JP6424474B2 - Reflective film, liquid crystal display device comprising the same, lighting device, decorative article - Google Patents

Description

  The present invention relates to a reflective film that reflects light, has a metallic-like gloss, and has high reflectance and specular reflection characteristics.

  Heretofore, as a method of imparting a metallic-like gloss to a reflective surface, a method of highly polishing a metal to form a reflective surface has been used. Since this method has low productivity and there are processing problems in the metal used, in recent years, metal-coated plastic in which plastic is thinly coated with metal is used as a reflective film for display devices, illumination and the like. Usually, methods such as electroplating, vacuum evaporation, vapor deposition, and chemical adsorption are used to coat the metal layer. However, in such a metal coating, since the metal corrodes with the passage of time, a protective layer must be additionally provided on the metal coating layer, which is disadvantageous in terms of productivity and cost.

  Another method is to use a multilayer optical film having a plurality of layers. These metal-glossy reflective films are made to exhibit high reflection characteristics by providing reflection characteristics using the reflection characteristics at the laminated interface and closely controlling the thickness of each layer.

  As a method of using a multilayer optical film having a plurality of layers, reflective polymer bodies containing at least first and second dissimilar polymers have been reported (Patent Documents 1 to 3). These patent documents sufficiently include alternating layers of first and second polymer materials having refractive indices different from each other by 0.03 or more, and the majority amount of each layer is 0.09 μm or less, or 0.45 μm or more. Reflective polymer bodies having an optical thickness have been reported.

Japanese Patent Application Laid-Open No. 03-041401 JP 04-295804 A Unexamined-Japanese-Patent No. 05-193040

  However, in the multilayer optical films disclosed in Patent Documents 1 to 3 above, there is a concern that the manufacturing process becomes complicated and productivity is significantly reduced because uniform multilayer lamination and precise control of the thickness of each layer are required. There is a point.

  That is, an object of the present invention is to provide a reflective film having high reflectance and regular reflection characteristics, having a metallic-like gloss and having high productivity.

  The present inventors, as a factor sufficiently enhancing both high reflectance and regular reflection characteristics, include a regular reflection film (X) having a sea-island structure with a continuous phase (I) and a dispersed phase (II), and a finely powdered filler Clarified that it is important to laminate and integrate a diffusive reflection film (Y) containing the above by coextrusion through an adhesive layer (Z) made of a thermoplastic resin, and complete the present invention .

  That is, the present invention is a diffuse reflection film containing at least two types of thermoplastic resins, a specular reflection film (X) having a sea-island structure with a continuous phase (I) and a dispersed phase (II), and a powdery filler. (Y) is a reflective film laminated and integrated by coextrusion through an adhesive layer (Z) made of a thermoplastic resin, which is an average size (L1) in the flow direction of the dispersed phase (II), And the average dimension (L2) in the width direction is 0.45 μm or more and 100 μm or less, and the average dimension (L3) in the thickness direction of the dispersed phase (II) is 0.01 μm or more and 0.45 μm or less, The reflection characterized in that the average refractive index difference between the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) is 0.05 or more. It is a film.

  Since the reflective film proposed by the present invention does not require uniform multilayer lamination or precise control of the thickness of each layer required for a multilayer optical film having a plurality of conventional layers, it has high productivity and a continuous phase ( I) and a specular reflection film (X) having a sea-island structure by a dispersed phase (II) and a diffuse reflection film (Y) containing a fine powder filler, through an adhesive layer (Z) made of a thermoplastic resin By laminating and integrating by coextrusion, the porous structure of the diffuse reflection film (Y) containing the pseudo multilayer effect of the regular reflection film (X) and the fine powder filler can be simultaneously exhibited, and the high reflectance And specular reflection characteristics, and a reflective film having a metallic-like gloss can be provided.

Hereinafter, a reflective film (referred to as "the present reflective film") as an example of the embodiment of the present invention
Will be explained.

In the present invention, the term “main component” includes the meaning of permitting the inclusion of other components within the range not to interfere with the function of the main component unless specifically stated otherwise. Although the content ratio of the components is not specified, the main component includes the meaning of occupying 50% by mass or more, preferably 70% by mass or more, particularly preferably 90% by mass or more (including 100%) in the composition. It is. When two or more resins constitute the main component, the proportion of each resin in the composition is 10% by mass or more, preferably 20% by mass or more, and particularly preferably 30% by mass or more.
Furthermore, in the present specification, when expressing as “X to Y” (X and Y are arbitrary numbers), “preferably more than X” or “preferably” with the meaning of “X or more and Y or less” unless otherwise stated. Also includes the meaning of “less than Y”.
Furthermore, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), “greater than X is preferable” or “preferably less than Y” Also includes the intention of

<Book reflection film>
The present reflection film is composed of a thermoplastic resin, a regular reflection film (X) having a sea-island structure of a continuous phase (I) and a dispersed phase (II), and a diffuse reflection film (Y) containing a fine powder filler. It is a reflective film laminated and integrated by coextrusion via an adhesive layer (Z).

Generally, when different resins are mixed, their phase states can be roughly divided into (1) complete compatibility (single phase), (2) sea-island structure (polyphase), (3) co-continuous structure (polyphase), ( 4) Divided into four of layered structure (polyphase). Here, (2) the sea-island structure refers to a structure in which one of multiple components is dispersed in a particle-like (island-like) state in a continuous phase. (3) The bicontinuous structure means a structure in which each of a plurality of components forms a continuous phase and mixes with each other. Furthermore, (4) Layered structure means a structure in which the respective components form a continuous phase, but the respective components are independent without mixing with each other.
The sea-island structure in the regular reflection film (X) constituting the present reflection film refers to the above (2). Usually, the island portion, which is the dispersed phase, is discontinuous and shows a minute, substantially spherical structure, but since the island portion in the present reflective film is stretched in the flow direction and width direction, it has a flat elliptical structure Or, a disc-like structure is shown. The presence or absence of such a structure can be confirmed by observing the MD cross section or the TD cross section of the present reflective film with a scanning electron microscope (SEM).

<Regular reflection film (X)>
The thermoplastic resin (A) forming the continuous phase (I) in the regular reflection film (X) and the thermoplastic resin (B) forming the dispersed phase (II) deviate from the range defined in the present invention Unless otherwise specified, the average refractive index difference between the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) is not particularly limited. It is important that is 0.05 or more. By setting the average refractive index difference to 0.05 or more, light is easily reflected at the interface between the continuous phase and the dispersed phase, so that high reflection characteristics can be provided.
For this reason, the average refractive index difference between the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) is at least 0.10. Is more preferably 0.15 or more.
From such a viewpoint, one of the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) is mainly composed of a polyester resin. It is preferable that the other is mainly composed of a fluorine-based resin.

  In addition, the present reflective film is preferably oriented in at least one direction, and there are two directions of flow direction (hereinafter sometimes referred to as MD) and width direction (hereinafter referred to as TD) of the film. More preferably, it is axially oriented. The refractive index of the thermoplastic resin (A) that forms the continuous phase (I) and the thermoplastic resin (B) that forms the dispersed phase (II) by providing orientation to the film by a stretching operation or the like By changing it, it becomes possible to further increase the difference in refractive index between the (A) and the (B). In addition, the average dimension in the flow direction, width direction, and thickness direction of the dispersed phase (II) can be adjusted within the range defined by the present invention, and the film of the present invention can be provided with higher reflection properties. it can.

As a means for orienting the present reflective film in at least one direction to further increase the difference in refractive index, for example, a thermoplastic resin (A) forming the continuous phase (I) and a heat forming the dispersed phase (II) The thermoplastic resin (A) and the thermoplastic resin (B) are selected so that the absolute value of the difference in average refractive index with the plastic resin (B) is greater than 0.05, and the continuous by the stretching The thermoplastic resin (A) forming the phase (I) and / or the thermoplastic resin (B) forming the dispersed phase (II) are oriented to form the thermoplastic resin (A) and the thermoplastic resin (B) The method of adjusting to a preferable range can be mentioned using the difference in birefringence of Examples of the drawing method at this time include drawing methods such as free width uniaxial drawing, constant width uniaxial drawing, tensile drawing method, inter-roll drawing method, roll rolling method and the like.
Also, as another means, the thermoplastic resin (A) forming the continuous phase (I) and / or another heat compatible with the thermoplastic resin (B) forming the dispersed phase (II) The method of adjusting to a preferable range etc. can be mentioned by adding a plastic resin, a refractive index regulator, etc.

Intrinsic birefringence of the thermoplastic resin (A) forming the continuous phase (I) and the dispersed phase (II)
Intrinsic birefringence of the thermoplastic resin (B) to form (1) may be both positive or both negative. Alternatively, either one may be positive and the other negative.
The intrinsic birefringence is the birefringence in which the polymer chain is completely uniaxially oriented, that is, the polymer chain is completely stretched in the uniaxial direction, and the birefringence is parallel to the stretching direction. It is a value obtained by subtracting the refractive index in the direction perpendicular to the stretching direction from the refractive index in the direction. Therefore, a positive intrinsic birefringence means that the refractive index parallel to the stretching direction in uniaxial stretching is larger than the refractive index perpendicular to the stretching direction.
In general, when the intrinsic birefringence is positive, the refractive index in the direction parallel to the stretching direction is higher than the average refractive index. On the other hand, when the intrinsic birefringence is negative, the refractive index in the direction parallel to the stretching direction is smaller than the average refractive index.
In practice, it is difficult to calculate the intrinsic birefringence because it is difficult to completely uniaxially align the polymer chains. However, whether the intrinsic birefringence is positive or negative should be determined by confirming whether the value of birefringence when uniaxially stretched at an appropriate magnification is positive or negative. Can. That is, if the birefringence is positive, it can be determined that the intrinsic birefringence is also positive.

Moreover, the magnitude relationship of the average refractive index between the (A) and the (B), and the (A) and the (B)
It is preferable that the magnitude relationship of the birefringence of That is, assuming that the magnitude relationship of the average refractive index between (A) and (B) is (A)> (B), the magnitude relationship between the birefringences of (A) and (B) is It is preferable that (A)> (B). If the magnitude relationship does not match, it is considered that when the present reflective film is oriented by stretching or the like, a difference in refractive index in the orientation direction of the continuous phase (I) and the dispersed phase (II) hardly occurs.
However, if the main reflective film oriented in at least one uniaxial direction falls within the range defined by the present invention, the agreement between the magnitude relationship between the average refractive index and the birefringence between (A) and (B) is It is not this limitation.

The thermoplastic resin (A) that forms the continuous phase (I) and the thermoplastic resin (B) that forms the dispersed phase (II) may be one type of thermoplastic resin, or two or more types. It may be a mixed resin of thermoplastic resins.
Among them, it is preferable that at least one of the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) is a crystalline thermoplastic resin . A crystalline thermoplastic resin is preferable because the polymer chains are easily oriented, the refractive index difference between the continuous phase (I) and the dispersed phase (II) in the orientation direction is easily increased, and the reflection characteristics are easily improved. In addition, in heat treatment, a crystalline thermoplastic resin is likely to be oriented and crystallized, and is also preferable from the viewpoint of dimensional stability.
In addition, a crystalline thermoplastic resin generally refers to a thermoplastic resin in which a crystal melting peak temperature (melting point) is present, and more specifically, in a differential scanning calorimetry (DSC) performed in accordance with JIS K7121. It is a thermoplastic resin in which the melting point is observed, and includes so-called semi-crystalline state. Conversely, a thermoplastic resin whose melting point is not observed in DSC is referred to as "amorphous".

  The type of such crystalline thermoplastic resin is not particularly limited. For example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene succinate, polybutylene succinate, polylactic acid, poly-ε-caprolactam, etc. Resins, polyethylene resins such as high density polyethylene, low density polyethylene, linear polyethylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester co Polymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate-carbon monoxide copolymer, ethylene-vinyl acetate-vinyl chloride copolymer, ethyne-α-olefin copolymer, etc. The Tylene-based copolymer, polypropylene-based resin, polybutene-based resin, polyamide-based resin, polyoxymethylene-based resin, polymethylpentene-based resin, polyvinyl alcohol-based resin, polytetrafluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene Fluorine-based resins such as resin-based resins, cellulose-based resins, polyether ether ketones, polyether ketones, engineering plastics such as polyphenylene sulfide and polyparaphenylene terephthalamide, and super engineering plastics can be mentioned. Among these, polyester resins are preferable, and crystalline aromatic polyester resins are more preferable.

  Further, at least one of the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) is mainly composed of a polyester resin. Is preferred.

(Polyester resin)
It is preferable that said polyester-based resin is a crystalline thermoplastic resin. In the crystalline polyester-based resin, when stretching is performed, the polymer chain is easily oriented, the refractive index difference between the continuous phase (I) and the dispersed phase (II) in the orientation direction is easily increased, and the reflection characteristic is easily improved. Because it is preferable. In addition, in the heat treatment, it is easy to be oriented and crystallized, which is preferable from the viewpoint of dimensional stability.
In general, polyester resins often have positive intrinsic birefringence, and aromatic polyester resins have high birefringence among them, and therefore refraction of the continuous phase (I) and the dispersed phase (II) with respect to the orientation direction It is preferable because it is easy to increase the rate difference and to improve the reflection characteristic.

Further, one of the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) contains a polyester resin as a main component, It is preferable that the other contains a fluorine-based resin as a main component.
In general, polyester resins, in particular aromatic polyester resins, have a high average refractive index and fluorine resins have a low average refractive index, so it is easy to increase the refractive index difference between the continuous phase (I) and the dispersed phase (II). It is preferable because the characteristics can be easily improved.

The type of polyester resin is not particularly limited. For example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene succinate, polybutylene succinate, polylactic acid, poly-ε-caprolactam, etc. Examples of the resin include.
Among these, crystalline aromatic polyester resins are preferable, and in particular, polyethylene naphthalate resins are preferable from the viewpoint of having a high average refractive index and a high birefringence. Moreover, you may use combining said resin from a viewpoint of adjusting a glass transition temperature (Tg) and a refractive index.
Also, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN)
And mixed resins thereof are also preferred examples. Because PEN and PET are compatible, the Tg and refractive index can be adjusted by mixing PEN with PET.

In the case of using a polyethylene naphthalate resin, the weight average molecular weight of the resin is preferably 30,000 or more, more preferably 40,000 or more, from the viewpoint of impact resistance and film forming property.

  The intrinsic viscosity of the polyester resin is more preferably 0.5 dl / g or more from the viewpoint of film forming properties.

  The range of 70 degreeC-120 degreeC is preferable, and, as for the glass transition temperature (Tg) of the said polyester-based resin, it is more preferable that it is the range of 80 degreeC-120 degreeC. If the glass transition temperature is 70 ° C. or more, the rigidity of the film can be maintained, and if it is 120 ° C. or less, stretching is easy, which is preferable.

  Furthermore, the range of 240 degreeC-270 degreeC is preferable, and, as for melting | fusing point (Tm) of the said polyester-type resin, it is more preferable that it is the range of 250 degreeC-270 degreeC. Sufficient heat resistance can be imparted when the melting point is 240 ° C. or more, and 270 ° C. or less is preferable because it suppresses the thermal decomposition of coexisting thermoplastic resins other than polyethylene naphthalate resins during melt extrusion. .

  When a polyethylene naphthalate resin is used as the polyester resin, it is preferable to use one having a YI value in the range of -10 to 10, particularly in the range of -3 to 3. When the polyethylene naphthalate resin is a mixture, it is preferable that the YI value of each resin is in the range of -10 to 10. If the YI value is in the range of -10 to 10, for example, by incorporating it in a liquid crystal display or the like, the clarity of the image can be further improved, and the luminance improvement rate can be further enhanced.

  A commercial item can also be used as polyethylene naphthalate resin. For example, Theonex TN8065S (a homopolymer of polyethylene naphthalate, manufactured by Teijin Chemicals Ltd., intrinsic viscosity 0.71 dl / g), Theonex TN8065SC (a homopolymer of polyethylene naphthalate, manufactured by Teijin Chemicals, Ltd., an inherent viscosity 0.55 dl / G), Teonex TN 8756 C (copolymer of polyethylene naphthalate and polyethylene terephthalate, manufactured by Teijin Chemicals Ltd., intrinsic viscosity 0.65 dl / g), and the like can be mentioned as preferable examples.

(Fluorinated resin)
On the other hand, the fluorine-based resin preferably has a melting endothermic peak temperature of 130 ° C. or more and 250 ° C. or less.
When the melting endothermic peak temperature of the fluorine-based resin is less than 130 ° C., it is not preferable because surface roughness may occur during kneading and extrusion with the polyester-based resin, and the heat resistance of the reflective film may be reduced. Because of the nature of the reflective film, which is often disposed around the light source, heat resistance is required. Therefore, the melting endothermic peak temperature of the fluorine-based resin is preferably 130 ° C. or more, more preferably 150 ° C. or more, and particularly preferably 180 ° C. or more.
When the melting endothermic peak temperature of the fluorine-based resin exceeds 300 ° C., decomposition of the polyester-based resin is likely to be promoted during kneading and extrusion with the polyester-based resin, which is not preferable because molding becomes difficult. Furthermore, when the melting endothermic peak temperature of the fluorine-based resin is more than 250 ° C. and less than 300 ° C., surface roughening occurs and the morphology of the dispersed phase (II) tends to be coarse, which is not preferable. For this reason, the melting endothermic peak temperature of the fluorine-based resin is preferably 245 ° C. or less, more preferably 240 ° C. or less, and particularly preferably 235 ° C. or less.

  The fluorine-based resin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride-based resin or an ethylene-tetrafluoroethylene-based resin since it has a low average refractive index and excellent stretchability. preferable.

  For example, in the case of using the tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride-based resin or the ethylene-tetrafluoroethylene-based resin, the melting point (Tm) of the fluorine-based resin is 130 for the reason of imparting heat resistance. The range of ° C to 250 ° C is preferable, and the range of 180 ° C to 240 ° C or less is more preferable.

A commercially available product can also be used as tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride resin and ethylene-tetrafluoroethylene resin. For example, Dyneon series (made by 3M), Fluon ETFE, Fluon LM-ETFE, Fluon LM-ETFE AH series (made by Asahi Glass Co., Ltd.), Neoflon ETFE EP series (made by Daikin Industries, Ltd.) etc. can be mentioned as a preferable example.
(Composition of regular reflection film (X))
The mixing mass ratio of the thermoplastic resin (A) forming the continuous phase (I) to the thermoplastic resin (B) forming the dispersed phase (II), which constitutes the regular reflection film (X), is (A) / (B) = 90% by mass / 10% by mass to 50% by mass / 50% by mass, preferably 80% by mass / 20% by mass to 55% by mass / 45% by mass, among which 75% by mass / 25 It is particularly preferable that the content is 60% by mass to 40% by mass. By setting it as such mixed mass ratio, a dispersed phase does not decrease too much, and scattering in the interface of a continuous phase and a dispersed phase becomes small, and there is no fear that a reflective characteristic may fall etc. It is preferable.
In addition, as long as the present reflective film contains at least one kind of each of the thermoplastic resin (A) and the thermoplastic resin (B), it may further contain other thermoplastic resin, for example, the heat Two or more kinds of thermoplastic resins corresponding to the plastic resin (B) may be contained.

(Other ingredients)
In order to improve the dispersibility of the regular reflection film (X), an additive such as a compatibilizer (C) may be added to the present reflection film as required.

  The compatibilizer (C) can be selected from conventional compatibilizers according to the types of continuous phase and dispersed phase in the regular reflection film (X), and examples thereof include polycarbonate resin, ester resin, and epoxy group. Block copolymers or graft copolymers comprising at least one resin selected from resins having an oxazoline ring and resins having an azlactone group, and at least one resin selected from styrenic resins, polyphenylene oxides, and polyamides; It can be mentioned. Among them, resins having an epoxy group or an oxazoline group are particularly preferable, and epoxy-modified resins are particularly preferable, from the viewpoint of improving the dispersibility.

  The compounding ratio in the case of adding a compatibilizer (C) is 0.1 to 20 parts by mass, preferably 0 based on 100 parts by mass in total of the thermoplastic resin (A) and the thermoplastic resin (B). The amount is preferably 2 to 15 parts by mass, particularly 0.2 to 10 parts by mass, and more preferably 1 to 10 parts by mass.

  In addition, as an additive other than the above-mentioned compatibilizer (C), an additive which is generally blended in a resin composition can be appropriately added within a range not to significantly inhibit the effect of the present invention. As the additives, flame retardants, weather resistant stabilizers, heat resistant stabilizers, antistatic agents, melt viscosity improvers are added for the purpose of improving and adjusting the molding processability, productivity and various physical properties of the present reflective film. Additives such as crosslinking agents, crosslinking agents, lubricants, nucleating agents, plasticizers, anti-aging agents, antioxidants, light stabilizers, UV absorbers, neutralizing agents, anti-fog agents, anti-blocking agents, slip agents or colorants Can be mentioned. Specifically, the antioxidants described in P154 to P158 of “plastics compounding agent”, the ultraviolet absorbers described in P178 to P182, and the interface as an antistatic agent described in P271 to P275 Activators and lubricants described in P283 to P294 can be mentioned.

(Dispersed diameter of dispersed phase (II))
The reflective film has an average dimension (L1) in the flow direction of the dispersed phase (II) and an average dimension (L2) in the width direction of 0.45 μm or more and 100 μm or less, and the dispersed phase (II) It is important that the average dimension (L3) in the thickness direction is 0.01 μm or more and 0.45 μm or less. The dispersion diameter can be measured by the method described later.

In the present reflective film, the dispersed phase (II) is in the shape of a flattened oval or disc. If the average dimension (L1) in the flow direction of the dispersed phase (II) and the average dimension (L2) in the width direction are 0.45 μm or more, they are sufficiently larger than the wavelength order of light, so The incident light can be sufficiently reflected at the interface between the continuous phase (I) and the dispersed phase (II), and high reflection characteristics can be imparted. From such a viewpoint, the lower limit value of L1 and L2 is more preferably 0.80 μm or more, and still more preferably 1.20 μm or more.
On the other hand, the upper limit value of L1 and L2 is preferably 80 μm or less, more preferably 50 μm or less, and still more preferably 20 μm or less, in order to improve the dispersibility.

In addition, the average dimension (L3) in the thickness direction of the dispersed phase (II) is 0.01 μm or more, 0. 0, or less.
It is important that it is 45 micrometers or less. When (L3) is 0.01 μm or more, in the cross section in the thickness direction of the present reflective film, a very thin cross section formed of the dispersed phase (II) is in a state in which several layers overlap. That is, it becomes possible to form a pseudo-super-multilayer structure by the inclusion of at least two types of thermoplastic resins having a sea-island structure of the continuous phase (I) and the dispersed phase (II). From this viewpoint, the lower limit value of (L3) is more preferably 0.02 μm or more, and still more preferably 0.03 μm or more.
Further, if the above (L3) is 0.45 μm or less, the thickness of the dispersed phase is sufficiently thin, so the surface roughness of the film surface is suppressed and it has a metallic-like gloss, high reflectance and positive It becomes possible to provide reflection characteristics. From such a viewpoint, the upper limit value of (L3) is more preferably 0.35 μm or less, and still more preferably 0.25 μm or less.

Average dimension (L1) in the flow direction of the dispersed phase (II), and average dimension (L2) in the width direction
Is not less than 0.45 μm and not more than 100 μm, and as the method of setting the average dimension (L3) in the thickness direction of the dispersed phase (II) to be not less than 0.01 μm and not more than 0.45 μm, the continuous phase (I) The thermoplastic resin (A) to form the thermoplastic resin (A) and the thermoplastic resin (B) to form the dispersed phase (II) are sufficiently incompatible with each other using a single screw extruder, a twin screw extruder or the like , A method of sufficiently stretching the thermoplastic resin (B) forming the dispersed phase (II) by uniaxial stretching, a thermoplastic resin (B) forming the dispersed phase (II) by simultaneous biaxial stretching A method of sufficiently elongating), a method of sufficiently elongating the thermoplastic resin (B) forming the dispersed phase (II) by sequential biaxial stretching, and a take-up speed (casting when forming a film by T-die casting) Speed of the roll) Method of sufficiently stretching the thermoplastic resin (B) to form the dispersed phase (II), the take-up speed is increased by the casting method, and the thermoplastic resin (B) to form the dispersed phase (II) is elongated After that, a method of stretching the thermoplastic resin (B) which further uniaxially stretches in the width direction to form the dispersed phase (II), and forming the film by the inflation method, the dispersed phase (II) The method of fully extending the thermoplastic resin (B) which forms II), the method of fully extending the thermoplastic resin (B) which forms said dispersed phase (II) by rolling or a press, etc. are mentioned.

<Diffuse reflection film (Y)>
The diffuse reflection film (Y) containing the fine powder filler that constitutes the present reflective film contains the fine powder filler and, in addition to the refractive scattering due to the refractive index difference with the polyolefin resin, It is also possible to obtain light reflectivity from refractive scattering due to the difference in refractive index with the cavity formed in the surrounding, and also from the refractive index difference due to the refractive index difference between the cavity formed around the powdery filler and the powdery filler. it can. In addition to refractive scattering due to the difference in refractive index, refractive scattering due to the difference in refractive index with the cavity formed around the powdery filler, and further the difference in refractive index between the cavity formed around the powdery filler and the powdery filler The light reflectivity can also be obtained from refractive scattering and the like.

(Polyolefin resin)
Examples of the polyolefin resin layer include polypropylene resins such as polypropylene and propylene-ethylene copolymer, polyethylene resins such as polyethylene, high density polyethylene and low density polyethylene, and cycloolefin resins such as ethylene-cyclic olefin copolymer And at least one polyolefin resin selected from olefin elastomers such as ethylene-propylene rubber (EPR) and ethylene-propylene-diene terpolymer (EPDM). Among them, polypropylene resin (PP), polyethylene resin (PE), and cycloolefin resin are preferable in view of mechanical properties and flexibility, and among them, they are particularly excellent in heat resistance and mechanical properties such as elastic modulus From the viewpoint of being high, polypropylene resin (PP) and cycloolefin resin (COC, COP) are preferable.

(Fine powder filler)
As fine powder fillers used for the diffuse reflection film (Y), inorganic fine powder, organic fine powder and the like can be mentioned.
As fine inorganic powder, for example, calcium carbonate, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, zinc oxide, magnesium oxide, calcium oxide, calcium oxide, titanium oxide, zinc oxide, alumina, aluminum hydroxide, hydroxyapatite, silica And mica, talc, kaolin, clay, glass powder, asbestos powder, zeolite, siliceous silica and the like. These may be used alone or in combination of two or more.
Among them, calcium carbonate, barium sulfate, titanium oxide or zinc oxide having a refractive index of 1.6 or more is preferable in consideration of the difference in refractive index with the polyolefin resin constituting the sheet. It is particularly preferred to use.

Among them, titanium oxide has a significantly higher refractive index than other powdery fillers, and has a significantly larger difference in refractive index with polyolefin resins, so it is less blended than when other powdery fillers are used. Excellent reflectivity can be obtained in quantity. Furthermore, by using titanium oxide, high light reflectivity can be obtained even if the thickness of the reflective material is reduced.
Therefore, it is more preferable to use a filler containing at least titanium oxide, and in this case, the amount of titanium oxide is 30% by mass or more of the total mass of the inorganic filler, or a combination of an organic filler and an inorganic filler When using, it is preferable to set it as 30 mass% or more of the total mass.

  In addition, in order to improve the dispersibility of the inorganic fine powder in the resin, the surface of the fine powder filler was surface-treated with a silicon compound, a polyhydric alcohol compound, an amine compound, a fatty acid, a fatty acid ester, etc. You may use one.

  On the other hand, as the above-mentioned organic fine powder, polymer beads, polymer hollow particles and the like can be mentioned, and these can be used alone or in combination of two or more. In addition, inorganic fine powder and organic fine powder may be used in combination.

  The fine powder filler preferably has a particle size of 0.05 μm to 15 μm, and more preferably 0.1 μm or more or 10 μm or less. When the particle size of the filler is 0.05 μm or more, the dispersibility in the olefin resin does not decrease, and a homogeneous sheet can be obtained. When the particle size is 15 μm or less, the interface between the olefin resin and the fine powder filler is densely formed, and a highly reflective reflective sheet can be obtained.

  As the content ratio of the polyolefin resin and the fine powder filler in the diffuse reflection film (Y), from the viewpoints of light reflectivity, mechanical strength, productivity and the like, polyolefin resin: fine powder filler = 80: 20 to 20 It is preferable to set it as 30:70, especially 80:20 to 60:40. When the content of the fine powder filler is 20% by mass or more, the area of the interface between the base resin and the fine powder filler can be sufficiently secured, and high reflectivity can be imparted to the reflective material. If the content of the powdery filler is 80% by mass or less, the mechanical strength necessary for the reflective sheet can be secured.

  In addition, as a method of forming a void in the diffuse reflection film (Y), for example, a method by stretching in at least a uniaxial direction or a method of adding foamable particles and performing melt extrusion by foaming In addition, there is a method of dissolving an inert gas under high pressure and then releasing the pressure to form a porous layer. Note that any one of these methods may be employed, or a plurality of methods may be employed in combination.

(Porosity)
The diffusive reflection film (Y) preferably has fine voids in the range of 20% to 80% in the inside, from the viewpoint of securing the reflection performance. More preferably, it is 25% to 75% or less, still more preferably 30% to 70% or less.

<Adhesive layer (Z)>
Among the reflective films, the adhesive layer (Z) made of a thermoplastic resin is not particularly limited as long as it does not deviate from the range defined in the present invention. For example, a maleic anhydride-modified polyolefin resin, an acrylic pressure-sensitive adhesive resin, or a mixture of a thermoplastic resin constituting the regular reflection film (X) and a thermoplastic resin constituting the diffusion reflection film (Y), etc. may be mentioned. Be Among them, polyolefin resins modified with maleic anhydride are preferable in consideration of both adhesion and ease of availability.

  A commercial item can also be used as a polyolefin resin acid-modified by the said maleic anhydride. For example, Admar (made by Mitsui Chemicals, Inc.), lauren (made by Nippon Paper Industries), DPA (made by DuPont) etc. can be mentioned as a preferable example.

<Shape and physical properties of this reflective film>
(Layer structure)
The present reflective film contains at least two types of thermoplastic resins, and a regular reflection film (X) having a sea-island structure with a continuous phase (I) and a dispersed phase (II), a polyolefin resin and a fine powder filler The configuration is not particularly limited as long as the diffuse reflection film (Y) containing the mixture as a main component is integrally laminated by coextrusion through the adhesive layer (Z) made of a thermoplastic resin. In addition, other layers P may be appropriately introduced as needed, such as mechanical characteristics and other improvements, as long as the scope of the present invention is not exceeded. For example, it can be superimposed on a metal plate to improve mechanical properties.
For example, in addition to the three-layer configuration of X / Z / Y, a four-layer configuration such as X / Z / Y / P, X / Z / Y / Z / X, X / Z / Y / P / Y, X 5-layer structure such as / Z / Y / P / X and X / Z / Y / Z / P, 7-layer structure such as X / Z / Y / P / Y / Z / X, X / Z / Y / Z It is also possible to have a 9-layer configuration such as / P / Z / Y / Z / X. Further, in forming a laminated structure, the resin composition of each layer may be the same or different.

(Thickness)
The thickness of the present reflective film is preferably 40 to 1000 μm. When the thickness of the present reflective film is 40 μm or more, sufficient reflectance and regular reflection characteristics can be obtained, and when it is 1000 μm or less, sufficient practical handleability can be obtained. From such a viewpoint, more preferably, it is 50 to 800 μm, and more preferably 60 to 400 μm.

(Thickness ratio)
The thickness of the regular reflection film (X) is 8 to 23%, preferably 10 to 17%, and more preferably 12 to 14% of the thickness of the present reflection film. The thickness of the diffuse reflection film (Y) is 70 to 90%, preferably 77 to 87%, and more preferably 82 to 84%. The thickness of the adhesive layer (Z) is 2 to 7%, preferably 3 to 6%, and more preferably 4 to 5%.
If the thickness ratio of each layer is in the above range, it is possible to efficiently impart regular reflection characteristics and high reflectance to the present reflective film. Moreover, the adhesiveness of the said regular reflection film (X) and the said diffuse reflection film (Y) can fully be ensured.

(Average reflectance and average transmittance)
It is important that the present reflective film has an average reflectance of 90% or more at a measurement wavelength of 400 nm to 700 nm. When the average reflectance is 90% or more, the reflection characteristics of the film can be secured. From such reasons, 95% or more is more preferable, and 97% or more is particularly preferable. If it has such reflection performance, it exhibits good reflection characteristics as a reflection material, and a liquid crystal display or the like incorporating this reflection material can achieve sufficient brightness on its screen.
Further, in the present reflective film, the transmittance in the visible light range (380 to 780 nm) is preferably 5% or less over the entire wavelength range. Thereby, transmission of the light of the back side of a reflective surface can be suppressed, and the reflective film excellent in light concealability can be obtained.
In order to bring the average reflectance and the average transmittance into the desired range, the average refractive index of the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin forming the dispersed phase (II) ( This can be achieved by controlling the absolute value of the difference from the average refractive index of B) and the dispersion diameter of the dispersed phase (II).

(Film forming method)
It does not restrict | limit especially as a manufacturing method of this reflection film, A well-known method is employable. Below, although an example is given and demonstrated about the manufacturing method of this reflection film provided with lamination structure, it is not limited at all to the following manufacturing method.

  First, a finely powdered filler and, if necessary, other additives are blended in advance in the polyolefin resin. Specifically, a fine powder filler and other antioxidants and the like are added to the polyolefin-based resin as required, and mixed by a ribbon blender, tumbler, Henschel mixer, etc., followed by a Banbury mixer, a single screw or twin screw extruder, etc. The resin composition for the sheet (Y) can be obtained by kneading at a temperature above the flow start temperature of the resin. Alternatively, it can be obtained by adding and kneading a predetermined amount of a polyolefin resin, a fine powder filler and the like by separate feeders and the like. In addition, so-called masterbatches are prepared in which polyolefin resins and other antioxidants and the like are previously blended at a high concentration, and this masterbatch is mixed with polyolefin resins and powdery fillers to adjust to a desired concentration. You can also

  On the other hand, if necessary, a compatibilizer (C), an antioxidant and the like are added to the thermoplastic resin (A) and the thermoplastic resin (B) to obtain a resin composition for the sheet (X). Specifically, it can be obtained by mixing using a ribbon blender, tumbler, Henschel mixer, etc., and then kneading at a temperature above the flow start temperature of the resin using a Banbury mixer, single-screw or twin-screw extruder, etc. . Also, a so-called masterbatch is prepared in which the thermoplastic resin (A) and the thermoplastic resin (B) are mixed with other compatibilizers (C), antioxidants, etc. in high concentration beforehand, and this masterbatch and thermal The plastic resin (A) and the thermoplastic resin (B) can be mixed to adjust to a desired concentration.

Next, after drying the resin composition for sheet (X) thus obtained and the resin composition for sheet (Y), the resin composition for sheet (X) and the thermoplastic resin for adhesive layer (Z) are separately prepared. The mixture is fed to the extruders of (1) and (2) and heated to melt at a predetermined temperature or higher.
The conditions such as the extrusion temperature and the like differ depending on the thermoplastic resin used for each layer, but in the case of using any resin, it is necessary to be set in consideration of the decrease in molecular weight due to decomposition and the like. For example, when using the thermoplastic resin mentioned in the above-mentioned example in each layer, the extrusion temperature of the resin composition for the said sheet (Y) and the thermoplastic resin for the said contact bonding layer (Z) is 220 degreeC-290 The extrusion temperature of the resin composition for the sheet (X) is preferably 270 ° C to 290 ° C.
Thereafter, each melted resin composition is joined to a T-die for three types, five layers, or three types, three layers, extruded from the slit-like discharge port of the T die into a laminated form, and solidified closely on a cooling roll to obtain a cast sheet Form

The present reflective film is preferably stretched in at least one direction. The stretching direction may be either MD or TD or both axes. However, in order to more effectively express the characteristics of the present reflective film, it is preferable to stretch in both MD and TD directions to orient the film. By stretching, the interface between the polyolefin resin and the powdery filler in the resin composition A peels off to form a void, whitening of the sheet proceeds, and the light reflectivity of the film can be enhanced.
As a method of orienting the film in both MD and TD directions, in addition to the method by the above-mentioned stretching, for example, when forming a film by T-die casting, MD can be made MD by increasing the take-up speed (speed of cast roll). For example, a method of drawing in TD after drafting, and a method of drawing in TD after drafting in MD by increasing the take-up speed when forming a film by inflation method can be exemplified.
Among them, when film formation stability and production efficiency are considered, it is preferable to select a method of biaxially stretching a sheet formed by T-die casting as described above into MD and TD.

By biaxially stretching in this manner, the dispersed phase (II) can be arranged and fixed in a substantially constant direction in the continuous phase (I), so that the continuous phase (I) and the dispersed phase (II) While the refractive index difference increases in the stretching direction, the dispersed phase (II) is elongated in the stretching direction, and the dispersed diameter of the dispersed phase is included in the preferred range of the present invention. Therefore, the dispersed phase (II) comes to have a pseudo super multilayer structure, and a reflective film having a metallic-like gloss can be produced. Further, by biaxial stretching, the peeling area at the interface between the polyolefin resin and the fine powder filler in the resin composition A is increased, and the whitening of the sheet further progresses, as a result, the light reflectivity of the film is increased. It can be further enhanced.
In addition, since the anisotropy in the shrinkage direction of the film decreases when biaxial stretching is performed, the heat resistance of the film can be improved, and the mechanical strength of the film can also be increased.

As a stretching method, any of a stretching method, a stretching method between rolls, a rolling method and other methods may be adopted.
The stretching temperature is preferably a temperature within the range of about the glass transition temperature (Tg) of the resin to (Tg + 50 ° C.). When the stretching temperature is in this range, the stretching can be stably performed without breakage at the time of stretching.
The stretching ratio is not particularly limited. For example, it is preferable to use 2 to 9 times for MD and / or TD, preferably 3 to 9 times for MD and / or TD, and particularly 4 to 7 times for MD and / or TD. When the stretching ratio is 2 times or more in MD and / or TD, the dispersed phase (II) in the regular reflection sheet (X) is extended, it becomes easy to adjust to the range specified by the present invention, and the diffuse reflection sheet ( It is preferable because the peeling area at the interface between the polyolefin resin and the fine powder filler in Y) is increased. Further, the difference in refractive index between the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase is increased by the orientation, and the effect of improving the reflectance can be obtained. Because it is preferable. On the other hand, if it is 9 times or less, since breakage of a film can be controlled, it is preferred.

The stretched sheet is preferably heat-treated to impart heat resistance and dimensional stability.
The heat treatment temperature depends on the resin to be used, but in the case of using the resin composition described in the above example, it is preferably 140 to 170 ° C., and more preferably 150 to 160 ° C. The treatment time required for the heat treatment is preferably 1 second to 5 minutes.

(Peeling strength)
The peel strength between the regular reflection film (X) and the diffuse reflection film (Y) in the present reflection film is preferably 0.7 N / cm or more, more preferably 0.8 N / cm or more, 1.0 N It is more preferable that it is / cm or more. If the peel strength is 0.7 or more, sufficient adhesion that the regular reflection film (X) and the diffuse reflection film (Y) do not peel can be obtained in practical handling.

(Regular reflection characteristics)
It is preferable to show regular reflectivity as the reflection characteristic of the present reflection film. As a method of evaluating the reflection characteristics, there is a variable angle photometry, for example, when light is incident on the sample with the normal direction to the surface of the film as 0 ° and the incident angle as −X °, the sample In the case of diffuse reflection, the reflected light is reflected with spread at various angles. On the other hand, when the sample exhibits regular reflectivity, the distribution of the reflected light shows a reflected light distribution with the reflection angle X ° as a peak. At this time, the peak appears sharper as the specular reflection is higher. At this time, the maximum intensity of the peak of the reflected light is normalized to 100%, and when the horizontal bearing light angle and the vertical axis light reception relative peak intensity are taken, the light reception angle width at which the light reception relative peak intensity becomes 1% and 10% is It becomes an index of regular reflection characteristics.
The light receiving angular width of this light receiving relative peak intensity 10% is preferably 10 ° or less. If it is 10 degrees or less, reflected light with strong directivity can be obtained with respect to the incident angle, and excellent specular reflection characteristics are exhibited. Moreover, it is preferable that the light reception angle width | variety of light reception relative peak intensity 1% is 50 degrees or less. If the angle is 50 ° or less, loss of incident light can be prevented with respect to the incident angle, reflected light with high directivity can be obtained, and excellent specular reflection characteristics are exhibited.

(Surface roughness)
The surface roughness of the present reflective film is 0. 0 as the arithmetic mean roughness Ra of at least one surface.
It is preferable that it is 2 micrometers or less, and it is more preferable that it is 0.15 micrometers or less. As a means for making arithmetic mean roughness Ra into the above-mentioned range, for example, when ethylene-tetrafluoroethylene-based resin which is a fluorine-based resin is used for dispersed phase (II), one having a melting point in a predetermined range It can be adjusted by selecting it. When the melting point of the resin is 130 ° C. or more and 250 ° C. or less, elongation deformation is facilitated, so surface roughness can be prevented.
At the time of film formation, the melted composition is extruded from the slit-like discharge port of the T die,
When solidifying in close contact with a cooling roll, sandwiching both sides of a molten resin composition with a film excellent in smoothness, or bonding one surface of a molten resin composition with a film excellent in smoothness, smoothness Surface roughness can also be prevented by pressing an excellent metal film or metal belt.

<Explanation of terms>
The form of the present reflective film is not particularly limited, and includes plate-like, sheet-like, film-like and other forms.

  In general, “film” is a thin flat product whose thickness is extremely small compared to the length and width, and the maximum thickness is arbitrarily limited, and is usually supplied in the form of a roll (Japanese Industrial Standard JIS K 6900), generally "sheet", is thin according to the definition in JIS, and generally refers to a small flat product having a small thickness depending on length and width. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish between the two in the present invention, in the present invention, even when it is referred to as "film", "sheet" is included and referred to as "sheet". Even in the case of "film" shall be included.

  The reflective film proposed by the present invention has high reflective properties and regular reflective properties, and has a metallic-like luster, and thus can be widely used in applications such as liquid crystal display devices, lighting devices, decorative articles, etc. .

  Hereinafter, the present invention will be more specifically described by way of examples. However, the present invention is not limited to these, and various applications are possible without departing from the technical concept of the present invention.

<Measurement and evaluation method>
First, measurement methods and evaluation methods of various physical property values of samples obtained in Examples and Comparative Examples will be described.

(1) Difference in average refractive index between thermoplastic resin (A) and thermoplastic resin (B) Using an Atago Abbe refractometer, using sodium D line (589 nm) as a light source, JIS
After measuring the average refractive index of each raw material used for the Example and the comparative example by K7124, the average refractive index difference was computed.

(2) Thickness The total thickness of the obtained reflective film was measured at five places in the plane unspecified with a dial gauge of 1/1000 mm, and the average was taken as the thickness.
Regarding the thickness of each layer of the regular reflection film (X), the diffuse reflection film (Y), and the adhesive layer (Z), the cross section of the film obtained by a scanning electron microscope (SEM) is observed, and the obtained photograph is used It was measured.

(3) Evaluation method of reflectance An integrating sphere is attached to a spectrophotometer (“U-3900H” manufactured by Hitachi, Ltd.), and the reflectance when an alumina white plate is 100% is 0 over a wavelength of 300 nm to 800 nm. The reflectance was obtained at intervals of 5 nm. The average value in each wavelength range was calculated based on the obtained measured value, and this value was defined as the average reflectance (%).

(4) Method of evaluating the transmittance Attach an integrating sphere to a spectrophotometer (“U-3900H”, manufactured by Hitachi, Ltd.), measure at a wavelength of 300 nm to 800 nm at intervals of 0.5 nm, and measure the transmittance (%) Obtained. Before the measurement, calibration was performed using an alumina white plate as a standard plate.

(5) Average dimension in the flow direction of the dispersed phase (II) (L1)
The MD cross section of the obtained film was observed with a scanning electron microscope (SEM), and the average value of the dispersion diameter of the dispersed phase (II) was calculated from the obtained photograph, and judged based on the following criteria.
○: The average dimension (L1) is at least 0.45 μm and at most 100 μm.
X: The average dimension (L1) is less than 0.45 μm or greater than 100 μm.

(6) Average dimension in the width direction of the dispersed phase (II) (L2)
The TD cross section of the obtained film was observed with a scanning electron microscope (SEM), and the average value of the dispersion diameter of the dispersed phase (II) was calculated from the obtained photograph, and judged based on the following criteria.
○: The average dimension (L2) is not less than 0.45 μm and not more than 100 μm.
X: The average dimension (L2) is less than 0.45 μm or greater than 100 μm.

(7) Average dimension in the thickness direction of the dispersed phase (II) (L3)
The MD cross section and the TD cross section of the obtained film were observed with a scanning electron microscope (SEM), and the average value of the dispersion diameter of the dispersed phase (II) was calculated from the obtained photograph, and judged based on the following criteria.
○: The average dimension (L3) is 0.01 μm or more and 0.45 μm or less.
X: The average dimension (L3) is less than 0.01 μm or greater than 0.45 μm.

(8) Variable angle photometric measurement: A gonio photometer GR200 (made by Murakami Color Research Laboratory, using an automatic variable angle photometer),
Light was incident on the sample at a normal direction of 0 ° with respect to the surface of the film and an incident angle of −45 °, and the light reflected on the film in the range of −60 ° to 90 ° was received. At this time, the maximum intensity of the obtained peak was normalized to 100%, and a graph of the lateral bearing light angle and the vertical axis received relative peak intensity was created. From the obtained graph, the light receiving angular width at which the light receiving relative peak intensity is 1% and 10% was calculated. The smaller the light receiving angular width, the stronger the regular reflection. From the obtained result, it judged on the following reference | standard.
Good: The light receiving angular width of 10% of the light receiving relative peak intensity is 10 ° or less.
×: A light receiving angular width of 10% of light receiving relative peak intensity is larger than 10 °.
Good: The light receiving angle width of the light receiving relative peak intensity 1% is 50 ° or less.
×: A light receiving angular width of 1% of light receiving relative peak intensity is larger than 50 °.

(9) Arithmetic mean roughness Ra
It conforms to JIS B0601-2001.
First, a reflective film is cut out to have a width of 9 mm and a length of 6 mm. Cut out the reflective film,
Stick on carbon double-sided tape (manufactured by Nisshin EM Co., Ltd.) on a holder for observation. Then, in order to prevent charge (charge up) on the sample surface at the time of observation, a conductive paste is placed on six places around the sample, and Pt—Pd is deposited on the surface for 10 seconds at 10 mA. The sample was observed with an ESA-2000 (manufactured by Elionix Co., non-contact three-dimensional roughness meter) at a measurement magnification of 250 times (measurement range: 480 μm × 360 μm) to calculate the arithmetic average roughness Ra.
;: Arithmetic mean roughness Ra is 0.15 μm or less ×; Arithmetic mean roughness Ra exceeds 0.15 μm.

(10) Thermal contraction rate About the obtained reflective film, the marking line of a 100-mm space | interval was drawn along the measurement direction, and it hung in the oven preheated to 90 degreeC beforehand. After 30 minutes, the sample was taken out and allowed to cool to room temperature, and then the length between the marked lines of the sample was measured with a metal scale, and the change before and after heating was taken as the shrinkage rate. The measurement direction was measured in both MD and TD.
;; heat shrinkage of not more than 0.5% x; heat shrinkage of more than 0.5%.

(11) Porosity Measure the density of the film before drawing (denoted as _{B B} ) and the density of the film after drawing (denoted as ρ _A ), and substitute the following equation to the porosity of the film (%) I asked for.
Porosity (%) = {(ρ _B −− _A ) / ρ _B } × 100

(12) Peeling Strength The peeling strength of the regular reflection film (X) and the diffuse reflection film (Y) was measured in accordance with JIS Z0237. First, a sample is cut out 50 mm wide × 150 mm long, and a cellophane tape (manufactured by Nichiban, JIS Z1522) is attached as a tape 43 in the longitudinal direction of the sample, folded back at 180 ° so that the back of the tape overlaps, I peeled off 25 mm. Next, fix one end of the peeled sample to the lower chuck of a tensile tester (Intesco, Intesco IM-20ST), fix the tape to the upper chuck, and measure the adhesive strength at a test speed of 300 mm / min. did. After measurement, ignore the first measurement of 25 mm in length, average the peel strength measurement of 50 mm in length peeled off from the test piece, and divide the strength value by the tape width to obtain the peel strength. . The measurement direction was measured in both MD and TD.
;; Peeling strength is 1.0 N / cm or more ×; Peeling strength is less than 1.0 N / cm

<Resin composition for regular reflection film (X)>
Polyethylene naphthalate resin as thermoplastic resin (A) (average refractive index: 1.646, Tg: 118 ° C, Tm: 261 ° C, intrinsic viscosity 0.71 dl / g, weight average molecular weight 50,000, intrinsic birefringence: Positive, hereinafter referred to as A-1), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride system (3M company, Dyneon THV 815 GZ; average refractive index: 1.3547, Tm: as thermoplastic resin (B) The mixture was mixed at a mass mixing ratio of 70 ° C. with 223 ° C. (hereinafter referred to as B-1) and sufficiently mixed, and then pelletized using a twin-screw extruder heated at 290 ° C. to form a specular reflection film (X Resin composition was prepared.

<Resin composition for diffuse reflection film (Y)>
Metal soap (Nippon Kasei Kogyo Co., Ltd.) after mixing with a pellet of polypropylene resin (Nippon Polypro Co., Ltd., trade name "Novatec PP FY6 HA) and titanium oxide (KRONOS, trade name" KRONOS 2450) at a mass ratio of 55: 45 Industrial ZS-6), antioxidants (ADEKA PEP 36 and AO-80), beta crystal nucleating agents (3,9-bis [4- (N-cyclohexylcarbamoyl) phenyl] -2,4,8,10-tetraoxax 0.2, 0.1, 0.1, 0.08 parts of spiro [5.5] undecane) is added to each mixed mass 100, and pelletized using a twin-screw extruder heated at 250 ° C. The resin composition for diffuse reflection film (Y) was produced.

Example 1
The resin composition for the regular reflection film (X), the resin composition for the diffusion reflection film (Y), and the thermoplastic resin for the adhesive layer (Z), maleic anhydride modified PO (Mitsui Chemical Co. Admer SF7311 ) Are fed to extruders A, B and C heated to 290 ° C., 230 ° C. and 230 ° C., respectively, and after melt-kneading at 290 ° C. and 230 ° C. in each extruder, Merge into a T-die, and extrude it into a sheet shape so that it has a five-layer configuration of regular reflection film (X) / adhesion layer (Z) / diffuse reflection film (Y) / adhesion layer (Z) / regular reflection film (X) The film was cooled and solidified by a cast roll having a roll temperature of 127 ° C. to obtain a laminated sheet.
The cast sheet thus obtained was subjected to MD by the roll speed difference between the stretching rolls at a preheating temperature of 120 ° C., a stretching temperature of 130 ° C., and a cooling temperature of 60 ° C. in a longitudinal stretching machine consisting of a preheating roll, a drawing roll and a cooling roll. Stretched 2.7 times.
Then, the obtained longitudinally stretched film was stretched 4.2 times to TD at a preheating temperature of 140 ° C., stretching of 136 ° C., and heat treatment of 155 ° C. in a tenter consisting of a preheating zone, a stretching zone and a heat treatment zone. The transit time of the preheating zone, the drawing zone and the heat treatment zone was 32 seconds respectively. The evaluation results of the obtained reflective film are shown in Table 1.

Example 2
In Example 1, ethylene-tetrafluoroethylene-based resin (Fluon LM-720AP, manufactured by Asahi Glass Co., Ltd .; average refractive index: 1.3795, Tm: 227 ° C., B-2) instead of the thermoplastic resin B-1 A reflective film was obtained in the same manner as in Example 1 except that the symbol (1) was used. The evaluation results of the obtained reflective film are shown in Table 1.

Comparative Example 1
Example 2 was the same as Example 2 except that the sheet was extruded so as to have a three-layer configuration of regular reflection film (X) / diffuse reflection film (Y) / regular reflection film (X). However, since the adhesive layer (Z) was not provided, the regular reflection film (X) and the diffuse reflection film (Y) did not adhere to each other in the obtained cast sheet, and it was not possible to stretch.

Comparative Example 2
In Example 2, after melt-kneading the resin composition for regular reflection film (X), it is cooled and solidified by a cast roll having a roll temperature of 110 ° C. to form a regular reflection film (X) single-layer sheet having a thickness of 950 μm. It produced similarly to Example 2 except having extruded as mentioned above.
The obtained sheet is subjected to MD by a roll speed difference between the stretching rolls at a preheating temperature of 120 ° C., a stretching temperature of 130 ° C., and a cooling temperature of 70 ° C. in a longitudinal stretching machine comprising a preheating roll, a stretching roll and a cooling roll. It was stretched 3 times.
Thereafter, the obtained longitudinally stretched film was stretched by a factor of 4 in a TD at 130 ° C. preheating, 130 ° C. stretching and 180 ° C. heat treatment in a tenter consisting of a preheating zone, a stretching zone and a heat treatment zone. The transit time of the preheating zone, the drawing zone and the heat treatment zone was 32 seconds respectively. The evaluation results of the obtained film are shown in Table 1.

Comparative Example 3
In Comparative Example 2, in place of the thermoplastic resin B-2, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride resin (manufactured by 3M, THV221GZ; average refractive index: 1.363, Tm: 113 ° C., intrinsic compound A film was obtained in the same manner as in Comparative Example 2 except that the refractive index: positive, hereinafter referred to as B-3) was used. The evaluation results of the obtained film are shown in Table 1.

As is clear from the above results, in the reflective films of Examples 1 to 2, the regular reflection film (X) having a sea-island structure with the continuous phase (I) and the dispersed phase (II), the polyolefin resin, and the fine powder filling And the diffuse reflection film (Y) containing as a main component a mixture with an agent are laminated and integrated by coextrusion through the adhesive layer (Z) made of a thermoplastic resin, so that high reflection derived from the laminated structure It can be seen that it is a suitable reflective film with a metal-like luster, which has a high modulus, high specular reflection properties, and excellent surface smoothness.
On the other hand, when it did not have an adhesive layer (Z) (comparative example 1), the sheet worthy of evaluation was not obtained. Moreover, when it did not have diffuse reflection film (Y) (comparative example 2), the reflective characteristic was inadequate. Furthermore, as compared with Comparative Example 2, the sheet (Comparative Example 3) in which the average dimension (L3) in the thickness direction is equal to or larger than the specified value was further inferior in regular reflection characteristics and reflectance.

Claims (11)

A specular reflection film (X) containing at least two thermoplastic resins and having a sea-island structure by a continuous phase (I) and a dispersed phase (II), and a mixture of a polyolefin resin and a fine powder filler as the main components A diffuse film (Y) to be integrated by coextrusion through a bonding layer (Z) made of a thermoplastic resin.
The average dimension (L1) in the flow direction of the dispersed phase (II) and the average dimension (L2) in the width direction are 0.45 μm or more and 100 μm or less, and the average dimension in the thickness direction of the dispersed phase (II) (L3) is 0.01 μm or more and 0.45 μm or less, and the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) The average refractive index difference is 0.05 or more,
And the reflective film characterized by an average reflectance of 90% or more at a measurement wavelength of 400 nm to 700 nm.   Either the thermoplastic resin (A) forming the continuous phase (I) or the thermoplastic resin (B) forming the dispersed phase (II) is mainly composed of a polyester resin, and the other is 2. A reflective film according to claim 1, which is mainly composed of a fluorine-based resin.   The reflective film according to claim 2, wherein the polyester thermoplastic resin is a polyethylene naphthalate resin. The reflective film according to claim 2 or 3, wherein the fluorine-based thermoplastic resin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride resin or an ethylene-tetrafluoroethylene resin.   It is extended | stretched at least uniaxial direction, The reflective film of any one of the Claims 1-4 characterized by the above-mentioned.   The reflective film according to any one of claims 1 to 5, wherein the film is stretched by 2 to 9 times in the flow direction of the film and / or the width direction of the film.   The reflective film according to any one of claims 1 to 6, wherein arithmetic mean roughness Ra of at least one surface is 0.2 μm or less. The light receiving angular width of at least light receiving relative peak intensity 10% is 10 ° or less, or the light receiving angular width of 1% of light receiving relative peak intensity is 50 ° or less. Reflective film described in. A liquid crystal display comprising the reflective film according to any one of claims 1 to 8 . A lighting device comprising the reflective film according to any one of claims 1 to 8 . A decorative article comprising the reflective film according to any one of claims 1 to 8 .