JPH06255060A - Laminated polyester film - Google Patents

Abstract

PURPOSE:To provide a mold release laminated polyester film having excellent mold release properties, blocking resistance, chemical-resistance, etc., and additionally adapted for utility of a transfer foil, a tire, a PVC marking film, fomentation, a lapping,tape, plaster, etc. CONSTITUTION:A mold release laminated polyester film is obtained by forming a coating film made of polypropylene wax water emulsion having 32 dynes/cm or less of surface free energy and 0.005mum or more of a dry film thickness at least on one side surface of a polyester film.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a releasable laminated polyester film. More specifically, it retains slipperiness and is excellent in releasability. For example, transfer foil, tire, P
VC marking film, poultice, wrapping tape,
The present invention relates to a releasable film made of a polyester film capable of maintaining and exhibiting excellent releasability for a plaster or the like for a long time.

[0002]

2. Description of the Related Art Polyester films, particularly biaxially stretched polyethylene terephthalate films, have excellent mechanical properties, heat resistance, chemical resistance and the like, and therefore, magnetic tape, photographic film, packaging film, It is widely used as a material for diazo easy-adhesion film, capacitor metallizing film, electrical insulating film, writing film, etc. One of the fields of use thereof is the field of release films such as release films for stamping and wrapping tape. This is because the biaxially oriented polyester film is stretched biaxially and has a high surface cohesiveness due to the crystal orientation, so it is generally poor in the acceptance of paints, adhesives and inks, and this inactive surface state It can be said that this is a field of application for effectively utilizing. However, when the polyester film alone is used for various release materials, the release effect may be poor and a part where the resin and the release material adhere may appear, or adhesion may occur between the release film and the resin. I'm not satisfied. In particular, it could not be used at all in applications such as stamping.

On the other hand, as a sheet material having a releasing performance as an alternative to polyester, there are silicone releasing paper, polytetrafluoroethylene resin sheet and the like. However, the former is not appropriate because it has a problem in terms of heat resistance, has a problem that strength is greatly decreased in a wet state as a characteristic peculiar to paper, and is weak against flexible tearing. Although the release property of the tetrafluoroethylene resin sheet material is good, it is opaque as a film and its internal properties cannot be observed. Further, the copolymer is excellent in transparency and heat resistance, but has a drawback of large thermal deformation, so that it cannot be said to be a suitable release material.

Therefore, attempts have been made to provide one release layer on the surface of the film by utilizing the characteristics of the biaxially oriented polyester film. For example, a silicone resin is applied thinly on the surface. However, this coating film, the release agent does not spread evenly on the film surface during production,
It tends to be speckled. If the coating film is formed unevenly, the release agent may be transferred to the processed product, which is one of the drawbacks of this coating film.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laminated polyester film having improved release performance.

[0006]

In order to achieve the above object, the present invention has a layer of a polypropylene wax aqueous emulsion laminated on at least one side of a polyester film, and the surface free energy of the coating film is 32 dyn.
/ Cm or less, and the dry film thickness of the coating film is 0.005
It is achieved by a laminated polyester film having a thickness of at least μm.

The polyester constituting the polyester film in the present invention is a general term for polymers having an ester bond as a main connecting chain, and particularly preferable polyesters are polyethylene terephthalate and polyethylene 2 , 6-naphthalate, polybutylene terephthalate, polyethylene α, β-bis (2-chlorophenoxy) ethane 4,4-dicarboxylate and the like, among which, in terms of quality and economical efficiency, Considering this, polyethylene terephthalate is most preferable. Therefore, polyethylene terephthalate (hereinafter abbreviated as PET) will be described below as a representative example of polyester. PE
T is 80 mol% or more, preferably 95 mol% or more, which has ethylene terephthalate as a repeating unit. Within this limited amount range, other dicarboxylic acid components, di-
It may be used as an ingredient. Further, known additives such as heat resistance stabilizer, oxidation resistance stabilizer, weather resistance stabilizer, UV absorber, organic lubricant, dye, organic or inorganic fine particles, filler, antistatic agent, nucleating agent, etc. You may mix these. The PET film described above has an intrinsic viscosity of 0.40 to 1.20 d (measured in orthochlorophenol at 25 ° C.).
l / g, preferably in the range of 0.50 to 0.80 dl / g is suitable for the present invention.

The polyester film of the present invention is preferably biaxially oriented in the laminated state of the coating film in view of mechanical and thermal characteristics. For example, when the above PET is used as polyester, Axial oriented PET
The film is made by stretching a PET sheet or a film in a non-stretched state in the longitudinal direction and the transverse direction by about 2.5 to 5 times each, and is a biaxially oriented pattern in wide-angle X-ray diffraction. Refers to. The thickness of the PET film is not particularly limited, but is usually 5 to 500 μm, more preferably 10 to 250 μm, and may be arbitrarily selected depending on the application.

The polypropylene wax emulsion used in the present invention is an aqueous emulsion of propylene homopolymer. The propylene polymer preferably has a molecular weight of 2000 or more. Further, the viscosity is preferably 100 cps or less from the viewpoint of handleability, and the ionicity is preferably nonion or anion, and one having good dilution stability is preferable.

The aqueous emulsion is not particularly limited by its production method, and for example, a hot melt of the (A) propylene polymer is added to hot water containing a surfactant under high speed stirring to finely disperse the same. Method: (B) A method in which an organic solvent solution of a propylene polymer is added to water containing a surfactant under high-speed stirring to finely disperse it, and if necessary desolvation is carried out:
(C) A propylene polymer mechanically finely pulverized, which is produced by a method of stably dispersing it in water containing a surfactant, can be used. At that time, the amount of the propylene polymer is 50 to 1 with respect to the total solid content contained in the aqueous liquid.
00 wt% is preferable, and 70 to 100 wt% is more preferable. The solid content concentration in the aqueous liquid is preferably about 5 to 70 wt%, though it depends on the coating method.
About 10 to 50 wt% is preferable. This polypropylene aqueous liquid is added with additives such as colorants, fillers, catalyst stabilizers, surfactants, waxes and oils, as long as the effect of imparting releasability, which is the greatest feature of the present invention, is not impaired. There is no particular problem. The content of these additives is
As described above, it is not particularly limited as long as it does not hinder the effect of imparting releasability, but it is usually about 30% by weight or less.

The surface free energy of the polypropylene wax coating film of the present invention is 32 dyn / cm or less, preferably 30 dyn / cm or less. It is more preferable that the dispersive force component of the surface free energy is 27 dyn / cm or less, the polar force component is 2 dyn / cm or less, and the hydrogen bonding component is 3 dyn / cm or less. The surface free energy of the coating film is 32.
If it exceeds dyn / cm, the releasability of the coating layer becomes poor, which is not preferable. The surface free energy of a solid and its components such as a dispersive force component, a polar force component and a hydrogen bonding component can be determined by the so-called Kaelble method, and the details are described in J. Polym. Sc
i, A-2, 9, 363 (1971).
The present inventors have found that the value of surface free energy is 32 dyn /
A new finding has been obtained that excellent releasability is obtained when the pressure is less than or equal to cm, preferably less than or equal to 30 dyn / cm.

There is no need to use any special method for applying the polypropylene aqueous solution, and any known coating method may be used. For example, river coating, kiss coating, air-knife coating, spray coating, brush coating,
And gravure coating can be applied. After applying the polypropylene aqueous liquid, by evaporating the water solvent,
A coating of polypropylene polymer can be formed on the surface of the polyester film. The evaporation of the water solvent by heating is preferably carried out at a temperature below which the film can maintain its shape. In the present invention, the polyester coated with the aqueous solution of polypropylene wax is preferably a uniaxially stretched and oriented polyester film, particularly a longitudinally (longitudinal) stretched and oriented polyester film. Applied to a uniaxially stretched and oriented polyester film,
This is because the polypropylene wax is more strongly applied to the surface of the polyester film by being dried and transversely stretched.

When applying the aqueous solution of polypropylene wax, in order to obtain a higher degree of adhesion with the polyester film, activation treatment such as corona treatment, plasma treatment, mat processing, embossing processing, sandblast processing, etc. are not performed in advance. No problem, but rather preferable.

In the present invention, the coating film thickness of the aqueous solution of polypropylene wax may be the minimum film thickness at which the effect is exhibited, and it is not necessary to unnecessarily increase the film thickness. The minimum film thickness at which the effect is exerted is 0.005 μm or more, preferably 0.01 μm or more, more preferably 0.05 μm or more in terms of releasability. When the film thickness is 0.005 μm or less, uniform coating is difficult and the releasing effect is difficult to be exhibited. The upper limit of the film thickness is not particularly limited, but 0.3 μm or less is preferable from the viewpoint of economy, coating property, process and the like.

As mentioned above, the polyester in the present invention means an aromatic dibasic acid or its ester-forming derivative (eg lower alkyl ester, aryl ester, etc.) and diol or its ester-forming derivative. (For example, lower fatty acid ester, ethylene oxide, etc.)
It is a linear saturated polyester synthesized from. Examples of the aromatic dibasic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 4,4,-(or 3,4,) diphenyldicarboxylic acid, 4, 4,-(or 3,4,
) Diphenyl sulfone dicarboxylic acid, 4,4,-(or 3,4,) diphenyl ether dicarboxylic acid,
4,4,-(or 3,4,) diphenylethanedicarboxylic acid and the like can be mentioned. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred.
As the diol, for example, ethylene glycol,
Trimethylene glycol, tetramethylene glycol,
Hexamethylene glycol, Octamethylene glycol
, 1,4-cyclohexane dimethanol, neopentyl glycol, diethylene glycol, and other aliphatic diols, hydroquinone, resorcin, 2,2, -bis (4-hydroxyphenyl) sulfone, 2, Examples thereof include aromatic diols such as 2, -bis (4-hydroxyethoxyphenyl) propane. Of these, ethylene glycol is particularly preferable.

Specific preferred examples of the polyester include:
Polyethylene terephthalate, copolyester containing ethylene terephthalate as a main repeating unit (preferably 80% or more repeating units), polyethylene-2,6
Examples thereof include naphthalate and copolyester having ethylene-2,6-naphthalate as a main repeating unit (preferably 80% or more repeating units).

The polyester in the present invention is a polymer.
May be copolymerized with a polyfunctional compound having three or more functional groups in an amount range that is substantially linear, and the terminal of the polymer may be modified with a monofunctional compound.

The polyester of the present invention naturally has a film-forming ability. For example, in the case of polyethylene terephthalate, the intrinsic viscosity is usually 0.4 or more, preferably 0.5 or more (orthochlorophenol). ,
25 ° C.).

The unstretched polyester film in the present invention can be produced by melt-extruding such polyester from a die and quenching. Usually, it can be produced by quenching a melt extruded from a die on a casting drum. This unstretched polyester film is subjected to a biaxially stretched orientation treatment and a crystallization heat treatment, for example, by a method known in the art to obtain a biaxially oriented polyester film. This crystallization heat treatment is a treatment called heat set. The biaxially stretched orientation is preferably a sequential biaxially stretched orientation treatment, and the stretching magnification is at least 2 times, further 2.5 times or more, and area magnification 6 times or more, further 9 times or more. It is preferable. The heat setting is preferably carried out at a temperature of 170 ° C. or higher, more preferably 190 ° C. or higher for a few seconds to a few minutes, more preferably 5 seconds to 20 seconds.

According to the present invention, it is possible to obtain a laminated polyester film which retains slipperiness and is excellent in releasability, and the film is used, for example, under various conditions such as a transfer foil, a tire and a PVC matrix. -It is possible to maintain and develop excellent releasability for a king film, wrapping tape, plaster, etc. for a long time.

Next, a preferred example of the manufacturing method of the present invention will be described, but the present invention is not limited to this.
First, polyester pellets polymerized by a conventional method are sufficiently dried and then fed to a known extruder, and the sheet is cut from a slit die at a temperature not lower than the melting temperature of the pellets and not higher than the temperature at which the polymer decomposes. It is melt extruded and cooled and solidified to prepare an unstretched sheet. At this time, the polyester pellets of the raw material to be used may have internal particles and inert particles based on the residue of the polymerization catalyst etc., but in order to obtain a more transparent film, the pellets should not contain such particles as much as possible. Is preferred. Further, other polyesters may be copolymerized or external particles may be added as long as the effects of the present invention are not impaired. The intrinsic viscosity of the unstretched sheet is preferably 0.5 or more in view of film characteristics. Further, from the viewpoint of preventing crystallization of the unstretched sheet, the temperature of the casting drum is kept as low as possible (20 to 30 ° C), and electrostatic is applied to the film surface to enhance the cooling effect. Make sure the film is in close contact, and if necessary air
It is preferable to cool the non-drum surface of the cast film by using a chamber, an air knife or the like to suppress crystallization. Crystallization is not preferable because not only troubles in the film-forming process easily occur, but also haze increases and transparency is impaired. Next, the unstretched sheet is
A coating agent prepared in a predetermined amount is applied onto a film stretched 3.0 to 4.0 times at 100 ° C., the coating film is dried to provide a predetermined coating layer, and then 3.0 at 90 to 110 ° C. 〜4.0 times transverse stretching. Further, it is effective to stretch at a minimum necessary temperature for both the longitudinal stretching temperature and the transverse stretching temperature in order to suppress crystallization and obtain a highly transparent film. Furthermore, the biaxially oriented film gives a relaxation of 0 to 10% at 200 to 240 ° C.
Heat treatment for ~ 20 seconds.

The coating method is a gravure coating method, a reversal coating method, a kiss coating method, a die coating method of a coating material dispersed in water because a thin film coating can be performed at a high speed. It is preferable to apply a known method such as a coating method or a metalling bar coating method. At this time, by applying a known surface treatment such as corona discharge treatment in air or other various atmospheres on the film as needed before coating, not only the coating property is improved but also the coating film is formed. Can be more firmly formed on the film surface. The concentration of the coating material and the conditions for drying the coating film are not particularly limited, but it is preferable to perform the conditions for drying the coating film in a range that does not adversely affect various properties of the polyester film. In order to obtain the coating film of the present invention, the coating amount is 0.005 to 0.3 g / m ² , preferably 0.01
To 0.25 g / m ² , more preferably 0.05 to 0.1
A range of 5 g / m ² (dry weight in each case) is desirable. If the coating amount is 0.005 g / m ² or less, uniform coating is difficult,
The release effect is inferior, sufficient slipperiness cannot be imparted, and if it is 0.3 g / m ² or more, there are problems in economic efficiency, coatability, and process, which is not preferable. As described above, the releasable laminated polyester film of the present invention can be produced.

The evaluation method of measuring methods and effect of characteristics in assays present invention is as follows.

(1) Thickness of coating layer Using a transmission electron microscope HU-12 manufactured by Hitachi, Ltd., an ultrathin section of the laminated film is observed to determine the thickness.

(2) Releasability (Releasability of Undercoat Layer) On the release layer side of the releasable laminated polyester, a coating composition for aluminum vapor-deposited transfer foil underlayer (modified acrylic resin + isocyanate curing agent) Type) to a thickness of about 1.5 .mu.m, and a Nichiban Co., Ltd. cello tape (24 mm width) was adhered to the undercoat layer, and then the cello tape was peeled off to form an undercoat. The easiness of peeling between the release layer and the release laminated polyester film was judged according to the following criteria. ◯: The undercoat layer peels off with almost no resistance Δ: There is some resistance, but it peels off cleanly X: Peeling but strong resistance XX: No peeling at all

(3) Peeling force Nichiban Co., Ltd. was applied to the release layer side of the releasable laminated polyester.
After sticking a cello tape (24 mm width) and making it adhere, 90 ° peeling angle, 200 m by a shopper type tensile tester
Cellotepe peeling force at a pulling speed of m / min (g / 24 mm
Width).

(4) Surface free energy: According to a known method, four kinds of liquids of water, ethylene glycol, formamide, and methylene iodide were used as measurement liquids, and contact angles manufactured by Kyowa Interface Science Co., Ltd. The static contact angle of each liquid with respect to the film surface was determined using a total CA-D type. The contact angles obtained for each liquid and the components of the surface tension of the measured liquid were substituted into the following equations, respectively, and a simultaneous equation consisting of four equations was solved for γS ^d , γS ^p , and γS ^h . ^{(ΓS d γL d) 1/2 +} (γS p γL p) 1/2 + (γS h γL h)
^{1/2 = γL (1 + COS θ} ) / 2 ^{where, γS = γS d + γS p} + γS h γL = γL d + γL p + γL h γS, γS d, γS p, γS h is the surface free energy of each film surface -, dispersion Force component, polar force component, hydrogen bond component, and γL, γL ^d , γL ^p , and γL ^h are the surface free energy of the measurement liquid used, the dispersion force component, the polar force component,
Takes to represent the hydrogen bonding component. Here, the surface tension of each liquid used is Panzer (J. Panzer, J.
Colloid Interface Sci. , 4
4, 142 (1973) was used.

(5) Chemical resistance The surface of the release layer of the release film is methyl ethyl ketone (M
EK) Apply a 50g load with a cotton swab moistened with the solvent to obtain 10
The state of the release layer at the time of rubbing was judged according to the following criteria. ◯: No change at all Δ: Whitening but not dissolution ×: Complete release layer dissolution

(6) Blocking resistance 500 g / 12 cm on a film having a release layer provided on which coating surfaces are superposed (overlapping area: 3 cm × 4 cm).
^After a load of ² was applied and the mixture was left standing at 50 ° C. and 80% RH for 24 hours, the shear stress of the overlapped portion was measured at a tensile speed of 20 cm / min using a Tensilon tensile tester, and judged according to the following criteria. ◯: 0 kg / cm ² or more and less than 0.5 kg / cm ² Δ: 0.5 kg / cm ² or more and less than 2.0 kg / cm ² ×: 2 kg / cm ² or more

(7) Solution haze of chips To 20 ml of a well-known polyethylene terephthalate solvent,
The chip 3g was melt | dissolved and it put in the quartz cell of thickness 20mm, and measured the solution haze. (Measuring temperature 25 ℃)

[0031]

EFFECTS OF THE INVENTION The film of the present invention has a coating film made of a polypropylene wax emulsion formed on a polyester film, and therefore has excellent releasability, slipperiness, blocking resistance, chemical resistance and the like. Foil, tire, P
It is possible to maintain and develop excellent releasability for a VC marking film, wrapping tape, plaster, etc. for a long time.

[0032]

EXAMPLES The present invention will be described more specifically below based on examples. However, the present invention is not limited to the following examples.

Example 1 Polyethylene terephthalate homopolymer chips having a solution haze of 0.8% (intrinsic viscosity =
0.65, melting point: 262 ° C.) was dried under reduced pressure (2 mmHg) at 180 ° C. for 2 hours. This chip was supplied to an extruder at 285 ° C., melt-extruded from a T-shaped die, wound around a cooling drum having a surface temperature of 20 ° C. by an electrostatic application method, and cooled and solidified to obtain an unstretched film. At 95 ° C
Polypropylene wax emulsion (composition: polypropylene wax emulsion manufactured by Toho Chemical Industry Co., Ltd., E-433N, emulsion solid content concentration 30) % By weight) on one side of the uniaxially stretched film by a metering bar coat method, and then while the coating layer is being dried, it is stretched 3.3 times in the transverse direction at 105 ° C. and 5 times in the transverse direction.
%, And heat-treated at 225 ° C. for 5 seconds to obtain a laminated polyester film having a thickness of 25 μm in which a coating film thickness of 0.08 μm after biaxial stretching was laminated. The respective properties of this laminated polyester film are shown in Table 1. As can be seen from Table 1, a releasable laminated polyester film having excellent releasability, chemical resistance, blocking resistance and the like was obtained.

Example 2 A releasable laminated polyester film having a thickness of 25 μm was obtained in the same manner as in Example 1, except that the thickness of the polypropylene wax of Example 1 after drying was changed to 0.15 μm. It was The properties of the laminated polyester film are shown in Table 1. As shown in Table 1, when the laminated polyester film is within the range of the present invention, a laminated polyester film having good releasability, chemical resistance, blocking resistance and the like can be obtained, but it is out of the range of the present invention (comparative). In Examples 1 to 3), it can be seen that a releasable laminated polyester film having excellent properties cannot be obtained.

Example 3 A releasable laminated polyester film having a thickness of 25 μm was obtained in the same manner as in Example 1 except that the thickness of the polypropylene wax of Example 1 after drying was 0.20 μm. It was The characteristics of the releasable laminated polyester film are shown in Table 1.
It was shown to.

Comparative Example 1 A releasable laminated polyester film having a thickness of 25 μm was obtained in exactly the same manner as in Example 1 except that the thickness of the polypropylene wax after drying was 0.003 μm, which is outside the range of the present invention. It was The properties of the obtained laminated polyester film are shown in Table 1, but it is understood that it is not possible to obtain a releasable laminated polyester film which is excellent in each property outside the scope of the present invention.

Comparative Example 2 A laminated polyester film having a thickness of 25 μm was obtained in the same manner as in Example 1 except that a polyethylene wax emulsion was used in place of the polypropylene wax emulsion. . The respective properties of this laminated polyester film are shown in Table 1. As can be seen from Table 1, since a coating material outside the scope of the present invention was used, a laminated polyester film having excellent releasability could not be obtained.

COMPARATIVE EXAMPLE 3 A polyethylene terephthalate homopolymer chip having a solution haze of 0.8%, produced by a conventional method (intrinsic viscosity =
0.65, melting point: 262 ° C.) was dried under reduced pressure (2 mmHg) at 180 ° C. for 2 hours. This chip was supplied to an extruder at 285 ° C., melt-extruded from a T-shaped die, wound around a cooling drum having a surface temperature of 20 ° C. by an electrostatic application method, and cooled and solidified to obtain an unstretched film. At 95 ° C
The film was stretched 3.3 times in the machine direction by a vertical stretching process and subjected to corona discharge treatment on the surface.
The film was stretched 3.3 times in the transverse direction at 5 ° C. and heat-treated at 225 ° C. for 5 seconds while relaxing 5% in the transverse direction to obtain a 25 μm-thick single-layer polyester film. Table 1 shows the characteristics of this single-layer polyester film. As can be seen from Table 1, the film exhibited no releasability.

[0039]

[Table 1]

Claims (1)

[Claims] 1. A layer comprising a polypropylene wax aqueous emulsion is laminated on at least one side of a polyester film, and the surface free energy of the coating film is 32 dyn.
/ Cm or less, and the dry film thickness of the coating film is 0.005
A laminated polyester film having a thickness of at least μm.