JP5974328B2 - Biaxially oriented polyester film for in-mold transfer - Google Patents

Description

  The present invention relates to a biaxially oriented polyester film for in-mold transfer. More specifically, the in-mold transfer is most suitable for obtaining a resin molded product having a beautiful appearance without tearing or wrinkling during in-mold molding. The present invention relates to a biaxially oriented polyester film for in-mold transfer suitable for a substrate.

Biaxially stretched polyester film represented by polyester film has good mechanical strength, thermal characteristics, humidity characteristics and many other excellent characteristics, so it can be used in a wide range of fields such as industrial materials, magnetic recording materials and packaging materials. It is used.
Particularly in an in-mold transfer foil, the polyester film is useful as the substrate. This transfer foil is formed by laminating a release layer, a hard coat layer, a metal vapor deposition layer, an adhesive layer, and the like on one side as necessary, and has a function as a transfer foil.

  In these transfer foil transfer methods, a transfer foil film obtained by processing the transfer foil is set in an injection mold and a resin molded product is molded. At the same time, the transfer foil film is integrated and adhered to the surface. In addition, a so-called in-mold transfer method (simultaneous molding transfer method), which imparts functions such as decoration by transferring a pattern or other hard coat layer to a resin molded product, is widely known. A resin molded product obtained by such a transfer method is used for applications such as cellular phones, electrical products, and cosmetic containers (Patent Document 1).

  In recent years, these resin molded products have been increasingly demanded for complex shapes such as increased design and size, increased consumer efficiency, increased production efficiency, and increased molded product size and thickness. It has become to. Due to the tendency of such resin molded products, demands for films for in-mold transfer foils are increasing, and various studies have been made. For example, a study using a polyester film having a specific crystal structure (Patent Document 2), a study using a copolyester to make it easy to follow even complicated shapes by low crystallization (Patent Document 3), and deformation during molding Studies have been made on a film that retains mechanical strength such as stress and has excellent heat-resistant dimensional stability (Patent Document 4), and a film that can simultaneously satisfy high formability and heat-resistant dimensional stability (Patent Document 5). ing.

  However, as resin molded products become highly heat-resistant, larger, thicker, or three-dimensionally shaped, the heat applied to the film during molding and the flow of the molded resin become more complex, and the film used for in-mold transfer is stretched. There was a problem that it was torn or wrinkled.

JP 59-202830 A JP-A-5-269843 Japanese Unexamined Patent Publication No. 64-45699 JP 2009-203399 A JP 7-237283 A

  The present invention eliminates the problems of the prior art, and the resin molding has a beautiful appearance without tearing the transfer film or generating wrinkles during in-mold molding using a resin having a high molding temperature as the resin for injection molding. It is an object of the present invention to provide an in-mold transfer base film optimal for obtaining a product.

  In the conventional transfer foil polyester film, the transfer film is pushed away by a high-temperature injection resin during in-mold molding using a resin having a high molding temperature as a resin for injection molding, and the film is stretched. It has been found that since it breaks or wrinkles, it affects the appearance of the resin molded product. And as a result of intensive studies to solve the above problems, it is possible to eliminate the occurrence of film breakage and wrinkles by increasing the heat shrinkage rate of the film for transfer foil having a constant thickness in the high temperature region near the injection resin temperature. It was possible to provide a resin molded product having a beautiful appearance, and the present invention was completed.

That is, an object of the present invention is a biaxially oriented polyester for in-mold transfer, in which the heat shrinkage rate when heated at 180 ° C. for 30 minutes is 8% or more in both the vertical and horizontal directions, and the film thickness is 25 μm or more and 200 μm or less. Achieved by film.
In addition, the biaxially oriented polyester film for in-mold transfer of the present invention has, as a preferred embodiment thereof, a longitudinal breaking strength of the film of 280 MPa or more, a transverse breaking strength of 200 MPa or more, and a 5% elongation of the film in both directions. The stress is 110 MPa or more, the melting subpeak temperature (Tsm) of the film is 140 ° C. or more and 210 ° C. or less, the plane orientation coefficient of the film is 0.200 or more and 0.280 or less, polyethylene naphthalate The main component of the film is that the difference in heat shrinkage between the longitudinal direction and the transverse direction at 180 ° C. is 10% or less, and the heat shrinkage rate when heat-treated at 155 ° C. for 30 minutes is in the longitudinal and transverse directions. Both are 5% or less, and a primer layer is formed on at least the transfer foil processing side on the film. Ri, the primer layer is intended to be those that are applied in the film forming process of the polyester film, which include those comprising at least one of.
The present invention also includes an in-mold transfer foil including the biaxially oriented polyester film for in-mold transfer according to the present invention.

  According to the present invention, an in-mold suitable for obtaining a resin molded product having a beautiful appearance without tearing or wrinkling of a transfer film during in-mold molding using a resin having a high molding temperature as a resin for injection molding. A substrate film for mold transfer can be provided.

Sectional drawing of the metal mold | die used for moldability evaluation, and the shape which looked at the molded product obtained from the top are shown. FIG. 1 schematically shows an outline of a molding die, and detailed structures such as a gate and an ejector pin are not shown.

Hereinafter, the present invention will be described in detail.
[Polyester film]
The polyester film in the present invention is composed of a polyester obtained using aromatic dicarboxylic acid or its ester and glycol as main starting materials, and the main constituent of the film is preferably polyethylene terephthalate or polyethylene naphthalate. Here, the main component refers to 90% by weight or more based on the weight of the polyester film, more preferably 95% by weight or more, and still more preferably 97% by weight or more.

  These polyesters are preferably polyesters in which 80 mol% or more of the repeating structural units are ethylene terephthalate units or ethylene-2,6-naphthalenedicarboxylate units, and the content of such components is more preferably 90 mol% or more. More preferably, it is 95 mol% or more, particularly preferably 97 mol% or more, and most preferably 99 mol% or more.

Further, the polyester in the present invention may contain other third component within a range not departing from such a range. As the dicarboxylic acid component, in addition to the above-mentioned terephthalic acid and 2,6-naphthalenedicarboxylic acid, isophthalic acid, phthalic acid, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, 2-potassium sulfoterephthalic acid, 2,7 -Naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, phenylindanedicarboxylic acid, diphenyletherdicarboxylic acid, oxycarboxylic acid (for example, p-oxyethoxybenzoic acid), etc. it can. As the glycol component, in addition to the above-mentioned ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like can be used, and one or more of these components can be used. it can.
In the polyester film of the present invention, polyethylene naphthalate is particularly preferably used. When polyethylene naphthalate is used, a small amount, for example, 0.5 to 5.0 mol% of a terephthalic acid component may be contained as an acid component other than naphthalenedicarboxylic acid.
These third components may be contained in the polyester as a copolymerization component or may be a blend.

  When used as a transfer film for injection molding processing with an injection resin temperature of 180 ° C. to 230 ° C., a film mainly composed of polyethylene naphthalate is more heat resistant than polyethylene terephthalate film in such a high temperature region. It is excellent and it is difficult to cause fusion to a resin molded product.

Preferred examples of the catalyst used for the transesterification reaction and polycondensation reaction of polyester include titanium compounds (Ti compounds) and germanium compounds (Ge compounds).
The polyester may be one in which a part or all of the terminal hydroxyl groups and / or carboxyl groups are blocked with a partially functional compound such as benzoic acid or methoxypolyalkylene glycol, or glycerin, pentaerythritol, It may be a copolymer of trifunctional or higher functional components such as merit acid and pyromellitic acid in a minute amount (a range in which a substantially linear polymer is obtained).

The intrinsic viscosity of the polyester in the present invention is preferably 0.48 dl / g to 0.95 dl / g, and more preferably 0.50 dl / g to 0.90 dl / g. When the intrinsic viscosity of the polyester before film formation is in this range, a polyester film having an intrinsic viscosity of 0.45 dl / g to 0.90 dl / g can be obtained. Further, the intrinsic viscosity of the film is preferably 0.48 dl / g to 0.85 dl / g.
When the intrinsic viscosity of the polyester after film formation is in such a range, mechanical properties that can withstand injection molding can be provided when used as an in-mold transfer foil film.
Here, as a method for measuring the intrinsic viscosity, 0.6 g of a sample was dissolved by heating in 50 ml of orthochlorophenol, then cooled once, and the solution was measured from the solution viscosity measured at 35 ° C. using an Ostwald type viscosity tube. It can be calculated and measured.

  The polyester film of the present invention is biaxial in the film longitudinal direction (hereinafter sometimes referred to as film continuous film-forming direction, longitudinal direction and MD direction) and in the lateral direction (hereinafter sometimes referred to as width direction and TD direction). It is a biaxially oriented polyester film obtained by stretching. By being biaxially oriented, a film having high mechanical properties such as Young's modulus and high heat resistance can be obtained.

  Furthermore, the biaxially oriented polyester film of the present invention may contain organic or inorganic particles as a lubricant as necessary in order to improve film winding property during film formation, film transportability, and the like. . Examples of such particles include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, urea resin particles, melamine resin particles, and crosslinked silicone resin particles. Moreover, you may color in white, black, and another color from a designable viewpoint.

[Heat shrinkage]
The biaxially oriented polyester film of the present invention has a heat shrinkage rate of 8% or more, more preferably 10% or more in both the vertical and horizontal directions when heat treated at 180 ° C. for 30 minutes. If the heat shrinkage rate at 180 ° C. is less than the lower limit value, the transfer foil does not sufficiently shrink in the high temperature region near the injection resin temperature, and at the time of in-mold transfer molding using a resin having a high molding temperature as the resin for injection molding Shrinkage spots, wrinkles, etc. occur in the transfer foil, and the shape is transferred to the resin molded product, making it difficult to stably obtain the beautiful appearance of the resin molded product. The heat shrinkage rate at 180 ° C. is preferably larger within such a range, but when the heat shrinkage rate characteristic at 155 ° C. described later is also provided, the upper limit value is preferably 50% or less, It is preferably 30% or less, and may be 20% or less depending on the target shape of in-mold molding.
In order to obtain the heat shrinkability of the present invention at 180 ° C. in both of the biaxial directions, a stretching treatment is performed at a stretching ratio within a certain range in both of the biaxial directions, and a heat setting treatment is further performed at a certain temperature range.

  Usually, in order to increase the thermal dimensional stability of the polyester film, heat setting is often performed at a temperature relatively close to the melting point, and the thermal shrinkage rate of the film tends to be reduced by increasing the crystallinity. On the other hand, in the present invention, in order to suppress the occurrence of shrinkage spots and wrinkles on the transfer foil by the method of shrinking the transfer film according to the shape of the molded product at the time of in-mold transfer molding, 130 ° C. to 220 ° C., preferably The heat setting treatment is performed in a temperature range of 140 ° C to 215 ° C.

Further, the stretching is performed at a temperature lower than usual at the time of film formation, specifically 110 ° C. to 150 ° C., preferably 110 ° C. to 140 ° C. in the case of polyethylene naphthalate resin. By stretching at such a temperature, the film can be sufficiently oriented and crystallized.
Further, in order to obtain the heat shrinkability of the present invention in both biaxial directions at 180 ° C., it is necessary to perform a stretching treatment in a certain range of stretching ratio in both biaxial directions. Although the specific stretching ratio varies depending on the heat setting temperature and the like, for example, when the heat setting temperature is 185 ° C., a method of stretching at a ratio of 3.0 times or more in the longitudinal direction and 2.3 times or more in the transverse direction is mentioned. In the case where the heat setting temperature is 210 ° C., there is a method of stretching at a magnification of 3.6 times or more in the longitudinal direction and 2.5 times or more in the transverse direction.
Furthermore, by reducing the temperature of the preheating step before the transverse stretching within the range of 80 ° C. to 115 ° C. and lower than the transverse stretching temperature, the heat shrinkability in the transverse direction is reduced without reducing the longitudinal heat shrinkability. It is easy to obtain high heat shrinkability in both the vertical and horizontal directions.

In the polyester film of the present invention, the difference in heat shrinkage between the vertical direction and the horizontal direction at 180 ° C. is preferably 10% or less, more preferably 5% or less.
If the difference in thermal shrinkage exceeds the upper limit, shrinkage spots may occur partially at high temperatures during transfer foil processing, and transfer to a resin molded product during in-mold molding may cause poor appearance. There is.

  The biaxially oriented polyester film of the present invention has a heat shrinkage rate of not more than 5% in both the vertical direction and the horizontal direction when heat-treated at 155 ° C. for 30 minutes in addition to the above-mentioned heat shrinkage rate characteristic at 180 ° C. Preferably, it is further 3% or less. If the thermal shrinkage in the vertical and horizontal directions at 155 ° C. exceeds the upper limit, the film shrinks even in the process of raising the film temperature due to the heat of the molten resin injected into the mold, causing shrinkage spots and wrinkles. May occur, and they may be transferred to cause poor appearance of the resin molded product. Moreover, since the processing of the coating layer in the transfer foil processing is generally performed at a temperature of about 150 ° C., the lower one is preferable as long as the heat shrinkage rate at 155 ° C. is applied.

  Thus, in order to reduce the thermal shrinkage rate at 155 ° C. and increase the thermal shrinkage rate at 180 ° C. at relatively close temperatures of 155 ° C. and 180 ° C., the stretching temperature and heat during film formation It is important to perform each of the fixing temperatures within a specific range, and among the above achievement means, it is preferable to perform stretching at a stretching temperature in the range of 110 ° C to 150 ° C, and more preferably in the range of 110 ° C to 140 ° C. The temperature at which the heat setting treatment is performed is preferably 185 ° C to 220 ° C, more preferably 185 ° C to 215 ° C. When the heat setting temperature is lower than the lower limit, thermal shrinkage tends to increase at 155 ° C., and the appearance defect of the resin molded product due to shrinkage in the process of increasing the film temperature may occur. The upper limit of the heat setting temperature is limited by the relationship with the heat shrinkage characteristics at 180 ° C.

[Film thickness]
The thickness of the biaxially oriented polyester film for in-mold transfer of the present invention is 25 μm or more and 200 μm or less, preferably in the range of 50 μm to 188 μm. If the film thickness is less than the lower limit value, a high temperature resin is injected at a high speed or high pressure during in-mold molding using a resin with a high molding temperature as a resin for injection molding. Affects the appearance of the product. On the other hand, if the thickness exceeds the upper limit, the molding processability along the shape of the resin molded product is lowered.

[Film break strength]
The longitudinal breaking strength of the biaxially oriented polyester film in the present invention is preferably 280 MPa or more, more preferably 300 MPa or more, and further preferably 320 MPa or more. Moreover, it is preferable that the breaking strength of a horizontal direction is 200 MP or more, More preferably, it is 230 MPa or more. Since the film of the present invention has such a breaking strength, even when a high-temperature injection resin contacts the film at a high pressure, the film is hardly broken.
A higher breaking strength is preferable, but if either one of the breaking strengths is relatively high, wrinkles may occur in one direction, and therefore the difference in longitudinal and lateral breaking strength is preferably 150 MPa or less.

[5% elongation stress]
The 5% elongation stress in the machine direction and the transverse direction of the biaxially oriented polyester film in the present invention is preferably 110 MPa or more, and more preferably 140 MPa or more. When the 5% elongation stress is lower than the lower limit, the film is not sufficiently oriented during the molding process, and thus shrinkage spots may occur particularly when molding a molded product having a curved surface or unevenness.
In the present invention, in addition to the above-described heat shrinkage characteristics, a method of providing the mechanical strength and deformation stress characteristics of these films includes forming a film at a higher draw ratio among methods for obtaining the heat shrinkage characteristics. .

[Melting subpeak temperature]
The melting sub-peak temperature (Tsm) of the biaxially oriented polyester film in the present invention is preferably 140 ° C. or higher and 210 ° C. or lower, more preferably 170 ° C. or higher and 205 ° C. or lower.
The melting subpeak temperature is a minute endothermic peak that appears before crystal melting by differential scanning calorimetry, and this melting subpeak (Tsm) is observed as a minute peak at a temperature corresponding to the heat fixing temperature of the film. This is because an incomplete portion (pseudocrystal) of the formed crystal structure is melted. When the melting sub-peak temperature is in such a range, the heat shrinkage characteristic of the present invention can be obtained. Moreover, when the melting sub-peak temperature is higher than the lower limit value, film breaking strength characteristics can also be provided.
In order to obtain such a melting subpeak, a heat setting treatment may be performed at a heat setting temperature in the range described in the film forming method.

[Surface orientation coefficient]
The biaxially oriented polyester film of the present invention preferably has a plane orientation coefficient (Ns) of 0.200 or more and 0.280 or less. Here, the plane orientation coefficient (Ns) is a characteristic represented by the following formula (1).
Ns = (nMD + nTD) / 2−nZ (1)
(Where nMD represents the refractive index in the longitudinal direction within the film plane, nTD represents the refractive index in the lateral direction within the film plane, and nZ represents the refractive index in the film thickness direction)
When this plane orientation coefficient (Ns) is less than the lower limit, the thickness unevenness due to insufficient stretching may be large, and sufficient thermal shrinkage of the present invention may not be obtained, or sufficient breaking strength may not be obtained. On the other hand, in order to obtain a plane orientation coefficient (Ns) exceeding the upper limit, the film is stretched at a high magnification and the film may be broken or may be restricted by the relationship with the film forming apparatus.

[Primer layer]
In this invention, it is preferable to provide a primer layer in a polyester film, and it is preferable that a primer layer is formed with the coating liquid which consists of aqueous solution or an aqueous dispersion. Moreover, it is preferable that a primer layer is formed in the side which carries out the transfer foil process on a polyester film at least.
The thickness of a primer layer is 0.001-10 micrometers normally as thickness after drying, Preferably it is 0.010-5 micrometers.

  The main component of the primer layer is at least one resin selected from a polyurethane resin, a polyester resin, an acrylic resin, an acrylic resin-modified polyester resin, and a vinyl resin-modified polyester resin, or a silane coupling agent. preferable. By having the primer layer, adhesion to a layer to be laminated on the polyester film when forming the transfer foil, for example, a layer such as a coating film, a vapor deposition film, a hard coat layer, or a printing layer can be improved. It is also possible to make a substance having an antiblocking and slipperiness imparting effect, a substance exhibiting an antistatic effect, and other substances for imparting various functions easily present on the film surface.

  The primer layer is preferably applied and formed in the film forming process, and is preferably applied to at least one surface of the polyester film before completion of orientation crystallization. Thereby, the uniformity of the primer layer surface and the adhesion of the primer layer to the polyester film can be enhanced. Further, the primer layer forming coating solution is preferably an aqueous solution or an aqueous dispersion containing the above-mentioned main components from the viewpoints of work environment and external environment conservation. Further, as long as the object of the present invention is not impaired, a primer layer may be provided on the film, or corona discharge treatment, plasma treatment, flame treatment, etc. may be performed.

[Film production method]
As a method for producing a biaxially oriented polyester film of the present invention, for example, a sufficiently dried polyester resin composition is melt-extruded at a temperature ranging from the melting point of the resin to (melting point + 70 ° C.), rapidly cooled on a casting drum, and unstretched. Examples thereof include a method of forming a film, and then subjecting the unstretched film to biaxial stretching or simultaneous biaxial stretching in the longitudinal and lateral directions and heat setting.
Biaxial stretching is preferably sequential biaxial stretching. In that case, in the case of polyethylene naphthalate, the unstretched film is stretched in the machine direction at 110 ° C to 150 ° C at 3.0 times or more, preferably 5.5 times or less, Next, the film is stretched in the transverse direction at 110 to 150 ° C. by 2.3 times or more, preferably 4.0 times or less, and then 130 to 220 ° C., more preferably 185 ° C. to 220 ° C., more preferably 185 ° C. Heat-set at a temperature of ˜215 ° C. under tension or limited shrinkage. The heat setting time is preferably 10 to 30 seconds. The heating medium for longitudinal stretching may be set at the roll temperature, or may be heated by installing a heater such as infrared rays above the film.
The temperature of the preheating step in which the temperature is first applied in the stenter is usually 105 ° C to 125 ° C. However, when the film is stretched successively by 4.0 times or more in the machine direction, the temperature of the preheating process in which the temperature is first applied in the stenter is set to 80 ° C. to 115 ° C. and the film is warmed evenly when the film is horizontally stretched. It is preferable because it can be stretched. Also, a lower preheating temperature is preferable because it can be stretched in the horizontal direction without decreasing the vertical orientation, and the decrease in the strength and heat shrinkage in the vertical direction can be suppressed.

In the case of polyethylene terephthalate, in the above production conditions using polyethylene naphthalate, the stretching temperature in the longitudinal direction is 80 to 130 ° C., the stretching temperature in the transverse direction is 80 to 130 ° C., and the heat setting temperature is 130. It is good to carry out at -220 degreeC, More preferably, it is 155-180 degreeC. Similarly, the preheating step after the longitudinal stretching step may be performed in the range of 70 to 100 ° C. A draw ratio can be performed in the same range as polyethylene naphthalate.
In the case of simultaneous biaxial stretching, the stretching temperature, stretching ratio, heat setting temperature, etc. of the sequential biaxial stretching can be applied. If necessary, the biaxially stretched film can be further produced by a so-called three-stage stretching method or four-stage stretching method in which the film is re-stretched in the machine direction and / or the transverse direction. In that case, it is preferable to adjust so that the sum total of the draw ratio of each direction may become said range.

[Transfer foil processing]
Transfer foil processing is continuously formed at a predetermined interval on one side of a biaxially oriented polyester film for in-mold transfer. Specifically, on one side of the polyester film for transfer, a release layer for easily peeling the transfer foil processed layer from the polyester film for transfer, and on that, a hard coat layer, a pattern or a mark for alignment And a bonding layer for improving the adhesion between the resin molded product and the transfer foil processed layer.
A melamine resin or the like is used for the release layer, and printing is performed by a gravure printing method or a screen printing method. In the case of coating and curing, heat curing is often applied at a temperature of about 150 ° C.

The hard coat layer and the design layer are formed of a color ink containing a resin as a binder and a colorant such as a pigment or a dye as necessary. Resins used as binders include polyvinyl resins, polyamide resins, polyester resins, polymethyl methacrylate resins, polyurethane resins, polyvinyl acetal resins, polyester urethane resins, alkyd resins, and the like. As the coating method, printing is performed on the release layer by a gravure printing method, a screen printing method, an offset printing method, or the like. The design layer may be formed by a vacuum deposition method, a sputtering rig method, an ion plating method, or the like.
As the adhesive layer, a material suitable for molding resin can be used as appropriate. For example, an acrylic resin, a polystyrene resin, a polyamide resin, or the like may be used. Various coating methods such as gravure printing and screen printing can be used as the coating method.

[Thermoplastic resin of resin molding]
As the thermoplastic resin for injection molding in the present invention, a thermoplastic resin having high heat resistance is preferable. Polycarbonate resin, polyphenylene ether resin, polyarylate resin, polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, cyclic polyolefin resin And polyetherimide resin, polyamideimide resin, polyimide resin, polyolefin resin, polyester resin, polystyrene resin, acrylic resin, polyamide resin, polyalkylene ether resin, polyurethane resin, and polyaminobismaleimide resin. Any of the above resins may be a copolymer composed of a plurality of structural units, and the copolymer form is also a random copolymer, a graft copolymer, a block copolymer, and a higher order structure. It may be a controlled copolymer structure. Copolymer resins of vinyl monomers represented by styrene are widely used and can be used as the S component of styrene copolymer resins. For example, AS resin (resin mainly composed of acrylonitrile-styrene copolymer), SMA resin (resin mainly composed of styrene-maleic anhydride copolymer), MS resin (resin mainly composed of methyl methacrylate-styrene copolymer) and Examples thereof include ABS resin (resin mainly composed of acrylonitrile-styrene-butadiene copolymer).
Of these, polycarbonate resins are most preferred. The polycarbonate resin may be a polycarbonate resin polymerized using other dihydric phenols in addition to the commonly used bisphenol A type polycarbonate. The resin can contain various conventionally known additives. Examples of such additives include heat stabilizers, antioxidants, ultraviolet absorbers, colorants, and the like.

  The resin material is preferably supplied to an injection molding machine in the form of pellets obtained by melting and kneading necessary additives with a raw material resin, and it is preferable that the water content in the resin is sufficiently reduced at the time of supply. It is preferable that a thermoplastic resin having a high moisture absorption such as a polycarbonate resin is supplied to an injection molding machine after being sufficiently dried. A conventionally known melt kneader can be used for the melt kneading, and a vent type twin screw extruder is particularly suitable.

[Resin molding]
The thickness of the resin molded product in the present invention is preferably in the range of 2 mm to 30 mm, more preferably 3 mm to 30 mm, and even more preferably 5 to 30 mm. If it is thinner than the lower limit, the film may be deformed by shearing of the resin during injection molding. On the other hand, when the thickness is larger than the upper limit, the heat load on the transfer film at the time of injection molding becomes large and the transfer film may be fused.
The resin molded product preferably has a drawing shape on the surface to which the transfer foil processed layer is applied. In the aperture shape, the aperture ratio is 0.07 or more and the area is preferably 3,000 mm ² or more, and the aperture ratio is 0.07 or more and the area is more preferably 30,000 mm ² or more. If the drawing ratio is smaller than the lower limit value, or if the area is smaller than the lower limit value, molding can be performed by the conventional technique. The drawing ratio is represented by “the height of the unevenness / the diameter of the circle equivalent to the projected area” in the transfer foil processed layer application portion.

[Method of manufacturing resin molded product]
The manufacturing method of a resin molded product is given below.
As an example, after placing a biaxially oriented polyester film for in-mold transfer that has undergone transfer foil processing between one mold and the other mold, the mold is clamped to form a molding cavity, A method for producing a resin molded product including a step of injecting a thermoplastic resin into the cavity can be mentioned. The molding cavity refers to a molding space formed by clamping the movable side mold and the fixed side mold.
It is preferable that the molten resin is injected and filled into a molding cavity that is previously opened by an amount corresponding to the compression stroke after being disposed between the one mold and the other. In this injection compression molding, the total amount of the compression stroke and the thickness of the resin plate is preferably in the range of 1.01 to 3 times the target thickness of the resin plate. Final mold clamping is performed after the molten resin is injected into the molding cavity.

As a film placement method of the present invention, a film roll placed above or below the mold is fed while being wound around the other, and a film cut into a sheet is placed in the mold by a robot arm or the like. The method etc. are mentioned.
There is a step of peeling the film from the molded product after molding the resin molded product by the above-described method. As a method of peeling a film from a molded product, when using a film cut into a sheet, a method of peeling manually, a method of peeling with a take-out machine or a robot arm when using a film roll, and For example, there may be mentioned a method of peeling off when the mold is opened by providing a slight undercut part on the other mold of the mold on which the film is arranged.

  The resin molded product manufactured using the method of the present invention has a good appearance even in a shape having a large shape, a thick shape, or a three-dimensional shape. Therefore, resin windows for vehicles, ships, aircraft, etc. that require these characteristics, uses for seeing through images represented by LCD protective materials, and game boards for playground equipment represented by pachinko and pinball. It is useful in a wide range of industrial applications.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. Each characteristic value was measured by the following method.

(1) Film heat shrinkage rate In the longitudinal and lateral directions of a biaxially oriented film, a film with a length of 30 cm square that has been marked by measuring the exact length in advance is unloaded in an oven set at the temperature to be measured. Then, leave it for the required time and take it out.
From the length (L ₀ ) before the heat treatment and the dimensional change (ΔL) due to the heat treatment, the thermal shrinkage rates in the vertical direction and the horizontal direction were obtained according to the following formula (1). The thermal contraction rate in each direction was evaluated with the number of samples n = 5, and the average value was used. This time, the measurement was performed by the above method for two conditions of 155 ° C. for 30 minutes and 180 ° C. for 30 minutes.
Thermal contraction rate (%) = (ΔL / L ₀ ) × 100 (1)

(2) Film Breaking Strength Film breaking strength was measured in a room adjusted to a temperature of 25 ° C. and a humidity of 50% using a tensile tester (trade name “Tensilon” manufactured by Toyo Baldwin). A sample film was cut to a width of 10 mm and a length of 150 mm, a sample was mounted at a chuck distance of 100 mm, a tensile test was performed at a tensile speed of 100 mm / min in accordance with JIS-C2318 5.3.3, and the load elongation curve at break The load was read. The breaking strength was calculated (unit: MPa) by dividing the load at break by the sample cross-sectional area before tension. The longitudinal breaking strength means that the longitudinal direction of the film is the measuring direction, and the transverse breaking strength means that the transverse direction of the film is the measuring direction. Each breaking strength was evaluated with the number of samples n = 10, and the average value was used.

(3) 5% elongation stress A tensile test was performed under the same conditions as the measurement of the breaking strength in (2) above. As the deformation stress, 5% elongation stress at 25 ° C. (stress during elongation) was determined. The stress at 5% elongation was calculated (MPa) by dividing the load at 5% elongation of the load elongation curve by the cross-sectional area of the sample before pulling.

(4) Melting sub-peak temperature (Tsm)
A DSC curve was drawn at a rate of temperature increase of 20 ° C./min using a DSC220 manufactured by Seiko Denshi Kogyo Co., Ltd., and an endothermic peak at a lower temperature side than a clear endothermic peak due to melting was defined as a melting subpeak temperature. In addition, when the melting sub-peak was close to the crystal melting peak and was not clear as a peak, the point where the second derivative curve of the DSC curve was 0 was defined as the sub-peak temperature.

(5) Measurement of plane orientation coefficient of film According to JIS-K7105, nMD, nTD and nZ were measured with an Abbe refractometer (light source: sodium D line 589 nm, mount solution: methylene iodide). The plane orientation coefficient (NS) was obtained from the following equation (1) from the measured nMD, nTD, and nZ.
Ns = (nMD + nTD) / 2−nZ (1)
(Where nMD represents the refractive index in the longitudinal direction within the film plane, nTD represents the refractive index in the lateral direction within the film plane, and nZ represents the refractive index in the film thickness direction)

(6) Film thickness The film sample was measured for 10-point thickness using an electric micrometer (K-402B manufactured by Anritsu), and the average value was defined as the film thickness.

(7) Formability evaluation On one side of the obtained polyester film, the coating liquid consisting of the trade name “TCM01 medium” (manufactured by Dainippon Ink Co., Ltd., melamine resin) is applied to one side of the obtained polyester film so that the thickness after drying becomes 2 μm. And dried at 120 ° C. to form a release layer. Next, the following hard coat layer composition was prepared with a gravure reverse coater, applied so that the thickness after drying was 5 μm, dried at 100 ° C., and then irradiated with ultraviolet rays to cure the hard coat layer. . Next, the following adhesive layer composition was coated with a gravure coater so that the thickness after drying was 0.5 μm, dried at 100 ° C., and a release layer, a hard coat layer, and an adhesive layer were formed on the polyester film. A transfer foil processed film laminated in order was prepared and used for moldability evaluation.
<Hard coat layer composition>
UV curable resin 1 (PETA: Nippon Kayaku Co., Ltd.) 21.3% by weight
UV curable resin 2 (DPHA: Nippon Kayaku Co., Ltd.) 8.6% by weight
-Photocuring initiator (Irgacure 184: Ciba Geigy Co., Ltd.) 2.0% by weight
・ Ethyl acetate 68.1% by weight
<Adhesive layer composition>
・ Polyester resin (P-170: Nippon Synthetic Chemical Co., Ltd.) 20% by weight
Silica particles (average particle size 0.5 μm) 10% by weight
・ Solvent (methyl ethyl ketone: toluene = 1: 1) 70% by weight
Next, using a molding resin (polycarbonate resin [“Panlite L-1225Y” (trade name) manufactured by Teijin Chemicals Ltd.]), a resin molded product was produced according to the following steps. The polycarbonate resin pellets were dried in a hot air dryer at 120 ° C. for 5 hours, and then used as a molding machine using a ULTRAIV injection molding machine manufactured by Sumitomo Heavy Industries with a cylinder diameter of 50 mmφ and a clamping force of 2150 kN, and the mold shown in the right figure of FIG. Injection molding was performed using the transfer foil processed film produced by the above method. Molding was performed at a cylinder temperature of 290 ° C., a hot runner set temperature of 290 ° C., a mold temperature of 100 ° C. on both the fixed side and the movable side, and a cooling time of 30 seconds. The transfer foil processed film was a sheet, and was attached to the fixed or movable parting surface using a double-sided tape, and the transfer foil processed film was arranged so that the adhesive layer side was in contact with the molded resin. Moreover, the film was peeled off from the molded product manually, and the following appearance evaluation was performed.
The molded product has the shape shown in the left figure of FIG. 1, the drawing ratio of the surface to which the transfer foil processed layer is applied is 0.12, the area is 31.416 mm ² , the length is 200 mm, the width is 200 mm, and the thickness is 4 mm. This is a molded product.

(7) -1 Appearance (molded bag)
The presence or absence of wrinkles on the surface of the molded product was observed and evaluated as follows.
(Double-circle): There was no wrinkle and it was a good state, and there was no appearance defect.
○: Some appearance defects were observed with several wrinkles.
X: Appearance defects occurred in a state where countless wrinkles were generated.

(7) -2 Film after molding The state of the film peeled from the molded product was confirmed, and evaluation was performed as follows.
A: The film is not fused to the molded product and the film is not broken.
○: A state in which a part of the film is fused or a part of the film is broken.
X: A state in which the film is melted and fused by the high temperature resin temperature at the time of molding, and the film is also broken.

(8) Transfer foil processability The transfer foil processability of the polyester film was evaluated as follows. A resin paint prepared by using 70% by weight of amino alkyd-based thermosetting resin (base clear: manufactured by Kowa Paint Co., Ltd.) and 30% by weight of thermoplastic urethane resin (X1210 medium: manufactured by Toyo Ink Co., Ltd.) After coating on one side of the polyester film using a gravure coating machine, it was dried and cured in a drying oven at 150 ° C. for 30 minutes to form a cured resin coating film having a thickness of 1.5 μm. The appearance was confirmed and evaluated as follows.
(Double-circle): The external appearance defect was not recognized by the film.
○: Some film shrinkage was observed, but it was possible to perform in-mold molding.
(Triangle | delta): The shrinkage | contraction of a film was remarkable and the external appearance defect produced a film.

Reference Example 1 Production of polyethylene-2,6-naphthalenedicarboxylate (PEN)
100 parts of dimethyl 2,6-naphthalenedicarboxylate and 60 parts of ethylene glycol were used as a transesterification catalyst and 0.03 part of manganese acetate tetrahydrate was used. As a lubricant, calcium carbonate particles having an average particle diameter of 0.5 μm were added to polyethylene-2, 6-Naphthalenedicarboxylate resin composition was added so as to contain 0.25% by weight based on the weight and subjected to a transesterification according to a conventional method, and then 0.042 part of triethylphosphonoacetate was added. Thus, the transesterification reaction was terminated. Next, 0.024 part of antimony trioxide was added, and then the polymerization reaction was carried out in a conventional manner under high temperature and high vacuum, and polyethylene-2,6-naphthalenedicarboxylate (PEN) having an intrinsic viscosity of 0.60 dl / g. Got.

Reference Example 2 Production of polyethylene terephthalate (PET)
A transesterification reaction vessel was charged with 100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol and 0.06 parts by weight of magnesium acetate tetrahydrate, and spherical silica particles having an average particle size of 0.2 μm as a lubricant were polyethylene terephthalate resin composition It was added so as to contain 0.06% by weight based on the weight of the product, heated to 150 ° C., melted and stirred. The reaction was advanced while the temperature in the reaction vessel was slowly raised to 235 ° C., and phenylphosphonic acid was added to complete the transesterification reaction. Thereafter, the reaction product was transferred to a polycondensation apparatus, antimony oxide was added, the temperature in the polymerization apparatus was increased to 290 ° C., and the polymerization reaction was carried out under high vacuum, and a polyethylene terephthalate having an intrinsic viscosity of 0.60 dl / g ( PET) was obtained.

[Example 1]
PEN polymer is dried at 180 ° C for 5 hours, then supplied to an extruder, melted at a melting temperature of 300 ° C, extruded through a die slit, solidified by cooling on a casting drum set at a surface temperature of 55 ° C, and unstretched A film was created. The unstretched film thus obtained is preheated to 130 ° C., and the film is heated to 130 ° C. with a single infrared heater having a surface temperature of 800 ° C. from above 15 mm between the low speed roller and the high speed roller. The film was stretched 4.0 times. Subsequently, the film was supplied to a stenter and the film was warmed at a preheating temperature of 100 ° C., and then stretched 3.0 times in the transverse direction at 130 ° C. The obtained biaxially oriented film was heat-fixed at a temperature of 185 ° C. for 30 seconds to obtain a biaxially oriented polyester film having a thickness of 100 μm. The properties and moldability evaluation of the obtained film were evaluated by the above methods, and the results are shown in Table 1.

[Examples 2 to 9]
In Example 1, a biaxially oriented polyester film was obtained in the same manner as in Example 1 except that the draw ratio, the heat setting temperature, and the film thickness were changed. The characteristics and moldability evaluation of the obtained film were evaluated by the methods described above, and the results are shown in Table 1.

[Example 10]
In Example 1, the PET polymer was dried in a rotary vacuum dryer at 170 ° C. for 3 hours, then supplied to the extruder, melt-extruded at 280 ° C., and formed into a sheet from a die. An unstretched film obtained by cooling and solidifying this sheet with a cooling drum having a surface temperature of 20 ° C. was stretched 3.4 times in the longitudinal direction at 100 ° C., and cooled with a roll group at 25 ° C. Subsequently, the both ends of the longitudinally stretched film were guided to a tenter while being held with clips, and the film was warmed at a preheating temperature of 90 ° C., and then stretched 3.4 times in the transverse direction in an atmosphere heated to 130 ° C. . Thereafter, the film was heat-set in an atmosphere heated to 160 ° C. in a tenter for about 20 seconds and cooled to room temperature to obtain a film. The characteristics and moldability evaluation of the obtained film were evaluated by the methods described above, and the results are shown in Table 1.

[Comparative Examples 1-2]
A film was obtained in the same manner as in Example 1 except that the draw ratio, heat setting temperature, and film thickness were changed in Example 1. The characteristics and moldability evaluation of the obtained film were evaluated by the methods described above, and the results are shown in Table 1.

The symbols described in Table 1 will be described below.
PET: Polyethylene terephthalate PEN: Polyethylene naphthalate

  According to the present invention, in-mold transfer suitable for obtaining a resin molded product having a beautiful appearance without causing film tearing or wrinkles during in-mold molding using a resin having a high molding temperature as a resin for injection molding. A substrate film can be provided.

1 movable mold 2 frame block 3 fixed mold (movable mold and frame structure)
4 Film 5 Molding resin 6 Molded product body

Claims (7)

A polyethylene naphthalate, excluding a multilayer film, having a heat shrinkage rate of 8% or more in both the vertical and horizontal directions when heat-treated at 180 ° C. for 30 minutes, and having a film thickness of 25 μm or more and 200 μm or less. A biaxially oriented polyester film for in-mold transfer as a main constituent .   The biaxially oriented polyester film for in-mold transfer according to claim 1, wherein the breaking strength in the longitudinal direction of the film is 280 MPa or more, the breaking strength in the transverse direction is 200 MPa or more, and the 5% elongation stress of the film in both directions is 110 MPa or more.   The biaxially oriented polyester film for in-mold transfer according to claim 1 or 2, wherein a melting subpeak temperature (Tsm) of the film is 140 ° C or higher and 210 ° C or lower.   The biaxially oriented polyester film for in-mold transfer according to any one of claims 1 to 3, wherein the film has a plane orientation coefficient of 0.200 or more and 0.280 or less. And the thermal shrinkage difference between the vertical and horizontal directions is 10% or less at 180 ° C., and 155 ° C., according to claim 1-4 thermal shrinkage upon heat treatment for 30 minutes is 5% or less in both longitudinal and transverse directions The biaxially oriented polyester film for in-mold transfer according to any one of the above. 2. A primer layer is formed on at least the transfer foil processing side of the film, and the primer layer is applied in the process of forming a polyester film containing polyethylene naphthalate as a main constituent. The biaxially oriented polyester film for in-mold transfer according to any one of 5 to 5 . In-mold transfer foil comprising in-mold transfer biaxially oriented polyester film according to any one of claims 1-6.

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