JP5410919B2 - Biaxially oriented multilayer laminate film and laminate - Google Patents

Description

  The present invention relates to a biaxially oriented multilayer laminated film using a hydrophobic resin having a water absorption of 0.1% by weight or less and an aromatic polyester, and a laminate using the same.

  Aromatic polyesters typified by polyethylene terephthalate and polyethylene-2,6-naphthalate have excellent mechanical properties, dimensional stability and heat resistance, and thus are widely used for films and the like. In particular, polyethylene-2,6-naphthalate has mechanical properties, dimensional stability, and heat resistance superior to those of polyethylene terephthalate, so that it is used in demanding applications such as a base film for high-density magnetic recording media. It is used. However, the demand for dimensional stability in high-density magnetic recording media and the like in recent years is increasing, and further improvement of characteristics is required.

  Therefore, Patent Document 1 proposes blending or laminating a polyolefin such as syndiotactic polystyrene and a polyester such as polyethylene-2,6-naphthalenedicarboxylate. However, the blend has a problem that the surface of the obtained film is likely to be rough because the compatibility is poor, and on the other hand, the laminated film such as two layers is likely to be curled. On the other hand, Patent Document 1 also discloses a multilayer laminated film in which polyolefin and polyester are alternately laminated. With this multilayer laminated film, there is no problem that the surface of the film becomes rough or the film itself is curled.

  However, as is clear from the layer structure, the film has one surface and the other surface that have almost the same surface, so that the film can be wound when used as a base film such as a magnetic recording tape. It was difficult to achieve a high degree of compatibility between the electromagnetic conversion characteristics of the magnetic recording tape and the magnetic recording tape.

  Moreover, the method (patent documents 2-5 etc.) which provides layers (M layer), such as a metal, on the single side | surface or both surfaces of a polyester film is disclosed. However, if the thickness of the M layer is increased for dimensional stability, such as by reducing the humidity expansion coefficient, cracks are likely to occur in the M layer, and there is a limit to the improvement by the M layer alone.

International Publication No. 2005/073318 Pamphlet JP 2003-30818 A JP 2005-196944 A JP 2006-277920 A JP 2003-242630 A

  An object of the present invention is to provide a biaxially oriented multilayer laminated film capable of achieving both excellent dimensional stability against changes in humidity, surface properties and winding properties, and a laminate using the same.

  As a result of diligent research to solve the above problems, the inventors of the present invention set one surface of the multilayer laminated film to have a surface roughness in the range of 0.5 to 5 nm, and the other surface has a surface roughness of 1 nm or more. The inventors found that by increasing the size, both the desired surface property and winding property can be obtained, and the present invention has been achieved.

Thus, according to the present invention, the film layer (A) made of the aromatic polyester (A) and the film layer (B) made of the hydrophobic resin (B) having a water absorption of 0.1% or less are alternately 11 or more layers. A biaxially oriented multilayer laminated film having a laminated structure in which one surface roughness (RaX) is in the range of 0.5-5 nm and the other surface roughness (RaY) is 1 nm or more larger than RaX, and 10nm Ri der hereinafter either the film layer of the film layer a or B forms both of the two outermost layer side of the film layer not forming the outermost surface layer has an average particle diameter 0.01-1.0μm The particles on the side forming the outermost layer do not contain inert particles, or particles having a smaller average particle size than the film layer on the side not forming the outermost layer. Contain the same average grain The thickness (tX) of the film layer forming the outermost layer having a small surface roughness and the outermost layer having a small surface roughness is the thickness (tY) of the film layer forming the outermost layer having a large surface roughness. A biaxially oriented multilayer laminated film that is 1.5 times or more of the thickness is provided.

Moreover, according to this invention, the film layer (A) which consists of aromatic polyester (A), and the film layer (B) which consists of hydrophobic resin (B) whose water absorption is 0.1% or less are alternately 11 layers. A biaxially oriented multilayer laminated film having a laminated structure as described above, wherein one surface roughness (RaX) is in the range of 0.5-5 nm and the other surface roughness (RaY) is 1 nm or more larger than RaX. And the film layer of either one of the film layers A and B forms the outermost layer having a large surface roughness, and 0.001 inactive particles having an average particle size of 0.01 to 1.0 μm. The film layer on the side containing −5% by weight and not forming the outermost layer having a large surface roughness forms the outermost layer having a small surface roughness and does not contain inert particles, or the outermost layer having a large surface roughness. Average grain than the film layer on the forming side Or containing small particles of a biaxially oriented multi-layer laminate film containing the inert particles having the same average particle diameter with less content than B is provided. In addition, as a preferred embodiment, the thickness of the outermost layer having a small surface roughness (tX (nm)), the thickness of the outermost layer having a large surface roughness (tY (nm)), and a film adjacent to the outermost layer having a small surface roughness. The thickness of the layer (tX ′ (nm)) and the thickness of the film layer (tY ′ (nm)) adjacent to the outermost layer having a large surface roughness are expressed by the following relational expression (formula 1) tX> 1.5 × tX ′
(Formula 2) tY> 1.5 × tY ′
A biaxially oriented multilayer laminated film satisfying at least one of the above is also provided. Furthermore , according to the present invention, the film layers (A) made of the aromatic polyester (A) and the film layers (B) made of the hydrophobic resin (B) having a water absorption of 0.1% or less are alternately 11 A biaxially oriented multilayer laminated film having a laminated structure in which one or more layers are laminated, wherein one surface roughness (RaX) is in the range of 0.5-5 nm and the other surface roughness (RaY) is 1 nm or more than RaX. The outermost layer having a large surface roughness of the biaxially oriented laminated polyester film that is large and 10 nm or less contains 0.001-5 wt% of inert particles having an average particle size of 0.01-1.0 μm. Film layers A and B, which are composed of layers (C layer) and form a laminated structure, contain no inert particles or particles having a smaller average particle size than the film layer forming the outermost layer having the large surface roughness. Of the same average particle size Biaxially oriented multilayer laminate film containing a smaller amount of the active particles are also provided. Moreover, as a preferable aspect of the present invention, at least one outermost layer of the biaxially oriented laminated polyester film is a coating layer (fourth layer, D layer) having inert particles, film layer A and film layer B. Does not contain inert particles, the hydrophobic resin (B) is a styrene polymer having a syndiotactic structure, the hydrophobic resin (B) is polyphenylene sulfide, and the hydrophobic resin (B) It is a cycloolefin, the Young's modulus in the film forming direction and the width direction of each film is 4.5 GPa or more, and the humidity expansion coefficient in the width direction of the film is 0.1 × 10 ^{−6 to} 9 × 10 ⁻⁶ / it% is RH, the temperature expansion coefficient in the width direction of the film is ^{-10 × 10 -6 ~10 × 10 -6} / ℃, the thickness of the film is in the range of 1-10μm When biaxially oriented multi-layer laminated film, the biaxially oriented multi-layer laminate film comprising at least one of that used for the base film of the magnetic recording medium it is also provided.

  Furthermore, according to the present invention, the biaxially oriented multilayer laminated film of the present invention is further provided with a layer (M layer) made of a metal or a metal-based inorganic compound on one or both sides, and further dimensional stability against environmental changes. There is also provided a laminate having a higher height, particularly a laminate used for a base film of a magnetic recording medium.

ADVANTAGE OF THE INVENTION According to this invention, the dimensional change with respect to a humidity change is very small, the surface is flat, and the biaxially oriented multilayer laminated film with favorable winding property is provided.
Therefore, if the biaxially oriented multilayer laminated film of the present invention is used, a high-density magnetic recording medium having excellent dimensional stability against changes in humidity can be efficiently provided.

  In addition, according to the present invention, by providing a layer (M layer) such as a metal on one or both sides of the biaxially oriented multilayer laminate film, a laminate with further improved dimensional stability against environmental changes can be provided, If it is used particularly as a base film of a magnetic recording medium, a high-density magnetic recording medium having excellent dimensional stability against changes in humidity can be efficiently provided.

<Hydrophobic resin (B)>
Examples of the hydrophobic resin (B) in the present invention include aliphatic (including alicyclic) or aromatic polyolefin, liquid crystalline polyester, polyether ether ketone, polyphenylene sulfide and the like. Among these, resins with syndiotactic structure such as polystyrene, cycloolefin polymer, polyphenylene sulfide, etc. have excellent mechanical properties while improving the dimensional stability against changes in temperature and humidity of the resulting biaxially oriented multilayer laminated film. Etc. are preferable because they are easily expressed.

As a specific polystyrene having a syndiotactic structure, the stereochemical structure is a polystyrene having a syndiotactic structure, and the tacticity measured by a nuclear magnetic resonance method ( ¹³ C-NMR method) is dyad (structural unit). 2) is 75% or more, preferably 85% or more, and pentad (5 structural units) is 30% or more, preferably 50% or more.

  Examples of such SPS include polystyrene, poly (alkyl styrene), poly (methyl styrene), poly (ethyl styrene), poly (propyl styrene), and poly (butyl styrene). Among these, polystyrene, poly (p -Methylstyrene), poly (m-methylstyrene), and poly (p-tertiarybutylstyrene) are preferably exemplified. SPS has a number average molecular weight of 10,000 or more, preferably 50,000 or more. When the number average molecular weight is less than the lower limit, heat resistance and mechanical properties are insufficient. On the other hand, the upper limit of the number average molecular weight is preferably 500,000 or less. When this upper limit is exceeded, film-forming property may become poor.

  Specific examples of the cycloolefin polymer include norbornene-based polycycloolefins. The product names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, and the product name “ARTON” manufactured by JSR Corporation. ", Trade name" TOPAS "manufactured by Polyplastics Co., Ltd. and the like.

  Furthermore, specific polyphenylene sulfide refers to a polymer in which 80 mol% or more, preferably 90 mol% or more of repeating units are composed of structural units represented by the following general formula.

  If the polymer component composed of the structural unit represented by the above general formula is less than 80 mol%, the crystallinity, softening point, etc. of the polymer are lowered, and the heat resistance, dimensional stability and mechanical properties of the resulting film are impaired. If the repeating unit is less than 20 mol%, preferably less than 10 mol%, a unit containing a copolymerizable sulfide bond may be contained. The copolymerization method of the polymer may be random or block.

Among these hydrophobic resins (B), polystyrene, polyphenylene sulfide, and cycloolefin polymers having a syndiotactic structure are particularly preferable.
These hydrophobic resins (B) can be produced by a method known per se.

<Aromatic polyester (A)>
The aromatic polyester (A) in the present invention has a Tg (glass transition temperature) in DSC of 70 ° C. or higher, more preferably 95 ° C. or higher, particularly 110 ° C. or higher when viewed as a polyester resin composition constituting the film layer (A). Preferably there is. The upper limit of the glass transition temperature of the preferred aromatic polyester (A) is not particularly limited, but is preferably 170 ° C. or lower, more preferably 150 ° C. or lower from the viewpoint of film forming properties when laminated with the film layer (B).

  From such a point, as a specific aromatic polyester (A), polyethylene-2,6-naphthalene dicarboxylate having 95% by mole or more of repeating units composed of ethylene-2,6-naphthalene dicarboxylate is the most. Preferably, a component capable of further increasing Tg may be copolymerized or blended. By the way, the aromatic polyester (A) may be polyethylene terephthalate whose main repeating unit is ethylene terephthalate. However, in the case of polyethylene terephthalate, unlike the above-mentioned polyethylene-2,6-naphthalenedicarboxylate, Tg tends to be low only by making it a homopolymer, and a copolymerization component capable of increasing the glass transition temperature is copolymerized, It is preferable to blend polyetherimide or a liquid crystal resin (see, for example, JP-A Nos. 2000-355631, 2000-141475, and 11-11568). The aromatic polyester (A) in the present invention has a melting point measured by DSC in the range of 240 to 300 ° C., further in the range of 250 to 290 ° C., particularly in the range of 260 to 280 ° C. preferable. If the melting point exceeds the above upper limit, the melt viscosity is large at low temperatures, and the fluidity is poor when molding by extrusion, and the layer thickness structure tends to become non-uniform. As a result, the film-forming property tends to decrease. On the other hand, when it is less than the above lower limit, although the film forming property is excellent, the elongation suppressing effect at the time of processing tends to be insufficient.

  In addition, from the viewpoint of further improving the dimensional stability against changes in temperature and humidity, it is a polymer obtained by copolymerization of 6,6 ′-(alkylenedioxy) di-2-naphthoic acid mentioned in International Publication No. 2008/153188 pamphlet and the like. Also good.

<Biaxially oriented multilayer laminated film>
The biaxially oriented multilayer laminated film of the present invention has a laminated structure in which 11 or more film layers (A) and film layers (B) are alternately laminated as described above. The preferred number of layers is the total number of layers of the film layer (A) and the film layer (B), the lower limit being 15 or more, further 21 or more, particularly 31 or more, most preferably 41 or more, and the other upper limit is 10001 or less, further 1001 or less. It is preferable from the point of the uniformity of a layer structure and the expression of an effect that it exists in the range. When the number of layers is less than the lower limit, it is difficult to suppress the occurrence of curling, the film stretching characteristics deteriorate and the molecular chains are difficult to align, and it is difficult to produce a film having a desired humidity expansion coefficient. There is a case. The upper limit of the number of stacked layers is not particularly limited, but is preferably 10001 or less from the viewpoint of easily maintaining the stacked structure.

  Of course, other film layers may be laminated or a coating layer may be provided as long as the effects of the present invention are not impaired. The film layer (B) preferably has a large volume fraction in the film from the viewpoint of further improving the dimensional stability against environmental changes. From such a viewpoint, in the biaxially oriented multilayer laminated film of the present invention, the total thickness of the film layer (B) is 10% or more, more preferably 20% or more, with respect to the thickness of the biaxially oriented multilayer laminated film. 30% or more, more preferably 50% or more, particularly 55% or more, and most preferably 60% or more. On the other hand, the upper limit is 95% or less, further 90% or less, further 85% or less, particularly 80%. It is preferable to be in the following range. By setting it as such a range, the dimensional stability improvement effect with respect to a humidity change and the elongation inhibitory effect at the time of a process can be expressed more highly. If it is less than the lower limit, the effect of reducing the humidity expansion coefficient tends to be poor, and if it exceeds the other upper limit, the effect of suppressing elongation at the time of processing by the film layer (A) tends to be poor.

  In the biaxially oriented multilayer laminated film of the present invention, one surface roughness (RaX) is in the range of 0.5-5 nm, and the other surface roughness (RaY) is 1 nm or more larger than RaX and 10 nm or less. There is a need. When RaX is smaller than 0.5 nm, the slipping property is deteriorated and the winding property is deteriorated. If the thickness exceeds 5 nm, the electromagnetic conversion characteristics deteriorate when the magnetic tape is used. A more preferable range of RaX is 1-4 nm, and more preferably 1.5-3 nm. If RaY is not larger than RaX by 1 nm or more, the surface becomes too flat and the winding property deteriorates. On the other hand, when it exceeds 10 nm, the magnetic tape is transferred to the surface of the magnetic layer. It causes deterioration of electromagnetic conversion characteristics and error rate. A more preferable range of RaY is 2-9 nm, more preferably 3-8 nm, and particularly preferably 4-7 nm.

  Usually, in order to increase the surface roughness of the film, the film layer may contain inert particles to form protrusions. As the inert particles to be contained, (1) heat resistant polymer particles (for example, crosslinked silicone resin, crosslinked polystyrene, crosslinked acrylic resin, melamine-formaldehyde resin, aromatic polyamide resin, polyimide resin, polyamideimide resin, crosslinked polyester, etc.) Particles), (2) metal oxides (eg, aluminum oxide, titanium dioxide, silicon dioxide (silica), magnesium oxide, zinc oxide, zirconium oxide, etc.), metal carbonates (eg, magnesium carbonate, calcium carbonate, etc.) Particles made of inorganic compounds such as metal sulfates (eg calcium sulfate, barium sulfate etc.), carbon (eg carbon black, graphite, diamond etc.) and clay minerals (eg kaolin, clay, bentonite etc.) And more (3) and the like inside precipitated particles formed by precipitation, such as externally added particles are added in the form of composite particles such as particles, such as different materials shell type using for example the core and the shell or (4) a catalyst. Among these, at least one kind of particles selected from the group consisting of a crosslinked silicone resin, a crosslinked acrylic resin, a crosslinked polyester, a crosslinked polystyrene, aluminum oxide, titanium dioxide, silicon dioxide, kaolin and clay is particularly preferable. At least one kind of particles selected from the group consisting of silicone resin, cross-linked acrylic resin, cross-linked polyester, cross-linked polystyrene, and silicon dioxide (excluding porous silica etc.) reduces the variation in particle size. It is preferable because it is easy. Of course, these may be used in combination of two or more.

  However, it is difficult to satisfy such surface roughness only with the film layers A and B forming the above-described laminated structure simply by containing inert particles in one film layer. Therefore, the preferred layer structure of the film will be described in detail.

  First, as the first layer configuration, one of the film layers A and B forms both of the two outermost layers, that is, when the total of the film layers A and B is an odd number layer, The film layer on the non-forming side contains 0.001 to 5% by weight of inert particles having an average particle size of 0.01 to 1.0 μm, and the film layer on the side forming the outermost layer does not contain inert particles, or Contains particles with a smaller average grain size than the film layer on the side that does not form the outermost layer, or contains inert particles with the same average particle size at a lower content, and forms the outermost layer with a smaller surface roughness. The thickness (tX) of the film layer is preferably 1.5 times or more with respect to the thickness (tY) of the film layer forming the outermost layer having a large surface roughness. By making tX 1.5 times or more as compared with tY, it is possible to suppress the influence of inert particles present in the inner film layer, and to adjust the outermost layer having a small surface roughness more flatly.

Next, with respect to the second layer structure, the outermost layers are formed by the film layers A and B, that is, the total of the film layers A and B is an even layer, and either the film layer A or B film The layer forms the outermost layer having a large surface roughness and contains 0.001 to 5% by weight of inert particles having an average particle size of 0.01 to 1.0 μm and does not form the outermost layer having a large surface roughness. Whether the film layer forms the outermost layer having a small surface roughness and does not contain inert particles, or contains particles having a smaller average particle size than the film layer on the side forming the outermost layer having a large surface roughness It is preferable to contain inert particles having the same average particle size in a smaller content than B. At this time, the thickness (tX (nm)) of the outermost layer having a small surface roughness, the thickness (tY (nm)) of the outermost layer having a large surface roughness, and the thickness of the film layer adjacent to the outermost layer having a small surface roughness ( tX ′ (nm)) and the thickness (tY ′ (nm)) of the film layer adjacent to the outermost layer having a large surface roughness satisfy at least one of the following relational expressions. Therefore, it is preferable.
(Formula 1) tX> 1.5 × tX ′
(Formula 2) tY> 1.5 × tY ′

  The thickness ratio in Formula 1 and Formula 2 is more preferably 2 times or more, still more preferably 5 times or more, and particularly preferably 10 times or more. The upper limit is not particularly limited, but is usually 500 times or less, more preferably 300 times or less. When tX and tX ′ satisfy the above (Equation 1), the surface roughness can be more easily flattened. On the other hand, when tY and tY ′ satisfy the above (Equation 2), the surface roughness can be more easily adjusted. . Note that either of the above-described film layers (A) and (B) may be the outermost layer having a small surface roughness, and either may be the outermost layer having a large surface roughness. As the inert particles to be included, the above-mentioned ones can be suitably used. In particular, the inert particles to be included in the outermost layer having a large surface roughness are organic from the viewpoint of suppressing backside transfer in the curing step when making a magnetic recording medium. Particles are preferable, and crosslinked polystyrene organic particles and silicone resin particles are particularly preferable. On the other hand, as the inert particles to be contained in the outermost layer having a small surface roughness, it is preferable to uniformly disperse the inert particles having a uniform particle size with a small particle size without agglomeration. Spherical inert particles are preferred, and true spherical silica particles are particularly preferred.

  By the way, the biaxially oriented multilayer laminated film of the present invention only needs to have a laminated structure in which 11 or more film layers A and B are alternately laminated, and a third film layer different from that is formed. Also good. In particular, when it is necessary to reduce the thickness of the film layer, it is difficult to form a surface that achieves both slipperiness and surface flatness only at the portion where the laminated structure is formed, but such a third layer is provided. Thus, it is possible to more easily form a surface having both slipperiness and surface flatness. In the case of providing the third layer, the outermost layer having a large surface roughness of the biaxially oriented multilayer laminated film contains a third particle containing 0.001 to 5% by weight of inert particles having an average particle size of 0.01 to 1.0 μm. Film layers A and B, which are composed of layers (C layer) and form a laminated structure, contain no inert particles or particles having a smaller average particle size than the film layer forming the outermost layer having the large surface roughness. It is preferable to contain inert particles having the same average particle size or less. In addition, it is preferable that the third layer is different from the above-described film layer A or B in the kind, size, or amount of the inert particles contained in order to have a difference in surface roughness. On the other hand, the composition of the polymer of the third layer is not particularly limited, and may be a known thermoplastic resin other than polyester, but is preferably the same polymer as the above-described film layers A and B. . In addition, when the thickness of the third layer is increased, curling is more easily suppressed. Therefore, the composition of the polymer of the third layer has an intermediate composition between the film layers A and B forming the above-described laminated structure. It is preferable.

  The surface on which the third layer is laminated may be any surface of the film layer (A) or (B). In addition to the above-mentioned combination, the third layer is formed as the outermost layer having a small surface roughness. It is good also as a layer. The inert particles contained in the third layer are preferably organic particles or a combination of organic particles and inorganic particles. The organic particles are preferably crosslinked polystyrene, silicone resin particles, and inorganic particles are preferably spherical silica, titanium oxide, or the like. .

  The biaxially oriented multilayer laminated film of the present invention has a coating layer (hereinafter sometimes referred to as a fourth layer or a D layer) formed on at least one surface in order to improve slipperiness and adhesion. It may be a thing. When it has a coating film layer, surface roughness should just be satisfied in the state which measured the surface of the coating film layer. This coating layer is formed by coating a water-soluble resin on an unstretched or uniaxially stretched film before the completion of stretching during the film-forming process, hot-melt coating on a film after the film-forming is completed, or on a film after the film-forming is completed. It can be obtained by applying and drying a resin dissolved in the above solvent. The surface on which the coating layer is laminated may be any surface of the film layers (A) and (B) and the third layer, and may be not only one surface but also both surfaces. When the surface on which the coating layer is formed is a flat surface with a small surface roughness, the coating layer may contain inert particles having a small particle size with an average particle size of 1 to 40 nm. preferable. The average particle size of the preferred inert particles is 2-30 nm, especially 5-25 nm. On the other hand, when the surface on which the coating film layer is formed is a rough surface having a large surface roughness, the coating film layer preferably contains particles having an average particle diameter of 30 to 100 nm. Preferred inert particles have an average particle size of 35-80 nm, in particular 35-60 nm. The type of particles is preferably spherical organic particles, and examples thereof include crosslinked polystyrene and silicone resin particles. Moreover, when apply | coating to a rough surface, when hard resin, such as methylcellulose, is contained, since blocking when it is set as a roll state can also be suppressed, it is preferable. In addition, in this invention, when it has a coating film layer, the above-mentioned tX and tY mean the film layer located in the outermost layer side respectively located inside a coating film layer.

  As described above, the thickness of the alternately laminated multilayer portions of the biaxially oriented multilayer laminate film of the present invention is preferably changed between the outermost layer and the others, but the change in thickness is to increase only the outermost layer. It is also possible to change the thickness of the alternately laminated portions continuously in the thickness direction.

  In addition, to the average thickness (average thickness of the film layer A: tA (nm), average thickness of the film layer B: tB (nm)) of the film layers other than the outermost layer forming the laminated structure of the biaxially oriented multilayer laminated film Is not particularly limited, but from the relationship between the total number of layers and the total thickness for ensuring stretchability, 0.5 to 1000 nm is preferable, more preferably 1 to 300 nm, still more preferably 2 to 200 nm, and particularly preferably 3 −100 nm.

The preferred embodiment of the biaxially oriented multilayer laminated film of the present invention will be described in further detail.
When the biaxially oriented multilayer laminated film of the present invention is used as a base film such as a magnetic tape, at least one direction in the film surface direction has a high Young's modulus of 6.0 GPa or more so that the base film does not stretch. It is preferable to have. Moreover, the humidity expansion coefficient can be further reduced by increasing the Young's modulus in this way. The upper limit of Young's modulus is not limited, but is usually 18 GPa. Preferred Young's modulus is 4 to 11 GPa in the longitudinal direction of the film, more preferably 5 to 10 GPa, particularly 5.5 to 9 GPa, and 5 to 18 GPa in the width direction of the film, further 6 to 15 GPa, and more preferably 7 to 12 GPa. It is in the range of 8-10 GPa.

  The biaxially oriented multilayer laminated film of the present invention has a humidity expansion coefficient in at least one direction of 0.1 to 9 ppm /% RH, more preferably 1 to 6 ppm /% RH, and particularly 2 to 5 ppm /% RH. From the viewpoint of dimensional stability when a magnetic recording tape is used. In particular, when used as a base film for a magnetic recording tape, it is preferable that the direction in which the humidity expansion coefficient is small is the width direction of the biaxially oriented polyester film because track deviation and the like can be extremely suppressed. In the present invention, the width direction of the film is a direction orthogonal to the film forming direction of the film (also referred to as a longitudinal direction or a longitudinal direction), and is sometimes referred to as a lateral direction.

The biaxially oriented multilayer laminated film of the present invention has a temperature expansion coefficient in the width direction of −10 to +10 ppm / ° C., more preferably −5 to +5 ppm / ° C., particularly −5 to 0 ppm / ° C. This is preferable in terms of dimensional stability when formed into a tape.
The preferred total thickness of the biaxially oriented multilayer laminate film of the present invention is 1-10 μm, further 2-8 μm, particularly preferably 3-7 μm.

<Method for producing aromatic polyester (A) and hydrophobic resin (B)>
The aromatic polyester (A) and the hydrophobic resin (B) used in the present invention can be produced by a method known per se.
In addition, the aromatic polyester (A) and the hydrophobic resin (B) in the present invention include other thermoplastic polymers, stabilizers such as ultraviolet absorbers, antioxidants, plastics, and the like within a range not inhibiting the effects of the present invention. Agents, lubricants, flame retardants, release agents, pigments, nucleating agents, fillers, glass fibers, carbon fibers, layered silicates and the like may be blended as necessary. Examples of other types of thermoplastic polymers include aliphatic polyester resins, polyamide resins, polycarbonates, ABS resins, polymethyl methacrylate, polyamide elastomers, polyester elastomers, polyetherimides, polyimides, and the like.

<Inert particle addition method>
The method for adding the above-described inert particles in the present invention to the film layers (A), (B) and the third layer is not particularly limited, and may be added at the polymerization stage of the resin constituting each layer, What is necessary is just to knead with a twin-screw kneading extruder etc. after superposition | polymerization. Preferably, since it is easier to improve the dispersibility of the particles in the film layer, a master polymer containing a larger amount of inert particles in the polymerization stage than that used in the final film is prepared, and it is made inert. A method of diluting with a polymer containing no particles to a desired particle concentration is preferred. At that time, it is preferable to remove coarse particles by filtration with a filter or the like.

<Film production method>
The biaxially oriented multilayer laminated film of the present invention is obtained by stretching in the film forming direction and the width direction to enhance the molecular orientation in each direction. For example, it can be produced by the following method to improve the film forming property. It is preferable because the Young's modulus can be easily improved while maintaining.

  First, the aromatic polyester (A) and the hydrophobic resin (B) are used as raw materials, and after drying these, the melting state, preferably the melting point (Tm: ° C.) to (Tm + 70) ° C. of the polymer forming each layer. After melting at a temperature, the film is divided by a predetermined number of layers in the flow path, alternately laminated, then discharged from the die, rapidly solidified to form a laminated unstretched film, and the laminated unstretched film is biaxially stretched. At this time, by devising the shape of the branch flow path, it is possible to increase only the thickness of the outermost layer or to gradually change the thickness in the thickness direction. It is also possible to make a structure in which the third resin is merged and laminated on one of the outermost layers after forming the alternately laminated layers and before pushing out from the die.

Biaxial stretching may be sequential biaxial stretching or simultaneous biaxial stretching.
Here, a manufacturing method in which longitudinal stretching, lateral stretching, and heat treatment are performed in this order by sequential biaxial stretching will be described as an example. First, the first longitudinal stretching is performed by stretching 3 to 10 times at a glass transition temperature (Tg: ° C.) to (Tg + 40) ° C., whichever is higher, of the aromatic polyester (A) or the hydrophobic resin (B). Then, the film is stretched 3 to 10 times at a temperature of (Tg + 10) to (Tg + 50) ° C. at a higher temperature than the longitudinal stretching in the transverse direction, and further at a temperature below the melting point of the polymer as a heat treatment and (Tg + 50) to (Tg + 150). It is preferable to perform heat setting treatment at a temperature of 1 ° C. for 1 to 20 seconds, and further for 1 to 15 seconds. In particular, the temperature of the heat setting treatment is preferably 180 to 220 ° C, more preferably 190 to 210 ° C.

  Although the above description has been made on sequential biaxial stretching, the biaxially oriented multilayer laminated film of the present invention can be produced by simultaneous biaxial stretching in which longitudinal stretching and transverse stretching are simultaneously performed, for example, the stretching ratio and stretching temperature described above. You can refer to these.

  Furthermore, it is also possible to provide a coating layer for the purpose of improving slipperiness and easy adhesion. The coating layer can be formed by applying an aqueous coating solution to an unstretched film or a uniaxially stretched film during the film-forming process and drying it while stretching and heat-setting, or by applying it after the biaxial stretching is completed. You can also.

  The thickness of the biaxially oriented multilayer laminated film of the present invention may be appropriately determined according to the use. When used for the base film of a magnetic recording tape, the thickness is preferably 2 to 10 μm, more preferably 3 to 7 μm, and particularly preferably 4 to 6 μm. .

  In addition, about the method of containing particle | grains, a publicly known method can be employ | adopted, for example, in the manufacturing process of aromatic polyester (A) or hydrophobic resin (B), you may add to a reaction system, or aromatic You may add to a polyester (A) and hydrophobic resin (B) by melt-kneading. From the viewpoint of the dispersibility of the particles, the aromatic polyester (A) or the hydrophobic resin (B) having a high particle concentration is preferably added to the reaction system of the aromatic polyester (A) or the hydrophobic resin (B). A method of producing as a polymer and mixing the master polymer with a polyester composition containing no particles or having a low particle concentration is preferred.

  According to the present invention, the biaxially oriented multilayer laminated film of the present invention is used as a base film, and a nonmagnetic layer and a magnetic layer are formed in this order on the surface on the flat surface side, and the backcoat layer is formed on the surface on the running surface side. It can be set as a magnetic recording tape by forming.

<Laminate>
By the way, the biaxially oriented multilayer laminated film of the present invention may be used as a base film of a magnetic recording medium, but a metal is further formed on one surface or both surfaces of the biaxially oriented multilayer laminated film of the present invention. It is good also as a laminated body in which the layer (M layer) which consists of a kind or a metallic inorganic compound was formed, and a dimensional change can be made still smaller by it. Examples of metals include Cu, Zn, Al, Si, Fe, Ag, Ti, Mg, Sn, Zr, In, Cr, Mn, V, Ni, Mo, Ce, Ga, Hf, Nb, Ta, and Y. , W and the like, and examples of the metal-based inorganic compound include those obtained by oxidizing these metals.

  When the M layer is formed on both surfaces, different metal components may be included on both surfaces, and a plurality of types of metal components may be mixed, but more preferably on both surfaces. It is better to contain a kind of metal component. Among these, the metal-based oxide preferably contains at least one of aluminum, copper, zinc, silver, and silicon elements from the viewpoints of controllability of the degree of oxidation, dimensional stability, productivity, and environmental properties, and more preferably. Is preferably composed mainly of an aluminum element.

  In the present invention, the thickness of each M layer is preferably in the range of 15 to 90 nm. When the thickness of the M layer is smaller than 15 nm, the reinforcing effect is small, and the environmental change due to temperature and humidity and the effect of reducing elongation during processing at high temperatures tend to be small. The lower limit of the thickness of the M layer is preferably 20 nm, more preferably 25 nm. On the other hand, when the thickness of the M layer is larger than 90 nm, the bending rigidity tends to increase, and the surface tends to become rough due to crystal grains or the like. The upper limit of the thickness of the M layer is preferably 80 nm, more preferably 70 nm. The thickness of the M layer may be different on both surfaces as long as it is within the above range. It is preferable to control both surfaces to the same thickness because the obtained support tends to be flat. In addition, when the two surfaces are controlled to have different thicknesses, the obtained support may cause cupping. However, if necessary, the magnetic head can be used for a magnetic recording medium. The hit may be good. In that case, the surface (A) on the side where the magnetic layer is provided is convex between the surface (A) on the side where the magnetic layer is provided and the surface on the side where the magnetic layer is not provided, ie, the surface (B) on the backcoat layer side. A cupping shape is preferred. In order to realize such a cupping shape, when the thickness of the M layer on the A plane side and the thickness of the M layer on the B plane side are Ma and Mb, respectively, the thickness ratio (Ma / Mb) is 1 to 5 It is preferable that Ma / Mb is more preferably 1 to 3, and further preferably 1 to 2.

  By the way, in the laminate of the present invention, the product of the Young's modulus (GPa) in the longitudinal direction of the laminate and the thickness (μm) of the support is preferably 30 or more. If this product is less than 30, for example, when a magnetic tape is used, it extends in the longitudinal direction due to the tension in the coating process and tends to wrinkle in the width direction, or when used as a magnetic tape, the tension applied in the running direction of the magnetic tape. This is because it extends in the longitudinal direction (longitudinal direction) and contracts in the width direction, which easily causes track misalignment. Of course, in order to increase this product, the Young's modulus (GPa) in the longitudinal direction of the support and the thickness (μm) of the support should be increased, but as described above, it is supported from the viewpoint of storage capacity. The thinner the body, the better. In that respect, since the biaxially oriented multilayer laminate film has very dimensional stability, the laminate of the present invention has an extremely low thickness of 4.5 μm or less, and further 4 μm or less while making the M layer thinner. Even if it is very thin, application suitability can be maintained at a high level.

  The laminate of the present invention has excellent dimensional stability, particularly when used as a base film such as a magnetic tape, and the temperature expansion coefficient (αt) in the width direction of the laminate is −10 to −10 from the viewpoint of suppressing track misalignment. It is preferably 10 ppm / ° C. or less. The temperature expansion coefficient (αt) in the width direction of the preferred laminate is in the range of −7 to 5 ppm / ° C., more preferably −5 to 0 ppm / ° C. Such a temperature expansion coefficient (αt) can be adjusted by αt of the biaxially oriented multilayer laminated film, the material and thickness of the M layer, and the like. In addition, the laminate of the present invention has excellent dimensional stability, in particular, a humidity expansion coefficient (αh) in the width direction of the film of 0 when used as a base film such as a magnetic tape, from the viewpoint of suppressing track shift and the like. It is preferable to be in the range of ˜5 ppm /% RH, more preferably 1 to 4.5 ppm /% RH. Such a humidity expansion coefficient (αh) can be adjusted by αh of the biaxially oriented multilayer laminated film, the material and thickness of the M layer, and the like.

  In the laminate of the present invention, the sum of the Young's modulus in the longitudinal direction and the width direction of the support is 10 to 22 GPa, and the ratio Em / Et between the Young's modulus Em in the longitudinal direction and the Young's modulus Et in the width direction is It is preferable that it is in the range of 0.5 to 1.0 because the manufacturing process can be easily stabilized while having the above dimensional stability.

<Method for producing support>
First, a method for forming the M layer on the biaxially oriented multilayer laminated film obtained as described above will be described by taking as an example a method for forming the M layer on both sides using a vacuum deposition apparatus.
First, in a vacuum deposition apparatus, a biaxially oriented multilayer laminated film travels from an unwinding roll part to a winding roll part through a cooling drum inside a vacuum chamber. At that time, a metal material is put in a crucible and heated and evaporated by applying an electron beam irradiated from an electron gun to the crucible, and deposited on a biaxially oriented multilayer laminated film on a cooling drum. At this time, if oxygen gas is introduced from the oxygen supply nozzle, the evaporated metal can be deposited while undergoing an oxidation reaction. Also, after vapor deposition on one surface (first side), remove the one-side vapor deposition from the winding roll part, set it on the unwinding roll part, and vapor deposition on the opposite side surface (second side) in the same way Can be formed on both sides.

Here, the inside of the vacuum chamber 12 is preferably decompressed to 1.0 × 10 ^{−8 to} 1.0 × 10 ² Pa. Further, in order to form a dense M layer with few deteriorated portions, it is preferable to reduce the pressure to 1.0 × 10 ^{−6 to} 1.0 × 10 ⁻¹ Pa. The cooling drum preferably has a surface temperature in the range of −40 to 60 ° C. More preferably, it is -30-30 degreeC, More preferably, it is -30-30 degreeC. When an electron beam is used, it is preferable that the output is within a range of 2.0 to 8.0 kW. More preferably, it is 3.0-7.0 kW, More preferably, it exists in the range of 4.0-6.0 kW. Note that the metal material may be evaporated by heating the crucible directly.

  The oxygen gas is preferably introduced into the vacuum chamber at a flow rate of 0.5 to 10 L / min using a gas flow rate control device. More preferably, it is 1.5-8 L / min, More preferably, it is 2.0-5 L / min.

  The conveying speed of the biaxially oriented multilayer laminated film inside the vacuum chamber is preferably 20 to 200 m / min. More preferably, it is 30-100 m / min, More preferably, it is 40-80 m / min. When the conveyance speed is slower than 20 m / min, it is necessary to considerably reduce the evaporation amount of the metal in order to control the M layer thickness as described above. Control of thickness and oxidation degree becomes very difficult. When the conveyance speed is higher than 200 m / min, the contact time with the cooling drum is shortened, so that tears and wrinkles are generated due to heat, and productivity tends to be reduced. In addition, the metal vapor and the oxygen gas are likely to be formed in an insufficient reaction state, and the degree of oxidation may be difficult to control. Vapor deposition may be performed one side at a time, or both sides may be performed in one step.

  In order to stabilize the M layer and improve the denseness after the deposition, it is preferable to return the inside of the vacuum deposition apparatus to normal pressure and to rewind the wound film. In particular, in order to reduce the number of unbonded atoms, it is preferable to perform humidification rewinding because the chance of contact between the water vapor and the M layer is increased. The humidification rewinding is preferably performed at 20 to 40 ° C. and 60 to 80% RH. Further, aging is preferably performed at a temperature of 20 to 50 ° C. for 1 to 3 days, and more preferably, aging is performed in an environment where the humidity is 60% or more and no condensation occurs.

  Next, a method for manufacturing a magnetic recording medium will be described. When the laminated body obtained as described above is used as a support for a magnetic recording medium, for example, it is slit to a width of 0.1 to 3 m and conveyed at a speed of 20 to 300 m / min and a tension of 50 to 300 N / m. On one surface (A), a magnetic coating material and a non-magnetic coating material are applied in multiple layers using an extrusion coater. A magnetic paint is applied to the upper layer with a thickness of 0.1 to 0.3 μm, and a nonmagnetic paint is applied to the lower layer with a thickness of 0.5 to 1.5 μm. Thereafter, the support coated with the magnetic coating material and the nonmagnetic coating material is magnetically oriented and dried at a temperature of 80 to 130 ° C. Next, a back coat is applied to the opposite surface (B) with a thickness of 0.3 to 0.8 μm, calendered, and then wound up. The calendering is performed using a small test calender (steel / nylon roll, 5 stages) at a temperature of 70 to 120 ° C. and a linear pressure of 0.5 to 5 kN / cm. Thereafter, the film is aged at 60 to 80 ° C. for 24 to 72 hours, slit to a width of 1/2 inch (1.27 cm), and a pancake is produced. Next, a specific length from this pancake is incorporated into a cassette to obtain a cassette tape type magnetic recording medium.

  Here, examples of the composition of the magnetic paint include the composition in the measurement of Examples described later. In addition to the above, the magnetic recording medium may have a ferromagnetic thin film type magnetic layer provided with cobalt, nickel, iron or the like by vapor deposition or sputtering.

  The magnetic recording medium thus obtained can be used, for example, for data recording, specifically for computer data backup (for example, linear tape recording media (LTO4, LTO5, etc.)) and digital image recording such as video. It can use suitably for a use etc.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the present invention, the characteristics were measured and evaluated by the following methods.

(1) Intrinsic viscosity The intrinsic viscosity of the obtained polyester was determined by dissolving the polymer using o-chlorophenol and measuring it at 35 ° C.

(2) Glass transition point and melting point Glass transition point and melting point are prepared by preparing aromatic polyester (A) and hydrophobic resin (B) used for each layer, DSC (trade name: Thermal, manufactured by TA Instruments Co., Ltd.). lyst 2920) at a temperature rising rate of 20 ° C./min.

(3) Young's modulus The obtained biaxially oriented multilayer laminated film and laminate are cut out with a sample width of 10 mm and a length of 15 cm, and a universal tensile testing device under the conditions of 100 mm between chucks, a tensile speed of 10 mm / min, and a chart speed of 500 mm / min. Pull with Toyo Baldwin (trade name: Tensilon). The Young's modulus was calculated from the tangent of the rising portion of the obtained load-elongation curve.

(4) Humidity expansion coefficient (αh, CHE)
The obtained biaxially oriented multilayer laminated film and laminate were cut into a length of 15 mm and a width of 5 mm so that the film forming direction or the width direction of the film was the measuring direction, set in TMA3000 manufactured by Vacuum Riko, and nitrogen at 30 ° C. Under the atmosphere, the length of each sample at a humidity of 30% RH and a humidity of 70% RH is measured, and a humidity expansion coefficient is calculated by the following equation. In addition, the measurement direction is the longitudinal direction of the cut out sample, the measurement was performed 5 times, and the average value was αh.
αh = (L ₇₀ −L ₃₀ ) / (L ₃₀ × ΔH)
Here, L ₃₀ in the above formula is a sample length (mm) when 30% RH, L ₇₀ is a sample length (mm) when 70% RH, ΔH: 40 (= 70-30)% RH is there.

(5) Temperature expansion coefficient (αt, CTE)
The obtained biaxially oriented multilayer laminated film and laminate were cut into a length of 15 mm and a width of 5 mm, respectively, so that the film forming direction or the width direction of the film was the measurement direction, and set in TMA3000 manufactured by Vacuum Riko, under a nitrogen atmosphere. (0% RH), pre-treatment at 60 ° C. for 30 minutes, and then cooled to room temperature. Thereafter, the temperature is raised from 25 ° C. to 70 ° C. at 2 ° C./min, the sample length at each temperature is measured, and the temperature expansion coefficient (αt) is calculated from the following equation. In addition, the measurement direction is the longitudinal direction of the sample cut out, the measurement was performed 5 times, and the average value was used.
αt = {(L ₆₀ −L ₄₀ )} / (L ₄₀ × ΔT)} + 0.5
Here, L ₄₀ in the above formula is the sample length (mm) at 40 ° C., L ₆₀ is the sample length (mm) at 60 ° C., ΔT is 20 (= 60-40) ° C., 0.5 Is the temperature expansion coefficient (ppm / ° C.) of quartz glass.

(6) Thickness of biaxially oriented multilayer laminated film, laminated body, each film layer and M layer 10 layers of the obtained biaxially oriented multilayer laminated film or laminated body are removed while excluding air between layers. In accordance with the above, the thickness is measured by a 10-sheet overlapping method using a dial gauge MDC-25S manufactured by Mitutoyo Corporation, and the thicknesses of the biaxially oriented multilayer laminated film and the laminated body per sheet are calculated. This measurement was repeated 10 times, and the average value was taken as the total thickness of the biaxially oriented multilayer laminate film and laminate per sheet.
On the other hand, the thicknesses of the M layer, the film layer (A), and the film layer (B) are obtained by fixing a small piece of the film with an epoxy resin, and using an ultrathin section having a thickness of about 60 nm with a microtome (the film forming direction and Cut in parallel to the thickness direction). The sample of this ultra-thin section was observed with a transmission electron microscope (H-800 type manufactured by Hitachi, Ltd.), and the thickness of the M layer, the film layer (A), the film layer (B), and the film layer (C) from the boundary. Asked.

(7) Winding property 100 biaxially oriented multilayer laminated film rolls that have been formed into a film are cut into 100 pieces in a width of 1 m and a length of 10000 m. Expressed as a number.
◎ No drawbacks.
○ There are slight wrinkles or dents.
△ There are noticeable wrinkles or dents or bumps.
× There are two or more of wrinkles and dents.

(8) Surface roughness (Ra)
Measured using a non-contact type three-dimensional surface roughness meter (manufactured by ZYGO: New View 5022) at a measurement magnification of 25 times and a measurement area of 283 μm × 213 μm (= 0.0603 mm ² ), and incorporated in the roughness meter The center surface average roughness (Ra) was determined by the surface analysis software Metro Pro. In addition, the surface was measured when there existed the 3rd layer and the 4th layer.

(9) Creation of data storage (magnetic tape)
A non-magnetic paint or magnetic paint having the following composition is applied to the surface of the biaxially oriented multi-layer laminated film having a length of 850 m, which is slit to a width of 500 mm under a tension condition of 20 MPa, or the surface roughness of the laminated body is smaller. At the same time, the non-magnetic layer and the magnetic layer after drying are applied by changing the film thickness so that the thicknesses are 1.2 μm and 0.1 μm, respectively, magnetically oriented, and dried at 120 ° C. for 30 seconds. Further, after calendering with a small test calender (steel roll / nylon roll, 5 stages) at a temperature of 70 ° C. and a linear pressure of 200 kg / cm, curing is performed at 70 ° C. for 48 hours.
Composition of non-magnetic coating material: Titanium dioxide fine particles: 100 parts by weight Esrec A (Sekisui Chemical vinyl chloride / vinyl acetate copolymer: 10 parts by weight Nipporan 2304 (Japan polyurethane polyurethane elastomer): 10 parts by weight Coronate L ( Polyisocyanate made of Japanese polyurethane): 5 parts by weight, lecithin: 1 part by weight, methyl ethyl ketone: 75 parts by weight, methyl isobutyl ketone: 75 parts by weight, toluene: 75 parts by weight, carbon black: 2 parts by weight, lauric acid: 1.5 Composition of parts by weight of magnetic paint Iron (length: 0.3 μm, needle ratio: 10/1, 1800 oersted)
: 100 parts by weight-ESREC A (Sekisui Chemical's vinyl chloride / vinyl acetate copolymer: 10 parts by weight-Nipponran 2304 (polyurethane elastomer made by Nippon Polyurethane): 10 parts by weight-Coronate L (polyisocyanate made by Nippon Polyurethane): 5 parts by weight Parts, lecithin: 1 part by weight, methyl ethyl ketone: 75 parts by weight, methyl isobutyl ketone: 75 parts by weight, toluene: 75 parts by weight, carbon black: 2 parts by weight, lauric acid: 1.5 parts by weight A layered film is prepared, and a back coat having the following composition is applied to the opposite surface of the magnetic layer so that the thickness of the solid content is 0.5 μm, and then a small test calender device (steel / nylon roll, 5 stages). And calendering and winding at a temperature of 85 ° C. and a linear pressure of 200 kg / cm. Was inserted into a case for LTO, and a data storage cartridge having a length of 850 m and a magnetic recording capacity of 0.8 TB was produced.
(Backcoat composition)
Carbon black (average particle size 20 nm): 95 parts by weight
Carbon black (average particle size 280 nm): 10 parts by weight
・ Α alumina: 0.1 parts by weight
・ Modified polyurethane: 20 parts by weight
-Modified vinyl chloride copolymer: 30 parts by weight
・ Cyclohexanone: 200 parts by weight
・ Methyl ethyl ketone: 300 parts by weight
・ Toluene: 100 parts by weight

(10) Electromagnetic conversion characteristics Using a commercially available LTO-G3 drive (manufactured by IBM Corporation, equipped with an MR reproducing head), the magnetic tape produced by the method of (9) above is subjected to BBSNR (average signal intensity and broadband integrated average noise). Ratio). The results were evaluated based on the results of Example 1.

(11) Water absorption rate An unstretched film having a thickness of 100 μm was prepared from the resin used for each layer, and measured according to the JIS K7209A method.

(12) Thickness of M layer
Cross-sectional observation is performed under the following conditions, and the average value of the obtained thicknesses (nm) of a total of nine points is calculated to obtain the thickness (nm) of the M layer.
Measurement device: Transmission electron microscope (TEM) Hitachi H-7100FA type
・ Measurement conditions: Acceleration voltage 100kV
・ Measurement magnification: 200,000 times
・ Sample preparation: Ultra-thin film section method
-Observation surface: TD-ZD cross section
-Number of measurements: 3 points per field of view and 3 fields of view are measured.

[Example 1]
Polyethylene terephthalate and ethylene glycol are subjected to an esterification reaction and a transesterification reaction in the presence of titanium tetrabutoxide, followed by a polycondensation reaction, and 1.5 mol% of a glycol component is a polyethylene-diethylene glycol component. A terephthalate pellet was obtained. The intrinsic viscosity of the obtained polyethylene terephthalate was 0.65. Polyetherimide was mixed with the obtained pellets so as to have a concentration of 10%, kneaded by the same rotating twin screw extruder, and then pelletized again to obtain a polymer for layer A (A-1).
In addition, using synergistic polystyrene resin, ZAREC 130ZC manufactured by Idemitsu Petrochemical Co., Ltd., using cross-linked polystyrene particles having an average particle size of 0.25 μm using a co-rotating twin-screw kneader so that the concentration in the pellet is 0.1% by weight. The hydrophobic resin (B-1) for film layer (B) was added.

(A-1) and (B-1) thus obtained were dried at 170 ° C. for 3 hours and then supplied to an extruder, heated to 295 ° C. to a molten state, and (A-1) After the 101 layer and (B-1) were branched into 100 layers, the layers (A-1) and (B-1) were laminated by a multilayer feedblock device so that the layers were alternately laminated. In addition, the partial 1 layer which is the outermost layer of (A-1) was branched into multiple layers before branching, and was laminated after alternating lamination of the A-1 layer 100 layer and the B-1 layer 100 layer. Next, it is led to a die while maintaining the laminated state, and is extruded in a sheet shape onto a cooling drum having a rotating temperature of 20 ° C. in a molten state, and the layers (A-1) and (B-1) are formed. A total of 201 unstretched multilayer laminated films laminated alternately were prepared. The discharge ratio of the B layer and the A layer was 3: 2. The obtained unstretched laminated film is heated between two sets of rollers having different rotation speeds along the film forming direction from above with an IR heater so that the film surface temperature becomes 105 ° C. Direction) was performed at a draw ratio of 4.4 times to obtain a uniaxially stretched film. Then, this uniaxially stretched film is led to a stenter, stretched in the transverse direction (width direction) at 125 ° C. at a stretching ratio of 3.9 times, and then heat-set at 200 ° C. for 5 seconds to form a biaxially oriented film having a thickness of 5 μm. A multilayer laminated film was obtained.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Example 2]
Dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol are esterified and transesterified in the presence of titanium tetrabutoxide, followed by a polycondensation reaction, and 1.5 mol% of the glycol component is diethylene glycol. Polyethylene-2,6-naphthalate (A-2) for film layer (A) as a component was obtained. The intrinsic viscosity of the obtained polyethylene-2,6-naphthalate was 0.63. Polyethylene-2,6-naphthalate (A-2) contains 0.1% by weight of silica particles having an average particle diameter of 0.1 μm based on the weight of the resin composition obtained before the polycondensation reaction. It was. As the resin for the B layer, (B-1) used in Example 1 was used.

The aromatic polyesters (A-2) and (B-1) thus obtained were dried at 170 ° C. for 6 hours, then supplied to an extruder, heated to 295 ° C. to be in a molten state, (A-2 ) For the outermost layer (AX layer), and then the remaining (A-2) is branched into 50 layers, and the hydrophobic resin of (B-1) is branched into 50 layers. After the layers (A-2) and (B-1) were stacked using a multilayer feed block device in which layers were alternately stacked, the outermost AX layer was stacked. While maintaining this laminated state, it is led to a die, extruded in a sheet form onto a cooling drum having a rotating temperature of 50 ° C. in a molten state, and the layers (A-2) and (B-1) are alternately laminated. A total of 101 unstretched multilayer laminated films were produced. The ejection ratio of the B layer and the A layer was 3: 1.2. It was. Then, between two sets of rollers having different rotational speeds along the film forming direction, the film surface temperature is heated from above by an IR heater so that the film surface temperature becomes 135 ° C., and stretching in the machine direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 5.1 times. Then, this uniaxially stretched film is guided to a stenter, stretched in the transverse direction (width direction) at 145 ° C. at a stretching ratio of 6.7 times, and then subjected to heat setting treatment at 215 ° C. for 5 seconds to obtain a thickness of 4.2 μm. An axially oriented multilayer laminated film was obtained.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Example 3]
As the polyester for layer A (A-3), Idemitsu Petrochemical ZAREC142AE copolymerized with α-methylstyrene was prepared as polyethylene terephthalate containing no inert particles and the resin for layer B (B-3). Moreover, what added 0.1 weight% of crosslinked polystyrene particles with an average particle diameter of 0.25 micrometer to polyethylene terephthalate as C layer polyester (C-3) was prepared. These were dried at 170 ° C. for 4 hours and then supplied to three extruders, respectively. A-3 and B-3 were branched into 11 layers and 10 layers, respectively, and then alternately laminated, and then a C layer was laminated on one side. A biaxially oriented multilayer laminate film was obtained in the same manner as in Example 1 except that the draw ratio was 3.0 times in the longitudinal direction and 5.0 times in the width direction.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Example 4]
Resin B-4 was prepared by using PPS (Fortron 0220A9 manufactured by Polyplastics Co., Ltd.) as the resin for the B layer, and adding 0.2% by weight of true spherical silica having an average particle size of 0.3 μm to the resin. The polyester of A-2 and the resin of B-4 were dried at 170 ° C. for 6 hours and then melted using two extruders. Before the alternate lamination, the A-2 resin and B-4 resin for the outermost layer are once branched, and further, the A-2 resin is alternately laminated to 24 layers and the B-4 resin is alternately laminated to 24 layers. -2 resin and B-4 resin were laminated. Thereafter, a uniaxially stretched film was obtained in the same manner as in Example 2 except that the longitudinal stretching ratio was 4.8 times. A coating liquid having the following composition was applied to the outermost layer of A-2 on the obtained film, then continuously introduced into the tenter, stretched 6.8 times in the width direction, and 4 at 220 ° C. A biaxially oriented multilayer laminated film was obtained by heat setting for 2 seconds.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Example 5]
For the A layer, A-5 in which the additive particles of the A-1 resin were changed to crosslinked polystyrene particles having an average particle size of 0.06 μm was prepared, and for the B layer, the same B-4 as in Example 4 was used. Each was dried at 170 ° C. for 4 hours and then supplied from two extruders. A-5 had a final thickness of 100-5 nm and B-4 had a final thickness of 20-70 nm. The distribution was continuously changed to branch into 41 layers, which were alternately stacked. In addition, in lamination | stacking, it laminated | stacked so that the thickest layer of A layer and B layer might become both outermost layers, respectively, and the unstretched sheet was obtained similarly to Example 1. FIG. A biaxially oriented multilayer laminated film was obtained in the same manner as in Example 1 except that the obtained unstretched sheet was stretched 3.0 times in the longitudinal direction and 6.5 times in the width direction.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Example 6]
The 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component as polyester for layer A is copolymerized with PEN at 24 mol%, and 0.1 g both of spherical silica having an average particle size of 0.1 μm is obtained. Added A-6 was prepared. For layer B, B-6 prepared by adding 0.1% by weight of crosslinked polystyrene particles having an average particle size of 0.25 μm to a cycloolefin copolymer (manufactured by Polyplastics, trade name: TOPAS 6017, glass transition temperature 178 ° C.) is prepared. did. A-6 and B-6 were each dried at 170 ° C. for 6 hours, and then operated in the same manner as in Example 2 except that the draw ratio was 5.3 times in the longitudinal direction and 7.7 times in the width direction. Thus, a biaxially oriented multilayer laminated film was obtained.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Comparative Example 1]
In Example 1, the resin for the B layer was not SPS, but 10% by weight of polyetherimide was used, and the draw ratio was changed to 4.2 times in the longitudinal direction and 3.8 times in the width direction. In the same manner as above, a biaxially oriented multilayer laminated film was obtained.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Comparative Example 2]
In Example 2, a biaxially oriented multilayer laminated film was obtained in the same manner as in Example 2 except that the particles added to the film B layer and the amount added were as shown in Table 1.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Comparative Example 3]
A biaxially oriented multilayer laminated film was obtained in the same manner as in Example 4 except that the outermost layer of the A layer was not formed.
The properties of the obtained biaxially oriented multilayer laminated film are shown in Table 1.

[Comparative Example 4]
In Example 2, the same operation as in Example 1 was repeated except that it was changed to a two-layer laminated film of one A layer and one B layer instead of multilayer lamination. In this case, curling and delamination of the film occurred, the clip could not be gripped in the transverse stretching process, and a biaxially oriented film could not be obtained.

  In Table 1, PET is polyethylene terephthalate, PEN is polyethylene 2,6-naphthalate, PEI is polyetherimide, SPS is syndiotactic polystyrene, PPS is polyethersulfone, and COP is cyclohexane. The olefin polymer, ANA is 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component, PES is polyester, PS is crosslinked polystyrene particle, silica is silica particle, CTE is temperature expansion coefficient (αt), CHE means the humidity expansion coefficient (αt).

[Example 7]
M layers were provided on both sides of the biaxially oriented multilayer laminate film produced in Example 5 by the following method. First, the obtained biaxially oriented multilayer laminated film was set in a film traveling device installed in a vacuum deposition apparatus, and after a high vacuum of 1.00 × 10 ⁻³ Pa was applied, a cooling metal drum at 20 ° C. Ran through. At this time, the aluminum target was heated and evaporated with an electron beam, oxygen was introduced, and an M layer (thickness: 60 nm) of partially oxidized aluminum having a molar ratio of aluminum to oxygen of 42:58 was formed. In the same manner, an M layer was formed on the opposite surface to prepare a laminate.
The obtained laminate has a temperature expansion coefficient in the width direction of −1.9 ppm / ° C., a humidity expansion coefficient in the width direction of 1.6 ppm /% RH, a Young's modulus of 6.6 GPa in the film forming direction, and 10.5 GPa in the width direction. Ra on the surface on the RaX side was 3.5 nm, and Ra on the surface on the RaY side was 6.0 nm.

[Example 8]
Example 7 is the same as Example 7 except that silica (SiO) is used instead of aluminum, the silicon oxide is a partial silicon oxide having a molar ratio of 37:63, and the thickness is changed to 80 nm. In the same manner, an M layer was formed to produce a laminate.
The obtained laminate has a temperature expansion coefficient in the width direction of 2.6 ppm / ° C., a humidity expansion coefficient in the width direction of 1.7 ppm /% RH, a Young's modulus of 6.1 GPa in the film forming direction, 10.0 GPa in the width direction, Ra on the RaX side surface was 3.5 nm, and Ra on the RaY side surface was 6.0 nm.

[Example 9]
In Example 7, except that oxygen was not introduced, the M layer was formed in the same manner as in Example 7 to prepare a laminate.
The obtained laminate has a temperature expansion coefficient in the width direction of 4.4 ppm / ° C., a humidity expansion coefficient in the width direction of 1.6 ppm /% RH, a Young's modulus of 5.9 GPa in the film forming direction, and 9.8 GPa in the width direction. Ra on the RaX side surface was 3.5 nm, and Ra on the RaY side surface was 6.0 nm.

  Since the biaxially oriented multilayer laminated film and laminate of the present invention have excellent dimensional stability and surface flatness, they can be used in various applications and are particularly suitable as a support for high-density magnetic recording media. Available.

Claims (13)

Biaxially oriented multilayer laminate having a laminated structure in which film layers A made of aromatic polyester (A) and film layers B made of hydrophobic resin (B) having a water absorption of 0.1% or less are alternately laminated. Film having one surface roughness (RaX) in the range of 0.5-5 nm, the other surface roughness (RaY) being 1 nm or more larger than RaX and 10 nm or less, and film layer A or B Any one of the film layers forms both of the two outermost layers, and the film layer on the side not forming the outermost layer contains 0.001 to 5% by weight of inert particles having an average particle size of 0.01 to 1.0 μm. The film layer on the side forming the outermost layer does not contain inert particles, or contains particles having a smaller average particle size than the film layer on the side not forming the outermost layer, or is inert with the same average particle size Less content of particles The thickness (tX) of the film layer that contains and further forms the outermost layer with a small surface roughness is 1.5 times the thickness of the film layer (tY) that forms the outermost layer with a large surface roughness. A biaxially oriented multilayer laminated film characterized by the above. Biaxially oriented multilayer laminate having a laminated structure in which film layers A made of aromatic polyester (A) and film layers B made of hydrophobic resin (B) having a water absorption of 0.1% or less are alternately laminated. Film having one surface roughness (RaX) in the range of 0.5-5 nm, the other surface roughness (RaY) being 1 nm or more larger than RaX and 10 nm or less, and film layer A or B Any one of the above film layers forms the outermost layer having a large surface roughness, and contains 0.001 to 5% by weight of inert particles having an average particle size of 0.01 to 1.0 μm, and has the largest surface roughness. The film layer on the side that does not form the surface layer forms the outermost layer with a small surface roughness and does not contain inert particles, or the average particle size of the film layer on the side that forms the outermost layer with a large surface roughness Contain small particles or Biaxially oriented multi-layer laminated film characterized in that it contains inert particles having an average particle diameter with less content than B. The thickness of the outermost layer having a small surface roughness (tX (nm)), the thickness of the outermost layer having a large surface roughness (tY (nm)), and the thickness of the film layer adjacent to the outermost layer having a small surface roughness (tX ′ ( nm)) thickness of the surface roughness of the film layer adjacent to the large outermost layer (tY '(nm)) is biaxially oriented multilayer laminate film according to claim 2, wherein satisfies at least any one of the following relationship.
(Formula 1) tX> 1.5 × tX ′
(Formula 2) tY> 1.5 × tY ′ Biaxially oriented multilayer laminate having a laminated structure in which film layers A made of aromatic polyester (A) and film layers B made of hydrophobic resin (B) having a water absorption of 0.1% or less are alternately laminated. Biaxially oriented multilayer laminate , wherein one surface roughness (RaX) is in the range of 0.5-5 nm and the other surface roughness (RaY) is 1 nm or more and 10 nm or less than RaX. The outermost layer having a large surface roughness of the film is composed of a third layer (C layer) containing 0.001 to 5% by weight of inert particles having an average particle size of 0.01 to 1.0 μm to form a laminated structure. The film layers A and B do not contain inert particles, contain particles having a smaller average particle size than the film layer forming the outermost layer having a large surface roughness, or contain inert particles having the same average particle size. containing a smaller amount, it Biaxially oriented multi-layer laminated film characterized. 5. The biaxially oriented multilayer according to claim 1 , wherein at least one outermost layer of the biaxially oriented multilayer laminated film is a coating layer (fourth layer, D layer) having inert particles. Laminated film. The biaxially oriented multilayer laminated film according to claim 4 or 5, wherein the film layer A and the film layer B do not contain inert particles. The biaxially oriented multilayer according to any one of claims 1 to 6 , wherein the hydrophobic resin (B) is at least one selected from the group consisting of a styrene polymer having a syndiotactic structure, polyphenylene sulfide, and cycloolefin. Laminated film. The biaxially oriented multilayer laminated film according to any one of claims 1 to 7 , wherein the Young's modulus in the film forming direction and the width direction of the film is 4.5 GPa or more, respectively. The biaxially oriented multilayer laminated film according to any one of claims 1 to 8 , which has a humidity expansion coefficient in the width direction of the film of 0.1 x ^{10-6 to} 9 x ^10-6 / % RH. The biaxially oriented multilayer laminated film according to any one of claims 1 to 9 , wherein the film has a temperature expansion coefficient in the width direction of -10 x 10 ^-6 to 10 x 10 ^-6 / ° C. The biaxially oriented multilayer laminated film according to any one of claims 1 to 10 , wherein the thickness of the film is in the range of 1 to 10 µm. The biaxially oriented multilayer laminated film according to any one of claims 1 to 11 , wherein the biaxially oriented multilayer laminated film is used as a base film of a magnetic recording medium. At least one side, metals or metallic made of an inorganic compound layer (M layer) laminate is provided a biaxially oriented multilayer laminate film according to any one of claims 1 to 11.