JP4742566B2 - Biaxially stretched laminated film, laminated glass film and laminated glass - Google Patents

Description

  The present invention relates to a biaxially stretched laminated film, a laminated glass film, and a laminated glass.

  More specifically, the present invention relates to a biaxially stretched laminated film and a laminated glass suitable as an interlayer film for laminated glass having a good appearance and excellent scattering prevention and crime prevention performance.

  Various films in which polyester is laminated in multiple layers have been proposed. For example, by attaching a film laminated in a multilayer having excellent tear resistance to the glass surface, glass damage and scattering can be significantly prevented (for example, Patent Documents 1 to 3) exist. However, these anti-scattering films for pasting windows are not satisfactory for the recent demands for high crime prevention performance. In addition, there is a problem that workability is inferior due to poor appearance due to interference fringes and interference colors due to the multilayer structure and poor flatness due to large thickness unevenness.

On the other hand, it is difficult to break and pry, so that it is difficult to break and punch holes, that is, crime prevention glass that emphasizes impact resistance and penetration resistance against physical impact, for example, polyvinyl butyral which is an interlayer film of laminated glass (PVB) thickened so that holes are not easily opened, and a thick polycarbonate plate with high impact resistance is inserted into the interlayer film of laminated glass, and is integrated with ethylene-vinyl acetate copolymer (EVA). Laminated glass and the like are commercially available. Further, there has been proposed a laminated glass in which two or more kinds of resin intermediate films having different Young's moduli are stacked and inserted between glass plates and bonded and integrated (for example, see Patent Document 4). Regarding these, although high crime prevention performance can be obtained, there is a problem that since the thickness of the interlayer film is large, the entire laminated glass is too thick and it is difficult to construct for general household use.
Japanese Patent Laid-Open No. 6-190995 (page 2) Japanese Patent Laid-Open No. 6-190997 (page 2) JP 10-76620 A (2nd page) JP2003-192402 (2nd page)

  An object of the present invention is to solve such problems, and to provide a film and laminated glass suitable as an interlayer film for laminated glass having a thin laminated glass, excellent crime prevention performance and good appearance.

In order to solve the above problems, the present invention has the following configuration. That is, it is a film having at least a layer made of polyester A and a layer made of polyester B, and each layer is laminated in two or more layers, and has an internal haze of 1.5% or less, and light rays in the visible light region. difference between the maximum value and the minimum value of the transmittance is 12% or less, and the film a biaxially oriented laminated film, wherein the longitudinal and thickness unevenness in the width direction is less than 6%, 110 ° C. After heat treatment at 200 ° C. or lower and relaxation treatment at 3% to 15% at the same temperature, polyester (A) and polyester B (glass transition temperature +10) ° C. Glass transition temperature +30) A biaxially stretched laminated film obtained by slow cooling at 5 ° C. or lower for 5 seconds or more .

  A film having at least a layer made of polyester A and a layer made of polyester B, each layer being laminated two or more layers, the internal haze is 1.5% or less, and the light transmittance in the visible light region Since the biaxially stretched laminated film is characterized in that the difference between the maximum value and the minimum value is 12% or less and the thickness unevenness in the longitudinal direction and the width direction of the film is 6% or less. When formed into a film, the laminated glass is thin, has a good appearance, and is excellent in crime prevention performance.

  In order to achieve the above object, the biaxially stretched laminated film of the present invention is a biaxially stretched laminated film having at least a layer made of polyester A and a layer made of polyester B, and each layer is laminated in two or more layers. There must be. By adopting such a configuration, it has a high elastic modulus and a high strength, yet has a high tear resistance, and when it is used as an interlayer film for laminated glass, it is difficult to shake and torn.

  Moreover, the internal haze of the biaxially stretched laminated film of the present invention must be 1.5% or less. More preferably, it is 1.0% or less, More preferably, it is 0.5% or less. This is because when the internal haze is 1.5% or more, the visual field becomes cloudy when the laminated glass is used.

In the biaxially stretched laminated film of the present invention, the difference between the maximum value and the minimum value of the light transmittance in the visible light region must be 12% or less. More preferably, it is 9% or less, More preferably, it is 8% or less. Here, the visible light region means a range from 400 nm to 800 nm. Usually, when a biaxially stretched laminated film made of two or more layers is used as an interlayer film of laminated glass, rainbow-like interference occurs due to interference, especially under a dark background, due to the difference in refractive index between the layers. This is because stripes may be seen, which makes it unsuitable as a laminated glass. Further, in the biaxially stretched laminated film of the present invention, the thickness unevenness in the longitudinal direction and the width direction of the film must be 6% or less. More preferably, it is 3% or less. When the thickness unevenness in the longitudinal direction and the width direction of the film is larger than 6%, it becomes easy to wrinkle in the thermocompression bonding process when making a laminated glass. Since the stripes are particularly easy to see, it is not preferable.

  In the biaxially stretched laminated film of the present invention, the number of layers is more preferably 4 or more, and more preferably 8 or more of each layer is laminated. When the number of layers is less than 2, it is not preferable because sufficient tear resistance and impact resistance cannot be obtained. Further, the upper limit of the number of layers is not particularly limited, and may be, for example, about several hundred layers, but is preferably about 600 layers or 1000 layers from the viewpoint of production. Therefore, the preferable number of layers is 10 to 1000 layers, and more preferably 20 to 600 layers. Particularly preferred is 120 to 390 layers. When the number of laminated layers is 120 to 390 layers, it is possible to have high security performance even when the laminated glass has a very thin thickness of 4600 μm to 6700 μm.

  Moreover, as a structure of a layer, it is preferable that the part which has the structure which laminated | stacked the layer which has at least polyester A as a main component and the layer which has polyester B as a main component regularly in the thickness direction exists. That is, it is preferable that the order of arrangement in the thickness direction of the layer containing polyester A as a main component and the layer containing polyester B as a main component in the film of the present invention is not in a random state. The order of the arrangement of the third layer or more other than the layer and the layer mainly composed of polyester B is not particularly limited. Moreover, when it consists of three types of polyester A, polyester B, and thermoplastic resin C, it is more laminated in a regular permutation such as A (BCA) n, A (BCBA) n, A (BABCBA) n. preferable. Here, n is the number of repeating units. For example, in the case of A (BCA) n where n = 3, this indicates that the layers are stacked in a permutation of ABCABCABCA in the thickness direction.

  Further, the polyester A and the polyester B in the present invention are selected from homopolyesters and copolymer polyesters that are polycondensates of a dicarboxylic acid component skeleton and a diol component skeleton. Here, typical examples of the homopolyester include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and the like. In particular, since polyethylene terephthalate is inexpensive, it can be used for a wide variety of applications and is highly effective.

  The copolyester in the present invention is defined as a polycondensate comprising at least three or more components selected from the following dicarboxylic acid component skeleton and diol component skeleton. Dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene acid, 1,5-naphthalene acid, 2,6-naphthalene acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyl Examples thereof include sulfone dicarboxylic acid, adipic acid, sebacic acid, dimer acid, cyclohexane dicarboxylic acid and ester derivatives thereof. 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentadiol, diethylene glycol, polyalkylene glycol, 2,2-bis (4′-β-hydroxyethoxy) as the glycol component Phenyl) propane, isosorbate, 1,4-cyclohexanedimethanol and the like.

  These polyesters may be two or more kinds of blends other than homopolyester and copolymer polyester. In each layer, various additives such as an antioxidant, an antistatic agent, a crystal nucleating agent, inorganic particles, organic particles, a thinning agent, a heat stabilizer, a lubricant, an infrared absorber, and an ultraviolet absorber are included. It may be added.

  In the present invention, in particular, a layer mainly composed of polyethylene terephthalate or polyethylene naphthalate and a layer mainly composed of a copolymer polyester mainly composed of 1,4-cyclohexanedimethanol are laminated alternately in the thickness direction. It is preferable. More preferably, a layer mainly composed of polyethylene terephthalate and a layer mainly composed of a copolyester having 1,4-cyclohexanedimethanol as a constituent component are alternately laminated in the thickness direction. More preferably, layers mainly composed of polyethylene terephthalate and layers composed mainly of polyethylene terephthalate copolymerized with 15 to 45 mol% of 1,4-cyclohexanedimethanol are alternately laminated in the thickness direction. ing. In the case of such a configuration, the tear resistance, impact resistance, and high transparency as the object of the present invention can be achieved efficiently and simultaneously. Thus, in the case of a layer containing a polyester having 1,4-cyclohexanedimethanol as a constituent component, the polyester having 1,4-cyclohexanedimethanol as a constituent component is rigid and excellent in impact absorption. Therefore, the propagation of cracks transmitted by impact is suppressed by the layer containing polyester having 1,4-cyclohexanedimethanol as a constituent component, so that improvement in tear resistance and impact resistance can be achieved. In addition, a layer containing a polyester having 1,4-cyclohexanedimethanol as a constituent component is excellent in transparency, and is excellent in visibility because it hardly changes with time at room temperature and whitens.

  The polyester or copolymer polyester of the present invention preferably has a tensile modulus of 1.4 GPa or more. More preferably, it is 2.0 GPa or more. Such a laminated film made of polyester is excellent in transparency and has high penetration resistance and anti-scattering properties when laminated glass is used as in the present invention. This is because when the polyester layer or copolymer polyester layer constituting the laminated film has a tensile elastic modulus of less than 1.4 GPa, the laminated film is greatly deformed, so that the glass easily falls off.

  The biaxially stretched laminated film of the present invention preferably has a tear strength in the longitudinal direction and width direction of the film of 50 N / mm or more. More preferably, it is 60 N / mm or more, More preferably, it is 80 N / mm or more. Although an upper limit is not specifically limited, Preferably it is 1000 N / mm or less. By having such a high tear strength, it becomes very difficult to tear as an interlayer film for laminated glass.

  Moreover, it is preferable that the Young's modulus of the longitudinal direction and the width direction of a film is 3 GPa or more. More preferably, it is 3.5 GPa or more. Although an upper limit is not specifically limited, Preferably it is 8 GPa or less. Thus, when having a high elastic modulus, a high impact force can be absorbed.

  In the biaxially stretched laminated film of the present invention, the heat shrinkage rate at 100 ° C. in the longitudinal direction and the width direction of the film is preferably 1.5% or less. More preferably, it is 1.0% or less. Such a film is preferable because it is difficult to cause wrinkles when thermocompression bonding with an ethylene vinyl-acetate film.

  In the biaxially stretched laminated film of the present invention, the thickness is preferably 50 μm or more and 1100 μm or less. More preferably, they are 200 micrometers or more and 900 micrometers or less. Furthermore, it is preferably 75 μm or more and 450 μm or less. When the film thickness is less than 50 μm, sufficient penetration resistance performance is not exhibited, and thermocompression processing when making a laminated glass becomes difficult. On the other hand, when the film thickness is 1100 μm or more, the film surface is likely to be damaged in the film-forming process, resulting in increased defects, which is not preferable. Moreover, since the thickness becomes too thick, handling becomes worse and it is difficult to construct a sash for general households. The thickness of the biaxially stretched laminated film referred to here may be a biaxially stretched laminated film alone or a film in which the biaxially stretched laminated film is bonded with an adhesive layer or an adhesive layer of 0 to 50 μm or less.

The laminated glass of the present invention comprises the above biaxially stretched laminated film and glass.
More preferably, the biaxially stretched laminated film of the present invention, a film made of polyvinyl butyral (PVB film) and / or a film made of an ethylene-vinyl acetate copolymer (EVA film), and glass. preferable. More preferably, a biaxially stretched laminated film of the present invention having an ethylene-vinyl acetate copolymer film (EVA film) disposed as an intermediate film between two glass plates is inserted. Is.

  The film made of ethylene-vinyl acetate (EVA film) preferably has an ultraviolet transmittance of 5% or less. More preferably, it is 1% or less. Thus, when the film (EVA film) made of ethylene-vinyl acetate cuts ultraviolet rays, the biaxially stretched laminated film of the present invention inserted as an intermediate film is less likely to deteriorate, and the elastic modulus and strength over time, Decrease in tear strength is unlikely to occur, and high crime prevention performance can be maintained over a long period of time.

  The laminated glass of the present invention preferably has a thickness of 4600 μm or more and 6700 μm or less. When the thickness of the laminated glass is thinner than 4600 μm, the crime prevention performance is insufficient. Moreover, when thicker than 6700 micrometers, it becomes difficult to pass P5A of a crime prevention standard. In general, when the thickness is larger, the penetration resistance is improved, but in the case of the laminated glass using the laminated film of the present invention, if the thickness becomes too thick, the rigidity of the laminated glass itself becomes too high. , Shock is not absorbed and it is difficult to pass high security standards.

  On the other hand, even if the thickness of the laminated glass is thicker than 6700 μm, if the total thickness of each of the film made of glass or polyvinyl butyral (PVB film) or the film made of ethylene vinyl acetate copolymer (EVA film) is increased, Although it is possible to pass P5A, in this case, interference fringes are easily generated and the appearance is slightly inferior. Even if the PVB film and EVA film are made thicker and pass high security performance, they are too heavy and difficult to handle, and cannot be attached to sashes of normal standards (6800 μm or less). There is also a problem.

  In order to set the preferred thickness of the laminated glass of the present invention to 4600 μm or more and 6700 μm or less, the thickness of the biaxially stretched laminated film is preferably 500 μm or more and 1100 μm or less. Moreover, it is also preferable that the lamination | stacking number of a biaxially stretched laminated film is 120-390 layers. Moreover, it is preferable that the thickness of glass is 1500 micrometers or more and 3000 micrometers or less.

Next, the preferable manufacturing method of the biaxially stretched laminated film of this invention is demonstrated below.
Two kinds of polyesters A and B are prepared in the form of pellets. If necessary, various additives such as antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, organic particles, thickeners, thermal stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, etc. Although it may be added in the form of a master chip or direct addition, in order to make the internal haze 1.5% or less, it is preferable that particles having an average particle diameter of 30 nm or more are not contained other than the film surface. Moreover, in order to set the internal haze to 1.0% or less, the particles having an average particle diameter of 30 nm or more are not included other than the film surface, and the glass transition temperatures of the polyester A and the polyester B are 50 ° C. or more. preferable. Furthermore, in order to set the internal haze to 0.5% or less, it is preferable to arrange particles having an average particle size of 1000 nm or less only on the film surface so that the film surface roughness Ra is 50 nm or less. If necessary, the pellets are pre-dried in hot air or under vacuum and supplied to an extruder. In the extruder, the resin melted by heating to the melting point or higher is made uniform in the amount of resin extruded by a gear pump or the like, and foreign matter or modified resin is filtered through a filter or the like. Further, the resin is formed into a desired shape with a die and then discharged.

  As a method for obtaining the biaxially stretched laminated film of the present invention, the thickness accuracy of each layer constituting the laminated film is very important in order to reduce interference fringes. When the thickness of each layer constituting the laminated film has a large distribution in the film longitudinal direction and width direction, interference fringes and glare are particularly undesirable when laminated glass is used. Moreover, since the thickness nonuniformity of a laminated film will also become large when the thickness precision of each layer is bad, it is unpreferable. As a method for obtaining a laminated film that requires such high accuracy, a polyester resin fed from different flow paths using two or more extruders is used by using a multi-manifold die, a field block, a static mixer, or the like. A method of laminating in multiple layers can be used. Moreover, you may combine these arbitrarily. Here, in order to efficiently obtain the effects of the present invention, a multi-manifold die or a feed block capable of individually controlling the layer thickness for each layer is preferable. Furthermore, in order to control the thickness of each layer with high accuracy, a feed block in which fine holes for adjusting the flow rate of each layer are processed by electric discharge machining with a machining accuracy of 0.1 mm or less is preferable. At this time, in order to reduce nonuniformity of the resin temperature, heating by a heat medium circulation method is preferable. Moreover, in order to suppress the wall resistance in the feed block, the roughness of the wall surface is preferably 0.4 S or less, or the contact angle with water at room temperature is 30 ° or more. Furthermore, in order to make the color development due to interference inconspicuous when viewed from a direction almost horizontal to the glass surface, the thickness of each layer and each layer so that the high-order reflection wavelength does not exist in the region of 500 nm to 900 nm. It is preferable to adjust the refractive index. Moreover, as a die | dye shape | molded here in a sheet form, it is preferable that the widening rate of the laminated body in die | dye is 1 time or more and 100 times or less. More preferably, it is 1 to 50 times. When the width-expansion ratio of the laminated body in the die is larger than 100 times, the disturbance of the laminated thickness of the surface layer of the laminated body increases, which is not preferable.

Also, the combination of the polyesters to be laminated is important in reducing interference fringes. In the present invention, in order to reduce the interference fringes, the difference between the maximum value and the minimum value of the light transmittance in the visible light region must be 12% or less. In order to achieve this, the following equation (Equation 1, It is preferable to design the layer structure so as to satisfy equation (2). By doing in this way, it becomes easy to suppress interference by interference reflection of a layer. Further, by combining any of the above-described methods, the difference between the maximum value and the minimum value of the light transmittance in the visible light region can easily be achieved at 9% or less, and by combining these all, % Or less can be achieved more easily.
200 ≧ n1 · d1 + n2 · d2 (Formula 1)
1600 ≦ n1 · d1 + n2 · d2 (Formula 2)
n1: Refractive index of polyester A d1: Average thickness of polyester A layer (nm)
n2: Refractive index of polyester B d2: Average thickness of polyester B layer (nm)
The multi-layered sheets discharged from the die are extruded onto a cooling body such as a casting drum, and cooled and solidified to obtain a casting film. At this time, using a wire-like, tape-like, needle-like or knife-like electrode, it is brought into close contact with a cooling body such as a casting drum by electrostatic force and rapidly cooled and solidified, or from a slit-like, spot-like, or planar device. A method in which air is blown out and brought into close contact with a cooling body such as a casting drum and rapidly cooled and solidified, and a method in which the nip roll is brought into close contact with the cooling body and rapidly solidified is preferable.

  The casting film thus obtained is preferably biaxially stretched as necessary. Biaxial stretching refers to stretching in the longitudinal direction and the transverse direction. Stretching may be performed sequentially biaxially or simultaneously in two directions. Further, re-stretching may be performed in the longitudinal and / or transverse direction.

  Here, the stretching in the longitudinal direction refers to stretching for imparting molecular orientation in the longitudinal direction to the film, and is usually performed by a difference in peripheral speed between rolls. This stretching may be performed in one stage, or may be performed in multiple stages using a plurality of roll pairs. Although it changes with kinds of resin as a magnification of extending | stretching, 2 to 15 times is preferable normally, and when the majority of resin which comprises a laminated | multilayer film uses a polyethylene terephthalate, 2 to 7 times is used especially preferable. Moreover, as extending | stretching temperature, the glass transition temperature-(glass transition temperature +100) degreeC of resin which comprises a laminated | multilayer film are preferable.

  The uniaxially stretched film thus obtained is subjected to surface treatment such as corona treatment, flame treatment, and plasma treatment as necessary, and then functions such as slipperiness, easy adhesion, and antistatic properties are provided. It may be applied by in-line coating. In particular, in order to make it easy to achieve an internal haze of 1.5% or less of the present invention, there are almost no particles inside the film, and particles that become a lubricant intensively in a layer provided by coating the film surface. Preferably it is present. More preferably, it is a coating layer comprising a polyester resin having a glass transition temperature of 30 ° C. or lower. Further, it is more preferable that the refractive index of the coating layer is intermediate between the refractive index of the member to be joined when the laminated glass is formed and the surface refractive index of the laminated film. More preferably, the refractive index of the coating layer varies between the surface and the laminated film adhesion surface.

  The stretching in the transverse direction refers to stretching for imparting the orientation in the width direction to the film. Usually, the film is stretched in the width direction by using a tenter while conveying both ends of the film with clips. Although it changes with kinds of resin as a magnification of extending | stretching, 2 to 15 times is preferable normally, and when the majority of resin which comprises a laminated | multilayer film uses a polyethylene terephthalate, 2 to 7 times is used especially preferable. The stretching temperature is preferably from the glass transition temperature of the resin constituting the laminated film to (glass transition temperature + 120) ° C.

  The biaxially stretched film is preferably subjected to a heat treatment at a temperature not lower than the stretching temperature and not higher than the melting point in the tenter in order to impart flatness and dimensional stability. After being heat-treated in this way, it is gradually cooled down uniformly, then cooled to room temperature and wound up. Moreover, you may use a relaxation process etc. together in the case of annealing from heat processing as needed.

In the present invention, the thickness unevenness in the longitudinal direction and the width direction of the film must be 6% or less, but in order to achieve this, it is necessary to remove the cause of thickness unevenness peculiar to multilayer lamination together with the thickness unevenness reducing technology. is there. In the melt flow process for forming the laminated film of the present invention, when the flow path suddenly expands in the width direction or the longitudinal direction in the laminated state, the polyester A and the polyester B are laminated in the width direction, the longitudinal direction, or the thickness direction. There occurs a portion where the ratio is not uniform or a phenomenon that the laminated thickness is not uniform in the width direction. For this reason, it is preferable to make the expansion angle of a flow path 30 degrees or less. By doing in this way, not only the thickness nonuniformity deterioration of an unstretched film can be suppressed, but the thickness nonuniformity deterioration in the subsequent extending process can be significantly suppressed. On the other hand, in order to obtain higher tear strength in the biaxially stretched laminated film of the present invention, heat treatment is preferably performed at a temperature of 110 ° C. or higher and 200 ° C. or lower. When the relaxation treatment is performed to maintain the thickness, there is a problem that the thickness unevenness deteriorates as the flatness deteriorates. In order to suppress deterioration of thickness unevenness due to this, in the present invention, after heat treatment at 110 ° C. or more and 200 ° C. or less, and after relaxation treatment of 3% or more and 15% or less at the same temperature, among polyester A and polyester B, having a lower glass transition temperature of the polyester (glass transition temperature +10) ° C. or higher (the glass transition temperature +30) ° C. that cool slowly over 5 seconds or less. By using these methods in combination, it becomes easy to make the thickness unevenness 3% or less. Moreover, by doing in this way, it becomes easy to make the thermal contraction rate in 100 degreeC of a film longitudinal direction and the width direction into 1.5% or less. Furthermore, in order to make the thermal shrinkage rate even 1.0%, it is preferable to perform a relaxation treatment of 5% or more.

  Further, the polyester or copolymer polyester of the present invention preferably has a tensile modulus of 1.4 GPa or higher, and as such a resin, a resin having a glass transition temperature of 50 ° C. or higher is preferably used.

  The biaxially stretched laminated film of the present invention preferably has a tear strength of 50 N / mm or more in the longitudinal direction and the width direction of the film. In order to obtain such a film, each of the polyester A and the polyester B is used. It is necessary to increase the number of layers to 2 or more. Moreover, in order to set it to 60 N / mm or more, it is preferable that the layer which consists of polyester which has a soft polyester or a bulky skeleton is included, but in the case of a flexible polyester, since an internal haze tends to become high, this book In the invention, it is not so preferable. Moreover, in order to set it as 80 N / mm or more, it is preferable to laminate | stack with the same high lamination precision as the method of reducing the above-mentioned interference fringe.

  In the biaxially stretched laminated film of the present invention, the Young's modulus in the longitudinal direction and the width direction of the film is preferably 3 GPa or more. In order to achieve this, polyethylene terephthalate and / or polyethylene naphthalate is used as a main component. The ratio of the layer thickness to the total film thickness is preferably 50% or more. Moreover, in order to set it as 3.5 GPa or more, it is preferable to extend | stretch 10 times or more by area magnification.

An evaluation method of physical property values used in the present invention will be described.
(Method for evaluating physical properties)
(1) Tear Strength Tear strength (N) was measured based on JIS K 7128-2 (1998) (Elmendorf Tear Method) using a tear tester (manufactured by Toyo Seiki) with a maximum load of 64N. The measured value was divided by the measured film thickness to obtain the tear strength mN / μm. The tear strength was obtained by averaging the test results of 20 samples in the vertical direction and the horizontal direction. In addition, when it was not torn substantially, it calculated as 64N as an overrange.

(2) Internal haze Internal haze was measured using HGM-2DP by Suga Test Instruments Co., Ltd. The film was immersed in a tetralin solution, and the internal haze was determined from the following formula from the diffuse transmittance and the total light transmittance.
Internal haze (%) = diffuse transmittance / total light transmittance × 100
(3) Visible light transmittance The light transmittance was measured using a Hitachi spectrophotometer (U-3410 Spectrophotometer). The detection speed is 600 nm / min. It was. For visible light transmittance, a wavelength range of 400 nm to 800 nm was measured.

(4) Unevenness of thickness The film was sampled to a width of 30 mm and a length of 1 m. At this time, the target measurement direction (longitudinal direction or width direction) was made to coincide with the direction in which the length was 1 m. For the measurement, the thickness of the film is continuously measured using a film thickness tester “KG601A” and an electronic micrometer “K306C” manufactured by Anritsu Corporation. The conveyance speed of the film was 1.5 m / min. R = Tmax−Tmin is obtained from the maximum thickness value Tmax (μm) and the minimum value Tmin (μm) at a length of 1 m, and thickness unevenness (%) is calculated from R and the average thickness Tave (μm) of 1 m length = R / Tave × 100. As sought. The thickness unevenness was an average value of 10 measurements.

(5) Young's modulus The Young's modulus (tensile modulus) of the biaxially stretched laminated film was measured according to ASTM test method D882-88. The Young's modulus (tensile modulus) of polyester A and polyester B is determined by extruding each polymer in a single film state, rapidly cooling and solidifying on a casting drum controlled at a temperature of 25 ° C., and using an electrostatic application device. The unstretched film obtained by improving the adhesiveness of the film was carried out in the same manner. The measurement was performed using an Instron type tensile tester (Orientec Co., Ltd. film strong elongation automatic measuring device “Tensilon AMF / RTA-100”). A sample film having a width of 10 mm was pulled under conditions of 100 mm between test lengths and a pulling speed of 200 mm / min, and the tensile elastic modulus was determined. In addition, n number was 10 times and the average value was employ | adopted.

(6) Heat Shrinkage A sample piece of 300 mm × 10 mm was prepared, and at this time, the long axis of the sample piece was made to coincide with the film longitudinal direction and the width direction to be measured. This sample piece is left in an atmosphere of 23 ° C. and 60% RH for 30 minutes, and in that atmosphere, two marks are made at intervals of about 200 mm in the longitudinal direction of the film, and the mark is measured using a linear scale measuring instrument. Was measured, and the value thereof was designated as A. Next, the sample is allowed to stand for 30 minutes in an atmosphere of 100 ° C. in a tension-free state, then cooled for 1 hour in an atmosphere of 23 ° C. and 60% RH, and after humidity adjustment, the interval between the marks applied is measured. This was designated B. At this time, the thermal contraction rate was calculated from the following equation. The n number was 3 and the average value was adopted.
Thermal contraction rate (%) = 100 × (A−B) / A.

(7) Ultraviolet transmittance The light transmittance was measured using a Hitachi spectrophotometer (U-3410 Spectrophotometer). The detection speed is 600 nm / min. It was. The ultraviolet transmittance was obtained by averaging the transmittance every 10 nm in the wavelength range of 190 nm to 370 nm.

(8) Intrinsic viscosity A value calculated from the following equation from the solution viscosity measured at 25 ° C in orthochlorophenol was used. That is, ηsp / C = [η] + k [η] ² · C. Here, ηsp = (solution viscosity / solvent viscosity) −1, C is the amount of dissolved polymer per 100 ml of solvent (g / 100 ml), and K is the Huggins constant (0.343). The solution viscosity and the solvent viscosity were measured with an Ostwald viscometer.

(9) Appearance Appearance abnormalities when using laminated glass were visually determined. Appearance abnormalities were inspected in a dark room with a hand-held fluorescent lamp over the observation side. ◎ When there is almost no interference unevenness and it does not appear cloudy, ○ when there is slight interference unevenness, interference unevenness is clearly present, the whole is colored, or the flatness of the inner interlayer film is poor A case where the film appeared to be cloudy or clouded was marked with x.

(10) Security performance Compliant with European standard EN356. Detailed conditions are as follows.
Steel balls used: Diameter 100mm, weight 4.1kg
Falling method: Falling in turn to each vertex of a regular triangle with a side of 130 mm near the center.
Test sample size: 900mm x 1100mm
Judgment standard:
P1A Steel ball drop height 1.5m Dropped once on each vertex and does not penetrate P2A Steel ball fall height 3.0m Dropped once on each vertex and do not penetrate P3A Steel ball fall height 0m Falling once on each vertex and not penetrating P4A steel ball falling height 9.0m Dropping once on each vertex and not penetrating P5A steel ball falling height 9.0m Dropping once on each vertex This was repeated three times and did not penetrate. In addition, the passed standards were described in the results of the examples.

Example 1
As polyester A, polyethylene terephthalate (PET) having a glass transition temperature of 80 ° C. and an intrinsic viscosity of 0.65 was used. As polyester B, copolymerized polyethylene terephthalate having a glass transition temperature of 80 ° C. and an intrinsic viscosity of 0.75 obtained by copolymerizing 25 mol% of 1,4-cyclohexanedimethanol with respect to ethylene glycol was used. These polyesters A and B were dried and then fed to an extruder. The tensile modulus of polyester A was 1.8 GPa, and the tensile modulus of polyester B was 1.8 GPa.

  Polyesters A and B were each melted at 280 ° C. with an extruder, passed through a gear pump and a filter, and then joined in a feed block having a wall surface roughness of 0.2 S. Polyester B has a structure in which eight layers are laminated alternately in the thickness direction, and both surface layer portions are polyester A. Here, the discharge amount was adjusted so that the lamination thickness ratio was A / B = 13.

  The laminate consisting of 17 layers thus obtained was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying electrostatic force. The obtained cast film was heated with a roll group set at 90 ° C., stretched 3.0 times in the longitudinal direction, and then subjected to corona discharge treatment in air on both sides of the uniaxially stretched film, and the wetting tension of the base film 55 mN / m, and the treated surface is coated with a laminated film coating solution composed of (polyester resin with a glass transition temperature of 18 ° C.) / (Polyester resin with a glass transition temperature of 82 ° C.) / Silica particles with an average particle size of 100 nm. Then, a transparent, easy-slip, and easy-adhesion layer was formed.

  This uniaxially stretched film was guided to a tenter, preheated with hot air at 100 ° C., and then stretched 3.3 times in the transverse direction. The stretched film is directly heat-treated in a tenter with hot air at 160 ° C., then subjected to a relaxation treatment of 7% in the width direction at the same temperature, and then treated in an atmosphere at 100 ° C. for 7 seconds. Then, it was gradually cooled to room temperature and wound up. The thickness of the obtained film was 100 μm. Moreover, the average thickness of the layer which consists of polyester A was 10.5 micrometers, and the average thickness of the layer which consists of polyester B was 0.8 micrometer. Here, the refractive index of each layer was assumed to be 1.65 for the polyester A layer and 1.60 for the polyester B layer.

Next, two float glass plates having a thickness of 3 mm and dimensions of 1100 mm × 900 mm were made to face each other, and the following three intermediate films having the same dimensions as the glass plates were overlapped and inserted between the glass plates.
First intermediate film: ethylene vinyl acetate copolymer (S-LEC EN Film 0.4 mm manufactured by Sekisui Chemical)
Second intermediate film: Polyester film (0.1 mm) formed as described above
Third interlayer film: ethylene vinyl acetate copolymer (S-LEC EN Film 0.4 mm, manufactured by Sekisui Chemical)
The glass plate into which the intermediate film was inserted was thermocompression bonded under the conditions of 700 mmHg and 100 ° C. to obtain a laminated glass. The obtained results are shown in Table 1.

(Example 2)
As a laminating apparatus, a 9-layer feed block with a wall surface roughness of 0.2 S and a square mixer were used, and after heat treatment at 160 ° C. and relaxation treatment, treatment was performed in an atmosphere at 100 ° C. for 4 seconds. Except for the above, a polyester film was formed in the same manner as in Example 1. The obtained results are shown in Table 1.

(Example 3)
In Example 1, a polyester film was formed in the same manner as in Example 1 except that the number of laminated layers was 43 and the film thickness was 250 μm. The obtained results are shown in Table 1.

Example 4
The conditions were the same as in Example 3 except that the following nine intermediate films were inserted. The obtained results are shown in Table 1.
First intermediate film: ethylene vinyl acetate copolymer (S-LEC EN Film 0.4 mm manufactured by Sekisui Chemical)
Second intermediate film: Polyester film (0.25 mm) formed as described above
Third interlayer film: ethylene vinyl acetate copolymer (S-LEC EN Film 0.4 mm, manufactured by Sekisui Chemical)
Fourth intermediate film: Polyester film (0.25 mm) formed as described above
Fifth interlayer film: ethylene vinyl acetate copolymer (S-LEC EN Film 0.4 mm, manufactured by Sekisui Chemical)
Sixth intermediate film: polyester film (0.25 mm) formed as described above
Seventh intermediate film: ethylene vinyl acetate copolymer (Sekisui Chemical S-LEC EN Fi eighth intermediate film: polyester film formed as described above (0.25 mm)
Ninth intermediate film: ethylene vinyl acetate copolymer (S-LEC EN Film 0.4 mm, manufactured by Sekisui Chemical)
( Reference Example 1 )
As polyester A, polyethylene terephthalate (PET) having a glass transition temperature of 80 ° C. and an intrinsic viscosity of 0.65 was used. As polyester B, copolymerized polyethylene terephthalate having a glass transition temperature of 80 ° C. and an intrinsic viscosity of 0.75 obtained by copolymerizing 25 mol% of 1,4-cyclohexanedimethanol with respect to ethylene glycol was used. These polyesters A and B were dried and then fed to an extruder. The tensile modulus of polyester A was 1.8 GPa, and the tensile modulus of polyester B was 1.8 GPa.

  Polyesters A and B were each melted at 280 ° C. with an extruder, passed through a gear pump and a filter, and joined at a feed block having a wall surface roughness of 0.2 S. Polyester B has a structure in which 100 layers are alternately laminated in the thickness direction, and both surface layer portions are polyester A. Here, the discharge amount was adjusted so that the lamination thickness ratio was A / B = 13.

  The laminate consisting of 201 layers thus obtained was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum kept at a surface temperature of 25 ° C. while applying electrostatic force. The obtained cast film was heated with a roll group set at 90 ° C., stretched 3.0 times in the longitudinal direction, and then subjected to corona discharge treatment in air on both sides of the uniaxially stretched film, and the wetting tension of the base film 55 mN / m, and the treated surface is coated with a laminated film coating solution composed of (polyester resin with a glass transition temperature of 18 ° C.) / (Polyester resin with a glass transition temperature of 82 ° C.) / Silica particles with an average particle size of 100 nm. Then, a transparent, easy-slip, and easy-adhesion layer was formed.

  This uniaxially stretched film was guided to a tenter, preheated with hot air at 100 ° C., and then stretched 3.3 times in the transverse direction. The stretched film is directly heat-treated in a tenter with hot air of 230 ° C., and then subjected to a relaxation treatment of 7% in the width direction at the same temperature, and then treated in an atmosphere of 100 ° C. for 7 seconds. Then, it was gradually cooled to room temperature and wound up. The thickness of the obtained film was 600 μm. Moreover, the average thickness of the layer which consists of polyester A was 5.5 micrometers, and the average thickness of the layer which consists of polyester B was 0.47 micrometer. Here, the refractive index of each layer was assumed to be 1.65 for the polyester A layer and 1.60 for the polyester B layer.

Next, two float glass plates having a thickness of 2.0 mm and dimensions of 1100 mm × 900 mm were opposed to each other, and the following three interlayer films having the same dimensions as the glass plates were overlapped and inserted between the glass plates.
First intermediate film: ethylene vinyl acetate copolymer (S-LEC EN Film 0.15 mm, manufactured by Sekisui Chemical)
Second intermediate film: polyester film (0.6 mm) formed as described above
Third interlayer film: ethylene vinyl acetate copolymer (S-LEC EN Film 0.15 mm, manufactured by Sekisui Chemical)
The glass plate into which the intermediate film was inserted was thermocompression bonded under the conditions of 700 mmHg and 100 ° C. to obtain a laminated glass. The obtained results are shown in Table 1.

( Reference Example 2 )
A laminated film was formed under the same apparatus and conditions as in Reference Example 1 except that the film forming speed and the discharge amount were adjusted to make the film thickness 800 μm. In the obtained film, the average thickness of the layer made of polyester A was 7.4 μm, and the average thickness of the layer made of polyester B was 0.62 μm. A laminated glass was prepared using the same materials and conditions as in Reference Example 1 except that the obtained laminated film was used as the second intermediate film and the glass thickness was changed to 2.7 mm. The obtained results are shown in Table 1.

( Reference Example 3 )
A laminated film was formed under the same apparatus and conditions as in Reference Example 1 except that the film forming speed and the discharge amount were adjusted to set the film thickness to 1200 μm. In the obtained film, the average thickness of the layer made of polyester A was 11 μm, and the average thickness of the layer made of polyester B was 0.92 μm. A laminated glass was prepared using the same materials and conditions as in Reference Example 1 except that the obtained laminated film was used as the second intermediate film and the glass thickness was changed to 2.7 mm. The obtained results are shown in Table 1.

(Example 5 )
A film was formed under the same apparatus and conditions as in Reference Example 1 except that the heat treatment temperature after biaxial stretching was 160 ° C. The obtained results are shown in Table 2.

(Comparative Example 1)
As polyester A, polyethylene terephthalate (PET) having a glass transition temperature of 80 ° C. and an intrinsic viscosity of 0.65 was used. And it film-formed on the same conditions as Example 1 except having set it as the conditions which form a single layer film using this. Moreover, the laminated glass was created similarly to Example 1. FIG. The obtained results are shown in Table 2.

(Comparative Example 2)
In Comparative Example 1, a film was formed under the same conditions except that the film thickness was 250 μm. Moreover, the laminated glass was created on the conditions of Example 4 using the obtained single layer polyester film. The obtained results are shown in Table 2.

(Comparative Example 3)
Film formation under the same conditions as in Example 1 except that a 151 layer feed block having a wall surface roughness of 0.2S and a square mixer were used as the laminating apparatus, and the laminating thickness ratio was 1/1. A polyester film was obtained. Moreover, the laminated glass was created similarly to Example 1 using the obtained polyester film. The obtained results are shown in Table 2.

(Comparative Example 4)
A polyester film was formed under the same conditions as in Example 1. However, the following points were changed. First, a three-layer feed block having a wall surface roughness of 2.0 S and a square mixer were used as a laminating apparatus. In addition, the longitudinal stretching ratio was 2.6 times, and the film after uniaxial stretching was coated with a layered film coating liquid composed of acrylic resin / silica particles having an average particle size of 100 nm to form a transparent, easy-sliding and easy-adhesive layer. . Further, after heat treatment and relaxation treatment at 160 ° C., it was gradually cooled at room temperature. A laminated glass was produced in the same manner as in Example 1 using the obtained polyester film. The obtained results are shown in Table 2.

(Comparative Example 5)
A polyester film was formed under the same conditions as in Example 1. However, as polyester B, a copolymerized polyethylene terephthalate copolymerized with 40 mol% of sebacic acid with respect to terephthalic acid and having a glass transition temperature of 0 ° C. and an intrinsic viscosity of 0.70 was used. The Young's modulus of this polyester was 0.1 GPa. The obtained results are shown in Table 2.

  The present invention can be applied not only to the security laminated glass and decorative security laminated glass, but also to bulletproof glass and shatterproof glass, but the application range is not limited thereto.

Claims (12)

A film having at least a layer made of polyester A and a layer made of polyester B, each having two or more layers, the internal haze being 1.5% or less, and the maximum light transmittance in the visible light region The biaxially stretched laminated film is characterized in that the difference between the value and the minimum value is 12% or less, and the thickness unevenness in the longitudinal direction and the width direction of the film is 6% or less. Heat treatment and relaxation treatment of 3% or more and 15% or less at the same temperature, polyester (A) and polyester (B) having a lower glass transition temperature (glass transition temperature +10) ° C. or more (glass transition temperature +30) ) A biaxially stretched laminated film obtained by annealing at 5 ° C or lower for 5 seconds or less .
  The biaxially stretched laminated film according to claim 1, wherein the tear strength in the longitudinal direction and the width direction of the film is 50 N / mm or more.   The biaxially stretched laminated film according to claim 1 or 2, wherein the Young's modulus in the longitudinal direction and the width direction of the film is 3 GPa or more.   The biaxially stretched laminated film according to any one of claims 1 to 3, wherein the Young's modulus of polyester A and polyester B is 1.4 GPa or more.   The biaxially stretched laminated film according to any one of claims 1 to 4, wherein a heat shrinkage rate at 100 ° C in a film longitudinal direction and a width direction is 1.5% or less.   The biaxially stretched laminated film according to any one of claims 1 to 5, wherein a film thickness is 50 µm or more and 1100 µm or less.   A film for laminated glass comprising the biaxially stretched laminated film according to any one of claims 1 to 6.   A laminated glass comprising the laminated glass film according to claim 7 and glass.   A laminated glass comprising the film for laminated glass according to claim 7, a film made of polyvinyl butyral and / or a film made of an ethylene-vinyl acetate copolymer, and glass.   A laminated glass comprising an laminated film in which an ethylene-vinyl acetate copolymer is disposed on both front and back sides of the film for laminated glass according to claim 7 as an intermediate film between two glass plates.   The laminated glass according to claim 9 or 10, wherein the ultraviolet transmittance of the ethylene-vinyl acetate film is 5% or less.   The laminated glass according to any one of claims 8 to 11, wherein the thickness is 4600 µm or more and 6700 µm or less.