JP4886247B2 - Multilayer laminated film - Google Patents

Description

  The present invention relates to a multilayer laminated film substantially free of heavy metal elements, which has a design property by color development, and which suppresses uneven color and die stripes.

  The multilayer laminated film is obtained by alternately laminating a plurality of layers having a low refractive index and a layer having a high refractive index, and is an optical interference film that selectively reflects or transmits light of a specific wavelength by structural optical interference between the layers. be able to. Such a multilayer laminated film can be made into a pearly luster film that is excellent in design, for example, looks like iridescent, due to structural color development, if the wavelength of light that is selectively reflected or transmitted is in the visible light region. Moreover, the design property obtained here is due to the structural color development of the multilayer laminated film, so that there is no problem of fading unlike the color development with dyes. In addition, such a multilayer laminated film can obtain a high reflectivity equivalent to a film using metal by gradually changing the layer thickness or by laminating multilayer laminated films having different reflection peaks. It can also be used as a metallic gloss film or a reflection mirror.

As these multilayer laminated films, a multilayer laminated film using thermoplastic resins of different materials such as polyethylene terephthalate and polymethyl methacrylate has been proposed in JP-A-56-99307 and the like. Further, in Japanese Patent Publication No. 9-506837 and International Publication No. 01/47711 pamphlet, a multilayer stretched film using a polyethylene 2,6-naphthalenedicarboxylate layer as a high refractive index layer is proposed.
These multilayer laminated films can be made into a fine powder of 5 mm square or less by a known processing method (for example, guillotine processing or the like). Japanese Laid-Open Patent Publication No. 58-159404 proposes the use of a fine powder of a multilayer laminated film for cosmetics.

JP-A-56-99307 Japanese National Patent Publication No. 9-506837 International Publication No. 01/47711 Pamphlet JP 58-159404 A

  Such a multilayer laminated film generally contains a small amount of a heavy metal element such as an antimony element as a catalyst, and when used in a cosmetic, it is necessary to perform a treatment for removing the heavy metal. In addition, since such multilayer laminated films combine polymers having different compositions in order to increase the difference in refractive index between layers, the adhesion between the layers is weak and the delamination phenomenon tends to occur. Further, since resins having different compositions are combined, it is difficult to uniformly stretch the film, and uneven color and die streaks are likely to occur, or the film tends to tear easily with insufficient strength. The object of the present invention is to solve the problems of the prior art, have the design by the structural color development of the multilayer laminated film, substantially contain no heavy metal element, have high adhesion between layers, and have uneven color. An object of the present invention is to provide a multilayer laminated film in which die lines are suppressed and the film itself is difficult to tear.

That is, the present invention provides a biaxial structure in which a first layer of crystalline thermoplastic resin and a second layer of crystalline thermoplastic resin different from the first layer are alternately laminated in a total number of 11 layers or more. A laminated film that has been stretched,
The crystalline thermoplastic resin constituting the first layer is polyethylene-2,6-naphthalene dicarboxylate having a melting point of 260 to 270 ° C., and the crystalline thermoplastic resin constituting the second layer is isophthalic acid copolymer polyethylene-2. , 6-naphthalenedicarboxylate or terephthalic acid copolymerized polyethylene-2,6-naphthalenedicarboxylate,
Each layer has a thickness of 0.05 to 0.5 μm, and the base line obtained from the light reflectance curve in the range of the wavelength of 350 to 2000 nm of the maximum light reflectance of the laminated film in the wavelength range of 350 to 2000 nm The amount of heavy metal elements contained in the laminated film is 20 ppm or less, the amount of arsenic element is 2 ppm or less, the film thickness fluctuation rate is less than 5%, and the crystallization peak is 150 ° C. to 220 °. It is a multilayer laminated film for cosmetics characterized by existing in the range of ° C.

  According to the present invention, the multi-layer laminated film has a design property due to structural color development, does not substantially contain heavy metal elements, has high adhesion between layers, suppresses uneven color and die streaks, and tears the film itself. It is difficult to provide a multilayer laminated film.

Hereinafter, the present invention will be described in detail.
[Crystalline thermoplastic resin]
In the present invention, a crystalline thermoplastic resin is used for the first layer, and a crystalline thermoplastic resin different from the first layer, particularly a crystalline thermoplastic resin having a different melting point is used for the second layer. And after extending | stretching and orientating a film, only one side of a crystalline thermoplastic resin is fuse | melted and a refractive index difference is provided.

As the crystalline thermoplastic resin used for the first layer and the second layer, it is preferable to use a combination of resins having a difference in melting point measured by differential scanning calorimetry of 5 ° C. or more.
As preferred combinations of the crystalline thermoplastic resins used for the first layer and the second layer, for example, a combination of polyethylene terephthalate and isophthalic acid copolymerized polyethylene terephthalate, polyethylene terephthalate and 2,6-naphthalenedicarboxylic acid copolymerized polyethylene terephthalate A combination of polyethylene-2,6-naphthalene dicarboxylate and isophthalic acid copolymer polyethylene-2,6-naphthalene dicarboxylate, a polyethylene-2,6-naphthalene dicarboxylate and terephthalic acid copolymer polyethylene terephthalate A combination of crystalline nylon MXD6 and crystalline nylon 6, a combination of crystalline nylon MXD6 and crystalline nylon 6 copolymer MXD6, polyethylene terf Combination of rate and crystalline polylactic acid, a combination of polyethylene-2,6-naphthalene dicarboxylate and the crystalline polylactic acid, can be employed.

  In the present invention, a crystalline thermoplastic resin is used for both the first layer and the second layer, but if one or both layers are amorphous resins (for example, described in JP-A-56-99307). A combination of polyethylene terephthalate and polymethacrylate that has been used, and heat which is amorphous with polyethylene 2,6-naphthalenedicarboxylate described in JP-A-9-506837 and WO 01/47711 A combination of a plastic elastomer, a combination of polyethylene 2,6-naphthalene dicarboxylate and 30 mol% PEN copolymerized with amorphous isophthalic acid) has a sufficient refractive index difference and interlayer adhesion. Cannot be granted.

[Heavy metal content]
In the multilayer laminated film of the present invention, the amount of heavy metal element contained in the film is 20 ppm or less, and the amount of arsenic element is 2 ppm or less. When the heavy metal element exceeds 20 ppm or the arsenic element content exceeds 2 ppm, the use of the multilayer laminated film is limited, and for example, it cannot be used as a cosmetic that is an important application of the present invention. As a method for detecting heavy metal elements and arsenic elements, a method using a colorimetric reagent or a microwave decomposition-ICP method described in the cosmetic composition standard is used.

  As the thermoplastic resin constituting the multilayer laminated film of the present invention, it is preferable to use polyester because a refractive index difference can be efficiently expressed by biaxial stretching and subsequent heat treatment. From the viewpoint of ensuring safety when used as a cosmetic, it is preferable to use a polyester containing no heavy metal element, particularly a polyester containing no antimony element, as the polyester. “Not containing antimony element” means that the content of antimony element is, for example, 10 ppm or less, preferably 5 ppm or less. For this purpose, it is necessary to polymerize the polyester using a catalyst containing no heavy metal element, particularly a catalyst containing no antimony element. Therefore, for the polymerization of polyester, (i) a titanium compound is used as the transesterification catalyst and a germanium compound is used as the polycondensation reaction catalyst, or (b) a titanium compound is used as the transesterification catalyst and the polymerization reaction catalyst. In addition, (c) a titanium compound may be used as a catalyst in the esterification method.

  In the case of (i), the titanium compound used as the catalyst is preferably titanium tetrabutoxide or titanium acetate. The amount of the titanium compound used as the catalyst is such that the titanium element concentration remaining in the polyester is preferably 10 to 400 ppm, more preferably 10 to 150 ppm.

  That is, the polyester used as the crystalline thermoplastic resin is preferably produced using a titanium compound as a transesterification catalyst and a germanium compound as a polycondensation reaction catalyst, and preferably contains 10 to 400 ppm of titanium element and germanium element. As the germanium compound used as a catalyst, germanium oxide is preferable, amorphous germanium oxide, fine crystalline germanium oxide, a solution in which germanium oxide is dissolved in glycol in the presence of an alkali metal or an alkaline earth metal or a compound thereof, germanium oxide Is preferably used as a solution in water. The amount of the germanium compound used as the catalyst is preferably 60 to 300 ppm, more preferably 100 to 200 ppm as the concentration of germanium element remaining in the polyester.

  In the case of (b), an organic titanium compound soluble in polyester is preferably used. Specific examples include titanium tetrabutoxide, titanium trimellitic acid titanium, tetraethoxy titanium, titanium sulfate, and titanium chloride. Of these, titanium tetrabutoxide and titanium trimellitic acid are preferable.

  In the case of (b), the catalyst titanium compound may be added at any time before the start of the transesterification reaction, during the transesterification reaction, after the end of the transesterification reaction, and immediately before the polycondensation reaction. In the esterification method (c), the catalyst titanium compound may be added after the esterification reaction is completed, or may be added immediately before the polycondensation reaction.

  In any method, the titanium compound of the catalyst is preferably used so that the concentration of titanium element contained in the polyester is in the range of 5 to 20 ppm. If it is less than 5 ppm, the productivity at the time of producing the polyester is delayed, and if it exceeds 20 ppm, the heat resistance deterioration of the polymer required at the time of film formation cannot be obtained, which is not preferable.

[Combination of crystalline thermoplastic resins]
As a preferable combination of the crystalline thermoplastic resins used for the first layer and the second layer,
1) A combination of polyethylene terephthalate and isophthalic acid copolymerized polyethylene terephthalate,
2) A combination of polyethylene terephthalate and 2,6-naphthalenedicarboxylic acid copolymerized polyethylene terephthalate,
3) A combination of polyethylene-2,6-naphthalene dicarboxylate and isophthalic acid copolymerized polyethylene-2,6-naphthalene dicarboxylate,
4) A combination of polyethylene-2,6-naphthalene dicarboxylate and terephthalic acid copolymer polyethylene-2,6-naphthalene dicarboxylate,
Should be adopted.

[Polyethylene terephthalate]
First, the cases of 1) and 2) using polyethylene terephthalate and its copolymer will be described.
The polyethylene terephthalate constituting the first layer may be copolymerized with some copolymerization components, but the second layer described later has a melting point of 250 to 260 ° C., particularly 250 to 256 ° C. This is preferable because the difference in melting point with the crystalline thermoplastic resin can be made relatively large. The copolymerization component that can be used to obtain such a melting point is at most 10 mol%, and the melting point can be adjusted by appropriately selecting the amount of the copolymerization component. If the melting point of the resin constituting the first layer is less than 250 ° C., the melting point difference from the resin constituting the second layer is small, and it is difficult to impart a sufficient refractive index difference to the resulting multilayer laminated film. It is not preferable. The melting point of polyethylene terephthalate that does not contain a copolymer component is usually around 256 ° C.

  The melting point of the resin constituting the second layer is preferably in the range of 200 to 245 ° C. from the viewpoint of making a difference from the melting point of the resin constituting the first layer. When the melting point of the resin constituting the second layer exceeds 245 ° C., the melting point difference from the resin constituting the first layer becomes small, making it difficult to impart a sufficient refractive index difference to the resulting multilayer stretched film. It is not preferable. When the melting point of the resin constituting the second layer is less than 200 ° C., in order to obtain such a low melting point, it is necessary to copolymerize a large amount of copolymerization components. Since it becomes difficult to provide sufficient adhesion between layers, it is not preferable. From the viewpoint of obtaining a melting point difference from the first layer and suppressing delamination, it is preferable that 75 to 97 mol% of the copolymerized polyethylene terephthalate constituting the second layer is a polyethylene terephthalate unit.

  It should be noted that the proportion of ethylene terephthalate units in the polyester constituting the first layer and the second layer of the multilayer laminated film of the present invention is 80 mol% or more based on the total repeating units of the polyester. To preferred. And it is preferable that 1.5-20 mol% of all the repeating units of all the polyesters of the 1st layer of a multilayer laminated film and a 2nd layer are 2, 6- naphthalene dicarboxylic acid or an isophthalic acid component. If it is less than 1.5 mol%, a sufficient difference in refractive index cannot be obtained from the other layer, and this is not preferred, and if it exceeds 20 mol%, the adhesion between the layers tends to decrease, which is not preferred.

  In the case of 1) and 2) using polyethylene terephthalate and its copolymer, the multilayer laminated film has at least two melting points measured by differential scanning calorimetry, and the difference between the melting points is preferably 5 ° C. or more. The crystallization peak measured by differential scanning calorimetry is preferably at 100 to 190 ° C.

[Polyethylene-2,6-naphthalenedicarboxylate type]
Next, the case of 3) and 4) using polyethylene-2,6-naphthalenedicarboxylate and its copolymer will be described.

  The polyethylene-2,6-naphthalene dicarboxylate constituting the first layer may be copolymerized with some copolymerization components, but has a melting point of 260 to 270 ° C., particularly 260 to 267 ° C. However, it is preferable because the difference in melting point with the crystalline thermoplastic resin of the second layer described later can be made relatively large. The copolymerization component that can be used to obtain such a melting point is at most 10 mol%, and the melting point can be adjusted by appropriately selecting the amount of the copolymerization component. If the melting point is less than 260 ° C., the difference in melting point from the resin constituting the second layer becomes small, and it becomes difficult to give a sufficient refractive index difference to the obtained multilayer laminated film, which is not preferable. In addition, the polyethylene-2,6-naphthalenedicarboxylate melting point not containing a copolymer component is usually around 267 ° C.

  The melting point of the resin constituting the second layer is preferably in the range of 215 to 255 ° C. from the viewpoint of making a difference from the melting point of the resin constituting the first layer. When the melting point of the resin constituting the second layer exceeds 255 ° C., the melting point difference from the resin constituting the first layer becomes small, making it difficult to give a sufficient refractive index difference to the resulting multilayer laminated film. Become. When the melting point of the resin constituting the second layer is less than 215 ° C., it is necessary to copolymerize a large amount of copolymerization components in order to obtain such a low melting point, and sufficient layers are obtained for the resulting multilayer laminated film. It is not preferable because it becomes difficult to impart the adhesion. From the viewpoint of obtaining a difference in melting point from the first layer and suppressing delamination, 75 to 97 mol% of the copolymerized polyethylene-2,6-naphthalenedicarboxylate constituting the second layer is ethylene-2,6- Naphthalene dicarboxylate units are preferred.

  In this case, the ratio of the ethylene-2,6-naphthalenedicarboxylate unit in the polyester constituting the first layer and the second layer of the multilayer laminated film is 80 mol% or more based on the total repeating units of the polyester. It is preferable from the viewpoint of strength. And it is preferable that 1.5-20 mol% of all the repeating units of all the polyesters of the 1st layer of a multilayer laminated film and a 2nd layer are a terephthalic acid or an isophthalic acid component. If it is less than 1.5 mol%, a sufficient difference in refractive index cannot be obtained from the other layer, and this is not preferred, and if it exceeds 20 mol%, the adhesion between the layers tends to decrease, which is not preferred.

  In the case of 3) and 4) using polyethylene-2,6-naphthalenedicarboxylate and its copolymer, the multilayer laminated film has at least two melting points measured by differential scanning calorimetry, and the difference in melting points Is preferably 5 ° C. or higher, and the crystallization peak measured by differential scanning calorimetry is preferably 150 to 220 ° C.

[Layer thickness]
The thicknesses of the first layer and the second layer are both 0.05 to 0.5 μm. If the thickness is less than 0.05 μm or exceeds 0.5 μm, the maximum reflectance required in the present invention cannot be obtained.

[Maximum reflectance]
The maximum reflectance of light in the wavelength range of 350 to 2000 nm of the multilayer laminated film of the present invention is 20% or more higher than the reflectance of the baseline obtained from the light reflectance curve in the wavelength range of 350 to 2000 nm. This reflectance is achieved by taking the multilayer laminated structure of the present invention and taking the above layer thickness. If it is less than 20%, the design properties due to structural color development of the multilayer laminated film cannot be sufficiently exhibited.

[Breaking strength]
The multilayer laminated film of the present invention is preferably biaxially stretched from the viewpoint of having sufficient mechanical strength. By biaxial stretching, the breaking strength in the film forming direction and the width direction of the multilayer laminated film can be 50 MPa or more, preferably 100 MPa, more preferably 150 MPa or more, particularly preferably 200 MPa or more, and sufficient strength. Can be obtained. When the breaking strength is less than 50 MPa, the handling property at the time of processing the multilayer laminated film is lowered, and the durability when it is made into a product is lowered, which is not preferable. The upper limit of the breaking strength is preferably at most 500 MPa from the viewpoint of maintaining the stability of the stretching process.
Further, the breaking strength ratio in the longitudinal direction and the transverse direction is preferably 2 or less, more preferably 3 or less, and if within this range, sufficient tear resistance can be imparted.

[Crystallization peak]
In the multilayer laminated film of the present invention, the resin constituting the first layer and the second layer is at least partially melted after stretching from the viewpoint of ensuring the adhesion between layers and the film forming property of biaxial stretching. It is preferable that The multilayer laminated film thus obtained has two or more melting points measured by a differential scanning calorimetry (DSC) apparatus, and these melting points are preferably different by 5 ° C. or more.

  In 1) and 2) using polyethylene terephthalate and its copolymer, the second layer is at least partially melted after stretching and the crystallization peak measured by DSC apparatus is in the range of 100 ° C. to 190 ° C. It is preferable. When the crystallization peak is less than 100 ° C, one layer crystallizes rapidly when the film is stretched, the film-forming property at the time of film formation is likely to deteriorate, and the uniformity of the film quality is likely to decrease, such as color spots May occur, which is not preferable. When the crystallization peak exceeds 190 ° C., crystallization occurs at the same time when the second layer is melted by heat setting treatment, and it is difficult to express a sufficient refractive index difference.

  For polyethylene-2,6-naphthalenedicarboxylate and its copolymers 3) and 4), after stretching, the second layer is at least partially melted and has a crystallization peak of 150 measured by DSC apparatus. It is preferable that it exists in the range of ° C to 220 ° C. When the crystallization peak is less than 150 ° C., one of the layers rapidly crystallizes when the film is stretched, so that the film-forming property at the time of film formation is reduced, or the homogeneity of the film quality is likely to be reduced. It is not preferable because hue spots may occur. On the other hand, when the crystallization peak exceeds 220 ° C., crystallization occurs at the same time when the second layer is melted by heat setting, and it is difficult to express a sufficient refractive index difference, which is not preferable.

  The multilayer laminated film of the present invention is obtained by multilayerly laminating and stretching the first layer resin and the second layer resin, both of which exhibit crystallinity, and a uniform film quality multilayer laminated film is obtained, and the stretching step Thereafter, the second layer is melted to improve the interlayer adhesion and simultaneously improve the reflection performance.

[Thermal dimensional stability]
The multilayer laminated film of the present invention has high thermal dimensional stability in the case of 1) and 2) using polyethylene terephthalate and its copolymer. The heat shrinkage rate when treated at 150 ° C. for 30 minutes in the stretched direction (film forming direction and width direction) is 3.0% or less, preferably 2.5% or less, more preferably 2.0% or less. It can be. Further, the thermal contraction rate in the film forming direction and the width direction when treated at 200 ° C. for 10 minutes can be 5.0% or less, preferably 4.0% or less, and more preferably 3.0% or less. . Since it has such high thermal dimensional stability, the multilayer laminated film of the present invention is excellent in process suitability such as bonding with a PVC sheet and embossing.

  In the case of 3) and 4) using polyethylene-2,6-naphthalene dicarboxylate and its copolymer, the multilayer laminated film of the present invention has higher thermal dimensional stability than in the cases of 1) and 2) above. Have sex. The heat shrinkage rate when treated at 150 ° C. for 30 minutes in the stretched direction (film forming direction and width direction) is 2.0% or less, preferably 1.5% or less, more preferably 1.0% or less. It can be. Further, the heat shrinkage rate in the film forming direction and the width direction when treated at 200 ° C. for 10 minutes is 3.0% or less, preferably 2.0% or less, and more preferably 1.5% or less. it can. In this case, in particular, it is possible to sufficiently cope with processing at a high temperature of 160 ° C. or higher in the processing process.

[Thickness fluctuation rate]
In the present invention, the resins constituting the first layer and the second layer are both crystalline resins, and therefore, processing such as stretching is unlikely to be non-uniform, and the thickness unevenness of the film can be reduced. .
The thickness unevenness of the multilayer laminated film of the present invention is less than 10%, preferably less than 5%, as a variation rate of the film thickness represented by the following formula within a range in consideration of the area capable of optical influence. More preferably, less than 3% can be achieved. If the variation rate of the film thickness exceeds 10%, the color of the reflected light changes and appears as color spots, which is not preferable.
Variation rate of thickness = ((T _max −T _min ) / T _ave ) × 100
Here, T _ave represents an average thickness, T _max represents a maximum thickness, and T _min represents a minimum thickness.

[Inert particles]
The multilayer laminated film of the present invention preferably contains inert particles in at least one of the first layer and the second layer in order to improve the rollability of the film. The average particle size of the inert particles is preferably 0.01 to 2 μm, more preferably 0.05 to 1 μm, and particularly preferably 0.1 to 0.3 μm. The content of the inert particles is preferably 0.001 to 0.5% by weight, more preferably 0.005 to 0.2% by weight, based on the weight of the multilayer laminated film. If the average particle size of the inert particles is smaller or less than this, the effect of improving the winding property of the multilayer laminated film tends to be insufficient, and there is no meaning to add, the average of the inert particles When the particle size is larger than this or the content is larger than this, the deterioration of the optical properties of the multilayer stretched film due to the particles becomes remarkable, which is not preferable.

  Examples of the inert particles include inorganic inert particles such as silica, alumina, calcium carbonate, calcium phosphate, kaolin, and talc, and organic inert particles such as silicone, crosslinked polystyrene, and styrene-divinylbenzene copolymer. Can do.

As the inert particles, it is preferable to use spherical particles (hereinafter sometimes referred to as true spherical particles) in which the ratio of the major axis to the minor axis is preferably 1.2 or less, more preferably 1.1 or less. It is preferable because the properties and optical properties can be maintained at a high level.
The inert particles preferably have a sharp particle size distribution, for example, those having a relative standard deviation of less than 0.3, preferably less than 0.2. Use of particles having a relative standard deviation larger than this is not preferable because the frequency of coarse particles increases and optical defects may occur.

The average particle size, particle size ratio, and relative standard deviation of the inert particles are as follows. First, a metal for imparting conductivity is sputtered very thinly on the particle surface, and is magnified 10,000 to 30,000 times with an electron microscope. From this, the major axis, minor axis, and area equivalent circle diameter are obtained, and then these are applied to the following equation.
Average particle diameter = Sum of equivalent circle diameters of measured particles / Number of measured particles Size ratio = Average long diameter of particles / Average short diameter of particles

[Haze / total light transmittance]
The multilayer laminated film of the present invention can achieve a haze of 10% or less by using the above-mentioned inert particles. If the haze exceeds 10%, the film itself becomes whitish and the gloss is lost.

[Method for producing biaxially stretched multilayer laminated film]
Below, the manufacturing method of the multilayer laminated film of this invention is explained in full detail.
The multilayer laminated film of the present invention is a state in which at least 11 layers of the crystalline thermoplastic resin constituting the first layer and the crystalline thermoplastic resin constituting the second layer are alternately stacked in the molten state To give a multilayer unstretched film. The obtained multilayer unstretched film is stretched in the biaxial direction (direction along the film surface) in the width direction perpendicular to the film forming direction. The stretching temperature is preferably in the range of glass transition temperature (Tg) to Tg + 50 ° C. of the resin of the first layer, and the stretching area ratio is preferably 5 to 50 times.

  The larger the draw ratio, the more the variation in the plane direction in the individual layers of the first layer and the second layer is reduced by thinning by stretching, and the optical interference of the multilayer laminated film becomes more uniform in the plane direction. . As the stretching method, either sequential biaxial stretching or simultaneous biaxial stretching can be employed.

  Thus, the multilayer laminated film obtained by extending | stretching is heat-processed, the orientation of the molecular chain of a 2nd layer is eased, and the refractive index of a 2nd layer is reduced. The temperature of the heat treatment ranges from a temperature 10 ° C. lower than the melting point of the resin of the second layer to a temperature 15 ° C. lower than the melting point of the resin of the first layer, preferably 6 ° C. lower than the melting point of the resin of the second layer. The temperature is 16 ° C. lower than the melting point of the resin of the first layer, more preferably 2 ° C. lower than the melting point of the resin of the second layer, and 18 ° C. lower than the melting point of the resin of the first layer. If the temperature of the heat treatment is lower than this, the effect of reducing the refractive index by relaxing the molecular chain orientation in the second layer becomes insufficient, and a sufficient refractive index difference cannot be imparted to the resulting multilayer laminated film. If the temperature of the heat treatment is higher than this, the orientation of the molecular chains in the first layer is also relaxed, the refractive index is lowered, and a sufficient difference in refractive index cannot be imparted to the resulting multilayer laminated film. The heat treatment time is, for example, 1 to 60 seconds. By appropriately changing the temperature and time of the heat treatment, the refractive index of the second layer can be adjusted without changing the resin composition, and the necessary reflective properties are imparted to the multilayer laminated film of the present invention. can do.

The invention is further described by way of examples.
In addition, the physical property and characteristic in an Example were measured or evaluated by the following method.
(1) Melting point and glass transition point (Tg) of polyester resin
10 mg of a polyester resin sample was sampled, and the melting point was measured using DSC (trade name: DSC2920, manufactured by TA Instruments) at a rate of temperature increase of 20 ° C./min.

(2) Thickness of each layer A sample was cut into a triangle, fixed in an embedded capsule, and then embedded in an epoxy resin. The embedded sample was cut along a film forming direction and a thickness direction with a microtome (ULTRACUT-S, manufacturer: Reihert) to form a thin film slice having a thickness of 50 nm. The obtained thin film slice was observed and photographed at an acceleration voltage of 100 kV using a transmission electron microscope (manufacturer: JEOL Ltd., trade name: JEM2010), and the thickness of each layer was measured from the photograph.

(3) Measurement of melting point and crystallization peak of film by DSC 10 mg of the sample film was sampled, and 20 ° C./min. With DS instrument made by TA Instruments (TA Instruments, trade name: DSC2920). The crystallization temperature and the melting point were measured at a rate of temperature increase.

(4) Reflectance and reflection wavelength Using a spectrophotometer (manufactured by Shimadzu Corporation, MPC-3100), the relative specular reflectance with an aluminum-deposited mirror at each wavelength was measured in the wavelength range of 350 nm to 2000 nm. The maximum reflectance among the measured reflectances was defined as the maximum reflectance, and the wavelength was defined as the maximum reflectance wavelength.

(5) Total light transmittance and haze Total light transmittance T _t (%) and scattered light using a haze measuring device (NDH-20, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K6714-1958 The transmittance T _d (%) was measured, and haze (%) was calculated from the following formula.
Haze (%) = (T _d / T _t ) × 100

(6) Breaking strength The breaking strength in the film forming direction is that the sample film is cut into a sample width (width direction) of 10 mm and a length (film forming direction) of 150 mm, the chuck is 100 mm, the pulling speed is 100 mm / min, and the chart speed is 500 m / min. The sample was pulled with an Instron type universal tensile testing device under the condition of min. Then, the breaking strength was measured from the obtained load-elongation curve.
The breaking strength in the width direction was the same as the measurement of breaking strength in the film forming direction, except that the sample film was cut into a sample width (film forming direction) of 10 mm and a length (width direction) of 150 mm.

(7) Heat shrinkage rate The heat shrinkage rate when treated at 150 ° C. for 30 minutes is such that the film is held in a non-tensioned state in an oven set at 150 ° C. for 30 minutes, and the dimensional change before and after the heat treatment is observed. The heat shrinkage was calculated by the following formula.
Thermal shrinkage% = ((L0−L) / L0) × 100
L0: Distance between gauge points before heat treatment L: Distance between floating points after heat treatment The heat shrinkage rate when treated at 200 ° C. for 10 minutes is 10 minutes in a tension-free oven at 200 ° C. The dimensional change before and after the heat treatment was calculated as the heat shrinkage rate by the above formula.

(8) Thickness variation rate A film sample cut to 1 m × 1 m in the film forming direction and the width direction is cut into 25 pieces each having a width of 2 cm along the vertical direction and the width direction, and the thickness of each sample is measured with an electronic micro Measurement was performed continuously using a meter and a recorder (K-312A, K310B, manufactured by Anritsu Electric Co., Ltd.). The average thickness was calculated from all the measured values, the measured values were further subdivided every 200 mm, the maximum value and the minimum value were read, and the thickness variation rate with respect to the average thickness was calculated by the following formula.
Thickness variation rate (μm) = (T _max −T _min )
Here, T _max in the above formula is the maximum thickness, and T _min is the minimum thickness.

(9) Interlayer adhesion Adhesive tape with a width of 24 mm (made by Nichiban Co., Ltd., trade name: cello tape (registered trademark)) is attached to both surfaces of a sample film (10 mm × 50 mm), peeled off at a peeling angle of 180 degrees, and then peeled off. The surface was observed. This was performed for each 10 samples, and the number of delaminations was calculated.

(10) Hue spots 10 A4 size sample films are prepared, and each sample film is layered on white plain paper. Under the illumination of 30 lux, the visible hue spots in the sample film are visually observed. evaluated. In addition, 10 A4 size sample films were prepared, and the back surface of each sample film was colored with a black spray, and then the reflected color spots in the sample film were visually observed under 30 lux illumination. evaluated. Then, the patches of the hues of the transmitted color and the reflected color were synthesized and judged according to the following evaluation criteria.
◯: There are no visible hue spots in the sample.
(Triangle | delta): The part from which a hue differs partially in a sample is seen.
X: Hue spots that clearly appear as spots or streaks can be confirmed.

(11) Content of heavy metal element and arsenic element The sample film was evaluated as follows according to the purity test of the cosmetic compounding component standard polyethylene terephthalate / polymethyl methacrylate laminated film powder.
Heavy metal elements:
○: Heavy metal element content is 20 ppm or less ×: Heavy metal element content exceeds 20 ppm Δ: Arsenic element that cannot be determined:
○: Arsenic element is 2 ppm or less ×: Arsenic element exceeds 2 ppm Δ: Cannot be determined

(12) Color unevenness evaluation method A sample film having a size of 20 cm square was visually observed.
×: Uneven color is visible △: Uneven color is slightly visible ○: Uneven color is not visible

(13) Evaluation method of die stripe A sample film having a size of 20 cm square was visually observed from a position of 45 ° obliquely at a distance of about 30 cm from the film surface under a halogen lamp.
×: Streaks with different hues can be seen Δ: Streaks with slightly different hues can be seen ○: Streaks with slightly different hues can be seen

[ Reference Example 1]
Polyesters were prepared using the dicarboxylic acid component, copolymer component, polycondensation catalyst and phosphorus compound shown in Table 1. Table 1 shows the types and amounts of metal elements contained in the obtained polyester.
In the table, DMT of the acid component, that is, the dicarboxylic acid component is dimethyl terephthalate, TA is terephthalic acid, IA of the copolymer component is isophthalic acid, DMN is dimethyl 2,6-naphthalenedicarboxylate, and TBT of the polycondensation catalyst is tetra Butyl titanate, TMT is tetramethyl titanate, TEPA of tetramethyl phosphorus compound is tetraethylphosphonoacetic acid, PA is normal phosphoric acid, Ti of metal element of polycondensation catalyst is titanium element, Sb is antimony element, Ge is It is a germanium element and DEG represents a diethylene glycol component contained in the polyester.

  As the polyester constituting the first layer, “PET-1” described in Table 1 is used, and as the polyester constituting the second layer, “IA12PET-1” (inactive particles). “A”, an average particle diameter of 1.5 μm, containing spherical silica particles of 0.1% by weight) was used.

  The polyester for the first layer and the polyester for the second layer are each dried at 170 ° C. for 3 hours, then supplied to an extruder, heated to 280 ° C. to be in a molten state, and the polyester for the first layer is After branching the polyester for 101 layers and the second layer into 100 layers, using a multi-layer feedblock device in which the first layer and the second layer are alternately laminated, the laminated state is maintained. It led to the die | dye, it casted on the casting drum, and the unstretched multilayer laminated | multilayer film of a total of 201 layers by which the 1st layer and the 2nd layer were laminated | stacked alternately so that the thickness of each layer might become equal were produced.

  At this time, the extrusion amount of the polyester of the first layer and the polyester of the second layer was adjusted to be 1: 1, and the both end layers were laminated so as to be the first layer. This multilayer unstretched film was stretched 3.6 times in the film forming direction at a temperature of 90 ° C., further stretched 3.9 times in the width direction at a temperature of 95 ° C., and heat-set at 230 ° C. for 3 seconds. . Table 2 shows the physical properties of the obtained multilayer laminated film.

[ Reference Examples 2 to 4 and Comparative Examples 1 to 4]
A multilayer laminated film was obtained in the same manner as in Example 1 except that the polyester for the first layer and the polyester for the second layer were changed as shown in Table 2. Table 3 shows the physical properties of the obtained multilayer laminated film.

[Examples 1 to 4 and Comparative Examples 5 to 8]
A multilayer laminated film was obtained in the same manner as in Example 1 except that the polyester for the first layer and the polyester for the second layer were changed as shown in Table 4. Physical properties of the multi-obtained layer film shown in Table 5.

  The multilayer laminated film of the present invention is a film that looks iridescent due to the structure of the multilayer laminated film and exhibits pearl luster, and can be suitably used as a cosmetic or a decorative film to be blended in cosmetics.

It is an example of the graph of the reflectance with respect to the wavelength of the light of the multilayer laminated film of this invention.

Explanation of symbols

1 Difference between maximum reflectance and baseline of reflectance 2 Baseline of reflectance

Claims (2)

A laminate in which a first layer of crystalline thermoplastic resin and a second layer of crystalline thermoplastic resin different from the first layer are alternately laminated in a total number of 11 layers and biaxially stretched A film,
The crystalline thermoplastic resin constituting the first layer is polyethylene-2,6-naphthalene dicarboxylate having a melting point of 260 to 270 ° C., and the crystalline thermoplastic resin constituting the second layer is isophthalic acid copolymer polyethylene-2. , 6-naphthalenedicarboxylate or terephthalic acid copolymerized polyethylene-2,6-naphthalenedicarboxylate,
Each layer has a thickness of 0.05 to 0.5 μm, and the base line obtained from the light reflectance curve in the range of the wavelength of 350 to 2000 nm of the maximum light reflectance of the laminated film in the wavelength range of 350 to 2000 nm The amount of heavy metal elements contained in the laminated film is 20 ppm or less, the amount of arsenic element is 2 ppm or less, the film thickness fluctuation rate is less than 5%, and the crystallization peak is 150 ° C. to 220 °. A multilayer laminated film for cosmetics characterized by being in the range of ° C. Crystalline thermoplastic resin of the first layer and the second layer are both made of a polyester containing no antimony element, a multilayer laminated film for cosmetics according to claim 1, wherein.

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