JP2019081335A - Transfer sheet - Google Patents

Abstract

To provide a transfer sheet hardly generating crack in a release layer during transfer, and easily detaching a substrate sheet after transfer.SOLUTION: A transfer sheet has a substrate sheet, a release layer formed on the substrate sheet, and a transfer layer formed on the release layer, the release layer mainly containing one of a long chain alkyl resin or a modified melamine resin, thickness of the release layer is 0.01 μm to 1 μm with the long chain alkyl resin and 0.1 μm to 0.5 μm with the modified melamine resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transfer sheet.

  A transfer sheet 11 is conventionally known in which a release layer 14 and a transfer layer 13 are sequentially laminated on a base sheet 12 (see FIG. 2). The transfer layer 13 includes, for example, a protective layer 15, a pattern layer 16, and an adhesive layer 17. In the conventional transfer sheet, the release layer 14 contains a melamine resin, and the thickness thereof is about 5 μm (see, for example, Patent Document 1). In such a transfer sheet 11, for example, the transfer sheet is disposed between a pair of molds, injection molding is performed, and the base sheet 12 is peeled off, whereby a molded article to which the transfer layer is transferred can be obtained.

Unexamined-Japanese-Patent No. 2014-30969

  However, since the conventional transfer sheet has a thick release layer, for example, when the transfer sheet is deformed along the molding surface of the mold during injection molding, the release layer is forced to follow the molding surface and the release layer is cracked. As a result, cracks also occur on the surface of the transfer layer laminated to the release layer, and the appearance of the molded product becomes poor. In order to avoid cracks in the release layer, a method of forming the release layer with a flexible material is considered, but with this method, the adhesion between the release layer and the protective layer becomes strong, and the substrate sheet becomes difficult to peel off. was there. Also, no optimum material having flexibility and releasability has been found.

  The present invention has been made to solve the problems as described above, and it is an object of the present invention to provide a transfer sheet which is less likely to be cracked in a release layer at the time of transfer and which easily peels off a substrate sheet after transfer.

  Below, a plurality of modes are explained as a means to solve a subject. These aspects can be arbitrarily combined as needed.

The transfer sheet of the present invention is
A substrate sheet, a release layer formed on the substrate sheet, and a transfer layer formed on the release layer;
The release layer contains either a long chain alkyl resin or a modified melamine resin as the main component, and the thickness of the release layer is 0.01 μm or more and 1 μm or less for the long chain alkyl resin and 0.1 μm or more and 0.5 μm for the modified melamine resin It is below.

  Further, the transfer layer includes a protective layer formed on the release layer, and the peel strength between the release layer and the protective layer at an atmosphere temperature of 50 ° C. to 70 ° C. is 25 mN / 15 mm to 100 mN / 15 mm. It may be.

  The transfer sheet of the present invention comprises a substrate sheet, a release layer formed on the substrate sheet, and a transfer layer formed on the release layer, and the release layer is a long chain alkyl resin or a modified melamine One of the resins was used as the main component, and the thickness of the release layer was configured to be 0.01 μm or more and 1 μm or less for the long chain alkyl resin and 0.1 μm or more and 0.5 μm or less for the modified melamine resin. Therefore, in the transfer sheet of the present invention, a crack is not easily generated in the release layer at the time of transfer, and the base sheet is easily peeled off after the transfer.

It is a typical sectional view showing an example of the embodiment of the transfer sheet of the present invention. It is a typical sectional view showing the conventional transfer sheet.

  Hereinafter, an example of an embodiment of the transfer sheet of the present invention will be described with reference to the drawings.

  The transfer sheet of the present invention comprises a substrate sheet 2, a release layer 4 formed on the substrate sheet, and a transfer layer 3 formed on the release layer, and the release layer 4 is a long chain alkyl. The main component is either resin or modified melamine resin, and the thickness of the release layer 4 is 0.01 μm or more and 1 μm or less for the long chain alkyl resin and 0.1 μm or more and 0.5 μm or less for the modified melamine resin (FIG. 1) reference).

(Base sheet)
The base sheet 2 is to be peeled off from the object to be transferred together with the releasing layer 4 after the transfer sheet 1 is transferred to the object to be transferred. Examples of the material of the base sheet 2 include thermoplastic resins such as polypropylene resins, polyethylene resins, polyamide resins, acrylic resins, olefin resins, polyester resins, polyvinyl chloride resins, polycarbonate resins, and ABS resins. And laminates of these.

(Release layer)
The release layer 4 is to be peeled together with the base sheet 2 when the base sheet 2 is peeled from the material to be transferred. As a material of the release layer, either a long chain alkyl resin or a modified melamine resin is used as a main component. Here, the main component means that the proportion of the long chain alkyl resin or the modified melamine resin in the entire material of the release layer is 50% by weight or more. The release layer may be formed by a conventional printing method such as gravure printing, screen printing or offset printing, roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating Coating methods such as a method, curtain coating method, knife coating method, squeeze coating method, impregnation coating method, kiss coating method, spray coating method, calendar coating method, extrusion coating method and the like can be used.

  The long chain alkyl resin is a resin having a linear or branched alkyl group having 6 or more carbon atoms, particularly preferably 8 or more carbon atoms. Specific examples are not particularly limited, but long chain alkyl group-containing polyvinyl resin, long chain alkyl group-containing acrylic resin, long chain alkyl group-containing polyester resin, long chain alkyl group-containing amino resin, long chain alkyl group-containing resin Ether compounds, long-chain alkyl group-containing quaternary ammonium salts and the like can be mentioned. In view of the fact that the component derived from the release layer remains on the surface of the transfer layer 3 when the base sheet 2 is peeled off, it is preferable to be a polymer compound.

  The modified melamine resin is not particularly limited, but methylated melamine resin, butylated melamine resin, phenol modified melamine resin, epoxy modified melamine resin, acrylic modified melamine resin, ethylated melamine resin, propylated melamine resin, etc. Can be mentioned.

  The thickness of the release layer 4 is 0.01 μm or more and 1 μm or less if the long chain alkyl resin is a main component, and is 0.1 μm or more and 0.5 μm or less if the modified melamine resin is a main component. It is difficult to form a layer uniformly if it is less than 0.01 μm in the case of a long chain alkyl resin and less than 0.1 μm in the case of a modified melamine resin, and the substrate sheet and the protective layer adhere and the substrate sheet is peeled off. It becomes difficult to do. In addition, in the case of a long-chain alkyl exceeding 1 μm, and in the case of a modified melamine resin exceeding 0.5 μm, cracks easily occur in the releasing layer. If it exists in said range, the crack of the release layer 4 will not generate | occur | produce easily, and it will become the transfer sheet 1 which is easy to peel the base sheet 2. As shown in FIG.

  Since the main component of the release layer used in the present invention has a high crosslinking density or a small number of reactive groups, the ratio of bonding between the release layer 4 and the transfer layer 3 is smaller than that of the conventional transfer sheet. Therefore, although the thickness of the release layer is smaller than that of the conventional transfer sheet, it is possible to obtain a transfer sheet which is easily peeled off.

(Transfer layer)
The transfer layer 3 is a layer formed on the release layer 4. The transfer layer 3 may include a protective layer 5, a pattern layer 6, and an adhesive layer 7 (see FIG. 1). As the formation method of these layers, usual printing methods such as gravure printing, screen printing, offset printing, roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating Coating methods such as a method, curtain coating method, knife coating method, squeeze coating method, impregnation coating method, kiss coating method, spray coating method, calendar coating method, extrusion coating method and the like can be used.

  The protective layer 5 is a layer which becomes the outermost surface of a material to be transferred after peeling off the substrate sheet 2. As a material of the protective layer, thermoplastic resin such as acrylic resin, polystyrene resin, polyamide resin, chlorinated polyolefin resin, chlorinated ethylene-vinyl acetate copolymer resin, cyclized rubber, coumarone indene resin, etc. is used. be able to. When the protective layer is formed of such a thermoplastic resin, it is possible to impart chemical resistance and the like to the transferred material. In addition, as another material, it can be formed including any of a photocurable resin such as an ultraviolet curable resin, a radiation curable resin such as an electron beam curable resin, and a thermosetting resin. Examples of such resins include urethane acrylate resins, cyanoacrylate resins, epoxy acrylate resins, polyester acrylate resins, and resins obtained by adding an additive such as isocyanate to these resins. When the protective layer is formed of the above-described curable resin, physical properties such as durability and abrasion resistance can be imparted to the transferred material. The thickness of the protective layer 5 can be 0.5 μm to 10 μm.

  The pattern layer 6 may be formed on the entire surface, or may be formed in any pattern. The decorative property of a material to be transferred can be improved by the pattern layer 6. The material of the pattern layer 6 includes, for example, a resin such as an acrylic resin, a vinyl chloride vinyl acetate copolymer resin, a thermoplastic or thermosetting urethane resin, a polyester resin, and a pigment or dye added to the resin . Further, the pattern layer 6 may be, for example, a metal thin film layer formed by depositing a metal using a vacuum deposition method or a sputtering method, or may be formed by applying an etching method to the metal thin film layer . The pattern layer 6 may have a metallic design using, for example, an aluminum paste or a pearl pigment. The pattern layer 6 can be formed, for example, with a thickness of several hundred nm to several tens of μm. The pattern layer 6 may give a matte texture to the transferred object after peeling off the base sheet.

  As a material of the adhesive layer 7, a heat-sensitive or pressure-sensitive resin can be appropriately selected and used. For example, acrylic resin, polystyrene resin, polyamide resin, chlorinated polyolefin resin, chlorinated ethylene-vinyl acetate copolymer resin, cyclized rubber, coumarone indene resin and the like. These resins are appropriately selected according to the material of the material to be transferred. The thickness of the adhesive layer can be 0.1 μm to 50 μm.

  The transfer layer 3 includes the protective layer 5, and the peel strength between the release layer 4 and the protective layer 5 at an atmosphere temperature of 50 ° C. to 70 ° C. may be 25 mN / 15 mm to 100 mN / 15 mm. With a transfer sheet having a peel strength in this range, foil burrs are less likely to occur in actual injection molding, and the base sheet is easily peeled.

  In conventional transfer sheets, the peel strength was measured at room temperature. However, in the case of injection molding where a transfer sheet is actually used, the mold is heated, and the transfer sheet comes in contact with the mold at the time of molding. The transfer sheet in contact with the mold softens as the temperature rises, and foil burrs easily occur. Therefore, the peel strength in the conventional transfer sheet is an index for determining interface releasability at normal temperature, and is not an index for determining whether foil burrs are generated in actual injection molding. Therefore, in the present invention, the range of peel strength at the mold temperature set at the time of actual injection molding was specified.

The above-mentioned peel strength can be adjusted by using a material of the release layer as a main component of either a long chain alkyl resin or a modified melamine resin and making the thickness smaller than the conventional one. Further, when forming the release layer, the heat treatment conditions can be appropriately set while evaluating the damage to the substrate sheet and the release layer itself. Preferably, it is 170 ° C. for 15 seconds or more. In this way, the peel strength can be stabilized.
The long chain alkyl resin can be mixed with another resin, and a crosslinking agent such as isocyanate can also be used.

(Examples 1 to 6)
A release layer containing a long chain alkyl resin as a main component was formed on the substrate sheet, and a protective layer was formed on the release layer to obtain a transfer sheet. The thickness of the release layer and the material of the protective layer are as shown in Table 1. In addition, about the material of a protective layer, ultraviolet curable resin and acrylic resin were used.

(Examples 7 to 10)
A release layer containing methylated melamine resin as a main component was formed on the substrate sheet, and a protective layer was formed on the release layer to obtain a transfer sheet. The thickness of the release layer and the material of the protective layer are as shown in Table 1.

(Comparative example 1)
A release layer containing a long chain alkyl resin as a main component was formed on the substrate sheet, and a protective layer was formed on the release layer to obtain a transfer sheet. The thickness of the release layer and the material of the protective layer are as shown in Table 1, and the material of the protective layer is the same as in the example.

(Comparative Examples 2 to 3)
A release layer containing methylated melamine resin as a main component was formed on the substrate sheet, and a protective layer was formed on the release layer to obtain a transfer sheet. The thickness of the release layer and the material of the protective layer are as shown in Table 1, and the material of the protective layer is the same as in the example.

(Evaluation of crack)
A molded product (R100 mm long × 100 mm horizontal × 10 mm thick) with a R in the depression of 10 mm and the above transfer sheet are placed between a pair of molds, and the molds are clamped for molding, and the base sheet is peeled off. After that, the decorated molded product was visually observed, and it was judged whether or not a crack was generated in the protective layer of the decorated molded product in light of the following evaluation criteria.
:: no cracks occurred △: cracks were confirmed but there was no problem in use ×: cracks in some degree in use were found The results are shown in Table 1.

(Evaluation of foil burr)
The transfer sheet was placed in a mold provided with a foil burr test insert and injection molding was performed to integrate the injection resin and the transfer sheet. After cooling, the base sheet was peeled off from the object to be decorated made of resin, to obtain a decorated molded product in which the transfer layer is laminated on the surface of the object to be decorated. In addition, the insert for foil burr test is a flat plate of 60 mm long × 40 mm wide × 1.5 mm thick provided with four cylindrical protrusions (2 rows × 2 columns) in the center. The columnar projections are for forming holes in the decorative molded product, and have a diameter of 10 mm and are provided so as to have a distance of 10 mm.

The four pores formed in the decorative molded product were visually observed to determine how much the transfer layer adhered to each pore. If the transfer layer is attached to the vacancy portion, it is visually calculated what percentage of the vacancy is occupied by the transfer layer, and the sum (minimum value 0, maximum value 4) of them is evaluated by the following evaluation criteria. It was judged. For example, if the transfer layer is attached to half of the holes per hole, then 0.5 × 4 = 2, and the evaluation is Δ.
○: 0 to 1
Δ: 2 to 3
X: 4
The results are shown in Table 1.

(Evaluation of peeling defect)
A molded article (R100 mm long × 100 mm horizontal × 10 mm thick) with a R in the depression of 10 mm and the above transfer sheet are placed between a pair of molds, and the molds are clamped for molding. From this, when peeling the substrate sheet, it was judged whether or not it was easy to peel, that is, whether or not there was a peeling failure, in light of the following evaluation criteria.
:: No peeling failure occurred Δ: There is peeling failure but there is no problem in use ×: The result of peeling failure having some degree of problem in use is shown in Table 1.

(Measurement of peel strength)
The peel strength between the release layer and the protective layer was measured by the following method.
A polyester tape (31-B manufactured by Nitto Denko Corporation) was bonded to the adhesive layer, and pressed with a metal roller. Then, it cut out in width 15 mm and length 150 mm, and set it as the measurement sample. The measurement sample is set in a constant temperature chamber for tensile testing machine (TKC-R3-C manufactured by Orientec Co., Ltd.) set to a predetermined temperature, and the tensile testing machine (tensilon universal testing machine RTC-1210A manufactured by Orientech Co., Ltd.) The T-peel test was conducted under the following measurement conditions under the given temperature conditions.
The measurement conditions were set at a tensile speed of 1000 mm / min until the peel length was 200 mm, and the average value of the load with a peel length of 30 mm to 180 mm was taken as the peel strength.
The results are shown in Table 1.

  From the above results, in Examples 1 to 6, the thickness of the release layer is 0.01 μm or more and 1 μm or less, and in Examples 7 to 10, the thickness of the release layer is 0.1 μm to 0.5 μm. The following is the result and no cracking was generated in the release layer by molding in these ranges. In addition, when peeling the base sheet of the transfer sheet, peeling failure hardly occurred and it was easy to peel off. On the other hand, in Comparative Examples 1 and 2, since the peeling failure occurred, the crack could not be evaluated. The peeling failure occurs because the thickness of the release layer is as thin as 0.007 μm in the case of a long chain alkyl resin and 0.05 μm in the case of a modified melamine resin, so the release layer is not formed with a uniform thickness, It is considered that the substrate sheet and the protective layer are bonded at a place where the release layer is not formed. Moreover, although it was easy to peel off about Comparative Example 3, the film thickness of the mold release layer was 1 micrometer, and the crack has generate | occur | produced in the mold release layer by shaping | molding.

  Further, from the above results, in Example 3, the peel strength was 13 mN / 15 mm, and foil burrs were generated. In Examples 1 to 10, except for Example 3, the peel strength was in the range of 25 mN / 15 mm to 100 mN / 15 mm, and in this range, foil burrs were not generated or were at an acceptable level. In Comparative Example 3, the peeling strength was 25 mN / 15 mm, and the foil burr was at an acceptable level.

1, 11: transfer sheet 2, 12: base sheet 3, 13: transfer layer 4, 14: release layer 5, 15: protective layer 6, 16: pattern layer 7, 17: adhesive layer

Claims (2)

A substrate sheet, a release layer formed on the substrate sheet, and a transfer layer formed on the release layer;
The release layer contains either a long chain alkyl resin or a modified melamine resin as a main component, and the thickness of the release layer is 0.01 μm or more and 1 μm or less for the long chain alkyl resin and 0.1 μm for the modified melamine resin. A transfer sheet having a thickness of 0.5 μm or more.   The transfer layer includes a protective layer formed on the release layer, and the peel strength between the release layer and the protective layer under an atmosphere temperature of 50 ° C. to 70 ° C. is 25 mN / 15 mm to 100 mN / 15 mm. The transfer sheet according to claim 1, which is the following.

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