JP7743725B2 - Decorative sheet - Google Patents

Description

The present invention relates to a decorative sheet that is attached to an item to decorate the item.

Decorative sheets have been used for decorating the surfaces of furniture, fixtures, etc. In recent years, there has been an increasing demand for decorative sheets (wrapping sheets) with patterns for decorating the exterior of automobiles.
In a decorative sheet having a design, a printed layer corresponding to the pattern of the design is partially formed on a base layer, and the design of this printed layer is imparted to the sheet.
Patent Documents 1 to 3 disclose decorative sheets in which a printed layer is partially formed on a substrate layer.

WO 2007/116942 Japanese Patent Application Publication No. 3-224736 Japanese Patent Application Laid-Open No. 2006-239926

To improve durability, decorative sheets with printed designs must have a transparent resin layer laminated on the surface side (the side where the printed layer is provided). However, because the printed layer on which the design is printed is provided only partially, the thickness of the printed layer portion can cause the following problems:

In order to improve the design, it is basically desirable that the printed layer be thick. However, if the printed layer is too thick, the step at the boundary between the part where the printed layer is provided and the other part becomes large. The transparent resin layer is provided on the base layer on which the printed layer is provided by thermal lamination, but during this process, voids are generated at the edge of the printed layer where the step of the printed layer occurs, and there is a concern that this will result in a decrease in adhesion.
On the other hand, if the printing layer is made too thin in order to prevent the occurrence of the voids, there is a concern that the hiding power of the base may be insufficient, or the depth of the color or pearl may be insufficient, resulting in a decrease in design.

Another possible solution to the above problem is to provide an adhesive or pressure-sensitive adhesive layer between the substrate layer and the transparent resin layer to fill in the gaps. However, this would complicate the manufacturing process and increase the amount of material required, resulting in higher costs and a new problem: the transparent resin layer's ability to conform to deformations in the substrate would be reduced. It would also be necessary to consider the environmental resistance of the adhesive or pressure-sensitive adhesive layer.

The objective of the present invention is to provide a decorative sheet that has a simple structure, can be manufactured inexpensively, has a high level of designability, and exhibits good adhesion between the transparent resin layer and the substrate layer.

The present invention solves the above-mentioned problems by the following solutions. For ease of understanding, the following explanation uses reference numerals corresponding to the embodiments of the present invention, but the present invention is not limited to these.

The first invention is a decorative sheet (1) comprising a base layer (10), a partially printed printed layer (20) disposed on top of the base layer (10), and a transparent resin layer (30) laminated to the base layer (10) with the printed layer (20) sandwiched between them, wherein the printed layer (20) has a thickness of 3 μm or more and 12 μm or less, and at least a portion of the printed layer (20) is embedded in the base layer (10), and the storage modulus of the base layer (10) at 165°C is smaller than the storage modulus of the transparent resin layer (30) at 165°C.

The second invention is the decorative sheet (1) described in the first invention, wherein the storage modulus of the base layer (10) at 165°C is 1.5 MPa or less.

The third invention is the decorative sheet (1) according to the first or second invention, wherein the base layer (10) contains 31 to 45 parts by mass of a polyester plasticizer per 100 parts by mass of vinyl chloride resin.

The fourth invention is the decorative sheet (1) according to any one of the first to third inventions, wherein the transparent resin layer (30) contains an acrylic resin and the printing layer (20) contains an acrylic resin.

The fifth invention is a decorative sheet (1) according to any one of the first to fourth inventions, in which the printed layer (20) is entirely embedded within the base layer (10).

The sixth invention is a decorative sheet (1) according to any one of the first to fifth inventions, which is used for the body of an automobile.

The seventh invention is a method for manufacturing a decorative sheet according to any one of the first to sixth inventions, comprising the steps of forming the printing layer (20) on the base layer (10) or the transparent resin layer (30), and thermally laminating the transparent resin layer (30) to the base layer (10) at a temperature of 150°C or higher and 170°C or lower, with the printing layer (20) sandwiched between them.

The present invention provides a decorative sheet that has a simple structure, can be manufactured inexpensively, has a high level of designability, and exhibits good adhesion between the transparent resin layer and the substrate layer.

1 is a cross-sectional view showing an embodiment of a decorative sheet 1 according to the present invention. 3A to 3C are diagrams illustrating a manufacturing method of the decorative sheet 1. FIG. 10 is a cross-sectional view of a decorative sheet 100 in which the printed layer 20 is not embedded in the base layer 10 side. FIG. 10 is a diagram showing the results of comparative evaluation. FIG. 2 is a micrograph showing a cross section of the decorative sheet 1. 1 is a cross-sectional view showing an embodiment of a decorative sheet 2 according to the present invention.

The best mode for implementing the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a cross-sectional view showing an embodiment of a decorative sheet 1 according to the present invention.
Note that the figures shown below, including FIG. 1, are schematic diagrams, and the size and shape of each part are exaggerated or omitted as appropriate to facilitate understanding.
In the following description, specific numerical values, shapes, materials, etc. are given, but these can be changed as appropriate.
It should be noted that the specific numerical values specified in the present specification and claims should be treated as including a general margin of error. In other words, a difference of about ±10% is not substantially different, and values set within a range slightly exceeding the numerical range of the present invention should be interpreted as being substantially within the scope of the present invention.

The decorative sheet 1 of this embodiment can impart excellent design and weather resistance to an adherend, particularly one having a three-dimensional curved surface. This decorative sheet is suitable for use on automobile bodies, but is not limited thereto. It can also be used for interior or exterior (exterior) covering materials for vehicles such as railway cars, ships, and airplanes, panel materials for various signs and outdoor advertisements, wall materials (exterior materials, interior materials) for buildings, fittings such as partitions, doors, and window frames, desks, dining tables, cupboards, counter tables, sinks, furniture, interior decorations, and the like.
The decorative sheet 1 of this embodiment includes a base layer 10, a printing layer 20, a transparent resin layer 30, and an adhesive layer 40. The decorative sheet 1 of this embodiment is a hand-applied decorative sheet that is manually attached to an object.

<Base material layer>
The storage modulus of the base material layer 10 at 165°C is smaller than the storage modulus of the transparent resin layer 30 at 165°C. This makes the base material layer 10 more easily deformable than the transparent resin layer 30 during thermal lamination, which will be described later. By performing thermal lamination in this state, the printing layer 20 is embedded into the base material layer 10. The base material layer 10 is not limited to being colorless and transparent, and may contain a colorant.

The storage modulus (E') of the base material layer 10 at 165°C, as measured by dynamic viscoelasticity measurement at a frequency of 10 Hz and a temperature of 165°C, is preferably 0.2 MPa or more and 1.5 MPa or less. A storage modulus of 0.2 MPa or more tends to result in the base material layer 10 being not too soft and providing sufficient strength, while a storage modulus of 1.5 MPa or less tends to result in the base material layer 10 being not too hard and providing sufficient embedding of the printing layer 20. Note that, in this specification, the storage modulus at 165°C is a value measured in accordance with JIS K 7244-4:1999 using a dynamic modulus measuring device (DVA-225 manufactured by IT Measurement & Control Co., Ltd.) at a frequency of 10 Hz, a temperature of 165°C, a heating rate of 5°C/min, a sample width of 5 mm, a chuck distance of 10 mm, an upper limit elongation of 200%, and a minimum load of 1 mN. The same value is obtained before and after lamination or thermal lamination.

The storage modulus of the base layer 10 can be adjusted to fall within the above range by, for example, optimizing the type and amount of plasticizer in the vinyl chloride resin, changing the type of resin, or optimizing the density and molecular weight of the resin. In this embodiment, the base layer 10 used contains 100 parts by weight of 150 μm polyvinyl chloride and 31 parts by weight, 39 parts by weight, or 45 parts by weight of polyester plasticizer.

Vinyl chloride resins are primarily polyvinyl chloride (PVC), obtained by polymerizing vinyl chloride monomer. However, the following copolymers, obtained by copolymerizing vinyl chloride monomer with other monomers, can also be used. Monomers copolymerizable with vinyl chloride monomer include vinyl esters such as vinyl acetate and vinyl propionate; acrylic esters such as methyl acrylate and butyl acrylate; methacrylic esters such as methyl methacrylate and ethyl methacrylate; maleic esters such as butyl maleate and diethyl maleate; fumaric esters such as dibutyl fumarate and diethyl fumarate; vinyl ethers such as vinyl methyl ether, vinyl butyl ether, and vinyl octyl ether; vinyl cyanides such as acrylonitrile and methacrylonitrile; olefins such as ethylene, propylene, butylene, and styrene; dienes such as isoprene and butadiene; vinylidene halides other than vinyl chloride, such as vinylidene chloride and vinyl bromide; and allyl phthalates such as diallyl phthalate. These monomers may be used alone or in combination of two or more.

Vinyl chloride resins can also be used as graft copolymers in which vinyl chloride monomers are grafted onto the following polymers. Examples of polymers to which vinyl chloride monomers are grafted include ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide copolymer, ethylene-ethyl acrylate copolymer, ethylene-ethyl acrylate-carbon monoxide copolymer, ethylene-methyl methacrylate copolymer, and ethylene-propylene copolymer.

The average degree of polymerization of vinyl chloride resins is preferably 500 to 4000, more preferably 700 to 3900, and even more preferably 1000 to 3800. When the average degree of polymerization is within the above range, excellent mechanical strength and moldability are obtained. The average degree of polymerization is measured in accordance with JIS K6721.

A plasticizer is added to the vinyl chloride resin used as the base layer 10 to enhance the embeddability of the printing layer 20, thereby adjusting the storage modulus, hardness, elastic modulus, etc. The plasticizer is not particularly limited as long as it is compatible with the vinyl chloride resin. Examples include phthalate-based plasticizers such as dibutyl phthalate (DBP), dioctyl phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), and diundecyl phthalate (DUP); adipate-based plasticizers such as dibutyl adipate; phosphate-based plasticizers such as tributyl phosphate, tricresyl phosphate, and triphenyl phosphate; trimellitic acid-based plasticizers such as tributyl trimellitate and trioctyl trimellitate; various known polyester-based plasticizers such as adipate-based polyesters; and citric acid esters such as acetyl tributyl citrate and acetyl trioctyl citrate. Among these, polyester-based plasticizers are preferred. These plasticizers may be used alone or in combination of two or more.

Adipic acid-based polyester plasticizers with a weight-average molecular weight of 1,000 to 3,000 are preferably used. Adipic acid-based polyester plasticizers are the reaction product of adipic acid and a dihydric alcohol, such as ethylene glycol, propylene glycol, butanediol, and 1,6-hexanediol. These dihydric alcohols may be used alone or in combination of two or more. Specific examples of adipic acid-based polyester plasticizers include poly(propylene glycol, adipic acid) esters, poly(butanediol, adipic acid) esters, poly(ethylene glycol, adipic acid) esters, poly(1,6-hexanediol, butanediol, adipic acid) esters, poly(butanediol, ethylene glycol, adipic acid) esters, and poly(ethylene glycol, propylene glycol, butanediol, adipic acid) esters. By using a polymeric adipic acid polyester plasticizer with a weight-average molecular weight of 1,000 or more and 3,000 or less, the embedding properties of the printing layer 20 can be exhibited and bleeding out can be suppressed.

The plasticizer content is preferably 31 to 45 parts by weight, more preferably 34 to 40 parts by weight, and particularly preferably 37 to 39 parts by weight, per 100 parts by weight of vinyl chloride resin. Setting the plasticizer content to 31 parts by weight or more makes the vinyl chloride resin flexible, allowing the printing layer 20 to be embedded. On the other hand, setting it to 45 parts by weight or less maintains the strength of the base layer 10 and suppresses bleeding out of the plasticizer.

Examples of resins other than vinyl chloride resins that can be used for the base layer 10 include thermoplastic polyurethane (TPU), PVA, EVA, etc.

The thickness of the base layer 10 is preferably 80 to 180 μm. Having a thickness of 80 to 180 μm is advantageous in terms of bending processability during wrapping and other processes. The base layer 10 may also be colored.

<Print layer>
The printing layer 20 is a pattern layer on which the pattern (design) of the decorative sheet 1 is formed. Examples of binder resins constituting the printing layer 20 include acrylic resins, vinyl chloride-vinyl acetate copolymer resins, and acrylic (vinyl chloride-vinyl acetate copolymer) resins. Among these, from the viewpoint of embeddability in the base layer 10, it is preferable to include an acrylic resin having a higher storage modulus and hardness than the base layer 10. Note that in this case, the base layer 10 is adjusted to be soft, thereby enabling the printing layer 20 to be embedded in the base layer 10, and therefore there is no need to include a photocurable component in the printing layer as in Patent Document 1. This allows for the use of a normal printing layer, and the photocuring process is not required.

As described above, adjusting the base layer 10 to be soft allows the printing layer 20 to be embedded in the base layer 10. Therefore, the storage modulus of the printing layer 20 at 165°C is not particularly limited, but it is preferably greater than the storage modulus of the base layer 10 at 165°C. Furthermore, the storage modulus of the printing layer 20 at 165°C is preferably 2 MPa or more and 15 MPa or less. If it is 2 MPa or more, the printing layer 20 will be more likely to be embedded in the base layer 10, and if it is 15 MPa or less, cracking of the printing layer 20 during wrapping will be more likely to be prevented.

The storage modulus of the printing layer 20 at 165°C can be adjusted, for example, by adjusting the molecular weight of the binder resin or, if multiple binder resins are used, by adjusting their blending ratio.

Various color pigments, color dyes, etc. are added to the printed layer 20. The printed layer 20 can be formed by, for example, screen printing, gravure printing, etc. In this embodiment, the printed layer 20 is partially formed on the substrate layer 10 by applying a printing ink containing a mixed resin of vinyl chloride-vinyl acetate copolymer and acrylic resin as a binder using a gravure printing method. The printed layer 20 has a thickness of 3 μm or more and 12 μm or less. It is also desirable that the thickness of the printed layer 20 be 6 μm or more. In this specification, the thickness of the printed layer refers to the maximum value measured at 20 random locations.

The thickness of the printed layer embedded in the base material layer 10 is, for example, 1 to 10 μm.
The thickness of the printed layer present in the transparent resin layer 30 is preferably 3 μm or less, and more preferably 2 μm or less. Within this range, the effects of the present invention can be more effectively obtained.

<Transparent resin layer>
The transparent resin layer 30 is a transparent resin layer laminated on the base layer 10 with the printed layer 20 sandwiched therebetween, and is provided to protect the printed layer 20 .

The transparent resin layer 30 is required to have a higher storage modulus and hardness than the above-mentioned base layer 10, which allows the printing layer 20 to be embedded in the base layer 10. From this perspective, the transparent resin layer 30 preferably contains an acrylic resin. The thickness of the transparent resin layer 30 is preferably 30 μm or more and 100 μm or less, and more preferably 40 μm or more and 90 μm or less.

There are no particular restrictions on the acrylic resin, so long as it can be formed into a film or sheet by the calendaring method, and any known acrylic resin can be appropriately selected and used. Specific examples include polymers or copolymers of methacrylic acid or methacrylic acid esters, such as polymethyl (meth)acrylate (PMMA), and copolymers of alkyl methacrylate, alkyl acrylate, and styrene.

The transparent resin layer 30 may have a two-layer structure consisting of an acrylic resin layer located on the substrate layer side and a fluororesin-containing layer located on the surface side. Fluororesin refers to a polymer containing a fluorine-containing monomer as a polymerized component. Examples of fluororesin include resins containing a polymerized component selected from tetrafluoroethylene, trifluorochloroethylene, vinyl fluoride, and vinylidene fluoride. More specific examples of fluororesin in the present invention include homopolymers of fluorine-containing polymerized components such as tetrafluoroethylene resin, vinyl fluoride resin, and vinylidene fluoride resin, as well as copolymers containing the above polymerized components, such as trifluorochloroethylene-vinylidene fluoride copolymer, vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer. The thickness of the fluororesin-containing layer 16 is preferably 3 μm to 20 μm, more preferably 5 μm to 15 μm.

The transparent resin layer 30 in this embodiment can be, for example, a commercially available laminate in which an acrylic resin layer and a fluororesin layer are co-extruded. Examples of such laminate films that can be used include Acryplene FBS006 manufactured by Mitsubishi Chemical Corporation, FT-50Y manufactured by Kureha Corporation, and DX Film manufactured by Denka Company, Limited.

The storage modulus of the transparent resin layer 30 at 165°C is greater than the storage modulus of the substrate layer 10 at 165°C. This allows the printing layer 20 to be embedded within the substrate layer 10. Specifically, the storage modulus (E') measured by dynamic viscoelasticity measurement at a frequency of 10 Hz and a temperature of 165°C is preferably 4 MPa or greater and 15 MPa or less. If it is 4 MPa or greater, the transparent resin layer 30 is not too soft, and the printing layer 20 tends to be sufficiently embedded in the substrate layer 10. If it is 15 MPa or less, the processability and shape conformability during thermal lamination tend to be good. The storage modulus can be measured using a conventionally known dynamic modulus analyzer (DMA).

The storage modulus of the transparent resin layer 30 can be adjusted to fall within the above range, for example, by changing the type of resin or optimizing the density or molecular weight of the resin.

<Adhesive layer>
The adhesive layer 40 is a layer of adhesive for attaching the decorative sheet 1 to an article. There are no particular limitations on the adhesive used for the adhesive layer 40, but examples of adhesives that can be used include rubber-based, acrylic-based, olefin-based, polyester-based, and polyurethane-based adhesives. If necessary, a separator may be provided that is temporarily bonded to and covers the adhesive layer 40.

Next, a method for manufacturing the decorative sheet 1 will be described.
FIG. 2 is a diagram illustrating a method for manufacturing the decorative sheet 1. As shown in FIG.
First, the print layer 20 is printed on one surface (the upper surface in FIG. 2) of the base material layer 10, and then dried (FIG. 2(a)).

Next, a transparent resin sheet that will become the transparent resin layer 30 is placed on the side on which the printing layer 20 is provided (Figure 2(b)), and the substrate layer 10 and the transparent resin layer 30 are thermally laminated by passing them between pressure rollers (not shown) heated to a temperature of 150°C or higher and 170°C or lower.
Here, the storage modulus of the base material layer 10 in this embodiment at 165°C is 1.1 MPa. The storage modulus of the transparent resin layer 30 at 165°C is 4.7 MPa. That is, the storage modulus of the base material layer 10 at 165°C is smaller than the storage modulus of the transparent resin layer 30 at 165°C. Therefore, when thermally laminated, the base material layer 10 is more easily deformed than the transparent resin layer 30. By performing thermal lamination in this state, the printing layer 20 is embedded in the base material layer 10.
By setting the thermal lamination temperature to 150°C or higher, the laminate strength is increased, and the transparent resin layer 30 is less likely to peel off from the base layer 10 when the decorative sheet 1 is attached to an object while being stretched. Furthermore, by setting the thermal lamination temperature to 170°C or lower, the base layer 10 can be made more easily deformable than the transparent resin layer 30, so the printing layer 20 can be embedded in the base layer 10 side.

FIG. 3 is a cross-sectional view of the decorative sheet 100 in which the printed layer 20 is not embedded in the base layer 10 side.
3, in the decorative sheet 100, the printing layer 20 is not embedded into the base layer 10. In this state, the protrusion of the printing layer 20 creates a large step, which can result in thermal lamination with voids 21 remaining near the edges of the printing layer 20. If voids 21 remain, this can result in a decrease in adhesion.
In contrast, in the decorative sheet 1 of this embodiment, at least a portion of the printing layer 20 is embedded in the base layer 10, thereby reducing the amount of protrusion of the printing layer 20 toward the transparent resin layer 30, and as a result, no voids remain after thermal lamination. The amount of embedment of the printing layer 20 in the base layer 10 varies depending on the storage modulus of the base layer 10 and the transparent resin layer 30, but it is desirable for 40% or more of the thickness of the printing layer 20 to be embedded in the base layer 10 to prevent the generation of voids. Alternatively, the entire printing layer 20 may be embedded in the base layer 10, as in the decorative sheet 2 shown in FIG. 6 .

Next, the present invention will be explained in more detail by showing several examples and comparative examples. However, the present invention is not limited to the following examples in any way.

Example 1
A vinyl chloride resin (storage modulus at 165°C: 1.1 MPa) containing a plasticizer and having a thickness of 150 μm was used as the base layer 10. The plasticizer was a polyester plasticizer added in an amount of 39 parts by mass per 100 parts by mass of the vinyl chloride resin. One surface of this base layer 10 was subjected to gravure printing using a printing ink (storage modulus at 165°C: 3.0 MPa) containing a mixed resin of vinyl chloride-vinyl acetate copolymer and acrylic resin as a binder, to form a printed layer 20.
A 50 μm thick transparent resin layer 30 (FBS007 manufactured by Mitsubishi Chemical Corporation, storage modulus at 165° C.: 4.7 MPa), which was formed by co-extrusion of a 45 μm acrylic resin layer and a 5 μm fluororesin layer, was heat-laminated onto the surface of the printed layer 20 at a set temperature of 165° C. A metal roll was used, and the sheet was pressed at 2.5 t against a sheet width of 1300 mm to heat-laminate the acrylic resin layer side and the printed layer 20 side.
The thickness of the printed layer 20 of the prepared decorative sheet was 12 μm.

Example 2
A decorative sheet having a printing layer 20 of 6 μm in thickness was produced using the same materials and conditions as in Example 1, except that the thickness of the printing ink in the gravure printing was changed.

Example 3
A decorative sheet having a printing layer 20 of 3 μm in thickness was produced using the same materials and conditions as in Example 1, except that the thickness of the printing ink in the gravure printing was changed.

Example 4
A decorative sheet was produced using the same materials and conditions as in Example 2, except that a 150 μm thick vinyl chloride resin (storage modulus at 165°C: 1.4 MPa) containing 31 parts by mass of polyester plasticizer added to 100 parts by mass of vinyl chloride resin was used as the base layer 10.

Example 5
A decorative sheet was produced using the same materials and conditions as in Example 2, except that a 150 μm thick vinyl chloride resin (storage modulus at 165°C: 0.8 MPa) containing 45 parts by mass of polyester plasticizer added to 100 parts by mass of vinyl chloride resin was used as the base layer 10.

Example 6
A decorative sheet was produced using the same materials and conditions as in Example 5, except that a 50 μm transparent resin layer 30 of acrylic resin (HBS006H manufactured by Mitsubishi Chemical Corporation, storage modulus at 165° C.: 1.0 MPa) was used.

(Comparative Example 1)
A decorative sheet having a printing layer 20 of 15 μm thickness was produced using the same materials and conditions as in Example 1, except that the thickness of the printing ink in the gravure printing was changed.

(Comparative Example 2)
A decorative sheet having a printing layer 20 of 2 μm thickness was produced using the same materials and conditions as in Example 1, except that the thickness of the printing ink in the gravure printing was changed.

(Comparative Example 3)
A decorative sheet was produced using the same materials and conditions as in Example 2, except that PET (storage modulus at 165° C.: 590 MPa) having a thickness of 100 μm was used as the base layer 10 .

(Comparative Example 4)
A decorative sheet was produced using the same materials and conditions as in Example 2, except that a 120 μm thick vinyl chloride resin (storage modulus at 165°C: 2.0 MPa) in which 28 parts by mass of polyester plasticizer was added to 100 parts by mass of vinyl chloride resin was used as the base layer 10, and a 50 μm thick transparent resin layer 30 (DX-14S0250, manufactured by Denka Company Ltd., storage modulus at 165°C: 1.3 MPa) in which an acrylic resin layer and a fluororesin layer were laminated by co-extrusion was used.

(Comparative Example 5)
A decorative sheet was produced using the same materials and conditions as in Example 2, except that a 120 μm thick vinyl chloride resin (storage modulus at 165°C: 2.0 MPa) was used as the base layer 10, in which 28 parts by mass of polyester plasticizer was added to 100 parts by mass of vinyl chloride resin, and a 50 μm thick acrylic resin transparent resin layer 30 (HBS006H, manufactured by Mitsubishi Chemical Corporation, storage modulus at 165°C: 1.0 MPa) was used.

FIG. 4 is a diagram showing the results of the comparative evaluation.
In the column for evaluating the base hiding ability in Figure 4, ◯ indicates that the base was sufficiently hidden by the printing layer, △ indicates that the base was slightly visible through the printing layer but was still usable, and × indicates that the base was clearly visible through the printing layer and was therefore unusable.
In addition, in the column for evaluating defects during lamination in Figure 4, ◯ indicates a state in which there are no air bubbles in the laminate surface and there are no problems with adhesion, △ indicates a state in which air bubbles (voids) are visible with a microscope but there are no problems with design or adhesion, and × indicates a state in which air bubbles (voids) are visible with the naked eye and there is poor adhesion.

4, it can be said that a thickness of 3 μm or more of the printed layer 20 can maintain good design. Also, it can be said that a thickness of 12 μm or less of the printed layer 20 can be thermally laminated with almost no air bubbles mixed in.
Furthermore, by comparing the results of Comparative Examples 3 to 5 with the Examples, it was confirmed that the effect of the storage modulus of the base material layer 10 at 165°C being smaller than the storage modulus of the transparent resin layer 30 at 165°C was fully exerted.

Fig. 5 is a micrograph showing a cross section of the decorative sheet 1. Note that Fig. 5 is upside down compared to Figs. 1 to 3.
The decorative sheet 1 illustrated in FIG. 5 has a base layer 10 made of PVC with a thickness of 150 μm, a transparent resin layer 30 made of a laminate of an acrylic resin film (45 μm) with a thickness of 50 μm and a fluororesin film (5 μm), and a printing layer 20 with a thickness of 6 μm, which corresponds to Example 2 in FIG. 4.
As shown in FIG. 5, it was confirmed that the entire printed layer 20 was embedded in the base material layer 10 in the decorative sheet 1 of this embodiment.

(Reference example)
Decorative sheets were produced in the same manner as in Example 2, except that the thermal lamination temperatures were set to 145°C, 155°C, 165°C, and 175°C. The laminate strength (adhesion) between the transparent resin layer 30 and the substrate layer 10 of the produced decorative sheets was confirmed. The decorative sheets produced by thermal lamination at a set temperature of 145°C suffered interfacial failure at the bonding interface between the transparent resin layer 30 and the substrate layer 10, resulting in weak laminate strength. The decorative sheets produced by thermal lamination at set temperatures of 155°C, 165°C, and 175°C suffered cohesive failure within the transparent resin layer 30 or the substrate layer 10, resulting in strong laminate strength. The laminate strength (adhesion) was confirmed using the following procedure. Before thermal lamination, adhesive tape (Nichiban Cellotape (registered trademark)) was applied to a portion of the surface of the substrate layer 10 that would be bonded to the transparent resin layer 30. The substrate layer 10 with adhesive tape attached is placed on the transparent resin layer 30 and thermally laminated. The surface of the substrate layer 10 with the adhesive tape attached is not bonded to the transparent resin layer 30, and the surface of the substrate layer 10 without the adhesive tape is bonded to the transparent resin layer 30. After a certain time has passed after thermal lamination, the portion of the transparent resin layer 30 that is not bonded to the substrate layer 10 is held and slowly peeled at 180° toward the portion of the transparent resin layer 30 that is bonded to the substrate layer 10.

In the decorative sheets produced by thermal lamination at set temperatures of 145°C, 155°C, and 165°C, most of the printed layer 20 (more than 70% of the total) was embedded in the base layer 10. In the decorative sheets produced by thermal lamination at a set temperature of 175°C, part of the printed layer 20 was not embedded in the base layer 10. The transparent resin layer 30 of Example 2 had a storage modulus of 2.4 MPa at 145°C, 5.4 MPa at 155°C, 4.7 MPa at 165°C, and 0.8 MPa at 175°C. The base layer 10 of Example 2 had a storage modulus of 1.8 MPa at 145°C, 1.4 MPa at 155°C, 1.1 MPa at 165°C, and 0.8 MPa at 175°C. In addition, the decorative sheet produced by thermal lamination at a set temperature of 175°C had a portion of the printed layer 20 that was not embedded in the base layer 10, but the evaluation above showed that it had strong lamination strength (adhesion). However, from the perspective of long-term reliability, it is preferable that the majority of the printed layer 20 (70% or more of the entire layer) be embedded in the base layer 10.

The above reference examples show that by focusing on the storage modulus at 165°C of the transparent resin layer 30 and the substrate layer 10, making the storage modulus at 165°C of the substrate layer 10 smaller than that of the transparent resin layer 30, and then thermally laminating the transparent resin layer 30 and the substrate layer 10 at a set temperature of 150°C or higher and 170°C or lower, a decorative sheet with high laminate strength and good adhesion, in which the majority of the printed layer 20 is embedded in the substrate layer 10, can be obtained. Decorative sheets with good adhesion are important for ensuring durability in outdoor environments when used for the exterior of vehicles such as automobiles and train bodies. It is also important for decorative sheets for uses other than exterior applications to have durability that can withstand a variety of usage environments.

In the above-described manufacturing method, the printing layer 20 is printed on the surface of the base layer 10, and then thermally laminated to the transparent resin layer 30. The manufacturing method of the decorative sheet 1 is not limited to this, and may also be a process of printing the printing layer 20 on the surface of the transparent resin layer 30, and then thermally laminating it to the base layer 10.

As explained above, with the decorative sheet 1 of this embodiment, the printed layer 20 is embedded in the base layer 10, resulting in a decorative sheet with high designability and excellent adhesion between the base layer 10 and the transparent resin layer 30. Furthermore, the decorative sheet 1 of this embodiment does not require the provision of an adhesive layer or the like between the base layer 10 and the transparent resin layer 30, so it can be manufactured inexpensively with a simple configuration.

1, 2 Decorative sheet 10 Base layer 20 Printed layer 21 Gap 30 Transparent resin layer 40 Adhesive layer 100 Decorative sheet (comparative example)

Claims (8)

a substrate layer;
a printing layer that is partially printed and that is disposed on the base layer;
a transparent resin layer laminated on the base layer with the printed layer sandwiched therebetween;
A decorative sheet comprising:
The thickness of the base layer is 80 μm or more and 180 μm or less,
the printing layer contains an acrylic resin, has a thickness of 3 μm or more and 6 μm or less, and is at least partially embedded in the base material layer;
the transparent resin layer contains an acrylic resin,
The decorative sheet has a storage modulus at 165°C of the base layer that is smaller than the storage modulus at 165°C of the transparent resin layer. The decorative sheet according to claim 1 ,
The storage modulus of the base layer at 165°C is 1.5 MPa or less.
Decorative sheet. The decorative sheet according to claim 1 or 2,
The storage modulus of the transparent resin layer at 165°C is 4 MPa or more and 15 MPa or less.
Decorative sheet. The decorative sheet according to any one of claims 1 to 3,
the transparent resin layer has an acrylic resin layer located on the substrate layer side and a fluororesin-containing layer located on the surface opposite to the substrate layer side;
Decorative sheet. The decorative sheet according to any one of claims 1 to 4 ,
The base layer contains 31 parts by mass or more and 45 parts by mass or less of a polyester plasticizer relative to 100 parts by mass of a vinyl chloride resin.
Decorative sheet. The decorative sheet according to any one of claims 1 to 5 ,
The printing layer is entirely embedded in the base material layer.
Decorative sheet. The decorative sheet according to any one of claims 1 to 6 ,
Decorative sheet for automobile bodies. A method for manufacturing the decorative sheet according to any one of claims 1 to 7 ,
forming the printing layer on the base material layer or the transparent resin layer;
a step of thermally laminating the transparent resin layer onto the base layer with the printed layer sandwiched therebetween at a temperature of 150°C or higher and 170°C or lower;
A method for manufacturing a decorative sheet comprising: