JPH09314766A - Multilayer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a product film undergoing a less entrapment of foreign matters or trace of discharge by reducing charges generated at the time of separating the product film from a multilayer film. SOLUTION: The multilayer film is such that at least one layer of a polymer layer (A) consisting of thermoplastic resin (A) and at least one layer of a polymer layer (B) consisting of substantially incompatible thermoplastic resin (B) are adjacent with each other, an interlayer adhesive force between the adjacent two layers is in the range of 0.1-20g/cm, and at least one layer of the polymer layer (B) exists at the outermost layer, wherein the thermoplastic resin (A) is a polyolefin polymer of 3mol.% or lower in a rate of its copolymeric component and the number of discharge traces of the polymer layer (B) existing in the outermost layer obtained by separating from to multilayer film is 5pieces/m<2> or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer film comprising mutually incompatible polymer layers obtained by a coextrusion method, a laminating method or the like, and more specifically, in obtaining a thermoplastic resin film by peeling separation from the multilayer film. In addition, the present invention relates to a multilayer film capable of obtaining a thermoplastic resin film having less discharge marks caused by discharge during peeling and less obstacles due to electrification such as adhered foreign matter caused by charging during peeling.

[0002]

2. Description of the Related Art Systems using bar codes have become widespread in the fields of physical distribution, factory process control, etc., and the demand for ribbons for thermal transfer printers has increased. Also,
Also in the field of magnetic recording, demand for QIC (quarter inch data cartridge) tapes and the like is increasing. As a method for producing films used in these applications with good productivity and economically, coextruding polymers that are incompatible with each other, the resulting unstretched film is at least uniaxially stretched to obtain a multilayer film. From this multilayer film A method of peeling a monolayer film to form two or more products at once (JP-A-51-30862 and JP-A-56-1134).
27, Japanese Patent Laid-Open No. 58-5226).

However, in the above method, the film is charged when the monolayer film is peeled from the multilayer film,
Due to this charging, there are drawbacks such that foreign matter adheres to the film in the peeling step, slitting step, winding step, or the like, and when the charge level becomes large, discharge occurs and discharge marks are generated. These foreign matter and discharge marks are, for example, when ink or magnetic paint is applied to a film, a problem of repelling ink or magnetic paint, a problem of reduction in yield due to pimples on the roll surface due to foreign matter, and a dropout due to uneven coating of magnetic paint. Cause problems, etc.

As a method of preventing such electrification, a method of installing a neutralization bar at the peeling portion to remove and neutralize the electric charge can be considered. However, although this method can reduce the charge level to some extent, it does not provide the effect of eliminating discharge marks.

A method of adding an antistatic agent to each layer constituting the multilayer film is also conceivable, but the bleed type antistatic agent does not exert its effect on the multilayer film.
Further, another problem such as surface contamination due to bleed-out of the antistatic agent occurs.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks, reduce the charge generated when peeling a monolayer film from a multi-layer film, and reduce the inclusion of foreign matter and discharge marks. It is to provide a multilayer film that can be obtained.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
According to the present invention, at least one polymer layer (A) made of a thermoplastic resin (A) and a polymer layer made of a thermoplastic resin (B) substantially incompatible with the thermoplastic resin (A). (B) is adjacent to at least one layer, and the interlayer adhesion between the two adjacent layers is in the range of 0.1 to 20 g / cm, and at least one layer of the polymer layer (B) is the outermost layer. In the existing multilayer film, the thermoplastic resin (A) is a polyolefin polymer having a copolymerization component ratio of 3 mol% or less, and a polymer layer existing in the outermost layer obtained by peeling from the multilayer film ( The number of discharge marks in B) is 5
It is achieved by a multi-layer film having a number of pieces / m ² or less. Hereinafter, the present invention will be described in detail.

[Thermoplastic Resin (A)] In the present invention,
Thermoplastic resin (A) which is a constituent component of the polymer layer (A)
Is a polyolefin polymer having a copolymerization component ratio of 3 mol% or less. This polyolefin polymer is a polymer obtained by polymerizing an olefin compound, and it is necessary that the homopolymer or the copolymer component is 3 mol% or less. Examples of such polyolefin polymers include low density polyethylene, high density polyethylene,
Examples thereof include polypropylene, polybutene, polypentene (polymethylpentene and the like), polybutadiene homopolymers and copolymers thereof.

The copolymerization component of the polyolefin polymer is 3 m
If it exceeds ol%, the polymer layer (B) is changed from the multilayer film.
At the time of peeling and separating, the peeled polymer layer (B) film has a high electrification potential, and when it is wound into a roll, foreign matter is caught and pimples are generated on the roll surface, or the polymer layer (A) The difference in charge potential between the polymer layer (B) and the polymer layer (B) becomes large, and discharge occurs between the two layers, and that portion becomes an electret, resulting in defects such as discharge marks. These defects cause problems such as repelling these paints in the process of applying ink paint or magnetic paint to the film.

It is preferable that the polyolefin polymer is a polyolefin (particularly polypropylene) having a copolymerization component of 1 mol% or less, and a homopolymer (particularly polypropylene homopolymer) because the above defects are less likely to occur. .

However, a part of the acid component may be graft-polymerized in the polyolefin polymer, and the graft-polymerization component may be a carboxylic acid component such as maleic acid.

The thermoplastic resin (A) in the present invention includes
In order to ensure sufficient adhesion between the multilayer film and the casting drum when melt-forming the multilayer film, a quaternary phosphonium salt of sulfonic acid is used as an additive, for example, 0.1.
It is preferable to add 001 to 1% by weight.

Further, the thermoplastic resin (A) constituting the polymer layer (A) has a volume resistance value in the molten state at a temperature of 15 ° C. higher than its melting point (Tm), and has a volume resistance value of 50 Hz under an AC voltage measuring condition of 0. It is preferably 5 × 10 ⁹ Ω · cm or less. When the volume resistivity value is within this range, the electrostatic charge is strongly applied to the multilayer film during casting, and the adhesion between the cooling drum and the multilayer film is good.

Further, the thermoplastic resin (A) has an average particle size of 0.1 to improve the winding property of the polymer layer (A) separated and separated, and to have the surface property required for each application.
Organic or inorganic fine particles of about 001 to 5.0 μm can be contained at a blending ratio of, for example, 0.01 to 2.0% by weight. Such fine particles include, for example, fumed silica,
Inorganic fine particles such as wet silica, zeolite, calcium carbonate, calcium phosphate, kaolin, kaolinite, clay, talc, titanium oxide, alumina, zirconia, aluminum hydroxide, calcium oxide, graphite, carbon black, zinc oxide, silicon carbide, silver oxide Examples of the organic particles include crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin particles.

If necessary, the thermoplastic resin (A) may include a lubricant, an antioxidant, an antistatic agent, a colorant, a pigment, a tendency brightening agent, a plasticizer, an ultraviolet absorber and other resins. It can be added.

Further, a lubricant is added to the thermoplastic resin (A) in order to adjust the interlayer adhesion between the polymer layer (A) and the polymer layer (B), for example, 0.001% by weight, and more preferably 0. 005 to 0.5 wt% can be blended.
The lubricant may be blended only with the thermoplastic resin (B), or may be blended with both the thermoplastic resin (A) and the thermoplastic resin (B).

The above-mentioned lubricant may be liquid or solid at room temperature, but preferably has a melting point or softening point of 200 ° C. or lower. The following may be mentioned as specific examples of the lubricant, and two or more of these may be used.

A. Aliphatic hydrocarbons: liquid paraffin, microcrystalline wax, natural paraffin, synthetic paraffin, polyethylene wax, polypropylene wax, etc. Higher fatty acid or metal salt thereof: stearic acid, calcium stearate, hydroxystearic acid, hydrogenated oil, sodium montanate, etc. Aliphatic amide: stearamide, oleamide, erucamide, ricinoleamide, behenamide, methylenebisstearamide, etc. Fatty acid esters: n-butyl stearate, methylhydroxystearate, myristyl celloate, high alcohol fatty acid esters, ester waxes, etc. Fatty acid ketone: ketone wax, etc. Fatty alcohol: lauryl alcohol, stearyl alcohol, myristyl alcohol, cetyl alcohol, etc. Partial ester of fatty acid and polyhydric alcohol: glycerin fatty acid ester, hydroxystearic acid triglyceride, sorbitan acid ester, etc. Nonionic surfactants: polyoxyethylene alkyl ether, polyoxyethylene phenyl ether, polyoxyethylene alkyl amide, polyoxyethylene fatty acid ester, etc. Silicon oil: straight-chain methyl silicone oil, methylphenyl silicone oil, modified silicone oil, etc. Fluorosurfactants: fluoroalkyl carboxylic acid, perfluoroalkyl carboxylic acid, monoperfluoroalkyl ethyl phosphate, perfluoroalkyl sulfonic acid salt, etc.

[Thermoplastic Resin (B)] In the present invention,
Thermoplastic resin (B) which is a constituent component of the polymer layer (B)
Is a thermoplastic resin that is substantially incompatible with the polyolefin polymer. Examples of the thermoplastic resin (B) include
Examples thereof include polyester, polyphenylene sulfide, polysulfone, and polyamide. Among these polymers, it is particularly preferable to use a polymer having a solubility parameter (SP value) difference with the polyolefin polymer of 1 or more, particularly 2 or more, to separate and separate the polymer layer (B) from the multilayer film at high speed. Is preferable, and the number of cuts during peeling and separation is reduced, which is preferable.

In particular, when polyester is used as the thermoplastic resin (B), a multilayer film having excellent coextrudability and costretchability with the polyolefin polymer is obtained, which is preferable, and the polyester and the polyolefin polymer have low compatibility. It is preferable because the polyester layer and the polyolefin layer can be peeled from the multilayer film with a relatively small force.

The above-mentioned polyester is a linear polyester composed of a dicarboxylic acid component and a glycol component,
In particular, an aromatic polyester using an aromatic dicarboxylic acid component as the dicarboxylic acid component and an aliphatic diol component having 2 to 10 carbon atoms as the glycol component is preferable.

Examples of the dicarboxylic acid component include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid and 4,4'-diphenyldicarboxylic acid, and particularly terephthalic acid or 2,6-naphthalenedicarboxylic acid. An acid may be preferably mentioned.

As the glycol component, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, neopentyl. Examples thereof include glycol, and particularly ethylene glycol, 1,4
-Butanediol may be preferably mentioned.

Polyester terephthalate, polyethylene-2,6-naphthalene dicarboxylate, or polybutylene terephthalate as the polyester is a polyester layer single layer film exfoliated from the multilayer film, which has excellent mechanical properties and thermal properties. Therefore, it is preferable.

The polyester in the present invention may be either a homopolymer or a copolymer. In the case of a copolymer, a dicarboxylic acid component or a glycol component etc. may be used, for example.
It may be a polyester copolymerized in a proportion of 0 mol% or less, or a polyester obtained by copolymerizing a small amount of a trifunctional or higher polyvalent compound in a range in which the polyester becomes substantially linear (for example, 5 mol% or less). It may be.

In the case of polyethylene terephthalate, the above copolymerization component is isophthalic acid as an acid component, 2,
Examples thereof include 6-naphthalenedicarboxylic acid and 4,4′-diphenylcarboxylic acid, and examples of the glycol component include propylene glycol, 1,4-cyclohexanedimethanol, diethylene glycol, and neopentyl glycol. Also, polyethylene-2,
As the copolymerization component of 6-naphthalene dicarboxylate, terephthalic acid, isophthalic acid, 4,4 as an acid component are used.
Examples of the glycol component include propylene glycol, 1,4-cyclohexanedimethanol, diethylene glycol and neopentyl glycol. As the copolymerization component of polybutylene terephthalate, isophthalic acid, 2,6-naphthalenedicarboxylic acid as an acid component,
4,4'-diphenyldicarboxylic acid and the like, and glycol components include ethylene glycol, 1,
6-hexanediol, propylene glycol, 1,5
-Pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, neopentyl glycol and the like can be mentioned.

In addition to the above-mentioned components, the polyester may be a dicarboxylic acid component such as hexahydroterephthalic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, 1,3-propanediol, polyethylene glycol, etc. , Polytetramethylene glycol,
Glycol components such as dipropylene glycol, triethylene glycol and bisphenol A can be mentioned.

As the above polyester, the above homopolymer and / or copolymer may be used alone, or a blend of these may be used.

As the above polyphenylene sulfide, for example, poly (p-phenylene sulfide) can be preferably mentioned. In this poly (p-phenylene sulfide) (hereinafter sometimes abbreviated as “PPS”), 70 mol% or more, more preferably 85 mol% or more of all repeating units are represented by the following formula. Homopolymers and copolymers consisting of 30 mol% or less, preferably 15 mol% or less, of all repeating units can be composed of repeating units having a copolymerizable sulfide bond. When the proportion of the copolymerization component is too large, the crystallinity and thermal transition temperature of the polymer are lowered, and the heat resistance, dimensional stability and mechanical properties of the film are also lowered.

[0030]

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Examples of the repeating unit having a copolymerizable sulfide bond include repeating units represented by the following formula.

[0032]

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The thermoplastic resin (B) constituting the polymer layer (B) has a volume resistance value in a molten state at a temperature of 15 ° C. higher than its melting point (Tm) of 0.5 at an alternating voltage of 50 Hz. It is preferably × 10 ⁹ Ω · cm or less. When the volume resistivity value is within this range, the electrostatic charge is strongly applied to the multilayer film during casting, and the adhesion between the cooling drum and the multilayer film is good. The polyester having such a volume resistivity value can be obtained, for example, by blending a compound having an alkali metal salt or by copolymerizing a sulfonic acid quaternary phosphonium salt, and is excellent in the multilayer film and the cooling drum. It is possible to obtain excellent adhesion.

Further, the thermoplastic resin (B) has an average particle size of 0.001 in order to improve the winding property of the polymer layer (B) separated and separated, and to provide the surface property required for each application. ~ 5.0 μm organic or inorganic fine particles,
For example, it can be contained at a blending ratio of 0.01 to 2.0% by weight. Examples of such fine particles include dry silica, wet silica, zeolite, calcium carbonate, calcium phosphate, kaolin, kaolinite, clay, talc, titanium oxide, alumina, zirconia, aluminum hydroxide, calcium oxide, graphite, carbon black, zinc oxide, Examples thereof include inorganic particles such as silicon carbide and silver oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin particles.

If necessary, the thermoplastic resin (B) may contain a lubricant, an antioxidant, an antistatic agent, a colorant, a pigment, a tendency brightening agent, a plasticizer, an ultraviolet absorber and other resins. It can be added.

[Multilayer Film] The multilayer film of the present invention is substantially incompatible with at least one polymer layer (A) comprising the thermoplastic resin (A) and the thermoplastic resin (A). At least one layer of the polymer layer (B) made of the thermoplastic resin (B) is adjacent, and the interlayer adhesive force between the two adjacent layers is 0.1 to 20 g / c.
m is a multilayer film in which at least one layer of the polymer layer (B) is present in the outermost layer, and discharge marks of the polymer layer (B) present in the outermost layer obtained by peeling from the multilayer film The number is 5 / m ² or less.

The multilayer film of the present invention has at least one polymer layer (A) (hereinafter sometimes referred to as "A layer") and a polymer layer (B) (hereinafter sometimes referred to as "B layer"). And at least one layer of the polymer layer (B) are present in the outermost layer, the number of layers and the mode are not limited.

The preferred constitution of such a multilayer film is, for example, a two-layer film consisting of B layer / A layer, B layer / A layer /
Examples thereof include a 3-layer film composed of B layer, a 4-layer film composed of B layer / A layer / B layer / A layer, and a 5-layer film composed of B layer / A layer / B layer / A layer / B layer. .

In the multilayer film of the present invention, the interlayer adhesive force of each resin is preferably 0.1 to 20 g / cm, and particularly preferably 0.1 to 10 g / cm. If the interlaminar adhesive strength is less than 0.1 g / cm, peeling or delamination of layers occurs when the film is wound into a roll and stored or conveyed, and wrinkles, tears, or the problem of peeling when unstretched film occurs May occur. Further, if the interlayer adhesive strength exceeds 20 g / cm, the film may be broken or pinholes may be generated when peeling and separating the multilayer film, which is not preferable.

The multilayer film of the present invention may be a non-stretched film, a uniaxially stretched film or a biaxially stretched film, but a biaxially stretched film is particularly preferable because it has excellent mechanical properties. The thickness of the multilayer film is not particularly limited,
For example, in the case of a biaxially stretched film, the total thickness of the multilayer film is preferably 5 to 100 μm, particularly preferably 5 to 50 μm, and the thickness per layer of the B layer is 0.2 to 100 μm.
m, particularly preferably 0.5 to 30 μm, and the thickness of the A layer per layer is 0.5 to 50 μm, particularly 1 to 30.
μm is preferred.

The total ratio of the thickness of the B layer to the total thickness of the multilayer film is preferably 5 to 80%, particularly 15 to 70%.

[Manufacturing Method of Multilayer Film] In the multilayer film of the present invention, for example, a multilayer melt film of A layer and B layer having the above-mentioned constitution is coextruded on a rotary cooling drum, and then the multilayer melt film is placed on a rotary cooling drum. It can be manufactured by applying an electric charge to the melting surface of the multilayer molten film in the vicinity of reaching the temperature, and bringing it into close contact with a rotating cooling drum to cool it.

For example, a polyolefin polymer and a polyester are fed to separate extruders and melted to a temperature of not less than the melting point of each polymer and up to 350 ° C., and each molten polymer is introduced into a conduit or a molding die (die). A non-stretched multilayer film can be produced by merging with the above to make a multilayer state, discharging this from a die, and cooling and solidifying with a cooling drum while applying an electrostatic charge to the discharged film.

In the production of the multilayer film, quaternary phosphonium sulfonate (eg, tetra-n-butylphosphonium 3,5-dicarboxybenzenesulfonate) is added in an amount of 0.001 to 1% by weight, preferably 0.1% by weight. 005
When the polyolefin polymer containing 0.5% by weight is used, the electric resistance of the polyolefin polymer when melted is reduced, so that the electrostatic charge is sufficiently applied to each layer constituting the multilayer film, and the adhesion between the multilayer film and the cooling drum is improved. The property becomes good. Further, the obtained multilayer film has a good hue without defects such as pinholes. Furthermore, it is preferable to blend a sulfone quaternary phosphonium salt also in the polyester because the adhesion between the multilayer film and the cooling drum is further improved.

Generally, it is preferable that the thermoplastic resin (A) material and / or the thermoplastic resin (B) material is dried before being supplied to the extruder. The polyolefin polymer material is not necessarily dried, but a material dried at a temperature of 100 ° C. or higher and lower than the Tm (melting point) of the polyolefin polymer can also be used. The unstretched multilayer film can be further uniaxially or biaxially stretched to obtain a uniaxially stretched multilayer film or a biaxially stretched multilayer film, if necessary. In order to obtain such a uniaxially stretched multilayer film or a biaxially stretched multilayer film, the above unstretched multilayer film is stretched to a temperature (for example, a temperature of Tg (glass transition temperature) or more and Tg + 80 ° C. or less of the thermoplastic resin (B)). Heat and stretch at least uniaxially. The stretching ratio is 2 in the uniaxial direction for a uniaxially stretched multilayer film.
The stretching area ratio is preferably 5 to 50 times in a biaxially stretched multilayer film.
The biaxially stretched multilayer film is produced, for example, by a so-called longitudinal-transverse sequential stretching method in which an unstretched multilayer film is stretched in the machine direction and then in the transverse direction, and a simultaneous biaxial stretching method in which the machine direction and the transverse direction are simultaneously stretched. can do. This biaxially stretched multilayer film can be further restretched in the longitudinal direction or in the uniaxial direction in the transverse direction or in the biaxial directions in the longitudinal direction and the transverse direction to obtain a biaxial restretched multilayer film. The uniaxially stretched multilayer film or the biaxially stretched multilayer film is further heat-treated at a temperature lower than Tm (melting point) of the thermoplastic resin (B) and cooled to room temperature to obtain a uniaxially stretched (heat treated) multilayer film or a biaxially stretched multilayer film. It may be a stretched (heat treated) multilayer film. The uniaxially stretched multilayer film or the biaxially stretched multilayer film thus obtained is, for example, on the surface thereof, for example, Japanese Patent Publication No. 183815/56 or Japanese Examined Patent Publication No.
Surface activation treatment (for example, plasma treatment, amine treatment, corona treatment, etc.) as known from 7-30854 may be applied.

[Use of Multilayer Film] The single-layer film obtained by peeling and separating the polymer layer (A) or the polymer layer (B) from the multilayer film of the present invention can be used for various purposes. For example, a polyester single-layer film having a thickness of 3 μm or less, particularly an ultra-thin single-layer film having a thickness of 1 μm or less is likely to cause breakage in the stretching step, winding failure in the winding step, etc. It can be easily obtained by peeling and separating from the multilayer film of the present invention. Such a polyester single-layer ultrathin film is a capacitor film (for example, a film having a thickness of 3 μm or less) for printer ribbon (for example, a thickness of 5).
It is useful for magnetic recording, especially as a base film for QIC. When the multilayer film of the present invention is used for a laminated capacitor, it can be effectively obtained by vapor-depositing a metal film on the surface of the multilayer film, slitting the film, and then peeling and separating the surface layer on which the metal film is vapor-deposited. Further, the polyolefin single-layer film is a film for capacitors (for example, a film having a thickness of 3 μm or less) and a non-glare film (for example, a film having a thickness of 50 μm or less).
Useful for etc.

Further, the constitution of the multi-layer film is as follows: B layer / A layer /
By using a sandwich structure such as B layer, and separating and separating the B layers of both outer layers from the A layer of the intermediate layer immediately before use,
It is possible to obtain an ultra-clean single-layer A layer film in which the surface oxide film is extremely small and foreign matter is not attached to the surface. Alternatively, the structure of the multi-layer film is B layer / A layer / B
Layer / A layer / B layer sandwich structure, by separating and separating the B layer of the intermediate layer, there is very little oxide film on the surface and ultra clean B layer single layer film with little foreign matter adhering to the surface. Can be obtained. Further, by separating and separating each layer from the biaxially stretched multilayer film of the present invention, a plurality of biaxially stretched monolayer films can be simultaneously obtained with high efficiency and low cost.

[0048]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value was measured by the following method.

1. Volume resistivity of molten resin (impedance) Insert the electrode into the molten resin heated above the melting point of the resin (Tm + 15 ° C), apply an AC voltage of 50Hz, and apply the current value between the electrodes to the volume resistivity of the molten resin. The value was measured.

2. Adhesive Strength A multilayer film was cut into a size of 10 mm in width and 100 mm in length, and the tension (g) applied when the polyester layer was continuously peeled at a peeling angle of 180 ° at a speed of 2 m / min was measured. Average value of this tension and sample width (10 mm)
Adhesive force: T (g / c)
m).

3. Melting point DSC (manufactured by DuPont, V4.OB2000 model) was used to raise the temperature of the sample (10 mg) at a temperature rising rate of 20 ° C./min, and the temperature corresponding to the peak of the endothermic peak accompanying melting was measured. The melting point was used.

4. Glass transition temperature The glass transition temperature was measured by heating the sample (10 mg) at a temperature rising rate of 20 ° C./min using a DSC (V4.OB2000 type device manufactured by DuPont).

5. Charge potential at the time of peeling A multilayer film slit to a width of 300 mm
The surface potential of each of the polyester layer and the polyolefin layer at a position of 200 mm after separation at the time of winding up 50 m at a speed of 300 m / min while separating the layers at a speed of 300 m / min. TI-
300).

6. Discharge trace (flower pattern) A 300 mm wide film peeled and separated from the multilayer film is wound into a roll, the roll is installed in a transport device, and the film is taken out from the roll for 50 m at a speed of 5 m / min. A mist from a humidifier was sprayed on the sample, the number of discharge marks generated at that time was counted, and the value per 1 m ² was taken as the discharge mark generation frequency.

7. Measurement of Small Pimples A film peeled and separated from the multilayer film was wound into a roll, and the entire surface of the roll was visually observed, and the number of protrusions having a size of 1 mmφ or more was counted as a small pimple value.

[Example 1] As a polyester raw material, potassium acetate was added in an amount of 12 mmol% with respect to the dicarboxylic acid component.
Pellets of polyethylene terephthalate having an intrinsic viscosity of 0.60, to which 0.3 wt% of kaolin having an average particle diameter of 0.9 μm was added, were dried at 170 ° C. for 3 hours,
It was supplied to an extruder and melt-extruded at 280 ° C. On the other hand, tetra-n-butylphosphonium 3,5-dicarboxybenzenesulfonate was used as a polyolefin raw material in an amount of 0.05 w.
Using pellets of polypropylene (Tm: 152 ° C., melt flow rate: 5 g / 10 min, polypropylene homopolymer) containing t%, dried at 100 ° C. for 1 hour, and then fed to another extruder to obtain polyethylene terephthalate. Melt extrusion was performed at a similar temperature of 280 ° C. The molten polymers were combined in a die to form a three-layer structure of polyethylene terephthalate / polypropylene / polyethylene terephthalate, which was then discharged from the die and then 20
It was cooled and solidified by winding while applying an electrostatic charge to a cooling drum kept at 0 ° C. to obtain a three-layer unstretched multilayer film. This unstretched multilayer film was brought into contact with a heating roll and heated to 100 ° C., then stretched 3.6 times in the longitudinal direction and immediately cooled to 20 ° C. Subsequently, the film was stretched in the transverse direction using a tenter type transverse stretching device at 100 ° C. by 3.9 times, heat-treated at 210 ° C., cooled to room temperature, and then wound.

The biaxially stretched multilayer film thus obtained had a polyethylene terephthalate layer as an outer layer having a thickness of 5 μm.
m, the thickness of the inner polypropylene layer was 6 μm, and the adhesive force between the polyethylene terephthalate layer and the polypropylene layer was 0.7 g / cm.

The biaxially stretched multi-layer film was formed for 8 hours without any breakage, and the surface potential was measured when the multi-layer film was peeled off and wound up. As a result, the polyethylene terephthalate side was +5 kV and the polypropylene side. Is-
It was 5 kV. In addition, the flower pattern of the wound polyethylene terephthalate film roll was measured and found to be 0 pieces / m ² , and when applying ink as a base film for a thermal transfer printer ribbon, no cissing was observed,
It was a good level.

Example 2 Polyethylene terephthalate pellets similar to those in Example 1 were used as polyester raw materials, and melt-extruded under the same conditions as in Example 1. on the other hand,
As the polyolefin raw material, a random copolymer polypropylene having an ethylene content of 5 mol% containing 0.05 wt% of tetra-n-butylphosphonium 3,5-dicarboxybenzenesulfonate (Tm: 162 ° C., melt flow rate: 7 g / 10 minutes, pellets of 30% ethylene copolymerized polypropylene) and 70% homopolypropylene used in Example 1 were used, dried at 100 ° C. for 1 hour, and then fed to another extruder, the same as polyethylene terephthalate. It was melt extruded at a temperature of 280 ° C. Then, it was cooled and solidified and electrostatically adhered under the same conditions as in Example 1 to obtain an unstretched multilayer film having a three-layer structure of polyethylene terephthalate / polypropylene / polyethylene terephthalate.

The unstretched multilayer film thus obtained was biaxially stretched under the same conditions as in Example 1, and the obtained biaxially stretched multilayer film had an outer polyethylene terephthalate layer thickness of 5 μm and an inner layer as in Example 1. The thickness of the polypropylene layer was 6 μm, and the adhesive force between the polyethylene terephthalate layer and the polypropylene layer was 0.6 g / cm.
Further, when the surface potential was measured when the multilayer film was peeled and wound up, it was -8 on the polyethylene terephthalate side.
kV, +8 kV on the polypropylene side. The flower pattern of the wound polyethylene terephthalate film roll was measured and found to be 3 pieces / m ² , but the application of the ink at a level that is problematic as a base film for a thermal transfer printer ribbon was not observed and was good. It was a good level.

[Example 3] Polyethylene terephthalate and polypropylene, which are the same raw materials as in Example 1, were dried, melted and coextruded under the same conditions as in Example 1, cooled and solidified and electrostatically adhered under the same conditions as in Example 1. , A polyethylene terephthalate / polypropylene two-layer unstretched multilayer film.

The unstretched multilayer film thus obtained was biaxially stretched under the same conditions as in Example 1, and the obtained biaxially stretched multilayer film had a polyethylene terephthalate layer thickness of 5 μm and a polypropylene layer thickness of 6 μm. And the adhesive force between the polyethylene terephthalate layer and the polypropylene layer was 0.6 g / cm. When the surface potential was measured when the multilayer film was peeled off and wound up, the polyethylene terephthalate side was +5 kV and the polypropylene side was -5.
kV. Also, when the flower pattern of the wound polyethylene terephthalate film roll was measured, it was 0 /
It was m ² , and the ink application as a base film for a thermal transfer printer ribbon was at a good level with no flicker.

Example 4 As a polyester raw material,
3,5-dicarboxybenzenesulfonic acid tetra-n-
3 mmol of butylphosphonium to dicarboxylic acid
%, Polyethylene-2,6-naphthalenedicarboxylate (Tm = 263 [deg.] C.) having an intrinsic viscosity of 0.60 in which SiO2 particles having an average particle diameter of 0.12 [mu] m are blended with 0.3% of polyester and 0.03% of calcium carbonate. , Tg = 113
(° C) pellets were dried at 170 ° C for 6 hours, then fed to an extruder and melt-extruded at 300 ° C. On the other hand, the same homopolypropylene pellets containing 0.05 wt% of tetra-n-butylphosphonium 3,5-dicarboxybenzenesulfonate as in Example 1 were used, and both were coextruded in the same manner as in Example 1, An unstretched multilayer film having a three-layer multilayer structure of polyethylene-2,6-naphthalenedicarboxylate / polypropylene / polyethylene-2,6-naphthalenedicarboxylate was prepared.

The unstretched multilayer film thus obtained was heated to 130 ° C. by heating with an infrared heater, and then stretched 4.8 times in the longitudinal direction and immediately cooled to 20 ° C. Then, using a tenter transverse direction stretching device in the transverse direction, 150
After being stretched 5 times at 0 ° C., it was heat treated at 210 ° C., cooled to room temperature and wound up. In addition, the polyethylene of the outer layer
The thickness of the 2,6-naphthalenedicarboxylate layer is 5μ
m, the thickness of the inner polypropylene layer was 6 μm, and the adhesive force between the polyethylene-2,6-naphthalenedicarboxylate layer and the polypropylene layer was 0.6 g / cm. When the surface potential was measured when the multilayer film was peeled off and wound up, it was +5 kV on the polyethylene-2,6-naphthalenedicarboxylate side and -5 kV on the polypropylene side. In addition, wound polyethylene
The small pimples of the 2,6-naphthalene dicarboxylate roll were measured and found to be 3 / roll surface,
The level was sufficiently good as a base film for magnetic recording, especially for QIC.

[Example 5] As a polyester raw material,
3,5-dicarboxybenzenesulfonic acid tetra-n-
3 mmol of butylphosphonium to dicarboxylic acid
%, Polyethylene-2,6-naphthalenedicarboxylate (Tm = 263 [deg.] C.) having an intrinsic viscosity of 0.60 in which SiO2 particles having an average particle size of 0.12 [mu] m are mixed with 0.3% of polyester and calcium carbonate of 0.03% , Tg = 113
(° C) pellets were dried at 170 ° C for 6 hours, then fed to an extruder and melt-extruded at 300 ° C. On the other hand, using the same polypropylene pellets as in Example 1 containing 0.05% by weight of tetra-n-butylphosphonium 3,5-dicarboxybenzenesulfonate,
Both were coextruded in the same manner as in Examples 1 and 2 to give polyethylene-2,6-naphthalenedicarboxylate / polypropylene / polyethylene-2,6-naphthalenedicarboxylate / polypropylene / polyethylene-2,6-.
An unstretched multilayer film having a 5-layer multilayer structure of naphthalene dicarboxylate was prepared.

The unstretched multilayer film thus obtained was stretched and heat-set under the same conditions as in Example 4, cooled to room temperature and then wound. In addition, the polyethylene of the outermost layer and the inner layer
The thickness of the 2,6-naphthalenedicarboxylate layer is 5μ
m, the thickness of the polypropylene layer was 5 μm, and the adhesive force between the polyethylene-2,6-naphthalenedicarboxylate layer and the polypropylene layer was 0.6 g / cm at each layer interface. In addition, when the surface potential was measured when the multi-layer film was separated and separated into five sheets and wound up, polyethylene-2,
The 6-naphthalene dicarboxylate side was +5 kV and the polypropylene side was -5 kV. The small pimples of the wound polyethylene-2,6-naphthalene dicarboxylate roll were measured and found to be 3 rolls / roll surface, which was at a sufficiently good level as a base film for magnetic recording, especially for QIC.

[Comparative Example 1] The polyester raw material and film forming conditions were the same as in Example 1, and the surface potential was measured when peeling and winding a multilayer film using a random copolymer containing 5 mol% of ethylene component as a polyolefin raw material. Was measured, the polyethylene terephthalate side was -25
kV, +20 kV on the polypropylene side. Also,
There were many flower patterns of the wound polyethylene terephthalate film roll, and when ink was applied as a base film for a thermal transfer printer ribbon, repellency and the like occurred and the level was insufficient.

[Comparative Example 2] When the multilayer film was peeled off in Comparative Example 1, static elimination was performed near the peeling point with a static elimination bar, and the surface potential was +1 on the polyethylene terephthalate side.
Although it was as small as kV and polypropylene side-1 kV, the number of flower patterns was still large, and when ink was applied as a base film for a thermal transfer printer ribbon, repellency and the like occurred, which was an insufficient level.

[Comparative Example 3] Polyester raw material and film forming conditions were the same as in Example 1, and as the polyolefin raw material, a mixed polypropylene comprising 70% of a random copolymer containing 5 mol% of ethylene component and 30% of homopolypropylene was used. When the surface potential was measured when the used multilayer film was peeled off and wound up, it was -20 kV on the polyethylene terephthalate side and +20 kV on the polypropylene side. The flower pattern of the wound polyethylene terephthalate film roll was 30 pieces / m ² , which was insufficient when ink was applied as a base film for a thermal transfer printer ribbon, which was insufficient.

[Comparative Example 4] The polyester raw material and film forming conditions were the same as in Example 3, and 30% of a random copolymer containing 5% of ethylene component was used as the polyolefin raw material.
When the surface potential was measured when peeling and winding a multilayer film using a mixed polypropylene in which homopolypropylene was 70%, the polyethylene-2,6-naphthalenedicarboxylate side was -20 kV, and the polypropylene side was +20 kV. . The small pimples of the wound polyethylene terephthalate film roll were measured and found to be 15 rolls / roll surface, which was an insufficient level as a base film for magnetic recording, especially for QIC.

[0071]

EFFECT OF THE INVENTION The thermoplastic resin film obtained by peeling off the multilayer film of the present invention has good chargeability, and there is almost no foreign matter entrained by the charge or discharge marks due to discharge, and the thermal transfer printer ribbon. Ink coatability of the base film for magnetic recording is good, and for magnetic recording especially Q
As a base film for an IC tape, a product roll containing less foreign matter could be obtained.

Claims (5)

[Claims] 1. A polymer layer (A) comprising at least one polymer layer (A) comprising a thermoplastic resin (A) and a polymer layer (B) comprising a thermoplastic resin (B) substantially incompatible with the thermoplastic resin (A). B) is adjacent to at least one layer, and the interlayer adhesion between the two adjacent layers is in the range of 0.1 to 20 g / cm, and at least one layer of the polymer layer (B) is present in the outermost layer. A thermoplastic resin (A)
Is a polyolefin polymer in which the proportion of the copolymerization component is 3 mol% or less, and the number of discharge marks of the polymer layer (B) existing in the outermost layer obtained by peeling from the multilayer film is 5 / m.
A multi-layer film which is ² or less. 2. The multilayer film according to claim 1, wherein the multilayer film is a film having three or more layers in which the polymer layers (A) and the polymer layers (B) are alternately present. 3. The multilayer film according to claim 1, wherein the thermoplastic resin (A) is a polypropylene homopolymer. 4. The multilayer film according to claim 1, wherein the thermoplastic resin (B) is polyester. 5. The multilayer film according to claim 1, which is used for producing a thermoplastic resin (B) film by peeling and separating the polymer layer (B) from the multilayer film.