JPH10329285A - Multi-layer stretched film - Google Patents

Abstract

(57) [Summary] (Problem corrected) [Problem] A multilayer stretched film excellent in productivity, stretchability, quality, cost, etc., and having no or few surface defects due to transfer of a first polymer layer, and the multilayer stretched film To provide a stretched film of the first polymer layer having no or few surface defects peeled from the first polymer layer. SOLUTION: At least one layer of a first polymer layer made of a thermoplastic resin and at least one layer of a second polymer layer made of a thermoplastic resin incompatible with the polymer layer are adjacent to each other, and at least one of an outermost layer is formed. A multilayer film in which one layer is composed of a first polymer layer and a second polymer layer and a first polymer layer are present alternately, wherein the resin constituting the second polymer layer is silica having a specific particle size and / or An olefin polymer containing silicone resin particles, a multilayer stretched film, and a stretched thermoplastic resin film comprising a first polymer layer obtained by peeling the multilayer stretched film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily peelable multilayer stretched film in which mutually incompatible polymer layers are laminated adjacently and a thermoplastic resin film (single-layer film) peeled and separated therefrom, and more particularly to a high-speed production of a film. The film is possible, the number of discharge marks due to peeling electrification is small, the number of fish eyes is small, the stretchable multi-layer stretched film excellent in stretchability and the thermoplastic resin stretched film peeled from it, with few transfer defects from adjacent layers About.

[0002]

2. Description of the Related Art Thin films for heat-sensitive stencil printing and condensers are easily cut in the processing process, so a carrier film of a material incompatible with a product film is laminated and reinforced for processing. After completion, the processed product film is peeled off from the carrier film and wound up to reduce cutting (Japanese Patent Laid-Open No. 64-1409).
No. 2, JP-A-04-7198).

Further, in order to produce general-purpose films and magnetic recording films with high productivity, coextruded polymers which are incompatible with each other to form an unstretched film, and at least uniaxially stretched and then peeled off to obtain a product film. 2 at a time
Method of forming more than one film (JP-A-51-30862, JP-A-56-113427, JP-A-58-5226, etc.)
Has been proposed. However, according to the knowledge of the present inventor, in this method, when the multilayer film is peeled off, peeling charging occurs, and a discharge mark is generated on a film to be a product, and the discharge mark is, for example, a film for a thermal transfer printer ribbon or a magnetic recording medium. It causes repelling when applying paint to film for use. Further, the present inventor has previously found that it is effective to add specific particles to the second polymer layer in order to prevent the discharge traces. It has been considered that the MFR of the polyolefin is preferably 30 g / 10 min or less in order to deteriorate the surface properties and abrasionability of the first polymer layer as an effect of the agent.

Further, the above-mentioned method requires that the quality (purity), stretchability, and the like of the resins constituting the first polymer layer and the second polymer layer are equal. For example, polyester is added to the resin of the first polymer layer, (2) When a polyolefin is used as the resin of the polymer layer (reinforcing layer), if a large or a large number of foreign substances (gel foreign substances) are present in the polyolefin, the foreign substances are peeled from the formed multilayer stretched film to obtain a stretched polyester film. It is necessary to reduce foreign matters in the polyolefin as much as possible because of adverse effects as transfer defects.

[0005] As measures against the transfer defect, it is conceivable to enhance the cleanliness of the polyolefin production process or to reduce foreign substances contained in the polymer itself. But,
It is difficult to eliminate gels in polyolefins under production conditions. Therefore, attempts were made to reduce the removal of gel foreign matter by polymer filtration.However, when trying to increase the filtration accuracy, the filtration speed was reduced and the filtration pressure was significantly increased, while when the filtration accuracy was reduced, the film quality was reduced. The measures were not sufficient in terms of productivity, and were not sufficient for, for example, more severe thermal transfer printer ribbons, high-sensitivity stencils, condensers, and magnetic recording applications.

[0006]

SUMMARY OF THE INVENTION The first object of the present invention is to improve the above-mentioned drawbacks, namely, a discharge mark due to charging at the time of peeling, and to further remove a first polymer layer and a second polymer layer from a multilayer stretched film. It is an object of the present invention to provide an easily peelable multilayer stretched film capable of producing a stretched film comprising a first polymer layer having no or few surface defects on a product with good productivity.

[0007] A second object of the present invention is to provide a stretched film comprising a first polymer layer which improves discharge traces due to charging at the time of peeling and has no or few surface defects on a product peeled from a multilayer stretched film. It is in.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have used a polyolefin-based polymer in which specific particles are added to the second polymer layer. By specifying the addition amount in a specific range, even if the MFR of the polymer is large, it is possible to prevent the influence on the surface property and the shaving property on the first polymer layer, and to produce a high-quality multilayer stretched film with high productivity. It is possible to use a polymer having a large MFR for the second polymer layer by increasing the filtration accuracy with respect to transfer defects from the second polymer layer, and peeling off from the multilayer stretched film. It is known that the stretched film of the first polymer layer obtained has good stretchability and thickness unevenness, and has no or little discharge marks due to peeling charging and surface defects due to transfer. And, we have reached the present invention.

That is, according to the present invention, at least one layer of a first polymer layer made of a thermoplastic resin and at least one layer of a second polymer layer made of a thermoplastic resin incompatible with the polymer layer are adjacent to each other. The interlayer adhesion between these two layers is in the range of 0.1 to 20 g / cm, at least one of the outermost layers is composed of the first polymer layer, and the second polymer layer and the first polymer layer are present alternately. A multilayer film, wherein the resin constituting the second polymer layer has a melt flow rate (MFR) of 30 to 50 g / 10 min and is selected from silica and crosslinked silicone resin particles having an average particle size of 0.01 to 2 μm. 0.01% of at least one kind of fine particles
An olefin-based polymer containing up to 5% by weight;
Preferably, when the first polymer layer and the second polymer are peeled off, the number of discharge marks on the surface of the first polymer layer is 5 / m ² or less.
0 to 50 fish eyes of μm or more / 3000cm
² , preferably the olefin-based polymer is a homopolymer or copolymer of an α-olefin having 2 to 10 carbon atoms, and preferably the second polymer layer is formed by a filter having an average opening of 35 μm or less during melt extrusion. It is a multilayer stretched film characterized in that it has been filtered.

The present invention is also a stretched thermoplastic resin film comprising a first polymer layer obtained by peeling from the multilayer stretched film.

In the present invention, the thermoplastic resin constituting the second polymer layer has a melt flow rate (MFR) of 30.
~ 50 g / 10 min polyolefin polymer,
It is preferably an α-polyolefin polymer having 2 to 10 carbon atoms, and more preferably a melting point (Tm) of 100 to 1
70 ° C ethylene copolymerized polypropylene or melting point (T
m) is polymethylpentene at 230 to 240 ° C.
If the MFR is less than 30 g / 10 min, the pressure of the fine filter increases, so that when performing thick film formation or high-speed film formation, extrusion is not performed at a high discharge rate. The filter pressure and extrusion pressure increase, leading to filter breakage and overload of the extruder.
The filtration pressure can be reduced by increasing the number of filters, but this increases the cost and limits the filter housing. On the other hand, if the MFR is more than 50 g / 10 min, the melt viscosity becomes too low, so that the extrusion pressure cannot be increased and the ejection becomes unstable. Preferred MFR is 3
1 to 40 g / 10 minutes. It is preferable to use a copolymer in a region having a high MFR from the viewpoint of stretchability.

The ethylene copolymerized polypropylene preferably has an ethylene copolymerization amount of 1 to 20 mol%. When this range is not satisfied, the stretchability is inferior as in the case of homopolypropylene and polyethylene. For example, the stretchability is poor when biaxially stretched, the thickness unevenness is poor, and cutting frequently occurs. The copolymer structure is not particularly limited as long as it is an ethylene-propylene copolymer, but a random copolymer and a block copolymer are preferable. Further, from the viewpoint of film surface properties, random copolymerized polypropylene is particularly preferred. Further, it is preferable that the amount of foreign substances in the raw material is as small as possible in order to reduce the increase in pressure over time due to filtration of the filter and extend the life.

The olefin polymer according to the present invention comprises:
Average particle size of 0.01 to 2 μm for improvement of discharge marks due to peeling charging of the film peeled and separated from the multilayer stretched film
At least one particle selected from the group consisting of silica and cross-linked silicone resin particles. Of these, silica is particularly preferred.

Examples of the silica include dry silica and wet silica. Further, as the crosslinked silicone resin fine particles, the following formula (1)

[0015]

## STR1 ## RSiO _3/2 ····· (1) (where, R represents at least one type is consisting of alkyl groups and phenyl groups having 1 to 6 carbon atoms) bonding units 80 wt%, represented by The particles are preferably silicone resin particles as described above.

The above-mentioned bonding unit means the following bonding formula (2).

[0017]

Embedded image Here, R is the same as above.

A method for producing the crosslinked silicone resin fine particles is known, for example, a method of hydrolyzing and condensing an organotrialkoxysilane (for example, Japanese Patent Publication No. 40-149).
No. 17, Japanese Patent Publication No. 22767/1995) and a method for producing polymethylsilsesquioxane fine particles using methyltrichlorosilane as a starting material (for example, Belgian Patent No. 572).
No. 412). However, in the present invention, the production method is not limited, and the crosslinked silicone resin fine particles produced by any method may be used.

R in the above formula (1) or the bonding formula (2) is at least one of an alkyl group having 1 to 6 carbon atoms and a phenyl group. Examples of the alkyl group include methyl, ethyl, propyl, butyl and pentyl. , Hexyl and the like. These can be one or more. When R is plural, for example, when it is methyl and ethyl, a mixture of methyltrimethoxysilane and ethyltrimethoxysilane can be produced as a starting material. However, in consideration of the production cost, the ease of the synthesis method, and the like, silicone resin (polymethylsilsesquioxane) particles in which R is methyl are preferable. The crosslinked silicone resin particles may have any shape, but are preferably substantially spherical.

The olefin polymer of the present invention comprises:
When casting a multilayer film, a quaternary phosphonium sulfonic acid salt is used in an amount of 0.001 to 0.003 to ensure sufficient electrostatic adhesion of the film to a casting drum.
It is preferable to contain 1 wt%. The olefin-based polymer has a melting point (T.sub.T) of the thermoplastic resin constituting the first layer.
m), the volume resistivity in the molten state at a temperature higher by 15 ° C.
It is preferably 0.5 × 10 ⁹ Ω · cm or less. When the volume resistivity is in this range, the application of electrostatic charge to the multilayer film during casting becomes strong, and the adhesion between the cooling drum and the multilayer film becomes good.

In order to further improve the winding property of a film made of the polyolefin polymer, an organic material having an average particle size of about 0.001 to 2.0 μm other than silica and crosslinked silicone resin fine particles is used. And inorganic fine particles can be blended and contained at a ratio of, for example, 0.01 to 3.0 wt%. As such fine particles,
For example, inorganic fine particles such as 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, Organic particles such as crosslinked acrylic resin particles, crosslinked polystyrene resin particles, and melamine resin particles can be used.

The polyolefin polymer may contain, if necessary, an antioxidant, an antistatic agent, a coloring agent, a pigment,
A tendency brightener, a plasticizer, an ultraviolet absorber, other resins and the like can be added.

In the present invention, it is preferable to use a resin such as polyester, polyphenyl sulfide (PPS) or polysulfone polyolefin as the thermoplastic resin constituting the first polymer layer. Of these, polyesters are particularly preferred.

The polyester is a linear polyester comprising a dicarboxylic acid component and a glycol component. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and diphenyletherdicarboxylic acid. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred.

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 Glycol and the like. Among these, ethylene glycol and 1,4-butanediol are preferred, and ethylene glycol is particularly preferred.

Among these polyesters, polyethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polybutylene terephthalate, polyhexamethylene terephthalate and a copolymer thereof are obtained by separating a polyester layer (single layer) from a multilayer stretched film. This is preferable because the film) has excellent mechanical properties and thermal properties. Furthermore, since polyethylene-2,6-naphthalenedicarboxylate has a high stretching temperature and a high stretching stress, it has the advantage that the polymer type and stretching conditions of the second polymer layer that can be selected can be widened.

The above-mentioned polyethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate,
The polybutylene terephthalate and the polyhexamethylene terephthalate may each be a polyester obtained by copolymerizing a dicarboxylic acid component or a glycol component at a ratio of, for example, 10 mol% or less. A polyester copolymerized in a small amount within a linear range (for example, 5 mol% or less) may be used.

When the copolymerization component is polyethylene terephthalate, isophthalic acid, 2,6
-Naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, etc., and propylene glycol, 1,4-butanediol,
4-cyclohexanedimethanol, diethylene glycol, neopentyl glycol and the like can be mentioned.
Examples of the copolymer component of polyethylene-2,6-naphthalenedicarboxylate include terephthalic acid, isophthalic acid, and 4,4′-diphenyldicarboxylic acid as an acid component, and 1,4-butanediol as a glycol component. Examples thereof include 1,6-hexanediol, propylene glycol, 1,5-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, and neopentyl glycol. As a copolymer component of polybutylene terephthalate, isophthalic acid, 2,6-naphthalenedicarboxylic acid,
4′-diphenyldicarboxylic acid and the like,
As the glycol component, ethylene glycol, 1,6-hexanediol, propylene glycol, 1,5-pentanediol, 1,4-cyclohexanedimethanol,
Examples thereof include diethylene glycol and neopentyl glycol. Examples of the copolymerization component of polyhexamethylene terephthalate include isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid and the like as an acid component, and ethylene glycol, Examples thereof include 4-butanediol, propylene glycol, 1,5-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, neopentyl glycol and the like.

As the copolymerization component of polyethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polybutylene terephthalate and polyhexamethylene terephthalate, for example, hexahydroterephthalic acid, adipic acid, sebacic acid,
A dicarboxylic acid component such as dodecanedicarboxylic acid;
Glycol components such as propanediol, polyethylene glycol, polytetramethylene glycol, dipropylene glycol, triethylene glycol, and an alkylene oxide adduct of bisphenol A can be mentioned.

As the above polyester, a homopolymer or a copolymer can be used, and a blend of these polyesters can also be used.

The thermoplastic resin constituting the first polymer layer has a volume resistance in a molten state at a temperature higher by 15 ° C. than the melting point (Tm) of 0.5 × 10 ⁹ Ω · cm under the measurement condition of an AC voltage of 50 Hz. The following is preferred. When the volume resistivity is in this range, the application of electrostatic charge to the multilayer film during casting becomes strong, and the adhesion between the cooling drum and the multilayer film becomes good. A thermoplastic resin having such a volume resistivity, particularly a polyester, can be obtained by, for example, blending a compound having an alkali metal salt or blending or copolymerizing a quaternary phosphonium salt of sulfonic acid, and a multilayer film. Good adhesion to the cooling drum can be obtained.

The thermoplastic resin of the first polymer layer has an average particle size of 0.001 to improve the winding property of the peeled / separated film and to provide the surface property required for each application. It is preferable to mix and contain organic or inorganic fine particles of about 5.0 to 5.0 μm in a ratio of, for example, 0.01 to 3.0 wt%. Such fine particles include, for example, dry silica, wet silica, zeolite, calcium carbonate,
Calcium phosphate, kaolin, kaolinite, clay,
Inorganic fine particles such as talc, titanium oxide, alumina, zirconia, aluminum hydroxide, calcium oxide, graphite, carbon black, zinc oxide, silicon carbide, silver oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, crosslinked silicone Organic particles such as resin particles can be used. Further, a lubricant, an antioxidant, an antistatic agent, a colorant, a pigment, a tendency brightener, a plasticizer, an ultraviolet absorber, other resins, and the like may be added to the first polymer layer as needed. it can. Even if silica or crosslinked silicone resin particles are contained in the first polymer layer, these particles do not contribute to the reduction of discharge marks due to peeling charging.

The multilayer stretched film according to the present invention comprises:
The number of layers is not particularly limited as long as at least one of the polymer layers and at least one of the second polymer layers are adjacent and at least one of the outermost layers is composed of the first polymer layer. However, when the film is a multilayer film having three or more layers, the first and second polymer layers are alternately provided. A specific example of this layer configuration will be described in the case where the first polymer layer is made of polyester (E layer) and the second polymer layer is made of ethylene copolymerized polyolefin (O layer). Film, E layer / O layer / E
Three-layer film consisting of layers, E layer / O layer / E layer / O layer / E
Preferable examples include a five-layer film composed of layers. Among them, a three-layer film composed of E layer / O layer / E layer is particularly preferable.

The multilayer stretched film according to the present invention has an interlayer adhesion between the first polymer layer and the second polymer layer of 0.1 to 20.
g / cm, and particularly preferably 0.1 to 10 g / cm. If the interlayer adhesion is less than 0.1 g / cm, delamination or delamination occurs when storing and transporting the multilayer stretched film in a roll, causing troubles such as wrinkles and tears, and stretching. A trouble that the multilayer film peels off before being subjected to the treatment may occur. On the other hand, if the interlayer adhesive strength exceeds 20 g / cm, the interlayer adhesive strength is so strong that the film is broken or a pinhole is formed when the multilayer stretched film is peeled or separated, which is not preferable.

The multilayer stretched film in the present invention may be either a uniaxially stretched film or a biaxially stretched film.
Particularly, a biaxially stretched film is preferable because of excellent mechanical properties in the biaxial direction. The thickness of the multilayer stretched film is preferably determined by the stretching stress of the first polymer layer and the second polymer layer. The range is, for example, in the case of a biaxially stretched film, the total thickness of the multilayer stretched film is 3 to 100 μm, especially 5 to 50 μm, the thickness per layer of the second polymer layer is 0.2 to 80 μm, especially 0.5 to 30 μm,
The thickness per layer of the first polymer layer is 0.5 to 50 μm
m, especially 1 to 30 μm, when peeling / separating,
It is preferable in terms of productivity and equipment cost. In the case of a uniaxially stretched film, the total thickness of the multilayer stretched film is 15 to
300 μm, especially 15 to 150 μm, and the thickness per layer of the second polymer layer is 0.6 to 250 μm, especially 1.
It is preferably from 5 to 90 μm, and the thickness per one layer of the first polymer layer is preferably from 1.5 to 150 μm, particularly preferably from 3 to 90 μm from the viewpoint of productivity and equipment cost.

At the time of film formation, it is preferable to use a filter having an average aperture of 35 μm or less in order to remove foreign matter in the second polymer layer. In this case, 50 fish eyes having a diameter of 90 μm or more / 50 fish eyes / 3000 cm It can be suppressed to ² or less. In particular, in order to make the fish eye almost zero, it is preferable that the average aperture is further finely set to 28 μm or less.

The material of the filter may be metal or ceramic, but stainless steel is preferable because it can be recycled. The filter may be manufactured in any of a mesh type, a non-woven cloth type, a sintered type, and the like.

[0038] The polyolefin-based polymer includes
In order to adjust the adhesive strength with the polymer layer, for example, 0.001% by weight of a lubricant, further 0.005 to 0.5% by weight
Can be blended.

The lubricant may be liquid or solid at room temperature, but preferably has a melting point or softening point of 200 ° C. or less. Specific examples of the lubricant include the following, 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 acids or metal salts 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.

In the production of the multilayer stretched film in the present invention, first, a multilayer molten film of a thermoplastic resin, particularly polyester, forming the first polymer layer and a polyolefin-based polymer forming the second polymer layer adjacent thereto is rolled on a rotary cooling drum. The film is co-extruded on top, and then the film is brought into close contact with a rotary cooling drum and cooled to obtain an unstretched multilayer film. In this case, the thermoplastic resin and the polyolefin-based polymer forming the first polymer layer are preferably each made of a quaternary phosphonium sulfonic acid salt in an amount of 0.001 to 1.
wt%, and an electrostatic charge is applied to the melted surface of the multilayer molten film in a non-contact manner in the vicinity where the multilayer molten film reaches the rotating cooling drum. For example, ethylene copolymerized polypropylene and polyester are supplied to separate extruders and melted at a temperature not lower than the melting point of each polymer and up to 350 ° C., preferably at the same temperature.
m), the molten polymers are combined in a conduit or a molding die (die) to form a multi-layered state, which is discharged from the die, and furthermore, an electrostatic charge is applied to the discharged film to form a cooling drum. An unstretched multilayer film can be manufactured by cooling and solidifying while being in close contact with the film. This unstretched multilayer film may have any number of layers as long as the multilayer film has two or more adjacent first and second polymer layers. In addition, it is preferable to dry a thermoplastic resin raw material before supplying to an extruder. Of course, the olefin-based polymer constituting the second polymer layer does not necessarily need to be dried.
It is preferable to use one dried at a temperature lower than Tm (melting point). The unstretched multilayer film is further stretched in a uniaxial or biaxial direction to form a uniaxially stretched multilayer film or a biaxially stretched multilayer film. In order to obtain such a uniaxially stretched multilayer film or a biaxially stretched multilayer film, a temperature at which the unstretched multilayer film can be stretched (for example, Tg (glass transition temperature) of a thermoplastic resin or higher, Tg + 80 ° C.)
And the film is stretched in at least one direction.
In the case of a uniaxially stretched multilayer film, the stretching ratio is preferably 2 to 12 times in the uniaxial direction, and in the case of a biaxially stretched multilayer film, it is 2.5 times or more, preferably 3 times or more in the uniaxial direction. It is preferable to set it to 40 times.
The biaxially stretched multilayer film is, for example, a non-stretched multilayer film stretched in the machine direction, and then stretched in the transverse direction.
It can be manufactured by a transverse sequential stretching method or a simultaneous biaxial stretching method of stretching simultaneously in the machine direction and the transverse direction. The biaxially stretched multilayer film can be further re-stretched in the longitudinal or transverse uniaxial direction, or in the longitudinal and transverse biaxial directions to form a biaxially stretched multilayer film. The uniaxially stretched multilayer film or biaxially stretched multilayer film,
Furthermore, heat treatment is performed at a temperature lower than the melting point (Tm) of the thermoplastic resin of the first polymer layer, preferably at a temperature lower than Tm (Tm−220) ° C. or higher, and then cooled to room temperature. More preferably, it is heat-treated at a temperature lower than the melting point (Tm) of the olefin-based polymer, preferably at a temperature lower than Tm (Tm-120) ° C. or higher, and then cooled to room temperature. Thereby, a uniaxially stretched (heat-treated) multilayer film or a biaxially stretched (heat-treated) multilayer film can be obtained without completely relaxing the molecular orientation due to the stretching treatment of the second polymer layer. The thus obtained uniaxially stretched multilayer film or biaxially stretched multilayer film is coated on its surface with, for example,
A surface activation treatment (for example, a plasma treatment, an amine treatment, a corona treatment, etc.) as known in JP-A-183815 and JP-B-57-30854 may be applied.

The multilayer stretched film of the present invention may be used as it is as a multilayer stretched film. However, it is preferable to separate and separate the first polymer layer or the second polymer layer and use the obtained single-layer stretched film for various purposes. preferable. For example, a polyester single-layer stretched film having a thickness of 3 μm or less, particularly 1 μm
m or thinner single-layer stretched film is liable to cause breakage or poor winding in the stretching process, and the single-layer stretched film has a disadvantage of lowering the production yield. Then, if the film is separated and separated into a single-layer stretched film, an ultrathin film can be easily obtained. In addition, although the ultrathin film is not easy to handle even on the handling surface, in the multilayer stretched film of the present invention, handling is required as a multilayer stretched film in a processing step that requires handling, and the handleability is improved by peeling and separating after processing. Can be.

The stretched polyester single-layer film peeled from the multilayer stretched film of the present invention has few surface defects, and has a capacitor film (for example, a film having a thickness of 3 μm or less) and a film for a printer ribbon (for example, a thickness of 5 μm)
This is also useful for applications that minimize surface defects such as base films for thermal stencil printing, magnetic recording, especially QIC. When the multilayer stretched film of the present invention is used for a multilayer capacitor, it can be effectively obtained by depositing a metal film on the surface of the multilayer stretched film, slitting the film, and separating the surface layer on which the metal film is deposited. Also,
The polyolefin monolayer film is useful for a capacitor film (for example, a film having a thickness of 3 μm or less), a non-glare film (for example, a film having a thickness of 50 μm or less), and the like. Furthermore, when used as a heat-sensitive stencil printing film, by separating and peeling after attaching a porous support such as Japanese paper on both sides of the multilayer stretched film, handling properties can be improved, and process breaks can be eliminated. . At this time, the heat shrinkage of the heat-sensitive stencil film needs to be appropriately large, but when the heat setting temperature is low, this is satisfied.

The structure of the multilayer stretched film is E layer / O layer / E
By forming a sandwich structure such as a layer and separating and separating the outer layers E from the intermediate layer O immediately before use, an ultra-clean O 2 film with very little oxide film on the surface and little adhesion of foreign matter to the surface is obtained. A single-layer film can be obtained. Furthermore, the configuration of the multilayer stretched film is changed to E layer / O layer /
5 layers sandwich structure such as E layer / O layer / E layer,
By peeling and separating the E layer of the intermediate layer, it is possible to obtain an ultra-clean polyester (E layer) single-layer film having an extremely small amount of an oxide film on the surface and little adhesion of foreign matter on the surface. Further, by separating and separating each layer from the biaxially stretched multilayer film of the present invention, two or more biaxially stretched single-layer films can be obtained at the same time, resulting in high efficiency and low cost. be able to.

[0044]

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. Melt flow rate (MFR) Measured at a temperature of 230 ° C and a test load of 2.16 kgf based on JIS K6758.

2. Fish eye A film with a surface area of 3,000 cm ² is marked on the fish eye with a polariscope using a deflecting plate, and the fish eye detected by a transmission optical microscope is observed. If the diameter of the defect (including voids) is 90 μm or more, Count the number of fish eyes.

3. 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).

4. Discharge mark (flower pattern) A 300 mm wide film peeled and separated from the multilayer film is wound into a roll, and the roll is set on a transport device, and the film is taken out from the roll at a speed of 5 m / min for 50 m, and the taken out film is taken out. Spray the mist with a humidifier, count the number of discharge traces generated at that time,
The value per 1 m ² is defined as the frequency of occurrence of discharge marks.

5. Transfer Defects A film having a surface area of 3,000 cm ² is marked as a defect with a polariscope using a deflection plate, and the diameter (including voids) of each defect is 90 μm or more with a transmission optical microscope. Defects having no internal nucleus, which is a characteristic, are counted, and are used as the number of transfer defects.

6. Thickness The thickness used for calculating the stretching tension is measured by a gravimetric method for the film obtained by peeling and separating the multilayer stretched film.

7. Adhesive strength film width 10mm, chuck spacing 100mm,
The tension (g) applied when the first polymer layer is peeled off from the second polymer layer at a peel angle of 180 degrees at a speed of 2 m / min is measured. Average value of this tension and sample width (10mm)
The adhesive force: T (g / c)
m).

8. Melting point The temperature corresponding to the top of the endothermic peak accompanying melting when a sample (10 mg) was heated at a heating rate of 20 ° C./min using DSC (V4.OB2000 model manufactured by DuPont). Determine the melting point.

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

10. Surface Properties (Surface Roughness Ra) The center line average roughness (Ra) is measured according to JIS B0601. That is, using a stylus type surface roughness meter manufactured by Kosaka Laboratory Co., Ltd., a chart (film surface roughness curve) was drawn under the conditions of a needle radius of 2 μm and a load of 0.07 g to obtain a film surface. When a portion of the measured length L is extracted from the roughness curve in the direction of its center line, and the center line of the extracted portion is defined as the X axis, and expressed by a roughness curve Y = f (X), a value given by the following equation (Ra: μm) is defined as the surface roughness (Ra). In the present invention, Ra is represented as an average value of five pieces measured by removing eight pieces from the larger value with the reference length being 0.25 mm.

[0055]

(Equation 1)

11. Sharpness The first polymer layer film having a width of 10 mm, which has been peeled off from the multilayer film and wound up, has a speed of 10 m / min and a tension of 50.
Run 200m while rubbing the SUS pin with g
The amount of shavings attached to the S pin was evaluated on a 5-point scale. 1st grade: no shavings adhered at all 2nd grade: same amount of shavings as when running a single-layer film with the same composition and the same stretching conditions as the first polymer layer 3rd grade: 2-3 times of 2nd grade Shaved powder adheres over the width of 4th grade: Shaved powder adheres over 3 to 4 times the width of 2nd grade 5th grade: Shaved powder adheres over a width of 4th grade or more

Example 1 As the first polymer, 3,5-
Polyethylene terephthalate having an intrinsic viscosity of 0.60 (Tm = 3), in which tetra-n-butylphosphonium dicarboxybenzenesulfonate is blended with 3 mmol% with respect to the dicarboxylic acid component and 0.3 wt% of kaolin particles with an average particle diameter of 0.9 μm with respect to polyester. The pellets (256 ° C., Tg = 68 ° C.) were dried at 170 ° C. for 3 hours, then supplied to an extruder and melt-extruded at 280 ° C.

On the other hand, a copolymerization ratio containing 0.05 wt% of tetra-n-butylphosphonium 3,5-dicarboxybenzenesulfonate and 0.15 wt% of amorphous silica having an average particle diameter of 0.3 μm as the second polymer. 4%, MF
A pellet of ethylene-propylene random copolymerized polypropylene (R40g / 10 min) was dried at 100 ° C. for 1 hour, and then supplied to another extruder to form a stainless sintered type having an average aperture of 35 μm and a diameter of 12 inches. The mixture was melt-extruded at 280 ° C. and 200 kg / hr through 30 filters.

The respective molten polymers are merged in a die to form a three-layered multilayer structure of polyethylene terephthalate / ethylene copolymerized polypropylene / polyethylene terephthalate, then discharged from a die, and then charged on a cooling drum maintained at 30 ° C. Was applied and brought into close contact to cool and solidify to obtain a three-layer unstretched multilayer film.

Next, the unstretched multilayer film was heated to 100 ° C. by heating with an infrared heater, stretched 4.0 times in the longitudinal direction (longitudinal direction), and immediately cooled to 20 ° C. Subsequently, the film was stretched four times at 100 ° C. using a tenter transverse stretching machine in the transverse direction, heat-set at 220 ° C., cooled to room temperature, and wound up.

The resulting biaxially stretched multilayer film had a polyethylene terephthalate layer thickness of 5.0 μm and an ethylene copolymerized polypropylene layer thickness of 6.0 μm. The multilayer has no number of discharge traces of the polyethylene terephthalate layer peeled from the multilayer stretched film,
The fisheye of the ethylene copolymerized polypropylene layer was measured to be 45 pieces / 3000 cm ² , and the transfer defect of the peeled polyethylene terephthalate layer was 18 pieces / 3.
At a level of 000 cm ² , there was no problem. The filter pressure was also 70 kg / cm ² (the extrusion pressure at this time was 1 kg).
20 kg / cm ² ), good high-speed film-forming properties, and no thickness unevenness or cutting due to stretching.

[Examples 2 to 9] Films were formed under the conditions shown in Table 1. As a result, the surface properties, abrasion, discharge marks, transfer defects, and uneven thickness were good. Sufficient properties were obtained as a recording film.

[0063]

[Table 1]

[Comparative Examples 1 to 6] Except as shown in Table 2, a film was formed in the same manner as in Example 1;
There were defects in any of discharge marks, transfer defects, and thickness irregularities, and the characteristics were insufficient as a film for a thermal printer ribbon or a film for magnetic recording.

[0065]

[Table 2]

[0066]

According to the present invention, when the first polymer layer and the second polymer layer are separated by adding silica and / or crosslinked silicone resin particles to the carrier layer (second polymer layer) of the multilayer stretched film. The number of generated discharge traces can be reduced. In addition, the silica, the particle size of the crosslinked silicone resin particles, by setting the amount added to a specific range,
Since the change in the surface properties of the first polymer layer due to the transfer can be suppressed, and the fineness of the filter can reduce the fish eyes of the second polymer layer and reduce the transfer to the first polymer layer. The melt viscosity (MFR) of the material constituting the corresponding layer can be increased, and the productivity can be improved. Further, by using ethylene copolymerized polypropylene and polymethylpentene, high stretchability can be ensured and productivity can be improved. In particular, when used as a film for condensers, high-sensitivity stencil printing films, films for thermal transfer printer ribbons, and films for magnetic recording, discharge marks and transfer defects are improved, productivity is improved at high discharge, and unevenness in thickness due to stretching is improved. A good film can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 23:00 B29L 7:00 9:00

Claims (11)

[Claims] At least one layer of a first polymer layer made of a thermoplastic resin and at least one layer of a second polymer layer made of a thermoplastic resin incompatible with the polymer layer are adjacent to each other. Has an interlayer adhesion of 0.1 to 20 g / c
m, at least one of the outermost layers is a first polymer layer, and the second polymer layer is a multilayer film in which the second polymer layer and the first polymer layer are alternately present. Melt flow rate (MFR) is 30 ~
50 g / 10 min and an average particle size of 0.01 to 2 μm
A multilayer stretched film, characterized in that it is an olefin-based polymer containing 0.01 to 5% by weight of at least one kind of particles selected from silica and crosslinked silicone resin particles. 2. The multilayer stretched film according to claim 1, wherein when the first polymer layer and the second polymer layer are peeled off, the number of discharge marks on the surface of the first polymer layer is 5 / m ² or less. 3. The multilayer stretched film according to claim 1, wherein the number of fish eyes having a diameter of 90 μm or more in the second polymer layer is 0 to 50/3000 cm ² . 4. An olefin-based polymer having 2 to 10 carbon atoms.
The multilayer stretched film according to claim 1 or 3, which is a homopolymer or copolymer of α-olefin of the above (1). 5. An olefin polymer having a melting point (Tm) of 1
The multilayer laminated film according to claim 1, 3 or 4, which is an ethylene-propylene copolymer having a temperature of from 00C to 170C. 6. An olefin polymer having a melting point (Tm) of 2
A polymethylpentene having a temperature of 30 to 240 ° C.
5. The multilayer laminated film according to 3 or 4. 7. The multilayer stretched film according to claim 1, wherein the second polymer layer is filtered through a filter having an average opening of 35 μm or less during melt extrusion. 8. The multilayer stretched film according to claim 1, wherein the first polymer layer is a polyester layer. 9. A stretched thermoplastic resin film comprising a first polymer layer obtained by peeling the multilayer stretched film according to any one of claims 1 to 8. 10. The stretched thermoplastic resin film according to claim 9, wherein the thickness of the stretched film comprising the first polymer layer is 0.5 to 50 μm. 11. The stretched film comprising the first polymer layer obtained by peeling the multilayer stretched film, wherein the number of transfer defects having a diameter of 90 μm or more from the second polymer layer is 0 to 20/3000 cm ^2. Item 11. The stretched thermoplastic resin film according to item 9 or 10.