HK1102569A - Sheet for decoration simultaneous with injection molding and decorated resin molding - Google Patents

Description

Sheet for simultaneous decoration and injection molding and decorated resin molded body

Technical Field

The present invention relates to a sheet for simultaneously decorating a molded article during an injection molding process (hereinafter the sheet may be referred to as "a decorative sheet for simultaneous decoration and injection molding"), and also relates to a decorated resin molded article. More particularly, the present invention relates to a laminate-type decorative sheet suitable for forming a decorated resin molded article by simultaneous decoration and injection molding, and to a decorated resin molded article made using the decorative sheet.

Background

Conventionally, simultaneous decoration and injection molding are often used to decorate a resin molded body having a surface of a complicated shape (e.g., a three-dimensionally curved surface) (see, for example, patent documents 1 and 2). Simultaneous decoration and injection molding is a method of combining a decorative sheet placed in a mold with a molten resin injected into a cavity of the mold during injection molding, thereby decorating the surface of a resin molded body. In general, simultaneous decoration and injection molding methods are largely classified into a laminate decoration method and a transfer decoration method according to the structure of a decorative sheet to be combined with a resin molded body.

In the laminate decoration method, the entire decoration sheet including a base film (base film) and a decoration layer provided thereon is laminated on the surface of a resin molded body so that the decoration sheet is bonded to the molded body. The decorative sheet used is a decorative laminate sheet.

An example of a simultaneous decoration and injection molding method of the laminate is described below with reference to fig. 2 and 3. Fig. 2 and 3 are explanatory views showing an example of a molding step of the simultaneous decoration and injection molding method. The simultaneous decorating and injection molding apparatus 60 comprises a female mold 70 and a male mold 80, the male mold 80 being arranged transversely with respect to the female mold 70 so as to face the female mold 70. The female mold 70 has a cavity 72 with a shape corresponding to the contour of the molded body to be formed, and the female mold 70 further includes a suction hole 74 extending through the mold 70 and opening to the cavity 72. The female die 70 is arranged to reciprocate in a direction toward and away from the male die 80 by means of a reciprocating device 75 formed of, for example, a fluid pressure cylinder. The male mold piece 80 has a core section 82 inserted into the cavity 72 and includes a gate 84 therein for injecting molten resin into the cavity. If desired, a reciprocatable heating plate 90 is provided between the female mould 70 and the male mould 80.

In order to simultaneously perform decoration and injection molding by means of the device 60, first, the decorative sheet 100 is set on the female mold 70 so as to face the male mold, and if necessary, the decorative sheet 100 is heated and softened by the heating plate 90 at an appropriate temperature. Next, the decorative sheet 100 is sandwiched between the female mold 70 and the heating plate 90, thereby closing the opening of the cavity 72. The thus closed cavity is evacuated through the suction holes 74 provided in the female mold 70, and if necessary, compressed air is supplied to the sheet through the vents provided in the heating plate 90. The two molds are typically heated to about 30 to about 50 ℃.

By this method, as shown in fig. 3, the decorative sheet 100 is stretched along the inner wall of the cavity 72 so as to be brought into close contact. This process is commonly referred to as "preforming", in which the softened sheet is typically stretched up to about 200%. Next, the heating plate 90 is removed, and as shown in fig. 3, the female mold 70 is moved toward the male mold 80 so that the molds are joined together, and then the molds are clamped. Thereafter, the fluidized resin molding material P is injected into the cavity formed between the female mold 70 and the male mold 80 through a gate 84 provided in the male mold 80 until the material fills the cavity, and thus injection molding is performed.

By this method, the decorative sheet 100 placed in the female mold 70 is connected and bonded with the resin thus injected. After the injection molding is completed, the molds are separated from each other, and the molded body having the decorative sheet 100 coated on the outer surface is removed from the molds. Thus, laminate decoration is completed.

In the above-described simultaneous decoration and injection molding method, in order to form a good molded article, it is an important requirement that the decorative sheet 100 can be stretched along the inner walls of the cavity 72 so as to be brought into close contact (i.e., moldability of the sheet) during preforming or injection of the molten resin, and that the decorative sheet is not deformed under the stretching to an extent exceeding that required to make the sheet fit to the shape of the mold, which deformation may be caused by, for example, a vacuum/pressure action or a tension due to the pressure or shear stress of the molten resin. These requirements are very important for molding by means of a mold having a large depth, because the decorative sheet is subjected to deep drawing.

For deep drawing molding (i.e., where the percentage of stretch of the decorative sheet is high), it is generally necessary to decorate such resin injection molded articles to obtain a drawn shape corresponding to a percentage of stretch of the decorative sheet of about 200 to about 400%. In order to meet such a demand, for example, a decorative sheet is proposed which is formed of a material having a yield point and receiving a stress of a certain level or higher after the yield point (see the claim of patent document 3), and a decorative sheet for molding formed of a laminate of two or more layers, the sheet exhibiting a peel strength of a certain level or higher at the interface between the sheet and a resin to be molded, wherein a transparent acrylic film is provided on the film bonded to the resin, and a pattern is formed between the acrylic film and the film bonded to the resin (see the claim of patent document 4). In order to sufficiently conform to the irregular surface shape of the molded article, the above-mentioned decorative sheet for molding exhibits an elongation at break (percentage of stretch) of about 150 to 200% or more, or at most about 400% in a temperature range of 100 to 120 ℃, to which the decorative sheet is heated during the preforming or injection molding.

Generally, a decorative sheet of a laminate type having an area exceeding the surface area of the molded article is bonded to the molded article. Therefore, the decorative sheet must be subjected to a step called "trimming" to cut or remove an unnecessary portion generated along the periphery of the molded article. Such trimming is carried out at about 0 to about 40 c, typically at room temperature (about 25 c). The above decorative sheet disclosed in patent document 3 or 4 exhibits an elongation at break (tensile percentage) of about 150 to about 200% or more when measured at 100 to 120 ℃, and generally exhibits an elongation at break (tensile percentage) of up to 20% or more when measured at room temperature. When such a decorative sheet exhibiting an elongation at break (percent stretch) of up to 20% or more when measured at room temperature is used, the decorative sheet poses a problem that an unnecessary portion of the decorative sheet generated along the periphery of the molded article cannot be successfully cut during trimming, so that the unnecessary portion of the decorative sheet remains on the molded article, or the decorative sheet comes off at the end of the molded article.

Meanwhile, when a decorative sheet exhibiting low elongation at break when measured at 100 to 120 ℃ is used, it is easy to trim the sheet because the sheet generally exhibits low elongation at break when measured at room temperature. However, when such a decorative sheet is used for deep drawing molding, the sheet cannot sufficiently conform to surface irregularities (surface irregularities) of a molded article, and sometimes the sheet breaks during printing.

Patent document 1: japanese patent publication (kokoku) No. S50-19132

Patent document 2: japanese patent publication (kokoku) No. S61-17255

Patent document 3: japanese patent No.2690258

Patent document 4: japanese patent No.2965973

Disclosure of Invention

In view of the above, an object of the present invention is to provide a laminate type decorative sheet suitable for forming a decorated resin molded article by simultaneous decoration and injection molding; that is, a decorative sheet having good conformability (conformability) with the molding surface of a mold during preforming, which is not easily subjected to wrinkles, blisters, breakage, etc. when laminated and bonded with a resin molded body by injection molding, and which is easily trimmed. It is another object of the present invention to provide a decorated resin molded article formed using the decorative sheet.

The inventors of the present invention have conducted intensive studies in order to achieve the object of the present invention, and as a result, have found that the above-mentioned problems can be solved by means of a decorative sheet for simultaneous decoration and injection molding, which sheet has an elongation at break falling within a specific range when measured at 25 ℃ and a specific or higher level when measured at 120 ℃. The present invention has been completed based on the above findings.

Accordingly, the present invention provides:

(1) a laminate type decorative sheet for simultaneous decoration and injection molding, comprising a base film and at least one decorative layer provided on the base film, the decorative sheet having an elongation at break of 3 to 10% when measured at 25 ℃ and an elongation at break of 200% or more when measured at 120 ℃;

(2) the decorative sheet for simultaneous decoration and injection molding as described in the above (1), which has an elongation at break of 3 to 7% when measured at 25 ℃;

(3) the decorative sheet for simultaneous decoration and injection molding as described in the above (1) or (2), which has an elongation at break of 200 to 400% when measured at 120 ℃;

(4) the decorative sheet for simultaneous decoration and injection molding according to any one of the above (1) to (3), wherein the base film is formed of an acrylic resin composition;

(5) the decorative sheet for simultaneous decoration and injection molding according to the above (4), wherein the acrylic resin composition is a resin composition containing polyacrylate and/or polymethacrylate as a main component; and

(6) a decorated resin molded article comprising a resin molded body and the decorative sheet as described in any one of (1) to (5) above, said sheet being bonded to the molded body, wherein the decorative layer of the decorative sheet is bonded to the molded body.

According to the present invention, there can be provided a decorative sheet for simultaneous decoration and injection molding, which is suitable for forming a decorated resin molded article by simultaneous decoration and injection molding; that is, a decorative sheet having good conformability to the molding surface of a mold during preforming, which is not easily subjected to wrinkles, blisters, cracks, and the like when laminated and bonded to a resin molded body by injection molding, which is not broken during printing and which is easily trimmed after molding. After the trimming, no excess portion of the decorative sheet remains on the molded article, and no peeling of the decorative sheet occurs at the edge portion of the molded article.

A high-quality decorated laminate-type resin molded article can be provided by simultaneous decoration and injection molding using the decorative sheet.

Drawings

Fig. 1 is a cross-sectional view showing a structural example of the decorative sheet of the present invention.

Fig. 2 is an explanatory view partially showing an example of a molding step of the simultaneous decoration and injection molding method.

Fig. 3 is an explanatory view partially showing an example of a molding step of the simultaneous decoration and injection molding method.

Description of the reference numerals

1. Base film

2. Decorative layer

3. Adhesive layer

100. Decorative sheet

60. Device for simultaneous decoration and injection molding

70. Female die

72. Hollow cavity

74. Air extraction hole

75. Reciprocating device

80. Male die

82. Core segment

84. Pouring gate

90. Heating plate

P. resin molded body material

Detailed Description

The decorative sheet for simultaneous decoration and injection molding of the present invention comprises a base film and at least one decorative layer provided thereon, and if necessary, further comprises a bonding layer. The decorative sheet has, for example, a cross-sectional structure shown in fig. 1.

The decorative sheet for simultaneous decoration and injection molding of the present invention is characterized in that the sheet has an elongation at break of 3 to 10% when measured at 25 ℃. When the elongation at break measured at 25 ℃ is less than 3%, the sheet is easily sheared, but the strength is low. Therefore, sometimes the sheet material will break due to a stretching force applied to the base film when the decorative layer is formed on the base film by printing, or the sheet material will break when the sheet material is fed into an apparatus for preforming or simultaneous decoration and injection molding. Sometimes, breakage tends to occur during the process of manufacturing the base film, and difficulties are encountered in rolling up the sheet.

Meanwhile, when the elongation at break measured at 25 ℃ exceeds 10% (particularly 20% or more), it is difficult to perform trimming; that is, the sheet cannot be cut along the periphery of the molded article during the trimming process, and thus a part of the sheet remains on the molded article or peeling of the sheet occurs at the end of the molded article. Trimming is generally relatively easy when the elongation at break, measured at 25 ℃, is greater than about 10% to about 20%. However, depending on the shape of the molded article, the tensile portion of the sheet is oriented by preforming, and the breaking strength or elongation at break will increase, resulting in difficulty in cutting the sheet during trimming. The elongation at break measured at 25 ℃ is preferably 3 to 7% from the viewpoint of easier and more reliable trimming.

The term "elongation at break" as used herein means the elongation at break measured in all directions including MD (flow direction during formation of the base film) and TD (perpendicular direction to MD) on the surface of the decorative sheet for simultaneous decoration and injection molding. The same applies to the case where the elongation at break is measured at a temperature other than 25 ℃.

The decorative sheet for simultaneous decoration and injection molding of the present invention is characterized in that the sheet has an elongation at break of 200% or more when measured at 120 ℃. A decorative sheet meeting this requirement has good moldability and good conformability to the molding surface of a mold during the preforming process. There is no particular limitation on the maximum elongation at break measured at 120 ℃, but an elongation at break of about 400% is sufficient to manufacture a commonly used molded article.

Further, since breakage of the base film or the like is unlikely to occur in a drying step performed when, for example, the decorative layer is printed on the base film, the decorative sheet is expected to have some flexibility when the resin molded article bonded by means of the decorative sheet is removed from the mold. Therefore, the elongation at break measured at 40 ℃ is preferably 10% or more. In contrast, from the viewpoint of registration (registering) to perform printing, it is preferable that in the drying step performed when the decorative layer is printed on the base film, the elongation of the decorative sheet is small. Therefore, the elongation at break measured at 40 ℃ is preferably 20% or less.

The elongation at break at each temperature described above was measured according to JIS K7127. At each temperature, the elongation at break was calculated from the length of the sample sheet that was not elongated and the length of the sheet measured by Tensilon at the time of elongation break of the sheet. More specifically, a test piece (width: 10mm, total length: 150mm, thickness: 0.125mm) was provided, and two parallel measuring lines (interval: 50mm) were formed in the central portion of the test piece. The initial distance between the chucks was adjusted to 100mm and the test rate was adjusted to 100 mm/min.

A variety of resins can be used as a base material constituting the base film of the decorative sheet for simultaneous decoration and injection molding of the present invention. Examples of the resin that can be used include acrylic resins; a thermoplastic polyester resin; polyolefin resins such as polyethylene, polypropylene, polybutylene and olefin thermoplastic elastomers; a styrene-based resin; an ABS resin; and a vinyl chloride resin. Among these resins, acrylic resins or thermoplastic polyester resins are preferred from the viewpoint of easily achieving the above-mentioned target elongation at break. In particular, acrylic resins are most preferable in view of various properties of the resin molded article, including transparency, appearance (e.g., gloss), weather resistance, chemical resistance, and surface hardness.

The resin used is preferably transparent or translucent so that the decorative layer described below can be viewed. The gloss of the resin can be adjusted by adding a matting agent.

Examples of acrylic resins suitable for use as the base resin include poly (meth) acrylates, (meth) acrylic resins, polyacrylamides, and polyacrylonitriles. Among them, poly (meth) acrylates are preferable from the viewpoint of, for example, transparency, heat resistance, chemical resistance and weather resistance. Specific examples of the poly (meth) acrylate include polymethyl (meth) acrylate, polyethyl (meth) acrylate, polypropyl (meth) acrylate, polybutyl (meth) acrylate, polyhexamethyl (meth) acrylate, polyoctyl (meth) acrylate, poly 2-ethylhexyl (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, methyl (meth) acrylate-styrene copolymer, and (meth) acrylate-based polyols obtained by copolymerization of (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate or cyclohexyl (meth) acrylate, and (meth) acrylate having a hydroxyl group in the molecule such as 2-hydroxyethyl (meth) acrylate or 2-hydroxy-3-phenoxypropyl (meth) acrylate. Among them, a methyl (meth) acrylate-butyl (meth) acrylate copolymer having a glass transition temperature of about 80 to about 105 ℃ is particularly preferred. The copolymerization ratio (mass ratio) of methyl (meth) acrylate to butyl (meth) acrylate is preferably 10/2 to 10/6, more preferably 10/2 to 10/4. The above acrylic resins may be used singly or in combination of two or more.

The base film having the above-mentioned specific elongation at break can be formed from such a base resin by various methods. For example, the elongation at break can be adjusted by forming a base film from an acrylic resin composition or a thermoplastic resin composition by adding a filler (for example, a rubber material such as an acrylic rubber or the above-mentioned matting agent) to a base resin (for example, an acrylic resin or a thermoplastic polyester resin). Among these fillers, a rubber material is most preferable from the viewpoint of easy control of elongation at break. Examples of the rubber material include acrylic rubber, butadiene rubber, and silicone rubber. Among them, acrylic rubber is most preferable in view of transparency of the base film.

Examples of the method of adding rubber to the base resin include a method of physically mixing the base resin with rubber, and a method of copolymerizing a monomer for preparing the base resin with a monomer constituting the rubber. The amount of the rubber added to the base resin is about 3 to about 30 parts by mass, preferably about 10 to about 20 parts by mass, based on 100 parts by mass of the base resin.

The amount of the filler (e.g., matting agent) added is appropriately determined in consideration of the type of the filler added or the type of the base resin used. The amount of the filler is usually 1 to 5% by mass, preferably 1 to 3% by mass, based on the whole of the obtained resin composition.

The elongation at break measured at a certain temperature can be adjusted by controlling the orientation of the base film. Generally, in the orientation direction, the film is easily broken, and its elongation at break is reduced. In contrast, in the direction perpendicular to the orientation direction, the film is hard to break, and the elongation at break thereof increases.

The thickness of the base film is about 50 to about 300 μm. A thickness of 50 μm or more is preferred from the viewpoint of deep drawing moldability and surface smoothness, while a thickness of 300 μm or less is preferred from the viewpoint of printability and manufacturing cost. From the above viewpoint, the thickness of the base film is more preferably 50 to 200. mu.m.

The above-mentioned base film may be colored with a coloring agent (e.g., a dye or a pigment) if necessary. Any known colorant may be used. Examples of the coloring agent that can be used include inorganic pigments such as titanium white, carbon black, red iron oxide, cobalt blue, and chrome yellow; organic pigments such as phthalocyanine blue, isoindolinone and quinacridone; metallic pigments such as aluminum powder; pearlescent pigments, such as mica powder coated with titanium dioxide; and a dye.

The resin composition for forming the base film may contain various additives, if necessary. Examples of the additives include antioxidants, ultraviolet absorbers, light stabilizers, anti-friction agents, lubricants, plasticizers, antistatic agents, flame retardants, colorants, antifungal agents, and antibacterial agents. The additives to be incorporated into the resin composition may be appropriately selected from known additives in consideration of the intended use of the decorated resin molded article of the present invention.

When the decorated resin molded article of the present invention is used, for example, in an application requiring weather resistance, it is preferable to impart weather resistance to the base film. Therefore, at this time, the above-mentioned resin composition (which is a material forming the base film) preferably contains, for example, an organic ultraviolet absorber such as benzotriazole-based, benzophenone-based or salicylate-based ultraviolet absorbers; an inorganic ultraviolet absorber, such as zinc oxide, cerium oxide, or titanium oxide, in the form of fine particles having an average particle size of about 0.2 μm or less; or light stabilizers, such as hindered amine light stabilizers.

The adhesive layer constituting the decorative sheet for simultaneous decoration and injection molding of the present invention may be formed of any material that can be selected according to the type of resin constituting the resin molded body. When, for example, the resin molded body is formed of a styrene-based resin such as an acrylonitrile-styrene-butadiene copolymer (ABS) resin, an acrylic resin or polyvinyl chloride, the adhesive layer is preferably formed of an acrylic resin, a vinyl chloride-vinyl acetate copolymer or a mixture thereof. When the resin molded body is formed of a polyolefin resin, the adhesive layer is preferably formed of chlorinated polypropylene or a two-component curable urethane resin. The two-component curable polyurethane resin contains a polyol as a base material and an isocyanate as a crosslinking agent (curing agent). Examples of the polyol having two or more hydroxyl groups in the molecule used include polyethylene glycol, polypropylene glycol, acrylic polyol, polyester polyol, polyether polyol, polycarbonate polyol and polyurethane polyol. The isocyanate used is a polyvalent isocyanate having two or more isocyanate groups in the molecule. Examples of the polyvalent isocyanate which can be used include aromatic isocyanates such as 2, 4-tolylene diisocyanate, xylylene diisocyanate and 4, 4' -diphenylmethane diisocyanate; aliphatic (or alicyclic) isocyanates such as 1, 6-hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated diphenylmethane diisocyanate; and adducts and oligomers of any of the above isocyanates (e.g., toluene diisocyanate adduct and toluene diisocyanate trimer).

The decorative layer constituting the decorative sheet for simultaneous decoration and injection molding of the present invention is used to provide characters, numerals (figures) or symbols on the surface of the resin molded body, or to color the surface. The thickness of the decorative layer is usually 0.1 to 20 μm.

The decorative layer is typically formed using an ink. As with conventional inks, the inks used contain: an excipient formed of a binder resin or similar material; a colorant (e.g., a pigment or dye); and additives added as appropriate. The colorant may be a known colorant used in the above-described base film. The decorative layer can be formed using the ink by a known technique such as printing technique (e.g., gravure, screen, offset, or inkjet printing) or hand drawing. The decorative layer may have any pattern; for example, a wood grain pattern (e.g., a cross-grain or a straight-grain pattern), a stone pattern (e.g., a marble or granite pattern), a tile pattern (tile pattern), a brick pattern (brick pattern), a texture pattern (texture pattern), a character pattern (character pattern), a geometric pattern, or a monochrome pattern (solid color pattern).

The binder resin used in the above ink may be any resin, which is selected according to the resin composition used to form the base film. For example, when the base film is formed of an acrylic resin composition, it is preferable that the binder resin is a mixture of a vinyl chloride-vinyl acetate copolymer and an acrylic resin. When the base film is formed of a thermoplastic resin composition, it is preferable that the binder resin is a two-component curable polyurethane resin. The vinyl chloride-vinyl acetate copolymer used generally has a vinyl acetate content of about 5 to about 20 mass% and an average degree of polymerization of about 350 to about 900. The vinyl chloride-vinyl acetate copolymer may be further copolymerized with a carboxylic acid (e.g., maleic acid or fumaric acid), if desired.

Examples of the above-mentioned acrylic resin include acrylic resins such as polymethyl (meth) acrylate, polybutyl (meth) acrylate, methyl (meth) acrylate- (butyl (meth) acrylate copolymer, and methyl (meth) acrylate-styrene copolymer; and (ester) acrylic polyols obtained by copolymerization of (meth) acrylic esters (e.g., methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, or cyclohexyl (meth) acrylate) and (meth) acrylic esters having a hydroxyl group in the molecule (e.g., 2-hydroxyethyl (meth) acrylate or 2-hydroxy-3-phenoxypropyl (meth) acrylate). These acrylic resins may be used alone or in combination of two or more. The term "(meth) acrylate" as used herein refers to either acrylate or methacrylate. The mixing ratio (mass ratio) of the vinyl chloride-vinyl acetate copolymer to the acrylic resin is about 1/9 to about 9/1. The two-component curable polyurethane resin may be, for example, any of the resins described above as materials for forming the adhesive layer.

The decorative sheet for simultaneous decoration and injection molding comprises a base film and at least one decorative layer provided thereon, and if necessary, further comprises a bonding layer. The decorative sheet may include additional layers; for example, a concealing layer disposed on the bottom surface of the decorative layer, or a coating disposed on the top surface of the decorative layer.

The decorated resin molded article of the present invention is described below.

In the decorated resin molded article of the present invention, there is no particular limitation on the resin material constituting the resin molded body (i.e., the resin material used may be any resin) as long as the resin material is an injection-moldable thermoplastic resin or a thermosetting resin (including two-component curable resins). Examples of the thermoplastic resin material include vinyl polymers such as polyvinyl chloride and polyvinylidene chloride; styrene resins such as polystyrene, acrylonitrile-styrene copolymer, and acrylonitrile-butadiene-styrene copolymer resin (ABS resin); acrylic resins such as polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polyacrylonitrile; polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, ethylene glycol-terephthalic acid-isophthalic acid copolymer, and polybutylene terephthalate and polycarbonate resins. Examples of such thermosetting resins include two-component curable polyurethane resins and epoxy resins. These resins may be used alone or in combination of two or more. Such a resin may contain, if necessary, additives such as antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, flame retardants, plasticizers, fillers (for example, powders of inorganic substances such as silica, alumina, calcium carbonate, aluminum hydroxide, wood flour or glass fibers), lubricants, mold release agents, antistatic agents or colorants.

There is no particular limitation on the thickness of the resin molded body constituting the decorated resin molded article, and the thickness is determined according to the intended use of the decorated resin molded article. The thickness is generally from 1 to 5mm, preferably from 2 to 3 mm.

The resin for injection molding may be suitably colored with a colorant according to the intended use of the decorated resin molded article. The colorant used may be a known colorant similar to the colorant used in the base film described above.

The following describes a process for producing the above-mentioned decorated resin molded article of the present invention.

With the above decorative sheet of the present invention, a decorated resin molded article is produced by simultaneous decoration and injection molding. In the simultaneous decoration and injection molding, a decorative sheet previously placed in a mold is combined with a fluidized resin injected into a cavity of the mold in an injection molding process, thereby decorating the surface of a resin molded body.

The simultaneous decoration and injection molding can be carried out by conventionally known methods; for example, a method of preforming a decorative sheet for simultaneous decoration and injection molding, a method of not preforming a decorative sheet, a method of preheating a decorative sheet, or a method of not preheating a decorative sheet.

When the decorative sheet for simultaneous decoration and injection molding is subjected to deep drawing, it is preferable to perform a preforming step. In contrast, when the decorative sheet is subjected to shallow drawing, the preforming step may be omitted, and the decorative sheet may be molded by means of the pressure of the fluidized resin injected into the mold while the resin is injected. When the decorative sheet is molded by means of the pressure of the injection-molded resin, the step of preheating the sheet may be omitted, and the sheet may be heated by means of the heat of the resin. In the step of preforming the decorative sheet, generally, the injection mold is also used as a vacuum forming mold. However, in the preforming step, before the decorative sheet is fed into the injection mold, the sheet may be vacuum-formed by means of a vacuum forming mold different from the injection mold. In the preforming step, it is preferable that the injection mold is also used as a vacuum forming mold from the viewpoint of efficiency and accurate lamination of the sheet. The term "vacuum forming" as used herein includes vacuum pressure forming.

In the method for producing the decorated resin molded article of the present invention, the following steps are sequentially carried out: (A) a step of preforming a decorative sheet, (B) an injection molding step of laminating the decorative sheet on the resin molded body and bonding therewith; and (C) a step of removing the resin molded body laminated with the entire decorative sheet.

In the preparation method, the used injection mold can be of a male-female fit type; that is, a combination of a female mold (movable mold) having a molding surface of a predetermined shape and a male mold (fixed mold) having a protrusion; or may be a combination of a concave mold (movable mold) having a molding surface of a predetermined shape and a flat mold (fixed mold).

A preferred embodiment of the method of the present invention will be described in detail below with reference to fig. 2 and 3, which show the above-described molding step using a male-female mating type injection mold.

[ step (A) ]

Step (a) is a step of preforming the decorative sheet. In step (a), first, the decorative sheet 100 is arranged on a female mold (movable mold) 70 having a molding surface of a predetermined shape such that a base film of the decorative sheet 100 faces the molding surface. Next, the decorative sheet 100 is heated and softened by means of the heating plate 90. At this time, the heating temperature is preferably equal to or higher than a temperature near the glass transition temperature of the sheet and lower than the melting temperature (or melting point) of the sheet. Generally, heating the sheet is more preferably performed at a temperature close to the glass transition temperature of the sheet. The term "temperature near the glass transition temperature" refers to a temperature falling within a range of about 5 ℃ of the glass transition temperature. The term "temperature near the glass transition temperature" as used herein is generally from about 70 ℃ to about 130 ℃. The heating plate 90 may be a known heating plate, and may have a type such as a radiation heating type, a conduction heating type, or a dielectric heating type.

The decorative sheet 100 is sandwiched between the female mold 70 and the heating plate 90, and the opening of the cavity 72 is closed. The thus closed cavity is evacuated through the suction holes 74 provided in the female mold 70, and if necessary, compressed air is supplied to the sheet through the vent holes provided in the heating plate 90. The female mold 70 and male mold are typically heated to 30 to about 50 ℃.

By this method, as shown in fig. 2, the decorative sheet 100 is stretched along the molding surface of the female mold 70 so as to be brought into close contact, thereby preforming a sheet having a predetermined shape.

[ step (B) ]

In step (B), i.e., the injection molding step, the female mold 70, in which the decorative sheet 100 is brought into close contact with the molding surface as described above, and the male mold (stationary mold) 80 are clamped together, and then a fluidized resin molded body material is injected into the cavity formed between the molds, followed by curing the material, whereby the decorative sheet 100 is laminated on and bonded to the resin molded body thus formed. Specifically, the heating plate 90 is removed, and as shown in fig. 3, the female mold 70 is moved toward the male mold 80 by the shuttle 75 so that the molds are joined together, and then the molds are clamped. Thereafter, a fluidized resin molding material P is injected into the cavity formed between the female mold 70 and the male mold 80 through a gate 84 provided in the male mold 80 until the material fills the cavity, and then the material for injection molding is cured. When the resin molded body material P is formed of a thermoplastic resin, the material is fluidized by thermal melting and solidified by cooling. When the resin molding material P is formed of a thermosetting resin, the uncured liquid resin composition is cured by a chemical reaction. By this step, the decorative sheet 100 loaded in the female mold 80 is joined and integrated with the resin molded body thus formed.

[ step (C) ]

In step (C), the resin molded body laminated and bonded with the decorative sheet is removed from the injection mold.

In step (C), the female mold 70 is separated from the male mold 80; removing the resin molded body laminated with the entire decorative sheet 100 from the female mold; and trimming an unnecessary portion of the decorative sheet produced along the periphery of the resin molded body, thereby producing a desired decorated resin molded article.

In the case where the injection mold used is a combination of a concave mold (movable mold) having a molding surface of a predetermined shape and a flat mold (fixed mold), a decorated resin molded article is produced by a procedure similar to that described above. The decorative sheet used in the simultaneous decoration and injection molding method of the present invention may have the form of a single sheet or a continuous sheet.

Examples

The present invention is described in detail below with reference to examples, but the present invention should not be construed as being limited to the examples.

Example 1

(1) Preparation of decorative sheet

An acrylic film (main component: polymethyl methacrylate, acrylic rubber content: 30% by mass, ultraviolet absorber content: 1% by mass) having a thickness of 125 μm was melt-extruded via a T-die, and the film was brought into contact with a mirror roller (mirrorroller) at 100 ℃ at a resin temperature of 150 to 200 ℃ to impart printability to the film, thereby producing a continuous sheet-like acrylic film having a smooth printing surface. The elongation at break of the acrylic film when measured at 25 ℃ was 5% in both MD (flow direction during film formation) and TD (direction perpendicular to MD). The elongation at break of the acrylic film, measured at 120 ℃, was 240% in MD and 260% in TD.

Next, a wood grain pattern was formed on the acrylic film by rotogravure printing using a gravure ink, thereby producing a patterned ink layer used as a decorative layer. The ink used was prepared by adding a pigment comprising iron oxide red, chrome yellow and carbon black, and a dilution solvent (a 1: 1 (mass ratio) mixture of methyl ethyl ketone and ethyl acetate) to an acrylic resin binder. Next, a coating liquid containing an acrylic resin and a vinyl chloride-vinyl acetate copolymer in a mass ratio of 1: 1 and containing a diluting solvent (a 1: 1 (mass ratio) mixture of methyl ethyl ketone and ethyl acetate) was applied on the patterned ink layer, followed by drying, thereby forming an adhesive layer having a thickness of 4 μm. Thus, a decorative sheet was prepared.

Rotogravure printing was performed using a three-colour rotogravure press (comprising three printing elements) under the following conditions: printing speed: 40m/min, acrylic film tension: 20kg/m width. Continuous printing can be performed without causing film breakage.

(2) Preparation of decorated resin molded article

A decorated laminate-type resin molded article was produced by simultaneous decoration and injection molding using the decorative sheet and the resin molded body material (i.e., ABS resin [ "kralsostatic MTH-2" (trade name), product of Nippon a & L inc.) produced in the above-described (1) according to the steps shown in fig. 2 and 3. The preforming and injection molding conditions were as follows:

< preforming Condition >

Heating plate temperature: 300 deg.C

Distance between heating plate and film: 15mm (non-contact radiation heating)

Heating time: 5 seconds

Surface temperature of the decorative sheet: 120 deg.C

The molding method comprises the following steps: vacuum pressure forming

< injection Molding conditions >

Resin injection molding: ABS resin (as described above)

Resin temperature: 230 deg.C

Temperature of the die: 50 deg.C

Injection molding pressure: 140MPa

Injection molding time: 3 seconds

Cooling time: 20 seconds

Number of gates: 6

The laminate state of the decorative sheet in the thus-prepared decorated resin molded article was visually observed, and the moldability of the decorative sheet was evaluated based on the following criteria. Also, the trim performance of the decorative sheet was evaluated based on the following criteria. The results are shown in Table 1.

Evaluation Standard (moldability of decorative sheet)

O: no wrinkles, blisters, peeling and cracks were observed in the decorative sheet.

And (delta): slight wrinkles or blisters were observed in the decorative sheet.

X: any of wrinkles, blisters, peeling and breakage was observed in the decorative sheet, causing problems in practical use.

Evaluation criteria (clipping Performance)

O: the trimming was easy, and no flashing or peeling of the decorative sheet was observed at the end of the molded article.

And (delta): since the decorative sheet is not completely trimmed, a burr remains at the edge portion of the molded article.

X: peeling of the decorative sheet was observed at the edge portion of the molded article.

Example 2

An acrylic film B having the same composition as the acrylic film a except that the main component was polymethyl acrylate was used instead of the acrylic film a, and a continuous sheet-like acrylic film having a smooth printing surface was formed in a similar manner to example 1. The elongation at break of the acrylic film when measured at 25 ℃ was 8% in MD and 7% in TD. The elongation at break of the acrylic film, measured at 120 ℃, was 210% in MD and 200% in TD.

Next, in a similar manner to example 1, a patterned ink layer and an adhesive layer were provided on the acrylic film, thereby preparing a decorative sheet. A decorated laminate-type resin molded article was produced from the decorative sheet by simultaneous decoration and injection molding in a similar manner to example 1.

Table 1 shows the evaluation results of moldability, trim properties and continuous printability of the decorative sheet of the decorated resin molded article thus prepared.

Comparative example 1

An acrylic film similar to that used in example 1 was melt-extruded via a T-die and then stretched. The acrylic-based film was oriented in the MD by adjusting the stretching rate or the contact pressure against the mirror roll, thereby producing a base film having an elongation at break in the MD of 20% and in the TD of 7% when measured at 25 ℃. The base film had an elongation at break in the MD of 120% and in the TD of 200% when measured at 120 ℃.

A decorative sheet and a decorated resin molded article were prepared using the base film in a similar manner to example 1, and then the decorative sheet was evaluated in a similar manner to example 1. The results are shown in Table 1.

Comparative example 2

The method of example 1 was repeated except that an acrylic film C (thickness: 125 μm) formed solely of a polymethyl methacrylate resin was used in place of the acrylic film a, and a base film was prepared by casting an acrylic resin solution on a metal mirror tape, thereby obtaining a decorative sheet and a decorated resin molded article. The decorative sheet was evaluated in a similar manner to example 1. The results are shown in Table 1.

When the base film was continuously gravure-printed in a similar manner to example 1, the film broke due to solvent attack (solvent attack) or tension during printing, thereby making printing impossible on the base film. Therefore, the base film was subjected to sheet-fed screen printing.

The elongation at break of the acrylic film was 2% in MD and 2% in TD when measured at 25 ℃. The elongation at break of the acrylic film was 320% in MD and 350% in TD when measured at 120 ℃.

Comparative example 3

The procedure of example 1 was repeated except for using a commercially available polycarbonate film ("Ipiplon" (trade name), product of Mitsubishi Engineering-Plastics Corporation), thereby obtaining a decorative sheet and a decorated resin molded article. The decorative sheet was evaluated in a similar manner to example 1. The results are shown in Table 1.

The elongation at break of the polycarbonate film was 120% in the MD and 130% in the TD, when measured at 25 ℃. The elongation at break of the polycarbonate film was 200% in the MD and 240% in the TD, measured at 120 ℃.

TABLE 1

			Examples1	Example 2	Comparative example 1	Comparative example 2	Comparative example 3
								Elongation at Break (%)	25℃	MD	5	8	20	2	120
TD	5	7	7	2	130
						120℃	MD			240	210	120	320	200
TD	260	200	200	350	240
							Moldability of decorative sheet			○	○	△	○	○
Pruning Performance			○	○	×	○									×
							Continuous printability			○*1	○*1	○*1	×*2	○*1

○^*1: the film did not break under the printing conditions described in example 1 and was capable of continuous printing.

×^2*: the film broke under the printing conditions described in example 1 and was not printable.

Industrial applicability

The decorative sheet of the present invention exhibits good moldability and is therefore suitable for forming a decorated resin molded article by simultaneous decoration and molding. Also, the decorative sheet is easily trimmed. Use of the decorative sheet of the present invention enables production of a high-quality decorated resin molded article useful for various applications including vehicle interior materials, surface components for household appliances and sundries.

Claims (6)

1. Decorative sheet for simultaneous decoration and injection molding, which is of a laminate type and comprises a base film on which at least a decorative layer is provided, said decorative sheet having an elongation at break of 3 to 10% when measured at 25 ℃ and an elongation at break of 200% or more when measured at 120 ℃.

2. Decorative sheet for simultaneous decoration and injection molding according to claim 1, having an elongation at break, measured at 25 ℃, of 3 to 7%.

3. Decorative sheet for simultaneous decoration and injection molding according to claim 1 or 2, having an elongation at break of 200 to 400% measured at 120 ℃.

4. The decorative sheet for simultaneous decoration and injection molding according to any one of claims 1 to 3, wherein the base film is formed of an acrylic resin composition.

5. The decorative sheet for simultaneous decoration and injection molding according to claim 4, wherein the acrylic resin composition is a resin composition containing polyacrylate and/or polymethacrylate as a main component.

6. A decorated resin molded article comprising a resin molded body and the decorative sheet according to any one of claims 1 to 5, the decorative sheet being bonded to the molded body, wherein the decorative layer of the decorative sheet is bonded to the molded body.