JPH06297565A - Cover film - Google Patents

Abstract

PURPOSE:To obtain a flexible cover film which has few foreign matter or protrusions, less of its rough surface, and has an excellent release characteristic from a photoresist by using a polyester film with specified surface wet tensile strength and Young's modulus. CONSTITUTION:A cover film is made from a polyester film which has surface wet tensile strength of 36dyn/cm or less, and a Young's modulus of the polyester film is 10-250kg/mm. The polyester film used is, at least, one kind of the polyester film which is selected from the groups that consist of the polyester which contains dicarboxylic acid which has alkylene radicals of 10 or more of carbon atoms, and/or 5-50mol% of cyclohexane dicarboxylic acid, a polyester of copolymerized polycaprolactam, a polyester of copolymerized polyethylene glycol, and a polyester of copolymerized polytetramethylene glycol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cover film, particularly a photoresist cover film for photosensitive plate making. More specifically, the present invention relates to a photoresist cover film for photolithography, which is flexible, has a rough surface, is excellent in flatness, and has appropriate tackiness and releasability from a photoresist.

[0002]

2. Description of the Related Art Conventionally, a polyethylene or polypropylene film has been used as a photoresist cover film for photosensitive plate making (JP-A-1-179154).

It is preferable that the cover film has small thickness unevenness, good flatness, and few foreign matter protrusions (gel or fish eyes). Moreover, it must be flexible and have good releasability from the photoresist. Furthermore, dry film photoresist (hereinafter abbreviated as DFR) applies photoresist to a polyester film as a base material, attaches a cover film, and rolls the roll for a long time. Since there is a problem of self-crosslinking and there is a recent demand for lengthening the DFR, there is a demand for the cover film to be rough and thin.

Further, a film is known in which a polymethylpentene and a copolymer resin with other olefins are laminated on the surface layer of polypropylene for the purpose of improving the releasability (Japanese Patent Publication No. 57-44465, Japanese Patent Publication No. 3). -71975).

[0005]

However, the above-mentioned conventional polyethylene film has the drawbacks of large thickness unevenness and poor flatness, and many gel-like foreign matter protrusions, and is required as a DFR cover film. What
Making rough and thin films is very difficult. On the other hand, polypropylene film is easy to make a thin film with a rough surface, but it is too stiff and has poor releasability from the photoresist, resulting in the fact that the photoresist is prone to ripple ripples when peeling. have.

Further, a film obtained by laminating a copolymer resin of polymethylpentene and other olefins on the surface layer of polypropylene for the purpose of improving the releasability not only has a problem that the releasability is too weak, but also has a fish eye. There is also the drawback that there are many.

It is an object of the present invention to provide a flexible cover film which has a rough surface but little foreign matter and protrusions and has good releasability from a photoresist, particularly a photoresist cover film for photolithography.

[0008]

The cover film of the present invention which meets this purpose is a polyester film having a surface wetting tension of 36 dyn / cm or less, and the Young's modulus of the film is 10 to 250 kg / mm ^2. It is a characteristic cover film.

Flexible Polyester A which mainly constitutes the flexible polyester film having a small Young's modulus of the present invention
Regarding the dicarboxylic acid component constituting the polyester, aromatic dicarboxylic acid, alicyclic dicarboxylic acid, aliphatic dicarboxylic acid, polyfunctional acid and the like can be mentioned. Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid,
Phthalic acid, naphthalenedicarboxylic acid, diphenic acid, and derivatives thereof, and the like, alicyclic dicarboxylic acids include 1,4-cyclohexanedicarboxylic acid and derivatives thereof, and aliphatic dicarboxylic acids include adipic acid, There are sebacic acid, dodecanedioic acid, eicosic acid, dimer acid, and their derivatives, and typical polyfunctional acids are trimellitic acid, pyromellitic acid, and their derivatives. As the alcohol component, ethylene glycol, 1,4-butanediol,
1,6-hexanediol, neopentyl glycol,
Diethylene glycol, triethylene glycol, 1,
Typical examples are 4-cyclohexanedimethanol, bisphenol and their derivatives. Further, the flexible polyester A used in the present invention is a block with a polyester ether obtained by copolymerizing a polyether such as polyethylene glycol or polytetramethylene glycol, a polyester amide obtained by copolymerizing a polyamide, or an aliphatic polyester such as polycaprolactone. It also includes a copolymer and the like.

Among these polyesters, polyethylene terephthalate (P) is used from the viewpoints of film-forming properties such as stretching properties, humidity properties, heat resistance, chemical resistance, low cost properties and the like.
A polyester mainly composed of ET), preferably having 50 mol% or more of each of the acid component and the alcohol component of the polyester is terephthalic acid, ethylene glycol or a derivative thereof, is preferably used in the flexible polyester film of the present invention. Also, the glass transition temperature (T
When g) is 50 ° C. or less, flexibility and puncture strength are improved, which is preferable.

Further, in order to impart flexibility to the film, it is effective to copolymerize a polyester mainly composed of PET with an aliphatic dicarboxylic acid, a polyether or an aliphatic polyester. Copolymerization of a long-chain aliphatic dicarboxylic acid having 10 or more, preferably 20 or more alkylene groups is preferable in terms of flexibility and quality stability. Examples of the long-chain aliphatic dicarboxylic acid include dodecanedioic acid, eicosic acid, dimer acid and derivatives thereof, and in particular, the present invention may be a branched aliphatic dicarboxylic acid having a branched structure among them. From the viewpoint of improving impact resistance, it is preferable to use dimer acid among them in order to improve heat resistance and transparency.

Here, dimer acid is a general term for a mixture of a chain branched structure and a cyclic branched structure obtained by a dimerization / hydrogenation reaction of an unsaturated aliphatic dicarboxylic acid such as methyl oleate, and a methylene chain. Has 20 to 80 carbon atoms,
It is preferably 30 to 60. In addition, unsaturated bonds are usually left, but the bromine number measured by ASTM-D-1159 is 0.05 to 10 (g / 100g), preferably 0.1 to 5 (g / 100g). Has heat resistance,
It is preferable because it has excellent flexibility. The copolymerization amount of dimer acid is 1 to 40 mol%, preferably 5 to 20 mol% with respect to the acid component.

The flexible polyester A which mainly constitutes the flexible polyester film of the present invention is, for example, PET.
In the case of a copolyester with an aliphatic dicarboxylic acid or the like as a main component for imparting flexibility, the melting point, the glass transition point, and the crystallinity decrease, and in the stretched film manufacturing process, to the cooling drum during extrusion casting. Adhesion to a drawing roll, adhesion to a drawing roll, and adhesion to a clip in a tenter may easily occur, resulting in a decrease in productivity. Further, when the amount of copolymerization increases, the stretching characteristics of the polyester A alone deteriorate, and there is no one-to-one correspondence between the stretching and the stress, resulting in so-called necking stretching, which leads to deterioration of thickness unevenness. This poor drawing property is
In particular, it is particularly remarkable in a flexible polyester containing polybutylene terephthalate (PBT) as a main component, and for example, it is very difficult to obtain a smooth biaxially stretched film with a copolymerized PBT obtained by copolymerizing 15 mol% of dimer acid. is there.

From this point of view, the flexible polyester A
Of polyester B having a glass transition point of 45 ° C. or higher, preferably 55 ° C. or higher on at least one side of the above, in order to prevent sticking to rolls and clips in comparison with the preferable stretching temperature of polyester A. Is preferred.

As the polyester B, a crystalline polyester typified by PET is preferable from the viewpoint of preventing adhesion. Further, when the melting point and the glass transition point are higher than those of polyester A, the thermal dimensional stability of the film as a whole is improved, which is preferable. Furthermore, it is preferable to select a polyester having a breaking strength and Young's modulus higher than that of the polyester A after biaxial stretching, because the breaking strength and the like can be improved while keeping the stiffness of the film soft. Therefore, the lamination of the polyester B can have an effect of supplementing the disadvantages of the flexible polyester A, such as thermal stability and tensile strength, in addition to merely improving the film-forming property.

The dicarboxylic acid component, alcohol component, and copolymerization component such as polyether, polyamide and aliphatic polyester which compose the polyester B are the same as those of the polyester A, but in addition to the glass transition point, the polyester B further includes: Flexible polyester A with poor stretchability
It is preferable that the polyester has good stretching characteristics in order to assist the stretching characteristics. Specifically, a polyester containing PET as a main component, a polyester containing a polymer consisting of 1,4-cyclohexanedimethanol and terephthalic acid as a main component, and the like are preferable. PET, copolymerized PET with isophthalic acid, adipic acid, sebacine 4 carbon atoms such as acid
Examples thereof include copolymerized PET with an aliphatic dicarboxylic acid having an alkylene group of 8 to 8, and in the case of a copolymer, the amount of the copolymerized component is 1 to 40 mol%, preferably 5 to 20 mol%. Further, for the purpose of imparting releasability from the photoresist to the polyester B, other components such as polyethylene,
A crystalline polyolefin such as polypropylene or an amorphous polyolefin may be added, and among them, an amorphous polyolefin composed of a norbornene resin is preferable.

The polyester B is laminated on at least one surface of the flexible polyester A, and the thickness ratio thereof is 1 as the ratio of the total thickness of the layer made of polyester A and the total thickness of the layer made of polyester B. : 1 to 50: 1, preferably 2: 1 to 25: 1 (A layer total: B layer total). B
If the proportion of the layer is too small, the effect of improving the stretchability and the quality improvement are reduced, which is not preferable, and if the proportion of the layer B is large, the flexibility and puncture properties of the film are impaired, which is not preferable.

Lamination of polyester B is preferably carried out on both sides of flexible polyester A, which makes it easier to avoid the problem of sticking during film production and is more likely to occur in the case of two-layer films. It is easy to avoid the problem of curling. In addition, within the scope of the present invention, the polyesters B laminated on both surfaces of the flexible polyester A may be slightly different from each other in composition and the like.

B comprising polyester B in the present invention
By adding the inert particles to the layer, not only a film having a specific surface roughness can be obtained, but also opacity, concealing property, and slip property can be imparted.
Examples of the inert particles include inorganic compounds such as silicon oxide, aluminum oxide, zirconium oxide, calcium carbonate and magnesium carbonate, or infusible organic compounds such as crosslinked polystyrene, crosslinked divinylbenzene, benzoguanamine and silicone. Colloidal silica, pulverized silica, crosslinked polystyrene, silicone and the like are particularly preferable in terms of surface roughness and hiding power. The average particle size is preferably 0.1 to 10 μm, and more preferably 1 to 8 μm in order to improve the above properties of the film. The amount added is 2 to 20% by weight, preferably 5 to 1
It is 5% by weight. The polyester A may also contain the above-mentioned particles added to the polyester B or particles other than the above.

In the flexible polyester film of the present invention, additives such as an antistatic agent, a heat stabilizer, an antioxidant, a crystal nucleating agent, a weather resistance agent, an ultraviolet absorber, a pigment and a dye are impaired for the purpose of the present invention. It can be used to a lesser extent.
If necessary, surface irregularity processing such as embossing or sand matting, or surface treatment such as corona discharge treatment, plasma treatment, or alkali treatment may be performed. Furthermore, the flexible polyester film of the present invention is provided with an easy-adhesion treatment agent, an antistatic agent, a water vapor / gas barrier agent (such as polyvinylidene chloride), a release agent, a pressure-sensitive adhesive, an adhesive, a flame retardant, an ultraviolet absorber, and a matting agent. Coating, printing of pigments, dyes, etc. may be performed, and the purpose and method are not limited to the above.

The thickness of the flexible polyester film of the present invention is not particularly limited, but it is effectively used when it is 1 to 1000 μm, preferably 5 to 500 μm, more preferably 5 to 50 μm.

Further, as the polyester film, a polyester having a specific gravity of 0.5 to 1.2 having a cavity inside is also preferable from the viewpoint of low Young's modulus, high haze, rough surface and the like. To obtain a film having such voids, for example, Japanese Patent Publication No. 43-12013 and Japanese Patent Publication No. 60-30.
930, JP-A-2-29438, and JP-A-3-12002.
7. Resins incompatible with polyester, represented by JP-A-2-26739 and the like, olefin polymers such as polypropylene, polyethylene, polymethylpentene, and polyphenylene oxide, and inert particles such as calcium carbonate and barium sulfate. Inorganic particles such as titanium dioxide can be used alone or in combination with polyester to
A low specific gravity polyester film having many voids inside can be obtained by adding 50% by weight and then stretching. Of course, a polyester layer containing no internal voids or containing some internal voids may be thinly laminated on at least one surface of the low specific gravity film. If the specific gravity of the film is less than 0.5, wall opening tends to occur during peeling, which is not preferable, and conversely the specific gravity is 1.
This is because when it exceeds 2, properties such as surface roughening, haze and concealability cannot be imparted.

In the present invention, a cover film having a layer containing a wax-based composition as a main component on at least one surface of the above polyester film, preferably elongated protrusions having a length / width direction ratio of 3 or more on the surface. 20 /
It has 100 μm ² or more. The term "main component" as used herein means that the weight ratio in the laminated composition is 50% or more, preferably 60% or more. With the wax-based composition, various commercially available waxes such as petroleum-based waxes, plant-based waxes, mineral-based waxes, animal-based waxes, low molecular weight polyolefins and the like can be used, but are not particularly limited. In the present invention, the use of petroleum wax and vegetable wax is preferable in terms of releasability. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and oxidized wax. Among these, the use of oxidized wax is particularly preferable from the viewpoint of protrusion formation. Examples of the vegetable wax include candelilla wax, carnauba wax, wood wax, oliqury wax, sugar cane wax, rosin-modified wax and the like. In the present invention, a composition comprising the following compounds is particularly preferable. That is, {rosin or disproportionated rosin, or hydrogenated rosin / αβ-substituted ethylene (α-substituent: carboxyl, β-substituent: hydrogen or methyl or carboxyl) adduct / alkyl or alkenyl (each having 1 to 8 carbon atoms) poly ( Repeating unit: 1 to 6) Alcohol ester adduct} is preferable from the viewpoint of slipperiness and releasability, and more preferably mixed system with the above-mentioned oxidized wax. That is, after applying the composition, it is possible to form fine elongated protrusions by stretching in one direction, dissolved in water from the viewpoint of protrusion forming property, and explosion-proof, environmental pollution prevention, emulsification. , Suspended waxes are particularly preferred.

The mixing weight ratio of petroleum wax / vegetable wax is from 10/90 to 90/10, preferably 20/8.
0-80 / 20, more preferably 30 / 70-70 / 3
It is preferably 0. A vegetable wax content of 10% by weight or more is required for providing a uniform coating film having good slipperiness at high temperature and releasability, and good dispersibility when emulsified or suspended in water. Because it is suitable. The petroleum wax content of 10% by weight or more is due to good slipperiness due to projection formation of the coating film and good operability during high-speed laminating.

Further, in the present invention, when a mixture obtained by further adding an oily substance to the above wax-based composition is used, it is possible to obtain particularly excellent mold release / peelability in a severe region such as high temperature treatment. Here, the oily substance is a liquid or paste-like oil at room temperature, and examples thereof include vegetable oils, fats and oils, mineral oils, synthetic lubricating oils and the like. Vegetable oils include linseed oil, kaya oil, saffron oil, soybean oil, cinnamon oil, sesame oil, corn oil, rapeseed oil, tuna oil, cottonseed oil, olive oil, southern oil, camellia oil, castor oil, peanut oil, balm oil, coconut oil. And so on. Fats and oils include beef tallow, pork oil, sheep oil, cocoa oil, and the like, and mineral oils include machine oil, insulating oil, turbine oil, motor oil, gear oil, cutting oil, liquid paraffin, and the like. As the synthetic lubricating oil, those satisfying the requirements described in the Chemical Dictionary (Kyoritsu Publishing Co., Ltd.) can be arbitrarily used, and examples thereof include olefin polymerized oil, diester oil, polyalkylene glycol oil, and silicone oil. . Among these, mineral oil and synthetic lubricating oil, which have good running properties in the high pulse width region, are preferable. Also, a mixed system of these may be used.

The oily substance is 1 to 100 parts by weight, preferably 3 to 100 parts by weight with respect to 100 parts by weight of the wax composition.
It is preferable to add 50 parts by weight. When the amount of the oily substance is less than 1 part by weight, the peelability in the high temperature and high humidity region tends to decrease, and when it exceeds 100 parts by weight, the peelability in the low temperature and low humidity region tends to decrease. . In the above range, sticking does not occur in a wide range of temperature and humidity, and the peelability is good, which is particularly preferable.

Various additives may be used in combination in the above composition within a range that does not impair the effects of the present invention. Examples thereof include antistatic agents, heat-resistant agents, antioxidants, organic and inorganic particles, pigments and the like.

In addition, various additives such as dispersion aids, surfactants, preservatives and antifoaming agents may be added to the coating composition for the purpose of improving dispersibility in water or coating properties. good.

It is desirable that the thickness of the laminated film of the layer (laminated film) containing the wax-based composition as a main component is 0.005 μm or more, preferably 0.01 μm or more. When the thickness of the laminated film is less than 0.005 μm, sticking tends to occur.

In the present invention, a cover film having a layer containing 1 to 50% by weight of an amorphous polyolefin on at least one side of the above polyester film for imparting peelability to the film, preferably 2 to 30
%, And more preferably 5 to 20% by weight. Addition amount of amorphous polyolefin is 1
If the amount is less than 50% by weight, the effect is low. As the amorphous polyolefin, those having good compatibility with polyester are preferable, for example, "Apel" A manufactured by Mitsui Petrochemical Industry Co., Ltd.
PL6509 (amorphous polyolefin composed of norbornene-based resin) and the like can be mentioned, but not limited thereto.
Poor compatibility with polyester is not preferable because gelation occurs during film formation.

Here, the amorphous polyolefin is generally one in which the crystal melting point is difficult to be observed by thermal measurement, and a typical example of the amorphous polyolefin in the present invention is a hydride of dicyclopentadiene, One or more selected from a hydride of a copolymer of dicyclopentadiene and ethylene, a hydride of a copolymer of a reaction product of dicyclopentadiene and ethylene, and a norbornene-based polymer. This norbornene-based resin is preferable as the amorphous polyolefin, but a specific example thereof will be described below.

The norbornene-based resin referred to in the present invention has the general formula (1)

[Chemical 1] (However, in the formula, R ₁ and R ₂ may be the same or different from each other with respect to hydrogen, a hydrocarbon residue or a polar group such as halogen, ester, nitrile and pyridyl.
₁ and R ₂ may form a ring with each other. n is a positive integer and q is 0 or a positive integer. )

And / or general formula (2)

[Chemical 2] (However, in the formula, R ₃ and R ₄ may be the same or different from each other, and may be a hydrogen, a hydrocarbon residue, or a polar group such as halogen, ester, nitrile, and pyridyl.
₃ and R ₄ may form a ring with each other. l and m are positive integers, and p is 0 or a positive integer. The polymer which has a structural unit represented by these can be mentioned.

The polymer having the constitutional unit represented by the general formula (1) includes, for example, norbornene and its alkyl- and / or alkylidene-substituted compounds such as 5-methyl-2-norbornene, 5, and the like. 6
-Dicyclopentadiene such as dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene,
2,3-dihydrodicyclopentadiene, alkyl substitution products thereof such as methyl, ethyl, propyl and butyl, and dimethanooctahydronaphthalene substitution products of polar group such as halogen, alkyl and / or alkylidene substitution products thereof, halogen and the like. A substituted polar group of, for example, 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5
6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-dimethano-1,4,4a, 5
6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a,
5,6,7,8,8a-octahydronaphthalene, 6-
Chloro-1,4: 5,8-dimethano-1,4,4a,
5,6,7,8,8a-octahydronaphthalene, 6-
Cyano-1,4: 5,8-dimethano-1,4,4a,
5,6,7,8,8a-octahydronaphthalene, 6-
Pyridyl-1,4: 5,8-dimethano-1,4,4a,
5,6,7,8,8a-octahydronaphthalene, 6-
Methoxycarbonyl-1,4: 5,8-dimethano-1,
3,4,4a, 5,6,7,8,8a-octahydronaphthalene and other cyclopentadiene trimers, for example,
4,9: 5,8-dimethano-3a, 4,4a, 5,8,
8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-3a,
4,4a, 5,5a, 6,9,9a, 10,10a, 1
1,11a-dodecahydro-1H-cyclopentaanthracene and the like are used by one kind or two or more kinds, and a ring-opening polymer obtained by polymerization by a known ring-opening polymerization method is hydrogenated by a usual hydrogenation method. It is a polymer produced.

The polymer having the structural unit represented by the general formula (2) is a polymer obtained by addition-copolymerizing ethylene as a monomer with one or more of the above norbornene-based monomers by a known method. And / or hydrogenated products thereof, both of which are saturated polymers.

Further, the norbornene-based polymer is prepared by allowing α-olefins such as 1-butene, 1-pentene and 1-hexene to be present as a molecular weight regulator in the production steps of the general formulas (1) and (2). Alternatively, it may be a polymer copolymerized by adding other monomer components such as cycloolefin such as cyclopropene, cyclobutene, cyclopentene, cycloheptene, cyclooctene, 5,6-dihydrocyclopentadiene as a minor component. .

From the viewpoint of heat resistance, these polymers have a glass transition temperature of 70 ° C. or higher, preferably 80 to 15
It is 0 ° C. The molecular weight range is such that the number average molecular weight measured by GPC (gel permeation chromatography) analysis using cyclohexane as a solvent is 10,000 to 10
10,000, preferably 20,000 to 50,000. When the unsaturated bond remaining in the molecular chain is saturated by hydrogenation, the hydrogenation rate is 90% or more, preferably 95% or more, and particularly preferably 99% or more. By being a saturated polymer, weathering resistance and light resistance are improved.

The amorphous polyolefin of the present invention may be used alone or in combination of two or more. or,
You may blend the same kind but different thing in molecular weight.

Further, the amorphous polyolefin of the present invention may be added with an antioxidant, an antistatic agent, a lubricant, a surfactant, an ultraviolet absorber or the like.

Furthermore, the present inventors formed the following special protrusions on the surface of the layer to be laminated, and thus were excellent in stick resistance, releasability, releasability and handleability, which were not obtained in the past, and the photo resistance was improved. The inventors found a layer having excellent laminating property and adhesiveness on the resist surface. That is, in the present invention, 20 elongated protrusions having a length / width direction ratio of 3 or more are provided on the surface of a laminated film made of the composition described above.
It is preferably 0 μm ² or more. In addition, since it is a protrusion formed mainly of a wax-based composition or an oily substance, it will be in a molten state in a high temperature state such as heating, so that it is possible to obtain extremely excellent releasability and releasability unlike the protrusion formed by inorganic particles. Be done.

The Young's modulus of the film of the present invention is 10 to 250.
kg / mm ² , preferably 20-150 kg / mm ² ,
More preferably, the sum of Young's modulus in the longitudinal direction and the width direction is 5
It is preferably in the range of 0 to 150 kg / mm ² . This is because when the Young's modulus exceeds 250 kg / mm ² , the stiffness becomes too strong, the releasability from the photoresist deteriorates, and ripples and scratches and defects are likely to occur on the photoresist surface at the time of stripping. This is also because it is easy for air to be trapped when it is attached to the photoresist.

The surface wetting tension of the film of the present invention is 36 dy.
It should be n / cm or less, preferably 32 dyn / cm or less. This is for improving the releasability from the photoresist, and if the surface tension is other than this, the film is likely to be deformed at the time of peeling and a defect is likely to occur on the photoresist surface. Surface wetting tension can be controlled by surface coating. The haze of the film of the present invention is 10
% Or more, preferably 20 to 60%. This is because when the haze is less than 10%, the photoresist is photosensitively deteriorated by ultraviolet rays, and also because the cover film is colored, the handling property is improved.

The surface of the film has a roughness density PC-1 of 1 μm or more, preferably 2 to 5 μm, 10 pieces / mm.
It must be above. Roughness density PC-1 of 1 μm or more
Is 10 pieces / mm or more, it can be peeled smoothly without peeling unevenness when peeling from the photoresist,
Does not damage the photoresist. When the roughness density PC-1 of 1 μm or more is less than 10 pieces / mm, the adhesive strength with the photoresist becomes strong and the peeling property deteriorates, and the photoresist is unfavorably rippled.

When used as a cover film for DFR, the roughness density PC-1 of 1 μm or more is 10 pieces /
If it is less than mm, the photoresist in the core portion is in an oxygen-deficient state, which is not preferable. That is, in the DFR step of applying a photoresist to the biaxially stretched polyester film of the base material and sticking the cover film of the present invention and rolling in a roll shape, the photoresist and the cover film and the biaxially stretched polyester film of the base material and the book The air layer that has entered the minute space formed between the invention cover film and the photoresist of the winding core does not become oxygen deficient and can prevent self-crosslinking.

Next, the method for producing the cover film of the present invention will be described, but the method is not necessarily limited to this.

Polyester A and polyester B containing a large amount of an inorganic additive are fed to separate twin-screw vent extruders, melted at 200 to 300 ° C., and then polyester B / Polyester A
/ Polyester B 3-layer laminated sheet (thickness ratio 1:
1: 1 to 1: 100: 1) is extruded from a die, and electrostatically charged to bring it into close contact with a specular chrome-plated roll to rapidly cool it to obtain a cast sheet. The sheet thus obtained is 30 to 100 ° C.
After stretching 2 to 7 times between rolls in the longitudinal direction and cooling to room temperature and surface-activating the surface by corona discharge treatment, etc., a release agent mainly composed of vegetable wax, petroleum wax and oil-like substance (For example, JP-A-59-14869
7. A water dispersion of JP-A-60-56583) is coated with a known coater, immediately dried in a transverse stretching tenter, and then transversely stretched 2 to 5 times at 60 to 150 ° C., followed by heat setting. is there. Of course, if desired, any coating or surface treatment such as corona discharge treatment can be performed.

[0047]

[Physical Property Evaluation Method] The physical property and characteristic measurement and evaluation methods used in the description of the present invention and the examples described below will be described below.

(1) Melting point (Tm), glass transition temperature (Tg) It was measured using a differential scanning calorimeter DSC (manufactured by Perkin Elmer Co.). 280 samples of 10mg under nitrogen stream
The mixture was held at a temperature of 5 ° C. for 5 minutes and then quenched with liquid nitrogen. The specific heat change based on the transition from the glass state to the rubber state was read in the process of raising the temperature of the obtained sample at a rate of 10 ° C./min, and this temperature was taken as the glass transition temperature (Tg), and the endothermic peak temperature due to crystal melting was determined. The melting point (Tm) was used.

(2) Mechanical Properties AST for tensile Young's modulus, breaking strength and breaking elongation
It was measured according to MD-882-81 (method A).

(3) Roughness density PC-1 and surface roughness R
a It measured using the stylus type surface roughness meter as described in JIS-B-0601-1976. The cutoff was 0.25 mm and the measurement length was 5 mm.

(4) Haze Measured according to JIS-K-6714.

(5) Peelability A sample is laminated on a photoresist under a yellow lamp at 25 ° C. and cut into a width of 25 mm. After that, the film is peeled off by 90 ° in a tensile tester, and it is judged from the adhesive force, the peeling noise, and the photoresist surface state after peeling the sample.

◯: Peeling was smooth, there was no peeling noise, and there were no ripple-like scratches on the photoresist surface state after peeling the sample. Adhesive strength of 10 g / cm or less.

Δ: There is no peeling noise, but defects occur on the photoresist surface, and the adhesive strength is 10 to 50 g / c.
m.

X: Strong adhesion, peeling noise, and ripple-like scratches on the surface of the photoresist after peeling the sample.

(6) Surface Wetting Tension According to ASTM-D-2578 (67T), 20 ° C., 6
It measures in a 5RH% atmosphere.

(7) Self-crosslinking state of DFR photoresist After 500 m of DFR was wound and left under a yellow lamp at 25 ° C. for 6 months, the self-crosslinking state of DFR surface layer and winding core was observed.

◯: There was no self-crosslinking in the photoresist of the surface layer portion of the DFR and the core portion.

Δ: The photoresist in the surface layer portion or winding core portion of the DFR was partially crosslinked.

X: The photoresist in the surface layer portion or the winding core portion of the DFR was entirely crosslinked.

(8) Laminating Property When the film of the present invention was laminated on the photoresist layer, the case where there was no wrinkle or the inclusion of air was marked with ◯, and the other cases were marked with x.

[0062]

The present invention will be described below with reference to examples.

Example 1 A known method using 85 mol% of terephthalic acid as a dicarboxylic acid component, 15 mol% of hydrogenated dimer acid having 36 carbon atoms and 100 mol% of ethylene glycol as a diol component (measured at 25 ° C. orthochlorophenol). And the intrinsic viscosity is 0.
75 copolyester A (Tm222 ° C, Tg17
C) was obtained. On the other hand, 100 mol% of terephthalic acid as a dicarboxylic acid component, 100 mol% of ethylene glycol as a diol component, and silicon oxide having an average particle diameter of 2 μm were added so as to be 15% by weight. Copolyester B (Tm233 ° C, Tg
55 ° C.) was obtained.

After drying these two types of copolyester with a known vacuum dryer, polyester A is 250 mmφ
Polyester B is fed to the extruder of 60 mmφ and the polyester A is 260 ° C. and the polyester B is 2 mm.
Melt at 85 ° C to make polyester B / polyester A / polyester B (lamination thickness ratio 1: 30: 1) 3
After stacking in layers, it was expanded in the width direction in the die and discharged in a sheet form from 1.0 mm slits. While applying an electrostatic charge to the sheet, the sheet was closely cooled and solidified on a casting drum kept at 25 ° C., and then 3.3 ° C. at 70 ° C. with a stretching roll.
After longitudinal stretching twice, corona treatment, coating with an aqueous dispersion of the release agent described below, drying in a tenter at 80 ° C, lateral stretching 3.3 times, and heat treatment at 210 ° C for 5 seconds. A biaxially stretched flexible polyester film having a thickness of 15 μm (coating thickness 0.08 μ) was obtained.

[Release Agent Coating Composition] (a) 50 parts by weight of plant wax {hydrogenated rosin / αβ-substituted ethylene (α-substituent: carboxyl, β-substituent: methyl) adduct / alkyl (carbon number:
6) Poly (repeating unit: 5) Alcohol ester compound} (b) Oxidized wax 50 parts by weight To form an aqueous dispersion of the above (a) and (b), a nonionic surfactant, a phosphate ester (butoxy) Ethyl compound),
Ammonium oleate and 2-amino-2-methylpropanol were each added in an amount of 1 part by weight, and the mixture was vigorously stirred in water, and an ultrasonic dispersion machine was used to prepare an aqueous dispersion having a total solid content of 1.0 wt%.

In order to evaluate the release agent-coated surface of the film of the present invention thus obtained as a photoresist cover film for DFR photosensitive plate making, a photoresist coated and dried on a biaxially stretched polyethylene terephthalate film as a substrate is used. The layer (consisting of a combination of a monomer, oligomer or polymer having an epoxy group and a diazonium salt) was roll-pressed at room temperature under a yellow lamp at 20 ° C. and rolled into a long roll.

Table 1 shows the results of the evaluation of the film quality characteristics and the photoresist cover film for photosensitive plate making. As is apparent from the table, the film of the present invention was a rough surface with few foreign matter protrusions such as gels and fish eyes, and was excellent in laminating property on a photoresist and releasability. Further, the DFR had good air flowability and did not undergo self-crosslinking due to oxygen deficiency of the photoresist in the winding core.

Examples 2, 3 and Comparative Example 1 A flexible biaxially stretched film (15 μm) having a release layer was prepared in exactly the same manner as in Example 1 except that the polyester A used in Example 1 was changed. Got

[0069]

[Table 1] Example 4, Example 5, Example 6 A flexible biaxially stretched film was formed in exactly the same manner as in Example 1 except that the addition amount of silicon oxide added to the polyester B used in Example 1 was changed. Was obtained (15 μm).

[0070]

[Table 2] Example 7, Comparative Example 2 A 15 μm flexible polyester film was obtained in exactly the same manner as in Example 1 except that the release agent coating used in Example 1 was changed.

[0071]

[Table 3] Example 8 As polyester A, polyethylene terephthalate (intrinsic viscosity 0.65, Tm 264 ° C., Tg 69 ° C.) 10
4-methylpentene polymer (Mitsui Petrochemical "TP
X ″ 840) was mixed in an amount of 10 parts by weight and polytetramethylene glycol in an amount of 1 part by weight, and a low specific gravity (0.7) having voids was prepared in the same manner as in Example 1.
A white biaxially stretched film (3) of 3) was obtained.

Example 9 A known method using 90 mol% of terephthalic acid as a dicarboxylic acid component, 10 mol% of hydrogenated dimer acid having 36 carbon atoms and 100 mol% of ethylene glycol as a diol component (measured at 25 ° C. orthochlorophenol). And the intrinsic viscosity is 0.
74 Copolyester A (Tm 235 ° C, Tg 34
C) was obtained. On the other hand, polyester B uses 100 mol% of terephthalic acid as the dicarboxylic acid component and 100 mol% of ethylene glycol as the diol component, and has an intrinsic viscosity of 0.
65 polyethylene terephthalate (Tm 265 ° C, Tg
69 ° C.) was obtained.

After drying these two types of polyester in a known vacuum dryer, polyester A was added to a 250 mmφ extruder and polyester B was made to have 12% by weight of "Apel" APL6509 (manufactured by Mitsui Petrochemical Industry Co., Ltd.). Was added to a 60 mmφ extruder, extruded in the same manner as in Example 1, cast, and then stretched at 70 ° C. with a stretching roll at 3.7.
After the double stretching, the transverse stretching was performed at 90 ° C. for 3.6 times in a tenter to obtain a biaxially stretched flexible polyester film having a thickness of 15 μm, which was heat-treated at 200 ° C. for 5 seconds.

[0074]

[Table 4]

[Table 5] As described above, it is necessary to specify limited Young's modulus, surface wetting tension, haze, surface roughness, etc. in order to exhibit excellent properties as a cover film.

[0075]

As described above, the photoresist cover film of the present invention has the following excellent effects because the surface of the flexible film is roughened and the surface wetting tension and transparency are limited. Occurs.

(1) Small thickness unevenness and good flatness,
There are few protrusions such as gels and fish eyes, and DF
The appearance when R is good.

(2) Flexible and excellent in releasability from the photoresist.

(3) Since the surface to be bonded to the photoresist is a specific rough surface layer, there is no large air entrapment during roll pressure bonding, the process stability is excellent, and the appearance when DFR is good.

(4) Further, by using a specific rough surface layer, the air flowability in the case of DFR is good, and the photoresist of the core does not self-crosslink due to oxygen deficiency.

(5) Since the film haze is high, D
Prevents the surface layer portion of FR from being crosslinked by ultraviolet rays.

Claims (8)

[Claims] 1. A cover film made of a polyester film having a surface wetting tension of 36 dyn / cm or less, wherein the Young's modulus of the polyester film is 10 to 25.
A cover film having a weight of 0 kg / mm ² . 2. The haze of the polyester film is 10%.
It is above, The cover film of Claim 1 characterized by the above-mentioned. 3. The cover film according to claim 1, wherein the polyester film has a roughness density PC-1 of 1 μm or more of 10 pieces / mm or more. 4. The polyester film comprises (a) 5 to 5 long-chain aliphatic dicarboxylic acid and / or cyclohexanedicarboxylic acid having an alkylene group having 10 or more carbon atoms.
0 mol% of polyester, (b) Polycaprolactone block-copolymerized polyester, (c)
A film made of at least one polyester selected from the group consisting of block copolymerized polyesters of polyethylene glycol and (d) block copolymerized polytetramethylene glycol. Claim 1 to claim 3
The cover film according to any one of 1. 5. The cover film according to any one of claims 1 to 4, wherein the polyester film is a polyester film having a void inside and a specific gravity of 0.5 to 1.2. 6. The cover film according to claim 1, which has a layer containing a wax-based composition as a main component on at least one surface of the polyester film. 7. The cover film according to claim 1, which has a layer containing 1 to 50% by weight of an amorphous polyolefin on at least one surface of the polyester film. 8. The cover film according to claim 7, wherein the amorphous polyolefin is a norbornene-based resin.