As a result, the proportion of low molecular weight components in the produced resin can be reduced. Since the low molecular weight component has high mobility in the resin and easily precipitates from the resin, it also promotes the precipitation of the additive in the resin and causes a decrease in weather resistance. However, when a metallocene catalyst is used, it causes a decrease in weather resistance. Such problems are unlikely to occur.

According to the third aspect of the present invention, it is possible to maintain the adhesive force and suppress whitening / cracking at a high level.

According to the invention of claim 4, since the radical scavenger detoxifies the radicals generated by oxidation, the rate of resin deterioration can be suppressed. As a result, the adhesive force of the transparent polypropylene resin layer can be maintained for a long period of time.

According to the invention of claim 5 or 6, since it is not necessary to introduce an acid functional group into the peeling stress absorbing layer in advance, deterioration of the resin can be suppressed, and as a result, the adhesion of the transparent polypropylene resin layer can be maintained for a long period of time. Can be held for a long time.

The decorative member produced by using the decorative sheet according to any one of claims 1 to 6 above maintains the adhesive force of the transparent polypropylene resin layer for a long period of time, and at the same time, whitens during post-processing. It has the characteristic that it is difficult to place changes in the design such as cracks.

It is sectional drawing which shows the layer structure as one Embodiment of the decorative sheet of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the cross-sectional structure of an embodiment of the decorative sheet of the present invention.
The pattern layer 2 is laminated on the base sheet 1 for a decorative sheet made of a non-vinyl chloride material by using, for example, a gravure printing method, and the peel stress absorbing layer 4 and the polypropylene protective layer are laminated via the anchor coat layer 3. The transparent polypropylene resin layer 7 composed of two layers of 5 is laminated by the extrusion laminating simultaneous embossing method.

Further, after introducing a functional group into the surface layer of the co-extruded polypropylene protective layer 5 by corona treatment or the like, the surface layer is coated with a top coat layer 6 having performances such as a matting effect and a scratch resistance imparting effect. The decorative sheet 10 of the present invention can be obtained.

As the material of the base material sheet 1 in the present invention, there is nothing particularly specified except for the polyvinyl chloride resin, but a polypropylene-based material is preferably used in view of printability and economy. However, this is not always the case, and for example, polyethylene, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer, polystyrene, ABS, methyl polymethacrylate, methyl polyacrylate, butyl polyacrylate, and poly. There are vinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, polyamide, nylon 6, nylon 66 and the like.

Further, it is possible to add one or more of additives such as an inorganic pigment, an antioxidant, a light stabilizer, and an antiblocking agent to the resin used for the base sheet 1 in an appropriate amount. be.

In the decorative sheet of the present invention, a base sheet made of a concealed non-vinyl chloride-based material can be used for the base sheet 1. The reason for concealing is to prevent the base material such as the wood board, the inorganic board, and the metal board to be bonded from being seen from the surface of the decorative sheet.

In order to make the base material such as a wood-based board, an inorganic board, or a metal plate to be attached to the base material sheet 1 of the decorative sheet of the present invention invisible from the surface of the decorative sheet, the base material sheet 1 is used. It is desirable to impart concealing property to the base sheet 1 of the decorative sheet and its intermediate layer by means such as addition of a pigment or formation of a pigment coating layer (concealing layer). However, this does not apply if the texture of the base material is to be utilized.

As a method of forming these concealing properties (concealing layers) and the pattern layer 2 with respect to the base sheet 1, gravure printing, concave printing, flexographic printing, etc. on the front surface and / or back surface of the base sheet 1. It is common to print by a known printing method such as silk printing, electrostatic printing, and inkjet printing, but this is not always the case.
In addition, the inks used are also known, that is, colorants such as dyes or pigments, extender pigments, etc. are added to the vehicle, and plasticizers, stabilizers, waxes, greases, desiccants, hardeners, thickeners, dispersants, etc. are added. , A filler or the like may be arbitrarily added and the ink may be sufficiently kneaded with a solvent, a diluent or the like.

Further, a concealing layer, a pattern layer 2, or both are formed on an arbitrary transfer base sheet different from the decorative sheet base sheet 1 by the above-mentioned forming method or the like, and the above-mentioned thermal laminating is performed. After bonding to the base sheet 1 by a method, a dry laminating method, a wet laminating method, an extrusion laminating method, or the like, the transfer base sheet is peeled off to remove the concealing layer, the pattern layer 2, or both. A method of transferring to the base sheet 1 can also be used.

When the T-die extrusion method is used as the method for producing the base sheet 1, the synthetic resin material for forming the base sheet 1 is directly colored with a concealing colorant such as a dye or a pigment. It is also possible to give a concealing effect by extruding from the T-die in a heat-melted state to form a film of the base sheet 1.

As a method for coloring the base sheet 1 in the T-die extrusion method in this case, a dry color method, a masterbatch method, and the like are known, but the method is not particularly limited. In the dry color method, a fine powder colorant obtained by treating a pigment with a dispersion aid or a surfactant is directly mixed into an ordinary uncolored synthetic resin material for forming a film of a base sheet 1. It is a method of coloring.
On the other hand, in the masterbatch method, a masterbatch pellet in which a normal uncolored synthetic resin material for forming a film of a base sheet 1 and a high-concentration pigment are melt-kneaded and pre-dispersed is prepared in advance. This is a method of dry-blending the masterbatch pellets with an uncolored ordinary synthetic resin material for forming a film of the base sheet 1 in an extrusion hopper.

The type of pigment may be one that is usually used, but inorganic pigments such as titanium oxide, ultramarine blue, cadmium pigment, and iron oxide are particularly desirable in consideration of heat resistance and weather resistance. Further, as organic pigments, phthalocyanine pigments, quinacridone pigments and the like can be used. The ratio of the pigment to the resin and the color are appropriately determined in consideration of the degree of concealment and the design, and are not particularly limited.

As a method of applying the pattern layer 2 to the base sheet 1, in addition to the method of applying the pattern layer 2 to the surface of the base sheet 1 as described above, there is also a method of applying the pattern layer 2 to the base sheet 1 itself (inside the layer of the sheet 1). As a method of applying the substrate sheet 1 itself, a masterbatch pellet in which a high-concentration pigment is melt-kneaded into a resin having a flow characteristic different from that of the resin of the substrate sheet 1 and pre-dispersed, or wood powder, glass powder, or the like is used. The base sheet 1 is added to the above-mentioned synthetic resin material having a concealing property for forming a film, heated and melted, extruded, and formed into a film. There is also a method of forming a pattern with glass powder or the like. Of course, it can also be used in combination with these methods for forming a color hiding property or a pattern on the base sheet 1 itself.

Further, when the calendar method is used as a method for manufacturing the base sheet 1 having a concealing property, the same method, that is, the base sheet 1 is manufactured by the calendar method, and at the same time, the base sheet 1 itself is colored and concealed. It is also possible to form a concealing property and a pattern on the base sheet 1 by a method of forming a pattern or a method in which these methods are used in combination with the above-mentioned printing method, transfer method, or the like.

As the material of the pattern layer 2, vinyl acetate-based, acrylic-based, urethane-based, ester-based, polycarbonate-based, and the like are preferably used, but the material is not limited thereto. For example, acrylic type if weather resistance and hydrolysis resistance are important, vinyl acetate type if ink adhesion is important, ester type if economic efficiency is important, or a balance between these. A mixed type or the like is preferably used in consideration of the above.

When the resin is extruded and laminated on the surface layer of the base material sheet 1 provided with the pattern layer 2 on the pattern layer side, the lamination of the anchor coat layer 3 is preferably used.
If a non-chlorine-based material is used for the anchor coat layer 3, the material is not limited, but a two-component curable urethane-based resin that forms a urethane bond by the reaction between the polyol and isocyanate is preferable. Isocyanate preferably containing at least one of hexamethylene diisocyanate and isophorone diisocyanate. The gravure method (gravure printing method, gravure coating method) is preferably used as the method for forming the anchor coat layer 3, but the method is not limited to this. For example, when considering hydrolysis resistance, the use of an acrylic or polycarbonate anchor coating agent is also preferably used.

As for the material of the polypropylene protective layer 5, random polypropylene is preferable if transparency is important, and homopolypropylene is suitable if scratch resistance is important. There is also a method of achieving both performance by melt-kneading random polypropylene and homopolypropylene, or by forming multiple layers. Further, additives such as a slip agent, an antioxidant, a weather resistant agent, a cross-linking material, a cross-linking aid, a transparent nucleating agent, and a rigid nucleating agent are preferably added to the polypropylene protective layer.

According to a diligent study by the present inventor, the transparent polypropylene resin layer 7 is made into two layers, that is, the polypropylene protective layer 5 and the pattern layer 2 which are provided with performances such as weather resistance, chemical resistance, and scratch resistance. By forming the multi-layer of the peeling stress absorbing layer 4 having the effect of absorbing the peeling stress while maintaining the adhesiveness, it becomes possible to select a grade resin having a characteristic function for each.

Further, as the material composition of the peeling stress absorbing layer 4, the material composition is as follows.
(A) Homopolypropylene with a tensile elastic modulus of 500 MPa or more,
(B) Random polypropylene with a tensile modulus of 800 MPa or less,
(C) A propylene / α-olefin copolymer resin having a tensile elastic modulus of 100 MPa or less,
(D) Ethylene / α-olefin copolymer resin (α-olefin excludes ethylene),
(E) Polyethylene or homopolypropylene having a long-chain branched structure,
It shall consist of a mixture of.
Then, JIS of the above (a) homopolypropylene and (b) random polypropylene
It is desirable that the melt mass flow rate (MFR) at 230 ° C. specified by K7210 is 8 or more and 50 or less, and (d) the MFR of the ethylene / α-olefin copolymer resin at 190 ° C. is 2 or less.

As the peel stress absorption layer 4, the peel stress relaxation capacity of the transparent polypropylene resin layer 7 can be maintained for a long period of time by using a melt-kneaded resin compound shown in the present invention. This includes (a) homopolypropylene, (b) random polypropylene, and (c) propylene / α-olefin copolymer resin (excluding ethylene as α-olefin, the same applies hereinafter) having a relatively high MFR (= low melt viscosity). The mixture of the three propylene-based resins in the above is completely compatible to form a matrix, and the ethylene / α-olefin copolymer resin having a relatively low MFR (= high melt viscosity) becomes a domain, and is defined by its elastic coefficient. This is because it is possible to absorb the stress at the time of peeling due to the flexibility.

Furthermore, by observing the melt viscosity of the peel stress absorbing layer 4 shown in the present invention, the surface area between the matrix / domain is reduced due to the action of the viscosity difference, in other words, the shape of the domain becomes close to a sphere. Things will be possible. Since the matrix / domain is incompatible, when bending is performed, minute cracks are generated at this interface, which causes macroscopic whitening and causes poor appearance. In the decorative sheet of the present invention, by minimizing the amount of cracks generated, the effect of minimizing the occurrence of microcracks is exhibited.

Furthermore, (c) the modification effect of the propylene / α-olefin copolymer resin suppresses the difference in elastic modulus between the matrix and the domain, which also suppresses minute cracks at the interface and contributes to the effect of suppressing whitening. ..

(C) The modifying effect of the propylene / α-olefin copolymer resin also exerts an effect on maintaining the adhesive force of the peeling stress absorbing layer 4 for a long period of time. This is because (c) the propylene / α-olefin copolymer resin suppresses the hardening of (a) homopolypropylene and (b) random polypropylene due to the progress of crystallization over time.

If the progress of crystallization is not suppressed, the stress relaxation capacity is lowered due to the progress of hardening, and the adhesion of the transparent polypropylene resin layer 7 is gradually lowered. However, (c) the propylene / α-olefin copolymer resin is used. By adding it, the progress of hardening can be suppressed, so that the adhesion can be maintained for a long period of time.

Further, using the coextrusion laminating simultaneous embossing method as the laminating method of the transparent polypropylene resin layer 7 also contributes to the whitening suppressing effect. In another known laminating method (for example, a dry laminating method), it is necessary to heat a metal roll having an embossed uneven inverted shape to be applied and press it against the sheet to emboss the sheet after the sheet is formed. Because of the crystalline resin, crystallization progresses due to the heat at the time of embossing, and it becomes hard. As a result, the decorative sheet is prone to whitening and cracking during bending.

If an embossed uneven reversal shape is added to the cooling roll during film formation in advance and then laminated by the dry laminating method, the problem of crystallization progressing due to the heat during embossing and hardening is solved. However, the feeling of unevenness is suppressed by the nip pressure and temperature conditions during dry laminating, and the embossed shape imparted during film formation cannot be maintained.
However, in the coextrusion laminating simultaneous embossing method, since the film formation, laminating, and embossing are performed at the same time, the above problem does not occur, and a decorative sheet that is less likely to cause whitening or cracking can be obtained.

Further, both the (c) propylene / α-olefin copolymer resin and the (d) ethylene / α-olefin copolymer resin are polymerized using a metallocene catalyst.

Further, when the peel stress absorbing layer 4 is 100 parts by weight or more, (a) homopolypropylene is 10 parts by weight or more, and (d) ethylene / α-olefin copolymer resin is 20 parts by weight or more and 40 parts by weight or less. Is preferable.

Usually, in extrusion lamination, a method of making the extruded resin side wider than the adherend substrate is common in order to trim the extruded end portion thickened by neck-in.
At that time, if the amount of (a) homopolypropylene in the peeling stress absorbing layer 4 is less than 10 parts by weight, release failure on the side surface of the rubber roll occurs due to the difference in cooling capacity between the metal embossed roll and the rubber nip roll at the extruded resin end. However, if a blending amount of 10 parts by weight or more is secured, the above problem does not occur.
Further, by using (d) 20 parts by weight or more of the ethylene / α-olefin copolymer resin, sufficient peeling stress absorption capacity is exhibited. Similarly, by setting the amount to 40 parts by weight or less, the area of the interface between polypropylene and the (d) ethylene / α-olefin copolymer resin can be suppressed, and bending whitening can be suppressed.

(E) When polyethylene or homopolypropylene having a long-chain branched structure is homopolypropylene, it is compatible with the polypropylene protective layer to reduce the surface area of the incompatible interface and suppress bending whitening during post-processing. Contribute.

Further, in the extrusion laminating method, a method using a resin in which an acid functional group is introduced in advance on the laminated surface side with the base material (for example, Mitsui Chemicals'Admer (trade name) or Mitsubishi Chemical's Modic (trade name)) is used. Although it has been used conventionally, it is not preferable from the viewpoint of maintaining adhesion for a long period of time because the acid functional group itself causes deterioration of the resin.
On the other hand, when surface treatment such as ozone treatment, corona treatment, and plasma treatment is used as in the present invention, the acid functional group is introduced only at the laminated interface, so that the absolute amount of acid can be greatly reduced. Therefore, the adhesion of the transparent polypropylene resin layer can be maintained for a long period of time.

The amount of oxygen introduced into the resin surface layer by surface treatment such as ozone treatment, corona treatment, and plasma treatment is the oxygen (O) / carbon (C) ratio specified by X-ray photoelectron spectroscopy (ESCA). The range of 0.5 to 10% is preferable.
When 0.5% or more of oxygen is introduced, sufficient adhesion strength is developed, and by setting it to 10% or less, deterioration of the peeling stress absorbing layer over time can be suppressed, and adhesion of the polypropylene resin layer over a long period of time can be suppressed. It leads to the maintenance of performance.

The top coat layer 6 is generally laminated by a gravure coating method, but various known lamination methods are used. In order to impart multiple performances at the same time, topcoat resins with different effects may be layered on top of each other, and in order to further improve performance such as scratches, they have the same effect (in this case, scratch resistance suppressing effect). The top coat resin may be laminated multiple times. Further, additives such as a matting agent, a scratch resistant agent, and a weather resistant agent may be appropriately added.

The performance superiority of the decorative sheet provided by the present invention will be further clarified from the following Examples and Comparative Examples.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to the following examples.

First, as the base sheet 1, 6% by weight of an inorganic pigment, 0.2% by weight of a phenol-based antioxidant, 0.3% by weight of a hindered amine-based photostabilizer, and 0.2% by weight of a blocking inhibitor are added to a random polypropylene resin. % The added resin was melt-extruded to a thickness of 60 μm using a T-die extruder to prepare a sheet.

After corona treatment was applied to the sheet surface, 5 parts by weight of LPNYB (isocyanate curing agent) was added to 100 parts by weight of a pattern ink (manufactured by Toyo Ink Co., Ltd .: V351 (main agent)) by a gravure printing method. After that, a wood grain pattern was applied using a methyl ethyl ketone solvent (diluted to a viscosity suitable for gravure printing) to form a pattern layer 2.

Further, after adding a two-component curing type urethane anchor coating agent (manufactured by Mitsui Chemicals Polyurethane Co., Ltd .; 100 parts by weight of Takelac A3210 (main agent) and 25 parts by weight of Takenate (isocyanate curing agent) on the wood grain pattern layer, Diluted with an ethyl acetate solvent to a viscosity suitable for gravure printing) was applied by a gravure printing method to a thickness of about 1 μm to form an anchor coat layer 3.

A resin for the peel stress absorbing layer 4 is prepared using the materials prepared based on the compounding table shown in Table 1 below, and a random polypropylene resin (prime) having an elastic modulus of 680 MPa and an MFR: 20 is further used as the polypropylene protective layer 5. For 99 parts by weight of polymer Y-2045GP, 0.5 parts by weight of benzotriazole-based ultraviolet absorber: chinubin 329 (manufactured by BASF Japan) as a weather resistant agent, and hindered amine-based radical trapping agent: Kimasorb 2020 (manufactured by BASF Japan). Was melt-mixed at a ratio of 0.5 parts by weight to prepare pellets.

Subsequently, using two extruders and a feed block type T-die, extrusion laminating was performed at an extrusion temperature of 230 ° C. by a coextrusion laminating method, and at the same time, an uneven inverted shape of wood grain embossing was imparted to the roll surface. Wood grain embossing was added to the surface layer using a cooling roll (the maximum height difference of the cooling roll embossing was 37 μm).
For the T-die, the opening width (lip gap) of the resin discharge portion was set to 2.0 mm, and the distance (air gap) from the discharge portion of the T-die to the laminated nip portion was set to 110 mm. The coextrusion thickness was 10 μm for the stress absorbing layer 4 and 50 μm for the polypropylene protective layer 5, for a total of 60 μm, and coextrusion laminating was performed so that the anchor coat layer 3 and the stress absorbing layer 4 were in contact with each other.

Further, at the time of laminating, an acid functional group was imparted to the laminating interface by ozone treatment. The ozone treatment amount was adjusted so that the ozone concentration from the ozone generator was changed and the O / C ratio in the ESCA analysis of the stress absorbing layer was within the range of 1 to 3%. For the ESCA analysis sample, a fluorine sheet was used instead of the base material coated with the anchor coating agent to suppress contamination of the laminated interface and to improve the analysis accuracy.

After further corona-treating the surface layer, 6 parts by weight of benzotriazole-based ultraviolet absorber: Chinubin 329 (manufactured by BASF Japan) as a weathering agent was added to the surface of 92 parts by weight of the acrylic topcoat agent in terms of solid content. , Hinderdamine-based radical scavenger: Tinubin 249 (manufactured by BASF Japan) added in a proportion of 2 parts by weight, diluted with ethyl acetate so as to be suitable for gravure coating, and then applied using a gravure printing method in an amount of 2 g / Three coats were applied at m ² . In this way, the decorative sheets of Examples 1 to 11 were obtained.

In the formulation of Example 7 in Table 1, a sample in which the ozone concentration was changed was prepared, and the O / C ratio in the ESCA analysis of the peel stress absorbing layer was within the range of 0.4 to 11.1%. Prepared samples were prepared.

(Comparative example)
The decorative sheets of Comparative Examples 1 to 7 were prepared by the same method as in Examples except that the resin for the peel stress absorbing layer was prepared using the materials prepared based on the compounding table at the ratio shown in Table 2 below. Got For reference, the O / C ratio in the ESCA analysis of the peel stress absorbing layer is also added in Table 2.

The performance comparison evaluations performed on the samples of the examples and comparative examples prepared above are shown below.

[Performance comparison 1: Weather resistance evaluation (adhesion evaluation of polypropylene resin layer over a long period of time)]
The prepared decorative sheet was attached to a wood substrate using an emulsion adhesive BA-10L (manufactured by Japan Coated Resin), and then the weather resistance performance was evaluated with a sunshine weather meter weather resistance tester.
The test conditions were a black panel temperature of 63 ° C. and a rainfall cycle of the first 18 minutes of 120 minute irradiation. After performing a weather resistance test for 2000 hours, make a 1-inch wide notch and peel off at the interface between the base sheet 1 and the peeling stress absorbing layer 4 using a cutter, solvent, etc. (The pattern layer 2 and the anchor coat layer 3 are peeled off. The peeling strength value (unit: N / inch) was measured by conducting a peeling test at a peeling speed of 50 mm / min and a peeling accuracy of 180 °.
The peel strength value may be 20 N / inch or more.

[Performance comparison 2: Post-workability evaluation]
After laminating the created decorative sheet on a hot-dip galvanized steel plate substrate with a thickness of 0.5 mm, it is bent by 0R (inner angle radius as much as possible) under the respective environments of outside temperature 25 ° C, 15 ° C, and 5 ° C. Bending to the minimum) was performed, and whitening and cracking of the bent portion were evaluated.
A urethane modified polyester polyol / polyisocyanate adhesive was used as the adhesive, and the adhesive was applied using a bar coater so that the coating thickness after drying was 5 g / m ² . For bonding to a steel sheet base material, the adhesive-coated steel sheet is heated at 200 ° C. for 3 minutes to activate the adhesive, and the decorative sheet prepared in Examples and Comparative Examples is used as the basis of the decorative sheet. The material sheet 1 side was bonded so as to be on the adhesive surface side, crimped with a rubber roll, and then rapidly cooled in a water tank.

The evaluation criteria were as follows.
◯: No change is seen in the bent portion, and there are no defects such as cracks.
Δ: A part of the bent portion was slightly whitened or slightly cracked.
X: Clear whitening was observed in the bent portion, or clear cracking occurred.

[Performance comparison 3: Productivity evaluation]
In the coextrusion lamination, the line speed and the screw rotation speed were changed without changing the extrusion thickness, and the production speed at which stable production was possible was confirmed.
As this evaluation standard, the upper limit of the line speed at which stable laminating was possible, that is, the upper limit of the state where there was no problem in "taken" and "rollability" was taken. Here, "taken" means that the end portion of the extruded resin (thickened by neck-in) is wound (taken) around the laminated nip roll side. Further, "rollability" means that when the resin discharged from the T-die is stretched in the flow direction in a molten state, the resin cannot follow the change and the thickness becomes uneven.

Table 3 below shows the evaluation results of the decorative sheets of Examples and Comparative Examples.

As can be seen from the evaluation results in Table 3, the decorative sheets of Examples are compatible with each other at a high level of performance comparisons 1 to 3, and according to the decorative sheet of the present invention, weather resistance, post-workability, and productivity are achieved. It was found that excellent performance can be obtained in terms of sex.
On the other hand, in the decorative sheet of the comparative example, any one or more items are inferior to the decorative sheet of the example. That is, Comparative Examples 1, 2 and 6 had poor post-workability in Performance Comparison 2, and Comparative Examples 1 to 5 and 7 were inferior in productivity in Performance Comparison 3. Further, Comparative Examples 1, 6 and 7 were also inferior in the weather resistance of Performance Comparison 1.

Since the decorative sheet of the present invention does not use vinyl chloride at all, there is no concern about environmental problems, and the adhesion between the polypropylene protective layer and the pattern layer does not decrease even with stress such as heating and ultraviolet irradiation. Further, it is possible to provide a decorative sheet without deterioration of design such as whitening even when the decorative sheet of the present invention is bonded to various base materials and bent. There is no problem with production stability during production.

1 ... Base sheet 2 ... Pattern layer 3 ... Anchor coat layer 4 ... Peeling stress absorption layer 5 ... Polypropylene protective layer 6 ... Top coat layer 7 ... Transparent polypropylene resin layer 10 ... Cosmetic sheet

Claims (7)

In a decorative sheet in which a pattern layer and a transparent polypropylene resin layer are laminated at least in this order on a base sheet.
The transparent polypropylene resin layer has a two-layer structure of a polypropylene protective layer and a peeling stress absorbing layer in order from the surface layer side.
The peeling stress absorbing layer is (a) homopolypropylene having a tensile elasticity of 500 MPa or more, (b) random polypropylene having a tensile elasticity of 800 MPa or less, (c) a propylene / α-olefin copolymer resin having a tensile elasticity of 100 MPa or less, (d). ) Ethylene / α-olefin copolymer resin (α-olefin excludes ethylene), (e) polyethylene or homopolypropylene having a long-chain branched structure.
The melt mass flow rate (MFR) of (a) homopolypropylene and (b) random polypropylene at 230 ° C. specified by JIS K7210 is 8 or more and 50 or less, and (d) ethylene / α-olefin copolymer resin at 190 ° C. The MFR in is 2 or less,
A decorative sheet characterized in that two layers, a polypropylene protective layer and a peeling stress absorbing layer, are laminated by a coextrusion laminating simultaneous embossing method. The cosmetic according to claim 1, wherein both the (c) propylene / α-olefin copolymer resin and the (d) ethylene / α-olefin copolymer resin are polymerized using a metallocene catalyst. Sheet. When the peel stress absorbing layer is 100 parts by weight, (a) homopolypropylene occupies 10 parts by weight or more, and (d) ethylene / α-olefin copolymer resin occupies 20 parts by weight or more and 40 parts by weight or less. , The decorative sheet according to claim 1 or 2. The decorative sheet according to any one of claims 1 to 3, wherein a radical scavenger is added to the peel stress absorbing layer. The method according to any one of claims 1 to 4, wherein the acid functional group is introduced into the side surface of the pattern layer of the peeling stress absorbing layer by any method of ozone treatment, corona treatment, and plasma treatment. The described cosmetic sheet. The acid functional group introduced by any of the ozone treatment, corona treatment, and plasma treatment methods has an oxygen (O) / carbon (C) ratio in the surface treatment portion measured by X-ray photoelectron spectroscopy (ESCA). The decorative sheet according to claim 5, characterized in that it is in the range of 0.5 to 10%. A decorative member formed by using the decorative sheet according to any one of claims 1 to 6.

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