JP2005169654A - Molding method of thermoformable laminated sheet and molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding method capable of molding a thermoformable laminated sheet having mirror surface like metal gloss enhanced in brightness with good mold reproducibility while holding the original brightness thereof in a high holding ratio, and a molded product. <P>SOLUTION: The thermoformable laminated sheet, which is constituted by successively laminating a transparent or translucent thermoplastic film layer, a mirror surface like metal gloss ink layer containing metal thin film fine pieces and a support base material layer from a surface layer side, is subjected to matched-mold thermoforming at a thermoforming laminated sheet temperature lower than the glass transition temperature of the thermoplastic film layer by 15°C but higher than the glass transition temperature by 20°C. The molded product is obtained by this molding method. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for forming a laminated sheet having a high specularity, which is useful as a laminated sheet having high brightness and having a mirror-like metallic luster, and particularly useful as an exterior coating-free sheet for automobile-related members, building materials, home appliances, etc. It relates to a molded body.

  In general, when a colored resin molded member is manufactured, there are a method of kneading a pigment into the resin itself, coloring it and performing injection molding, and a method of performing spray coating after molding. In particular, when a metallic design is required, the coating method is often used rather than the coloring method because of the difficulty in kneading the pigment and the fact that the pigment flow trace is conspicuous. In the case of the coating method, if the coating film is baked and crosslinked, the effect of surface protection can be expected. However, since current paints mainly use volatile organic solvents, there is no solvent such as using water-based paints or powder paints from the viewpoint of protecting the working environment against discharge of volatile organic solvents and protecting the external environment. However, it is difficult to express a metallic design at present. On the other hand, a method has been introduced in which a colored sheet in which a moldable support resin layer is laminated instead of using a paint is integrally formed during injection molding. According to this method, it is possible to produce a resin-molded member having a metal design without solvent.

  As a sheet having a metallic design with high brightness, a laminated sheet obtained by dry laminating a polyethylene terephthalate film, a polypropylene film or the like deposited on aluminum is known. In addition, a laminated sheet having an acrylate emulsion layer containing aluminum particles having a scaly shape and a smooth surface is described (see, for example, Patent Document 1).

  However, although these sheets have a metallic design as a flat surface, the vapor deposition surface does not have sufficient spreadability, and therefore, when subjected to molding processing such as vacuum molding or in-mold molding, cracks and uneven gloss are produced. The design property of the metallic decorative layer was insufficient.

  Further, it has been proposed to use a laminated sheet having an ink film in which metal thin film strips are dispersed in a binder resin varnish (see, for example, Patent Document 2). According to this method, a high-luminance sheet having a high gloss value can be produced, and the spreadability during thermoforming can be improved. However, the gloss value of the sheet itself is significantly reduced by heating during vacuum forming, and there is a problem that it is not possible to obtain a molded product that maintains good luminance before heating.

JP-A-5-111991 JP 2002-46230 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a molding method and a molded body thereof which can be molded with good mold reproducibility while maintaining the original luminance of a laminate sheet for molding having a high-brightness mirror-like metallic luster capable of thermoforming. There is to do.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors, from the surface layer side, contain at least a transparent or translucent thermoplastic film layer for molding, a metal thin film strip and a binder resin to give a mirror-like metallic luster. It was obtained by performing a match mold molding in a low temperature region that cannot be shaped at a normal vacuum molding temperature, a laminated sheet for thermoforming with high brightness in which an ink layer and a supporting base material layer are laminated in this order. Even in the state of the molded body, the inventors have found that the mirror-like metallic luster having high luminance is maintained, and have completed the present invention.

That is, the present invention is a thermoforming in which a transparent or translucent thermoplastic film layer, a mirror-like metallic glossy ink layer containing metal thin film strips, and a supporting base material layer are laminated in this order from the surface side. A method for forming a laminated sheet for thermoforming, characterized in that a laminated sheet for molding is formed by match molding at a temperature of the laminated sheet for thermoforming in a temperature range of 15 ° C. to 20 ° C. higher than the glass transition temperature of the thermoplastic film layer I will provide a.
Moreover, this invention provides the molded object obtained by the shaping | molding method of the said laminated sheet for thermoforming.

According to the production method of the present invention, a decorative molded body that gives a high-brightness specular metallic luster design can be provided.

Hereinafter, a method for forming a laminated sheet for thermoforming by match molding according to the present invention and a molded body obtained by the forming method will be described in detail.

(Transparent or translucent thermoplastic film)
As the transparent or translucent thermoplastic film used in the present invention, a transparent or translucent single layer or multilayer film which may contain a colorant and which has a spreadability by heating is used.

  A film mainly composed of a thermoplastic resin having a softening point in the range of 30 to 300 ° C. is preferable in order to perform a heat forming process such as vacuum forming. For example, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, Thermoplastic resins such as acrylic resin, silicon-acrylic resin, ionomer, polystyrene, polyurethane, nylon, ethylene-vinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluorinate, polyvinylidene difluorate, and polycarbonate resin are preferably used. Among these, a film mainly composed of polyvinylidene difluorate, polycarbonate resin, or acrylic resin is preferable from the viewpoint of integral molding possibility and weather resistance. The thickness is not particularly limited, but is preferably in the range of 30 to 2000 μm, more preferably 50 to 500 μm, since the coating property of the ink protective layer is good.

(High gloss ink)
The ink used for the ink layer of the thermoformed laminated sheet used in the molding of the present invention is an ink having a mirror-like metallic luster (hereinafter referred to as high brightness) in which metal thin film strips are dispersed in a binder resin. It is called a property ink.) It is preferable that content with respect to the non volatile matter in the ink of a metal thin film piece is the range of 3-60 mass%. High-gloss inks using thin metal film strips are aligned with the metal thin film strips parallel to the surface of the object when the ink is printed or applied. Unobtainable high-brightness mirror-like metallic luster is obtained.

(Metal thin film strip)
Aluminum, gold, silver, copper, brass, titanium, chrome, nickel, nickel chrome, stainless steel, etc. can be used as the metal of the metal thin film strip used in the high gloss ink used in the ink layer. As a method for making a metal into a thin film, in the case of a metal having a low melting point such as aluminum, it is a foil if it has malleability, such as aluminum, gold, silver, copper, in the case of a metal having a high melting point and no malleability. , Sputtering and the like. Among these, the metal thin film strip obtained from the vapor deposition metal thin film is preferably used. The thickness of the metal thin film is preferably 0.01 to 0.1 μm, more preferably 0.02 to 0.08 μm. The size in the plane direction of the metal thin film pieces dispersed in the ink is preferably 5 to 25 μm, more preferably 10 to 15 μm. When the size is less than 5 μm, the brightness of the coating film becomes insufficient, and when it exceeds 25 μm, the metal thin film strips are difficult to orient and decrease in brightness, and ink is printed or applied by gravure or screen printing. Doing so may cause clogging of the plate.

  In the following, a method for producing a metal thin film strip will be described by taking a particularly preferable vapor deposition method as an example. A polyolefin film, a polyester film, etc. can be used for the support body film which vapor-deposits a metal. First, a release layer is provided on the support film by coating, and then a metal is deposited on the release layer so as to have a predetermined thickness. A top coat layer is applied to the surface of the deposited film to prevent oxidation. The same coating agent for forming the release layer and the top coat layer can be used.

  Resin used for a peeling layer or a topcoat layer is not specifically limited. Specific examples include cellulose derivatives, acrylic resins, vinyl resins, polyamides, polyesters, EVA resins, chlorinated polypropylene, chlorinated EVA resins, petroleum resins, and the like. Solvents include aromatic hydrocarbons such as toluene and xylene, aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane, esters such as ethyl acetate and propyl acetate, methanol, ethanol and isopropyl alcohol. Alcohols, ketones such as acetone and methyl ethyl ketone, and alkylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether can be used.

  The metal vapor-deposited film is immersed in a solvent that dissolves the release layer and the topcoat layer and stirred. After the metal vapor-deposited film is peeled from the support film, the metal vapor-deposited film is further stirred to reduce the size of the metal thin film strip. Set to 5 to 25 μm, filter and dry. The solvent is not particularly limited except that it dissolves the resin used for the release layer or the topcoat layer. Even when the metal thin film is formed by sputtering, the metal thin film can be formed by the same method as described above. When using a metal foil, it may be pulverized to a predetermined size with a stirrer as it is in a solvent.

  The metal thin film strip is preferably surface-treated in order to enhance dispersibility in the ink. Examples of the surface treating agent include organic fatty acids such as stearic acid, oleic acid, and palmitic acid, and cellulose derivatives such as methylsilyl isocyanate, nitrocellulose, cellulose acetate propionate, cellulose acetate butyrate, and ethyl cellulose. To adsorb on the surface of the metal thin film strip.

(Binder resin)
As the binder resin, those usually used in conventional gravure ink, flexo ink, screen ink, paint or the like can be used. Specifically, for example, acrylic resins for paint, vinyl chloride resins, vinylidene chloride resins, vinyl chloride-vinyl acetate resins, ethylene-vinyl acetate resins, polyolefin resins, chlorinated olefin resins, polymerization resins such as ethylene-acrylic resins, Alternatively, a polyurethane resin for paint, a polyamide resin, a urea resin, an epoxy resin, a polyester resin, a petroleum resin, a cellulose derivative resin and the like are preferably used. In addition, those obtained by chemically bonding polar resins such as carboxylic acid group, phosphoric acid group, sulfonic acid group, amino group and quaternary ammonium base to these resins may be used or used in combination.

(Additive)
High gloss ink used in the ink layer, if necessary, defoaming, settling prevention, pigment dispersion, fluidity modification, antiblocking, antistatic, oxidation in the ink, unless it impairs design and spreadability. Various additives used in conventional gravure inks, flexo inks, screen inks, paints and the like can be used for the purpose of prevention, light stability, ultraviolet absorption, internal crosslinking and the like. Examples of such additives include coloring pigments, dyes, waxes, plasticizers, leveling agents, surfactants, dispersants, antifoaming agents, chelating agents, polyisocyanates, and the like.

(solvent)
As the solvent used in the high-gloss ink used in the ink layer, a known and commonly used solvent used in conventional gravure ink, flexo ink, screen ink, paint or the like can be used. Specifically, for example, aromatic hydrocarbons such as toluene and xylene, aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane, esters such as ethyl acetate and propyl acetate, methanol, ethanol, isopropyl alcohol and the like Alcohols, ketones such as acetone and methyl ethyl ketone, and alkylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether.

(Preparation method of high brightness ink)
Generally, in order to stably disperse the ink blending raw material, the pigment and other additives are finely divided to submicron by kneading using a roll mill, ball mill, bead mill, or sand mill. However, the metal thin film strip to be incorporated in the high gloss ink used for the ink layer of the thermoforming laminated sheet having excellent specularity used in the molding of the present invention has a size of 5 to 25 μm. Is preferable. When the above-mentioned kneaded meat is performed, the metal thin film pieces become fine particles, and the metallic luster is extremely lowered. Therefore, in the present invention, it is desirable not to perform kneading, but to simply mix the above-mentioned blending raw materials into an ink. For this purpose, for the purpose of improving dispersibility, it is preferable to surface-treat the metal thin film strip as described above.

(Printing or coating method)
The ink layer of the laminated sheet for molding of the present invention, the ink that may be further laminated to the ink layer, and the printing or coating method of the adhesive are printing methods such as gravure printing, flexographic printing, screen printing, gravure coater, Coating methods such as a gravure reverse coater, flexo coater, blanket coater, roll coater, knife coater, air knife coater, kiss touch coater, kiss touch reverse coater and comma coater, comma reverse coater, and micro gravure coater can be used. If the ink film thickness is too thin, the concealability tends to be inferior and the design property tends to be impaired. If it is too thick, the orientation of the metal thin film strips tends to be non-uniform. For this reason, as a film thickness of an ink layer, 5 micrometers or less are preferable, 0.05-5 micrometers is more preferable, Especially preferably, it is 0.5-3 micrometers.

(Supporting substrate layer)
The thermoplastic resin constituting the base material layer of the present invention is preferably a film mainly composed of a thermoplastic resin having a softening point in the range of 30 to 300 ° C. in order to perform a molding process by a match mold molding method. Examples of the thermoplastic resin include acrylonitrile / butadiene / styrene (ABS) resin, acrylonitrile / acrylic rubber / styrene (AAS) resin, acrylonitrile / ethylene rubber / styrene (AES) resin, polyethylene (PE) resin, polypropylene (PP ) -Based resins, PVC-based (PVC) -based resins, etc., as well as olefin-based elastomers (TPO), PVC-based elastomers (TPVC), styrene-based elastomers (SBC), urethane-based elastomers (TPU), polyester-based elastomers (TPEE) ), Polyamide elastomer It can be a thermoplastic elastomer (TPE), etc. (TPAE) and the like. Among these, polypropylene resin, polyethylene resin, blended products thereof, AAS resin, ABS resin, and the like are more excellent because of the excellent formability of molded products having complicated shapes such as automotive exterior parts. Preferably used. These resins may contain rubber modifiers such as EPR, SBS, SEBS for the purpose of improving impact strength and the like. Although the thickness is not particularly limited, the thickness of the support base material layer is preferably 10 μm to 2000 μm.

(Inorganic filler)
The laminated sheet for molding is thermoformed to form a three-dimensional shaped body. At this time, if the molding shrinkage of the thermoplastic resin used for the supporting base material layer and the thermoplastic film layer laminated thereon is different, the molded body is deformed and a good shape cannot be maintained. In this case, if an inorganic filler is added to the resin of the supporting base layer, the molding shrinkage can be controlled to be small, and the difference in the molding shrinkage between the supporting base layer and the ink layer can be reduced. Deformation after molding can be prevented.

However, when the particle size of the inorganic filler is large, irregularities are generated on the surface of the support base material layer, and the irregularities also affect the ink layer laminated thereon. If the supporting base material layer has irregularities, it becomes difficult for the metal thin film strips contained in the ink layer to be oriented substantially parallel to the base material layer, resulting in disordered orientation. For this reason, the metallic luster by a thin metal thin film piece is impaired.
Although there is no particular limitation, since the support base material layer which is the base of the ink layer is required to be smooth, the average particle size of the inorganic filler to be added is 4 μm or less, preferably 2 μm or less.

  The amount of the inorganic filler added to the resin of the support base layer is preferably 5% by mass to 60% by mass, and more preferably from the viewpoint of the balance between moldability and molding shrinkage.

  The kind of the inorganic filler used in the present invention is not particularly limited, and examples thereof include talc, calcium carbonate, clay, diatomaceous earth, mica, magnesium silicate, silica and the like.

(Colorant in the supporting base material layer)
It is preferable to add a colorant to the support base material layer, since the concealability of the base color of the molded body is improved. The colorant to be used is not particularly limited, and conventional inorganic pigments, organic pigments and dyes used for coloring general thermoplastic resins can be used according to the intended design. For example, inorganic pigments such as titanium oxide, titanium yellow, iron oxide, complex oxide pigments, ultramarine, cobalt blue, chromium oxide, bismuth vanadate, carbon black, zinc oxide, calcium carbonate, barium sulfate, silica, talc; azo Pigments, phthalocyanine pigments, quinacridone pigments, dioxazine pigments, anthraquinone pigments, isoindolinone pigments, isoindoline pigments, perylene pigments, perinone pigments, quinophthalone pigments, thioindigo pigments and diketopyrrolo Organic pigments such as pyrrole pigments; metal complex pigments and the like. In addition, it is preferable to use one or two dyes mainly selected from the group of oil-soluble dyes.

  The amount of colorant added to the base material layer varies depending on the type of colorant and the desired thickness and color tone of the sheet, but in order to ensure the concealment of hue and background color and maintain impact strength The content of the colored layer is preferably in the range of 0.1 to 20% by mass and more preferably in the range of 0.5 to 15% by mass. When the colorant is added in excess of 20% by mass, the impact strength is lowered, and when the amount of the colorant added is less than 0.1%, there is a tendency that the hiding property of the hue and the background color is not sufficient.

(Ink protective layer)
The laminated sheet for thermoforming excellent in specularity used in the molding of the present invention has improved heat resistance, solvent resistance, design, weather resistance, etc. between the transparent or translucent thermoplastic film and the ink layer. For this purpose, one or more ink protective layers may be provided. The type of resin that can be used in the ink protective layer is not particularly limited as long as it does not impair the spreadability. However, acrylic resins are used from the viewpoints of easy adjustment of the crosslink density, weather resistance, adhesion to transparent thermoplastic film, etc. Resins are preferred. The crosslinking mechanism is not particularly limited, and in the case of acrylic resins, UV curing, EB curing, hydroxyl group-containing copolymer / isocyanate curing, silanol / water curing, epoxy / amine curing, etc. can be used. From the viewpoints of ease, weather resistance, reaction rate, presence or absence of reaction by-products, production cost, etc., hydroxyl group-containing copolymer / isocyanate curing is preferred.
The ink protective layer can be a colored layer in order to impart design properties. In this case, the amount of the colorant added varies depending on the type of the colorant, the target color tone and the thickness of the protective layer, but the total light transmittance of the protective layer is 20 so as not to conceal the ink layer having a specular metallic luster. % Or more, and the total light transmittance is more preferably 40% or more.

  As the colorant, a pigment is preferable. The pigment to be used is not particularly limited, and known and commonly used pigments such as colored pigments, metallic pigments, interference color pigments, fluorescent pigments, extender pigments and rust preventive pigments can be used.

  Examples of the color pigment include quinacridone series such as quinacridone red, azo series such as pigment red, phthalocyanine series organic pigments such as phthalocyanine blue, phthalocyanine green, and perylene red; and inorganic pigments such as titanium oxide and carbon black. Examples of the metallic pigment include aluminum powder, nickel powder, copper powder, brass powder, and chromium powder.

  Examples of the interference color pigment include pearl luster-like pearl mica powder and pearl luster-colored pearl mica powder. Examples of the fluorescent pigment include quinacridone, anthraquinone, perylene, perinone, and diketopyrrolopyrrole. , Isoindolinone, condensed azo, benzimidazolone, monoazo, insoluble azo, naphthol, flavanthrone, anthrapyrimidine, quinophthalone, pyranthrone, pyrazolone, thioindigo, anthanthrone, dioxazine , Organic pigments such as phthalocyanine and indanthrone, metal complexes such as nickel dioxin yellow and copper azomethine yellow, metal oxides such as titanium oxide, iron oxide and zinc oxide, barium sulfate and calcium carbonate Metal salt, carbon black, aluminum Inorganic pigments fine mica.

  Addition of plasticizers, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, lubricants, etc., to the thermoplastic resin sheet (C) containing the colorant, as long as the impact strength and moldability are not impaired. An additive may be blended, and these additives may be used alone or in combination of two or more.

(Laminated)
The ink layer and the supporting substrate layer are laminated via an adhesive layer, and as a bonding method, a dry lamination method using a conventional solvent-type adhesive, a wet lamination method, a hot melt lamination method, etc. are used to form a laminated sheet. I can do it.

  Components constituting the adhesive include conventional phenol resin adhesives, resorcinol resin adhesives, phenol-resorcinol resin adhesives, epoxy resin adhesives, urea resin adhesives, polyurethane adhesives and polyaromatics. Type thermosetting resin adhesives, reactive adhesives using ethylene unsaturated carboxylic acid, etc., vinyl acetate resin, acrylic resin, ethylene vinyl acetate resin, polyvinyl alcohol, polyvinyl acetal, vinyl chloride, nylon and cyano Examples thereof include thermoplastic adhesives such as acrylate resins, rubber adhesives such as chloroprene adhesives, nitrile rubber adhesives, SBR adhesives, and natural rubber adhesives. In particular, an acrylic urethane adhesive is preferred because the adhesiveness between the acrylic resin and the polypropylene resin is good and the followability of elongation during vacuum forming is good.

  As a method for applying these adhesives, a gravure coater, a gravure reverse coater, a flexo coater, a blanket coater, a roll coater, a knife coater, an air knife coater, a kiss touch coater, a comma coater, or the like can be used.

The coating amount of the adhesive, the adhesive strength is sufficient, for drying also good, preferably in the range of 0.1 to 30 g / ^{m 2,} particularly preferably 2 to 10 g / ^{m 2.}
When it is less than 2 g / m ² , the adhesive strength is weakened, and when it is more than 10 g / m ² , the drying property is lowered. The thickness of the adhesive layer is preferably in the range of 0.1 to 30 μm, more preferably 1 to 20 μm, and particularly preferably 2 to 10 μm.

  In addition, for the purpose of improving the affinity with the adhesive, the adhesion surface of the support base material layer is a surface treatment such as plasma treatment, corona treatment, flame treatment, electron beam irradiation treatment, roughening treatment, ozone treatment, A dry plating process such as vacuum deposition, sputtering, or ion plating may be performed.

(Adhesive)
Moreover, it can replace with an adhesive bond layer and can also provide an adhesive layer. As the adhesive, acrylic, rubber, polyalkyl silicon, urethane, polyester, and the like are preferably used.

(Surface protective layer)
In the laminated sheet for thermoforming of the present invention, the surface layer side at the time of molding has performance such as designability, abrasion resistance, scratch resistance, weather resistance, contamination resistance, water resistance, chemical resistance and heat resistance. One or more transparent, translucent or colored clear topcoat layers can be provided for imparting. As the topcoat agent, a lacquer type, a crosslinking type by isocyanate or epoxy, a UV crosslinking type or an EB crosslinking type is preferably used as long as the spreadability of the laminated sheet for thermoforming is not impaired.

(Sheet processing)
The laminated sheet for thermoforming excellent in specularity used in the molding of the present invention can be used as a surface layer in various molding methods. For example, after placing a transparent or translucent thermoplastic film on the opposite side of the mold and forming a molded body having a three-dimensional shape by thermoforming, insert it into the female mold side in the injection mold, It can be molded by an insert injection molding method integrated with an injection resin.

(Match mold molding)
The thermoforming method used for the forming method of the thermoformed laminated sheet having excellent specularity is match mold forming using a match mold die composed of a pair of male and female dies. This match molding is characterized in that molding is performed by matching a female mold with a male mold so as to sandwich a sheet heated in a heating zone. The mold used here is usually provided with a vacuum port as an escape path for air in the mold, but vacuum suction may be performed supplementarily using this hole. By performing this match mold molding at a low temperature, it is possible to mold a molded body that maintains a mirror-like metallic luster having a high brightness similar to that of the sheet.

  The setting conditions for the match molding are not particularly limited, but when a far infrared heater is used, heating is performed at a heater temperature of 200 to 500 ° C. and an indirect heating time of about 5 to 30 seconds. The upper limit temperature of the glass is a glass transition temperature (hereinafter referred to as Tg) + 20 ° C. measured by the plastic transition temperature measurement method shown in JIS K7121, because a molded product having a high specular metallic luster is obtained. Is more preferable, and Tg + 10 ° C. is more preferable. Further, the lower limit temperature of the heated sheet is preferably Tg-15 ° C. or higher, more preferably Tg or higher, because the mold reproducibility of the molded body becomes good. In this temperature range, the sheet has high rigidity and is difficult to stretch, so care must be taken not to drag the sheet into the mold with a strong clamping force. Although it is necessary to determine the mold temperature while confirming the appearance and the degree of shrinkage of the molded body, it is preferable that the cooling time is 20 to 100 ° C. and the match mold mold is 5 to 600 seconds.

(Insert molding)
Next, the obtained molded body is placed in a mold so that its mirror surface is in contact with the female mold, and a thermoplastic resin having adhesiveness to the base material layer is injection-molded on the back surface of the preform. One-piece molding. The resin temperature of the injection resin is not particularly limited, but is preferably about 180 to 250 ° C. at which injection is possible as long as it is a thermoplastic resin such as polypropylene resin or ABS resin. The mold temperature is preferably about 20 to 80 ° C. for both the male mold and the female mold. However, when warping or the like occurs in the injection molded body, it is necessary to modify the male mold and the female mold by providing a temperature gradient.

(Specular metallic luster and gloss retention)
The method for forming a laminated sheet for thermoforming according to the present invention can maintain the gloss value of the laminated sheet for thermoforming before forming. When the ratio (%) of the gloss value measured by the above-mentioned method to the gloss value of the laminated sheet for thermoforming before molding is defined as the gloss value retention rate, it is preferably 60% or more in the molding method of the present invention. Can be obtained. More preferably, 70% or more can be obtained.
Moreover, it is preferable that the gloss value is 600% or more, more preferably 700% or more, and still more preferably 800% for exhibiting a mirror-like metallic luster.
For this reason, in order that a molded object exhibits a high specular metallic luster, the gloss value of the laminated sheet for thermoforming used in the molding method of the present invention and the molded body obtained by the molding method of the present invention is 600% or more. More preferably, it is 700% or more, More preferably, it is 800% or more.

  Hereinafter, the present invention will be described with specific examples, but the present invention is not limited thereto. In addition, the physical-property evaluation in an Example and a comparative example was performed with the following measuring method or test method. In the examples, “part” and “%” are both based on mass.

(Sheet gloss value evaluation method)
The gloss value of the sheet was determined by a 20 ° gloss measurement method in accordance with JIS-K7105, with an incident angle of 20 ° and a light receiving angle of 20 °. In addition, Nippon Denshoku VGS-300A was used for the gloss meter.
(Glossiness evaluation method)
The gloss value was measured by a measuring method in accordance with JIS-K7105 using 20 ° gloss.
(Glossiness evaluation method for molded products)
The brightness of the molded body was evaluated by the following standard by measuring 20 ° gloss of the top surface of the trapezoidal molded body by a thermoforming method according to JIS-K7105. The trapezoidal mold used in this case has a female mold with an opening of 120 × 90 mm, a bottom of 66 × 51.7 mm and a depth of 25 mm, and a male mold with an opening of 120.3 × 90.5 mm and a bottom of 66.6 × 52.3 mm. The depth was 25 mm, and molding was performed using both male and female molds during match molding, and molding was performed using only a female mold during vacuum molding. The sheet was placed so that a transparent or translucent thermoplastic film layer on the mirror surface side of the sheet came on the female mold surface, and evaluation was performed with the convex surface on the mirror surface side of the obtained trapezoidal shaped body as the top surface. Further, when the laminated sheet for thermoforming was molded, the expansion ratio of the top surface was about 110% when molded with a match mold, and about 130% when molded with a vacuum molding method. In addition, the expansion | deployment rate here was represented as 130% when the whole area becomes 1.3 time compared with the original area.
A: A gloss retention of 80% or more with respect to the gloss value of the thermoformed laminated sheet before molding.
○: A gloss retention of 60% or more with respect to the gloss value of the thermoformed laminated sheet before molding.
X: Gloss retention of less than 60% with respect to the gloss value of the thermoformed laminated sheet before molding.

However, the gloss retention referred to in the present invention is the ratio (%) calculated by the following formula for the gloss value measured by the above method for the molded product after molding relative to the gloss value of the thermoformed laminated sheet before molding.
Gloss retention (%) = Gloss value of molded article after molding / Gloss value of laminated sheet for thermoforming before molding × 100

(Mold reproduction evaluation method)
Using the molded body produced by the luminance evaluation method, the R reproducibility of the corner portion was measured, and the reproducibility of the mold was evaluated according to the following criteria. The measured corner radius was 5R.
A: Maintaining the same R reproduction as the mold.
A: A mold reproducibility of 80% or more.
(Triangle | delta): The thing with a mold reproduction rate of 70% or more.
X: The mold reproduction rate is less than 70%.

(Method for evaluating whitening of molded products)
Using the molded body produced by the luminance evaluation method, the presence or absence of whitening due to low temperature molding was evaluated at the corners and the like according to the following criteria.
○: No whitening occurs.
X: Whitening occurred.

(Production of laminated sheet for thermoforming with excellent specularity)
(1) Aluminum thin film strip Nitrocellulose (HIG7) was dissolved in a mixed solvent of ethyl acetate: isopropyl alcohol = 6: 4 to obtain a 6% solution. The solution was applied onto a polyester film with a gravure plate having a screen line number of 175 lines / inch and a cell depth of 25 μm to form a release layer. After sufficiently drying, aluminum is vapor-deposited on the release layer to a thickness of 0.04 μm, and the same nitrocellulose solution as that used for the release layer is applied to the deposited film surface under the same conditions as in the release layer. The top coat layer was formed by coating.
The deposited film is immersed in a mixed solvent of ethyl acetate: isopropyl alcohol = 6: 4 to peel the aluminum deposited film from the polyester film, and then the aluminum deposited film is pulverized with a stirrer so that the size becomes about 150 μm. An aluminum thin film strip was prepared.

(2) Aluminum thin film strip slurry Aluminum thin film strip 10 parts Ethyl acetate 35 parts Methyl ethyl ketone 30 parts Isopropyl alcohol 30 parts The above mixture was mixed and stirred, and 5 parts of a nitrocellulose solution having the following composition was added.
Nitrocellulose (HIG 1/4) 25%
Ethyl acetate: isopropyl alcohol = 6: 4 mixed solvent 75%
While maintaining the temperature at 35 ° C. or lower, the above mixture is stirred using a turbo mixer until the size of the aluminum thin film pieces becomes 5 to 25 μm, thereby preparing an aluminum thin film piece slurry (nonvolatile content 10%). did.

(3) Surface protective layer and ink protective layer Weight average molecular weight: Indicates a polystyrene equivalent value of the GPC measurement result.
Solid content: 1 g of a sample was taken in an aluminum dish, spread thinly and uniformly with toluene, air-dried, further dried in a hot air dryer at 108 ° C. for 1 hour, and calculated from the weight after drying.
The hydroxyl value was calculated from the monomer charge composition as the KOH neutralization amount, the polymer Tg was measured by DSC, and the acid value was measured by 0.05 mol · dm-3 potassium hydroxide-toluene solution titration method.
(Hydroxyl-containing copolymer)

  850 parts of butyl acetate and 1 part of perbutyl Z (trade name, manufactured by NOF Corporation, t-butyl peroxybenzoate) are added to a reaction vessel equipped with a temperature controller, a nitrogen introducing tube, a dropping device (2 units), and a stirring device. After charging and nitrogen substitution, the temperature was raised to 110 ° C. over 1.5 hours.

  Separately, 660 parts of methyl methacrylate, 150 parts of t-butyl methacrylate and 190 parts of 2-hydroxyethyl methacrylate (hereinafter referred to as monomer solution), 200 parts of isobutyl acetate, and perbutyl O (trade name, manufactured by NOF Corporation) , T-butyl peroxy-2-ethylhexanoate) and 2 parts of perbutyl Z (trade name, manufactured by NOF Corporation, t-butyl peroxybenzoate) are mixed well (hereinafter referred to as catalyst solution). Each was charged into a dropping device and immediately purged with nitrogen.

  The above monomer solution and catalyst solution were dropped in a reaction vessel under a nitrogen atmosphere over 5 hours while monitoring the reaction temperature so as not to increase rapidly. As a result of continuing stirring for about 15 hours after the completion of dropping, a resin composition (O-1) having a solid content of 60% was obtained. The weight average molecular weight of the obtained resin was 100,000, the hydroxyl value of the solid content was 79 KOHmg / g, and Tg was 95 ° C.

(Polyisocyanate compound)
“BURNOCK DN-981” (trade name, manufactured by Dainippon Ink & Chemicals, Inc., isocyanurate ring-containing polyisocyanate, number average molecular weight of about 1000, non-volatile content 75% (solvent: ethyl acetate), functional group number 3, NCO concentration 13 ~ 14%) is the polyisocyanate compound.
(Surface protective layer and ink protective layer)
The hydroxyl group-containing copolymer and the polyisocyanate compound were blended and mixed at a ratio of 1: 1 to prepare a solution for the surface protective layer and the ink protective layer.

(4) Ink (Ink preparation)
Aluminum thin film slurry (non-volatile content 10%) 30 parts Binder resin Carboxylic acid-containing PVC-vinyl acetate resin 3 parts
("Vinylite VMCH" manufactured by UCC)
Carboxylic acid-containing urethane resin 7 parts (Dainippon Ink & Chemicals "Taiho Force NT810-45" nonvolatile content 45%)
Ethyl acetate 23 parts Methyl ethyl ketone 26 parts Isopropanol 10 parts The above was mixed to prepare an ink having an aluminum thin film strip concentration of 35 mass% in the nonvolatile content.

(5) Adhesive Two-component polyester urethane adhesive (two-component mixed adhesive “ELX-1004” and “KR-90” manufactured by Dainippon Ink & Chemicals, Inc.) at a ratio of 8: 2. The adhesive was adjusted.

(6) Support base material layer As a support base material layer, Sumitomo Chemical Co., Ltd. low density polyethylene (Sumikasen F101-1) is introduced from an extruder hopper, extruded from a T die at a processing temperature of 200 ° C, and heated to 40 ° C. After passing through the cast roll, winding and unstretched raw sheet A were produced.
Next, random PP (Noblen FS3611) manufactured by Sumitomo Chemical Co., Ltd. was introduced from an extruder hopper, extruded from a T-die at a processing temperature of 200 ° C., passed through a cast roll heated to 40 ° C., and wound up. A stretched original sheet B was produced.
Next, ABS (Clarastic MTH-2) manufactured by Japan A & L Co., Ltd. was introduced from the extruder hopper, extruded from a T-die at a processing temperature of 240 ° C., passed through a cast roll heated to 100 ° C., and wound up. The unstretched original fabric sheet C was manufactured.

(7) Transparent or translucent thermoplastic film layer A rubber-modified PMMA film D which is transparent as a transparent or translucent thermoplastic film layer and has a surface gloss value of 140%, pencil hardness H, Tg 104 ° C. (JISK7121), thickness 125 μm, and A rubber-modified PMMA film E having a gloss value of 149%, a pencil hardness of 2H, a Tg of 114 ° C. (JISK7121) and a thickness of 125 μm was used.
(8) Sheet lamination method A solution prepared for an ink protective layer and a surface protective layer is applied to a rubber-modified PMMA film using a micro gravure coater so as to have a dry film thickness of 2.0 μm, and then subjected to an aging treatment at 40 ° C. for 3 days. went. In addition, when applying a surface protective layer, after coating and drying an ink protective layer, it coats so that it may become thickness 10 micrometers on the opposite surface of an ink protective layer. Next, the ink layer was coated on the ink protective layer to a dry film thickness of 2.0 μm using a gravure coater. Separately, the adhesive surface of the supporting base material layer was subjected to corona treatment, and the above adhesive was applied using a # 20 bar coater. After laminating the ink layer and the base material support layer using a laminator set at 40 ° C., an aging treatment at 40 ° C. for 3 days was performed.

  (9) Match mold molding

The obtained laminated sheet with excellent specularity is clamped using a FE38PH small vacuum forming machine manufactured by Hermis Co., Ltd., then the sheet is indirectly heated from both sides, and after the heater is retracted, the female mold is raised. Thereafter, the male mold was lowered and a molded body was produced by a match mold molding method. The heater temperature on the lower surface was 270 ° C., the heater temperature on the upper surface was 230 ° C., and the sheet was molded after being heated to the sheet temperature shown in each example and comparative example by adjusting the heating time. The heater-sheet distance was 130 mm, the mold temperature was 90 ° C., and the vacuum / cooling time was 60 seconds.
(10) Vacuum forming After using the FE38PH small vacuum forming machine manufactured by Hermis Co., Ltd. to clamp the obtained laminated sheet having excellent specularity, the sheet is indirectly heated from both sides, and the heater is retracted. The female mold was raised and a compact was produced by vacuum forming. The heater temperature on the lower surface was 270 ° C., the heater temperature on the upper surface was 230 ° C., and the sheet was molded after being heated to the sheet temperature shown in each example and comparative example by adjusting the heating time. The heater-sheet distance was 130 mm, the mold temperature was 90 ° C., and the vacuum / cooling time was 60 seconds.

(11) Insert molding The top surface of the molded body obtained by match molding is brought into close contact so that the transparent or translucent thermoplastic film layer on the side of the sheet mirror is in contact with the female mold of the injection mold. After heating at a mold temperature of 40 ° C., a molten resin made of Novatec PP resin (trade name “TX1868H5”) heated to 200 ° C. is injected into the mold and integrally molded, and injection having a laminated sheet with excellent brightness A molded body was prepared. The injection molding machine is Sumitomo Nestal Injection Molding Machine Promat 80/40 manufactured by Sumitomo Heavy Industries, Ltd., and the mold is 65 mm × 40 mm × thickness 3 mm and 1.5 mm (thickness is 3 mm) from which a two-stage plate molding can be taken. And 1.5 mm two-stage stepped plate).

(Examples 1-8, Comparative Examples 1-8)
The layer structure is rubber-modified PMMA film layer / ink protective layer / ink layer / adhesive layer / supporting base material layer, of which the supporting base material layer and the transparent or translucent thermoplastic film layer (in Table 1, transparent layer) Is a laminated sheet for molding of 425 μm using the sheet shown in Table 1. The gloss value of the laminate sheet for molding using the transparent layer PMMA film D was 1080%, and the gloss value of the laminate sheet for molding using the transparent layer PMMA film E was 1100%. The resulting laminated sheet for molding was formed into a molded body by the match molding method (described as “match” in Table 1) and the vacuum forming method (described as “vacuum” in Table 1) under the above conditions. Body type reproducibility was evaluated. For reference, the gloss value of the sheet that has only been heated in the unformed part is also shown. The sheet temperature was measured with a radiation thermometer IT2-80 manufactured by Keyence Corporation.
The evaluation results are shown in Table 1.

Example 9
The layer structure is a surface protective layer / rubber-modified PMMA film layer / ink protective layer / ink layer / adhesive layer / supporting base material layer, of which the supporting base material layer B is the same as in Example 5. A laminated sheet for molding having a gloss value of 1080% and 430 μm was obtained. As a result of evaluating the brightness and mold reproducibility of the molded body by using the obtained laminated sheet for molding as a molded body by the match mold molding method under the above conditions, a molded body exhibiting good luminance was obtained. The top surface portion of the obtained molded body was cut out and subjected to integral injection molding by the method shown in the above insert molding method. As a result, a molded body showing good luminance was obtained.

As shown in the evaluation of Examples 1 to 7 shown in Table 1, the molded body by match mold molding has high brightness because it can be molded at low temperature in addition to obtaining good mold reproducibility at low temperature. It turns out that the molded object of is obtained. In addition, in the case where the supporting base material layer was not provided, mold reproducibility was accompanied by breakage at 95 ° C., but a good molded article was obtained even at a temperature 14 ° C. or more lower than the glass transition temperature (104 ° C.) of the used thermoplastic film layer. Obtained. From the comparison between Example 8 and Comparative Example 2, it can be seen that the Tg of the transparent layer is greatly related to the gloss value at the time of molding. Furthermore, it can be seen from Example 7 that a sufficient molded product can be obtained even with a surface protective layer, and that Example 9 has good brightness even after insert injection molding.
On the other hand, even when the match mold molding method is used, the temperature of the thermoformed laminated sheet during molding as in Comparative Example 1 is lower than the glass transition temperature (104 ° C.) of the used thermoplastic film layer by more than 20 ° C. And a whitening phenomenon occurs in a part of the transparent layer, resulting in a defect. On the other hand, when the temperature of the laminated sheet for thermoforming during molding becomes higher than the glass transition temperature (104 ° C.) of the used thermoplastic film layer by 20 ° C. or higher as in Comparative Example 2, the gloss value of the molded body decreases. And it turns out that the difference with the gloss value of the molded object obtained by vacuum forming is not seen.
From the above results, it can be seen that the method for producing a laminated sheet for thermoforming according to the present invention is an excellent production method capable of providing a molded product having a high gloss value and good mold reproducibility.

  The molded body molded by the molding method of the present invention is useful in the field having a mirror-like metallic luster with high brightness that does not require exterior coating and is used for applications such as automobile-related members, building material members, and household appliances.

Claims (6)

From the surface layer side, a transparent or translucent thermoplastic film layer, a mirror-like metallic glossy ink layer containing metal thin film strips, and a supporting base material layer are laminated in this order. A method for forming a laminated sheet for thermoforming, characterized by performing match molding at a temperature of the laminated sheet for thermoforming in a temperature range of 15 ° C to 20 ° C higher than a glass transition temperature of the thermoplastic film layer. The method for forming a laminated sheet for thermoforming according to claim 1, wherein the transparent or translucent thermoplastic film layer is a thermoplastic resin mainly composed of an acrylic resin. The method for producing a laminated sheet for thermoforming according to claim 1 or 2, wherein the supporting base layer is a thermoplastic resin whose main component is a resin selected from the group consisting of polypropylene resin, polyethylene resin and ABS resin. Gloss by molding when a thermoformed laminate sheet having a gloss value of 600% or more on the transparent or translucent thermoplastic film layer side of the thermoformed laminate sheet is molded with a match mold mold having a development rate of 110% The method for forming a laminated sheet for thermoforming according to any one of claims 1 to 3, wherein the value retention is 60% or more. The molded object obtained by the shaping | molding method in any one of Claims 1-4. The molded product according to claim 5, wherein the gloss value after molding is 600% or more.